WO2013180028A1 - Thermoplastic resin foam and foam sealant - Google Patents

Thermoplastic resin foam and foam sealant Download PDF

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Publication number
WO2013180028A1
WO2013180028A1 PCT/JP2013/064473 JP2013064473W WO2013180028A1 WO 2013180028 A1 WO2013180028 A1 WO 2013180028A1 JP 2013064473 W JP2013064473 W JP 2013064473W WO 2013180028 A1 WO2013180028 A1 WO 2013180028A1
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Prior art keywords
resin foam
thermoplastic resin
resin
foam
thickness
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PCT/JP2013/064473
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French (fr)
Japanese (ja)
Inventor
和通 加藤
齋藤　誠
逸大 畑中
清明 児玉
Original Assignee
日東電工株式会社
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Priority to CN201380028051.9A priority Critical patent/CN104334620A/en
Publication of WO2013180028A1 publication Critical patent/WO2013180028A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
    • C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/26—Porous or cellular plastics
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
    • C08J2201/026—Crosslinking before of after foaming
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
    • C08J2201/03—Extrusion of the foamable blend
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2203/00—Foams characterized by the expanding agent
    • C08J2203/06—CO2, N2 or noble gases
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2203/00—Foams characterized by the expanding agent
    • C08J2203/08—Supercritical fluid
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2205/00—Foams characterised by their properties
    • C08J2205/04—Foams characterised by their properties characterised by the foam pores
    • C08J2205/044—Micropores, i.e. average diameter being between 0,1 micrometer and 0,1 millimeter
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2205/00—Foams characterised by their properties
    • C08J2205/06—Flexible foams
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2300/00—Characterised by the use of unspecified polymers
    • C08J2300/22—Thermoplastic resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2300/00—Characterised by the use of unspecified polymers
    • C08J2300/26—Elastomers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/10—Homopolymers or copolymers of propene
    • C08J2323/12—Polypropene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/16—Ethene-propene or ethene-propene-diene copolymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2400/00—Characterised by the use of unspecified polymers
    • C08J2400/22—Thermoplastic resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2400/00—Characterised by the use of unspecified polymers
    • C08J2400/26—Elastomers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/10—Homopolymers or copolymers of propene
    • C08J2423/12—Polypropene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/16—Ethene-propene or ethene-propene-diene copolymers

Definitions

  • the present invention relates to a thermoplastic resin foam and a foam sealing material.
  • resin foam has been used as a gasket material for mobile phones and portable information terminals.
  • the resin foam include a low-foam urethane resin foam of fine cells having an open-cell structure, a compression-molded high-foam urethane, and a polyethylene resin foam having closed cells and an expansion ratio of about 30 times, density A polyolefin-based resin foam (see Patent Documents 1 and 2) having a weight of 0.2 g / cm 3 or less has been proposed.
  • Such a resin foam is usually applied as a gasket material for mobile phones and portable information terminals by being processed into a predetermined shape and fixed to a predetermined part of these devices.
  • a dent may be caused by colliding with a corner of a desk, a roll core or the like, or by gripping with a fingertip, a nail, tweezers or the like.
  • Such dents in the resin foam generally recover over time.
  • the original function as the gasket material cannot be sufficiently achieved.
  • An object of the present invention is to provide a thermoplastic resin foam and a sealing material capable of realizing sufficient and rapid recovery of a dent.
  • the present inventors have made the dent recovery rate to be a predetermined value or more in the thermoplastic resin foam, or in addition to having a good thickness recovery rate.
  • the dent recovery rate By setting the dent recovery rate to a predetermined value or more, it is possible to obtain a thermoplastic resin foam that can improve the dust-proof performance effectively while being able to follow the minute clearance with flexibility. Heading The present invention has been completed.
  • the present invention includes the following inventions.
  • a thermoplastic resin foam characterized by having a dent recovery rate at 23 ° C. defined below of 50% or more. Depression recovery rate: The thermoplastic resin foam was compressed to the lowest point in the thickness direction of the foam with a jig having a blade angle of 90 degrees and maintained for 15 seconds, then the compressed state was released, and the compressed state was released 60 The ratio of the thickness of the dent after 2 seconds to the initial thickness.
  • the thermoplastic resin foam according to (1) having an average cell diameter of 10 to 200 ⁇ m and an apparent density of 0.01 to 0.20 g / cm 3 .
  • Repulsive stress at 50% compression Repulsive load when a thermoplastic resin foam is compressed to 50% of the initial thickness.
  • the thermoplastic resin foam according to any one of (1) to (3) which is obtained by decompression treatment of a thermoplastic resin composition impregnated with a high-pressure gas.
  • the thermoplastic resin foam according to (4), wherein the gas is an inert gas.
  • thermoplastic resin foam according to any one of 7).
  • Thickness recovery rate The ratio of the thickness to the initial thickness 1 second after releasing the compressed state after releasing the compressed state after compressing in the thickness direction to 20% of the initial thickness for 1 minute.
  • Strain recovery rate The ratio of the thickness to the initial thickness in the thickness direction after the compression state is released for 24 hours at a thickness of 50% with respect to the initial thickness and then the compressed state is released.
  • a foamed sealing material comprising the thermoplastic resin foam according to any one of (1) to (10) above.
  • thermoplastic resin foam capable of effectively improving dustproof performance while having flexibility and following a minute clearance.
  • FIG. 4 is a top view and a schematic cross-sectional view taken along line A-A ′ of an evaluation container for dynamic dustproof evaluation assembled with an evaluation sample. It is the schematic which shows the tumbler which set
  • thermoplastic resin foam of the present invention is a foam containing a thermoplastic resin, and is obtained by foaming and molding a thermoplastic resin composition.
  • the shape of the resin foam of this invention is not specifically limited, For example, any forms, such as a lump shape, a sheet form, and a film form, may be sufficient.
  • the resin foam of the present invention has a dent recovery rate at 23 ° C. defined below of 50% or more, preferably 52% or more, 55% or more, more preferably 60% or more, and particularly preferably 65% or more. It is.
  • the dent recovery rate is determined by compressing the thermoplastic resin foam to the lowest point in the thickness direction of the resin foam with a jig having a blade angle of 90 degrees and maintaining it for 15 seconds, then releasing the compressed state and releasing the compressed state. It is defined as the ratio of the thickness of the recessed portion after 60 seconds to the initial thickness.
  • a jig having a blade angle of 90 degrees used for evaluating the dent recovery rate has a right edge at the tip of the blade that gives a dent to the resin foam, and the length L of one side thereof is 1 to 1.
  • the thickness is about 20 mm, preferably about 5 mm, and the thickness M is about 1 to 20 cm, preferably about 5 cm.
  • the resin foam of the present invention Since the resin foam of the present invention has a dent recovery rate of 50% or more at 23 ° C., it is excellent in strain recovery. Therefore, the resin foam of the present invention can exhibit good dust resistance, in particular, good dynamic dust resistance (dustproof performance in a dynamic environment).
  • the resin foam of the present invention is assembled as a foam sealing material in the clearance of a mobile phone, a portable information terminal, etc., the resin foam is compressed by vibration and impact at the time of dropping, and the assembled clearance Even if it is deformed to a state where it is not completely closed, the dent can be recovered quickly and sufficiently, the clearance can be sufficiently closed, and the entry of foreign matter such as dust can be effectively prevented.
  • the cell structure is a closed cell structure or a semi-continuous semi-closed cell structure (a cell structure in which a closed cell structure and an open cell structure are mixed, and the ratio is not particularly limited). It is preferable that In particular, a cell structure in which the closed cell ratio of the resin foam is 50% or less, preferably 40% or less, more preferably 35% or less can be mentioned. By this range, at the time of compressive deformation when an impact is applied, air can easily escape from the resin, and sufficient shock absorption can be exhibited. Further, there is a cell structure in which the closed cell ratio of the resin foam is 10% or more, preferably 15% or more, more preferably 20% or more. With this range, the ratio of open cells can be adjusted to prevent the passage of fine particles such as dust, thereby improving the dust resistance.
  • the closed cell ratio can be measured, for example, by the method described in the examples.
  • the resin foam of the present invention further has an average cell diameter in the cell structure of 10 to 200 ⁇ m, preferably 10 to 180 ⁇ m, more preferably 10 to 150 ⁇ m, still more preferably 10 to 90 ⁇ m, and particularly preferably 20 to 80 ⁇ m. is there.
  • This average cell diameter is obtained by, for example, capturing an enlarged image of the bubble portion with a digital microscope (trade name “VH-8000”, manufactured by Keyence Corporation), and image analysis software (trade name “Win ROOF”, manufactured by Mitani Corporation). It can obtain
  • the upper limit of the average cell diameter of the foam is 200 ⁇ m or less, preferably 180 ⁇ m or less or 150 ⁇ m or less, more preferably 90 ⁇ m or less, and particularly preferably 80 ⁇ m or less, thereby improving dust resistance,
  • the light shielding property can be improved.
  • the lower limit of the average cell diameter of the foam is 10 ⁇ m or more, preferably 20 ⁇ m or more, cushioning properties (impact absorption) can be improved.
  • the resin foam of the present invention further has an apparent density of preferably 0.01 to 0.20 g / cm 3 , more preferably 0.01 to 0.15 g / cm 3 , and 0.01 to 0.10 g / cm 3 . 3 , more preferably 0.02 to 0.08 g / cm 3 .
  • apparent density preferably 0.01 to 0.20 g / cm 3 , more preferably 0.01 to 0.15 g / cm 3 , and 0.01 to 0.10 g / cm 3 . 3 , more preferably 0.02 to 0.08 g / cm 3 .
  • the resin foam of the present invention further has a repulsion stress at 50% compression at 23 ° C., defined below, of preferably 0.1 to 3.0 N / cm 2 , preferably 0.1 to 2.0 N. / Cm 2 , more preferably 0.1 to 1.7 N / cm 2 .
  • the repulsive stress at the time of 50% compression at 23 ° C. is defined as the repulsive load when the resin foam is compressed to a thickness of 50% with respect to the initial thickness at 23 ° C. as described above.
  • the resin foam of the present invention has a rebound stress at the time of 50% compression in this range, good flexibility can be exhibited. Therefore, in particular, when this resin foam is used as a foam sealing material, it is possible to exhibit followability with respect to a minute clearance. For this reason, when the resin foam of the present invention is assembled into a clearance as a foam seal material, even if the clearance is narrow, a problem due to the repulsion of the foam seal material (for example, deformation of a member or casing around the foam seal material) Occurrence of color unevenness in the image display unit, etc.) can be prevented.
  • the foam seal material for example, deformation of a member or casing around the foam seal material
  • the resin foam of the present invention has a specific dent recovery rate and a specific average cell diameter, a specific apparent density, and / or a specific repulsion stress at 50% compression at 23 ° C. As a result, it can be followed by a minute clearance, dust resistance and flexibility can be further improved, and dynamic dust resistance can be significantly improved.
  • the resin foam of the present invention further has a thickness recovery rate at 23 ° C. defined below of 50% or more (for example, 50 to 100%), preferably 65% or more (for example, 65 to 100%). More preferably, it is 70% or more (for example, 70 to 100%), and more preferably 75% or more (for example, 75 to 100%).
  • the thickness recovery rate at 23 ° C. is that when the compressed state is released after the resin foam is compressed at 23 ° C. to a thickness of 20% of the initial thickness for 1 minute. It is defined as the ratio of the thickness after 1 second to the initial thickness.
  • the resin foam of the present invention has a thickness recovery rate of 50% or more, the strain recovery property is quick, and thereby good dust resistance, particularly good dynamic dust resistance (dust protection under dynamic environment). Performance).
  • this resin foam is assembled in a clearance, for example, as a foam seal material, when the foam seal material is deformed by vibration and impact at the time of dropping, that is, the foam seal material is compressed and below the assembled clearance.
  • the film is deformed to a thickness of 5 mm, the thickness is recovered very quickly and the clearance can be filled. Thereby, the entrance of foreign matter such as dust can be prevented.
  • Resin foam of the present invention further, repulsion stress at 50% compression at -10 ° C. is preferably less than 10.0 N / cm 2, more preferably, 9N / cm 2 or less, 8N / cm 2 or less further preferably is 7N / cm 2 or less or 5N / cm 2 or less.
  • the repulsive stress at 50% compression here is defined as the same repulsive load except that the repulsive stress at 50% compression is different from that at 50 ° C. as described above.
  • the resin foam of the present invention further has a repulsion stress at 80% compression at 23 ° C. of preferably 1.0 to 9.0 N / cm 2 , more preferably 1.0 to 8 N / cm 2 , and even more preferably. Is 1.0 to 7.5 N / cm 2 .
  • the repulsive stress at the time of 80% compression here is defined as the repulsive load when the resin foam is compressed to 80% of the initial thickness at 23 ° C. as described above.
  • the resin foam of the present invention further preferably has a strain recovery rate at 23 ° C. of 75% or more, more preferably 80% or more, and still more preferably 85% or more.
  • the strain recovery rate is the ratio of the thickness 24 hours after the release of the compressed state to the initial thickness when the compressed state is released after being compressed to 50% of the initial thickness in the thickness direction for 24 hours. Is defined as
  • the resin foam of the present invention has a strain recovery rate of 75% or more, even if a load is maintained for a long time, it is excellent in recovering the subsequent strain, good dust resistance, particularly good dynamic Dustproofness (dustproofness in a dynamic environment) can be demonstrated.
  • the resin foam of the present invention has a dent recovery rate at 23 ° C., rebound stress at 50% compression at ⁇ 10 ° C., thickness recovery rate at 23 ° C., and 80% compression at 23 ° C.
  • the rebound stress and the strain recovery rate at 23 ° C. are satisfactory, it is sufficient in any temperature range with respect to the deformation of the resin foam that is normally considered.
  • the shape can be quickly recovered, and the dustproof performance under the dynamic environment intended in the present invention can be maximized.
  • sufficient light shielding properties or light leakage can be prevented.
  • the resin foam of the present invention is formed by a thermoplastic resin or a resin composition containing a thermoplastic resin.
  • the thermoplastic resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, a copolymer of ethylene and propylene, ethylene or propylene and another ⁇ -olefin (for example, butene -1, pentene-1, hexene-1, 4-methylpentene-1, etc.), ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylic ester, methacrylic) Polyolefin resins such as copolymers with acid, methacrylic acid ester, vinyl alcohol, etc.); styrene resins such as polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin); 6-nylon, 66-nylon, 12 -Polyamide
  • thermoplastic resin a polyolefin-based resin is preferable from the viewpoints of characteristics such as mechanical strength, heat resistance, and chemical resistance, and molding surfaces such as easy melt thermoforming.
  • Preferred examples of the polyolefin resin include a resin having a broad molecular weight distribution and having a shoulder on the high molecular weight side, a micro-crosslinking type resin (a slightly cross-linked type resin), a long-chain branched type resin, and the like.
  • melt tension (temperature: 210 ° C., tensile speed: 2.0 m / min, capillary: ⁇ 1 mm ⁇ 10 mm from the viewpoint of obtaining a resin foam having a high foaming ratio and a uniform cell structure. ) Is preferably 3 to 50 cN (preferably 8 to 50 cN).
  • the thermoplastic resin includes a rubber component and / or a thermoplastic elastomer component. Since the rubber component and the thermoplastic elastomer component have, for example, a glass transition temperature of room temperature or lower (for example, 20 ° C. or lower), flexibility and shape followability when a resin foam is obtained are extremely good.
  • the rubber component and the thermoplastic elastomer component are not particularly limited as long as they have rubber elasticity and can be foamed.
  • natural or natural rubber polyisobutylene, polyisoprene, chloroprene rubber, butyl rubber, nitrile butyl rubber, or the like Synthetic rubbers; Ethylene-propylene copolymers, ethylene-propylene-diene copolymers, ethylene-vinyl acetate copolymers, polybutenes, olefinic elastomers such as chlorinated polyethylene; styrene-butadiene-styrene copolymers, styrene-isoprene -Styrene elastomers such as styrene copolymers and hydrogenated products thereof; polyester elastomers; polyamide elastomers; various thermoplastic elastomers such as polyurethane elastomers. You may use these individually or in combination
  • an olefin elastomer is preferable as the rubber component and / or the thermoplastic elastomer component.
  • the olefin elastomer has good compatibility with the polyolefin resin exemplified as the thermoplastic resin.
  • the olefin-based elastomer may be a type having a structure in which the resin component A (olefin-based resin component A) and the rubber component B are microphase-separated, or the resin component A and the rubber component B are physically dispersed.
  • the resin component A and the rubber component B may be dynamically heat treated in the presence of a cross-linking agent (dynamic cross-linkable thermoplastic elastomer, TPV).
  • TPV dynamic cross-linkable thermoplastic elastomer
  • TPV dynamically crosslinked thermoplastic olefin elastomer
  • Dynamically-crosslinked thermoplastic olefin elastomer has higher elastic modulus and smaller compression set than TPO (non-crosslinked thermoplastic olefin elastomer). Thereby, the recoverability is good, and when the resin foam is used, the excellent recoverability is exhibited.
  • the dynamically crosslinked thermoplastic olefin elastomer is a mixture containing the resin component A (olefin resin component A) forming a matrix and the rubber component B forming a domain, in the presence of a crosslinking agent. It is a multiphase polymer having a sea-island structure in which crosslinked rubber particles are finely dispersed as domains (island phases) in the resin component A, which is a matrix (sea phase), obtained by dynamic heat treatment.
  • thermoplastic olefin elastomer examples include, for example, JP 2000-007858 A, JP 2006-052277 A, JP 2012-072306 A, JP 2012-056768 A, JP-A-2010-241897, JP-A-2009-0697969, RE-list 03/002654, etc., “Zeotherm” (manufactured by Zeon Corporation), “Thermorun” (manufactured by Mitsubishi Chemical Corporation), “Surlink” 3245D "(manufactured by Toyobo Co., Ltd.) and the like.
  • the content is not particularly limited.
  • the ratio of the thermoplastic resin to the rubber component and / or the thermoplastic elastomer component in the resin constituting the resin foam of the present invention is preferably 70/30 to 30/70, more preferably on a weight basis. Is 60/40 to 30/70, even more preferably 50/50 to 30/70, even more preferably 60/40 to 10/90, 58/42 to 10/90, 55/45 to 10/90.
  • the ratio of the rubber component and / or the thermoplastic elastomer component is too small, the cushioning property of the resin foam tends to be lowered or the recoverability after compression may be lowered.
  • the rubber component and / or the thermoplastic elastomer component If the ratio is too large, outgassing tends to occur during foam formation, and it may be difficult to obtain a highly foamable foam.
  • the resin foam of the present invention is excellent in so-called rubber elasticity in order to realize flexibility at high compression and shape recovery after compression, that is, to enable large deformation and prevent plastic deformation. Suitable materials are suitable. From this viewpoint, the resin foam of the present invention preferably contains a rubber component and / or a thermoplastic elastomer component together with the above-described thermoplastic resin as the constituent resin composition.
  • the resin foam of the present invention preferably further contains a nucleating agent in the constituent resin composition.
  • a nucleating agent in the constituent resin composition.
  • nucleating agent examples include oxides and composite oxides such as talc, silica, alumina, zeolite, calcium carbonate, magnesium carbonate, barium sulfate, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, mica, and montmorillonite.
  • a nucleating agent is used individually or in combination of 2 or more types.
  • the average particle size of the nucleating agent is not particularly limited, but is preferably 0.3 to 1.5 ⁇ m, more preferably 0.4 to 1.2 ⁇ m. By setting it as such an average particle diameter, sufficient function as a nucleating agent can be exhibited. In addition, a high expansion ratio can be realized without the nucleating agent breaking through the cell walls.
  • This average particle diameter can be measured by a laser diffraction particle size distribution measuring method. For example, the measurement can be performed from the sample dispersion dilution (AUTO measurement mode) using “MICROTRAC MT-3000” manufactured by LEEDS & NORTHRUP INSTRUMENTS.
  • the content when a nucleating agent is included is not particularly limited, but is preferably 0.5 to 150 parts by weight, more preferably 2 to 140 parts by weight with respect to 100 parts by weight of the constituent resin. Part by weight, still more preferably 3 to 130 parts by weight.
  • the resin foam of this invention is comprised with a thermoplastic resin and is easy to burn, it is preferable to contain a flame retardant.
  • a flame retardant a non-halogen-nonantimony inorganic flame retardant is preferable.
  • inorganic flame retardants include metal hydroxides and hydrates of metal compounds. More specifically, aluminum hydroxide; magnesium hydroxide; hydrates of magnesium oxide and nickel oxide; hydrates of magnesium oxide and zinc oxide, and the like. Among these, magnesium hydroxide is preferable.
  • the hydrated metal compound may be surface-treated.
  • a flame retardant is used individually or in combination of 2 or more types.
  • the content is preferably 5 to 70 parts by weight, more preferably 25 to 65 parts by weight with respect to 100 parts by weight of the constituent resin.
  • the resin foam of the present invention further has a polar functional group, a melting point of 50 to 150 ° C., and contains at least one aliphatic compound selected from fatty acids, fatty acid amides, and fatty acid metal soaps. Also good. Of these, fatty acids and fatty acid amides are preferred.
  • Such an aliphatic compound When such an aliphatic compound is contained in the resin foam of the present invention, the cell structure is less likely to collapse during processing (particularly punching processing), shape recovery is improved, and workability (particularly, (Punching workability) is further improved.
  • Such an aliphatic compound has high crystallinity, and when added to the thermoplastic resin (especially polyolefin resin), a strong film is formed on the resin surface, and the wall surfaces of the bubbles forming the cell structure block each other. This is presumed to have a function to prevent the above.
  • Such aliphatic compounds particularly those containing a highly polar functional group, are difficult to be compatible with polyolefin resins, so that they easily precipitate on the surface of the resin foam and exhibit the above effects.
  • Cheap is difficult to be compatible with polyolefin resins, so that they easily precipitate on the surface of the resin foam and exhibit the above effects.
  • the melting point of the aliphatic compound is preferably 50 to 50 from the viewpoints of lowering the molding temperature when foam-molding the resin composition, suppressing deterioration of the resin (particularly polyolefin resin), imparting sublimation resistance, and the like. 150 ° C., more preferably 70 to 100 ° C.
  • the fatty acid preferably has about 18 to 38 carbon atoms, more preferably about 18 to 22 carbon atoms.
  • stearic acid, behenic acid, 12-hydroxystearic acid and the like can be mentioned. Of these, behenic acid is particularly preferable.
  • the fatty acid amide is preferably a fatty acid moiety having about 18 to 38 carbon atoms, more preferably 18 to 22 carbon atoms.
  • either monoamide or bisamide may be used.
  • Specific examples include stearic acid amide, oleic acid amide, erucic acid amide, methylene bis stearic acid amide, and ethylene bis stearic acid amide. Of these, erucic acid amide is particularly preferable.
  • fatty acid metal soap examples include aluminum, calcium, magnesium, lithium, barium, zinc and lead salts of the above fatty acids.
  • the content when such an aliphatic compound is included is not particularly limited, but is preferably 1 to 5 parts by weight, more preferably 100 parts by weight of the resin constituting the resin foam. 1.5 to 3.5 parts by weight, still more preferably 2 to 3 parts by weight.
  • a foaming agent for example, an inert gas such as carbon dioxide and nitrogen
  • the resin foam of the present invention may contain a lubricant. Thereby, while improving the fluidity
  • a lubricant is used individually or in combination of 2 or more types.
  • the lubricant is not particularly limited.
  • hydrocarbon lubricants such as liquid paraffin, paraffin wax, microwax and polyethylene wax; butyl stearate, monoglyceride stearate, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate And ester lubricants.
  • content of a lubricant can be suitably selected in the range which does not impair the effect of this invention.
  • the resin foam of the present invention may contain other additives as necessary.
  • additives include anti-shrinkage agents, anti-aging agents, heat stabilizers, light stabilizers such as HALS, weathering agents, metal deactivators, ultraviolet absorbers, light stabilizers, copper damage inhibitors, and the like.
  • Stabilizers antibacterial agents, fungicides, dispersants, tackifiers, colorants such as carbon black and organic pigments, fillers, and the like.
  • a composition containing an additive for example, a colorant such as carbon black, a softening agent, etc.
  • additives are used alone or in combination of two or more. The content of these additives can be appropriately selected within a range that does not impair the effects of the present invention.
  • the resin foam of the present invention is obtained by mixing and kneading a thermoplastic resin (including a rubber component and / or a thermoplastic elastomer component) and optionally an additive such as a nucleating agent, an aliphatic compound, or a lubricant. It can manufacture by foaming and shape
  • the foaming method used when foaming and molding the resin composition is not particularly limited, and examples thereof include usually used methods such as a physical method and a chemical method.
  • a general physical method is a method of forming bubbles by dispersing a low boiling point liquid (foaming agent) such as chlorofluorocarbons or hydrocarbons in a resin, and then heating to volatilize the foaming agent.
  • a general chemical method is a method in which bubbles are formed by a gas generated by thermal decomposition of a compound (foaming agent) added to a resin.
  • a method using a high-pressure gas as a foaming agent is preferable because a foam having a small cell diameter and a high cell density can be easily obtained.
  • a method using a high-pressure inert gas as a foaming agent is preferable.
  • a method of using a high-pressure gas as a foaming agent a method in which a resin composition is impregnated with a high-pressure gas and then subjected to a pressure reduction process is preferable.
  • the inert gas is not particularly limited as long as it is inert and can be impregnated into the resin that is the material of the resin foam, and examples thereof include carbon dioxide, nitrogen, and air. These gases may be mixed and used. Of these, carbon dioxide or nitrogen is preferred, and carbon dioxide is more preferred because the amount of impregnation into the resin is large and the impregnation speed is fast.
  • the high-pressure gas (particularly inert gas, and further carbon dioxide) is preferably a gas in a supercritical state.
  • the solubility of the gas in the resin is increased and high concentration can be mixed.
  • the generation of bubble nuclei increases, and the density of bubbles formed by the growth of the bubble nuclei has a porosity. Even if they are the same, they become larger, so that fine bubbles can be obtained.
  • carbon dioxide has a critical temperature of 31 ° C. and a critical pressure of 7.4 MPa.
  • an unfoamed resin molded product (unfoamed resin molded product) is obtained by molding a resin composition into an appropriate shape such as a sheet shape in advance. After that, the unfoamed resin molded body is impregnated with a high-pressure gas and foamed by releasing the pressure, and the resin composition is kneaded with the high-pressure gas under pressure, and simultaneously molded and pressurized. Any of the continuous methods of releasing and simultaneously performing molding and foaming may be used.
  • the resin composition is an extruder such as a single screw extruder or a twin screw extruder. Molding method using a kneading machine equipped with blades such as rollers, cams, kneaders, Banbury molds, etc., and then kneading the resin composition to a predetermined thickness using a hot plate press or the like And a method of molding the resin composition using an injection molding machine.
  • the unfoamed resin molded body can be formed by other molding methods besides extrusion molding, press molding, and injection molding.
  • the shape of the unfoamed resin molded body is not particularly limited, and various shapes can be selected depending on the application, and examples thereof include a sheet shape, a roll shape, a plate shape, and a lump shape.
  • the resin composition can be molded by an appropriate method that can obtain an unfoamed resin molded body having a desired shape and thickness.
  • the obtained unfoamed resin molded product is placed in a pressure vessel (high pressure vessel) and injected with high pressure gas (especially inert gas or even carbon dioxide) ( Gas) impregnating a non-foamed resin molded body with a high-pressure gas, releasing the pressure when the sufficiently high-pressure gas is impregnated (usually up to atmospheric pressure), and creating bubble nuclei in the resin Bubbles are formed in the resin through a decompression step to be generated, and in some cases (if necessary), a heating step in which bubble nuclei are grown by heating. Bubble nuclei may be grown at room temperature without providing a heating step.
  • high pressure gas especially inert gas or even carbon dioxide
  • the resin composition is kneaded using an extruder such as a single screw extruder or a twin screw extruder while a high pressure gas (especially an inert gas, Is injected (introduced) carbon dioxide), and the pressure is released by extruding the resin composition through a kneading impregnation step for impregnating the resin composition with a sufficiently high pressure gas, a die provided at the tip of the extruder ( Usually, up to atmospheric pressure), foaming or molding may be performed by a molding decompression step in which molding and foaming are performed simultaneously.
  • an extruder such as a single screw extruder or a twin screw extruder while a high pressure gas (especially an inert gas, Is injected (introduced) carbon dioxide), and the pressure is released by extruding the resin composition through a kneading impregnation step for impregnating the resin composition with a sufficiently high pressure gas, a die provided at the tip of the ex
  • an injection molding machine or the like may be used in addition to the extruder.
  • a heating step for growing bubbles by heating may be provided as necessary.
  • the shape may be fixed rapidly by cooling with cold water or the like.
  • the high-pressure gas may be introduced continuously or discontinuously.
  • known methods such as a water bath, an oil bath, a hot roll, a hot air oven, a far infrared ray, a near infrared ray, and a microwave can be employed.
  • the stretching is preferably performed so that the ratio of the resin extrusion speed and the molding speed is 1: 1.2 to 5.
  • the ratio of the resin extrusion speed and the molding speed is 1: 1.2 to 5.
  • the molding speed means a speed at which the resin sheet is fed by a roll or a belt.
  • the molding speed is not particularly limited, and is preferably 2 to 100 m / min, for example. Thereby, a resin sheet can be shape
  • the nip pressure is preferably set so that the foam is not crushed in the thickness direction.
  • the mixing amount of the gas at the time of foaming or molding the resin composition is not particularly limited. For example, it is preferably 2 to 10% by weight, more preferably 2.5 to 2.5%, based on the total amount of the resin components in the resin composition. 8% by weight, still more preferably 3-6% by weight. By setting it as this range, a foam with a high foaming rate can be obtained, without gas separating in a molding machine.
  • the pressure when impregnating the unfoamed resin molded product or the resin composition with the gas in the gas impregnation step in the batch method or the kneading impregnation step in the continuous method when foaming and molding the resin composition can be appropriately selected in consideration of the type of gas and operability.
  • the pressure is preferably 6 MPa or more (for example, 6 to 100 MPa), more preferably 8 MPa or more (for example, 8 to 100 MPa).
  • the temperature when impregnating the non-foamed resin molded product or resin composition with the high-pressure gas is the gas or resin used. It depends on the type. This temperature can be selected within a wide range, and is preferably 10 to 350 ° C. in consideration of operability and the like.
  • the impregnation temperature when impregnating a sheet-like unfoamed resin molded body with a high-pressure gas is preferably 10 to 250 ° C., more preferably 40 to 240 ° C., and even more preferably 60 to 230 ° C.
  • the temperature at which high-pressure gas is injected into the resin composition and kneaded is preferably 60 to 350 ° C., more preferably 100 to 320 ° C., and even more preferably 150 to 300 ° C.
  • the temperature during impregnation is preferably 32 ° C. or higher (particularly 40 ° C. or higher) in order to maintain a supercritical state.
  • the pressure reduction rate in the pressure reduction step when foaming and molding the resin composition in a batch method or a continuous method is not particularly limited, but is preferably 5 to 300 MPa / second in order to obtain uniform fine bubbles.
  • the heating temperature in the heating step is, for example, 40 to 250 ° C. (preferably 60 to 250 ° C.).
  • a highly foamed resin foam can be produced, and a thick resin foam can be produced.
  • the gap between the dies attached to the tip of the extruder is as narrow as possible (usually 0.1 to 1 in order to maintain the pressure inside the extruder in the kneading impregnation step. About 0 mm). Therefore, in order to obtain a thick resin foam, it is preferable to foam the resin composition extruded through a narrow gap at a high magnification.
  • the thickness of the formed resin foam is limited to a thin one (for example, 0.5 to 2.0 mm).
  • a resin foam having a thickness of 0.50 to 5.00 mm can be continuously obtained by foaming or molding a resin composition using a high-pressure gas. It is.
  • the resin foam of the present invention has a dent recovery rate, a thickness recovery rate, a strain recovery rate, an average cell diameter, a repulsion stress during compression, an apparent density, a relative density, and the like, a gas, a thermoplastic resin, a rubber component, and / or a heat.
  • operating conditions such as temperature, pressure and time in the gas impregnation process and kneading impregnation process
  • operating conditions such as the decompression speed, temperature and pressure in the decompression process and molding decompression process, after decompression Or it can also adjust by selecting and setting suitably the heating temperature etc. in the heating process after shaping
  • the resin foam of the present invention is decompressed after impregnating a resin composition containing at least a nucleating agent and an aliphatic compound in addition to a thermoplastic resin with a high-pressure gas (particularly an inert gas). It is preferably formed through a process.
  • a resin composition containing at least a nucleating agent and an aliphatic compound in addition to a thermoplastic resin with a high-pressure gas (particularly an inert gas). It is preferably formed through a process.
  • a high-pressure gas particularly an inert gas
  • the resin foam of the present invention is obtained by impregnating a supercritical inert gas with a resin composition containing at least a nucleating agent having a particularly small average particle diameter and an aliphatic compound in addition to a thermoplastic resin. More preferably, it is formed through a pressure reducing step.
  • the average cell diameter is extremely small, the cell structure ratio is low, the cell structure is high, the foaming ratio is high, the flexibility is good, the cell structure is difficult to deform or compress, and the strain when pressed It has excellent recoverability and can further suppress the nucleating agent from breaking through the bubble wall. Therefore, the resin foam which is more excellent in workability can be obtained easily.
  • the resin foam of the present invention is a mixture of a thermoplastic resin and a rubber component and / or a thermoplastic elastomer component, the ratio of which is 70/30 to 30/70 on a weight basis,
  • the foam sealing material of this invention is a member containing the said resin foam.
  • the shape of the foam sealing material is not particularly limited, and a sheet shape (including a film shape) is preferable.
  • the foamed sealing material may be configured only by a resin foam, or may be configured such that an adhesive layer, a base material layer, and the like are laminated on the resin foam.
  • the foamed sealing material of the present invention preferably has an adhesive layer.
  • the foamed sealing material of the present invention when it is a sheet-like foamed sealing material, it may have an adhesive layer on one or both sides.
  • a processing mount can be provided on the foamed sealing material via the adhesive material layer, and further, fixed to the adherend, temporarily fixed, etc. it can.
  • the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited.
  • an acrylic pressure-sensitive adhesive such as a rubber-based pressure-sensitive adhesive (such as a natural rubber-based pressure-sensitive adhesive, a synthetic rubber-based pressure-sensitive adhesive), a silicone-based pressure-sensitive adhesive, or a polyester-based pressure-sensitive adhesive.
  • Known pressure-sensitive adhesives such as adhesives, urethane-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives can be appropriately selected and used.
  • An adhesive can be used individually or in combination of 2 or more types.
  • the pressure-sensitive adhesive may be any type of pressure-sensitive adhesive such as an emulsion-based pressure-sensitive adhesive, a solvent-based pressure-sensitive adhesive, a hot-melt pressure-sensitive adhesive, an oligomer-based pressure-sensitive adhesive, and a solid-type pressure-sensitive adhesive.
  • an acrylic pressure-sensitive adhesive is preferable from the viewpoint of preventing contamination of the adherend.
  • the thickness of the adhesive material layer is preferably 2 to 100 ⁇ m, more preferably 10 to 100 ⁇ m.
  • the pressure-sensitive adhesive layer may have any form of a single layer or a laminate, and may be foamable or non-foamable. Of these, a non-foaming pressure-sensitive adhesive layer is preferable.
  • the pressure-sensitive adhesive layer may be provided via another layer (lower layer).
  • a lower layer include other pressure-sensitive adhesive layers, intermediate layers, undercoat layers, base material layers (particularly film layers, nonwoven fabric layers, etc.) and the like.
  • the lower layer may be a foamable layer or a porous layer, but is preferably a non-foamable layer, more preferably a resin layer.
  • the pressure-sensitive adhesive layer may be protected by a release film (separator) (for example, release paper, release film, etc.).
  • the foamed sealing material of the present invention contains the resin foam of the present invention, it has good dust resistance, particularly good dynamic dust resistance, and has flexibility to follow a minute clearance.
  • the foamed sealing material of the present invention may be processed so as to have a desired shape and thickness.
  • various shapes may be processed according to the device, equipment, casing, member, and the like used.
  • the foamed sealing material of the present invention is suitably used as a member used when various members or parts are attached (attached) to a predetermined site.
  • the foamed sealing material of the present invention is suitable as a member used when attaching (attaching) a component constituting an electric or electronic device to a predetermined site in an electric or electronic device.
  • the various members or parts that can be attached (mounted) using the foamed member are not particularly limited, and examples thereof include various members or parts in electrical or electronic equipment.
  • Examples of such a member or component for electric or electronic equipment include an image display member (display unit) (particularly a small image display member) mounted on an image display device such as a liquid crystal display, an electroluminescence display, or a plasma display. ), Optical members or optical components such as cameras and lenses (particularly small cameras and lenses) mounted on mobile communication devices such as so-called “mobile phones” and “portable information terminals”.
  • the foamed sealing material of the present invention is preferably used around the display unit such as an LCD (liquid crystal display) and the display unit such as an LCD (liquid crystal display) and a housing for the purpose of dust prevention, light shielding, buffering, and the like. What is inserted and used between a body (window part) is mentioned.
  • the foamed sealing material of the present invention is attached to such a member or part, it is preferably attached so as to close the clearance.
  • the clearance is not particularly limited, and may be about 0.05 to 0.5 mm, for example.
  • the thermoplastic resin foam and foamed sealing material of the present invention will be described based on examples.
  • Example 1 As a resin composition, 35 parts by weight of polypropylene, 60 parts by weight of a thermoplastic elastomer composition, 5 parts by weight of lubricant, Ten parts by weight of the nucleating agent and 2 parts by weight of erucic acid amide (melting point: 80 to 85 ° C.) were kneaded at a temperature of 200 ° C. with a twin-screw kneader.
  • Polypropylene is a resin having a melt flow rate (MFR) of 0.35 g / 10 min
  • MFR melt flow rate
  • the thermoplastic elastomer composition contains 15.0% by weight of carbon black and is a blend of polypropylene (PP) and ethylene / propylene / 5-ethylidene-2-norbornene terpolymer (EPT) (crosslinked olefin type).
  • Thermoplastic elastomer, TPV), polypropylene: ethylene / propylene / 5-ethylidene-2-norbornene terpolymer 25: 75 (weight basis),
  • the lubricant is a master batch in which 1 part by weight of stearic acid monoglyceride is blended with 10 parts by weight of polyethylene,
  • the nucleating agent is magnesium hydroxide having an average particle size of 0.8 ⁇ m.
  • the resin composition was extruded into strands, cooled with water, cut into pellets, and molded.
  • This pellet was put into a tandem type single screw extruder manufactured by Nippon Steel Works Co., Ltd., and 3.8% by weight of carbon dioxide gas was injected under an atmosphere of 220 ° C. under a pressure of 14 (18 after injection) MPa. Carbon dioxide gas was sufficiently saturated and cooled to a temperature suitable for foaming. Thereafter, the resin was extruded from a die, and the ratio of the resin extrusion speed to the molding speed was adjusted to be in the range of 1: 1.2 to 2 to obtain a resin foam (sheet-like). This resin foam had a semi-continuous semi-closed cell structure with a closed cell rate of 32%.
  • Example 2 A resin foam (sheet-like) was obtained in the same manner as in Example 1 except that 3.7% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
  • Example 3 A resin foam (sheet-like) was obtained in the same manner as in Example 1 except that 3.5% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
  • TPO polypropylene
  • EPT ethylene / propylene / 5-ethylidene-2-norbornene terpolymer
  • the resin composition was extruded into a strand shape, cooled with water, cut into a pellet shape, and molded.
  • This pellet was put into a tandem type single screw extruder manufactured by Nippon Steel Works Co., Ltd., and 3.8% by weight of carbon dioxide gas was injected under an atmosphere of 220 ° C. under a pressure of 14 (18 after injection) MPa. Carbon dioxide gas was sufficiently saturated and cooled to a temperature suitable for foaming. Then, it extruded from the die
  • This resin foam had a semi-continuous semi-closed cell structure with a closed cell ratio of 46%.
  • Comparative Example 2 A resin foam (sheet-like) was obtained in the same manner as in Comparative Example 1 except that 3.7% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
  • the closed cell ratio of the resin foams obtained in Examples and Comparative Examples was measured according to the following method. From the obtained resin foam, a flat square test piece having a constant thickness and a side of 5 cm is cut out. Subsequently, the weight W 1 (g) and thickness (cm) of the test piece are measured, and the apparent volume V 1 (cm 3 ) of the test piece is calculated. Next, the obtained value is substituted into the equation (1), and the apparent volume V 2 (cm 3 ) occupied by the bubbles is calculated. The density of the resin constituting the test piece is ⁇ g / cm 3 .
  • a smooth cross section was created by cutting the resin foam in a direction perpendicular to the main surface of the resin foam (thickness direction) in parallel with the direction perpendicular to the MD direction (flow direction) of the resin foam. These cross-sections are taken with a digital microscope (trade name “VHX-500”, manufactured by Keyence Corporation), and an enlarged image of the foam of the resin foam is captured. Analysis software for the measuring instrument (Mitani Corporation, Win ROOF) The average cell diameter ( ⁇ m) was determined by image analysis using The number of bubbles in the captured enlarged image is about 200, and the average of these 200 was used.
  • the resin foam was compressed at 23 ° C. to a thickness of 50% of the initial thickness for 24 hours, and after releasing the compressed state, the ratio was set to the initial thickness in the thickness direction for 24 hours.
  • the resin foam was punched into a frame shape (window frame shape) (40 mm ⁇ 56 mm, width: 2 mm) shown in FIG.
  • This evaluation sample 22 was attached to the dynamic dustproof evaluation container 2 shown in FIG.
  • the compression rate of the evaluation sample 22 at the time of mounting was 50% in the thickness direction with respect to the initial thickness.
  • the evaluation sample 22 is fixed to the base plate 24 with a black acrylic plate 211 attached to the base plate 24 via a foam compression plate 27 by screws 26, and fixed on the aluminum spacer 23. It is provided between the black acrylic board 212 arrange
  • the compression rate of the evaluation sample 22 can be adjusted by adjusting the thickness of the aluminum spacer 23.
  • the evaluation container 2 to which the evaluation sample 22 is attached has a system in which a certain internal space 29 is closed by the evaluation sample 22.
  • the evaluation container 2 is configured as a powder supply unit that is positioned adjacent to the outside of the evaluation sample 22 and in which a constant external space 25 is closed between the evaluation sample 22 and the foam compression plate 27.
  • the external space 25 is filled with 0.1 g of powdered dust (for example, a starch having a particle diameter of 17 ⁇ m).
  • powdered dust for example, a starch having a particle diameter of 17 ⁇ m.
  • the package was disassembled.
  • grains which passed the sample 22 for evaluation from the external space 25 which is a powder supply part, and were made to function as the upper and lower walls of internal space were attached to the digital microscope (device) Name “VHX-600” (manufactured by Keyence Corporation). Still images are created for the black acrylic plate 211 and the black acrylic plate 212, and binarization processing is performed using image analysis software (software name “Win ROOF”, manufactured by Mitani Corp.), and the number of particles of the starch is counted. did. The observation was performed in a clean bench to reduce the influence of airborne dust.
  • the present invention is useful as an internal insulator for electronic devices, cushioning materials, sound insulating materials, dustproof materials, shock absorbing materials, light shielding materials, heat insulating materials, food packaging materials, clothing materials, building materials, etc., cushioning properties and strain recovery Resin foam and foam sealing material with excellent foaming ratio and high foaming ratio, especially around the display part of mobile phones, portable information terminals, LCDs, etc. ) Can be widely used for various members.

Abstract

The purpose of the present invention is to provide a thermoplastic resin foam and a foam sealant that enable indentations to be sufficiently and rapidly restored. The thermoplastic resin foam is characterized in that the indentation recovery rate defined below is at least 50%, and the foam sealant is characterized by containing the thermoplastic resin foam (in particular, it is preferable an adhesive layer positioned on one or both sides of the thermoplastic resin foam be provided). Indentation recovery rate: After compressing the thermoplastic resin foam at 23°C with a jig having a 90 degree blade angle to the lowest point in the thickness direction of the foam for 15 seconds, and then releasing the compressed state, the indentation recovery rate is the ratio of the thickness of the indented portion with respect to the initial thickness 60 seconds after the compressed state has been released.

Description

熱可塑性樹脂発泡体及び発泡シール材Thermoplastic resin foam and foam sealing material
　本発明は、熱可塑性樹脂発泡体及び発泡シール材に関する。 The present invention relates to a thermoplastic resin foam and a foam sealing material.
　従来から、携帯電話及び携帯型情報端末機等のガスケット材として、樹脂発泡体が使用されている。
　樹脂発泡体としては、例えば、低発泡で連続気泡構造を有する微細セルのウレタン樹脂発泡体、高発泡ウレタンを圧縮成形したもの、また独立気泡を有する発泡倍率３０倍程度のポリエチレン樹脂発泡体、密度が０．２ｇ／ｃｍ3以下のポリオレフィン系樹脂発泡体（特許文献１及び２参照）等が提案されている。 Conventionally, resin foam has been used as a gasket material for mobile phones and portable information terminals.
Examples of the resin foam include a low-foam urethane resin foam of fine cells having an open-cell structure, a compression-molded high-foam urethane, and a polyethylene resin foam having closed cells and an expansion ratio of about 30 times, density A polyolefin-based resin foam (see Patent Documents 1 and 2) having a weight of 0.2 g / cm 3 or less has been proposed.
　このような樹脂発泡体は、通常、所定の形状に加工され、これら機器等の所定の部位に固定されることにより、携帯電話及び携帯型情報端末機等ガスケット材として適用される。
　しかし、このような加工及び取り付けの際に、机の角、ロール芯等に衝突して、あるいは、指先及び爪、ピンセット等で把持することにより凹みが生じることがあった。
　このような樹脂発泡体における凹みは、一般に時間の経過とともに回復する。その一方で、凹みの回復に長時間を要する、あるいは凹みの回復自体が不十分であるなどの場合には、ガスケット材としての本来の機能を十分果たさせることができない。 Such a resin foam is usually applied as a gasket material for mobile phones and portable information terminals by being processed into a predetermined shape and fixed to a predetermined part of these devices.
However, in such processing and attachment, a dent may be caused by colliding with a corner of a desk, a roll core or the like, or by gripping with a fingertip, a nail, tweezers or the like.
Such dents in the resin foam generally recover over time. On the other hand, when it takes a long time to recover the dent, or when the dent recovery itself is insufficient, the original function as the gasket material cannot be sufficiently achieved.
　特に、近年の携帯電話及び携帯型情報端末機等の小型・薄型、画像表示部の大型化又は高機能化（情報入力機能としてのタッチパネル機能の搭載等）の要請等により、これら機器が動的環境下で使用されることが多いため、凹みの十分かつ迅速な回復を実現して、凹みに起因するごみの侵入、光漏れ等の不具合の発生を防止することができる特性が強く求められている。また、小型・薄型の携帯電話及び携帯型情報端末機等の微小なクリアランスに追従させることができる柔軟性をも有することが求められている。 In particular, due to recent demands for small and thin mobile phones and portable information terminals, etc., large-scale or high-functionality image display units (equipment of touch panel functions as information input functions, etc.) Because it is often used in an environment, there is a strong demand for characteristics that can realize sufficient and quick recovery of the dent and prevent the occurrence of defects such as dust intrusion and light leakage due to the dent. Yes. In addition, it is required to have flexibility to follow a small clearance of a small and thin mobile phone and a portable information terminal.
特開２００５－２２７３９２号公報JP 2005-227392 A 特開２００７－２９１３３７号公報JP 2007-291337 A
　本発明の目的は、凹みの十分かつ迅速な回復を実現し得る熱可塑性樹脂発泡体及びシール材を提供することを目的とする。 An object of the present invention is to provide a thermoplastic resin foam and a sealing material capable of realizing sufficient and rapid recovery of a dent.
　本発明者らは、上記の問題を解決するために鋭意検討した結果、熱可塑性樹脂発泡体において、凹み回復率を所定の値以上とすること、あるいは良好な厚み回復率を有することに加えて凹み回復率を所定の値以上にすることにより、柔軟性を備えて微小なクリアランスへの追従を可能としながら、効果的に防塵性能を向上させることができる熱可塑性樹脂発泡体が得られることを見出し本発明の完成に至った。 As a result of intensive studies to solve the above problems, the present inventors have made the dent recovery rate to be a predetermined value or more in the thermoplastic resin foam, or in addition to having a good thickness recovery rate. By setting the dent recovery rate to a predetermined value or more, it is possible to obtain a thermoplastic resin foam that can improve the dust-proof performance effectively while being able to follow the minute clearance with flexibility. Heading The present invention has been completed.
　本発明は、以下の発明を含む。
　（１）下記で定義される２３℃での凹み回復率が５０％以上であることを特徴とする熱可塑性樹脂発泡体。
　凹み回復率：熱可塑性樹脂発泡体を、刃角９０度の治具によって、前記発泡体の厚み方向の最下点まで圧縮して１５秒間維持した後、圧縮状態を解除し、圧縮状態解除６０秒後の凹み部分の厚みの初期厚みに対する割合。
　（２）平均セル径が１０～２００μｍであり、見掛け密度が０．０１～０．２０ｇ／ｃｍ3である（１）記載の熱可塑性樹脂発泡体。
　（３）下記で定義される２３℃での５０％圧縮時の反発応力が０．１～３．０Ｎ／ｃｍ2である（１）又は（２）記載の熱可塑性樹脂発泡体。
　５０％圧縮時の反発応力：熱可塑性樹脂発泡体を、初期厚みに対して５０％の厚みに圧縮した際の対反発荷重。
　（４）高圧ガスが含浸された熱可塑性樹脂組成物の減圧処理によって得られる（１）～（３）のいずれか１つに記載の熱可塑性樹脂発泡体。
　（５）前記ガスが、不活性ガスである（４）記載の熱可塑性樹脂発泡体。
　（６）前記不活性ガスが、二酸化炭素又は窒素である（５）記載の熱可塑性樹脂発泡体。
　（７）前記ガスが、超臨界状態のガスである（４）～（６）のいずれか１つに記載の熱可塑性樹脂発泡体。
　（８）下記で定義される２３℃での厚み回復率が５０％以上であり、かつ－１０℃での５０％圧縮時の反発応力が１０．０Ｎ／ｃｍ2未満である（１）～（７）のいずれか１つに記載の熱可塑性樹脂発泡体。
　厚み回復率：厚み方向に、初期厚みに対して２０％の厚みに１分間圧縮した後、圧縮状態を解除し、圧縮状態解除１秒後の厚みの初期厚みに対する割合。
　（９）２３℃での８０％圧縮時の反発応力が１．０～９．０Ｎ／ｃｍ2である（１）～（８）のいずれか１つに記載の熱可塑性樹脂発泡体。
　（１０）下記で定義される２３℃での歪回復率が７５％以上である（１）～（９）のいずれか１つに記載の熱可塑性樹脂発泡体。
　歪回復率：厚み方向に、初期厚みに対して５０％の厚みでに２４時間圧縮した後、圧縮状態を解除し、圧縮状態解除２４時間後の厚みの初期厚みに対する割合。
　（１１）上記（１）～（１０）のいずれか１つに記載の熱可塑性樹脂発泡体を含むことを特徴とする発泡シール材。
　（１２）熱可塑性樹脂発泡体の片面又は両面に配置された粘着材層を備える（１１）の発泡シール材。
　（１３）粘着材層が、フィルム層を介して、熱可塑性樹脂発泡体表面に配置されている（１２）の発泡シール材。 The present invention includes the following inventions.
(1) A thermoplastic resin foam characterized by having a dent recovery rate at 23 ° C. defined below of 50% or more.
Depression recovery rate: The thermoplastic resin foam was compressed to the lowest point in the thickness direction of the foam with a jig having a blade angle of 90 degrees and maintained for 15 seconds, then the compressed state was released, and the compressed state was released 60 The ratio of the thickness of the dent after 2 seconds to the initial thickness.
(2) The thermoplastic resin foam according to (1), having an average cell diameter of 10 to 200 μm and an apparent density of 0.01 to 0.20 g / cm 3 .
(3) The thermoplastic resin foam according to (1) or (2), wherein the rebound stress at 50% compression at 23 ° C. defined below is 0.1 to 3.0 N / cm 2 .
Repulsive stress at 50% compression: Repulsive load when a thermoplastic resin foam is compressed to 50% of the initial thickness.
(4) The thermoplastic resin foam according to any one of (1) to (3), which is obtained by decompression treatment of a thermoplastic resin composition impregnated with a high-pressure gas.
(5) The thermoplastic resin foam according to (4), wherein the gas is an inert gas.
(6) The thermoplastic resin foam according to (5), wherein the inert gas is carbon dioxide or nitrogen.
(7) The thermoplastic resin foam according to any one of (4) to (6), wherein the gas is a gas in a supercritical state.
(8) The thickness recovery rate at 23 ° C. defined below is 50% or more, and the rebound stress at 50% compression at −10 ° C. is less than 10.0 N / cm 2 (1) to ( The thermoplastic resin foam according to any one of 7).
Thickness recovery rate: The ratio of the thickness to the initial thickness 1 second after releasing the compressed state after releasing the compressed state after compressing in the thickness direction to 20% of the initial thickness for 1 minute.
(9) The thermoplastic resin foam according to any one of (1) to (8), wherein the repulsive stress at 80% compression at 23 ° C. is 1.0 to 9.0 N / cm 2 .
(10) The thermoplastic resin foam according to any one of (1) to (9), wherein the strain recovery rate at 23 ° C. defined below is 75% or more.
Strain recovery rate: The ratio of the thickness to the initial thickness in the thickness direction after the compression state is released for 24 hours at a thickness of 50% with respect to the initial thickness and then the compressed state is released.
(11) A foamed sealing material comprising the thermoplastic resin foam according to any one of (1) to (10) above.
(12) The foam sealing material according to (11), comprising an adhesive material layer disposed on one or both surfaces of the thermoplastic resin foam.
(13) The foamed sealing material according to (12), wherein the adhesive material layer is disposed on the surface of the thermoplastic resin foam via the film layer.
　本発明によれば、柔軟性を備えて微小なクリアランスへの追従を可能としながら、効果的に防塵性能を向上させることができる熱可塑性樹脂発泡体を提供することができる。 According to the present invention, it is possible to provide a thermoplastic resin foam capable of effectively improving dustproof performance while having flexibility and following a minute clearance.
本発明の熱可塑性樹脂発泡体の凹み回復率の評価に用いる治具の形状を説明するための治具の正面図及び側面図である。It is the front view and side view of a jig | tool for demonstrating the shape of the jig | tool used for evaluation of the dent recovery rate of the thermoplastic resin foam of this invention. 動的防塵性を評価する際に使用される評価用サンプルの形状を示す平面図である。It is a top view which shows the shape of the sample for evaluation used when evaluating dynamic dustproofness. 評価用サンプルを組み付けた動的防塵性評価用の評価容器の上面図及びＡ－Ａ’線概略断面図である。FIG. 4 is a top view and a schematic cross-sectional view taken along line A-A ′ of an evaluation container for dynamic dustproof evaluation assembled with an evaluation sample. 評価容器を置いたタンブラーを示す概略図である。It is the schematic which shows the tumbler which set | placed the evaluation container.
　本発明の熱可塑性樹脂発泡体（以下、単に「樹脂発泡体」ということがある）は、熱可塑性樹脂を含む発泡体であり、熱可塑性樹脂組成物を、発泡・成形することにより得られる。本発明の樹脂発泡体の形状は、特に限定されず、例えば、塊状、シート状、フィルム状等のいずれの形態であってもよい。 The thermoplastic resin foam of the present invention (hereinafter sometimes simply referred to as “resin foam”) is a foam containing a thermoplastic resin, and is obtained by foaming and molding a thermoplastic resin composition. The shape of the resin foam of this invention is not specifically limited, For example, any forms, such as a lump shape, a sheet form, and a film form, may be sufficient.
　〔樹脂発泡体の物性〕
　本発明の樹脂発泡体は、下記で定義される２３℃での凹み回復率が５０％以上であり、好ましくは５２％以上、５５％以上、より好ましくは６０％以上、特に好ましくは６５％以上である。
　凹み回復率は、熱可塑性樹脂発泡体を、刃角９０度の治具によって、樹脂発泡体の厚み方向の最下点まで圧縮して１５秒間維持した後、圧縮状態を解除し、圧縮状態解除６０秒後の凹み部分の厚みの初期厚みに対する割合として定義される。 [Physical properties of resin foam]
The resin foam of the present invention has a dent recovery rate at 23 ° C. defined below of 50% or more, preferably 52% or more, 55% or more, more preferably 60% or more, and particularly preferably 65% or more. It is.
The dent recovery rate is determined by compressing the thermoplastic resin foam to the lowest point in the thickness direction of the resin foam with a jig having a blade angle of 90 degrees and maintaining it for 15 seconds, then releasing the compressed state and releasing the compressed state. It is defined as the ratio of the thickness of the recessed portion after 60 seconds to the initial thickness.
　この凹み回復率の評価に用いる刃角９０度の治具は、例えば、図１に示すように、樹脂発泡体に凹みを与える刃の先端が直角であり、その一辺の長さＬが１～２０ｍｍ程度、好ましくは５ｍｍ程度であり、その厚みＭが１～２０ｃｍ程度、好ましくは５ｃｍ程度のものが挙げられる。樹脂発泡体に凹みを与える刃の先端が、刃を側面から見た場合に直角である限り、一辺の長さＬ及び厚みＭの変動は、凹み回復率にほとんど影響を与えない。 For example, as shown in FIG. 1, a jig having a blade angle of 90 degrees used for evaluating the dent recovery rate has a right edge at the tip of the blade that gives a dent to the resin foam, and the length L of one side thereof is 1 to 1. The thickness is about 20 mm, preferably about 5 mm, and the thickness M is about 1 to 20 cm, preferably about 5 cm. As long as the tip of the blade that gives a dent to the resin foam is a right angle when the blade is viewed from the side, variations in the length L and the thickness M on one side have little effect on the dent recovery rate.
　本発明の樹脂発泡体は、２３℃で５０％以上の凹み回復率を有するため、歪の回復性に優れる。よって、本発明の樹脂発泡体は、良好な防塵性、特に良好な動的防塵性（動的環境下での防塵性能）を発揮することができる。その結果、本発明の樹脂発泡体を、発泡シール材として、携帯電話及び携帯型情報端末機等のクリアランスに組み付けた際、振動、落下時の衝撃によって樹脂発泡体が圧縮され、組み付けられたクリアランスを完全に塞がない状態に変形しても、速やかにかつ十分に凹みが回復し、クリアランスを十分に塞ぐことができ、塵等の異物の進入を効果的に防止することができる。 Since the resin foam of the present invention has a dent recovery rate of 50% or more at 23 ° C., it is excellent in strain recovery. Therefore, the resin foam of the present invention can exhibit good dust resistance, in particular, good dynamic dust resistance (dustproof performance in a dynamic environment). As a result, when the resin foam of the present invention is assembled as a foam sealing material in the clearance of a mobile phone, a portable information terminal, etc., the resin foam is compressed by vibration and impact at the time of dropping, and the assembled clearance Even if it is deformed to a state where it is not completely closed, the dent can be recovered quickly and sufficiently, the clearance can be sufficiently closed, and the entry of foreign matter such as dust can be effectively prevented.
　特に、面単位での厚み回復率（後述する歪回復率）が良好であったとしても、凹み回復率が良好でなければ、部分的な凹みの回復が十分に得られず、クリアランスの閉塞を完全に行うことができないため、十分な防塵効果が得られないことがある。本発明のように、部分的な応力による凹み、つまり、面単位での圧縮に比較してより過酷な条件下での短時間での回復率が良好であることにより、より一層の動的防塵性を確保することが可能となる。 In particular, even if the thickness recovery rate per unit surface (strain recovery rate described later) is good, if the dent recovery rate is not good, partial dent recovery cannot be obtained sufficiently and the clearance is blocked. Since it cannot be performed completely, a sufficient dustproof effect may not be obtained. As in the present invention, dents due to partial stress, that is, a better recovery rate in a short time under more severe conditions compared to compression in units of planes, further dynamic dustproofing It becomes possible to ensure the sex.
　本発明の樹脂発泡体は、例えば、気泡構造が、独立気泡構造又は半連続半独立気泡構造（独立気泡構造と連続気泡構造とが混在している気泡構造であり、その割合は特に限定されない）であることが好ましい。特に、樹脂発泡体の独立気泡率が５０％以下、好ましくは４０％以下、より好ましくは３５％以下となっている気泡構造が挙げられる。この範囲により、衝撃が作用した際の圧縮変形時、樹脂から空気が抜けやすく、十分な衝撃吸収性を発揮させることができる。また、樹脂発泡体の独立気泡率が１０％以上、好ましくは１５％以上、より好ましくは２０％以上となっている気泡構造が挙げられる。この範囲により、連続気泡の割合を調整して、塵等の微小な粒子の通過を阻止し、防塵性を向上させることができる。
　なお、独立気泡率は、例えば、実施例に記載の方法によって測定することができる。 In the resin foam of the present invention, for example, the cell structure is a closed cell structure or a semi-continuous semi-closed cell structure (a cell structure in which a closed cell structure and an open cell structure are mixed, and the ratio is not particularly limited). It is preferable that In particular, a cell structure in which the closed cell ratio of the resin foam is 50% or less, preferably 40% or less, more preferably 35% or less can be mentioned. By this range, at the time of compressive deformation when an impact is applied, air can easily escape from the resin, and sufficient shock absorption can be exhibited. Further, there is a cell structure in which the closed cell ratio of the resin foam is 10% or more, preferably 15% or more, more preferably 20% or more. With this range, the ratio of open cells can be adjusted to prevent the passage of fine particles such as dust, thereby improving the dust resistance.
The closed cell ratio can be measured, for example, by the method described in the examples.
　本発明の樹脂発泡体は、さらに、気泡構造中の平均セル径が、１０～２００μｍ、好ましくは１０～１８０μｍ、より好ましくは１０～１５０μｍ、さらに好ましくは１０～９０μｍ、特に好ましくは２０～８０μｍである。
　この平均セル径は、例えば、デジタルマイクロスコープ（商品名「ＶＨ－８０００」キーエンス株式会社製）により、気泡部の拡大画像を取り込み、画像解析ソフト（商品名「Ｗｉｎ　ＲＯＯＦ」三谷商事株式会社製）を用いて画像解析することにより求めることができる。 The resin foam of the present invention further has an average cell diameter in the cell structure of 10 to 200 μm, preferably 10 to 180 μm, more preferably 10 to 150 μm, still more preferably 10 to 90 μm, and particularly preferably 20 to 80 μm. is there.
This average cell diameter is obtained by, for example, capturing an enlarged image of the bubble portion with a digital microscope (trade name “VH-8000”, manufactured by Keyence Corporation), and image analysis software (trade name “Win ROOF”, manufactured by Mitani Corporation). It can obtain | require by carrying out image analysis using.
　本願発明の樹脂発泡体において、発泡体の平均セル径の上限を２００μｍ以下、好ましくは１８０μｍ以下又は１５０μｍ以下、さらに好ましくは９０μｍ以下、特に好ましくは８０μｍ以下とすることにより、防塵性を高めるとともに、遮光性を良好とすることができる。その一方、発泡体の平均セル径の下限を１０μｍ以上、好ましくは２０μｍ以上とすることにより、クッション性（衝撃吸収性）を良好とすることができる。 In the resin foam of the present invention, the upper limit of the average cell diameter of the foam is 200 μm or less, preferably 180 μm or less or 150 μm or less, more preferably 90 μm or less, and particularly preferably 80 μm or less, thereby improving dust resistance, The light shielding property can be improved. On the other hand, when the lower limit of the average cell diameter of the foam is 10 μm or more, preferably 20 μm or more, cushioning properties (impact absorption) can be improved.
　本発明の樹脂発泡体は、さらに、見掛け密度が、好ましくは０．０１～０．２０ｇ／ｃｍ3、より好ましくは０．０１～０．１５ｇ／ｃｍ3、０．０１～０．１０ｇ／ｃｍ3、さらに好ましくは０．０２～０．０８ｇ／ｃｍ3である。見掛け密度をこの範囲とする場合には、強度を十分に確保することができ、良好な加工性（特に打ち抜き加工性）を得ることができる。同時に、柔軟性をも確保することができ、発泡シール材として用いた際に微小なクリアランスに対する追従性を得ることができる。 The resin foam of the present invention further has an apparent density of preferably 0.01 to 0.20 g / cm 3 , more preferably 0.01 to 0.15 g / cm 3 , and 0.01 to 0.10 g / cm 3 . 3 , more preferably 0.02 to 0.08 g / cm 3 . When the apparent density is within this range, the strength can be sufficiently secured and good workability (particularly punching workability) can be obtained. At the same time, flexibility can be ensured, and followability to minute clearances can be obtained when used as a foamed sealing material.
　本発明の樹脂発泡体は、さらに、下記で定義される２３℃での５０％圧縮時の反発応力が、好ましくは０．１～３．０Ｎ／ｃｍ2、好ましくは０．１～２．０Ｎ／ｃｍ2、より好ましくは０．１～１．７Ｎ／ｃｍ2である。２３℃での５０％圧縮時の反発応力は、樹脂発泡体を、上述したように、２３℃で、初期厚みに対して５０％の厚みに圧縮した際の対反発荷重として定義される。 The resin foam of the present invention further has a repulsion stress at 50% compression at 23 ° C., defined below, of preferably 0.1 to 3.0 N / cm 2 , preferably 0.1 to 2.0 N. / Cm 2 , more preferably 0.1 to 1.7 N / cm 2 . The repulsive stress at the time of 50% compression at 23 ° C. is defined as the repulsive load when the resin foam is compressed to a thickness of 50% with respect to the initial thickness at 23 ° C. as described above.
　本願発明の樹脂発泡体がこの範囲の５０％圧縮時の反発応力を有する場合には、良好な柔軟性を発揮させることができる。よって、特に、この樹脂発泡体を発泡シール材として用いた場合、微小クリアランスに対する追従性を発揮することができる。このため、本発明の樹脂発泡体を発泡シール材としてクリアランスに組み付けた場合、たとえクリアランスが狭くても、発泡シール材の反発による不具合（例えば、発泡シール材の周りの部材又は筐体等を変形させること、画像表示部に色ムラを生じさせること等）の発生を防止することができる。 When the resin foam of the present invention has a rebound stress at the time of 50% compression in this range, good flexibility can be exhibited. Therefore, in particular, when this resin foam is used as a foam sealing material, it is possible to exhibit followability with respect to a minute clearance. For this reason, when the resin foam of the present invention is assembled into a clearance as a foam seal material, even if the clearance is narrow, a problem due to the repulsion of the foam seal material (for example, deformation of a member or casing around the foam seal material) Occurrence of color unevenness in the image display unit, etc.) can be prevented.
　本発明の樹脂発泡体は、上述したように、特定の凹み回復率を備えるとともに、特定の平均セル径、特定の見掛け密度及び／又は特定の２３℃での５０％圧縮時の反発応力を有することにより、微小なクリアランスにより追従させることができ、防塵性及び柔軟性をより一層向上させることができ、特に動的防塵性を著しく向上させることが可能となる。 As described above, the resin foam of the present invention has a specific dent recovery rate and a specific average cell diameter, a specific apparent density, and / or a specific repulsion stress at 50% compression at 23 ° C. As a result, it can be followed by a minute clearance, dust resistance and flexibility can be further improved, and dynamic dust resistance can be significantly improved.
　本発明の樹脂発泡体は、さらに、下記で定義される２３℃での厚み回復率が、５０％以上（例えば、５０～１００％）であり、好ましくは６５％以上（例えば６５～１００％）であり、より好ましくは７０％以上（例えば７０～１００％）であり、さらに好ましくは７５％以上（例えば７５～１００％）である。 The resin foam of the present invention further has a thickness recovery rate at 23 ° C. defined below of 50% or more (for example, 50 to 100%), preferably 65% or more (for example, 65 to 100%). More preferably, it is 70% or more (for example, 70 to 100%), and more preferably 75% or more (for example, 75 to 100%).
　２３℃での厚み回復率は、樹脂発泡体を、上述したように、２３℃で、初期厚みに対して２０％の厚みに１分間圧縮した後、圧縮状態を解除した場合において、圧縮状態解除１秒後の厚みの初期の厚みに対する割合として定義される。 As described above, the thickness recovery rate at 23 ° C. is that when the compressed state is released after the resin foam is compressed at 23 ° C. to a thickness of 20% of the initial thickness for 1 minute. It is defined as the ratio of the thickness after 1 second to the initial thickness.
　本発明の樹脂発泡体は、５０％以上の厚み回復率を有するため、歪の回復性が迅速であり、これにより良好な防塵性、特に良好な動的防塵性（動的環境下での防塵性能）を発揮することができる。この樹脂発泡体が、例えば、発泡シール材として、クリアランスに組み付けられている場合において、振動及び落下時の衝撃によって発泡シール材が変形した際、つまり発泡シール材が圧縮され、組み付けられたクリアランス以下の厚みになる状態に変形した際、極めて速やかに厚みが回復し、クリアランスを埋めることができる。これにより、塵等の異物の進入を防ぐことができる。 Since the resin foam of the present invention has a thickness recovery rate of 50% or more, the strain recovery property is quick, and thereby good dust resistance, particularly good dynamic dust resistance (dust protection under dynamic environment). Performance). In the case where this resin foam is assembled in a clearance, for example, as a foam seal material, when the foam seal material is deformed by vibration and impact at the time of dropping, that is, the foam seal material is compressed and below the assembled clearance. When the film is deformed to a thickness of 5 mm, the thickness is recovered very quickly and the clearance can be filled. Thereby, the entrance of foreign matter such as dust can be prevented.
　本発明の樹脂発泡体は、さらに、－１０℃での５０％圧縮時の反発応力が、好ましくは１０．０Ｎ／ｃｍ2未満、より好ましくは、９Ｎ／ｃｍ2以下、８Ｎ／ｃｍ2以下さらに好ましくは７Ｎ／ｃｍ2以下又は５Ｎ／ｃｍ2以下である。
　ここでの５０％圧縮時の反発応力は、上述したように、２３℃で、５０％圧縮時の反発応力と、温度が異なる以外、同様の対反発荷重として定義される。
　このように、低温における５０％圧縮時の反発応力をこの範囲とすることにより、より柔軟性を確保することが可能となる。 Resin foam of the present invention further, repulsion stress at 50% compression at -10 ° C. is preferably less than 10.0 N / cm 2, more preferably, 9N / cm 2 or less, 8N / cm 2 or less further preferably is 7N / cm 2 or less or 5N / cm 2 or less.
The repulsive stress at 50% compression here is defined as the same repulsive load except that the repulsive stress at 50% compression is different from that at 50 ° C. as described above.
Thus, by making the repulsive stress at the time of 50% compression at a low temperature within this range, it becomes possible to ensure more flexibility.
　本発明の樹脂発泡体は、さらに、２３℃での８０％圧縮時の反発応力が、好ましくは１．０～９．０Ｎ／ｃｍ2、より好ましくは１．０～８Ｎ／ｃｍ2、さらに好ましくは１．０～７．５Ｎ／ｃｍ2である。
　ここでの８０％圧縮時の反発応力とは、樹脂発泡体を、上述したように、２３℃において、初期厚みに対して８０％の厚みに圧縮した際の対反発荷重として定義される。 The resin foam of the present invention further has a repulsion stress at 80% compression at 23 ° C. of preferably 1.0 to 9.0 N / cm 2 , more preferably 1.0 to 8 N / cm 2 , and even more preferably. Is 1.0 to 7.5 N / cm 2 .
The repulsive stress at the time of 80% compression here is defined as the repulsive load when the resin foam is compressed to 80% of the initial thickness at 23 ° C. as described above.
　本発明の樹脂発泡体は、さらに、２３℃での歪回復率が７５％以上であることが好ましく、より好ましくは８０％以上、さらに好ましくは８５％以上である。
　ここで、歪回復率とは、厚み方向に、初期厚みに対して５０％の厚みに２４時間圧縮した後、圧縮状態を解除した場合において、圧縮状態解除２４時間後の厚みの初期厚みに対する割合として定義される。 The resin foam of the present invention further preferably has a strain recovery rate at 23 ° C. of 75% or more, more preferably 80% or more, and still more preferably 85% or more.
Here, the strain recovery rate is the ratio of the thickness 24 hours after the release of the compressed state to the initial thickness when the compressed state is released after being compressed to 50% of the initial thickness in the thickness direction for 24 hours. Is defined as
　本発明の樹脂発泡体は、７５％以上の歪回復率を有するため、長時間にわたった負荷が持続されても、その後の歪の回復性に優れ、良好な防塵性、特に良好な動的防塵性（動的環境下での防塵性能）を発揮することができる。 Since the resin foam of the present invention has a strain recovery rate of 75% or more, even if a load is maintained for a long time, it is excellent in recovering the subsequent strain, good dust resistance, particularly good dynamic Dustproofness (dustproofness in a dynamic environment) can be demonstrated.
　このように、本発明の樹脂発泡体は、２３℃での凹み回復率、－１０℃での５０％圧縮時の反発応力、２３℃での厚み回復率、２３℃での８０％圧縮時の反発応力、２３℃での歪回復率の２つ以上、好ましくは全てを良好なものとする場合には、通常考えられる樹脂発泡体の変形に対して、どのような温度範囲においても、十分かつ速やかに、その形状を回復することができ、特に本発明で意図する動的環境下での防塵性能を最大限に発揮させることができる。また、携帯電話等の画像表示部での使用に際しては、十分な遮光性又は光漏れを防止することができる。 Thus, the resin foam of the present invention has a dent recovery rate at 23 ° C., rebound stress at 50% compression at −10 ° C., thickness recovery rate at 23 ° C., and 80% compression at 23 ° C. When two or more, preferably all, of the rebound stress and the strain recovery rate at 23 ° C. are satisfactory, it is sufficient in any temperature range with respect to the deformation of the resin foam that is normally considered. The shape can be quickly recovered, and the dustproof performance under the dynamic environment intended in the present invention can be maximized. In addition, when used in an image display unit such as a mobile phone, sufficient light shielding properties or light leakage can be prevented.
　〔樹脂発泡体の材料〕
　本発明の樹脂発泡体は、熱可塑性樹脂又は熱可塑性樹脂を含有する樹脂組成物によって形成される。
　熱可塑性樹脂としては、例えば、低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレン、線状低密度ポリエチレン、ポリプロピレン、エチレンとプロピレンとの共重合体、エチレン又はプロピレンと他のα－オレフィン（例えば、ブテン－１、ペンテン－１、ヘキセン－１、４－メチルペンテン－１など）との共重合体、エチレンと他のエチレン性不飽和単量体（例えば、酢酸ビニル、アクリル酸、アクリル酸エステル、メタクリル酸、メタクリル酸エステル、ビニルアルコールなど）との共重合体などのポリオレフィン系樹脂；ポリスチレン、アクリロニトリル－ブタジエン－スチレン共重合体（ＡＢＳ樹脂）などのスチレン系樹脂；６－ナイロン、６６－ナイロン、１２－ナイロンなどのポリアミド系樹脂；ポリアミドイミド；ポリウレタン；ポリイミド；ポリエーテルイミド；ポリメチルメタクリレートなどのアクリル系樹脂；ポリ塩化ビニル；ポリフッ化ビニル；アルケニル芳香族樹脂；ポリエチレンテレフタレート、ポリブチレンテレフタレートなどのポリエステル系樹脂；ビスフェノールＡ系ポリカーボネートなどのポリカーボネート；ポリアセタール；ポリフェニレンスルフィドなどが挙げられる。
　熱可塑性樹脂は、単独で又は２種以上を組み合わせて用いることができる。熱可塑性樹脂が共重合体である場合、ランダム共重合体、ブロック共重合体のいずれの形態の共重合体であってもよい。 [Material of resin foam]
The resin foam of the present invention is formed by a thermoplastic resin or a resin composition containing a thermoplastic resin.
Examples of the thermoplastic resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, a copolymer of ethylene and propylene, ethylene or propylene and another α-olefin (for example, butene -1, pentene-1, hexene-1, 4-methylpentene-1, etc.), ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylic ester, methacrylic) Polyolefin resins such as copolymers with acid, methacrylic acid ester, vinyl alcohol, etc.); styrene resins such as polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin); 6-nylon, 66-nylon, 12 -Polyamide resins such as nylon; polyamideimide Polyurethane; Polyimide; Polyetherimide; Acrylic resin such as polymethyl methacrylate; Polyvinyl chloride; Polyvinyl fluoride; Alkenyl aromatic resin; Polyester resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate such as bisphenol A polycarbonate; Polyacetal; polyphenylene sulfide and the like.
A thermoplastic resin can be used individually or in combination of 2 or more types. When the thermoplastic resin is a copolymer, the copolymer may be a random copolymer or a block copolymer.
　熱可塑性樹脂としては、機械強度、耐熱性、耐薬品性等の特性面、溶融熱成形が容易等の成形面から、ポリオレフィン系樹脂が好適である。
　ポリオレフィン系樹脂としては、分子量分布が広くかつ高分子量側にショルダーをもつタイプの樹脂、微架橋タイプの樹脂（若干架橋されたタイプの樹脂）、長鎖分岐タイプの樹脂などが好適に挙げられる。 As the thermoplastic resin, a polyolefin-based resin is preferable from the viewpoints of characteristics such as mechanical strength, heat resistance, and chemical resistance, and molding surfaces such as easy melt thermoforming.
Preferred examples of the polyolefin resin include a resin having a broad molecular weight distribution and having a shoulder on the high molecular weight side, a micro-crosslinking type resin (a slightly cross-linked type resin), a long-chain branched type resin, and the like.
　特に、ポリオレフィン系樹脂としては、発泡倍率が高く、かつ均一な気泡構造を有する樹脂発泡体を得る点から、溶融張力（温度：２１０℃、引張速度：２．０ｍ／ｍｉｎ、キャピラリー：φ１ｍｍ×１０ｍｍ）が３～５０ｃＮ（好ましくは８～５０ｃＮ）であるポリオレフィン系樹脂が好ましい。 In particular, as a polyolefin-based resin, melt tension (temperature: 210 ° C., tensile speed: 2.0 m / min, capillary: φ1 mm × 10 mm from the viewpoint of obtaining a resin foam having a high foaming ratio and a uniform cell structure. ) Is preferably 3 to 50 cN (preferably 8 to 50 cN).
　熱可塑性樹脂には、ゴム成分及び／又は熱可塑性エラストマー成分が含まれる。
　ゴム成分及び熱可塑性エラストマー成分は、例えば、ガラス転移温度が室温以下（例えば２０℃以下）であるため、樹脂発泡体としたときの柔軟性及び形状追随性が極めて良好となる。 The thermoplastic resin includes a rubber component and / or a thermoplastic elastomer component.
Since the rubber component and the thermoplastic elastomer component have, for example, a glass transition temperature of room temperature or lower (for example, 20 ° C. or lower), flexibility and shape followability when a resin foam is obtained are extremely good.
　ゴム成分及び熱可塑性エラストマー成分としては、ゴム弾性を有し、発泡可能なものであれば特に限定はなく、例えば、天然ゴム、ポリイソブチレン、ポリイソプレン、クロロプレンゴム、ブチルゴム、ニトリルブチルゴムなどの天然又は合成ゴム；エチレン－プロピレン共重合体、エチレン－プロピレン－ジエン共重合体、エチレン－酢酸ビニル共重合体、ポリブテン、塩素化ポリエチレンなどのオレフィン系エラストマー；スチレン－ブタジエン－スチレン共重合体、スチレン－イソプレン－スチレン共重合体及びそれらの水素添加物などのスチレン系エラストマー；ポリエステル系エラストマー；ポリアミド系エラストマー；ポリウレタン系エラストマーなどの各種熱可塑性エラストマーなどが挙げられる。
　これらは単独で又は２種以上を組み合わせて用いてもよい。 The rubber component and the thermoplastic elastomer component are not particularly limited as long as they have rubber elasticity and can be foamed. For example, natural or natural rubber, polyisobutylene, polyisoprene, chloroprene rubber, butyl rubber, nitrile butyl rubber, or the like Synthetic rubbers; Ethylene-propylene copolymers, ethylene-propylene-diene copolymers, ethylene-vinyl acetate copolymers, polybutenes, olefinic elastomers such as chlorinated polyethylene; styrene-butadiene-styrene copolymers, styrene-isoprene -Styrene elastomers such as styrene copolymers and hydrogenated products thereof; polyester elastomers; polyamide elastomers; various thermoplastic elastomers such as polyurethane elastomers.
You may use these individually or in combination of 2 or more types.
　なかでも、ゴム成分及び／又は熱可塑性エラストマー成分としては、オレフィン系エラストマーが好ましい。オレフィン系エラストマーは、熱可塑性樹脂として例示されているポリオレフィン系樹脂との相溶性が良好である。 Among these, as the rubber component and / or the thermoplastic elastomer component, an olefin elastomer is preferable. The olefin elastomer has good compatibility with the polyolefin resin exemplified as the thermoplastic resin.
　オレフィン系エラストマーは、樹脂成分Ａ（オレフィン系樹脂成分Ａ）とゴム成分Ｂとがミクロ相分離した構造を有するタイプであってもよいし、樹脂成分Ａとゴム成分Ｂとを物理的に分散させたタイプであってもよいし、樹脂成分Ａとゴム成分Ｂとを、架橋剤の存在下、動的に熱処理したタイプ（動的架橋型熱可塑性エラストマー、ＴＰＶ）であってもよい。なかでも、オレフィン系エラストマーとしては、動的架橋型熱可塑性オレフィン系エラストマー（ＴＰＶ）が好ましい。 The olefin-based elastomer may be a type having a structure in which the resin component A (olefin-based resin component A) and the rubber component B are microphase-separated, or the resin component A and the rubber component B are physically dispersed. The resin component A and the rubber component B may be dynamically heat treated in the presence of a cross-linking agent (dynamic cross-linkable thermoplastic elastomer, TPV). Among these, as the olefin elastomer, a dynamically crosslinked thermoplastic olefin elastomer (TPV) is preferable.
　動的架橋型熱可塑性オレフィン系エラストマーはＴＰＯ（非架橋型の熱可塑性オレフィン系エラストマー）より、弾性率が高く、かつ圧縮永久歪みも小さい。これにより、回復性が良好であり、樹脂発泡体とした場合に優れた回復性を示す。 Dynamically-crosslinked thermoplastic olefin elastomer has higher elastic modulus and smaller compression set than TPO (non-crosslinked thermoplastic olefin elastomer). Thereby, the recoverability is good, and when the resin foam is used, the excellent recoverability is exhibited.
　動的架橋型熱可塑性オレフィン系エラストマーとは、上述したように、マトリックスを形成する樹脂成分Ａ（オレフィン系樹脂成分Ａ）及びドメインを形成するゴム成分Ｂを含む混合物を、架橋剤の存在下、動的に熱処理することにより得られ、マトリックス（海相）である樹脂成分Ａ中に、架橋ゴム粒子がドメイン（島相）として細かく分散した海島構造を有する多相系のポリマーである。 As described above, the dynamically crosslinked thermoplastic olefin elastomer is a mixture containing the resin component A (olefin resin component A) forming a matrix and the rubber component B forming a domain, in the presence of a crosslinking agent. It is a multiphase polymer having a sea-island structure in which crosslinked rubber particles are finely dispersed as domains (island phases) in the resin component A, which is a matrix (sea phase), obtained by dynamic heat treatment.
　このような動的架橋型熱可塑性オレフィン系エラストマーとしては、例えば、特開２０００－００７８５８号公報、特開２００６－０５２２７７号公報、特開２０１２－０７２３０６号公報、特開２０１２－０５７０６８号公報、特開２０１０－２４１８９７号公報、特開２００９－０６７９６９号公報、再表０３／００２６５４号等に記載のもの、「ゼオサーム」（日本ゼオン社製）、「サーモラン」（三菱化学社製）、「サーリンク３２４５Ｄ」（東洋紡績株式会社製）等として市販されているもの等が挙げられる。 Examples of such a dynamically crosslinked thermoplastic olefin elastomer include, for example, JP 2000-007858 A, JP 2006-052277 A, JP 2012-072306 A, JP 2012-056768 A, JP-A-2010-241897, JP-A-2009-0697969, RE-list 03/002654, etc., “Zeotherm” (manufactured by Zeon Corporation), “Thermorun” (manufactured by Mitsubishi Chemical Corporation), “Surlink” 3245D "(manufactured by Toyobo Co., Ltd.) and the like.
　本発明の樹脂発泡体を構成する樹脂として、熱可塑性樹脂とともに、ゴム成分及び／又は熱可塑性エラストマー成分を含む場合、その含有率としては、特に限定されない。例えば、本発明の樹脂発泡体を構成する樹脂における、熱可塑性樹脂とゴム成分及び／又は熱可塑性エラストマー成分との割合は、重量基準で、好ましくは７０／３０～３０／７０が好ましく、より好ましくは６０／４０～３０／７０であり、さらにより好ましくは５０／５０～３０／７０であり、より一層好ましくは、６０／４０～１０／９０、５８／４２～１０／９０、５５／４５～１０／９０である。ゴム成分及び／又は熱可塑性エラストマー成分の割合が少なすぎると樹脂発泡体のクッション性が低下しやすくなり又は圧縮後の回復性が低下することがあり、一方、ゴム成分及び／又は熱可塑性エラストマー成分の割合が多すぎると発泡体形成時にガス抜けが生じやすくなり、高発泡性の発泡体を得ることが困難になることがある。 In the case where the resin constituting the resin foam of the present invention contains a rubber component and / or a thermoplastic elastomer component together with the thermoplastic resin, the content is not particularly limited. For example, the ratio of the thermoplastic resin to the rubber component and / or the thermoplastic elastomer component in the resin constituting the resin foam of the present invention is preferably 70/30 to 30/70, more preferably on a weight basis. Is 60/40 to 30/70, even more preferably 50/50 to 30/70, even more preferably 60/40 to 10/90, 58/42 to 10/90, 55/45 to 10/90. If the ratio of the rubber component and / or the thermoplastic elastomer component is too small, the cushioning property of the resin foam tends to be lowered or the recoverability after compression may be lowered. On the other hand, the rubber component and / or the thermoplastic elastomer component If the ratio is too large, outgassing tends to occur during foam formation, and it may be difficult to obtain a highly foamable foam.
　本発明の樹脂発泡体では、高圧縮時の柔軟性及び圧縮後の形状回復を実現するために、つまり、大変形を可能とし、塑性変形を起こさないようにするために、いわゆるゴム弾性に優れた材料を用いることが適している。その観点から、本発明の樹脂発泡体では、構成する樹脂組成物として、上述した熱可塑性樹脂とともに、ゴム成分及び／又は熱可塑性エラストマー成分を含むことが好ましい。 The resin foam of the present invention is excellent in so-called rubber elasticity in order to realize flexibility at high compression and shape recovery after compression, that is, to enable large deformation and prevent plastic deformation. Suitable materials are suitable. From this viewpoint, the resin foam of the present invention preferably contains a rubber component and / or a thermoplastic elastomer component together with the above-described thermoplastic resin as the constituent resin composition.
　本発明の樹脂発泡体は、その構成樹脂組成物において、さらに、造核剤が含まれることが好ましい。造核剤が含まれていると、セル径を容易に調整することができ、適度な柔軟性を有するとともに、切断加工性に優れた発泡体を得ることができる。 The resin foam of the present invention preferably further contains a nucleating agent in the constituent resin composition. When the nucleating agent is contained, the cell diameter can be easily adjusted, and a foam having an appropriate flexibility and excellent cutting processability can be obtained.
　造核剤としては、例えば、タルク、シリカ、アルミナ、ゼオライト、炭酸カルシウム、炭酸マグネシウム、硫酸バリウム、酸化亜鉛、酸化チタン、水酸化アルミニウム、水酸化マグネシウム、マイカ、モンモリナイトなどの酸化物、複合酸化物、金属炭酸塩、金属硫酸塩、金属水酸化物；カーボン粒子、グラスファイバー、カーボンチューブなどが挙げられる。なお、造核剤は、単独で又は２種以上を組み合わせて用いられる。 Examples of the nucleating agent include oxides and composite oxides such as talc, silica, alumina, zeolite, calcium carbonate, magnesium carbonate, barium sulfate, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, mica, and montmorillonite. Metal carbonates, metal sulfates, metal hydroxides; carbon particles, glass fibers, carbon tubes, and the like. In addition, a nucleating agent is used individually or in combination of 2 or more types.
　造核剤の平均粒子径は、特に限定されないが、好ましくは０．３～１．５μｍであり、より好ましくは０．４～１．２μｍである。このような平均粒子径とすることにより、造核剤としての十分な機能を発揮させることができる。また、造核剤がセルの壁を突き破ることなく、高発泡倍率を実現できる。
　この平均粒子径は、レーザー回折式の粒度分布測定法により測定することができる。例えば、ＬＥＥＤＳ　＆　ＮＯＲＴＨＲＵＰ　ＩＮＳＴＲＵＭＥＮＴＳ　社製「ＭＩＣＲＯＴＲＡＣ　ＭＴ－３０００」により、試料の分散希釈液から測定（ＡＵＴＯ測定モード）することができる。 The average particle size of the nucleating agent is not particularly limited, but is preferably 0.3 to 1.5 μm, more preferably 0.4 to 1.2 μm. By setting it as such an average particle diameter, sufficient function as a nucleating agent can be exhibited. In addition, a high expansion ratio can be realized without the nucleating agent breaking through the cell walls.
This average particle diameter can be measured by a laser diffraction particle size distribution measuring method. For example, the measurement can be performed from the sample dispersion dilution (AUTO measurement mode) using “MICROTRAC MT-3000” manufactured by LEEDS & NORTHRUP INSTRUMENTS.
　本発明の樹脂発泡体において、造核剤を含む場合の含有量は、特に限定されないが、構成する樹脂１００重量部に対して、好ましくは０．５～１５０重量部、より好ましくは２～１４０重量部、さらにより好ましくは３～１３０重量部である。 In the resin foam of the present invention, the content when a nucleating agent is included is not particularly limited, but is preferably 0.5 to 150 parts by weight, more preferably 2 to 140 parts by weight with respect to 100 parts by weight of the constituent resin. Part by weight, still more preferably 3 to 130 parts by weight.
　本発明の樹脂発泡体は、熱可塑性樹脂により構成されているため燃えやすいことから、難燃剤を含有することが好ましい。
　難燃剤としては、ノンハロゲン－ノンアンチモン系である無機難燃剤が好ましい。
　このような無機難燃剤としては、例えば、金属水酸化物や金属化合物の水和物などが挙げられる。より具体的には、水酸化アルミニウム；水酸化マグネシウム；酸化マグネシウムや酸化ニッケルの水和物；酸化マグネシウムや酸化亜鉛の水和物などが挙げられる。なかでも、水酸化マグネシウムが好適に挙げられる。上記水和金属化合物は表面処理されていてもよい。難燃剤は、単独で又は２種以上を組み合わせて用いられる。 Since the resin foam of this invention is comprised with a thermoplastic resin and is easy to burn, it is preferable to contain a flame retardant.
As the flame retardant, a non-halogen-nonantimony inorganic flame retardant is preferable.
Examples of such inorganic flame retardants include metal hydroxides and hydrates of metal compounds. More specifically, aluminum hydroxide; magnesium hydroxide; hydrates of magnesium oxide and nickel oxide; hydrates of magnesium oxide and zinc oxide, and the like. Among these, magnesium hydroxide is preferable. The hydrated metal compound may be surface-treated. A flame retardant is used individually or in combination of 2 or more types.
　本発明の樹脂発泡体において難燃剤が含まれる場合の含有量は、構成する樹脂１００重量部に対して、好ましくは５～７０重量部、より好ましくは２５～６５重量部である。 In the resin foam of the present invention, when the flame retardant is contained, the content is preferably 5 to 70 parts by weight, more preferably 25 to 65 parts by weight with respect to 100 parts by weight of the constituent resin.
　本発明の樹脂発泡体は、さらに、極性官能基を有し、融点が５０～１５０℃であり、脂肪酸、脂肪酸アミド、脂肪酸金属石鹸から選ばれた少なくとも一つの脂肪族系化合物を含有していてもよい。なかでも、脂肪酸、脂肪酸アミドが好ましい。 The resin foam of the present invention further has a polar functional group, a melting point of 50 to 150 ° C., and contains at least one aliphatic compound selected from fatty acids, fatty acid amides, and fatty acid metal soaps. Also good. Of these, fatty acids and fatty acid amides are preferred.
　本発明の樹脂発泡体において、このような脂肪族系化合物が含まれていると、加工（特に打ち抜き加工）の際に、気泡構造がつぶれにくくなり、形状回復性が向上し、加工性（特に打ち抜き加工性）がより向上する。このような脂肪族系化合物は結晶性が高く、上記熱可塑性樹脂（特にポリオレフィン系樹脂）に添加すると樹脂表面に強固な膜を形成し、気泡構造を形成する気泡の壁面同士が互いにブロッキングすることを防ぐ働きを有するためと推測される。 When such an aliphatic compound is contained in the resin foam of the present invention, the cell structure is less likely to collapse during processing (particularly punching processing), shape recovery is improved, and workability (particularly, (Punching workability) is further improved. Such an aliphatic compound has high crystallinity, and when added to the thermoplastic resin (especially polyolefin resin), a strong film is formed on the resin surface, and the wall surfaces of the bubbles forming the cell structure block each other. This is presumed to have a function to prevent the above.
　このような脂肪族系化合物は、特に、ポリオレフィン系樹脂に対しては、極性の高い官能基を含むものが、相溶しにくいため、樹脂発泡体表面に析出しやすく、上記の効果を発揮しやすい。 Such aliphatic compounds, particularly those containing a highly polar functional group, are difficult to be compatible with polyolefin resins, so that they easily precipitate on the surface of the resin foam and exhibit the above effects. Cheap.
　脂肪族系化合物の融点は、樹脂組成物を発泡成形する際の成形温度を下げ、樹脂（特にポリオレフィン系樹脂）の劣化を抑制する、耐昇華性を付与する等の観点から、好ましくは５０～１５０℃、より好ましくは７０～１００℃である。 The melting point of the aliphatic compound is preferably 50 to 50 from the viewpoints of lowering the molding temperature when foam-molding the resin composition, suppressing deterioration of the resin (particularly polyolefin resin), imparting sublimation resistance, and the like. 150 ° C., more preferably 70 to 100 ° C.
　脂肪酸としては、好ましくは炭素数１８～３８程度、より好ましくは炭素数１８～２２程度のものである。例えば、ステアリン酸、ベヘニン酸、１２－ヒドロキシステアリン酸などが挙げられる。なかでも、ベヘニン酸が特に好ましい。 The fatty acid preferably has about 18 to 38 carbon atoms, more preferably about 18 to 22 carbon atoms. For example, stearic acid, behenic acid, 12-hydroxystearic acid and the like can be mentioned. Of these, behenic acid is particularly preferable.
　脂肪酸アミドとしては、好ましくは、脂肪酸部分の炭素数が１８～３８程度、より好ましくは炭素数が１８～２２のものである。例えば、モノアミド、ビスアミドの何れであってもよい。具体的には、ステアリン酸アミド、オレイン酸アミド、エルカ酸アミド、メチレンビスステアリン酸アミド、エチレンビスステアリン酸アミドなどが挙げられる。なかでも、エルカ酸アミドが特に好ましい。 The fatty acid amide is preferably a fatty acid moiety having about 18 to 38 carbon atoms, more preferably 18 to 22 carbon atoms. For example, either monoamide or bisamide may be used. Specific examples include stearic acid amide, oleic acid amide, erucic acid amide, methylene bis stearic acid amide, and ethylene bis stearic acid amide. Of these, erucic acid amide is particularly preferable.
　脂肪酸金属石鹸としては、上記脂肪酸のアルミニウム、カルシウム、マグネシウム、リチウム、バリウム、亜鉛、鉛の塩などが挙げられる。 Examples of the fatty acid metal soap include aluminum, calcium, magnesium, lithium, barium, zinc and lead salts of the above fatty acids.
　本発明の樹脂発泡体において、このような脂肪族系化合物が含まれる場合の含有量は、特に限定されないが、構成する樹脂１００重量部に対して、好ましくは１～５重量部、より好ましくは１．５～３．５重量、さらにより好ましくは２～３重量部である。これにより、樹脂が発泡成形の際に十分な圧力を保つことができ、発泡剤（例えば、二酸化炭素、窒素などの不活性ガス）の含有量を確保して、高い発泡倍率が得ることができる。 In the resin foam of the present invention, the content when such an aliphatic compound is included is not particularly limited, but is preferably 1 to 5 parts by weight, more preferably 100 parts by weight of the resin constituting the resin foam. 1.5 to 3.5 parts by weight, still more preferably 2 to 3 parts by weight. As a result, the resin can maintain a sufficient pressure during foam molding, and the content of a foaming agent (for example, an inert gas such as carbon dioxide and nitrogen) can be ensured to obtain a high foaming ratio. .
　本発明の樹脂発泡体は、滑剤が含有されていてもよい。これにより、樹脂組成物の流動性を向上させるとともに、樹脂の熱劣化を抑制することができる。滑剤は、単独で又は２種以上を組み合わせて用いられる。 The resin foam of the present invention may contain a lubricant. Thereby, while improving the fluidity | liquidity of a resin composition, the thermal deterioration of resin can be suppressed. A lubricant is used individually or in combination of 2 or more types.
　滑剤としては、特に限定されないが、例えば、流動パラフィン、パラフィンワックス、マイクロワックス、ポリエチレンワックスなどの炭化水素系滑剤；ステアリン酸ブチル、ステアリン酸モノグリセリド、ペンタエリスリトールテトラステアレート、硬化ヒマシ油、ステアリン酸ステアリルなどのエステル系滑剤などが挙げられる。また、滑剤の含有量は、本発明の効果を損なわない範囲で適宜選択することができる。 The lubricant is not particularly limited. For example, hydrocarbon lubricants such as liquid paraffin, paraffin wax, microwax and polyethylene wax; butyl stearate, monoglyceride stearate, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate And ester lubricants. Moreover, content of a lubricant can be suitably selected in the range which does not impair the effect of this invention.
　本発明の樹脂発泡体は、必要に応じて、その他の添加剤が含有されていてもよい。このような添加剤としては、例えば、収縮防止剤、老化防止剤、熱安定剤、ＨＡＬＳ等の耐光剤、耐候剤、金属不活性剤、紫外線吸収剤、光安定剤、銅害防止剤等の安定剤、防菌剤、防かび剤、分散剤、粘着付与剤、カーボンブラックや有機顔料等の着色剤、充填剤などが挙げられる。特に、動的架橋型熱可塑性オレフィン系エラストマーを用いる場合、それを含有する組成物として添加剤（例えば、カーボンブラックなどの着色剤、軟化剤等）を含有したものを用いてもよい。これらの添加剤は、単独で又は２種以上を組み合わせて用いられる。
　これらの添加剤の含有量は、本発明の効果を損なわない範囲で適宜選択することができる。 The resin foam of the present invention may contain other additives as necessary. Examples of such additives include anti-shrinkage agents, anti-aging agents, heat stabilizers, light stabilizers such as HALS, weathering agents, metal deactivators, ultraviolet absorbers, light stabilizers, copper damage inhibitors, and the like. Stabilizers, antibacterial agents, fungicides, dispersants, tackifiers, colorants such as carbon black and organic pigments, fillers, and the like. In particular, when a dynamically crosslinked thermoplastic olefin elastomer is used, a composition containing an additive (for example, a colorant such as carbon black, a softening agent, etc.) may be used. These additives are used alone or in combination of two or more.
The content of these additives can be appropriately selected within a range that does not impair the effects of the present invention.
　〔樹脂発泡体の製造方法〕
　本発明の樹脂発泡体は、熱可塑性樹脂（ゴム成分及び／又は熱可塑性エラストマー成分を含む）、任意に、造核剤、脂肪族系化合物、滑剤等の添加剤を混合・混練するなどにより得られた樹脂組成物を用い、樹脂組成物を発泡・成形することにより製造することができる。 [Method for producing resin foam]
The resin foam of the present invention is obtained by mixing and kneading a thermoplastic resin (including a rubber component and / or a thermoplastic elastomer component) and optionally an additive such as a nucleating agent, an aliphatic compound, or a lubricant. It can manufacture by foaming and shape | molding a resin composition using the obtained resin composition.
　樹脂組成物を発泡・成形する際に用いられる発泡方法としては、特に限定されず、例えば、物理的方法、化学的方法等の通常用いられる方法が挙げられる。一般的な物理的方法は、クロロフルオロカーボン類又は炭化水素類などの低沸点液体（発泡剤）を樹脂に分散させ、次に加熱し発泡剤を揮発することにより気泡を形成させる方法である。また、一般的な化学的方法は、樹脂に添加した化合物（発泡剤）の熱分解により生じたガスにより気泡を形成させる方法である。 The foaming method used when foaming and molding the resin composition is not particularly limited, and examples thereof include usually used methods such as a physical method and a chemical method. A general physical method is a method of forming bubbles by dispersing a low boiling point liquid (foaming agent) such as chlorofluorocarbons or hydrocarbons in a resin, and then heating to volatilize the foaming agent. Moreover, a general chemical method is a method in which bubbles are formed by a gas generated by thermal decomposition of a compound (foaming agent) added to a resin.
　本発明では、発泡方法としては、セル径が小さくかつセル密度の高い発泡体を容易に得ることができる点から、発泡剤として高圧のガスを用いる方法が好ましい。特に発泡剤として高圧の不活性ガスを用いる方法が好ましい。
　発泡剤として高圧のガスを用いる方法としては、樹脂組成物に高圧のガスを含浸させた後、減圧する工程を経て形成する方法が好ましい。具体的には、樹脂組成物からなる未発泡成形物に高圧のガスを含浸させた後、減圧する工程を経て形成する方法、溶融した樹脂組成物にガスを加圧状態下で含浸させた後、減圧とともに成形に付して形成する方法などが挙げられる。 In the present invention, as a foaming method, a method using a high-pressure gas as a foaming agent is preferable because a foam having a small cell diameter and a high cell density can be easily obtained. In particular, a method using a high-pressure inert gas as a foaming agent is preferable.
As a method of using a high-pressure gas as a foaming agent, a method in which a resin composition is impregnated with a high-pressure gas and then subjected to a pressure reduction process is preferable. Specifically, after impregnating a high-pressure gas into an unfoamed molded product made of a resin composition, a method of forming through a step of reducing the pressure, after impregnating a molten resin composition with a gas under a pressurized state And a method of forming by forming together with decompression.
　不活性ガスとしては、樹脂発泡体の素材である樹脂に対して不活性でかつ含浸可能なものであれば特に限定されず、例えば、二酸化炭素、窒素、空気などが挙げられる。これらのガスは混合して用いてもよい。これらのうち、樹脂への含浸量が多く、含浸速度の速い点から、好ましくは二酸化炭素又は窒素、より好ましくは二酸化炭素である。 The inert gas is not particularly limited as long as it is inert and can be impregnated into the resin that is the material of the resin foam, and examples thereof include carbon dioxide, nitrogen, and air. These gases may be mixed and used. Of these, carbon dioxide or nitrogen is preferred, and carbon dioxide is more preferred because the amount of impregnation into the resin is large and the impregnation speed is fast.
　さらに、樹脂組成物への含浸速度を速めるという観点から、上記高圧のガス（特に不活性ガス、さらには二酸化炭素）は、超臨界状態のガスであることが好ましい。超臨界状態では、樹脂へのガスの溶解度が増大し、高濃度の混入が可能である。また、含浸後の急激な圧力降下時には、上記のように高濃度で含浸することが可能であるため、気泡核の発生が多くなり、その気泡核が成長してできる気泡の密度は気孔率が同じであっても大きくなるため、微細な気泡を得ることができる。例えば、二酸化炭素の臨界温度は３１℃、臨界圧力は７．４ＭＰａである。 Furthermore, from the viewpoint of increasing the impregnation rate into the resin composition, the high-pressure gas (particularly inert gas, and further carbon dioxide) is preferably a gas in a supercritical state. In the supercritical state, the solubility of the gas in the resin is increased and high concentration can be mixed. In addition, when the pressure drops suddenly after impregnation, since it is possible to impregnate at a high concentration as described above, the generation of bubble nuclei increases, and the density of bubbles formed by the growth of the bubble nuclei has a porosity. Even if they are the same, they become larger, so that fine bubbles can be obtained. For example, carbon dioxide has a critical temperature of 31 ° C. and a critical pressure of 7.4 MPa.
　発泡剤として高圧のガスを用いる方法により樹脂組成物を発泡・成形する方法としては、予め樹脂組成物を、シート状などの適宜な形状に成形して未発泡樹脂成形体（未発泡樹脂成形物）とした後、この未発泡樹脂成形体に、高圧のガスを含浸させ、圧力を解放することにより発泡させるバッチ方式、樹脂組成物を加圧下、高圧のガスと共に混練し、成形すると同時に圧力を解放し、成形と発泡を同時に行う連続方式のいずれでもよい。 As a method for foaming and molding a resin composition by a method using a high-pressure gas as a foaming agent, an unfoamed resin molded product (unfoamed resin molded product) is obtained by molding a resin composition into an appropriate shape such as a sheet shape in advance. After that, the unfoamed resin molded body is impregnated with a high-pressure gas and foamed by releasing the pressure, and the resin composition is kneaded with the high-pressure gas under pressure, and simultaneously molded and pressurized. Any of the continuous methods of releasing and simultaneously performing molding and foaming may be used.
　バッチ方式で樹脂組成物を発泡・成形する際に、発泡に供する未発泡樹脂成形体を形成する方法としては、例えば、樹脂組成物を、単軸押出機、二軸押出機等の押出機を用いて成形する方法；樹脂組成物を、ローラ、カム、ニーダ、バンバリ型等の羽根を設けた混練機を使用して均一に混練し、熱板のプレスなどを用いて所定の厚みにプレス成形する方法；樹脂組成物を、射出成形機を用いて成形する方法などが挙げられる。また、未発泡樹脂成形体は、押出成形、プレス成形、射出成形以外に、他の成形方法でも形成することもできる。さらに、未発泡樹脂成形体の形状は、特に限定されず、用途に応じて種々の形状を選択でき、例えば、シート状、ロール状、板状、塊状等が挙げられる。このように、バッチ方式で樹脂組成物を発泡又は成形する際には、所望の形状や厚さの未発泡樹脂成形体が得られる適宜な方法により樹脂組成物を成形することができる。 As a method of forming an unfoamed resin molded body to be used for foaming when foaming and molding a resin composition by a batch method, for example, the resin composition is an extruder such as a single screw extruder or a twin screw extruder. Molding method using a kneading machine equipped with blades such as rollers, cams, kneaders, Banbury molds, etc., and then kneading the resin composition to a predetermined thickness using a hot plate press or the like And a method of molding the resin composition using an injection molding machine. In addition, the unfoamed resin molded body can be formed by other molding methods besides extrusion molding, press molding, and injection molding. Furthermore, the shape of the unfoamed resin molded body is not particularly limited, and various shapes can be selected depending on the application, and examples thereof include a sheet shape, a roll shape, a plate shape, and a lump shape. Thus, when foaming or molding the resin composition in a batch mode, the resin composition can be molded by an appropriate method that can obtain an unfoamed resin molded body having a desired shape and thickness.
　バッチ方式で樹脂組成物を発泡又は成形する場合、得られた未発泡樹脂成形体を耐圧容器（高圧容器）中に入れて、高圧のガス（特に不活性ガス、さらには二酸化炭素）を注入（導入）し、未発泡樹脂成形体中に高圧のガスを含浸させるガス含浸工程、十分に高圧のガスを含浸させた時点で圧力を解放し（通常、大気圧まで）、樹脂中に気泡核を発生させる減圧工程、場合によっては（必要に応じて）、加熱することによって気泡核を成長させる加熱工程を経て、樹脂中に気泡を形成させる。加熱工程を設けずに、室温で気泡核を成長させてもよい。 When foaming or molding a resin composition by a batch method, the obtained unfoamed resin molded product is placed in a pressure vessel (high pressure vessel) and injected with high pressure gas (especially inert gas or even carbon dioxide) ( Gas) impregnating a non-foamed resin molded body with a high-pressure gas, releasing the pressure when the sufficiently high-pressure gas is impregnated (usually up to atmospheric pressure), and creating bubble nuclei in the resin Bubbles are formed in the resin through a decompression step to be generated, and in some cases (if necessary), a heating step in which bubble nuclei are grown by heating. Bubble nuclei may be grown at room temperature without providing a heating step.
　連続方式での樹脂組成物の発泡又は成形としては、樹脂組成物を、単軸押出機、二軸押出機等の押出機を使用して混練しながら、高圧のガス（特に不活性ガス、さらには二酸化炭素）を注入（導入）し、十分に高圧のガスを樹脂組成物に含浸させる混練含浸工程、押出機の先端に設けられたダイスなどを通して樹脂組成物を押し出すことにより圧力を解放し（通常、大気圧まで）、成形と発泡を同時に行う成形減圧工程により発泡又は成形することが挙げられる。これら混練含浸工程及び成形減圧工程では、押出機のほか、射出成形機などを用いてもよい。また、連続方式での樹脂組成物の発泡又は成形の際には、必要に応じて、加熱することによって気泡を成長させる加熱工程を設けてもよい。 As the foaming or molding of the resin composition in a continuous system, the resin composition is kneaded using an extruder such as a single screw extruder or a twin screw extruder while a high pressure gas (especially an inert gas, Is injected (introduced) carbon dioxide), and the pressure is released by extruding the resin composition through a kneading impregnation step for impregnating the resin composition with a sufficiently high pressure gas, a die provided at the tip of the extruder ( Usually, up to atmospheric pressure), foaming or molding may be performed by a molding decompression step in which molding and foaming are performed simultaneously. In the kneading impregnation step and the molding decompression step, an injection molding machine or the like may be used in addition to the extruder. In addition, when foaming or molding the resin composition in a continuous manner, a heating step for growing bubbles by heating may be provided as necessary.
　バッチ方式又は連続方式のいずれにおいても、気泡を成長させた後、必要により冷水などにより急激に冷却し、形状を固定化してもよい。高圧のガスの導入は連続的に行ってもよく不連続的に行ってもよい。気泡核を成長させる際の加熱の方法としては、ウォーターバス、オイルバス、熱ロール、熱風オーブン、遠赤外線、近赤外線、マイクロ波などの公知の方法を採用することができる。 In either the batch method or the continuous method, after the bubbles are grown, if necessary, the shape may be fixed rapidly by cooling with cold water or the like. The high-pressure gas may be introduced continuously or discontinuously. As a heating method for growing bubble nuclei, known methods such as a water bath, an oil bath, a hot roll, a hot air oven, a far infrared ray, a near infrared ray, and a microwave can be employed.
　本発明の樹脂発泡体を製造する場合、効率的に安定した発泡体を作製するために、上述した工程を経た後又は上述した工程中に延伸することが好ましい。 When producing the resin foam of the present invention, it is preferable to stretch after the above-described process or during the above-described process in order to produce an efficient and stable foam.
　延伸は、樹脂の押し出し速度と成形速度との比率が１：１．２～５となるように行うことが好ましい。
　延伸をこの範囲で行うことにより、樹脂シートの送りが、ロール又はベルトの摩擦抵抗で不安定になることを防止し、過剰な延伸で厚み方向に押しつぶされることを回避できる。その結果、空孔率、クッション性及び柔軟性を確保することができる。
　通常、樹脂がゴム成分及び／又は熱可塑性エラストマー成分を多く含有する場合には、ロール又はベルトに対する滑り性が低下するが、延伸を上記範囲で行うことにより、樹脂の組成にかかわらず、安定してシートを送ることができ、形状が安定した樹脂発泡体を得ることができる。
　ここで、成形速度とは、ロール又はベルトによって樹脂シートが送られる速度を意味する。成形速度は、特に限定されるものではなく、例えば、２～１００ｍ／分とすることが好ましい。これにより、安定的に樹脂シートを成形することができ、生産効率を確保することができる。
　また、ロール又はベルトによって樹脂シートをニップする場合、ニップ圧は、発泡体が厚み方向で潰れない程度とすることが好ましい。 The stretching is preferably performed so that the ratio of the resin extrusion speed and the molding speed is 1: 1.2 to 5.
By performing stretching in this range, it is possible to prevent the feeding of the resin sheet from becoming unstable due to the frictional resistance of the roll or the belt, and to avoid crushing in the thickness direction due to excessive stretching. As a result, porosity, cushioning properties and flexibility can be ensured.
Usually, when the resin contains a large amount of a rubber component and / or a thermoplastic elastomer component, the slipping property with respect to a roll or a belt is lowered. However, by performing stretching in the above range, the resin is stable regardless of the composition of the resin. Thus, a sheet can be sent and a resin foam having a stable shape can be obtained.
Here, the molding speed means a speed at which the resin sheet is fed by a roll or a belt. The molding speed is not particularly limited, and is preferably 2 to 100 m / min, for example. Thereby, a resin sheet can be shape | molded stably and production efficiency can be ensured.
When the resin sheet is nipped by a roll or a belt, the nip pressure is preferably set so that the foam is not crushed in the thickness direction.
　樹脂組成物の発泡又は成形する際のガスの混合量は、特に限定されないが、例えば、樹脂組成物中の樹脂成分全量に対して、好ましくは２～１０重量％、より好ましくは２．５～８重量％、さらにより好ましくは３～６重量％である。この範囲とすることにより、成形機内でガスが分離することなく、発泡率の高い発泡体を得ることができる。 The mixing amount of the gas at the time of foaming or molding the resin composition is not particularly limited. For example, it is preferably 2 to 10% by weight, more preferably 2.5 to 2.5%, based on the total amount of the resin components in the resin composition. 8% by weight, still more preferably 3-6% by weight. By setting it as this range, a foam with a high foaming rate can be obtained, without gas separating in a molding machine.
　本発明の樹脂発泡体において、樹脂組成物の発泡・成形する際のバッチ方式におけるガス含浸工程や連続方式における混練含浸工程で、ガスを未発泡樹脂成形体又は樹脂組成物に含浸させるときの圧力は、ガスの種類や操作性等を考慮して適宜選択できる。例えば、ガスとして不活性ガスを、特に二酸化炭素を用いる場合には、好ましくは６ＭＰａ以上（例えば、６～１００ＭＰａ）、より好ましくは８ＭＰａ以上（例えば、８～１００ＭＰａ）である。このような圧力に設定することにより、発泡時の気泡成長を適度に制御して、セル径を小さくすることができ、ひいては、良好な防塵効果を与えることができる。これは、ガスの含浸量が適当な量となり、気泡核形成速度を制御して、形成される気泡核数を適度な数に調整することができるためである。また、セル径及び気泡密度の制御が容易となる。 In the resin foam of the present invention, the pressure when impregnating the unfoamed resin molded product or the resin composition with the gas in the gas impregnation step in the batch method or the kneading impregnation step in the continuous method when foaming and molding the resin composition Can be appropriately selected in consideration of the type of gas and operability. For example, when an inert gas, particularly carbon dioxide, is used as the gas, the pressure is preferably 6 MPa or more (for example, 6 to 100 MPa), more preferably 8 MPa or more (for example, 8 to 100 MPa). By setting such a pressure, it is possible to moderately control the bubble growth during foaming, to reduce the cell diameter, and to provide a good dustproof effect. This is because the amount of gas impregnation becomes an appropriate amount, and the number of bubble nuclei formed can be adjusted to an appropriate number by controlling the bubble nucleus formation rate. In addition, the cell diameter and the bubble density can be easily controlled.
　樹脂組成物の発泡又は成形する際のバッチ方式におけるガス含浸工程又は連続方式における混練含浸工程で、高圧のガスを未発泡樹脂成形体又は樹脂組成物に含浸させるときの温度は、用いるガス又は樹脂の種類等によって異なる。この温度は、広い範囲で選択でき、操作性等を考慮した場合、好ましくは１０～３５０℃である。例えば、バッチ方式において、シート状の未発泡樹脂成形体に高圧のガスを含浸させる場合の含浸温度は、好ましくは１０～２５０℃、より好ましくは４０～２４０℃、さらにより好ましくは６０～２３０℃である。また、連続方式において、樹脂組成物に高圧のガスを注入し混練する際の温度は、好ましくは６０～３５０℃、より好ましくは１００～３２０℃、さらにより好ましくは１５０～３００℃である。高圧のガスとして二酸化炭素を用いる場合には、超臨界状態を保持するため、含浸時の温度（含浸温度）は３２℃以上（特に４０℃以上）であることが好ましい。 In the gas impregnation step in the batch method or the kneading impregnation step in the continuous method when foaming or molding the resin composition, the temperature when impregnating the non-foamed resin molded product or resin composition with the high-pressure gas is the gas or resin used. It depends on the type. This temperature can be selected within a wide range, and is preferably 10 to 350 ° C. in consideration of operability and the like. For example, in a batch method, the impregnation temperature when impregnating a sheet-like unfoamed resin molded body with a high-pressure gas is preferably 10 to 250 ° C., more preferably 40 to 240 ° C., and even more preferably 60 to 230 ° C. It is. In the continuous method, the temperature at which high-pressure gas is injected into the resin composition and kneaded is preferably 60 to 350 ° C., more preferably 100 to 320 ° C., and even more preferably 150 to 300 ° C. When carbon dioxide is used as the high-pressure gas, the temperature during impregnation (impregnation temperature) is preferably 32 ° C. or higher (particularly 40 ° C. or higher) in order to maintain a supercritical state.
　バッチ方式や連続方式で樹脂組成物を発泡・成形する際の減圧工程での減圧速度は、特に限定されないが、均一な微細気泡を得るため、好ましくは５～３００ＭＰａ／秒である。加熱工程での加熱温度は、例えば、４０～２５０℃（好ましくは６０～２５０℃）である。 The pressure reduction rate in the pressure reduction step when foaming and molding the resin composition in a batch method or a continuous method is not particularly limited, but is preferably 5 to 300 MPa / second in order to obtain uniform fine bubbles. The heating temperature in the heating step is, for example, 40 to 250 ° C. (preferably 60 to 250 ° C.).
　樹脂組成物の発泡又は成形する際に上記の方法を用いると、高発泡の樹脂発泡体を製造することができ、厚い樹脂発泡体を製造することが可能となる。例えば、連続方式で樹脂組成物の発泡又は成形する場合、混練含浸工程において押出し機内部での圧力を保持するためには、押出し機先端に取り付けるダイスのギャップはできるだけ狭く（通常０．１～１．０ｍｍ程度）設定される。従って、厚い樹脂発泡体を得るためには、狭いギャップを通して押出された樹脂組成物を高い倍率で発泡させることが好ましい。しかし、従来は、高い発泡倍率が得られないことから、形成される樹脂発泡体の厚みは薄いもの（例えば０．５～２．０ｍｍ）に限定されていた。これに対して、本発明では、高圧のガスを用いて樹脂組成物を発泡又は成形することにより、最終的に０．５０～５．００ｍｍの厚みの樹脂発泡体を連続して得ることが可能である。 When the above method is used when foaming or molding the resin composition, a highly foamed resin foam can be produced, and a thick resin foam can be produced. For example, when the resin composition is foamed or molded in a continuous manner, the gap between the dies attached to the tip of the extruder is as narrow as possible (usually 0.1 to 1 in order to maintain the pressure inside the extruder in the kneading impregnation step. About 0 mm). Therefore, in order to obtain a thick resin foam, it is preferable to foam the resin composition extruded through a narrow gap at a high magnification. However, conventionally, since a high foaming ratio cannot be obtained, the thickness of the formed resin foam is limited to a thin one (for example, 0.5 to 2.0 mm). In contrast, in the present invention, a resin foam having a thickness of 0.50 to 5.00 mm can be continuously obtained by foaming or molding a resin composition using a high-pressure gas. It is.
　本発明の樹脂発泡体は、凹み回復率、厚み回復率、歪回復率、平均セル径、圧縮時反発応力、見掛け密度、相対密度等を、用いるガス、熱可塑性樹脂やゴム成分及び／又は熱可塑性エラストマー成分などの種類に応じて、例えば、ガス含浸工程や混練含浸工程における温度、圧力、時間などの操作条件、減圧工程や成形減圧工程における減圧速度、温度、圧力などの操作条件、減圧後又は成形減圧後の加熱工程における加熱温度などを適宜選択、設定することでも調整することができる。 The resin foam of the present invention has a dent recovery rate, a thickness recovery rate, a strain recovery rate, an average cell diameter, a repulsion stress during compression, an apparent density, a relative density, and the like, a gas, a thermoplastic resin, a rubber component, and / or a heat. Depending on the type of plastic elastomer component, etc., for example, operating conditions such as temperature, pressure and time in the gas impregnation process and kneading impregnation process, operating conditions such as the decompression speed, temperature and pressure in the decompression process and molding decompression process, after decompression Or it can also adjust by selecting and setting suitably the heating temperature etc. in the heating process after shaping | molding pressure reduction.
　特に、本発明の樹脂発泡体は、熱可塑性樹脂に加えて、造核剤、脂肪族系化合物を少なくとも含む樹脂組成物に、高圧のガス（特に不活性ガス）を含浸させた後、減圧する工程を経て形成されていることが好ましい。これによって、平均セル径が小さく、独立気泡構造率が低い気泡構造を有し、高発泡倍率であり、良好な柔軟性を有し、気泡構造が変形又は圧縮しにくく、押圧したときの歪回復性に優れ、加工性に優れる樹脂発泡体を容易に得ることができる。 In particular, the resin foam of the present invention is decompressed after impregnating a resin composition containing at least a nucleating agent and an aliphatic compound in addition to a thermoplastic resin with a high-pressure gas (particularly an inert gas). It is preferably formed through a process. As a result, the cell structure has a small average cell diameter, a low closed cell structure ratio, a high expansion ratio, good flexibility, the bubble structure is difficult to deform or compress, and strain recovery when pressed The resin foam having excellent properties and processability can be easily obtained.
　本発明の樹脂発泡体は、熱可塑性樹脂に加えて、平均粒径が特に小さい造核剤、脂肪族系化合物を少なくとも含む樹脂組成物に、超臨界状態の不活性ガスを含浸させた後、減圧する工程を経て形成されていることがより好ましい。これにより、平均セル径が極めて小さく、独立気泡構造率が低い気泡構造を有し、高発泡倍率であり、良好な柔軟性を有し、気泡構造が変形又は圧縮しにくく、押圧したときの歪回復性に優れ、造核剤が気泡壁を突き破ることをより抑制できる。よって、より加工性に優れる樹脂発泡体を容易に得ることができる。 The resin foam of the present invention is obtained by impregnating a supercritical inert gas with a resin composition containing at least a nucleating agent having a particularly small average particle diameter and an aliphatic compound in addition to a thermoplastic resin. More preferably, it is formed through a pressure reducing step. As a result, the average cell diameter is extremely small, the cell structure ratio is low, the cell structure is high, the foaming ratio is high, the flexibility is good, the cell structure is difficult to deform or compress, and the strain when pressed It has excellent recoverability and can further suppress the nucleating agent from breaking through the bubble wall. Therefore, the resin foam which is more excellent in workability can be obtained easily.
　本発明の樹脂発泡体は、熱可塑性樹脂とゴム成分及び／又は熱可塑性エラストマー成分の混合物であり、その割合が、重量基準で、７０／３０～３０／７０である熱可塑性樹脂に加えて、該熱可塑性樹脂１００重量部に対して０．５～１５０重量部の造核剤、該熱可塑性樹脂１００重量部に対して１～５重量部の脂肪族系化合物を少なくとも含む樹脂組成物に、高圧のガス（特に不活性ガス）を含浸させた後、減圧する工程を経て形成されていることが好ましい。 The resin foam of the present invention is a mixture of a thermoplastic resin and a rubber component and / or a thermoplastic elastomer component, the ratio of which is 70/30 to 30/70 on a weight basis, A resin composition containing at least 0.5 to 150 parts by weight of a nucleating agent with respect to 100 parts by weight of the thermoplastic resin and 1 to 5 parts by weight of an aliphatic compound with respect to 100 parts by weight of the thermoplastic resin, It is preferably formed through a step of depressurizing after impregnating with a high-pressure gas (particularly an inert gas).
　〔発泡シール材〕
　本発明の発泡シール材は、上記樹脂発泡体を含む部材である。発泡シール材の形状は、特に限定されず、シート状（フィルム状を含む）が好ましい。発泡シール材は、例えば、樹脂発泡体のみからなる構成であってもよいし、樹脂発泡体に、粘着剤層、基材層などが積層されている構成であってもよい。 [Foamed sealing material]
The foam sealing material of this invention is a member containing the said resin foam. The shape of the foam sealing material is not particularly limited, and a sheet shape (including a film shape) is preferable. For example, the foamed sealing material may be configured only by a resin foam, or may be configured such that an adhesive layer, a base material layer, and the like are laminated on the resin foam.
　特に、本発明の発泡シール材は、粘着材層を有することが好ましい。例えば、本発明の発泡シール材がシート状の発泡シール材である場合、その片面又は両面に粘着材層を有していてもよい。発泡シール材が粘着材層を有していると、例えば、発泡シール材上に粘着材層を介して加工用台紙を設けることができ、さらに、被着体へ固定、仮止め等することができる。 In particular, the foamed sealing material of the present invention preferably has an adhesive layer. For example, when the foamed sealing material of the present invention is a sheet-like foamed sealing material, it may have an adhesive layer on one or both sides. When the foamed sealing material has an adhesive material layer, for example, a processing mount can be provided on the foamed sealing material via the adhesive material layer, and further, fixed to the adherend, temporarily fixed, etc. it can.
　粘着材層を形成する粘着剤としては、特に限定されず、例えば、アクリル系粘着剤、ゴム系粘着剤（天然ゴム系粘着剤、合成ゴム系粘着剤など）、シリコーン系粘着剤、ポリエステル系粘着剤、ウレタン系粘着剤、ポリアミド系粘着剤、エポキシ系粘着剤、ビニルアルキルエーテル系粘着剤、フッ素系粘着剤などの公知の粘着剤を適宜選択して用いることができる。粘着剤は、単独で又は２種以上組み合わせて使用することができる。なお、粘着剤は、エマルジョン系粘着剤、溶剤系粘着剤、ホットメルト型粘着剤、オリゴマー系粘着剤、固系粘着剤などのいずれの形態の粘着剤であってもよい。なかでも、粘着剤としては、被着体への汚染防止などの観点から、アクリル系粘着剤が好ましい。 The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive (such as a natural rubber-based pressure-sensitive adhesive, a synthetic rubber-based pressure-sensitive adhesive), a silicone-based pressure-sensitive adhesive, or a polyester-based pressure-sensitive adhesive. Known pressure-sensitive adhesives such as adhesives, urethane-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives can be appropriately selected and used. An adhesive can be used individually or in combination of 2 or more types. The pressure-sensitive adhesive may be any type of pressure-sensitive adhesive such as an emulsion-based pressure-sensitive adhesive, a solvent-based pressure-sensitive adhesive, a hot-melt pressure-sensitive adhesive, an oligomer-based pressure-sensitive adhesive, and a solid-type pressure-sensitive adhesive. Among these, as the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive is preferable from the viewpoint of preventing contamination of the adherend.
　粘着材層の厚みは、好ましくは２～１００μｍ、より好ましくは１０～１００μｍである。粘着材層は、薄層であるほど、端部のゴミや埃の付着を防止する効果が高いため、厚みは薄い方が好ましい。
　粘着材層は、単層、積層体のいずれの形態を有していてもよいし、発泡性又は非発泡性のいずれであってもよい。なかでも、非発泡性の粘着材層が好ましい。 The thickness of the adhesive material layer is preferably 2 to 100 μm, more preferably 10 to 100 μm. The thinner the adhesive material layer, the higher the effect of preventing dust and dirt from adhering to the edge, and thus the thinner the adhesive material layer, the better.
The pressure-sensitive adhesive layer may have any form of a single layer or a laminate, and may be foamable or non-foamable. Of these, a non-foaming pressure-sensitive adhesive layer is preferable.
　本発明の発泡シール材において、粘着材層は、他の層（下層）を介して、設けられていてもよい。このような下層としては、例えば、他の粘着材層、中間層、下塗り層、基材層（特にフィルム層、不織布層など）などが挙げられる。下層は、発泡性の層であってもよいし、多孔質の層であってもよいが、非発泡性の層であることが好ましく、樹脂層であることがより好ましい。
　粘着材層は、剥離フィルム（セパレーター）（例えば、剥離紙、剥離フィルムなど）により保護されていてもよい。 In the foamed sealing material of the present invention, the pressure-sensitive adhesive layer may be provided via another layer (lower layer). Examples of such a lower layer include other pressure-sensitive adhesive layers, intermediate layers, undercoat layers, base material layers (particularly film layers, nonwoven fabric layers, etc.) and the like. The lower layer may be a foamable layer or a porous layer, but is preferably a non-foamable layer, more preferably a resin layer.
The pressure-sensitive adhesive layer may be protected by a release film (separator) (for example, release paper, release film, etc.).
　本発明の発泡シール材は、本発明の樹脂発泡体を含むため、良好な防塵性、特に良好な動的防塵性を有し、微小なクリアランスに対して追従可能な柔軟性を有する。 Since the foamed sealing material of the present invention contains the resin foam of the present invention, it has good dust resistance, particularly good dynamic dust resistance, and has flexibility to follow a minute clearance.
　本発明の発泡シール材は、所望の形状や厚みなどを有するように加工が施されていてもよい。例えば、用いられる装置や機器、筐体、部材等に合わせて種々の形状に加工が施されていてもよい。 The foamed sealing material of the present invention may be processed so as to have a desired shape and thickness. For example, various shapes may be processed according to the device, equipment, casing, member, and the like used.
　本発明の発泡シール材は、各種部材又は部品を、所定の部位に取り付ける（装着する）際に用いられる部材として好適に用いられる。特に、本発明の発泡シール材は、電気又は電子機器において、電気又は電子機器を構成する部品を所定の部位に取り付ける（装着する）際に用いられる部材として好適である。 The foamed sealing material of the present invention is suitably used as a member used when various members or parts are attached (attached) to a predetermined site. In particular, the foamed sealing material of the present invention is suitable as a member used when attaching (attaching) a component constituting an electric or electronic device to a predetermined site in an electric or electronic device.
　発泡部材を利用して取付（装着）可能な各種部材又は部品としては、特に限定されないが、例えば、電気又は電子機器類における各種部材又は部品などが挙げられる。このような電気又は電子機器用の部材又は部品としては、例えば、液晶ディスプレイ、エレクトロルミネッセンスディスプレイ、プラズマディスプレイ等の画像表示装置に装着される画像表示部材（表示部）（特に、小型の画像表示部材）、いわゆる「携帯電話」及び「携帯情報端末」等の移動体通信の装置に装着されるカメラ及びレンズ（特に、小型のカメラ及びレンズ）等の光学部材又は光学部品などが挙げられる。 The various members or parts that can be attached (mounted) using the foamed member are not particularly limited, and examples thereof include various members or parts in electrical or electronic equipment. Examples of such a member or component for electric or electronic equipment include an image display member (display unit) (particularly a small image display member) mounted on an image display device such as a liquid crystal display, an electroluminescence display, or a plasma display. ), Optical members or optical components such as cameras and lenses (particularly small cameras and lenses) mounted on mobile communication devices such as so-called “mobile phones” and “portable information terminals”.
　本発明の発泡シール材の好適な具体的使用態様としては、例えば、防塵、遮光、緩衝等を目的として、ＬＣＤ（液晶ディスプレイ）等の表示部周り、ＬＣＤ（液晶ディスプレイ）等の表示部と筐体（窓部）との間に挟み込んで使用するものが挙げられる。
　本発明の発泡シール材を、このような部材又は部品に取り付ける場合には、そのクリアランスを塞ぐように取り付けることが好ましい。このクリアランスとしては、特に限定されず、例えば、０．０５～０．５ｍｍ程度が挙げられる。
　以下、本発明の熱可塑性樹脂発泡体及び発泡シール材を、実施例に基づいて説明する。 For example, the foamed sealing material of the present invention is preferably used around the display unit such as an LCD (liquid crystal display) and the display unit such as an LCD (liquid crystal display) and a housing for the purpose of dust prevention, light shielding, buffering, and the like. What is inserted and used between a body (window part) is mentioned.
When the foamed sealing material of the present invention is attached to such a member or part, it is preferably attached so as to close the clearance. The clearance is not particularly limited, and may be about 0.05 to 0.5 mm, for example.
Hereinafter, the thermoplastic resin foam and foamed sealing material of the present invention will be described based on examples.
　（実施例１）
　樹脂組成物として、
　ポリプロピレン　　　３５重量部、
　熱可塑性エラストマー組成物　　　６０重量部、
　滑剤　　　５重量部、
　造核剤　　　１０重量部及び
　エルカ酸アミド（融点８０～８５℃）　　　２重量部を、二軸混練機にて２００℃の温度で混練した。 Example 1
As a resin composition,
35 parts by weight of polypropylene,
60 parts by weight of a thermoplastic elastomer composition,
5 parts by weight of lubricant,
Ten parts by weight of the nucleating agent and 2 parts by weight of erucic acid amide (melting point: 80 to 85 ° C.) were kneaded at a temperature of 200 ° C. with a twin-screw kneader.
　ここで、
　ポリプロピレンは、メルトフローレート（ＭＦＲ）が０．３５ｇ／１０ｍｉｎの樹脂、
　熱可塑性エラストマー組成物は、カーボンブラックを１５．０重量％含み、ポリプロピレン（ＰＰ）とエチレン／プロピレン／５－エチリデン－２－ノルボルネン三元共重合体（ＥＰＴ）とのブレンド物（架橋型オレフィン系熱可塑性エラストマー、ＴＰＶ）、ポリプロピレン：エチレン／プロピレン／５－エチリデン－２－ノルボルネン三元共重合体＝２５：７５（重量基準）、
　滑剤は、ステアリン酸モノグリセリド１重量部にポリエチレン１０重量部を配合したマスターバッチ、
　造核剤は、平均粒子径が０．８μｍの水酸化マグネシウムである。 here,
Polypropylene is a resin having a melt flow rate (MFR) of 0.35 g / 10 min,
The thermoplastic elastomer composition contains 15.0% by weight of carbon black and is a blend of polypropylene (PP) and ethylene / propylene / 5-ethylidene-2-norbornene terpolymer (EPT) (crosslinked olefin type). Thermoplastic elastomer, TPV), polypropylene: ethylene / propylene / 5-ethylidene-2-norbornene terpolymer = 25: 75 (weight basis),
The lubricant is a master batch in which 1 part by weight of stearic acid monoglyceride is blended with 10 parts by weight of polyethylene,
The nucleating agent is magnesium hydroxide having an average particle size of 0.8 μm.
　その後、樹脂組成物をストランド状に押出し、水冷し、ペレット状に切断して成形した。
　このペレットを、日本製鋼所社製のタンデム型単軸押出機に投入し、２２０℃の雰囲気下、１４（注入後１８）ＭＰａの圧力で、二酸化炭素ガスを３．８重量％注入した。二酸化炭素ガスを十分飽和させ、発泡に適した温度まで冷却した。その後、ダイから押出して、樹脂の押し出し速度と成形速度の比率が１：１．２～２の範囲になるように調整し、樹脂発泡体（シート状）を得た。この樹脂発泡体は、独立気泡率が３２％の半連続半独立気泡構造を有していた。 Thereafter, the resin composition was extruded into strands, cooled with water, cut into pellets, and molded.
This pellet was put into a tandem type single screw extruder manufactured by Nippon Steel Works Co., Ltd., and 3.8% by weight of carbon dioxide gas was injected under an atmosphere of 220 ° C. under a pressure of 14 (18 after injection) MPa. Carbon dioxide gas was sufficiently saturated and cooled to a temperature suitable for foaming. Thereafter, the resin was extruded from a die, and the ratio of the resin extrusion speed to the molding speed was adjusted to be in the range of 1: 1.2 to 2 to obtain a resin foam (sheet-like). This resin foam had a semi-continuous semi-closed cell structure with a closed cell rate of 32%.
　（実施例２）
　日本製鋼所社製のタンデム型単軸押出機に、二酸化炭素ガスを３．７重量％注入したこと以外は、実施例１と同様にして、樹脂発泡体（シート状）を得た。 (Example 2)
A resin foam (sheet-like) was obtained in the same manner as in Example 1 except that 3.7% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
　（実施例３）
　日本製鋼所社製のタンデム型単軸押出機に、二酸化炭素ガスを３．５重量％注入したこと以外は、実施例１と同様にして、樹脂発泡体（シート状）を得た。 (Example 3)
A resin foam (sheet-like) was obtained in the same manner as in Example 1 except that 3.5% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
　（比較例１）
　樹脂組成物として、
　ポリプロピレン　　　４５重量部、
　熱可塑性エラストマー組成物　　　５５重量部、
　滑剤　　　１０重量部及び
　造核剤　　　１０重量部を、二軸混練機にて２００℃の温度で混練した。 (Comparative Example 1)
As a resin composition,
45 parts by weight of polypropylene,
55 parts by weight of a thermoplastic elastomer composition,
10 parts by weight of a lubricant and 10 parts by weight of a nucleating agent were kneaded at a temperature of 200 ° C. with a biaxial kneader.
　ここで、
　熱可塑性エラストマー組成物は、カーボンブラックを１５．０重量％含み、ポリプロピレン（ＰＰ）とエチレン／プロピレン／５－エチリデン－２－ノルボルネン三元共重合体（ＥＰＴ）とのブレンド物（ＴＰＯ）：ポリプロピレンとエチレン／プロピレン／５－エチリデン－２－ノルボルネン三元共重合体＝３０／７０（重量基準）であり、
　ポリプロピレン、滑剤及び造核剤は実施例１と同様のものを用いた。 here,
The thermoplastic elastomer composition contains 15.0% by weight of carbon black, and a blend (TPO) of polypropylene (PP) and ethylene / propylene / 5-ethylidene-2-norbornene terpolymer (EPT): polypropylene And ethylene / propylene / 5-ethylidene-2-norbornene terpolymer = 30/70 (weight basis),
The same polypropylene, lubricant and nucleating agent as in Example 1 were used.
　その後、樹脂組成物としてストランド状に押出し、水冷し、ペレット状に切断して成形した。
　このペレットを、日本製鋼所社製のタンデム型単軸押出機に投入し、２２０℃の雰囲気下、１４（注入後１８）ＭＰａの圧力で、二酸化炭素ガスを３．８重量％注入した。二酸化炭素ガスを十分飽和させ、発泡に適した温度まで冷却した。その後、ダイから押出して、樹脂発泡体（シート状）を得た。この樹脂発泡体は、独立気泡率が４６％の半連続半独立気泡構造を有していた。 Thereafter, the resin composition was extruded into a strand shape, cooled with water, cut into a pellet shape, and molded.
This pellet was put into a tandem type single screw extruder manufactured by Nippon Steel Works Co., Ltd., and 3.8% by weight of carbon dioxide gas was injected under an atmosphere of 220 ° C. under a pressure of 14 (18 after injection) MPa. Carbon dioxide gas was sufficiently saturated and cooled to a temperature suitable for foaming. Then, it extruded from the die | dye and obtained the resin foam (sheet form). This resin foam had a semi-continuous semi-closed cell structure with a closed cell ratio of 46%.
　（比較例２）
　日本製鋼所社製のタンデム型単軸押出機に、二酸化炭素ガスを３．７重量％注入したこと以外は、比較例１と同様にして、樹脂発泡体（シート状）を得た。 (Comparative Example 2)
A resin foam (sheet-like) was obtained in the same manner as in Comparative Example 1 except that 3.7% by weight of carbon dioxide gas was injected into a tandem single screw extruder manufactured by Nippon Steel Works.
　（独立気泡率の測定方法）
　実施例及び比較例で得られた樹脂発泡体の独立気泡率は、以下の方法に従って測定した。
　得られた樹脂発泡体から、一定厚みで、一辺５ｃｍの平面正方形状の試験片を切り出す。続いて、この試験片の重量Ｗ１（ｇ）及び厚み（ｃｍ）を測定して、試験片の見掛け体積Ｖ１（ｃｍ３）を算出する。
　次に、得られた値を式（１）に代入し、気泡の占める見掛け体積Ｖ２（ｃｍ３）を算出する。なお、試験片を構成する樹脂の密度をρｇ／ｃｍ３とする。
　気泡の占める見掛け体積Ｖ２＝Ｖ１－Ｗ１／ρ　　　　　（１）
　続いて、この試験片を２３℃の蒸留水中に、試験片の上面から水面までの距離が４０ｍｍとなるように沈め、２４時間放置する。その後、試験片を蒸留水中から取り出して、試験片の表面に付着した水分を除去する。得られた試験片の重量Ｗ２（ｇ）を測定し、式（２）に基づいて、連続気泡率Ｆ１を算出する。この連続気泡率Ｆ１から独立気泡率Ｆ２を求める。
　連続気泡率Ｆ１＝１００×（Ｗ２－Ｗ１）／Ｖ２ 　　　　（２）
　独立気泡率Ｆ２＝１００－Ｆ１　　　　　　　　　　　　（３）  (Measurement method of closed cell ratio)
The closed cell ratio of the resin foams obtained in Examples and Comparative Examples was measured according to the following method.
From the obtained resin foam, a flat square test piece having a constant thickness and a side of 5 cm is cut out. Subsequently, the weight W 1 (g) and thickness (cm) of the test piece are measured, and the apparent volume V 1 (cm 3 ) of the test piece is calculated.
Next, the obtained value is substituted into the equation (1), and the apparent volume V 2 (cm 3 ) occupied by the bubbles is calculated. The density of the resin constituting the test piece is ρg / cm 3 .
Apparent volume occupied by bubbles V 2 = V 1 −W 1 / ρ (1)
Subsequently, the test piece is submerged in distilled water at 23 ° C. so that the distance from the upper surface of the test piece to the water surface is 40 mm and left for 24 hours. Then, a test piece is taken out from distilled water and the water | moisture content adhering to the surface of the test piece is removed. The weight W 2 (g) of the obtained test piece is measured, and the open cell ratio F1 is calculated based on the formula (2). The closed cell rate F 2 is determined from the open cell rate F 1 .
Open cell ratio F 1 = 100 × (W 2 −W 1 ) / V 2 (2)
Closed cell ratio F 2 = 100−F 1 (3)
　（評価）
　実施例及び比較例で得られた樹脂発泡体のシートについて、それぞれの見掛け密度、５０％圧縮時の反発力、凹み回復率、平均セル径、動的防塵性及び厚み回復率を測定又は評価した。その結果を表１に示す。 (Evaluation)
With respect to the resin foam sheets obtained in Examples and Comparative Examples, the apparent density, repulsive force at 50% compression, dent recovery rate, average cell diameter, dynamic dust resistance and thickness recovery rate were measured or evaluated. . The results are shown in Table 1.
　（凹み回復率の測定方法）
　熱可塑性樹脂発泡体（幅２ｍｍ×厚さ１ｍｍ×長さ５ｃｍ）に、２３℃にて、刃角９０度の治具を１０Ｎの荷重で樹脂発泡体の厚み方向の最下点まで圧縮し、１５秒間圧縮状態を維持した。圧縮解除６０秒後の凹み部分の厚みを測定した。下記式から凹み回復率を求めた。
　　凹み回復率＝（圧縮状態解除６０秒後の凹み部分の厚み）／（初期厚み）×１００ (Measurement method of dent recovery rate)
A thermoplastic resin foam (width 2 mm × thickness 1 mm × length 5 cm) is compressed at 23 ° C. to a lowest point in the thickness direction of the resin foam with a load of 10 N at a blade angle of 90 degrees, The compression state was maintained for 15 seconds. The thickness of the dent part 60 seconds after decompression was measured. The dent recovery rate was calculated from the following formula.
Depression recovery rate = (thickness of dent 60 seconds after release of compressed state) / (initial thickness) × 100
　（見掛け密度の測定方法）
　発泡体の密度（見掛け密度）を以下のように算出した。
　各実施例及び比較例の発泡体を３０ｍｍ×３０ｍｍサイズに打ち抜き、試験片とし、試験片の寸法をノギスで測定した。次に、試験片の重量を電子天秤にて測定した。そして、次式により算出した。
　　　見掛け密度（ｇ／ｃｍ3）＝試験片の質量／試験片の体積 (Apparent density measurement method)
The density (apparent density) of the foam was calculated as follows.
The foams of each Example and Comparative Example were punched into a size of 30 mm × 30 mm to obtain test pieces, and the dimensions of the test pieces were measured with a caliper. Next, the weight of the test piece was measured with an electronic balance. And it computed by following Formula.
Apparent density (g / cm 3 ) = mass of specimen / volume of specimen
　（平均セル径の測定方法）
　樹脂発泡体のＭＤ方向（流れ方向）に対する直交方向に平行に、カッターにて樹脂発泡体の主面に対して垂直方向（厚み方向）に切断し、平滑な断面を作成した。これら断面を、デジタルマイクロスコープ（商品名「ＶＨＸ－５００」キーエンス株式会社製）により、樹脂発泡体の気泡の拡大画像を取り込み、同計測器の解析ソフト（三谷商事（株）製：Ｗｉｎ　ＲＯＯＦ）を用いて、画像解析することにより、平均セル径（μｍ）を求めた。取り込んだ拡大画像の気泡数は２００個程度であり、この２００個の平均とした。 (Measurement method of average cell diameter)
A smooth cross section was created by cutting the resin foam in a direction perpendicular to the main surface of the resin foam (thickness direction) in parallel with the direction perpendicular to the MD direction (flow direction) of the resin foam. These cross-sections are taken with a digital microscope (trade name “VHX-500”, manufactured by Keyence Corporation), and an enlarged image of the foam of the resin foam is captured. Analysis software for the measuring instrument (Mitani Corporation, Win ROOF) The average cell diameter (μm) was determined by image analysis using The number of bubbles in the captured enlarged image is about 200, and the average of these 200 was used.
　（５０％又は８０％圧縮時の対反発荷重）
　ＪＩＳ　Ｋ　６７６７に記載されている圧縮硬さ測定法に準じて測定した。
　樹脂発泡体を幅：３０ｍｍ×長さ：３０ｍｍに切り出し、シート状の試験片とした。次にこの試験片を、２３℃又は－１０℃にて、圧縮速度：１０ｍｍ／ｍｉｎで、厚さ方向に、圧縮率が５０％又は８０％に圧縮したときの応力（Ｎ）を単位面積（１ｃｍ2）当たりに換算して反発力（Ｎ／ｃｍ2）とした。
　これら５０％又は８０％圧縮時の対反発荷重は、５０％又は８０％圧縮時の反発応力あるいは５０％又は８０％圧縮荷重とも称される。 (Repulsive load at 50% or 80% compression)
It measured according to the compression hardness measuring method described in JIS K 6767.
The resin foam was cut into a width of 30 mm and a length of 30 mm to obtain a sheet-like test piece. Next, when this test piece was compressed at 23 ° C. or −10 ° C. at a compression rate of 10 mm / min in the thickness direction and the compression rate was reduced to 50% or 80%, the unit area ( The repulsive force (N / cm 2 ) was calculated per 1 cm 2 ).
These repulsive loads at 50% or 80% compression are also referred to as repulsive stresses at 50% or 80% compression or 50% or 80% compression loads.
　（厚み回復率の測定方法）
　圧縮試験機（（株）島津製作所製　マイクロサーボ）を用いて、２３℃にて、厚み方向に、初期厚み（１ｍｍ）に対して２０％の厚みに１分間圧縮し、圧縮解除し、圧縮解除１秒後の厚みの回復挙動を、高速度カメラを用いて撮影した。厚み回復率は、圧縮解除１秒後の厚みの初期厚みに対する割合として表した。 (Measurement method of thickness recovery rate)
Using a compression tester (Micro Servo, manufactured by Shimadzu Corporation), compress the sample at 23 ° C for 1 minute in the thickness direction to a thickness of 20% of the initial thickness (1 mm), release the compression, and release the compression. The recovery behavior of the thickness after 1 second was photographed using a high-speed camera. The thickness recovery rate was expressed as the ratio of the thickness after 1 second of decompression to the initial thickness.
　（歪回復率の測定方法）
　樹脂発泡体を２３℃にて、初期厚みに対して５０％の厚みに２４時間圧縮し、その圧縮状態を解除した後２４時間の厚み方向の初期厚みに対する割合とした。 (Measurement method of strain recovery rate)
The resin foam was compressed at 23 ° C. to a thickness of 50% of the initial thickness for 24 hours, and after releasing the compressed state, the ratio was set to the initial thickness in the thickness direction for 24 hours.
　（動的防塵性の評価方法）
　まず、樹脂発泡体を、図２に示す額縁状（窓枠状）（４０ｍｍ×５６ｍｍ、幅：２ｍｍ）に打ち抜き、評価用サンプル２２とした。
　この評価用サンプル２２を、図３に示す動的防塵性評価用容器２に装着した。装着時の評価サンプル２２の圧縮率は初期厚みに対して厚み方向に５０％とした。
　評価用サンプル２２は、図３に示すように、フォーム圧縮板２７を介してベース板２４にねじ２６によって取り付けられた黒色アクリル板２１１と、ベース板２４に、ピンによって固定され、アルミニウムスペーサ２３上に配置する黒色アクリル板２１２との間に設けられている。なお、評価用サンプル２２の圧縮率は、アルミスペーサー２３の厚み調整により、調整することができる。評価用サンプル２２を装着した評価用容器２では、評価用サンプル２２により、一定の内部空間２９が閉塞された系となっている。
　また、評価用容器２では、評価用サンプル２２よりも外側に隣接して位置し、評価用サンプル２２とフォーム圧縮板２７との間に、一定の外部空間２５が閉塞された粉末供給部として構成されている。この外部空間２５には、粉塵にみたてた粉末（例えば、粒径１７μｍのコンスターチ）が０．１ｇ充填されている。
　このような評価用容器２を、図５に示す評価容器をダンブラー１（回転槽、ドラム式落下試験器）に入れ、１ｒｐｍの速度で回転させた。そして、評価用容器２で１００回の衝突回数（繰り返し衝撃）が得られるように、所定回数を回転させた。その後、パッケージを分解した。そして、粉末供給部である外部空間２５から、評価用サンプル２２を通過して、内部空間の上下壁として機能させた黒色アクリル板２１１及び黒色アクリル板２１２に付着した粒子を、デジタルマイクロスコープ（装置名「ＶＨＸ－６００」、キーエンス株式会社製）で観察した。
　黒色アクリル板２１１及び黒色アクリル板２１２について静止画像を作成し、画像解析ソフト（ソフト名「Ｗｉｎ　ＲＯＯＦ」、三谷商事株式会社製）を用いて２値化処理を行い、コンスターチの粒子の個数をカウントした。なお、観察は、空気中の浮遊粉塵の影響を少なくするためクリーンベンチ内で行った。 (Dynamic dustproof evaluation method)
First, the resin foam was punched into a frame shape (window frame shape) (40 mm × 56 mm, width: 2 mm) shown in FIG.
This evaluation sample 22 was attached to the dynamic dustproof evaluation container 2 shown in FIG. The compression rate of the evaluation sample 22 at the time of mounting was 50% in the thickness direction with respect to the initial thickness.
As shown in FIG. 3, the evaluation sample 22 is fixed to the base plate 24 with a black acrylic plate 211 attached to the base plate 24 via a foam compression plate 27 by screws 26, and fixed on the aluminum spacer 23. It is provided between the black acrylic board 212 arrange | positioned in this. The compression rate of the evaluation sample 22 can be adjusted by adjusting the thickness of the aluminum spacer 23. The evaluation container 2 to which the evaluation sample 22 is attached has a system in which a certain internal space 29 is closed by the evaluation sample 22.
The evaluation container 2 is configured as a powder supply unit that is positioned adjacent to the outside of the evaluation sample 22 and in which a constant external space 25 is closed between the evaluation sample 22 and the foam compression plate 27. Has been. The external space 25 is filled with 0.1 g of powdered dust (for example, a starch having a particle diameter of 17 μm).
Such an evaluation container 2 was rotated at a speed of 1 rpm by putting the evaluation container shown in FIG. 5 into a dumbler 1 (rotary tank, drum type drop tester). Then, the evaluation container 2 was rotated a predetermined number of times so that 100 collisions (repetitive impact) were obtained. Thereafter, the package was disassembled. And the particle | grains which passed the sample 22 for evaluation from the external space 25 which is a powder supply part, and were made to function as the upper and lower walls of internal space were attached to the digital microscope (device) Name “VHX-600” (manufactured by Keyence Corporation).
Still images are created for the black acrylic plate 211 and the black acrylic plate 212, and binarization processing is performed using image analysis software (software name “Win ROOF”, manufactured by Mitani Corp.), and the number of particles of the starch is counted. did. The observation was performed in a clean bench to reduce the influence of airborne dust.
Figure JPOXMLDOC01-appb-T000001
      
Figure JPOXMLDOC01-appb-T000001
      
　表１によれば、実施例１～３の樹脂発泡体は、凹み回復率が５０％以上であることから、凹み回復率が５０％以下の比較例に対して、良好な動的防塵性得られることが確認された。
　特に、厚み回復率が良好であっても、さらに、凹み回復率が良好である場合には、迅速な樹脂発泡体の凹みの回復を期待することができ、より一層の動的防塵性をもたらすことが確認された。 According to Table 1, since the resin foams of Examples 1 to 3 have a dent recovery rate of 50% or more, good dynamic dustproof properties can be obtained compared to the comparative example having a dent recovery rate of 50% or less. It was confirmed that
In particular, even if the thickness recovery rate is good, if the dent recovery rate is also good, it is possible to expect rapid recovery of the dents of the resin foam, resulting in further dynamic dust resistance It was confirmed.
　本発明は、電子機器等の内部絶縁体、緩衝材、遮音材、防塵材、衝撃吸収材、遮光材、断熱材、食品包装材、衣用材、建材用等として有用な、クッション性及び歪回復性に優れ、高発泡倍率を有する樹脂発泡体及び発泡シール材であり、特に、携帯電話、携帯型情報端末機、ＬＣＤ等の表示部周り等、より詳細には、ＬＣＤと筐体（窓部）との間など、種々の部材に広く利用することができる。 The present invention is useful as an internal insulator for electronic devices, cushioning materials, sound insulating materials, dustproof materials, shock absorbing materials, light shielding materials, heat insulating materials, food packaging materials, clothing materials, building materials, etc., cushioning properties and strain recovery Resin foam and foam sealing material with excellent foaming ratio and high foaming ratio, especially around the display part of mobile phones, portable information terminals, LCDs, etc. ) Can be widely used for various members.
　１　タンブラー
　２　動的防塵性評価用容器
　２２　評価用サンプル
　２４　ベース板
　２６　ねじ
　２７　フォーム圧縮板
　２１１、２１２　黒色アクリル板
　２３　アルミニウムスペーサ
　２９　内部空間
　２５　外部空間 DESCRIPTION OF SYMBOLS 1 Tumbler 2 Dynamic dustproof evaluation container 22 Evaluation sample 24 Base plate 26 Screw 27 Foam compression plate 211, 212 Black acrylic plate 23 Aluminum spacer 29 Internal space 25 External space

Claims (10)

  1. 　下記で定義される２３℃での凹み回復率が５０％以上であることを特徴とする熱可塑性樹脂発泡体。
    　凹み回復率：熱可塑性樹脂発泡体を、刃角９０度の治具によって、前記発泡体の厚み方向の最下点まで圧縮して１５秒間維持した後、圧縮状態を解除し、圧縮状態解除６０秒後の凹み部分の厚みの初期厚みに対する割合。     A thermoplastic resin foam characterized by having a dent recovery rate at 23 ° C. defined below of 50% or more.
    Depression recovery rate: The thermoplastic resin foam was compressed to the lowest point in the thickness direction of the foam with a jig having a blade angle of 90 degrees and maintained for 15 seconds, then the compressed state was released, and the compressed state was released 60 The ratio of the thickness of the dent after 2 seconds to the initial thickness.
  2. 　平均セル径が１０～２００μｍであり、見掛け密度が０．０１～０．２０ｇ／ｃｍ3である請求項１記載の熱可塑性樹脂発泡体。 2. The thermoplastic resin foam according to claim 1, wherein the average cell diameter is 10 to 200 μm and the apparent density is 0.01 to 0.20 g / cm 3 .
  3. 　下記で定義される２３℃での５０％圧縮時の反発応力が０．１～３．０Ｎ／ｃｍ2である請求項１又は２記載の熱可塑性樹脂発泡体。
    　５０％圧縮時の反発応力：熱可塑性樹脂発泡体を、初期厚みに対して５０％の厚みに圧縮した際の対反発荷重。     The thermoplastic resin foam according to claim 1 or 2, wherein the rebound stress at 50% compression at 23 ° C defined below is 0.1 to 3.0 N / cm 2 .
    Repulsive stress at 50% compression: Repulsive load when a thermoplastic resin foam is compressed to 50% of the initial thickness.
  4. 　高圧ガスが含浸された熱可塑性樹脂組成物の減圧処理によって得られる請求項１～３のいずれか１つに記載の熱可塑性樹脂発泡体。 The thermoplastic resin foam according to any one of claims 1 to 3, obtained by decompression treatment of a thermoplastic resin composition impregnated with a high-pressure gas.
  5. 　前記ガスが、不活性ガスである請求項４記載の熱可塑性樹脂発泡体。 The thermoplastic resin foam according to claim 4, wherein the gas is an inert gas.
  6. 　前記不活性ガスが、二酸化炭素又は窒素である請求項５記載の熱可塑性樹脂発泡体。 The thermoplastic resin foam according to claim 5, wherein the inert gas is carbon dioxide or nitrogen.
  7. 　前記ガスが、超臨界状態のガスである請求項４～６のいずれか１つに記載の熱可塑性樹脂発泡体。 The thermoplastic resin foam according to any one of claims 4 to 6, wherein the gas is a gas in a supercritical state.
  8. 　請求項１～７のいずれか１つに記載の熱可塑性樹脂発泡体を含むことを特徴とする発泡シール材。 A foamed sealing material comprising the thermoplastic resin foam according to any one of claims 1 to 7.
  9. 　熱可塑性樹脂発泡体の片面又は両面に配置された粘着材層を備える請求項８記載の発泡シール材。 The foaming sealing material of Claim 8 provided with the adhesive material layer arrange | positioned at the single side | surface or both surfaces of the thermoplastic resin foam.
  10. 　粘着材層が、フィルム層を介して、熱可塑性樹脂発泡体表面に配置されている請求項９記載の発泡シール材。 The foamed sealing material according to claim 9, wherein the adhesive material layer is disposed on the surface of the thermoplastic resin foam via the film layer.
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