WO2015132812A1 - フィルム及びラベル付きプラスチック容器 - Google Patents
フィルム及びラベル付きプラスチック容器 Download PDFInfo
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- WO2015132812A1 WO2015132812A1 PCT/JP2014/001156 JP2014001156W WO2015132812A1 WO 2015132812 A1 WO2015132812 A1 WO 2015132812A1 JP 2014001156 W JP2014001156 W JP 2014001156W WO 2015132812 A1 WO2015132812 A1 WO 2015132812A1
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- WIPO (PCT)
- Prior art keywords
- film
- porous layer
- layer
- thermoplastic resin
- mass
- Prior art date
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Classifications
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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
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
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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
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
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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
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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- 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
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
- B29C2045/1486—Details, accessories and auxiliary operations
- B29C2045/14901—Coating a sheet-like insert smaller than the dimensions of the adjacent mould wall
- B29C2045/14918—Coating a sheet-like insert smaller than the dimensions of the adjacent mould wall in-mould-labelling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
- B29C45/14778—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles the article consisting of a material with particular properties, e.g. porous, brittle
- B29C45/14811—Multilayered articles
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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
- B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
- B32B2262/10—Inorganic fibres
- B32B2262/101—Glass fibres
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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
- B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
- B32B2264/10—Inorganic particles
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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
- B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
- B32B2264/10—Inorganic particles
- B32B2264/102—Oxide or hydroxide
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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
- B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
- B32B2264/10—Inorganic particles
- B32B2264/104—Oxysalt, e.g. carbonate, sulfate, phosphate or nitrate particles
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/304—Insulating
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/306—Resistant to heat
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/514—Oriented
- B32B2307/516—Oriented mono-axially
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/72—Density
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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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/75—Printability
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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
- B32B2439/00—Containers; Receptacles
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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
- B32B2519/00—Labels, badges
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- 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
- C08J2323/04—Homopolymers or copolymers of ethene
- C08J2323/06—Polyethene
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- 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
- C08J2423/04—Homopolymers or copolymers of ethene
- C08J2423/08—Copolymers of ethene
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
- Y10T428/1376—Foam or porous material containing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
- Y10T428/2495—Thickness [relative or absolute]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249982—With component specified as adhesive or bonding agent
- Y10T428/249983—As outermost component
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249986—Void-containing component contains also a solid fiber or solid particle
Definitions
- the present invention relates to a thermoplastic resin film. More specifically, the present invention relates to a thermoplastic resin film having excellent heat insulating properties and a labeled plastic container formed by sticking the thermoplastic resin film by in-mold molding.
- An in-mold label containing an ⁇ -olefin copolymer (Patent Document 3) and a thermoplastic resin film mainly containing polyethyleneimine (Patent Document 4) are known.
- Patent Literature [Patent Document 1] US Pat. No. 4,837,075
- Patent Document 3 Japanese Patent Laid-Open No. 9-207166
- Patent Document 4 Japanese Patent Laid-Open No. 2000-290411 Gazette
- ⁇ Adhesion failure may occur depending on the combination of the type of in-mold molding method and the material of the in-mold label.
- a first aspect of the present invention is a film containing a thermoplastic resin, wherein the film has at least one porous layer that satisfies the following conditions (A) and (B): A film is provided.
- the porous layer contains 25 to 65 parts by mass of a thermoplastic resin and 35 to 75 parts by mass of an inorganic fine powder.
- the pore length L of the porous layer represented by the following formula (1) is 20 ⁇ m or more.
- L d ⁇ ( ⁇ 0 ⁇ ) / ⁇ 0
- L is the pore length [ ⁇ m]
- d is the thickness [ ⁇ m] of the porous layer
- ⁇ is the density [g / cm 3 ] of the porous layer
- ⁇ 0 is the true density [g / cm 3 ] of the porous layer.
- the above film may further satisfy the following condition (C).
- C The thickness d of the porous layer is 10 to 100% of the thickness D of the film.
- the porous layer may contain 0.1 to 5 parts by mass of additives with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder.
- the maximum distance from the surface of the inorganic fine powder to the pore wall in a cross section parallel to the thickness direction of the porous layer may be 50 ⁇ m or less.
- the porosity p represented by the formula (2) of the porous layer may be 15 to 75%.
- p ( ⁇ 0 ⁇ ) / ⁇ 0 ⁇ 100 (2)
- p is the porosity of the porous layer [%]
- ⁇ is the density of the porous layer [g / cm 3 ]
- ⁇ 0 is the true density of the porous layer [g / cm cm 3 ].
- the thermoplastic resin contained in the porous layer may contain polyolefin as a main component.
- the porous layer may be a layer formed by stretching in at least one axial direction.
- the thickness D of the film may be 40 to 250 ⁇ m.
- the surface resistivity R s of at least one surface of the film may be 1 ⁇ 10 8 to 1 ⁇ 10 12 ⁇ at 23 ° C. and 50% RH.
- the film may further include a surface layer disposed on one side of the porous layer. In the above film, information may be printed on the surface of the layer disposed on one side of the porous layer of the film.
- the film may further include an adhesive layer disposed on one surface side of the porous layer.
- the Oken-type smoothness s measured by JIS P 8119: 1998 on the surface of the adhesive layer may be 5 to 4000 seconds.
- the film may further include a surface layer disposed on the other surface side of the porous layer.
- information may be printed on the surface of the layer disposed on the other surface side of the porous layer of the film.
- the surface resistivity R s of the surface on the other side of the porous layer of the film may be 1 ⁇ 10 12 ⁇ or more at 23 ° C. and 50% RH.
- the thermal resistance R t represented by Formula (3) below the film may 0.05m 2 ⁇ K / W or more.
- R t D ⁇ 10 ⁇ 6 / ⁇ (3)
- Rt is the thermal resistance value [m 2 ⁇ K / W] of the film
- D is the thickness [ ⁇ m] of the film
- ⁇ is the thermal conductivity [W / m ⁇ K of the film]. ].
- a plastic container with a label formed by attaching the above film by in-mold molding is provided.
- the labeled plastic container may satisfy the relationship of the following formula (4).
- Tv is the melting point of the thermoplastic resin contained in the outermost surface of the container body of the labeled plastic container
- Tf is the melting point of the thermoplastic resin contained in the layer in contact with the container body of the film.
- a third aspect of the present invention is a film containing a thermoplastic resin, the film having at least one porous layer, the porous layer comprising 25 to 65 parts by mass of a thermoplastic resin, A porous film comprising 35 to 75 parts by mass of an inorganic fine powder and having a porosity p expressed by the following formula (2) of 15 to 75% is provided.
- p ( ⁇ 0 ⁇ ) / ⁇ 0 ⁇ 100 (2)
- p is the porosity of the porous material [%]
- ⁇ is the density of the porous layer [g / cm 3 ]
- ⁇ 0 is the true density of the porous layer. [G / cm 3 ].
- the value R t is a film which is characterized in that at 0.05m 2 ⁇ K / W or more is provided.
- R t D ⁇ 10 ⁇ 6 / ⁇ (3)
- R t is a thermal resistance value [m 2 ⁇ K / W] of the film
- D is a thickness [ ⁇ m] of the film
- ⁇ is a thermal conductivity [W of the film [W]. / M ⁇ K].
- the in-mold label has at least one porous layer, and the porous layer contains 25 to 65 parts by mass of a thermoplastic resin and 35 to 75 parts by mass of an inorganic fine powder. Is provided.
- a label with good adhesion to the container body can be provided.
- the label is attached to the container body by in-mold molding, it is possible to provide a label that hardly causes orange peel.
- the labeled plastic container has a container body and a label.
- the label is formed, for example, by sticking a film to the container body.
- the labeled plastic container of the present embodiment is produced by, for example, an in-mold molding method. More specifically, after a film (sometimes referred to as an in-mold label) is placed on the inner surface of the mold, a thermoplastic resin composition in a moldable state is injected into the mold. Produced. Examples of the in-mold molding method include a blow molding method and an injection molding method.
- a film is placed at an appropriate position in the mold.
- a preform or a parison made of the thermoplastic resin composition is prepared.
- compressed gas is blown into the preform or parison to expand the preform or parison in the mold.
- the plastic container with a label is obtained by cooling a molded article.
- the resin forming the container body is in a molten state (sometimes referred to as a molten resin) and is in contact with the film forming the label.
- a molten resin sometimes referred to as a molten resin
- the film is adhered to the container body by being cooled and solidified. Therefore, if the heat insulating property of the film is insufficient, the heat transferred from the molten resin to the film is transferred to the mold, and the resin present on the surface of the film on the container body side cannot be sufficiently dissolved.
- the film and the container main body may not be bonded at all, or even if the film and the container main body are bonded, an adhesive strength sufficient for practical use may not be obtained.
- an in-mold label a laminate having a base material layer made of a porous film mainly composed of a thermoplastic resin and an adhesive layer.
- the “main component” means a component having a content of 50% by mass or more in the total content (100% by mass) of the contained components.
- a synthetic paper containing a thermoplastic resin composition containing a large amount of inorganic substance powder is known.
- 60 mass% to 82 mass% inorganic substance powder, 18 mass% to 40 mass% thermoplastic resin, and 0.05 mass% to 4.0 mass% are known.
- a raw material containing an auxiliary agent is extruded by a T-die method through a die to form a thin film sheet intermediate, and the thin film sheet intermediate is stretched at a specific draw ratio to adjust the apparent specific gravity. Is disclosed.
- thermoplastic resin composition containing a large amount of an inorganic substance is used for applications that make use of its heat transfer properties.
- a thermoplastic resin composition containing a large amount of fine inorganic powder is used for the purpose of improving the heat dissipation of the casing of a mobile phone.
- Japanese Patent Application Laid-Open No. 2013-010931 also mentions printability, processability and water resistance of synthetic paper, but does not describe or suggest heat insulation.
- many uses are described as a use of a synthetic paper, the use by which heat insulation is requested
- the present inventors have found that in a film having a porous layer containing a relatively large amount of inorganic fine powder, the porosity of the porous layer (sometimes referred to as porosity), voids. It was found that the film can be used as an in-mold label by adjusting at least one of the hole length and thermal conductivity, and the thermal conductivity and thermal resistance of the film. In addition, the present inventors have found that the adhesiveness between the in-mold label and the container body and the suppression of orange peel can be achieved by using the film as an in-mold label.
- thermoplastic resin film having excellent heat insulation and containing a large amount of inorganic substance powder is used as an in-mold label.
- the adhesiveness of an in-mold label and a container main body and suppression of orange peel can be made compatible.
- the plastic container with a label excellent in the adhesive strength between an in-mold label and a container main body is obtained.
- there is almost no generation of orange peel and a labeled plastic container excellent in aesthetics can be obtained.
- the film can be adhered to the container body at the same time as the container body of the plastic container is molded. Therefore, it is possible to easily manufacture a plastic container with a label in a short time while maintaining the designability, weight reduction, and productivity of the container body.
- the amount of heat transferred from the thermoplastic resin composition to the film is less than when producing a plastic container with a label by the injection molding method. Therefore, compared with the case where a plastic container with a label is produced by an injection molding method, adhesion failure is likely to occur.
- thermoplastic resin film having excellent heat insulation and containing a large amount of inorganic powder is used as an in-mold label.
- the adhesiveness of an in-mold label improves.
- a plastic container with a label is manufactured by a blow molding method, poor adhesion can be suppressed.
- the material of the container body is not particularly limited, and a known material can be used.
- the molding method of the container body is not particularly limited, and a known molding method can be used.
- the material of the container body may be a material that can mold the hollow container.
- a thermoplastic resin is used as a material of the container body.
- the thermoplastic resin include polyethylene terephthalate (PET) or a copolymer thereof, polyester resins such as polycarbonate resin; polyolefin resins such as polypropylene (PP) and polyethylene (PE).
- PET polyethylene terephthalate
- PET polyester resins
- polyolefin resins such as polypropylene (PP) and polyethylene (PE).
- PP polypropylene
- PE polyethylene
- a polyolefin-based resin is preferably used as a material for the container body.
- a thermoplastic resin composition containing the above thermoplastic resin as a main component may be used.
- the material of the container body may be selected to satisfy the following formula: Thereby, the adhesive force between an in-mold label and a plastic container can be improved more.
- Tf is the melting point of the thermoplastic resin contained on the surface of the container body of the plastic container.
- Tf is the melting point of the thermoplastic resin contained on the surface of the film in contact with the container body.
- Tf is the melting point of a thermoplastic resin contained in the porous layer described later, even if the in-mold label does not have an adhesive layer on the surface of the porous body on the container body side, Blister and orange peel can be suppressed.
- the film has at least one porous layer.
- the film may further include a surface layer disposed on one side of the porous layer.
- the film may further have a surface coating layer disposed on one side of the porous layer.
- the film may further include an adhesive layer disposed on one side of the porous layer.
- at least one of the surface layer and the surface coating layer may be disposed on the side of the porous layer on which the adhesive layer is not disposed.
- the adhesive layer may be disposed in contact with one surface of the porous layer.
- the surface layer or the surface coating layer may be disposed in contact with the other surface of the porous layer.
- the porous layer includes a thermoplastic resin and an inorganic fine powder.
- the porous layer may contain an additive.
- Thermoplastic resin If the thermoplastic resin contained in a porous layer is a material which can be shape
- Functional group-containing polyolefin resins such as ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, maleic acid-modified polyethylene, maleic acid-modified polypropylene; atactic polystyrene, syndiotactic polystyrene, styrene-maleic acid copolymer Styrenic resins such as polyethylene terephthalate, polyethylene terephthalate isophthalate, polybutylene terephthalate, polybutylene succinate, polybutylene adipate, esters of polylactic acid, polycarbonate, etc. Resins; nylon-6, an amide-based resin such as nylon-6,6; a mixture of two or more of these resins and the like.
- the thermoplastic resin contained in the porous layer preferably contains an olefin resin as a main component.
- the olefin resin may be a homopolymer of olefin, a copolymer of two or more olefins, or a copolymer of olefin and a monomer copolymerizable with olefin.
- Monomers that can be copolymerized with olefins include ⁇ -olefins such as 1-butene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, acrylic acid, maleic anhydride, and the like. Can be mentioned.
- the copolymer may be a random copolymer or a block copolymer.
- the olefin resin may be a polyethylene resin or a propylene resin.
- the olefin resin may be a graft-modified olefin resin.
- the graft modification method include a method of reacting an olefin resin or a functional group-containing olefin resin with an unsaturated carboxylic acid or a derivative thereof in the presence of an oxidizing agent.
- the oxidizing agent include peracids such as peracetic acid, persulfuric acid, and potassium persulfate, and metal salts thereof; ozone and the like.
- the graft modification rate may be 0.005 to 10% by mass, preferably 0.01 to 5% by mass, based on the olefin resin or the functional group-containing olefin resin.
- thermoplastic resins By mixing and using two or more kinds of thermoplastic resins as the thermoplastic resin contained in the porous layer, fluidity and moldability when the thermoplastic resin is formed into a film shape are improved.
- the fluidity of the kneaded melt of the thermoplastic resin and the inorganic fine powder is reduced, thereby forming the porous layer. May be difficult.
- thermoplastic resins with different viscosities even when a large amount of inorganic fine powder is blended with the thermoplastic resin, it is possible to suppress a decrease in fluidity of the kneaded melt of the thermoplastic resin and the inorganic fine powder. it can.
- an ultrahigh molecular weight thermoplastic resin is blended with a thermoplastic resin as a main component, or a resin having a melting point lower by 10 ° C. or more than a thermoplastic resin (for example, HDPE) as a main component.
- a thermoplastic resin for example, HDPE
- the content of the thermoplastic resin in the porous layer may be 25% by mass or more with respect to the entire porous layer. This improves the stretching stability of the porous layer when the porous layer is formed into a film.
- the content of the thermoplastic resin in the porous layer may be 28% by mass or more, preferably 30% by mass or more with respect to the entire porous layer.
- the content of the thermoplastic resin in the porous layer may be 65% by mass or less with respect to the entire porous layer. In this case, a porous layer having high opacity or whiteness can be obtained.
- the content of the thermoplastic resin in the porous layer may be 63% by mass or less, preferably 60% by mass or less, with respect to the entire porous layer.
- the inorganic fine powder contained in the porous layer includes calcium carbonate, calcined clay, silica, diatomaceous earth, white clay, talc, titanium oxide, barium sulfate, alumina, zeolite, mica, sericite, bentonite, sepiolite, vermiculite, dolomite. , One or more selected from the group consisting of wollastonite, aluminum hydroxide, glass fiber and the like.
- the porous layer contains at least one of calcium carbonate, talc, and titanium oxide, a porous layer having high opacity or whiteness can be obtained. Moreover, the moldability of the porous layer is improved. By including at least one of calcium carbonate and titanium oxide, a porous layer having further excellent effects can be obtained.
- the inorganic fine powder may be subjected to hydrophilic treatment or hydrophobic treatment on the surface of the inorganic fine powder before mixing with the thermoplastic resin.
- hydrophilic treatment or hydrophobic treatment By applying hydrophilic treatment or hydrophobic treatment to the surface of the inorganic fine powder, it is possible to impart various properties such as printability, coating suitability, scratch resistance, and secondary processing suitability to the porous layer. it can.
- the surface treatment agent include organic carboxylic acids such as fatty acids, aromatic carboxylic acids and resin acids, and salts, esters or amides thereof; organic sulfonic acids and metal salts thereof; silane coupling agents; silicone oils; Examples include polymers containing carboxyl groups, secondary to tertiary amino groups, or quaternary ammonium salts.
- oleic acid maleic acid, stearic acid and esters or amides thereof, or a polymer containing a carboxyl group or a polymer containing a quaternary ammonium salt.
- organic carboxylic acid examples include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, and other saturated fatty acids; sorbic acid, elaidic acid, palmitoleic acid Unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, celetic acid, erucic acid, ricinoleic acid, maleic acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, naphthoic acid; bietic acid, pimaric acid, parastolic acid Resin acids such as
- the organic carboxylic acid salt may be a sodium salt, potassium salt, magnesium salt, aluminum salt, calcium salt, zinc salt, tin (IV) salt, ammonium salt, diethanolamine salt, or the like.
- organic carboxylic acid ester examples include ethyl ester, vinyl ester, diisopropyl ester, cetyl ester, octyl ester, stearyl ester and the like.
- amide of the organic carboxylic acid examples include octyl amide and stearyl amide.
- organic sulfonic acid examples include alkyl sulfuric acid having an alkyl group such as lauryl, myristyl, palmitic, stearin, olein, cetyl; aromatic sulfonic acid such as naphthalenesulfonic acid and dodecylbenzenesulfonic acid; sulfosuccinic acid, dioctylsulfosuccinic acid, Examples thereof include sulfonic acid containing a carboxyl group such as lauryl sulfoacetic acid and tetradecene sulfonic acid; and polyoxyethylene alkyl ether sulfuric acid such as polyoxyethylene lauryl ether sulfuric acid and polyoxyethylene nonylphenyl ether sulfuric acid.
- the organic sulfonic acid salt may be a lithium salt, sodium salt, potassium salt, magnesium salt, calcium salt, zinc salt, aluminum salt, tin (IV) salt, ammonium salt, or the like.
- silane coupling agent examples include 3-chloropropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxy Examples include propyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane.
- silicone oil dimethyl silicone oil, methyl hydrogen polysiloxane, methyl phenyl silicone oil, cyclic dimethyl polysiloxane, and alkyl, polyether, alcohol, fluorine, amino, mercapto, epoxy, higher fatty acid, etc.
- silicone oil examples include silicone oil.
- Examples of the phosphoric acid ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, 2-ethylhexyl phosphate, triphenyl phosphate, 2-ethylhexyl diphenyl phosphate, resorcinol diphenol phosphate, bis-2-ethylhexyl phosphate, diisodecyl phosphate, 2-methacryloyloxyl.
- Examples include ethyl acid phosphate, methyl acid phosphate, butyl acid phosphate, monobutyl phosphate, 2-butylhexyl acid phosphate, polyoxyethylene lauryl ether phosphoric acid and the like.
- Examples of the polymer containing a carboxyl group, a secondary to tertiary amine group, or a quaternary ammonium salt include a monomer that gives a carboxyl group, a secondary to tertiary amino group, or a quaternary ammonium salt, and a monomer that reacts with the monomer. Or a polymer obtained by reacting a polymer containing a secondary to tertiary amino group with a quaternizing agent.
- the amount of the surface treatment agent used is preferably 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more with respect to 100 parts by mass of the inorganic fine powder. Thereby, for example, the dispersibility of the inorganic fine powder is improved.
- the amount of the surface treatment agent used is preferably 10 parts by mass or less and more preferably 5 parts by mass or less with respect to 100 parts by mass of the inorganic fine powder. Thereby, for example, a porous layer having sufficient printability or in-mold suitability is obtained.
- the content of the inorganic fine powder in the porous layer may be 35% by mass or more with respect to the entire porous layer.
- the pores of the porous layer are mainly formed around the inorganic fine powder when a resin containing the inorganic fine powder is stretched. Therefore, the number of pores in the porous layer can be increased by increasing the content of the inorganic fine powder in the porous layer. As a result, the heat insulating property of the porous layer is improved. In addition, since the number of pore walls in the porous layer increases, buckling of the porous layer at the time of in-mold molding hardly occurs.
- Content of the inorganic fine powder in a porous layer may be 40 mass% or more with respect to the whole porous layer, Preferably it is 45 mass% or more.
- the content of the inorganic fine powder in the porous layer may be 75% by mass or less with respect to the entire porous layer. Thereby, it can suppress that heat diffuses through an inorganic fine powder and the thermal conductivity of a porous layer falls too much. A porous layer having sufficient stretching properties is obtained. Content of the inorganic fine powder in a porous layer may be 70 mass% or less with respect to the whole porous layer, Preferably it is 65 mass% or less.
- the content of the inorganic fine powder in the porous layer is determined by measurement according to JIS P 8251: 2003 “Paper, paperboard and pulp—ash content test method—525 ° C. combustion method”.
- the content of the inorganic fine powder in the porous layer is calculated based on the mass of the inorganic fine powder before the surface treatment.
- the mass of the surface treatment agent used for the inorganic fine powder surface treatment is treated as the mass of an additive (for example, a dispersant or a lubricant) described later.
- the volume average particle diameter of the inorganic fine powder measured by the laser diffraction method is preferably 0.1 ⁇ m or more, and more preferably 0.3 ⁇ m or more.
- the volume average particle diameter of the inorganic fine powder is preferably 10 ⁇ m or less, and preferably 4 ⁇ m or less. Thereby, the number of pores in the porous layer can be increased. In addition, the appearance of the surface of the thermoplastic resin film is improved. For example, when the volume average particle size of the inorganic fine powder is 4 ⁇ m or less, the unevenness of the film surface becomes small, and when printing is performed on the film surface, the printing ink is uniformly transferred, and the effect of improving the printing image quality is obtained. It is done.
- the number of pores in the porous layer increases as the average particle size of the inorganic fine powder is smaller. Therefore, it is preferable that the average particle size of the inorganic fine powder is small. However, even if the average particle size of the inorganic fine powder is small, if the inorganic fine powder contains coarse particles, the pore walls in the porous layer become thin or the pores communicate with each other. The strength of the steel decreases and it becomes easy to buckle. For this reason, the inorganic fine powder preferably has a residue of 5 ppm or less in a JIS standard sieve having a mesh size of 45 ⁇ m (JIS Z 8801-1: 2006 “Test sieve—Part 1: Metal mesh sieve”). More preferably, the residue on the JIS standard sieve having an opening of 38 ⁇ m is 5 ppm or less.
- D50 and D90 of the inorganic fine powder may satisfy the relational expression 1.2 ⁇ D90 / D50 ⁇ 2.1.
- D50 is a volume-based cumulative 50% particle diameter measured by a laser diffraction method, and is also referred to as a median diameter.
- D90 is a volume-based cumulative 90% particle size measured by a laser diffraction method.
- the inorganic fine powder having a sharp particle size distribution in which the residue in a JIS standard sieve having a mesh size of 45 ⁇ m is 5 ppm or less, or D50 and D90 satisfy the above relationship can be obtained by improving the classification accuracy.
- examples of such inorganic fine powders include CUBE-13B (manufactured by Maruo Calcium Co., Ltd.), CUBE-06B (manufactured by Maruo Calcium Co., Ltd.), and BF-100 (manufactured by Bihoku Powdered Industries Co., Ltd.). .
- the pore size is smaller than that of an in-mold label having a porous film mainly composed of a thermoplastic resin as a main component.
- a porous layer having a small distribution of pore diameters and a large number of pores can be obtained.
- the porous film which has the conventional thermoplastic resin as a main component is produced by extending the thermoplastic resin shape
- the pore size in the porous layer is expressed, for example, as the maximum distance between the surface of the inorganic fine powder and the pore wall.
- the maximum distance between the surface of the inorganic fine powder and the pore wall may be 50 ⁇ m or less.
- the maximum distance between the surface of the inorganic fine powder and the pore wall can be determined by observing the cross section of the film or porous layer with an electron microscope and analyzing the cross-sectional image. Specifically, after embedding and solidifying the film with an epoxy resin, the film is cut, for example, in parallel to the thickness direction of the film (that is, perpendicular to the surface direction) using a microtome. After metallizing the cut surface, the image is enlarged and photographed at an arbitrary magnification (for example, 500 to 2000 times) that can be easily observed with a scanning electron microscope. The obtained image is taken into an image analyzer and subjected to image processing, and the maximum distance between the surface of the inorganic fine powder and the pore wall is determined.
- additives contained in the porous layer include a dispersant or a lubricant, a heat stabilizer, a light stabilizer, and an antistatic agent.
- the content of the additive in the porous layer may be 0.1 to 5 parts by mass with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. A porous layer having excellent stability over time can be obtained.
- the content of the dispersant or lubricant in the porous layer is 0.1 parts by mass or more with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. It is preferable. Thereby, the function of a dispersing agent or a lubricant is fully expressed.
- the content of the dispersant or the lubricant in the porous layer is preferably 4 parts by mass or less, and more preferably 2 parts by mass or less, with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. Thereby, a porous layer excellent in moldability, printability and the like can be obtained.
- Dispersants or lubricants include silane coupling agents; fatty acids having 8 to 24 carbon atoms such as oleic acid and stearic acid, and their metal salts, amides, esters with alcohols having 1 to 6 carbon atoms; poly (meth) acrylic 1 or more types selected from the group which consists of an acid and its metal salt etc. are mentioned.
- the content of the dispersant or lubricant in the porous layer is 0.001 part by mass or more with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. Is preferred. Thereby, the function of a heat stabilizer is fully expressed.
- the content of the dispersant or lubricant in the porous layer is preferably 1 part by mass or less and more preferably 0.5 parts by mass or less with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. preferable. Thereby, the porous layer excellent in economical efficiency is obtained.
- heat stabilizer which improves the external appearance of a thermoplastic resin film
- it is from the group which consists of heat stabilizers (it may be called antioxidant), such as a hindered phenol type, a phosphorus type, and an amine type. One or more selected may be mentioned.
- the content of the dispersant or lubricant in the porous layer is 0.001 part by mass or more with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. Is preferred. Thereby, the function of a photostabilizer fully develops.
- the content of the dispersant or lubricant in the porous layer is preferably 1 part by mass or less and more preferably 0.5 parts by mass or less with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder. preferable. Thereby, the porous layer excellent in economical efficiency is obtained.
- Examples of the light stabilizer that improves the appearance of the thermoplastic resin film include one or more selected from the group consisting of hindered amine-based, benzotriazole-based, and benzophenone-based light stabilizers.
- the light stabilizer may be used in combination with the above heat stabilizer.
- the adhesive layer is disposed on the surface in contact with the container body when the film is attached to the container body by in-mold molding.
- the surface of the adhesive layer is melted, and is integrated with the molten resin of the container body and cooled, whereby the film is attached to the plastic container.
- the adhesive layer is preferably made of a resin composition whose main component is a thermoplastic resin having a melting point lower than that of the thermoplastic resin contained in the porous layer.
- the difference between the melting point of the thermoplastic resin as the main component of the adhesive layer and the melting point of the resin composition contained in the porous layer is preferably 10 ° C. or higher, more preferably 15 ° C. or higher.
- the difference between the melting point of the thermoplastic resin as the main component of the adhesive layer and the melting point of the resin composition contained in the porous layer is preferably 150 ° C. or less. Thereby, blocking of the film in the previous stage of the film sticking process can be suppressed, and handling of the film becomes easy.
- Examples of the pre-stage of the film sticking process include a film storage stage and a film processing stage.
- the thermoplastic resin used in the adhesive layer includes ultra-low density, low density, or medium density high pressure polyethylene, linear linear low density polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, alkyl Ethylene / acrylic acid alkyl ester polymer having 1 to 8 carbon atoms, ethylene / methacrylic acid alkyl ester copolymer having 1 to 8 carbon atoms, and propylene represented by propylene / ⁇ -olefin copolymer 1 type or more selected from the group which consists of a resin, a polyester resin, a styrene elastomer resin, a polyamide resin, etc. is mentioned.
- the adhesive layer may contain linear low density polyethylene as a main component. Thereby, the contact bonding layer which is excellent in heat seal adhesive strength is obtained.
- the adhesive layer may contain other known additives for resin as long as the heat sealing property is not impaired.
- other additives for resin include inorganic pigments, dyes, nucleating agents, plasticizers, mold release agents, flame retardants, antioxidants, light stabilizers, and ultraviolet absorbers.
- the amount of other resin additive added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the entire adhesive layer. Thereby, the phenomenon which an additive accumulates on a die
- the method for producing a film having an adhesive layer is not particularly limited. For example, a method using a multilayer die system using a feed block, a multi-manifold, etc. at the time of extrusion molding; A method of extrusion laminating the adhesive layer; a combination of these methods and the like can be mentioned.
- An adhesive layer may be provided on the molded porous layer by a coating method.
- the adhesive layer is provided by a coating method
- the above-described material constituting the adhesive layer is dissolved in an organic solvent, applied to one surface of the porous layer, and then dried.
- an aqueous resin emulsion containing the above-mentioned material constituting the adhesive layer is applied to one surface of the porous layer.
- the above aqueous resin emulsion can be obtained by a method described in, for example, JP-A-58-118843, JP-A-56-2149, JP-A-56-106940, and JP-A-56-157445. It is done. Specifically, first, a material constituting the adhesive layer (sometimes referred to as an adhesive layer material) is supplied to a twin screw extruder and melt-kneaded. Thereafter, water containing the dispersion is introduced from a liquid introduction pipe provided in the compression section or vent area of the extruder, and the melted copolymer resin and water are kneaded by rotating the screw.
- a material constituting the adhesive layer (sometimes referred to as an adhesive layer material) is supplied to a twin screw extruder and melt-kneaded.
- water containing the dispersion is introduced from a liquid introduction pipe provided in the compression section or vent area of the extruder, and the melted copolymer resin and water are kneaded by rotating the screw
- the obtained kneaded material is reversed in phase in the housing of the extruder and discharged from the outlet nozzle of the extruder to the atmospheric pressure region, and water is further added as necessary, and the resultant mixture is accommodated in the storage tank.
- the average particle size of the adhesive layer material in the aqueous resin emulsion is preferably 0.01 to 3 ⁇ m, and more preferably 0.1 to 1 ⁇ m.
- the phase is stable in the state of the dispersion, and the storage property and coating property of the liquid are excellent.
- the adhesive layer formed by applying the dispersion liquid is more excellent in transparency after the obtained film is attached to the bottle by in-mold molding, that is, in the state of a resin molded product. Tend to be.
- a dispersant for example, various surfactants for dispersing the adhesive layer material may be added.
- the average particle size of the adhesive layer material in the aqueous resin emulsion is calculated by the following procedure. First, a sample solution (for example, an olefin resin emulsion solution) is dried under low temperature and reduced pressure conditions. The dried sample is enlarged to an appropriate magnification (for example, 1,000 times) using a scanning electron microscope, and a photographic image is taken. From the photographed image, an average value of 100 randomly selected particle diameters (major axis) existing in the sample is calculated. Thereby, an average particle diameter is calculated.
- a sample solution for example, an olefin resin emulsion solution
- an appropriate magnification for example, 1,000 times
- the solid content concentration of the adhesive layer material in the aqueous resin emulsion is preferably 8 to 60% by mass, and more preferably 20 to 50% by mass. When the solid content concentration is within the above range, the phase is stable in the state of the dispersion, and the storage and coating properties of the liquid are excellent.
- the surface layer may be porous or may not be porous.
- the surface layer is preferably porous. Thereby, the adhesiveness of a surface layer and printing ink improves.
- the resin constituting the surface layer may be the same as or different from the resin contained in the porous layer.
- the resin constituting the surface layer propylene resin, high density polyethylene, medium density polyethylene, linear linear low density polyethylene, ⁇ -olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer Polymer, ethylene / acrylic acid alkyl ester copolymer, ethylene / methacrylic acid alkyl ester copolymer (alkyl group having 1 to 8 carbon atoms), metal salt of ethylene / methacrylic acid copolymer, poly-4-methyl-1 -Polyolefin resins such as pentene and ethylene-cyclic olefin copolymers; Polyester resins such as polylactic acid, polyethylene terephthalate resin and polycarbonate resins; Polyvinyl chloride resins; Nylon-6, Nylon-6,6, Nylon-6 , 10, Nylon-6, 12, etc. polyamide resin; ABS
- the resin constituting the surface layer is preferably a thermoplastic resin having a melting point in the range of 105 to 280 ° C.
- the thermoplastic resin having a melting point in the range of 105 to 280 ° C. may be selected from propylene resin, high density polyethylene, polyethylene terephthalate resin, and the like.
- the thermoplastic resin having a melting point in the range of 105 to 280 ° C. may contain two or more kinds of resins.
- the resin constituting the surface layer may contain a propylene-based resin or high-density polyethylene as a main component. Thereby, a surface layer excellent in water resistance, chemical resistance, economic efficiency and the like can be obtained.
- the resin constituting the surface layer may be a highly polar resin such as a polyamide resin, an ionomer resin, polylactic acid, or a polycarbonate resin having a high affinity with the printing ink.
- the resin constituting the surface layer is made of a highly polar resin such as polyamide resin, ionomer resin, polylactic acid or polycarbonate resin, and a low polarity resin such as polypropylene resin, high density polyethylene or polyethylene terephthalate resin. May be included.
- the surface layer may contain an inorganic fine powder.
- the surface layer is an inorganic fine powder such as calcium carbonate, talc, titanium oxide, etc., and an inorganic fine powder having a volume average particle size of 0.1 to 3 ⁇ m is applied to the thermoplastic resin of the surface layer. 5 to 45% by mass is contained. Thereby, a surface layer suitable for printability can be obtained. In addition, at least one of the whiteness and opacity of the film can be improved.
- the surface layer is an inorganic fine powder such as calcium carbonate, silica, alumina, etc., and an inorganic fine powder having a volume average particle size of 3 to 10 ⁇ m is added to the surface layer thermoplastic resin in an amount of 0.
- the surface layer may contain an antistatic agent.
- antistatic agent examples include Pelestat (trade name) manufactured by Sanyo Kasei Kogyo Co., Ltd., and Elecon PE200 manufactured by Dainichi Seika Kogyo Co., Ltd.
- the content of the antistatic agent in the surface layer is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin in the surface layer.
- the content of the antistatic agent in the surface layer may be 0.1 parts by mass or more with respect to 100 parts by mass in total of the thermoplastic resin and the inorganic fine powder in the surface layer. Preferably, it is 0.5 parts by mass or more. Thereby, the antistatic property is sufficiently developed.
- the content of the antistatic agent in the surface layer is preferably 3 parts by mass or less and more preferably 2 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin in the surface layer.
- the content of the antistatic agent in the surface layer is preferably 3 parts by mass or less with respect to a total of 100 parts by mass of the thermoplastic resin and the inorganic fine powder in the surface layer, and 2 parts by mass. The following is more preferable. Thereby, the transfer defect of printing ink, the adhesion failure, the stain
- the surface layer may contain the same additive as the additive that can be added to the porous layer.
- the content of the additive in the surface layer may be in a range that does not hinder the properties required for the film, such as transparency, flexibility, and rigidity. For example, 0.01 to 3 relative to the thermoplastic resin in the surface layer. % By weight, preferably 0.01-2% by weight, more preferably 0.01-1% by weight.
- the method for producing the film having the surface layer is not particularly limited, and the film may be produced by the same method as that for the film having the adhesive layer.
- the film may be produced by extruding the surface layer from a die simultaneously with the molding of the porous layer, or may be produced by extrusion lamination of the surface layer on the porous layer using a plurality of dies.
- it may be produced by attaching a surface layer formed in a film shape to a porous layer.
- the surface coating layer is formed for the purpose of improving adhesion between the film and various functional material layers formed in the post-processing step. In another embodiment, the surface coating layer is formed for the purpose of increasing the adhesive strength between the container cheek and the film.
- the surface coating layer may include an adhesive material.
- the surface coating layer may contain an antistatic agent, an additive and the like.
- the adhesive material improves the adhesion between the surface coating layer and the film surface. It also mediates adhesion between the film surface and the printing ink or various functional material layers.
- the adhesive material include a water-soluble polymer and an aqueous dispersion polymer (sometimes referred to as an emulsion).
- the aqueous dispersion polymer include a vinyl resin emulsion or a polyurethane resin emulsion.
- the water-soluble polymer is dissolved in water in a coating agent containing a material constituting the surface coating layer (sometimes referred to as a surface coating layer material), and the coating agent is applied to the surface of the film. It preferably has a property of not being redissolved in water after drying.
- the material used for the adhesive layer is heated to melt or soften to develop tack, but the adhesive material in the surface coating layer preferably exhibits tack even at room temperature.
- water-soluble polymer examples include vinyl copolymers such as polyvinylpyrrolidone; partially saponified polyvinyl alcohol (sometimes referred to as PVA), fully saponified PVA, and salt of isobutylene-maleic anhydride copolymer (for example, Examples thereof include alkali metal salts, ammonium salts, etc.) vinyl copolymer hydrolysates; (meth) acrylic acid derivatives such as sodium poly (meth) acrylate and poly (meth) acrylamide; modified polyamides; Cellulose derivatives such as carboxymethyl cellulose and carboxyethyl cellulose; ring-opening polymerized polymers such as polyethyleneimine, polyethylene oxide and polyethylene glycol or modified products thereof; natural polymers such as gelatin and starch; or modified products thereof .
- vinyl copolymers such as polyvinylpyrrolidone; partially saponified polyvinyl alcohol (sometimes referred to as PVA), fully saponified PVA, and salt of isobuty
- the water-soluble polymer preferably contains 1 to 200 parts by mass of carbodiimides; diisocyanates; diglycidyl ethers and the like that can crosslink by reacting with the water-soluble polymer with respect to 100 parts by mass of the water-soluble polymer.
- Vinyl monomers constituting the vinyl copolymer include olefins; vinyl esters; unsaturated carboxylic acids and their alkali metal salts or acid anhydrides; alkyls having a branched or cyclic structure having up to 12 carbon atoms.
- said salt is an acid residue and a methyl sulfate ion and a chloride ion are preferable.
- the antistatic agent suppresses troubles caused by charging.
- the antistatic agent may be a copolymer having a quaternary ammonium salt structure in the molecule. Thereby, it is possible to prevent charging without impairing the adhesion between the surface coating layer and the ink or various functional material layers.
- the copolymer having a quaternary ammonium salt structure in the molecule has a monomer having a tertiary amine structure as an essential component, and after obtaining a copolymer with a monomer copolymerizable therewith, It can be obtained by quaternizing a tertiary amine with a quaternizing agent such as dimethyl sulfate, 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride.
- a quaternizing agent such as dimethyl sulfate, 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride.
- the copolymer having a quaternary ammonium salt structure in the molecule is obtained by grafting a monomer having a quaternary ammonium salt structure after obtaining the copolymer using only a monomer not containing nitrogen. It is obtained with.
- a copolymer having a quaternary ammonium salt structure in the molecule is soluble in water, dispersed in water, or dissolved in an organic solvent by balancing the amount of hydrophilic groups and hydrophobic groups in the quaternary ammonium salt structure and copolymer. Since both can be designed, the surface coating layer is appropriately selected according to the solvent of the paint for producing the surface coating layer.
- a monomer having a quaternary ammonium salt structure is used as a monomer constituting the vinyl resin emulsion or the polyurethane resin emulsion as the adhesive material, thereby having a quaternary ammonium salt structure in the molecule.
- a vinyl resin emulsion or a polyurethane resin emulsion may be obtained, and after obtaining an emulsion using a monomer having a tertiary amine structure, the above emulsion may be obtained by quaternization with a quaternizing agent. Good.
- the antistatic agent may be a cationic metal oxide sol.
- the cationic metal oxide sol may be an aluminum oxide sol or an alumina oxide-coated silica sol.
- sol-gel method a method in which an alkoxide such as aluminum isopropoxide is hydrolyzed with an acid
- gas a method in which aluminum chloride is introduced into a flame of hydrogen or the like
- the production method of the alumina oxide-coated silica sol includes a method in which an alkoxide such as tetraethoxysilane is hydrolyzed with an acid, a method in which silicon tetrachloride is introduced into a flame such as hydrogen, and a water glass ion-exchange resin. And a method of reacting aluminum chloride or aluminum acetylacetonate after obtaining a silica sol by a method such as desalting.
- the film of this embodiment can be manufactured using a well-known porous film manufacturing method.
- the film of this embodiment is preferably a film that is stretched in at least one axial direction.
- the film is preferably formed by an extrusion method.
- the method described below can also be applied when the film is composed of at least one porous layer, and can also be applied when the film has an adhesive layer, a surface layer, and the like in addition to the porous layer.
- the extrusion molding method examples include a sheet molding method, an inflation molding method, a calendar molding method, and rolling molding.
- the sheet molding method for example, the raw material of the film is melted and kneaded with an extruder set at a temperature higher than the melting point or glass transition point of the thermoplastic resin constituting the film, and formed into a sheet using a T die, I die, or the like.
- This is a method for producing a film-like resin molded product by cooling with extrusion, metal roll, rubber roll, metal belt or the like.
- the inflation molding method is, for example, by extruding a melt-kneaded raw material into a tube shape using a circular die, and cooling it with air, water, etc.
- the calendar molding method is a method of producing a film-shaped resin molded product by rolling a kneaded material with a plurality of hot rolls and processing it into a sheet shape, for example.
- the film is formed by a cast molding method.
- the cast molding method is, for example, supplying a thermoplastic resin composition constituting a film to an extruder and melting it, and using a T-die connected to the extruder to extrude it into a sheet and cool it against a cooling roll. This is a method for producing a film-like resin molded product.
- a film having a multilayer structure may be produced by a known method.
- Examples of the method for producing a film having a multilayer structure include a multilayer die method using a feed block, a multi-manifold, etc., an extrusion lamination method using a plurality of dies, and a combination thereof.
- one layer of the thermoplastic resin film is formed by a cast forming method. If necessary, the layer obtained by the cast molding method is stretched by utilizing the difference in peripheral speed of the roll, and then a laminate having a multilayer structure is formed by melt laminating the resin composition constituting the other layers of the film. Is obtained.
- the stretching method is not particularly limited, and various known methods can be used. Specifically, the stretching of each layer may be uniaxial stretching, biaxial stretching, or non-stretching.
- the direction of stretching may be the longitudinal direction or the lateral direction. Further, in the case of biaxial stretching, stretching may be performed simultaneously or sequentially.
- the stretching method when stretching a cast molded film, the longitudinal stretching method using the peripheral speed difference of the roll group, the transverse stretching method using a tenter oven, the rolling method, simultaneous biaxial by a combination of a tenter oven and a linear motor Examples thereof include a stretching method.
- stretching an inflation film the simultaneous biaxial stretching method by a tubular method is mentioned.
- the conditions for stretching the film including the porous layer are preferably low magnification. Thereby, fine voids are formed.
- the draw ratio is preferably about 1.2 to 8 times, more preferably 2 to 5 times.
- the draw ratio is preferably 1.5 to 12 times, more preferably 2 to 6 times in terms of area magnification. Thereby, it can suppress that a draw ratio is too low and a void
- the stretching temperature is set to a temperature range suitable for the thermoplastic resin contained in the porous layer.
- the stretching temperature is set to a temperature not lower than the glass transition temperature and not higher than the melting point of the crystal part.
- the stretching temperature is preferably 1 to 70 ° C. lower than the melting point.
- the stretching temperature is preferably 100 to 164 ° C.
- the stretching temperature is preferably 70 to 133 ° C.
- the stretching temperature is preferably a temperature at which crystallization does not proceed rapidly.
- the stretching speed is preferably 1 to 350 m / min, and more preferably 5 to 150 m / min.
- the temperature of the heat treatment is preferably not less than the stretching temperature and not more than 30 ° C. higher than the stretching temperature.
- the heat treatment may be performed using at least one of a roll and a heat oven.
- the heat treatment is preferably performed in a state where the stretched film is held under tension. Thereby, heat processing can be implemented effectively.
- oxidation treatment An oxidation treatment may be performed on the surface of the film.
- the surface of the film after molding has a relatively low surface free energy, is hydrophobic, and tends to repel ink and coating agents.
- the surface free energy of the surface of the film can be improved.
- adhesion between the printing ink and at least one of various functional material layers for example, a heat-sensitive color developing layer, an ink jet receiving layer, an adhesive layer, and a dry laminate layer formed in a post-processing step and the film. Will improve.
- an oxidation treatment may be performed. Specifically, when the film has an adhesive layer, an oxidation treatment is performed on the surface of the film where the adhesive layer of the porous layer is disposed. When the adhesive layer is disposed on the outermost surface of the film, the adhesive layer is subjected to an oxidation treatment. Further, when the film does not have an adhesive layer but has a surface layer, an oxidation treatment is performed on the surface of the film where the surface layer of the porous layer is not disposed. Thereby, the adhesive strength of a film and a container main body can be improved.
- Examples of the surface oxidation treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, and ozone treatment.
- As the surface oxidation treatment it is preferable to use a corona discharge treatment or a plasma treatment.
- the oxidation treatment amount is preferably 10 W ⁇ min / m 2 (600 J / m 2 ) or more, and preferably 20 W ⁇ min / m 2 (1,200 J / m 2 ) or more. More preferred. Thereby, a sufficient effect appears.
- the amount of oxidation treatment is preferably 200 W ⁇ min / m 2 (12,000 J / m 2 ) or less, and 180 W ⁇ min / m 2 (10,800 J / m 2 ) or less. It is more preferable. Thereby, the fall of the adhesiveness accompanying an excessive oxidation process can be suppressed.
- the coating process When an oxidation treatment is performed on the surface of the film, the surface free energy decreases with time, and the adhesion may decrease. Therefore, it is preferable to perform the coating process immediately after the surface oxidation treatment or within one week after the surface oxidation treatment to form the surface coating layer.
- the coating method include coating with a die coater, roll coater, gravure coater, spray coater, blade coater, reverse coater, air knife coater, size press coater, and the like.
- the coating process may be performed in combination with the film forming in the film forming line, and the coating process is performed on the film formed in the forming line in a line different from the film forming line. May be.
- the coating process may be performed before the stretching process, or the coating process may be performed after the stretching process.
- the surface coating layer may be formed by removing an excess solvent through a drying step using an oven or the like.
- the upper limit of the coating amount of the surface coating layer on the film is preferably 20 g / m 2 and more preferably 5 g / m 2 in terms of solid content after drying per unit area (square meter). It is preferably 1 g / m 2 .
- the lower limit of the coating amount is preferably 0.07 g / m 2 , more preferably 0.1 g / m 2 , and particularly preferably 0.15 g / m 2 .
- the coating amount of the surface coating layer is determined by the following procedure.
- the wet coating amount is calculated by subtracting the film mass before applying the coating agent from the wet film mass immediately after coating the coating agent on the film. Multiply the wet coating amount by the solid content concentration of the coating agent to determine the coating amount in terms of solid content.
- the coating amount after drying may be directly determined by peeling the surface coating layer from the film and measuring the mass of the peeled surface coating layer. Also, by observing a cross section parallel to the thickness direction of the film with a scanning electron microscope, the thickness of the surface coating layer is determined, and the thickness of the surface coating layer is multiplied by the density of the coating agent solid content. Thus, the coating amount after drying may be calculated.
- the surface coating layer may be formed on at least one surface of the film.
- the surface coating layer may be formed only on the surface on which information is printed or on the surface on which various functional materials are applied by post-processing.
- the surface coating layer may be formed only on the surface in contact with the molten resin when the film is attached to the container body by in-mold molding.
- embossing When the film of the present invention is attached to a plastic container by in-mold molding, the smoothness of the surface where the film and the plastic container are in contact is preferably lowered. Therefore, embossing can be performed.
- the embossing uses a rubber roll for the engraving metal roll. Embossing may be performed before stretching during film production, or may be performed after stretching.
- the embossed contact bonding layer can also be obtained by the method of sticking the film which embossed previously to the porous layer.
- the embossing pattern is preferably a pattern having continuous grooves obtained using an embossing roll engraved with discontinuous recesses, or a ridge line pattern obtained using an embossing roll having 50 to 300 grooves.
- the thickness D of the film is determined using a constant pressure thickness measuring instrument according to JIS K 7130: 1999 “Plastics—Film and Sheet—Thickness Measurement Method”.
- the thickness D of the film is preferably 20 ⁇ m or more, more preferably 40 ⁇ m or more, and further preferably 60 ⁇ m or more.
- the thickness D of the film is preferably 250 ⁇ m or less, and more preferably 200 ⁇ m or less.
- the density of the film is determined by an underwater substitution method using a film sample, based on the method A of JIS K 7112: 1999 “Plastics—Method of measuring density and specific gravity of non-foamed plastic”. If the film consists of only the porous layer, the density of the film is preferably 0.5 g / cm 3 or more, and more preferably 0.6 g / cm 3 or more. Thereby, the surface strength of the label can be maintained. The density of the film is preferably at 1.3 g / cm 3 or less, more preferably 1.0 g / cm 3 or less. Thereby, IML adhesiveness (heat seal strength) can be imparted to the film.
- the density of the film is preferably 0.6 g / cm 3 or more, and more preferably 0.7 g / cm 3 or more.
- the density of the film is preferably at 1.4 g / cm 3 or less, more preferably 1.1 g / cm 3 or less.
- Thermal resistance value Thermal resistance value of the film
- ISO 22007-3 thermal conductivity measuring apparatus (manufactured Ai Phase Ltd., apparatus name: ai-Phase Mobaile) according 2008 thermal conductivity of all layers of the measured film using a Using ⁇ and the total film thickness D, the following formula is used.
- R t d ⁇ 10 ⁇ 6 / ⁇
- R t is the thermal resistance value [m 2 ⁇ K / W] of the film
- D is the total film thickness [ ⁇ m]
- ⁇ the thermal conductivity of all the film layers [W / M ⁇ K].
- Thermal resistance R t of the film is preferably at 0.05m 2 ⁇ K / W or more, more preferably 0.1m 2 ⁇ K / W or more.
- Thermal resistance R t of the film is preferably from 0.25m 2 ⁇ K / W, more preferably not more than 0.20m 2 ⁇ K / W.
- To increase the thermal resistance R t of the film for example, to reduce the density of the porous, it is necessary or to increase the porosity or pore length of the porous layer.
- By setting the thermal resistance value Rt of the film within the above range it is possible to suppress a decrease in strength of the film and generation of orange peel.
- the thickness d of the porous layer in the film is determined by the following procedure. First, a cross section parallel to the thickness direction of the film is observed with a scanning electron microscope, and the ratio of the thickness of the porous layer to the film thickness D is determined by image analysis. Multiply the determined ratio by the film thickness D determined according to JIS K 7130: 1999 “Plastics-Film and Sheet-Thickness Measurement Method” to determine the thickness d of the porous layer.
- the ratio of the thickness of the porous layer to the film thickness is preferably 10% or more and 100% or less. Thereby, the porous layer excellent in heat insulation is obtained. In addition, a porous layer having a large whiteness or opacity can be obtained.
- the ratio is preferably 25% or more, more preferably 30% or more.
- the density ⁇ of the porous layer in the film is determined by an underwater substitution method based on the A method of JIS K 7112: 1999 “Plastics—Method for measuring density and specific gravity of non-foamed plastic”.
- the density ⁇ of the porous layer is determined by the following procedure. First, a film containing a porous layer is taken out from a labeled plastic container by cutting or the like. Next, the porous layer is peeled from the taken out film to obtain a sample for density measurement.
- the density ⁇ of the porous layer is determined by the following procedure. First, the cross section of the film taken out from the labeled plastic container is observed with a scanning electron microscope, and image analysis is performed to determine the thermoplastic resin, inorganic fine powder, and pores (portions of the porous layer) in the porous layer in the film. The volume ratio is determined. As the volume ratio, the area ratio of each part in the image may be substituted. Next, the density ⁇ of the porous layer is determined by adding the value obtained by multiplying the volume ratio of each part of the porous layer by the density of each part.
- the value obtained by multiplying the volume ratio of the thermoplastic resin by the density of the thermoplastic resin the value obtained by multiplying the volume ratio of the inorganic fine powder by the density of the inorganic fine powder, and the volume ratio of the pores multiplied by the density of air.
- the density ⁇ of the porous layer is determined by adding the values.
- the density of the porous layer of the film is preferably 0.5 g / cm 3 or more, and more preferably 0.6 g / cm 3 or more. Thereby, the surface strength of the label can be maintained. Moreover, generation
- the density of the porous layer of the film is preferably 1.3 g / cm 3 or less, and more preferably 1.0 g / cm 3 or less. Thereby, IML adhesiveness or heat seal strength can be imparted to the porous layer.
- the true density ⁇ 0 of the porous layer in the film is determined based on JIS K 7112: 1999 “Method for measuring density and specific gravity of non-foamed plastic” in JIS K 7112: 1999 using a sample obtained by thermally shrinking the porous layer peeled off from the film. Based on the law, it is determined by the underwater substitution method.
- the sample may be replaced with a newly prepared resin composition based on the composition.
- the true density ⁇ 0 of the porous layer is determined by the following procedure. First, the cross section of the film is observed with a scanning electron microscope, and by image analysis, for each part of the porous layer in the film other than the pores, the total volume of the portion other than the pores in the porous layer is 1 Determine the volume ratio. As the volume ratio, the area ratio of each part in the image may be substituted. Next, the true density ⁇ 0 of the porous layer is determined by adding the value obtained by multiplying the volume ratio of each part other than the pores in the porous layer by the density of each part.
- the ratio of the volume of each of the thermoplastic resin and the inorganic fine powder to the volume of the thermoplastic resin and the inorganic fine powder is determined.
- the true density ⁇ 0 of the porous layer is obtained. decide.
- the true density of the porous layer is preferably 1.0 g / cm 3 or more, and more preferably 1.2 g / cm 3 or more.
- the inorganic fine powder is presumed to function as a nuclei for pore generation, and the number of nuclei for pore generation increases as the content of the inorganic fine powder in the porous layer increases.
- the number of nuclei for generating pores increases, the number of pores after stretching also increases, and the heat insulating property of the porous layer is improved.
- in-mold adhesiveness is increased.
- the density of the porous layer decreases and a lightweight in-mold label can be obtained.
- the true density of the porous layer is preferably 1.9 g / cm 3 or less, and more preferably 1.8 g / cm 3 or less. If the pore diameter becomes excessively large, the pore wall may be easily buckled, but by adjusting the true density of the porous layer to the above range, the pore diameter in the porous layer after stretching is prepared. Can be adjusted to an appropriate range. Thereby, generation
- the porosity of the porous layer may be 15% or more, preferably 25% or more, and more preferably 35% or more. Thereby, the porous layer excellent in heat insulation is obtained. In addition, a porous layer having a large whiteness or opacity can be obtained.
- the porosity of the porous layer may be 75% or less, preferably 70% or less, and more preferably 65% or less. Thereby, generation
- the pore length L calculated by the following equation is used using the porosity and the thickness d of the porous layer.
- L d ⁇ ( ⁇ 0 ⁇ ) / ⁇ 0
- L is the pore length [ ⁇ m]
- ⁇ is the density [g / cm 3 ] of the porous layer
- ⁇ 0 is the true density [g / cm 3 ] of the porous layer.
- the pore length L is an index indicating the proportion of pores in the thickness d of the porous layer, and the longer the pore length L, the higher the heat insulation.
- the pore length L is preferably 20 ⁇ m or more.
- the thickness of the adhesive layer is determined by the same procedure as the thickness d of the porous layer. First, a cross section parallel to the thickness direction of the film is observed with a scanning electron microscope, and the ratio of the thickness of the adhesive layer to the film thickness D is determined by image analysis. The determined ratio is multiplied by the film thickness D determined in accordance with JIS K 7130: 1999 “Plastics-Film and Sheet-Thickness Measurement Method” to determine the thickness of the adhesive layer.
- the thickness of the adhesive layer is preferably 0.1 ⁇ m or more, and more preferably 0.5 ⁇ m or more. Thereby, sufficient adhesive force is obtained.
- the thickness of the adhesive layer is preferably 20 ⁇ m or less, and more preferably 10 ⁇ m or less. Thereby, when printing information on a film by offset printing, or when inserting a film in a metal mold
- the smoothness s of the surface of the film on the side where the adhesive layer of the porous layer is disposed is JIS P 8155: 2010 “Paper and paperboard—Smoothness test method” -Decided according to the "Oken method”.
- the smoothness s is preferably 5 to 4000 seconds.
- the smoothness s is more preferably 1000 seconds or less, and further preferably 500 seconds or less. Thereby, even when the size of the label is large, the air can be discharged sufficiently quickly.
- the smoothness s is more preferably 10 seconds or more, and further preferably 20 seconds or more. Thereby, it can suppress that molten resin is no longer filled into the adhesion side surface of a film at the time of in-mold shaping
- the surface wetting tension W obtained by the “test method” is preferably 34 mN / m or more, and more preferably 42 mN / m or more. Thereby, ink acceptability can fully be expressed.
- the surface wetting tension W is preferably 74 mN / m or less, and more preferably 72 mN / m or less. Thereby, it can suppress that the edge part of films sticks at the time of the punching process of a film.
- the wetting tension was measured by dripping the wetting tension test liquid mixture on the film and adding the liquid on the film as No. 1. Spread with a two-wire bar, and determine by the state of a droplet after 2 seconds.
- the surface resistivity R s at 23 ° C. and 50% RH is determined according to the surface resistivity of JIS K6911: 1995 “General Test Method for Thermosetting Plastics”.
- the surface resistivity of at least one surface of the film is preferably 1 ⁇ 10 8 to 1 ⁇ 10 12 ⁇ . Thereby, charging of the film can be prevented. When the surface resistivity is within the above range, a film excellent in antistatic properties and offset printing suitability can be obtained. At least one surface of the film may be a surface-treated surface.
- a charged label inserter is used when placing a film inside a mold.
- the charged label inserter uses a direct current high voltage generator to generate static electricity on the surface of the film that is in contact with the container body, and fixes the film to the mold by electrostatic adsorption.
- the surface resistivity of the surface of the film that is in contact with the container body is preferably 1 ⁇ 10 12 ⁇ or more.
- Information may be printed on the film.
- Information may be printed on the surface of the layer disposed on one side of the porous layer among the layers included in the film.
- Information may be printed on the surface of the layer disposed on the side of the porous layer where the adhesive layer is not disposed, among the layers included in the film.
- Information may be directly printed on the film by a printing method such as gravure printing, flexographic printing, letter press printing, screen printing, or electrophotographic recording method.
- a printing method such as an inkjet recording method, a thermal transfer recording method, or a pressure-sensitive transfer recording method
- a known receiving layer suitable for each printing method may be further provided on the surface of the film.
- the gravure printing, the ink jet recording method, and the electrophotographic recording method are excellent in definition. Letter press printing and flexographic printing can be applied to small lot printing.
- the ink used for printing may be an oil-based ink or an ultraviolet curable ink. From the viewpoint of scratch resistance, it is preferable to use an ultraviolet curable ink.
- the UV curable ink is dried and solidified by UV irradiation.
- the ultraviolet irradiation method is not particularly limited as long as the ultraviolet curable ink is cured.
- a metal halide lamp 200 to 400 nm
- a low pressure mercury lamp 180 to 250 nm
- a high pressure mercury lamp 250 to 365 nm
- a black light 350 ⁇ 360nm
- the ultraviolet rays irradiated from UV-LED lamp 355 ⁇ 375nm
- 300 ⁇ 3000mJ / cm 2 preferably include such be irradiated so that the irradiation dose of 400 ⁇ 1000mJ / cm 2 It is done.
- the thickness D of the entire film obtained in the sheet molding example is based on JIS K 7130: 1999 “Plastic-Film and Sheet-Thickness Measurement Method”, a constant pressure thickness measuring instrument (manufactured by Teclock Co., Ltd., device name: PG -01J). Moreover, the thickness of each layer in the film obtained in the sheet molding example was measured by the following procedure. First, the sample to be measured was cooled to a temperature of ⁇ 60 ° C. or lower with liquid nitrogen.
- the sample to be measured after cooling is placed on a glass plate, a razor blade (manufactured by Chic Japan Co., Ltd., trade name: Proline Blade) is applied to the sample to be measured at a right angle, and the sample to be measured is placed.
- a razor blade manufactured by Chic Japan Co., Ltd., trade name: Proline Blade
- the cross section of the sample for cross section measurement was observed using a scanning electron microscope (manufactured by JEOL Ltd., device name: JSM-6490), the boundary line was determined from the observed image, and the thickness of the entire film
- the ratio of the thickness of the layer to be measured to the thickness D was determined. Thereafter, the thickness of the layer to be measured was determined by multiplying the total thickness D by the above ratio determined by observing the sample for cross-sectional measurement.
- ⁇ Flexographic evaluation> The film obtained in each example and comparative example was subdivided with a width of 150 mm to prepare a slit-shaped sample.
- a flexographic printing machine (trade name “TCL”, manufactured by Taiyo Machinery Co., Ltd.) and an ultraviolet curable flexographic ink (trade name “UV flexo CF”, manufactured by T & K TOKA Corporation).
- Character information such as product name, manufacturer, sales company name, usage, precautions, etc., and a design including a barcode and design were printed.
- Printing was four-color printing. Printing was performed in an environment at a temperature of 23 ° C. and a relative humidity of 50%.
- the printing speed was 60 m / min.
- the printed sample is passed under an ultraviolet irradiator (metal halide lamp, 100 W / cm, 1 lamp, manufactured by Igraphic Co., Ltd.) at a speed of 60 m / min to dry the ink on the printed surface.
- an ultraviolet irradiator metal halide lamp, 100 W / cm, 1 lamp, manufactured by Igraphic Co., Ltd.
- the parison was expanded for 16 seconds, and the parison was brought into close contact with the mold to form a container, and the parison and the label were fused. Thereafter, the molded product was cooled in a mold and opened to obtain a plastic container with a label.
- the mold cooling temperature was 20 ° C.
- the shot cycle time was 34 seconds / time.
- Table 1 shows the materials used for film forming and their physical properties.
- the average particle size of the inorganic fine powder is a particle size obtained from the BET specific surface area
- D50 is a particle size at a cumulative value of 50% of the volume distribution by Microtrac HRA (made by Nikkiso Co., Ltd.).
- D90 indicates a particle size at a cumulative value of 90% (sometimes referred to as a volume average particle size).
- Table 2 shows the compositions of the films of Examples 1 to 12, production conditions, film characteristics, and evaluation results.
- Table 3 shows the compositions, production conditions, film characteristics and evaluation results of the films of Comparative Examples 1 to 5.
- the surface treatment was performed on the surface opposite to the adhesive layer. Further, the wetting tension and the surface resistivity were measured on the surface having no adhesive layer.
- “-” in flexo printability and offset printability indicates that evaluation was not performed.
- Example 1 (Film forming) As the material for the porous layer, high density polyethylene (A-1), heavy calcium carbonate (B-1) and additives (dispersant and antioxidant) described in Table 1 were used at a mass ratio of 30: 70: 1. After mixing and melt kneading with an extruder set at 180 ° C., the mixture was supplied to a T die set at 190 ° C. and extruded into a sheet. The extruded sheet was cooled to about 40 ° C. with a cooling roll to obtain a 296 ⁇ m unstretched sheet.
- A-1 high density polyethylene
- B-1 heavy calcium carbonate
- additives dispersant and antioxidant
- the non-stretched sheet was reheated to 110 ° C., it was stretched twice in the machine direction (MD stretching) using the peripheral speed difference of the roll group, and then reheated to 128 ° C. using a tenter oven. Thereafter, the film was stretched twice (TD stretching) in the transverse direction using a tenter. After that, annealing treatment is performed in a heat setting zone adjusted to 130 ° C., and it is cooled to about 60 ° C. with a cooling roll, and the ears are slit to obtain a biaxially stretched HDPE film composed of a single porous layer. It was.
- MD stretching machine direction
- TD stretching transverse direction
- annealing treatment is performed in a heat setting zone adjusted to 130 ° C., and it is cooled to about 60 ° C. with a cooling roll, and the ears are slit to obtain a biaxially stretched HDPE film composed of a single porous layer. It was.
- Exemplary film of Example 1 is the thickness D is 198Myuemu, thermal resistance R t is 0.21m 2 ⁇ K / W, the porous layer is the density ⁇ is 0.629 g / m 3, porosity p was 64%, the pore length L was 126 ⁇ m, the smoothness s was 111 seconds, and the surface resistance R s was 1.0 ⁇ 10 16 ⁇ .
- molding with the parison temperature 160 degreeC and 200 degreeC by the above-mentioned method was evaluated. 160 ° C. adhesiveness: ⁇ , 200 ° C. adhesiveness: ⁇ , orange peel: ⁇ .
- Example 2 to 3 Comparative Example 1: (Film forming) Films of Examples 2 to 3 and Comparative Example 1 were produced in the same manner as in Example 1 except that the MD stretching temperature and the TD stretching temperature were changed as shown in Table 2 or Table 3 in Example 1. In addition, it was judged that the film of Comparative Example 1 had remarkable stretching unevenness and could not withstand practical use. Therefore, the physical property value of the film is not measured for the film of Comparative Example 1. Also, IML aptitude, flexographic printing aptitude and offset printing aptitude are not evaluated. (In-mold molding evaluation) The obtained films of Examples 2 to 3 were evaluated for in-mold suitability (sometimes referred to as in-mold molding evaluation). In both cases, good results were obtained in both adhesiveness and orange peel as in Example 1.
- Example 4 Comparative Example 2: (Film forming) In Example 1, Example 4 and Comparative Example 2 were the same as Example 1 except that the take-up speed in the cooling roll was increased and the thickness of the unstretched sheet was changed as shown in Table 2 or Table 3. A film was prepared. (In-mold molding evaluation) The produced film was subjected to in-mold forming evaluation. The results are shown in Table 2 or Table 3. When the pore length was less than 20 ⁇ m, the heat insulation was insufficient and the suitability for IML was lowered.
- Examples 5-6 Film forming Films of Examples 5 to 6 were produced in the same manner as in Example 1 except that the thermoplastic resin of component A and the heavy calcium carbonate of component B were changed as shown in Table 2 in Example 1. (In-mold molding evaluation) The produced film was subjected to in-mold forming evaluation. The results are shown in Table 2. Although the composition of the porous layer was changed, an evaluation not inferior to Example 1 was obtained.
- Example 7 (Film forming) In Example 1, the amount of thermoplastic resin (A-1), heavy calcium carbonate (B-1), and additives (dispersant and antioxidant) in the porous layer was changed as shown in Table 2, The film of Example 7 was prepared by adjusting the thickness of the unstretched sheet and stretching conditions so that the porosity of the porous layer was 35 to 40%. (In-mold molding evaluation) The produced film was subjected to in-mold forming evaluation. The results are shown in Table 2. It can be seen that when the content of the inorganic fine powder in the porous layer is lowered, the suitability of IML is expressed if the pore length is secured by adjusting the stretching ratio or the like. However, an orange peel having an unevenness interval of less than 0.5 mm was generated.
- Comparative Example 3 (Film forming) As a material for the porous layer, high density polyethylene (A-1), heavy calcium carbonate (B-1) and additives (dispersant and antioxidant) described in Table 1 were used at a mass ratio of 75: 25: 1. It mixed and kneaded with the same direction biaxial kneader, and obtained the thermoplastic resin composition pellet for porous layers. On the other hand, high-density polyethylene (A-1), heavy calcium carbonate (B-1), and additives are mixed at a mass ratio of 80: 20: 0.5, and kneaded in a biaxial kneader in the same direction. A thermoplastic resin composition pellet was obtained.
- A-1 high density polyethylene
- B-1 heavy calcium carbonate
- additives dispersant and antioxidant
- thermoplastic resin composition pellets for the porous layer and the thermoplastic resin composition pellets for the surface layer were each melted in separate extruders. Both extruder temperatures were set at 180 ° C.
- the molten thermoplastic resin composition for the porous layer and the molten thermoplastic resin composition for the surface layer are supplied to one coextrusion die set at 190 ° C. Lamination was performed such that surface layer / porous layer / surface layer, and a two-kind three-layer unstretched sheet having a thickness of 574 ⁇ m was obtained.
- the non-stretched sheet is reheated to 110 ° C, then stretched twice in the longitudinal direction using the peripheral speed difference of the roll group, and subsequently reheated to 128 ° C using a tenter oven, and then the transverse direction using the tenter.
- the film was stretched twice. Thereafter, an annealing treatment was performed with a heat setting zone adjusted to 130 ° C., and cooling was performed to about 60 ° C. with a cooling roll, and the ear portion was slit to obtain a two-kind three-layer biaxially stretched HDPE film.
- Film of Comparative Example 3 is the thickness D is 60 [mu] m, the thermal resistance R t is 0.07m 2 ⁇ K / W, the porous layer has a thickness d of 49 .mu.m, the density ⁇ is 0.677 g / m 3 , the porosity p was 37%, the pore length L was 22 ⁇ m, the smoothness s was 109 seconds, and the surface resistance R s was 1.0 ⁇ 10 16 ⁇ .
- the produced film was subjected to in-mold forming evaluation. The results are shown in Table 3.
- a conventional in-mold film in which the content of the inorganic fine powder is less than 35% by mass is insufficient to increase the draw ratio in order to exhibit adhesiveness, and the interval between the irregularities is 0.5 mm or more. An orange peel occurred.
- Comparative Example 4 (Film forming) A two-type three-layer biaxially-stretched HDPE film of Comparative Example 4 was produced in the same manner as in Comparative Example 3 except that the thickness of the two-type three-layer unstretched sheet was 1248 ⁇ m.
- Film of Comparative Example 4 has a thickness D of 130 .mu.m, the thermal resistance R t is 0.12m 2 ⁇ K / W, the porous layer has a thickness d of 118 .mu.m, the density ⁇ is 0.677 g / m 3
- the porosity p was 39%, the pore length L was 51 ⁇ m, the smoothness s was 101 seconds, and the surface resistance R s was 1.1 ⁇ 10 16 ⁇ .
- Comparative Example 5 (Film forming) In Example 1, the blending amount of the thermoplastic resin (A-1), heavy calcium carbonate (B-1) and additives (dispersant and antioxidant) in the porous layer was changed to 20: 80: 1. An attempt was made to produce a film. However, there are few thermoplastic resins used as a dispersion medium, and an unstretched sheet formed with a T-die becomes brittle and cannot be longitudinally stretched. Therefore, the physical property value of the film is not measured for the film of Comparative Example 5. Also, IML aptitude, flexographic printing aptitude and offset printing aptitude are not evaluated.
- Example 8 (Film forming) As the material for the porous layer, high density polyethylene (A-1), heavy calcium carbonate (B-1) and additives (dispersant and antioxidant) described in Table 1 were used at a mass ratio of 30: 70: 1. It mixed and kneaded with the same direction biaxial kneader, and obtained the thermoplastic resin composition pellet for porous layers. On the other hand, high-density polyethylene (A-1), heavy calcium carbonate (B-1), and additives are mixed at a mass ratio of 80: 20: 0.5, and kneaded in a biaxial kneader in the same direction. A thermoplastic resin composition pellet was obtained.
- A-1 high density polyethylene
- B-1 heavy calcium carbonate
- additives dispersant and antioxidant
- thermoplastic resin composition pellets for the porous layer the thermoplastic resin composition pellets for the surface layer, and the ethylene- ⁇ olefin copolymer (Nippon Polyethylene Co., Ltd.), which is the resin that becomes the adhesive layer Made by Kernel KF270 (trade name), melting point: 100 ° C.) were melted in separate extruders. The temperatures of the extruders were all set at 180 ° C.
- a molten thermoplastic resin composition for a porous layer, a molten thermoplastic resin composition for a surface layer, and a molten ethylene- ⁇ -olefin copolymer were set at 190 ° C.
- the non-stretched sheet After reheating the non-stretched sheet to 129 ° C, it is stretched twice in the longitudinal direction using the difference in peripheral speed of the roll group, and then reheated to 135 ° C using a tenter oven, and then transversely using the tenter. The film was stretched twice. Thereafter, an annealing treatment was performed in a heat setting zone adjusted to 130 ° C., and cooling was performed to about 60 ° C. with a cooling roll, and the ear portion was slit to obtain a three-layer triaxially stretched HDPE film.
- the film of Example 8 was peeled off by hand and the porous layer could be taken out.
- the thickness D of the entire film is 67 .mu.m
- the thermal resistance R t is 0.02m 2 ⁇ K / W
- porous layer density ⁇ is 1.060 g / m 3
- porosity p is 40
- the hole length L was 22 ⁇ m
- the smoothness s was 1284 seconds
- the surface resistance R s was 9.7 ⁇ 10 15 ⁇ .
- Example 8 The film of Example 8 was embedded with an epoxy resin and cut with a microtome to prepare a sample for cross-sectional measurement. Next, a cross section of the sample was observed using a scanning electron microscope (manufactured by JEOL Ltd., device name: JSM-6490), and the boundary line was determined from the observed image. The ratio of the thickness d of the porous layer to the thickness D of the entire film was 42%. From the above ratio, the thickness d of the porous layer was determined to be 55 ⁇ m.
- the volume ratio of each component was determined from the observed image.
- the volume ratio of component (A-1) was 58% by volume, and the volume ratio of component (B-1) was 42% by volume.
- the density of component (A-1) was 0.896 g / cm 3
- the density of component (B-1) was 2.890 g / cm 3 .
- the content of component (A-1) was 29.98% by mass.
- the content of component (B-1) was 70.02% by mass. This agreed well with the mixing ratio of the raw materials of the porous layer.
- Examples 9-11 (Film forming) As the material for the porous layer, high density polyethylene (A-1), heavy calcium carbonate (B-1) and additives (dispersant and antioxidant) described in Table 1 were used at a mass ratio of 30: 70: 1. It mixed and kneaded with the same direction biaxial kneader, and obtained the thermoplastic resin composition pellet for porous layers. On the other hand, high density polyethylene (A-1), heavy calcium carbonate (B-1) and additives are mixed at a mass ratio of 80: 20: 0.5, and kneaded in the same kneader to heat the surface layer. A plastic resin composition pellet was obtained.
- thermoplastic resin composition pellets for the porous layer and the thermoplastic resin composition pellets for the surface layer were each melted in separate extruders. Both extruder temperatures were set at 180 ° C.
- the molten thermoplastic resin composition for the porous layer and the molten thermoplastic resin composition for the surface layer are supplied to one coextrusion die set at 190 ° C. Layered / porous layer / surface layer were laminated and extruded into a sheet. The obtained sheet was cooled to about 40 ° C. with a cooling roll to obtain a 305 ⁇ m unstretched sheet.
- the non-stretched sheet is reheated to 110 ° C, then stretched twice in the longitudinal direction using the peripheral speed difference of the roll group, and subsequently reheated to 128 ° C using a tenter oven, and then the transverse direction using the tenter.
- the film was stretched twice. Thereafter, an annealing treatment was performed with a heat setting zone adjusted to 130 ° C., and cooling was performed to about 60 ° C. with a cooling roll, and the ear portion was slit to obtain a two-kind three-layer biaxially stretched HDPE film.
- the two-type three-layer biaxially stretched HDPE film of Example 9 could be peeled off by hand and the porous layer taken out.
- the thickness D of the entire film is 211Myuemu
- thermal resistance R t is 0.22m 2 ⁇ K / W
- the porous layer has a thickness d 202 ⁇ m
- density ⁇ is 0.607 g / m 3
- the porosity P was 65%
- the pore length L was 137 ⁇ m.
- the surface wetting tension W was 31 mN / m.
- A-1) N, N′-dimethylaminoethylmethacrylamide (manufactured by Kojin Co., Ltd.): 40% by mass (A-2) n-butyl acrylate (manufactured by Kanto Chemical Co., Inc.): 35% by mass (A-3) Octadecyl acrylate (manufactured by Kanto Chemical Co., Inc.): 25% by mass (B) Polyethyleneimine (Nippon Shokubai Co., Ltd., Epomin-1000 (trade name)) (C) Epichlorohydrin adduct of water-soluble polyamine polyamide (manufactured by Seiko PMC Co., Ltd., WS-4024 (trade name))
- Example 12 (Film forming) In Example 1, the film of Example 12 was obtained in the same manner as Example 1 except that the additive composition of the porous layer layer composition was changed to 6 parts by mass. White powder was seen on the film surface.
- In-mold molding evaluation The obtained film was evaluated for in-mold molding. The results are shown in Table 2. The in-mold suitability was the same as in Example 2.
- (Flexo printing evaluation) One side of the obtained film was subjected to corona discharge treatment at an intensity of 45 W / m 2 / min, and flexographic printing evaluation was performed on the corona discharge treatment side, but ink transferability and ink adhesion were poor. No offset printing evaluation was performed.
- the adhesive layer is adjusted by adjusting the melting point of the thermoplastic resin contained in the outermost surface of the plastic container and the melting point of the thermoplastic resin contained in the layer in contact with the plastic container of the film to satisfy a specific relationship. Even if it was not provided, a labeled plastic container excellent in the adhesiveness of the label was obtained. Moreover, when the wetting tension was increased by corona discharge, printability could be imparted, and by providing an appropriate surface coating layer, a film having excellent surface antistatic properties and good printability could be obtained.
- a film having a high porosity, a small pore size and a uniform film is obtained, so that a high adhesive force is exhibited even under a low parison temperature at the time of in-mold molding, and at the same time, the occurrence of orange peel is extremely high.
- a few labeled plastic containers were obtained. Therefore, it is suitable for the manufacture of a plastic container with a label formed by sticking a thermoplastic resin film. Further, printability can be imparted by appropriate surface treatment, and handling defects due to static electricity can be suppressed when the film is processed. Therefore, it is also suitable for uses such as printing paper and labels.
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Abstract
Description
[先行技術文献]
[特許文献]
[特許文献1]米国特許第4,837,075号明細書
[特許文献2]実開平1-105960号公報
[特許文献3]特開平9-207166号公報
[特許文献4]特開2000-290411号公報
(A)前記多孔質層は、熱可塑性樹脂25~65質量部と、無機微細粉末35~75質量部とを含む。
(B)次式(1)で表される多孔質層の空孔長Lが、20μm以上である。
L=d×(ρ0-ρ)/ρ0 ・・・式(1)
式(1)において、Lは空孔長[μm]であり、dは、多孔質層の厚さ[μm]であり、ρは、多孔質層の密度[g/cm3]であり、ρ0は、多孔質層の真密度[g/cm3]である。
(C)前記多孔質層の厚さdは、前記フィルムの厚さDの10~100%である。
p=(ρ0-ρ)/ρ0 ×100・・・式(2)
式(2)において、pは多孔質の空孔率[%]であり、ρは、多孔質層の密度[g/cm3]であり、ρ0は、多孔質層の真密度[g/cm3]である。
Rt=D×10-6/λ・・・式(3)
式(3)において、Rtはフィルムの熱抵抗値[m2・K/W]であり、Dはフィルムの厚さ[μm]であり、λはフィルムの熱伝導率[W/m・K]である。
Tf-10≦Tv≦Tf+60 ・・・式(4)
式(4)において、Tvは、ラベル付きプラスチック容器の容器本体の最表面に含まれる熱可塑性樹脂の融点であり、Tfは、フィルムの容器本体に接する層に含まれる熱可塑性樹脂の融点である。
p=(ρ0-ρ)/ρ0 ×100・・・式(2)
式(2)において、pは前記多孔質の空孔率[%]であり、ρは、前記多孔質層の密度[g/cm3]であり、ρ0は、前記多孔質層の真密度[g/cm3]である。
Rt=D×10-6/λ・・・式(3)
前記式(3)において、Rtは前記フィルムの熱抵抗値[m2・K/W]であり、Dは前記フィルムの厚さ[μm]であり、λは前記フィルムの熱伝導率[W/m・K]である。
本実施形態において、ラベル付きプラスチック容器は、容器本体と、ラベルとを有する。ラベルは、例えば、容器本体にフィルムを貼着することで形成される。
本実施形態のラベル付きプラスチック容器は、例えば、インモールド成形法により作製される。より具体的には、金型の内側の面にフィルム(インモールドラベルと称する場合がある。)を配置した後、当該金型内に成形可能な状態の熱可塑性樹脂組成物を注入することで作製される。インモールド成形法としては、ブロー成形法、インジェクション成形法などを例示することができる。
容器本体の材料は、特に限定されず、公知の材料を使用することができる。容器本体の成形方法は、特に限定されず、公知の成形法を使用することができる。
(容器材料)
容器本体の材料は、中空容器が成形可能な材料であってよい。容器本体の材料としては、例えば、熱可塑性樹脂が使用される。熱可塑性樹脂としては、ポリエチレンテレフタレート(PET)又はその共重合体、ポリカーボネート樹脂などのポリエステル系樹脂;ポリプロピレン(PP)、ポリエチレン(PE)などのポリオレフィン系樹脂等を挙げることができる。ブロー成形法によりラベル付きプラスチック容器を作製する場合、好ましくはポリオレフィン系樹脂が使用される。容器本体の材料として、上記の熱可塑性樹脂を主成分とする熱可塑性樹脂組成物が使用されてもよい。
Tf-10≦Tv≦Tf+60
ここで、Tvは、プラスチック容器の容器本体の表面に含まれる熱可塑性樹脂の融点である。Tfは、フィルムの容器本体に接する側の表面に含まれる熱可塑性樹脂の融点である。特に、Tfが、後述する多孔質層に含まれる熱可塑性樹脂の融点である場合には、インモールドラベルが、多孔質層の容器本体側の面に接着層を有しない場合であっても、ブリスター及びオレンジピールを抑制することができる。
本実施形態において、フィルムは、少なくとも1層の多孔質層を有する。フィルムは、多孔質層の一方の面の側に配される表面層をさらに有してもよい。フィルムは、多孔質層の一方の面の側に配される表面塗工層をさらに有してもよい。フィルムは、多孔質層の一方の面の側に配される接着層をさらに有してもよい。フィルムが接着層を有する場合、表面層及び表面塗工層の少なくとも一方は、多孔質層の接着層が配されていない面の側に配されてよい。接着層は、前記多孔質層の一方の面に接して配されてよい。表面層又は表面塗工層は、前記多孔質層の他方の面に接して配されてよい。
[多孔質層]
本実施形態において、多孔質層は、熱可塑性樹脂と無機微細粉末とを含む。多孔質層は、添加剤を含んでもよい。
(熱可塑性樹脂)
多孔質層に含まれる熱可塑性樹脂は、フィルム状に成形することができる材料であれば、その種類は特に制限されない。多孔質層に含まれる熱可塑性樹脂としては、高密度ポリエチレン、中密度ポリエチレン、低密度ポリエチレン、ポリプロピレン、プロピレン系共重合樹脂、ポリメチル-1-ペンテン、エチレン・環状オレフィン共重合体等のオレフィン系樹脂;エチレン・酢酸ビニル共重合体、エチレン・アクリル酸共重合体、マレイン酸変性ポリエチレン、マレイン酸変性ポリプロピレン等の官能基含有ポリオレフィン樹脂;アタクティックポリスチレン、シンジオタクティックポリスチレン、スチレン-マレイン酸共重合体等のスチレン系樹脂;ポリエチレンテレフタレート、ポリエチレンテレフタレートイソフタレート、ポリブチレンテレフタレート、ポリブチレンサクシネート、ポリブチレンアジペート、ポリ乳酸、ポリカーボネート等のエステル系樹脂;ナイロン-6、ナイロン-6,6等のアミド系樹脂;これらの樹脂の2種類以上の混合物などが挙げられる。
多孔質層に含まれる無機微細粉末としては、炭酸カルシウム、焼成クレイ、シリカ、けいそう土、白土、タルク、酸化チタン、硫酸バリウム、アルミナ、ゼオライト、マイカ、セリサイト、ベントナイト、セピオライト、バーミキュライト、ドロマイト、ワラストナイト、水酸化アルミニウム、ガラスファイバー等からなる群から選択される1種以上が挙げられる。多孔質層が、炭酸カルシウム、タルク及び酸化チタンの少なくとも1種を含む場合、不透明度又は白色度の大きな多孔質層が得られる。また、多孔質層の成形性が向上する。炭酸カルシウム及び酸化チタンの少なくとも1種を含むことにより、当該効果の更に優れた多孔質層が得られる。
多孔質層に含まれる添加剤としては、分散剤又は滑剤、熱安定剤、光安定剤、帯電防止剤、等が挙げられる。多孔質層における添加剤の含有量は、熱可塑性樹脂及び無機微細粉末の合計100質量部に対して、0.1~5質量部であってよい。経時安定性に優れた多孔質層が得られる。
本実施形態において、接着層は、インモールド成形によりフィルムを容器本体に貼着するときに、容器本体と接する側の面に配される。インモールド成形によりフィルムを容器本体に貼着するときに、接着層の表面が溶融し、容器本体の溶融樹脂と一体化して冷却されることにより、フィルムがプラスチック容器に貼着する。
表面層は多孔質であってもよく、多孔質でなくてもよい。表面層に印刷情報を付加する場合には、表面層は多孔質であることが好ましい。これにより、表面層と印刷用インキとの密着性が向上する。
一実施形態において、表面塗工層は、印刷インキ又は後加工工程で形成する各種機能材層と、フィルムとの密着性を高める目的で形成される。他の実施形態において、表面塗工層は、容器頬態と、フィルムとの接着強度を高める目的で形成される。表面塗工層は、接着性材料を含んでよい。表面塗工層は、帯電防止剤、添加剤などを含んでもよい。
接着性材料は、表面塗工層とフィルム表面との接着性を向上させる。また、フィルム表面と、印刷用インキ又は各種機能材層との接着の仲介をする。接着性材料としては、水溶性ポリマー、水性分散体ポリマー(エマルジョンと称される場合がある。)等が挙げられる。水性分散体ポリマーとしては、ビニル系樹脂エマルジョン又はポリウレタン樹脂エマルジョンを挙げることができる。
帯電防止剤は、帯電によるトラブルを抑制する。帯電防止剤は、分子内に4級アンモニウム塩構造を有する共重合体であってよい。これにより、表面塗工層と、インキ又は各種機能材層との接着性を阻害することなく、帯電を防止することができる。一実施形態において、分子内に4級アンモニウム塩構造を有する共重合体は、3級アミン構造を有するモノマーを必須成分として、これと共重合可能なモノマーとの共重合体を得た後、当該3級アミンをジメチル硫酸、3-クロロ-2-ヒドロキシプロピルトリメチルアンモニウムクロリド、グリシジルトリメチルアンモニウムクロリド等の4級化剤で4級化することで得られる。
本実施形態のフィルムは、公知の多孔質フィルム製造法を用いて製造することができる。本実施形態のフィルムは、少なくとも1軸方向に延伸されてなるフィルムであることが好ましい。
フィルムの成形は押し出し成形法によることが好ましい。なお、下記に説明する方法は、フィルムが少なくとも1層の多孔質層からなる場合にも適用でき、フィルムが多孔質層に加えて、接着層、表面層などを有する場合にも適用できる。
フィルムを構成するいずれかの層を延伸する場合において、延伸方法は特に限定されず、公知の種々の方法を使用することができる。具体的には、各層の延伸は1軸延伸であってもよく、2軸延伸であってもよく、無延伸であってもよい。また、延伸の方向は縦方向でも、横方向でもよい。さらに、2軸延伸の場合は、同時に延伸してもよく、逐次延伸してもよい。
(酸化処理)
フィルムの表面に、酸化処理が施されてもよい。成形後のフィルムの表面は、表面自由エネルギーが比較的低く、疎水性でインクや塗工剤をはじきやすい傾向にある。フィルムの表面に酸化処理を施すことにより、フィルムの表面の表面自由エネルギーを向上させることができる。その結果、印刷インキ、及び、後加工工程で形成する各種機能材層(例えば、感熱発色層、インクジェット受容層、接着剤層、ドライラミネート層である。)の少なくとも一方と、フィルムとの密着性が向上する。
フィルムの表面に酸化処理を施した場合、経時的に表面自由エネルギーが低下し、密着性が低下する場合がある。そこで、表面酸化処理の直後、又は表面酸化処理から1週間以内に、塗工工程を実施して、表面塗工層を形成することが好ましい。塗工方法としては、ダイコーター、ロールコーター、グラビアコーター、スプレーコーター、ブレードコーター、リバースコーター、エアーナイフコーター、サイズプレスコーター等による塗工、浸漬等が挙げられる。
本発明のフィルムをインモールド成形によりプラスチック容器に貼着する際、フィルムとプラスチック容器とが接触する面は平滑度を下げておくことが好ましい。そのためにエンボス加工を行うことができる。エンボス加工は彫刻金属ロールと対するゴムロールを用いる。エンボス加工は、フィルム製造時の延伸前に行ってもよく、延伸後に行ってもよい。また、予めエンボス加工を行ったフィルムを多孔質層に貼合する方法で、エンボス加工された接着層を得ることもできる。
エンボス加工のパターンは、不連続の凹部を彫刻したエンボスロールを用いて得られる連続した溝を有するパターンや、50~300線の溝を有するエンボスロールで得られる稜線パターンが好ましい。
[フィルム全層の特性]
(厚さ)
フィルムの厚さDは、JIS K 7130:1999「プラスチック-フィルム及びシート-厚さ測定方法」に従い、定圧厚さ測定器を用いて決定される。フィルムの厚さDは、20μm以上であることが好ましく、40μm以上であることがより好ましく、60μm以上であることがさらに好ましい。これにより、インモールド成形によりフィルムを容器本体に貼着する場合において、ラベルインサーターを用いて金型の内側にフィルムを挿入する場合に、適切な位置にフィルムを配置することが容易になる。また、フィルムのシワの発生を抑制することができる。
フィルムの密度は、フィルム試料を用いて、JIS K 7112:1999「プラスチック-非発泡プラスチックの密度及び比重の測定方法」のA法に基づき、水中置換法によって決定される。フィルムが多孔質層のみからなる場合、フィルムの密度は、0.5g/cm3以上であることが好ましく、0.6g/cm3以上であることがより好ましい。これにより、ラベルの表面強度を維持することができる。また、フィルムの密度は、1.3g/cm3以下であることが好ましく、1.0g/cm3以下であることがより好ましい。これにより、フィルムにIML接着性(ヒートシール強度)を付与することができる。
フィルムの熱抵抗値Rtは、ISO 22007-3:2008に従って熱伝導率測定機(株式会社アイフェイズ製、機器名:ai-Phase Mobaile)を用いて測定されるフィルムの全層の熱伝導率λと、フィルム全層厚さDとを用いて、下記の式により算出する。
Rt=d×10-6/λ
ここで、Rtは、フィルムの熱抵抗値[m2・K/W]であり、Dは、フィルムの全層厚さ[μm]であり、λ:フィルムの全層の熱伝導率[W/m・K]である。
(厚さ)
フィルムにおける多孔質層の厚さdは、下記の手順で決定する。まず、フィルムの厚さ方向に平行な断面を走査型電子顕微鏡で観察して、画像解析により、フィルム厚さDに占める多孔質層の厚さの割合を決定する。決定された割合に、JIS K 7130:1999「プラスチック-フィルム及びシート-厚さ測定方法」に従って決定されたフィルムの厚さDを乗じて、多孔質層の厚さdを決定する。
フィルムにおける多孔質層の密度ρは、JIS K 7112:1999「プラスチック-非発泡プラスチックの密度及び比重の測定方法」のA法に基づき、水中置換法によって決定する。なお、ラベル付きプラスチック容器に貼着されたフィルムを試料として、当該フィルムに含まれる多孔質層の密度ρを決定する場合、当該多孔質層の密度ρは、下記の手順により決定する。まず、切断などにより、ラベル付きプラスチック容器から多孔質層を含むフィルムを取り出す。次に、取り出されたフィルムから多孔質層を剥離して、密度測定用の試料を得る。次に、JIS K 7112:1999「プラスチック-非発泡プラスチックの密度及び比重の測定方法」のA法に基づき、水中置換法によって、上記の密度測定用の試料の密度を測定することにより、多孔質層の密度ρを決定する。
フィルムにおける多孔質層の真密度ρ0は、フィルムから剥離した多孔質層を熱収縮させたものを試料として、JIS K 7112:1999「プラスチック-非発泡プラスチックの密度及び比重の測定方法」のA法に基づき、水中置換法によって決定する。なお、多孔質層に使用されている熱可塑性樹脂組成物の組成が判明している場合には、当該組成に基づいて、新たに作製した樹脂組成物をもって、上記試料に替えてもよい。
多孔質層の空孔率p[%]は、上記測定によって得られた密度ρと、上記測定によって得られた真密度ρ0とを用いて、下記の式により算出する。
P=(ρ0-ρ)/ρ0 ×100
多孔質層の空孔の量を示す指標として、上記の空孔率と、上記の多孔質層の厚さdとを用いて、下記の式により算出される空孔長Lを用いる。
L=d×(ρ0-ρ)/ρ0
ここで、Lは空孔長[μm]であり、ρは多孔質層の密度[g/cm3]であり、ρ0は多孔質層の真密度[g/cm3]である。
(厚さ)
接着層の厚さは、多孔質層の厚さdと同様の手順により決定される。まず、フィルムの厚さ方向に平行な断面を走査型電子顕微鏡で観察して、画像解析によりフィルム厚さDに占める接着層の厚さの割合を決定する。決定された割合に、JIS K 7130:1999「プラスチック-フィルム及びシート-厚さ測定方法」に従って決定されたフィルムの厚さDを乗じて、接着層の厚さを決定する。
(平滑度)
フィルムの表面のうち、多孔質層の接着層が配された側の表面(接着側表面と称する場合がある。)における平滑度sは、JIS P 8155:2010「紙及び板紙-平滑度試験方法-王研法」に従って決定される。平滑度sは、5~4000秒であることが好ましい。これにより、インモールド成形によりフィルムを容器本体に貼着する場合において、フィルムと容器本体の間の空気が速やかに排出され、空気溜りのないラベル付きプラスチック容器が得られる。
フィルムの表面に枚葉オフセット印刷、輪転オフセット印刷、グラビア印刷、フレキソ印刷、レタープレス印刷、スクリーン印刷等の各種印刷方式で印刷を施す場合、JIS K 6768:1999「プラスチック-フィルム及びシート-ぬれ張力試験方法」で求められる表面のぬれ張力Wは、34mN/m以上であることが好ましく、42mN/m以上であることがより好ましい。これにより、インキ受理性を十分に発現することができる。表面のぬれ張力Wは74mN/m以下であることが好ましく、72mN/m以下であることがより好ましい。これにより、フィルムの打抜き加工時に、フィルム同士の端部が貼り付くことを抑制できる。なお、ぬれ張力の測定は、フィルムにぬれ張力試験用混合液を滴下し、フィルム上の液をNo.2ワイヤーバーで広げ、2秒後の液滴の状態で判定する。
23℃50%RHにおける表面抵抗率Rsは、JIS K6911:1995「熱硬化性プラスチック一般試験方法」の表面抵抗率に従って決定する。フィルムの少なくとも一方の表面の表面抵抗率は、1×108~1×1012Ωであることが好ましい。これにより、フィルムの帯電を防止することができる。表面抵抗率が上記の範囲内である場合、帯電防止性及びオフセット印刷適性に優れたフィルムが得られる。フィルムの少なくとも一方の表面は、表面加工を施された面であってよい。
[印刷]
フィルムには、情報が印刷されてよい。フィルムに含まれる層のうち、多孔質層の一方の面の側に配される層の表面に、情報が印刷されてよい。フィルムに含まれる層のうち、多孔質層の接着層が配されていない側に配される層の表面に、情報が印刷されてもよい。グラビア印刷、フレキソ印刷、レタープレス印刷、スクリーン印刷、電子写真記録方式等の印刷方式により、フィルムに情報が直接印刷されてもよい。インクジェット記録方式、熱転写記録方式、感圧転写記録方式等の印刷方式を用いる場合には、フィルムの表面に、それぞれの印刷方式に適した公知の受容層をさらに設けてよい。グラビア印刷、インクジェット記録方式及び電子写真記録方式は、精細性に優れる。レタープレス印刷及びフレキソ印刷は、小ロットの印刷にも対応できる。
<厚さ>
シート成形例で得られたフィルム全体の厚さDは、JIS K 7130:1999「プラスチック-フィルム及びシート-厚さ測定方法」に基づき、定圧厚さ測定器(株式会社テクロック製、機器名:PG-01J)を用いて測定した。また、シート成形例で得られたフィルムにおける各層の厚さは、下記の手順で測定した。まず、測定対象試料を液体窒素にて-60℃以下の温度に冷却した。次に、冷却後の測定対象試料をガラス板上に載置し、測定対象試料に対してカミソリ刃(シック・ジャパン株式会社製、商品名:プロラインブレード)を直角に当てて、測定対象試料を切断することで、断面測定用の試料を作製した。次に、断面測定用の試料を走査型電子顕微鏡(日本電子株式会社製、機器名:JSM-6490)を使用して断面を観察し、観察像から境界線を判別して、フィルム全体の厚さDに対する、測定対象となる層の厚さの比率を決定した。その後、全体の厚さDに、断面測定用の試料の観察により決定された上記の比率を乗算することで、測定対象となる層の厚さを決定した。
各実施例、比較例で得られたフィルムを150mm幅で小割して、スリット状の試料を作製した。スリット状の試料の一方の表面に、フレキソ印刷機(商品名「TCL」、太陽機械製作所株式会社社製)、及び紫外線硬化型フレキソインキ(商品名「UVフレキソCF」、T&K TOKA株式会社製)を用いて、商品名、製造元、販売会社名、使用方法、注意事項等の文字情報と、バーコード及び意匠を含む図柄とを印刷した。印刷は、4色印刷であった。印刷は、温度23℃、相対湿度50%の環境下で実施した。また、印刷速度は、60m/分であった。次に、印刷後の試料を、紫外線照射器(メタルハライド灯、100W/cm、1灯、アイグラフィック株式会社製)の下を60m/分の速度にて通過させて、印刷面のインキを乾燥させて、評価用サンプルを作製した。
評価用サンプルのインキ転移状態を目視にて判定を行った。下記の記号を用いてインキ転移評価の結果を示す。
○:転移不良が発生せず良好。
×:転移不良が発生して不良。
評価用サンプルの印刷面に、18mm幅のセロハン粘着テープ(株式会社ニチバン製、製品名:CT405AP-18)を5cmの長さで貼り付け、高速手剥離を行いインクの剥がれを目視にて確認し、判定を行った。下記の記号を用いてインキ密着評価の結果を示す。
○:手剥離を実施した部分の100%の面積でインクが残った。又はインクの密着が強すぎて熱可塑性樹脂フィルムが材破した。
△:手剥離を実施した部分の50~100%の面積でインクが残った。
×:手剥離を実施した部分の0~50%の面積でインクが残った。
各実施例、比較例で得られたフィルムをA3サイズに断裁し、オフセット印刷機(リョービ株式会社製、機器名:RYOBI3300CR)、UVオフセット印刷用インキ(T&K TOKA株式会社製、製品名:BC161)を用いて、2000枚印刷した。得られた印刷物にUV(照射量100mJ/cm2)を照射し、インキを固化させて、評価用サンプルを作製した。
評価用サンプルのインキ転移状態を目視にて判定した。下記の記号を用いてインキ転移評価の結果を示す。
○:転移不良が発生せず良好。
×:転移不良が発生して不良。
評価用サンプルの印刷面に、18mm幅のセロハン粘着テープ(株式会社ニチバン製、製品名:CT405AP-18)を5cmの長さで貼り付け、高速手剥離を行いインクの剥がれを目視にて判定した。下記の記号を用いてインキ密着評価の結果を示す。
○:手剥離を実施した部分の100%の面積でインクが残った。又はインクの密着が強すぎて熱可塑性樹脂フィルムが材破した。
△:手剥離を実施した部分の50~100%の面積でインクが残った。
×:手剥離を実施した部分の0~50%の面積でインクが残った。
各実施例、比較例で得られたフィルムを、横60mm、縦110mmの矩形に打抜加工することで、ラベル付きプラスチック容器の製造に用いるラベルを作製した。準備したラベルを、ブロー成形用の一対の金型の一方の内側の面に固定した。上記金型は、400mlの内容量のボトルを成型できる金型を用いた。ラベルは、ラベルのヒートシール層がキャビティ側に向くように配置し、吸引を利用して金型上に固定した。
得られたラベル付きプラスチック容器の外観を目視にて確認し、後述の記号を用いて160℃接着性を評価した。
・200℃接着性
高密度ポリエチレンを200℃で溶融してパリソン状に押し出した以外は、160℃接着性の評価に用いたラベル付きプラスチック容器と同様の方法により、200℃接着性の評価に用いるラベル付きプラスチック容器を作製した。
得られたラベル付きプラスチック容器の外観を目視にて確認し、後述の記号を用いて200℃接着性を評価した。
○:ブリスターなく綺麗に接着する。
△:接着するが4本中1本以下の割合でブリスターが発生する。
×:接着強度が弱い、もしくは4本中2本以上の割合でブリスターが発生する。
200℃接着性の評価に用いたラベル付きプラスチック容器の外観を目視にて確認し、後述の記号を用いてオレンジピールを評価した。
○:斜光をあてても凹凸が目立たない。
△:斜光を当てた際に凹凸が目立ち、凹凸の間隔が0.5mm未満である。
×:斜光を当てた際に凹凸が目立ち、凹凸の間隔が0.5mm以上である。
表1に、フィルム成形に使用した材料とその物性を示す。無機微細粉末の平均粒径はBET比表面積から求められる粒径であり、D50はマイクロトラックHRA(日機装株式会社社製)による体積分布の累積値50%における粒径(体積平均粒径と称される場合がある。)を示し、D90は同じく累積値90%における粒径(体積平均粒径と称される場合がある。)を示す。
(フィルム成形)
多孔質層の材料として、表1に記載の高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)を質量比30:70:1で混合し、これを180℃に設定した押出機にて溶融混練した後、190℃に設定したTダイに供給し、シート状に押し出した。押し出されたシートを冷却ロールにて約40℃まで冷却して、296μmの無延伸シートを得た。次に、無延伸シートを、110℃に再加熱した後、ロール群の周速差を利用して縦方向に2倍延伸(MD延伸)し、引き続きテンターオーブンを用いて128℃に再加熱した後、テンターを用いて横方向に2倍延伸(TD延伸)した。その後、130℃に調整した熱セットゾーンによりアニーリング処理を行い、冷却ロールにて約60℃まで冷却し、耳部をスリットして、多孔質層単層で構成される2軸延伸HDPEフィルムを得た。
(インモールド評価)
実施例1のフィルムについて、上述の方法でパリソン温度160℃及び200℃でインモールド成形して得られたラベル付きプラスチック容器の評価を行った。160℃接着性:○、200℃接着性:○、オレンジピール:○であり良好であった。
(フィルム成形)
実施例1において、MD延伸温度およびTD延伸温度を表2又は表3のとおり変更したこと以外は実施例1と同様にして、実施例2~3及び比較例1のフィルムを作製した。なお、比較例1のフィルムは、延伸むらが顕著であり、実用に耐えないと判断した。そのため、比較例1のフィルムについては、フィルムの物性値を測定していない。また、IML適性、フレキソ印刷適性及びオフセット印刷適性についても評価していない。
(インモールド成形評価)
得られた実施例2~3のフィルムについて、インモールド適性に関する評価(インモールド成形評価と称する場合がある。)を実施した。いずれも実施例1と同様に接着性、オレンジピールとも良好な結果を得た。
(フィルム成形)
実施例1において、冷却ロールにおける引き取り速度を増速して無延伸シートの厚さを表2又は表3の通りに変更したこと以外は、実施例1と同様にして実施例4、比較例2のフィルムを作製した。
(インモールド成形評価)
作製したフィルムについて、インモールド成形評価を実施した。結果を表2又は表3に示す。空孔長が20μmを下回ると断熱性が不足してIML適性が低下した。
(フィルム成形)
実施例1において、成分Aの熱可塑性樹脂、成分Bの重質炭酸カルシウムを表2の通り変更したこと以外は、実施例1と同様にして実施例5~6のフィルムを作製した。
(インモールド成形評価)
作製したフィルムについて、インモールド成形評価を実施した。結果を表2に示す。多孔質層の配合を変更したが、実施例1に劣らない評価が得られた。
(フィルム成形)
実施例1において、多孔質層における熱可塑性樹脂(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)の配合量を表2のとおり変更し、多孔質層の空孔率が35~40%になるように無延伸シートの厚さ及び延伸条件を調整して、実施例7のフィルムを作製した。
(インモールド成形評価)
作製したフィルムについて、インモールド成形評価を実施した。結果を表2に示す。多孔質層における無機微細粉末の含有量を下げた場合、延伸倍率を上げる等調整して空孔長を確保すればIML適性が発現していることが分かる。しかしながら、凹凸の間隔が0.5mm未満のオレンジピールが生じた。
(フィルム成形)
多孔質層の材料として、表1に記載の高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)を質量比75:25:1で混合し、同方向二軸混練機で混練して多孔質層用の熱可塑性樹脂組成物ペレットを得た。一方、高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤を質量比80:20:0.5で混合し、同方向二軸混練機にて混練して表面層用の熱可塑性樹脂組成物ペレットを得た。
(インモールド成形評価)
作製したフィルムについて、インモールド成形評価を実施した。結果を表3に示す。無機微細粉末の含有量が35質量%を下回る従来型のインモールドフィルムは、接着性を発現するためには延伸倍率を大きくするだけでは不十分であり、しかも、凹凸の間隔が0.5mm以上のオレンジピールが発生した。
(フィルム成形)
2種3層無延伸シートの厚さを1248μmにしたこと以外は比較例3と同様にして、比較例4の2種3層2軸延伸HDPEフィルムを作製した。比較例4のフィルムは厚さDが130μm、熱抵抗値Rtが0.12m2・K/Wであり、多孔質層は厚さdが118μmであり、密度ρが0.677g/m3であり、空孔率pが39%であり、空孔長Lが51μmであり、平滑度sが101秒であり、表面抵抗値Rsが1.1×1016Ωであった。
作製したフィルムについて、インモールド成形評価を実施した。結果を表3に示す。比較例3のフィルムと比較して厚さdが増加したことにより、空孔長Lが大きくなり、IML適性が発現した。しかし、空孔サイズが大きく、凹凸の間隔が0.5mm以上のオレンジピールが発生した。
(フィルム成形)
実施例1において、多孔質層における熱可塑性樹脂(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)の配合量を20:80:1に変更し、フィルムの作製を試みた。しかし、分散媒となる熱可塑性樹脂が少なく、Tダイで成形した無延伸シートが脆くなり縦延伸することが不可能であった。そのため、比較例5のフィルムについては、フィルムの物性値を測定していない。また、IML適性、フレキソ印刷適性及びオフセット印刷適性についても評価していない。
(フィルム成形)
多孔質層の材料として、表1に記載の高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)を質量比30:70:1で混合し、同方向二軸混練機で混練して多孔質層用の熱可塑性樹脂組成物ペレットを得た。一方、高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤を質量比80:20:0.5で混合し、同方向二軸混練機にて混練して表面層用の熱可塑性樹脂組成物ペレットを得た。
実施例8のフィルムをエポキシ樹脂で包埋し、ミクロトームで切断して断面測定用の試料を作製した。次に上記の試料を、走査型電子顕微鏡(日本電子株式会社製、機器名:JSM-6490)を使用して断面を観察し、観察像から境界線を判別した。フィルム全体の厚さDに対する、多孔質層の厚さdの比率は42%であった。上記の比率から、多孔質層の厚さdを55μmと決定した。
(インモールド成形評価)
作製したフィルムについて、インモールド成形評価を実施した。それらの結果を表2に示す。空孔長が20μmに近いことから、断熱性が低くIML適性は△を示した。一方、延伸倍率が2×2倍であり空孔のサイズが小さく、オレンジピールは生じなかった。接着層を設けたことにより平滑度sは上昇したが、接着層とプラスチック容器との間に空気の混入は見られなかった。
(フィルム成形)
多孔質層の材料として、表1に記載の高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤(分散剤および酸化防止剤)を質量比30:70:1で混合し、同方向二軸混練機で混練して多孔質層用の熱可塑性樹脂組成物ペレットを得た。一方、高密度ポリエチレン(A-1)、重質炭酸カルシウム(B-1)、添加剤を質量比80:20:0.5で混合し、同混練機にて混練して表面層用の熱可塑性樹脂組成物ペレットを得た。
実施例9のフィルムの片面に45W/m2/分の強度でコロナ放電処理を施し、実施例10のフィルムを得た。表面のぬれ張力Wは42mN/mであった。また、実施例9のフィルムの両面に45W/m2/分の強度でコロナ放電処理を施し、引き続き以下の(a)を 0.5質量%、(b)を0.4質量%および(c)を0.5質量%含む水溶液(表面処理剤)を、単位面積(m2)当たり乾燥後0.01gの帯電防止剤が含有するようにサイズプレス方式にて塗工し、70℃で乾燥して、実施例11のフィルムを得た。表面のぬれ張力Wは70mN/mであった。
表面処理剤には以下の材料(a)~(c)を使用した。
(a)四級窒素含有アクリル系三元共重合体
下記の(a-1)~(a-3)のユニットからなる三級級窒素含有アクリル系三元共重合体を合成し、モノクロル酢酸カリウムで4級化して、両性ポリマーとして得た。なお、三級級窒素含有アクリル系三元共重合体中における(a-1)~(a-3)の含有量を各成分とともに示す。
(a-1)N,N'-ジメチルアミノエチルメタクリルアミド(興人株式会社製):40質量%
(a-2)n-ブチルアクリレート(関東化学株式会社製):35質量%
(a-3)オクタデシルアクリレート(関東化学株式会社製):25質量%
(b)ポリエチレンイミン(日本触媒株式会社製、エポミン-1000(商品名))
(c)水溶性ポリアミンポリアミドのエピクロルヒドリン付加物(星光PMC株式会社製、WS-4024(商品名))
実施例9~11のフィルムについて、インモールド成形評価を行ったところ、いずれも160℃接着性:○、200℃接着性:○、オレンジピール:○であり良好であった。
実施例10のフィルムのコロナ放電処理面及び実施例11のフィルムの片面に対し、フレキソ印刷評価を行ったが、インキ転移性およびインキ密着性が○で良好であった。
(オフセット印刷評価)
実施例10のフィルムのコロナ放電処理面に対しオフセット印刷評価を試みたが、シート同士が静電気によって張り付き給紙できなかったため、評価を中止した。実施例11のフィルムの片面に対し、オフセット印刷評価を行った。2000枚印刷し、インキ転移性、インキ密着とも良好であった。
(フィルム成形)
実施例1において、多孔質層層配合の添加剤配合を6質量部に変更したこと以外は実施例1と同様にして実施例12のフィルムを得た。フィルム表面には白い粉が見られた。
(インモールド成形評価)
得られたフィルムについてインモールド成形評価を行った。結果を表2に示す。インモールド適性は実施例2と同等であった。
(フレキソ印刷評価)
得られたフィルムの片面に45W/m2/分の強度でコロナ放電処理を施し、コロナ放電処理面に対し、フレキソ印刷評価を行ったが、インキ転移性およびインキ密着性が不良となった。オフセット印刷評価は実施しなかった。
Claims (18)
- 熱可塑性樹脂を含有するフィルムであって、
下記(A)及び(B)の条件を満たす多孔質層を少なくとも1層有することを特徴とするフィルム。
(A)前記多孔質層は、熱可塑性樹脂25~65質量部と、無機微細粉末35~75質量部とを含む。
(B)下記の式(1)で表される前記多孔質層の空孔長Lは20μm以上である。
L=d×(ρ0-ρ)/ρ0 ・・・式(1)
前記式(1)において、Lは前記多孔質層の空孔長[μm]であり、dは、前記多孔質層の厚さ[μm]であり、ρは、前記多孔質層の密度[g/cm3]であり、ρ0は、前記多孔質層の真密度[g/cm3]である。 - 前記フィルムは、下記(C)の条件をさらに満たす、
請求項1に記載のフィルム。
(C)前記多孔質層の厚さdは、前記フィルムの厚さDの10~100%である。 - 前記多孔質層は、前記熱可塑性樹脂及び前記無機微細粉末の合計100質量部に対して、添加剤0.1~5質量部を含む、
請求項1又は請求項2に記載のフィルム。 - 前記多孔質層の厚さ方向に平行な断面における前記無機微細粉末の表面から空孔壁までの最大距離は50μm以下である、
請求項1から請求項3までの何れか一項に記載のフィルム。 - 前記多孔質層の式(2)で表される空孔率pは15~75%である、
請求項1から請求項4までの何れか一項に記載のフィルム。
p=(ρ0-ρ)/ρ0 ×100・・・式(2)
前記式(2)において、pは前記多孔質の空孔率[%]であり、ρは、前記多孔質層の密度[g/cm3]であり、ρ0は、前記多孔質層の真密度[g/cm3]である。 - 前記多孔質層に含まれる前記熱可塑性樹脂は、ポリオレフィンを主成分とする、
請求項1から請求項5までの何れか一項の何れか一項に記載のフィルム。 - 前記多孔質層が少なくとも1軸方向に延伸されてなる、
請求項1から請求項6までの何れか一項に記載のフィルム。 - 前記フィルムの厚さDは、40~250μmである、
請求項1から請求項7までの何れか一項に記載のフィルム。 - 前記フィルムの少なくとも一方の面の表面抵抗率Rsは、23℃50%RHにおいて1×108~1×1012Ωである、
請求項1から請求項8までの何れか一項に記載のフィルム。 - 前記多孔質層の一方の面の側に配された表面層をさらに有する、
請求項1から請求項9までの何れか一項に記載のフィルム。 - 前記フィルムの前記多孔質層の一方の面の側に配される層の表面に情報が印刷される、
請求項1から請求項10までの何れか一項に記載のフィルム。 - 前記多孔質層の一方の面の側に配された接着層をさらに有し、
前記接着層の表面におけるJIS P 8119:1998で測定される王研式平滑度sは、5~4000秒である、
請求項1から請求項9までの何れか一項の何れか一項に記載のフィルム。 - 前記多孔質層の他方の面の側に配された表面層をさらに有する、
請求項12に記載のフィルム。 - 前記フィルムの前記多孔質層の他方の面の側に配される層の表面に情報が印刷される、
請求項12又は請求項13に記載のフィルム。 - 前記フィルムの前記多孔質層の他方の面の側の表面の表面抵抗率Rsは、23℃50%RHにおいて1×1012Ω以上である、
請求項12から請求項14までの何れか一項に記載のフィルム。 - 前記フィルムの下記の式(3)で表される熱抵抗値Rtは、0.05m2・K/W以上である、
請求項1から請求項15までの何れか一項に記載のフィルム。
Rt=D×10-6/λ・・・式(3)
前記式(3)において、Rtは前記フィルムの熱抵抗値[m2・K/W]であり、Dは前記フィルムの厚さ[μm]であり、λは前記フィルムの熱伝導率[W/m・K]である。 - 請求項1から請求項16までの何れか一項に記載のフィルムをインモールド成形により貼着してなるラベル付きプラスチック容器。
- 下記の式(4)の関係を満足する、
請求項17に記載のラベル付きプラスチック容器。
Tf-10≦Tv≦Tf+60 ・・・式(4)
前記式(4)において、Tvは、前記ラベル付きプラスチック容器の容器本体の最表面に含まれる熱可塑性樹脂の融点であり、Tfは、前記フィルムの前記容器本体に接する層に含まれる熱可塑性樹脂の融点である。
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