WO2023022193A1 - Hot melt adhesive - Google Patents

Hot melt adhesive Download PDF

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Publication number
WO2023022193A1
WO2023022193A1 PCT/JP2022/031202 JP2022031202W WO2023022193A1 WO 2023022193 A1 WO2023022193 A1 WO 2023022193A1 JP 2022031202 W JP2022031202 W JP 2022031202W WO 2023022193 A1 WO2023022193 A1 WO 2023022193A1
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WIPO (PCT)
Prior art keywords
hot melt
mass
melt adhesive
block copolymer
styrene
Prior art date
Application number
PCT/JP2022/031202
Other languages
French (fr)
Inventor
Atsushi Kakuda
Tadashi Hayakawa
Original Assignee
Henkel Ag & Co. Kgaa
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Filing date
Publication date
Application filed by Henkel Ag & Co. Kgaa filed Critical Henkel Ag & Co. Kgaa
Publication of WO2023022193A1 publication Critical patent/WO2023022193A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J153/00—Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • C09J153/02—Vinyl aromatic monomers and conjugated dienes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure

Definitions

  • the present invention relates to a hot melt adhesive, and more particularly to a hot melt adhesive for use in the field of disposable products such as disposable diapers and napkins.
  • Hot melt adhesives are used in disposable products such as disposable diapers and napkins. Hot melt adhesives are applied to substrates such as non-woven fabric, tissue and polyethylene film, and a plurality of these substrates is combined to produce a disposable product.
  • thermoplastic block copolymers and olefin based hot melt adhesives such as ethylene/propylene/butene copolymers may be mainly exemplified.
  • synthetic rubber-based hot melt adhesives may be used rather than olefin-based adhesives.
  • hot melt adhesives include a base polymer and a plasticizer. It has been studied to reduce the viscosity of the hot melt adhesive and improve the coating suitability by reducing the amount of the base polymer and increasing the amount of the plasticizer.
  • a hot melt adhesive containing a large amount of the plasticizer has a problem that it has a poor balance between the cohesive force and the tack and the adhesiveness to a paper diaper member (for example, a polyethylene film) is lowered.
  • a hot melt adhesive is used when a stretched rubber thread is bonded to a disposable diaper body.
  • the disposable diaper body being composed of a material having no elasticity, the disposable diaper body to which the rubber thread is bonded is folded by the shrinkage force of the rubber thread when the rubber thread shrinks. As a result, the elastic force of the rubber thread is applied to the disposable diaper body, and the disposable diaper fits the body.
  • a hot melt adhesive that bonds an elastic material such as a rubber thread to a disposable diaper body needs to have excellent creep resistance.
  • the hot melt adhesive is stretched by the shrinkage force of the elastic material, thus the elastic material becomes unable to stay at the position where it is bonded.
  • the hot melt adhesive is required to have excellent creep resistance.
  • Patent Documents 1 to 3 disclose synthetic rubber-based hot melt adhesives based on styrene-based block copolymers.
  • Patent Document 1 discloses a hot melt adhesive comprising a styrene-based block copolymer and an amorphous wax modified with a carboxylic anhydride ([claim 1]).
  • Patent Document 1 discloses a hot melt adhesive having improved creep resistance in a wet state, excellent low temperature coatability and adhesiveness, and capable of reducing odor ([0012], [0018]).
  • the hot melt adhesive of Patent Document 1 does not have sufficient creep resistance to keep a stretched elastic material in the bonded position as it is, and it is difficult to use the elastic material for use in incorporation of the elastic material into a disposable product.
  • Patent Document 2 discloses a hot melt adhesive comprising a radial type styrene block copolymer and a linear type styrene block copolymer ([claim 1]).
  • the hot melt adhesive of Patent Document 2 low temperature coating is possible, and it has excellent creep resistance ([0013], [0020]).
  • consumers have recently demanded better performance on low temperature coating.
  • Patent Document 3 discloses a hot melt composition containing a styrene-based block copolymer and a plasticizer and having no tackifying resin ([0093] Table 1). Patent Document 3 describes to the effect that the content of the tackifying resin in the hot melt composition is preferably 30% by mass or less. By lowering the content of the tackifying resin, the hot melt composition does not become too hard and the stretch recovery after being stretched is improved ([0050]). However, since the content of the tackifying resin is too low, the hot melt composition of Patent Document 3 has a poor balance between tack and cohesive force, and also has a high melt viscosity, which is not suitable for low temperature coating.
  • Patent Document 1 JP 2016-153448 A
  • Patent Document 2 JP 2016-44289 A
  • Patent Document 3 WO 2020/110921 A1
  • the hot melt adhesive that fixes an elastic material to a disposable product body contains a relatively large amount of styrene block copolymers to enhance the cohesive force that achieves creep resistance.
  • the hot melt adhesive tends to have a higher melt viscosity and is inferior in low temperature coatability as compared with a general assembly adhesive.
  • rubber threads and non-woven fabrics, which are materials for disposable products become thin, and plastic films become thin. Since such delicate materials are prone to thermal deterioration, hot melt adhesives are required to have a higher level of low temperature coatability.
  • the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a hot melt adhesive which has excellent low temperature coatability and creep resistance, has a good balance between tack and cohesive force, and is able to bond and keep an elastic material to a non-woven fabric or a plastic film, and a disposable product obtained by using the hot melt adhesive.
  • a hot melt adhesive comprising (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer, wherein (A) the thermoplastic block copolymer comprises the following component (A1) and component (A2): (A1) a styrene isoprene block copolymer having a styrene content of more than 40% by mass; and (A2) a styrene isoprene block copolymer having a styrene content of more than 15% by mass and less than 30% by mass.
  • the hot melt adhesive according to any one of 1 to 5, for use in fixing an elastic material to a disposable product body.
  • a disposable product to which the hot melt adhesive according to any one of 1 to 6 is applied.
  • the hot melt adhesive of the present invention has excellent low temperature coatability and creep resistance, has a good balance between tack and cohesive force, and is able to bond and keep an elastic material to a non-woven fabric or a plastic film.
  • the hot melt adhesive of the present invention it is possible to manufacture a disposable product in which an elastic material such as a rubber thread is firmly kept to a substrate.
  • the hot melt adhesive of the present invention contains (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer.
  • thermoplastic block copolymer is a copolymer in which vinyl aromatic hydrocarbons and conjugated diene compounds are block-copolymerized.
  • thermoplastic block copolymer is usually a resin composition containing a copolymer having a vinyl aromatic hydrocarbon block and a conjugated diene compound block.
  • the "vinyl aromatic hydrocarbon” means an aromatic hydrocarbon compound having a vinyl group, and specifically, for example, styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, ⁇ -methylstyrene, vinylnaphthalene, vinylanthracene and the like may be exemplified. The most preferred among these is styrene. These vinyl aromatic hydrocarbons may be used alone or in combination.
  • the "conjugated diene compound” means a diolefin compound having at least a pair of conjugated double bonds.
  • 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentaziene and 1,3-hexadiene may be exemplified as the "conjugated diene compound".
  • the preferred among these are 1,3-butadiene and 2-methyl-1,3-butadiene.
  • These conjugated diene compounds may be used alone or in combination.
  • thermoplastic block copolymer according to the present invention may be an unhydrogenated product or a hydrogenated product.
  • thermoplastic block copolymer examples include, specifically, those in which a block based on conjugated diene compounds is not hydrogenated.
  • hydrogenated product of the thermoplastic block copolymer examples include, specifically, a block copolymer to which all or part of a block based on conjugated diene compounds is hydrogenated.
  • the hydrogenated ratio of "(A) the hydrogenated product of the thermoplastic block copolymer” may be indicated by the "hydrogenation ratio".
  • the “hydrogenation ratio” of "(A) the hydrogenated product of the thermoplastic block copolymer” means the ratio of the double bonds having been converted to saturated hydrocarbon bonds by hydrogenation, based on the total aliphatic double bonds contained in the blocks derived from the conjugated diene compounds. This "hydrogenation ratio" may be measured by an infrared spectrophotometer, a nuclear magnetic resonance apparatus, or the like.
  • thermoplastic block copolymer examples include, specifically, a styrene-isoprene block copolymer (also referred to as "SIS”) and a styrene-butadiene block copolymer (also referred to as "SBS”).
  • SIS styrene-isoprene block copolymer
  • SBS styrene-butadiene block copolymer
  • SEBS hydrogenated styrene-butadiene block copolymer
  • thermoplastic block copolymer includes a linear type styrene block copolymer or a radial type styrene block copolymer.
  • linear type means a linear structure.
  • the linear type styrene block copolymer is a linear copolymer in which a styrene block and a conjugated diene block are bonded.
  • the radial type styrene block copolymer is a branched styrene block copolymer having a structure in which a plurality of linear type styrene block copolymers projects radially around a coupling agent.
  • n is an integer of 2 or more
  • S is a styrene block
  • E is a conjugated diene compound block
  • Y is a coupling agent.
  • n is preferably 3 or 4, and n is particularly preferably 3.
  • Butadiene or isoprene is preferred as the conjugated diene compound.
  • the styrene block copolymer is a resin composition and contains the styrene-conjugated diene block copolymer represented by formula (2) in a certain ratio.
  • the coupling agent is a polyfunctional compound that radially bonds linear type styrene block copolymers.
  • the type of coupling agent is not particularly limited.
  • the coupling agent examples include silane compounds such as halogenated silanes and alkoxysilanes; tin compounds such as tin halides; polycarboxylate esters; epoxy compounds such as epoxidized soybean oils; acrylates such as pentaerythritol tetraacrylate; epoxysilanes; divinyl compounds such as divinylbenzene; and the like.
  • Specific examples include trichlorosilane, tribromosilane, tetrachlorosilane, tetrabromosilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, and tetrachlorotin, diethyladipate and the like.
  • the thermoplastic block copolymer contains (A1) a styrene isoprene block copolymer.
  • the component (A1) preferably has a styrene content of more than 40% by mass.
  • the component (A1) may have a styrene content of, for example, 41 to 50% by mass, preferably 43 to 48% by mass, and more preferably 44 to 46% by mass.
  • styrene content means the ratio of styrene blocks contained in a certain type of block copolymer.
  • the styrene content of the component (A1) is in the above range, so that the hot melt adhesive has increased retention force (cohesive force) and excellent creep resistance, and thereby, the hot melt adhesive is able to bond and keep an elastic material having high stretch ratio to the disposable product body.
  • the thermoplastic block copolymer further comprises (A2) a styrene isoprene block copolymer that is a different type from the component (A1).
  • the component (A2) preferably has a styrene content of more than 15% by mass and less than 30% by mass.
  • the component (A2) may have a styrene content of, for example, 16 to 29% by mass, preferably 18 to 27% by mass, and more preferably 19 to 25% by mass.
  • the styrene content of the component (A2) is in the above range, and thereby, the hot melt adhesive has excellent tack, and also has better adhesiveness while maintaining the balance between the cohesive force and the tack.
  • the styrene content of the component (A1) and the component (A2) is in the above range, and thereby, the balance between the cohesive force and the tack is improved, and the adhesiveness is improved.
  • the diblock content of the component (A1) is preferably 0 to 20% by mass, and preferably 0% by mass.
  • the linear type styrene block copolymer having a diblock content of 0% by mass is referred to as a triblock type styrene block copolymer.
  • the "diblock content” means the ratio of the styrene-conjugated diene compound block copolymer of formula (2) contained in a certain type of block copolymer.
  • the diblock content of the component (A2) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and desirably 0% by mass.
  • the diblock contents of the component (A1) and the component (A2) are in the above ranges, and thereby, the balance between the cohesive force and the tack becomes better, resulting in excellent adhesiveness.
  • the weight-average molecular weight of the component (A1) is preferably 50,000 to 150,000, particularly preferably 50,000 to 120,000, and particularly preferably 70,000 to 100,000.
  • the weight-average molecular weight of the component (A1) is in the above range, and thereby, the cohesive force is increased, and the creep resistance and the adhesiveness are more improved while having the balance between the tack and the cohesive force.
  • the weight-average molecular weight of the component (A2) is preferably 80,000 to 500,000, particularly preferably 100,000 to 300,000, and particularly preferably 120,000 to 200,000.
  • the weight-average molecular weight of the component (A2) is in the above range, and thereby the tack is increased, and the creep resistance and the adhesiveness are more improved, while having the balance between the tack and the cohesive force.
  • the weight-average molecular weight (Mw) means a value measured by gel permeation chromatography (GPC). Specifically, the value can be measured using the following device and measuring method. RI manufactured by Tosoh Corporation is used as a detector. As a GPC column, TSK Gel Super HZ-M manufactured by Tosoh Corporation is used. A sample is dissolved in tetrahydrofuran, which was flowed at a flow rate of 0.35 mL/min, a measurement temperature of 40ºC, and the molecular weight is converted with a calibration curve for polystyrene to find the weight-average molecular weight.
  • GPC gel permeation chromatography
  • the molecular weight distribution is also calculated by GPC. Not only the component (A1) but also the Mw, Mn, and molecular weight distributions of other components can be obtained by the same method.
  • the component (A1) and the component (A2) are preferably linear styrene block copolymers, and particularly preferably triblock styrene isoprene block copolymers.
  • the structures of the component (A1) and the component (A2) are linear type, and thereby, it is able to bond and keep more strongly an elastic material such as a rubber thread to a material such as a film or a non-woven fabric for disposable products.
  • GP5562U (trade name) manufactured by LCY Chemical Corporation
  • VECTOR 4411AS (trade name) manufactured by TSRC Corporation
  • Kraton D1162PT (trade name) manufactured by Kraton Corporation
  • Quintac 3191 (trade name) manufactured by Zeon Corporation.
  • the component (A2) may be a linear type styrene isoprene block copolymer or a radial type styrene isoprene block copolymer.
  • the component (A2) contains a linear type styrene isoprene block copolymer, so that the tack is improved, and the adhesiveness is more improved while maintaining the balance between the cohesive force and the tack.
  • JH8291 (trade name) manufactured by Jinhai Chemical Corporation
  • Quintac 3280 (trade name)
  • Quintac 3450 (trade name)
  • VECTOR 4111 (trade name) manufactured by TSRC Corporation
  • the component (A) may contain (A3) other styrene block copolymers (not corresponding to the component (A1) or the component (A2)).
  • the component (A1) is contained in an amount of preferably 5 to 40 parts by mass, more preferably 10 to 25 parts by mass, and more preferably 13 to 22 parts by mass based on 100 parts by mass of the total amount of the components (A), (B) and (C).
  • the content of the component (A1) is in the above range, and thereby, the cohesive force of the hot melt adhesive is more improved, and the creep resistance is improved.
  • the component (A2) is contained in an amount of preferably 0.5 to 20 parts by mass, more preferably 2 to 10 parts by mass, and further preferably 3 to 9 parts by mass, based on 100 parts by mass of the total amount of the components (A), (B) and (C).
  • the content of the component (A2) is in the above range, and thereby, the tack of the hot melt adhesive is more improved, and the adhesive strength is improved.
  • the hot melt adhesive of the present invention contains (B) a tackifying resin.
  • the tackifying resin is not particularly limited as long as the object of the present invention is achieved as an additive for the hot melt adhesive, but it is desirable that it is a hydrogenated resin.
  • the tackifying resin for example, natural rosins, modified rosins, hydrogenated rosins, glycerol esters of natural rosins, glycerol esters of modified rosins, pentaerythritol esters of natural rosins, pentaerythritol esters of modified rosins, pentaerythritol esters of hydrogenated rosins, copolymers of natural terpenes, three-dimensional polymers of natural terpenes, hydrogenated derivatives of copolymers of hydrogenated terpenes, polyterpene resins, hydrogenated derivatives of phenolic modified terpene resins, aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petroleum hydrocarbon resins, alicyclic petroleum hydrocarbon resins, hydrogenated derivatives of alicyclic petroleum hydrocarbon resins and the like may be
  • tackifying resins may be used alone or in combination.
  • a liquid type tackifying resin may also be used as long as the color tone is colorless to pale yellow, there is substantially no odor, and the compatibility with other components is good.
  • hydrogenated derivatives of petroleum hydrocarbon resins are preferred as the tackifying resin, and hydrogenated dicyclopentadiene-based resins are particularly preferred.
  • the commercially available products of (B) the tackifying resin include T-Rez HA103 (trade name), T-Rez HB125 (trade name), T-Rez HC103 (trade name) manufactured by JXTG, HD1120 (trade name), HD1100 (trade name) manufactured by Zibo Luhua Hongjin New Material Corporation, ECR5600 (trade name) manufactured by Exxon Mobil Corporation, Eastotac H130 (trade name), Plastolyn 290LV (trade name) manufactured by Eastman Corporation, SUKOREZ SU420 (trade name), SUKOREZ SU400 (trade name) manufactured by Kolon Industries, Inc. Imarv S100 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Alcon M100 (trade name), Alcon P115 (trade name) manufactured by Arakawa Chemical Industries, Ltd. and the like.
  • the tackifying resin is contained in an amount of preferably 40 to 70 parts by mass, and more preferably 45 to 65 parts by mass based on 100 parts by mass of the total amount of the components (A), (B) and (C).
  • the hot melt adhesive of the present invention has a better balance between the cohesive force and the tack.
  • the hot melt adhesive of the present invention preferably contains (C) a plasticizer in addition to the component (A) and the component (B).
  • the plasticizer is formulated for the purpose of lowering the melt viscosity of the hot melt adhesive, imparting flexibility thereof, and improving the wetting to the adherend, thereby improving the coatability of the hot melt adhesive.
  • the plasticizer may include, for example, a paraffinic oil, a naphthenic oil and an aromatic oil.
  • plasticizers for example, White Oil Broom 350 (trade name) manufactured by Kukdong Oil & Chemical Co., Ltd, Diana Fresia S32 (trade name), Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Enerper M1930 (trade name) manufactured by BP Chemicals Ltd., Kaydol (trade name) manufactured by Crompton Corporation, Primol 352 (trade name) manufactured by ESSO CORPORATION, Process Oil NS100 manufactured by Idemitsu Kosan Co., Ltd., and KN4010 (trade name) manufactured by Petro China Company Limited may be exemplified. These plasticizers may be used alone or in combination.
  • the plasticizer is contained in an amount of preferably 10 to 30 parts by mass, and more preferably 15 to 25 parts by mass, based on 100 parts by mass of the total amount of the components (A), (B) and (C).
  • the hot melt adhesive of the present invention has a reduced melt viscosity, and suitable low temperature coatability.
  • the hot melt adhesive according to the present invention may further contain various additives as necessary.
  • various additives for example, stabilizers and fine particle fillers may be exemplified.
  • the stabilizer is formulated in order to improve the stability of the hot melt adhesive by preventing the decrease in molecular weight, gelation, coloring, generation of odor and the like of the hot melt adhesive due to heat. It is not particularly limited as long as the intended hot melt adhesive of the present invention may be obtained.
  • antioxidants and ultraviolet absorbers may be exemplified as the "stabilizer".
  • the ultraviolet absorbers are used to improve the light resistance of hot melt adhesives.
  • the "antioxidants” are used to prevent oxidative deterioration of hot melt adhesives.
  • the antioxidants and ultraviolet absorbers may be used without being particularly limited as long as they are generally used for disposable products, and the intended disposable products described below may be obtained.
  • antioxidants for example, phenolic antioxidants, sulfur antioxidants, and phosphoric antioxidants may be exemplified.
  • ultraviolet absorbers for example, benzotriazole-type ultraviolet absorbers and benzophenone-type ultraviolet absorbers may be exemplified.
  • lactone-based stabilizers may be added. These may be used alone or in combination.
  • SUMILIZER GM (trade name), SUMILIZER TPD (trade name) and SUMILIZER TPS (trade name) manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED
  • Irganox 1010 (trade name), Irganox HP2225FF (trade name), Irgafos 168 (trade name) and Irganox 1520 (trade name) manufactured by Ciba Specialty Chemicals Co.
  • JF77 trade name manufactured by JOHOKU CHEMICAL CO., LTD.
  • These stabilizers may be used alone or in combination.
  • the hot melt adhesive of the present invention is produced by formulating the above components in a predetermined ratio, further formulating various additives as necessary, heating, melting and mixing them. Specifically, it is produced by putting the above-mentioned components into a melting and mixing kettle equipped with a stirrer, and heating and mixing them.
  • the obtained hot melt adhesive has a softening point of preferably 85ºC or more, more preferably 90ºC or more, and still more preferably 95ºC or more.
  • the hot melt adhesive of the present invention has a softening point in the above range, resulting in excellent creep resistance.
  • the "softening point” is measured by the ring and ball method (the method described in the Japan Adhesive Industry Association standard JAI-7-1999).
  • the obtained hot melt adhesive has a melt viscosity at 140°C of preferably less than 7,000 mPa second, more preferably less than 6,500 mPa second, and further preferably less than 6000 mPa second.
  • the hot-melt adhesive of the present invention has a melt viscosity in the above range, resulting in excellent low temperature coatability.
  • melt viscosity means the viscosity of the melt of the hot melt adhesive. It is measured with a Brookfield RVT viscometer (spindle No. 27).
  • the strain in the dynamic viscoelasticity measurement is preferably less than 8%, and more preferably less than 5%.
  • the strain when the strain is less than 8%, by bonding and keeping the stretched rubber thread, a material with no elasticity is able to stretch and shrink, which is suitable for use in disposable products.
  • the hot melt adhesive according to the present invention is widely used for paper processing, bookbinding, disposable products and the like, but is mainly used for disposable products.
  • the "disposable product” is not particularly limited as long as it is a so-called sanitary material, for example.
  • sanitary material disposable diapers, sanitary napkins, pet sheets, hospital gowns, and surgical lab coats and the like may be specifically exemplified.
  • the hot melt adhesive of the present invention is preferably used for the purpose of bonding a stretched elastic material to a product body when manufacturing the disposable product in which the elastic material is incorporated.
  • a disposable product obtained by applying the above-mentioned hot melt adhesive.
  • the disposable product is composed by bonding at least one member selected from the group consisting of woven fabric, non-woven fabric, rubber, resin and paper, and a polyolefin film, using the hot melt adhesive according to the present invention.
  • the polyolefin film is preferably a polyethylene film because of its durability and cost.
  • a hot melt adhesive is generally applied to at least one of various members (for example, non-woven fabric and the like) of a disposable product and a polyolefin film, and the film and the member are pressure bonded to manufacture a disposable product.
  • the hot melt adhesive may be squirted from various squirts and used.
  • the coating may be either contact coating or non-contact coating.
  • Contact coating is a coating method in which an ejector is brought into contact with a member or a film when applying a hot melt adhesive. Specifically, V-slit coating is cited.
  • Non-contact coating is a coating method in which the ejector is not brought into contact with a member or a film when applying a hot melt adhesive.
  • spiral coating that may be applied in a spiral shape
  • omega coating and control seam coating that may be applied in a wavy shape
  • slot spray coating and curtain spray coating that may be applied in a planar shape
  • dot coating that may be applied in a dot form and the like may be exemplified as specific non-contact coating methods.
  • A Thermoplastic block copolymer (A1) Styrene isoprene block copolymer having a styrene content of more than 40% by mass (A1-1) Linear type styrene isoprene block copolymer (GP 5562U (trade name), styrene content 45% by mass, diblock content 0% by mass (triblock content 100% by mass), weight-average molecular weight 94600, manufactured by LCY Chemical Corporation)
  • B Tackifying resin
  • HD1100 Hydrogenated dicyclopentadiene resin (HD1100 (trade name), softening point 100°C, manufactured by Zibo Luhua Hongjin New Material Corporation)
  • D Antioxidant (D1) Phenolic antioxidant (Irganox 1010, manufactured by BASF Corporation))
  • Softening point is 95°C or more B (Good): Softening point is 90°C or more and less than 95°C C (Fair): Softening point is 85°C or more and less than 90°C D (Fail): Softening point is less than 85°C
  • a hot melt adhesive was applied to a polyethylene terephthalate (PET) film having a thickness of 50 ⁇ m to prepare an adhesive layer having a thickness of 50 ⁇ m. This was formed to have a width of 25 mm, and it served as a test piece. This test piece was applied to a polyethylene film having a thickness of 100 ⁇ m at room temperature. When pasting them together, a roller weighing 2 kg was brought into contact with the PET film at a speed of 5 mm/sec.
  • PET polyethylene terephthalate
  • test piece After leaving the test piece to stand at room temperature for 12 hours, it was peeled off in the 180° direction under the conditions of 25°C and a tensile speed of 300 mm/min., and the strength at which the test piece was peeled from the polyethylene (PE) film was measured.
  • the evaluation criteria are as follows.
  • ⁇ Loop tack (adhesive strength)> A hot melt adhesive was applied to a PET film having a thickness of 50 ⁇ m so as to have a thickness of 50 ⁇ m.
  • This PET film was cut into a size of 25 mm ⁇ 145 mm to produce a sample.
  • This sample was wound in a loop shape so that the pressure-sensitive adhesive surface (adhesive-applied surface) was on the outside, and this was brought into contact with the PE plate at a speed of 300 mm/min at 30°C. After that, the test piece was peeled from the PE plate at a speed of 300 mm/min, and the peeling strength at that time was measured, and this was used as a loop tack.
  • the evaluation criteria are shown below.
  • Loop tack is 2500 (g/25 mm) or more
  • This test piece was applied to a polyethylene film having a thickness of 100 ⁇ m so that the bonded area was 1.0 cm ⁇ 1.0 cm, and then they were pressure bonded at 40°C and 0.2 MPa for 3 seconds, followed by being left at 20°C for 12 hours. After being left to stand, a load was applied vertically with a 1 kg weight in an atmosphere of 40°C, and the time until the weight fell was measured, and this was used as the retention force.
  • the evaluation criteria are shown below.
  • Retention force is 300 minutes or more B (Good): Retention force is 200 minutes or more and less than 300 minutes C (Fair): Retention force is 150 minutes or more and less than 200 minutes D (Fail): Retention force is less than 150 minutes
  • ⁇ Creep resistance> The dynamic viscoelasticity of the hot melt adhesive was measured using a dynamic viscoelasticity measuring device (Reometer AR-G2 (trade name) manufactured by TA Instruments LLC), and the creep resistance was evaluated.
  • the specific method is as follows.
  • the hot melt adhesive was heated with a measuring device jig to obtain a cylindrical molded body having a diameter of 8 mm and a thickness of 2000 ⁇ m.
  • This test piece was sandwiched between stainless steel parallel plates, a constant frequency of 1.0 Hz was applied at 40°C, and oscillation measurement was performed. Then, a torque of 100 ⁇ N·m was applied to the test piece, strain (%) after 120 seconds was found, and creep resistance was evaluated. The evaluation criteria are shown below.
  • the hot melt adhesives of the examples have an excellent balance of coatability, peel strength, loop tack, retention force, creep resistance, and particularly have extremely excellent performance in creep resistance.
  • the hot melt adhesives of the comparative examples are evaluated as D (Fail) in any of the coatability, peel strength, loop tack, retention force, and creep resistance.
  • the hot melt adhesive of the invention of the present application has an excellent balance of coatability, peel strength, loop tack, retention force, creep resistance, and particularly has extremely excellent performance in creep resistance, it is suitable for keeping the elastic material to the disposable product.
  • the present invention provides a hot melt adhesive and a disposable product obtained by applying the hot melt adhesive.
  • the hot melt adhesive according to the present invention is suitable for manufacturing disposable products, and is particularly able to keep an elastic material to a disposable product.

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Abstract

To provide a hot melt adhesive having excellent low temperature coatability and creep resistance, a good balance between tack and cohesive force, and being able to bond and keep an elastic material to a non-woven fabric or a plastic film. A hot melt adhesive comprising (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer, wherein (A) the thermoplastic block copolymer comprises the following component (A1) and component (A2): (A1) a styrene isoprene block copolymer having a styrene content of more than 40% by mass; and (A2) a styrene isoprene block copolymer having a styrene content of more than 15% by mass and less than 30% by mass.

Description

HOT MELT ADHESIVE
The present invention relates to a hot melt adhesive, and more particularly to a hot melt adhesive for use in the field of disposable products such as disposable diapers and napkins.
Hot melt adhesives are used in disposable products such as disposable diapers and napkins. Hot melt adhesives are applied to substrates such as non-woven fabric, tissue and polyethylene film, and a plurality of these substrates is combined to produce a disposable product.
As the hot melt adhesive, synthetic rubber based hot melt adhesives composed as a main component of thermoplastic block copolymers and olefin based hot melt adhesives such as ethylene/propylene/butene copolymers may be mainly exemplified. Considering coatability, cohesive force and the like, synthetic rubber-based hot melt adhesives may be used rather than olefin-based adhesives.
Generally, hot melt adhesives include a base polymer and a plasticizer. It has been studied to reduce the viscosity of the hot melt adhesive and improve the coating suitability by reducing the amount of the base polymer and increasing the amount of the plasticizer.
However, a hot melt adhesive containing a large amount of the plasticizer has a problem that it has a poor balance between the cohesive force and the tack and the adhesiveness to a paper diaper member (for example, a polyethylene film) is lowered.
As a kind of disposable diaper, there is the one in which a rubber thread is incorporated. A hot melt adhesive is used when a stretched rubber thread is bonded to a disposable diaper body. The disposable diaper body being composed of a material having no elasticity, the disposable diaper body to which the rubber thread is bonded is folded by the shrinkage force of the rubber thread when the rubber thread shrinks. As a result, the elastic force of the rubber thread is applied to the disposable diaper body, and the disposable diaper fits the body.
A hot melt adhesive that bonds an elastic material such as a rubber thread to a disposable diaper body needs to have excellent creep resistance. When an elastic material is bonded to a paper diaper body using a hot melt adhesive with insufficient creep resistance, the hot melt adhesive is stretched by the shrinkage force of the elastic material, thus the elastic material becomes unable to stay at the position where it is bonded. As a result, only the elastic material shrinks without the paper diaper body, and even if the elastic material shrinks, the paper diaper body is not folded, and the paper diaper does not fit the body. Therefore, the hot melt adhesive is required to have excellent creep resistance.
Patent Documents 1 to 3 disclose synthetic rubber-based hot melt adhesives based on styrene-based block copolymers.
Patent Document 1 discloses a hot melt adhesive comprising a styrene-based block copolymer and an amorphous wax modified with a carboxylic anhydride ([claim 1]). Patent Document 1 discloses a hot melt adhesive having improved creep resistance in a wet state, excellent low temperature coatability and adhesiveness, and capable of reducing odor ([0012], [0018]).
However, the hot melt adhesive of Patent Document 1 does not have sufficient creep resistance to keep a stretched elastic material in the bonded position as it is, and it is difficult to use the elastic material for use in incorporation of the elastic material into a disposable product.
Patent Document 2 discloses a hot melt adhesive comprising a radial type styrene block copolymer and a linear type styrene block copolymer ([claim 1]). In the hot melt adhesive of Patent Document 2, low temperature coating is possible, and it has excellent creep resistance ([0013], [0020]). However, consumers have recently demanded better performance on low temperature coating.
Patent Document 3 discloses a hot melt composition containing a styrene-based block copolymer and a plasticizer and having no tackifying resin ([0093] Table 1). Patent Document 3 describes to the effect that the content of the tackifying resin in the hot melt composition is preferably 30% by mass or less. By lowering the content of the tackifying resin, the hot melt composition does not become too hard and the stretch recovery after being stretched is improved ([0050]). However, since the content of the tackifying resin is too low, the hot melt composition of Patent Document 3 has a poor balance between tack and cohesive force, and also has a high melt viscosity, which is not suitable for low temperature coating.
Prior Art Documents
Patent Documents
[Patent Document 1] JP 2016-153448 A
[Patent Document 2] JP 2016-44289 A
[Patent Document 3] WO 2020/110921 A1
Problem to be solved by Invention
The hot melt adhesive that fixes an elastic material to a disposable product body contains a relatively large amount of styrene block copolymers to enhance the cohesive force that achieves creep resistance. On the other hand, due to the high content of styrene block copolymers, the hot melt adhesive tends to have a higher melt viscosity and is inferior in low temperature coatability as compared with a general assembly adhesive.
In recent years, when manufacturing disposable products, the reduction of manufacturing cost and environmental load, and the soft texture of non-woven fabric products have been emphasized. As a result, rubber threads and non-woven fabrics, which are materials for disposable products, become thin, and plastic films become thin. Since such delicate materials are prone to thermal deterioration, hot melt adhesives are required to have a higher level of low temperature coatability.
As described above, there is a demand for a hot melt adhesive for keeping an elastic material, which has good low temperature coatability, creep resistance, and a balance between tack and cohesive force.
The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a hot melt adhesive which has excellent low temperature coatability and creep resistance, has a good balance between tack and cohesive force, and is able to bond and keep an elastic material to a non-woven fabric or a plastic film, and a disposable product obtained by using the hot melt adhesive.
Means for solving the Problem
The present invention and preferred embodiments of the present invention are as follows.
1. A hot melt adhesive comprising (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer, wherein
(A) the thermoplastic block copolymer comprises the following component (A1) and component (A2):
(A1) a styrene isoprene block copolymer having a styrene content of more than 40% by mass; and
(A2) a styrene isoprene block copolymer having a styrene content of more than 15% by mass and less than 30% by mass.
2. The hot melt adhesive according to 1, wherein the component (A1) comprises a linear type styrene isoprene block copolymer, and the component (A2) comprises a linear type styrene isoprene block copolymer.
3. The hot melt adhesive according to 1 or 2, wherein the component (A1) has a weight-average molecular weight of 50,000 to 150,000.
4. The hot melt adhesive according to any one of 1 to 3, wherein the component (A1) is contained in an amount of 10 to 25 parts by mass, and the component (A2) is contained in an amount of 2 to 10 parts by mass, based on 100 parts by mass of the total of components (A) to (C).
5. The hot melt adhesive according to any one of 1 to 4, wherein (B) the tackifying resin is contained in an amount of 45 to 70 parts by mass, based on 100 parts by mass of the total of the components (A) to (C).
6. The hot melt adhesive according to any one of 1 to 5, for use in fixing an elastic material to a disposable product body.
7. A disposable product to which the hot melt adhesive according to any one of 1 to 6 is applied.
Effect of Invention
The hot melt adhesive of the present invention has excellent low temperature coatability and creep resistance, has a good balance between tack and cohesive force, and is able to bond and keep an elastic material to a non-woven fabric or a plastic film.
By using the hot melt adhesive of the present invention, it is possible to manufacture a disposable product in which an elastic material such as a rubber thread is firmly kept to a substrate.
Embodiment of the Invention
The hot melt adhesive of the present invention contains (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer.
<(A) Thermoplastic Block Copolymer>
In the hot melt adhesive of the present invention, (A) the thermoplastic block copolymer is a copolymer in which vinyl aromatic hydrocarbons and conjugated diene compounds are block-copolymerized.
(A) The thermoplastic block copolymer is usually a resin composition containing a copolymer having a vinyl aromatic hydrocarbon block and a conjugated diene compound block.
Here, the "vinyl aromatic hydrocarbon" means an aromatic hydrocarbon compound having a vinyl group, and specifically, for example, styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene and the like may be exemplified. The most preferred among these is styrene. These vinyl aromatic hydrocarbons may be used alone or in combination.
The "conjugated diene compound" means a diolefin compound having at least a pair of conjugated double bonds. Specifically, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentaziene and 1,3-hexadiene may be exemplified as the "conjugated diene compound". The preferred among these are 1,3-butadiene and 2-methyl-1,3-butadiene. These conjugated diene compounds may be used alone or in combination.
(A) The thermoplastic block copolymer according to the present invention may be an unhydrogenated product or a hydrogenated product.
Examples of "(A) the unhydrogenated product of the thermoplastic block copolymer" include, specifically, those in which a block based on conjugated diene compounds is not hydrogenated. Examples of "(A) the hydrogenated product of the thermoplastic block copolymer" include, specifically, a block copolymer to which all or part of a block based on conjugated diene compounds is hydrogenated.
The hydrogenated ratio of "(A) the hydrogenated product of the thermoplastic block copolymer" may be indicated by the "hydrogenation ratio". The "hydrogenation ratio" of "(A) the hydrogenated product of the thermoplastic block copolymer" means the ratio of the double bonds having been converted to saturated hydrocarbon bonds by hydrogenation, based on the total aliphatic double bonds contained in the blocks derived from the conjugated diene compounds. This "hydrogenation ratio" may be measured by an infrared spectrophotometer, a nuclear magnetic resonance apparatus, or the like.
Examples of "(A) the unhydrogenated product of the thermoplastic block copolymer" include, specifically, a styrene-isoprene block copolymer (also referred to as "SIS") and a styrene-butadiene block copolymer (also referred to as "SBS"). Examples of "(A) the hydrogenated product of the thermoplastic block copolymer" include, specifically, a hydrogenated styrene-isoprene block copolymer (also referred to as "SEPS") and a hydrogenated styrene-butadiene block copolymer (also referred to as "SEBS").
In the present invention, (A) the thermoplastic block copolymer includes a linear type styrene block copolymer or a radial type styrene block copolymer.
In the present description, the "linear type" means a linear structure. The linear type styrene block copolymer is a linear copolymer in which a styrene block and a conjugated diene block are bonded.
The radial type styrene block copolymer is a branched styrene block copolymer having a structure in which a plurality of linear type styrene block copolymers projects radially around a coupling agent.
The specific structure of the radial styrene block copolymer is shown below.
Chemical Formula 1
(S-E)nY (1)
In the formula, n is an integer of 2 or more, S is a styrene block, E is a conjugated diene compound block, and Y is a coupling agent. n is preferably 3 or 4, and n is particularly preferably 3. Butadiene or isoprene is preferred as the conjugated diene compound.
The styrene block copolymer is a resin composition and contains the styrene-conjugated diene block copolymer represented by formula (2) in a certain ratio.
Chemical Formula 2
S-E (2)
In the formula, S and E have the same meaning as above. The styrene-conjugated diene block copolymer represented by formula (2) is sometimes referred to as a "diblock".
The coupling agent is a polyfunctional compound that radially bonds linear type styrene block copolymers. The type of coupling agent is not particularly limited.
Examples of the coupling agent include silane compounds such as halogenated silanes and alkoxysilanes; tin compounds such as tin halides; polycarboxylate esters; epoxy compounds such as epoxidized soybean oils; acrylates such as pentaerythritol tetraacrylate; epoxysilanes; divinyl compounds such as divinylbenzene; and the like.
Specific examples include trichlorosilane, tribromosilane, tetrachlorosilane, tetrabromosilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, and tetrachlorotin, diethyladipate and the like.
(A) The thermoplastic block copolymer contains (A1) a styrene isoprene block copolymer. The component (A1) preferably has a styrene content of more than 40% by mass. The component (A1) may have a styrene content of, for example, 41 to 50% by mass, preferably 43 to 48% by mass, and more preferably 44 to 46% by mass.
As used herein, the term "styrene content" means the ratio of styrene blocks contained in a certain type of block copolymer.
The styrene content of the component (A1) is in the above range, so that the hot melt adhesive has increased retention force (cohesive force) and excellent creep resistance, and thereby, the hot melt adhesive is able to bond and keep an elastic material having high stretch ratio to the disposable product body.
In a preferred embodiment, (A) the thermoplastic block copolymer further comprises (A2) a styrene isoprene block copolymer that is a different type from the component (A1). The component (A2) preferably has a styrene content of more than 15% by mass and less than 30% by mass. The component (A2) may have a styrene content of, for example, 16 to 29% by mass, preferably 18 to 27% by mass, and more preferably 19 to 25% by mass.
The styrene content of the component (A2) is in the above range, and thereby, the hot melt adhesive has excellent tack, and also has better adhesiveness while maintaining the balance between the cohesive force and the tack.
In the hot melt adhesive of the present invention, the styrene content of the component (A1) and the component (A2) is in the above range, and thereby, the balance between the cohesive force and the tack is improved, and the adhesiveness is improved.
In the present specification, the diblock content of the component (A1) is preferably 0 to 20% by mass, and preferably 0% by mass. The linear type styrene block copolymer having a diblock content of 0% by mass is referred to as a triblock type styrene block copolymer.
The "diblock content" means the ratio of the styrene-conjugated diene compound block copolymer of formula (2) contained in a certain type of block copolymer.
The diblock content of the component (A2) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and desirably 0% by mass.
In the hot melt adhesive of the present invention, the diblock contents of the component (A1) and the component (A2) are in the above ranges, and thereby, the balance between the cohesive force and the tack becomes better, resulting in excellent adhesiveness.
The weight-average molecular weight of the component (A1) is preferably 50,000 to 150,000, particularly preferably 50,000 to 120,000, and particularly preferably 70,000 to 100,000. In the hot melt adhesive of the present invention, the weight-average molecular weight of the component (A1) is in the above range, and thereby, the cohesive force is increased, and the creep resistance and the adhesiveness are more improved while having the balance between the tack and the cohesive force.
The weight-average molecular weight of the component (A2) is preferably 80,000 to 500,000, particularly preferably 100,000 to 300,000, and particularly preferably 120,000 to 200,000. In the hot melt adhesive of the present invention, the weight-average molecular weight of the component (A2) is in the above range, and thereby the tack is increased, and the creep resistance and the adhesiveness are more improved, while having the balance between the tack and the cohesive force.
The weight-average molecular weight (Mw) means a value measured by gel permeation chromatography (GPC). Specifically, the value can be measured using the following device and measuring method. RI manufactured by Tosoh Corporation is used as a detector. As a GPC column, TSK Gel Super HZ-M manufactured by Tosoh Corporation is used. A sample is dissolved in tetrahydrofuran, which was flowed at a flow rate of 0.35 mL/min, a measurement temperature of 40&ordm;C, and the molecular weight is converted with a calibration curve for polystyrene to find the weight-average molecular weight.
Since the number average molecular weight (Mn) is also obtained by the same method, the molecular weight distribution is also calculated by GPC. Not only the component (A1) but also the Mw, Mn, and molecular weight distributions of other components can be obtained by the same method.
The component (A1) and the component (A2) are preferably linear styrene block copolymers, and particularly preferably triblock styrene isoprene block copolymers. In the hot melt adhesive of the present invention, the structures of the component (A1) and the component (A2) are linear type, and thereby, it is able to bond and keep more strongly an elastic material such as a rubber thread to a material such as a film or a non-woven fabric for disposable products.
Commercially available products may be used as the component (A1). Examples of the commercially available product include GP5562U (trade name) manufactured by LCY Chemical Corporation, VECTOR 4411AS (trade name) manufactured by TSRC Corporation, Kraton D1162PT (trade name) manufactured by Kraton Corporation, and Quintac 3191 (trade name) manufactured by Zeon Corporation.
The component (A2) may be a linear type styrene isoprene block copolymer or a radial type styrene isoprene block copolymer. In the hot melt adhesive of the present invention, the component (A2) contains a linear type styrene isoprene block copolymer, so that the tack is improved, and the adhesiveness is more improved while maintaining the balance between the cohesive force and the tack.
Commercially available products may be used as the component (A2). For example, JH8291 (trade name) manufactured by Jinhai Chemical Corporation, Quintac 3280 (trade name), Quintac 3450 (trade name), manufactured by Zeon Corporation, and VECTOR 4111 (trade name) manufactured by TSRC Corporation are cited.
In the present invention, the component (A) may contain (A3) other styrene block copolymers (not corresponding to the component (A1) or the component (A2)).
In the hot melt adhesive of the present invention, the component (A1) is contained in an amount of preferably 5 to 40 parts by mass, more preferably 10 to 25 parts by mass, and more preferably 13 to 22 parts by mass based on 100 parts by mass of the total amount of the components (A), (B) and (C). The content of the component (A1) is in the above range, and thereby, the cohesive force of the hot melt adhesive is more improved, and the creep resistance is improved.
In the hot melt adhesive of the present invention, the component (A2) is contained in an amount of preferably 0.5 to 20 parts by mass, more preferably 2 to 10 parts by mass, and further preferably 3 to 9 parts by mass, based on 100 parts by mass of the total amount of the components (A), (B) and (C). The content of the component (A2) is in the above range, and thereby, the tack of the hot melt adhesive is more improved, and the adhesive strength is improved.
<(B) Tackifying Resin>
The hot melt adhesive of the present invention contains (B) a tackifying resin. (B) The tackifying resin is not particularly limited as long as the object of the present invention is achieved as an additive for the hot melt adhesive, but it is desirable that it is a hydrogenated resin.
As (B) the tackifying resin, for example, natural rosins, modified rosins, hydrogenated rosins, glycerol esters of natural rosins, glycerol esters of modified rosins, pentaerythritol esters of natural rosins, pentaerythritol esters of modified rosins, pentaerythritol esters of hydrogenated rosins, copolymers of natural terpenes, three-dimensional polymers of natural terpenes, hydrogenated derivatives of copolymers of hydrogenated terpenes, polyterpene resins, hydrogenated derivatives of phenolic modified terpene resins, aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petroleum hydrocarbon resins, alicyclic petroleum hydrocarbon resins, hydrogenated derivatives of alicyclic petroleum hydrocarbon resins and the like may be exemplified.
These tackifying resins may be used alone or in combination. As the tackifying resin, a liquid type tackifying resin may also be used as long as the color tone is colorless to pale yellow, there is substantially no odor, and the compatibility with other components is good. Considering these characteristics comprehensively, hydrogenated derivatives of petroleum hydrocarbon resins are preferred as the tackifying resin, and hydrogenated dicyclopentadiene-based resins are particularly preferred.
In the present invention, the commercially available products of (B) the tackifying resin include T-Rez HA103 (trade name), T-Rez HB125 (trade name), T-Rez HC103 (trade name) manufactured by JXTG, HD1120 (trade name), HD1100 (trade name) manufactured by Zibo Luhua Hongjin New Material Corporation, ECR5600 (trade name) manufactured by Exxon Mobil Corporation, Eastotac H130 (trade name), Plastolyn 290LV (trade name) manufactured by Eastman Corporation, SUKOREZ SU420 (trade name), SUKOREZ SU400 (trade name) manufactured by Kolon Industries, Inc. Imarv S100 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Alcon M100 (trade name), Alcon P115 (trade name) manufactured by Arakawa Chemical Industries, Ltd. and the like.
In the hot melt adhesive of the present invention, (B) the tackifying resin is contained in an amount of preferably 40 to 70 parts by mass, and more preferably 45 to 65 parts by mass based on 100 parts by mass of the total amount of the components (A), (B) and (C).
By including (B) the tackifying resin in the above range, the hot melt adhesive of the present invention has a better balance between the cohesive force and the tack.
<(C) Plasticizer>
The hot melt adhesive of the present invention preferably contains (C) a plasticizer in addition to the component (A) and the component (B). The plasticizer is formulated for the purpose of lowering the melt viscosity of the hot melt adhesive, imparting flexibility thereof, and improving the wetting to the adherend, thereby improving the coatability of the hot melt adhesive.
(C) The plasticizer may include, for example, a paraffinic oil, a naphthenic oil and an aromatic oil.
Commercially available products may be used as the plasticizer. For example, White Oil Broom 350 (trade name) manufactured by Kukdong Oil & Chemical Co., Ltd, Diana Fresia S32 (trade name), Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Enerper M1930 (trade name) manufactured by BP Chemicals Ltd., Kaydol (trade name) manufactured by Crompton Corporation, Primol 352 (trade name) manufactured by ESSO CORPORATION, Process Oil NS100 manufactured by Idemitsu Kosan Co., Ltd., and KN4010 (trade name) manufactured by Petro China Company Limited may be exemplified. These plasticizers may be used alone or in combination.
In the hot melt adhesive of the present invention, (C) the plasticizer is contained in an amount of preferably 10 to 30 parts by mass, and more preferably 15 to 25 parts by mass, based on 100 parts by mass of the total amount of the components (A), (B) and (C).
By including (C) the plasticizer in the above range, the hot melt adhesive of the present invention has a reduced melt viscosity, and suitable low temperature coatability.
The hot melt adhesive according to the present invention may further contain various additives as necessary. As such various additives, for example, stabilizers and fine particle fillers may be exemplified.
The stabilizer is formulated in order to improve the stability of the hot melt adhesive by preventing the decrease in molecular weight, gelation, coloring, generation of odor and the like of the hot melt adhesive due to heat. It is not particularly limited as long as the intended hot melt adhesive of the present invention may be obtained. For example, antioxidants and ultraviolet absorbers may be exemplified as the "stabilizer".
The ultraviolet absorbers are used to improve the light resistance of hot melt adhesives. The "antioxidants" are used to prevent oxidative deterioration of hot melt adhesives. The antioxidants and ultraviolet absorbers may be used without being particularly limited as long as they are generally used for disposable products, and the intended disposable products described below may be obtained.
As the antioxidants, for example, phenolic antioxidants, sulfur antioxidants, and phosphoric antioxidants may be exemplified. As the ultraviolet absorbers, for example, benzotriazole-type ultraviolet absorbers and benzophenone-type ultraviolet absorbers may be exemplified. Furthermore, lactone-based stabilizers may be added. These may be used alone or in combination.
Commercially available products may be used as the stabilizer. For example, SUMILIZER GM (trade name), SUMILIZER TPD (trade name) and SUMILIZER TPS (trade name) manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, Irganox 1010 (trade name), Irganox HP2225FF (trade name), Irgafos 168 (trade name) and Irganox 1520 (trade name) manufactured by Ciba Specialty Chemicals Co., and JF77 (trade name) manufactured by JOHOKU CHEMICAL CO., LTD. may be exemplified. These stabilizers may be used alone or in combination.
The hot melt adhesive of the present invention is produced by formulating the above components in a predetermined ratio, further formulating various additives as necessary, heating, melting and mixing them. Specifically, it is produced by putting the above-mentioned components into a melting and mixing kettle equipped with a stirrer, and heating and mixing them.
The obtained hot melt adhesive has a softening point of preferably 85&ordm;C or more, more preferably 90&ordm;C or more, and still more preferably 95&ordm;C or more. The hot melt adhesive of the present invention has a softening point in the above range, resulting in excellent creep resistance.
The "softening point" is measured by the ring and ball method (the method described in the Japan Adhesive Industry Association standard JAI-7-1999).
The obtained hot melt adhesive has a melt viscosity at 140°C of preferably less than 7,000 mPa second, more preferably less than 6,500 mPa second, and further preferably less than 6000 mPa second. The hot-melt adhesive of the present invention has a melt viscosity in the above range, resulting in excellent low temperature coatability.
The "melt viscosity" means the viscosity of the melt of the hot melt adhesive. It is measured with a Brookfield RVT viscometer (spindle No. 27).
Further, in the hot melt adhesive according to the present invention, in the creep resistance evaluation method described in Examples, the strain in the dynamic viscoelasticity measurement is preferably less than 8%, and more preferably less than 5%. In the hot melt adhesive, when the strain is less than 8%, by bonding and keeping the stretched rubber thread, a material with no elasticity is able to stretch and shrink, which is suitable for use in disposable products.
The hot melt adhesive according to the present invention is widely used for paper processing, bookbinding, disposable products and the like, but is mainly used for disposable products. The "disposable product" is not particularly limited as long as it is a so-called sanitary material, for example. As the sanitary material, disposable diapers, sanitary napkins, pet sheets, hospital gowns, and surgical lab coats and the like may be specifically exemplified.
The hot melt adhesive of the present invention is preferably used for the purpose of bonding a stretched elastic material to a product body when manufacturing the disposable product in which the elastic material is incorporated.
In another gist of the present invention, there is provided a disposable product obtained by applying the above-mentioned hot melt adhesive. The disposable product is composed by bonding at least one member selected from the group consisting of woven fabric, non-woven fabric, rubber, resin and paper, and a polyolefin film, using the hot melt adhesive according to the present invention. The polyolefin film is preferably a polyethylene film because of its durability and cost.
In a disposable product manufacturing line, a hot melt adhesive is generally applied to at least one of various members (for example, non-woven fabric and the like) of a disposable product and a polyolefin film, and the film and the member are pressure bonded to manufacture a disposable product. At the time of application, the hot melt adhesive may be squirted from various squirts and used.
In the present invention, the coating may be either contact coating or non-contact coating.
"Contact coating" is a coating method in which an ejector is brought into contact with a member or a film when applying a hot melt adhesive. Specifically, V-slit coating is cited.
"Non-contact coating" is a coating method in which the ejector is not brought into contact with a member or a film when applying a hot melt adhesive. For example, spiral coating that may be applied in a spiral shape, omega coating and control seam coating that may be applied in a wavy shape, slot spray coating and curtain spray coating that may be applied in a planar shape, dot coating that may be applied in a dot form and the like may be exemplified as specific non-contact coating methods.
Examples
Hereinafter, the present invention will be described more specifically and in more detail with reference to Examples and Comparative Examples, but these Examples are merely one aspect of the present invention, and the present invention is not limited by these examples. In the description of the examples, unless otherwise specified, the portion that does not consider the solvent is used as a reference for parts by mass and % by mass.
The components used in the present examples are shown below.
(A) Thermoplastic block copolymer
(A1) Styrene isoprene block copolymer having a styrene content of more than 40% by mass
(A1-1) Linear type styrene isoprene block copolymer (GP 5562U (trade name), styrene content 45% by mass, diblock content 0% by mass (triblock content 100% by mass), weight-average molecular weight 94600, manufactured by LCY Chemical Corporation)
(A1-2) Linear type styrene isoprene block copolymer (Vector 4411AS (trade name), styrene content 44% by mass, diblock content 0% by mass (triblock content 100% by mass), weight-average molecular weight 95100,manufactured by TSRC Corporation)
(A1-3) Linear styrene-butadiene block copolymer (Kraton 1162PT (trade name), styrene content 41% by mass, diblock content 0% by mass, weight-average molecular weight 96100, manufactured by Kraton Corporation)
(A2) Styrene isoprene block copolymer having a styrene content of more than 15% by mass and less than 30% by mass.
(A2-1) Linear type styrene isoprene block copolymer (JH 8291 (trade name), styrene content 29% by mass, diblock content 0% by mass (triblock content 100% by mass), weight-average molecular weight 134000, manufactured by Jinhai Chemical Corporation)
(A2-2) Linear type styrene isoprene block copolymer (Quintac 3280 (trade name), styrene content 25% by mass, diblock content 17% by mass, weight-average molecular weight 125000, manufactured by Zeon Corporation)
(A2-3) Linear type styrene isoprene block copolymer (Vector 4111 (trade name), styrene content 18% by mass, diblock content 0% by mass (triblock content 100% by mass), weight-average molecular weight 175000, manufactured by TSRC Corporation)
(A2-4) Radial type styrene isoprene block copolymer (Quintac 3450 (trade name), styrene content 19% by mass, diblock content 30% by mass, weight-average molecular weight 194000, manufactured by Zeon Corporation)
(A3) Styrene block copolymer that does not correspond to component (A1) or component (A2)
(A3-1) Linear type styrene butadiene block copolymer (Asaprene T439 (trade name), styrene content 43% by mass, diblock content 60% by mass, weight-average molecular weight 71000, manufactured by Asahi Kasei Chemicals Corporation)
(A3-2) Linear type styrene butadiene block copolymer (GP 3566 (trade name), styrene content 30% by mass, diblock content 10% by mass, weight-average molecular weight 112000, manufactured by LCY Chemical Corporation)
(A3-3) Linear type styrene-ethylene-butadiene-styrene block copolymer (Kraton 1726MS (trade name), styrene content 30% by mass, diblock content 70% by mass, weight-average molecular weight 44000, manufactured by Craton Corporation)
(A3-4) Linear type styrene butadiene block copolymer (GP 3566 (trade name), styrene content 23% by mass, diblock content 77% by mass, weight-average molecular weight 106000, manufactured by LCY Chemical Corporation)
(B) Tackifying resin
(B1) Hydrogenated dicyclopentadiene resin (HD1100 (trade name), softening point 100°C, manufactured by Zibo Luhua Hongjin New Material Corporation)
(B2) Hydrogenated dicyclopentadiene resin (HD1120 (trade name), softening point 120°C, manufactured by Zibo Luhua Hongjin New Material Corporation)
(B3) Hydrogenated dicyclopentadiene resin (Imarv S100 (trade name), softening point 100°C, manufactured by Idemitsu Kosan Co., Ltd.)
(C) Plasticizer
(C1) Naphthenic oil ("KN 4010" (trade name)), manufactured by Petro China Company Limited)
(D) Antioxidant
(D1) Phenolic antioxidant (Irganox 1010, manufactured by BASF Corporation))
(D2) Phosphoric acid-based antioxidant (Everfos 168 GF), manufactured by Ever Spring Chemical Co., Ltd.))
Preparation of hot melt adhesives of Examples and Comparative Examples
The above-mentioned components (A) to (D) were formulated in the ratios shown in Table 1, and melted and mixed at about 150&ordm;C for 2 hours using a universal stirrer to prepare hot melt adhesives of Examples and Comparative Examples. Numerical values relating to the compositions (formulations) of the hot melt adhesives shown in the table are all parts by mass.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
With respect to the hot melt adhesives of Examples and Comparative Examples thus obtained, the softening point, melt viscosity (low temperature coatability), peel strength, loop tack, retention force, and creep resistance were examined. The evaluation results are shown in the tables. The above characteristics were evaluated by the following method.
<Softening point (heat resistance)>
The softening point of the hot melt adhesive was measured by the ring and ball method (the method described in the Japan Adhesive Industry Association Standard JAI-7-1999).
The evaluation criteria are shown below.
A (Excellent): Softening point is 95°C or more
B (Good): Softening point is 90°C or more and less than 95°C
C (Fair): Softening point is 85°C or more and less than 90°C
D (Fail): Softening point is less than 85°C
<Melt viscosity> (Low temperature coatability)>
The hot melt adhesive was heated and melted at 140°C, and the viscosity was measured with a No. 27 rotor using a Brookfield RVT viscometer.
The evaluation criteria are shown below.
A (Excellent): Melt viscosity at 140°C is less than 6000 mPa second
B (Good): Melt viscosity at 140°C is 6000 mPa second or more and less than 6500 mPa second
C (Fair): Melt viscosity at 140°C is 6500 mPa second or more and less than 7000 mPa second
D (Fail): Melt viscosity at 140°C is 7000 mPa second or more
<Peel strength (adhesiveness)>
A hot melt adhesive was applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm to prepare an adhesive layer having a thickness of 50 μm. This was formed to have a width of 25 mm, and it served as a test piece. This test piece was applied to a polyethylene film having a thickness of 100 μm at room temperature. When pasting them together, a roller weighing 2 kg was brought into contact with the PET film at a speed of 5 mm/sec. After leaving the test piece to stand at room temperature for 12 hours, it was peeled off in the 180° direction under the conditions of 25°C and a tensile speed of 300 mm/min., and the strength at which the test piece was peeled from the polyethylene (PE) film was measured. The evaluation criteria are as follows.
A (Excellent): Peel strength is 1500 (g/25 mm) or more
B (Good): Peel strength is 1200 (g/25 mm) or more and less than 1500 (g/25 mm)
C (Fair): Peel strength is 1000 (g/25 mm) or more and less than 1200 (g/25 mm)
D (Fail): Peel strength is less than 1000 (g/25 mm)
<Loop tack (adhesive strength)>
A hot melt adhesive was applied to a PET film having a thickness of 50 μm so as to have a thickness of 50 μm.
This PET film was cut into a size of 25 mm × 145 mm to produce a sample. This sample was wound in a loop shape so that the pressure-sensitive adhesive surface (adhesive-applied surface) was on the outside, and this was brought into contact with the PE plate at a speed of 300 mm/min at 30°C. After that, the test piece was peeled from the PE plate at a speed of 300 mm/min, and the peeling strength at that time was measured, and this was used as a loop tack. The evaluation criteria are shown below.
A (Excellent): Loop tack is 2500 (g/25 mm) or more
B (Good): Loop tack is 2000 (g/25 mm) or more and less than 2500 (g/25 mm)
C (Fair): Loop tack is 1500 (g/25 mm) or more and less than 2000 (g/25 mm)
D (Fail): Loop tack is less than 1500 (g/25 mm)
<Retention force (cohesive force)>
A hot melt adhesive was applied to a 50 μm-thick PET film so as to have a thickness of 50 μm. This PET film was formed, and served as a test piece (1.0 cm x 5.0 cm).
This test piece was applied to a polyethylene film having a thickness of 100 μm so that the bonded area was 1.0 cm × 1.0 cm, and then they were pressure bonded at 40°C and 0.2 MPa for 3 seconds, followed by being left at 20°C for 12 hours. After being left to stand, a load was applied vertically with a 1 kg weight in an atmosphere of 40°C, and the time until the weight fell was measured, and this was used as the retention force.
The evaluation criteria are shown below.
A (Excellent): Retention force is 300 minutes or more
B (Good): Retention force is 200 minutes or more and less than 300 minutes
C (Fair): Retention force is 150 minutes or more and less than 200 minutes
D (Fail): Retention force is less than 150 minutes
<Creep resistance>
The dynamic viscoelasticity of the hot melt adhesive was measured using a dynamic viscoelasticity measuring device (Reometer AR-G2 (trade name) manufactured by TA Instruments LLC), and the creep resistance was evaluated. The specific method is as follows.
The hot melt adhesive was heated with a measuring device jig to obtain a cylindrical molded body having a diameter of 8 mm and a thickness of 2000 μm.
This test piece was sandwiched between stainless steel parallel plates, a constant frequency of 1.0 Hz was applied at 40°C, and oscillation measurement was performed. Then, a torque of 100 μN&middot;m was applied to the test piece, strain (%) after 120 seconds was found, and creep resistance was evaluated. The evaluation criteria are shown below.
A (Excellent): Strain is less than 5%
B (Good): Strain is 5% or more and less than 6
C (Fair): Strain is 6% or more and less than 8%
D (Fail): Strain is 8% or more
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
As shown in the table, the hot melt adhesives of the examples have an excellent balance of coatability, peel strength, loop tack, retention force, creep resistance, and particularly have extremely excellent performance in creep resistance. The hot melt adhesives of the comparative examples are evaluated as D (Fail) in any of the coatability, peel strength, loop tack, retention force, and creep resistance.
It was verified from these evaluation results that, since the hot melt adhesive of the invention of the present application has an excellent balance of coatability, peel strength, loop tack, retention force, creep resistance, and particularly has extremely excellent performance in creep resistance, it is suitable for keeping the elastic material to the disposable product.
The present invention provides a hot melt adhesive and a disposable product obtained by applying the hot melt adhesive. The hot melt adhesive according to the present invention is suitable for manufacturing disposable products, and is particularly able to keep an elastic material to a disposable product.

Claims (6)

  1. A hot melt adhesive comprising (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, (B) a tackifying resin, and (C) a plasticizer, wherein
    (A) the thermoplastic block copolymer comprises the following component (A1) and component (A2):
    (A1) a styrene isoprene block copolymer having a styrene content of more than 40% by mass; and
    (A2) a styrene isoprene block copolymer having a styrene content of more than 15% by mass and less than 30% by mass.
  2. The hot melt adhesive according to claim 1, wherein the component (A1) has a weight-average molecular weight of 50,000 to 150,000.
  3. The hot melt adhesive according to claim 1 or 2, wherein the component (A1) is contained in an amount of 10 to 25 parts by mass, and the component (A2) is contained in an amount of 2 to 10 parts by mass, based on 100 parts by mass of the total of the components (A) to (C).
  4. The hot melt adhesive according to any one of claims 1 to 3, wherein (B) the tackifying resin is contained in an amount of 45 to 70 parts by mass, based on 100 parts by mass of the total of the components (A) to (C).
  5. The hot melt adhesive according to any one of claims 1 to 4, for use in fixing an elastic material to a disposable product body.
  6. A disposable product to which the hot melt adhesive according to any one of claims 1 to 5 is applied.
PCT/JP2022/031202 2021-08-19 2022-08-18 Hot melt adhesive WO2023022193A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016044289A (en) 2014-08-26 2016-04-04 ヘンケルジャパン株式会社 Hot melt adhesive
JP2016153448A (en) 2015-02-20 2016-08-25 ヘンケルジャパン株式会社 Hot-melt adhesive and disposable product
EP3081611A1 (en) * 2013-12-11 2016-10-19 Nichiban Co. Ltd. Self-adhesion-type adhesive tape
WO2020110921A1 (en) 2018-11-28 2020-06-04 積水フーラー株式会社 Hot melt composition

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3081611A1 (en) * 2013-12-11 2016-10-19 Nichiban Co. Ltd. Self-adhesion-type adhesive tape
JP2016044289A (en) 2014-08-26 2016-04-04 ヘンケルジャパン株式会社 Hot melt adhesive
JP2016153448A (en) 2015-02-20 2016-08-25 ヘンケルジャパン株式会社 Hot-melt adhesive and disposable product
EP3259327A1 (en) * 2015-02-20 2017-12-27 Henkel AG & Co. KGaA Hot melt adhesive and disposable product
WO2020110921A1 (en) 2018-11-28 2020-06-04 積水フーラー株式会社 Hot melt composition

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