JP7215864B2 - Adhesive composition, laminate and packaging material using adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition, a laminate and a packaging material using the pressure-sensitive adhesive composition.

A heat-shrinkable film is known as a shrink film. For example, when an object to be wrapped is heated to a predetermined temperature, it shrinks in a short period of time and adheres tightly to the object to be wrapped to form a package with a good appearance. can be formed.
In recent years, it has been studied to laminate a non-woven fabric to a heat-shrinkable film to improve the design and feel, as well as to improve the strength of the heat-shrinkable film itself and to add mechanical properties such as preventing damage to the packaged object. (See Patent Documents 1 to 3, for example).

JP 2007-76259 A JP 2015-55791 A JP 2005-70739 A

However, when a heat-shrinkable film and a non-woven fabric are bonded together, the non-woven fabric itself is heat-shrinkable, but the shrinkage is different from that of the heat-shrinkable film. Therefore, even if the nonwoven fabric or the heat-shrinkable film is bonded together at normal temperature using an adhesive that can adhere to the heat-shrinkable film, or the two are bonded together by thermocompression, when the heat-shrinkable film and the non-woven fabric are thermally shrunk, Delamination may occur and the surface of these laminates may wrinkle. In particular, when a heat-shrinkable film and a non-woven fabric are continuously bonded together by thermocompression using a thermoplastic resin type adhesive, it is necessary to perform thermocompression bonding with a heating roll or the like. The shrink film and the non-woven fabric cannot be strongly thermo-compressed. In addition, if the heating temperature is increased, the heat-shrinkable film will shrink, making it difficult to bond the films continuously by thermocompression.
The present application has been made in order to solve the above-mentioned problems. An object of the present invention is to provide a pressure-sensitive adhesive composition that can effectively prevent delamination between a heat-shrinkable film and a non-woven fabric, generation of wrinkles on the surface, etc., and a laminate and a packaging material using the same.

The present application provides the following inventions.
(1) A pressure-sensitive adhesive composition for bonding a heat-shrinkable film and a nonwoven fabric,
The dried and cured adhesive composition has a glass transition temperature (Tg) of −70° C. to −10° C., a toluene insoluble content (TIP) of 2% by mass or more, and a melting point of 0° C. or less or amorphous. A pressure-sensitive adhesive composition characterized by having no melting point at .
(2) The pressure-sensitive adhesive composition according to (1), which contains an acrylic resin and a cross-linking agent.
(3) The adhesive composition according to (1) or (2), wherein the TIP is 53% by mass or less.
(4) having an adhesive layer between the heat-shrinkable film and the nonwoven fabric;
The adhesive layer has a glass transition temperature (Tg) of −70° C. to −10° C., a toluene insoluble content (TIP) of 2% by mass or more, and a melting point of 0° C. or less, or is amorphous and has no melting point. A laminate characterized by:
(5) The laminate according to (4), which exhibits a shrinkage rate of 5% or more in at least one direction under heat load at 150° C. for 10 seconds.
(6) The laminate according to (4) or (5), wherein the pressure-sensitive adhesive layer contains an acrylic resin and a cross-linking agent.
(7) A packaging material comprising the laminate according to any one of (4) to (6) above.

According to the present application, the adhesiveness between the heat-shrinkable film and the nonwoven fabric can be ensured even after heat shrinkage, and the delamination between the heat-shrinkable film and the nonwoven fabric, the occurrence of wrinkles on the surface, and the like can be reliably prevented. . As a result, when the object to be wrapped is covered and brought into close contact with the object by thermal shrinkage, good shrinkage can be given to ensure close contact with the object to be packaged.

[Adhesive composition]
The pressure-sensitive adhesive composition in the present application is particularly effective for bonding a heat-shrinkable film and a nonwoven fabric, and can bond the two together at room temperature or low temperature, for example, 50° C. or less, and exhibits good adhesion. It is something that can be secured. As a result, a laminate in which the heat-shrinkable film and the nonwoven fabric are bonded together can be continuously manufactured by strong bonding. In addition, since it is not necessary to perform thermocompression bonding through a heating roll to bond the heat-shrinkable film and the non-woven fabric as in the conventional method, the heat-shrinkable film can be thermally shrunk at the time of bonding. Therefore, the laminate can be manufactured simply and with high quality. In addition, even when the heat-shrinkable film and the non-woven fabric are bonded together, the laminated body is heat-shrunk, ensuring strong adhesion and reliably preventing the delamination of the heat-shrinkable film and the non-woven fabric and the occurrence of wrinkles on the surface. can do. As a result, when an object to be packaged is covered with a laminate using the pressure-sensitive adhesive composition of the present application and adhered to the object by heat shrinkage, moderate and good shrinkage is applied to improve adhesion to the object to be packaged. can be secured.

Since the pressure-sensitive adhesive composition in the present application heat-shrinks a laminate obtained by laminating a heat-shrinkable film and a non-woven fabric, it has heat resistance.
The pressure-sensitive adhesive composition in the present application is suitable to be a two-liquid curing type in order to control performance in consideration of adhesion during lamination and heat resistance during use.
In order to ensure both adhesiveness and heat resistance, the pressure-sensitive adhesive composition in the present application may have, for example, a glass transition temperature (Tg) of -70°C to -10°C for a dried and cured product of the pressure-sensitive adhesive composition. Preferably, -50°C to -20°C is more preferred. In order to ensure heat resistance, the pressure-sensitive adhesive composition in the present application preferably has a toluene-insoluble content (TIP) of 2% by mass or more, for example. Moreover, it is preferable that it is 53 mass % or less. In particular, 5% to 53% by mass is more preferable, 8% to 53% by mass is more preferable, 10% to 53% by mass is even more preferable, and 10% to 49% by mass is particularly preferable. In addition, the pressure-sensitive adhesive composition in the present application preferably has a melting point of 0° C. or lower or is amorphous and has no melting point, in order to ensure adhesion during bonding at room temperature, and is amorphous and has no melting point. is more preferred. Regarding the melting point, whether or not a melting peak was observed, and if it was observed, the peak area, that is, the apex of the crystal melting peak at which the heat of crystal melting was 1 J/g or more was taken as the melting point. The crystal melting peak can be measured, for example, by the method described in Examples below.
Here, Tg, toluene-insoluble matter and melting point are the values measured by the methods described in Examples.

In general, if the PSA composition is amorphous, the glass transition temperature is low, and if the molecular weight is low, the adhesiveness is high, but the heat resistance is not good. It tends to have higher heat resistance and lower adhesiveness. In addition, when a melting point exists, adhesiveness is exhibited above the melting point. Therefore, by adjusting the glass transition temperature, molecular weight and melting point described above, it is possible to achieve a balance between adhesiveness and heat resistance. The glass transition temperature and melting point of the dried and cured adhesive composition can be adjusted by the resin composition and the like. The toluene-insoluble matter in the dried and cured product of the pressure-sensitive adhesive composition can be obtained, for example, by selecting the type and/or amount of a chain transfer agent that is a molecular weight modifier when polymerizing the main component resin that constitutes the pressure-sensitive adhesive composition. can be adjusted by increasing or decreasing the molecular weight. In addition, the toluene-insoluble content is selected by blending two or more resins with different toluene-insoluble content, setting the amount of polymerization initiator during polymerization of the resin, the polymerization initiation temperature, etc., and the type and amount of the cross-linking agent to be contained. It can also be adjusted by As the chain transfer agent, any of known ones may be used, but when methyl bromide or α-methylstyrene dimer, which is a halogen compound, is used, the amount used is based on the total mass of the monomers used. 10% by mass or less, and when mercaptans such as t-dodecylmercaptan, n-dodecylmercaptan, octylmercaptan and nonylmercaptan are used, the amount used can be 5% by mass or less. In particular, the toluene-insoluble content is preferably adjusted to 2 to 53% by mass when a laminate obtained by laminating a heat-shrinkable film and a nonwoven fabric is to be fused by an automatic packaging machine. If you want to cut with, it is more preferable to adjust to 2 to 49% by mass.
By setting the toluene-insoluble content of the cured product of the adhesive composition within this range, it is possible to effectively prevent delamination between the heat-shrinkable film and the nonwoven fabric when the laminate is thermally shrunk, and the adhesive composition The cured product can be made to have an appropriate hardness, and deterioration of adhesion to heat-shrinkable films and nonwoven fabrics can be prevented. As a result, for example, when an object to be packaged is packaged with this laminate using an automatic packaging machine or the like, the laminate can be easily thermally fused, and the packaging efficiency as a packaging material can be secured or improved. can.

(resin)
Various resins can be used as the main component of the pressure-sensitive adhesive composition. Among them, it is preferable to use a thermoplastic resin having a melting point of 0° C. or lower or an amorphous resin having no melting point. For example, ethylene-vinyl ester resins, styrene-maleic acid resins, resins having a structural unit derived from an α-olefin having 2 to 20 carbon atoms, chlorinated products and modified products thereof, (meth)acrylic resins, polystyrene, polyvinyl acetate , polyurethane, polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic acid ester copolymer resin, vinyl chloride-vinylidene chloride copolymer resin, vinylidene chloride-(meth ) acrylic ester copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, resin having a chlorinated α-olefin-derived structural unit having 2 to 20 carbon atoms, ethylene-vinyl ester resin, polyurea, acrylonitrile butadiene styrene resin, Chloroprene resin, acid-modified chloroprene resin, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, modified rubber, styrene-(meth)acrylic acid resin, synthetic rubber, natural rubber, styrene-butadiene resin, butadiene resin, poly(meth)acrylonitrile Resins, (meth)acrylamide resins, polyester resins, modified nylon resins, epoxy resins, styrenic block copolymers, oligomers thereof, and the like. These may be used singly or in combination. Among them, those containing an acrylic resin as a main component resin are preferable. The resin as the main component means one that accounts for 50% by mass or more of the non-volatile content of the pressure-sensitive adhesive composition.

The acrylic resin may be a copolymer of an acrylic monomer, or a copolymer of an acrylic monomer and a monomer copolymerizable with the acrylic monomer.
Examples of acrylic monomers include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl acrylate, n-butyl (meth) acrylate, acrylic acid Isobutyl, t-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid normal octyl, decyl (meth) acrylate, octadecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and other (meth) acrylic acid alkyl esters, cyclohexyl (meth) acrylate, (meth) ) Benzyl acrylate, phenyl (meth)acrylate and other (meth)acrylic acid cyclic esters, allyl (meth)acrylate, 1-methylallyl (meth)acrylate, 2-methylallyl (meth)acrylate and other (meth) ) Unsaturated group-containing (meth)acrylic acid esters such as vinyl acrylate, heterocyclic ring-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate , amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate, N-tributylaminoethyl (meth)acrylate, and N,N-dimethylaminoethyl (meth)acrylate, 3 - Alkoxysilyl group-containing (meth)acrylic acid esters such as methacryloxypropyltrimethoxysilane, methoxyethyl (meth)acrylate, (meth)acrylic acid derivatives such as ethylene oxide adducts of (meth)acrylic acid, ( Perfluoroalkyl (meth)acrylates such as perfluoroethyl methacrylate and perfluorobutyl (meth)acrylate, polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, etc. and copolymers derived from the monomers.
These monomers are preferably copolymerized by adding a monomer into which a carboxylic acid group or a hydroxyl group or the like has been introduced in order to react with the functional group of the cross-linking agent described later.

Monomers copolymerizable with acrylic monomers include maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride as monomers having at least one carboxyl group in the radically polymerizable unsaturated group. Further, as monomers having at least one hydroxyl group in addition to the radically polymerizable unsaturated group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, diethylene glycol mono (Meth)acrylate and the like. Furthermore, vinyl monomers copolymerizable with acrylic monomers include, for example, aromatic vinyl monomers such as styrene and α-styrene; trialkyloxysilyl group-containing vinyl monomers such as vinyltrimethoxysilane; Nitrile group-containing vinyl monomers such as ronitrile, acrylamide and methacrylamide group-containing vinyl monomers, and vinyl esters such as vinyl acetate and vinyl versatate.
Among them, a resin obtained by copolymerizing normal butyl acrylate is preferable.
The acrylic resin preferably contains 30% by mass or more of the acrylic monomer, more preferably 50% by mass or more, and even more preferably 80% by mass.

The resin used in the adhesive composition can be obtained by radical polymerization in an organic solvent.
Organic solvents that can be used include ethyl acetate, n-butyl acetate, isobutyl acetate, acetone, and methyl ethyl ketone. These may be used alone or in combination of two or more.
It is preferable to use a polymerization catalyst in the polymerization. Polymerization catalysts include organic peroxide-based polymerization initiators such as benzoyl peroxide, di-t-butyl peroxide, and cumene hydroperoxide, and azo-based polymerization initiators such as 2,2′-azobis(2-methylbutyronitrile). A polymerization initiator and the like are included. These may be used alone or in combination of two or more.

(crosslinking agent)
The adhesive composition preferably contains a cross-linking agent. By using a cross-linking agent, the pressure-sensitive adhesive composition can be cross-linked and the toluene-insoluble content can be adjusted. As a result, cohesive strength and/or heat resistance of the pressure-sensitive adhesive composition can be improved, and peeling can be suppressed even when the heat-shrinkable film shrinks.
Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, amine-based cross-linking agents, and carbodiimide-based cross-linking agents. These cross-linking agents may be used alone or in combination of two or more.
Examples of isocyanate-based cross-linking agents include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tri Examples include diisocyanate. Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) and the like. Examples of araliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene and the like. Alicyclic polyisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) and the like.

Epoxy cross-linking agents include bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl. ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, etc. is mentioned.
The amine-based cross-linking agent may be any polyamine having two or more primary amino groups, and from the viewpoint of excellent curing speed, polyamines having two or more primary amino groups that are not directly bonded to an aromatic ring, such as Aliphatic polyamines in which primary amino groups are directly bonded to aliphatic functional groups or alicyclic functional groups are preferred. Aliphatic polyamines may contain aromatic rings in their skeleton, provided that the aromatic rings are not directly bonded to primary amino groups.

The carbodiimide compound is preferably a compound having two or more carbodiimide groups (-N=C=N-) in the molecule, and known polycarbodiimides can be used. As the carbodiimide compound, a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidation catalyst can also be used. Examples of such compounds include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction. Diisocyanates include 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'- dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferred because they react at low temperature curing.
The amount of these cross-linking agents to be added is preferably adjusted so that the toluene-insoluble content of the dried and cured product of the pressure-sensitive adhesive composition falls within the range described above. For example, it is preferably 0.1 to 10 parts by weight, preferably 0.5 to 9 parts per 100 parts by weight of the non-volatile matter containing additives such as resins and tackifiers that constitute the main component of the pressure-sensitive adhesive composition. Parts by weight are more preferred, and 0.5 to 6 parts by weight is even more preferred.

(Tackifier)
Furthermore, the adhesive composition may contain a tackifier. As tackifiers, rosins, terpene-based resins, petroleum-based resins obtained by polymerizing petroleum fractions having 5 carbon atoms and hydrogenated resins thereof, petroleum-based resins obtained by polymerizing petroleum fractions having 9 carbon atoms and hydrogenated resins thereof. , other petroleum-based resins, coumarone resins and indene resins. Specifically, rosin, polymerized rosin, disproportionated rosin, hydrogenated rosin, maleated rosin, fumarated rosin and their glycerol esters, pentaerythritol esters, methyl esters, triethylene glycol esters, phenol-modified products and their esters. rosins such as compounds; terpene resins such as terpene polymers, terpene phenols, β-pinene polymers, aromatic modified terpene polymers, α-pinene polymers, terpene hydrogenated resins; petroleum fractions having 5 carbon atoms , petroleum-based resins obtained by polymerizing petroleum fractions having 9 carbon atoms, and hydrogenated resins thereof; petroleum-based resins such as maleic acid-modified products and fumaric acid-modified products, and chlorinated paraffins. These may be used alone or in combination of two or more. Among them, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone-indene resins, phenolic resins, terpene-phenolic resins, rosin derivatives (rosin, modified rosin, hydrogenated rosin, etc.) and the like are preferred.
When the pressure-sensitive adhesive composition of the present invention contains a tackifier, the content thereof is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, relative to 100 parts by mass of the main component resin, More preferably, it is 40 parts by mass or less.

(solvent)
It is preferable to use an organic solvent rather than a water-based solvent for the pressure-sensitive adhesive composition. By this, drying at a low temperature can be performed early. Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane; esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone (MIBK); alcohols such as ethanol, n-propanol, isopropyl alcohol and n-butanol; glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol; methyl cellosolve, cellosolve, butyl cellosolve, dioxane, MTBE (methyl tertiary butyl ether) and Cellosolve solvents such as butyl carbitol; glycol solvents such as diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether and 3-methoxy-3-methyl-1-butanol; ethylene glycol monomethyl ether acetate, PMA ( propylene glycol monomethyl ether acetate), diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and other glycol ester solvents; These may be used alone or in combination. Among them, toluene, ethyl acetate, methyl ethyl ketone, MIBK and the like are preferable.
When the pressure-sensitive adhesive composition of the present application contains an organic solvent, the content thereof is preferably 70 parts by mass or more with respect to 100 parts by mass of the non-volatile matter including additives including the main component resin and tackifier. It is more preferably from 200 parts by mass to 400 parts by mass, and even more preferably from 200 parts by mass to 300 parts by mass.

(other ingredients)
The pressure-sensitive adhesive composition of the present application can contain various additives as long as the object of the present invention is not impaired. For example, various additive components such as tackifying resins, weather stabilizers such as antioxidants, plasticizers, softeners, dyes, pigments, and inorganic fillers can be contained. Any known one can be used for these.

The adhesive composition has a viscosity of, for example, 50 mPa·s to 10000 mPa·s, preferably 50 mPa·s to 5000 mPa·s, more preferably 50 mPa·s to 1000 mPa·s. . Such a viscosity can be appropriately adjusted by the degree of polymerization, the amount of additives such as a cross-linking agent and a solvent, and the like. Although it varies depending on the performance of the coating machine used, it is preferable to set the viscosity of the pressure-sensitive adhesive composition at the time of use within such a range.

[Laminate]
The laminate is constructed by having an adhesive layer between the heat-shrinkable film and the nonwoven fabric. The laminate may include a printed layer for displaying characters and/or pictures, or may be laminated with a printed layer. The printed layer is the opposite side of the heat-shrinkable film to the non-woven fabric, between the heat-shrinkable film and the adhesive layer, between the adhesive layer and the non-woven fabric, and the opposite side of the non-woven fabric to the heat-shrinkable film. It can be wholly or partly located on any one or more of the faces.

(Adhesive layer)
The pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive composition described above. The thickness of the adhesive layer is, for example, 20 μm or less, preferably 2 μm to 10 μm, more preferably 2 μm to 5 μm. By setting the thickness in such a range, the heat-shrinkable film and the nonwoven fabric can be firmly adhered to each other, and delamination can be prevented even when the laminate heat-shrinks. In addition, for example, with this laminate, when an object to be packaged is packaged using an automatic packaging machine, the laminate can be easily thermally fused, and the packaging efficiency as a packaging material can be secured or improved. can be done.

(heat shrink film)
Heat shrink film refers to a film that shrinks when heated. In other words, the film is stretched at a glass transition point or higher and a melting point or lower to give molecular orientation and heat-treated, with or without cross-linking by electron beam irradiation. It is a given film. For example, when a laminate using the same is used for a label or the like, the heat-shrinkable film may be one that has heat-shrinkability in at least one direction. It is common to give In addition, when used for applications such as packaging materials, it is preferable to have heat shrinkability in the biaxial direction, and it is common to impart heat shrinkability by using a sequential biaxial stretching method by roll stretching and tenter stretching. be. Also, as the shrink wrapping film, a film specified in JIS Z 1709 may be used. Any known heat-shrinkable film can be used.

Examples of heat-shrinkable films include polyester resins such as polyethylene terephthalate; olefin resins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers; styrene resins such as polystyrene and styrene-butadiene copolymers; A film formed by combining a single or a plurality of thermoplastic resins such as resins and vinyl chloride resins can be used. Among them, the heat-shrinkable film is preferably an olefin-based resin having a melting point of 170° C. or lower when the laminate is sealed and/or melted by an automatic packaging machine. These may have a single layer structure or a laminated structure. The heat-shrinkable film may contain an antioxidant, a surfactant, a pore-forming agent, etc., in addition to the thermoplastic resin. Those known in the art can be used for these.
The heat-shrinkable film may be colored, colorless, transparent, translucent, or opaque. Among them, a transparent film is preferable.
The thickness of the heat-shrinkable film is, for example, 10 μm to 100 μm, preferably 10 μm to 50 μm.

(non-woven fabric)
The non-woven fabric in the present application is literally a sheet-like product in which fibers are entangled without weaving, the fibers are oriented in one direction or randomly, and the fibers are bonded by entangling, fusion and / or adhesion. . Examples of such nonwoven fabrics include those conforming to JIS L 0222. Nonwoven fabrics are roughly classified into short fiber nonwoven fabrics and long fiber nonwoven fabrics depending on the length of the fibers. Among them, the long-fiber nonwoven fabric is more preferable than the short-fiber nonwoven fabric in view of the strength of the nonwoven fabric and the handling of thread pull-out. The manufacturing method includes a step of forming a fiber accumulation layer and a step of bonding between fibers. A dry method, a wet method, a spunbond method, a meltblowing method, a flash spinning method and the like can be used as the fiber accumulation layer forming step. As the interfiber bonding step, one or more of a thermal bond method, a chemical bond method, a needle punch method, a spunlace method, and the like can be used in combination. Among them, it is preferable to form an integrated layer by a spunbond method, and to obtain an interfiber bonding step in which one or more are combined by a thermal bond method, a chemical bond method, a needle punch method, or the like.
If the nonwoven fabric does not follow the heat shrinkage of the heat shrinkable film, delamination will occur.
If the melting point of the fibers of the non-woven fabric is far from the shrinking temperature of the heat-shrinkable film, it will be difficult to follow. For this reason, the melting point of the nonwoven fabric fibers is preferably 200° C. or lower, more preferably 170° C. or lower.
The non-woven fabric can be made of fibers such as polyester, polyolefin such as polypropylene or polyethylene, rayon paper, nylon, and cupra. Among them, a nonwoven fabric using polyolefin fibers is preferable because it has a melting point of 170° C. or less. The polyolefin fiber may be mixed with other types of resins, or may have a core-sheath structure with other resins.

In addition, when the nonwoven fabric is hard, it does not follow the shrinkage of the heat-shrinkable film and delaminates. The hardness of the nonwoven fabric varies depending not only on the material, but also on the degree of bonding between fibers, surface treatment, and the like. For this reason, bonding between fibers by a thermal bond method, a chemical bond method, or the like is preferable because the degree of bonding between fibers can be controlled by the area of bonding points with respect to the area of the nonwoven fabric. In the thermal bonding method, the non-woven fabric is heat-sealed while pressing the web with a smooth hot roll, a method in which hot air is passed through the web in an oven to bond it, and a hot roll with an embossed pattern. There is a type that heat-seales the web while pressing it. The chemical bond method can control the application area of the adhesive composition using a plate like gravure printing. In particular, the embossing of thermal bond is easy to control and is preferably used in combination with the needle punch method. The embossed area on the nonwoven fabric surface can be observed with an optical microscope. The embossed area is preferably 50% or less, more preferably 40% or less, still more preferably 38% or less, and particularly preferably 30% or less, of the plane area of the surface of the nonwoven fabric sheet. The embossed area as used herein refers to the total area of the area pressed onto the surface of the nonwoven fabric in thermal bonding. In the case of such a range, the adhesiveness with the adhesive composition, in particular, the adhesion when a laminate with a heat-shrinkable film is formed through the adhesive layer and the laminate is shrunk by a heat load. I have confirmed that it is good.

Examples of commercially available nonwoven fabrics include Leafa manufactured by Tsujitomi, Elves manufactured by Unitika, Syntex manufactured by Mitsui Chemicals, and Libsen manufactured by Toray.
The basis weight of the nonwoven fabric is 15 g/m ² to 200 g/m ² . As the basis weight of the nonwoven fabric increases, the thickness increases, and the thickness of the pressure-sensitive adhesive composition also needs to be increased. In addition, since it takes time for the nonwoven fabric to conduct heat, a smaller basis weight is advantageous in consideration of heat shrinkability. The thickness of the pressure-sensitive adhesive layer is preferably within a range that is industrially controllable and is preferably 15 g/m ² to 120 g/m ² in consideration of heat shrinkability.
The melting point of the nonwoven fabric is 200°C or less, preferably 110°C to 180°C, more preferably 120°C to 170°C. By setting it to this range, it becomes easy to cut the laminate into a predetermined size at the time of manufacturing the laminate, and at the time of packaging the object to be packaged, for example, using an automatic packaging machine. can facilitate thermal fusion cutting of the laminate when packaging, and can ensure or improve packaging efficiency as a packaging material. Furthermore, when the object to be packaged is wrapped, the melted nonwoven fabric shrinks following the heat-shrinkable film, effectively preventing delamination between the nonwoven fabric and the heat-shrinkable film and wrinkles on the surface of the laminate. can be done.
The nonwoven fabric has a thickness of 50 μm to 600 μm, preferably 50 μm to 400 μm, more preferably 100 μm to 350 μm. The thickness of the nonwoven fabric can be measured by the method described in JIS L 1913.

(Print layer)
Printed layer, for example, JP-A-2007-76259, JP-A-5-70739, JP-A-2005-70739, JP-A-2013-189718, etc. design printed layer, it is used to form a decorative layer. Any ink or the like may be used.

によって表される。 [Method for producing laminate and packaging material]
The laminate is produced by applying the pressure-sensitive adhesive composition to either a nonwoven fabric or a heat-shrinkable film to form an adhesive layer, and bonding the nonwoven fabric and the heat-shrinkable film via the adhesive layer. can be done.
The laminate preferably exhibits a shrinkage rate of 5% or more in at least one direction, and preferably exhibits a shrinkage rate of 5% or more in each of at least two directions, when subjected to a heat load of 150° C. for 10 seconds. The shrinkage rate (%) here is

represented by

(Coating of adhesive composition)
The adhesive composition may be applied while adjusting the coating amount using an applicator, bar coater, or the like, or using a general coating machine such as a gravure roll coater, a comma coater, a knife coater, or the like. May be coated. The coating amount of the pressure-sensitive adhesive composition can be appropriately adjusted depending on the viscosity of the pressure-sensitive adhesive composition, the basis weight of the nonwoven fabric, and the like. The pressure-sensitive adhesive composition is preferably applied to the heat-shrinkable film side.
After applying the pressure-sensitive adhesive composition, using a hot air dryer or the like, the temperature is as low as possible such that the heat-shrinkable film does not shrink and the solvent of the pressure-sensitive adhesive composition can volatilize, for example, 50 ° C. or less. It is preferable to dry the pressure-sensitive adhesive composition at a temperature of while adjusting the air flow rate. The drying time can be appropriately set depending on the type of solvent of the pressure-sensitive adhesive composition, the concentration of non-volatile matter, the amount of coating, the amount of air during drying, and the like. For example, from several seconds to one hour.

(Lamination of heat-shrinkable film and non-woven fabric)
It is preferable that the heat-shrinkable film and the non-woven fabric are laminated continuously after the step of drying the pressure-sensitive adhesive layer, in order to simplify and facilitate the work. After the drying step, when the operation of forming the laminate is temporarily stopped, it is necessary to wind up the nonwoven fabric or heat-shrinkable film having the pressure-sensitive adhesive layer formed on the surface. This is because the surface of the pressure-sensitive adhesive layer becomes tacky, so that it is necessary to sandwich release paper or the like. Furthermore, when the pressure-sensitive adhesive composition contains a cross-linking agent, depending on the type of cross-linking agent, the cross-linking reaction proceeds after the pressure-sensitive adhesive layer is dried, and the initial adhesion to the material to be laminated may be reduced. It is from.
The heat-shrinkable film and the nonwoven fabric are preferably laminated together with the heat-shrinkable film and the nonwoven fabric via an adhesive layer, and are preferably performed without heating using a laminator, a hand roller, or the like. By laminating them together in this way, the nonwoven fabric and the heat-shrinkable film can be bonded together without causing delamination and wrinkles on the surface of the laminate. Alternatively, a multi-layered state in which the heat-shrinkable film and the non-woven fabric are superimposed with an adhesive layer interposed therebetween can be passed between rolls using a crimping machine to crimp. In order to prevent shrinkage of the heat-shrinkable film, it is preferable to set the temperature of the rolls to the lowest possible temperature during pressure bonding. However, when the air temperature is low, such as in winter, the initial adhesive strength of the pressure-sensitive adhesive composition decreases, so it is preferable to heat the roll to such an extent that the heat-shrinkable film does not shrink.

After laminating the heat-shrinkable film and the nonwoven fabric, it is preferable to carry out curing in order to completely harden the pressure-sensitive adhesive composition. Curing is preferably carried out at a temperature of about ±20° C. from normal temperature for several hours to several months. By such curing, the molecules of the pressure-sensitive adhesive layer can be sufficiently crosslinked, and the mechanical properties of the laminate can be enhanced.
When designing the obtained laminate as a packaging material, the design can be applied by forming a design layer in advance, arranging it at an arbitrary position, and performing the above steps. Moreover, after forming the laminate, a design layer may be arranged at an arbitrary position by pasting, coating, or the like.
In addition, when various articles are to be packaged as packaging materials, they may be cut into appropriate sizes, shapes, etc. or thermally fused. It may be laminated into an appropriate shape such as a shape, a two-dimensional or three-dimensional bag shape, or processed by using heat sealing or the like. The cutting or thermal fusion cutting here includes a method using a fusion heater, a wire/piano wire heater, or the like. Heat sealing can be performed using a hot plate sealer, an impulse sealer, an ultrasonic sealer, a band sealer, a hot air sealer, a high frequency sealer, a flame sealer, or the like.

[How to use packaging materials]
The packaging material of the present application can be used as objects to be packaged: boxes (cosmetic registers, wooden boxes for somen noodles, Japanese sweets, food boxes for canned foods, etc., building materials (decorative plywood, doors, aluminum sashes, etc.), fragile items (liquid crystal displays, Glass plates, glass bottles for sake and wine, etc.), various parts (automobile parts, home appliance parts, precision equipment parts, etc.), food (fruits, vegetables, frozen foods, processed foods such as ham and sausages), long-term storage items (sea It can be used for various purposes such as a sunken ship pulled up from the

Packaging to the object to be packaged is carried out by partially or completely covering the object to be packaged with a laminate as a packaging material, and then heating the laminate to shrink the laminate and adhere it to the object to be packaged. can be done. The heating in this case can be appropriately set depending on the material forming the laminate. For example, it is 110° C. or higher, preferably 120° C. or higher, and more preferably 130° C. or higher. The heating time is, for example, 1 second to several minutes. Examples of the heating method include known methods such as blowing hot air, immersion or application in warm water, blowing heated steam, and infrared irradiation.
By such heating, the surface of the packaging material has a good appearance such as a wrinkle-free appearance, no voids as much as possible with respect to the object to be packaged, or an appropriate margin of margin for close contact with the object to be packaged. can be given.
After shrinking the packaging material by heating, the package may optionally be cooled.

[Preparation of adhesive composition]
(Example 1)
Main agent CMX AC1002-S16 (acrylic adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 25% by mass, viscosity 100 mPa s) and cross-linking agent CMX KO1001-S17 (TDI-based polyisocyanate cross-linking agent, prototype manufactured by Sumika Chemtex, non-volatile content 37.5% by mass) were blended at a non-volatile content ratio: main agent/crosslinking agent = 100/2 to obtain an adhesive composition (viscosity 100 mPa s, Tg of dried and cured adhesive composition: -34 ° C. , TIP: 30% by weight, no melting point).
(Example 2)
The main agent CMX AC1002-S16 and the cross-linking agent CMX KO1001-S17 were blended at a non-volatile ratio: main agent/cross-linking agent = 100/3 to obtain a pressure-sensitive adhesive composition (viscosity 100 mPa s, dried and cured pressure-sensitive adhesive composition Tg: −34° C., TIP: 47% by mass, no melting point).
(Example 3)
Main agent CMX AD1001-S18 (acrylic adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 25% by mass, viscosity 660 mPa s) and cross-linking agent CMX KO1002-S18 (TDI-based polyisocyanate cross-linking agent, prototype manufactured by Sumika Chemtex, non-volatile content 46 % by mass) were blended at a nonvolatile content ratio: main agent/crosslinking agent = 100/0.5 to obtain an adhesive composition (viscosity 760 mPa s, Tg of dried and cured adhesive composition: -24 ° C., TIP: 49% by weight, no melting point).
(Example 4)
Main agent CMX AD1002-S17 (acrylic adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 25% by mass, viscosity 220 mPa s) and cross-linking agent CMX KO1003-S17 (TDI-based polyisocyanate cross-linking agent, prototype manufactured by Sumika Chemtex, non-volatile content 46 %) and non-volatile content ratio: main component/crosslinking agent = 100/1.5 to obtain a pressure-sensitive adhesive composition (viscosity 240 mPa s, Tg of dried and cured pressure-sensitive adhesive composition: -30 ° C., TIP: 47% by weight, no melting point).
(Example 5)
Base agent CMX AD1003-S19 (acrylic adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 25% by mass, viscosity 420 mPa s) and cross-linking agent CMX KO1003-S17 Non-volatile content ratio: main agent / cross-linking agent = 100/1.2 to obtain an adhesive composition (viscosity 460 mPa·s, Tg of dried and cured adhesive composition: −40° C., TIP: 48% by mass, no melting point).
(Example 6)
The main agent CMX AD1001-S18 and the cross-linking agent CMX KO1002-S18 were blended at a non-volatile ratio: main agent/cross-linking agent = 100/1 to obtain a pressure-sensitive adhesive composition (viscosity 760 mPa s, dried and cured pressure-sensitive adhesive composition Tg: −24° C., TIP: 53% by mass, no melting point).

(Comparative example 1)
A pressure-sensitive adhesive composition was prepared using only the main agent CMX AC1002-S16 (Tg of the dried and cured pressure-sensitive adhesive composition: -34°C, TIP: 0 wt%, no melting point).
(Comparative example 2)
The main agent CMX AC1002-S16 and the cross-linking agent CMX KO1001-S17 were blended at a non-volatile ratio: main agent/cross-linking agent = 100/1 to obtain a pressure-sensitive adhesive composition (viscosity 100 mPa s, dry-cured pressure-sensitive adhesive composition Tg: -34°C, TIP: 0 wt%, no melting point).
(Comparative Example 3)
The main agent CMX AC1002-S16 and the cross-linking agent CMX KO1001-S17 were blended at a non-volatile ratio: main agent/cross-linking agent = 100/10 to obtain a pressure-sensitive adhesive composition (viscosity 100 mPa s, dry-cured pressure-sensitive adhesive composition Tg: -34°C, TIP: 55 wt%, no melting point).
(Comparative Example 4)
A pressure-sensitive adhesive composition was prepared only with the main agent CMX AB1002-S01 (olefin-based adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 5% by mass, viscosity 70 mPa s) (Tg of dried and cured pressure-sensitive adhesive composition: -9 ° C. , TIP: 0% by weight, no melting point).
(Comparative Example 5)
A pressure-sensitive adhesive composition was prepared only with the main agent CMX AB1003-S03 (olefin-based adhesive, prototype manufactured by Sumika Chemtex, non-volatile content 17% by mass, viscosity 40 mPa s) (Tg of dried and cured pressure-sensitive adhesive composition: -28 ° C. , TIP: 0 wt%, melting point 71°C).

Tg, TIP and melting point in Examples 1-6 and Comparative Examples 1-5 were measured by the following methods.
(Tg and melting point measurement by DSC)
The pressure-sensitive adhesive compositions of Examples 1 to 6 and Comparative Examples 1 to 5 were dried on release paper and cured at 40° C. for 3 days to obtain measurement samples. 8 to 10 mg of the measurement sample was weighed into an aluminum pan for DSC measurement and measured with DSC7020 (manufactured by Hitachi Ltd.). The temperature program starts from 20°C, increases the temperature to 200°C at 30°C/min, holds for 5 minutes, cools to -60°C at -10°C/min, holds for 5 minutes, and raises the temperature to 200°C at 10°C/min. → Hold for 5 minutes → End. Tg and melting point were measured using the method of JIS K 7121 using the data of the 2nd run (second temperature rise) of the measurement results. Regarding the melting point, whether or not a melting peak was observed, and if it was observed, the peak area, that is, the apex of the crystal melting peak at which the heat of crystal melting was 1 J/g or more was taken as the melting point.
(Measurement of toluene insolubles (TIP))
The pressure-sensitive adhesive compositions of Examples 1 to 6 and Comparative Examples 1 to 5 were dried on release paper and cured at 40° C. for 3 days to prepare measurement samples. 0.5 g (1) of the measurement sample (4 significant digits) and 100 ml of toluene (measured with a graduated cylinder) were weighed into a 150 ml sample bottle and heated at 80° C. for 3 hours with the lid closed sufficiently. During heating, the sample bottle was shaken 10 times in a circular motion every 30 minutes. After cooling to room temperature, the eluate was filtered through a wire mesh of #300 mesh, and the insoluble matter remaining on the wire mesh was dried. The mass of the insoluble matter (2) was calculated from the difference in the mass of the #300 mesh wire mesh before and after the test, and calculated by the following formula.
Toluene insoluble matter (% by mass) = (mass of insoluble matter / mass of sample for measurement) x 100

[Production of laminate A]
The pressure-sensitive adhesive compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were applied to a heat-shrinkable film (manufactured by Belica, product name Berry Shrink, olefin material, thickness 19 μm) with a bar coater, and at 50 ° C. It was dried for 2 minutes (thickness of adhesive layer after drying: 2 μm to 4 μm. This thickness was obtained by converting the amount of adhesive applied to density).
Polypropylene nonwoven fabric (manufactured by Tsujitomi Co., Ltd., product name Leafa LP0152D, basis weight: 15 g/m ² , melting point: 165° C.) or Mitsui Chemicals, Inc., product name Syntex PS-103, basis weight, is applied to the coating surface of the adhesive layer. Amount: 16 g/m ² , Melting point: 165° C.) were laminated together and temporarily pressure-bonded with a hand roller. After that, it was crimped with a laminator (VA-700, manufactured by Taihei Laminator Co., Ltd.) at a roller temperature of room temperature, a roller pressure of 0.2 MPa, and a delivery speed of 1 m/min. In Table 1, the adhesiveness was evaluated by press-bonding with a laminator.
After lamination, they were aged at 40° C. for 3 days to obtain a laminate A as a packaging material.
In addition, when pressure-sensitive adhesive compositions of Comparative Examples 4 and 5 were used, the heat-shrinkable film and the non-woven fabric were not adhered to each other when pressure-bonded with a laminator.

(Shrinkage test of laminate A)
The obtained laminate A was cut into a 12 cm square, and was shrunk by heating at 150° C. for 5 seconds while being fixed to an aluminum frame of 12 cm square at four corners. At that time, it was confirmed visually whether peeling occurred between the nonwoven fabric and the heat-shrinkable film.
The results are shown in the table below. In Table 1, ◯ indicates that no peeling was observed between the nonwoven fabric and the heat-shrinkable film, and x indicates that even a slight peeling was observed.
In addition, for the laminate A using the adhesive composition prepared in Examples 1 to 6, a sample similar to the above was separately cut out and subjected to heat load at 150 ° C. for 10 seconds without being fixed to an aluminum frame. It was confirmed that the film shrinks by 5% or more in the vertical and horizontal directions perpendicular to each other.
(Fusing test)
The resulting laminate A was subjected to a fusion cutting test using an automatic shrink packaging machine (HP-10Z type).
The heat-shrinkable films of the two laminates A were set in the sealing portion of the packaging machine in a state of being superimposed, and melted at a sealing temperature of 200° C., a gauge pressure of 0.5 MPa, and a crimping time of 1 second to confirm the melted portion.
The results are shown in the table below. In Table 1, a double circle indicates that the fusion cutting was possible, ○ indicates that there was no problem in practical use although the fusion cutting was partially defective, and x indicates that the fusion cutting could not be performed.

^＊：不織布がポリプロピレン不織布（株式会社ツジトミ製、製品名リーファＬＰ０１５２Ｄ、目付量：１５ｇ／ｍ^２、融点：１６５℃）
^＊＊：不織布がポリプロピレン不織布（三井化学株式会社製、製品名シンテックスＰＳ－１０３、目付量：１６ｇ／ｍ^２、融点：１６５℃）

^* : Nonwoven fabric is polypropylene nonwoven fabric (manufactured by Tsujitomi Co., Ltd., product name Leafa LP0152D, basis weight: 15 g/m ² , melting point: 165°C)
^** : The nonwoven fabric is a polypropylene nonwoven fabric (manufactured by Mitsui Chemicals, Inc., product name Syntex PS-103, weight per unit area: 16 g/m ² , melting point: 165°C).

The pressure-sensitive adhesive composition of the present application and a laminate using the same can be suitably used for various packaging materials and the like.

Claims (5)

A pressure-sensitive adhesive composition for bonding a heat-shrinkable film and a nonwoven fabric,
Containing an acrylic pressure-sensitive adhesive and an aromatic polyisocyanate cross-linking agent,
The dried and cured adhesive composition has a glass transition temperature (Tg) of −50° C. to −20° C. , a toluene insoluble content (TIP) of 2% by mass or more, and a melting point of 0° C. or less or amorphous. A pressure-sensitive adhesive composition characterized by having no melting point at . The pressure-sensitive adhesive composition according to claim 1, wherein the TIP is 53% by mass or less. Having an adhesive layer containing an acrylic pressure-sensitive adhesive and an aromatic polyisocyanate cross-linking agent between the heat-shrinkable film and the non-woven fabric,
The adhesive layer has a glass transition temperature (Tg) of −50° C. to −20° C. , a toluene insoluble content (TIP) of 2% by mass or more, and a melting point of 0° C. or less, or is amorphous and has no melting point. A laminate characterized by: 4. The laminate according to claim 3 , which exhibits a shrinkage rate of 5% or more in at least one direction under heat load at 150[deg.] C. for 10 seconds. A packaging material comprising the laminate according to claim 3 or 4 .