Adhesive, laminate, packaging material

Abstract

The present invention provides a solventless adhesive excellent in content resistance and less likely to cause redissolution of a printed layer, a laminate obtained using the adhesive, and a packaging material. The solventless adhesive contains a polyol composition (X) and a polyisocyanate composition (Y), the polyol composition (X) containing a polyol (A) which is a sugar alcohol derivative having a number average molecular weight of 450 or more and 1000 or less and having a functionality of 4 or more, and a polyester polyol (B) which is a reaction product of a composition containing a polyhydric alcohol and a polycarboxylic acid, the blending amount of the polyol (A) in the total amount of the polyol (A) and the polyester polyol (B) being 5% by mass or more and 30% by mass or less.

Description

Technical Field

[0001] This invention relates to adhesives, laminates obtained using the adhesives, and packaging materials. Background Technology

[0002] The laminates used in various packaging materials and labels are given design, functionality, preservation, convenience and transportability by laminating various plastic films, metal foils, paper and other substrates. In particular, the packaging formed by shaping the laminate into bags is used as packaging for food, medicine, detergents and the like.

[0003] Previously, the mainstream method for lamination used in packaging was to apply an adhesive dissolved in volatile organic solvents (sometimes called solvent-based laminating adhesives) to a substrate, evaporate the organic solvents during the drying process, and then bond the laminations to other substrates using a dry lamination method. However, in recent years, from the perspective of reducing environmental impact and improving the working environment, the demand for reactive two-component laminating adhesives that do not contain volatile organic solvents (hereinafter referred to as solvent-free adhesives) has been increasing (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-159548 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Solvent-free adhesives have many advantages, such as no drying process and no solvent discharge, energy saving and good operating costs, and no concerns about solvent residue in laminates after bonding plastic films together or laminates after bonding plastic films with metal foils or metal vapor-deposited layers. On the other hand, they also have disadvantages.

[0009] The components used in solvent-free adhesives need to be designed with low molecular weights to achieve a coatable viscosity when heated to approximately 40°C to 100°C. Therefore, solvent-free adhesives tend to have poor resistance to contents such as shampoos and conditioners, which can easily penetrate the adhesive layer (the cured coating of the adhesive) through the sealing film. Furthermore, in laminates used in packaging materials, a printed layer is generally applied to the back side (content side) of the outermost substrate (viewed from the contents) using printing ink. This printed layer is then bonded to other substrates via an adhesive. However, solvent-free adhesives containing low molecular weight polyester polyols contain substances that can easily cause the printed layer to redissolve.

[0010] The present invention was made in view of the following circumstances, and its object is to provide a solvent-free adhesive that has excellent resistance to contents and does not easily cause the printed layer to redissolve, a laminate obtained using the adhesive, and a packaging material.

[0011] Methods for solving problems

[0012] This invention relates to a solvent-free adhesive comprising a polyol composition (X) and a polyisocyanate composition (Y). The polyol composition (X) contains a polyol (A) that is a sugar alcohol derivative with a number average molecular weight of 450 or more and 1000 or less and is a functional group of 4 or more, and a polyester polyol (B) that is a reaction product of a composition comprising a polyol and a polycarboxylic acid. The amount of the polyol (A) in the total amount of the polyol (A) and the polyester polyol (B) is 5% by mass or more and 30% by mass or less.

[0013] Furthermore, the present invention relates to a laminate and a packaging material comprising the laminate, the laminate comprising a first substrate, a second substrate, and an adhesive layer for bonding the first substrate and the second substrate, the adhesive layer being a cured coating of the two-component curable adhesive.

[0014] Invention Effects

[0015] The adhesives according to the present invention can provide solvent-free adhesives with excellent resistance to contents and minimal redissolution of the printed layer, laminates with excellent resistance to contents and excellent printed appearance, and packaging materials. Detailed Implementation

[0016] <Adhesive>

[0017] The adhesive of the present invention is a two-component curing adhesive comprising a polyol composition (X) and a polyisocyanate composition (Y). The adhesive of the present invention will now be described in detail.

[0018] (Polyol Composition (X))

[0019] (Polyol (A))

[0020] The polyol composition (X) used in the adhesive of the present invention comprises a polyol (A) that is a sugar alcohol derivative with a number average molecular weight of 450 or more and 1000 or less, and is at least four-functional. It should be noted that a sugar alcohol derivative refers to a compound in which a portion of the hydroxyl group of a sugar alcohol is a salt, or a compound formed by the reaction of a portion of the hydroxyl group of a sugar alcohol with other functional groups. It should be noted that the number average molecular weight in this specification is a value determined by gel permeation chromatography (GPC) under the following conditions.

[0021] Measurement apparatus: HLC-8320GPC manufactured by Tosoh Corporation

[0022] Column: TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel1000HXL manufactured by Tosoh Corporation

[0023] Detector: RI (Differential Refractometer)

[0024] Data processing: MultiStation GPC-8020modelII manufactured by Tosoh Corporation

[0025] Measurement conditions: Column temperature 40℃

[0026] solvent tetrahydrofuran

[0027] Flow rate 0.35 ml / min

[0028] Standard: Monodisperse polystyrene

[0029] Sample: 100 μl of a tetrahydrofuran solution (calculated as 0.2% by mass based on resin solids) obtained by filtering it through a microfilter.

[0030] Specific examples of sugar alcohol derivatives include alkylene oxide adducts obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and alkylene oxide to sugar alcohols such as pentaerythritol, sucrose, xylitol, sorbitol, isomaltitol, lactitol, maltitol, and mannitol, or polyalkylene oxide adducts obtained by adding polyalkylene oxides such as polyethylene oxide, polypropylene oxide, and polybutylene oxide.

[0031] It is believed that by using polyol (A), the crosslinking density of the cured coating of the adhesive increases, thus improving its resistance to contents. Furthermore, while polyether polyols generally do not readily cause re-dissolution of the printed layer, it is further believed that sugar alcohol derivatives, with their higher viscosity compared to common polyether polyols, offer superior resistance to re-dissolution of the printed layer (ink solubility).

[0032] The amount of polyol (A) incorporated is 5% by mass or more and 30% by mass or less of the total amount of the polyester polyol (B) described later. This allows for the production of an adhesive with excellent resistance to contents, good coating adaptability, and a good pot life. More preferably, the amount of polyol (A) incorporated is 10% by mass or more of the total amount of the polyester polyol (B), and more preferably 25% by mass or less.

[0033] (Polyester Polyol (B))

[0034] Polyester polyol (B) is a reaction product of a polyvalent alcohol and a polycarboxylic acid. There are no particular limitations on the polyvalent alcohol used in the synthesis of polyester polyol (B), and polyols with two or more functionalities can be used. Examples of difunctional alcohols include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, 2,2,4-trimethyl-1,3-pentanediol, and aliphatic diols such as dimer diols.

[0035] Polyoxyethylene glycol, polyoxypropylene glycol and other ether glycols;

[0036] Modified polyether diols are obtained by ring-opening polymerization of aliphatic diols with various compounds containing cyclic ether bonds, such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether.

[0037] Lactone-based polyester polyols are obtained through the polycondensation reaction of aliphatic diols with various lactones such as lactol and ε-caprolactone.

[0038] Bisphenol A, bisphenol F, and other bisphenols;

[0039] Bisphenol alkyl oxide adducts obtained by adding bisphenol A, bisphenol F and other bisphenols to ethylene oxide, propylene oxide and other compounds.

[0040] Examples of polyols with three or more functions include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerol, hexanetriol, and pentaerythritol.

[0041] Modified polyether polyols are obtained by ring-opening polymerization of aliphatic polyols with various compounds containing cyclic ether bonds, such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether.

[0042] Lactone-based polyester polyols are obtained through the polycondensation reaction of aliphatic polyols with various lactones such as ε-caprolactone.

[0043] Examples of aliphatic polycarboxylic acids used in the synthesis of polyester polyols (B) include malonic acid, ethylmalonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, succinic anhydride, alkenylsuccinic anhydride, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, dimer acid, and trimer acid.

[0044] Alkyl esters of aliphatic polycarboxylic acids such as dimethyl malonate, diethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, diethyl heptaate, diethyl sebacate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, and diethyl maleate.

[0045] Alicyclic polycarboxylic acids such as 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, nadic anhydride, and chlorobridged anhydride;

[0046] Aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic anhydride, naphthalenedicarboxylic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, biphenyl dicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, benzophenone tetracarboxylic acid, benzophenone tetracarboxylic dianhydride, sodium isophthalate-5-sulfonate, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride;

[0047] Methyl esters of aromatic polycarboxylic acids such as dimethyl terephthalic acid and dimethyl 2,6-naphthalenedicarboxylate may be used, either one or two or more in combination.

[0048] By including polyester polyol (B) together with polyol (A), an adhesive with excellent resistance to contents can be produced.

[0049] In particular, if an aromatic polycarboxylic acid is included as a polycarboxylic acid, the resistance to contents is improved, and therefore it is preferred. The amount of the aromatic polycarboxylic acid in the polycarboxylic acid is preferably 25% by mass or more and 50% by mass or less. From the viewpoint of pot life, it is more preferably 40% by mass or less.

[0050] Furthermore, it is known that low molecular weight polyester polyols generally tend to easily cause the printed layer to redissolve. However, if the polyol contains diethylene glycol, the ink resistance can be improved without compromising the resistance to the contents, and therefore this is preferred. The amount of diethylene glycol in the polyol can be appropriately adjusted; for example, it is preferably 50% by mass or more.

[0051] Furthermore, if a substance obtained by lactone addition to a polyester polyol is used as the polyester polyol (B), the resistance to contents is improved, and therefore it is preferred.

[0052] (Polyol (C))

[0053] The polyol composition (X) may contain a polyol (C) other than polyol (A) and polyester polyol (B). The same polyol (C) exemplified as a raw material for polyester polyol (B) may be used. The amount of polyol (C) is not particularly limited, but is preferably limited to 20% by mass or less of the total amount of polyol (A), polyester polyol (B), and polyol (C).

[0054] The viscosity of the polyol composition (X) is adjusted to a range suitable for solventless lamination. As an example, it is adjusted to a viscosity of 100–5000 mPas, more preferably 500–3000 mPas, at 40–60°C. As another example, the viscosity of the polyol composition (X) can be adjusted by the backbone of the polyester polyol (B), its number-average molecular weight, and the plasticizer (E5) described later.

[0055] (Polyisocyanate composition (Y))

[0056] The polyisocyanate composition (Y) comprises a polyisocyanate compound (D) having multiple isocyanate groups. The polyisocyanate compound (D) is not particularly limited, and examples include aromatic diisocyanates, aromatic aliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and biuret forms, isocyanurate forms, adducts, urea carbamate forms, carbodiimide-modified forms, urea diketone-modified forms, and urethane prepolymers obtained by reacting these polyisocyanates with polyols, etc., which can be used alone or in combination.

[0057] Examples of aromatic diisocyanates include, but are not limited to, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also known as polymeric MDI or crude MDI), 1,3-phenyl diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, bianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4”-triphenylmethane triisocyanate.

[0058] Aromatic aliphatic diisocyanates refer to aliphatic isocyanates that have one or more aromatic rings in their molecules. Examples include meta- or terephthalic diisocyanate (also known as XDI) and α,α,α',α'-tetramethylphthalic diisocyanate (also known as TMXDI), but are not limited to these.

[0059] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylidene diisocyanate, 2,3-butylidene diisocyanate, 1,3-butylidene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate, but these are not the only examples.

[0060] Examples of alicyclic diisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (also known as IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanate methyl)cyclohexane, but these are not the only examples.

[0061] The polyol used in the synthesis of urethane prepolymers can be the same polyol exemplified as a raw material for polyester polyol (B). From the perspective of achieving lower viscosity of the adhesive and improving adhesive strength, at least one of polyalkylene glycol or polyester polyol is preferred.

[0062] The polyalkylene glycol is preferably in the range of 200 to 6,000 in number average molecular weight. The polyester polyol is preferably a substance obtained by reacting a polyalkylene glycol with an aliphatic polycarboxylic acid having 2 to 30 carbon atoms. Furthermore, the polyester polyol may use alcohols with 3 or more functions, such as glycerol, trimethylolpropane, or pentaerythritol, as its raw material alcohol component in a proportion of 10% by mass or less in the polyol composition.

[0063] For use as a flexible packaging substrate, from the perspective of imparting appropriate flexibility to the cured product, polyisocyanates obtained by reacting aromatic polyisocyanates with polyalkylene glycols with a number average molecular weight in the range of 200 to 6,000, and polyisocyanates obtained by reacting aromatic polyisocyanates with polyester polyols with a number average molecular weight in the range of 200 to 3,000, are preferred. From the perspective of achieving an appropriate resin viscosity and excellent coatability, polyisocyanates with an isocyanate content of 5 to 20% by mass based on titration (using di-n-butylamine) are preferred.

[0064] On the other hand, when used on rigid substrates, from the perspective of excellent adhesive strength, polyisocyanates obtained by reacting aromatic polyisocyanates with polyester polyols with a number average molecular weight in the range of 200 to 3,000, and polyisocyanates obtained by reacting aromatic polyisocyanates with a mixture of polyester polyols with a number average molecular weight in the range of 200 to 3,000 and polyalkylene glycols with a number average molecular weight in the range of 200 to 6,000, are preferred. From the perspective of still achieving a suitable resin viscosity and excellent coatability, polyisocyanates with an isocyanate content of 5 to 20% by mass based on conventional methods (using di-n-butylamine) are preferred.

[0065] When the polyisocyanate compound (D) is a urethane prepolymer, the equivalent ratio of isocyanate groups to hydroxyl groups [NCO] / [OH] for the reaction is in the range of 1.5 to 5.0, which is preferred from the point of view that the viscosity of the adhesive is in an appropriate range and the coatability becomes good.

[0066] The viscosity of the polyisocyanate composition (Y) was adjusted to a range suitable for solventless lamination. As an example, the viscosity at 40°C was adjusted to a range of 500–5000 mPas, more preferably 500–3000 mPas. As another example, the viscosity of the polyisocyanate composition (Y) could be adjusted by the amount of urethane prepolymer and the amount of low molecular weight isocyanate compound incorporated.

[0067] (Other components of the adhesive (E))

[0068] The adhesive of the present invention may contain components other than those described above. Other components (E) may be included in either or both of the polyol composition (X) or the polyisocyanate composition (Y), or may be prepared separately beforehand and mixed with the polyol composition (X) and the polyisocyanate composition (Y) just before the adhesive is applied. The components are described below.

[0069] (Catalyst (E1))

[0070] Examples of catalysts (E1) include metal catalysts, amine catalysts, and aliphatic cyclic amide compounds.

[0071] Examples of metal-based catalysts (E1) include metal complex-based, inorganic metal-based, and organometallic catalysts. Examples of metal complex-based catalysts include acetylacetone salts of metals selected from Fe (iron), Mn (manganese), Cu (copper), Zr (zirconium), Th (thorium), Ti (titanium), Al (aluminum), and Co (cobalt), such as iron acetylacetone, manganese acetylacetone, copper acetylacetone, and zirconium oxide acetylacetone.

[0072] Examples of inorganic metal catalysts include substances selected from Sn, Fe, Mn, Cu, Zr, Th, Ti, Al, and Co.

[0073] Examples of organometallic catalysts include organozinc compounds such as zinc octanoate, zinc neodecanoate, and zinc naphthenate; organotin compounds such as tin diacetate, tin dioctanoate, tin dioleate, tin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin oxide, and dibutyltin dichloride; organonitrile compounds such as nickel octanoate and nickel naphthenate; organocobalt compounds such as cobalt octanoate and cobalt naphthenate; organobismuth compounds such as bismuth octanoate, bismuth neodecanoate, and bismuth naphthenate; titanium compounds such as tetraisopropyl titanate, dibutyltitanium dichloride, tetrabutyl titanate, butoxytitanium trichloride, and titanium chelates that use at least one of aliphatic diketones, aromatic diketones, or alcohols with 2 to 10 carbon atoms as ligands.

[0074] Examples of amine catalysts include triethylenediamine, 2-methyltriethylenediamine, quinine ring, 2-methylquinine ring, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropanediamine, N,N,N',N”,N”-pentamethyldiethylenetriamine, N,N,N',N”,N”-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N',N”,N”-pentamethyldipropylenetriamine, N,N,N',N’-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl) ether, dimethylethanolamine, dimethylisopropanolamine, dimethylaminoethoxyethanol, N,N-dimethyl-N'-(2-hydroxyethyl)ethylenediamine, N,N-dimethyl-N'-(2-hydroxyethyl)propanediamine, bis(dimethylaminopropyl)amine, and bis(di... Methylaminopropyl)isopropanolamine, 3-quinol, N,N,N',N'-tetramethylguanidine, 1,3,5-tris(N,N-dimethylaminopropyl)hexahydro-triazine, 1,8-diazabicyclo[5.4.0]undecene-7, N-methyl-N'-(2-dimethylaminoethyl)piperazine, N,N'-dimethylpiperazine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, 1-methylimidazolium, 1,2-dimethylimidazolium, 1-isobutyl-2-methylimidazolium, 1-dimethylaminopropylimidazolium, N,N-dimethylhexanolamine, N-methyl-N'-(2-hydroxyethyl)piperazine, 1-(2-hydroxyethyl)imidazolium, 1-(2-hydroxypropyl)imidazolium, 1-(2-hydroxyethyl)imidazolium, 1-(2-hydroxypropyl)imidazolium, 1-(2-hydroxyethyl)-2-methylimidazolium, 1-(2-hydroxypropyl)-2-methylimidazolium, etc.

[0075] Examples of aliphatic cyclic amide compounds include δ-valeramide, ε-caprolactam, ω-heptanolactam, η-octanolactam, and β-propiolactam. Among them, ε-caprolactam is more effective in promoting curing.

[0076] (Anhydride (E2))

[0077] As the anhydride (E2), cyclic aliphatic anhydrides, aromatic anhydrides, unsaturated carboxylic anhydrides, etc. can be cited, and one kind or two or more kinds in combination can be used. More specifically, for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, dodecenyl succinic anhydride, polyadipic anhydride, polynonanoic anhydride, polysebacic anhydride, poly(ethyl octadecanedioic) anhydride, poly(phenyl hexadecanedioic) anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methyl humic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexenedicarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride, ethylene glycol bis-trimellitate dianhydride, chlorendic anhydride, nadic anhydride, methyl nadic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, etc. can be cited.

[0078] In addition, as the anhydride (E2), a substance obtained by modifying the above compound with a diol can also be used. As the diol that can be used for modification, alkylene diols such as ethylene glycol, propylene glycol, and neopentyl glycol can be cited; polyether diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol can be cited, etc. In addition, a copolymer polyether diol of two or more kinds of diols and / or polyether diols among them can also be used.

[0079] (Coupling agent (E3))

[0080] As the coupling agent (E3), silane coupling agents, titanate coupling agents, aluminum coupling agents, etc. can be cited.

[0081] As the silane coupling agent, amino silanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane can be cited; epoxy silanes such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane can be cited; vinyl silanes such as vinyl tris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane can be cited; hexamethyldisilazane, γ-mercaptopropyltrimethoxysilane, etc.

[0082] Examples of titanate-based coupling agents include tetraisopropoxy titanium, tetra-n-butoxy titanium, tetrabutyl titanate dimer, tetrastearate titanate, acetylacetone titanium, lactate titanium, tetraoctyl glycol titanate, lactate titanium, and tetrastearoxy titanium.

[0083] Examples of aluminum-based coupling agents include aluminum acetylalkoxydiisopropoxide.

[0084] (Pigment (E4))

[0085] As for pigments (E4), there are no particular restrictions. Examples include organic pigments, inorganic pigments, and plastic pigments, such as extender pigments, white pigments, black pigments, gray pigments, red pigments, brown pigments, green pigments, blue pigments, metallic pigments, luminescent pigments, and pearl pigments, as well as pigments listed in the 1970 edition of the Paint Raw Materials Handbook (edited by the Japan Paint Industry Association).

[0086] Examples of pigments that can be categorized as body pigments include precipitated barium sulfate, lead oxide, precipitated calcium carbonate, calcium bicarbonate, calcite, alumina white, silica, hydrated micronized silica (white carbon), ultrafine anhydrous silica (AEROSIL), silica sand (silica sand), talc, precipitated magnesium carbonate, bentonite, clay, kaolin, and loess.

[0087] Specific examples of organic pigments include various insoluble azo pigments such as benzidine yellow, Hansa yellow, and Lake red 4R; soluble azo pigments such as Lake red C, carmine 6B, and maroon 10; various (copper) phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; various basic dyeing lakes such as rhodamine lake and methyl violet lake; various mordant dyes such as quinoline lake and fast sky blue; various vat dyes such as anthraquinone pigments, thioindigo pigments, and violet ketone pigments; various quinacridone pigments such as Cinquasia Red B; various dioxazine pigments such as dioxazine violet; various condensed azo pigments such as Gummel; and aniline black, etc.

[0088] As inorganic pigments, examples include various chromates such as chrome yellow, zinc chromate, and molybdenum orange; various ferrocyanide compounds such as Prussian blue; various metal oxides such as titanium dioxide, zinc white, brownish yellow, iron oxide, iron oxide, chromium oxide green, and zirconium oxide; various sulfides or selenides such as cadmium yellow, cadmium red, and mercuric sulfide; various sulfates such as barium sulfate and lead sulfate; various silicates such as calcium silicate and ultramarine; various carbonates such as calcium carbonate and magnesium carbonate; various phosphates such as cobalt violet and manganese violet; various metal powder pigments such as aluminum powder, gold powder, silver powder, copper powder, bronze powder, and brass powder; flake pigments of these metals, mica, and flake pigments; metal pigments such as mica coated with metal oxides, flake pigments, and mica-like iron oxide pigments; pearl pigments; graphite and carbon black, etc.

[0089] Examples of plastic pigments include DIC Corporation's "GRANDOLL PP-1000" and "PP-2000S".

[0090] Regarding the pigment (E4) used, it can be selected appropriately according to the purpose. For example, in terms of durability, weather resistance, and excellent design, inorganic oxides such as titanium dioxide and zinc white are preferred as white pigments, while carbon black is preferred as a black pigment.

[0091] Regarding the amount of pigment (E4), as an example, it is 1 to 400 parts by mass relative to 100 parts by mass of the total solid components of the polyol composition (X) and the polyisocyanate composition (Y). More preferably, it is set to 10 to 300 parts by mass to improve adhesion and anti-blocking properties.

[0092] (Plasticizer (E5))

[0093] Examples of plasticizers include phthalic acid-based plasticizers, fatty acid-based plasticizers, aromatic polycarboxylic acid-based plasticizers, phosphoric acid-based plasticizers, polyol-based plasticizers, epoxy-based plasticizers, polyester-based plasticizers, and carbonate-based plasticizers.

[0094] Examples of phthalic acid-based plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, diheptyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octyl phthalate, dinonyl phthalate, diisononyl phthalate, didecyl phthalate, diisodecyl phthalate, di(tridecyl) phthalate, di(undecyl) phthalate, and phthalic acid-based plasticizers. Phthalate ester plasticizers include dilaurate formate, distearate phthalate, diphenyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, octyl decyl phthalate, dimethyl isophthalate, di-(2-ethylhexyl) isophthalate, and diisooctyl isophthalate; tetrahydrophthalate ester plasticizers include di-(2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydrophthalate, and diisodecyl tetrahydrophthalate.

[0095] Examples of fatty acid-based plasticizers include di-n-butyl adipate, di-(2-ethylhexyl) adipate, diisodecyl adipate, diisononyl adipate, di(C6-C10 alkyl) adipate, and di(butyl diethylene glycol) adipate (Japanese: ジブチルジグリコールアジペート), etc.; and di-n-hexyl azelate, di-(2-ethylhexyl) azelate, etc. Azelaic acid-based plasticizers such as diisooctyl azelate; sebamic acid-based plasticizers such as di-n-butyl sebacate, di-(2-ethylhexyl) sebacate, and diisononyl sebacate; maleic acid-based plasticizers such as dimethyl maleate, diethyl maleate, di-n-butyl maleate, and di-(2-ethylhexyl) maleate; and fumaric acid-based plasticizers such as di-n-butyl fumarate and di-(2-ethylhexyl) fumarate. Examples of plasticizers include: itaconic acid-based plasticizers such as monomethyl itaconic acid, monobutyl itaconic acid, dimethyl itaconic acid, diethyl itaconic acid, dibutyl itaconic acid, and di-(2-ethylhexyl) itaconic acid; stearic acid-based plasticizers such as n-butyl stearate, glyceryl monostearate, and diethylene glycol distearate; oleic acid-based plasticizers such as butyl oleate, glyceryl monooleate, and diethylene glycol monooleate; citric acid-based plasticizers such as triethyl citrate, tri-n-butyl citrate, acetylated triethyl citrate, acetylated tributyl citrate, and acetylated tri-(2-ethylhexyl) citrate; ricinoleic acid-based plasticizers such as methyl acetylated ricinoleate, acetylated butyl ricinoleate, glyceryl monoricinoleate, and diethylene glycol monoricinoleate; and other fatty acid-based plasticizers such as diethylene glycol monolaurate, diethylene glycol dinonanoate, and pentaerythritol fatty acid esters.

[0096] Examples of aromatic polycarboxylic acid plasticizers include trimellitic acid plasticizers such as tri-n-hexyl trimellitate, tri-(2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisooctyl trimellitate, triisononyl trimellitate, tridecyl trimellitate, and triisodecyl trimellitate; and pyromellitic acid plasticizers such as tetra-(2-ethylhexyl) pyromellitic acid and tetra-n-octyl pyromellitic acid.

[0097] Examples of phosphoric acid-based plasticizers include triethyl phosphate, tributyl phosphate, tri-(2-ethylhexyl) phosphate, tri(butoxyethyl) phosphate, triphenyl phosphate, octyl diphenyl phosphate, toluene diphenyl phosphate, toluene phenyl phosphate, tri(toluene) phosphate, tri(xylene) phosphate, tri(chloroethyl) phosphate, tri(chloropropyl) phosphate, tri(dichloropropyl) phosphate, and tri(isopropylphenyl) phosphate.

[0098] Examples of polyol-based plasticizers include diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate), and dibutyl methylene bis(thioglycolic acid) ester; and glycerol-based plasticizers such as glyceryl monoacetate, glyceryl triacetate, and glyceryl tributyrate.

[0099] Examples of epoxy-based plasticizers include epoxidized soybean oil, epoxidized butyl stearate, epoxidized di(2-ethylhexyl) phthalate, epoxidized diisodecyl phthalate, epoxidized triglyceride, epoxidized octyl oleate, and epoxidized decyl oleate.

[0100] Examples of polyester plasticizers include adipic acid-based polyesters, sebacic acid-based polyesters, and phthalic acid-based polyesters.

[0101] Examples of carbonate-based plasticizers include propylene carbonate and ethylene carbonate.

[0102] In addition, other plasticizers include partially hydrogenated terphenyl, adhesive plasticizers, diallyl phthalate, acrylic monomers, oligomers, and other polymeric plasticizers. These plasticizers can be used alone or in combination of two or more.

[0103] (Phosphoric acid compound (E6))

[0104] Examples of phosphoric acid compounds (E6) include phosphoric acid, pyrophosphate, triphosphate, methyl phosphate, ethyl phosphate, butyl phosphate, dibutyl phosphate, 2-ethylhexyl phosphate, bis(2-ethylhexyl) phosphate, isododecyl phosphate, butoxyethyl phosphate, oleic acid phosphate, tetradecyl phosphate, 2-hydroxyethyl methacrylate, polyoxyethylene alkyl ether phosphate, etc.

[0105] (Compound (E7))

[0106] From the perspective of improving adhesion to the metal substrate, it is also preferable to include at least one compound (E7) selected from 2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvalerate. As compound (E7), at least one of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutyric acid is more preferred. The amount of compound (E7) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 10% by mass or less, and more preferably 2.5% by mass or less of the polyol composition (X).

[0107] (Form of adhesive)

[0108] The adhesive of the present invention can be used in a solvent-free form. It should be noted that, in this specification, "solvent-free" adhesive refers to the form of adhesive used in the following method, namely the so-called solvent-free lamination method: the polyol composition (X) and the polyisocyanate composition (Y) are substantially free of esters such as ethyl acetate, butyl acetate, and cellosol acetate, ketones such as acetone, methyl ethyl ketone, isobutyl ketone, and cyclohexanone, ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane and dichloroethane, dimethyl sulfoxide, and dimethyl sulfonamide, especially ethyl acetate or methyl ethyl ketone, and after the adhesive is applied to the substrate, it is bonded to other substrates without a process of heating in an oven or the like to evaporate the solvent. When trace amounts of organic solvents used as reaction media during the manufacture of the components of the polyol composition (X) and the polyisocyanate composition (Y) are not completely removed, and thus remain in the polyol composition (X) and the polyisocyanate composition (Y), it can be understood that they are substantially free of organic solvents. Furthermore, if the polyol composition (X) contains a low molecular weight alcohol, the low molecular weight alcohol reacts with the polyisocyanate composition (Y) to become part of the coating film; therefore, it is not necessary to allow it to evaporate after application. Thus, this form is also treated as a solvent-free adhesive, and the low molecular weight alcohol is not considered an organic solvent.

[0109] The adhesive of the present invention is preferably used in a formulation in which the molar ratio of the isocyanate groups [NCO] contained in the polyisocyanate composition (Y) to the molar ratio of the hydroxyl groups [OH] contained in the polyol composition (X) is 1.0 to 3.0.

[0110] <Layered Body>

[0111] The laminate of the present invention is obtained by laminating multiple substrates (films or papers) using the adhesive of the present invention and a solvent-free lamination method. There are no particular limitations on the films used; films appropriate to the intended application can be selected. For example, for food packaging, examples include polyethylene terephthalate (PET) films, polystyrene films, polyamide films, polyacrylonitrile films, polyethylene films (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film), polypropylene films (CPP: non-stretch polypropylene film, OPP: biaxially oriented polypropylene film), polyolefin films, polyvinyl alcohol films, ethylene-vinyl alcohol copolymer films, etc.

[0112] The film can be a film that has undergone stretching treatment. As a stretching treatment method, resin is typically melted and extruded into a sheet using methods such as extrusion film forming, followed by simultaneous biaxial stretching or successive biaxial stretching. In the case of successive biaxial stretching, longitudinal stretching is usually performed first, followed by transverse stretching. Specifically, a method combining longitudinal stretching utilizing the speed difference between rollers with transverse stretching using a tenter frame is commonly used.

[0113] Various surface treatments, such as flame treatment and corona discharge treatment, can be applied to the membrane surface as needed to form an adhesive layer without defects such as membrane rupture or depression.

[0114] Alternatively, membranes with vapor-deposited layers of metals such as aluminum, silicon dioxide, and alumina, or barrier membranes containing gas barrier layers such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and vinylidene chloride can be used. By using such membranes, laminates that provide barrier properties against water vapor, oxygen, alcohols, inactive gases, and volatile organic compounds (fragrances) can be produced.

[0115] There are no particular limitations on the paper itself; any known paper substrate can be used. Specifically, it can be manufactured using natural papermaking fibers such as wood pulp and a known papermaking machine, but the papermaking conditions are not specifically specified. Examples of natural papermaking fibers include wood pulps such as softwood pulp and hardwood pulp, non-wood pulps such as Manila hemp pulp, sisal pulp, and flax pulp, as well as pulps that have undergone chemical modification. As for the type of pulp, chemical pulps based on sulfate hydrolysis, acid / neutral / alkaline sulfite hydrolysis, sodium salt hydrolysis, etc., milled pulps, chemi-milled pulps, thermomechanical pulps, etc., can be used. Additionally, various commercially available high-quality papers, coated papers, lining papers, impregnated papers, corrugated board, and paperboard can also be used.

[0116] Laminates obtained using the adhesive of the present invention exhibit excellent resistance to contents containing components such as shampoo, conditioner, and softener that reach the adhesive layer through sealing films such as CPP films and LLDPE films, leading to degradation of the adhesive layer and reduction of adhesive strength. Therefore, the adhesive of the present invention is preferably used as an adhesive for bonding a substrate to a sealing film.

[0117] Specific examples of such compositions include Nyl film / transparent vapor-deposited PET film / adhesive layer / sealing film of the present invention, PET film / transparent vapor-deposited PET film / adhesive layer / sealing film of the present invention, PET film / aluminum foil / adhesive layer / sealing film of the present invention, PET film / aluminum foil / adhesive layer / PET film / sealing film of the present invention, and PET film / aluminum vapor-deposited PET film / adhesive layer / sealing film of the present invention. As other compositions, laminates comprising Nyl film / aluminum vapor-deposited PET film / adhesive layer / sealing film of the present invention are also preferred due to their excellent resistance to contents. In these laminates, the adhesive layers other than the adhesive layer of the present invention can be bonded using general adhesives or the adhesive of the present invention. It should be noted that laminates used for packaging materials typically have a printed layer (described later) at appropriate locations, but this is omitted in the examples above. When higher strength, such as puncture resistance, is required, a transparent vapor-deposited Nyl film can be used instead of an aluminum vapor-deposited PET film or a transparent vapor-deposited PET film.

[0118] The laminate of the present invention may have a printing layer disposed between the adhesive layer and the substrate (usually the outermost substrate relative to the contents). The printing layer is formed using various printing inks such as gravure ink, flexographic ink, offset ink, stencil ink, and inkjet ink, and by conventional printing methods used for printing on films.

[0119] The adhesive of the present invention, preheated to approximately 40°C to 100°C, is applied to a film or paper material that serves as the substrate using a gravure roller or similar roller coating process. Immediately after application, another substrate is bonded to obtain the laminate of the present invention. After lamination, an aging treatment is preferably performed. The aging temperature is preferably room temperature to 70°C, and the aging time is preferably 6 to 240 hours.

[0120] The amount of adhesive applied can be adjusted appropriately; for example, it is 1 g / m². 2 Above and 5g / m 2 The following applies. If the amount of adhesive applied increases, it may become easier for the adhesive to tangle and shift. From a processability point of view, 1 g / m² is preferable. 2 Above and 3g / m 2 the following.

[0121] The laminate of the present invention is formed by bonding two substrates together using the adhesive of the present invention, but other substrates may also be included as needed. As a method for laminating other substrates, known methods such as dry lamination, solvent-free lamination, hot lamination, heat sealing, and extrusion lamination can be used. The adhesive used may or may not be the adhesive of the present invention. The same substrates as those described above can be used as other substrates.

[0122] Packaging Materials

[0123] Regarding the packaging material of the present invention, it is manufactured by forming the above-mentioned laminated body into a bag shape and then heat-sealing it. Various packaging materials are available, including three-sided sealed bags, four-sided sealed bags, corner-supported bags, pillow-shaped bags, top-mounted bottomed containers, Tetra Pak cartons, brick-shaped bags, tube containers, paper cups, and lids. Furthermore, the packaging material of the present invention can be appropriately designed with easy-opening and resealing mechanisms.

[0124] The packaging material of this invention can primarily be used industrially as a packaging material for filling food, detergents, and pharmaceuticals. Specific applications include, as detergents and pharmaceuticals, liquid washing detergents, liquid kitchen detergents, liquid bath detergents, liquid bath soaps, liquid shampoos, liquid conditioners, and pharmaceutical tablets. Additionally, it can also be used as a secondary packaging material for packaging the aforementioned containers.

[0125] Example

[0126] The present invention will be described in more detail below with specific examples and embodiments, but the present invention is not limited to these embodiments. It should be noted that in the following examples, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0127] <Polyol Composition (X)>

[0128] (Synthesis of polyester polyol (B-1))

[0129] In a flask equipped with a stirrer, thermometer, nitrogen inlet tube, distillation tube, and moisture separator, 13.3 parts of ethylene glycol, 28.5 parts of diethylene glycol, and 3.0 parts of trimethylolpropane were added to the reaction vessel. The mixture was stirred under nitrogen atmosphere and heated to 100°C. Then, 35.7 parts of adipic acid and 19.1 parts of isophthalic acid were added at 100–110°C. The mixture was slowly heated, maintaining the internal temperature at 240°C, while stirring for 8 hours to obtain polyester polyol (B)-1.

[0130] (Synthesis of polyester polyols (B-2) to (B-6))

[0131] By changing the polyhydric alcohol, polycarboxylic acid, and reaction time used in the synthesis to those listed in Table 1, and otherwise operating in the same manner as for polyester polyol (B-1), polyester polyols (B-2) to (B-6) were obtained. It should be noted that "aromatic carboxylic acid complexation amount" in the table refers to the complexation amount (mass %) of the aromatic polycarboxylic acid in the polycarboxylic acid used to synthesize polyester polyol (B), and "DEG complexation amount" refers to the complexation amount (mass %) of diethylene glycol in the polyhydric alcohol used to synthesize polyester polyol (B). Furthermore, the detailed information of the compounds listed in the table is as follows.

[0132] AA: Adipic acid

[0133] IPA: Isophthalic acid

[0134] DEG: Diethylene glycol

[0135] EG: Ethylene glycol

[0136] PPG400: SANNIX PK-400GD (SANYO chemical formation)

[0137] TMP: Trimethylolpropane

[0138] [Table 1]

[0139]

[0140] (Preparation of polyol composition (X))

[0141] Following the formulations shown in Tables 2-4, polyol composition (X) was obtained by combining polyol (A), polyester polyol (B), and additive (dimethylolpropionic acid). It should be noted that the polyol (A) used in the preparation of polyol composition (X) is shown below.

[0142] Polyol (A-1): SANNIX HD-402 (manufactured by Sanyo Chemical Industry, pentaerythritol-based polyether polyol, 4 functional groups, number average molecular weight 600)

[0143] Polyol (A-2): SANNIX HS-209 (manufactured by Sanyo Chemical Industry, sucrose-based polyether polyol, 6 functional groups, number average molecular weight 600)

[0144] Polyol (A-3): SANNIX SP-750 (manufactured by Sanyo Chemical Industry, polyoxypropylene sorbitol ether, 6-functional, number average molecular weight 700)

[0145] Polyol (A-4): EXCENOL 385SO (prepared by AGC, propylene oxide adduct of sorbitol, 6-functional, number average molecular weight 500)

[0146] Polyol (A'-1): SANNIX PP-600 (manufactured by Sanyo Chemical Industry, polypropylene glycol, 2-functional, number average molecular weight 600)

[0147] Polyol (A'-2): SANNIX GP-600 (manufactured by Sanyo Chemical Industry, polyoxypropylene triol, 3-functional, number average molecular weight 600)

[0148] <Polyisocyanate Composition (Y)>

[0149] (Synthesis of polyisocyanate composition (Y-1))

[0150] 36 parts of 4,4'-diphenylmethane diisocyanate and 19 parts of 2,4'-diphenylmethane diisocyanate were added to a flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was heated to 60°C under a nitrogen atmosphere with stirring. 11 parts of polypropylene glycol with a number average molecular weight of 400, 22 parts of polypropylene glycol with a number average molecular weight of 1000, and 11 parts of polypropylene glycol with a number average molecular weight of 2000 were added dropwise in several portions. The mixture was stirred for 5–6 hours to complete the urethane esterification reaction. A polyisocyanate composition (Y-1) with an NCO group content of 13.5% and a viscosity of 1500 mPa·s was obtained.

[0151] (Synthesis of polyisocyanate composition (Y-2))

[0152] A mixture of 60.7 parts adipic acid, 28.2 parts ethylene glycol, and 11.1 parts diethylene glycol was added to a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen inlet pipe, distillation tube, and moisture separator. The mixture was slowly heated, keeping the temperature at the top of the distillation tube below 100°C, and the internal temperature was maintained at 220°C. The esterification reaction was terminated when the acid value fell below 2.0 mg KOH / g, yielding the intermediate polyester polyol.

[0153] 30 parts of 4,4'-diphenylmethane diisocyanate and 30 parts of 2,4'-diphenylmethane diisocyanate were added to a flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was heated to 60°C under a nitrogen atmosphere with stirring. 40 parts of the synthesized intermediate polyester polyol were added dropwise in several portions, and the mixture was stirred for 5–6 hours to complete the carbamate reaction. A polyisocyanate composition (Y-2) with an NCO group content of 14.0% and a viscosity of 3000 mPa·s was obtained.

[0154] (Synthesis of polyisocyanate composition (Y-3))

[0155] 55 parts of 4,4'-diphenylmethane diisocyanate were added to a flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was heated to 60°C under a nitrogen atmosphere while stirring. Eleven parts of polypropylene glycol with a number-average molecular weight of 400, 22 parts of polypropylene glycol with a number-average molecular weight of 1000, and 11 parts of polypropylene glycol with a number-average molecular weight of 2000 were added dropwise in several portions. The mixture was stirred for 5–6 hours to complete the carbamate reaction. A polyisocyanate composition (Y-3) with an NCO group content of 13.6% and a viscosity of 2000 mPa·s was obtained.

[0156] <Preparation of Adhesives>

[0157] The polyol composition (X) and the polyisocyanate composition (Y) heated to 40°C were mixed according to the formulations shown in Tables 2-4 to obtain the solvent-free adhesives of the Examples and Comparative Examples.

[0158] [Table 2]

[0159]

[0160] [Table 3]

[0161]

[0162] [Table 4]

[0163]

[0164] <Evaluation>

[0165] (Curing speed)

[0166] A TESTER SANGYO test laminator was used with a coating weight of 1.8 g / m². 2 An adhesive was applied to a biaxially stretched nylon membrane (Unitika Co., Ltd., "EMBLEM", 15 μm thick), which was then laminated with a linear low-density polyethylene membrane (Tohcello Co., Ltd., "TUX-HC", 60 μm thick). The laminate was aged at 40°C for 6 hours to obtain a laminate. The polyethylene membranes of the laminate were then positioned face-to-face and subjected to a pressure of 0.1 MPa / cm². 2 Heat sealing was performed at a temperature of 180℃ and a time of 1 second. The heat seal strength between polyethylene films was measured at a speed of 300 mm / min and evaluated according to the following criteria. The results are summarized in Tables 5-7.

[0167] ◎:40N / 15mm or more

[0168] ○: 20N / 15mm or more but less than 40N / 15mm

[0169] ×: Less than 20N / 15mm

[0170] (Applicable period)

[0171] After mixing the polyol composition (X) and the polyisocyanate composition (Y), the viscosity of the adhesive was measured after standing at 40°C for 30 minutes. The results were evaluated according to the following criteria and summarized in Tables 5-7.

[0172] ◎: Less than 3000 mPa·s

[0173] 〇: Above 3000 mPa·s and below 5000 mPa·s

[0174] ×: Above 5000 mPa·s

[0175] (Ink solubility)

[0176] The urethane-based laminating ink (Finart R794 White G3; manufactured by DIC Corporation) was adjusted to 15 seconds (25°C) using a Zein cup #3 manufactured by a clutch company. The ink was then printed onto a corona-treated PET (polyethylene terephthalate) film (Toyosho PET film E5102#12) using a gravure printing press equipped with a 43μm deep gravure plate. The film was then dried or cured in a 70°C oven to form a printed layer on the PET film.

[0177] 1 g of an adhesive containing a polyol composition (X) and a polyisocyanate composition (Y) was dropped onto the printed material. After being placed in an oven at 50°C for 3 minutes, the area containing the adhesive was rubbed with a black cotton swab. The transfer rate of white ink from the printed material to the black cotton swab was evaluated, and the results are summarized in Tables 5–7.

[0178] ◎: 0 to less than 10%

[0179] 〇: 10~less than 50%

[0180] ×: 50%~100%

[0181] (Tolerance for contents)

[0182] On a biaxially stretched nylon membrane (Unitika Co., Ltd. "EMBLEM", membrane thickness 15μm), an adhesive of 2.0 g / m² was applied using a test laminator (TESTER SANGYO). 2 The aluminum-deposited surface of an aluminum-deposited PET film (manufactured by Toray Film Processing Co., Ltd., 1310) was laminated to the PET film surface and aged at 40°C for 3 days. Next, 2.0 g / m² of adhesive was applied to the PET film surface of the aluminum-deposited PET film using a test laminator (manufactured by TESTER SANGYO). 2 The film was laminated with a linear low-density polyethylene film (Tohcello Corporation's "TUX-HC", film thickness 60μm) and aged at 40℃ for 3 days to obtain an ONy / VMPET / LLDPE laminate.

[0183] A 120mm × 120mm bag was made using the obtained laminate, filled with 70g of shampoo (Pantene, manufactured by P&G), and then heat-sealed. After applying a 3-week accelerator test at 60°C to the bag, the adhesive strength between the VMPET / LLDPE films was measured and evaluated according to the following criteria. The results are summarized in Tables 5–7.

[0184] ◎: VMPET film is broken, or the bonding strength is above 4N / 15mm.

[0185] 〇: 3N / 15mm or more but less than 4N / 15mm

[0186] ×: Less than 3N / 15mm [Table 5]

[0187]

[0188] [Table 6]

[0189]

[0190] [Table 7]

[0191]

Claims

1. A solvent-free adhesive comprising a polyol composition X and a polyisocyanate composition Y, The polyisocyanate composition Y comprises a urethane prepolymer obtained by reacting a polyisocyanate with a polyol. The polyol composition X contains: polyol A with a number average molecular weight of 450 or more and 1000 or less, and... Polyester polyol B is a reaction product of a composition comprising polyvalent alcohols and polycarboxylic acids. The polyol A is a sugar alcohol derivative with four or more functions, which is an adduct obtained by adding epoxides or polyepoxides to a sugar alcohol. The polyvalent alcohol includes diethylene glycol. The aromatic polycarboxylic acid constitutes a complexation amount of 25% by mass or more and 50% by mass or less in the polycarboxylic acid. The amount of polyol A in the total amount of polyol A and polyester polyol B is more than 5% by mass and less than 30% by mass.

2. The solvent-free adhesive according to claim 1, wherein, The aromatic polycarboxylic acid constitutes a complexation amount of 25% by mass or more and 40% by mass or less in the polycarboxylic acid.

3. The solvent-free adhesive according to claim 1 or 2, wherein, Diethylene glycol accounts for more than 20.3% by mass in the polyvalent alcohols.

4. The solvent-free adhesive according to claim 1 or 2, wherein, Diethylene glycol accounts for more than 50% by mass in the polyvalent alcohol.

5. The solvent-free adhesive according to claim 1 or 2, wherein, The polyester polyol B was obtained by lactone modification.

6. The solvent-free adhesive according to claim 4, wherein, The polyester polyol B was obtained by lactone modification.

7. A laminate comprising a first substrate, a second substrate, and an adhesive layer disposed between the first substrate and the second substrate. The adhesive layer is a cured coating of the solvent-free adhesive as described in any one of claims 1 to 6.

8. A packaging material comprising the laminate of claim 7.

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