Laminating adhesives, laminates, and additives for laminating adhesives

Abstract

To provide a laminate adhesive which is easily blended, has a high degree of freedom in formulation, has excellent content resistance (acid resistance) and can be subjected to hot water treatment and a laminate using the adhesive and to provide an additive for a laminate adhesive which has excellent solubility in an adhesive, is easily blended and achieves both content resistance (acid resistance) of an adhesive and hot water treatment.SOLUTION: There are provided: a laminate adhesive which comprises a polyol (A), a polyisocyanate (B) and an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid and a cyclic acid anhydride having an unsaturated bond; and an additive for a laminate adhesive which is an addition product of a tung oil and maleic anhydride.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a reactive urethane-based laminating adhesive containing a polyol and a polyisocyanate, and more particularly to a laminating adhesive and adhesive additive useful as packaging materials for foods, medical products, cosmetics, etc., and a laminate using the adhesive. [Background technology]

[0002] BACKGROUND ART In recent years, composites formed by multilayer lamination of metal foils such as aluminum foil or metal-deposited films with plastic films such as polyethylene, polypropylene, vinyl chloride, polyester, and nylon have been used as packaging materials for foods, medical products, cosmetics, and the like. A two-component curing adhesive containing a polyol compound and a polyisocyanate compound is preferably used as a laminating adhesive for use in such a composite film containing metal foil. Patent Documents 1 and 2, for example, describe a method for imparting content resistance (acid resistance) and hot water resistance to the two-component curing adhesive used in such a composite film containing metal foil, in order to protect the metal foil, by incorporating a resin obtained by copolymerizing a (meth)acrylic acid ester and maleic anhydride. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-184283 [Patent Document 2] Japanese Patent Publication No. 2020-109151 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the resins obtained by copolymerizing a (meth)acrylic acid ester and maleic anhydride described in Patent Documents 1 and 2 are solid at room temperature and have the problems of being difficult to dissolve in adhesives, requiring a long time for blending, resulting in poor production efficiency, and even if they do dissolve, they have the problem of being prone to precipitation when used in cold regions or during winter. Therefore, there is a limit to the amount of resin obtained by copolymerizing (meth)acrylic acid ester and maleic anhydride in an adhesive, which poses a problem in optimizing the formulation. This problem is particularly noticeable and becomes a bigger issue in solvent-free adhesives. Therefore, an object of the present invention is to provide a laminating adhesive that is easy to incorporate, has a high degree of formulation flexibility, has excellent content resistance (acid resistance), and is capable of hot water treatment, and a laminate using the adhesive. Another object of the present invention is to provide an additive for a laminating adhesive that has excellent solubility in the adhesive, is easy to incorporate, and is capable of achieving both the content resistance (acid resistance) and hot water treatment of the adhesive. [Means for solving the problem]

[0005] A laminating adhesive according to one embodiment of the present invention is characterized by comprising a polyol (A), a polyisocyanate (B), and an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid with a cyclic acid anhydride having an unsaturated bond.

[0006] A laminating adhesive according to one aspect of the present invention is characterized in that the addition product (C) has an acid value in the range of 20 mgKOH / g or more and 500 mgKOH / g or less.

[0007] A laminating adhesive according to one aspect of the present invention is characterized in that it contains the addition product (C) in an amount of 0.5 mass % or more and 10 mass % or less, based on the mass of the laminating adhesive.

[0008] A laminating adhesive according to one embodiment of the present invention is characterized in that the unsaturated fatty acid ester or unsaturated fatty acid has an iodine value, measured in accordance with JIS K0070:1992, in the range of more than 100 gI2 / 100 g and not more than 600 gI2 / 100 g.

[0009] A laminating adhesive according to one embodiment of the present invention is characterized in that the addition product (C) comprises an unsaturated fatty acid ester derived from vegetable oil or an addition product of an unsaturated fatty acid derived from vegetable oil and a cyclic acid anhydride having an unsaturated bond.

[0010] A laminating adhesive according to one embodiment of the present invention is characterized in that the vegetable oil in the vegetable oil-derived unsaturated fatty acid ester or the vegetable oil-derived unsaturated fatty acid includes at least one selected from the group consisting of tung oil and dehydrated castor oil.

[0011] A laminating adhesive according to one aspect of the present invention is characterized in that the polyol (A) and the polyisocyanate (B) are both derived from biomass.

[0012] A laminating adhesive according to one aspect of the present invention is characterized in that the addition product (C) has fluidity in a 25°C environment.

[0013] A laminating adhesive according to one aspect of the present invention is characterized in that the cyclic acid anhydride having an unsaturated bond includes at least one selected from the group consisting of maleic anhydride and itaconic anhydride.

[0014] A laminate according to one aspect of the present invention is characterized in that an adhesive layer made of the above-mentioned laminating adhesive is disposed between at least two substrates.

[0015] A laminating adhesive additive according to one aspect of the present invention is characterized in that it is an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid and a cyclic acid anhydride having an unsaturated bond.

[0016] A laminating adhesive additive according to one aspect of the present invention is characterized in that the adduct (C) is an adduct of tung oil and maleic anhydride. [Effects of the Invention]

[0017] The present invention can provide a laminating adhesive that is easy to incorporate, has a high degree of formulation flexibility, has excellent content resistance (acid resistance), and is capable of hot water treatment, as well as a laminate using the adhesive.The present invention can also provide an additive for a laminating adhesive that has excellent solubility in the adhesive, is easy to incorporate, and can achieve both the content resistance (acid resistance) and hot water treatment of the adhesive. DETAILED DESCRIPTION OF THE INVENTION

[0018] The laminating adhesive of the present invention is characterized by containing a polyol (A), a polyisocyanate (B), and an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid and a cyclic acid anhydride having an unsaturated bond. The addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid with a cyclic acid anhydride having an unsaturated bond contains an ester group derived from the unsaturated fatty acid ester or the unsaturated fatty acid and a long-chain hydrocarbon group, and therefore has excellent adhesive strength and flexibility, resulting in excellent adhesion to substrates such as plastics and metals. Furthermore, by reacting with moisture in the contents, acidic groups are generated, which prevents deterioration of adhesion to substrates such as plastics and metals over time. Due to these effects, the laminating adhesive of the present invention exhibits excellent resistance to contents, even when used as a packaging material for highly acidic contents such as vinegar, ketchup, and chili sauce. Furthermore, since the acid value of the cyclic acid anhydride is not exposed during blending, the addition product (C) can prevent hydrolysis and the promotion of the reaction between polyols and polyisocyanates. Furthermore, the unsaturated fatty acid ester or the addition product (C) of an unsaturated fatty acid with a cyclic acid anhydride having an unsaturated bond has superior solubility in polyols and / or polyisocyanates compared to a resin obtained by copolymerizing a (meth)acrylic acid ester with maleic anhydride, and therefore can be easily incorporated into adhesives and the amount incorporated can be increased, thereby increasing the degree of freedom in formulation. Furthermore, some addition products (C) are liquid at room temperature and have excellent solubility in polyols and / or polyisocyanates, which allows for easy incorporation into adhesives and greater flexibility in formulation, allowing for optimal formulation depending on the application and desired physical properties. The present invention will be described in detail below.

[0019] <Polyol (A)> The polyol (A) in the present invention is not particularly limited as long as it is a compound having two or more hydroxyl groups in the molecule. Examples of such polyols (A) include polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyvalerolactone polyols, polyolefin polyols, acrylic polyols, silicone polyols, polyhydroxyalkanes, castor oil-based polyols, and fluorine-based polyols, with polyether polyols and polyester polyols being preferred.

[0020] (Polyether polyol) The polyether polyol may be any compound having two or more hydroxyl groups and two or more ether bonds in the molecule. Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polytrimethylene glycol, polypropylene glycol, polytetramethylene glycol, and polybutylene glycol; polyethylene glycol / polypropylene glycol block copolymers; and propylene oxide / ethylene oxide random polyethers. Alternatively, an addition polymer obtained by addition polymerization of an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran to a low molecular weight polyol such as water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, or sucrose may be used as the polyether polyol. Examples of the addition polymer include propylene glycol propylene oxide adducts, glycerin propylene oxide adducts, sorbitol-based propylene oxide adducts, and sucrose-based propylene oxide adducts.

[0021] (polyester polyol) Examples of polyester polyols include polyester polyols obtained by reacting a carboxyl group component with a hydroxyl group component; and polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone). The carboxyl group component is not particularly limited as long as it is a known component, and a monofunctional carboxylic acid or a polyvalent carboxylic acid can be used. Examples of such carboxy group components include monofunctional carboxylic acids having an aromatic ring, such as benzoic acid, phenylacetic acid, and 3-phenylpropionic acid; acyclic aliphatic dicarboxylic acids, such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, and fumaric acid; alicyclic dicarboxylic acids, such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid; anhydrides or ester-forming derivatives of these aliphatic or aromatic dicarboxylic acids; and polybasic acids, such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acids.

[0022] The hydroxyl group component is not particularly limited as long as it is a known component, and examples thereof include diols and tri- or higher functional polyols. Examples of the diol include aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3,3'-dimethylolheptane, and 1,4-bis(hydroxymethyl)cyclohexane; ether glycols such as polytetramethylene ether glycol and polyoxyethylene glycol; modified polyether diols obtained by ring-opening polymerization of the aliphatic diols with various cyclic ether bond-containing compounds such as ethylene oxide and tetrahydrofuran; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic diols with various lactones such as lactanoids and ε-caprolactone; and alkylene oxide adducts of bisphenols obtained by adding ethylene oxide or the like to bisphenols such as bisphenol A and bisphenol F.

[0023] Examples of the tri- or higher functional polyols include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of the aliphatic polyols with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic polyols with various lactones such as ε-caprolactone; and castor oil-based polyols such as castor oil and castor oil derivatives.

[0024] These polyols may be modified. For example, these polyols may be a reaction product of a polyol and a polyisocyanate, in which urethane bonds have been introduced by reacting a portion of the hydroxyl groups with the polyisocyanate. Examples of the polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

[0025] For example, these polyols may be reaction products of polyols and acid anhydrides, in which carboxy groups have been introduced by reacting some of the hydroxyl groups with the acid anhydride. Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic ester anhydride. Examples of the trimellitic ester anhydride include ester compounds obtained by esterifying alkylene glycol or alkanetriol having 2 to 30 carbon atoms with trimellitic anhydride, and specific examples of the acid anhydride include ethylene glycol bisanhydrotrimellitate and propylene glycol bisanhydrotrimellitate.

[0026] The above-mentioned polyols, polyisocyanates and acid anhydrides may be used alone or in combination of two or more.

[0027] The polyol (A) may be derived from biomass, and biomass-derived polyols include polyols made from biomass-derived raw materials (for example, castor oil-based polyols). By being derived from biomass, the biomass content of the laminating adhesive can be increased, thereby reducing the burden on the environment. Among these, castor oil, castor oil derivatives, and castor oil polyols are preferably used because they are vegetable oils like the addition product (C) of the present invention and have good miscibility.

[0028] These polyols (A) may be used alone or in combination of two or more. Among them, polyols having an ester bond are preferably used to further improve the resistance to contents.

[0029] In this specification, the reaction product of a polyether polyol and a polyisocyanate may be abbreviated as polyether urethane polyol, the reaction product of a polyester polyol and a polyisocyanate as polyester urethane polyol, the reaction product of a polyether polyol and a polycarboxylic acid as polyether ester polyol, and the reaction product of a polyether ester polyol and a polyisocyanate as polyether ester urethane polyol.

[0030] <Polyisocyanate (B)> The polyisocyanate (B) in the present invention is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule. Examples of such polyisocyanates (B) include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate; 1,4-cyclohexanediisocyanate; Isocyanates, alicyclic diisocyanates such as 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane; m-phenylene diisocyanate, p- Aromatic diisocyanates such as phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate; 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate-1, Aromatic aliphatic diisocyanates such as 4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or mixtures thereof; polyisocyanate monomers such as organic triisocyanates such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene, and organic tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate;Examples of the polyisocyanates include dimers, trimers, biurets, and allophanates derived from the above diisocyanate or polyisocyanate monomers, and polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide gas and the above diisocyanate or polyisocyanate monomers.

[0031] Among these, a mixture of 4,4'-diphenylmethane diisocyanate and 2,4-diphenylmethane diisocyanate or a mixture of biuret of 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate is preferably used from the viewpoints of pot life and coating appearance, as it does not cause rapid thickening.

[0032] The polyisocyanate (B) may be an adduct (hereinafter referred to as polyurethane polyisocyanate) in which glycol is added to the above-mentioned diisocyanate or polyisocyanate monomer. Examples of the glycol include low-molecular-weight polyols having a molecular weight of less than 200, such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, and sorbitol; and polypropylene glycol, polyester polyols, polyether ester polyols, polyester amide polyols, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxy alkanes, castor oil, and polyurethane polyols, all of which have a molecular weight of 200 to 20,000. The glycols may be used alone or in combination of two or more.

[0033] The polyisocyanate (B) is preferably a polyurethane polyisocyanate, more preferably a reaction product of an aromatic polyisocyanate with a polyol, and even more preferably a reaction product of an aromatic polyisocyanate with a polyol including polypropylene glycol and a polyester polyol. The polyisocyanate (B) containing an aromatic skeleton improves heat resistance and can suppress lifting of the heat-sealed portion due to bending. The polyisocyanate (B) having a structure derived from polyester polyol further improves adhesive strength to metal-deposited films, metal foils, etc. The polyisocyanate (B) may be used alone or in combination of two or more kinds.

[0034] The polyisocyanate (B) may also be derived from biomass. Such biomass-derived polyisocyanates include polyisocyanates made from biomass-derived polyols. By being derived from biomass, the biomass content of the laminating adhesive can be increased, thereby reducing the burden on the environment.

[0035] <Addition product (C)> The addition product (C) used in the present invention is not particularly limited as long as it is a product obtained by an addition reaction of an unsaturated fatty acid ester or an unsaturated fatty acid with a cyclic acid anhydride having an unsaturated bond. The above addition reaction refers to an addition reaction of the carbon-carbon double bond of a cyclic acid anhydride having an unsaturated bond to a carbon-carbon double bond derived from an unsaturated fatty acid in an unsaturated fatty acid ester or an unsaturated fatty acid. Examples of such addition reactions include pericyclic reactions, in which the highest occupied molecular orbital (HOMO) in the π electron system of a carbon-carbon double bond interacts with the lowest unoccupied molecular orbital (LUMO) in the π electron system of an unsaturated bond to form a new σ bond in a concerted manner without going through a reaction intermediate, resulting in the production of an addition product. Typical pericyclic reactions include, but are not limited to, the ene reaction and the Diels-Alder reaction. The addition product (C) can be used alone or in combination of two or more.

[0036] Furthermore, the addition product (C) used in the present invention is preferably a compound (liquid) that exhibits fluidity in an environment of 25°C (room temperature). Preferably, the viscosity, measured with a Brookfield viscometer at 25°C, is in the range of 100 to 20,000 mPa·s, more preferably 1,000 to 18,000 mPa·s, and even more preferably 5,000 to 15,000 mPa·s. Use of such a compound provides excellent solubility in polyols and / or polyisocyanates, facilitating incorporation into adhesives and increasing formulation flexibility, allowing for the creation of an optimal formulation depending on the application and desired physical properties.

[0037] <Unsaturated fatty acid ester or unsaturated fatty acid> The unsaturated fatty acid esters include, for example, esters of glycerin and unsaturated fatty acids, and are typified by vegetable oils and fats. Examples of vegetable oils and fats include linseed oil, tung oil, mustard oil, perilla oil, perilla oil, walnut oil, sunflower oil, cottonseed oil, safflower oil, evening primrose oil, dehydrated castor oil, soybean oil, corn oil, canola oil, rice bran oil, sesame oil, almond oil, peanut oil, rosehip oil, olive oil, camellia oil, rapeseed oil, castor oil, cocoa butter, coconut oil, palm oil, macadamia nut oil, shea butter, camellia oil, avocado oil, Japan wax tree, argan oil, camellia oil, Job's tears oil, the seed oils (kernel oils) of each plant, and the fruit oils of each plant.

[0038] Vegetable oils are classified into non-drying oils with an iodine value (unit: gI2 / 100g) of 100 or less, semi-drying oils with an iodine value of over 100 but less than 130, and drying oils with an iodine value of 130 or more. The iodine value is an indicator of the number of double bonds in the oil, with a higher value indicating a higher number of double bonds. In other words, drying oils generally have many double bonds and tend to harden by oxidative polymerization with oxygen in the air. Examples of non-drying oils include olive oil, rapeseed oil, morning glory seed oil, cashew seed oil, camellia oil, castor oil, peanut oil, almond oil, coconut oil, palm oil, and cacao butter. Examples of semi-drying oils include corn oil, cottonseed oil, sesame oil, rice bran oil, and soybean oil. Examples of drying oils include tung oil, linseed oil, soybean oil, walnut oil, safflower oil, sunflower oil, perilla oil, mustard oil, evening primrose oil, perilla oil, and dehydrated castor oil.

[0039] Among vegetable oils, drying oils and semi-drying oils containing more carbon-carbon double bonds are preferred because they can add a large amount of cyclic acid anhydrides having unsaturated bonds, as described below, and improve acid resistance. Vegetable oils are more preferably those having conjugated double bonds containing cis-type double bonds in the molecule. Having at least one of the conjugated double bonds in the cis-type facilitates HOMO-LUMO interaction in the addition reaction with the cyclic acid anhydride having an unsaturated bond, and the reaction proceeds even at low temperatures, making them easy to handle. Such vegetable oils having a conjugated double bond containing a cis-type double bond in the molecule include, for example, at least one selected from the group consisting of tung oil, dehydrated castor oil, and fatty acids thereof, and are preferably used.

[0040] The unsaturated fatty acid is not particularly limited as long as it is an unsaturated fatty acid obtainable by treating the unsaturated fatty acid ester with an alkali, and examples of such unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, eicosenoic acid, erucic acid, stearidonic acid, punicic acid, palmitoleic acid, ricinoleic acid, eicosadienoic acid, docosadienoic acid, eleostearic acid, pinolenic acid, 9,11-octadecadienoic acid, and 9,12-octadecadienoic acid. As with the vegetable oils and fats described above, unsaturated fatty acids are preferably unsaturated fatty acids containing more carbon-carbon double bonds, more preferably those with an iodine value of more than 100, and even more preferably those having conjugated double bonds within the structure. Examples of the unsaturated fatty acids having an iodine value of more than 100 include linoleic acid, linolenic acid, stearidonic acid, punicic acid, eicosadienoic acid, docosadienoic acid, eleostearic acid, pinolenic acid, 9,11-octadecadienoic acid, and 9,12-octadecadienoic acid. Examples of the derivative lipid having a conjugated double bond containing a cis-type double bond include eleostearic acid and 9,11-octadecadienoic acid.

[0041] The iodine value can be measured in accordance with JIS K0070: 1992. The iodine value of the unsaturated fatty acid ester or unsaturated fatty acid is preferably in the range of more than 100 gI2 / 100 g to 600 gI2 / 100 g or less, more preferably in the range of more than 100 gI2 / 100 g to 300 gI2 / 100 g or less.

[0042] <Cyclic acid anhydride having an unsaturated bond> The cyclic acid anhydride having an unsaturated bond is not particularly limited as long as it has an anhydride ring in the molecule and an unsaturated bond, and the unsaturated bond may be a part of the anhydride ring. Examples of such cyclic acid anhydrides having an unsaturated bond include maleic anhydride, exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, itaconic anhydride, 2-dodecen-1-ylsuccinic anhydride, 2-octenylsuccinic anhydride, decenylsuccinic anhydride, hexadecenylsuccinic anhydride, 2-hexen-1-ylsuccinic anhydride, bicyclo[2.2.1]hept-5-ene-exo-2,3-dicarboxylic anhydride, and 2,3-diphenylmaleic anhydride. Anhydride, 4-cyclohexene-1,2-dicarboxylic acid anhydride, (2,7-octadien-1-yl)succinic anhydride, 2-buten-1-ylsuccinic anhydride, phenylmaleic anhydride, citraconic anhydride, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, methylcyclohexene-1,2-dicarboxylic acid anhydride, (methyl)nadic anhydride, allylsuccinic anhydride, 3 (or 4)-methyl-1,2,3,6-tetrahydrophthalic anhydride. Preferably, it is at least one selected from the group consisting of maleic anhydride, itaconic anhydride, (methyl)nadic anhydride, and 4-cyclohexene-1,2-dicarboxylic anhydride. Among these, maleic anhydride and itaconic anhydride are preferably used because the addition reaction with the unsaturated fatty acid ester or unsaturated fatty acid proceeds easily and the resulting addition product (C) can maintain fluidity at room temperature.

[0043] The acid value of the addition product (C) is preferably in the range of 20 mgKOH / g or more and 500 mgKOH / g or less. When the acid value is 20 mgKOH / g or more, excellent resistance to contents and hot water is exhibited even when the amount of the addition product (C) is small, which is preferable. When the acid value is 500 mgKOH / g or less, moisture absorption, which is a cause of deterioration after the adhesive has hardened, is suppressed, which is preferable. The acid value is more preferably in the range of 40 mgKOH / g or more and 400 mgKOH / g or less. Even more preferably, the acid value is in the range of 100 mgKOH / g or more and 300 mgKOH / g or less.

[0044] In the laminating adhesive of the present invention, the blending ratio of polyol (A) to polyisocyanate (B) is not particularly limited and may be appropriately set depending on the application and required performance. The molar equivalent ratio [OH / NCO] of the hydroxyl groups in polyol (A) to the isocyanato groups in polyisocyanate (B) is preferably in the range of 1.0 to 10.0, more preferably 1.5 to 4.0. The above range is preferred from the viewpoints of suppressing residual isocyanate, curing speed, and formation of a cured film.

[0045] The laminating adhesive of the present invention preferably contains the addition product (C) in the range of 0.5 to 10 mass % based on the mass of the adhesive. A content of 10 mass % or less is preferred because urethane curing defects do not occur. A content of 0.5 mass % or more is preferred because the effects of the addition product (C) are fully exhibited. A content of 2 to 7 mass % is more preferred.

[0046] Of the above-mentioned addition products (C), the addition product of tung oil and maleic anhydride in particular is liquid at room temperature, has a high acid value, and undergoes reaction at low temperatures. Therefore, it exhibits excellent handling properties and resistance to contents, and can be suitably used as an additive for laminating adhesives.

[0047] <Other ingredients> The laminating adhesive of the present invention may further contain additives such as antioxidants, UV absorbers, hydrolysis inhibitors, antifungals, thickeners, plasticizers, defoamers, pigments, and fillers as needed. To further enhance adhesive performance, the adhesive may also contain adhesion aids such as silane coupling agents, phosphoric acid, phosphoric acid derivatives, acid anhydrides, and adhesive resins. It may also contain known catalysts and additives to regulate the curing reaction. These other components may be used singly or in combination of two or more.

[0048] <Laminate> The laminate of the present invention is a laminate in which an adhesive layer made of a laminating adhesive comprising a mixture of polyol (A), polyisocyanate (B), and addition product (C) is laminated between at least two substrates. The laminate can be formed, for example, by applying the laminating adhesive to a first substrate, laminating a second substrate thereto, and curing the adhesive layer located between the two substrates at room temperature or under elevated temperature, but is not limited to this configuration. The laminate of the present invention may further comprise another layer disposed thereon via an adhesive layer or the like. When the laminate of the present invention is a laminate comprising three or more substrate layers, the adhesive layer can also be suitably used as an outer layer that is less susceptible to the effects of the contents. The amount of adhesive to be applied is selected appropriately depending on the type of substrate and coating conditions, but is usually 1.0 to 5.0 g / m 2 and preferably 1.5 to 4.5 g / m 2 is. The thickness of the laminate is preferably 10 μm or more from the viewpoint of strength and durability as a packaging material.

[0049] [Base material] The substrate is not particularly limited, and examples thereof include plastic films, paper, gas barrier substrates, sealants, etc., which are commonly used in packaging applications, and the two substrates may be the same or different types. Examples of plastic films that can be used include polyester resin films such as polyethylene terephthalate, polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resin films such as polyethylene (PE) and polypropylene (PP); polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; and multilayer films and mixtures thereof (e.g., nylon 6 / MXD6 / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6). Among these, films having mechanical strength and dimensional stability are preferred. The plastic film preferably has a thickness of 5 to 50 μm, more preferably 10 to 30 μm.

[0050] Examples of paper include natural paper and synthetic paper. As the gas barrier substrate, aluminum foil and plastic films having a vapor-deposited layer of aluminum, silica, alumina, etc. are preferred. For example, in the case of aluminum foil, a thickness in the range of 3 to 50 μm is preferred from an economical point of view.

[0051] Examples of sealants include polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and polyolefin resins such as ionomers. Among these, polypropylene-based resins are preferred from the viewpoint of heat resistance during retort, and unstretched polypropylene is particularly preferred from the viewpoint of heat-sealability. The thickness of the sealant is not particularly limited, but is preferably in the range of 10 to 60 μm, more preferably 15 to 40 μm, taking into consideration processability into packaging, heat sealing properties, etc. Furthermore, by providing the sealant with unevenness with a height difference of 5 to 20 μm, it is possible to impart slip properties to the sealant and tearability to the packaging. Furthermore, the various sealants may have a vapor-deposited layer of aluminum, silica, alumina, etc. in addition to the aluminum foil.

[0052] The substrate may have a printed layer thereon. The printed layer is a layer on which any desired printed pattern such as letters, numbers, pictures, figures, symbols, or designs is formed for decoration, indication of contents, expiration date, manufacturer, seller, or other indication or aesthetic purposes, and includes a solid printed layer. The printed layer can be formed using conventionally known pigments or dyes, and the method for forming the printed layer is not particularly limited. Generally, the printed layer is formed using a printing ink containing a colorant such as a pigment or dye. The method for applying the printing ink is not particularly limited, and the printing ink can be applied by methods such as gravure coating, flexo coating, roll coating, bar coating, die coating, curtain coating, spin coating, and inkjet coating. The printed layer can be formed by leaving the ink to stand, or, if necessary, subjecting the ink to air blowing, heating, drying under reduced pressure, or ultraviolet irradiation. The printing layer preferably has a thickness of 0.1 to 10 μm, more preferably 1 to 5 μm, and even more preferably 1 to 3 μm. [Example]

[0053] The present invention will be described in more detail below with reference to examples and comparative examples. In the examples and comparative examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[0054] <Number average molecular weight (Mn)> The number average molecular weight (Mn) of the polyol was calculated using gel permeation chromatography (GPC) in terms of standard polystyrene.

[0055] <Production of Polyol (A)> (Synthesis example a-1) A reaction vessel was charged with 30 parts of a triol with a molecular weight of approximately 400, in which polypropylene glycol was added to glycerin, 30 parts of polypropylene glycol with a molecular weight of approximately 400, 20 parts of polypropylene glycol with a molecular weight of approximately 2,000, and 20 parts of 4,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, yielding polyol (a-1), a polyether urethane polyol with a viscosity of 6,000 mPa·s and hydroxyl groups at both ends.

[0056] (Synthesis example a-2) A reaction vessel was charged with 20 parts of a triol with a molecular weight of approximately 400, made by adding polypropylene glycol to glycerin, 40 parts of polypropylene glycol with a molecular weight of approximately 400, 20 parts of polypropylene glycol with a molecular weight of approximately 2,000, 10 parts of a polyester polyol with a molecular weight of approximately 2,000, whose main components are adipic acid and propylene glycol, and 10 parts of 4,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, yielding polyol (a-2), a polyether ester urethane polyol with a viscosity of 4,000 mPa·s and hydroxyl groups at both ends.

[0057] (Synthesis example a-3) A reaction vessel was charged with 90 parts of a polyester polyol (manufactured by ADEKA Corporation, product name: ADEKA New Ace F7-67) with a molecular weight of approximately 2,000, primarily composed of adipic acid and propylene glycol, and 10 parts of propylene glycol. The mixture was heated to 80°C for 2 hours while stirring under a nitrogen gas stream to dissolve, yielding polyol (a-3), a polyetherester polyol with hydroxyl groups at both ends and a viscosity of 5,500 mPa s.

[0058] (Synthesis example a-4) A reaction vessel was charged with 20 parts of a triol (approximately 400 molecular weight) made by the addition of polypropylene glycol to glycerin, 40 parts of castor oil polyol (Toyokuni Oil Mills, product name: HS 2G-270B), 20 parts of polypropylene glycol (approximately 2,000 molecular weight), 10 parts of a polyester polyol (approximately 2,000 molecular weight) composed primarily of adipic acid and propylene glycol, and 10 parts of 4,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours with stirring under a nitrogen gas stream to carry out a urethane reaction, yielding polyol (a-4), a polyetherester urethane polyol with a viscosity of 3,500 mPa·s and hydroxyl groups at both ends.

[0059] (Synthesis example a-5) A reaction vessel was charged with 3 parts of a triol with a molecular weight of approximately 400, made by adding polypropylene glycol to glycerin, 36 parts of polypropylene glycol with a molecular weight of approximately 400, 10 parts of polypropylene glycol with a molecular weight of approximately 2,000, 11 parts of 4,4'-diphenylmethane diisocyanate, 10 parts of toluene diisocyanate, and 30 parts of ethyl acetate. The mixture was heated at 80-90°C for 5 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, yielding a solution of polyol (a-5), a polyether urethane polyol with hydroxyl groups at both ends, with a viscosity of 6,000 mPa·s.

[0060] (Synthesis example a-6) A reaction vessel was charged with 35 parts of adipic acid, 33 parts of isophthalic acid, and 33 parts of ethylene glycol. The mixture was heated at 220-230°C for 4 hours while stirring under a nitrogen gas stream to carry out a dehydration reaction, and then the pressure was reduced to 20 torr to carry out a deglycolization reaction. Finally, ethyl acetate was added to obtain a polyester solution with a solids content of 80%, a molecular weight of 2,500, and a viscosity of 2,500 mPa·s. 70 parts of the resulting polyester solution (solid content 80%), 4 parts of toluene diisocyanate, and 26 parts of ethyl acetate were placed in a reaction vessel. The mixture was heated at 80-90°C for 5 hours with stirring under a nitrogen gas stream to carry out a urethane reaction, yielding a solution of polyol (a-6), a polyester urethane polyol with hydroxyl groups at both ends and a viscosity of 2,000 mPa·s.

[0061] The polyols (A) obtained are listed in Table 1.

[0062] [Table 1]

[0063] The abbreviations in Table 1 are as follows: Castor oil polyol: Toyokuni Oil Mills, product name: HS 2G-270B PPG400 (3f): A triol with a molecular weight of approximately 400, in which polypropylene glycol is added to glycerin (manufactured by ADEKA Corporation, product name: ADEKA Polyether G-400) PPG400(2f): Polypropylene glycol with a molecular weight of approximately 400 (manufactured by ADEKA Corporation, trade name: ADEKA Polyether P-400) PPG2000: Polypropylene glycol with a molecular weight of approximately 2,000 (manufactured by ADEKA Corporation, product name: ADEKA Polyether P-2000) 1,2-PG / AdA: A polyester polyol with a molecular weight of approximately 2,000, primarily composed of adipic acid and propylene glycol (manufactured by ADEKA Corporation, product name: ADEKA New Ace F7-67) 1,2-PG: propylene glycol 4,4′-MDI: 4,4′-diphenylmethane diisocyanate TDI: Toluene diisocyanate

[0064] <Production of Polyisocyanate (B)> (Synthesis example b-1) A reaction vessel was charged with 5 parts of a triol with a molecular weight of approximately 400, in which polypropylene glycol was added to glycerin, 5 parts of polypropylene glycol with a molecular weight of approximately 400, 30 parts of polypropylene glycol with a molecular weight of approximately 2,000, 30 parts of 4,4'-diphenylmethane diisocyanate, and 30 parts of 2,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, yielding polyisocyanate (b-1), a polyether urethane polyisocyanate with isocyanato groups at both ends and with a viscosity of 5,000 mPa·s.

[0065] (Synthesis example b-2) A reaction vessel was charged with 10 parts of a triol with a molecular weight of approximately 400, made by adding polypropylene glycol to glycerin, 10 parts of polypropylene glycol with a molecular weight of approximately 400, 20 parts of polypropylene glycol with a molecular weight of approximately 2,000, 10 parts of a polyester polyol with a molecular weight of approximately 2,000, primarily composed of adipic acid and propylene glycol, 25 parts of 4,4'-diphenylmethane diisocyanate, and 25 parts of 2,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours with stirring under a nitrogen gas stream to carry out a urethane reaction, yielding polyisocyanate (b-2), a polyetherester urethane polyisocyanate with isocyanato groups at both ends and with a viscosity of 10,000 mPa·s.

[0066] (Synthesis example b-3) A reaction vessel was charged with 10 parts of a triol (approximately 400 molecular weight) made by the addition of polypropylene glycol to glycerin, 10 parts of castor oil polyol (Toyokuni Oil Mills, product name: HS 2G-270B), 20 parts of polypropylene glycol (approximately 2,000 molecular weight), 10 parts of a polyester polyol (approximately 2,000 molecular weight) composed primarily of adipic acid and propylene glycol, 25 parts of 4,4'-diphenylmethane diisocyanate, and 25 parts of 2,4'-diphenylmethane diisocyanate. The mixture was heated at 80-90°C for 4 hours with stirring under a nitrogen gas stream to carry out the urethane reaction, yielding polyisocyanate (b-3), a polyetherester urethane polyisocyanate with isocyanato groups at both ends and with a viscosity of 7,000 mPa·s.

[0067] (Synthesis example b-4) A reaction vessel was charged with 3 parts of a triol with a molecular weight of approximately 400, in which polypropylene glycol was added to glycerin, 9 parts of polypropylene glycol with a molecular weight of approximately 400, 40 parts of polypropylene glycol with a molecular weight of approximately 2,000, 23 parts of 4,4'-diphenylmethane diisocyanate, and 25 parts of ethyl acetate. The mixture was heated at 80-90°C for 5 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, yielding a solution of polyisocyanate (b-4), a polyether urethane polyisocyanate with isocyanato groups at both ends, with a viscosity of 3,000 mPa·s.

[0068] (Synthesis example b-5) 70 parts of a TMP adduct solution of toluene diisocyanate (solid content 75%) and 30 parts of ethyl acetate were charged into a reaction vessel. The mixture was stirred under a nitrogen gas stream to obtain a solution of polyisocyanate (b-5), which was a TMP adduct solution of toluene diisocyanate (solid content 52.5%) with a viscosity of 20 mPa s.

[0069] The polyisocyanates (B) obtained are listed in Table 2.

[0070] [Table 2]

[0071] The abbreviations in Table 2 are as follows: Castor oil polyol: Toyokuni Oil Mills, product name: HS 2G-270B PPG400 (3f): A triol with a molecular weight of approximately 400, in which polypropylene glycol is added to glycerin (manufactured by ADEKA Corporation, product name: ADEKA Polyether G-400) PPG400(2f): Polypropylene glycol with a molecular weight of approximately 400 (manufactured by ADEKA Corporation, trade name: ADEKA Polyether P-400) PPG2000: Polypropylene glycol with a molecular weight of approximately 2,000 (manufactured by ADEKA Corporation, product name: ADEKA Polyether P-2000) 1,2-PG / AdA: A polyester polyol with a molecular weight of approximately 2000, primarily composed of adipic acid and propylene glycol (manufactured by ADEKA Corporation, product name: ADEKA New Ace F7-67) 4,4′-MDI: 4,4′-diphenylmethane diisocyanate 2,4'-MDI: 2,4'-diphenylmethane diisocyanate TDI TMP adduct: TMP adduct solution of toluene diisocyanate (solid content 75%)

[0072] <Production of Addition Product (C)> (Synthesis Example c-1 (Example c-1)) 100 parts of tung oil and 21.9 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 110-120°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-1) with an acid value of 205.5 mg KOH / g.

[0073] (Synthesis example c-2) 100 parts of tung oil and 25.2 parts of a commercially available additive 1 (manufactured by New Japan Chemical Co., Ltd., trade name: Rikacid OSA, acid value: 530 mg KOH / g) were charged into a reaction vessel. The mixture was heated at 120 to 130°C for 5 hours with stirring under a nitrogen gas flow, yielding an addition product (c-2) with an acid value of 170.8 mg KOH / g.

[0074] (Synthesis example c-3) 100 parts of tung oil and 36.9 parts of nadic anhydride were charged into a reaction vessel. The mixture was heated at 110-120°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-3) with an acid value of 184.0 mgKOH / g.

[0075] (Synthesis example c-4) 100 parts of linseed oil and 21 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 200°C to 210°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-4) with an acid value of 198.5 mg KOH / g.

[0076] (Synthesis example c-5) 100 parts of sesame oil and 12.9 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 200 to 210°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-5) with an acid value of 130.7 mg KOH / g.

[0077] (Synthesis example c-6) 100 parts of palm oil and 5.7 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 200 to 210°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-6) with an acid value of 61.7 mg KOH / g.

[0078] (Synthesis example c-7) 100 parts of cacao butter and 3.6 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 200 to 210°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-7) with an acid value of 39.7 mg KOH / g.

[0079] (Synthesis example c-8) 100 parts of coconut oil and 1.2 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 200 to 210°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-8) with an acid value of 13.6 mg KOH / g.

[0080] (Synthesis Example c-9 (Example c-9)) 100 parts of tung oil and 3.7 parts of maleic anhydride were charged into a reaction vessel. The mixture was heated at 110-120°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-9) with an acid value of 40.3 mg KOH / g.

[0081] (Synthesis Example c-10 (Example c-10)) 100 parts of tung oil and 1 part of maleic anhydride were charged into a reaction vessel. The mixture was heated at 110-120°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-10) with an acid value of 16.5 mg KOH / g.

[0082] (Synthesis example c-11) 100 parts of tung oil and 34.5 parts of crotonic anhydride were charged into a reaction vessel. The mixture was heated at 120-130°C for 5 hours while stirring under a nitrogen gas flow, yielding an addition product (c-11) with an acid value of 186.6 mg KOH / g.

[0083] The resulting addition products (C) are listed in Table 3.

[0084] [Table 3]

[0085] The abbreviations in Table 3 are as follows: Commercially available additive 1: low molecular weight cyclic acid anhydride having an unsaturated bond (manufactured by New Japan Chemical Co., Ltd., trade name: Rikacid OSA, acid value: 530 mg KOH / g)

[0086] <Synthesis of (meth)acrylic acid ester-maleic anhydride copolymer (MMA / MAH)> A reaction vessel equipped with a stirrer, temperature control system, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 200 parts of toluene, and the temperature was raised to 110°C while stirring and introducing nitrogen gas. Next, dropping tank 1 was charged with 80 parts of methyl methacrylate, 50 parts of butyl acrylate, 100 parts of maleic anhydride, and 50 parts of toluene, and dropping tank 2 was charged with a solution of 9 parts of benzoyl peroxide in 50 parts of toluene. These were simultaneously added dropwise over 2 hours with stirring while maintaining the temperature inside the reaction vessel at 110°C. After the reaction was completed, the mixture was cooled to room temperature, and the polymer was precipitated with a large amount of methanol, filtered, and dried at 120°C for 6 hours to obtain a (meth)acrylic acid ester-maleic anhydride copolymer with a number average molecular weight of 10,000 and an acid value of 460 mgKOH / g.

[0087] <Laminating adhesive manufacturing> [Examples 1 to 22, Comparative Examples 1 to 11] The obtained polyol (A), polyisocyanate (B), and addition product (C) were mixed in the formulation shown in Tables 4 and 5 to obtain adhesives. Examples 1 to 4 and 7 to 22 and Comparative Examples 1 to 4 and 7 to 11 are solvent-free adhesives, and Examples 5 and 6 and Comparative Examples 5 and 6 are solvent-based adhesives.

[0088] <Evaluation of laminating adhesives> The resulting laminating adhesive was used to prepare a laminate, which was then evaluated as follows. The results are shown in Tables 4 and 5.

[0089] [Laminate fabrication] A 12 μm thick polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E5100) was prepared. Next, a polyester-type dry laminating adhesive (manufactured by Toyo-Morton Co., Ltd., product name: TM-250HV / CAT-RT86L-60) was adjusted to a solid content of 30% and applied to the polyethylene terephthalate film using a dry laminator. The adhesive was applied in an amount of 3.5 g / m. 2 Next, an aluminum (AL) foil (manufactured by Toyo Aluminum K.K., trade name: Aluminum Haku C) having a thickness of 9 μm was attached to obtain a laminated film. The laminating adhesive obtained in the Examples and Comparative Examples was applied to the aluminum foil surface of the obtained laminate film, and a 50 μm thick unstretched polyethylene (PE) film (manufactured by Mitsui Chemicals Tocello Co., Ltd., product name: TUX-FCD) was laminated thereon. If the laminating adhesive is a solvent-free type, adjust the temperature of the adhesive to 70°C and apply a coating amount of 2.0 g / m using a solvent-free test coater. 2 When the laminating adhesive is solvent-based, the adhesive is adjusted to a solid content of 30% and applied at a rate of 3.5 g / m using a dry laminator. 2 It was applied with. The obtained laminate was placed in a thermostatic chamber at 40°C for 4 days to cure the adhesive, thereby obtaining a laminate for evaluation. The obtained laminate was used to evaluate adhesive strength and ketchup resistance.

[0090] [Normal adhesive strength] A test piece 300 mm long and 15 mm wide was cut from the laminate in the MD direction. Using an Instron tensile tester, the AL / PE T-peel strength (N / 15 mm) was measured at a peel rate of 300 mm / min. This test was performed five times, and the average value was calculated.

[0091] [Ketchup resistant (hot and water resistant)] A 120 mm long, 90 mm wide piece was cut from the laminate in the MD direction, folded in the TD direction so that the polyethylene surface was on the inside, and heat-sealed at three locations at 190°C over 5 mm of the edge to create a 60 mm long, 90 mm wide bag. 20 g of ketchup was enclosed inside the bag. The resulting bag was boiled at 98°C for 30 minutes, and the contents were removed. Using the laminate, the average T-peel strength (N / 15 mm) between the AL and PE was calculated using the same method as above. The percentage change from the average value in the normal state was calculated and evaluated according to the following criteria. ◎: Change rate is less than 20% (very good) ○: Change rate is 20% or more but less than 50% (good) △: Change rate is 50% or more but less than 80% (usable) ×: Change rate is 80% or more (unusable)

[0092] [Ketchup resistance (bending resistance)] A 100 mm long, 100 mm wide piece was cut from the laminate in the MD direction, folded in the TD direction and then the MD direction so that the polyethylene surface was facing outward, and secured with clips to prepare a test specimen. A 60 mm diameter transparent glass bottle was prepared in advance, filled with ketchup to a liquid level of 70 mm. The resulting test specimen was placed in the bottle, sealed, and left to stand at 40°C for one week. After one week, the test specimen was removed and observed for delamination between the AL and PE at the cross folds and the mountain and valley folds of the test specimen. The size of the delamination was visually observed and evaluated according to the following criteria. ◎: No delamination was observed on the test piece (very good) ○: Delamination was observed only at the apex of the cross fold (good) △: Delamination was observed at the mountain fold or valley fold (usable) ×: Delamination observed at places other than the fold (unusable)

[0093] [Ketchup resistance (resistance to contents)] A 120 mm long, 90 mm wide piece was cut from the laminate in the MD direction, folded in the TD direction so that the polyethylene surface was on the inside, and three 5 mm portions of the edge were heat-sealed at 190°C to create a 60 mm long, 90 mm wide bag. 20 g of ketchup was enclosed inside the bag. The resulting bag was aged at 40°C for one month. After one month, the contents were removed from the laminate, and the average T-peel strength (N / 15 mm) between the AL and PE was calculated using the same method as above. The percentage change from the average value in the normal state was calculated and evaluated according to the following criteria. ◎: Change rate less than 50% (very good) ○: Change rate is 50% or more but less than 70% (good) △: Change rate is 70% or more but less than 90% (usable) ×: Change rate is 90% or more (unusable)

[0094] [Table 4]

[0095] [Table 5]

[0096] The abbreviations in Tables 4 and 5 are as follows: Commercially available additive 1: low molecular weight cyclic acid anhydride (manufactured by New Japan Chemical Co., Ltd., product name: Rikacid OSA, acid value: 530 mg KOH / g) Commercially available additive 2: Maleic anhydride adduct of fatty acid from dehydrated castor oil (main component: octadecadienoic acid) (manufactured by Ito Oil Mills, trade name: HIMALEIN DF-20, acid value: 260.1 mg KOH / g)

[0097] Tables 4 and 5 show that the laminating adhesive of the present invention, which contains the addition product (C) of an unsaturated fatty acid ester or unsaturated fatty acid (c1) with a cyclic acid anhydride (c2) having an unsaturated bond, exhibited excellent resistance to contents even when used as a packaging material for highly acidic contents such as ketchup. Furthermore, the addition product (C) has excellent solubility in the adhesive, making it not only easy to incorporate, but also able to dissolve in the adhesive and be used even when the amount incorporated was increased.

Claims

1. A laminating adhesive comprising a polyol (A), a polyisocyanate (B), and an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid with a cyclic acid anhydride having an unsaturated bond, wherein the addition product (C) comprises an addition product of an unsaturated fatty acid ester derived from vegetable oil or an unsaturated fatty acid derived from vegetable oil with a cyclic acid anhydride having an unsaturated bond.

2. 2. The laminating adhesive according to claim 1, wherein the addition product (C) has an acid value in the range of 20 mg KOH / g or more and 500 mg KOH / g or less.

3. The laminating adhesive according to claim 1 or 2, comprising the addition product (C) in an amount of 0.5 mass % or more and 10 mass % or less, based on the mass of the laminating adhesive.

4. The unsaturated fatty acid ester or unsaturated fatty acid has an iodine value of 100 g / L as measured in accordance with JIS K0070:1992. ２ / 100g or more, 600gI ２ The laminating adhesive according to any one of claims 1 to 3, wherein the laminating adhesive has a viscosity of 1000 psi or less.

5. The laminating adhesive according to any one of claims 1 to 4, wherein the vegetable oil in the vegetable oil-derived unsaturated fatty acid ester or the vegetable oil-derived unsaturated fatty acid comprises at least one selected from the group consisting of tung oil and dehydrated castor oil.

6. The laminating adhesive according to any one of claims 1 to 5, wherein the polyol (A) and the polyisocyanate (B) are both derived from biomass.

7. The laminating adhesive according to any one of claims 1 to 6, wherein the addition product (C) has fluidity in an environment of 25°C.

8. The laminating adhesive according to any one of claims 1 to 7, wherein the cyclic acid anhydride having an unsaturated bond comprises at least one selected from the group consisting of maleic anhydride and itaconic anhydride.

9. A laminate comprising an adhesive layer made of the laminating adhesive according to any one of claims 1 to 8 disposed between at least two substrates.

10. An additive for laminate adhesives, which is an addition product (C) of an unsaturated fatty acid ester or an unsaturated fatty acid and a cyclic acid anhydride having an unsaturated bond, wherein the addition product (C) comprises an addition product of an unsaturated fatty acid ester derived from vegetable oil or an unsaturated fatty acid derived from vegetable oil and a cyclic acid anhydride having an unsaturated bond.

11. 11. The laminating adhesive additive according to claim 10, wherein the adduct (C) is an adduct of tung oil and maleic anhydride.

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