Reactive adhesives, laminates and packaging

Abstract

The present invention provides a reactive adhesive capable of forming a packaging body that does not delamination even when filled with highly acidic or oily foods and subjected to high-temperature retorting, as well as a laminate and packaging body made using the adhesive. [Solution] The above problem is solved by a reactive adhesive comprising a main component and a curing agent, wherein the main component comprises a polyester urethane polyol (A) having constituent units derived from a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups each in one molecule, and the curing agent comprises a polyisocyanate (B).

Description

Technical Field

[0001] The present invention relates to an adhesive having an excellent adhesive function, which is suitably used when manufacturing a laminated body for packaging foods, medical products, cosmetics, etc. by laminating a plurality of various plastic films, metal vapor deposition films or metal foils. Further, the present invention relates to a laminated body for packaging used for packaging foods, medical products, cosmetics, etc.

Background Art

[0002] In recent years, as packaging materials for foods, medical products, cosmetics, etc., those obtained by multilayer laminating and compounding a metal foil such as an aluminum foil or a metal vapor deposition film and a plastic film such as polyethylene, polypropylene, vinyl chloride, polyester, nylon, etc. are used. The applications of these composite films obtained by bonding a plastic film and a metal foil or a metal vapor deposition film together are often used in fields where resistance is required under severe conditions, such as packaging bags for heavy items such as bottled and tubed products, and packaging bags for hot water boiling and retort processing for the purpose of cooking and sterilization. Sufficient adhesiveness (lamination strength) between the films and strength of the bag-making part (seal strength) are required, and further water resistance and oil resistance (boiling and retort suitability) at high temperatures are required. Particularly in packaging bags, from the viewpoints of space saving and maintaining hygiene, the demand for a shape in which a composite film is adhered in accordance with the shape of food is increasing. Along with this, the composite film is required to have flexibility and boil and retort resistance in an environment where it is bent and distorted.

[0003] Conventionally, in response to such requirements, studies have been made to improve the adhesive force to a metal foil or a metal vapor deposition film and heat resistance by adding an epoxy-based silane coupling agent to a laminate adhesive. However, in recent years, restrictions on the amount of migration of epoxy-based silane coupling agents to foods are becoming stricter, especially in Europe. Therefore, there is a desire for a reactive adhesive in which the coupling agent is reduced or removed and the adhesion to metal is improved by other means.

[0004] On the other hand, a known method for improving adhesion to aluminum foil and metal vapor-deposited surfaces without using GLYMO is to increase the acid value using an acid modifier. For example, Patent Document 1 describes that adhesion to metal foil or metal vapor-deposited film can be improved by using a partially acid-modified polyol obtained by reacting trimellitic anhydride or trimellitic anhydride ester with polyester polyurethane polyol.

[0005] Patent Document 2 describes a dry laminating adhesive composition containing a polyol component and a polyisocyanate component, in which a hydroxycarboxylic acid having a number average molecular weight of 200 to 5,000, an acid value of 20 to 350, and a hydroxyl value of 20 to 350 is included as part of the polyol component in an amount such that the acid value derived from the hydroxycarboxylic acid as a percentage of the acid value of the solid content of the adhesive composition is 1 to 20, thereby improving adhesion to metal foil films and vapor-deposited films. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-132902 [Patent Document 2] Japanese Patent Application Publication No. 08-183943 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, while the adhesive described in Patent Document 1 exhibits good adhesion in boiling and retorting at moderate temperatures (~120°C), in high-temperature retorting (120°C~135°C), adhesion may be insufficient and peel off depending on the contents and substrate. For example, packaging bags made using a general composite film consisting of polyester or nylon film / aluminum foil / unstretched polypropylene film lamination have the problem of delamination (peeling) of the heat-sealed portion occurring immediately after retorting and over time. Furthermore, the adhesive described in Patent Document 2, like that described in Patent Document 1, has the problem of delamination occurring at the heat-sealed portion in high-temperature retort environments.

[0008] This invention has been made in view of the above background, and aims to provide a reactive adhesive capable of forming a packaging body that does not delamination even when filled with highly acidic or oily foods and subjected to high-temperature retorting, as well as a laminate and packaging body made using the adhesive. [Means for solving the problem]

[0009] <1> The present invention relates to a reactive adhesive comprising a main component and a curing agent, wherein the main component comprises a polyester urethane polyol (A) having constituent units derived from a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups each in one molecule, and the curing agent comprises a polyisocyanate (B).

[0010] <2> The present invention relates to a compound in which the hydroxycarboxylic acid (a1) has two hydroxyl groups and two carboxyl groups in one molecule. <1> Regarding the reactive adhesive described.

[0011] <3> The present invention relates to a case where the hydroxycarboxylic acid (a1) is tartaric acid. <1> or <2> Regarding the reactive adhesive described.

[0012] <4> The present invention relates to a polyester urethane polyol (A) which is a reaction product of a polyester polyol, a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule, and a polyisocyanate, wherein the amount of the hydroxycarboxylic acid (a1) is 0.1 to 3.0% by mass based on the mass of the polyester polyol. <1> ~ <3> This relates to reactive adhesives as described in any one of the items.

[0013] <5> The present invention relates to a polyester urethane polyol (A) having at least one constituent unit selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxyl groups in one molecule, at its molecular terminus. <1> ~ <4> This relates to reactive adhesives as described in any one of the items.

[0014] <6> The present invention relates to a reaction product of a polyester urethane polyol (A) being a reaction product of a polyester polyol, a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and two or more carboxyl groups in one molecule, a polyisocyanate, and a compound selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxyl groups in one molecule, wherein the total amount of (c1) and (c2) being blended is 0.1 to 2.0% by mass, based on the mass of the polyester polyol. <1> ~ <5> This relates to reactive adhesives as described in any one of the items.

[0015] <7> The present invention relates to a polyisocyanate (B) comprising at least one selected from the group consisting of reaction products of isophorone diisocyanate and trimethylolpropane, and reaction products of xylylene diisocyanate and trimethylolpropane. <1> ~ <6> This relates to reactive adhesives as described in any one of the items.

[0016] <8> The present invention relates to a polyisocyanate (B) comprising the reaction product of isophorone diisocyanate and trimethylolpropane, and the reaction product of xylylene diisocyanate and trimethylolpropane. <1> ~ <7> This relates to reactive adhesives as described in any one of the items.

[0017] <9>The present invention relates to the reactive adhesive according to any one of <1> to <8>, wherein the number concentration of particles having a particle diameter of 25 μm or more based on the solid content mass, which is calculated based on the measurement of the number concentration of particles using the dynamic light scattering method shown below, is 4000 particles / mL or less. <Method for measuring the number concentration of particles having a particle diameter of 25 μm or more> Using a dynamic light scattering fine particle automatic measurement system, measure the particle diameter and the number concentration of insoluble fine particles (particles / mL) in the diluted main agent solution. Next, from the obtained histogram (vertical axis: number concentration of particles (particles / mL), horizontal axis: particle diameter), calculate the number concentration of particles having a particle diameter of 25 μm or more (particles / mL). The measurement is performed three times, and using the obtained values, calculate the number concentration of particles having a particle diameter of 25 μm or more based on the solid content mass according to the following formula. Formula) Particle number concentration = [{Σ(a1 + a2 + a3) / 3 × n] - {b × (n - 1)}] × (X / 100) - c × (100 - X / 100) [In the above formula, X: Solid content concentration of the main agent before dilution (mass%) a1: Number concentration of particles having a particle diameter of 25 μm or more in the first measurement (particles / mL) a2: Number concentration of particles having a particle diameter of 25 μm or more in the second measurement (particles / mL) a3: Number concentration of particles having a particle diameter of 25 μm or more in the third measurement (particles / mL) b: Number concentration of particles having a particle diameter of 25 μm or more in the dilution solvent (particles / mL) c: Number concentration of particles having a particle diameter of 25 μm or more in the added solvent during synthesis (particles / mL) n: Dilution ratio (times) is)

[0018] <10>The present invention relates to the reactive adhesive according to any one of <1> to <9>, wherein the content of the silane coupling agent contained in the reactive adhesive is 0.1 mass% or less based on the mass of the polyester urethane polyol (A).

[0019] <11>The present invention relates to a laminate having an adhesive layer formed from the reactive adhesive according to any one of <1> to <10> between a first substrate and a second substrate.

[0020] <12>The present invention relates to a package using the laminate described in <11>.

Effects of the Invention

[0021] According to the present invention, even when a food with a high acidity or an oily food is filled as a content and retorting in a high temperature range is performed, a reactive adhesive capable of forming a package in which delamination does not occur, and a laminate and a package in which delamination does not occur even when a food with a high acidity or an oily food is filled as a content and retorting in a high temperature range can be provided.

Embodiments for Carrying Out the Invention

[0022] <<Reactive Adhesive>> The reactive adhesive of the present invention contains a main agent and a curing agent, the main agent contains a polyester urethane polyol (A) having a structural unit derived from a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups in one molecule, and the curing agent contains a polyisocyanate (B). The reactive adhesive of the present invention has the above structure, the carboxy group concentration in the resin skeleton increases, and the carboxy groups can contact a barrier layer such as an aluminum foil at a high density. Thereby, the adhesion between the adhesive layer and the barrier layer is improved, and excellent retort suitability can be exhibited. Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and embodiments implemented within a range not changing the gist of the present invention are also included.

[0023] <Main Agent> [Polyester Urethane Polyol (A)] The main component of the present invention comprises a polyester urethane polyol (A) having structural units derived from a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule. The polyester urethane polyol (A) can be obtained as a reaction product of a polyester polyol, a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule, and a polyisocyanate. The above polyol may contain polyol components other than the polyester polyol and the above hydroxycarboxylic acid (a1) to the extent that it does not impair the effects of the present invention.

[0024] (Polyester polyol) Polyester polyols constituting polyester urethane polyol (A) include reaction products of polybasic acids and polyhydric alcohols, or ring-opening polymers of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone). Examples of the polybasic acids mentioned above include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid, or their dialkyl esters, and mixtures thereof may also be used. Examples of the above polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, and 1,4-butane. Examples include glycols such as diols, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, and polytetramethylene ether glycol; and polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using, for example, water, ethylene glycol, propylene glycol, trimethylolpropane, and glycerin as initiators; and mixtures thereof may also be used.

[0025] From the viewpoint of adhesive strength, the number average molecular weight of the polyester polyol is preferably 200 or more, more preferably 400 or more, and even more preferably 1,000 or more. It is also preferably 20,000 or less, more preferably 15,000 or less, and even more preferably 10,000 or less. For example, it may be between 200 and 20,000, between 400 and 15,000, or between 1,000 and 10,000. A number average molecular weight in the range of 200 to 20,000 is preferable because it results in an appropriate amount of urethane bonding, leading to excellent toughness and cohesiveness of the cured adhesive. The number-average molecular weights used herein are polystyrene-converted values ​​measured by GPC (gel permeation chromatography).

[0026] The hydroxyl value of the polyester polyol is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less, and even more preferably 35 mgKOH / g or less. It is also preferably 5 mgKOH / g or more, for example, it may be 5 to 50 mgKOH / g, 5 to 40 mgKOH / g, or 5 to 35 mgKOH / g. In this specification, the hydroxyl value can be determined by a method in accordance with JIS K 1557-1.

[0027] (Hydroxycarboxylic acids (a1) having two or more hydroxyl groups and two or more carboxyl groups in one molecule) Examples of hydroxycarboxylic acids (a1) having two or more hydroxyl groups and carboxyl groups in one molecule include compounds having four hydroxyl groups and two carboxyl groups in one molecule, such as saccharic acid; compounds having three hydroxyl groups and two carboxyl groups in one molecule, such as trihydroxyglutaric acid; and compounds having two hydroxyl groups and two carboxyl groups in one molecule, such as dihydroxymalonic acid and tartaric acid. Among these, (a1) is preferable because it has a large proportion of carboxyl group structures in the molecule, which improves adhesion strength to aluminum foil and suppresses delamination after retort sterilization. In this respect, a compound having two hydroxyl groups and two carboxyl groups in one molecule is preferred, and tartaric acid is more preferred.

[0028] It is preferable to react a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and two or more carboxyl groups in one molecule with a polyester polyol to urethaneize a polyisocyanate. When (a1) reacts with the polyisocyanate and is introduced into the polyester urethane polyol (A), carboxyl groups are introduced into the resin backbone as side chains, and it is believed that the adhesion to metal is improved by the carboxyl groups present as side chains. In the above urethane reaction, the amount of (a1) blended is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the mass of the polyester polyol. It is also preferably 5.0% by mass or less, more preferably 3.0% by mass or less. That is, the polyester urethane polyol (A) has a compositional unit mass derived from hydroxycarboxylic acid (a1) that is preferably 0.05% by mass or more, more preferably 1.0% by mass or more, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and may be 0.05 to 5.0% by mass, or 0.1 to 3.0% by mass. A compositional unit proportion derived from (a1) of 0.05% by mass or more improves metal adhesion, and a proportion of 5.0% by mass or less is preferable because it suppresses the generation of fine particles, which are self-reacting products of (a1), resulting in a superior appearance.

[0029] (Polyisocyanate) Examples of polyisocyanates that constitute polyester urethane polyol (A) 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. From the viewpoint of achieving both heat resistance and hygiene, isophorone diisocyanate is preferred.

[0030] (Hydroxycarboxylic acids (C1) having one hydroxyl group and two or more carboxyl groups in one molecule, and carboxylic acid anhydrides (C2) having one or more carboxyl groups in one molecule) From the viewpoint of improving acid resistance, the polyester urethane polyol (A) preferably has a constituent unit at its molecular end that is derived from at least one selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxyl groups in one molecule. By having a constituent unit derived from (c1) or (c2) at the molecular ends of the polyester urethane polyol (A), a carboxyl group is introduced at the molecular ends. The carboxyl group introduced at the molecular ends then interacts with the metal surface through polar attraction and coats the metal surface. As a result, the reaction of acidic components derived from the permeated contents with the metal surface is suppressed, preventing a decrease in adhesion and resulting in excellent acid resistance. A polyester urethane polyol (A) having a structural unit derived from (c1) or (c2) at its molecular terminus can be obtained as a reaction product of a polyester polyol, (a1) above, a polyisocyanate, and a compound selected from the group consisting of (c1) and (c2) above.

[0031] Examples of (c1) include malic acid and citric acid. (c1) is preferably added when a polyol containing the polyester polyol and a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule is reacted with a polyisocyanate in a urethane reaction. Since (c1) has one hydroxyl group in one molecule, the urethane reaction is stopped by the reaction of the hydroxyl group of (c1) with the isocyanate group of the polyisocyanate, and a constituent unit derived from (c1) can be introduced to the molecular terminus of the polyester urethane polyol (A).

[0032] Examples of (c2) include trimellitic anhydride. It is preferable to add (c2) when urethane-forming a polyol containing the polyester polyol and a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule with a polyisocyanate. This causes a ring-opening reaction between the terminal hydroxyl groups of the polyester urethane polyol and the acid anhydride groups of (c2), and allows the introduction of structural units derived from (c2) to the molecular ends of the polyester urethane polyol (A).

[0033] In the above urethane reaction, the blending amounts of (c1) and (c2) are preferably 0.1% by mass or more, more preferably 0.3% by mass or more, based on the mass of the polyester polyol. Also preferably 3.0% by mass or less, more preferably 2.0% by mass or less. That is, the proportion of constituent units derived from at least one selected from the group consisting of (c1) and (c2) in the polyester urethane polyol (A) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and may be 0.1 to 3.0% by mass, 0.1 to 2.0% by mass, or 0.3 to 2.0% by mass. When the proportion of constituent units derived from at least one selected from the group consisting of (c1) and (c2) is 0.1% by mass or more, delamination of the edges of the pouch after hot water treatment is suppressed. If the amount is 3.0% by mass or less, there will be no shortage of hydroxyl groups at the molecular ends of the polyester urethane polyol (A), and sufficient crosslinking will be formed in the reaction with the curing agent containing polyisocyanate described later, thus maintaining heat resistance.

[0034] Polyester polyurethane polyol (A) can be obtained, for example, by compounding and reacting a polyester polyol with a number average molecular weight of 200 to 20,000, a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and two or more carboxyl groups per molecule, and a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups per molecule, such that the ratio of the total number of hydroxyl groups to the number of isocyanate groups in the polyisocyanate (NCO / OH ratio) is less than 1, preferably 0.3 to 0.98. In particular, polyester polyurethane polyol (A) obtained by reacting under conditions where the NCO / OH ratio is less than 1 is preferred because it has high cohesive strength and excellent adhesion to metals.

[0035] From the viewpoint of achieving both adhesive strength and coating suitability, the number average molecular weight of the polyester urethane polyol is preferably 2,000 or more, more preferably 5,000 or more. Furthermore, it is preferably 40,000 or less, more preferably 20,000 or less, and even more preferably 15,000 or less. For example, it may be between 2,000 and 40,000, between 5,000 and 20,000, or between 5,000 and 15,000. Within the above range, it has an appropriate viscosity, excellent coating properties, and excellent adhesive strength after curing. From the viewpoint of resistance to contents and heat resistance, the acid value of the polyester urethane polyol is preferably 3 to 30 mg KOH / g, more preferably 3 to 20 mg KOH / g, and even more preferably 3 to 10 mg KOH / g. When the acid value is within the above range, it is possible to maintain excellent adhesive strength even when stored for a long period of time after filling with acidic contents. Furthermore, since there is no shortage of hydroxyl groups in the polyester urethane polyol, the crosslinking density of the cured adhesive becomes sufficient, and excellent heat resistance can be maintained.

[0036] The hydroxyl value of the polyester urethane polyol is preferably 30 mg KOH / g or less, more preferably 25 mg KOH / g or less, and even more preferably 15 mg KOH / g or less. It is also preferably 1 mg KOH / g or more, for example, it may be 1 to 30 mg KOH / g, 1 to 25 mg KOH / g, or 1 to 15 mg KOH / g.

[0037] [Other polyols] The main component in the present invention may contain polyol components other than polyester urethane polyol (A), as long as the effects of the present invention are not impaired. Examples of such polyol components include polyester urethane polyols, polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyvalerolactone polyols, polyolefin polyols, polyurethane polyols, acrylic polyols, silicone polyols, polyhydroxyalkanes, and fluorinated polyols, which do not contain (a1). Furthermore, polyols derived from vegetable oils, such as castor oil polyols, may also be included. Using polyols derived from vegetable oils can increase the biomass content of the adhesive and reduce its environmental impact.

[0038] [Particle number concentration measurement] In the aforementioned main component, when measuring the particle number concentration using dynamic light scattering, the number concentration of particles with a particle diameter of 25 μm or more, based on the solid content mass, is preferably 4000 particles / mL or less, and more preferably 2000 particles / mL or less. Being within this range helps to suppress the formation of air bubble nuclei and the resulting appearance defects when the material is packaged. The number concentration of particles with a particle diameter of 25 μm or more, based on the solid content mass, can be calculated by the following method. <Method for measuring the number concentration of particles with a particle diameter of 25 μm or more> Using an automated dynamic light scattering particle measurement system, the particle size and particle number concentration (particles / mL) of insoluble particles in the diluted main solution are measured. Then, from the resulting histogram (vertical axis: particle number concentration (particles / mL), horizontal axis: particle size), the particle number concentration (particles / mL) of particles with a particle size of 25 μm or larger is calculated. The measurement is performed three times, and using the obtained values, the particle number concentration of particles with a particle size of 25 μm or larger, based on the solid content mass, is calculated based on the following formula. Formula) Particle number concentration = [{Σ(a1+a2+a3) / 3×n]-{b×(n-1)}]×(X / 100)-c×(100-X / 100) [In the above formula, X: Solid content concentration (mass%) of the main component before dilution a1: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the first measurement. a2: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the second measurement. a3: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the third measurement. b: Number concentration of particles with a particle size of 25 μm or larger in the dilution solvent (particles / mL) c: Number concentration of particles with a particle size of 25 μm or larger in the added solvent during synthesis (particles / mL) n: Dilution ratio (times)

[0039] As an automated measurement system for dynamic light scattering particles, the "SLS-2000" (manufactured by Particle Measurement Systems, equipped with the LiQuiazIIE20P sensor) can be used. Measurement conditions may include a measurement atmosphere of 25°C and a flow rate of 20 mL / min. The measured values ​​are output as a histogram with particle number concentration (particles / mL) on the vertical axis and particle diameter of a constant width on the horizontal axis. From this histogram, the particle number concentration (particles / mL) of particles with a diameter of 25 μm or larger can be calculated.

[0040] <Hardening agent> The curing agent in the present invention comprises a polyisocyanate (B). Examples of polyisocyanate (B) include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, trifunctional or more polyisocyanate monomers, dimers, trimers, biuretes or allophanates derived from the above diisocyanates or trifunctional or more polyisocyanate monomers, and polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and the above diisocyanates or trifunctional or more polyisocyanate monomers. Among these, aliphatic diisocyanates, alicyclic diisocyanates, aromatic aliphatic diisocyanates, and their derivatives are preferred from the viewpoint of hygiene.

[0041] Examples of aliphatic diisocyanates include 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-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate.

[0042] Examples of alicyclic diisocyanates include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 4,4′-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanate methyl)cyclohexane, and 1,3-bis(isocyanate methyl)cyclohexane.

[0043] Examples of aromatic diisocyanates include m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4′-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 4,4′-diphenylmethanediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, a mixture of 2,4-tolylenediisocyanate and 2,6-tolylenediisocyanate, 4,4′-toluidinediisocyanate, dianisidinediisocyanate, and 4,4′-diphenyletherdiisocyanate.

[0044] Examples of aromatic aliphatic diisocyanates include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, a mixture of 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate, ω,ω′-diisocyanate-1,4-diethylbenzene, 1,3-bis(1-isocyanate-1-methylethyl)benzene, 1,4-bis(1-isocyanate-1-methylethyl)benzene, and a mixture of 1,3-bis(1-isocyanate-1-methylethyl)benzene and 1,4-bis(1-isocyanate-1-methylethyl)benzene.

[0045] Examples of polyisocyanate monomers with three or more functions include organic triisocyanates such as triphenylmethane-4,4′,4″-triisocyanate, 1,3,5-triisocyanatebenzene, and 2,4,6-triisocyanatetoluene; and organic tetraisocyanates such as 4,4′-diphenyldimethylmethane-2,2′-5,5′-tetraisocyanate.

[0046] Polyisocyanate (B) may be a polyisocyanate having a urethane bond, obtained by adding a polyol to the polyisocyanate described above. Examples of the polyols include low molecular weight polyols with 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 polyester polyols, polyether ester polyols, polyesteramide polyols, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxyalkanes, castor oil, and polyurethane polyols with a molecular weight of 200 to 20,000.

[0047] Polyisocyanate (B) may be used alone or in combination of two or more types. In particular, from the viewpoint of hygiene, flexibility and heat resistance, it is preferably an alicyclic diisocyanate, an aliphatic diisocyanate, or a derivative thereof, more preferably it includes at least one selected from the group consisting of adducts of isophorone diisocyanate and adducts of xylylene diisocyanate, even more preferably it includes at least one selected from the group consisting of reaction products of isophorone diisocyanate and trimethylolpropane and reaction products of xylylene diisocyanate and trimethylolpropane, and especially preferably it includes reaction products of isophorone diisocyanate and trimethylolpropane and reaction products of xylylene diisocyanate and trimethylolpropane.

[0048] Polyisocyanate (B) preferably contains 10 to 90% by mass of the reaction product of isophorone diisocyanate and trimethylolpropane, and 10 to 90% by mass of the reaction product of xylylene diisocyanate and trimethylolpropane, based on the solid content mass of polyisocyanate (B), and more preferably contains 40 to 80% by mass of the reaction product of isophorone diisocyanate and trimethylolpropane, and 20 to 60% by mass of the reaction product of xylylene diisocyanate and trimethylolpropane.

[0049] <Other ingredients> The reactive adhesive of the present invention may further contain a silane coupling agent to enhance its resistance to hot water. Examples of silane coupling agents include those having functional groups such as vinyl groups, epoxy groups, amino groups, imino groups, and mercapto groups, and functional groups such as methoxy groups and ethoxy groups. More specifically, examples include trialksylsilanes having vinyl groups such as vinyltrimethoxysilane and vinyltriethoxysilane; trialksylsilanes having amino groups such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; and trialksylsilanes having glycidyl groups such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. From the viewpoint of hygiene and resistance to hot water, the amount of silane coupling agent is preferably 0.1% by mass or less based on the solid content of the adhesive.

[0050] The reactive adhesive of the present invention may further contain additives as needed, such as antioxidants, ultraviolet absorbers, hydrolysis inhibitors, fungicides, thickeners, plasticizers, pigments, and fillers. It may also contain known catalysts, additives, etc., to adjust the curing reaction.

[0051] <Organic solvents> The reactive adhesive of the present invention can be used in either solvent-based or solvent-free form, and may contain a solvent as needed. If the viscosity of the reactive adhesive is 100 to 10,000 mPa·s, preferably 100 to 5,000 mPa·s, at room temperature to 150°C, preferably at room temperature to 100°C, it may be used in solvent-free form. If the viscosity of the adhesive is higher than the above range, it may be diluted with a solvent and used as a solvent-based adhesive. Suitable organic solvents include those that are inert to isocyanates, such as ester-based solvents like ethyl acetate; ketone-based solvents like methyl ethyl kent; and aromatic hydrocarbon-based solvents like toluene and xylene.

[0052] <Preparation of reactive adhesives> The reactive adhesive of the present invention can be manufactured by mixing a main component containing polyester urethane polyol (A) and a curing agent containing polyisocyanate (B) in an appropriate mixing ratio. When mixing the main component and the curing agent, the ratio of the number of isocyanate groups in the curing agent to the number of hydroxyl groups in the main component (NCO / OH) is preferably in the range of 1.0 to 5.0. Within this range, sufficient crosslinking density is achieved, resulting in excellent adhesive strength. This is also preferable from the viewpoint of curing time, hygiene, and cost-effectiveness.

[0053] The adhesive of the present invention can be used by applying it to the film surface using a solvent-type or solvent-free laminator, allowing the solvent to evaporate in the case of the solvent-type, or by bonding the surfaces together as is in the case of the solvent-free type, and then curing it at room temperature or under heating. Generally, it is advantageous to use the solvent-free type with an application amount in the range of 1.0 to 2.0 g / m2 of dry solids, and the solvent-type with an application amount in the range of 2.0 to 5.0 g / m2 of dry solids.

[0054] <Laminates, packaging> The laminate of the present invention has an adhesive layer formed from the reactive adhesive between a first substrate and a second substrate. That is, the laminate of the present invention sequentially comprises at least a first substrate layer, an adhesive layer which is a cured product of the reactive adhesive, and a second substrate layer. For example, the reactive adhesive can be applied to one side of the first substrate using a dry laminator, the second substrate can be bonded to it, and the adhesive layer located between the two substrates can be formed by curing it at room temperature or under heating. The laminate of the present invention may further have another substrate arranged via an adhesive layer or the like, for example, a configuration such as "first substrate layer / adhesive layer / second substrate layer / adhesive layer / third substrate layer" or "first substrate layer / adhesive layer / second substrate layer / adhesive layer / third substrate layer / adhesive layer / fourth substrate layer". Furthermore, the packaging of the present invention is made using these laminates. If the reactive adhesive contains an organic solvent, a drying step may be provided as appropriate. The thickness of the laminate may be 10 μm or more, and the amount of adhesive applied after drying is 1 to 10 g / m². 2 That's fine.

[0055] [Base material] The base material is not particularly limited and can include plastic films, paper, gas barrier materials, sealants, etc., commonly used for packaging applications. The first base material and the second base material may be of the same type or different types. As the plastic film, a thermoplastic resin or a thermosetting resin film can be used, with a thermoplastic resin film being preferred. Examples of thermoplastic resins include polyolefins, polyesters, polyamides, polystyrenes, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, and cellulose-based plastics. The thickness of the plastic film may be 5 to 50 μm or 10 to 30 μm.

[0056] Examples of paper include natural paper and synthetic paper. Examples of gas barrier substrates include metal foils such as aluminum foil, and plastic films having a vapor-deposited layer of aluminum, silica, alumina, etc. For example, in the case of aluminum foil, a thickness in the range of 3 to 50 μm is preferred from an economic standpoint.

[0057] The sealant has heat-sealing properties and examples include polyethylene 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 resins are preferred from the viewpoint of heat resistance during retorting, and unstretched polypropylene is particularly preferred from the viewpoint of heat-sealing properties. The thickness of the sealant may be 10-60 μm or 15-40 μm. Furthermore, the sealant may be given uneven surfaces with height differences of 5-20 μm to provide slipperiness and tear resistance to the packaging. In addition to aluminum foil, the sealant may also have a vapor-deposited layer of aluminum, silica, alumina, etc.

[0058] The substrate may have a printed layer on it. The printed layer is a layer that forms any desired printed pattern such as letters, numbers, pictures, figures, symbols, patterns, etc., for decoration, display of contents, display of expiration date, display of manufacturer, seller, etc., and for display or aesthetic purposes, and also includes a solid print layer. The printed layer can be formed using conventionally known pigments and dyes, and the method of forming the printed layer The method is not particularly limited. The thickness of the printed layer may be 0.1 to 10 μm, 1 to 5 μm, or 1 to 3 μm. [Examples]

[0059] The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to the following examples unless it exceeds the gist of the invention. Unless otherwise specified, "parts" and "%" refer to "parts by mass" and "mass%" respectively. Blank spaces in the table indicate that the ingredient is not included.

[0060] <Number average molecular weight (Mn)> The average molecular weight of standard polyethylene was measured using an HLC-8420GPC EcoSEC Elite (Tosoh Corporation) column, TSKgel Super HM-M and TSKgel Super HM-L (Tosoh Corporation) with a column temperature of 40°C, THF as the eluent, a flow rate of 0.1 ml / min, RI detection, and a sample concentration of 1.0 mg / mL. The value was calculated using the ethylene equivalent.

[0061] <Measurement of Acid Value (AV)> Approximately 1 g of the sample was accurately weighed into a stoppered Erlenmeyer flask and dissolved in 100 ml of methyl ethyl ketone. Phenolphthalein reagent was added as an indicator and held for 30 seconds. The solution was then titrated with 0.1 N alcoholic potassium hydroxide solution until it turned pale pink, and the acid value (mgKOH / g) was determined using the following formula. Acid value (mgKOH / g)=(5.611×a×F) / S However, S: Sample volume (g) a: Amount of 0.1N alcoholic potassium hydroxide solution consumed (ml) F: Titer of 0.1N alcoholic potassium hydroxide solution

[0062] <Hydroxyl Value (OHV)> Approximately 1 g of the sample was accurately weighed into a stoppered Erlenmeyer flask, and 5 ml of the acetylating agent (a solution of 20 g of acetic anhydride dissolved in pyridine, with a volume of 100 ml) was added. The mixture was heated and stirred at 110°C for approximately 2 hours. After that, the stoppered Erlenmeyer flask was cooled with water, 1.2 ml of distilled water was added, and the mixture was heated for a further 5 minutes. Phenolphthalein reagent was added as an indicator and held for 30 seconds. The solution was then titrated with 0.1 N alcoholic potassium hydroxide solution until it turned pale pink, and the hydroxyl value (mg KOH / g) was determined using the following formula. Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.05} / S] + D However, S: Sample volume (g) a: Amount of 0.1N alcoholic potassium hydroxide solution consumed (ml) b: Amount of 0.1N alcoholic potassium hydroxide solution consumed in the blank experiment (ml) F: Titer of 0.1N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

[0063] <Synthesis of polyester polyols> (Polyester polyol (pes-1)) 30 parts sebacic acid, 70 parts isophthalic acid, 20 parts ethylene glycol, 50 parts neopentyl glycol, and 50 parts 1,6-hexanediol were charged, and the esterification reaction was carried out at 200-230°C for 8 hours. After distilling off the predetermined amount of water, the pressure was gradually reduced to 1.21 × 10⁻⁶ 2 ~1 × 10 3 The esterification reaction was carried out at Pa, 230-250°C for 5 hours to obtain polyester polyol (pes-1).

[0064] (Polyester polyol (pes-2 to pes-4)) Polyester polyols (pes-2) to (pes-4) were obtained in the same manner as polyester polyol (pes-1), except that the composition of the raw materials was changed as shown in Table 1.

[0065] [Table 1]

[0066] <Synthesis of polyester urethane polyol> (Polyester urethane polyol A1) To 100 parts of polyester polyol (pes-1), 0.5 parts of trihydroxyglutaric acid, 0.7 parts of trimellitic anhydride (TMA), and 3.0 parts of isophorone diisocyanate (IPDI) were charged, and the urethane reaction was carried out at 150°C for 3 hours. 90 parts of ethyl acetate were added, and the mixture was stirred at 50°C for 1 hour. The mixture was then filtered through a 200-mesh polyethylene filter to obtain polyester urethane polyol A1 solution.

[0067] (Polyester urethane polyol A2~A11, A13~A23) Polyester urethane polyols A2-A11 and A13-A23 solutions were obtained in the same manner as for polyester urethane polyol A1, except that the composition of the raw materials was changed as shown in Table 2.

[0068] (Polyester urethane polyol A12) To 100 parts of polyester polyol (pes-1), 0.5 parts of trihydroxyglutaric acid, 0.7 parts of trimellitic anhydride (TMA), 2.3 parts of tolylene diisocyanate (TDI), and 30 parts of ethyl acetate were charged, and the urethane reaction was carried out at 90°C for 3 hours. 40 parts of ethyl acetate were added, and the mixture was stirred at 50°C for 1 hour. The mixture was then filtered through a 200-mesh polyethylene filter to obtain polyester urethane polyol A12 solution.

[0069] [Table 2]

[0070] The abbreviations used in Table 2 are explained below. IPDI: Isophorone diisocyanate TDI: Tolylene diisocyanate

[0071] <Preparation of polyisocyanates> (Polyisocyanate B1) Polyisocyanate B1 solution was obtained by mixing 35 parts of TMP adduct of IPDI, 35 parts of TMP adduct of XDI, and 30 parts of ethyl acetate at 40°C under a nitrogen atmosphere for 30 minutes.

[0072] (Polyisocyanates B2-B5) Polyisocyanate solutions B2 to B5 were obtained in the same manner as for polyisocyanate B1, except that the raw materials were changed to those listed in Table 3.

[0073] [Table 3]

[0074] <Manufacturing of reactive adhesives> [Examples 1-23, Comparative Examples 1-7] Adhesives were obtained by compounding the main component, curing agent, and organic solvent according to the formulations shown in Tables 4 and 5. For main components without additives, a polyester urethane polyol solution was used as the main component. For main components containing additives, a polyester urethane polyol solution with the additives added was used as the main component.

[0075] <Measurement of particle number concentration of the main ingredient> The main component obtained above was diluted with ethyl acetate and adjusted to a viscosity of approximately 50 mPa·s or less at 25°C. The particle size and particle number concentration (particles / mL) of insoluble particles contained in the diluted main component solution were measured using the SLS-2000 dynamic light scattering particle automated measurement system (Particle Measurement Systems, equipped with LiQuiazIIE20P sensor). The measurement conditions were a measurement atmosphere of 25°C and a flow rate of 20 mL / min. The measured values ​​were output as a histogram with particle number concentration (particles / mL) on the vertical axis and particle size of a constant width on the horizontal axis. Three measurements were performed for each sample, and the particle number concentration of particles 25 μm or larger was calculated as described below. The particle number concentration (particles / mL) of particles 25 μm or larger in the dilution solvent and the solvent added during synthesis was calculated in the same manner as above. Particle number concentration = [{Σ(a1+a2+a3) / 3×n]-{b×(n-1)}]×(X / 100)-c×(100-X / 100) However, X: Solid content concentration (mass%) of the main component before dilution. a1: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the first measurement. a2: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the second measurement. a3: Number concentration of particles with a particle size of 25 μm or larger (particles / mL) in the third measurement. b: Number concentration of particles with a particle size of 25 μm or larger in the dilution solvent (particles / mL) c: Number concentration of particles with a particle size of 25 μm or larger in the added solvent during synthesis (particles / mL) n: Dilution ratio (times)

[0076] <Evaluation of reactive adhesives> (Fabrication of a 4-layer laminate) A laminate consisting of four layers—polyethylene terephthalate (PET) film (E5102, manufactured by Toyobo Co., Ltd., 12 μm thick), aluminum (AL) foil (manufactured by Toyo Aluminum, 9 μm thick), nylon (NY) film (ON-RTBC, manufactured by Unitika, double-sided corona treated, 15 μm thick), and unoriented polypropylene (CPP) film (ZK-207, manufactured by Toray Industries, 70 μm thick, surface corona discharge treated)—was prepared using the method described below. First, the reactive adhesives obtained in the examples and comparative examples were applied to polyethylene terephthalate film using a laminator at room temperature. After the solvent evaporated, the applied surface was laminated to aluminum foil. Next, the reactive adhesive was applied to the other side of the aluminum foil in the same manner, and after the solvent evaporated, the applied surface was laminated to nylon film. Then, the reactive adhesive was applied to the other side of the nylon film in the same manner, and after the solvent evaporated, the applied surface was laminated to unstretched polypropylene film. The laminates were then incubated at 40°C for 4 days to produce a laminate. The amount of adhesive applied after drying of each adhesive layer was 4.5 g / m². 2 That's what I decided.

[0077] (Acid resistance test) Using the obtained laminate, a pouch measuring 9 cm × 12 cm was prepared, and a mixture of 6.7 parts each of vinegar, ketchup, and salad oil with a concentration of 4.2% or higher was vacuum-filled as the contents. After sterilizing the pouch with hot water at 10 rpm, 135°C, 30 minutes, and under pressure of 0.3 MPa, the contents were discarded, the pouch was thoroughly washed, and air-dried. The following day, a test specimen measuring 15 mm × 300 mm was prepared, and the laminate strength (N / 15 mm) between the NY film and AL foil was measured using a tensile testing machine at a temperature of 20°C and relative humidity of 65% by T-peel at a peeling speed of 30 cm / min, and evaluated according to the following criteria. A :5.5N / 15mm or more B: 5.0N / 15mm or more, less than 5.5N / 15mm C: 4.5N / 15mm or more, less than 5.0N / 15mm D: 4.5N / less than 15mm

[0078] (Extreme retort testing of flexible film (Erichsen retort evaluation)) From the resulting laminate, a 6cm x 11cm film was cut out, and an 8mm deep hemispherical depression was formed in the center using an Erichsen tester. The film with the depression was then cut in half with a cutter to obtain a 3cm x 11cm film. Next, the 3cm x 11cm film was placed in a retort pouch filled with water, vacuum-sealed, and then sterilized with hot water at 10 rpm, 130°C, for 30 minutes under a pressure of 3 MPa. After hot water sterilization, the state of delamination in the depression area of ​​the film was visually observed and evaluated according to the following criteria. A: No delamination B: Delamination in the recessed area exceeds 0 area % and is 5 area % or less, and there is no delamination outside the recessed area. C: Delamination in the recessed area exceeds 5% but is 40% or less, and there is no delamination outside the recessed area. D: Delamination of recessed areas exceeds 40% and is 80% or less. E: Delamination of the recessed area exceeds 80% of the area. Or, If delamination in the recessed area exceeds 40% but is 80% or less, and delamination is present in areas other than the recessed area (unusable).

[0079] (Appearance evaluation) From the resulting laminate, a 10cm x 10cm film was cut out, the number of air bubbles was visually counted, and it was evaluated according to the following criteria. A: Number of bubbles: 0-1 B: Number of bubbles: 2-3 C: Number of bubbles is 3 or more

[0080] (Extraction evaluation) PET film (Toyobo Co., Ltd. E5102, 12 μm thick) and LLDPE (Mitsui Chemicals Tohcello Co., Ltd. TUX-FCD, 50 μm thick) are bonded together with a reactive adhesive (application amount 3.5 g / m²). 2The layers were bonded together using ( ) and aged at 40°C for 96 hours. The resulting laminate was placed in a migration cell (FABES Forchungs-Gmbh) and 25 ml of isooctane was added to the top of the migration cell as a food imitation solution. After heating in an oven at 100°C for 1 hour, it was stored at 60°C for 10 days. 25 ml of isooctane was removed. The solution was then concentrated to 1 mL, and the amount of silane coupling agent was quantified by GC-MS. Based on the extracted volume... Therefore, the evaluation was conducted according to the following criteria. A: 0.15μg / kg or less B: Greater than 0.15 μg / kg and less than or equal to 2.00 μg / kg C: Exceeds 2.00 μg / kg

[0081] [Table 4]

[0082] [Table 5]

[0083] According to the results in Tables 4 and 5, the reactive adhesive of the present invention exhibited excellent adhesion and showed good results in the Erichsen retort evaluation. In particular, when the amount of hydroxycarboxylic acid (a1) blended was 0.1 to 3.0% by mass based on the mass of the polyester polyol, the Erichsen retort evaluation improved, acid resistance (laminate strength of AL / NY after retorting) improved, and fine particles in the main component were suppressed, resulting in excellent appearance of the laminate film. Furthermore, by introducing constituent units derived from hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups per molecule, or carboxylic acid anhydride (c2) having one or more carboxyl groups per molecule, the Erichsen retort resistance was further improved, and when the total amount of (c1) and (c2) blended was 0.1 to 2.0% by mass based on the mass of the polyester polyol, excellent balance between Erichsen retort evaluation and acid resistance was achieved. Furthermore, the curing agent (B), containing reaction products of isophorone diisocyanate and trimethylolpropane, and reaction products of xylylene diisocyanate and trimethylolpropane, demonstrated excellent balance between appearance, acid resistance, and Erichsen retort evaluation. The silane coupling agent content was 0.1% by mass or less based on the mass of polyester urethane polyol (A), which allowed for a reduction in the amount of silane coupling agent extracted and a balance between Erichsen retort evaluation and acid resistance (laminated strength of AL / NY after retorting).

Claims

1. A reactive adhesive comprising a main component and a curing agent, The main component comprises a polyester urethane polyol (A) having structural units derived from a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule, A reactive adhesive in which the curing agent contains polyisocyanate (B).

2. The reactive adhesive according to claim 1, wherein the hydroxycarboxylic acid (a1) is a compound having two hydroxyl groups and two carboxyl groups in one molecule.

3. The reactive adhesive according to claim 1, wherein the hydroxycarboxylic acid (a1) is tartaric acid.

4. The reactive adhesive according to claim 1, wherein the polyester urethane polyol (A) is a reaction product of a polyester polyol, a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and carboxyl groups in one molecule, and a polyisocyanate, and the amount of the hydroxycarboxylic acid (a1) is 0.1 to 3.0% by mass based on the mass of the polyester polyol.

5. The reactive adhesive according to claim 1, wherein the polyester urethane polyol (A) has constituent units at its molecular termini that are derived from at least one selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxyl groups in one molecule.

6. The reactive adhesive according to claim 1, wherein the polyester urethane polyol (A) is a reaction product of a polyester polyol, a hydroxycarboxylic acid (a1) having two or more hydroxyl groups and two or more carboxyl groups in one molecule, a polyisocyanate, and a compound selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxyl group and two or more carboxyl groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxyl groups in one molecule, and the total amount of (c1) and (c2) blended is 0.1 to 2.0% by mass based on the mass of the polyester polyol.

7. The reactive adhesive according to claim 1, wherein the polyisocyanate (B) comprises at least one selected from the group consisting of reaction products of isophorone diisocyanate and trimethylolpropane, and reaction products of xylylene diisocyanate and trimethylolpropane.

8. The reactive adhesive according to claim 1, wherein the polyisocyanate (B) comprises a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane.

9. The reactive adhesive according to claim 1, wherein the main component has a number concentration of particles with a particle diameter of 25 μm or more, based on the solid content mass, which is calculated based on particle number concentration measurement using the dynamic light scattering method shown below, and the number concentration of such particles is 4000 particles / mL or less. <Method for measuring the number concentration of particles with a particle diameter of 25 μm or more> Using an automated dynamic light scattering particle measurement system, the particle size and particle number concentration (particles / mL) of insoluble particles in the diluted main solution are measured. Then, from the resulting histogram (vertical axis: particle number concentration (particles / mL), horizontal axis: particle size), the particle number concentration (particles / mL) of particles with a particle size of 25 μm or larger is calculated. The measurement is performed three times, and using the obtained values, the particle number concentration of particles with a particle size of 25 μm or larger, based on the solid content mass, is calculated according to the following formula. Formula) Particle number concentration = [{Σ(a1+a2+a3) / 3×n]-{b×(n-1)}]×(X / 100)-c×(100-X / 100) [In the above formula, X: Solid content concentration (mass%) of the main component before dilution a1: Number concentration of particles with a particle diameter of 25 μm or larger (particles / mL) in the first measurement. a2: Number concentration of particles with a particle diameter of 25 μm or larger (particles / mL) in the second measurement. a3: Number concentration of particles with a particle diameter of 25 μm or larger (particles / mL) in the third measurement. b: Number concentration of particles with a particle size of 25 μm or larger in the dilution solvent (particles / mL) c: Number concentration of particles with a particle size of 25 μm or larger in the solvent added during synthesis (particles / mL) n: Dilution ratio (times) [is]

10. The reactive adhesive according to claim 1, wherein the content of the silane coupling agent contained in the reactive adhesive is 0.1% by mass or less based on the mass of polyester urethane polyol (A).

11. A laminate having an adhesive layer formed from the reactive adhesive described in claims 1 to 10 between a first substrate and a second substrate.

12. A packaging body made using the laminate described in claim 11.

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