Reactive adhesives, laminates and packaging

Abstract

To provide a reactive adhesive capable of forming a package that does not cause delamination even when it is filled with highly acidic or oily foods as contents and retorted at a high temperature, and to provide a laminate and a package made using the adhesive. [Solution] The above-mentioned problems are solved by a reactive adhesive comprising a base agent and a curing agent, wherein the base agent comprises a polyesterurethane polyol (A) having structural units 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 comprises a polyisocyanate (B).

Description

[Technical Field]

[0001] The present invention relates to an adhesive having excellent adhesive properties that is suitable for use in laminating a plurality of various plastic films, metallized films, or metal foils to produce a packaging laminate for food, medical products, cosmetics, etc. The present invention also relates to a packaging laminate used for packaging food, medical products, cosmetics, etc. [Background technology]

[0002] In recent years, composites formed by laminating 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, etc. Composite films formed by laminating these plastic films with metal foils or metal-deposited films are often used in fields that require resistance to harsh conditions, such as packaging bags for heavy items such as bottled or tubed products, and packaging bags for hot water boiling and retort treatments for cooking and sterilization. They require sufficient adhesion between the films (lamination strength), sufficient strength in the bag area (seal strength), and water and oil resistance at high temperatures (suitability for boiling and retort). In particular, there is a growing demand for packaging bags in which composite films are tightly fitted to the shape of food in order to save space and maintain hygiene. Accordingly, composite films are required to be flexible and to be able to withstand boiling and retorting in environments where they are bent and distorted.

[0003] In response to these demands, studies have been conducted to improve the adhesive strength and heat resistance to metal foil or metal-deposited film by adding an epoxy-based silane coupling agent to a laminating adhesive. However, in recent years, restrictions on the amount of epoxy-based silane coupling agents that can be transferred to food have been tightened, particularly in Europe. Therefore, there is a demand for reactive adhesives that reduce or eliminate the coupling agent and improve adhesion to metals by other means.

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

[0005] Patent Document 2 describes that in an adhesive composition for dry lamination containing a polyol component and a polyisocyanate component, the adhesive composition contains, as part of the polyol component, 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, in an amount such that the acid value derived from the hydroxycarboxylic acid accounts for 1 to 20 of the acid value of the solid content of the adhesive composition, thereby improving adhesion to metal foil films and vapor-deposited films. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-132902 [Patent Document 2] Japanese Patent Application Publication No. 08-183943 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the adhesive described in Patent Document 1 exhibits good adhesion during boiling or retorting at a moderate temperature (up to 120°C), it may not adhere well enough to some contents or substrates during retorting at a high temperature (120°C to 135°C), resulting in peeling. For example, packaging bags made using a common composite film in which polyester or nylon film / aluminum foil / unstretched polypropylene film are laminated together suffer from the problem of delamination (peeling) at the heat-sealed portion immediately after retorting and after aging. Furthermore, the adhesive described in Patent Document 2 has the same problem as Patent Document 1 in that delamination occurs at the heat-sealed portion when retorted in a high-temperature range.

[0008] The present invention has been made in view of the above background, and aims to provide a reactive adhesive that can form a package that does not delaminate even when filled with highly acidic or oily foods and retorted at high temperatures, as well as a laminate and package made using the adhesive. [Means for solving the problem]

[0009] <1> The present invention relates to a reactive adhesive comprising a base agent and a curing agent, wherein the base agent comprises a polyesterurethane polyol (A) having structural units derived from a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule, and the curing agent comprises a polyisocyanate (B).

[0010] <2> The present invention relates to a compound in which the hydroxycarboxylic acid (a1) is a compound having two hydroxy groups and two carboxy groups in one molecule. <1> The reactive adhesive described herein is

[0011] <3> The present invention relates to a method for producing a hydroxycarboxylic acid (a1) comprising the steps of: <1> or <2> The reactive adhesive described herein is

[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 hydroxy groups and two or more carboxy groups in one molecule, and a polyisocyanate, and the amount of the hydroxycarboxylic acid (a1) is 0.1 to 3.0 mass% based on the mass of the polyester polyol. <1> ~ <3> The reactive adhesive according to any one of claims 1 to 4.

[0013] <5> The present invention provides a polyester urethane polyol (A) having, at its molecular terminal, a structural unit derived from at least one selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxy group and two or more carboxy groups in one molecule, and a carboxylic acid anhydride (c2) having one or more carboxy groups in one molecule. <1> ~ <4> The reactive adhesive according to any one of claims 1 to 4.

[0014] <6> The present invention provides a polyester urethane polyol (A) which is a reaction product of a polyester polyol, a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups in one molecule, a polyisocyanate, and a compound selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxy group and two or more carboxy groups in one molecule and a carboxylic acid anhydride (c2) having one or more carboxy groups in one molecule, and the total amount of (c1) and (c2) is 0.1 to 2.0 mass% based on the mass of the polyester polyol. <1> ~ <5> The reactive adhesive according to any one of claims 1 to 4.

[0015] <7> The present invention relates to a polyisocyanate (B) comprising at least one selected from the group consisting of a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane. <1> ~ <6> The reactive adhesive according to any one of claims 1 to 4.

[0016] <8> The present invention relates to a polyisocyanate (B), wherein the polyisocyanate (B) includes a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane. <1> ~ <7> The reactive adhesive according to any one of claims 1 to 4.

[0017] <9> In the present invention, the base agent has a number concentration of particles having 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, of 4000 particles / mL or less. <1> ~ <8> The reactive adhesive according to any one of claims 1 to 4. <Method for measuring the number concentration of particles with a particle diameter of 25 μm or more> Using an automatic dynamic light scattering particle measurement system, the particle size and particle number concentration (particles / mL) of insoluble particles in the diluted base solution are measured. Next, the particle number concentration (particles / mL) of particles with a particle size of 25 μm or more is calculated from the resulting histogram (vertical axis: particle number concentration (particles / mL), horizontal axis: particle size). Measurements are performed three times, and the number concentration of particles with a particle size of 25 μm or more is calculated based on the solid mass using 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 base agent before dilution (mass%) a1: Number concentration of particles with a particle diameter of 25 μm or more in the first measurement (particles / mL) a2: Number concentration of particles with a particle diameter of 25 μm or more in the second measurement (particles / mL) a3: Number concentration of particles with a particle diameter of 25 μm or more (particles / mL) in the third measurement b: Number concentration of particles with a particle diameter of 25 μm or more in the dilution solvent (particles / mL) c: Number concentration of particles with 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 is directed to a reactive adhesive in which the content of the silane coupling agent is 0.1% by mass or less based on the mass of the polyesterurethane polyol (A). <1> ~ <9> The reactive adhesive according to any one of claims 1 to 4.

[0019] <11> The present invention provides a method for manufacturing a laminated film having a first substrate and a second substrate, <1> ~ <10> The present invention relates to a laminate having an adhesive layer formed from the reactive adhesive according to any one of claims 1 to 4.

[0020] <12> The present invention provides <11> The present invention also relates to a packaging body made using the laminate described above. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a reactive adhesive capable of forming a package that does not delaminate even when highly acidic or oily foods are filled as the contents and retorted at high temperatures, as well as a laminate and package that do not delaminate even when highly acidic or oily foods are filled as the contents and retorted at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0022] <<Reactive adhesive>> The reactive adhesive of the present invention comprises a base agent and a curing agent, wherein the base agent comprises a polyesterurethane polyol (A) having structural units derived from a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule, and the curing agent comprises a polyisocyanate (B). The reactive adhesive of the present invention has the above-described structure, which increases the carboxy group concentration in the resin skeleton and enables the carboxy groups to contact a barrier layer such as an aluminum foil at a high density. This improves adhesion between the adhesive layer and the barrier layer, enabling the adhesive to exhibit excellent retort suitability. The following describes in detail the embodiments of the present invention. The present invention is not limited to the following embodiments, and includes embodiments that are implemented within the scope of the present invention.

[0023] <Main ingredient> [Polyester urethane polyol (A)] The base resin in the present invention contains a polyesterurethane polyol (A) having structural units derived from a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule. The polyesterurethane polyol (A) can be obtained as a reaction product of a polyester polyol, a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule, and a polyisocyanate. The polyol may contain a polyol component other than the polyester polyol and the hydroxycarboxylic acid (a1) as long as the effects of the present invention are not impaired.

[0024] (polyester polyol) Examples of polyester polyols constituting the polyester urethane polyol (A) include reaction products of polybasic acids and polyhydric alcohols, and ring-opening polymers of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone). Examples of the polybasic acid include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid, and dialkyl esters thereof, and mixtures of these may also be used. Examples of the polyhydric alcohol include glycols such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,4-butanediol, 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 an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran using a low-molecular-weight polyol such as water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin as an initiator; and mixtures of these may also be used.

[0025] From the viewpoint of adhesive strength, the polyester polyol has a number average molecular weight of preferably 200 or more, more preferably 400 or more, and even more preferably 1,000 or more. The number average molecular weight is also preferably 20,000 or less, more preferably 15,000 or less, and more preferably 10,000 or less, and may be, for example, 200 to 20,000, 400 to 15,000, or 1,000 to 10,000. A number average molecular weight in the range of 200 to 20,000 is preferred because it results in an appropriate urethane bond amount and results in excellent toughness and cohesive strength of the adhesive cured product. The number average molecular weight in this specification is a value calculated as polystyrene 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, and may be, for example, 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 acid (a1) having two or more hydroxy groups and two or more carboxy groups in one molecule) Examples of hydroxycarboxylic acids (a1) having two or more hydroxy groups and two or more carboxy groups in one molecule include compounds such as saccharinic acid, which has four hydroxy groups and two carboxy groups in one molecule; compounds such as trihydroxyglutaric acid, which has three hydroxy groups and two carboxy groups in one molecule; and compounds such as dihydroxymalonic acid and tartaric acid, which have two hydroxy groups and two carboxy groups in one molecule. Among these, (a1) is preferably a compound having two hydroxy groups and two carboxy groups per molecule, more preferably tartaric acid, from the viewpoints of having a large proportion of carboxy group structures in the molecule, improving adhesive strength to aluminum foil, and suppressing delamination after retort sterilization.

[0028] Hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule is preferably subjected to a urethane reaction with a polyisocyanate together with a polyester polyol. When (a1) reacts with the polyisocyanate and is introduced into polyester urethane polyol (A), carboxy groups are introduced as side chains into the resin skeleton, and the carboxy groups present as side chains are thought to improve adhesion to metals. In the urethanization reaction, the amount of (a1) 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, in the polyester urethane polyol (A), the mass of the structural units derived from hydroxycarboxylic acid (a1) is preferably 0.05% by mass or more, more preferably 1.0% by mass or more, and preferably 5.0% by mass or less, more preferably 3.0% by mass or less, based on the mass of the structural units derived from the polyester polyol. It may be 0.05 to 5.0% by mass, or may be 0.1 to 3.0% by mass. A proportion of the structural units derived from (a1) of 0.05% by mass or more improves metal adhesion, and a proportion of 5.0% by mass or less suppresses the generation of fine particles, which are self-reaction products of (a1), resulting in an excellent appearance, which is preferable.

[0029] (Polyisocyanate) Examples of polyisocyanates constituting the polyesterurethane 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 sanitation, isophorone diisocyanate is preferred.

[0030] (Hydroxycarboxylic acid (c1) having one hydroxy group and two or more carboxy groups in one molecule, carboxylic acid anhydride (c2) having one or more carboxy groups in one molecule) From the viewpoint of improving acid resistance, the polyester urethane polyol (A) preferably has, at the molecular end, a structural unit derived from at least one selected from the group consisting of hydroxycarboxylic acids (c1) having one hydroxy group and two or more carboxy groups in one molecule, and carboxylic acid anhydrides (c2) having one or more carboxy groups in one molecule. By having a structural unit derived from (c1) or (c2) at the molecular end of the polyesterurethane polyol (A), a carboxyl group is introduced at the molecular end. The carboxyl group introduced at the molecular end interacts with the metal surface through polar attraction, coating the metal surface. This prevents acid components from the contents that have penetrated the material from reacting with the metal surface, maintaining adhesion and providing excellent acid resistance. The polyester urethane polyol (A) having a structural unit derived from (c1) or (c2) at the molecular terminal can be obtained as a reaction product of a polyester polyol, the above (a1), a polyisocyanate, and a compound selected from the group consisting of the above (c1) and (c2).

[0031] Examples of (c1) include malic acid and citric acid. (c1) is preferably added during the urethanization reaction of the above-mentioned polyester polyol and a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per molecule with a polyisocyanate. Because the number of hydroxy groups per molecule of (c1) is one, the urethanization reaction terminates upon reaction of the hydroxy group of (c1) with the isocyanate group of the polyisocyanate, and structural units derived from (c1) can be introduced into the molecular terminals of the polyester urethane polyol (A).

[0032] An example of (c2) is trimellitic anhydride. (c2) is preferably added during the urethane reaction of the above-mentioned polyester polyol and a polyol containing a hydroxycarboxylic acid (a1) having two or more hydroxy groups and two or more carboxy groups per 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), allowing structural units derived from (c2) to be introduced into the molecular terminals of the polyester urethane polyol (A).

[0033] In the urethanization reaction, the blending amount of (c1) and (c2) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, based on the mass of the polyester polyol. It is also preferably 3.0% by mass or less, more preferably 2.0% by mass or less. That is, the proportion of structural 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, based on the mass of structural units derived from the polyester polyol, and is 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 structural 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 end of the pouch after hot water treatment is suppressed. When the content is 3.0% by mass or less, the amount of hydroxy groups at the molecular terminals of the polyesterurethane polyol (A) is sufficient, and sufficient crosslinking is formed in the reaction with a curing agent containing a polyisocyanate, which will be described later, and heat resistance can be maintained.

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

[0035] From the viewpoint of achieving both adhesive strength and coatability, the polyester urethane polyol has a number average molecular weight of preferably 2,000 or more, more preferably 5,000 or more. It is also preferably 40,000 or less, more preferably 20,000 or less, and even more preferably 15,000 or less, and may be, for example, 2,000 to 40,000, 5,000 to 20,000, or 5,000 to 15,000. Within the above ranges, the viscosity becomes appropriate, resulting in excellent coatability and excellent adhesive strength after curing. From the viewpoint of content resistance and heat resistance, the polyesterurethane polyol preferably has an acid value of 3 to 30 mgKOH / g, more preferably 3 to 20 mgKOH / g, and even more preferably 3 to 10 mgKOH / g. When the acid value is within the above range, excellent adhesive strength can be maintained even when the adhesive is stored for a long period of time after being filled with acidic content. Furthermore, since the amount of hydroxyl groups in the polyesterurethane polyol is not insufficient, the crosslink density of the cured adhesive can be sufficient, and excellent heat resistance can be maintained.

[0036] The hydroxyl value of the polyesterurethane polyol is preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and even more preferably 15 mgKOH / g or less. Also, it is preferably 1 mgKOH / g or more, and may be, for example, 1 to 30 mgKOH / g, 1 to 25 mgKOH / g, or 1 to 15 mgKOH / g.

[0037] [Other polyols] The base resin in the present invention may contain a polyol component other than the polyesterurethane 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 fluorine-containing polyols that do not contain (a1). Furthermore, the adhesive may contain a polyol derived from vegetable oil, such as a castor oil-based polyol. The use of a vegetable oil-derived polyol can increase the biomass content of the adhesive and reduce the burden on the environment.

[0038] [Particle number concentration measurement] In the base agent, the particle number concentration measured by dynamic light scattering is preferably 4000 particles / mL or less, more preferably 2000 particles / mL or less, based on the solid content mass, of particles having a particle diameter of 25 μm or more. If the concentration is within the above range, it is possible to prevent bubbles from forming and causing poor appearance when the base agent is used as a package. The number concentration of particles having a particle diameter of 25 μm or more based on the solid 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 automatic dynamic light scattering particle measurement system, the particle size and particle number concentration (particles / mL) of insoluble particles in the diluted base solution are measured. Next, the particle number concentration (particles / mL) of particles with a particle size of 25 μm or more is calculated from the resulting histogram (vertical axis: particle number concentration (particles / mL), horizontal axis: particle size). Measurements are performed three times, and the number concentration of particles with a particle size of 25 μm or more is calculated based on the solid mass using 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 base agent before dilution (mass%) a1: Number concentration of particles with a particle diameter of 25 μm or more in the first measurement (particles / mL) a2: Number concentration of particles with a particle diameter of 25 μm or more in the second measurement (particles / mL) a3: Number concentration of particles with a particle diameter of 25 μm or more (particles / mL) in the third measurement b: Number concentration of particles with a particle diameter of 25 μm or more in the dilution solvent (particles / mL) c: Number concentration of particles with a particle diameter of 25 μm or more in the added solvent during synthesis (particles / mL) n: Dilution ratio (times)

[0039] The dynamic light scattering automatic particle measurement system that can be used is the "SLS-2000" (manufactured by Particle Measurement Systems, equipped with a LiQuiazIIE20P sensor). Measurement conditions may be a measurement atmosphere of 25°C and a flow rate of 20 mL / min. Measurement values are output as a histogram with particle number concentration (particles / mL) on the vertical axis and particle diameters within a certain range on the horizontal axis, and the particle number concentration (particles / mL) with a particle diameter of 25 μm or more can be calculated from the histogram.

[0040] <Curing agent> The curing agent in the present invention contains a polyisocyanate (B). Examples of the polyisocyanate (B) include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, araliphatic diisocyanates, trifunctional or higher polyisocyanate monomers, dimers, trimers, biurets, or allophanates derived from the above diisocyanates or trifunctional or higher polyisocyanate monomers, and polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and the above diisocyanates or trifunctional or higher polyisocyanate monomers. Among these, aliphatic diisocyanates, alicyclic diisocyanates, araliphatic diisocyanates, and derivatives thereof 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-isocyanatomethyl-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(isocyanatomethyl)cyclohexane, and 1,3-bis(isocyanatomethyl)cyclohexane.

[0043] Examples of aromatic diisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0044] Examples of the aromatic aliphatic diisocyanate include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, a mixture of 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, and a mixture of 1,3-bis(1-isocyanato-1-methylethyl)benzene and 1,4-bis(1-isocyanato-1-methylethyl)benzene.

[0045] Examples of tri- or higher functional polyisocyanate monomers include organic triisocyanates such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanate benzene, and 2,4,6-triisocyanate toluene; and organic tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.

[0046] The polyisocyanate (B) may be a polyisocyanate having a urethane bond obtained by adding a polyol to the above-mentioned polyisocyanate. Examples of the polyol 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 polyester polyols, polyether ester polyols, polyester amide polyols, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxy alkanes, castor oil, and polyurethane polyols, each having a molecular weight of 200 to 20,000.

[0047] The polyisocyanate (B) may be used alone or in combination of two or more. Among them, from the viewpoints of hygiene, flexibility, and heat resistance, preferred are alicyclic diisocyanates, aliphatic diisocyanates, or derivatives thereof, more preferred are those containing at least one selected from the group consisting of an adduct of isophorone diisocyanate and an adduct of xylylene diisocyanate, even more preferred are those containing at least one selected from the group consisting of a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane, and particularly preferred are those containing a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane.

[0048] The polyisocyanate (B) preferably contains 10 to 90 mass% of a reaction product of isophorone diisocyanate and trimethylolpropane and 10 to 90 mass% of a reaction product of xylylene diisocyanate and trimethylolpropane, based on the solid content mass of the polyisocyanate (B), and more preferably contains 40 to 80 mass% of a reaction product of isophorone diisocyanate and trimethylolpropane and 20 to 60 mass% of a 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 improve hot water resistance. Examples of silane coupling agents that can be used include those having functional groups such as vinyl groups, epoxy groups, amino groups, imino groups, and mercapto groups, as well as functional groups such as methoxy groups and ethoxy groups. More specifically, examples include trialkoxysilanes having a vinyl group, such as vinyltrimethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group, such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; and trialkoxysilanes having a glycidyl group, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. From the standpoint of hygiene and hot water resistance, the amount of silane coupling agent added 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, antifungal agents, thickeners, plasticizers, pigments, fillers, etc. Also, known catalysts, additives, etc. may be contained to adjust the curing reaction.

[0051] <Organic solvents> The reactive adhesive of the present invention can be used as either a solvent-based or solventless type, and can 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 room temperature to 100°C, it can be used as a solvent-free type. If the viscosity of the adhesive is higher than the above range, it can be diluted with a solvent and used as a solvent-based type. As the organic solvent, for example, those inactive to isocyanates, such as esters such as ethyl acetate; ketones such as methyl ethyl ketone; and aromatic hydrocarbons such as toluene and xylene, are preferably used.

[0052] <Preparation of reactive adhesive> The reactive adhesive of the present invention can be produced by mixing a base agent containing a polyesterurethane polyol (A) with a curing agent containing a polyisocyanate (B) in an appropriate blending ratio. When blending the base agent and the curing agent, the ratio (NCO / OH) of the number of isocyanato groups in the curing agent to the number of hydroxyl groups in the base agent is preferably in the range of 1.0 to 5.0. Within this range, sufficient crosslink density is achieved, resulting in excellent adhesive strength. This is also preferred from the viewpoints of curing time, hygiene, and economy.

[0053] The adhesive of the present invention can be used by applying it to the film surface using a solvent-based or solventless laminator, allowing the solvent to evaporate in the case of a solvent-based adhesive, and then laminating the adhesive surfaces together in the case of a solventless adhesive, and curing at room temperature or elevated temperature. It is generally convenient to apply the adhesive in an amount of 1.0 to 2.0 g / m² (dry solids) for a solvent-based adhesive, and 2.0 to 5.0 g / m² (dry solids) for a solvent-based adhesive.

[0054] <Laminates, packaging materials> 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 that is a cured product of the reactive adhesive, and a second substrate layer. For example, the laminate can be formed by applying the reactive adhesive to one side of the first substrate using a dry laminator, then laminating the second substrate, and curing the adhesive layer located between the two substrates at room temperature or under heat. The laminate of the present invention may further include another substrate disposed via an adhesive layer, etc., and may have 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 formed using these laminates. When the reactive adhesive contains an organic solvent, a drying step may be provided as needed. The thickness of the laminate may be 10 μm or more, and the amount of adhesive applied after drying may be 1 to 10 g / m 2 may be.

[0055] [Base material] The substrate is not particularly limited, and examples thereof include plastic films, papers, gas barrier substrates, sealants, etc. that are commonly used in packaging applications, and the first substrate and the second substrate may be the same or different types. The plastic film may be a film of a thermoplastic resin or a thermosetting resin, with a thermoplastic resin film being preferred. Examples of thermoplastic resins include polyolefin, polyester, polyamide, polystyrene, vinyl chloride resin, vinyl acetate resin, ABS resin, acrylic resin, acetal resin, polycarbonate resin, 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 preferable from an economical point of view.

[0057] The sealant has heat-sealing properties, and examples thereof 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-sealing properties. The thickness of the sealant may be 10 to 60 μm or 15 to 40 μm. Furthermore, the sealant may be provided with unevenness with a height difference of 5 to 20 μm to impart slipperiness and tearability to the package. The sealant may have a vapor-deposited layer of aluminum, silica, alumina, or the like in addition to aluminum foil.

[0058] 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, designs, etc. is formed for decoration, indication of contents, expiration date, manufacturer, seller, etc., or for the purpose of adding aesthetic appeal, 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. The thickness of the printed layer may be 0.1 to 10 μm, 1 to 5 μm, or 1 to 3 μm. [Example]

[0059] The present invention will be specifically explained below with reference to examples and comparative examples. The present invention is not limited to the following examples as long as it does not depart from the gist of the invention. Unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass". Blank spaces in the tables indicate that no ingredients were blended.

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

[0061] <Acid value (AV) measurement> Approximately 1 g of sample was precisely weighed into a stoppered Erlenmeyer flask and dissolved in 100 ml of methyl ethyl ketone. Phenolphthalein test solution was added as an indicator and the solution was left to stand for 30 seconds. The solution was then titrated with 0.1 N alcoholic potassium hydroxide solution until it turned a pale pink color, and the acid value (mgKOH / g) was calculated using the following formula. Acid value (mgKOH / g)=(5.611×a×F) / S Where S: sample amount (g) a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml) F: Potency of 0.1N alcoholic potassium hydroxide solution

[0062] <Hydroxyl value (OHV)> Approximately 1 g of sample was precisely weighed into a stoppered Erlenmeyer flask, and exactly 5 ml of acetylating agent (20 g of acetic anhydride dissolved in pyridine to a volume of 100 ml) was added. The mixture was heated and stirred at 110°C for approximately 2 hours. The stoppered Erlenmeyer flask was then cooled with water, and 1.2 mL of distilled water was added, followed by heating for an additional 5 minutes. Phenolphthalein test solution was added as an indicator, and the mixture was 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 (mgKOH / g) was calculated using the following formula: Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.05} / S] + D Where S: sample amount (g) a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml) b: Amount of 0.1N alcoholic potassium hydroxide solution consumed in the blank experiment (ml) F: Potency of 0.1N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

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

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

[0065] [Table 1]

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

[0067] (Polyester urethane polyols A2 to A11, A13 to A23) Solutions of polyesterurethane polyols A2 to A11 and A13 to A23 were obtained in the same manner as in the preparation of polyesterurethane polyol A1, except that the blending composition of the raw materials was changed to that shown in Table 2.

[0068] (Polyester urethane polyol A12) 100 parts of polyester polyol (pes-1) were charged with 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, and the mixture was subjected to a urethane reaction at 90°C for 3 hours. 40 parts of ethyl acetate was added, and the mixture was stirred at 50°C for 1 hour and filtered through a 200-mesh polyethylene filter to obtain a polyester urethane polyol A12 solution.

[0069] [Table 2]

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

[0071] <Preparation of polyisocyanate> (Polyisocyanate B1) 35 parts of a TMP adduct of IPDI, 35 parts of a TMP adduct of XDI, and 30 parts of ethyl acetate were mixed at 40° C. under a nitrogen atmosphere for 30 minutes to obtain a polyisocyanate B1 solution.

[0072] (Polyisocyanates B2 to B5) Except for changing the raw materials to those listed in Table 3, the same procedure as for polyisocyanate B1 was carried out to obtain polyisocyanate B2 to B5 solutions.

[0073] [Table 3]

[0074] <Production of reactive adhesives> [Examples 1 to 23, Comparative Examples 1 to 7] Adhesives were obtained by blending the base agent, curing agent, and organic solvent according to the formulations shown in Tables 4 and 5. When the base agent did not contain additives, a polyesterurethane polyol solution was used as the base agent. When the base agent contained additives, a polyesterurethane polyol solution to which the additives had been blended was used as the base agent.

[0075] <Measurement of particle number concentration of main agent> The base solution was diluted with ethyl acetate to a viscosity of approximately 50 mPa·s at 25°C. The particle size and particle number concentration (particles / mL) of the insoluble particles contained in the diluted base solution were measured using an automatic dynamic light scattering particle measurement system "SLS-2000" (Particle Measurement Systems, equipped with a 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 at a fixed range on the horizontal axis. Three measurements were performed for each sample, and the measured values were calculated as follows to determine the particle number concentration (particles / mL) of particles 25 μm or larger. The particle number concentrations (particles / mL) of particles 25 μm or larger in diameter for the dilution solvent and the additive solvent used during synthesis were calculated as described above. Particle number concentration = [{Σ(a1+a2+a3) / 3×n]-{b×(n-1)}]×(X / 100) -c×(100-X / 100) Where, X: solid content concentration of the base agent before dilution (mass%) a1: Number concentration of particles with a particle diameter of 25 μm or more in the first measurement (particles / mL) a2: Number concentration of particles with a particle diameter of 25 μm or more in the second measurement (particles / mL) a3: Number concentration of particles with a particle diameter of 25 μm or more (particles / mL) in the third measurement b: Number concentration of particles with a particle diameter of 25 μm or more in the dilution solvent (particles / mL) c: Number concentration of particles with a particle diameter of 25 μm or more in the added solvent during synthesis (particles / mL) n: Dilution ratio (times)

[0076] <Evaluation of reactive adhesives> (Preparation of a four-layer laminate) A four-layer laminate consisting of polyethylene terephthalate (PET) film (E5102 manufactured by Toyobo Co., Ltd., thickness 12 μm) / aluminum (AL) foil (manufactured by Toyo Aluminum Co., Ltd., thickness 9 μm) / nylon (NY) film (ON-RTBC manufactured by Unitika Co., Ltd., double-sided corona treatment, thickness 15 μm) / unstretched polypropylene (CPP) film (ZK-207 manufactured by Toray Industries, thickness 70 μm, surface corona discharge treatment) was prepared using the method described below. First, the reactive adhesive obtained in the Examples and Comparative Examples was applied to a polyethylene terephthalate film at room temperature using a laminator, the solvent was evaporated, and the coated surface was then bonded to aluminum foil. Next, the reactive adhesive was similarly applied to the other side of the aluminum foil, the solvent was evaporated, and the coated surface was then bonded to a nylon film. Next, the reactive adhesive was similarly applied to the other side of the nylon film, the solvent was evaporated, and the coated surface was then bonded to an unstretched polypropylene film. The laminate was then produced by incubating at 40°C for 4 days. The coating amount of each adhesive layer after drying was 4.5 g / m. 2 It was decided.

[0077] (acid resistance test) The resulting laminate was used to prepare pouches measuring 9 cm x 12 cm, which were then vacuum-filled with a mixture of 6.7 parts each of vinegar, ketchup, and salad oil, each with a concentration of 4.2% or higher. The pouches were then sterilized in hot water at 10 rpm, 135°C, and 0.3 MPa for 30 minutes. The contents were then discarded, thoroughly washed, and air-dried. The following day, 15 mm x 300 mm test specimens were prepared and measured for the laminate strength (N / 15 mm) between the NY film and the AL foil using a tensile tester at a temperature of 20°C and a relative humidity of 65% using a T-peel tester at a peel rate of 30 cm / min. The results were 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: Less than 4.5N / 15mm

[0078] (Flexed film extreme retort test (Erichsen retort evaluation)) A 6 cm x 11 cm piece of film was cut from the resulting laminate, and an 8 mm deep hemispherical depression was formed in the center using an Erichsen tester. The film with the depression formed was cut in half with a cutter to obtain a 3 cm x 11 cm piece of film. Next, the 3 cm x 11 cm piece of film was placed in a retort pouch filled with water and vacuum sealed. The pouch was then subjected to hot water sterilization at 10 rpm, 130°C, 3 MPa for 30 minutes. The film after hot water sterilization was visually observed for delamination at the depression and evaluated according to the following criteria. A: No delamination B: Delamination in the recessed area is greater than 0% and less than 5% by area, and there is no delamination outside the recessed area C: Delamination in the recessed area is more than 5% and less than 40% by area, and there is no delamination outside the recessed area D: Delamination in the recessed area is more than 40% and less than 80% E: Delamination in the recessed area exceeds 80% of the area. Delamination in the recessed area is greater than 40% but less than 80% by area, and delamination is present in areas other than the recessed area (unusable)

[0079] (Appearance evaluation) A film measuring 10 cm x 10 cm was cut out from the obtained laminate, and the number of bubbles was visually counted and evaluated according to the following criteria. A: 0 to 1 bubble B: 2-3 bubbles C: 3 or more bubbles

[0080] (Extract evaluation) PET film (E5102 manufactured by Toyobo Co., Ltd., thickness 12 μm) and LLDPE (TUX-FCD manufactured by Mitsui Chemicals Tocello Co., Ltd., thickness 50 μm) were bonded together using a reactive adhesive (coating amount 3.5 g / m 2The laminate was then laminated using a 100°C (100% ethanol) filter and aged at 40°C for 96 hours. The resulting laminate was placed in a migration cell (manufactured by FABES Forchungs-Gmbh), and 25 ml of isooctane was added to the top of the migration cell as a food simulant. The mixture was then heated in an oven at 100°C for 1 hour and then stored at 60°C for 10 days. After removing 25 ml of isooctane, the mixture was concentrated to 1 ml, and the amount of silane coupling agent was quantified using GC-MS. The amount of extraction was evaluated according to the following criteria. A: 0.15μg / kg or less B: Over 0.15μg / kg and 2.00μg / kg or less C: Over 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 good results in the Erichsen retort test. In particular, when the blending amount of hydroxycarboxylic acid (a1) was 0.1 to 3.0% by mass based on the mass of the polyester polyol, the Erichsen retort test improved, acid resistance (AL / NY laminate strength after retort) improved, and fine particles in the base resin were suppressed, resulting in excellent laminate film appearance. Furthermore, by incorporating structural units derived from hydroxycarboxylic acid (c1) having one hydroxy group and two or more carboxy groups per molecule or carboxylic anhydride (c2) having one or more carboxy groups per molecule, the Erichsen retort test resistance was further improved. When the combined blending amount of (c1) and (c2) was 0.1 to 2.0% by mass based on the mass of the polyester polyol, both the Erichsen retort test and acid resistance were excellently achieved. Furthermore, by including a reaction product of isophorone diisocyanate and trimethylolpropane, and a reaction product of xylylene diisocyanate and trimethylolpropane in the curing agent (B), the composition achieved excellent compatibility in appearance, acid resistance, and Erichsen retort test. By including a silane coupling agent content of 0.1 mass% or less based on the mass of polyesterurethane polyol (A), the amount of silane coupling agent extracted was reduced, and both Erichsen retort test and acid resistance (AL / NY laminate strength after retort) were achieved.

Claims

1. A reactive adhesive comprising a base agent and a curing agent, the base resin 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, a structural unit derived from a polyester polyol, and a structural unit derived from a polyisocyanate; the content of the structural units derived from the hydroxycarboxylic acid (a1) is 0.05 to 5.0 mass% based on the mass of the structural units derived from the polyester polyol, the curing agent comprises a polyisocyanate (B), A reactive adhesive, wherein the content of a silane coupling agent in the reactive adhesive is 2.00 μg / kg or less.

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

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

4. A reactive adhesive as described in claim 1, wherein the content of constituent units derived from the hydroxycarboxylic acid (a1) is 0.1 to 3.0 mass % based on the mass of constituent units derived from the polyester polyol.

5. The reactive adhesive according to claim 1, wherein the polyester urethane polyol (A) has, at its molecular terminal, a structural unit derived from at least one selected from the group consisting of hydroxycarboxylic acids (c1) having one hydroxy group and two or more carboxy groups in one molecule, and carboxylic acid anhydrides (c2) having one or more carboxy 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 hydroxy groups and two or more carboxy groups in one molecule, a polyisocyanate, and a compound selected from the group consisting of a hydroxycarboxylic acid (c1) having one hydroxy group and two or more carboxy groups in one molecule and a carboxylic acid anhydride (c2) having one or more carboxy groups in one molecule, and the total amount of (c1) and (c2) is 0.1 to 2.0 mass% based on the mass of the polyester polyol.

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

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

9. 2. The reactive adhesive according to claim 1, wherein the base agent has a number concentration of particles having a particle diameter of 25 μm or more based on the solid content mass, calculated based on particle number concentration measurement using the dynamic light scattering method described below, of 4000 particles / mL or less. <Method for measuring the number concentration of particles with a particle diameter of 25 μm or more> Using a dynamic light scattering particle automatic measurement system, the particle size and particle number concentration (particles / mL) of insoluble particles in the diluted base solution are measured. Next, from the obtained 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 more is calculated. The measurement is carried out three times, and the number concentration of particles with a particle size of 25 μm or more based on the solid content mass is calculated using the obtained values 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 base agent before dilution (mass%) a1: Number concentration of particles with a particle diameter of 25 μm or more in the first measurement (particles / mL) a2: Number concentration of particles with a particle diameter of 25 μm or more in the second measurement (particles / mL) a3: Number concentration of particles with a particle diameter of 25 μm or more (particles / mL) in the third measurement b: Number concentration of particles with a particle diameter of 25 μm or more in the dilution solvent (particles / mL) c: Number concentration of particles with a particle diameter of 25 μm or more in the added solvent 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 mass % or less based on the mass of the polyesterurethane polyol (A).

11. A laminate having an adhesive layer formed from the reactive adhesive according to any one of claims 1 to 10 between a first substrate and a second substrate.

12. A package comprising the laminate according to claim 11.

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