Reactive adhesives, laminates, and packaging materials

Abstract

To provide a reactive adhesive that has excellent storage stability and desorption properties, and does not experience a decrease in strength over time even when the contents contain acidic components, alkaline components, volatile components, surfactant components, etc., and that is excellent in storage stability, recyclability and content resistance, as well as laminates and packaging materials that use the reactive adhesive and achieve storage stability, recyclability and content resistance. [Solution] A reactive adhesive for forming the detachable adhesive layer in a laminate having a base material and a detachable adhesive layer, wherein the base material can be separated and recovered by detaching the detachable adhesive layer, It contains a polyol main component and an isocyanate curing agent. The polyol main component includes polyester polyol (A), A reactive adhesive in which polyester polyol (A) satisfies all of the following conditions (1) to (3). (1) A reaction product or derivative thereof of a polybasic acid or its derivative and a polyhydric alcohol, wherein the polyhydric alcohol contains 0.1 to 2.5 moles of an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups in the polyhydric alcohol. (2) The number-average molecular weight is between 4,500 and 20,000. (3) The acid value is 10 mg KOH / g or higher.

Description

Technical Field

[0001] The present invention relates to a reactive adhesive, a laminate, and a packaging material.

Background Art

[0002] In recent years, packages made from plastic films, plastic bottles, and other plastic products have been discarded as garbage in the ocean, causing environmental pollution problems. These plastic products are decomposed in seawater into submicron-sized fragments (microplastics) that float in the seawater. There is concern that these microplastics are ingested by marine organisms such as fish and concentrated in their bodies, which may also affect the health of seabirds and humans who consume these marine organisms as food.

[0003] Therefore, in recent years, as an adhesive used when laminating a plastic film in a packaging material, an adhesive that can be detached from the film using a detachment liquid such as water or an alkaline aqueous solution has been used to separate and recover the plastic film from the packaging material and recycle it.

[0004] As a detachable adhesive composition used for a packaging material that enables recycling of a plastic film with such a specific treatment liquid, for example, Patent Document 1 discloses a two-component curable adhesive containing an isocyanate composition and an isocyanate-reactive composition containing an active hydrogen group-containing compound, and a reactive adhesive obtained by adding a resin or a low molecular compound having an acidic group to the isocyanate-reactive composition. Further, Patent Document 2 discloses a reactive adhesive containing a polyol composition and a polyisocyanate, and the polyol composition contains a polyester polyol and a rosin-modified resin having a hydroxyl group and an acidic group.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, Patent Document 1 does not describe the problem of the present invention, which is to achieve both desorption properties and resistance to contents containing acidic components, alkaline components, volatile components such as fragrances, and surfactant components, such as those found in shampoos and conditioners. Furthermore, adhesives containing isocyanate reactive compositions that include polyester polyols satisfying the number average molecular weight (Mn) or the content of aliphatic alcohols having quaternary carbon atoms and trivalent or higher hydroxyl groups described in Patent Document 1 make it difficult to solve the problem of resistance to the contents from the viewpoint of the strength of the adhesive layer. Patent Document 2 states that by using a reactive adhesive containing a polyester polyol and a polyol containing a rosin-modified resin having hydroxyl and acidic groups, both desorption properties and the aforementioned content resistance can be achieved. On the other hand, when a rosin-modified resin having hydroxyl and acidic groups is used, the storage stability of the polyol resin containing the rosin-modified resin deteriorates, and the processability of the reactive adhesive containing the polyol resin deteriorates, resulting in the inability to achieve the original physical properties, which remains a problem. Here, storage stability refers to the property that the viscosity of the resin does not change significantly even when stored for a long period of time without use. In other words, if the storage stability is poor, the viscosity of the resin will increase or decrease significantly over time.

[0007] Therefore, the object of the present invention is to provide a reactive adhesive that has excellent storage stability and desorption properties, and does not experience a decrease in strength over time even when the contents contain acidic components, alkaline components, volatile components, surfactant components, etc., and that is excellent in storage stability, recyclability and content resistance, as well as laminates and packaging materials that use the reactive adhesive and achieve storage stability, recyclability and content resistance. [Means for solving the problem]

[0008] The present invention relates to the following [1] to [8].

[0009] [1] A reactive adhesive for forming the detachable adhesive layer in a laminate having a base material and a detachable adhesive layer, wherein the base material can be separated and recovered by detaching the detachable adhesive layer, It contains a polyol main component and an isocyanate curing agent. The polyol main component includes polyester polyol (A), A reactive adhesive in which polyester polyol (A) satisfies all of the following conditions (1) to (3). (1) A reaction product or derivative thereof of a polybasic acid or its derivative and a polyhydric alcohol, wherein the polyhydric alcohol contains 0.1 to 2.5 moles of an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups in the polyhydric alcohol. (2) The number-average molecular weight is between 4,500 and 20,000. (3) The acid value is 10 mg KOH / g or higher.

[0010] [2] The reactive adhesive according to [1], wherein the polyester polyol (A) has a methylene chain having 6 or more carbon atoms derived from a polybasic acid or a derivative thereof or a polyhydric alcohol.

[0011] [3] The reactive adhesive according to [1] or [2], wherein the polybasic acid comprises an aliphatic polybasic acid having a methylene chain with 6 or more carbon atoms.

[0012] [4] A reactive adhesive according to any one of [1] to [3], wherein the polybasic acid contains terephthalic acid, and the content of terephthalic acid is 20 mol% or more based on the total amount of the polybasic acid or its derivatives.

[0013] [5] A reactive adhesive according to any one of [1] to [4], wherein the polyhydric alcohol contains an ether-bonded aliphatic diol.

[0014] [6] The polyester polyol (A) is a reaction product of a polybasic acid or its derivative and a polyhydric alcohol with an acidic compound, and the mass ratio of the acidic compound to an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups is 60:40 to 99:1. The reactive adhesive according to any one of [1] to [5].

[0015] [7] A laminate having an adhesive layer between at least two substrates, wherein the adhesive layer is a cured product of the reactive adhesive according to any one of [1] to [6].

[0016] [8] A packaging material using the laminate according to [7].

Effects of the Invention

[0017] According to the present invention, there are provided a reactive adhesive having excellent storage stability and peelability, and not exhibiting a decrease in strength over time even when the content contains components that cause significant damage to the adhesive layer, such as an acid component, an alkali component, a volatile component, or a surfactant component, and being excellent in storage stability, recyclability, and content resistance, and a laminate and a packaging material using the reactive adhesive and achieving all of storage stability, recyclability, and content resistance.

Modes for Carrying Out the Invention

[0018] The embodiments of the present invention will be described in detail below. However, the descriptions of the embodiments or requirements below are examples of the embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[0019] <<Reactive Adhesive>> The present invention relates to a reactive adhesive for forming a detachable adhesive layer in a laminate comprising a substrate and a detachable adhesive layer, wherein the substrate can be separated and recovered by detaching the detachable adhesive layer, the reactive adhesive comprising a polyol main component containing polyester polyol (A) and an isocyanate curing agent, wherein the polyester polyol (A) is a reaction product of a polybasic acid or a derivative thereof with a polyhydric alcohol or a derivative thereof, the polyhydric alcohol contains 0.1 to 2.5 ml of an aliphatic alcohol having a quaternary carbon atom and 3 or more hydroxyl groups, the number average molecular weight (Mn) of the polyester polyol (A) is 4,500 to 20,000, and the acid value (AVA) of the polyester polyol (A) is 10 mg KOH / g or more. By using a polyol main component containing the aforementioned polyester polyol (A) and an isocyanate curing agent, storage stability, alkali desorption properties, and content resistance can all be achieved.

[0020] The above effect is presumed to be due to the following mechanism. First, the ester bonds derived from the polyester polyol undergo partial hydrolysis, increasing its affinity for desorption solutions such as alkaline aqueous solutions and improving desorption properties. Furthermore, when the polyhydric alcohol constituting the polyester polyol (A) contains 0.1 to 2.5 moles of aliphatic alcohols having quaternary carbon atoms and three or more hydroxyl groups, branching within the polyester polyol (A) increases, resulting in a stronger adhesive layer formed by the curing of the reactive adhesive. This makes it less susceptible to damage even when the contents penetrate the substrate and reach the adhesive layer, allowing the adhesive strength to be maintained over a long period. Additionally, if the number-average molecular weight (Mn) of the polyester polyol (A) is within a predetermined range, a balance can be achieved between alkali desorption properties and content resistance. When the acid value of the polyester polyol (A) is 10 mgKOH / g or more, the affinity between the release liquid containing an alkaline component or the like and the reactive adhesive containing the polyester polyol (A) is improved due to the acidic groups. As a result, the decomposition or swelling of the reactive adhesive by the release liquid is promoted, and more excellent releasability is exhibited.

[0021] That is, the reactive adhesive of the present invention uses a polyester polyol (A) containing an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups in an amount of 0.1 to 2.5 mol% in the polyhydric alcohol. The number average molecular weight and acid value of the polyester polyol (A) are in a predetermined range, resulting in a synergistic effect, achieving both excellent releasability and resistance to contents containing components that cause significant damage to the adhesive layer.

[0022] <Polyol main agent> The polyol main agent in the present invention contains a polyester polyol (A).

[0023] [Polyester polyol (A)] The polyester polyol (A) is a reaction product of a polybasic acid or its derivative and a polyhydric alcohol or its derivative. It is important that an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups is contained in an amount of 0.1 to 2.5 mol% based on the total amount of all substances of the polyhydric alcohol. Further, the number average molecular weight (Mn) of the polyester polyol (A) is 4,500 to 20,000, and the acid value (AVA) of the polyester polyol (A) is 10 mgKOH / g or more, which is important. The polyester polyol (A) may be used alone, or two or more kinds having different molecular weights and glass transition temperatures may be used in combination from the viewpoints of coating properties and performance improvement.

[0024] (Polybasic acid or its derivative) Examples of the polybasic acids or their derivatives include aromatic ring-containing polybasic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, naphthalic acid, and naphthalic anhydride; aliphatic polybasic acids such as adipic acid, azelaic acid, suberic acid, sebacic acid, succinic acid, glutaric acid, decanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and itaconic anhydride; alkyl esters thereof; or mixtures thereof. Furthermore, monofunctional carboxylic acids such as benzoic acid, phenylacetic acid, and 3-phenylpropionic acid may be used in combination to adjust the molecular weight.

[0025] The polybasic acid or its derivative preferably includes a polybasic acid or its derivative having a methylene chain with 6 or more carbon atoms, and more preferably an aliphatic polybasic acid having a methylene chain with 6 or more carbon atoms. As a result, the polyester polyol (A) has a methylene chain with 6 or more carbon atoms derived from the polybasic acid or its derivative, which creates spacing between the ester groups present within the polyester polyol, suppressing hydrolysis and improving the resistance to contents. In addition, the flexibility of the reactive adhesive is increased, improving substrate adhesion and resistance to contents.

[0026] Aliphatic polybasic acids having a methylene chain with 6 or more carbon atoms include the aforementioned azelaic acid, suberic acid, sebacic acid, decanedicarboxylic acid, and dodecanedicarboxylic acid, among which sebacic acid is preferred from the viewpoint of content resistance.

[0027] The content of aliphatic polybasic acids having methylene chains with 6 or more carbon atoms is preferably 5 moles or more, more preferably 7 moles or more, even more preferably 10 moles or more, and preferably 40 moles or less, more preferably 35 moles or less, and even more preferably 30 moles or less, based on the total amount of the polybasic acids or their derivatives.

[0028] Furthermore, it is preferable that the polybasic acid also contains terephthalic acid. This increases the rigidity of the reactive adhesive and improves its resistance to the contents. The terephthalic acid content is preferably 20 moles or more, more preferably 23 moles or more, even more preferably 25 moles or more, and also preferably 55 moles or less, more preferably 50 moles or less, and even more preferably 45 moles or less, based on the total amount of polybasic acids or their derivatives.

[0029] (Polyhydric alcohol) Examples of the above-mentioned polyhydric alcohols include: polyhydric alcohols having alkylene oxide chains such as diethylene glycol, dipropylene glycol, triethylene glycol, dieopentyl glycol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, and polyether polyol; polyhydric alcohols without alkylene oxide chains such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3'-dimethylolheptane, and 1,9-nonanediol; polyhydric aliphatic alcohols having quaternary carbon atoms and 3 or more hydroxyl groups such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol; or mixtures thereof. Furthermore, polycarbonate polyols, polyolefin polyols, acrylic polyols, polyurethane polyols, or mixtures thereof may be used as the hydroxyl group component. Furthermore, monofunctional alcohols may be used in combination to adjust the molecular weight.

[0030] The polyhydric alcohol contains an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups in an amount of 0.1 to 2.5 moles, based on the total amount of polyhydric alcohols. This increases branching within the polyester polyol (A), making the adhesive layer stronger and improving its resistance to contents. The above content is preferably 0.1 moles or more, more preferably 0.3 moles or more, and even more preferably 0.5 moles or more. It is also preferably 2.5 moles or less, more preferably 2.3 moles or less, and even more preferably 2.0 moles or less. When the content of the aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups is 0.1 moles or more, the strength of the adhesive layer and its resistance to contents are improved, and when it is 2.5 moles or less, its desorption properties are improved. For example, the range of the content may be 0.1 to 2.5 moles, 0.3 to 2.3 moles, or 0.5 to 2.0 moles.

[0031] The polyhydric alcohol preferably contains a polyhydric alcohol having a methylene chain with 6 or more carbon atoms, and more preferably contains an aliphatic polyhydric alcohol having a methylene chain with 6 or more carbon atoms. As a result, the polyester polyol (A) has a methylene chain with 6 or more carbon atoms derived from the polyhydric alcohol, which creates spacing between the ester groups present inside the polyester polyol, suppressing hydrolysis and improving its resistance to contents.

[0032] Aliphatic polyhydric alcohols having a methylene chain with 6 or more carbon atoms include 1,6-hexanediol, 3,3'-dimethylolheptane, and 1,9-nonanediol, among which 1,6-hexanediol is preferred from the viewpoint of content resistance.

[0033] The content of polyhydric alcohols having methylene chains with 6 or more carbon atoms is preferably 5 moles or more, more preferably 7 moles or more, even more preferably 10 moles or more, and preferably 40 moles or less, more preferably 35 moles or less, and even more preferably 30 moles or less, based on the total amount of polyhydric alcohols.

[0034] Furthermore, the polyhydric alcohol preferably contains an ether-linked aliphatic diol. This improves the hydrophilicity of the reactive adhesive, promotes the decomposition or swelling of the reactive adhesive by the desorbing liquid, and exhibits superior desorbing properties. Examples of ether-linked aliphatic diols include the aforementioned diethylene glycol, dipropylene glycol, triethylene glycol, dieopentyl glycol, polyoxyethylene glycol, polyoxypropylene glycol, and polytetramethylene ether glycol. The content of the ether-linked aliphatic diol is preferably 5 moles or more, more preferably 7 moles or more, even more preferably 10 moles or more, and preferably 40 moles or less, more preferably 35 moles or less, and even more preferably 30 moles or less, based on the total amount of polyhydric alcohols.

[0035] The above-mentioned polybasic acids or their derivatives, and polyhydric alcohols may be used individually or in combination of two or more.

[0036] Polyester polyol (A) may be obtained by reacting a polyisocyanate with the hydroxyl groups in the polyester polyol to introduce urethane bonds. The presence of urethane bonds provides excellent heat resistance and adhesive properties. Examples of the above-mentioned polyisocyanates 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.

[0037] The polyester polyol (A) is preferably an acid-modified product obtained by acid-modifying some of the hydroxyl groups in the polyester polyol. For example, it may be obtained by reacting some of the hydroxyl groups in the polyester polyol with an acid compound to introduce carboxyl groups. Examples of the acidic compound include pyromellitic anhydride, phthalic anhydride, melitic anhydride, dodecenyl succinic anhydride, benzophenone tetracarboxylic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydromethylphthalic anhydride, methylhexahydrophthalic anhydride, and trimellitic anhydride esters. Examples of trimellitic anhydride esters include ethylene glycol bisanhydrotrimellitate and propylene glycol bisanhydrotrimellitate. Among these, trimellitic anhydride is preferred from the viewpoint of adjusting the molecular weight of the polyester polyol. Furthermore, the acidic compound used to acid-modify some of the hydroxyl groups in the polyester polyol may be used alone or in combination of two or more.

[0038] When polyester polyol (A) is an acid-modified product obtained by acid-modifying some of the hydroxyl groups in the polyester polyol, the mass ratio of the acidic compound used for acid modification to the aliphatic alcohol containing quaternary carbon atoms and 3 or more hydroxyl groups in the polyester polyol (A) is preferably 60:40 to 99:1, and more preferably 65:35 to 97:3. If the mass ratio is within the predetermined range, a balance can be achieved between alkali desorption and content resistance.

[0039] When the acid value (AVA) of polyester polyol (A) is 10 mg KOH / g or higher, when it comes into contact with a desorbing solution containing an alkaline component, the decomposition or swelling of the reactive adhesive by the desorbing solution is promoted, resulting in superior desorbing properties. From the viewpoint of improving desorbing properties, the acid value is preferably 15 mg KOH / g or higher, more preferably 20 mg KOH / g or higher, and even more preferably 25 mg KOH / g or higher.

[0040] The number average molecular weight (Mn) of the polyester polyol (A) is 4,500 to 20,000, which allows for a balance between the strength and substrate adhesion of the adhesive layer consisting of the main component containing the polyester polyol (A) and the isocyanate curing agent, achieving both desorption and content resistance. The number average molecular weight is preferably 5,000 or more, more preferably 5,500 or more, and even more preferably 6,000 or more. It is also preferably 18,000 or less, more preferably 16,500 or less, and even more preferably 15,000 or less. When the number average molecular weight of the polyester polyol (A) is 4,500 or more, desorption is improved. When it is 20,000 or less, substrate adhesion and content resistance are improved. For example, the range of the number average molecular weight may be 5,000 to 18,000, 5,500 to 16,500, or 6,000 to 15,000.

[0041] The content of polyester polyol (A) is preferably 60% by mass or more, and more preferably 70% by mass or more, in the polyol main component.

[0042] [Other ingredients that may be included in polyol-based formulations] The polyol main component may contain polyols other than polyester polyol (A) (hereinafter referred to as "other polyols"), to the extent that the effects of the present invention are not impaired. Examples of such other polyols include polyester polyols in which the raw material polyhydric alcohol contains less than 0.1 ml or more than 2.5 ml of aliphatic alcohol having quaternary carbon atoms and 3 or more hydroxyl groups, polyester polyols with a number average molecular weight of less than 4,500, polyester polyols with an acid value of less than 10 mg KOH / g, polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols.

[0043] The polyol main component may contain a compound having an acidic group (except for polyester polyol (A)) from the viewpoint of improving detachability. Examples of compounds having an acidic group include resins having an acidic group or low molecular weight compounds having an acidic group.

[0044] In the context of resins containing acidic groups, "resin" refers to a compound with a mass-average molecular weight of 1,000 or more. Examples of resins containing acidic groups include cellulose resins, urethane resins, polyamide resins, vinyl chloride / vinyl acetate copolymers, ketone resins, polyester resins, and (meth)acrylic resins. Examples of the acidic groups include carboxyl groups, phosphate groups, sulfo groups, sulfino groups, etc., or esters or salts thereof. Furthermore, radical copolymers such as styrene-(meth)acrylic resin, styrene-(anhydride)maleic acid resin, terpene-(anhydride)maleic acid resin, and acid-modified polyolefin resins can be used, which are copolymerized with polymerizable monomers having acidic groups, such as polymerizable monomers having carboxyl groups like itaconic acid, maleic acid, fumaric acid, and cinnamic acid; polymerizable monomers that are acid anhydrides like itaconic acid anhydride and maleic anhydride; polymerizable monomers having sulfonic acid groups like sulfonated styrene; and polymerizable monomers having sulfonamide groups like vinylbenzenesulfonamide.

[0045] Low molecular weight compounds with acidic groups refer to compounds with a molecular weight of less than 1,000. Examples of such compounds include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid; hydroxy acids such as lactic acid, malic acid, and citric acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, melitic acid, and cinnamic acid; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid; and aconite. Examples include tricarboxylic acids such as acids; oxocarboxylic acids such as pyruvic acid and oxaloacetate; carboxylic acid derivatives such as amino acids and nitrocarboxylic acids; and acid anhydrides such as trimellitic anhydride and pyromellitic anhydride.

[0046] The acid value of the polyol main component as a whole is preferably 5 to 130 mg KOH / g, more preferably 5 to 100 mg KOH / g. This range is excellent in terms of achieving both content resistance and desorption properties.

[0047] <Isocyanate hardening agent> The isocyanate curing agent in the present invention comprises a polyisocyanate, which is a compound having two or more isocyanate groups in one molecule. Examples of polyisocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, and aromatic aliphatic polyisocyanates. One type of polyisocyanate may be used alone, or two or more types may be used in combination.

[0048] Examples of aromatic polyisocyanates include aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and polyisocyanates such as allophanate-type, nurate-type, biuret-type, and adduct-type derivatives or complexes thereof derived from the above diisocyanates (e.g., polymethylene polyphenyl polyisocyanate).

[0049] Examples of aliphatic polyisocyanates include acyclic aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, and 1,2-butylene diisocyanate; alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (hereinafter referred to as isophorone diisocyanate); and polyisocyanates such as allophanate-type, nurate-type, biuret-type, and adduct-type derivatives derived from the above diisocyanates, or complexes thereof. Preferably, the derivatives are of the nurate type or adduct type. As the aliphatic polyisocyanate, polyisocyanates derived from hexamethylene diisocyanate (hereinafter also referred to as HDI) and / or polyisocyanates derived from isophorone diisocyanate are preferred, as they allow for a good balance between detachability and lamination properties.

[0050] Examples of aromatic aliphatic polyisocyanates include aromatic aliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω′-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanate-1-methylethyl)benzene or mixtures thereof; and polyisocyanates such as allophanate-type, nurate-type, biuret-type, adduct-type derivatives or complexes thereof derived from the above diisocyanates.

[0051] From the viewpoint of detachability, the polyisocyanate preferably includes at least one selected from the group consisting of aliphatic polyisocyanates and aromatic aliphatic polyisocyanates.

[0052] <<Manufacturing of reactive adhesives>> The reactive adhesive of the present invention can be manufactured by mixing a polyol main component and an isocyanate curing agent with an optional organic solvent, other components, etc. The ratio (NCO / OH) of the total number of isocyanate groups in the polyisocyanate contained in the isocyanate curing agent to the total number of hydroxyl groups in the polyol main component may be 0.3 to 10.0, preferably 0.3 to 7.0, and more preferably 0.5 to 5.0.

[0053] <Organic solvents> The reactive adhesive of the present invention may be either solvent-based or solvent-free, and may optionally contain an organic solvent. Preferably, the organic solvent is capable of dissolving the polyol composition and polyisocyanate described above, and is inert to the polyisocyanate. Examples of such organic solvents include ester solvents such as ethyl acetate and n-butyl acetate; ketone solvents such as methyl ethyl ketone; and aromatic hydrocarbon solvents such as toluene and xylene, which can be selected and used as appropriate.

[0054] <Other ingredients> (Silane coupling agent) 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 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. The amount of silane coupling agent is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on the solid content of the reactive adhesive.

[0055] (Phosphorus oxygenates or their derivatives) The reactive adhesive of the present invention may further contain a phosphorus oxyacid or a derivative thereof to enhance its acid resistance. The phosphorus oxyacid may be any oxyacid having at least one free oxyacid, such as phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and subphosphoric acid; or condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. A derivative of the phosphorus oxyacid may be any oxyacid obtained by partially esterifying the above phosphorus oxyacid with an alcohol while leaving at least one free oxyacid. The alcohol may be any aliphatic alcohol such as methanol, ethanol, ethylene glycol, and glycerin; or aromatic alcohol such as phenol, xylenol, hydroquinone, catechol, and phloroglycinol. Phosphorus oxygen acids or their derivatives may be used in combination of two or more types. The amount of phosphorus oxygen acids or their derivatives blended is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass, and even more preferably 0.05 to 1% by mass, based on the solid content of the reactive adhesive.

[0056] (Leveling agent or defoaming agent) The reactive adhesive of the present invention may further contain a leveling agent or an antifoaming agent to improve the appearance of the laminate. Examples of leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyether ester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymers, methacrylic copolymers, polyether-modified polymethylalkylsiloxane, alkyl acrylate copolymers, alkyl methacrylate copolymers, and lecithin. Examples of antifoaming agents include silicone resins, silicone solutions, and copolymers of alkyl vinyl ethers, alkyl acrylates, and alkyl methacrylates.

[0057] The reactive adhesive of the present invention may further contain additives such as antioxidants, ultraviolet absorbers, hydrolysis inhibitors, fungicides, thickeners, plasticizers, pigments, fillers, and catalysts for adjusting the curing reaction.

[0058] The viscosity of the reactive adhesive of the present invention is preferably 100 to 10,000 mPa·s at room temperature to 150°C, and preferably 100 to 10,000 mPa·s at room temperature to 100°C. If the viscosity is between 100 and 5,000 mPa·s, it can be used as a solvent-free type. If the viscosity of the reactive adhesive is higher than the above range, it may be diluted with an organic solvent.

[0059] <<Laminate>> The laminate of the present invention comprises an adhesive layer, which is a cured product of a reactive adhesive, between at least two substrates. The adhesive layer can be formed by laminating the reactive adhesive using a known method such as roll coating, and then curing it for about 24 hours to 1 week under conditions of 20 to 60°C. The amount of reactive adhesive applied after drying can be appropriately selected depending on the application, and is typically 1 to 10 g / m². 2 The range is preferably 1 to 2.5 g / m² for solvent-free type. 2 , solvent type: 1-6 g / m² 2 The range is as follows. The thickness of the adhesive layer is usually in the range of 1 to 6 μm, preferably 1 to 2.5 μm for solvent-free types and 1 to 6 μm for solvent-based types.

[0060] The adhesive layer in the laminate of the present invention exhibits excellent desorption properties to desorption liquids such as alkaline aqueous solutions, allowing the adhesive layer to be detached from the substrate, such as a resin substrate, thus enabling the substrate to be separated, recovered, and recycled. The desorption liquid is not particularly limited, but an alkaline aqueous solution is preferred. The alkaline aqueous solution is not particularly limited, and aqueous solutions of known basic compounds can be used, but preferably it is an aqueous solution containing at least one selected from the group consisting of sodium hydroxide and potassium hydroxide, for example, one at 25 to 120°C and 0.5 to 20% by mass is used. The alkaline aqueous solution may contain components such as organic solvents, surfactants, defoamers, and compatibilizers from the viewpoint of improving separation and recovery properties and improving compatibility when used as a recycled material.

[0061] The laminate of the present invention has excellent delamination properties and exhibits excellent resistance to contents without decreasing in strength over time, even when the contents contain acidic components, alkaline components, volatile components, surfactant components, etc. Therefore, it is particularly suitable for packaging materials and can be used not only for beverage and food packaging but also for refill pouches of liquid hair care products such as shampoos, hair conditioners, and hair rinses, liquid soaps such as body soaps and hand soaps, liquid detergents for clothes and dishes, finishing agents such as fabric softeners and bleaches, liquid cleaning agents for bathrooms and floors, liquid cosmetics, pharmaceuticals, etc.

[0062] (base material) The base material is preferably a resin layer. As the resin layer, for example, a plastic film commonly used in packaging laminates and a sealant can be used. Examples of plastic films used include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resin films such as polyethylene (PE) and polypropylene (PP); polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; and composites of these (e.g., nylon 6 / MXD6 / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6) or mixtures thereof. Among these, those with mechanical strength and dimensional stability are preferred.

[0063] Examples of sealants include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, unstretched polypropylene (CPP), 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. The above-mentioned plastic film and sealant may have a gas barrier layer which is a vapor-deposited layer of aluminum, silica, alumina, or the like.

[0064] The method for laminating the sealant is not particularly limited. Examples include a method of laminating the adhesive layer and the sealant film by heat (thermal lamination method), and a method of melting the sealant resin, extruding it onto the adhesive layer, and allowing it to cool and solidify to laminate (extrusion lamination method). These methods can be appropriately selected depending on the application. The thickness of the sealant is not particularly limited, but from the viewpoint of processability and heat sealability, it is preferably 10 to 200 μm, more preferably 15 to 150 μm. The sealant may be given slipperiness or tearability by having bumps and dips with a height difference of 5 to 20 μm.

[0065] The laminate of the present invention may have a printed layer. The printed layer is a layer that forms any printed pattern for purposes such as decoration, imparting aesthetic appeal, indicating contents, expiration date, manufacturer, or seller, and includes a solid print layer. The printed layer contains a colorant, a dispersant, and a binder resin, and may be formed from a single layer or multiple layers, and may have alkali desorption properties.

[0066] The laminate of the present invention may have a primer layer, or it may be a known desorbable layer. If the primer layer is desorbable, the primer layer is arranged in contact with the resin layer and may have a water-soluble resin or a compound having an acidic group.

[0067] The laminate of the present invention may have layers of metal foil, paper, etc. Examples of metal foil include aluminum foil. From an economic standpoint, the thickness of the metal foil is preferably about 3 to 50 μm. Examples of paper include natural paper and synthetic paper.

[0068] The structure of the laminate is not particularly limited, but from the viewpoint of resistance to contents and strength when the contents include acidic components, alkaline components, volatile components, surfactant components, etc., it is preferable to have a structure that includes a plastic film, metal foil or gas barrier layer, and a sealant. Specific configurations include, but are not limited to, the following. Biaxially oriented polypropylene (OPP) / adhesive layer / CPP, OPP / adhesive layer / AL vapor-deposited CPP, nylon (NY) / adhesive layer / LLDPE, NY / adhesive layer / CPP, PET / adhesive layer / NY / adhesive layer / LLDPE, NY / adhesive layer / PET / adhesive layer / LLDPE, PET / adhesive layer / AL vapor-deposited PET / adhesive layer / LLDPE, PET / adhesive layer / NY / adhesive layer / CPP, transparent vapor-deposited PET / adhesive layer / NY / adhesive layer / CPP, PET / adhesive layer / AL / adhesive layer / CPP, PET / adhesive layer / NY / adhesive layer / AL / adhesive layer / LLDPE, PET / adhesive layer / NY / adhesive layer / NY / adhesive layer / CPP, PET / adhesive layer / AL / adhesive layer / NY / adhesive layer / CPP. [Examples]

[0069] The present invention will be described in detail below with reference to 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.

[0070] <Molecular weight> The number-average molecular weight (Mn) was measured by GPC (gel permeation chromatography) and determined as the converted molecular weight using polystyrene as the standard substance. The measurement conditions are shown below. GPC device: Tosoh HLC(R)-8420GPC Columns: The following columns were used, connected in series. TSKgel SuperHM-M (manufactured by Tosoh Corporation) TSKgel SuperHM-L (manufactured by Tosoh Corporation) Detector: RI (Differential Refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 0.6mL / min

[0071] <Acid value> The acid value was measured according to the method described in JIS K 0070 (1992).

[0072] <Synthesis of intermediate polyester polyol (P)> (Synthesis of polyester polyol (P-1)) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 107 parts of 1,6-hexanediol, 82 parts of ethylene glycol, 211 parts of neopentyl glycol, 81 parts of diethylene glycol, 7 parts of trimethylpropanol, 281 parts of isophthalic acid, 95 parts of adipic acid, 211 parts of terephthalic acid, and 126 parts of sebacic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen atmosphere, and the esterification reaction was carried out. After a predetermined amount of water was distilled off and the reaction continued until the acid value was 5 or less, the pressure was gradually reduced, and the deglycolization reaction was carried out at a pressure of 1 mmHg or less for 5 hours to obtain the intermediate polyester polyol (P-1).

[0073] (Polyester polyol (P-2)~(P-16)) Except for changing the type and amount of polybasic acid or its derivative and polyhydric alcohol used in the synthesis as described in Table 1, the synthesis was carried out in the same manner as for polyester polyol (P-1) to obtain polyester polyols (P-2) to (P-16).

[0074] [Table 1]

[0075] The abbreviations used in Table 1 are shown below. TPA: Terephthalic acid IPA: Isophthalic Acid SeA: Sebacinic acid AdA: Adipic acid DA: Dimer acid "Tsunodyme 216" (an aliphatic dibasic acid manufactured by Tsukuno Foods Co., Ltd.) DEG: Diethylene glycol 1,6-HD:1,6-Hexanediol EG: Ethylene glycol NPG: Neopentyl Glycol TMP: Trimethylpropanol PETT: Pentaerythritol

[0076] (Synthesis of polyester polyol (P-17)) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 107 parts of 1,6-hexanediol, 82 parts of ethylene glycol, 211 parts of neopentyl glycol, 81 parts of diethylene glycol, 7 parts of trimethylpropanol, 281 parts of isophthalic acid, 95 parts of adipic acid, 211 parts of terephthalic acid, and 126 parts of sebacic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the predetermined amount of water was distilled off and the acid value was reduced to 5 or less, the reaction was continued, and the pressure was gradually reduced to 1 mmHg or less for 4 hours to perform a deglycolization reaction, yielding polyester polyol (P-17).

[0077] (Synthesis of polyester polyol (P-18)) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 107 parts of 1,6-hexanediol, 82 parts of ethylene glycol, 211 parts of neopentyl glycol, 81 parts of diethylene glycol, 7 parts of trimethylpropanol, 281 parts of isophthalic acid, 95 parts of adipic acid, 211 parts of terephthalic acid, and 126 parts of sebacic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen atmosphere, and the esterification reaction was carried out. After the predetermined amount of water was distilled off and the acid value was reduced to 5 or less, the reaction was continued, and the pressure was gradually reduced to 1 mmHg or less for 3 hours to perform a deglycolization reaction, yielding polyester polyol (P-18).

[0078] <Synthesis of polyester polyol (A)> 5.4 parts trimellitic anhydride was added to 100 parts polyester polyol (P-1), and the mixture was reacted at 180°C for approximately 2 hours. The mixture was then diluted with ethyl acetate until the non-volatile content reached 55%, yielding a solution of partially acid-modified polyester polyol (A-1) with a number-average molecular weight (Mn) of 7,500 and an acid value of 29.9 mg KOH / g.

[0079] (Polyester polyol (A-2)~(A-16)) Except for changing the type and amount of polyester polyol (P) and acidic compound used in the synthesis to those listed in Table 2, the synthesis was carried out in the same manner as for polyester polyol (A-1) to obtain polyester polyols (A-2) to (A-16).

[0080] <Synthesis of polyester polyol (A')> 100 parts of polyester polyol (P-13) were mixed with 5.4 parts of trimellitic anhydride, reacted at 180°C for approximately 2 hours, and then diluted with ethyl acetate until the non-volatile content reached 55% to obtain a solution of partially acid-modified polyester polyol (A'-1) with a number-average molecular weight (Mn) of 7,200 and an acid value of 29.9 mg KOH / g.

[0081] (Polyester polyol (A'-2)~(A'-7)) The synthesis was carried out in the same manner as for polyester polyol (A'-1), except that the type and amount of polyester polyol (P) and acidic compound used in the synthesis were changed to those listed in Table 2, to obtain solutions of polyester polyols (A'-2) to (A'-7).

[0082] [Table 2]

[0083] The abbreviations used in Table 2 are shown below. TMA: Trimellitus anhydride TMEG: Ethylene glycol bisanhydrotrimellitate

[0084] <Synthesis of other polyols> (Synthesis of other polyols (R-1)) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 108.4 parts of ethylene glycol, 386.7 parts of neopentyl glycol, 332.6 parts of isophthalic acid, and 372.3 parts of adipic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the reaction continued until a predetermined amount of water was distilled off and the acid value was 5 or less, the pressure was gradually reduced, and the deglycol reaction was carried out at 1 mmHg or less for 3 hours. Finally, the solution was diluted with ethyl acetate until the non-volatile content reached 50%, yielding a polyester polyol (R-1) solution with a number-average molecular weight (Mn) of 2,500 and an acid value of 0 mgKOH / g.

[0085] (Synthesis of other polyols (R-2)) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet, 282 parts of gum rosin and 107 parts of maleic anhydride were charged and heated at 180°C for 1 hour with stirring under a nitrogen stream to obtain the reaction mixture. Subsequently, gas chromatography-mass spectrometry of the reaction mixture was performed to confirm the progress of the reaction by the decrease in the detection peaks of gum rosin and maleic anhydride. When no further change was observed in the decrease of the detection peaks, the Diels-Alder addition reaction was considered complete. Next, 380 parts of benzoic acid, 122 parts of pentaerythritol, 66 parts of glycerin, 44 parts of ethylene glycol, and 0.05 parts of p-toluenesulfonic acid hydrate as a catalyst were added to the above reaction mixture and reacted at 240°C for 10 hours. After that, the mixture was diluted with ethyl acetate until the solid content concentration reached 50%, to obtain a solution of other polyol (R-2) with Mn 1,100 and an acid value of 25.2 mg KOH / g.

[0086] <Evaluation of polyol-based ingredients> (Evaluation of storage stability of polyol-based materials) Solutions of the obtained polyester polyols (A-1) to (A-16) and (A'-1) to (A'-7), along with solutions of other polyols (R-1) and (R-2), and ethyl acetate were mixed in the proportions shown in Table 3 to obtain a polyol main component with a solid content of 50%. The obtained polyol main component was left to stand for 2 months in an atmosphere of 40°C, and its viscosity was measured. The viscosity of the polyol-based material before standing in a 40°C atmosphere was defined as the [initial viscosity], and the viscosity after standing was defined as the [viscosity over time]. The storage stability was evaluated by comparing the [initial viscosity] and the [viscosity over time] and determining the rate of change. Viscosity measurements were performed using a B-type viscometer. The rate of change in viscosity from [initial viscosity] to [viscosity over time] was calculated using the following formula. Rate of change (%): ([Viscosity over time] - [Initial viscosity]) / [Initial viscosity] × 100

[0087] The rate of change over time for each polyol main component was calculated, and the storage stability was evaluated based on the following criteria. The results are shown in Table 3. S (Excellent): Less than 10% A (Good): 10% or more, less than 20% B (Acceptable): 20% or more, less than 30% C (impossible): 30% or more

[0088] <Polyisocyanate> (Synthesis of polyisocyanate (N-1)) BASONAT HB 100 (a biuret-type polyisocyanate derived from hexamethylene diisocyanate (hereinafter referred to as HDI), manufactured by BASF) was diluted with ethyl acetate to adjust the non-volatile content to 50% and NCO% = 11.7% to obtain a solution of polyisocyanate (N-1).

[0089] (Synthesis of polyisocyanate (N-2)) VESTANAT T1890 / 100 (a nurate-type polyisocyanate derived from isophorone diisocyanate (hereinafter referred to as IPDI), manufactured by Evonik Corporation) was diluted with ethyl acetate to adjust the non-volatile content to 50% and NCO% to 8.7% to obtain a solution of polyisocyanate (N-2).

[0090] (Synthesis of polyisocyanate (N-3)) Takenate D-110NB (a trimethylolpropane adduct type polyisocyanate derived from xylylene diisocyanate (hereinafter referred to as XDI), manufactured by Mitsui Chemicals) was diluted with ethyl acetate to adjust the non-volatile content to 50% and NCO% to 7.9% to obtain a polyisocyanate (N-3) solution.

[0091] (Synthesis of polyisocyanate (N-4)) Takenate D-103H (a trimethylolpropane adduct type polyisocyanate derived from tolylene diisocyanate (hereinafter referred to as TDI), manufactured by Mitsui Chemicals) was diluted with ethyl acetate to adjust the non-volatile content to 70% and NCO% to 12.0% to obtain a polyisocyanate (N-4) solution.

[0092] (Polyisocyanate (N-5)) The bifunctional compound of HDI (manufactured by Asahi Kasei, D101, 100% non-volatile content, 19.7% NCO%) is defined as polyisocyanate (N-5).

[0093] <Adhesive manufacturing> [Examples 1-20, Comparative Examples 1-7] Adhesives (S-1)-(S-27) The obtained polyester polyol, other polyols, and polyisocyanate were blended in the proportions (by mass) shown in Table 3, and ethyl acetate was added to prepare an adhesive solution (S) with a non-volatile content of 30% by mass.

[0094] <Manufacturing of laminates> The resulting adhesive was used to fabricate the laminate. For the printing ink, Rio Alpha R681 White (manufactured by Toyo Ink Co., Ltd.) was used, diluted with a mixed solvent of ethyl acetate / ilopropyl alcohol (mass ratio 70 / 30) to a viscosity of 15 seconds (25°C, Zahn Cup #3 (made by Rigo)).

[0095] A 15 μm thick NY film was printed over its entire surface using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm, and dried at 50°C to obtain a printed material (NY / printed layer). The thickness of the printed layer was adjusted to 1.5 μm. Subsequently, an adhesive was applied to the printed layer at a dry amount of 3.5 g / m². 2 To achieve this, the adhesive was applied using a dry laminating machine and dried. Then, the adhesive layer and the AL-deposited surface of the AL-deposited PET film were bonded together to obtain an intermediate laminate (NY / printed layer / adhesive layer / AL-deposited PET). The adhesive was applied to the PET surface of the obtained intermediate laminate in the same manner as above, dried, and then an LLDPE film (thickness 150 μm) was bonded to it. The laminate was stored in a 40°C atmosphere for 4 days to obtain the desired laminate (NY / printed layer / adhesive layer / AL-deposited PET / adhesive layer / LLDPE).

[0096] <Evaluation of laminates> (Evaluation of detachability) The obtained laminate was cut into 15mm x 15mm pieces to serve as test specimens. 400ml of 2% sodium hydroxide aqueous solution and 20 test specimens were placed in a 500ml flask, and the mixture was stirred for 3 hours at a set temperature of 70°C and a rotation speed of 150rpm. After stirring, the test specimens were washed and dried, and the specimens were collected to check their desegregation properties. Desegregation properties were evaluated by counting the number of test specimens in which the adhesive between the AL-deposited PET film and the LLDPE film had desegregated, separating the two types of films from each other. The ratio of these separated specimens to the 20 specimens was calculated and evaluated according to the following criteria. S (excellent): 95% or more A (Good): 85% or higher, less than 95% B (Acceptable): 80% or more, less than 85% C (Not acceptable): Less than 80%

[0097] (Initial adhesive strength) The obtained laminate was cut into 15mm x 300mm specimens to serve as test pieces. Using a tensile testing machine, T-type peeling was performed at a peeling speed of 30cm / min under conditions of 20°C and 65% relative humidity, and the adhesive strength (N / 15mm) between the AL-deposited PET and LLDPE was measured to obtain the [initial adhesive strength] result. The practical range of adhesive strength is 4N / 15mm or higher.

[0098] (Adhesive strength after testing over time) Two pieces of the resulting laminate, each measuring 10cm x 15cm, were cut out. The LLDPE layers were placed facing each other on the inside, and a pouch was created by heat sealing. The resulting pouch was filled with conditioner, sealed, and left to stand for two months in a 40°C atmosphere. Subsequently, the contents were removed, and the pouch samples, after washing and drying, were cut to a size of 15 mm x 300 mm to serve as test specimens. Similar to the initial adhesive strength, the adhesive strength (N / 15 mm) between the AL-deposited PET and LLDPE was measured, and the results for [adhesion strength over time] were obtained. The practical range for adhesive strength is 3 N / 15 mm or higher.

[0099] (Evaluation of content resistance) The content resistance was evaluated by comparing the aforementioned [initial adhesive strength] and [adhesion strength over time] and determining the strength retention rate. The retention rate was calculated using the following formula and is shown in Table 3. Retention rate (%): [Adhesive strength over time] / [Initial adhesive strength] × 100

[0100] [Table 3]

[0101] According to the evaluation results described above, the reactive adhesive of the present invention, which uses a polyol as the main component and contains a polyester polyol (A) having a quaternary carbon atom and three or more hydroxyl groups in the polyhydric alcohol, with a proportion of aliphatic alcohols having three or more hydroxyl groups being 0.1 to 2.5 moles, and whose number-average molecular weight and acid value are within a predetermined range, exhibited excellent storage stability, desorption properties, and resistance to the incorporation of contents. On the other hand, in comparative examples where the proportion of aliphatic alcohols containing quaternary carbon atoms and 3 or more hydroxyl groups in the polyhydric alcohol contained in polyester polyol (A), or the number-average molecular weight or acid value of polyester polyol (A), was outside the specified range, all results showed that one or more of the following were outside the practical range: storage stability, desorption, or content resistance.

Claims

1. A reactive adhesive for forming the detachable adhesive layer in a laminate comprising a base material and a detachable adhesive layer, wherein the base material can be separated and recovered by detaching the detachable adhesive layer, It contains a polyol main component and an isocyanate curing agent. The polyol main component includes polyester polyol (A), A reactive adhesive in which polyester polyol (A) satisfies all of the following conditions (1) to (3). (1) A reaction product or derivative thereof of a polybasic acid or its derivative and a polyhydric alcohol, wherein the polyhydric alcohol contains 0.1 to 2.5 mol% of an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups in the polyhydric alcohol. (2) The number-average molecular weight is 4,500 to 20,000. (3) The acid value is 10 mg KOH / g or more.

2. The reactive adhesive according to claim 1, wherein the polyester polyol (A) has a methylene chain having 6 or more carbon atoms derived from a polybasic acid or a derivative thereof or a polyhydric alcohol.

3. The reactive adhesive according to claim 1, wherein the polybasic acid includes an aliphatic polybasic acid having a methylene chain with 6 or more carbon atoms.

4. The reactive adhesive according to claim 1, wherein the polybasic acid contains terephthalic acid, and the content of terephthalic acid is 20 mol% or more based on the total amount of the polybasic acid or its derivatives.

5. The reactive adhesive according to claim 1, wherein the polyhydric alcohol comprises an ether-bonded aliphatic diol.

6. The reactive adhesive according to claim 1, wherein the polyester polyol (A) is a reaction product of a reaction product of a polybasic acid or a derivative thereof with a polyhydric alcohol and an acidic compound, and the mass ratio of the acidic compound to an aliphatic alcohol having a quaternary carbon atom and three or more hydroxyl groups is 60:40 to 99:

1.

7. A laminate comprising an adhesive layer between at least two substrates, wherein the adhesive layer is a cured product of a reactive adhesive according to any one of claims 1 to 6.

8. A packaging material using the laminate described in claim 7.

Images