Method for manufacturing activated energy ray-curable adhesives and laminates

Abstract

The present invention addresses the problem of providing an active energy ray-curable adhesive which is capable of exhibiting adhesion, immediately after active energy ray irradiation thereof, to a film which does not have an easily bondable layer, and also exhibiting sufficient flexibility and adhesion properties after curing.　The present invention is an active energy ray-curable adhesive which contains: a (meth)acrylate (A) which is mono- to tetra-functional and has a tertiary amino group; a polyol compound (B); and a polyisocyanate compound (C).

Description

[Technical Field]

[0001] This invention relates to an active energy ray curable adhesive and a method for manufacturing a laminate. [Background technology]

[0002] With the global population increasing, demand for flexible packaging, primarily used for food and household goods, is expected to continue to grow. In flexible packaging, it is common practice to laminate printed film materials with plastic films, metal foils, or heat-sealable films (sealants) that provide the properties required for each application, such as protecting the contents, improving impact resistance, and providing heat sealability.

[0003] Typically, film printed materials are bonded to other materials using a laminate adhesive containing polyisocyanate and polyol components, resulting in laminates and printed packaging with excellent solvent resistance even to highly polar solvents (Patent Document 1). However, such laminate adhesives contain large amounts of organic solvents such as toluene and ethyl acetate during coating, requiring a large amount of energy for solvent drying and exhaust treatment, resulting in a significant environmental burden. Furthermore, in recent years, there has been a demand to reduce the volatile components contained in adhesives in response to environmental concerns and carbon neutrality. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5657990 [Patent Document 2] Japanese Patent Application Publication No. 8-253736 [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, as described in Patent Document 2, an active energy ray-curable adhesive composition comprising an aromatic acrylic acid ester monomer and a resin has been proposed, and a laminate film is formed by irradiation with an electron beam. However, this active energy ray-curable adhesive composition has the disadvantage of being less versatile because the films it can be used with are limited to those with an easily adhesive layer.

[0006] Therefore, the present invention aims to provide an active energy ray curing adhesive that hardens instantly upon irradiation with active energy rays, exhibits adhesion immediately after irradiation with active energy rays even to films that do not have an easy-adhesion layer, and maintains sufficient adhesion even after curing. [Means for solving the problem]

[0007] The present invention relates to an active energy ray curable adhesive comprising a 1-4 functional (meth)acrylate (A) having a tertiary amino group, a polyol compound (B), and a polyisocyanate compound (C).

[0008] Furthermore, the present invention is a method for manufacturing a laminate, comprising the steps of: bonding two or more films together via the active energy ray curable adhesive of the present invention to form a laminate film; irradiating the laminate film with active energy rays; and aging the laminate, in this order. [Effects of the Invention]

[0009] The active energy ray curing adhesive according to the present invention instantly hardens upon irradiation with active energy rays, becoming tack-free. It exhibits adhesion to films without an easy-adhesion layer immediately after irradiation with active energy rays, and maintains sufficient adhesion even after curing. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. In this invention, "greater than or equal to" means the same as or greater than the numerical value shown. Also, "less than or equal to" means the same as or less than the numerical value shown. Furthermore, "(meth)acrylate" is a general term that includes acrylate and methacrylate, and "(meth)acryloyl group" is a general term that includes acryloyl group and methacryloyl group. Furthermore, "n-functional (meth)acrylate" and "(meth)acrylate is n-functional" mean that the number of (meth)acryloyl groups that the (meth)acrylate has is n.

[0011] The active energy ray curing adhesive of the present invention contains a 1-4 functional (meth)acrylate having a tertiary amino group. Hereinafter, this (meth)acrylate will also be referred to as (meth)acrylate (A).

[0012] The (meth)acrylate (A) hardens upon irradiation with active energy rays, forming a film. Furthermore, the tertiary amino group strongly interacts with polar groups such as hydroxyl groups, particularly carboxyl groups, on the film surface, thereby improving the adhesion of the cured film of the active energy ray-curable adhesive to the film immediately after irradiation with active energy rays. This adhesion improvement effect only occurs when the tertiary amino group and the (meth)acryloyl group are present in the same compound. For example, if a tertiary amine without a (meth)acryloyl group is mixed with (meth)acrylates and cured with active energy rays, the interaction between the (meth)acrylate crosslinks in the cured film and the film surface does not become strong because the two compounds are not covalently bonded, and the adhesion does not improve.

[0013] Furthermore, since the tertiary amino group contained in the (meth)acrylate (A) also acts as a catalyst in the urethane-forming reaction between the polyol compound (B) and the polyisocyanate compound (C) described below, it promotes the reaction and has the effect of shortening the curing time. Furthermore, compared with the case where a catalyst is simply coexisted, since the (meth)acrylate (A) is cured by active energy rays and incorporated into the cured film by a covalent bond, there is also an advantage that the migration property is low.

[0014] The (meth)acrylate (A) is preferably monofunctional to bifunctional. Further, when the (meth)acrylate (A) has five or more functional groups, the curing shrinkage of the active energy ray-curable adhesive is large, and the adhesion is impaired.

[0015] The (meth)acrylate (A) is preferably a compound represented by the following structural formula (1).

[0016]

Chemical formula

[0017] Here, R 1 is H or a methyl group, R 2 is a monovalent organic group having a (meth)acryloyl group, R 3 and R 4 each independently represent a monovalent hydrocarbon group or a monovalent organic group containing a heteroatom.

[0018] Further, the (meth)acrylate (A) is more preferably a compound represented by the following structural formula (2) or (3).

[0019]

Chemical formula

[0020] Here, R 1 is H or a methyl group, R 2 represents a monovalent organic group having a (meth)acryloyl group.

[0021] The (meth)acrylate (A) is preferably a compound represented by the following structural formula (4).

[0022]

Chemical formula

[0023] Here, X represents a nitrogen atom or a carbon atom, R 1 is H or a methyl group, R 2 is a monovalent organic group having a (meth)acryloyl group, R 3 and R 4 each independently represent a monovalent hydrocarbon group or a monovalent organic group containing a hetero atom. R 3 and R 4 are either independent of each other or both combine to form a cyclic group.

[0024] The amine value of the (meth)acrylate (A) preferably is 80 mgKOH / g or more in order to strongly interact with various carboxyl groups and improve adhesion. Further, in order to impart compatibility with other compounds, the amine value of the (meth)acrylate (A) is preferably 400 mgKOH / g or less, more preferably 357 mgKOH / g or less.

[0025] Here, the amine value is represented by the mg number of potassium hydroxide equivalent to hydrochloric acid required to neutralize amino groups contained in 1 g of the sample, and can be measured by a method conforming to ASTM D2074.

[0026] The (meth)acrylate (A) preferably has a hydroxyl group. By doing so, it can be added to the polyisocyanate compound (C) described later, and the curability and adhesion can be more effectively improved.

[0027] The (meth)acrylate (A) is obtained by Michael addition of a primary or secondary amine to a polyfunctional (meth)acrylate. Since the (meth)acryloyl group is an α-β unsaturated carbonyl compound, the primary or secondary amine undergoes 1,4-conjugation addition to form a 3-aminopropionate structure. If the amino group in the resulting structure is secondary, it may react again to be converted to a tertiary amine. This reaction is nucleophilic, and the higher the nucleophilicity, the milder the conditions under which it proceeds. Acids and bases can also act as catalysts, allowing the reaction to proceed at lower temperatures and faster speeds.

[0028] Specifically, when performing the Michael addition reaction, it is preferable to carry out the reaction at a temperature of 20 to 100°C or lower. Furthermore, in the reaction of polyfunctional (meth)acrylate with amines, if all (meth)acryloyl groups in one molecule react with the amine, the reaction will not harden due to the active energy rays; therefore, it is preferable that the equivalent ratio has an excess of (meth)acryloyl groups compared to amino groups. On the other hand, in order to increase the amine equivalent, it is also preferable to introduce multiple tertiary amino groups into a polyfunctional (meth)acrylate with three or more functions, preferably four or more functions. Furthermore, using polyamines with two or more functions as the starting amine is undesirable from the viewpoint of reaction control because it may crosslink with the polyfunctional (meth)acrylate and gel. In addition, it is preferable to take measures such as gradually adding the amines to the polyfunctional (meth)acrylate dropwise during synthesis, as this makes it easier to obtain the desired (meth)acrylate (A).

[0029] Furthermore, if the (meth)acrylate (A) has a hydroxyl group, either the polyfunctional (meth)acrylate used as a starting material has a hydroxyl group, or the amines to be added have a hydroxyl group, or both.

[0030] For the Michael addition reaction described above, polyfunctional (meth)acrylates are used as starting materials because the (meth)acryloyl group must remain after the reaction. Monofunctional (meth)acrylates are unsuitable because the (meth)acryloyl group is lost after Michael addition.

[0031] Specific examples of difunctional (meth)acrylates that serve as raw materials for the Michael addition reaction include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate. Examples include acrylates, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, diglycerin di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and their ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adducts, etc.

[0032] Examples of trifunctional (meth)acrylates that serve as raw materials for the Michael addition reaction include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, isocyanuric acid tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, and their ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adducts, etc.

[0033] Examples of tetrafunctional (meth)acrylates used as raw materials for the Michael addition reaction include ditrimethylolpropanetetra(meth)acrylate, diglycerintetra(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, and their ethylene oxide adducts and propylene oxide adducts.

[0034] Examples of (meth)acrylates with five or more functionalities that serve as raw materials for the Michael addition reaction include dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and their ethylene oxide adducts and propylene oxide adducts. In particular, when using (meth)acrylates with six or more functionalities, it is preferable to set the equivalent ratio such that two or more functionalities react with amines.

[0035] Specific examples of primary amines that serve as raw materials for the Michael addition reaction include, as monoamines, alkylamines having 1 to 20 carbon atoms, alkanolamines having 1 to 10 carbon atoms, and their derivatives. Specific examples of secondary amines include N-alkyl substituted derivatives (1 to 20 carbon atoms) of the monoamines, N-alkanol substituted derivatives (1 to 10 carbon atoms) of the monoamines, cyclic amines such as morpholine, pyrrolidine, and piperidine, and derivatives of these other than N-substituted derivatives, 1H-azoles such as 1H-triazole, 1H-benzotriazole, 1H-benzimidazole, 1H-imidazole, and 1H-pyrazole, and derivatives of these other than 1H substituted derivatives. These polyamines can also be used, but in that case, control is necessary to suppress gelation.

[0036] Of these primary and secondary amines, those with a low odor are preferred, and octadecylamine and diethanolamine are particularly preferred because they are usable raw materials in food packaging regulations such as the Swiss Ordinance.

[0037] Furthermore, adducts of heterocyclic 1H-azoles, such as 1H-triazole, 1H-benzotriazole, 1H-benzimidazole, and 1H-imidazole, are particularly preferred due to their significant effect in improving adhesion.

[0038] Of these primary and secondary amines, highly nucleophilic aliphatic amines undergo the Michael addition reaction under relatively mild conditions of 20-60°C. On the other hand, less nucleophilic aromatic amines react slowly, and the Michael addition reaction is preferably carried out by heating to 80-100°C.

[0039] When (meth)acrylate (A) is synthesized using the particularly preferred diethanolamines listed above, the compound represented by structural formula (2) is obtained. When (meth)acrylate (A) is synthesized using octadecylamine, the compound represented by structural formula (3) is obtained. Furthermore, when (meth)acrylate (A) is synthesized using 1H-azoles, the compound represented by structural formula (4) is obtained.

[0040] The (meth)acrylate (A) may be a commercially available product, for example, "EBECRYL" (registered trademark) LEO 10101, "EBECRYL" (registered trademark) LEO 10551, "EBECRYL" (registered trademark) LEO 10552, "EBECRYL" (registered trademark) LEO 10553, EBECRYL® 80, EBECRYL® 81, EBECRYL® 83, EBECRYL® 85, EBECRYL® 880, EBECRYL® 7100, ETERCURE® 63922 from Eternal Corporation, CN549NS, CN550, CN551NS from SARTOMER Corporation, AgiSyn® 701, AgiSyn® 701P, AgiSyn® 703, AgiSyn® 703TF from DSM Corporation, Miramer® AS1000, Miramer® AS3500, Miramer® LR3600 from Miwon Corporation, Photocryl A104, Photocryl Examples include the DP143.

[0041] The molecular weight of the (meth)acrylate (A), when it does not have a hydroxyl group, is preferably 1000 or less, from the viewpoint of improving curability to active energy rays and suppressing viscosity increase of the active energy ray-curable adhesive of the present invention. More preferably, it is 600 or less. On the other hand, when it has a hydroxyl group, the weight-average molecular weight is preferably 3000 or more and 100000 or less, from the viewpoint of improving curability and adhesion when added to the polyisocyanate compound (C).

[0042] The (meth)acrylate (A) is preferably contained in the active energy ray curable adhesive in an amount of 10% by mass or more and 40% by mass or less.

[0043] The film adhesion is improved when the content of the (meth)acrylate (A) is 10% by mass or more, more preferably 20% by mass or more.

[0044] The (meth)acrylate (A) content is 40% by mass or less, which allows for the inclusion of other functional materials depending on the application, the addition of initiators and sensitizers depending on the active energy source, and the addition of resins, oligomers, auxiliary agents, etc., to adjust the viscoelasticity of the active energy ray curable adhesive.

[0045] The active energy ray curing adhesive of the present invention contains a polyol compound (B). The polyol compound (B) refers to a compound having two or more hydroxyl groups.

[0046] Specific examples of the polyol compound (B) include neopentyl glycol, 1,3-butanediol, 1,4-butanediol, tripropylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, pentaerythritol, ditrimethylolpropane, diglycerin, dipentaerythritol, ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adducts, lactone adducts, and the like.

[0047] Furthermore, it is preferable that the polyol compound (B) is a polyester polyol, as this improves the heat resistance of the active energy ray curing adhesive and provides resistance to boiling and retorting.

[0048] The polyester structure in the aforementioned polyester polyol is obtained by reacting a dicarboxylic acid derivative with a diol. Specific examples of the dicarboxylic acid derivative include phthalic acid, isophthalic acid, terephthalic acid, adipic acid, oxalic acid, maleic acid, fumaric acid, and sebacic acid. These can be reacted with diols to form a polyester structure, and a polyester polyol with hydroxyl groups at the ends can be used.

[0049] In addition, polyol compounds having a carbonate structure can also be used. Specifically, examples include pentamethylene carbonate diol, hexamethylene carbonate diol, hexane carbonate diol, and decane carbonate diol. Furthermore, these polyol compounds can be used individually or in combination of two or more.

[0050] The molecular weight of the polyol compound (B) is preferably 500 or more, more preferably 1000 or more, and even more preferably 2000 or more, from the viewpoint of improving adhesion by increasing molecular weight. On the other hand, the molecular weight of the polyol compound (B) is preferably 10,000 or less, more preferably 7,000 or less, and even more preferably 5,000 or less, from the viewpoint of increasing the fluidity of the adhesive and improving its applicability.

[0051] The active energy ray-curable adhesive of the present invention contains a polyisocyanate compound (C). The polyisocyanate compound (C) refers to a compound having two or more isocyanate groups and is a component that becomes high molecular weight through an addition reaction. In the active energy ray-curable adhesive of the present invention, polyurethane is formed by mixing the polyol compound (B) and the polyisocyanate compound (C) in a reaction.

[0052] In particular, in the polyurethane formation reaction, the tertiary amino group contained in (meth)acrylate (A) also acts as a catalyst, thus promoting the reaction and shortening the curing time. Furthermore, compared to simply having a catalyst in the presence of other materials, the (meth)acrylate (A) is cured by active energy rays and incorporated into the cured film by covalent bonds, which has the advantage of low migration properties.

[0053] Specific examples of the polyisocyanate compound (C) include toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4-methylenebiscyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and trimethylhexamethylene diisocyanate. Nurate-modified, adduct-modified, biuret-modified, and allophanate-modified forms of these polyisocyanate compounds can also be used. One or more of these diisocyanates can be used in combination.

[0054] The weight-average molecular weight of the polyisocyanate compound (C) is preferably 500 or more, more preferably 1000 or more, and even more preferably 2000 or more, from the viewpoint of suppressing elution if it remains in the cured product of the adhesive. On the other hand, the weight-average molecular weight of the polyisocyanate compound (C) is preferably 10000 or less, more preferably 7000 or less, and even more preferably 5000 or less, from the viewpoint of increasing the fluidity of the adhesive and improving its applicability.

[0055] The total content of the polyol compound (B) and the polyisocyanate compound (C) in the active energy ray-curable adhesive of the present invention is preferably 50% by mass or more, and more preferably 60% by mass or more, from the viewpoint of improving the adhesion of the final laminate film and further making the cured product of the active energy ray-curable adhesive flexible. Furthermore, to reduce curability to active energy rays and viscosity of the adhesive, it is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0056] Furthermore, regarding the equivalent ratio of the polyol compound (B) to the polyisocyanate compound (C), it is preferable that the content of isocyanate groups in the polyisocyanate compound is 0.8 mol or more and 1.2 mol or less per 1.0 mol of hydroxyl groups in the polyol compound (B).

[0057] Furthermore, if the (meth)acrylate (A) has hydroxyl groups, it is preferable that the content of isocyanate groups of the polyisocyanate compound is 0.8 mol or more and 1.2 mol or less per 1.0 mol of the total amount of hydroxyl groups of the (meth)acrylate (A) and the polyol compound (B). The closer the equivalent ratio, the more the chain extension reaction proceeds, leading to a higher molecular weight polyurethane and improved adhesion.

[0058] The active energy ray curable adhesive of the present invention preferably includes a polyfunctional (meth)acrylate having a weight-average molecular weight of less than 3000 and not containing an amino group. Hereinafter, this (meth)acrylate will also be referred to as (meth)acrylate(D). The (meth)acrylate(D) hardens upon irradiation with active energy rays and contributes to film formation.

[0059] The (meth)acrylate (D) is preferably highly reactive from the viewpoint of curability. Furthermore, from the viewpoint of safety and the environment, it is preferably low in volatility. Low volatility means that the weight loss rate when heated at 110°C for 1 hour is 1% by weight or less, as defined by Method 24 of the U.S. Environmental Protection Agency (EPA).

[0060] Specific examples of such (meth)acrylates (D) include, for example, difunctional (meth)acrylates (D) such as 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate. Examples include chol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, diglycerin di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and their ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adducts, etc.

[0061] Examples of trifunctional (meth)acrylates (D) include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, isocyanuric acid tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, and their ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adducts, etc.

[0062] Examples of tetrafunctional (meth)acrylates (D) include ditrimethylolpropanetetra(meth)acrylate, diglycerintetra(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, and their ethylene oxide adducts and propylene oxide adducts.

[0063] Examples of (meth)acrylates (D) with five or more functionalities include dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and their ethylene oxide adducts and propylene oxide adducts.

[0064] The active energy ray-curable adhesive of the present invention preferably contains a compound having a carboxyl group with a weight-average molecular weight of 3,000 to 100,000. Hereinafter, this compound will also be referred to as compound (E). The tertiary amino group of (meth)acrylate (A) and the carboxyl group of compound (E), which has a high molecular weight, interact to improve the film-forming properties and film strength of the cured film of the active energy ray-curable adhesive.

[0065] In the active energy ray curable adhesive of the present invention, the number of moles of carboxyl groups derived from compound (E) is n c The number of moles n of amino groups derived from (E) and (A) a (A) Ratio n c (E) / n a (A) is preferably 0.01 or more and 0.50 or less. c (E) / n a When (A) is 0.01 or higher, it is possible to effectively improve the film formation properties and film strength of the cured film of the active energy ray curing adhesive. Also, n c (E) / n a When (A) is 0.50 or less, more preferably 0.30 or less, and even more preferably 0.15 or less, an improvement in adhesion due to the interaction between the tertiary amino group and the polar group on the film surface can be effectively obtained.

[0066] The compound (E) preferably has a (meth)acryloyl group and / or a vinyl group. Since the compound (E) also interacts with the (meth)acrylate (A) to crosslink, the presence of such photosensitive groups in the compound (E) improves its curability to active energy rays, thereby improving the strength and adhesion of the cured film.

[0067] The active energy ray curable adhesive of the present invention may contain a photopolymerization initiator depending on the active energy ray source. Examples of photopolymerization initiators include α-aminoalkylphenones, thioxanthones, benzyl ketals, and acylphosphine oxides.

[0068] Furthermore, the active energy ray curing adhesive of the present invention can also use additives such as waxes, pigment dispersants, defoamers, and leveling agents as other components.

[0069] The active energy ray-curable adhesive of the present invention preferably contains substantially no solvents and diluents. Here, "solvent" refers to a substance that does not contain (meth)acryloyl groups and is liquid at 1 atmosphere and 25°C. Furthermore, "substantially free of solvents and diluents" means that the total content of solvents and diluents in the active energy ray-curable adhesive is 0.1% by mass or less. By substantially containing no solvents, the curability of the adhesive against active energy rays can be improved. Additionally, the transfer of solvents through the printed film to the contents can be suppressed.

[0070] The acrylic equivalent of the active energy ray-curable adhesive of the present invention is preferably 300 g / eq or more and 1000 g / eq or less. A acrylic equivalent of 300 g / eq or more, more preferably 500 g / eq or more, improves storage stability. Furthermore, a acrylic equivalent of 1000 g / eq or less, more preferably 800 g / eq or less, results in good curability by active energy rays. In this invention, acrylic equivalent refers to the number of grams (unit: g / eq) of the active energy ray-curable adhesive required to contain 1 mole of (meth)acryloyl groups.

[0071] Next, a method for producing the active energy ray curing adhesive of the present invention will be described.

[0072] The active energy ray curing adhesive of the present invention can be obtained by mixing the (meth)acrylate (A), the polyol compound (B), the polyisocyanate compound (C), and optionally the (meth)acrylate (D), the compound (E), and other components at room temperature to 80°C.

[0073] Degassing under vacuum or reduced pressure conditions is also preferably performed after mixing or during the mixing process.

[0074] Furthermore, when the polyol compound (B) and the polyisocyanate compound (C) are mixed, a polyurethane formation reaction proceeds and the mixture begins to thicken. Therefore, it is practically preferable to prepare an α-liquid of the polyisocyanate compound (C) and a β-liquid mixed with other components, mix the two liquids immediately before use, and use them as an adhesive in a laminator.

[0075] A first aspect of the method for manufacturing a laminate of the present invention includes, in this order, a laminating step of bonding the same or two or more films to each other via the active energy ray curable adhesive of the present invention to form a laminate film, an irradiation step of irradiating the laminate film with active energy rays, and an aging step of aging.

[0076] In the lamination process described above, the active energy ray-curable adhesive of the present invention is applied to one of the films, and the other film is bonded to the wet coating to obtain a laminated film. A printed material with ink printed on it is suitable as one of the films, and a sealant is suitable as the other film.

[0077] Furthermore, a second aspect of the method for manufacturing a laminate of the present invention includes, in this order, a step of applying an active energy ray-curable adhesive to a film, an irradiation step of irradiating the film coated with the adhesive with active energy rays, a laminating step of bonding the same or different type of film to the film coated with the adhesive to form a laminate film, and an aging step of aging. Irradiating the film coated with the adhesive with active energy rays is preferable because it does not involve the other film to be bonded, thus improving curability and, depending on the energy source, not damaging the other film.

[0078] Examples of films used in the present invention include polyesters such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polylactic acid, as well as polyamides, polyimides, polyalkyl (meth)acrylates, polystyrene, poly-α-methylstyrene, polycarbonate, polyvinyl alcohol, polyvinyl acetal, polyvinyl chloride, and polyvinylidene fluoride.

[0079] Furthermore, films that have a vapor-deposited thin film layer made of a metal or metal compound such as alumina are also used.

[0080] The surface of the film is preferably corona-treated, as this increases the number of polar functional groups on the film surface and improves adhesion with active energy ray-curable adhesives. Furthermore, if the film is a printed material, it is preferable that the surface of the plain portion of the film is corona-treated.

[0081] The surface-treated film can be a commercially available product, or it can be a film that has undergone inline corona treatment before printing or lamination.

[0082] The aforementioned film may have an easy-adhesion coating layer, but this increases the cost. The active energy ray curing adhesive of the present invention is suitable because it can exhibit sufficient adhesion even to films that do not have an easy-adhesion layer.

[0083] The aforementioned film can be in the form of either a sheet or a roll. When using a thin film for flexible packaging, it is preferable to use a roll film and coat and print it using a roll-to-roll method.

[0084] In the irradiation process described above, the (meth)acryloyl groups react with the irradiation of active energy rays and crosslink by covalent bonds, thereby instantly curing the active energy ray-curable adhesive.

[0085] Examples of active energy sources used in the irradiation process include ultraviolet rays, electron beams, and gamma rays.

[0086] For ultraviolet light, UV irradiation devices such as high-pressure mercury lamps, xenon lamps, metal halide lamps, and light-emitting diodes (LEDs) are preferably used. Among these, LED lamps are preferred because they are energy-efficient and produce less ozone. For LEDs, a wavelength of 350 to 420 nm is preferred from the standpoint of energy saving and cost reduction.

[0087] With electron beams, (meth)acryloyl groups are directly radically excited, and radical polymerization proceeds in the active energy ray curable adhesive, forming a film. Furthermore, electron beams have high permeability and can also act on films. When the film is made of polyolefins, radicals are easily generated, causing reactions such as intermolecular crosslinking and decomposition, and radical polymerization proceeds between the active energy ray curable adhesive and the film, forming covalent bonds between the adhesive and the film, resulting in higher adhesion. In particular, electron beams with low acceleration voltage are preferred because they do not require special qualifications for use and are easy to handle. Since the penetration depth of the electron beam is determined by the acceleration voltage, the acceleration voltage is preferably 50kV to 300kV from the viewpoint of sufficient permeability and damage to the film. In addition, the irradiation dose of the electron beam is preferably 10kGy to 100kGy, as this increases the amount of radical species generated in the target material while also increasing damage to the film.

[0088] In the aging process, by heating the adhesive in an environment ranging from 40°C to 60°C, the reaction between the polyol compound (B) and the polyisocyanate compound (C) in the adhesive proceeds, increasing the molecular weight and thereby further improving adhesion. [Examples]

[0089] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples.

[0090] [Measurement and Evaluation Methods] (1) Amine value The amine value was measured according to the method compliant with ASTM D2074. Ethanol solutions of each (meth)acrylate (A) were prepared, and potentiometric titrations were performed using a potentiometric titrator with a 0.2 N hydrochloric acid-ethanol solution. The inflection point of the resulting titration curve was defined as the endpoint. The amount of hydrochloric acid consumed up to the inflection point was then converted to the equivalent amount of potassium hydroxide.

[0091] (2) Acrylic equivalent Prepare a 1% by mass solution of each active energy ray-curable adhesive using deuterated acetone, add 0.05% by mass of tetramethylsilane as an internal standard, and seal the solution. 1 ¹H-NMR measurements were performed. The molar ratio was determined from the integral ratio of the peak of the (meth)acrylic group (δ: 5.8~6.5) and the peak of the methyl group of the internal standard tetramethylsilane (δ: -0.05~+0.05), and the number of moles of acrylic groups in the adhesive was calculated, and the acrylic equivalent was determined.

[0092] (3) Weight average molecular weight The weight-average molecular weight was measured by gel permeation chromatography (GPC) with tetrahydrofuran as the mobile phase at a column temperature of 40°C. A Shodex KF-803 column was used, and the weight-average molecular weight was calculated using polystyrene equivalents.

[0093] (4) Appearance of the coating The appearance of the coated materials of the active energy ray curing adhesives obtained in each example and comparative example was evaluated visually as follows. A: No air bubbles are visible, and the appearance is good. B: Very small bubbles were observed. C: Air bubbles or a peel-like texture were observed throughout.

[0094] (5) Peel strength The samples obtained in each example and comparative example were cut into strips 15 mm wide, and the peel strength was measured using a Tensilon universal testing machine (RTG-1210, manufactured by Orientec Co., Ltd.) when peeled at 90° at 300 mm / min.

[0095] The peel strength of the sample immediately after curing with active energy rays was evaluated as "initial adhesion." Furthermore, the peel strength of the sample after aging at 40°C for 72 hours (after curing) was evaluated as "adhesion after curing."

[0096] Regarding initial adhesion, a peel strength of less than 1.0 N / 15 mm was judged to indicate insufficient adhesion, 1.0 N / 15 mm or more and less than 2.0 N / 15 mm was judged to indicate good adhesion, and 2.0 N / 15 mm or more was judged to indicate extremely good adhesion.

[0097] Furthermore, regarding adhesion after curing, a peel strength of less than 3.0 N / 15 mm was judged to indicate insufficient adhesion, 3.0 N / 15 mm or more and less than 4.0 N / 15 mm to indicate good adhesion, and 4.0 N / 15 mm or more to indicate extremely good adhesion.

[0098] (6) Destruction Mode In the peel test after curing described in (5) above, the behavior during peeling (failure mode) was also observed. In the multilayered sample, the area where failure occurred during peeling corresponds to the point where the adhesion between layers was weakest. This was evaluated using the following A to C criteria. A: The film broke. B: The active energy ray curing adhesive layer underwent cohesive failure. C: Delamination occurred between the film and the active energy ray curable adhesive layers. Here, "active energy ray curable adhesive layer" refers to a layer formed by curing an active energy ray curable adhesive. The above A is the most preferred, the above B is the next preferred, and the above C is unpreferred.

[0099] [(Meth)acrylate (A)] In the following procedure, the corresponding primary or secondary amine and polyfunctional (meth)acrylate were weighed and mixed and stirred in a mechanical stirrer at 60°C for 4 hours to carry out the Michael addition reaction and obtain the corresponding (meth)acrylate (A). (A)-1: A bifunctional (meth)acrylate obtained by Michael addition reaction of pentaerythritol triacrylate (MIWON "Miramer" (registered trademark) M340) with diethanolamine (Wakken Pharmaceutical Co., Ltd.) in an equivalent ratio of 5:2. Contains a hydroxyl group. Amine value 159 mgKOH / g. Weight-average molecular weight 360. (A)-2: A 2- or 3-functional (meth)acrylate obtained by Michael addition reaction of di(2-ethylhexyl)amine (manufactured by Wakken Pharmaceutical Co., Ltd.) in an equivalent ratio of 2:1 to ditrimethylolpropanetetraacrylate (Miramer® M410, manufactured by MIWON). No hydroxyl groups. Amine value 118 mgKOH / g. Weight-average molecular weight 590. (A)-3: A bifunctional (meth)acrylate obtained by Michael addition reaction of EO-modified trimethylolpropane triacrylate (MIWON "Miramer" (registered trademark) M3190) with di(2-ethylhexyl)amine (Wakken Pharmaceutical Co., Ltd.) in an equivalent ratio of 2:1. No hydroxyl group. Amine value 79 mgKOH / g. Weight-average molecular weight 810. (A)-4: A 1-2 functional (meth)acrylate obtained by Michael addition reaction of tricyclodecanedimethanol diacrylate (Daicel Ornex "EBECRYL" (registered trademark) 130) with octadecylamine (TCI Co., Ltd.) in an equivalent ratio of 2:1. No hydroxyl group. Amine value 96 mgKOH / g. Weight-average molecular weight 420. (A)-5: Dimethylaminoethyl methacrylate (manufactured by TCI Corporation). (A)-5 is a monofunctional (meth)acrylate. Hydroxyl group absent. Amine value 357 mgKOH / g. Weight-average molecular weight 160. (A)-6: A 4-5 functional (meth)acrylate obtained by Michael addition reaction of dipentaerythritol hexaacrylate (MIWON "Miramer" (registered trademark) M600) with 1H-benzotriazole (Wakken Pharmaceutical Co., Ltd.) in an equivalent ratio of 3:1. No hydroxyl groups. Amine value 135 mgKOH / g. Weight-average molecular weight 630. (A)-7: A 1-3 functional (meth)acrylate obtained by Michael addition reaction of pentaerythritol triacrylate (MIWON "Miramer" (registered trademark) M340) and dimethylaminoethyl methacrylate (TCI Co., Ltd.) with polyetheramine (HUNTSMAN "JEFFAMINE" (registered trademark) D-2000) in an equivalent ratio of 1:3:1. Contains hydroxyl groups. Amine value 91 mgKOH / g. Weight-average molecular weight 3200.

[0100] [Polyol compound (B)] (B)-1: Mitsui Chemicals' "Takelac" (registered trademark) A-244B (B)-2: Mitsui Chemicals' "Takelac" (registered trademark) A-246B.

[0101] [Polyisocyanate compound (C)] (C)-1: Mitsui Chemicals "Takenate" (registered trademark) A-244A (C)-2: Mitsui Chemicals' "Takenate" (registered trademark) A-246A.

[0102] [(Meth)acrylate (D)] (D)-1: EO-modified trimethylolpropane triacrylate (MIWON "Miramer" (registered trademark) M3190) (D)-2: Ditrimethylolpropanetetraacrylate (Made by MIWON Corporation “Miramer” (registered trademark) M410).

[0103] [Compound (E)] (E)-1: Acrylic resin having photosensitive groups and carboxylic acid (TWR-1001, manufactured by Toray Industries, Inc.). Molecular weight 30000, acid value 105 mgKOH / g. (E)-2: Acrylic resin containing carboxylic acid (TWR-3001, manufactured by Toray Industries, Inc.). Molecular weight 27000, acid value 200 mgKOH / g.

[0104] [Other (meth)acrylates] (F)-1: A trifunctional (meth)acrylate having a tertiary amino group, obtained by Michael addition reaction of di(2-ethylhexyl)amine (manufactured by Wakken Pharmaceutical Co., Ltd.) with dipentaerythritol hexaacrylate (Miramer® M600, manufactured by MIWON) in an equivalent ratio of 6:1. Amine value: 66 mgKOH / g.

[0105] [Other additives] Photopolymerization initiator: Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BASF "Irgacure" (registered trademark) 819) Solvent: Ethyl acetate (manufactured by Wakken Pharmaceutical Co., Ltd.).

[0106] [Activated energy ray curing adhesive] Each material was weighed according to the composition shown in Table 1, and an active energy ray curing adhesive was obtained by mixing and dissolving them using a hybrid mixer (manufactured by Thinky Co., Ltd.).

[0107] [Table 1]

[0108] [film] Film 1: 12μm thick PET film (E5102 manufactured by Toyobo Co., Ltd.), with a corona-treated layer. Film 2: 12μm thick PET film (FS2000 manufactured by Futamura Chemical Co., Ltd.), no surface treatment. Film 3: 15 μm thick polyamide film (ON, manufactured by Unitika Ltd.), with a corona-treated layer. Film 4: A barrier film / PET film laminate with a thickness of 12 μm (1011HG SBR2 manufactured by Toray Film Processing Co., Ltd.), without a corona treatment layer. Film 5: 20μm thick OPP film (Toyobo Co., Ltd. P2111), with a corona-treated layer. Film 6: 12μm thick PET film (Toray Industries, Inc. "Lumirror" (registered trademark) S10), no surface treatment.

[0109] [Method for manufacturing a laminate 1] Various types of active energy ray curing adhesives are applied to various films at a rate of approximately 2.0 g / m². 2 After coating the surface, a sealant (unoriented polypropylene film (CPP) (ZK-207, manufactured by Toray Film Processing Co., Ltd., 60 μm thick) was laminated onto it. Then, the adhesive was cured by irradiating the substrate film side with an electron beam (EC250 / 30 / 90LS, manufactured by Iwasaki Electric Co., Ltd.) at an acceleration voltage of 110 kV and an irradiation dose of 30 kGy. After that, it was cured at 40°C for 72 hours.

[0110] [Method for manufacturing a laminate 2] Various types of active energy ray curing adhesives are applied to various films at a rate of approximately 2.0 g / m². 2 After coating to achieve the desired result, a sealant (unoriented polypropylene film (CPP) (ZK-207, manufactured by Toray Film Processing Co., Ltd., 60 μm thick) was laminated onto the surface. Then, an ultraviolet light-emitting diode (LED) irradiation device (UD90, manufactured by Panasonic Devices SUNX Co., Ltd.) was used to irradiate the surface at an intensity of 8 W / cm². 2 The adhesive was cured by irradiating the substrate film with LED-UV light at a wavelength of 385 nm. Afterward, it was cured at 40°C for 72 hours.

[0111] [Method for manufacturing a laminate 3] For various types of films, a corona treatment device (TEC-4AX, manufactured by Kasuga Electric Co., Ltd.) was used, with a discharge rate E of 200 W·min / m². 2 Corona treatment was performed under these conditions. Subsequently, various active energy ray curing adhesives were applied at a rate of approximately 2.0 g / m². 2The surface was coated to achieve the desired appearance, and then laminated with a sealant (unoriented polypropylene film (CPP) (ZK-207, manufactured by Toray Film Processing Co., Ltd., 60 μm thick)). The adhesive was then cured by electron beam irradiation from the base film side using an electron beam irradiation device (EC250 / 30 / 90LS, manufactured by Iwasaki Electric Co., Ltd.) with an acceleration voltage of 110 kV and an irradiation dose of 30 kGy. After that, it was cured at 40°C for 72 hours.

[0112] [Method for manufacturing a laminate 4] Various types of active energy ray curing adhesives are applied to various films at a rate of approximately 2.0 g / m². 2 After coating the surface, the adhesive was cured by irradiating it with an electron beam (EC250 / 30 / 90LS manufactured by Iwasaki Electric Co., Ltd.) from the adhesive side using an acceleration voltage of 110kV and an irradiation dose of 30kGy. Then, a sealant (unoriented polypropylene film (CPP), ZK-207 manufactured by Toray Film Processing Co., Ltd., 60μm thick) was laminated onto the surface. After that, it was cured at 40°C for 72 hours.

[0113] [Example 1] A laminate was fabricated using active energy ray curable adhesive 1 as the active energy ray curable adhesive and film 1 as the film, according to the laminate manufacturing method 1. The peel strength was good, with initial adhesion of 1.8 N / 15 mm and extremely good adhesion after curing of 4.5 N / 15 mm. The failure mode was also good (A), and the appearance of the coated object was good. The results are shown in Table 2.

[0114] [Examples 2-15 and Comparative Examples 1-3] Laminates were prepared using Active Energy Ray Curable Adhesives 2-15, 17-19 as the Active Energy Ray Curable Adhesive and Film 1 as the Film, according to Laminate Manufacturing Method 1. In Examples 2-15, the peel strength was good or better in all cases. An increase in the (meth)acrylate (A) component tended to improve initial adhesion, but a decrease in the amount of polyol compound (B) and polyisocyanate compound (C) components tended to decrease the adhesion after curing. In Comparative Examples 1-3, the absence of the (meth)acrylate (A) component resulted in insufficient initial adhesion, and the absence of the polyol compound (B) and polyisocyanate compound (C) components resulted in insufficient adhesion after curing. The results are shown in Table 2.

[0115] [Examples 16-20] Laminates were fabricated using Active Energy Ray Curable Adhesive 1 as the Active Energy Ray Curable Adhesive and Films 2-6 as the Films, according to Laminate Manufacturing Method 1. The peel strength was good or better for both initial adhesion and post-curing adhesion, and the results were particularly excellent for corona-treated films. The results are shown in Table 3.

[0116] [Examples 21 and 22] Laminates were fabricated by UV curing using the laminate manufacturing method 2, with active energy ray curable adhesive 16 as the active energy ray curable adhesive and films 1 and 2 as the films. For both films, the peel strength was good or better for both initial adhesion and post-curing adhesion, and was particularly excellent for corona-treated film 1. The results are shown in Table 3.

[0117] [Examples 23 and 24] A laminate was fabricated using active energy ray curable adhesive 1 as the active energy ray curable adhesive and films 2 and 4 as the films, according to the laminate manufacturing method 3. Corona treatment improved both the initial adhesion and the adhesion after curing for both films, and the laminate peel strength was extremely good. The results are shown in Table 3.

[0118] [Example 25] A laminate was fabricated using an active energy ray-curable adhesive 1 and a film 4, according to a laminate manufacturing method 4. Electron beam irradiation before lamination accelerated curing and improved initial adhesion. The final laminate peel strength was comparable to that of Example 18, indicating a favorable result. The results are shown in Table 3.

[0119] The laminates of Examples 1 to 25 did not develop cracks or fissures in the active energy ray-curable adhesive layer when bent, and active energy ray-curable adhesives 1 to 16 possessed flexibility as cured films. On the other hand, when the laminate of Comparative Example 2 was bent, cracks and fissures occurred in the active energy ray-curable adhesive layer, and active energy ray-curable adhesive 18 did not possess flexibility as a cured film.

[0120] [Table 2]

[0121] [Table 3]

Claims

1. An active energy ray curable adhesive comprising a 1-4 functional (meth)acrylate (A) having a tertiary amino group, a polyol compound (B), and a polyisocyanate compound (C).

2. The active energy ray curable adhesive according to claim 1, wherein the (meth)acrylate (A) is represented by structural formula (1). 【Chemistry 1】 Here, R １ is H or methyl group, R ２ R is a monovalent organic group having a (meth)acryloyl group. ３ and R ４ Each of these independently represents a monovalent hydrocarbon group or a monovalent organic group containing a heteroatom.

3. The active energy ray curable adhesive according to claim 1 or 2, wherein the amine value of the (meth)acrylate (A) is 80 mg KOH / g or more.

4. The active energy ray curable adhesive according to claim 1 or 2, wherein the acrylic equivalent of the active energy ray curable adhesive is 300 g / eq or more and 1000 g / eq or less.

5. The active energy ray curable adhesive according to claim 1 or 2, wherein the (meth)acrylate (A) is contained in the active energy ray curable adhesive in an amount of 10% by mass or more and 40% by mass or less.

6. The active energy ray curable adhesive according to claim 1 or 2, wherein the (meth)acrylate (A) has a hydroxyl group.

7. The active energy ray curable adhesive according to claim 1 or 2, wherein the (meth)acrylate (A) is represented by structural formula (2) or (3). 【Chemistry 2】 Here, R １ is H or methyl group, R ２ represents a monovalent organic group having a (meth)acryloyl group.

8. The active energy ray curable adhesive according to claim 1 or 2, wherein the (meth)acrylate (A) is represented by structural formula (4). 【Transformation 3】 Here, X represents a nitrogen atom or a carbon atom, and R １ represents H or a methyl group, R ２ represents a monovalent organic group having a (meth)acryloyl group, R ３ and R ４ each independently represents a monovalent hydrocarbon group or a monovalent organic group containing a heteroatom. R ３ and R ４ are independent of each other or both are combined to form a cyclic group.

9. The active energy ray curable adhesive according to claim 6, wherein the weight-average molecular weight of the (meth)acrylate (A) is 3,000 or more and 100,000 or less.

10. An active energy ray curable adhesive according to claim 1 or 2, comprising a polyfunctional (meth)acrylate (D) having a weight-average molecular weight of less than 3000 and not containing an amino group.

11. The active energy ray curing adhesive according to claim 1 or 2, wherein the total content of the polyol compound (B) and the polyisocyanate compound (C) is 50% by mass or more.

12. The compound (E) comprises a compound having carboxyl groups with a weight-average molecular weight of 3,000 to 100,000, and the number of moles of carboxyl groups derived from the compound (E) is n. ｃ (E) and the number of moles n of amino groups derived from the (meth)acrylate (A) ａ (A) Ratio n ｃ (E) / n ａ The active energy ray curing adhesive according to claim 1 or 2, wherein (A) is 0.01 or more and 0.50 or less.

13. The active energy ray curable adhesive according to claim 1 or 2, wherein the compound (E) has a (meth)acryloyl group and / or a vinyl group.

14. An active energy ray curable adhesive according to claim 1 or 2, substantially free of solvents and diluents.

15. A method for manufacturing a laminate, comprising, in this order: a laminating step of bonding one or more films of the same type to each other via an active energy ray curing adhesive as described in claim 1 to form a laminate film; an irradiation step of irradiating the laminate film with active energy rays; and an aging step of aging the laminate.

16. A method for manufacturing a laminate, comprising the steps of: applying an active energy ray-curable adhesive according to claim 1 to a film; irradiating the film coated with the adhesive with active energy rays; laminating the film coated with the adhesive by bonding the same or different types of films to each other to form a laminate film; and aging the film.

17. The method for manufacturing a laminate according to claim 15 or 16, wherein the surface of the film is corona treated.

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