JP2023160272A - Active energy ray-curable adhesive and method for producing laminate using the same - Google Patents

Abstract

To provide an active energy ray-curable adhesive that is superior in applicability to a film substrate and adhesiveness to a film substrate after heat water treatment.SOLUTION: An active energy ray-curable adhesive includes a resin with an ethylenically unsaturated group and a hydrophilic group (A), an ethylenic unsaturated compound (B), a polyvalent isocyanate compound (C) and a polyvalent alcohol compound (D). The active energy ray-curable adhesive has a light transmittance of 80% or more for wavelengths from 250 to 450 nm.SELECTED DRAWING: None

Description

The present invention relates to an active energy ray-curable adhesive and a method for producing a laminate using the same.

The packaging printing market continues to grow as the global population increases. In particular, flexible packaging printing using thin film as a base material is widely used for various applications such as daily necessities, foodstuffs, and pharmaceuticals. In flexible packaging printing, plastic films, metal foils, and It is common to attach heat-melting films (sealants), etc., and there is an increasing need for laminate adhesive technology for flexible packaging that bonds dissimilar materials.

A film with a phase-separated structure in which cyclic olefin resin is dispersed in layers in propylene resin and active energy ray-curable printing are used as packaging printed materials that suppress the elution of printing ink and adhesive components into the contents. A packaging printed material having a printing layer made of ink has been proposed (see, for example, Patent Document 1). In addition, an active energy ray-curable varnish composition containing a binder resin, a polymerizable monomer, a wax, and a phosphoric acid compound is applied onto a base material, a polyolefin film is attached, and the coating is applied by irradiation with active energy rays. A laminate has been proposed that is obtained by curing a layer to form a cured layer and peeling the polyolefin film from the cured layer (for example, see Patent Document 2). However, when such packaging printed materials and laminates are subjected to retort treatment or used for long periods of time under high temperature and high humidity conditions, there is a problem in that the adhesion deteriorates.

On the other hand, an active energy ray-curable adhesive containing an unsaturated compound (A) having one ethylenically unsaturated group and a urethane (meth)acrylate compound (B) is useful as an adhesive component for optical films. A adhesive composition has been disclosed (for example, see Patent Document 3).

JP2016-94217A JP 2021-147494 Publication Japanese Patent Application Publication No. 2017-210607

However, the active energy ray-curable adhesive composition described in Patent Document 3 has a high viscosity and has a problem in applicability to a film base material.

Therefore, an object of the present invention is to provide an active energy ray-curable adhesive that has excellent applicability to film substrates and excellent adhesion to film substrates after hot water treatment.

In order to solve the above problems, the present invention mainly has the following configuration.
(1) Contains a resin having an ethylenically unsaturated group and a hydrophilic group (A), an ethylenically unsaturated compound (B), a polyvalent isocyanate compound (C) and a polyhydric alcohol compound (D), with a wavelength of 250~ An active energy ray-curable adhesive having a light transmittance of 80% or more at 450 nm.
(2) The active energy ray-curable adhesive according to (1), which has a carboxyl group and a hydroxyl group as the hydrophilic group of the resin (A).
(3) The active energy ray-curable adhesive according to (1) or (2), wherein the resin (A) has an acid value of 30 mgKOH/g or more and 250 mgKOH/g or less.
(4) The active energy ray-curable adhesive according to any one of (1) to (3), wherein the resin (A) has a glass transition temperature Tg of 60° C. or more and 150° C. or less.
(5) The active energy according to any one of (1) to (4), wherein the total content of the polyvalent isocyanate compound (C) and the polyhydric alcohol compound (D) is 50% by mass or more and 90% by mass or less. Line curing adhesive.
(6) A method for producing a laminate in which a first base material, at least a portion of which is coated with an active energy ray-curable ink, and a second base material are laminated with an adhesive layer interposed therebetween,
Step (1): Applying active energy ray-curable ink to at least a portion of the first substrate Step (3): At least one side of the first substrate coated with at least a portion of active energy ray-curable ink Step (4) of forming an adhesive layer by applying the active energy ray-curable adhesive according to any one of (1) to (5) to the first base material on which the adhesive layer is formed. Laminating the second base material Step (5): A method for manufacturing a laminate, which includes the steps of irradiating the laminate of the first base material and the second base material with active energy rays in this order.
(7) The method for producing a laminate according to (6), in which step (1), step (3), step (4), and step (5) are carried out in-line in this order.

The active energy ray-curable adhesive of the present invention has excellent applicability to film substrates and excellent adhesion to film substrates after hot water treatment.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and can be implemented with various changes depending on the purpose and use.

The active energy ray-curable adhesive (hereinafter sometimes abbreviated as "adhesive") of the present invention is a resin (A) having an ethylenically unsaturated group and a hydrophilic group (hereinafter referred to as "resin (A)"). ), an ethylenically unsaturated compound (B), a polyvalent isocyanate compound (C), and a polyhydric alcohol compound (D). By containing the resin (A) and the ethylenically unsaturated compound (B), radicals are generated by irradiation with active energy rays, and new radicals are generated by the reaction between the radicals and the ethylenically unsaturated group. Crosslinking progresses through such a chain reaction, and the adhesive hardens. At this time, since radicals are also generated from the film base material due to the active energy rays, covalent bonds are also formed between the cured adhesive and the film base material, so even if hot water treatment is performed after curing, the film base material High adhesion can be achieved. In addition, the hydrophilic group of the resin (A) improves the adhesion with the film substrate after curing due to intermolecular force interaction with the film substrate and improves wettability, and the adhesiveness with the film substrate after heat treatment is improved. Adhesion can also be improved. Furthermore, by containing the polyhydric alcohol compound (D) together with the highly polar and reactive polyvalent isocyanate compound (C), the polyhydric isocyanate compound (C) and the polyhydric alcohol compound (D) can be separated by heat treatment etc. Reacts to produce polyurethane. Generally, adhesives containing polyurethane have high viscosity, whereas the adhesive of the present invention contains a polyhydric alcohol compound (D) together with a polyhydric isocyanate compound (C), and generates polyurethane after application. , it is possible to improve the applicability to the film base material.

The adhesive of the present invention is characterized by a light transmittance of 80% or more in the wavelength range of 250 to 450 nm. The inventors have found that when light absorption occurs in the wavelength range of 250 to 450 nm, the absorbed energy activates dissolved oxygen in the adhesive, making it easier to generate active oxygen such as ozone and oxygen radicals. Do you get it. When an adhesive containing active oxygen is treated with hot water, oxidative deterioration of the adhesive layer and the film base material interface on the adhesive layer side is accelerated, resulting in a decrease in adhesion. Therefore, in order to improve the adhesion with the film substrate after hot water treatment, it is required that the light transmittance in the wavelength range of 250 to 450 nm is high, specifically, 80% or more.

First, each component of the adhesive of the present invention will be explained.

[Resin (A)]
The resin (A) has an ethylenically unsaturated group and a hydrophilic group. Here, examples of the "hydrophilic group" in the present invention include an amino group, a mercapto group, a carboxy group, a sulfo group, a phosphoric acid group, and a hydroxyl group. You may have two or more types of these. Among these, highly polar carboxy groups and hydroxyl groups are preferred, and it is more preferred to have both of these groups.

The acid value of the resin (A) is determined from the viewpoint of increasing wettability to the film base material and interaction with functional groups on the surface of the film base material, and further improving adhesion with the film base material after hot water treatment. It is preferably 30 mgKOH/g or more, more preferably 60 mgKOH/g or more, and even more preferably 75 mgKOH/g or more. On the other hand, the acid value of the resin (A) suppresses polarity to an appropriate level to suppress agglomeration and precipitation in the adhesive, suppress the occurrence of cracks caused by agglomeration and precipitation, and improve adhesion to the film base material after hot water treatment. From the viewpoint of further improving properties, the amount is preferably 250 mgKOH/g or less, more preferably 200 mgKOH/g or less, and even more preferably 150 mgKOH/g.

Here, the acid value of the resin (A) in the present invention can be determined in accordance with the neutralization titration method described in Test Method Section 3.1 of JIS K 0070:1992.

The acid value of the resin (A) can be adjusted to a desired range by, for example, appropriately selecting the type of raw material monomer, copolymerization ratio, amount of polymerization initiator used in polymerization, type of polymerization solvent, resin purification method, etc. I can do it.

From the viewpoint of further improving the adhesion with the film base material after hot water treatment, it is preferable to suppress deformation, thermal expansion and moisture absorption of the cured product, and the glass transition temperature (Tg) of the resin (A) is high. is preferred. Specifically, the Tg of the resin (A) is preferably 60°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. On the other hand, the Tg of the resin (A) is preferably 150°C or less, more preferably 140°C or less, and 130°C or less, from the viewpoint of suppressing the occurrence of cracks and further improving the adhesion with the film base material after hot water treatment. It is more preferable that the temperature is below ℃.

Here, the Tg of the resin (A) in the present invention can be determined using a differential scanning calorimeter (DSC) in accordance with JIS K 7121:2012.

The Tg of the resin (A) varies depending on, for example, the weight average molecular weight, degree of dispersion, rigidity of the main chain, steric hindrance of the side chain, type, symmetry, and polarity of the functional group, and therefore depends on the type of raw material monomer and It can be adjusted to a desired range by appropriately selecting the copolymerization ratio, polymerization method, polymerization conditions, etc.

The iodine value of the resin (A) is 0.5 mol / kg or more is preferable, and 1.0 mol/kg or more is more preferable. On the other hand, the iodine value of the resin (A) is preferably 3.0 mol/kg or less, and 2.5 mol/kg or less, from the viewpoint of suppressing the occurrence of cracks and further improving the adhesion with the film base material after hot water treatment. kg or less is more preferable.

Here, the iodine value of the resin (A) in the present invention can be determined by the method described in Section 6 of JIS K 0070:1992.

The iodine value of the resin (A) can be adjusted within a desired range, for example, by appropriately setting the amount of ethylenically unsaturated groups.

Examples of the main chain structure of the resin (A) include acrylic resin, styrene acrylic resin, styrene maleic resin, rosin-modified maleic resin, rosin-modified acrylic resin, epoxy resin, polyester resin, polyurethane resin, phenol resin, etc. Can be mentioned. Among these, acrylic resins, styrene-acrylic resins, and styrene-maleic resins are preferred from the viewpoint of ease of monomer availability, ease of synthesis, transparency, and heat resistance.

The acrylic resin, styrene acrylic resin, or styrene maleic acid resin having an ethylenically unsaturated group and a hydrophilic group can be produced, for example, by the following method. First, a resin having a hydrophilic group is obtained by copolymerizing a raw material monomer of a desired resin and a monomer having a hydrophilic group using a radical polymerization initiator. Examples of the monomer having a carboxyl group as a hydrophilic group include (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate, and acid anhydrides thereof. Examples of the monomer having a hydroxyl group as a hydrophilic group include 2-hydroxyethyl (meth)acrylate. Examples of monomers having an amino group as a hydrophilic group include dimethylaminoethyl (meth)acrylate. Examples of monomers having a mercapto group as a hydrophilic group include 2-(mercaptoacetoxy)ethyl (meth)acrylate. Examples of monomers having a sulfo group as a hydrophilic group include (meth)acrylamide t-butylsulfonic acid. Examples of the monomer having a phosphoric acid group as a hydrophilic group include 2-(meth)acryloxethyl acid phosphate. Furthermore, by adding an ethylenically unsaturated compound having a glycidyl group, (meth)acrylic acid chloride, allyl chloride, etc. to the hydrophilic group in the resin having a hydrophilic group, ethylenically unsaturated groups and hydrophilic groups can be added. A resin having a functional group can be obtained. Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl (meth)acrylate, allyl glycidyl ether, glycidyl crotonate, and glycidyl isocrotonate. Here, "(meth)acrylic acid" is a generic term for acrylic acid and methacrylic acid, and "(meth)acrylate" is a generic term for acrylate and methacrylate.

The weight average molecular weight of the resin (A) is preferably 5,000 or more and 100,000 or less. By setting the weight average molecular weight of the resin (A) to 5,000 or more, the crosslinking density is increased to suppress deformation, thermal expansion, and moisture absorption of the cured product, and the adhesion to the film base material after hot water treatment is improved. can be improved. The weight average molecular weight of the resin (A) is more preferably 10,000 or more, and even more preferably 20,000 or more. On the other hand, by setting the weight average molecular weight of the resin (A) to 100,000 or less, the coatability of the adhesive is improved and an adhesive layer with a uniform thickness can be formed. Thereby, stress concentration due to curing shrinkage and thermal expansion can be alleviated, and adhesion to the film base material after hot water treatment can be further improved. The weight average molecular weight of the resin (A) is more preferably 75,000 or less, and even more preferably 50,000 or less.

Here, the weight average molecular weight of the resin (A) in the present invention refers to a polystyrene equivalent value measured using gel permeation chromatography (GPC).

The degree of dispersion (PDI) defined by the weight average molecular weight/number average molecular weight of the resin (A) is determined from the viewpoint of suppressing the occurrence of cracks and further improving the adhesion with the film base material after hot water treatment. It is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. On the other hand, PDI of the resin (A) is used in 10. from the viewpoint of making the crosslinking density uniform, suppressing deformation, thermal expansion, and moisture absorption of the cured product, and further improving the adhesion with the film base material after hot water treatment. It is preferably 0 or less, more preferably 8.0 or less, and even more preferably 7.0 or less.

The content of the resin (A) in the adhesive of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. On the other hand, the content of the resin (A) in the adhesive of the present invention is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. By setting the content of the resin (A) within the above range, it is possible to suppress the occurrence of cracks and further improve the adhesion to the film base material after hot water treatment.

[Ethylenically unsaturated compound (B)]
The ethylenically unsaturated compound (B) is preferably a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups, which increases crosslinking density, suppresses deformation, thermal expansion, and moisture absorption of the cured product, and Adhesion to the film base material after water treatment can be further improved. From the viewpoint of increasing the fluidity of the adhesive and further improving the coating properties, the number of (meth)acryloyl groups is preferably 6 or less, more preferably 4 or less. In the present invention, any compound having two or more (meth)acryloyl groups is classified as an ethylenically unsaturated compound (B) even if it is a compound having two or more hydroxyl groups.

Examples of polyfunctional (meth)acrylates include hydrophobic (meth)acrylates and hydrophilic (meth)acrylates. It is preferable to select an appropriate one from among these in consideration of compatibility with the resin (A), and it is possible to improve the applicability to a base material having high surface free energy.

The hydrophobic (meth)acrylate in the present invention refers to a (meth)acrylate that does not have atoms other than carbon and hydrogen in the skeleton excluding the (meth)acryloyl group.

Examples of the hydrophobic (meth)acrylate include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and 1,10 -Decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tetra(meth)acrylate ) acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like. Among these, tricyclodecane dimethanol di(meth)acrylate is preferred. Note that these alkylene oxide adducts are classified as hydrophilic (meth)acrylates, which will be described later.

The hydrophilic (meth)acrylate in the present invention refers to a (meth)acrylate having an oxygen atom, a nitrogen atom, etc. in the skeleton excluding the (meth)acryloyl group.

Examples of the functional groups of the hydrophilic (meth)acrylate include ethylene oxide group, propylene oxide group, hydroxy group, carboxyl group, carbonyl group, amide group, and amine group. Among these, the ethylene oxide group is more preferred since it maintains appropriate compatibility with the resin (A) and can impart appropriate viscosity to the ink.

Examples of hydrophilic (meth)acrylates include pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerin di(meth)acrylate, diglycerin tri(meth)acrylate, and diglycerin tetra(meth)acrylate. Acrylate, 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl hydroxypivalate glycol di(meth)acrylate, N-acryloyloxyethyl Hexahydrophthalimide, acryloylmorpholine, oxazolidone acrylate, acrylamide, methacrylamide, butoxymethylacrylamide, hydroxyethylacrylamide, dimethylaminopropyl (meth)acrylamide, diacetone acrylamide, hydroxymethyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, hydroxy Propyl (meth)acrylamide, dihydroxyethylene bis(meth)acrylamide dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 6-(diethylamino)hexyl (meth)acrylamide, isocyanuric acid diacrylate, isocyanuric acid triacrylate, etc. , and their alkylene oxide adducts. Among these, pentaerythol tri(meth)acrylate and diglycerin tetra(meth)acrylate are particularly preferred because they maintain appropriate compatibility with resins and hydrophobic monomers and can impart appropriate viscosity to the ink.

The molecular weight of the ethylenically unsaturated compound (B) is preferably 200 or more and 1,000 or less. By setting the molecular weight to 200 or more, compatibility with the resin (A) can be improved. The molecular weight is more preferably 300 or more. On the other hand, by setting the molecular weight to 1,000 or less, the fluidity of the adhesive can be increased and the applicability can be further improved. The molecular weight is more preferably 800 or less.

The content of the ethylenically unsaturated compound (B) in the adhesive of the present invention is preferably 3% by mass or more. On the other hand, the content of the ethylenically unsaturated compound (B) in the adhesive of the present invention is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. By setting the content of the ethylenically unsaturated compound (B) within the above range, it is possible to suppress the occurrence of cracks and further improve the adhesion to the film base material after hot water treatment.

[Polyvalent isocyanate compound (C)]
The polyvalent isocyanate compound (C) in the present invention refers to a compound having two or more isocyanate groups, and is a component whose molecular weight is increased by an addition reaction. In addition, in the present invention, as long as the compound has two or more isocyanate groups, even if it is a resin having a hydrophilic group or ethylenically unsaturated group, or a compound having two or more hydroxyl groups, the polyvalent isocyanate compound (C) shall be classified into The weight average molecular weight of the polyvalent isocyanate compound (C) is preferably 300 or more, more preferably 600 or more, and even more preferably 1,000 or more, from the viewpoint of suppressing elution when remaining in the cured product of the adhesive. On the other hand, the weight average molecular weight of the polyvalent isocyanate compound (C) is preferably 5,000 or less, more preferably 4,500 or less, and 3,500 or less, from the viewpoint of increasing the fluidity of the adhesive and improving the coating properties. is even more preferable.

Examples of the polyvalent isocyanate compound (C) include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polyhydric alcohol additions thereof. Examples include isocyanurate body, isocyanurate body, biuret body, and the like. Two or more types of these may be contained.

The content of the polyvalent isocyanate compound (C) in the adhesive of the present invention is preferably 20% by mass or more from the viewpoint of further improving the curing sensitivity of the adhesive and the adhesion to the film base material after hot water treatment. , more preferably 40% by mass or more. On the other hand, the content of the polyvalent isocyanate compound (C) in the adhesive of the present invention is preferably 80% by mass or less, and 70% by mass or less, from the viewpoint of suppressing elution when remaining in the cured product of the adhesive. is more preferable.

[Polyhydric alcohol compound (D)]
The polyhydric alcohol compound (D) in the present invention refers to a compound having two or more hydroxyl groups. However, as mentioned above, even when having two or more hydroxyl groups, a compound having two or more (meth)acryloyl groups is included in the ethylenically unsaturated compound (B), and a compound having two or more isocyanate groups is They shall be classified into valent isocyanate compounds (C).

From the viewpoint of improving compatibility with the resin (A), the molecular weight of the polyhydric alcohol compound (D) is preferably 500 or more, more preferably 800 or more, and even more preferably 1,500 or more. On the other hand, the molecular weight of the polyhydric alcohol compound (D) is preferably 5,000 or less, more preferably 3,500 or less, and even more preferably 3,000 or less, from the viewpoint of increasing the fluidity of the adhesive and improving the coating properties. preferable.

Examples of the polyhydric alcohol compound (D) include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, neopentyl glycol, glycerin, structural isomers thereof, and modified products in which a portion thereof is modified to ether; Examples include modified products in which some of them are ester-modified. Two or more types of these may be contained.

The urethane compound, which is a reaction product of polyhydric isocyanate (C) and polyhydric alcohol compound (D), has high flexibility, so it is difficult to bond the film base material and adhesive layer during and after curing the adhesive with hot water treatment. Stress generated at the interface can be relaxed, and adhesion to the film base material after curing can be improved. The total content of the polyvalent isocyanate compound (C) and the polyhydric alcohol compound (D) in the adhesive of the present invention is determined by the interface between the base material and the adhesive layer due to curing shrinkage, thermal expansion, and moisture absorption of the adhesive. From the viewpoint of alleviating the stress generated, the amount is preferably 50% by mass or more, and more preferably 60% by mass or more. On the other hand, the total content of the polyvalent isocyanate compound (C) and the polyhydric alcohol compound (D) in the adhesive of the present invention is preferably 90% by mass or less, and 80% by mass or less, from the viewpoint of suppressing gelation of the adhesive. It is more preferably less than % by mass.

The adhesive of the present invention contains a polyvalent isocyanate compound (C) and a polyhydric alcohol compound (D), respectively. Adhesives containing a urethane compound, which is a reaction product of a polyvalent isocyanate compound (C) and a polyhydric alcohol compound (D), tend to have increased flexibility of the cured product and improved adhesion to the film base material. On the other hand, it has a high viscosity and is difficult to apply. As mentioned above, in the present invention, the polyhydric alcohol compound (D) is contained together with the polyhydric isocyanate compound (C), which is a precursor of the urethane compound, and polyurethane is produced after coating, so the applicability to the film base material is improved. can be improved.

[Additive]
The adhesive of the present invention may further contain additives such as a polymerization inhibitor, a surfactant, a wax, an antifoaming agent, a transferability improver, a leveling agent, and a solvent, as required.

Examples of the polymerization inhibitor include hydroquinone, hydroquinone monoester, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-phenylnaphthylamine, 2,6-di-t-butyl-p-methylphenol, Examples include chloranil and pyrogallol. Two or more types of these may be contained.

The content of the polymerization inhibitor in the adhesive of the present invention is preferably 0.001% by mass or more and 5% by mass or less.

[Light transmittance]
The adhesive of the present invention has a light transmittance of 80% or more in the wavelength range of 250 to 450 nm. As mentioned above, when light absorption occurs in the wavelength range of 250 to 450 nm, dissolved oxygen in the adhesive is activated by the absorbed energy, and active oxygen such as ozone and oxygen radicals are likely to be generated. The generated active oxygen promotes oxidative deterioration of the adhesive layer and the film base material interface on the adhesive layer side by hot water treatment, and reduces the adhesion with the film base material. It is characterized by suppressing light absorption in the wavelength range of 250 to 450 nm, that is, by increasing the light transmittance, specifically to 80% or more. From the viewpoint of further improving the adhesion to the film substrate after hot water treatment, the light transmittance is preferably 85% or more, more preferably 90% or more.

Here, the light transmittance in the wavelength range of 250 to 450 nm in the present invention can be measured with a spectrophotometer.

In order to keep the light transmittance of the adhesive in the wavelength range of 250 to 450 nm within the above range, the adhesive must contain compounds that are intramolecularly cleaved by light in this wavelength range, compounds that cause intramolecular hydrogen abstraction, and compounds that have an electron transfer mechanism. Preferably, it does not substantially contain it. Examples of such compounds include benzoin derivatives, benzyl ketal, α-hydroxyacetophenone, α-aminoacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, thioxanthone, Acylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, titanocenes, ortho-acyloxime, benzophenone, Michler's ketone, triarylsulfonium salt, diaryliodonium salt, Cyanine dyes, merocyanine dyes, coumarin dyes, benzylidene ketone dyes, squalium dyes, thiapyrylium dyes, porphyrin dyes, trichloromethyltriazine, N-phenylglycine, borate salts, anthracene, naphthalene, perylene, phenothiazine, etc. Can be mentioned. Moreover, the term "substantially free" as used herein means that the total content in the adhesive is 10 mass ppm or less.

[viscosity]
The viscosity of the adhesive of the present invention at a temperature of 35° C. is preferably 100 mPa·s or more and 10,000 mPa·s or less. By setting the viscosity of the adhesive to 100 mPa·s or more, the thickness of the adhesive layer can be easily adjusted when forming the adhesive layer of the laminate described later. The viscosity of the adhesive is more preferably 150 mPa·s or more. On the other hand, by setting the viscosity of the adhesive to 10,000 mP·s or less, the fluidity of the adhesive can be increased and the applicability can be further improved. The viscosity of the adhesive is more preferably 5,000 mPa·s or less.

The viscosity of the adhesive can be adjusted to a desired range by, for example, using the above-mentioned preferred components, or adjusting the content of each component within the above-mentioned preferred ranges.

[Adhesive manufacturing method]
The adhesive of the present invention can be prepared by, for example, stirring the above-mentioned resin (A), ethylenically unsaturated compound (B), polyvalent isocyanate compound (C), polyhydric alcohol compound (D), and other components as necessary. It can be obtained by mixing. The stirring and mixing is preferably performed under a nitrogen atmosphere. Stirring and mixing may be performed at room temperature, or may be heated to such an extent that each component can be uniformly mixed in a short time. The stirring and mixing time is generally about 10 minutes to several hours.

[Laminated body]
The adhesive of the present invention has a first base material coated with active energy ray curable ink (hereinafter sometimes abbreviated as "ink") on at least a portion thereof, and a second base material, which is a layer of an adhesive layer. It can be suitably used in the adhesive layer of a laminate formed by laminating the adhesive layer through the adhesive layer. Either the first base material or the second base material may be a film base material, or both the first base material and the second base material may be film base materials.

Examples of the first base material include paper, plastic film, metal plates, metal foils, and laminates thereof. Examples of paper include art paper, coated paper, cast paper, synthetic paper, newsprint, metal-deposited paper on which the metal described below is deposited, and plastic film laminated paper on which a plastic film described below is laminated. It will be done. Examples of plastic films include films made of plastics such as polyethylene terephthalate, polyethylene, polyester, polyamide, polyimide, polystyrene, polypropylene, polycarbonate, and polyvinyl acetal, metal-deposited plastic films on which the metals described below are deposited, and polychloride films. Examples include gas barrier films coated with vinylidene, polyvinyl alcohol, and ethylene vinyl alcohol copolymers. The surface of these plastic films may be subjected to adhesion-facilitating treatment such as primer coating, corona discharge treatment, plasma treatment, or the like. Examples of the metal plate and metal foil include plates and foils made of metals such as aluminum, zinc, and copper, and oxides of these metals. Among these, plastic films such as polyester, polyethylene, and polypropylene, gas barrier films, and the like are preferred from the viewpoint of printability, appearance quality, and content protection.

The thickness of the first base material in the laminate of the present invention is preferably 10 μm or more and 30 μm or less.

The ink in the laminate of the present invention preferably contains an acrylic resin, a polyfunctional (meth)acrylate, and a pigment.

Such an ink can be obtained, for example, by heating and dissolving the above-mentioned components and other additives as necessary at 5 to 100°C, and then homogeneously mixing and dispersing the mixture using a stirring/kneading machine. be able to. Examples of the stirring/kneading machine include a kneader, three-roll mill, ball mill, planetary ball mill, bead mill, roll mill, attriter, sand mill, gate mixer, paint shaker, homogenizer, and revolution type stirrer. After mixing and dispersing or during the process of mixing and dispersing, defoaming is preferably carried out under vacuum or reduced pressure conditions.

Examples of the second base material include stretched films such as stretched polyamide film, stretched polyester film, and stretched polyolefin film, metal-deposited plastic films, metal films such as copper foil and aluminum foil, and unstretched polypropylene films. , a linear low-density polyethylene film, a heat-melt film (sealant film) such as a low-density polyethylene film, and the like. Among these, unstretched polypropylene film, linear low-density polyethylene film, low-density polyethylene film, and the like are preferred from the viewpoint of content protection and bag-making processability.

The adhesive layer in the laminate of the present invention is a layer obtained by applying the above-described adhesive of the present invention, and when the adhesive contains a solvent, it is preferable that the solvent is removed. The thickness of the adhesive layer is preferably 0.1 μm or more, more preferably 1.0 μm or more, from the viewpoint of further improving coating properties. On the other hand, the thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of further improving the curing reaction caused by active energy rays.

[Method for manufacturing laminate]
The method for manufacturing a laminate of the present invention includes:
Step (1) Applying active energy ray-curable ink to at least a portion of the first substrate Step (3): Applying active energy ray-curable ink to at least a portion of at least one side of the first substrate. Step (4) of applying the aforementioned adhesive to form an adhesive layer: Step (5) of laminating a second base material on the first base material on which the adhesive layer has been formed: Step (5) of laminating the first base material and It is preferable to include the steps of irradiating the laminate of the second base material with active energy rays in this order. It is more preferable to perform step (1), step (3), step (4), and step (5) in this order in-line.

Between step (1) and step (3),
Step (2): It is preferable to include a step of irradiating the first base material coated with the ink with active energy rays.

The first aspect of the method for manufacturing a laminate of the present invention includes step (1), step (2), step (3), step (4), and step (5).

Step (1) is a printing step of applying ink to the first base material. The ink may be applied to the necessary locations according to the pattern, and does not need to be applied to the entire surface of the laminate. Examples of the ink application method include printing methods such as flexo printing, planographic printing, gravure printing, and screen printing, and bar coater application. Among these, lithographic printing is preferred. Examples of planographic printing methods include water planographic printing and waterless planographic printing, with waterless planographic printing being preferred.

Step (2) is an ink curing step of curing the ink applied in step (1) with active energy rays, and is preferably performed immediately after step (1). As the active energy ray, one having excitation energy necessary for the curing reaction can be used, and for example, an electron beam can be preferably used. By using an electron beam, curing sensitivity can be improved. When irradiating with an electron beam, an electron beam device having an energy beam with an accelerating voltage of 80 to 300 kV is preferably used. The absorbed dose of the printed matter is preferably 10 kGy or more, which provides good curing sensitivity of the ink and adhesive. Moreover, 70 kGy or less is preferable because it has little influence on the film base material.

Step (3) is an adhesive application step of applying the adhesive of the present invention to at least one side of the printed first base material obtained in step (2). The adhesive may be applied to either side of the first base material, but from the viewpoint of suppressing the uncured ink applied in step (1) from adhering to equipment during transportation between steps, Preferably, an adhesive is applied to the ink-applied surface.

Step (4) is a lamination step of laminating the second base material.

Step (5) is an adhesive curing step in which the adhesive applied in step (3) is cured by active energy rays, and is preferably performed immediately after step (4). A preferred embodiment of step (5) is the same as step (2).

In the first embodiment, steps (1) to (2) for obtaining a first base material having a cured ink product, and steps (3) for obtaining a laminate in which the first base material and the second base material are laminated. By performing step (5) separately, when a printing defect occurs in step (1), processing loss of the adhesive and the second base material can be reduced.

The second aspect of the method for manufacturing a laminate of the present invention includes the above-described steps (1), (3), (4), and (5) in this order. In the second embodiment, in step (5), ink curing and adhesive curing are performed simultaneously. Steps (1), (3), (4), and (5) are preferably performed in a series of manufacturing processes, i.e., in-line, to reduce lead time and improve productivity. be able to. Further, compared to an offline manufacturing method in which steps (1) and (4) are performed discontinuously, processing loss caused in step (4) can be reduced. Furthermore, in step (5), since the adhesive layer and the second base material are present on the ink surface, insufficient curing caused by the ink surface being exposed to oxygen is suppressed, and the adhesion between the second base material and the ink is suppressed. It is possible to improve the properties and hardenability of ink.

In any embodiment of the method for producing a laminate of the present invention, the film laminate obtained in step (5) is preferably heat-treated in an environment of 40° C. or higher and 60° C. or lower. By heat treatment, the adhesion to the film base material can be improved by the reaction between the polyvalent isocyanate compound (C) and the polyhydric alcohol (D) in the adhesive layer.

Hereinafter, the present invention will be specifically explained with reference to Examples. However, the present invention is not limited to these. The evaluation method for each example and comparative example is as follows.

(1) Weight average molecular weight Mw, number average molecular weight Mn, dispersity PDI
For the resins obtained in Synthesis Examples 1 to 18, the weight average molecular weight Mw and number average molecular weight Mn in terms of polystyrene were measured by gel permeation chromatography (GPC) using Shodex KF-803 as a column and tetrahydrofuran as a mobile phase. did. Further, the degree of dispersion PDI was calculated using Mw/Mn.

(2) Acid value The acid value of the resins obtained in Synthesis Examples 1 to 18 was measured according to the neutralization titration method of JIS K 0070:1992 Test Method Section 3.1.

(3) Tg
The glass transition temperature Tg of the resins obtained in Synthesis Examples 1 to 18 was measured in accordance with JIS K 7121:2012. Approximately 5 mg of resin was packed into an aluminum pan using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments). To condition the sample, the temperature was raised from 30°C to 200°C at a rate of 10°C/min and then held at 200°C for 5 minutes, and the temperature was lowered from 200°C to 0°C at a rate of 10°C/min and then held at 0°C for 10 minutes. . Then, the temperature was raised from 0°C to 200°C at a rate of 10°C/min. In the DSC curve at that time, Tg And so.

(4) Iodine value The iodine value of the resins obtained in Synthesis Examples 1 to 18 was measured in accordance with the method described in Section 6 of JIS K 0070:1992.

(5) Light transmittance The active energy ray-curable adhesive obtained in each example and comparative example was applied to a spectrophotometer cell (manufactured by GL Sciences, model number: S10-SQ-1, material: synthetic quartz, Using a spectrophotometer U-4100 manufactured by Hitachi, Ltd., the light transmittance was measured every 1 nm in the wavelength range of 250 nm to 450 nm, and the minimum value was calculated.

(6) Viscosity The viscosity of the active energy ray-curable adhesives obtained in each example and comparative example was measured at a temperature of 35° C. and a rotation speed of 50 rpm using a B-type viscometer Model RVDV2+ manufactured by BROOKFIELD Co., Ltd. .

(7) Applicability The active energy ray-curable adhesive obtained in each Example and Comparative Example was coated on a 12 μm thick polyamide film (manufactured by Unitika Co., Ltd., ONM) using a #8 bar coater. After coating to a thickness of 10 μm, the coated surface was visually observed at a distance of 250 mm in the coating direction and 170 mm in the width direction with respect to the coating direction, and the coating properties were evaluated according to the following criteria.
C (Poor): Any of horizontal streak unevenness, bounce, bubbles, or defects are observed.
B (slightly good): No horizontal streak unevenness, bounce, bubbles, or defects were observed, but leveling performance was insufficient.
A (Good): No horizontal streak unevenness, bounce, bubbles, or defects were observed, and leveling property was good.

(8) Adhesion to film substrate after hot water treatment The film laminates obtained in each example and comparative example were treated in hot water at 95°C for 30 minutes (hot water treatment), and the width was 1. A 5 cm sample was cut. Part of the first base material and second base material of the sample was peeled off, and the peel strength was measured using Tensilon (manufactured by AND Co., Ltd., RTG-1210) under the conditions of a load cell of 50 N and a speed of 300 mm/min. The adhesion to the film substrate after hot water treatment was evaluated according to the following criteria.
D (Poor): Adhesion force is less than 1.0N.
C (slightly poor): Adhesion strength is 1.0N or more and less than 2.0N.
B (good): Adhesion force is 2.0N or more and less than 3.0N.
A (slightly good): Adhesion strength is 3.0N or more and less than 4.0N.
S (very good): Adhesion strength is 4.0N or more.

The raw materials used in each example and comparative example are shown below.

[resin]
(Synthesis example 1: resin 1)
In a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas introduction tube, 150 mol parts of propylene glycol monomethyl ether acetate (hereinafter referred to as PGMEA) as a solvent, 25 mol parts of methyl methacrylate as raw material monomers, 25 mol parts of styrene, 50 mol parts of methacrylic acid was charged, and 4 mol parts of 2,2'-azobis(2-methylbutyronitrile) (hereinafter referred to as ABN-E) was added as a polymerization initiator. Drop polymerization was carried out at 140°C for 1.5 hours under reflux and stirring, and the mixture was kept at a temperature for 1 hour to obtain a copolymer. Next, glycidyl methacrylate in an amount of 0.55 equivalent to the carboxyl group of the obtained copolymer was added to the reaction vessel and stirred at 80°C for 5 hours to cause an addition reaction between the ethylenically unsaturated group and the hydrophilic group (carboxyl group). and hydroxyl group) was obtained. Table 1 shows the results of evaluation of the obtained resin by the method described above.

(Synthesis Examples 2 to 18: Resins 2 to 18)
Resins 2 to 18 were obtained in the same manner as Resin 1 except that the type and composition of the raw material monomers were changed as shown in Tables 1 to 2. The results of evaluation of the obtained resin by the method described above are shown in Tables 1 and 2.

The abbreviations listed in Tables 1 and 2 are as follows.
St: Styrene MMA: Methyl methacrylate MAA: Methacrylic acid GMA: Glycidyl methacrylate PGMEA: Propylene glycol monomethyl ether acetate 2-EHA: 2-ethylhexyl acrylate ABN-E: 2,2'-azobis(2-methylbutyronitrile) )

(Resin 19)
Resin 19: Polyurethane resin (“Nipporan” (registered trademark) 2304 manufactured by Tosoh Corporation, weight average molecular weight: 56,000, number average molecular weight: 11,200, PDI: 5.0, Tg: -23°C, acid value : 0mgKOH/g, iodine value: 0mol/kg)
[Ethylenically unsaturated compound (B)]
B1: Ethylene oxide modified trimethylolpropane triacrylate (“Miramer” (registered trademark) M3130 (manufactured by MIWON)
[Polyvalent isocyanate compound (C)]
C1: Solvent-free lamination adhesive (“Takenate” (registered trademark) A-244B (manufactured by Mitsui Chemicals, Inc.), weight average molecular weight 3,200)
[Polyhydric alcohol compound (D)]
D1: Solvent-free lamination adhesive (“Takelac” (registered trademark) A-244A (manufactured by Mitsui Chemicals, Inc.), aromatic ether type, weight average molecular weight 2,000)
[Photopolymerization initiator]
E1: α-hydroxycyclohexylacetophenone (manufactured by Tokyo Kasei Co., Ltd.)
[solvent]
F1: Methyl isobutyl ketone (manufactured by Tokyo Kasei Co., Ltd.)
G1: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd.).

(Production Example 1: Active energy ray curable ink)
Resin 1: 11.7 parts by mass, ethylenically unsaturated compound isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., "Light Acrylate" (registered trademark) IB-XA): 67.1 parts by mass, pigment Seika Cyanine Blue 4920 (manufactured by Dainichiseika Co., Ltd.): 18.0 parts by mass, extender pigment "Micro Ace" (registered trademark) P-8 (manufactured by Nippon Talc Co., Ltd.): 3.0 parts by mass, and polymerization inhibitor p-methoxy Phenol (manufactured by Wako Pure Chemical Industries, Ltd.): Weigh out 0.1 part by mass, and use a three-roll mill "EXAKT" (registered trademark) M-80S (manufactured by EXAKT) to adjust the setting of "gap 1" on the same device. '' to obtain an active energy ray-curable ink.

<Base film>
First base film A: Polyamide film (manufactured by Unitika Co., Ltd., ONM, thickness 12 μm)
Second base film B: Low density polyethylene film LL-XUMN (trade name) (manufactured by Futamura Co., Ltd., thickness 50 μm).

[Example 1]
Resin 1, B1, C1, and D1 having the composition shown in Table 3 were weighed in a glass container and stirred at room temperature in a nitrogen atmosphere for 1 hour to obtain an active energy ray-curable adhesive. The light transmittance, viscosity, and applicability of the obtained active energy ray-curable adhesive were evaluated by the methods described above.

A waterless planographic printing plate (TAC-VG5, manufactured by Toray Industries, Inc.) was attached to a lithographic rotary printing press (CI-8, manufactured by COMEXI). Using the active energy ray-curable ink obtained in Production Example 1 on the first base film A, back printing was performed for 1,000 m under the conditions of a printing temperature of 30°C, a printing speed of 200 m/min, and an ink supply rate of 50%. After printing a test pattern (175 lines with 1% to 50% halftone dots, 30 μm wide thin line, 120 μm diameter independent points, 300 μm wide punch line, and solid area) at an accelerating voltage of 110 kV and a dose of 30 kGy. The ink was cured by irradiation with an electron beam, and a printed matter was obtained. However, the ink supply amount was adjusted so that the indigo color reflection density in the solid area was 1.8.

The obtained printed material was coated with an active energy ray-curable adhesive to a thickness of about 10 μm using a #8 bar coater, and then the second base film B was laminated thereon. Thereafter, under the conditions of an accelerating voltage of 110 kV and a dose of 30 kGy, electron beams were irradiated from the first base film side and cured at 40°C for 72 hours, and the first base film A/ink A/active energy ray-curable adhesive A film laminate in which the layers/second base film B were laminated in order was obtained. Table 3 shows the results of evaluation of the obtained film laminate using the method described above.

[Examples 2 to 17]
An active energy ray-curable adhesive and a film laminate were obtained in the same manner as in Example 1, except that Resin 1 was changed as shown in Table 3. Table 3 shows the results evaluated by the method described above.

[Examples 18-19]
An active energy ray-curable adhesive and a film laminate were obtained in the same manner as in Example 1, except that the composition ratios of B1, C1, and D1 were changed as shown in Table 4. Table 4 shows the results evaluated by the method described above.

[Examples 20-21]
An active energy ray-curable adhesive and a film laminate were obtained in the same manner as in Example 1, except that the composition ratios of C1 and D1 were changed as shown in Table 4, and E1 shown in Table 4 was added. Table 4 shows the results evaluated by the method described above.

[Examples 22 to 24]
An active energy ray-curable adhesive and a film laminate were obtained in the same manner as in Example 1, except that the composition ratios of B1, C1, and D1 were changed as shown in Table 4. Table 4 shows the results evaluated by the method described above.

[Comparative Examples 1 to 5]
An active energy ray-curable adhesive and a film laminate were obtained in the same manner as in Example 1 except that the compositions were changed to those shown in Table 4. Table 4 shows the results evaluated by the method described above.
A film laminate was obtained in the same manner as in Example 1, except that the active energy ray-curable adhesive was weighed. Table 4 shows the evaluation results of the obtained film laminate. Since the light transmittance is 20%, the coating property is "good". The adhesion is "slightly good" at 3.2N immediately after curing treatment (initial stage), and after treatment at 95°C for 30 minutes (after hot water treatment). It was 0.1N and was ``defective''.

Claims (7)

Light with a wavelength of 250 to 450 nm containing a resin (A) having an ethylenically unsaturated group and a hydrophilic group, an ethylenically unsaturated compound (B), a polyvalent isocyanate compound (C) and a polyhydric alcohol compound (D) An active energy ray-curable adhesive with a transmittance of 80% or more. The active energy ray-curable adhesive according to claim 1, wherein the resin (A) has a carboxyl group and a hydroxyl group as the hydrophilic group. The active energy ray-curable adhesive according to claim 1 or 2, wherein the resin (A) has an acid value of 30 mgKOH/g or more and 250 mgKOH/g or less. The active energy ray-curable adhesive according to claim 1 or 2, wherein the resin (A) has a glass transition temperature Tg of 60°C or more and 150°C or less. The active energy ray-curable adhesive according to claim 1 or 2, wherein the total content of the polyvalent isocyanate compound (C) and the polyhydric alcohol compound (D) is 50% by mass or more and 90% by mass or less. A method for producing a laminate in which a first base material, at least a portion of which is coated with active energy ray-curable ink, and a second base material are laminated via an adhesive layer, the method comprising:
Step (1): Applying active energy ray-curable ink to at least a portion of the first substrate Step (3): At least one side of the first substrate coated with at least a portion of active energy ray-curable ink Step (4) of applying the active energy ray-curable adhesive according to claim 1 or 2 to form an adhesive layer, and step (4): applying a second base material to the first base material on which the adhesive layer has been formed. Laminating process Step (5): A method for producing a laminate including the steps of irradiating the laminate of the first base material and the second base material with active energy rays in this order. 7. The method for manufacturing a laminate according to claim 6, wherein step (1), step (3), step (4), and step (5) are performed in-line in this order.