JP2025020863A - Active energy ray-curable varnish composition - Google Patents

Abstract

To impart "printing suitability" and "printed material quality" to a varnish composition used for the preparation of printed materials by Lamicoat processing.SOLUTION: The present invention provides an active energy ray-curable varnish composition for a laminate obtained by overlaying a polyolefin film onto a coating layer composed of the active energy ray-curable varnish composition formed on a substrate, curing the coating layer through active energy ray irradiation to form a cured layer, and then peeling the polyolefin film from the cured layer. The active energy ray-curable varnish composition comprises: (1) 10.0-40.0 mass% of a styrene-based resin (A) relative to the total composition, with the mass ratio of styrene being 95% or more, and the acid value being either 0 mgKOH/g or 0-10 mgKOH/g; (2) a polymerizable monomer (B) comprising a difunctional polymerizable compound (B1) with a polyol ethylene oxide adduct skeleton; (3) an initiator (C); and (4) 0.1-0.5 mass% of a silicone-based compound (D) relative to the total composition.SELECTED DRAWING: Figure 1

Description

The present invention relates to a varnish composition that can be cured with active energy rays (active energy ray-curable varnish composition), and more specifically, to an active energy ray-curable varnish composition used in the production of printed matter by lamicoating processing.

One method for producing printed matter is known as "Lamicoat (LC) processing" (Patent Document 1, etc.). In producing printed matter by Lamicoat processing, first, an active energy ray-curable varnish composition is coated on the surface of the substrate to be printed (Step A). Next, while a polyolefin film is pressed against the coating of the active energy ray-curable varnish composition (coating in a wet state before curing) coated on the surface of the substrate (Step B), active energy rays are irradiated onto the coating of the active energy ray-curable varnish composition through the polyolefin film, thereby turning the coating into a cured layer (Step C). After that, the polyolefin film is peeled off from the cured layer of the active energy ray-curable varnish composition (Step D).

Several proposals have been made for active energy ray-curable varnish compositions used in the creation of printed matter by lamicoating (see Patent Documents 2 to 6). Patent Document 2 discloses an active energy ray-curable varnish composition containing a chlorinated polypropylene resin with a specified chlorine content, and claims to obtain a cured product layer with excellent adhesion to the substrate, glossiness, cosmetic properties, and yellowing resistance. Patent Document 3 discloses an active energy ray-curable varnish composition containing a phosphoric acid compound, and claims to obtain a cured product layer with excellent adhesion to the substrate, glossiness, cosmetic properties, and yellowing resistance. Patent Document 4 discloses an active energy ray-curable varnish composition containing a specified styrene-acrylic resin, and claims to obtain a cured product layer with excellent adhesion to the substrate, glossiness of the coating film, cosmetic properties, and yellowing resistance. Patent Document 5 discloses an active energy ray-curable varnish containing a polar functional group-containing (meth)acrylic resin and an alkyl group-containing (meth)acrylic resin, and claims to obtain a cured product layer that can suppress deterioration of glossiness over time. Patent Document 6 discloses an active energy ray-curable varnish that contains a specific styrene-acrylic resin and a photopolymerizable monomer, and the varnish is said to have the fluidity required to achieve good cosmetic properties.

JP 2007-90162 A JP 2021-80354 A JP 2021-147494 A Patent No. 5978497 Patent No. 5617610 JP 2012-136618 A

Printed materials created by lamicoat processing are characterized by high surface leveling of the resulting cured layer, because the varnish applied to the substrate is cured while being pressed with a film; furthermore, it is said that it is possible to reduce the amount of curing energy and photopolymerization initiator required, because it is less susceptible to curing inhibition by oxygen.

In addition, the varnish composition used to create printed matter by lamicoating is required to have high "printing suitability," such as being easily cured by active energy rays (curability) and being easy to peel off the film from the cured coating (cured layer) (peelability); and, in addition, it is required to have high "print quality," such as high adhesion of the cured layer of the varnish formed on the substrate, high surface hardness of the cured layer (scratch resistance, etc.), high gloss, high slipperiness of the surface of the cured layer, no blocking even when the cured layers come into contact with each other, and, depending on the application of the printed matter, flexibility and stretchability of the cured layer (suppression of cracking of creases).

The present invention aims to impart the above-mentioned "printability" and "print quality" to a varnish composition used in producing printed matter by lamicoating. For example, when attempting to increase the flexibility or stretchability of the cured layer of the varnish composition, there is a tendency for the peelability of the film from the cured layer to decrease. The objective of the present invention is to maintain a good balance between "printability" and "print quality" by adjusting the composition of the varnish composition.

That is, the present invention relates to an active energy ray-curable varnish composition used for producing printed matter by lamicoating, as shown below.
[1] An active energy ray-curable varnish composition for a laminate obtained by overlaying a polyolefin film on a coating layer made of an active energy ray-curable varnish composition formed on a substrate, curing the coating layer by irradiation with active energy rays to form a cured material layer, and peeling the polyolefin film from the cured material layer,
An active energy ray-curable varnish composition containing the following (1) to (4): (1) 10.0 to 40.0 mass% of a styrene-based resin (A) relative to the entire composition, the styrene mass ratio being 95% or more and the acid value being 0 mgKOH/g or 0 to 10 mgKOH/g; (2) a polymerizable monomer (B) containing a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol; (3) 0.1 to 20.0 mass% of an initiator (C) relative to the entire composition; and (4) 0.1 to 0.5 mass% of a silicone-based compound (D) relative to the entire composition.

The present invention preferably relates to the following active energy ray-curable varnish composition.
[2] The active energy ray-curable varnish composition according to [1], wherein the styrene-based resin (A) is a styrene homopolymer.
[3] The active energy ray-curable varnish composition according to [1] or [2], wherein the styrene-based resin (A) has a mass average molecular weight of 3,000 to 8,000.

[4] The active energy ray-curable varnish composition according to any one of the above [1] to [3], wherein the polyol of the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol is a polyol having 4 to 8 carbon atoms.
[5] The active energy ray-curable varnish composition according to any one of the above [1] to [4], wherein the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol has an ethylene oxide addition number of 3 to 8.
[6] The active energy ray-curable varnish composition according to any one of [1] to [5], wherein the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol is a diacrylate of a 5-mol ethylene oxide adduct of 1,6-hexanediol (5EO-HDDA).
[7] The active energy ray-curable varnish composition according to any one of [1] to [6], wherein the content of the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of the polyol is 20.0 mass% or less based on the entire composition.

[8] The active energy ray-curable varnish composition according to any one of [1] to [7], wherein the initiator (C) has a hydroxyalkylphenone structure.
[9] The active energy ray-curable varnish composition according to any one of [1] to [8], wherein the content of the initiator (C) is 8.0 mass% or more based on the total mass of the composition.

[10] The active energy ray-curable varnish composition according to any one of [1] to [9], wherein the polymerizable monomer (B) further contains a tri- or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol.
[11] The active energy ray-curable varnish composition according to [10] above, wherein the polyol of the tri- or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol is trimethylolpropane.
[12] The active energy ray-curable varnish composition according to [10] or [11] above, wherein the tri- or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol has an ethylene oxide addition number of 1 to 12.
[13] The active energy ray-curable varnish composition according to any one of [10] to [12] above, wherein the content of the tri- or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of the polyol is 10.0 to 30.0 mass% based on the total mass of the composition.

The active energy ray-curable varnish composition of the present invention has high printability when producing printed matter by lami-coating, and can improve the print quality of printed matter obtained by lami-coating.

FIG. 2 is a diagram showing a method for producing a printed matter in the embodiment.

1. Composition of the active energy ray-curable varnish composition The active energy ray-curable varnish composition of the present invention (hereinafter, also simply referred to as the "varnish composition") contains at least 1) a styrene-based resin (A), 2) a polymerizable monomer (B), 3) an initiator (C), and 4) a silicone-based compound (D), and may further contain 5) other optional components.

1-1. Styrene-based resin (A)
The styrene resin (A) contained in the varnish composition is a resin containing styrene as a monomer constituent unit. The styrene constituting the monomer constituent unit of the styrene resin (A) may be styrene or other styrenes such as α-methylstyrene and vinylstyrene, and is preferably styrene.

The mass content of styrene in the styrene-based resin (A) is 95% or more, preferably 98% or more, and may be 100% (i.e., styrene homopolymer). When the mass content of styrene in the styrene-based resin (A) is 95% or more, the adhesion of the cured material layer in the printed matter obtained by lamicoating is likely to be increased, the film peelability is also improved, and the cured material layer is likely to have a high surface hardness (high scratch resistance); and the gloss of the printed matter is likely to be increased.

The acid value of the styrene-based resin (A) is 0 mgKOH/g or 0 to 10 mgKOH/g; preferably 0 mgKOH/g or 0 to 5 mgKOH/g; more preferably 0 mgKOH/g. In other words, if the styrene-based resin (A) is a styrene homopolymer, its acid value can be 0 mgKOH/g. The lower the acid value of the styrene-based resin (A), the higher the adhesion between the cured layer of the varnish composition and the substrate in the printed matter obtained by lamination processing, and the higher the scratch resistance of the cured layer.

The mass average molecular weight of the styrene-based resin (A) is not particularly limited, but may be 3,000 to 8,000. In order to increase the surface hardness of the cured layer of the varnish composition, it is preferable that the molecular weight of the styrene-based resin (A) is high; on the other hand, in order to reduce the viscosity of the varnish composition, it is preferable that the molecular weight of the styrene-based resin (A) is low.

The styrene-based resin (A) may or may not have other constituent units other than styrene as monomer constituent units. Examples of other constituent units include (meth)acrylic acid ester monomers. Examples of (meth)acrylic acid esters include alkyl (meth)acrylates having linear or branched alkyl chains such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, 2-heptyl, 2-ethylhexyl, 2-ethylbutyl, nonyl, dodecyl, lauryl, and stearyl; (meth)acrylates having amino groups such as 2-(N,N-dimethylamino)ethyl (meth)acrylate and 3-(N,N-dimethylamino)propyl (meth)acrylate; (meth)acrylates having hydroxyl groups such as 2-hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; and (meth)acrylates having epoxy groups and (meth)acrylates having amide groups.

The content (solid content) of the styrene-based resin (A) in the varnish composition is 10.0% by mass or more, preferably 15.0% by mass or more, based on the entire varnish composition; on the other hand, it is 40.0% by mass or less, preferably 30.0% by mass or less. In order to improve the film peelability and scratch resistance of the cured layer of the printed material, it is preferable to increase the content of the styrene-based resin (A). On the other hand, in order to improve the printing characteristics of the varnish composition and to increase the flexibility and elasticity of the cured layer to suppress cracking of the printed material, it is preferable to keep the content of the styrene-based resin (A) below a certain level.

1-2. Polymerizable monomer (B)
The polymerizable monomer (B) contained in the varnish composition may be a monomer or oligomer having at least one polymerizable reactive group, such as a (meth)acryloyl group, in the molecule. The polymerizable monomer (B) contains at least a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol; it is preferable that the polymerizable monomer (B) further contains a trifunctional or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol; and may contain another polymerizable compound (B3).

1-2-1. Bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol
At least a part of the polymerizable monomer (B) is a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol. The "ethylene oxide adduct skeleton of a polyol" refers to a molecular structure in which ethylene oxide (C ₂ H ₄ O) is added to a hydroxyl group of a polyol (polyhydric alcohol). The polyol of the bifunctional polymerizable compound (B1) may be either an aromatic or aliphatic polyol, but may be preferably an aliphatic polyol. The polyol of the bifunctional polymerizable compound (B1) preferably has 4 to 8 carbon atoms, and specific examples of the polyol include aliphatic diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,3-butanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, and polyethylene glycol, and aromatic diols such as bisphenol A and bisphenol F.

The number of ethylene oxides added to the polyol of the bifunctional polymerizable compound (B1) may be 1 or more, preferably 3 or more; preferably 8 or less. The more ethylene oxides added to the polyol of the bifunctional polymerizable compound (B1), the more likely it is that the flexibility and stretchability of the cured layer of the varnish composition will increase, and the more likely it is that cracks in the lines of the printed material will be suppressed. On the other hand, if the number of ethylene oxides added to the polyol of the bifunctional polymerizable compound (B1) is too large, the scratch resistance of the cured layer in the printed material will tend to decrease, or the film peelability from the cured layer will tend to decrease.

The bifunctional polymerizable compound (B1) may be a compound obtained by reacting an ethylene oxide adduct of a polyol with a compound having a polymerizable functional group (e.g., a (meth)acryloyl group); a compound obtained by esterifying an ethylene oxide adduct of a polyol with two (meth)acrylic acids is preferred. The (meth)acrylic acid is one or both of acrylic acid and (meth)acrylic acid. The bifunctional polymerizable compound (B1) is preferably a diacrylate of a 5-mol ethylene oxide adduct of 1,6-hexanediol (5EO-HDDA).

The content of the polymerizable compound (B1) in the varnish composition is preferably 20% by mass or less, more preferably 15% by mass or less, based on the total composition; on the other hand, it is preferably 3% by mass or more, more preferably 4% by mass or more. The content of the polymerizable compound (B1) in the varnish composition is preferably 65% by mass or less, more preferably 55% by mass or less, based on the total of the polymerizable monomers (B); on the other hand, it is preferably 5% by mass or more, more preferably 10% by mass or more. When the polymerizable compound (B1) is at a certain level or more, the flexibility and stretchability of the cured layer of the varnish composition are likely to be increased, and cracking of the printed matter is likely to be suppressed. On the other hand, when the content of the polymerizable compound (B1) is too high, the film peelability of the cured layer in the printed matter is likely to be reduced, and the scratch resistance of the cured layer is also likely to be reduced.

1-2-2. Tri- or higher functional polymerizable compound having an ethylene oxide adduct skeleton of a polyol (B2)
The polymerizable monomer (B) may contain a trifunctional or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol. The trifunctional or higher functional polymerizable compound (B2) is preferably a polyol having three or more alcoholic hydroxyl groups. Specific examples of the polyol of the trifunctional or higher polymerizable compound (B2) include glycerin, propane-1,1,3-triol, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,1,4-butanetriol, 2-(hydroxymethyl)-1,3-propanediol, 2-methylpropane-1,1,1-triol, 2-methyl-1,2,3-propanetriol, trimethylolethane, 2,3,4-pentanetriol, 1,2,3-pentanetriol, 1,2,4-pentanetriol, 1,2,5-pentanetriol, 1,3,4-pentanetriol, and 1,3,5-pentanetriol. 2-methyl-1,2,4-butanetriol, 3-methyl-1,2,3-butanetriol, 2-methylbutane-1,2,3-triol, 2-ethylbutane-1,2,3-triol, 2-(hydroxymethyl)-1,3-butanediol, 2-(hydroxymethyl)-1,4-butanediol, 2-ethyl-1,2,3-propanetriol, trimethylolpropane, 2,4-dihydroxy-3-hydroxymethylpentane, 2-hydroxymethyl-3-methylbutane-1,3-diol, 2-methylpentane-1,3,5-triol, 3-methylpentane-1,3,5-triol, 2-methyl ethylpentane-1,2,3-triol, 3-methylpentane-1,2,5-triol, 1,2,3-hexanetriol, hexane-1,2,4-triol, 1,2,5-hexanetriol, 1,2,6-hexanetriol, 1,3,5-hexanetriol, 1,4,5-hexanetriol, hexane-1,3,6-triol, hexane-2,3,4-triol, 2,2-di(hydroxymethyl)-3-butanol, 3-hydroxymethyl-1,5-pentanediol, 3,3-dimethyl-1,2,4-butanetriol, 2-isopropylpropane-1,2,3-triol, etc. and polyols having four alcoholic hydroxyl groups, such as 1,2,3,4-butanetetraol, 1,1,4,4-butanetetraol, pentaerythritol, 1,1,5,5-pentanetetraol, 1,2,3,5-pentanetetraol, 1,2,4,5-pentanetetraol, 2-methyl-1,2,3,4-butanetetraol, 1,2,4,5-hexanetetraol, 1,2,5,6-hexanetetraol, 2,2-bis(hydroxymethyl)-1,4-butanediol, and 4-methylpentane-1,2,4,5-tetraol. The polyol of the trifunctional or higher polymerizable compound (B2) is preferably trimethylolpropane.

The number of ethylene oxides added to the polyol of the trifunctional or higher polymerizable compound (B2) may be 1 or more, and more preferably 2 or more; on the other hand, it is preferably 12 or less, more preferably 9 or less, and even more preferably 6 or less, and may be 5 or less. If the number of ethylene oxides added to the polyol of the polymerizable compound (B2) is too large, the adhesion of the cured layer may decrease, and the scratch resistance may also decrease.

The trifunctional polymerizable compound (B2) may be a compound obtained by reacting an ethylene oxide adduct of a polyol with a compound having a polymerizable functional group (e.g., a (meth)acryloyl group); preferably, a compound obtained by esterifying an ethylene oxide adduct of a polyol with three (meth)acrylic acids. The (meth)acrylic acid is one or both of acrylic acid and (meth)acrylic acid.

The content of the polymerizable compound (B2) in the varnish composition is preferably 10% by mass or more, more preferably 15% by mass or more, based on the entire composition; on the other hand, it is preferably 30% by mass or less, more preferably 25% by mass or less. The content of the polymerizable compound (B2) in the varnish composition is preferably 30% by mass or more, more preferably 40% by mass or more, based on the entire polymerizable monomer (B); on the other hand, it is preferably 70% by mass or less, more preferably 60% by mass or less. When the content of the polymerizable compound (B2) in the varnish composition is a certain level or more, the curing property of the cured layer of the varnish composition is increased, and the surface hardness is also increased. On the other hand, when the content of the polymerizable compound (B2) in the varnish composition is too high, the flexibility and elasticity of the cured layer of the varnish composition are easily deteriorated, and the printed matter is easily cracked.

1-2-3. Other polymerizable compounds (B3)
The polymerizable monomer (B) may contain "another polymerizable compound (B3)" other than the polymerizable compounds (B1) and (B2). The other polymerizable compound (B3) may have one, two, or three or more polymerizable functional groups, preferably (meth)acryloyl groups. The other polymerizable compound (B3) is preferably liquid at room temperature (25°C) so that the varnish composition becomes a solution.

Examples of the polymerizable compound (B3) having one (meth)acryloyl group include alkyl (meth)acrylates such as methyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as butoxyethyl (meth)acrylate; (meth)acrylic acid esters of polyalkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monobutyl ether, and dipropylene glycol monomethyl ether; (meth)acrylic acid esters of polyalkylene glycol monoaryl ethers such as hexaethylene glycol monophenyl ether; isobornyl (meth)acrylate; glycerol (meth)acrylate; 2-hydroxyethyl (meth)acrylate, and the like.

Examples of the polymerizable compound (B3) having two (meth)acryloyl groups include bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, glycerol di(meth)acrylate, neopentyl glycol di(meth)acrylate, etc.

Examples of the polymerizable compound (B3) having three or more (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc.

At least a portion of the other polymerizable compound (B3) is preferably a polyfunctional polymerizable compound, and more preferably a polymerizable compound having two (meth)acryloyl groups. For example, at least a portion of the polymerizable compound (B3) is preferably tripropylene glycol di(meth)acrylate or 1,6-hexanediol di(meth)acrylate. By making the other polymerizable compound (B3) polyfunctional, the surface hardness of the cured layer of the varnish composition can be increased (scratch resistance can be increased).

1-3. Initiator (C)
The initiator (C) contained in the varnish composition may be any substance that generates radicals when irradiated with active energy rays. The initiator (C) is not particularly limited, but may be broadly classified into a photocleavage type and a hydrogen abstraction type. Specific examples of the initiator (C) include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p,p'-bisdiethylaminobenzophenone, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin n-butyl ether, benzoin dimethyl ketal, thioxanthone, p-isopropyl-α-hydroxyisobutylphenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzophenone, 4-methylbenzophenone, 2,2-dimethoxy-1,2-diphenylethanone, and diphenyl-2,4,6-trimethylbenzoylphosphine oxide. It is preferable to select an initiator (C) that easily absorbs the active energy rays irradiated in the lamicoat process; for example, it is preferable to have a hydroxyalkylphenone structure, such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. In addition, it may be preferable to select an initiator (C) that is easily soluble in the polymerizable monomer (B).

The content of initiator (C) in the varnish composition is preferably 0 to 20% by mass relative to the entire varnish composition. Although the varnish composition has active energy ray curing properties, for example, when it is cured by electron beam, it may be preferable not to include initiator (C). On the other hand, when the varnish composition is cured by ultraviolet ray, the content of initiator (C) relative to the entire varnish composition is 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more. On the other hand, the content of initiator (C) relative to the entire varnish composition is 20% by mass or less, preferably 15% by mass or less.

The initiator (C) can impart curability to the varnish composition. If the content of the initiator (C) in the varnish composition is too low, the curability of the varnish composition is insufficient, and the cured layer in the printed matter tends to become tacky or have poor scratch resistance. In addition, the initiator (C) may function as a plasticizer in the varnish composition and its cured layer. For example, if the content of the initiator (C) in the entire varnish composition is 5% by mass or more, preferably 8% by mass or more, the flexibility and stretchability of the cured layer of the varnish composition are improved, making it easier to suppress cracking of the creases in the printed matter.

1-4. Silicone compounds (D)
The silicone compound (D) contained in the varnish composition can be polysiloxane, modified silicone oil, polysiloxane containing trimethylsiloxysilicate, silicone acrylic resin, etc. The silicone compound (D) can function as wax in the varnish composition, so that the film peelability from the cured layer of the varnish composition is improved.In addition, it is preferable that the silicone compound (D) also functions as a leveling agent.

The content of the silicone-based compound (D) in the varnish composition is 0.1% by mass or more, and more preferably 0.2% by mass or more, based on the total varnish composition; on the other hand, it is 0.5% by mass or less, and preferably 0.4% by mass or less. When the content of the silicone-based compound (D) is a certain level or more, the film peelability is improved, and the surface slipperiness of the cured layer is improved, improving scratch resistance.

1-5. Optional Components The varnish composition may contain, as necessary, an ultraviolet absorber, a light stabilizer, an antioxidant, an antibacterial and antifungal agent, an antistatic agent, a colorant, a lubricant, a filler, a latent curing agent, a flame retardant, a plasticizer, and the like.

Examples of ultraviolet absorbers include organic ultraviolet absorbers such as salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers, and inorganic ultraviolet absorbers made of fine particles of zinc oxide, titanium oxide, and cerium oxide.

Examples of light stabilizers include HALS (hindered amine light stabilizers); specifically, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis1,1-dimethylethyl]-4-hydroxyphenyl]methyl-butylmalonate, and succinic acid dimethyl-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate.

Examples of antibacterial and antifungal agents include silver-based inorganic compounds, binazine, preventol, thiebendazole, benzimidazole, and thiazolyl sulfamide compounds.

Antistatic agents include positive ion types such as alkylamine sulfate type, quaternary ammonium salt type, and pyridinium salt type, and amphoteric ion types such as alkylbetaine type and alkylimidazoline type. Quaternary ammonium salt type is particularly preferred, and examples of such types include low molecular weight surfactants and acrylate copolymers containing quaternary ammonium bases.

The varnish composition may contain no solvent (organic solvent and water) or may contain a small amount of solvent (e.g., 5% by mass or less, 3% by mass or less, and preferably 1% by mass or less, based on the total amount of the varnish composition).

2. Preparation of printed matter by lamicoating The active energy ray-curable varnish composition of the present invention can be used for preparing printed matter by lamicoating. The process for preparing printed matter by lamicoating comprises at least the following steps A to D.
(Step A) The active energy ray-curable varnish composition of the present invention is applied onto the surface of a substrate to form a coating layer.
(Step B) A polyolefin film is superimposed and adhered onto the coating layer of the active energy ray-curable varnish composition to form a laminate.
(Step C) The laminate is irradiated with active energy rays from the polyolefin film side to cure the coating layer to form a cured layer.
(Step D) The polyolefin film is peeled off from the cured layer to obtain a printed matter (laminate).

The substrate in (Step A) may be a paper substrate, a film substrate, a metal substrate, etc., but is preferably a paper substrate or a film substrate. The paper substrate is not particularly limited, but may be UF coated paper, coated cardboard, art paper, polyethylene coated paper, matte coated paper, etc. The substrate may be plain or have a pattern layer made of printing ink.

The method for applying the active energy ray-curable varnish composition is not particularly limited, but in addition to flexographic printing, known methods such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, kiss coating, dip coating, silk screen coating, wire bar coating, flow coating, comma coating, pouring coating, and spray coating can be applied. Methods that do not require solvent dilution are preferred. The amount of active energy ray-curable varnish composition applied to a substrate is preferably such that the thickness of the coating layer is about 3 μm to 10 μm, but may be set according to the application of the printed matter.

The material of the polyolefin film in (step B) may be a polyolefin such as polyethylene or polypropylene. The polyolefin film is capable of transmitting the active energy rays irradiated in (step C). The surface of the polyolefin film (the surface in contact with the coating layer made of the active energy ray-curable varnish composition) may have a surface shape such as a flat pattern, a hologram pattern, an embossed pattern, or the like. The surface shape can be transferred to the coating film to impart cosmetic properties to the cured layer. A known laminator or the like can be used to bond the polyolefin film to the coating film for adhesion.

In step B, it is preferable that the surface of the polyolefin film (the surface that comes into contact with the coating layer made of the active energy ray-curable varnish composition) has not been treated to make it easy to adhere.

In (step C), the laminate is irradiated with active energy rays to cure the coating layer made of the active energy ray curable varnish composition. At this time, the active energy rays are irradiated to the coating layer made of the active energy ray curable varnish composition through the polyolefin film. However, if the substrate can transmit the active energy rays, the active energy rays may be irradiated to the coating layer made of the active energy ray curable varnish composition through the substrate. The active energy rays to be irradiated are a general term for ionizing radiation and electromagnetic waves such as electron beams, ultraviolet rays, or gamma rays, and are preferably ultraviolet rays. When curing with ultraviolet rays, it is preferable to cure the coating layer with an accumulated light amount of 50 mJ/cm ² or more. If the accumulated light amount is insufficient, the coating layer may not be cured properly due to poor curing.

In (step D), the polyolefin film is peeled off from the cured layer. By peeling off the polyolefin film, a cured layer is obtained to which the surface shape of the polyolefin film has been transferred. The peeled off polyolefin film can be reused by repeatedly using it in the lami-coat process.

After peeling off the polyolefin film, the surface of the cured layer may be subjected to surface treatment such as making it highly glossy, thereby further improving the quality of the resulting print.

The present invention will be described in more detail below with reference to examples, but the scope of the present invention should not be interpreted as being limited by the description of the examples. The compounding amounts shown in the table are in parts by mass.

A. Preparation of active energy ray curable varnish composition The components used in the preparation of the active energy ray curable varnish composition are shown below. The active energy ray curable varnish compositions of Examples 1 to 7 and Comparative Examples 1 to 5 were prepared by mixing the components according to the formulation shown in Table 1.

(Resin varnish)
VS-1063 Varnish: A varnish obtained by dissolving VS-1063 in the same mass of HDDA (1,6-hexanediol diacrylate). VS-1063 is a styrene homopolymer (Mw=5,500, manufactured by Seiko PMC Corporation).
US-1071 Varnish: A varnish obtained by dissolving US-1071 in the same mass of HDDA. US-1071 is an acid group-containing polystyrene (Mw=10,000, acid value 75 mgKOH/g, manufactured by Seiko PMC Corporation).
BS261 varnish: a varnish obtained by dissolving BS261 in the same mass of HDDA. BS261 is an acrylic resin (product name "Beamset 261", manufactured by Arakawa Chemical Industries, Ltd.).

(Polymerizable monomer)
5EO-HDDA: Diacrylate of 1,6-hexanediol 5 moles EO adduct 3EO-TMPTA: Triacrylate of trimethylolpropane 3 moles EO adduct 6EO-TMPTA: Triacrylate of trimethylolpropane 6 moles EO adduct 9EO-TMPTA: Triacrylate of trimethylolpropane 9 moles EO adduct TPGDA: Tripropylene glycol diacrylate HDDA: 1,6-hexanediol diacrylate EOEOEA: 2-(2-ethoxyethoxy)ethyl acrylate

(Additives)
Initiator: 1-hydroxycyclohexyl phenyl ketone (product name "Omnirad 184", manufactured by IGM Resins B.V.)
1711EF: (product name "Disparlon 1711EF", polyether modified silicone compound, solid content 50% by mass, manufactured by Kusumoto Chemicals Co., Ltd.)

B. Preparation of printed matter by lamicoat processing Using any of the active energy ray curable varnish compositions of Examples 1 to 7 and Comparative Examples 1 to 5 shown in Table 1, printed matter was prepared by lamicoat processing as shown in FIG. 1. First, one side of a paper substrate (10) made of UF coated paper (manufactured by Oji Materia Co., Ltd.) and one side of a polypropylene film (P-2161, thickness 30 μm, manufactured by Toyobo Co., Ltd.) (11) were fixed (upper left end in the figure). Next, 1.0 gram of active energy ray curable varnish composition (12) was dripped onto the surface of the paper substrate (10). Next, the polypropylene film (11) was sandwiched between a first mere bar (diameter 0.1 mm) (13) and a second mere bar (diameter 0.1 mm) (14), and the first mere bar (13) and the second mere bar (14) were simultaneously bar drawn. Thereby, the first mear bar (13) spreads the active energy ray curable varnish composition (12) on the surface of the paper substrate (10), while the second mear bar (14) presses the polypropylene film (11) against the spread active energy ray curable composition layer to adhere it closely. As a result, a laminate of the paper substrate (10), the coating layer of the active energy ray curable varnish composition (12), and the polypropylene film (11) was obtained. The coating layer of the active energy ray curable varnish composition (12) was about 10 μm thick.

Thereafter, the obtained laminate was irradiated with ultraviolet light from the polypropylene film (11) side using a conveyor-type ultraviolet light irradiation device equipped with a high-pressure mercury lamp. The laminate (displayed product) was passed once with the moving speed of the irradiation device set to 40 m/min and the irradiation intensity ^set to 120 W/cm2. After the ultraviolet light irradiation, the polypropylene film (11) was peeled off to prepare a print for evaluation.

C. Evaluation of Printed Matter The obtained printed matter was used to evaluate curability, peelability, adhesion, scratch resistance, gloss, sliding angle, blocking resistance, and crease cracking.

(Curing property) The curing property of the obtained print (immediately after production) was evaluated based on the presence or absence of tackiness on the surface of the cured layer. The presence or absence of tackiness was judged by whether or not the surface of the cured layer felt sticky when touched with a finger.
○: No tack ×: Tack

(Removability) When producing a printed matter, when the polypropylene film was peeled off, it was confirmed whether or not a cured layer made of the active energy ray-curable varnish composition adhered to the peeled off polypropylene film.
○: No adhesion was observed ×: Adhesion was observed

(Adhesion) Immediately after production and after being left at room temperature for 24 hours after production, the cellophane tape attached to the surface of the cured layer of the obtained print was peeled off, and the state of the cured layer was visually observed to evaluate adhesion. The evaluation results are shown in the columns "Adhesion immediately after" and "Adhesion after 24 hours" in Table 1. (Evaluation of "△ to ◯" means that there were cases where it was evaluated as ◯ and cases where it was evaluated as △.)
○: No peeling occurred between the paper substrate and the cured layer, or the paper substrate peeled off. △: Slight peeling occurred between the paper substrate and the cured layer. ×: Most of the paper substrate and the cured layer peeled off.

(Scratch Resistance) The surface of the cured layer of the printed matter (immediately after production) was scratched with a fingernail, and the scratch resistance was evaluated by visually checking whether or not scratches were formed.
◯: No scratches were observed △: Slight scratches were observed ×: Clear scratches were observed

(Gloss) The 60° reflected gloss value (unit: GU, gloss unit) of the surface of the cured layer of the resulting print (immediately after production) was measured using a Murakami digital gloss meter (manufactured by Murakami Color Laboratory). The results are shown in Table 1.

(Slip angle) The slip angle (unit: °) of the surface of the cured layer of the obtained print (immediately after production) was measured using a slip angle tester manufactured by Toyo Seiki Co., Ltd. under environmental conditions of an ambient temperature of 23°C and a humidity of 50%.

(Blocking resistance) The obtained printed matter (immediately after production) was placed in contact with the cured layers of the printed matter facing each other, and left for 24 hours under a load of 1 kg in an environment of 50° C. and 80% RH. After that, the blocking resistance was evaluated by visually checking whether there was peeling resistance when the contact was released and whether the cured layers peeled off.
◯: No peeling resistance, and peeling of the cured material layer was not observed. Δ: Peeling resistance was observed, but peeling of the cured material layer was not observed. ×: Peeling of the cured material layer was observed.

(Creasing of Crease Lines (Flexibility)) The resulting print (immediately after curing) was folded 180° and evaluated according to the following evaluation criteria.
◯: No crease or fine cracks were generated in the cured layer when folded. △: Fine cracks were generated in the cured layer when folded. ×: Creases were generated in the cured layer when folded.

As shown in Comparative Examples 1 to 3, prints obtained using a varnish composition that does not contain 5EO-HDDA, a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol, exhibit cracked lines and poor flexibility. Furthermore, as can be seen from Comparative Example 3, when EOEOEA (2-(2-ethoxyethoxy)ethyl acrylate), a monofunctional polymerizable compound, is added instead of 5EO-HDDA, scratch resistance is also reduced.

As shown in Comparative Example 4, the print obtained using a varnish composition containing an acrylic resin but not a polystyrene resin had poor peelability and reduced scratch resistance. Also, as shown in Comparative Example 5, the print obtained using a varnish composition containing a styrene resin containing an acid group had reduced adhesion and scratch resistance. Thus, it can be seen that the incorporation of a styrene homopolymer (a styrene resin with a high styrene content) increases scratch resistance and improves peelability and adhesion.

In contrast, as shown in Examples 1 to 7, prints obtained using a varnish composition containing styrene homopolymer and 5EO-HDDA, a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol, have sufficient peelability, adhesion, scratch resistance, gloss (leveling ability), and flexibility.

In addition, as shown in Examples 3 to 5, when the content of 5EO-HDDA, a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol, is in the range of approximately 5 to 20 mass % relative to the total composition, it is found that a printed matter having sufficient peelability, adhesion, scratch resistance, gloss (leveling ability), and flexibility is formed.

As shown in Examples 3, 6 and 7, the curability of the cured layer is sufficiently improved by blending 3EO-TMPTA, 6EO-TMPTA and 9EO-TMPTA, which are trifunctional polymerizable compounds (B2) having an ethylene oxide adduct skeleton of a polyol. However, as the number of ethylene oxide adducts in the polymerizable compound (B2) increases, the adhesion tends to decrease and the scratch resistance also tends to decrease.

Furthermore, as shown in Examples 1 to 3, it can be seen that the adhesion and flexibility can be further improved by adjusting the content of the initiator. The reason for this improvement in adhesion and flexibility is not limited, but it is thought that this is because the initiator functions as a plasticizer in the varnish composition or the cured product layer, or because an increase in the polymerization terminals reduces the molecular weight (degree of polymerization) of the cured product, resulting in flexible physical properties.

The active energy ray curable varnish composition of the present invention is used to create printed matter by lami-coating (LC processing), and can improve the quality of the printed matter. The quality of the printed matter means that the cured material layer of the varnish composition has high adhesion, the (surface) hardness of the cured material layer is high (scratch resistance, etc.), the gloss of the cured material layer is high (sufficient leveling), the surface of the cured material layer has high slipperiness, no blocking occurs even when the cured material layers are in contact with each other, and the cured material layer has high flexibility and stretchability (suppression of cracking of creases). Therefore, it further expands the range of applications for creating printed matter by lami-coating, and contributes to the expansion of the market for lami-coating.

10 Paper substrate 11 Polypropylene film 12 Varnish composition 13 First mere bar 14 Second mere bar

Claims (13)

The active energy ray-curable varnish composition is for a laminate obtained by overlaying a polyolefin film on a coating layer made of an active energy ray-curable varnish composition formed on a substrate, curing the coating layer by irradiation with active energy rays to form a cured material layer, and peeling the polyolefin film from the cured material layer,
An active energy ray-curable varnish composition comprising the following (1) to (4):
(1) A styrene-based resin (A) of 10.0 to 40.0% by mass relative to the entire composition, the mass ratio of styrene being 95% or more and the acid value being 0 mgKOH/g or 0 to 10 mgKOH/g;
(2) a polymerizable monomer (B) containing a bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol;
(3) 0.1 to 20.0% by mass of an initiator (C) based on the total mass of the composition;
(4) 0.1 to 0.5 mass % of a silicone-based compound (D) based on the total mass of the composition. The active energy ray-curable varnish composition according to claim 1, wherein the styrene-based resin (A) is a styrene homopolymer. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the styrene-based resin (A) has a mass average molecular weight of 3,000 to 8,000. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the polyol of the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of the polyol is a polyol having 4 to 8 carbon atoms. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the number of ethylene oxide additions in the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of the polyol is 3 to 8. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of a polyol is a diacrylate of a 5-mol ethylene oxide adduct of 1,6-hexanediol (5EO-HDDA). The active energy ray-curable varnish composition according to claim 1 or 2, wherein the content of the bifunctional polymerizable compound (B1) having an ethylene oxide adduct skeleton of the polyol is 20.0 mass% or less based on the total composition. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the initiator (C) has a hydroxyalkylphenone structure. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the content of the initiator (C) is 8.0 mass% or more based on the total composition. The active energy ray-curable varnish composition according to claim 1 or 2, wherein the polymerizable monomer (B) further contains a trifunctional or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol. The active energy ray-curable varnish composition according to claim 10, wherein the polyol of the trifunctional or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of the polyol is trimethylolpropane. The active energy ray-curable varnish composition according to claim 10, wherein the number of ethylene oxide additions in the trifunctional or higher polymerizable compound (B2) having an ethylene oxide adduct skeleton of a polyol is 1 to 12. The active energy ray-curable varnish composition according to claim 10, wherein the content of the trifunctional or higher functional polymerizable compound (B2) having an ethylene oxide adduct skeleton of the polyol is 10.0 to 30.0 mass% based on the total composition.