JP7025288B2 - Printed matter - Google Patents

Description

The present invention relates to a printed matter obtained by laminating an ink layer made of an active energy ray-curable ink and a surface protection layer on a substrate.

Conventionally, a printing method using an inkjet printer has been used to decorate a base material such as plastic or a building board. In the decoration by an inkjet printer, ink may be printed directly on the base material, but it is also widely used to provide an ink receiving layer on the base material and perform printing on the ink receiving layer. In recent years, attention has been paid to active energy ray-curable inks having a short curing time and excellent productivity, and printing systems using active energy ray-curable inks have been developed.

The printed matter decorated with such an active energy ray-curable ink may be accompanied by a peculiar odor in a short period after production, and it is required to reduce the odor of the ink or the printed matter. In particular, reducing the amount of monomer emitted from the ink used has been an issue. Patent Document 1 discloses an ink in which the odor of the monomer is reduced by adjusting the content of the monomer and the photopolymerization initiator contained in the ink. Patent Document 2 discloses that a monomer odor is suppressed by providing an ozone generating means in the ink coating unit.

Japanese Unexamined Patent Publication No. 2005-154537 Japanese Unexamined Patent Publication No. 2010-208042

When printing with active energy ray-curable ink, the monomer in the active energy ray-curable ink remains in the ink layer in an uncured state, and the unreacted monomer is emitted from the decorated product. There is. In particular, when printing is performed on an absorbent substrate or an ink receiving layer, the monomer in the active energy ray-curable ink tends to remain not only in the ink layer but also in the receiving layer in an uncured state. , Many unreacted monomers are easily released from the decorated product.

Further, from the viewpoint of active energy ray-curable ink, as a method of reducing the amount of unreacted monomer after ink curing, there are a method of adjusting the content of the monomer and the photopolymerization initiator and a method of increasing the irradiation energy amount. These methods use an excessive amount of photopolymerization initiator and require an excessive amount of irradiation energy, which is wasteful and may deteriorate the film properties such as weather resistance and color development of the ink film in some cases. There is also. Further, in the case of printing the active energy ray-curable ink on the absorbent substrate or the ink receiving layer, these methods alone are not sufficient to reduce the amount of unreacted monomers remaining in the receiving layer.

Further, although there is a method of using a monomer having a low odor, it may be difficult to sufficiently satisfy the film characteristics such as weather resistance and color development of the ink film because the design width of the ink cannot be sufficiently obtained. Further, a method of providing an ozone generating means in the ink coating unit is also disclosed, but there is a concern that it may lead to an increase in the cost of manufacturing equipment.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a printed matter in which an amount of unreacted monomer emitted from a printed matter using an active energy ray-curable ink is small.

The present inventors have found that the object of the present invention is achieved by the following.

(1) A printed matter having an ink layer made of an active energy ray-curable ink containing a polymerizable compound on a substrate and a surface protective layer laminated on the ink layer, and is a monomer of the ink layer. A printed matter having a emission rate of 10.0 μg / m ² · h or less and a monomer emission rate of 1.0 μg / m ² · h or less after laminating the surface protective layer.
(2) The ink layer is a polymer containing 25 to 85% by mass of at least one structural unit derived from an ethylenically unsaturated monomer having a solubility parameter (hereinafter, also referred to as SP value) of 9.50 to 13.0. The printed matter according to 1 above, which is provided on the ink receiving layer containing the above 1.
(3) The printed matter according to 1 or 2 above, wherein the proportion of the monofunctional monomer contained in the polymerizable compound is 50% by mass or more.
(4) Absolute difference between the mass average value of the SP value of the ethylenically unsaturated monomer forming the ink layer and the SP value of the organic solvent component contained in the surface protective layer forming composition forming the surface protective layer in the previous period. Printed matter with a value of 0.70 or less.

According to the present invention, it is possible to provide a printed matter using an active energy ray-curable ink with less emission of unreacted monomers from the printed matter.

Hereinafter, embodiments of the present invention will be described in detail.
<Printed matter>
The printed matter of the present invention is a printed matter obtained by having an ink layer made of an active energy ray-curable ink containing a polymerizable compound on a substrate and laminating a surface protective layer on the ink layer. The layer has a monomer emission rate of 10.0 μg / m ² · h or less, and the monomer emission rate after laminating the surface protective layer is 1.0 μg / m ² · h or less.

≪Monomer emission rate≫
In the present invention, the monomer emission rate of the ink layer is 10.0 μg / m ² · h or less, and the monomer emission rate after the surface protective layer is provided is 1.0 μg / m ² · h or less. Even if the monomer diffusion rate of the ink layer of the present invention is 10.0 μg / m ² · h, a surface protective layer is provided, and the mass average value of the SP value of the monomer contained in the ink layer and the surface protective layer forming composition. By setting the absolute value of the difference from the SP value of the organic solvent component contained therein to 0.70 or less, the monomer emission rate can be achieved to be 1.0 μg / m ² · h or less. Especially when the ink receiving layer is used, the effect is remarkable.

≪Ink layer≫
The ink layer of the present invention is formed by printing an active energy ray-curable ink on an ink receiving layer described later by a printing means such as printing with an inkjet printer (that is, an inkjet method) and then curing the ink. be able to. The thickness of the ink layer is not particularly limited, and is, for example, 5 to 50 μm.

Examples of the active energy ray used for curing in the present invention include a metal halide lamp, a high-pressure mercury lamp, and an ultraviolet LED, and the wavelength of the activated energy ray to be irradiated overlaps with the absorption wavelength of the photopolymerization initiator. It is preferable that the main wavelength of the active energy ray is 360 to 425 nm.

≪Ink receiving layer≫
In the present invention, an ink layer made of an active energy ray-curable ink containing a polymerizable compound may be directly formed on the base material, but from the viewpoint of adhesion between the base material and the ink layer and color development of the ink layer. , It is preferable to provide an ink receiving layer.

The ink receiving layer of the present invention can be formed by applying a paint for an ink receiving layer to the surface of a base material and then forming a film by drying or the like.

The paint for an ink receiving layer of the present invention contains an aqueous dispersion of resin particles containing a resin, and in this resin, the ratio of structural units derived from a monomer having a cyclic structure is more than 0 and 28% by mass or less. It is preferably used.

The resin is not particularly limited, and is, for example, a polymer containing a structural unit derived from a monomer having no cyclic structure, a polymer containing a structural unit derived from a monomer having no cyclic structure, and a structural unit derived from a monomer having a cyclic structure. Can be mentioned. Each of the structural unit derived from the monomer having no cyclic structure and the structural unit derived from the monomer having a cyclic structure may be used alone or in combination of two or more.

Examples of the monomer having a cyclic structure include an alicyclic group-containing unsaturated hydrocarbon, an aromatic ring-containing unsaturated hydrocarbon, an alicyclic group-containing unsaturated carboxylic acid, an alicyclic group-containing unsaturated carboxylic acid ester, and a fat. Cyclic group-containing unsaturated carboxylic acid amide, aromatic ring-containing unsaturated carboxylic acid, aromatic ring-containing unsaturated carboxylic acid ester, aromatic ring-containing unsaturated carboxylic acid amide, alicyclic group-containing alkoxysilane, aromatic ring-containing alkoxysilane, etc. Can be mentioned. The alicyclic group and the aromatic ring may have a hetero atom such as a nitrogen atom or an oxygen atom in the ring, or may have a substituent.

The alicyclic group is not particularly limited, and is, for example, an alicyclic hydrocarbon group such as a cycloalkyl group (for example, a cyclohexyl group) or a cycloalkenyl group (for example, a cyclohexenyl group); an alicyclic group such as a piperidyl group. The formula heterocyclic group can be mentioned. The aromatic ring is not particularly limited, and examples thereof include an aromatic carbocycle such as a benzene ring, a naphthalene ring, and an anthracene ring; and an aromatic heterocycle such as a pyridine ring.

Specific examples of the alicyclic group-containing unsaturated hydrocarbon include vinylcyclohexane and the like. Specific examples of the aromatic ring-containing unsaturated hydrocarbon include styrene and the like. Specific examples of the alicyclic group-containing unsaturated carboxylic acid include 3-cyclohexylacrylic acid. Specific examples of the alicyclic group-containing unsaturated carboxylic acid ester include cyclohexyl (meth) acrylate, glycidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and the like.

Specific examples of the alicyclic group-containing unsaturated carboxylic acid amide include N-cyclohexyl (meth) acrylamide and the like. Specific examples of the aromatic ring-containing unsaturated carboxylic acid include 3-phenyl (meth) acrylic acid. Specific examples of the aromatic ring-containing unsaturated carboxylic acid ester include phenyl (meth) acrylate and the like. Specific examples of the aromatic ring-containing unsaturated carboxylic acid amide include N-phenyl (meth) acrylamide and the like. Specific examples of the alicyclic group-containing alkoxysilane include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane.

Specific examples of the aromatic ring-containing alkoxysilane include 3-phenoxypropyltrimethoxysilane and 3-phenoxypropyltriethoxysilane. From the viewpoint of color development of the ink receiving layer, cyclohexylmethacrylate, styrene, glycidylmethacrylate, 3-glycidoxypropyltriethoxysilane, 1,2,2,6,6-pentamethyl-4-piperidylmethacrylate and the like are preferable.

The monomer having no cyclic structure is not particularly limited, and is, for example, a linear or branched unsaturated hydrocarbon, a linear or branched unsaturated carboxylic acid, or a linear or branched unsaturated carboxylic acid. Examples thereof include acid esters, linear or branched unsaturated carboxylic acid amides, and the like. Specific examples of linear or branched unsaturated hydrocarbons include ethylene and propylene. Specific examples of the linear or branched unsaturated carboxylic acid include (meth) acrylic acid.

Specific examples of the linear or branched unsaturated carboxylic acid ester include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Alkenyl (meth) acrylates such as allyl (meth) acrylates; 3- (meth) acryloyloxypropyltrialkoxysilanes such as 3- (meth) acryloyloxypropyltrimethoxysilane and 3- (meth) acryloyloxypropyltriethoxysilane. And so on. Specific examples of the linear or branched unsaturated carboxylic acid amide include diacetone (meth) acrylamide and the like.

As the monomer having no cyclic structure, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, methacrylic acid, diacetone acrylamide, 3-methacryloyloxypropyltrimethoxysilane and allyl methacrylate are preferable.

In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid, (meth) acrylate means acrylate or methacrylate, and (meth) acrylamide means acrylamide or methacrylamide. means.

In the above resin, the ratio of the structural unit derived from the monomer having a cyclic structure is more than 0 and 28% by mass or less, preferably 0.01 to 26% by mass, and more preferably 0.1 to 25% by mass. The slight presence of the monomer having a cyclic structure can be expected to be effective in adjusting the dot diameter.

The resin is a polymer containing at least one structural unit derived from an ethylenically unsaturated monomer having a solubility parameter of 9.50 to 13.0, preferably 25 to 85% by mass.
In the present specification, the ethylenically unsaturated monomer means a monomer having a double bond in the molecule and causing a polymerization reaction through addition to the double bond. The ethylenically unsaturated monomer is not particularly limited, and examples thereof include those having a double bond among those exemplified above as a monomer having no cyclic structure and a monomer having a cyclic structure.

The calculated glass transition temperature of the resin is preferably −15 to 85 ° C., more preferably −10 to 50 ° C., and even more preferably −5 to 40 ° C. from the viewpoint of reducing unreacted monomers. be. When the calculated glass transition temperature is −15 ° C. or higher, the sticky feeling is unlikely to remain after drying.
When the calculated glass transition temperature is 85 ° C. or lower, drying is unlikely to be delayed. In the present specification, the calculated glass transition temperature means the glass transition temperature calculated by the Fox formula.

The method for producing an aqueous dispersion of resin particles containing the resin has, for example, according to a conventional method, a monomer having no cyclic structure, a monomer having no cyclic structure, and a cyclic structure in an aqueous medium containing water as a main component. It can be produced by subjecting it to a combination with a monomer or the like for emulsion polymerization.

The content of the resin is preferably 10 to 60% by mass, more preferably 20 to 45% by mass, based on the components forming the ink receiving layer. When the content is 10 to 60% by mass, the monomer is unlikely to remain after the printing, and the ink receiving layer and the ink layer or the ink receiving layer and the surface protective layer while maintaining the performance excellent in color development. It is possible to increase the adhesiveness of the ink.

The paint for an ink receiving layer according to the present invention may contain a pigment in addition to the above-mentioned aqueous dispersion. The pigment is not particularly limited, and examples thereof include a coloring pigment (for example, a white pigment), a rust preventive pigment, and an extender pigment generally used in the coating industry.

Specific examples of coloring pigments, rust preventive pigments, and extender pigments include titanium oxide, red iron oxide, yellow iron oxide, carbon black, aluminum tripolyphosphate, zinc phosphate, condensed aluminum phosphate, barium metaborate, calcium carbonate, and sulfuric acid. Inorganic pigments such as barium, kaolin, talc, clay, mica, alumina, myoban, white clay, magnesium hydroxide, and magnesium oxide, phthalocyanine blue, phthalocyanine green, naphthol red, quinacridon red, benzimidazolone yellow, Hansa yellow, benz Examples thereof include organic pigments such as imidazolone orange and dioxazine violet. The pigment may be used alone or in combination of two or more.

The content of the pigment is preferably 35 to 85% by mass, more preferably 40 to 75% by mass, based on the components forming the ink receiving layer. When the content is 35 to 85% by mass, the monomer is unlikely to remain after the printing, and the ink receiving layer and the ink layer or the ink receiving layer and the surface protective layer while maintaining the performance excellent in color development. It is possible to increase the adhesiveness of the ink.

The paint for an ink receiving layer according to the present invention may further contain a film forming aid. From the viewpoint of film forming property, the content of the film forming aid is preferably 0 to 10% by mass with respect to the paint.

In addition to the above-mentioned components, the paint for an ink receiving layer according to the present invention includes additives commonly used in the paint industry, such as photopolymerization initiators, photostabilizers, polymerization inhibitors, organic solvents, and antioxidants. , Silane coupling agent, plasticizer, defoaming agent, surface conditioner, wet dispersant, rheology control agent, ultraviolet absorber, viscosity adjuster, preservative, etc. are appropriately selected within a range that does not impair the object of the present invention. May be blended.

The ink absorption rate of the coating film made of the dried product of the ink receiving layer coating material according to the present invention is 100% or less, preferably 90% or less, and more preferably 85% or less. When the ink absorption rate is 100% or less, the amount of the monomer in the active energy ray-curable ink remaining in the receiving layer in an uncured state can be reduced, and the odor from the decorated product provided with the receiving layer can be reduced. Can be effectively suppressed. In the present specification, the ink absorption rate means an amount measured by the method described in the examples.

Further, the toughness of the coating film tends to be obtained by adjusting the elongation rate of the coating film made of the dried product of the ink receiving layer coating material according to the present invention to 10% or more. The elongation rate of the coating film can be adjusted by adjusting the intermolecular crosslink density of the resin described later and the content of the pigment.

In the resin particles in the paint for an ink receiving layer according to the present invention, it is preferable that crosslinks are present between the molecules of the resin. When crosslinks are present between the molecules of the resin, (1) the higher the crosslink density, the more the permeation of the active energy ray-curable ink into the ink receiving layer is suppressed, so that the monomers in the ink are accepted in an uncured state. It is easy to reduce the amount remaining in the layer, it is possible to effectively suppress the generation of odor from the decorated product provided with the receiving layer, and (2) the ink receiving layer for the above-mentioned monomers and solvents can be effectively suppressed. Dissolution resistance is likely to improve.

Cross-linking between molecules of the resin can be performed by using a cross-linking monomer as a raw material monomer for producing the resin, for example, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, glycidylmethacrylate, allyl. It can be introduced by using methacrylate or the like in combination. For example, epoxy groups react with carboxyl groups such as acrylic acid and methacrylic acid. The crosslinkable monomer used for introducing the crosslink between the molecules of the resin may be used alone or in combination of two or more.

In the paint for an ink receiving layer according to the present invention, it is preferable that crosslinks are present between the particles. When crosslinks are present between the particles, the higher the crosslink density, the more the permeation of the active energy ray-curable ink into the ink receiving layer is suppressed, so that the monomers in the ink remain in the receiving layer in an uncured state. It is easy to reduce the amount, and it is possible to effectively suppress the generation of odor from the decorated product provided with the receiving layer.

Crosslinking between the particles can be introduced by using a crosslinkable monomer such as diacetoneacrylamide or N- (butoxymethyl) acrylamide in combination as a raw material monomer for producing the resin.

Examples of the cross-linking between particles include those introduced via a cross-linking agent such as a compound having an oxazoline group and adipic acid dihydrazide, and those introduced by self-cross-linking between resins. When a compound having an oxazoline group is used, the carboxyl group in the resin participates in the cross-linking reaction. When adipic acid dihydrazide is used, the carbonyl group in the resin participates in the cross-linking reaction.

When N- (butoxymethyl) acrylamide is contained in the raw material monomer, the butoxy group is eliminated by heating to generate a methylol group, and then the resins existing on different particles are self-crosslinked. Each of the cross-linking monomer and the cross-linking agent used for introducing the cross-linking between the particles may be used alone or in combination of two or more.

≪Active energy ray curable ink≫
The active energy ray-curable ink of the present invention contains a coloring pigment. Known materials can be used as the coloring pigment, for example, carbon black, yellow iron oxide, petals, composite oxides (nickel-titanium-based, chromium-titanium-based, bismuth-vanadium-based, cobalt-aluminum-based, cobalt-. Inorganic pigments such as aluminum / chromium-based, ultramarine blue), titanium oxide, quinacridone-based, diketopyrrolopyrrole-based, benzimidazolone-based, isoindolinone-based, anthrapyrimidine-based, phthalocyanine-based, slene-based, dioxazine-based, Examples thereof include organic pigments such as azo. From the viewpoint of weather resistance, it is preferable to use an inorganic pigment.

The content of the coloring pigment in the ink is not particularly limited. The content is preferably 2 to 20% by mass from the viewpoint of color development of the ink.

The ink preferably contains a dispersant. As the dispersant, an anionic dispersant, a cationic dispersant and a nonionic dispersant are preferable. As the dispersant, a commercially available product can be preferably used.

≪Polymerizable compound≫
The active energy ray-curable ink of the present invention contains a polymerizable compound such as an active energy ray-polymerizable monomer. The active energy ray-polymerizable monomer is a monomer that undergoes a polymerization reaction when irradiated with an active energy ray such as ultraviolet rays. Those having a vinyl group are suitable.
The cured product obtained after the polymerization of a polymerizable compound such as an active energy ray-polymerizable monomer functions as a binder.

The polymerizable compound of the present invention is characterized by having a glass transition temperature (hereinafter, also abbreviated as Tg) of −35 to 35 ° C. By using this Tg polymerizable compound, an ink layer having excellent adhesion to the receiving layer is formed even when a receiving layer in which the monomer contained in the active energy ray-curable ink does not easily penetrate is used. be able to.
As the active energy ray-polymerizable monomer, a monofunctional monomer having 1 functional group, a bifunctional monomer having 2 functional groups, and a polyfunctional monomer having 3 or more functional groups can be used.

Among the above active energy ray-polymerizable monomers, the monofunctional monomer preferably has a molecular weight of 1000 or less, and specific examples thereof include acryloylmorpholine, stearyl acrylate, tridecyl acrylate, lauryl acrylate, decyl acrylate, and isodecyl acrylate. , Octyl acrylate, isooctyl acrylate, N, N-dimethylacrylamide, 2-phenoxyethyl acrylate, isobornyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, cyclohexyl acrylate, isoamyl acrylate, 2-Ethylhexyl-diglycol acrylate, EO (ethylene oxide) modified 2-ethylhexyl acrylate, neopentyl glycol acrylic acid benzoic acid ester, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, N-vinylimidazole, tetrahydrofurfuryl acrylate, Examples thereof include methoxydipropylene glycol acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate, cyclic trimethylolpropaneformal acrylate, ethoxy-diethylene glycol acrylate, 4-hydroxybutyl acrylate and the like. .. These monofunctional monomers may be used alone or in combination of two or more.

Among the above active energy ray-polymerizable monomers, the bifunctional monomer preferably has a molecular weight of 1000 or less, and specific examples thereof include 1,10-decanediol diacrylate and 2-methyl-1,8-octanediol. Diacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,9-nonanediol diacrylate, 1,8-octanediol diacrylate, 1,7-heptanediol diacrylate, polytetramethylene Glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate, tripropylene glycol diacrylate, 1,4 -Butanediol diacrylate, dipropylene glycol diacrylate and the like can be mentioned. These bifunctional monomers may be used alone or in combination of two or more.

Among the above active energy ray-polymerizable monomers, the trifunctional or higher functional polyfunctional monomer preferably has a molecular weight of 2000 or less, and specific examples thereof include trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxy. Trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated glycerin triacrylate, tetramethylolmethane triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, EO-modified diglycerin tetraacrylate, ditrimethylolpropane tetraacrylate, di Examples thereof include pentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. In addition, these polyfunctional monomers may be used individually by 1 type, and may be used in combination of 2 or more types.

In the above ink, the content of the active energy ray-polymerizable monomer is preferably 1 to 95% by mass, more preferably 70 to 95% by mass, from the viewpoint of reactivity. Further, from the viewpoint of reducing the residual monomer, the content of the monofunctional monomer is preferably 20 to 85% by mass, more preferably 50 to 85% by mass.

The above ink may use an acrylate oligomer. The acrylate oligomer is an oligomer having one or more acryloyloxy groups (CH ₂ = CHCOO−), and the number of functional groups is preferably 2 to 6. The acrylate oligomer preferably has a molecular weight of 2000 to 20000. The molecular weight is a polystyrene-equivalent weight average molecular weight.

Specific examples of the acrylate oligomer include an amino acrylate oligomer [an acrylate oligomer having a plurality of amino groups (-NH ₂ )], a urethane acrylate oligomer [an acrylate oligomer having a plurality of urethane bonds (-NHCOO-)], and an epoxy acrylate oligomer [epoxy compound]. Acrylate having a plurality of epoxy acrylates obtained by reacting with acrylic acid], a silicone acrylate oligomer [an acrylate oligomer having a plurality of siloxane bonds (-SiO-)], and an ester acrylate oligomer [an acrylate having a plurality of ester bonds (-COO-)]. Acrylate] and butadiene acrylate oligomer [acrylate oligomer having a plurality of butadiene units] and the like. In the above ink, the content of the acrylate oligomer is, for example, 0.4 to 20.0% by mass.

It is preferable to add a photopolymerization initiator, a light stabilizer, a polymerization inhibitor and the like to the ink, and further, in addition to the above-mentioned components, additives usually used in the ink industry such as water and organic materials. Solvents, antioxidants, silane coupling agents, plasticizers, rust preventives, pH adjusters, defoamers, charge control agents, stress relievers, penetrants, surface conditioners, etc. are within the range that does not impair the object of the present invention. It may be appropriately selected and blended within.

In the above ink, the surface tension at the printing temperature is preferably 20 to 35 mN / m, and the viscosity at the printing temperature is preferably 5 to 15 mPa · s. The temperature of the ink at the time of printing is not particularly limited, but is preferably within a range that can be stably controlled without being affected by the environmental temperature, for example, 35 to 50 ° C.

The ink can be prepared by mixing the coloring pigment, the active energy ray-polymerizable monomer, and various components appropriately selected as necessary.

<< Composition for forming a surface protective layer (also referred to as a clear layer) >>
The surface protective layer of the present invention is, for example, by applying a clear coating composition for a surface protective layer to the surface of an ink layer and, in some cases, an exposed base material or an ink receiving layer, and then forming a film by drying or the like. Can be formed. As the coating composition used for forming the surface protective layer of the present invention, solvent-based coating materials, water-based coating materials, and various clear paints can be used.

The clear paint in the present invention refers to a transparent paint, which means a paint that does not conceal the underlying coating layer by coloring, but as described below, in order to adjust the gloss and / or the finished appearance of the design or the like. Various extender pigments, resin beads and the like can be appropriately added to the mixture.

The clear coating composition of the present invention contains an organic solvent in which the absolute value of the SP value difference is 0.70 or less with respect to the mass average SP value of the polymerizable monomer contained in the active energy ray-curable ink forming the ink layer. Contains ingredients. By setting the absolute value of the difference between the mass average SP value of the polymerizable monomer contained in the active energy ray-curable ink and the SP value of the organic solvent component contained in the clear paint to 0.70 or less, the printed matter with a small amount of monomer emission Can be obtained.

As this mechanism, the difference between the SP values of the monomer component remaining in the ink layer and the organic solvent component contained in the clear paint is reduced, so that the monomer component remaining in the ink layer is the organic solvent component contained in the clear paint. It is considered that the amount of monomer emitted from the printed matter is reduced because it easily elutes and co-boils efficiently during the drying and curing steps of the clear paint. The organic solvent component can be appropriately selected according to the active energy ray-curable ink forming the ink layer.

The mass average value of the SP value is expressed by the following formula.
Mass mean value = SP1 x W1 / ρ1 + SP2 x W2 / ρ2 + ... + SPn x Wn / ρ
In the formula, SP1, SP2, ..., SPn are SP values of each monomer, and W1, W2, ..., Wn are mass fractions of each monomer in the polymerizable compound, and ρ1, ρ2, ..., Ρn is the density of each monomer.

As the resin used in the clear coating composition of the present invention, various synthetic resins such as acrylic resin, alkyd resin, polyester resin, polyurethane resin, epoxy resin, silicone resin and fluororesin can be used, but are particularly limited. Not done. Of these resins, two or more kinds of resins can be used in combination.

The purpose of the clear coating composition of the present invention is mainly to protect the surface, but in addition, additives and the like for imparting various functionalities as shown below can be used.
For the purpose of improving weather resistance, a light stabilizer such as an ultraviolet absorber can be used in the clear coating composition, and two or more of these light stabilizers can be used in combination.

Various extender pigments, resin beads, etc. can be added in order to adjust the finished appearance such as gloss and design, and two or more of these can be combined.
A silane coupling agent or the like may be added in order to improve the adhesion to the lower ink layer and / or the ink receiving layer and / or the substrate.
In addition, a thickener, a dispersant, an antifoaming agent, a settling inhibitor, an antifungal agent, an antiseptic agent and the like generally used in the paint field can be appropriately added.

As the coating method of the clear coating composition of the present invention, a conventionally known coating method can be used without particular limitation, and specifically, air spray coating, airless spray coating, electrostatic coating, roll coater coating, and flow. Coater painting and the like can be mentioned.

Examples of the method for drying and curing the clear coating composition of the present invention include normal temperature drying, forced drying by hot air or infrared irradiation, and active energy ray irradiation, depending on the type of the clear coating composition. In order to efficiently reduce the residual monomer component in the ink layer, a drying / curing method involving thermal energy is more preferable.

≪Base material≫
The base material is not particularly limited, and is, for example, a wood building material board made of wood such as a single board, plywood, particle board, medium density fiberboard (MDF); a ceramic siding board, a flexible board, and a calcium silicate board. , Gypsum slug bar light board, wood piece cement board, asbestos cement board, pulp cement board, precast concrete board, lightweight bubble concrete (ALC) board, ceramic building material board such as gypsum board; and metal building material board such as aluminum, iron, stainless steel And so on. The surface texture of the base material is not particularly limited, and may have a smooth surface or an uneven shape. Further, the base material may be subjected to a base treatment with a sealer, a primer or the like. The thickness of the base material is not particularly limited, and is, for example, 3 to 30 mm.

≪Formation method of ink receiving layer≫
The ink receiving layer of the present invention can be formed by applying the ink receiving layer coating material according to the present invention onto the substrate, drying and curing the ink receiving layer. The coating method is not particularly limited, and examples thereof include air spray coating, airless spray coating, electrostatic coating, roll coater coating, and flow coater coating. The thickness of the ink receiving layer is not particularly limited, and is, for example, 10 to 50 μm.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" and "%" mean parts by mass and% by mass, respectively, unless otherwise specified.

<Preparation of water dispersion of resin particles 1 (Synthesis Example 1)>
386 parts of ion-exchanged water and polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt (first) in a five-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping device, and a nitrogen introduction tube. Manufactured by Kogyo Seiyaku Co., Ltd .; Aqualon KH10) 10 parts were charged, and the temperature was raised to 80 ° C. while replacing the inside of the reactor with nitrogen. After that, 4 parts of ammonium persulfate was added to the reactor, and then 97 parts of styrene, 29 parts of KBM403, 10 parts of LA82, 473 parts of methylmethacrylate and 280 parts of butylacrylate, which had been stirred and mixed in advance in a separate container, were added. 39 parts of methacrylic acid, 49 parts of diacetone acrylamide, and 579 parts of ion-exchanged water were continuously added dropwise over 3.5 hours. Then, it was aged at 80 ° C. for 5 hours while continuing stirring, and then cooled to room temperature. Then, it was neutralized to pH 9 with a 28 mass% aqueous ammonia solution to obtain a resin particle aqueous dispersion 1 (listed in Table 1).

In the present invention, the calculated Tg is a theoretically calculated value obtained by the following FOX formula.
1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + Wn / Tgn
In the formula, Tg is the calculated Tg (° K), W1, W2, ..., Wn is the mass fraction of each monomer, and Tg1, Tg2, ..., Tgn are homopolymers of each monomer. The glass transition temperature (° K) of the polymer.

・ ST; Styrene ・ KBM403; 3-Glysidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
LA82; 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (manufactured by ADEKA)
-MMA; Methyl Methacrylate-BA; Butyl Acrylate-MAA; Methacrylic Acid-DAAM; Diacetone Acrylamide <Preparation of Paint 1 for Ink Receiving Layer>
According to the formulation shown in Table 2, the raw material and the titania beads were mixed and then dispersed by a bead mill. After the dispersion, the titania beads were removed to prepare a paint 1 for an ink receiving layer.

1) Titanium oxide, density 3.8 g / cm ³ , (TITONE R-62N, manufactured by Sakai Chemical Industry Co., Ltd.)
2) Heavy calcium carbonate, density 2.7 g / cm ³ , average particle diameter 2 μm (made by Maruo Calcium)
3) SN Deformer 1316 (manufactured by San Nopco Ltd.)
4) ASE-60 (manufactured by Rohm and Hearth)
5) Proxel AM (manufactured by Arch Chemicals)
6) TINUVIN 1130 (manufactured by BASF)
7) Sanol LS-292 (manufactured by Sankyo Kasei Co., Ltd.)

<Preparation of active energy ray-curable ink>
According to the formulation shown in Table 3, the raw material and zirconia beads (φ0.5 mm) were mixed and then dispersed by a bead mill. After the dispersion, the zirconia beads were removed to prepare a black UV ink (hereinafter, also referred to as UV ink).

8) MA100 (carbon black pigment, product name manufactured by Mitsubishi Chemical Corporation)
9) Light acrylate PO-A (phenoxyethyl acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -22 ° C, SP value: 10.4
10) Light acrylate P2H-A (phenoxydiethylene glycol acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -35 ° C, SP value: 10.2
11) Light acrylate IB-XA (isobornyl acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: 94 ° C., SP value: 8.87
12) Light acrylate EC-A (ethoxy-diethylene glycol acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -70 ° C, SP value: 9.96
13) Light acrylate DPM-A (methoxydipropylene glycol acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -30 ° C, SP value: 9.69
14) CTFA (Cyclic trimethylolpropane formal acrylate, trade name manufactured by Osaka Organic Chemical Industry Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: 27 ° C., SP value: 9.95
15) 4-HBA (4-hydroxybutyl acrylate, trade name manufactured by Osaka Organic Chemical Industry Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -32 ° C, SP value: 10.8
16) Light acrylate THF-A (tetrahydrofurfuryl acrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -12 ° C, SP value: 10.1
17) Praxel FA-2D (lactone-modified acrylate, trade name manufactured by Daicel Corporation) Specific gravity: 1.2, number of functional groups: 1, Tg: -40 ° C, SP value: 10.5
18) DAAM (Diacetone Acrylamide, trade name manufactured by Nihon Kasei Co., Ltd.) Specific gravity: 1.2, Number of functional groups: 1, Tg: 77 ° C., SP value: 11.5
19) HEA (2-hydroxyethyl acrylate, trade name manufactured by Osaka Organic Chemical Industry Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -15 ° C, SP value: 11.4
20) IDAA (isodecyl acrylate, trade name manufactured by Osaka Organic Chemical Industry Co., Ltd.) Specific gravity: 1.2, number of functional groups: 1, Tg: -62 ° C., SP value: 8.98
21) Light acrylate 1,6HX-A (1,6-hexanediol diacrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 2, Tg: 63 ° C., SP value: 9.82
22) Light acrylate 1,9ND-A (1,9-nonanediol diacrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 2, Tg: 68 ° C., SP value: 9.63
23) Light acrylate DCP-A (dimethylol-tricyclodecanediacrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 2, Tg: 187 ° C, SP value: 9.72
24) Light acrylate TMP-A (trimethylolpropane triacrylate, trade name manufactured by Kyoeisha Chemical Co., Ltd.) Specific gravity: 1.2, number of functional groups: 3, Tg: 62 ° C., SP value: 9.90
25) IRGACURE TPO (acylphosphinoxide-based photopolymerization initiator, trade name manufactured by BASF)
26) IRGACURE 184 (alkylphenone-based photopolymerization initiator, trade name manufactured by BASF)
27) KAYACURE DETX-S (2,4-diethylthioxanthone, trade name manufactured by Nippon Kayaku Co., Ltd.)
28) DISPERBYK-2155 (Product name manufactured by BYK)
29) BYK-UV3500 (product name manufactured by BYK)

The surface tension of the active energy ray-curable ink was measured at a temperature of 45 ° C. using a surface tension meter (CBVP-Z manufactured by Kyowa Surface Chemistry). The viscosity of the active energy ray-curable ink was measured at a temperature of 45 ° C. and a shear rate of 10 s ^-1 using a leometer (MCR301 manufactured by AntonioPysica).

<Preparation example of paint composition for surface protective layer (hereinafter referred to as "clear paint")>
The raw materials were mixed according to the formulation shown in Tables 4 and 5 to prepare a clear paint.

30) Polydurex G613 (acrylic silicone resin emulsion, trade name manufactured by Asahi Kasei Corporation)
31) Lumiflon FE-4400 (fluororesin emulsion, trade name manufactured by Asahi Glass Co., Ltd.)
32) Acryset EX-41 (acrylic resin emulsion, trade name manufactured by Nippon Shokubai Co., Ltd.)
33) Udable E-670 (HALS-containing acrylic resin emulsion, trade name manufactured by Nippon Shokubai Co., Ltd.)
34) JONCRYL 538 (Acrylic resin emulsion, product name made by BASF)

<Manufacturing example of building board (decorative test board)>
1. 1. A water-based sealer (manufactured by Dai Nippon Toryo Co., Ltd., product name: Aqueous Mighty Sealer Multi) is applied to the surface of the base material slate plate (150 mm x 70 mm x 5 mm, manufactured by TP Giken Co., Ltd.) with an air spray so that the coating amount is 100 g / m ² . Then, the substrate was prepared by drying at room temperature for 2 hours.
2. 2. Ink receiving layer With the coated base material heated to 60 ° C, the above-mentioned ink receiving layer paint is applied to the coated surface of the base material with a coating amount of 120 g / m ² (equivalent to a dry film thickness of 30 μm). I painted it with an airless spray. Then, it was dried at 100 degreeC for 3 minutes to form an ink receiving layer. The substrate temperature was measured using an infrared radiation type non-contact thermometer (ISK-8700II, manufactured by AS ONE Corporation).
3. 3. Ink layer After the ink receiving layer is prepared, the gradation pattern (recording density is from 10%) of the UV ink (black) prepared above using an inkjet printer with the substrate temperature adjusted to 50 to 60 ° C. A solid image) recorded stepwise up to 100% in 20% increments) was formed. At this time, the temperature of the ink at the time of ejecting the ink was 45 ° C. After forming the pattern, the ink was cured by irradiating with an ultraviolet ray having a peak illuminance of 800 mW / cm ² and an integrated light amount of 300 mJ / cm ² with a metal halide lamp. The substrate temperature was measured using an infrared radiation type non-contact thermometer (ISK-8700II, manufactured by AS ONE Corporation).
4. Surface protective layer After the ink is cured, the above-mentioned clear paint is applied so that the coating amount is 80 g / m ² (equivalent to a dry film thickness of 25 μm) in a state where the surface temperature of the cured coating film is adjusted to 50 ° C. did. After painting, it was dried at 80 ° C. for 20 minutes to form a surface protective layer. The surface temperature was measured using an infrared radiation type non-contact thermometer (ISK-8700II, manufactured by AS ONE Corporation).

[Evaluation methods]
The color development, adhesion, water resistance, weather resistance of the printed matter after laminating the surface protective layer, the monomer emission rate of the printed matter after laminating the ink layer, and the monomer emission rate of the printed matter after laminating the surface protective layer were evaluated by the following methods. .. The measurement results are shown in Tables 11 to 13. Unless otherwise specified, the evaluation was performed in an atmosphere of 23 ° C. and 50% RH.
(1) Color development The color development was evaluated by observing the gradation pattern one day after the preparation of the decorative test plate with the naked eye and a microscope. The evaluation criteria are as follows.
〇: The original color of the ink is printed evenly and evenly, and there is no bleeding.
X: The gradation pattern has unevenness, rubbing, and / or bleeding.

(2) Adhesiveness (based on JIS K5600-5-6: 1999)
A cutter knife was used to make cuts in the produced printed matter at intervals of 2 mm in length and width, 100 squares were prepared, and a cellophane tape (registered trademark) peeling test was performed. The evaluation criteria are as follows.
◯: Classification 0-1
Δ: Classification 2
×: Classification 3 to 5
The categories 0 to 5 described in 8.3 of JIS K 5600-5-6: 1999 are as follows.
-Category 0: The edges of the cut are completely smooth and there is no peeling in the eyes of any grid.
-Category 1: The residual rate of the laminated coating film is 95 to 99%.
-Category 2: The residual rate of the laminated coating film is 85% or more and less than 95%.
-Category 3: The residual rate of the laminated coating film is 65% or more and less than 85%.
-Category 4: Residual rate of laminated coating film is 0%% or more and less than 65%.
-Category 5: Any degree of peeling that cannot be classified even in Category 4.

(3) Water resistance (based on JIS K 5600-6-2: 1999)
The produced printed matter was immersed in a constant temperature water bath kept at 40 ° C., and after 240 hours, it was taken out and dried. After that, the appearance such as swelling and whitening that occurred was observed, and the adhesiveness was evaluated by the same method as the method (2) above. The evaluation criteria are as follows.
⊚: There is no appearance abnormality such as swelling and whitening, and the adhesiveness is classified as 0.
◯: There is no appearance abnormality such as swelling and whitening, and the adhesiveness is classification 1. Δ: There is no appearance abnormality such as swelling and whitening, and the adhesiveness is classification 2 to 3.
X: Appearance abnormalities such as swelling and whitening are observed. Adhesion is classified into 4 to 5.

(4) Accelerated weather resistance (based on JIS K 5600-7-7: 2008)
The produced printed matter was subjected to an accelerated weather resistance test by a weatherometer Ci4000 (manufactured by Atlas) according to the xenon lamp method described in JIS K 5600-7-7. The test time was up to 1000 hours, the appearance of the coating film was visually evaluated, and the adhesiveness was evaluated by the same method as the method (2) above. The evaluation criteria are as follows.
〇: There is no appearance abnormality such as swelling, chalking, cracks, etc., and the adhesiveness is classified as 0 to 1.
Δ: There is no appearance abnormality such as swelling, chalking, and cracks, and the adhesiveness is classified into 2 to 3.
X: Appearance abnormalities such as swelling, chalking, and cracks are observed. Adhesion is classified into 4 to 5.

(5) Monomer emission rate According to JIS A 1901: 2015, the monomer emission rate of the printed matter after the ink layer was laminated and the printed matter after the surface protection layer was laminated was calculated by gas chromatography measurement using a small chamber. When the monomer emission rate is 1.0 μg / m ² · h or less, it can be said that the monomer emission amount is small.
The inside of the 1.20 L chamber was set to a temperature of 28 ° C., a humidity of 50% RH, and a ventilation rate of 0.5 times / h, and stabilized for 1 hour.
2. 2. The air in the chamber was sampled, and the amount of monomer detected (background) before setting the test piece was measured.
3. 3. The specimen was set in the chamber and the monomer was allowed to dissipate for 2 hours. The measurement was performed when the temperature of the test piece dropped to 28 ° C. one hour after the test piece was prepared.
4. The air in the chamber was sampled, and the amount of monomer detected after the test piece was placed was measured.
5. The monomer concentration was calculated using the calibration curve prepared from the standard reagent, and the emission rate of each monomer was calculated from the following formula.
(formula)
EFa = Ct × n / L
EFa: Monomer emission rate per unit area (μg / m ² · h)
n: Ventilation frequency (times / h)
Ct: Concentration of monomer in the chamber at elapsed time t L: Sample load factor (m ² / m ³ ) (Ratio of small chamber volume to surface area of test piece)

<Evaluation result>

As described above, the printed matter of the example is a printed matter in which the amount of unreacted monomer emitted is small, and the appearance and durability of the printed matter are also excellent. On the other hand, in Comparative Examples 1 to 9, the difference between the solubility parameter (A) of the polymerizable compound and the solubility parameter (B) of the organic solvent component contained in the water-based paint | (A)-(B) | is 0. It exceeds 70, and the result is that the monomer emission rate of the surface protective layer is high. Further, even in Comparative Example 10 in which the water-based paint forming the surface protective layer was not dried at a temperature equal to or higher than the glass transition temperature of the surface protective layer after being coated, the result was that the monomer emission rate of the surface protective layer was high.

Claims (4)

A method for producing a printed matter, which comprises an ink layer composed of an ink receiving layer and a cured product of an active energy ray-curable ink containing a polymerizable compound on a substrate, and a surface protective layer laminated on the ink layer. Therefore, the monomer emission rate of the ink layer is 10.0 μg / m ² · h or less, and the monomer emission rate after forming the surface protective layer is 1.0 μg / m ² · h or less.
The ink layer contains at least one crosslinkable monomer and 25 to 85% by mass of at least one structural unit derived from an ethylenically unsaturated monomer having a solubility parameter of 9.50 to 13.0. Provided on the ink receiving layer including coalescence ,
The proportion of the monofunctional monomer contained in the polymerizable compound forming the ink layer is 50% by mass or more.
Printed matter manufacturing method. The absolute value of the difference between the mass average value of the solubility parameter of the polymerizable monomer contained in the active energy ray-curable ink and the solubility parameter of the organic solvent component different from the monomer contained in the composition forming the surface protective layer is The method for producing a printed matter according to claim 1 , which is 0.70 or less. The method for producing a printed matter according to claim 1 or 2 , wherein the ink receiving layer contains a pigment and the glass transition temperature of the polymer of the polymerizable compound forming the ink layer is −35 to 35 ° C. The method for producing a printed matter according to any one of claims 1 to 3 , wherein the coating film forming the surface protective layer is dried at a temperature equal to or higher than the glass transition temperature.