JP2020111659A - Coating composition for ink-receiving layer, ink-receiving layer, inorganic decorative plate, and method for producing the same - Google Patents

Abstract

To provide a coating composition for ink-receiving layer which can suppress reduction in ink-receiving capability and can stabilize color development of ink.SOLUTION: A coating composition for ink-receiving layer is used for forming an ink-receiving layer 1. The coating composition for ink-receiving layer contains a binder resin 3, inorganic particles 4 and resin beads 5. A content of the resin beads 5 is within a range of 10 pts.mass or more and 60 pts.mass or less with respect to 100 pts.mass of a solid content of the binder resin 3. The maximum particle diameter of the resin beads 5 is within a range of 0.1 times or more and 5 times or less with respect to the film thickness of the ink-receiving layer 1. The average particle diameter of the resin beads 5 is 0.5 times or more with respect to the film thickness of the ink-receiving layer 1.SELECTED DRAWING: Figure 1

Description

The present invention generally relates to an ink-receiving layer coating composition, an ink-receiving layer, an inorganic decorative board, and a method for producing the same. More specifically, the present invention relates to a coating composition for an ink receiving layer containing inorganic particles, an ink receiving layer, an inorganic decorative board, and a method for producing the same.

Patent Document 1 discloses a method for manufacturing a decorative building board. In this method, first, an ink receiving layer having a specific arithmetic average roughness is formed on a metal-based substrate or a ceramic-based substrate. Then, an actinic ray curable ink is jetted onto this ink receiving layer to irradiate the actinic ray for a predetermined time.

BACKGROUND ART Conventionally, when industrially manufacturing an inorganic decorative board such as the decorative building board of Patent Document 1, a manufacturing line is assembled so as to enable continuous production. That is, while the inorganic base material is continuously conveyed, the ink receiving layer coating composition is applied to the inorganic base material to form the ink receiving layer. Furthermore, subsequently, the inorganic base material is manufactured by carrying out inkjet coating on the ink receiving layer while transporting the inorganic base material on which the ink receiving layer is formed.

JP, 2005-105508, A

Two or more types of inorganic decorative boards may be manufactured in one production line for inorganic decorative boards. In such a case, it is necessary to change the inorganic base material or change the image data of inkjet coating. While it is necessary to stop the inkjet coating during such an operation, the content of the ink receiving layer coating composition may settle if left as it is. To prevent this, set up a circulatory pipe to circulate the paint composition for the ink-receiving layer sucked up from the paint tank by a plunger pump in the pipe while the inkjet coating is stopped to prevent sedimentation of the contents. ing.

However, when comparing the inorganic decorative board manufactured after the restart of inkjet coating and the inorganic decorative board manufactured before the stop of inkjet coating, it was found that there is a difference in coloring property between the both. The present inventors have found out that the cause is the alteration of the ink-receiving layer coating composition, and have completed the present invention.

An object of the present invention is to provide a coating composition for an ink receiving layer, an ink receiving layer, an inorganic decorative board, and a method for producing the same, which can suppress deterioration of ink receiving ability and can stabilize the color developability of the ink. To do.

The coating composition for an ink receiving layer according to one aspect of the present invention is used for forming an ink receiving layer. The ink receiving layer coating composition contains a binder resin, inorganic particles and resin beads. The content of the resin beads is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin. The maximum particle diameter of the resin beads is in the range of 0.1 times or more and 5 times or less the thickness of the ink receiving layer. The average particle diameter of the resin beads is 0.5 times or more the thickness of the ink receiving layer.

The coating composition for an ink receiving layer according to one aspect of the present invention contains a binder resin, inorganic particles and resin beads. The content of the inorganic particles is in the range of 55 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin. The average particle diameter of the resin beads is in the range of 10 μm or more and 60 μm or less. The content of the resin beads is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin. The ratio of the number of particles having a particle diameter of 10 μm or more and 50 μm or less to the total number of particles constituting the inorganic particles and the resin beads is 10% or more and 40% or less.

The ink receiving layer according to one aspect of the present invention is obtained by coating and drying the coating composition for an ink receiving layer.

An inorganic decorative board according to an aspect of the present invention includes an inorganic base material, the ink receiving layer provided on the inorganic base material, and an ink layer provided on the ink receiving layer.

A method for producing an inorganic decorative board according to one aspect of the present invention comprises a step of providing an ink receiving layer by coating the ink receiving layer coating composition on an inorganic base material and drying, and an inkjet on the ink receiving layer. Printing and providing an ink layer.

According to the present invention, it is possible to suppress a decrease in ink receiving ability and stabilize the color developability of ink.

FIG. 1A is a schematic cross-sectional view of an inorganic decorative plate formed by using the ink-receiving layer coating composition according to the present embodiment before being circulated in a pipe. FIG. 1B is a schematic cross-sectional view of an inorganic decorative plate formed by circulating the coating composition for an ink receiving layer according to the present embodiment in a pipe. FIG. 2A is a particle diameter distribution graph of resin beads before being circulated in the pipe. FIG. 2B is a particle diameter distribution graph of resin beads after being circulated in the pipe. FIG. 3A is a particle size distribution graph of inorganic particles before being circulated in a pipe. FIG. 3B is a particle size distribution graph of inorganic particles after being circulated in the pipe. FIG. 4A is a schematic cross-sectional view of an inorganic decorative board formed by using the conventional ink-receiving layer coating composition before being circulated in a pipe. FIG. 4B is a schematic cross-sectional view of an inorganic decorative board formed by circulating a conventional ink-receiving layer coating composition in a pipe.

(1) Outline The present inventors have found the following problems in the conventional ink-receiving layer coating composition.

A conventional ink-receiving layer coating composition contains a binder resin 3 and inorganic particles 4. When the ink-receiving layer coating composition is circulated in the pipe, at least a part of the inorganic particles 4 has a small particle size, and the ink-receiving layer coating composition is deteriorated.

4A and 4B are schematic cross-sectional views schematically showing a conventional inorganic decorative board 10. FIG. 4A shows an inorganic decorative board 10 formed using the ink-receiving layer coating composition before circulation. FIG. 4B shows an inorganic decorative board 10 formed by using the ink receiving layer coating composition after circulation. 1 is an ink receiving layer, 3 is a binder resin, 4 is inorganic particles, 41 is primary particles, 42 is agglomerated particles (secondary particles), 6 is an inorganic base material, and 8 is an undercoat layer.

The inorganic particles 4 include primary particles 41 and aggregated particles 42. The aggregated particles 42 are secondary particles formed by aggregating a plurality of primary particles 41. The ink is more easily fixed on the aggregated particles 42 than on the primary particles 41. Since many agglomerated particles 42 are present in the ink-receiving layer coating composition before being circulated, coloring of the ink layer 7 is good (see FIG. 4A). Since the number of primary particles 41 forming the aggregated particles 42 is not strictly constant, the size of the aggregated particles 42 has a distribution.

When the coating composition for the ink receiving layer circulates in the pipe, a shearing force acts on the inorganic particles 4. When this shearing force acts on the agglomerated particles 42, the agglomerated particles 42 are separated and become smaller agglomerated particles 42 or primary particles 41. Therefore, the color development of the ink layer 7 is not good (see FIG. 4B). As described above, in the conventional ink receiving layer coating composition, the ink receiving ability is likely to decrease, and the color developability of the ink may become unstable.

The problems described above can be solved by the ink-receiving layer coating composition according to the present embodiment described below.

The ink-receiving layer coating composition according to this embodiment contains a binder resin 3, inorganic particles 4, and resin beads 5.

1A and 1B are schematic cross-sectional views schematically showing the inorganic decorative board 10 according to the present embodiment. FIG. 1A shows an inorganic decorative board 10 formed using a coating composition for an ink receiving layer before circulation. FIG. 1B shows an inorganic decorative board 10 formed using the coating composition for an ink receiving layer after circulation.

When the coating composition for the ink receiving layer circulates in the pipe, the agglomerated particles 42 disperse and change into smaller agglomerated particles 42 or primary particles 41. The resin beads 5 can complement the lost original aggregated particles 42. That is, even if a shearing force is applied to the resin beads 5, the resin beads 5 are less likely to be broken and the size thereof can be maintained. Therefore, after the circulation, the ink layer 7 having the same coloring property as that before the circulation can be obtained (see FIGS. 1A and 1B). As described above, according to the coating composition for an ink receiving layer of the present embodiment, it is possible to suppress the deterioration of the ink receiving ability and to stabilize the color developability of the ink.

(2) Details (2.1) Ink-receiving layer coating composition The ink-receiving layer coating composition according to the present embodiment is used for forming the ink-receiving layer 1. The ink receiving layer 1 is a layer that absorbs and fixes ink, and the ink layer 7 is formed on the ink receiving layer 1. More specifically, the ink layer 7 is formed near the upper portion of the ink receiving layer 1. Here, the vicinity of the upper part of the ink receiving layer 1 includes a part in which all or part of the ink is absorbed. The ink receiving layer 1 is also called the ink receiving layer 1.

There are two types of ink-receiving layer coating compositions according to this embodiment. That is, a first ink-receiving layer coating composition and a second ink-receiving layer coating composition. These will be described separately below. The term "ink-receiving layer coating composition" includes the above two types.

(2.1.1) First ink-receiving layer coating composition The first ink-receiving layer coating composition contains a binder resin 3, inorganic particles 4, and resin beads 5. The first ink receiving layer coating composition may further contain water. The first ink-receiving layer coating composition may further contain at least one of a color pigment, an additive and a film-forming auxiliary, as long as the effect of the present invention is not impaired. Hereinafter, each component will be described in order.

The binder resin 3 is not particularly limited, but examples thereof include acrylic resin, silicone resin, fluororesin, and polyester resin. Among these, acrylic resins are preferable from the viewpoints of color developability, weather resistance, and cost. Specific examples of the acrylic resin include acrylic resin, acrylic-styrene resin, acrylic-silicone resin, and acrylic-urethane resin.

The inorganic particles 4 are not particularly limited as long as they can absorb and fix ink. The inorganic particles 4 are preferably porous materials. Since the porous material has a large number of pores, it is easy to absorb and fix the ink in these pores due to the capillary phenomenon. Specific examples of the inorganic particles 4 include calcium carbonate, silica, and zeolite. The inorganic particles 4 may have a side surface as a color pigment (inorganic pigment), but in that case, the side surface as the inorganic particle 4 is prioritized.

Preferably, the inorganic particles 4 are aggregated particles 42. The aggregated particles 42 are secondary particles formed by aggregating a plurality of primary particles 41. A gap is formed between the plurality of primary particles 41 forming the aggregated particles 42, and the gap is likely to absorb ink. Therefore, if the inorganic particles 4 are the agglomerated particles 42, it becomes easier to capture the ink and suppress the bleeding.

The average particle diameter of the inorganic particles 4 is not particularly limited, but is, for example, in the range of 2 μm or more and 20 μm or more. In the present specification, the “average particle diameter” means 50% volume particle diameter (D50).

The resin beads 5 are not particularly limited, but are preferably transparent or white. Specific examples of the resin beads 5 include acrylic beads, styrene beads, melamine beads, acrylic-styrene beads, silicone beads, benzoguanamine beads, benzoguanamine-formaldehyde beads, polycarbonate beads, and polyethylene beads. However, when the inorganic decorative board 10 is used as an exterior material for outdoor use, it is preferable that the resin beads 5 do not contain urethane beads. This is because there is a possibility of yellowing.

The content of the resin beads 5 is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin 3.

When the content of the resin beads 5 is less than 10 parts by mass, the color difference before and after the circulation may increase. For example, there is a possibility that the difference between the lightness ^{(L *)} (ΔL ^*) increases.

If the content of the resin beads 5 exceeds 60 parts by mass, the leveling property may deteriorate. That is, unevenness is likely to remain on the surface of the ink receiving layer 1, the probability that the resin beads 5 are exposed from the surface of the ink receiving layer 1 increases, and the color developability of the ink may deteriorate. Further, when the content of the resin beads 5 exceeds 60 parts by mass, the film forming property (film forming property) may be deteriorated. That is, cracks are likely to occur in the ink receiving layer 1. Further, when the content of the resin beads 5 exceeds 60 parts by mass, the practicability becomes low from the viewpoint of cost.

The maximum particle diameter of the resin beads 5 is within a range of 0.1 times to 5 times the thickness T of the ink receiving layer 1. The film thickness T of the ink receiving layer 1 means the shortest thickness (see FIGS. 1A and 1B). The specific film thickness T of the ink receiving layer 1 is not particularly limited. When the maximum particle diameter of the resin beads 5 is 0.1 times or more the film thickness T of the ink receiving layer 1, it is possible to suppress an increase in the color difference before and after the circulation. When the maximum particle size of the resin beads 5 is 5 times or less the film thickness T of the ink receiving layer 1, the ratio of the particle size of the resin beads 5 to the film thickness T of the ink receiving layer 1 or more decreases, and the color development Can be suppressed.

The average particle diameter of the resin beads 5 is 0.5 times or more the thickness T of the ink receiving layer 1. Since the average particle diameter of the resin beads 5 is 0.5 times or more the thickness T of the ink receiving layer 1, it is possible to suppress an increase in color difference before and after the circulation. The ratio of the average particle diameter of the resin beads 5 to the film thickness T of the ink receiving layer 1 is not particularly limited, but is preferably 1 time or less.

Preferably, the breaking strength of the resin beads 5 is larger than the breaking strength of the inorganic particles 4. In other words, when the same degree of shearing force acts on each of the resin beads 5 and the inorganic particles 4, the inorganic particles 4 are easier to separate into two or more than the resin beads 5. In other words, if the resin beads 5 and the inorganic particles 4 have the same strength or hardness, the resin beads 5 have higher toughness (tenacity) than the inorganic particles 4, and are less likely to be brittle. .. As described above, the breaking strength of the resin beads 5 is larger than the breaking strength of the inorganic particles 4, so that when the ink receiving layer coating composition is circulated by a pump, the breaking of the inorganic particles 4 is prevented. It can be suppressed by 5.

Next, the magnitude relationship between the fracture strength of the resin beads 5 and the inorganic particles 4 will be described. The magnitude relationship of the breaking strength can be confirmed by examining the particle diameter distribution of the resin beads 5 and the inorganic particles 4 in the ink receiving layer coating composition before and after the circulation.

FIG. 2A is a particle diameter distribution graph of the resin beads 5 in the ink-receiving layer coating composition before the ink-receiving layer coating composition is circulated in the pipe. FIG. 2B is a particle diameter distribution graph of the resin beads 5 in the ink-receiving layer coating composition after the ink-receiving layer coating composition is circulated in the pipe. The ink-receiving layer coating composition used here was obtained by removing the inorganic particles 4 from the ink-receiving layer coating composition of Example 1 described later (see Table 1).

Comparing FIG. 2A and FIG. 2B, it can be seen that there is almost no change in the particle diameter distribution graph of the resin beads 5 before and after the circulation. The peak shape and peak position of the particle size distribution are almost unchanged. Thus, it can be seen that the resin beads 5 are not easily broken even when a shearing force acts.

On the other hand, FIG. 3A is a particle size distribution graph of the inorganic particles 4 in the ink-receiving layer coating composition before the ink-receiving layer coating composition is circulated in the pipe. FIG. 3B is a particle diameter distribution graph of the inorganic particles 4 in the ink-receiving layer coating composition after the ink-receiving layer coating composition is circulated in the pipe. The ink-receiving layer coating composition used here was obtained by removing the resin beads 5 from the ink-receiving layer coating composition of Example 1 described later.

By comparing FIG. 3A and FIG. 3B, it can be seen that there is a change in the particle size distribution graph of the inorganic particles 4 before and after the circulation. The peak shape of the particle size distribution collapses, and the peak of the particle size distribution shifts to the small particle size side. Thus, it can be seen that the inorganic particles 4 are easily broken when a shearing force acts.

The color pigment is not particularly limited, and examples thereof include organic pigments and inorganic pigments.

Specific examples of organic pigments include nitrosos, dyed lakes, azo lakes, insoluble azos, monoazos, disazos, condensed azos, benzimidazolones, phthalocyanines, anthraquinones, perylenes, quinacridones, dioxazines. And isoindolines, azomethines, and pyrrolopyrroles.

Specific examples of the inorganic pigment include oxides, hydroxides, sulfides, ferrocyanides, chromates, carbonates, silicates, phosphates, carbons (carbon black), and metal powders. And the like.

Specific examples of additives include heat stabilizers, antioxidants, preservatives, defoamers, penetrants, reducing agents, leveling agents, pH adjusters, pigment derivatives, polymerization inhibitors, ultraviolet absorbers, and photostabilizers. Agents and the like.

Specific examples of the film-forming aid include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and benzyl alcohol.

(2.1.2) Second ink-receiving layer coating composition The second ink-receiving layer coating composition contains a binder resin 3, inorganic particles 4, and resin beads 5. The second ink-receiving layer coating composition may further contain water. The second ink-receiving layer coating composition may further contain at least one of a coloring pigment, an additive and a film-forming auxiliary, as long as the effect of the present invention is not impaired. Hereinafter, each component will be described in order. However, description of items that are the same as those of the first ink-receiving layer coating composition will be omitted.

The content of the inorganic particles 4 is in the range of 55 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin 3. When the content of the inorganic particles 4 is 55 parts by mass or more, it is possible to prevent the color development from becoming thin. When the content of the inorganic particles 4 is 120 parts by mass or less, it is possible to suppress the deterioration of the film forming property (film forming property). For example, the generation of cracks can be suppressed.

The average particle diameter of the resin beads 5 is in the range of 10 μm or more and 60 μm or less. When the average particle diameter of the resin beads 5 is 10 μm or more, it is possible to prevent the color difference before and after the circulation from increasing. When the average particle size of the resin beads 5 is 60 μm or less, the ratio of the particle size of the resin beads 5 to the film thickness T of the ink receiving layer 1 or more decreases, and it is possible to prevent the color development from becoming thin. .. In the second ink-receiving layer coating composition, the maximum particle size of the resin beads 5 is not particularly limited.

The ratio of the number of particles having a particle diameter of 10 μm or more and 50 μm or less to the total number of particles constituting the inorganic particles 4 and the resin beads 5 is 10% or more and 40% or less. When the ratio of the number of particles within the range of the particle diameter of 10 μm or more and 50 μm or less is 10% or more, it is possible to suppress the fading of the color. When the ratio of the number of particles in the range of the particle size of 10 μm or more and 50 μm or less is 40% or less, the deterioration of the film forming property can be suppressed. For example, the generation of cracks can be suppressed. Furthermore, the ratio of the particle diameter of the resin beads 5 to the film thickness T of the ink receiving layer 1 or more is reduced, and it is possible to suppress thinning of color development.

(2.1.3) Main Effects of Ink Receiving Layer Coating Composition According to the ink receiving layer coating composition according to the present embodiment, it is possible to suppress deterioration of ink receiving ability and to develop ink color. The sex can be stabilized. In other words, the coating composition for the ink receiving layer after the circulation can retain the same properties as the coating composition for the ink receiving layer before the circulation. This effect is largely due to the addition of the resin beads 5.

During the circulation of the coating composition for the ink receiving layer, at least a part of the inorganic particles 4 may be broken by the shearing force to reduce the particle size.

On the other hand, during the circulation of the ink receiving layer coating composition, the resin beads 5 are less likely to be broken even when subjected to shearing force, and can retain the size before the circulation. Therefore, the resin beads 5 can complement the inorganic particles 4 that have lost their original size. Further, the resin beads 5 may have an effect of suppressing the destruction of the inorganic particles 4.

Therefore, the ink receiving layer 1 formed of the ink receiving layer coating composition according to this embodiment has excellent color reproducibility.

(2.1.4) Modified Example The first ink-receiving layer coating composition may employ at least one of the configurations of the second ink-receiving layer coating composition.

The second ink-receiving layer coating composition may employ at least one of the configurations of the first ink-receiving layer coating composition.

(2.2) Ink Receiving Layer The ink receiving layer 1 according to this embodiment is obtained by coating and drying the ink receiving layer coating composition. That is, the ink receiving layer 1 is a dried product of the ink receiving layer coating composition. The object to be coated is not particularly limited, and examples thereof include the inorganic base material 6.

The film thickness T of the ink receiving layer 1 is preferably in the range of 5 μm or more and 40 μm or less. When the thickness of the ink receiving layer 1 is 5 μm or more, the ink receiving layer 1 can cover the entire surface of the inorganic base material 6 or the undercoat layer 8. When the thickness of the ink receiving layer 1 is 40 μm or less, generation of cracks can be suppressed.

Since the ink receiving layer 1 is formed of the ink receiving layer coating composition according to this embodiment, the ink receiving ability is stable even if there is a difference in circulation time by the pump. By containing the resin beads 5 in the ink receiving layer 1, the strength of the ink receiving layer 1 can be improved.

(2.3) Inorganic Decorative Plate The inorganic decorative plate 10 according to this embodiment can be used as an exterior material such as an outer wall material. The inorganic decorative board 10 includes an inorganic base material 6, an ink receiving layer 1, and an ink layer 7. The inorganic decorative board 10 may further include the undercoat layer 8. The case where the undercoat layer 8 is provided will be described below.

The inorganic base material 6 is not particularly limited, but examples thereof include a cement board, a ceramic siding board, a metal siding board, a concrete block, and a slate board.

The undercoat layer 8 is provided between the inorganic base material 6 and the ink receiving layer 1. The undercoat layer 8 is not particularly limited, and examples thereof include an enamel coating film having an acrylic skeleton. The undercoat layer 8 can improve the adhesiveness between the inorganic base material 6 and the ink receiving layer 1. Furthermore, the undercoat layer 8 can also hide the color of the inorganic base material 6. The thickness of the undercoat layer 8 is not particularly limited, but is, for example, in the range of 10 μm or more and 50 μm or less.

The ink receiving layer 1 is provided on the inorganic base material 6 via the undercoat layer 8.

The ink layer 7 is provided on the ink receiving layer 1. More specifically, the ink layer 7 is provided near the upper part of the ink receiving layer 1. The ink forming the ink layer 7 is not particularly limited, but an ultraviolet curable ink is preferable. The ultraviolet curable ink contains a reactive monomer, a reactive oligomer, a photopolymerization initiator and a pigment. The ultraviolet curable ink may further contain an additive.

The pigment concentration of the ultraviolet curable ink is preferably 0.5 part by mass or more and 20 parts by mass or less per 100 parts by mass of the ultraviolet curable ink. If the pigment concentration is less than 0.5 parts by mass, coloring may be insufficient and the desired “image” may not be formed. On the other hand, if the pigment concentration exceeds 20 parts by mass, the viscosity of the ultraviolet curable ink may become too high and the ink may not be ejected from the nozzle of the inkjet printer. The pigment concentration referred to here is the pigment concentration with respect to the non-volatile components of the ultraviolet curable ink.

Examples of the reactive monomer used in the ultraviolet curable ink include hexafunctional acrylates such as dipentaerythritol hexaacrylate and modified products thereof; pentafunctional acrylates such as dipentaerythritol hydroxypentaacrylate; pentaditrimethylolpropane tetraacrylate. Tetrafunctional acrylates such as pentaerythritol tetraacrylate; Trifunctional acrylates such as trimethylolpropane triacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, glyceryl triacrylate; hydroxypivalic acid neopentyl glycol diacrylate. , Polytetramethylene glycol diacrylate, trimethylolpropane acrylic acid benzoate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene Glycol (600) diacrylate, neopentyl glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol -Difunctional acrylates such as tricyclodecane diacrylate, bisphenol A diacrylate; caprolactone acrylate, tridecyl acrylate, isodecyl acrylate, isooctyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol diacrylate, 2 -Hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, neopentyl furicol acrylic acid benzoate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, butoxyethyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-triethylene glycol acrylate , Methoxy-polyethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, phenoxy-polyethylene glycol acrylate, nonylphenol acrylate, tetrahydrofurfuryl acrylate, isovo Runyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl-succinic acid, 2-acryloyloxyethyl-phthalic acid, and 2-acryl Mention may be made of monofunctional acrylates such as loyloxyethyl-2-hydroxyethyl-phthalic acid.

Among them, a bifunctional monomer is preferable in terms of excellent toughness and flexibility. Among the bifunctional monomers, aliphatic reactive monomers composed of hydrocarbons, such as 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and 1,3-butanediol, are yellowing-resistant. Diacrylate, 1,4-butanediol diacrylate, and 1,9-nonanediol diacrylate are preferable.

Examples of the reactive monomer further include reactive monomers obtained by adding a functional group of phosphorus or fluorine, ethylene oxide or propylene oxide to the reactive monomer. Moreover, these reactive monomers can be used individually or in combination of 2 or more types.

The reactive monomer is preferably contained in the range of 50 parts by mass or more and 85 parts by mass or less in 100 parts by mass of the ultraviolet curable ink. When the content of the reactive monomer is less than 50 parts by mass, the viscosity of the ultraviolet curable ink becomes high, which may cause ejection failure during inkjet printing. Further, if the content of the reactive monomer exceeds 85 parts by mass, other components necessary for curing the ink may be insufficient, which may result in poor curing.

Examples of the reactive oligomer used in the ultraviolet curable ink include urethane acrylate, polyester acrylate, epoxy acrylate, silicon acrylate, and polybutadiene acrylate, which may be used alone or in combination of two or more. Among them, urethane acrylate is preferable because of its excellent toughness, flexibility, and adhesiveness. Among urethane acrylates, aliphatic urethane acrylates composed of hydrocarbons are more preferable because they are resistant to yellowing.

It is also possible to mix and use the reactive monomer in advance with the reactive oligomer. The reactive monomer to be mixed is preferably bifunctional and/or trifunctional. When the reactive oligomer and the reactive monomer are mixed, the reactive monomer can be appropriately added to the extent that the performance of the reactive oligomer is not impaired.

The reactive oligomer is contained in 100 parts by mass of the ultraviolet curable ink in an amount of preferably 1 part by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 40 parts by mass or less, More preferably, it is in the range of 10 parts by mass or more and 30 parts by mass or less. By setting the content of the reactive oligomer within the above range, the cured film of the ultraviolet curable ink can have excellent toughness, flexibility and adhesion.

Examples of the photopolymerization initiator used in the ultraviolet curable ink include benzoins, benzyl ketals, aminoketones, titanocenes, bisimidazoles, hydroxyketones, and acylphosphine oxides, which may be used alone or in combination of two or more. It can be used in combination. Of these, hydroxyketones and acylphosphine oxides are preferable because they have high reactivity and are resistant to yellowing.

The content of the photopolymerization initiator is preferably in the range of 1 part by mass or more and 15 parts by mass or less and preferably in the range of 3 parts by mass or more and 10 parts by mass or less in 100 parts by mass of the ultraviolet curable ink. More preferable. If the content of the photopolymerization initiator is less than 1 part by mass, the polymerization may not proceed sufficiently and may be uncured. Further, if the content of the photopolymerization initiator exceeds 15 parts by mass, further improvement of the curing rate and the curing rate cannot be expected, resulting in an increase in cost.

If necessary, a dispersant may be added to the ultraviolet curable ink for the purpose of dispersing the pigment. Examples of the dispersant include anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, and polymeric dispersants, which may be used alone or in combination of two or more. be able to.

Further, if necessary, the ultraviolet curable ink, a sensitizer for promoting the initiation reaction of the photopolymerization initiator, a heat stabilizer, an antioxidant, a preservative, a defoaming agent, a penetrant, a resin binder, Various additives such as a resin emulsion, a reduction inhibitor, a leveling agent, a pH adjuster, a pigment derivative, a polymerization inhibitor, an ultraviolet absorber, and a light stabilizer can be added.

The ultraviolet curable ink is obtained by mixing the above-mentioned raw materials to be used, further dispersing the mixture using a disperser such as a roll mill, a ball mill, a colloid mill, a jet mill, or a bead mill, and then performing filtration. You can Among them, the bead mill is preferable because it can be dispersed in a large amount in a short time.

The viscosity of the ultraviolet curable ink at 50° C. is preferably in the range of 1 mPa·s or more and 20 mPa·s or less, more preferably 2 mPa·s or more and 15 mPa·s or less. When the viscosity is less than 1 mPa·s, it is difficult to adjust the ejection amount and the ejection of ink may become unstable. If the viscosity exceeds 20 mPa·s, ink may not be ejected.

The surface tension of the ultraviolet curable ink is more preferably in the range of 20 dyne/cm or more and 30 dyne/cm or less under the condition of 25°C. If the surface tension of the UV curable ink is less than 20 dyne/cm at 25° C., the wettability of the UV curable ink itself may be too good and the image may be blurred, and the ink may be supplied to the printer head. Becomes difficult. On the other hand, if the surface tension of the ultraviolet curable ink at 25° C. exceeds 30 dyne/cm, the ink may be repelled on the base material and the image may become unclear.

A wetting agent may be added to the ultraviolet curable ink in order to obtain the above-mentioned surface tension. Examples of the wetting agent to be used include a silicone type, an acrylic type, and a fluorine type. Among them, the silicone type and the fluorine type are preferable in terms of an excellent effect of lowering the surface tension.

The amount of the ultraviolet curable ink applied is preferably in the range of 1 g/m ² or more and 100 g/m ² or less, and more preferably in the range of 1 g/m ² or more and 50 g/m ² or less. When the applied amount is less than 1 g/m ² , sufficient image expression may be difficult, and further, the resulting inorganic decorative board may have poor water resistance. Further, when the applied amount exceeds 100 g/m ² , the applied ultraviolet curable ink may have poor curing.

In the inorganic decorative board 10 according to the present embodiment, the ink receiving ability of the ink receiving layer 1 is stable, and thus the color development of the ink layer 7 is good.

(2.4) Method of Manufacturing Inorganic Decorative Board The method of manufacturing the inorganic decorative board 10 according to the present embodiment includes a step of providing the ink receiving layer 1 and a step of providing the ink layer 7. The method for manufacturing the inorganic decorative board 10 may further include the step of providing the undercoat layer 8. Hereinafter, a case including the step of providing the undercoat layer 8 will be described.

First, in the step of providing the undercoat layer 8, the undercoat layer coating composition is applied onto the inorganic substrate 6 and dried.

Next, in the step of providing the ink receiving layer 1, the ink receiving layer coating composition is applied onto the inorganic base material 6 via the undercoat layer 8 and dried. A spray, a bar coater, a curtain flow coater, a roll coater and the like are used for coating the coating composition for the ink receiving layer. Specific examples of the spray include rotary spray and reciprocating spray.

The ink receiving layer 1 can be dried by hot air drying, blast drying, heater drying, hot plate drying, or the like. The drying conditions can be set appropriately, but for example, the drying temperature is 60 to 150° C. and the drying time is 0.5 to 30 minutes.

Next, in the step of providing the ink layer 7, inkjet printing is performed on the ink receiving layer 1. The thickness of the ink layer is preferably in the range of 1 μm or more and 150 μm or less. When the thickness of the ink layer 7 is 1 μm or more, it is possible to obtain a sufficient image expression, and further it is possible to suppress a decrease in water resistance of the inorganic decorative board 10. When the thickness of the ink layer 7 is 150 μm or less, generation of cracks can be suppressed.

The method of the inkjet printer used for inkjet printing is not particularly limited. For example, continuous methods such as charge modulation method, microdot method, charge injection control method and ink mist method, piezo method, pulse jet method, bubble jet method, and on-demand method such as electrostatic suction method. Can be used. Further specific examples of the inkjet printer include a serial type and a line type, and both can be used.

In this embodiment, the ink receiving layer 1 having a stable ink receiving ability can be formed by the step of providing the ink receiving layer 1. Further, by the step of providing the ink layer 7, it is possible to form the ink layer 7 having good color developability.

(3) Summary As is clear from the above embodiment, the present invention includes the following aspects. In the following, the reference numerals are given in parentheses only in order to clearly show the correspondence with the embodiment.

The coating composition for an ink receiving layer according to the first aspect is used for forming the ink receiving layer (1). The ink receiving layer coating composition contains a binder resin (3), inorganic particles (4) and resin beads (5). The content of the resin beads (5) is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin (3). The maximum particle size of the resin beads (5) is in the range of 0.1 times or more and 5 times or less the film thickness (T) of the ink receiving layer (1). The average particle diameter of the resin beads (5) is 0.5 times or more the film thickness (T) of the ink receiving layer (1).

According to this aspect, it is possible to suppress deterioration of the ink receiving ability and stabilize the color developability of the ink.

The ink-receiving layer coating composition according to the second aspect contains a binder resin (3), inorganic particles (4) and resin beads (5). The content of the inorganic particles (4) is in the range of 55 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin (3). The average particle diameter of the resin beads (5) is in the range of 10 μm or more and 60 μm or less. The content of the resin beads (5) is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin (3). Within the range of 10% or more and 40% or less, the ratio of the number of particles having a particle diameter of 10 μm or more and 50 μm or less to the total number of particles constituting the inorganic particles (4) and the resin beads (5) is there.

According to this aspect, it is possible to suppress deterioration of the ink receiving ability and stabilize the color developability of the ink.

In the ink-receiving layer coating composition according to the third aspect, in the first or second aspect, the inorganic particles (4) are aggregated particles (42).

According to this aspect, the aggregated particles (42) facilitate the capture of ink and the suppression of bleeding.

In the ink-receiving layer coating composition according to the fourth aspect, in any one of the first to third aspects, the breaking strength of the resin beads (5) is larger than the breaking strength of the inorganic particles (4).

According to this aspect, the resin beads (5) can prevent the inorganic particles (4) from being destroyed when the ink receiving layer coating composition is circulated by a pump.

The ink receiving layer (1) according to the fifth aspect is obtained by coating and drying the coating composition for an ink receiving layer according to any one of the first to fourth aspects.

According to this aspect, the ink receiving ability is stable even if there is a difference in the circulation time by the pump.

An inorganic decorative board (10) according to a sixth aspect includes an inorganic base material (6), an ink receiving layer (1) according to the fifth aspect provided on the inorganic base material (6), and the ink. An ink layer (7) provided on the receiving layer (1).

According to this aspect, since the ink receiving ability of the ink receiving layer (1) is stable, the color developability of the ink is stable, and the color development of the ink layer (7) is good.

A method for producing an inorganic decorative board (10) according to a seventh aspect is to apply the coating composition for an ink receiving layer according to any one of the first to fourth aspects onto an inorganic base material (6) and dry it. The method includes a step of providing an ink receiving layer (1) and a step of performing inkjet printing on the ink receiving layer (1) to provide an ink layer (7).

According to this aspect, the ink receiving layer (1) having a stable ink receiving ability can be formed, the color developability of the ink can be stabilized, and the ink layer (7) having a good color developability is formed. be able to.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples.

(1) Ink-Receptive Layer Coating Composition According to Table 1, a binder resin, inorganic particles, resin beads, a film-forming aid and water were mixed and stirred for 10 minutes to obtain an ink-receptive layer coating composition.

The binder resin used is as follows.
Acrylic-styrene emulsion (manufactured by BASF Japan Ltd., trade name “Acronal YJ2720D”, resin content 48.0%, Tg=9° C.)

The inorganic particles used are as follows.
・Calcium carbonate (Taiyo Kagaku Co., Ltd., trade name "Callite KT", pigment content 100%)

The resin beads used are as follows.
-Crosslinked PMMA fine particles (manufactured by Toyobo Co., Ltd., trade name "AR650S", average particle diameter 18 μm, transparent)
・Crosslinked PMMA fine particles (manufactured by Toyobo Co., Ltd., trade name “AR650SX”, average particle diameter 5 μm, transparent)
-Crosslinked PMMA fine particles (manufactured by Toyobo Co., Ltd., trade name "AR650MZ", average particle diameter 60 μm, transparent)
-Crosslinked acrylic beads (manufactured by Negami Kogyo Co., Ltd., trade name "SE-020T", average particle size 19 µm, white)
-Crosslinked acrylic beads (manufactured by Negami Kogyo Co., Ltd., trade name "SE-020T Kai" (without particles of "SE-020T" of more than 30 µm), average particle diameter 19 µm, white)

The film-forming aid used is as follows.
-2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (KH Neochem Co., Ltd., trade name "Kyowanol M")

(2) Inorganic decorative board (2.1) Circulation method In order to circulate the ink-receiving layer coating composition using an airless coating machine (small airless unit, manufactured by Anest Iwata Co., Ltd., trade name "ALS-333C") I have assembled the piping. Specifically, a stainless steel ball valve three-way valve was attached to the drain valve and connected to a paint discharge port with a pressure resistant hose so that the sucked paint composition for the ink receiving layer circulated in the pipe. The circulating ink-receiving layer coating composition can be discharged by opening the ball valve three-way valve. The volume of the coating composition for the ink receiving layer circulating in the pipe was 400 cm ³ , and it was circulated in 10 seconds per stroke.

(2.2) Sample Production Two types of samples of inorganic decorative boards were produced for each example and comparative example. The first is a sample (hereinafter also referred to as “first sample”) of an inorganic decorative board formed using the ink-receiving layer coating composition before being circulated. The second is a sample (hereinafter also referred to as "second sample") of an inorganic decorative board formed by using the ink receiving layer coating composition after being circulated. The first sample and the second sample were manufactured as follows.

<Ink receiving layer forming step>
A cement board was prepared as the inorganic base material 6. This inorganic base material 6 was placed in a badge dryer set at 100° C. and preheated. While the plate temperature of the inorganic base material 6 was 70 to 80° C., a white undercoat paint (enamel paint of acrylic emulsion) serving as a base was applied onto the inorganic base material 6 by airless spraying. Then, the inorganic base material 6 was put in a badge type dryer set at 130° C. and dried for 10 minutes. The film thickness of the undercoat layer 8 was 30 to 50 μm.

Next, the inorganic base material 6 on which the undercoat layer 8 was formed was put in a badge type dryer set at 130° C. and preheated. The ink receiving layer coating composition was applied onto the undercoat layer 8 of the inorganic base material 6 with a bar coater #24 or #48 while the plate temperature of the inorganic base material 6 was 60 to 70°C. After coating, it was dried with a hot air dryer. The drying conditions were a temperature of 80° C. and a time of 30 seconds. The thickness of the ink receiving layer 1 was 20 to 30 μm.

<Inkjet printing process>
After mixing according to the following formulation and dispersing using a bead mill dispersing machine, impurities were removed by filtration to prepare a uniform ultraviolet curable ink (black ink).

Black pigment: NIPEX35 2 parts by mass (CI Pigment BLACK 7, carbon black, manufactured by Orion Engineered Carbons Co., Ltd.)
Dispersant: SOLSPERSE33000 1.5 parts by mass (polymer dispersant, manufactured by ARKEMA)
Reactive oligomer: CN985B88 20 parts by mass (aliphatic urethane acrylate, bifunctional, manufactured by ARKEMA)
Reactive monomer: SR238F 70.8 parts by mass (1,6-hexanediol diacrylate, bifunctional, manufactured by ARKEMA)
Photoinitiator: Darocur 1173 5 parts by mass (2-hydroxy-2-methyl-1-phenyl-propan-1-one, manufactured by Ciba Specialty Chemicals Co., Ltd.)
Wetting agent: DOW CORNING TORAY 32 ADDITIVE
0.7 parts by mass (silicone wetting agent, manufactured by Toray Dow Corning Silicone Co., Ltd.)

The viscosity of the manufactured black ink was 8.5 mPa·s at 50° C., and the surface tension was 25.0 dyne/cm at 25° C.

Next, an ink jet printer was used to coat ink receiving layer 1 with SUMIVETA (K100%) under the following conditions to form ink layer 7.
◎Inkjet coating conditions a) Nozzle diameter: 40 (μm)
A) Applied voltage: 50 (V)
C) Pulse width: 15 (μs)
D) Driving frequency: 5 (kHz)
E) Resolution: 400 (dpi)
F) Head heating temperature: 60 (℃)
G) Ink application amount: 7 (g/m ² )
H) Substrate surface temperature: 40 (°C)

<UV curable ink curing process>
Then, the ultraviolet curable ink was cured under the following conditions to obtain a first sample and a second sample.
◎ UV irradiation conditions a) Lamp type: Metal halide lamp Output): 100 (W/cm)
I) Irradiation time: 0.5 (seconds)
E) Irradiation height: 50 (cm)
O) Timing from print to irradiation: 5 (seconds)

(3) Evaluation (3.1) Film-forming property With respect to the second sample, the surface of the ink-receiving layer was visually observed to evaluate the film-forming property based on the crack grade defined by JIS K5600-8-4. did.
○: Grade 0 to 1
X: Grade 2-5

(3.2) Color Difference For each of the first sample and the second sample, a lightness index L ^* was measured using a spectrocolorimeter (manufactured by Konica Minolta, Inc., trade name “CM-2600d”), The brightness difference ΔL ^* was determined.

Further, each sample was lined up and visually observed to confirm whether a color change was felt, and the color stability was evaluated according to the following criteria.
⊚ (ΔL ^* <1.0): No change in color is felt 〇 (1.0≦ΔL ^* <2.5): No change in color is noticeable × (ΔL ^* ≧2.5): Color Noticeable change

DESCRIPTION OF SYMBOLS 1 Ink receiving layer 3 Binder resin 4 Inorganic particles 42 Aggregated particles 5 Resin beads 6 Inorganic base material 7 Ink layer 10 Inorganic decorative board T Film thickness

Claims (7)

A coating composition for an ink receiving layer used for forming an ink receiving layer,
The ink-receiving layer coating composition contains a binder resin, inorganic particles and resin beads,
The content of the resin beads is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin,
The maximum particle diameter of the resin beads is within a range of 0.1 times or more and 5 times or less with respect to the thickness of the ink receiving layer,
The average particle diameter of the resin beads is 0.5 times or more the thickness of the ink receiving layer.
A coating composition for an ink receiving layer. A coating composition for an ink receiving layer,
The ink-receiving layer coating composition contains a binder resin, inorganic particles and resin beads,
The content of the inorganic particles is within the range of 55 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin,
The average particle diameter of the resin beads is in the range of 10 μm or more and 60 μm or less,
The content of the resin beads is in the range of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the solid content of the binder resin,
The ratio of the number of particles having a particle diameter of 10 μm or more and 50 μm or less to the total number of particles constituting the inorganic particles and the resin beads is 10% or more and 40% or less.
A coating composition for an ink receiving layer. The inorganic particles are agglomerated particles,
The ink-receiving layer coating composition according to claim 1 or 2. The breaking strength of the resin beads is larger than the breaking strength of the inorganic particles,
The ink-receiving layer coating composition according to claim 1. It is obtained by coating and drying the ink-receiving layer coating composition according to any one of claims 1 to 4.
Ink receiving layer. An inorganic substrate, an ink receiving layer according to claim 5 provided on the inorganic substrate, and an ink layer provided on the ink receiving layer,
Inorganic decorative board. A step of providing an ink receiving layer by coating the coating composition for an ink receiving layer according to any one of claims 1 to 4 on an inorganic substrate and drying;
A step of forming an ink layer by performing inkjet printing on the ink receiving layer.
Manufacturing method of inorganic decorative board.