JPWO2014034850A1 - Printing sheet, decorative sheet, and adhesive decorative sheet - Google Patents

Abstract

The present invention is a printing sheet for a lithographic printing plate comprising a plastic substrate and a curable resin layer laminated on at least one surface of the plastic substrate, wherein the curable resin layer is a curable resin layer. A resin and a pigment, wherein the pigment is an inorganic fine particle having an average particle diameter of 5 to 90 nm and whose surface is hydrophobized, and the film thickness of the curable resin layer is 0.1 to 15 μm. The present invention relates to a printing sheet. According to the present invention, a printing sheet excellent in blocking resistance, printability and transparency when printing using a lithographic printing plate, a decorative sheet and an adhesive decorative sheet obtained by printing the printing sheet Can be provided.

Description

The present invention relates to a printing sheet, a decorative sheet obtained by printing on the printing sheet, and an adhesive decorative sheet.
This invention claims priority based on Japanese Patent Application No. 2012-192200 for which it applied to Japan on August 31, 2012, and uses the content here.

A sheet (decoration sheet) that has been decorated by printing or the like may be attached to the surface of the molded product to impart design properties to the molded product or to protect the surface of the molded product.
In many cases, an anchor coat layer is formed on the surface of the sheet (printing sheet) before printing in order to improve adhesion to the printing layer.
However, when printing a printing sheet using a lithographic printing plate, if the anchor coat layer is formed, the printing sheet and the lithographic printing plate are likely to be in close contact (blocking), resulting in printing failure such as ink loss. Is likely to occur.

By the way, the printing sheet is usually continuously wound up in the state of a continuous belt-like sheet, and conveyed and stored as a roll.
However, even when the printing sheet on which the anchor coat layer is formed is wound up in a roll shape, the anchor coat layer and the sheet base material adjacent thereto are easily blocked, and as a result, it is difficult to pull out the roll-shaped printing sheet. There is a problem.

  Therefore, as a film in which the anchor coat layer and the sheet base material adjacent to the anchor coat layer are hardly adhered when the printing sheet is rolled up, for example, Patent Document 1 includes 0.1 to 5.0 μm. A laminated film roll in which a transparent film having an anchor coat layer containing inorganic particles having an average particle diameter on the surface is wound into a roll shape is disclosed. Patent Document 1 discloses that by adding inorganic particles to the anchor coat layer, the anchor coat layer has a surface roughness (Ra) of 0.015 to 0.060 μm, and can exhibit blocking resistance during winding. Has been.

JP 2010-253784 A

By the way, a decorating sheet may be stuck on optical members, such as a display and a touch panel, for example. Accordingly, the decorative sheet is also required to have excellent transparency.
However, with the laminated film roll described in Patent Document 1, sufficient transparency was not obtained.

  An object of the present invention is to provide a printing sheet excellent in blocking resistance, printability and transparency when printing using a lithographic printing plate, a decorative sheet and an adhesive decorative sheet obtained by printing the printing sheet. Is to provide.

The present invention has the following aspects.
[1] A printing sheet for printing using a lithographic printing plate, comprising a plastic substrate and a curable resin layer formed on the plastic substrate and containing a curable resin and a pigment. The sheet for printing, wherein the pigment is an inorganic fine particle having an average particle diameter of 5 to 90 nm, the surface of which is hydrophobized, and the film thickness of the curable resin layer is 0.1 to 15 μm.
[2] The printing sheet according to [1], wherein the arithmetic average roughness (Ra) of the surface of the curable resin layer measured in accordance with ASME B46.12 is 0.5 to 15 nm.
[3] A decorative sheet in which a printing layer is formed on the curable resin layer of the printing sheet according to [1] or [2].
[4] An adhesive decorative sheet in which an adhesive layer is formed on the surface of the decorative sheet according to [3] on the plastic substrate side.

That is, the present invention has the following aspects.
<1> A printing sheet for a lithographic printing plate comprising a plastic substrate and a curable resin layer laminated on at least one surface of the plastic substrate,
The curable resin layer contains a curable resin and a pigment, and the pigment has an average particle diameter of 5 to 90 nm, and the surface is an inorganic fine particle subjected to a hydrophobic treatment,
The printing sheet, wherein the curable resin layer has a thickness of 0.1 to 15 μm;
<2> The printing sheet according to <1>, wherein the arithmetic average roughness (Ra) of the surface of the curable resin layer measured in accordance with ASME B46.12 is 0.5 to 15 nm;
<3> A decorative sheet in which a printing layer is laminated on the curable resin layer of the printing sheet according to <1> or <2>;
<4> An adhesive decorative sheet in which an adhesive layer is laminated on at least one surface of the decorative sheet according to <3>.

  According to the present invention, a printing sheet excellent in blocking resistance, printability and transparency when printing using a lithographic printing plate, a decorative sheet and an adhesive decorative sheet obtained by printing the printing sheet Can provide.

It is sectional drawing which shows an example of the sheet | seat for printing. It is sectional drawing which shows the other example of the sheet | seat for printing. It is sectional drawing which shows the other example of the sheet | seat for printing. It is sectional drawing which shows an example of a decorating sheet. It is sectional drawing which shows an example of an adhesive decorating sheet. It is sectional drawing which shows the other example of an adhesive decorating sheet. It is sectional drawing which shows the other example of an adhesive decorating sheet. It is sectional drawing which shows the other example of an adhesive decorating sheet.

Hereinafter, the present invention will be described in detail.
[Printing sheet]
FIG. 1 is a cross-sectional view showing a configuration of a printing sheet according to an embodiment of the present invention.
The printing sheet 10 of this example includes a plastic substrate 11 and a curable resin layer 12 formed on the plastic substrate 11.
In one embodiment of the present invention, the thickness of the printing sheet is preferably 20 to 200 μm, more preferably 30 to 120 μm. The thickness can be measured using a stylus thickness meter (for example, ABS Digimatic Indicator ID-C112A with a peak hold function manufactured by Mitutoyo Corporation).

<Plastic substrate>
The plastic substrate 11 is not particularly limited as long as it has transparency, but the transparency of the plastic substrate 11 is such that the total light transmittance measured in accordance with JIS K 7361 is 85% or more. Is preferred. That is, in one embodiment of the present invention, the transparency of the plastic substrate 11 is determined by the parallel incidence of a test piece using a test piece of 100 mm × 100 mm and using CIE (International Commission on Illumination) standard light D65 as a light source. The total light transmittance defined as the ratio of the total transmitted light beam integrated by the integrating sphere to the light beam is preferably 85% or more. The total light transmittance is more preferably 85 to 95%, and still more preferably 88 to 92%.

Examples of the material of the plastic substrate 11 include polyethylene terephthalate (PET), polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene naphthalate, polyethylene, polypropylene, diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, and polychlorinated. Vinyl, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetherketone, polyethersulfone, polyetherimide, polyimide, fluororesin, polyamide, acrylic resin, etc. Can be mentioned.
Among these, PET is preferable from the viewpoints of transparency, weather resistance, solvent resistance, rigidity, cost, and the like.

Various additives may be included in the plastic substrate 11. Examples of the additive include antioxidants, heat stabilizers, ultraviolet absorbers, organic particles, inorganic particles, pigments, dyes, antistatic agents, nucleating agents, and coupling agents.
The plastic substrate 11 may be subjected to a surface treatment in order to improve adhesion with the curable resin layer 12. Examples of the surface treatment include an uneven surface treatment such as a sand blast treatment or a solvent treatment, a corona discharge treatment, a chromic acid treatment, a flame treatment, a hot air treatment, an ozone / ultraviolet irradiation treatment, or the like.
The thickness of the plastic substrate 11 is preferably 10 to 500 μm, and more preferably 20 to 300 μm. If the thickness of the plastic substrate 11 is 10 μm or more, the plastic substrate 11 is not easily broken, and if it is 500 μm or less, the transparency can be maintained well and the handleability is also excellent. Here, the “thickness of the plastic substrate 11” means that the plastic substrate 11 before the curable resin layer 12 is laminated is a stylus type film thickness meter (ABS Digimatic Indicator ID− with a peak hold function manufactured by Mitutoyo Corporation). It refers to the value measured using C112A).

<Curable resin layer>
The curable resin layer 12 includes a curable resin and a pigment, and is a layer provided on the outermost layer of the printing sheet 10. Here, the “curable resin layer” means a layer obtained by curing the curable resin. The “outermost layer” means a layer on the side of the printing sheet 10 that comes into contact with air.
As will be described in detail later, the curable resin layer 12 is obtained by, for example, applying a curable resin layer-forming composition containing a curable resin and a pigment to the plastic substrate 11 and drying and curing the coating film. . Hereinafter, each component which comprises the curable resin layer 12 is demonstrated.

(Pigment)
The pigment used for the curable resin layer 12 is inorganic fine particles (hereinafter, also referred to as “hydrophobized inorganic fine particles”) whose surfaces have been subjected to a hydrophobic treatment.
When a composition for forming a curable resin layer containing hydrophobized inorganic fine particles is applied onto the plastic substrate 11, the hydrophobized inorganic fine particles are partially exposed on the coating film surface, and the surface of the curable resin layer 12 is moderate. It becomes the surface (uneven surface 12a) which has unevenness. Therefore, even when printing is performed using a lithographic printing plate, the curable resin layer 12 is difficult to adhere to the lithographic printing plate and can exhibit blocking resistance. Therefore, the target printing can be performed on the printing sheet. Here, “the hydrophobic inorganic fine particles are partially exposed on the coating film surface” means that one inorganic fine particle is partially exposed on the coating film surface. That is, when the curable resin layer 12 includes hydrophobic inorganic fine particles having an average particle diameter of 5 to 90 nm, a part of the hydrophobic inorganic fine particles are applied without being embedded in the curable resin layer 12. Since it will be in the state exposed to the film | membrane surface, as a result, the printing sheet of this invention can express blocking resistance, and is preferable. Here, “the hydrophobic inorganic fine particles are buried in the curable resin layer 12” means that the entire hydrophobic inorganic fine particles are covered with the curable resin constituting the curable resin layer 12. To do.
Note that “blocking” in the present invention means that the lithographic printing plate and the curable resin layer of the printing sheet are in close contact when printing using the lithographic printing plate, and “blocking resistance” means this A property that relaxes adhesion.

  Hydrophobized inorganic fine particles are obtained by hydrophobizing the surface of inorganic fine particles. The method of hydrophobizing treatment is not particularly limited as long as it has the effect of the present invention, and a known method can be adopted. For example, a hydrophilic group on the surface of inorganic fine particles is reacted with a treating agent such as an organosilicon compound, and an alkyl group, etc. It is obtained by substituting with a hydrophobic group. That is, in one embodiment of the present invention, “hydrophobizing the surface of the inorganic fine particles” means substituting the hydrophilic group on the surface of the inorganic fine particles with a hydrophobic group such as an alkyl group.

  Examples of the inorganic fine particles include metal oxide fine particles such as silica, alumina, titania, zirconia, zinc oxide, germanium oxide, iridium oxide, and tin oxide; metal fluoride fine particles such as magnesium fluoride and sodium fluoride. . Further, metal fine particles, metal sulfide fine particles, metal nitride fine particles, and the like may be used. The preferred average particle size of the inorganic fine particles is the same as the preferred average particle size of the hydrophobic inorganic fine particles.

Examples of the hydrophobizing agent include organosilicon compounds.
Examples of the organosilicon compound include methyltrimethoxysilane, dimethyldimethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, tetraethoxysilane, phenyltriethoxysilane, and diphenyl. Examples include diethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane.
Moreover, fatty acid, alcohol, etc. can also be used as a processing agent. Specific examples include fatty acids having 2 or more carbon atoms and alcohols having 5 or more carbon atoms.

The average particle diameter of the hydrophobized inorganic fine particles is 5 to 90 nm, and preferably 20 to 60 nm.
If the average particle diameter of the hydrophobic inorganic fine particles is 5 nm or more, the hydrophobic inorganic fine particles are not buried in the curable resin layer 12, that is, the surface of the curable resin layer 12, that is, between the curable resin layer 12 and air. Since it is exposed on the interface, sufficient blocking resistance and printability can be obtained. Here, “printability” means that the ink adheres. On the other hand, if the average particle size of the hydrophobic inorganic fine particles is 90 nm or less, light scattering is reduced. In addition, since it is possible to suppress the unevenness of the surface of the curable resin layer 12 from becoming too large, defects such as dents are less likely to occur when the printing sheet 10 is wound up. Therefore, blocking resistance can be imparted without impairing the transparency of the curable resin layer 12.
In addition, it is difficult to produce particles having an average particle diameter of less than 5 nm, and advanced techniques are required. In addition, since it is easy to aggregate and form secondary particles, it is inferior in handleability.

The average particle size of the hydrophobic inorganic fine particles is the average particle size of primary particles of the hydrophobic inorganic fine particles. Here, the “primary particles” are basic crystal particles constituting the inorganic fine particles, and the primary particles aggregated into a bulk are called secondary particles. In one embodiment of the present invention, the inorganic fine particles contained in the curable resin layer 12 are preferably primary particles, not bulk particles. If the inorganic fine particles are primary particles, blocking resistance and transparency can be obtained, which is preferable.
In addition, the average particle diameter in the present invention is a value measured by an observation image of a transmission electron microscope or a scanning electron microscope. Specifically, the average particle size of the hydrophobic inorganic fine particles is measured as follows.
Using a transmission electron microscope or a scanning electron microscope, the maximum length of the particle image of hydrophobic inorganic fine particles (Dmax: the maximum length at two points on the contour of the particle image) and the maximum vertical length (DV-max: Measure the length of the particle image between the two straight lines parallel to the maximum length and measure the geometric mean value (Dmax × DV-max) ^1/2 . The diameter. With this method, the particle diameter of 100 arbitrary inorganic fine particles is measured, and the arithmetic average value is taken as the average particle diameter.
In the present invention, the inorganic fine particles are preferably primary particles. As a method for discriminating primary particles, from the observation image of a transmission electron microscope or a scanning electron microscope, a primary particle or a plurality of particles in which inorganic fine particles are present alone in a curable resin layer are gathered. The existing particles are defined as secondary particles.

The content of the hydrophobic inorganic fine particles in the curable resin layer 12 is preferably 3 to 15 parts by mass and more preferably 5 to 12 parts by mass in 100 parts by mass of the curable resin. When the content of the hydrophobized inorganic fine particles is 3 parts by mass or more, the printing sheet 10 having excellent blocking resistance can be obtained.
On the other hand, when the content of the hydrophobized inorganic fine particles is 15 parts by mass or less, the curable resin layer 12 having better blocking resistance can be formed while maintaining appropriate transparency.

  In one embodiment of the present invention, it is preferable that the pigment does not include inorganic fine particles (hydrophilic inorganic fine particles) whose surface is not hydrophobized, and is composed of only hydrophobic inorganic fine particles. If the pigment is composed only of the hydrophobic inorganic fine particles, a printing sheet that is superior in blocking resistance and transparency can be obtained.

(Curing resin)
Examples of the curable resin contained in the curable resin layer 12 include a thermosetting resin and an active energy ray curable resin.
Examples of the thermosetting resin include phenol resin, urea resin, diallyl phthalate resin, melamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, amino alkyd resin, silicon resin, polysiloxane resin, and the like.

As the active energy ray-curable resin, a urethane acrylate oligomer is preferable.
The urethane acrylate oligomer is one in which a polyoxyalkylene segment having 2 to 10 carbon atoms or a saturated polyester segment having 2 to 10 carbon atoms or both are connected via a urethane bond, and has an acryloyl group at both ends. Further, the urethane acrylate oligomer preferably has a mass average molecular weight (Mw) of 10,000 to 300,000, and more preferably has a Mw of 30,000 to 200,000. Here, Mw refers to a value measured using gel permeation chromatography (GPC).

  Moreover, in order to give the function of a hard-coat layer to the curable resin layer 12, it is preferable to use the polymer obtained by polymerizing a polyfunctional (meth) acryl monomer as an active energy ray curable resin. Since such a polymer is a hard acrylic polymer having a crosslinked structure, it is excellent in surface hardness, transparency, scratch resistance and the like.

“Polyfunctional” means having two or more polymerizable unsaturated groups in the molecule, and “(meth) acrylic monomer” is a compound having at least a (meth) acryloyl group as a polymerizable unsaturated group. . “(Meth) acryloyl group” means an acryloyl group or a methacryloyl group.
Examples of the polyfunctional (meth) acrylic monomer include the following monomers.
Dipropylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol (mass average molecular weight 600) di (meth) acrylate, propylene oxide modified neopentyl glycol Bifunctional (meth) acrylates such as di (meth) acrylate, modified bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, polyethylene glycol (mass average molecular weight 400) di (meth) acrylate;
Trifunctional (meth) acrylates such as pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, polyether tri (meth) acrylate, glycerin propoxytri (meth) acrylate, etc. ;
Tetrafunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate;
5 or more functional (meth) acrylates such as dipentaerythritol penta (meth) acrylate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. etc.
These polyfunctional (meth) acrylic monomers may be used individually by 1 type, and may use 2 or more types together.

The polyfunctional (meth) acrylic monomer is mainly composed of a tetrafunctional or higher functional (meth) acrylic monomer (preferably a pentafunctional or higher functional (meth) acrylic monomer) and a 2-3 functional (meth) acrylic monomer as a subcomponent. It is preferable that Here, the “main component” means a component contained in 51 to 100 parts by mass in 100 parts by mass of the polyfunctional (meth) acrylic monomer. The “subcomponent” means a component contained in 0 to 49 parts by mass in 100 parts by mass of the polyfunctional (meth) acrylic monomer. That is, the proportion of the tetrafunctional or higher (meth) acrylic monomer is preferably 50 parts by mass or more and less than 95 parts by mass and more preferably 60 parts by mass or more and less than 90 parts by mass in 100 parts by mass of the polyfunctional (meth) acrylic monomer. preferable. Further, the proportion of the 2-3 functional (meth) acrylic monomer is preferably 5 parts by weight or more and less than 50 parts by weight, more preferably 10 parts by weight or more and less than 40 parts by weight, in 100 parts by weight of the polyfunctional (meth) acrylic monomer. preferable.
Among these, a tetra- or higher functional (meth) acrylic monomer contributes to an improvement in hardness, and a 2-3 functional (meth) acrylic monomer contributes to an improvement in the flexibility of the cured resin. Therefore, as a curable resin, the tetrafunctional (meth) acrylic monomer is contained in an amount of 50 parts by mass or more and less than 95 parts by mass in 100 parts by mass of the polyfunctional (meth) acrylic monomer. When the meth) acrylic monomer is contained in 5 parts by mass or more and less than 50 parts by mass in 100 parts by mass of the polyfunctional (meth) acrylic monomer, the resulting curable resin layer 12 has high hardness and moderate flexibility. As will be described later in detail, the curable resin layer 12 can be a hard coat layer.

  The content of the curable resin in the curable resin layer 12 is preferably 82 to 97 parts by mass, and 87 to 92 parts by mass in 100 parts by mass of the solid content of the curable resin layer forming composition. It is more preferable. If the content of the curable resin is 82 parts by mass or more, sufficient adhesion to the plastic substrate 11 can be secured. In addition, when a polymer obtained by polymerizing a polyfunctional (meth) acrylic monomer is used as the curable resin, sufficient hard coat performance is easily obtained. On the other hand, if the content of the curable resin is 97% by mass or less, an auxiliary agent such as a photopolymerization initiator or a leveling agent can be added as an optional component, and curing failure hardly occurs. This is preferable because the coating suitability of the resin layer forming composition can be easily maintained. Here, “sufficient hard coat performance” means superior scratch resistance than a plastic substrate.

(Other ingredients)
The curable resin layer forming composition preferably contains a photopolymerization initiator together with the polyfunctional (meth) acrylic monomer in order to promote curing.
Known photopolymerization initiators can be used such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4 4'-diethylaminobenzophenone, propiophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, Examples include 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate. These photoinitiators may be used individually by 1 type, and may be used in combination of 2 or more type.
0.5-10 mass parts is preferable in the solid content of 100 mass parts of the composition for curable resin layer formation, and, as for the compounding quantity of a photoinitiator, 2-8 mass parts is more preferable. Since it is hard to produce the hardening defect of the curable resin layer 12 as it is 0.5 mass part or more, it is preferable. Further, even if the photopolymerization initiator is blended in an amount exceeding 10% by mass with respect to the total mass of the solid content of the composition for forming a curable resin layer, a curing accelerating effect corresponding to the blending amount cannot be obtained, and the cost is reduced. Also gets higher. In addition, the photopolymerization initiator may remain in the curable resin layer 12 to cause yellowing or bleeding out.

  In addition to the photopolymerization initiator, a photosensitizer can be further contained. Examples of the photosensitizer include n-butylamine, triethylamine, and tri-n-butylphosphine.

  The composition for curable resin layer formation may contain other components other than the above as long as the effects of the present invention are not impaired. For example, a known additive used for imparting other functions (antibacterial properties, antifouling properties, antistatic properties, ultraviolet shielding properties, etc.) other than blocking resistance to the curable resin layer may be included. it can. Examples of such additives include an antibacterial agent for imparting antibacterial properties; a fluorine-based antifouling agent for imparting antifouling properties; a fluorine-based lubricant for imparting slipperiness; and improving coating suitability Leveling agent for imparting anti-static properties: metal oxide fine particles for imparting antistatic performance, antistatic resin, conductive polymer; metal oxide fine particles for imparting ultraviolet shielding properties, ultraviolet absorbers; light stabilizers, etc. Is mentioned.

The curable resin layer forming composition may contain a solvent.
Examples of the solvent include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, cyclohexanone, ethyl acetate, butyl acetate, propylene glycol monomethyl. Ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone and the like are used. These may be used alone or in combination of two or more.
In particular, since it is possible to reduce coating unevenness, it is preferable to use two or more solvents having different evaporation rates in combination. For example, it is preferable to use a mixture of at least two selected from methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether.

(Function of curable resin layer)
The curable resin layer 12 plays a role of improving adhesion between the printed layer and the curable resin layer 12 when a printing layer is formed on the curable resin layer 12 of the printing sheet 10 using a lithographic printing plate. . Moreover, it can be set as the curable resin layer 12 which has the function of the hard-coat layer depending on the kind and content of curable resin.
When the curable resin layer 12 also has a function of a hard coat layer, the printing sheet 10 can be used as a hard coat sheet.

(Film thickness of curable resin layer)
The film thickness of the curable resin layer 12 can be adjusted in the range of 0.1 to 15 μm.
In one embodiment of the present invention, the film thickness of the curable resin layer 12 is the average value of the thickness from the interface between the curable resin layer 12 and the plastic substrate 11 to the interface between the curable resin layer 12 and air. Means that. The film thickness can be obtained by measuring in a wavelength range of 380 to 1050 nm using a non-contact film thickness meter (F20 manufactured by Filmmetrics). Moreover, 0.6-12 micrometers is preferable and, as for the film thickness of the curable resin layer 12, 1-10 micrometers is more preferable. Blocking resistance falls that the film thickness of the curable resin layer 12 is less than 0.1 micrometer. Further, the function of the curable resin layer 12 is not exhibited, and when printing is performed on the printing sheet 10, that is, when the printing layer is laminated on the curable resin layer 12, the printing with the curable resin layer 12 is performed. Adhesion with the layer decreases. On the other hand, when the film thickness of the curable resin layer 12 exceeds 15 μm, the transparency of the curable resin layer itself decreases. In addition, when printing is performed on the printing sheet 10, that is, when a printing layer is laminated on the curable resin layer 12, the adhesion between the curable resin layer 12 and the printing layer is lowered.

<Physical properties>
The arithmetic average roughness (Ra) measured according to ASME B46.12 on the surface of the curable resin layer 12 (that is, the surface of the printing sheet 10) is preferably 0.5 to 15 nm, and preferably 1 to 10 nm. More preferred. Ra is an index representing the surface state of the curable resin layer 12. If Ra is within the above range, the hydrophobic inorganic fine particles are exposed on the surface of the curable resin layer 12, and the surface of the curable resin layer 12 is It means that the surface has moderate irregularities (irregularities 12a). In particular, if Ra on the surface of the curable resin layer 12 containing hydrophobic inorganic fine particles is 0.5 nm or more, sufficient blocking resistance and printability can be obtained. On the other hand, if Ra on the surface of the curable resin layer 12 is 15 nm or less, the transparency of the printing sheet 10 can be maintained well.

Ra described above has a measurement area of 10 μm using a scanning probe microscope having a radius of curvature of 8 nm, a spring constant of 42 N / m, a resonance frequency of 320 kHz, and a material of single crystal Si in accordance with ASME B46.12. By capturing an image as 10 μm and processing the obtained image, Ra on the film surface can be calculated. As the probe, it is preferable to use a Si single crystal probe.
The image processing may be realized by image processing means connected to the scanning probe microscope. The image processing means may include a memory and a central processing unit (CPU). Specifically, using a scanning probe microscope (Neoscope IV and Nanoscope IIIa manufactured by Veeco), an Si single crystal probe is used as a probe, a measurement mode is set to Taping mode, and an image is captured with a measurement area of 10 μm × 10 μm. . After the obtained image is subjected to Flatten processing (0th order) and Planefit processing (XY) once as image processing for removing swell using the analysis software attached to the scanning probe microscope. It is preferable to calculate the surface roughness.

  Ra of the surface of the curable resin layer 12 can be adjusted by, for example, the average particle diameter or the added amount of the hydrophobic inorganic fine particles contained in the curable resin layer 12. Specifically, Ra tends to increase as the average particle size of the hydrophobized inorganic fine particles increases, and as the amount of the hydrophobized inorganic fine particles increases, the smaller the average particle size of the hydrophobized inorganic fine particles, Ra tends to decrease as the amount of the hydrophobic inorganic fine particles added decreases.

  The haze value of the printing sheet 10 is preferably 1% or less, and the total light transmittance is preferably 87% or more. If the haze value and the total light transmittance are within the above ranges, the printing sheet 10 can be suitably used as an optical application.

The haze value is a value measured according to JIS K 7136, and the total light transmittance is a value measured according to JIS K 7361. That is, in one aspect of the present invention, the haze value of the printing sheet 10 is obtained by scattering out of the transmitted light that passes through the test piece using the CIE standard light D65 as a light source, using a sample of 100 mm × 100 mm. It can be measured by a method defined as the percentage of transmitted light that deviates 0.044 rad (2.5 degrees) or more from incident light. The haze value is preferably 1.0% or less, and more preferably 0.8% or less. Further, the total light transmittance of the printing sheet 10 is a ratio of the total transmitted light beam integrated by the integrating sphere with respect to the parallel incident light beam of the test piece using the CIE standard light D65 as a light source using a sample of 100 mm × 100 mm. It can be measured by a defined method. The total light transmittance is preferably 87% or more, and more preferably 89% or more.
The haze value and total light transmittance of the printing sheet 10 are determined based on the type of resin constituting the plastic substrate 11, the type of curable resin constituting the curable resin layer 12, and the Ra of the surface of the curable resin layer 12. Can be adjusted by.

<Method for producing printing sheet>
The printing sheet 10 can be manufactured as follows, for example.
First, a hydrophobic inorganic fine particle as a pigment, a curable resin, a solvent, and other components as necessary are mixed to prepare a composition for forming a curable resin layer. As solid content concentration of the composition for curable resin layer formation, it is preferable that it is 10-60 mass% with respect to the total mass of the composition for curable resin layer formation, and it is 20-50 mass%. More preferred.
Next, the printing sheet 10 in which the curable resin layer 12 is formed on the plastic substrate 11 is obtained by coating the plastic substrate 11 with the curable resin layer forming composition and drying and curing the coating film. It is done.
That is, in one embodiment of the present invention, a method for producing a printing sheet includes a step of preparing a curable resin layer forming composition, and a curable resin layer forming composition obtained in the above step. And a step of coating the material to obtain a printing sheet in which a curable resin layer is laminated on a plastic substrate.

Examples of the coating method of the curable resin layer forming composition include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and printing. The method using a machine etc. is mentioned.
The coating amount of the curable resin layer forming composition is appropriately set according to the thickness of the curable resin layer 12 to be formed.

When the curable resin is an active energy ray curable resin, the coating can be cured by irradiation with active energy rays. When the curable resin is a thermosetting resin, a heating furnace, an infrared lamp, etc. It can be cured by heating with As heating conditions, it is preferable to carry out at 60-100 degreeC for 1 to 5 minutes, and it is more preferable to carry out at 70-90 degreeC for 2 to 3 minutes.
Examples of the active energy rays include ionizing radiation such as ultraviolet rays, electron beams, visible rays, and γ rays. Among them, ultraviolet rays are preferable from the viewpoint of versatility. As the ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like can be used.
As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as a cockloftwald type, a bandecraft type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type can be used.
Curing by irradiation with active energy rays is preferably performed in the presence of an inert gas such as nitrogen. The irradiation amount of the active energy ray is preferably 100~1000mJ / cm ^2, more preferably 150~500mJ / cm ^2.
Curing may be performed in one stage, or may be performed in two stages, a preliminary curing process and a main curing process.

<Effect>
Since the curable resin layer 12 containing the hydrophobic inorganic fine particles is formed on the plastic substrate 11, the printing sheet 10 of the present embodiment described above is excellent in blocking resistance. Therefore, when printing, a printing layer can be formed on the surface of the curable resin layer 12 without blocking the printing sheet and the planographic printing plate. The reason is considered as follows.
The printing surface of the printing sheet 10, that is, the surface of the curable resin layer 12 is an uneven surface 12 a because the hydrophobic inorganic fine particles are partially exposed. By having this unevenness, it is considered that the contact area between the curable resin layer 12 and the lithographic printing plate is reduced, and the blocking resistance is improved.

If hydrophilic inorganic fine particles are used instead of the hydrophobic inorganic fine particles, an appropriate uneven surface cannot be obtained when a curable resin layer is formed, and sufficient blocking resistance and transparency cannot be obtained. The reason is considered as follows.
When hydrophilic inorganic fine particles are added to the curable resin layer forming composition, the hydrophilic inorganic fine particles aggregate and settle in the curable resin layer forming composition, and good dispersibility cannot be obtained. Therefore, when a coating film is formed by applying the composition for forming a curable resin layer containing only the hydrophilic inorganic fine particles, an appropriate uneven surface cannot be obtained, that is, in accordance with the aforementioned ASME B46.12. The measured Ra does not become a value of 0.5 to 15 nm, and the hydrophilic inorganic fine particles are not uniformly dispersed in the curable resin layer 12. In addition, even when hydrophilic inorganic fine particles are well dispersed in the composition for forming a curable resin layer, the particles are aggregated to form secondary particles during the coating process, and the average particle size increases. Accordingly, a moderate uneven surface cannot be obtained, and the hydrophilic inorganic fine particles are not uniformly dispersed in the curable resin layer 12. Therefore, it is considered that sufficient blocking resistance and transparency cannot be obtained even when hydrophilic inorganic fine particles are used as the pigment.
Moreover, in order to develop sufficient blocking resistance with hydrophilic inorganic fine particles having poor dispersibility as described above, a larger amount of addition is required than with hydrophobic inorganic fine particles, but the transparency of the curable resin layer is high. It becomes insufficient. In addition, the unevenness of the surface of the curable resin layer becomes large, which is considered to cause defects such as dents when the printing sheet is wound. In addition, it is thought that the unevenness | corrugation of the surface of a curable resin layer becomes remarkable not only when using hydrophilic inorganic fine particles but as the average particle diameter of particle | grains becomes large.

On the other hand, the present invention is characterized by using hydrophobic inorganic fine particles as a pigment. Since the hydrophobic inorganic fine particles have a small surface energy, the interaction between the fine particles becomes small. As a result, the hydrophobic inorganic fine particles hardly aggregate with each other and are excellent in dispersibility in the composition for forming a curable resin layer. In addition, by using hydrophobic inorganic fine particles having an average particle size of 90 nm or less, light scattering is reduced, and the printing sheet 10 having excellent transparency and blocking resistance can be obtained.
In the present invention, all of the pigments contained in the curable resin layer 12 are preferably hydrophobic inorganic fine particles, but may contain hydrophilic inorganic fine particles as long as the effects of the present invention are not impaired.
In addition, if the average particle size is hydrophobic inorganic fine particles of 90 nm or less, the unevenness of the surface of the curable resin layer 12 becomes too large, that is, Ra measured in accordance with ASME B46.12 is larger than 15 nm. Can be suppressed. Therefore, the printing sheet 10 excellent in transparency without a defect such as a dent at the time of winding can be obtained.

<Application>
The printing sheet 10 can be printed with a lithographic printing plate. That is, a printing layer can be formed on the curable resin layer 12 and used as a material for forming a decorative sheet. In particular, if the curable resin layer 12 has the function of a hard coat layer, it can also be used as a hard coat sheet. A printing method using a lithographic printing plate using the printing sheet 10, that is, a method for producing a decorative sheet according to the present invention will be described later.

<Another embodiment>
The printing sheet of the present invention is not limited to that shown in FIG. For example, as shown in FIG. 2, an easy adhesion layer 13 may be provided between the plastic substrate 11 and the curable resin layer 12.

  1 and 2, the curable resin layer 12 is formed on one side of the plastic substrate 11, but for example, as shown in FIG. A resin layer 12 may be formed.

[Decorative sheet]
FIG. 4 is a cross-sectional view showing a configuration of a decorative sheet as an embodiment of the present invention.
In the decorative sheet 20 of this example, a printing layer 21 is laminated on the curable resin layer 12 of the printing sheet 10 shown in FIG.

<Print layer>
The print layer 21 is mainly applied for decoration or the like.
Examples of the printing layer 21 include a layer in which a pattern, characters, a photograph, and the like are printed with printing ink. As shown in FIG. 4, the print layer 21 may be formed on the entire surface of the curable resin layer 12, or may be formed on a part of the surface of the curable resin layer 12.
The printing layer 21 includes, for example, a colorant (pigment, dye) and a binder (polyvinyl resin, polyamide resin, polyacrylic resin, polyurethane resin, polyvinyl acetal resin, polyester urethane resin, cellulose ester resin, alkyd. It is possible to form by printing a colored ink containing a resin. In the case of forming a metal color, metal particles such as aluminum, titanium and bronze, and a pearl pigment obtained by coating mica with titanium oxide can be used. That is, it is preferable that the printing layer 21 includes a colorant and a binder.
The film thickness of the printing layer 21, that is, the distance from the interface of the curable resin layer 12 to the outermost surface of the printing layer 21 (interface with air) in FIG. 4 is preferably 5 to 50 μm, more preferably 10 to 40 μm. preferable. The film thickness can be specifically measured using a stylus type film thickness meter (ABS Digimatic Indicator ID-C112A with a peak hold function manufactured by Mitutoyo Corporation).

<Method for producing decorative sheet>
The decorative sheet 20 is obtained by printing (lithographic printing) the printing sheet 10 using a lithographic printing plate (lithographic plate). Specifically, printing is performed by bringing the planographic printing plate and the curable resin layer 12 of the printing sheet 10 into contact with each other, and the printing layer 21 is formed on the curable resin layer 12.
The material of the lithographic printing plate is not particularly limited as long as it has the effects of the present invention, and may be metal, plastic, or glass. The printing sheet 10 of the present invention is particularly suitable for lithographic printing using a metal lithographic printing plate.

<Effect>
The decorative sheet 20 of the present embodiment described above is obtained by printing the printing sheet 10 of the present invention. Since the printing sheet 10 of the present invention is excellent in blocking resistance and printability, the target printing layer 21 can be formed on the curable resin layer 12 even when printing using a lithographic printing plate.
Moreover, since the printing sheet 10 of this invention is excellent in transparency, the decorating sheet 20 using this is also excellent in transparency.

<Application>
The decorative sheet 20 is used by being attached to the surface of a molded product (adhered body). In particular, if the curable resin layer 12 has the function of a hard coat layer, it can also be used as a hard coat sheet.

[Adhesive decorative sheet]
In one aspect of the present invention, the adhesive decorative sheet has an adhesive layer laminated on at least one surface of the decorative sheet.
That is, in one aspect of the present invention, the adhesive decorative sheet includes a plastic substrate, a curable resin layer laminated on at least one surface of the plastic substrate, a printed layer, and an adhesive layer. The plastic substrate is laminated on the adhesive layer, a curable resin layer is laminated on the plastic substrate, and a printing layer is further laminated on the curable resin layer, or the plastic It is preferable that the curable resin layer is laminated on a substrate, the printed layer is laminated on the curable resin layer, and the adhesive layer is further laminated on the printed layer.
FIG. 5 is a cross-sectional view showing a configuration of an adhesive decorative sheet which is an embodiment of the present invention.
In the adhesive decorative sheet 30 of this example, an adhesive layer 31 and a release sheet 32 are provided in this order on the surface of the decorative sheet 20 shown in FIG. 4 on the plastic substrate 11 side.
That is, in another aspect of the present invention, the adhesive decorative sheet includes a plastic substrate, a curable resin layer laminated on at least one surface of the plastic substrate, a printed layer, an adhesive layer, and a release layer. It is preferable to include a sheet.

<Adhesive layer>
The adhesive layer 31 is a layer for adhering the decorative sheet 20 to an adherend.
It is preferable that the adhesion layer 31 is comprised with the adhesive. Examples of the pressure-sensitive adhesive include natural rubber-based pressure-sensitive adhesives, synthetic rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. Moreover, any of solvent system, emulsion system, and water system may be sufficient. Among these, acrylic solvent-based pressure-sensitive adhesives are particularly preferable from the viewpoints of transparency, weather resistance, durability, cost and the like when used for optical system applications.
Other auxiliary agents may be added to the adhesive as necessary. Other auxiliary agents include thickeners, pH adjusters, tackifiers, binders, crosslinking agents, adhesive fine particles, antifoaming agents, antiseptic / antifungal agents, pigments, inorganic fillers, stabilizers, wetting agents, wetting agents. Etc.
The thickness of the adhesive layer 31 is preferably 3 to 500 μm, more preferably 4 to 300 μm, and still more preferably 5 to 150 μm. When the film thickness of the adhesive layer 31 is less than 3 μm, it is difficult to control the film thickness, and unevenness tends to occur. On the other hand, when the film thickness of the adhesive layer 31 exceeds 500 μm, problems may occur in the manufacturing process such as drying and curing. In addition, problems such as paste sticking out may occur in post-processing such as punching. Here, the film thickness of the pressure-sensitive adhesive layer 31 refers to the distance from the interface between the pressure-sensitive adhesive layer 31 and the easy-adhesion layer 33 to the interface between the pressure-sensitive adhesive layer 31 and the release sheet 32 in the embodiment of FIG. Moreover, in the aspect of FIG. 7, the distance from the interface of the adhesion layer 31 and the printing layer 21 to the interface to the adhesion layer 31 and the peeling sheet 32 is pointed out. The thickness of the adhesive layer 31 can be measured using a stylus type film thickness meter (ABS Digimatic Indicator ID-C112A with a peak hold function manufactured by Mitutoyo Corporation).

As release sheet 32, what has the base material for release sheets and the release agent layer provided in the adhesion layer 31 side of the base material for release sheets is mentioned, for example.
Examples of the release sheet substrate include paper such as high-quality paper and glassine paper, and plastic films such as polyethylene terephthalate film and polypropylene film.
As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
The thickness of the release sheet 32 is preferably 20 to 100 μm.

<Method for producing adhesive decorative sheet>
The adhesive decorating sheet 30 is, for example, coated with an adhesive on the surface of the decorating sheet 20 on the side of the plastic substrate 11 (hereinafter, this surface is also referred to as “the back side of the decorating sheet”), and the adhesive layer 31. And a release sheet 32 is stuck on the adhesive layer 31. Alternatively, an adhesive may be applied on the release sheet 32 to form the adhesive layer 31, and the adhesive layer 31 and the back surface of the decorative sheet 20 may be adhered to produce the adhesive decorative sheet 30. .
Examples of the method for applying the pressure-sensitive adhesive include the various coating methods exemplified above in the description of the method for producing a printing sheet.

In the above-described method, the adhesive sheet 31 and the release sheet 32 are formed on the surface of the plastic substrate 11 after printing the printing sheet 10 to obtain the decorative sheet 20. The manufacturing method is not limited to the method described above.
For example, before printing, the adhesive layer 31 and the release sheet 32 are formed in advance on the surface of the printing sheet 10 on the plastic substrate 11 side, and the printing layer is formed on the curable resin layer 12 of the printing sheet with the adhesive layer. 21 may be formed to produce the adhesive decorative sheet 30.

<How to use>
When using the decorative sheet 20, the release sheet 32 of the adhesive decorative sheet 30 is peeled off to expose the adhesive layer 31, and the adhesive layer 31 is attached to an adherend (for example, the surface of a display or a touch panel). To do.

<Effect>
Since the adhesive layer 31 is formed on the surface on the plastic substrate 11 side of the decorative sheet 20 of the present invention, the adhesive decorative sheet 30 of the present embodiment described above has the decorative sheet 20 of the present invention. Can be attached to an adherend.
Moreover, since the peeling sheet 32 is provided on the adhesion layer 31, the adhesive decorating sheet 30 shown in FIG. 5 is stored and transported by being wound into a roll or the like until the decorating sheet 20 is used. It is possible.

<Another embodiment>
The adhesive decorative sheet of the present invention is not limited to that shown in FIG. For example, as shown in FIG. 6, an easy adhesion layer 33 may be provided between the plastic substrate 11 and the adhesive layer 31. For example, as illustrated in FIG. 7, an adhesive layer 31 and a release sheet 32 may be provided on the print layer 21. For example, as shown in FIG. 8, the adhesion layer 31 and the peeling sheet 32 may be provided in both surfaces of the adhesive decorating sheet.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.

[Pigment]
The following colloidal silicas A to E were used as pigments.
Colloidal silica A: Silica methyl isobutyl ketone dispersion having a hydrophobic surface (CIK Nanotech, solid content 30% by mass, average particle size 30 nm).
Colloidal silica B: Methyl isobutyl ketone dispersion of silica whose surface has been subjected to a hydrophobic treatment (manufactured by Nissan Chemical Industries, Ltd., solid content: 30% by mass, average particle size: 10 nm).
Colloidal silica C: Silica methyl ethyl ketone dispersion with a hydrophobic surface (manufactured by Nissan Chemical Industries, solid content 30% by mass, average particle size 70 nm).
Colloidal silica D: A methyl isobutyl ketone dispersion of silica whose surface is not hydrophobized (manufactured by CIK Nanotech, solid content 30% by mass, average particle size 30 nm).
Colloidal silica E: Silica methyl isobutyl ketone dispersion having a hydrophobic surface (CIK Nanotech, solid content 15% by mass, average particle size 100 nm).
The silica whose surface has been hydrophobized, that is, colloidal silica A, B, C, E corresponds to the hydrophobized inorganic fine particles, and the colloidal silica D whose surface has not been hydrophobized corresponds to the hydrophilic inorganic fine particles.

[Example 1]
<Preparation of curable resin layer forming composition>
100 parts by mass of urethane acrylate oligomer (trade name Art Resin UN-905, manufactured by Negami Kogyo Co., Ltd., mass average molecular weight 40,000 to 200,000, solid content 70% by mass, solvent toluene) as a curable resin, and colloidal as a pigment 12 parts by mass of silica A and 3 parts by mass of a photopolymerization initiator (trade name IRGACURE184, manufactured by BASF) were mixed to prepare a curable resin layer forming composition.
Table 1 shows the composition of the curable resin layer forming composition. In addition, the compounding quantity (content) of curable resin, a pigment, and a photoinitiator which are shown in Table 1 is the quantity (mass part) converted into solid content.

<Manufacture of printing sheets>
A PET film (trade name Lumirror U48, manufactured by Toray Industries, Inc., 21 cm × 29.7 cm, thickness 75 μm) is used as a plastic substrate, and the composition for forming a curable resin layer obtained on the plastic substrate is coated with a bar. Worked. Then, at 80 ° C. in a hot air drier and dried for 60 seconds, further with a high pressure mercury lamp UV irradiation apparatus (manufactured by Eye Graphics Co., Ltd.), irradiation intensity 200 mW / cm ^2, UV under conditions of integrated quantity of light 300 mJ / cm ² And a curable resin layer having a thickness of 3 μm was cured and formed on a plastic substrate to obtain a printing sheet.

[Example 2]
Except having changed the compounding quantity of colloidal silica A from 12 mass parts to 25 mass parts, it carried out similarly to Example 1, and prepared the composition for curable resin layer formation of the composition shown in Table 1.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Example 3]
A curable resin layer-forming composition having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that colloidal silica B was used instead of colloidal silica A.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Example 4]
A curable resin layer-forming composition having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that colloidal silica C was used instead of colloidal silica A.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Example 5]
A printing sheet was obtained in the same manner as in Example 1 except that the curable resin layer forming composition was coated on a plastic substrate so that the thickness of the curable resin layer was 8 μm.

[Example 6]
Example 1 except that a mixture of 70 parts by mass of acrylate monomer (trade name Aronix M-215, manufactured by Toagosei Co., Ltd., molecular weight: 369, solid content: 100% by mass) and 30 parts by mass of methyl ethyl ketone was used instead of the urethane acrylate oligomer. In the same manner as above, a curable resin layer forming composition having the composition shown in Table 1 was prepared.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Comparative Example 1]
A curable resin layer forming composition having the composition shown in Table 2 was prepared in the same manner as in Example 1 except that colloidal silica A was not used.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Comparative Example 2]
A curable resin layer forming composition having the composition shown in Table 2 was prepared in the same manner as in Example 1 except that colloidal silica D was used instead of colloidal silica A.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Comparative Example 3]
Composition for forming a curable resin layer having the composition shown in Table 2 in the same manner as in Example 1 except that colloidal silica E was used instead of colloidal silica A and the blending amount was changed from 12 parts by mass to 24 parts by mass. A product was prepared.
A printing sheet was obtained in the same manner as in Example 1 except that the obtained composition for forming a curable resin layer was used.

[Comparative Example 4]
A printing sheet was obtained in the same manner as in Example 1 except that the curable resin layer forming composition was coated on a plastic substrate so that the thickness of the curable resin layer was 0.07 μm.

[Comparative Example 5]
A printing sheet was obtained in the same manner as in Example 1 except that the curable resin layer forming composition was coated on a plastic substrate so that the thickness of the curable resin layer was 20 μm.

[Measurement and evaluation method]
Dispersibility was evaluated with respect to the curable resin layer forming composition obtained in each example. Moreover, Ra of the surface of a curable resin layer was measured with the method shown below with respect to the printing sheet obtained in each case, and blocking resistance, transparency, and adhesiveness of ink were evaluated. These results are shown in Tables 1 and 2.

<Measurement of Ra>
Ra of the surface of the curable resin layer side of the printing sheet, in accordance with ASME B46.12, using a scanning probe microscope (Nanoscope IV and Nanoscope IIIa manufactured by Veeco), using a Si single crystal probe as a probe, The measurement mode is set to the taping mode, and the measurement area is 10 μm × 10 μm, and the image is captured. After the obtained image is subjected to Flatten processing (0th order) and Planefit processing (XY) once as image processing for removing swell using the analysis software attached to the scanning probe microscope. The surface roughness was calculated.

<Evaluation of dispersibility>
The composition for forming a curable resin layer was placed in a sealed glass bottle and allowed to stand at room temperature (23 ° C.) for 1 day. About the composition for curable resin layer formation after 1 day passed, the sedimentation degree (dispersibility) of the pigment in the said composition was observed visually, and the dispersibility was evaluated on the following evaluation criteria.
A: The pigment has not settled.
B: The pigment has settled.

<Evaluation of blocking resistance>
Whether a sheet for printing is placed on the glass plate so that the surface of the glass plate (11.5 cm × 25 cm) having a smooth surface is in contact with the curable resin layer, and whether wetting has occurred after 5 seconds have passed. Was visually observed. Similarly, a printing sheet is placed on a glass plate, and a weight of 1 kg is placed on a plastic substrate of the printing sheet to apply a weight to the printing sheet, and whether or not wetting has occurred after 5 seconds. It observed visually and evaluated blocking resistance on the following evaluation criteria. When wetting occurs, it means that the printing sheet is stuck on the glass plate.
A: Wetting did not occur even when a weight of 1 kg was applied to the printing sheet.
B: Wetting did not occur just by placing the printing sheet on the glass plate, but wetting occurred when a weight of 1 kg was applied to the printing sheet.
C: Wetting occurred only by placing a printing sheet on a glass plate.

<Evaluation of transparency>
The haze value of the printing sheet was measured using NDH5000 manufactured by Nippon Denshoku based on JIS K 7136, and the transparency was evaluated according to the following evaluation criteria.
A: Haze value is 1.00% or less.
B: Haze value exceeds 1.00%.

<Evaluation of ink adhesion>
Ink A was prepared by mixing 100 parts by mass of ink (trade name MRX HF-919 black, Teikoku Ink Co., Ltd.) and 5 parts by mass of a curing agent (trade name 210 curing agent, Teikoku Ink Co., Ltd.).
Separately, 100 parts by mass of ink (trade name MRX HF-619 white, manufactured by Teikoku Ink) and 5 parts by mass of a curing agent (trade name 210 curing agent, manufactured by Teikoku Ink) were mixed to prepare ink B. did.

The surface of the curable resin layer of the printing sheet was screen-printed using ink A and ink B, respectively, and dried at 80 ° C. for 1 hour to form a printed layer having a thickness of 15 μm on the curable resin layer.
In accordance with JIS K 5600-5-6, a cross-cut adhesion test was performed as follows.
Cellophane tape (trade name CT28, manufactured by Nichiban Co., Ltd.) was peeled off after being brought into close contact with the printed layer as if pressed from above with a finger. Of 100 squares, 100/100 is the case where the printed layer is not peeled off at all squares, and 0/100 is the case where the printed layer is peeled off at all squares. The ink adhesion was evaluated according to the following evaluation criteria.
A: 96/100 to 100/100
B: 50/100 to 95/100
C: 0/100 to 49/100

<Evaluation of dent>
A lamination PET film (trade name Lumirror U48, manufactured by Toray Industries, Inc., 10 cm × 10 cm, thickness 50 μm) is placed on the surface of the curable resin layer of the printing sheet, and the printing sheet 100 cm ² is placed on the lamination PET film. A load was applied so as to be 50 kg per hit, the state of the surface of the PET film for lamination after the passage of one day was visually confirmed, and the dent was evaluated according to the following evaluation criteria.
A: No dent was confirmed in the PET film.
B: A dent was confirmed in the PET film.

As is clear from Tables 1 and 2, the curable resin layer forming composition prepared in each Example had good dispersibility of the pigment (hydrophobized inorganic fine particles).
Moreover, the printing sheet obtained in each Example was excellent in transparency.
Moreover, since the printing sheet obtained in each Example was excellent in the blocking resistance with respect to a glass plate, it was shown that it is excellent also in the blocking resistance at the time of printing using a lithographic printing plate. Furthermore, since the adhesiveness with ink was also good, it was shown that it has excellent printability.
Further, in the printing sheet obtained in each example, since no dent was confirmed in the laminated PET film in the evaluation of the dent, no defect such as a dent occurred during winding.

On the other hand, the printing sheet obtained in Comparative Example 1 in which no hydrophobic inorganic fine particles were used was inferior in blocking resistance.
The composition for forming a curable resin layer prepared in Comparative Example 2 using hydrophilic inorganic fine particles in place of the hydrophobic inorganic fine particles was inferior in dispersibility of the pigment (hydrophilic inorganic fine particles). Moreover, the obtained printing sheet was inferior in blocking resistance and transparency, and dents were generated.
Although the printing sheet obtained in Comparative Example 3 using the hydrophobic inorganic fine particles having a large average particle diameter has blocking resistance, it is inferior in transparency and has dents.
The printing sheet obtained in Comparative Example 4 in which the thickness of the curable resin layer was thin was inferior in blocking resistance to the glass plate. Also, the ink adhesion was poor.
The printing sheet obtained in Comparative Example 5 in which the thickness of the curable resin layer was thick was inferior in transparency. Also, the ink adhesion was poor.

DESCRIPTION OF SYMBOLS 10 Printing sheet 11 Plastic base material 12 Curable resin layer 12a Irregular surface 13 Easy adhesion layer 20 Decorating sheet 21 Printing layer 30 Adhesive decorating sheet 31 Adhesive layer 32 Release sheet 33 Easy adhesion layer

Claims (4)

A printing sheet for a lithographic printing plate comprising a plastic substrate and a curable resin layer laminated on at least one surface of the plastic substrate,
The curable resin layer contains a curable resin and a pigment, and the pigment has an average particle diameter of 5 to 90 nm, and the surface is an inorganic fine particle subjected to a hydrophobic treatment,
The said sheet | seat for printing whose film thickness of the said curable resin layer is 0.1-15 micrometers.   The printing sheet according to claim 1, wherein the arithmetic average roughness (Ra) of the surface of the curable resin layer measured in accordance with ASME B46.12 is 0.5 to 15 nm.   A decorative sheet in which a printing layer is laminated on the curable resin layer of the printing sheet according to claim 1.   The adhesive decorating sheet by which the adhesion layer is laminated | stacked on the at least one surface of the decorating sheet of Claim 3.

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