JP3120449B2 - Sheets for recording media for printing - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a recording medium sheet for printing, and more particularly, to a printing substrate suitable for a printing substrate such as offset printing and an inkjet recording substrate. It is about a sheet.

[Prior art] When printing is directly performed on a fibrous support such as paper or cloth, the ink absorbs quickly, but the surface of the fibrous support is rough, so that printing omissions or ink flow in the horizontal direction may occur. Clear printing cannot be obtained due to so-called bleeding. on the other hand,
When used as a substrate for offset printing or ink jet recording, the support such as a plastic film itself has insufficient absorption and oil absorption properties, so the drying and curing of the ink is extremely slow, so printing on a plastic film is difficult. .

Therefore, to improve the flatness of the support, to apply a coating agent such as acrylic resin to absorb the ink and the like,
Or impregnated or (for example, JP-A 1-257042), a layer containing a large amount of coarse particles of organic powders such as inorganic fillers such as talc, calcium carbonate, kaolin, clay and plastic pigments, A printing recording medium sheet made porous by voids between particles is known (for example, JP-A-62-264947).

[Problems to be Solved by the Invention] However, in the above-described recording medium sheet for printing,
In the case of, although the smoothness of the surface is improved, the non-porous layer has disadvantages such as poor ink absorption and poor settability. And the holes are connected to each other, and the holes have a non-uniform diameter, so that the ink flows in the horizontal direction, so that there is a drawback that so-called bleeding occurs and uneven absorption occurs. In addition, the surface is inferior in smoothness due to a large amount of coarse inorganic particles being filled, and pinhole-shaped peeling is likely to occur at the time of ink transfer. And the like.

The present invention improves such disadvantages, and is extremely excellent in the absorbability of the ink and the solvent in the ink for improving the drying speed of the printing surface, and has a smooth surface and excellent transferability and sharpness of the ink. It is an object of the present invention to provide a recording medium sheet for printing excellent in coating film strength without bleeding.

[Means for Solving the Problems] The present invention is a sheet provided with a receiving layer on at least one surface of a support, wherein the receiving layer is a water-dispersible polymer (A)
And a layer mainly composed of colloidal silica (B) having a bead-like connected and / or branched shape and substantially spherical organic and / or inorganic particles (C). The characteristic feature is a recording medium sheet for printing.

The support used in the present invention is not particularly limited,
Examples thereof include fibrous supports such as paper and cloth, synthetic paper, and plastic films. It is preferable to use a plastic film or synthetic paper from the viewpoints of mechanical properties, water resistance, solvent resistance and the like, and a plastic film is particularly preferable.

As the plastic film used in the present invention, a known plastic film can be used. Typical ones are polyester film, polycarbonate film,
Triacetyl cellulose film, cellophane film,
Examples thereof include a polyamide film, a polyimide film, a polyphenylene sulfide film, a polyether imide film, a polyether sulfone film, an aromatic polyamide film, a polysulfone film, and a polyolefin film. But the mechanical properties,
It is preferable to use a polyester film, a polycarbonate film, or a polyphenylene sulfide film from the viewpoints of thermal characteristics, cost, and the like, and a polyester film is particularly preferable.

Polyester film is a general term for a polymer film having an ester bond as a main bonding chain. Particularly preferred polyesters are polyethylene terephthalate, polyethylene 2,6-naphthalate, and polyethylene α, β-bis (2-chlorophenoxy). ) Ethane 4,4'-
Examples thereof include dicarboxylate and polybutylene terephthalate, and among these, polyethylene terephthalate is most preferable in consideration of quality, economy, and the like. Therefore, description will be made hereinafter with polyethylene terephthalate as a representative of polyester.

In the present invention, polyethylene terephthalate (hereinafter referred to as PET)
The term "abbreviated as") means that 80 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more has ethylene terephthalate as a repeating unit, but within this limited range, an acid component and / or a glycol component. May be replaced by a third component as described below.

-Acid component- Isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-
Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, p-β-hydroxyethoxybenzoic acid,
Adipic acid, azelaic acid, sebacic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, ε-oxycaproic acid, trimellitic acid, trimesic acid, pyromellitic acid, α, β-bis (2-chlorophenoxy) ethane
4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, etc.-glycol component-propylene glycol, butylene glycol, hexabutylene glycol, decamethylene glycol, neopentyl glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexane Dimethanol, 2,2-bis (4
-Hydroxyethoxyphenyl) sulfone, diethylene glycol, triethylene glycol, pentaerythritol, trimethylolpropane, polyethylene glycol and the like.

In addition, known additives in this PET, for example, heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, charging You may mix an inhibitor, a nucleating agent, etc. The intrinsic viscosity of PET as described above (measured in orthochlorophenol at 25 ° C) is between 0.40 and 1.20, preferably between 0.50 and 0.80,
More preferably, those in the range of 0.55 to 0.75 dl / g are suitable for the content of the present invention.

The PET film can be used in any of unoriented, uniaxial or biaxial orientation, but biaxially oriented PET film is preferable because of its excellent mechanical strength. The biaxially oriented PET film is made by stretching a non-stretched PET sheet or film about 2.5 to 5 times each in the so-called biaxial directions of the longitudinal direction and the width direction. Indicates a pattern.

If the PET film is a film that has been subjected to a surface treatment by a known method, that is, a corona discharge treatment (in air, in nitrogen, in carbon dioxide gas, etc.) or an easy-adhesion treatment, adhesion to the receptor layer, water resistance, Since the solvent resistance and the like are improved, it can be more preferably used. Various methods known in the art can be used for the easy adhesion treatment.Acrylic-based, urethane-based, and polyester-based various easy-adhesives are applied in the film manufacturing process, or the film after uniaxial or biaxial stretching is applied to the film. Those coated with various types of easy-to-adhesive agents such as described above can be suitably used.

The base film may be a transparent film or a colored film, but TiO ₂ , CaC
It is preferable that the whiteness is 80% or more by adding inorganic particles such as O _{3 in view} of beautifulness after printing. Further, in the present invention, it is preferable to use a film support provided with whiteness, cushioning property, low density and the like proposed in JP-A-2-29438 and JP-A-2-29439.

The thickness of this film is not particularly limited, but is usually 1 μm.
Not less than 500 μm, preferably not less than 10 μm and not more than 300 μm,
More preferably, the thickness is 30 μm or more and 250 μm or less. The center line average roughness of this film is 0.001 ~
0.3 μm, preferably 0.005 to 0.2 μm, more preferably
Desirably, it is 0.01 to 0.1 μm.

The receiving layer in the present invention is a layer provided on a support, and in a recording medium for printing, a printing ink or the like is formed thereon. Therefore, the printing ink adhesion, absorption,
It is required to have excellent drying properties.

The receiving layer in the present invention is a layer composed of a composition containing a water-dispersible polymer, a specific colloidal silica, and inorganic and / or organic particles as main components. The layer as the main component in the present invention refers to a layer which is 50% by weight or more, preferably 60% by weight or more in the receiving layer, and other substances may be appropriately added.

The water-dispersible polymer (A) used in the present invention is used for improving the surface smoothness of the receptor layer and the adhesion to the support and the ink. As the water-dispersible polymer, aqueous dispersions of various polymers can be used. Specific examples include an acrylic polymer, an ester polymer, a urethane polymer, an olefin polymer, a vinylidene chloride polymer, an epoxy polymer, and an amide polymer. Aqueous dispersions such as polymers and their modified products and copolymers can be used. The use of an acrylic polymer or a urethane polymer is preferred in terms of the mechanical stability of the coating film and the strength of the coating film, and an acrylic polymer is particularly preferable.

The polymer used in the present invention is preferably dispersed in water and has a particle shape. When the particles do not have a particle shape, that is, a polymer dissolved in a water-soluble polymer, an organic solvent, or the like, it is difficult to make the particles porous. The particles are preferably dispersed in primary particles, but need not necessarily be dispersed in primary particles, and may include secondary aggregated particles.

The acrylic polymer suitable as the receptor layer forming polymer of the present invention is at least 40 mol% or more of an acrylic monomer and / or a methacrylic monomer and their ester-forming monomers, acrylic monomers having various functional groups such as acrylic acid and methacrylic acid. , Alkyl acrylate, alkyl methacrylate (the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group,
Ethylhexyl, lauryl, stearyl, cyclohexyl, phenyl, benzyl, etc.), and 2
Hydroxy-containing monomers such as -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N Amide group-containing monomers such as methylol methacrylamide, N-dimethylol acrylamide, N-methoxymethyl methacrylamide and N-phenylacrylamide; epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; acrylic acid; salts of methacrylic acid (sodium Salt, potassium salt, ammonium salt, etc.)
And these can be used in combination with various monomers. Examples of various monomers include epoxy group-containing monomers such as allyl glycidyl ether,
Styrenesulfonic acid, vinylsulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, etc.)
Such as a monomer containing a sulfonic acid group or a salt thereof,
Monomers containing a carboxyl group or a salt thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid, and salts thereof, monomers containing an acid anhydride such as maleic anhydride and itaconic anhydride, vinyl isocyanate, allyl isocyanate , Styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleate monoester, alkyl fumarate monoester, acrylonitrile, methacrylonitrile, alkyl itaconate monoester, vinyl chloride, vinyl acetate, vinylidene chloride, etc. can give.
The above-mentioned monomers are copolymerized using one kind or two or more kinds.

Colloidal silica (B) having a bead-like connected and / or branched shape used in the present invention is a non-precipitating particle that can be dispersed in a colloid solution and forms pores to improve ink absorbency. Such silica is preferred.
For example, spherical colloidal silica is connected in a bead shape (a shape in which a plurality of spherical colloidal silicas are connected in a chain).
And those having linked and branched and / or bent silica.

The above-mentioned colloidal silica is obtained by linking primary particles of spherical silica with particles of two or more valent metal ions and connecting the particles, and at least three, preferably five or more, and more preferably seven or more are connected. And further includes those in which beads connected in a bead shape are branched and / or bent. Further, it may be a composite or mixed particle of colloidal silica and other inorganic particles, for example, alumina, ceria, titania, or the like, or may be a particle in which these are interposed and connected. The metal ion to be interposed is preferably a divalent or higher valent metal ion, for example, Ca ²⁺ , Mg
²⁺ , Ba ²⁺ , Al ²⁺ , Ti ²⁺ and the like. In particular, when Ca ²⁺ is used, it is suitable for producing colloidal silica linked and branched in a bead shape. When the primary particle size of the colloidal silica is from 5 nm to 100 nm, preferably from 7 nm to 50 nm, and more preferably from 8 nm to 30 nm, it is preferable in that the pore forming property is increased. Further, the number of primary particles of the linked silica is preferably as large as possible, but it is usually from 3 to less than 100, preferably from 5 to less than 50, more preferably from 7 to less than 30.

The content of the beads connected and / or branched in the coating of the receiving layer in the beads is preferably 3 to 80 parts by weight, more preferably 10 to 70 parts by weight, and still more preferably 20 to 60 parts by weight. When the content is less than 3 parts by weight, there is no porosity, and the absorption rate of ink or the like tends to be slow. When the content is more than 80 parts by weight, the porosity is reduced and the pore size is reduced, so that the absorption speed of ink and the like is reduced, and the strength of the coating film is poor, so that dust is generated at the time of cutting. It is easy to cause disadvantages such as easy operation.

The substantially spherical organic and / or inorganic particles (C) used in the present invention may be inorganic particles, organic particles, or mixtures thereof as long as the particles are individually spherical particles. It may be. Such particles are used for improving the ink absorbency, the running property of the support during printing, and the surface smoothness. Inorganic particles include spherical silica, alumina, calcium carbonate, magnesium carbonate, titanium oxide, zirconium oxide, calcium silicate, diatomaceous earth, kaolin, glass beads, silica sand, aluminum silicate, sericite, aluminum oxide, tin oxide, iron oxide And hydrophilic fine particles that do not dissolve in water, such as barium sulfate, barium carbonate, zinc oxide, and calcium hydroxide. In addition, as the organic particles, polymer fine particles such as an acrylic resin, a benzoguanamine resin, an epoxy resin, a urea formmarin resin, a melamine resin, and a polyamide resin can be used.

With the above-mentioned inorganic and / or organic particles, printing recording medium sheets having different smoothness depending on the particles used can be obtained.
For example, smoothness is 2 seconds or more in order to have an effect of fast ink absorption, excellent drying property, and enhancing print clarity.
Preferably, it is less than 1000 seconds. On the other hand, a smoothness of 1,000 seconds or more is preferred for the purpose of increasing the ink absorbency, increasing the surface smoothness and gloss, and improving the effects such as no ink bleeding. As the particles satisfying the former property, porous particles are preferable. The porous particles referred to in the present invention are porous having a spherical shape and pores on the particle surface, and a liquid inside as a hollow porous or non-hollow porous form,
Solid and gas can be freely enclosed and released. Typical production methods include, for example, `` Interfacial reaction method '' described in JP-A-62-292476 or JP-B-54-6251, JP-B-57-55454 and JP-B-55-43404. That is, the method of adjusting the powder by an aqueous solution precipitation reaction. In the adjustment process, a water-in-oil type (W /
By using an O type) emulsion, hollow, spherical, and porous fine particles can be prepared and manufactured.

Specific examples of the wall material of the material constituting the porous particles include, for example, alkaline earth metal carbonates such as calcium carbonate, magnesium carbonate and barium carbonate, and alkali alkali metals such as calcium silicate, magnesium silicate and barium silicate. Alkaline earth metal phosphates such as earth metal silicates, calcium phosphate, magnesium phosphate and barium phosphate, alkaline earth metal sulfates such as calcium sulfate, magnesium sulfate and barium sulfate, silicic anhydride, titanium oxide, Metal oxides such as manganese oxide, aluminum oxide, tin oxide, iron oxide, zinc oxide, antimony oxide, calcium hydroxide, aluminum hydroxide, nickel hydroxide,
Metal hydroxides such as chromium hydroxide, metal silicates such as zinc silicate, aluminum silicate and copper silicate, metal carbonates such as zinc carbonate, aluminum carbonate, cobalt carbonate and nickel carbonate, melamine, acrylic and styrene And resin particles such as styrene-divinylbenzene and nylon. Among them, in the present invention, those composed of silicic anhydride are preferable in terms of the properties of the recording medium sheet for printing.
Particularly preferred.

The average particle size of the porous particles is 0.5 to 25 μm, preferably 1.0
Those having a thickness of from 15 to 15 μm are preferred in terms of handleability, coatability, properties of a recording medium sheet for printing, and the like. Further, in the present invention, the specific surface area of the porous particles needs to be in the range of 150 to 500 m ² / g, preferably 180 to 450 m ² / g, more preferably 200 to 400 m ² / g. If it is smaller than the range of the present invention, it is not preferable because the ink absorbency is insufficient and the color material in the ink cannot be completely captured, which causes a problem such as deterioration of sharpness. If it is larger than the range of the present invention, it is not preferable because the ink absorbability is too good and the ink spreads and spreads, and an image having a high ink density causes inconvenience such as rubbing and smearing of the ink when touched by hand. In the case of hollow porous particles, it is desirable that the wall thickness is uniform because there is deformation and destruction due to external force.

Colloidal particles are preferred as the particles satisfying the latter property. Colloidal particles in the present invention,
Particles (dispersoids) that can be dispersed in the colloid solution, and the primary particles have a particle diameter of 1 to 500 mμ. The colloidal particles are substantially made of an inorganic material, for example, silica, alumina, lithium silicate, antimony oxide,
It is made of ferrite or the like. Specific examples include colloidal silica, alumina sol, lithium silicate sol, antimony sol, and ferrite sol. Colloidal silica is particularly preferred in terms of transparency, water resistance, weather resistance and the like. Colloidal silica is an ultrafine silica sol or ultrafine silica powder in which silicon dioxide is dispersed in water in a colloidal form, and both have a primary particle diameter of 7
It shows a spherical shape at 5050 mμ.

The content of the particles in the receiving layer is preferably from 10 to 70% by weight, more preferably from 20 to 50% by weight. Content is 10% by weight
If it is less than 70%, the ink absorbency becomes insufficient, and if it is 70% by weight or more, the adhesion between the receiving layer and the film support tends to decrease.

Known additives such as a plasticizer, a lubricant, a surfactant, an antistatic agent, a cross-linking agent, a cross-linking catalyst, a heat-resistant agent, a weathering agent and the like are added to the receiving layer of the present invention within a range that does not impair the effects of the present invention. May be. In particular, the addition of an antistatic agent is preferable from the viewpoint of preventing double feed in the case of sheet-fed printing, and the addition of a crosslinking agent or a crosslinking catalyst is effective in coating film toughness, water resistance, and chemical resistance of the porous layer.
It is more preferable because the heat resistance is improved.

The specific colloidal silica or other particles can be used as a reaction product with the water-dispersible polymer by emulsion polymerization or suspension polymerization in an aqueous medium when the water-dispersible polymer is produced.

The thickness of the receiving layer is not particularly limited, but is usually 0.1 to 50 μm,
It is preferably about 1 to 30 μm, and more preferably about 3 to 20 μm. If the thickness is too small, the absorption capacity of the ink or the like becomes insufficient, and if it is too thick, the strength of the coating film tends to be insufficient.

The sheet for a printing recording medium thus obtained has an extremely excellent absorption rate of ink and the like, and has good ink transferability, clearness, excellent coating strength, and is suitable as a base material for offset printing, inkjet, etc. It can be used.

Next, a method for producing a sheet for a printing recording medium of the present invention will be described. However, it is not limited to this.

When the support is a plastic film, for example, PET, the PET resin is melt-extruded from a die with an extruder, cast into a sheet, and if necessary, stretched by a known method. Although the stretching method is not particularly limited, for example, simultaneous biaxial vertical-horizontal, vertical-horizontal-vertical, horizontal-vertical, two-stage vertical →
It is desirable that the film is biaxially stretched by stretching such as horizontal, two-stage vertical → horizontal → vertical, two-stage vertical → horizontal → simultaneous biaxial stretching.

Next, a receiving layer comprising the above-described composition is provided on at least one surface of the support. As a method of providing the receiving layer, when the substrate is a PET film, a film support serving as a substrate is stretched in advance in a film forming process, then a solution adjusted to a predetermined amount is applied, and then dried. .

A method of providing a coating-drying step after winding as a single base film.

And the like can be preferably applied. The application method is not particularly limited, and an extrusion lamination method, a melt coating method, or the like may be used, but a gravure coating method, a reverse coating method, a kiss coating method, a die coating method, because a thin film can be coated at a high speed. A known method such as a metaling bar coating method can be applied. If necessary, a known surface treatment such as a corona discharge treatment in air or other various atmospheres may be performed before the coating, so that the coating property is improved and the receiving layer can be more firmly formed on the support. . The concentration of the coating agent and the conditions for drying the coating film are not particularly limited, but the drying conditions for the coating film are desirably performed within a range that does not adversely affect the properties of the receiving layer and the support.

[Evaluation Method] The characteristic values of the present invention are based on the following measurement methods and evaluation criteria.

(1) Absorption speed Using the printability tester RI-2 type (manufactured by Akira Seisakusho Co., Ltd.), printing of TK Mark Five Beni (manufactured by Toyo Ink Co., Ltd.), which is an ink for offset printing, was performed and evaluated as follows. The judgment was made based on the level. The amount of ink applied was about 4 μm, and the absorbability was evaluated by running a metal roll with a wire thickness of 353 g / cm from above with the coated surface of OK coated paper (manufactured by Oji Paper Co., Ltd.) superimposed on the printed surface. The time until the ink was no longer transferred to the coated paper was visually determined.

◎ Good (no transfer within 5 minutes) ○ Good (no transfer within 10 minutes) △ Slightly poor (no transfer within 30 minutes) × Bad (transfer even after 30 minutes or more) (2) Clearness of transfer surface, Bleeding The surface of the printing surface transferred by the above method was visually observed, and the presence or absence of a missing transfer (a portion where ink was not transferred) was determined according to the following criteria. In addition, the bleeding of the ink was determined by observing the boundary between the printed part and the non-printed part with an optical microscope of 100 parts and judging the presence or absence of bleeding at the boundary surface according to the following criteria.

 転 写 No transfer bleeding or bleeding was observed.

 ○ There is no transfer bleeding, but slight bleeding is observed.

Δ 1 to 5 transfer bleeds, which can be visually judged, are present in 10 cm ^2, and the boundaries are not clear.

× There are countless spots in the transfer, and bleeding is large.

(3) Coating Strength The surface of the receiving layer was subjected to a 1 mm square cross-cut, and a 90 ° peel test was performed using a cellophane adhesive tape manufactured by Nichiban Co., Ltd., to determine the residual ratio of the receiving layer.

◎ Residual rate 100% ○ Residual rate 80% or more △ Residual rate 50% or more × Residual rate less than 50% (4) Smoothness Oken type air permeability smoothness tester “Type KB15” (Asahi Seiko Co., Ltd.) And the smoothness was determined.

(5) Center line average roughness Measured at a cutoff of 0.25 mm in accordance with JIS B 0601-1976.

(6) Gloss In accordance with JIS Z 8741, the surface gloss at an incident angle of 60 ° was measured.

(7) Specific surface area (BET method) (For example, described in J. Am. Chem. Soc., 38 , 2219 (1916).) Nitrogen molecules are adsorbed on the particle surface, and the adsorbed amount is measured. The volume of the adsorbed gas when the entire surface was covered with the single-molecule adsorption layer was determined by the following equation (1), and this was divided by the volume of one nitrogen molecule to determine the number of molecules. The specific surface area was obtained by multiplying the number of molecules by the volume σ occupied by one adsorbed molecule of the following formula (2) on the surface.

V = VmCP / (Ps-P) [1+ (c-1) P / Ps] (1) where Vm is the volume of the adsorbed molecules when the entire surface is covered with the monomolecular adsorption layer, and V is the pressure P Volume of adsorbed gas,
P indicates pressure, Ps is a saturated vapor pressure, and C is a constant.

σ = 1.091 (M / Np) (2) where σ is the volume occupied by one adsorbed molecule on the surface, M is the molecular weight, N is the Avogadro number, and p is the density of the adsorbed molecular layer on the surface.

[Effects of the Invention] The present invention relates to a water-dispersible polymer,
Alternatively, by laminating a colloidal silica having a branched shape and a receiving layer using other particles on the surface of the support, the following excellent characteristics are exhibited.

(1) The workability is excellent because the absorption speed of ink and the like in offset printing and the like is extremely high and the set time in sheet-fed printing is short.

(2) Excellent sharpness due to excellent surface smoothness.

(3) Ink bleeding is small.

EXAMPLES The present invention will be described with reference to the following Examples and Comparative Examples.
It is not limited to these.

Example 1 The following coating agent was applied to one surface of a biaxially stretched PET film having a thickness of 100 μm as a support so that the thickness after drying became 10 μm, and dried at 130 ° C. for 2 minutes to obtain a sheet for a recording medium for printing. Was. The surface of the PET film that had been subjected to corona discharge treatment in air was used.

[Coating composition] 49 parts by weight (solid content weight ratio) of an acrylic polymer emulsion (methyl methacrylate / ethyl acrylate / acrylic acid (60/35/5% by weight) copolymer) having an average particle diameter of 0.2 μm and a branched bead Colloidal silica (for example, Nissan Chemical Co., Ltd. Snowtex UP, average particle size 0.015μ)
m) 30 parts by weight (solids weight ratio) and average particle diameter as particles
30 parts by weight of amorphous silica “Mizukasil” P-78A (manufactured by Mizusawa Chemical Industry Co., Ltd.) having a thickness of 3.5 μm and a specific surface area of 350 m ² / g was diluted with water to prepare a 30% by weight coating agent.

As is clear from Table 1, this print recording medium sheet has a high absorption rate of ink and the like, and has excellent characteristics in both sharpness and bleeding.

Comparative Example 1 A printing recording medium sheet was prepared in the same manner as in Example 1, except that spherical colloidal silica having an average particle diameter of 0.015 μm was used in place of the branched beaded colloidal silica in the coating composition of Example 1. As shown in Table 1, the ink absorption speed was high, but the printing clarity and the coating film strength were inferior.

Comparative Example 2 A printing recording medium sheet was obtained in the same manner as in Example 1, except that the particles were omitted. As shown in Table 1, the inks had disadvantages such as poor absorption speed of ink and the like, and inferior sharpness and bleeding.

Examples 2 to 4 Printed recording medium sheets were obtained by the same method as in Example 1 except that the amount of particles added (Example 2) and the particles (Examples 3 and 4) were changed. As shown in Table 1, the ink has excellent properties in ink absorbency, print definition, and coating film strength.

Example 5 Polyester short fiber having a fineness of 5 denier and a fiber length of 51 mm was passed through a conventional cotton-opening / carding process to obtain a laminated web.
Needle punch with a needle density of 100 needles / cm ² and average weight 50g
/ m ² of nonwoven fabric was obtained. Using a coating material having the same composition as in Example 1 for this support, a sheet for a recording medium for printing was obtained by the same method. As shown in Table 1, the properties of this sheet were all excellent.

Example 6 A sheet for a printing recording medium was obtained on one surface of the same support as in Example 1 using the following coating agent in the same manner.

[Coating composition] 30 parts by weight (solid content weight ratio) of an acrylic polymer emulsion (methyl methacrylate / ethyl acrylate / acrylic acid (60/35/5% by weight) copolymer) having an average particle size of 0.2 μm and a branched bead Colloidal silica (for example, Nissan Chemical Co., Ltd. Snowtex UP, average particle size 0.015μ)
m) 40 parts by weight (solid content weight ratio) and spherical colloidal silica (for example, Snowtex manufactured by Nissan Chemical Co., Ltd.)
20, an average particle size of 0.015 μm) and 30 parts by weight (solids weight ratio) were diluted with water to obtain a 30% by weight coating composition.

Table 2 shows the properties of the recording medium sheet for printing.
As is clear from Table 2, the absorption speed of ink and the like is high,
Surface smoothness and glossiness were high, and excellent characteristics were exhibited in both sharpness and bleeding.

Comparative Example 3 A recording medium sheet for printing was obtained in the same manner as in Example 6, except that the spherical colloidal silica was omitted. As shown in Table 2, the ink absorption speed is high, but the glossiness is low, the sharpness and bleeding are poor, and the coating film strength is poor.

Comparative Example 4 A printing recording medium sheet was obtained in the same manner as in Example 6, except that the branched beaded colloidal silica was omitted from the coating composition of Example 6. As shown in Table 2, the inks had disadvantages such as poor absorption speed of ink and the like, and inferior in sharpness and blur.

Examples 7 and 8 Printed recording medium sheets were obtained in the same manner as in Example 6, except that the composition ratio of the composition was changed.
As shown in Table 2, the surface smoothness and glossiness are high, and the ink has excellent characteristics of ink absorbency, sharpness, and coating film strength.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-219083 (JP, A) JP-A-2-274587 (JP, A) JP-A-61-3777 (JP, A) JP-A-61-2777 290085 (JP, A) JP-A-2-129992 (JP, A) JP-A-63-178074 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (6)

(57) [Claims] 1. A sheet having a receiving layer provided on at least one side of a support, wherein the receiving layer is a water-dispersible polymer (A).
And a layer mainly composed of colloidal silica (B) having a rosary-like shape connected and / or divided, and substantially spherical organic and / or inorganic particles (C). A sheet for a printing recording medium characterized by the above-mentioned. 2. The printing according to claim 1, wherein the substantially spherical organic and / or inorganic particles (C) are porous particles having a specific surface area of 150 to 500 m ² / g. Sheet for recording media. 3. The recording medium sheet for printing according to claim 2, wherein the smoothness of the receiving layer is in a range of 2 seconds or more and less than 1000 seconds. 4. The recording medium sheet for printing according to claim 1, wherein the substantially spherical organic and / or inorganic particles (C) are colloidal particles. 5. The sheet for a printing recording medium according to claim 4, wherein the smoothness of the receiving layer is 1000 seconds or more. 6. The printing recording medium sheet according to claim 1, wherein the support is a plastic sheet.