JPH05138827A - Printing sheet - Google Patents

Abstract

PURPOSE:To provide a printing sheet with good offset printing ink absorption, ink-transfer, and vividness. CONSTITUTION:The sheet is of the type wherein an acceptor layer is provided on at least one surface of a carrier, and the acceptor is a layer that comprises a composite consisting mainly of water dispersion polymer, and particulate- aggregation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing sheet, and more particularly to a printing sheet suitable as a printing substrate such as offset printing or an inkjet recording substrate.

[0002]

2. Description of the Related Art When a fibrous support such as paper or cloth is directly printed, the ink absorbability is high, but the surface of the fibrous support is rough. Clear printing cannot be obtained due to bleeding. On the other hand, when a substrate such as plastic film lacks absorbability and oil absorption by itself, when used as a base material for offset printing or ink jet recording, the drying and curing of the ink is extremely slow, so printing on plastic film or the like. Was hard to do.

Therefore, in order to improve the flatness of the support and to absorb ink or the like, a coating material such as an acrylic emulsion is applied or impregnated (for example, JP-A 1-257042), talc, calcium carbonate. , A sheet for printing in which a layer containing a large amount of coarse particles of an inorganic powder such as kaolin or clay and organic powders such as plastic pigment is laminated and made porous by the voids between the particles (for example, JP-A-62-264947). Gazette) is known.

[0004]

However, in the case of the above-mentioned printing sheet, although the surface smoothness is improved in the case of, the inorganic porous layer has poor ink absorbability and has a drawback such as poor settability. In the case of, the pores are connected because they are made porous by the voids between the particles, and the ink flows laterally due to the non-uniform pore size, causing so-called bleeding or absorption. It has the disadvantage of unevenness in sex. Also, since a large amount of coarse inorganic particles are filled, the surface is inferior in smoothness, and pinhole-like voids are likely to occur at the time of ink transfer. Had drawbacks such as.

[0005]

The present invention is a sheet comprising a support and a receiving layer provided on at least one side thereof, the receiving layer comprising a water-dispersible polymer, a fine particle aggregate emulsion and / or a flat emulsion particle. A gist of the present invention is a printing sheet characterized by being a layer composed of a composition containing as a main component.

The support used in the present invention is paper,
Examples thereof include a fibrous support such as cloth, synthetic paper, and a plastic film. From the viewpoint of mechanical properties, water resistance, solvent resistance and the like, it is preferable to use a plastic film or synthetic paper, and a plastic film is particularly preferable.

As the plastic film used in the present invention, a publicly known plastic film can be appropriately used. Typical examples are polyester film, polycarbonate film, triacetyl cellulose film, cellophane film, polyamide film, polyimide film, polyphenylene sulfide film, polyetherimide film, polyether sulfone film, aromatic polyamide film, polysulfone film, polyolefin film. And so on. But,
From the viewpoint of mechanical properties, thermal properties, cost, etc., it is preferable to use a polyester film, a polycarbonate film, or a polyphenylene sulfide film, and among them, the polyester film is particularly preferable.

Polyester film is a general term for polymer films having an ester bond as the main chain of the main chain, and particularly preferred polyesters are polyethylene terephthalate, polyethylene 2,6-naphthalate, polyethylene α, β-bis (2 -Chlorphenoxy) ethane 4,4
'-Dicarboxylate, polybutylene terephthalate, etc. Of these, polyethylene terephthalate is most preferable in view of quality, economy and the like. Therefore, hereinafter, the description will proceed with polyethylene terephthalate as a representative of polyester.

In the present invention, polyethylene terephthalate (hereinafter abbreviated as PET) means that 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more has ethylene terephthalate as a repeating unit. Within this limited range, part of the acid component and / or glycol component may be replaced with 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, hexa Hydroisophthalic 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-cyclohexanedimethanol, 2,2-bis (4-hydroxyethoxyphenyl) sulfone, diethylene glycol, triethylene glycol, pentaerythritol,
Trimethylolpropane, polyethylene glycol, etc.

Known additives such as heat resistance stabilizer, oxidation resistance stabilizer, weather resistance stabilizer, UV absorber, organic slippery agent, pigment, dye, organic or inorganic fine particles, and filler are contained in this PET. You may mix | blend an agent, an antistatic agent, a nucleating agent, etc. The intrinsic viscosity of PET as described above (measured in orthochlorophenol at 25 ° C) is 0.40 to 1.2.
Those in the range of 0, preferably 0.50 to 0.80, and more preferably 0.55 to 0.75 dl / g are suitable for the present invention.

The PET film may be unoriented, uniaxially oriented or biaxially oriented, but a biaxially oriented PET film is preferred because of its excellent mechanical strength. Biaxial orientation P
The ET film is formed by stretching a PET sheet or film in a non-stretched state by a factor of 2.5 to 5 in each of so-called biaxial directions in the longitudinal direction and the width direction, and a biaxially oriented pattern by wide-angle X-ray diffraction. Refers to.

When the PET film has been subjected to a surface treatment by a known method, that is, a corona discharge treatment (in air, nitrogen, carbon dioxide, etc.) or an easy-adhesion treatment, the adhesion to the receiving layer, Water resistance and solvent resistance are improved, so that it can be more preferably used. For the easy-adhesion treatment, various known methods can be used. In the film manufacturing process, various easy-adhesives such as acrylic, urethane, and polyester are applied, or the above-mentioned film is uniaxially or biaxially stretched. Those coated with various types of easy-adhesives such as can be suitably used.

The base film may be either a transparent film or a colored film, but as the base film for printing, one having an whiteness of 80% or more by adding inorganic particles such as TiO ₂ and CaCO ₃ is particularly preferable. It is preferable from the standpoint of beauty after printing. Further, in the present invention, whiteness proposed in JP-A-2-29438, JP-A-2-29439 and the like,
It is preferable to apply a film support having both cushioning properties and low density.

The thickness of the film is not particularly limited, but is usually 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less, more preferably 30 μm or more 25.
It is preferably 0 μm or less. The center line average roughness of this film is 0.001 to 0.3 μm, preferably 0.005 to 0.2 μm, and more preferably 0.01 to 0.3 μm.
It is preferably 0.1 μm.

The receptive layer in the present invention is a layer composed of a composition containing a water-dispersible polymer and fine particle aggregate emulsion and / or flat emulsion particles as main components. The layer as a main component in the present invention means that the layer itself is 50% by weight or more, preferably 60% by weight in the receiving layer.
The above is indicated, and other substances may be added as appropriate.

The water-dispersible polymer referred to in the present invention is used for the purpose of improving the surface smoothness of the receiving layer and the adhesion to the support and ink. As the water-dispersible polymer, water dispersions of various polymers can be used. Specific examples include acrylic polymers, ester polymers, urethane polymers, olefin polymers, vinylidene chloride polymers, epoxy polymers, amide polymers. polymer,
And an aqueous dispersion of these modified products and copolymers can be used. From the viewpoint of mechanical stability of the coating film and coating strength, it is preferable to use an acrylic polymer or a urethane polymer, and an acrylic polymer is particularly preferable.

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

Acrylic polymers suitable as the polymer for forming the receiving layer of the present invention are at least 40 mol% or more of acrylic monomers and / or methacrylic monomers and their ester-forming monomers, acrylic monomers having various functional groups such as acrylic acid. , Methacrylic acid, alkyl acrylate, alkyl methacrylate (as the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl Groups, cyclohexyl groups, phenyl groups, benzyl groups, etc.), and hydroxy-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, Amide group-containing monomers such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-dimethylolacrylamide, N-methoxymethylmethacrylamide, and N-phenylacrylamide ,
It is composed of epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, salts of acrylic acid and methacrylic acid (sodium salt, potassium salt, ammonium salt, etc.), and these can be used together with various monomers. Examples of various monomers include
Epoxy group-containing monomers such as allyl glycidyl ether, monomers containing sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, etc.) or salts thereof, crotonic acid, itaconic acid , Maleic acid, fumaric acid,
And a monomer containing a carboxyl group or a salt thereof such as salts thereof, a monomer containing an acid anhydride such as maleic anhydride, itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl Examples thereof include trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinyl chloride, vinyl acetate and vinylidene chloride. The above-mentioned monomers are copolymerized using one kind or two or more kinds. The fine particle aggregate emulsion particles used in the present invention include a copolymer of a vinyl monomer copolymerizable with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid, and a vinyl monomer having a different composition. It is a fine particle aggregate emulsion particle in which heterogeneous polymers obtained by polymerizing the above are mixed.

Examples of vinyl monomers copolymerizable with the unsaturated carboxylic acid having the polymer composition of the copolymer include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. Butyl acid, vinyl acetate, acrylonitrile, (meth) acrylamide, N-methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate and the like are used.

Vinyl monomers having different polymer compositions different from the copolymer include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, vinyl acetate, acrylonitrile and butadiene. Etc. are used.

The particle size of the fine particle aggregate is an aggregate of fine particles in which the particle size of the aggregate particles is 0.2 to 3.0 μ and the particle size of the heterogeneous polymer in the particles is 0.05 to 0.5 μ. When the particle size of the heterogeneous polymer is less than 0.05 μ, the porosity is not sufficient and the absorption speed of ink is slow. On the other hand, if it exceeds 0.5 μm, an aggregate of fine particles cannot be obtained stably.

The flat emulsion particles used in the present invention are flat vinyl polymer emulsion particles.
At least one of the flat surfaces has a recess, the flat surface has a diameter D of 0.1 to 5.0 μ, and a ratio (D / d) to the thickness d of the particles is in the range of 1.5 to 5.0. Emulsion particles having such a structure are vinyl monomers such as styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, vinyl acetate, acrylonitrile, vinyl chloride, 2- Emulsion polymerization of hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, etc. is used to produce a polymer emulsion. Then, this emulsion is used as seed particles and a vinyl polymer of the same or different composition as the vinyl monomer It is obtained by emulsion polymerization with addition of a water-soluble organic solvent.

The diameter D of the flat surface of the flat particles is 0.1 to
5.0 μ, and the ratio (D / d) to the particle thickness d is 1.
It is in the range of 5 to 5.0. If the particle size is less than 0.1 μ, the porosity is insufficient and the absorption speed of ink is slow. Also,
If it exceeds 5.0 μ, the stability of the particles decreases.

These fine particle aggregate emulsion particles and flat emulsion particles can be used alone or in combination. The content of these emulsion particles in the coating film for the receiving layer is preferably 15 to 70 parts by weight, more preferably 20 to 50 parts by weight. If the content is less than 15 parts by weight, the porosity forming property is insufficient and the absorption rate of ink or the like tends to be slow. If it is contained in an amount of more than 70 parts by weight, the porosity-forming property is reduced and the pore size is reduced, the absorption rate of ink and the like is reduced, and the strength of the coating film is also inferior.

In the present invention, it is more effective to jointly use a colloidal silica having a beaded shape and / or a branched shape in order to increase the ink absorbability. Colloidal silica in the form of beads connected and / or branched is a non-precipitating particle that can be dispersed in a colloidal solution, forming pores,
The following silicas are preferable in terms of increasing ink absorbency. For example, those having a long chain structure in which spherical colloidal silica is connected in a beaded shape (a shape in which a plurality of spherical colloidal silica are connected in a chain), and those in which the connected silica is branched and / or bent can give. The colloidal silica is obtained by binding primary particles of spherical silica with a metal ion having a valence of 2 or more interposed between the particles to bond them, and at least 3 or more, preferably 5 or more, and more preferably 7 or more are connected. Further, it also includes particles in which particles connected in a beaded 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, etc., or may be one in which these particles are intervened and linked. The intervening metal ion is preferably a divalent or higher valent metal ion, and examples thereof include Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Al ²⁺ and Ti ²⁺ . In particular, when Ca ²⁺ is used, it is suitable for producing colloidal silica that is connected and branched in a beaded shape. The primary particle diameter of colloidal silica is 5 nm to 100 n.
m, preferably 7 nm to 50 nm, more preferably 8
When it is from 30 nm to 30 nm, it is preferable in terms of increasing the hole forming property. Further, the larger the number of primary particles of linked silica is, the more preferable. However, it is usually 3 or more and less than 100, preferably 5 or more and less than 50, and more preferably 7 or more and less than 30.

The content of the bead-like connected and / or branched silica particles in the coating film for the receiving layer is less than 80 parts by weight, preferably less than 70 parts by weight, more preferably less than 60 parts by weight. When the content is more than 80 parts by weight, the porosity forming property is reduced and the pore size is reduced, the absorption rate of ink and the like is reduced, and the strength of the coating film is also poor, so that it is difficult to cut. Defects such as dust are easily generated.

Known additives such as plasticizers, lubricants, surfactants, antistatic agents, cross-linking agents, cross-linking catalysts, heat-resisting agents and weather-resisting agents are added to the receiving layer of the present invention within a range that does not impair the effects of the present invention. Etc. may be added. In particular, the addition of an antistatic agent is preferable in terms of preventing double feeding in the case of sheet-fed printing, etc., and the addition of a crosslinking agent or a crosslinking catalyst provides coating layer toughness of the porous layer, water resistance,
It is more preferable because the chemical resistance and heat resistance are improved.

The composition constituting the receiving layer is obtained by mixing the water-dispersible polymer and the specific emulsion particles. Further, it can be obtained by using together and mixing colloidal silica in the form of beads connected and / or branched. In addition, specific emulsion particles and colloidal silica having a bead-like shape connected and / or branched are used as a reaction product with a water-dispersible polymer by emulsion polymerization or suspension polymerization in an aqueous medium when forming a water-dispersible polymer. Can also be used.

Although the thickness of the receiving layer is not particularly limited, it is usually 0.
1 to 50 μm, preferably 1 to 30 μm, and more preferably 3 to 20 μm. If the thickness is too thin, the ability to absorb ink or the like will be insufficient, and if it is too thick, the strength of the coating film will tend to be insufficient.

The printing sheet thus obtained has an extremely excellent absorption rate of ink and the like, good ink transferability and sharpness and excellent coating film strength, and is suitable as a substrate for offset printing, ink jet and the like. It can be used.

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

When the support is a plastic film, for example, PET, PET resin is melt extruded from a die by an extruder, cast into a sheet, and optionally stretched by a known method. The stretching method is not particularly limited, but for example, simultaneous biaxial vertical-horizontal, vertical-horizontal-vertical, horizontal-vertical, 2-step vertical → horizontal, 2-step vertical → horizontal → vertical, 2-step vertical → horizontal → It is desirable to be biaxially stretched by simultaneous biaxial stretching.

Next, a receiving layer made of the above-mentioned composition is provided on at least one surface of the support. As a method for providing the receiving layer, when the substrate is a PET film, a film support which is a substrate is pre-stretched in a film forming step, 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 base film single film.

And the like can be preferably applied. The coating method is not particularly limited and may be an extrusion laminating method, a melt coating method or the like, but a gravure coating method, a reverse coating method, a kiss coating method, a die coating method, because it is possible to coat a thin film at a high speed. A known method such as a metalling bar coating method can be applied. If necessary, a well-known surface treatment such as corona discharge treatment in air or other various atmospheres may be performed before coating to improve coatability, and more firmly form the receiving layer on the support. .. The concentration of the coating material and the conditions for drying the coating film are not particularly limited, but it is desirable that the conditions for drying the coating film be such that they do not adversely affect the properties of the receiving layer and the support.

[0038]

EXAMPLES The characteristic values of the present invention are based on the following measuring methods and evaluation criteria.

(1) Absorption rate Using a printing suitability tester RI-2 type (manufactured by Akira MFG. Co., Ltd.), TK Mark Five Beni (manufactured by Toyo Ink Co., Ltd.), which is an ink for offset printing, is printed, It was judged according to the following evaluation levels. The amount of ink applied was about 4 μm, and the absorptivity was evaluated on the printed surface with OK coated paper (Oji Paper Co., Ltd.).
A metal roll having a wire thickness of 353 g / cm was run from the top on which the coated surfaces were overlapped, and the time until the ink was not transferred to the OK coated paper was visually determined. ◎ Good (no transfer within 5 minutes) ○ Good (no transfer within 10 minutes) △ Slightly inferior (no transfer within 30 minutes) × Poor (transfer even after 30 minutes)

(2) Sharpness and bleeding of transfer surface The surface of the printing surface transferred by the above method was visually observed, and the presence or absence of transfer bleeding (a portion where ink is not transferred) was judged according to the following criteria. In addition, regarding the ink bleeding, the boundary between the printed portion and the non-printed portion was observed with a 100 × optical microscope, and the presence or absence of bleeding at the boundary surface was determined according to the following criteria. ◎ No transfer bleeding or bleeding is observed. ○ There is no transcribing, but slight blurring is observed. Δ There are 1 to 5 transfer blemishes / 10 cm ² that can be visually determined, and the boundary line is not clear. × There are countless spot-like transfer marks and large bleeding.

(3) Coating strength The surface of the receiving layer was cross-cut with 1 mm square and a 90 ° peel test was performed using a cellophane adhesive tape manufactured by Nichiban Co., Ltd. to determine the residual rate of the receiving layer. ◎ Remaining rate 100% ○ Remaining rate 80% or more △ Remaining rate 50% or more × Remaining rate less than 50%

The present invention will be described with reference to the following examples and comparative examples, but the invention is not limited thereto.

Example 1 As a support, the following coating agent was applied to one side of a biaxially stretched PET film having a thickness of 100 μm so that the thickness after drying was 10 μm, and dried at 130 ° C. for 2 minutes to obtain a printing sheet. It was In addition, the coated surface of the PET film was used after being subjected to corona discharge treatment in air.

[Coating Composition] Acrylic polymer emulsion (methyl methacrylate / average particle diameter 0.2 μm)
50 parts by weight (solid content weight ratio) of ethyl acrylate / acrylic acid (60/35/5% by weight) copolymer and fine particle aggregate emulsion particles (for example, Mitsuru 110C manufactured by Mitsui Toatsu Chemicals, Inc., average particle) 50 parts by weight (diameter 1.0 μ) was diluted with water to give a 30% by weight coating agent. The characteristics of this printing sheet are shown in Table 1. As is clear from Table 1, the absorption speed of ink and the like was high, and excellent characteristics such as sharpness and bleeding were exhibited.

Example 2 The same procedure as in Example 1 was repeated except that the emulsion particles were changed to flat emulsion particles (for example, Mitsui Toatsu Chemical Co., Ltd. Muticle 240D, average particle size 0.5 μ). A printing sheet was obtained. As shown in Table 1, the ink has excellent properties such as ink absorbency, printing clarity, and coating strength.

Example 3 In the coating material of Example 1, 25 parts by weight of the emulsion particles were used as fine particle aggregate emulsion particles (for example, Mitsui Toatsu Chemical Co., Ltd., Muticle 110C, average particle size 1.0 μ) and flattened. Emulsion particles (for example, Mitsui Toatsu Chemical Co., Ltd. Muticle 240D, average particle size 0.5)
μ) was changed to 25 parts by weight to obtain a printing sheet by the same method. As shown in Table 1, the ink has excellent properties such as ink absorbency, printing clarity, and coating strength.

Comparative Example 1 A printing sheet was prepared in the same manner as in the coating material of Example 1, except that spherical emulsion particles having an average particle diameter of 0.6 μm were used in place of the fine particle aggregated emulsion particles. As shown in Table 1, the ink has a defect that the absorption speed of the ink and the like is poor, and the sharpness and bleeding are poor.

[0048]

[Table 1]

Example 4 A printing sheet was obtained by applying the following coating agent to one side of a support similar to that in Example 1 by the same method.

[Coating Composition] Acrylic polymer emulsion (methyl methacrylate / average particle diameter 0.2 μm)
40 parts by weight (solid content weight ratio) of ethyl acrylate / acrylic acid (60/35/5 wt% copolymer) and fine particle aggregate emulsion particles (for example, Mitsui 110C manufactured by Mitsui Toatsu Chemicals, Inc., average particle) Diameter 1.0 μ) 30 parts by weight and branched beaded colloidal silica (for example, Snowtex UP manufactured by Nissan Kagaku KK, average particle diameter 0.015 μ)
m) 30 parts by weight (solid content weight ratio) was diluted with water to obtain a 30% by weight coating agent.

The characteristics of this printing sheet are shown in Table 2.
As is clear from Table 2, the absorption speed of ink etc. is high,
It exhibited excellent characteristics in both sharpness and bleeding.

Examples 5 and 6 Other than changing the composition ratio of the composition in the coating material of Example 4,
A printing sheet was obtained by the same method. As shown in Table 2, it has excellent properties in ink absorbency, sharpness and coating strength.

[0053]

[Table 2]

[0054]

INDUSTRIAL APPLICABILITY The present invention has the following excellent properties by laminating a water-dispersible polymer and a receiving layer using a fine particle aggregate emulsion and / or flat emulsion particles on the surface of a support. is there.

(1) The workability is excellent because the absorption speed of ink or the like in offset printing is extremely fast and the set time in sheet-fed printing is short. (2) Small ink bleeding and good sharpness. (3) Excellent coating strength.

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Claims (3)

[Claims] 1. A sheet comprising a support and a receptive layer provided on at least one side thereof, the receptive layer comprising a water-dispersible polymer and fine particle aggregate emulsion and / or flat emulsion particles as main components. A printing sheet, which is a layer composed of 2. The printing sheet according to claim 1, wherein the receiving layer contains colloidal silica having a beaded and / or branched bead shape. 3. The printing sheet according to claim 1, wherein the support is a plastic sheet.