JP2001022111A - Transfer paper for electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain printed matter having no deterioration of luster of an image part and blank grossiness of an unprinted part by coating base paper with specified soap-free latex. SOLUTION: After a coating composition based on a pigment and an adhesive is applied on at least one side of the base paper of transfer paper for electrophotography, the soap-free latex is applied on at least one side of the base paper to which luster is imparted. The soap-free latex is obtained by copolymerizing an unsaturated monomer mixture consisting of an ethylenically unsaturated carboxylic acid ester monomer and an ethylenically unsaturated monomer to be copolymerizable with this monomer in the presence of a partially or completely neutralized substance of an alkali-soluble polymer consisting of two or more ethylenically unsaturated carboxylic acid ester monomers, an ethylenically unsaturated acid monomer and an ethylenically unsaturated monomer to be copolymerizable with these monomers. The obtained latex has 10-50 deg.C glass transition temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer paper, and more particularly to an electrophotographic transfer paper excellent in glossiness. More specifically, an aqueous polymer dispersion having an alkali-soluble polymer, and a base paper provided with gloss with a soap-free latex obtained by emulsion-polymerizing a monomer mixture in the presence of a neutralized product of an alkali-soluble polymer. The present invention relates to a transfer paper for electrophotography suitable for printing photographs, which is used for a full-color laser copy (hereinafter abbreviated as CLC) and a full-color laser beam printer (hereinafter abbreviated as CLBP), characterized by being coated with It is.

[0002]

2. Description of the Related Art With regard to transfer paper for electrophotography, in recent years, digital cameras having a resolution close to that of silver halide photography have rapidly spread, and as a result, image processing software using a personal computer has spread. The demand for an electrophotographic transfer paper from which a printed matter having a glossiness close to that of paper is obtained is rapidly increasing.

Hitherto, as a high-quality output medium, a sublimation type thermal transfer system has been preceded, and has been used in the field of image processing in medical treatment and the like. However, there is a problem that the sublimation type thermal transfer image receiving paper by this method is expensive and the time required for printing is long.

[0004] Recently, the image quality of printed matter by the ink jet system has been approaching that of photographic printing paper due to the dramatic improvement in resolution and the advancement of the technology for miniaturizing ink droplets. Photo printing systems have become commercially available. However, although the total cost of the inkjet method is low, the problem that the time required for the printing process is long has not been solved.

The electrophotographic method, which has a relatively low total cost and a short print processing time, has attracted attention as a printing method capable of obtaining image quality close to that of simple photographic printing paper. However, in the case of high-quality paper widely used as an electrophotographic transfer paper, the glossiness of the image portion to which the toner is transferred is higher than the blank glossiness of the non-image portion. The degree is low. Also, in the case of conventional glossy coated paper,
The glossiness of blank paper in the non-image area is lower than that of photographic paper. Furthermore, in the case of using a cast coat paper which is known to have a high blank gloss level, the blank gloss level of the non-image area increases,
There is a disadvantage that the glossiness of the image area is matte and the glossiness of the image area is lower than that of high quality paper.

On the other hand, soap-free latex is conventionally known to be produced by emulsion polymerization using a low-molecular-weight surfactant. However, these low-molecular-weight surfactants are used as emulsifiers for emulsion polymerization. When foaming is intense and handling is inconvenient, latex obtained by emulsion polymerization has low water resistance and low foaming resistance when used for transfer paper for electrophotography, and has poor film formability and stickiness. There was a problem that balance was not enough.

Further, when printing is performed by using CLC or CLBP, a model in which silicone oil is applied to the surface of the fixing roll in order to prevent toner transfer to the fixing roll when fixing the toner is generally used. There is also a problem with silicon oil resistance that white paper glossiness is reduced by silicone oil in the image area.

[0008] From the above-described circumstances, CLC, CL, etc., which maintain high glossiness even after printing, and include paper-passing properties.
There is a demand for electrophotographic transfer paper having good BP suitability.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high glossiness of blank paper before printing, a good resistance to silicon oil, and a glossiness of an image area even after printing by electrophotography. An object of the present invention is to provide a transfer paper for electrophotography, in which a printed matter having glossiness close to that of photographic printing paper is obtained without a decrease in blank glossiness of an unprinted portion and which is close to photographic printing paper.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have studied the use of a soap-free latex obtained by emulsion polymerization of a monomer mixture in the presence of a neutralized product of an alkali-soluble polymer. By coating on a base paper, an electrophotographic transfer paper excellent in glossiness of the present invention was invented.

That is, the transfer paper for electrophotography of the present invention is obtained by coating a coating composition containing a pigment and an adhesive as main components on at least one base paper surface and then applying a glossy base paper. And a soap-free latex coated on at least one surface of the base paper provided with gloss.

In the electrophotographic transfer paper of the present invention, the 75-degree specular glossiness specified by JIS P-8142 on the surface of the glossy base paper coated with soap-free latex is 90% or more. It is characterized by being.

[0013] Further, the soap-free latex to be coated in the present invention comprises two or more ethylenically unsaturated carboxylic acid ester monomers and an ethylenically unsaturated acid monomer, and a copolymer with these monomers. An ethylenically unsaturated carboxylic acid ester monomer, and copolymerizable with the ethylenically unsaturated carboxylic acid ester monomer in the presence of a partially or completely neutralized product of an alkali-soluble polymer composed of possible ethylenically unsaturated monomers. It is obtained by copolymerizing an unsaturated monomer mixture consisting of ethylenically unsaturated monomers, and has a glass transition temperature of latex of-
The temperature is 10 to 50C.

In the present invention, soap-free latex includes ethylenically unsaturated carboxylic acid ester monomers such as methyl acrylate and ethyl acrylate.
And methyl methacrylate.

In the present invention, the coating amount of the soap-free latex is preferably ^{2 to} 10 g / m ² (dry solid content).

Further, in the present invention, preferably, waste paper pulp is contained as base paper.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The transfer paper for electrophotography of the present invention will be described in detail below.

In the process of studying the glossiness of white paper after applying various aqueous coating liquids for the purpose of improving the surface smoothness and the glossiness, the present inventors have found that the smoothness of the base paper is important. After at least one of the base paper surfaces is coated with a coating composition containing a pigment and an adhesive as main components, a gloss-given base paper is formed, and a specific soap-free latex is applied to the base paper. It has been found that the glossiness of electrophotographic transfer paper is improved.

The base paper used in the present invention may be a photographic printing paper base paper having relatively good surface quality, but ordinary art base paper, coating base paper, etc., which are made by acidic, neutral or alkaline papermaking, are advantageously used. Can be

The pigments constituting the coating composition according to the present invention include various inorganic and organic pigments such as clay, talc, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, plastic One or more types of general coated paper pigments such as pigments are used.

Examples of the adhesive constituting the coating composition of the present invention include proteins such as casein, soybean protein, proteins extracted from single-cell assimilating cells such as methanol and acetic acid;
Gelatin, styrene-butadiene copolymer, conjugated diene-based polymer latex such as methyl methacrylate-butadiene copolymer, acrylic polymer latex such as acrylate and / or methacrylate polymer or copolymer, Vinyl-soluble polymer latex such as ethylene-vinyl acetate copolymer, or alkali-soluble or alkali-insoluble polymer latex obtained by modifying these various polymers with functional group-containing monomers such as carboxyl groups, olefins・ General coatings such as synthetic resin adhesives such as maleic anhydride resin and melamine resin, polyvinyl alcohol, positive starch, phosphated starch, starches such as oxidized starch, and cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose. Adhesive for paper There used alone or in combination.

As an auxiliary, an antifoaming agent, a coloring agent, a release agent, a fluidity improving agent, a printability improving agent, a water retention agent, a fluorescent dye and the like may be appropriately used as needed.

The coating composition containing a pigment and an adhesive in the present invention can be prepared by using a blade coater, an air knife coater, a roll coater, a film transfer coater, a curtain coater, a short dwell coater, and the like, which are used in the production of general coated paper. Coating is performed on the base paper in one or more layers by an on-machine or off-machine coater provided with a coating device such as a bar coater, a gravure coater, a gate roll coater, and a size press coater.

The coating amount of at least one of the base paper surfaces is about ² to 50 g / m ² in terms of dry weight, and the larger the coating amount, the better the glossiness of the electrophotographic transfer paper. However, the range of 5 to 35 g / m ² is preferable from the viewpoint of operability and quality.

The coated paper obtained by coating the coating composition on the base paper in this manner is then glossed by various glossing machines such as a super calender, a soft calender, a heat calender, a gloss calender and the like. After being applied, it is used as a base paper for electrophotographic transfer paper, and a super calendar and a soft calendar are preferred from the viewpoint of operability.

The pulp that can be used in the production of the base paper for the electrophotographic transfer paper of the present invention is a hardwood kraft pulp, a waste paper pulp, a natural pulp, a synthetic pulp, or a mixture of two or more. Can be used. As the natural pulp, any pulp usually used for papermaking can be used. That is, bleached chemical pulp such as softwood kraft pulp, hardwood sulfite pulp, and softwood sulfite pulp can be used. Further, mechanical pulp having high whiteness may be used. Further, non-wood pulp manufactured from grass fibers such as straw, esparto and kenaf, bast fibers such as bagasse, hemp, mulberry, ganpi, mitsumata, cotton and the like may be used.
Of these, bleached chemical pulp, such as softwood kraft pulp, hardwood kraft pulp, and softwood sulphite pulp, which are usually most frequently used industrially, is particularly preferred.

The pulp used in the base paper of the present invention includes:
Recovered paper pulp can also be preferably used. Recovered paper pulp is advantageous for the purpose of improving smoothness, because the fiber is given an appropriate flexibility during the reprocessing such as deinking and bleaching. The addition rate is preferably higher from the viewpoint of smoothness, but on the other hand, the stiffness of the base paper and the reduction in various strengths are accompanied.
Usually, the content is preferably 30 to 50% by weight of the total pulp amount, since the handling properties of the obtained electrophotographic transfer paper and the suitability for paper passage in CLC or CLBP are impaired.

The raw materials for waste paper pulp referred to in the present invention include: top white, ruled white, cream white, card, and the like shown in the waste paper standard quality standard table of the Waste Paper Recycling Promotion Center.
Special white, medium white, imitation, fair white, Kent, white art, special top cut,
Another example is newspaper, magazine, etc. Further specific examples include uncoated computer paper, which is information-related paper,
Printer paper such as thermal paper, pressure-sensitive paper (registered trademark), OA waste paper such as PPC paper, art paper, coated paper,
Coated paper such as lightly coated paper or matte paper, or high-quality paper, high-quality paper, notebooks, stationery, wrapping paper, fancy paper, medium-quality paper, newsprint, reprint, super-hanging paper, imitation paper, pure white roll paper Waste paper such as uncoated paper such as milk carton and paperboard, and chemical pulp paper and high-yield pulp-containing paper, etc., which are particularly limited regardless of printing, copying, printing and non-printing is not.

The beaten pulp slurry is made by a paper machine such as a fourdrinier paper machine, a twin wire paper machine, an on-top paper machine, a hybrid paper machine, or a round mesh paper machine. Additives such as a pulp slurry dispersing agent, a dry paper strength enhancer, a wet paper strength enhancer, a filler, a sizing agent, a fixing agent and an antifungal agent which are usually used in papermaking are added as necessary. Is possible.
Further, if necessary, a pH adjuster, a dye, a colored pigment, a fluorescent whitening agent and the like can be added.

Examples of the paper-strength enhancer include anionic paper-strength enhancers such as vegetable gum, starch and carboxy-modified polyvinyl alcohol; and cationic paper-strength such as cationized starch, cationic polyacrylamide and polyamide polyamine epichlorohydrin resin. Enhancers, as fillers, for example, clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, magnesium hydroxide, etc., as sizing agents, for example, higher fatty acid salts, rosin, maleated rosin Rosin derivatives such as, alkyl ketene dimer, alkenyl or alkyl succinate, epoxidized fatty acid amide, polysaccharide ester and the like, as a fixing agent, for example, aluminum sulfate, polyvalent metal salts such as aluminum chloride, cationized starch, Polyamide polya And cationic polymers such as emissions epichlorohydrin resin, as the pH adjusting agent include hydrochloric acid, sodium hydroxide, sodium carbonate and the like are used.

The surface properties of the base paper used in the present invention, such as size, can be improved by performing a surface treatment with a liquid containing various additives including a water-soluble polymer additive. It is.

Examples of the water-soluble polymer additive include completely saponified or partially saponified polyvinyl alcohol,
Modified products of polyvinyl alcohol such as cation modified, carboxy modified, silanol modified, starch and oxidized starch,
Carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, modified cellulose such as cellulose sulfate, gelatin, casein,
Pullulan, gum arabic, gum karaya, natural polymers such as albumin or derivatives thereof, polyacrylamide, polyvinylpyrrolidone, polypropylene glycol, polyethylene glycol, sodium polyacrylate, styrene-maleic anhydride copolymer sodium salt,
Synthetic polymers such as sodium polystyrene sulfonate are used, and further, as a sizing agent, petroleum resin emulsion, ammonium salt of styrene-maleic anhydride copolymer alkyl ester, alkyl ketene dimer emulsion, styrene-butadiene copolymer, Dispersion of ethylene-vinyl acetate copolymer, polyethylene, polyvinylidene chloride and the like are included. As other additives, as an antistatic agent, sodium chloride, calcium chloride, sodium sulfate, etc., which are inorganic electrolytes; as a hygroscopic substance, glycerin, polyethylene glycol, etc .; as a pigment, clay, kaolin, talc, Barium sulfate, titanium oxide and the like are used as a pH adjuster, such as hydrochloric acid, sodium hydroxide, and sodium carbonate. Other additives such as a dye and an optical brightener can also be used in combination.

As a device for applying the above-mentioned binder and surface sizing agent, a conventional size press, a gate roll size press, a film transfer type size press, a rod coater, a bill blade, a short dwell coater and the like can be used. it can.

The thickness of the base paper of the electrophotographic transfer paper of the present invention is not particularly limited, but the basis weight is 50 to 200 g / m ^2.
Is preferred. When the grammage is less than 50 g / m ² , the rigidity is too low, so that the paper passing suitability of CLC and CLBP cannot be obtained. On the other hand, when the basis weight exceeds 200 g / m ² , on the contrary, the rigidity is too high, and there is a problem in the suitability of CLC and CLBP for paper passing.

Further, the soap-free latex used in the electrophotographic transfer paper of the present invention will be specifically described below.

In the present invention, the following soap-free latex is used. Generally, a low molecular weight emulsifier is used as an emulsion stabilizer in the production of latex.
The flow characteristics of latex stabilized with a general low-molecular weight emulsifier show structural viscosity, and the mixing stability with various solvents and resins is not sufficient, and the range of use is limited in applications such as coating and printing. Would be done. In the present invention, since the smoothness of the coated surface is largely controlled by the fluidity of the latex itself and the surface quality of the base paper, the smoothness of the coated surface has no structural viscosity as described in JP-A-6-271779. It is preferred to use soap-free latex.

When a general latex is dried, the emulsifier inhibits the formation of polymer particles in the latex solution, or the released emulsifier migrates to the surface after the formation of the film, resulting in adhesion to various materials. And the adhesiveness tends to decrease. In the transfer paper for electrophotography of the present invention, by using a new soap-free latex, the affinity between the surface of the transfer paper for electrophotography and the toner and the adhesiveness are improved, so that the target quality can be improved. It became possible to obtain.

More specifically, the soap-free latex according to the present invention comprises two or more ethylenically unsaturated carboxylic acid ester monomers having a solubility of 0.5% or more in water at 20 ° C. of the homopolymer. ７０70% by weight, and 5-40% by weight of an ethylenically unsaturated acid monomer,
And in the presence of a partially or completely neutralized product of an alkali-soluble polymer consisting of 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable with these monomers, Carboxylic acid ester monomer 70-100
And a glass transition temperature of the latex obtained by copolymerizing an unsaturated monomer mixture consisting of 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable therewith,
Soap-free latex at 10 to 50 ° C is preferably used.

The solubility of the monomer in water at 20 ° C. and the glass transition temperature of the homopolymer in the present invention are described in Polymer Handbook J. BRAN
DRUF / E. H. It was obtained from IMMERGUT. Further, the glass transition temperature Tg of the copolymer was determined by the following equation (1).

[0040]

1 / Tg = W1 / Tg1 + W2 / Tg2 +... Wn / Tgn (Equation 2) Tg: Glass transition temperature of copolymer (K) Tg1, Tg2. Glass transition temperature (K) W1, W2 ...: weight fraction of each component

The solubility of typical ethylenically unsaturated carboxylic acid ester monomers in water and the glass transition temperature of the homopolymer are as shown in Table 1 below.

[0042]

[Table 1]

According to the present invention, 20 of these homopolymers
Two or more types of ethylenically unsaturated carboxylic acid ester monomers having a solubility in water of at least 0.5%
0 parts by weight can be used.

When an ethylenically unsaturated carboxylic acid ester monomer having a solubility in water of 0.5% or less is used, the alkali solubility of the polymerization product is reduced, and it becomes difficult to carry out the emulsion polymerization stably.

As the ethylenically unsaturated carboxylic acid ester monomer used in the present invention, methyl acrylate, methyl methacrylate and ethyl acrylate are preferred.

The ethylenically unsaturated acid monomers used in the present invention include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; fumaric acid, maleic acid, itaconic acid and butenetricarboxylic acid. Examples include ethylenically unsaturated polycarboxylic acids; partially esterified ethylenically unsaturated polycarboxylic acids such as monoethyl maleate and monomethyl itaconate; and ethylenically unsaturated sulfonic acids such as vinyl sulfonic acid. Among these ethylenically unsaturated acid monomers, ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid are preferred.

These ethylenically unsaturated acid monomers can be used in an amount of 5 to 40 parts by weight, preferably 10 to 40 parts by weight. When the number of parts of the ethylenically unsaturated acid monomer used is 5 parts by weight or less, alkali solubility is reduced, and it becomes difficult to stably advance emulsion polymerization.

When the amount of the ethylenically unsaturated acid monomer is at least 40 parts by weight, the viscosity of the polymer increases, and it becomes difficult to carry out the emulsion polymerization stably.

Other ethylenically unsaturated monomers that can be copolymerized include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene and chlorostyrene;
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, (meth)
Ethylenically unsaturated carboxylic acid esters such as hexyl acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate (Meth) acrylonitrile and other cyano group-containing ethylenically unsaturated monomers; ethylenically unsaturated glycidyl ethers such as allyl glycidyl ether; (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl ( Ethylenically unsaturated amide monomers such as (meth) acrylamide; conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene; vinyl acetate Carboxylic acid vinyl esters; It is.

Among these monomers, ethylenically unsaturated carboxylic acid ester monomers such as methyl (meth) acrylate and ethyl (meth) acrylate are preferred.

These monomers can be used in a proportion of 0 to 30 parts by weight, more preferably 0 to 20 parts by weight.

When the use ratio of these monomers exceeds 30 parts by weight, the compatibility balance is lost, and the transparency and glossiness of the polymer coating layer when dried are reduced.

In producing the alkali-soluble polymer,
If necessary, a molecular weight modifier can be used at the time of polymerization. Mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan;
α-methylstyrene dimer; sulfides such as dimethyl xanthogen disulfide and diisopropylxanthogen disulfide; nitrile compounds such as 2-methyl-3-butenenitrile and 3-pentenenitrile; methyl thioglycolate, propyl thioglycolate, and octyl thioglycolate Thioglycolic acid esters such as methyl β-mercaptopropionate and octyl β-mercaptopropionate; and these can be used alone or in combination of two or more. Of these molecular weight regulators, thioglycolic acid esters are preferred.

In producing the alkali-soluble polymer,
Polymerizable surfactants can be used. Polymerizable surfactants are surfactants having one or more polymerizable vinyl groups in the molecule. Specific examples thereof include sodium propenyl-2-ethylhexylsulfosuccinate, polyoxyethylene sulfate (meth) acrylate, ammonium salt of polyoxyethylene alkylpropenyl ether sulfate, and polyoxyethylene ester (meth) acrylate. Nonionic polymerizable surfactants such as polyoxyethylene alkyl benzene ether (meth) acrylate and polyoxyethylene alkyl ether (meth) acrylate; and the like. Among these polymerizable surfactants, ammonium polyoxyethylene alkyl propenyl ether sulfate is preferred because of its excellent balance between the emulsifying and dispersing performance of the monomer and the copolymerizability with the monomer.

The basic substance used to neutralize the alkali-soluble polymer includes ammonia; methylamine, ethylamine, isopropylamine, dimethylamine, N, N-dimethylethanolamine, diisopropylamine, trimethylamine, triethanolamine and the like. Amines; hydroxides of alkali metals such as sodium hydroxide; and the like. Of these, ammonia is preferred. The amount of the basic substance used is such that the degree of neutralization of the alkali-soluble oligomer is usually 70% or more.

The glass transition temperature of the finally obtained soap-free latex is from -10 ° C to 50 ° C. When the glass transition temperature of the aqueous polymer is lower than -10 ° C, stickiness occurs on the surface of the electrophotographic transfer paper, and blocking tends to occur when the electrophotographic transfer paper is stacked. When the glass transition temperature exceeds 50 ° C., cracks occur due to a decrease in the film forming property of the coating layer, and the smoothness and glossiness of the surface are liable to decrease.

The amount of the soap-free latex applied to the base paper is preferably ² to 10 g / m ² (dry solid content) on one side. When the coating amount is less than 2 g / m ² , the covering by coating of the base paper is incomplete and a sufficient gloss value cannot be obtained. On the other hand, the coating amount was 10 g / m ²
Even with the above, the glossiness obtained is saturated, which is not economically favorable, and the thickness of the coating layer becomes excessively large, so that the curl of the product tends to increase and the stickiness of the coating surface tends to increase.

The transfer paper for electrophotography of the present invention can be basically obtained by coating the above-mentioned soap-free latex of the present invention. Widely used toning agents such as pigments, dyes and fluorescent whitening agents, antistatic agents, cationic resin and other surfaces, and water-resistance improvers for image areas can be added in appropriate combinations. It is.

Examples of the apparatus for applying the above-mentioned soap-free latex to the base paper in the present invention include a gate roll coater or a film transfer coater, a rod coater, an air knife coater, a blade coater, a bill blade coater, a short dwell coater, A coating device such as a curtain coater can be used. Among these coating devices, it is desirable to use a system in which the penetration into the base paper layer is as small as possible. Further, after the coating, if necessary, it is also possible to perform a smoothing finish using a calendar device such as a machine calender, a heat calender, a super calender, and a soft calender.

The transfer paper for electrophotography in the present invention is CL
It can be used not only as transfer paper for electrophotography for C and CLBP but also as offset printing paper and thermal transfer image receiving paper. Also, on the opposite side of printing use,
It is also possible to apply an adhesive layer and apply it to label use.

[0061]

Next, the present invention will be described in more detail by way of examples. However, it is not limited to these.
The parts and percentages shown below are based on weight, and the coating amount is a dry coating amount.

Examples 1 to 14 <Preparation of base paper 1> Hardwood bleached kraft pulp (LBKP)
And conifer bleached kraft pulp (NBKP) are separately dispersed in water at a concentration of 4%, and the freeness is Canadian Standard Free using a double disc refiner.
The mixture was beaten to 440 ml and 490 ml with a Nes tester. Hardwood bleached kraft pulp: softwood bleached kraft pulp
The mixture was mixed at 70:30. In this mixed pulp slurry, 0.03% of alkyl ketene dimer to pulp as a sizing agent, 6% of pulp to light calcium carbonate as filler, 1.2% of pulp to cationized starch, and 0.1% of sulphate band to pulp. 4% was added and diluted with water to obtain a 1% slurry. This slurry was mixed with a retention aid against pulp 2
50 ppm was added, papermaking was performed by a fourdrinier paper machine so as to have a basis weight of 54 g / m ^2, and a size press solution having a concentration of 6% oxidized starch was applied by a size press to obtain base paper 1.

<Preparation of base paper 2> A base paper was prepared in the same manner except that the pulp composition of base paper 1 was mixed so that the hardwood bleached kraft pulp: softwood bleached kraft pulp: used paper pulp = 30:30:40 in terms of solid content. This was used as base paper 2.

<Preparation of base paper 3> The basis weight of base paper 1 was 56 g /
was changed to m ² was stencil 3 which was prepared base paper in the same manner.

<Preparation of base paper 4> The hardwood bleached kraft pulp (LBKP) and the softwood bleached kraft pulp (NBKP) were separately dispersed in water at a concentration of 4% by mixing the pulp of the base paper 1 with a double disc refiner. The mixture was beaten with a Canadian Standard Freeness Tester to 380 ml and 490 ml, respectively.
Base paper was prepared in the same manner except that this pulp slurry was mixed in such a manner that hardwood bleached kraft pulp: softwood bleached kraft pulp = 80: 20 in terms of solid content.

The composition of the undercoat liquid used in the present invention is shown below. <Undercoat liquid formulation> Commercial heavy calcium carbonate slurry (WH-70) 100 parts Commercial phosphorylated starch 9 parts Commercial styrene / butadiene latex 8 parts Ammonia water 0.1 parts Calcium stearate 0.45 parts

The composition of the overcoat liquid 1 used in the present invention is shown below. The solid content concentration of the overcoat liquid 1 was 64%. <1 top coating liquid> Commercial heavy calcium carbonate (Carbital 90) 50 parts Commercial primary kaolin (Ultra White 90) 50 parts Commercial polyacrylic acid dispersant 0.2 parts Commercial printability improver (SR713B manufactured by Sumitomo Chemical) 0.8 parts Commercial water retention agent (Alcogum L-29 manufactured by Alcochemical) 0.1 parts Commercially phosphorylated starch 2.0 parts Commercially available styrene / butadiene latex 13.0 parts Ammonia water 0.2 parts Calcium stearate 0.45 Department

The composition of the overcoat liquid 2 used in the present invention is shown below. The solid concentration of the overcoat liquid 2 was 65%. <Composition of overcoating liquid 2> Commercial heavy calcium carbonate (Carbital 90) 50 parts Commercial primary kaolin (DB prime) 40 parts Commercial secondary kaolin (HS kaolin) 10 parts Commercial polyacrylic acid dispersant 0.1 part Commercial printing Suitability improver (SR713Q, manufactured by Sumitomo Chemical) 0.3 part Commercial water retention agent (Alcogum L-29 manufactured by Alcochemical) 0.06 part Commercially available phosphorylated starch 2.5 parts Commercially available styrene / butadiene latex 10.5 parts Ammonia water 0.2 parts Calcium stearate 0.45 parts

The formulation of the overcoat liquid 3 used in the present invention is shown below. The solid content concentration of the overcoat liquid 3 was 49%. <Composition of Topcoat Liquid 3> Commercially available heavy calcium carbonate (Carbital 90) 10 parts Commercially available light calcium carbonate (Brilliant 15) 10 parts Commercially available primary kaolin (Ultra White 90) 50 parts Commercially available secondary kaolin (Hydrasperse) 23 parts Commercially available sachin White 7 parts Commercially available polyacrylic acid-based dispersant 0.4 part Commercially available printability improver (SR636 manufactured by Sumitomo Chemical) 0.5 part Commercially available phosphorylated starch 3.0 parts Commercially available styrene / butadiene latex 17.0 parts Ammonia water 0.2 parts Calcium stearate 0.45 parts

The following is an example of producing the soap-free latex used in the present invention. <Production Example 1> 46 parts of ethyl acrylate, 26 parts of methyl methacrylate, 28 parts of methacrylic acid, 8.0 parts of octyl thioglycolate, a polymerizable surfactant (polyoxyethylene alkylpropenyl ether sulfate ammonium salt, Aqualon HS10, 2 parts of Ichi Kogyo Seiyaku Co., Ltd.) and 45 parts of ion-exchanged water were mixed and dispersed to obtain a monomer emulsion. On the other hand, after replacing the inside of the reactor with a stirrer with nitrogen,
90 parts of ion-exchanged water is charged and heated to 80 ° C., and 40 parts of a 5% aqueous solution of potassium persulfate is added to the reactor, and then the monomer emulsion is continuously added to the reactor maintained at 80 ° C. over 2 hours. And reacted. After the addition of the monomer emulsion, the reaction was further performed for 1 hour to obtain an aqueous dispersion of an alkali-soluble polymer. 19.3 parts of 28% aqueous ammonia and 43 parts of ion-exchanged water were added to the obtained aqueous dispersion to obtain an alkaline aqueous solution having a solid content of 32%.

While stirring 300 parts of the obtained alkali-soluble polymer aqueous alkali solution at 80 ° C. while stirring, 20 parts of a 3% aqueous solution of potassium persulfate was added. In time,
After the addition of the monomer is completed, the mixture is further reacted for 2 hours and cooled,
The pH was adjusted to 8 with ammonia to obtain a soap-free latex having a solid content of 38%. The glass transition temperature of the soap-free latex of Example 1 was 17 ° C., which was within the range specified by the present invention.

<Production Examples 2-5> Production Examples 2-5 were soap-free in the same manner as in Production Example 1 except that the monomer mixture was replaced with a neutralized product or a monomer mixture shown in Table 2. Latex was obtained.

The results of these evaluations are shown in Table 2 below. The glass transition temperature of the aqueous dispersion of Production Example 2 was 32 ° C., which was within the range specified by the present invention. The glass transition temperature of the soap-free latex of Production Example 3 is −8 ° C.
Which was within the range defined by the present invention. The glass transition temperature of the soap-free latex of Production Example 4 was 52
° C, which was out of the range defined by the present invention. The glass transition temperature of the soap-free latex of Production Example 5 was −
The temperature was 14 ° C., which was outside the range defined by the present invention.

[Characteristics of soap-free latex] (Amount of coagulated material) A soap-free latex having a solid content of 25% was filtered through a 200-mesh wire net, and the solidified material remaining on the wire mesh was dried in an infrared oven to obtain a constant weight value. It was expressed as a percentage by weight based on the solid content of the soap-free latex.

[0075]

[Table 2]

Examples 1 and 2 The above-mentioned base paper 1 was coated with a top coat solution 1 on both sides by 14 g / m ^{2 on} each side with a blade coater and dried, and then the coated paper was subjected to a linear pressure of 30 kg / cm and 10 nip. , Processing speed 35
Under the condition of 0 m / min, an actual machine was subjected to a super calendar treatment to obtain a base paper having a white paper gloss of 65%. Production Example 1
Soap-free latex with a blade coater on one side 5
g / m ^{2 was} applied, and this paper was used as Example 1. In the second embodiment, the super calender processing of the first embodiment is performed by using a test coater online soft calender (rigid roll: outer diameter 50).
(0 mm chilled roll, elastic roll: resin roll with an outer diameter of 500 mm, linear pressure: 80 kg / cm, temperature: 80 ° C.) and changed to soft calendering to give a white paper gloss of 6
Example 2 was made in the same manner except that 6% of the base paper was obtained.

Example 3 An undercoat solution was applied to the base paper 4 with a blade coater at 5.5 g / g.
After coating on both sides of m ² and drying, 8.5 g / m ^{2 of} the top coating liquid 3 was applied on both sides by an air knife coater, and the coated paper was applied at a linear pressure of 30 kg / cm, 10 nip, and a processing speed of 350 g / m ^2.
Under the conditions of m / min, supercalendering was performed on an actual machine to obtain a base paper having a white paper glossiness of 75%. 5 g of one side of the soap-free latex of Production Example 1 on this base paper using a blade coater
/ m ² , and this paper was used as Example 3.

Example 4 The base paper 3 was coated with a top coat liquid 3 on both sides by 12 g / m ^{2 on} each side with a blade coater and dried, and the coated paper was treated at a linear pressure of 30 kg / cm, 10 nip, and treated. Speed 35
Under the conditions of 0 m / min, the actual paper was subjected to a super calendar treatment to obtain a base paper having a white paper glossiness of 60%. Production Example 1
Soap-free latex with a blade coater on one side 5
g / m ^{2 was} applied, and this paper was used as Example 4.

Example 5 The above-mentioned base paper 2 was coated with a top coat solution 1 on both sides 14 g / m ^{2 on} each side by a blade coater and dried, and then the coated paper was subjected to a linear pressure of 30 kg / cm and a processing speed of 100 m. / Min
The actual paper was subjected to a super calendar treatment under the conditions described above to obtain a base paper having a white paper glossiness of 66%. The base paper was coated with the soap-free latex of Production Example 1 at a rate of 5 g / m ² on one side using a blade coater.

Example 6 The soap-free latex of Production Example 1 according to Example 1 was coated on one side at a coating amount of 5.5 g / m ² and dried to prepare an electrophotographic transfer paper.

Example 7 The soap-free latex of Example 6 was changed to Production Example 2 and coated and dried to prepare an electrophotographic transfer paper.

Example 8 The soap-free latex of Example 6 was changed to Production Example 3 and coated and dried to prepare an electrophotographic transfer paper.

Example 9 The soap-free latex of Example 6 was changed to that of Production Example 4 and coated and dried to prepare an electrophotographic transfer paper.

Example 10 The soap-free latex of Example 6 was changed to Production Example 5 and coated and dried to prepare an electrophotographic transfer paper.

Example 11 In Example 1, the soap-free latex was coated at a coating amount of 2.1 g /
coating so that the m ^2, followed by drying to produce a transfer paper for electrophotography.

Example 12 In Example 1, the soap-free latex was applied at a coating amount of 9.8 g /
coating so that the m ^2, followed by drying to produce a transfer paper for electrophotography.

Example 13 The amount of the soap-free latex applied in Example 1 was 19.4 g.
/ m ² and dried to produce an electrophotographic transfer paper.

Example 14 The amount of one-side application of soap-free latex in Example 1 was 5.5.
g / m ² was applied to both sides and dried to produce an electrophotographic transfer paper.

Comparative Example 1 Using the base paper 1 as a base paper, the soap-free latex of Production Example 1 was coated on the base paper with a blade coater at a rate of 5 g / m ² on one side.

Comparative Example 2 Production was performed in the same manner as in Example 1 except that the soap-free latex for coating the base paper was replaced with a commercially available styrene-butadiene latex (P-6945, manufactured by Sumika A & L) for commercial use. Then, Comparative Example 2 was obtained.

Comparative Example 3 A commercial styrene / butadiene latex for commercial use (P-6945, manufactured by Sumika A & L) was used in place of the soap-free latex for coating the base paper in Example 2, and the coating amount was 10 g / l. except that the m ² was prepared in the same manner to obtain a comparative example 3.

Comparative Example 4 Comparative Example 4 was produced in the same manner as in Example 1 except that the supercalender treatment was not performed on the base paper.

Comparative Example 5 A commercially available vinyl chloride-acrylic copolymer emulsion (Vinibulan 609 manufactured by Nissin Chemical Industry Co., Ltd.) was used in place of the soap-free latex for coating the base paper in Example 1, and the coating amount was 20 g. Comparative Example 5 was obtained in the same manner except that the amount was changed to / m ² .

The above Examples 1 to 14 and Comparative Examples 1 to 5
The electrophotographic transfer paper prepared in the above was evaluated by the following test method. The results of the evaluation are shown in Table 3 below.

<White Paper Gloss> The white paper gloss was measured according to JIS after conditioning a sample under an environment of 20 ° C. and 65% RH for 24 hours.
The specular glossiness at 75 degrees was measured according to P-8142.
In the present invention, it is desirable that the glossiness of blank paper is 85% or more. In the measurement, FUJI Xerox
Manufactured by: A blank paper portion of the electrophotographic transfer paper before and after passing the A-Color 935 machine, and is shown as before printing and after printing.

<Glossiness of Printed Area> The glossiness of the printed area is FUJ
I Xerox: A-Color935 machine, in cardboard mode, TEST CHART TYPE of the Printing Society
Using E1, a sample printed by passing a blank A4 size white paper sample through it was irradiated with oblique light, and the glossiness was visually compared with that of a photographic printing paper. “◎”: No problem at all. "〇": Available for practical use. "△": There is a practical problem. “×”: Not available.

<Toner Fixing Property> Toner fixing property is determined by FUJ
I Xerox: A-Color935 machine, in cardboard mode, TEST CHART TYPE of the Printing Society
Using a sample printed by passing an A4 size vertical blank paper sample using E1, a Nichiban cellophane adhesive tape "Cellotape No. 405" having a width of 18 mm is applied so that unevenness does not occur in the printed portion of each color. After pasting, 180
The tape was slowly peeled off at a speed of about 5 mm / sec, and the degree of fixing of the toner to the paper after peeling was visually determined. The evaluation was performed on a 6-point scale based on the following criteria.
The level at which there is no practical problem is “4” or more. “6”: Most of the toner remains on the paper for each color. "5": It can be seen that the toner remains on the paper for each color, but the print density of the printed portion after the tape has been peeled is reduced. "4": The toner peeled off from the paper in some colors, and a white portion was observed in the printed portion. "3": The toner peeled off from the paper for each color, and a white portion was observed in the printed portion. "2": The toner peels off the paper for each color, and the toner slightly remains on the paper. "1": The toner is peeled off from the paper for each color, and no printed portion remains.

<Paper-passing property> Regarding the paper-passing property of the transfer paper for electrophotography in a printing machine, the copying machine “NP625” manufactured by Canon Inc. was used.
The evaluation was performed using “0”. As a test for paper feedability,
One-sided printing was performed on 500 sheets of A4 size electrophotographic transfer paper, and the number of paper jams in the copying machine during printing was measured. The number of times of paper jam is a practical level if it is not more than once after passing 500 sheets.

<Stackiness> The stickiness of the blank sample was
The measurement sample was conditioned in an environment of 20 ° C. and 65% RH for 24 hours, washed thoroughly with soap, and then sandwiched between the dried thumb and forefinger three times. Was evaluated on a 4-point scale. “◎”: No problem at all. "〇": Available for practical use. "△": There is a practical problem. “×”: Not available.

[0100]

[Table 3]

As is clear from the above Examples 1 to 14,
By applying the soap-free latex of the present invention to a coated paper exhibiting a certain gloss value, an electrophotographic paper having a high gloss can be obtained. Further, even if the coated base paper is used as a base paper as in Comparative Example 1, a high glossiness comparable to a photographic paper photograph cannot be obtained. Further, even if the coated paper is not provided with a gloss as shown in Comparative Example 4, even if a soap-free latex is applied, a sufficient gloss cannot be obtained. In Comparative Examples 2, 3, and 5, a commercially available emulsion having a film-forming ability was applied instead of the soap-free latex, but it can be seen that sufficient gloss could not be obtained even with this.

[0102]

As described above, the electrophotographic transfer paper coated with a certain amount of the soap-free latex of the present invention has a high white paper glossiness only when the base paper specified by the present invention and the soap-free latex are used. As a result, all of the various properties, including the first, are improved in a well-balanced manner, so that it is possible to obtain an electrophotographic transfer paper capable of obtaining a printed matter at a level close to that of photographic printing paper.

Claims (6)

[Claims] 1. A base paper provided with a gloss after a coating composition containing a pigment and an adhesive as a main component is applied to at least one base paper surface, and the gloss of the base paper is provided. An electrophotographic transfer paper, wherein at least one surface is coated with a soap-free latex. 2. The electrophotographic transfer paper according to claim 1, wherein the surface coated with the soap-free latex has a 75 ° specular glossiness specified by JIS P-8142 of 90% or more. 3. A soap-free latex comprising two or more ethylenically unsaturated carboxylic acid ester monomers, an ethylenically unsaturated acid monomer, and an ethylenically unsaturated copolymerizable with these monomers. An ethylenically unsaturated carboxylic acid ester monomer in the presence of a partially or completely neutralized product of an alkali-soluble polymer composed of a monomer,
And a copolymer obtained by copolymerizing an unsaturated monomer mixture comprising an ethylenically unsaturated monomer copolymerizable therewith, and having a glass transition temperature of the latex of -10 to 50 ° C. The transfer paper for electrophotography according to claim 1. 4. The transfer paper for electrophotography according to claim 3, wherein the ethylenically unsaturated carboxylic acid ester monomer is selected from the group consisting of methyl acrylate, ethyl acrylate, and methyl methacrylate. 5. The coating amount of the soap-free latex is 2
To 10 g / m ² transfer paper for electrophotography according to any one of claims 1-4, characterized in that the (dry solids). 6. The transfer paper for electrophotography according to claim 1, wherein the base paper contains waste paper pulp.