JP2000319310A - Aqueous polymer dispersion, method for producing the same, and transfer paper for electrophotography using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous polymer dispersion having a high gloss when dried, a method for producing the same, and a high gloss before printing, good silicone oil resistance, and electrophotographic printing. After the printing, the gloss of the image portion after printing and the blank gloss of the unprinted portion do not decrease, so that a printed matter having a gloss close to that of the photographic printing paper with a glossy surface can be obtained. In particular, electrophotographic transfer paper suitable for printing photographs SOLUTION: An aqueous polymer dispersion comprising an ethylenically unsaturated carboxylic acid ester monomer having a difference in SP value of a homopolymer of 0.5 or less, a method for producing the same, and a center plane average roughness The glass transition temperature manufactured by the method defined in the present invention is -10 to 50 on at least one surface of the base paper having (SRa) of 1.5 m or less and a film thickness unevenness index (Rpy) of 250 mV or less. Electrophotographic transfer paper formed by applying a coating fluid containing an aqueous polymer dispersion is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous polymer dispersion, a method for producing the same, and an electrophotographic transfer paper using the same. More specifically, a method for producing an aqueous polymer dispersion having an alkali-soluble polymer, an aqueous polymer dispersion in which a monomer mixture is emulsion-polymerized in the presence of a neutralized product of an alkali-soluble polymer, and a full-color laser copy (hereinafter, referred to as an aqueous polymer dispersion) , CLC) and full-color laser beam printer (hereinafter abbreviated as CLBP)
The image area where the toner is transferred after printing,
In addition, the present invention relates to an electrophotographic transfer paper which has a high glossiness of a blank portion and a glossy surface close to that of a photographic printing paper with a glossy surface, and is particularly suitable for printing photographs.

[0002]

2. Description of the Related Art An aqueous polymer dispersion is conventionally known which is produced by emulsion polymerization using a low-molecular-weight surfactant. However, these low-molecular-weight surfactants are used as an emulsifier for emulsion polymerization. When used as, foaming is intense and handling is inconvenient, and the aqueous polymer dispersion obtained by emulsion polymerization is used for electrophotographic transfer paper,
There is a problem that the water resistance and the defoaming property are low and the balance between the film forming property and the stickiness is not sufficient.

On the other hand, 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 image processing software using personal computers has spread along with this. There is a rapidly growing demand for electrophotographic transfer paper that can provide printed matter having a gloss close to that of photographic printing paper.

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 is expensive and the time required for printing is long.

[0005] Recently, the image quality of printed matter by an ink jet printer 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 a simple photographic printing paper. However, in the case of high quality paper widely used as transfer paper for electrophotography, the gloss of the image area to which the toner has been transferred is higher than that of the non-image area, but the gloss of the non-image area is naturally low. Also, in the case of the conventional glossy coated paper, the glossiness of the blank image in the non-image area is not as high as that of the glossy surface photographic paper. Furthermore, in the case of using a cast-coated paper which is known to have high blank gloss, the blank gloss of the non-image portion is high, but the toner gloss of the image portion is matte, and compared with the case of high quality paper. There is a disadvantage that gloss is reduced.

Further, when printing is performed 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 that the gloss is reduced by the silicone oil in the portion.

[0008] From the above-mentioned situation, CLC, CLB, etc., which maintain high gloss even after printing, and have paper-passing properties.
There is a demand for electrophotographic transfer paper having good P suitability.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous polymer dispersion having high emulsion stabilization performance, water resistance and foam suppressing property, and a method for producing such an aqueous polymer dispersion. In addition, the gloss before printing is high, and the silicone oil resistance is good. Even after printing by electrophotography, the gloss of the image area after printing and the glossiness of blank paper in the unprinted area do not decrease, and the glossy surface It is an object of the present invention to provide an electrophotographic transfer paper which can obtain a printed matter having a gloss close to that of photographic printing paper and is particularly suitable for printing photographs.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have invented an aqueous polymer dispersion of the present invention, a method for producing the aqueous polymer dispersion, and an electrophotographic transfer paper using the same. I came to.

That is, the aqueous polymer dispersion of the present invention has a homopolymer having an SP value of 7 (Cal / cm ³ ) ^1/2 or more,
A difference of 0.5 or less, two or more ethylenically unsaturated carboxylic acid ester monomers having a solubility in water at 20 ° C. of 0.5% or more, 40 to 70% by weight, and ethylenically unsaturated 5 to 40% by weight of an acid monomer, and 0 ethylenically unsaturated monomers copolymerizable with these monomers.
70 to 100% by weight of the ethylenically unsaturated carboxylic acid ester monomer in the presence of a partially or completely neutralized product of an alkali-soluble polymer consisting of Ethylenically unsaturated monomer 0
The glass transition temperature obtained by copolymerizing an unsaturated monomer mixture consisting of 30% by weight is -10 to 50C.

In the aqueous polymer dispersion of the present invention, the ethylenically unsaturated carboxylic acid ester monomer is selected from methyl acrylate, ethyl acrylate and methyl methacrylate.

In the method for producing an aqueous polymer dispersion of the present invention, the solubility in water at 20 ° C. is 0.5% or more, and the SP value of the homopolymer is 7 (Cal / cm ³ ) ^1/2. And at least two types of ethylenically unsaturated carboxylic acid ester monomers 40 to 70 having a difference of 0.5 or less.
% Of an ethylenically unsaturated acid monomer and 5 to 40% by weight of an ethylenically unsaturated acid monomer, and 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable with these monomers. Or in the presence of complete or neutralized
The solubility in water at 20 ° C. is 0.5% or more, and the SP value of the homopolymer is 7 (Cal / cm ³ ) ^1/2 or more,
70 to 100% by weight of an ethylenically unsaturated carboxylic acid ester monomer having a difference of 0.5 or less, and 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable therewith.
Wherein the glass transition temperature of the polymer obtained by copolymerizing an unsaturated monomer mixture comprising the following is -10 to 50C.

Further, the electrophotographic transfer paper of the present invention has at least one surface of a base paper having a center plane average roughness (SRa) of 1.5 μm or less and a thickness unevenness index (Rpy) of 250 mV or less. Further, a coating layer is provided by applying a coating liquid containing the above aqueous polymer dispersion.

The electrophotographic transfer paper of the present invention is characterized in that the glossiness of the coated layer surface is 75% or more.

In the present invention, the coating amount of the aqueous polymer dispersion is preferably from 5 to ²⁰ g / m ² (dry solid content).

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

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous polymer dispersion of the present invention, the method for producing the same, and the transfer paper for electrophotography will be described in detail below.

According to the present invention, the homopolymer has an SP value of 7
(Cal / cm ³ ) ^1/2 or more, and the difference is 0.5
The following are 40 to 70% by weight of two or more ethylenically unsaturated carboxylic acid ester monomers having a solubility in water at 20 ° C of 0.5% or more, and 5 to 40% by weight of ethylenically unsaturated acid monomers. 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. Obtained by copolymerizing an unsaturated monomer mixture consisting of 70 to 100% by weight of an unsaturated carboxylic acid ester monomer and 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable therewith, An aqueous polymer dispersion having a glass transition temperature of -10 to 50 ° C and a method for producing the same are provided.

The SP value of the polymer in the present invention means a solubility parameter, and is a value determined by the following equation (1).

SP value = {(35.6T-5130) / M} ^1/2 (Formula 1) T: Boiling point (K) of monomer M: Molecular weight of monomer

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 (2).

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

Table 1 below shows the SP value, the solubility in water, and the glass transition temperature of a homopolymer of typical ethylenically unsaturated carboxylic acid ester monomers.

[0025]

[Table 1]

According to the present invention, the SP of these homopolymers
Value of 7 (Cal / cm ³ ) ^1/2 or more, and the difference is 0.5 or less.
% Or more of 40 to 70 parts by weight of two or more ethylenically unsaturated carboxylic acid ester monomers.

The SP value of the homopolymer is 7 (Cal / c
When an ethylenically unsaturated carboxylic acid ester monomer having an m ³ ) of ^1/2 or less is used, the alkali solubility of the polymerization product is reduced, and it becomes difficult to carry out emulsion polymerization stably. In addition, SP of ethylenically unsaturated carboxylic acid ester polymer
When the difference between the values exceeds 0.5, the compatibility is reduced, and the transparency and gloss of the polymer coating layer when dried are reduced.

Further, 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 is 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.

The amount of the ethylenically unsaturated acid monomer used is 5 to 40 parts by weight, preferably 10 to 40 parts by weight. When the amount is 5 parts by weight or less, alkali solubility is reduced, and it becomes difficult to stably perform emulsion polymerization.

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

Other copolymerizable ethylenically unsaturated monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene and chlorostyrene; methyl (meth) acrylate, (meth) acrylic Ethyl acid,
Propyl (meth) acrylate, n- (meth) acrylate
Amyl, isoamyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate,
Ethylenic unsaturated carboxylic acid ester monomers such as octyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate; cyano groups such as (meth) acrylonitrile Containing ethylenically unsaturated monomer; ethylenically unsaturated glycidyl ether such as allyl glycidyl ether; ethylenically unsaturated amide such as (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide Monomer; 1,3
-Butadiene, isoprene, 2,3-dimethyl-1,3
-Conjugated diene monomers such as butadiene and 1,3-pentadiene; carboxylic acid vinyl esters such as vinyl acetate; and the like.

Of 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.

If the proportion of these monomers exceeds 30 parts by weight, the compatibility balance is lost, and the transparency and gloss 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 alkylpropenyl ether sulfate is preferred because it has an excellent balance between the emulsifying and dispersing performance of the monomer and the copolymerizability with the monomer.

The basic substance used for neutralizing 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.

In the present invention, the alkali-soluble polymer is
It is characterized in that the monomer mixture is emulsion-polymerized in the presence of a partially or completely neutralized product. In this case, the difference between the SP value of the polymer and the polymer forming the alkali-soluble polymer is 0. It is desirable that the monomer be 5 or less.

When a monomer having a SP value difference of more than 0.5 of a homopolymer is used, the balance of compatibility is lost, and the transparency and gloss of the polymer coating layer when dried are reduced. I do.

The glass transition temperature of the finally obtained aqueous polymer 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 paper is stacked. Further, when the glass transition temperature exceeds 50 ° C., the film forming property of the coating layer is reduced, so that cracks are generated, and the smoothness and glossiness of the surface are likely to be reduced.

The process for producing an aqueous polymer dispersion of the present invention is characterized in that the alkali-soluble oligomer constituting the aqueous dispersion is neutralized, and then the monomer mixture is emulsion-polymerized in the presence of the neutralized product. Is what you do.

The emulsion polymerization of the monomer mixture in the presence of the neutralized product of the alkali-soluble oligomer may be carried out by adding the monomer mixture to an aqueous medium containing the neutralized product, or by polymerizing the monomer mixture. After mixing the neutralized product and the monomer mixture to form an emulsion, the mixture is added to an aqueous medium or an aqueous medium containing the neutralized product, and polymerized. The polymerization temperature is usually from 0 to 100.
° C, preferably 30 to 90 ° C.

In the emulsion polymerization of the monomer mixture in the presence of the neutralized product of the alkali-soluble oligomer, the emulsion is usually added to the monomer mixture in an amount of 0.0
Less than 5% by weight, preferably less than 0.02% by weight of surfactant can be used. If the amount of surfactant is 0.0
If the amount is more than 5% by weight, the foaming property of the aqueous polymer dispersion is undesirably reduced.

After the emulsion polymerization, if necessary, a polymerization terminator, a polymerization inhibitor, a pH adjuster, and the like can be added.

Further, an electrophotographic transfer paper using the aqueous polymer dispersion of the present invention will be specifically described below.

In the process of studying the gloss of white paper after coating with various aqueous coating liquids for the purpose of improving the surface smoothness and gloss, the present inventors have found that the smoothness of the base paper is important.
It has been found that there is a good correlation between the center surface average roughness (SRa) and the film thickness unevenness index (Rpy), which are the indexes, and the glossiness of the white paper after the application of the aqueous polymer dispersion. Was.

As a result, the center plane average roughness (S
Ra) is 1.5 μm or less, and the film thickness unevenness index (R
py) is 250 mV or less, and the aqueous polymer dispersion of the present invention is 5.0 to 20 g / m ^{2 in} absolute dry solids.
When coated, the glossiness of the coated paper becomes 75% or more. As a result, the white paper gloss of the image part and the non-image part after printing using CLC or CLBP is the same level as the glossy photographic paper. And found that the transfer paper for electrophotography of the present invention was obtained.

The mean center surface roughness (SRa) of the base paper in the present invention means that the surface of the base paper on which the aqueous polymer dispersion is coated is a material having a cutoff value of 0.8 mm. It is a center plane average roughness in the papermaking direction measured using a needle type three-dimensional surface roughness meter, and is defined by the following mathematical formula 3. SRa is 1.5μ
m. More preferred ranges are:
The range is 45 μm or less, and more preferably 1.4 μm or less. When SRa exceeds 1.5 μm, an electrophotographic transfer paper from which a printed matter having a gloss close to that of a photographic paper having a glossy surface cannot be obtained.

[0050]

(Equation 1)

In Equation 3, Wx represents the length of the sample surface area in the X-axis direction (papermaking direction), Wy represents the length of the sample surface area in the Y-axis direction (direction perpendicular to the papermaking direction), and Sa Represents the area of the sample surface area.

Specifically, as a stylus type three-dimensional surface roughness meter and a three-dimensional roughness analysis device, S-produced by Kosaka Laboratory Co., Ltd.
Using an E-3AK type machine and a SPA-11 type machine, it can be obtained under the conditions of a cutoff value of 0.8 mm, Wx = 20 mm, Wy = 8 mm, and Sa = 160 mm ² . In the data processing in the X-axis direction, sampling is performed at 500 points, and in the scanning in the Y-axis direction, 17 lines or more are performed.

The film thickness non-uniformity index (Rpy) as used in the present invention is a film thickness for measuring a change in thickness of a sample as an electric signal through an electronic micrometer by moving a sample between two spherical styluses. Using a measuring instrument, adjust the zero point under the condition that the sensitivity range of the electronic micrometer is ± 15 μm / ± 3 V, and then scan the sample in the papermaking direction at a constant speed of 1.5 m / min to obtain the thickness of the sample in the papermaking direction. Measure the variation,
The obtained measurement signal value is calculated using an FFT analyzer.
A fast Fourier transform is performed using a Hanning window as a time window, a power spectrum (unit: mV ² ) is obtained by averaging 128 times of integration, and power values in a frequency range of ² to 25 Hz are summed up to 2/3. Is a value (unit: mV) obtained by raising the value multiplied by １ ／ to the power of １ ／. Rpy
Exceeds 250 mV, no transfer paper for electrophotography can be obtained from which a printed matter having a gloss close to that of a photographic paper having a glossy surface can be obtained.

The center plane average roughness (SRa) of the base paper is 1.5
μm or less, and the film thickness unevenness index (Rpy) is 250
Only when a base paper having mV or less is used, an electrophotographic transfer paper having not only high gloss but also high specularity can be obtained. Specularity is a quality that is emphasized on the painted surface of the car body surface, for example, and the surrounding scenery that is reflected can be seen as clearly as a mirrored scenery, extremely small and shallow Means a property that does not cause distortion or flicker caused by.

The pulp used in the base paper of the present invention includes:
Recovered paper pulp is preferably used. Recovered paper pulp is advantageous for the purpose of improving smoothness because the fiber is given an appropriate degree of flexibility during regeneration processing 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 of various strengths are accompanied, so that the handling properties of the obtained electrophotographic transfer paper, and the suitability for paper passing in CLC or CLBP. Usually, the preferable range is 30 to 50% by weight of the total pulp amount.

The raw materials of the used paper pulp referred to in the present invention include, for example, top white, ruled white, cream white, card, and the like shown in the used paper standard quality standard table of the Used 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, and OA waste paper such as PPC paper, coated paper such as art paper, coated paper, lightly coated paper, matte paper, or fine paper, color fine, notebook,
Used paper such as stationery, wrapping paper, fancy paper, medium paper, newsprint, paper change, super-hanging paper, imitation paper, pure white roll paper, uncoated paper such as milk carton, etc.
Chemical pulp paper, high-yield pulp-containing paper and the like are used, but are not particularly limited regardless of printing, copying, printing, and non-printing.

As the base paper in the present invention, either uncoated paper or coated paper can be used. The base paper having a center plane average roughness (SRa) of 1.5 μm or less and a film thickness unevenness index (Rpy) of 250 mV or less is specifically prepared by using the following method, preferably by the following method. Are obtained by combining two or more of

(1) As the natural pulp used for the base paper, sulfite pulp which is easy to produce smoothness, preferably hardwood sulfite pulp is often used. In particular,
The hardwood sulfite pulp described in or exemplified in JP-A-60-67940 is used in an amount of 30% by weight or more.

(2) A tension press is used during the drying of the wet paper. Specifically, for example, a multi-stage tension press as described in JP-A-3-29945 or exemplified herein is performed on wet paper.

(3) After making the base paper, machine calendar
At least two or more series of calendar processes are performed on the base paper using a super calendar, a thermal calendar, or the like. Specifically, for example, machine calendering and / or thermal machine calendering were performed on the base paper as the first series of calendering, and then machine calendering was further performed as necessary as the second series of calendering thereafter. Thereafter, a thermal soft calendering process described in or exemplified in JP-A-4-110939 is performed.

As the pulp that can be used in producing the base paper of the electrophotographic transfer paper of the present invention, one of natural pulp, synthetic pulp and the like, in addition to the above-mentioned hardwood sulphite pulp and waste paper pulp, or Two or more kinds can be used in combination. As the natural pulp, any pulp usually used for papermaking can be used.
That is, softwood kraft pulp, hardwood kraft pulp,
Bleached chemical pulp such as softwood sulfite pulp
Both can be used. Further, mechanical pulp having high whiteness may be used. Further, non-wood pulp produced from grass fibers such as straw, esparto, bagasse and kenaf, bast fibers such as hemp, mulberry, ganpi and 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.

Pulp is used in order to improve paper making properties and various paper properties such as strength, smoothness and uniformity of formation.
Beated by a beating machine such as a double disc refiner. The degree of beating can be selected according to the purpose in the range of 250 to 400 ml in Canadian Standard Freeness.

The beaten pulp slurry is made by a paper machine such as a fourdrinier paper machine or a round net paper machine. At this time, in the present invention, a dispersing aid for the pulp slurry usually used for papermaking, Various additives such as a paper strength enhancer, a wet paper strength enhancer, a filler, a sizing agent, a fixing agent, and a fungicide can all be added as needed. further,
If necessary, a pH adjuster, a dye, a colored pigment, a fluorescent whitening agent and the like can be added.

The dispersing aids include, for example, polyethylene oxide, polyacrylamide, smelt, and the like. The paper-strength enhancers include, for example, vegetable gum, starch,
Anionic paper strength agents such as carboxy-modified polyvinyl alcohol, cationic starch, cationic polyacrylamide, cationic paper strength agents such as polyamide polyamine epichlorohydrin resin, as a filler, for example, clay, kaolin, calcium carbonate, Examples of the sizing agent include barium sulfate, titanium oxide, aluminum hydroxide, and magnesium hydroxide. Examples of the sizing agent include higher fatty acid salts, rosin, rosin derivatives such as maleated rosin, dialkyl ketene dimer, alkenyl or alkyl succinate, and epoxidation. Examples of the fixing agent include fatty acid amides and polysaccharide esters, and examples of the fixing agent include polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationized starch, and cationic polymers such as polyamide polyamine epichlorohydrin resin. The pH adjusting agents, hydrochloric acid, sodium hydroxide, sodium carbonate and the like are used.

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

The water-soluble polymer additives include, for example, 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. Among these coating devices, it is desirable to use a system in which the inside of the paper layer is impregnated with the above-mentioned size press liquid.

The basis weight range of the electrophotographic transfer paper of the present invention is 6
0-200 g / m < ² > is preferable. When the basis weight is less than 60 g / m ^2, the smoothness specified by the present invention cannot be obtained. Also,
When the basis weight is more than 200 g / m ² , there is a problem in the suitability of CLC and CLBP for paper passing.

In the present invention, a soap-free type aqueous polymer dispersion as described above is used. In general, a low molecular weight emulsifier is used as an emulsion stabilizer in the production of an aqueous polymer dispersion. The flow characteristics of aqueous polymer dispersions stabilized with general low-molecular-weight emulsifiers show structural viscosity, are not sufficiently stable in miscibility with various solvents and resins, and are not suitable for applications such as coating and printing. The range of use is limited. In the present invention, since the smoothness of the coated surface is largely controlled by the fluidity of the aqueous polymer dispersion itself and the surface quality of the base paper, it is possible to use an aqueous polymer dispersion having no structural viscosity. preferable.

When the aqueous polymer dispersion is dried,
The emulsifier tends to inhibit the film formation of the polymer particles in the aqueous polymer dispersion, or the released emulsifier migrates to the surface after the film formation, and tends to reduce the adhesion and adhesion to various materials. In the electrophotographic transfer paper of the present invention, by developing and using a new aqueous polymer dispersion, the affinity between the surface of the electrophotographic transfer paper and the toner, as well as the adhesiveness, are improved. It is now possible to obtain the quality.

Further, in the production of the aqueous polymer dispersion, emulsion polymerization is carried out by using an oligomer-type acrylic alkali water-soluble resin in place of the emulsifier, so that the polymer particles and the Tg of each resin of the oligomer are included. By defining various physical properties within the scope of the present invention, we succeeded in developing an aqueous polymer dispersion having excellent film formability and extremely high surface gloss after coating and drying. It has become possible to obtain the electrophotographic transfer paper of the present invention which can be used in place of paper.

The coating amount of the aqueous polymer dispersion is from 5.0 to 2
0 g / m ² (dry solids) is a preferred range. When the coating amount is less than 5.0 g / m ² , the base paper is incompletely coated, and a sufficient gloss value cannot be obtained. On the other hand, the gloss value obtained even when the coating amount is 20 g / m ² or more is saturated, which is not economically preferable, and the thickness of the coating layer becomes excessively large, so that the curl of the product tends to increase. The stickiness of the coated surface also tends to increase.

The electrophotographic transfer paper of the present invention can be obtained basically by applying a coating liquid comprising the aqueous polymer dispersion of the present invention described above. However, the preferable properties improved by the present invention are deteriorated. To the extent not to be done, pigments, dyes widely used in the paper industry, toning agents such as trend brighteners, antistatic agents, surfaces including cationic resins,
It is also possible to add an appropriate combination of a water resistance improving agent for the image area. The specific example is as described above.

Examples of the apparatus for coating the aqueous polymer dispersion of the present invention on a base paper include a gate roll coater,
Alternatively, a coating apparatus such as a film transfer coater and a rod coater, an air knife coater, a blade coater, a bill blade coater, a short dwell coater, a curtain coater, or the like can be used. Among these coating devices, it is desirable to use a system in which the penetration into the 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 glossiness of the electrophotographic transfer paper after coating the aqueous polymer dispersion of the present invention is JIS P-814.
It is required to be 75% or more in the “test method for 75-degree specular glossiness of paper and paperboard” specified in 2. When the blank gloss value is less than 75%, the glossiness is insufficient and cannot be used as a substitute for glossy photographic printing paper.

The transfer paper for electrophotography according to 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.

[0077]

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.

Example 1 46 parts of ethyl acrylate, 26 parts of methyl methacrylate,
28 parts of methacrylic acid, octyl thioglycolate 8.0
Part, polymerizable surfactant (polyoxyethylene alkylpropenyl ether ammonium sulfate, Aqualon HS
10, manufactured by Daiichi 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
And heated to 80 ° C., 40 parts of a 5% aqueous potassium persulfate solution was added to the reactor, and the monomer emulsion was continuously added to the reactor maintained at 80 ° C. over 2 hours to react. Was. 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. 28% aqueous ammonia 1 was added to the obtained aqueous dispersion.
9.3 parts and 43 parts of ion-exchanged water were added to obtain an aqueous alkali 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 potassium persulfate solution was added, and 100 parts of ethyl acrylate monomer was stirred while stirring. 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 an aqueous polymer dispersion having a solid content of 38%. The glass transition temperature of the aqueous polymer dispersion of Example 1 was 16 ° C., which was within the range specified by the present invention.

Examples 2 to 4 and Comparative Examples 1 to 4 Examples 2 to 4 and Comparative Examples 1 to 3 were the same as in Examples 2 to 4 and Comparative Examples 1 to 3 except that the monomer mixture was replaced with a neutralized product or a monomer mixture shown in Table 2. Example 1
An aqueous polymer dispersion was obtained in the same manner as in the above method. In Comparative Example 4, the polymerization was performed by emulsion polymerization of the monomer mixture without neutralizing the alkali-soluble polymer.

The results of these evaluations are shown in Tables 2 and 3 below. The glass transition temperature of the aqueous dispersion of Example 2 was 30 ° C., which was within the range specified by the present invention. The glass transition temperature of the aqueous polymer dispersion of Example 3 was −
The temperature was 5 ° C., which was within the range defined by the present invention.
The glass transition temperature of the aqueous polymer dispersion of Example 4 was 16 ° C.
Which was within the range defined by the present invention. The glass transition temperature of the aqueous polymer dispersion of Comparative Example 1 was 52 ° C., which was outside the range specified by the present invention. Comparative Example 2
The glass transition temperature of the aqueous polymer dispersion was -15 ° C, which was outside the range specified by the present invention. Comparative Example 3
The glass transition temperature of the aqueous polymer dispersion is 16 ° C.,
The raw materials are different from those of the present invention within the numerical values defined by the present invention. The glass transition temperature of the aqueous polymer dispersion of Comparative Example 4 is 16 ° C., which is within the range specified by the present invention, but the production method is different from that of the present invention.

[Characteristics of Aqueous Polymer Dispersion] (Amount of coagulated material)
The mixture was filtered through a 00 mesh wire mesh, and the coagulated matter remaining in the wire mesh was dried in an infrared oven to obtain a constant weight value, which was expressed as a percentage by weight based on the solid content of the aqueous polymer dispersion.

(Antifoaming property) 100 cm ^{3 of} an aqueous polymer dispersion having a solid content of 10% was placed in a 1000 cm ³ measuring cylinder.
, Then insert a 5mmφ vinyl tube until it reaches the bottom of the graduated cylinder, blow in air for 2 minutes,
The foam was foamed until the foam became 1000 cm ³ . Thereafter, the disappearance of the bubbles was visually observed. The evaluation criteria are as follows. ：: All bubbles disappeared within 5 minutes. Δ: Bubbles disappeared within 10 minutes after 5 minutes. X: Foam does not disappear even after 10 minutes.

(Water resistance) 6 was coated with an aqueous polymer dispersion having a solid content of 30% using a wire bar, left to stand at room temperature for 48 hours, and dried. Then, water was dropped on the obtained film, and 1 minute later, water was dropped. The surface of the film in the portion thus observed was visually observed. ：: transparent. Δ: Clouding occurred. ×: Completely white.

(Film-forming properties) An aqueous polymer dispersion having a solid content of 30% was applied using a wire bar of No. 6 and dried in an atmosphere at 20 ° C., and the state of the dried film was visually observed and evaluated according to the following criteria. ：: A transparent continuous film was formed. Δ: Transparent but cracked. ×: An opaque continuous film was formed. XX: whitened and no film was formed.

(Stickiness) No. 6 was coated with an aqueous polymer dispersion having a solid content of 30% using a wire bar, dried in an atmosphere of 20 ° C., and the coated surfaces were overlaid and a load of 10 g / cm ³ was applied. A peel test was performed. The stickiness of the film was observed and evaluated according to the following criteria. ：: Peelable without resistance. Δ: There is some resistance, but there is no scratch on the peeled surface. ×: The coating adheres and is difficult to peel

[0087]

[Table 2]

[0088]

[Table 3]

Next, the above Examples 1-4 and Comparative Example 1
The following Examples and Comparative Examples are shown for electrophotographic transfer papers using the aqueous polymer dispersions of Nos. 1 to 4.

First, an example of manufacturing a base paper will be described below. <Production Example 1> A mixed pulp composed of 70% hardwood bleached kraft pulp and 30% hardwood bleached sulphite pulp was beaten using a double disc refiner to a freeness of 350 ml with Canadian Standard Freeness. Then, based on 100 parts of pulp, 3 parts of cationized starch, 0.2 part of anionized polyacrylamide,
0.4 part of an alkyl ketene dimer emulsion (as ketene dimer), 0.4 part of a polyamide polyamine epichlorohydrin resin and an appropriate amount of a fluorescent whitening agent, a blue dye,
A stock slurry was prepared by adding a red dye.

Using the stock slurry obtained as described above,
Place on a fourdrinier running at 0 m / min, form a paper web while giving appropriate turbulence, and adjust the linear pressure in the wet part in the range of 15 to 100 kg / cm in a three-stage wet press. After that, the mixture was treated with a smoothing roll, and in a subsequent drying part, a two-stage tension press in which the linear pressure was adjusted in a range of 30 to 70 kg / cm was performed, followed by drying.

Further, during the drying, 4 parts of polyvinyl alcohol, 0.05 parts of a fluorescent whitening agent, and 0.002 of a blue dye
, A size press solution consisting of 4 parts of sodium chloride and 92 parts of water, is size-pressed, and dried so that the finally obtained base paper has a moisture content of 8% with absolutely dry water.
cm and machine calendering, the basis weight is 170 g /
An electrophotographic transfer paper base paper 1 having an m ² of ² was produced. The center surface average roughness SRa of the base paper 1 was 1.35 μm, and the film thickness unevenness index Rpy was 155 mV, both of which were within the numerical values defined by the present invention.

[0093] <Production Example 2> and a basis weight in the same manner as in the production of the base paper 1, except for changing 80 g / m ^2, the basis weight was produced a base sheet 2 transfer paper for electrophotography is a 80 g / m ² . SR of base paper 2
a was 1.40 μm, and Rpy was 180 mV, both of which were within the range defined by the present invention.

<Production Example 3> The basis weight was 170 g / m ^{2 in the same} manner as in the production of the base paper 1 except that the mixing ratio of pulp was changed to 80% of hardwood bleached kraft pulp and 20% of hardwood bleached sulphite pulp. Was manufactured as a base paper 3 of transfer paper for electrophotography. The SRa of the base paper 3 is 1.56 μm, Rpy
Was 200 mV, and SRa was out of the range defined by the present invention.

<Production Example 4> A base paper for an electrophotographic transfer paper having a basis weight of 170 g / m ² in the same manner as in the production of the base paper 1 except that the blending of the pulp was changed to 100% of hardwood bleached kraft pulp. 4 was produced. SRa of base paper 4 is 2.31μ
m and Rpy were 280 mV, both of which were out of the range defined by the present invention.

<Production Example 5> A basis weight of 170 g / g was prepared in the same manner as in the production of the base paper 1 except that the blending of the pulp was changed to 70% of hardwood bleached kraft pulp and 30% of waste paper pulp.
An electrophotographic transfer paper base paper 5 having an m ² of ² was produced. The SRa of the base paper 5 was 1.31 μm, and the Rpy was 150 mV, both of which were within the range specified by the present invention.

Example 5 A base paper 1 was coated with the aqueous polymer dispersion of Example 1 at a coating weight of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Example 6 A base paper 1 was coated with the aqueous polymer dispersion of Example 1 at a coating amount of 5 g /
coating so that the m ^2, followed by drying to produce a transfer paper for electrophotography.

Example 7 A base paper 2 was coated with the aqueous polymer dispersion of Example 1 at a coating weight of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Example 8 A 10 g amount of the aqueous polymer dispersion of Example 2 was applied to a base paper 1.
/ M ² and dried to produce an electrophotographic transfer paper.

Example 9 The base polymer 1 was coated with the aqueous polymer dispersion of Example 1 at a coating weight of 20 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Example 10 A base paper 5 was coated with the aqueous polymer dispersion of Example 1 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Example 11 A 10 g amount of the aqueous polymer dispersion of Example 4 was applied to a base paper 1.
/ M ² and dried to produce an electrophotographic transfer paper.

Comparative Example 5 The base polymer 3 was coated with the aqueous polymer dispersion of Example 1 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Comparative Example 6 A base paper 4 was coated with the aqueous polymer dispersion of Example 1 at a coating amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

[0106]

Comparative Example 7 The base polymer 1 was coated with the aqueous polymer dispersion of Comparative Example 1 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Comparative Example 8 The base polymer 1 was coated with the aqueous polymer dispersion of Comparative Example 2 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper.

Comparative Example 9 The base polymer 1 was coated with the aqueous polymer dispersion of Comparative Example 3 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper. Fine cracks were observed on the coated surface of the electrophotographic transfer paper.

Comparative Example 10 The base polymer 1 was coated with the aqueous polymer dispersion of Comparative Example 4 in an amount of 10 g.
/ M ² and dried to produce an electrophotographic transfer paper. Fine cracks were observed on the coated surface of the electrophotographic transfer paper.

Examples 5 to 11 and Comparative Examples 5-1
The transfer paper for electrophotography prepared in No. 0 was evaluated by the following test method. The results of the evaluation are shown in Table 4 below. The unit is
SRa: μm, Rpy: mV, Tg: ° C., coating amount: g /
m ² , before blank gloss printing:%, blank gloss remaining ratio:%. Further, (1) to (5) in the base paper type column represent base papers 1 to 5. (1) to (8) in the polymer type column represent the aqueous polymer dispersions of Examples 1 to 4 and Comparative Examples 1 to 4.

(Blank gloss) The blank gloss was determined by measuring a sample of 20
After conditioning for 24 hours in an environment of 65 ° C and 65% RH, JIS P
The 75 degree specular gloss was measured according to -8142. In the present invention, it is desirable that the glossiness of blank paper is 75% or more. The measurement was performed both before and after printing.

(White Paper Gloss Remaining Ratio) The blank paper gloss remaining ratio was obtained by measuring a sample whose blank paper gloss was measured by FUJI Xerox: A-
Using a Color 935 machine, in a thick paper mode, using a TEST CHARTTYPE1 of the Printing Society, printing was performed by passing a blank paper sample of A4 size portrait, and the blank gloss of the blank portion after printing was measured before printing. It was determined by dividing by blank gloss. In the present invention, it is desirable that the glossiness remaining ratio of blank paper is 90% or more.

(Toner Fixing Property)
I Xerox: A-Color935 machine, in cardboard mode, TEST CHART TYPE of the Printing Society
Using a sample printed by passing a white paper sample of A4 size lengthwise using E1, a Nichiban cellophane adhesive tape “Cellotape No. 405” manufactured by Nichiban Co., Ltd. with a width of 18 mm was applied so as to prevent unevenness 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 removed has decreased. "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.

(Glossiness of Printed Section)
I Xerox: A-Color935 machine, in cardboard mode, TEST CHART TYPE of the Printing Society
Using E1, a sample printed by passing through a blank A4 size vertical paper sample was subjected to oblique light, and the glossiness was visually compared with that of a glossy surface photographic paper, and evaluated on a 4-point scale according to the following criteria. “◎”: No problem at all. "〇": Available for practical use. "△": There is a practical problem. “×”: Unavailable.

(Stackiness) The stickiness of a blank paper sample is as follows.
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. “×”: Unavailable.

[0116]

[Table 4]

[0117]

As described above, the aqueous polymer dispersion of the present invention has excellent foam suppressing properties, and can provide a coating film having high film forming properties and excellent water resistance. Further, according to the method for producing an aqueous polymer dispersion of the present invention, the above-mentioned aqueous polymer dispersion can be produced stably without coagulation. Furthermore, the electrophotographic transfer paper using the aqueous polymer dispersion of the present invention has various properties such as high white paper gloss only when the base paper specified by the present invention and the aqueous polymer dispersion are used. In any case, as a result of the improvement in a well-balanced manner, it is possible to obtain an electrophotographic transfer paper capable of obtaining a printed matter at the same level as a glossy photographic printing paper.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hashi Matsuda 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Paper Mills Co., Ltd. (72) Inventor Shunyu Tanaka 3-4-2 Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Paper Mills Co., Ltd. (72) Inventor Toshihiro Inoue 1-2-1, Night Light, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Zeon Co., Ltd. Research and Development Center (72) Inventor Liu Sang Liu 1, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture No. 2-1 in the Zeon Corporation Research and Development Center (72) Inventor Jun Hasegawa 1-2-1 Night Light, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Zeon Corporation Research and Development Center 4J002 BG04W BG04X BG05W BG05X BG06W BG06X DE026 FD310 HA07 4J011 PA65 PA69 PA70 PA76 PB14 PB15 PB30 PC02 PC06

Claims (7)

[Claims] 1. The solubility in water at 20 ° C. is 0.5% or more, and the homopolymer has an SP value of 7 (Cal / cm ³ ).
Two or more kinds of ethylenically unsaturated carboxylic acid ester monomers 4 which are ^1/2 or more and the difference is 0.5 or less
0 to 70% by weight and ethylenically unsaturated acid monomer 5 to
In the presence of a partially or completely neutralized product of 40% by weight, and from 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable with these monomers, Ethylene unsaturated carboxylic acid having a solubility in water at 0.5 ° C. of 0.5% or more, an SP value of a homopolymer of 7 (Cal / cm ³ ) ^1/2 or more, and a difference of 0.5 or less. 70 to 100% by weight of an acid ester monomer, and 0 to 3 of an ethylenically unsaturated monomer copolymerizable therewith.
An aqueous polymer dispersion obtained by copolymerizing an unsaturated monomer mixture of 0% by weight and having a glass transition temperature of -10 to 50 ° C. 2. The aqueous polymer dispersion according to claim 1, wherein the ethylenically unsaturated carboxylic acid ester monomer is selected from the group consisting of methyl acrylate, ethyl acrylate, and methyl methacrylate. 3. The solubility in water at 20 ° C. is 0.5% or more, and the homopolymer has an SP value of 7 (Cal / cm ³ ).
Two or more kinds of ethylenically unsaturated carboxylic acid ester monomers 4 which are ^1/2 or more and the difference is 0.5 or less
0 to 70% by weight and ethylenically unsaturated acid monomer 5 to
In the presence of a partially or completely neutralized product of 40% by weight, and from 0 to 30% by weight of an ethylenically unsaturated monomer copolymerizable with these monomers, Ethylene unsaturated carboxylic acid having a solubility in water at 0.5 ° C. of 0.5% or more, an SP value of a homopolymer of 7 (Cal / cm ³ ) ^1/2 or more, and a difference of 0.5 or less. 70 to 100% by weight of an acid ester monomer, and 0 to 3 of an ethylenically unsaturated monomer copolymerizable therewith.
A method for producing an aqueous polymer dispersion, wherein the polymer has a glass transition temperature of -10 to 50 ° C obtained by copolymerizing an unsaturated monomer mixture of 0% by weight. 4. The center plane average roughness (SRa) is 1.5 μm.
The base paper having a film thickness unevenness index (Rpy) of 250 mV or less is coated with a coating liquid containing the aqueous polymer dispersion according to claim 1 or 2 below. An electrophotographic transfer paper comprising a layer. 5. The transfer paper for electrophotography according to claim 4, wherein the glossiness of white paper on the surface of the coating layer is 75% or more. 6. The coating amount of the aqueous polymer dispersion is from 5 to 20.
g / m ² (dry solid content).
Or the transfer paper for electrophotography according to 5. 7. The transfer paper for electrophotography according to claim 4, wherein the base paper contains waste paper pulp.