JP2000033772A - Recording sheet for electric solidification printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the coloring density of ink and gloss of an image by permitting an ink acceptable layer to have a plastics pigment as a principal component. SOLUTION: When a high glossy image is obtained, smoothness is important in the state of a recording sheet not being compressed. If a Bekk smoothness by JISP-8119 of the recording sheet is 250 sec or more, the image gloss of the recording sheet is in a sufficient level as an image quality. If a Bekk smoothness of JIS is not sufficient by only coating a plastics pigment, a smoothness treatment can be given suitably by a super calender or the like to the recording sheet. For such a method to obtain high image gloss, it is effective to use a carrier having a high smoothness. If a Bekk smoothness of the carrier is 200 sec or more, or cast-coated paper is used, high image gloss can be attained without a smoothing treatment by a calender. Also, high image gloss can be obtained by using jointly a plastics pigment and polyvinyl pyrrolidone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an ink layer representing an image composed of desired characters, pictures, etc. on a cylinder for forming electrodes by using ink which solidifies by electric charge. The present invention relates to a printing method for transferring a recording sheet to a recording sheet, that is, a recording sheet used in an electrocoagulation printing method.

[0002]

2. Description of the Related Art The electrocoagulation printing method is disclosed in U.S. Pat. Nos. 3,892,645, 4,555,320, 4,764,264, and JP-A-4-504688. Disclosed and characterized in that the ink used is an aqueous ink, the composition of which is composed of water, an electrolytically coagulable polymer, a soluble electrolyte and a colorant. An electrolytically coagulable polymer is, for example,
Albumin, gelatin, casein, agar, polyacrylic acid, polyacrylamide, polyvinyl alcohol, etc., and the soluble electrolyte is, for example, lithium chloride,
Sodium chloride, calcium chloride, potassium chloride, nickel chloride, copper chloride, magnesium sulfate and the like.

[0003] The basic mechanism of the electrocoagulation method is as follows. When a potential difference is generated between the electrodes while the ink layer having the above composition is sandwiched between the positive and negative electrodes, coagulation of the colloid and adhesion of the coagulated colloid to the anode occur. This coagulation is a color coagulation that occurs in a state containing the colorant in the ink, and by appropriately arranging the color coagulation colloid,
An arbitrary image can be reproduced, and the reproduced image can be recorded on a recording sheet by transferring the reproduced image to a recording sheet by any method.

The construction of a printing machine utilizing the electrocoagulation method is described in detail in the above-mentioned Japanese Patent Publication No. 4-504688, but will be briefly described with reference to FIG. FIG.
This schematically shows the configuration of a printing press that forms a color image and transfers it to a recording sheet. In the case of multicolor printing, one printing press is configured by connecting a plurality of similar devices. I do. In FIG. 1, reference numeral 1 denotes a metal cylinder serving as a positive electrode, which is made of an electrically inert metal such as stainless steel. An independent cathode, which is insulated from the anode 1, is disposed on the cylindrical box 2, and the ink ejected from the ink ejector 3 fills the space between the two electrodes.
The anode 1 rotates continuously in the clockwise direction in the drawing, and intermittently generates a potential difference between the anode 1 and the cathode 2, thereby forming a coagulated colloid portion and a non-coagulated ink portion in the ink filling between the two electrodes. The coagulated colloid adheres to the anode 1, and only the non-coagulated ink is selectively removed from the anode with a wiper indicated by reference numeral 4.

[0005] A press roll 5 is pressed against the anode 1, and a recording sheet 6 is fed between the two. Therefore, the solidified colloid part supported on the peripheral surface of the press roll 5 reaches the position of the press roll 5 with the rotation of the anode 1 and is transferred onto the recording sheet 6 in contact. At this time, the nip pressure between the press roll 5 and the anode 1 is 30 to 50 kg /
cm. The anode 1 after the transfer is further rotated to be cleaned by the cleaning device 7 while being further rotated, and then the corrosion inhibitor is applied by the corrosion inhibitor coating device 8 to complete one cycle.

When this printing method is compared with conventional printing methods such as offset printing, letterpress printing, screen printing, gravure printing, etc., a major difference is that the electrocoagulation printing method falls in the category of so-called "plateless printing". Is mentioned. Plateless printing has many advantages, but in the conventional printing method, a step of raising the plate is indispensable, and the ratio of platemaking cost to the cost per printed sheet is extremely large. Does not require a plate making process, so there is no plate making cost, and in the case of conventional "printing with plate", it is fast while printing the same printed matter,
While it takes time to prepare for changing to a different printing unit (exchanging a plate), “plateless printing” is a method of reading and sending data sent from a computer each time, so different printed materials are printed. Preparation time is extremely short. As a result, it can be said that the electrocoagulation printing method is an overwhelmingly advantageous printing method as compared with the conventional method, especially in the printing of small lots.

[0007] Further, it is impossible with a conventional printing method that, for example, a common body of direct mail is printed at the same time as printing different addresses, while hardly any preparation time is required for printing different printed materials. To the so-called page variable.

Further, a printing machine using the electrocoagulation method is a printing machine constituted by a relatively simple combination of sturdy components, and can easily cope with high speed. Printing speed is
The upper limit is determined by the information transmission speed from the computer rather than the printing press itself. Even at the current computer level, a speed of several hundred m / min is a sufficiently high figure, and is considerably faster than other "plateless printing" such as an ink jet method which has been rapidly progressing in recent years, and the productivity is high. high.

As the colorant used in the electrocoagulation method, the same colorant as that used in the ink of the conventional printing method can be used. The shape and size of the aggregated colloid are the shape of the cathode (tip of the wire). And the size is almost the same, and the dot gain on the recording sheet cannot be considered. Therefore, clear image reproduction by fine and sharp dots is possible.

As described above, the electrocoagulation printing method is an excellent printing method which has high productivity and high image quality comparable to the conventional printing method, and also supports small lots and page variable properties which cannot be achieved by the conventional method. It can be said that there is.

The present inventors have proposed a recording sheet suitable for the above-described electrocoagulation printing in Japanese Patent Application No. Hei 8-319038.
In particular, the characteristics required for a recording sheet for electrocoagulation printing of a monochrome fine image include a wetting time of 15 milliseconds or less and an absorption coefficient of 5 ml / m obtained from an absorption curve of pure water by a dynamic scanning liquid absorption system. it is ² s ^-1/2 or more, whereas, characteristics required for the electrocoagulation printing recording sheet of full-color, measured at light wavelength 0.5μm pressured at the positive reflection type smoothness meter 40 kg / cm @ 2 40% contact rate
Above, the wetting time determined from the absorption curve of pure water by a dynamic scanning absorptiometer is 15 milliseconds or less, and the absorption coefficient is 10 m
It is disclosed that the ratio is 1 / m2s-1 / 2 or more. Furthermore, in order to satisfy this physical property, it is disclosed that a structure containing at least one selected from the group consisting of synthetic amorphous silica, silica sol, colloidal silica, alumina sol, colloidal alumina, boehmite, and pseudo-boehmite is important. It is. Although this proposal includes a coating type, the filler in the coating layer was limited to the inorganic filler as described above.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording sheet for electrocoagulation printing of the type in which a plastic pigment excellent in ink color density and image gloss is applied.

[0013]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a recording sheet having an ink receiving layer containing a plastic pigment as a main component is excellent in the color development of an ink. It has been found that a recording sheet having an ink receiving layer containing as a main component is particularly excellent in ink color development and image gloss of an image, and a recording sheet having high Beck smoothness is excellent in image gloss, and has completed the present invention. .

That is, the recording sheet for electrocoagulation printing of the present invention is characterized in that, in the recording sheet for electrocoagulation printing in which an ink receiving layer is provided on a support, the ink receiving layer mainly comprises a plastic pigment. It is assumed that.

According to the present invention, a printing paper suitable for reproducing an image having a high color density and a high gloss can be obtained.
It can be effectively used for various printed materials such as newspapers, magazines, posters, business form papers, postcards, and various publications.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Plastic pigments usable in the present invention are known per se, and are generally referred to as organic pigments, organic pigments and organic fillers and generally do not form a self-film. However, it also includes a so-called binder pigment having some self-film-forming properties. Further, those having a hollow structure, a crosslinked structure, and a core-shell structure are also included. These are synthetic polymer particles having a particle size of 5 μm.
Hereinafter, particularly fine particles having a size of 0.05 μm to 2 μm, such as styrene-acrylic, (meth) acrylic acid (ester) -based, styrene-butadiene-based, and polystyrene-based
Urea-formaldehyde and the like can be mentioned, and these can be used alone or in combination of two or more. These are generally commercially available.

By using the plastic pigment in the present invention, the transfer rate of the ink composed of the coagulated colloid is improved, and a high ink color density can be obtained.

The plastic pigment used in the present invention is preferably non-film-forming. For this purpose, the glass transition temperature and the minimum film forming temperature of the plastic pigment are preferably high, and styrene-acrylic, (meth)
Acrylic acid (ester) type, styrene-butadiene type,
It is preferably a hollow structure or a crosslinked structure. If a plastic pigment having a strong film-forming property is used, the void structure is reduced or the void is extremely reduced, so that the transfer rate of the ink-coagulated colloid to the recording sheet is deteriorated.

In the present invention, an aqueous adhesive can be used to fix the plastic pigment to the support. For example, oxidized starch, etherified starch,
Carboxymethyl cellulose, hydroxyethyl cellulose, other cellulose derivatives, casein, gelatin, soy protein, polyvinyl alcohol and its derivatives, maleic anhydride resin, ordinary latex, ordinary styrene-butadiene copolymer, methyl methacrylate-
Condensed diene polymer latex such as butadiene copolymer, acrylic polymer latex such as acrylate or methacrylate polymer or copolymer, ethylene vinyl acetate copolymer, melamine resin, urea resin, etc. An aqueous adhesive such as a cured synthetic resin, a synthetic resin adhesive such as a polyurethane resin, an unsaturated polyester resin, a vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, or an alkyd resin is used alone or in combination. These adhesives are available in plastic pigment 100
0 to 100 parts by weight, preferably 3 to 30 parts by weight based on parts by weight
Although parts by weight are used, the ratio is not particularly limited as long as it is sufficient for binding the plastic pigments and fixing them to the support. However, if the adhesive is used in an amount of 100 parts by weight or more, it is not preferable because the gap structure is reduced or the gap is extremely reduced due to the film forming action of the adhesive.

In the present invention, the wetting time and the absorption coefficient obtained from a pure water absorption curve by a dynamic scanning absorptiometer are important factors. If the wetting time exceeds 15 milliseconds, the transfer rate of the coagulated colloid to the recording sheet is low because the transfer of water from the coagulated colloid to the recording sheet does not occur within the time that the coagulated colloid is in contact with the recording sheet. If the absorption coefficient is less than 5 ml / m ² s ^-1/2 , the absorptivity of the coagulated colloid to the recording sheet is poor.

If the plastic pigment is provided on a support, the wetting time is 15 milliseconds or less and the absorption coefficient is 5 m.
1 / m ² s ^-1/2 or more. However, even if these conditions are satisfied, if the contact area ratio between the coagulated colloid and the recording sheet when nipped between the anode and the press roll is small, uneven transfer of water from the coagulated colloid to the recording sheet occurs, and the transfer rate is low. Become. However, at the time of the nip, 30-50k
A pressure of g / cm 2 is applied, and it cannot be said that there is always a correlation between the smoothness when no pressure is applied and the transfer rate of the coagulated colloid.

The present inventors have found that there is a high correlation between the contact rate and the transfer rate of coagulated colloid when measured with a light having a wavelength of 0.5 μm under a pressure of 40 kg / cm 2 using a specular reflection type smoothness meter. It was found that when the wetting time was 15 ms or less and the absorption coefficient was 5 ml / m ² s ^-1/2 or more, the transfer rate of the coagulated colloid was high when the contact rate was 30% or more. .

On the other hand, the gloss of an image after printing is also one of the important factors that determine the image quality, but it has been found that the smoothness of the recording sheet is important in obtaining a high gloss image.

The smoothness in this case is the smoothness in a state where no pressure is applied. JIS P-811 for recording sheets
If the Beck smoothness according to No. 9 is 250 seconds or more, the image gloss on the recording sheet is at a level that can sufficiently satisfy the image quality. If the Beck smoothness is less than the above just by applying the plastic pigment, the recording sheet may be subjected to a smoothing process using a super calender or the like.

As a method for obtaining high image gloss, it is effective to use a support having high smoothness. When the support has a Bekk smoothness of 200 seconds or more, or when a cast coated paper is used, high image gloss can be obtained without a smoothing treatment using a calendar. On the other hand, the use of a calendered support can increase the image gloss.

It has also been found that the combined use of a plastic pigment and polyvinylpyrrolidone is effective as a method for obtaining high image gloss. Polyvinyl pyrrolidone is used in an amount of 0.1 parts by weight based on 100 parts by weight of the plastic pigment.
It is preferable to use 5 to 200 parts by weight. If the amount of polyvinylpyrrolidone is less than 0.5 part by weight, the effect is not recognized. When the amount of polyvinylpyrrolidone exceeds 200 parts by weight, the drying property of the ink is deteriorated.

In the present invention, known polyvinylpyrrolidone can be used.

As the support of the present invention, a film having high smoothness, synthetic paper, high-quality paper or coated paper, paper having high cushioning properties, and nonwoven fabric are suitable.

The paper used for the support of the present invention refers to a raw material obtained by mixing wood fibers and non-wood fibers, fillers and various chemicals, which have been appropriately beaten with a known beater, with water. It is a sheet-like material made using a known paper machine such as a net paper machine, an inclined paper machine, or a twin wire paper machine.

The film is formed by adding an organic resin such as viscose, acetate, polyethylene, polypropylene, polyvinyl chloride, polystyrene, nylon, polyacetal, polycarbonate, polyethylene terephthalate, and, if necessary, other fillers and chemicals. In addition, it is a sheet-like material thinned by a known method such as a melt extrusion method, a calendar method, a stretching method, and a melt casting method, and so-called synthetic paper also falls into this category.

Further, the nonwoven fabric is a fiber made of wood fiber, cotton, rayon, polyethylene terephthalate, acrylic, acetate, nylon, polypropylene or the like as a raw material, and is subjected to a spunbond method, a papermaking method, a dry method using a card machine or a garnet machine. It is formed into a sheet by a known method such as, for example.

These supports may consist of a single layer, or may have a structure like a so-called coated paper in which a coating layer comprising a known filler and a binder is provided on the sheet surface. When a cast coated paper is used, a paper manufactured by a known method can be used.

In the present invention, a known coating apparatus such as a blade coater, a roll coater, an air knife coater, a rod coater, and a wire bar coater can be used as a means for providing a coating layer on a support.

In the ink receiving layer, additives generally used for coating such as an antifoaming agent, a defoaming agent, a thickener, a preservative, and an antifungal agent are compounded within a range not to impair the performance described above. it can.

[0035]

EXAMPLES [Production of Support A] 40 parts by weight of softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (L
BKP) at a concentration of 350 ml C.I. S. Beat it to F,
10 parts by weight of clay, 0.3 part by weight of a sizing agent (trade name "Size Pine E", manufactured by Arakawa Chemical Industries, Ltd.), and 2.0 parts by weight of a sulfuric acid band were added to the mixture to prepare a paper material. A base paper having a basis weight of 105 g / m2 was obtained by a conventional method using a net paper machine. Then, 80 parts by weight of kaolin (trade name "UW-90", manufactured by Engelhard), 20 parts by weight of heavy calcium carbonate (trade name "FMT90", manufactured by Fimatec Corporation), and 80 parts by weight of water, phosphoric acid A coating prepared by adding 5 parts by weight of esterified starch (trade name "MS-4600", manufactured by Nippon Shokubai Co., Ltd.) and 13 parts by weight of styrene butadiene latex (trade name "Polylac 750", manufactured by Mitsui Chemicals, Inc.) The working liquid was applied to the base paper using an air knife coater so that the surface of the base paper became 15 g / m 2, to obtain a support A. Beck smoothness 120 seconds.

[Manufacture of Support B] The support A was subjected to a super calender treatment to a Beck smoothness of 300 seconds.
Support B was obtained.

[Production of Support C] 20 parts by weight of bleached softwood kraft pulp (NBKP) and 80 parts by weight of hardwood bleached kraft pulp (LBKP) were mixed with 350 ml of C.I. S. F, beaten with 10 parts by weight of clay, 0.3 parts by weight of a paper strength agent (trade name "Polystron 191", manufactured by Arakawa Chemical Industry Co., Ltd.), a sizing agent (trade name "Size Pine E"), Using a stock prepared by adding 0.3 parts by weight of Arakawa Chemical Industry Co., Ltd. and 2.0 parts by weight of a sulfuric acid band, a support having a basis weight of 128 g / m2 by a conventional method using a fourdrinier paper machine. C base paper was obtained. Beck smoothness 70 seconds.

[Production of Support D] 50 parts by weight of bleached softwood kraft pulp (NBKP) and 50 parts by weight of hardwood bleached kraft pulp (LBKP) were mixed with 350 ml C.I. S. F, beaten it, and added 1 part by weight of a sizing agent (trade name “Size Pine E”, manufactured by Arakawa Chemical Industry Co., Ltd.) and 1.5 parts by weight of a sulfuric acid band to prepare a fourdrinier paper using the stock. A base paper having a basis weight of 105 g / m2 was obtained by a conventional method using a machine. On the other hand, kaolin (trade name “UW-90”, manufactured by Engelhard Co.)
8.5 parts by weight, 25 parts by weight of a plastic pigment (trade name “U Pearl C-122”, manufactured by Mitsui Chemicals, Inc.)
35 parts by weight of aluminum hydroxide (trade name "Heidilite H-42", manufactured by Showa Denko KK) and 1.5 parts by weight of Satin White were dispersed by a ball mill. Subsequently, 10 parts by weight of a 15% casein solution, 15 parts by weight of a styrene butadiene latex having a solid content of 47%, and calcium stearate 1.
5 parts by weight and water were added to obtain a paint having a total solid content of 45%. Next, this paint was applied to the base paper with an air knife coater so that the solid content was 20 g / m 2, and a linear pressure of 150 g / m 2 was obtained.
The support D was obtained by a rewetting method using a zinc sulfate or calcium formate aqueous solution as a rewetting liquid by a device comprising a pressure roll having a pressure of 500 kg / cm and a diameter of 500 mm and a cast drum having a diameter of 1500 mm heated to a predetermined temperature. Beck smoothness 1000 seconds or more.

[Example 1] Plastic pigment (trade name "Movinyl 972", manufactured by Hoechst Gosei Co., Ltd., styrene-acrylic type, Tg = 105 ° C, MFT> 100
(C) 100 parts by weight, 5 parts by weight of polyvinyl alcohol (trade name "PVA117", manufactured by Kuraray Co., Ltd.) was added to prepare a coating liquid. The coating solution was applied to the support B with a wire bar coater so as to have a coating amount of 6 g / m2, and dried to obtain a recording sheet for electrocoagulation printing.

Example 2 In Example 1, the support B
Was changed to the support A in the same manner as in Example 1,
A recording sheet for electrocoagulation printing was obtained. Example 3 A recording sheet for electrocoagulation printing was obtained in the same manner as in Example 1, except that the support B was changed to the support C. Example 4 100 parts by weight of a plastic pigment (trade name “Movinyl 972”, manufactured by Hoechst Gosei Co., Ltd.) was mixed with polyvinyl alcohol (trade name “PVA117”).
A coating liquid was prepared by adding 5 parts by weight of Kuraray Co., Ltd.) and 5 parts by weight of polyvinylpyrrolidone (trade name “Rubiscol K90”, manufactured by BASF). This coating solution is applied to the support B,
Coating was performed with a wire bar coater so as to have a coating amount of 6 g / m 2, followed by drying and supercalendering to obtain a recording sheet for electrocoagulation printing.

Example 5 The recording sheet obtained in Example 1 was subjected to a super calendar treatment to obtain a recording sheet for electrocoagulation printing.

Examples 6 to 13 Recording sheets for electrocoagulation printing were obtained in the same manner as in Example 5, except that the plastic pigment was changed to those shown in Table 1.

Example 14 A recording sheet for electrocoagulation printing was obtained in the same manner as in Example 5, except that the support B was changed to the support D.

[0044]

[Table 1]

Comparative Example 1 100 parts by weight of an acrylic emulsion (trade name “Nacrylic 178-6182”, manufactured by Kanebo NS Co., Ltd., styrene-acrylic type) were mixed with polyvinyl alcohol (trade name “PVA11”).
7 ", manufactured by Kuraray Co., Ltd.) to prepare a coating solution. This coating solution was applied to the support B with a wire bar coater so as to have a coating amount of 6 g / m 2, dried, and then supercalendered to obtain a recording sheet for electrocoagulation printing.

Comparative Example 2 Polyvinyl alcohol (trade name “PVA117”, manufactured by Kuraray Co., Ltd.) was used as a support B.
Coating was performed with a wire bar coater so as to have a coating amount of 6 g / m 2, followed by drying and then supercalendering to obtain a recording sheet for electrocoagulation printing.

The above Examples 1 to 14 and Comparative Examples 1 and 2
Table 2 shows the ink color densities of black solid printed portions and the gloss of printed images performed by an electrocoagulation printing machine (manufactured by Elcorthy). In Examples 1 to 14, a dynamic scanning absorptiometer (“KM350-D” manufactured by Kyowa Seiko Co., Ltd.) was used.
1)) and a wetting time and an absorption coefficient determined from a liquid absorption curve of pure water by a specular reflection type smoothness meter (Toyo Seiki Seisakusho Co., Ltd.) at a pressure of 40 kg / cm 2 and measured with a light beam having a wavelength of 0.5 μm. Table 2 shows the contact ratio at that time and the Beck smoothness determined by JIS P-8119. The ink color density is a value measured with a color checker manufactured by Macbeth. Regarding these, the four-point evaluation of ◎, ○, △, × is also described,
◎ and ○ were made practical. The print gloss of the image is JI
The value of the 60-degree specular gloss defined in SZ-8741 was defined as the gloss. Regarding these, the four-point evaluation of ◎, △, Δ, and × is also described, and ◎ and ○ are particularly excellent in gloss.

[0048]

[Table 2]

From the results in Table 2, the following has been found.

(1) As can be seen from Comparative Examples 1 and 2, when a resin is provided in the receiving layer instead of the plastic pigment, ink transfer and color development are poor.

(2) As can be seen from Examples 1 to 5 and 8 to 11, the use of a styrene-acrylic plastic pigment resulted in an excellent ink color density.

(3) As can be seen from Example 12, when a methacrylic acid-based plastic pigment was used, the ink color density was excellent.

(4) As can be seen from Example 13, the use of a styrene-butadiene-based plastic pigment provided excellent ink color density.

(5) As can be seen from Example 4, the use of polyvinylpyrrolidone resulted in an excellent image ink gloss.

(6) As can be seen from the comparison of Examples 1, 2, 3, and 15, the higher the Beck smoothness of the recording sheet, the better the ink gloss of the image.

(7) As can be seen from Examples 10 and 11, the use of a plastic pigment having a hollow structure provided excellent ink color density and ink gloss.

(8) As can be seen from Examples 6 and 8, the use of a plastic pigment having a crosslinked structure provided excellent ink color density and ink gloss.

(9) As can be seen from Example 14, when the support is cast coated paper, the reflectance, Beck smoothness,
Excellent ink glossiness of image.

[0059]

As described above, the recording sheet of the present invention is a printing sheet suitable for reproducing a high-ink color density and high-gloss image using a printing machine utilizing an electrocoagulation printing method. , Newspapers, magazines, posters, business form papers, postcards, etc., and various printed materials and various publications.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an electrocoagulation printing machine using a recording sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Colloid ejector 4 Wiper 5 Press roll 6 Recording sheet 7 Cleaning device 8 Corrosion inhibitor application device

Claims (8)

[Claims] 1. A recording sheet for electrocoagulation printing comprising an ink-receiving layer provided on a support, wherein the ink-receiving layer comprises a plastic pigment as a main component. 2. The method according to claim 1, wherein the plastic pigment is at least one selected from the group consisting of styrene-acrylic, (meth) acrylic acid (ester) -based, and styrene-butadiene-based. 4. A recording sheet for electrocoagulation printing according to item 1. 3. The recording sheet according to claim 1, wherein the plastic pigment has a hollow structure. 4. The recording sheet for electrocoagulation printing according to claim 1, wherein the plastic pigment has a crosslinked structure. 5. The recording sheet for electrocoagulation printing according to claim 1, further comprising polyvinylpyrrolidone. 6. The ink receiving layer has a wetting time of 15 milliseconds or less and an absorption coefficient of 5 ml / m ² s ^-1/2 or more obtained from a liquid absorption curve of pure water by a dynamic scanning liquid absorption meter. Apply a pressure of 40 kg / cm2 with a reflection type smoothness meter and apply a wavelength of 0.5 μm.
Of 30% or more when measured with a light beam of JIS
The recording sheet for electrocoagulation printing according to any one of claims 1 to 5, wherein the Bekk smoothness according to P-8119 is 250 seconds or more. 7. The recording sheet for electrocoagulation printing according to claim 1, wherein the support has a Beck smoothness according to JIS P-8119 of 200 seconds or more. 8. The recording sheet for electrocoagulation printing according to claim 1, wherein the support is a cast coated paper.