JPH10171146A - Transfer paper for wet electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fixability of a toner after printing by coating the surface of transfer paper having a specified ash content with a specified amt. of a specified Zr compd. SOLUTION: The surface of transfer paper for wet electrophotography having 5-20wt.% ash content is coated with 0.05-1.00g/m<2> (expressed in terms of ZrO2 ) at least one kind of Zr compd. selected from among ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate. Such a Zr compd. is generally used as an adhesiveness improver or a crosslinking agent in an adhesive or ink. At the time when a liq. toner reaches the surface of the transfer paper coated with the Zr compd. before printing, the Zr compd. forms a complex with a polar group existing in the toner and the fixability of the toner on the surface of the paper is improved. Work efficiency after printing is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet electrophotographic transfer paper for printing by an electrophotographic method using a liquid toner. More specifically, it is a plain paper type wet electrophotographic transfer paper having good fixability of toner to paper when printing using an electrophotographic method using liquid toner.

[0002]

2. Description of the Related Art Recent trends in the printing industry include (1) high-speed offset printing, (2) high-definition printing, and (3) multi-product small-lot printing.

In particular, printing machines of various printing systems such as a dry electrophotographic system, a wet electrophotographic system, and an ink jet system have been developed in order to cope with various kinds of small lot printing. Among these printing methods, the wet electrophotographic method can make the toner particle diameter finer than the toner of the dry electrophotographic method, and can provide an image with higher sharpness compared to the dry electrophotographic method. It is possible.

Conventionally, as transfer paper for wet electrophotography, a transfer paper coated with a resin emulsion on its surface has been used. As the coating resin, a polyvinyl acetate emulsion, a vinyl acetate / butyl acrylate copolymer emulsion, a styrene / butyl acrylate copolymer emulsion, a methyl acrylate / ethyl acrylate copolymer emulsion are used. Was applied. Therefore, the paper did not have the appearance of "plain paper". Further, it has been considered that plain paper cannot be used in a wet electrophotographic printing machine due to poor transfer efficiency during printing.

[0005] However, recently, the Journal of the Society of Electrophotography, No. 3
Vol. 1 No. 1 (1992) p77-p81, "Monthly Printing Information September Issue (1995)" published by Printing & Publishing Laboratory Co., Ltd.
As introduced in 22 to 23, a wet electrophotographic printing machine capable of printing on plain paper has been developed by using liquid toner using tentacle-shaped special resin particles.
It has been used as a printing machine for “small lot printing”.

[0006]

As described above, although the improvement of the toner has made it possible to perform printing on plain paper, the fixability of the toner on plain paper is weak, and cutting / printing after printing is difficult. In the bookbinding process, the toner may be partially missing from the printing surface due to an operation such as rubbing between papers or attaching a tape to the printing surface. SUMMARY OF THE INVENTION An object of the present invention is to provide a plain paper type wet electrophotographic transfer paper having good fixability of a toner to a paper surface and excellent workability after printing.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned drawbacks, and as a result, have come to invent the following wet type electrophotographic transfer paper.

That is, the wet electrophotographic transfer paper of the present invention comprises:
A transfer paper for wet electrophotography, wherein the ash content of the paper is 5 to 20% by weight, and any one of ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate is coated on the surface of the transfer paper with Z
wherein the 0.05~1.00g / m ² was applied in and rO ₂ terms.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The transfer paper for wet electrophotography of the present invention will be described in detail below.

First, the present inventors examined the ash content of wet electrophotographic transfer paper and the fixability of liquid toner to the paper.

When printing is performed using a wet electrophotographic printing machine, the toner transferred to the paper surface immediately after printing still contains a slight amount of a dispersion medium. This dispersion medium is
By being absorbed in the paper layer, the toner is firmly fixed on the paper surface. And the ash content in the paper is 5-20% by weight.
By doing so, the dispersion medium can be efficiently absorbed from the toner on the paper surface, and it has been found that the fixability of the toner to the paper surface is improved.

If the ash content of the paper is less than 5% by weight, the amount of the dispersion medium absorbed is insufficient, and the fixation of the toner on the paper surface is weak.

On the other hand, when the ash content in the paper is more than 20% by weight, the effect of improving the fixability of the toner reaches saturation, and the strength of the paper itself is unnecessarily reduced. Then, rather than the toner itself being removed from the surface of the transfer paper, the toner falls off the surface of the transfer paper together with the filler. As a result, the fixing strength of the toner decreases.

The internal filler that can be used in the wet electrophotographic transfer paper of the present invention includes, for example, light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc,
Calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, water Examples include white inorganic pigments such as magnesium oxide, styrene-based plastic pigments, acrylic-based plastic pigments, polyethylene, microcapsules, and organic pigments such as urea resin and melamine resin.

As described above, by adjusting the ash content of the transfer paper for wet electrophotography to a certain value, the toner fixability on the transfer paper was improved, but it was not sufficient. Then, improvement of the chemical fixing power between the toner itself and the paper surface was examined next.

In general, the liquid toner used in a wet electrophotographic printing machine includes (1) a colorant, (2) a dispersion medium soluble-insoluble polymer, (3) a charge control agent, and (4) a dispersion component. Medium. The toner as a whole is in a state where polar groups and non-polar groups are mixed. The present inventors diligently studied a material that can function as an anchor agent between the liquid toner and the paper surface when the liquid toner is transferred to the paper surface by a printing machine. As a result, they have found that a zirconium compound exhibits an effect as an anchoring agent.

Some of the zirconium compounds are generally used in inks and adhesives as adhesion improving agents and crosslinking agents. By applying the zirconium compound before printing on the surface of the wet electrophotographic transfer paper, a complex is formed with the polar groups present in the liquid toner when the liquid toner comes to the paper surface, and the liquid toner paper It is believed that the fixability to the surface is improved.

More specifically, one of ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate is converted to 0.05 to 1.00 g / m _{2 in} terms of ZrO _2.
It has been found that the fixability of the toner after printing can be improved by applying ^two .

When the coating amount of the zirconium compound is less than 0.05 g / m ^{2 in} terms of ZrO ₂ , the effect of improving the toner fixing property is not sufficient.

On the other hand, when the coating amount of the zirconium compound is Zr
If O ₂ conversion often exceed 1.00 g / m ^2, the effect of improving toner fixability it reaches the saturation point. Also, when the concentration of the zirconium compound in the coating solution is high, the solution stability of the coating solution may be deteriorated.

As described above, the ash content of the wet electrophotographic transfer paper is adjusted to 5 to 20% by weight, and any one of ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate is formed on the surface of the transfer paper. 0.05 to one in terms of ZrO _2.
By applying 00 g / m ^2, it is possible to provide a transfer sheet for wet electrophotography which has good fixation of toner when printed by a wet electrophotographic printing machine and has good workability after printing.

As the support for the transfer paper for wet electrophotography of the present invention, a paper-like material such as a paper mainly composed of wood fibers or a non-woven fabric mainly composed of wood fibers or synthetic fibers can be used. Wood pulp is NBKP, LBK
In addition to P, NBSP, LBSP, GP, TMP and the like, used paper pulp is used, and used alone or in combination as needed.

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, and paperboard,
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 internal sizing agent for the transfer paper for wet electrophotography of the present invention, a sizing agent used in acidic papermaking and neutral papermaking such as rosin sizing agent, alkyl ketene dimer, alkenyl succinic anhydride and the like are used. can do.

On the surface of the wet electrophotographic transfer paper of the present invention, a binder such as starch and polyvinyl alcohol, a styrene-acrylic or styrene-maleic acid-based surface sizing agent, and a dimensional stabilizer such as ethylene-urea resin are used. Of course, inorganic conductive agents such as sodium chloride and potassium chloride, organic conductive agents, surfactants, pigments and dyes can be applied.

As a device for applying the surface size liquid by a size press, 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.

In the papermaking method of the present invention, a paper machine known in the papermaking industry, such as a fourdrinier paper machine, a twin wire paper machine, a combination paper machine, a round mesh paper machine, a Yankee paper machine, can be used as appropriate.

Other additives include, for example, a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust inhibitor.

The wet electrophotographic transfer paper according to the present invention comprises:
The transfer sheet for wet electrophotography according to the present invention is used as a recording sheet for heating and fixing toner widely used not only as a transfer sheet for wet electrophotography but also widely used in copiers and printers of a dry electrophotography system. You can also.

[0030]

The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples. Further, “parts” and “%” shown in Examples are
Unless indicated otherwise, parts by weight and% by weight are indicated.

First, base papers having different ash contents, "base paper 1" to "base paper 6", were prepared in the following manner in order to prepare transfer papers for wet electrophotography having different ash contents.

Preparation of "Base Paper 1" First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness: 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo; Tamapearl 121) 5 parts Sulfuric acid band 0.8 parts Cationized starch (National Starch; Cato3210) 1 part Alkenyl anhydrous succinic Acid (manufactured by Arakawa Chemical Co .; Seisbain K-903) 0.15 parts Yield improver (manufactured by Himo; NR11LS) 0.02 part

A base paper having a basis weight of 100 g / m ² and an ash content of 3.0% was prepared from a 0.5% by weight pulp slurry having the above composition using a fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 1”.

Preparation of "Base Paper 2" First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness; 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo; Tamapearl 121) 7 parts Sulfuric acid band 0.8 parts Cationized starch (National Starch; Cato3210) 1 part Alkenyl anhydrous succinic Acid (manufactured by Arakawa Chemical Co .; Seisbain K-903) 0.15 parts Yield improver (manufactured by Himo; NR11LS) 0.02 part

A base paper having a basis weight of 100 g / m ² and an ash content of 5.0% was prepared from a 0.5% by weight pulp slurry having the above composition using a Fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 2”.

Preparation of "base paper 3"; First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness: 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo; Tamapearl 121) 15 parts Sulfuric acid band 0.8 parts Cationized starch (National Starch; Cato3210) 1 part Alkenyl anhydrous succinic Acid (manufactured by Arakawa Chemical Co .; Seisbain K-903) 0.15 parts Yield improver (manufactured by Himo; NR11LS) 0.02 part

A 0.5% by weight pulp slurry having the above composition was made into a base paper having a basis weight of 100 g / m ² and an ash content of 10.0% by using a fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 3”.

Preparation of "Base Paper 4" First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness: 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo Co., Ltd .; Tamapearl 121) 25 parts Sulfuric acid band 0.8 parts Cationized starch (National Starch Co., Ltd .; Cato3210) 1 part Alkenyl anhydride soak Acid (manufactured by Arakawa Chemical Co .; Seisbain K-903) 0.15 parts Yield improver (manufactured by Himo; NR11LS) 0.02 part

A base paper having a basis weight of 100 g / m ² and an ash content of 15.0% was prepared from a 0.5% by weight pulp slurry having the above composition using a Fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 4”.

Preparation of "Base Paper 5"; First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness: 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo; Tamapearl 121) 30 parts Sulfuric acid band 0.8 part Cationized starch (National Starch; Cato3210) 1 part Alkenyl anhydrous succinic Acid (manufactured by Arakawa Chemical Co., Ltd .; Seisbain K-903) 0.15 part Yield improver (manufactured by Hymo Corporation; NR11LS) 0.03 part

A base paper having a basis weight of 100 g / m ² and an ash content of 20.0% was prepared from a 0.5% by weight pulp slurry having the above composition by using a fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 5”.

Preparation of "Base Paper 6" First, a pulp slurry was prepared according to the following base paper composition. <Base paper composition> LBKP (freeness: 400 ml) 100 parts Light calcium carbonate (Okutama Kogyo; Tamapearl 121) 37 parts Sulfuric acid band 0.8 part Cationized starch (National Starch; Cato3210) 1 part Alkenyl anhydrous succinic Acid (manufactured by Arakawa Chemical Co., Ltd .; Seisbain K-903) 0.15 part Yield improver (manufactured by Hymo Corporation; NR11LS) 0.03 part

A base paper having a basis weight of 100 g / m ² and an ash content of 25.0% was prepared from a 0.5% by weight pulp slurry having the above composition by using a fourdrinier paper machine at a papermaking width of 1300 mm and a papermaking speed of 150 m / min. This was designated as “base paper 6”.

Next, transfer papers for wet electrophotography of Examples and Comparative Examples were prepared in the following manner. In the examples and the comparative examples, the amounts of the zirconium compound in the liquid mixture and the solid adhesion amount are based on ZrO ₂ conversion.

Example 1 A base paper 3 was subjected to size press using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid is 1.25 g.
/ m ² . The solid deposition amount of ammonium zirconium carbonate was 0.05 g / m ² in terms of ZrO ₂ . The wet electrophotographic transfer paper produced as described above was used in Example 1.
Transfer paper for wet electrophotography. <Blending of size press liquid> Oxidized starch (manufactured by Nippon Shokuhin Processing Co., Ltd .; MS3800) 3.0 parts Ammonium sirconium carbonate (manufactured by Nippon Light Metal Co., Ltd .; Baycoat 20) 0.13 parts Water 96.87 parts

Example 2 Size press was performed on base paper 3 using a liquid having the following composition. At this time, the solid pressing amount of the size press liquid is 1.40 g.
/ m ² . The solid attachment amount of ammonium zirconium carbonate was 0.20 g / m ² in terms of ZrO ₂ . The wet electrophotographic transfer paper prepared as described above was used in Example 2.
Transfer paper for wet electrophotography. <Composition of size press liquid> Oxidized starch (manufactured by Nippon Food Processing Co., Ltd .; MS3800) 3.0 parts Ammonium sirconium carbonate (manufactured by Nippon Light Metal Co., Ltd .; bay coat 20) 0.5 parts Water 96.5 parts

Example 3 A size press was performed on base paper 3 using a liquid having the following composition. At this time, the solid pressing amount of the size press liquid is 1.80 g.
/ m ² . The solid deposition amount of ammonium zirconium carbonate was 0.60 g / m ² in terms of ZrO ₂ . The wet electrophotographic transfer paper prepared as described above was used in Example 3.
Transfer paper for wet electrophotography. <Blending of size press liquid> Oxidized starch (manufactured by Nippon Shokuhin Processing Co., Ltd .; MS3800) 3.0 parts Ammonium sirconium carbonate (manufactured by Nippon Light Metal Co., Ltd .; bay coat 20) 1.5 parts Water 95.5 parts

Example 4 A size press was performed on base paper 3 using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid is 2.00 g.
/ m ² . The solid deposition amount of ammonium zirconium carbonate was 0.80 g / m ² in terms of ZrO ₂ . The wet electrophotographic transfer paper produced as described above was used as the wet electrophotographic transfer paper of Example 4. <Blending of size press liquid> Oxidized starch (manufactured by Nippon Food Processing Co., Ltd .; MS3800) 3.0 parts Ammonium sirconium carbonate (manufactured by Nippon Light Metal Co., Ltd .; bay coat 20) 2.0 parts Water 95.5 parts

Example 5 A base paper 3 was subjected to a size press using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid is 2.20 g.
/ m ² . The solid attachment amount of ammonium zirconium carbonate was 1.00 g / m ² in terms of ZrO ₂ . The wet electrophotographic transfer paper prepared as described above was used in Example 5.
Transfer paper for wet electrophotography. <Compounding of size press liquid> Oxidized starch (manufactured by Nippon Shokuhin Kabushiki Kaisha; MS3800) 3.0 parts Ammonium dicarbonate carbonate (manufactured by Nippon Light Metal Co., Ltd .; Baycoat 20) 2.5 parts Water 94.5 parts

Example 6 The wet electrophotographic transfer paper of Example 6 was prepared in the same manner as in Example 2 except that potassium zirconium carbonate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. Produced.

Example 7 The wet electrophotographic transfer paper of Example 6 was prepared in the same manner as in Example 7 except that potassium zirconium carbonate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. Produced.

Example 8 A wet electrophotographic transfer paper of Example 8 was prepared in the same manner as in Example 2, except that zirconium nitrate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. did.

Example 9 A wet electrophotographic transfer paper of Example 9 was prepared in the same manner as in Example 2 except that zirconium nitrate (manufactured by Nippon Light Metal Co., Ltd.) was used in place of ammonium zirconium carbonate. did.

Example 10 A wet electrophotographic transfer paper of Example 10 was prepared in the same manner as in Example 2 except that zirconium sulfate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. did.

Example 11 A wet electrophotographic transfer paper was produced in the same manner as in Example 2, except that zirconium sulfate (manufactured by Nippon Light Metal Co., Ltd.) was used in place of ammonium zirconium carbonate. .

Example 12 A wet electrophotographic transfer paper of Example 12 was prepared in the same manner as in Example 2 except that zirconium acetate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. did.

Example 13 A wet electrophotographic transfer paper of Example 13 was prepared in the same manner as in Example 2 except that zirconium acetate (manufactured by Nippon Light Metal Co., Ltd.) was used instead of ammonium zirconium carbonate. did.

Example 14 A wet electrophotographic transfer paper of Example 14 was produced in the same manner as in Example 3 except that the base paper 2 was used.

Example 15 A wet electrophotographic transfer paper of Example 15 was produced in the same manner as in Example 3 except that the base paper 4 was used.

Example 16 A wet electrophotographic transfer paper of Example 16 was produced in the same manner as in Example 3 except that the base paper 5 was used.

Comparative Example 1 Size press was performed on base paper 4 using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid is 1.20 g.
/ m ² . The wet electrophotographic transfer paper produced as described above was used as the wet electrophotographic transfer paper of Comparative Example 1. <Composition of size press liquid> Oxidized starch (manufactured by Nippon Food Processing Co., Ltd .; MS3800) 3.0 parts Water 97.0 parts

Comparative Example 2 Size press was performed on base paper 5 using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid is 1.20 g.
/ m ² . The wet electrophotographic transfer paper produced as described above was used as the wet electrophotographic transfer paper of Comparative Example 2. <Composition of size press liquid> Oxidized starch (manufactured by Nippon Food Processing Co., Ltd .; MS3800) 3.0 parts Water 97.0 parts

Comparative Example 3 Size press was performed on base paper 4 using a liquid having the following composition. At this time, the solid adhesion amount of the size press liquid was 1.23 g / m ² . The solid deposition amount of ammonium zirconium carbonate is 0.03 g / ZrO ₂ conversion.
m ² . The wet electrophotographic transfer paper prepared as described above was used as the wet electrophotographic transfer paper of Comparative Example 3. <Blending of size press liquid> Oxidized starch (manufactured by Nippon Shokuhin Processing Co., Ltd .; MS3800) 3.0 parts Sirconium ammonium carbonate (manufactured by Nippon Light Metal Co., Ltd .; Baycoat 20) 0.08 parts Water 96.92 parts

Comparative Example 4 A wet electrophotographic transfer paper of Comparative Example 4 was produced in the same manner as in Example 3 except that the base paper 1 was used.

Comparative Example 5 A wet electrophotographic transfer paper of Comparative Example 5 was produced in the same manner as in Example 3 except that the base paper 6 was used.

The ash content of the wet electrophotographic transfer paper produced as described above was measured with reference to JISP8128. According to JIS P8128, the temperature at which paper is burned is 900 ° C., but the “ash content” in the present invention is the result of burning at 550 ° C. and ashing a test specimen.

The toner fixability of the above wet electrophotographic transfer paper was evaluated by the following method.

1. Printing; As a printing machine, "E-print1" manufactured by Indigo
000 ". As a print image to be used for evaluation, an image having a solid print portion for each of four colors of black, cyan, magenta, and yellow was output. The printing area of the solid printing portion was set to be a square having a side of at least 3 cm or more.

As described above, “E-print10
00 ", black, cyan, magenta,
The following fixing evaluation was performed on the solid printing portion of each color of yellow.

2. Tape peeling evaluation Nichiban cellophane adhesive tape “Cellotape No. 405” with a width of 18 mm was stuck on the printed part of each color without any unevenness, and the tape was slowly peeled at a speed of about 5 mm / sec by 180 ° peeling. Was. The degree of fixation of the toner to the paper after peeling was visually determined, and a six-step evaluation was performed based on the following criteria. The level that is practically acceptable is “4” or more.

"6": Most of the toner for each color remains on the paper. "5": Although toner remains for each color, it can be seen that the print density of the printed portion after the tape is peeled is reduced. "4": The toner peeled off from the paper in some colors, and there was a white portion in the printed portion. "3": The toner peeled off from the paper for each color, and there was a white portion 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.

3. Rubbing evaluation The rubbing evaluation applied the horizontal method of JIS P8147 "Method of testing friction coefficient of paper and paperboard". In each of the examples and comparative examples, a blank wet electrophotographic transfer paper was attached to a horizontal plate, and the transfer paper having a printing portion printed by the above-described printing machine was attached to a weight.

When the transfer paper having the printing portion was attached to the weight, the printed surface of the printing portion was rubbed against the blank transfer paper attached to the horizontal plate.

After attaching the test piece to the horizontal plate and the weight as described above, the weight is slid on the horizontal plate under the conditions described in JIS P8147. In the "friction test", the weight is slid on the horizontal plate only once with one combination of test pieces, but in this evaluation, the weight is slid on the horizontal plate 50 times with one combination of test pieces. I let you.

Thereafter, the printed portion attached to the weight was observed, and the degree of toner falling off due to rubbing between the papers was observed. The remaining amount of the toner in the printing portion was visually determined, and a six-step evaluation was performed based on the following criteria. The level that is practically acceptable is “4” or more.

"6": A decrease in the density of the printed portion is hardly recognized for each color. "5": It can be seen that the print density is slightly reduced for each color. "4": It can be seen that the print density decreases for each color. "3": It can be seen that the print density is lowered for each color, and there are portions that are partially white. "2": It can be seen that the print density decreases for each color, and there are many white spots. "1": Toner is peeled off from the paper for each color, and there are very many white spots.

[0077]

[Table 1]

Table 1 summarizes the ash content of the transfer paper for wet electrophotography, the zirconium compound applied to the surface of the transfer paper, the amount of the coating in terms of ZrO ₂ , and the toner fixing evaluation results of the examples and comparative examples. .

Evaluation results: By comparing Examples 1 to 5 with Comparative Examples 1 and 3, it can be seen that the fixability of the toner is improved by coating zirconium ammonium carbonate on the paper surface. In order to obtain good toner fixability, the amount of zirconium ammonium carbonate to be applied is
0.05 g / m requires ² or more, its effect 1.00 g / m ² or more, it can be seen that become saturated.

Example 3, Examples 14-16 and Comparative Example 4,
By comparing No. 5, it can be seen that the ash content of the transfer paper for wet electrophotography is increased, so that the fixability of the toner is improved. The ash content of the transfer paper is required to be 5% or more, and the effect of improving the ash content up to 20% is recognized. However, when the ash content of the transfer paper is further increased, the fixability of the toner is rather deteriorated.

By comparing Examples 3 and 16 with Comparative Examples 1, 2, and 3, the toner fixability was improved by increasing the ash content, but this was not sufficient. It can be seen that zirconium ammonium needs to be applied in a predetermined amount or more.

By comparing Examples 2 and 3 with Examples 6 to 13, it is found that, similarly to ammonium zirconium carbonate, potassium zirconium carbonate, zirconium nitrate, zirconium sulfate and zirconium acetate can improve the toner fixing property. Recognize.

[0083]

From the above results, the wet electrophotographic transfer paper of the present invention is a wet electrophotographic transfer paper having an ash content in the paper of 5 to 20% by weight, and has a zirconium ammonium carbonate, Good fixability of the toner after printing by applying one of potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate in an amount of 0.05 to 1.00 g / m ^{2 in} terms of ZrO _2. It is characterized by.

Claims (1)

[Claims] 1. A wet electrophotographic transfer paper having an ash content in the paper of 5 to 20% by weight, and any one of ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate and zirconium acetate on the surface of the transfer paper. 0.05~1.00g one in terms of ZrO ₂ / m ²
Coated wet electrophotographic transfer paper characterized by being coated.