JP2005221728A - Electrophotographic transfer paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide non-coating type and coating type electrophotographic transfer paper having excellent toner transferability. <P>SOLUTION: In the non-coating type electrophotographic transfer paper, the base paper contains a pigment as filler having ≤0.80 g/ml bulk density by a natural deposition method based on JIS K5101 and having ≥1.10 compression rate of the transfer paper measured by a Parker Print Surf smoothness measurement instrument based on ISO 8791-4:1992. In the coating type electrophotographic transfer paper, the coating layer contains a pigment having ≤0.80 g/ml bulk density as a component by ≥20 parts by weight with respect to 100 parts by weight of the entire pigments, and the transfer paper has ≥1.20 compression rate of the paper measured by a Parker Print Surf smoothness measurement instrument based on ISO 8791-4:1992. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic transfer paper. More specifically, non-coating and coating-type electrophotography that can be printed by electrophotographic printers, fax machines, copiers, and on-demand printers using dry toner and have excellent toner transferability. It relates to transfer paper.

  Output by electrophotography is rapidly expanding due to the spread of printing from personal computers and on-demand printing.

  Up to now, high-quality output media has been preceded by the sublimation thermal transfer system, which has been used in the field of medical image processing, etc. It was a point.

  Recently, coupled with dramatic improvements in resolution and ink droplet miniaturization technology, the inkjet printing method is approaching photographic image quality, and several photo systems have been put on the market due to their low running costs. . However, although the inkjet method is inexpensive, the problem that the printing process takes time has not been solved.

  The electrophotographic method, which is relatively inexpensive and has a short print processing time, has attracted attention as a full-color output method that emphasizes visuals as well as the conventional text-centric output. Also in the electrophotographic system, the resolution improvement and the toner miniaturization technology are surely progressing, and due to its active development status, it is predicted that it will eventually approach the ink jet printing system and the offset printing system. In the electrophotographic system, an original latent image is formed on a semiconductor material, and a visible toner image is formed by toner. The toner image has a negative or positive charge. When the toner image is transferred onto an image receiving material having a charge opposite to the toner image, the toner image is once transferred onto an intermediate transfer material and then further transferred onto the image receiving material. There is a case. Toner is transferred to the image receiving material by the electrostatic force of the oppositely charged toner and the image receiving material, but in actuality, the toner image on the semiconductor material or intermediate transfer body and the image receiving material are in close contact with each other by mechanical pressure. Also shows an important role. Finally, the toner is fixed on the image receiving material by the action of either heat or pressure, or both.

As a technique for improving the transfer efficiency of the toner image to the image receiving material, the volume electric resistance value, surface electric resistance value, smoothness, and voids of the coating layer of the image receiving material are specified, and attempts to improve this are relatively long. Several studies have been conducted and some reports have already been made. However, due to the tandem layout of the photosensitive device, the printing speed has been improved in recent years, and the contact time between the toner image and the image receiving material has been increased as the electrophotographic printing machine exceeding 20 to 50 pages per minute is put into practical use. As a result, the design of the image receiving material that has been considered so far has not been satisfactory as a technique for further improving the transfer efficiency of the toner image. In particular, the electric resistance value of the image receiving material depends on changes in humidity and temperature, and there is a limit to stabilizing the transfer efficiency of a high-speed type printing machine only by the regulation. (For example, refer patent documents 1-11.).
Japanese Patent No. 2041908 Japanese Patent No. 2218894 Japanese Patent No. 2136848 Japanese Patent No. 2676291 Japanese Patent No. 3227380 Japanese Patent No. 3232514 JP-A-8-171225 JP 2000-172001 A JP 2002-67233 A JP 2002-341582 A JP 2002-357916 A

  An object of the present invention is to provide a non-coating type and a coating type that can be printed by an electrophotographic printer, a fax machine, a copying machine, an on-demand printing machine using dry toner, and have excellent toner transferability. An electrophotographic transfer paper is provided.

  As a result of intensive studies in view of the above, the present inventors have invented the electrophotographic transfer paper of the present invention.

  That is, the electrophotographic transfer paper of the present invention has a natural deposition method according to JIS K5101 as a filler in a non-coating type configuration in which a coating layer mainly composed of pigment is not provided on the surface of the base paper. The transfer paper has a density of 0.80 g / ml or less in density (hereinafter referred to as bulk) and the compression ratio of the transfer paper measured by a smoothness measuring device Parker Print Surf conforming to ISO 8791-4: 1992 is 1. It is characterized by being 10 or more.

  In addition, in a coating type configuration in which a coating layer mainly composed of one or more pigments is provided on at least one surface of the base paper, a pigment having a coating layer of 0.80 g / ml or less conforming to JIS K5101 is used as a component of the coating layer. The transfer paper has a compressibility of 1.20 or more as measured by a smoothness measuring device Parker Print Surf according to ISO 8791-4: 1992, containing 20 parts by weight or more with respect to 100 parts by weight of the total pigment. It is characterized by.

  Furthermore, in a coating type configuration in which a coating layer mainly composed of one or more pigments is provided on at least one side of the base paper, a pigment that is less than 0.80 g / ml in accordance with JIS K5101 is used as a filler for the base paper. In addition, 20 parts by mass or more of a pigment of 0.80 g / ml or less based on JIS K5101 is contained as a component of the coating layer with respect to 100 parts by mass of the total pigment, and conforms to ISO 8791-4: 1992 The compression rate of the transfer paper measured by a smoothness measuring device Parker Print Surf is 1.20 or more.

  As described above, the electrophotographic transfer paper of the present invention can be printed by an electrophotographic printer, a fax machine, a copier, and an on-demand printer using dry toner, and has an excellent toner transfer property and is not coated. It is a transfer paper for electrophotography of a working type and a coating type.

  Hereinafter, the electrophotographic transfer paper of the present invention will be described in detail.

  In the electrophotographic method, an original latent image is formed on a semiconductor material, and a visible toner image is formed by toner. The toner image has a negative or positive charge. When the toner image is transferred onto an image receiving material having the opposite charge, the toner image is once transferred onto an intermediate transfer material and then further transferred onto the image receiving material. There is a case. The transfer of toner to the image receiving material is performed by the electrostatic force of the oppositely charged toner and the image receiving material, but in reality, the toner image on the semiconductor material or intermediate transfer body and the image receiving material are in close contact with each other by mechanical pressure. Also shows an important role. With the aim of higher image quality, the development of toner technology is progressing in the direction of miniaturization. As a result, the image layer for forming a toner image is also made thinner. Also, due to the tandem layout of the photosensitive device, the printing speed has been improved in recent years, and the contact time between the toner image and the image receiving material has been increased as the electrophotographic printing press exceeding 20 to 50 pages per minute is put into practical use. As the toner image becomes shorter, the adhesion between the toner image and the image receiving material, i.e., the transfer paper, becomes more and more important for improving the toner transfer efficiency.

  In the present invention, the compression rate of the transfer paper measured by a smoothness measuring device Parker Print Surf in accordance with ISO 8791-4: 1992 is 1.10 or more for the non-coating type, and 1 for the coating type. .20 or more, when the toner image on the semiconductor material or the intermediate transfer member and the image receiving material are brought into close contact with each other by mechanical pressure, the transfer paper exhibits appropriate cushioning and adhesiveness. Exhibits stable toner transferability.

  Here, the compression ratio is a method using Parker Print Surf which measures the roughness (smoothness) using two types of clamp pressure at the same point of one sample and knows the compressibility of the transfer paper surface from this ratio. Obtained by dividing the roughness (smoothness) measured at a low clamping pressure by the roughness (smoothness) measured at a high clamping pressure. The ratio of low clamp pressure to high clamp pressure is 1: 2. Soft backing is used for uncoated samples and hard backing is used for coated samples.

  When the transfer paper of the present invention is a non-coating type, in order to improve the compression rate of the transfer paper, an internal filler whose compliant with JIS K5101 is 0.80 g / ml or less is used. In order to improve the toner transfer rate of non-coated paper type transfer paper, there are several methods for improving the compression rate. However, a method using such a specific bulk pigment as an internal filler is used for transfer paper. It is most suitable as a technique for improving the toner transferability particularly remarkably because the compression ratio is easily balanced with other physical properties such as transfer paper smoothness, air permeability, whiteness, and fading. Even in the case of the coating type, the toner transferability is greatly improved by adding a similar internal filler.

  In the present invention, examples of the internal filler that can be used include calcium carbonate, magnesium carbonate, kaolin, delaminated kaolin, calcined kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, Satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, colloidal silica, colloidal silica modified with cation, aluminum hydroxide, alumina, alumina hydrate, lithopone, zeolite, hydrohalosite, magnesium hydroxide, etc. White inorganic pigments, organic pigments, and the like. An organic pigment having a hollow shape is also preferably used. The addition amount is preferably 2 to 30% by mass, more preferably 5 to 20% by mass in terms of ash according to JIS P8003. If the addition amount is less than this, it is difficult to improve the transfer paper compression rate and improve the transfer efficiency of toner to the transfer paper in the printing machine. If it is more than this, the strength of the base paper may be reduced. is there.

  Examples of the internally added sizing agent used in producing the electrophotographic transfer paper of the present invention include rosin sizing agent in the case of acidic papermaking, alkyl ketene dimer, alkenyl anhydride succinic acid in the case of neutral papermaking. Examples include acids, neutral rosin sizing agents, and cationic styrene acrylics.

  In addition to the above, in the stock used when producing the electrophotographic transfer paper of the present invention, a yield improver and various anions that have been used conventionally are within the range that does not impair the desired effects of the present invention. The internal additive for papermaking, such as water, nonionic, cationic or amphoteric drainage improver and paper strength improver, is appropriately selected and used as necessary. For example, various starches, and one or more of polyacrylamide, polyethyleneimine, polyamine, polyamide / polyamine, urea formalin resin, melamine formalin resin, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, polyamide resin are appropriately used. Used in combination.

  Further, as a technique for improving the compression rate of the transfer paper, there is a means for increasing the paper volume by adding a bulking agent. As the bulking agent, a surfactant which is a compound having a hydrophilic group and a hydrophobic group is often used. However, since the bulking agent produces a bulking effect by inhibiting hydrogen bonding between fibers, the paper strength is significantly reduced, and it is necessary to use a paper strength agent or the like to compensate for it.

  In the electrophotographic transfer paper of the present invention, the coating layer mainly composed of pigment is one in which the proportion of the pigment contained in the coating layer is 50 parts by mass or more with respect to 100 parts by mass of all coating layer components. Point to. The surface of the non-coating type electrophotographic transfer paper and the surface of the base paper of the coating type electrophotographic transfer paper are not provided with a coating layer mainly composed of pigment, but oxidized starch and etherified starch. , Esterified starch, cationic starch, phosphate starch, phosphated starch, modified starch, modified starch, casein, polyvinyl alcohol, and other binders, styrene / acrylic acid copolymers, styrene / methacrylic acid copolymers , Surface sizing agents such as acrylonitrile / vinyl formal / acrylic ester copolymer, styrene / maleic acid copolymer, dimensional stabilizers such as ethylene-urea resin, inorganic conductive agents such as sodium chloride and potassium chloride, organic conductive Of course, it is possible to apply an agent, a surfactant, and a dye alone or in combination. Less than 50 parts by weight relative to the amount unit, preferably no problem include is less than 30 parts by weight.

  As a device for coating the binder and the surface sizing agent, a conventional size press, a gate roll size press, or a size press of a metade film transfer system, a rod coater, a bill blade, a short dwell coater, a blade coater, an air knife coater. A curtain coater or the like can be preferably used.

  The pulp that can be used when producing the electrophotographic transfer paper of the present invention includes NBKP, LBKP, NBSP, LBSP, GP, TMP and the like, as well as non-wood pulp such as kenaf and bagasse, and waste paper pulp. These are used alone or in combination as necessary. In order to increase the compression ratio of transfer paper, bulky mechanical pulp such as GP and TMP, semi-mechanical pulp, kenaf, bagasse non-wood pulp, lyocell, cellulose, etc. It is an effective means to use.

  In addition, as a raw material of the used paper pulp said by this invention, the white paper, ruled white, cream white, card | curd, special white, medium white, imitation shown by the used paper standard quality specification table | surface of a used paper reproduction promotion center , Fair white, Kent, white art, special upper limit, another upper limit, newspaper, magazine and so on. Specific examples include non-coating computer paper, which is information-related paper, printer paper such as thermal paper and pressure-sensitive paper, OA waste paper such as PPC paper, art paper, coated paper, finely coated paper, matte paper, etc. Non-coated paper such as coated paper or high-quality paper, color quality, notebook, notepaper, wrapping paper, fancy paper, medium-quality paper, newsprint, reprint paper, supermarket paper, imitation paper, pure white roll paper, milk carton For example, chemical pulp paper, high-yield pulp-containing paper, and the like are used, but there is no particular limitation on printing, copying, printing, or non-printing.

  In the papermaking method of the electrophotographic transfer paper of the present invention, the paper machine can be a paper machine known in the paper industry such as a long paper machine, a twin wire paper machine, a combination paper machine, a round paper machine, a Yankee paper machine, etc. .

  As a method for improving the compression rate of the transfer paper in terms of machine operation, there are means such as reduction of the press linear pressure during paper making and softening of the calendar process.

  The electrophotographic transfer paper of the present invention has a coating layer mainly composed of one or more pigments on at least one side in order to obtain glossiness, whiteness, opacity and smoothness with the aim of improving the aesthetics of the printed matter. Can be provided.

  When the electrophotographic transfer paper of the present invention is a coated paper, 20 parts by mass or more of a pigment having a coating layer of 0.80 g / ml or less based on JIS K5101 is used as a component of the coating layer. use. When the blending amount is smaller than this, it becomes difficult to improve the compression rate of the electrophotographic transfer paper and improve the toner transfer efficiency in the printing press. In order to improve the toner transfer rate of coated paper type transfer paper, there are several methods for improving the compression rate. However, a method using such a specific amount of pigment in a specific blending amount is not suitable for the transfer paper. It is most suitable as a technique for easily maintaining the balance between the improvement of the compression ratio and the coating layer strength and particularly remarkably improving the toner transferability.

  In the present invention, examples of the pigment used in the coating layer include calcium carbonate, magnesium carbonate, kaolin, delaminated kaolin, calcined kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, and carbonate. Zinc, satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, colloidal silica, cation-modified colloidal silica, aluminum hydroxide, alumina, alumina hydrate, lithopone, zeolite, hydrohalosite, hydroxylation Examples thereof include white inorganic pigments such as magnesium and organic pigments. An organic pigment having a hollow shape is also preferably used.

  Here, examples of the adhesive include starch derivatives such as oxidized starch, etherified starch, esterified starch, and phosphate esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol or Derivatives thereof; conjugated diene copolymer latex such as polyvinylpyrrolidone, maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylate ester and methacrylate ester, etc. Acrylic polymer latex; vinyl polymer latex such as ethylene-vinyl acetate copolymer; or functional group-modified polymer latex with functional group-containing monomers such as carboxyl groups of these various polymers; Is a product obtained by cationizing these various polymers with a cationic group, a product obtained by cationizing a polymer surface with a cationic surfactant, or polymerizing the polymer under cationic polyvinyl alcohol to distribute the polyvinyl alcohol on the polymer surface. Polymerized in a suspension dispersion of cationic colloidal particles, and the particles are distributed on the surface of the polymer; aqueous adhesives such as thermosetting synthetic resins such as melamine resin and urea resin; Polymer or copolymer resin of acrylic acid ester or methacrylic acid ester such as polymethyl methacrylate; synthetic resin adhesive such as polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin, etc. They can be used alone or in combination.

  In order to design the transfer paper with a high compression ratio, the amount of adhesive added is desirably 25 parts by mass or less, more preferably 15 parts or less, based on 100 parts by mass of the total pigment, and the adhesive itself is elastic. For example, those having a relatively low glass transition point are desirable.

  In addition, on the outermost layer, as other additives, pigment dispersant, thickener, fluidity improver, antifoaming agent, foam suppressor, mold release agent, foaming agent, penetrating agent, coloring dye, coloring pigment, Ultraviolet absorbers, antioxidants, preservatives, antibacterial agents, water resistance agents, dye fixing agents, inorganic and organic conductive agents, lubricants, and the like can also be appropriately blended.

  Examples of other additives include pH adjusters, metal sequestering agents, antifungal agents, viscosity modifiers, surface tension modifiers, wetting agents, surfactants, and rust inhibitors.

  When a coating layer is provided on the transfer paper, the coating method and the coating amount are not particularly limited, and a conventional size press, gate roll size press, or a metade film transfer type size press, roll coater, gravure coater. Rod coaters, bill blades, short dwell coaters, blade coaters, air knife coaters, curtain coaters, cast coaters, spray coaters, etc. are used as appropriate. May be. Moreover, the coating amount is not particularly limited.

  Furthermore, in order to obtain smoothness and glossiness, a super calender, soft nip calender, multi-stage soft nip calender, machine calender, rewet cast, etc. can be used as appropriate. Further, when the rolls of these finishing devices are heated, the nip line pressure can be set low, and the transfer paper having a high compression rate can be finished.

  In addition, the completed electrophotographic transfer paper has high gloss, embossed gloss, durability, weather resistance, water resistance, oil resistance, or chemical and physical properties intended to improve transferability and fixability of specific toners. Optical, electrical and magnetic treatments can be applied.

Although there is no restriction | limiting in particular in the thickness of a transfer paper, Usually, about 40-350 g / m < ² > paper is used by basic weight. Preferably, the basis weight is 70 to 250 g / m ² .

  The electrophotographic transfer paper in the present invention is not limited to use as a dry electrophotographic transfer paper for an output device such as a copy, a printer, an on-demand printer, a fax machine, a wet electrophotographic transfer paper, an offset printing paper, It can be used as gravure printing paper and thermal transfer image receiving paper. It is also possible to apply a pressure-sensitive adhesive layer on the surface opposite to the printing application and apply it to the label application.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified. The “bulk” shown in the examples is the value of the pigment bulk obtained by a measuring method based on JIS K5101.

(Example 1) to (Example 2) and (Comparative Example 1) to (Comparative Example 2)
LBKP (Drainage 440 mlcsf) 70 parts NBKP (Drainage 490 mlcsf) 30 parts Light calcium carbonate (indicated by ash content in base paper) 9 parts Commercial cationized starch 0.7 parts Commercial cationic polyacrylamide yield improver 0.03 parts Pulp and internal chemicals were adjusted according to the above formulation, and (1) to (4) base papers having a basis weight of 120 g / m ² were made. In addition, regarding the light calcium carbonate, the following were blended in each example.
Base paper (1): Light calcium carbonate A (bulk: 0.2 g / ml)
Base paper (2): Light calcium carbonate B (bulk: 0.8 g / ml)
Base paper (3): Light calcium carbonate C (bulk: 1.0 g / ml)
Base paper (4): Light calcium carbonate D (bulk: 1.2 g / ml)
By adjusting the press pressure and calendar pressure during the process, the compression rate shown in Table 1 was adjusted, and the transfer paper of Example 1 from the base paper (1) was similarly changed to (2), (3), (4). The transfer paper of Example 2, Comparative Example 1, and Comparative Example 2 was manufactured.

(Example 3)
<Coating fluid A>
Heavy calcium carbonate (bulk: 0.4 g / ml) 80 parts Kaolin (bulk: 0.3 g / ml) 20 parts Commercially available polyacrylic acid dispersant 0.1 parts Commercially available adhesive (SBR latex) 10 parts Commercially available poly Acrylic thickener 0.1 parts Commercial lubricant (calcium stearate) 1.0 part Commercial fluorescent whitening agent (sulfonic acid derivative system of aminostilbenzene) 0.5 part Adjusted to pH 9.6 with sodium hydroxide A coating solution A was obtained.

On the base paper (3), the coating liquid A having the above composition was coated on both sides with a blade coating device so that the coating amount per side was 12.5 g / m ² and dried. Next, the nip linear pressure and roll temperature of the super calender were adjusted so that the compression ratio shown in Table 1 was achieved, and the super calender treatment was performed to obtain a transfer paper of Example 3.

Example 4
<Coating fluid B>
Heavy calcium carbonate (bulk: 0.9 g / ml) 80 parts Kaolin (bulk: 0.3 g / ml) 20 parts Commercial polyacrylic acid dispersant 0.1 parts Commercial adhesive (SBR latex) 10 parts Commercial poly Acrylic thickener 0.1 parts Commercial lubricant (calcium stearate) 1.0 part Commercial fluorescent whitening agent (sulfonic acid derivative system of aminostilbenzene) 0.5 part Adjusted to pH 9.6 with sodium hydroxide Coating solution B was obtained.

On the base paper (3), the coating liquid B having the above composition was coated on both sides with a blade coating device so that the coating amount per side was 12.5 g / m ² and dried. Next, the nip line pressure and roll temperature of the super calender were adjusted so that the compression ratios shown in Table 1 were obtained, and super calender treatment was performed to obtain a transfer paper of Example 4.

(Comparative Example 3)
<Coating fluid C>
Heavy calcium carbonate (bulk: 0.9 g / ml) 100 parts commercial polyacrylic acid dispersant 0.1 parts commercial adhesive (SBR latex) 10 parts commercial polyacrylic thickener 0.1 parts commercial lubricant (Calcium stearate type) 1.0 part Commercial fluorescent whitening agent (sulfonic acid derivative type of aminostilbenzene) 0.5 part Sodium hydroxide was adjusted to pH 9.6 and used as coating solution C.

On the base paper (3), the coating liquid C having the above composition was coated on both sides with a blade coating device so that the coating amount per side was 12.5 g / m ² and dried. Next, the nip linear pressure and roll temperature of the super calender were adjusted so that the compression ratios shown in Table 1 were obtained, and super calender treatment was performed to obtain a transfer paper of Comparative Example 3.

(Example 5)
On the base paper (1), the coating liquid A was coated on both sides with a blade coating device so that the coating amount per side was 12.5 g / m ² and dried. Next, the nip line pressure and roll temperature of the super calender were adjusted so that the compression ratios shown in Table 1 were achieved, and super calender treatment was performed to obtain a transfer paper of Example 5.

  With respect to the electrophotographic transfer papers of Examples 1 to 5 and Comparative Examples 1 to 3 produced as described above, the compression ratio and the image unevenness were measured by the following measurement methods, and the evaluation results are shown in Table 1.

1) Compressibility A smoothness measuring instrument Parker Print Surf conforming to ISO 8791-4: 1992 was used. For non-coated Examples 1 and 2 and Comparative Examples 1 and 2, soft backing was used. Moreover, about Examples 3-5 and the comparative example 3 which applied, the hard backing was used. The compression ratio was obtained by dividing the roughness (μm) at a clamp pressure of 10 kg / cm ^{2 by} the roughness (μm) at a clamp pressure of 20 kg / cm ² . The humidity control environment and measurement environment of the sample are 23 ° C. and 50 RH%.

2) Image irregularity Canon: A solid image of black, cyan, magenta, and yellow was printed by passing through a blank sample of A4 length on a CP-2150 machine. The humidity and temperature of the sample were measured in the three environments shown in Table 1. Image transfer unevenness was evaluated according to the following 6 levels.
“6”: There is no image unevenness in each color.
“5”: Image unevenness is slightly observed in some colors.
“4”: Image unevenness is slightly observed in two or more colors.
“3”: Image unevenness is slightly observed for each color.
“2”: Image unevenness is partially observed for each color.
“1”: The entire image is uneven for each color.

Rating:
In Examples 1 to 5, due to the excellent compressibility, very good toner transfer was exhibited under normal conditions of 23 ° C. and 50% RH, and good print quality with little image unevenness was exhibited. Further, the transfer paper showed good transferability even under the other two conditions, which were severe conditions with respect to the toner transfer efficiency, because the electric resistance value of the transfer paper fluctuated. In particular, Example 5 satisfying claim 3 exhibited very excellent print quality in each environment. On the other hand, in Comparative Examples 1 to 3, since the compressibility is inferior, image unevenness occurs, and in particular, in a low humidity and high humidity environment where the toner transferability is severe, a marked decrease in image quality was observed.

  It can be used as electrophotographic transfer paper in various printing areas.

Claims (3)

  In a non-coating type electrophotographic transfer paper in which a coating layer mainly composed of a pigment is not provided on the surface of the base paper, the base paper is a natural deposition method bulk density (hereinafter referred to as bulk) according to JIS K5101 as a filler. Wherein the transfer paper has a compression ratio of 1.10 or more as measured by a smoothness measuring device Parker Print Surf according to ISO 8791-4: 1992. Transfer paper for electrophotography.   In a coating type electrophotographic transfer paper in which a coating layer mainly composed of one or more pigments is provided on at least one side of the base paper, whether it complies with JIS K5101 as a component of the coating layer is 0.80 g / ml or less The transfer paper has a compression ratio of 1.20 or more, as measured by a smoothness measuring instrument Parker Print Surf according to ISO 8791-4: 1992. An electrophotographic transfer paper characterized by the above.   In a coating type electrophotographic transfer paper in which a coating layer mainly composed of one or more pigments is provided on at least one side of the base paper, it is less than 0.80 g / ml as a base paper filler according to JIS K5101 20 parts by mass of a pigment containing a pigment and having a bulk density (hereinafter referred to as bulk) of 0.80 g / ml or less in accordance with JIS K5101 as a component of the coating layer. A transfer paper for electrophotography, wherein the transfer paper has a compression ratio of 1.20 or more as measured by a smoothness measuring instrument Parker Print Surf according to ISO 8791-4: 1992.