JPH07120064B2 - Electrophotographic transfer paper - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer paper used in an electrophotographic method, particularly a positive polarity toner developing type electrophotographic method.

2. Description of the Related Art Conventionally, an electrophotographic copying machine mainly uses an Se-based photoconductor or the like and employs a negative polarity toner system.

On the other hand, a method of forming a negative electrostatic latent image by using a two-layer photoconductor (function-separated photoconductor), a polyvinylcarbazole-based organic photoconductor, a zinc oxide photoconductor, a cadmium sulfide photoconductor, or a Se-based photoconductor. There is a positive toner developing type electrophotographic method in which a positive electrostatic latent image is formed using a body or the like and then reversal development is performed.

However, the fog of the non-image portion (background) of the copy, which is almost no problem in the conventional negative polarity toner developing type copying machine, in such a positive polarity toner developing type electrophotographic copying machine. And the like, and the copy quality deteriorates.

Therefore, the present inventors have paid attention to the fact that the paper powder adhered to the photoreceptor is not sufficiently cleaned in the toner image transfer step, or the paper powder is mixed in the developer by reusing the cleaned toner. When a conventional electrophotographic transfer paper is used in a layer toner developing type electrophotographic copying machine, paper powder components, especially talc (3MgO ・ 4SiO ₂・ H), which is a filler in the paper, is used.
₂ O) is negatively charged due to friction, contact, separation, etc. with the toner or carrier, resulting in agglomeration of paper powder and toner, or an increase in reverse polarity toner, which is developed in the background. We found that the copy quality was poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer paper for electrophotography, in particular, a positive polarity toner developing system, which is capable of removing and improving the defects of the conventional transfer paper based on the above-mentioned knowledge and obtaining good copy quality.

Structure of the Invention The transfer paper used in the electrophotographic method of the positive polarity toner developing method of the present invention is such that the paper is filled with calcium carbonate having a positive charge due to frictional charging with the toner or the carrier, and the alkyl ketene dimer is used as the size. It is characterized by

In the case of a two-component developer, as a carrier of the positive polarity toner developing system, it is known that iron powder or the like is coated with a polymer such as a fluororesin located at the lower side of the negative side in the charging train. Further, as a carrier of the negative polarity toner developing system, it is known that iron powder or the like is coated with a polymer such as acrylic resin which is located on the upper side on the positive side in the charging sequence. The toner is composed of a coloring material such as carbon and a binder such as acrylic resin, styrene resin and epoxy resin, and most of the toners have a charge train located between the positive and negative carriers.

In many cases, the toners in the one-component developer and the microtoning developer also have a charge train located near the toner of the two-component developer.

Electrified charge is blow-off method (Karakida; developer measurement method, No. 10)
It is measured by the 3rd IEEJ Workshop, June 3rd, 1980. It is not possible to measure the charge of two small particles, but the charge can be determined by using an appropriate standard product. It is considered that the charge train is based on the property peculiar to a substance.Those with a large dielectric constant and hygroscopicity are likely to be positively charged, and electronegativity, that is, those with a strong electron accepting property are likely to be negatively charged. It is known that a substance having a strong electron donating property is likely to be positively charged.

The present inventors measured the charged electric charges of various fillers added to the paper by the blow-off method using the above-mentioned positive and negative carriers. The results are shown in Table 1.

As is clear from the table, it was found that talc, which is a filler used in the conventional electrophotographic transfer paper, produces a negative charge. Kaolin clay and white carbon are also negatively charged. On the other hand, titanium dioxide, heavy calcium carbonate and light calcium carbonate are positively charged. However, chalk, which is another type of calcium carbonate, is negatively charged.

Table 2 shows the results of examining the fog of a copy by copying with a two-layer photoconductor electronic copying machine using a positive polarity toner two-component developer in which 50% and 500 mg of these various fillers are mixed in 5 kg of a developer.
As shown in (A; Background dirt and fine cutout of copy image are not present at all. B; Background dirt and /
Or, there are some small gaps in the copied image, but there is no problem in practical use. C: Background dirt and / or fine omissions in the copied image are slightly visible, but can be used for some purposes. D: The background is unusable due to frequent stains and / or fine cuts in the copied image. As is clear from Table 2, when talc, white carbon and kaolin clay were mixed with the positive polarity toner developer, copy quality defects such as background fogging occurred although there were some differences depending on the amount. On the other hand, in the case of titanium dioxide, calcium carbonate, which has a positive charge due to triboelectrification with the toner or carrier, the background fogging was practically acceptable.

The content of these fillers is 15% or less by weight of paper,
It is preferably 10% or less (see JP-A-55-13354).

In addition, the raw material composition, preparation, and control of manufacturing conditions are performed to impart suitability for electrophotographic copying machines such as copy suitability, running property, and curl property (JP-B-44-3673, JP-B-4).
6-24199, JP-B-55-47385, JP-A-55-142799).

That is, in order to maintain an appropriate copy image density and prevent the background (white paper part) from becoming dirty, sodium chloride,
The surface electrical resistance (according to JIS C-2111) of transfer paper is 10 ⁹ -10 ¹⁰ Ω (by applying a conductive agent such as potassium chloride, styrene-maleic acid copolymer, quaternary ammonium salt, etc. on the surface with a size press of a paper machine. Humidity (RH) 65%, temperature 20 ℃). Also, in order to improve the sharpness of the copy image area, the unevenness of the surface is reduced and the smoothness of the transfer paper (according to JIS P-8119) is set to 20 seconds or more. Also, if swelling or curling occurs due to partial moisture absorption of the transfer paper, the closeness of contact between the photoconductor of the copying machine and the transfer paper will decrease during transfer, causing a decrease in copy image density or partial omission of the copy. To prevent this, make the water content of the paper 4.5 to 5.5% and wrap it in moisture-proof wrapping paper to prevent moisture absorption and desorption during storage.

Next, the electrophotographic transfer paper of the present invention will be described with reference to Examples and Comparative Examples (Examples 1 to 3 and Comparative Examples 1 and 2).

Five types of transfer papers were prepared by using the filler composition, the pulp composition, the internally added sizing agent and the surface sizing agent as shown in Table 3 (Examples 1 to 3). Physical properties of this paper (grammage,
Table 3 shows the results of evaluation of the fogging of the paper for the 10,000th copy when copying was performed using a positive polarity toner two-component developer with a two-layer photoconductor copying machine. As a comparative example, Table 3 also shows the results obtained by performing the same measurement on two kinds of commercially available papers (PPC paper from Company A, general high-quality paper) (LBKP; bleached hardwood kraft pulp, NBKP; bleached softwood kraft pulp, AKD; Alkyl ketene dimer and the symbols A, B and C for copy fog have the same meanings as in Table 2.)

As described above, the electrophotographic transfer paper of the positive polarity toner developing system of the present invention is filled with calcium carbonate having a positive charge due to frictional charging with the toner or the carrier, and the alkyl ketene dimer is added internally. This transfer paper is contained as an agent, and according to this transfer paper, a high-quality image can be obtained without causing background stains on the copy and fine omission of the copied image, and obtaining a good electrophotographic copying machine suitability. be able to.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsukasa Matsuda 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Plant (72) Inventor, Ryuji Ohashi 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd.Ebina Co., Ltd. In the factory (56) References JP-A-51-13244 (JP, A) JP-A-53-46734 (JP, A)

Claims (1)

[Claims] 1. A positive polarity toner developing type electrophotographic transfer characterized in that a paper is filled with calcium carbonate having a positive charge due to triboelectrification with a toner or a carrier, and an alkyl ketene dimer is used as a sizing agent. paper.