JPH07209897A - Electrophotographic transfer paper - Google Patents

Abstract

PURPOSE:To ensure superior characteristics for curl at the time of copying by specifying the amt. of water removed from the front side of stock paper with a hybrid paper making machine and specifying the ash content distribution of transfer paper in the thickness direction. CONSTITUTION:The filler content of paper is 5 to 10wt.%. The amt. of water removed from the front side of stock paper is regulated to be 5 to 20% of the total amt. of water removed With a hybrid paper making machine and the ash content distribution of transfer paper in the thickness direction is regulated so that the ratio between the ash content of the front side and that of the rear side is made 4:6 to 6:4. In this case, the stock paper is prepd. using one or more kinds of pulps, e.g. chemical pulp such as LBKP or NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP or CGP and wastepaper pulp such as DIP. A filler may be added to the transfer paper so as to improve the flexibility or opacity of the paper and the filler is, e.g. an inorg. pigment such as heavy calcium carbonate, light calcium carbonate, talc, kaolin, clay, white carbon, titanium dioxide or diatomaceous earth.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a transfer sheet for electrophotography. More specifically, it relates to improvement in curl of electrophotographic transfer paper.

[0002]

2. Description of the Related Art In an electrophotographic recording system, a photosensitive drum having a surface layer of a photoconductive material and a conductive substrate is charged by irradiation of corona discharge ions, and an image pattern is irradiated on the photosensitive drum as an optical image. The toner is attached to the surface charge image formed on the photosensitive drum to develop the image, the image is transferred to a recording medium, and the image is fixed by heat or pressure to obtain a record.

In recent years, the electrophotographic recording system has been used in various devices such as OA copying machines, page printers, and facsimiles, and is excellent in various characteristics such as handling as plain paper, fixability, and storability. It has a large weight in the field.

Along with this, there are various required characteristics from the surface of the electrophotographic transfer paper. Required characteristics include running property, transfer property, fixing property, image quality of copy, and appearance.
Some of these properties depend on the properties of the paper itself, such as thickness, density, stiffness, smoothness, curl, size, wrinkles, lumpiness, whiteness, glossiness, and the like.

The electrophotographic transfer paper has a tendency that paper powder adheres to the photoconductor at the time of transfer of the development formed on the photoconductor, thereby causing image deletion. A method for improving these phenomena is disclosed in JP-A-60-6176.
Japanese Unexamined Patent Publication No. 2 (1993) describes that talc is used as a filler and the ash content is 3% or less based on the absolute dry weight of paper.

Further, the generation of the paper dust of the transfer paper adheres to the roll or the belt to cause a paper feeding failure phenomenon. The amount of paper dust generated on the transfer paper is closely related to the amount of the filler contained in the transfer paper.
In the gazette, the ash content of the transfer paper is 3 with respect to the absolute dry weight of the paper.
It is described that the transfer paper having an excellent running property can be obtained by suppressing the generation of paper dust by setting the content to ˜7%.

Further, when the paper dust of the transfer paper is generated, the paper dust is mixed with the developer to cause fog or the like on the back ground and the copy quality is deteriorated. Japanese Patent No. 40312 describes filling transfer paper with calcium carbonate having a positive charge.
Further, Japanese Patent Publication No. 2-50467 discloses a particle size of 20 μm.
It is described that the above filler is 1% by weight or less in the total filler. In addition, Japanese Patent Publication No. 3-8540 discloses 6
Filled with less than or equal to 5% by weight of calcium carbonate and 4% by weight of ash
The following is described.

Further, when feeding the transfer sheets accumulated in the copying machine, two or more sheets are fed at a time when the transfer sheets accumulated from the uppermost part are fed to the copying section of the copying machine. As a method for preventing the so-called "double feed" trouble, which is described in JP-B-2-48892, 2 to 10% by weight of a silica pigment having a particle size of 1 µ or less is internally added, or the paper surface is It is described that several papers coated with 0.5 to 3% by weight are superposed and cut.

The electrophotographic copying machine employs a system in which an image is formed on a transfer sheet with a toner and then the toner is heated and pressed to fix the toner on the sheet. This temperature is usually heated to 180 ° C. or higher. It That is, the transfer paper is passed between the metal roll and the elastic roll heated to a high temperature after the image formation with the toner. At this time, the transfer paper is heated so that the water content is reduced, and the paper shrinks accordingly.
There is a problem that the so-called curl after copying becomes large and the paper is jammed in the sorter, so that the paper cannot be discharged and the workability deteriorates.

As a method for preventing curling that occurs after transfer, Japanese Patent Publication No. 241024/1990 describes that the top dryer and the bottom dryer in the drying process have different vapor pressures for drying. . Also,
When containing high-yield pulp, the water content in the product is 2.5 to 6.5% and the surface electric resistance is 1.0 × 10 ⁹
Japanese Patent Publication No. 3-41822 discloses a method of preventing curling by setting the value to 1.0 × 10 ¹¹ Ωcm.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to obtain a curl at the time of copying in a conventional electrophotographic transfer paper.

[0012]

According to the present invention, the content of the filler in the paper is 5 to 10% by weight, and the hybrid (Hybri) is used.
d) type paper machine, and the amount of dehydration from the surface is 5
And 20% and the ash distribution in the thickness direction of the transfer paper is 4: 6 to 6: 4 on the front side and the back side.

The ash content in the transfer paper is set to 5 to 10% in order to suppress the generation of paper powder due to the contact between the transfer roll and the conveyor in the copying machine and to obtain the proper surface friction resistance for the transfer of the paper. preferable.

The present invention uses a hybrid paper machine to make a transfer paper, and the amount of dehydration from the surface is 5 to 20% of the total amount of dehydration. If the amount is 20% or more, the ash content on the front side is relatively small.

The amount of dehydration from the surface is 5 to 20% as described above.
It is possible to adjust the ash distribution in the thickness direction of the transfer paper to be 4: 6 to 6: 4 on the front side and the back side by adjusting to, and by reducing the difference between the front side and the back side of the ash distribution, curl change due to humidity change It is possible to obtain a transfer sheet for electrophotography, which has less curl and has a curl of 10 or less at the time of copying in a copying machine.

The surface electric resistance of the transfer paper is also an important factor. When the surface electric resistance becomes high, static electricity is apt to be generated at the time of manufacturing or cutting the transfer paper, and the residual static electricity causes transfer at the time of paper feeding. So-called multi-feeding in which two or more sheets are fed at the same time, defective peeling of the transfer sheet from the photosensitive drum,
Since a large amount of static electricity is charged on the transfer paper surface, copy defects due to partial scattering of toner and stacking defects of the paper discharge tray due to adhesion between transfer paper sheets are likely to occur.

Therefore, the transfer paper is treated with a conductive agent, and the surface electric resistance (JIS P 8111) in the condition of being conditioned at 20 ° C. and relative humidity of 65% (JIS P 8111).
C 2318) is preferably set to a value of 10 ⁹ to 10 ¹¹ Ωcm. Examples of the conductive agent used in the present invention include inorganic salts such as sodium chloride, potassium chloride, sodium aluminate, sodium phosphate, calcium chloride, magnesium chloride, and sodium sulfate, and organic salts such as potassium formate and sodium sodium bromide. Acid salts and surfactants such as soaps, phosphates and carboxylates, and quaternary ammonium salts, polyacrylic acid salts, salts of styrene-maleic acid copolymers, polyelectrolytes such as polystyrene sulfonates, and silica, Inorganic conductive substances such as alumina and montmorillonite can be used, but it is preferable to use an inorganic salt having a low deliquescent property.

The conductive agent can be coated or impregnated with a size press or the like during the papermaking process together with a water-soluble adhesive such as starch, modified starch, polyvinyl alcohol, styrene-butadiene copolymer latex. The type and amount of the conductive agent is 10 ^{9 on} the surface electric resistance of the transfer paper treated with the conductive agent.
It can be selected to fall within the range of -10 ¹¹ Ωcm.

In the present invention, processed starch is wheat, rice,
It is made by oxidizing starch such as tapioca, corn and potato under high temperature and high pressure. Of these exemplified starches, tapioca starch is particularly preferably used. Tapioca can obtain effective coating suitability at a relatively low concentration, has excellent compatibility with the polyamine-polyamide-epichlorohydrin resin, and is unlikely to cause residue or the like even after stirring for a long time. Here, the conditions of high temperature and high pressure are 100 to 150 ° C. and 1 to 5 kg.
/ Cm ² .

The base paper used in the present invention is LBKP, N
Chemical pulp such as BKP, GP, PGW, RMP, TM
Mechanical pulp such as P, CTMP, CMP, CGP, DIP
Pulp such as waste paper pulp can be used, and these can be used alone or in combination as appropriate.

In the present invention, since calcium carbonate is used as a filler for papermaking in a neutral system, a neutral sizing agent is used.
As the neutral sizing agent, alkyl ketene dimer (hereinafter abbreviated as AKD) and alkenyl succinic anhydride (hereinafter abbreviated as ASA) are used because of their excellent size.

A filler may be added to the transfer paper of the present invention for the purpose of improving the flexibility and opacity of the paper. For example, heavy calcium carbonate, light calcium carbonate, talc, kaolin, clay and white carbon. Inorganic pigments such as titanium dioxide, satin white, wax stone clay, and diatomaceous earth.

The transfer paper of the present invention may contain a dye, a fixing agent, a dry paper strength enhancer and the like, which are usually used in papermaking, if necessary.

[0024]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 3 To 100 parts of LBKP beaten to a freeness of 500 ml csf, 1 part of talc as a filler and an additive chemical, 7 parts of light calcium carbonate (TP121, manufactured by Okutama Kogyo Co., Ltd.), alkyl ketene dimer (size) Pine k903, manufactured by Arakawa Chemical Co., Ltd.) was added as an alkyl ketene dimer content in an amount of 0.1 part, and amphoteric starch (Kate 3210, manufactured by Oji National Co., Ltd.) was added, and the stock material was used in a hybrid paper machine (Bel-
Form Mitsubishi Heavy Industries Ltd.), the surface dehydration amount at that time is 5%, 10%, 20% of the total dehydration amount, and the basis weight is 64 g.
A transfer base paper of / m ² was produced. A surface sizing agent prepared by mixing 17 parts of oxidized starch, 0.6 part of sodium chloride and 0.4 part of styrene-acrylic acid copolymer was applied to the surface of the base paper by a size press so as to be 1.2 g / m ^2. A transfer paper having a water content of 5.0% was produced through a machine calendar. The obtained transfer paper was copied by a copying machine and the curl after copying was evaluated. The results are shown in Table 1.

Comparative Example 1 A transfer sheet was prepared in the same manner as in Example 1 except that the surface dehydration amount was 3% and the total dehydration amount was 3%.

Comparative Example 2 A transfer sheet was prepared in the same manner as in Example 1 except that the fourdrinier paper machine was used and no surface dehydration was used.

The results are shown in Table 1.

[0029]

[Table 1]

The curls in the table are as follows. 1. Humidity control curl This shows the curl of a 10 cm square sheet sample at a temperature of 20 ° C. and a humidity of 65%. The lifted dimension of the sheet corner from the sheet plane was measured in mm. Negative values indicate lifted dimensions with the sheet surface facing down. 2. Curl change In the same measurement as the humidity control curl, the curl change amount at 20% and 80% humidity is shown. 3. Heat curl In the same measurement as the humidity control curl, the curl immediately after heating at 105 ° C. for 5 minutes is shown. 4. Copy curl Indicates the curl immediately after copying an A4 size sheet (210 cm x 297 cm) with a copying machine. The lifted dimension of the sheet corner from the sheet plane was measured in mm.

[0031]

INDUSTRIAL APPLICABILITY The transfer paper of the present invention is extremely suitable as a transfer paper for electrophotography because the curl change with humidity change is small and the curl after copying is small as compared with the comparative example.

Claims (1)

[Claims] 1. The content of the filler in the paper is 5 to 10% by weight,
An electronic device characterized in that the amount of dehydration from the surface is 5 to 20% of the total amount of dehydration using a hybrid paper machine, and the ash content distribution in the thickness direction of the transfer paper is 4: 6 to 6: 4 on the front and back sides. Photo transfer paper.