JPH0341822B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to electrophotographic transfer paper used in electrophotographic copying machines, printing machines, computer line printers, and the like. Conventionally, transfer paper for toner image transfer in electrophotography has been characterized by paper runnability, copy quality,
It is necessary to satisfy characteristics that are compatible with electronic copying machines, such as image fixability, and paper generally known as high-quality paper made of 100% chemical pulp has been used as a paper that satisfies these conditions. . In order to reduce the cost of copying, the present inventors focused on paper containing high-yield pulp, so-called medium-quality paper, and conducted research on the application of medium-quality paper to copying machines. By the way, the high-yield pulp mentioned here refers to pulp that is produced with a higher cooking yield than ordinary chemical pulp, and includes ordinary ground pulp (GP),
These include chemical ground pulp (CGP), refined ground pulp (RGP), thermomechanical pulp (TMP), semi-chemical pulp (SCP), etc., but these medium-quality papers have serious drawbacks in their copyability. It turned out that That is, compared to cellulose, high-yield pulp requires
Because it contains a large amount of highly hygroscopic hemicellulose, it has a higher moisture content under the same environment than chemical pulp with a low hemicellulose content. Generally, the moisture content of medium-quality paper is 6.5 to 8.0.
%. When this is used in an electrophotographic copying machine, the amount of moisture evaporated from the heated surface during toner fixation increases, resulting in a large moisture difference between the front and back sides of the paper. Therefore, the curl becomes larger. In addition, paper generally becomes less stiff as its water content increases. The large curl and low stiffness cause paper jams, poor stacking on paper ejection trays, poor sorter (automatic collating machine) performance, and problems with paper alignment after copying, bookbinding, etc. As a means to overcome this drawback, a method of lowering the water content can be considered. This is because, when paper is heated by the toner fixing device of an electrophotographic copying machine, less water evaporates from the heated surface of the paper than paper with a high moisture content, thereby reducing the difference in moisture between the front and back sides of the paper. Regarding the relationship between moisture content and curl, an electrophotographic copying machine Fuji Xerox FX3600 was used to examine Jujo papermaking paper "Piraine" (basis weight 66.3 g/m ² ).
The measured values are shown in Figure 1. Regarding the relationship between moisture content and stiffness, please refer to the electrophotographic copying machine.
Figure measured using the same paper using FX3101
Shown in 2. Figure 3 shows the relationship between the initial moisture content and the evaporated moisture after passing through the fixing device, measured using a Fuji Xerox 3103 machine. However, simply reducing the water content increases the surface electrical resistance of the paper, which causes various troubles when used in an electrophotographic copying machine. For example, due to the high surface electrical resistance, static electricity is easily generated during paper manufacturing and cutting processing, and it also tends to remain. and defective separation of the paper from the photosensitive belt, poor copy quality due to local scattering of toner (toner explosion) due to the large amount of static electricity charged on the paper surface, and poor copy quality due to the large amount of static electricity remaining between the sheets. Examples include poor stacking of paper on the paper ejection tray due to adhesion and electric shock due to contact with the human body when paper is ejected. Conventionally, there has been a preconceived notion that medium-quality paper has a high moisture content and is easy to absorb moisture, and there has generally been no attempt to add a hygroscopic conductive agent to it or to lower the moisture content. According to the present invention, the paper contains high-yield pulp and a conductive agent in an amount of 20% or more of the total amount of paper pulp, and has a moisture content of 2.5 to 6.5% at the time of product,
Surface electrical resistance under JIS P8111 measurement conditions is 1.0
An electrophotographic transfer paper having a resistance of ×10 ⁹ to 1.0 × 10 ¹¹ Ωcm has been provided, and by using this electrophotographic transfer paper, it has been succeeded in imparting suitability to medium-quality paper as a transfer paper for an electrophotographic copying machine. For example, in the papermaking process, sodium chloride and starch are mixed with general medium-quality paper and the surface is coated with 0.05 to 0.1 g/ ^m2 (sodium chloride only) on both sides to reduce the moisture content to 2.5 to 6.5%. obtained by The content mentioned here is
Means surface coating, internal addition, impregnation, etc. The paper of the present invention obtained by the above process has a higher stiffness due to the lower moisture content, and also reduces curling of the paper after fixing, so paper feed in an electrophotographic copying machine is improved. Improves aptitude. In addition, the increase in surface electrical resistance of paper caused by lowering the product moisture content is suppressed by the inclusion of a conductive agent, resulting in the aforementioned double feeding, poor peeling from the photoreceptor, poor copy quality, poor paper output tray stacking, and paper residue. There are no problems such as electric shock to the human body due to static electricity. Therefore, the high frequency pulp-containing paper of the present invention has much better paper feedability in an electrophotographic copying machine than conventional medium-quality paper. The conductive agents used in the present invention include inorganic salts such as sodium chloride, potassium chloride, lithium chloride, sodium aluminate, sodium phosphate, calcium chloride, magnesium chloride, and sodium sulfate, and organic salts such as potassium formate and sodium bromate. acid salts, and surfactants such as soaps, phosphates, and carboxylates; and polymer electrolytes such as quaternary ammonium salts, polyacrylates, salts of styrene-maleic acid copolymers, polystyrene sulfonates, and silica. Any material that can enhance the electrical conductivity of paper, such as inorganic conductive materials such as , alumina, and montmorionite, may be used. Paper treated with these conductive agents is
Surface electrical resistance at 20℃ and 65% relative humidity (as specified by JIS P8111) is 1.0×10 ⁹
It shows a value of ~1.0×10 ¹¹ Ω. Therefore, the type and amount of the conductive agent to be added can be selected so that the surface electrical resistance value of the treated paper falls within the above-mentioned range. In addition, after the paper was pretreated according to JIS-P-8111, the surface electrical resistance was JIS-C-2318, and the water content was
The stiffness was measured according to JIS-P-8127 and JIS-P-8143. Also, high yield pulp, especially GP,
Medium-quality paper containing RGP and TMP has higher opacity than high-quality paper made only of chemical pulp. Therefore, when copying on both sides of PPC paper, there will be no set-off, the copied image will be easy to read, and when the copied original is used as an original, the image on the top page will not be copied, and the platen There are advantages such as dirt not being copied. (Basic weight 64-67
GP30% when comparing opacity with g/ ^m2 paper
The opacity is 88-92% for medium-quality paper and 81% for high-quality paper.
~84%; Opacity measurement method: JIS P-
8138). The paper of the present invention can be used for purposes other than electrophotographic copying paper, such as printing machines and computer line printers. The paper of the present invention has lower moisture content and less residual static electricity than conventional medium-quality paper, so it is easier to align and bind books after printing, and it can also be used as continuous slip paper for computer line printers. Feedability and paper alignment have been improved and it can be used for a wide range of applications. Furthermore, when the content of high-yield pulp is 20% or more of the total amount of pulp in the paper, it is extremely advantageous in terms of manufacturing costs. The present invention will be explained below with reference to Examples. Example 1 For medium-quality paper with a basis weight of 66.3 g/ ^m2 and a pulp composition of 20% NBKP, 50% LBKP, and 30% RGP (refined ground pulp) as shown in sample number 1 in Table 1, the size during the paper making process 5.0% by weight of starch and 0.3% by weight of potassium chloride were applied to the surface using a press, and the liquid coating amount was 1.2g/m ² of starch in terms of solid content.
Paper containing 0.07 g/m ² of potassium chloride and a final moisture content of 4.5% was prepared. Table 3 shows the results of testing the physical properties and runnability of this paper. Example 2 Table 3 shows the results of testing the physical properties and runnability of paper made in the same manner as in Example 1 using the recipe of sample number 2 in Table 1 so that the water content was 3.5%.
Shown below. Example 3 Table 1 shows the results of testing the physical properties and running characteristics of paper prepared in the same manner as in Example 1 using the recipe of sample number 3 in Table 1 so that the moisture content was 5.5%.
Shown in 3. Comparative Example 1 Medium-quality paper with a basis weight of 66.3 g/m ² and a pulp composition of 5% NBKP, 65% LBKP, 25% CGP (chemical ground pulp), and 5% GP (ground pulp) as shown in sample number 1 in Table 2. In this paper, 5.0% by weight of starch was coated on the surface using a size press during the papermaking process, and paper with a liquid coating amount of 1.2 g/m ² in terms of solid content was prepared. Table 3 shows the results of testing the physical properties and running properties of this paper. Comparative Example 2 Table 3 shows the test results of the physical properties and running characteristics of paper prepared in the same manner as Comparative Example 1 using the recipe of Sample No. 2 in Table 2. Comparative Example 3 Table 3 shows the test results of the physical properties and running characteristics of paper prepared in the same manner as Comparative Example 1 using the recipe of sample number 3 in Table 2.

【table】

【table】

【table】

【table】 [Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between moisture content in transfer paper and curl, Figure 2 is a graph showing the relationship between moisture content in transfer paper and stiffness, and Figure 3 is a graph showing the relationship between moisture content in transfer paper and stiffness. It is a graph showing the relationship between time and evaporated moisture.

Claims (1)

[Claims] 1 Contains high-yield pulp and a conductive agent that accounts for 20% or more of the total amount of paper pulp, and reduces the moisture content in the product.
2.5 to 6.5%, and the surface electrical resistance under the measurement conditions of JIS P8111 is 1.0×10 ⁹ to 1.0×
Electrophotographic transfer paper that is ^10-11 Ωcm.