JPH0241024B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to transfer paper used for electrostatic copying, particularly when the moisture content during use is 4 to 9 (%).
The present invention relates to a transfer paper having excellent copying machine runnability and image characteristics within the range of . In recent years, as electrostatic copying machines have become faster and the rate of use of sorters for sorting copied sheets has also increased, the quality required of the transfer paper used in these machines has also increased year by year. However, conventional transfer paper has the following problems. That is, when the package of transfer paper is opened, the paper absorbs moisture, and when the paper is heated during the fixing process in the copying machine, the paper curls significantly toward the non-heated side. This causes the paper to jam in the conveyance means or sorter section after the fixing process. In particular, with copying machines that use a heat roll type fixing device, the necessary amount of heat is directly transferred to the transfer paper in a short period of time, which causes the paper to curl significantly.
As a result, there were many problems with paper jams.
In order to improve this problem, it is possible to take measures such as keeping the moisture content of the transfer paper below 4.0%, or increasing the basis weight of the paper to 127.9 g/ ^m2 or more, for example. When paper absorbs moisture,
The paper becomes wrinkled, wavy, poorly fixed, or paper jams occur because the paper is too stiff, making it unsuitable for transfer paper. This invention was made in view of such circumstances,
By providing a transfer paper that has excellent copying machine runnability and image characteristics when the moisture content during use is in the range of 4 to 9%, it can also be used in an electrostatic copying machine with a heat roll type fixing device. This prevents paper jams from occurring after the fixing process or in the sorter section. The present invention will be described in detail below with reference to the drawings. As shown in FIG. When the transferred paper (hereinafter simply referred to as paper) 3 passes between the rolls 2 and 2, the paper 3
The side surface of the heat roll 1 (hereinafter referred to as the W surface) receives the heat of the heat roll 1 and dries and shrinks, resulting in curling of the paper 3 with the W surface inside.
The W surface of the paper 3 has less moisture than the side surface of the pressure roll 2 (hereinafter referred to as the F surface), and a moisture gradient occurs within the paper 3. Next, when the paper 3 passes between the heat roll 1 and the pressure roll 2, moisture moves within the paper 3 from the F side to the W side, so the F side also contracts and the amount of curl on the W side of the paper 3 decreases. It gradually decreases. At this time, if the moisture content of the paper 3 before heating is low, the moisture gradient after heating with the heat roll 1 is small and the shrinkage of the F side is also small, so the curl after heating is still maintained with the W side inside. (Figure 2b). However, if the moisture content before heating is high, the shrinkage of the F side will also be large, so the curl after heating will be the W side curl (Figure 2 a).
From there, the curve shifts to the F-plane curl, that is, the curl with the F-plane inside (Fig. 2c). This is the curl on the non-heated side that occurs in conventional transfer paper when the moisture content is 4.0 (%) or more. On the other hand, in this invention, by utilizing the two-sided nature of the moisture content of the paper 3, when the moisture content is high, the curl after heating of the paper 3 is small, and the heating side, that is, the W side is set as the inner side. This paper is designed to maintain its curl, and is especially suitable for use as transfer paper for electrostatic copying, with a moisture content of 5.5 at the time of papermaking.
~6.5%, when tested using the curl test method described below, the degree of curl is 0 to +13 (0 = no curl, + = curled toward the heated side)
This was made based on the discovery that a material having the following curling properties is suitable. That is, the inventors considered the following two points as a method for manufacturing paper with reduced curl on the non-heated side when the moisture content is 4.0 (%) or more. () Reduce the shrinkage of the non-heated surface due to the movement of moisture from the non-heated surface to the heated surface due to heating. () Increase the curl of the heated surface due to heating. In addition, in order to realize the former method, the two-sided nature of the paper is used to create a paper structure that reduces shrinkage on the non-heated side, and in order to realize the latter method, the following two methods are used. I devised it. (1) During the drying stage during papermaking, the top dryers 4a, 5a and bottom dryer 4b of the second dryer group 4 and after dryer 5 shown in FIG.
Make a difference in the vapor pressure of 5b. That is, the vapor pressure of the bottom dryers 4b and 5b is increased to apply dry compressive stress to the W surface. Then, this internal stress is released by heating during copying to obtain a large curl on the heated side. (2) A method of increasing the length of fibers and the distribution of filler on the front and back sides of paper by adjusting the dewatering speed with paper machine wire. The effects of the above two methods can be further enhanced by further beating the raw material pulp used. Furthermore, when the transfer paper obtained according to the present invention is used in an electrostatic copying machine, the moisture content during use is within the range of 4 to 9 (%). characteristics) will be excellent. Next, the curl testing method and curl testing device used for the transfer paper of the present invention will be explained with reference to FIG. The roll 1' is constructed by coating the surface of a metal core 9 with a Teflon (trade name) layer 10, and has a quartz lamp installed therein as a heater 11. The power supplied to this heater 11 is
The surface temperature of the heat roll 1' is always maintained constant by being controlled by a signal from a temperature detector (not shown) such as a thermister provided near the surface of the heat roll 1'. The pressure roll 2' has a structure in which a thick rubber layer 13 is provided around the metal core 12, and the surface of the rubber layer 13 is covered with a Teflon layer 14. They are pressed together under a constant pressure, and at this time, the rubber layer 13 on a part of the surface of the pressure roll 2' is deformed by the pressure to form a contact arc (contact arc length) with a constant width. The curl test device actually used had a heat roll 1′ with a diameter of 76φ, a length of 35mm, and a circumferential speed of 500.
mm/sec, surface temperature 185±3℃. The pressure roll 2' has a diameter of 76φ, a length of 350mm, and a circumferential speed of 500mm/sec, and the pressure is adjusted so that the contact arc is 13±1mm.The method for measuring the degree of curl is as described in "J. The transfer paper 3 of the present invention is first passed between the heat roll 1' and the pressure roll 2' of the curl test device shown in Fig. 4. Immediately after curling the paper 3, the center of one side perpendicular to the curl axis is suspended using a test paper suspension device 15 with a width of about 1 cm as shown in FIG. 5, and a glass for measuring the curl radius is placed underneath. The curl radius (cm) is visually measured using the scale 16a of the gauge 16. Then, the degree of curl of the test paper 3' is calculated using the following equation. Curl degree = 1/R x 100 R: Curl radius (cm) Next, the test paper 3' is turned upside down and hung again from the hanging device 15, and the curl degree of the opposite side is measured in the same manner. The above measurement was repeated twice for one sheet of test paper 3', and the larger measured value was taken as the curl degree of that test paper 3'. Further, if the test paper 3' was curled toward the heated side, it was considered curled, and if it was curled on the opposite side, it was considered curled, and the above test method was carried out on the transfer papers obtained in the following Examples and Comparative Examples. Example 1 Pulp (freeness 450 CSF) with a blending ratio of hardwood bleached kraft pulp (LBKP)/softwood bleached kraft pulp (NBKP) = 80/20 (weight), talc 10% by weight, banded sulfate 1% by weight, and rosin size After adding 0.2% by weight of the agent, transfer papers with basis weights of 52.3 g/m ² , 64.0 g/m ² and 81.4 g/m ² were made using a fourdrinier multi-tube paper machine at a paper speed of 500 m/min, and then passed through a decurler. Then I adjusted the curl. Further, the drying conditions of the dryer at this time are as follows. Dryer 2nd group: Top dryer steam pressure
0.70Kg/cm ² :Bottom dryer steam pressure
1.30Kg/cm ² After dryer: Top dryer steam pressure
0.50Kg/cm ² :Bottom dryer steam pressure
0.70Kg/cm ² 10 A4 size sheets of transfer paper 3 obtained by the above method were vertically cut, and the moisture content was 5.5 to 6.5 (%).
A test paper 3' was prepared by pre-processing with an appropriate chamber or the like so that the result was as follows. A curl test was carried out by passing 10 sheets of the test paper in the above-mentioned curl test device in the horizontal direction, that is, in such a way that the horizontal direction of the paper was perpendicular to the axis of the heat roll 1' of the device.
The results shown in Table 1 below were obtained. The degree of curl in this table is the average value of the degree of curl of 10 sheets of test paper converted into an integer according to JIS Z 8401 (rounding of numerical values).

[Table] Example 2 10% by weight of clay, 1% by weight of band sulfate and pulp (freeness 400CSF) having a blending ratio of bleached hardwood kraft pulp (LBKP)/bleached softwood kraft pulp (NBKP) = 80/20 (weight) After adding 0.2% by weight of rosin sizing agent, transfer papers with basis weights of 52.3 g/m ² , 64.0 g/m ² and 81.4 g/m ² were made using a Fourdrinier multi-tube paper machine at a speed of 500 m/min, and then transferred to a decurler. I went through the curl adjustment process. Further, the drying conditions of the dryer at this time were the same as in Example 1 above. When the transfer paper obtained by the above method was subjected to a curl test in the same manner as in Example 1, the results shown in Table 2 below were obtained.

[Table] Example 3 10% by weight of clay and 1% by weight of sulfuric acid in pulp (freeness 350 CSF) with a blending ratio of hardwood bleached kraft pulp (LBKP)/softwood bleached kraft pulp (NBKP) = 80/20 (weight) and 0.2% by weight of rosin sizing agent, and transfer papers with basis weights of 52.3 g/m ² , 64.0 g/m ² and 81.4 g/m ² were made using a fourdrinier multi-tube paper machine at a paper speed of 500 m/min, and then decurled. I went through it to adjust the curl. Further, the drying conditions in the dryer at this time were the same as in Example 1. When the transfer paper obtained by the above method was subjected to a curl test in the same manner as in Example 1, the results shown in Table 3 below were obtained.

[Table] Comparative Example 1 10% by weight of talc, 1% by weight of bandate sulfate, and rosin sizing agent in pulp (freeness 450CSF) with a blending ratio of LBKP/NBKP = 80/20 (weight)
Add 0.2% by weight and make the paper at high speed using a Fourdrinier multi-tube paper machine.
Basis weight 52.3g/m ² , 64.0g/m ² and 81.4 at 500m/min
After making a transfer paper of g/m ² , it was passed through a decurler to adjust the curl. The drying conditions at this time were as follows. Dryer 2nd group: Top dryer steam pressure
1.30Kg/cm ² :Bottom dryer steam pressure
1.30Kg/cm ² After dryer: Top dryer steam pressure
0.70Kg/cm ² :Bottom dryer steam pressure
0.70Kg/cm ² The transfer paper obtained by the above method was cut vertically into 10 A4 size sheets, and the moisture content was 5.5 to 6.5 (%).
A test paper 3' was prepared by pre-processing with an appropriate chamber or the like so that the result was as follows. When a curl test was conducted by passing 10 sheets of the test paper in the lateral direction through the above-mentioned curl test device, the results shown in Table 4 below were obtained. The degree of curl in this table is the average value of the degree of curl of 10 sheets of test paper.
It is shown as an integer according to JIS Z 8401 (how to round numbers).

[Table] Comparative Example 2 10% by weight of clay, 1% by weight of aluminum sulfate, and rosin sizing agent in pulp (freeness 400CSF) with a blending ratio of LBKP/NBKP = 80/20 (weight)
Add 0.2% by weight and make the paper at high speed using a Fourdrinier multi-tube paper machine.
Basis weight 52.3g/m ² , 64.0g/m ² and 81.4 at 500m/min
After making a transfer paper of g/m ² , it was passed through a decurler to adjust the curl. Note that the drying conditions of the dryer at this time were the same as in Comparative Example 1. The transfer paper obtained by the above method was subjected to a curl test in the same manner as in Comparative Example 1, and the results are shown in Table-5 below.
The following results were obtained.

[Table] Comparative Example 3 10% by weight of clay, 1% by weight of aluminum sulfate, and rosin sizing agent in pulp (freeness 350CSF) with a blending ratio of LBKP/NBKP = 80/20 (weight)
Add 0.2% by weight and make the paper at high speed using a Fourdrinier multi-tube paper machine.
Basis weight 52.3g/m ² , 64.0g/m ² and 81.4 at 500m/min
After making a transfer paper of g/m ² , it was passed through a decurler to adjust the curl. Note that the drying conditions of the dryer at this time were the same as in Comparative Example 1. When the transfer paper obtained by the above method was subjected to a curl test in the same manner as in Comparative Example 1, the results shown in Table 6 below were obtained.

[Table] Next, transfer sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 above were cut into A4 size sheets.
Cut 1,000 sheets vertically, pre-process them in an appropriate chamber, etc. so that the moisture content is 4.0 (%) and 9.0 (%), which are the lower and upper limits of the moisture content during use, and use it as a test paper. When a copying machine running test was conducted using a copying machine (Fuji Xerox 9200B), the results shown in Table 7 below were obtained. Also, 〇 in this diagram,
Explanations of the states of △ and × are shown in Table-8, and Table-8
According to the test results in step 7, if the degree of curl is in the range of 0 to +13 when tested with a curl tester, there will be almost no paper jams after the fixing process when used in a high-speed electrostatic copying machine, and there will be no paper jams in the paper output tray or paper output tray. It was confirmed that it has excellent accommodability in a sorter.

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【table】 [Brief explanation of the drawing]

FIGS. 1 and 2 a to d are explanatory diagrams showing how the transfer paper curls after the fixing process, FIG. 3 is an explanatory diagram showing the drying process during papermaking, and FIG. 4 is an explanatory diagram of the curl test device. FIG. 5 is an explanatory diagram of the curl test method.

Claims (1)

[Claims] 1 The degree of curl when tested by the curl test method when the moisture content is 5.5 to 6.5 (%) is 0 to +
Transfer paper characterized by being in the range of 13.