JPH03287894A - Transfer paper for electrophotography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic transfer paper, and more particularly, the present invention relates to a transfer paper used in an electrophotographic copying machine that thermally fixes toner. This invention relates to a transfer paper that has good runnability and workability in a copying machine.

[Prior Art] Transfer paper used in electrophotographic copying machines is required to have good runnability and workability in the copying machine, and in particular to minimize curling that occurs after toner is transferred.

In electrophotographic copying machines, a crosspiece is used in which an image is formed on transfer paper using toner and then heated and pressed in order to fix the toner on the paper, and this temperature is usually 180° C. or higher. That is, after image formation with toner, the transfer paper is passed under pressure between a metal roll heated to a high temperature and an elastic roll. At this time, the transfer paper containing recycled paper pulp will curl due to a complicated mechanism such as drying and shrinkage due to heating and pressure, especially if the transfer paper is stored for a long time in a high humidity environment before copying. When the moisture content of the transfer paper increases,
There has been a problem in that the degree of curling after copying increases, making copying impossible.

Furthermore, conventionally, virgin pulp, mainly bleached hardwood pulp, has been mainly used as a raw material for transfer paper for electrophotographic copying machines due to its runnability and workability in copying machines, but in recent years, especially due to social demands, virgin pulp has been mainly used. As a result, recycled pulp from used paper such as newsprint and miscellaneous paper has come to be mixed and used as a raw material. However, when recycled newspaper pulp containing mechanical pulp is blended, the equilibrium moisture content corresponding to the relative humidity of the transfer paper is higher than that of virgin pulp that does not contain mechanical pulp, so the transfer paper There is a problem in that the curl after copying increases, further aggravating the problem that copying is impossible.

[Problems to be Solved by the Invention] In view of the current situation, the inventor of the present invention conducted intensive research on the mechanism of curl generation in copying machines, and as a result, discovered the existence of the following three phenomena as the mechanism of curl generation. One of these is curling due to dryness due to the difference in expansion/contraction ratio between the front and back sides of the transfer paper, and the second is curling due to the ironing effect of a heating roll. That is, the curvature toward the heat fixing roll due to heating, the heat fixing roll (heat roll), and the rubber backup roll causes curling toward the side where the toner is fixed. The third curl generation mechanism is related to the moisture content of the transfer paper; heating by the heat fixing roll rapidly reduces the moisture content on the heated surface side, creating a moisture gradient in the thickness direction of the transfer paper.

After heating and fixing, this moisture gradient becomes uniform relatively quickly, and the transfer paper "curls with the last dry side inward."
Due to the characteristics based on the viscoelasticity of the paper, the paper curls with the side opposite to the one where the toner is fixed facing inward. The curl caused by this third mechanism becomes smaller as the moisture content of the transfer paper before copying is lowered, and even with transfer paper containing recycled paper pulp, if the moisture content is kept below 8.3%, curling will occur during copying. The inventors have discovered that no trouble occurs and have completed the present invention.

Therefore, an object of the present invention is to provide a transfer paper containing recycled paper pulp that exhibits minimal curl after copying in an electrophotographic copying machine even if it is left in high humidity for a long period of time, and has extremely good runnability and workability. Our goal is to provide the following. Note that the transfer paper includes not only sheet paper but also continuous slip paper.

[Means for Solving the Problems] The present invention contains recycled pulp of used paper, and the temperature is 20°C, relative temperature 6.
This electrophotographic transfer paper is characterized in that the equilibrium moisture content from the moisture absorption side at 5% is 8.3% or less.

Although there is no particular restriction on the method of reducing the equilibrium moisture content of the transfer paper from the moisture absorption side to 8.3% or less at 20°C and relative humidity of 65% for the purpose of the present invention, the first method for realizing this invention is to reduce the equilibrium moisture content to 8.3% or less. When using recycled newspaper pulp with a high moisture content, the amount of recycled high quality recycled paper pulp with a relatively low equilibrium moisture content should be adjusted.

The second method is to increase the freeness of the virgin pulp to levels higher than those normally used. The inventor, for example,
The freeness of bleached hardwood pulp is varied from 450 mff (Canadian standard freeness, C, S, F,) to 500 mj2 (
It was found that when C, S, F, and l were used, the equilibrium moisture content of paper at 20° C. and relative humidity of 65% was lowered by 0.3%.

The third method is to use dried pulp as virgin pulp, for example, the equilibrium moisture content of undried pulp at 20°C and 65% relative humidity is 8.6%, while the equilibrium moisture content of dry pulp is 8.6%. 1%, and the shoe dry pulp is lower by about 0.5%. The dried pulp for the present invention is used by evaporating the moisture contained in the pulp using a steam dryer, and is appropriately selected from pulps with a moisture content of 5 to 50%. It is more convenient to reduce the equilibrium moisture content of paper.

The fourth method is to treat waste paper recycled pulp with alkali in the deinking process of waste paper, and the present inventor has found that by treating waste newspaper with alkali, part of the lignin in the mechanical pulp is removed, and It has been found that the equilibrium moisture content of paper at a humidity of 65% decreases by approximately 0.5%.

By using the above-mentioned methods alone or in combination, it is possible to produce waste paper recycled pulp that has an equilibrium moisture content of 83% or less from the endothermic side at 20°C and a relative temperature of 65%, and has good runnability and workability in copying machines. Transfer paper for an electrophotographic copying machine can be obtained.

The raw material pulp used in the present invention includes bleached hardwood pulp, bleached softwood pulp, deinked waste paper pulp, or a mixed pulp of these pulps, and may be used as desired.

Furthermore, the present invention is applicable to electrophotographic transfer paper manufactured using known papermaking chemicals and papermaking machines.

[Example 1] The present invention will be described in more detail with reference to Examples below, but of course the present invention is not limited thereto.

Example 1 Freeness 400 +n! as pulp raw material 2 (Canadian Standard Freeness, C, S, F) hardwood bleached pulp (
LBKP) and deinked Freeness 200 m12 (C
,S.

F. ) used newspaper pulp and freeness 350 m12
(C, S, F,) high quality waste paper pulp 20:40:4
It was used in a weight ratio of 0. To this raw material, the following paper-making chemicals and fillers were added in absolute dry amounts per pulp to prepare a paper stock.

Alkenyl succinic anhydride 0.09% by weight (Fiberan 81, manufactured by Tamago National Co., Ltd.) Cationized starch 0.5% by weight (Kate F, manufactured by Tamago National Co., Ltd.) Sulfuric acid band 0.2% by weight Light calcium carbonate 5.0 Weight% (TP-12
1S, manufactured by Okutama Kogyo Co., Ltd.) This paper stock was used to make paper using a fourdrinier paper machine, passed through a size press and a machine calender, to a paper weight of 64 g/m2. A transfer paper with a density of 0.7 g/cm'' and paper moisture of 5.0% was obtained.

As size press chemicals, size press starch (vitified starch, Tamago Ace B, manufactured by Tamago Cornstarch Co., Ltd.) and styrene maleic acid copolymer (Polymalon 385, manufactured by Arayo Kagaku Co., Ltd.) were used in a ratio of 5:G, 2. The coating of this mixture on paper was 0.6 g/m2. The resulting transfer paper (A4
After conditioning the humidity at 20° C. and 65% RH for 12 hours, curling, runnability, and workability in a copying machine were evaluated.

(Evaluation method of transfer paper) To evaluate the runnability and workability of transfer paper in a copying machine, 1000 sheets of A4 size transfer paper were copied using a Fuji Xerox electrophotographic copying machine (model = 5990, with sorter). It was done.

(1) Curling As shown in Figure 1, pick up one side of the curled transfer paper with your hand, read the height (L) of the arc on the opposite side, and calculate the average value of the readings of 10 sheets of transfer paper. Ta. The greater the height of the arc, the greater the curl.

(2) Runnability Shown as the number of times troubles such as paper jams occurred while copying 1000 sheets of transfer paper.

(3) Workability The evaluation was based on the number of sheets of transfer paper that entered the sorting turbine after copying.

Example 2 Freeness 520 tn12 fc, s, F as raw material
) Undried LBKP and deinked Freeness 2 (10 m
12 fc, s.

F) IFV dark waste paper pulp was mixed and used in a weight ratio of 40:60. Other paper making conditions are actually 11! ii Same as Example 1.

Example 3 Freeness 550 m12 (C, S, F,
) dry LBKP (Cenibra Pulb, manufactured by Cellulose Ichipo Brasileira, Brazil, moisture 12%) and deinked freeness 200 m12 fc, s, f, ) waste newspaper pulp in a weight ratio of 40.60. It was used as Other paper-making conditions are the same as in Example 1.

Example 4 After dust removal treatment of used newspaper pulp disintegrated with a high-concentration pulper, the pulp was diluted to a pulp concentration of 25%, and 4% of caustic soda (as NaOH) was added to the pulp by weight, and after stirring for 25 minutes, normal After deinking, this used newspaper pulp and freeness 450 m12 fc, s,
A raw material was prepared by blending undried t#LBKP of F and 1 in a weight ratio of 80:20. Other paper-making conditions are the same as in Example 1.

Comparative Example 1 Freeness 400 nu fc, s, as pulp raw material
F,) LBKP and deinked freeness 200 m1
2 tc.

S, F, l newspaper pulp 20: III (
It was used by blending it in a weight ratio of 1. Other paper-making conditions are the same as in Example 1.

Comparative Example 2 The pulp used in Comparative Example 1 as a pulp raw material was changed to 3.
A paper having a weight ratio of 0 to 0 was used, and other paper making conditions were the same as in Example 1.

Table 1 shows the evaluation results of the transfer papers obtained in Examples 1 to 4 and Comparative Examples 1 to 2.

(Margin below) Table 1 As is clear from Table 1, the curling, runnability, and workability after copying of the transfer paper having the characteristic values of the present invention are good, whereas the characteristic values of the present invention are good. It can be seen that the curling, runnability, and workability after copying of the transfer paper without this were inferior.

[Effect of the invention 1] The present invention adjusts the equilibrium moisture content of electrophotographic transfer paper at a certain relative humidity, so that the curl after copying of the transfer paper that has been conditioned at high humidity for a long time is small, and the runnability is improved. This has the effect of significantly improving workability.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing curl measurement after copying of A4 size transfer paper. The curl is indicated by the average value of the measured values of L (mm). 1...L (height of arc) 1 figure

Claims (1)

[Claims] An electrophotographic transfer paper containing recycled recycled pulp and having an equilibrium moisture content from the moisture absorption side of 8.3% or less at 20° C. and relative humidity of 65%.