JPH10254163A - Electrophotographic transparent transfer paper and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain electrophotographic transparent transfer paper using highly beaten pulp, having high transparency and less liable to cause cracking after heat printing in an electrophotographic copying machine. SOLUTION: Pulp beaten to 50-100ml Canadian modified freeness is made paper to obtain the objective transfer paper having >=22gf tear strength (JIS P8116). The Canadian modified freeness is measured by sampling the pulp by 0.5g oven-dry weight and using a plain fabric-shaped bronze wire of 80 mesh in place of a sieve plate. The other conditions are in accordance with Canadian standard form stipulated by JIS P8121. A pulp slurry before the beating is heated to 30-40 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent transfer paper for electrophotography obtained by using a pulp which has been subjected to a high degree of beating treatment and which has undergone extremely fibrillation. The present invention relates to a transparent transfer paper for electrophotography which has few cracks after heating and printing, and a method for producing the same.

[0002]

2. Description of the Related Art For the purpose of obtaining a transparent transfer paper having a natural surface property, a transparent transfer paper is manufactured using pulp which has been extremely fibrillated by viscous beating. Transparent transfer paper, which has been used as the second original drawing for tracing and positive images on drafting screens, has also been used as a transparent transfer paper for electrophotography with the recent improvement in electrophotographic copying machines and printers. Heating and printing by copiers and printers are increasing.

[0005] Along with this, a problem which cannot be considered conventionally has come to occur. One of them is a problem of cracking after heating printing. This is a problem that the edges of the transparent transfer paper for electrophotography are torn or chipped when the edges of the transparent transfer paper for electrophotography after heating printing are aligned or rolled.

[0004] Cracking after heating printing is caused by a reduction in pulp fiber strength due to the extreme progress of fibrillation of pulp in order to obtain high transparency. In order to solve this problem, it is necessary to mix pulp with extremely advanced fibrillation to increase transparency and pulp with a certain level of pulp fiber strength to improve cracking after heating printing. Although various beating conditions are being studied, appropriate effect conditions have not yet been obtained.

[0005] As described above, in the production of transparent transfer paper for electrophotography, it is difficult to adjust to appropriate beating conditions, and the transparent transfer paper for electrophotography which satisfies cracks after heating and printing while maintaining transparency. Is currently not available.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic transparent transfer paper which has excellent transparency and is less likely to crack after being heated and printed by an electrophotographic copying machine or printer.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have come to invent the transparent transfer paper for electrophotography of the present invention and a method for producing the same.

That is, the transparent transfer paper for electrophotography of the present invention comprises:
Modified Canadian freeness (value measured in accordance with JIS P8121 Canadian standard type except that pulp was sampled in an absolutely dry state and 0.5 g of pulp was collected and the sieving plate was made of 80-mesh plain woven bronze wire) was 50 ml or more and 100 ml or more. A transparent transfer paper for electrophotography obtained by forming a beaten pulp below,
The transparent transfer paper for electrophotography has a tear strength of 22 gf or more.

The method for producing a transparent transfer paper for electrophotography according to the present invention is characterized in that the temperature of the pulp slurry before beating the pulp as a raw material is raised to 30 to 40 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the transparent transfer paper for electrophotography of the present invention and a method for producing the same will be described in detail.

In the present invention, it is first found that the tear strength of the electrophotographic transparent transfer paper needs to be 22 gf or more in order to satisfy the cracks of the electrophotographic transparent transfer paper after heating and printing. Was.

Further, the present invention has found that the pulp must have a Canadian modified freeness of not more than 100 ml in order to obtain the transparency required for the electrophotographic transparent transfer paper. However, Canadian anomalous freeness is 50m
If it is less than 1, the fibrillation proceeds too much, and the pulp fiber is distorted, preventing shrinkage during drying and conversely lowering the transparency. As a result, the Canadian modified freeness is 50-100ml.
High clarity can be obtained by beating pulp in the range of

Under the current beating conditions, even in the upper limit of 100 ml of the Canadian modified freeness for obtaining the transparency required for the electrophotographic transparent transfer paper, it is necessary to satisfy cracks after heating and printing. The tear strength does not reach 22 gf.

Further, as a result of intensive studies, the present inventors have found that, as a method for producing a transparent transfer paper for electrophotography according to the present invention, the pulp slurry temperature before beating the pulp is set at 30 to 40 ° C. to obtain an excellent electrophotography. It has been found that transparent transfer paper can be obtained. That is, by raising the pulp slurry temperature to suppress the swelling of the pulp fibers, and by beating under these conditions, it is possible to mix pulp fibers with extremely advanced fibrillation and pulp fibers that have maintained a certain degree of fiber strength. It was successful.

In the method for producing a transparent transfer paper for electrophotography according to the present invention, when the temperature of the pulp slurry is increased,
-40 ° C. Here, if the pulp slurry temperature before beating the pulp is less than 30 ° C., the tear strength of the transparent transfer paper for electrophotography becomes less than 22 gf, and cracks occur after heating and printing. If the pulp slurry temperature before beating the pulp is higher than 40 ° C.,
Pulp fiber length after beating is too low, tear strength is 2
It is less than 2 gf, and cracks occur after printing by heating.

The transparent transfer paper for electrophotography in the present invention includes electrophotographic copying machines, page printers, and the like.
It is used as a recording material for continuous printers, facsimile machines, full-color copiers and the like to which this method is applied.

The pulp used for the transparent transfer paper for electrophotography of the present invention includes NBKP, LBKP, NBSP and LBP.
BSP and the like. In use, they are mixed in proportions according to several purposes.

The pulp in the present invention is beaten by a beater such as a double disc refiner, deluxe finer, Jordan and the like, and then is made.

The pulp used for obtaining the transparency required for the electrophotographic transparent transfer paper of the present invention is actually lower than the measurable minimum value in the Canadian standard freeness test method and cannot be measured. The area has been highly beaten. Therefore, as a means of measuring the freeness of pulp beaten to an area where it cannot be measured by the Canadian standard freeness test method, 0.5 g of pulp is sampled by absolute drying, and the sieving plate is made of a 80-mesh plain-woven bronze wire. JIS P812 except for
The freeness of the pulp was measured by the Canadian modified freeness test method, which is measured according to Canadian standard form No. 1.

In the case of making paper using the beaten pulp in the present invention, a paper machine such as a long net, a round net, a twin wire, an on-top or a hybrid can be used.

[0021]

The present invention will be described below in detail with reference to examples. The present invention is not limited to the embodiments. All parts and percentages in the following are by weight. Further, the value indicating the coating amount is the weight after drying unless otherwise specified.

Example 1 (Used pulp) Softwood bleached kraft pulp (N
Steam was blown into the pulp slurry obtained by disintegrating BKP) at a concentration of 3%, and the temperature was raised to 28 ° C. Thereafter, the pulp was beaten using a double disc refiner and a deluxe finaler (both made by Aikawa Tekko) until the Canadian modified freeness of the pulp became 100 ml. After that, by the fourdrinier paper machine,
A transparent transfer paper for electrophotography of 5 g / m ² was produced. In a size press, a styrene-acryl copolymer (Harima KN500 manufactured by Harima Kasei Co., Ltd.) is coated at 0.1 g / m ² , and then machine calendered to a density of 1.0 g / cm ^3. Was done.

Example 2 In Example 1, the pulp had a Canadian freeness of 80 m.
Except for changing to l, a transparent transfer paper for electrophotography was obtained in the same manner.

Example 3 In Example 1, the pulp was changed to a Canadian freeness of 60 m.
Except for changing to l, a transparent transfer paper for electrophotography was obtained in the same manner.

Example 4 In Example 1, the pulp was changed to a Canadian freeness of 50 m.
Except for changing to l, a transparent transfer paper for electrophotography was obtained in the same manner.

Example 5 A transparent transfer paper for electrophotography was obtained in the same manner as in Example 1, except that the pulp slurry temperature was changed to 42 ° C.

Example 6 A transparent transfer paper for electrophotography was obtained in the same manner as in Example 4, except that the temperature of the pulp slurry was changed to 42 ° C.

Example 7 A transparent transfer paper for electrophotography was obtained in the same manner as in Example 1, except that the temperature of the pulp slurry was changed to 30 ° C.

Example 8 A transparent transfer paper for electrophotography was obtained in the same manner as in Example 1 except that the temperature of the pulp slurry was changed to 35 ° C.

Example 9 A transparent transfer paper for electrophotography was obtained in the same manner as in Example 1, except that the temperature of the pulp slurry was changed to 40 ° C.

Comparative Example 1 After the bleached kraft pulp (NBKP) of our own softwood was bleached at a concentration of 3%, the Canadian freeness of the pulp was reduced to 40 ml using a double disc refiner and a deluxe finer (both manufactured by Aikawa Tekko). Beated until it was. Thereafter, an electrophotographic transparent transfer paper having a basis weight of 75 g / m ² was produced by a fourdrinier paper machine. In the size press, a styrene-acrylic copolymer (made by Harima Kasei, Harsize K
N500) was applied at 0.1 g / m ² and then the density was 1.
Machine calendering was performed so as to be 0 g / cm ³ .

Comparative Example 2 In Comparative Example 1, the pulp was modified to a Canadian freeness of 110.
Except for changing to ml, a transparent transfer paper for electrophotography was obtained in the same manner.

Comparative Example 3 In Comparative Example 1, the Canadian modified freeness of the pulp was 150.
Except for changing to ml, a transparent transfer paper for electrophotography was obtained in the same manner.

The transparent papers produced in Examples and Comparative Examples were evaluated by the following evaluation methods, and the results are shown in Table 1.

(Canadian modified freeness) The Canadian modified freeness of pulp was determined in accordance with JIS except that 0.5 g of pulp was dried and the sieve plate was made of 80-mesh bronze wire.
It is a value measured according to the Canadian standard form of P8121.

(Pulp Slurry Temperature) The pulp slurry temperature is a value measured using a red liquid bar thermometer (0 to 100 ° C.).

(Transparency) Transparency is measured according to JIS P8138.
This is a value obtained by subtracting the opacity measured in accordance with the method B from 100% from 100%.
% Or more is required.

(Tear strength) The tear strength is measured according to JIS.
This is a value measured according to P8116.

(Cracks) Cracks were generated in an electrophotographic copying machine (FX5
080, manufactured by Fuji Xerox Co., Ltd.) is a result of a visual evaluation of the state of cracks at both ends of the fold when the paper immediately after printing is folded in two. 4 was rated good, 3 was fairly bad, 2 was bad, and 1 was very bad. The current level is 3.

[0040]

[Table 1]

From the results of Examples 1 to 9 and Comparative Examples 1 to 5, it is clear that when the tear strength of the electrophotographic transparent transfer paper is 22 gf or more, cracking after heating printing is satisfactory. In addition, the Canadian modified freeness of pulp is 50-100.
It is clear that the transparency of the electrophotographic transparent transfer paper can be satisfied when the volume is ml. It is apparent that when the pulp slurry temperature before beating is 30 to 40 ° C., a transparent transfer paper for electrophotography having good cracking and transparency after heating and printing can be obtained.

[0042]

The transparent transfer paper for electrophotography of the present invention was prepared by raising the temperature of the pulp slurry before beating the pulp to 30 to 40 ° C. and beaten it to a Canadian modified freeness of 50 to 100 ml. It has high transparency and excellent tear strength, and has few cracks after heating and printing.

Claims (2)

[Claims] 1. Canadian modified freeness (pulp is dried to 0.
5 g was collected and the sieve plate was changed to a 80-mesh plain woven bronze wire, except that the pulp was beaten to 50 to 100 ml. Paper, the tear strength of the transparent transfer paper for electrophotography (JIS
P8116) is 22 gf or more. 2. A method for producing a transparent transfer paper for electrophotography, wherein the pulp slurry temperature is raised to 30 to 40 ° C. before beating the pulp.