JPH08202068A - Transparent transfer paper for electrophotography - Google Patents

Abstract

PURPOSE: To improve transparency and to decrease undulations after thermal printing by composing the above paper of wood pulp having the filtration coefft. measured by a filtration resistance measuring tester in specific range. CONSTITUTION: The wood pulp of which the filtration resistance coefft. Kr measure by the filtration resistance measuring tester and expressed by Kr=-t/[1n 1-(q/Q)}+(q/Q)] is in the range of 330 of 2200 seconds is used. In the equation, (t) denotes filtration time (sec), Q denotes the volume (ml) of the water of a sample, (q) denotes a filtrate amt. (ml). The measurement is executed by first controlling the temp. of heavily beaten pulp to 40 deg.C prior to the measurement. Next, the pulp slurry subjected to the temp. control is put into a cylindrical vessel 3 with a baffle installed in a heat insulating layer 2. While the filter liquid is kept stirred slowly by a stirrer 1 having four sheets of stirring vanes of square waves installed apart a gap from a bronze wire, a filter liquid outflow port 6 is opened and the filter liquid transmitted through the wire 5 is collected in the liquid receiving container 7. The weight is continuously measured at 1-second intervals by an electronic balance 8. The filtration resistance coefft. Kr is calculated from the recorded data of the filtrate amt.

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 use in electrophotographic copying machines and printers, and more particularly to a transparent transfer paper for electrophotography which is excellent in transparency and has less flicker after heating and printing. is there.

[0002]

2. Description of the Related Art For the purpose of obtaining a transparent transfer paper for electrophotography having a natural surface property, a paper is manufactured by using wood pulp having a low free drainage beaten in multiple stages. Also,
In recent years, with the increase in speed of electrophotographic copying machines, quality requirements for transparent transfer paper have become stricter, such as improvement in fluttering after heating printing.

In order to improve the dimensional stability of a paper made from a raw material having a low freeness, it is necessary to make beating as light as possible to improve the dehydration property in a press and to control the shrinkage during drying. Become. On the other hand, in order to obtain sufficient transparency, it is necessary to advance beating. In order to satisfy the two contradictory conditions, attempts have been made to select pulp, improve drainage property by adding a drainage improver, and optimize press and drying conditions.

[0004]

[Problems to be Solved by the Invention] While maintaining transparency,
In order to reduce the blistering after heating and printing, we examined the type of pulp used, the improvement of dewatering property by adding a drainage improver, and the press and drying conditions. However, no satisfactory result was obtained by either method.

The present invention relates to a transparent transfer paper for electrophotography containing a raw material which has been advanced in beating, and to improving the transparency and the flicker after printing by an electrophotographic copying machine or printer. That is, an object of the present invention is to provide a transparent transfer paper for electrophotography, which has less flutter after heating and printing.

[0006]

In order to solve the above-mentioned problems, the present inventors have made various studies on the drainage of the stock. As a result, the filtration resistance coefficient Kr measured by a filtration resistance measurement tester and represented by the following equation 2 (Equation 1) is 330 to
It was found that by using wood pulp in the range of 2200 seconds, it is possible to obtain a transparent transfer paper for electrophotography, which has less flicker after heating and printing.

[0007]

## EQU00002 ## Kr = -t / [ln {1- (q / Q)} + (q / Q)] Kr: Filtration resistance coefficient (sec) t: Filtration time (sec) Q: Volume of sample water ( ml) q: Drainage amount (ml)

The electrophotographic transparent transfer paper of the present invention will be described in detail below. Conventionally, Canadian Standard Freeness Tester and Shopper Wrigler Tester have been used to evaluate drainage of beaten pulp. However, in these methods, a pulp with low drainage (hereinafter referred to as a heavy beating pulp), for example,
Sufficient evaluation could not be performed for pulps with a volume of 100 ml or less as measured by the Canadian Standard Freeness Tester.

Therefore, the present inventors have examined a drainage evaluation method which is an alternative to these methods. as a result,
By using the filtration resistance measurement tester shown in FIG. 1 and introducing the concept of the required filtration resistance coefficient Kr, it was found that the drainage evaluation of pulp can be performed.

The filtration resistance coefficient Kr in the present invention is a coefficient represented by the following mathematical expression 3 (Formula 1), and is described, for example, by Tsuchita et al., Journal of Paper and Pulp Technology, Vol. 26, No. 7, 1.
1-18 (1972).

[0011]

## EQU00003 ## Kr = -t / [ln {1- (q / Q)} + (q / Q)] Kr: Filtration resistance coefficient (sec) t: Filtration time (sec) Q: Volume of sample water ( ml) q: Drainage amount (ml)

When a transparent transfer paper for electrophotography according to the present invention is manufactured by a paper machine using heavy beating pulp, at least the slurry at the time of papermaking is taken into consideration in consideration of the dehydration property on the wire and the water squeezing property at the press part. It is necessary to raise the temperature to 40 ° C. or higher for papermaking. The present inventors consider such actual papermaking conditions and the measurement principle of the filtration resistance tester of the present invention,
The temperature and stirring conditions of the pulp slurry at the time of measurement were earnestly studied.

As a result, when the filtration resistance coefficient Kr of the heavy beating pulp is determined using the filtration resistance tester of the present invention,
(1) The temperature of the pulp slurry is raised to 40 ° C. or higher for measurement, and (2) the pulp slurry is continuously agitated by a stirrer during the measurement so that the slurry has a large concentration in the cylinder of the measuring machine. So that there is no gradient,
Moreover, they have found that it is necessary not to destroy the pulp mat layer formed during dewatering.

The filtration resistance measuring test method will be described in detail below with reference to the attached FIG. FIG. 1 is a schematic diagram of a filtration resistance measurement tester used in the measurement of the filtration resistance coefficient Kr in the present invention. Before measurement, use 500 ml of 0.4% by weight heavy pulp, which is the measurement stock, before measurement.
Adjust temperature to 0 ° C. Next, the temperature-controlled pulp slurry is put into a baffled cylindrical container 3 having a diameter of 10 cm provided with a heat retaining layer 2. The filtrate outlet 6 was opened while slowly stirring at 310 rpm with a stirrer 1 having four 2 cm × 1.5 cm square blade stirring blades installed with a 7 mm gap between the wire and a 70 mesh bronze wire 5 The filtrate that has passed through is collected in the receiving container 7, and its weight is continuously measured by the electronic balance 8 at 1 second intervals. Electronic balance 8
The measurement result of is recorded by the personal computer 10. The drainage time is 0 from the recorded drainage volume data.
The filtration resistance coefficient Kr was calculated by the method of least squares according to Formula 1 based on the amount of drainage during -40 seconds.

Next, the present inventors have tried various studies on the correlation between the beating condition of pulp and the physical properties of the transparent transfer paper for electrophotography, using the method described above. As a result, by using a wood pulp having a filtration resistance coefficient Kr of 300 to 2200 seconds measured under the conditions of a slurry temperature of 40 ° C. and a slurry concentration of 0.40% by weight with a filtration resistance measurement tester, fluttering after heating printing is achieved. It is possible to obtain a transparent transfer paper for electrophotography, which has a small amount.

If the filtration resistance coefficient Kr is less than 300 seconds, sufficient transparency cannot be obtained. Further, if the filtration resistance coefficient Kr exceeds 2200 seconds, the dehydration property and the water squeezing property are deteriorated, and accordingly, the blistering after heating and printing is deteriorated, which is not preferable.

The wood pulp used in the electrophotographic transparent transfer paper of the present invention includes NBKP, LBKP and NBS.
P, LBSP and the like. In use, several kinds of them are mixed and used at a ratio according to the purpose.

The wood pulp used in the present invention has a filtration resistance coefficient Kr of 330 to 22 by using a beating machine such as a double disc refiner, a deluxe finer or Jordan.
The paper is made after beating for 00 seconds.

The electrophotographic transparent transfer paper of the present invention contains, if necessary, dyes, fillers, sizing agents, fixing agents, dry paper strength enhancers and the like which are usually used in papermaking. It is also possible to apply a binder such as starch or polyvinyl alcohol or a conductive agent such as sodium chloride to the surface of the raw paper by a size press or the like.

The electrophotographic transparent transfer paper in the present invention is used as a recording material for electrophotographic copying machines, page printers, continuous printers applying this method, facsimiles, full color copying machines and the like. is there.

[0021]

The transparent transfer paper for electrophotography of the present invention has a filtration resistance coefficient Kr of 330 to 220 measured by a filtration resistance measurement tester.
A transparent transfer paper for electrophotography composed of wood pulp of 0 second has excellent transparency and little flicker after heating and printing.

[0022]

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

Example 1 NBKP having a weight average fiber length of 2.29 mm and a concentration of 3.0%
Was pretreated twice with a disc refiner equipped with a blade having a groove width of 6 mm and a groove depth of 5.5 mm, and then a groove width of 3 mm,
It was post-treated 8 times with a disc refiner equipped with a blade having a groove depth of 4.5 mm to produce beaten pulp having a filtration resistance coefficient Kr of 330.9 seconds. Using this pulp, a Fourdrinier paper machine was used to produce a transparent transfer paper for electrophotography having a pulp slurry temperature of 65 ° C. and a basis weight of 75 g / m ² . In the size press, oxidized starch was 1.5 g / m ² and sodium chloride was 0.1 g / m ^2.
m ^{2 was} coated, and then machine calendering was performed so that the density became 0.90 g / m ² , to obtain the electrophotographic transparent transfer paper of Example 1.

Example 2 Example 2 was repeated except that the number of post-treatments of the disc refiner was 13 and pulp having a filtration resistance coefficient Kr of 654.4 seconds was produced.
To obtain a transparent transfer paper for electrophotography.

Example 3 The same procedure as in Example 1 was repeated except that the number of post-treatments of the disc refiner was 20 and pulp having a filtration resistance coefficient Kr of 1915.2 seconds was produced. A transparent transfer paper for photographs was obtained.

Comparative Example 1 The same procedure as in Example 1 was repeated except that the number of post-treatments of the disc refiner was set to 7 and pulp having a filtration resistance coefficient Kr of 315.1 seconds was produced. A transparent transfer paper for photographs was obtained.

Comparative Example 2 The same method as in Example 1 was used except that the disc refiner was pretreated 4 times and posttreated 30 times to produce pulp having a filtration resistance coefficient Kr of 2511.1 seconds. Thus, a transparent transfer paper for electrophotography of Comparative Example 2 was obtained.

The electrophotographic transparent transfer papers of Examples 1 to 3 and Comparative Examples 1 and 2 produced as described above were evaluated by the following evaluation methods, and the results are shown in Table 1. [Transparency] Transparency is based on TAPPI standard method T-442su.
It is the value measured according to 72, and the higher the value, the higher the transparency. The transparency for electrophotography is required to have a transparency of 70% or more, preferably 72% or more.

[Bobbling] Bottling is the result of visual evaluation of blistering on the paper surface immediately after printing with an electrophotographic copying machine (FX5080, manufactured by Fuji Xerox Co., Ltd.). Δ: Many were marked as × The lower limit of quality is fluttering Δ, but it is desirable that it is ○.

[0030]

[Table 1]

Evaluation: By comparing the electrophotographic transparent transfer papers of Examples 1 to 3 with the electrophotographic transparent transfer papers of Comparative Examples 1 and 2, the transparency was confirmed when the filtration resistance coefficient Kr was less than 330 seconds. It can be seen that On the other hand, it can be seen that when the filtration resistance coefficient Kr exceeds 2200 seconds, the transparency is lowered and the flicker after heating and printing is deteriorated.

[0032]

As described above, the transparent transfer paper for electrophotography of the present invention, that is, the transparent transfer for electrophotography composed of wood pulp having a filtration resistance coefficient Kr of 330 to 2200 seconds measured by a filtration resistance measurement tester. It was revealed that the paper was excellent in transparency and had less flicker after heating and printing.

[Brief description of drawings]

FIG. 1 is a schematic view of a filtration resistance measurement tester used for measuring the filtration resistance coefficient Kr of the present invention.

[Explanation of symbols]

 1 Stirrer 2 Heat insulation layer 3 Cylindrical container 4 Beating pulp slurry 5 Wire 6 Filtrate outlet 7 Liquid receiving container 8 Electronic balance 9 RS232C cable 10 Personal computer

Claims (1)

[Claims] 1. A filtration resistance coefficient Kr measured by a filtration resistance measurement tester and represented by the following equation 1 (Formula 1) is 330 to
Transparent transfer paper for electrophotography made of wood pulp in the range of 2200 seconds. ## EQU1 ## Kr = -t / [ln {1- (q / Q)} + (q / Q)] Kr: Filtration resistance coefficient (sec) t: Filtration time (sec) Q: Volume of sample water ( ml) q: Drainage amount (ml)