JP2001281903A - Electrophotographic transfer paper and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monochromatic or full-color electrophotographic transfer paper having little curling after printing in a copying machine or printer and having good traveling property and workability by using a fast large width paper making machine. SOLUTION: The electrophotographic transfer paper and its manufacture method have the following features. When the fiber orientation index and the fiber orientation angle of the top and back faces of the paper are continuously measured for the full width on a paper making machine by using an on-line surface fiber orientation meter, both of the standard deviations (EσF) and (EσW) of the fiber orientation index of the top face and of the back face, respectively, are <= 0.02, and both of the standard deviations (AσF) and (AσW) of the fiber orientation angle of the top face and back face are <=10 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to electrophotographic printing paper manufactured by a general paper machine. More specifically, the present invention relates to a transfer paper which has a small curl after printing, good running properties, and excellent workability in a copying machine and a printer which are thermally fixed.

[0002]

2. Description of the Related Art The fiber orientation of paper is an important characteristic related to dimensional stability-related quality, and it is necessary to maintain the fiber orientation at an appropriate value by controlling papermaking conditions. Until now, there have been several methods for controlling the dimensional stability of paper by optimizing the fiber orientation characteristics.For example, as a method of suppressing the heat curl at the time of fixing the transfer paper for electrophotography, the front and back fiber orientation indexes are used. A method for defining the difference (Japanese Patent Laid-Open No. 6-138688),
One that defines the fiber orientation angle of all layers (Japanese Unexamined Patent Application Publication No.
No. 60) and a method of adjusting the difference in fiber orientation angle between front and back (Japanese Patent Application Laid-Open No. 6-257859). All of these methods are particularly suitable for paper manufactured by a high-speed wide-width paper machine which has been rapidly spreading in recent years. In the case of (1), there is a disadvantage that curling cannot be sufficiently prevented. In any of these methods, it takes time and effort to cut the winding once wound on a reel, sample it to an appropriate size, and then measure it. This is because the fiber orientation characteristics of the paper positioned at the position (1) have to be expected, and it is difficult to sufficiently grasp the variation in the width direction and the variation with time. In the case of mass production with a high-speed wide-width paper machine, it is difficult to stabilize the quality level at a high level by these methods because the fluctuation in the width direction and the flow direction of the paper machine is large.

As a method for improving the dimensional stability of PPC paper or the like, a method of defining the freeness of disintegration on the front and back of the paper or the difference between the front and back of the amount of fine fibers, that is, the difference in freeness of 30 m is used.
By controlling the difference in the amount of fine fibers to 3% or less (Japanese Patent Application No. 8-294003), a fixed amount of heat curl at the time of fixing in a copying machine or a printer is controlled. There are things to keep below. However,
These methods also require a long time for measurement and cannot measure many samples at a time. Therefore, it has been difficult to suppress curl in mass production in recent high-speed wide paper machines.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a high-speed wide-width paper machine which has a low curl after printing in a copying machine and a printer and has good running and workability. And transfer paper for full color electrophotography.

There have been many studies on fiber orientation characteristics and paper quality, and the present inventors have found that fiber orientation strength, fiber orientation angle and dimensional stability of paper are particularly closely related. Heading.

[0006] For paper that is printed by electrophotography on a single sheet, such as PPC paper or laser beam printer paper, heated curl after printing has the highest quality. In an electrophotographic copying machine or printer, the water inside the paper is rapidly heated and evaporated by heating with a fixing roll at about 180 ° C. in the fixing step. Although the paper curls due to the shrinkage caused by the dehumidification, the curl increases when the fiber orientation characteristics of the paper are not appropriate and the dimensional stability is poor. When the degree of curl becomes large, a traveling trouble in a copying machine or a printer is apt to occur, and the integration in a sorter or a tray is deteriorated, and at the same time, there is a problem in workability in a subsequent process. In particular, in recent years, the traveling path of paper has become complicated due to downsizing of a copying machine, front-loading paper feeding, or frequent use of double-sided copying, and the case where slight curl causes trouble in traveling has increased. In addition, a high-speed laser beam printer that performs a large amount of printing by an electrophotographic method is remarkably popular. Since the printing is performed continuously for 1000 sheets or more, a paper having a smaller curl is required.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, using an on-line fiber orientation meter, the fiber orientation index and fiber orientation angle of the front and back of the paper are determined on a paper machine. When continuously measured over the entire width, the standard deviation (Eσ _F ) of the fiber orientation index of the front surface and the standard deviation (Eσ _W ) of the fiber orientation index of the back surface are both 0.02 or less, and the fiber orientation angle of the front surface. The present invention has been attained by obtaining an electrophotographic transfer paper characterized in that the standard deviation (Aσ _F ) and the standard deviation (Aσ _W ) of the fiber orientation angle on the back surface are both 10 degrees or less.

In an electrophotographic copying machine or printer, moisture in the paper evaporates rapidly due to heating in the fixing process, and the paper shrinks. It is well known that the amount of deformation of the paper due to this dehumidification greatly affects the fiber orientation of the paper, and that there is a correlation between the two. That is, it is said that the amount of shrinkage of the pulp fiber constituting the paper by heating is about 20 to 50 times larger in the horizontal direction of the pulp fiber than in the vertical direction. Therefore, the strength and direction of the fiber orientation of the pulp fiber, that is, the fiber orientation index and the fiber orientation angle greatly affect the expansion and contraction behavior of the paper. It is well known that the fiber orientation of paper greatly varies depending on the position of the paper machine, and is particularly remarkable in recent wide paper machines. The fiber orientation characteristics also vary considerably due to changes in machine conditions, variations in the properties of the raw pulp, and the like. Therefore, when controlling the fiber orientation characteristics, the curl after printing cannot be controlled within a certain range by managing only a specific take-up position. In the present invention, over the entire width of the machine, using an online fiber orientation meter capable of measuring the fiber orientation characteristics continuously for a long time, the fiber orientation index of the front and back, and the fiber orientation angle are measured,
By controlling these standard deviations to 0.02 or less and 10 degrees or less, respectively, it is possible to reduce the fluctuation of the size of the curl after printing. Also, the curl after printing is greatly affected by the difference between the front and back of the fiber orientation index and the front and back of the fiber orientation angle. In the present invention, the effect is more remarkable by setting the front-back difference of the entire width average value of the fiber orientation index to -0.02 to 0.02 and the front-back difference of the full width average value of the fiber orientation angle to -10 to 10 degrees. Become.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The fiber orientation index and fiber orientation angle of front and back in the present invention can be determined by the following methods, that is, JP-A-7-229831, JP-A-7-311142 and JP-A-6-257092. JP, JP-A-10-46
According to any of the methods described in Japanese Patent No. 483, the measurement can be easily performed on a paper machine for a long time over the entire width.

First, light is irradiated perpendicularly to the paper surface of the running paper, and the parallel light centering on the intersection of the plane parallel to the paper surface on the non-polarized light incident side of the paper surface and the incident light axis. At eight or more locations on the circumference of a flat surface, or at four locations on a semicircle, the light reflected by the paper surface is captured almost simultaneously, and the irradiation position of the non-polarized light is scanned in the cross machine direction of the paper machine. Then, the intensity of the reflected light is measured.

The measured values thus obtained are calculated using the following equations to calculate the fiber orientation index and fiber orientation angle.

F (θ) = C (1 + ηCOS2 (θ−α)) where F is the light intensity, θ is the arrangement angle of the light receiving means, C is the average value of the reflected light intensity, and α is the fiber orientation angle. (Representing the orientation direction), and η is the fiber orientation index (representing the strength of orientation).

The average value of the fiber orientation index and the entire width of the fiber orientation angle was an average value of at least 30 points. The standard deviation was calculated from all the data by continuously measuring at least 30 points in the full width for at least one hour.

Formulas for calculating the average fiber width index (E), the standard deviation (Eσ), and the average fiber orientation angle (A) and the standard deviation (Aσ) are as follows. Here, M is the number of measurements in the width direction, and N is the total number of samples.

[0015]

(Equation 1)

As a method for producing the transfer paper for electrophotography of the present invention, various types of paper machines such as a fourdrinier paper machine, a hybrid former, and a gap former can be used. As the raw material pulp, all materials generally used as raw material pulp for papermaking, such as bleached kraft pulp of hardwood and softwood, thermomechanical pulp and waste paper deinked pulp, can be used.

As a method for controlling the fiber orientation index, J
/ W ratio (ratio of jet flow speed to wire running speed), slice opening, slice lip position adjustment, etc. For controlling fiber orientation angle, slice resolution, recirculation valve opening, bleeder, edge Adjustment of flow and the like can be used. In the present invention, a good transfer paper for electrophotography can be obtained particularly in a combination of adjustment of the J / W ratio and the edge flow, or adjustment of the slice lip position and the recirculation valve opening.

The on-line surface fiber orientation meter is installed in the middle of or after the dryer part of the paper machine. It can be installed before and after size press or before winding.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments showing the present invention will be described below in detail. The present invention is not limited to the following examples. <Measurement of Fiber Orientation Index and Fiber Orientation Angle> The fiber orientation index and fiber orientation angle are described in the paper pulp and paper technology association, March 1999, p.
It measured using the online surface fiber orientation meter described in 55-60. That is, in this method, light (randomly polarized light) having no change characteristic was incident on the paper surface during traveling, and the light intensity distribution reflected on the paper surface was measured simultaneously by eight light receiving units. The on-line surface orientation meter was installed on the BM counting section and the lower head immediately before the reel end, for the F plane and for the W plane. The fiber orientation index and the fiber orientation angle were calculated by the following equations.

F (θ) = C (1 + ηCOS2 (θ−α)) where F is the light intensity, θ is the arrangement angle of the light receiving means, C is the average value of the reflected light intensity, and α is the fiber orientation. The angle (representing the orientation direction) and η are the fiber orientation index (representing the strength of orientation).

The average value of the fiber orientation index and the total width of the fiber orientation angle was 30 points. The standard deviation was obtained by measuring 30 points of the full width continuously for one hour and calculating from all the data.

The formulas for calculating the average fiber width index (E), the standard deviation (Eσ) and the average fiber orientation angle (A) and the standard deviation (Aσ) are as follows. Here, M is the number of measurements in the width direction, and N is the total number of samples.

[0023]

(Equation 2)

<Evaluation Test> The size of the curl after printing and the tray accommodating property were measured by using a high-speed laser printer FX-4660 (135 sheets / min) manufactured by Fuji Xerox.
Evaluation was performed by continuously printing 0 sheets. The size of the curl is
The average and maximum values of the plane curl height (H) were measured for the 1, 100, 250, 400, and 500th sheets (FIG. 1). For the size of the torsion curl, the torsion curl value (D) was measured (FIG. 2). The accommodating property was evaluated based on the number of trays accommodated (the maximum number of accommodated sheets: 500). <Examples 1 to 3 and Comparative Examples 1 to 3> Using hardwood bleached kraft pulp with a freeness of 450 ml, a rosin sizing agent, talc, and a sulfuric acid band were added as additive chemicals in terms of absolute dry weight percentage of pulp of 0.3, respectively. Weight%, 10.0 weight%, 2.
The slurry to which 0% by weight was added was common to Examples and Comparative Examples, and J / W was measured using a hybrid former paper machine.
While adjusting the fiber orientation index and the fiber orientation angle by changing the ratio and the edge flow, PPC at a paper making speed of 1000 m / min.
Paper was made. The grammage was 64 g / m ² .

[0025]

[Table 1]

<Examples 4 to 6, Comparative Examples 4 to 6> Freeness 4
00ml hardwood bleached kraft pulp and freeness 150
0.1% by weight, 5.0% by weight, and 0.5% by weight of alkenyl succinic anhydride, calcium carbonate, and cationized starch as additive chemicals on an absolute dry weight basis, respectively. The slurry to which weight% is added is common to the example and the comparative example, and the difference in the fiber orientation index between the front and back and the difference in the fiber orientation angle between the front and back are adjusted using the fourdrinier paper machine by the slice lip position and the recirculation valve opening. 7 while making
Laser beam printer paper was made at 00 m / min. The grammage was 64 g / m ² .

[0027]

[Table 2]

[Brief description of the drawings]

FIG. 1 shows a method of measuring a planar curl height after transfer and printing of A4 size electrophotographic transfer paper.
The curled transfer paper (1) is placed on the flat table (2) with the curl surface facing up, and the height (H1, H2, H3, H4) warped from the table surface is measured at four corners. .

FIG. 2 shows a method for measuring a twisting curl value after transfer and printing of A4 size electrophotographic paper. One side of the transfer paper (1) is sandwiched between the hanging fittings (2), and the vertical distance between the lower right corner (3) and the lower left corner (4) of the suspended transfer paper is defined as a screw recurl value (D).

Claims (3)

[Claims] 1. A standard deviation (Eσ _F) of the fiber orientation index of the surface when the fiber orientation index and the fiber orientation angle on the front and back of the paper are continuously measured over the entire width on a paper machine using an online surface fiber orientation meter. ) And the standard deviation (Eσ _W ) of the fiber orientation index of the back surface are both 0.02 or less, and the standard deviation (Aσ _F ) of the fiber orientation angle of the front surface and the standard deviation (Aσ _W ) of the fiber orientation angle of the back surface. Are both less than 10 degrees. 2. Using the online surface fiber orientation meter, the fiber orientation index of the paper front and back, and when the fiber orientation was continuously measured on the paper machine, full width average of fiber orientation index of the surface (E _F) The difference (E _W -E _F ) between the average width (E _W ) of the fiber orientation indices of the fiber and the back surface is −0.02 to 0.02, and the average width (A _F ) of the fiber orientation angle on the front surface is (A _F −A _W ) between the average width (A _W ) of the fiber orientation angles of the fiber and the back side is −10 degrees or more.
The transfer paper for electrophotography according to claim 1, wherein the angle is 10 degrees. 3. An on-line surface fiber orientation meter is installed in the middle of or after the dryer part of the paper machine, and the standard deviation (Eσ _F ) of the fiber orientation index on the front surface and the standard deviation (Eσ _W ) of the fiber orientation index on the back surface are set. ) Are both 0.02 or less,
A method for producing an electrophotographic transfer paper in which both the standard deviation (Aσ _F ) of the fiber orientation angle on the front surface and the standard deviation (Aσ _W ) of the fiber orientation angle on the rear surface are 10 degrees or less.