JPH0248892B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing high-quality or medium-quality plain paper for use in a two-component toner heat-fixing type copying machine that prevents double feeding, and particularly to a method for feeding accumulated paper in a copying machine. This function prevents the problem of so-called "double feeding," in which two or more sheets of paper are fed at once when feeding stacked sheets of paper from the top to the copying unit of a single-sheet copying machine. The invention relates to a method of manufacturing copy paper that enables the paper to be sent. More specifically, the purpose is to produce paper inexpensively and effectively, and at the same time to provide the best functionality for the purpose of copying paper. Note that lower-grade paper is rarely used as copying paper due to its high-speed running properties and image reproducibility. Generally, when copying, A column 3 size, A column 4 size
A pile of paper cut into small sizes, such as 4 size in row B, 5 size in row B, etc., is placed in the paper feed section of the copying machine, and one sheet from the top of the stack is fed into the copying section one by one. In some cases, double feeding may occur. Double feeding troubles not only make copying operations inefficient and uneconomical, but also burden those engaged in copying with unnecessary labor. In order to prevent the occurrence of double feeding, various types of double feeding prevention devices have been devised by copying machine manufacturers and are actually installed in copying machines. As a result, although it was possible to prevent double feeding to a considerable extent, it is still far from perfect.
The reason for this is that the physical properties of the paper used for copying have a large effect on double feeding. The actual basis weight of paper,
Physical properties such as thickness, density, stiffness, smoothness, static friction coefficient, and surface electrical resistance are considered to be important factors in the occurrence of double feeding. From this viewpoint, the present inventors also investigated the relationship between the physical properties of paper and double feeding, and made efforts to find out the factors that affect double feeding, but were unable to reach a firm conclusion. At this point, we recognized the need to further consider the following two matters. The first is the fact that the static friction force of copy paper is not constant. In this case, constant is
Indicates that the measured value is within a certain distribution including variation. That is, when the static friction force is sequentially measured for the first and second sheets of stacked paper, and the second and third sheets, areas where the static friction force is low appear every few sheets. This fact is because when cutting paper into small pieces in the finishing process, the paper is not cut one by one, but the paper unrolled from several rolls is stacked and cut, so every few sheets become one block. It is. The static friction force of the paper within these several blocks is called the intralayer static friction force, and the static friction coefficient is called the intralayer static friction coefficient; the static friction force between the blocks is called the interlayer static friction force, and the static friction coefficient is called the interlayer static friction coefficient. The difference or the difference between both static friction coefficients is the cause of double feeding. A second additional consideration is the paper feeding mechanism. In roller feeding methods, a rubber roller is typically placed over the stack of paper when feeding paper in a copier. This rubber roller functions to feed the paper into the copying section of the copying machine by rotation, but in the case of a rubber roller that uses a reverse buckle system and is equipped with a separation claw (snubber) at the tip of the paper feed section, the rubber roller feeds the paper into the copying section of the copying machine. Before it rotates, it rotates in the opposite direction once to separate the paper from the separating claw, bends the edge of the paper, separates it from the second sheet, and then rotates in the forward direction to feed the paper. There is. The flexibility of the paper at this time has a close relationship with the occurrence of double feeding. The present inventors conducted various studies on the relationship between the above two factors and double feeding, and obtained the results shown in the figure. The figure is an explanatory illustration of the basic principle of the present invention for A-column 4-size copy paper, where the vertical axis represents the double feed ratio P, and the horizontal axis represents the difference Δf (gf ), or the difference Δμ between the intralayer static friction coefficient and the interlayer static friction coefficient. In addition, in the figure,
Dotted lines indicate limit values. The double feed ratio is a value that indicates the number of times double feed occurs between blocks when five sets of paper blocks (four sheets in this experiment) are subjected to a copying machine test.For example, in the case of 5/5, the total This means that a double feed occurred between all blocks. As is clear from the drawing, double feeding occurs quite frequently in the range of Δf≧15 or Δμ≧0.03, but in the range of Δf<15 or Δμ
If the value is <0.03, double feeding will not occur at all. As described above, in order to prevent the occurrence of double feeding of copy paper, the difference Δf between the intralayer static friction force and the interlayer static friction force under a load roughly equivalent to the load of the paper feed roller of a copying machine,
Or the difference Δμ between the intralayer static friction coefficient and the interlayer static friction coefficient
If Δf or Δμ is equal to a certain limit value or Δf or Δμ is larger than the limit value, there is a high risk of double feeding when feeding this paper, and conversely Δf Alternatively, if Δμ is smaller than the limit value, there is no danger of double feeding and the paper can be used as copying paper with peace of mind. A certain limit value can be set for Δf or Δμ because
This is due to the flexibility of the paper edge caused by the paper feeding mechanism, and is also applicable when the reverse buckle method is used and there is no separation claw, and when the reverse buckle method is not adopted but a separation claw is provided. I can do it. If there is no separating claw and the reverse buckling method is not adopted, the deflection is irrelevant and there is no limit value, and the double feeding ratio is directly determined by the magnitude of Δf or Δμ. That is, the larger Δf or Δμ is, the larger the double feeding ratio becomes. Based on the above experimental facts, the inventors set Δf to 15 gf.
As a result of intensive research aimed at reducing Δμ to 0.03 or less, we have found that adding a certain type of silica pigment internally or coating it on the surface during the entire manufacturing process of copying paper has a remarkable effect on reducing Δf or Δμ. I came to discover something. The silica pigment of the present invention is mainly obtained by decomposing an aqueous sodium silicate solution with an acid or salt, and has a specific surface area of 50 to 400 m ² /g, and is a white fine powder of hydrated silicic acid or silicate, which is generally referred to as white carbon. It refers to ultrafine particles of silicic anhydride, generally called colloidal silica, with a particle size of 10 mμ to 1 μm, obtained from an aqueous sodium acid solution by operations such as cation exchange, heat aging, and heel growth. If the particle size of the silica pigment used in the method of the present invention exceeds 1 μm, it is undesirable because it causes problems such as decreased performance due to falling off during the cutting process, powder falling off when running in a copying machine, and abrasion of the photosensitive drum. Examples of uses of silica pigments in paper manufacturing and processing include: In the production of newsprint, white carbon is added to the paper stock at a ratio of several percent or less to help improve opacity after printing. This utilizes the oil-absorbing ability of white carbon, and is intended to prevent printing ink from penetrating the back side and preventing print-through, making it an interesting application for reducing the weight of newsprint. The second is an example in which fine silica pigments are applied to the image surface of photographic paper, diazo-sensitive paper, and high-grade printing paper.Similar to newsprint, the absorbency and surface area expansion properties of silica pigments are used to develop the The purpose is to prevent liquid and printing ink from penetrating into the paper layer and improve the density and freshness of images. The third application is to apply silica pigment to the surface of corrugated board liners or cardboard boxes after carton manufacturing, kraft paper for heavy packaging, or kraft paper bags after bag manufacturing to prevent slip troubles in paper carton and paper bag filling lines. This helps prevent cargo from collapsing during transportation.
This takes advantage of the non-slip properties of silica pigments. As can be seen from the above examples, silica pigments are sometimes used in paper manufacturing or paper processing, but this is due to the difference Δf between the intralayer static friction force and the interlayer static friction force of copy paper, or the difference Δf between the intralayer static friction coefficient and the interlayer static friction coefficient. This is completely unrelated to the purpose of the present invention, which is concerned with the difference Δμ from the static friction coefficient. To apply the silica pigment for the purpose of the present invention, an aqueous dispersion of white carbon is used, or if it is a powder, it is dispersed in water, and colloidal silica is diluted with its residual water and used in any concentration. . As a method of applying silica pigment to paper, known methods such as internal addition to the paper stock, spraying on the paper surface, and coating can be used, but from the viewpoint of workability, economy, and effectiveness, internal addition or size Application by press is particularly suitable. Good results can also be obtained when used in combination with other pigments, fillers, or paper chemicals such as starch and PVA. Although the mechanism by which the silica pigment contributes to the reduction of Δf or Δμ of copy paper according to the present invention is not clear, the silica pigment with a large specific surface area changes the properties of the paper surface through its active group, and This is presumed to be because even if the paper is overlapped and cut, there is no significant difference in the static friction force or static friction coefficient on the paper surface. Examples will be described below. The measurement of static friction force and the double feeding test in the examples were carried out as follows. A set of 4 test papers cut into 4 sizes in A row was passed through a test calendar (made of steel, roll surface length 250 mm, roll diameter 80 mm) without pressure, so that only the weight of the roll was applied to the paper. . Several sets of these blocks were made and left in a piled state for 24 hours. A pile of paper is placed on a wooden stand, and a weight of 500 gf with rubber attached to the bottom is placed on top of the pile. is pulled horizontally, and the force is measured using a Tensilon UT model (manufactured by Toyo Baldwin). As a result, the static friction force and the dynamic friction force between the first sheet of paper and the second sheet of paper were measured simultaneously, and the value of the static friction force was taken as the friction force. In addition, the static friction coefficient was obtained by dividing the frictional force by the weight of the weight (500gf), and the weight of the paper was ignored. Hereinafter, similar experiments were repeated to measure the static friction force and static friction coefficient within and between the layers, and the average differences were defined as Δf and Δμ. On the other hand, another calendered pile was prepared, and a double feeding test was conducted on five sets of blocks using a two-component toner heat-fixing copying machine (Fuji Xerox 4000). Since double feeding occurs between layers, the results are expressed in terms of the number of times it occurs. Double feeding is generally tested on at least several hundred sheets of paper, but when using this test method, it is possible to completely understand the tendency of double feeding with a small number of test papers. Example 1 From paper stock of LBKP (350 ml of CSF) 100% (hereinafter, all percentages indicate weight %), size 0.5% (based on pulp), and ban sulfate ±0.5% (as Al ₂ O ₃ , based on pulp) Paper with a basis weight of 64 g/m ² was made, and a surface sizing liquid with an oxidized starch concentration of 3% was applied using a size press. The filler is white carbon (manufactured by Mizusawa Chemical Co., Ltd., trade name Mizukasil P-527, average particle size 20 mμ)
was added so that the ash content in the paper was 6.5%. For comparison, ordinary talc and kaolin were added at an ash content of 6.0% and 8.0%, respectively. The static friction force and static friction coefficient of these papers were measured, and the effectiveness was further determined by a double feeding test. The results are shown in Table 1. Other physical property values of the paper are also listed in Table 1 for reference.

【table】

[Table] As is clear from Table 1, by internally adding silica pigment to the paper stock, there is no occurrence of double feeding. On the other hand, when approximately the same amount of talc or kaolin is added, double feeding occurs in 2 out of 5 blocks. In these examples, the conditions of Δf<15 and Δμ<0.03 match well with the results of the actual double feeding test. Example 2 Using the same paper stock as in Example 1, the internally added filler was kept constant at 10% (ash content in the paper), and the filler blending ratio was white carbon/talc of 100/0 and 50/0.
It was changed to 50, 30/70, 20/80, 10/90, and 0/100. Here, the white carbon used is trade name Pita Seal #1500 (manufactured by Taki Chemical Co., Ltd., average particle size 20 m).
μ) was used. All surface sizing was done at an oxidized starch concentration of 5%. The results are shown in Table 2.

【table】

[Table] From the results in Table 2, it is recognized that when the filler addition rate is 10% (as ash content in paper), white carbon can be replaced with inexpensive talc to avoid double feeding. However, the substitution rate is limited to 80 parts by weight, and if the substitution rate exceeds that, there is a risk of double feeding problems. As in Example 1, Δf<15,
The condition of Δμ<0.03 has an extremely good correlation with the occurrence of double feeding. It was confirmed that the paper to which white carbon was added internally had no problems with copying operations other than feeding, and the image quality was good. Example 3 Using the same stock as in Example 1, 6.5% talc
(as ash in the paper) was added internally to make paper. Next, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name Snowtex C, average particle size 20 mμ) was added to the surface sizing solution containing 5% oxidized starch in an amount of 0.5, 1,
It was added at varying concentrations of 3% (solid content). The results in this case are shown in Table 3 in comparison with the case without the addition of colloidal silica.

【table】

[Table] As is clear from Table 3, when the surface sizing liquid contains only starch, double feeding occurs in 2 out of 5 blocks, but when colloidal silica is added, double feeding does not occur even at a concentration of 0.5%. do not have.
Furthermore, the conditions of Δf<15 and Δμ<0.03 are also clearly established. On the other hand, image tests for copying machines have also shown that the addition of colloidal silica to the surface sizing liquid actually helps improve image quality.

[Brief explanation of the drawing]

The figures are explanatory illustrations of the basic principle of the invention. Vertical axis: double feed ratio P, horizontal axis: difference Δf (gf) between the static friction force within the layer and the static friction force between the layers, or the difference Δμ between the static friction coefficient within the layer and the static friction coefficient between the layers, dotted line: limit value.

Claims (1)

[Scope of Claims] 1. In the manufacturing process of high-quality or medium-quality copying paper, 2 to 10% by weight of silica pigment with a particle size of 1 μm or less is added to the paper by internal addition to the paper stock,
A method for manufacturing copying paper for a two-component toner heat fixing type copying machine, which comprises stacking several sheets of paper and cutting them. 2. In the manufacturing process of high-quality or medium-quality copying paper, 0.5 to 3% by weight of silica pigment with a particle size of 1 μ or less is applied to the paper surface by applying it to the paper,
A method for manufacturing copying paper for a two-component toner heat fixing type copying machine, which comprises stacking several sheets of paper and cutting them.