JPH0241746B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for processing copy paper, and more specifically, the present invention relates to a method for processing copy paper, and more particularly, to a problem caused by so-called "double feeding," in which multiple sheets are fed at once in a stacked state when feeding accumulated paper in a copy machine. The present invention relates to a finishing method for obtaining copy paper that can be fed smoothly without causing any damage.
That is, the aim is to manufacture paper inexpensively and efficiently and to provide the best functionality for the purpose of copying paper. Generally, when copying, A column 3 size, A column 4 size
A pile of sheets 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 of the copying machine. This is the normal state. However, in some cases, the topmost sheet of paper may be fed along with a second sheet of paper, or in severe cases, even the sheets below it may be fed into the copying section at the same time. be. In the present invention, this is referred to as "multiple feeding." Double feeding troubles not only make copying operations inefficient and uneconomical, but also burden those involved in copying with unnecessary labor. In order to prevent the occurrence of double feeding, copying machine manufacturers have devised and researched various double speed prevention devices and are actually installing them in copying machines. As a result, the effect of preventing double feeding has been achieved to a considerable extent, but at present it has not yet reached the level of being sufficient. In fact, various physical properties of paper, such as basis weight, thickness, density, stiffness, smoothness, coefficient of friction, and surface electrical resistance, are considered to be important factors in the occurrence of double feeding. The present inventors also investigated the relationship between the physical properties of paper and double feeding from this perspective, and
Efforts were made to investigate the factors affecting double transportation, but no firm conclusion could be reached. In addition, we recognized the need to further consider the following two matters. That is, the first is the fact that the frictional force of the copy paper is not constant. The meaning of "constant" means that it is within a certain distribution including variations in the specified value. i.e. 1 of the paper pile
When the frictional force is measured sequentially, such as from the second sheet to the second sheet, or from the second sheet to the third sheet, areas with low frictional force appear every few sheets. This is because when cutting paper into small pieces in the finishing process, the paper is not cut one sheet at a time, but the paper fed out from several rolls is stacked and cut, so every few sheets are cut into one block. It is. If the frictional force of the paper within these several blocks is called the intralaminar frictional force, the friction coefficient is called the intralaminar frictional coefficient, the frictional force between blocks is called the interlaminar frictional force, and the frictional coefficient is called the interlaminar friction coefficient. Difference in frictional force (△f),
Alternatively, it was found that the difference (△μ) between the two friction coefficients was the cause of double feeding. The second reason is that the paper feeding mechanism is a major factor. When feeding paper in a copier, a rubber roller is usually placed on top of the stack of paper in roller feeding systems. This rubber roller functions to feed the paper into the copying section by rotating, but if the roller uses a reverse buckle system and is equipped with a separation claw (snubber) at the tip of the paper feed section, it will rotate in the direction in which the paper travels. The mechanism is such that the paper is rotated in the opposite direction once before, separating the paper from the separating claw, bending the edge of the paper, separating it from the second sheet, and then rotating in the forward direction to feed the paper. 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 FIG. 1. FIG. 1 is an explanatory diagram 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 intralayer frictional force and the interlayer frictional force. It shows the difference Δf (gf) or the difference Δμ between the intralayer friction coefficient and the interlayer friction coefficient. Double feeding ratio is a value that indicates the number of times double feeding occurs between blocks when 5 sets of paper blocks (4 sheets in this experiment) are subjected to a copying machine test, and if it is 5/5, all blocks are This means that a double feed occurred between the two. As is clear from Figure 1, △f≧15 or △μ
In the range of ≧0.03, double feeding occurs quite frequently, but △f
<15 or Δμ<0.03, double feeding will not occur at all. As mentioned above, in order to prevent the occurrence of double feeding of copy paper, the difference △f between the intralayer frictional force and the interlayer frictional force under a load roughly equivalent to the load of the copying machine's paper feed roller, or the difference △f between the intralayer friction coefficient and the interlayer friction coefficient. It is sufficient to monitor the difference △μ in the friction coefficient, and if △f or △μ is equal to a certain limit value, or if △f or △μ is larger than the limit value, the double feed for feeding this paper is There are many dangers; conversely, if Δf or Δμ is smaller than the limit value, there is no danger of double feeding and it can be used as copying paper with peace of mind. The fact that a certain limit value can be set for △f or △μ should be attributed to the flexibility of the paper edge caused by the paper feeding mechanism, and when the reverse buckle method does not have a separation claw, and the reverse buckle method is adopted. It can also be applied to cases where separation claws are provided, although they are not. If there is no separation claw and the reverse buckle method is not used, it has no relation to deflection, there is no limit value, and △f
Alternatively, the side-to-side feed ratio is determined by the magnitude of Δμ. That is, the larger △f or △μ is, the larger the double feeding ratio becomes. Based on the above experimental facts, the inventors set △f to 15gr.
As a result of extensive research to reduce △μ to 0.03 or less, we have found that passing individual copies of copy paper between roll nips and applying surface treatment has the effect of making the decrease in △f or △μ more noticeable. I found out the facts. This process can be carried out in the finishing process, for example, as follows. FIG. 2 is a flow sheet showing the flow of paper in the finishing cutting process when carrying out the present invention, using a Rennox cutter as an example. It passes through a roll 3, enters a decurler (curl straightening device) 4, then passes through an expander roll 5 and a lead-in roll 6, and is slit vertically by a slitter knife 7. The slit paper web 1 is held down by pinch rolls 8 and nip rolls 9, cut laterally with a cutter knife 10, and then held between the belts of the paper press top roll 11 and cut into blocks of several sheets (four in the figure). transported. It is presumed that the difference △f between the intralayer friction force and the interlayer friction force or the difference △μ between the intralayer friction coefficient and the interlayer friction coefficient appear due to the pressure applied by the pinch roll 8 and/or the nip roll 9. . The present invention consists in processing the paper by passing it through the roll nip one by one before putting it into the expander roll 5. Therefore, in order to achieve the object of the present invention, each roll nip may be individually provided at an arbitrary location immediately after the decurler 4 is fed out, but it is particularly preferable to install an upper roll 12 on each roll of the decurler 4, and place a roll nip there. If it is formed, it will be outstanding in terms of both effectiveness and economy. The type of roll forming the nip according to the present invention may be any metal roll such as steel or iron, a surface-finished roll plated with chrome or the like, or a rubber roll coated with synthetic or natural rubber. In particular, metal rolls or surface finishing rolls are suitable. Roll surface roughness is JIB B0601
The maximum height (Rmax) specified in 0.1 ^S ~
A range of 100 ^S , especially a range of 1.6 ^S to 25 ^S is preferred.
When using rubber rolls, JIS K6301 is also required.
A hardness of 60 degrees or higher is required.
When installing the roll on the decurler 4, it is preferable that the diameter of the roll be approximately the same as that of the decurler roll.
Good results are obtained in the range of 10-300mm. Further, there is no need to apply pressure to the roll nip, and the process can be carried out using only the roll's own weight, but application of pressure does not hinder the present invention, and the linear pressure is in the range of 0.1 to 20 Kg/cm, particularly 0.5 to 5 Kg/cm. A range of is suitable. There is no particular restriction on the paper passing speed to the roll nip, and it is within the normal operating speed range, i.e. 1 to 600 m/s.
min is used. The surface treatment of paper according to the present invention changes the properties of the paper surface, and even when it is subjected to pressure with pinch rolls 8 and/or nip rolls 9 in a later process, there is no significant difference in surface friction force or coefficient of friction between layers. I won't give it. Further explanation will be given below with reference to Examples. The measurement of frictional force and the double feeding test in the examples were carried out as follows. A set of 4 sample test papers cut into 4 sizes in A row are 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 is applied to the paper. I made it. 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, and the weight is leveled at a speed of 1000 mm/min using a string attached to the tip of the weight. The force was measured using a Tensilon UT model (manufactured by Toyo Baldwin). In this way, 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 frictional force was divided by the weight of the weight (500 gf) to obtain the static friction coefficient, ignoring the weight of the paper. Hereinafter, similar experiments were repeated to measure the intralayer and interlayer frictional forces and friction coefficients, and the average differences were defined as Δf and Δμ, respectively. On the other hand, in a copying machine that prepares a separate pile that has been calendered, uses a reverse buckle system, and also has a separation claw, five sets of blocks do not use the reverse buckle system, but are equipped with a separation claw. A double feeding test was conducted on 50 sets of blocks using a copying machine and a copying machine that did not employ either a reverse buckle or a separation claw. Since double feeding occurs between layers, the results are expressed in terms of the number of times it occurs. Example Add filler (talc) to paper stock of LBKP (350 ml of CSF), size 0.5% (based on pulp), ban sulfate ±0.5% (as Al ₂ O ₃ , based on pulp), and have a basis weight of 64 g/
A paper of m ² was made. The filler addition rate is based on the ash content in the paper.
Oxidized starch was applied at a concentration of 5% using a size press. For reference, the physical properties of the paper obtained are as follows:
64.2g/m ² , thickness 0.086mm, density 0.75g/cm ³ ,
Ash content 5.6%, smoothness ^FS 45sec, WS40sec, Clark stiffness MD18.6cm, CD14.0cm, surface electrical resistance
FS7.2×10 ⁹ Ω, WS7.9×10 ⁹ Ω. This paper was cut into A-row 4-size pieces, and each sheet was passed through a test calendar (made of steel, roll surface length 250 mm, roll diameter 80 mm) without pressure to perform nipping treatment. The linear pressure due to the roll's own weight was 1 Kg/cm. The results of measurements of intralayer and interlayer frictional forces, friction coefficients, and double feed tests were compared for paper with and without surface treatment and are shown in the table.

[Table] As is clear from the table, by lightly surface-treating the paper through a roll nip, a copying machine equipped with a separating claw using the reverse buckle method using 5 sets of blocks, and a reverse buckle machine equipped with a separation claw using 50 sets of blocks were tested. Copying machines that are not buckle-type but equipped with separation claws will never cause double feeding. In these examples, the conditions of Δf<15 and Δμ<0.03 were in good agreement with the results of the actual double-feeding test, and the nip-treated paper was effective in preventing double-feeding. In the case of a copying machine that does not have both a reverse buckle and a separation claw, some double feeding occurs in the 50 block test, but the double feeding ratio in this case is the difference between the intralayer frictional force and the interlayer frictional force △f or It is related only to the difference Δμ between the intralayer friction coefficient and the interlayer friction coefficient, and indicates that double feeding increases when Δf or Δμ is large.

[Brief explanation of the drawing]

Figure 1 shows the double feeding ratio and the difference in frictional force within and between layers (△
f) Or a diagram showing the relationship between the intra-layer and inter-layer differences in friction coefficient (△μ), and Figure 2 is a diagram showing the cutting process in the case where the decurler is provided with an upper roll to form a nip as an example of implementing the present invention. An example of a cutter is shown. In the figure, △f: difference between the intralayer frictional force and the interlayer frictional force,
△μ: Difference between intralayer friction coefficient and interlayer friction coefficient, 1:
Paper web, 2: Fabric stand, 3: Tension roller, 4: Decurler, 5: Expander roll, 6: Lead-in roll, 7: Slitter knife, 8: Pinch roll, 9: Nip roll, 1
0: cutter knife, 11: paper press top roll, 12: upper roll.

Claims (1)

[Scope of Claims] 1. In the finishing process of copy paper, immediately before cutting a plurality of stacked paper webs into small pieces at once, each copy paper is individually passed through a roll nip for surface treatment to reduce static friction within the paper layers. The difference between the coefficient and the interlayer static friction coefficient is
A method for preventing double feeding of copy paper, characterized by reducing the amount to 0.03 or less. 2. A method for preventing double feeding of copying paper according to claim 1, wherein an upper roll is installed on each roll of a paper decurler to perform surface treatment of the paper as a roll nip.