JPH075200B2 - Rubber member for paper feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber member for a sheet feeding device, and more particularly, to an improvement of a double feed preventing rubber pad or a rubber roller in a sheet feeding device such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art In a sheet feeding device such as a copying machine, a facsimile or a printer, a sheet feeding roller (see FIG. 1) is used to feed a large number of sheets set in a cassette one by one. A member (2) such as a double feed prevention rubber pad or a rubber roller is provided so as to face 1). Note that FIG. 1 illustrates a rubber pad as the double feed preventing rubber member (2).

Conventionally, urethane, a combination of urethane and cork, natural rubber, chloroprene and the like having excellent wear resistance have been used as the double feed preventing rubber member (2).

[0004]

By using the paper feed roller (1) and the double feed preventing rubber member (2), as shown in FIG.
As shown in Fig. 4, in order to smoothly feed a large number of paper sheets (3) (3) set in a cassette or the like one by one, the friction coefficient between the members is expressed by the following formula 1. Need to be satisfied.

Μ _F > μ _R > μ _p Equation 1

Here, μ _F is the coefficient of friction between the paper feed roller (1) and the paper sheets (3), and μ _R is the coefficient of friction between the double feed preventing rubber member (2) and the paper sheets (3). , Μ _p are friction coefficients between the paper sheets (3), (3), ...

The above relationship must be maintained even when at least 100,000 sheets have been passed. Therefore, as a result of measuring μ _F and μ _P with the currently used member,
Since μ _P is 0.3 to 0.6 and μ _F is 1.5 to 2.5, μ _R is preferably 0.7 to 1.2. In the case of OHP (overhead projector) film, μ _P is
0.3-1.5 and μ _F is 2.5-3.0, so μ _R
1.7 to 2.4 is preferable.

However, as a problem of the conventional urethane, the combination of urethane and cork, the double feed preventing rubber member (2) made of natural rubber, chloroprene, etc., the friction coefficient is caused by the adhesion of paper dust generated when the plain paper is fed. descend.
The initial friction coefficient is large (it becomes an appropriate friction coefficient after 5,000 to 10,000 sheets have been passed), and it is particularly difficult to feed the OHP film. When sending coated paper, OHP film, etc., an abnormal sound called squeal occurs.
The paper feed roller (1) used facing each other has recently been used.
Polynorbornene-based rubber is often used, and this rubber contains 100 to 100 parts by weight of process oil per 100 parts by weight of polymer.
Since it contains 250 parts by weight, when a mechanism for constantly contacting the paper feed roller (1) is adopted, deformation due to swelling and an increase in friction coefficient become problems.

The present invention was developed as a result of various studies and studies in view of the above conventional problems. The purpose of the present invention is that the friction coefficient is stable for a long period of time, and abnormal noise is generated during sheet feeding. Another object of the present invention is to provide a rubber member for a sheet feeding device that is free from swelling and that swells less when contacting the sheet feeding roller.

[0010]

[Means for Solving the Problems] For the above problems,
As a rubber composition to which paper powder is unlikely to adhere, a rubber composition obtained by blending a metal oxide and acrylic acid and applying it has been found.

With the above rubber composition, it is difficult for paper powder to adhere and a stable friction coefficient can be obtained for a long period of time, but the initial friction coefficient is large and the friction coefficient changes as shown in FIG.
Therefore, it is suitable for a sheet feeding device that does not use a paper sheet having a large friction coefficient with rubber such as an OHP film, but when the OHP film must be sent, the relation of Formula 1 is broken. Smooth feed cannot be achieved. Therefore, in the present invention, from the results of experiments, in view of the above problems, it is possible to add short fibers to the above rubber composition to reduce the initial friction coefficient, and to gradually abrade with passing paper. It was found that the effect of lowering the coefficient of friction can be kept only at the initial stage by selecting the thickness and length of various fibers (see the experimental data in FIGS. 3 to 14). The thickness of the short fibers is preferably 15 denier or less. When it exceeds 15 denier, the fibers are hard to wear and the coefficient of friction becomes too low. Moreover, it is desirable that the length of the short fibers is 5 mm or less. If it exceeds 5 mm, the fibers will not be easily worn away, and the coefficient of friction will be too low.
The material of the short fibers is not particularly limited, but 140
Since it is heated to ~ 190 ° C, it must have a melting point above the reaction temperature. The optimum amount of the short fibers added is 0.5 to 5 parts by weight based on 100 parts by weight of the polymer. Here, the amount of short fibers added was set to 0.5 to 5 parts by weight with respect to 100 parts by weight of the polymer, because when the amount exceeds 5 parts by weight, abrasion is delayed and the friction coefficient is not stable. The decrease in the friction coefficient is small, and the friction coefficient becomes unstable. Thus, by adding 0.5 to 5 parts by weight of short fibers having a denier of 15 or less to 100 parts by weight of the polymer, as shown in FIG. 15, a rubber member for a paper feeder having a stable friction coefficient from the initial stage to a long period of time. Can be obtained.

In this way, a rubber member for a sheet feeding device exhibiting a stable friction coefficient can be obtained. However, the friction coefficient must be adjusted to an optimum value depending on the type and design (load, mounting method) of the sheet feeding device. I have to. If the coefficient of friction is too large, squeal occurs on the OHP film or coated paper, and if the coefficient of friction is too low, double feed occurs. Therefore, in the present invention, it has been found that short fibers can be mixed as needed to adjust the friction coefficient. That is, the short fibers are exposed on the surface, and due to the appropriate frictional resistance due to the exposed short fibers, the squeaking of the OHP film or the coated paper can be prevented, and the double feeding can be prevented.

Next, to solve the problems, it is considered to make the polymer oil resistant. However, since the higher the oil resistance of the polymer, the more likely it is that the problem of squealing will occur, it is necessary to select one of the oil resistant rubbers that is hard to squeal and to achieve both the oil resistance and the difficulty of squealing, which are contradictory properties. is there. Therefore, from the results of the experiment, when the test piece was immersed for 48 hours at 40 ° C. in oil mixed with polynorbornene-based rubber that is often used for the paper feed roller, and the volume increase rate due to swelling was 10% or less, It has been found that it can have oil resistance without impairing the performance of the double feed preventing rubber member. Further, in consideration of the problems, it was found that among the oil resistant rubbers, an acrylonitrile-butadiene copolymer rubber (hereinafter referred to as NBR), which is the most difficult to squeal and has a large degree of freedom in compounding, is suitable. By the way, there are various grades of commercially available NBR, but in order to solve the problems and the problems, NBR
It is necessary to select a simple substance, a mixture of NBRs having different acrylonitrile contents, or a polymer of a mixture of NBR and a diene rubber so that the bound acrylonitrile content of the polymer is 10 to 35%. Here, the diene rubber refers to NR (natural rubber), IR (isoprene rubber), SBR (styrene-butadiene rubber), BR (butadiene rubber), IIR (butyl rubber), CR (chloroprene rubber), and NBR. The reason why the bound acrylonitrile content is preferably 10 to 35% is that if it is less than 10%, the oil resistance cannot be satisfied, and if it exceeds 35%, the glass transition point becomes high and it tends to squeal. In order to obtain the bound acrylonitrile content of 10 to 35%, NBR alone, a mixture of NBRs, and a mixture of NBR and a diene rubber may be selected so as to achieve the bound acrylonitrile content. Also, when ozone resistance is required depending on the model, EPDM with excellent ozone resistance
(Ethylene-propylene diene rubber) may be mixed.

[0014]

According to the present invention, some of the short fibers exposed on the surface of the rubber member moderately reduce the excessive surface friction coefficient at the initial stage of paper feeding, and the fibers gradually wear as the paper is fed, so that an appropriate friction is obtained. The coefficient can be maintained. The oil resistant rubber has excellent oil resistance and can suppress swelling from the paper feed roller. Further, by mixing the cork, the friction coefficient can be adjusted to obtain an appropriate surface friction resistance. In addition, oil resistant rubber is combined with acrylonitrile content of 10 ~ 35%
Since it is a simple substance of NBR or a mixture thereof with a diene rubber, it can be made difficult to squeal while having oil resistance. Further, by mixing acrylic acid and metal oxide, it is possible to prevent paper dust from adhering. Needless to say, the present rubber member can be used to form a roller, and the roller can be used as a separation roller for discharging and feeding paper between the rollers.

[0015]

Embodiments of the present invention will be described below.

A double feed preventing rubber member was formed from the rubber composition obtained by adding the compounds of Examples A to X shown in Table 1 below, and in the case of plain paper and OHP film, 1000 sheets were initially fed. The coefficient of friction was measured after and after passing 100,000 sheets. The results are also shown in Table 1.

[0017]

[Table 1]

[0018]

As described above, the rubber member of the present invention has a stable friction coefficient for a long period of time, does not cause abnormal noise during paper feeding, and is excellent in oil resistance. Little swell even if it is in constant contact with the rubber feed roller. Therefore, it is possible to provide a highly reliable and high quality rubber member for a paper feeding device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a sheet feeding device.

FIG. 2 is a diagram showing a change in friction coefficient in a rubber composition in which a metal compound and acrylic acid are mixed.

[Figure 3] Length is 3mm, thickness is 2 denier, 7 denier,
FIG. 4 is a graph showing the relationship between the acrylonitrile content at the initial stage of paper feeding and the friction coefficient of plain paper in each rubber composition containing short fibers different from 15 denier and 20 denier.

[Fig. 4] Length is 5mm, thickness is 2 denier, 7 denier,
FIG. 4 is a graph showing the relationship between the acrylonitrile content at the initial stage of paper feeding and the friction coefficient of plain paper in each rubber composition containing short fibers different from 15 denier and 20 denier.

[Figure 5] Thickness is 2 denier, 7 denier, 15 denier,
FIG. 3 is a graph showing the relationship between the acrylonitrile content at the beginning of paper feeding and the friction coefficient of the OHP film in each rubber composition containing 20 denier and different short fibers each having a length of 3 mm.

[Figure 6] Thickness is 2 denier, 7 denier, 15 denier,
FIG. 3 is a graph showing the relationship between the acrylonitrile content at the initial stage of paper feeding and the friction coefficient of the OHP film in each rubber composition containing 20 denier and short fibers each having a different length of 5 mm.

FIG. 7: Short fiber content 0.3 phr, thickness 2 denier, 7
FIG. 3 is a graph showing a change in friction coefficient of plain paper in each rubber composition in which short fibers each having a length of 5 mm, which are different from denier, 15 denier, and 20 denier, are mixed.

FIG. 8: Short fiber content 0.5 phr, thickness 2 denier, 7
FIG. 3 is a graph showing a change in friction coefficient of plain paper in each rubber composition in which short fibers each having a length of 5 mm, which are different from denier, 15 denier, and 20 denier, are mixed.

Fig. 9 Short fiber content is 3 phr and thickness is 2 denier, 7 denier, 15 denier, 20 denier and different lengths.
It is a figure which shows the change of the friction coefficient of the plain paper in each rubber composition which mix | blended the 5 mm short fiber.

[Fig. 10] Short fiber content is 5 phr and thickness is 2 denier, 7 denier, 15 denier, 20 denier, and different lengths.
It is a figure which shows the change of the friction coefficient of the plain paper in each rubber composition which mix | blended the 5 mm short fiber.

[Figure 11] Short fiber content is 0.3 phr, thickness is 2 denier, 7
OH in each rubber composition containing denier, 15 denier, and 20 denier short fibers each having a different length of 5 mm
It is a figure which shows the change of the friction coefficient of the film for P.

[Fig.12] Short fiber content is 0.5 phr, thickness is 2 denier, 7
OH in each rubber composition containing denier, 15 denier, and 20 denier short fibers each having a different length of 5 mm
It is a figure which shows the change of the friction coefficient of the film for P.

Fig. 13 Short fiber content is 3 phr and thickness is 2 denier, 7 denier, 15 denier, 20 denier and different lengths.
OHP in each rubber composition blended with 5 mm short fiber
It is a figure which shows the change of the friction coefficient of the film for films.

[Figure 14] Short fiber content is 5 phr and thickness is 2 denier, 7 denier, 15 denier, 20 denier, and different lengths.
OHP in each rubber composition blended with 5 mm short fiber
It is a figure which shows the change of the friction coefficient of the film for films.

FIG. 15 is a diagram showing a change in a friction coefficient in the rubber member for the paper feeding device of the present invention.

[Explanation of symbols]

 1 Paper feed roller 2 Double feed prevention rubber member 3 Paper sheets

Claims (5)

[Claims] 1. 0.5 to 5 parts by weight of short fibers having a thickness of 15 denier or less and a length of 5 mm or less are mixed with 100 parts by weight of a polymer, and a part of the short fibers is exposed on the surface of a rubber member. A rubber member for a paper feeder. 2. The rubber member for a sheet feeding device according to claim 1, wherein the polymer is oil resistant rubber. 3. The rubber member for a sheet feeding device according to claim 1, wherein cork is mixed in the polymer. 4. The oil resistant rubber is composed of an acrylonitrile-butadiene copolymer rubber alone or in a mixture with another predetermined rubber, and has a bound acrylonitrile content of 10 to 35%. Item 2. A rubber member for a sheet feeding device. 5. The bound acrylonitrile content of 10-35.
The rubber member for a sheet feeding device according to claim 4, wherein acrylic acid and a metal oxide are mixed in the oil resistant rubber (%).