JP5473503B2 - Paper sheet double feed prevention member - Google Patents

Description

  The present invention relates to a paper sheet multi-feed preventing member for separating and feeding a plurality of stacked paper sheets one by one.

  For example, paper sheets stacked and stored in the paper feed cassette or the like in an image forming apparatus such as an electrostatic copying machine, a laser printer, a plain paper facsimile machine, or a multifunction machine thereof are stacked. A paper feed mechanism is provided to prevent the paper from being sent out (double feed) in a state where two or more sheets are mistakenly overlapped. The paper feed mechanism includes a paper feed roller having at least an outer peripheral surface formed of rubber or the like, and a paper sheet multi-feed preventing member disposed so as to be able to contact the outer peripheral surface of the paper feed roller by a pressing force of a spring or the like. It is common to include.

The paper feeding mechanism is configured to prevent the second and subsequent stacked paper sheets from being erroneously conveyed by the frictional force of the paper sheet multi-feed preventing member, and to prevent the first paper contacting the paper feeding roller. Only the paper sheets are separated from the other paper sheets by the rotation of the paper feed roller and sent out.
The paper sheet multi-feed preventing member is formed in a flat plate shape with one surface being a contact surface that comes into contact with a paper feed roller or paper sheet, and at least the contact surface, preferably the entirety thereof is rubber, thermoplastic elastomer, etc. In general, a separation pad, a separation sheet, or the like formed of the above-mentioned elastomer is used (see Patent Documents 1 to 3).

JP-A-5-43070 Japanese Patent No. 3977819 Japanese Patent No. 4,176,592 JP 2005-154601 A JP 2004-11734 A

The flat paper sheet multi-feed prevention member such as the separation pad is required to be less likely to cause a phenomenon called so-called squealing that generates chatter vibrations due to friction with a paper feed roller or paper sheets. . Polyester elastomers, butadiene rubbers, and the like are known as elastomers that can form a paper sheet multi-feed preventing member having excellent characteristics.
However, the paper sheet multi-feed preventing member made of the polyester-based elastomer is formed of a cross-linked product (vulcanized product) formed by crosslinking a rubber compounded with a cross-linking agent (vulcanizing agent) into a flat plate shape. There was a problem that the abrasion resistance was not sufficient as compared with the paper sheet multi-feed preventing member.

Although it was also studied to improve the abrasion resistance by blending polyurethane elastomer with polyester elastomer, the wear resistance of the paper sheet multi-feed prevention member is still the same as the conventional one made of a cross-linked rubber. It was not possible to improve to a certain extent.
Further, the paper sheet multi-feed preventing member made of butadiene rubber can improve the wear resistance as compared with the one made of the polyester-based elastomer and the like because the butadiene rubber is cross-linked by a cross-linking agent like other rubbers. However, paper sheet multi-feed prevention members made of cross-linked butadiene rubber are prone to thermal aging, ozone exposure, or UV exposure, and reliability tests are conducted to confirm these characteristics. There was a problem that the result was insufficient, that is, the reliability was not sufficient.

  In recent years, elastomers obtained by dynamically crosslinking ethylene-propylene-diene rubber (EPDM) in polypropylene (PP), so-called DC material blends, are becoming mainstream as materials for forming paper sheet multi-feed preventing members. The paper sheet multi-feed preventing member made of EPDM / PP type elastomer is not sufficient in abrasion resistance as compared with the conventional one made of a cross-linked rubber.

  An object of the present invention is to provide a paper sheet multi-feed preventing member that is excellent in the effect of preventing noise and has excellent wear resistance and reliability.

As a result of various studies by the inventor to solve the above-described problems, at least the contact surface of the paper sheet multi-feed prevention member that is in contact with the paper sheet is formed of a pre-crosslinked butadiene rubber and subjected to an electron beam irradiation treatment. I found out that I should do it.

That is, at least the contact surface, when the electron beam irradiation treatment so as to form the pre-crosslinked butadiene rubber with a crosslinking agent, the crosslinking degree of the butadiene rubber after treatment, it is increased than with only crosslinking with crosslinking agents Can do.
Therefore, it is possible to specifically improve the reliability while maintaining the effect of satisfactorily preventing noise based on the characteristics of the butadiene rubber and high wear resistance.

Elastomer crosslinking itself by electron beam irradiation is a well-known technique as described in, for example, Patent Documents 4 and 5.
However, by applying an electron beam irradiation treatment to the elastomer that forms at least the contact surface of the paper sheet multi-feed prevention member, the above-mentioned paper sheet weight is maintained while maintaining good characteristics peculiar to each elastomer as described above. It is not described in any patent document that a particularly remarkable effect of improving the wear resistance and reliability of the feeding prevention member can be obtained.

Therefore, the present invention is a paper sheet multi-feed preventing member that constitutes a paper feed mechanism of an image forming apparatus in combination with a paper feed roller, and has one surface as a contact surface that contacts the paper feed roller or paper sheets. is formed in a flat plate shape, at least the contact surface, a preventing member sheet double feed, characterized in that it is pre-crosslinked allowed the Butajiengo arm or Rannahli, electron beam irradiation treatment.

  According to the present invention, it is possible to provide a paper sheet multi-feed preventing member that is excellent in the effect of preventing noise and that is excellent in wear resistance and reliability.

It is a perspective view which shows an example of embodiment of the paper sheet double feed prevention member of this invention. It is a schematic sectional drawing which shows an example of the paper feeding mechanism incorporating the paper sheet double feed prevention member of the example of FIG.

FIG. 1 is a perspective view showing an example of an embodiment of a paper sheet multi-feed preventing member of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a paper feed mechanism incorporating the paper sheet multi-feed preventing member of the above example.
Referring to FIG. 2, a sheet feeding mechanism 1 of this example includes a sheet feeding roller 3 having at least an outer circumferential surface 2 formed of rubber or the like, and an outer circumferential surface of the sheet feeding roller 3 by a pressing force such as a spring (not shown). 2 and a paper sheet multi-feed preventing member (separation pad) 4 disposed so as to be in contact with each other.

  In this example, the paper sheet multi-feed preventing member 4 is formed in a rectangular flat plate shape, and is held by a support base 6 with an upper surface (contact surface) 5 exposed in the figure which is one side thereof. Then, with the contact surface 5 facing the outer peripheral surface 2 of the paper feed roller 3, the support 6 is moved in the direction of the outer peripheral surface 2 by a spring or the like (not shown) as indicated by a white arrow in the figure. The contact surface 5 can be brought into contact with the outer peripheral surface 2 with a predetermined pressure contact force.

  The paper feed mechanism 1 conveys the second and subsequent paper sheets 7 out of a plurality of paper sheets 7 stacked and accommodated in a paper feed cassette or a paper feed tray of the image forming apparatus. Only the first sheet 7 in contact with the paper feed roller 3 is suppressed by the frictional force with the contact surface 5 of the double feed prevention member 4, and the one-dot chain line arrow in the drawing of the paper feed roller 3. The paper sheet 7 is separated from the other paper sheets 7 as it is rotated in the direction indicated by, and is sent out to the inside of the image forming apparatus as indicated by solid arrows in the drawing.

With reference to FIG. 1, the paper sheet multi-feed preventing member 4 of this example is integrally formed in the rectangular flat plate shape by an elastomer as a whole.
As the elastomer, blanking Tajiengo beam having excellent effect of preventing the ringing as described above is used.

The Bed Tajiengomu, blending a crosslinking agent for crosslinking the butadiene rubber. Examples of the crosslinking agent include peroxide crosslinking agents and sulfur.

Further, butadiene rubber includes, for example, bis zinc methacrylate, zinc bis acrylate, bis methacrylic acid in order to improve characteristics such as compression set, high temperature tearing, heat aging performance, and workability of the paper sheet multi-feed preventing member 4. You may mix | blend polyfunctional monomers (co-crosslinking agent) etc., such as magnesium .

The butadiene rubber may contain a filler such as carbon black, calcium carbonate, silica, titanium oxide, or talc in order to adjust the rubber hardness of the paper sheet multi-feed preventing member 4 .

Preventing member 4 feed sheet doubles are prepared by butadiene rubber crosslinking agent, and blended with the above exemplified various additives if necessary, shaping were kneaded to crosslink further electron beam irradiation treatment Is done.

In order to form the paper sheet multi-feed preventing member 4 into the rectangular flat plate shape shown in FIG. 1, for example, the kneaded material is formed into a plate shape or a sheet shape and then cut into a predetermined planar shape (rectangular shape). Alternatively, the kneaded material may be preliminarily filled into a mold and formed into a rectangular flat plate shape.
Bed Tajiengo beam, after molding the kneaded mixture into a plate-like or sheet-like, or after the plate or sheet was cut into a rectangular shape, or after the molding the kneaded material into a rectangular plate shape, and electron beam irradiation treatment to cross-linking by heating prior to the.

The conditions of the electron beam irradiation treatment include the grade of butadiene rubber forming the paper sheet multi-feed preventing member 4 and the structure of the paper sheet multi-feed preventing member 4 (single layer structure or laminated structure of two or more layers). It can be arbitrarily set according to the thickness, etc., or according to the wear resistance, reliability, etc. required for the paper sheet multi-feed preventing member 4.
The contact surface of the paper sheet multi-feed preventing member 4 may be adjusted to a predetermined surface roughness and thickness by performing a polishing process or the like prior to the electron beam irradiation process.

The thickness of the paper sheet multi-feed preventing member 4 is preferably about the same as that of the conventional one in consideration of incorporation into the paper feeding mechanism 1. Although the thickness varies depending on the structure of the sheet feeding mechanism 1 and the structure of the image forming apparatus incorporating the sheet feeding mechanism 1, the thickness is preferably 0.2 mm or more, particularly 0.4 mm or more, and 4 mm or less, particularly 3. It is preferably 5 mm or less.
Further, the hardness of the paper sheet multi-feed preventing member 4 is determined by a measuring method defined in Japanese Industrial Standard JIS K6253: 2006 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Hardness”, and the temperature is 23 ± 1. It is preferably A60 / S or more, particularly preferably A70 / S or more, more preferably A95 / S or less, and particularly preferably A90 / S or less in terms of type A durometer hardness at 55 ° C. and relative humidity 55 ± 1%.

  If the paper sheet multi-feed preventing member 4 has a hardness less than the above range, the contact surface 5 of the paper sheet multi-feed preventing member 4 is too soft and is subjected to the electron beam irradiation treatment. There is a risk of wear due to friction. If the hardness exceeds the above range, the paper sheet multi-feed preventing member 4 becomes hard, and the deformation amount in the thickness direction when the contact surface 5 is brought into contact with the outer peripheral surface 2 of the paper feed roller 3 is small. Tend to be. For this reason, the effect of preventing the multi-feed of the paper sheets is reduced by the frictional force of the contact surface 5, and it becomes impossible to reliably prevent the multi-feed by sufficiently corresponding to various types of paper sheets having different friction coefficients. There is a fear.

In order to adjust the hardness of the paper sheet multi-feed preventing member 4, for example , the grade of butadiene rubber may be selected, or the type and amount of the filler may be adjusted.
The paper sheet multi-feed preventing member 4 can be incorporated into the paper feeding mechanism 1 by being fixed to the support base 6 using, for example, a double-sided adhesive tape, a double-sided adhesive tape, or the like.

Production of the paper sheet multi-feed preventing member, measurement of characteristics, and tests in the following examples and comparative examples were performed in an environment of a temperature of 23 ± 1 ° C. and a relative humidity of 55 ± 1%, unless otherwise specified.
<Example 1>
Butadiene rubber [JSR BR01 manufactured by JSR Co., Ltd.] 100 parts by mass, bis zinc methacrylate 10 parts by mass, calcium carbonate [Shiraishi Hana (registered trademark) CC manufactured by Shiraishi Kogyo Co., Ltd.] 15 parts by mass, silica [Tosoh Silica Nipsil (registered trademark) VN3] 20 parts by mass, carbon black [the above-mentioned seast SO] 1 part by mass, and an organic peroxide crosslinking agent [dicumyl peroxide, Park Mill (manufactured by NOF Corporation) (Registered Trademark) D] 2.5 parts by mass were mixed and kneaded to form a sheet having a thickness of 2.0 mm, and then heated at 160 ° C. for 20 minutes to crosslink the butadiene rubber. Next, an electron beam irradiation treatment was performed, and the sheet was further cut into a rectangular shape and polished to produce a rectangular flat sheet-shaped paper sheet multi-feed preventing member having a thickness of 1.2 mm. The electron beam irradiation dose was 60 kGy. The treatment was performed twice by irradiating the sheet placed on the tray with an electron beam of 30 kGy per time, thereby setting the total irradiation dose to 60 kGy.

<Examples 2 and 3>
Same as Example 1 except that the number of electron beam irradiation treatments was adjusted so that the total irradiation dose was 150 kGy (Example 2, 5 treatments) and 240 kGy (Example 3, 8 treatments). Thus, a paper sheet multi-feed preventing member was produced.
<Comparative example 1>
The sheet before the electron beam irradiation treatment prepared in Example 1 was cut out into a rectangular shape and polished to obtain a rectangular flat sheet-shaped paper sheet multi-feed preventing member having a thickness of 1.2 mm.

<Hardness measurement>
The type A durometer hardness of the paper sheet multi-feed preventing member produced in the above-mentioned Examples and Comparative Examples was measured by the measurement method defined in the above-mentioned JIS K6253: 2006.
<Measurement of friction coefficient>
A surface property measuring machine is used to measure the coefficient of friction of the surface of the paper sheet multi-feed preventing member manufactured in the above-mentioned Examples and Comparative Examples with respect to plain paper (PB PAPER manufactured by Canon Inc.) as a measuring paper. [Measured using Tribogear (registered trademark) type HEIDON (Haydon, (registered trademark) -14DR) manufactured by Shinto Kagaku Co., Ltd.] The measurement conditions were the size in the surface direction of the paper sheet multi-feed preventing member: 10 mm × 30 mm, load: 1.96 N (= 200 gf), speed: 600 mm / min.

<Measurement of swelling rate>
The mass (g) before and after immersing the paper sheet multi-feed preventing member produced in the Examples and Comparative Examples in toluene maintained at a liquid temperature of 23 ± 1 ° C. for 24 hours was measured. And the following formula (1):
Swelling ratio (mass%) = [mass after immersion (g)] / [mass before immersion (g)] × 100 (1)
Thus, the swelling ratio (% by mass) after immersion was determined. The presence or absence of crosslinking of the elastomer forming the paper sheet multi-feed prevention member and the degree of crosslinking can be estimated from the amount of swelling. That is, it can be estimated that the smaller the swelling amount, the higher the degree of crosslinking.

<Measurement of wear amount>
After measuring the initial mass (g) of the paper sheet multi-feed prevention member produced in the above-mentioned Examples and Comparative Examples, the paper sheet multi-feed prevention member was used as a monochrome laser printer [LBP-1420 manufactured by Canon Inc.]. Install it instead of a genuine separation pad.
The mass after passing 30000 PPC sheets continuously (mass after passing) (g) was measured, and the difference from the initial mass was determined as the wear amount to evaluate the wear resistance.

The results are shown in Table 1.

From the results shown in Table 1 , in the system using butadiene rubber cross-linked in advance as an elastomer, the degree of cross-linking of the butadiene rubber is increased by electron beam irradiation treatment, and the hardness and friction coefficient are hardly changed. It was found that the wear resistance can be improved and that the wear resistance can be further improved by increasing the degree of crosslinking as the electron beam irradiation dose is increased.
In addition, the following reliability test was also performed on the paper sheet multi-feed preventing member manufactured in the above-mentioned Examples and Comparative Examples.

<Heat aging test>
The paper sheet multi-feed preventing member produced in the examples and comparative examples is housed in an oven set at a temperature of 100 ° C., taken out from the oven after 4 days, 8 days, and 15 days, respectively, and the friction described above. The coefficient was measured.
<Ozone exposure test>
The paper sheet multi-feed preventing member produced in Examples and Comparative Examples was left in an environment having an ozone concentration of 50 ppm and a temperature of 40 ° C. and taken out from the environment after 2 days, 8 days, and 15 days, respectively. The coefficient of friction described above was measured.

<UV exposure test>
The paper sheet multi-feed prevention member produced in the examples and comparative examples was exposed to ultraviolet rays emitted from a carbon arc lamp having an output of 150 W / mm ² in an environment of a temperature of 63 ° C., and after 24 hours, 48 hours, and 72 hours, respectively. It was taken out from the environment and the coefficient of friction described above was measured.

The results are shown in Tables 2 to 4 together with the measured values of the coefficient of friction in Table 1 , which are initial values before each test.

From the results of Table 2 to Table 4 , in the system using butadiene rubber cross-linked in advance as an elastomer, the degree of cross-linking of the butadiene rubber is increased by electron beam irradiation treatment, and deterioration due to heat aging or ozone exposure, Alternatively, deterioration due to ultraviolet exposure is less likely to occur and the reliability of the paper sheet multi-feed prevention member can be improved, and the degree of crosslinking can be increased as the electron beam irradiation dose is increased to further improve the reliability. understood.

DESCRIPTION OF SYMBOLS 1 Paper feed mechanism 2 Outer peripheral surface 3 Paper feed roller 4 Paper sheet double feed prevention member 5 Contact surface 6 Support stand 7 Paper sheet

Claims (1)

A paper sheet multi-feed preventing member that forms a paper feed mechanism of an image forming apparatus in combination with a paper feed roller, and is formed in a flat plate shape with one surface serving as a contact surface that contacts the paper feed roller or paper sheets. Rutotomoni, at least the contact surface, preliminarily crosslinked allowed the Butajiengo arm or Rannahli paper sheet multi-feed prevention member, characterized in that it is an electron beam irradiation treatment.

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