JP2000319445A - Rubber composition and paper sending roller using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the workability of a paper sending roller 1 while keeping its high paper sending ability and to reuse a large amount of polishing powder generated in the production process of the paper sending roller 1. SOLUTION: A paper sending roller 1 is molded from a rubber composition. The rubber composition contains 100 pts.wt. of a crude rubber and not less than 5 pts.wt. and not more than 30 pts.wt. of a crosslinked rubber powder. The average particle size of the crosslinked rubber powder is not less than 1 μm and not more than 500 μm. A preferable crosslinked rubber powder is a polishing powder generated in the production process of the paper sending roller 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a paper feed roller mounted on OA equipment and the like, and to a paper feed roller using the rubber composition.

[0002]

2. Description of the Related Art Copiers, facsimile machines, printers, A
A paper feed roller (referred to as a paper feed roller, a transport roller, a paper discharge roller, etc.) is used for a paper feed mechanism, a paper transport mechanism, a paper discharge mechanism, and the like of an electrophotographic apparatus such as a TM. Since the paper feed roller feeds paper, film, and the like, a high coefficient of friction with paper or the like is required. Normally, rubber such as EPDM, natural rubber, urethane rubber, chloroprene rubber, and polynorbornene is used for the paper feed roller, which imparts flexibility to the paper feed roller and increases the coefficient of friction with paper. I have. Among these rubbers, EPDM, whose main chain is made of a chemically stable saturated hydrocarbon and which is hardly deteriorated by molecular main chain cleavage even when exposed to high concentration ozone for a long time, is particularly preferably used. ing.
This is because the use of EPDM imparts ozone resistance to the paper feed roller and suppresses ozone deterioration of the paper feed roller even when the paper feed roller is mounted on an electrophotographic apparatus that generates ozone during formation of an electrostatic latent image.

[0003] Generally, fillers are often compounded in rubber compositions. The processability of the rubber composition is improved by the addition of the filler. Specifically, for example, the extrusion speed during extrusion molding is increased. When the filler is inexpensive, it functions as a kind of extender, and the material cost of the rubber molded article can be reduced. A typical filler is carbon black. However, since the paper feed roller comes into contact with the paper, a large amount of carbon black which may stain the paper is not blended. For this reason, so-called white fillers such as silica, calcium carbonate, titanium oxide, and talc are often compounded in the paper feed roller.

[0004]

However, as the amount of the filler increases, the hardness of the paper feed roller increases, the friction coefficient with the paper decreases, and the paper feed performance deteriorates. For this reason, the actual condition is that the compounding amount of the filler is suppressed, the processability (that is, productivity) is sacrificed to some extent, and the paper feeding performance is maintained. In particular, since the above-mentioned EPDM is a rubber having inferior processability, the problem of a decrease in processability when the content of the filler is suppressed is serious.

[0005] The paper feed roller is often manufactured by extruding a rubber composition with an extruder to form a preform and then cross-linking the preform with a vulcanizer. In this manufacturing method, the dimensional accuracy of the paper feed roller is hard to be obtained as compared with the die molding method or the like. For this reason, the preform is formed larger than the size of the target paper feed roller, and the preform is polished after crosslinking. The desired dimensions are obtained by polishing, and the surface roughness of the paper feed roller is adjusted. In the polishing process, a large amount of polishing powder is generated and is treated as industrial waste. In today's growing interest in resource conservation,
Reuse of the abrasive powder is being considered.

The present invention has been made in view of such circumstances, and has as its object to improve the workability of a paper feed roller while maintaining a high paper feed performance. Another object of the present invention is to reuse a large amount of abrasive powder generated in a paper feed roller manufacturing process.

[0007]

Means for Solving the Problems The invention made to achieve the above object contains raw rubber and 5 to 30 parts by weight of a crosslinked rubber powder based on 100 parts by weight of the raw rubber. The crosslinked rubber powder has an average particle diameter of 1
a rubber composition for a paper feed roller having a size of not less than μm and not more than 500 μm.

This rubber composition is excellent in processability since a crosslinked rubber powder is blended as a filler, and the extrusion speed at the time of extrusion is increased. In addition, since the filler itself is rubber and has properties similar to those of the matrix rubber, an increase in the hardness of the paper feed roller obtained from this rubber composition can be suppressed even if the filler is mixed in a large amount to some extent. For this reason, the coefficient of friction between the paper feed roller and the paper hardly decreases, and the paper feed performance of the paper feed roller is maintained.

In the present invention, if the crosslinked rubber powder is an abrasive powder generated in the paper feed roller manufacturing process, the characteristics of the filler and the matrix are more similar, and the increase in the hardness of the obtained paper feed roller is further suppressed. . Further, since the abrasive powder, which is essentially waste, is reused, the material cost of the paper feed roller is reduced, and resource saving is achieved. Further, since the amount of discarded abrasive powder is reduced, the amount of harmful gas generated by, for example, incineration is reduced, and the deterioration of the global environment is suppressed.

In the present invention, if the raw rubber contains 20% by weight or more of EPDM, the weather resistance of the obtained paper feed roller is enhanced and ozone deterioration is suppressed. Further, in the present invention, the EPD containing 20% by weight or more of the crosslinked rubber powder
When M is contained, the weather resistance of the obtained paper feed roller is increased, and ozone deterioration is suppressed. If the raw rubber and the crosslinked rubber powder both contain EPDM as a main component, the characteristics of the filler and the matrix become very similar, and the increase in hardness of the obtained paper feed roller can be further suppressed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings as appropriate. FIG. 1 is a perspective view showing a paper feed roller 1 according to one embodiment of the present invention together with a shaft core 2. The paper feed roller 1 is formed by molding and crosslinking a rubber composition. The paper feed roller 1 is fixed to the shaft core 2 by press-fitting the paper feed roller 1 into the shaft core 2 or by joining both with an adhesive.

The rubber which is the main component of the rubber composition used in the paper feed roller 1 includes EPDM, natural rubber, urethane rubber, chloroprene rubber, polynorbornene, butadiene rubber, isoprene rubber and the like. Are used alone or in combination of two or more. Among these rubbers, EPDM is particularly preferred. E
PDM has a main chain composed of a saturated hydrocarbon and does not contain a double bond in the main chain. For this reason, even when exposed to an environment such as a high-concentration ozone atmosphere or light irradiation for a long time, the molecular main chain is hardly broken. Therefore, the weather resistance of the obtained paper feed roller 1 can be improved. EPDM includes a non-oil-extended type EPDM consisting of only a rubber component and an oil-extended type EPDM containing a confidential oil together with a rubber component, and any type of rubber composition of the present invention can be used. It is.
When an oil-extended EPDM is used, only the rubber component excluding the confidential oil is referred to as “raw rubber” in the present specification.

When EPDM and another rubber are mixed,
The proportion of EPDM in the total raw rubber is preferably at least 20% by weight, particularly preferably at least 50% by weight. If the EPDM ratio is less than the above range, the weather resistance of the obtained paper feed roller 1 may be reduced.

[0014] The rubber composition contains a crosslinked rubber powder. The crosslinked rubber powder functions as a filler in the rubber composition and increases the extrusion rate of the rubber composition. The commonly used inorganic filler increases the hardness of the paper feed roller 1 and lowers the friction coefficient between the paper feed roller 1 and the paper. However, the filler of the crosslinked rubber powder has the same characteristics as the rubber as the matrix. Because they are similar, paper feed roller 1
Changes in the physical properties of the material. That is, the increase in hardness of the paper feed roller 1 is suppressed, and the decrease in the coefficient of friction is suppressed.
Various properties such as abrasion resistance are also maintained.

The compounding amount of the crosslinked rubber powder must be 5 to 30 parts by weight, and preferably 10 to 20 parts by weight, based on 100 parts by weight of the raw rubber. If the amount is less than the above range, the extrusion rate of the rubber composition may be reduced. Conversely, if the compounding amount exceeds the above range, the kneading time of the rubber composition may be prolonged.

The average particle diameter of the crosslinked rubber powder must be 1 μm or more and 500 μm or less, especially 5 μm or more and 10 μm or less.
It is preferably 0 μm or less. If the average particle diameter is less than the above range, the crosslinked rubber powder may be too fine and difficult to handle. Conversely, if the average particle diameter exceeds the above range, the crosslinked rubber powder is unevenly distributed without being dispersed in the rubber composition.
May be uneven in physical properties. The average particle diameter is determined by measuring the particle diameters of 100 randomly extracted crosslinked rubber powders by microscopic observation and averaging them. In the case of a non-spherical crosslinked rubber powder, the diameter of a circle circumscribing the crosslinked rubber powder is defined as the particle diameter. Preferably, the rubber composition of the present invention does not contain any crosslinked rubber powder having a particle diameter exceeding 500 μm.

The crosslinked rubber powder to be compounded is EPD
Those containing M at least 20% by weight, particularly at least 50% by weight are preferred. If the EPDM ratio is less than the above range, the weather resistance of the obtained paper feed roller 1 may be reduced.

A particularly preferred crosslinked rubber powder is an abrasive powder generated in the manufacturing process of the paper feed roller 1. Paper feed roller 1
Is subjected to surface polishing after crosslinking for the purpose of size adjustment, surface roughness adjustment, and the like. At this time, a large amount of polishing powder is generated. The paper feed roller 1 containing this abrasive powder as a filler is:
Since the filler and the matrix are almost the same substance,
The physical properties of the paper feed roller 1 hardly change due to the blending of the crosslinked rubber powder. In particular, if the article number of the paper feed roller 1 to be polished matches the article number of the paper feed roller 1 in which the abrasive powder generated by this polishing is mixed, the composition of the abrasive powder and the rubber containing this abrasive powder The composition of the composition is almost completely the same except for the history of the polishing powder.

When the paper feed roller 1 is polished, polishing conditions such as the number of the grindstone, the number of revolutions of the grindstone, the number of revolutions of the paper feed roller 1 and the feed speed are adjusted, so that the average particle diameter of the abrasive powder is adjusted as described above. Within the preferred range.

The rubber composition of the present invention may further contain a filler other than the crosslinked rubber powder. Examples of the filler that can be blended include carbon black, silica, calcium carbonate, titanium oxide, and talc. Further, a softening agent such as an oil or a plasticizer may be added to the rubber composition of the present invention for the purpose of improving processability, adjusting hardness, and the like. Examples of oils to be blended include paraffinic mineral oils, naphthenic mineral oils, aromatic mineral oils, and synthetic oils composed of hydrocarbon oligomers. In addition, as a plasticizer to be blended, dioctyl phthalate, dibutyl phthalate, dioctyl sepate,
Dioctyl adipate and the like. Further, additives such as a crosslinking aid, a reinforcing agent, a deterioration inhibitor, and a coloring agent may be added to the rubber composition of the present invention as needed.

[0021]

EXAMPLES Hereinafter, the effects of the present invention will be clarified based on examples, but it is needless to say that the present invention should not be construed as being limited based on the description of the examples.

[Reference Example] EPDM rubber (trade name “Esprene 670F” of Sumitomo Chemical Co., Ltd.) 200% oil-extended 200
Parts by weight (100 parts by weight of rubber), 5 parts by weight of zinc oxide (manufactured by Mitsui Mining & Smelting Co., Ltd.), 1.5 parts by weight of sulfur (manufactured by Tsurumi Chemical Co., Ltd.), vulcanization accelerator (trade name of Ouchi Shinko Chemical Co., Ltd.) 1.5 parts by weight of “Noxeller TET”) and 0.5 part by weight of another vulcanization accelerator (trade name “Noxeller M” of Ouchi Shinko Chemical Co., Ltd.) are put into a closed kneader, and kneaded at 120 ° C. Thus, a rubber composition of a reference example was obtained. This rubber composition was put into an extruder and extruded under the conditions of a temperature of 50 ° C. and a head pressure of 50 kgf to obtain a cylindrical molded body. The outer diameter of this molded body is 22m
m, the inner diameter was 8.5 mm, and the length was 300 mm. This molded body was mounted on a vulcanization core having an outer diameter of 9 mm, and charged into a vulcanization can. The crosslinked body was crosslinked at a crosslinking temperature of 160 ° C. for a crosslinking time of 30 minutes to obtain a crosslinked body. This crosslinked body was mounted on a polishing core having an outer diameter of 10 mm, and polished with a cylindrical grinder until the outer diameter became 20 mm. Then, the sheet was cut into a length of 20 mm with a lathe to obtain a paper feed roller.

[Preparation of Abrasive Powder] Abrasive powder generated in the step of polishing the surface of the crosslinked body of the paper feed roller of the reference example was collected.
This abrasive powder was classified with a sieve to obtain an abrasive powder A having a particle diameter of 10 to 50 μm, an abrasive powder B having a particle diameter of 400 to 500 μm, and an abrasive powder C having a particle diameter of 700 to 800 μm.

[Example 1, Example 2, Comparative example 1 and Comparative example 2] Same as the reference example except that the above-mentioned abrasive powder A was further blended and the blending amount was as shown in Table 1 below. Thus, the rubber compositions of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 and a paper feed roller were obtained.

[Example 3, Example 4, Comparative example 3 and Comparative example 4] The same as the reference example except that the above-mentioned abrasive powder B was further compounded and the compounding amount was as shown in Table 1 below. Thus, the rubber compositions of Example 3, Example 4, Comparative Example 3, and Comparative Example 7 and a paper feed roller were obtained.

[Comparative Example 5 and Comparative Example 6] The above polishing powder C
The rubber compositions of Comparative Examples 5 and 6 and a paper feed roller were obtained in the same manner as in Reference Example, except that the amounts were as shown in Table 2 below.

Comparative Examples 7 and 8 The same as the reference example except that silica (Nipsil VN3, trade name of Nippon Silica Co., Ltd.) was further compounded and the compounding amount was as shown in Table 2 below. Thus, the rubber compositions of Comparative Examples 7 and 8 and a paper feed roller were obtained.

[Comparative Examples 9 and 10] Same as Reference Example except that process oil (trade name “PW90” of Idemitsu Kosan Co., Ltd.) was further compounded and the compounding amount was as shown in Table 2 below. Thus, the rubber compositions of Comparative Examples 9 and 10 and a paper feed roller were obtained.

[Measurement of Kneading Time] At the time of kneading with the above-mentioned closed kneader, the kneading time until it was visually determined that the kneading was sufficient was measured. The results are shown in Tables 1 and 2 below.

[Measurement of t _C (90)] Each rubber composition was subjected to JIS.
Subjected to a “vulcanization test using a vibration type vulcanization tester” (curast test) in accordance with K-6300, and a 90% vulcanization time t
_C (90) was determined. The test temperature was 160 ° C and the amplitude angle was 1
゜The results are shown in Tables 1 and 2 below.

[Measurement of Extrusion Time] The extrusion speed at the time of extruding the molded body by the aforementioned extruder was measured. The results are shown in Tables 1 and 2 below.

[Measurement of Hardness] Each rubber composition was cross-linked by an electric press to prepare a block-shaped test piece having a length of 30 mm, a width of 60 mm and a thickness of 12 mm. Crosslinking temperature of 160 ° C,
The crosslinking time was 30 minutes. Using this test piece, the hardness was measured with a durometer hardness tester (type A).
The results are shown in Tables 1 and 2 below.

[Paper Passing Test] Each paper feed roller was attached to a shaft made of synthetic resin and attached to an electrophotographic copying machine. Under the conditions of a temperature of 23 ° C. and a humidity of 55%, a load of 250 g was applied to 10,000 x A4 size PPC paper of Fuji Xerox Co., Ltd.
The sheets were passed for 5 hours. The weight of the paper feed roller was measured before and after the paper was passed, and the difference was defined as the amount of wear. Further, the friction coefficient between the paper feed roller and the paper before and after the paper passing was measured. In the measurement of the coefficient of friction, first, as shown in FIG. 2, an A4-size PPC paper 5 of Fuji Xerox Co., Ltd. connected to a load cell 4 is sandwiched between a paper feed roller 1 and a plate 3, And the paper feed roller 1 was pressed against the plate 3. Next, under the conditions of a temperature of 23 ° C. and a humidity of 55%, the paper feed roller 1 was rotated at a peripheral speed of 300 mm / sec in a direction indicated by an arrow R in FIG. Then, the force (g) generated in the direction indicated by the white arrow F in FIG.
f) was measured, and a value obtained by dividing the force F by the load W was obtained and defined as a friction coefficient. The results are shown in Tables 1 and 2 below.

[0034]

[Table 1]

[0035]

[Table 2]

Appropriate values for each evaluation item in Tables 1 and 2 are as follows: kneading time is less than 10 minutes, t _C (90) is less than 10 minutes, extrusion speed is 0.6 m / min or more, hardness is 35 or less, friction The coefficient is 1.5 or more, and the wear amount is 40 g or less. Note that the rubber compositions of Comparative Examples 5 and 6 were not subjected to subsequent evaluations because a poor dispersion was clearly observed at the kneading stage. From Tables 1 and 2, it can be seen that the rubber compositions of the respective examples show appropriate values in all evaluation items. The evaluation results confirmed the superiority of the present invention.

[0037]

As described above, according to the present invention,
High paper feed performance and workability of the paper feed roller are compatible. Further, according to the present invention, a large amount of abrasive powder generated in the paper feed roller manufacturing process can be reused.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a paper feed roller according to an embodiment of the present invention together with a shaft core.

FIG. 2 is a schematic front view showing a state of friction coefficient measurement.

[Explanation of symbols]

 1 Paper feed roller 2 Shaft core 3 Plate 4 Load cell 5 PPC paper

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (5)

[Claims] 1. A paper comprising raw rubber and 5 to 30 parts by weight of a crosslinked rubber powder based on 100 parts by weight of the raw rubber, wherein the average particle diameter of the crosslinked rubber powder is 1 to 500 μm. Rubber composition for feed rollers. 2. The rubber composition for a paper feed roller according to claim 1, wherein the crosslinked rubber powder is an abrasive powder generated in a paper feed roller manufacturing process. 3. The rubber composition for a paper feed roller according to claim 1, wherein the raw rubber contains EPDM, and a ratio of EPDM to total raw rubber is 20% by weight or more. 4. The paper feed roller according to claim 1, wherein the crosslinked rubber powder contains EPDM, and the ratio of EPDM to the total crosslinked rubber powder is 20% by weight or more. Rubber composition. 5. A paper feed roller using the rubber composition for a paper feed roller according to any one of claims 1 to 4.