JP3330302B2 - Rubber composition containing EPDM polymer as main component and rubber roller using the same - 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 composition containing an EPDM (ethylene-propylene-diene copolymer) polymer as a main component and a rubber roller using the same, and more particularly to an improvement in friction coefficient and abrasion resistance. It is intended to achieve compatibility with the above.

[0002]

2. Description of the Related Art Rubber compositions used for OA equipment such as electrostatic copying machines, laser printers, and facsimile machines, and paper feed rollers for automatic teller machines require high abrasion resistance and a high coefficient of friction. Is done. This is because, when the roller surface is worn due to repeated use and the coefficient of friction is reduced, a slip occurs, and the paper conveyance force is reduced. Therefore, the applicant of the present application has proposed an EP having excellent mechanical strength.
EPDM polymer 10 is used without adding filler such as carbon black and silica to DM polymer.
Vulcanization is performed at 15 parts by weight or less with respect to 0 parts by weight,
A rubber roller made of a rubber composition having a rubber hardness as small as possible has been proposed (JP-A-8-63383). The EPDM polymer has excellent ozone resistance, and a copier or a laser printer using electrophotography generates ozone in the apparatus.

[0003] In recent years, OA equipment for personal use has increased, and various types of paper have been passed. Therefore, in order to obtain stable transportability even for such a variety of papers, the paper feed rubber roller includes:
Securing a higher coefficient of friction is required. For this reason,
In order to further increase the coefficient of friction, attempts have been made to mix rubber such as process oil into rubber to soften the rubber (reduce the rubber hardness), but as the amount of oil increases, the strength (mechanical strength) of the rubber increases. ) Is reduced, the abrasion resistance is reduced, and a problem occurs in that a stable paper conveying force cannot be maintained.

[0004]

Accordingly, the present inventors have attempted to lower the rubber hardness and increase the friction coefficient by blending butyl rubber with the rubber composition containing the EPDM polymer as a main component. However, in this case, since the dispersibility of the butyl rubber in the rubber composition is poor, the degree of vulcanization in the rubber composition varies, and the vulcanization (crosslinking) state in the composition is not uniform. Things. For this reason, even in a rubber roller manufactured by molding such a rubber composition, the abrasion resistance is still poor, and there has been a problem that paper feeding failure occurs due to long-term use.

The present invention has been made in view of the above circumstances, and is a rubber composition containing an EPDM polymer as a main component. The rubber composition has a low hardness, a high friction coefficient, and a low abrasion resistance. Provide excellent rubber composition,
It is an object of the present invention to provide a rubber roller capable of maintaining a stable paper conveying force for a long time.

[0006]

According to the present invention, there is provided a rubber composition comprising an EPDM polymer as a main component according to the present invention.
Parts by weight, at least 5 to 30 parts by weight of butyl rubber and 1 to 15 parts by weight of a polystyrene-based thermoplastic elastomer having a styrene content of 5 to 30%, and sulfur vulcanization. The present invention provides a rubber composition.

With the above structure, a polystyrene-based thermoplastic elastomer having an excellent affinity for butyl rubber can be used.
The dispersibility of the butyl rubber in the rubber composition is improved, and the degree of vulcanization throughout the rubber composition becomes uniform. As a result,
By adding butyl rubber, the rubber composition can be softened without lowering the mechanical strength of the rubber composition.

The reason why the amount of butyl rubber is set to 5 to 30 parts by weight based on 100 parts by weight of the EPDM polymer is that if the amount is less than 5 parts by weight, the rubber composition cannot be sufficiently softened.
When the amount exceeds 30 parts by weight, the vulcanization rate of butyl rubber is generally higher than that of EPDM polymer.
The incomplete vulcanization of the M polymer increases the permanent compression set of the rubber composition, decreases the mechanical strength, and makes it difficult to use as a rubber roller.

Further, the reason why a polystyrene-based thermoplastic elastomer having a styrene content of 5 to 30% is used is that when the styrene content is less than 5%, the affinity of the polystyrene-based thermoplastic elastomer for butyl rubber is low, and Cannot achieve the dispersion promoting effect of
If it exceeds 0%, the hardness of the polystyrene-based thermoplastic elastomer itself increases, and as a result, the hardness of the rubber composition increases, and the friction coefficient decreases.

In addition, the blending amount of the polystyrene-based thermoplastic elastomer per 100 parts by weight of the EPDM polymer is 1
When the amount is less than 1 part by weight, the effect of accelerating the dispersion of butyl rubber cannot be obtained, and when it exceeds 15 parts by weight, the polystyrene-based thermoplastic elastomer is a component that is not crosslinked in the composition. This is because the mechanical strength of the rubber composition decreases and the friction coefficient decreases.

Further, the present invention provides a rubber roller formed by molding the rubber composition according to claim 1 into a roller shape. In such a rubber roller, a high frictional force is obtained between the paper and the paper, and this can be maintained for a long period of time, so that stable paper transportability can be obtained for a long period of time.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as the EPDM polymer, those known per se can be used. Either one or both of an oil-extended EPDM polymer and a non-oil-extended EPDM polymer can be used. The diene component of the EPDM polymer is not particularly limited, and may be any of ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and the like.

The EPDM polymer (the polymer component excluding the oil component when the oil-extended EPDM polymer is contained) is blended in an amount of 30 to 90% by weight, preferably 36 to 87% by weight based on the whole rubber composition. This is because when the blending amount of the EPDM polymer is less than the specified amount, the original purpose of using the EPDM polymer, that is, the mechanical strength of the rubber composition is improved (wear resistance is improved) and the ozone resistance is improved. This is because the purpose of improving the quality is deviated.

As the butyl rubber, a halogenated butyl rubber in which a part of hydrogen is replaced by a halogen element such as chlorine can be used, in addition to a general butyl rubber made of a copolymer of isobutene and isoprene. The butyl rubber is used in an amount of 5 to 30 parts by weight based on 100 parts by weight of the EPDM polymer for the reason described above.

[0015] The polystyrene-based thermoplastic elastomer is
A known polystyrene-based thermoplastic having a triblock copolymer or a diblock copolymer composed of a hard polystyrene block and a soft olefin-based hydrocarbon and / or diolefin-based hydrocarbon elastomer block as a basic structure. Use an elastomer. In particular, those composed of a polystyrene block and an elastomer block containing no unsaturated bond are preferable in terms of heat resistance and weather resistance. As a specific example of such a preferable polystyrene-based thermoplastic elastomer, "Septon" (trade name) manufactured by Kuraray Co., Ltd. can be mentioned. In addition, the polystyrene-based thermoplastic elastomer, for the reasons described above,
A copolymer having a styrene content [(weight of styrene / weight of the entire copolymer) × 100] of 5 to 30 (weight)% in the copolymer is used. In particular, it is preferable to use one having a styrene content in the range of 13 to 30 (weight)%. Also,
The polystyrene-based thermoplastic elastomer is used in an amount of 1 to 1 based on 100 parts by weight of the EPDM polymer for the reason described above.
Use 5 parts by weight. In particular, it is preferable to use 5 to 10 parts by weight based on 100 parts by weight of the EPDM polymer.

For sulfur vulcanization, vulcanization additives such as a vulcanization accelerator, a vulcanization acceleration auxiliary, and a vulcanization retarder can be added together with a vulcanizing agent (sulfur). Examples of the vulcanization accelerator include Noxeller TET and TB manufactured by Ouchi Shinko Chemical Co., Ltd.
T and the like. Examples of the vulcanization accelerator include Noxeller Pz and Bz manufactured by Ouchi Shinko Chemical Co., Ltd. Examples of the vulcanization retarder include Noxeller Cz and Ns manufactured by Ouchi Shinko Chemical Co., Ltd.

In addition to the above-mentioned butyl rubber, polystyrene-based thermoplastic elastomer, and vulcanizing additives, fillers such as titanium oxide, silica, carbon black, clay, talc, and various oils for promoting softening. Other additives can also be added. When a filler is added, the amount of the filler is 1 to 100 parts by weight of the EPDM polymer.
Not more than 5% by weight.

The kneading of each of the above-mentioned components is preferred when a kneading machine such as a roll kneader is heated to about 80 to 120 ° C. because the kneading property of the rubber composition is improved. And
A rubber roller for paper feeding can be obtained by molding the rubber composition thus obtained into a desired roller shape by a conventional method.

Examples of the filler include titanium oxide, silica, carbon black, clay, and talc. Examples of the plasticizer include paraffin oil and naphthenic oil.

The above components are kneaded with a kneader known per se such as a roll kneader while heating to about 80 to 120 ° C. to produce a rubber composition. Then, the rubber composition is molded into a desired roller shape by a conventional method, vulcanized and molded to obtain a rubber roller of the present invention.

[0021]

The present invention will be described below based on examples and comparative examples. An example (Example 1) was prepared according to the formulation shown in Table 1 below.
To 6) and Comparative Examples (Comparative Examples 1 to 6) were manufactured, and each rubber composition was vulcanized and molded to produce a rubber roller.
The performance of the rubber roller was evaluated.

All rubber compositions were prepared by adding 5 parts by weight of zinc white, 1 part by weight of stearic acid,
7.5 parts by weight of a vulcanizing additive (containing sulfur)
This was carried out by kneading at 110 ° C. in a 5 L kneader.

After the rubber composition is extruded, the rubber roller is extruded using a mold corresponding to the shape of the rubber roller.
Vulcanized and molded at 70 ° C for 20 minutes, outer diameter 20m
m, a rubber roller having an inner diameter of 9 mm and a width of 10 mm were produced.

[0024]

[Table 1]

In the table, IIR indicates butyl rubber, TPE indicates a polystyrene-based thermoplastic elastomer, and St indicates styrene.

EPDM polymer is an oil-extended EP manufactured by Sumitomo Chemical.
DM polymer, Esplen 670F (trade name) was used. Butyl rubber is Butyl268 made by Japan Synthetic Rubber.
(Trade name) was used.

The polystyrene-based thermoplastic elastomer is
A copolymer of a polystyrene block and an olefin elastomer block containing no unsaturated bond and having a styrene content of 13% (Septon 204 manufactured by Kuraray Co., Ltd.)
3) Three types having a styrene content of 30% (Septon 4033 manufactured by Kuraray Co., Ltd.) and a type having a styrene content of 50% (Septon 1050 manufactured by Kuraray Co., Ltd.) were used.

The degree of vulcanization of the rubber composition is a total evaluation of the dispersibility and vulcanization state of the constituent materials in the rubber composition (rubber roller). The compression set (%) of the rubber composition (rubber roller) is evaluated. Was evaluated. The compression set (%) shows a smaller value as the dispersibility is better and the vulcanization is advanced.
0% or less was regarded as acceptable (○), and greater than 30% was rejected (×). The measuring method is as follows: after applying a specified compression strain at 70 ° C. and 25%, the sample was left for 22 hours, the residual strain was measured, and the compression set (%) = (residual strain / specified strain) × 10
0 was calculated. Note that the threshold value 30 is a value indicating the largest compression set among existing products having a market record.

The rubber hardness was measured based on a spring hardness test A type of JIS K6301. Based on the measured value of Comparative Example 1, the measured value of each Example and other Comparative Examples was represented by ±.

In the performance evaluation of the rubber roller, the amount of wear was measured at a temperature of 22.degree.
After passing 15,000 sheets of A4 size paper (PPC paper manufactured by Fuji Xerox Office Supply Co., Ltd.) for 7.5 hours in a 5% environment, the outer diameter of the rubber roller was measured, and the original diameter was measured. The amount of wear (mm) from the outer diameter was determined, and from the results, the expected amount of wear (mm) after 100,000 sheets were passed. In the evaluation, when the abrasion amount (mm) of Comparative Example 1 was set to 100, the abrasion amount (mm) of each Example and other comparative examples was converted into a relative value. The smaller the value, the better the test. A value larger than 100 was judged as failed (x), and a value less than 100 was judged as passed (o).

As shown in FIG. 1, the coefficient of friction between the rubber roller 1 and the plate 3 after the abrasion resistance test is as follows.
A load of A4 PPC paper connected to the load cell 5 is sandwiched, a load is applied to the rotating shaft 2 of the rubber roller 1, and the rubber roller 1 is pressed against the plate 3 as indicated by a black arrow in the drawing (load W = 25).
0 g). Next, under the conditions of a temperature of 22 ° C. and a humidity of 55%, the rubber roller 1 is rotated at a peripheral speed of 300 mm / sec in a direction indicated by a solid arrow a in the figure, and before and after paper passing, a direction indicated by a white arrow in the figure. Was measured by the load cell 5. And this measured value F (g)
And the load W (= 250 g) from the following equation
I asked. In the evaluation, when the friction coefficient of Comparative Example 1 was set to 100, the friction coefficients of the respective Examples and other Comparative Examples were converted into relative values. The larger the numerical value, the better the evaluation. The evaluation was evaluated as unacceptable (x) when it was 100 or less, and as acceptable (o) when it was greater than 100.

Μ = F (g) / W (g)

From the table, it can be seen that the butyl rubbers of Examples 1 to 6 (II
R) and a rubber roller made of a rubber composition produced by adding an appropriate amount of a polystyrene-based thermoplastic elastomer were prepared from the butyl rubber (IIR) of Comparative Example 1 and a standard rubber composition produced without adding a polystyrene-based thermoplastic elastomer. It can be seen that the rubber hardness is lower and the friction coefficient is higher than that of the rubber roller, and the abrasion resistance is improved.

The rubber composition prepared by adding only butyl rubber (IIR) without adding the polystyrene-based thermoplastic elastomer of Comparative Example 2 had a non-uniform vulcanization, a low degree of vulcanization, and a permanent compression set. It was unbearable for large use of. In Comparative Example 3, the addition amount of butyl rubber was too large, the vulcanization of the EPDM polymer as a main component was insufficient, the degree of vulcanization was low, and the rubber composition could not withstand use with a large compression set. In Comparative Example 4, the proportion of the styrene component in the polystyrene-based thermoplastic elastomer was too large, the polystyrene-based thermoplastic elastomer itself was hard, and the friction coefficient of the rubber roller was significantly reduced. Comparative Example 5
The polystyrene-based thermoplastic elastomer had too much compounding amount, and the polystyrene-based thermoplastic elastomer did not crosslink, so that the strength of the rubber composition was reduced and the abrasion resistance of the rubber roller was reduced.

[0035]

As described above, according to the rubber composition of the present invention, a rubber composition containing an EPDM polymer as a main component, wherein at least 5 to 30 parts by weight of butyl rubber is added to 100 parts by weight of the EPDM polymer. Parts and a 1 to 15 parts by weight of a polystyrene-based thermoplastic elastomer having a styrene content of 5 to 30%, and sulfur vulcanization. A rubber composition having high mechanical strength (abrasion resistance) can be obtained. Therefore, a rubber roller formed of such a rubber composition into a roller shape can obtain a high frictional force with paper for a long period of time, and exhibits stable paper transportability for a long period of time.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an apparatus for measuring a friction coefficient of a rubber roller.

[Explanation of symbols]

 1 Rubber roller

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Claims (2)

(57) [Claims] 1. A rubber composition containing an EPDM polymer as a main component, wherein at least 5 to 30 parts by weight of butyl rubber and 5 to 3 parts by weight of styrene are added to 100 parts by weight of the EPDM polymer.
0% polystyrene thermoplastic elastomer
A rubber composition comprising 15 parts by weight and sulfur vulcanization. 2. A rubber roller formed by molding the rubber composition according to claim 1 into a roller shape.