JP2000248133A - Rubber composition and rubber roller by use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition and a rubber roller by use thereof useful as a rubber material of the rubber roller for carrying which is excellent in abrasion resistance and unlikely to contaminate the surface of paper and film by blending electrically conductive carbon black as electrostatic measures. SOLUTION: This rubber composition contain carbon black wherein the rubber composition is an ethylene/propylene/diene rubber having an iodine value of not less than 20 as a base, an iodine-adsorption amount of 20 wt.% to 50 wt.% is not less than 40 mg/g and oil-absorbing amount of DBP(dibutyl phthalate) is not less than 100 ml/100 g; paraffin process oil or 5 wt.%-20 wt.%; and an organic peroxide as a crosslinking agent. In addition, the rubber roller has an elastic layer 2 of the rubber composed of a crosslinking form of such a rubber composition on the periphery of core axis 1 of the roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition which is useful as a transport roller and has improved contamination, and a rubber roller using the same.

[0002]

2. Description of the Related Art Heretofore, as a transport roller for transporting paper, film, and the like, a roller provided with a rubber layer having a moderate elasticity on a roller shaft has been widely used. For example,
In the medical field, as a roller for transporting medical films such as X-ray image capture films, and in the OA equipment field, paper or film transport rollers in electrophotographic copiers, laser beam printers, laser facsimile machines, etc. Further, in the field of photography, as a paper or film transport roller in a photo printing printer,
This rubber roller is used.

[0003] The characteristics required of such a roller include excellent abrasion resistance and the fact that paper or film does not wind around due to static electricity. In particular, the problem of static electricity is an important problem because it greatly affects the transportability. For this reason, conventionally, a large amount of carbon black has been blended into a rubber material to prevent charging.

[0004] However, as a result, the problem arises that the surface of the paper or film to be conveyed is contaminated with carbon black. Particularly, in the case of the medical films such as the above-mentioned X-ray image capturing film, the film is repeatedly used. Therefore, contamination by the carbon black is a major problem.

[0005]

As described above, conventionally, a rubber roller using a rubber material containing a large amount of carbon black has been used as a roller for transporting paper or film. There is a problem that the surface is contaminated. Particularly, a medical film or the like is used repeatedly, and this contamination is a serious problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has excellent abrasion resistance and has no risk of contaminating the surface of paper or film with carbon black blended as a measure against static electricity. It is an object to provide a rubber composition useful as a rubber material of a rubber roller for use and a rubber roller using the same.

[0007]

Means for Solving the Problems The rubber composition of the present invention comprises:
A rubber composition based on an ethylene propylene diene rubber having an iodine value of 20 or more, wherein the iodine adsorption amount of 25 to 50% by weight is 40 mg / g or more and DBP (phthalic acid) is used. (Dibutyl acid) It contains carbon black with an oil absorption of 100 ml / 100 g or more, and 5 to 20% by weight of paraffin-based process oil, and is characterized by being compounded with an organic peroxide as a crosslinking agent. I have.

In the rubber composition of the present invention, the ethylene propylene diene rubber has an iodine value of 20 to 40 and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 120 as described in claim 2.
The carbon black is preferably a carbon black
As described above, the iodine adsorption amount is 40 mg / g to 140 mg / g and the DBP (dibutyl phthalate) oil absorption amount is 100 ml / 100 g to 200 m
l / 100 g is preferred.

Further, in the rubber composition of the present invention, the organic peroxide may be 2,5-dimethyl
It is preferably at least one selected from -2,5-di- (t-butylperoxy) hexane, dicumyl peroxide and 1,3-bis (t-butylperoxyisopropyl) benzene.

The rubber roller according to the present invention is characterized in that the rubber roller has a rubber elastic layer formed of a crosslinked body of the rubber composition on the outer periphery of the roller core shaft.

Since the rubber composition of the present invention is based on an ethylene propylene diene rubber having an iodine value of 20 or more, it has excellent compression set characteristics. In addition, carbon black having an iodine adsorption amount of 40 mg / g or more and a DBP (dibutyl phthalate) oil absorption amount of 100 ml / 100 g or more is used.
% To 50% by weight and a paraffinic process oil in a range of 5% to 20% by weight, so that the carbon black is sufficiently dispersed and fully exerts its conductivity-imparting effect. Bleed of the process oil to the surface is prevented, and a decrease in wear resistance is also prevented. Furthermore, since an organic peroxide is blended as a crosslinking agent, bloom does not occur unlike sulfur, and high crosslinking is possible, so that compression set characteristics can be improved. Then, the respective effects of these respective components are added and multiplied, whereby the wear resistance is improved and the contamination is improved. Therefore, by using this, it is possible to provide a rubber roller which is excellent in abrasion resistance and transportability and which does not contaminate paper or film and is useful as a transport roller.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the rubber roller of the present invention.

In FIG. 1, reference numeral 1 denotes a roller core shaft made of a metal such as iron, and reference numeral 2 denotes a rubber elastic layer provided on the roller core shaft 1.

The rubber elastic layer 2 is a rubber composition based on ethylene propylene diene rubber (EPDM) having an iodine value of 20 or more, and having an iodine adsorption of 25 to 50% by weight of 40 mg / g or more. DBP (dibutyl phthalate) oil absorption
It is composed of a crosslinked body of a rubber composition containing 100 ml / 100 g or more of carbon black and 5% by weight to 20% by weight of a paraffinic process oil, and containing an organic peroxide as a crosslinking agent. I have.

As the ethylene propylene diene rubber,
In particular, the iodine value is 20-40 and the Mooney viscosity ML _{1 + 4} (100 ° C)
The use of 20 to 120 ethylene propylene diene rubber is preferred. If the iodine value is less than 20, not only the compression set properties will be insufficient, but also the contamination may not be sufficiently improved. Specifically, Mitsui Chemicals
EPT4070, Mitsui EPT9070E, Mitsui EPT4045, Mitsui EPT80
70E, Mitsui EPT4095, Mitsui EPT4021, JSREP35, JSREP37C and JSREP65 (all of which are trade names) manufactured by Nippon Synthetic Rubber Co., Ltd.

Further, as carbon black, in particular,
It is desirable to use one having an iodine adsorption amount of 40 mg / g to 140 mg / g and a DBP (dibutyl phthalate) oil absorption amount of 100 ml / 100 g to 200 ml / 100 g.

The amount of the carbon black was 25%.
When the amount is less than the weight percentage, the conductivity is reduced, and there is a possibility that the static electricity generated when the paper or the film is transported cannot be sufficiently prevented. Conversely, if it exceeds 50% by weight, the effect of the present invention cannot be sufficiently obtained, and there is a possibility that the paper or the film will be contaminated. When the amount of the paraffin-based process oil blended with such carbon black is less than 5% by weight, dispersion of the carbon black may be poor. Conversely, when the amount exceeds 20% by weight, the surface It may bleed and contaminate the paper or film, or reduce the abrasion resistance.

As the organic peroxide compounded as a crosslinking agent, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, dicumyl peroxide, 1,3-bis (t- Butylperoxyisopropyl) benzene, ethyl-3,3-bis (t-butylperoxy) butyrate, t-butylcumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-
Examples include trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, and (t-butylperoxyisopropyl) carbonate. Among them, low compression set can be obtained. 5-dimethyl-2,5-
Di- (t-butylperoxy) hexane, dicumyl peroxide and 1,3-bis (t-butylperoxyisopropyl) benzene are preferred. These may be used alone or as a mixture of two or more. In the present invention, the use of 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane is more preferred. This organic peroxide is usually added to 100 parts by weight of ethylene propylene diene rubber.
It is blended in an amount of 15 to 15 parts by weight.

In the present invention, a crosslinking aid such as N, N'-m-phenylenedimaleimide, toluaryl isocyanurate, zinc acrylate, zinc methacrylate, or a polyfunctional methacrylate monomer is used together with such an organic peroxide. It is desirable to add an agent. By adding such a crosslinking aid, the abrasion resistance and compression set characteristics can be further improved.

The rubber composition may optionally further contain a filler, a pigment, an antioxidant and other additives which are usually added to the ethylene propylene diene rubber. Other ethylene propylene diene rubbers, that is, ethylene propylene diene rubbers having an iodine value of less than 20 may be used in combination as long as they do not hinder the reaction.

The rubber roller is obtained by uniformly mixing the above-mentioned components using a kneader or the like to obtain a rubber compound, coating the rubber compound on the roller shaft 1 and heat-crosslinking it by a conventional method.

The rubber roller thus obtained is excellent in abrasion resistance, compression set characteristics, durability and the like.
No static electricity is generated when paper or film is transported, and paper or film is not contaminated.

Incidentally, in the present invention, the rubber elastic layer 2 may be provided on the roller core shaft 1 via another coating layer.

[0025]

Next, examples of the present invention will be described.

Example 1 Ethylene propylene diene rubber having an iodine value of 22 and a Mooney viscosity of ML _{1 + 4} (100 ° C.) 69 (trade name: Mitsui EPT, manufactured by Mitsui Chemicals, Inc.)
4070, described as EPDM A in the table) 100 parts by weight, and carbon black (Asahi Carbon Co., trade name Asahi # 60, described as carbon A in the table) with an iodine adsorption of 43 mg / g and a DBP oil absorption of 114 ml / 100 g And 30 parts by weight of paraffin-based process oil (PW-380 manufactured by Idemitsu Petrochemical Co.) and zinc oxide
5 parts by weight, stearic acid 1 part by weight, a cross-linking agent (2,5-dimethyl-2,5-di- (t-butylperoxy) hexane) 8 parts by weight, and a cross-linking aid (N, N ′) -m-phenylenedimaleimide) was uniformly mixed with 1 part by weight using a kneader to obtain a rubber composition.

Examples 2 and 3 A rubber composition was obtained in the same manner as in Example 1 except that the composition ratio of the components was changed as shown in Table 1.

With respect to the rubber compositions obtained in the above examples, tensile strength, elongation and hardness (JI
SA) and compression set (test conditions 70 ° C x 22 hours)
, Volume resistivity according to JIS K 6911, and abrasion resistance according to JIS K 6264-10 (Taber abrasion test). Table 1 shows the results. In addition,
These are all values measured by a test sample of the rubber composition obtained by crosslinking under the conditions of 170 ° C. for 30 minutes.

Further, in order to examine the contamination, the sample for compression set test was left on a polyethylene terephthalate film at a temperature of 80 ° C. for 24 hours, and the presence or absence of contamination on the film surface was visually observed (contamination test I). ). Furthermore, using a Taber abrasion tester, the sample (wear wheel) produced for the test was rotated 10,000 times on a polyethylene terephthalate film, and the film surface was visually inspected for contamination (contamination). Sex test II). The results of these tests are shown in Table 1 as ○ when contamination was not confirmed and as X when contamination was observed.

Comparative Examples 1 to 5 For comparison, an ethylene propylene diene rubber having an iodine value of 12, and a Mooney viscosity of ML _{1 + 4} (100 ° C.) 95 (trade name: Mitsui Chemicals, Inc., Mitsui Chemicals, Inc.)
Example using EPT3095 (denoted as EPDM B in the table) (Comparative Example 1), Example containing too little carbon black (Comparative Example 2), iodine adsorption amount 23 mg / g as carbon black, D
Example using carbon black with BP oil absorption of 63ml / 100g (trade name: Asahi Carbon Co., Ltd., trade name: Asahi # 50, described as carbon B in the table) (Comparative Example 3), Example using excess paraffinic process oil (Comparative Example) 4) As well as using sulfur as a crosslinking agent instead of organic peroxide, five kinds of crosslinking accelerators (dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl sulfenamide, tetraethylthiuram disulfide, dipentamethylene For the example (Comparative Example 5) in which thiuram tetrasulfide and di-n-butyldithiocarbamic acid were blended, the same property evaluation test as in the example was performed. The results are shown in Table 1 together with the composition.

[0031]

[Table 1] As is clear from Table 1, the rubber composition according to the present invention has sufficient mechanical properties, abrasion resistance, conductivity, and the like required for the rubber material for the rubber roller for transportation, and also has low contamination. On the other hand, in the case of the comparative example, any one of the characteristics is lacking, for example, the compression set characteristic of Comparative Example 1 is inferior, and the conductivity of Comparative Example 2 is insufficient, for example. .

[0032]

As described above, according to the present invention,
Based on the specific ethylene propylene diene rubber, and by specifying the carbon black and other composition components to be blended with it, a rubber composition sufficiently provided with various properties required for the rubber material used for the rubber roller for conveyance is obtained. By using this, it is possible to obtain a rubber roller which is excellent in transportability and durability and is useful as a transport roller which does not contaminate paper or film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a rubber roller of the present invention.

[Explanation of Signs] 1 ... Roller core shaft 2 ... Rubber elastic layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Yamazaki 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. 1-chome Showa Electric Wire & Cable Co., Ltd. F term (reference) 3F049 CA11 LB02 LB03 LB08 4J002 AE052 BB151 DA036 EK007 EK037 FD016 FD022 FD147 GF00

Claims (5)

[Claims] 1. A rubber composition based on an ethylene propylene diene rubber having an iodine value of 20 or more, wherein DBP (dibutyl phthalate) oil is absorbed at an iodine adsorption of 25 to 50% by weight of 40 mg / g or more. A rubber composition comprising carbon black in an amount of 100 ml / 100 g or more, and 5 to 20% by weight of a paraffin-based process oil, and containing an organic peroxide as a crosslinking agent. . 2. The ethylene propylene diene rubber,
Iodine value is 20-40 and Mooney viscosity ML _{1 + 4} (100 ℃) is 20-12
The rubber composition according to claim 1, wherein 0. 3. The carbon black according to claim 1, wherein the iodine adsorption amount is 40 mg / g to 140 mg / g and the DBP (dibutyl phthalate) oil absorption amount is 100 ml / 100 g to 200 ml / 100 g. The rubber composition as described in the above. 4. The method according to claim 1, wherein the organic peroxide is 2,5-dimethyl-2,5.
-A rubber composition comprising at least one selected from di- (t-butylperoxy) hexane, dicumyl peroxide and 1,3-bis (t-butylperoxyisopropyl) benzene. 5. A rubber roller having a rubber elastic layer comprising a crosslinked body of the rubber composition according to claim 1 on the outer periphery of the roller core shaft.