JP2727043B2 - Rubber composition for white belt - 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 for a white belt used as a material for forming a paper feed belt of a copying machine in an automatic document feeding section of a copying machine.

[0002]

2. Description of the Related Art FIG. 1 shows a copying machine capable of automatically copying a plurality of originals continuously. That is, in the copying machine 1, a plurality of originals 3 are placed on an original placing table 2 arranged at the upper end of one side of the main body in a stacked state with the front surface facing down. When the table cover 4 is rotated about the one end edge as shown by the arrow A in the drawing to fall on the platen glass 5 and then operated by pressing a switch (not shown), The provided paper feed belt 6 (endless elastic belt) made of white rubber travels in the direction of arrow B, and the document 3 placed on the document table 2 is moved.
Each time a copy is completed, the original is conveyed one by one from the upper side onto the original platen glass 5. In this case, in response to the copy, the copy paper 8 or 10 stored in the copy paper cassette 7 or 11 is conveyed into the copy machine 1 and
The characters and patterns on the surface of the original 3 are transferred and sent to the copy tray 9. As shown in FIG. 2, the paper feed belt 6 of the copying machine 1 travels by rotating two drive rollers 12 to convey the document 3. The paper feed belt 6 requires a frictional force to convey the document 3, and requires a document separation property for discharging the document 3. Further, the paper feed belt 6 must be white in order to convey the original 3 onto the original platen glass 5 and make a copy. As a material for forming the paper feed belt 6, conventionally, a terpolymer of ethylene-propylene-diene rubber (hereinafter abbreviated as “EPDM”) and epichlorohydrin-ethylene oxide-allyl glycidyl ether (hereinafter “ECO”) has been used. ) Is used as the main component. However, a paper feed belt made of a rubber composition containing EPDM and ECO as main components has a high electric resistance value, and the copy paper is charged and adsorbed to lower the document releasability. When the belt is washed with a solvent due to poor solvent properties, the belt stretches and slips during operation. In order to solve the above problem, the present inventors have conducted a series of studies and found that EPDM and acrylonitrile-butadiene rubber (hereinafter referred to as “NBR”) were used instead of the rubber composition containing EPDM and ECO as main components. It was found that the above problem can be solved by using a rubber composition containing (a) as a main component as a material for forming a belt.

[0003]

However, in the paper feed belt 6 formed by using the above rubber composition as a forming material, a problem arises in that, after vulcanization molding into a desired shape, yellow unevenness occurs on the belt. Occurs.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rubber composition for a white belt which does not cause yellow discoloration unevenness.

[0005]

In order to achieve the above object, a rubber composition for a white belt according to the present invention comprises ethylene-
Propylene rubber (hereinafter abbreviated as “EPM”) and EPD
M is a rubber composition for a white belt mainly containing NBR and at least one of M and a peroxide in an amount of 1.0 to 1.6 parts by weight based on 100 parts by weight of the rubber component. And at least one of the following components (A) to (C). (A) Multifunctional monomers. (B) sulfur or a vulcanization accelerator containing sulfur. (C) A phenolic antioxidant.

[0006]

In other words, the inventors of the present invention have repeatedly studied mainly on the cause of the yellowing in order to obtain a rubber composition for a white belt which does not turn yellow. Then, as a result of pursuing the cause, it was found that peroxide as a crosslinking agent blended in the rubber composition was involved in yellowing. When NBR is used, it is considered that -CN in the NBR may form a yellow compound during oxidative deterioration. From these research results, in order to prevent yellowing due to the peroxide,
First, it was found that yellowing can be prevented by setting the blending amount of the peroxide used as a crosslinking agent to a specific ratio. Recalling that the agent is allowed to react, it has been found that yellowing is prevented by containing at least one of the components (A) to (C) and reacting each of these components with the remaining crosslinking agent. The invention has been reached.

Next, the present invention will be described in detail.

[0008] The rubber composition for a white belt of the present invention comprises
It is obtained using at least one of PM and EPDM, NBR, a peroxide as a crosslinking agent, and the following components (A) to (C).

(A) Multifunctional monomers. (B) sulfur or a vulcanization accelerator containing sulfur. (C) A phenolic antioxidant.

[0010] The EPM and EPDM are not particularly limited, and those conventionally known can be used.

The NBR is not particularly limited, and a conventionally known NBR is used.

The mixing ratio of at least one of the above-mentioned EPM and EPDM (X) and NBR (Y) is X
It is preferable to set the ratio of / Y = 90/10 to 30/70. That is, when X exceeds 90 (Y is less than 10), the electric resistance increases, the original paper is charged and attracted to the belt, and a conveyance failure occurs, and conversely, X is less than 30 (Y exceeds 70). The reason for this is that although the electrical resistance is small and the transportability is good, the whiteness of the belt itself tends to deteriorate.

The peroxides include dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy)
3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne,
Organic peroxides such as n-butyl-4,4-bis (t-butylperoxy) valate and the like can be mentioned. It is necessary to set the amount of the peroxide to be 1.0 to 1.6 parts with respect to 100 parts by weight of the rubber component (hereinafter abbreviated as "part").
That is, if less than 1.0 part, sufficient vulcanization is not performed,
If the amount exceeds 1.6 parts, the amount of the peroxide is too large, the peroxide remains, and yellowing occurs.

Examples of the polyfunctional monomer as the component (A) include ethylene glycol dimethacrylate, triallyl isocyanate and the like. These polyfunctional monomers are used alone or in combination. The amount of the component (A) is preferably set to 1.0 to 1.6 parts with respect to 100 parts of the rubber component.

As the sulfur of the component (B), powdery sulfur used for vulcanization of ordinary rubber is used, and dipentamethylenethiuram tetrasulfide, 2-mercaptobenzothiazole is used as a vulcanization accelerator containing sulfur. And the like. And, when the compounding amount of the component (B) is sulfur,
It is preferable to set the amount to 0.1 to 0.3 part based on 100 parts of the rubber component, and in the case of a vulcanization accelerator containing sulfur,
It is preferable to set 1 to 3 parts for 100 parts of the rubber component.

As the phenolic antioxidant of the component (C), 2,2'-methylenebis (4-ethyl-6-
t-butylphenol), 2,5-di-t-butylhydroquinone, 2,2'-methylenebis (4-methyl-6
-T-butylphenol) and the like. And
The compounding amount of the component (C) is 0.1 part per 100 parts of the rubber component.
It is preferable to set 1 to 0.3 part.

[0017] In addition to the above components, other additives such as fillers, softeners, vulcanization accelerating aids, processing aids and the like are appropriately compounded in the rubber composition.

The rubber composition for a white belt of the present invention is obtained, for example, as follows. That is, the above EPM
And EPDM, at least one of NBR and peroxide at a predetermined ratio, and in addition to the above components, the above components (A) to (C) are further compounded and kneaded to form a white belt. A rubber composition is obtained.

Using the rubber composition for a white belt of the present invention, for example, the above composition is filled into a predetermined molding die and subjected to peroxide vulcanization molding to produce a desired white belt. be able to.

In the white belt thus obtained, the occurrence of yellowing during vulcanization molding is suppressed, and the white belt has a high degree of whiteness.

[0021]

As described above, the rubber composition for a white belt according to the present invention comprises at least one of EPM and EPDM, NBR as a main component, and the rubber component and a peroxide in a specific ratio. Further, at least one of the components (A) to (C) is blended. Therefore, the residual amount of the peroxide causing the yellowing phenomenon of the white belt is reduced during the belt formation as compared with the related art, so that the occurrence of uneven yellow after the vulcanization of the belt formation is suppressed. Further, the (A)
The component (C) reacts with the residual peroxide, whereby the residual amount of the peroxide can be further reduced, and more excellent yellowing resistance is realized. Moreover, the paper feed belt obtained by using this composition has excellent paper feedability. Therefore, when a white belt for a copying machine is produced using the rubber composition for a white belt of the present invention, a belt having a desired whiteness without yellow unevenness can be obtained as in the related art.

Next, examples will be described together with comparative examples.

[0023]

Examples 1 to 11 and Comparative Examples 1 to 5 The components shown in the following Tables 1 to 3 were blended in the proportions shown in the same table and kneaded to prepare rubber compositions for white belts.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

The thus obtained rubber compositions for white belts of Examples and Comparative Examples are filled in a molding die having a predetermined shape and vulcanized at 165 ° C. for 30 minutes. Produced a copying machine belt. And the breaking strength was measured using this belt. The results are shown in Table 4 below.
To Table 7. Further, the occurrence of yellow unevenness of the belt was visually confirmed, and the occurrence of yellow unevenness was evaluated. The evaluation results are shown in Tables 4 to 7 below. Further, the paper feeding property of the belt was evaluated by both the paper passing property and the solvent resistance according to the following method. The results are shown in Tables 4 to 7 below.

The breaking strength was measured according to JIS K6301.

The paper feedability in the paper feedability was evaluated by the following method. First, a paper feed belt of a copying machine made of the above rubber composition was incorporated into an automatic copying machine, and A4 paper, which is most frequently used for copying, was used for 10,000 copies.
When the failure occurrence rate of less than 0.1% (less than 10 sheets) due to charge adsorption or the like when the sheet is fed is ○, the failure occurrence rate is 0.1
% Or more (10 sheets or more) was evaluated as x. Further, the solvent resistance was evaluated by the following method.
That is, the paper feed belt of a copying machine made of the above rubber composition was incorporated into an automatic copying machine, wiped ten times with a cleaning solvent, and then fed five minutes later. The case where the belt slipped and the paper was not fed was evaluated as x.

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

From the results shown in Tables 4 to 7, the products of Comparative Examples 1 and 6 did not have uneven yellow color, but had low strength and could not be said to be very good for use as a belt. Also,
All of the other comparative examples had yellow unevenness. On the other hand, all of the examples had no yellow unevenness and had sufficient strength to be used as a copying machine belt. All of the examples had good paper feeding properties.

[Brief description of the drawings]

FIG. 1 is a perspective view of a copying machine.

FIG. 2 is a front view of a paper feed belt used in the copying machine.

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Claims (2)

(57) [Claims] A rubber composition for a white belt comprising at least one of ethylene-propylene rubber and ethylene-propylene-diene rubber and acrylonitrile-butadiene rubber as main components. A rubber composition for a white belt, comprising an oxide in an amount of 1.0 to 1.6 parts by weight, and containing at least one of the following components (A) to (C). (A) Multifunctional monomers. (B) sulfur or a vulcanization accelerator containing sulfur. (C) A phenolic antioxidant. 2. The polyfunctional monomer as the component (A) comprises:
The rubber composition for a white belt according to claim 1, wherein the rubber composition is ethylene glycol dimethacrylate or triallyl isocyanate.