JPH09316207A - Vulcanized rubber and rubber roller for transferring paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vulcanized rubber maintaining good wear resistance, high in initial friction coefficient, little in the lowering of the friction coefficient with time and resistant to ozone, and to provide a rubber roller used for transferring paper and comprising the vulcanized rubber. SOLUTION: This vulcanized rubber is obtained by vulcanizing a rubber composition containing an ethylene-propylene-diene copolymer rubber as a rubber component and a sulfenamide vulcanization accelerator as a vulcanization accelerator as essential components and further containing a filler in an amount of <=10wt.%. Therein, the sulfenamide vulcanization accelerator comprises at least one of the oxidative condensation product of a primary aliphatic amine with 2-mercaptothiazole and the oxidative condensation product of a secondary aliphatic amine with 2-mercaptobenzothiazole.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ethylene-propylene-diene rubber (hereinafter referred to as "ethylene-
"Propylene-diene rubber" may be abbreviated as "EPDM". ) As a main component and a sulfenamide vulcanization accelerator as a vulcanization accelerator as an essential component, and 1
The present invention relates to a vulcanized rubber obtained by vulcanizing a rubber composition that may contain 0% by weight or less of a filler, and a paper feeding rubber roller.

[0002]

2. Description of the Related Art An image forming apparatus such as a laser beam printer, an electrostatic copying machine (copier), and a plain paper facsimile machine always has a paper feeding mechanism. This paper feed mechanism is a combination of rubber rollers and the like.The material of the rubber roller for paper feed is generally a material with high friction that does not cause paper slip even after continuous use for a long period of time and durability that does not wear. It is required to be.

In a copying machine or the like, generation of ozone having a strong oxidizing power is unavoidable due to the image forming mechanism. for that reason,
The raw materials for the paper feed rubber roller used in the copier and the like are polynorbornene (northorex) and EPD.
Examples include ozone-resistant raw materials such as M, urethane rubber, and silicone rubber. One of these may be used alone or 2
A mixture of more than one species is used. Among them, EPDM, which is inexpensive, is often used recently. EPDM is used by converting it into vulcanized rubber to improve its physical properties.
Since there is no double bond in the main chain, it is difficult to vulcanize it by a usual method. Therefore, generally, a method of vulcanizing EPDM by using a vulcanization accelerator together is adopted.

Regarding the frictional force between a rotating body and an object in contact with it, generally, hysteresis friction, adhesive friction,
Friction such as scratching may be considered. Rubber rollers for paper feeding are much slower than tires traveling at a high speed on the road surface, and the load applied to the rollers is small. Therefore, it is considered that the rubber rollers are mainly due to adhesive friction. Therefore, in order to obtain a high frictional force in the paper feed rubber roller, it is preferable to make the roller as flexible as possible and to widen the paper contact area. Further, by making it soft, slipping between the roller and the paper can be prevented and abrasion resistance can be improved. For this reason, a plasticizer is usually added for the purpose of softening the roller. However, since the plasticizer bleeds onto the roller surface,
The friction coefficient of the roller surface may decrease significantly over time.

On the other hand, the vulcanized rubber used in the rubber roller for paper feeding contains a filler such as silica for the purpose of reinforcement and a plasticizer for improving the flexibility. When the blending amount of the filler is large, the hardness of the vulcanized rubber becomes high and the initial friction coefficient becomes small. Therefore, the blending amount must be 10% by weight or less.
However, if the blending amount is 10% by weight or less, the vulcanized rubber becomes soft and the initial friction coefficient becomes high, the slip between the roller made of vulcanized rubber and the paper is prevented, and the abrasion resistance is also improved. However, if the blending amount of the filler is reduced, the bleeding of the plasticizer cannot be prevented, so that the friction coefficient of the roller surface decreases with time.
Therefore, at present, a vulcanized rubber which has a high initial friction coefficient and whose time-dependent decrease in the friction coefficient is suppressed and a paper feed rubber roller made of this vulcanized rubber have not been realized.

[0006]

The problem to be solved by the present invention is to maintain good wear resistance, to have a high initial coefficient of friction, and to reduce the decrease of the coefficient of friction with time. It is intended to provide a vulcanized rubber and a paper feed rubber roller made of the vulcanized rubber.

[0007]

The vulcanized rubber of the present invention contains ethylene-propylene-diene rubber as a main component as a rubber component, and a sulfenamide vulcanization accelerator as an essential component as a vulcanization accelerator, and In a vulcanized rubber obtained by vulcanizing a rubber composition that may contain 10% by weight or less of a filler, the sulfenamide-based vulcanization accelerator comprises an aliphatic primary amine and 2-mercaptobenzothiazole. It is characterized by being at least one of an oxidative condensate and an oxidative condensate of an alicyclic secondary amine and 2-mercaptobenzothiazole.

It is preferable that the blending ratio of the ethylene-propylene-diene rubber is 60% by weight or more of the rubber component. The paper feeding rubber roller of the present invention is made of the above vulcanized rubber.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The vulcanized rubber of the present invention is obtained by vulcanizing a rubber composition having a specific composition.
This rubber composition will be described in detail below. Composition for rubber A rubber composition is a composition that contains a rubber component and a vulcanization accelerator and may contain 10% by weight or less of a filler. The rubber component contains ethylene-propylene-diene rubber (EPDM) as a main component, and the vulcanization accelerator contains a sulfenamide-based vulcanization accelerator as an essential component.

The rubber component is mainly composed of EPDM, and it is preferable that the compounding ratio thereof is 60% by weight or more based on the whole rubber component because the ozone resistance and the abrasion resistance are high. The rubber component may include a rubber component other than EPDM as necessary. Examples of such other rubber components include natural rubber, ethylene-propylene rubber (EPM),
Styrene-butadiene rubber (SBR), butyl rubber (I
IR), chlorosulfonated polyethylene, silicone rubber, urethane rubber, silicone-ethylene propylene mixed rubber and the like. Above all, it is preferable that the other rubber component is a natural rubber because good strength can be obtained. Further, the mixing ratio of the other rubber component in the rubber component is
When the content is 40% by weight or less of the whole rubber component, ozone resistance and abrasion resistance are high, so that it is preferable.

The vulcanization accelerator contains a sulfenamide vulcanization accelerator as an essential component. The sulfenamide vulcanization accelerator is at least an oxidative condensate of an aliphatic primary amine and 2-mercaptobenzothiazole and an oxidative condensate of an alicyclic secondary amine and 2-mercaptobenzothiazole. It is one kind. Examples of the aliphatic primary amines include n-butylamine, tert-butylamine, propylamine and the like. Among them, tert-butylamine is preferable because it is easily available and easy to handle as an industrial material.

Examples of the alicyclic secondary amine include dicyclohexylamine, pyrrolidine, piperidine and the like. Among them, dicyclohexylamine is preferable because it is easily available and easy to handle as an industrial material. The mixing ratio of the sulfenamide-based vulcanization accelerator in the rubber composition is not particularly limited, but, for example, 0.5 to 3 parts by weight with respect to 100 parts by weight of the rubber composition, an appropriate hardness is obtained. Is preferred, which is preferable. If the blending ratio of the sulfenamide-based vulcanization accelerator is less than 0.5 part by weight, the vulcanization rate will be slow. Further, when it exceeds 3 parts by weight,
Excessive sulfenamide vulcanization accelerator may be deposited on the roller surface and contaminate the paper.

As the sulfenamide vulcanization accelerator, those described above are indispensable, and in addition to this, an oxidation condensation product of an alicyclic primary amine and 2-mercaptobenzothiazole, and a morpholine compound and 2 It may contain an oxidative condensate with mercaptobenzothiazole. The sulfenamide-based vulcanization accelerator has different frictional forces when the rubber composition is vulcanized depending on its type, which is considered to be due to the difference in the cross-linking form depending on the vulcanization speed.

The vulcanization accelerator is tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide (TETD), tetrabutyl thiuram disulfide (TBTD), dipentamethylene thiuram tetrasulfide (DPTT). Other thiuram-based vulcanization accelerators such as zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC) and zinc di-n-butyldithiocarbamate (ZnBDC) It is preferable to further contain the vulcanization accelerator (1) in order to obtain appropriate hardness and wear resistance.

The mixing ratio of the other vulcanization accelerator in the rubber composition is not particularly limited, but, for example, the total amount of the other vulcanization accelerator is 2 to 8 with respect to 100 parts by weight of the rubber composition.
It is preferable if it is parts by weight, because an appropriate hardness can be obtained.
If the total amount of the other vulcanization accelerators is less than 2 parts by weight, an appropriate hardness roller cannot be obtained. On the other hand, if it exceeds 8 parts by weight, excess sulfenamide vulcanization accelerator may be deposited on the roller surface to contaminate the paper.

The rubber composition may contain 10% by weight or less of a filler in order to further improve the reinforcing property. Examples of the filler include powders such as silica, carbon black, clay, talc, calcium carbonate, dibasic phosphite (DLP), basic magnesium carbonate, and alumina. If the blending ratio exceeds 10% by weight, the hardness becomes too high and the initial friction coefficient becomes small, which is not preferable. Also, if a plasticizer described below is added to reduce the hardness, the plasticizer may bleed from the surface of the vulcanized rubber, causing a problem of contaminating the paper when used as a rubber roller for paper feeding. The compounding ratio of the agent is suppressed to 10% by weight or less.

In the rubber composition, for example, a paraffinic, naphthene-based, aromatic-based mineral oil-based softener, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl separate ( DO
S), plasticizers such as dioctyl adipate (DOA); vulcanization aids such as zinc oxide and stearic acid; sulfur; blowing agents;
Antioxidants; additives such as waxes can be added. The mixing ratio of these additives is not particularly limited, and a necessary amount can be appropriately used.

As a method for producing the rubber composition, a known method can be adopted. For example, each of the above-mentioned components is used at a temperature of 60 to 110 ° C. and 20 to 60 by using a rubber kneading device such as an open roll or a Banbury mixer. Obtained by kneading for minutes. Vulcanized rubber and rubber roller for paper feed The vulcanized rubber of the present invention is obtained by vulcanizing the rubber composition described above, and depending on the application etc., before vulcanization, if desired It may be molded into a shape.

As a method for producing a vulcanized rubber, a known method can be adopted. For example, the rubber composition is heated at 150 to 170 ° C. for 15 to 15 ° C. using an apparatus such as an electric press.
Obtained by vulcanizing for 60 minutes. Since the vulcanized rubber of the present invention contains ethylene-propylene-diene rubber as a main component as a rubber component, it is excellent in ozone resistance and is 10% by weight.
The vulcanized rubber becomes flexible and has a high initial coefficient of friction because it may contain the following fillers. Furthermore, since a specific sulfenamide-based vulcanization accelerator is contained as an essential component, the problem that the bleeding of the plasticizer cannot be prevented by reducing the blending amount of the filler is improved, and the initial friction coefficient is higher, and, It is possible to suppress a decrease in the friction coefficient with time. It is considered that the reason why the decrease in the friction coefficient with time is suppressed is because the cross-linking form formed during vulcanization is different from the conventional one, and the surface properties of the vulcanized rubber change.

As a method of manufacturing the rubber roller for paper feeding of the present invention, a known method can be adopted.
The rubber composition is prepared by a method such as injection molding, transfer molding, vulcanization can method, electric press method, or the like.
0 to 170 ° C., 10 to 120 minutes, pressure 3 to 70 kg /
Obtained by vulcanization at cm ² . The shape of the paper feeding rubber roller is not particularly limited as long as it is cylindrical or cylindrical.

FIG. 1 shows a schematic view in which a paper feeding rubber roller is used as a paper feeding roller of a copying machine. A shaft body 2 is fitted in the central cylindrical portion of the paper feed roller 1, and a pad 3 is provided so as to face the paper feed roller 1. When the shaft body 2 is rotated in the direction of the arrow, the paper feed roller 1 is also rotated, and the paper 4 near the paper feed roller 1 is rolled up, and this is passed through the gap between the paper feed roller 1 and the pad 3. As a result, the paper 4 is supplied to the inside of the copying machine.

Next, FIG. 2 shows a schematic diagram in which a paper feeding rubber roller is used as a conveying roller of a copying machine. As described above, two transport rollers 5 fitted with the shaft body 2 are prepared and arranged in opposition, and when each shaft body 2 is rotated in the opposite direction, the paper 4 in the vicinity of the transport roller 5 is caught, and this is transported. It comes to pass through the gap between the rollers 5. The rubber roller for paper feeding can be used in various devices having a mechanism for transporting paper. For example, the paper feeding rubber roller is a paper feed for image forming devices such as laser beam printers, electrostatic copying machines (copiers), and plain paper facsimile machines. When used for rollers, transport rollers, paper discharge rollers, etc., it maintains good wear resistance, has a high initial friction coefficient, shows little decrease in friction coefficient over time, and exhibits ozone-resistant physical properties. To be done.

[0023]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples. (Example 1) The composition shown in Table 1 was used and kneading was performed for 40 minutes at 70 ° C using an open roll to obtain a rubber composition (1).

The obtained rubber composition (1) is molded by using a transfer molding device, put into a mold, and pressure 50 is applied.
kg / cm ² , temperature of 160 ° C., time of 30 minutes,
A paper feed rubber roller (1) made of vulcanized rubber was produced by electric pressing. The rubber roller (1) has an outer diameter of 20.
mm, inner diameter 9 mm, width 10 mm. A paper passing test was conducted on the obtained paper feeding rubber roller (1), and its performance was evaluated by the following evaluation methods. The results are shown in Table 2. [Evaluation Method] Hardness The hardness was measured according to JIS A. Ozone resistance The surface condition was observed by leaving it in an atmosphere having an ozone concentration of 100 pphm for 12 hours, and judged according to the following evaluation criteria. ◯: Good Δ: Fairly good ×: Poor friction coefficient A load of 250 g was applied to 7.5 sheets of A4 size paper (P paper manufactured by Fuji Xerox Office Supply Co., Ltd.).
I passed it in time. The force applied to the paper was measured with a load cell under conditions of a load of 250 g and a roller speed of 255 mm / s for every 5000 sheets, and this was divided by the load to obtain a friction coefficient.

The difference Δμ between the friction coefficient (b) after passing 15,000 sheets and the initial friction coefficient (a) was calculated. The smaller Δμ, the smaller the decrease in the friction coefficient due to the passing of paper. The difference between the outer diameter of 20 mm before passing the abrasion resistant paper and the outer diameter after passing 15,000 sheets was calculated. The smaller the difference, the smaller the decrease in wear resistance over time, indicating that the wear resistance is maintained well. (Examples 2 to 5, Reference Examples, Comparative Examples 1 and 2) In the same manner as in Example 1, a rubber composition was obtained and then subjected to electric pressing to produce rubber rollers for paper feed made of vulcanized rubber. Each rubber roller has an outer diameter of 20 mm, an inner diameter of 9 mm, and a width of 10 mm.
mm.

Each of the obtained rubber rollers for paper feeding was subjected to a paper passing test in the same manner as in Example 1, and its performance was evaluated by the following evaluation methods. The results are shown in Table 2.

[0027]

[Table 1]

* 1 Sumitomo Chemical Co., Ltd. E600F EP
DM: extender oil = 50: 50 (weight ratio). * 2 Nipsil VN3 made by Nippon Silica, and the values in parentheses are the compounding ratios in the rubber composition expressed as% by weight. * 3 Noxceller TET, a thiuram-based vulcanization accelerator manufactured by Ouchi Shinko Chemical.

* 4 Nox Cellar BZ manufactured by Ouchi Shinko Chemical Co., Ltd.
Dithiocarbamic acid vulcanization accelerator. * 5 Nocceller CZ, manufactured by Ouchi Shinko Chemical Co., Ltd. A sulfenamide vulcanization accelerator composed of an oxidative condensation product of an alicyclic primary amine and 2-mercaptobenzothiazole. * 6 Nocceller DZ manufactured by Ouchi Shinko Kagaku Co., Ltd. A sulfenamide vulcanization accelerator composed of an oxidative condensation product of an alicyclic secondary amine and 2-mercaptobenzothiazole.

* 7 Nocceller NS manufactured by Ouchi Shinko Chemical Co., Ltd.
A sulfenamide-based vulcanization accelerator comprising an oxidative condensation product of an aliphatic primary amine and 2-mercaptobenzothiazole.

[0031]

[Table 2]

Since the rubber roller for paper feeding of the reference example has a high blending ratio of silica, Δμ is small, but a rubber composition containing neither vulcanization accelerator DZ nor vulcanization accelerator NS which is a specific vulcanization accelerator. It has a low initial coefficient of friction and is inferior in wear resistance. The rubber rollers for paper feed of Examples 2 and 5 and Comparative Example 1 both contained the same amount of silica, but Example 2 was obtained from a rubber composition containing the vulcanization accelerator DZ, and Example 5 is obtained from a rubber composition containing the vulcanization accelerator NS, whereas Comparative Example 1 is obtained from a rubber composition containing no vulcanization accelerator. In Examples 2 and 5, Δμ is considerably smaller than in Comparative Example 1, bleeding of the plasticizer is prevented, and hardness and initial friction coefficient are also high.

The rubber rollers for feeding paper of Examples 1 to 3 and Comparative Example 2 were all obtained from the rubber composition containing the same amount of the vulcanization accelerator DZ, but in Examples 1 to 3, silica rollers were used. The compounding ratios are 0% by weight, 4.5% by weight, and 8.7% by weight, and all are 10% by weight or less, whereas in Comparative Example 2, it is 12.4% by weight. If the blending ratio of silica increases, the wear resistance decreases. Mixing ratio of silica is 10
When it exceeds the weight%, the initial friction coefficient becomes low.

The rubber roller for paper feeding of Example 4 was obtained from a rubber composition containing 40% by weight of natural rubber in addition to EPDM as a rubber component, but has good ozone resistance and initial friction. The coefficient is high and Δμ is small.

[0035]

The vulcanized rubber of the present invention contains ethylene-propylene-diene rubber as a main component as a rubber component, a sulfenamide vulcanization accelerator as a vulcanization accelerator as an essential component, and 10% by weight or less. In a vulcanized rubber obtained by vulcanizing a rubber composition which may contain a filler, the sulfenamide-based vulcanization accelerator comprises an aliphatic primary amine or an alicyclic secondary amine and 2-mercapto. Since it is characterized by being at least one kind of oxidative condensate with benzothiazole, while maintaining good wear resistance, the initial friction coefficient is high and the decrease in friction coefficient with time is small. Ozone vulcanized rubber can be provided.

Since the rubber roller for paper feeding of the present invention is made of this vulcanized rubber, it has the above-mentioned physical properties.

[Brief description of drawings]

FIG. 1 is a schematic diagram in which a paper feeding rubber roller of the present invention is used as a paper feeding roller of a copying machine.

FIG. 2 is a schematic diagram in which the paper feeding rubber roller of the present invention is used as a conveyance roller of a copying machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper feed roller 2 Shaft 3 Pad 4 Paper 5 Transport roller

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Claims (3)

[Claims] 1. A rubber component containing ethylene-propylene-diene rubber as a main component, and a vulcanization accelerator containing a sulfenamide-based vulcanization accelerator as an essential component.
In a vulcanized rubber obtained by vulcanizing a rubber composition that may contain a filler by weight or less, the sulfenamide-based vulcanization accelerator oxidizes an aliphatic primary amine and 2-mercaptobenzothiazole. A vulcanized rubber which is at least one of a condensate and an oxidative condensate of an alicyclic secondary amine and 2-mercaptobenzothiazole. 2. The vulcanized rubber according to claim 1, wherein the blending ratio of the ethylene-propylene-diene rubber is 60% by weight or more of the rubber component. 3. A paper feed rubber roller comprising the vulcanized rubber according to claim 1.