JPH1017162A - Vulcanized rubber and paper feeding-carrying rubber roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanized rubber which is excellent in ozone resistance and has high durability and is excellent in molding workability, and a paper feeding-carrying rubber roller composed of the vulcanized rubber, by containing ethylene-propylene-diene rubber and vulcanizing a rubber composition. SOLUTION: A first rubber composition contains ethylene-propylene-diene rubber as a rubber component. In the first rubber composition, Mooney scorch time is not less than 15 minutes at 130 deg.C, and vulcanizing speed is not more than 9 minutes at 170 deg.C, and Mooney viscosity is not more than 30 at 130 deg.C. A shaft body 2 is fitted in a central hole part of a paper feeding roller 1 composed of vulcanized rubber, and a pad 3 is arranged so as to be opposed to the paper feeding roller 1. When the shaft body 2 is rotated in the arrow direction around a central shaft, the paper feeding roller 1 also rotates in the same direction as the same central shaft as the center, and rolls in paper 4 existing in the vicinity of the paper feeding roller 1. This comes to pass through a clearance between the paper feeding roller 1 and the pad 3, and the paper 4 is supplied to the inside of a copying machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanized rubber and a paper feed / transport rubber roller.

[0002]

2. Description of the Related Art Image forming apparatuses such as printers, copiers and facsimile machines have a paper feed mechanism in which various rollers and the like are combined. In a copy machine, etc., due to the image forming mechanism,
Ozone having a strong oxidizing power is generated in the photosensitive drum portion. Therefore, as a material of the roller, generally,
A vulcanized rubber using an ozone-resistant raw material such as polynorbornene (Nosorex), ethylene-propylene-diene rubber (EPDM), urethane rubber, and silicone rubber is used. Among them, recently, EPDM is often used as a raw material for rollers because of its low cost.

[0003]

Among the above rollers, the rubber roller for feeding and conveying paper used for feeding paper to the apparatus and for moving the paper inside the apparatus is not only resistant to ozone but also used for a long time. However, it is required that the material has a high conveying force capable of reliably transferring paper and has excellent durability. E
PDM is used after being converted into vulcanized rubber in order to improve physical properties. However, since the main chain has no double bond, natural rubber,
General vulcanization accelerators such as thiuram-based, thiazole-based, and sulfenamide-based rubbers used for styrene-butadiene copolymer rubber cannot be sufficiently vulcanized, and do not result in vulcanized rubber having a sufficiently high friction coefficient. . Therefore, it is usual to produce a vulcanized rubber by sufficiently vulcanizing a combination of various vulcanization accelerators including a vulcanization accelerator having a strong accelerating effect.
However, when various vulcanization accelerators are combined, it is technically difficult to control the vulcanization reaction. That is,
Mooney scorch time is short, and it is difficult to control the vulcanization rate.
Inability to mass-produce rubber rollers for paper feed / conveyance, and even if mass production is possible, the vulcanization rate is extremely high, making it impossible to use an injection molding method, which is a simple method, and increasing production costs. There is a problem.

[0004] The problem to be solved by the present invention is to provide a vulcanized rubber having excellent ozone resistance, high durability even after long-term use, and excellent moldability, and a paper feed / roll made of this vulcanized rubber. It is to provide a rubber roller for conveyance.

[0005]

Means for Solving the Problems The present inventors have proposed EPD.
As a result of intensive studies on the types of vulcanization accelerators used for vulcanizing the rubber composition containing M, thiuram-based, thiazole-based, and sulfen-based compounds, which are not generally high enough to accelerate vulcanization, are used. By using an amide-based vulcanization accelerator in combination with a vulcanization accelerator having a higher vulcanization promoting strength than these, it is possible to obtain good moldability and long-term durability. I found it. Further, the present inventors have found that moldability and durability are related to specific physical properties of the rubber composition, and have reached the present invention.

The first vulcanized rubber of the present invention contains ethylene-propylene-diene rubber as a rubber component and has the following (1)
It is a vulcanized rubber obtained by vulcanizing a rubber composition having the characteristics shown in (3) (hereinafter sometimes referred to as a first rubber composition). (1) Mooney scorch time 15 at 130 ° C
(2) A vulcanization rate of 9 minutes or less at 170 ° C. (3) A Mooney viscosity of 30 or less at 130 ° C. The second vulcanized rubber of the present invention comprises a rubber component containing an ethylene-propylene-diene rubber, and thiuram. , A thiazole-based and a sulfenamide-based vulcanization accelerator, a vulcanization accelerator containing a zinc salt of dithiocarbamate, and a metal salt of dithiocarbamate other than the zinc salt, and a sulfonamide-based scorch prevention Vulcanized rubber obtained by vulcanizing a rubber composition (hereinafter sometimes referred to as a second rubber composition) which may further contain a filler of 40% by weight or less of the rubber component. .

[0007] A rubber roller for feeding and transporting the present invention is made of the above vulcanized rubber.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The first vulcanized rubber of the present invention is obtained by vulcanizing a first rubber composition having specific physical properties. The second vulcanized rubber of the present invention is obtained by vulcanizing a second rubber composition having a specific composition. First, these rubber compositions will be described in detail below. First rubber composition The first rubber composition contains ethylene-propylene-diene rubber (EPDM) as a rubber component. The blending ratio of EPDM in the rubber component is not particularly limited, but the blending ratio described below is preferable because ozone resistance and abrasion resistance increase.

The first rubber composition further comprises the following (1)
It has the properties of (3) to (3). (1) Mooney measured according to JIS K-6300
ー Scorch time (t _Ten) Is at 130 ° C for 15 minutes
That is all. Mooney scorch time is 20-30 minutes
When there is, it is preferable because moldability is improved. Mooney
The scorch time is less than 15 minutes at 130 ° C.
For example, when molding a rubber composition during injection molding,
May cause rubber scorch, and moldability is sufficient
is not.

(2) The vulcanization rate (T90) measured according to ASTM D-2084 is 9 minutes or less at 170 ° C. A vulcanization rate of 6 to 9 minutes is preferable because vulcanization can be performed in a short time and productivity is excellent. When the vulcanization rate time exceeds 9 minutes at 170 ° C., the vulcanization time is long, so that it is not suitable for mass production and the moldability is not sufficient.

(3) The Mooney viscosity (ML _{1 + 4} ) measured according to JIS K-6300 is 30 or less at 130 ° C. When the Mooney viscosity is 15 to 25,
In particular, injection molding is easy, and molding processability is excellent, so that it is preferable. If the Mooney viscosity exceeds 30 at 130 ° C., early vulcanization proceeds and molding processability is not sufficient.

The method for producing the first rubber composition is not particularly limited, and a known method can be employed. As a method for producing the first rubber composition, for example, a method for producing a second rubber composition described later can be mentioned.
The first rubber composition contains EPDM as a rubber component,
If it has the physical properties of the above (1) to (3), E
Any component other than the PDM may be included, and the mixing ratio of the component is not particularly limited.
The following second rubber compositions can be mentioned as preferable ones. Second rubber composition The second rubber composition contains ethylene-propylene-diene rubber (EPDM) as a rubber component. The mixing ratio of EPDM in the rubber component is not particularly limited, but is preferably 30% by weight or more of the whole rubber component because ozone resistance and abrasion resistance are increased.

The rubber component may contain a rubber component other than EPDM as required. As such other rubber components, for example, natural rubber, ethylene-propylene rubber (EPM), styrene-butadiene rubber (SB)
R), butyl rubber (IIR), chlorosulfonated polyethylene, silicone rubber, urethane rubber, silicone
Ethylene propylene mixed rubber can be exemplified.
Above all, it is preferable that the other rubber component is a natural rubber because good strength can be obtained. Further, it is preferable that the compounding ratio of the other rubber component in the rubber component is 70% by weight or less based on the whole rubber component because ozone resistance and abrasion resistance are high.

[0014] The second rubber composition comprises at least one general-purpose vulcanization accelerator selected from thiuram-based, thiazole-based and sulfenamide-based vulcanization accelerators, zinc dithiocarbamate, and a salt other than the zinc salt. (Hereinafter, metal salts of dithiocarbamic acid other than zinc salts may be referred to as “dithiocarbamic acid or other metal salts”).

As the thiuram vulcanization accelerator, for example, tetramethylthiuram monosulfide (TMT)
M), tetramethylthiuram disulfide (TMT)
D), tetraethylthiuram disulfide (TET)
D), tetrabutylthiuram disulfide (TBT)
D), dipentamethylenethiuram tetrasulfide (D
PTT) and the like.

Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole zinc salt (ZnMBT), and 2-mercaptobenzothiazole sodium salt (MBT). NaMBT), 2
-Cyclohexylamine salt of mercaptobenzothiazole (CMBT), 2- (2'4-denitrophenylthio) benzothiazole (DPBT) and the like.

The sulfenamide vulcanization accelerators include
For example, N-cyclohexyl-2-benzothiazolesulfenamide (CBS), Nt-butyl-2-benzothiazolesulfenamide (BBS), N-oxyethylene-2-benzothiazolesulfenamide (OBS), N, N'-diisopropyl-2-benzothiazolesulfenamide (DPBS), N, N'-dicyclohexyl-2-benzothiazolesulfenamide and the like can be mentioned.

The general-purpose vulcanization accelerator is not particularly limited as long as it is at least one selected from the thiuram-based, thiazole-based, and sulfenamide-based vulcanization accelerators.
The vulcanization accelerator contains, in addition to the general-purpose vulcanization accelerator, zinc dithiocarbamate and dithiocarbamic acid and other metal salts. Examples of the zinc dithiocarbamate include zinc dimethyldithiocarbamate (ZnMDC),
Zinc diethyldithiocarbamate (ZnEDC), di-
zinc n-butyldithiocarbamate (ZnBDC), zinc pentamethylenedithiocarbamate (ZnPDC),
Zinc ethylphenyldithiocarbamate (ZnEPD)
C) and the like. The zinc dithiocarbamate may be any one of these, or two or more thereof.

Examples of dithiocarbamic acid and other metal salts include tellurium, selenium, lead, cadmium, copper,
Dimethyldithiocarbamate, diethyldithiocarbamate, di-n of metals such as bismuth, iron and nickel
-Butyldithiocarbamate, pentamethylenedithiocarbamate, ethylphenyldithiocarbamate and the like. Dithiocarbamic acid and other metal salts may be any one of these,
There may be more than one species.

The mixing ratio of the general-purpose vulcanization accelerator, zinc dithiocarbamate and dithiocarbamic acid and other metal salts in the vulcanization accelerator is not particularly limited. It is preferable to use 60 to 90% by weight of the agent, 5 to 30% by weight of zinc dithiocarbamate, and 5 to 30% by weight of dithiocarbamic acid and other metal salts because Mooney scorch time and vulcanization rate become appropriate.

The mixing ratio of the vulcanization accelerator in the second rubber composition is not particularly limited. For example, if the amount is 1.5 to 5% by weight of the rubber component, the durability after vulcanization is reduced. It is preferable because excellent physical properties can be obtained. The second rubber composition contains a sulfonamide-based scorch inhibitor. Sulfonamide-based scorch inhibitors are effective at both low and high temperatures, do not hinder vulcanization, and basically do not significantly affect vulcanization properties. The sulfonamide scorch inhibitor is not particularly limited.

The proportion of the sulfonamide-based scorch inhibitor in the second rubber composition is not particularly limited. For example, if the amount is 0.1 to 0.5% by weight of the rubber component, the scorch property is reduced. Is preferred because it is stable and does not bloom. The second rubber composition may contain a filler having a compounding ratio of 40% by weight or less of the rubber component in order to 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. Further, it is preferable that the compounding ratio of the filler in the second rubber composition is 5 to 15% by weight of the rubber component because the frictional force becomes high and the durability becomes excellent. If the compounding ratio of the filler exceeds 40% by weight, the hardness becomes too high and the frictional force decreases.

If necessary, the rubber composition may contain, for example, a mineral oil softener such as a paraffinic, naphthenic or aromatic mineral, dioctyl phthalate (DOP), dibutyl phthalate (DBP), or dioctyl sepate ( DO
Plasticizers such as S) and dioctyl adipate (DOA); vulcanization aids such as zinc oxide and stearic acid; sulfur;
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 the method for producing the second rubber composition, a known method can be adopted. For example, the above-mentioned components are mixed at 60 to 130 ° C. using a rubber kneading apparatus such as an open roll or a Banbury mixer. It is obtained by kneading for 10 to 60 minutes. Vulcanized Rubber and Rubber Roller for Feeding and Conveying The first and second vulcanized rubbers of the present invention (hereinafter sometimes simply referred to as vulcanized rubber) are obtained by vulcanizing the rubber composition described above. Depending on its use, it may be formed into a desired shape before vulcanization, if necessary, or may be formed into a desired shape while vulcanizing.

As a method for producing the vulcanized rubber, a known method can be adopted.
Using devices such as injection molding machines and press molding machines, 140-
It is obtained by vulcanizing at 180 ° C. for 10 to 120 minutes. The paper feed / transport rubber roller of the present invention is made of vulcanized rubber. A known method can be employed as a method for manufacturing the paper feed / conveyance rubber roller. For example, a method of manufacturing the rubber roller for feed / conveyance using an injection molding machine while vulcanizing the rubber roller. Alternatively, the rubber composition is subjected to transfer molding, injection molding, vulcanization can method, electric press method or the like at 150 to 170 ° C. and 10 to 12
There is a method of molding and vulcanizing at a pressure of 3 to 60 kg / cm ² for 0 minute.

The shape of the rubber roller for feeding / transporting is not particularly limited as long as it is cylindrical or cylindrical. FIG. 1 is a schematic diagram showing a paper feed / transport rubber roller used as a paper feed roller of a copying machine. A shaft 2 is fitted in the center hole of the paper feed roller 1, and a pad 3 is provided so as to face the paper feed roller 1.
Is provided. When the shaft body 2 is rotated around the central axis in the direction of the arrow, the paper feed roller 1 also rotates in the same direction about the same central axis as the center of rotation, and the paper 4 near the paper feed roller 1 is entrained. The paper 4 passes through the gap between the paper roller 1 and the pad 3, and the paper 4 is supplied to the inside of the copying machine.

Next, FIG. 2 is a schematic diagram in which a rubber roller for feeding and conveying is used as a conveying roller of a copying machine. In the same manner as described above, two transport rollers 5 with the shafts 2 mounted thereon are prepared and opposed to each other. When the respective shafts 2 are rotated in opposite directions, the paper 4 near the transport rollers 5 is entangled. The paper passes through the gap between the opposing transport rollers 5 and 5.

The paper feed / transport rubber roller can be easily mass-produced due to its excellent molding workability, and can be used in various apparatuses having a mechanism for transporting paper. For example, if it is used for a paper feeding roller, a conveying roller and a paper discharging roller of an image forming apparatus such as a laser beam printer, an electrostatic copying machine (copying machine), and a plain paper facsimile machine, the durability will be maintained even after long use. The properties of high and ozone resistance are sufficiently exhibited.

[0029]

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) With the composition shown in Table 1, the mixture was kneaded at 70 ° C for 40 minutes using an open roll, and allowed to stand in an atmosphere of 55% humidity for 20 days to obtain a rubber composition (1).

The obtained rubber composition (1) was molded using an injection molding machine (S-78R-750 manufactured by Wako Seiki Co., Ltd.) at a screw temperature of 80 ° C. and a mold temperature of 170 ° C. for 15 minutes. Then, a rubber roller (1) was manufactured. The molding processability, conveyance force durability and ozone resistance of the obtained rubber roller (1) were evaluated by the following evaluation methods, and the results are shown in Table 2. The case where [Evaluation method] moldability rubber roller is nicely molded with ○ (moldability good), may not be molded burnt rubber in the middle molding, if warpage in the rubber roller is insufficient as a product occurs (Poor molding processability). Conveying force durable rubber roller with a laser beam printer (manufactured by Hewlett Packard, Laser Jet4 Plus) of the integrate into an A4 size paper (manufactured by Fuji Xerox Co., Ltd., P-A
4) was passed for 7 days (total of 2,000 sheets), and the conveying force before and after the sheet passing was measured by the method shown in FIG.

Conveyance reduction rate (%) = 100 (F ₀ −F
₂₀₀₀ ) / 20F ₂₀₀₀ F ₀ : Initial transport force (g) F ₂₀₀₀ : Transport force after paper passing (g) When the rate of decrease in transport force is 1.5% or less, ○ (good transport force durability) and transport × when the power reduction rate exceeds 1.5%
(Poor conveyance durability). A 10 cm × 10 cm rubber plate is formed by molding an ozone-resistant rubber composition, and this is punched into a dumbbell No. 1 shape according to JIS K-6301 and stretched by 10% in a test machine maintained at an ozone concentration of 50 pphm and 40 ° C. It was left to stand in a state where it was left, and it was examined whether a crack was generated on the surface of the rubber. The case where no crack was generated on the surface of the rubber was evaluated as ○ (good ozone resistance), and the case where a crack was generated on the surface of rubber was evaluated as x (poor ozone resistance).

Further, the following rubber composition (1) was used.
Mooney scorch time (t _Ten), Vulcanization rate (T
90) and Mooney viscosity (ML_{1 + 4}) Measure that
The results are shown in Table 3.Mooney scorch time (t ₁₀ ) It measured at 130 degreeC according to JISK-6300.Vulcanization rate (T90) Measured at 170 ° C. according to ASTM D-2084.Mooney viscosity (ML _{1 + 4} ) It measured at 130 degreeC according to JISK-6300. (Examples 2 to 5, Comparative Examples 1 to 7)
With the formulations shown in Tables 1 and 2, respectively,
Using a roll, knead at 70 ° C for 40 minutes, humidity 55%
Rubber composition (2) ~
(5) and comparative rubber compositions (1) to (7) were obtained.

The obtained rubber composition was molded in the same manner as in Example 1 to produce rubber rollers (2) to (5) and comparative rubber rollers (1) to (7). With respect to the obtained rubber roller, its molding processability, conveyance force durability and ozone resistance were evaluated by the following evaluation methods, and the results were shown in Tables 3 and 4.
It was shown to.

[0034]

[Table 1]

[0035]

[Table 2]

* 1 ESPRIN 60 manufactured by Sumitomo Chemical Co., Ltd.
0F EPDM: extending oil = 50: 50 (weight ratio). * 2 N232S made by Japan Synthetic Rubber. * 3 Nipsil VN-3 manufactured by Nippon Silica. * 4 Shiraishi calcium white luster flower CC.

* 5 Mitsubishi Chemical Diamond Black H. * 6 Nouchira TET manufactured by Ouchi Shinko Chemical. * 7 Nouchira DM manufactured by Ouchi Shinko Chemical. * 8 Noxeller BZ manufactured by Ouchi Shinko Chemical. * 9 Ouchi Shinko Chemical Noxeller EZ.

* 10 Noxeller P manufactured by Ouchi Shinko Chemical
X. * 11 Noxeller TTTE manufactured by Ouchi Shinko Chemical. * 12 Ouchi Shinko Chemical Noxeller TTCU. * 13 Vulkalent E / C manufactured by Bayer. * 14 PVI manufactured by Monsanto Japan.

* 15 Zinc flower No. 1 manufactured by Hakusui Chemical. * 16 Stearic acid manufactured by NOF Corporation. * 17 Tsurumi Chemical powdered sulfur.

[0040]

[Table 3]

[0041]

[Table 4]

* A Burning occurred. * B Vulcanization took time. * C The vulcanized rubber was damaged when removed from the mold, and vulcanization was insufficient. * D Viscosity was high, injection was not successful, and molding was difficult. In Examples 1 to 5, all are excellent in molding workability, conveyance force durability and ozone resistance. Comparative Examples 2, 3 and 6
However, one of the essential vulcanization accelerators is lacking, and the vulcanization rate is low or vulcanization is insufficient, resulting in poor workability. In Comparative Examples 1 and 4, since there is no essential scorch inhibitor, the Mooney scorch time is short and workability is not good. In Comparative Example 5, since no EPDM was contained, the ozone resistance was poor. In Comparative Example 7, since the amount of the filler was large, the Mooney viscosity was high, and the fluidity was low, so that molding was difficult.

[0043]

According to the present invention, it is possible to provide a vulcanized rubber having excellent ozone resistance, high durability even when used for a long period of time, and excellent moldability. Further, since the paper feeding / transporting rubber roller of the present invention is made of the vulcanized rubber, it has the above-mentioned physical properties.

[Brief description of the drawings]

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

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

[Explanation of symbols]

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

Claims (3)

[Claims] 1. A vulcanized rubber obtained by vulcanizing a rubber composition containing ethylene-propylene-diene rubber as a rubber component and having the following characteristics (1) to (3). (1) Mooney scorch time 15 at 130 ° C
(2) Vulcanization rate is 9 minutes or less at 170 ° C. (3) Mooney viscosity is 30 or less at 130 ° C. 2. A rubber component containing an ethylene-propylene-diene rubber, at least one selected from thiuram-based, thiazole-based, and sulfenamide-based vulcanization accelerators; zinc dithiocarbamate; A rubber composition comprising a vulcanization accelerator containing a metal salt of dithiocarbamic acid and a sulfonamide-based scorch inhibitor, and vulcanizing a rubber composition which may further contain a filler of 40% by weight or less of the rubber component. Vulcanized rubber. 3. A paper feed / transport rubber roller made of the vulcanized rubber according to claim 1.