JP2005061467A - Sponge rubber roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sponge rubber roll of low hardness and high durability. <P>SOLUTION: In this sponge rubber roll of low hardness using EPDM rubber, EPDM crude rubber having Mooney viscosity ML<SB>1+4</SB>(100°C) of 50 or more is used when the EPDM crude rubber is non-oil extended rubber and includes ethylene by 58% or more, and that having Mooney viscosity ML<SB>1+4</SB>(100°C) of 80 or more is used when a content of ethylene is less than 58%, a foam substantially not including a reinforcement agent is used, and an average cell diameter of the foam medium is 400μm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sponge rubber roll, and particularly suitable for use in transfer, development rolls, various paper feeds and transport rolls for various OA devices such as copying machines, facsimiles, and various printers. It is.

  Conventionally, EPDM rubber has been conventionally used as a roll for transfer, development, or paper feeding / conveying of various OA devices (see Patent Documents 1 and 2, etc.). However, as described in these documents, it is necessary to add a large amount of a softening agent in order to reduce the hardness of the solid rubber, and there are problems in terms of contamination due to bleeding and durability. On the other hand, a low hardness may be obtained by using a sponge, that is, a foam. When producing such a low-hardness sponge rubber roll, it is relatively easy to reduce the hardness by using a polymer having a relatively low Mooney viscosity. . In this case, even if a filler such as carbon is added, the durability depends on the polymer, so that there is a problem that the hardness is not improved. In addition, in order to obtain high durability, a material having a relatively high hardness can be obtained by a free foaming method using a material with a high Mooney viscosity. As a result, the durability characteristics are deteriorated, the appearance is impaired, the durability and various functions are deteriorated due to the mixing of paper dust and the like, and the setability is deteriorated.

JP-A-5-77508

Japanese Patent Application Laid-Open No. 7-242799

  In view of such circumstances, an object of the present invention is to provide a sponge rubber roll having low hardness and excellent durability.

  As a result of intensive research to solve the above problems, the present inventor uses a polymer having a high Mooney viscosity, and if necessary, adds a thermoplastic resin in a predetermined composition, and finely foams under a predetermined condition. As a result, a new finding was obtained that a sponge rubber roll having low hardness and high durability could be obtained without adding a reinforcing agent, and the present invention was completed.

In the first aspect of the present invention, the low hardness sponge rubber roll using EPDM rubber has a Mooney viscosity ML _{1 + 4} (100 ° C.) of 50 or more when the EPDM raw rubber is non-oil extended and the ethylene content is 58% or more. When the ethylene content is less than 58%, a Mooney viscosity ML _{1 + 4} (100 ° C.) of 80 or more is used, and a foam is obtained without substantially adding a reinforcing agent. The sponge rubber roll has a cell diameter of 400 μm or less.

  A second aspect of the present invention is the sponge rubber roll according to the first aspect, wherein 40 parts by weight or less of a softening agent is added to 100 parts by weight of the EPDM raw rubber.

  A third aspect of the present invention is the sponge rubber roll according to the first or second aspect, wherein the rubber hardness is 40 ° or less in Asker C.

  A fourth aspect of the present invention is the sponge rubber roll according to any one of the first to third aspects, wherein 10 parts by weight or less of a thermoplastic resin is blended with 100 parts by weight of the EPDM raw rubber.

  According to a fifth aspect of the present invention, there is provided a sponge rubber roll according to the fourth aspect, wherein the thermoplastic resin is polyethylene.

  The present invention uses a raw rubber having a high Mooney viscosity and foams it under a pressure environment, so that it does not use a large amount of a softening agent and does not substantially use a reinforcing agent for enhancing durability, and has a low hardness and a high hardness. The effect is to provide a durable sponge rubber roll.

The sponge rubber roll of the present invention is obtained by foaming under a predetermined condition using an EPDM raw rubber having a high Mooney viscosity. Here, the high Mooney viscosity EPDM raw rubber is a non-oil-extended raw rubber having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 50 or higher when the ethylene content is 58% or higher, or the ethylene content. Is less than 58%, the Mooney viscosity ML _{1 + 4} (100 ° C.) is 80 or more. Here, the EPDM rubber refers to an ethylene propylene diene copolymer, but includes all those commercially available as EPDM. Even if the Mooney viscosity of the raw rubber in a substantially oil-extended state is within the above-mentioned range, the effect of the present invention cannot be obtained, but the above-mentioned high Mooney viscosity raw rubber is used, and a softener is added thereto. Even if the addition amount of the softening agent is 40 parts by weight or less, the effect of the present invention can be obtained.

  Here, the softening agent is not particularly limited as long as it is compatible with EPDM, and paraffinic oil or aromatic oil having SP value close to that of EPDM and compatible can be exemplified. Considering the properties, it is preferable to use paraffinic oil.

  The sponge rubber roll of the present invention may be added with other additives such as foam stabilizers, anti-aging agents, antioxidants, etc., as well as foaming agents, foaming aids, etc. A reinforcing agent is not added. Here, the fact that a reinforcing agent is not substantially added means that a reinforcing agent such as carbon or silica is not specially blended, and does not exclude the case where a small amount is added together with other additives. .

  The sponge rubber roll of the present invention has an average cell diameter of 400 μm or less. When the average cell diameter is larger than 400 μm, the appearance is deteriorated, and paper dust and the like are mixed, and the durability and functions according to the application such as curl removal, paper feeding, and transportability are lowered. Lowers the start-up performance at start-up. The cell diameter also affects the durability, and is preferably 150 μm or less.

  Thus, in order to prevent the enlargement of the cell and ensure the durability, it is necessary to prevent the cell from becoming enlarged and to foam, and it is preferable to foam in an environment loaded with a desired pressure. Further, since the cell diameter varies greatly depending on the type and blending amount of the foaming agent and foaming aid, it is necessary to select conditions appropriately. It can also be manufactured to adjust the foaming rate and rubber hardness by independently controlling the temperature and pressure conditions during vulcanization of the foam material, and this manufacturing method is a patent application filed earlier. (Japanese Patent Application No. 2003-113317).

  The sponge rubber roll of the present invention preferably has a rubber hardness of 40 ° or less in Asker C. This is to obtain the intended low hardness and high durability sponge rubber roll.

  In the sponge rubber roll of the present invention, 10 parts by weight or less of a thermoplastic resin may be blended with 100 parts by weight of EPDM raw rubber. Here, the thermoplastic resin typically refers to a polyolefin resin such as polyethylene and polypropylene, but any thermoplastic resin that melts during vulcanization (crosslinking) can be used. Therefore, it is preferable to use a thermoplastic resin having a melting point of 170 ° C. or lower.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these Examples do not limit the scope of the present invention at all.

(Example 1)
To 100 parts by weight of EPDM raw rubber (EPDM (66% / 90)) having an ethylene content of 66% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 90 parts, 10 parts by weight of polyethylene having a molecular weight of 2 million is added and oxidized as an additive. Add 5 parts by weight of zinc and 1 part by weight of stearic acid, add 12 parts by weight of foaming agent, 7 parts by weight of foaming aid, 1.6 parts by weight of sulfur and 35 parts by weight of paraffinic oil, knead and rubber Foam molding was performed aiming at 25 ° with a hardness Asker C. Vulcanization was performed in an autoclave.

(Example 2)
Except that 5 parts by weight of polyethylene having a molecular weight of 50,000 was blended, it was blended and kneaded in the same manner as in Example 1, and foam-molded with a rubber hardness Asker C aimed at 25 °. Vulcanization was performed in an autoclave.

(Example 3)
As polyethylene, 10 parts by weight of a molecular weight of 3000 is blended and 30 parts by weight of a softening agent, paraffinic oil, is blended and kneaded in the same manner as in Example 1, aiming at a rubber hardness Asker C of 25 °. Was foam molded. Vulcanization was performed in an autoclave under the same conditions.

Example 4
Except that polyethylene was not blended and 25 parts by weight of paraffinic oil as a softening agent was used, blending and kneading were carried out in the same manner as in Example 1, and foam molding was performed with a rubber hardness Asker C aimed at 25 °. Vulcanization was performed in an autoclave under the same conditions.

(Example 5)
To 100 parts by weight of EPDM raw rubber (EPDM (67% / 71)) having an ethylene content of 67% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 71, 5 parts by weight of zinc oxide and 1 part by weight of stearic acid were added. Furthermore, 12 parts by weight of a foaming agent, 7 parts by weight of a foaming aid, 1.6 parts by weight of sulfur, and 20 parts by weight of paraffinic oil were added, kneaded, and foam-molded with a rubber hardness Asker C aimed at 25 °. Vulcanization was performed in an autoclave under the same conditions.

(Example 6)
EPDM raw rubber Mooney viscosity _ML 1 + 4 at an ethylene content of 67% (100 ° C.) is 38 (EPDM (67% / 38 )) Mooney 50 parts by weight and the ethylene content 67% Viscosity _ML 1 + 4 (100 ° C.) is 71 EPDM Blend with 50 parts by weight of raw rubber (EPDM (67% / 71)) (ethylene content 67%, Mooney viscosity ML _{1 + 4} (100 ° C.) 50-60, about 54), 5 parts by weight of zinc oxide and stearin as additive 1 part by weight of acid was added, and further 12 parts by weight of foaming agent, 7 parts by weight of foaming aid, 1.6 parts by weight of sulfur and 15 parts by weight of paraffinic oil were added and kneaded, and the rubber hardness Asker C was 25 °. Foam molding was aimed at. Vulcanization was performed in an autoclave under the same conditions.

(Example 7)
To 100 parts by weight of EPDM raw rubber (EPDM (59% / 90)) having an ethylene content of 59% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 90 parts, 5 parts by weight of zinc oxide and 1 part by weight of stearic acid were added. Further, 12 parts by weight of a foaming agent, 7 parts by weight of a foaming aid, 1.6 parts by weight of sulfur, and 25 parts by weight of paraffinic oil were added, kneaded, and foam-molded with a rubber hardness Asker C aimed at 25 °. Vulcanization was performed in an autoclave under the same conditions.

(Example 8)
EPDM was blended and kneaded in the same manner as in Example 7 except that EPDM raw rubber (EPDM (54% / 105)) having an ethylene content of 54% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 105 was used. Foam molding was performed aiming at 25 ° with a hardness Asker C. Vulcanization was performed in an autoclave under the same conditions.

Example 9
The EPDM was blended and kneaded in the same manner as in Example 7 except that an EPDM raw rubber (EPDM (56% / 86)) having an ethylene content of 56% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 86 was used. Foam molding was performed aiming at 25 ° with a hardness Asker C. Vulcanization was performed in an autoclave.

(Example 10)
The composition was the same as in Example 4 except that 3 parts by weight of the organic foaming agent, 2 parts by weight of the foaming aid, and 3 parts by weight of the inorganic foaming agent were used. Vulcanization was performed in an autoclave under the same conditions.

(Comparative Example 1)
To 100 parts by weight of EPDM raw rubber (EPDM (67% / 38)) having an ethylene content of 67% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 38, 5 parts by weight of zinc oxide and 1 part by weight of stearic acid were added. Furthermore, 12 parts by weight of a foaming agent, 7 parts by weight of a foaming aid, 1.6 parts by weight of sulfur, and 5 parts by weight of paraffinic oil were added, kneaded, and foam-molded with a rubber hardness Asker C aimed at 25 °. Vulcanization was performed in an autoclave under the same conditions.

(Comparative Example 2)
As EPDM, an EPDM raw rubber (EPDM (54% / 74)) having an ethylene content of 54% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 74 was used, and the paraffinic oil as a softening agent was changed to 20 parts by weight. Same as Comparative Example 1.

(Comparative Example 3)
Example 4 was repeated except that 35 parts by weight of carbon was added as a reinforcing agent and 75 parts by weight of paraffinic oil as a softening agent was added.

(Comparative Example 4)
The procedure was the same as Example 4 except that 20 parts by weight of paraffinic oil as a softening agent was used and free foaming was performed without using an autoclave during vulcanization.

(Comparative Example 5)
The composition was the same as Example 10 except that 6 parts by weight of the organic foaming agent, 5 parts by weight of the foaming aid, and 2 parts by weight of the inorganic foaming agent were used. Vulcanization was performed in an autoclave under the same conditions.

(Test example)
About the foam of each Example and the comparative example, rubber hardness (Asker C), the average cell diameter, the expansion ratio, and the amount of wear were measured.

  In addition, the cell diameter was taken as the average which measured 10 pieces at random with the microscope picture of 100 time.

  Further, the expansion ratio was obtained from the following formula.

Foaming ratio = density of vulcanized rubber after foaming (g / cm ³ ) / density of rubber before vulcanization without blowing agent (g / cm ³ )

Furthermore, the amount of wear (cm ³ ) was measured with an endurance tester as shown in FIG. That is, the sponge rubber rolls of the examples and comparative examples were cut to a predetermined length to produce a roll having an outer diameter of 22 mm, an inner diameter of 9 mm, and a length of 23 mm. The sponge rubber roll 11 was made into an opposing roll 12 made of polyamide. The test paper 13 is sandwiched between them, a test load of 400 g is applied between the rolls, and the test paper 13 is fed by the test paper feed roll 14 in the arrow direction A at a speed of 1 mm / s, and a sponge rubber roll. 11 was rotated in the direction of arrow B at 600 rpm, and the amount of wear after 100,000 rotations was measured. The amount of wear was calculated from the following equation.

Abrasion amount = [weight before test (g) −weight after test (g)] / density of sponge rubber roll used (g / cm ³ )

  These results are shown in Table 1-1 and Table 1-2 together with the formulation.

  Further, EPDM used in Examples and Comparative Examples is divided into ethylene content of 58% or more and less than 58%, and the relationship between Mooney viscosity and wear amount is shown in FIG. 2 and FIG.

As a result, when EPDM having an ethylene content of 58% or more was used, the wear amount was 0.2 cm ³ or less in Examples 6, 5, 7, and 4 in which the raw rubber Mooney viscosity exceeded 50. Although excellent in durability, it was found that in Comparative Example 1 having a Mooney viscosity of 38, rubber peeling occurred and the durability was remarkably inferior. On the other hand, when EPDM having an ethylene content of less than 58% is used, in Examples 9 and 8 where the raw rubber Mooney viscosity exceeds 80, the wear amount is 0.2 cm ³ or less and the durability is excellent. However, in Comparative Example 2 with 74, the wear amount was close to 0.6 cm ^3, and it was found that the durability was extremely inferior. Further, even in the same formulation as in Example 4, when the pressure during vulcanization was reduced and the average cell diameter was 334 μm (Example 10), the wear amount was 0.2 cm ³ or less, and there was no problem in durability. However, in the case of free foaming with an average cell diameter of 480 μm (Comparative Example 4) and with a low pressure and an average cell diameter of 434 μm (Comparative Example 5), rubber peeling occurs and the wear amount is 0.3 cm ^3. It was large as described above, and it was found that the durability was remarkably inferior. Furthermore, it has been found that when carbon is added as a reinforcing agent, the hardness can be reduced if a large amount of softening agent is added (Comparative Example 3), but naturally a problem of contamination occurs.

  On the other hand, when polyethylene is added (Examples 1 to 3), the average cell diameter tends to be small, and particularly when high molecular weight polyethylene is added, the amount of wear is remarkably reduced and greatly contributes to improvement in durability. I understood it.

It is a figure which shows the mode of wear amount measurement. It is a figure which shows the relationship between the Mooney viscosity and the amount of wear in a test example. It is a figure which shows the relationship between the Mooney viscosity and the amount of wear in a test example.

Explanation of symbols

11 Sponge rubber roll 12 Opposite roll 13 Test paper 14 Test paper feed roll

Claims (5)

In a low hardness sponge rubber roll using EPDM rubber, when the EPDM raw rubber is non-oil extended and the ethylene content is 58% or more, the Mooney viscosity ML _{1 + 4} (100 ° C.) is 50 or more, or the ethylene content is 58%. When the viscosity is less than ₁ , a Mooney viscosity ML _{1 + 4} (100 ° C.) of 80 or more is used, and a foam is obtained without substantially adding a reinforcing agent, and the average cell diameter of the foam is 400 μm or less. And sponge rubber roll. The sponge rubber roll according to claim 1, wherein 40 parts by weight or less of a softening agent is added to 100 parts by weight of the EPDM raw rubber. The sponge rubber roll according to claim 1 or 2, wherein the rubber hardness is 40 ° or less in Asker C. The sponge rubber roll according to any one of claims 1 to 3, wherein 10 parts by weight or less of a thermoplastic resin is blended with 100 parts by weight of the EPDM raw rubber. 5. The sponge rubber roll according to claim 4, wherein the thermoplastic resin is polyethylene.

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