Sumitomo Rubber Industries Limited

The School Corporation Kansai University

Kenichi Kuroda

Mutsuki Sugimoto

Akihiko Kawatani

Yoshihisa Mizumoto

Takashi Marui

Kei Tajima

Masakazu Tanaka

Hiroshi Tani

Takahiro Fujiwara

Kyota Sugioka

A nonporous semiconductive roller is provided, which constantly ensures proper image formation substantially without image density unevenness attributable to the roughness of an outer peripheral extrusion surface thereof when being used as a developing roller. The semiconductive roller () is made of a nonporous crosslinking product of a rubber composition which contains a rubber component including only four types of rubbers including an epichlorohydrin rubber, a chloroprene rubber, a butadiene rubber and an acrylonitrile butadiene rubber.

Semiconductive roller for image developing roller

A semiconductive roller according to the present invention includes a crosslinked product containing just the three types of rubber of butadiene rubber, epichlorohydrin rubber, and chloroprene rubber as rubber components, has a non-porous, single-layer structure, and has a compression set Cs (%) of not more than 10% as measured in accordance with the measurement method described in the Japanese Industrial Standards JIS K6262:2006 under conditions of a test temperature of 70&#xb0; C., a test time of 24 hours, and a compression ratio of 25%.

Semiconductive roller

A semiconductive roller of the present invention includes a crosslinked product of a rubber composition containing just the two types of rubber of butadiene rubber and epichlorohydrin rubber as rubber components.

A semiconductive roller is provided, which has a toner transport amount and a toner charge amount properly controlled, particularly, when being used as a developing roller, and is substantially free from imaging failure such as fogging and background smudging. The semiconductive roller is formed from a semiconductive rubber composition, and has an outer peripheral surface having a surface roughness defined by a roughness profile such that an arithmetic average roughness is not greater than 0.7 &#x3bc;m and a difference R&#x3b4;c between vertical section levels at two different load length percentages (at a load length percentage Rmr1 of 25% and a load length percentage Rmr2 of 75%) is not greater than 1.2 &#x3bc;m.

A semiconductive roller () is provided, which is formed from a rubber composition containing a rubber component including: (1) an epichlorohydrin rubber; (2) at least one solid rubber selected from the group consisting of a solid BR and a solid SBR; and (3) at least one liquid rubber selected from the group consisting of a liquid BR and a liquid SBR.

A semiconductive roller is provided which includes a roller body formed from a highly extrudable rubber composition containing an SBR and an epichlorohydrin rubber in combination as a rubber component, the roller body having a higher production yield and higher toner imaging durability, and unlikely to suffer from reduction in image density due to adhesion of toner and a contact mark on an outer peripheral surface thereof with a smaller compression set. In the rubber component, the SBR and the epichlorohydrin rubber are present in an SBR excess state. In the rubber composition, a crosslinking component for crosslinking the rubber component includes a sulfur crosslinking agent and 0.75 to 3 parts by mass of a thiazole accelerating agent based on 100 parts by mass of the rubber component. The roller body () of the semiconductive roller () is made of a crosslinking product of the rubber composition.

A semiconductive roller () according to the present invention has a nonporous single-layer structure formed from a rubber composition which includes: a rubber component including a styrene butadiene rubber and an epichlorohydrin rubber; and a salt of an anion having a fluoro group and a sulfonyl group in its molecule; the salt being present in the rubber composition in a proportion of 0.05 to 5 parts by mass based on 100 parts by mass of the overall rubber component.

An inventive developing roller is adapted for use in an electrophotographic image forming apparatus. The developing roller includes a roller body. At least an outer peripheral surface of the roller body is formed from a rubber composition containing a base rubber. The base rubber contains a styrene butadiene rubber in a proportion of not less than 10 mass % and not greater than 70 mass % based on the overall amount of the base rubber. The outer peripheral surface of the rubber body has a surface roughness Ra of not less than 0.78 &#x3bc;m and not greater than 1.8 &#x3bc;m.

Developing roller

A developing roller is provided which is capable of forming a toner layer having the most uniform possible thickness on an outer peripheral surface of a roller body thereof. The roller body () of the developing roller () is formed from a rubber composition containing a base rubber which is a mixture of NBR and/or SBR, CR, an epichlorohydrin rubber and IIR, wherein the IIR is present in a proportion of not less than 2.5 parts by mass and not greater than 20 parts by mass in 100 parts by mass of the base rubber.

A developing roller is provided which is capable of forming a toner layer having the most uniform possible thickness on an outer peripheral surface of a roller body thereof. The roller body () of the developing roller () is formed from a rubber composition comprising: a base rubber which is a mixture comprising NBR and/or SBR, CR and an epichlorohydrin rubber; and not less than 2.5 parts by mass and not greater than 15 parts by mass of a tackiness imparting agent based on 100 parts by mass of the base rubber.

The semiconductive roller according to the present invention includes a roller body having an outer peripheral surface made of a crosslinked substance of a semiconductive rubber composition and exhibiting Shore A hardness of not more than 60, the semiconductive rubber composition contains a base polymer made of a mixture of (1) mixed rubber N of liquid nitrile rubber and solid nitrile rubber, (2) chloroprene rubber C, and (3) epichlorohydrin rubber E in a mass ratio (C+E)/N of 10/90 to 80/20, the ratios of the chloroprene rubber and the epichlorohydrin rubber in the total quantity of the base polymer are not less than 5 mass % and not less than 5 mass % respectively, and roller resistance at an applied voltage of 5 V is not less than 10&#x3a9; and not more than 10&#x3a9;.

Semiconductive roller, toner transport roller and electrophotographic apparatus

A developing roller is provided, which is particularly used in an image forming apparatus of a highly durable design and is free from toner leakage even after formation of a predetermined number of images. Opposite end regions () of an outer peripheral surface () of a roller body () of the developing roller () to be respectively kept in sliding contact with seal members each have a friction coefficient &#x3bc; of not greater than 0.15.

Growing community of inventors

Kobe, Japan

Kenichi Kuroda