Patent Application
20080042108
The first embodiment of the present invention will be described below with reference to the drawings.
A conductive thermoplastic elastomer composition of the first embodiment contains a component (A) consisting of a base polymer composed of a thermoplastic elastomer composition containing a mixture of an olefin resin and a styrene thermoplastic elastomer, EPDM or/and acrylonitrile-butadiene rubber (hereinafter referred to as NBR) dynamically crosslinked and dispersed in the mixture of the olefin resin and the styrene thermoplastic elastomer; a component (B) consisting of an ionic-conductive agent containing an EO-PO-AGE copolymer and a metal salt, composed of metal cations and anions having a fluoro group and a sulfonyl group, which is contained in the EO-PO-AGE copolymer; and a component (C) consisting of an ethylene-acrylic ester-maleic anhydride copolymer.
The component (B) consisting of the ionic-conductive agent containing the EO-PO-AGE copolymer may be dynamically crosslinked.
In the component (A) consisting of the base polymer of the first embodiment, polypropylene is used as the olefin resin. A styrene-ethylene-ethylene/propylene-styrene copolymer (SEEPS) is used as the styrene thermoplastic elastomer. In the mixing ratio between the olefin resin and the styrene thermoplastic elastomer, 30 to 50 parts by mass of the olefin resin is mixed with 100 parts by mass of the styrene thermoplastic elastomer.
100 to 400 parts by mass and preferably 200 to 400 parts by mass of the crosslinkable EPDM or/and NBR is mixed with 100 parts by mass of the mixture of the styrene thermoplastic elastomer and the olefin resin.
It is favorable to use low nitrile NBR having a nitrile content at less than 25%.
The EPDM or/and the NBR are dynamically crosslinked by a resinous crosslinking agent. As the resinous crosslinking agent, halogenated alkylphenol is especially preferable.
The mixing amount of the resinous crosslinking agent is set to 5 to 15 parts by mass and preferably 10 to 15 parts by mass for 100 parts by mass of the EPDM or/and the NBR.
It is preferable that the conductive thermoplastic elastomer composition of the present invention contains 20 to 40% of the component (B) consisting of the ionic-conductive agent in a volume fraction.
It is preferable that in a mass ratio, 2 to 15 parts by mass of the ionic-conductive agent (B) is contained in 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention. It is preferable that the mixing amount of the ionic-conductive agent (B) is 3 to 25 parts by mass for 100 parts by mass of the base polymer (A).
As the metal salt, fluoroalkylsulfonic lithium is used. The mixing amount of the metal salt is set to 10 to 25 parts by mass for 100 parts by mass of the entire component (B) consisting of the ionic-conductive agent.
In the present invention, the EO-PO-AGE copolymer having a content ratio among ethylene oxide, propylene oxide, allyl glycidyl ether at 80 to 95 mol %, 1 to 10 mol %, and 1 to 10 mol % is used. It is especially preferable that the number-average molecular weight of the EO-PO-AGE copolymer is not less than 50000.
The EO-PO-AGE copolymer may be dynamically crosslinked by a peroxide.
It is preferable to use di(tert-butyl peroxy)diisopropyl benzene as the peroxide. It is preferable that the mixing amount of the peroxide is set to 0.5 to 3 parts by mass for 100 parts by mass of the EO-PO-AGE copolymer.
A crosslinking assistant may be used together with the peroxide. As the crosslinking assistant, dioximes are favorable and N,N′-m-phenylenebismaleimide is more favorable. The mixing amount of the crosslinking assistant is set to 0.1 to 5 parts by mass and favorably 0.2 to 2 parts by mass for 100 parts by mass of the EO-PO-AGE copolymer.
In the component (C) consisting of the ethylene-acrylic ester-maleic anhydride copolymer, methyl acrylate or ethyl acrylate is used as the acrylic ester. The ethyl acrylate is more favorable than the methyl acrylate.
As the mixing ratio of the monomers, the acrylic ester and the maleic anhydride composing the component (C) are set to 3 to 10 mass % and 1 to 5 mass % respectively.
In the copolymer consisting of the component (C), a melt flow rate is set to 0.5 to 100 g/10 minute and preferably 1 to 50 g/10 minutes.
The mixing amount of the component (C) consisting of the ethylene-acrylic ester-maleic anhydride copolymer is set to 0.1 to 3 parts by mass for 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention.
The mixing amount of the ethylene-acrylic ester-maleic anhydride copolymer is set to 3 to 30 parts by mass for 100 parts by mass of the component (B) consisting of ionic-conductive agent and 0.5 to 5 parts by mass for 100 parts by mass of the component (A) consisting of the base polymer.
In addition to the components (A) through (C), the conductive thermoplastic elastomer composition of the first embodiment contains a softener, calcium carbonate, carbon black, and a foaming agent if necessary.
Paraffin oil is favorable as the softener. Paraffin process oil is especially favorable. It is preferable that the mixing amount of the softener is set to the range of 50 to 200 parts by mass for 100 parts by mass of the component (A). It is also preferable that 50 to 250 parts by mass of the softener is used for 100 parts by mass of the EPDM or/and the NBR contained in the component (A).
It is preferable that the mixing amount of the calcium carbonate is set to the range of 5 to 10 parts by mass for 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention.
It is preferable that the mixing amount of the carbon black is set to the range of 1 to 10 parts by mass for 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention.
The foaming agent of the micro-capsule type is preferable. It is preferable that the mixing amount of the foaming agent is set to the range of 0.5 to 5 parts by mass for 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention.
The conductive thermoplastic elastomer composition of the first embodiment is produced by the following method:
Initially the EPDM or/and the NBR are pelletized. The pelletized EPDM or/and NBR, the styrene thermoplastic elastomer, the olefin resin, the crosslinking agent, and the softener are kneaded at 200° C. to form a pellet of the thermoplastic elastomer composition as the component (A) consisting of the base polymer.
The obtained pellet of the component (A) consisting of the thermoplastic elastomer composition, the component (B) consisting of the ionic-conductive agent, the component (C) consisting of the ethylene-acrylic ester-maleic anhydride copolymer, the calcium carbonate, the carbon black, and the foaming agent used if necessary are kneaded at 200° C. to obtain a pellet of the conductive thermoplastic elastomer composition of the present invention.
When the EO-PO-AGE copolymer contained in the component (B) consisting of the ionic-conductive agent is dynamically crosslinked by the peroxide, the peroxide and the crosslinking assistant are kneaded together with the component (B) consisting of the ionic-conductive agent.
A conductive roller of the first embodiment is obtained by molding the conductive thermoplastic elastomer composition of the present invention.
A conductive roller 10 of the first embodiment is shown in
The conductive roller 10 is composed of a cylindrical roller part 11 made of the conductive thermoplastic elastomer composition and a columnar metal shaft 12.
The conductive roller 10 is produced by tubularly extruding the pelletized conductive thermoplastic elastomer composition at 180 to 230° C. by using a single-screw extruder and thereafter inserting the metal shaft 12 into a hollow portion of the roller part 11 by press fit or bonding the shaft 12 to the roller part 11 with an adhesive agent. It is possible to produce an approximately D-shaped rubber roller by inserting an approximately D-shaped shaft into the hollow portion of the cylindrically shaped roller part by press fit.
A coating layer (not shown) may be formed on the surface of the conductive roller 10.
The electric resistance value of the conductive roller 10 produced by the above-described method is set to favorably the range of 104Ω to 109Ω and more favorably the range of 106Ω to 108Ω when 1000V is applied thereto.
The second embodiment is described below.
The second embodiment is different from the first embodiment in that the conductive thermoplastic elastomer composition of the second embodiment contains the polyester thermoplastic elastomer in addition to the components (A) through (C) of the conductive thermoplastic elastomer composition of the first embodiment.
The conductive thermoplastic elastomer composition of the second embodiment contains the component (A) consisting of the base polymer composed of the thermoplastic elastomer composition containing the mixture of the olefin resin and the styrene thermoplastic elastomer, the EPDM or/and the NBR dynamically crosslinked and dispersed in the mixture of the olefin resin and the styrene thermoplastic elastomer; the component (B) consisting of the ionic-conductive agent containing the EO-PO-AGE copolymer and the metal salt, composed of the metal cations and the anions having the fluoro group and the sulfonyl group, which is contained in the EO-PO-AGE copolymer; the component (C) consisting of the ethylene-acrylic ester-maleic anhydride copolymer; and the polyester thermoplastic elastomer.
As the component (D) consisting of the polyester thermoplastic elastomer, a copolymer composed of a hard segment consisting of polybutylene terephthalate and a soft segment consisting of polyether is used.
The mixing amount of the component (D) consisting of the polyester thermoplastic elastomer is set to 1 to 10 parts by mass for 100 parts by mass of the conductive thermoplastic elastomer composition of the present invention, 1 to 10 parts by mass for 100 parts by mass of the component (A), and 30 to 120 parts by mass for 100 parts by mass of the component (B).
The mixing amount of the component (C) is set to 10 to 40 parts by mass for 100 parts by mass of the component (D)
In the second embodiment, the pellet of the component (A) obtained by carrying out a method similar to that of the first embodiment, the component (B), the component (C), the component (D), the calcium carbonate, the carbon black, and the foaming agent which is used if necessary were kneaded at 200° C. to obtain the pellet of the conductive thermoplastic elastomer composition.
The other constructions and effects of the second embodiment are similar to those of the first embodiment. Thus the description thereof is omitted herein.
Examples of a paper-feeding roller of the present invention and comparison examples are described below.
Compositions in which components and mixing ratio thereof are shown in tables 1 through 6 were tubularly extruded to obtain moldings. A shaft was inserted into each molding to prepare conductive rollers. Examinations were conducted on the obtained conductive rollers.
Except that components of the compositions of the examples and the comparison examples were different, the conductive rollers of the examples 1 through 9 and those of the comparison examples 1 through 6 were produced in a method similar to that of the first embodiment, and the conductive rollers of the examples 10 through 25 and those of the comparison examples 7 through 16 were produced in a method similar to that of the second embodiment.
Materials used are as shown below:
EPDM oil-extended at 100% was used. The amount of the oil of the oil-extended EPDM is included in the mixing amount of the softener shown in the tables. In the tables, only the value of the rubber component is shown in the space of the EPDM. When the EPDM was used at 100 parts by mass and the softener was used at 174 parts by mass, the extended oil deriving from the oil-extended EPDM was used at 100 parts by mass and the remaining softener commercially available shown below was used at 74 parts by mass.
EPDM: “Esprene 670F (commercial name)” produced by Sumitomo Chemical Co, Ltd. (paraffin oil 100% oil-extended)
NBR: “DN401LL (commercial name)” produced by Zeon Corporation
SEEPS: hydrogenated styrene thermoplastic elastomer (“Septon 4077 (commercial name)” produced by Kuraray Co., Ltd.)
PP: polypropylene resin (“Novatech PP (commercial name)” produced by Japan Polychem Corporation)
Crosslinking agent: resinous crosslinking agent consisting of halogenated alkylphenol (“TACKROL 250-III (commercial name)” produced by TAOKA CHEMICAL CO., LTD.)
Softener: paraffin oil: “Diana process oil PW-380 (commercial name)” produced by Idemitsu Kosan Co., Ltd.
Calcium carbonate: “BF300 (commercial name)” produced by Shiraishi Calcium Kaisha, Ltd.
Carbon black: “SEAST 3 (commercial name)” produced by Tokai Carbon Co., Ltd.
Compatibilizing agent: ethylene-acrylic ester-maleic anhydride copolymer (“Bondine LX4110 (commercial name)” (produced by Arkema Co., Ltd.)
Conductive agent 2: polyether polyolefin copolymer (“PELESTAT 300 (commercial name)” produced by Sanyo Chemical Industries, Ltd.) and trifluoromethanesulfonic lithium (produced by Sanko Chemical Co., Ltd.), mixing ratio between polyether polyolefin copolymer and trifluoromethanesulfonic lithium was 20:1 in mass ratio.
Conductive agent 3: polyether block amide copolymer (“IRGASTAT P18 (commercial name)” produced by Chiba-Specialty-Chemicals Co., Ltd.) and trifluoromethanesulfonic lithium (produced by Sanko Chemical Co., Ltd.), mixing ratio between polyether block amide copolymer and trifluoromethanesulfonic lithium was 9:1 in mass ratio.
Peroxide: di(tert-butyl peroxy)diisopropyl benzene (“PERBUTYL P (commercial name)” produced by NOF Corporation)
Crosslinking assistant: N,N′-m-phenylene bismaleimide (“Actor PBM-R (commercial name)” produced by KAWAGUCHI CHEMICAL INDUSTRY CO., LTD.)
TPEE: polyester thermoplastic elastomer (“Hytrel 3078 (commercial name)” produced by Du Pont-Toray Co., Ltd.)
Foaming agent: “MB170EVA65 (commercial name)” (produced by Matsumoto Yushi Seiyaku Co., Ltd.)
The producing method is as described below.
Used as the component (A) consisting of the base polymer was the thermoplastic elastomer composition (SEEPS) in which the EPDM or/and the NBR were dynamically crosslinked with the resinous crosslinking agent and dispersed in the mixture of the styrene thermoplastic elastomer (SEEPS) and the polypropylene resin (PP) was used.
The EPDM and the NBR were pelletized. The pelletized EPDM or/and NBR, the styrene thermoplastic elastomer, the polypropylene resin, the crosslinking agent, and the softener were mixed with one another at the mixing ratio shown in the tables. After the components were dry-blended by a tumbler, the components were kneaded at 200 rpm and at 200° C. by using a twin-screw extruder (“HTM 38 (commercial name)” produced by I-pec Inc.) to form a pellet of the thermoplastic elastomer composition.
The following components were mixed with one another at the mixing ratio shown in the tables. The components were the obtained pelletized thermoplastic elastomer composition, the calcium carbonate, the carbon black, the ethylene-acrylic ester-maleic anhydride copolymer serving as the compatibilizing agent, the ionic-conductive agent, the polyester thermoplastic elastomer (TPEE) which is used if necessary, and additives (which are used if necessary) such as the peroxide, the crosslinking assistant, and the foaming agent. After the components were dry-blended by a tumbler, they were kneaded at 200 rpm and at 200° C. by using the twin-screw extruder (“HTM 38 (commercial name)” produced by I-pec Inc.) to obtain the pellet of the conductive thermoplastic elastomer composition of the present invention.
The obtained pellet of the conductive thermoplastic elastomer composition was tubularly extruded by using a single-screw extruder (φ50 extruder produced by San NT Inc.) at 20 rpm and at 200° C. to obtain a molding of each of the examples and the comparison examples having an outer diameter of 12 mm and an inner diameter of 5 mm.
A shaft was inserted into each of the obtained tubes to obtain the conductive rollers of the present invention.
A coating was formed on the surface of the conductive roller of each of the examples 7, 8, 16, 17, 24, and 25. More specifically, a coating additive (“JLY-009 (commercial name)” produced by Acheson Japan Ltd.) was sprayed thereon. Thereafter the coating additive was baked at 150° C. for 10 minutes.
Measurement of Electric Resistance Value of Roller
The following examinations were conducted on the obtained conductive rollers.
As Shown in
Stability at High Temperature and Humidity
The conductive rollers were stored at a high temperature of 30° C. and a high relative humidity of 80%. The electric resistance values of conductive rollers were measured by the above-described method a week later. The electric resistance values thereof were measured every one week with the conductive rollers stored at the high temperature and the high humidity for one month.
Conductive rollers whose electric resistance values gradually decreased within one month and were unstable were evaluated as “gradually decreased”. Conductive rollers whose electric resistance values were stable were evaluated as “unchanged”.
Of the conductive rollers whose electric resistance values became stable within one month, those of the examples 2, through 25 were evaluated on the stability of the electric resistance values thereof at the high temperature and humidity, as described below. Results are shown in the tables.
The conductive rollers were stored for one day at the high temperature of 30° C. and the high relative humidity of 80%. Thereafter the electric resistance values thereof were measured by the above-described method. Normally, when the conductive rollers are subjected to a high temperature and a high relative humidity, the electric resistance values thereof become lower. The conductive rollers were stored for one day at the high temperature and the high humidity and the electric resistance values thereof were measured until the electric resistance values thereof did not drop and became stable at a constant value.
The number of days until the electric resistance value of each roller became stable is shown in the tables. Conductive rollers whose electric resistance values became stable in fewer days were more favorable than those whose electric resistance values became stable in more days. More specifically, conductive rollers whose electric resistance values became stable within three days were evaluated as being favorable. conductive rollers whose electric resistance values became stable within one day were evaluated as being especially favorable.
Printing Test
The conductive rollers of the examples and the comparison examples were mounted on a printer (“C5200n” manufactured by Oki Data Co., Ltd.) commercially available or an attachment cartridge (black) as a transfer roller or a charging roller.
Printing was performed on 50 sheets at a temperature of 23° C. and a relative humidity of 55%. Printing density and unevenness of printing of the 50 sheets were visually checked.
As apparent from the tables, in the conductive thermoplastic elastomer composition of the comparison examples 1, 4, 6, 7, 10, 12, and 15 not containing the ethylene-acrylic ester-maleic anhydride copolymer serving as a compatibilizing agent, the ionic-conductive agent did not compatibilize. Thus the conductive thermoplastic elastomer composition could not be extruded.
In the conductive thermoplastic elastomer composition of the comparison examples 2, 3, 5, 8, 9, 11, 13, 14, and 16 using polymers other than the EO-PO copolymer or/and the EO-PO-AGE copolymer contained in the ionic-conductive agent, although extrusion molding could be made favorably, the stability of the electric resistance values thereof at the high temperature and humidity was unfavorable, i.e., the electric resistance values thereof became gradually low. When they were incorporated in the printer as the transfer roller, printing concentration gradually became thicker. Thus it was confirmed that they left room for improvement to such an extent they can be put into practical use.
On the other hand, the conductive thermoplastic elastomer compositions of the examples could be extruded favorably, and the stability of the electric resistance values thereof at the high temperature and humidity was favorable. Thus the electric resistance values thereof did not change. When the conductive rollers were incorporated in the printer as the transfer roller or the charging roller, printing concentration was stable. Thus it was confirmed that they could be reliably put into practical use.
The conductive rollers of the examples 7, 8, 16, 17, 24, and 25 on which the coating was formed had a low coefficient of friction.
The conductive thermoplastic elastomer compositions of the examples 10 through 25 containing the polyester thermoplastic elastomer became stable more rapidly in the electric resistance values thereof than that of the conductive thermoplastic elastomer composition of the example 2 which did not contain the polyester thermoplastic elastomer and were very stable in the electric resistance values thereof at the high temperature and humidity. It was confirmed that the conductive roller composed of the conductive thermoplastic elastomer composition containing the polyester thermoplastic elastomer was very stable at the high temperature and humidity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-221858 | Aug 2006 | JP | national |
| 2006-221908 | Aug 2006 | JP | national |
