JPH0940712A - Method for modifying peroxide-crosslinkable fluororubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified peroxide-crosslinkable fluororubber having improved affinity for silicone oil and giving especially a long-life thermocompressive fixing roll of a dry electrostatic duplicator. SOLUTION: A peroxide-crosslinkable fluororubber is reacted with at least one methylsiloxane compound containing an Si-bonded ethylenically unsaturated group, a halogen atom and/or a hydrogen atom as reactive groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the affinity of peroxide-crosslinked fluororubber with silicone oil. Further, the present invention has a vulcanized product of a peroxide vulcanizable fluororubber having improved affinity for silicone oil by the above method as a non-adhesive coating layer, and is particularly suitable for use as a hot pressure fixing roll of a dry electronic copying machine. Regarding the roll.

Conventionally, as a fixing system of a dry electrostatic copying machine, a heat pressure fixing using a heat roll having a metal core and a non-adhesive coating layer is generally adopted. Examples of materials for the non-adhesive coating layer of this hot-press roll include fluororesin (USP 3 268 351), dimethyl silicone rubber (USP 3 666 247, JP-A-52-46).
819), phenyl silicone rubber (JP-A-59-2)
09129), fluorosilicone rubber (JP-A-3-
26947), fluororubber (JP-A-55-13587).
No. 6) and the like have been proposed, and some have been put to practical use.

However, since these materials are not sufficiently non-adhesive to the dry developing toner, in order to extend the durable life of the fixing roll, a so-called oil fuse system in which silicone oil is constantly supplied to the roll surface is used. Have been forced to adopt.

Fluororesin-coated rolls generally show good non-adhesiveness and do not necessarily require the supply of silicone oil, but they have the drawback of giving the copy surface an unnecessary gloss because of its hard surface and poor rubber elasticity. Also, when silicone oil is used, uneven fixing occurs due to oil repellency. The dimethyl silicone rubber coated roll swells when the dimethyl silicone absorbs silicone oil when it is hot,
It deteriorates early and becomes unusable. Although the phenyl silicone rubber coating has improved resistance to silicone oil, its non-adhesiveness to toner tends to decrease.
The fluorosilicone rubber coating has sufficient resistance to silicone oil, but is poor in non-adhesiveness, heat resistance and physical strength, and its maximum use temperature is about 180 ° C.,
It cannot be used at the roll surface temperature of 230 ° C. of the heat-pressure fixing roll required for the current high-speed copying machine.

Further, the fluororubber coating withstands a temperature of 270 ° C. which is normally used and is not attacked by hot silicone oil at all, but has poor non-adhesiveness to toner and is poorly compatible with silicone oil. Need supply. Therefore, various attempts have been made to improve the affinity of fluororubber with silicone oil. For example, compounding of fluororubber with amino-modified silicone oil (JP-A-3-285934) and post-treatment of fluororubber with amino-modified silicone oil ( JP-A-6-175532
No.), treatment with mercapto-modified silicone oil (JP-A-59-4699), modification with other organosiloxanes (JP-A-4-308878, JP-A-4-3).
No. 08879) has been proposed. Further, a blend of fluororubber and silicone rubber, a copolymer type of fluororubber and silicone rubber, and the like have been proposed, but all of them have problems.

[0006] For example, in the case of blending modified silicone oil or post-treatment with modified silicone oil, the amino-modified silicone oil and mercapto-modified silicone oil used have poor heat resistance, so that they themselves gradually increase at a normal temperature of around 230 ° C. It is thermally deteriorated and loses its affinity with silicone oil, resulting in adhesion of toner and winding of paper, and at the same time, over-vulcanization of the fluororubber, and the fluororubber coating layer collapses and peels from the core. In addition, these modified silicone oils have hygiene problems.
Further, a blend of fluororubber and silicone rubber is difficult to process, and a copolymerization type of both has not been put to practical use.

[0007]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a method for improving the affinity of a peroxide-crosslinked fluororubber with a silicone oil without impairing its excellent non-tackiness, high rubber elasticity and heat resistance. It is in. Another object of the present invention is to provide a roll having excellent non-adhesiveness, high rubber elasticity, and heat resistance, and a significantly improved silicone oil affinity, which shows excellent performance as a heat and pressure fixing roll of a dry type electronic copying machine. To provide.

[0008]

According to the present invention. In order to achieve the above object, at least one kind of a methylsiloxane compound containing a group having an ethylenically unsaturated bond bonded to a silicon atom as a reactive group, a halogen atom and / or a hydrogen atom is reacted with a peroxide-crosslinked fluororubber. In a preferred embodiment of the present invention, this reaction is carried out simultaneously with vulcanization by blending the unvulcanized peroxide-crosslinked fluororubber composition with the methylsiloxane compound. Alternatively, it may be carried out by means of coating or impregnating the surface of the unvulcanized, semi-vulcanized or vulcanized peroxide-crosslinked fluororubber molded article with the above-mentioned methylsiloxane compound to cause a reaction.

The embodiments of the present invention will be described in detail below. As a cross-linking method for fluororubbers, amine cross-linking, polyol cross-linking, peroxide cross-linking and other cross-linking methods utilizing the characteristics of polymers have been developed, and polymers suitable for each cross-linking method have also been developed.

The peroxide type fluororubber to be used in the present invention is a vinylidene fluoride-hexalolopropylene copolymer, a vinylidene fluoride-hexalolopropylene-tetrafluoroethylene copolymer or a tetrafluoroethylene-propylene copolymer. In a fluororubber of the type in which halogen, especially bromine and / or iodine, and hydrogen atoms are introduced into the polymer molecular chain end and side chain, the crosslinking is carried out by abstraction reaction of halogen atoms and hydrogen atoms. In the practice of the present invention, the rubber composition is crosslinked by a conventional method, that is, using a radical generator represented by an organic peroxide compound and a crosslinking aid, generally triallyl isocyanurate, as a crosslinking agent.

The group having an ethylenically unsaturated bond bonded to a silicon atom, a methylsiloxane compound containing a halogen atom and / or a hydrogen atom as a reactive group used in the practice of the present invention is not particularly limited. The compounds shown in are preferably used (the compounds shown below are all products of Shin-Etsu Chemical Co., Ltd., and symbols consisting of alphanumeric characters are product names of the same). A) methyl includes groups with an ethylenically unsaturated bond siloxane _{R-Si (CH 3) 2} O [Si (CH 3) 2 O ] _n Si (CH _{3) 2} -
RR contains an isopropenyl group and is S by a C-Sik bond.
Organic group attached to i atom (no further details available)
X-22-164B, X-22-164C CH 2 = CCH 3 COOC 3 H 3 H 6 Si- (OSi CH
_{3) 3 X-22-5002 (CH} 3) 3 Si O _{[Si (CH 3) 2 O]} n Si (CH 3) 2 -R
_{X-22-174D (CH 3) 3} Si O (Si HCH 3 O) 2 Si (CH 3) 3
LS-8630 _{[(CH 3) 3 SiO] 3} Si H LS-8650 - (Si HCHO) n - methylsiloxane [(CH ₃ including KF-99 B) reactive halogen _{atoms) 3 Si O] 3 Si (} CH ₂ ) ₃ I LS-870
0 C) methylsiloxane containing reactive hydrogen atoms _{[HSi (CH 3) 2] 2} O LS-7040 _{[HSi (CH 3) 2 O]} 2 Si (CH 3) 2 LS-8130 HSi (CH 3) 2 OSi the (CH _{3) 3-methyl-siloxane} compound preferably used in the LS-7060 present invention, a group having an ethylenically unsaturated bond, with a reactive halogen atom and / or a reactive hydrogen atom, chloro, chloroalkyl, phenyl , Polyether, methyl styryl, cyanoalkyl, trifluoropropyl, perfluoroalkyl, and the like, also include methylsiloxane compounds having a terminal and / or side chain containing a non-reactive group, and needless to say, a mixture thereof is also appropriate. Can be used for

The mixing ratio of the above-mentioned methyl siloxane compound to the peroxide-crosslinking fluororubber is not particularly limited, and is generally 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the former. Further, the amount of the peroxide-crosslinked fluororubber molded article applied or impregnated on the surface is not particularly limited as long as the surface can be uniformly coated. The methyl siloxane compound exemplified by the above-mentioned compound is a viscous liquid at room temperature and can be directly applied to the surface of the fluororubber molded product, but it is swellable or non-swellable with respect to the fluororubber in a volatile solvent. It can also be applied in solution.

Further, in the practice of the present invention, the following substances may be added to the peroxide-crosslinked fluororubber in order to impart or modify specific properties. Rubber mechanical properties improver: MT, carbon racks such as FT, dry and wet silica, quartz powder, etc. conductive agent: Ketjen Black (Ketchen ^TM
EC), acetylene blacks, carbon fiber,
Conductive metal coating powder, conductive inorganic and ceramic powder, metal whisker powder, etc. Antistatic agent: Various antistatic agents, surfactants Anti-wear agent: Mica powder, etc. Workability improver: Thermoplastic fluororubber (DAIEL ^TM
Thermoplastics), low molecular weight liquid fluororubber (Dayer ^TM G-101) and fluorosilicone oil and fluorosilicone rubber, fluoro oil compatibility improver, heat resistance additive: silicone oil and reactive silicone oil, silicone resin, silicone Coupling agent Dielectric property control agent: Ceramics such as barium titanate, strontium titanate and organic high dielectric materials High thermal conductivity imparting agent: Metal powder, ceramic powder and various metal oxide powders Heat resistance improver: MgO, Ca ( OH) ₂ , metal oxides and hydroxides such as PbO, organic amine compounds, and others: PFA (tetrafluoroethylene-perfluorovinyl ether copolymer resin), FEP (tetrafluoroethylene-hexafluoropropylene copolymer resin) ),
Tetrafluoroethylene oligomers and reactive perfluoroalkylating agents, and perfluoroalkyl compounds, fluoroether compounds, fluoroalkyl vinyl ether compounds, etc.

The primary vulcanization conditions and the secondary vulcanization (post cure) conditions of the fluororubber composition in the method of the present invention can be appropriately changed. The standard oven heating conditions are 180 ° C. × 4 hours, but 250 ° C. × 24 hours does not cause any problems. Further, the primary vulcanization and secondary vulcanization can be performed in vacuum or in an inert gas such as carbon dioxide gas, helium gas, argon gas or nitrogen gas. Radiation can also be used in primary and / or secondary vulcanization. If desired, the crosslinked rubber may be subjected to UV irradiation or fluorine gas treatment.

Hereinafter, the present invention will be described in more detail with reference to comparative examples and examples, but these examples are only intended to facilitate understanding of the present invention and limit the scope of the present invention. Not a thing.

[ Comparative Example ] Peroxide cross-linking fluororubber (Daiel ^MT G-801, Daikin Chemical Industries) 10
MT carbon black 20 parts by weight 0 parts by weight, triallyl isocyanurate (tike ^TM, manufactured by Nippon Kasei Chemical) 4.0 parts by weight, 2,5-dimethyl-2,5-di -t- butyl peroxy hexane (PERHEXA ^TM 2・ 5B, NOF) 1.
5 parts by weight were sufficiently kneaded with a two-roll machine for rubber, and a sheet having a thickness of 1.5 mm was prepared from the obtained compound by a calender machine. Next, an aluminum core (core metal) having a diameter of 59.0 mm was washed and degreased with 1,1,1-trichloroethane, and Chemlok 60 was used as an adhesive on the roll surface.
7 (Hugson Chemical Co.) primer was applied, and after air-drying for 2 hours, the above-mentioned sheet was wound and heated and pressed at 160 ° C. for 20 minutes in a roll forming die to obtain a rubber roll having a diameter (outer diameter) of 62 mm. . This rubber roll is secondarily heated at 200 ° C. for 4 hours, and after cooling, has an outer diameter of
The surface was ground and finished to mm.

[ Examples ] A finished rubber roll was produced in the same procedure as in Comparative Example except that 3.0 parts by weight of various methylsiloxane compounds were additionally added to the rubber compound shown in Comparative Example. Type and blending amount of methylsiloxane compound Example No. Methylsiloxane compound blending amount (parts by weight) 1 X-22-174D 3.0 (unsaturated group-containing type) 2 LS-8700 3.0 (halogen atom-containing type) 3 LS-8630 3.0 (hydrogen atom-containing type) 4 X-22-174D 1.5 LS-8700 1.5 5 X-22-174D 1.5 LS-8630 1.5 6 LS-8700 1.5 LS -8630 1.5 7 X-22-174D 1.0 LS-8700 1.0 LS-8630 1.0

[0018] The roll and roll of Examples 1 to 7 of the Performance Test Comparative Example Comparative tests have been carried out in performance. In the test, each roll was mounted on an oil fuse type Canon electrostatic dry copying machine NP-7550 as a heat and pressure fixing roll, and A-4 side through 50 sheets /
The actual life was evaluated by measuring the number of copies until the roll surface contamination by the toner, and hence the copy surface contamination, exceeded a certain limit. The results are as shown in the table below.

Example Number Comparative Example Example 1 2 3 Final life 12.3 192 163 176 ( × 10 ³ sheets) Example (continued ) 4 5 6 7 172 153 161 169

[0020]

As shown in the above table, according to the present invention, the final life of the hot-pressing fixing roll of the dry electrostatic copying machine can be remarkably (orderly) extended.

Claims (5)

[Claims] 1. A peroxide-crosslinked fluororubber is reacted with at least one of a group having an ethylenically unsaturated bond bonded to a silicon atom as a reactive group, a methylsiloxane compound containing a halogen atom and / or a hydrogen atom. To improve the affinity of peroxide-crosslinked fluororubber with silicone oil. 2. A peroxide-crosslinked fluororubber is blended with at least one of a group having an ethylenically unsaturated bond as a reactive group, a methylsiloxane compound containing a halogen atom and / or a hydrogen atom. the method of. 3. The surface of a peroxide-crosslinked fluororubber molded article is contacted with at least one of a group having a silicon atom-bonded ethylenically unsaturated bond as a reactive group, a halogen atom and / or a methylsiloxane compound containing a hydrogen atom. The method according to claim 1, wherein the reaction is carried out. 4. A roll having a rigid core and a non-adhesive coating layer, wherein the non-adhesive coating layer has a group having an ethylenically unsaturated bond bonded to a silicon atom as a reactive group, a halogen atom and / or a hydrogen atom. A roll comprising a peroxide-crosslinked fluororubber vulcanizate in which at least the surface affinity for silicone oil is improved by reacting at least one methylsiloxane compound containing 5. The roll according to claim 4, which is a hot-press fixing roll or a backup roll of a dry electrostatic copying machine.