JPS6067542A - Primer composition for fluororubber coating - Google Patents

Abstract

PURPOSE:To provide titled composition capable of affording fluororubber coating with firm bonding to base material esp. silicone rubber without impairing the excellent characteristics inherent in the fluororubber, containing at least one sort of epoxy-modified silicone resin. CONSTITUTION:An epoxy-modified silicone resin derived from the condensation between the hydroxyl group of epoxy resin and the silanol group of silicone resin is incorporated in a liquid carrier such as toluene, xylene, acetone, methyl cellosolve so as to be 1-90 (pref. 5-60)wt% in concentration, thats obtaining the objective composition. This composition is coated (by brushing, dipping, spray coating, etc.) on the surface of e.g. silicone rubber, being dried followed by applying to the coated surface a fluororesin-contg. fluororubber coating. Said composition may be modified with fatty acid, also being preferably incorporated with drying promotor such as lead, manganese, cobalt and/or curing agent such as organic amine, acid anhydride, phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an undercoat composition for fluororubber paints, and more specifically, the present invention relates to an undercoat composition for fluororubber paints, and more specifically, an undercoat composition that can be used without impairing the outstanding properties of fluororubber such as heat resistance, oil resistance, chemical resistance, and solvent resistance. , relates to an undercoat composition for fluororubber paints for imparting strong adhesion to substrates, particularly silicone rubber.

Fluororubber has poor adhesive properties, so when coating it on the surface of a base material such as metal, rubber, or plastic, the base material surface is usually roughened or pretreated with solvent degreasing, and then an undercoat composition is applied. , on which fluororubber is coated.

As undercoat compositions for fluororubber paints, those based on general epoxy resins or silane coupling agents are used. These generally exhibit good adhesion when the base material is metal, but do not exhibit a satisfactory adhesive effect when the base material is a rubber other than fluororubber.

Fluororubber is inert and has poor compatibility with common rubbers and plastics, making it extremely difficult to achieve practical adhesion, especially when the base material is silicone rubber. . For example, in an electronic copying machine, the toner image formed on the printing material is finally fused by a fixing and backup roll, but elastic rolls with a silicone rubber layer are most often used as these rolls. ing. However, non-tacky fusing and back-up rolls are required for fusing toner because fusing toner tends to adhere to these rolls, resulting in blurred printed images.

In order to meet such requirements, a non-adhesive elastic roll (VF Publication No. 58-5770) has been proposed in which a fluororubber paint layer containing a fluororesin is provided on the outer peripheral surface of the roll body. These fixing and backup rolls are quite satisfactory in terms of non-adhesion with the fused toner, but this is especially true when the base material is silicone rubber, that is, when the fluororesin is applied to the roll body through a silicone rubber layer. Although a fluororubber coating layer containing

As a result of conducting studies to eliminate the drawbacks of the above-mentioned conventional methods, the present inventors have discovered an undercoat composition for fluororubber paints that has greatly improved the adhesion between silicone rubber and fluororubber as base materials. , we have completed the present invention.

The gist of the present invention resides in an undercoat composition for fluororubber paints comprising at least one epoxy-modified silicone resin.

Epoxy-modified silicone resins are obtained by a condensation reaction between hydroxyl groups of epoxy resins and silanol groups of silicone resins. Furthermore, the obtained epoxy-modified silicone resin may be modified with a fatty acid.

The undercoat composition of the present invention contains lead, manganese, cobalt, zinc, which is a drying accelerator for epoxy-modified silicone resin,
Organic salts such as calcium, and/or organic amines as curing agents, acid anhydrides, 7-ether resins, amino resins,
It is preferable to add polyamide or the like.

Commonly used liquid carriers include aromatic solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, cellosolve solvents such as methyl cellosolve and butyl cellosolve, lower alcohols, calpitols, and water. be.

The concentration of the epoxy-modified silicone resin is usually 1 to 90% by weight, preferably 5 to 60% by weight.

The undercoat composition for fluororubber paints of the present invention is prepared by adding an epoxy-modified silicone resin to a liquid carrier by a conventional method.

The prepared composition is applied to a substrate, especially a silicone rubber surface, by conventional coating methods (eg, 3-brushing, dipping, spraying, etc.) and dried.

On the dried undercoat surface, a fluororubber paint is applied and cured by a conventional method.

Next, examples and comparative examples will be shown to specifically explain the present invention.

Examples 1 to 2 and Comparative Examples 1 to 3 The undercoat composition shown in the following table was brushed onto a silicone rubber vulcanized plate and dried at 60'C for 5 minutes. Furthermore, a fluororubber paint having the following composition (however, the fluororesin paint of liquid A was not used in Example 2) was spray-coated on top of the coating, dried at 60°C for 10 minutes, and then cured at 300°C to coat the silicone. A fluororubber coating layer with a thickness of about 30 μm was provided on a rubber vulcanized plate.

Regarding the sample thus obtained, the peel strength between the silicone rubber vulcanized plate and the fluororubber coating layer was measured using a universal tensile tester. The results are shown in the table below.

For comparison, the same tests were conducted for the case where no undercoat composition was used (Comparative Example 1) and the case where a conventionally known undercoat composition for fluororubber paint was used (Comparative Examples 2 and 3). The results are also listed in the table below.

Fluororubber paint (for 100 parts by weight of the following liquid A, the following B)
3 parts by weight of liquid) Liquid A fluororubber 1) Aqueous disvergitane (fluororubber content 60% by weight) ......100 parts by weight fluororesin 2) Aqueous dispersion (fluororesin content 50% by weight) ・・・・・・・・・100 〃 Magnesium oxide ・・・・・・・・・ 3 //Nonion H8-210 (manufactured by NOF Corporation) ・・・・・・・・・2 〃 Water ・・・・・・・・・ 50 〃 B liquid γ-aminopropyltriethoxysilane ・・・・・・・・・
・・ 40 〃 8.9-bis(8-7minoprovir)-2,4,8,1
0-tetraoxaspiro(5,5]undecane...
・・・・・・ 20 〃Water ・・・・・・・・・ 40
〃 Note 1) Vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene elastic copolymer 2) Tetrafluoroethylene/hexafluoropropylene copolymer 7- Note 1) Epoxy-modified silicone resin (manufactured by Toray Silicone Co., Ltd.) 2) Epoxy-modified silicone resin curing agent (manufactured by Toray Silicone Co., Ltd.) 3) Silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd.) 4) Epoxy resin (manufactured by Shell Chemical Co., Ltd.) 5) Polyamine-based curing agent (Mitsubishi Manufactured by Yuka Co., Ltd.) Patent applicant Daikin Industries Co., Ltd. Agent Patent attorney Aoyou Ao (2 others) 8-

Claims (3)

[Claims] (1) An undercoat composition for a fluororubber paint comprising at least one epoxy-modified silicone resin. (2) A composition according to claim 1 for use in a silicone rubber base material. (3) The composition according to claim 1, wherein the fluororubber paint contains a fluororesin.