JPH0137737B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an undercoat composition for fluoro-rubber paints, and more specifically, the present invention relates to an undercoat composition for fluoro-rubber paints, and more specifically, it can be applied to base materials, especially without impairing the excellent properties of fluoro-rubber, such as heat resistance, oil resistance, chemical resistance, and solvent resistance. The present invention relates to an undercoat composition for fluororubber paints for imparting strong adhesion to silicone rubber. Fluoro rubber has poor adhesive properties, so when coating it on the surface of a base material such as metal, rubber, or plastic,
Usually, the surface of the base material is roughened or pretreated by solvent degreasing, and then an undercoat composition is applied, and the fluororubber is coated thereon. As undercoat compositions for fluoro rubber paints, those based on epoxy resins or silane coupling agents are generally 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 fluoro rubber. Fluorine rubber is inert and has poor compatibility with other general rubbers and plastics, making it extremely difficult to achieve practical adhesion, especially when the base material is silicone rubber. be. For example, in an electronic copying machine, the toner image formed on the printing material is finally fused by fixing and back-up rolls, but elastic rolls with a silicone rubber layer are most often used as these rolls. has been done. However, non-tacky fusing and back-up rolls are required for the fusing toner because the fusing toner tends to adhere to these rolls, resulting in blurred printed images. In order to meet such requirements, a non-adhesive elastic roll (Japanese Patent Application Laid-Open No. 58-5770) has been proposed in which a fluorocarbon rubber paint layer containing a fluorocarbon resin is provided on the outer peripheral surface of the roll body. These fixing and back-up rolls are sufficiently satisfactory in terms of non-adhesion with the fused toner, but especially when the base material is silicone rubber, in other words, the fluororesin is attached to the roll body through a silicone rubber layer. Although a fluorine paint layer containing fluorine paint is provided, the adhesion is not sufficient. As a result of studies to eliminate the drawbacks of the above-mentioned conventional methods, the present inventors have developed an undercoat composition for fluoro-rubber paints that has greatly improved the adhesion between silicone rubber and fluoro-rubber as base materials. They discovered this and completed the present invention. The gist of the present invention resides in an undercoat composition for a fluororubber paint for a fixing roll or a backup roll of an electronic copying machine, which comprises at least one kind of acrylic resin. The acrylic resin is a polymer or copolymer of acrylic acid or its ester, or methacrylic acid or its ester. Examples of esters include methyl, ethyl, propyl, butyl, 2-ethylhexyl, and glycidyl esters, and esters with polyhydric alcohols. Copolymers include copolymers with vinyl acetate, vinyl chloride, styrene, etc. Examples include polymers. 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, carbitols, and water. It is. The concentration of the acrylic resin is usually 1 to 90% by weight, preferably 5 to 50% by weight. Furthermore, by incorporating a silane coupling agent or an organic titanate, the undercoat composition of the present invention is also useful for silicone rubbers containing silicone rubber base materials or fillers (eg, white carbon, red iron, etc.). The undercoat composition for fluororubber paints of the present invention is prepared by dissolving an acrylic resin in a liquid carrier or by solution polymerization by a conventional method. The prepared composition is applied to a substrate, especially a silicone rubber surface, by conventional coating methods (eg brushing, dipping, spraying, etc.) and dried. A fluororubber paint is applied and cured on the dried undercoat surface by a conventional method. Next, examples and comparative examples will be shown to specifically explain the present invention. Examples 1 to 4 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 with the following composition (however, the fluororesin dispersion of liquid A was not used in Example 4) was spray-coated on top of the coating, dried at 60°C for 10 minutes, and then cured at 300°C. Then, a fluororubber coating layer with a thickness of about 30 μm was provided on the silicone rubber vulcanized plate. For 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 in the case where no undercoat composition was used (Comparative Example 1) and in the case where conventionally known undercoat compositions for fluororubber paints were used (Comparative Examples 2 and 3). The results are also listed in the table below. Fluoro rubber paint (for 100 parts by weight of the following liquid A,
Blend 3 parts by weight of the following B liquid) A liquid fluororubber ⁽¹⁾ Aqueous dispersion (fluororubber content 60% by weight) ......100 parts by weight Fluororesin ⁽²⁾ Aqueous dispersion (fluororubber) Resin content 50% by weight) ...100 Magnesium oxide ...3 Nonion HS-210 (manufactured by NOF Corporation)
...2〃 Water ...50〃 B liquid γ-Aminopropyltriethoxysilane
...40 〃 8,9-bis(8-aminopropyl)-2,4,
8,10-tetraoxaspiro[5.5]undecane ...20 〃 Water ...40 〃 (Note 1) Vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene elastic copolymer (Note 2) Tetrafluoroethylene/hexafluoro propylene copolymer

[Table] Example 5 After roughening the surface of an aluminum core metal by sandblasting, washing with acetone, and drying,
Wrapped with HTV (heat curing type) silicone rubber,
Vulcanization molding at 170℃ for 15 minutes, then 2 hours at 200℃
Next vulcanization was performed. Next, the surface of the vulcanized silicone rubber was polished to produce a roll. The surface of this roll was spray-coated with Primer D using a spray gun with a nozzle diameter of 1.0 mm at an air pressure of 2 kg/cm ² G, and dried at 60° C. for 10 minutes. Furthermore, the same fluororubber paint as in Example 1 was spray-painted thereon under the same conditions, dried at 60°C for 10 minutes, and then cured at 300°C for 30 minutes. In addition,
The thickness of the undercoat layer was about 10 μm, and the thickness of the fluororubber coating layer was about 30 μm. A dry copying machine equipped with a fixing device incorporating the fixing roll thus obtained was used to pass 300,000 sheets of A4 paper. At this time, the surface temperature of the fixing roll is
The temperature was 160-170℃. After cooling, the fixing roll was removed and the appearance was observed. No abnormalities such as peeling between the silicone rubber layer and the fluorine rubber layer or wrinkles were observed.

Claims (1)

[Claims] 1. Comprising at least one type of acrylic resin,
An undercoat composition for fluoro rubber paints for fixing rolls or backup rolls of electronic copying machines. 2. The composition according to claim 1, wherein at least the surface of the fixing roll or backup roll is made of silicone rubber. 3. The composition according to claim 1, wherein the acrylic resin is an acrylic ester resin. 4. The composition according to claim 1, wherein the fluororubber paint contains a fluororesin.