JPH049174B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for surface treatment of vulcanized fluororubber molded articles. More specifically, the present invention relates to a method for surface treatment of a vulcanized fluororubber molded article to reduce surface tackiness and coefficient of friction. [Prior Art] As a method of reducing the surface frictional resistance of vulcanized rubber molded products, surface treatment with tetrafluoroethylene resin has conventionally been carried out, that is, coating with an aqueous dispersion of this resin or coating with a thin film of this resin. However, with the former method, only a thin coating layer can be formed, resulting in deterioration of the surface properties after long-term use, and with the latter method, the adhesion is unstable. However, it has disadvantages such as high cost. [Problems to be solved by the invention] Vulcanized fluororubber molded products have good heat resistance, chemical resistance,
Due to its excellent hot water resistance, it is used in the automobile industry, hydraulic industry, general machinery industry, aircraft industry, etc. in the form of sealants such as oil seals, packings, and gaskets, hoses, and sheets. . However, in recent years, there has been an increasing demand for reducing the surface friction coefficient of rubber materials from the standpoint of energy conservation and noise prevention. Further, the valve function (opening/closing function) of a rubber valve seat may be inhibited due to its surface adhesiveness, which is considered a problem from a safety standpoint. In this way, the importance of making the surface of vulcanized fluorocarbon rubber molded products non-adhesive and with a low coefficient of friction is becoming increasingly important, and if these problems can be solved, the usefulness of these molded products will be further enhanced. Become. The present inventors have conducted various studies on methods for reducing the tackiness and friction coefficient of the surface of molded products without substantially impairing the desirable properties inherent in vulcanized fluorocarbon rubber. It has been found that this problem can be effectively solved by hardening and altering the surface and turning it into a resin. [Means for Solving the Problems] and [Operation] Therefore, the present invention relates to a method for surface treatment of a vulcanized fluorocarbon rubber molded product, and the surface treatment involves treating the surface of the vulcanized fluorocarbon rubber product with an amine or This is done by treatment with an amine salt. The fluororubber that is surface-treated as a vulcanized product is mainly a copolymer of vinylidene fluoride, such as hexafluoropropene, 1,1,
1,2,3-pentafluoropropene, tetrafluoroethylene, trifluoroethylene, 1,2
- Copolymers with difluoroethylene, dichlorodifluoroethylene, chlorotrifluoroethylene, hexafluorobutene, fluorinated vinyl ethers, perfluoroacrylic acid esters, etc. Preferred examples of these copolymers include vinylidene fluoride-hexafluoropropene copolymer, especially a copolymer of about 80:20 mol% thereof, vinylidene fluoride-hexafluoropropene-1,
1,1,2,3-pentafluoropropene ternary copolymers, especially around 80:18:2 mol% copolymers, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene ternary copolymers, etc. Can be mentioned. These vinylidene fluoride copolymers cause a dehydrofluorination reaction under the action of amines, causing the surface of the vulcanized molded product to lose its rubber elasticity and turn into a resin, thereby making it non-adhesive. and achieve a low coefficient of friction. The vulcanized product to be surface treated may be a fluoro rubber unit or a rubber blend containing at least about 5% by weight of fluoro rubber, such as NBR, SBR, acrylic rubber, EPDM, etc. used as. Of course, the following components forming a vulcanization system may be blended as necessary in the fluoro rubber or its blend to be vulcanized and molded. Divalent metal oxide or hydroxide: at least one type of magnesium oxide, calcium oxide, zinc oxide, lead oxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, etc., about 1 to 1 per 100 parts by weight of fluororubber They are used in an amount of 20 parts by weight, preferably about 5 to 10 parts by weight, and act as vulcanization accelerators or anti-aging agents. Polyamine derivatives or polyols: polyamine derivatives such as hexamethylene diamine carbamate, methylene biscyclohexyl carbamate, or 2,2-bis(4-hydroxyphenyl) perfluoropropane, hydroquinone, 4,4-dihydroxydiphenylmethane,
At least one polyol, such as 4,4'-dihydroxyphenyl sulfone, is generally used in a proportion of about 0.5 to 5 parts by weight per 100 parts of fluororubber, and these act as vulcanizing agents. Ammonium or phosphonium compounds: triethylhexadecyl ammonium chloride, triethylbenzylammonium bromide,
1-Butyl-1,4-diazabicyclo[2,2,
2] At least one of ammonium compounds such as octanium chloride or phosphonium compounds such as triphenylbenzylphosphonium chloride, trioctylbenzylphosphonium chloride, and triethylbenzylphosphonium chloride in a proportion of about 0.1 to 3 parts by weight per 100 parts by weight of fluororubber. These act as vulcanization accelerators. In addition, as a vulcanization accelerator, a tertiary phosphine or a tertiary amine and an epoxy compound can also be used together. Other compounding agents: Fillers such as MT carbon black, SRF-carbon black, FEF-carbon black, process oil, processing aids such as dioctyl phthalate, Ibotaro, etc. are appropriately compounded. Each of the components forming the vulcanization system is added and the molded product of fluororubber or a blend thereof is subjected to pressure vulcanization at a predetermined vulcanization temperature and then surface-treated with an amine or an amine salt. These amines used for surface treatment are 1
Arbitrary materials such as class to tertiary aliphatic mono- or polyamines, polyalkylene polyamine condensates, aromatic polyamines, cyclic amines, etc. can be used, and some of them are shown by general formulas or specific compound names. , as follows. (1) Monoalkylamine, dialkylamine, trialkylamine (2) R ₁ R ₂ N-(CH ₂ -) _o NR ₃ R ₄ R ₁ to _{R 4} : Hydrogen atom or alkyl group n: Integer of 2 or more ( 3) R ₁ R ₂ N-(CH ₂ -) _l NH-(CH ₂ -) _n NR ₃ R ₄ R ₁ to _{R 4} : Hydrogen atom or alkyl group m, l: 2 or 6 (4) Triethylenetetramine Tetramine, such as
Pentamine (5) _H2N -R- _NH2R such as tetraethylenepentamine:

【formula】

【formula】

【formula】

【formula】

[Formula] R': -0- -S- -CH ₂ -

〔Effect of the invention〕

According to the method of the present invention, the surface of the vulcanized molded product can be modified without substantially impairing the desirable characteristics inherent in fluorocarbon rubber, that is, the surface hardness can be increased to make it non-adhesive, and the surface friction coefficient can be improved. Therefore, the surface-treated vulcanized fluorocarbon rubber molded product can be effectively used in the various applications mentioned above. [Example] Next, the present invention will be explained with reference to an example. Manufacture of vulcanized fluoro rubber molded products For Compound A or B having the compounding recipe (parts by weight) shown in Table 1 below, the Press vulcanization and 200°C (formulation A) or 230°C (formulation B)
Each was oven-cured for 24 hours at 100
A vulcanized sheet A or B measuring 200 x 2 mm was molded.

[Table] Example 1 The vulcanized sheet A was cut into strips of 10 x 50 x 2 mm, and the test pieces were placed in ethylenediamine at 20°C.
After being immersed in water for 5 minutes, it was taken out and washed with water. Example 2 The test piece of Example 1 was immersed in a 5% by weight methanol solution of 1,8-diazabicyclo[5,4,0]-undec-7-ene at 20°C for 1 minute, and then immersed at 100°C.
and dried for 10 minutes. Example 3 The test piece of Example 1 was immersed in a 5% by weight methanol solution of 4,4-methylene dianiline at 20°C for 3 minutes, and then dried at 150°C for 10 minutes. Example 4 The test piece of Example 1 was immersed in a 10% by weight solution of diethylhexadecylamine in methanol at 40°C for 2 minutes, and then dried at 100°C for 10 minutes. Example 5 The test piece of Example 1 was immersed in a 5% by weight acetone solution of 1,8-diazabicyclo[5,4,0]-undec-7-ene at 20°C for 20 seconds, and then air-dried. Example 6 The vulcanized sheet B was cut into strips of 10 x 50 x 2 mm, and the test pieces were soaked in triethylenetetramine.
It was immersed in a 10% by weight methanol solution at 20°C for 1 minute, then taken out, washed with water, and immediately dried in an oven at 100°C for 10 minutes. The hardness and friction coefficient of the vulcanized sheet surface before and after the amine treatment were measured for the test pieces of each of the above examples. The results obtained are shown in Table 2 below.

【table】

Claims (1)

[Claims] 1. A method for surface treatment of a vulcanized fluororubber molded article, which comprises treating the surface of the vulcanized fluororubber molded article with an amine or an amine salt.