JPH07110905B2 - Non-adhesive fluororubber and method for producing the same - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a non-adhesive fluororubber composition, and more specifically,
The present invention relates to a fluororubber composition having improved non-adhesiveness of fluororubber.

(Prior Art of the Invention) Fluorine rubber is often used as a valve element for a fuel system of an internal combustion engine such as an engine of an automobile because of its excellent oil resistance.

Such a valve 1 is axially movable by the action of, for example, an electromagnet 2 or a spring, and is brought into contact with and released from a valve seat 4 provided in a fluid passage 3 so that the fluid passage 2 is formed. It has the function of controlling the amount of fluid flowing through the inside or performing on / off.

Such a valve 1 is composed of, for example, a metal valve shaft 11 and a valve body 12 provided at a tip portion thereof. Since the valve body 12 is required to have oil resistance and abrasion resistance, fluororubber is used. It is used.

When controlling the fluid using the valve 1 having such a structure, the valve seat 4 and the valve body 12 are repeatedly contacted and released a number of times. As described above, when the valve body 12 is used for many years, the valve body 12 becomes sticky, and the valve seat 4 and the valve body 12 become sticky.
Twelve contact parts A adhered to each other, and the valve 1 became difficult to separate, and when it became severe, it adhered and did not separate.

In order to gradually eliminate such drawbacks, a method has been developed in which a valve body 12 made of fluororubber is attached to the valve shaft 11 and then the surface of the valve body 12 is surface-treated with an amine or an amine salt (patent application). Published 1986, No. 81437).

According to such a method, detackification of the fluororubber is improved by about 3 times as compared with the case where conventional surface treatment is not performed, and good detackification is exhibited. However, even when such an amine treatment is carried out, it cannot be said that the non-adhesiveness is sufficient, and under the present circumstances, a further good non-adhesive fluororubber is desired.

(Summary of the Invention) The present invention has been made in view of the above points, and provides a fluororubber having good non-adhesiveness as compared with the conventional one, more specifically, only by surface treatment of the fluororubber. First, it is an object of the present invention to provide a non-adhesive fluororubber having sufficient durability by making the fluororubber itself nonadhesive and providing a surface treatment layer on the fluororubber surface. Another object of the present invention is to easily produce the non-adhesive fluorocarbon rubber.

Therefore, the non-adhesive fluororubber according to the present invention is characterized by containing 5 to 30 parts by weight of the compound of the following general formula per 100 parts by weight of fluororubber, and having a surface treatment layer surface-treated with an organic peroxide on the surface. It is what

RCONH (CH ₂ ) _n NHCOR ′ (wherein R is an alkyl group having 8 to 20 carbon atoms, R ′ is R ₁ or NHR ₁ , and R ₁ is the same or different from the above R 8
20 alkyl groups, n represents a positive integer of 1 to 8) Further, the method for producing a non-adhesive fluororubber according to the present invention,
After vulcanizing a fluororubber composition obtained by kneading 5 to 30 parts by weight of the compound represented by the above general formula with respect to 100 parts by weight of fluororubber, the vulcanized product is treated with 50 to 300 g of an organic peroxide in an organic solvent 11
It is characterized by dipping or applying the treatment liquid in the treatment liquid dissolved therein.

The present inventors have conducted extensive studies on detackification of fluororubber, and by adding a predetermined amount of a predetermined acid bisamide or alkylurea-based compound, the nontackiness of fluororubber is improved 100 times or more. The present invention has been found and has led to the present invention.

(Specific Description of the Invention) The present invention will be described in more detail.

The fluororubber according to the present invention contains a compound represented by the following general formula.

RCONH (CH ₂ ) _n NHCOR ′ (wherein R is an alkyl group having 8 to 20 carbon atoms, R ′ is R ₁ or NHR ₁ , and R ₁ is the same or different from the above R 8;
20 alkyl groups, n represents a positive integer of 1 to 8) In the general formula, R and R ₁ are alkyl groups having 8 to 20 carbon atoms, but R and R ₁ have 8 carbon atoms. If it is too small, the melting point becomes too low, making it difficult to handle.
If it exceeds 20, the viscosity will be too high and the kneading will be difficult.

This is because n is a positive integer of 1 to 8, and if it is larger than 8, the anti-adhesion effect may be insufficient.

R'is R ₁ or -NHR ₁ , and R ₁ represents an alkyl group having 8 to 20 carbon atoms which is the same as or different from R described above.

Specific examples of the above compound include, for example, C ₁₁ H ₂₃ CO
NH (CH ₂ ) ₂ CONHC ₁₁ H ₂₃ , C ₁₇ H ₃₅ CONHCH ₂ CONHC ₁₇ H ₃₅ , C ₁₈ H
₃₇ CONH (CH ₂ ) CONHC ₁₈ H Acid bisamides such as ₃₇ and C ₁₇ H
₃₅ NHCONH (CH ₂ ) NHCONHC ₁₇ H _{35 and the} like can be one or more alkylureas and the like.

The content of this compound is 5 with respect to 100 parts by weight of fluororubber.
~ 30 parts by weight. If it is less than 5 parts by weight, sufficient detackification may not be achieved, while if it exceeds 30 parts by weight, various physical properties may be deteriorated. The fluororubber used in the present invention is basically not limited. Various fluororubbers such as binary and ternary can be used. Hexafluoropropene, 1, 1, 1,
2,3-pentafluoropropene, tetrafluoroethylene, trifluoroethylene, 1,2-difluoroethylene, dichlorodifluoroethylene, chlorotrifluoroethylene, hexafluorobutene, fluorinated vinyl ethers, perfluoroacrylic acid ester, etc. A polymer may be mentioned.

It is obvious that a suitable amount of a vulcanizing agent, a vulcanization accelerator, an antioxidant, a filler, a processing aid and the like can be added to the fluororubber composition of the present invention.

According to the present invention, such a fluororubber surface has a surface-treated layer surface-treated with an organic peroxide.

This surface treatment layer, together with the compound represented by the above general formula added to the fluororubber, has the function of further improving the detackification and at the same time having the function of curing the fluororubber surface, and therefore the durability of the fluororubber is improved. It has the effect of improving the sex.
In the present invention, this surface layer is provided in order to maintain the durability of fluororubber.

Such a surface-treated layer is treated with an organic peroxide, and examples of the organic peroxide include benzoyl peroxide, 2.5 dimethyl-2.5 di (t-butylperoxy) hexane, dicumyl peroxide. , 2.2
-Bis (t-butylperoxy) octane, n-butyl-4.4-bis (t-butylperoxy) valerate, t
-Butyl peroxybenzoate.

By treating with such an organic peroxide,
A surface treatment layer can be formed on the surface of the fluororubber.

When manufacturing such a fluororubber, by a conventional method,
One or more compounds of the above general formula are mixed into the unvulcanized fluororubber and kneaded. The fluororubber composition produced in this manner is molded into a predetermined shape and is heated and pressed to perform primary vulcanization.

Next, the fluororubber is treated with a benzene solution of an organic peroxide.

The benzene solution of the organic peroxide is preferably 50 to 300 g.
A concentration of / l is good. If it is less than 50 g / l, the surface treatment effect may not be sufficient, while if it exceeds 300 g / l, the rubber deteriorates.

A surface layer is formed on the surface of the fluororubber by a method such as brush coating, spray coating, and exposure to the above benzene solution of organic peroxide.

Particularly, it is preferable to carry out the surface treatment by immersing in a benzene solution of an organic peroxide.

The temperature of the solution may be 60 to 100 ° C. If it is less than 60 ° C, the surface treatment may take too long,
On the other hand, if it exceeds 100 ℃, it will decompose thermally.

The immersion time is preferably 30 minutes or longer. If it is less than 30 minutes, the surface may not be sufficiently treated.

Examples will be described below.

Example 1 A ternary fluororubber blended with an acid amide or an alkylurea as shown in Table 1 below (other than carbon black, 20 parts by weight, a crosslinking aid 5.5 parts by weight, a crosslinking agent {peroxide} 2 Parts by weight), and then immersed in a 20% by weight aqueous solution of organic peroxide P (manufactured by NOF CORPORATION) for 1 hour. At this time, the temperature of the solution was 80 ° C. The tackiness of the fluororubber of the present invention thus produced was measured.

For comparison, except for the compound represented by the general formula, a ternary fluororubber having the same composition was produced (no surface treatment was performed), and the tackiness was measured under the same conditions.

Using such a fluororubber, the tackiness was tested by a tack tester as shown in FIG.

That is, the composition sample 6 is attached to the tip of the nickel-iron alloy plunger 5, the composition sample 6 is placed on the valve seat 7, and the force (g) when the plunger 5 is lifted upward by the push bull gauge 8. Was measured. The weight of the sample 6 and the plunger 5 was 2 g.

The measurement is performed on the sample 5 attached to the plunger 5 by 50
A load of g was applied, the sample was pressed against the valve seat 7, the sample was held at 40 ° C. and a humidity of 80% for 20 hours, and then left at 25 ° C. and a humidity of 65% for 4 hours.

As is clear from this test method, the lower the lifting force, the lower the tackiness. The actual tackiness is a value obtained by subtracting 2 g from the measured value.

The results are shown in Table 2 below.

As is clear from Table 2, it was found that the non-adhesive effect was improved by about 10 times in average value as compared with the usual fluororubber.

The maximum value was 5 to 13 times as effective, and the minimum value was 30 times or more effective.

Example 5 In contrast to the fluororubber (ternary fluororubber), the above-mentioned Example 4
The fluororubber of the present invention was produced by adding 15 parts by weight of the compound of Example 1 and the tackiness was measured in the same manner.

Further, as a comparative example, the tackiness of the fluororubber only subjected to the surface treatment with the amine disclosed above was also measured.

First, 15 parts by weight of the compound of Example 4 was added and kneaded, followed by baking on a plunger and secondary vulcanization under the conditions of 200 ° C. for 8 hours, and then the fluororubber surface was washed with methanol and ultrasonicated. After washing for 2 minutes by the method described above, a sample was prepared by immersing it in an aqueous solution of 20% organic peroxide P for 24 hours for surface treatment.

The samples of the comparative examples were prepared by baking the same fluororubber on a plunger, followed by washing with water, secondary vulcanization under the same conditions as above, and methanol and ultrasonic cleaning under the same conditions, and then using an amine solution (Diak No. 1). Trade name, DuPont Co., Ltd.) 1 in 20% aqueous solution
A sample was soaked for -24 hours for surface treatment. Further, the results when the addition amount of the compound of Example 4 was changed (no surface treatment layer was formed) are also shown for reference.

The results are shown in Table 3.

Table 3 As is clear from Table 3, only amine surface treatment
The average adhesive force of the fluororubber after 24 hours is 107 g, which is four times or more non-adhesive as compared with the adhesive force (473 g) of the non-adhesive-treated fluororubber. However, the average value according to the present invention was 3 g, and the effect was 150 times or more that of the non-adhesive-treated fluororubber and 35 times or more that of the case where only the amine surface treatment was performed.

A graph of the adhesiveness data (average value) is shown in FIG. In the figure, the black circles represent the fluororubber only subjected to the amine surface treatment (horizontal axis represents time), and the white circles represent the fluororubber produced by the present invention (horizontal axis represents parts by weight).

(Effects of the Invention) As described above, according to the present invention, since the compound of the general formula is added and the organic peroxide treatment is carried out, a remarkably good non-adhesive fluororubber can be obtained.
Therefore, there is an advantage that a highly reliable valve body or the like can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a valve mechanism, FIG. 2 is a diagram showing a mechanism for testing tackiness, and FIG. 3 is a relation between the addition amount of a compound of the general formula according to the present invention and tackiness. 3 is a graph showing the amine treatment time and adhesiveness as a comparative example (adhesiveness data is an average value). 12 …… Valve.

Claims (2)

[Claims] 1. A surface treatment layer containing 5 to 30 parts by weight of a compound represented by the following general formula based on 100 parts by weight of fluororubber and having a surface-treated surface treated with an organic peroxide. Adhesive fluororubber. RCONH (CH ₂ ) _n NHCOR ′ (wherein R is an alkyl group having 8 to 20 carbon atoms, R ′ is R ₁ or N HR ₁ , and R ₁ is the same or different from the above R 8;
To 20 alkyl groups, and n represents a positive integer of 1 to 8) 2. A fluororubber composition obtained by kneading 5 to 30 parts by weight of a compound represented by the following formula with 100 parts by weight of fluororubber is vulcanized, and then the vulcanized product is treated with 50 to 50% of organic peroxide. 300g
A method for producing a non-adhesive fluororubber, which comprises immersing or applying the treatment liquid in a treatment liquid prepared by dissolving the above in an organic solvent 11. RCONH (CH ₂ ) _n NHCOR ′ (wherein R is an alkyl group having 8 to 20 carbon atoms, R ′ is R ₁ or N HR ₁ , and R ₁ is the same or different from the above R 8;
To 20 alkyl groups, and n represents a positive integer of 1 to 8.