JP2668693B2 - Non-adhesive fluororubber and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-adhesive fluororubber and a method for producing the same, and more particularly, to a fluororubber with improved non-adhesion and a method for producing the same.

(Prior Art of the Invention) Fluororubber is widely used as a fuel valve of an internal combustion engine such as an automobile engine because of its excellent oil resistance.

Such a valve 1 is movable in the axial direction by the action of, for example, an electromagnet 2 or a spring, and makes contact with a valve seat 4 opened in a fluid passage 3 to release the fluid passage 2. It functions to control the amount of fluid flowing in the inside or to perform on-off operation.

Such a valve 1 comprises, for example, a valve shaft 11 made of metal and a valve body 12 provided at the end thereof. Since the valve body 12 is required to have oil resistance and abrasion resistance, fluorine rubber is used. It is used.

When the fluid is controlled using the valve 1 having such a structure, the valve seat 4 and the valve element 12 repeat contact and release countless times. When the valve body 12 is used for a long time in this way, the valve body 12 becomes sticky, the contact portion A between the valve seat 4 and the valve body 12 sticks, and it becomes difficult for the valve 1 to separate,
When it got worse, there was a situation where they could stick and stay apart.

In order to eliminate such disadvantages, a method has been developed in which a surface of the valve body 12 is surface-treated with an amine or an amic acid salt after attaching a valve body 12 made of fluoro rubber to the valve shaft 11 (patented). Published Application No. 81437 (1986)).

According to such a method, the detackification of the fluororubber is improved about three times as compared with the case where the conventional surface treatment is not performed, and the detackification is excellent. However, even when such an amine treatment is performed, the non-adhesiveness cannot be said to be sufficient, and a better non-adhesive fluororubber is required at present.

(Summary of the Invention) The present invention has been made in view of the above points, and it is an object of the present invention to provide a fluororubber having good non-adhesiveness and a method for producing the same, as compared with the related art. It is an object of the present invention to provide a fluororubber exhibiting a synergistically superior effect by detackification and further surface treatment, and a method for producing the same.

Therefore, the non-adhesive fluororubber according to the present invention comprises a compound of the following general formula 5 per 100 parts by weight of fluororubber.
It is characterized in that a surface-treated layer treated with an amine or an amine salt is provided on a vulcanized fluororubber layer into which about 30 parts by weight have been kneaded.

RCONH (CH ₂ ) _n NHCOR ′ (where 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 carbon number having 8 to 20 carbon atoms)
(The alkyl group of 20 and n represents a positive integer of 1 to 8.) In addition, the method for producing a non-adhesive fluororubber according to the present invention employs a compound of the following general formula of 5 to 100 parts by weight of a fluororubber. After at least primary vulcanization of the fluororubber composition kneaded with 30 parts by weight, a surface treatment is carried out with an amine or an amine salt, and if vulcanization is not sufficient, secondary vulcanization is further performed.

RCONH (CH ₂ ) _n NHCOR ′ (where 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 carbon number having 8 to 20 carbon atoms)
20 alkyl groups, and n represents a positive integer of 1 to 8) As a result of intensive studies on detackification of fluororubber, the present inventors added a predetermined amount of a predetermined acid bisamide or alkylurea compound. As a result, it was found that the non-adhesiveness of the fluororubber was improved 100 times or more, and the present invention was achieved.

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

According to the present invention, a compound of the following general formula is added to the fluororubber.

RCONH (CH ₂ ) _n NHCOR ′ (where 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 carbon number having 8 to 20 carbon atoms)
20 alkyl group, n in 1-8 positive an integer) the general formula, but wherein R and R ₁ is an alkyl group having 8 to 20 carbon atoms, from the carbon number of the R and R ₁ 8 If it is small, the melting point will be too low and handling will be difficult.
If it exceeds 20, the viscosity becomes too large and kneading becomes difficult.

n is a positive integer of 1 to 8, but if it is larger than 8, the anti-adhesion effect may not be sufficient.

R ′ is R ₁ or —NHR ₁ , wherein R ₁ is the same or different from the aforementioned R and represents an alkyl group having 8 to 20 carbon atoms.

Specific examples of such compounds include, for example, C ₁₁ H ₂₃
CONH (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 acid H ₃₇ such as bisamides and C ₁₇ H
It can be at _{35 NHCONH (CH 2) NHCONHC 17} H one or more such alkyl ureas, such as _35.

The addition amount of this compound is 5 to 30 parts by weight based on 100 parts by weight of the fluorine rubber. If the amount is less than 5 parts by weight, sufficient detackification may not be achieved, while if it exceeds 30 parts by weight, there may be a disadvantage that various physical properties are reduced.

The fluororubber used in the present invention is not basically limited. Various fluororubbers, such as binary and ternary, can be used. Specific examples include hexafluoropropene, 1,1,1,2,3-pentafluoropropene, tetrafluoroethylene, trifluoroethylene, 1,2-difluoroethylene, dichlorodifluoroethylene, chlorotrifluoroethylene,
Copolymers such as hexafluorobutene, fluorinated vinyl ethers, and perfluoroacrylate can be given.

Such a fluororubber composition of the present invention further comprises a vulcanizing agent, a vulcanization accelerator and an antioxidant. Obviously, appropriate amounts of fillers, processing aids and the like can be added.

In the present invention, the fluororubber composition as described above,
After primary vulcanization or complete vulcanization to obtain a predetermined molded product shape, the surface is treated with amine or amine salt to form a surface treatment layer (in the case of primary vulcanization, the surface treatment layer is After forming, further vulcanization is performed).

As these amines used for the surface treatment, any of primary to tertiary aliphatic mono- or polyamines, polyalkylene polyamine condensates, aromatic polyamines, cyclic amines and the like can be used. Is represented by a general formula or a specific compound name as follows.

(1) monoalkyl amines, dialkyl amines, trialkyl amines _{(2) R 2 R 3 N-} (CH 2) n -NR 4 R 5 R 2 ~R 5: a hydrogen atom or an alkyl group n: 2 or more integer ( _{3) R 2 R 3 N- (} CH 2) l -NH- (CH 2) m -NR 3 R 4 R 1 ~R 4: a hydrogen atom or an alkyl group m, l: 2 or 6 (4) triethylenetetramine (5) H ₂ NR ₆ —NH ₂ R ₆ : Since these aromatic polyamines have a slower rate of surface treatment reaction of molded articles than aliphatic amines, they are preheated to 100 ° C. for heat treatment, or a small amount of an ammonium compound or a phosphonium compound is added. If used, the surface treatment time can be shortened.

(6) 1,8-diazabicyclo (5,4,5) -undec-7-ene 1,5-diazabicyclo (4,3,0) -non-5-ene piperazine hexamethylenetetramine 4-dialkylaminopyridine (7) ) The above-mentioned salts of amines, for example, carbonates, hydrochlorides, ammonium salts, etc.
When heated to a temperature of about 50 to 150 ° C and heat-treated,
The speed of the surface treatment reaction of the molded article can be increased, and the surface treatment time can be shortened.

The surface treatment of the vulcanized fluororubber molded article with these amines can be carried out by any method such as immersion in amines or a solution thereof, for example, methanol, ethanol or acetone solution, brush coating, spraying, coating, immersion in steam. It is carried out at a temperature from room temperature to about 300 ° C., and after completion of the treatment, it is washed with water and dried (at room temperature to 250 ° C. for about 5 to 60 minutes).

 Hereinafter, examples will be described.

Example 1 A ternary fluororubber (Viton) containing an acid bisamide and an alkyl urea compound as shown in Table 1 below
B; Trade name; manufactured by DuPont Co., Ltd.) (including 20 parts by weight of carbon black, 5.5 parts by weight of a crosslinking assistant, and 2 parts by weight of a crosslinking agent peroxide) to produce a fluororubber composition. After vulcanization to form a fluororubber, it was immersed in ethylenediamine at 60 ° C. for 30 minutes and washed with water.

 The tackiness of such a fluororubber was measured.

Using such a fluororubber, the adhesion was tested by an adhesion tester as shown in FIG.

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

The measurement was performed on the sample 5 attached to the plunger 5.
A load of 50 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 evident from this test method, the lower the lifting force, the lower the tackiness. Also, the actual tackiness is
This is a value obtained by subtracting 2 g from the measured value.

 The results are shown in Table 2 below.

As a comparative example, the adhesion of the fluororubber used in the composition was tested.

As is evident from Table 2, the anti-adhesion effect is improved by an average of about 10 times as compared with that of a normal fluorine rubber treated only with an amine.

At the maximum value, the effect was 5 to 13 times, and at the minimum value, the effect was 30 times or more.

Example 2 A fluororubber of the present invention was prepared by changing the amount of the alkyl urea-based compound of Example 4 to the same fluororubber (ternary fluororubber) as in Example 1, and was similarly tackified. It was measured.

In addition, as a comparative example, the tackiness of a fluororubber treated only with an amine as disclosed in JP-A-61-81437 was also measured.

First, a predetermined amount of the compound of Example 4 was added, kneaded, baked on a plunger, and 170 ° C. × 10 minutes (primary vulcanization)
After the primary vulcanization under the conditions described above, the surface of the fluororubber is washed with methanol and washed for 2 minutes with ultrasonic waves to obtain an amine solution (Diak No.1; trade name, DuPont Co., Ltd.)
The sample was immersed in a 20% aqueous solution for 0 to 24 hours, dried and then subjected to secondary vulcanization.

The sample of the comparative example was obtained by baking the same fluororubber on the plunger (primary vulcanization), then methanol and ultrasonic cleaning under the same conditions as above, and then amine solution (Diak No. 1; trade name DuPont Co., Ltd.). After immersing in a 2% aqueous solution for 1 to 24 hours to perform surface treatment, vulcanized one was used as a sample.

 The results are shown in Table 3.

As is clear from Table 3, the amine surface treatment was carried out for 24 hours.
The aged fluoro rubber has an average adhesive strength of 107 g, which is 4 times or more non-adhesive than the adhesive strength (573 g) of the non-adhesive-treated fluoro rubber. However, the average value according to the present invention was 3 g, which was 150 times or more the effect of the non-adhesion-treated fluororubber and 35 times or more the effect of the amine surface treatment.

FIG. 3 shows a graph of the data (average value) of the adhesiveness. In the figure, the black circles indicate the fluorine-treated rubber subjected to the amine surface treatment, and the white circles indicate the fluorine-treated rubber produced from the composition according to the present invention, subjected to the amine treatment.

(Effects of the Invention) As described above, according to the present invention, since an acid bisamide or an alkylurea compound is added and surface treatment is performed with an amine or an amine salt, a remarkably good non-adhesive fluororubber can be obtained. it can. Therefore, there is an advantage that a highly reliable valve body or the like can be manufactured.

[Brief description of the 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 diagram showing the addition amount of the compound of Example 4 according to the present invention and the tackiness. It is a graph which showed the relationship and the amide surface treatment time and adhesiveness (adhesiveness data is an average value). 12 …… Valve.

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Claims (2)

(57) [Claims] 1. A vulcanized fluororubber layer in which 5 to 30 parts by weight of a compound represented by the following general formula is kneaded with respect to 100 parts by weight of a fluororubber, and a surface-treated layer which is surface-treated with an amine or an amine salt is provided. Non-adhesive fluoro rubber characterized by the following. RCONH (CH ₂ ) _n NHCOR ′ (where 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 carbon number having 8 to 20 carbon atoms)
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 of the following general formula with respect to 100 parts by weight of a fluororubber is subjected to at least primary vulcanization, followed by surface treatment with an amine or an amine salt, A method for producing a non-adhesive fluororubber, which further comprises performing secondary vulcanization when vulcanization is not sufficient. RCONH (CH ₂ ) _n NHCOR ′ (where 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 carbon number having 8 to 20 carbon atoms)
20 alkyl groups, and n represents a positive integer of 1 to 8)