JPH05140402A - Fluororubber composition - Google Patents

Abstract

PURPOSE:To prepare a fluororubber composition excellent in heat resistance, low-temp. properties, mold release properties, and chemical resistance and having characteristics of silicone rubber. CONSTITUTION:The objective composition comprises 100 pts.wt. fluororubber and 1-50 pts.wt. amino-modified organopolysiloxane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororubber composition having improved low temperature characteristics, surface releasability and the like by adding an amino-modified organopolysiloxane.

[0002]

Fluorine rubber is an elastomer having excellent heat resistance and chemical resistance, but since it is expensive and has poor processability, it has hitherto been blended with other polymers. Fluorinated rubber compositions have been investigated.

However, an industrially useful fluororubber composition has not been obtained yet, and much research has been continued especially on blending with a silicone rubber having excellent heat resistance similar to that of fluororubber, but both have been studied. Is basically incompatible, so that it is difficult to knead, and thus the molded product obtained has phase separation due to phase separation at the time of crosslinking, and practical properties cannot be obtained. Very few successful cases.

As a method for producing a fluororubber composition in which a fluororubber and a silicone rubber are blended, a method of adding an organopolysiloxane to the fluororubber for the purpose of improving workability and releasability (JP-A-3- 2230
No. 8) has been proposed. However, since organopolysiloxane does not have reactivity with fluororubber, it has poor compatibility as described above, and the resulting molded article has a risk of bleeding of the silicone component and change in physical properties over time. Therefore, the amount of the organopolysiloxane compounded is in the range of 1 to 15 parts by weight based on 100 parts by weight of the fluororubber.

Further, a method of fixing the organopolysiloxane to the fluororubber by adding shearing during heating by adding peroxide (JP-A-1-198646).
Issue). In this method, in addition to silicone rubber, a third elastomer, that is, SP of both
It is necessary to add a peroxide-crosslinkable elastomer at an intermediate value of the values. Therefore, considering the heat resistance and the like, the third component is limited and
Since this composition is an amine or polyol cross-linking system, there is a risk that the reaction will proceed at room temperature due to a small amount of water, and there is concern about storage stability.

Further, a method has been proposed in which the cross-linking agent is a modified organopolysiloxane (JP-A-2-173145). In this method, the cross-linking agent bleeds during storage from kneading to molding. Therefore, there are problems that the crosslink density becomes unstable, and that if a large amount of modified organopolysiloxane that acts as a crosslinker is added, the physical properties decrease.

As described above, regarding the blend of the fluororubber and the organopolysiloxane, various proposals have been made to solve the poor compatibility between the two, but the interphase peeling, the kneading workability, the storage stability, the organo stability There are many difficulties in solving all the problems such as bleeding of polysiloxane and obtaining a blend satisfying excellent physical and chemical properties.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a fluororubber composition containing an organopolysiloxane that solves the above problems.

[0009]

Means and Actions for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that 100 parts by weight of a fluororubber contains 1 part of amino-modified organopolysiloxane.
In the case of blending up to 50 parts by weight, the fluororubber and amino groups react with each other to fix the organopolysiloxane to the fluororubber, so that the fluororubber characteristics such as heat resistance, chemical resistance and mechanical characteristics and low temperature characteristics In addition to maintaining the properties of the amino-modified organopolysiloxane, such as mold release property and workability, it becomes easy to blend the fluororubber and the organopolysiloxane, which have poor compatibility and are easy to separate. The inventors have found that the bleeding problem of the silicone component in the molded article obtained from the composition can be solved and a fluororubber composition having stable physical properties can be obtained, and the present invention has been completed.

The present invention will be described in more detail below. The fluororubber composition of the present invention comprises 100 parts by weight of a fluororubber and 1 to 50 parts by weight of an amino-modified organopolysiloxane.

The fluororubber, which is the main material constituting the fluororubber composition of the present invention, is a highly fluorinated elastic copolymer. Specific examples of such fluororubber include vinylidene fluoride. And hexafluoropropene, pentafluoropropene, trifluoroethylene,
Trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether)
And an elastic copolymer with one or more kinds thereof.
Among such elastic copolymers, vinylidene fluoride-hexafluoropropene binary elastic copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropene ternary elastic copolymer and the like are particularly preferably used. Is mentioned.

In the present invention, in order to make the fluororubber composition have good storage stability, it is preferable to use peroxide-based crosslinks rather than amine- or polyol-based crosslinks which are easily affected by moisture. .. Examples of peroxides include dibenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-t-butyl peroxide. Oxyhexane etc. are mentioned.

The amount of these peroxides added is 1 to 20 parts with respect to 100 parts of fluororubber (parts by weight, the same applies hereinafter),
In particular, it is preferably 2 to 10 parts. If it is less than 1 part, the crosslinking will be insufficient, and if it exceeds 20 parts, it will be difficult to knead it with the fluororubber, so that the mechanical strength of the fluororubber composition may decrease.

Further, it is preferable to add a crosslinking aid to the composition of the present invention. Examples of such a crosslinking aid include diallyl ether of glycerin, triallyl phosphoric acid, diallyl adipate, diallyl melamine, triallyl isocyanurate and triallyl cyanurate.
The addition amount of this cross-linking agent is 1-2 for the same reason as the above-mentioned cross-linking agent.
It is preferably 0 part, especially 2 to 10 parts.

Next, the amino-modified organopolysiloxane which is an important component of the present invention may be any one having at least one amino group in one molecule, and the amino group is the first.
Either a primary amine or a secondary amine can be used.

In the above organopolysiloxane, there is no limitation on the organic groups other than the amino group. Specific examples of the other organic group include a methyl group, a propyl group, a vinyl group, a phenyl group, a trifluoropropyl group, an acryl group, a methacryl group, an epoxy group, a methoxy group and an ethoxy group. Of these, a methyl group, a vinyl group, a phenyl group and a trifluoropropyl group are particularly preferable.

The degree of polymerization of the amino-modified organopolysiloxane is preferably 3 or more. If the degree of polymerization is less than 3, the organopolysiloxane will volatilize during or after the kneading with fluororubber, etc., and the amino groups contained will be excessive compared to the siloxane units, and the reaction during kneading will be excessive. Occasionally, workability may deteriorate.

The same applies to the amino group equivalent, and the amino group equivalent is preferably in the range of 200 to 100,000 g / mol, particularly 500 to 50,000 g / mol. If the amino group equivalent is less than 200 g / mol, the reaction during kneading may proceed excessively, resulting in poor workability. If it exceeds 100,000 g / mol, the amino group may not easily react with the fluororubber, and Since the number of reactive groups is small, it may cause separation during blending or phase separation of molded products.

The viscosity of the amino-modified organopolysiloxane is not particularly limited, and any of oil, grease, and raw rubber can be used, but those having a high viscosity are particularly preferable from the viewpoint of workability in the initial stage of kneading. used.

The amount of such amino-modified organopolysiloxane compounded is 1 to 50 parts, preferably 3 to 40 parts, per 100 parts of the fluororubber. If it is less than 1 part, the effect of adding the organopolysiloxane is small,
If it exceeds 50 parts, the mechanical properties of the fluororubber composition will deteriorate and foaming will occur during crosslinking molding.

Further, a filler, an acid acceptor and a plasticizer may be added to the fluororubber composition, if necessary.
Specifically as the filler, silica, carbon black,
Alumina, red iron oxide, clay, calcium carbonate, titanium oxide, polytetrafluoroethylene powder, various conductive fillers, heat radiation fillers and the like can be mentioned. Of these, silica and carbon black are preferable from the viewpoint of reinforcement. Further, these fillers are preferably surface-treated with a silane-based or titanate-based surface treatment agent. In addition, the compounding amount of the filler is 50 with respect to 100 parts of fluororubber.
It is preferably not more than a part.

Specific examples of the acid acceptor include magnesium oxide, calcium oxide, calcium hydroxide, barium stearate, and lead oxide. Of these, magnesium oxide and lead oxide are particularly preferable.

Examples of the plasticizer include fluorinated oils, greases, fatty acid esters, etc., but the addition of the amino-modified organopolysiloxane improves the workability without adding a plasticizer, and is not particularly required. ..

In order to produce the fluororubber composition of the present invention, the above-mentioned components are kneaded, but the kneading is conventionally used because it is preferable to disperse the above-mentioned components in the fluororubber composition sufficiently uniformly. It is preferable to use a two-roll rubber roll, a pressure kneader, a kneader, a Banbury mixer, etc., which is suitable for each compounding condition.

When the fluororubber and the organopolysiloxane are kneaded, slipping is caused by the organopolysiloxane in the initial stage, which hinders the kneading work. However, by adding the filler powder, slippage can be suppressed. Then, kneading becomes easy.

Further, when the viscosity of the fluororubber is lowered by heating, the workability is improved, and in addition, the reaction between the fluororubber and the amino group proceeds to more effectively fix the organopolysiloxane. .. In this case, the heating temperature is preferably 30 to 200 ° C, particularly preferably 50 to 150 ° C. If the heating temperature is lower than 30 ° C., a considerable time is required for the kneading work, and if the heating temperature is higher than 200 ° C., the reaction rapidly progresses and gas generation or amino group reaction is unevenly distributed, which may deteriorate workability. When the heating temperature is 50 to 150 ° C., the reaction between the fluororubber and the amino group proceeds mildly and a good composition can be easily obtained.

The roll workability of the blend of the fluororubber thus obtained and the amino-modified organopolysiloxane is good, and therefore the additives other than the peroxide are added during the kneading of the fluororubber and the amino-modified organopolysiloxane. Although there is no problem even if it is added to the above, since peroxide may be decomposed by heating, it is preferable to add separately after cooling.

[0028]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 4] Vinylidene fluoride-tetrafluoroethylene-as fluororubbers I and II
Hexafluoropropene terpolymer (Dayer G90
2 (manufactured by Daikin), Viton GF (manufactured by DuPont), and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (Perhexa 25B) as a crosslinking agent.
(Manufactured by NOF Corporation)), KF-393, KF-869, KF- which are represented by the following general structural formulas (1) to (4) as amino-modified organopolysiloxanes and have the characteristics shown in Table 1.
864, KF-873 (manufactured by Shin-Etsu Chemical Co., Ltd.), TAIK (manufactured by Nippon Kasei) as a crosslinking aid, and R972 as a filler.
(Made by Nippon Aerosil), Cumag 40 as an acid acceptor
(Manufactured by Kyowa Kagaku) was used.

[0030]

[Chemical 1]

[0031]

[Table 1]

Of the above-mentioned components, fluororubber I or II and amino-modified organopolysiloxane were gradually added to a two-rubber roll having a surface temperature of 60 ° C. in the amounts shown in Table 1 while adding a filler. When kneaded, the rubber composition turned pale yellow as the temperature rose due to mechanical heat generated by kneading.

After cooling the obtained composition, the remaining additives were kneaded and found to have good roll processability. Next, when a sheet having a thickness of 2 mm was molded under the conditions of 170 ° C. for 10 minutes, the mold releasability was good, and a yellowish brown elastic sheet with advanced modification of amino groups was obtained.

The elastic sheet was subjected to secondary crosslinking under the crosslinking conditions of 200 ° C. for 2 hours to prepare samples, and various tests shown in Table 2 were conducted. The results are shown in Table 2. It was found that there was no bleeding of the organopolysiloxane, and there was no interphase separation, which was a good sample.

[Comparative Example 1] A sample was prepared by the same steps as in Examples 1 to 4 except that the amino-modified organopolysiloxane was not added. These physical properties are also shown in Table 2.

[0036]

[Table 2]* 1: Good: 2 × 100 × 125 without using a release agent
mm sheet can be formed. ×: The above sheet cannot be formed without using a release agent. 2: ○: dispersed within 20 minutes Δ: dispersed within about 30 minutes ×: 40 minutes or more required for dispersion

Example 5 A sample was prepared by adding 20 parts of the amino-modified organopolysiloxane in Example 2 and the addition amount of the amino-modified organopolysiloxane was 0 parts (Comparative Example 1) and 10 parts (comparative example 1). With the sample of Example 2), the Gehman torsion tester (manufactured by Kamijima Seisakusho) was used to JIS.
A low temperature twisting test based on K6301 was performed. The results are shown in Table 3. From this measurement result, it can be seen that the low temperature characteristics are improved as the compounding amount of the amino-modified organopolysiloxane is increased.

[0038]

[Table 3]

[Comparative Example 2] In the formulation of Example 2, 5 gamma-aminopropyltriethoxysilane (KBM903, manufactured by Shin-Etsu Chemical Co., Ltd.) having one amino group per silicon atom was used in place of the amino-modified polysiloxane. As a part, the same operation as in Example 2 was performed. Immediately after the amino-modified siloxane was added, heat was generated, the composition turned yellow, the viscosity increased, and the composition adhered to the sample, so that the kneading operation was continued. Has become impossible.

[Comparative Example 3] In the formulation of Comparative Example 1, an amino-modified organopolysiloxane (KF-86 described above) was used.
When 0.5 part of 9) was added, almost no discoloration was observed in the composition, and roll workability was not improved. When this was molded in the same manner as Comparative Example 1, the mold releasability was improved, but the physical properties of the molded product were not significantly different from Comparative Example 1 except that the hardness was slightly increased.

[Comparative Example 4] In the formulation of Example 2, when the amount of the amino-modified organopolysiloxane added was 60 parts, a pale yellow composition having good roll workability was obtained. When it was press-molded with, a large number of large bubbles were generated, and a molded product whose physical properties could not be measured was obtained, and a practical composition could not be obtained.

[0042]

INDUSTRIAL APPLICABILITY According to the present invention, a fluororubber composition having excellent heat resistance, low temperature resistance, releasability and chemical resistance and having the characteristics of silicone rubber can be obtained. Since the product is an elastomer composition, it can be used in a wide variety of applications.

Claims (2)

[Claims] 1. A fluororubber composition comprising 100 parts by weight of fluororubber and 1 to 50 parts by weight of an amino-modified organopolysiloxane. 2. The composition according to claim 1, which contains a peroxide crosslinking agent as the crosslinking agent.