JPH07157584A - Production of fomable fluororubber composition - Google Patents

Abstract

PURPOSE:To provide a method for producing a fomable fluororubber composition, not losing effect of a blowing agent even by heat generation when blending the fluororubber with various components, having excellent storage stability, providing a high-quality spongy fluororubber by foaming treatment. CONSTITUTION:This method for producing a fomable fluororubber composition is mixing (1) a composition A comprising a polyol cross-linking-based fluororubber and one to three additives selected from a polyol cross-linking agent, a catalyst, an acid trapping agent and a blowing agent with (2) a composition B comprising a polyol cross-linking-based fluororubber and three to one additives which are not selected in the component A, and kneading them.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a foamable fluororubber composition, in particular, the foaming agent does not expire due to heat generated during compounding and kneading. The present invention relates to a method for producing an expandable fluororubber composition that gives rubber.

[0002]

2. Description of the Related Art Since fluororubber is an elastomer excellent in heat resistance, chemical resistance and mechanical strength, it is industrially used in a wide range of fields mainly in the automobile and machine industries. However, the fluorinated rubber composition obtained by blending the uncured fluororubber polymer with various components generally has a large green strength at around room temperature. Therefore, when these various components are blended and mixed, heat is generated and partial crosslinking proceeds. However, this fluororubber composition has a disadvantage that a composition having excellent storage stability cannot be obtained.

[0003]

Further, regarding this fluororubber composition, when a foaming agent is added to obtain a sponge fluororubber, this is blended and mixed with various components by, for example, a two-roll mill. When kneading, heat is generated at 90 to 120 ° C., so that scorch is generated in the heat history for several minutes or the foaming agent is deactivated, and therefore, there is a drawback that a good quality sponge-like fluororubber cannot be obtained. It is considered that this is because when the foaming agent is exposed to a high temperature fluororubber composition in which various components are kneaded in a high concentration state, the foaming agent is decomposed together with partial cross-linking of the fluororubber. Especially in the above cases, even if cooling water is passed through a kneading device such as a two-roll machine, it is not a fundamental solution, and this is a problem in mass production and industrialization of the fluororubber composition.

[0004]

The present invention relates to a method for producing a foamable fluororubber composition which solves the above disadvantages and problems, which is 1) a polyol crosslinking fluoroelastomer and a polyol crosslinking agent, Composition A consisting of 1 to 3 kinds of additives selected from 4 kinds of catalyst, acid acceptor and foaming agent, 2) polyol crosslinked raw rubber and composition A
Compositions A and B of composition B consisting of 3 to 1 type of additive not selected in (wherein the polyol cross-linking agent, the catalyst, the acid acceptor and the foaming agent are either composition A or B). Included) and kneading these.

That is, the present inventors have blended various components,
As a result of various studies to develop a method for producing a foamable fluororubber composition in which the foaming agent does not expire even when kneaded, as a result, a polyol crosslinking fluoroelastomer, a polyol crosslinking agent, a catalyst, an acid acceptor, and a foaming agent are simultaneously prepared. Without kneading, a polyol cross-linking agent, a catalyst, an acid acceptor and a foaming agent are separately mixed and kneaded, and the two compositions are kneaded. It was found that scorch does not occur even if a heat history of 5 to 15 minutes is applied, and the foaming agent does not become ineffective. Therefore, according to this, if this material is subjected to foaming treatment later, the desired sponge-like fluororubber is obtained. The present invention has been completed after confirming that it is possible. This will be described in more detail below.

[0006]

The present invention relates to a method for producing an expandable fluororubber composition, which comprises, as described above, 1) a polyol crosslinking fluoroelastomer and a polyol crosslinking agent, a catalyst, an acid acceptor and a foaming agent. Composition A, which is composed of 1 to 3 kinds of additives selected, 2) Composition B, which is composed of a polyol-crosslinked fluorine-containing raw rubber and 3 to 1 kinds of additives not selected in the composition A. A and B (however, a polyol cross-linking agent, a catalyst, an acid-accepting agent, and a foaming agent are contained in any of the compositions A and B) are mixed, and these are kneaded. According to the method, the foaming agent does not expire even if various components are kneaded with the fluororubber and heat is generated, which provides an advantage that a foamable fluororubber composition can be easily obtained.

The composition A constituting the expandable fluororubber composition of the present invention comprises 1 to 3 kinds selected from 4 kinds of polyol crosslinkable fluorine raw rubber and polyol crosslinker, catalyst, acid acceptor and foaming agent. It consists of additives,
This polyol-crosslinkable fluorine raw rubber is a highly fluorinated elastic copolymer, specifically, an elastic copolymer of vinylidene fluoride and hexafluoropropene, tetrafluoroethylene, pentafluoropropene, trifluoroethylene, Examples thereof include elastic copolymers with one or more kinds of vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether) and the like. Among these, vinylidene fluoride-hexafluoropropene diene The original elastic copolymer and vinylidene fluoride-tetrafluoroethylene-hexafluoropropene terpolymer are preferred. It is also possible to use liquid fluororubber containing iodine or bromine and having an average molecular weight of about 500 to 20,000 and liquefied. Commercially available liquid fluororubber is G101 [trade name of Daikin Co., Ltd.], Viton L
M [Showa Denko / Dupont brand name] and the like.

The polyol cross-linking agent acts as a cross-linking agent for the polyol cross-linkable fluorine raw rubber and is a polyhydroxy aromatic compound or a fluorine-containing aliphatic compound. Specifically, bisphenol A, bisphenol B, Bisphenol AF, 1,3,5-trihydroxybenzene, hydroxyresorcin, 2-t-butylhydroquinone, 2-methylresorcin, 1,5-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,
2,2-bis (4-hydroxyphenyl) butane, 3,
3,5-Trichlorobisphenol A, 4,4-dihydroxydiphenyl, CF2 (CF2CH2OH) 2, HOCH2 (CF2) 4OCF (C
F3) CH2OH, CF2 (CFHCF2CH2OH) 2, (CF2) 3 (CFHCF2CH2OH) 2
Among these, especially bisphenol A,
Bisphenol B, bisphenol AF, 2-t-butylhydroquinone and the like are preferable.

However, the polyol cross-linking agent may be a silylated polyol, and as the silylated polyol, those represented by the following formulas are particularly preferable, and these are used alone or in combination of two or more kinds. Can be used.

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4] (In the formula, R5 is the same or different monovalent organic group having 1 to 10 carbon atoms or hydrogen atom, and examples thereof include a methyl group, an ethyl group, a vinyl group, a methoxy group, an ethoxy group, and the like. (R6 is F or H, and F is particularly preferable.)

Specific examples of such silylated polyols include the following.

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

If the amount of the polyol cross-linking agent is less than 0.1 parts by weight based on 100 parts by weight of the total polyol cross-linking fluororubber of the above-mentioned compositions A and B, the mechanical physical properties of the cross-linked fluororubber will be high. If the amount exceeds 10 parts by weight, the physical properties are not particularly improved, and bleeding may occur. Therefore, the range is 0.1 to 10 parts by weight, particularly 0.5 to 5 parts by weight. Good to do.

Next, this catalyst acts as a crosslinking accelerator, which has the following general formula:

[Chemical 11] (Wherein R7, R8, R9, and R10 are monovalent hydrocarbon groups having 1 to 20 carbon atoms, X is P or N, and Y is a halogen atom), and the formula [R112 P = N = PR123] + Y- (wherein R11 and R12 are monovalent hydrocarbon groups having 1 to 20 carbon atoms,
Examples of the onium salt include benzyltriphenylphosphonium chloride or bromide, and the iminium salt includes bisbenzyldiphenylphosphiniminium. The amount of this catalyst added may be in the range of 0.1 to 10 parts by weight, preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the total polyol-crosslinking fluoroelastomer of the compositions A and B described above. .

Examples of the acid acceptor include metal compounds, such as magnesium oxide, calcium oxide, lead oxide, calcium hydroxide and barium stearate, which may be used alone or in combination of two or more. Can be used in the composition A
And B total polyol crosslinkable fluorine raw rubber 10
It may be in the range of 1 to 20 parts by weight with respect to 0 parts by weight.

The blowing agent may be a known one, and as the organic blowing agent, N, N-dimethyl-N, N-dinitrosoterephthalamide, dinitrosopentamethylenetetramine and azobis are used as the organic blowing agent from the viewpoint of bubble stability. Examples thereof include isobutyronitrile, azodicarbonamide, p-toluenesulfonyl hydrazide, P, P-oxybisbenzenesulphonyl hydrazide, p-toluenesulfonyl semicarbazide, and trihydrazinotriazine. In addition, it is optional to add a urea-based, organic acid-based, or metal salt-based auxiliary agent to the organic foaming agent in order to adjust its decomposition temperature. The organic foaming agent may be used. If the amount of the organic foaming agent is less than 1 part by weight per 100 parts by weight of the total polyol-crosslinked fluororubber of the compositions A and B, the amount of the foaming is not stable and the amount is 30 parts by weight or more. Since crosslinking inhibition occurs in the fluororubber composition, it is necessary to set it in the range of 1 to 30 parts by weight, preferably 3 to 20 parts by weight.

On the other hand, the composition B constituting the expandable fluororubber composition of the present invention comprises a polyol crosslinking fluoroelastomer and a polyol crosslinking agent, a catalyst, an acid acceptor and a foaming agent not selected in the above composition A. The polyol cross-linking fluororubber may be the same as or different from the polyol cross-linking fluoro-raw rubber of the composition A, which is composed of 3 to 1 type of additives. Of the agents, catalysts, acid acceptors, and foaming agents, those not included in the composition A are all included. In addition, as this preferable combination combination, it is preferable that the polyol cross-linking agent and the foaming agent are separately provided. Therefore, in particular, the composition A is obtained by adding the polyol cross-linking agent, the catalyst and the acid acceptor to the polyol cross-linking fluoroelastomer. Composition B is preferably composed of a polyol crosslinkable fluororubber and a foaming agent.

If desired, known fillers and colorants may be added to the fluororubber composition. Examples of the filler include silica, carbon black, alumina,
Examples include red iron oxide, clay, calcium carbonate, titanium oxide, polytetrafluoroethylene powder, various conductive fillers, various heat-releasing fillers, and among these, silica and carbon black are preferable from the viewpoint of reinforcement, and especially M
Although T carbon black is preferred, these powders may be treated with a silane-based or titanate-based surface treatment agent in order to disperse, reinforce or improve wettability.

In the production of the expandable fluororubber composition according to the present invention, the composition A and the composition B are blended and kneaded. The composition A is obtained by adding the polyol crosslinkable fluorocarbon rubber to the polyol crosslinker and the catalyst. In order to completely disperse these additives in the raw rubber composition, 1 to 3 kinds of additives selected from 4 kinds of acid acceptor and foaming agent and MT carbon black are added if necessary, Book roll,
It may be kneaded using a kneader, a pressure kneader, a Banbury mixer, etc. In this case, the temperature rises to near 100 ° C due to heat generation, and this involves the four components of polyol crosslinker, catalyst, acid acceptor and foaming agent. Since it is not mixed at the same time, decomposition of scorch and foaming agent does not occur. However, it is preferable to pass cooling water through the two rolls, the pressure kneader and the like. Further, this composition B was not selected in the above polyol crosslinkable fluororubber and the composition A 3 to 1
The same kind of additives as those used for the composition A may be blended and kneaded.

In order to obtain the desired expandable fluororubber composition, the composition A and the composition B may be kneaded while being cooled with cooling water or the like using a two-roll machine or the like. Although the heat generation depends on the green strength and kneading amount of the composition, it is preferably suppressed to 120 ° C. or lower in any case, whereby scorch generation and foaming agent deactivation can be prevented.

[0019]

EXAMPLES Next, production examples of silylated polyol crosslinking agents used in the present invention, examples of the present invention, and comparative examples will be given. Production Example (Production of Silylated Polyol Crosslinking Agent) Hexamethyldisilazane.LS-7 as a silylating agent,
150 [Shin-Etsu Chemical Co., Ltd. trade name] 16.1 g (0.1 mol) dissolved in 10 g toluene, powdered bisphenol AF [Riedel-dehaen reagent] 33.6 g (0.1
Mol) was added and mixed and stirred. At room temperature, the reaction started, gas was generated along with the smell of ammonia, and bisphenol AF was dissolved.

This is the following reaction formula

[Chemical 12] It is presumed that hexamethyldisilazane was decomposed to generate ammonia and the OH group of bisphenol AF was silylated as shown in FIG.
After the completion of the dissolution of the above, the liquid was depressurized and the toluene and volatile components were removed, and the liquid was removed with an infrared spectrophotometer FT / TR-5,00.
0 When analyzed by [trade name of JASCO Corporation],
No absorption of OH groups was observed in the chart of infrared absorption spectrum, confirming that bisphenol AF was silylated.

Example 1 Polyol cross-linking fluororubber (vinylidene fluoride-hexafluoropropene binary copolymer) FC2260
[Sumitomo 3M product name] 10kg, Carbon Black Sanimarks MT [Harbor product name] 600g,
When 50 g of benzyltriphenylphosphonium chloride as a catalyst, 600 g of magnesium oxide and 600 g of calcium hydroxide as an acid acceptor, and 550 g of the silylated polyol cross-linking agent produced in the Production Example were uniformly kneaded while cooling with a two-roll mill, The heat generated by the roll was 90 ° C,
This produced composition IA.

Then, a polyol crosslinkable fluororubber
(Vinylidene fluoride-hexafluoropropane binary copolymer) -FC2145 [Sumitomo 3M Co., Ltd. product name] 10 kg azodicarbonamide-based foaming agent as a foaming agent, Celmic CAP250 [Sankyo Kasei Co., Ltd. product] Name]
When 2 kg was added and kneading was carried out while cooling with a two-roll roll, the heat generation of the roll was 100 ° C., and thus composition IB was produced.

Next, 10 kg of this composition IA and composition IB
When 10 kg and 2 kg were uniformly kneaded while cooling with two rolls, the heat generation of the rolls at this time was 95 ° C., but since a foamable fluororubber composition was obtained by this, the storage stability and The dispensed preform was left in a drier at 150 ° C. for 60 minutes, and the sponge properties after curing were examined. The results shown in Table 1 below were obtained.

Comparative Example 1 The components other than the foaming agent and Celmic CAP250 (described above) in Example 1 were uniformly kneaded while cooling with a two-roll mill, and then the foaming agent and Celmic CAP250 were mixed.
(Previously) When 2 kg was added and kneaded, the scorch started 5 minutes after the addition of the foaming agent despite cooling, and the kneading became impossible, resulting in a partially foamed non-uniform rubber-like cured product. It is had. The heat of the roll at this time is 1
It was 00 ° C.

Comparative Example 2 When components other than benzyltriphenylphosphonium chloride as a catalyst in Example 1 were kneaded uniformly while cooling the two rolls, the heat generated at this time was 1
It was 00 ° C. Then, when trying to knead benzyltriphenylphosphonium chloride as a catalyst uniformly with two rolls, a scorch was observed in a part after about 15 minutes, and it became a non-uniform fluororubber cured product with many lumps. It was

Example 2 Polyol cross-linked fluororubber FC2145 (previously mentioned) 8 kg and liquid fluororubber G101 [trade name / binary copolymer manufactured by Daikin Industries, Ltd.] 2 kg, foaming agent / cell microphone CAP25
When 0 kg (described above) of 1.8 kg was uniformly kneaded while being cooled by two rolls, the heat generated by the rolls was 80 ° C., and thus composition IIB was produced. Then 10 kg of this composition IIB
And 10 kg of the composition IA produced in Example 1 were uniformly kneaded while being cooled by two rolls, and the heat generation of the rolls was 90.
However, since a foamable fluororubber composition was obtained, the storage stability of this composition and the sponge properties after curing were examined, and the results shown in Table 1 below were obtained. Was given.

Example 3 Polyol cross-linking fluorine raw rubber FC2260 (previously mentioned) 10 kg
Bisphenol AF600 as a polyol crosslinking agent
g, benzyltriphenylphosphonium chloride 50g as a catalyst, magnesium oxide 600g as an acid acceptor,
When 1.2 kg of calcium hydroxide and 1 kg of carbon black Thermax MT (described above) as a filler were added and kneaded uniformly with two rolls, the heat generation of the rolls was 95 ° C. IIIA was produced.

Then, a polyol cross-linking fluorine raw rubber
8 kg of FC2145 (previous), 2 kg of liquid fluororubber G101 (previous), and foaming agent, Celmic CAP250 (previous) 2 kg
Was added, and the mixture was uniformly kneaded while being cooled with two rolls. The heat generated by the rolls at this time was 80 ° C., and thereby composition IIIB was produced.

Next, 10 kg of this composition III A and composition II
When 10 kg of IB was uniformly kneaded while cooling with two rolls, the heat generation of the roll was 90 ° C., but since a foamable fluororubber composition was obtained by this, the storage stability of this composition and When the physical properties of the sponge after curing were examined, the results shown in Table 1 below were obtained.

Example 4 Polyol cross-linking fluorine raw rubber FC2260 (previously mentioned) 15 kg
Bisphenol AF (900 g) and Celmic CAP250 (previously described) (3 kg) were evenly kneaded with a two-roll mill to produce a composition IVA (roll heat generation 95 ° C.). Then, 12 kg of polyol crosslinked fluorocarbon rubber FC2260 (described above) was uniformly kneaded with 75 g of benzyltriphenylphosphonium chloride, 900 g of magnesium oxide and 1.8 kg of calcium hydroxide by two rolls to produce a composition IVB (roll heat generation). 95 ° C).
Next, the composition IVA and the composition IVB were kneaded while being cooled with a two-roll, and the storage stability of this composition and the physical properties of the sponge after curing were examined, and the results shown in Table 1 were obtained. was gotten.

[0031]

[Table 1]

[0032]

Industrial Applicability The present invention relates to a method for producing a foamable fluororubber composition, which comprises, as described above, 1) a polyol crosslinkable fluorine raw rubber and a polyol crosslinker, a catalyst, an acid acceptor and a foaming agent. 1-3 selected from types
Composition A consisting of two kinds of additives, composition B consisting of polyol crosslinkable fluoroelastomer and three to one kinds of additives not selected in the composition A. , Characterized by kneading these,
According to this, the foaming agent does not expire even when heat is generated when each composition is kneaded, and therefore, an advantage that a foamable fluororubber composition can be easily obtained is provided.

Claims (1)

[Claims] 1. A composition A comprising a 1) polyol cross-linking fluorocarbon rubber and 1 to 3 types of additives selected from 4 types of polyol cross-linking agent, catalyst, acid acceptor and foaming agent, 2) polyol cross-linking. Compositions A and B of composition B comprising a fluorine-based raw rubber and 3 to 1 type of additive not selected in composition A (however, the polyol crosslinking agent, the catalyst, the acid acceptor and the foaming agent are the compositions. Included in either A or B)
And a kneading method for producing a foamable fluororubber composition.