JPH0323104B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION The present invention relates to novel vulcanized compositions of fluoroelastomers. In more detail,
The present invention provides a fluoroelastomer vulcanizate that has particularly low compression set and excellent heat resistance, oil resistance, and chemical resistance, and also has excellent vulcanization properties, processing stability, storage stability, etc. The present invention relates to vulcanized compositions. Prior Art Advanced fluoroelastomer vulcanizates have excellent heat resistance, oil resistance, chemical resistance, etc., and are therefore used in various industrial fields, such as automobiles, ships, aircraft, hydraulics, general machinery industry, and pollution control. It is widely used in related fields as sealing materials such as O-rings and gaskets, diaphragms, hoses, rolls, and sheet materials. When a fluorinated elastomer vulcanizate is used for such purposes, it is necessary that the vulcanizate has particularly low compression set. Traditionally, vulcanization of fluoroelastomers is carried out using aliphatic diamines or organic peroxides as crosslinking agents. However, this method has poor scorch resistance (processing stability, storage stability), and the resulting vulcanizate has a large compression set, making it not necessarily suitable for the above-mentioned uses. . Therefore, it has been desired to develop a fluoroelastomer vulcanizate composition that has both sufficient curing speed and scorch resistance, and can provide a vulcanizate with a small compression set. Therefore, in order to improve these drawbacks, a method of crosslinking using an aromatic polyol has recently been put into practical use. In this vulcanization system, vulcanization accelerators such as quaternary phosphonium salts (Japanese Patent Publication No. 51-11138), quaternary ammonium salts (Japanese Patent Publication No. 52-38072), 8-alkyl (or aralkyl )-1,8-diaza-bicyclo[5.4.0]-7-undecene quaternary ammonium salt (Japanese Patent Publication No. 52-8863), aminophosphinic acid derivatives (Japanese Patent Publication No. 17222-1987), bis (Triarylphosphine) iminium salt (European Patent Publication No. 120,462-A) and the like are known. However, even when such a vulcanization system is used, the compression set of the vulcanizate at high temperatures is not at a fully satisfactory level. There is a problem in that when the amount of vulcanization accelerator is increased in order to shorten the compression set, the compression set becomes extremely poor. As a solution, quaternary phosphonium salts or quaternary ammonium salts are used as vulcanization accelerators,
Furthermore, a composition using phosphorus triorganoate or sulfur diorgano oxide as an adjuvant has been proposed (Japanese Patent Publication No. 38461/1983). However, in this composition, when an adjuvant that accelerates curing is used, the physical properties of the vulcanizate, especially the compression set, deteriorate, and an adjuvant that does not deteriorate the physical properties is used. When used, the curing process is only slightly accelerated, and the composition cannot be said to fully solve the above-mentioned problems. Problems to be Solved by the Invention The purpose of the present invention is to solve these problems,
Provides a vulcanizate with low compression set and excellent heat resistance, oil resistance, chemical resistance, etc. similar to conventional fluoroelastomer vulcanizates, and excellent vulcanization properties such as easy curing. It is an object of the present invention to provide a fluoroelastomer vulcanized composition which has the following properties and also has excellent processing stability and storage stability. Means for Solving the Problems As a result of extensive research, the present inventors have found that iminium salts are used as vulcanization accelerators, specific sulfone compounds are used as vulcanization accelerators, and polyol compounds and divalent metals are used as crosslinking agents. It has been discovered that a composition prepared by blending these oxides and hydroxides into a specific fluoroelastomer copolymer can meet the above objective, and based on this knowledge, the present invention has been completed. Ivy. That is, the present invention provides (A) an elastomer copolymer having a vinylidene fluoride unit and at least one other fluorine-containing monomer unit, (B) an iminium salt-based vulcanization accelerator, and (C) a polyol. System crosslinking agent, (D) general formula (R ¹ and R ² in the formula are each an unsubstituted or neutral group-substituted alkyl group or aryl group having 1 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and these are the same and (E) a divalent metal oxide or a divalent metal hydroxide or a mixture thereof. A sulfur composition is provided. The fluoroelastomer copolymer used as component (A) in the vulcanized composition of the present invention has a vinylidene fluoride unit and at least one other fluorine-containing monomer unit, and the at least one Examples of other fluorine-containing monomer units include hexafluoropropene 1,2,3,3,3-
Pentafluoropropene, 3,3,3-trifluoropropene, tetrafluoroethylene, trifluoroethylene, 1,2-difluoroethylene,
Examples include dichlorodifluoroethylene, chlorotrifluoroethylene, hexafluorobutene, fluorinated vinyl ethers, fluorinated alkyl vinyl ethers, perfluoroacrylates, and especially hexafluoropropene, pentafluoropropene, and tetrafluoroethylene. is important. Further, as specific examples of the fluoroelastomer copolymer of component (A), vinylidene fluoride-hexafluoropropene copolymer, vinylidene fluoride-hexafluoropropene-1,2,3,3,3-pentafluoropropene copolymers, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene copolymers, and the like. Vulcanization of these copolymers is performed by converting the double bonds produced by a chemical dehydrofluorination reaction of hydrogen in molecules such as vinylidene fluoride units and pentafluoropropene units in the copolymers into crosslinking points. It is done as. In the vulcanization composition of the present invention, the iminium salt vulcanization accelerator as component (B) is usually of the general formula [In the formula, R ¹ , R ² , R ³ are the same or different unsubstituted or neutral group-substituted alkyl groups having 1 to 20 carbon atoms, unsubstituted or neutral group-substituted alkyl groups having 7 to 20 carbon atoms
is an aralkyl group, or an aryl group unsubstituted or substituted with a neutral group, and X is a halogen ion,
Hydroxide ion, sulfate ion, thiosulfate ion, nitrate ion, nitrite ion, formate ion, acetate ion, cyano ion, thiocyano ion, tetraphenylborate ion, tetrafluoroborate ion, 2-mercaptopenzothiazole ion, etc. It is an anion of [(C ₆ H ₅ ) ₃ P=N=P(C ₆ H ₅ ) ₃ ] (X has the same meaning as above), such as bis(trimethylphosphine) iminium chloride, bis(tributylphosphine) iminium chloride, bis(trioctylphosphine) iminium chloride , bis(dodecyldimethylphosphine)iminium chloride, bis(tetradecyldimethylphosphine)iminium chloride, bis(hexadecyldimethylphosphine(iminium chloride), bis[tri(4-methylphenyl)phosphine]i) minium chloride, bis[tri(4-methoxyphenyl)phosphine)]iminium chloride, bis[tri(4-fluorophenyl)phosphine]iminium chloride, bis[tri(4-chlorophenyl)phosphine]iminium Chloride, bis[tri(4-bromophenyl)phosphine]iminium chloride, bis(methyldiphenylphosphine)iminium tetraphenylborate, bis(methyldiphenylphosphine)iminium chloride, bis(butyldiphenyl) enylphosphine) iminium bromide, bis(dodecyl phenylphosphine) iminium bromide, bis(tetradecyl diphenylphosphine)
iminium chloride, bis(hexadecyldiphenylphosphine) iminium chloride,
Bis(cyclohexyldiphenylphosphine) iminium chloride, bis(benzyldiphenylphosphine) iminium chloride, bis(benzyldiphenylphosphine) iminium acetate, bis[benzyldi(4-methoxyphenyl)phosphine ] Iminium chloride,
Bis[benzyldi(4-chlorophenyl)phosphine]iminium chloride, bis[benzyldi(4-chlorophenyl)phosphine]iminium chloride, bis[benzyldi(4-bromophenyl)phosphine]iminium chloride, bis[benzyldi(4-bromophenyl)phosphine]iminium chloride, bis[benzyldi(4-chlorophenyl)phosphine]iminium chloride, -cyanophenyl)phosphine] iminium chloride, bis[benzyldi(4-dimethylaminophenyl)phosphine] iminium chloride, bis[4-methylbenzyldi(4-methylphenyl)phosphine]
iminium chloride, bis(2,4-dimethylbenzyldiphenylphosphine) iminium chloride, bis(4-methoxybenzyldiphenylphosphine) iminium chloride, bis(4-fluorobenzyldiphenylphosphine) Examples include iminium chloride, bis(4-chlorobenzyldiphenylphosphine) iminium chloride, and bis(4-bromobenzyldiphenylphosphine) iminium chloride. Among these, particularly preferable iminium salts are:
Bis(benzyldiphenylphosphine) iminium chloride. These iminium salts are described, for example, in Journal of Organic Chemistry, Vol. 32, 3461.
~3466 pages (1967)”, “Inorganic
Inorganic Syntheses, Volume 15, 85~
87 pages (1974), Acta Chemica Scandinavica, A31
Volume, pp. 645-650 (1977),
Chemishe Berichte, vol. 110, 3528~
3535 pages (1977), Anorganische und Allgemeine Hemie (Anorganishe
und Allgemeine Chemie), Vol. 492, pp. 122-134 (1982). As the polyol crosslinking agent used as component (C) in the vulcanized composition of the present invention, at least one compound selected from polyhydroxy aromatic compounds and fluorine-containing polyhydroxy aliphatic compounds is preferably mentioned. . Examples of polyhydroxy aromatic compounds include bisphenol A, bisphenol AF, resorcinol, 1,3,5-trihydroxybenzene, 1,7-dihydroxynaphthalene,
2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxystilbene, 2,
6-dihydroxyanthracene, hydroquinone, tecol, 2,2-bis(4-hydroxyphenyl)butane, 4,4-bis(4-hydroxyphenyl)valeric acid, 2,2-bis(4-hydroxyphenyl) tetrafluorodichloropropane,
4,4'-dihydroxydiphenyl sulfone, 4,
4'-dihydroxydiphenylketone, tri(4-
hydroxyphenyl)methane, 3,3',5,5'-
Tetrachlorobisphenol A, 3, 3', 5,
5'-Tetrabromobisphenol A and the like are examples of fluorine-containing polyhydroxy aliphatic compounds.
CF ₂ (CF ₂ CH ₂ OH) ₂ , HOCH ₂ (CF ₂ ) ₄ OCF (CF ₃ )
CH ₂ OH, HOCH ₂ (CF ₂ ) ₂ OCF (CF ₃ ) CH ₂ OH,
CF ₂ (CFHCF ₂ CH ₂ OH) ₂ , (CF ₂ ) ₃ (CF ₂ CH ₂ OH) ₂ ,
(CF ₂ ) ₃ (CFHCF ₂ CH ₂ OH) ₂ , (CF ₂ ) ₅
Examples include (CF ₂ CH ₂ OH) ₂ , (CF ₂ ) ₅ (CFHCF ₂ CH ₂ OH) ₂ . Particularly preferred polyhydroxy compounds among these are bisphenol AF and hydroquinone, which may also be alkali metal salts or alkaline earth metal salts. These compounds may be used alone or in combination of two or more. The sulfone-based sulfur accelerator used as component (D) of the vulcanized composition of the present invention has the general formula (R ¹ and R ² in the formula have the same meanings as above)
It is a sulfone compound represented by , which contains a sulfur atom bonded to two oxygen atoms, and two organic groups directly bonded to the sulfur atom through a single C--S bond. Such sulfone compounds include:
For example, (CH ₃ ) ₂ SO ₂ , (C ₂ H ₅ ) ₂ SO ₂ , (n-
C ₃ H ₇ ) ₂ SO ₂ , (n-C ₄ H ₉ ) ₂ SO ₂ , (n-
C ₆ H ₁₃ ) ₂ SO ₂ , (cyclo-C ₆ H ₁₁ ) ₂ SO ₂ , (n-
C ₇ H ₁₅ ) ₂ SO ₂ , (n-C ₈ H ₁₇ ) ₂ SO ₂ , (n-
C ₁₀ H ₂₁ ) ₂ SO ₂ , (n-C ₁₈ H ₃₇ ) ₂ SO ₂ ,

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Examples include [Formula]. Among these, R ¹ and R ² in the general formula ()
However, sulfone compounds each being an alkyl group having 1 to 20 carbon atoms and substituted with an unsubstituted or neutral group are preferred. Further, these sulfone compounds may be used alone or in combination of two or more. The divalent metal oxide, dimetal hydroxide, or mixture thereof used as component (E) in the vulcanized composition of the present invention is, for example, an oxide or hydroxide of a divalent metal such as magnesium, zinc, calcium, or lead. or mixtures thereof, which may contain from 1 to 70% by weight of metal salts of weak acids.
Metal salts of this weak acid include, for example, stearates, benzoates, carbonates, oxalates of barium, sodium, potassium, lead, calcium, etc.
Examples include phosphites. Regarding the blending ratio of each of the above-mentioned components in the vulcanized composition of the present invention, based on 100 parts by weight of component (A),
Component (B) is 0.05 to 2.0 parts by weight, preferably 0.1 to 1.5 parts by weight, and component (C) is 0.1 to 10.0 parts by weight, preferably 0.5 parts by weight.
~5.0 parts by weight, component (D) in the range of 0.05 to 10.0 parts by weight, preferably 0.1 to 5.0 parts by weight, and component (E) in the range of 0.5 to 30.0 parts by weight, preferably 1.0 to 20.0 parts by weight. In the vulcanized composition of the present invention, if necessary,
Other ingredients, such as fillers and reinforcing agents such as carbon black, silica, clay, diatomaceous earth, and talc, plasticizers, and coloring agents, may be added as long as they do not depart from the gist of the present invention. , one or more conventionally known vulcanizing agents and accelerators may be blended. The vulcanized composition thus obtained is vulcanized according to a conventional method. This vulcanization method includes, for example, a method in which the mixture is kneaded in a roll-type rubber mill or a Banbury mixer, placed in a mold and pressurized for primary vulcanization, and then secondary vulcanization. Generally, the conditions for primary vulcanization are a temperature of 100 to 210°C, a time of 3 to 180 minutes, and a pressure of 20 to 100 kg/ ^cm2 , and the conditions for secondary vulcanization are a temperature of 150 to 300°C and a time of 0 to 30 minutes. A time range is used. In addition, other vulcanization methods include a method of preforming such as injection or extrusion, and then vulcanizing it;
Alternatively, a solution or dispersion is prepared using one or more of ketones such as methyl ethyl ketone, acetone, and cyclohexanone, and ethers such as methyl ethyl ether, diethyl ether, dioxane, and tetrahydrofuran. It is also possible to use a method of coating and vulcanizing the surface of a film, sheet, plate, tube, pipe, tank, large container, or other molded product. Effects of the invention The fluoroelastomer vulcanized composition of the present invention has
It has excellent vulcanization properties such as being easily hardened, as well as excellent processing stability and storage stability.Furthermore, the vulcanizate obtained from this product has a particularly low compression set. Furthermore, it has excellent heat resistance, oil resistance, and chemical resistance, similar to fluoroelastomer vulcanizates obtained using conventionally known vulcanizing agents. As described above, the vulcanized composition of the present invention has extremely high industrial value. Examples Next, the present invention will be explained in more detail with reference to Examples. Example 1 Mooney viscosity (121℃, using ML type rotor)
103 parts by weight of vinylidene fluoride-hexafluoropropene-tetrafluoroethylene (67:13:20 mol%) fluoroelastomer copolymer was wound around two rolls, and 30 parts by weight of MT carbon black and hydroxylated After kneading 6 parts by weight of calcium, 3 parts by weight of magnesium oxide (Kiyowa Mag 150), 2 parts by weight of bisphenol AF, 0.45 parts by weight of bis(benzyldiphenylphosphine) iminium chloride and 1.0 parts by weight of dimethylsulfone, the mixture was left overnight. It was left to mature. After that, knead it again, put it into a mold, and heat it up.
Press vulcanization was performed at 177℃ for 5 minutes, and the sheet and O
Each was molded into a ring. Next, it was taken out from the mold and heated in an air circulation furnace at a temperature of 232°C for 24 hours to complete the secondary vulcanization. Note that Shore hardness (JIS-A), modulus, tensile strength, and elongation were all measured according to JISK6301. In addition, the compression set is determined by compressing an O-ring (inner diameter 23.7 mm, thickness 3.5 mm) by 25%.
Placed in the oven at 200℃ for 72 hours, ASTM D-396-61
The vulcanization test was carried out using a disc rheometer under the conditions of 177°C, frequency of 3 cpm, and amplitude of 3°. The vulcanization characteristics, mechanical properties, and compression set of the molded product thus obtained are shown in the table. Example 2 Example 1 except that vinylidene fluoride-hexafluoropropene (78:22 mol%) with a Mooney viscosity (121°C, using an ML rotor) of 36 was used as the fluoroelastomer copolymer. A vulcanized composition was prepared in exactly the same manner as in Example 1, and various tests were conducted. The results are shown in the table. Example 3 A vulcanized composition was prepared in the same manner as in Example 2, except that 3.0 parts by weight of dibutylsulfone was used instead of 1.0 parts by weight of dimethylsulfone, and various tests were conducted. The results are shown in the table. Example 4 In Example 1, the vulcanized composition was prepared using 1.0 parts by weight of bis(4-fluorophenyl)sulfone instead of 1.0 parts by weight of dimethylsulfone, and the press vulcanization time was changed to 6 minutes. A molded article was prepared in the same manner as in Example 1, and various tests were conducted. The results are shown in the table. Example 5 Example 1 was repeated except that 1.0 parts by weight of bis(4-chlorophenyl)sulfone was used instead of 1.0 parts by weight of dimethylsulfone to prepare the vulcanized composition, and the press vulcanization time was changed to 7 minutes. A molded article was prepared in the same manner as in Example 1, and various tests were conducted.
The results are shown in the table. Example 6 In Example 2, instead of 0.45 parts by weight of bis(benzyldiphenylphosphine) iminium chloride, bis(methyldiphenylphosphine)
A vulcanized composition was prepared in the same manner as in Example 1, except that 0.34 parts by weight of iminium chloride was used, and various tests were conducted. The results are shown in the table. Example 7 Example 2 except that 0.43 parts by weight of bis(triphenylphosphine) iminium chloride was used instead of 0.45 parts by weight of bis(benzyldiphenylphosphine) iminium chloride. Prepare a vulcanized composition in the same manner as
Various tests were conducted. The results are shown in the table. Comparative Example 1 A molded article was prepared in the same manner as in Example 1, except that a vulcanized composition was prepared without using dimethylsulfone, and the press vulcanization time was changed to 10 minutes, and various tests were carried out. I went. The results are shown in the table. Comparative Example 2 A molded article was prepared in the same manner as in Example 2, except that the vulcanized composition was prepared without using dimethyl sulfone and the press vulcanization time was 10 minutes, and various tests were carried out. I went. The results are shown in the table. Comparative Example 3 A molded article was prepared in the same manner as in Example 6, except that the vulcanized composition was prepared without using dimethylsulfone, and the press vulcanization time was changed to 10 minutes, and various tests were carried out. I went. The results are shown in the table. Comparative Example 4 A molded article was prepared in the same manner as in Example 7, except that the vulcanized composition was prepared without using dimethylsulfone, and the press vulcanization time was changed to 10 minutes, and various tests were carried out. I went. The results are shown in the table. Comparative Example 5 The vulcanized composition was prepared in the same manner as in Example 1, except that 0.45 parts by weight of bis(benzyldiphenylphosphine) iminium chloride in Example 1 was changed to 0.70 parts by weight, and dimethylsulfone was not used. We prepared products and conducted various tests. The results are shown in the table. Comparative Example 6 In Example 7, 0.43 parts by weight of bis(tripheninylphosphine) iminium chloride was
A vulcanized composition was prepared in the same manner as in Example 7, except that the amount was changed to 0.57 parts by weight and dimethylsulfone was not used, and various tests were conducted. The results are shown in the table below.

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Claims (1)

[Scope of Claims] 1 (A) an elastomer copolymer having a vinylidene fluoride unit and at least one other fluorine-containing monomer unit, (B) an iminium salt-based vulcanization accelerator, (C)
Polyol crosslinking agent, (D) General formula (R ¹ and R ² in the formula are each an unsubstituted or neutral group-substituted alkyl group or aryl group having 1 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and these are the same and (E) a divalent metal oxide or a divalent metal hydroxide or a mixture thereof. Sulfur composition. 2 R ¹ and R ² of component (C) each have 1 to 1 carbon atoms.
The vulcanized composition according to claim 1, wherein the vulcanized composition has 20 unsubstituted or neutrally substituted alkyl groups.