JP3375404B2 - Fluorine-containing elastomer composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing elastomer composition. More specifically, it relates to a crosslinkable composition of a fluorine-containing elastomer having a cyano group as a crosslinkable group. [0002] JP-A-59-109546 discloses tetrafluoroethylene, perfluoro (methyl vinyl ether).
And cyano (perfluorovinyl ether) 3 represented by the general formula CF ₂ = CF [OCF ₂ CF (CF ₃ )] nO (CF ₂ ) mCN n: 1 to 2, m: 1 to 4
The general formula is added to the copolymer. (Where A is an alkylidene group having 1 to 6 carbon atoms, 1 to 1 carbon atoms)
A perfluoroalkylidene group, a SO ₂ group, an O group, a CO group or a carbon-carbon bond directly bonding two benzene rings, and X and Y are a hydroxyl group or an amino group. A fluorine-containing elastomer composition containing a compound as a curing agent is described. However, cyano (perfluorovinyl ether) copolymerized as a crosslinking site monomer of the terpolymer is synthesized through many steps as described in US Pat. No. 4,138,426. Therefore, it cannot be said that it is an industrially advantageous raw material. Further, compression set at high temperature is not satisfactory. On the other hand, US Pat. No. 3,546,186 discloses that tetrafluoroethylene and perfluoro (methyl vinyl ether) have the general formula CF ₂ CCFO (CF ₂ ) nCN (n: 2
Terpolymers obtained by copolymerizing perfluoro (ω-cyanoalkylvinyl ether) represented by formulas (1) to (12) as crosslinking site monomers are described, and the crosslinking thereof may be performed using tetraphenyltin. Has been described. The above perfluoro (ω-cyanoalkyl vinyl ether) used as a comonomer component of the terpolymer can be easily synthesized from the corresponding carboxylic acid ester with a good selectivity. Although it is a compound that can be industrially used, the obtained terpolymer is crosslinked by cyclization and trimerization of a cyano group with tetraphenyltin. In addition to the need for press vulcanization for a long time, there is a problem in industrial use in terms of crosslinking, such as the use of highly toxic tetraphenyltin as a crosslinking agent and the use of expensive silver oxide as an accelerator. Further, the compression set at high temperature is not satisfactory. SUMMARY OF THE INVENTION An object of the present invention is to provide a copolymer obtained by copolymerizing a crosslinking site monomer which can be easily synthesized with a good selectivity. An object of the present invention is to provide a fluorine-containing elastomer composition which is commercially available and uses a crosslinking agent having no problem in terms of safety and which gives a vulcanized rubber having good processability and physical properties. SUMMARY OF THE INVENTION The object of the present invention is as follows.
Tetrafluoroethylene, a lower alkyl group having 1 to 3 carbon atoms
And a perfluoro (ω-cyanoalkyl vinyl ether) represented by the general formula CF ₂ CCFO (CF ₂ ) nCN (where n is an integer of 2 to 12) To 100 parts by weight of the copolymer, the general formula (Where A is an alkylidene group having 1 to 6 carbon atoms, 1 to 1 carbon atoms)
A perfluoroalkylidene group, a SO ₂ group, an O group, a CO group or a carbon-carbon bond directly bonding two benzene rings, and X and Y are a hydroxyl group or an amino group. 0.5 with compound as curing agent
This is achieved by a fluorine-containing elastomer composition blended in an amount of up to 5 parts by weight . [0008] Tetrafluoroethylene having 1 to 3 carbon atoms
As the terpolymer of perfluoro having a lower alkyl group (lower alkyl vinyl ether) and perfluoro (ω-cyanoalkyl vinyl ether), tetrafluoroethylene and perfluoro (lower alkyl vinyl ether) are each about 30 to 75 mol%. And about 70-30 mol
% Copolymerized, about 0.5 to 5 mol%, preferably about 1 to 5 mol%.
Perfluoro (.omega.-cyanoalkyl vinyl ether) of .about.2 mol% copolymerized as a crosslinking site monomer is used. In the terpolymer, various vinyl compounds, fluorinated olefins, and the like can be copolymerized to such an extent that the copolymerization reaction is not hindered and vulcanization properties are not impaired. The copolymerization reaction is carried out by emulsion polymerization in an aqueous medium, suspension polymerization or solution polymerization in a perfluoro compound solvent using a free radical generator. In order to obtain coalescence, it is preferable to use an emulsion polymerization method. In the emulsion polymerization in an aqueous medium, free radical generators such as ammonium persulfate and potassium persulfate are used. These free radical generators include ammonium salts such as sulfurous acid and thiosulfuric acid, sodium salts and potassium salts. It is also used as a redox system in combination with a reducing agent comprising As the emulsifier, an ammonium salt of a perfluorinated carboxylic acid is generally used, and ammonium perfluorooctanoate is particularly preferably used. Furthermore, Na
PH adjusters such as ₂ HPO ₄ , NaH ₂ PO ₄ , K ₂ HPO ₄ and KH ₂ PO ₄ are also commonly used. [0011] The copolymerization reaction is carried out by a batch charging polymerization method in which a predetermined amount of each monomer is charged into a reactor at a time and then a polymerization reaction is performed, or each monomer is dispensed into the reactor at a constant rate under a constant pressure. The method can be carried out by any of the following uniform dispensing polymerization methods, but the latter polymerization reaction method is preferable in order to obtain a copolymer having good physical properties, in which case the uniform dispensing polymerization pressure is about 2
5050 kg / cm ² G and the polymerization temperature is maintained at about 40-80 ° C. After completion of the polymerization reaction, the obtained aqueous latex is salted out with an aqueous solution of a water-soluble electrolyte substance such as sodium chloride or magnesium chloride, filtered and dried to obtain a terpolymer. it can. Instead of salting out, the aqueous latex may be frozen, filtered and dried. As the bisaminophenyl cross-linking agent represented by the above general formula, which is blended with the terpolymer, for example, the following compound may be used in an amount of about 0.5 per 100 parts by weight of the terpolymer.
To 5 parts by weight, preferably about 1 to 2 parts by weight. [Postscript bis (aminophenol) AF] In the fluorine-containing elastomer composition containing the above components as essential components, inorganic fillers such as carbon black and silica, oxides of divalent metals, hydroxides, stearates, litharges and the like are contained. An acid agent and other necessary compounding agents are appropriately compounded. Preparation of the composition is performed by kneading using an open roll or the like, and the crosslinking thereof is performed by about
It is performed by heating at 160 to 250 ° C. for about 10 to 60 minutes. When performing the secondary vulcanization, it is preferable to perform the secondary vulcanization in an inert atmosphere such as a nitrogen gas atmosphere. According to the present invention, there is provided a copolymer obtained by copolymerizing a crosslinking site monomer which can be easily synthesized with a good selectivity. The present invention provides a fluorine-containing elastomer composition which provides a vulcanized rubber having good processability and physical properties by using a crosslinking agent having no problem in point. Next, the present invention will be described by way of examples. Reference Example 1 In a stainless steel autoclave having a capacity of 500 ml, 200 ml of distilled water, 2.5 g of ammonium perfluorooctanoate and 4.4 g of Na ₂ HPO ₄ .12H ₂ O were charged, and the inside was replaced with nitrogen gas. Then the pressure was reduced. About this autoclave,
After cooling to −50 ° C., perfluoro (5-cyanopentyl vinyl ether) [FCVE] 6.4 g perfluoro (methyl vinyl ether) [FMVE] 72 g tetrafluoroethylene [TFE] 32 g were sequentially charged and heated to 50 ° C. Later, sodium sulfite
0.75 g and 3.75 g of ammonium persulfate were each charged as a 25 ml aqueous solution to start a polymerization reaction. After the polymerization reaction was continued for 20 hours, the unreacted gas was purged, the aqueous latex formed there was taken out, salted out and dried to obtain 18.0 g of a white rubbery terpolymer A. From the results of infrared absorption analysis, this terpolymer A was found to contain 69.5 mol% of TFE, 30.3 mol% of FMVE and FCVE
It had a copolymer composition of 0.2 mol% (characteristic absorption of nitrile group: 2268 cm ⁻¹ ). Reference Example 2 In Reference Example 1, the FCVE amount was changed to 8.2 g, the FMVE amount was changed to 83 g, and T
The amount of FE was changed to 28 g, and 8 hours after the start of the polymerization, the same amount of an aqueous solution of sodium sulfite and an aqueous solution of ammonium persulfate were added again. The obtained white rubbery terpolymer B was 36.4 g, and the copolymer composition was 61.8 mol% of TFE, 37.7 mol% of FMVE, and 0.5 mol% of FCVE. Reference Example 3 In Reference Example 2, the polymerization temperature was changed to 65 ° C., and 41.5 g of a white rubbery terpolymer C was obtained. Its copolymer composition is T
The FE was 58.6 mol%, the FMVE was 40.7 mol%, and the FCVE was 0.7 mol%. Reference Example 4 In Reference Example 2, the amount of FCVE was 12.1 g and the polymerization temperature was 65 ° C.
And 31.2 g of a white rubbery terpolymer D was obtained.
The copolymer composition was 62.1 mol% of TFE, 36.8 mol% of FMVE, and 1.1 mol% of FCVE. Reference Example 5 The procedure of Reference Example 2 was repeated except that the amount of FCVE was 16.4 g and the polymerization temperature was 65 ° C.
And 22.4 g of a white rubbery terpolymer E was obtained.
The copolymer composition was 67.7 mol% of TFE, 30.8 mol% of FMVE, and 1.5 mol% of FCVE. Reference Example 6 Distilled water was placed in a stainless steel autoclave having a capacity of 3 L.
After charging 1.57 L, 27.3 g of ammonium perfluorooctanoate and 23.7 g of Na ₂ HPO ₄ .12H ₂ O, the inside was replaced with nitrogen gas, and then the pressure was reduced. About this autoclave,
After cooling to -50 ° C, tetrafluoroethylene [TFE] 30g perfluoro (methyl vinyl ether) [FMVE] 50g perfluoro (5-cyanopentyl vinyl ether) [FCVE] 4.6g were sequentially charged and heated to 60 ° C. Later, sodium sulfite
1.66 g and 9.08 g of ammonium persulfate were charged as 50 ml aqueous solutions, respectively, to initiate a polymerization reaction. During the polymerization reaction, TFE was 27 g / hr and FMVE was 43 g / h.
r and FCVE were each added at a flow rate of 4.0 g / hr, and the pressure in the autoclave was maintained at 9 kg / cm ² G. Dispensing was stopped 10 hours after the start of the polymerization, and the state was kept for 1 hour.
After the autoclave was cooled and the residual gas was purged, the aqueous latex was taken out. The aqueous latex taken out (solid content concentration 28% by weight) is frozen, washed with 10% ethanol,
After drying under normal pressure at 0 ° C. for 12 hours, the resultant was further dried under reduced pressure at 120 ° C. for 8 hours to obtain 700 g of a white rubbery terpolymer F. The copolymer composition was 55.9 mol% of TFE, FMV
E was 42.7 mol% and FCVE was 1.4 mol%. Further, its reduced viscosity ηsp / c [measured at 35 ° C. of a 1% by weight solution of perfluoro (2-butyltetrahydrofuran)] was 1.04 dl / g . Example 1 100 parts by weight of terpolymer A Bis (aminophenol) AF 2 dicyclohexyl-18-crown-6 0.5 MT carbon black 10 Lisage 2 Two-roll rubber mill containing the above components Knead on, 180
Perform press vulcanization for 15 minutes at
When measuring the vulcanization torque value with (Orientec), 0.5 k
An increase in g · cm was observed, and vulcanization was confirmed. Examples 2 to 4 In Example 1, the same amount of terpolymer C, D or E was used in place of terpolymer A, and primary (press) was performed at 180 ° C. for 1 hour. Vulcanization and secondary (oven) vulcanization at 250 ° C. for 24 hours were performed. The physical properties of the obtained vulcanizates are shown in Table 1 below together with the torque increase. Table 1 Example 2 Example 3 Example 4 Terpolymer C D E Torque rise (kg · cm) 3.1 3.9 4.8 Strength at break (kgf / cm ² ) 175 182 180 Elongation at break (%) 220 173 Examples 5 to 6 100 parts by weight of terpolymer F (bis (aminophenol) AF 1 (Example 5) 2 (Example 6) MT carbon black 20) Two of the above components were used. Knead on a roll rubber mill, 180
Primary (press) vulcanization for 30 minutes at 210 ° C and -28 hours for 210 ° C for 18 minutes
Two-stage secondary (oven) vulcanization was performed at 8 ° C. for 18 hours. Normal physical properties and compression set of the obtained vulcanizate (ASTM method
B, P24 O-ring; 275 ° C., 70 hours) are shown in the following Table 2 together with the torque increase. Table 2 Example 5 Example 6 Torque increase (kg · cm) 9.3 11.9 Hardness (JIS A) 76 78 100% modulus (kgf / cm ² ) 92 132 Strength at break (kgf / cm ² ) 192 194 Elongation at break (%) 180 130 Compression set (%) 22 13 [0029] The above components were kneaded on a two-roll rubber mill,
The vulcanization was carried out at 0 ° C. for 2 hours, but no increase in the vulcanization torque value was observed with Curastometer V. Comparative Example 2 57.3 mol% of TFE, 39.6 mol% of FMVE and
And CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂
CN 3.1% by mole of white rubbery copolymer
Terpolymer G (reduced viscosity ηsp / c = 0.44 dl /
g) 15 parts by weight of MT carbon black per 100 parts by weight
And 1 part by weight of bis (aminophenol) AF
Kneaded with a roll mill. 180 ° C, 3
Primary (press) vulcanization for 0 minutes and 250 ° C for 24 hours
(Oven) vulcanization of the vulcanized product
The properties and compression set were measured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI // (C08F 214/26 C08F 216: 14 216: 14) (56) References JP-A-56-166251 (JP, A) JP-A-59-109546 (JP, A) JP-A-62-15212 (JP, A) JP-A-3-100039 (JP, A) JP-A-59-232137 (JP, A) JP-A-7-3101 ( JP, A) JP-T-5-507763 (JP, A) US Patent 3,546,186 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 27/18 C08F 8/32 C08F 214 / 26 C08L 29/04

Claims (1)

(57) [Claims] [Claim 1] Tetrafluoroethylene having 1 to 3 carbon atoms
Perfluoro having a lower alkyl group (lower alkyl vinyl ether) and a perfluoro compound represented by the general formula CF ₂ CCFO (CF ₂ ) nCN (where n is an integer of 2 to 12)
(ω-cyanoalkyl vinyl ether) terpolymer 100
In the parts by weight , the general formula (Where A is an alkylidene group having 1 to 6 carbon atoms, 1 to 1 carbon atoms)
A perfluoroalkylidene group, a SO ₂ group, an O group, a CO group or a carbon-carbon bond directly bonding two benzene rings, and X and Y are a hydroxyl group or an amino group. 0.5 with compound as curing agent
A fluorine-containing elastomer composition containing up to 5 parts by weight .