JPH06263952A - Fluoroelastomer composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in safety and processability, etc., by incorporating a three-component copolymer derived from tetrafluoroethylene, etc., with a specific bisaminophenyl compound as curing agent. CONSTITUTION:This fluoroelastomer composition can be obtained by incorporating (A) 100 pts.wt. of a three-component copolymer derived from (1) 30-75mol% of tetrafluoroethylene, (2) 70-30mol% of a perfluoro(lower alkyl-vinylether) and (3) 1-2wt.% of a perfluoro(omega-cyanoalkyl vinylether) or the formula CF2= CFO-(CF2)nCN ((n) is 2-12) with (B) 1-2 pts.wt. of a bisaminophenyl compound of the formula (A is 1-6C alkylidene, 1-10C perfluoroalkylidene, SO2, O, etc.; X and Y are each OH or amino group) as curing agent. The copolymerization for preparing the component A is pref. emulsion polymerization in an aqueous medium using a free radical generator.

Description

Detailed Description of the Invention

[0001]

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]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 59-109546 discloses tetrafluoroethylene, perfluoro (methyl vinyl ether).
And the general formula CF ₂ = CF [OCF ₂ CF (CF ₃ )] nO (CF ₂ ) mCN n: 1 to 2, m: 1 to 4 of cyano (perfluorovinyl ether) 3
The original copolymer has the general formula (Here, A is an alkylidene group having 1 to 6 carbon atoms, and 1 to 1 carbon atoms.
A perfluoroalkylidene group of 0, a SO ₂ group, an O group, a CO group or a carbon-carbon bond that directly bonds 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 above terpolymer is synthesized through many steps as described in US Pat. No. 4,138,426. Therefore, it cannot be said that the raw material is industrially advantageous. Also, the 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 ═CFO (CF ₂ ) nCN (n: 2
To 12), a terpolymer copolymerized with perfluoro (ω-cyanoalkyl vinyl ether) as a cross-linking site monomer is described, and the cross-linking can be performed using tetraphenyl tin. Have been described.

The above-mentioned perfluoro (ω-cyanoalkyl vinyl ether) used as a comonomer component of this terpolymer can be easily synthesized from the corresponding carboxylic acid ester with good selectivity. Therefore, although it is a compound that can be industrially used, the obtained terpolymer is crosslinked by cyclization trimerization of a cyano group with tetraphenyltin. In addition to requiring press vulcanization for a long time, there are problems in industrial use in terms of crosslinking, such as using highly toxic tetraphenyl tin as a crosslinking agent and using expensive silver oxide as an accelerator. Furthermore, it is not satisfactory in terms of compression set at high temperature.

[0006]

The object of the present invention is a copolymer obtained by copolymerizing a cross-linking site monomer which can be easily synthesized with a good selectivity and is commercially available. It is an object of the present invention to provide a fluorine-containing elastomer composition which gives a vulcanized rubber having good processability and physical properties by using a crosslinking agent which has no problem in terms of safety.

[0007]

The object of the present invention is as follows.
Tetrafluoroethylene, perfluoro (lower alkyl vinyl ether) and perfluoro represented by the general formula CF ₂ ═CFO (CF ₂ ) nCN (where n is an integer of 2 to 12)
(ω-Cyanoalkyl vinyl ether) terpolymer, the general formula (Here, A is an alkylidene group having 1 to 6 carbon atoms, and 1 to 1 carbon atoms.
A perfluoroalkylidene group of 0, a SO ₂ group, an O group, a CO group or a carbon-carbon bond that directly bonds two benzene rings, and X and Y are a hydroxyl group or an amino group) This is achieved by a fluorine-containing elastomer composition containing a compound as a curing agent.

Tetrafluoroethylene, perfluoro
(Lower alkyl vinyl ether) and perfluoro (ω-
As a terpolymer of (cyanoalkyl vinyl ether), tetrafluoroethylene and perfluoro (lower alkyl vinyl ether) are copolymerized with about 30 to 75 mol% and about 70 to 30 mol%, respectively, and about 0.5 to 5 Mol%,
Preferably, about 1-2 mol% of perfluoro (ω-cyanoalkyl vinyl ether) copolymerized as a crosslinking site monomer is used. In this terpolymer,
It is also possible to copolymerize various vinyl compounds and fluorinated olefins which do not inhibit the copolymerization reaction and do not impair the vulcanized physical properties.

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, but a terpolymer having a higher molecular weight is used. In order to obtain a coalescence, it is preferable to use an emulsion polymerization method.

In 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 thiosulfate, sodium salts and potassium salts. It is also used as a redox system in combination with a reducing agent consisting of As the emulsifier, an ammonium salt of 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.

In the copolymerization reaction, a predetermined amount of each monomer is charged into the reactor at one time and then the polymerization reaction is carried out, or the monomers are added to the reactor at a constant ratio under a constant pressure. It can be carried out by any of the uniform partial polymerization method, but the latter polymerization reaction method is preferable to obtain a copolymer having good physical properties, in which case the uniform partial polymerization pressure is about 2
The polymerization temperature is maintained at about 50 kg / cm ² G and the polymerization temperature 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 and 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 in the terpolymer, for example, the following compounds are added in an amount of about 0.5 per 100 parts by weight of the terpolymer.
-5 parts by weight, preferably about 1-2 parts by weight. [Bis (aminophenol) AF described below]

In the fluorine-containing elastomer composition containing the above-mentioned respective components as essential components, inorganic fillers such as carbon black and silica, oxides of divalent metals, hydroxides, stearates, litharge, etc. can be received. An acid agent and other necessary compounding agents are appropriately compounded. The composition is prepared by kneading using an open roll or the like, and the crosslinking thereof is about
It is carried out by heating at 160 to 250 ° C for about 10 to 60 minutes. When secondary vulcanization is performed, it is preferable to perform it in an inert atmosphere such as a nitrogen gas atmosphere.

[0015]

Industrial Applicability According to the present invention, a copolymer obtained by copolymerizing a crosslinking site monomer that can be easily synthesized with a good selectivity, is generally commercially available, and is problematic in terms of safety. There is provided a fluorine-containing elastomer composition which gives a vulcanizate of a rubber having good processability and physical properties by using a crosslinking agent which does not exist.

[0016]

EXAMPLES The present invention will now be described with reference to examples.

[0017] in a stainless steel autoclave of Example 1 volume 500 ml, distilled water 200 ml, were charged ammonium perfluorooctanoate 2.5g and _{Na 2 HPO 4 · 12H 2 O} 4.4g, internal and substituted nitrogen gas, The pressure was then reduced. About this autoclave
After cooling to -50 ℃, perfluoro (5-cyanopentyl vinyl ether) [FCVE] 6.4g Perfluoro (methyl vinyl ether) [FMVE] 72g Tetrafluoroethylene [TFE] 32g were charged in sequence and the temperature was raised to 50 ℃. After, sodium sulfite
0.75 g and ammonium persulfate (3.75 g) were charged as 25 ml aqueous solutions to initiate the polymerization reaction. After continuing the polymerization reaction for 20 hours, the unreacted gas was purged, the aqueous latex formed therein was taken out, salted out and dried to obtain 18.0 g of a white rubber-like terpolymer A.

From the results of infrared absorption analysis, this terpolymer A was found to have TFE 69.5 mol%, FMVE 30.3 mol% and FCVE.
(Characteristic absorption of nitrile group 2268 cm ⁻¹ ) It had a copolymer composition of 0.2 mol%.

Reference Example 2 In Reference Example 1, FCVE amount was 8.2 g, FMVE amount was 83 g, T
The FE amount was changed to 28 g, and 8 hours after the initiation of polymerization, the same amounts of sodium sulfite aqueous solution and ammonium persulfate aqueous solution were added again. The obtained white rubber-like terpolymer B was 36.4 g, and the copolymer composition was TFE 61.8 mol%, FMVE 37.7 mol% and FCVE 0.5 mol%.

Reference Example 3 In Reference Example 2, the polymerization temperature was changed to 65 ° C., and 41.5 g of a white rubber-like terpolymer C was obtained. Its copolymer composition is T
It was FE 58.6 mol%, FMVE 40.7 mol% and FCVE 0.7 mol%.

Reference Example 4 In Reference Example 2, the FCVE amount was 12.1 g and the polymerization temperature was 65 ° C.
To obtain 31.2 g of a white rubber-like terpolymer D.
The copolymer composition was 62.1 mol% TFE, 36.8 mol% FMVE and 1.1 mol% FCVE.

Reference Example 5 In Reference Example 2, FCVE amount was 16.4 g and polymerization temperature was 65 ° C.
To give 22.4 g of a white rubber-like terpolymer E.
The copolymer composition was 67.7 mol% TFE, 30.8 mol% FMVE and 1.5 mol% FCVE.

Reference Example 6 Distilled water was placed in a stainless steel autoclave having a volume 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 ℃, tetrafluoroethylene [TFE] 30g Perfluoro (methyl vinyl ether) [FMVE] 50g Perfluoro (5-cyanopentyl vinyl ether) [FCVE] 4.6g was charged in sequence and the temperature was raised to 60 ℃. After, sodium sulfite
1.66 g and 9.08 g of ammonium persulfate were charged as an aqueous solution of 50 ml to initiate the polymerization reaction.

During the polymerization reaction, TFE was 27 g / hr and FMVE was 43 g / h.
r and FCVE were added separately at a flow rate of 4.0 g / hr, and the pressure inside the autoclave was maintained at 9 kg / cm ² G. After 10 hours from the start of polymerization, the addition was stopped, and the state was kept for 1 hour.
After cooling the autoclave and purging the residual gas, the aqueous latex was taken out.

The aqueous latex taken out (solid content concentration 2
(8% by weight) was frozen, washed with 10% ethanol, dried under normal pressure at 70 ° C. for 12 hours, and further dried under reduced pressure at 120 ° C. for 8 hours to obtain 700 g of a white rubber-like terpolymer F. Its copolymer composition is
It was TFE 55.9 mol%, FMVE 42.7 mol%, and FCVE 1.4 mol%. Further, its reduced viscosity ηsp / c [measured at 35 ° C. for a 1% by weight solution of perfluoro (2-butyltetrahydrofuran)] was 1.04 ml / 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
Press vulcanize for 15 minutes at ℃, and then use Curastometer V
When measuring the vulcanization torque value with (Orientec), it is 0.5k.
A rise in g · cm was observed, confirming that it was vulcanized.

Examples 2 to 4 In Example 1, instead of the terpolymer A, the same amount of the terpolymer C, D or E was used, and the 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 vulcanizate are shown in the following Table 1 together with the torque increase width. Table 1 Example 2 Example 3 Example 4 Terpolymer C DE E Torque rise width (kgcm) 3.1 3.9 4.8 Strength at break (kgf / cm ² ) 175 182 180 Elongation at break (%) 220 173 160

Examples 5-6 100 parts by weight of terpolymer F Bis (aminophenol) AF 1 〃 (Example 5) 2 〃 (Example 6) MT carbon black 20 〃 Two rolls of each of the above ingredients Knead on a rubber mill, 180
Primary vulcanization at 30 ° C for 30 minutes and 210 ° C for 18 hours-28
Two-stage secondary (oven) vulcanization was performed at 8 ° C for 18 hours. Normal state properties and compression set (ASTM method
B, P24 O-rings; 275 ° C., 70 hours) are shown in Table 2 below along with the torque increase range. Table 2 Example 5 Example 6 Torque rise width (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

Comparative Example Blend (parts by weight) Blend Formula I Blend Formula II Terpolymer B 100 100 Tetraphenyltin 6 MT Carbon Black 10 10 Silver Oxide 4.8 The above blend components were kneaded on a two-roll rubber mill. , 180
Vulcanization was carried out at ℃ for 2 hours, but no increase in the vulcanization torque value was observed with Curastometer V.

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[Procedure amendment]

[Submission date] February 21, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

The extracted aqueous latex (solid content concentration 28% by weight) is frozen and washed with 10% ethanol,
After drying under atmospheric pressure at 0 ° C. for 12 hours and further under reduced pressure at 120 ° C. for 8 hours, 700 g of a white rubber-like terpolymer F was obtained. The copolymer composition is TFE55.9 mol%, FMV
E was 42.7 mol% and FCVE was 1.4 mol%. Further, its reduced viscosity ηsp / c [measured at 35 ° C. for a 1 wt% solution of perfluoro (2-butyltetrahydrofuran)] was 1.04 dl / g .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029] Knead each of the above ingredients on a two-roll rubber mill,
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 TFE 57.3 mol%, FMVE 39.6 mol% and
And CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂
CN having a white rubber-like composition having a copolymerization composition of 3.1 mol%
Terpolymer G (reduced viscosity ηsp / c = 0.44dl /
g) 100 parts by weight, MT carbon black 15 parts by weight
And 1 part by weight of bis (aminophenol) AF,
Kneaded with a roll mill. About the kneaded product, 180 ℃, 3
Primary (press) vulcanization for 0 minutes and 250 ° C for 24 hours
Secondary (oven) vulcanization of vulcanized products
And compression set were measured.

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Claims (1)

[Claims] 1. Tetrafluoroethylene, perfluoro
(Lower alkyl vinyl ether) and the general formula CF ₂ = CFO
A perfluoro (ω-cyanoalkyl vinyl ether) terpolymer represented by (CF ₂ ) nCN (where n is an integer of 2 to 12) has the general formula (Here, A is an alkylidene group having 1 to 6 carbon atoms, and 1 to 1 carbon atoms.
A perfluoroalkylidene group of 0, a SO ₂ group, an O group, a CO group or a carbon-carbon bond that directly bonds 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.