JP2010090327A - Fluorine-containing elastomer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorine-containing elastomer composition containing a polyol crosslinkable fluorine-containing elastomer, polyol-based crosslinking agent and quaternary phosphonium salt, having a further quicker vulcanization rate than that of vulcanizing compositions proposed conventionally and capable of substantially shortening an oven vulcanization (secondary vulcanization) time. <P>SOLUTION: This fluorine-containing elastomer composition is provided by containing the polyol crosslinkable fluorine-containing elastomer, polyol-based crosslinking agent and a tetrabutyl phosphonium hydrogen fluoride crosslinking promotor, expressed by general formula: (C<SB>4</SB>H<SB>9</SB>)<SB>4</SB>PF-(HF)<SB>n</SB>[wherein, n is 1 or 2]. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorine-containing elastomer composition. More specifically, the present invention relates to a fluorine-containing elastomer composition comprising a polyol-crosslinkable fluorine-containing elastomer, a polyol-based crosslinking agent and a quaternary phosphonium salt.

The present applicant previously contains a polyol-crosslinkable fluorine-containing elastomer comprising a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, a polyol-based crosslinking agent, and benzyltributylphosphonium chloride or bromide. This vulcanizable composition provides a vulcanizate having a high vulcanization rate and excellent methanol resistance and compression set resistance.
Japanese Patent No. 3887844

  An object of the present invention is a fluorine-containing elastomer composition comprising a polyol-crosslinkable fluorine-containing elastomer, a polyol-based crosslinking agent and a quaternary phosphonium salt, which is further added to the conventionally proposed vulcanizable composition. Another object of the present invention is to provide an apparatus that has a high vulcanization speed and can significantly reduce oven vulcanization (secondary vulcanization) time.

The object of the present invention is to provide a polyol-crosslinkable fluorine-containing elastomer, a polyol-based crosslinking agent, and tetra represented by the general formula (C ₄ H ₉ ) ₄ PF · (HF) _n (where n is 1 or 2). This is achieved by a fluorine-containing elastomer composition containing a butylphosphonium hydrogen fluoride crosslinking accelerator.

  The fluorine-containing elastomer composition according to the present invention is a fluorine-containing elastomer composition described in Patent Document 1 described above, which has a high vulcanization rate at the TDR value of ODR (time to reach 90% of the minimum torque value). Even if the oven vulcanization (secondary vulcanization) time is shortened from 22 hours to 5 hours, for example, normal properties, methanol resistance, low temperature characteristics, compression set resistance characteristics, etc. The effect that a vulcanizate satisfying the above can be obtained is exhibited.

  Polyol vulcanizable fluoroelastomers include highly fluorinated elastic copolymers such as vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, fluorinated Two or more kinds of elastic copolymers such as vinyl, perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), perfluoro (propyl vinyl ether), preferably vinylidene fluoride-hexafluoropropylene copolymer, particularly preferably Vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-perfluoro (Al Vinyl ether) quaternary copolymer is used.

  Examples of the polyol-based crosslinking agent include 2,2-bis (4-hydroxyphenyl) propane (bisnor A), 2,2-bis (4-hydroxyphenyl) perfluoropropane (bisphenol AF), and bis (4-hydroxy Phenyl) sulfone (bisphenol S), 2,2-bis (4-hydroxyphenyl) methane (bisphenol F), bisphenol A-bis (diphenyl phosphate), 4,4'-dihydroxydiphenyl, 2,2-bis (4- Hydroxyphenyl) butane and the like, and preferably bisphenol A, bisphenol AF and the like are used. These may also be in the form of alkali metal salts or alkaline earth metal salts. These polyol-based crosslinking agents are generally used in a proportion of about 0.5 to 10 parts by weight, preferably about 0.5 to 6 parts by weight, per 100 parts by weight of the polyol-based crosslinkable fluorine-containing elastomer.

In the tetrabutylphosphonium hydrogen fluoride represented by the general formula (C ₄ H ₉ ) ₄ PF · (HF) _n , the butyl group can be an n-butyl group, an isobutyl group, a second butyl group or a third butyl group. Tetrabutylphosphonium hydrogen difluoride (n = 1) or tetrabutylphosphonium dihydrofluoride (n = 2) is a known compound, and can be used as a fluorinating agent in halofluorination methods for alkenes. Are known.
JP-A-6-256224

  In the present invention, such tetrabutylphosphonium hydrogen fluoride is used as a crosslinking accelerator at a ratio of about 0.1 to 10 parts by weight, preferably about 0.1 to 2 parts by weight, per 100 parts by weight of the polyol crosslinkable fluorine-containing elastomer. If the proportion of the crosslinking accelerator used is less than this, the intended purpose of the present invention cannot be achieved. On the other hand, if it is used in a proportion higher than this, the elongation characteristics are lowered.

  Each of the above vulcanized components may be directly blended into a fluorinated copolymer elastomer and kneaded, or may be diluted with carbon black, silica, clay, talc, diatomaceous earth, barium sulfate, etc. It is also used as a masterbatch dispersion with a fluorinated copolymer elastomer. In the formulation, in addition to the above components, conventionally known fillers or reinforcing agents (carbon black, silica, graphite, clay, talc, diatomaceous earth, barium sulfate, titanium oxide, wollastonite, etc.), plastic Agents, lubricants, processing aids, pigments and the like can be appropriately blended.

  Vulcanization is carried out by mixing the above components by a commonly used mixing method such as roll mixing, kneader mixing, Banbury mixing, or solution mixing, and then heating. The heating is generally performed by press vulcanization performed at about 100 to 250 ° C. for about 1 to 120 minutes and oven vulcanization (secondary vulcanization) performed at about 150 to 300 ° C. for about 0.5 to 30 hours. Even if the secondary vulcanization time is shortened to about several hours, a vulcanized product having desired characteristics can be obtained.

  Next, the present invention will be described with reference to examples.

Example 1
In an autoclave with an internal volume of 10 L, 6 L of deionized water, 2 g of ammonium perfluorooctanoate and 2 g of sodium hydroxide were charged, and the interior space was sufficiently replaced with nitrogen gas.
Vinylidene fluoride [VdF] 71.0 mol%
Tetrafluoroethylene [TFE] 5.5 mol%
Hexafluoropropene [HFP] 22.0 mol%
Perfluoro (methyl vinyl ether) [FMVE] 1.5 mol%
The mixed gas was injected as an initial charge gas until the internal pressure reached 24 kgf / cm ² G. Thereafter, 10 g of diethyl malonate was injected and the internal temperature was raised to 80 ° C.

  A polymerization initiator aqueous solution in which 5 g of ammonium persulfate was dissolved in 150 g of water was pressed into the autoclave to initiate the polymerization reaction. When the internal pressure decreased to 2.842 MPa, a VdF / TFE / HFP (molar ratio 78.0 / 6.0 / 16.0) mixed gas was injected as an additional gas until the internal pressure reached 2.94 MPa. Every time the internal pressure decreased to 2.842 MPa, the operation of injecting the above-mentioned added gas until the internal pressure reached 2.94 MPa was repeated. After 3 hours from the first addition of the mixed gas after the start of the polymerization reaction, the addition of the mixed gas was terminated, and immediately thereafter, the unreacted gas in the autoclave was purged to stop the reaction. To the obtained aqueous emulsion, 5% potassium alum water was added to coagulate the resulting copolymer, washed with water and dried to obtain 2600 g of a fluorinated copolymer elastomer.

The resulting fluorine-containing copolymer elastomer has a Mooney viscosity ML _{1 + 10} (120 ° C.) (according to ASTM D-1646-82) of 45 pts, and its copolymer composition is VdF 77.5 mol%, TFE 6.0 mol% HFP 16.0 mol%, FMVE 0.5 mol%.

100 parts by weight of the above fluorinated copolymer elastomer Bisphenol AF masterbatch (50% by weight) 4 〃
Tetra (n-butyl) phosphonium hydrogen 0.5 〃
Difluoride (TBPD)
Magnesium oxide 3 〃
Calcium hydroxide 6 〃
Austin Black 25
Silica (Japan Aerosil product Aerosil R972) 10 〃
Bengara (Let's Color Product Brown 401) 5 〃
Note) The master batch is roll kneaded with each component of the master batch and the fluorocopolymer elastomer, and the kneaded product is press vulcanized at 180 ° C for 10 minutes and oven vulcanized at 230 ° C for 5 hours (secondary vulcanization The sheet and the O-ring were vulcanized and molded.

The obtained fluorine-containing copolymer elastomer and vulcanizate were measured for the following items.
ODR: Toyo Seiki oscillating disc rheometer ASTM-100 type, 180
Perform vulcanization at ℃ for 10 minutes and measure the minimum torque value (M _L ), maximum torque value (M _H ), and time to reach 90% torque value of the maximum torque value (Tc90) Normal physical properties: Hard (Shore A) ASTM D-2240-81 compliant
100% modulus ASTM D-412-83 compliant
Tensile strength ASTM D-412-83 compliant
Elongation Compliant with ASTM D-412-83 Methanol resistance: Volume change rate after immersion in methanol at 60 ° C for 70 hours
(A general indicator of resistance to organic solvents)
Low temperature characteristics: TR test according to ASTM D-1329 Compression set: Measured with O-ring with a wire diameter of 3.5 mm compressed at 200 ° C for 70 hours, 25%

Example 2
In Example 1, the secondary vulcanization time was changed to 22 hours.

Example 3
In Example 1, instead of tetra (n-butyl) phosphonium hydrogen difluoride [TBPD], 0.5 part by weight of tetra (n-butyl) phosphonium dihydrogen trifluoride [TBPT] was used.

Example 4
In Example 3, the secondary vulcanization time was changed to 22 hours.

Comparative Example 1
In Example 1, 0.5 parts by weight of benzyltriphenylphosphonium chloride was used instead of tetra (n-butyl) phosphonium hydrogen difluoride [TBPD].

Comparative Example 2
In Comparative Example 1, the secondary vulcanization time was changed to 22 hours.

Comparative Example 3
In Comparative Example 2, 0.52 parts by weight of benzyltributylphosphonium bromide was used instead of benzyltriphenylphosphonium chloride.

  The measurement results in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in the following table.

table
Example Comparative Example
Measurement item 1 2 3 4 1 2 3
[ODR]
M _L (kgcm) 9.2 9.2 9.1 9.1 9.0 9.0 9.4
M _H (kgcm) 65.0 65.1 64.1 64.3 60.4 60.5 65.1
Tc 90 (seconds) 178 177 190 185 245 240 284
[Normal properties]
Hardness (Shore A) (pts) 78 78 78 79 77 79 80
100% modulus (MPa) 9.4 9.4 9.5 9.4 6.1 9.5 10.4
Tensile strength (MPa) 15.0 15.1 14.5 14.5 8.3 14.2 15.0
Elongation (%) 160 160 170 170 160 170 150
[Methanol resistance]
Volume change rate (%) +54 +55 +55 +54 +65 +59 +49
(Low temperature characteristics)
TR-10 (° C) -19.7 -20.0 -19.9 -19.8 -18.9 -19.9 -19.8
TR-70 (° C) -2.2 -2.1 -2.3 -2.0 +0.1 -2.1 -3.1
(TR-10)-(TR-70) (° C) 17.7 17.9 17.6 17.8 19.0 17.8 16.7
(Compression set)
200 ° C, 70 hours (%) 25 24 25 25 38 28 25

Claims (4)

Polyol-crosslinkable fluorine-containing elastomer, polyol-based crosslinking agent, and tetrabutylphosphonium hydrogen fluoride crosslinking represented by the general formula (C ₄ H ₉ ) ₄ PF · (HF) _n (where n is 1 or 2) A fluorine-containing elastomer composition containing an accelerator.   2. The fluorine-containing elastomer composition according to claim 1, wherein the polyol-crosslinkable fluorine-containing elastomer is a vinylidene fluoride-hexafluoropropylene copolymer.   The fluorine-containing elastomer composition according to claim 2, wherein the vinylidene fluoride-hexafluoropropylene copolymer is a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer.   4. The fluorine-containing elastomer composition according to claim 1, wherein the polyol-based crosslinkable fluorine-containing elastomer is used in a proportion of 0.5 to 10 parts by weight and a crosslinking accelerator is used in a proportion of 0.1 to 10 parts by weight per 100 parts by weight of the polyol-crosslinkable fluorine-containing elastomer. .