WO1996032428A1

WO1996032428A1 - Fluoroelastomer

Info

Publication number: WO1996032428A1
Application number: PCT/JP1995/000712
Authority: WO
Inventors: Michio Kasahara; Hiroshi Saitoh; Kenichi Hayashi
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1993-10-15
Filing date: 1995-04-12
Publication date: 1996-10-17

Abstract

A fluoroelastomer which is composed of vinylidene fluoride units and hexafluoropropylene units in a weight ratio ranging from 40:60 to 80:20, has a limiting viscosity number [θ] of 60-100 ml/g, is of a multipeak type wherein the molecular weight distribution curve has two or more peaks, and has a ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of 20 to 25, and wherein 0.6-2.0 wt.% of iodine per 100 wt.% of the elastomer is bonded to the molecular chain terminal of the polymer corresponding to the peak on the low-molecular-weight side of the molecular weight distribution curve. As compared with conventional fluoroelastomers, the invention elastomer has equivalent physical properties and excellent extrudability, thus being suitable as the material of automotive fuel hose, filler hose, and in-tank hose.

Description

Harm

Fluorine-containing elastomer

Technical field

The present invention relates to a novel fluorine-containing elastomer. More specifically, it has excellent heat resistance, solvent resistance, and chemical resistance equivalent to those of conventionally known fluorine-containing elastomers, but also has high tensile strength, excellent compression set resistance, and gasoline permeability. The present invention relates to a fluorine-containing elastomer which is small, does not easily extract low molecular weight components in a solvent, and has excellent extrudability. Therefore, the fluorinated elastomer of the present invention is suitable as a material for a fuel hose, a filler hose, an in-tank hose, and the like of an automobile, for example.

Background art

Since the fluorinated elastomers are extremely superior in heat resistance, solvent resistance, and chemical resistance compared to other general-purpose elastomers, they can be used in various industrial fields, such as general machinery, pollution-related sectors, automobiles, ships, aircraft, Used in hydraulic equipment, such as O-rings, gaskets, oil seals, diaphragms, valves, hoses, rolls, and sheet materials.

However, fluorine-containing elastomers generally have a drawback that they are difficult to process, and various proposals have been made to solve this problem. For example, a method of producing a vinylidene fluoride copolymer having a wide molecular weight distribution containing a low molecular weight polymer and a high molecular weight polymer by a continuous emulsion polymerization method in which a chain transfer agent is periodically added (Japanese Patent Publication No. No. 1-25554), a method of producing a vinylidene fluoride copolymer having a bimodal molecular weight distribution by a cascade type two-tank continuous emulsion polymerization method However, the fluorine-containing elastomer obtained by such a continuous production method has a remarkably wide molecular weight distribution, and the hose has to be formed by extrusion molding. In the case of molding, etc., since the die size is large and a polymer having a very low molecular weight is contained, the physical properties of the vulcanized product such as tensile strength are not satisfactory.

Therefore, in order to solve the problems in extrusion molding, fluorine-containing elastomers having a specific multi-peak molecular weight distribution have been proposed (Japanese Patent Application Laid-Open Nos. Hei 4-210, 1988 and Hei 4-125). No. 8614). In addition, a fluorine-containing elastomer having a specific multi-peak molecular weight distribution and containing bound iodine is vulcanized using a combination of polyol vulcanization and Z or polyamine vulcanization with peroxide vulcanization to achieve mechanical strength and compression set. Studies have been made to improve the solvent and to reduce the solvent extractability (Japanese Patent Application Laid-Open No. 2-160810).

However, in any case, none of the properties of the extruded product and the vulcanized product can be sufficiently satisfied.

The present inventors have previously proposed a fluorinated elastomer (Japanese Patent Application Laid-Open No. 2-160810). Based on the present invention, the processability, especially the extrudability, has been improved.

An object of the present invention is to provide excellent heat resistance, solvent resistance, and chemical resistance equivalent to those of conventionally known fluorine-containing elastomers, high tensile strength, excellent compression set resistance, and gasoline permeability. The present invention relates to a fluorinated elastomer which is small in size, hardly extracts low molecular weight components into a solvent, and has excellent extrudability.

Disclosure of the invention

That is, the present invention relates to (a) (a) vinylidene fluoride unit (hereinafter referred to as Below, abbreviated as VdF unit) and the weight ratio of (b) hexafluoropropylene unit (hereinafter abbreviated as HFP unit) is 40:60 to 80:20. ["] Is 60 to 100 ml, (c) molecular weight distribution is a multi-peak type formed from two or more peaks, and (2) weight average molecular weight (Mw) and number average molecular weight (Mn) MwZMn is 2

(E) 0.6 to 2.0% by weight of iodine per 100% by weight of the fluorinated elastomer is the polymer chain terminal of the polymer derived from the low molecular weight side peak of the molecular weight distribution. A fluorine-containing elastomer characterized by being combined with:

0 BEST MODE FOR CARRYING OUT THE INVENTION

The fluorine-containing elastomer of the present invention needs to have a weight ratio of (a) VdF unit to (b) HFP unit of 40:60 to 80:20.

If the VdF unit is smaller than this, the polymerization rate becomes extremely slow, and if it is larger than this, the obtained polymer becomes 榭 8-shaped and the elastomer elasticity is reduced. ₅ Further, if necessary, (c) a tetrafluoroethylene unit (hereinafter abbreviated as TFE unit) may be added to the monomer units (a), (b) and (c) in an amount of 35% by weight. It is effective within the range not exceeding%. Still more preferably in the range of, (a) VdF units and (b) HFP units and monomer one unit (a), (b) and 10 to 30% by weight of (c) TFE single _0-position, relative to the total weight of (c) And the weight ratio of (a) VdF units to (b) HFP units is from 42:58 to 65:35.

In the fluorinated elastomer of the present invention, it is necessary that the intrinsic viscosity number [], which is an index of the molecular weight, is 60 to 100 ml Zg. If this [] is less than 60 m 1 / g, the tackiness during roll kneading becomes large, If it exceeds 0 O m 1, the fluidity decreases, and it is difficult to obtain good extrusion. A particularly preferred intrinsic viscosity number is 70 to 9 Om1Zg.

In the fluorine-containing elastomer of the present invention, it is necessary that the molecular weight distribution is a multi-peak type formed from two or more peaks. When the molecular weight distribution is a single peak type, it is extremely difficult to control the ratio between the low molecular weight polymer and the high molecular weight polymer, so that it is difficult to obtain good extrusion moldability, which is the object of the present invention. . The molecular weight distribution of the fluorine-containing elastomer of the present invention is composed of a low molecular weight peak having a molecular weight of 50,000 or less and a high molecular weight peak having a molecular weight of 50,000 or more. Low molecular weight side polymers are required to improve flowability, and high molecular weight side polymers are required to maintain the green strength of the fluorinated elastomer formulation.

Further, in the present invention, in order to carry out combined vulcanization, it is necessary that 0.6 to 2.0% by weight of iodine is bound to the terminal of the polymer chain of the low molecular weight side polymer. The bound iodine is easily liberated during peroxide vulcanization to form a radical at the polymer chain end, and this radical becomes a bridge point.

On the other hand, there is no regulation on the polymer chain end of the polymer having a high molecular weight side, and vulcanization of polyol and vulcanization or polyamine are performed.

As described above, a polymer having a high molecular weight is crosslinked by polyol vulcanization and Z or polyamine vulcanization, and a polymer having a low molecular weight is simultaneously crosslinked by peroxide vulcanization. The reaction proceeds, resulting in a molded product with high tensile strength, excellent compression set resistance, low gasoline permeability, and low extraction of low molecular weight components into the solvent. As a method for introducing iodine which can be a bridging point to the polymer chain terminal, a method using an iodine compound as a chain transfer agent (JP-B-63-41928, JP-A-60-221409, etc.) is effective.

The iodine bound to the polymer chain end of the low molecular weight side polymer is in the range of 0.6 to 2.0% by weight based on 100% by weight of the fluorine-containing elastomer. Is insufficient, and even if it exceeds 2.0% by weight, there is no substantial effect of increasing iodine. A particularly preferred iodine range is 0.8 to: L.6% by weight.

In the fluorine-containing elastomer of the present invention, the ratio MwZMn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) needs to be 20 to 25. If the MwZMn is less than 20, the molecular weight distribution is not widened, and the extrudability, such as extrusion speed and extruded skin, is poor.If it exceeds 25, ultra-high molecular weight polymers and ultra-low molecular weight polymers increase. The time dice is worse. Particularly preferred MwZMn is in the range of 21-23. The fluorine-containing elastomer of the present invention can be produced, for example, by blending a high-molecular weight polymer and a low-molecular weight polymer, which are produced separately, respectively, or can be produced by an emulsion polymerization method, a suspension polymerization method, It can also be produced by adding an iodine compound such as a chain transfer agent such as iodomethane or 1,4-jodoperfluorobutane during polymerization by a solution polymerization method.

Next, a method for producing the fluorine-containing elastomer of the present invention will be described by taking a suspension polymerization method as an example. First, a predetermined mixed monomer (prepared monomer) is dispersed in an aqueous medium, the pressure is preferably set in the range of SSO kgZcm ² 'G, and a suspension stabilizer and an oil-soluble catalyst dissolved in an inert organic solvent. The temperature is preferably maintained at 50 to 80 ° C while mechanically stirring to initiate polymerization. Start. Since the pressure decreases as the polymerization proceeds, a new mixed monomer (additional monomer) is added so as to keep the pressure preferably within a range of 5 to 30 kgZcm ² · G, and the polymerization is advanced. The composition of the monomer units in the generated fluorinated elastomer is determined by the relationship between the charged monomer composition and the additional monomer composition. The composition of the charged monomer and the composition of the additional monomer are measured by gas chromatography, and the composition of the monomer unit in the fluorinated elastomer is measured by ¹⁹ F-NMR after dissolving the elastomer in acetone. Further, during the polymerization, the molecular weight distribution is adjusted and the bound iodine is introduced into the polymer chain terminal by adding the iodine compound agent.

The turbidity stabilizer used in this suspension polymerization method is preferably methylcellulose. As the oil-soluble catalyst, dialkyl peroxydicarbonate such as diisopropyl peroxydicarbonate (hereinafter abbreviated as IPP) is preferable because it has a high decomposition temperature. Examples of the inert organic solvent include 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1-dichlorobenzene, 11-fluoroethane (hereinafter abbreviated as R-141b), 1.3-dichloro- 1, 1, 2, 2, 3-pentafluoropropane (hereinafter abbreviated as R-225 cb), and R-141 b. R-225 cb having a small ozone depletion potential is more preferable.

Although the fluorine-containing elastomer of the present invention can be vulcanized with a polyol, a polyamine or a peroxide, vulcanization in combination is desirable to achieve the object of the present invention. As a vulcanization method using a combination of polyol vulcanization and peroxide vulcanization, a fluorine-containing elastomer, (d) a polyhydroxy aromatic compound, (e) a vulcanization accelerator, and (f) a divalent metal water Oxides and di- or divalent metal oxides, (g) organic peroxides, (h) polyfunctional unsaturated compounds, and If necessary, kneading other excipients, extruding, heating and vulcanizing may be used.

Examples of the component (d) boroxyhydroxy aromatic compound include bisphenol AF, bisphenol A, bisphenol S, dihydroxybenzozophenone, hydroquinone, 4,4'-thiodiphenol, and their gold salts. Particularly preferred is bisphenol AF. The mixing ratio is usually 0.1 to 10 parts by weight, preferably 0.6 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer. The reason that the component (d) is in this range is that if less than 0.1 part by weight, a vulcanized molded article cannot be obtained, and if it exceeds 10 parts by weight, elastomeric elasticity is lost. In addition, one kind of these polyhydroxy aromatic compounds may be used, or two or more kinds may be used in combination.

As the vulcanization accelerator of the component (e), phosphonium salts, ammonium salts, iminium salts, sulfonium salts, aminophosphine derivatives and the like are used. For example, benzyltriphenylphosphonium chloride (hereinafter referred to as BT PPC and Abbreviated), methyltriphenylphosphoniummethylmethanephosphonate, tetrabutylammonium fluoride, tetrabutylammonium amide, 8-benzyl-1,8-diazabicyclo (5,4,0)-ゥExamples include butadiene dimethyl chloride, bis (benzyldiphenylphosphine) imidium chloride, and the like, especially BTP PC, 8-benziru-1,8-diazabicyclo (5,4,0) — ゥPreferred are ndecenonium chloride and bis (benzyldiphenylphosphine) imidum chloride. The mixing ratio is usually from 0.05 to 2 parts by weight, preferably from 0.1 to 1 part by weight, per 100 parts by weight of the fluorine-containing elastomer. (E) The component is Within the range, if the amount is less than 0.05 parts by weight, the vulcanization rate becomes extremely slow,

If the amount exceeds 2 parts by weight, the compression set resistance will be significantly deteriorated. These vulcanization accelerators may be used alone or in combination of two or more.

As the divalent gold hydroxide and / or divalent metal oxide of the component (f), for example, oxides and hydroxides of magnesium, calcium, zinc, lead and the like are used, and in particular, oxidation of magnesium and calcium Objects and hydroxides are preferred. The mixing ratio is usually 1 to 30 parts by weight, preferably 2 to 20 parts by weight, per 100 parts by weight of the fluorine-containing elastomer. The reason why the component (f) is in this range is that if the amount is less than 1 part by weight, the vulcanization does not sufficiently proceed, and if it exceeds 30 parts by weight, the compression set resistance deteriorates. These may be used alone or in combination of two or more.

As the organic peroxide of the component (g), an organic peroxide that generates peroxyradical under vulcanization conditions is used. For example, 1,1,1-bis (tert-butyl baroxy) -1,3,5,5 — Trimethylcyclohexane, 1,1-bis (tert-butylbaroxy) cyclohexane, 2,2-bis (tert-butylbaroxy) octane, n-butyl 4,4-bis

(tert-butyl baroquine) phenol, 2,2-bis (161 "1-butylperoxy) butane, 2,5-dimethylhexane-1,2,5-dihydroxyperoxide, g-tert-butylperoxide, tert-butylcumylperoxide, dicumylperoxide, α, α'-bis (ert-butylperoxy-1m-isopropyl) benzene, 2,5-dimethyl-2,5-di (tert-butylveroxy) hexine, 2,5-dimethyl- 2,5-di (tert-butylperoxy) hexyne-1, Benzyl peroxide, tert-butyl peroxybenzene, 2,5-dimethyl-2,5-di (benzoyl peroxy) hexane, tert-butyl peroxy maleate, tert-butyl peroxy isopro Examples of the (g) component include 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, dicumylperoxide, α, α′-bis (tert-butylperoxy-m-1). Isopropyl) benzene, and particularly preferred are 2,5-dimethyl-2,5-di (tert-butylbaroxy) hexane, dicumylperoxide, α, α'-bis (tert-butylperoxy-m-). Isop pill) It is benzene. The mixing ratio is usually 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, per 100 parts by weight of the fluorine-containing elastomer. If the component (g) is in this range, if it is less than 0.05, a sufficient vulcanization rate cannot be obtained, and the mold releasability will be poor. If it exceeds 5 parts by weight, the compression set resistance will be large. This is because it gets worse. Further, one kind of the organic peroxide may be used, or two or more kinds may be used in combination.

Examples of the polyfunctional unsaturated compound as the component (h) include triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacryl formal, triallyl trimellitate, N, N'—m— Phenylene bismaleimide, diaryl phthalate, tetraaryl terephthalamide, tris (diarylamine) -s-triazine, triaryl phosphite, Ν, Ν-diarylacrylamide, etc. Preferred is triallyl isocyanurate. The mixing ratio is usually 0.1 to 10 parts by weight with respect to 100 parts by weight of the fluorinated elastomer. If the component (h) is within this range, a sufficient crosslinking density cannot be obtained if the content is less than 0.1 part by weight. If the amount exceeds 10 parts by weight, the component (h) bleeds on the surface of the elastomer at the time of molding to cause molding failure. A particularly preferred range for component (h) is from 0.2 to 6 parts by weight. The polyfunctional unsaturated compound may be used alone or in combination of two or more.

Further, in the fluorinated elastomeric vulcanizing composition of the present invention, if necessary, other components such as carbon black, austin black, graphite, silica, clay, diatomaceous earth, talc, wollastonite, and calcium carbonate may be used. , Calcium silicate, calcium fluoride, barium sulfate, etc., sulfone compound, phosphate ester, fatty amine, higher fatty acid ester, fatty acid calcium, fatty acid amide, low molecular weight polyethylene, silicone oil, silicone cone grease, stealine Processing aids such as acid, sodium stearate, calcium stearate, magnesium stearate, aluminum stearate, and zinc stearate, and coloring agents such as titanium white and bengara can be blended. The mixing ratio of the filler is preferably in the range of 0.1 to 100 parts by weight based on 100 parts by weight of the fluorine-containing elastomer, and particularly preferably in the range of 1 to 60 parts by weight. The reason why the content of the filler is within this range is that if the content is less than 0.1 part by weight, there is no effect of blending, and if the content exceeds 100 parts by weight, elastomeric elasticity is lost. The mixing ratio of the processing aid is usually preferably 10 parts or less, more preferably 5 parts or less, per 100 parts by weight of the fluorine-containing elastomer. When the mixing ratio of the processing aid exceeds this range, heat resistance is adversely affected. The mixing ratio of the coloring agent is preferably not more than 50 parts by weight, more preferably not more than 30 parts by weight, based on 100 parts by weight of the fluorine-containing elastomer. The mixing ratio of the coloring agent is within this range because if it exceeds 50 parts by weight, the compression resistance becomes permanent. This is because the strainability deteriorates.

When vulcanization using a combination of polyamine vulcanization and peroxide vulcanization is carried out, instead of (d) the polyhydroxy aromatic compound and (e) the vulcanization accelerator, (h) a polyamine compound, for example, Hexamethylene diamine, hexamethylene diamine rubamate, ethylene diamine rubamate, N, N-dicinnamilidene 1,6-hexamethylene diamine, 4,4'-bis (aminocyclocyclo Xyl) Methane carbamate is preferably used. The mixing ratio is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer. The reason why the component (h) is in this range is that if it is less than 0.1 part by weight, a vulcanized molded article cannot be obtained, and if it exceeds 10 parts by weight, elastomeric elasticity is lost. Further, these polyamine compounds may be used alone or in combination of two or more.

As a method for molding the fluorine-containing elastomer of the present invention, for example, after kneading with an open kneading roll or a closed kneading roll (Banbury mixer, pressurized kneader 1 or the like), a long strip is cut out and applied to an extruder. Thereby, a tube-shaped rod-shaped object can be obtained. It is also possible to carry out molding by injection molding, press molding, calendar molding, or the like. Next Ide, by performing secondary vulcanization necessary, the desired characteristics of the vulcanizates obtained _£ fluorinated elastomer scratch, was determined by the following methods.

(1) Intrinsic viscosity [] is measured at 35 ° C using a capillary viscometer with a 0.1100 ml concentration solution of methyl ethyl ketone.

(2) The molecular weight distribution was measured using a liquid chromatograph [HLC-8020 (manufactured by Tosoh Corporation)] and a column [KF-80M (2 pieces) + KF-800P (p (Column)] (manufactured by Showa Denko KK) and an integrator [AS-8010 (manufactured by Tosoichi Co., Ltd.)], using tetrahydrofuran as a developing solvent, a concentration of 0.1% by weight, and a temperature of 35 °. Measured at C. As the standard polymer for the molecular weight calibration curve, various types of monodisperse polystyrene [MwZMn to 1.2 (max)] (manufactured by Toyo Soda Co., Ltd.) were used. Mn and Mw are measured under the above conditions for measuring the molecular weight distribution.

(3) The hardness of the vulcanized product was measured according to [JIS-A], and the 100% tensile stress, tensile strength and elongation were measured according to JIS-K6301.

(4) The compression set was measured at a temperature of 150 and 70 hours according to JIS-K6301.

(5) The extrusion test was performed using a Brabender Extruder 1 ODW (D = 19.1 mm, L / D = 10) with a tube die (outer diameter 9 mm, inner diameter 8 mm), and a screw temperature. The test was performed under the conditions of 80, a head temperature of 100 ° C., and a screw rotation speed of 50 rpm. The extruded skin was visually rated on a scale of 5 (from 5 to 1 in descending order) based on the fineness of the surface skin. The extrusion speed was calculated from the discharge amount per unit time.

Example 1

Purging the autoclave with an electromagnetic induction stirrer with an internal volume of about 501 sufficiently with nitrogen gas, repeating vacuum-nitrogen filling three times and purging with nitrogen, followed by deoxygenated depressurized water 23.7 kg And 17.7 g of methylcellulose (viscosity 50 cp) as a suspension stabilizer, and kept at a temperature of 50 while stirring at 476 rpm. Next, a mixed monomer consisting of 12.7% by weight of Vd F unit, 79.7% by weight of HFP unit and 7.6% by weight of TFE is charged until it becomes 1 T kg / cm ² 'G. Next, 475 g of an R-141b solution containing 78.3 g of IPP as a catalyst is charged to initiate polymerization. When the pressure drops to 16.5 kgZcm ² 'G due to polymerization, a mixed monomer consisting of 44.1% by weight of VdF unit, 28.2% by weight of HFP unit and 27.7% by weight of TFE is added, and the pressure is reduced again to 17 kgZcm ² '. Return to G. _T polymerization initiator after repeating the polymerization reaction such operations, at the time of the lapse of 5 hours, was added the job one Dometan 533 g, likewise further Gun polymerization reaction pressure 16.5~17 k gZcm ² * G, The polymerization reaction is carried out for a total of 12.5 hours. After the completion of the polymerization reaction, the remaining mixed monomer is purged, and the obtained suspension is dehydrated with a centrifuge, washed thoroughly with water, and then dried in vacuo at 100 ° C to obtain 31.9 kg of a fluorine-containing elastomer. . The fluorine-containing elastomer had [7?] Of 89 m 1 Zg, 43.5% by weight of VdF unit, 27.8% by weight of HFP unit and 27.3% by weight of TFE unit, and contained 1.4% by weight of iodine. The molecular weight distribution is formed from two peaks, with an MwZMn of 23.0.

100 parts by weight of the fluorinated elastomer was wound on an open kneading roll, and 13 parts by weight of SRF carbon black “Seast S” manufactured by Tokai Carbon Co., Ltd. 6 parts by weight of calcium hydroxide “Calbit” manufactured by Omi Chemical Industry Co., Ltd. Kyowa Chemical Industry Co., Ltd. Highly active magnesium oxide 3 parts by weight of Kiomag 150, 1.25 parts by weight of bisphenol AF, and 0.7 parts by weight of BTPP C. Next, Nippon Yushi Co., Ltd. product organic peroxide "Perhexa 25B-40 (containing 40% by weight of 2,5-dimethyl-2,5-di (tert-butylbaroxy) hexane") 0.7 part by weight Knead 0.6 parts by weight of triaryl isocyanurate “TA IC” manufactured by Nippon Kasei Co., Ltd., and leave it overnight to ripen it. Then, after re-kneading, put it into an extrusion test, put it in a mold, press vulcanize it at a temperature of 160 for 45 minutes to form a 2 mm thick sheet and a test piece for measuring compression set, and perform various tests .

Table 1 shows the extrusion characteristics of the compound thus obtained and the physical properties of the vulcanized molded product.

Example 2

The same procedure as in Example 1 was repeated except that “Perhexa 25B-40” was replaced by an organic peroxide manufactured by NOF Corporation “Park Mill D-40 (containing 40% by weight of dicumyl peroxide)”. Perform the test. Table 1 shows the results.

Comparative Example 1

Instead of the fluorinated elastomer of Example 1, (1? Unit 42.2 wt%, HFP unit 30.7 wt% and TFE unit 26.2 wt%, iodine content 0.9 wt%, in] is 124 ml Various tests are conducted in the same manner as in Example 1 except that a fluorine-containing elastomer having a Zg and a molecular weight distribution formed from two peaks and having MwZMn of 18.8 is used.

Comparative Example 2

Instead of the fluorine-containing elastomer of Example 1, 43.7% by weight of VdF unit, 29.2% by weight of HFP unit and 26.6% by weight of TFE unit were used, the iodine content was 0.5% by weight, and [77] was 8 lm 1 / g. Various tests are carried out in the same manner as in Example 1 except that a fluorine-containing elastomer having a molecular weight distribution formed from two peaks and having Mw / Mn of 22.7 is used. Table 1 shows the results. 卖 Example 1 窦 Example 'J 9 £ d Comparative Example 1 Comparative Grain Example 2 Vulcanized wit tj tyj

100¾ Tensile stress 34 34 97 Tensile strength 194 1 95 192 166 Oil oil OOv 4 * ί

Hardness [JIS-A] 69 69 69 67 Compression set 33 32 32 52 Extrusion properties

Extrusion speed 160 160 120 150 Extruded skin 5 5 4 5 Industrial applicability

The fluorinated elastomer of the present invention has a high tensile strength, excellent compression permanent distortion resistance, and extrudability (even if the extrusion speed is increased, the fluorinated elastomer comprises the fluorinated elastomer of the present invention). It has excellent extruded skin), and is suitable as a material for automotive fuel hoses, filler hoses, in-tank hoses, etc., and has an extremely large industrial value.

Claims

The scope of the claims

1. The weight ratio of (a) (a) vinylidene fluoride unit to (b) hexafluoropropylene unit is 40:60 to 80:20, and (mouth) intrinsic viscosity number [77] is 60 ~: I 00m (C) a multi-peak type in which the molecular weight distribution is formed from two or more peaks, and (2) the ratio MwZMn between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 20 (E) 0.6 to 2.0% by weight of iodine with respect to 100% by weight of the fluorinated elastomer is a polymer chain of a polymer derived from a low molecular weight peak having a molecular weight distribution. A fluorine-containing elastomer characterized by being bonded to the terminal.