JPH04258614A - Fluoroelastomer - Google Patents

Abstract

PURPOSE:To obtain a fluoroelastomer having a multi-peak molecular weight distribution and excellent extrudability and properties, and comprising vinylidene fluoride units, hexafluoropropylene units and optionally tetrafluoroethylene units. CONSTITUTION:A fluoroelastomer comprising vinylidene fluoride units (i), hexafluoropropylene units (ii) and optionally 0-35wt.% tetrafluoroethylene units (iii), wherein the weight ratio of units (i) to units (ii) is 40:60 to 80:20, and the elastomer has the following properties: (a) the molecular weight distribution is of a multi-peak type, (b) the molecular weight of the apex of the peak of the highest molecular weight is 350000-550000, (c) the Mw/Mn ratio (wherein Mw is the weight-average molecular weight, and Mn is the number-average molecular weight) is 4-10, (d), the inherent viscosity (eta) is 40-200ml/g, and (e) the ratio (M5/eta) (wherein M5 is the rate (wt.%) of a component of a molecular weight of 50000 or below, and eta is the intrinsic viscosity) is 0.15-9.70.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new fluorine-containing elastomer. More specifically, the present invention relates to a fluorine-containing elastomer that has excellent extrudability and can yield a vulcanizate with excellent heat resistance, oil resistance, and chemical resistance.

0002

BACKGROUND OF THE INVENTION In recent years, there has been a demand for elastomers that have excellent extrusion processability and, in the form of vulcanizates, excellent heat resistance, oil resistance, and chemical resistance such as methanol resistance. A typical use is in automobile fuel hoses. Although fluorine-containing elastomers are excellent materials in terms of heat resistance, oil resistance, and methanol resistance, they are not fully satisfactory in terms of extrudability. If the molecular weight is lowered in an attempt to increase the extrusion speed, vulcanization will not be sufficient and satisfactory physical properties will not be obtained. If the molecular weight is increased until vulcanization is sufficient, the fluidity will deteriorate and the extrusion speed will not be high. A method for solving such a dilemma is proposed in Japanese Patent Laid-Open No. 02-160810. That is, this is a method of making the molecular weight distribution multi-peaked, and is a very effective method for achieving both physical properties and extrusion processability. However, in this method, when the vulcanizing agent and the like are kneaded with a roll or the like, molecular chains may be cut, resulting in a decrease in molecular weight. This is particularly noticeable when a large amount of components with high molecular weights are included. Therefore, there was a problem in that extrusion speed and physical properties varied due to differences in roll kneading operation time and roll gap.

0003

[Problems to be Solved by the Invention] The object of the present invention is to have excellent extrudability, heat resistance, oil resistance, methanol resistance, vulcanization properties, and vulcanization physical properties. The object of the present invention is to provide a fluorine-containing elastomer that does not cause variations in properties or physical properties.

0004

[Means for Solving the Problems] As a result of extensive research in order to solve the above problems, the present inventors have discovered that molecular chain scission occurs in components with molecular weights above a certain specific level. As a result of further research, the present invention was completed. That is, the present invention comprises (a) vinylidene fluoride units, (b) hexafluoropropylene units, and (c) 0
Consisting of ~35% by weight of tetrafluoroethylene units,
and (a) the weight ratio of units to (b) units is 40:60 to 80:20, and the molecular weight distribution is (a) multi-peak type; (b) among the molecular weight peaks, the peak with the highest molecular weight; The molecular weight of the apex of is from 350,000 to 550,000 (c
) The ratio Mw/Mn of weight average molecular weight (Mw) to number average molecular weight (Mn) is 4 or more and 10 or less (d) The intrinsic viscosity number is 40 to 200 ml/g (e) Molecular weight 5
The ratio of the component ratio (M5) of 10,000 or less and the limiting viscosity number ([n]),
The present invention is a fluorine-containing elastomer characterized in that M5/[n] is 0.15 to 0.70.

[0005] The present invention will be explained in detail below. The present invention uses vinylidene fluoride (hereinafter abbreviated as VDF) units, hexafluoropropylene (hereinafter abbreviated as HFP) units,
Unit and optionally tetrafluoroethylene (hereinafter TF
A fluorine-containing elastomer consisting of a unit (abbreviated as E), in which the VD in these fluorine-containing elastomers is
The ratio of F units to HFP units needs to be in the range of 40:60 to 80:20 by weight. The VD
If the amount of F units is less than this, the polymerization rate is extremely slow and it is difficult to obtain a product with a high molecular weight. If the amount is more than this, the resulting fluorine-containing elastomer becomes resin-like and tends to have lower elasticity. In addition, in the ternary fluorine-containing elastomer, the content of TFE units is 35% by weight or less,
The content is preferably in the range of 5 to 25% by weight, and if the content exceeds 35% by weight, the resulting fluorine-containing elastomer tends to have reduced elasticity. Further, the preferred ratio of VDF units to HFP units is 55:45 by weight in the binary fluorine-containing elastomer.
For ternary fluorine-containing elastomers, the ratio is selected from 45:55 to 70:30.

[0006] Furthermore, the fluorine-containing elastomer must have a multi-peak molecular weight distribution. It is difficult to achieve both extrudability and physical properties with a fluorine-containing elastomer that has a one-peak molecular weight distribution. By making the molecular weight multi-peak, the high molecular weight component provides physical properties and the low molecular weight component improves extrudability. By making it a multi-peak type, it becomes possible to satisfy both extrusion processability and physical properties.

Furthermore, among the molecular weight peaks, the molecular weight at the top of the highest molecular weight peak must be between 550,000 and 350,000 or more. The molecular weight of components with a peak molecular weight of 550,000 or more is reduced by kneading with rolls, etc., which causes variations in extrusion speed, extrusion texture, and physical properties. More preferably, it is 500,000 or less. Moreover, if it is less than 350,000, it is difficult to achieve a substantial balance between physical properties and workability. Preferably it is 370,000 or more.

[0008] Furthermore, the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), Mw/Mn, needs to be 4 or more and 10 or less. If it is less than 4, the difference in molecular weight of each of the multiple peaks is too small, making it difficult to control physical properties and extrudability, and the effect of having multiple peaks will not work effectively. Also, 10
Exceeding this is not preferable because the molecular weight of the peak on the low molecular weight side becomes too low, resulting in severe adhesion to the rolls during roll kneading and making vulcanization difficult. More preferably, it is 4-8.

[0009] In addition, the intrinsic viscosity is 40 ml/g or more 20
It is necessary that it is 0 ml/g or less. If the intrinsic viscosity is less than 40 ml/g, the amount of low molecular weight components will be too large, resulting in poor physical properties, as well as increased adhesion to rolls and poor mold releasability. On the other hand, if it exceeds 200 ml/g, fluidity decreases and good extrusion molding becomes impossible. Preferably it is 50 to 150 ml/g.

Furthermore, the ratio M5/[η] of the amount M5 (wt%) of the low molecular weight polymer having a molecular weight of 50,000 or less and the intrinsic viscosity [η] (ml/g) is 0.15 to 0.70, It is preferably in the range of 0.20 to 0.60. M5 and [η] influence each other and influence extrusion moldability, and as M5 increases, extrusion speed and extrusion texture tend to improve, while as [η] increases, extrusion speed and extrusion moldability tend to improve. Both extruded skin tends to deteriorate. Therefore, in order to have good extrusion moldability, M5
The value of /[η] needs to be within the above range. If M5/[η] is less than 0.15, extrusion becomes difficult and the extrusion speed and extrusion surface deteriorate significantly. If it exceeds 0.70, the green strength decreases and changes easily during extrusion molding, and vulcanization There is a risk that the mechanical strength of the object will decrease.

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 that have been produced separately, but it can also be produced by a suspension polymerization method. is advantageous. This is because suspension polymerization tends to yield a polymer with a narrow peak molecular weight distribution, and by combining multiple stages of polymerization, a multi-peak type with a relatively sharp molecular weight distribution can be easily obtained.

[0012] As described above, the suspension polymerization method is suitable for obtaining a multi-peak type polymer having a small content of ultra-high molecular weight polymer as in the present invention. Such a multi-peak type can be obtained by changing the polymerization pressure, adding a catalyst, adding a chain transfer agent, etc. during the polymerization process. The method of adding a chain transfer agent in the step is preferable because the molecular weight distribution can be easily controlled.

In this method using a chain transfer agent, for example, in the case of batch polymerization, a chain transfer agent is not used at all or is added in a small amount at the beginning of the polymerization to form a high molecular weight polymer. A method can be used in which a predetermined amount of polymer is produced and then a large amount of chain transfer agent is added to form a low molecular weight polymer. As the chain transfer agent, conventionally known ones such as lower alcohols and halogen compounds can be used, but because of their particularly high chain transfer ability, iodine compounds such as diiodomethane and diiodoethane, dibromomethane and dibromoethane, etc. Bromine compounds are preferred, particularly iodine compounds such as diiodomethane.

Next, a preferred example of the suspension polymerization method for producing the fluorine-containing elastomer of the present invention will be explained. First, an inert organic solvent in which a predetermined mixed monomer (feed monomer) is dissolved is added to an aqueous medium Further, a suspension stabilizer and an oil-soluble catalyst are added, and the temperature is preferably kept at 50 to 60°C while stirring mechanically, and the pressure is preferably kept constant in the range of 5 to 17 kg/cm2.G. The polymerization is proceeded by adding new mixed monomers (additional monomers) so that the polymerization is as follows. The composition of monomer units in the produced fluorine-containing elastomer is determined by the relationship between the charged monomer composition and the additional monomer composition. The charged monomer composition and additional monomer composition are measured by gas chromatography, and the composition of monomer units in the fluorine-containing elastomer is measured by 19F-NMR after dissolving the elastomer in acetone. Moreover, the molecular weight distribution is adjusted by adding the chain transfer agent during the polymerization.

The inert organic solvent used in this suspension sonopolymerization method is an organic solvent that does not have carbon-hydrogen bonds that tend to cause radical chain transfer.
1,2-trichloro-1,2,2-trifluoroethane is preferred from both performance and economical points of view. Methylcellulose is preferred as the suspension stabilizer. As the oil-soluble catalyst, dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate are preferred because they have a high decomposition temperature.

The fluorine-containing elastomer of the present invention can be vulcanized with a polyamine compound, a polyol compound, a peroxy compound, etc., and particularly when vulcanized with a polyol, the improved performance of the fluorine-containing elastomer of the present invention is significantly exhibited. Hereinafter, a polyol vulcanization method will be explained as an example. Fluorine-containing elastomer with acid binder, polyol compound,
Add vulcanization accelerator and filler if necessary and knead.
After extrusion molding, it is heated and vulcanized.

As the acid binder, divalent metal oxides or hydroxides, such as oxides or hydroxides of magnesium, calcium, zinc, lead, etc., are used, and the amount used is as follows:
The amount is selected in the range of 1 to 30 parts by weight, preferably 2 to 20 parts by weight, per 100 parts by weight of the elastomer. Examples of polyol compounds include hydroquinone, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-
Bis(4-hydroxyphenyl) perfluoropropane (bisphenol AF), 4,4'-dihydroxydiphenylmethane, 2,2-bis(4-hydroycyphenyl)butane, etc., per 100 parts by weight of elastomer.
It is used in a proportion of 10 parts by weight, preferably 0.6 to 5 parts by weight.

As the vulcanization accelerator, quaternary onium salt compounds, quaternary phosphonium salts, quaternary ammonium salts or iminium salts such as tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride are used. , tetrabutylammonium bromide, bis(benzyldiphenylphosphine)iminium chloride, tetrabutylphosphonium chloride, benzyltriphenylphosphonium chloride, benzyltrioctylphosphonium chloride, etc., and elastomer 100
0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight
Used in parts by weight. As fillers and reinforcing agents, for example, carbon black, silica, clay, talc, etc. are used as necessary.

When at least one peak on the low molecular weight side of the multi-peak molecular weight distribution of the fluorine-containing elastomer of the present invention is formed by polymerization using a chain transfer agent containing an iodine atom or a bromine atom, Since bromine atoms have high radical reaction activity, peroxide vulcanization using peroxides is also possible. Furthermore, since the fluorine-containing elastomer contains a low molecular weight polymer, a peroxide vulcanization method can be used simultaneously in addition to a polyol vulcanization method using a polyhydroxy compound or a polyamine vulcanization method using a polyamine compound. is possible. In this way, by using the peroxide vulcanization method in combination, it is possible to solve the problem of decreased vulcanizability that occurs with improvement in processability. This peroxide co-vulcanization is higher in the iodine type than in the bromine type.

Next, the case where peroxide vulcanization is used in combination with polyol vulcanization method or polyamine vulcanization method will be explained. In this case, in addition to the vulcanizing compounding agents used for polyol vulcanization and polyamine vulcanization, polyfunctional unsaturated compounds that are compounding agents for peroxide vulcanization, organic peroxides, and additives used as necessary. Further mix and knead. As the polyfunctional unsaturated compound, for example, triallyl cyanurate, triallyl isocyanurate, tris(diallylamine)-s-triazine, etc. are useful, and triallyl isocyanurate is particularly preferably used.

[0021] The organic peroxide is preferably one that easily generates peroxy radicals by heat, such as 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2, 5-dimethyl-2,5-di(t
Dialkyl peroxides such as -butylperoxy)hexane are preferred. Examples of additives include carbon black, silica, clay, talc, etc. as reinforcing agents, and waxes as processing aids.

[0022] The mixture of the fluorine-containing elastomer and various compounding agents is kneaded using a roll or Banbury mixer, extrusion molded, and then heated and vulcanized.

[0023]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these in any way. The properties of the fluorine-containing elastomer, the physical properties of the vulcanizate, and the processability were determined by the following methods. (1) Intrinsic viscosity: 0.0 using methyl ethyl ketone as a solvent.
A solution with a concentration of 1 g/100 ml was measured using a capillary viscometer.
Measure at 5°C. (2) Molecular weight distribution: Liquid chromatograph: LC-3A type [manufactured by Shimadzu Corporation] Column: KF-80M (2 columns)
+KF-800P (precolumn) [manufactured by Showa Denko Co., Ltd.]
Detector: ERC-7510S (manufactured by Emul Optical Co., Ltd.) Integrator: 7000A (manufactured by System Instruments) Developing solvent: Tetrahydrofuran concentration: 0.1% by weight Temperature: 35°C Standard polymer for molecular weight calibration curve: Monodisperse polystyrene Various [manufactured by Toyo Soda Co., Ltd.] [Mw/Mn=1.2 (max)
] In addition, as shown in Figure 1, in a multi-peak molecular weight distribution, if each peak overlaps and the polymer component peak does not appear clearly and has a shoulder shape, the inflection point of the chromatography may be Treated as a peak of a polymer component. (3) Mechanical properties of vulcanized product A fluorine-containing elastomer composition with a predetermined blending ratio is prepared by kneading with a roll, then put into a mold and press vulcanized, then taken out from the mold and subsequently vulcanized in an oven. A vulcanized sheet with a thickness of 2 mm was prepared. A No. 3 dumbbell-shaped test piece was punched out from this sheet, and JIS-K6301
Mechanical properties were measured using a tensile tester (manufactured by Toyo Seiki Co., Ltd.) at a tensile speed of 50 cm/min. (4) Hardness Measured using a spring type hardness tester type A according to JIS-K6301. (5) Extrusion test Extruder 10DW model manufactured by Brabender (D=1
9.1 mm, L/D = 10), using a tube die (outer diameter 9 mm, inner diameter 8 mm), screw temperature 80 ° C, head temperature 120 ° C, screw rotation speed 50.
It was carried out under the condition of rpm.

[0024] The extruded skin was visually inspected to determine the fineness of the surface texture, and was rated in five grades (from 5 to 1 in descending order of excellence). The extrusion speed was calculated from the discharge length per unit time, and the die swell was calculated from the outer diameter and thickness of the tube. (6) Roll tackiness Roll tackiness was evaluated by wrapping raw rubber or vulcanizing agent-added rubber around a roll using a 6-inch roll kneader and evaluating how easy it was to peel off.

[0025]

[Example 1-1] An autoclave with an internal volume of about 15 liters equipped with an electromagnetic induction stirrer was sufficiently purged with nitrogen gas,
5.44 kg of pure water, 1, 1, 2, deoxygenated under reduced pressure after repeating vacuum-nitrogen filling three times and replacing with nitrogen
- 1.07 kg of trichloro-1,2,2-trifluoroethane (hereinafter referred to as Freon 113) and 5.4 g of methyl cellulose (viscosity 50 cp) as a suspension stabilizer were charged, and further 0.5 g of diiodomethane was charged, and the rotation was carried out at 600 rpm.
The temperature was maintained at 50° C. while stirring at m. Then VD
F14.5% by weight, HFP79.4% by weight and TFE6
．． A mixed monomer consisting of 1% by weight is used as a charging gas,
It was prepared until it reached 15kg/cm2・G. Next, as a catalyst, diisopropyl peroxydicarbonate 20
．． 26.5 g of Freon 113 solution containing 1% by weight was injected under pressure to initiate polymerization. The pressure is 14.5 kg due to polymerization.
/cm2 ・When it decreases to G, VDF43.7% by weight,
A monomer mixture consisting of 29.6% by weight of HFP and 27.0% by weight of TFE was added as additional gas, and the pressure was increased to 15% by weight again.
kg/cm2 - Returned to G. Such operations were repeated to perform a polymerization reaction.

[0026] After 4.5 hours had passed after the start of polymerization,
42.6 g of diiodomethane was added and the pressure was increased to 14.6 g.
5 to 15.0 kg/cm2 ・Carry out the polymerization reaction by 1 more time with G.
The polymerization reaction continued for 0.6 hours, for a total of 15.1 hours. After the polymerization reaction was completed, the remaining mixed monomers were scavenged, and the resulting suspension was dehydrated using a centrifuge, thoroughly washed with water, and then dried under vacuum at 100°C to obtain about 4.4 kg of elastomer. The obtained fluorine-containing elastomer was subjected to 19F-NMR.
According to analysis, VDF unit was 43.9% by weight, H
The FP units were 30.6% by weight and the TFE units were 25.5% by weight.

[η] of this elastomer is 71ml/g
, the shape of the molecular weight distribution chart is 2 as shown in Figure 2.
It is mountain-shaped, Mn is 2.8×104, Mw/Mn is 1
It was 3.7. In addition, the peak molecular weight of the polymer component is 3
88,000, Mn was 29,000, and Mw/Mn was 6.9.

[0028]

[Example 1-2] The elastomer obtained in Example 1-1 was thoroughly kneaded using a roll kneader (roll clearance 0.5 mm), and then its molecular weight distribution was measured using GPC. The peak molecular weight of the high molecular weight component is 352,000, M
n was 31,000, Mw/Mn was 8.8, and no significant decrease in the molecular weight of the high molecular weight component was observed before and after roll kneading.

[0029]

[Example 1-3] A polyol vulcanization compounding agent was blended into the elastomer obtained in Example 1-1 using a roll kneader (roll clearance 0.5 mm), and after being left overnight, it was further kneaded. When this elastomer vulcanized compound was subjected to an extrusion test, the extrusion speed was 114 cm/min, the extrusion surface was 4.5, the inner diameter of the die well was 47, and the thickness was 38.

Similarly, a polyol vulcanization compounding agent was blended into the obtained elastomer using a roll kneader (roll clearance 2.5 mm). An extrusion test of this elastomer vulcanized compound revealed that the extrusion speed was 104.
cm/min, extrusion skin 4.5, die well inner diameter 47,
The thickness was 41 mm. No major changes were observed in the extrusion properties regardless of the difference in roll clearance or with or without kneading after standing overnight, and excellent extrusion properties were observed in all cases.

[0031]

[Example 1-4] The elastomer obtained in Example 1-1 was vulcanized by the method described above, and its mechanical properties were measured. The breaking strength was 130 kg/cm2, the elongation was 440%, and the mechanical properties were 100%.
It had a modulus of 20 kg/cm2 and a hardness of 70. Good physical properties of the vulcanizate were obtained. The composition of the vulcanizing agent and the vulcanization conditions are shown below.

[0032] Fluorine-containing elastomer
100 parts by weight Highly active magnesium 1)
3
〃 Calcium hydroxide 2)

6 Bisphenol AF

2 〃 Bis(benzyldiphenylphosphine)
1 〃
iminium chloride
SRF carbon 3)
12 〃
dimethyl sulfone
2
〃TAIC4)

0.5 〃 Perhexa25B-
405)
0.5 〃 Heat press vulcanization
Oven vulcanization at 155℃ x 80 minutes
180℃×3
hr (Note) 1) Kyowa Mag 50, manufactured by Kyowa Chemical Industry Co., Ltd. 2) Calvit, manufactured by Ohmi Chemical Industry Co., Ltd. 3) Seast S, manufactured by Asahi Carbon Co., Ltd. 4) Triallylisocyanurate 5) Japan Yushi Co., Ltd. product “Perhexa 25B-40” [
2,5-dimethyl-2,5-di(t-butylperoxy)hexane]

[0033]

[Comparative Example 1-1] An autoclave with an internal volume of about 50 liters equipped with an electromagnetic induction stirrer was sufficiently purged with nitrogen gas,
29.5 kg of pure water, 1, 1, 2, which was deoxidized under reduced pressure after being replaced with nitrogen by repeating decompression and nitrogen filling three times.
- 4.6 kg of trichloro-1,2,2-trifluoroethane (hereinafter referred to as Freon 113) and 29.5 g of methylcellulose (viscosity 50 cp) as a suspension stabilizer were charged, and the temperature was maintained at 50°C while stirring at 480 rpm. . Next, a monomer mixture consisting of 14.7% by weight of VDF, 78.6% by weight of HFP, and 6.7% by weight of TFE was charged as a charging gas until it reached 15 kg/cm2.G. Next, as a catalyst, 36.9 g of Freon 113 solution containing 20.1% by weight of diisopropyl peroxydicarbonate was introduced under pressure to initiate polymerization. When the pressure decreases to 14.5 kg/cm2 ・G due to polymerization, VDF4
3.7% by weight, HFP29.6% by weight, TFE27.0
Adding a mixed monomer consisting of % by weight as an additional gas,
The pressure was returned to 15 kg/cm2.G. Such operations were repeated to perform a polymerization reaction.

[0034] After 7.5 hours had passed after the start of polymerization,
Add 340g of diiodomethane and similarly reduce the pressure to 14.5
〜15.0kg/cm2 ・Continue the polymerization reaction with G for another 15
．． The polymerization reaction continued for 2 hours, for a total of 22.7 hours. After the polymerization reaction is completed, the remaining mixed monomers are scavenged, and the resulting suspension is dehydrated using a centrifuge and thoroughly washed with water.
Approximately 30 kg of elastomer was obtained by vacuum drying at 100°C. When the obtained fluorine-containing elastomer was analyzed by 19F-NMR, it was found that VDF units were 43.9% by weight, HFP units were 30.6% by weight, and TFE units were 25.5% by weight.

[η] of this elastomer is 122ml/
g, the shape of the molecular weight distribution chart is two peaks, and M
n was 2.9×10 4 and Mw/Mn was 17.9. In addition, the peak molecular weight of the polymer component is 124.6×104,
Mn was 29,000, and Mw/Mn was 17.9.

[0036]

[Comparative Example 1-2] The elastomer obtained in Comparative Example 1-1 was sufficiently kneaded using a roll kneader (roll clearance 0.5 mm), and then its molecular weight distribution was measured using GPC. The peak molecular weight of the high molecular weight component is 486,000, M
n was 30,000, Mw/Mn was 15.3, and a significant decrease in the molecular weight of the high molecular weight component was observed by roll kneading.

[0037]

[Comparative Example 1-3] A polyol vulcanization compounding agent was blended into the elastomer obtained in Comparative Example 1-1 using a roll kneader (roll clearance 0.5 mm), and the mixture was left to stand overnight and then further kneaded. When this elastomer vulcanized compound was subjected to an extrusion test, the extrusion speed was 149 cm/min, the extrusion surface was 4.5, the inner diameter of the die well was 27, and the thickness was 10.

Similarly, the elastomer obtained in Comparative Example 1-1 was mixed with a roll kneader (roll clearance 2.5).
A polyol vulcanization compounding agent was compounded using a polyol vulcanization compound. An extrusion test of this elastomer vulcanized compound was conducted, and the extrusion speed was 99 cm/min, the extrusion surface was 4, and the die well inner diameter was 3.
5, thickness was 27. The elastomer obtained in Comparative Example 1-1 clearly showed changes in extrusion characteristics depending on the difference in roll clearance and the presence or absence of kneading after standing overnight. In other words, an elastomer vulcanized compound with an insufficient degree of kneading had a significantly reduced extrusion speed, poor extrusion texture, and large die swell.

[0039]

[Examples 2 to 7, Comparative Example 2] Polymerization was carried out in the same manner as in Example 1-1 except for the polymerization conditions shown in Tables 1 and 2. Table 3 shows the polymer properties of the obtained elastomer, and Table 4 shows the extrusion properties, vulcanization properties, and roll tack. The composition of the vulcanizing agent and the vulcanization conditions at this time are the same as in Example 1.
-4.

[0040]

[Comparative Examples 3 and 4] Table 4 shows the results of extrusion tests, vulcanization characteristics, and roll tack measurements of commercially available fluorine-containing elastomers suitable for extrusion processing as comparative examples. The vulcanization mixture was as follows. Fluorine-containing elastomer
:100 parts by weight
(Comparative Example 3; Daiel G555)

(Comparative Example 4; Florel FT2320
)
Highly active magnesium oxide
: 3 parts by weight Calcium hydroxide
: 6 parts by weight SRF carbon
: 15 parts by weight Except for the above formulation, vulcanization was carried out under the same conditions as in Example 1-4. The elastomers of Examples 2-7 have excellent extrusion properties;
Indicates vulcanization physical properties. Furthermore, it has no roll stickiness and has very good roll processability.

Comparative Examples 2 and 3 have good extrusion properties, but roll adhesion is severe and rolling work is extremely difficult. Furthermore, Comparative Example 4 had poor extrusion texture and slow extrusion speed.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Effects of the Invention] When the fluorine-containing elastomer of the present invention is used, it has excellent extrudability, and also exhibits excellent heat resistance, oil resistance, and methanol resistance in the vulcanized product, as well as excellent mechanical properties and compression set. It is possible to obtain a vulcanizable fluorine-containing elastomer composition with little change in extrusion processability, mechanical properties, etc. due to roll kneading when blending a vulcanizing agent and the like.

[Brief explanation of the drawing]

FIG. 1 is an example of molecular weight distribution.

FIG. 2 shows the molecular weight distribution of the elastomer obtained in Example 1-1.

Claims (1)

[Claims] Claim 1: (a) a vinylidene fluoride unit, (b) a hexafluoropropylene unit, and (c) 0 to 3
Consisting of 5% by weight of tetrafluoroethylene units, and the weight ratio of (a) units to (b) units is 40:60 to 8
0:20 and its molecular weight distribution is (a) multi-peak type (b) among the molecular weight peaks, the molecular weight at the top of the highest molecular weight peak is 350,000 to 550,000 (c
) The ratio Mw/Mn of weight average molecular weight (Mw) to number average molecular weight (Mn) is 4 or more and 10 or less (d) The intrinsic viscosity number is 40 to 200 ml/g (e) Molecular weight 5
The ratio of the component ratio (M5) of 10,000 or less and the limiting viscosity number ([n]),
A fluorine-containing elastomer characterized in that M5/[n] is 0.15 to 0.70.