JPH07196881A - Fluoro-elastomer vulcanizing composition - Google Patents

Abstract

PURPOSE: To obtain a vulcanizable composition excellent in extrudability, roll processability, physical properties, and resistance to solvent extraction by compounding a fluoroelastomer with a polyol vulcanization additive or a polyamide vulcanization additive, an organic peroxide, and a polyfunctional unsaturated compound.

CONSTITUTION: There is provided an elastomer composition comprising (A) a fluoroelastomer comprising vinylidene fluoride units (i) and hexafluoropropylene units (ii) in a (i)/(ii) ratio of 40/60 to 80/20, having a limiting viscosity of 40-200 ml/g, an Mw/Mn ratio of 3-25, and a multi-peak molecular weight distribution, and containing combined bromine, (B) a polyol vulcanization additive comprising (i) a polyhydroxy aromatic compound, (ii) at least one member selected among ammonium salts, phosphonium salts, and iminium salts, and (iii) at least one member selected among divalent metal oxides or a polyamine vulcanization additive comprising (iv) a polyamine compound and (v) a divalent metal oxide, or both, (C) an organic peroxide, and (D) a polyfunctional unsaturated compound.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel vulcanizable fluorine-containing elastomer composition. More specifically, the present invention can provide a vulcanizate having good heat resistance, solvent resistance, chemical resistance, and improved mechanical properties and compression set, for example, a fuel system hose. First, sealing materials such as O-rings, seal rings, packing, gaskets, diaphragms, solenoid valves,
Used for needle valves, copier blades, contact rolls, various industrial valves, and other composite materials, and fuel hoses, valves, O- that require chemical resistance and solvent resistance. The present invention relates to a sulfuric acid-containing fluorine-containing eslatomer composition which is preferably used as a material for rings and the like.

[0002]

2. Description of the Related Art Conventional fluorine-containing elastomers have excellent heat resistance and oil resistance, so that they are used in various industrial fields such as automobiles, ships, aircrafts, hydraulic equipment, general machinery industry, pollution control, etc. It is used in O-rings, gaskets, oil seals, diaphragms, hoses, rolls, sheet materials, etc. in departments and the like. In the automobile field, it is widely used for fuel system parts, especially hoses due to its heat resistance and oil resistance. Specifically, it is a fuel hose, an in-tank hose, a filler hose or the like. Further, there is an application of a long sheet in the industrial field. These hoses and long sheets are obtained by extrusion processing. However, although these fluoroelastomers have excellent performance, they are inferior in processability to other elastomers and are not satisfactory in extrusion processability.
In order to improve the processability, a method of lowering the molecular weight is generally taken, but in the fluorine-containing elastomer whose molecular weight is lowered to increase the fluidity, not only the roll adhesion is severe but there is a problem in working, and the low molecular weight component is Since cross-linking is difficult in polyol vulcanization, important physical properties such as compression set also deteriorate.

Therefore, in order to improve the processability, processing aids such as higher fatty acid esters, silicone compounds and low molecular weight polyethylene are used (for example, Japanese Patent Publication No. 52-52).
44896). However, a small amount of processing aid does not provide sufficient effect, and when used in an amount sufficient to achieve sufficient improvement in workability, tensile strength and sealability at high temperatures are significantly reduced. Can be seen. Further, a method has been proposed in which the molecular weight distribution is changed to a multi-peak type to improve the extrudability (JP-A-2-160810). This method is very effective, but due to the relatively large amount of low molecular weight, it may stick to rolls and screws depending on the working conditions, and conventional polyol vulcanization does not sufficiently vulcanize low molecular weight components, resulting in poor physical properties. Was there. Further, various vulcanization methods such as polyamine vulcanization, polyol vulcanization, and peroxide vulcanization are known for the fluorine-containing elastomer, and the optimum vulcanization method is selected according to the application.

However, recently, applications requiring molding processability such as extrusion processability and mold flowability, use as a composite material in combination with other materials, and use under severe conditions such as in the presence of alcohol. In applications such as
It is difficult to meet the required performance with the conventional techniques of vulcanizing by conventional polyol vulcanization, polyamine vulcanization, and peroxide vulcanization. In the vulcanization method,
Polyamine vulcanization method generally has low strength of vulcanizate and poor compression set, and polyol vulcanization method is the most widely used vulcanization method at present, but the vulcanizate obtained has solvent resistance,
There is a problem of poor chemical resistance, alkali resistance, and steam resistance. Also, these two methods make it difficult to vulcanize a polymer having a low molecular weight.

On the other hand, the peroxide vulcanization method is known to solve such problems and give a vulcanized product having relatively good physical properties, but it has poor metal adhesion and
Not only is it difficult to use in combination with metal such as oil seals and valves, but it also makes it difficult to remove burrs during molding because the vulcanization does not progress extremely if exposed to air during vulcanization. It has drawbacks such as being easily polluted. Further, a polymer having a high molecular weight is difficult to be vulcanized and is inferior in strength and C-SET (compression set test).
For this reason, several methods have been attempted to solve the problems in each vulcanization method at the same time. For example, two kinds of polymers are blended and co-vulcanized with a polyol or polyamine vulcanizing agent and a peroxide vulcanizing agent. A method of doing so has been proposed (JP-A-60-72950,
62-30142 and 62-30143). These are all blends of vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene terpolymer and tetrafluoroethylene / propylene binary copolymer. Moreover, since the vulcanization reaction does not involve deiodine radical and debromine radical reactions, the vulcanization reaction is difficult to proceed. It has also been proposed to use a combination of a polyol vulcanizing compounding agent and a peroxide vulcanizing compounding agent (JP-A-62-79251). This is a blend of a bromine-containing vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene terpolymer and a tetrafluoroethylene / propylene binary copolymer. However, in this method, different polymers are blended, and the adhesion between different polymers is weak, so the physical properties are not satisfactory.

Further, in order to improve the adhesiveness between fluororubber and NBR, fluororubber and N blended with fluororubber in combination with a polyol vulcanizing agent and a peroxide vulcanizing agent.
BR laminates have been proposed (JP-A-61-2445).
45 publication). However, this laminated body does not specify fluororubber at all, and therefore, the workability and roll adhesiveness are not improved. The present inventors have already found that a composition comprising a bimodal polymer containing iodine and a mixed vulcanization of a polyol vulcanization system and a polyamine vulcanization system and a peroxide vulcanization system has excellent performance (special characteristics (Kaihei 4-209643). Based on this knowledge, the present inventors have found that the fluorine-containing elastomer of the present invention in which bromine is bonded instead of iodine is superior in extrudability as compared with the conventional fluorine-containing elastomer, and is more excellent than the iodine-containing fluorine-containing elastomer. The inventors have found that they have excellent performances such as good light stability, and completed the present invention.

[0007]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art which conventional polyamine vulcanization, polyol vulcanization, and peroxide vulcanization have, and improves mechanical properties such as strength and compression set. In addition, it is possible to give a vulcanizate with significantly improved chemical resistance, solvent resistance, solvent extraction resistance, etc. and good metal adhesion. The mold is not easily contaminated, and it is possible to vulcanize both low molecular weight components and high molecular weight components at the same time. Therefore, vulcanizable fluorine containing various excellent properties such as excellent processability, especially extrusion processability. It was made for the purpose of providing a system elastomer.

[0008]

Means for Solving the Problems As a result of intensive studies by the present inventors to develop a vulcanizable fluorinated elastomer having such excellent properties, the fluorinated elastomer having a specific bound bromine has been obtained. In addition, it was found that the above object can be achieved by adding a specific vulcanizing compounding agent and an organic peroxide, and the present invention has been completed based on this finding. That is, the present invention comprises (A) (a) vinylidene fluoride unit and (b) hexafluoropropylene unit and optionally (c) 35 wt% or less of tetrafluoroethylene unit, and (a) unit and (b) The unit weight is 40:60 to 80:20 and the intrinsic viscosity is 4
0 to 200 ml / g, the ratio Mw / Mn of weight average molecular weight (Mw) to number average molecular weight (Mn) is in the range of 3 to 25, contains bound bromine, and its molecular weight distribution is multi-peak type fluorine-containing. At least one selected from an elastomer, (B) (d) polyhydroxy aromatic compound and (v) ammonium salt, phosphonium salt and iminium salt.
(V) a polyol vulcanization compounding agent comprising at least one selected from the group consisting of (f) divalent metal oxides and divalent metal hydroxides, or (to) polyamine compound and (h) divalent To provide a fluorine-containing elastomer composition comprising a polyamine vulcanizing compounding agent comprising the metal oxide of claim 1, or both, (C) an organic peroxide, and (D) a polyfunctional unsaturated compound. Is. Hereinafter, the present invention will be described in detail.

The fluorine-containing elastomer used as the component (A) in the composition of the present invention is a vinylidene fluoride (hereinafter abbreviated as VDF) unit, a hexafluoropropylene (hereinafter abbreviated as HFP) unit and optionally tetrafluoroethylene. (Hereinafter abbreviated as TFE) units, wherein the ratio of the VDF units to the HFP units in these fluorine-containing elastomers is in the range of 40:60 to 80:20 by weight. is necessary. If the VDF unit is smaller than this, the polymerization rate is extremely slow and it is difficult to obtain a polymer having a high molecular weight. If the VDF unit is larger than this, the resulting fluoroelastomer tends to be resinous and the elasticity tends to be lowered. . Further, in the ternary fluorine-containing elastomer containing TFE, the content of TFE needs to be 35% by weight or less, preferably 5 to 25% by weight, and this content exceeds 35% by weight. The resulting fluoroelastomer tends to have reduced elasticity. Further, the preferable ratio of the VDF unit to the HFP unit is 55 in the case of the binary fluorine-containing elastomer containing no TFE unit.
Selected from 45 to 75:25, including TFE 3
In the original fluorine-containing elastomer, it is selected in the range of 45:55 to 70:30. Binary fluorine-containing elastomers are used for applications requiring low fluorine content (65% by weight), and ternary fluorine-containing elastomers for applications requiring high fluorine content (66% by weight or more), such as oil resistance and chemical resistance. It is used for automobile parts and chemical equipment parts that need to be durable.

This fluorine-containing elastomer needs to be a multi-peak type in which the molecular weight distribution is formed from two or more peaks. While the usual fluorine-containing elastomer is formed with one peak in the molecular weight distribution, by making the molecular weight distribution into a multi-peak type as in the present invention, mainly high molecular weight components have excellent physical properties, It becomes possible to provide excellent processability with a low molecular weight component. It is very difficult to simultaneously satisfy both physical properties and processability with an elastomer having one molecular weight component. Further, this fluorinated elastomer is required to have an intrinsic viscosity [η], which is an index showing the molecular weight, in the range of 40 to 200 ml / g. This [η] is 40 ml / g
If it is less than 1, the amount of low molecular weight becomes too much, the compression set resistance properties and mechanical properties decrease, and the tackiness during roll kneading increases and the mold releasability may decrease. If it exceeds 200 ml / g, the molecular weight is too high, the fluidity is lowered, and it becomes difficult to perform good extrusion molding. In addition, it becomes difficult to form a thick sheet using a roll, especially in a range where the fluorine content is high.

Further, in the fluorine-based elastomer,
It is necessary that the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 3 to 25. If this Mw / Mn exceeds 25, a relatively large amount of ultra-high molecular weight component is contained, and the die swell during extrusion molding tends to deteriorate. In addition, the effect of making the molecular weight distribution into a multi-peak type does not remarkably appear in the elastomer having Mw / Mn of less than 3. Further, as the fluorine-containing elastomer, one having a specific molecular weight distribution is preferably used. That is, regarding the multi-peak type molecular weight distribution in the present invention, an elastomer having a specific molecular weight distribution amount ratio shows excellent extrusion properties, roll processability, and further excellent vulcanized physical properties, solvent resistance, etc. Show. As the fluorine-containing elastomer, there can be mentioned the following three types. One of the preferred types is as defined in (a) to (e) below.

(A) Multi-peak type (b) Intrinsic viscosity number of 100 to 170 ml / g (c) Ratio of low molecular weight polymer having a molecular weight of 50,000 or less (M5)
(Wt%) and the intrinsic viscosity number [η] ratio M5 / [η] is 0.
25 to 0.60 (d) Weight average molecular weight (Mw) and number average molecular weight (Mn)
Ratio, Mw / Mn is 10 to 25, and (e) the ratio of low molecular weight polymer having a molecular weight of 10,000 or less (M1) is less than 15% by weight. (F) the amount of high molecular weight polymer having a molecular weight of 2 million or more. Ratio (M2
00) is 4 to 10% by weight. In such a fluorine-based elastomer, the ratio Mw / M of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
It is desirable that n is in the range of 10 to 25. This M
If w / Mn exceeds 25, a relatively large amount of ultra-high molecular weight component is contained, and the die swell during extrusion tends to be poor. Further, the elastomer having Mw / Mn of less than 10 is
Since the molecular weight distribution is narrow, the low molecular weight components are relatively small, and the extrusion moldability such as extrusion speed and extrusion surface is poor.

The intrinsic viscosity [η], which is an index showing the molecular weight, is preferably in the range of 100 to 170 ml / g. If this [η] is less than 100 ml / g, the tackiness during roll kneading may increase, and 170 ml / g
When it exceeds g, the molecular weight is too high, the fluidity is lowered, and it becomes difficult to perform good extrusion molding. Furthermore, the ratio M5 / [η] of the low molecular weight component ratio 5 (% by weight) of the component having a molecular weight of 50,000 or less and the intrinsic viscosity [η] (ml / g) is 0.25 to 0.60, preferably It is preferably in the range of 0.30 to 0.50. The M5 and [η] influence each other to influence the extrusion moldability, and when M5 becomes large, the extrusion speed and the extrusion skin tend to be improved, while when [η] becomes large, the extrusion speed and the extrusion skin become larger. Both tend to deteriorate.

Therefore, in order to have good extrusion moldability, it is desirable that the value of M5 / [η] is within the above range. If M5 / [η] is less than 0.25, extrusion becomes difficult, and if the extrusion speed or the extrusion surface is significantly deteriorated, 0.6
If it exceeds 0, the green strength tends to decrease, the green strength tends to change during extrusion molding, and the mechanical strength of the vulcanizate may decrease. Further, the low molecular weight polymer M1 having a molecular weight of 10,000 or less is 15% by weight.
It is desirable that the amount is less than 12% by weight. This M1 has a correlation with the extraction amount into the solvent when the vulcanized molded product is immersed in a solvent such as methanol, and the larger the M1 is, the larger the extraction amount into the solvent is. Therefore, if this M1 is less than 15% by weight, the extraction amount can be maintained at a level at which there is no practical problem. Further molecular weight 2
The high molecular weight polymer amount ratio M200 of, 000,000 or more is preferably in the range of 4 to 10% by weight. 4% by weight of M200
If it is less than 10% by weight, the green strength tends to be low, and the green strength tends to change during extrusion molding. Another preferred type is as defined in (a) to (d) below.

(A) Multi-peak type (b) Intrinsic viscosity number of 60 to 130 ml / g (c) Ratio of low molecular weight polymer having a molecular weight of 50,000 or less (M5)
(Wt%) and the intrinsic viscosity number [η] ratio M5 / [η] is 0.
15 to 0.60 (d) Weight average molecular weight (Mw) and number average molecular weight (Mn)
Ratio, Mw / Mn is 4 or more and less than 8 In such a fluorine-based elastomer, the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
Is preferably in the range of 4 or more and less than 8. This Mw
When / Mn is less than 4, the spread of the molecular weight is small, the low molecular weight component is small, and the extrusion moldability such as the extrusion speed and the extruded surface is poor, or the high molecular weight component is small, and the mechanical strength is reduced, If it is 8 or more, the extremely low molecular weight component increases, so that the vulcanized product has poor solvent extraction resistance. The preferable range of Mw / Mn is selected in the range of 5 to 7. The intrinsic viscosity [η], which is an index of molecular weight, is in the range of 60 to 130 ml / g, preferably 70 to 120 ml / g. If this [η] is less than 60 ml / g, the tackiness during roll kneading may be increased, and if it exceeds 130 ml / g, the molecular weight may be too large and the fluidity may be lowered, and good extrusion molding may not be possible. There is.

Further, a ratio M5 / [η] of 0.15 to 0.60, preferably a ratio (5% by weight) of low molecular weight substances having a molecular weight of 50,000 or less to an intrinsic viscosity [η] (ml / g), preferably Is 0.
It is preferably in the range of 20 to 0.50. This M5
And [η] influence each other to influence the extrusion moldability, and when M5 increases, the extrusion speed and extrusion skin tend to improve, while when [η] increases, both extrusion speed and extrusion skin deteriorate. Tend to do. Therefore, in order to have good extrusion moldability, the value of M5 / [η] is preferably in the above range. This M5 / [η] is 0.1
When it is less than 5, extrusion becomes difficult, and when the extrusion speed and the extrusion surface are significantly deteriorated, when it exceeds 0.60, the green strength decreases, the green strength tends to change during extrusion molding, and the mechanical strength of the vulcanizate may decrease. . Yet another preferred type is as defined in (a) to (e) below.

(A) Multi-peak type (b) Intrinsic viscosity number of 50 to 150 ml / g (c) Low molecular weight polymer having a molecular weight of 50,000 or less (M5)
(Wt%) and the intrinsic viscosity number [η] ratio M5 / [η] is 0.
30 to 0.70 (d) Weight average molecular weight (Mw) and number average molecular weight (Mn)
Ratio of Mw / Mn is 8 to 20. (e) A high molecular weight polymer having a molecular weight of 2,000,000 or more (M2
00) is less than 4% by weight. In such a fluorine-based elastomer, the ratio Mw / M of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
It is desirable that n is in the range of 8 to 20. This Mw
If / Mn exceeds 20, a relatively large amount of ultra-high molecular weight component is contained, and the die swell during extrusion tends to become poor. Further, an elastomer having Mw / Mn of less than 8 has a narrow molecular weight distribution and thus has a relatively small amount of low molecular weight components, and thus has poor extrusion moldability such as extrusion speed and extrusion skin. Also, the intrinsic viscosity [η], which is an index showing the molecular weight, is 50 to 150 ml / g.
It is desirable to be in the range of. This [η] is 50 ml /
If it is less than g, the tackiness at the time of roll kneading may be increased, and if it exceeds 150 ml / g, the molecular weight is too high and the fluidity is lowered, making it difficult to perform good extrusion molding.

Furthermore, the ratio of low-molecular weight M5 (% by weight) of components having a molecular weight of 50,000 or less and the intrinsic viscosity [η] (ml / g)
It is desirable that the ratio M5 / [η] of the above is in the range of 0.30 to 0.70, preferably 0.25 to 0.65. The M5 and [η] influence each other to influence the extrusion moldability, and when M5 becomes large, the extrusion speed and the extrusion skin tend to be improved, while when [η] becomes large, the extrusion speed and the extrusion skin become larger. Both tend to deteriorate. Therefore,
In order to have good extrusion moldability, the value of M5 / [η] is preferably in the above range. If M5 / [η] is less than 0.30, extrusion becomes difficult, and the extrusion speed and the extrusion surface are significantly deteriorated. If it exceeds 0.70, the green strength is lowered, and the vulcanization tends to occur during extrusion molding. The mechanical strength of the product may be reduced. Further, the low molecular weight polymer M200 having a molecular weight of 2,000,000 or less is preferably less than 4% by weight. If the M200 exceeds 4% by weight, the die swell and the extruded skin tend to deteriorate.

Since the above-mentioned three types of polymers have their respective characteristics, they can be properly used at different times. For example, Mw /
Elastomers having Mn of 4 or more and less than 8 have a very low molecular weight and therefore can be easily kneaded without sticking even when the roll surface is relatively hot during kneading. Also, Mw / Mn is 10 to 25 and M200 is 4 to 1.
The 0% elastomer has a large amount of high molecular weight components and low molecular weight components, and therefore has good extrusion processability without deteriorating the physical properties. In addition, Mw / Mn is 8 to 20 and M20
Elastomers having 0 of less than 4% by weight have relatively low molecular weight components and therefore have extremely good extrusion processability, and good extrusion characteristics can be obtained even at low extrusion temperatures. For processing machines such as extrusion molding machines, the optimal elastomer for extrusion varies depending on the extrusion temperature, screw, die size and design. It is necessary to select a polymer having a different molecular weight distribution depending on the equipment used and its operating conditions.

The fluorine-based elastomer used as the component (A) in the composition of the present invention must have bromine bonded in its molecular chain. This bromine is desorbed by an organic peroxide during vulcanization to form a radical in the polymer chain, and this radical serves as a crosslinking point. In particular, low molecular weight components are difficult to vulcanize by polyol vulcanization, so extremely good physical properties can be obtained by combining bromine with a low molecular weight component and vulcanizing it in combination with a polyol, and from the vulcanizates The molecular weight component is not extracted with a solvent or the like. As a method of introducing bromine into a polymer chain, a method of polymerizing in the presence of a bromine compound (Japanese Patent Publication No.
No. 42302), and a method of copolymerizing a monomer containing bromine (Japanese Patent Publication No. 53-4115).

In the method of polymerizing in the presence of a bromine compound, an alkyl bromide compound and its perfluoro compound are preferably used as the bromine compound. For example, CF ₂ Br ₂ , CF ₂ BrCF ₂ Br, CF ₃ CFBr
CF ₂ Br, CF ₃ Br, CH ₃ Br, CH ₂ Br ₂ and the like. As the bromine-containing monomer used in the method of copolymerizing the bromine-containing monomer, a bromine-containing olefin is preferably used. For example, bromotrifluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene-1, vinyl bromide, bromodifluoroethylene and the like. The bromine content in the polymer is usually selected in the range of 0.01 to 5% by weight, preferably 0.1 to 2.5% by weight. If it is less than 0.01% by weight, the crosslinking becomes insufficient, and 5
When it exceeds the weight%, it becomes difficult to obtain an elastic body.

The fluoroelastomer in the present invention can be polymerized by various known polymerization methods such as suspension polymerization and emulsion polymerization. The multi-peak type fluoroelastomer referred to in the present invention can be produced, for example, by blending a high molecular weight polymer and a low molecular weight polymer, which are separately produced, and a chain transfer agent is added during the polymerization. Then, the polymerization can be continued. Among them, the method of additionally adding a chain transfer agent during the polymerization by the suspension polymerization method is preferable because a polymer having a multi-peak type molecular weight distribution having a relatively sharp peak can be obtained. As the chain transfer agent used in this case, the bromine compounds exemplified above can be used. Explaining a preferred example of this suspension polymerization method, first, an inert organic solvent containing a predetermined mixed monomer (charged monomer) was dispersed in an aqueous medium,
Further, a suspension stabilizer and an oil-soluble catalyst are added, and if necessary, the chain transfer agent is added, and the temperature is maintained at 50 to 60 ° C. with mechanical stirring, and the pressure is preferably 5 to 17 kg.
The above-mentioned new mixed monomer (additional monomer) is added so as to be constant within the range of / cm ² · G, and the polymerization is advanced. The composition of the monomer units in the resulting fluoroelastomer is determined by the relationship between the charged monomer composition and the added monomer composition. The monomer composition is gas chromatograph,
The composition of the monomer unit in the elastomer is measured by F-NMR. Further, the molecular weight distribution is adjusted and bromine is introduced by adding the chain transfer agent during the polymerization.

As the inert organic solvent, 1,1,2-trichloro-1,2,2-trifluoroethane or the like is used. Methylcellulose or the like is used as the suspension stabilizer. As the oil-soluble catalyst, dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate are preferable because they have a high decomposition temperature. As the component (B) of the present invention, a vulcanizing agent comprising at least one of a polyol vulcanizing compounding agent and a polyamine vulcanizing compounding agent is used. The polyol vulcanization compounding agent is (d) a polyhydroxy aromatic compound and (e) at least one selected from ammonium salts, phosphonium salts and iminium salts,
(F) At least one selected from divalent metal oxides and divalent metal hydroxides.

Examples of the polyhydroxy aromatic compound (d) include bisphenol AF, bisphenol A, bisphenol S, dihydroxybenzophenone, hydroquinone, 2,4,6-tricapto-S-triazine,
4,4'-thiodiphenol and metal salts thereof and the like can be mentioned. The mixing ratio of the cross-linking agent in the fluoroelastomer vulcanizing composition of the present invention is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the component (A). is there. As the ammonium salt, phosphonium salt and iminium salt of (e), for example, the following are used. Specific examples thereof include tetramethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, benzyltriphenylphosphonium chloride, bis (benzyldiphenylphosphine) iminium chloride and DBU salt. The compounding ratio of the vulcanization accelerator in the fluorinated elastomer vulcanization composition of the present invention is usually 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight, relative to 100 parts by weight of the component (a). It is a department. Examples of the divalent metal hydroxides and oxides of (f) include hydroxides and oxides of magnesium, calcium, zinc, lead and the like. The amount of divalent metal hydroxide and divalent metal oxide is usually 1 to 10 parts by weight, and 2 to 20 parts by weight are added together for 100 parts by weight of the component (A).

If desired, various vulcanization accelerator activators may be added to accelerate vulcanization. Typical examples of the vulcanization accelerator include sulfone compounds such as dimethyl sulfone and dichlorodiphenyl sulfone. The polyamine vulcanizing compound is
(G) A polyamine compound and (h) a divalent metal oxide. Examples of the (g) polyamine compound include hexamethylenediaminecarbamate, N, N'-dicinnamylidene-1,6-hexamethylenediamine, and 4,4'-bis (aminocyclohexyl) methanecarbamate. The amount of addition is usually 10
0.1 to 10 parts by weight, preferably 0.
5 to 5 parts by weight. Examples of the divalent oxide of (h) include magnesium,
Examples thereof include oxides such as calcium, zinc and lead. The divalent metal oxide is usually added to 100 parts by weight of the component (A),
Each is 1 to 30 parts by weight, preferably 2 to 20 parts by weight.

Examples of the organic peroxide which is the component (C) of the present invention include the following. As the organic peroxide, those which easily generate a peroxy radical by heat are preferable, for example, 2,5-dimethyl-2,5-di (t-
Butylperoxy) hexyne-3,2,5-dimethyl-
Dialkyl peroxides such as 2,5-di (t-butylperoxy) hexane and dicumyl peroxide are preferable. The amount of addition is selected depending on the amount of active oxygen and the decomposition temperature, but is usually selected in the range of 0.05 to 10 parts by weight, preferably 0.05 to 5 parts by weight, per 100 parts by weight of the elastomer. As the polyfunctional unsaturated compound which is the component (D) of the present invention, for example, triallyl isocyanurate, triallyl sialate and the like are suitable.
The compounding amount is 0.01 per 100 parts by weight of the elastomer.
It is selected in the range of 10 to 10 parts by weight, preferably 0.1 to 5 parts by weight.

Further, in the fluoroelastomer vulcanizing composition of the present invention, if necessary, other components such as carbon black, austin black, graphite, silica clay, diatomaceous earth, talc, wollastonite,
Calcium carbonate, calcium silicate, calcium fluoride,
Barium sulfate, sulfone compound, phosphate ester, aliphatic amine, higher fatty acid ester, fatty acid calcium, fatty acid amide, low molecular weight polyethylene, silicone oil, silicone grease, metal soap, stearic acid, calcium stearate, magnesium stearate, aluminum stearate, Fillers such as zinc stearate, titanium white and red iron oxide, processing aids, plasticizers, colorants and the like can be added. The fluorinated elastomer vulcanized composition thus obtained may be vulcanized and molded by, for example, sufficiently kneading with an open kneading roll or a closed kneading roll (Banbury mixer, pressure kneader, etc.), and then vulcanizing. A method may be mentioned in which the composition is cut into a ribbon, molded by extrusion molding, and then vulcanized. As a vulcanization method, there are a method of steam vulcanization and a method of vulcanization with a continuous vulcanization device. As other vulcanizing means, a method of primary vulcanization by compression molding and then secondary vulcanization, or a method such as ketones such as methyl ethyl ketone and acetone, ethers such as ethyl ether and tetrahydrofuran, etc.
A solution or dispersion containing one or more kinds of media as a medium is prepared, and then the surface of paper, fiber, film, sheet, plate, tube, pipe, tank, large container or other molded article is coated and vulcanized. A method etc. can also be used. It is also possible to make a multilayer molded product such as a multilayer sheet or a multilayer hose by forming a multilayer with another type of rubber, for example, NBR, acrylic rubber, EP rubber or the like.

The fluorine-containing elastomer used in the present invention has bound bromine, and this bromine is eliminated by an organic peroxide during vulcanization. Then, a plurality of molecular chains are covalently bonded to each other through a polyfunctional unsaturated compound at the leaving portion to form a crosslinked structure. Further, by introducing bromine into the low molecular weight component, it is possible to vulcanize the low molecular weight component which is difficult to vulcanize the polyol with peroxide.
Therefore, when used in combination with a polyol vulcanization compounding agent or a polyamine vulcanization compounding agent, it is sufficiently vulcanized from a low molecular weight component to a high molecular weight component, and has high strength and high elongation, and exhibits excellent physical properties. Is obtained. Further, since the vulcanization density is increased, the compression set is improved. Further, since extremely low molecular weight components that cannot be vulcanized by polyol vulcanization or polyamine vulcanization can be vulcanized, the vulcanized product has greatly improved gasoline permeation resistance and gasoline extraction resistance.

In conventional polyol and polyamine vulcanization,
Since the cross-linking points are bonded by carbon and hydrogen or carbon and nitrogen,
Although it is inferior in chemical resistance, according to the present invention, the chemical resistance is also improved because it is reinforced by the network chain formed by carbon-carbon bonds by peroxide vulcanization. Further, in the conventional peroxide vulcanization, the vulcanization reaction is difficult to proceed when it is exposed to air, and therefore the burrs that have been exposed to air are insufficiently vulcanized and are difficult to remove, and the burrs adhere to the mold and are contaminated. On the other hand, in the present invention, the portion exposed to air is sufficiently vulcanized with the polyol vulcanizing agent or the polyamine vulcanizing agent, so that burrs are easily removed and the mold is not contaminated. In the present invention, by using an elastomer having a certain limited molecular weight distribution, it is possible to obtain an elastomer compound having extremely excellent processability, particularly extrusion processability, and excellent vulcanization physical properties. That is, it is composed of two or more peaks of a low molecular weight component and a high molecular weight component, and by using an elastomer containing bromine in at least the low molecular weight component, the low molecular weight component has excellent processability, and the low molecular weight component is bromine. It has excellent vulcanization properties because it is vulcanized by. Also, low molecular weight components are not extracted when immersed in a solvent or fuel oil. In recent years, as typified by fuel hoses and parts around the engine of automobiles,
Heat resistance, solvent resistance, and fuel oil resistance are required, and the number of parts that are difficult to process is increasing because they are made by extrusion molding or injection molding and have complicated shapes. Further, it is required that the extract content when immersed in fuel oil is low. The composition of the present invention can be used most preferably because it can satisfy such requirements.

[0030]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The physical properties and processability of the fluoroelastomer were determined by the methods described below. (1) Intrinsic viscosity number: A 0.1 g / 100 ml concentration solution using methyl ethyl ketone as a solvent is measured at 35 ° C. using a capillary viscometer. (2) Molecular weight distribution: Liquid chromatograph LC-3A type [manufactured by Shimadzu Corporation] Column KF80M (two) + KF800P [manufactured by Showa Denko KK] Detector ERC-7510S [manufactured by Elma Optical Co., Ltd.] Solvent Tetrahydrofuran concentration 0.1% by weight Temperature 35 ° C. (3) Presence or absence of bromine in polymer: X-ray fluorescence method (4) Hardness of vulcanized product [JIS-A], 100% tensile stress, tensile strength, elongation Was measured according to JIS-K6301.

(5) Roll Adhesion: Using an 8-inch roll kneader, raw rubber was wrapped around a roll and kneaded with a compounding agent such as a vulcanizing agent and carbon, and then evaluated for the ease of peeling from the roll. (6) Extrusion test: Brabender Extruder 1
By using 0W type (D = 19.1 mm, L / D = 10),
A tube die (outer diameter 10 mm, inner diameter 8 mm) was used under the conditions of a screw temperature of 60 ° C., a head temperature of 100 ° C. and a screw rotation speed of 50 rpm. Extruded skin can be visually observed in 5 stages (5
To 1). The extrusion rate was calculated from the discharge length per unit time. The screw adhesion amount was judged from the amount of rubber attached to the screw after the screw was extracted after extruding 500 g.

(7) Methanol extractability: 50 g of vulcanized rubber
Is cut into 5 mm squares, immersed in methanol at 60 ° C. for 5 days, the immersion liquid is concentrated to dryness, and the weight of the precipitate is measured.

Reference Example 1 An autoclave with an internal volume of about 50 liters equipped with an electromagnetic induction stirrer was sufficiently scavenged with nitrogen gas, and depressurization-filling with nitrogen was repeated 3 times to replace nitrogen, and then deoxygenated under reduced pressure. 23.6 kg of purified water, 1,1,2-trichloro-1,
Charge 2,96-liter of 2,2-trifluoroethane (hereinafter referred to as Freon 113) and 23.6 g of methylcellulose (viscosity 50 cp) as a suspension stabilizer,
The temperature was kept at 50 ° C. with stirring at pm. Then 14.5% by weight of VDF, 79.1% by weight of HFP and TF
A mixed monomer composed of E6.4 wt% was charged as a charging gas until the amount became 15 kg / cm ² · G. Next, diisopropyl peroxydicarbonate 2 as a catalyst
57.0 g of a Freon 113 solution containing 0.1% by weight was injected under pressure to initiate polymerization. Pressure is 14.5k due to polymerization
When it decreases to g / cm ² · G, VDF 43.5% by weight,
A mixed monomer composed of 29.5% by weight of HFP and 27.0% by weight of TFE was added as an additional gas, and the pressure was adjusted to 15 again.
It was returned to kg / cm ² · G. This operation was repeated to carry out the polymerization reaction.

After 6.3 hours from the start of the polymerization,
Dibromotetrafluoroethane (CF ₂ BrCF ₂ Br)
57.0 g of Freon 113 solution containing 226 g and 20.1% by weight of diisopropyl peroxydicarbonate
Is added, and the pressure is similarly 14.5 to 15 kg / cm ² · G
The polymerization reaction was continued for another 15.8 hours and the total was 22.1.
The polymerization reaction was carried out for a time. After the completion of the polymerization reaction, the remaining mixed monomer was scavenged, the obtained suspension was dehydrated by a centrifuge, thoroughly washed with water, and then vacuum dried at 100 ° C. to obtain about 25.4 kg of an elastomer. When the obtained fluorine-based elastomer was analyzed by F-NMR, it was found that the VDF unit was 44% by weight, the HFP unit was 30% by weight, and the TFE unit was 26% by weight. [Η] of this elastomer is 119 ml / g,
The chart of the molecular weight distribution has two peaks, and Mn is 2.
It was 5 × 10 ⁴ , and Mw / Mn was 18.4. Also, M
5 / [η] was 0.49, M1 was 8.8%, and M200 was 6.8%. Further, bromine was detected in the elastomer.

Reference Example 2 Further, when a commercially available fluorine-containing elastomer for extrusion (Florel FT2320 manufactured by 3M Co.) was purchased and analyzed by F-NMR, VDF unit was 44% by weight, HFP unit was 30% by weight, and TFE unit was 26% by weight. %Met. The [η] of this elastomer was 65 ml / g, the shape of the chart of the molecular weight distribution was one peak, Mn was 5.3 × 10 ⁴ , and Mw / Mn was 4.6. Also, M5 / [η] is 0.36, M1
Was 2.7%. Furthermore, bromine was not detected in the elastomer. Further, a polyol vulcanization compounding agent was internally added to this elastomer in advance.

Using the elastomers of Reference Examples 1 and 2, Table 1
Various physical properties and characteristics were measured by kneading and vulcanizing with the compounding composition shown in. The results are shown in Table 1. It can be seen that the composition of the present invention exhibits excellent physical properties, and also exhibits excellent workability in terms of roll processability and sticking of the screw during extrusion without sticking. Further, it can be seen that even with a solvent typified by methanol which easily corrodes a fluororubber, the fluoroelastomer vulcanizing composition of the present invention has a low extraction amount although it has many low-molecular weight components. In addition, the following compounds were used.

SRF carbon: "Cast S" manufactured by Tokai Carbon Co., Ltd.-Ca (OH) ₂ : "Calbit" manufactured by Omi Chemical Co., Ltd.-MgO (# 150): "Kyowamag 150" manufactured by Kyowa Chemical Industry Co., Ltd. AC-30: Polyol vulcanizing agent manufactured by Asahi Kasei Co., Ltd.-AC-40: Polyol vulcanization accelerator manufactured by Asahi Kasei Co., Ltd.-Perhexa 25B40: Organic peroxide manufactured by NOF Corporation TAIC: manufactured by Nippon Kasei Co., Ltd. "Tyke" (triallyl isocyanurate)

[0038]

[Table 1]

[0039]

INDUSTRIAL APPLICABILITY As described above, the fluorinated elastomer vulcanized composition of the present invention has excellent extrusion processability and roll processability as well as excellent physical properties and solvent extraction resistance.

Claims (2)

[Claims] 1. A composition comprising (A) (a) vinylidene fluoride unit and (b) hexafluoropropylene unit, and the weight of (a) unit and (b) unit is 40:60 to 8.
0:20, intrinsic viscosity 40 to 200 ml /
g, a ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is in the range of 3 to 25, contains bound bromine, and its molecular weight distribution is a multi-peak type fluorine-containing elastomer, (B) (d) polyhydroxy aromatic compound and at least one selected from (v) ammonium salt, phosphonium salt and iminium salt, (f) divalent metal oxide and divalent metal hydroxide A polyol vulcanization compounding agent comprising at least one selected from the group of compounds, or a polyamine vulcanizing compounding agent comprising (to) a polyamine compound and (h) a divalent metal oxide, or both, ) A fluorine-containing elastomer composition comprising an organic peroxide and (D) a polyfunctional unsaturated compound. 2. A) (a) vinylidene fluoride unit, (b) hexafluoropropylene unit and (c) 3
Consisting of less than 5% by weight of tetrafluoroethylene units,
The weight of the (a) unit and the (b) unit is 40:60 to 80:20, and the intrinsic viscosity is 40 to 200 ml /
g, a ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is in the range of 3 to 25, contains bound bromine, and its molecular weight distribution is a multi-peak type fluorine-containing elastomer, B) (d) Polyhydroxy aromatic compound and at least one selected from (v) ammonium salt, phosphonium salt and iminium salt, (f) divalent metal oxide and divalent metal hydroxide A polyol vulcanization compounding agent comprising at least one selected from the above, or a polyamine vulcanization compounding agent comprising (to) a polyamine compound and (h) a divalent metal oxide, or both, (C) A fluorine-containing elastomer composition comprising an organic peroxide and (D) a polyfunctional unsaturated compound.