JP2537922B2 - Fluororubber composition for extrusion processing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fluororubber composition for extrusion processing. More specifically, the present invention relates to a fluororubber composition having an excellent balance between extrusion processability and vulcanization properties.

2. Description of the Related Art Fluorocarbon rubber is widely used as an industrial material in many fields because it is superior in heat resistance, oil resistance, solvent resistance, chemical resistance, etc. to general-purpose rubber.
Among them, in applications such as fuel hoses for automobiles, trucks, tractors, in-tank hoses, etc., extrusion speed and extrusion processability such as extruded skin and tensile properties, compression set, extraction amount for fuel oil, etc. It is desired to have excellent sulfide properties.

Conventionally, as a method of improving extrusion processability, for example, in styrene-butadiene copolymer rubber (SBR), various plasticizers such as process oil and petroleum resin are added, or liquid polybutadiene having a molecular weight of 10,000 or less or It is known to compound a butadiene-styrene copolymer and the like, and it is also known that extrusion processability can be improved also in fluorine rubber by compounding a plasticizer such as natural wax. (Japanese Patent Publication No. 52-44896, Japanese Patent Publication No. 56-25462).

However, in the case where a natural wax is mixed with fluorocarbon rubber for extrusion, the extrusion rate is improved, but the extent is small, and in addition, vulcanization physical properties such as tensile properties, impact resilience and compression set are It is unavoidable that it is remarkably deteriorated as compared with the case of not blending, and it has a drawback that it lacks the balance between extrusion processability and vulcanized physical properties.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention provides a fluororubber composition having an excellent balance between extrusion processability and vulcanized physical properties by improving the drawbacks of such a conventional fluororubber composition for extrusion processing. It was made for the purpose of providing.

Means for Solving the Problems The inventors of the present invention have conducted diligent research to develop a fluorine rubber composition having an excellent balance between extrusion processability and vulcanized physical properties, and as a result, specific copolymerized fluorine was obtained. It has been found that a rubber obtained by adding a certain amount of wax and a compounding agent for forming a vulcanized elastic body to rubber can meet the above purpose, and based on this finding, the present invention has been completed.

That is, in the present invention, the intrinsic viscosity [η] measured at a temperature of 35 ° C. in the (A) methyl ethyl ketone solvent is 70-
90 ml / g and formula 2 w / n 5 and 0.1 M ₅ / [η] 0.5 [where w is a weight average molecular weight, n is a number average molecular weight, M ₅ is a molecular weight of 50,000 or less contained in the fluororubber. Copolymerization of vinylidene fluoride unit and hexafluoropropylene unit or these units and tetrafluoroethylene unit, which satisfies the relation of polymer ratio (%), [η] is the intrinsic viscosity (ml / g)] Fluorine rubber, (B) at least one selected from Kyandelilla wax and Seraquax wax, and (C) a compounding agent for forming a vulcanized elastic body, and a content of the component (B) is (A). ) A fluororubber composition for extrusion processing, characterized in that it is in the range of 0.1 to 5 parts by weight per 100 parts by weight of the component.

 Hereinafter, the present invention will be described in detail.

The fluorine rubber used as the component (A) in the composition of the present invention is a binary copolymer composed of vinylidene fluoride (VdF) units and hexafluoropropylene (HFP) units, or these units and tetrafluoroethylene. A terpolymer consisting of (TFE) units is used. In the binary copolymer, the content ratio of the VdF unit and the HFP unit is 80:20 to 40:60 by weight, preferably 75:25.
It is desirable to be in the range of 40:60. When this content ratio deviates from the above range, the fluororubber becomes resin-like and the polymerization becomes difficult. More desirable VdF unit and H
The content ratio with the FP unit is selected in the range of 70:30 to 50:50.

On the other hand, in the terpolymer, the sum of VdF units and HFP units is 65% by weight or more, and TFE units are 35% by weight or less,
Further, it is preferable that the weight ratio of the VdF unit to the HFP unit is in the range of 80:20 to 50:50. Further, it is preferable that the content of the TFE unit is in the range of 5 to 35% by weight because the polymerization reaction is likely to proceed and a desired intrinsic viscosity is easily obtained.

The extrusion rate and the extrusion skin of the composition of the present invention are determined by the ratio M of the polymer having a molecular weight of 50,000 or less in the copolymer fluororubber M.
_It is affected by ₅ (%) and intrinsic viscosity [η], and correlates with M ₅ / [η]. That is, even if M ₅ is the same, if [η] is too large, the extrusion rate and the extrusion skin will be poor.

In the present invention, from the viewpoint of the balance between extrusion properties and vulcanized physical properties, the copolymerized fluororubber has an intrinsic viscosity [η] of 70 in a methyl ethyl ketone solvent measured at a temperature of 35 ° C.
˜90 ml / g, ratio w / n of weight average molecular weight w to number average molecular weight n is 2 to 5 and M ₅ / [η] is 0.1
Must be in the range of ~ 0.5. When the intrinsic viscosity [η] is less than 70 ml / g, the value of M ₅ / [η] is more than 0.5, or the value of w / n is more than 5, the extrusion property effect by the processing aid is obtained. May not be exhibited sufficiently, the strength of the vulcanized molded product may be low and the shape thereof may not be maintained, or the vulcanized physical properties may be insufficient. On the other hand, when the intrinsic viscosity [η] is larger than 90 ml / g, the value of M ₅ / [η] is smaller than 0.1, or the value of w / n is smaller than 2, the vulcanized physical properties are good. However, the extruded skin may deteriorate.

In the composition of the present invention, as the component (B), at least one selected from the group consisting of candelilla wax and cerax wax. The Kyandelilla wax is a wax that is secreted into the epidermis of the plant of the family Euphorbiaceae, which grows in northern Mexico, southern Texas, and southern California, and is obtained by purifying a crude wax collected from the epidermis. To be Its content is about 50% by weight
There are about 30 hydrocarbons such as Hentriacontane (C ₃₁ H ₆₄ ).
Weight percent is fatty acid ester and about 20 weight percent free fatty acids and alcohols.

On the other hand, Serratx wax is a wax contained in the secretions of Rattella serrata, which is one of the insects that grows in subtropical regions such as India and Thailand.
It is obtained by solvent extraction from a resinous material called a seed rack that has been crushed and washed with water. Its main component is a mixed ester of lacceryl alcohol, myrisilyl alcohol, ceryl alcohol, and lignocellic acid, serotic acid, laxeric acid, stearic acid, and palmitic acid.

In the present invention, each of the above-mentioned candelilla waxes and serrats waxes may be used alone, or may be used in combination, and the compatibility between these waxes and the copolymerized fluorine rubber is improved, For the purpose of enhancing the effect of improving the extrudability, a small amount of a fatty acid ester which is liquid at room temperature, such as rice bran oil, may be used in combination with the wax.

The blending amount of the wax as the component (B) is selected in the range of 0.1 to 5% by weight based on the copolymerized fluororubber as the component (A). If this amount is less than 0.1% by weight, the effect of improving the extrusion characteristics will not be sufficiently exerted, and if it exceeds 5% by weight, the vulcanized physical properties may deteriorate. Particularly preferable blending amount is 0.5 to
It is selected in the range of 3% by weight.

In the composition of the present invention, a compounding agent for forming a vulcanized elastic body is used as the component (C). As the compounding agent for forming the vulcanized elastic body, for example, a vulcanizing agent, a vulcanization aid, a vulcanization accelerator,
Examples include metal compounds and fillers.

The vulcanization of the composition of the present invention may be any of polyol vulcanization, diamine vulcanization, and peroxide vulcanization. In the polyol vulcanization, bisphenol A is used as a vulcanizing agent.
F, bisphenol, hydroquinone and the like are used, but mainly bisphenol AF is preferably used, and hexamethylenediaminecarbide is used in diamine vulcanization.
N, N′-dicinnamylidene-1,6-hexanediamine and the like are 2,5-dimethyl-2,5 in peroxide vulcanization.
-Di (t-butylperoxy) hexane is mentioned as a typical example. The amount is per 100 parts by weight of fluorocarbon rubber
0.1 to 10 parts by weight, preferably 0.6 to 5 parts by weight.

Examples of the vulcanization aid for peroxide vulcanization include triallyl isocyanurate, and its amount is 0.5 to 10 parts by weight, preferably 2 to 7 parts by weight, based on 100 parts by weight of fluororubber.

As the vulcanization accelerator used for polyol vulcanization, 8
-Benzyl-1,8-diaza-bicyclo (5.4.0) -7-undecenium chloride, bis (benzyldiphenylphosphine) iminium chloride, benzyltriphenylphosphonium chloride, and the amount thereof is fluorine rubber. Ten
It is used in a proportion of 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, per 0 parts by weight.

Examples of the metal oxide include MgO, ZnO, PbO, CaO, and BaO, and MgO is mainly used. Metal hydroxide is Ca (OH) ₂ , Mg (O
H) ₂ , Ba (OH) _{2 and the} like, and Ca (OH) ₂ is mainly used. These metal oxides and metal hydroxides are used in a proportion of 1 to 30 parts by weight per 100 parts by weight of fluororubber depending on the vulcanization method. In addition, carbon black, clay, titanium oxide, barium sulfate, etc. are used as necessary.

In the composition of the present invention, it is preferable to employ a suspension polymerization method as a method for producing the copolymerized fluororubber used as the component (A). According to this suspension polymerization method, a fluororubber having a narrow molecular weight distribution can be obtained, and the intrinsic viscosity [η] can be easily controlled by the polymerization pressure and the polymerization time. A chain transfer agent such as methanol, carbon tetrachloride or diiodomethane can be used to control the molecular weight.

Next, a preferred example of producing the copolymerized fluorine rubber by the suspension polymerization method will be described. First, an inert organic solvent in which a predetermined mixed monomer (charged monomer) is dissolved is dispersed in an aqueous medium. , Add suspension stabilizer, oil-soluble catalyst,
The temperature is maintained at 50 to 60 ° C. while mechanically stirring, and a new mixed monomer (additional monomer) is added so that the pressure becomes constant in the range of 5 to 17 kg / cm ² -G, and the polymerization proceeds. The composition of the monomer units in the resulting copolymerized fluororubber is determined by the relationship between the charged monomer composition and the additive monomer composition. The composition of the charged monomer and the composition of the added monomer are measured by gas chromatography, and the composition of the monomer unit in the copolymerized fluororubber is measured by ¹⁹ F-NMR after dissolving the rubber in acetone.

As the inert organic solvent used in this suspension polymerization method, an organic solvent having no carbon-hydrogen bond which easily causes radical chain transfer is used, and 1,1,2-trichloro-1,2,2- Trifluoroethane is preferred for both performance and economy. Methyl cellulose is preferable as the suspension stabilizer, and dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate are preferable as the oil-soluble catalyst because they have a high decomposition temperature.

EFFECTS OF THE INVENTION The fluororubber composition for extrusion of the present invention has a good balance between extrusion processability such as extrusion speed and extrusion skin properties, and vulcanization physical properties such as tensile properties, compression set, and extraction amount for fuel oil. It is excellent and especially suitable for use in fuel hoses and in-tank hoses for automobiles, trucks, tractors and the like.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

In addition, the various analytical methods and the measuring methods of physical properties in the examples were according to the following methods.

1) Analytical method The conditions for measuring the intrinsic viscosity and molecular weight distribution (M ₅ ) of fluorine rubber are as follows.

(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 tomatograph: LC-3A type (manufactured by Shimadzu Corporation) Column: KF-80M (two) + KF-800P (pre-column) (manufactured by Showa Denko KK) Detector: ERC- 7510S (manufactured by Elma Optical Co., Ltd.) Integrator: 7000A (manufactured by System Instruments) Developing solvent: Tetrahydrofuran Humidity: 0.1 wt% Temperature: 35 ° C Standard polymer for molecular weight calibration: Monodisperse polystyrene (manufactured by Toyo Soda Co., Ltd.) ( w / n = 1.2 (max)) M ₅ is calculated from the above results.

2) Physical property measurement Tensile strength, elongation, tensile stress, hardness, compression set (O-ring P-24 25% compression) are measured based on JIS-6301.

3) Extrusion test (extrusion amount, extrusion skin and die swell) Equipment: Brabender Extruder 10DW type (D
= 19.1mm L = 10D) Die: Tube type (Outer diameter 10mm, Inner diameter 8mm) Extrusion conditions: Screw temperature 60 ℃ Head temperature 100 ℃ Rotation speed 50rpm Extruded skin: Expressed in 5 stages 5: Extremely smooth 4: Smooth 3: Slightly Concavo-convex 2: Severe concavo-convex 1: Raised die swell: Expressed by the expansion rate (%) of the tube inner diameter Production example After depressurizing the autoclave reactor with a capacity of 15, water / Freon R-113 (Daikin Industries Co., Ltd.) Made) 3.5
It was put in the ratio of / 1 (volume ratio). After raising the temperature to 50 ° C, the charged monomers (VdF / HFP / TFE = 42.2 / 51.2 / 6.6mol)
% Ratio) and the pressure was adjusted to 15 kg / cm ² . Stirring was started, and 0.6 wt% of diisopropyl peroxycarbonate (hereinafter referred to as NOF, manufactured by NOF CORPORATION) was added as a polymerization catalyst (versus R-113). Then pressure 15
Addition monomer (VdF / HFP / TFE = 68/14) so that Kg / cm ²
(/ 18 mol% ratio) was adjusted to start the polymerization. 14
After polymerization for a period of time, stirring was stopped and the reactor was cooled.
The polymerization liquid extracted from the reactor after removing the monomer gas was put into a centrifugal separator to obtain a polymer (Polymer A). The polymer was washed with water and vacuum dried at 100 ° C. The intrinsic viscosity [η] of this polymer was 82 ml / g, and the molecular weight distribution w /
n was 2.2M _{5 and} 11.5%.

Examples 1 to 3 The polymers obtained in Production Examples were kneaded by rolls according to the compounding method shown in Table 1, and the extrusion characteristics and vulcanized physical properties were determined. The results are shown in Tables 2 and 3, respectively.

In addition, in Example 1, the candelilla wax was used, and in Examples 2 and 3, the ceramic wax was used.

Comparative Example 1 In Example 1, the same operation as in Example 1 was carried out without using wax, and the extrusion characteristics and the vulcanization characteristics were obtained. The results are shown in Tables 2 and 3, respectively. From this table it can be seen that the extrusion properties are significantly poorer without the wax.

Comparative Example 2 An example in which “VPA # 2” manufactured by DuPont, which is a commercially available processing aid, was added to “Viton E-45” manufactured by DuPont, which is a fluorocarbon rubber suitable for commercial extrusion. The blending ratio is shown in Table 1, its extrusion characteristics are shown in Table 2, and its vulcanized physical properties are shown in Table 3.

Comparing the product of the present invention with the case of using a commercially available product, it can be seen that the extrusion characteristics are remarkably improved and the physical properties are hardly deteriorated.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08L 91:06) C08L 91:06) (56) References JP-A-54-69584 (JP, A) ) JP-A-48-7942 (JP, A) JP-A-49-38904 (JP, A) JP-A-64-40550 (JP, A)

Claims (1)

(57) [Claims] (A) In a methyl ethyl ketone solvent (A), the intrinsic viscosity [η] measured at a temperature of 35 ° C. is 70 to 90 ml / g, and the formula 2w / n 5 and 0.1M ₅ / [η] 0.5 [however, w is the weight average molecular weight, n is the number average molecular weight, M ₅ is the proportion (%) of the polymer having a molecular weight of 50,000 or less contained in the fluororubber, and [η] is the intrinsic viscosity (ml / g)]. Satisfying the relationship, a copolymerized fluorocarbon rubber composed of vinylidene fluoride unit and hexafluoropropylene unit or these units and tetrafluoroethylene unit, (B) at least one selected from candelilla wax and serratuquax, And (C) a vulcanized elastic body-forming compounding agent, and the content of the component (B) is in the range of 0.1 to 5 parts by weight per 100 parts by weight of the component (A), for extrusion processing. Fluorocarbon rubber composition.