JP2010095578A - Fluororubber composition, cross-linked fluororubber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a colorable low temperature type fluororubber composition excellent in impact embrittlement temperature and tensile strength, to provide a cross-linked fluororubber, and to provide a method for producing the same. <P>SOLUTION: There is provided the colorable fluororubber composition characterized by comprising at least a fluororubber comprising a peroxide-vulcanizable fluoropolymer, a peroxide-based cross-linking agent, and calcium carbonate, wherein the calcium carbonate is compounded in an amount of 5 to 30 pts.wt. per 100 pts.wt. of the fluoropolymer. The peroxide-vulcanizable fluoropolymer is preferably vinylidene fluoride-perfluoro(methyl vinyl ether)-tetrafluoroethylene ternary fluorocopolymer having a characteristic comprising a TR-10 value of -40°C to -25°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a colorable fluororubber composition having low temperature and heat resistance, a cross-linked fluororubber and a method for producing the same, and in particular, a low temperature fluoropolymer composition having excellent impact embrittlement temperature and tensile strength and the production thereof. Regarding the method.

  Fluororubber is very excellent in oil resistance and heat resistance, and is used in a wide range of applications such as O-rings used in combustion systems such as automobiles and gaskets for intake manifolds. .

  Viton GLT (trade name) series manufactured by DuPont, which is a low temperature type fluororubber, is attracting attention as a material excellent in fuel oil resistance and low temperature resistance. These fluororubbers are usually black fluororubbers containing carbon (Patent Document 1). Recently, demands for colored fluororubbers tend to increase due to market needs such as identification.

  For coloring, carbon cannot be blended, but unless carbon is blended, there is a problem that heat resistance and reinforcing properties are lowered.

  Patent Document 2 describes a low-temperature type fluororubber composition in which low-temperature type fluororubber is colored by blending fired talc and red pepper, and the result of the TR test (low-temperature elastic recovery test) is the same as that of carbon blending. is there. However, such a composition has a deteriorated (higher) impact embrittlement temperature and a lower tensile strength than a carbon compounded rubber, so that the gasket for the intake manifold is reduced. When used as, there is a possibility that the sealing performance at low temperature is not sufficient.

In addition, it is conceivable to mix silica, but it is not preferable to add silica because it is more expensive than carbon in terms of cost.
Japanese Patent Laid-Open No. 10-139970 International Publication No. 2008/038555

  Accordingly, an object of the present invention is to provide a colorable low-temperature type fluororubber composition having excellent impact embrittlement temperature and tensile strength, a fluororubber crosslinked product, and a method for producing the same.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
Fluorine rubber made of a fluoropolymer capable of peroxide vulcanization, a peroxide-based cross-linking agent, and calcium carbonate, and containing 5 to 30 parts by weight of the calcium carbonate per 100 parts by weight of the fluoropolymer A fluororubber composition characterized in that it is possible.

(Claim 2)
The peroxide vulcanizable fluoropolymer is a vinylidene fluoride-perfluoro (methyl vinyl ether) -tetrafluoroethylene ternary fluoropolymer having a TR-10 value of -40 ° C to -25 ° C. 2. The fluororubber composition according to claim 1, wherein

(Claim 3)
3. The fluororubber composition according to claim 1, wherein 10 to 20 parts by weight of calcium carbonate is blended per 100 parts by weight of the fluoropolymer.

(Claim 4)
The fluororubber composition according to claim 1, 2 or 3, wherein the blending amount of carbon black is 0.5 parts by weight or less per 100 parts by weight of the fluoropolymer.

(Claim 5)
A method for producing a crosslinked fluororubber, wherein the fluororubber composition according to any one of claims 1 to 4 is heat-treated after kneading.

(Claim 6)
The method for producing a cross-linked fluororubber according to claim 5, wherein the cross-linked fluororubber has an impact embrittlement temperature of -30 ° C or lower and a tensile strength of 15 MPa or higher.

(Claim 7)
A cross-linked fluororubber obtained by the method for producing a cross-linked fluororubber according to claim 5 or 6 is used for a gasket for an intake manifold.

  ADVANTAGE OF THE INVENTION According to this invention, the low temperature type fluororubber composition which can be colored which was excellent in impact embrittlement temperature and tensile strength, a fluororubber crosslinked body, and its manufacturing method can be provided.

  Embodiments of the present invention will be described below.

[Fluoro rubber composition]
The fluororubber composition of the present invention contains at least fluororubber composed of a fluoropolymer capable of peroxide vulcanization, a peroxide-based crosslinking agent, and calcium carbonate.

<Fluorine rubber>
As the fluoropolymer capable of peroxide vulcanization used in fluororubber, a fluorinated olefin terpolymer can be used.

  Specific examples of the fluorinated olefin include vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoroacrylic acid ester, and acrylic acid. Examples include perfluoroalkyl, perfluoromethyl vinyl ether, and perfluoropropyl vinyl ether.

  As the ternary fluoropolymer, preferably vinylidene fluoride-perfluoro (methyl vinyl ether) -tetrafluoroethylene terpolymer (abbreviation: VdF / TFE / PMVE system), vinylidene fluoride-hexafluoropropylene-tetra Fluoroethylene terpolymer (abbreviation: VdF / HFP / TFE system) and the like.

  These polymers can be obtained by solution polymerization, suspension polymerization or emulsion polymerization by a conventionally known method, and can be obtained as a commercial product, and are of a low temperature type. Among them, for example, GLT type (manufactured by DuPont) ( VdF / HFP / TFE system).

  In the present invention, the low temperature type means a TR-10 value having a characteristic of −40 ° C. to −25 ° C.

  Here, the TR-10 value is based on JIS K 6261, and after the rotary sliding seal sample is stretched 50%, the temperature is lowered, and the glass transition point (Tg) or less is vitrified by a low temperature elastic recovery tester. The temperature is gradually raised to alleviate the distortion of the sample, and the temperature recovered 10% with respect to the initial elongation is set to the TR-10 value.

  As the fluororubber used in the present invention, for example, a fluororubber having iodine and / or bromine in the molecule can be used. When these fluororubbers are generally vulcanized (crosslinked) with an organic peroxide, it is preferable to use a polyfunctional unsaturated compound typified by triallyl isocyanurate together with the organic peroxide.

  In the present invention, the fluororubber satisfying the above-mentioned low temperature type performance can be appropriately selected.

<Crosslinking agent>
As the peroxide-based crosslinking agent used as the crosslinking agent, an organic peroxide crosslinking agent can be preferably used. Examples of the organic peroxide crosslinking agent include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tertiary butyl peroxide, dicumyl peroxide, tertiary butyl cumyl peroxide, 1,1-di (tertiary butyl peroxy) -3 , 3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-di (tert-butylperoxyisopropyl) benzene, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, n Such as butyl-4,4-di (t-butylperoxy) valerate is used. These crosslinking agents may be used alone or in combination of two or more.

  In the present invention, commercially available products (for example, “Perhexa 25B-40” manufactured by NOF Corporation) can be used as they are.

  Moreover, you may use the commercially available masterbatch containing raw material rubber and a crosslinking agent as a peroxide crosslinking agent.

  The content of the peroxide-based crosslinking agent is preferably in the range of 0.5 to 5 parts by weight, more preferably in the range of 1 to 3 parts by weight as an active ingredient per 100 parts by weight of the fluoropolymer.

<Crosslinking accelerator>
Examples of the crosslinking accelerator (auxiliary) that can be used in the peroxide-based crosslinking system include metal oxides typified by zinc oxide, triallyl isocyanurate, and the like, and other fatty acids typified by stearic acid. It is done.

  The content of the crosslinking accelerator is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 0.2 to 5 parts by weight per 100 parts by weight of the fluororubber polymer component.

<Calcium carbonate>
Calcium carbonate can be selected as appropriate, but since the adhesion to the kneader is reduced, the surface is preferably treated with a fatty acid, and the average particle size is 10 to 10 to give appropriate reinforcement. The thing of 200 nm is preferable.

  Examples of calcium carbonate that can be preferably used in the present invention include “Shiraka Hana CC” (average particle size: 50 nm) manufactured by Shiraishi Calcium Co., Ltd.

  Here, the average particle diameter of calcium carbonate is obtained by actually measuring individual particle diameters from a scanning electron micrograph of calcium carbonate and obtaining the number average value thereof.

  The content of calcium carbonate is in the range of 5 to 30 parts by weight, preferably 10 to 20 parts by weight, per 100 parts by weight of the fluoropolymer.

  If the blending amount is less than this, strength cannot be obtained, and if the blending amount is more than this, not only the hardness becomes too high but also the brittle temperature is deteriorated.

<Colorant>
In the present invention, “colorable” means that coloring is possible by adding a colorant other than black, and carbon black is not substantially added.

  The term “substantially not blended” here is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, per 100 parts by weight of the fluoropolymer.

  In the present invention, the colorant that can be used in the color formulation includes brown rice, zinc oxide, titanium oxide, aniline black, cadmium yellow, yellow iron oxide, titanium yellow, insoluble disazo yellow, condensed azo yellow, isoindolinone yellow, Benzimidazolone yellow, insoluble disazo orange, benzimidazolone orange, perinone orange, cadmium red, monoazo lake red, insoluble monoazo red, benzimidazolone red, condensed azo red, quinacridone red, perylene red, anthraquinonyl red, quinacridone bio Red, dioxazine bio red, cobalt blue, ultramarine blue, phthalocyanine blue, insoluble disazo blue, indanthrone blue, titanium cobalt green, chlorinated phthalose Nin green, brominated phthalocyanine green, benzimidazolone brown, aluminum, and the like.

  In the present invention, the content of the colorant is preferably 1 to 10 parts by weight, more preferably 3 to 8 parts by weight per 100 parts by weight of the fluoropolymer.

<Other ingredients>
In the present invention, in addition to the above components, as rubber compounding agents, for example, hydrotalcite (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ ), magnesium carbonate, aluminum hydroxide, magnesium hydroxide, aluminum silicate, silicic acid Fillers such as magnesium, calcium silicate, potassium titanate, magnesium oxide, titanium oxide, barium sulfate, aluminum borate, glass fiber, aramid fiber; processing aids such as wax and metal soap; calcium hydroxide, zinc oxide, etc. A compounding agent generally used in the rubber industry such as an acid acceptor, an anti-aging agent, a thermoplastic resin, and the like can be added as necessary as long as the effects of the present invention are not impaired.

  As a method for preparing the fluororubber composition, for example, a predetermined amount of each of the above components is kneaded with a closed kneader such as an intermix, kneader, banbury mixer, or a general kneader for rubber such as an open roll. Alternatively, there is a method in which each component is dissolved with a solvent or the like and dispersed with a stirrer or the like.

[Method for producing crosslinked fluororubber]
The fluororubber composition obtained as described above is usually heated at a temperature of 140 ° C. to 230 ° C. for about 1 to 120 minutes using an injection molding machine, a compression molding machine, a vulcanizing press machine, an oven or the like ( By primary vulcanization, crosslinking (vulcanization) molding can be performed.

  The primary vulcanization is a process of crosslinking to such an extent that the shape can be maintained in order to form a certain shape (preliminary molding). In a complicated shape, the vulcanization is preferably performed by a mold, and even in an oven such as air heating. Primary vulcanization is possible.

  In the present invention, after the primary vulcanization, a secondary vulcanization heat treatment may be performed as necessary. When performing secondary vulcanization, it is preferable to heat-treat in the temperature range of 200 to 300 ° C. for 1 to 20 hours.

[Use of crosslinked fluororubber]
The fluororubber crosslinked product obtained as described above can be colored and has an impact embrittlement temperature and a tensile strength substantially equivalent to those of carbon, and can be suitably used as a gasket for intake manifolds.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

Example 1
<Composition ingredients and amount>
Fluoro rubber (DuPont "Viton GLT600S") 100 parts by weight Calcium carbonate (surface treatment with fatty acid)
(Shiraishi Calcium Co., Ltd. “Shiraka Hana CC” (average particle size: 50 nm)) 13 parts by weight MT carbon (Cancarb Co., Ltd. “N990”) 0.5 parts by weight
Zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.) 4 parts by weight Bengala (“Brown # 601” manufactured by Remitz Color) 3 parts by weight Fatty acid salt (“NS Soap” manufactured by Kao) 1 part by weight 2,5-dimethyl-2,5 -Di (tert-butylperoxy) hexyne-3
(“Perhex 25B40” manufactured by NOF Corporation) 1.5 parts by weight Triallyl isocyanurate (“TAIK WH-60” manufactured by Nippon Kasei Co., Ltd.) 4 parts by weight

  The amount of calcium carbonate was adjusted so that the rubber hardness would be 70 degrees (according to the following measurement method), and each compounding component (excluding the vulcanized component) was put into a 3 L kneader and kneaded for 20 minutes. After completion of the kneading, the mixture was discharged from the kneader, and a fluororubber composition was prepared by blending a crosslinking agent and a crosslinking accelerator with a 10-inch roll.

  The resulting fluororubber composition was press vulcanized at 180 ° C. for 6 minutes, and further subjected to secondary vulcanization at 230 ° C. for 15 hours to obtain a 2 mm sheet (crosslinked fluororubber). The following evaluation was performed using the obtained 2 mm sheet. The results are shown in Table 1.

<Evaluation method>
(Color tone)
Visually observed color

(Normal physical properties)
1) Rubber hardness Hs; measured with a type A durometer according to JIS K 6253.
2) Tensile strength TB (MPa); compliant with JIS K 6251.
3) Elongation EB (%): compliant with JIS K 6251 (measured at 23 ± 3 ° C.).

(Low temperature)
1) TR-10 value In accordance with JIS K 6261, with a low-temperature elastic recovery tester, the sample was stretched 50%, the temperature was lowered, and the glass was vitrified below the glass transition point (Tg), and then the temperature was gradually raised. Then, the distortion of the sample was relaxed, and a temperature at which 10% of the initial elongation was recovered was measured as a TR-10 value.
2) 50% impact embrittlement temperature According to JIS K 6261, when impact bending is applied to the test piece, 50% of the total number of the test piece is broken (visible cracks, cracks, torn holes, two or more The temperature at which at least one phenomenon of complete separation into fragments appears) was measured as the 50% impact embrittlement temperature.

(Heat aging test)
Based on JIS K6257, the normal-state physical-property change (rate) after heating at 230 degreeC x 70 hours was evaluated. Specifically, the rubber hardness Hs was determined as a change from the normal physical properties. Moreover, about the tensile strength TB and elongation EB, the change rate with the said normal state physical property was calculated | required.

Comparative Example 1
In Example 1, the calcium carbonate in the compounding components was evaluated in the same manner in place of 35 parts by weight of barium sulfate (“B-54” manufactured by Sakai Chemical Industry Co., Ltd .; average particle diameter 900 nm). The results are shown in Table 1.

  In addition, through Comparative Examples 1-4, the compounding quantity of the filler replaced with calcium carbonate is adjusted so that the rubber hardness of the obtained fluororubber crosslinked body may be 70 degree | times.

Comparative Example 2
In Example 1, the calcium carbonate in the compounding components was evaluated in the same manner in place of 45 parts by weight of barium sulfate (“BA” manufactured by Sakai Chemical Industry Co., Ltd .; average particle diameter: 4000 nm). The results are shown in Table 1.

Comparative Example 3
In Example 1, the calcium carbonate in the compounding components was similarly evaluated in place of 10 parts by weight of diatomaceous earth (“Silica 6B” manufactured by Chuo Silica Co., Ltd .; average particle diameter 6400 nm). The results are shown in Table 1.

Comparative Example 4
In Example 1, the calcium carbonate in the compounding components was similarly evaluated in place of 27 parts by weight of calcined talc (“Enstack 24” manufactured by Asada Flour Mills; average particle size of 6000 to 9000 nm). The results are shown in Table 1.

Reference Example In Example 1, the calcium carbonate and the red pepper in the blending components were not added, and the amount of MT carbon (“N990” manufactured by Cancarb) was changed to 28 parts by weight and evaluated in the same manner. The results are shown in Table 1.

  In all of the comparative examples, the tensile strength was deteriorated as compared with the carbon blend (reference example). In particular, in Comparative Examples 2 and 4, the deterioration of the 50% impact embrittlement temperature was also significant. On the other hand, in Example 1 containing calcium carbonate, the colorable fluororubber composition and crosslinkable fluororubber having physical properties that are equally superior in impact embrittlement temperature and tensile strength compared to the carbon formulation (reference example). You can see that the body has been obtained.

Claims (7)

  Fluorine rubber made of a fluoropolymer capable of peroxide vulcanization, a peroxide-based cross-linking agent, and calcium carbonate, and containing 5 to 30 parts by weight of the calcium carbonate per 100 parts by weight of the fluoropolymer A fluororubber composition characterized in that it is possible.   The peroxide vulcanizable fluoropolymer is a vinylidene fluoride-perfluoro (methyl vinyl ether) -tetrafluoroethylene ternary fluoropolymer having a TR-10 value of -40 ° C to -25 ° C. The fluororubber composition according to claim 1, wherein   3. The fluororubber composition according to claim 1, wherein 10 to 20 parts by weight of calcium carbonate is blended per 100 parts by weight of the fluoropolymer.   4. The fluororubber composition according to claim 1, wherein the blending amount of carbon black is 0.5 parts by weight or less per 100 parts by weight of the fluoropolymer.   A method for producing a crosslinked fluororubber, wherein the fluororubber composition according to any one of claims 1 to 4 is heat-treated after kneading.   The method for producing a cross-linked fluororubber according to claim 5, wherein the cross-linked fluororubber has an impact embrittlement temperature of -30 ° C or lower and a tensile strength of 15 MPa or higher.   A cross-linked fluororubber obtained by the method for producing a cross-linked fluororubber according to claim 5 or 6 is used for a gasket for an intake manifold.