WO2003074625A1

WO2003074625A1 - Sealing material

Info

Publication number: WO2003074625A1
Application number: PCT/JP2003/002533
Authority: WO
Inventors: Katsusada Tokuhira; Yutaka Ueta; Hiroshi Aihara
Original assignee: Daikin Industries, Ltd.
Priority date: 2002-03-05
Filing date: 2003-03-05
Publication date: 2003-09-12
Also published as: JPWO2003074625A1

Abstract

A sealing material which has excellent crack resistance under high-temperature high-compression conditions and can be made to have reduced compression set according to need. The sealing material comprises a fluoroelastomer composition containing a fluoroelastomer, and is characterized in that the fluoroelastomer is a copolymer obtained from monomer ingredients comprising vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene and has a weight-average molecular weight of 400,000 to 700,000.

Description

Specification

Sealing materials Technical field

The present invention relates to a sealing material comprising a high molecular weight fluorine-containing elastomer composition, and more particularly, to a sealing material which is excellent in crack resistance under high temperature and high compression, and which can further improve compression permanent distortion resistance if desired. About materials. Background art

An oxygen sensor (o ₂ sensor) for detecting oxygen concentration is used, for example, for detecting oxygen concentration in exhaust gas from an internal combustion engine of an automobile. Although the automotive oxygen sensor is usually protected by a metal tube, it is attached to a hot exhaust pipe, etc., and is exposed to a hot exhaust gas stream containing a large amount of oxidizing substances. It is necessary to have excellent chemical properties.

Oxygen sensors for automobiles are often installed below the vehicle floor, such as those that are installed downstream of a catalyst that purifies exhaust gas and those that require catalyst deterioration detection. In this case, the oxygen sensor for automobiles must be equipped with mechanical shock resistance, heat shock resistance, waterproofness, etc., because it receives vibration and impact from the engine and the road surface, stone splashes, and external shocks such as being wet. Is also required.

Oxygen sensors for automobiles are usually cylindrical, and the air used as a reference for the oxygen concentration is introduced into the oxygen concentration detecting element, and the electrical output of the oxygen concentration detecting element at the back of the cylinder is taken out. Built-in lead wire. The lead wire is disposed so as to penetrate a sealing material called a bush so as to be fixed without coming into contact with each other at a portion taken out from the oxygen sensor for a vehicle.

This seal material usually has a cylindrical shape as a basic shape.In use, a lead wire is passed through a through hole extending in the height direction of several previously provided cylinders, and then pressure is applied in the radial direction. Perform additional caulking. In the present specification, the radial direction means a direction perpendicular to the center line in the height direction of the cylinder from the side surface of the cylinder.

This sheathing material is compressed to some extent by caulking, and the lead wire is securely fixed. It is desirable to have elasticity so as to exhibit sealing properties such as waterproofness and airtightness.In addition, from the installation location, properties such as heat resistance and impact resistance are similar to those of the automotive oxygen sensor itself. It is also desirable to have. Therefore, as a sealing material, a fluororubber having these characteristics has been often used.

As for the sealing material, it is desirable that the compression set is small so as to exhibit excellent sealing characteristics, since the residual stress strain due to caulking causes cracks. However, in conventional fluororubbers, although the compression set could be reduced by increasing the crosslink density by using a vulcanizing agent, there was a problem that the cracking property due to high compression deteriorated.

In recent years, as engine and equipment have become more sophisticated and environmental protection has become more conscious, there has been a demand for more precise sensor control. Is moving upstream of the exhaust gas flow. The exhaust gas stream is hotter upstream.

In recent years, with the increase in the density of automobile engine rooms, the size of engines has been desired to be reduced in order to expand the living space inside the vehicles. The demand for development is high because downsizing of engines contributes to lighter weight and lower fuel consumption of automobiles. Some oxygen sensors are installed in such high temperature areas.

In the past, cracking resistance under high compression and compression set resistance tended to deteriorate as the temperature increased.However, as a fluororubber used as a sealing material, as described above, the operating environment was higher than before. In such a case, it has been required that these characteristics are not impaired.

Conventionally, as a fluororubber for a sealing material, a binary polymer such as vinylidene fluoride Z tetrafluoroethylene copolymer, or a bi-lidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer has been used. Terpolymers such as [VdF / TFE / HFP copolymer] have been mainly used. Summary of the Invention

An object of the present invention is to provide a sealing material which is excellent in crack resistance under high temperature and high compression conditions, and can further improve compression set resistance if desired. It is in.

The present invention relates to a sealing material comprising a fluorine-containing elastomer composition, wherein the fluorine-containing elastomer composition comprises a fluorine-containing elastomer, and the fluorine-containing elastomer is vinylidene fluoride A copolymer obtained from a monomer component containing tetrafluoroethylene and hexafluoropropylene, wherein the fluorinated elastomer has a weight average molecular weight of 400,000 to 700,000. It is a sealing material characterized by these.

The present invention relates to a sealing material comprising a fluorine-containing elastomer composition, wherein the fluorine-containing elastomer composition comprises a fluorine-containing elastomer, and the fluorine-containing elastomer is vinylidene fluoride Is a copolymer obtained from a monomer component containing tetrafluoroethylene and hexafluoropropylene, and the above-mentioned fluorinated elastomer is a raw rubber obtained by measuring according to JISK 6251 (1993). A sealing material having a tensile strength of 3 to 15 MPa. Detailed Disclosure of the Invention

Hereinafter, the present invention will be described in detail.

The first sealing material of the present invention is a scenery material made of a fluorine-containing elastomer composition, wherein the fluorine-containing elastomer composition is made of a fluorine-containing elastomer, and the fluorine-containing elastomer is It has a weight average molecular weight of 400,000 to 700,000. If it is less than 400,000, crack resistance may deteriorate, and if it exceeds 700,000, the Mooney viscosity may increase and the moldability may decrease. A preferred lower limit is 450,000, a more preferred lower limit is 550,000, a preferred upper limit is 650,000, and a more preferred upper limit is 600,000. The crack resistance is a property in which the sealing material does not crack.

In the present specification, the weight average molecular weight is dissolved to be 0.1 wt% of the above fluorine-containing elastomer flush with the Tet Rahi Dorofuran, two of TSKg el GMH _XL as GPC columns, G 3000 H _XL 1 column and 1 G 2000 H _XL (trade name, both manufactured by Tosoh Corporation), TSKg uardc 0 as guard column Use 1 umn H _XL- H (trade name, manufactured by Tosoh Corporation), set the column temperature to 40 ° C, and use a gel permeation chromatograph (trade name: HLC-8020, manufactured by Tosoh Corporation). Using a RI detector (manufactured by Tosoh Corporation) with the detector temperature set to 35 ° C, using a monodisperse polystyrene (manufactured by Tosoh Corporation) as a standard polymer for the molecular weight calibration curve. .

The second sealing material of the present invention is a sealing material made of a fluorinated elastomer composition, wherein the fluorinated elastomer composition is made of a fluorinated elastomer, and the fluorinated elastomer is JISK It is characterized in that the raw rubber has a tensile strength of 3 to 15 MPa measured according to 6251 (1993). If it is less than 3 MPa, crack resistance may deteriorate, and if it exceeds 15 MPa, moldability may decrease. A preferred lower limit is 3.5 MPa, and a preferred upper limit is 14 MPa.

The second sealing material of the present invention is to improve the crack resistance, from the viewpoint of capable of maintaining the moldability, it preferably has a weight-average molecular weight of the fluorine-containing elastomer one are ^400000-7 00000. A more preferred lower limit is 450,000, a still more preferred lower limit is 550,000, a more preferred upper limit is 650,000, and a still more preferred upper limit is 600,000.

In the first sealing material of the present invention and the second sealing material of the present invention, the fluorinated elastomer is vinylidene fluoride [VdF], tetrafluoroethylene [TFE], and hexafluoropropylene. It is a ternary copolymer obtained from a monomer component containing [HFP]. When the ternary copolymer is used, the obtained sealing material has elasticity, excellent sealing properties, and excellent chemical resistance and heat resistance. The terpolymer may be obtained by polymerizing perfluoro (alkyl vinyl ether) in addition to VdF, TFE and HFP.

The first sealing material of the present invention is characterized in that the fluorine-containing elastomer is adjusted by adjusting the amount of Vd F, the amount of perfluorocarbon (alkyl vinyl ether) and / or the amount of perfluoro (alkyl vinyl ether). A material having a weight average molecular weight in the above range can be obtained, and a material having a tensile strength in the above range can be obtained in the second sealing material of the present invention.

The following description of the sealing material of the present invention will be applied to the above-described present invention unless otherwise specified. This is common to the first seal member described above and the second seal member of the present invention.

The sealing material of the present invention has a compression ratio of 46% according to ASTM D 1414 (1994) 280. When kept at C for 24 hours, it can be obtained as if it did not crack. Although the compression ratio is usually set to 25% in the above-described measurement by ASTM, the sealing material of the present invention does not crack even under more severe conditions. When conforming to the above ASTM D 1414 (1994), the sealing material is used as it is without cutting, etc., as a test object, and is applied in the height direction using a predetermined compression device so that the compression ratio is 46%. And leave it under the above heating conditions.

In the present specification, the phrase "does not cause cracks" means that the test object is returned to room temperature under the above-mentioned heating conditions, and that the seal material is visually cracked in a state where it is removed from the compression device. Means that is not confirmed. When the presence or absence of cracks is visually inspected, deformation such as crushing or bending may be applied to the test object by applying a pressure to a specific direction using a finger, a hand, an instrument, or the like.

By adjusting the amount of a compounding agent such as a vulcanizing agent described below, the sealing material of the present invention can be further heated to 280 ° C. under the condition of a compressibility of 66% in accordance with ASTM D 1414 (1994). When kept for 24 hours, it can be obtained without cracking.

When the sealing material of the present invention is configured as described above, it can be generally considered that cracks hardly occur under the environment where the sealing material is used. .

The sealing material of the present invention also has a compression set of 45 to 55% when kept at 280 ° C for 100 hours under a condition of a compression rate of 25% in accordance with JISK 6262 (1997). be able to.

When the compression set is within the above range, the sealing material of the present invention secures waterproofness and airtightness by a compression process such as caulking, and is frequently used at high temperatures. It can be suitably used for metal materials and the like.

The above-mentioned fluorinated elastomer composition usually comprises a vulcanizing agent and a vulcanization accelerator in addition to the above-mentioned fluorinated elastomer. The vulcanizing agent and the vulcanization accelerator are used for vulcanizing the fluorinated elastomer.

In the vulcanization, the same or different polymer chains of the fluorinated elastomer are cross-linked by the vulcanizing agent, and the cross-linking forms a vulcanized fluororubber.

The above-mentioned fluorinated elastomer can be used as the sealing material of the present invention having improved tensile strength and good elasticity by the above-mentioned vulcanization.

The vulcanizing agent and vulcanization accelerator used in the vulcanization step vary depending on the use of the obtained sealing material and the vulcanization system. The above vulcanization systems are generally broadly classified into polyol vulcanization systems, peroxide vulcanization systems, and polyamine vulcanization systems.Polyol vulcanization systems include polyol vulcanization agents, and peroxide vulcanization systems include peroxide vulcanization systems. Vulcanizing agent, polyamine A polyamine vulcanizing agent is used for the vulcanizing system.

The vulcanized fluororubber vulcanized by the polyol vulcanization system has a carbon-oxygen bond at the cross-linking point, has a small compression set, has good moldability, and has excellent sealing properties. Since it has the feature of being excellent, it is suitable for the sealing material of the present invention.

Since the vulcanized fluororubber vulcanized by the peroxide vulcanization system has a carbon-carbon bond at a cross-linking point, the vulcanized fluororubber and the carbon vulcanization system having a carbon-oxygen bond at a cross-linking point -Compared to the polyamine vulcanization system having a nitrogen double bond, it is characterized by having better chemical resistance and steam resistance.

The vulcanized fluoro rubber vulcanized by the polyamine vulcanization system has a carbon-nitrogen double bond at a cross-linking point, and is characterized by excellent dynamic mechanical properties. The vulcanized fluororubber vulcanized by the polyamine vulcanization system is compared with the vulcanized fluororubber vulcanized using the polyol vulcanization system or the peroxide vulcanization system. The above-mentioned compression set, which is the most important physical property as a sealing material, may be large. Therefore, it is preferable to use the above-mentioned polyol vulcanization system or the above-mentioned peroxide vulcanization system for the above-mentioned fluorinated elastomer composition, and to use the above-mentioned polyol vulcanization system from the viewpoint of excellent sealing properties as described above. Is more preferred. As the polyol vulcanizing agent used in the polyol vulcanizing system, a compound conventionally known as a fluorine rubber vulcanizing agent can be used.For example, a polyhydroxy compound, particularly, because of its excellent heat resistance Polyhydroxy aromatic compounds are preferably used.

The polyhydroxy aromatic compound is not particularly limited, and examples thereof include 2,2-bis (4-hydroxyphenyl) propane (hereinafter, referred to as “bisphenol A”), 2,2-bis (4-hydroxyphenyl) Fluoropropane (hereinafter referred to as "bisphenol AF"), resorcinol, 1,3-trihydroxybenzene, 1,7-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydrido b carboxymethyl naphthalene, 4, 4 'Jihi Dorokishijifue two Honoré, 4, 4 ⁷ - dihydric mud carboxymethyl steel Honoré Ben, 2, 6 dihydric mud carboxymethyl anthracene, human Dorokinon, catheter call, 2, 2-bis (4-arsenate Dorokishifueniru) Butane (hereinafter referred to as "bisphenol 8"), 4,4-bis (4-hydroxyphenyl) valeric acid, 2,2-bis (4-hydroxy) Shifueniru) tetra unloading Reo Logistics black port propane, 4, 4, one dihydric mud carboxymethyl di Hue Nino less ^^ Hong, 4, A 'Jihi mud carboxymethyl Ziv Eni Honoré ketone, tri (4-arsenate Dorokishifueniru) methane, 3, 3 ^7, 5,5 ^; -tetrachlorobisphenol A, 3,3 ', 5,5'-tetrabromobisphenol A and the like. These polyhydroxy aromatic compounds may be an alkali metal salt, an alkaline earth metal salt, or the like. However, when the copolymer is pulverized using an acid, it is preferable not to use the above metal salt.

In the polyol vulcanization system, a vulcanization accelerator is usually used in combination with the polyol vulcanization agent. When the vulcanization accelerator is used, the vulcanization reaction can be promoted by promoting the formation of an intramolecular double bond by dehydrofluorination of the main chain of the fluorine-containing elastomer.

As the vulcanization accelerator, a compound having a property that it is difficult to be added to the main chain of the fluorinated elastomer is preferable, and an onium compound is generally used. The above-mentioned cation compound is not particularly limited, and examples thereof include ammonium compounds such as quaternary ammonium salts; phosphonium compounds such as quaternary phosphonium salts; oxonium compounds; and sulfonium compounds. Quaternary ammonium salt, quaternary phos Honium salts are preferred.

The above quaternary ammonium salt is not particularly limited, and examples thereof include 8-methyl-1,8-diazabicyclo [5.4.0] —7-indesenium chloride, and 8-methyl-1 , 8—Diaza-bik mouth [5.4.0] — 7—Dendecenium iodide, 8—Methyl-1,8-diazabicyclo [5.4.0] —7—Dendecenium hydroxide , 8_Methyl-1,8-diazabicyclo [5.4.0] — 7-indesenemumethylsnorefreate, 8-ethyl-1,8-diazabicyclo [5.4.0]-7 —Dedecenium bromide, 8-Propyl—1,8—Diazabicyclo [5.4.0] 1—7-Indecenium bromide, 8—Dodecyl-1,8—Diazabicyclo [5.4.0] 1-7-ndenesenium chloride, 8-1 dodecyl 1,8-diaza-bix mouth [5.4.0] 1-7-ndenesenium chloride, 8-d Kosyl 1, 8-diaza-bicyclo [5.4.0] — 7 — ndesenium chloride, 8-tetracosyl 1 '8 — diaza-bisic mouth [5. 4.0] — 7-din Decenium chloride, 8-Penzinole 1,8—Zi-Abi-cyclo [5.4.0] — 7-Desenidium chloride [D BU-B], 8-Benzinole 1, 8—Jazin mouth [5.4.0] — 7—Dendecenium hydroxyide, 8—phenethyl-1,8—Jazin mouth [5.4.0] 1—7-pin Decenium chloride, 8-(3-feuerp mouth pill)-1,8-diaza-bishik mouth [5.4.0] 17-undecenium chloride.

The quaternary phosphonium salt is not particularly restricted but includes, for example, tetrabutylphosphonium chloride, benzyltriphenylinolephosphonium chloride [BTPPC], benzyltrimethinolephosphonium chloride, benzinoletributylphosphite. Num chloride and the like.

Examples of the vulcanization accelerator include a solid solution of the quaternary ammonium salt or quaternary phosphonium salt and bisphenol AF, and a chlorine-free solution disclosed in JP-A No. 11-147891. A single vulcanization accelerator or the like can also be used.

The vulcanizing agent is preferably added in an amount of 0.95 to 1.15 parts by mass on a solid basis with respect to 100 parts by mass of the fluorinated elastomer. If the amount is less than 0.95 parts by mass, the crosslinking density may decrease and the compression set may increase. Otherwise, the crosslink density may be too high and the crack resistance may decrease. A more preferred lower limit is 0.98 parts by mass, and a more preferred upper limit is 1.1 parts by mass. The vulcanization accelerator is preferably compounded in an amount of 0.1 to 0.3 parts by mass on a solid content basis with respect to 100 parts by mass of the fluorinated elastomer. If the amount is less than 0.15 parts by mass, the time required for vulcanization may be prolonged. If the amount exceeds 0.3 parts by mass, the bridge may proceed too much and the crack resistance may decrease. A more preferred lower limit is 0.18 parts by mass, and a more preferred upper limit is 0.25 parts by mass.

The sealing material of the present invention achieves both crack resistance and compression set resistance by setting the blending amount of the vulcanizing agent and the vulcanization accelerator in the fluorine-containing elastomer and composition in the above range. can do.

The fluorinated elastomer composition is preferably a composition obtained by mixing an acid acceptor and / or a filler in addition to the fluorinated elastomer, the vulcanizing agent and the vulcanization accelerator optionally used.

The acid acceptor is used in the polyamine vulcanization system and the polyol vulcanization system to neutralize acidic substances generated during the vulcanization. The acid acceptor is not particularly limited, and examples thereof include magnesium oxide, lead oxide, and calcium oxide. As the above-mentioned acid acceptor, magnesium oxide is preferable from the viewpoint of giving excellent thermal stability to the above-mentioned sealing material.

The acid acceptor is preferably blended in an amount of 3 to 25 parts by mass with respect to 100 parts by mass of the fluorinated elastomer. If the amount is less than 3 parts by mass, crack resistance may deteriorate, and if it exceeds 25 parts by mass, scorch may occur. A more preferred upper limit is 12 parts by mass. The scorch is a phenomenon in which the fluorine-containing elastomer composition starts vulcanization during storage or during processing before primary vulcanization described below.

It is preferable that the above-mentioned fluorine-containing elastomer yarn is obtained by blending calcium hydroxide as a vulcanization accelerator in the above-mentioned polyol vulcanization system.

The calcium hydroxide can accelerate the vulcanization reaction by reacting with the vulcanization accelerator to remove hydrofluoric acid and reactivate the vulcanization accelerator.

The calcium hydroxide is used in the polyol vulcanization system, It is preferable to add 0.5 to 12 parts by mass based on the solid content to 100 parts by mass of the stoma. If the amount is less than 0.5 part by mass, the vulcanization rate may not be accelerated. If the amount is more than 12 parts by mass, the elasticity of the obtained sealing material of the present invention deteriorates, and the compression set increases. There are cases. A preferred lower limit is 1 part by mass, a more preferred lower limit is 2 parts by mass, and a preferred upper limit is 8 parts by mass.

The above-mentioned filler is generally used for the purpose of lowering the molding shrinkage of the above-mentioned sealing material and the like, and the mechanical properties such as elongation, tensile strength, compression set and crack resistance of the above-mentioned sealing material are reduced as much as possible. Those that do not are used.

The filler is not particularly limited, and examples thereof include thermal black, furnace black, channel black, mineral black (bituminous filler), talc, calcium silicate, white carbon, calcium carbonate, barium sulfate, and clay. .

The filler preferably contains 10 to 50 parts by mass based on 100 parts by mass of the fluorinated elastomer. If the amount is less than 10 parts by mass, the molding shrinkage may not be sufficiently reduced by blending. If the amount is more than 50 parts by mass, the hardness may be increased and the moldability may be deteriorated. A more preferred upper limit is 30 parts by mass.

The sealing material of the present invention can be produced by molding the above-mentioned fluorinated elastomer composition using a generally used rubber processing apparatus. The sealing material of the present invention is produced by, for example, kneading, molding, primary vulcanization, and secondary vulcanization of the fluorine-containing elastomer composition in this order.

The kneading is performed by kneading the fluorine-containing elastomer, the vulcanizing agent and the vulcanization accelerator optionally used, the vulcanization accelerating aid, the acid acceptor and / or the filler, This is a process of uniformly mixing using an intermix, Banbury mixer, or the like.

The kneading method differs depending on the vulcanization system. In the polyol vulcanization system, for example, the following method using a kneading roll machine can be used. That is, the roll temperature is forcibly cooled with cooling water of 25 to 30 ° C, and the gap between the dies is adjusted to about 2 mm. The above-mentioned fluorine-containing elastomer is charged as a raw material into the kneading roll machine and wound around a roll to form a band of the above-mentioned fluorine-containing elastomer. Vulcanizing the above band Add a vulcanizing agent and a vulcanization accelerator, knead the mixture repeatedly, set the roll interval to lmm or less, perform several passes, and then adjust the roll interval to about 2mm, insert carbon and other fillers, and then oxidize. An acid acceptor such as magnesium and a vulcanization accelerating aid such as calcium hydroxide are added, and the roll is rotated 5 to 10 times to perform kneading. Finally, the mixture is kneaded for 20 to 30 minutes, the roll interval is set to 2Η1Π1 or less, and several times of tight milling is performed.

However, before kneading the fluorinated elastomer composition, mastication may be performed on the fluorinated elastomer contained in the fluorinated elastomer composition for the purpose of enhancing plasticity. .

The kneaded product formed into a predetermined shape by molding is subjected to primary vulcanization by heating at 150 to 230 ° C for about 1 to 30 minutes using a compression press, an injection molding machine, or the like. . The molding method using a compression press is a molding method suitable for fluororubber having a larger weight average molecular weight than other molding methods, and is suitably used as a step of molding the sealing material of the present invention.

The sealing material formed by the primary vulcanization is preferably subjected to secondary vulcanization using an air oven. The secondary vulcanization is carried out for the purpose of completing the reaction of the primary vulcanization, decomposing the remaining vulcanizing agent without undergoing a cross-linking reaction, and dissipating gas generated during vulcanization. By performing the secondary vulcanization, the mechanical properties such as the tensile strength and the permanent compression set of the sealing material of the present invention can be improved as compared with the case where only the primary vulcanization is performed.

The conditions of the above secondary vulcanization vary depending on the vulcanization system, such as polyamine vulcanization system at 180 to 220 ° C for about 16 to 24 hours, and polyol vulcanization system for 210 to 26 hours. In general, it is carried out at 0 to about 16 to 24 hours, and for the peroxide vulcanization system, at 160 to 200 ° C for about 2 to 24 hours.

The sealing material of the present invention has crack resistance and pressure-resistant compression set under high-temperature and high-compression conditions as described above. Therefore, it is possible to apply pressure such as caulking to ensure the sealing property. Therefore, it can be suitably used for an application that needs to maintain the sealing property when used for a long time at a high temperature.

The use of the sealing material of the present invention is not particularly limited. Engine main body, main motion system, valve system, lubrication / cooling system, fuel system, intake / exhaust system; drive system transmission system; chassis steering system; brake system; basic electrical components of electrical components, control system electrical components Heat resistance of parts and electrical components, etc. * Oil resistance · Fuel oil resistance · Antifreeze liquid resistance for engine cooling · Gaskets requiring steam resistance ゃ Non-contact and contact type packings (self-sealing packing, piston Seals such as rings, split-ring type packings, mechanical seals, and oil seals. The sealing material used for the engine body of the automobile engine is not particularly limited. For example, gaskets such as cylinder-to-head gasket, cylinder-to-head cover gasket, oil pan packing, general gasket, O-ring, packing, and timing Seals, such as a belt cover gasket, are mentioned.

The seal material used for the main motion system of the automobile engine is not particularly limited, and includes, for example, a crankshaft seal, a shaft sealer such as a camshaft sealer, and the like.

The sealing material used for the valve train of an automobile engine is not particularly limited, and examples include a valve stem oil seal of an engine valve.

The sealing material used for the lubrication / cooling system of an automobile engine is not particularly limited, and examples thereof include a seal gasket of an engine oil cooler.

The sealing material used for the fuel system of an automobile engine is not particularly limited, and examples thereof include an oil seal of a fuel pump, a filler seal of a fuel tank, a tank packing, a connector of a fuel tube, an O-ring of a fuel tube, and an injector of a fuel injection device. Examples include a cushion ring, an injector seal ring, an injector o-ring, and a carburetor flange gasket.

The seal material used for the intake and exhaust systems of automobile engines is not particularly limited.For example, intake manifold packings for manifolds, exhaust manifold packings, slotting bodies for slotholes, and body parts for turbochargers. Turbine shaft seals and the like.

The sealing material used for the transmission system of an automobile engine is not particularly limited. For example, an O-ring of an automatic transmission, such as a transmission-related bearing seal, an oil seal, an O-ring, a packing, and the like. And the like.

The sealing material used in the brake system of an automobile engine is not particularly limited, and examples thereof include an oil seal, an O-ring, a packing, a piston cup (rubber cup) of a master cylinder, a caliper seal, and boots. No.

There is no particular limitation on the sealing material used for the electrical components of an automobile engine, and examples thereof include an O-ring and a packing of a car air conditioner.

The seal material of the present invention is more preferably used as a control system electrical component of an automobile engine, particularly as a seal material for a sensor, and is more preferably used as a bush of an oxygen sensor usually used under high temperature and high compression. .

There is no particular limitation on uses other than for automobiles. For example, oil-, chemical-, heat-, steam- or weather-resistant packing, o-rings, and other sealing materials in transportation such as ships and aircraft; Similar packing, o-rings and seals; similar packing, sealing and sealing materials in food plant equipment and food equipment (including household products); similar packing, sealing and sealing in nuclear plant equipment Materials: Similar packings, O-rings, and seal materials for general industrial parts.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

The product names and abbreviations in Tables 1 and 2 and the description are as follows.

FKM: V d FZHF Abbreviation for P-based binary or ternary fluororubber

N-990: Thermal black manufactured by Cancarb

Seast 1 1 6: Furnace black manufactured by Tokai Carbon Co., Ltd.

Mineranole black 325BA: Bituminous filler from Keystone Filament & Mfg

MA-150: Highly active magnesium oxide manufactured by Kyowa Chemical Industry Co., Ltd.

CALD IC 2000: Calcium hydroxide manufactured by Omi Chemical Industry Co., Ltd. Production Example 1 Production of ternary fluorine-containing elastomer

After placing 29 liters of pure water and 29 g of C ₇ F ₁₅ COONH ₄ as an emulsifier in a 48 liter capacity stainless steel autoclave without an ignition source, and thoroughly replacing the system with nitrogen gas, The temperature in the system was raised to 60 ° C. While stirring at 200 rpm, the internal pressure is 15 kgf Z cm, with the mixed gas of \ (1 and << [? And the pound, the molar ratio being VdF: HFP: TFE = 56: 28: 16. ^It was charged to ² G.

Next, a solution of 24 g of ammonium persulfate dissolved in 50 ml of water was injected under pressure using nitrogen to initiate the reaction.

Since the pressure decreases with the progress of the polymerization reaction, the mixed gas of VdF, HFP and TFE is used in a molar ratio of VdF: HFP: TFE = 66.5: 16: 17.5. The internal pressure was maintained at 15 kgf Zc m ² G sequentially, and at the same time, isoi tantan as a chain transfer agent was equally divided into 5 parts based on the reaction yield, and a total amount of 2.5 cm ^{3 was} charged. After 326 minutes from the start, the supply was stopped, the autoclave was cooled, unreacted monomers were released, and a translucent aqueous dispersion having a solid concentration of 20 to 25% by mass was obtained. The obtained aqueous dispersion was subjected to a conventional method, and the precipitated polymer was washed and dried. The tertiary fluorine-containing elastomer having a molar ratio of VdF: TFE: HFP = 65: 20: 15 was used. The best white solid was obtained.

The weight average molecular weight measured by the above method was 55 × 10 ⁴ . Example 1

Based on 100 parts by mass of the tertiary fluorine-containing elastomer obtained in Production Example 1, 10 parts by mass of system 116, 1.0 parts by mass of bisphenol AF, 0.2 parts by mass of BTPPC, and oxidation 3 parts by mass of magnesium and 6 parts by mass of calcium hydroxide were kneaded using a kneading roll machine equipped with two rolls to obtain a kneaded product.

The above kneaded material was press-vulcanized at 180 ° C for 10 minutes, then oven-cured at 260 ° C for 5 hours, then at 300 ° C for 2 hours, and a vulcanized fluoro rubber was produced by polyol vulcanization. (Evaluation)

The following evaluation was performed on the obtained kneaded material or vulcanized fluoro rubber. Table 1 shows the results.

Vulcanizability

A part of the above kneaded material is collected, and the appropriate vulcanization time is measured at 180 ° C using a curast meter (trade name: Kyulast meter Π, manufactured by JSR Corporation) in accordance with JISK 6300. Τ ₉ . Was measured.

Proper vulcanization time τ ₉ . Is the time it took for the torque to reach 90% of its maximum value during vulcanization with a curameter.

The following physical properties of the vulcanized fluoro rubber were measured at room temperature.

1. Tensile strength

The tensile strength was measured using a tensile tester (trade name: Tensilon, manufactured by Orientec) in accordance with JIS K6251 (1993).

2. Elongation

The elongation was measured using a tensile tester (trade name: Tensilon, manufactured by Orientec Co., Ltd.) according to JIS 6251 (1993).

3. Hardness

The hardness was measured using a type II durometer (trade name: ASKER, manufactured by Kobunshi Keiki Co., Ltd.) according to JIS K 6253 (1997).

4. Specific gravity

The specific gravity was measured by an automatic hydrometer (trade name: DENS I METER, manufactured by Toyo Seiki Co., Ltd.) by a specific gravity measurement method in accordance with the JIS K 6268 II method. Compression set

Small test specimens (inner diameter 13 mm, thickness 6.3 mm) were prepared from the above vulcanized fluoro rubber. For each of the above small test specimens, a compression ratio of 25% and a After holding for 0 hour, 146 hours and 168 hours, the compression set was measured according to JISK 6262 (1997). Crack resistance

The above vulcanized fluoro rubber was processed into an O-ring according to a conventional method. The above-mentioned ring was P-24 (inner diameter 23.7mm, thickness 3.5mm, O-ring for exercise). Three O-ring samples were prepared and kept at 280 ° C for 24 hours under conditions of a compression ratio of 46% according to ASTM D 1414 (1994), then removed from the compression device and checked for cracks. Each was visually inspected. When the compression ratio is 54% and 66%, check the crack ratio in the same way as when the compression ratio is 46%. Raw rubber tensile strength

The fluorine-containing elastomer was kneaded with a kneading roll, separated, and molded at 120 ° C. for 5 minutes using a hot plate compression molding machine to prepare a sheet having a thickness of 2 mm. A dumbbell-shaped No. 6 test piece was prepared from the above sheet, and a tensile tester (trade name: Tensilon, manufactured by Orientec Co., Ltd.) was used, and the stretching speed was 20 OmrnZ in accordance with JISK 625 1 (1993). The tensile strength was measured in minutes. Example 2

The procedure of Example 1 was repeated, except that the components were blended according to Table 1 with respect to 100 parts by mass of the ternary fluorine-containing elastomer obtained in Production Example 1. In Example 2, it is considered that the crack resistance deteriorated because the concentrations of the vulcanizing agent and the vulcanization accelerator were high. Comparative Example 1

With respect to 100 parts by mass of the solid content of a ternary fluorine-containing elastomer having a weight average molecular weight of 39 × 10 ⁴ and a molar ratio of Vd F: TFE: HF P = 65:20:15, Bisphenol AF 1.5 parts by mass as vulcanizing agent, BTPPC as vulcanization accelerator The procedure of Example 1 was repeated except that 0.6 parts by weight was added. Comparative Example 2

Bisphenol AF 1.7 parts by mass based on 100 parts by mass of the solid content of the VdF / HFP copolymer having a weight average molecular weight of less than 20 × 10 ⁴ and a molar ratio of VdF: HFP = 78: 22 , And, and the procedure of Example 1 was repeated except that 0.3 parts by mass of BTPPC was used. Comparative Example 3

Bisphenol AF 1.5 mass based on 100 mass parts of solid content of VdFZHFP copolymer having a weight average molecular weight of less than 20 × 10 ⁴ and a molar ratio of VdF: HFP = 78: 22 And the procedure of Example 1 was repeated except that 0.18 parts by mass of DBU-B was used. Comparative Example 4

Bisphenol AF1 has a weight average molecular weight of less than 20 × 10 ⁴ and a molar ratio of VdF: HFP = 78: 22. The procedure of Example 1 was repeated except that 4 parts by mass and 0.21 part by mass of DBU-B were used. Comparative Example 5

The weight average molecular weight is less than 20 × 10 ⁴ and the molar ratio is VdF: HFP = 78: 22. The solid content of 100 parts by mass of the VdFZHFP copolymer is 100 parts by mass of bisphenol AF1.5. The procedure of Example 1 was repeated except that 0.26 parts by mass of DBU-B and 0.26 parts by mass of DBU-B were used.

From Table 1, the crack resistance is preferably a ternary copolymer than a binary copolymer, among others, _c crack having a weight average molecular weight was found to be a first embodiment which is 550,000 is good As for the properties, it was found that Example 1 where the tensile strength of raw rubber was as high as 1 OMPa and the tensile strength of vulcanized fluorine rubber was as high as 23.5 MPa was excellent. From Table 1, it was found that when the weight average molecular weight was high, the tensile strength of the raw rubber tended to be high. Example 3

For 100 parts by weight of the tertiary fluorine-containing elastomer obtained in Production Example 1, 1 part by weight of bisphenol AF, 8 parts? The procedure of Example 1 was repeated except that 0.2 parts by mass of 部 was used.

However, regarding vulcanizability, the appropriate vulcanization time T ₉ . Was measured according to JISK 6300, and the compression set was measured at 280 ° C. for 100 hours and according to JISK 6262 (1997). Examples 4 to 13

The procedure of Example 3 was repeated except that each component was blended according to Table 2 with respect to 100 parts by mass of the ternary fluorine-containing elastomer obtained in Production Example 1.

Table 2

According to Table 2, the amount of the vulcanizing agent was 0.1% with respect to 100 parts by mass of the fluorine-containing elastomer.

Examples 3 to 7 and Examples 10 to 11, which are in the range of 95 to 1.15 parts by mass, and in which the compounding amount of the vulcanization accelerator is in the range of 0.15 to 0.3 parts by mass, It was found that both crack resistance and compression set resistance were improved. The amount of vulcanizing agent is 0.95 ~

It was found that Example 12 within the range of 1.15 parts by mass had improved compression set resistance as compared with Example 13. Comparative Example 6

Crack resistance evaluation performed in Example 1 was performed on perfluoroelastomer (trade name: Karlez 4079, manufactured by DuPont). However, crack resistance was measured at 280 ° C for 24 hours under conditions of a compressibility of 66% in accordance with ASTM D 1414 (1994), then removed from the compression device, and the presence or absence of cracks was visually inspected. As a result, it was found that all of the three prepared samples were fragile and fractured.

It was found that Examples 1 to 13 were superior to Comparative Example 6 in crack resistance under high temperature and high compression. Industrial applicability

Since the sealing material of the present invention has the above-described structure, it has excellent crack resistance even under high temperature and high compression, and can also have good compression set resistance if desired.

Claims

The scope of the claims

1. A sealing material comprising a fluorine-containing elastomer composition,

The fluorinated elastomer composition is composed of a fluorinated elastomer, and the fluorinated elastomer is a monomer component containing vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. A seal material characterized in that the fluorine-containing elastomer has a weight average molecular weight of 400,000 to 700,000.

2. A sealing material comprising a fluorine-containing elastomer composition,

The fluorinated elastomer composition is composed of a fluorinated elastomer, and the fluorinated elastomer is formed from a monomer component containing vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. The resulting copolymer, wherein the fluorinated elastomer has a tensile strength of raw rubber of 3 to 15 MPa measured according to JISK 6251 (1993)

A sealing material characterized by that:

3. The sealing material according to claim 2, wherein the fluorine-containing elastomer has a weight average molecular weight of 400,000 to 700,000.

4. Claims 1, 2, or 3 that do not crack when exposed to 280 ° C for 24 hours under conditions of a compressibility of 46% according to ASTM D 1414 (1994) The sealing material described.

5. The sealing material according to claim 4, wherein the compression ratio is 66%.

6. Compression set is 45-55% when kept at 280 ° C for 100 hours under the condition of 25% compression rate according to JISK 6262 (1997) Claims 1, 2, 3 4. The sealing material according to item 4, 4 or 5.

7. The fluorine-containing elastomer composition further comprises a vulcanizing agent and a vulcanization accelerator,

The vulcanizing agent is 0.95 to 1.15 parts by mass, and the vulcanization accelerator is 0.15 to 0.3 parts by mass, based on 100 parts by mass of the fluorinated elastomer. 7. The seal material according to claim 1, 2, 3, 4, 5, or 6, which is a part by mass.

8. The seal material according to claim 1, wherein the vulcanization system is a polyol vulcanization system, wherein the vulcanization system is a polyol vulcanization system.

9. The sealing material according to any one of claims 1, 2, 3, 4, 5, 6, 7, and 8, which is a sealing material for a sensor.