JP2001131346A - Rubber molding product useful for use in contact with engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a crosslinked molding product of a fluororubber represented by a vinylidene fluoride-hexafluoropropene-based copolymer rubber or a blend body of the fluororubber and a fluororesin, having excellent engine oil resistance. SOLUTION: This rubber molding product comprises a crosslinked material of fluororubber containing an amphoteric oxide and is useful for use in contact with en engine. A polyol crosslinked material, a peroxide-crosslinked material. etc., are used as the crosslinked material of fluororubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber molded product used for engine oil contact. More specifically, the present invention relates to a rubber molded product used for contact with engine oil such as a sealing material for an automobile engine.

[0002]

2. Description of the Related Art Fluoro rubber has excellent heat resistance,
Due to its chemical resistance and compression set resistance, it is used in many applications, including automotive parts. When used as a material for automobile parts, the performance of engine oils has been improved in accordance with the recent improvement in performance and fuel efficiency of automobile engines. For this reason, a large amount of amine-based additives have been blended into engine oils. The parts in contact with the engine oil are required to have excellent amine additive resistance.

[0003] Fluorine rubbers include vinylidene fluoride
Hexafluoropropene copolymer and vinylidene fluoride
Hexafluoropropene-tetrafluoroethylene terpolymer is generally used.Crosslinked molded products of these fluororubbers, such as oil seals, are hardened and deteriorated by engine oil, and cracks occur. It is not suitable for use in a portion where engine oil comes into contact, since it may cause oil leakage. This is probably because the vinylidene fluoride-hexafluoropropene chain site in the polymer main chain reacts with the amine compound and cures. In addition, a remarkable decrease in tensile strength and the like is observed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a crosslinked molded article of fluororubber represented by vinylidene fluoride-hexafluoropropene copolymer rubber, which has excellent engine oil resistance. It is in.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a rubber molded product used for an engine oil contact application comprising a crosslinked product of a fluororubber containing an amphoteric oxide.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The fluororubber is an elastic polymer having a fluorine atom in a molecule and is at least one kind selected from the group consisting of vinylidene fluoride (VdF) and tetrafluoroethylene (TFE). Monomers, selected from the group consisting of hexafluoropropene (HFP), chlorotrifluoroethylene (CTFE), perfluoro (lower alkyl vinyl ether) (FAVE) and propylene (P), which impart elasticity to the fluoropolymer All known fluororubbers, including copolymers with at least one monomer, can be used.

Specifically, VdF-HFP copolymer, VdF-TFE-H
FP terpolymer, VdF-TFE-HFP-PFP (2H-pentafluoropropene) quaternary copolymer, VdF-FAVE copolymer, VdF-TFE-FAVE
Terpolymer, VdF-CTEF copolymer, VdF-TFE-CTFE terpolymer, VdF-FAVE copolymer, VdF-TFE-FAVE terpolymer, T
FE-P copolymer, TFE-VdF-P terpolymer, TFE-FAVE copolymer, and the like.
(Methyl vinyl ether) (FMVE) is used. Further, those obtained by further copolymerizing ethylene, alkyl vinyl ether or the like with these copolymers can also be used. Among these fluororubbers, VdF-HFP copolymer or VdF-T
Vinylidene fluoride-hexafluoropropene copolymer rubber, which is an FE-HFP terpolymer, is preferably used.

The amphoteric oxide compounded in the fluororubber is a compound that generally acts as a base with respect to an acid and as an acid with respect to a base, and specifically includes zinc, cadmium, boron, aluminum, germanium, and the like. These include oxides of tin, lead, arsenic, antimony, bismuth and the like and oxides of medium valence of transition elements.

In general, at the time of cross-linking molding of a fluororubber, an oxide of a divalent metal such as magnesium oxide, zinc oxide, lead oxide, or calcium oxide is blended as an acid acceptor, and hydrogen fluoride or the like generated at the time of crosslinking molding is mixed. It is known that a crosslinked molded article having a good shape can be obtained by supplementing an oxidized compound.

[0010] For example, Japanese Patent Application Laid-Open No. 8-26
No. 9284 discloses that vinylidene fluoride-hexafluoropropene copolymer rubber is capable of amine vulcanization, polyol vulcanization or peroxide vulcanization.
It is stated that an oxide or hydroxide of a valent metal is used, and in the examples, a crosslinking system-as an acid acceptor, an amine crosslinking system-lead oxide, a polyol crosslinking system-magnesium oxide.
Examples of calcium hydroxide, peroxide crosslinked-lead oxide are described. However, the fluororubber composition, which is the object of the present invention, aims at improving the adhesion to metal, and does not mention engine oil resistance or the like at all.

[0011] Similarly, Japanese Patent Application Laid-Open No. 10-1
01741 discloses a fluorine-containing copolymer elastomer obtained by copolymerizing vinylidene fluoride-hexafluoropropene-based copolymer rubber with a small amount of iodotrifluoroethylene, using an iodine atom bonded to a molecular terminal. ZnO, CaO, Ca as acid acceptors for peroxide crosslinking
(OH) ₂ , MgO, it is stated that oxides or hydroxides of divalent metals such as PbO are used, but the fluorine-containing copolymer elastomer which is the object of the present invention is obtained by peroxide crosslinking. It is aimed at improving the compression set resistance, and does not mention engine oil resistance at all.

In the present invention, the fluororubber is crosslinked,
At that time, it has been newly found that by using an amphoteric oxide as the acid acceptor, the engine oil resistance is improved.
This is presumably because the amine-based additive contained in the engine oil is effectively captured by the amphoteric oxide.

The amphoteric oxide used in the present invention includes:
Zinc oxide, aluminum oxide and lead oxide are useful,
Zinc oxide is preferred in view of price, stability, compression set resistance and the like. In order to reduce the number of blending parts, zinc oxide having a small particle size and named as active zinc white is particularly preferable. In addition, together with these amphoteric oxides, an acid acceptor such as a conventionally used oxide or hydroxide of a divalent metal or synthetic hydrotalcite may be used at all.

These amphoteric oxides are used at a ratio of about 3 to 20 parts by weight, preferably 5 to 15 parts by weight, per 100 parts by weight of the fluororubber. If the compounding ratio is lower than this, the purpose of improving the engine oil resistance is not achieved, while if used at a higher mixing ratio, the value of the elongation at normal physical properties decreases, and the improved elongation change rate is offset. Not only does this increase the hardness, but also increases the degree of freedom in the formulation design.

The crosslinking of vinylidene fluoride-hexafluoropropene copolymer rubber, which is preferably used as a fluororubber in the present invention, is carried out using a polyol crosslinking agent. Examples of the polyol-based crosslinking agent include 2,2-bis (4-hydroxyphenyl) propane [bisphenol A] and 2,2-bis
(4-hydroxyphenyl) perfluoropropane [bisphenol AF], hydroquinone, catechol, resorcinol, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone, 2,2-bis Polyhydroxy aromatic compounds such as (4-hydroxyphenyl) butane or alkali metal salts or alkaline earth metal salts thereof are used, and these crosslinking agents are used in an amount of about 0.5 to 10 parts by weight, preferably about 100 parts by weight of the copolymer rubber. Is used in a proportion of about 1 to 5 parts by weight.

Polyhydroxy aromatic compound as a crosslinking agent
When (metal salt) is used, various quaternary ammonium salts or quaternary phosphonium salts are used in an amount of about 0.1 to 10 parts by weight, preferably about 0.1 to 2 parts by weight per 100 parts by weight of the copolymer rubber. It is preferable to use them in combination.

As described above, the polyol crosslinkable vinylidene fluoride-hexafluoropropene copolymer rubber using an amphoteric oxide as an acid acceptor can also be used by blending with a polyol crosslinkable fluororesin. In this case, not only the effect of improving the engine oil resistance but also the effect of improving the normal physical properties of the blend molded article itself is exhibited.

Such a fluororesin has a fluorine atom in its molecule, has a melting point or softening point of not lower than room temperature, preferably not lower than about 120 ° C., more preferably not lower than 140 ° C., and is capable of performing a deHF reaction. A fluororesin having a reaction point, preferably a vinylidene fluoride-hexafluoropropene copolymer, a vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer, or the like is used. For example, in the former case, the copolymerization ratio of hexafluoropropene in the copolymer is desirably about 1 to 10 mol%, preferably about 1 to 5 mol%, from the viewpoint of the crosslinking rate and the like.

The preparation of the blend can be carried out by mixing and kneading a fluororubber and a fluororesin, each of which has been isolated in a solid state, with a mixing roll, kneader, Banbury mixer or the like. The aqueous latex of the fluororubber obtained by the polymerization method and the aqueous latex of the fluororesin are blended with a desired solid content blend ratio (rubber about 95%).
(About 5 to 45% by weight to about 55% by weight of the resin), and a method of coagulating, washing and drying the latex blend at a ratio such that (a) coagulation, washing and 1 drying
In this case, there are advantages such as that the number of times required is short, (b) the kneading time is short, and (c) the dispersibility of the fluororubber in the fluororesin is improved. The coagulation of the aqueous latex was performed using calcium chloride,
In an aqueous salt solution such as sodium chloride and potassium alum,
This is performed by dropping an aqueous latex.

The cross-linking molding of a blend of a fluororubber and a fluororesin is performed by using a polyol-based crosslinker, as in the case of the fluororubber alone.

The vinylidene fluoride-hexafluoropropene copolymer rubber can be peroxide-crosslinked when an iodine group is introduced therein as a crosslinkable group.
As described in JP 11-101741 A, even if an amphoteric oxide is added to such a peroxide crosslinkable vinylidene fluoride-hexafluoropropene copolymer rubber, the engine oil resistance of the crosslinked product is improved. .

In addition to such peroxide-crosslinkable vinylidene fluoride-hexafluoropropene copolymer rubber containing iodine groups, peroxide-crosslinkable fluororubber containing iodine and / or bromine in other molecules However, it is effective to incorporate an amphoteric oxide in order to improve the engine oil resistance of those crosslinked products.

For details of the peroxide-crosslinkable fluororubber containing iodine and / or bromine in the molecule, see Japanese Patent Application Laid-Open No. 5-2392, which describes the invention of the present applicant.
No. 98, which also describes examples of organic peroxides that are cross-linking agents, and that it is preferable to use a polyfunctional unsaturated compound in combination.

Similarly, the peroxide-crosslinkable fluororesin can be made peroxide-crosslinkable by incorporating iodine and / or bromine groups in the molecule, and blended with a peroxide-crosslinkable fluororubber. Can also be used.

The fluororubber containing a crosslinking agent such as a polyol type or a peroxide type and an amphoteric oxide acid acceptor or a blend thereof with a fluororesin further includes carbon black, silica, graphite, clay, talc, diatom, and the like. Fillers or reinforcing agents such as earth, barium sulfate, titanium oxide, wollastonite, etc., lubricants, processing aids, pigments and the like can be appropriately blended and used.

The above components are kneaded using a mixing roll, a kneader, a Banbury mixer and the like to prepare a composition. The prepared composition is subjected to cross-linking molding by heating at about 150 to 220 ° C. for about 0.5 to 10 minutes using a press molding machine, an injection molding machine transfer molding machine or the like. Secondary cross-linking is performed at ~ 250 ° C for about 1-20 hours.

[0027]

The fluororubber blended with an amphoteric oxide as an acid acceptor has not only improved engine oil resistance, but also improved normal physical properties. The use of a blend of the above is more significant.

The rubber molded product of the present invention exhibiting such excellent engine oil resistance is suitably used as various seal materials such as oil seals, O-rings, packings, gaskets, etc., particularly as oil seals for automobile engines.

[0029]

Next, the present invention will be described with reference to examples.

Reference Example 1 In an autoclave having an internal volume of 10 L, 10 g of ammonium perfluorooctanoate and 2 g of sodium hydroxide (for pH adjustment)
After charging 5 L of deionized water and sufficiently replacing the internal space with nitrogen gas, 2.0 g of ethyl malonate was injected. Thereafter, a mixed monomer gas comprising vinylidene fluoride [VdF] 70 mol% and hexafluoropropene [HFP] 30 mol% was injected until the internal pressure became 2.0 MPa · G, and the internal temperature was raised to 70 ° C.

Thereafter, 5 g of ammonium persulfate was added to 150 ml of water.
The polymerization initiator aqueous solution dissolved in was poured into an autoclave to start the polymerization reaction. The internal pressure at this time is 3.2M
Pa · G. When the internal pressure drops to 2.9MPaG, Vd
Using F / HFP (molar ratio 78:22) mixed gas as the dispensing gas, the internal pressure
The operation of press-in until the pressure became 3.0 MPa · G was repeated until the solid content concentration in the produced latex became 30% by weight. As soon as the solid content reached a predetermined level, the reaction was stopped by purging the unreacted gas in the autoclave.

The resulting copolymer was coagulated by adding 5% by weight of alum water to the obtained aqueous latex, washed with water and dried. 2188 g of fluorine-containing copolymer A (conversion rate 85%) is obtained,
The copolymer composition of this copolymer (by ¹⁹ F-NMR) was VdF / HFP = 7
8/22 (mol%), glass transition temperature (by DSC method) -15 ℃
Solution viscosity ηsp / c [1% by weight methyl ethyl ketone (ME
K) The specific viscosity of the solution, 35 ° C.] was 1.00 dl / g. The yield is the amount recovered when the total amount of the obtained aqueous latex is salted out, and the conversion is calculated based on the value. The same applies to the following reference examples.

REFERENCE EXAMPLE 2 10 g of ammonium perfluorooctanoate, 2 g of sodium hydroxide and 5 L of deionized water were charged into an autoclave having a capacity of 10 L, and the internal space was sufficiently replaced with nitrogen gas. Was press-fitted. Then, a mixed gas consisting of vinylidene fluoride [VdF] 27.6 mol% tetrafluoroethylene [TFE] 52.4 mol% hexafluoropropene [HFP] 20.0 mol% was injected until the internal pressure reached 1.0 MPa · G, and the internal temperature was reduced. The temperature was raised to 70 ° C.

Thereafter, 5 g of ammonium persulfate was added to 150 ml of water.
The polymerization initiator aqueous solution dissolved in was poured into an autoclave to start the polymerization reaction. The internal pressure at this time is 1.6M
Pa · G. When the internal pressure drops to 1.3MPaG, Vd
Using a mixed gas of F / HFP / TFE (molar ratio 31:59:10) as a dispensing gas, the operation of injecting until the internal pressure becomes 1.4 MPaG until the solid content concentration in the produced latex becomes 25% by weight. I repeated it. As soon as the solid content reached a predetermined level, the reaction was stopped by purging the unreacted gas in the autoclave.

To a part of the obtained aqueous latex, 5% by weight potassium alum water was added to coagulate the formed terpolymer B,
Washed and dried. 1,700 g (polymerization rate: 75%) of a terpolymer fluororesin was obtained. The yield is the amount recovered when the total amount of the obtained aqueous latex is salted out, and the conversion is calculated based on the value.

The copolymer composition of this fluororesin (elemental analysis, F
(By T-IR) is VdF29 mol%, TFE57 mol%, HFP14 mol%
The melting point (by the DCS method) is 160 ° C, the heat of fusion (ΔH; by the DSC method) is 8.0 J / g, and the melt flow rate (at 265 ° C,
The load (5 kg) was 8.0.

Reference Example 3 10 g of ammonium perfluorooctanoate, 2 g of sodium hydroxide and 5 L of deionized water were charged into an autoclave having a volume of 10 L, and the internal space was sufficiently replaced with nitrogen gas. 14.98 g of iodoperfluorobutane was injected. Then, a mixed gas consisting of vinylidene fluoride [VdF] 22 mol%, tetrafluoroethylene [TFE] 8 mol%, hexafluoropropene [HFP] 70 mol% was injected until the internal pressure became 2.0 MPa · G, and the internal temperature was lowered. The temperature was raised to 70 ° C.

Thereafter, 5 g of ammonium persulfate was added to 150 ml of water.
The polymerization initiator aqueous solution dissolved in was poured into an autoclave to start the polymerization reaction. The internal pressure at this time is 3.2M
Pa · G. When the internal pressure drops to 2.9MPaG, Vd
Using a mixed gas of F / HFP / TFE (molar ratio 47:34:19) as a dispensing gas, press-inject until the internal pressure becomes 3.0 MPaG, until the solid content concentration in the produced latex becomes 30% by weight. I repeated it. As soon as the solid content reached a predetermined level, the reaction was stopped by purging unreacted gas in the autoclave.

To a part of the obtained aqueous latex, 5% by weight of potassium alum water was added to coagulate the resulting terpolymer,
Washed and dried. 1685 g of fluorine-containing copolymer C (conversion rate 50
%) Obtained, copolymer composition of this copolymer (by ¹⁹ F-NMR)
Is VdF / TFE / HFP = 54/20/26 (mol%), the iodine content (by elemental analysis) is 0.33 mmol / g, the glass transition temperature (by DSC method) is -10 ° C, and the solution viscosity ηsp / c (specific viscosity of 1% by weight MEK solution, 35 ° C.) was 0.58 dl / g.

Reference Example 4 In an autoclave having an internal volume of 10 L, 10 g of ammonium perfluorooctanoate, 2 g of sodium hydroxide and 5 L of deionized water were charged, and the internal space was sufficiently replaced with nitrogen gas. 7.65 g of iodoperfluorobutane was injected. Thereafter, a mixed gas containing 95 mol% of vinylidene fluoride [VdF] and 5 mol% of chlorotrifluoroethylene [CTFE] was injected until the internal pressure became 2.0 MPa · G, and the internal temperature was raised to 70 ° C.

Thereafter, 5 g of ammonium persulfate was added to 150 ml of water.
The polymerization initiator aqueous solution dissolved in was poured into an autoclave to start the polymerization reaction. The internal pressure at this time is 2.5M
Pa · G. When the internal pressure drops to 2.0MPaG, Vd
F / CTFE (molar ratio: 95: 5)
The press-in operation until the pressure became 2.1 MPa · G was repeated until the solid content concentration in the produced latex became 25% by weight. As soon as the solid content reached a predetermined level, the reaction was stopped by purging unreacted gas in the autoclave.

A portion of the obtained aqueous latex was added with 5% by weight of alum water to coagulate the resulting copolymer, washed with water and dried. 1680 g of fluorinated copolymer D (80% conversion)
The copolymer composition of this copolymer (by ¹⁹ F-NMR) is V
dF / CTFE = 92/8 (molar ratio), iodine content (by elemental analysis)
Is 0.020 mmol / g and the glass transition temperature (by DSC method) is
At 151 ° C., the solution viscosity ηsp / c (specific viscosity of a 1% by weight dimethylformamide solution, 35 ° C.) was 1.50 dl / g.

Example 1 100 parts by weight of fluorinated copolymer A MT carbon black 30 bisphenol AF 2 benzyltriphenylphosphonium chloride 0.5 calcium hydroxide 5 magnesium oxide 3 zinc oxide (1 kind; Sakai Chemical) 6.5 各 The above components are kneaded with an 8-inch mixing roll, and the kneaded material is press-crosslinked at 180 ° C for 10 minutes and 230 ° C,
Oven crosslinking (secondary crosslinking) was performed for 22 hours.

The following items were measured for the obtained crosslinked product. Crosslinking property: Time required to reach 90% torque value of minimum torque value (M _L ), maximum torque value (M _H ) and maximum torque value using ASTM-100 oscillating disk rheometer manufactured by Toyo Seiki ( tc ₉₀ ) Measured Normal properties: JIS K-6301 Compression set: P-24 O-ring, 200 ° C, 70 hours, 2
Measured under 5% compression conditions Engine oil resistance: Measured for normal properties after immersion in engine oil (TOYOTA Castle Motor Oil Clean SJ 10W-30) at 175 ° C for 70 hours

Example 2 In Example 1, the amount of zinc oxide was changed to 12 parts by weight.

Example 3 In Example 1, the same amount of zinc oxide (activated zinc white) was used in place of zinc oxide (one kind).

Example 4 In Example 1, the same amount of aluminum oxide was used in place of zinc oxide (one kind).

Example 5 In Example 1, the same amount of lead oxide was used in place of zinc oxide (one kind).

Example 6 A mixture of 85% by weight of the aqueous latex before coagulation of Reference Example 1 and 15% by weight of the aqueous latex before coagulation of Reference Example 2 was added with 5% by weight.
A potassium alum aqueous solution was added to co-coagulate, washed with water and dried to obtain a blended polymer A.

To 100 parts by weight of the blended polymer A, the respective components of Example 3 were added, and kneading, crosslinking, and measurement of each item were similarly performed.

Comparative Example 1 In Example 1, no zinc oxide was used.

Table 1 shows the measurement results in the above Examples and Comparative Examples. Table 1 Measurement Items Actual-1 Actual-2 Actual-3 Actual-4 Actual-5 Actual-6 Ratio-1 [Cross-linking property] Minimum torque value M _L (dNm) 1.6 1.8 1.8 1.7 1.7 2.1 1.4 Maximum torque value M _H (dNm) 24.7 25.9 25.0 25.1 25.3 26.2 23.5 Time to reach 90% torque value (min) 2.47 2.66 2.50 2.52 2.58 3.00 2.44 [Physical properties] Hardness (point) 76 78 75 77 76 79 74 100% modulus (MPa ) 5.8 6.4 6.0 5.6 5.7 7.8 7.8 5.2 Tensile strength (MPa) 14.0 13.5 13.8 13.5 12.9 15.7 13.9 Elongation (%) 190 180 190 180 170 200 200 [Compressive set] P-24 O-ring (%) 16 15 14 17 18 17 16 [Engine oil resistance] Hardness (point) 76 78 75 78 78 80 80 100% modulus (MPa)-3.3 3.2--5.0-Tensile strength (MPa) 6.0 6.9 7.0 5.8 6.0 7.8 4.6 Elongation (%) 90 120 140 80 90 150 60

Example 7 100 parts by weight of the fluororesin B obtained in Reference Example 2 and zinc oxide (1
Seed) and 3 parts by weight were kneaded with a 4 inch mixing roll heated to 100 ° C. The kneaded material obtained is converted into a small injection molding machine
Using (Custom Scientific Hook Instrument Model CS-183MNX), (plasticization condition 240 ° C, time 5
Injection molding was performed under the conditions of a mold temperature of 140 ° C. for 1 minute. The injection molded product was immersed in engine oil under the same conditions as in Example 1, but the molded product after immersion showed almost no coloring.

Comparative Example 2 When zinc oxide was not used in Example 7, the injection-molded product after immersion in engine oil had a brown color.

Example 8 A mixture of 85% by weight of the aqueous latex before coagulation of Reference Example 3 and 15% by weight of the aqueous latex before coagulation of Reference Example 4 was added with 5% by weight.
A potassium alum aqueous solution was added to co-coagulate, washed with water and dried to obtain a blended polymer B. Blend polymer B 100 parts by weight MT carbon black 30 亜 鉛 Zinc oxide (1 type) 12 〃 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane 0.5 〃 Triallyl isocyanurate 4 〃 Each component above Was kneaded with an 8-inch mixing roll, and the kneaded material was press-crosslinked at 180 ° C. for 5 minutes and 200 ° C.
Oven crosslinking (secondary crosslinking) was performed for a long time, and the same measurement as in Example 1 was performed on the obtained crosslinked product.

Comparative Example 3 In Example 8, no zinc oxide was used.

The results obtained in Example 8 and Comparative Example 3 are shown in Table 2 below. Table 2 Measurement items Example 8 Comparative example 3 [Crosslinking property] Minimum torque value M _L (dN · m) 0.8 0.6 Maximum torque value M _H (dN · m) 24.9 23.1 Time to reach 90% torque value (min) 1.52 1.59 [ Physical properties] Hardness (point) 77 74 100% modulus (MPa) 5.0 4.0 Tensile strength (MPa) 18.0 17.8 Elongation (%) 190 200 [Compressive permanent set] P-24 O-ring (%) 35 38 [Engine resistance] Oiliness] Hardness (point) 77 78 100% modulus (MPa) 2.2-Tensile strength (MPa) 7.2 4.7 Elongation (%) 140 90

From the above results, the following can be said. (1) From the comparison of Examples 1-2 and Comparative Example 1, as seen in the values of tensile strength and elongation due to the addition of zinc oxide, improvement in engine oil resistance was observed, and the effect of increasing the amount of zinc oxide It is also seen. When the amount of zinc oxide is the same, the greatest improvement effect is observed on activated zinc white (Example 3). Furthermore,
In addition to zinc oxide, the amphoteric oxides available as rubber compounding agents, such as alumina and lead oxide, also achieve the same effect of improving engine oil resistance as zinc oxide (Examples 4 and 5). (2) In Example 6, in which a fluorine-containing elastomer and a fluorine resin having a common cross-linking point were blended, and active zinc white was blended therein, not only the best engine oil resistance was exhibited, but also improvements in the physical properties in the normal state were achieved. There is a synergistic effect. (3) As can be seen from the comparison between Example 7 and Comparative Example 2, by adding zinc oxide, the colorability of the molded product after immersion in engine oil is also improved. (4) For peroxide-crosslinked fluororubber molded products,
The same result as that of the polyol-crosslinked fluororubber molded product was obtained.

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[Procedure amendment]

[Submission date] July 21, 2000 (2007.2)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

The above components are kneaded using a mixing roll, a kneader, a Banbury mixer, or the like to prepare a composition. The prepared composition is used for press molding machine, injection
Using a molding machine, transfer molding machine, etc., about 150-220
Cross-linking is performed by heating at about 0.5 to 10 minutes at about 150 ° C., and secondary crosslinking is performed at about 150 to 250 ° C. for about 1 to 20 hours as needed.

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Claims (8)

[Claims] 1. A rubber molded product comprising a crosslinked product of a fluororubber containing an amphoteric oxide and used for contact with engine oil. 2. The rubber molded product for use in contact with engine oil according to claim 1, wherein the fluororubber is a vinylidene fluoride-hexafluoropropene copolymer rubber. 3. The rubber molded product used for engine oil contact according to claim 1, wherein the fluororubber is a polyol crosslinkable rubber. 4. The rubber molded article used for engine oil contact according to claim 1, wherein the fluororubber is a peroxide crosslinkable rubber. 5. The rubber molded product for use in an engine oil contact according to claim 1, wherein the fluororubber is used as a blend with a fluororesin. 6. The rubber molded article used for engine oil contact according to claim 5, wherein both the fluororubber and the fluororesin constituting the blend are polyol crosslinkable. 7. The rubber molded product used for engine oil contact according to claim 5, wherein both the fluororubber and the fluororesin constituting the blend are peroxide crosslinkable. 8. The rubber molded product according to claim 1, wherein the rubber molded product is a sealing material.