Rubber-metal laminated gasket material

Abstract

A rubber-metal laminated gasket material in which a surface treatment agent layer, an adhesive layer, and a rubber layer are sequentially laminated on a metal plate, wherein the surface treatment agent layer is formed using a surface treatment agent containing an organic titanium compound and a titanium coupling agent-treated alumina, and the elemental mass ratio of titanium to aluminum in the surface treatment agent coating is 5:95 to 60:40. The rubber-metal laminated gasket material exhibits the following effects: no adhesive peeling occurs, for example, in a heat resistance test method in LLC under actual use environment of an engine cylinder head gasket, and also shows excellent resistance to LLC under high-temperature conditions of 150°C for 300 hours.

Description

Technical Field

[0001] The present invention relates to a rubber-metal laminated gasket material, and more particularly to a fluororubber-metal laminated gasket material suitable for use as a gasket for an engine cylinder head or the like. Background Art

[0002] Mild steel and stainless steel are the main metal materials used for engine cylinder head gaskets, which require resistance to water, LLC (Long-Life Coolant), and heat. However, even when these are directly bonded to rubber using a vulcanized adhesive, the durability of the liquid bond is poor. Immersion tests involving immersion of these rubber-metal laminates in water, LLC, and the like can cause adhesive peeling. This poor LLC resistance can lead to rubber peeling within the engine, potentially leading to engine failure.

[0003] To improve the adhesion between metal sheets and rubber, methods such as zinc phosphate treatment and iron phosphate treatment are used to treat the surface of stainless steel sheets. These methods involve immersing degreased steel sheets in an acidic solution to form an insoluble film on the steel sheet, ensuring rust prevention and adhesion to adhesives. However, these methods present problems such as the generation of sediment (industrial waste) during the film formation stage and the degradation of chemical reagent content due to the reaction, requiring frequent chemical injection and resulting in high costs.

[0004] As a pre-treatment for applying a vulcanized adhesive, the present applicant proposed applying a coating type chromate treatment on a stainless steel plate to improve resistance to water, LLC, etc. (Patent Documents 1-2). 6+ ions, so it is not ideal from an environmental perspective.

[0005] In addition, as a method that does not use zinc phosphate, iron phosphate, chromium, etc., a surface treatment agent containing organic resin, silica, titanium derived from fluoride, and zirconium oxide has been proposed. However, since it contains fluorine, it is necessary to remove fluorine from wastewater, which makes the equipment complicated (see Patent Document 3).

[0006] On the other hand, as an improvement to the above-mentioned surface treatment agent, a fluorine-free treatment agent has been proposed. However, when used in a severe environment such as a cylinder head gasket exposed to high-temperature LLC steam, sufficient adhesion cannot be obtained (Patent Document 4).

[0007] To address this issue, the present applicant proposed a rubber-metal laminated gasket material in Patent Document 5, which comprises a surface treatment agent layer, an adhesive layer, and a rubber layer laminated in sequence on a metal plate, wherein the surface treatment agent layer is coated with a surface treatment agent (the surface treatment agent does not contain chromium, has a mixing ratio of 20 to 90 weight percent of a fluorine-free titanium compound and 10 to 80 weight percent of aluminum oxide, and a titanium metal content of 1 to 20 weight percent) so that the coating amount on one side is 30 to 1000 mg / m 2 This rubber-metal laminated gasket material contains no chromium or fluorine and exhibits excellent LLC resistance under high-temperature conditions. Patent documents 6 and 7 also propose combining an organometallic compound containing a chelate structure with an inorganic filler such as alumina or silica as a primer for rubber-metal laminated gaskets. However, further improvement in LLC resistance under prolonged high-temperature conditions is needed.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-006307

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 11-221875

[0012] Patent Document 3: Japanese Patent No. 5,050,316

[0013] Patent Document 4: WO 2011 / 002040

[0014] Patent Document 5: WO 2014 / 208113

[0015] Patent Document 6: Japanese Patent Application Laid-Open No. 2005-180682

[0016] Patent Document 7: Japanese Patent Application Laid-Open No. 2006-218629

[0017] Patent Document 8: Japanese Patent Application Laid-Open No. 7-165953 Summary of the Invention

[0018] Technical problem to be solved by the invention

[0019] The present invention has been made in view of the above-mentioned problems, and provides a rubber-metal laminated gasket material having excellent LLC resistance under high temperature conditions.

[0020] Solutions to Problems

[0021] The above-mentioned object of the present invention is achieved by a rubber-metal laminated gasket material, in which a surface treatment agent layer, an adhesive layer and a rubber layer are laminated in sequence on a metal plate, wherein the surface treatment agent layer is formed using a surface treatment agent, and the surface treatment agent contains an organic titanium compound and titanium coupling agent treated aluminum oxide, and the elemental mass ratio of titanium to aluminum in the surface treatment agent film is 5:95 to 60:40.

[0022] Effects of the Invention

[0023] The rubber-metal laminated gasket material of the present invention exhibits the following effects: For example, it exhibits excellent LLC resistance even under high-temperature conditions of 150°C for 300 hours, without causing adhesive delamination in LLC heat resistance tests, which are based on the actual usage environment of engine cylinder head gaskets. Specifically, the material exhibits the following excellent effects: in the combination of an organometallic compound and an inorganic filler, treating the alumina surface with a coupling agent improves the LLC resistance of the primer. This improved LLC adhesion eliminates rubber delamination in engine gaskets, thereby improving the problem.

[0024] In addition, since the surface treatment agent does not contain chromium and fluorine, it is preferred from an environmental perspective. In addition, since it is fluorine-free, there is no need to remove fluorine from wastewater. Moreover, the surface treatment does not form a film through a chemical reaction with the stainless steel plate like zinc phosphate treatment, but is formed by simply applying a prepared chemical reagent, so the formation of deposits is completely invisible. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the scores of the peeling state after the drawing test performed in Examples and Comparative Examples. DETAILED DESCRIPTION

[0026] Metal plates can be used, for example, mild steel, stainless steel, aluminum, and aluminum die-cast plates. Stainless steel plates such as SUS301, SUS301H, SUS304, and SUS430 can be used. Since these are gaskets, metal plates with a thickness of approximately 0.1 to 2 mm are typically used. These metal plates are coated with a surface treatment agent containing an organic titanium compound and aluminum oxide surface-treated with a titanium coupling agent. The metal plates are preferably roughened and then alkaline degreased before use.

[0027] The surface treatment agent used is one in which the elemental mass ratio of titanium to aluminum in the surface treatment agent film is 5:95 to 60:40, preferably 6:94 to 30:70. If the elemental mass ratio is other than the above ratio, as shown in the comparative example described below, delamination occurs in the portion exposed to LLC vapor after immersion in LLC at 150°C for 300 hours.

[0028] As the organic titanium compound, there can be mentioned alkoxytitanium, titanium acylate or titanium chelate containing a Ti-OC bond formed by Ti(IV) or Ti(III) and a compound having an alcoholic hydroxyl group, a phenolic hydroxyl group or a carboxyl group. For example, tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, and an organic titanium compound composed of a chelate ring and an alkoxy group represented by the following general formula can be used. Specifically, organic titanium compounds such as isopropoxytitanium bis(ethylacetoacetate), 1,3-propanedioxytitanium bis(ethylacetoacetate), diisopropoxybis(acetylacetonate)titanium, and tetra(acetylacetonate)titanium can be used. Commercially available products such as tetra-n-butyl titanate manufactured by Mitsubishi Gas Chemical Co., Ltd., and Orgatix TA-10, Orgatix TA-21, Orgatix TA-23, Orgatix TA-30, and Orgatix TC-100 manufactured by Matsumoto Fine Chemical Co., Ltd. may be used as the above-mentioned compounds.

[0029]

[0030] R: CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, etc.

[0031] Lower alkyl group with 1 to 5 carbon atoms

[0032] n: integer from 1 to 4

[0033] As the aluminum oxide that has been surface-treated with a titanium coupling agent, a product in which the surface of the aluminum oxide has been treated with a titanium coupling agent can be used. In fact, a commercially available product such as Matsumoto Fine Chemical Co., Ltd., product TC-500 (titanium diethanolaminate) can be used directly. The particle size of the aluminum oxide used herein is not particularly limited. By performing this surface treatment, the functional groups on the surface of the aluminum oxide are reduced, the reaction between the aluminum oxide and the organometallic compound is suppressed, and the reaction points between the organometallic compound and the metal steel plate can be increased. Here, in the case of using aluminum oxide that has not been surface-treated, the functional groups on the surface of the aluminum oxide react with the organometallic compound, hindering the adhesion between the organometallic compound and the stainless steel plate. On the other hand, in the case of not using aluminum oxide, the liquid shielding property of the primer is reduced, and when in contact with water or LLC, a potential is generated between the engine block / cylinder head made of aluminum and the stainless steel plate of CHG, promoting peeling.

[0034] The above components are used as essential components, and are mixed, dissolved, and dispersed in a solvent to prepare a surface treatment agent. The surface treatment agent is applied by dipping, spraying, brushing, roller coating, etc. at a concentration of 30 to 2500 mg / m 2 , preferably 500-1500 mg / m 2 The single-sided coating amount (weight per unit area) of is applied on the surface of both sides of the metal plate, dried at room temperature or under hot air, and then baked at 100 to 250°C for 1 to 20 minutes. When the coating amount is greater than this, peeling occurs at the portion immersed in the LLC liquid. On the other hand, when the coating amount is less than this, the adhesion between the metal and the rubber is reduced. It should be noted that the solvent for dissolving and dispersing the organic titanium compound and the titanium coupling-treated alumina is not particularly limited, and for example, methanol or the like can be used.

[0035] A resin-based vulcanized adhesive, such as a thermosetting phenolic resin or epoxy resin, is applied as a rubber adhesive to the surface treatment agent layer applied to the metal plate and dried. The thermosetting phenolic resin can be any of cresol novolac-type phenolic resins, cresol resol-type phenolic resins, and alkyl-modified phenolic resins. Furthermore, the epoxy resin is preferably a cresol novolac-type epoxy resin. In this case, a bisphenol novolac-type phenolic resin is used as a curing agent. Furthermore, an imidazole compound can be used as a curing catalyst. For example, an epoxy resin-based vulcanized adhesive comprising an epoxy resin and an imidazole curing agent mixed in a ratio of 9.5:0.5 to 7:3 can be used.

[0036] These resin-based vulcanized adhesives are usually prepared by using an alcohol organic solvent such as methanol, ethanol, isopropyl alcohol or a ketone organic solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone as a single solvent or a mixed solvent to prepare an organic solvent solution having a component concentration of about 1 to 5% by weight, and are applied by the same coating method as the surface treatment agent at a rate of 100 to 2500 mg / m 2 The single-sided unit area weight (coating amount) is coated, dried at room temperature or with hot air, and then baked at 100 to 250° C. for 1 to 20 minutes.

[0037] On the vulcanized adhesive layer thus formed, an unvulcanized rubber compound is applied in the form of an organic solvent solution of a rubber compound to form a sulfide layer with a single-sided thickness of about 5 to 120 μm on both sides of the vulcanized adhesive layer. The rubber compound is prepared by mixing using a mixing machine such as an intermix, a kneader, or a Banbury mixer, or an open roller, to prepare a rubber paste coating liquid with a solid content concentration of about 20 to 50% by weight. As the rubber, fluororubber, nitrile rubber, etc. can be used, and fluororubber is preferably used.

[0038] As the fluororubber, either polyol-vulcanizable or peroxide-vulcanizable fluororubber can be used.

[0039] Examples of polyol-vulcanizable fluororubbers generally include copolymers of vinylidene fluoride and at least one of other fluorinated olefins, such as hexafluoropropylene, pentafluoropropylene, tetrafluoroethylene, chlorotrifluoroethylene, fluorinated vinyl, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), or copolymers of these fluorinated olefins with propylene. These fluororubbers can be polyol-vulcanized using polyhydroxy aromatic compounds such as 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)perfluoropropane, and hydroquinone.

[0040] In addition, as peroxide-curable fluororubber, for example, fluororubber having iodine and / or bromine in the molecule can be cited, and these fluororubbers are generally vulcanized (crosslinked) by the organic peroxide used in peroxide vulcanization. In this case, it is preferred that the organic peroxide is used together with a polyfunctional unsaturated compound represented by triallyl isocyanurate.

[0041] As an unvulcanized fluororubber compound, for example, the following compounding examples are shown.

[0042] (Match Example I)

[0043]

[0044]

[0045] (Match Example II)

[0046]

[0047] (Match Example III)

[0048]

[0049] (Match Example IV)

[0050]

[0051] In addition, as acrylonitrile-butadiene rubber (NBR), also can use with the form of rubber compound (having used sulfur-based vulcanizing agents such as sulfur, tetramethylthiuram monosulfide, tetramethylthiuram disulfide), preferably use with the form of the unvulcanized acrylonitrile-butadiene rubber compound that uses organic peroxide as crosslinking agent.As the unvulcanized acrylonitrile-butadiene rubber compound of described peroxide crosslinking link, for example, illustrate following coordination example.

[0052] (Combination Example V)

[0053]

[0054] (Match Example VI)

[0055]

[0056] The applied unvulcanized rubber layer is dried at a temperature between room temperature and about 100°C for about 1 to 15 minutes, and the organic solvents such as methanol, ethanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, aromatic hydrocarbons such as toluene, xylene, or mixed solvents thereof are evaporated. The layer is then heated and vulcanized at about 150 to 230°C for about 0.5 to 30 minutes. Press vulcanization can also be performed as needed. For use as a gasket, the vulcanized rubber layer preferably has a hardness (durometer A) of 80 or more and a compression set (100°C, 22 hours) of 50% or less. As long as the desired properties are met, the composition is not particularly limited. Furthermore, if anti-sticking is required, an anti-sticking agent can be applied to the surface.

[0057] Anti-sticking agents are used to prevent adhesion between rubbers and between rubber and metal. As long as a film can be formed on the vulcanized rubber layer, any anti-sticking agent can be used. For example, silicone-based, fluorine-based, graphite-based, amide, wax-based such as paraffin, polyolefin-based or polybutadiene-based anti-sticking agents can be mentioned. It is preferred to use an anti-sticking agent that contains a liquid organic solvent dispersion of 1,2-polybutadiene hydroxyl group-containing material, 1,2-polybutadiene isocyanate group-containing material and polyolefin-based resin, such as a rubber paste coating liquid in which wax and graphite are dispersed in a ratio of 9:1 to 5:9 (Patent Document 8).

[0058] [Example]

[0059] Next, the present invention will be described in detail with reference to Examples. However, the present invention, including its effects, is not limited to these Examples.

[0060] Example 1

[0061] Alkaline degreased SUS301 stainless steel plate (thickness 0.2mm) was coated with a surface treatment agent so that the weight per unit area on one side was 700mg / m 2 , and baked at 200°C for 10 minutes to form a primer layer. The surface treatment agent used titanium acetylacetonate (Matsumoto Fine Chemical Co., Ltd. product Orgatix TC-100; (i-C3H7O)2Ti(C6H9O3)2) and titanium coupling agent treated alumina (Matsumoto Fine Chemical Co., Ltd. product Orgatix TC-500), and the element mass ratios of Ti and Al in the surface treatment agent film were adjusted to 8 wt% and 92 wt%, respectively.

[0062] On the steel plate coated with the surface treatment agent, an epoxy resin-based vulcanized adhesive was applied to a coating weight of 300 mg / m 2After air drying, the epoxy resin vulcanized adhesive was calcined at 200°C for 5 minutes. The epoxy resin vulcanized adhesive was mixed with epoxy resin (Nippon Steel Chemical & Material Co., Ltd. product YDCN-700-7) and imidazole curing agent (Shikoku Chemical product Curezol2E4MZ-CN) in a ratio of 8:2.

[0063] A 25 wt% methyl isobutyl ketone-methanol (weight ratio 8:2) mixed solvent solution of the fluororubber compound of the above-mentioned formulation example I was applied to the vulcanized adhesive-coated steel plate, dried at 60°C for 15 minutes to form an unvulcanized rubber layer with a single-side thickness of 20 μm, and then vulcanized at 200°C for 5 minutes. The plate was then coated with a rubber paste coating liquid in which wax (Mitsui Chemicals product 4202E) and graphite (Oriental Sangyo Co., Ltd. product AT-No.40) were dispersed in a ratio of 8:2, and baked at 200°C for 5 minutes to form an anti-sticking layer to produce a fluororubber-metal laminated gasket material.

[0064] Example 2

[0065] In Example 1, titanium acetylacetonate and a titanium coupling agent were used to treat alumina so that the element mass ratios of Ti and Al in the surface treatment agent film were adjusted to 23 wt % and 77 wt %, respectively.

[0066] Example 3

[0067] In Example 1, titanium acetylacetonate and a titanium coupling agent were used to treat alumina so that the element mass ratios of Ti and Al in the surface treatment agent film were adjusted to 46 wt % and 54 wt %, respectively.

[0068] Example 4

[0069] In Example 1, tetraoctyl titanate (Orgatix TA-30, a product of Matsumoto Fine Chemical Co., Ltd.; Ti[OCH2CH(C2H5)C4H9]4) was used instead of titanium acetylacetonate, and alumina was treated with tetraoctyl titanate and a titanium coupling agent to adjust the elemental mass ratios of Ti and Al in the surface treatment agent film to 33 wt% and 67 wt%, respectively.

[0070] Comparative Example 1

[0071] In Example 1, untreated alumina (Denka ASFP-20) was used instead of titanium coupling agent treated alumina, and titanium acetylacetonate and alumina were used to adjust the elemental mass ratios of Ti and Al in the surface treatment agent film to 17 wt% and 83 wt%, respectively.

[0072] Comparative Example 2

[0073] In Example 1, titanium acetylacetonate and a titanium coupling agent were used to treat alumina so that the element mass ratios of Ti and Al in the surface treatment agent film were adjusted to 72 wt % and 28 wt %, respectively.

[0074] Comparative Example 3

[0075] In Example 1, titanium acetylacetonate was not used, but a titanium coupling agent was used to treat alumina, and the element mass ratio of Al in the surface treatment agent film was 100 wt%.

[0076] Comparative Example 4

[0077] In Example 1, a silane coupling agent (Z6011, manufactured by Dow Corning Toray Co., Ltd.) was used instead of titanium acetylacetonate, and the alumina was treated with the silane coupling agent and the titanium coupling agent to adjust the elemental mass ratios of Si and Al in the surface treatment agent film to 25 wt % and 65 wt %, respectively.

[0078] The rubber-metal laminated gasket materials obtained in the above examples and comparative examples were evaluated for their adhesion under high-temperature LLC conditions.

[0079] Adhesion evaluation: In a pressure-resistant container, the lower half of the rubber-metal laminated gasket material in the vertical direction is immersed in an impregnation liquid [LLC (Toyota's long-life coolant): water = volume ratio 50:50] and placed at 150°C for 300 hours. According to JIS K6894, the lower impregnated part immersed in the impregnation liquid and the upper exposed part (non-impregnated part) exposed to LLC vapor above the impregnation liquid are subjected to a drawing test as shown in FIG. Figure 1 Evaluate as shown.

[0080] 4 points or above, pass

[0081] The obtained results are shown in the following table.

[0082] surface

[0083]

[0084] Based on the above results, the summary is as follows.

[0085] (1) In each example, a rubber-metal laminated gasket material having excellent LLC resistance under high temperature conditions was obtained.

[0086] (2) When the surface treatment agent used is alumina treated with an organic titanium compound and a titanium coupling agent in amounts outside the prescribed range, the adhesion is low in the upper exposed portion (non-impregnated portion) above the LLC impregnation liquid that is exposed to LLC vapor, and the cylinder head gasket cannot withstand the use in the actual use environment of the engine (Comparative Examples 1-2).

[0087] (3) When using alumina that has not been surface-treated with a titanium coupling agent, the functional groups on the surface of the alumina react with the organometallic compound, hindering the adhesion between the organometallic compound and the stainless steel plate. Therefore, the upper exposed part (non-impregnated part) of the LLC immersion liquid exposed to the LLC vapor has low adhesion (Comparative Example 3).

[0088] Industrial applicability

[0089] The rubber-metal laminated gasket material of the present invention is excellent in LLC resistance under high temperature conditions and can therefore be effectively used as a gasket for an engine cylinder head or the like.

Claims

1. A rubber-metal laminated gasket material, comprising a surface treatment agent layer, an adhesive layer, and a rubber layer laminated sequentially on a metal plate, wherein: The surface treatment agent layer is formed using a surface treatment agent. The surface treatment agent contains an organic titanium compound and titanium coupling agent treated aluminum oxide, and the element mass ratio of titanium to aluminum in the surface treatment agent film is 5:95 to 60:

40.

2. The rubber-metal laminate gasket material according to claim 1, wherein: The organic titanium compound is titanium alkoxide or titanium chelate.

3. The rubber-metal laminated gasket material according to claim 1, wherein: The organic titanium compound is tetraoctyl titanate or titanium acetylacetonate.

4. The rubber-metal laminated gasket material according to claim 1, wherein: The adhesive is an epoxy resin adhesive.

5. The rubber-metal laminated gasket material according to claim 1, wherein: The rubber is fluororubber.

6. The rubber-metal laminate gasket material according to claim 1, wherein: A release layer is formed on the rubber layer.

7. The rubber-metal laminate gasket material according to claim 1, which is used as a gasket for an engine cylinder head.

8. A gasket for an engine cylinder head, produced from the rubber-metal laminated gasket material according to claim 7.

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