JP2005249031A - Rubber-metal laminated gasket raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber-metal laminated raw material, having excellent LLC resistance and heat resistance without conducting harmful coating type chromate filming to metal in forming the rubber-metal laminated gasket raw material made of a complex of stainless steel plate and rubber, and not causing separation of adhesion, for example, in a LLC resistance testing method taking into consideration the environment for actually using a metal gasket for an engine. <P>SOLUTION: In this rubber-metal laminated gasket raw material, an undercoat treatment agent layer containing (a) a silane coupling agent, (b) an organometal compound and (c) silica, a vulcanized adhesive layer containing phenol resin and a rubber layer are sequentially laminated on a stainless steel plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber-metal laminated gasket material. More specifically, the present invention relates to a rubber-metal laminated gasket material that is suitably used as a metal gasket for engines.

  Rubber-coated stainless steel sheets, in which a rubber layer is laminated on stainless steel sheets, are commonly used as gaskets for automobile engines, such as metal gasket materials for engines that require water resistance, LLC (long life coolant) resistance, and heat resistance. Has been used. However, even if a vulcanized adhesive is applied directly to stainless steel and bonded to rubber, the liquid-resistant adhesion durability is poor, and when this rubber metal laminate is subjected to a dip test in water, LLC, etc., adhesive peeling will occur. become.

As a countermeasure for this, a gasket material is generally known in which a chromate film made of Cr compound, phosphoric acid, Si, or the like is formed on one or both surfaces of a stainless steel plate, and a rubber layer is laminated on the chromate film. Such a gasket material is excellent in so-called antifreeze liquid resistance, in which the adhesiveness does not deteriorate even when used for a long period of time in an environment in contact with heat resistance or antifreeze liquid, and has been used for a wide range of applications. The present applicant has also proposed that as a pretreatment for applying a vulcanized adhesive, an application-type chromate treatment is performed on stainless steel to improve resistance to water, LLC, and the like.
JP 2000-006307 A Japanese Patent Laid-Open No. 11-221875

However, the coating-type chromate treatment is not preferable from the viewpoint of environmental measures because it contains Cr ⁶⁺ ions. In other words, hexavalent chromium has the drawback of having a direct adverse effect on the human body, and the waste liquid containing hexavalent chromium must be subjected to a special treatment stipulated in the Water Pollution Control Law. The waste of stainless steel material applied cannot be recycled. Furthermore, it is highly possible that chromium in the chromate film is extracted by contact with antifreeze or oil.

  On the other hand, undercoats for various vulcanized adhesives based on phenolic resins are also commercially available, but do not exhibit sufficient adhesion and water resistance in bonding with stainless steel.

Therefore, the present applicant has further proposed various vulcanized adhesive compositions based on alkoxysilane as an adhesive between metal and rubber in producing a rubber-metal laminated gasket material. These vulcanized adhesive compositions are particularly suitable for bonding to metal surfaces that have been previously chemically or physically surface treated, but when applied to untreated metal surfaces, for example, coating chromate treatment. It is not possible to obtain the same adhesion as in the case of stainless steel subjected to.
JP 7-34054 A JP 7-216309 A Japanese Patent Laid-Open No. 9-40916 JP-A-9-132758 Japanese Patent Laid-Open No. 10-7990 Japanese Patent Laid-Open No. 10-8021 JP 2001-226642 A

Further, as a chromeless gasket, Patent Document 10 discloses a metal gasket material in which a primer layer of a silica-alumina condensate is formed on the surface of a stainless steel plate, and Patent Document 11 discloses an acid gasket on one or both surfaces of a steel plate. Gasket materials with coatings made of bisphenol A novolak polymers with components, silica, titanium compounds and water-soluble nitrogen-containing substituents have been proposed, but they are used especially for water-related applications such as automobile engines Then, at the time of long-term use, peeling is likely to occur at the wetted part adhesion interface, and the current performance has not yet obtained the same performance as a coating type chromate treatment type gasket.
JP 2003-028307 A JP 2003-105321 A

  Accordingly, there is a demand for a gasket that has heat resistance and adhesion equivalent to or better than those of a coating type chromate treatment gasket, and also has durability against water and antifreeze liquid, and has no environmental problems.

  The object of the present invention is excellent in LLC resistance and heat resistance without forming harmful coating type chromate treatment on the metal when forming a rubber-metal laminated gasket material composed of a composite of a stainless steel plate and rubber. The purpose of the present invention is to provide a rubber-metal laminated gasket material in which adhesion peeling does not occur even in the LLC resistance test method considering the actual use environment of engine metal gaskets.

  The object of the present invention is to provide (a) a silane coupling agent, (b) an organometallic compound and (c) a base treatment agent layer containing silica, a phenol resin-containing vulcanized adhesive layer and a rubber layer on a stainless steel plate. This is achieved by a rubber-metal laminated gasket material obtained by sequentially laminating layers.

  The rubber-metal laminated gasket material according to the present invention comprises a stainless steel plate, (a) a silane coupling agent, (b) an organometallic compound and (c) a base treatment agent layer containing silica, and a phenol resin-containing vulcanized adhesive layer. In addition, by having a laminated structure composed of a rubber layer, it not only exhibits excellent liquid resistance against LLC liquid, but also has excellent heat resistance.

  As the stainless steel plate, SUS301, SUS301H, SUS304, SUS430, or the like is used. Since the plate thickness is used for gaskets, a thickness of about 0.1 to 2 mm is generally used. On these stainless steel plates, first, a base treatment agent containing (a) a silane coupling agent, (b) an organometallic compound and (c) silica is applied.

As the silane coupling agent of the component (a), the general formula (RO) _n SiX _4-n (where R is a lower alkyl group such as a methyl group or an ethyl group, and X is a methyl group or an ethyl group) Lower alkyl group, 3-aminopropyl group, aminoalkyl group such as N- (2-aminoethyl) -3-aminopropyl group, N-phenyl-3-aminopropyl group, vinyl group, 3-methacryloxypropyl group, etc. A methacryloxyalkyl group, a glycidoxyalkyl group such as 3-glycidoxypropyl group, a mercaptoalkyl group such as 3-mercaptopropyl group, etc., and n is 1 to 3, preferably 3. Organoalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycol Alone or as a mixture or hydrolyzate thereof or a partial condensate of such de propyl methyl diethoxy silane can be used. The hydrolysis reaction or partial condensation reaction is performed by reacting at least about 40 to 80 ° C. with an equivalent amount of water to the alkoxysilane group in the organoalkoxysilane.

  As such a silane coupling agent, a copolymer oligomer of an amino group-containing alkoxysilane and a vinyl group-containing alkoxysilane is preferably used.

  Examples of the amino group-containing alkoxysilane that is one component of the copolymer oligomer include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane. N-β- (aminoethyl) -γ-aminopropyltriethoxysilane and the like are used. When these amino group-containing alkoxysilanes are used as they are as one component of the vulcanized adhesive composition, the film formation cannot be performed well and a good vulcanized adhesive cannot be provided. As a copolymerized oligomer.

  As the vinyl group-containing alkoxysilane which is another component, for example, vinyltrimethoxysilane, vinyltriethoxysilane or the like is used. These vinyl group-containing alkoxysilanes are hardly soluble in water, become oily and separate, and cannot be mixed with other components. Moreover, since the oligomer is also hardly soluble in water and precipitates, it is used as an oligomer with an amino group-containing alkoxysilane.

  In the oligomerization reaction, 25 to 400 parts by weight, preferably 50 to 150 parts by weight of vinyl group-containing alkoxysilane and 20 to 150 parts by weight of water for hydrolysis are used with respect to 100 parts by weight of amino group-containing alkoxysilane. . If the vinyl group-containing alkoxysilane is used in a larger proportion, the compatibility with the rubber (or vulcanized adhesive) is deteriorated and the adhesiveness is lowered. On the other hand, if it is used in a smaller proportion, the water resistance is increased. Sexuality begins to decline.

  In the oligomerization reaction, these are charged into a reactor having a distillation apparatus and a stirrer, and stirred at about 60 ° C. for about 1 hour. Thereafter, an acid such as formic acid or acetic acid is added within 1 hour to about 1 to 2 moles per mole of amino group-containing alkoxysilane. The temperature at this time is kept at about 65 ° C. The mixture is further stirred for 1 to 5 hours to allow the reaction to proceed, and at the same time, the alcohol produced by hydrolysis is distilled under reduced pressure. Distillation is terminated when only distilled water is present, and then diluted and adjusted such that the silane concentration is 30 to 80% by weight, whereby the desired copolymer oligomer is obtained. This copolymer oligomer is an oligomer having a degree soluble in an alcohol-based organic solvent such as methanol or ethanol. Moreover, what is already marketed as a copolymerization oligomer or a primer can also be used as it is.

R：CH₃、C₂H₅、n-C₃H₇ 、i-C₃H₇、n-C₄H₉、i-C₄H₉などの低級アルキ
ル基
R´：CH₃基またはOR
M₁：Ti、Zr、Sn
M₂：Al
n：1〜3の整数
m：1〜2の整数
で表されるキレート環およびアルコキシ基から構成される有機金属化合物、好ましくは有機チタン化合物、有機ジルコニウム化合物、さらに好ましくは有機チタン化合物が用いられる。 Examples of the organometallic compound (b) include tetraisopropoxy titanium, tetra n-butoxy titanium, diisopropoxy titanium bis (ethyl acetoacetate), 1,3-propanedioxytitanium bis (ethyl acetoacetate), diisopropoxy Organic titanium compounds such as titanium bis (acetylacetonate), titanium tetraacetylacetonate, organic zirconium compounds such as tetra n-propylzirconium, tetra n-butoxyzirconium, di-n-butoxyzirconium bis (acetylacetonate), di-n- Organotin compounds such as butoxyzirconium bis (ethylacetoacetate), diisopropoxyzirconium bis (acetylacetonate), dibutyltin dilaurate, dibutyltin dioctate, dioctyltin dilaurate, triisopropoxyaluminium , Mono-sec-butoxydipropoxyaluminum, tri-sec-butoxyaluminum, ethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), monoisopropoxyaluminum bis (acetylacetonate), aluminum monoacetylacetonate bis And organic aluminum compounds such as ethyl acetoacetate and aluminum tris (acetylacetate).

R: Lower alkyl such as CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , iC ₃ H ₇ , nC ₄ H ₉ , iC ₄ H ₉
Le group
R´: CH ₃ group or OR
M ₁ : Ti, Zr, Sn
M ₂ : Al
n: Integer from 1 to 3
m: An organic metal compound composed of a chelate ring represented by an integer of 1 to 2 and an alkoxy group, preferably an organic titanium compound, an organic zirconium compound, and more preferably an organic titanium compound.

  The organometallic compound is used in a weight ratio of 2 to 15, preferably 2 to 10, with respect to the silane coupling agent. The organometallic compound contributes to the adhesion and adhesion to the steel sheet, and improves the balance between the liquid resistance and the heat resistance by setting the mixing ratio. When the organometallic compound is used in a larger proportion, the heat resistance is lowered. On the other hand, when the organometallic compound is used in a smaller proportion, the water resistance and the LLC resistance are lowered.

  Examples of the component (c) silica include colloidal silica, gas phase silica, and organosilica sol. From the viewpoint of dispersibility in the treatment liquid used, organosilica sol is preferably used. Examples of organosilica sols include commercially available methanol silica sol (Nissan Chemical Industries product: dispersed in methanol), Snowtex IPA-ST (manufactured by the company; dispersed in isopropyl alcohol), Snowtex EG-ST ( Company products: dispersed in ethylene glycol), Snowtex MEK-ST (company products: dispersed in methyl ethyl ketone), Snowtex MIBK-ST (company products: dispersed in methyl isobutyl ketone), etc. It is done. Examples of colloidal silica include commercially available products such as Snowtex C (Company product), Snowtex O (Company product), Snowtex N (Company product), Snowtex S (Company product), Snowtex UP (Company product), Snowtex PS-M (Company product), Snowtex PS-L (Company product), Snowtex 20 (Company product), Snowtex 30 (Company product), Snowtex 40 (Company product), etc. are used. Gas phase silica includes, for example, commercially available Aerosil 50 (Japan Aerosil product), Aerosil 130 (Company product), Aerosil 200 (Company product), Aerosil 300 (Company product), Aerosil 380 (Company product), Aerosil TT600 (Company product), Aerosil MOX80 (Company product), Aerosil MOX170 (Company product), etc. are used.

  Silica is used as an organic solvent solution such as alcohols such as methanol, ethanol and isopropanol, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone so that the solid content concentration is about 5 to 30% by weight. It is added in a proportion of 5 to 50% by weight, preferably 10 to 30% by weight in the solid component in the treatment agent. By adding silica, the adhesion between the base treatment agent layer and the vulcanized adhesive layer becomes stronger. When silica is used in a proportion higher than 50% by weight, the heat resistance is lowered, and adhesion peeling occurs in the bending test after heating with high temperature air. On the other hand, when silica is not used, the liquid durability against water, LLC and the like deteriorates.

  The above-mentioned surface treatment agent containing each component as an essential component is applied on a stainless steel plate subjected to alkali degreasing treatment to a thickness of 0.03 to 5 μm by a method such as immersion, spraying, brush printing, roll coating, etc. After being dried with wind, it is baked at 100-250 ° C. for 1-20 minutes.

  A phenol resin-containing vulcanized adhesive, preferably a phenol resin-containing vulcanized adhesive to which silica is added, is applied onto a base treatment agent layer that has been applied to a stainless steel plate and dried. As the phenolic resin-containing vulcanized adhesive, commercially available products such as Toyo Chemical Laboratory product METALOC N-31, Rohm and Haas product Sixon 715-A / B, Lord Far East product TS1677-13, etc. can be used. However, those in which a novolak phenol resin and a resole phenol resin are blended in a ratio of 9: 1 to 1: 9, and more preferably, those adhesives containing silica are used. Examples of the silica to be added to the adhesive include colloidal silica, gas phase silica, organosilica sol, etc., similar to the base treatment agent, and 60% by weight or less, preferably 20 to less than the total of the phenol resin, silica and other additive components. 50% by weight is blended. Silica in the adhesive is bonded to the silane coupling agent or silica in the surface treatment agent, thereby making the adhesion between the surface treatment agent layer and the vulcanized adhesive layer stronger. It is preferable to add both to the vulcanized adhesive. However, as shown in Example 5 and Comparative Example 2 below, even if only the base treatment agent is added, the effect of improving the adhesive force can be obtained.

  In the vulcanized adhesive, a rubber polymer such as nitrile rubber, fluororubber, and chlorinated rubber, or a resin component can be blended. The rubber polymer is blended and used at a ratio of 30% by weight or less in the total amount of the phenol resin, silica and other additive components. The rubber polymer or the like is blended alone or as a rubber compound.

  These phenolic resin-containing vulcanized adhesives generally have an alcohol organic solvent such as methanol, ethanol and isopropanol, or a ketone organic solvent such as acetone, methyl ethyl ketone and methyl isobutyl ketone, either alone or as a mixed solvent, with a component concentration of about 0.1. Prepared as a 10% by weight organic solvent solution, coated with a film thickness of 0.1-20 μm by the same coating method as in the case of the surface treatment agent, dried at room temperature or warm air, and then heated at 100-250 ° C. Bake for 20 minutes.

On the vulcanized adhesive layer formed in this way, an organic solvent for the rubber compound is formed so that the unvulcanized rubber compound forms a vulcanized layer having a thickness of about 5 to 120 μm on one side. It is applied as a solution. As the rubber material, (hydrogenated) nitrile rubber, fluorine rubber, acrylic rubber, ethylene propylene copolymer rubber, and the like are used, and nitrile rubber is preferably used. The nitrile rubber can be used as a compound using a sulfur vulcanizing agent such as sulfur or tetramethylthiuram monosulfide, but preferably as an unvulcanized nitrile rubber compound using an organic peroxide as a crosslinking agent. Used. Examples of such peroxide-crosslinked unvulcanized nitrile rubber compounds include the following blending examples.
(Examples of nitrile rubber compound)
NBR (JSR product N237) 100 parts by weight
HAF carbon black 80 〃
Powdered silica 60 〃
Zinc oxide 5 〃
Stearic acid 1 〃
Anti-aging agent (Ouchi Emerging Chemicals ODA-NS) 1 〃
Organic peroxide (NIPPON OIL & PRODUCTS PERHEXA 25B) 6 〃
N, Nm-Phenylenedimaleimide 1 〃

  The applied unvulcanized rubber layer is dried at a temperature of room temperature to about 100 ° C. for about 1 to 15 minutes, and alcohols such as methanol and ethanol used as an organic solvent, and ketones such as methyl ethyl ketone and methyl isobutyl ketone After volatilizing aromatic hydrocarbons such as toluene and xylene or a mixed solvent thereof, heat vulcanize at about 150 to 230 ° C for about 0.5 to 30 minutes, and pressurize and vulcanize as necessary. Is also done. The vulcanized nitrile rubber layer preferably has a hardness (durometer A) of 80 or more and a compression set (100 ° C., 22 hours) of 50% or less for use as a gasket, and needs to prevent adhesion. In some cases, an anti-sticking agent can be applied to the surface.

The anti-tacking agent is used for the purpose of preventing sticking between rubbers or between rubber and metal, and any anti-tacking agent can be used as long as it can form a film on the vulcanized nitrile rubber layer. , Fluorine-based, graphite-based, amide, paraffin-based wax-based, polyolefin-based or polybutadiene-based materials, etc., preferably liquid 1,2-polybutadiene hydroxyl group-containing materials, 1,2-polybutadiene isocyanate group-containing materials And an anti-adhesive agent comprising an organic solvent dispersion of polyolefin resin.
Japanese Patent Laid-Open No. 7-165953

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

Example 1
After alkali degreasing the surface of SUS301 steel plate (thickness 0.2mm),
Silane coupling agent primer 100 parts by weight (5)
(Japan Unicar product APZ6633, 5 wt% ethanol solution)
Tetra-n-butoxy titanium 40 〃
Organosilica sol (Nissan Chemical Products Snowtex MEK-ST; 50 〃 (15)
(Methyl ethyl ketone dispersion type, solid content concentration 30% by weight)
Methanol 5810 〃
A base treatment agent comprising the above was applied by a dipping method so as to have a film thickness of 0.1 μm, dried at 80 ° C., and then baked at 220 ° C. for 3 minutes. The parenthesis indicates the solid content weight.

next,
Phenol resin adhesive (Toyo Chemical Research product Metalolc N-31) 12 parts by weight Hexamethylenetetramine-containing curing agent (Company product Hexa-B) 0.4 〃
Organosilica sol (Snowtex MEK-ST) 4 〃
Methyl ethyl ketone 83.6 〃
The resulting vulcanized adhesive was applied by dipping to a thickness of 0.5 μm, dried at 80 ° C., and then baked at 200 ° C. for 3 minutes.

On this adhesive layer, a 25% by weight toluene solution of a nitrile rubber compound (above formulation example) is applied, dried at 80 ° C. for 6 minutes, and then heated at 200 ° C., 10 kgf / m ² (1 MPa) for 5 minutes. Pressure vulcanization was carried out to form a rubber layer having a thickness of 25 μm to obtain a nitrile rubber metal laminated gasket material.

Example 2
In Example 1, the base treatment agent was changed to the following and used.
γ-aminopropyltriethoxysilane-5 parts by weight vinyltriethoxysilane (weight ratio 3: 1) copolymer oligomer tetraisopropoxy titanium 20
Organosilica sol (Nissan Chemical Methanol Silica Sol) 16.7 〃 (5)
Methanol 2958 〃
The parenthesis indicates the solid content weight.

Example 3
In Example 1, the vulcanized adhesive was changed to the following and used.
Phenol resin adhesive (Rohm & Haas product Sixon 715-A) 12 parts by weight Hexamethylenetetramine curing agent (Company product 715-B) 0.4 部
Organosilica sol (Snowtex MEK-ST) 8 〃
Nitrile rubber compound (25% by weight toluene solution) 6 〃
Methyl ethyl ketone 173.6 〃

Example 4
In Example 1, the surface treatment agent was changed to that used in Example 2, and the vulcanized adhesive was changed to that used in Example 3, respectively.

Example 5
In Example 1, the vulcanized adhesive was used by changing to one that does not contain organosilica sol.

Reference Example In Example 1, a SUS301 steel plate that had been subjected to coating-type chromate treatment was used.

Comparative Example 1
In Example 1, the base treatment was not performed.

Comparative Example 2
In Example 1, the base treatment agent was used by changing it to one not added with organosilica sol.

Comparative Example 3
In Example 1, the base treatment agent was changed to the following (silane coupling agent: organic titanium = 1: 0.8) and used.
γ-aminopropyltriethoxysilane-15 parts by weight vinyltriethoxysilane (weight ratio 3: 1) copolymer oligomer tetraisopropoxytitanium 12 部
Organosilica sol (methanol silica sol) 16.7 〃
Methanol 3161 〃

The gasket materials obtained in the above examples and comparative examples were subjected to LLC resistance test and heat resistance test.
LLC resistance test: Rubber-metal laminated gasket material was immersed in a 50 wt% LLC (Nippon Chemical Industrial Products JCC310) aqueous solution at 150 ° C for 100 hours, followed by a Goban eye peel test (JIS K5600-5-6 coating adhesion) Heat resistance test: Rubber-metal laminated gasket material was exposed to air heating at 200 ° C for 70 hours, and then tested for bending resistance using a mandrel with a diameter of 4mm (JIS) K5600-5-1 compliant) and evaluated according to the following criteria: Score 1: No cracking or peeling 〃 2: Small cracks on the end face 〃 3: Small cracks overall 〃 4: Overall cracks Yes 〃 5: Completely peeled

The results obtained are shown in the following table.
table
Test item Example comparative example
1 2 3 4 5 Reference Example 1 2 3
LLC resistance test Initial 0 0 0 0 0 0 2 0 0
After 70 hours 0 0 0 0 1 0 3 4 0
140 〃 0 0 0 0 2 0 3 4 1
280 ０ 0 1 0 0 3 0 5 5 2
500 ０ 0 1 0 1 3 0 5 5 2
Heat resistance test 1 1 1 2 3 1 3 4 2

Since the rubber-metal laminated gasket material according to the present invention is excellent in LLC resistance and heat resistance, it is effectively used as a metal gasket to be mounted on an automobile engine or the like that is in contact with a long life coolant.

Claims (9)

  A rubber formed by sequentially laminating (a) a silane coupling agent, (b) an organometallic compound and (c) a silica-containing ground treatment agent layer, a phenol resin-containing vulcanized adhesive layer, and a rubber layer on a stainless steel plate. -Metal laminated gasket material.   The rubber-metal laminated gasket material according to claim 1, wherein the silane coupling agent is a copolymer oligomer of an amino group-containing alkoxysilane and a vinyl group-containing alkoxysilane.   2. The rubber-metal laminated gasket material according to claim 1, wherein the organometallic compound is an organotitanium, zirconium, tin or aluminum compound.   The rubber-metal laminated gasket material according to claim 1, wherein an organometallic compound having a weight ratio of 2 to 15 with respect to the silane coupling agent is used.   The rubber-metal laminated gasket material according to claim 1, wherein the silica is an organosilica sol.   The rubber-metal laminated gasket material according to claim 1 or 5, wherein silica is used in an amount of 5 to 50% by weight in the surface treatment agent.   The rubber-metal laminated gasket material according to claim 1, wherein the phenol resin-containing vulcanized adhesive is a vulcanized adhesive containing a novolak phenol resin, a resole phenol resin and silica.   The rubber-metal laminated gasket material according to claim 1, wherein the phenol resin-containing vulcanized adhesive is a rubber-containing vulcanized adhesive. The rubber-metal laminated gasket material according to any one of claims 1 to 8, which is used as a metal gasket for an engine.