JP4784070B2 - Vulcanized adhesive rubber-stainless steel composite - Google Patents

Description

The present invention relates to a vulcanized adhesive rubber-stainless steel composite . More specifically, water resistance and heat resistance good vulcanizing adhesion rubber - about stainless steel composite.

Stainless steel is mainly used as the metal material for rubber-metal composites such as oil seals, gaskets, diaphragms and valves that require water resistance, LLC (long life coolant) resistance and heat resistance. , applying a direct vulcanization adhesive to the stainless steel, deteriorate the liquid-adhesion durability be adhered with rubber, when carrying out immersion tests with this rubber-metal laminate water, the LLC and the like, resulting in adhesion peel It becomes like this.

As a countermeasure for this, the present applicant has previously proposed that a coating chromate treatment is performed on stainless steel as a pretreatment for applying a vulcanized adhesive to improve resistance to water, LLC, and the like. However, the coating-type chromate treatment is not preferable from the viewpoint of environmental measures because it contains Cr ⁶⁺ ions.
JP 2000-006307 A Japanese Patent Laid-Open No. 11-221875

  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 applicant further formed a rubber-metal composite with excellent water-resistant adhesion without subjecting the metal to harmful coating-type chromate treatment when forming a composite of rubber and metal such as stainless steel. As a vulcanization adhesion primer that can be produced, a vulcanization adhesion primer containing a copolymer oligomer of an amino group-containing alkoxysilane and a vinyl group-containing alkoxysilane and an organometallic compound is provided. This primer for vulcanization adhesion satisfies the intended purpose, for example, JIS K6256 90 ° peel test method after 70-280 hours of immersion in warm water at 80 ° C, but still has more severe conditions. In order to be able to withstand the water resistance test, the improvement for that is required.
JP 2004-26848 A

An object of the present invention is to provide a vulcanized adhesive rubber-stainless steel composite using a chromium-free surface treatment agent for stainless steel containing a copolymer oligomer of an amino group-containing alkoxysilane and a vinyl group-containing alkoxysilane and an organometallic compound. For example, to provide a rubber having a good rubber remaining area ratio even after being immersed or exposed to 120 ° C. warm water or 175 ° C. for 70 to 280 hours, and also in the JIS K6256 90 ° peeling test method. is there.

The object of the present invention is achieved by a vulcanized adhesive rubber-stainless steel composite in which stainless steel surface-treated with a surface treatment agent obtained by adding zinc oxide to the chromium-free surface treatment agent for stainless steel is used. .

By adding further zinc oxide to a chromium-free surface treatment agent for stainless steel, a copolymer oligomer of an amino group-containing alkoxysilane and a vinyl group-containing alkoxysilane and an organometallic compound are added. even after 70 to 280 hours immersion or exposure to air, vulcanization rubber showing a JIS K6256 90 ° peel test method Oite good rubber remaining area ratio - stainless steel composite is provided.

Such a chromium-free surface treatment agent is applied to stainless steel, generally stainless steel sheet, and is used for vulcanized adhesive rubber-stainless steel composite parts for automobiles, industrial machines, etc. that require strict water-resistant adhesion, such as engine cylinder gaskets. It is used effectively during production.

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.
WO 02/24826

  Examples of vinyl group-containing alkoxysilanes that are other components include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, and the like. 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 include tetraisopropoxy titanium, tetra n-butoxy titanium, diisopropoxy titanium bis (ethylacetoacetate), 1,3-propanedioxytitanium bis (ethylacetoacetate), diisopropoxytitanium bis (acetylacetonate). ), Organic titanium compounds such as titanium tetraacetylacetonate, organic zirconium compounds such as tetra-n-propylzirconium, tetra-n-butoxyzirconium, di-n-butoxyzirconium bis (acetylacetonate), di-n-butoxyzirconium bis (ethyl Acetoacetate), diisopropoxyzirconium bis (acetylacetonate), dibutyltin dilaurate, dibutyltin dioctate, organotin compounds such as dioctyltin dilaurate, triisopropoxyaluminum, mono-s ec-butoxy dipropoxy aluminum, tri-sec-butoxy aluminum, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), monoisopropoxy aluminum bis (acetylacetonate), aluminum monoacetylacetonate bisethylacetoacetate And organoaluminum compounds such as 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.

  These organometallic compounds are used in an amount of about 30 to 900 parts by weight, preferably about 100 to 500 parts by weight based on 100 parts by weight of the total amount of the amino group-containing alkoxysilane and vinyl group-containing alkoxysilane used for forming the copolymer oligomer. Used in parts ratio. If it is used in a proportion higher than this, the compatibility with the top coat adhesive is deteriorated, leading to a decrease in adhesiveness. On the other hand, if it is used in a smaller proportion, the water resistance is lowered.

Zinc oxide is used in an amount of about 0.2 to 50 parts by weight, preferably about 0.5 to 20 parts by weight, based on 100 parts by weight of the organometallic compound. If the addition ratio is higher than this, the zinc oxide itself is not mixed well. On the other hand, if the addition ratio is lower than this, the desired desired water resistance and heat resistance cannot be obtained.

  The chromium-free surface treatment agent for stainless steel containing the above components as essential components is an organic solvent such as alcohols such as methanol, ethanol, isopropanol, etc., so that the total concentration of these components is about 0.2 to 3% by weight, It is prepared as an organic solvent solution of ketones such as acetone and methyl ethyl ketone, and water of about 20% by weight or less can be mixed and used as long as the solution is stable. Mixing water in an organic solvent serves to increase the reactivity of the copolymer oligomer.

  Vulcanization adhesion of rubber using such a chromium-free surface treatment agent for stainless steel is performed by applying this surface treatment agent organic solvent solution on stainless steel, drying, and then vulcanization adhesion for various rubbers. A method in which an agent is applied and dried under suitable drying conditions, and then an unvulcanized rubber compound or the like is joined, followed by pressure and heat vulcanization, or a rubber in which an unvulcanized rubber compound or the like is dissolved in a solvent It is performed by a method of coating a solution and heating and vulcanizing under pressure or without pressure.

As the stainless steel, SUS301, SUS301H, SUS304, SUS430 or the like is used, and in the case of a gasket application, a stainless steel plate having a thickness of about 0.1 to 2 mm is generally used. Application of the surface adhesive organic solvent solution onto these stainless steel plates can be performed by variously selecting various coating methods such as brush coating, dipping, spraying, and roll according to the purpose. Application is performed at a weight per unit area (film amount) of about 10 to 1000 mg / m ² , preferably about 50 to 500 mg / m ² .

  A vulcanized adhesive corresponding to the type of rubber to be bonded is applied on the surface treatment agent layer applied on the stainless steel plate and subjected to the drying treatment. As a vulcanized adhesive, when making a rubber-stainless steel composite with nitrile rubber or acrylic rubber, commercially available phenol resin adhesive (containing nitrile rubber) is generally used as the vulcanized adhesive. Commercially available products include Toyo Chemical Laboratory product Metalolc N31, Rohm and Haas product Sixon 715, Road Far East product Chemlock TS1677-13, and the like.

In the case of producing a vulcanized adhesive rubber-stainless steel composite with fluoro rubber, a resin adhesive containing an epoxy resin, a phenol resin and a tertiary amine compound is used. As the epoxy resin, for example, a phenol novolac type epoxy resin, an o-cresol novolak type epoxy resin, or the like is used. Further, as the phenol resin, a novolak type phenol resin obtained by condensation polymerization of phenol compounds such as phenol, cresol, alkylphenol and formaldehyde is generally used. For example, 2,4,6-tris (dimethylaminomethyl) phenol, 2-methylimidazole, 2-ethyl-4-methylimidazole and the like are used as the tertiary amine compound that acts as a curing agent for each of these components. As the vulcanized adhesive for fluoro rubber, commercially available products such as Sixon 300/311 (Rohm and Hans product) can be used as they are.

These vulcanized adhesives generally have a component concentration of about 0.1 to 10 weight by using an alcohol organic solvent such as methanol, ethanol or isopropanol or a ketone organic solvent such as acetone, methyl ethyl ketone or methyl isobutyl ketone alone or as a mixed solvent. % As a solution, applied by the same coating method as the surface treatment agent, with a single-surface weight (film amount) of 50 to 2000 mg / m ² , and dried under the drying and baking conditions suitable for the adhesive used. And baked.

  On the vulcanized adhesive layer thus formed, a method of bonding an unvulcanized nitrile rubber compound, a hydrogenated nitrile rubber compound, an acrylic rubber compound, a chloroprene rubber compound or a fluorine rubber compound, or an organic solvent thereof. It is applied as a solution.

Nitrile rubber for which NBR or hydrogenated NBR is used can be used as a compound using a sulfur vulcanizing agent such as sulfur or tetramethylthiuram monosulfide, but preferably an organic peroxide is used as a crosslinking agent. Used as an unvulcanized nitrile rubber compound. Examples of such peroxide-crosslinked unvulcanized nitrile rubber compounds include the following blending examples.
(Formulation example I)
NBR (medium-high nitrile; JSR product N237) 100 parts by weight
HAF carbon black 10 〃
SRF carbon black 40 〃
Powdered cellulose 10 〃
Zinc oxide 10 〃
Stearic acid 1 〃
Microcrystalline wax 2 〃
Anti-aging agent (ODA-NS, Ouchi Emerging Chemicals) 4 〃
Plasticizer (Buyer OT product from Bayer) 5 〃
Organic peroxide (NIPPON OIL & PRODUCTS PERHEXA 25B) 6 〃
N, Nm-Phenylenedimaleimide 1 〃
(Composition Example II)
NBR (Nippon ZEON product DN402; CN23%) 100 parts by weight
SRF carbon black 93
Plasticizer (DOP) 15 〃
Zinc oxide 3 〃
Stearic acid 1 〃
Anti-aging agent (Ouchi Emerging Chemical Product Nocrack 224) 1 〃
Anti-aging agent (Company product Noxeller M) 1 〃
Anti-aging agent (the company's product Noxeller TT) 3 〃
Anti-aging agent (Company product Noxeller PZ) 0.8 〃
Sulfur 0.5 〃

Moreover, the following are shown as a compounding example of acrylic rubber and chloroprene rubber.
(Formulation example III)
Active chlorine-containing acrylic rubber (Unimatec product PA402) 100 parts by weight
HAF carbon black 40 〃
Powdered silica 2 〃
Microcrystalline wax 6 〃
Stearic acid 3 〃
4,4'-bis (2,2'-dimethylbenzyl) diphenylamine 2
Sulfur 1 〃
Sodium stearate 3.5 〃

(Formulation example IV)
Chloroprene rubber (Denka product DCR-31) 100 parts by weight
HAF carbon black 50 〃
Zinc oxide 5 〃
Magnesium oxide (# 150) 4 〃
Anti-aging agent (Kawaguchi Chemical 3C) 3
Anti-aging agent (ODA-NS, Ouchi Emerging Chemicals) 3 〃
Paraffin wax 2 〃
Plasticizer (DIDA) 15 〃
Anti-aging agent (Ouchi Emerging Chemicals Noxeller TT) 2 〃
Vulcanization accelerator (Kawaguchi Chemical Accelerator 22) 2 〃

  As the fluororubber, both polyol vulcanizability and peroxide vulcanizability can be used. Examples of the unvulcanized fluororubber compound include the following blending examples.

  As the polyol vulcanizable fluoro rubber, generally vinylidene fluoride and other fluorine-containing olefins such as hexafluoropropene, pentafluoropropene, tetrafluoroethylene, trifluorochloroethylene, vinyl fluoride, perfluoro (methyl vinyl ether), etc. Examples of such a fluororubber include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4- Polyol is vulcanized with polyhydroxy aromatic compounds such as (hydroxyphenyl) perfluoropropane and hydroquinone.

  Examples of the peroxide vulcanizable fluororubber include fluororubbers having iodine and / or bromine in the molecule, and these fluororubbers are added by organic peroxides generally used for peroxide vulcanization. Sulfurized (crosslinked). In this case, it is preferable to use a polyfunctional unsaturated compound represented by triallyl isocyanurate together with the organic peroxide.

(Formulation example V)
Fluoro rubber (DuPont product Viton E45) 100 parts by weight Calcium metasilicate 40 部
MT carbon black 2 〃
Magnesium oxide (Kyowa Chemical Product Magnesia # 150) 6 〃
Calcium hydroxide 3 〃
Vulcanizing agent (DuPont product curative # 30) 2 〃
Vulcanization accelerator (the company's product curative # 20) 1〃
(Composition Example VI)
Fluoro rubber (DuPont Viton E60C) 100 parts by weight Vulcanizing agent (DuPont Diac No. 3) 3 〃
Magnesium oxide (Kyowa Chemical Product Magnesia # 30) 10 〃
MT carbon black 30 〃
(Formulation example VII)
Fluororubber (Daikin product Daiel G901) 100 parts by weight Calcium metasilicate 20 〃
MT carbon black 20 〃
Magnesium oxide (magnesia # 150) 6 〃
Calcium hydroxide 3 〃
Triallyl isocyanurate 1.8 〃
Organic peroxide (NIPPON OIL & PRODUCTS PERHEXA 25B) 0.8 〃

  The bonded unvulcanized rubber layer is vulcanized by pressurizing and heating it. 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, methyl ethyl ketone, methyl isobutyl ketone, etc. After volatilizing aromatic hydrocarbons such as ketones, toluene, xylene or a mixed solvent thereof, heat vulcanize at about 150 to 230 ° C for about 0.5 to 30 minutes, pressurize and vulcanize as necessary It is also done.

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

Example 1
Silane copolymer oligomer 1 part by weight Titanium tetra (acetylacetonate) 2.5 〃
Zinc oxide (ZnO) 0.5 〃
Methanol 86 〃
10 liters of water
The surface treatment agent was applied on a SUS304 steel plate so as to have a coating amount of 250 mg / m ² and dried at 200 ° C. for 1 minute.

  The silane copolymer oligomer used as the surface treating agent component was charged with 40 parts by weight of γ-aminopropyltriethoxysilane and 20 parts by weight of water in a three-necked flask equipped with a stirrer, a heating jacket and a dropping funnel. Adjust the pH by adding acetic acid until it becomes 4-5, and after stirring for several minutes, while continuing further stirring, slowly add 40 parts by weight of vinyltriethoxysilane using a dropping funnel. It was obtained by heating to reflux at 60 ° C. for 5 hours and cooling to room temperature.

  Next, a methyl ethyl ketone solution of a phenolic resin vulcanized adhesive (Rohm and Hans product Sixon 715) was applied as an adhesive for nitrile rubber or acrylic rubber on a SUS304 steel sheet coated with a surface treatment agent. Applied a methyl ethyl ketone solution of a phenol resin epoxy resin vulcanized adhesive (Metal Rock XN-870, manufactured by Toyo Chemical Laboratory), dried at room temperature, and then baked at 150 ° C. for 10 minutes.

  On this adhesive layer, an unvulcanized rubber compound of nitrile rubber compound (formulation example I), acrylic rubber compound (formulation example III) and fluororubber (formation example V) is placed, and 180 ° C. for 6 minutes. Pressure vulcanization was performed to obtain a JIS K-6256 90 ° peel test specimen made of three types of rubber.

Example 2
In Example 1, the same amount of di-n-butoxyzirconium bis (ethylacetoacetate) was used instead of titanium tetra (acetylacetonate).

Comparative Example 1
In Example 1, zinc oxide was not used, and the amount of methanol was changed to 86.5 parts by weight.

Comparative Example 2
In Example 1, titanium tetra (acetylacetonate) and zinc oxide were not used, and the amount of silane copolymer oligomer was changed to 2.5 parts by weight, and the amount of methanol was changed to 87.5 parts by weight.

Comparative Example 3
In Example 1, no silane copolymer oligomer was used, and the amount of methanol was changed to 87 parts by weight.

Comparative Example 4
In Example 1, the surface treatment with the surface treatment agent was not performed.

Comparative Example 5
In Example 1, a commercially available silane-based adhesive (Chemlock AP-133 manufactured by Road Far East) was used as the surface treatment agent.

Comparative Example 6
In Example 1, a commercially available zirconium-based surface treatment agent ( Nippon Parkerizing Product Palcoat 3762) was used as the surface treatment agent.

Measured when the 90 ° peel test specimens obtained in each of the above Examples and Comparative Examples were immersed in warm water at 120 ° C or left in heated air at 175 ° C for 70 hours, 140 hours and 280 hours. The remaining rubber area ratio (unit:%) is shown in the following table.
table
Example Comparative Example
Measurement conditions 1 2 1 2 3 4 5 6
[Nitrile rubber]
Initial 100 100 100 100 100 100 100 100
After immersion in warm water at 120 ° C for 70 hours 100 100 80 40 60 0 0 100
After immersion in warm water at 120 ° C for 140 hours 100 100 60 30 60 0 0 100
After immersion in warm water at 120 ° C for 280 hours 100 100 20 0 30 0 0 100
After heating at 175 ° C for 70 hours 100 100 100 100 50 0 100 0
After heating at 175 ° C for 140 hours 100 100 100 80 30 0 80 0
After air heating at 175 ° C for 280 hours 100 100 80 70 20 0 70 0
[Acrylic rubber]
Initial 100 100 100 100 100 100 100 100
After immersion in warm water at 120 ° C for 70 hours 100 100 90 40 50 0 40 100
After immersion in warm water at 120 ° C for 140 hours 100 100 60 20 30 0 20 100
After immersion in warm water at 120 ° C for 280 hours 100 100 40 10 20 0 10 100
After heating at 175 ° C for 70 hours 100 100 100 100 40 0 80 0
After heating at 175 ° C for 140 hours 100 100 80 70 30 0 50 0
After air heating at 175 ° C for 280 hours 100 100 50 70 20 0 20 0
[Fluoro rubber]
Initial 100 100 100 100 100 0 100 100
After immersion in warm water at 120 ° C for 70 hours 100 100 60 10 30 0 30 100
After immersion in warm water at 120 ° C for 140 hours 100 100 50 0 20 0 0 100
After immersion in warm water at 120 ° C for 280 hours 100 100 20 0 10 0 0 100
After heating at 175 ° C for 70 hours 100 100 100 100 60 0 100 0
After heating at 175 ° C for 140 hours 100 100 90 80 50 0 60 0
After air heating at 175 ° C for 280 hours 100 100 80 80 40 0 50 0

Claims (2)

Copolymerization oligomer, an organic metal compound and comprising zinc oxide stainless steel chrome-free surface treatment surface treated stainless steel vulcanizing adhesion used in agents of an amino-containing alkoxysilane with a vinyl group-containing alkoxysilane Rubber-stainless steel composite. The vulcanized adhesive rubber-stainless steel composite according to claim 1, wherein the stainless steel is a plate-like body.