JP4626223B2 - Vulcanized adhesive composition - Google Patents

Description

The present invention relates to a vulcanized adhesive composition. More specifically, the present invention relates to a vulcanized adhesive composition suitably used for vulcanization adhesion between a stainless steel plate and nitrile rubber or acrylic rubber .

As a gasket mounted on an automobile engine or the like, a rubber-coated stainless steel plate in which a rubber layer is laminated on a stainless steel plate is generally used. As such a rubber-coated stainless steel plate, a gasket material in which a chromium compound-silica-organic resin-based chromate film is formed on one or both surfaces of a stainless steel sheet and a rubber layer is laminated on the chromate film has been conventionally used. Such a gasket material having a rubber layer on a chromate-treated stainless steel plate has excellent heat resistance, water resistance, antifreeze liquid (LLC) resistance, and the like.
Japanese Unexamined Patent Publication No. 03-227622

However, in recent years, because as the growing interest in environmental protection, has become a strong movement to avoid the use of hazardous substances, Cr ⁺⁶ in particular, are included in the chromate treatment liquid on a direct adverse effect on the human body, Cr ⁺ There has been a demand for non-use of chromate treatment including ⁶ . Moreover, the chromium in the chromate film is highly likely to be extracted when it comes into contact with antifreeze or oil. Furthermore, the waste liquid containing Cr ⁺⁶ must be subjected to a special treatment stipulated by the Water Pollution Control Law, so there is a problem that the waste of stainless steel material subjected to the chromate treatment cannot be recycled.

On the other hand, in the case of a gasket that is not subjected to conventional chromate treatment, the actual performance has not yet been obtained as in the case of a gasket that has been subjected to chromate treatment. Currently, various gaskets using alternative chromate treatment have been proposed, but if this is used for water applications such as automobile engines, blisters will occur at the wetted part adhesion interface during long-term use. It has the disadvantage of being easy.
JP 2003-105321 A

  Under these circumstances, there is a need for a gasket that has heat resistance or adhesiveness equivalent to or higher than that of a chromate-treated gasket, and also has durability against water and antifreeze, and is environmentally friendly. Yes.

An object of the present invention is to provide a vulcanized adhesive composition capable of effectively vulcanizing and bonding nitrile rubber or acrylic rubber without performing chromate treatment of the stainless steel plate when vulcanizing and bonding nitrile rubber or acrylic rubber to a stainless steel plate. To provide things.

The object of the present invention is that the blending ratio in the solid content of the adhesive is (a) 40 to 80% by weight of the phenol resin, (b) 5 to 40% by weight of the solvent-dispersible silica and / or hydrotalcite-related compound and the balance. (c) it is achieved by a nitrile rubber compound and / or fluorine vulcanizable adhesive composition comprising rubber.

The vulcanized adhesive composition according to the present invention has a water resistance test under conditions of 95 ° C. and 7 days, a LLC resistance test under conditions of 120 ° C. and 14 days, and a chromate treatment that adversely affects the human body. In a heat resistance test at 200 ° C for 3 days, it shows the same satisfactory results as a chromate-treated stainless steel plate, so it can effectively join the stainless steel plate and nitrile rubber or acrylic rubber. .

  As the phenol resin of component (a) used for vulcanization adhesion of nitrile rubber or acrylic rubber, resol type phenol resin, novolac type phenol resin or a mixture of these phenol resins is used, preferably resol type phenol resin and novolac type A mixture of phenolic resins is used. These phenol resin components are used so that the solid content (or resin content) in the adhesive is 100 to 50 to 90% by weight, preferably 65 to 85% by weight. Further, when a rubber (compound) solution is used as the component (c), the component (a) is a solid content blending such that the solid content of the adhesive is 40 to 80% by weight, preferably 50 to 70% by weight. Used in proportions. If the amount of component (a) is less than this, it is not preferable because the adhesive strength is reduced. In fact, commercially available products such as Gunei Chemical Product RESIDTOP PSF2803 are used as novolak type phenol resins, and Sumitomo Bakelite product Sumilite PR-50232 is used as resol type phenol resins.

  As the solvent-dispersible silica as component (b), those corresponding to the dispersion medium of the vulcanized adhesive may be used, and an organosilica sol is preferably used from the viewpoint of dispersion stability in the adhesive. The primary particle diameter is 40 nm or less, preferably 5 to 30 nm, more preferably 10 to 20 nm. If a larger primary particle size is used, the effect will be reduced even if the same part by weight is blended, and if the number of parts added is increased to increase the effect, the adhesive will become brittle and its function will be reduced, eventually desired. The purpose cannot be achieved. Actually, Nissan Chemical Industries products methanol silica sol, Snowtex IPA-ST (isopropyl alcohol dispersion), Snowtex EG-ST (ethylene glycol dispersion), Snowtex MEK-ST (methyl ethyl ketone dispersion), which are commercially available products, Snowtex MIBK-ST (methyl isobutyl ketone dispersion) or the like is used.

The hydrotalcite-related compounds of component (b) include Mg _4.3 Al ₂ (OH) _12.6 CO ₃ · mH ₂ O, Mg ₆ Al ₂ (OH) ₁₆ CO ₃ · 4H ₂ O, Mg _4.5 Al ₂ ( OH) ₁₃ CO ₃ .3.5H ₂ O or the like is used. In practice, Kyowa Chemical Industry products DHT-4A, the company's products DHT-6, etc. are used.

  The component (b) is such that the blending ratio of the solvent-dispersible silica or the hydrotalcite-related compound in the adhesive solid content (or resin content) is 10 to 50% by weight, preferably 15 to 35% by weight. Added. When both of these are used in combination, the total amount (10 to 50 parts by weight) of these is used at such a ratio that the solid content concentration is obtained. Further, when a rubber (compound) solution is used as the component (c), the component (b) is contained in an amount of 5 to 40% by weight, preferably 10 to 30% by weight in the adhesive solid content. Used. (b) If the amount of component is less than this, water resistance and LLC resistance will not be sufficiently obtained, while if used in a proportion higher than this, the adhesive component will decrease due to the relative decrease of the adhesive component. Become.

In addition to the above essential components, component (c) nitrile rubber compound solution and / or fluororubber solution is appropriately blended as an additive in the adhesive . The blending amount is within the range of the remainder of the predetermined solid content concentration of the components (a) and (b), that is, the solid content blending ratio in the adhesive solid content is 55% by weight or less, preferably 10 to 30% by weight. It can mix | blend in the ratio. Here, the addition of a nitrile rubber compound solution can improve the adhesion, and the addition of a fluororubber solution can improve the adhesion and heat resistance. Nitrile rubber compound solutions include nitrile rubber, carbon black, reinforcing agents such as silica (in this case, silica is not calculated as compounding amount), zinc oxide, acid acceptors such as hydrotalcite (not calculated), stearic acid Lubricants such as dioctyl phthalate, anti-aging agents, sulfur or sulfur donating compound vulcanizing agents, tetramethylthiuram disulfide, vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide And the like are used as an organic solvent solution such as toluene and methyl ethyl ketone. As the fluororubber solution, an organic solvent solution of fluororubber such as toluene or methyl ethyl ketone is used.

  The vulcanized adhesive composition, after blending the above components, is about 0.5 to 10% by weight, preferably about 1%, of an alcohol-based organic solvent such as methanol, ethanol, isopropanol, or a ketone-based organic solvent such as acetone or methyl ethyl ketone. It is prepared as a dispersion having a concentration of ˜4% by weight, more preferably 2-3% by weight, which is applied by any means such as a brush coating method, a dipping method, a spray method, a spray method, a roll coater method, After drying with warm air, it is baked at about 100 to 250 ° C. for about 1 to 20 minutes, and has a thickness of about 0.1 to 15 μm, preferably about 0.5 to 6 μm, more preferably about 1 to 6 μm on the metal plate. An adhesive layer is formed.

As the metal plate on which the adhesive layer is formed, stainless steel, mild steel, brass, aluminum, aluminum die casting, etc. are used, preferably stainless steel plates such as SUS304, 430, 301, 301H, etc., which are coated with adhesive. After performing surface cleaning treatments such as degreasing and alkali washing before, alternative sub-treatment methods other than chromate treatment, for example, bisphenol having acidic content and moisture acidic silica, titanium compound and water-soluble nitrogen-containing substituent on the steel plate A Method for forming a film composed of a novolak polymer, a method for forming a primer layer of a silica-alumina condensate on a stainless steel plate, a method for forming an organic-inorganic composite film containing a titanium compound and fluoride on a stainless steel plate, etc. It is used after being subjected to primer treatment such as silane coupling agent.
JP 2003-105321 A Japanese Patent Laid-Open No. 2003-028307 JP 2002-264253 A

On the adhesive layer, an unvulcanized nitrile rubber compound or an acrylic rubber compound is made of metal by coating a rubber solution in which an unvulcanized rubber compound is dispersed in a solvent or by bonding an unvulcanized rubber compound. One or both sides joined together to form a rubber layer with a thickness of about 5 to 120 μm, heat vulcanize at about 150 to 230 ° C for about 0.5 to 30 minutes, and pressurize as necessary. The rubber is bonded by vulcanization. As a nitrile rubber compound or an acrylic rubber compound, when used as a gasket material, a vulcanized layer having a hardness (durometer A) of 80 or more and a compression set (100 ° C., 22 hours) of 50% or less is formed. It may be anything, and is not particularly limited depending on the content of the blend. In addition, about the product with high surface adhesiveness, apply | coating an anti-adhesive agent to the rubber layer surface of a rubber laminated metal plate is also performed.

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

Example 1
After degreasing the surface of SUS301H steel plate (thickness 0.2mm) with alkali degreasing, it contains H ₂ TiF ₆ 60g, H ₂ ZrF ₆ 10g, colloidal silica 6.4g, aminomethyl-substituted polyvinylphenol 50g and propoxypropanol 50g, deionized water A 1 liter aqueous solution was applied at a coating amount of 0.2 g / m ² at room temperature and dried at 100 ° C. for 1 minute. On this surface-treated stainless steel plate,
Phenolic resin solution (solid content concentration 35.9% by weight) 100 parts by weight (solid content 58.3% by weight)
Organosilica sol (Nissan Chemical Industries product MEK-ST 114 〃 (solid content 18.5% by weight)
; Solid content concentration 10% by weight, primary particle size 10-20 μm)
Nitrile rubber compound solution (solid content 25% by weight) 57 〃 (solid content remaining)
Methyl ethyl ketone 2800 〃
A vulcanized adhesive composition (total solid content concentration: 2% by weight) was applied, dried at room temperature, and baked at 190 ° C. for 5 minutes to form an adhesive layer.

In addition, the following were used as a phenol resin solution and a nitrile rubber compound solution.
[Phenolic resin solution] Solid content 35.9% by weight
Novolac type phenolic resin (Resitop PSF2803) 50 parts by weight Resole type phenolic resin 49% by weight solution (Sumilite PR-50232) 59 部
Hexamethylenetetramine 8 〃
Methyl ethyl ketone 125 〃
[Nitrile rubber compound solution]
Nitrile rubber (JSR product N235) 100 parts by weight
SRF carbon black 80 〃
Calcium carbonate 80 〃
Silica 20 〃
Zinc flower 5 〃
Anti-aging agent (Ouchi Emerging Chemical Product Nocrack 224) 2 〃
Triallyl isocyanurate 2 〃
1,3-bis (tert-butylperoxy) isopropylbenzene 2.5 〃
Plasticizer (Buyer OT product from Bayer) 5 〃
100 parts by weight of the kneaded product of the above components was dissolved in 300 parts by weight of a toluene-methylethylketone weight ratio (9: 1) mixed solvent to obtain a nitrile rubber compound solution having a solid concentration of 25% by weight.

On the adhesive layer-formed steel sheet, the nitrile rubber compound solution was applied and dried at 60 ° C. for 15 minutes to form an unvulcanized nitrile rubber layer with a thickness of one side of 20 μm on both surfaces of the steel sheet, 180 ° C., 5.88 MPa. Pressure vulcanization was performed under the conditions of (60 kgf / cm ² ) for 10 minutes to prepare a stainless steel-nitrile rubber composite (nitrile rubber laminated steel plate).

The following evaluation method was implemented about the produced nitrile rubber laminated steel plate.
Water resistance test: As an immersion test that takes into account the potential difference between dissimilar metals, a rubber metal laminate and an aluminum plate are inverted V-shaped for 7 days each in a 0.1% sodium bicarbonate aqueous solution at 95 ° C in a glass container. So that the top is in contact with the clip, so that the top is positioned above the liquid level, and the rubber metal laminate at the contact part scrapes the rubber part and the stainless steel plate part is the aluminum plate. after There performing the immersion test was in direct contact, cross-cut peel test (JIS K5600-5-6 of the coating film adhesion test method = cross-cut method = compliant) implementation
LLC resistance test: Soft metal is immersed in a 50% by weight long-life coolant solution at 120 ° C for 14 days after being immersed in a 50% by weight long-life coolant solution. Then, a gobang eye peel test is performed. Heat resistance test: Soft metal in an oven at 200 ° C for 3 days After exposure, gobang eye peel test

Example 2
In Example 1, a vulcanized adhesive composition was used in which the amount of organosilica sol was changed to 65 parts by weight (solid content 11.5% by weight) and the amount of methyl ethyl ketone was changed to 2610 parts by weight. In addition, 100 parts by weight of the phenol resin solution has a solid content of 63.4% by weight.

Example 3
In Example 1, as the vulcanized adhesive composition, 71 parts by weight of the fluororubber solution was used instead of the nitrile rubber compound solution, and the amount of methyl ethyl ketone was changed to 2790 parts by weight. As the fluororubber solution, a 20 wt% methyl ethyl ketone solution of fluororubber (DuPont product Viton A) was used.

Example 4
In Example 1, as the vulcanized adhesive composition, the amount of the nitrile rubber compound solution was changed to 28 parts by weight (solid content 11.4% by weight), and 36 parts by weight of the fluororubber solution (solid content 11.7% by weight) was added. What was done was used.

Example 5
In Example 1, 11.5 parts by weight (solid content 18.7% by weight) of hydrotalcite powder (Kyowa Chemical Industry Product DHT-6) was used in place of the organosilica sol as the vulcanized adhesive composition, and the amount of methyl ethyl ketone was 2910. What was changed into the weight part was used.

Example 6
In Example 1, as the vulcanized adhesive composition, the organosilica sol amount was changed to 85 parts by weight (solid content 12.7% by weight) and the methyl ethyl ketone amount was changed to 3110 parts by weight, respectively. Hydrotalcite powder (DHT -6) What added 8.5 weight part (solid content 12.7 weight%) further was used. Note that 100 parts by weight of the phenol resin solution has a solid content of 53.5% by weight.

Comparative Example 1
In Example 1, as the vulcanized adhesive composition, an organosilica sol was not used and the amount of methyl ethyl ketone was changed to 2350 parts by weight.

Comparative Example 2
In Example 1, a vulcanized adhesive composition was used in which the amount of organosilica sol was changed to 400 parts by weight (solid content 44.4% by weight) and the amount of methyl ethyl ketone was changed to 3950 parts by weight. Note that 100 parts by weight of the phenol resin solution has a solid content of 39.8% by weight.

Comparative Example 3
In Example 1, 30 parts by weight of hydrotalcite (DHT-6) (solid content 32.8% by weight) was further used as the vulcanized adhesive composition, and the amount of methyl ethyl ketone was changed to 4280 parts by weight. It was. The solid contents of 100 parts by weight of the phenol resin solution and 114 parts by weight of the organosilica sol are 39.2% by weight and 12.5% by weight, respectively.

Reference example 1
In Comparative Example 1, a steel plate subjected to chromate treatment as a base treatment was used as the SUS steel plate.

The results of Examples 1 to 6, Comparative Examples 1 to 3, and Reference Example 1 are shown in the following table. All vulcanized adhesive compositions had a total solid content of 2% by weight.
table
Test item 1 actual 2 actual 3 actual 4 actual 5 actual 6 ratio 1 ratio 2 ratio 3 Reference example 1
Water resistance test 1 0 0 0 0 0 4 2 3 0
LLC test 1 0 0 0 1 0 5 4 3 0
Heat test 3 3 1 0 4 2 5 5 5 0

The vulcanized adhesive composition according to the present invention can effectively join a stainless steel plate and a nitrile rubber or an acrylic rubber when applied to a stainless steel plate not subjected to chromate treatment. Rubber-laminated steel sheets that are vulcanized and bonded using materials exhibit excellent water resistance and antifreeze resistance, so they are not only extremely effective as measures against social problems such as environmental conservation and recyclability, It also has a practical effect that it can be effectively used as a gasket to be mounted on an automobile engine or the like that requires such water resistance and antifreeze resistance.

Claims (4)

The blending ratio in the solid content of the adhesive is (a) 40 to 80% by weight of phenol resin, (b) 5 to 40% by weight of solvent-dispersible silica and / or hydrotalcite-related compound, and the balance is (c) nitrile rubber compound and A vulcanized adhesive composition used for vulcanization adhesion between a stainless steel plate and nitrile rubber or acrylic rubber, which is made of fluororubber . The adhesive composition according to claim 1, wherein the primary particle size of the solvent-dispersible silica is 5 to 30 nm. A nitrile rubber or acrylic rubber laminated stainless steel sheet vulcanized and bonded by the vulcanized adhesive composition according to claim 1. A gasket comprising the rubber-laminated stainless steel plate according to claim 3.