JP4566535B2 - Gasket material - Google Patents

Description

  The present invention relates to a gasket material to be mounted on a vehicle engine, and more particularly to a gasket material with improved durability against antifreeze.

  A rubber coated stainless steel plate in which a rubber layer is laminated on a stainless steel plate is generally used for a gasket mounted on a vehicle engine, particularly for a head gasket. In addition, in order to hold the rubber layer more firmly, a gasket material in which a chromate film consisting of a chromium compound, phosphoric acid, and silica is formed on one or both surfaces of a stainless steel plate and the rubber layer is laminated on the chromate film is also widely used. (For example, refer to Patent Document 1).

  In addition, damage to the head gasket material during engine operation includes (1) adhesion failure between the rubber and steel plate due to penetration of cooling water and oil into the rubber layer, and (2) adhesion failure between the rubber and steel plate due to combustion heat. It is considered. In order to prevent such adhesion failure, a chromate-treated film is generally interposed between the steel plate and the rubber layer. The high adhesion of the material for chromate treatment head gasket is due to the strongness between the steel plate / chromate treatment film and the chromate treatment film / rubber layer, and is estimated as follows. When the chromate treatment solution is applied to the steel sheet, the dichromic acid etches the steel sheet surface and a polar component is introduced into the steel sheet surface, and this polar component and the chromate film form a secondary bond. This is thought to be due to the strong adhesion. Further, the adhesion between the chromate-treated film / rubber layer is considered to be because the heated and dried dichromic acid and the polar group of the silica component adhere firmly to the polar group of the rubber layer. Moreover, in order to maintain these adhesions in each environment, the coating itself needs to be stable against the permeation liquid and heat.

JP-A-3-227622 (Claims, pages 3 to 4)

  The gasket material provided with the rubber layer on the chromate-treated stainless steel plate is excellent in heat resistance, adhesion with antifreeze liquid, and the like. Chromate treatment tends to be avoided because of the drawback that chromium has a direct adverse effect on the human body. Further, the waste liquid containing hexavalent chromium needs to be subjected to a special treatment specified in the Water Pollution Control Law, and there is a disadvantage that the waste of stainless material subjected to the chromate treatment cannot be recycled. Furthermore, there is a high possibility that chromium in the chromate film is extracted by contact with antifreeze or oil.

  As described above, the gasket material subjected to the chromate treatment has a great environmental problem. Accordingly, it is an object of the present invention to provide a gasket material having heat resistance and adhesiveness equal to or higher than those of a gasket material subjected to chromate treatment, particularly having adhesion durability against antifreeze liquid, and having no environmental problems. And

  The present invention was made paying attention to such conventional problems, and as a result of earnestly examining a film not containing chromium in order to obtain physical properties equivalent to or higher than those of a chromate-treated product, It has been found that the above object can be achieved by forming a reaction product or a reaction product of an acid component and a metal compound and a film made of silica on a steel sheet.

That is, the gasket material of the present invention is a gasket material to be mounted on a vehicle engine, and is a reaction product of at least a fluoro complex-containing acid component and a metal other than chromium on one or both surfaces of a steel plate, or at least A rubber layer is formed through a reaction product of an acid component containing a fluoro complex and a metal compound other than a chromium compound and a film made of silica.

  The gasket material of the present invention is extremely effective as a measure against social problems such as environmental protection and recyclability because it provides excellent adhesion and heat resistance to antifreeze without subjecting it to chromate treatment harmful to the human body. In addition, the practical effect is great.

The present invention will be described below. In the present invention, a reaction product between an acid component containing at least a fluoro complex and a metal other than chromium or a reaction product between an acid component containing at least a fluoro complex and a metal compound other than a chromium compound between the steel plate and the rubber layer. And a film made of silica is interposed.

Acid component used in the present invention is containing a fluoro complex, is a mixed acid, phosphoric acid, orthophosphoric acid, condensed phosphoric acid, phosphoric anhydride, acetic acid, formic acid, sulfuric acid, nitric acid, fluoride hydrochloric acid, and the like organic acids. These acid components are preferably blended in a proportion of 5 to 50% by weight in the solid content of the treatment liquid for film formation. More preferably, it is 10 to 30% by weight.

Off Ruoro complex is suitable for increasing the reaction efficiency stably. Examples of fluoro complexes include fluorotitanic acid, fluorozirconic acid, fluorosiliconic acid, fluoroaluminic acid, fluorophosphoric acid, fluorocobalt acid, fluorosulfuric acid, fluoroboric acid and the like. Also, full Ruorochitan acid or fluoro zirconate are good. When these acids are added, the reaction product of the acid component and the metal or the reaction product of the acid component and the metal compound is generated more quickly.

  As the silica used in the present invention, those excellent in dispersibility in the film-forming treatment liquid are preferable, and examples of such silica include colloidal silica and vapor phase silica. Although it does not specifically limit as colloidal silica, Snowtex C, Snowtex O, Snowtex N, Snowtex S, Snowtex UP, Snowtex PS-M, Snowtex PS-L, Snowtex 20, Snow Tex 30, Snowtex 40 (all manufactured by Nissan Chemical Industries, Ltd.), etc. can be obtained from the market. The gas phase silica is not particularly limited, but includes Aerosil 50, Aerosil 130, Aerosil 200, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil MOX80, Aerosil MOX170 (all manufactured by Nippon Aerosil Co., Ltd.), and the like. It can be obtained from the market. These silicas are preferably blended in the formed film in a proportion of 10 to 60% by weight. More preferably, it is 30 to 50% by weight.

  As the metal used in the present invention, Fe (iron), Zn (zinc), Ni (nickel), Al (aluminum), Ti (titanium), Zr (zirconium), Mg (magnesium), Mn (manganese), Examples include Ca (calcium), W (tungsten), Ce (cerium), V (vanadium), Mo (molybdenum), Li (lithium), and Co (cobalt). Examples of the metal compound include oxides, hydroxides, and fluorides of these metals. In particular, Fe, Zn, Al, Ti, Zr, oxides of these metals, hydroxides of these metals, and fluorides of these metals are preferable because of their high reactivity with the acid component and the rapid generation of reaction products. . These metals or metal compounds may be used alone or in combination, and the blending amount thereof is preferably 1 to 30% by weight in the solid content in the treatment liquid for film formation. More preferably, it is 5 to 20% by weight. In the case of a metal compound, the value is converted to the amount of metal element.

In order to form a film on a steel sheet, a predetermined amount of the above-mentioned silica, acid component, metal or metal compound is weighed, and a treatment liquid dispersed or dissolved in an appropriate solvent, for example, water, is applied to a roll coater or the like. What is necessary is just to apply | coat to one or both surfaces of a steel plate using a well-known application | coating means, and to dry a coating film at the temperature of about 150-250 degreeC. During this heat drying, the acid component reacts with the metal or metal compound to produce a metal compound, which forms a film together with silica. The coating amount is not limited, but about 50 to 500 mg / m ² is suitable for practical use.

  In the present invention, the steel plate is not particularly limited, and stainless steel (ferrite / martensite / austenite stainless), iron, aluminum, or the like can be used.

  And a rubber layer is formed on said membrane | film | coat, and the raw material for gaskets of this invention is completed. The rubber forming the rubber layer may be a known one, but NBR, fluorine rubber, silicon rubber, acrylobutadiene rubber, HNBR, EPDM, etc., which are excellent in heat resistance and chemical resistance, are suitable. For forming the rubber layer, a rubber liquid or latex obtained by dissolving a rubber material in an appropriate solvent is applied to a thickness of 20 to 130 μm with a skimmer coater or a roll coater, and the coating film is applied at 150 to 250 ° C. What is necessary is just to vulcanize-bond.

  Moreover, you may interpose a primer layer (for example, the adhesive agent of a nitrile rubber compound and a phenol resin) between a rubber layer and a membrane | film | coat as needed.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, these examples are described for the purpose of explaining the present invention and are not intended to limit the present invention.

(Sample preparation)
A coating solution for coating formation mixed with the composition shown in Table 1 by a roll coater was applied to both surfaces of the stainless steel plate, and the coating was dried at 180 ° C. to form a coating. The coating amount is shown in Table 2. Next, an adhesive composed of a nitrile rubber compound and a phenol resin was applied on the film and heat-treated to form a primer layer on the film. Moreover, the sample which does not form this primer layer was also produced ( reference example 5). Then, a solution obtained by dissolving nitrile rubber with a solvent was applied onto it (primer layer or coating) with a roll coater, and vulcanized and bonded at 180 ° C. for 10 minutes to form a rubber layer, which was used as a sample.

(Evaluation methods)
1. Durability against antifreeze The sample prepared above is immersed (half-immersed) to half the position so that it is perpendicular to the surface of the coolant for automobile radiators (Toyota genuine long life coolant). For 500 hours. And the sample was taken out from coolant liquid and the drawing test was done about the non-immersion part and the immersion part. A cross-cut tape peeling test was also performed. Each test method and evaluation criteria are as follows.

1-1. Drawing Test Using a drawing tester defined in JIS-K6894, a spiral with a radius of 4.5 mm was drawn 25 times on the sample surface and evaluated according to the following criteria. The results are shown in the respective columns of “Semi-immersed non-immersed part” and “Semi-immersed part” in “Durability against antifreeze” in Table 2.
・ Evaluation criteria 5 points: The rubber layer remains completely.
4 points: The rubber layer has partially dropped 3 points: About half of the rubber layer has fallen 2 points: The rubber layer has remained slightly 1 point: The rubber layer has completely dropped

1-2. Cross-cut tape peeling test This was performed in accordance with JIS-K5400 according to the following procedure.
(1) Make a grid-like cut with a clearance of 2 mm on the sample surface so that 100 grids can be formed.
(2) Affix the adhesive tape on the grid and rub it with an eraser to attach the adhesive tape completely.
(3) One or two minutes after the tape is attached, hold one end of the adhesive tape and momentarily peel it off in the direction perpendicular to the sample surface.
(4) The surface of the sample after peeling is observed, and the number of remaining grids is counted.
The results are shown in the column of “Total immersion” in “Durability against antifreeze” in Table 2.

2. Heat-resistant adhesion The prepared sample was left to heat at 200 ° C. for 500 hours, and then a cross-cut tape peeling test similar to the above was performed. The results are shown in the column of “Heat resistance” in Table 2.

As shown in Table 2, satisfying the present invention, a metal compound formed by reaction of the acid component and metal or acid component and a metal compound, Example 1 provided the coating film with the silica, the click chromate treatment Good evaluation results equivalent to those of Comparative Example 4 were obtained. However, Comparative Examples 1 to 3 provided with a film that does not satisfy the present invention are remarkably inferior in performance.

Claims (3)

A gasket material to be mounted on an engine of a vehicle, on one or both sides of the steel sheet, other than the acid component and chromium compound comprising the reaction product or at least fluoro complexes with metals other than the acid component and chromium containing at least fluoro complex A gasket material, characterized in that a rubber layer is formed through a film made of a reaction product with a metal compound and silica. An acid component is fluoro complexes, phosphoric acid, orthophosphoric acid, condensed phosphoric acid, phosphoric anhydride, acetic, formic, be a mixture of sulfuric acid, nitric acid, and at least one of hydrofluoric acid, selected from organic acid The gasket material according to claim 1. Metal is Fe (iron), Zn (zinc), Ni (nickel), Al (aluminum), Ti (titanium), Zr (zirconium), Mg (magnesium), Mn (manganese), Ca (calcium), W (tungsten) ), Ce (cerium), V (vanadium), Mo (molybdenum), Li (lithium), Co (claim 1 or 2 gasket material, wherein the at least one selected from cobalt).