Bonding process of silicone rubber and metal

With the continuous innovation and progress of the technology in the silicone industry, the application of silicone rubber in life has become more and more extensive, but sometimes there are some problems in the application, such as how to bond silicone rubber products with metal. Next, Ribo will share with you the four-step process of realizing the bonding of silicone rubber and metal:

1、 In order to achieve adhesion in metal surface treatment, the metal surface must be treated first. The commonly used methods are: chemical, mechanical and solvent. Generally, the silicone rubber product factory selects the method according to the actual situation. The mechanical method usually uses sand blasting, abrasive cloth or grinding wheel grinding and other methods, especially the sand blasting method, which has low cost, high speed and good effect, and is widely used. Chemical methods are also commonly used, especially for anodizing of aluminum and its alloys and copper plating of steel. The treated metal surface shall be coated with adhesive, silicon rubber or immersed in inert solvent in time.

2、 The design of metal joint (recommended product: fluororubber joint) should realize the bonding of silicone rubber and metal. Next, we should start with the bonded joint. As part of the overall design of the product, we should first understand the design principle of the joint:

1) Increase the bonding area as much as possible to improve the bearing capacity of the bonding joint;

2) The stress mode of adhesive joint shall be shear force or tensile force to prevent peeling force;

3) The bonding length in the stress direction should not be too long, and the bonding width should be increased as much as possible;

4) The stress direction of lamination bonding shall avoid interlayer separation;

5) Oblique angle bonding is better than right angle bonding;

6) Transverse stressed joints shall be bonded with formwork. According to the above principles and the characteristics of rubber products, methods such as drilling holes in metal parts and turning thread grooves are generally adopted to improve the bonding strength of joints.

3、 Construction of adhesive

For metal parts with qualified surface treatment, the bonding surface can be painted by brushing, spraying, roller coating, knife scraping, dipping and other methods. The method used can be determined according to the size of the part and the characteristics of the adhesive.

4、 There are two methods for gluing and vulcanizing: hot pasting and cold pasting. After gluing, it can be compacted mechanically or by pressing. The film should not be too thick. The thin film should be pasted layer by layer to the required thickness. Generally, the thickness of hard film is 0.1 to 1.5 mm, and the thickness of soft film is not more than 4 to 5 mm to avoid bubbles in the film. Vulcanization bonding can be divided into hot vulcanization and cold vulcanization. Thermal vulcanization bonding is to complete the bonding between rubber and metal under certain pressure and temperature. Cold vulcanization bonding is to use the adhesive at room temperature and allow it to be naturally vulcanized by pressing for a certain time to make the vulcanizate bond with the metal. Pressure is an indispensable condition for the bonding process. The pressure and temperature depend on the product and its formula.

To sum up, to realize the bonding of silicone rubber and metal, it is necessary to follow four steps: metal surface, joint, adhesive, and bonding method. However, the silicone product factory should pay attention to the following points when realizing the bonding. For example, if the metal surface treated by chemical method is not treated in time, it will be polluted by dust, temperature, and other kinds of oxidation and rust. In addition, the construction of adhesive should be uniform and have a certain amount of adhesive, The ambient temperature during sizing should be controlled at 15~35 ℃, and the relative humidity should be below 70% to make the solvent volatilize completely and avoid dew on the surface.