As the base material for coating, unlike steel and wood, rubber is a high molecular compound with much lower surface energy, which is not conducive to the adhesion of coatings. And because the rubber itself is an elastomer, it requires that the elastic modulus of the paint film can be matched in a large range. At the same time, different rubber products have a certain solubility in solvent with different solubility parameters, which has a great influence on the selection of solvent system and the adhesion of the coatings. This is also one of the important differences with the iron and steel substrate.
In addition, the thermal deformation temperature of most of the rubber products is low, it is not suitable to use the way of heating and curing to finish the crosslinking curing of the coating, which puts forward higher requirements for the selection and coating process of the coating. It can be seen that the rubber coating must be adapted to a variety of base material and its surface properties, mechanical properties, thermal expansion properties and thermal deformation characteristics, as well as the corresponding protection, decoration and functional requirements, belongs to a large category of coatings with special requirements. There are many kinds of rubber products with different shapes and sizes. The coating method and surface treatment technology differ widely. The painting process has been developing very fast in recent years.
In the coating process of rubber products, the surface treatment occupies a special position, the surface of the rubber is relatively low, and it is easy to take electrostatic adsorption dust. It may also have forming processing auxiliaries and all kinds of additives, such as demoulding agent, which migrate to the surface. Considering the reduction of surface crystallinity, the possibility of producing defects in rubber products is even more complicated. The special physical and chemical properties of nitrile rubber surface make NBR products surface pretreatment before coating protection.
The surface treatment of NBR is usually treated by chemical treatment. This method is not affected by the complexity of the surface morphology of the material. It can evenly treat any part of the product exposed to the surface, usually toluene, butanone, acetone, cyclohexanone, dichloromethane and methanol, according to the surface properties of the material and the solvent evaporation rate. The above solvents are mixed in a certain proportion to form a mixed solvent. The organic solvent can remove the aging products and dust on the surface of the material and the various organic auxiliaries and monomers and low molecular products transferred by the material, and produce corrosion and swelling, increase the surface roughness of the material and improve the adhesion property of the NBR material itself.
The pretreatment method is used as the solvent cleaning in the chemical treatment, the selection of the cleaning agent before cleaning, the selection of the material as the commonly used detergent acetone, butanone and the low influence of the corrosive effect of the nitrile rubber, and by comparing the quality of acetone, butanone and fatty hydrocarbon solvent to the quality of the nitrile rubber ducts. The rate of washing and the rate of volume change were tested to select suitable cleaning agents for rubber conduits.