Preparation Of One-component Polyurethane Coatings For The Surface Of The Silicone Rubber With High-protective

With the rapid development of computers, mobile phones and other electronic products in the world, key products have been a large-scale industry. Silicone rubber are widely used in mobile phones, copiers, home appliances, remote control, etc. keys, because of its excellent heat resistance, low temperature resistance, ozone resistance, weather resistance, electrical properties and high permeability elastomers.Because of the high frequency of use of keys, easy wear, which require high wear-resistant and good decorative coatings protection. But the Silicone rubber surface energy is low, poor adhesion of the coating, easy to fall off. At present, the high cost of UV-curable coatings, silicone coatings, due to the long production cycle, poor mechanical properties and solvent resistance, has been difficult to meet the rapidly expanding market demand. In the higher than its unblocking temperature conditions, Blocked polyurethane can get the high reactivity of NCO groups to react with the funetional groups of the treated surface.This article rubber, so that the coating has good adhesion and solvent resistance. This article rely on the business needs to the proposed a synthesis of a silicone rubber surface weathering, corrosion resistance and good decorative properties of coatings.In this paper, the preparation of molecular design of Polyester diols by1,4-Cyclohexanedimethanol and adipicacid as the raw material with excellent weathering resistance and solvent resistance, The influence of Alkyd ratio, reaction temperature, reaction time, amount of catalyst and reaction process of the polycarbonate diol preparation were studied. The results show that the best reaction conditions is setting the alkyd ratio of1.4:1, the amount of catalyst to1wt%, the first pre-polycondensation reaction at140℃2h, and then within one hour, heated to180℃C insulation response8h, the synthesis of Polyester diols with molecular weight of1500-1700, hydroxyl value of60-70mg KOH/g, and meet the desired design purposesPolyols resin and polycarbonate diol were mixed with an excess of IPDI to synthesis of end groups as the isocyanate groups of pre-polymer by the method of Semi-prepolymer. The influence of Types of polyols,-OH/-NCO (R value) molar ratio, reaction temperature and reaction time werer studied. The results show that1652,5651, c1200and homemade polycarbonate diol mixture as a polyol resin, R=2.5,80℃for2h preparation of the pre-polymer to meet response requirements. The products is characterized by Fourier transform infrared spectroscopy (FT-IR), Differential Scanning Caborimetry (DSC) and Nuclear Magnetic Resonance(NMR).and then the pre-polymer were blocked by diethylmalonate and other block agent to get the polyurethane solution. The influence of Types of sealers,-H/-NCO the molar ratio, reaction time and reaction temperature were studied. The results show that the best reaction conditions is setting the-H/-NCO equal1.9:1, Diethyl malonate and methyl ethyl ketone oxime as blocking agent to close the remaining isocyanate groups. Unreacted isocyanate groups were blocked by cross-linking reaction with trimethylolpropaneto get the One-component polyurethane coating bindersThe One-component polyurethane coating binders will be mixed with additives preparation of polyurethane coatings in order to spray on the surface treated silicone rubber. After140℃curing1h, the polyurethane coating of silicone rubber surface with highly protective are formed. Test the performance of the coating, such as adhesion, hardness, alcohol resistance, resistance to hand sweat, solvent resistance, resistance to yellowing and other. After the test, resistance to ethanol, the number of more than150, the number of methanol tolerance more than150,5B adhesion, resistance to hand sweat4B, the hardness of2H,160℃for storage1h yellow changed to meet the performance requirements. These results suggest that single component polyurethane can be successfully used in the surface coating of silicone rubber, and will be for its outstanding performance, convenient construction conditions and at low cost and quickly occupied the market.