| The peelable coating is a kind of functional coating which can protect the substrate surface temporarily,which has widely used in local electroplating,surface protection,chemical milling protection and so on.It plays the role of anti-fouling,anti-rust,anti-acid and alkali and so on.Common peelable protective coatings include acrylic emulsion,polyurethane emulsion,silicone resin,chloroprene rubber and so on.However,it is difficult for single component peelable coatings to have good adhesive properties,tensile strength,elasticity and chemical resistance at the same time.In this paper,epoxy or silicone rubber is used to modify the peelable coating of styrene-butadiene rubber.The purpose of this paper is to improve the peeling strength of styrene-butadiene rubber without affecting its tensile strength and chemical resistance,the feasibility of its application in local electroplating and micro-arc oxidation was also investigated.The main tasks are as follows:1.Study of peelable epoxy-modified styrene-butadiene rubber coating materialWe prepared a peelable coating by epoxy with excellent adhesive property modified styrene-butadiene rubber,the effects of epoxy adhesive ratio and curing conditions on the mechanical properties,chemical resistance and high temperature resistance of the coatings were studied.The results showed that compared with the unmodified styrene-butadiene rubber peelable coating,the 1800°peeling strength of the coating prepared with 5%of epoxy with respect to the mass of styrene-butadiene rubber solution increased from 0.00 kN/m to 0.93 kN/m,the tensile strength changed from 15.67 MPa to 13.56 MPa and the elongation at break changed from 436%to 510%.The variation of mass of coating in 6 wt%NaOH solution,33 wt%HNO3 solution,or 90 ?water for 5 min were 0.05%,0.23%,and 0.18%,respectively(equivalent to that before modification).After alkali washing,pickling and hot water washing,the adhesion of the modified coating is still good.Finally,the coating has a good protective effect in the practical application of local gold plating on aluminum workpieces.2.Study of peelable silicon rubber-modified styrene-butadiene rubber coating materialWe prepared a peelable protective coating by silicon rubber modified styrene-butadiene rubber,which combined good adhesive property of silicone rubber and high tensile strength of styrene-butadiene rubber.The effects of silicone rubber content and solvent content on the properties of peelable coatings were studied.Using aniline methyl triethoxysilane as compatibilizer,the effects of compatibilizer and curing conditions on the mechanical properties,chemical resistance,high temperature resistance,adhesion and operation process of the coatings were investigated.The results showed that pure silicone rubber could not be peeled off after bonding aluminum sheet,and there was basically no adhesion of pure styrene butadiene rubber.However,when styrene-butadiene rubber:silicone rubber is 1.5:1,the peelable coating shows excellent thixotropy,and has the characteristics of no flow hanging after being coated;and the coating has the best mechanical property,good stripping property,no residue after peeling.Further,the phenylamine methyl triethoxysilane(6%)is added as a compatilizer,so that the compatibility of the styrene-butadiene rubber and the silicon rubber can be improved,the 1800°peeling strength of the coating increased from 0.20 kN/n to 0.22 kN/m,and still has high tensile strength.The variation of mass of coating in 6 wt%NaOH solution,33 wt%HNO3 solution,or 90 ? water for 5 min were 0.12%,0.17%,and 0.12%,respectively(equivalent to that before modification).The adhesion of the modified coating was not affected by the micro-arc oxidation for 20?40 min at the voltage of 550?700 V and the electricity of 100?150 A.Finally,the modified peelable coating has excellent protective effect in the practical application of local micro-arc oxidation of aluminum to alumina ceramic film. |
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