Research On Roughening Without Chromium And Activating Without Palladium Of PA6 Substrate

Nylon-6?PA6?has the advantages of good toughness,high wear resistance,high mechanical strength,good impact strength,high melting point,acid and alkali resistance,and good molding processability.Thus widely used in various fields,but the material itself is not conductive,resulting in a limited application.Electroless plating is a method commonly used in the industry to realize surface metallization of non-conductive materials.The method is low in cost and simple in operation.However,the traditional plastic electroless plating process contains chromium and palladium.The toxicity of chromic anhydride is high and the palladium resource is short.In this paper,a chromium-free roughening and palladium-free activation system suitable for PA6 was developed and the process was optimized.The roughening system,including sulfuric acid,formic acid,acetic acid for PA6 was directly gained by the tests of morphology after the roughening and adhension.The roughening process was optimized to find that the best process was acid concentration of 5 vol% sulfuric acid,10 vol% formic acid,20 vol%acetic acid for 4 min at 35 ?.Under the roughening condition,the contact angle of the substrate surface was decreased from 90° to 49°,and the hydrophilicity was significantly improved.At the same time,the average surface roughness of the sample increased from 199 nm to 407 nm,and the maximum profile height also increased from 1154 nm to 2083 nm.The PA6 surface coating has a good adhesion,and there is almost no shedding in the adhension tests.Through the micromorphology of the SEM,it was found that after PA6 is roughened by this condition,a large number of microcavities with appropriate size and evenly distributed on the surface.It was found by FT-IR that the amide ring of PA6 surface was broken during the roughening process and obtained carboxyl and amino groups.After roughening,a large number of polar groups are generated on the surface of the PA6 substrate,and the metal particles can be captured,thereby introducing the corresponding catalytic metal on the surface of the substrate.In this paper,the activation of ionic copper and the reduction of alkaline NaBH₄ successfully introduced the catalytically active metal on the surface of PA6 substrate.The process was studied by the activation rate,copper distribution and electroless plating.The results showed that when the activation process was 50g·L^-1 CuSO₄,the pH was 3.8,the time was 2 min,the temperature was 50 ?,thereduction process was 50 g·L^-1NaBH₄,20 g·L^-1Na OH,and the temperature was at 50 ?,the activeting effect was better.The activation rate was high,the number of copper particles on the surface was more and evenly distributed,and the electroless plating has obviously no phenomenon of leakage plating,bubbling,and blackening.And compared with the traditonal colloidal palladium activation process,the ion copper activation method studied in this paper found that can achieve the same goal as the colloidal palladium activation,and has a good application prospect.