Micro-Injection Molding And Products Testing For Cosmetic Polymer Micro-Needle

Micro-needle is a new administration mode between transdermal patch and subcutaneous injection, which can be fast and painless, and can transfer macromolecular drugs. Polymer micro-needle has a wide range of optional materials, good biological compatibility and low cost, is suitable for mass production. In this paper, solid polymer micro-needle as a research object, numerical simulation was carried out with ANSYS. Injection molding process of micro-needle was simulated by Moldflow; PC micro-needle was prepared by means of micro-injection, and injection molding process was analyzed by orthogonal experiment. Finally, the performance of PC micro-needle was verified in vitro transdermal experiment, specific studies are as follows:(1) The mechanical calculation of micro-needle was performed. The stress of three groups of PC micro-needle with different size was simulated by ANSYS, the stress and strain of micro-needle when it piercing the skin was investigated. Finally, the conic needle structure was determined under micro-injection conditions, the tip diameter was 30μm, bottom diameter was 100μm and height is 350μm. To verify the feasibility of polymer micro-needle in theory, the strength of PC, PMMA, PS and PL A micro-needle was verified.(2) Injection molding process of PC micro-needle was simulated with Moldflow, the effect of the runner and mold cavity structure on product performance was analyzed, the simulation results show that products with single runner structure had the best performance. Micro-needle with rectangular and circular array had no obvious difference of influence on the molding process and the products.(3) PC micro-needle was prepared by means of micro-injection, and the process parameters were obtained. Four factors, including injection speed, injection pressure, melt temperature and packing pressure, three levels orthogonal test was finished. The results show that the most important factor to affecting the quality of products was melt temperature; the second was the injection speed; injection pressure and holding pressure were weakest.(4) The strength of PC micro-needle was verified in vitro transdermal experiment to ensure it could be pierced into the skin without breaking or bending. And experiments results show that the needle could deliver effective ingredients to the deeper layers of the skin, and promote the skin absorption effectively.