Coating Solutions for Injection Molding

During the injection molding process, the coating has a great impact on the adhesion of the coating. Before the surface treatment, we must carry out necessary preliminary treatment to improve the bonding strength of the coating. Let's talk about the solution of coating during injection molding.

1. Degreasing of plastic products for injection molding. Similar to the degreasing of metal products, degreasing of plastic products for injection molding can be done by cleaning with organic solvents or degreasing with alkaline aqueous solutions containing surfactants. Organic solvent degreasing is suitable for cleaning paraffin, beeswax, fat and other organic dirt from the plastic surface. The organic solvent used should not dissolve, swell or crack the plastic. It has a low boiling point, is volatile, non-toxic and non-flammable.

2. Activation of the surface of plastic products for injection molding. This activation is to increase the surface energy of plastics for injection molding, that is, to generate some polar groups or coarsen the surface of plastics for injection molding, so that the coating can be more easily wetted and adsorbed on the surface of the parts. There are many methods for surface activation treatment. Among them, the most widely used is the chemical crystal oxidation treatment method, which often uses chromic acid treatment liquid, and its typical formula is 4.5% potassium dichromate, 8.0% water, and 87.5% concentrated sulfuric acid (above 96%).

3. In order to obtain high-quality coating, some injection molding processes also use chemical oxidation treatment. For example, after degreasing, ABS plastic can be etched with a relatively dilute chromic acid treatment liquid. Its typical treatment formula is 420g/L chromic acid and 200ml/L sulfuric acid (specific gravity 1.83). The typical treatment process is 65℃70℃/5min10min, water washing, and drying. The advantage of etching with chromic acid treatment liquid is that no matter how complex the shape of the plastic product is, it can be treated evenly.

Qingdao Xueyu Molding Products Co., Ltd. is mainly engaged in the design and manufacturing of injection molds, injection molding and secondary processing (spraying, pad printing, ultrasonic welding, stamping), etc. For more information about injection molding, please contact us.

Website: www.xyzmould.com

Address: No.18 Henan Head Road, Henan Head Community, Jihongtan Street, Qingdao Industrial Park, Shandong Province, China

Email: wangmiaotian8@163.com