How to improve the yield of TPU plastic mobile phone case during injection molding? Discussion on the treatment of oil stain of release agent

n the field of 3C electronic consumer goods such as smart phones, smart watches and smart bracelets, TPU elastomer plastic is widely used in the sheath substrate and strap of mobile phone protective case, smart watch and smart bracelet. Generally speaking, the surface treatment process of TPU is mainly vacuum plating process. In the field of shoe materials, because of its excellent elasticity and wear resistance, TPU plastic soles are widely used in sports shoes, tourist shoes and other soles, and vacuum electroplating process is also used.

TPU plastic mobile phone case

But in the actual production, the yield of TPU electroplating is not high, which leads to the increase of defective products and bad products, and the increase of cost, which is a headache. How to improve the yield of TPU mobile phone case? In this regard, we consulted Zhang Gong, who has many years of practical experience in China Plastics chemical high performance materials company. Zhang Gong summarized the experience of practical production and application and analyzed it to us: in the TPU electroplating process, the degreasing degree of pretreatment is directly related to the yield problem after electroplating, and the main reason for poor TPU electroplating lies in the degreasing link of TPU plastic surface.

First of all, let's see why there is oil pollution on the surface of TPU plastic?

It turns out that the oil pollution on the surface of TPU plastic mainly occurs in the molding process. When the TPU protective sleeve is molded by injection molding, it needs to be injected through the mold, and then the injection molding product is demoulded. In order to better ensure the yield of injection molding and the efficiency of demoulding, it is generally carried out by spraying oil-based or neutral release agent on the mold, which will cause the release agent on the TPU plastic material, thus forming oil stains. The adhesion of these oil stains is very high, even if the surface is cleaned regularly, it can not be removed.

So, how to deal with the grease of release agent after TPU injection molding?

In the vacuum electroplating industry, the traditional way to treat the oil pollution on the surface of TPU plastic is to soak with white electric oil and clean with degreasing powder. This method is inefficient and unclean. At the same time, white electric oil will lead to hidden safety problems. With the continuous development and innovation of electroplating degreasing technology, TPU oil stain treatment agent has emerged, which makes it possible to cover the oil by spraying, solve the oil spots and oil spots in vacuum electroplating after spraying UV primer caused by oil stains such as release agent, and promote the adhesion of UV primer.

In addition to covering power, TPU oil treatment agent also has elastomer resin with the same composition as TPU material, which can achieve molecular level penetration and play a dual role in improving oil removal and adhesion. The application method is as follows: first, clean the material surface with white electric oil, and then spray TPU oil stain treatment agent. The film thickness is controlled at 3-5 μ m and baked at 65 ℃ for 3-5 minutes. If the electroplating line does not have baking conditions, wet spray wet process can be adopted, and then UV primer can be sprayed to carry out vacuum electroplating.

If the degreasing process of TPU protective sleeve is completed, the yield of electroplating will be greatly improved, so that the cost will be reduced, the efficiency of the factory will be greatly improved, and the income of each employee can be improved accordingly.