Basically, TPX release film is a material with good fluidity and can be formed using the same molding method and equipment as PE and PP. As it is a transparent material, if other materials are mixed in, it will significantly reduce transparency. When dyeing, dry mixing method can be used, but pigments must be selected that can withstand molding and processing temperatures.

injection moulding

a. Forming machine

The injection molding of TPX release film can use a molding machine for polyolefin with appropriate heating capacity and temperature control mechanism. The molding temperature range is wide, and can be formed between 270-330 ℃ with small internal deformation. To obtain good product properties, high-temperature molding should be adopted, and the mold temperature is 20-80 ℃. TPX, like PP, is a thermal decomposition type material that will decompose under prolonged heating. Therefore, the capacity of the molding machine should be appropriate. When the injection capacity is too large relative to the weight of the product, it will not be able to obtain good products. The melting point viscosity of TPX release film is low, and it will flow out from the nozzle, so a closed nozzle should be used. If a flat nozzle is used, the temperature should be carefully controlled.

b. Mold construction

The basic structure of the mold is roughly the same as PP, with the following differences:

Surface grinding: TPX release film has good flowability, and in order to make the product highly transparent and glossy, mirror grinding is necessary.

Demolding: The TPX release film will become soft at higher temperatures, and the ejection sheath may break the product. It is advisable to use an ejection plate and air to eject it together.

Exhaust: The molding temperature is high and gas is easily generated, so there must be a sufficient exhaust structure.

Shrinkage rate: It varies depending on the shape and thickness of the product under different molding conditions, usually ranging from 1.5 to 2.5%.

c. Forming conditions

Depending on the molding conditions, the shrinkage rate of TPX release film and the degree of resin coordination within the product can also change, and even affect the practical physical properties of the product. The molding shrinkage rate varies depending on the resin temperature, mold temperature, injection rate, and time. The higher the molding temperature, the smaller the shrinkage rate, and the difference in shrinkage rate between the flow direction and the right angle direction is also reduced, resulting in good products. The molecular weight of TPX release film is large, about 400000 to 1.2 million, but the intermolecular force is weak, making it easy to flow. Although the temperature is reduced and sufficient molding pressure is applied, it can still be formed. However, due to the resin coordination inside the product, the resulting product is brittle and prone to cracking. The focus of TPX release film injection molding is to reduce the molecular coordination inside the product, so the resin flow rate (injection speed) in the mold should be slow and the resin viscosity should be reduced (high-temperature molding). Those with slower ejection speed have a wide range of suitable conditions.