Methods to improve the heat resistance of bottle preforms

In the process of producing plastic bottles, the process control of the bottle blank is very strict. If you want the quality of the bottle to be good, you need to improve its heat resistance, mainly based on the control of injection cooling time, the selection of reasonable design, strict control of injection and drawing, circulation blowing technology, and the application of blowing mold temperature control technology, etc.

1. Control of cooling time for preform injection

Strictly control the injection cooling time of the preform to allow for early demolding. This can shorten the molding cycle and increase production, while also inducing spherical crystallization due to higher residual temperatures.

2. Choose appropriate bottle preforms and bottle designs

Optimized preform shape design and preform mold design can help improve the wall thickness distribution of the bottle and avoid distortion or shrinkage deformation in different areas of the bottle body.

3. Strictly control injection and casting

The blowing process parameters and temperature distribution in each area are used to avoid residual stress release at the PET glass transition temperature, which may cause deformation of the preform.

4. Circular blowing technology

It is crucial to control the deformation of the bottle after demolding when using a hot blow bottle mold. Before opening the bottle blowing mold, air is blown in and circulated to cool and shape the bottle body, thereby controlling the deformation after demolding. The intake of circulating cooling air passes through the same channel as the initial and secondary blowing, but is discharged from the small hole at the head of the billet rod through the inside of the billet rod.

5. Application of Temperature Adjustment Technology in Bottle Blowing Mold

Usually, the hot oil circulation method is used to heat the blow molding mold, and there are three types of temperature control cycles for the blow molding mold: bottom cooling water circulation. Maintain a low temperature of 10 ℃ -30 ℃ at the bottom of the bottle to avoid excessive crystallization and whitening of the unstretched bottom.