The heat resistance of Pet Preform used in our daily life is not very good. This problem is very headache for us. Jilian molds provide measures to improve the heat resistance of pet preforms.
1 preform injection cooling time control. Strictly control the cooling time of the preform injection, so that the preform can be demolded as soon as possible. This shortens the molding cycle and increases the yield, and induces globular crystallization due to the higher residual temperature. The crystal diameter of the spherical crystal is extremely small (only 0.3 mm to 0.7 mm) and does not affect the transparency.
2 Choose a reasonable preform and bottle design. The optimized preform shape design and bottle mold design help to improve the wall thickness distribution of the bottle and avoid distortion or shrinkage deformation in different areas of the bottle body;
3 Strictly control the injection and draw-blow process parameters and the temperature distribution of each zone to prevent the residual stress from being released at the PET glass transition temperature (>75 °C) and cause the bottle to deform.
4 cycle blowing technology. When using a hot blow mold, how to control the deformation of the bottle after demolding is essential. Before blowing the mold, the air is blown into the air and circulated, and the bottle body is cooled and shaped to control the amount of deformation after demolding. The intake air of the circulating cooling air passes through the same passage as the initial blowing and the secondary blowing, but is exhausted from the small hole of the head of the drawing rod through the drawing rod. The cycle blowing time is about 0.5 seconds to 2 seconds. Therefore, the high-pressure air consumption of the heat-resistant bottle bot is much higher than that of the ordinary bottle bot.
5 blowing bottle mold temperature control technology. The blowing mold is usually heated by the hot oil circulation method, and the blowing mold is adjusted in three cycles: the bottom of the bottle is cooled. Keep the bottom of the bottle at a low temperature (10 ° C ~ 30 ° C), to avoid excessive crystallization of the unstretched bottom of the bottle and whitish.
Bottleneck temperature adjustment (optional). The non-crystalline bottle mouth portion is completely cooled after being released from the injection mold. Most of the non-crystalline bottle mouths are designed with a reinforced bottle mouth (increasing the wall thickness of the bottle mouth) to improve the sealing performance and avoid deformation of the bottle mouth during the capping process. Usually, the ovality of the bottle mouth after filling is controlled within 0.2 mm, and the outer diameter shrinkage of the thread is less than 0.6%.
The bottle is hot oil circulating. The blow mold was heated to 120 ° C to 145 ° C. Thus, the temperature difference between the preform and the blow mold cavity is reduced to promote further crystallization. Extend the holding time of the blowing bottle so that the bottle wall and the cavity are in contact for a long time and have sufficient time to increase the crystallinity of the bottle to about 35% without destroying the transparency. The mold temperature below 100 °C has little effect on the crystallinity of the bottle body because the crystallisation of the bottle body occurs above 100 °C.
If you want to get reliable pet products, you should choose a reliable China Pet Bottle supplier. Among them, Jilian Plastic is your good choice. Welcome customers to leave us a message. I believe we can make you satisfied.