Thermoplastic polyolefin elastomer based on EPDM+PP, material hardness: Shore A92±3; it can be molded like thermoplastics, such as polyethylene, polypropylene, etc., by injection molding, extrusion, blow molding, etc. on conventional plastic molding machines. The shelf life of the material: 3 years; the storage temperature of the material: indoor -20 ℃-40 ℃; the instructions for the use of the blow molding product are as follows.
Ⅰ. Drying of thermoplastic rubber TPV
It is necessary to dry TPV before blow molding. The recommended drying conditions are: the temperature is 115±10℃, the time is more than 2 hours, the temperature is high in winter, and the temperature is low in summer; if the vacuum packaging is broken, it is recommended to increase the drying time to more than 4 hours.
For northern regions, the drying time can be slightly reduced. For the humid regions in the south, special attention should be paid to ensuring dryness in spring and summer, and vacuum-packed materials should be used as much as possible.
Insufficient drying will cause the tube blank to be easily blown, the tube blank is biased, there are pores inside the tube blank, and the inner surface of the blow molded product is not smooth and rough.
Ⅱ. Temperature of barrel screw and die head of thermoplastic rubber TPV
1. Molding process: blow molding products;
2. Relying on the hopper: 170±10℃;
3. Middle: 180±10℃;
4. Front: 180±10℃;
5. Die head: 175±10℃.
Generally speaking, the temperature of the extruded tube blank is smooth and the extrusion of the tube blank is stable. For the tube blank with a slightly longer extrusion length, in order to avoid the thinning of the tube blank, the temperature of the barrel screw can be slightly reduced, especially the mold head temperature. If the temperature is too low, the gloss of the extruded tube blank will be poor.
Ⅲ. Mold temperature of thermoplastic rubber TPV
The mold temperature is generally recommended to be below 40 °C. Lowering the mold temperature is helpful for product shaping and demolding speed, but it will affect the fusion strength and appearance of the batch front, which needs to be balanced by the customer.
Ⅳ. The use of thermoplastic rubber TPV back material
The scraps can be reused after being crushed. It needs to be dried before use. The addition amount is generally not more than 30%, which has no effect on performance. However, for the tube blank or product that has just been extruded, please do not recycle it for reuse. After adding, it may cause the appearance of the product to have non-plasticized pitting, etc.
Ⅴ. Use of release agent for thermoplastic rubber TPV
For products with difficult demoulding, it is recommended to use a release agent, but the spraying of the release agent should be uniform, especially not too much spraying on the core and the parting line of the mold, which may cause the strength of the weld to deteriorate and the product Easy to crack.
Ⅵ. Blowing pressure of thermoplastic rubber TPV
Generally, it is 0.4-0.7Mpa. For products with corrugations, the long corrugations should be low, and the short corrugations should be high.
Ⅶ. Blowing time of thermoplastic rubber TPV
It should be determined according to the size and appearance of the product. If the shrinkage of the product is too large, the blowing time will be extended, generally between 6 and 9 seconds.
Ⅷ. Thermoplastic rubber TPV shutdown treatment and barrel cleaning
Generally, the shutdown time does not exceed half an hour, so you don't need to turn off the heating. If the shutdown is for a long time, please turn off the heating. The best way is to clean the barrel with polyethylene after shutdown, and it is better to basically squeeze out the TPV remaining in the barrel. This is convenient for the next startup and reduces the waste generated by startup.