Medical PP plastics have high transparency, good barrier properties and radiation resistance, making them widely used in medical equipment and packaging. Non-PVC materials based on PP plastics are widely used PVC materials. alternatives.
Medical PP plastic features
PP plastic is colorless, tasteless, non-toxic. Appears like polyethylene, but more transparent and lighter than polyethylene. PP is a kind of excellent thermoplastic, with small specific gravity (0.9g/cm3), non-toxic, easy to process , impact resistance, flex resistance and other advantages.
Main properties of medical PP plastics
High temperature disinfection:
PP plastic is a semi-crystalline material with high melting point and good heat resistance. It can be sterilized at temperatures above 100 ° C. Yield strength, tensile strength, compressive strength, hardness and elasticity ratio polyethylene (PE) ) is high.
Low temperature resistance, impact resistance:
The homopoly PP is more brittle, and the random copolymer PP synthesized with ethylene has better toughness and stronger impact strength. Generally, the products used under low temperature conditions should be copolymerized with PP or thermoplastic rubber. Modification of PP to increase its flexibility and low temperature impact resistance.
Non-PVC large infusion bag is made of copolymerized PP and elastomer blending modified material.
insufficient:
Under the action of oxygen, heat and light, it is easy to depolymerize and age, so it is necessary to add anti-aging agent. PP products are not easy to bond, need to be treated before bonding, and use special adhesive, ring used by equipment factory The ketone can not meet the requirements. The coloring property is poor, the shrinkage rate is large (generally 1.6-2.5%), the burn resistance is poor, and it is easy to catch fire. PP is a non-polar material, and the adsorption amount of the drug is low.
Processing conditions
Processing technology:
It can be injection molded, extruded, blow molded or made into a film. PP film is usually welded into a bag by heat sealing method, and the processing technology is more complicated than the process of welding PVC bags with high frequency. Non-PVC large infusion bag is produced by using automatic equipment. To ensure stable process and reliable quality.
Drying treatment:
Low water absorption, no need for drying treatment.
Melting temperature:
220-270 ° C, please do not exceed 275 ° C. Mold temperature: 40-80 ° C, 50 ° C is recommended.
Injection pressure:
Can be as large as 1800bar.
Injection speed:
High-speed injection molding can be used to minimize internal pressure. If defects occur on the surface of the product, low-speed injection at higher temperatures should be used.
Runners and gates:
For cold runners, typical runner diameters range from 4 to 7 mm. It is recommended to use round inlets and runners. All types of gates can be used. Typical gate diameters range from 1 to 1.5 mm. However, it is also possible to use gates as small as 0.7 mm. For edge gates, the minimum gate depth should be half the wall thickness; the minimum gate width should be at least twice the wall thickness. The PP material can be used with hot runners. system.