Commonly Used Medical Injection Molding Materials
There are over 90 types of polymer materials used in medical injection molding products. Plastics, with their excellent properties, reliable performance, and convenient molding processes, have gained increasingly widespread application in the medical field, making the manufacture of medical supplies from plastic materials a promising prospect. Below are some major categories of commonly used medical injection molding materials.
**Polyvinyl Chloride (PVC)**
PVC is a commonly used raw material in the manufacture of medical plastic products, accounting for more than 25% of the total usage of medical plastics. This resin has low cost, a wide range of applications, is easy to process, and has good chemical resistance, mechanical properties, and electrical properties, but its light and heat stability are poor. Modified PVC plastics can be widely used to manufacture blood bags, blood transfusion bags, blood catheters, artificial peritoneum, cardiac catheters, and other products.
**Polyethylene (PE)**
Including LDPE, HDPE, UHMWPE, etc.
LDPE is low-density polyethylene. Primarily used for blending with other plastics to produce medical packaging bags and intravenous injection containers, it can also be made into high-temperature sterilizable medical plastic bags.
HDPE is high-density polyethylene. It possesses good mechanical properties and is used in artificial lungs, tracheas, larynxes, kidneys, urethras, bones, orthopedic repair materials, and disposable medical supplies. It can also be used as a filler to improve the flow properties of products.
UHMWPE is high molecular weight polyethylene. It has good chemical stability, abrasion resistance, corrosion resistance, and bioinertness, making it a good material for manufacturing artificial lungs and joints.
Polypropylene (PP)
Medical-grade PP should meet requirements such as high purity, non-toxicity, non-irritation, good chemical stability, non-degradability, non-inflammatory, non-allergenic, good biocompatibility, non-carcinogenicity, and non-hemolysis and coagulation. It must also be able to withstand ethylene oxide sterilization.
Polytetrafluoroethylene (PTFE)
PTFE is the primary fluoroplastic used in plastics. It possesses high crystallinity, a very low coefficient of friction, excellent heat resistance, and high chemical stability. This material is resistant to acids, alkalis, and various organic solvents, and is virtually insoluble in all solvents. PTFE also exhibits high-temperature resistance. Its low coefficient of friction makes it suitable for lubrication and also makes it an ideal coating for easy-cleaning cookware and the inner lining of water pipes.
It offers excellent sealing properties, high lubricity and non-stickiness, electrical insulation, good aging resistance, and excellent temperature resistance (able to operate continuously at temperatures from 250℃ to -180℃). PTFE itself is non-toxic to humans.
It has one of the best aging lifespans among plastics. It has the lowest coefficient of friction among solid materials, only 1/5 that of polyethylene. It has the lowest surface tension among solid materials, and does not adhere to any substances. It is physiologically inert, and its use as artificial blood vessels and organs for long-term implantation has no adverse effects. It can be used as a substitute for arteries, veins, and heart membranes in the human body; endoscopes, forceps catheters, tracheas; and other medical devices such as tubes, bottles, and filter cloths. Polytetrafluoroethylene (PTFE) has poor radiation resistance and degrades upon exposure to radiation.
Polyurethanes: Thermoplastic Polyurethane (TPU)
Thermoplastic polyurethane possesses good transparency, high strength and tear resistance, chemical resistance, and abrasion resistance. This resin also has a wide hardness range, a smooth surface, resistance to fungi and microorganisms, and high water stability. These advantages make thermoplastic polyurethane suitable for medical tubing, oxygen masks, catheters, and drug delivery equipment.
Polycarbonate (PC)
The typical characteristics of polycarbonate are toughness, strength, rigidity, and resistance to heat steam sterilization. These characteristics make polycarbonate a preferred choice for blood dialysis filters, surgical tool handles, and oxygen cylinders.
Polyphenylene terephthalate (PET)
PET's excellent chemical and physical properties also lie in its good adaptability to modification treatments. Currently, various modified PET materials are available to meet the diverse needs of the medical plastics market.
Other materials:
Medical injection molding materials also include sulfones, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), and polyimide.
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