Plastic rubber has long been one of the important raw materials for medical equipment and pharmaceutical packaging. With the vigorous development of the industry, various high-performance plastics and technologies for medical devices have emerged. In addition to traditional medical plastics, such as PP, PVC, PE, and silicone rubber, which are commonly used in the medical device industry, some high-performance materials are important materials to promote the development of the medical device industry.
Market Development of Medical Plastics:
Products made of plastic materials have already penetrated our lives. Humans are accustomed to plastic things, and because of the advancement of technology, plastic materials are more optimized to meet the requirements of temperature, environment, structure, and so on.
In daily life, almost 98% of daily products are made of plastic materials, and plastic products are very mature. However, for medical care, related products have different requirements, because the objects used are relatively weak, no matter the design, safety must be the priority, and the consideration of green environmental protection must be considered.
Plastic materials facilitate the development of medical devices and breakthroughs in manufacturing. Compared with other materials, plastic materials are light in weight, low cost, easy to process, elastic and non-ferrous properties (providing safety for MRI irradiation), and excellent biocompatibility, medical polymers have been widely used in medical design. These advantages make it easier to develop next-generation implants, disposable single-use devices, packaging technologies, and the like. Global demand for medical polymers has reached nearly 5 million metric tons and is expected to continue to grow and exceed 7 million metric tons.
What is the Development Advantage of Medical Plastics?
- The cost is low, it can be reused without sterilization, and it is suitable to produce disposable medical devices.
- The processing is simple, and its plasticity can be used to process into a variety of useful structures, while it is difficult to manufacture products with complex structures from metal and glass.
- Tough and elastic, not as easily broken as glass.
- It has good chemical inertness and biological safety.
Characteristics of Research and Development and Selection of Plastic Materials:
The demand for plastic materials is slowly increasing in medical products. In the future, when choosing plastic materials to design medical materials, there are several important considerations in the design and selection of medical materials:
- Plastic material resistant to chemical cleaning agents to enhance the service life in the hospital:
Even though hospitals have done their best to reduce the risk of nosocomial infection, nosocomial infection is still high risk and needs to be treated with caution throughout the hospital. To combat nosocomial infections, in addition to using copper metal surface materials, it is more common for hospitals to strengthen the use of disinfectants to clean the surfaces of equipment and equipment. But over time, if the plastic is not strong enough, these devices may begin to corrode, crack, discolor, and even structurally brittle, posing a danger.
- The design of replacing metal materials with plastic materials for medical use has the same or even better performance:
In the design of medical equipment, new medical plastic materials have replaced the metal products of the past. Many engineering plastics perform like metals, have the same tensile strength, but are lighter, cheaper, more flexible, and easier to manufacture. The lightweight plastic product, combined with the ergonomic design the product, makes long surgical procedures easier. Also, plastic injection molding is much cheaper than metal manufacturing.
- Cost control, from raw material to process:
Cost reduction is a concern of manufacturers in all walks of life. Medical device manufacturers around the world, including upstream material suppliers and contract manufacturers, are required to join the ranks of cost reduction. For this reason, some manufacturers use new medical plastic materials and processing technologies to replace the current methods to reduce costs.
- Safe materials, from environmental issues to interference with human health:
Many groups in society continue to promote the issue of environmental protection or human health, which also prompts medical equipment and equipment companies to start paying attention from the production side.
Relevant medical cases such as: Designing products without bisphenol A (BPA). Bisphenol A is one of the components of polycarbonate (PC), a commonly used medical-grade thermoplastic polymer. When polycarbonate degrades, bisphenol A will be precipitated. Its chemical structure is like estrogen. It may become a biological hormone or endocrine disruptor. It may also cause cancer and cause problems in human development and behavior. Exposure to BPA is therefore a general concern, such as beverages in jugs made of PC, foods that meet polymers, and intravenous injection devices that use PC parts. Based on these concerns, to ensure the safety of infants and young children, Taiwan has revised the hygiene standards for food utensils and containers and completely banned the manufacture and sale of baby bottles containing bisphenol A materials. A safety review report by the FDA and Health Canada concluded that there is no minimum safe dose of BPA.
The government and relevant safety inspection units are also increasingly concerned about issues of environmental protection, environment, and human safety, and are also promoting relevant policies. Various medical device manufacturers are also developing and manufacturing production processes to gradually improve related medical plastic applications.
- Bioabsorbable materials, used in various implant designs:
Bioabsorbable polymers have been around for a long time, but they have only been used in medical devices in recent years. These materials will degrade over time and be safely absorbed and excreted by the body. Its new applications are currently in the field of drug delivery (eg: drug-coated stents), bone augmentation and fixation (eg: bone nails), and soft tissue regeneration and replacement (stents).
What are the Benefits of Bioabsorbable Materials?
For bone plates and pins used in orthopedics, if absorbable materials are used to replace the traditional titanium alloys when the bones heal, the materials will slowly melt, eliminating the need for subsequent surgery to remove the implants, thus reducing the cost of surgery and risk of infection.
Most bioabsorbable materials are based on polyester, and there are two common materials, polylactic acid (PLA) and polyglycolic acid (PGA). Another new material is polyglycerol sebacate (polyglycerol sebacate, or PGS). PGS can be customized for different applications, such as repair scaffolds for bones, fibers for bio textiles, and coatings on implant surfaces. In addition, PGS does not trigger an immune or inflammatory response in patients.
What are the Commonly Used Medical Plastics?
- Polyvinyl chloride (PVC):
PVC is one of the most produced plastic varieties in the world. PVC resin is a white or light-yellow powder, pure PVC is atactic, hard, and brittle. According to different uses, different additives can be added to make PVC plastic parts show different physical and mechanical properties. Adding an appropriate amount of plasticizer to PVC resin can make a variety of hard, soft, and transparent products. Hard PVC does not contain or contain a small number of plasticizers, has good tensile, flexural, compressive, and impact resistance properties, and can be used alone as a structural material. Soft PVC contains more plasticizers, and its flexibility, elongation at break, and cold resistance increase, but brittleness, hardness, and tensile strength decrease.
About 25% of medical plastic products are PVC. This is mainly due to the low cost of the resin, its wide application range, and its ease of processing. PVC products for medical applications include hemodialysis tubing, breathing masks, oxygen inhalation tubes, etc.
- Polyethylene (PE):
Polyethylene plastic is the most productive variety in the plastics industry, milky white, tasteless, odorless, and non-toxic glossy waxy particles. It is characterized by low price and good performance and can be widely used in industry, agriculture, packaging, and daily industry.
PE mainly includes LDPE, HDPE, and UHDPE. HDPE has fewer branches on the polymer chain, higher relative molecular mass, crystallinity and density, higher hardness and strength, poor opacity, and higher melting point. It is often used in injection molding parts. LDPE has many branches, so the relative molecular weight is small, the crystallinity and density are low, and it has good flexibility, impact resistance, and transparency, and is often used in blown film. UHDPE has high impact strength, low friction, stress crack resistance, and good energy absorption properties, making it an ideal material for an artificial hip, knee, and shoulder connectors.
- Polypropylene (PP):
Polypropylene is colorless, odorless, and non-toxic. Looks like polyethylene, but is more transparent and lighter than polyethylene. PP is a thermoplastic with excellent properties, with the advantages of small specific gravity, non-toxicity, easy processing, impact resistance, and flex resistance. It has a wide range of applications in daily life, including woven bags, films, turnover boxes, wire shielding materials, toys, car bumpers, fibers, washing machines, etc. Medical PP has high transparency, good barrier properties, and radiation resistance, making it widely used in medical equipment and packaging industries. Non-PVC material with PP as the main body is a substitute for the widely used PVC material.
- Polystyrene (PS) and K resin:
PS is the third-largest plastic variety after polyvinyl chloride and polyethylene. It is usually processed and applied as a one-component plastic. Use plastics, electrical parts, optical instruments, and cultural and educational supplies. The texture is hard and brittle and has a high coefficient of thermal expansion, which limits its application in engineering. In recent decades, modified polystyrene and styrene-based copolymers have been developed to overcome the shortcomings of polystyrene to a certain extent, and K resin is one of them.
K resin is made by copolymerization of styrene and butadiene. It is an amorphous polymer, transparent, odorless, and non-toxic. The amount of butadiene contained in the K material is different, and its hardness is also different. Because the K material has good fluidity and a wide processing temperature range, its processing performance is good. The main uses in daily life include cups, lids, bottles, cosmetic packaging, hangers, toys, PVC substitute products, food packaging, and medical packaging supplies.
- Acrylonitrile Butadiene Styrene copolymers (ABS):
ABS has certain rigidity, hardness, impact and chemical resistance, radiation resistance, and ethylene oxide sterilization resistance. The medical application of ABS is mainly used as surgical tools, roller clips, plastic needles, toolboxes, diagnostic devices, and hearing aid shells, especially the shells of some large medical equipment.
- Polycarbonate (PC):
Typical properties of PC are toughness, strength, rigidity, and heat-resistant steam sterilization, which make PC the preferred choice for hemodialysis filters, surgical tool handles, and oxygen tanks. Medical applications of PC also include needle-free injection systems, perfusion instruments, blood centrifuge bowls, and pistons. Taking advantage of its high transparency, the usual myopia glasses are made of PC.
- Polytetrafluoroethylene (PTFE):
PTFE resin is a white powder with a waxy appearance, smooth and non-stick, and is the most important plastic. PTFE has excellent performance, which is beyond the comparison of general thermoplastics. Its friction coefficient is the lowest among plastics, and it has good biocompatibility. It can be made into artificial blood vessels and other devices that are directly implanted into the human body.