Natural Rubber(NR) Overview
At present, there are many types of medical rubber materials, including natural rubber and various synthetic rubbers. Among them, silicone rubber and butyl rubber are the most widely used and researched.
At present, medical rubber products mainly include: medical silicone rubber catheters, medical hoses, pure hoses, medical rubber stoppers, medical infusion rubber stoppers, antibiotic rubber stoppers, antibiotic stoppers; vaccine stoppers, butyl albumin stoppers , Butyl rubber bottle stoppers, medical air cushions, sterilized rubber medical gloves, disposable rubber examination gloves, artificial silicone organs, etc.
Natural rubber is the first medical elastomer used. Because it contains a highly allergenic vegetable protein, the compounding agent N-nitrosamine has a greater irritation response to the human body. Only after purification and modification can it be used in the human body.
The purification of natural rubber mainly uses deacidified protein purification method. The purified natural rubber needs to choose a suitable vulcanization system, such as organic peroxide vulcanization or radiation vulcanization to make the required rubber products. Natural rubber has excellent elasticity and is widely used in various medical products such as tubes, belts, plugs, gloves, and condoms; however, it has poor resistance to biological aging and is generally used in in vitro medical rubber products.
Currently, there is overcapacity of domestic natural rubber latex. Due to the strict control of natural rubber latex medical products abroad, domestic natural rubber products must accelerate the development and production of low protein content, and at the same time strengthen the development of domestic and foreign markets.
Polyurethane is a polymer material between general rubber and plastic. It has the high elasticity of rubber and the high strength of plastic. It has a wide range of hardness, excellent abrasion resistance, and outstanding biocompatibility, especially anticoagulation. It is mostly used as a blood pump material for artificial hearts.
According to the different hard segments of the material structure, polyurethane can be divided into three generations. The first generation uses aromatic diisocyanate as the hard segment, the second generation uses aliphatic isocyanate as the hard segment, and the third generation uses biodegradable elastomers as the hard segment. Hard segment. The third-generation materials are currently in the research and development stage and have not yet been industrialized, but their application prospects are quite broad.
With the continuous expansion of polyurethane medical products, future development trends include: biodegradable oligosaccharide-derived polyurethane, lignin, tannin and bark-derived polyurethane, cellulose-derived polyurethane, starch-derived polyurethane, etc.; with shape memory function Polyurethane, its working principle is to use the difference between the glass transition temperature of the hard segment and the soft segment to realize the shape memory function. It is mainly used for various orthopedic and conformal products. Its research and development focus is to improve its shape. The accuracy of the restoration temperature; polyurethane for tissue engineering, tissue engineering has been a new direction of rapid development in biomedical engineering. For the field of tissue engineering, some new polyurethanes are in the research stage, such as ionic polyurethane, surface porous polyurethane, and co-polyurethane. Hybrid polyurethane, bio-specific identification polyurethane, etc., are mainly used in tissue engineering technology fields such as blood transfusion, burns, diabetes and cardiovascular; in the field of antibacterial materials, in the future, antibacterial polyurethane soft foam and antibacterial polyurethane resin will become the hotspot of medical polyurethane development. .
At present, the domestic medical polyurethane industrialization is relatively small, and many units have conducted medical polyurethane research, such as Shanxi Research Institute of Chemical Industry, Sun Yat-sen University, Shanghai Rubber Products Research Institute, Jiangsu Chemical Industry Research Institute, etc., have developed some thermoplastic medical polyurethanes Some products such as film and body temperature shape memory polyurethane have been industrialized.
The main chain of silicone rubber polymer is composed of Si-O-Si bonds. Its helical structure makes the polarities of the silicon-oxygen bonds cancel each other, and the side chains are generally low-polar or non-polar groups, so the entire macromolecule The polarity is very low, so that the silicone rubber exhibits hydrophobicity, oxidation resistance and aging resistance. In addition, the polarity of the Si-O bond in the main chain and the Si-C bond in the side chain are similar to ionic bonds. Under normal use temperature (below 250°C), cracking, oxidation and other reactions will not occur, so it has excellent Heat resistance.
Because of its physiological inertness, non-toxicity, and no adhesion to other materials, it can withstand many times of steaming and sterilization, and can be widely used in medical and health care. Due to the small intermolecular force of silicone rubber, its film has better air permeability than ordinary rubber and plastic waxing film, and has strong selectivity for different air permeability, so it can be used as a gas exchange membrane for medical supplies and in vivo Artificial organs, etc.