Generally, the rubber stopper for injection is coated with thermoplastic olefinic resin. This type of rubber stopper is highly effective for preventing leaching of impurities and bacteria from the drug, but it is not a perfect packaging component for fragile drugs. Therefore, there is a need to improve the physicochemical properties of the rubber stopper.
A cured coating layer may be applied on the surface of the rubber stopper to partially or fully coat the stopper. The coating can be formed by keeping the stopper in a room temperature for about three to fourteen days. The cured coating layer is chemically stable in different environments. This cured coating layer prevents the adhesion of impurities and viruses. It also provides excellent lubricating properties.
One method of curing a fluorine-containing elastomer is to dissolve the elastomer in a solvent such as ethyl acetate. The solution is then heated at a temperature of about 80deg to 250deg C. Then the fluorine-containing elastomer coating can be applied on the rubber stopper. It has improved lubricating properties and heat resistance.
Another method for obtaining a cured coating layer is to use a graft copolymer. The graft copolymer is made from the reaction of polymer segments. The graft copolymer has excellent chemical resistance and is obtained by copolymerization of siloxane with an amino group. This cured elastomer coating layer can be cured by heating or by using a curing accelerator. It is recommended that the concentration of the polymer is not less than about 20 wt.%).
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