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EP-4201434-B1 - MEDICAL RUBBER COMPOSITION, MEDICAL RUBBER PART, AND PACKAGING ARTICLE FOR MEDICAL RUBBER PART

EP4201434B1EP 4201434 B1EP4201434 B1EP 4201434B1EP-4201434-B1

Inventors

  • KIDA, Yogun
  • TAJIMA, KEI
  • NOJIRI, Kazuki
  • MATSUTANI, YUICHIRO
  • ONISHI, TOSHIKI
  • KONDO, TOSHIKAZU

Dates

Publication Date
20260506
Application Date
20221213

Claims (10)

  1. A medical rubber composition containing: a (a) base polymer containing a halogenated isobutylene-isoprene rubber; a (b) polyethylene; and a (c) triazine derivative as a crosslinking agent, wherein a proportion of the triazine derivative contained per 100% by mole of a halogen of the halogenated isobutylene-isoprene rubber contained in the (a) base polymer is 1% by mole to 15% by mole, the proportion of the halogenated isobutylene-isoprene rubber contained in the (a) base polymer is not lower than 90% by mass, and a blending amount of the (b) polyethylene per 100 parts by mass of the (a) base polymer is 3 parts by mass to 30 parts by mass, characterized in that the (b) polyethylene includes high-density polyethylene (HDPE) and low-density polyethylene (LDPE) in combination, and the mass ratio (HDPE/LDPE) of the high-density polyethylene (HDPE) to the low-density polyethylene (LDPE) is not lower than 0.3 and not higher than 5.0.
  2. The medical rubber composition according to claim 1, wherein the halogenated isobutylene-isoprene rubber is at least one rubber selected from the group consisting of chlorinated isobutylene-isoprene rubber, brominated isobutylene-isoprene rubber, and brominated isobutylene-para-methylstyrene copolymer rubber.
  3. The medical rubber composition according to claim 1 or 2, wherein the (b) polyethylene contains a polyethylene having a degree of crystallinity not higher than 70%.
  4. The medical rubber composition according to any one of claims 1 to 3, wherein an amount of the (c) triazine derivative contained per 100 parts by mass of the (a) base polymer component is not smaller than 0.1 parts by mass and not larger than 1.4 parts by mass.
  5. A medical rubber part (1) molded from the medical rubber composition according to any one of claims 1 to 4.
  6. A packaging article (3, 5, 7) for the medical rubber part (1) according to claim 5, the packaging article (3, 5, 7) accommodating a plurality of the medical rubber parts (1), wherein the packaging article (3, 5, 7) has been subjected to sterilization treatment with gamma ray.
  7. The packaging article (3, 5, 7), for the medical rubber part (1), according to claim 6, wherein the packaging article (3, 5, 7) has been subjected to sterilization treatment with the gamma ray such that an absorbed dose of the gamma ray is not lower than 15 kGy.
  8. The packaging article (3, 5, 7), for the medical rubber part (1), according to claim 6 or 7, wherein the packaging article (3, 5, 7) has been subjected to sterilization treatment with the gamma ray such that an absorbed dose of the gamma ray is not lower than 25 kGy.
  9. The packaging article (3, 5, 7), for the medical rubber part (1), according to any one of claims 6 to 8, wherein an oxygen concentration in the packaging article (3, 5, 7) not having yet been subjected to sterilization treatment with the gamma ray is not higher than 5%.
  10. The packaging article (3, 5, 7), for the medical rubber part (1), according to any one of claims 6 to 9, wherein the medical rubber part (1) is a rubber plug for a vial, a cap or a plunger stopper for a syringe, or a rubber plug for a vacuum blood collection tube.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present disclosure relates to a medical rubber composition for sterilization with gamma ray, a medical rubber part sterilized with gamma ray, and a packaging article for the medical rubber part. Background Art Medical rubber plugs for sealing an opening of a syringe, a vial, or the like are required to have many characteristics such asnon-elution characteristics, high cleanability, chemical resistance, resistance to needle piercing, self-sealability, and high slidability. Quality characteristics that are required of the medical rubber plugs should, in terms of use of the medical rubber plugs, comply with the regulations stipulated in "Test for Rubber Closure for Aqueous Infusions" of the 17th edition of the Japanese Pharmacopoeia. For example, Japanese Laid-Open Patent Publication No. H10-179690 discloses a rubber plug for a pharmaceutical agent container, the rubber plug being obtained by blending 5 to 25 parts by weight of fine powder of ultrahigh-molecular-weight polyethylene per 100 parts by weight of halogenated isobutylene-isoprene rubber, and vulcanizing the resultant halogenated isobutylene-isoprene rubber by using at least one of 2-substituted-4,6-dithiol-s-triazine derivatives or by using an organic peroxide, in the absence of a zinc compound. There is an increasing demand for medical rubber products (syringe gaskets, vial plugs, and the like) to be delivered in a state of guaranteeing sterilization thereof, i.e., to be ready-to-use (RTU). Examples of a method for guaranteeing sterilization include methods involving sterilization with high-pressure steam, sterilization with ethylene oxide gas (EOG), and sterilization with gamma ray. The method involving sterilization with gamma ray has an advantage that a medical rubber product can be sterilized while being packaged and thus can be delivered without opening the package. Meanwhile, the method involving sterilization with EOG has environment-related issues. Considering this, the method for guaranteeing sterilization tends to be switched to the method involving sterilization with gamma ray. The method involving sterilization with gamma ray guarantees sterilization by means of absorbed dose setting and actually measured values. If a plurality of medical rubber parts are packed into a packaging bag and sterilization with gamma ray is performed, unevenness among the medical rubber parts might occur in the packaging bag. Thus, even when the packaging bag is irradiated with a predetermined radiation dose of gamma ray, variation in the absorbed dose of gamma ray occurs in the packaging bag. This gives rise to: medical rubber parts having low absorbed doses of gamma ray; and medical rubber parts having high absorbed doses of gamma ray. However, it is necessary to ensure, for each medical rubber part, a minimum absorbed dose with which the medical rubber part can be sterilized. Thus, it is necessary to irradiate the packaging bag with at least the minimum absorbed dose of gamma ray. This gives rise to medical rubber parts that absorb an excessive dose of gamma ray at the time of sterilization with gamma ray, in the packaging bag. Japanese Laid-Open Patent Publication No. 2002-301133 discloses: a rubber composition containing an isobutylene copolymer as a main component and having a density not higher than 0.95, the rubber composition being used for a medical rubber plug or a medical rubber product on which radiation treatment is easily performed; and a crosslinked product of the rubber composition. Japanese Laid-Open Patent Publication (Translation of PCT Application) No. 2017-531604 discloses a method for packaging a part (1), made from an elastomer, such as a plug for a pharmaceutical agent container. The method includes: a step of packing the part (1) into a primary bag (10) made from a material substantially impermeable with air; and a step of applying an atmosphere with at least 80% of nitrogen to the inside of the primary bag (10). In the method, the primary bag (10) is put in a secondary bag (20), and the interval between the primary bag (10) and the secondary bag (20) is set to be in a vacuum state.EP 3 199 189 A1 discloses nozzle caps formed from a rubber composition which includes a triazine, a polyethylene, a diene rubber and a chlorinated isobutylene-isoprene rubber, wherein the chlorinated isobutylene-isoprene rubber is present in a proportion of 50, 70 or 85 parts by mass, based on 100 parts by mass of a total of the rubbers in the rubber composition. EP 4 115 916 A1, which constitutes prior art under Art. 54(3) EPC, discloses medical rubber compositions comprising a triazine and a rubber component composed of a chlorinated isobutylene-isoprene rubber and a diene-based rubber, wherein 25 to 70 parts by mass of the chlorinated isobutylene-isoprene rubber are contained in 100 parts by mass of the rubber component. When a medical rubber part is sterilized by being irradiated with gamma ray, cl