JP2013043957A - Rubber composition for needle cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition that makes a cap usable for both γ-ray sterilization and EOG sterilization having entirely different required characteristics.SOLUTION: The rubber composition for a needle cap protects a needle mounted on a tip of glass syringe comprising 70-100 mass% of ethylene propylene diene rubber in a base polymer. Preferably the amount of the ethylene propylene diene rubber is 100 mass% in the base polymer.

Description

The present invention relates to a rubber composition for producing a needle cap such as a syringe.

Conventionally, a medical instrument such as a syringe is delivered to a medical institution or the like after being subjected to some sterilization process including steam sterilization. As the sterilization treatment, for example, γ-ray sterilization, electron beam sterilization, EOG (engineered oxide gas) sterilization, etc. are known in addition to high-pressure steam sterilization. In recent years, γ-ray sterilization treatment and EOG sterilization treatment, which are sterilization under extremely severe conditions as compared with high-pressure steam sterilization, are increasing. These γ-ray sterilization and EOG sterilization processes are sterilized with the needle cap attached to the needle portion of the syringe.

Patent Document 1 proposes a syringe damage prevention cap made of a rubber material such as natural rubber, butyl rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, or silicon rubber. However, in the EOG sterilization process, if highly air permeable isoprene rubber (IR) or butadiene rubber (BR) is used to reliably remove highly toxic EOG gas after sterilization, unsaturated bonds are formed in the molecular structure. On the contrary, there is a problem that the rubber deteriorates when irradiated with radiation during γ-ray sterilization. On the other hand, in γ-ray sterilization treatment, the use of butyl rubber (IIR), which has few sterilized unsaturated bonds and is not easily attacked by radiant-strength electrons, has the property of preventing air from escaping. Therefore, there is a problem that the permeability of the highly toxic EOG gas is poor and the EOG gas cannot be sufficiently removed.

JP 2007-125205 A

It is an object of the present invention to provide a rubber composition used for a needle cap of a syringe that can be used for γ-ray sterilization and EOG sterilization processes having completely different required properties.

That is, the present invention relates to a rubber composition for a needle cap that protects a needle attached to the tip of a syringe barrel in which 70 to 100% by mass of the base polymer is ethylene propylene diene rubber.

It is preferable that 100% by mass in the base polymer is ethylene propylene diene rubber.

In the present invention, by using ethylene propylene diene rubber, in the needle cap that protects the needle attached to the tip of the syringe barrel that is exposed under special conditions, both γ-ray resistance and gas permeability are compatible. And can be suitably used for γ-ray sterilization and EOG sterilization treatment.

It is sectional drawing (a) and a general view (b) of a needle cap.

In the rubber composition for a needle cap of the present invention, 70 to 100% by mass in the base polymer is ethylene propylene diene rubber (EPDM). The lower limit of the EPDM content in the base polymer is 70% by mass, preferably 80% by mass, and more preferably 100% by mass. If it is less than 70% by mass, the rubber tends to be significantly deteriorated when irradiated with radiation during γ-ray sterilization.

The needle cap is sterilized together in a state where it is incorporated in a certain part of a medical device such as a syringe. Particularly in the case of γ-ray sterilization treatment, the rubber product itself often deteriorates at the same time as sterilization. If the rubber deteriorates, depending on the rubber material, the “eluate test” of the “Japanese pharmacopoeia infusion solution rubber stopper test method” may fail. On the other hand, in the case of EOG sterilization treatment, for example, the needle attached to the tip of the syringe barrel is sterilized with a rubber product called “needle cap = needle cap”. In order to sterilize the tip, the EOG gas needs to pass through the “needle cap” and reach the inside. Further, since EOG gas is extremely toxic and highly reactive, there is a possibility that the drug may be denatured and deactivated if the gas remains, so that it is necessary to quickly remove the gas from the syringe after sterilization is completed. From such a viewpoint, in the present invention, ethylene propylene diene rubber having high gas permeability and small deterioration due to γ rays is used.

The rubber composition for needle caps of the present invention contains a crosslinking agent. Examples of the crosslinking agent include peroxide-based crosslinking agents. Examples of the peroxide-based crosslinking agent include tertiary butyl peroxide and dicumyl peroxide. 1.0-3.0 mass parts is preferable with respect to 100 mass parts of base polymer, and, as for the compounding quantity of a crosslinking agent, 1.5-2.5 mass parts is more preferable. If the amount is less than 1.0 part by mass, the amount of crosslinking tends to decrease and the strength of the needle cap product tends to be weakened. The amount of elution tends to increase.

The rubber composition for needle caps of this invention can mix | blend the additive generally used for manufacture of a rubber composition other than a base polymer. For example, reinforcing fillers, anti-aging agents, softening agents such as oil, zinc oxide, stearic acid, wax, vulcanization accelerators, processing aids and the like can be appropriately blended.

Examples of the reinforcing filler include silica, carbon black, talc, calcined clay, titanium oxide and the like, and talc, calcined clay, magnesium oxide, titanium oxide and the like are particularly preferable. 1-100 mass parts is preferable with respect to 100 mass parts of base polymers, and, as for the compounding quantity of a filler, 3-40 mass parts is more preferable.

The needle cap is attached to the needle base at the tip of the syringe barrel as shown in FIG. 1 to protect the injection needle existing in the needle base, and the material is usually plastic or rubber. When EOG gas sterilization is often employed, rubber with high gas permeability is often used. 1A is a cross-sectional view, and FIG. 1B is an overall view. As can be seen from the cross-sectional view, a cavity for an injection needle is formed at the center. As what is sterilized in the state which put the needle | hook cap on the syringe, a prefilled syringe is mentioned, for example. In some cases, a needle case is mounted on the needle cap.

The γ-ray sterilization treatment is a treatment for sterilizing a final product by irradiating the product with γ-rays. The irradiation dose of γ rays is preferably 25 to 40 kGy, and more preferably 30 to 40 kGy. If it is less than 25 kGy, the sterilization process becomes insufficient, and if it exceeds 40 kGy, the needle cap rubber tends to be greatly deteriorated.

EOG sterilization is a method of sterilizing equipment in an atmosphere of ethylene oxide gas. The concentration of the ethylene oxide gas is preferably 450 to 550 mmg / l, and more preferably 450 to 500 mmg / l. If it exceeds 550 mmg / l, the residual concentration of EOG gas tends to increase after sterilization.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Below, various chemical | medical agents used by the Example and the comparative example are demonstrated.
Isoprene rubber: Nippon IR2200GA manufactured by ZEON CORPORATION
Butyl rubber: HT-1066 manufactured by Nippon Butyl Co., Ltd.
Ethylene propylene diene rubber: EPT9090M manufactured by Mitsui Chemicals, Inc.
Magnesium oxide: Kyomag MF150 manufactured by Kyowa Chemical Industry Co., Ltd.
Titanium oxide: Type A100 manufactured by Ishihara Sangyo Co., Ltd.
Anti-aging agent: Sognox 1076PW manufactured by Kyodo Yakuhin Co., Ltd.
Baked clay: Satinton W manufactured by BASF Catalysts LLC
Talc: Mistron CB manufactured by Luzenuc America / Rio Tinto Minerals
Tertiary butyl peroxide: Perbutyl L manufactured by NOF Corporation
Sulfur-based crosslinking agent: Disnet DB manufactured by Sankyo Kasei Co., Ltd.

Examples 1-2 and Comparative Examples 1-2
According to the blending ratio shown in Table 1, the mixture was kneaded with a closed kneader or an open roll to obtain an unvulcanized rubber blend. The unvulcanized rubber compound was crosslinked by pressurizing and heating at 155 ° C. using a predetermined molding die to obtain the following two types of molded vulcanized products.
(1) Gas permeation test sample thickness of about 1.0 mm, 110 mm × 240 mm vulcanized slab sheet (2) A molding die having the shape of a sample “needle cap” for elution test before and after γ-ray irradiation was used. Molded vulcanized product

The following evaluation was performed using the obtained molded vulcanized product. The evaluation results are shown in Tables 2 and 3.

Sample Evaluation Method (1) Gas Permeability Test A permeability test was conducted according to JIS K7126 using a vulcanized slab sheet having a thickness of about 1.0 mm and 110 mm × 240 mm.
Two types of oxygen permeability and air permeability were calculated. The larger the number, the higher the gas permeability.

(2) Elution test before and after γ-irradiation “needle cap” shaped samples were irradiated with 40 kGy of γ-ray, and both irradiated and unirradiated samples were subjected to the Japanese Pharmacopoeia “Rubber stopper test method for infusion solutions. Was carried out.

The rubber composition of Comparative Example 1 in which the base polymer is isoprene rubber (IR) has a high gas permeability and is excellent in gas permeability. Therefore, it is a rubber material compatible with EOG gas sterilization. However, as can be seen from the results of the eluate test, γ-ray sterilization cannot be performed because “KMnO ₄ reducing substance” in the eluate test is rejected when γ-rays are irradiated.

In addition, in the rubber composition of Comparative Example 2 in which the base polymer is butyl rubber (IIR), the eluate test is passed and excellent in γ-ray resistance even after γ-ray irradiation. However, it cannot be used for EOG gas sterilization because its gas permeability is very low and it is difficult for gas to pass through.

On the other hand, in the rubber compositions of Examples 1 and 2, the gas permeability is slightly lower than that of the isoprene rubber (IR) of Comparative Example 1, but the gas permeability is much higher than that of the butyl rubber of Comparative Example 2, and EOG. It can also be used for gas sterilization. Moreover, even after irradiating γ-rays, each item of the eluate test can be used for γ-ray sterilization without any problem.

Claims (2)

A rubber composition for a needle cap which protects a needle attached to the tip of a syringe barrel in which 70 to 100% by mass of the base polymer is ethylene propylene diene rubber. The rubber composition for a needle cap according to claim 1, wherein 100% by mass in the base polymer is ethylene propylene diene rubber.

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