JP2007050138A - Medical rubber stopper composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart excellent properties to a medical rubber stopper such as a rubber stopper or the like used in an infusion bag. <P>SOLUTION: A compound is constituted by blending 160-200 pts.mass of a softening agent and 15-40 pts.mass of polypropylene to 100 pts.mass of a styrene/ethylene/butylene/styrene block copolymer. The compound has good moldability, is easily pierced by a needle, leaks no liquid when the needle is pulled out of the rubber stopper, and has an excellent property preventing the needle piercing the rubber stopper from being easily drawn out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a medical rubber stopper composition used for, for example, an infusion bag.

  This type of rubber plug composition has good moldability, can be easily pierced with an injection needle for injecting or removing the infusion solution into the infusion bag (needle piercing property), It is required that the needle hole does not leak and the needle inserted through the rubber stopper cannot be easily removed (needle retention).

Conventionally, as a medical rubber stopper composition, a styrene-ethylene-propylene-styrene block copolymer, a polypropylene / paraffin oil having a melt index of 23 or higher, and having a hardness specified in JISK-6301 of 28 is provided. (For example, Patent Document 1).
Furthermore, a composition comprising a styrene-ethylene-propylene-styrene block copolymer, a polyolefin-based resin, and a non-aromatic rubber softener and having a hardness specified in JISK-6301 of 5 or more and less than 30 is also provided. (For example, patent document 2).

JP-A-9-601 Japanese Patent No. 7-228749

  The composition has a hardness set to less than 30 in order to ensure moldability, needle penetration and liquid leakage. However, when the hardness is 30 or less, there is a problem that the needle holding ability is deteriorated and the needle is easily removed, and the liquid leakage is not practically satisfactory.

In the present invention, as means for solving the above conventional problems, a softening agent of 160 to 200 parts by mass and polypropylene of 15 to 40 parts by mass are blended with respect to 100 parts by mass of a styrene-ethylene / butylene-styrene block copolymer. A rubber plug composition for medical use is provided.
The styrene-ethylene / butylene-styrene block copolymer has a mass average molecular weight of 300,000 to 500,000, the melt index of the polypropylene is 10 or less, and the hardness specified in JIS K 6301 of the composition is 30 to 30. 50 is desirable.

[Action]
In the present invention, since styrene-ethylene-butylene-styrene block copolymer (SEBS) is used as an elastomer, in order to ensure good needle retention, even if the hardness is 30 or more, good needle penetration and molding Sex is obtained. This is likely due to the good flexibility of the butylene block chain.
However, if the hardness exceeds 50, the elastic restoring force of the rubber plug is insufficient, and when the needle is pulled out from the rubber plug, the needle hole is not blocked and liquid leakage occurs.
When the mass average molecular weight of the SEBS is in the range of 300,000 to 500,000, the features of the SEBS are more remarkably exhibited. Polypropylene (PP) is a component that increases the hardness of the composition, but if the melt index (MI) of PP is 10 or less, the moldability is not adversely affected.

〔effect〕
When the composition of the present invention is used, the moldability, particularly injection moldability, is excellent, and the needle penetration is excellent. When the needle is removed from the rubber stopper, the needle hole is quickly closed by the elastic restoring force. There is no leakage and a rubber stopper with good needle retention is obtained.

The present invention is described in detail below.
The styrene-ethylene / butylene-styrene block copolymer (SEBS) used in the present invention preferably has a mass average molecular weight in the range of 300,000 to 500,000. When the mass average molecular weight is less than 300,000, the elastic restoring force of the rubber plug obtained is not sufficient, and there is a risk of liquid leakage when the needle is removed. However, if it exceeds 500,000, the moldability and needle stickability deteriorate.

  Examples of the softening agent used in the present invention include paraffinic oil, naphthenic oil, process oil, extender, higher fatty acid, pine oil, and the like, but considering compatibility with other components such as SEBS. Paraffinic oil is preferred.

  The softening agent is added in an amount of 160 to 200 parts by mass with respect to 100 parts by mass of the SEBS. When the addition amount of the softening agent is less than 160 parts by mass, the elastic restoring force is poor and the hardness is 50 or more, and there is a risk of liquid leakage when the needle is pulled out, and the needle sticking property is deteriorated. When the addition amount of the softening agent exceeds 200 parts by mass, the needle retaining property of the rubber stopper is deteriorated.

  The polypropylene (PP) used in the present invention preferably has a MI of 10 or less. If MI exceeds 10, problems such as deterioration of moldability and needle sticking property of the composition and risk of liquid leakage due to insufficient elastic restoring force occur.

  The amount of PP added is in the range of 15 to 40 parts by mass with respect to 100 parts by mass of SEBS. If the amount of PP added is less than 15 parts by mass, the composition will have insufficient hardness, and the needle retention of the rubber stopper will deteriorate, and if it exceeds 40 parts by mass, the moldability of the composition will deteriorate.

  In addition to the above components, fillers, pigments, dyes, antioxidants, ultraviolet absorbers and the like may be added.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
[Examples and Comparative Examples]
Using the materials shown in Table 1, pellets having the composition shown in Table 2 were prepared, and a sample having a predetermined shape was injection molded from the pellets using an injection molding machine.

<Injection conditions>
The injection molding conditions were set to a temperature of 170 to 180 ° C., an injection speed of 20%, an injection pressure of 40%, an injection holding pressure of 30%, an injection time of 10 seconds, a cooling time of 60 seconds, and a mold temperature of 40 ° C.

<Test method>
Hardness: Measured according to JIS K 6253A using a test piece having a thickness of 6 mm.
Liquid leakage / needle penetration / needle holding force: A 6 mm thick molded sample (rubber plug) obtained by the above injection molding is placed in an oven at 115 ° C. for 1 hour to perform pseudo sterilization, and then a plastic needle having a diameter of 4 mm ( Put Terumo TC-00503K) and let it stand for 4 hours. After leaving for 4 hours, attach the rubber stopper with the needle stabbed to the simulated medical infusion bag, pull out the needle with the rubber stopper attached side down, and the liquid leakage at that time, ease of needle insertion, needle holding Sex was observed. Regarding liquid leakage, the case where no liquid leaked when the needle was pulled out was accepted, and the case where the liquid leaked was rejected.
The results are shown in Table 2.

  In all the examples of the present invention, the hardness was in the range of 30 to 50, there was no liquid leakage, and both needle retention and needle penetration were good (（to ○). On the other hand, in Comparative Example 1 where the mass average molecular weight of SEBS is less than 300,000, slight liquid leakage was observed (2/10), and in Comparative Examples 2 and 3 using SEPS instead of SEBS, significant liquid leakage was observed. (7/10, 5/10), Comparative Example 4 containing paraffinic oil in excess of 200 parts by mass has poor needle retention, and Comparative Example 5 having paraffinic oil less than 160 parts by mass is 100% liquid leaking. In addition, needle stickability was not good.

The composition of the present invention provides a rubber stopper that has good moldability, needle stickability, and needle retention and does not leak, and the rubber stopper is useful for medical purposes such as for infusion bags.

Claims (2)

  A medical rubber plug composition comprising 160 to 200 parts by mass of a softening agent and 15 to 40 parts by mass of polypropylene with respect to 100 parts by mass of a styrene-ethylene / butylene-styrene block copolymer.   The styrene-ethylene / butylene-styrene block copolymer has a mass average molecular weight of 300,000 to 500,000, the melt index of the polypropylene is 10 or less, and the hardness specified in JIS K 6301 of the composition is 30 to 30. The medical rubber stopper composition according to claim 1, wherein the medical rubber stopper composition is 50.