JPH0622588B2 - Medical silicone rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a medical silicone rubber composition, particularly a small pH change and potassium permanganate consumption even in a dissolution test after sterilization treatment by γ-ray irradiation. Silicone that gives rubber parts used for medical silicone rubber moldings, blood purifier parts, blood circuit parts, catheters, and cheap, such as artificial kidney dialyzer parts, plasma separator parts, blood filter parts, artificial stomach sheets, etc. The present invention relates to a rubber composition.

[Prior Art] Silicone rubber molded products are widely used for internal and external use because they are excellent in non-toxicity, biocompatibility and non-coagulability (anti-thrombogenicity) for medical rubber molded products. Is also used for artificial organs.

This medical silicone rubber molded product is molded by a processing manufacturer, then sterilized with steam, ethylene oxide gas, etc., and put on the market in a completely hermetically sealed package. Moreover, sterilization with ethylene oxide gas has a problem in the toxicity of the remaining ethylene oxide gas.

Therefore, for this medical silicone rubber molded product, a method of sterilizing by γ-ray irradiation after completely sealed packaging has been proposed, which also causes problems such as contamination during packaging and residual ethylene oxide gas. However, in this case, since water-soluble acidic substances are generated in the molded product by γ-ray irradiation, the dialysis-type artificial kidney standard (draft) and the infusion plastic that set the quality standard for this molded product. PH of extracted water in dissolution tests such as container tests
A new problem has been raised that the change is so large that it fails the standard.

Therefore, in order to solve this problem, blending of a silicone rubber composition, selection of a curing catalyst, post-curing conditions, and the like have been studied, and attempts have been made to use hot water washing, solvent extraction, etc. Not found.

[Structure of the Invention] The present invention relates to a medical-use silicone rubber composition capable of solving such problems, which is 1) 100 parts by weight of the silicone rubber composition, 2) magnesium carbonate, and basic carbonate. It is characterized by comprising 0.1 to 2.0 parts by weight of at least one inorganic compound selected from magnesium.

That is, the present inventors have conducted various studies on methods for solving the above-mentioned problems in the sterilization treatment of γ-ray irradiation of medical silicone rubber molded articles that have been completely hermetically packaged, and as a result, they have been used for making these molded articles. When magnesium carbonate or basic magnesium carbonate is added to the silicone rubber composition, the molded product made from this composition has a small pH change in its extracted water even when it is irradiated with γ-rays, and also consumes potassium permanganate. It was found that the amount would decrease, and the present invention was completed by conducting research on the types and blending amounts of magnesium carbonate and basic magnesium carbonate.

The silicone rubber composition as the first component constituting the composition of the present invention may be a known one which has been conventionally used for this type of molded article. Therefore, as the silicone rubber composition, a rubber-like elastic body is obtained by radical reaction cross-linking with an organic peroxide, an organohydrogen polysiloxane and a curing catalyst for addition reaction curing represented by a platinum-based catalyst are added. It may be any of those which are cured by so-called addition reaction cross-linking. In the formula, a = 1.90 to 2.05, R is an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an alkenyl group such as a vinyl group and an allyl group, an aryl group such as a phenyl group and a tolyl group, or Same or different species such as chloromethyl group, 3,3,3-trifluoropropyl group, cyanomethyl group, etc. in which some or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atom, cyano group, etc. An unsubstituted or substituted monovalent hydrocarbon group, preferably 80 mol% of which is a methyl group and 0.1 to 0.5 mol% of which is a vinyl group, an organopolysiloxane, preferably at 25 ° C.
The viscosity may be 100 cS or more, preferably 1000 cS or more.

It is desirable that the terminal of the present organopolysiloxane is capped with a silanol group, a methyl group, or a vinyl group, and particularly, a terminal capped with a vinyl group.

This silicone rubber composition is generally a mixture of the above-mentioned organopolysiloxane with a silica-based filler, and as the filler, famed silica, precipitated silica, quartz powder, diatomaceous earth, etc. are typical. However, it is preferable that these particles have a particle size of 50 μm or less.
The range may be 20 to 200 parts by weight with respect to 100 parts by weight. In addition, this composition is a silane or a low-molecular-weight siloxane containing an alkoxy group, a silanol group, or the like as a silica dispersant,
Further, it may include an inorganic pigment for coloring.

This silicone rubber composition can be heat-cured by radical crosslinking in the presence of an organic peroxide, and as the organic peroxide, benzoyl peroxide, 2,4-
Examples thereof include dichlorobenzoyl peroxide, orthochlorobenzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, and 2,5-bis (t-butylperoxy) -2,5-dimethylhexane.

However, this silicone rubber composition may be of addition reaction type. In this case, it is necessary to add an organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms in the molecule and a platinum catalyst. Is the most common. This organohydrogenpolysiloxane has the following formula The amount added is ≡SiH / based on the amount of vinyl groups in the above-mentioned organopolysiloxane.
≡Si (CH = CH ₂ ) = 0.5 to 5.0 (molar ratio) may be provided. As the platinum-based catalyst added here, chloroplatinic acid, chloroplatinic acid and a complex salt of alcohol, ether, aldehyde, olefin, vinylsiloxane, etc. are generally used.
It may be added in the range of up to 100 ppm.

On the other hand, the inorganic compound as the second component which constitutes the composition of the present invention is at least one selected from magnesium carbonate and basic magnesium carbonate. For these compounds, Mg (HCO ₃ ) ₂ , KMgH _{(CO 3) 2, MgCO 3} , (NH 4) 2
CO ₃ · MgCO ₃ , CaCO ₃ · MgCO ₃ , 3MgCO ₃ · Mg (OH) ₂ · 3H ₂ O, etc. are exemplified, but magnesium carbonate is particularly preferable among them due to the intended effect and the effect on silicone rubber. It is suitable. The addition amount of these varies depending on the basicity of the compound, but if the amount is 0.1 parts by weight or less relative to 100 parts by weight of the above-mentioned silicone rubber composition as the first component, the pH of the target extraction water after γ-irradiation is The fluctuation suppressing effect is small, and if it is 2.0 parts by weight or more, the basicity thereof may cause a large pH fluctuation. Therefore, it is necessary to set it in the range of 0.1 to 2.0 parts by weight.

The composition of the present invention is obtained by uniformly mixing the predetermined amounts of the above-mentioned first component and second component, and at the time of this mixing, these may be kneaded in powder form by a two-roll mill or the like. However, in order to prevent poor dispersion, it is preferable to first disperse with a high-concentration three-roll to form a masterbatch, and add this.

To obtain a medical-use silicone rubber molded article from the composition of the present invention, a curing catalyst such as the above-mentioned organic peroxide or platinum compound is added to this composition, and then press, injection, transfer mold are carried out according to a conventional method. , Make a molded product of the desired shape by a molding method such as extrusion, 120 ~ 4
Heat at 00 ℃ for a few seconds to 10 minutes under pressure as necessary to cure, then post cure at 150-200 ℃ for 2-4 hours as necessary for complete curing and treatment of vulcanizing agent residue. Alternatively, it may be washed with hot water at 70 to 90 ° C. The thus obtained molded article is completely sealed and packaged by a known method, for example, olefin plastic film, polyimideamide film, and cellulose film by heat sealing, and then sterilized by γ-ray irradiation to obtain a product. The irradiation dose of this γ-ray may be set to 2 to 8 Mrad, and the molded article made from the composition of the present invention has a small pH change in the extracted water even by the γ-ray irradiation and consumes potassium permanganate. The small number provides the advantage that very few failures of the various tests are possible.

Next, examples of the present invention will be given. Parts in the examples are parts by weight, and viscosities are measured values at 25 ° C.

Example 1 molecular chain terminals (CH ₂ = CH) blocked with _{(CH 3) 2 SiO 0.5 (} CH 3) 2
To 100 parts of organopolysiloxane raw rubber consisting of 99.8 mol% of SiO unit and 0.2 mol% of (CH ₃ ) (CH ₂ = CH) SiO unit, (CH ₃ ) ₃ S
Fumed silica with a specific surface area of 230 m ² / g treated with _0.5 units of iO 40 minutes, a formula in which the molecular chain ends are blocked with silanol groups Then, 1.0 part of dimethylpolysiloxane represented by the formula (1) was added, and heat treatment was performed at 180 ° C. for 2 hours in a kneader to prepare a silicone rubber composition A.

Next, to 100 parts of this composition A, the magnesium carbonate and basic magnesium carbonate compounds shown in Table 1 were added in the amounts shown in Table 1, and the vulcanizing agent C-8A [Shin-Etsu Chemical Co., Ltd.
Brand name: 2,5-bis (t-butylperoxy)-
2,5-dimethylhexane 80% paste] was added, and this was press-vulcanized at 170 ° C for 10 minutes to give a 2 mm sheet, which was post-cured at 200 ° C / 4 hours. Was irradiated with 3 Mrad or 6 Mrad of γ-ray, and the pH change and potassium permanganate consumption of the extract were measured according to the elution test method of the dialysis type artificial kidney device standard test for this sheet. The exact result was obtained.

Example 2 A sheet was made in the same manner as in Example 1 from the composition obtained by changing the addition amount of magnesium carbonate used in Example 1 as shown in Table 2, and the sheet was irradiated with γ rays. When the pH change and the potassium permanganate consumption of the subsequent extract were examined, the results shown in Table 2 were obtained.

Example 3 90 parts of dimethylpolysiloxane having a molecular chain end blocked with a dimethylvinylsilyl group and having a viscosity of 5,000 cS, SiO ₂ unit, (CH ₃ ) ₃ SiO _0.5 unit, (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit, SiO ₂ / (CH ₃ ) ₃ SiO _0.5 + (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 = 1.0
10 parts of siloxane copolymer having a vinyl group content of 1% by weight (molar ratio), fumed silica used in Example 1
30 parts of methylhydrogen polysiloxane / KF99 [trade name of Shin-Etsu Chemical Co., Ltd.] was added to prepare a silicone rubber composition B, and then a solution of chloroplatinic acid in 2-ethylhexanol (platinum content) was added. 2%) 0.05 parts and the amount of MgCO ₃ shown in Table ₃ were added and mixed uniformly, and the same test as in Example 1 was conducted on this composition.
The results as shown in the table were obtained.

Example 4 Commercially available medical silicone rubber compound KE
The composition obtained by adding 153U, KE1551U, KE951U, KE1920A, B (liquid rubber) [all are trade names manufactured by Shin-Etsu Chemical Co., Ltd.] to the amounts of MgCO ₃ shown in Table 4 was used. When the same test was performed, the results as shown in Table 4 were obtained.

Claims (1)

[Claims] 1. A medical silicone rubber composition comprising 1) 100 parts by weight of a silicone rubber composition and 2) 0.1 to 2.0 parts by weight of at least one inorganic compound selected from magnesium carbonate and basic magnesium carbonate. object.