JPH02126857A - Medical silicone rubber composition - Google Patents

Abstract

PURPOSE:To make it possible to restrain the pH fluctuations of water extracted from a molding after gamma-rays irradiation by adding specific parts by weight of magnesium carbonate or basic magnesium carbonate into a silicone rubber compound. CONSTITUTION:A medical silicone rubber compound comprises 100 parts by weight of a silicone rubber compound and 0.1-2.0 parts of at least one kind of an inorganic compound selected between magnesium carbonate and basic magnesium carbonate. Water extracted from a molding formed by the compound has small pH changes after gamma-ray irradiation and the molding consumes little amount of potassium permanganate, so that the molding is adaptable to all kinds of specifications. In this case, the goal effect of restraining the pH fluctuations of the extract water after gamma-rays irradiation may be smaller when the inorganic compounds are less than 0.1 parts by weight, while the pH fluctuations may be greater by the basicity of the inorganic compounds when more than 2.0 parts.

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention is applicable to medical silicone rubber compositions, especially in elution tests after sterilization by γ-ray irradiation, to determine pH changes, potassium permanganate consumption, etc. We manufacture a small number of medical silicone rubber molded products, parts for blood purifiers, parts for blood circuits, catheters, tubes, rubber parts used in dialyzer parts for artificial kidneys, parts for plasma separators, parts for blood filtration, pre-artificial sheets, etc. The present invention relates to a silicone rubber composition.

[Prior art] Regarding medical rubber molded products, silicone rubber molded products are widely used for internal and external use because they are non-toxic, biocompatible, and non-blood coagulant (antithrombotic). are also used for artificial organs.

These medical silicone rubber molded products are molded by processing manufacturers, sterilized with water vapor or ethylene oxide gas, and placed on the market in completely sealed packaging, but this does not include contamination due to contamination in the working environment during packaging. Furthermore, sterilization using ethylene oxide gas poses a problem with the toxicity of the remaining ethylene oxide gas.

Therefore, a method of sterilizing medical silicone rubber molded products by irradiating them with gamma rays after completely sealed packaging has been proposed, but this method also poses problems such as contamination during packaging and residual ethylene oxide gas. However, in this case, water-soluble acidic substances are generated in the molded product due to gamma ray irradiation, so the standards for dialysis-type artificial kidneys (draft) that set quality standards for this molded product and plastics for infusion fluids are not recommended. P of extracted water in dissolution tests such as container tests
A new problem is being raised where the H change becomes too large to fail the standard.

Therefore, in order to solve this problem, the formulation of the silicone rubber composition, selection of curing catalyst, post-cure conditions, etc. have been studied, and hot water washing and solvent extraction have also been tried, but there is still no perfect solution. Not discovered.

[Structure of the Invention] The present invention relates to a medical silicone rubber composition that can solve the above-mentioned problems.
) 100 parts by weight of a silicone rubber composition; 2) a small amount selected from magnesium carbonate and basic magnesium carbonate;
Both are characterized in that they each contain 0.1 to 2.0 parts by weight of one type of inorganic compound.

That is, the present inventors have studied various ways to solve the above-mentioned problems in the sterilization process of medical silicone rubber molded products that are completely sealed and packaged by γ-ray irradiation, and as a result, we have developed a method that can be used to make this molded product. When magnesium carbonate or basic magnesium carbonate is added to a silicone rubber composition, molded products made from this composition will have a small change in the pH of the extracted water even when irradiated with gamma rays, and the consumption of potassium permanganate will also be reduced. The present invention was completed by conducting research on the types and 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 any known silicone rubber composition conventionally used in molded articles of this type. Therefore, this silicone rubber composition is one that becomes a rubber-like elastic body through radical reaction crosslinking using an organic peroxide, and a curing catalyst for addition reaction curing represented by organohydrodiene polysiloxane and a platinum-based catalyst is added. It may be any of those cured by so-called addition reaction crosslinking, which is represented by the average unit formula R, 5iOi-a, where the a-depth is 1.90 to
2.05, R is bonded to an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, or a carbon atom of these Q groups. The same or different unsubstituted or substituted monovalent carbons such as chloromethyl group, 3.3.3-trifluoropropyl group, cyanomethyl group, etc. in which part or all of the hydrogen atoms are substituted with halogen atom, cyano group, etc. An organopolysiloxane in which hydrogen groups, preferably 80 mol% of which are methyl groups and 0.1 to 0.5 mol% of which are vinyl groups, preferably has a viscosity of 100 cS or more at 25°C, preferably 1000 cS. Any material based on the above may be used.

It is preferable that the terminal end of the wood organopolysiloxane is blocked with a silanol group, a methyl group, or a vinyl group, and particularly one that is blocked with a vinyl group.

This silicone rubber composition is generally made by blending the above-mentioned organopolysiloxane with a silica-based filler, and typical fillers include fumed silica, precipitated silica, quartz powder, and diatomaceous earth. For example, the particle size of these particles is preferably 50 μm or less, and the amount added is 20 to 200 parts per 10011i of organopolysilochitin. It may be within the range of i quantity parts. The composition may also contain a silane or low-molecular siloxane containing an alkoxy group, a silanol group, etc. as a silica dispersant, or an inorganic pigment for coloring.

This silicone rubber composition can be thermally cured by radical crosslinking in the presence of an organic peroxide, and examples of the organic peroxide include benzoyl peroxide, 2.4
Examples 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 an addition reaction type, in which case an organohydrodiene polysiloxane having at least two hydrogen atoms bonded to silicon atoms in the molecule and a platinum catalyst are added. is said to be the most common.

The organohydrodiene polysiloxane is exemplified by the following formula, and the amount added is = siu
/yoSi (C)I-CH2) = 0.5~5.0(
molar ratio). In addition, platinum-based catalysts that are generally added include chloroplatinic acid and complex salts of chloroplatinic acid and alcohols, ethers, aldehydes, olefins, and vinyl siloxanes, which have a What is necessary is just to add in the range of -100pp111.

On the other hand, the inorganic compound as the second component constituting the composition of the present invention is at least one selected from magnesium carbonate and basic magnesium carbonate, and these compounds include Mg(HCOa)z.

KMgH(COs)*, MgCO5, (NH4)mc
Om・MgcOs, CaCO5・MgC0z, 3M
Examples include gCO5.Mg(OH)g.3H20, among which magnesium carbonate is particularly preferred in view of the desired effect and degree of influence on silicone rubber. The amount of these added varies depending on the basicity of this compound, but if it is 0.1 part by weight or less with respect to 100 parts by weight of the silicone rubber composition as the first component, the target extracted water after γ-ray irradiation will be The effect of suppressing pH fluctuations is small (2.0 parts by weight or more may cause wide pH fluctuations due to their basicity, so this needs to be in the range of 0.1 to 2.0 parts by weight. There is.

The composition of the present invention can be obtained by uniformly mixing predetermined amounts of the first component and second component described above, and during this mixing, these may be mixed in powder form with two rolls or the like. In order to prevent poor dispersion, it is preferable to first disperse with three high-concentration rolls to create a masterbatch, and then add this masterbatch.

In order to obtain a medical silicone rubber molded article from the composition of the present invention, a curing catalyst such as the above-mentioned organic peroxide or platinum-based compound is added to the composition, and then press, injection, or transfer molding is performed according to a conventional method. , make a molded product of the desired shape using a molding method such as extrusion, and
It is cured by heating under pressure for several seconds to 10 minutes at ~400°C, and then post-cured at 150 to 200°C for 2 to 4 hours as necessary for complete curing or vulcanizing agent residual treatment. The molded product thus obtained may be cured or washed with hot water at 70 to 90°C.The molded product thus obtained may be heat-sealed using a known method such as olefin plastic film, polyimide amide film, cellulose film, etc. The product is completely sealed and packaged and then sterilized with gamma ray irradiation, but the dose of gamma rays is 2 to 8.
Mrad may be used, and molded products made from the composition of the present invention will fail various tests because the pH change of the extracted water is small even by this γ-ray irradiation, and the amount of potassium permanganate consumed is small. The advantage is that there are far fewer problems.

Next, examples of the present invention will be given, in which parts are parts by weight, and viscosity is a value measured at 25°C.

Example 1 The molecular chain terminal is (C)Iz-Ct() (CH3) 2s
ioo, s-blocked (C)I3)zsio 1-position 99.8 mol%, (CHs) (C)lx-CH)S
To 100 parts of organopolysiloxane raw rubber containing 0.2 mol% of iO, (CHs)ssio was added. , 40 parts of fumed silica with a specific surface area of 230 m2/g and 1.0 part of formula siloxane whose molecular chain ends are capped with silanol groups were added, and the mixture was heated at 180°C/2 in a kneader.
A silicone rubber composition A was prepared by heat treatment for a period of time.

Next, magnesium carbonate and basic magnesium carbonate compounds shown in Table 1 were added to 100 parts of this composition A in the amounts shown in Table 1, and vulcanizing agent C-8^ [Shin-Etsu Chemical Co., Ltd. 80% paste of 2,5-bis(t-butylperoxy)-2,5-dimethylhexane] was added, and this was press-vulcanized at 170°C for 10 minutes to form a 2a+m sheet. After post-curing at 200°C for 4 hours, this sheet was irradiated with γ-rays at 3 Mrad or 6 Mrad, and the pH of the extract was changed according to the elution test method of the dialysis type artificial kidney device standard test. When the amount of potassium permanganate consumed was measured, the results shown in Table 1 were obtained.

Example 2 A sheet was made in the same manner as in Example 1 from a composition obtained by changing the amount of magnesium carbonate used in Example 1 as shown in Table 2, and this sheet was irradiated with gamma rays. pH change of the extract after, potassium permanganate quenching
When tffi was examined, the results shown in Table 2 were obtained.

Example 3 90 parts of dimethylpolysiloxane having a viscosity of 5.000 cS and whose molecular terminal end was capped with a dimethylvinylsilyl group were added with Sin units, (CH3)5siOo, s units, (
GHz-CH) (CII3), 5iO(,, consists of 5 units, 5i02/ (CH3) 5sioo, s+
(CL・C)l) (C)Ia)zsiOo, s=
1.0 (molar ratio) and a vinyl group content of 1% by weight 10 parts of a siloxane copolymer, 30 parts of fumed silica used in Example 1, methylhydrodiene polysiloxane F99 [parts manufactured by Shin-Etsu Chemical Co., Ltd.] name] 1.5
Part of chloroplatinic acid in 2-ethylhexanol solution (platinum gold ff 12%) O, OS part and the amount of MgC shown in Table 3 was added to this to form a silicone rubber composition B.
When O5 was added and mixed uniformly, the same test as in Example 1 was conducted on this composition, and the results shown in Table 3 were obtained.

Table Example 4 Commercially available silicone rubber compound for medical use K
E153U, KE1551U, KE951U, K
When the same test as in Example 1 was conducted on a composition obtained by adding MgCO3 in the amount shown in Table 4 to E1920A, B (liquid rubber) [both parts names manufactured by Shin-Etsu Chemical Co., Ltd.], the same test as in Example 1 was conducted. The results shown in Table 4 were obtained.

Claims (1)

[Claims] 1.1) 100 parts by weight of a silicone rubber composition 2) 0.1 to 2.0 parts by weight of at least one inorganic compound selected from magnesium carbonate and basic magnesium carbonate A medical silicone rubber composition.