JPS6351705B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention also applies to medical silicone rubber compositions, especially in elution tests after sterilization by γ-ray irradiation.
Medical silicone rubber molded products with low pH changes and potassium permanganate consumption, parts for blood purifiers,
The present invention relates to a silicone rubber composition that provides rubber parts for use in blood circuit parts, catheters, tubes, such as dialyzer parts for artificial kidneys, plasma separator parts, blood filtration parts, artificial stomach sheets, and the like. (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 have excellent non-blood coagulation properties (antithrombotic properties). are also used for artificial organs. This medical silicone rubber molded product is molded by a processing manufacturer, then sterilized using water vapor, ethylene oxide gas, etc., and placed on the market in completely sealed 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 γ
Because water-soluble acidic substances are generated in molded products due to radiation irradiation, they are extracted during elution tests such as the dialysis-type artificial kidney standards (draft) that establish quality standards for these molded products and tests on plastic containers for infusions. A new problem has been raised in which the PH change in water becomes large enough to cause it to fail the standard. Therefore, in order to solve this problem, the formulation of the silicone rubber composition, selection of curing solvent, post-cure conditions, etc. have been studied, and attempts have been made to use hot water washing and solvent extraction, but there is still no complete solution. No countermeasures have been found. (Structure of the Invention) The present invention relates to a medical silicone rubber composition that can solve these problems, and includes: 1) 100 parts by weight of a silicone rubber composition; 2) oxides of calcium and magnesium; 0.1 to 2.0 parts by weight of at least one inorganic compound selected from hydroxides, hydroxides, and carbonates. 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 oxides, hydroxides, and carbonates of calcium and magnesium are added to a silicone rubber composition, molded products made from this composition exhibit a small PH change in the extracted water even when irradiated with gamma rays. They discovered that the amount of potassium manganate consumed was also reduced, and conducted research on the types and amounts of calcium and magnesium compounds, and completed the present invention. 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 can be made into a rubber-like elastic body by radical reaction crosslinking with an organic peroxide, or a curing catalyst for addition reaction curing, such as organohydrodiene polysiloxane and a platinum-based catalyst. The average unit formula is

[Formula], where a = 1.90 to 2.05, R is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkenyl group such as a vinyl group or an allyl group, a phenyl group, a tolyl group, etc. Chloromethyl groups in which part or all of the hydrogen atoms bonded to the carbon atoms of aryl groups or these groups are substituted with halogen atoms, cyano groups, etc.
Same or different unsubstituted or substituted monovalent hydrocarbon groups, such as 3,3,3-trifluoropropyl group, cyanomethyl group, etc., preferably 80 mol% of which is a methyl group, and 0.1 to 0.5 mol% of which is a methyl group. An organopolysiloxane having a vinyl group, preferably
Any material may be used as long as it has a viscosity of 100 cS or more, preferably 1000 cS or more at 25°C. Note that the terminals of the present organopolysiloxane are preferably capped with silanol groups, methyl groups, or vinyl groups, particularly those capped with vinyl groups. 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, these particles preferably have a particle size of 50 μm or less, and the amount added may range from 20 to 200 parts by weight per 100 parts by weight of the organopolysiloxane.
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 composition can be heat-cured by radical crosslinking in the presence of an organic peroxide, and examples of the organic peroxide include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, orthochlorobenzoyl peroxide,
Examples include 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.
This organohydrodiene polysiloxane has the following formula:

【formula】 【formula】

For example, the amount of addition is ≡SiH/≡Si (CH=CH ₂ )=0.5 to 5.0 (molar ratio) with respect to the amount of vinyl groups in the organoporsiloxane described above.
It is sufficient to set the range to give . In addition, platinum-based catalysts that are commonly added include chloroplatinic acid and complex salts of chloroplatinic acid and alcohols, ethers, aldehydes, olefins, and vinyl siloxanes, which are suitable for this silicone rubber composition. 1~
It may be added within a range of 100ppm. On the other hand, the inorganic compound as the second component constituting the composition of the present invention is at least one selected from oxides, hydroxides, and carbonates of calcium and magnesium, and these compounds include CaO, Ca(OH) ₂ , _CaCO3 , Ca( _HCO3 ) ₂ ,
MgO, Mg(OH) ₂ , _MgCO3 , _3MgCO3・Mg
(OH) _{2.3H 2} O and the like are exemplified, but among these, carbonates are 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 less than 0.1 part by weight based on 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, and if the amount exceeds 2.0 parts by weight, there is a risk that PH fluctuations will become large due to their basicity. The composition of the present invention is obtained by uniformly mixing predetermined amounts of the above-described first component and second component,
For this mixing, these powders may be kneaded using two rolls, but in order to prevent poor dispersion, first disperse them using three rolls at a high concentration to create a masterbatch, and then add this. It is better to 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 compound is added to the composition, and then the composition is pressed, injected, etc. in a conventional manner. A molded product in the desired shape is made using a molding method such as transfer molding or extrusion, and is heated at 120 to 400°C for a few seconds to 10 minutes under pressure if necessary to cure it, and then completely cured and removes the vulcanizing agent residue. For treatment, post-curing may be performed at 150 to 200°C for 2 to 4 hours, or hot water washing may be performed at 70 to 90°C, if necessary. The molded product thus obtained can be manufactured using known methods such as olefin plastic film,
Completely sealed and packaged with heat sealing of polyimide amide film, cellulose film, etc.
The product is then sterilized by γ-ray irradiation, but the dose of γ-ray irradiation may be between 2 and 8 Mrad, and molded products made from the composition of the present invention can be sterilized by γ-ray irradiation.
Even when irradiated with radiation, the pH change of the extracted water is small.
The low consumption of potassium permanganate also provides the advantage of significantly fewer failures in various tests. Next, examples of the present invention will be given, in which parts are by weight, and viscosity is a value measured at 25°C. Example 1 Molecular chain ends were blocked with (CH ₂ =CH) (CH ₃ ) ₂ SiO _0.5 (CH ₃ ) ₂ SiO units 99.8 mol%, (CH ₃ )
100 parts of organoporsiloxane raw rubber consisting of 0.2 mol% of (CH ₂ =CH) SiO units, 40 parts of fumed silica with a specific surface area of 230 m ² /g surface-treated with _0.5 units of (CH ₃ ) ₃ SiO, and molecular chain terminals Formulas capped with silanol groups

A silicone rubber composition A was prepared by adding 1.0 part of dimethylpolysiloxane represented by the formula and heat-treating the mixture in a kneader at 180°C for 2 hours. Next, the calcium and magnesium 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-8A [trade name, 2, manufactured by Shin-Etsu Chemical Co., Ltd. , 80% paste of 5-bis(t-butylperoxy)-2,5-dimethylhexane] was press-cured at 170°C for 10 minutes to form a 2 mm sheet, and then vulcanized at 200°C/ After 4 hours of post cure, this sheet
After 3Mrad or 6Mrad of γ-ray irradiation, we measured the PH change of the extract and the amount of potassium permanganate consumed on this sheet according to the elution test method of the dialysis type artificial kidney device standard test, and the results are also listed in Table 1. The results were as expected.

[Table] 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. PH change of extract after γ-ray irradiation,
When we looked at the amount of potassium permanganate consumed, we found that
The results shown in Table 2 were obtained.

【table】

[Table] Example 3 Dimethylpolysiloxane with a viscosity of 5000 cS, whose molecular chain terminals are capped with dimethylvinylsilyl groups
90 parts, SiO ₂ unit, (CH ₃ ) ₃ SiO _0.5 unit, (CH ₂ =
CH) (CH ₃ ) ₂ Consists of _0.5 units of SiO ₂ /
(CH ₃ ) ₃ SiO _0.5 + (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 = 1.0
10 parts of a siloxane copolymer with a vinyl group content of 1% by weight (molar ratio), 30 parts of the surface-treated fumed silica used in Example 1, methylhydrodiene polysiloxane KF99 [product manufactured by Shin-Etsu Chemical Co., Ltd.] Silicone rubber composition B was prepared by adding 1.5 parts of chloroplatinic acid in 2-ethylhexanol (platinum content 2%) and 0.05 parts of chloroplatinic acid in 2-ethylhexanol (platinum content 2%) and the amounts of CaCO ₃ and MgCO ₃ shown in Table 3. When this composition was subjected to the same test as in Example 1, the results shown in Table 3 were obtained.

[Table] Example 4 Commercially available medical silicone rubber compounds: KE153U, KE1551U, KE951U,
The same test as in Example 1 was conducted on compositions obtained by adding MgCO ₃ in the amount shown in Table 4 to KE1920A, B (liquid rubber) [both trade names manufactured by Shin-Etsu Chemical Co., Ltd.]. As a result, the results shown in Table 4 were obtained.

【table】

【table】

Claims (1)

[Claims] 1 1 Silicone rubber composition 100 parts by weight 2 At least one inorganic compound selected from oxides, hydroxides, and carbonates of calcium and magnesium 0.1 to 2.0 parts by weight Medical silicone rubber composition. 2. The medical silicone rubber composition according to claim 1, wherein the inorganic compound is selected from magnesium oxide, magnesium carbonate, and basic magnesium carbonate. 3. The medical silicone rubber composition according to claim 1, wherein the inorganic compound is calcium hydroxide or calcium carbonate.