JPH0873742A - Antibacterial silicone rubber composition - Google Patents

Abstract

PURPOSE: To obtain an antibacterial silicone rubber composition excellent in resistance to steam by incorporating a specific organopolysiloxane raw rubber, a reinforcing filler, an inorganic antibacterial agent, a cerium compound, and a curing agent. CONSTITUTION: This composition comprises the following A-E components: (A) 100 pts.wt. of an organopolysiloxane raw rubber represented by a mean unit formula Ra SiO(4-a)/2 (R is a substituted or unsubstituted monovalent hydrocarbon group; a is 1.95-2.05); (B) 10-100 pts.wt. of a reinforcing filler; (C) 0.1-5.0 pts.wt. of an inorganic antibacterial agent; (D) 0.05-5.0 pts.wt. of a cerium compound; and (E) a sufficient amount of a curing agent to cure the composition. As the inorganic antibacterial agent, silver supported on an inorganic material is particularly preferred. The inorganic material preferably includes zeolite, zirconium phosphate, calcium phosphate, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an antibacterial silicone rubber composition. More specifically, the present invention relates to an antibacterial silicone rubber composition which has excellent steam resistance and is suitably used for hoses, tubes, packings, gaskets and the like used in the presence of water, especially in the presence of high temperature steam.

[0002]

2. Description of the Related Art Silicone rubber is widely used as a tableware container, tubes for various sanitary devices, packing, and the like. In recent years, silicone rubbers having antibacterial properties have been required for these applications, and many antibacterial silicone rubber compositions have been proposed. (See JP-A-2-250499, JP-A-4-239058, and JP-A-5-1226). These antibacterial silicone rubber compositions are obtained by adding various antibacterial agents to the silicone rubber composition and enhancing their antibacterial properties.
However, these antibacterial silicone rubber compositions are inferior in hot water resistance and steam resistance, and have a fatal disadvantage that they deteriorate when used in the presence of high temperature steam and lose their properties as silicone rubber. was there.

[0003]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve the above problems, the present inventors have found that the antibacterial agents used in these antibacterial silicone rubber compositions are It has been found that the deterioration can be promoted, and that the deterioration due to steam can be remarkably suppressed by further adding a small amount of a cerium compound together with these antibacterial agents to the silicone rubber composition. I arrived. That is, an object of the present invention is to provide an antibacterial silicone rubber composition having excellent steam resistance.

[0004]

[Means for Solving the Problem and Its Action] The above-mentioned object is (A) average unit formula

Embedded image (Wherein R is a substituted or unsubstituted monovalent hydrocarbon group and a is 1.95 to 2.05) 100 parts by weight of organopolysiloxane raw rubber, (B) Reinforcing filler 10 to 100 parts by weight, (C) inorganic antibacterial agent 0.1 to 5.0 parts by weight, (D) cerium compound 0.05 to 5.0 parts by weight, (E) curing agent cure the composition of the present invention It can be achieved by an antibacterial silicone rubber composition comprising a sufficient amount of

To explain this, it is used in the present invention.
The organopolysiloxane raw rubber of the component (A) is
R is an alkyl group such as a methyl group, an ethyl group or a propyl group;
Alkenyl groups such as vinyl group and allyl group; cycloalkyl groups such as cyclohexyl group; aralkyl groups such as β-phenylethyl group; aryl groups such as phenyl group; chloromethyl group, 3-chloropropyl group, 3,3,3 A substituted or unsubstituted monovalent hydrocarbon group as exemplified by a halogenated alkyl group such as a trifluoropropyl group, and a is 1.9
It is 5 to 2.05, but one in which a is 2, that is, a diorganopolysiloxane raw rubber is preferable. The molecular weight of such a diorganopolysiloxane raw rubber is not particularly limited, and those within the range referred to in the art as organopolysiloxane raw rubber can be used, and usually 25 ° C.
Has a viscosity of 10 ⁶ centistokes or more and an average molecular weight of 25 × 10 ⁴ or more and 10 ⁶ centistokes or more,
An average molecular weight of 25 × 10 ⁴ or more, preferably 40 × 10 ⁴ or more is used.

The reinforcing filler as the component (B) has been conventionally used in silicone rubber, and examples thereof include fine silica powder such as fumed silica and precipitated silica.
Among these, silica having a particle diameter of 50 mμ or less and a specific surface area of 100 m ² / g or more is preferable. Further, there is a fine silica powder which has been surface-treated in advance with surface-treated silica, for example, organosilane, organosilazane, diorganocyclopolysiloxane, and the like, which is more preferable.

The inorganic antibacterial agent (C) used in the present invention is an essential component for imparting antibacterial properties to the composition of the present invention. Such an inorganic antibacterial agent is an inorganic ion exchanger or a porous material carrying a metal having an antibacterial effect, such as silver, copper, lead, zinc or nickel. Such inorganic antibacterial agents are commercially available and easily available. For example, as an inorganic antibacterial agent in which a metal having an antibacterial action is supported on zeolite, Zeomic [Cinenenzeomic Co., Ltd.], Bactekiller [Kanebo Co., Ltd.], Ice [Catalyst Kasei Kogyo Co., Ltd.] It is commercially available. As an inorganic antibacterial agent in which a metal having antibacterial action is carried on silica gel, it is commercially available under the trade name of Animetop [Matsushita Electric Co., Ltd.]. An inorganic antibacterial agent in which zirconium phosphate is loaded with an antibacterial metal is commercially available under the trade name of Novalon [Toagosei Co., Ltd.]. An inorganic antibacterial agent supported on calcium phosphate is commercially available under the trade name of Apacider [Sangi Co., Ltd.]. Among these, preferred are compounds selected from zeolite, zirconium phosphate and calcium phosphate, on which a metal having an antibacterial action is carried. As the metal having an antibacterial action, there are silver, copper, lead, zinc, nickel and the like, and among these, silver is particularly preferable. The compounding amount of the component (C) is in the range of 0.1 to 5.0 parts by weight. This is because antibacterial properties cannot be obtained at a blending amount of less than 0.1, and deterioration of the silicone rubber at a blending amount of more than 5.0 parts by weight may be accelerated.

The cerium compound as the component (D) functions to remarkably improve the steam resistance without lowering the antibacterial property of the composition of the present invention. Such a cerium compound is generally known as an agent for improving the heat resistance of silicone rubber,
Specific examples include cerium oxide, cerium hydroxide, cerium silanolate, and cerium octylate.
The blending amount of the component (D) is 100 parts by weight of the component (A),
It is in the range of 0.05 to 50 parts by weight. This is because when the amount is less than this, it is impossible to suppress the deterioration action of the silicone rubber by the antibacterial agent, and when the amount is more than this, only the cost is increased and no further effect can be expected.

The curing agent of component (E) used in the present invention is
It is a component for curing the composition of the present invention, and its type is not particularly limited. Typical peroxides include organic peroxides. Examples of such organic peroxides include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5 -Dimethyl-2,5-di (t-butylperoxy) 3,3,5-trimethylcyclohexane, benzoyl peroxide, 2,4 dichlorobenzoyl peroxide, 4-chlorobenzoyl peroxide and the like are exemplified. The amount of such organic peroxide added is an amount sufficient to cure the component (A), and is usually in the range of 0.1 to 15 parts by weight per 100 parts by weight of the component (A).

When the organopolysiloxane raw rubber of the component (A) has an alkenyl group represented by a vinyl group, an organohydrogen containing three or more silicon atom-bonded hydrogen atoms in one molecule. A combination of polysiloxane and platinum-based catalyst can be used as a curing agent. Examples of such an organohydrogenpolysiloxane include a trimethylsiloxy group-blocked methylhydrogenpolysiloxane having both terminals, a trimethylsiloxy group-blocked dimethylsiloxane having both terminals, and a methylhydrogensiloxane copolymer. The degree of polymerization of the organohydrogenpolysiloxane is preferably 3 to 700. The amount added is such that the ratio of the total number of moles of silicon-bonded hydrogen atoms in component (E) to the total number of moles of alkenyl groups in component (A) is (0.5: 1) to (20: 1). The amount must be such that In this case, as the platinum-based catalyst, there are chloroplatinic acid and one obtained by dissolving this in alcohol, ketone, ether, etc., a complex compound of chloroplatinic acid and olefins, platinum black and one in which platinum is supported on a carrier. used. The amount of the catalyst blended is 0.1 to 500 with respect to the total weight of the components (A) and (E) of 1 million parts by weight.
It is desirable that the amount is parts by weight. An acetylene compound, a triazole compound, a phosphine, etc. may be used as a curing retarder together with such a curing agent in order to secure working time.

The silicone rubber composition of the present invention contains, in addition to the above-mentioned components (A) to (E), various additives such as inorganic fillers, pigments and heat-resistant agents which have been conventionally used in silicone rubber compositions. You may add an agent. For example, diatomaceous earth, quartz powder, zinc oxide, magnesium oxide, titanium oxide, rouge, etc. are exemplified. The silicone rubber composition of the present invention can be easily obtained by simply uniformly mixing the above-mentioned components (A) to (E) using the mixing or kneading means used in the production of the silicone rubber composition. To be

Since the silicone rubber composition of the present invention as described above has antibacterial properties and stable steam resistance properties, it can be used especially in the presence of water, particularly in the presence of high temperature steam. Very useful for packing, gaskets, etc.

[0013]

EXAMPLES The present invention will now be described with reference to examples. In the examples, “parts” means “parts by weight”, and the viscosity is 25 ° C.
Is the value at. The steam resistance test and antibacterial test of the silicone rubber were performed by the methods described below. ○ Steam resistance test method A silicone rubber molded product (50 × 50 × 2 mm) was used as a sample, and this was placed in a steam autoclave at a temperature of 160 ° C. and a steam pressure of 6.4 Kgf / cm ² , and allowed to stand for 4 weeks. After 4 weeks, take out the silicone rubber molded product,
The physical properties were measured and reported as the rate of change of the physical property values.
Here, the physical properties of the silicone rubber molded product are JISK63.
It was measured according to the method specified in No. 01. The rate of change in physical property values was calculated according to the following equation. Change rate of physical property value = (physical properties of silicone rubber molded product after 4 weeks / weight physical properties of initial silicone rubber molded product) × 100 / physical properties of initial silicone rubber molded product ○ Antibacterial test method Silicone rubber molded product (50 × 50 × 2 mm) was used as a sample and washed with warm water and ethanol. 1 ml of the Escherichia coli bacterial solution was added dropwise thereto, and the mixture was incubated at 37 ° C. for 24 hours. Thereafter, the bacteria were washed out with a sterilized phosphate buffer solution.
The viable cell count in the washed-out test solution was measured by the pour hand plate method using a cell count measuring medium. Culture conditions: 37 ℃, 2
It was 4 hours

[0014]

Example 1 80 parts of organopolysiloxy raw rubber (polymerization degree of 5,000) consisting of 99.85 mol% of dimethylsiloxane units capped with dimethylvinylsiloxy groups at both ends and 0.15 mol% of methylvinylsiloxane units, silanol groups at both ends Organopolysiloxy raw rubber (polymerization degree of 5,000) composed of 99.45 mol% of blocked dimethylsiloxane units and 0.55 mol% of methylvinylsiloxane units 20
Parts, 8.0 parts of dimethylsiloxane blocked with silanol groups at both ends having a viscosity of 60 cSt, and 38 parts of fumed silica having a specific surface area of 200 m ² / g were charged into a kneader mixer and kneaded under heating to prepare a silicone rubber base compound. . Inorganic antibacterial agent fine powder in which silver is supported on zeolite in this compound [manufactured by Sinanen Zeomic Co., Ltd., product name Zeomic XAW10D], inorganic antibacterial agent fine powder in which silver is supported on zirconium phosphate [Toa Gosei Co., Ltd. ), Trade name Novalon AG30], and an inorganic antibacterial agent fine powder in which calcium phosphate supports silver [manufactured by Sangi Co., Ltd., trade name Apacider AW] are added in an amount of 2.0 parts each, and 0.5 part cerium oxide is added. Was compounded. Then, 0.5 part by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was added as a curing agent, and then mixed by a two-roll mill until uniform. A silicone rubber composition was obtained. The obtained silicone rubber composition was
Compression molding was carried out for 10 minutes under conditions of 0 ° C. and a pressure of 30 kgf / cm ² to obtain a sheet having a thickness of 2 mm. A steam resistance test and an antibacterial test were performed on this sheet. Table 2 shows the results.

[Table 1]

[Table 2]

[0015]

Example 2 60 parts of organopolysiloxy raw rubber (polymerization degree of 5,000) composed of 99.85 mol% of dimethylsiloxane units capped with dimethylvinylsiloxy groups at both ends and 0.15 mol% of methylvinylsiloxane units, silanol groups at both ends Organopolysiloxy raw rubber consisting of 99.45 mol% of blocked dimethylsiloxane units and 0.55 mol% of methylvinylsiloxane units (degree of polymerization: 5,000) 40
Parts, 5.0 parts of dimethylsiloxane blocked with silanol groups at both ends and having a viscosity of 60 cSt, and 33 parts of fumed silica having a specific surface area of 130 m ² / g were charged into a kneader mixer to prepare a silicone rubber compound. This compound 1
Inorganic antibacterial agent fine powder in which silver is supported on 00 parts by weight of zeolite [manufactured by Sinanen Zeomic Co., Ltd., Zeomic XAW10D], inorganic antibacterial agent fine powder in which silver is supported on zirconium phosphate [Toagosei Co., Ltd., trade name Novalon AG30], and an inorganic antibacterial agent fine powder of calcium phosphate supporting silver [manufactured by Sangi Co., Ltd., trade name Apacider AW]. 0.5 part was added and compounded. Then, 0.5 part by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was added as a curing agent, and then mixed with a two-roll mill until uniform. A silicone rubber composition was obtained. The resulting silicone rubber composition was 170
Compression molding for 10 minutes under conditions of ℃ and pressure of 30 Kgf / cm ² .
A sheet having a thickness of 2 mm was obtained. A steam resistance test and an antibacterial test were performed on this sheet. The results are shown in Table 3.

[Table 3]

[0016]

The antibacterial silicone rubber composition of the present invention comprises components (A) to (E), and particularly contains an inorganic antibacterial agent (C) and a cerium compound (D). Therefore, the silicone rubber obtained after curing is characterized by excellent antibacterial properties and steam resistance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenji Ota 2-2 Chikusaigan, Ichihara-shi, Chiba Toray Dow Corning Silicone Co., Ltd.

Claims (3)

[Claims] 1. (A) Average unit formula: (Wherein R is a substituted or unsubstituted monovalent hydrocarbon group and a is 1.95 to 2.05) 100 parts by weight of organopolysiloxane raw rubber, (B) Reinforcing filler 10 to 100 parts by weight, (C) inorganic antibacterial agent 0.1 to 5.0 parts by weight, (D) cerium compound 0.05 to 5.0 parts by weight, (E) curing agent cure the composition of the present invention An antibacterial silicone rubber composition comprising a sufficient amount of 2. The antibacterial silicone rubber composition according to claim 1, wherein the inorganic antibacterial agent as the component (B) has silver supported on an inorganic material. 3. The antibacterial silicone rubber composition according to claim 2, wherein the inorganic material is a compound selected from zeolite, zirconium phosphate and calcium phosphate.