JP2007031652A - Mildewproof silicone rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone rubber composition exhibiting excellent mildewproof properties capable of sufficiently corresponding to present fungi which are allowed to have resistance. <P>SOLUTION: The silicone rubber composition is obtained by compounding 0.01-10 pts.wt. imazalil based on 100 pts.wt. silicone rubber base polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicone rubber composition having excellent antifungal properties.

Giving anti-fungal and antibacterial properties to silicone rubber compositions has been practiced for a long time, and as a method there is usually a combination of anti-fungal and anti-bacterial agents, and as such agents, imidazole as an organic system Are known, such as a silver-substituted zeolite, as shown in Patent Document 1, and many of them use an antibacterial action of silver ions. Patent Document 2 proposes that benzimidazolyl carbamate and bis (2-pyridiothio-1-oxide) zinc be used together, and Patent Document 3 proposes that a mordenite group and hinokitiol are used in combination.
Japanese Patent Laid-Open No. 7-62242 JP-A-6-40821 JP 2002-363413 A

  According to the above-described conventional technology, although a certain fungicidal property is exhibited, it is difficult to say that the effect is sufficiently satisfactory, and it has not been able to sufficiently cope with the current mold that has been resistant. In particular, in the case of a one-component room temperature curable polyorganosiloxane composition containing a ketoxime group-containing organosilane and / or a partially hydrolyzed condensate thereof, it has an antifungal property under high humidity such as in a bathroom or kitchen. It was insufficient.

  As a result of intensive studies to obtain a silicone rubber composition having excellent antifungal properties, the present inventor has found that imazalil exhibits excellent antifungal properties in silicone rubber, and has completed the present invention.

  That is, the present invention is a mold-proof silicone rubber composition characterized by blending 0.01 to 10 parts by weight of imazalil with respect to 100 parts by weight of a silicone rubber base polymer.

  Hereinafter, the present invention will be described in detail. First, the silicone rubber composition in the present invention becomes a rubber elastic body by being cured at room temperature or by heating, etc., and (a) a silicone rubber base polymer, (b) a curing agent, and various kinds as necessary. An additive and the like are uniformly dispersed. Among the various components used in such a composition, (a) the silicone rubber base polymer and (b) the curing agent are appropriately selected according to the reaction mechanism for obtaining the rubber elastic body. As the reaction mechanism, (1) a crosslinking method using an organic peroxide vulcanizing agent, (2) a method using a condensation reaction, (3) a method using an addition reaction, and the like are known. It is well known that the preferred combination of component and component (b), ie a curing catalyst or crosslinker, is determined. In addition, when chemically explaining silicone rubber,

Is formed as a chain polymer. Since this unit is called organosiloxane, the silicone rubber base polymer can be chemically expressed as polyorganosiloxane. The organic group in the polyorganosiloxane as the base polymer of the component (a) used in such various reaction mechanisms is a monovalent substituted or unsubstituted hydrocarbon group, methyl group, ethyl group, propyl group, Unsubstituted hydrocarbon groups such as alkyl groups such as butyl, hexyl and dodecyl, aryl groups such as phenyl, aralkyl groups such as β-phenylethyl and β-phenylpropyl, and chloromethyl And a substituted hydrocarbon group such as 3,3,3-trifluoropropyl group. In general, methyl groups are frequently used because of their ease of synthesis. Hereinafter, (a) the base polymer and (b) the curing agent in each of the reaction mechanisms (1) to (3) will be described.

  First, in the case of applying the crosslinking method of (1), usually, as the base polymer of component (a), at least two of the organic groups bonded to the silicon atom in one molecule are vinyl, propenyl, Polyorganosiloxanes that are alkenyl groups such as butenyl and hexenyl are used. Of these groups, a vinyl group is particularly preferred because of ease of synthesis and availability of raw materials. The curing agent for component (b) includes benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl peroxide. Various organic peroxide vulcanizing agents such as hexane and di-t-butyl peroxide are used and give particularly low compression set. Therefore, dicumyl peroxide, cumyl-t-butyl peroxide, 2,5-dimethyl- 2,5-di-t-butylperoxyhexane and di-t-butylperoxide are preferable. These organic peroxide vulcanizing agents are used as one kind or a mixture of two or more kinds.

  The blending amount of the organic peroxide that is the curing agent of the component (b) is preferably in the range of 0.05 to 15 parts by weight with respect to 100 parts by weight of the base polymer of the component (a). When the amount of the organic peroxide is less than 0.05 parts by weight, the vulcanization is not sufficiently performed, and when the amount exceeds 15 parts by weight, there is no particular effect. This is because physical properties may be adversely affected.

  When the condensation reaction (2) is applied, a polyorganosiloxane having hydroxyl groups at both ends is used as the base polymer of the component (a). As the curing agent for component (b), first, as a crosslinking agent, ethyl silicate, propyl silicate, methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, methyltris (methoxyethoxy) silane, vinyltris ( Alkoxy types such as methoxyethoxy) silane and methyltripropenoxysilane; Acetoxy types such as methyltriacetoxysilane and vinyltriacetoxysilane; Methyltri (acetoneoxime) silane, Vinyltri (acetoneoxime) silane, Methyltri (methylethylketoxime) Examples include silane, vinyltri (methylethylketoxime) silane, and partial hydrolysates thereof. Hexamethyl-bis (diethylaminoxy) cyclotetrasiloxane, tetramethyldibutyl-bis (diethylaminoxy) cyclotetrasiloxane, heptamethyl (diethylaminoxy) cyclotetrasiloxane, pentamethyl-tris (diethylaminoxy) cyclotetrasiloxane, hexamethyl-bis ( Examples thereof include cyclic siloxanes such as methylethylaminoxy) cyclotetrasiloxane and tetramethyl-bis (diethylaminoxy) -mono (methylethylaminoxy) cyclotetrasiloxane. Thus, the cross-linking agent may be either a silane or siloxane structure, and the siloxane structure may be linear, branched or cyclic. Furthermore, when using these, it is not necessary to be limited to one type, and two or more types can be used together.

  In particular, as described above, the present invention is preferably applied to a composition containing a ketoxime group-containing organosilane and / or a partially hydrolyzed condensate thereof, which has not been able to obtain an excellent antifungal property in the prior art.

  Among the curing agents of component (b), the curing catalyst includes iron octoate, cobalt octoate, manganese octoate, succinate, tin caprylate, tin oleate, and carboxylic acid metal salts such as dimethyltin dioleate, Organotin compounds such as dimethyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate Used. Of the curing agent (b), the amount of the crosslinking agent is preferably 0.1 to 20 parts by weight per 100 parts by weight of the base polymer (a). If the amount of the crosslinking agent used is less than 0.1 parts by weight, sufficient strength cannot be obtained in the cured rubber, and if it exceeds 20 parts by weight, the resulting rubber becomes brittle, both of which are difficult to withstand practical use. The amount of the curing catalyst is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the base polymer of component (a). If the amount is less than this, it is insufficient as a curing catalyst, and it takes a long time for curing, and curing in the interior far from the contact surface with air becomes poor. On the other hand, when it is more than this, the storage stability is lowered. A more preferable blending amount range is 0.1 to 3 parts by weight.

  As the base polymer of component (a) when applying the addition reaction of (3) above, the same base polymer as in (1) above is used. In addition, as the curing agent of component (b), a platinum-based catalyst such as chloroplatinic acid, platinum olefin complex, platinum vinylsiloxane complex, platinum black, platinum triphenylphosphine complex is used as a curing catalyst, and as a crosslinking agent. Polyorganosiloxane having an average number of hydrogen atoms bonded to silicon atoms exceeding at least two per molecule is used. Of the curing agent of component (b), the blending amount of the curing catalyst is preferably in the range of 1 to 1000 ppm in terms of platinum element relative to the base polymer of component (a). If the blending amount of the curing catalyst is less than 1 ppm as the platinum element amount, the curing does not proceed sufficiently, and if it exceeds 1000 ppm, no improvement in the curing rate can be expected. The amount of the crosslinking agent is preferably such that the number of hydrogen atoms bonded to silicon atoms in the crosslinking agent is 0.5 to 4.0 with respect to one alkenyl group in component (a), More preferably, the amount is 1.0 to 3.0. When the amount of hydrogen atoms is less than 0.5, the curing of the composition does not proceed sufficiently, the hardness of the composition after curing is reduced, and the amount of hydrogen atoms is 4.0. When it exceeds, the physical property and heat resistance of the composition after hardening will fall.

Next, imazalil, a characteristic component of the present invention, is a compound obtained by reacting dichlorobenzene and imidazole as main raw materials [1 (2- (2,4-dichlorophenyl) -2- (2-propenyloxy) ethyl]. it is a _{C 14 H 14 Cl 2 N 2} O];) -1H- imidazole. Imazaril is a fungicide used in food applications, and various commercially available products can be easily obtained.

  In the present invention, the amount of imazalil is 0.01 to 10 parts by weight, preferably 0.1 to 5.0 parts by weight, based on 100 parts by weight of the silicone rubber base polymer.

  If the amount is less than 0.01 part by weight, it is difficult to impart mold prevention, and if it exceeds 10 parts by weight, the mechanical properties of the rubber-like elastic body after curing are significantly lowered.

  Imazaril has a high antifungal effect and exhibits excellent antifungal properties when used in relatively small amounts.

  The silicone rubber composition of the present invention may optionally contain a filler, a pigment, a heat resistance improver, a flame retardant, etc., as long as it does not impair the effects of the present invention. May be used in combination. Such materials usually include reinforcing fillers such as fumed silica, precipitated silica, diatomaceous earth, titanium oxide, aluminum oxide, zinc oxide, iron oxide, cerium oxide, mica, clay, zinc carbonate, carbonate Examples include manganese, cerium hydroxide, glass beads, polydimethylsiloxane, and alkenyl group-containing polysiloxane.

  In particular, it is preferable to use finely powdered silica, and about 12 to 50 parts by weight is blended with 100 parts by weight of the silicone rubber base polymer. Silica to be used may be untreated, surface-treated with hexamethyldisilazane or the like, or hydrophobized.

  Moreover, it is also preferable to mix | blend about 0.01-15 weight part aminosilane and / or epoxysilane with respect to 100 weight part of silicone rubber base polymers in the composition of this invention.

Examples of the present invention will be described below. In the following text, all “parts” indicate “parts by weight”.
Example 1
Uniform mixing of 100 parts of dimethylpolysiloxane having a viscosity of 3000 cP with both ends of the molecular chain blocked with silanol groups and a viscosity of 3000 cP and 6.8 parts of methyltri (methylethylketoxime) silane as a crosslinking agent in a state where moisture is previously blocked. Next, 12 parts of finely divided silica, 0.07 part of dibutyltin dilaurate as a crosslinking catalyst, 1 part of imazalil, and 0.35 part of a heated mixture of aminosilane and epoxysilane were uniformly mixed in a state where moisture was blocked. This composition was processed into a rubber sealant having a thickness of 1 mm and a length of 10 cm, and the mold resistance was evaluated.

  The test method was in accordance with JIS Z 2911, but the test strains were Alternaria steiae (NBRC3112), Ulocladium botrytis (NBRC5370), Poma citriccarpa (NBRC5287), Aspergillus niger63 (Bc).

As a result, no mold was formed on the surface of the sealant and the inhibition circle was formed in the culture for 28 days.
Comparative Example 1
A composition and a rubber sealant were prepared in the same manner as in Example 1 except that benzimidazolecarbamic acid methyl ester was used instead of imazalyl, and the mold resistance was evaluated.

  As a result, molds grew on the surface of the sealant after 28 days of culture against Alternaria steiae (NBRC3112) and Ulocladium botrytis (NBRC5370).

Claims (1)

An antifungal silicone rubber composition comprising 0.01 to 10 parts by weight of imazalil per 100 parts by weight of a silicone rubber base polymer.