JP2683776B2 - Sealing composition - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a sealing composition, and more particularly to a sealing composition that is cured by water in the air at room temperature and prevents sagging when used as a sealing material. Composition.

[Technical Background of the Invention and its Problems] Conventionally, a so-called condensation reaction type liquid silicone rubber composition which is cured at room temperature by moisture in the air to form a rubber elastic body is well known, and is widely used in architecture, machinery, and electricity. It is widely used as a sealing material, an industrial adhesive, a potting material, a molding agent and the like in various fields such as.

By the way, when such a silicone rubber composition is used as a sealing material for industrial or architectural purposes, for construction, etc., it is difficult for the applied silicone rubber to hang down from the construction surface in an uncured state. Important from the point.

Therefore, it is common to add silica or the like treated with an organosilicon compound such as octamethylcyclotetrasiloxane as a reinforcing filler to a silicone rubber composition for a sealing material, and further compound a dripping prevention agent. It has been done.

Examples of such anti-dripping agents include polysiloxanes containing a large amount of phenyl groups (see US Pat. No. 4,100,129) and polyoxyalkylene compounds (JP-A-56).
No. 853), reaction products of polyoxyalkylene and functional silane (see JP-A-62-135560) and the like are known.

However, the above-mentioned phenyl group-containing polysiloxane does not have a sufficient sagging prevention effect even if added in a small amount, and therefore it is necessary to mix in a large amount, which causes a problem that the composition becomes extremely expensive. Further, since the polyoxyalkylene compound has a large molecular weight, the compatibility with the base polymer of the composition is poor. Further, also in the reaction product of polyoxyalkylene and functional silane, the effect is extremely small when the reinforcing filler is untreated, and there is a problem that the manufacturing process cost is increased.

[Object of the Invention] The present invention has been made in order to address such a conventional problem, and is a composition having remarkably improved drooping property while maintaining the original properties as a sealing material, particularly a reinforcing filler. An object of the present invention is to provide a sealing composition in which sagging is prevented even when an untreated material is used.

[Structure of the Invention] The present inventor has conducted diligent studies on an anti-sagging agent that achieves these objects, and as a result, polymethylsilsesquioxane powder was extremely effective. It was found that the drooling property is remarkably improved by blending an appropriate amount of sun powder, and further it was found that the same effect can be obtained even when an untreated reinforcing filler is used, and the present invention has been completed. .

That is, the present invention includes (A) at least two hydroxyl groups bonded to a silicon atom in one molecule, and the viscosity at 25 ° C is 100 to 500000 cP.
100 parts by weight of a polyorganosiloxane, which is (B) a silane containing at least two hydrolyzable groups selected from a silicon atom-bonded ketoxime group, an acyloxy group, an alkenyloxy group, an amino group and an amide group in one molecule. And / or 1 to 30 parts by weight of its partial hydrolyzed condensate, (C) 1 to 50 parts by weight of finely divided silica, and (D) 0.1 to 20 parts by weight of polymethylsilsesquioxane powder having an average particle diameter of 0.05 μm to 100 μm. Parts and (E) 0.01 to 15 parts by weight of a curable catalyst.

The polyorganosiloxane as the component (A) in the present invention serves as a base polymer for the composition of the present invention, and has been conventionally used as a base for a condensation reaction type liquid polymer.

Therefore, it is necessary to contain at least two hydroxyl groups bonded to silicon atoms in one molecule, and in order for the composition after curing to have good mechanical properties, the silicon atoms bonded to hydroxyl groups must be polyorganosiloxane. Is preferably at the end of (N is a positive integer and R is a monovalent organic group) are more preferable.

Examples of the organic group R bonded to the silicon atom of the polyorganosiloxane include a monovalent hydrocarbon group such as a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group and a phenyl group;
Examples thereof include a monovalent substituted hydrocarbon group such as a chloromethyl group, a cyanoethyl group, and a 3,3,3-trifluoropropyl group. It is preferable that 85% or more of R is a methyl group because it has an appropriate curing rate, the fluidity before curing is easy to handle for application, and the physical properties after curing, especially the modulus is low. It is best for all of R to be a methyl group from the viewpoint of easiness, but when heat resistance, cold resistance and the like are particularly required, it is better to use a phenyl group as a part of R.

Although the range of n varies depending on the type of R and its molar ratio, the viscosity of the component (A) at 25 ° C. is easy to handle, the fluidity of the sealing composition, and the physical properties after curing.
It is selected to be 100 cP to 500000 cP, and when R is all methyl groups, it corresponds to n in the range of approximately 20 to 3000.

If the viscosity of the component (A) is less than 100 cP, it becomes difficult to obtain good physical properties due to its low viscosity, and if it exceeds 500000 cP, the extrusion workability and curability tend to deteriorate. Among them, the viscosity is more preferably in the range of 500 cP to 200,000 cP.

The silane of the component (B) and its partial hydrolysis-condensation product used in the present invention are a cross-linking agent for crosslinking the component (A) to give a network structure. It is necessary to contain at least two functional groups in one molecule.

Examples of this hydrolyzable group include a ketoxime group, an acyloxy group, an alkenyloxy group, an amino group, and an amide group.

Examples of such silicon compounds include silane compounds such as methyltris (diethylketoxime) silane, methyltris (methylethylketoxime) silane, vinyltris (methylethylketoxime) silane, methyltriacetoxysilane, and methyltrivinyloxysilane, or parts thereof. An example is a hydrolysis-condensation product.

The component (B) is used in an amount of 1 to 30 parts by weight based on 100 parts by weight of the component (A). If the blending amount of the component (B) is less than 1 part by weight, a cured product excellent in elasticity and mechanical properties cannot be obtained, and if it exceeds 30 parts by weight, the resulting cured product becomes brittle.

The fine powder silica of the component (C) used in the present invention is a reinforcing filler that imparts mechanical strength to the rubber elastic body after curing, and provides a sagging prevention effect when used in combination with the component (D). But also.

Examples of such reinforcing fillers include fumed silica, calcined silica, precipitated silica, and those whose surfaces are hydrophobized with organochlorosilanes, polyorganosiloxanes, hexamethyldisilazane, and the like.

The amount of component (C) blended is in the range of 1 to 50 parts by weight, preferably 5 to 25 parts by weight, per 100 parts by weight of component (A). If the amount of the component (C) is less than 1 part by weight, sufficient mechanical strength cannot be obtained and dripping cannot be sufficiently prevented. Also, if it exceeds 50 parts by weight, mixing becomes difficult,
The compound becomes too hard to obtain the proper viscosity as a sealing material.

The polymethylsilsesquioxane fine powder of the component (D) used in the present invention remarkably improves the sagging of the sealing composition when used in combination with the fine powder silica of the component (C). Is a characteristic component in. The effect of preventing the sagging is similarly obtained even when the finely divided silica as the component (C) is not treated.

This polymethylsilsesquioxane powder, for example, Belgian Patent No. 572,412, JP 54-72300 JP, JP 60-13813 JP, JP 63-77940 JP etc. As is known, it is obtained by hydrolyzing and condensing a trifunctional silane. In addition,
As described in JP-A-60-13813 and JP-A-63-77940, alkoxysilane or its hydrolysis
The one obtained by hydrolyzing and condensing the condensate in an aqueous solution of ammonia or amines is preferable because it has few impurities such as alkaline earth metals and has a regular powder shape.

The average particle size of this polymethylsilsesquioxane powder is in the range of 0.05 μm to 100 μm, preferably 0.1 μm to 20 μm. If the average particle size is less than 0.05 μm, it is difficult to manufacture and filling is difficult, and if it exceeds 100 μm, the effect of preventing sagging is poor.

The amount of component (D) blended is in the range of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of component (A). If the amount of component (D) is less than 0.1 parts by weight, the effect of preventing sagging will not be obtained sufficiently, and if it exceeds 20 parts by weight, the reinforcing property as a sealing material will be impaired and the effect of preventing sagging will also be lost. On the contrary, it gets worse.

The component (E) curing catalyst used in the present invention is
It promotes the condensation reaction between component (A) and component (B).

Such curing catalysts include carboxylic acid metal salts such as iron octoate, cobalt octoate, manganese octoate, zinc octoate, tin naphthenate, tin caprylate, tin oleate; dibutyltin diacetate, dibutyltin dioctoate, dibutyltin laurate. , Organotin compounds such as dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate; tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate , Organic titanic acid esters such as tetra (isopropenyloxy) titanate; organosiloxy titanium, β-carbonyl titanium, etc. Titanium compounds; and alkoxy aluminum compounds.

The amount of component (E) compounded is in the range of 0.01 to 10 parts by weight per 100 parts by weight of component (A). When the compounding amount of the curing catalyst exceeds 10 parts by weight, not only the curability becomes too fast but also the mechanical properties of the cured sealant are adversely affected.

Incidentally, the sealing composition of the present invention, if necessary, other known fillers, plasticizers, colorants, heat resistance improvers,
A flame retardant-imparting agent, an adhesion-imparting agent and the like may be added within a range that does not impair the effects of the present invention.

The sealing composition of the present invention is prepared by blending the components (A) to (E) and, if necessary, the above-mentioned additives and the like in a predetermined amount, and mixing them with a mixer, a kneader or the like in a state where moisture is cut off. It can be obtained by homogenizing.

[Effects of the Invention] The sealing composition of the present invention is sufficiently prevented from sagging during construction, and has extremely excellent workability when used as various sealing materials such as architectural sealing materials. ing. Moreover, the sealing composition of the present invention, even when using untreated fine powder silica as a reinforcing filler, drastically improves sagging, and the manufacturing cost thereof is further reduced. It is very useful as a sealing material.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. All parts in the examples and comparative examples indicate parts by weight.

First, polymethylsilsesquioxane was synthesized by the following method.

[Synthesis of polymethylsilsesquioxane powder]

Polymethylsilsesquioxane was synthesized by hydrolyzing and condensing 100 parts of methyltrimethoxysilane in 400 parts of 5% aqueous ammonia solution. The obtained polymethylsilsesquioxane was dried and further pulverized to obtain polymethylsilsesquioxane powder powder P-1 having an average particle diameter of 2 μm.

Examples 1 to 3 As components (A), both ends of the molecular chain are blocked with hydroxyl groups,
Polydimethylsiloxane with viscosity of 30,000cP at 25 ℃ 1
To 00 parts, fumed silica Aerosil 200 (trade name, manufactured by Nippon Aerosil Co., Ltd.) treated with methyltris (methylethylketoxime) silane as the component (B) and octamethylcyclotetrasiloxane as the component (C) and (D) Polymethylsilsesquioxane fine powder P-1 synthesized by the above-mentioned method as a component was mixed in a kneader in an amount shown in Table 2 and then mixed so as to be uniform in a state where moisture was cut off, Further, as components (E), dibutyltin dioctoate was blended and mixed in the amounts shown in Table 2, and then defoamed to obtain three kinds of sealing compositions (Examples 1 to 3).

Further, for comparison with the present invention, sealing compositions (Comparative Examples 1 and 2) were prepared with the same blending amount and the same method except that the component (D) was not blended in the above Examples.

Using each of these sealing compositions, a slump test of 30 mm width and 50 mm width was conducted according to JIS A 5758. The results are also shown in Table 1.

From the results of each of the above Examples and Comparative Examples, the sealing composition of the present invention, while satisfying the properties such as mechanical strength originally required as a sealing material, drooping before curing is significantly improved, It is clear that workability is excellent.

Claims (1)

(57) [Claims] 1. A hydroxyl group bonded to a silicon atom is
Contains at least 2 in the molecule and has a viscosity at 25 ℃ of 10
100 parts by weight of a polyorganosiloxane having 0 to 500000 cP, (B) at least two hydrolyzable groups selected from a ketoxime group, an acyloxy group, an alkenyloxy group, an amino group and an amide group bonded to a silicon atom in one molecule. 1 to 30 parts by weight of silane and / or its partial hydrolyzed condensate, (C) 1 to 50 parts by weight of finely divided silica, (D) 0.1 to 100 of polymethylsilsesquioxane powder having an average particle size of 0.05 to 100 μm A sealing composition comprising 20 parts by weight and (E) 0.01 to 10 parts by weight of a curing catalyst.