JP2582685B2 - Method for producing room temperature curable organopolysiloxane composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a room-temperature-curable organopolysiloxane composition which is easily cured by moisture to form a cured rubber elastic material,
More specifically, the present invention relates to a method for producing a room temperature curable organopolysiloxane composition in which slump in a compound state is effectively suppressed.

[0002]

2. Description of the Related Art Conventionally, room temperature-curable organopolysiloxane compositions which are easily cured by moisture to form a cured product of a rubber elastic material have been used for adhesives, coating materials, electrically insulating seal materials, industrial or architectural sealing materials. Widely used for materials. Among these, when used for industrial or architectural sealing materials, it is required that there be no slump when uncured.

In order to obtain such a composition without slump, a slump inhibitor is usually added. Examples of the anti-slump agent include polysiloxane having a phenyl group (U.S. Pat. No. 4,100,129), polyoxyalkylene compound (JP-A-56-853),
There are known polyoxyalkylene compounds having a hydrolyzable silicon-containing organic group at the molecular terminal (JP-A-62-135560).

There is also known a method of obtaining a room temperature curable composition without slump without using a slump inhibitor. For example, JP-A-02-41361 discloses a method in which an organopolysiloxane having a hydroxyl group and a crosslinking agent are used. A method has been proposed in which the powder is mixed in advance and then mixed with fine powder silica, a curing catalyst and the like.

[0005]

However, the above-mentioned various anti-slump agents have a problem in that they have poor compatibility with the organopolysiloxane which is the base polymer of the composition and lower the transparency of the composition. Was. In addition, when these slump inhibitors are used, it is necessary to treat the surface of the finely powdered silica used as the filler with an organosilicon compound such as dimethyldichlorosilane, which avoids the disadvantage of cost. Did not. That is, when untreated fine powdered silica having low cost is used as a filler, there is a problem that the effect of preventing slump is not sufficiently exhibited.

Further, the above-mentioned method of obtaining a room-temperature curable composition without slump without using a slump inhibitor can be applied only to a deoxime-type composition, and the obtained composition has poor transparency and can be stored. There was also a problem with gender.

Accordingly, an object of the present invention is to provide a method for producing a room-temperature-curable organopolysiloxane composition in which slump is effectively suppressed without using a slump inhibitor and which is excellent in transparency and storage stability. It is to be.

[0008]

According to the present invention, the following general formula (1):

Embedded image (Wherein, X is an acyloxy group, an alkoxy group, any group selected from the group consisting of alkenyloxy group and Ketookishiimino group, a plurality of X may be the same or different, R ¹ and R ² is the same or different unsubstituted or substituted monovalent organic group, n is a positive integer and a is 2 or 3), and 100 parts by weight of the organopolysiloxane (A) Surface area 50m ² /
g and more than 0.5% silica powder (B) 1-50
Parts by weight, and thereafter, the condensation catalyst (C) is mixed at a ratio of 10 parts by weight or less, thereby providing a method for producing a room-temperature-curable organopolysiloxane composition.

According to the present invention, there is provided finely divided silica having an organopolysiloxane having a reactive organic group at its molecular terminal as a base polymer and having a fixed amount of water adsorbed to a fixed value or less as a filler. The above-mentioned object has been successfully achieved by adopting a method of adding a condensation catalyst after uniformly mixing these in advance.

(A) Organopolysiloxane Component Used as Base Polymer in the Present Invention
The organopolysiloxane (A) is represented by the general formula (1). As apparent from the general formula (1), this organopolysiloxane has a reactive organic group X at both ends of the molecular chain, and thus has the property of being curable without a special crosslinking agent. ing. That is, when an organopolysiloxane having a hydroxyl group at a molecular chain terminal is used as a base polymer, it is necessary to add an excessive amount of a cross-linking agent, thereby impairing the transparency of the cured product. In this case, since it is not necessary to add a crosslinking agent, this is extremely advantageous in terms of transparency.

In the general formula (1), the reactive organic group X includes an acyloxy group such as an acetoxy group, an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group, and an alkenyloxy group such as a vinyloxy group and a propenyloxy group. And a ketooxyimino group such as a methylethylketooximino group.

In the general formula (1), the groups R ¹ and R ²
As an alkyl group such as methyl group, ethyl group, propyl group, butyl group, phenyl group, aryl group such as tolyl group, vinyl group, alkenyl group such as allyl group, cycloalkyl group such as cyclohexyl group, benzyl group, Aralkyl groups such as phenylethyl group and the like, and some or all of the hydrogen atoms of these groups are substituted with halogen atoms, cyano groups and the like, for example, chloromethyl group, trifluoropropyl group,
C 1-10, preferably C 1 carbon atoms such as a cyanoethyl group
To 8 can be exemplified.

Further, n is determined from the viewpoint of viscosity and workability.
Preferably it is in the range of 50-2000.

In the present invention, the organopolysiloxane preferably used is not limited to these, but examples thereof include those represented by the following formula (2).

[0015]

Embedded image

In the above formula, Me is a methyl group, Et is an ethyl group,
Vi represents a vinyl group, and Ph represents a phenyl group.

The above-mentioned organopolysiloxane can be easily obtained by heating a terminal hydroxypolysiloxane and a reactive organosilicon compound usually used as a cross-linking agent, if necessary, using a catalyst. For example, when the reactive organic group X is an acyloxy group or a ketooxyimino group, it is obtained by reacting the terminal hydroxypolysiloxane with acyloxysilane or ketooxyiminosilane at a temperature of 50 to 90 ° C. for 10 minutes to 2 hours. Can be When the reactive organic group X is an alkoxy group, it can be obtained by reacting the terminal hydroxypolysiloxane with the alkoxysilane at 150 ° C. or more for 24 hours or more. Further, when the reactive organic group X is an alkenyloxy group, it can be obtained by reacting at 50 to 90 ° C. for 2 to 4 hours using a basic compound such as triethylamine as a catalyst, and then removing the catalyst under reduced pressure. it can.

(B) Finely divided silica In the present invention, finely divided silica having a specific surface area of 50 m ² / g or more, preferably 100 m ² / g or more is used as a filler. It is important to use water with a moisture content of 0.5% or less, especially 0.2% or less. If the amount of adsorbed water is more than 0.5%, the storage stability of the obtained composition is disadvantageously reduced. The amount of adsorbed water can be measured by, for example, the Grignard method, and the amount of adsorbed water can be easily adjusted by heating and drying.

In the present invention, as long as the specific surface area and the amount of adsorbed water are within the above-mentioned ranges, fumed silica,
Wet silica, calcined silica, and the like can be used as they are without special surface treatment, which is extremely economically advantageous. Of course, the surface of these fine powder silica
Surface-treated silica treated with organochlorosilanes, polyorganosilanes, and organosilazanes can also be used.

The above-mentioned finely divided silica is a component (A)
It is used in a proportion of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 00 parts by weight. If this amount is less than 1 part by weight, the cured product formed from the resulting composition will be unsatisfactory in mechanical strength, and if it is used in excess of 50 parts by weight, the resulting composition will become fluid. The properties are extremely poor, making it difficult to use as a sealing agent.

(C) Condensation Catalyst In the present invention, the condensation catalyst of component (C) is used for accelerating the curing of the composition, and includes:
What has been conventionally used for this kind of composition is used. For example, dibutyltin dimethoxide, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dimethyltin dimethoxide,
Organotin compounds such as dimethyltin didiacetate, organic titanium compounds such as tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, dimethoxytitanium diacetylacetonate, hexylamine, 3-aminopropyltrimethoxysilane, tetramethylg Amine compounds such as anisylpropyltrimethoxysilane and salts thereof are used alone or in combination of two or more. This condensation catalyst is the same as the component (A) 1
10 parts by weight or less, preferably 0.001 to 100 parts by weight
It is used in a proportion of 10 parts by weight, particularly preferably 0.01 to 2 parts by weight. If the used amount is more than 10 parts by weight, poor curing occurs, and sufficient performance as a sealant is not exhibited.

Preparation of Composition In the method of the present invention, after the above-mentioned organopolysiloxane of component (A) and finely divided silica of component (B) are uniformly mixed in advance, the condensation catalyst of component (C) is mixed. By doing
A room-temperature-curable organopolysiloxane composition which effectively suppresses slump and has excellent transparency and preservability can be obtained. The reason for obtaining a composition in which slump is suppressed by employing such a mixing means is not clear, but it is blended with a hydroxy-terminated diorganopolysiloxane or a curable composition of this type in general. Due to the fact that thixotropic properties of the components (A) and (B) are improved due to the absence of the 2- to 4-functional silane as a curing agent when the components (A) and (B) are mixed. It seems that you are doing. For example, when the components (A) to (C) are mixed at the same time, or when the components (A) and (C) are mixed and then the component (B) is mixed, the room temperature curability without slump is used. Obtaining the composition becomes difficult. Further, in the present invention, mixing with the components (A) and (B), and
The mixing of the component (C) is usually performed under the exclusion of moisture.

Various Compounding Agents In the present invention, various fillers, pigments, dyes, adhesion-imparting agents, rust preventives, fungicides, heat-resistance improvers, and so forth are used as long as the purpose of slump prevention and the like is not impaired. Known compounding agents such as a fuel agent and a water-repellent agent can be used.
Further, in order to further improve the storage stability of the composition, an organosilicon compound having two or more hydrolyzable groups usually used as a crosslinking agent in one molecule and a partial hydrolyzate thereof are added. Is also possible. In the present invention, these compounding agents, which are necessary, may be added at a stage after the uniform mixing of the components (A) and (B) is completed in order to sufficiently exhibit slump prevention performance. preferable.

When the composition thus obtained is exposed to the atmosphere, it is easily cured at room temperature by moisture present in the air to form a rubber elastic cured product. Such a room temperature curable composition, as apparent from the following examples,
Slump is effectively suppressed and has excellent storage stability and transparency, and is extremely useful, for example, as a building sealing material.

[0025]

EXAMPLES In the following examples, "parts" means "parts by weight", and the viscosity indicates a value measured at 25 ° C.

Synthesis Example 1 α, ω-dihydroxydimethylpolysiloxane (viscosity 20) was placed in a 2-liter glass flask equipped with a cooling tube.
000 cSt, hereinafter referred to as oil A) 1500 g and tetramethoxysilane (TMS) 150 g were added and reacted at 140 ° C. for 28 hours. After the reaction, 1
By removing excess TMS and low distillate at 40 ° C. under reduced pressure of 10 mmHg, a colorless and transparent oil having a viscosity of 22,000 cSt (hereinafter referred to as “oil B”) was obtained. From the analysis results of IR and NMR, it was confirmed that the hydroxyl group at the molecular end of the polysiloxane of the oil A had disappeared and the methoxy group had been introduced in the oil B.

Synthesis Example 2 1500 g of oil A and 45 g of methyl ethyl ketooximinosilane (MKS) were added to a 2 liter glass flask equipped with a cooling tube and reacted at 70 ° C. for 2 hours. After the reaction, 140
C, under reduced pressure of 10 mmHg, by removing low distillate,
A colorless and transparent oil having a viscosity of 21,000 cSt (hereinafter referred to as oil C) was obtained. From the analysis results of IR and NMR, it was confirmed that in the oil C, the hydroxyl group at the molecular end of the polysiloxane of the oil A had disappeared and an oxime group had been introduced.

Synthesis Example 3 In a 2 liter glass flask equipped with a cooling tube, 1500 g of oil A, vinyl triisopropenyloxysilane (VIS) 75
g and 15 g of triethylamine were added and reacted at 120 ° C. for 2 hours. After the reaction, 1
By removing excess VIS and low distillate at 40 ° C. under reduced pressure of 10 mmHg, a colorless and transparent oil having a viscosity of 24000 cSt (hereinafter referred to as “oil D”) was obtained. From the analysis results by IR and NMR, it was confirmed that the oil D had the hydroxyl group at the molecular end of the polysiloxane of the oil A disappeared and the isopropenyloxy group was introduced.

Example 1, Comparative Example 1 100 parts of oil B obtained in Synthesis Example 1, specific surface area 150 m ² / g, adsorbed water 0.1% by weight (hereinafter simply referred to as%
10 parts of dry silica fine powder (surface treatment with hexamethyldisiloxane, silica A) was mixed for 15 minutes while reducing the pressure to 10 mmHg by using a universal mixer in which moisture was shut off. Next, 1 part of tetrapropoxytitanium (TPT, condensation catalyst) and 3 parts of vinyltrimethoxysilane (VMS, crosslinking agent) were mixed under a reduced pressure of 10 mmHg to obtain a composition (a) (Example 1). For comparison, 100 parts of oil A and 100 parts of silica A
10 parts were mixed for 15 minutes while reducing the pressure to 10 mmHg with a universal mixer which was kept out of moisture. Then, 6 parts of tetramethoxysilane as a cross-linking agent and 1 part of TPT as a condensation catalyst were added to 10 parts.
The composition was mixed under reduced pressure of mmHg to obtain a composition (b) (Comparative Example 1). These compositions were subjected to a slump test according to JIS-A-5758. In addition, these compositions have a thickness of 2
The molded product was molded into a sheet having a thickness of mm, cured at 20 ° C. and 55% RH for 7 days, and the physical properties of the obtained cured product were measured in accordance with JIS-K-6301. Further, a part of each composition is kept in a drier at 70 ° C. in a sealed state for 7 days to promote deterioration,
Similarly, the physical properties of the rubber were measured and the storage stability was examined. The transparency of the cured product was evaluated by measuring the light transmittance at 400 nm of the cured product having a thickness of 2 mm with a self-recording spectrophotometer. Table 1 shows the results.

Example 2, Comparative Example 2 100 parts of oil C obtained in Synthesis Example 2 9 parts of dry silica fine powder (untreated surface, silica B) having a specific surface area of 200 m ² / g and an adsorbed moisture of 0.1% While reducing the pressure to 10 mmHg with a universal mixer that shuts out moisture
Mix for 15 minutes. Next, 0.1 part of dibutyltin octoate (BTO, condensation catalyst) and 3 parts of MKS (crosslinking agent) were mixed under a reduced pressure of 10 mmHg to obtain a composition (c) (Example 2). For comparison, instead of 100 parts of oil C,
Except that 100 parts of oil A was used and the amount of MKS used was 8 parts, the same components as in Example 2 were all mixed together and uniformly mixed to obtain composition (d). For these compositions, the same measurements as in Example 1 were performed, and the results are shown in Table 1.

Example 3, Comparative Example 3 100 parts of oil D obtained in Synthesis Example 3, fine powder of dry silica having a specific surface area of 120 m ² / g and an adsorbed moisture of 0.1% (surface treatment with octamethylcyclotetrasiloxane, silica C) 12 parts were reduced to 10 mmHg with a moisture-proof universal mixer.
Mix for 15 minutes. Next, 0.5 part of N-trismethoxysilylpropyltetramethylguanidine (TTG, condensation catalyst) and 3 parts of VIS (crosslinking agent) were mixed under a reduced pressure of 10 mmHg to obtain a composition (e) (Example 3). For comparison, 100 parts of oil A, 12 parts of silica C and triethylene glycol (slump inhibitor, TEG)
Reduce 0.3 part to 10 mmHg with a universal mixer with moisture shut off.
Mix for 15 minutes. Then, 9 parts of VIS as a crosslinking agent,
0.5 g of TTG as a condensation catalyst was mixed under a reduced pressure of 10 mmHg to obtain a composition (f) (Comparative Example 3). For these compositions, the same measurements as in Example 1 were performed, and the results are shown in Table 1.

[0032]

[Table 1]

[0033]

According to the present invention, it is possible to obtain a room-temperature curable composition in which slump is effectively suppressed and transparency and storage stability are excellent without using a slump inhibitor. This composition is extremely useful, for example, as an architectural sealant.

Claims (2)

(57) [Claims] (1) The following general formula (1): (Wherein, X is an acyloxy group, an alkoxy group, any group selected from the group consisting of alkenyloxy group and Ketookishiimino group, a plurality of X may be the same or different, R ¹ and R ² is the same or different unsubstituted or substituted monovalent organic group, n is a positive integer and a is 2 or 3), and 100 parts by weight of the organopolysiloxane (A) Surface area 50m ² /
g and more than 0.5% silica powder (B) 1-50
Parts by weight, and thereafter, the condensation catalyst (C) is mixed in a proportion of 10 parts by weight or less, thereby producing a room-temperature-curable organopolysiloxane composition. 2. A room temperature curable organopolysiloxane composition obtained by the method of claim 1.