JPH04366171A - Production of room-temperature-curable organo-polysiloxane composition - Google Patents

Abstract

PURPOSE:To produce the title composition effectively the slump value and improved in transparency and storage stability by mixing a mixture of a specified organopolysiloxane with a specified silica powder with a condensation catalyst. CONSTITUTION:A hydroxy-terminated polysiloxane is reacted with a reactive organosilicon compound to obtain an organopolysiloxane (A) of the formula [wherein X is acyloxy. alkoxy, alkenyloxy or ketoxyimine; R<1> and R<2> are each an (un)substituted monovalent organic group; n is a positive integer; and a is 2 or 3]. 100 pts.wt. component A is homogeneously mixed with 1-50 pts.wt. silica powder having a specific surface area of 50m<2>/g or above and an adsorbed water content of 0.5wt.% or below, and the formed mixture is mixed with 0.001-10 pts.wt. condensation catalyst.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for producing a room-temperature-curable organopolysiloxane composition that is easily cured by moisture to form a cured product of rubber elastic body.
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

[Prior Art] Conventionally, room-temperature-curing organopolysiloxane compositions that are easily cured by moisture to form cured rubber elastic materials have been used as adhesives, coating materials, electrically insulating sealing materials, and industrial or architectural sealing materials. etc. are widely used. Among these, when used as an industrial or architectural sealant, it is required that there is no slump when uncured.

[0003] In order to obtain such slump-free compositions, an anti-slump agent is usually added. Examples of the slump inhibitor include polysiloxane having a phenyl group (U.S. Pat. No. 4,100,129), polyoxyalkylene compound (Japanese Unexamined Patent Publication No. 56-85
3), a polyoxyalkylene compound having a hydrolyzable silicon-containing organic group at the end of the molecule (JP-A No. 62-1
35560) etc. are known.

[0004] A method of obtaining a room-temperature curable composition without slump without using a slump inhibitor is also known. For example, Japanese Patent Laid-Open No. 02-41361 discloses a method in which an organopolysiloxane having a hydroxyl group and a crosslinking agent are used. Mix in advance,
A method has been proposed in which finely powdered silica, a curing catalyst, etc. are then mixed therein.

[0005]

[Problems to be Solved by the Invention] However, the above-mentioned various slump inhibitors have a problem of poor compatibility with organopolysiloxane, which is the base polymer of the composition, and reduce the transparency of the composition. Ta. Furthermore, when using these anti-slump agents, it is necessary to treat the surface of the finely powdered silica used as a filler with an organosilicon compound such as dimethyldichlorosilane, thereby avoiding the cost disadvantage. There wasn't. That is, when untreated finely powdered silica, which is low in cost, is used as a filler, there is a problem in that the effect of preventing slump is not sufficiently exhibited.

Furthermore, the above-mentioned method of obtaining a room-temperature curable composition without slump without using a slump inhibitor can only be applied to oxime-free type compositions, and furthermore, the obtained composition has poor transparency and is difficult to store. There were also problems with sexuality.

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

[0008]

[Means for achieving the object] According to the present invention, the following general formula (1),

[Formula 1] (wherein, X is an acyloxy group, an alkoxy group,
Represents any group selected from the group consisting of alkenyloxy groups and ketooxyimino groups, multiple Xs may be the same or different from each other, and R1 and R2 are:
100 parts by weight of organopolysiloxane (A) represented by the same or different unsubstituted or substituted monovalent organic groups, n is a positive integer, and a is 2 or 3, and a specific surface area of 50 m2 / Adsorbed water is 0.g or more.
A room-temperature-curable organopolysiloxane characterized in that 1 to 50 parts by weight of silica powder (B) of 5% or less are mixed uniformly, and then a condensation catalyst (C) is mixed in a proportion of 10 parts by weight or less. A method of making a composition is provided.

As described above, the present invention uses an organopolysiloxane having a reactive organic group at the molecular end as a base polymer, and as a filler, fine powder silica whose adsorbed water content is adjusted to a certain value or less is used as a filler. The above-mentioned objective was successfully achieved by using a method of uniformly mixing these in advance and then adding a condensation catalyst.

(A) Organopolysiloxane The organopolysiloxane of component (A) used as the base polymer in the present invention is represented by the general formula (1). As is clear from the general formula (1), this organopolysiloxane has a reactive organic group ing. That is, when an organopolysiloxane having a hydroxyl group at the end of the molecular chain is used as a base polymer, it is necessary to incorporate an excessive amount of a crosslinking agent, which impairs the transparency of the cured product. This is extremely advantageous in terms of transparency, since it is not necessary to incorporate a crosslinking agent.

In this 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, a propoxy group,
Examples include alkenyloxy groups such as vinyloxy groups and propenyloxy groups, and ketooxyimino groups such as methylethylketooximino groups.

In the general formula (1), the groups R1 and R2 include methyl group, ethyl group, propyl group,
Alkyl groups such as butyl groups, aryl groups such as phenyl groups and tolyl groups, alkenyl groups such as vinyl groups and allyl groups, cycloalkyl groups such as cyclohexyl groups, aralkyl groups such as benzyl groups and phenylethyl groups, and Examples include groups in which part or all of hydrogen atoms are substituted with halogen atoms, cyano groups, etc., such as those having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, such as chloromethyl group, trifluoropropyl group, and cyanoethyl group. can do.

Furthermore, n is determined from the viewpoint of viscosity, workability, etc.
It is suitable that it is in the range of 50 to 2000.

[0014] The organopolysiloxane preferably used in the present invention is not limited thereto, but includes, for example, those represented by the following formula (2).

[0015]

[Case 2]

In the above formula, Me represents a methyl group, Et represents 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, which is usually used as a crosslinking agent, using a catalyst if necessary. For example, when the reactive organic group X is an acyloxy group or a ketooxyimino group, the reactive organic group It will be done. When the reactive organic group X is an alkoxy group, it can be obtained by reacting a terminal hydroxypolysiloxane and an alkoxysilane at 150° C. or higher for 24 hours or longer. Furthermore, when the reactive organic group X is an alkenyloxy group, 2
It can be obtained by removing the catalyst under reduced pressure after reacting for ~4 hours.

(B) Fine powder silica In the present invention, the specific surface area is 50 m2 /g or more,
Preferably, finely powdered silica of 100 m2/g or more is used as a filler, but this finely powdered silica has an adsorbed moisture content of 0.5% or less, particularly 0.2% or less. is important. This amount of adsorbed water is 0
．． If it is more than 5%, the storage stability of the resulting composition will be reduced. The amount of adsorbed water can be measured, for example, by the Grignard method, and the amount of adsorbed water can be easily adjusted by heating and drying.

Further, in the present invention, as long as the specific surface area and adsorbed water content are within the above ranges, dry silica,
Wet silica, calcined silica, etc. can be used as they are without any special surface treatment, which is extremely advantageous economically. Of course, the surface of these fine powdered silica
Surface-treated silica treated with organochlorosilanes, polyorganosilanes, or organosilazanes can also be used.

The above-mentioned fine powder silica is used in an amount of 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of component (A). This usage amount is 1
If it is less than 50 parts by weight, the cured product formed from the resulting composition will have unsatisfactory mechanical strength, and if it is more than 50 parts by weight, the resulting composition will have extremely poor fluidity. This makes it difficult to use as a sealant.

(C) Condensation Catalyst In the present invention, the condensation catalyst (Component (C)) is used to accelerate the curing of the composition. The existing one will be used. For example, dibutyltin dimethoxide, dibutyltin diacetate, dibutyltin dioctoate,
Organotin compounds such as dibutyltin dilaurate, dimethyltin dimethoxide, dimethyltin diacetate,
Tetrapropyl titanate, tetrabutyl titanate,
Organic titanium compounds such as tetra-2-ethylhexyl titanate and dimethoxytitanium diacetylacetonate, amine compounds such as hexylamine, 3-aminopropyltrimethoxysilane, and tetramethylguanidylpropyltrimethoxysilane, and salts thereof, etc. alone or in combination. Used in combinations of more than one species. This condensation catalyst is the above-mentioned (A
) component: 10 parts by weight or less, preferably 0.001 to 10 parts by weight, particularly preferably 0.001 to 10 parts by weight.
It is used in a proportion of 0.01 to 2 parts by weight. This usage amount is 10
If the amount is more than 1 part by weight, curing failure will occur and the sealant will not exhibit sufficient performance.

Preparation of Composition In the method of the present invention, the organopolysiloxane as component (A) and the finely powdered silica as component (B) are uniformly mixed in advance, and then the condensation catalyst as component (C) is mixed. As a result, a room-temperature-curable organopolysiloxane composition in which slump is effectively suppressed and also has excellent transparency and storage stability can be obtained. Although it is not clear why a composition with suppressed slump can be obtained by employing such a mixing method, it is not clear why a composition with suppressed slump can be obtained, but it is not clear why a composition with suppressed slump can be obtained. Di- to tetrafunctional silane as a curing agent (A)
This is thought to be due to the fact that the thixotropic properties of component (A) and component (B) are improved due to the absence of component (B) at the time of mixing. For example, (A) to (C) may be mixed at the same time, or (A) and (C) may be mixed and then (B) may be mixed.
), it becomes difficult to obtain a room-temperature curable composition without slump. Further, in the present invention, the mixing with components (A) and (B) and the subsequent mixing with component (C) are usually carried out under the exclusion of moisture.

Various compounding agents In the present invention, various fillers, pigments, dyes, adhesion agents, rust preventives, anti-mold agents, heat resistance improvers, and hardening agents may be used as long as the purpose of preventing slump etc. is not impaired. Combination agents known per se such as a repellent and a water repellent can be used. Furthermore, in order to further improve the storage stability of the composition, organosilicon compounds having two or more hydrolyzable groups in one molecule and their partial hydrolysates, which are usually used as crosslinking agents, may be added. is also possible. In the present invention, in order to fully exhibit slump prevention performance, these compounding agents that are blended as necessary are components (A) and (B).
) is preferably added at a stage after completion of uniform mixing.

When the composition thus obtained is exposed to the atmosphere, it is easily cured at room temperature by the moisture present in the air to form a rubber elastic cured product. As is clear from the following examples, such a room temperature curable composition has the following properties:
It effectively suppresses slump and has excellent preservability and transparency, making it extremely useful as a sealing material for buildings, for example.

[0025]

EXAMPLES In the following examples, "parts" means "parts by weight" and the viscosity values are measured at 25°C.

Synthesis Example 1 In a 2 liter glass flask equipped with a cooling tube,
α,ω-dihydroxydimethylpolysiloxane (viscosity 2
0000cSt, hereinafter referred to as oil A) 1500g
and add 150g of tetramethoxysilane (TMS),
The reaction was carried out at 140°C for 28 hours. After the reaction is completed, 14
By removing excess TMS and low fractions at 0° C. and under reduced pressure of 10 mmHg, a colorless and transparent oil (hereinafter referred to as oil B) with a viscosity of 22,000 cSt was obtained. I
From the R and NMR analysis results, this oil B has the hydroxyl group at the molecular end of the polysiloxane of oil A disappeared,
It was confirmed that a methoxy group was introduced.

Synthesis Example 2 In a 2 liter glass flask equipped with a cooling tube,
Oil A 1500g and methylethylketoximinosilane (MKS) 45
g was added thereto, and the mixture was reacted at 70°C for 2 hours. After the reaction is complete,
By removing low fractions at 140° C. and under reduced pressure of 10 mmHg, a colorless and transparent oil (hereinafter referred to as oil C) with a viscosity of 21,000 cSt was obtained. IR and NM
From the analysis results with R, it was confirmed that in this oil C, the hydroxyl group at the molecular terminal of the polysiloxane of 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,
Oil A 1500g Vinyltriisopropenyloxysilane (VIS)
75g of triethylamine and 15g of triethylamine were added, and the mixture was reacted at 120°C for 2 hours. After the reaction, excess VIS was removed at 140°C and under a reduced pressure of 10 mmHg.
The viscosity was reduced to 24,000cS by removing the
A colorless and transparent oil (hereinafter referred to as oil D) was obtained. From the IR and NMR analysis results, it was confirmed that in this oil D, the hydroxyl group at the molecular terminal of the polysiloxane of the oil A had disappeared, and an isopropenyloxy group had been introduced.

Example 1, Comparative Example 1 Oil B obtained in Synthesis Example 1 100 parts Specific surface area 150
m2/g, 10 parts of dry silica fine powder (surface treated with hexamethyldisiloxane, silica A) with adsorbed moisture 0.1% by weight (hereinafter simply referred to as %) was mixed at 10 mmHg with a moisture-proof universal mixer. The mixture was mixed for 15 minutes under reduced pressure. Next, 1 part of tetrapropoxytitanium (TPT, condensation catalyst) and 3 parts of vinyltrimethoxysilane (VMS, crosslinking agent) were mixed under reduced pressure of 10 mmHg to obtain composition (a) (Example 1). Also, for comparison, oil A 100
and 10 parts of silica A were mixed for 15 minutes under reduced pressure to 10 mmHg in a moisture-proof universal mixer. Next, 6 parts of tetramethoxysilane as a crosslinking agent and 1 part of TPT as a condensation catalyst were mixed under reduced pressure to 10 mmHg to obtain a composition (b) (Comparative Example 1). A slump test was conducted on these compositions in accordance with JIS-A-5758. In addition, these compositions were coated with a thickness of 2 mm.
The obtained cured product was molded into a sheet shape and cured at 20°C and 55% RH for 7 days according to JIS-K-63.
Rubber physical properties were measured in accordance with 01. Further, a portion of each composition was kept sealed in a dryer at 70° C. for 7 days to accelerate deterioration, and the physical properties of the rubber were similarly measured to examine storage stability. In addition, the transparency of the cured product is 4
The light transmittance at 00 nm was evaluated by measuring with a self-recording spectrophotometer. These results are shown in Table 1.

Example 2, Comparative Example 2 100 parts of oil C obtained in Synthesis Example 2 Specific surface area: 20
9 parts of dry silica fine powder (surface untreated, silica B) having an area of 0 m2/g and an adsorbed water content of 0.1% were mixed for 15 minutes under reduced pressure to 10 mmHg in a moisture-proof universal mixer. Then, dibutyltin octoate (BTO, condensation catalyst) 0.
1 part of MKS (crosslinking agent) and 3 parts of MKS (crosslinking agent) were mixed under reduced pressure of 10 mmHg to obtain composition (c) (Example 2). Also, for comparison, oil C 100
100 parts of oil A and MKS
A composition (d) was obtained by uniformly mixing all the components in the same manner as in Example 2, except that the amount used was 8 parts. These compositions were subjected to the same measurements as in Example 1, and the results are also shown in Table 1.

Example 3, Comparative Example 3 Oil D obtained in Synthesis Example 3 100 parts Specific surface area 120
m2/g, dry silica fine powder with adsorbed moisture 0.1% (
Surface treated with octamethylcyclotetrasiloxane, 12 parts of silica C) were mixed for 15 minutes under reduced pressure to 10 mmHg in a moisture-tight universal mixer. Next, 0.5 part of N-trismethoxysilylpropyltetramethylguanidine (TTG, condensation catalyst) and 3 parts of VIS (crosslinking agent) were mixed under 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 prevention agent, TEG)
0.3 parts were mixed for 15 minutes in a moisture-tight universal mixer under vacuum of 10 mmHg. Then, VIS as a crosslinking agent
9 parts and 0.5 g of TTG as a condensation catalyst in a 10 mm
They were mixed under reduced pressure of Hg to obtain composition (F) (Comparative Example 3). These compositions were subjected to the same measurements as in Example 1, and the results are also shown in Table 1.

[0032]

[Table 1]

[0033]

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

Claims (2)

[Claims] Claim 1: The following general formula (1): [Formula 1] (wherein, X represents any group selected from the group consisting of an acyloxy group, an alkoxy group, an alkenyloxy group, and a ketoximino group, and X may be the same or different from each other, R1 and R2 are the same or different unsubstituted or substituted monovalent organic groups, n is a positive integer, and a is 2 or 3). 100 parts by weight of organopolysiloxane (A) and 1 to 50 parts by weight of silica powder (B) having a specific surface area of 50 m2/g or more and adsorbed water of 0.5% or less are mixed uniformly, and then condensation is carried out. A method for producing a room-temperature-curable organopolysiloxane composition, which comprises mixing a catalyst (C) in a proportion of 10 parts by weight or less. 2. A room temperature curable organopolysiloxane composition obtained by the method of claim 1.