JPH0686574B2 - Room temperature curable organopolysiloxane composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a room temperature curable organopolysiloxane composition, and more particularly to a dealcohol type room temperature curable organopolysiloxane composition having excellent storage stability. .

[Prior Art] Various room-temperature-curable organopolysiloxane compositions are known, but a cross-linking agent such as methyltrimethoxysilane and an organotitanium compound or an organic polyorganosiloxane having a hydroxyl group at a molecular chain terminal are known. A composition to which a catalyst such as a titanium chelate compound is added is not corrosive and does not generate an irritating odor because it generates alcohol during curing to form a rubber-like organopolysiloxane. It is widely used as an adhesive.

However, this type of dealcohol-type room temperature curable organopolysiloxane composition (hereinafter abbreviated as RTV siloxane composition) generally has a slow curing rate, and has the disadvantages of poor internal curability and storage stability. In the case of long-term storage, even if it is in an anhydrous state, it has the drawback that it will not cure during use.

Therefore, for this type of composition, a method of using a silane compound having a dialkoxy group as a so-called silane scavenger to improve its storage stability and curability has been proposed. It is necessary to manufacture a new compound, and in order to improve the storage stability, it is necessary to use a hydrolyzable group other than the dialkoxy group of the silane compound having high reactivity such as an amide group and an amine group. However, since these groups have corrosiveness and odor, they have the disadvantage that they cannot be used as adhesives in the electrical and electronic industries.

Further, in this type of composition, a diorganopolysiloxane whose molecular chain ends are blocked with a hydroxyl group, an alkoxysilane or a partial hydrolyzate thereof and a formula [(CH ₃ ) ₂ N] C = N
It is also proposed that a guanidyl-substituted alkylalkoxysilane represented by (CH ₂ ) ₃ Si (OCH ₃ ) ₃ and an organic tin compound are added (see JP-A-58-52351), which is storage stable. Although it is said that the property is good,
Actually, the free alcohol produced by the reaction between the silanol group in the diorganopolysiloxane and the alkoxysilane or its partial hydrolyzate remains in the composition, which has the disadvantage of extremely poor storage stability. Further, there has been proposed a method in which an alkoxysilane containing an alkenyloxy group is used as a silane scavenger for a hydroxy group (JP-A-60-18546, JP-A-60-1).
However, the RTV siloxane composition containing such an alkenyloxysilane has a disadvantage that the color of the composition changes from yellow to brown during storage when stored in a sealed container. .

[Constitution of Invention] The present invention solves such disadvantages and dealcoholized RT
V siloxane composition, which is 100 parts by weight of a diorganopolysiloxane having both ends of a molecular chain blocked with a hydroxyl group or a di- or trialkoxy group, b)
^{1 to} 400 parts by weight of filler, c) the general formula R ¹ mSi (OR ² ) ₄ -m (wherein R ¹ is a monovalent hydrocarbon group, R ² is an alkyl group or an alkoxy group-substituted alkyl group, m is 0 or 1 to 50 parts by weight of an alkoxysilane represented by 1) or a partial hydrolyzate thereof, d) a general formula (R ³ ₂ N) ₂ C = N- (wherein R ³ is a hydrogen atom or a monovalent hydrocarbon group) 0.01 to 10 parts by weight of a silane or siloxane having at least one group shown in one molecule, e) 0.01 to 10 parts by weight of an organic tin compound, and f) a general formula. (Wherein R ¹ , R ² and R ³ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, R ⁴ is methyl group, vinyl group, methoxy group, A is oxygen (-0-) or -CH ₂ CH ₂ -Group, a is 0 or 1, b
Is 0.1 to 10 parts by weight of an organopolysiloxane containing at least one unit having an alkenyloxy group represented by 1, 2 or 3) in one molecule.

That is, as a result of various studies on the dealcohol-type RTV siloxane composition having excellent storage stability and solving the above-mentioned disadvantages, the present inventors have found that the conventionally known dealcohol-type RTV siloxane composition has storage stability. , The curability is poor, the reactivity of the hydroxyl group in the organosiloxane having a hydroxyl group at the terminal of the molecular chain, the alkoxy group in the silane compound having an alkoxy group to react with the water contained in the filler is low, It has been found that unreacted silanol groups remain and that free alcohol generated by the reaction of a silane compound having an alkoxy group and a silanol group is present in the composition.

Therefore, the present inventors mix the above-mentioned diorganopolysiloxane as the component a) with the filler as the component b), and then add the alkoxylane or the partial hydrolyzate thereof as the component c) and the component d). When a guanidyl group-containing silane or a siloxane as a component and an organic tin compound as a component e) are mixed while blocking air, the silanol group and water contained in the components a) and b) are alkoxy of component c). Although the silanol group disappears in the mixture by reacting with silane or its partial hydrolyzate, alcohol remains in this composition,
If this alcohol is left as it is, the preservability of the RTV siloxane composition becomes poor. Therefore, when the above-mentioned alkenyloxy group-containing organopolysiloxane as the component f) is added thereto, the guanidyl group as the component d) is added. This residual alcohol and the alkenyloxy group of the alkenyloxy group-containing organopolysiloxane are exchange-reacted with the contained silane or siloxane as a catalyst to capture the free alcohol, and the silanol group and the alcohol are not contained at all. It has been found that an RTV siloxane composition having excellent properties can be obtained, and discoloration after storage which occurs when alkenyloxysilane is used as a scavenger does not occur at all when alkenyloxysiloxane is used. Easy RTV composition with excellent curability and curability Ensure that can be obtained, the compounding ratio of the components required herein, and completed the present invention by studying about such mixing method.

The diorganopolysiloxane as the component a) constituting the composition of the present invention is the main ingredient of this composition, and the main chain portion is And R is a methyl group, an ethyl group, a propyl group,
Alkyl groups such as butyl group, 2-ethylbutyl group, octyl group, cycloalkyl groups such as cyclohexyl group, cyclopentyl group, alkenyl groups such as vinyl group, hexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, diphenyl group Such as aryl groups, benzyl groups, aralkyl groups such as phenylethyl groups, or chloromethyl groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are replaced with halogen atoms, cyano groups, trifluoropropyl, etc. Group, the same or different unsubstituted or substituted monovalent hydrocarbon group selected from 2-cyanoethyl group, 3-cyanopropyl group, etc., a is 1.90 to 2.05, hydroxyl groups or di- or trialkoxy at both ends of the molecular chain Although it is supposed to be blocked with a group, the cured product obtained from the composition of the present invention has good rubber elasticity. It indicates a viscosity at 25 ° C. This thing in order to be excellent in mechanical strength 25cS
More than that is needed.

If desired, this compound may be mixed with a diorganopolysiloxane whose molecular chain end is a group other than a hydroxyl group, a di- or trialkoxy group, for example, a trimethylsilyl group, but this amount is not limited to the above-mentioned molecular weight. It is preferable that the amount of the diorganopolysiloxane whose chain end is blocked with a hydroxyl group, a di- or trialkoxy group is equal to or less than that.

Further, the filler as the component b) in the composition of the present invention may be a known one, and it may be a fine powder silica, silica aerogel, precipitated silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide or other metal. Oxides, or those whose surfaces are silane-treated, metal carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, asbestos, glass wool, carbon black, fine mica, fused silica powder, polystyrene, polyvinyl chloride, polypropylene, etc. Synthetic resin powder of 1) is exemplified, but if the amount is 1 part by weight or less with respect to 100 parts by weight of the component a), the cured product obtained from this composition will not show sufficient mechanical strength. When the amount is 400 parts by weight or more, not only the viscosity of the room temperature curable organopolysiloxane increases and workability deteriorates, but also after curing. Since beam intensity is less likely purpose rubber elastic body is obtained of reduced, it is necessary in the range of 1 to 400 parts by weight, are the preferred range 5-200 parts by weight.

Next, the alkoxysilane as the component c) in the composition of the present invention is represented by the formula R ¹ mSi (OR ² ) ₄ -m, where R ¹ is methyl group, ethyl group, propyl group, vinyl group, phenyl group, tri group. A monovalent hydrocarbon group such as a fluoropropyl group, R ² is an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, and an alkoxyalkyl group such as a methoxyethyl group and an ethoxyethyl group. Silane, ethyltrimethoxysilane, vinyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltri (methoxyethoxy) silane, vinyltri (methoxyethoxy) Silane, tetra (ethoxyethoxy) silane, trifluoropro Le trimethoxysilane but may be those exemplified by such, they may be siloxane was them engaged partial hydrolysis condensation.

As the component c), methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltri (methoxyethoxy) silane, and vinyltri (methoxyethoxy) silane are preferable among the above. If the amount is too large, the room temperature-curable organopolysiloxane composition has poor physical properties after curing, and it is economically disadvantageous. Therefore, it is 1 to 50 parts by weight per 100 parts by weight of component a). A range of parts by weight is required.

Next, the silane or siloxane as the component d) in the composition of the present invention has one molecule represented by the general formula (R ³ ₂ N) ₂ C = N- (R ³ is a hydrogen atom or a monovalent hydrocarbon group). It is said that at least one is contained therein, which acts as a catalyst when silylating water and silanol in the base compound by the above-mentioned component c).

The above-mentioned group may be bonded to the silicon atom through any group, but it is generally preferable that the group is bonded to the silicon atom through an alkylene group or an oxyalkylene group. formula (Here, Me is a methyl group, Et is a methyl group, Pr is a propyl group, and Ph is a phenyl group.) It is preferable to use an organosilane represented by If the amount of the component d) is too small, the effect of accelerating the reaction between the base compound consisting of the components a) and b) and the component c) will be insufficient, and the reaction will take a long time. And the residual hydroxyl groups and water remain in the reaction product, which makes the composition poor in storage stability. On the other hand, if the amount is too much, the reaction becomes faster, but the reaction product discolors. There is a risk that it may be economically disadvantageous, so 0.01 to 1 per 100 parts by weight of component a)
It is necessary to set the range of 0 parts by weight, but the preferable range is 0.1 to 5 parts by weight.

Further, the organic tin compound as the component e) in this composition is known as a condensation reaction catalyst conventionally used in this type of composition, and it includes tin naphthenate, tin caprylate, and oleic acid. Tin carboxylate such as tin, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dibutyltin dibenzyl For example, malate is used, but if this amount is too small, the function as a curing catalyst is not sufficiently exhibited, the curing time becomes long, and the curing in the deep portion of the rubber layer becomes insufficient, so that the amount is large. If too much, the storage stability of this composition becomes poor, so a) component 100 With respect to the amount unit, it is necessary in the range of 0.01 to 10 parts by weight, the preferred range from 0.1 to 2
It is considered to be part by weight.

Next, the organopolysiloxane containing at least one alkenyloxy group in one molecule as the component f) in the composition of the present invention has the general formula And R ¹ , R ² , and R ³ are hydrogen atoms or have 1 to 1 carbon atoms.
4 alkyl group, R ⁴ is methyl group, vinyl group, methoxy group, A is oxygen (−0-) or —CH ₂ CH ₂ — group, a is 0 or 1, b is 1, 2 or 3 It is assumed to have at least one unit having an alkenyloxy group in one molecule, which is the diorganopolysiloxane as the component a) and the silanol group contained in the filler as the component b). , For removing alcohol generated by the reaction of water with an alkoxysilane or a partial hydrolyzate thereof as the component c), which has a guanidyl group-containing silane whose alkenyloxy group is the above-mentioned component d). Alternatively, the addition of the alkenyloxy siloxane will react with the alcohol in the presence of siloxane by its catalytic action to convert it into an alkoxysilyl group. Therefore, the composition of the present invention has excellent storage stability. Since the reaction between the alkenyloxysiloxane and the alcohol proceeds easily and stoichiometrically, the amount of the alkenyloxysiloxane added is such that the alkenyloxy group is alkenyloxy group / ROH ≧
However, if the amount is 0.1 parts by weight or less with respect to 100 parts by weight of the diorganopolysiloxane as the component a), the alcohol may remain. Since it is also disadvantageous, it may be in the range of 0.1 to 10 parts by weight, but the preferred range is 0.5 to 5 parts.
It is considered to be part by weight.

This alkenyloxy group-containing siloxane can be synthesized by addition reaction of vinyl group-terminated siloxane and hydroalkenyloxysilane in the presence of a platinum-based catalyst, which also catalyzes alkenyloxysilane and terminal hydroxyl-blocked diorganopolysiloxane. It can be easily obtained only by mixing in the presence. Specific examples of the alkenyloxy group-containing siloxane include the following: Is exemplified.

The composition of the present invention is obtained by mixing predetermined amounts of the above-mentioned components a) to f). In this production, the above-mentioned diorganopolysiloxane as the component a) and filling as the component b) are filled. A base compound is prepared by mixing the agents, and then a predetermined c) component alkoxysilane or its partial hydrolyzate and d) are added to this compound.
A guanidyl group-containing silane or siloxane as a component and an organic tin compound as a component e) were added and mixed well under a closed condition, and then an alkenyloxysiloxane as a component f) was added thereto to react with an alcohol / alkenyloxysiloxane. After that, the mixture may be mixed and stirred under reduced pressure. The composition of the present invention thus obtained, if necessary, a thixotropy-imparting agent such as polyethylene glycol and a derivative thereof, a pigment, a dye,
It is optional to add antiaging agents, antioxidants, antistatic agents, flame retardants such as antimony oxide and chlorinated paraffin, and thermal conductivity improvers such as boron nitride and aluminum oxide. It is also possible to mix various conventionally known additives such as a sonophilic agent, an amino group, an epoxy group, a thiol group, so-called carbon functional silane, a metal salt of a carboxylic acid, a metal alcoholate, etc. It may be diluted with a hydrocarbon solvent such as toluene or petroleum ether, a ketone, an ester, or the like for properness.

The composition of the present invention is a so-called RTV siloxane composition which is stable under a sealed condition and quickly hardens into an elastic body by its moisture when exposed to the air. Since it has excellent properties and curability, for example, even after storage for 6 months, it will quickly cure when exposed to air to give a cured product with excellent physical properties.
It does not release toxic or corrosive gases during curing, does not cause rust on the treated surface, and since this cured product adheres well to various substrates, especially metal surfaces, it requires electrical and electronic parts. Besides being useful as an adhesive, it also seals various substrates, caulks, coatings, water repellents,
It has the usefulness that it can be widely used as a release treatment agent and also as a fiber treatment agent.

Next, examples of the present invention will be given. Parts in the examples are parts by weight, and viscosities are measured values at 25 ° C.

Example 1 88 parts of dimethylpolysiloxane having both ends of a molecular chain blocked with hydroxyl groups and a viscosity of 20,000 cP, fumed silica having 9 parts of surface treated with trimethylsilyl group and fumed silica having surface treated with cyclic dimethylpolysiloxane 3 parts of silica was added and mixed uniformly to produce a base compound.

Then, to 100 parts of this base compound was added 5 parts of methyltrimethoxysilane, 0.5 parts of γ-tetramethylguanidylpropyltrimethoxysilane and 0.2 parts of dibutyltin dimethoxide, and the mixture was mixed under reduced pressure for 15 minutes and then mixed. 2 parts of an alkenyloxypolysiloxane (hereinafter abbreviated as alkenyloxypolysiloxane I) shown below were added, and mixed and stirred for 15 minutes under the condition of exclusion of moisture to prepare an RTV siloxane composition.

Next, this composition was extruded into a sheet having a thickness of 2 mm,
When exposed to air at 55 ° C and 55% RH, this product was touch-dried for 5 minutes, and the physical properties of the cured product obtained by leaving this product in the same atmosphere for 7 days are as shown in Table 1. Then, the physical properties of the sheet with a thickness of 2 mm, which was made by putting this material in a sealed container and leaving it at 70 ° C for 7 days and leaving it at 23 ° C for 6 months, are as shown in Table 1. From this result, it was confirmed that this product has excellent storage stability.

Examples 2-6, Comparative Examples 1-2 The amount of alkoxysilane, guanidyl group-containing silane, organotin compound and formula shown in Table 2 was added to 100 parts of the base compound prepared in Example 1. A siloxane represented by (hereinafter abbreviated as alkenyloxypolysiloxane II), a formula A siloxane represented by (hereinafter abbreviated as alkenyloxypolysiloxane III), or a formula Siloxane (hereinafter abbreviated as alkenyloxypolysiloxane IV) is added and blended, and treated in the same manner as in Example 1 to prepare 7 kinds of compositions. Thickness after storage for 6 months at ℃
When 2 mm sheets were prepared and cured at room temperature in an atmosphere of 23 ° C. and 55% RH, the physical properties of the sheets were examined, and the results as shown in Table 2 were obtained.

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Claims (1)

[Claims] 1. A) 100 parts by weight of a diorganopolysiloxane whose both molecular chain ends are blocked with a hydroxyl group or a di- or trialkoxy group, b) a filler of ^{1 to} 400 parts by weight, c) a general formula R ¹ mSi (OR ² ) _4- m (wherein R ¹ is a monovalent hydrocarbon group, R ² is an alkyl group or an alkoxy group-substituted alkyl group, m is 0 or 1) or an alkoxysilane or a partial hydrolyzate thereof 1 to 50 wt. Part, d) a silane or siloxane having at least one group represented by the general formula (R ³ ₂ N) ₂ C = N- (wherein R ³ is a hydrogen atom or a monovalent hydrocarbon group) in one molecule 0.01 to 10 parts by weight, e) 0.01 to 10 parts by weight of organic tin compound, f) General formula (Wherein R ¹ , R ² , and R ³ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, R ⁴ is a methyl group, vinyl group, methoxy group, A is oxygen (-0-) or -CH ₂ CH ₂ A group, a is 0 or 1,
b is composed of 0.1 to 10 parts by weight of an organopolysiloxane having at least one unit having an alkenyloxy group represented by 1, 2 or 3) in one molecule, and a room temperature curable organopolysiloxane composition. object.