JP2009040838A - Method for preparing room temperature-curable polyorganosiloxane composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain a room temperature-curable polyorganosiloxane composition at low cost, which has greatly improved curability and storage stability and is suitable for a sealing material, for example. <P>SOLUTION: In preparation of the room temperature-curable polyorganosiloxane composition containing 100 pts.wt. of polyorganosiloxane (A) that is represented by a specific structure including a hydrolysis group and has viscosity (23°C) of 20-1,000,000 mPa s, 0.1-20 pts.wt. of organosilane (B) represented by an average composition formula: R<SP>2</SP><SB>b</SB>Si(OR<SP>3</SP>)<SB>4-b</SB>, 1-500 pts.wt. of inorganic filler (C), and 0.01-10 pts.wt. of a curing catalyst (D), the component (C) is mixed with the component (A) alone or with a mixture prepared by blending a part or the whole of the component (B) with the component (A) after adding a hydrophilic solvent having a boiling point higher than that of water to the component (C) and heating this under reduced pressure for dehydration, and then the resultant is mixed with the component (D). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for preparing a room temperature curable polyorganosiloxane composition, and more particularly to a method for preparing a one-component room temperature curable polyorganosiloxane composition that cures at room temperature with moisture in the air.

  Conventionally, polyorganosiloxane compositions that are cured at room temperature upon contact with moisture in the air and become rubber elastic bodies have been used as sealing materials, industrial adhesives, potting materials, etc. in various fields such as architecture, machinery, and electricity. Widely used.

  The polyorganosiloxane composition used for such sealants and industrial adhesives has various safety-related properties such as self-extinguishing properties and heat resistance in accordance with safety demands such as electrical appliances in recent years. Further improvements in properties are desired. Therefore, in order to provide self-extinguishing properties in addition to reinforcing properties, inorganic fillers having a large amount of moisture absorption (adsorbed water) such as pulverized silica, titanium dioxide, zinc carbonate, and aluminum hydroxide are used.

When such an inorganic filler is added to a polyorganosiloxane composition that cures in contact with moisture, the curability and storage stability of the composition are lowered due to the influence of adsorbed water. Therefore, proposals have been made to use an inorganic filler whose surface has been previously hydrophobized with organosilazane, organocyclosiloxane, organochlorosilane, organoalkoxysilane, or the like (see, for example, Patent Document 1). In addition, after mixing the base polymer and the inorganic filler in advance under reduced pressure heating, the crosslinking agent and the curing catalyst are blended and mixed uniformly to prevent a decrease in curability and storage stability.
Japanese Patent Publication No. 5-88866

  However, even if an inorganic filler that has been surface-treated in advance is used, a sufficient effect cannot be obtained, and the material cost is further increased. Further, the method of heating the base polymer and the inorganic filler under reduced pressure has a problem that the dehydration effect by heating is not sufficient, and the curability and storage stability are poor.

  The present invention has been made in order to cope with such problems, and greatly improves curability and storage stability. For example, a room temperature curable polyorganosiloxane composition suitable for a sealing material and the like is inexpensive and easy. It is an object of the present invention to provide a preparation method that can be obtained.

  As a result of intensive investigations to achieve the above object, the present inventors have formulated a room temperature curable polyorganosiloxane composition by adding an inorganic filler that has been subjected to heat treatment by adding a hydrophilic solvent. The present inventors have found that a composition having greatly improved curability, storage stability, and the like can be obtained, and have led to the present invention.

（式中、Ｒ^１は置換または非置換の１価の炭化水素基、Ｘは加水分解性基、ａは０、１または２の整数、ｎは正の整数である。）で表され、２３℃における粘度が２０〜１，０００，０００ｍＰａ・ｓであるポリオルガノシロキサン１００重量部と、（Ｂ）平均組成式：Ｒ^２ _ｂＳｉ（ＯＲ^３）_４−ｂ（式中、Ｒ^２、Ｒ^３は互いに同一でも異なっていてもよい置換または非置換の１価の炭化水素基であり、ｂは０、１または２の整数である。）で表されるオルガノシランまたはその部分加水分解縮合物０．１〜２０重量部と、（Ｃ）粉砕シリカ、重質炭酸カルシウム、炭酸亜鉛、二酸化チタン、水酸化アルミニウムから選ばれる少なくとも１種の無機充填剤１〜５００重量部、および（Ｄ）硬化触媒０．０１〜１０重量部をそれぞれ含有する室温硬化性ポリオルガノシロキサン組成物を調製するにあたり、前記（Ｃ）成分に水より沸点の高い親水性溶剤を加え、６０ｃｍＨｇ以下の減圧下５０℃以上の温度で１時間以上加熱する加熱処理工程と、前記（Ａ）成分に、あるいは前記（Ａ）に前記（Ｂ）成分の一部または全量を配合した混合物に、前記加熱処理された（Ｃ）成分を配合する工程と、前記工程で得られた組成物に、前記（Ｂ）成分の全量あるいは残量と前記（Ｄ）成分を配合する工程とを備えることを特徴とする。 That is, the method for preparing the room temperature curable polyorganopolysiloxane composition of the present invention comprises (A) the general formula:

Where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, X is a hydrolyzable group, a is an integer of 0, 1 or 2, and n is a positive integer. 100 parts by weight of polyorganosiloxane having a viscosity at 20 ° C. of 20 to 1,000,000 mPa · s, and (B) average composition formula: R ² _b Si (OR ³ ) _4-b (wherein R ² , R ³ Is a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, b is an integer of 0, 1 or 2) or a partially hydrolyzed condensate thereof 0 1 to 20 parts by weight, (C) 1 to 500 parts by weight of at least one inorganic filler selected from pulverized silica, heavy calcium carbonate, zinc carbonate, titanium dioxide, and aluminum hydroxide, and (D) a curing catalyst Each containing 0.01 to 10 parts by weight In the preparation of the room temperature curable polyorganosiloxane composition to be heated, a hydrophilic solvent having a boiling point higher than that of water is added to the component (C), and the mixture is heated at a temperature of 50 ° C. or higher under a reduced pressure of 60 cmHg or lower for 1 hour or longer. And the step of blending the heat-treated component (C) with the component (A) or the mixture of the component (B) with a part or all of the component (B). A step of blending the total amount or remaining amount of the component (B) and the component (D) into the obtained composition is characterized.

  According to the present invention, in blending the inorganic filler as component (C) with the reactive polyorganosiloxane as component (A), a hydrophilic solvent having a boiling point higher than that of water is previously added to component (C) to reduce the pressure. By performing the heat treatment below, the amount of water contained in (C) the inorganic filler can be extremely reduced. Then, by blending the inorganic filler (C) dehydrated by this heat treatment into the component (A) alone or in a mixture in which part or all of the component (B) is blended with (A), A room temperature curable polyorganosiloxane composition having greatly improved curability and storage stability can be obtained.

  In addition, according to the preparation method of the present invention, (C) the time required for the heat treatment and dehydration of the inorganic filler can be shortened, and the inorganic filler can be condensed during and after the heat treatment. Can be suppressed. Therefore, the dispersibility of the inorganic filler is improved, and a composition free of condensate called “butsu” can be obtained. Furthermore, it is also effective in improving the flame retardancy of the composition. Furthermore, since moisture re-adsorption to the inorganic filler is prevented, a composition having stable curability is obtained, and the mechanical properties of the cured product are not deteriorated.

  Embodiments of the present invention will be described below.

  In the embodiment of the present invention, (A) 100 parts by weight of a polyorganosiloxane whose molecular chain end is blocked with a hydrolyzable group, and (B) an organosilane having a hydrolyzable group bonded to a silicon atom or its partial hydrolysis. A room temperature-curable polyorganosiloxane composition containing 0.1 to 20 parts by weight of a decomposition condensate, (C) 1 to 500 parts by weight of an inorganic filler, and (D) 0.01 to 10 parts by weight of a curing catalyst. It is a method of preparation.

The component (A) serves as a base polymer of the composition obtained by the present invention, and a polyorganosiloxane represented by the following general formula is used.

In the above general formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group. As a hydrocarbon group, a C1-C10 thing is preferable and a C1-C8 thing is especially preferable. Specifically, alkyl groups such as methyl, ethyl, propyl, butyl, and hexyl groups; aryl groups such as phenyl and tolyl groups; alkenyl groups such as vinyl, allyl, butenyl, and hexenyl groups; A cycloalkyl group such as a cyclohexyl group; an aralkyl group such as a benzyl group or a 2-phenylethyl group; or a group in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with a halogen atom, a cyano group, or the like; For example, chloromethyl group, trifluoropropyl group, cyanoethyl group and the like can be mentioned. A methyl group, a phenyl group, a vinyl group, and a trifluoropropyl group are preferable, and a methyl group is particularly preferable. a is an integer of 0, 1 or 2, with 0 or 1 being particularly preferred.

  X is a hydrolyzable group. As the hydrolyzable group X, alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, methoxyethoxy group; propenoxy group, isobutenyloxy group, 1-ethyl-2-methylvinyloxy group, etc. An alkenyloxy group; a ketoxime group such as a dimethylketoxime group, a methylethylketoxime group, a methylbutylketoxime group, a diethylketoxime group, a cyclopentanooxime group, a cyclohexanooxime group; an acetoxy group, a propionoxy group, a butyroyloxy group, a benzoyl group Acyloxy groups such as groups; N-methylamino group, N-ethylamino group, N-propylamino group, N-butylamino group, N, N-dimethylamino group, N, N-diethylamino group, cyclohexylamino group, etc. Amino group; N-methylacetate An amide group such as an amide group and an N-methylbenzamide group; an aminoxy group such as an N, N-dimethylaminoxy group and an N, N-diethylaminoxy group; an isocyanate group; an α-silyl ester group; a propylene glycol monomethyl ether group; And halogen atoms such as chlorine atoms. Among these, an alkoxy group, an alkenyloxy group, a ketoxime group, an acyloxy group, an α-silyl ester group, and a propylene glycol monomethyl ether group are preferable, and in particular, a methoxy group, an ethoxy group, a dimethyl ketoxime group, a methylethyl ketoxime group, a methyl group. A butyl ketoxime group, an α-silyl ester group, and a propylene glycol monomethyl ether group are preferred.

  In the above general formula, n is a number corresponding to the degree of polymerization, and the viscosity of component (A) at 23 ° C. is 20 to 1 due to ease of handling, fluidity of the composition, physical properties after curing, and the like. , 000,000 mPa · s, more preferably 100 to 200,000 mPa · s.

Examples of the component (A) represented by the above general formula include those having the following structural formula. R ¹ represents the above-described substituted or unsubstituted monovalent hydrocarbon group, and X represents the above-mentioned hydrolyzable group.

Specifically, the following can be mentioned as (A) component.

The component (B) used in the embodiment of the present invention has a function as a crosslinking agent for crosslinking the component (A) to give a network structure. As the component (B), an organosilane represented by an average composition formula: R ² _b Si (OR ³ ) _4-b or a partially hydrolyzed condensate thereof is used. In the formula, R ² and R ³ are substituted or unsubstituted monovalent hydrocarbon groups which may be the same or different from each other, and b is an integer of 0, 1 or 2.

R ² includes a monovalent hydrocarbon group such as methyl group, ethyl group, propyl group, butyl group, vinyl group and phenyl group, chloromethyl group, cyanoethyl group, 3,3,3-trifluoropropyl group, etc. And monovalent substituted hydrocarbon groups. Examples of R ³ include these substituted or unsubstituted monovalent hydrocarbon groups, and an alkyl group is preferable.

  Examples of the component (B) include methyltrimethoxysilane, vinyltrimethoxysilane, decyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, methyltri (ethoxymethoxy) silane, dimethyldimethoxysilane, dimethyldiethoxysilane, Examples include diphenyldimethoxysilane and tetramethoxysilane. A silane having a ketoximato group such as phenyltris (methylethylketoximato) silane can also be used.

  In the embodiment of the present invention, at least a part (part or whole amount) of the component (B) is previously blended with the component (A) and mixed in the first blending step, or at least one of the component (B). At the same time, the heat-treated (C) inorganic filler, which will be described later, is blended, and then in the second blending step, the curing catalyst (D) and the remaining component (B) are mixed. The amount can be blended. In addition, when the whole quantity of (B) component is mix | blended at the 1st mixing | blending process, of course, (B) component is not mix | blended in a 2nd mixing | blending process. Moreover, the alkoxysilane of (B) component mix | blended with (A) component at a 1st mixing | blending process, and the alkoxysilane of (B) component mix | blended with a (D) hardening catalyst at a 2nd mixing | blending process, The same type or different types may be used.

  Furthermore, in the first blending step, the component (B) is not blended, and the entire amount may be blended in the second blending step, but at least a part of the component (B) is blended in the first blending step. Thus, a composition with better characteristics can be obtained.

  The component (B) blended with the component (A) in the first blending step reacts with the adsorbed moisture contained in the inorganic filler that is the component (C) blended thereafter, so the adsorbed water is (A). It works to eliminate the effect on ingredients. Therefore, it is preferable to blend the component (B) (alkoxysilane) in an amount sufficient to desorb / remove the adsorbed water contained in the inorganic filler (C) in the first blending step. The alkoxysilane which is the component (B) blended in the first blending step is the same as the component (A) in the same manner as the alkoxysilane of the component (B) blended with the (D) curing catalyst in the second blending step. Functions as a crosslinking agent.

  From the viewpoint of use as a crosslinking agent, trialkoxysilanes are preferably used, and dialkoxysilanes are particularly preferred when it is desired to lower the modulus of the cured product.

  (B) The compounding quantity of a component shall be 0.1-20 weight part with respect to 100 weight part of said (A) component. If it is less than 0.1 part by weight, a cured product having excellent mechanical properties cannot be obtained, and if it exceeds 20 parts by weight, the resulting cured product becomes brittle.

  The inorganic filler of component (C) used in the embodiment of the present invention is a reinforcing filler that gives mechanical strength to the rubber elastic body after curing. It is desirable to use one having an average particle size in the range of 0.1 to 50 μm, more preferably 0.1 to 30 μm. Examples of such inorganic fillers include pulverized silica, heavy calcium carbonate, zinc carbonate, titanium dioxide, and aluminum hydroxide. Since such inorganic fillers may be able to obtain sufficient durability by combination, one kind may be used alone, or a plurality kinds may be used in combination.

  In the embodiment of the present invention, before blending with the component (A), a hydrophilic solvent having a boiling point higher than that of water is added to the inorganic filler as the component (C), and dehydration is performed by heating in a reduced pressure state. . The water content of the inorganic filler (C) after the heat treatment is preferably 0.2% by weight or less as a heat loss value under the condition of 105 ° C. for 3 hours.

  Examples of the hydrophilic solvent having a boiling point higher than that of water include ethylene glycol and propylene glycol. By removing these hydrophilic solvents azeotropically with the water adsorbed on the inorganic filler (C), the time required for the heat dehydration treatment can be shortened. Moreover, by adding the said hydrophilic solvent and performing a heat | fever dehydration process, aggregation of an inorganic filler can be prevented and moisture re-adsorption can be suppressed. Furthermore, since ethylene glycol and propylene glycol have low flammability, handling is easy and there is little risk of fire.

  The heat dehydration treatment is performed by heating at a temperature of 50 to 200 ° C. for 1 to 6 hours under a reduced pressure of 60 cmHg or less, more preferably 30 cmHg or less.

  Component (C) is blended in an amount of 1 to 500 parts by weight, more preferably 5 to 300 parts by weight per 100 parts by weight of component (A). When the amount of component (C) is less than 1 part by weight, the resulting cured product has insufficient mechanical strength. Moreover, when it exceeds 500 weight part, mixing will become difficult. Moreover, since the discharge property of a composition and the workability | operativity which arranges a shape with a spatula in the case of construction of a composition worsen, it is unpreferable.

  The curing catalyst of the component (D) used in the embodiment of the present invention is a catalyst that promotes the condensation reaction between the components (A) and between the components (A) and (B).

  Such (D) curing catalysts include iron octoate, cobalt octoate, manganese octoate, zinc octoate, tin naphthenate, tin caprylate, tin oleate; dibutyltin diacetate, dibutyltin dioctoate, dibutyltin. Organotin compounds such as dilaurate, dibutyltin oleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate; tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate , Tetra (isopropenyloxy) titanate, diisopropoxybis (ethyl acetoacetate) titanium, diisopropoxybis (acetate) Methyl) titanium acetate, diisopropoxy bis (Asher acetone) titanium, dibutoxybis (ethyl acetoacetate) titanium, organic titanium compounds such as dimethoxy bis (ethyl acetoacetate) titanium; alkoxy aluminum compounds, and the like are exemplified. Of these, organotin compounds and organotitanium compounds are more preferred from the viewpoint of obtaining sufficient curability even in a small amount and the characteristics of the resulting composition.

  (D) The compounding quantity of a component shall be 0.01-10 weight part with respect to 100 weight part of said (A) component, More preferably, it shall be the range of 0.1-10 weight part. (D) When the blending amount of the curing catalyst exceeds 10 parts by weight, not only the curing becomes too fast, but discoloration such as yellowing of the cured product occurs, and the mechanical properties are adversely affected.

  The room temperature-curable polyorganosiloxane composition according to the embodiment of the present invention includes the components (A) to (D) as basic components, and, as necessary, known viscosity modifiers, plasticizers, pigments, You may mix | blend a heat resistance improver, a flame retardance imparting agent, an antifungal agent, an adhesion imparting agent, etc. in the range which does not impair the effect of this invention.

  In the embodiment of the present invention, the basic components (A) to (D) and the optional components described above are blended and mixed as shown below in a state where moisture is cut off.

  First, at least one selected from (C) pulverized silica, heavy calcium carbonate, zinc carbonate, titanium dioxide, and aluminum hydroxide having a heating loss at 105 ° C. for 3 hours of 0.3 to 0.5% by weight or more. The inorganic filler is charged into a mixer, kneader, etc. together with a hydrophilic solvent having a boiling point higher than that of water such as ethylene glycol and propylene glycol, and heated at 50 to 200 ° C. for 1 to 6 hours in a reduced pressure state of 60 cmHg or less, preferably 30 cmHg or less. Stir. By such heat treatment under reduced pressure, the value of the weight loss on heating, which is a measure of the amount of crystallization water and adsorbed water contained in component (C), is reduced to 0.2% by weight or less, more preferably 0.1% by weight or less. can do.

  Next, (C) the inorganic filler subjected to the heat treatment, the (A) component polyorganosiloxane alone or the (A) component polyorganosiloxane is added with at least a part of the (B) component crosslinking agent. Mix the mixture and mix uniformly. Thereafter, the mixture may be heated and stirred at a temperature of 50 to 200 ° C. under a reduced pressure of 60 cmHg or less, preferably 30 cmHg or less for 1 to 6 hours. By such heating and stirring, a composition having even more excellent storage stability can be obtained.

  It should be noted that, instead of mixing the mixture (A) with at least a part of the component (B) in advance with the component (C), the component (A) is blended with the component (C) and at the same time the component (B) At least a part can be blended.

  Next, the remainder of the component (B) is added as a crosslinking agent to the mixture, and the curing catalyst as the component (D) and the optional components described above are blended and mixed so as to be uniform.

  Thus, first, the inorganic filler as the component (C) is heated and dehydrated, and then the inorganic filler is premixed with a mixture of the component (A) and the component (B), or the component (C). At the same time or by blending the component (B) after blending the component (C) with the component (A), the deterioration of the component (A) is reduced, and the effect of heat dehydrating the inorganic filler is improved. Can do. A room temperature-curable polyorganosiloxane composition having excellent curability and storage stability can be obtained.

  In the case where the inorganic filler as component (C) is surface-treated with an organic substance such as fatty acid, fatty acid ester, or organosilane (for example, colloidal calcium carbonate), there is a concern about the alteration of the surface treatment agent. Heat treatment cannot be performed. When such an inorganic filler (C) is used, it is blended in a mixture of the component (A) and the component (B) as they are without performing a heat dehydration treatment, and mixed so as to be uniform. Thereafter, since a composition having more excellent storage stability can be obtained, the mixture may be heated and stirred at a temperature of 50 to 200 ° C. for 1 to 6 hours under a reduced pressure of 60 cmHg or less, preferably 30 cmHg or less.

  Next, the remainder of the component (B) is added as a crosslinking agent to the mixture, and the curing catalyst as the component (D) and the optional components described above are blended and mixed so as to be uniform. Thus, deterioration of the component (A) can be reduced, and a room temperature curable polyorganosiloxane composition excellent in curability and storage stability can be obtained.

  In the preparation method of the present invention, after at least a part of the component (B) is mixed with the component (A) in advance, the component (C) is mixed with the mixture, or the component (C) is added to the component (A). The reason why the curability and storage stability can be greatly improved by blending at least a part of the component (B) at the same time when blended and mixed is as follows.

  That is, when the inorganic filler as the component (C) contains a large amount of crystal water or adsorbed water, the composition obtained is extremely poor in storage stability if it is used as it is. Not only does the material increase in viscosity during storage, it is cured inside, or the curing becomes insufficient, and sufficient mechanical properties cannot be obtained, and it does not become rubbery. Therefore, it is necessary to heat the component (C) in advance under reduced pressure to sufficiently remove moisture.

  After removing moisture by heating under reduced pressure in this way, if the component (C) is sufficiently cooled (for example, 40 ° C. or lower) and then blended with the component (A), the influence of the heat treatment is small, A composition having the desired properties and storage stability is obtained. However, when the cooling of the component (C) is insufficient, the hydrolyzable group of the component (A) is deteriorated (hydrolysis due to residual water or condensed water), and the curability and mechanical properties of the composition are caused. Problems such as lowering. Further, even when the component (C) is sufficiently cooled after the heat treatment, moisture is adsorbed again due to the influence of condensed water or the like due to cooling, and this adsorbed water may cause deterioration of the component (A). Furthermore, there are problems such as economical loss of the heat source and the extension of process time due to cooling immediately after heating.

  In an embodiment of the present invention, the inorganic filler which is the component (C) is heat-treated with the hydrophilic solvent and dehydrated, and then the inorganic filler is premixed with the component (B) in the component (A). Or (B) component is blended with component (A) and the inorganic filler (C) component is blended at the same time, so the effect of adsorbed water contained in (C) inorganic filler is (B) Only hydrolysis occurs in a part of the component. Therefore, deterioration of the hydrolyzable group of the component (A) can be prevented. Further, even when the cooling of the component (C) is insufficient, the cooling is promoted by the heat of vaporization when the component (B) is vaporized, so that the deterioration of the component (A) is prevented.

  Furthermore, when the inorganic filler that is the component (C) is surface-treated with an organic substance, when the component (C) is blended with the component (A) alone, free matter generated from the organic substance that is the surface treatment agent, etc. Reacts with the hydrolyzable group of component (A) or causes an exchange reaction, resulting in a decrease in curability. In addition, the free organic substance reacts with the curing catalyst which is the component (D) to cause problems such as a reduction in catalytic activity. However, the inorganic filler surface-treated with an organic substance is blended in advance in a mixture in which the component (B) is blended with the component (A), or by blending the component (B) with the component (A) at the same time. Since the organic substance liberated from the surface treatment agent can be captured by the hydrolyzable group of the component (B), it is possible to prevent a decrease in curability and a decrease in catalyst activity.

  The room temperature-curable polyorganosiloxane composition obtained by the preparation method of the present invention can be suitably used, for example, as an adhesive or a coating material in the electric / electronic industry or as a building sealing material.

  EXAMPLES The present invention will be described in detail by examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, unless otherwise specified, “part” means “part by weight” and “%” means “part by weight”. The physical properties such as viscosity are values at 23 ° C. and relative humidity (RH) 50%.

Example 1
In the mixer where the moisture was cut off, the heat loss at 105 ° C. for 3 hours was 0.5%, 150 parts of pulverized silica having an average particle size of 4.0 μm, and the heat loss at 105 ° C. for 3 hours was 0.5%, 30 parts of titanium dioxide having an average particle diameter of 0.15 μm and 1 part of ethylene glycol were added, and the mixture was heated and stirred at 30 cmHg and 130 ° C. for 2 hours. About the grinding | pulverized silica and titanium dioxide after this heat processing, the heat loss of 105 degreeC-3 hours was measured. Further, the water content was measured by the Karl Fischer method.

  Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was charged into the mixer and mixed until uniform (first blending step). The temperature of the mixture at this time was 88 degreeC. Thereafter, 1 part of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Example 2
The same pulverized silica and titanium dioxide as in Example 1 were similarly heat-treated, and the heat loss and moisture content at 105 ° C. for 3 hours were measured for the pulverized silica and titanium dioxide after the heat treatment. Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was added to this mixer and mixed with 2 parts of methyltrimethoxysilane and mixed until uniform (No. 1). 1 blending step).
Thereafter, 1 part of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Example 3
After the same pulverized silica and titanium dioxide as in Example 2 were heat-treated in the same manner, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was added to this mixer as in Example 2. A mixture of 2 parts of methyltrimethoxysilane was added to and mixed until uniform (first blending step).

  Subsequently, it heat-mixed at 110 degreeC under 30 cmHg pressure reduction for 1 hour. Thereafter, 1 part of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Example 4
In the mixer where the moisture was cut off, the heating loss at 105 ° C. for 3 hours was 0.3%, 30 parts of pulverized silica having an average particle size of 1.5 μm, and the heating loss at 105 ° C. for 3 hours was 0.4%, 10 parts of zinc carbonate having an average particle diameter of 4.5 μm was added together with 1 part of propylene glycol, and the mixture was heated and stirred at 30 cmHg and 130 ° C. for 2 hours. About the grinding | pulverized silica and zinc carbonate after this heat processing, the heat loss of 105 degreeC-3 hours was measured. Further, the water content was measured by the Karl Fischer method.

  Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was added to this mixer, and 3 parts of methyltrimethoxysilane was added and mixed until uniform (No. 1). 1 blending step). Thereafter, 2 parts of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step) and mixed uniformly under moisture blocking. As a result, a polyorganosiloxane composition was obtained.

Example 5
In the mixer where the moisture was cut off, the heating loss at 105 ° C. for 3 hours was 0.3%, 30 parts of pulverized silica having an average particle size of 1.5 μm, and the heating loss at 105 ° C. for 3 hours was 0.4%, 10 parts of zinc carbonate having an average particle size of 4.5 μm was added together with 1 part of propylene glycol, and heated and stirred at 30 cmHg and 120 ° C. for 2 hours. About the grinding | pulverized silica and zinc carbonate after this heat processing, the heating loss and water content for 105 degreeC-3 hours were measured, respectively.

  Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was added to this mixer, and 3 parts of methyltrimethoxysilane was added and mixed until uniform (No. 1). 1 mixing step), the mixture was heated and mixed at 110 ° C. for 1 hour under a reduced pressure of 30 cmHg. Thereafter, 2 parts of methyltrimethoxysilane and 2.5 parts of diisopropoxytitanium bis (ethylacetylacetate) were blended (second blending step), and mixed uniformly under a moisture blockage to obtain a polyorganosiloxane composition. Obtained.

Comparative Example 1
In the mixer where the moisture was cut off, the heat loss at 105 ° C. for 3 hours was 0.5%, 150 parts of pulverized silica having an average particle size of 4.0 μm, and the heat loss at 105 ° C. for 3 hours was 0.5%, 30 parts of titanium dioxide having an average particle size of 0.15 μm was added, and the mixture was heated and stirred at 30 cmHg and 130 ° C. for 3 hours. About the grinding | pulverized silica and titanium dioxide after this heat processing, the heat loss of 105 degreeC-3 hours was measured. Further, the water content was measured by the Karl Fischer method.

  Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was charged into the mixer and mixed until uniform (first blending step). Thereafter, 3 parts of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Comparative Example 2
In the mixer where the moisture was cut off, the heat loss at 105 ° C. for 3 hours was 0.5%, 150 parts of pulverized silica having an average particle size of 4.0 μm, and the heat loss at 105 ° C. for 3 hours was 0.5%, After adding 30 parts of titanium dioxide having an average particle size of 0.15 μm, 2 parts of methyltrimethoxysilane was mixed with 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s. (First blending step) The materials were charged and mixed until uniform. Thereafter, 1 part of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Comparative Example 3
In the mixer where the moisture was cut off, the heat loss at 105 ° C. for 3 hours was 0.5%, 150 parts of pulverized silica having an average particle size of 4.0 μm, and the heat loss at 105 ° C. for 3 hours was 0.5%, After adding 30 parts of titanium dioxide having an average particle size of 0.15 μm, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was added thereto and mixed until uniform. (First blending step). Thereafter, 3 parts of methyltrimethoxysilane, 2 parts of N-trimethylsilyl-3-aminopropyltrimethoxysilane, and 0.5 part of dibutyltin dilaurate were blended (second blending step), and mixed uniformly while blocking moisture. A polyorganosiloxane composition was obtained.

Comparative Example 4
In the mixer where the moisture was cut off, the heating loss at 105 ° C. for 3 hours was 0.3%, 30 parts of pulverized silica having an average particle size of 1.5 μm, and the heating loss at 105 ° C. for 3 hours was 0.4%, 10 parts of zinc carbonate having an average particle diameter of 4.5 μm was added, and the mixture was heated and stirred at 30 cmHg and 120 ° C. for 3 hours. About the grinding | pulverized silica and zinc carbonate after heat processing, the heating loss and water content for 105 degreeC-3 hours were measured, respectively.

  Next, 100 parts of α, ω-bis (methyldimethoxysiloxy) polydimethylsiloxane having a viscosity of 15 Pa · s was charged into the mixer and mixed until uniform (first blending step). Thereafter, 5 parts of methyltrimethoxysilane and 2.5 parts of diisopropoxytitanium bis (ethylacetylacetate) were blended (second blending step), and mixed uniformly while blocking moisture, to obtain a polyorganosiloxane composition. Obtained.

Example 6
120% titanium dioxide with an average particle size of 0.15 μm and 1 part ethylene glycol and 1 part ethylene glycol are added to a mixer where the moisture is cut off for 0.5 hours at 105 ° C. for 3 hours and 2 parts at 130 ° C. for 2 hours. Stir with heating. About the titanium dioxide after heat processing, the heat loss of 105 degreeC-3 hours was measured. Further, the water content was measured by the Karl Fischer method.

  Next, 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 40 Pa · s was charged into the mixer and mixed until uniform (first blending step). Thereafter, 5 parts of phenyltris (methylethylketoximato) silane and 0.1 part of dibutyltin dilaurate were respectively blended (second blending step) and uniformly mixed under moisture shielding to obtain a polyorganosiloxane composition.

Example 7
The same titanium dioxide as in Example 6 was similarly heat-treated, and the heat loss and water content at 105 ° C. for 3 hours were measured for the titanium dioxide after the heat treatment. Next, 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 40 Pa · s was mixed with 3 parts of phenyltris (methylethylketoximato) silane, and mixed until uniform (1st Compounding step).

  Thereafter, 5 parts of phenyltris (methylethylketoximato) silane and 0.1 part of dibutyltin dilaurate were respectively blended (second blending step) and uniformly mixed under moisture shielding to obtain a polyorganosiloxane composition.

Example 8
120 parts of zinc carbonate with a heat loss of 105% at 105 ° C. for 3 hours and an average particle size of 4.5 μm together with 1 part of ethylene glycol is added to a mixer where moisture has been cut off, together with 1 part of ethylene glycol, at 30 cmHg and 120 ° C. for 2 hours. Stir with heating. About the zinc carbonate after heat processing, the heat loss and water content of 105 degreeC-3 hours were measured, respectively.

  Next, 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 40 Pa · s was mixed with 3 parts of phenyltris (methylethylketoximato) silane, and mixed until uniform (first 1 After that, the mixture was further heated and mixed at 110 ° C. for 1 hour under a reduced pressure of 30 cmHg.

  Thereafter, 5 parts of phenyltris (methylethylketoximato) silane and 0.1 part of dibutyltin dilaurate were respectively blended (second blending step) and uniformly mixed under moisture shielding to obtain a polyorganosiloxane composition.

Example 9
120 parts of titanium dioxide having a heat loss of 105% at 105 ° C. for 3 hours and an average particle size of 0.15 μm together with 1 part of propylene glycol is added to a mixer where moisture has been cut off, and then at 30 cmHg and 130 ° C. for 2 hours. Stir with heating. About the titanium dioxide after heat processing, the heating loss and water content of 105 degreeC-3 hours were measured, respectively.

  Next, 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 40 Pa · s was mixed with 3 parts of phenyltris (methylethylketoximato) silane, and mixed until uniform (first 1 After that, the mixture was further heated and mixed at 110 ° C. for 1 hour under a reduced pressure of 30 cmHg.

  Thereafter, 5 parts of phenyltris (methylethylketoximato) silane and 0.1 part of dibutyltin dilaurate were respectively blended (second blending step) and uniformly mixed under moisture shielding to obtain a polyorganosiloxane composition.

Comparative Example 5
120 parts of titanium dioxide having a weight loss of 105% at 105 ° C. for 3 hours and an average particle size of 0.15 μm was added to the mixer where moisture was cut off, and the mixture was heated and stirred at 30 cmHg and 130 ° C. for 3 hours. About the titanium dioxide after heat processing, the heating loss and water content of 105 degreeC-3 hours were measured, respectively.

  Next, 100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 40 Pa · s was mixed with 3 parts of phenyltris (methylethylketoximato) silane, and mixed until uniform (first 1 After that, the mixture was further heated and mixed at 110 ° C. for 1 hour under a reduced pressure of 30 cmHg.

  Thereafter, 5 parts of phenyltris (methylethylketoximato) silane and 0.1 part of dibutyltin dilaurate were respectively blended (second blending step) and uniformly mixed under moisture shielding to obtain a polyorganosiloxane composition.

  Next, the compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 5 were evaluated as shown below. The results are shown in Tables 1 and 2.

[Tack Free Time]
After extruding the composition into an atmosphere of 23 ° C. and 50% RH, the time taken to contact the surface of the extrudate with a finger and confirm that it was dry was measured.

[Physical properties]
The composition was extruded into a sheet molding die and allowed to cure for 7 days under conditions of a temperature of 23 ° C. and a humidity of 50% to prepare a sheet having a thickness of 2 mm. The physical properties of this sheet were measured according to JIS K 6249.

[Storage stability]
The composition was put in a container where moisture was cut off, heated at 70 ° C. for 168 hours, and then tack-free time was measured in an atmosphere of 23 ° C. and 50% RH. Then, it adjusted so that it might become a sheet | seat of thickness 2mm, it was left to stand for 7 days, and it hardened | cured with the humidity in the air, and measured the physical characteristic of hardened | cured material based on JISK6249.

  As is clear from Table 1, the polyorganosiloxane compositions obtained in Examples 1 to 9 are more curable and storage stable than the polyorganosiloxane compositions obtained in Comparative Examples 1 to 5. Greatly improved.

  Moreover, by adding a hydrophilic solvent such as ethylene glycol or propylene glycol to the inorganic filler which is the component (C) and performing the heat treatment, the time required for the treatment can be shortened, and the inorganic filler It was found that the dispersibility of the composition was improved, and a composition having no condensate (bups) could be obtained.

Claims (4)

(A) General formula:

Where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, X is a hydrolyzable group, a is an integer of 0, 1 or 2, and n is a positive integer. 100 parts by weight of a polyorganosiloxane having a viscosity at 20 ° C. of 20 to 1,000,000 mPa · s,
(B) Average composition formula: R ² _b Si (OR ³ ) _4-b
Wherein R ² and R ³ are substituted or unsubstituted monovalent hydrocarbon groups which may be the same or different from each other, and b is an integer of 0, 1 or 2. 0.1-20 parts by weight of silane or its partial hydrolysis condensate,
(C) 1 to 500 parts by weight of at least one inorganic filler selected from pulverized silica, heavy calcium carbonate, zinc carbonate, titanium dioxide, and aluminum hydroxide, and (D) 0.01 to 10 parts by weight of a curing catalyst. In preparing each room temperature curable polyorganosiloxane composition,
A heat treatment step of adding a hydrophilic solvent having a boiling point higher than that of water to the component (C) and heating at a temperature of 50 ° C. or higher under a reduced pressure of 60 cmHg or lower for 1 hour or longer;
Blending the heat-treated component (C) with the component (A) or a mixture of the component (A) with a part or all of the component (B);
A method for preparing a room temperature-curable polyorganosiloxane composition, comprising: adding the total amount or remaining amount of the component (B) and the component (D) to the composition obtained in the step.   2. The method for preparing a room temperature-curable polyorganosiloxane composition according to claim 1, wherein the component (C) has an average particle size of 0.1 to 50 [mu] m.   3. The room temperature-curable polyorganosiloxane composition according to claim 1, wherein in the heat treatment step, the heat loss of the component (C) at 105 ° C. for 3 hours is reduced to 0.2 wt% or less. Preparation method.   After mixing and mixing said (C) component with said (A) component, it has the process of heating these mixtures at the temperature of 50-200 degreeC under reduced pressure of 60 cmHg or less for 1 to 6 hours, It is characterized by the above-mentioned. Item 4. A method for preparing a room temperature-curable polyorganosiloxane composition according to any one of Items 1 to 3.