Method for producing room-temperature curable organopolysiloxane composition

Abstract

To provide a method for inexpensively producing a room temperature-curable organopolysiloxane composition having excellent storage stability, heat resistance and weather resistance (discoloration resistance), ultraviolet resistance or the like by using, as a starting raw material, an organopolysiloxane having a terminal silanol group as the main agent.SOLUTION: There is provided a method for producing a room temperature-curable organopolysiloxane composition which comprises a specific amount of (A) an organopolysiloxane with both terminals of the molecular chain blocked with silanol groups, (B) a condensation catalyst composed of a mixture of carboxylic acid and a metal salt of the same or different carboxylic acid, (C) a hydrolyzable organosilane compound and / or a partial hydrolysis condensate, and (D) a filler, wherein the method comprises: [i] a step of mixing (A) and a part or all of (C) in the presence of (B) to block the silanol groups in (A) with hydrolyzable silyl groups; and [ii] a step of mixing a remainder of (C) and (D) in a reaction mixture obtained in [i].SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for inexpensively producing a room temperature curable organopolysiloxane composition having excellent storage stability, heat and weather resistance (discoloration resistance), ultraviolet resistance, etc., using an organopolysiloxane having a terminal silanol group as a starting material (base polymer).

Background Art

[0002] Room temperature curable silicone rubber compositions that crosslink by moisture are easy to handle and have excellent weather resistance and electrical properties, so they are used in various fields such as sealing materials for building materials and adhesives in the electrical and electronic fields. Many of these room temperature curable silicone rubber compositions are designed using organopolysiloxanes having silanol groups at their terminals as starting materials, and tin catalysts were frequently used from the viewpoint of reactivity. However, in recent years, there are concerns about toxicity to the human body and the environment, and environmental regulations have become stricter, so their use is being shunned.

[0003] Titanium catalysts, which are considered as alternatives to tin catalysts, have high reactivity and are difficult to adjust because they gel when using organopolysiloxanes having silanol groups at their terminals as raw materials. By using organopolysiloxanes that are end-capped with alkoxysilyl groups in advance, such problems can be avoided, but there are drawbacks such as increased costs.

[0004] As a solution to the above problems, by using a specific amino group-containing silane as an end-capping catalyst, it is possible to block the silanol group terminals during the production process and obtain a room temperature curable organopolysiloxane composition having excellent storage stability. However, when an amino group-containing silane is used as an end-capping catalyst, the cured product of the organopolysiloxane may discolor when exposed to high temperature conditions or ultraviolet rays after curing. In addition, the following documents are cited as prior arts related to the present invention.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 63-83166 [Patent Document 2] Japanese Patent Publication No. 7-39547 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] The present invention has been made in view of the above circumstances, and during the production process of a room-temperature curable organopolysiloxane composition, the terminal silanol groups of a molecular chain both-end silanol group-blocked organopolysiloxane as a main agent (base polymer) can be inexpensively blocked with hydrolyzable silyl groups, and it does not discolor even when exposed to high-temperature conditions or ultraviolet rays after curing. An object of the present invention is to provide an inexpensive production method for a room-temperature curable organopolysiloxane composition. [Means for Solving the Problems]

[0007] As a result of intensive studies to solve the above problems, the present inventors used a mixture obtained by previously uniformly mixing a metal carboxylate and a carboxylic acid as a condensation catalyst, and in the presence of the condensation catalyst, a molecular chain both-end silanol group-blocked organopolysiloxane as a main agent (base polymer), By mixing with a hydrolyzable organosilane compound and / or its partial hydrolysis condensate, the terminal silanol groups of the base polymer are blocked with hydrolyzable silyl groups during the production of the composition, so that a room-temperature curable organopolysiloxane composition excellent in storage stability can be obtained inexpensively. The present invention was completed based on the finding that the cured product of the room-temperature curable organopolysiloxane composition produced through this process does not discolor even when exposed to high-temperature conditions or ultraviolet rays.

[0008] Therefore, the present invention provides a method for producing the following room-temperature curable organopolysiloxane composition. [1] A method for producing a room-temperature curable organopolysiloxane composition, comprising the following components (A) to (D): (A) Organopolysiloxane having silanol groups blocked at both ends of the molecular chain: 100 parts by mass, (B) A condensation catalyst comprising a mixture of a carboxylic acid and a metal salt of the same or different carboxylic acid as the carboxylic acid, wherein the mixing ratio of the carboxylic acid and the metal carboxylate is 1:99 to 50:50 by mass ratio of the metal carboxylate to the carboxylic acid: 0.01 to 30 parts by mass, (C) Hydrolyzable organosilane compound and / or its partial hydrolysis condensate (However, except for the case where the number of hydrolyzable groups bonded to the silicon atom in the molecule is 1.) : 0.1 to 30 parts by mass, and (D) Filler: 1 to 1,000 parts by mass, [i] A step of mixing component (A) with part or all of component (C) in the presence of component (B) to block the silanol groups at both ends of the molecular chain of the organopolysiloxane of component (A) with hydrolyzable silyl groups, and then, [ii] A step of mixing the remaining part of component (C) and component (D) with the reaction mixture obtained by mixing and reacting part or all of components (A), (B) and (C) obtained in step [i]. A method for producing a room-temperature curable organopolysiloxane composition, characterized by comprising the above steps. [2] In step [ii], further, (E) A curing catalyst other than component (B): 0.001 to 15 parts by mass based on 100 parts by mass of component (A), and (F) Adhesion promoter: 0.1 to 30 parts by mass based on 100 parts by mass of component (A) The method for producing a room-temperature curable organopolysiloxane composition according to [1], wherein at least one selected from the above is mixed. [3] After step [i], the method for producing a room-temperature curable organopolysiloxane composition according to [1] or [2], comprising a step of adding a basic substance to the reaction mixture obtained by mixing and reacting part or all of components (A), (B) and (C) to neutralize the reaction mixture. [Advantages of the Invention]

[0009] By the production method of the present invention, a room temperature curable organopolysiloxane composition using a molecular chain both ends hydrolyzable silyl group-blocked base polymer prepared during the production process using a specific mixed catalyst does not discolor even when exposed to high temperature conditions or ultraviolet rays (UV) after curing.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0011] In the production method of the room temperature curable organopolysiloxane composition of the present invention, the component (A) used as the base polymer of the room temperature curable organopolysiloxane composition is an organopolysiloxane (main agent) in which both ends of the molecular chain are blocked with silanol groups (hydroxyl groups bonded to silicon atoms).

[0012] As the organopolysiloxane of the component (A), specifically, a linear diorganopolysiloxane in which both ends of the molecular chain are blocked with silanol groups represented by the following formula (1) is preferably mentioned.

Chemical formula

[0013] The viscosity at 23°C of the diorganopolysiloxane represented by the above formula (1) is preferably 100 to 1,000,000 mPa·s, particularly 300 to 100,000 mPa·s.

[0014] Note that the viscosity is a value measured by a rotational viscometer (e.g., BL type, BH type, BS type, cone plate type, etc.) (hereinafter the same). Further, the repeating number (m) or degree of polymerization of the diorganosiloxane unit in the diorganopolysiloxane represented by the above formula (1) is determined as the number average degree of polymerization (or number average molecular weight) in terms of polystyrene in gel permeation chromatography (GPC) analysis using toluene or the like as a developing solvent.

[0015] In the above formula (1), examples of the unsubstituted or substituted alkyl group having 1 to 12 carbon atoms or the unsubstituted or substituted aryl group having 6 to 10 carbon atoms for R include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, etc.; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, etc.; aryl groups such as phenyl group, tolyl group, xylyl group, α-, β-naphthyl group, etc.; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as F, Cl, Br, etc. or cyano groups, etc., for example, 3-chloropropyl group, 3,3,3-trifluoropropyl group, 2-cyanoethyl group, etc. Among these, alkyl groups such as methyl group and ethyl group are preferred, and methyl group is particularly preferred.

[0016] In the above formula (1), Y is an oxygen atom or a divalent hydrocarbon group having 1 to 8 carbon atoms, and -(CH 2 CH 2 ) q -, or -(CH=CH) q -(where q represents 1 to 4) is preferred. Among these, an oxygen atom, -CH 2 CH 2 -, or -CH=CH- is particularly preferred.

[0017] Examples of the structure of the linear organopolysiloxane represented by the above formula (1) include organopolysiloxanes having silanol groups blocking both ends of the molecular chain, organopolysiloxanes having diorganohydroxysilylethyl groups blocking both ends of the molecular chain, organopolysiloxanes having diorganohydroxysilylpropyl groups blocking both ends of the molecular chain, and the like.

[0018] The organopolysiloxane having silanol groups blocking both ends of the molecular chain of component (A) may be used alone or in combination of two or more having different structures and degrees of polymerization.

[0019] (B) component In the method for producing the room-temperature curable organopolysiloxane composition of the present invention, the room-temperature curable organopolysiloxane composition contains, as component (B), a condensation catalyst (pre-mixed catalyst) comprising a mixture obtained by previously and uniformly mixing a carboxylic acid and a metal salt of the same or different carboxylic acid as the carboxylic acid. The carboxylic acid and the metal carboxylate in the condensation catalyst are each prepared as a previously and uniformly mixed mixture (condensation catalyst) before being individually mixed with other components in the composition when being blended into the room-temperature curable organopolysiloxane composition, and function as a highly active condensation catalyst by being blended into the room-temperature curable organopolysiloxane composition in the form of the homogeneous mixture (condensation catalyst). When the carboxylic acid and the metal carboxylate are each blended into the room-temperature curable organopolysiloxane composition alone (as individual components), the function as a catalyst is significantly impaired, and thus a cured product (silicone rubber cured product) excellent in mechanical strength and high extensibility cannot be obtained.

[0020] (B) The condensation catalyst consists of a condensation catalyst composed of a mixture obtained by previously and uniformly mixing a carboxylic acid and a metal salt of a carboxylic acid that is the same as or different from the carboxylic acid (particularly, a condensation catalyst consisting only of a mixture obtained by previously and uniformly mixing a carboxylic acid and a metal salt of a carboxylic acid that is the same as or different from the carboxylic acid). It acts as a condensation catalyst (terminal blocking catalyst) for blocking the silanol groups at both ends of the molecular chain in the above-mentioned (A) component with the hydrolyzable silyl groups in the hydrolyzable organosilane compound and / or its partial hydrolysis condensate of the following (C) component, and also acts as a condensation catalyst (curing catalyst) for promoting the condensation and curing reaction of the whole composition.

[0021] (B) The carboxylic acid contained in the condensation catalyst may be one or more (particularly one or two) carboxylic acids having one or more carboxyl groups (C(=O)OH) in the molecule, and having 1 or more carbon atoms, and may be selected from saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, and aromatic carboxylic acids (carboxylic acids in which the carboxyl group is bonded to a carbon atom constituting an aromatic ring), and as the aliphatic carboxylic acid (carboxylic acid in which the carboxyl group is bonded to a carbon atom constituting an aliphatic hydrocarbon group), it may be a carboxylic acid having a linear, branched, or aliphatic cyclic hydrocarbon chain, or may be an aliphatic carboxylic acid having an aromatic cyclic hydrocarbon chain in the molecule.The carboxylic acid preferably has 1 to 30 carbon atoms, particularly 1 to 22 carbon atoms in the molecule. Specific examples thereof include saturated aliphatic monocarboxylic acids such as methanoic acid (formic acid), ethanoic acid (acetic acid), propanoic acid (propionic acid), butanoic acid (butyric acid), pentanoic acid (valeric acid), hexanoic acid (caproic acid), heptanoic acid (enanthic acid), octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic acid (stearic acid), etc.; unsaturated aliphatic monocarboxylic acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, sorbic acid, etc.; saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, etc.; unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, etc.; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, etc.; branched saturated aliphatic monocarboxylic acids such as tert-butylacetic acid, 2-methylbutyric acid, 2-methylbutanoic acid, 2,2-dimethylbutyric acid, 2,2-dimethylvaleric acid, 3,3,5-trimethylhexanoic acid, 3-methylcrotonic acid, 2-ethylhexanoic acid, 2-hexyldecanoic acid, neodecanoic acid, etc.; saturated aliphatic monocarboxylic acids having a saturated aliphatic hydrocarbon chain such as cyclopropanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclopropylcarboxylic acid, cyclohexylcarboxylic acid, cyclopropylcarboxylic acid, etc.; unsaturated aliphatic monocarboxylic acids having an unsaturated aliphatic hydrocarbon chain such as 1-cyclohexene-1-carboxylic acid, etc.; aliphatic carboxylic acids having an aromatic hydrocarbon chain in the molecule such as biphenylacetic acid, etc.; saturated aliphatic monocarboxylic acids containing a carbonyl group in a saturated aliphatic hydrocarbon group such as levulinic acid, etc. Particularly preferred are those such as 2-ethylhexanoic acid which have a small number of carbon atoms, contain a branched chain, and have little odor.

[0022] (B) The carboxylic acid residue constituting the metal carboxylate contained in the condensation catalyst may be derived from the above-described carboxylic acid (one or more carboxyl groups in the molecule, a saturated aliphatic carboxylic acid having 1 or more carbon atoms, an unsaturated aliphatic carboxylic acid, and an aromatic carboxylic acid, one or more carboxylic acids selected therefrom). In particular, the metal carboxylate is preferably derived from the same carboxylic acid as the above carboxylic acid.

[0023] (B) The metal atom contained in the metal carboxylate contained in the condensation catalyst is preferably a monovalent to trivalent one. Specifically, lithium, sodium, potassium, magnesium, calcium, zinc, tin, titanium, bismuth, etc. may be mentioned, and preferably lithium, sodium, potassium, magnesium, calcium, zinc, bismuth may be mentioned. In particular, those such as calcium, which are inexpensive and have little concern about toxicity to the human body and the environment, are preferable.

[0024] Examples of the metal carboxylate contained in the condensation catalyst of component (B) include metal salts of saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, and aromatic carboxylic acids (metal salts of carboxylic acids in which the carboxyl group is bonded to a carbon atom constituting an aromatic ring) having one or more (particularly one or two) carbonyloxy groups (i.e., carboxylic acid residues represented by -C(=O)O that form a salt with a metal atom and a carboxyl group (C(=O)OH)) in the molecule, and one or more carbon atoms. The metal salt of the aliphatic carboxylic acid (metal salt of a carboxylic acid in which the carboxyl group is bonded to a carbon atom constituting an aliphatic hydrocarbon group) may be a metal salt of a carboxylic acid having a linear, branched, or aliphatic cyclic hydrocarbon chain, or a metal salt of an aliphatic carboxylic acid having an aromatic cyclic hydrocarbon chain in the molecule. The metal carboxylate preferably has 1 to 30, particularly 1 to 22 carbon atoms in the molecule. Specific examples thereof include lithium methanoate (lithium formate), lithium ethanoate (lithium acetate), lithium propanoate (lithium propionate), lithium butanoate (lithium butyrate), lithium pentanoate (lithium valerate), lithium hexanoate (lithium caproate), lithium heptanoate (lithium enanthate), lithium octanoate (lithium caprylate), lithium nonanoate (lithium pelargonate), lithium decanoate (lithium caprate), lithium dodecanoate (lithium laurate), lithium tetradecanoate (lithium myristate), lithium hexadecanoate (lithium palmitate), lithium heptadecanoate, lithium octadecanoate (lithium stearate), sodium methanoate (sodium formate), sodium ethanoate (sodium acetate), sodium propanoate (sodium propionate), sodium butanoate (sodium butyrate), sodium pentanoate (sodium valerate), sodium hexanoate (sodium caproate), sodium heptanoate (sodium enanthate), sodium octanoate (sodium caprylate), sodium nonanoate (sodium pelargonate), sodium decanoate (sodium caprate), sodium dodecanoate (sodium laurate), sodium tetradecanoate (sodium myristate),Sodium hexadecanoate (sodium palmitate), sodium heptadecanoate, sodium octadecanoate (sodium stearate), potassium methanoate (potassium formate), potassium ethanoate (potassium acetate), potassium propanoate (potassium propionate), potassium butanoate (potassium butyrate), potassium pentanoate (potassium valerate), potassium hexanoate (potassium caproate), potassium heptanoate (potassium enanthate), potassium octanoate (potassium caprylate), potassium nonanoate (potassium pelargonate), potassium decanoate (potassium caprate), potassium dodecanoate (potassium laurate), potassium tetradecanoate (potassium myristate), potassium hexadecanoate (potassium palmitate), potassium heptadecanoate, potassium octadecanoate (potassium stearate), magnesium methanoate (magnesium formate), magnesium ethanoate (magnesium acetate), magnesium propanoate (magnesium propionate), magnesium butanoate (magnesium butyrate), magnesium pentanoate (magnesium valerate), magnesium hexanoate (magnesium caproate), magnesium heptanoate (magnesium enanthate), magnesium octanoate (magnesium caprylate), magnesium nonanoate (magnesium pelargonate), magnesium decanoate (magnesium caprate), magnesium dodecanoate (magnesium laurate), magnesium tetradecanoate (magnesium myristate), magnesium hexadecanoate (magnesium palmitate), magnesium heptadecanoate, magnesium octadecanoate (magnesium stearate), calcium methanoate (calcium formate), calcium ethanoate (calcium acetate), calcium propanoate (calcium propionate), calcium butanoate (calcium butyrate), calcium pentanoate (calcium valerate), calcium hexanoate (calcium caproate), calcium heptanoate (calcium enanthate), calcium octanoate (calcium caprylate), calcium nonanoate (calcium pelargonate), calcium decanoate (calcium caprate), calcium dodecanoate (calcium laurate), calcium tetradecanoate (calcium myristate),Calcium hexadecanoate (calcium palmitate), calcium heptadecanoate, calcium octadecanoate (calcium stearate), zinc methanoate (zinc formate), zinc ethanoate (zinc acetate), zinc propanoate (zinc propionate), zinc butanoate (zinc butyrate), zinc pentanoate (zinc valerate), zinc hexanoate (zinc caproate), zinc heptanoate (zinc enanthate), zinc octanoate (zinc caprylate), zinc nonanoate (zinc pelargonate), zinc decanoate (zinc caprate), zinc dodecanoate (zinc laurate), zinc tetradecanoate (zinc myristate), zinc hexadecanoate (zinc palmitate), zinc heptadecanoate, zinc octadecanoate (zinc stearate), tin methanoate (tin formate), tin ethanoate (tin acetate), tin propanoate (tin propionate), tin butanoate (tin butyrate), tin pentanoate (tin valerate), tin hexanoate (tin caproate), tin heptanoate (tin enanthate), tin octanoate (tin caprylate), tin nonanoate (tin pelargonate), tin decanoate (tin caprate), tin dodecanoate (tin laurate), tin tetradecanoate (tin myristate), tin hexadecanoate (tin palmitate), tin heptadecanoate, tin octadecanoate (tin stearate), titanium methanoate (titanium formate), titanium ethanoate (titanium acetate), titanium propanoate (titanium propionate), titanium butanoate (titanium butyrate), titanium pentanoate (titanium valerate), titanium hexanoate (titanium caproate), titanium heptanoate (titanium enanthate), titanium octanoate (titanium caprylate), titanium nonanoate (titanium pelargonate), titanium decanoate (titanium caprate), titanium dodecanoate (titanium laurate), titanium tetradecanoate (titanium myristate), titanium hexadecanoate (titanium palmitate), titanium heptadecanoate, titanium octadecanoate (titanium stearate), bismuth methanoate (bismuth formate), bismuth ethanoate (bismuth acetate), bismuth propanoate (bismuth propionate), bismuth butanoate (bismuth butyrate), bismuth pentanoate (bismuth valerate), bismuth hexanoate (bismuth caproate), bismuth heptanoate (bismuth enanthate), bismuth octanoate (bismuth caprylate), bismuth nonanoate (bismuth pelargonate), bismuth decanoate (bismuth caprate),Metal salts of saturated aliphatic monocarboxylic acids such as bismuth dodecanoate (bismuth laurate), bismuth tetradecanoate (bismuth myristate), bismuth hexadecanoate (bismuth palmitate), bismuth heptadecanoate, bismuth octadecanoate (bismuth stearate), etc., lithium oleate, lithium linoleate, lithium linolenate, lithium arachidonate, lithium eicosapentaenoate, lithium docosahexaenoate, lithium sorbate, sodium oleate, sodium linoleate, sodium linolenate, sodium arachidonate, sodium eicosapentaenoate, sodium docosahexaenoate, sodium sorbate, potassium oleate, potassium linoleate, potassium linolenate, potassium arachidonate, potassium eicosapentaenoate, potassium docosahexaenoate, potassium sorbate, magnesium oleate, magnesium linoleate, magnesium linolenate, magnesium arachidonate, magnesium eicosapentaenoate, magnesium docosahexaenoate, magnesium sorbate, calcium oleate, calcium linoleate, calcium linolenate, calcium arachidonate, calcium eicosapentaenoate, calcium docosahexaenoate, calcium sorbate, zinc oleate, zinc linoleate, zinc linolenate, zinc arachidonate, zinc eicosapentaenoate, zinc docosahexaenoate, zinc sorbate, tin oleate, tin linoleate, tin linolenate, tin arachidonate, tin eicosapentaenoate, tin docosahexaenoate, tin sorbate, titanium oleate, titanium linoleate, titanium linolenate, titanium arachidonate, titanium eicosapentaenoate, titanium docosahexaenoate, titanium sorbate, bismuth oleate, bismuth linoleate, bismuth linolenate, bismuth arachidonate, bismuth eicosapentaenoate, bismuth docosahexaenoate, bismuth sorbate, etc., metal salts of unsaturated aliphatic monocarboxylic acids, lithium oxalate, lithium malonate, lithium succinate, lithium glutarate, lithium adipate, sodium oxalate, sodium malonate, sodium succinate, sodium glutarate, sodium adipate, potassium oxalate, potassium malonate, potassium succinate, potassium glutarate, potassium adipate,Metal salts of saturated aliphatic dicarboxylic acids such as magnesium oxalate, magnesium malonate, magnesium succinate, magnesium glutarate, magnesium adipate, calcium oxalate, calcium malonate, calcium succinate, calcium glutarate, calcium adipate, zinc oxalate, zinc malonate, zinc succinate, zinc glutarate, zinc adipate, tin oxalate, tin malonate, tin succinate, tin glutarate, tin adipate, titanium oxalate, titanium malonate, titanium succinate, titanium glutarate, titanium adipate, bismuth oxalate, bismuth malonate, bismuth succinate, bismuth glutarate, bismuth adipate, etc.; metal salts of unsaturated aliphatic dicarboxylic acids such as lithium maleate, lithium fumarate, sodium maleate, sodium fumarate, potassium maleate, potassium fumarate, magnesium maleate, magnesium fumarate, calcium maleate, calcium fumarate, zinc maleate, zinc fumarate, tin maleate, tin fumarate, titanium maleate, titanium fumarate, bismuth maleate, bismuth fumarate, etc.; lithium aromatic carboxylates such as lithium benzoate, lithium phthalate, lithium isophthalate, lithium terephthalate, lithium salicylate; sodium aromatic carboxylates such as sodium benzoate, sodium phthalate, sodium isophthalate, sodium terephthalate, sodium salicylate; lithium salts of branched-chain aliphatic carboxylic acids such as lithium tert-butylacetate, lithium 2-methylbutyrate, lithium 2-methylbutanoate, lithium 2,2-dimethylbutyrate, lithium 2,2-dimethylvalerate, lithium 3,3,5-trimethylhexanoate, lithium 3-methylcrotonate, lithium 2-ethylhexanoate, lithium 2-hexyldecanoate, lithium neodecanoate; sodium salts of branched-chain aliphatic carboxylic acids such as sodium tert-butylacetate, sodium 2-methylbutyrate, sodium 2-methylbutanoate, sodium 2,2-dimethylbutyrate, sodium 2,2-dimethylvalerate, sodium 3,3,5-trimethylhexanoate, sodium 3-methylcrotonate, Sodium 2-ethylhexanoate, sodium 2-hexyldecanoate, sodium neodecanoate, potassium benzoate, potassium phthalate, potassium isophthalate, potassium terephthalate, potassium salicylate and other potassium aromatic carboxylates, potassium tert-butylacetate, potassium 2-methylbutyrate, potassium 2-methylbutanoate, potassium 2,2-dimethylbutyrate, potassium 2,2-dimethylvalerate, potassium 3,3,5-trimethylhexanoate, potassium 3-methylcrotonate, potassium 2-ethylhexanoate, potassium 2-hexyldecanoate, potassium neodecanoate, magnesium benzoate, magnesium phthalate, magnesium isophthalate, magnesium terephthalate, magnesium salicylate and other magnesium aromatic carboxylates, magnesium tert-butylacetate, magnesium 2-methylbutyrate, magnesium 2-methylbutanoate, magnesium 2,2-dimethylbutyrate, magnesium 2,2-dimethylvalerate, magnesium 3,3,5-trimethylhexanoate, magnesium 3-methylcrotonate, magnesium 2-ethylhexanoate, magnesium 2-hexyldecanoate, magnesium neodecanoate, calcium benzoate, calcium phthalate, calcium isophthalate, calcium terephthalate, calcium salicylate and other calcium aromatic carboxylates, calcium tert-butylacetate, calcium 2-methylbutyrate, calcium 2-methylbutanoate, calcium 2,2-dimethylbutyrate, calcium 2,2-dimethylvalerate, calcium 3,3,5-trimethylhexanoate, calcium 3-methylcrotonate, calcium 2-ethylhexanoate, calcium 2-hexyldecanoate, calcium neodecanoate, calcium undecenoate, zinc benzoate, zinc phthalate, zinc isophthalate, zinc terephthalate, zinc salicylate and other zinc aromatic carboxylates, zinc tert-butylacetate, zinc 2-methylbutyrate, zinc 2-methylbutanoate, zinc 2,2-dimethylbutyrate, zinc 2,2-dimethylvalerate, zinc 3,3,5-trimethylhexanoate, zinc 3-methylcrotonate, zinc 2-ethylhexanoate, zinc 2-hexyldecanoate, zinc neodecanoate, tin benzoate, tin phthalate, tin isophthalate, tin terephthalate, tin salicylate and other tin aromatic carboxylates, tin tert-butylacetate, tin 2-methylbutyrate,Tin 2-methylbutanoate, tin 2,2-dimethylbutanoate, tin 2,2-dimethylvalerate, tin 3,3,5-trimethylhexanoate, tin 3-methylcrotonate, tin 2-ethylhexanoate, tin 2-hexyldecanoate, tin neodecanoate, titanium benzoate, titanium phthalate, titanium isophthalate, titanium terephthalate, titanium salicylate and other aromatic carboxylic acid titanates, titanium tert-butylacetate, titanium 2-methylbutanoate, titanium 2-methylbutyrate, titanium 2,2-dimethylbutanoate, titanium 2,2-dimethylvalerate, titanium 3,3,5-trimethylhexanoate, titanium 3-methylcrotonate, titanium 2-ethylhexanoate, titanium 2-hexyldecanoate, titanium neodecanoate, bismuth benzoate, bismuth phthalate, bismuth isophthalate, bismuth terephthalate, bismuth salicylate and other aromatic carboxylic acid bismuths, bismuth tert-butylacetate, bismuth 2-methylbutanoate, bismuth 2-methylbutyrate, bismuth 2,2-dimethylbutanoate, bismuth 2,2-dimethylvalerate, bismuth 3,3,5-trimethylhexanoate, bismuth 3-methylcrotonate, bismuth 2-ethylhexanoate, bismuth 2-hexyldecanoate, bismuth neodecanoate and other metal salts of branched saturated aliphatic monocarboxylic acids, lithium cyclopropanecarboxylate, lithium cyclopentanecarboxylate, lithium cyclohexanecarboxylate, lithium cyclopropylcarboxylate, lithium cyclohexylcarboxylate, lithium cyclopropylcarboxylate, sodium cyclopropanecarboxylate, sodium cyclopentanecarboxylate, sodium cyclohexanecarboxylate, sodium cyclopropylcarboxylate, sodium cyclohexylcarboxylate, sodium cyclopropylcarboxylate, potassium cyclopropanecarboxylate, potassium cyclopentanecarboxylate, potassium cyclohexanecarboxylate, potassium cyclopropylcarboxylate, potassium cyclohexylcarboxylate, potassium cyclopropylcarboxylate, magnesium cyclopropanecarboxylate, magnesium cyclopentanecarboxylate, magnesium cyclohexanecarboxylate, magnesium cyclopropylcarboxylate, magnesium cyclohexylcarboxylate, magnesium cyclopropylcarboxylate, calcium cyclopropanecarboxylate, calcium cyclopentanecarboxylate,Metal salts of saturated aliphatic monocarboxylic acids having a saturated aliphatic cyclic hydrocarbon chain such as calcium cyclohexanecarboxylate, calcium cyclopropylcarboxylate, calcium cyclohexylcarboxylate, calcium cyclopropylcarboxylate, zinc cyclopropanecarboxylate, zinc cyclopentanecarboxylate, zinc cyclohexanecarboxylate, zinc cyclopropylcarboxylate, zinc cyclohexylcarboxylate, zinc cyclopropylcarboxylate, tin cyclopropanecarboxylate, tin cyclopentanecarboxylate, tin cyclohexanecarboxylate, tin cyclopropylcarboxylate, tin cyclohexylcarboxylate, tin cyclopropylcarboxylate, titanium cyclopropanecarboxylate, titanium cyclopentanecarboxylate, titanium cyclohexanecarboxylate, titanium cyclopropylcarboxylate, titanium cyclohexylcarboxylate, titanium cyclopropylcarboxylate, bismuth cyclopropanecarboxylate, bismuth cyclopentanecarboxylate, bismuth cyclohexanecarboxylate, bismuth cyclopropylcarboxylate, bismuth cyclohexylcarboxylate, bismuth cyclopropylcarboxylate, metal salts of unsaturated aliphatic monocarboxylic acids having an unsaturated aliphatic cyclic hydrocarbon chain such as lithium 1-cyclohexene-1-carboxylate, sodium 1-cyclohexene-1-carboxylate, potassium 1-cyclohexene-1-carboxylate, magnesium 1-cyclohexene-1-carboxylate, calcium 1-cyclohexene-1-carboxylate, zinc 1-cyclohexene-1-carboxylate, tin 1-cyclohexene-1-carboxylate, titanium 1-cyclohexene-1-carboxylate, bismuth 1-cyclohexene-1-carboxylate, metal salts of aliphatic carboxylic acids having an aromatic cyclic hydrocarbon chain in the molecule such as lithium biphenylacetate, sodium biphenylacetate, potassium biphenylacetate, magnesium biphenylacetate, calcium biphenylacetate, zinc biphenylacetate, tin biphenylacetate, titanium biphenylacetate, bismuth biphenylacetate, metal salts of saturated aliphatic monocarboxylic acids containing a carbonyl group in a saturated aliphatic hydrocarbon group such as lithium levulinate, sodium levulinate, potassium levulinate, magnesium levulinate, calcium levulinate, zinc levulinate, tin levulinate, titanium levulinate, bismuth levulinate, etc. can be exemplified.Among these, calcium 2-ethylhexanoate, calcium 2-hexyldecanoate, calcium undecenoate, and calcium benzoate are preferred in terms of low cost and safety to the human body and the environment.

[0025] (B) In the condensation catalyst of the component, the mixing ratio of the carboxylic acid and the metal carboxylate is preferably 1:99 to 50:50, particularly preferably 5:95 to 40:60, in terms of mass ratio of metal carboxylate:carboxylic acid. If there is too much carboxylic acid (too little metal carboxylate) or too much metal carboxylate (too little carboxylic acid), the function as a condensation catalyst may be significantly impaired.

[0026] (B) In the condensation catalyst of the component, the mixing method of the carboxylic acid and the metal carboxylate may be any method as long as both components are uniformly mixed without being unevenly distributed in the mixture. For example, under moisture shielding, using a shaker or the like, at room temperature (23°C ± 15°C) for 2 to 12 hours, particularly about 3 to 8 hours until the undissolved components disappear and it becomes uniform.

[0027] (B) The compounding amount of the condensation catalyst of the component is 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the organopolysiloxane in which both ends of the molecular chain of the above-mentioned (A) component are blocked with silanol groups. If the condensation catalyst is too little, the blocking reaction of the terminal silanol group of the (A) component to the hydrolyzable silyl group may not proceed sufficiently, and the storage stability of the composition may decrease. If it is too much, the curing rate may slow down, and the mechanical properties of the resulting cured product may decrease.

[0028] (C) component In the method for producing a room-temperature curable organopolysiloxane composition of the present invention, the room-temperature curable organopolysiloxane composition contains, as component (C), a terminal blocking agent for blocking the silanol groups at both ends of the molecular chain in component (A) described above with a hydrolyzable silyl group and a crosslinking agent (curing agent) for improving the crosslinking density of the cured product in the presence of the condensation catalyst of component (B) described above, a hydrolyzable organosilane compound and / or its partial hydrolysis condensate, particularly a hydrolyzable organosilane compound having three or more (particularly three or four) hydrolyzable groups bonded to silicon atoms in the molecule and / or its partial hydrolysis condensate. In the present invention, the "partial hydrolysis condensate" means an organosiloxane oligomer having three or more remaining hydrolyzable groups in the molecule produced by partially hydrolyzing and condensing a hydrolyzable organosilane compound.

[0029] (C) Examples of the hydrolyzable group bonded to the silicon atom of the hydrolyzable organosilane compound and / or its partial hydrolysis condensate include a ketoxime group having 3 to 7 carbon atoms such as a dimethylketoxime group, a methylethylketoxime group, and a diethylketoxime group; an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group; an acyloxy group having 2 to 10 carbon atoms such as an acetoxy group, an octanoyloxy group, and a benzoyloxy group; and an alkenyloxy group having 2 to 4 carbon atoms such as a vinyloxy group, an allyloxy group, a propenoxy group, and an isopropenoxy group. An alkoxy group having 1 to 4 carbon atoms and an isopropenoxy group are preferred. Examples of the organo group (monovalent hydrocarbon group) bonded to the silicon atom other than the above hydrolyzable group of the hydrolyzable organosilane compound and / or its partial hydrolysis condensate include an alkyl group having 1 to 10 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group; an alkenyl group having 2 to 10 carbon atoms such as a vinyl group and an allyl group; and an aryl group having 6 to 10 carbon atoms such as a phenyl group and a tolyl group. An alkyl group having 1 to 4 carbon atoms is preferred. In addition, as the hydrolyzable organosilane compound of component (C), a bissilyl-type hydrolyzable silane compound in which a plurality (two or three) of silyl groups having hydrolyzable groups are linked to each other by a divalent hydrocarbon group such as an alkylene group, a trissilyl-type hydrolyzable silane compound, etc. may be used.

[0030] Specific examples of component (C) include alkoxysilanes such as methyltrimethoxysilane, octyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, 2-ethylhexyl α-(dimethoxymethylsilyl)propionate; isopropenoxy group-containing silanes such as methyltriisopropenoxysilane, ethyltriisopropenoxysilane, vinyltriisopropenoxysilane, phenyltriisopropenoxysilane; acetoxysilanes such as methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane; and partial hydrolysis condensates of these silanes. These can be used alone or in combination of two or more. It should be noted that the hydrolyzable organosilane compound of component (C) and / or its partial hydrolysis condensate is clearly distinguished from the adhesion promoter of component (F) described later in that it does not have a monovalent hydrocarbon group having a functional group containing a heteroatom selected from nitrogen, oxygen, and sulfur as a group other than the hydrolyzable group in the molecule.

[0031] The blending amount of component (C) is usually 0.1 to 30 parts by mass, preferably 0.2 to 20 parts by mass, more preferably 0.5 to 15 parts by mass with respect to 100 parts by mass of the above component (A). If the blending amount is 0.1 part by mass or more, the end-capping reaction and the cross-linking (curing) reaction proceed sufficiently, and if the blending amount is 30 parts by mass or less, the cured product does not become too hard and is also economical, which is preferable.

[0032] Component (D) In the method for producing a room-temperature curable organopolysiloxane composition of the present invention, the room-temperature curable organopolysiloxane composition contains a filler ((D) component) for imparting sufficient mechanical strength to the cured product. As this filler, known ones can be used. For example, silicon oxides such as fine powder silica, fumed silica, silica aerogel, precipitated silica, and diatomaceous earth; metal oxides such as iron oxide, zinc oxide, and titanium oxide, or those obtained by subjecting their surfaces to silane treatment; metal carbonates such as calcium carbonate, magnesium carbonate, and zinc carbonate; inorganic fillers such as asbestos, glass wool, carbon black, fine mica powder, and fused silica powder; or synthetic resin powders such as polystyrene, polyvinyl chloride, and polypropylene are used.

[0033] (D) component is compounded in an amount of 1 to 1,000 parts by mass, preferably 5 to 200 parts by mass, based on 100 parts by mass of the above (A) component. By compounding 1 part by mass or more of the (D) component, the cured product obtained from the room-temperature curable organopolysiloxane composition has sufficient mechanical strength, and if the compounding amount is 1,000 parts by mass or less, the viscosity of the composition does not increase to deteriorate workability, nor does the rubber strength of the cured product decrease to deteriorate rubber elasticity.

[0034] (E) component In the method for producing a room-temperature curable organopolysiloxane composition of the present invention, as an optional component that can be compounded as necessary, a curing catalyst other than the above-mentioned (B) component ((E) component) can be compounded in the room-temperature curable organopolysiloxane composition. The (E) component is a curing catalyst other than the (B) component (non-metal-based organic catalyst and / or metal-based catalyst), and is for use as a curing catalyst for the room-temperature curable organopolysiloxane composition.

[0035] As the non-metallic organic catalyst of the curing catalyst, those known as the curing accelerator of the condensation-curing type organopolysiloxane composition can be used, and there is no particular limitation. For example, phosphazene-containing compounds such as N,N,N’,N’,N'',N''-hexamethyl-N'''-(trimethylsilylmethyl)-phosphorimidic triamide, amine compounds such as n-octylamine, hexylamine, dodecylamine phosphate, tetramethylguanidine or salts thereof, quaternary ammonium salts such as benzyltriethylammonium acetate, dialkylhydroxylamines such as dimethylhydroxylamine, diethylhydroxylamine, hydrolyzable silanes and siloxanes having a guanidyl group such as tetramethylguanidylpropyltrimethoxysilane, tetramethylguanidylpropylmethyldimethoxysilane, tetramethylguanidylpropyltris(trimethylsiloxy)silane, etc. are exemplified, but the non-metallic organic catalyst is not limited thereto. Further, the non-metallic organic catalyst may be used alone or in admixture of two or more.

[0036] As the metal catalyst of the curing catalyst, those known as curing accelerators for condensation-curing organopolysiloxanes can be used, and there is no particular limitation. For example, alkyltin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctoate, dioctyltin dineodecanoate, di-n-butyl-dimethoxysn; titanate or titanium chelate compounds such as tetraisopropoxytitanium, tetra-n-butoxytitanium, tetrakis(2-ethylhexoxy)titanium, dipropoxybis(acetylacetonato)titanium, titanium isopropoxyoctylene glycol; zinc naphthenate, zinc stearate, zinc-2-ethyloctoate, iron-2-ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, cobalt naphthenate, alcoholate aluminum compounds such as aluminum isopropylate, aluminum secondary butyrate; aluminum chelate compounds such as aluminum alkylacetate·diisopropylate, aluminum bisethylacetoacetate·monoacetylacetonate; lower fatty acid salts of alkali metals such as potassium acetate, sodium acetate, lithium oxalate are exemplified, but the metal catalyst is not limited thereto. Further, the metal catalyst may be used alone or in combination of two or more. In addition, when an amine-based curing catalyst is used as the curing catalyst of the (E) component, the cured product of the organopolysiloxane after curing may discolor under high temperature and UV irradiation, so a non-amine-based curing catalyst is preferred.

[0037] The blending amount of the curing catalyst of the (E) component is 0 to 15 parts by mass with respect to 100 parts by mass of the above (A) component. When blending, it is preferably 0.001 to 15 parts by mass, and more preferably 0.01 to 10 parts by mass. If the blending amount of the (E) component is too large, the curability will be too fast, resulting in insufficient working time and being economically disadvantageous in some cases.

[0038] (F) component In the method for producing a room-temperature curable organopolysiloxane composition of the present invention, an adhesion promoter as component (F) can be blended as an optional component that can be blended as necessary in the room-temperature curable organopolysiloxane composition. Examples of the adhesion promoter as component (F) include aminofunctional group-containing alkoxysilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyl(methyl)dimethoxysilane; epoxyfunctional group-containing alkoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and silane coupling agents (carbon-functional hydrolyzable silanes) such as isocyanate-functional group-containing alkoxysilanes. When an amine-based compound is used as the adhesion promoter of component (F), the cured organopolysiloxane may discolor under high temperature or UV irradiation, so it is preferable to use a non-amine-based compound.

[0039] The blending amount of the adhesion promoter of component (F) is 0 to 30 parts by mass with respect to 100 parts by mass of the organopolysiloxane of component (A). When blending, it is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and still more preferably 0.2 to 10 parts by mass. If the above blending amount exceeds 30 parts by mass, it may be economically disadvantageous or the stability of the composition may decrease.

[0040] -Other Additives- Also, in the method for producing the room-temperature curable organopolysiloxane composition of the present invention, in addition to the above-described components (A) to (D) (or components (A) to (F) as necessary), the room-temperature curable organopolysiloxane composition may further contain, as additives, at least one known additive selected from pigments, dyes, anti-aging agents, antioxidants, antistatic agents, antimony oxide, flame retardants such as chlorinated paraffin, and viscosity modifiers such as non-functional diorganopolysiloxanes (non-functional dimethyl silicone oil) having trimethylsilyl groups blocked at both ends, etc., within a range not impairing the object of the present invention. Further, a polyether as a thixotropy improver, or a fungicide, an antibacterial agent, an adhesion aid, etc. can also be blended within a range not impairing the object of the present invention.

[0041] [Method for producing room-temperature curable organopolysiloxane composition] In the present invention, the room-temperature curable organopolysiloxane composition is produced by the following method. That is, with respect to the above-described components (A) to (D) (or components (A) to (F)), [i]: A step of mixing all of component (A) and part or all of component (C) in the presence of all of component (B) to block the silanol groups at both ends of the molecular chain of the organopolysiloxane of component (A) with hydrolyzable silyl groups, and then, [ii]: A step of mixing the remainder of component (C) and all of component (D) into the reaction mixture obtained by mixing and reacting all of component (A), all of component (B), and part or all of component (C) obtained in step [i]. It is produced by a production method including step [i] and step [ii].

[0042] Among the (C) component, the terminal blocker and crosslinking agent (curing agent) for blocking the silanol groups at both ends of the molecular chain of the (A) component with hydrolyzable silyl groups in the presence of the condensation catalyst of the (B) component described above are formulated in step [i] in an amount of 40% by mass or more (40 to 100% by mass), particularly preferably 50% by mass or more (50 to 100% by mass), and even more preferably 60% by mass or more (60 to 100% by mass). Therefore, the remainder of the (C) component formulated in step [ii] is preferably 60% by mass or less (0 to 60% by mass), particularly preferably 50% by mass or less (0 to 50% by mass), and even more preferably 40% by mass or less (0 to 40% by mass) of the total (C) component.

[0043] Also, the mixing order of the optional components (E) component, (F) component, and other additives that are formulated as necessary is not particularly limited, but it is preferably formulated in step [ii].

[0044] In step [i], the mixing of the (A) component and part or all of the (C) component in the presence of the (B) component only requires that the silanol groups at both ends of the molecular chain in the (A) component be blocked with the hydrolyzable silyl groups in the (C) component. The mixing conditions are as follows: under moisture shielding, at normal temperature (usually 0 to 40°C, preferably 10 to 30°C), usually for 10 minutes to 5 hours, preferably about 30 minutes to 3 hours. Also, the mixing is preferably carried out under normal pressure.

[0045] In step [ii], as the mixing conditions for mixing the remainder of the (C) component and the (D) component into the reaction mixture obtained by mixing and reacting part or all of the above (A) component, (B) component, and (C) component obtained in step [i], under moisture shielding, heat to normal temperature or, if necessary, to about 40 to 120°C. The mixing time may be a time sufficient for the above components to become uniform, usually 10 minutes to 3 hours, preferably about 30 minutes to 3 hours. Also, the mixing is preferably carried out under normal pressure or reduced pressure.

[0046] Furthermore, with respect to the reaction mixture obtained by mixing and reacting some or all of the above-mentioned components (A), (B), and (C) obtained in step [i], after step [i] (i.e., before step [ii], during step [ii], or after step [ii]), a basic substance such as an amine compound such as methylamine, dimethylamine, ethylamine, diethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, sec-butylamine, tert-butylamine, dibutylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, ethylenediamine, hexamethylenediamine, aniline, phenethylamine, toluidine, pyrrolidine, piperidine, piperazine, morpholine, pyrrole, pyrazole, imidazole, etc. may be added to the reaction mixture to neutralize the reaction mixture.

[0047] The room-temperature curable organopolysiloxane composition produced as described above can easily undergo a crosslinking (curing) reaction in a short time due to moisture (water) in the air at room temperature (23°C ± 15°C), giving an organopolysiloxane cured product such as a silicone rubber cured product (elastomeric elastomer) or a silicone gel cured product. Moreover, the cured product (silicone rubber cured product or silicone gel cured product) after curing does not discolor even when exposed to high temperatures or UV. In addition, the room-temperature curable organopolysiloxane composition obtained by such a production method of the present invention can be suitably used as a coating agent, an adhesive, or a sealing material.

Examples

[0048] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples. In the following examples, the preparation of the composition was carried out at 23°C, and the viscosity is shown as the measured value by a rotational viscometer at 23°C. Also, room temperature means 23°C.

[0049] 0.7 parts by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid used in Examples 1 to 3 below were uniformly mixed in advance with shaking at room temperature for 5 hours under moisture shielding to prepare a uniform mixture (condensation catalyst).

[0050] [Example 1] To 100 parts by mass of dimethylpolysiloxane blocked at both molecular chain ends with hydroxyl groups (silanol groups) bonded to silicon atoms and having a viscosity of 50,000 mPa·s, 3.4 parts by mass of a mixture (condensation catalyst) prepared by uniformly mixing 0.7 parts by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid in advance, 5.0 parts by mass of trimethoxy(methyl)silane, and 42.3 parts by mass of dimethylpolysiloxane blocked at both ends with trimethylsilyl groups and having a viscosity of 100 mPa·s were added, and the mixture was uniformly mixed at room temperature for 30 minutes under moisture shielding to prepare a reaction mixture (Step [i]). Next, 15 parts by mass of fumed silica (MU-215, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the reaction mixture, and the mixture was mixed at room temperature for 40 minutes under reduced pressure. Then, 3.3 parts by mass of a partial hydrolysis / condensate of trimethoxy(methyl)silane (methoxy group-containing methylsiloxane oligomer, degree of polymerization: 2 to 8) was added, and the mixture was mixed at room temperature for 20 minutes. After that, the mixture was mixed at room temperature for 15 minutes under reduced pressure to obtain Composition 1 (Step [ii]).

[0051] [Example 2] In the production method of Example 1, after adding 3.3 parts by mass of a partial hydrolysis / condensate of trimethoxy(methyl)silane (methoxy group-containing methylsiloxane oligomer) in Step [ii] and mixing at room temperature for 20 minutes, 0.3 part by mass of dioctyltin dineodecanoate was added and the mixture was mixed at room temperature for 15 minutes under reduced pressure. Composition 2 was obtained in the same manner as in Example 1 except for the above.

[0052] [Example 3] In the production method of Example 2, Composition 3 was obtained in the same manner as in Example 2 except that 0.3 part by mass of tetra-n-butoxytitanium was used instead of 0.3 part by mass of dioctyltin dineodecanoate in Step [ii].

[0053] [Comparative Example 1] In the production method of Example 2, instead of 3.4 parts by mass of a mixture (condensation catalyst) prepared by uniformly mixing 0.7 part by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid in advance in Step [i], 1.3 parts by mass of a compound (N-(aminomethylphenylenemethyl)-3-aminopropyltrimethoxysilane, trade name: CF-73, manufactured by Shin-Etsu Chemical Co., Ltd.) obtained by a dehydrochlorination reaction of xylylenediamine and 3-chloropropyltrimethoxysilane was used. In Step [ii], simultaneously with the addition of 3.3 parts by mass of a partial hydrolysis / condensate of trimethoxy(methyl)silane (a methoxy group-containing methylsiloxane oligomer), 0.8 part by mass of hexamethyldisilazane and 1.7 parts by mass of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) were added. Composition 4 was obtained in the same manner as in Example 2 except for the above.

[0054] [Comparative Example 2] In a composition composed of the same components as in Example 1, 0.7 part by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid were separately added to 100 parts by mass of dimethylpolysiloxane blocked at both molecular chain ends with hydroxyl groups (silanol groups) bonded to silicon atoms and having a viscosity of 50,000 mPa·s. Further, 5.0 parts by mass of trimethoxy(methyl)silane and 42.3 parts by mass of dimethylpolysiloxane blocked at both ends with trimethylsilyl groups and having a viscosity of 100 mPa·s were added, and then the mixture was uniformly mixed at room temperature for 30 minutes under moisture shielding to prepare a mixture (Step [i]). Next, 15 parts by mass of fumed silica (MU-215, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the mixture, and the mixture was mixed at room temperature for 40 minutes under reduced pressure. Then, 3.3 parts by mass of a partial hydrolysis / condensate of trimethoxy(methyl)silane (a methoxy group-containing methylsiloxane oligomer) was added, and the mixture was mixed at room temperature for 20 minutes and then mixed at room temperature for 15 minutes under reduced pressure to obtain Composition 5 (Step [ii]).

[0055] [Comparative Example 3] In the production method of Example 1, instead of using 3.4 parts by mass of a mixture (condensation catalyst) prepared by uniformly mixing 0.7 part by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid in advance in step [i], Composition 6 was obtained in the same manner as in Example 1 except that 0.7 part by mass of calcium 2-ethylhexanoate was used.

[0056] [Comparative Example 4] In the production method of Example 1, instead of using 3.4 parts by mass of a mixture (condensation catalyst) prepared by uniformly mixing 0.7 part by mass of calcium 2-ethylhexanoate and 2.7 parts by mass of 2-ethylhexanoic acid in advance in step [i], Composition 7 was obtained in the same manner as in Example 1 except that 2.7 parts by mass of 2-ethylhexanoic acid was used.

[0057] [Physical Property Evaluation Test] Each of the compositions immediately after preparation prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was extruded into a sheet having a thickness of 2 mm, exposed to air at 23°C and 50% RH, and then the physical properties (initial physical properties) of the cured product obtained by leaving the sheet in the same atmosphere for 7 days were measured in accordance with JIS K-6249. The hardness of the cured product was measured using a durometer A hardness tester of JIS K-6249. The results are shown in Table 1.

[0058]

Table 1

[0059] From the results in Table 1, in Examples 1 to 3 and Comparative Example 1, the reactivity was good, curing occurred rapidly, and rubber elasticity was exhibited. In Comparative Example 2, curing was confirmed, but due to low catalyst activity, the strength and elongation of the cured product were low, and white precipitates were observed in the cured product. In Comparative Examples 3 and 4, the prepared compositions could not be cured.

[0060] The sheets prepared in Examples 1 to 3 and Comparative Example 1 and obtained by the same procedure as above were placed in a constant temperature bath at 150°C for 10 days or left in a UV irradiator (sterilization lamp TUV-15W manufactured by PHLIPS, irradiation conditions: wavelength 253.7 nm) for 7 days, and the color change of the sheets was visually observed. The results are shown in Table 2.

[0061]

Table 2

[0062] From the results in Table 2, no discoloration was observed in Examples 1 to 3 even after long-term storage at 150°C or long-term UV irradiation. On the other hand, in Comparative Example 1, yellowing (discoloration) was confirmed under any conditions.

Claims

1. A method for producing a room-temperature curable organopolysiloxane composition, comprising the following components (A) to (D): (A) Organopolysiloxane having silanol groups blocked at both ends of the molecular chain: 100 parts by mass, (B) A condensation catalyst composed of a mixture of a carboxylic acid and a metal salt of the same or different carboxylic acid as the carboxylic acid, wherein the mixing ratio of the carboxylic acid and the metal carboxylate is 1:99 to 50:50 by mass ratio of the metal carboxylate to the carboxylic acid: 0.01 to 30 parts by mass, (C) A hydrolyzable organosilane compound and / or its partial hydrolysis condensate (excluding the case where the number of hydrolyzable groups bonded to the silicon atoms in the molecule is 1): 0.1 to 30 parts by mass, and (D) Filler: 1 to 1,000 parts by mass, [i] A step of mixing component (A) with part or all of component (C) in the presence of component (B) to block the silanol groups at both ends of the molecular chain of the organopolysiloxane of component (A) with hydrolyzable silyl groups, and then, [ii] A step of mixing the remaining part of component (C) and component (D) into the reaction mixture obtained by mixing and reacting part or all of components (A), (B) and (C) obtained in step [i]. A method for producing a room-temperature curable organopolysiloxane composition, characterized by comprising the above steps.

2. In step [ii], further, (E) A curing catalyst other than component (B): 0.001 to 15 parts by mass based on 100 parts by mass of component (A), and (F) An adhesion promoter: 0.1 to 30 parts by mass based on 100 parts by mass of component (A) The method for producing a room-temperature curable organopolysiloxane composition according to claim 1, wherein at least one selected from the above is mixed.

3. The method for producing a room-temperature curable organopolysiloxane composition according to claim 1 or 2, comprising a step of adding a basic substance to the reaction mixture obtained by mixing and reacting part or all of components (A), (B) and (C) after step [i] to neutralize the reaction mixture.

Images