Method for curing condensation-curable organopolysiloxane composition, and method for promoting heat curing of condensation-curable organopolysiloxane composition

Abstract

To provide a curing method and a heat curing promotion method for a condensation-curable organopolysiloxane composition whose curing is promoted by heating and which is particularly excellent in deep curing and adhesion development.SOLUTION: A condensation-curable organopolysiloxane composition comprises: (A) a predetermined silanol group-containing diorganopolysiloxane component; (B) a crosslinking agent, which is a hydrolyzable silane represented by general formula (2) in the figure and / or a partial hydrolysate thereof, such that the content of the (B) component is 0.1 to 40 pts.mass per 100 pts.mass of the (A) component; and (C) an organic compound with at least one primary amino group per molecule, which is added such that the content of the primary amino groups of the (C) component is 0.001 to 1 mol per 100 g of the (A) component.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for curing a condensation-curable organopolysiloxane composition and a method for accelerating the heat cure of a condensation-curable organopolysiloxane composition. [Background technology]

[0002] Condensation-curing organopolysiloxane compositions (silicone rubber compositions) that crosslink when exposed to moisture are easy to handle and have excellent heat resistance, adhesion, and electrical properties, so they are used in a variety of fields, such as sealing materials for building materials and adhesives in the electrical and electronic fields. These condensation-curing organopolysiloxane compositions have the problem that they are poor in deep curing because they crosslink when exposed to moisture, and to improve this problem, one-component materials that reduce the amount of crosslinking agent to the minimum to improve the crosslinking rate by hydrolysis, and two-component materials in which the crosslinking agent and curing agent are packaged separately are known.

[0003] However, the above-mentioned one-liquid type condensation curing organopolysiloxane composition only has a fast curing speed from the surface, and a certain amount of time is required for deep curing. Although the two-liquid type condensation curing organopolysiloxane composition has relatively excellent deep curing properties, it has the disadvantage that it takes a long time to completely cure compared to the addition curing type organopolysiloxane composition. Furthermore, in the case of the two-liquid type condensation curing organopolysiloxane composition, in order to completely cure to the deep part, it is necessary to strictly specify the amount of crosslinking agent and curing agent to be added, or to add water as a deep curing agent.

[0004] In order to solve the above problems, the present inventors proposed a room temperature fast curing organopolysiloxane composition that contains an organic compound having a C=O group and an organic compound having an NH2 group for diorganopolysiloxane (see, for example, Patent Document 1 (Japanese Patent No. 2811134)). This technology utilizes water that is by-produced in the ketimine-forming reaction between the C=O group and the NH2 group in the composition to improve deep curing properties. However, the composition described in the above Patent Document 1 is of a room temperature curing type, and therefore does not have sufficient deep curing properties.

[0005] On the other hand, when a condensation curing type organopolysiloxane composition is heated to activate the crosslinking reaction and improve the deep curing property, when a one-component type is heated, the water required for the crosslinking reaction is not generated in the deep part, so it is difficult to improve the deep curing property. In addition, when a two-component type that cures by dealcoholization is heated, there is a problem that reversion occurs when heated, resulting in poor curing. Furthermore, when a two-component type that contains water as a deep curing agent is heated, there is a problem that the water before the reaction evaporates and bubbles are generated in the cured product.

[0006] In order to solve the above problems, Patent Document 2 (Japanese Patent No. 4743511) has discovered that deep curing properties can be improved by generating water through a reaction between a ketone compound produced from a condensation-curable organopolysiloxane composition and a compound having an amino group, and then heating the composition. However, further improvements in curability and adhesion expression are required in order to improve productivity.

[0007] Addition-curing organopolysiloxane compositions have excellent deep curing properties, but have the drawback that the curing catalyst in the composition is poisoned, limiting the working environment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 2811134 [Patent Document 2] Patent No. 4743511 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for curing a condensation-curable organopolysiloxane composition in which curing is accelerated by heating more than conventional methods, and which is particularly excellent in deep curing properties and adhesion development, and a method for accelerating the heat curing of a condensation-curable organopolysiloxane composition. [Means for solving the problem]

[0010] In view of the above circumstances, the present inventors have conducted extensive research and found that in a condensation curing organopolysiloxane composition in which curing proceeds gradually from the surface in contact with atmospheric moisture (moisture) toward the inside, water required for condensation curing is not added from the outside, but the cyclic ketone compound generated (released) when a specific crosslinking agent of component (B) that comes into contact with the atmosphere on the composition surface crosslinks with a silanol group in component (A) by hydrolysis and condensation is heated to a predetermined temperature, and the ketimine reaction with the amino compound of component (C) is promoted, and water is generated more quickly inside the composition, so that the composition is cured not only from the surface but also from the inside, and the fast curing property is improved (i.e., curing by heating is promoted) more than that of a conventional fast-curing condensation curing organopolysiloxane composition using a ketimine reaction, and furthermore, not only deep curing property but also adhesion development property can be developed, and thus the present invention has been completed. In addition, since the present invention is a thermosetting composition that activates the crosslinking reaction by heating, there is no catalyst poisoning like in addition curing compositions, and deep curing property and adhesion development property can be improved.

[0011] Accordingly, the present invention provides the following method for curing a condensation-curable organopolysiloxane composition and method for accelerating the heat cure of a condensation-curable organopolysiloxane composition. [1] (A) Formula (1): HO-(SiR 1 2O) a -H (1) (In the formula, R 1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1may be the same or different groups. a is an integer of 10 or more. Organopolysiloxane represented by the formula: 100 parts by mass, (B) the following general formula (2): [ka] (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number from 1 to 8, and m is 3 or 4. and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass, (C) an organic compound having at least one primary amino group per molecule: an amount such that the amount of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of organopolysiloxane, component (A); A method for curing a condensation-curable organopolysiloxane composition comprising the step of heating the condensation-curable organopolysiloxane composition to 50 to 150°C. [2] The method for curing a condensation-curable organopolysiloxane composition according to [1], wherein the hydrolyzable organosilane compound and / or its partial hydrolysis condensate, component (B), is one that releases a cyclic ketone compound upon hydrolysis. [3] The method for curing a condensation-curable organopolysiloxane composition according to [1] or [2], wherein the hydrolyzable organosilane compound of component (B) is a hydrolyzable organosilane compound represented by the following general formula (3): [ka] (In the formula, R 3 is a methyl group, a vinyl group, or a phenyl group, and m is 3 or 4. [4] The method for curing a condensation-curable organopolysiloxane composition according to any one of [1] to [3], further comprising: (D) 0.01 to 10 parts by mass of a curing catalyst per 100 parts by mass of the component (A). [5] The method for curing a condensation-curable organopolysiloxane composition according to any one of [1] to [4], wherein the curing catalyst (D) is at least one selected from the group consisting of tin catalysts, titanium catalysts, strong organic base catalysts, and organobismuth catalysts. [6] The method for curing a condensation-curable organopolysiloxane composition according to [4] or [5], wherein the boiling points of the components (A) to (D) are greater than 150°C. [7] (A) Formula (1): HO-(SiR 1 2O) a -H (1) (In the formula, R 1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more. and (B) a crosslinking agent, (B) component, The following general formula (2): [ka] (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number of 1 to 8, and m is 3 or 4.) and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass per 100 parts by mass of the component (A). And further, (C) an organic compound having at least one primary amino group per molecule: an amount such that the amount of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of organopolysiloxane, component (A); 2. A method for accelerating the heat cure of a condensation-curable organopolysiloxane composition, comprising adding [8] The method for accelerating heat cure of a condensation-curable organopolysiloxane composition according to [7], wherein the hydrolyzable organosilane compound of component (B) is a hydrolyzable organosilane compound represented by the following general formula (3): [ka] (In the formula, R 3 is a methyl group, a vinyl group, or a phenyl group, and m is 3 or 4. [9] The method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to [7] or [8], wherein component (C) is a silane coupling agent having an NH2 group.

[10] The method for accelerating the heat curing of a condensation curable organopolysiloxane composition according to any one of [7] to [9], further comprising 0.01 to 10 parts by mass of a curing catalyst (D) per 100 parts by mass of the component (A).

[11] The method for accelerating heat curing of a condensation-curable organopolysiloxane composition according to

[10] , wherein the boiling points of the components (A) to (D) are greater than 150°C.

[12] The method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to any one of [7] to

[11] , wherein the heat treatment is performed at 150° C. or less.

[13] The method for accelerating the heat curing of a condensation-curable organopolysiloxane composition according to any one of [7] to

[12] , wherein the condensation-curable organopolysiloxane composition is for use in an adhesive, a sealing agent, or a potting agent. Effect of the Invention

[0012] According to the present invention, it is possible to provide a method for curing a condensation-curable organopolysiloxane composition and a method for accelerating heat curing, which can improve the rapid curing property by heating and can also develop not only deep curing properties but also adhesion properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The method for curing the condensation-curable organopolysiloxane composition according to the present invention comprises the steps of: (A) Formula (1): HO-(SiR 1 2O) a -H (1) (In the formula, R1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more. Organopolysiloxane represented by the formula: 100 parts by mass, (B) the following general formula (2): [ka] (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number from 1 to 8, and m is 3 or 4. and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass, (C) an organic compound having at least one primary amino group per molecule: an amount such that the amount of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of organopolysiloxane, component (A); The method is characterized by comprising a step of heating a condensation-curable organopolysiloxane composition containing the above to 50 to 150°C. The method for accelerating the heat curing of a condensation-curable organopolysiloxane composition according to the present invention further comprises the steps of: (A) Formula (1): HO-(SiR 1 2O) a -H (1) (In the formula, R 1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more. and (B) a crosslinking agent, (B) component, The following general formula (2): [ka] (In the formula, R 2is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number of 1 to 8, and m is 3 or 4.) and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass per 100 parts by mass of the component (A). And further, (C) an organic compound having at least one primary amino group per molecule: an amount such that the amount of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of organopolysiloxane, component (A); The present invention is characterized in that

[0014] The term "heat curing acceleration method" refers to a method of accelerating the curing of a condensation curing organopolysiloxane composition by heating. Acceleration of curing by heating refers to accelerating the curing by hydrolysis and condensation reaction of the base polymer (organopolysiloxane) and crosslinking agent in the condensation curing organopolysiloxane composition by heating, and is capable of shortening the curing time until the overall curing, including deep (internal) curing, is completed by heating for a relatively short time (fast curing). Specifically, in the present invention, it refers to the curing time until the cohesive failure rate of the bonded part reaches 80% or more when the adherends are peeled off when the condensation curing organopolysiloxane composition is bonded to each other, such as aluminum, by heating. Also, the term "heat curing acceleration" is sometimes used to express such a characteristic.

[0015] [Condensation-curable organopolysiloxane composition] The condensation-curable organopolysiloxane composition, which is a characteristic feature of the present invention, will be described below. The condensation-curable organopolysiloxane composition of the present invention is intended to be heated for curing, and contains the following components (A) to (C) as essential components.

[0016] Among these, component (A) is a base oil (base polymer) used in the condensation curing type organopolysiloxane composition. Component (B) is a crosslinking agent (curing agent) that generates a cyclic ketone compound that undergoes a ketimine reaction with component (C) by hydrolysis. Therefore, it is not necessary to add a C=O compound as in the composition described in Patent Document 1. Component (C) undergoes a ketimine reaction with the cyclic ketone compound, and generates water as a by-product of the ketimine reaction in the composition. Since the cyclic ketone compound is highly reactive, the ketimine reaction with component (C) proceeds more effectively by heating (i.e., water is efficiently generated), and curing is accelerated by heating compared to the composition described in Patent Document 2 (excellent heat curing acceleration, i.e., excellent fast curing and deep curing by heating), and in particular excellent adhesion development as well as deep curing properties.

[0017] [Component (A)] The component (A) used in the condensation-curable organopolysiloxane composition of the present invention that is cured by heating is an organopolysiloxane represented by the following general formula (1). HO-(SiR 1 2O) a -H (1) (In the formula, R 1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more.

[0018] Component (A) is a linear diorganopolysiloxane having a main chain consisting of repeating diorganosiloxane units as shown in formula (1) and both molecular chain terminals blocked with hydroxyl groups (silanol groups) bonded to silicon atoms, preferably having a viscosity at 23°C of 20 to 1,000,000 mPa s, and serves as the main agent (base polymer) for the condensation-curable organopolysiloxane composition of the present invention that cures upon heating.

[0019] In the above formula (1), R 1is a halogen atom-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, and examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, nonyl, and decyl groups; cycloalkyl groups such as cyclohexyl groups; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and hexenyl groups; aryl groups such as phenyl and tolyl groups; and aralkyl groups such as benzyl and phenylethyl groups. Alternatively, examples of R include groups in which the hydrogen atoms of these hydrocarbon groups are partially substituted with halogen atoms such as chlorine, fluorine, and bromine, such as a trifluoropropyl group. 1 The halogen atom-substituted or unsubstituted monovalent hydrocarbon group of R is preferably one that does not contain an aliphatic unsaturated bond, and specifically, an alkyl group such as a methyl group, or an aryl group such as a phenyl group is more preferable, and a methyl group is particularly preferable. 1 may be the same group or different groups.

[0020] In the above formula (1), the difunctional diorganosiloxane unit (SiR 1 2O 2 / 2 The character a, which indicates the number of repetitions (or degree of polymerization) of (a), is an integer of 10 or more, preferably an integer of 50 to 2,000, more preferably an integer of 100 to 1,500, and particularly preferably an integer of 200 to 1,200. Note that since the organopolysiloxane of component (A) usually has a molecular weight distribution as a mixture of two or more types of molecules with different degrees of polymerization, it is sufficient for a to be a number within the above range as an average value.

[0021] In the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) in gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF) or the like as a developing solvent.

[0022] The organopolysiloxane of component (A) has a viscosity at 23°C of preferably 20 to 1,000,000 mPa·s, more preferably 100 to 300,000 mPa·s, even more preferably 1,000 to 200,000 mPa·s, and particularly preferably 10,000 to 100,000 mPa·s. If the viscosity of the organopolysiloxane is less than the lower limit (20 mPa·s), large amounts of components (B) and (C) described below are required, which may be economically disadvantageous. If the viscosity of the organopolysiloxane is more than the upper limit (1,000,000 mPa·s), workability decreases, which is not preferable.

[0023] The organopolysiloxane of the component (A) may use either a single type, or a combination of two or more types.

[0024] [(B) Component] The component (B) used in the condensation-curable organopolysiloxane composition of the present invention that is cured by heating is a hydrolyzable organosilane compound represented by the following general formula (2) and / or a partial hydrolysis condensate thereof, which is used as a crosslinking agent (curing agent) and is characterized in that it releases a cyclic ketone compound such as cyclobutanone or cyclopentanone as a leaving group (leaving substance) upon hydrolysis. In the present invention, the term "partial hydrolysis condensate" refers to an organosiloxane oligomer having 3 or more, preferably 4 or more, residual hydrolyzable groups in the molecule, which is produced by partial hydrolysis and condensation of the hydrolyzable organosilane compound. [ka] (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is an integer from 1 to 8, and m is 3 or 4.

[0025] In the above general formula (2), R 2is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms; 2 Examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, nonyl, and decyl, alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and hexenyl, aryl groups such as phenyl and tolyl, and aralkyl groups such as benzyl and phenylethyl. Among these, methyl, ethyl, vinyl, and phenyl groups are preferred, and methyl, vinyl, and phenyl groups are particularly preferred.

[0026] In the above general formula (2), n is an integer of 1 to 8, preferably an integer of 2 to 6, more preferably an integer of 2 to 4, and even more preferably 2 or 3. When n is 0, a cyclic structure is not formed. When n is an integer of 9 or more, the molecular weight of the hydrolyzable organosilane becomes large, making purification by distillation difficult and increasing the amount added to ensure storage stability, which is disadvantageous in terms of cost.

[0027] As mentioned above, m is 3 or 4. If this number is less than 3, rubber hardening by crosslinking reaction does not occur, making the compound unsuitable as a crosslinking agent for condensation-curable organopolysiloxane compositions.

[0028] In addition, the leaving group (leaving compound) generated by hydrolysis of the hydrolyzable organosilane compound represented by the above general formula (2) is a cyclic ketone compound such as cyclopropanone, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclononanone, cyclodecanone, etc., preferably cyclobutanone and cyclopentanone, more preferably cyclopentanone. There are no reports of cyclobutanone and cyclopentanone being harmful to human health, such as carcinogenicity or reproductive toxicity, or environmentally harmful, such as toxicity to aquatic organisms. In addition, cyclopentanone is mass-produced industrially, is easily available, and is highly cost-competitive, so it is also advantageous for producing the hydrolyzable organosilane compound of the component (B), as described below.

[0029] The hydrolyzable organosilane compound of component (B) can be produced, for example, by reacting a chlorosilane compound corresponding to the hydrolyzable organosilane compound represented by general formula (2) with a cyclic ketone compound in the presence of a catalyst and a basic substance (e.g., dehydrochlorination reaction). The reaction formula is, for example, represented by the following formula [1].

[0030] [ka] (In the formula, R 2 , n, and m are as defined above.)

[0031] Examples of the chlorosilane compound include the following. [ka]

[0032] Examples of the cyclic ketone compound include the following. [ka]

[0033] The amount of the cyclic ketone compound to be reacted with the chlorosilane compound is preferably 0.95 to 3.0 mol, more preferably 0.99 to 2.5 mol, and even more preferably 1.0 to 2.0 mol, per mol of chlorine atoms in the chlorosilane compound. If the amount of the cyclic ketone compound is too small, the reaction may not be completed, whereas if the amount of the cyclic ketone compound is too large, purification may take a long time, resulting in an increase in production time.

[0034] The catalyst used in the reaction includes monovalent or divalent metallic copper compounds, such as, but not limited to, copper chloride, copper bromide, copper iodide, copper sulfate, copper nitrate, copper carbonate, basic copper carbonate, copper formate, copper acetate, and copper butyrate.

[0035] The amount of catalyst (metallic copper compound) added is preferably 0.001 to 0.5 mol, more preferably 0.002 to 0.2 mol, and even more preferably 0.003 to 0.1 mol, per mol of the chlorosilane compound. If the amount of catalyst added is too small, the reaction may not be completed, whereas if the amount of catalyst added is too large, it is disadvantageous in terms of cost.

[0036] The basic substance used in the reaction may be a basic substance having low nucleophilicity, such as trimethylamine, triethylamine, tripropylamine, tributylamine, urea, diazabicycloundecene, diazabicyclononene, etc. Among these, trimethylamine, triethylamine, and tributylamine are preferred, and triethylamine is particularly preferred.

[0037] The amount of the basic substance added is preferably 0.95 to 2.5 mol, more preferably 0.99 to 2.0 mol, and even more preferably 1.0 to 1.5 mol, per mol of chlorine atoms in the chlorosilane compound. If the amount of the basic substance added is small, the reaction may not be completed, whereas if the amount of the basic substance added is too large, it is economically disadvantageous.

[0038] A commonly used solvent may be used in the production of the hydrolyzable organosilane compound of component (B). Examples of the solvent include organic solvents such as aromatic hydrocarbons, such as toluene, xylene, and benzene; aliphatic hydrocarbons, such as pentane, hexane, heptane, nonane, octane, and decane; ethers, such as dimethyl ether, methyl ethyl ether, tetrahydrofuran, and dioxane; halogenated hydrocarbons, such as perchloroethane, perchloroethylene, trichloroethane, chloroform, and carbon tetrachloride; amides, such as dimethylformamide; and esters, such as ethyl acetate, methyl acetate, and butyl acetate.

[0039] The amount of the solvent used is not particularly limited, but is usually in the range of 10 to 500 parts by mass, preferably 30 to 400 parts by mass, and more preferably 50 to 300 parts by mass, per 100 parts by mass of the cyclic ketone compound used.

[0040] The reaction conditions of the chlorosilane compound and the cyclic ketone compound are usually 0 to 120°C, preferably 0 to 100°C, at which the chlorosilane compound is dropped into the cyclic ketone compound, and the reaction is carried out at 50 to 120°C, preferably 60 to 100°C, for 1 to 48 hours, more preferably 3 to 30 hours. If the reaction temperature is too low, the reaction may not be completed, and if the reaction temperature is too high, the product may become significantly colored. If the reaction time is too short, the reaction may not be completed, and if the reaction time is too long, the reaction time is disadvantageous to productivity.

[0041] After the reaction is complete, the product can be purified by distillation under reduced pressure. The degree of reduction is preferably 1×10 -5 ~3,000 Pa, more preferably 1×10 -5 The pressure during the purification is preferably 100 to 250° C., and more preferably 120 to 230° C. If the pressure during the purification (degree of reduction in pressure) is too high, distillation may become difficult. If the temperature during the purification is too low, purification by distillation may become difficult, and if it is too high, coloration or decomposition of the reaction product may occur.

[0042] Specific examples of the hydrolyzable organosilane compound of component (B) include those represented by the following formula: In this case, Me represents a methyl group. [ka]

[0043] The component (B) is preferably a novel organosilicon compound (hydrolyzable organosilane compound) that is particularly represented by the following general formula (3) and that eliminates cyclopentanone as a leaving group (eliminating compound) generated by hydrolysis. [ka] (wherein m is the same as above, and R 3 is a methyl, vinyl or phenyl group.)

[0044] As mentioned above, m is 3 or 4. If this number is less than 3, rubber hardening by crosslinking reaction does not occur, making the compound unsuitable as a crosslinking agent for condensation-curable organopolysiloxane compositions.

[0045] The hydrolyzable organosilane compound used in the present invention can be produced, for example, by reacting a chlorosilane compound with cyclopentanone in the presence of a catalyst and a basic substance (for example, dehydrochlorination reaction). This reaction formula is, for example, represented by the following formula [2]. [ka] (In the formula, R 3 , m is as defined above).

[0046] Examples of the chlorosilane compound include the following. [ka]

[0047] The amount of cyclopentanone added to react with the chlorosilane compound is preferably 0.95 to 3.0 mol, more preferably 0.99 to 2.5 mol, and even more preferably 1.0 to 2.0 mol, per mol of chlorine atoms in the chlorosilane compound. If the amount of cyclopentanone added is small, the reaction may not be completed, whereas if the amount of cyclopentanone added is too large, purification takes a long time, increasing the production time.

[0048] The basic substance used in the reaction may be a basic substance having low nucleophilicity, such as trimethylamine, triethylamine, tripropylamine, tributylamine, urea, diazabicycloundecene, diazabicyclononene, etc. Among these, trimethylamine, triethylamine, and tributylamine are preferred, and triethylamine is particularly preferred.

[0049] The amount of the basic substance added is preferably 0.95 to 2.5 mol, more preferably 0.99 to 2.0 mol, and even more preferably 1.0 to 1.5 mol, per mol of chlorine atoms in the chlorosilane compound. If the amount of the basic substance added is small, the reaction may not be completed, whereas if the amount of the basic substance added is too large, it is economically disadvantageous.

[0050] Examples of catalysts used in the reaction include monovalent or divalent metallic copper compounds and metallic silver compounds, such as copper chloride, copper bromide, copper iodide, copper sulfate, copper nitrate, copper carbonate, basic copper carbonate, copper formate, copper acetate, copper butyrate, silver chloride, silver iodide, silver sulfate, silver nitrate, silver carbonate, basic silver carbonate, silver formate, silver acetate, and silver butyrate, but are not limited to these.

[0051] The amount of catalyst (metallic copper compound, metallic silver compound) added is preferably 0.001 to 0.5 mol, more preferably 0.002 to 0.2 mol, and even more preferably 0.003 to 0.1 mol, per mol of the chlorosilane compound. If the amount of catalyst added is too small, the reaction may not be completed, whereas if the amount of catalyst added is too large, it is disadvantageous in terms of cost.

[0052] A commonly used solvent may be used in the production of the hydrolyzable organosilane compound used in the present invention, and examples of such organic solvents include aromatic hydrocarbons such as toluene, xylene, benzene, etc.; aliphatic hydrocarbons such as pentane, hexane, heptane, nonane, octane, decane, etc.; ethers such as dimethyl ether, methyl ethyl ether, tetrahydrofuran, dioxane, etc.; halogenated hydrocarbons such as perchloroethane, perchloroethylene, trichloroethane, chloroform, carbon tetrachloride, etc.; amides such as dimethylformamide, etc.; and esters such as ethyl acetate, methyl acetate, butyl acetate, etc.

[0053] The amount of the solvent used is not particularly limited, but is usually in the range of 10 to 500 parts by mass, preferably 30 to 400 parts by mass, and more preferably 50 to 300 parts by mass, per 100 parts by mass of cyclopentanone used.

[0054] The reaction conditions of the chlorosilane compound and cyclopentanone are usually 0 to 130°C, preferably 20 to 120°C, at which the chlorosilane compound is dropped into cyclopentanone, and the reaction is carried out at 50 to 140°C, preferably 60 to 130°C, for 0.5 to 48 hours, preferably 1 to 30 hours. If the reaction temperature is too low, the reaction may not be completed, and if the reaction temperature is too high, the product may become significantly colored. If the reaction time is too short, the reaction may not be completed, and if the reaction time is too long, the reaction may be disadvantageous to productivity.

[0055] After the reaction is complete, the product can be purified by distillation under reduced pressure. The degree of reduction is preferably 1×10 -5 ~3,000 Pa, more preferably 1×10 -5 The pressure during the purification is preferably 100 to 250° C., and more preferably 120 to 230° C. If the pressure during the purification (degree of reduction in pressure) is too high, distillation may become difficult. If the temperature during the purification is too low, purification by distillation may become difficult, and if it is too high, coloration or decomposition of the reaction product may occur.

[0056] Specific examples of the hydrolyzable organosilane compound used in the present invention include those represented by the following formula: [ka]

[0057] If an organosilicon compound (hydrolyzable organosilane compound) that releases cyclopentanone as the leaving group (leaving compound) generated by such hydrolysis is used as a crosslinking agent (curing agent) for a condensation thermosetting organopolysiloxane composition, it is possible to obtain a cured product that has particularly fast curing properties and excellent rubber physical properties. Cyclopentanone is less harmful to the human body and the environment and is also a compound that has excellent biodegradability compared to methanol and 2-butanone oxime.

[0058] The hydrolyzable organosilane compound used in the present invention has cyclopentanone as the leaving group (leaving compound) generated by hydrolysis, and is particularly suitable for use as a crosslinking agent for condensation-curable organopolysiloxane compositions that are cured by heating.

[0059] When such a hydrolyzable organosilane compound is used as a crosslinking agent for a condensation-curable organopolysiloxane composition that is cured by heating, it is possible to impart higher safety and rapid curing properties.

[0060] The component (B) may use one type alone, or two or more types in combination. The amount of component (B) is 1 to 40 parts by mass, preferably 3 to 30 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is less than the lower limit of 1 part by mass, the shelf life may deteriorate when stored in a sealed container. If the amount of component (B) is more than the upper limit of 40 parts by mass, the curability of the condensation-curable organopolysiloxane composition that cures upon heating may decrease significantly, and the adhesiveness may also deteriorate.

[0061] [(C) component] Component (C) is an organic compound (amino group-containing organic compound (also called amino compound)) that has at least one primary amino group (-NH2 group) in one molecule, and generates water inside the composition by a ketimine reaction with a cyclic ketone compound that is generated (released) when the crosslinking agent of component (B) hydrolyzes and condenses with the silanol groups in component (A) to crosslink. That is, component (C) undergoes a dehydration condensation reaction (ketimine reaction) of the following reaction formula [3] with the cyclic ketone compound generated (released) by hydrolysis of component (B). [Cycloalkane residue]C=O + H2NR 5 → [Cycloalkane residue]C=NR 5 + H2O [3] (In the formula, R 5 is a given organic group.)

[0062] This reaction generates water in the composition which is necessary for the crosslinking reaction.

[0063] The amino group-containing organic compound used as component (C) can be any one that has at least one reactive amino group in one molecule.Specific organic compounds include amines such as methylamine, ethylamine, butylamine, ethylenediamine, and aniline; silane coupling agents having NH2 groups such as γ-aminopropyltriethoxysilane; and polymers and oligomers having NH2 groups, and these can be used alone or in combination of two or more.In particular, primary amine compounds and silane coupling agents having NH2 groups are preferred.

[0064] In addition, it is preferable to use, as the amino group-containing organic compound, one in which the carbon atom at the α-position of the amino group is a primary, secondary, or part of an aromatic ring, in order to reduce steric hindrance during the reaction with the ketone compound. If the carbon atom at the α-position is a normal tertiary carbon atom, the reactivity with the carbonyl group is poor, and the desired effect may not be obtained.

[0065] The amount of component (C) is such that the amount of primary amino groups (NH2 groups) in component (C) is 0.001 to 1 mole per 100 g of organopolysiloxane (A), and preferably 0.01 to 0.1 moles of primary amino groups (NH2 groups). If the amount of primary amino groups (NH2 groups) in component (C) is less than 0.001 moles, the improvement in heat curing acceleration (fast curing by heating and deep curing ability) is insufficient, and if it exceeds 1 mole, the obtained elastic cured product will not exhibit the desired physical properties (will be too hard).

[0066] [(D) component] The condensation-curable organopolysiloxane composition of the present invention that cures upon heating may optionally contain a curing catalyst (D).

[0067] As the curing catalyst of component (D), any metallic or non-metallic condensation catalyst that has conventionally been used as a curing accelerator for condensation-curable organopolysiloxane compositions can be used. For example, dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, dimethyltin dimethoxide, dimethyltin diacetate, and other organic tin compounds (tin catalysts), tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, dimethoxytitanium diacetylacetonate, titanium diisopropoxybis(ethylacetoacetate), and other organic titanium compounds (titanium catalysts), triethylamine, hexylamine, tetramethylguanidine, γ-tetramethylguanidylpropyltrimethoxysilane, and other amine compounds and salts thereof (organic strong base catalysts), bismuth tris(2-ethylhexanoate), bismuth tris(neodecanoate), and other organic bismuth compounds and mixtures thereof (organic bismuth catalysts), and the like can be mentioned. At least one of these, that is, one type can be used alone, or two or more types can be used in combination.

[0068] In the present invention, among the above catalysts, when any of the titanium catalyst, the organic strong base catalyst, and the organic bismuth catalyst is blended, the same curability and cured product performance are exhibited as when a tin catalyst is blended. Therefore, from the viewpoint of environmental protection, it is preferable to blend a titanium catalyst, an organic strong base catalyst, or an organic bismuth catalyst without blending a tin catalyst.

[0069] When component (D) is blended, the blending amount is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, and even more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of component (A). If the blending amount of component (D) is less than the lower limit of 0.01 parts by mass, the catalytic effect may not be obtained, whereas if the blending amount exceeds the upper limit of 10 parts by mass, the storage stability of the composition may be poor.

[0070] [Other ingredients] In addition to the above components (A) to (C), the condensation-curable organopolysiloxane composition of the present invention that cures upon heating can contain various additives, so long as the rapid curing and deep curing properties under heat are not impaired. Here, it is necessary to select and use various optional additives within a range that does not inhibit the reaction of the above reaction formula [3].

[0071] Examples of such compounding agents include organic compounds having a C=O group, such as octanone and cyclohexanone; fillers such as fumed silica, precipitated silica, quartz powder, carbon powder, talc, bentonite, magnesium carbonate, and other fillers; fibrous fillers such as glass fiber, carbon fiber, and organic fiber; colorants such as pigments and dyes; heat resistance improvers such as red iron oxide and cerium oxide; cold resistance improvers; rust inhibitors; adhesion improvers such as γ-glycidoxypropyltrimethoxysilane; and liquid reinforcing agents such as network polysiloxanes composed of triorganosiloxy units and SiO2 units, and these can be added in normal amounts as needed.

[0072] [Form of composition] The condensation-curable organopolysiloxane composition of the present invention cures as a result of the reaction of components (A) to (C) during use. Therefore, the composition must be in a form in which components (A) to (C) each exist in an unreacted state prior to use.

[0073] For example, the composition used in the present invention may be in the form of a two-liquid package with component (A) and component (B) as agent X and component (A) and component (C) as agent Y, and handling is facilitated by mixing agent X:agent Y at a ratio of 1:1 when used. Also, the composition may be in the form of a two-liquid package with component (A) and component (C) as agent X and component (A) and component (B) as agent Y.

[0074] In addition, as a one-liquid type, the above components (A) to (C) and, if necessary, the above compounding agents may be further mixed together, and the mixture may be uniformly mixed in a dry (anhydrous) atmosphere and packaged so as to prevent moisture from being mixed in. In this case, in order to ensure the storage stability of the packaged product, the component C may be encapsulated to prevent hardening before use. The component (C) may also be contained in microcapsules that are destroyed by the heat during thermal curing.

[0075] The method for curing the condensation curable organopolysiloxane composition of the present invention includes a step of heating the condensation curable organopolysiloxane composition, and the heating temperature is 50 to 150° C., preferably 70 to 120° C. If the heating temperature is less than 50° C., the crosslinking reaction by component (B) and the ketimine reaction between the cyclic ketone compound generated (released) from component (B) and the amino compound of component (C) do not proceed sufficiently, and if the heating temperature exceeds 150° C., each component may volatilize. The heating time can be adjusted depending on the process, and is, for example, 10 minutes to 4 hours, preferably 30 minutes to 2 hours. The method for curing the condensation-curable organopolysiloxane composition of the present invention preferably includes a curing step for promoting the curing of the condensation-curable organopolysiloxane composition after the above-mentioned heating. Curing is preferably carried out by leaving the composition in an atmospheric room temperature (23±15°C) environment. According to the present invention, the above-mentioned heating significantly shortens the curing time compared to the case where heating is not performed.

[0076] In addition, it is preferable that the boiling points (under 1 atmosphere) of the components (A) to (D) are each above 150°C. In this way, each component is less likely to volatilize, and the curing temperature can be increased to further promote curing. In addition, in the case where the organopolysiloxane of the component (A) is a polymer having a molecular weight distribution and therefore does not have a clear boiling point, it is sufficient that it does not lose weight (does not contain volatile components) when heated at 150°C. In addition, the boiling point referred to here is the boiling temperature at 1 atmosphere.

[0077] The method for accelerating the heat curing of a condensation curable organopolysiloxane composition of the present invention is characterized in that, in a condensation curable organopolysiloxane composition containing the above-mentioned component (A) and a crosslinking agent (B), the component (B) is a hydrolyzable silane represented by the above-mentioned general formula (2) and / or a partial hydrolyzate thereof (amount blended: 0.1 to 40 parts by mass per 100 parts by mass of the component (A)), and further, (C) an organic compound having at least one primary amino group per molecule (amount blended: an amount such that the primary amino group in the component (C) is 0.001 to 1 mole per 100 g of the component (A)). This improves the heat curing acceleration properties (i.e., fast curing and deep curing by heating) of the condensation curable organopolysiloxane composition.

[0078] As described above, according to the present invention, the heat curing acceleration properties of the condensation-curable organopolysiloxane composition are improved, and therefore this condensation-curable organopolysiloxane composition is preferably used for an adhesive, sealant, or potting agent, and can be particularly suitably used for electrical and electronic sealing agents, automotive oil seals, adhesives, potting agents, and the like, which are in high demand for process streamlining. EXAMPLES

[0079] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" refer to parts by mass and % by mass unless otherwise specified. The viscosity is a value measured at 23°C using a rotational viscometer according to the method specified in JIS Z 8803.

[0080] A condensation-curable organopolysiloxane composition was prepared as follows. (Composition 1) Component (A) is a polydimethylsiloxane having a viscosity of 5,000 mPa s (in the above general formula (1), R 1 = methyl group, a = about 400 (average value), confirmed to have no weight loss when heated at 150 ° C.) and 10 parts by mass of fumed silica were mixed under reduced pressure (0.08 MPa or less, the same applies below) for 30 minutes. After mixing under reduced pressure, 2.7 parts by mass of a compound represented by the following formula (saturated vapor pressure at 140 ° C. is 0.4 kPa, boiling point is over 150 ° C.) as component (B), 2.21 parts by mass (0.01 moles for 2.21 g) of γ-aminopropyltriethoxysilane (boiling point: 217 ° C.) as component (C), and 0.5 parts by mass of γ-(N,N,N',N'-tetramethylguanidyl)propyltrimethoxysilane (saturated vapor pressure at 135 ° C. is 1.5 kPa, boiling point is over 150 ° C.) as a compounding agent (condensation catalyst) were added, and mixed under reduced pressure for 15 minutes to obtain composition 1. [ka]

[0081] (Composition 2) Composition 2 was prepared in the same manner as in Example 1, except that the component (B) in composition 1 was changed to 2.0 parts by mass of vinyltriisopropenoxysilane (boiling point: 198° C.).

[0082] (Composition 3) Composition 3 was prepared in the same manner as in Example 1, except that the (B) component of composition 1 was changed to 2.8 parts by mass of vinyltrimethylethylketoximesilane (saturated vapor pressure at 153°C is 0.8 kPa, and boiling point is over 150°C) and the compounding agent (condensation catalyst) was changed to 0.1 parts by mass of dioctyltin dineodecanoate (boiling point: over 200°C).

[0083] (Evaluation method) Each composition was applied to two aluminum substrates with a width of 25 mm and a length of 50 mm, with a bonding area of ​​2.5 mm. 2 A shear adhesion test specimen was prepared by sandwiching the specimen so that the adhesive thickness was 1 mm, and after holding the specimen in the air at a prescribed heating temperature for 1 hour and then curing the specimen for a prescribed time at 23°C / 50% RH, a tensile shear failure test was carried out in accordance with the method prescribed in JIS K 6249 to confirm the cohesive failure rate at the adhesive portion. Here, the heating temperature was 23°C (no heating, left at room temperature), and after heating to 50°C, 70°C, and 120°C, and the curing time at 23°C / 50% RH was 24 hours, 38 hours, 48 ​​hours, 62 hours, 72 hours, and 96 hours, and the cohesive failure rate of each shear adhesion test specimen was evaluated. The results obtained for the Examples are shown in Table 1, and the results obtained for the Comparative Examples are shown in Table 2. In the table, the notation "-" in the evaluation of the cohesive failure rate means that the cohesive failure rate could not be evaluated because the sample was not yet cured.

[0084] [Table 1]

[0085] [Table 2]

[0086] As is clear from Table 1, in Example 1, the onset of cohesive failure rate (i.e., the start of curing) was accelerated by heating compared to 23°C (no heating), and further the curing time until the cohesive failure rate reached 100% was shortened. It is therefore clear that not only was the rapid curing property by heating improved, but also that deep curing property and adhesion expression were excellent. In Comparative Example 1 in Table 2 (composition 2 which does not use a compound that eliminates a cyclic ketone by hydrolysis (component (B) of the present invention) as a crosslinking agent), a curing time of 48 hours was required for the cohesive failure rate to reach 100%, even at a heating temperature of 120°C, which is the temperature at which curing is most accelerated, and this was 24 hours longer than in Example 1 (cohesive failure rate of 100% after a curing time of 24 hours). Moreover, in Comparative Example 2 (composition 3), the result of the cohesive failure rate did not depend on the heating temperature (i.e., curing was not accelerated even by heating), and in both cases a curing time of 96 hours was required for the cohesive failure rate to reach 100%. As a result of the above, it was found that in order to promote the curing of the condensation-curable organopolysiloxane composition by heating, the component (B) of the present invention (the hydrolyzable silane represented by the above general formula (2) and / or its partial hydrolyzate) and the component (C) (the above amino group-containing organic compound) are necessary as composition components.

Claims

1. (A) a compound represented by the following general formula (1): HO-(SiR 1 2 O) a -+ (1) (In the formula, R 1 is a halogen-substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more. Organopolysiloxane represented by the formula: 100 parts by mass, (B) a compound represented by the following general formula (2): 【Chemistry 1】 (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number from 1 to 8, and m is 3 or 4. and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass, (C) an organic compound having at least one primary amino group per molecule: an amount such that the amount of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of the organopolysiloxane of component (A); The present invention relates to a method for curing a condensation-curable organopolysiloxane composition, the method comprising the step of heating the condensation-curable organopolysiloxane composition to a temperature of 50 to 150°C.

2. 2. A method for curing a condensation-curable organopolysiloxane composition according to claim 1, wherein the hydrolyzable organosilane compound and / or partial hydrolysis condensate thereof, component (B), is one which releases a cyclic ketone compound upon hydrolysis.

3. 2. A method for curing a condensation-curable organopolysiloxane composition according to claim 1, wherein the hydrolyzable organosilane compound of component (B) is a hydrolyzable organosilane compound represented by the following general formula (3): 【Chemistry 2】 (In the formula, R 3 is a methyl group, a vinyl group or a phenyl group, and m is 3 or 4.

4. 2. The method for curing a condensation-curable organopolysiloxane composition according to claim 1, further comprising: (D) 0.01 to 10 parts by weight of a curing catalyst per 100 parts by weight of component (A).

5. 5. The method for curing a condensation-curable organopolysiloxane composition according to claim 4, wherein the curing catalyst (D) is at least one catalyst selected from the group consisting of tin catalysts, titanium catalysts, strong organic base catalysts, and organobismuth catalysts.

6. 5. The method for curing a condensation-curable organopolysiloxane composition according to claim 4, wherein the boiling points of components (A) to (D) are greater than 150°C.

7. (A) a compound represented by the following general formula (1): HO-(SiR 1 2 O) a -+ (1) (In the formula, R 1 are independently halogen-substituted or unsubstituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, and each R 1 may be the same or different groups. a is an integer of 10 or more. Organopolysiloxanes represented by the formula: In the condensation-curable organopolysiloxane composition containing a crosslinking agent (B), The component (B), The following general formula (2): 【Chemistry 3】 (In the formula, R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, n is a positive number from 1 to 8, and m is 3 or 4.) and / or a partial hydrolyzate thereof: 0.1 to 40 parts by mass per 100 parts by mass of component (A). And further, A method for accelerating the heat cure of a condensation-curable organopolysiloxane composition, comprising adding (C) an organic compound having at least one primary amino group per molecule in an amount such that the number of primary amino groups in component (C) is 0.001 to 1 mole per 100 g of the organopolysiloxane of component (A).

8. 8. A method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 7, wherein the hydrolyzable organosilane compound of component (B) is a hydrolyzable organosilane compound represented by the following general formula (3): 【Chemistry 4】 (In the formula, R 3 is a methyl group, a vinyl group or a phenyl group, and m is 3 or 4.

9. The component (C) is NH 2 9. A method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 7 or 8, wherein the silane coupling agent has a group.

10. 9. The method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 7 or 8, further comprising 0.01 to 10 parts by mass of a curing catalyst (D) per 100 parts by mass of component (A).

11. 11. The method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 10, wherein the boiling points of components (A) to (D) are greater than 150°C.

12. 9. A method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 7 or 8, wherein the heat treatment is carried out at a temperature of 150° C. or less.

13. 9. The method for accelerating the heat cure of a condensation-curable organopolysiloxane composition according to claim 7 or 8, wherein the condensation-curable organopolysiloxane composition is for use as an adhesive, a sealing agent or a potting agent.

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