Room temperature-curable organopolysiloxane composition, cured product thereof, and article

Abstract

To provide a room temperature-curable organopolysiloxane composition which can provide a silicone rubber cured product having self-repairing property.SOLUTION: A room temperature-curable organopolysiloxane composition comprises (A) 100 pts.mass of an organopolysiloxane represented by a formula (1), (in the formula, R1 is each independently a monovalent 1-10C hydrocarbon group, R2 is each independently a hydrogen atom or an unsubstituted or substituted monovalent 1-6C hydrocarbon group, a is an integer of 1-10, and b is an integer of 1-200, each of x and y is an integer of 1-50, and n is an integer of 1-10, in addition, each repeating unit shown in parentheses with x and y may be randomly arranged), (B) 0.1-40 pts.mass of a hydrolyzable organosilane compound having three or more hydrolyzable groups bonded to silicon atoms in a molecule and / or a partially hydrolyzed condensate thereof, and (C) 0.01-10 pts.mass of a curing catalyst.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a condensation-cure, room-temperature-curable organopolysiloxane composition that crosslinks (cures) through a hydrolysis-condensation reaction in the presence of atmospheric moisture (water) at room temperature (23°C±15°C), and in particular to a room-temperature-curable organopolysiloxane composition that gives a silicone rubber cured product (elastomeric organopolysiloxane cured product) that has self-repairing properties, as well as to the cured product (silicone rubber cured product) and various articles containing the cured product. [Background technology]

[0002] Room-temperature-curable organopolysiloxane compositions that cure to form silicone rubber at room temperature have long been known and have been widely used in industry. Known mechanisms by which room-temperature-curable organopolysiloxane compositions cure at room temperature include curing via a hydrosilylation addition reaction, radical curing via ultraviolet light, and curing via a condensation reaction between a hydrolyzable group bonded to a silicon atom and a hydroxyl group. Among these, room-temperature-curable organopolysiloxane compositions that cure via a condensation reaction have the advantage of being easily cured at room temperature and of being less susceptible to curing inhibition by impurities generated during hydrosilylation addition reactions and other reactions. For these reasons, they are widely used in fields such as automotive gaskets and sealing materials, construction sealants, and electrical and electronic components.

[0003] Cured silicone rubber products made from room-temperature-curable organopolysiloxane compositions that cure through a condensation reaction possess high heat resistance, chemical resistance, and weather resistance inherent to the silicone (siloxane structure). However, when the silicone rubber itself is damaged or broken, it is necessary to remove the damaged cured product and apply a new composition. Therefore, there is a demand for cured silicone rubber products with self-healing properties to reduce the effort required for repairs and extend the life of sealants.

[0004] Known self-healing polymers include urethane polymers, urea polymers (Non-Patent Documents 1 and 2), and amide polymers (Patent Document 1). These are technologies that impart self-healing properties (the property that when a cured product is damaged or broken, the damaged or broken parts are bonded together to form a contact surface, and the shape and / or physical properties are restored over time at a predetermined recovery rate) through hydrogen bonds derived from the urethane structure, urea structure, amide structure, etc. However, no conventional curable silicone polymer (organopolysiloxane) has a repeating unit in the main chain that exhibits hydrogen bonds strong enough to exhibit self-healing properties.

[0005] Furthermore, it has been reported that a solid random copolymer consisting of a repeating unit having a thiourea structure and a siloxane structure and a repeating unit having a thiourea structure but not containing a siloxane structure, exhibits self-repairing properties (recovery of tensile stress due to compression at a predetermined temperature) as a polymer with self-repairing properties (Patent Document 2). However, Patent Document 2 does not disclose whether a cured rubber (elastomer-like elastic body) three-dimensionally crosslinked using the random copolymer as a base polymer can exhibit self-repairing properties in terms of various rubber physical properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-091779 [Patent Document 2] International Publication No. 2023 / 085303

[0007] [Non-Patent Document 1] M. Hendrich, L. Lewerdomski, P. Vana. J. Polymer Science, Part A: Polymer Chemistry. 53, 2809-2819 (2015). [Non-patent document 2] E. D'Elia, S. Barg, N. Ni, VG Rocha, E. Saiz. Advanced Materials. 27, 4788-4794 (2015). Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a room-temperature-curable organopolysiloxane composition that uses, as a base polymer (main component), an organopolysiloxane having repeating thiourea bonds (thiourea structures) in the main chain, and that is capable of giving a silicone rubber cured product with self-repairing properties due to the strong hydrogen bonds derived from the thiourea bonds (thiourea structures); a cured product (silicone rubber cured product) with self-repairing properties obtainable by curing this composition; and various articles that contain the cured product. [Means for solving the problem]

[0009] As a result of extensive research conducted by the present inventors in order to achieve the above-mentioned object, they discovered that a room-temperature-curable organopolysiloxane composition containing, as a base polymer (main component), a linear diorganopolysiloxane having repeating thiourea bonds (thiourea structures) in the polymer main chain, as represented by the following general formula (1), can give a cured silicone rubber that exhibits high self-repairing properties at room temperature, leading to the completion of the present invention. [ka] (In the formula, R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups, and R 2 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and each R 2may be the same or different groups. a is an integer of 1 to 10, and b is an integer of 1 to 200. x and y are each an integer of 1 to 50, and n is independently an integer of 1 to 10. In addition, the repeating units shown in parentheses with x and y may be arranged randomly.

[0010] That is, the present invention provides the following room-temperature-curable organopolysiloxane compositions, cured products of the compositions, and various articles containing the cured products (automobile parts, automobile oil seals, electrical and electronic parts, building structures, civil engineering structures, adhesives, sealants, potting agents, coating agents, etc.). [1] (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1): [ka] (In the formula, R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups, and R 2 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and each R 2 may be the same or different groups. a is an integer of 1 to 10, and b is an integer of 1 to 200. x and y are each an integer of 1 to 50, and n is independently an integer of 1 to 10. In addition, the repeating units shown in parentheses with x and y may be arranged randomly. (B) a hydrolyzable organosilane compound having three or more silicon-bonded hydrolyzable groups in the molecule and / or a partial hydrolysis condensate thereof: 0.1 to 40 parts by mass, and (C) Curing catalyst: 0.01~10 parts by mass A room-temperature-curable organopolysiloxane composition comprising: [2] The room-temperature-curable organopolysiloxane composition according to [1], further comprising, as component (D), 0.01 to 5 parts by mass of a silane coupling agent represented by the following general formula (2) and / or a partial hydrolysis condensate thereof per 100 parts by mass of component (A): R 3 R 4 c Six 3-c (2) (In the formula, R 3 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one functional group (excluding a guanidyl group) containing one or more heteroatoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom. 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is a hydrolyzable group. c is 0, 1, or 2. [3] The room-temperature-curable organopolysiloxane composition according to [1] or [2], further comprising at least one inorganic filler as component (E). [4] A cured product obtained by curing the room-temperature-curable organopolysiloxane composition according to any one of [1] to [3]. [5] [4] An article having the cured product described in [4]. [Effects of the Invention]

[0011] The room-temperature-curable organopolysiloxane composition of the present invention crosslinks (cures) through a hydrolysis-condensation reaction to form a cured product that has self-repairing properties in a room temperature environment, and is therefore suitable for use as a variety of adhesives, sealing materials, potting agents, coating agents, etc. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. In this invention, viscosity is measured using a rotational viscometer in accordance with the method specified in JIS Z 8803. Unless otherwise specified, "room temperature" refers to a temperature of 23°C ± 15°C and a humidity of 50% RH ± 5% RH. Furthermore, "self-repairing" refers to the property of a cured silicone rubber obtained by curing a room-temperature-curable organopolysiloxane composition, whereby when the cured silicone rubber is damaged or broken, the damaged or broken parts are bonded together to form a contact surface, and the shape and / or physical properties (particularly mechanical properties such as tensile strength and elongation at break) are restored over time at a predetermined recovery rate.

[0013] [Component (A): Organopolysiloxane] Component (A) used in the room-temperature-curable organopolysiloxane composition of the present invention is a linear organopolysiloxane having repeating thiourea bonds (thiourea structures) in the main chain of the molecule represented by the following general formula (1): [ka] (In the formula, R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups, and R 2 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and each R 2 may be the same or different groups. a is an integer of 1 to 10, and b is an integer of 1 to 200. x and y are each an integer of 1 to 50, and n is independently an integer of 1 to 10. In addition, the repeating units shown in parentheses with x and y may be arranged randomly.

[0014] As shown in the general formula (1) above, component (A) is a diorganopolysiloxane having a main chain containing thiourea bond units (i.e., a diorganopolysiloxane structure [-(R 1 2SiO 2 / 2 )a-Si(R 1 )2-], each end of which has a thiourea structure (-NR 2-C(=S)-NR 2 a repeating unit having a linker structure in which an alkylene group -(CH2)n- is connected to both sides of the repeating unit (two in total)), and a silicone unit (i.e., a diorganopolysiloxane [(R 1 2SiO 2 / 2 )b]) and a repeating unit consisting only of (a) and (b)), and both molecular chain terminals are blocked with silyl groups having hydroxyl groups (silanol groups) bonded to silicon atoms, and this acts as the main component (base polymer) of the room-temperature-curable organopolysiloxane composition of the present invention. In the above formula (1), the arrangement of the repeating unit having two thiourea structures (thiourea bond unit) and the repeating unit consisting of diorganopolysiloxane (silicone unit) (the bonding of each repeating unit shown in parentheses with x and y) may be random.

[0015] In the above formula (1), R 1 R is an unsubstituted or substituted 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; cycloalkyl groups such as cyclohexyl; 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. Alternatively, examples 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 unsubstituted or substituted 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 preferred, with a methyl group being particularly preferred. 1 may be the same group or different groups.

[0016] R 2R is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, or a hexyl group. 2 is preferably a hydrogen atom, a methyl group, or an ethyl group, and particularly preferably a hydrogen atom. 2 may be the same group or different groups.

[0017] In the above formula (1), the bifunctional diorganosiloxane unit (R 1 2SiO 2 / 2 The character a, which indicates the number of repetitions (or degree of polymerization) of the formula (1), is an integer of 1 to 10, preferably an integer of 1 to 5, and more preferably an integer of 1 to 3. If a is less than 1 (i.e., a=0), the reaction during synthesis of the raw material (i.e., the compound having a thiourea bond unit, which is the raw material for the organopolysiloxane represented by general formula (1)) will proceed with difficulty, and if it exceeds 10, the self-repairing properties of the cured product will decrease.

[0018] In the above formula (1), the difunctional diorganosiloxane unit (SiR 1 2O 2 / 2 The number b, which indicates the number of repetitions (or degree of polymerization) of the formula (a), is an integer of 1 to 200, preferably an integer of 5 to 100, and more preferably an integer of 10 to 50. If b is less than 1 (i.e., b=0), the condensation reaction during curing will be difficult to proceed, and if it exceeds 200, the self-repairing properties of the cured product will decrease.

[0019] In the above formula (1), x represents the number of repeating units (or degree of polymerization) having two thiourea structures in the main chain (thiourea bond unit), and the diorganopolysiloxane [(R 1 2SiO 2 / 2 ) band y, which indicates the number of repeating units (silicone units) consisting of the repeating unit [R, R, and R], is an integer of 1 to 50, preferably an integer of 2 to 40, more preferably an integer of 3 to 30, and even more preferably an integer of 4 to 20. If x is less than 1 (i.e., x = 0), the self-repairing properties of the cured product will not be exhibited, and if y is less than 1 (i.e., y = 0), the composition will not cure. If x or y each exceeds 50, the viscosity of the base polymer will become too high, making it difficult to handle.

[0020] In the above formula (1), the alkylene group -(CH2) exists at four positions in the unit (thiourea bond unit) having two thiourea structures in the main chain. n n, which indicates the number of repeating -, is independently an integer of 1 to 10, preferably an integer of 2 to 6, and more preferably an integer of 2 to 5. If n is less than 1 (i.e., n = 0), it becomes difficult to synthesize the raw material (i.e., a compound having a thiourea bond unit, which is a raw material for the organopolysiloxane represented by general formula (1)), and if n exceeds 10, the self-repairing properties of the cured product decrease.

[0021] The organopolysiloxane of component (A) may use either a single type alone, or two or more types in combination.

[0022] Examples of organopolysiloxanes represented by the above general formula (1) include those having the following structures: [ka] (In the formula, R 11 is a methyl group, an ethyl group, or a phenyl group, a1 is an integer of 1 to 5, b1 is an integer of 10 to 50, x1 is an integer of 4 to 20, y1 is an integer of 4 to 20, and n1 is an integer of 2 to 5. The repeating units shown in parentheses with x1 and y1 may be arranged randomly.

[0023] The organopolysiloxane of component (A) can be obtained, for example, by the following synthesis (preparation) method. That is, as shown in the following reaction formula [Ia], a silane coupling agent having a halogen group and a thiocyanate salt are reacted (aged) in an organic solvent such as dimethylformamide (DMF) at a molar ratio of 1:1 to 1:1.2 at 80 to 150°C, preferably 100 to 140°C, for 1 to 24 hours, preferably 4 to 12 hours, to synthesize a hydrolyzable silane containing a terminal thiocyanate group (-SCN).Then, the hydrolyzable silane containing a terminal thiocyanate group (-SCN) is extracted by distillation under reduced pressure while heating. [ka] (In the formula, R 7 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, and A 1 is a halogen atom, and A 2 is a sodium or potassium atom. 1 and n are the same as above.)

[0024] A 1 A is preferably a chlorine atom or a bromine atom, 2 A potassium atom is preferred as R. 7 Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group, and among these, a methyl group and an ethyl group are preferred.

[0025] Next, as shown in the following reaction formula [Ib], the obtained hydrolyzable silane containing a terminal thiocyanate group (-SCN) is heated in the presence of potassium iodide at 100 to 180°C, preferably 120 to 160°C, for 6 to 36 hours, preferably 10 to 24 hours, to synthesize a hydrolyzable silane containing a terminal thioisocyanate group (-NCS). [ka] (In the formula, R 1 , R 7 and n are the same as above.)

[0026] In this case, a commonly used solvent may be used, such as toluene, benzene, tetrahydrofuran, dimethylformamide, chloroform, or carbon tetrachloride. The amount of solvent used is 10 to 300, preferably 30 to 200, parts by mass per 100 parts by mass of the hydrolyzable silane containing a terminal thiocyanate group. In this case, the hydrolyzable silane containing a terminal thioisocyanate group (-NCS) is finally extracted by vacuum distillation under heating.

[0027] Furthermore, as shown in the following reaction formula [Ic], 2 to 2.2 moles of a hydrolyzable silane containing a terminal thioisocyanate group is added dropwise to 1 mole of a silicone compound having amino groups at both ends and mixed so that the exothermic temperature range is 25 to 80°C, and the mixture is allowed to react (age) at 0 to 120°C, preferably 20 to 90°C, for 1 to 12 hours, preferably 2 to 8 hours, to synthesize a hydrolyzable silane compound having two thiourea bonds in the molecule (i.e., a diorganopolysiloxane having two alkylene linker moieties with a thiourea structure on both sides of the main chain and having both molecular chain terminals blocked with hydrolyzable silyl groups). [ka] (In the formula, R 1 , R 7 , a and n are the same as above.)

[0028] Finally, the organopolysiloxane represented by general formula (1) can be synthesized by subjecting a condensation polymerization reaction between a silane compound having two thiourea bonds per molecule and hydrolyzable at both ends (i.e., a diorganopolysiloxane having two alkylene linkers with thiourea structures on both sides of the main chain and terminated at both molecular chain ends with hydrolyzable silyl groups) and a silicone compound having silanol groups at both ends (a diorganopolysiloxane terminated at both molecular chain ends with silanol groups) using a catalyst, and finally treating with water to terminate both molecular chain ends of the condensation polymerization product with silanol groups. This reaction is represented by the following reaction formula [Id]. [ka] (In the formula, R 1 , R 2 , R 7 , a, b, x, y, and n are the same as above.)

[0029] The ratio of the thiourea bond-containing hydrolyzable silane compound at both ends to the silicone compound having silanol groups at both ends, expressed as a molar ratio (x / y) of the thiourea bond-containing hydrolyzable silane compound at both ends to the silicone compound having silanol groups at both ends, is preferably 0.5 to 1.5, more preferably 0.7 to 1.3. If this molar ratio is less than 0.5, the self-repairing properties of the cured product (cured silicone rubber product) may decrease, while if it exceeds 1.5, the moisture curing properties may decrease.

[0030] Examples of catalysts used in the above polycondensation reaction include acids and bases, such as acetic acid, hydrochloric acid, sulfuric acid, nitric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, trimethylamine, triethylamine, tripropylamine, tributylamine, tetramethylguanidine, diazabicycloundecene, and diazabicyclononene, with tetramethylguanidine, diazabicycloundecene, and diazabicyclononene being preferred. The amount of catalyst added is 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the combined amount of the thiourea bond-containing, hydrolyzable silane compound at both ends and the silicone compound having silanol groups at both ends.

[0031] A commonly used solvent may be used in the above-mentioned condensation polymerization reaction, and examples thereof 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. The amount of the solvent used is not particularly limited, but is usually 5 to 500 parts by mass, preferably 10 to 400 parts by mass, and more preferably 20 to 300 parts by mass, relative to 100 parts by mass of the total amount of the thiourea bond-containing hydrolyzable silane compound at both ends and the silicone compound having silanol groups at both ends charged.

[0032] The reaction (condensation polymerization) conditions for a thiourea bond-containing, terminally hydrolyzable silane compound and a terminally silanol-containing silicone compound are typically 40 to 200°C, preferably 60 to 180°C, for approximately 3 to 30 hours. If the reaction temperature is too low, the reaction may not be completed, while if the reaction temperature is too high, the target product may be decomposed. If the reaction time is too short, the reaction may not be completed, while if the reaction time is too long, productivity is adversely affected.

[0033] Furthermore, the curability of the organopolysiloxane represented by general formula (1) can be improved by reacting a thiourea-bonded, terminally hydrolyzable silane compound with a silicone compound having terminal silanol groups, followed by the addition of water to hydrolyze the excess alkoxy groups and other hydrolyzable groups. The hydrolysis reaction (terminal silanol blocking) of the excess alkoxy groups and other hydrolyzable groups is preferably carried out at a temperature of 20 to 120°C, preferably 40 to 100°C, for approximately 1 to 15 hours. If the reaction temperature is too low, the reaction may not be completed, while if the reaction temperature is too high, the target product may be decomposed. If the reaction time is too short, the reaction may not be completed, while if the reaction time is too long, productivity is adversely affected.

[0034] The amount of water added in this case is not particularly limited, but is usually 0.1 to 100 parts by mass, preferably 0.5 to 80 parts by mass, and more preferably 1 to 50 parts by mass, relative to 100 parts by mass of the total amount of the thiourea bond-containing hydrolyzable silane compound at both ends and the silicone compound having silanol groups at both ends.

[0035] At the end of the reaction, the solvent is distilled off under heating and reduced pressure to obtain the organopolysiloxane represented by general formula (1).

[0036] [(B) Component] The component (B) used in the room-temperature-curable organopolysiloxane composition of the present invention acts as a crosslinking agent (curing agent) and is a hydrolyzable organosilane compound and / or a partial hydrolyzed condensate thereof, other than the components (C) and (D) described below, which has at least three hydrolyzable groups bonded to silicon atoms in each molecule. The organosilane compound is preferably a hydrolyzable organosilane compound and / or a partial hydrolyzed condensate thereof represented by the following general formula (3) (i.e., an organosiloxane oligomer having at least two, and preferably three or more, residual hydrolyzable groups in the molecule formed by partial hydrolyzed condensation of the organosilane compound): R 5 d SiR 6 4-d (3) (In the formula, R 5 is a monovalent hydrocarbon group, and R 6 is a hydrolyzable group. d is 0 or 1, preferably 1.

[0037] In general formula (3), hydrolyzable group R 6 Examples of the alkyl group include ketoxime groups, alkoxy groups, acyloxy groups, alkenyloxy groups, etc. Specific examples include ketoxime groups having 3 to 8 carbon atoms, such as a dimethyl ketoxime group, a methyl ethyl ketoxime group, and a methyl isobutyl ketoxime group; alkoxy groups having 1 to 4, particularly 1 or 2, carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group; acyloxy groups having 2 to 4 carbon atoms, such as an acetoxy group and a propionoxy group; and alkenyloxy groups having 2 to 5 carbon atoms, such as a vinyloxy group, an allyloxy group, a propenoxy group, an isopropenoxy group, and a cyclopenten-1-yloxy group.

[0038] In addition, the residual group R bonded to the silicon atom other than the hydrolyzable group 5is not particularly limited as long as it is a monovalent hydrocarbon group, but specific examples include monovalent hydrocarbon groups having 1 to 10 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, and butyl, alkenyl groups such as vinyl, and aryl groups such as phenyl. Of these, methyl, ethyl, vinyl, and phenyl groups are preferred.

[0039] Specific examples of such component (B) include ketoxime silanes such as tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutylketoxime)silane, and vinyltris(methylethylketoxime)silane; alkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, tetramethoxysilane, vinyltriethoxysilane, and tetraethoxysilane; acetoxysilanes such as methyltriacetoxysilane and vinyltriacetoxysilane; and alkenoxysilanes such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, phenyltriisopropenoxysilane, methyltri(cyclopenten-1-yloxy)silane, and vinyltri(cyclopenten-1-yloxy)silane; and partial hydrolysis condensates of these silanes. These may be used alone or in combination of two or more. Component (B) is clearly differentiated from component (D), which will be described later, in that it does not have a monovalent hydrocarbon group having a functional group containing a heteroatom such as nitrogen, oxygen, or sulfur in the molecule.

[0040] The blending amount of component (B) is 0.1 to 40 parts by mass, and preferably 5 to 30 parts by mass, per 100 parts by mass of component (A). If it is less than 0.1 part by mass, sufficient crosslinking is not achieved, making it difficult to obtain a composition with the desired rubber elasticity, while if it exceeds 40 parts by mass, the mechanical properties of the resulting cured product are likely to deteriorate.

[0041] [(C) component curing catalyst] The room-temperature-curable organopolysiloxane composition of the present invention contains a curing catalyst (component (C)). The curing catalyst (component (C)) can be a metallic or non-metallic condensation catalyst that has been conventionally used as a curing accelerator for room-temperature-curable organopolysiloxane compositions. Examples of suitable curing catalysts include organotin compounds (tin catalysts) such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, dimethyltin dimethoxide, and dimethyltin diacetate; organotitanium compounds (titanium catalysts) such as tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, dimethoxytitanium diacetylacetonate, and titanium diisopropoxybis(ethylacetoacetate); trititanium compounds (titanium catalysts) such as tetramethylsilane; and titanium tetraisopropyl silane. Examples of suitable organic bismuth catalysts include amine compounds such as ethylamine, hexylamine, and tetramethylguanidine; guanidyl group-containing hydrolyzable organosilane compounds such as γ-tetramethylguanidylpropyltrimethoxysilane; and salts thereof (organic strong base catalysts); and organic bismuth compounds such as bismuth tris(2-ethylhexanoate) and bismuth tris(neodecanoate); and mixtures thereof (organobismuth catalysts). At least one of these compounds, i.e., one compound, can be used alone, or two or more compounds can be used in combination.

[0042] The amount of component (C) blended is 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of component (A). If the amount of component (C) blended is less than the above lower limit of 0.01 part by mass, the catalytic effect will not be obtained, and if it exceeds the above upper limit of 10 parts by mass, the storage stability of the composition will be poor.

[0043] [Component (D): Silane coupling agent and / or partial hydrolysis condensate thereof] The room-temperature-curable organopolysiloxane composition of the present invention may optionally contain a silane coupling agent (component (D)) and / or a partial hydrolysis condensate thereof. Component (D) is a silane coupling agent represented by the following general formula (2) (i.e., a hydrolyzable organosilane compound or carbon functional silane having a functional group-containing monovalent hydrocarbon group) and / or a partial hydrolysis condensate thereof, and is a component for imparting good adhesive properties to the cured product of the room-temperature-curable organopolysiloxane composition of the present invention. R 3 R 4 c Six 3-c (2) (In the formula, R 3 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one functional group (excluding a guanidyl group) containing one or more heteroatoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom. 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is a hydrolyzable group. c is 0, 1, or 2.

[0044] In the above formula (2), R 3 is a monovalent hydrocarbon group (excluding a guanidyl group) having 1 to 20 carbon atoms and having at least one functional group containing one or more heteroatoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom (for example, an unsubstituted or substituted amino group, an unsubstituted or substituted imino group, an amido group, a ureido group, a mercapto group, an epoxy group, a (meth)acryloxy group, etc.), and specifically, a β-(2,3-epoxycyclohexyl)ethyl group, a β-(3,4-epoxycyclohexyl)ethyl group, a γ-glycidoxypropyl group, a γ-methacryloxypropyl group, a γ-glycid ... Examples of monovalent hydrocarbon groups include monovalent hydrocarbon groups having preferably 3 to 20 carbon atoms, more preferably 3 to 14 carbon atoms, containing at least one heteroatom selected from a nitrogen atom, a sulfur atom, and an oxygen atom, such as a hydroxypropyl group, a γ-acryloxypropyl group, an N-β-(aminoethyl)-γ-aminopropyl group [also known as an N-2-(aminoethyl)-3-aminopropyl group], a γ-aminopropyl group, an N-phenyl-γ-aminopropyl group, a γ-ureidopropyl group, a γ-mercaptopropyl group, and a γ-isocyanatopropyl group.3 As the alkyl group, a γ-glycidoxypropyl group, a γ-aminopropyl group, and an N-β-(aminoethyl)-γ-aminopropyl group are particularly preferred.

[0045] In addition, in the above formula (2), R 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, nonyl, and decyl; cycloalkyl groups such as cyclohexyl; 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. Alternatively, the hydrogen atoms of these hydrocarbon groups may be partially substituted with halogen atoms such as chlorine, fluorine, or bromine, such as trifluoropropyl. Among these, methyl, ethyl, propyl, and isopropyl groups are preferred. R 4 may be the same group or different groups.

[0046] In the above formula (2), examples of the hydrolyzable group X include ketoxime groups, alkoxy groups, alkoxyalkoxy groups, acyloxy groups, and alkenyloxy groups. Specific examples include ketoxime groups having 3 to 8 carbon atoms, such as dimethylketoxime groups, diethylketoxime groups, methylethylketoxime groups, and methylisobutylketoxime groups; alkoxy groups having 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms, such as methoxy groups, ethoxy groups, propoxy groups, isopropoxy groups, butoxy groups, isobutoxy groups, sec-butoxy groups, and tert-butoxy groups; alkoxyalkoxy groups having 2 to 4 carbon atoms, such as methoxymethoxy groups and methoxyethoxy groups; acyloxy groups having 2 to 4 carbon atoms, such as acetoxy groups and propionoxy groups; and alkenyloxy groups having 2 to 4 carbon atoms, such as vinyloxy groups, allyloxy groups, propenoxy groups, and isopropenoxy groups. X is preferably a methoxy group. The hydrolyzable groups X may be the same or different.

[0047] Specific examples of the silane coupling agent represented by formula (2) of component (D) include aminosilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-2-(aminoethylamino)propyltrimethoxysilane [also known as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane], epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, (meth)acrylic silanes such as γ-(meth)acryloxypropyltrimethoxysilane and γ-(meth)acryloxypropyltriethoxysilane, mercaptosilanes such as γ-mercaptopropyltrimethoxysilane, and isocyanate silanes such as γ-isocyanatepropyltrimethoxysilane.

[0048] The silane coupling agent and / or partial hydrolysis condensate thereof as component (D) may be used alone or in combination of two or more.

[0049] When component (D) is added, the amount added is preferably 0.01 to 5 parts by mass, and more preferably 0.1 to 4 parts by mass, per 100 parts by mass of component (A). If the amount is less than 0.01 part by mass, the cured product may not exhibit sufficient adhesive properties, while if the amount added exceeds 5 parts by mass, the rubber strength after curing may decrease, or the curability may decrease.

[0050] [Component (E): Inorganic filler] The room-temperature-curable organopolysiloxane composition of the present invention may optionally contain an inorganic filler (component (E)). The inorganic filler (component (E)) is a reinforcing or non-reinforcing filler that imparts rubber-like properties to the room-temperature-curable organopolysiloxane composition of the present invention.

[0051] Examples of the inorganic filler of component (E) include silica-based fillers such as dry silica (e.g., calcined silica, fumed silica), wet silica (e.g., precipitated silica, sol-gel silica), carbon black, talc, bentonite, surface-treated or untreated calcium carbonate, zinc carbonate, magnesium carbonate, surface-treated or untreated calcium oxide, zinc oxide, magnesium oxide, aluminum oxide, and aluminum hydroxide, among which calcium carbonate, fumed silica, precipitated silica, carbon black, and aluminum oxide are preferred, and calcium carbonate, fumed silica, precipitated silica, carbon black, and aluminum oxide whose surfaces have been hydrophobized are more preferred. In this case, it is preferable that these inorganic fillers have a low water content.

[0052] There are no particular limitations on the type, amount, treatment method, etc. of the surface treatment agent (hydrophobic treatment agent), but representative examples include organosilicon compounds such as chlorosilanes (dimethyldichlorosilane, etc.), alkoxysilanes, and organosilazanes, as well as fatty acids, paraffins, silane coupling agents, and titanium coupling agents. The inorganic filler of component (E) may be used alone or in combination of two or more different types.

[0053] When component (E) is blended, the blending amount is preferably 1 to 500 parts by mass, more preferably 5 to 500 parts by mass, even more preferably 10 to 300 parts by mass, and particularly preferably 10 to 250 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than 1 part by mass, sufficient rubber strength cannot be obtained, and the composition may not be suitable for the intended use. If the blending amount is more than 500 parts by mass, the ejection properties from the cartridge may deteriorate, storage stability may decrease, and the mechanical properties of the resulting rubber may also decrease.

[0054] [Other ingredients] In addition, the room-temperature-curable organopolysiloxane composition of the present invention may contain other commonly known additives in addition to the above-mentioned components, provided that the purpose of the present invention is not impaired. Examples of such additives include polyethers as thixotropy improvers, silicone oils (non-functional organopolysiloxanes) as plasticizers, and isoparaffins. If necessary, colorants such as pigments, dyes, and fluorescent whitening agents, physiologically active additives such as mildew inhibitors, antibacterial agents, and marine life repellents, surface modifiers such as phenylsilicone oils, fluorosilicone oils, and organic liquids incompatible with silicones as bleed oils, and solvents such as volatile oils and low-boiling-point isoparaffins can also be added.

[0055] The room-temperature-curable organopolysiloxane composition of the present invention contains, as described above, components (A), (B), and (C) as essential components, and preferably also components (D) and (E), and may further contain the other components (additives) described above. The composition can be obtained by uniformly mixing, in a dry atmosphere, the above components and the various additives in predetermined amounts.

[0056] The room-temperature-curable organopolysiloxane composition of the present invention, particularly a one-component room-temperature-curable organopolysiloxane composition, is readily cured at room temperature (23°C±15°C) by storing it in the absence of moisture, i.e., in a moisture-proof sealed container, and exposing it to moisture in the air at the time of use. That is, the room-temperature-curable organopolysiloxane composition of the present invention readily cures at room temperature (23°C±15°C) through a hydrolysis and condensation reaction when exposed to moisture in the air at the time of use, and has self-repairing properties in a room-temperature environment (i.e., when a silicone rubber cured product is damaged or broken, the damaged or broken parts can be bonded together and brought into contact over a predetermined area, and the cured product can be self-repaired under a predetermined load (5 to 50 kN / m 2 By applying a heat treatment (approximately 100°C), the cured product will recover its shape and / or physical properties over time at a predetermined recovery rate. Furthermore, the room-temperature-curable organopolysiloxane composition of the present invention exhibits good curability when used with a variety of existing catalysts, and the resulting cured product (silicone rubber) also has excellent adhesive properties.

[0057] Therefore, the room-temperature-curable organopolysiloxane composition of the present invention is useful as an adhesive, a sealant, a potting agent, a coating agent, etc. The room-temperature-curable organopolysiloxane composition of the present invention can be used as an adhesive, a sealant, a potting agent, or a coating agent according to a conventionally known method.

[0058] The room-temperature-curable organopolysiloxane composition of the present invention cures upon standing at room temperature, and the molding method and curing conditions for the cured product can be known and used according to the type of composition. Furthermore, the cured product (silicone rubber cured product) obtained by curing the room-temperature-curable organopolysiloxane composition of the present invention can be used to make various articles. Examples of such articles include automobile parts, automobile oil seals, electrical and electronic parts, building structures, and civil engineering structures. [Example]

[0059] The present invention will be explained in more detail below with reference to synthesis examples, working examples, and comparative examples, but the present invention is not limited to the following examples. Note that Me in the chemical formula represents a methyl group. The number-average molecular weight of the organopolysiloxane was determined by polystyrene conversion in gel permeation chromatography (GPC) analysis using toluene as the developing solvent.

[0060] [Synthesis Example 1] Potassium thiocyanate (855 g, 8.8 mol), 3-chloropropyldimethylethoxysilane (1446 g, 8.0 mol), and 1000 g of DMF (dimethylformamide) were charged into a 5 L separatory flask equipped with a Dimroth tube, stirrer, and thermometer, and aged for 6 hours at 120 °C. The mixture was then distilled at 120 °C and 4 torr to obtain starting material silane 1 (a hydrolyzable silane (Si(CH3)2(OC2H5)(CH2)3SCN) containing a terminal thiocyanate group (-SCN)) (yield: 1178 g, 72%). This reaction is represented by the following reaction equation [II]. [ka]

[0061] [Synthesis Example 2] The resulting starting material silane 1 (1050 g), 33 g of potassium iodide, and 500 g of DMF were mixed in a 3 L separatory flask equipped with a Dimroth tube, stirrer, and thermometer, and reacted at 160°C for 18 hours. The resulting mixture was then distilled at 110°C and 4 torr to obtain starting material silane 2 (a terminal thioisocyanate (-NCS)-containing hydrolyzable silane (Si(CH3)2(OC2H5)(CH2)3NCS)) (yield: 851 g, 81%). This reaction is represented by the following reaction formula [III]. [ka]

[0062] [Synthesis Example 3] A 0.5 L separatory flask equipped with a Dimroth tube, stirrer, and thermometer was charged with 105.4 g (0.40 mol) of bis(3-aminopropyl)-tetramethyldisiloxane, and 162.7 g (0.80 mol) of starting material silane 2 was added dropwise so that the exotherm ranged from 25 to 80°C. After the addition, the mixture was aged at 80°C for 3 hours to obtain starting material silane 3 (a tetramethyldisiloxane having two alkylene linkers with thiourea structures and capped at both molecular chain ends with hydrolyzable silyl groups) (yield: 267.5 g, 99%). This reaction is represented by the following reaction formula [IV]. [ka]

[0063] [Synthesis Example 4] A 2L separatory flask equipped with a Dimroth tube, stirrer, and thermometer was charged with 250g (0.38mol) of starting silane 3, 451.5g (0.38mol) of dimethylpolysiloxane with silanol groups at both ends and a degree of polymerization of 15, 10g of tetramethylguanidine, and 500g of toluene, and the mixture was reacted (condensation polymerization) at 110°C for 12 hours. Next, 50g of pure water was added, and the mixture was reacted at 90°C for 6 hours (terminal silanol blocking). The solvent was then distilled off at 120°C and 4 torr to obtain organopolysiloxane (base polymer 1) represented by formula (4) below (yield: 655g, yield: 94%, number average molecular weight: 13,000). This reaction is represented by the following reaction formula [V]. [ka] [ka]

[0064] [Example 1] To 100 parts by mass of (A) the base polymer 1, 5 parts by mass of (B) vinyltris(methylethylketoxime)silane was added and thoroughly mixed. Next, 0.1 parts by mass of (C) dioctyltin dilaurate was added and thoroughly mixed under reduced pressure to obtain composition 1.

[0065] [Example 2] (A) 100 parts by mass of the base polymer 1 was mixed with 10 parts by mass of (E) fumed silica whose surface was treated with dimethyldichlorosilane, and then 5 parts by mass of (B) vinyltris(methylethylketoxime)silane was added and thoroughly mixed. Next, 0.1 parts by mass of (C) dioctyltin dilaurate was added and thoroughly mixed under reduced pressure to obtain Composition 2.

[0066] [Comparative Example 1] (A') 100 parts by mass of dimethylpolysiloxane, both ends of which are terminated with silanol groups (hydroxydimethylsilyl groups) and have a viscosity of 20,000 mPa s at 23°C, was mixed thoroughly with 5 parts by mass of vinyltris(methylethylketoxime)silane (B). Next, 0.1 parts by mass of dioctyltin dilaurate (C) was added and mixed thoroughly under reduced pressure to obtain Composition 3.

[0067] Comparative Example 2 (A') 100 parts by mass of dimethylpolysiloxane with a viscosity of 20,000 mPa s at 23°C and both molecular chain terminals blocked with silanol groups (hydroxydimethylsilyl groups) was mixed with (E) 10 parts by mass of fumed silica with a surface treated with dimethyldichlorosilane, and then 5 parts by mass of (B) vinyltris(methylethylketoxime)silane was added and mixed thoroughly. Next, 0.1 parts by mass of (C) dioctyltin dilaurate was added and mixed thoroughly under reduced pressure to obtain Composition 4.

[0068] [Test method] The following evaluations were carried out for each of the compositions (room-temperature-curable organopolysiloxane compositions) prepared in Examples 1 and 2 and Comparative Examples 1 and 2. The evaluation results are shown in Table 1.

[0069] Rubber properties Each composition prepared in the above Examples and Comparative Examples was poured into a 2 mm mold and cured at 23°C and 50% RH for 7 days to obtain a 2 mm thick rubber sheet. The rubber physical properties (type A durometer hardness, tensile strength, and elongation at break) were measured in accordance with JIS K 6249.

[0070] self-healing The fracture surfaces of the test pieces broken in the rubber physical property tests were overlapped to an area of ​​5 mm x 5 mm, fixed with a 50 g weight, and left to stand at 23°C for 12 hours. The rubber physical property tests (tensile strength, elongation at break) were then measured again to confirm the extent to which the physical properties had been restored. The restoration rate (= (value at re-measurement) / (initial value) x 100 (%)) was also calculated and evaluated.

[0071] [Table 1]

[0072] The above results show that even if the cured product of the room-temperature-curable organopolysiloxane composition of the Example breaks, it can self-repair by bonding the fractured surfaces together at room temperature (by applying a load to a fixed area and bringing them into contact), and it has a recovery rate of 60% or more for both tensile strength and elongation at break. On the other hand, the cured product of the room-temperature-curable organopolysiloxane composition of the Comparative Example, which is a conventional silicone composition, did not recover (self-repair) at all even when the fractured surfaces were bonded together, and it was not possible to measure again. It has been found that the room-temperature-curable organopolysiloxane composition of the present invention can provide a cured product that has excellent self-repairing properties while having rubber physical properties equivalent to those of cured products from conventional room-temperature-curable organopolysiloxane compositions.

Claims

1. (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1): 【Chemistry 1】 (In the formula, R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 may be the same or different groups, R 2 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and each R 2 may be the same or different groups. a is an integer from 1 to 10, and b is an integer from 1 to 200. x and y are each an integer from 1 to 50, and n is independently an integer from 1 to 10. In addition, the repeating units shown in parentheses with x and y may be arranged randomly. (B) a hydrolyzable organosilane compound having three or more silicon-bonded hydrolyzable groups in the molecule and / or a partial hydrolysis condensate thereof: 0.1 to 40 parts by mass, and (C) Curing catalyst: 0.01 to 10 parts by mass A room temperature curable organopolysiloxane composition comprising:

2. The room-temperature-curable organopolysiloxane composition according to claim 1, further comprising, as component (D), 0.01 to 5 parts by mass of a silane coupling agent represented by the following general formula (2) and / or a partial hydrolysis condensate thereof, per 100 parts by mass of component (A): R 3 R 4 c SiX 3-c (2) (In the formula, R 3 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one functional group (excluding guanidyl groups) containing one or more heteroatoms selected from a nitrogen atom, a sulfur atom, and an oxygen atom. 4 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is a hydrolyzable group. c is 0, 1, or 2.

3. 2. The room temperature curable organopolysiloxane composition according to claim 1, further comprising at least one inorganic filler as component (E).

4. A cured product obtained by curing the room temperature curable organopolysiloxane composition according to any one of claims 1 to 3.

5. An article comprising the cured product according to claim 4.

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