Room-temperature-curable organopolysiloxane composition for automotive long-life coolant sealing, automotive long-life coolant sealant, and automotive long-life coolant sealing material

Abstract

To provide a room-temperature-curable organopolysiloxane composition for automotive long-life coolant sealing that exhibits superior curability to yield a cured product with superior resistances to LLC and heat as well as superior adhesion, while ensuring reduced VOC content, where the composition is suitable as a material for FIPG, a sealant composed of the composition, and a sealing material made by curing the sealant.SOLUTION: A composition contains a compound represented by formula (3) in a specific amount. (R4 and R6 each represent an unsubstituted or substituted C1-12 monovalent hydrocarbon group excluding aliphatic unsaturated bonds, R5 represents a hydrogen atom or a C2-12 aliphatic unsaturated monovalent hydrocarbon group, A represents a C2-8 bivalent hydrocarbon group, k represents 0-2, m represents 3-6, k+m represents 3-8, and n represents 0-100.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a room-temperature curable organopolysiloxane composition, in particular a room-temperature curable organopolysiloxane composition for automobile LLC seals, which is suitably used as an automobile long-life coolant (hereinafter also referred to as LLC) sealant (automobile long-life coolant sealant).The present invention particularly relates to the room-temperature curable organopolysiloxane composition for automobile LLC seals, which has good curability and gives a cured product (silicone rubber) that is excellent in LLC resistance and heat resistance as well as good adhesiveness, an automobile long-life coolant sealant comprising the composition, and an automobile long-life coolant sealant (automobile long-life coolant sealant) obtained by curing the sealant. [Background technology]

[0002] Conventionally, gaskets and packing materials made of cork, organic rubber, asbestos, etc. have been used as sealing materials around the LLC of automobiles. However, these conventional gaskets and packing materials have the disadvantages of complicated inventory management and work processes, and furthermore, their sealing performance is unreliable. To eliminate these drawbacks, room temperature curable organopolysiloxane compositions formed by the Formed In Place Gasket (FIPG) method (liquid gaskets) are used as LLC sealing materials.

[0003] In recent years, various additives have been added to LLC to improve the performance of coolants. FIPG is also required to have higher LLC resistance. LLC is basically used by mixing it with water. Therefore, automotive LLC sealants must be able to withstand high temperature conditions in the presence of highly aggressive chemicals, such as a mixture of LLC and water.

[0004] In JP 2002-226708 A (Patent Document 1), it is reported that LLC resistance is improved by adding a hydrophobized filler to a two-liquid mixture type FIPG. However, since a mixing process is added to a two-liquid mixture type FIPG, there is a drawback in that the management in the production process becomes complicated. In addition, in JP 2016-199687 A (Patent Document 2), it is reported that LLC resistance is improved by adding an adhesion imparting agent with high water resistance. However, in recent years, there has been a demand for improvement of LLC resistance under conditions stricter than 100°C, 168 hours of immersion.

[0005] Furthermore, JP 2018-184520 A (Patent Document 3) discloses that the addition of an organopolysiloxane resin with a three-dimensional network structure to a composition can improve LLC resistance. However, when a composition containing an organopolysiloxane resin with a three-dimensional network structure is added, the remaining silanol groups undergo a condensation reaction, and a decrease in the elongation of the rubber is unavoidable when the composition is exposed to a high-temperature environment.

[0006] Furthermore, in view of the recent heightened interest in environmental protection and the health management of on-site workers, materials containing volatile organic compounds (VOCs) in the composition are undesirable. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-226708 A [Patent Document 2] JP 2016-199687 A [Patent Document 3] JP 2018-184520 A 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 an object to provide a room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals which has good curability, excellent LLC resistance and heat resistance, gives a cured product (silicone rubber) having good adhesion, and further has a reduced VOC content, making it suitable as a material for FIPG; an automotive long-life coolant sealant comprising the composition; and an automotive long-life coolant sealant (automotive long-life coolant sealant) obtained by curing the sealant. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to achieve the above object, and have found that an automobile long-life coolant sealant made of a room-temperature curable organopolysiloxane composition for automobile long-life coolant seals, which contains a specific amount of a cyclic organopolysiloxane compound having a silanol group-containing organopolysiloxane in its side chain, significantly improves the LLC resistance and curability of an automobile long-life coolant sealant (automobile long-life coolant sealant) obtained by curing the sealant. In addition, the inventors have found that the composition has sufficient LLC resistance and significantly improves heat resistance (elongation reduction when exposed to high temperatures) even without using an organopolysiloxane resin with a three-dimensional network structure (so-called silicone resin), and have thus completed the present invention.

[0010] Accordingly, the present invention provides the following room-temperature curable organopolysiloxane composition for automobile long-life coolant seals, automobile long-life coolant sealant, and automobile long-life coolant sealant (automobile long-life coolant sealant). 1. (A) 100 parts by mass of an organopolysiloxane having a viscosity of 2,000 mPa s or more at 23°C and represented by the following general formula (1): HO-(SiR 1 2 O) a -H (1) (In formula (1), R 1is an unsubstituted or substituted 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 100 or more. (B) inorganic filler: 1 to 500 parts by mass, (C) a hydrolyzable organosilane compound having at least three hydrolyzable groups bonded to silicon atoms in one molecule other than the components (A) and (D) and / or a partial hydrolysis condensate thereof: 0.1 to 50 parts by mass, (D) a silane coupling agent represented by the following general formula (2) and / or a partial hydrolysis condensate thereof other than the component (A): 0.01 to 10 parts by mass, R 2 R 3 b Six 1 3-b (2) (In formula (2), R 2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one atom selected from a nitrogen atom, a sulfur atom, and an oxygen atom; R 3 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and X 1 is a hydrolyzable group; b is 0, 1 or 2; (E) curing catalyst: 0.01 to 20 parts by mass, and (F) a cyclic organopolysiloxane compound represented by the following general formula (3): 0.1 to 10 parts by mass [ka] (In the formula, R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, R 5 are independently a hydrogen atom or an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R 6 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, A is independently a divalent hydrocarbon group having 2 to 8 carbon atoms, k is an integer of 0 to 2, m is an integer of 3 to 6, k+m is an integer of 3 to 8, and n is an integer of 0 to 100. A room-temperature curable organopolysiloxane composition for use in long-life automotive coolant seals, comprising: 2. A room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals as described in 1, in which the inorganic filler of component (B) is at least one selected from calcium carbonate, fumed silica, precipitated silica and aluminum oxide, which has been hydrophobized with a surface treatment agent, or carbon black. 3. A room-temperature-curable organopolysiloxane composition for use in long-life automotive coolant seals as described in 1 or 2, in which the residual VOC content in the composition is 5,000 ppm or less. 4. A room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals according to any one of 1 to 3, which gives a cured product in which, compared to the initial state, the rate of change in tensile strength and elongation at break after an LLC resistance test in which the product is immersed in an automotive long-life coolant at 120°C for 240 hours is from -50% to 100%, and the rate of change in tensile strength and elongation at break after a heat resistance test at 120°C for 1,000 hours is from -50% to 50%. 5. A long-life automotive coolant sealant comprising the room-temperature-curable organopolysiloxane composition for use in long-life automotive coolant seals according to any one of 1 to 4. 6. A long-life coolant sealant for automobiles obtained by curing the long-life coolant sealant for automobiles described in 5. Effect of the Invention

[0011] The room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals of the present invention has particularly good curability, and gives a cured product (silicone rubber) that has excellent LLC resistance and heat resistance as well as good adhesion, and has a reduced VOC content, making it suitable as an automotive long-life coolant sealant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will now be described in further detail. [Room-temperature curable organopolysiloxane composition for long-life automotive coolant seals] The room temperature curable organopolysiloxane composition for long-life automotive coolant seals of the present invention contains the following components (A) to (F), where room temperature means 23°C±15°C, and preferably 20 to 25°C.

[0013] [Component (A): Organopolysiloxane] The organopolysiloxane of the component (A) is represented by the following general formula (1). HO-(SiR 1 2 O) a -H (1) (In formula (1), 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. a is an integer of 100 or more.

[0014] As shown in formula (1), component (A) is a linear diorganopolysiloxane whose main chain is composed of repeating diorganosiloxane units and whose molecular chain is terminated at both ends with hydroxyl groups (silanol groups) bonded to silicon atoms and has a viscosity of 2,000 mPa s or greater at 23°C. This component functions as the main agent (base polymer) of the room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals of the present invention.

[0015] In the general formula (1), R 1is 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, hexyl, octyl, and 2-ethylhexyl 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 fluorine, chlorine, 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, specifically, an alkyl group such as a methyl group, or an aryl group such as a phenyl group, and a methyl group is particularly preferred. 1 may be the same group or different groups.

[0016] In the general formula (1), the difunctional diorganosiloxane unit ((SiR 1 2 O 2 / 2 a, which indicates the number of repetitions (or degree of polymerization) of the formula (1), may be an integer of 100 or more, preferably an integer of 100 to 2,000, more preferably an integer of 150 to 1,000, and particularly preferably an integer of 200 to 800.

[0017] The viscosity of the organopolysiloxane of component (A) at 23°C is 2,000 mPa·s or more, preferably in the range of 2,000 to 500,000 mPa·s, more preferably 3,000 to 500,000 mPa·s, and particularly preferably 5,000 to 100,000 mPa·s. In the present invention, the viscosity is a value measured using a rotational viscometer (for example, BL type, BH type, BS type, cone-plate type, etc.).

[0018] In the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as a 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. The organopolysiloxane of the component (A) may be used alone or in combination of two or more different types.

[0019] [Component (B): Inorganic filler] Next, the inorganic filler which is component (B) is a reinforcing or non-reinforcing filler that imparts excellent rubber physical properties to the room temperature curable organopolysiloxane composition for long-life automotive coolant seals of the present invention.

[0020] Examples of the inorganic filler of component (B) include inorganic fillers that have been surface-treated (hydrophobized) or have not been surface-treated. That is, examples of the inorganic filler include silica-based fillers such as dry silica such as calcined silica and fumed silica (fumed silica), wet silica such as precipitated silica and sol-gel silica; carbon black, talc, bentonite, calcium carbonate, zinc carbonate, magnesium carbonate, calcium oxide, zinc oxide, magnesium oxide, aluminum oxide, and aluminum hydroxide. Among these, calcium carbonate, fumed silica, precipitated silica, carbon black, and aluminum oxide are preferred. In addition, the inorganic filler of component (B) is preferably a hydrophobic inorganic filler, and more preferably calcium carbonate, fumed silica, precipitated silica, and aluminum oxide, the surfaces of which have been hydrophobized, and hydrophobic carbon black, the surfaces of which have not been surface-treated. In this case, it is preferred that these inorganic fillers have a low moisture content. There are no particular limitations on the type, amount, treatment method, etc. of the surface treatment agent, but typically, known treatment methods using treatment agents such as organosilicon compounds such as chlorosilanes, alkoxysilanes, and organosilazanes, fatty acids, paraffins, silane coupling agents, and titanium coupling agents can be used.

[0021] The inorganic filler of component (B) may be used alone or in combination of two or more kinds. The amount of component (B) is in the range of 1 to 500 parts by mass, preferably 20 to 300 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is less than 1 part by mass, the resulting cured product will not have sufficient rubber strength, and will be unsuitable for use as an automobile LLC seal. On the other hand, if the amount of component (B) is more than 500 parts by mass, the ejection from the cartridge will be impaired, storage stability will be reduced, and the mechanical properties of the resulting rubber will also be reduced.

[0022] [Component (C): Hydrolyzable organosilane compound and / or its partial hydrolysis condensate] Component (C) acts as a crosslinking agent (curing agent) and is a hydrolyzable organosilane compound and / or a partial hydrolyzed condensate thereof other than component (A) and components (D) and (F) described below, which has at least three (particularly three or four) hydrolyzable groups bonded to silicon atoms in one molecule. As the organosilane compound, a hydrolyzable organosilane compound and / or a partial hydrolyzed condensate thereof represented by the following general formula (4) (i.e., an organosiloxane oligomer having at least two, preferably three or more, residual hydrolyzable groups in the molecule produced by partial hydrolysis and condensation of the organosilane compound) is preferred. R 7 c Six 2 4-c (4) (In the formula, R 7 is an unsubstituted or halogen-substituted monovalent hydrocarbon radical, and X 2 is a hydrolyzable group. c is 0 or 1, preferably 1.

[0023] In the general formula (4), X which is a hydrolyzable group 2Examples of X include ketoxime groups, alkoxy groups, acyloxy groups, and alkenyloxy groups. Specific examples include ketoxime groups having 3 to 8 carbon atoms, such as dimethyl ketoxime groups, methyl ethyl ketoxime groups, and methyl isobutyl ketoxime groups; alkoxy groups having 1 to 4, particularly 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; acyloxy groups having 2 to 4 carbon atoms, such as acetoxy groups and propionoxy groups; and alkenyloxy groups having 2 to 5 carbon atoms, such as vinyloxy groups, allyloxy groups, propenoxy groups, isopropenoxy groups, and cyclopent-1-en-1-yloxy groups. 2 may be the same group or different groups.

[0024] In addition, in the general formula (4), the remaining group R bonded to the silicon atom other than the hydrolyzable group 7 is not particularly limited as long as it is an unsubstituted or halogen-substituted monovalent hydrocarbon group, specific examples include unsubstituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, and butyl, alkenyl groups such as vinyl, and aryl groups such as phenyl, as well as halogen-substituted monovalent hydrocarbon groups such as chloromethyl and trifluoropropyl, in which some of the hydrogen atoms bonded to the carbon atoms of the unsubstituted monovalent hydrocarbon group are substituted with halogen atoms such as fluorine, chlorine, and bromine. Among these, unsubstituted monovalent hydrocarbon groups are preferred, and methyl, ethyl, vinyl, and phenyl groups are more preferred.

[0025] Specific examples of such component (C) 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, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane; Examples of the silanes include acyloxysilanes such as acetoxysilanes, such as ethyltriacetoxysilane, vinyltriacetoxysilane, and phenyltriacetoxysilane; isopropenoxysilanes, such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, and phenyltriisopropenoxysilane; alkenyloxysilanes such as silyl enol ethers, such as methyltris[(cyclopent-1-en-1-yl)oxy]silane, vinyltris[(cyclopent-1-en-1-yl)oxy]silane, and phenyltris[(cyclopent-1-en-1-yl)oxy]silane; and partial hydrolysis condensates of these silanes. These may be used alone or in combination of two or more.

[0026] In addition, component (C) does not contain (SiR 1 2 O 2 / 2 ) a (R 1 (a) is a repeating structure of linear diorganosiloxane units represented by the formula (a) (where a is the same as above) and does not have silanol groups, and is therefore clearly differentiated from component (A) described above. It is also clearly differentiated from component (D) described below 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. It is also clearly differentiated from component (F) described below in that it does not have a cyclic structure and does not have silanol groups.

[0027] The amount of component (C) used is within the range of 0.1 to 50 parts by mass, and preferably within the range of 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 obtained, and it is difficult to obtain a composition with the desired rubber elasticity, while if it exceeds 50 parts by mass, the mechanical properties of the obtained cured product are likely to deteriorate.

[0028] [Component (D): Silane coupling agent and / or partial hydrolysis condensate thereof] Next, 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 an essential component for imparting good adhesion to the room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals of the present invention. R 2 R 3 b Six 1 3-b (2) (In formula (2), R 2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one atom selected from a nitrogen atom, a sulfur atom, and an oxygen atom; R 3 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and X 1 is a hydrolyzable group. b is 0, 1 or 2, preferably 0.

[0029] In the general formula (2), R 2is a monovalent hydrocarbon group having 1 to 20 carbon atoms and containing at least one atom selected from nitrogen atoms, sulfur atoms, and oxygen atoms, excluding guanidyl groups (for example, unsubstituted or substituted amino groups, unsubstituted or substituted imino groups, amido groups, ureido groups, mercapto groups, epoxy groups, (meth)acryloxy groups, etc.). Specific examples include monovalent hydrocarbon groups having preferably 3 to 20 carbon atoms, more preferably 8 to 14 carbon atoms, and containing at least one atom selected from nitrogen atoms, sulfur atoms, and oxygen atoms, such as a β-(2,3-epoxycyclohexyl)ethyl group, a β-(3,4-epoxycyclohexyl)ethyl group, a γ-glycidoxypropyl group, a γ-(meth)acryloxypropyl group, a γ-acryloxypropyl group, an N-β(aminoethyl)-γ-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.

[0030] In addition, in the general formula (2), R 3 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and 2-ethylhexyl; 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 fluorine, chlorine, and bromine, such as trifluoropropyl, and the like, with methyl, ethyl, propyl, and isopropyl being preferred. 3 may be the same group or different groups.

[0031] In the general formula (2), X which is a hydrolyzable group 1Examples of 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 1 may be the same group or different groups.

[0032] Specific examples of the silane coupling agent of the component (D) include aminosilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-2-(aminoethylamino)propyltrimethoxysilane, etc.; epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; (meth)acrylic silanes such as γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, etc.; mercaptosilanes such as γ-mercaptopropyltrimethoxysilane, etc.; and isocyanate silanes such as γ-isocyanatepropyltrimethoxysilane, etc., with γ-aminopropyltrimethoxysilane being preferred. The silane coupling agent and / or partial hydrolysis condensate thereof as the component (D) may be used alone or in combination of two or more kinds.

[0033] Component (D) differs from components (A) and (C) described above, and component (F) described below, in that component (D) has a monovalent hydrocarbon group having a functional group containing a heteroatom, such as nitrogen, oxygen, or sulfur, in the molecule.

[0034] The amount of component (D) is 0.01 to 10 parts by mass, and preferably 0.1 to 8 parts by mass, per 100 parts by mass of component (A). If it is less than 0.01 part by mass, the cured product will not exhibit sufficient adhesive performance, and if it is blended in excess of 10 parts by mass, the curability will decrease and the rubber strength after curing will decrease.

[0035] [(E) component curing catalyst] The component (E) is a curing catalyst. As the curing catalyst, a condensation catalyst that has been generally used as a curing accelerator for compositions can be used. For example, organic tin compounds such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, dimethyltin dimethoxide, and dimethyltin diacetate; organic titanium compounds such as tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, and dimethoxytitanium diacetylacetonate; amine compounds such as hexylamine and guanidyl group-containing alkoxysilane compounds such as tetramethylguanidylpropyltrimethoxysilane, and salts thereof can be mentioned, and one of these can be used alone or two or more can be used in combination.

[0036] The amount of component (E) is 0.01 to 20 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass, per 100 parts by mass of component (A). If the amount of component (E) is less than the lower limit of 0.01 parts by mass, the catalytic effect is not obtained. If the amount of component (E) is more than the upper limit of 20 parts by mass, the adhesion of the room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals is reduced, and the storage stability is deteriorated.

[0037] [Component (F): Cyclic organopolysiloxane compound] Component (F) is a cyclic organopolysiloxane compound represented by the following general formula (3), which has a linear organopolysiloxane structure containing 3 to 6 terminal silanol groups in the molecule on its side chain via a divalent hydrocarbon group. When the room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals of the present invention is used as an automotive long-life coolant sealant, this component contributes to improving the LLC resistance and curing properties of the automotive long-life coolant sealant obtained by curing the sealant. [ka] (In the formula, R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, R 5 are independently a hydrogen atom or an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R 6 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, A is independently a divalent hydrocarbon group having 2 to 8 carbon atoms, k is an integer of 0 to 2, m is an integer of 3 to 6, k+m is an integer of 3 to 8, and n is an integer of 0 to 100.

[0038] In the general formula (3), R 4 Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, as represented by the formula (1), include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and α- and β-naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, chlorine, and bromine, or with cyano groups, for example, 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl. Among these, R 4R is preferably a lower alkyl group such as a methyl group, an ethyl group, an isopropyl group, or a butyl group, or an aryl group such as a phenyl group, and particularly preferably a methyl group or a phenyl group. 4 may be the same group or different groups.

[0039] In the general formula (3), R 5 Among the hydrogen atoms or aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms represented by the formula (I), examples of the aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms include alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, pentenyl group, hexenyl group, and cyclohexenyl group; and alkynyl groups such as ethynyl group (acetylenyl group) and ethynylmethyl group. 5 R is preferably a hydrogen atom or an alkenyl group such as a vinyl group or an allyl group, and more preferably a hydrogen atom or a vinyl group. 5 may be the same group or different groups.

[0040] In the general formula (3), R 6 Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, as represented by the formula (1), include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and α- and β-naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, chlorine, and bromine, or with cyano groups, for example, 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl. Among these, R 6 R is preferably a lower alkyl group such as a methyl group, an ethyl group, an isopropyl group, or a butyl group, or an aryl group such as a phenyl group, and particularly preferably a methyl group or a phenyl group. 6may be the same group or different groups.

[0041] In the general formula (3), A is a divalent hydrocarbon group such as an alkylene group or an alkenylene group having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. The divalent hydrocarbon group is, for example, -(CH 2 ) p - (p is an integer of 2 to 8, preferably an integer of 2 to 4) and other alkylene groups are preferred. Among these, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 A is preferably the same or different.

[0042] In formula (3), k is an integer of 0 to 2, and preferably 0 or 1. In the general formula (3), m is an integer of 3 to 6, and preferably 4 or 5. In the general formula (3), k+m is an integer of 3-8, and preferably an integer of 4-6.

[0043] In formula (3), n is an integer of 0 to 100, preferably an integer of 0 to 20, more preferably an integer of 0 to 10, and further preferably an integer of 0 to 4.

[0044] <Method for producing cyclic organopolysiloxane compound> The cyclic organopolysiloxane compound represented by the general formula (3) can be produced by a method including the following steps [I] or [II]. [I] The following general formula (5) [ka] (In the formula, R 6 , n is the same as above.) and an organohydrogensilane or organohydrogenpolysiloxane represented by the following general formula (6): [ka] (In the formula, R 4 , k, m, k+m are the same as above, and R 5’ is an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms. in the presence of a platinum compound-containing catalyst. [II] The following general formula (7) [ka] (In the formula, R 6 , n is the same as above, and R 5’ is an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms. and an organosilane or organopolysiloxane represented by the following general formula (8): [ka] (In the formula, R 4 , k, m, and k+m are the same as above.) in the presence of a platinum compound-containing catalyst.

[0045] Specifically, the present invention relates to an organohydrogensilane represented by the above formula (5) having a silanol group (a hydroxyl group bonded to a silicon atom) and a silicon-bonded hydrogen atom (a hydrosilyl group represented by SiH) in the molecule (when n=0 in formula (5)) or an organohydrogenpolysiloxane having a silanol group at one end of the molecular chain and a silicon-bonded hydrogen atom at the other end of the molecular chain (when n=1 to 100 in formula (5)), and an aliphatic unsaturated monovalent hydrocarbon group (R 5’ ) in the presence of a platinum compound-containing catalyst, or a cyclic organopolysiloxane having a silanol group and an aliphatic unsaturated monovalent hydrocarbon group (R 5’) (where n = 0 in formula (7)) or an organosilane having an aliphatic unsaturated monovalent hydrocarbon group (R 5’ ) and a silanol group at the other end of the molecular chain (where n = 1 to 100 in formula (7)) is subjected to a hydrosilylation addition reaction with a cyclic organohydrogenpolysiloxane having a silicon-bonded hydrogen atom represented by formula (8) above, in the presence of a platinum compound-containing catalyst, to obtain an aliphatic unsaturated monovalent hydrocarbon group (R 5’ ) to form a carbon-silicon bond (i.e., the silicon-bonded hydrogen atom (SiH group) in the above formula (5) and the aliphatic unsaturated monovalent hydrocarbon group (R 5’ ), or an addition reaction between a silicon-bonded hydrogen atom (SiH group) in the above formula (8) and an aliphatic unsaturated monovalent hydrocarbon group (R 5’ ) to form a divalent hydrocarbon group such as an alkylene group and / or an alkenylene group represented by A in the above formula (3), thereby producing a cyclic organopolysiloxane compound represented by the above formula (3).

[0046] In the general formulas (6) and (7), R 5’ As the aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms represented by the formula (3), R 5 Among these, the same groups as those exemplified as the aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms can be mentioned. 5’ As the alkyl group, a vinyl group, an alkenyl group such as an allyl group, etc. are preferred, and a vinyl group is particularly preferred.

[0047] Specific examples of the organohydrogensilane or organohydrogenpolysiloxane represented by the above formula (5) include those shown below. [ka] (In the formula, n is the same as above.)

[0048] Specific examples of the cyclic organopolysiloxane represented by the above formula (6) include those shown below. [ka]

[0049] Specific examples of the organosilane or organopolysiloxane represented by the above formula (7) include those shown below. [ka] (In the formula, n is the same as above.)

[0050] Specific examples of the cyclic organohydrogenpolysiloxane represented by the above formula (8) include those shown below. [ka]

[0051] Regarding the reaction ratio of the organohydrogensilane or organohydrogenpolysiloxane represented by formula (5) and the cyclic organopolysiloxane represented by formula (6), in consideration of suppressing by-products during the hydrosilylation addition reaction and improving the storage stability and properties of the resulting cyclic organopolysiloxane compound, the ratio of 0.5 to 1.5 mol of aliphatic unsaturated monovalent hydrocarbon groups such as alkenyl groups and alkynyl groups in the cyclic organopolysiloxane represented by formula (6) per 1 mol of hydrosilyl groups (SiH groups) in the organohydrogensilane or organohydrogenpolysiloxane represented by formula (5) is preferably 0.7 to 1.4 mol.

[0052] In addition, the reaction ratio of the organosilane or organopolysiloxane represented by formula (7) and the cyclic organohydrogenpolysiloxane represented by formula (8) is preferably 0.5 to 1.5 mol, and more preferably 0.7 to 1.4 mol, of aliphatic unsaturated monovalent hydrocarbon groups such as alkenyl groups and alkynyl groups in the organosilane or organopolysiloxane represented by formula (7) per 1 mol of hydrosilyl groups (SiH groups) in the cyclic organohydrogenpolysiloxane represented by formula (8), in order to suppress by-products during the hydrosilylation addition reaction and to improve the storage stability and properties of the resulting cyclic organopolysiloxane compound.

[0053] The platinum compound-containing catalyst used in the hydrosilylation addition reaction is not particularly limited, and specific examples thereof include chloroplatinic acid, an alcohol solution of chloroplatinic acid, a toluene or xylene solution of a platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, tetrakistriphenylphosphine platinum, dichlorobistriphenylphosphine platinum, dichlorobisacetonitrile platinum, dichlorobisbenzonitrile platinum, dichlorocyclooctadiene platinum, platinum-carbon, platinum-alumina, platinum-silica, and other supported catalysts. Among these, a toluene or xylene solution of a platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex is preferred from the viewpoint of the position selectivity of the hydrosilylation addition reaction.

[0054] The amount of the platinum compound-containing catalyst used is not particularly limited, but from the viewpoint of reactivity and productivity, it is preferable that the amount of platinum atoms contained is 1×10 per mol of the organosilane compound or organopolysiloxane compound having an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or an alkynyl group represented by the above formula (6) or (7). -7 ~1×10 -2 The preferred amount is 1×10 -7 ~1×10 -3 A molar amount is more preferred.

[0055] A cocatalyst may be used to improve the reactivity of the hydrosilylation addition reaction. Any cocatalyst generally used in hydrosilylation addition reactions can be used as the cocatalyst, but in the present invention, ammonium salts of inorganic acids, acid amide compounds, and carboxylic acids are preferred.

[0056] Specific examples of ammonium salts of inorganic acids include ammonium chloride, ammonium sulfate, ammonium amidosulfate, ammonium nitrate, monoammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium hypophosphite, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfide, ammonium borate, ammonium fluoroborate, etc. Among these, ammonium carbonate and ammonium hydrogen carbonate are preferred.

[0057] Specific examples of acid amide compounds include formamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, acrylamide, malonamide, succinamide, maleamide, fumaramide, benzamide, phthalamide, palmitic acid amide, stearic acid amide, and the like. Among these, formamide and stearic acid amide are preferred, and formamide is more preferred.

[0058] Specific examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, methoxyacetic acid, pentanoic acid, caproic acid, heptanoic acid, octanoic acid, lactic acid, glycolic acid, trifluoroacetic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, and oxalic acid. Among these, formic acid, acetic acid, lactic acid, maleic acid, fumaric acid, succinic acid, and trifluoroacetic acid are preferred, and acetic acid and trifluoroacetic acid are more preferred.

[0059] The amount of the co-catalyst used is not particularly limited, but from the viewpoints of the reactivity and site selectivity of the hydrosilylation addition reaction, cost, etc., it is preferable to use an amount of the co-catalyst of 1×10 per mol of the organosilane compound or organopolysiloxane compound having an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or an alkynyl group represented by the above formula (6) or (7). -5 ~1×10-1 mol is preferred, 1×10 -4 ~5×10 -1 mol is more preferred.

[0060] The hydrosilylation addition reaction proceeds without a solvent, but a solvent can also be used. Specific examples of solvents that can be used include hydrocarbon solvents such as pentane, hexane, cyclohexane, heptane, isooctane, benzene, toluene, and xylene; ether solvents such as diethyl ether, tetrahydrofuran, and dioxane; ester solvents such as ethyl acetate and butyl acetate; aprotic polar solvents such as N,N-dimethylformamide; and chlorinated hydrocarbon solvents such as dichloromethane and chloroform. These solvents can be used alone or in combination of two or more.

[0061] The amount of the solvent used is not particularly limited, but from the viewpoint of productivity, such as production efficiency, the amount is preferably 0 to 1,000 parts by mass, and more preferably 0 to 300 parts by mass, per 100 parts by mass of the total of the organosilane compound or organopolysiloxane compound having an aliphatic unsaturated monovalent hydrocarbon group, such as an alkenyl group or an alkynyl group, represented by the above formula (6) or (7), and the organosilane compound or organopolysiloxane compound having a silicon-bonded hydrogen atom, represented by the above formula (5) or (8).

[0062] The reaction temperature in the hydrosilylation addition reaction is not particularly limited, and the reaction can be carried out from room temperature (23°C±15°C) under heating, with room temperature (23°C±15°C) to 200°C being preferred. To obtain an appropriate reaction rate, the reaction is more preferably carried out under heating, and when the reaction is carried out under heating, the reaction temperature is more preferably 40 to 110°C, and even more preferably 40 to 90°C. The reaction time is also not particularly limited, and is preferably 1 to 60 hours, more preferably 1 to 30 hours, and even more preferably 1 to 20 hours.

[0063] After completion of the reaction, unreacted compounds, the solvent, the platinum compound-containing catalyst, etc. can be removed by methods such as distillation, adsorption, filtration, washing, and purification to obtain the cyclic organopolysiloxane compound represented by general formula (3).

[0064] Examples of the compound represented by the general formula (3) thus obtained include those represented by the following formulae, but are not limited thereto. [ka] (In the formula, k is an integer of 0 to 2, m is an integer of 3 to 6, k+m is an integer of 3 to 8, and n is an integer of 0 to 100.)

[0065] Specific examples of the compound represented by the general formula (3) thus obtained include the following compounds, but are not limited to these. [ka] [ka]

[0066] The blending amount of component (F) is 0.1 to 10 parts by mass, and preferably 0.2 to 8 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than 0.1 part by mass, a cured product exhibiting sufficient durability will not be obtained, whereas if the blending amount exceeds 10 parts by mass, the cured product will be too hard, which is economically disadvantageous.

[0067] [Other ingredients] In addition, in the room temperature curable organopolysiloxane composition for automotive long-life coolant seal of the present invention, generally known additives other than the components (A) to (F) may be used within the scope of the present invention. Examples of additives include polyether as a thixotropy improver, silicone oil as a plasticizer, isoparaffin, etc., and, if necessary, colorants such as pigments, dyes, and fluorescent whitening agents, and biologically active additives such as antifungal agents, antibacterial agents, and marine organism repellents can be added. In addition, surface modifiers such as phenyl silicone oil, fluorosilicone oil, and organic liquids incompatible with silicone as bleed oils can also be added. It is also possible to add silicone resins and their solutions that are generally used to improve LLC resistance.

[0068] [Method for producing room temperature curable organopolysiloxane composition for long-life automotive coolant seals] The room-temperature-curable organopolysiloxane composition for use in long-life automotive coolant seals of the present invention described above can be prepared by uniformly mixing the above components (A) to (F) and, if necessary, other components by a known method. For example, it may be produced by the following procedure. That is, first, 100 parts by mass of the above component (A) and 1 to 500 parts by mass of the component (B) are mixed, and then 0.1 to 50 parts by mass of the above component (C), 0.01 to 20 parts by mass of the component (E), and 0.1 to 10 parts by mass of the component (F) are added to the mixture of components (A) and (B) (if other additives are added, add them at this time) and mixed under reduced pressure. Then, 0.01 to 10 parts by mass of the above component (D) is further added and mixed under reduced pressure to obtain the room temperature curable organopolysiloxane composition for automotive long-life coolant seal of the present invention.

[0069] The room temperature curable organopolysiloxane composition for automotive long-life coolant seal of the present invention has a residual amount of VOC (volatile organic chemicals, such as toluene, xylene, benzene, hexane, heptane, octane, nonane, decane, etc.) in the composition of preferably 5,000 ppm or less, more preferably 1,000 ppm or less, and particularly preferably below the detection limit (substantially 0 ppm). The residual amount of VOC in the composition can be measured by headspace gas chromatography. In order to reduce the residual amount of VOC in the composition to 5,000 ppm or less, it is desirable to reduce the VOC contained in the composition raw materials as much as possible before preparing (blending) the composition, or to use raw materials that do not contain VOC.

[0070] The room temperature curable organopolysiloxane composition for automobile long-life coolant seal of the present invention is a room temperature curable composition, and its curing conditions are not limited as long as the action and effect of the present invention can be obtained. For example, the room temperature curable organopolysiloxane composition for automobile long-life coolant seal of the present invention is poured into a mold with a depth of 2 mm, and cured at 23°C and 50% RH for 7 days, to obtain a cured product (silicone rubber sheet) of the room temperature curable organopolysiloxane composition for automobile long-life coolant seal of the present invention having a thickness of 2 mm.

[0071] Furthermore, the room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals of the present invention can be used as an automotive long-life coolant sealant. This sealant has good curability and can be suitably used as an automotive LLC sealant (cured product) by curing, and is particularly excellent in LLC resistance and heat resistance as well as in adhesiveness.

[0072] Furthermore, the room temperature curable organopolysiloxane composition for sealing automobile long-life coolants of the present invention, when cured, preferably gives a cured product in which, compared to the initial state, the rate of change in tensile strength and elongation at break after an LLC resistance test in which the composition is immersed in an automobile long-life coolant at 120° C. for 240 hours is −50% or more and 100% or less, particularly −30% or more and 70% or less, and the rate of change in tensile strength and elongation at break after a heat resistance test at 120° C. for 1,000 hours is −50% or more and 50% or less, particularly −20% or more and 30% or less. In this case, the room temperature curable organopolysiloxane composition for sealing automobile long-life coolants of the present invention is particularly suitable as a sealant for automobile long-life coolants, and the cured product (silicone rubber cured product) of the room temperature curable organopolysiloxane composition for sealing automobile long-life coolants of the present invention is particularly suitable as a sealant for automobile long-life coolants. In order to bring the rate of change in tensile strength and elongation at break after the LLC resistance test into the above-mentioned ranges, this can be achieved by blending in the composition of the present invention 0.1 to 10 parts by mass of a cyclic organopolysiloxane compound of component (F) having a silanol group-containing organopolysiloxane structure represented by general formula (3) above in its side chain, per 100 parts by mass of the organopolysiloxane of component (A) which is the base polymer. EXAMPLES

[0073] The present invention will be described in more detail below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples. The number average molecular weight and number average degree of polymerization are polystyrene-equivalent number average molecular weight and number average degree of polymerization measured by GPC using toluene as a developing solvent.

[0074] Synthesis of cyclic organopolysiloxane compounds [Synthesis Example 1] Synthesis of cyclic organopolysiloxane compound 1 Into a 500 mL separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 34.4 g (0.1 mol, alkenyl group amount: 0.4 mol) of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane and 0.15 g of a toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (platinum atomic weight: 6.8 × 10 -6 mol) and 50 g of toluene were placed in the flask and heated to 80°C. 119.5 g (SiH group amount: 0.4 mol) of an organopolysiloxane having a silicon atom-bonded hydrogen atom (SiH group) at one end of the molecular chain represented by the following formula (9) and a silanol group (a hydroxyl group bonded to a silicon atom) at the other end was added dropwise thereto, and the mixture was heated and stirred at 80°C for 3 hours. It was confirmed by gas chromatography measurement that the peak derived from the organopolysiloxane having a silicon atom-bonded hydrogen atom at one end of the molecular chain of the raw material had completely disappeared, and the reaction was terminated. After the reaction was terminated, the mixture was subjected to reduced pressure distillation (120°C, 5 mmHg) for 2 hours and filtered to obtain 151.4 g of a cyclic organopolysiloxane compound 1 (number average molecular weight: 1,571) represented by the following formula (10). [ka] [ka]

[0075] [Synthesis Example 2] Synthesis of cyclic organopolysiloxane compound 2 Into a 500 mL separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 40.9 g (0.1 mol, alkenyl group amount: 0.4 mol) of vinyl(dimethyl)hydroxysilane represented by the following formula (11), 0.15 g of a toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (platinum atomic weight: 6.8 × 10 -6mol) and 50 g of toluene were added and heated to 80°C. 24.1 g of 1,3,5,7-tetramethyl-1,3,5,7-tetrahydrogencyclotetrasiloxane (SiH group amount: 0.4 mol) was added dropwise thereto, and the mixture was heated and stirred at 80°C for 3 hours. The reaction was terminated when it was confirmed by gas chromatography that the peak derived from the raw material organopolysiloxane having an alkenyl group had completely disappeared. After the reaction was terminated, the mixture was distilled under reduced pressure (120°C, 5 mmHg) for 2 hours and filtered to obtain 64.3 g of cyclic organopolysiloxane compound 2 (number average molecular weight: 651) represented by the following formula (12). [ka] [ka]

[0076] Next, a room temperature curable organopolysiloxane composition was prepared using the cyclic organopolysiloxane compound. Examples and comparative examples are shown below. In all of the examples and comparative examples, a planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) was used as an appropriate mixer. Mixing was performed at a temperature condition of 25°C for the required time until the components were mixed homogeneously. Unless otherwise specified, physical properties such as viscosity are shown as values ​​at 23°C. Viscosity is a value measured using a rotational viscometer.

[0077] [Example 1] To 100 parts by mass of (A) dimethylpolysiloxane (number average degree of polymerization: approximately 620) having a viscosity of 20,000 mPa s at 23°C and both molecular chain terminals blocked with silanol groups (hydroxyl groups bonded to silicon atoms), 100 parts by mass of (B-1) heavy calcium carbonate the surface of which has been treated with a fatty acid (product name: MC Coat P-20, manufactured by Maruo Calcium Co., Ltd.) and 10 parts by mass of (B-2) powdered carbon black (Denka Black Li-100, manufactured by Denka Co., Ltd., a hydrophobic carbon black with an untreated surface) were added and mixed, and then 9 parts by mass of (C) vinyltris[(cyclopent-1-en-1-yl)oxy]silane, 0.5 parts by mass of (E) tetramethylguanidylpropyltrimethoxysilane, and 1 part by mass of (F) the cyclic organopolysiloxane compound 1 were added and mixed under reduced pressure. Finally, 1 part by mass of (D) γ-aminopropyltrimethoxysilane was added and mixed until the entire mixture was uniform, thereby obtaining composition 1.

[0078] [Example 2] Composition 2 was produced in the same manner as in Example 1, except that the cyclic organopolysiloxane compound 1 of the component (F) was changed to a cyclic organopolysiloxane compound 2 (1 part by mass).

[0079] [Example 3] Composition 3 was produced in the same manner as in Example 1, except that the component (C) vinyltris[(cyclopent-1-en-1-yl)oxy]silane was changed to vinyltriisopropenoxysilane (9 parts by mass).

[0080] [Example 4] Composition 4 was produced in the same manner as in Example 2, except that the component (C) vinyltris[(cyclopent-1-en-1-yl)oxy]silane was changed to vinyltriisopropenoxysilane (9 parts by mass).

[0081] [Example 5] (A) 100 parts by mass of dimethylpolysiloxane (number average degree of polymerization: about 620) with a viscosity of 20,000 mPa·s at 23°C and both ends of the molecular chain are blocked with silanol groups (hydroxyl groups bonded to silicon atoms), (B-1) 100 parts by mass of heavy calcium carbonate (trade name: MC Coat P-20, Maruo Calcium Co., Ltd.) with a surface treated with a fatty acid, (B-2) 10 parts by mass of powdered carbon black (Denka Black Li-100, Denka Co., Ltd., surface-untreated hydrophobic carbon black), were added and mixed, and then 9 parts by mass of (C) vinyltris(methylethylketoxime)silane, 0.1 parts by mass of (E) dioctyltin dilaurate, and (F) 1 part by mass of the cyclic organopolysiloxane compound 1 were added and mixed under reduced pressure. Finally, 1 part by mass of (D) γ-aminopropyltrimethoxysilane was added and mixed until the whole was uniform, to obtain composition 5.

[0082] [Example 6] Composition 6 was produced in the same manner as in Example 5, except that the cyclic organopolysiloxane compound 1 of the component (F) was changed to cyclic organopolysiloxane compound 2 (1 part by mass).

[0083] [Comparative Example 1] Composition 7 was prepared in the same manner as in Example 1, except that the cyclic organopolysiloxane compound 1, component (F), was not added.

[0084] [Comparative Example 2] Composition 8 was prepared in the same manner as in Example 5, except that cyclic organopolysiloxane compound 1, component (F), was not added.

[0085] [Comparative Example 3] (A) 100 parts by mass of dimethylpolysiloxane (number average degree of polymerization: approximately 620) whose molecular chain is terminated at both ends with silanol groups (hydroxyl groups bonded to silicon atoms) and whose viscosity at 23°C is 20,000 mPa s, and SiO 4 / 2 Units and Me 3 SiO 1 / 2 It consists of the unit SiO 4 / 2 Me for units 3 SiO 1 / 2After mixing 20 parts by mass of a 50% by mass toluene solution of a three-dimensional network-structure organopolysiloxane resin having a unit molar ratio of 0.71, a molecular weight of about 5,400, and a silanol group content of 0.096 mol / 100 g, (B-1) heavy calcium carbonate whose surface is treated with fatty acid (trade name: MC Coat P-20, manufactured by Maruo Calcium Co., Ltd.) and (B-2) powdered carbon black (Denka Black Li-100, manufactured by Denka Co., Ltd., surface-untreated hydrophobic carbon black) are added and mixed, and then 9 parts by mass of (C) vinyltriisopropenoxysilane and 0.5 parts by mass of (E) tetramethylguanidylpropyltrimethoxysilane are added and mixed under reduced pressure. Finally, 1 part by mass of (D) γ-aminopropyltrimethoxysilane is added and mixed until the whole is uniform, to obtain composition 9.

[0086] [Test Method] Each of the compositions 1 to 9 (room-temperature-curable organopolysiloxane compositions) prepared in the above Examples 1 to 6 and Comparative Examples 1 to 3 was poured into a mold with a depth of 2 mm and cured at 23°C and 50% RH for 7 days to obtain a 2 mm-thick rubber sheet (a cured product of the room-temperature-curable organopolysiloxane composition).

[0087] The tack-free time (touch-dry time) was measured according to the method specified in JIS A 5758, and the rubber properties (hardness, elongation at break, tensile strength) of a 2 mm thick sheet were measured according to JIS K 6249.

[0088] The hardening speed test was carried out by filling each of Compositions 1 to 9 into a glass petri dish having an inner diameter of 10 mm, leaving it at rest at 23° C. and 50% RH for one day, and then measuring the hardened thickness from the part exposed to air.

[0089] The initial sealability (pressure resistance) test method was performed by using a pressure vessel similar to the flange pressure vessel for pressure resistance test specified in JIS K 6820 as a test device and performing a pressure resistance test. The pressure vessel was composed of an upper vessel having an upper flange with an inner diameter of 58 mm, an outer diameter of 80 mm, and a thickness of 10 mm, and a lower vessel having a lower flange with the same dimensions as the upper flange, and a ring-shaped notch with a width of 3 mm and a depth of 3 mm was provided along the circumference at the inner side edge of the sealing surface of the lower flange. The sealing surface of this lower flange was washed with toluene. Then, the composition was applied in a bead shape to the center of the lower sealing surface in an amount sufficient to fully fill the sealing surface. Immediately after application, the upper vessel was placed on the lower vessel so that the sealing surfaces of the upper and lower flanges were in contact with each other, and an iron spacer with a height of 20.50 mm (in the thickness direction of the flange) to define the distance between the sealing surfaces of the upper and lower flanges was installed, and four tightening bolts were installed. The spacer creates a gap of 0.5 mm between the sealing surfaces, which is intended to make the pressure resistance test for the sealant more severe, i.e., to make it an accelerated test. After curing for 30 minutes at 23°C and 50% RH, gas was introduced from the upper pressure port, and the gas pressure that the sealant, which is the cured product of the above composition, could withstand was measured, and it was confirmed to be 400 kPa or more.

[0090] In addition, from these compositions, aluminum test pieces with a width of 25 mm and a length of 100 mm were used, and test pieces of the same material were bonded to each other using compositions 1 to 9, with an adhesive area of ​​each test piece of 2.5 mm 2 Shear adhesion test specimens were prepared with a bond thickness of 1 mm and aged for 7 days at 23°C and 50% RH. Using these test specimens, the shear adhesive strength to aluminum and the cohesive failure rate were measured according to the method specified in JIS K 6249, and the cohesive failure rates were compared.

[0091] In addition, to confirm the LLC resistance performance, silicone rubber sheets and shear adhesion test specimens, which are the cured products of the obtained compositions 1 to 9, were immersed in a 50% by mass solution of long-life coolant in tap water [product name: Toyota Super Long Life Coolant] and left in a pressure-resistant container at 120°C for 240 hours to deteriorate the cured products in the sheets and test specimens. After that, the same tests as those performed at the initial stage of production were performed to measure the rubber properties (hardness, elongation at break, tensile strength), shear adhesion strength and cohesive failure rate, and a confirmation test of the LLC resistance performance was performed.

[0092] Furthermore, to confirm the heat resistance performance, silicone rubber sheets and shear adhesion test pieces, which are the cured products of the obtained compositions 1 to 9, were heated at 120°C for 1,000 hours to deteriorate the cured products in the sheets and test pieces. Then, by carrying out the same tests as in the initial production stage, the rubber properties (hardness, elongation at break, tensile strength), shear adhesion and cohesive failure rate were measured, and a test to confirm the heat resistance performance was carried out.

[0093] In addition, the toluene content was measured as the residual VOC amount for the obtained compositions 1 to 9. Here, the toluene content was measured using a headspace gas chromatograph (Aglient 7697A manufactured by Agilent Technologies) under the following conditions: column; HP-5MS (length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 μm), carrier gas; He (1.0 mL / min), column temperature; 50°C-10°C / min-280°C, heating condition; 100°C x 20 minutes. Note that when the toluene content was below the detection limit (less than 10 ppm), it was set to 0.

[0094] The results are shown in Table 1 below.

[0095] [Table 1]

[0096] In the test using the compositions of Examples 1 to 6, good LLC resistance performance, heat resistance performance, adhesion, and fast curing (initial sealability) were shown. On the other hand, in the test using the compositions of Comparative Examples 1 and 2, since the composition did not contain a component that improves LLC resistance performance, the rubber properties and adhesion were significantly reduced after the LLC resistance test. In addition, in the test using the composition of Comparative Example 3, the LLC resistance was improved by adding the silicone resin component, but not as much as in the examples of the present invention, and a decrease in curing properties was also confirmed. Furthermore, the condensation reaction of the remaining silanol groups of the resin component resulted in a decrease in the elongation rate after the LLC resistance test and heat resistance test, and it was found that toluene, a deleterious substance, remained in the composition because the silicone resin dissolved in an organic solvent (toluene) was used.

[0097] From the above results, it was found that the room-temperature-curable organopolysiloxane composition of the present invention for use in long-life automotive coolant seals exhibits fast curing properties (initial sealing properties), and furthermore, the cured product exhibits good LLC resistance, heat resistance, and adhesion, making it effective for use in automotive LLC seals.

Claims

1. (A) 100 parts by mass of an organopolysiloxane having a viscosity of 2,000 mPa·s or more at 23° C. and represented by the following general formula (1): HO-(SiR 1 2 O) a -+ (1) (In formula (1), 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. a is an integer of 100 or more. (B) Inorganic filler: 1 to 500 parts by mass, (C) a hydrolyzable organosilane compound having at least three hydrolyzable groups bonded to silicon atoms in one molecule other than the components (A) and (D) and / or a partial hydrolysis condensate thereof: 0.1 to 50 parts by mass, (D) a silane coupling agent represented by the following general formula (2) and / or a partial hydrolysis condensate thereof other than the component (A): 0.01 to 10 parts by mass, R 2 R 3 b SiX 1 3-b (2) (In formula (2), R 2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one atom selected from a nitrogen atom, a sulfur atom, and an oxygen atom; R 3 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms; X 1 is a hydrolyzable group; b is 0, 1 or 2; (E) curing catalyst: 0.01 to 20 parts by mass, and (F) a cyclic organopolysiloxane compound represented by the following general formula (3): 0.1 to 10 parts by mass 【Chemistry 1】 (In the formula, R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, R 5 are independently a hydrogen atom or an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms; R 6 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms excluding aliphatic unsaturated bonds, A is independently a divalent hydrocarbon group having 2 to 8 carbon atoms, k is an integer from 0 to 2, m is an integer from 3 to 6, k+m is an integer from 3 to 8, and n is an integer from 0 to 100. A room-temperature curable organopolysiloxane composition for use in long-life automotive coolant seals, comprising:

2. 2. The room-temperature-curable organopolysiloxane composition for use in long-life automotive coolant seals according to claim 1, wherein the inorganic filler of component (B) is at least one selected from the group consisting of calcium carbonate, fumed silica, precipitated silica and aluminum oxide, which has been hydrophobized with a surface treatment agent, or carbon black.

3. 2. The room-temperature-curable organopolysiloxane composition for use in long-life automotive coolant seals according to claim 1, wherein the residual VOC content in the composition is 5,000 ppm or less.

4. 2. The room-temperature-curable organopolysiloxane composition for automotive long-life coolant seals according to claim 1, which gives a cured product in which, compared to the initial state, the rate of change in tensile strength and elongation at break after an LLC resistance test in which the product is immersed in an automotive long-life coolant at 120°C for 240 hours is from -50% to 100%, and the rate of change in tensile strength and elongation at break after a heat resistance test at 120°C for 1,000 hours is from -50% to 50%.

5. A long-life automotive coolant sealant comprising the room-temperature curable organopolysiloxane composition for use in automotive long-life coolant seals according to any one of claims 1 to 4.

6. A long-life automobile coolant sealant obtained by curing the automobile long-life coolant sealant according to claim 5.

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