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

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, and particularly to a room-temperature-curable organopolysiloxane composition for automotive long life coolant (hereinafter also referred to as LLC) sealing, which is suitably used as an automotive long life coolant sealing material (automotive long life coolant sealant). More particularly, the present invention relates to the room-temperature-curable organopolysiloxane composition for automotive LLC sealing, which has good curability, is excellent in LLC resistance and heat resistance, and provides a cured product (silicone rubber) having good adhesiveness, an automotive long life coolant sealant composed of the composition, and an automotive long life coolant sealing material (automotive long life coolant sealant) obtained by curing the sealant. [Background Art]

[0002] Conventionally, gaskets and packing materials made of cork, organic rubber, asbestos and the like have been used as sealing materials around automotive LLC. However, these conventional gaskets and packing materials have disadvantages that inventory management and working processes are complicated, and further have the drawback that their sealing performance is unreliable. In order to solve these drawbacks, as an LLC sealing material, a room-temperature-curable organopolysiloxane composition formed by a Formed In Place Gasket (FIPG) method (liquid gasket) has been employed.

[0003] In recent years, for the purpose of improving the performance of coolants, various additives have been blended into LLC. And higher LLC resistance performance is required for FIPG. LLC is basically used by being mixed with water. Therefore, automotive LLC sealing materials need to withstand high-temperature conditions in the presence of a highly aggressive chemical, that is, a mixture of LLC and water.

[0004] Japanese Patent Publication No. 2002-226708 (Patent Document 1) reports that the LLC resistance performance can be improved by adding a hydrophobically treated filler to a two-component mixed FIPG. However, a drawback of two-component mixed FIPG is that the mixing process is added, making control in the production process complicated. Furthermore, Japanese Patent Publication No. 2016-199687 (Patent Document 2) reports that the LLC resistance performance can be improved by adding an adhesion promoter with high water resistance. However, in recent years, there has been a demand for improved LLC resistance performance under conditions more severe than immersion conditions of 100°C for 168 hours.

[0005] Furthermore, as reported in Japanese Patent Publication No. 2018-184520 (Patent Document 3), it is known that adding an organopolysiloxane resin with a three-dimensional network structure to the composition can improve LLC resistance. However, in compositions to which an organopolysiloxane resin with a three-dimensional network structure has been added, the remaining silanol groups undergo a condensation reaction, making it unavoidable that the rubber's elongation rate will decrease when exposed to high-temperature environments.

[0006] Furthermore, from the perspective of increasing environmental protection in recent years 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] Japanese Patent Publication No. 2002-226708 [Patent Document 2] Japanese Patent Publication No. 2016-199687 [Patent Document 3] Japanese Patent Publication No. 2018-184520 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention has been made in view of the above circumstances, and aims to provide a room-temperature curable organopolysiloxane composition for automotive long-life coolant seals that has good curability, excellent LLC resistance and heat resistance, and good adhesive properties, and further reduces VOC content, making it suitable as a material for FIPG, an automotive long-life coolant sealant made from the composition, and an automotive long-life coolant sealant (automotive long-life coolant sealant) made by curing the sealant. [Means for solving the problem]

[0009] The inventors of the present invention have conducted extensive research to achieve the above objectives and have found that a room-temperature curable organopolysiloxane composition for automotive long-life coolant seals containing 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 the automotive long-life coolant sealant obtained by curing the sealant. Furthermore, they have found that even without using a three-dimensional network-structured organopolysiloxane resin (so-called silicone resin), the resulting cured product has sufficient LLC resistance and significantly improved heat resistance (reduction in elongation rate when exposed to high temperatures), leading to the present invention.

[0010] Accordingly, the present invention provides the following room-temperature curable organopolysiloxane composition for automotive long-life coolant seals, automotive long-life coolant sealants, and automotive long-life coolant sealant materials (automotive long-life coolant sealants). 1. (A) Organopolysiloxane with a viscosity of 2,000 mPa·s or more at 23°C as shown in the following general formula (1): 100 parts by mass, HO-(SiR 1 20) 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 from each other. 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 3 hydrolyzable groups bonded to a silicon atom in one molecule other than component (A) and component (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) other than component (A) and / or a partial hydrolysis condensate thereof: 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 having at least one atom of one or more kinds 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

Chemical Formula

[0011] The room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention is particularly suitable as an automotive long-life coolant sealant because it provides a cured product (silicone rubber) with good curability, excellent resistance to LLC and heat, and good adhesion, while also having a suppressed VOC content. [Modes for carrying out the invention]

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

[0013] [(A) Ingredient: Organopolysiloxane] The organopolysiloxane of component (A) is represented by the following general formula (1). HO-(SiR 1 20) a -H (1) (In formula (1), R 1 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 (These elements may be identical or different. a is an integer greater than or equal to 100.)

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

[0015] In general formula (1), R 1This refers to unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as 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, these hydrocarbon groups may be partially substituted with halogen atoms such as fluorine, chlorine, or bromine, such as the trifluoropropyl group. 1 The unsubstituted or substituted monovalent hydrocarbon group is preferably one that does not contain an aliphatic unsaturated bond, specifically an alkyl group such as a methyl group, an aryl group such as a phenyl group is preferred, and a methyl group is particularly preferred. 1 These may be the same group or different groups.

[0016] In general formula (1), the main chain consists of bifunctional diorganosiloxane units ((SiR 1 20 2 / 2 The number of repetitions (or degree of polymerization) of )) a may be an integer of 100 or more, preferably an integer between 100 and 2,000, more preferably an integer between 150 and 1,000, and particularly preferably an integer between 200 and 800.

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

[0018] Furthermore, in the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as the number-average degree of polymerization (or number-average molecular weight) in terms of polystyrene in gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF), etc. as the developing solvent. (A) The organopolysiloxane may be one type or two or more types may be used in combination.

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

[0020] Examples of inorganic fillers for component (B) include surface-treated (hydrophobic treatment) or untreated inorganic fillers. Specifically, examples include silica-based fillers such as dry silica (e.g., calcined silica, fumed silica), precipitated silica, and wet silica (e.g., sol-gel silica); carbon black, talc, bentonite, calcium carbonate, zinc carbonate, magnesium carbonate, calcium oxide, zinc oxide, magnesium oxide, aluminum oxide, aluminum hydroxide, etc. Among these, calcium carbonate, fumed silica, precipitated silica, carbon black, and aluminum oxide are preferred. Furthermore, the inorganic filler for component (B) is preferably a hydrophobic inorganic filler, and more preferably calcium carbonate, fumed silica, precipitated silica, aluminum oxide, etc., whose surfaces are hydrophobic, or untreated hydrophobic carbon black. In this case, it is preferable that these inorganic fillers have a low moisture content. There are no particular restrictions on the type, quantity, or method of the surface treatment agent, but typically, known treatment methods using organosilicon compounds such as chlorosilanes, alkoxysilanes, and organosilazanes, as well as fatty acids, paraffins, silane coupling agents, and titanium coupling agents, can be applied.

[0021] (B) The inorganic filler of component (B) may be of one type or two or more types may be used in combination. The amount of component (B) is in the range of 1 to 500 parts by mass per 100 parts by mass of component (A), preferably in the range of 20 to 300 parts by mass. If the amount of component (B) is less than 1 part by mass, the resulting cured product will not have sufficient rubber strength, which is problematic as it will not be suitable for use as an automotive LLC sealant. On the other hand, if it exceeds 500 parts by mass, the discharge performance from the cartridge will deteriorate, storage stability will decrease, and the mechanical properties of the resulting rubber will also decrease.

[0022] [(C) Component: Hydrolyzable organosilane compound and / or partially hydrolyzed condensate thereof] Component (C) acts as a crosslinking agent (curing agent) and is a hydrolyzable organosilane compound and / or a partially hydrolyzed condensate thereof, other than component (A) and components (D) and (F) described later, having at least three (particularly three or four) hydrolyzable groups bonded to silicon atoms in one molecule. The organosilane compound is preferably a hydrolyzable organosilane compound and / or a partially 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 partially hydrolyzing and condensing the organosilane compound). R 7 c SiX 2 4-c (4) (In the formula, R 7 X is an unsubstituted or halogen-substituted monovalent hydrocarbon group, 2 (This is a hydrolyzable group. c is 0 or 1, preferably 1.)

[0023] In general formula (4), X is a hydrolyzable group. 2Examples include ketoxime groups, alkoxy groups, acyloxy groups, and alkenyloxy groups. Specifically, examples include ketoxime groups with 3 to 8 carbon atoms such as dimethylketoxime group, methylethylketoxime group, and methylisobutylketoxime group; alkoxy groups with 1 to 4 carbon atoms, especially 1 or 2 carbon atoms such as methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group; acyloxy groups with 2 to 4 carbon atoms such as acetoxy group and propionoxy group; and alkenyloxy groups with 2 to 5 carbon atoms such as vinyloxy group, allyloxy group, propenoxy group, isopropenoxy group, and cyclopenta-1-en-1-yl)oxy group. 2 These may be the same group or different groups.

[0024] Furthermore, in general formula (4), the remaining group R bonded to silicon atoms other than the hydrolyzable group 7 The monovalent hydrocarbon group is not particularly limited as long as it is unsubstituted or halogen-substituted, but specifically, 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 groups, alkenyl groups such as vinyl groups, and aryl groups such as phenyl groups, and halogen-substituted monovalent hydrocarbon groups such as chloromethyl groups and trifluoropropyl groups, 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 (C) components include ketoxime silanes such as tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutylketoxime)silane, vinyltris(methylethylketoxime)silane, alkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane. Examples include acetoxysilanes such as tiltriacetoxysilane, vinyltriacetoxysilane, and phenyltriacetoxysilane, as well as isopropenoxysilanes such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, and phenyltriisopropenoxysilane, and alkenyloxysilanes such as silyl enol ethers such as methyltris[(cyclopenta-1-en-1-yl)oxy]silane, vinyltris[(cyclopenta-1-en-1-yl)oxy]silane, and phenyltris[(cyclopenta-1-en-1-yl)oxy]silane, and partial hydrolysis condensates of these silanes. These may be used individually or in combination of two or more types.

[0026] Note that component (C) contains (SiR 1 20 2 / 2 ) a (R 1 It is clearly differentiated from component (A) above in that it does not have a repeating structure of linear diorganosiloxane units represented by (a is the same as above) and does not have a silanol group, and is also clearly differentiated from component (D) 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 its molecule, and is also clearly differentiated from component (F) below in that it does not have a cyclic structure and does not have a silanol group.

[0027] The amount of component (C) is used in the range of 0.1 to 50 parts by mass, preferably 5 to 30 parts by mass, per 100 parts by mass of component (A). If the amount is less than 0.1 parts by mass, sufficient crosslinking cannot be obtained, making it difficult to obtain a composition with the desired rubber elasticity, and if it exceeds 50 parts by mass, the resulting cured product tends to have reduced mechanical properties.

[0028] [(D) Component: Silane coupling agent and / or partially hydrolyzed 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 partially hydrolyzed condensate thereof, and is an essential component for exhibiting 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 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms and having at least one atom selected from nitrogen, sulfur, and oxygen atoms, 3 X is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. 1 (This is a hydrolyzable group. b is 0, 1, or 2, preferably 0.)

[0029] In general formula (2), R 2This refers to a monovalent hydrocarbon group having 1 to 20 carbon atoms, which contains at least one functional group (e.g., unsubstituted or substituted amino group, unsubstituted or substituted imino group, amide group, ureido group, mercapto group, epoxy group, (meth)acryloxy group, etc.) excluding a guanidyl group, and which contains an atom selected from nitrogen, sulfur, and oxygen atoms. Specifically, examples include monovalent hydrocarbon groups having 3 to 20 carbon atoms, more preferably 8 to 14 carbon atoms, which contain at least one atom selected from nitrogen, sulfur, and oxygen atoms, such as β-(2,3-epoxycyclohexyl)ethyl group, β-(3,4-epoxycyclohexyl)ethyl group, γ-glycidoxypropyl group, γ-(meth)acryloxypropyl group, γ-acryloxypropyl group, N-β(aminoethyl)-γ-aminopropyl group, γ-aminopropyl group, N-phenyl-γ-aminopropyl group, γ-ureidopropyl group, γ-mercaptopropyl group, γ-isocyanatetopropyl group, etc.

[0030] Furthermore, in general formula (2), R 3 This refers to 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, 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, these hydrocarbon groups may be partially substituted with halogen atoms such as fluorine, chlorine, or bromine, such as trifluoropropyl, with methyl, ethyl, propyl, and isopropyl groups being preferred. 3 These may be the same group or different groups.

[0031] In general formula (2), X is a hydrolyzable group. 1Examples include ketoxime groups, alkoxy groups, alkoxyalkoxy groups, acyloxy groups, alkenyloxy groups, etc. Specifically, examples include ketoxime groups with 3 to 8 carbon atoms such as dimethylketoxime group, diethylketoxime group, methylethylketoxime group, and methylisobutylketoxime group; alkoxy groups with 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms, such as methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group; alkoxyalkoxy groups with 2 to 4 carbon atoms such as methoxymethoxy group and methoxyethoxy group; acyloxy groups with 2 to 4 carbon atoms such as acetoxy group and propionoxy group; and alkenyloxy groups with 2 to 4 carbon atoms such as vinyloxy group, allyloxy group, propenoxy group, and isopropenoxy group. 1 These may be the same group or different groups.

[0032] Examples of the silane coupling agent for component (D) include aminosilanes such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and 3-2-(aminoethylamino)propyltrimethoxysilane; epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; (meth)acryloxypropyltrimethoxysilanes such as γ-(meth)acryloxypropyltrimethoxysilane and γ-(meth)acryloxypropyltriethoxysilane; mercaptosilanes such as γ-mercaptopropyltrimethoxysilane; and isocyanatesilanes such as γ-isocyanatepropyltrimethoxysilane, with γ-aminopropyltrimethoxysilane being preferred. The silane coupling agent and / or its partial hydrolysis condensate of component (D) may be one type or two or more types may be used in combination.

[0033] Furthermore, component (D) differs from components (A) and (C) mentioned above, and component (F) described later, in that it has a monovalent hydrocarbon group having a functional group containing heteroatoms such as nitrogen, oxygen, and sulfur in its molecule.

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

[0035] [(E) component curing catalyst] Component (E) is a curing catalyst. As the curing catalyst, a condensation catalyst that has been commonly used as a curing accelerator for compositions can be used. Examples include organotin compounds such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, dimethyltin dimethoxide, and dimethyltin diacetate; organotitanium compounds such as tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, and dimethoxytitanium diacetylacetonate; and amine compounds such as hexylamine and guanidyl group-containing alkoxysilane compounds such as tetramethylguanidylpropyltrimethoxysilane, as well as salts thereof. One of these can be used alone or in combination of two or more.

[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 will not be obtained. Furthermore, if the amount of component (E) exceeds the upper limit of 20 parts by mass, the adhesion of the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals will decrease, and its shelf life will deteriorate.

[0037] [(F) Component: Cyclic organopolysiloxane compound] Component (F) is a cyclic organopolysiloxane compound having a linear organopolysiloxane structure containing 3 to 6 terminal silanol groups in the side chain via a divalent hydrocarbon group, as shown in the general formula (3) below. 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, it contributes to improving the LLC resistance and curability of the automotive long-life coolant sealant obtained by curing the sealant. [ka] (In the formula, R 4 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, excluding aliphatic unsaturated bonds. 5 R is independently a hydrogen atom or an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms. 6 (where is 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.)

[0038] In general formula (3), R 4 Examples of unsubstituted or substituted monovalent hydrocarbon groups with 1 to 12 carbon atoms, excluding the aliphatic unsaturated bond represented by R, 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-,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 are substituted with halogen atoms such as fluorine, chlorine, or bromine, or cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl. 4Preferably, the groups are lower alkyl groups such as methyl, ethyl, isopropyl, and butyl groups, or aryl groups such as phenyl groups, with methyl and phenyl groups being particularly preferred. 4 These may be the same group or different groups.

[0039] In general formula (3), R 5 Among the hydrogen atoms represented by or aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, examples of aliphatic unsaturated monovalent hydrocarbon groups 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. Among these, R 5 Preferably, the component is a hydrogen atom or an alkenyl group such as a vinyl group or an allyl group, with hydrogen atoms and vinyl groups being particularly preferred. 5 These may be the same group or different groups.

[0040] In general formula (3), R 6 Examples of unsubstituted or substituted monovalent hydrocarbon groups with 1 to 12 carbon atoms, excluding the aliphatic unsaturated bond represented by R, 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-,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 are substituted with halogen atoms such as fluorine, chlorine, or bromine, or cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl. 6 Preferably, the groups are lower alkyl groups such as methyl, ethyl, isopropyl, and butyl groups, or aryl groups such as phenyl groups, with methyl and phenyl groups being particularly preferred. 6These may be the same group or different groups.

[0041] In general formula (3), A is a divalent hydrocarbon group such as an alkylene group or alkenylene group having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, and as a divalent hydrocarbon group, -(CH2) p Alkylene groups such as -(p represents an integer from 2 to 8, preferably from 2 to 4) are preferred. Among these, -CH2CH2- and -CH2CH2CH2- are more preferred. A may be the same group or different groups.

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

[0043] In general formula (3), n is an integer between 0 and 100, preferably between 0 and 20, more preferably between 0 and 10, and even more preferably between 0 and 4.

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

[0045] Specifically, the above formula (5) represents an organohydrogensilane (when n=0 in 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, or an organohydrogenpolysiloxane (when n=1 to 100 in formula (5)) having a silanol group at one end of a molecular chain and a silicon-bonded hydrogen atom at the other end of the molecular chain, and an aliphatic unsaturated monovalent hydrocarbon group (R) such as an alkenyl group or alkynyl group represented by formula (6) 5’ A cyclic organopolysiloxane having ) is subjected to a hydrosilylation addition reaction in the presence of a platinum compound-containing catalyst, or a molecule represented by the above formula (7) is formed, which contains a silanol group and an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or an alkynyl group (R 5’ ) an organosilane having (when n=0 in formula (7)) or an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or alkynyl group at the end of a molecular chain (R 5’An organopolysiloxane having ) and a silanol group at the other end of the molecular chain (in formula (7), when n=1 to 100) and a cyclic organohydrogenpolysiloxane having a silicon atom bonded to a hydrogen atom represented by formula (8) are subjected to a hydrosilylation addition reaction in the presence of a platinum compound-containing catalyst to form an aliphatic unsaturated monovalent hydrocarbon group (R) such as an alkenyl group or an alkynyl group. 5’ By adding a silicon atom-bonded hydrogen atom (SiH group) to ) and forming a carbon-silicon bond (that is, the silicon atom-bonded hydrogen atom (SiH group) in formula (5) and an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or alkynyl group in formula (6) (R 5’ ) an addition reaction with a silicon atom bonded hydrogen atom (SiH group) in formula (8) above and an aliphatic unsaturated monovalent hydrocarbon group (R) such as an alkenyl group or alkynyl group in formula (7) above. 5’ A cyclic organopolysiloxane compound represented by formula (3) is produced by an addition reaction with (a) to form a divalent hydrocarbon group such as an alkylene group and / or an alkenylene group represented by A in formula (3).

[0046] In general formulas (6) and (7), R 5’ As an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R in formula (3) above is an example. 5 Among these, those similar to those exemplified as aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms can be cited. 5’ Preferably, the group is an alkenyl group such as a vinyl group or an allyl group, and a vinyl group is particularly preferred.

[0047] Examples of organohydrogensilanes or organohydrogenpolysiloxanes represented by formula (5) above include those listed below. [ka] (In the formula, n is the same as above.)

[0048] Examples of cyclic organopolysiloxanes represented by formula (6) above include those listed below. [ka]

[0049] Examples of organosilanes or organopolysiloxanes represented by formula (7) above include those listed below. [ka] (In the formula, n is the same as above.)

[0050] Examples of cyclic organohydrogenpolysiloxanes represented by formula (8) above include those listed below. [ka]

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

[0052] Furthermore, considering the need to suppress by-products during the hydrosilylation addition reaction and to enhance the storage stability and properties of the resulting cyclic organopolysiloxane compound, the reaction ratio between the organosilane or organopolysiloxane represented by formula (7) and the cyclic organohydrogenpolysiloxane represented by formula (8) is preferably such that for every 1 mole of hydrosilyl groups (SiH groups) in the cyclic organohydrogenpolysiloxane represented by formula (8), there are 0.5 to 1.5 moles of aliphatic unsaturated monovalent hydrocarbon groups such as alkenyl groups and alkynyl groups in the organosilane or organopolysiloxane represented by formula (7), and more preferably 0.7 to 1.4 moles.

[0053] The platinum compound-containing catalyst used in the above hydrosilylation addition reaction is not particularly limited, and specific examples include chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a toluene or xylene solution of 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 platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex is preferred in terms of regioselectivity for the hydrosilylation addition reaction.

[0054] The amount of platinum compound-containing catalyst used is not particularly limited, but from the standpoint of reactivity and productivity, for 1 mole of an organosilane compound or organopolysiloxane compound having an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or alkynyl group represented by formula (6) or (7) above, the amount of platinum atoms contained is 1 × 10⁶ -7 ~1 × 10 -2 The amount that is in moles is preferably 1 × 10 -7 ~1 × 10 -3 A quantity that is equal to moles is more preferable.

[0055] Furthermore, a co-catalyst may be used to improve the reactivity of the hydrosilylation addition reaction. As this co-catalyst, any co-catalyst commonly used in hydrosilylation addition reactions can be used, 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 amide sulfate, ammonium nitrate, monoammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium diphosphite, ammonium carbonate, ammonium bicarbonate, ammonium sulfide, ammonium borate, and ammonium borofluoride. Among these, ammonium carbonate and ammonium bicarbonate are preferred.

[0057] Specific examples of acid amide compounds include formamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, acrylamide, malonamide, succinamide, maleamide, fumaamide, benzamide, phthalamide, palmitamide, and stearamide. Among these, formamide and stearamide are preferred, with formamide being 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, with acetic acid and trifluoroacetic acid being more preferred.

[0059] The amount of co-catalyst used is not particularly limited, but from the viewpoint of the reactivity, regioselectivity, and cost of the hydrosilylation addition reaction, 1 × 10⁻¹⁶ co-catalyst is used per 1 mole of organosilane compound or organopolysiloxane compound having an aliphatic unsaturated monovalent hydrocarbon group such as an alkenyl group or alkynyl group represented by formula (6) or (7) above. -5 ~1 × 10-1 mol is preferred, 1 × 10 -4 ~5×10 -1 moles are more preferable.

[0060] Although the above hydrosilylation addition reaction can proceed without a solvent, a solvent may also be used. Specific examples of usable solvents 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 may be used individually or in combination of two or more.

[0061] The amount of solvent used is not particularly limited, but from the viewpoint of productivity such as production efficiency, it 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 alkynyl group represented by formula (6) or (7) and the organosilane compound or organopolysiloxane compound having a silicon atom bonded hydrogen atom represented by formula (5) or (8).

[0062] The reaction temperature in the above hydrosilylation addition reaction is not particularly limited and can be carried out at room temperature (23°C ± 15°C) or under heating, but room temperature (23°C ± 15°C) to 200°C is preferred. To obtain a suitable reaction rate, it is even more preferable to carry out the reaction under heating, and when 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, but is preferably 1 to 60 hours, more preferably 1 to 30 hours, and even more preferably 1 to 20 hours.

[0063] After the reaction is complete, unreacted compounds, solvents, platinum compound-containing catalysts, etc., can be removed and purified by methods such as distillation, adsorption, filtration, and washing to obtain a cyclic organopolysiloxane compound represented by general formula (3).

[0064] Examples of compounds represented by the general formula (3) obtained in this manner include, but are not limited to, those represented by the following formulas. [ka] (In the formula, k is an integer between 0 and 2, m is an integer between 3 and 6, k+m is an integer between 3 and 8, and n is an integer between 0 and 100.)

[0065] Furthermore, specific examples of compounds represented by the general formula (3) obtained in this manner include, but are not limited to, the following compounds. [ka] [ka]

[0066] The amount of component (F) is 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, per 100 parts by mass of component (A). If the amount is less than 0.1 parts by mass, a cured product with sufficient durability cannot be obtained, and if the amount exceeds 10 parts by mass, the cured product becomes too hard or is economically undesirable.

[0067] [Other ingredients] Furthermore, the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention may contain generally known additives other than components (A) to (F), as long as they do not impair the objectives of the present invention. Examples of additives include polyethers as thixotropic enhancers, silicone oils and isoparaffins as plasticizers, and, if necessary, colorants such as pigments, dyes, and fluorescent whitening agents, as well as physiologically active additives such as antifungal agents, antibacterial agents, and marine organism repellents. In addition, surface modifiers such as phenyl silicone oil, fluorosilicone oil, and organic liquids incompatible with silicone can also be added as bleed oils. It is also possible to add silicone resins and their solutions, which are generally used to improve LLC resistance.

[0068] [Method for producing a room-temperature curable organopolysiloxane composition for automotive long-life coolant seals] The room-temperature curable organopolysiloxane composition for automotive long-life coolant seals described above can be prepared by uniformly mixing components (A) to (F) above, and other components as needed, by known methods, but it may be manufactured by, for example, the following procedure. Specifically, first, 100 parts by mass of component (A) and 1 to 500 parts by mass of component (B) are mixed. Then, 0.1 to 50 parts by mass of component (C), 0.01 to 20 parts by mass of component (E), and 0.1 to 10 parts by mass of component (F) are added to this mixture of components (A) and (B) (other additives are added at this time if any), and the mixture is mixed under reduced pressure. Finally, 0.01 to 10 parts by mass of component (D) are added and the mixture is mixed under reduced pressure to obtain the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention.

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

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

[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, upon curing, is suitably used as an automotive LLC sealant (cured product). In particular, it exhibits excellent LLC resistance and heat resistance, as well as good adhesion.

[0072] Furthermore, it is preferable that the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention, when cured, yields 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 involving immersion in automotive long-life coolant at 120°C for 240 hours is -50% to 100%, particularly -30% to 70%, 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% to 50%, particularly -20% to 30%. In this case, the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention is particularly suitable as a sealant for automotive long-life coolant, and the cured product (silicone rubber cured product) of the room-temperature curable organopolysiloxane composition for automotive long-life coolant seals of the present invention is particularly suitable as a sealant for automotive long-life coolant. Furthermore, in order to achieve the above-mentioned rate of change in tensile strength and elongation at break after the LLC resistance test, this can be achieved by incorporating a cyclic organopolysiloxane compound of component (F), which has a silanol group-containing organopolysiloxane structure represented by the general formula (3) in its side chain, into the composition of the present invention at a ratio of 0.1 to 10 parts by mass per 100 parts by mass of the organopolysiloxane of component (A), which is the base polymer. [Examples]

[0073] The present invention will be described more specifically 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 expressed as polystyrene equivalents in GPC measurements using toluene as the developing solvent.

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

[0075] [Synthesis Example 2] Synthesis of cyclic organopolysiloxane compound 2 In a 500 mL separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 40.9 g (0.1 mol, alkenyl group weight: 0.4 mol) of vinyl(dimethyl)hydroxysilane represented by formula (11) below, and 0.15 g (platinum atomic weight: 6.8 × 10) of a toluene solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex are added. -650 g of toluene (mol) was added and heated to 80°C. 24.1 g of 1,3,5,7-tetramethyl-1,3,5,7-tetrahydrogencyclotetrasiloxane (SiH group content: 0.4 mol) was added dropwise, and the mixture was heated and stirred at 80°C for 3 hours. Gas chromatography analysis confirmed the complete disappearance of the peak derived from the organopolysiloxane containing the alkenyl group of the starting material, and the reaction was terminated. After the reaction, the mixture was removed by vacuum distillation (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, room-temperature curable organopolysiloxane compositions were prepared using the above-mentioned cyclic organopolysiloxane compounds. Examples and comparative examples are shown below. In all examples and comparative examples, a planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) was used as the appropriate mixer. Mixing was carried out at a temperature of 25°C for the required time until the components were homogeneously mixed. Unless otherwise specified, physical properties such as viscosity are shown as values ​​at 23°C. Viscosity was measured using a rotational viscometer.

[0077] [Example 1] (A) 100 parts by mass of dimethylpolysiloxane (number average degree of polymerization: approximately 620) in which both ends of the molecular chain are sealed with silanol groups (hydroxyl groups bonded to silicon atoms) and has a viscosity of 20,000 mPa·s at 23°C, (B-1) 100 parts by mass of heavy calcium carbonate (product name: MC Coat P-20, manufactured by Maruo Calcium Co., Ltd.) whose surface has been treated with fatty acids, and (B-2) 10 parts by mass of powdered carbon black (Denka Black Li-100, manufactured by Denka Co., Ltd., hydrophobic carbon black with no surface treatment) were added and mixed. Then, (C) 9 parts by mass of vinyltris[(cyclopenta-1-en-1-yl)oxy]silane, (E) 0.5 parts by mass of tetramethylguanidylpropyltrimethoxysilane, 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 mixture was homogeneous to obtain composition 1.

[0078] [Example 2] Composition 2 was prepared in the same manner as in Example 1, except that component (F) cyclic organopolysiloxane compound 1 was replaced with cyclic organopolysiloxane compound 2 (1 part by mass).

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

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

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

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

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

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

[0085] [Comparative Example 3] 100 parts by mass of (A) dimethylpolysiloxane having a viscosity of 20,000 mPa·s at 23°C, both molecular chain terminals of which are blocked with silanol groups (hydroxyl groups bonded to silicon atoms) (number-average degree of polymerization: about 620), and SiO 4 / 2 units and Me3SiO 1 / 2 consisting of units, SiO 4 / 2 Me3SiO relative to units 1 / 2After mixing 20 parts by mass of a 50% by mass toluene solution of a three-dimensional network structure organopolysiloxane resin having a molar ratio of units of 0.71, a molecular weight of approximately 5,400, and a silanol group content of 0.096 mol / 100g, (B-1) 100 parts by mass of heavy calcium carbonate (product name: MC Coat P-20, manufactured by Maruo Calcium Co., Ltd.) with a surface treated with fatty acids and (B-2) 10 parts by mass of powdered carbon black (Denka Black Li-100, manufactured by Denka Co., Ltd., surface-untreated hydrophobic carbon black) were added and mixed, then 9 parts by mass of (C) vinyltriisopropenoxysilane and 0.5 parts by mass of (E) tetramethylguanidylpropyltrimethoxysilane were added and mixed under reduced pressure. Finally, 1 part by mass of (D) γ-aminopropyltrimethoxysilane was added and mixed until the mixture was homogeneous to obtain composition 9.

[0086] [Test Method] The compositions 1 to 9 (room-temperature curable organopolysiloxane compositions) prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were each poured into molds with a depth of 2 mm and cured at 23°C and 50% RH for 7 days to obtain 2 mm thick rubber sheets (cured products of room-temperature curable organopolysiloxane compositions).

[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 the 2 mm thick sheet were measured according to JIS K 6249.

[0088] The curing rate test was performed by filling glass petri dishes with an inner diameter of 10 mm with each of the compositions 1 to 9, leaving them to stand for 1 day at 23°C and 50% RH, and then measuring the thickness of the cured portion exposed to air.

[0089] The initial sealing performance (pressure resistance) test method involved using a pressure vessel similar to the pressure test flange pressure vessel specified in JIS K 6820 as the test apparatus, and performing a pressure resistance test. The pressure vessel consisted of an upper vessel with an upper flange having an inner diameter of 58 mm, an outer diameter of 80 mm, and a thickness of 10 mm, and a lower vessel with a lower flange having the same dimensions as the upper flange. The inner side edge of the sealing surface of the lower flange had an annular notch with a width of 3 mm and a depth of 3 mm along the circumference. The sealing surface of the lower flange was cleaned with toluene. Then, the above composition was applied in a bead-like manner 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, and an iron spacer with a height of 20.50 mm (in the thickness direction of the flanges) was installed to define the distance between the sealing surfaces of the upper and lower flanges, and four tightening bolts were assembled. The spacer creates a 0.5 mm gap between the sealing surfaces, which is intended to make the pressure resistance test on the sealing material more rigorous, a so-called accelerated test. After curing at 23°C and 50% RH for 30 minutes, gas was inserted through the upper pressure port, and the gas pressure that the cured sealing material of the above composition could withstand was measured and confirmed to be 400 kPa or higher.

[0090] Furthermore, using aluminum specimens measuring 25 mm in width and 100 mm in length from these compositions, the adhesive area of ​​each specimen was measured using compositions 1 to 9. 2 Shear adhesion test specimens were prepared by bonding with a bonding thickness of 1 mm and cured at 23°C and 50% RH for 7 days. Using these test specimens, the shear adhesion strength and cohesive failure rate to aluminum were measured according to the method specified in JIS K 6249, and the cohesive failure rates were compared.

[0091] Furthermore, to confirm the LLC resistance performance, the cured silicone rubber sheets and shear adhesion test specimens of 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 the cured materials in the sheets and test specimens were degraded by using a pressure vessel and maintaining a temperature of 120°C for 240 hours. After that, the same tests as in the initial manufacturing stage were performed to measure the rubber properties (hardness, elongation at break, tensile strength), shear adhesion strength, and cohesive failure rate, thereby confirming the LLC resistance performance.

[0092] Furthermore, to confirm the heat resistance performance, the cured silicone rubber sheets and shear adhesion test specimens of compositions 1 to 9 were heated at 120°C for 1,000 hours to degrade the cured material in the sheets and test specimens. Subsequently, tests similar to those performed during the initial manufacturing stage were conducted to measure the rubber properties (hardness, elongation at break, tensile strength), shear adhesion strength, and cohesive failure rate, thereby confirming the heat resistance performance.

[0093] Furthermore, the toluene content was measured as residual VOC content for compositions 1 to 9. Here, the toluene content was measured using a headspace gas chromatograph (Agilent 7697A, manufactured by Agilent Technologies) under the following conditions: column; HP-5MS (length: 30m, inner diameter: 0.25mm, film thickness: 0.25μm), carrier gas; He (1.0mL / min), column temperature; 50℃-10℃ / min-280℃, heating conditions; 100℃ × 20 minutes. In cases where the detection limit (less than 10ppm) was reached, the toluene content was considered to be 0.

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

[0095] [Table 1]

[0096] Tests using the compositions of Examples 1 to 6 showed good LLC resistance, heat resistance, adhesion, and rapid curing (initial sealing). On the other hand, tests using the compositions of Comparative Examples 1 and 2 showed a significant decrease in rubber properties and adhesion after the LLC resistance test because the compositions did not contain any components that improve LLC resistance. Furthermore, in the test using the composition of Comparative Example 3, although LLC resistance was improved by the addition of a silicone resin component, the improvement was not as significant as in the examples of the present invention, and a decrease in curability was also observed. In addition, the condensation reaction of residual silanol groups in the resin component resulted in a decrease in elongation after the LLC resistance test and heat resistance test, and it was found that toluene, a highly toxic substance, remained in the composition because silicone resin dissolved in an organic solvent (toluene) was used.

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

Claims

1. (A) Organopolysiloxane with a viscosity of 2,000 mPa·s or more at 23°C as shown in the following general formula (1): 100 parts by mass, HO-(SiR 1 2 O) a -+ (1) (In formula (1), R 1 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and each R 1 (These elements may be identical or different. a is an integer greater than or equal to 100.) (B) Inorganic filler: 1 to 500 parts by mass, (C) Hydrolyzable organosilane compounds and / or partially hydrolyzed condensates thereof, other than components (A) and (D), having at least three hydrolyzable groups bonded to silicon atoms in one molecule: 0.1 to 50 parts by mass, (D) Silane coupling agent and / or partially hydrolyzed condensate thereof, other than component (A) as shown in the following general formula (2): 0.01 to 10 parts by mass, R 2 R 3 b SiX 1 3-b (2) (In formula (2), R 2 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms and having at least one atom selected from nitrogen, sulfur, and oxygen atoms, 3 X is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, 1 b 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 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, excluding an aliphatic unsaturated bond. 5 R is independently a hydrogen atom or an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms. 6 (A is 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 4 to 8; and n is an integer from 1 to 100.) A room-temperature curable organopolysiloxane composition for automotive long-life coolant seals containing the following:

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

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

4. The room-temperature curable organopolysiloxane composition for automotive long-life coolant seals according to claim 1, which provides 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 automotive long-life coolant at 120°C for 240 hours is -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 -50% to 50%.

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

6. A long-life coolant sealant for automobiles, obtained by curing the long-life coolant sealant for automobiles described in claim 5.

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