Method of dismantling joint member and joint member, and liquid silicone adhesive having easily dismantling property

Abstract

To provide a joint member capable of easily recycling in an extremely short time and with a little consumed energy while exerting sealing performance at room temperature or even after further exposing to a high temperature of 150°C or so, a method of dismantling the joint member, and a liquid silicone adhesive having easily dismantling property used for the joint member.SOLUTION: A method of dismantling a joint member includes a process of separating a plurality of respective members to dismantle a joint member obtained by mutually joining a plurality of respective members with a cured product constituted by curing a curable liquid silicone adhesive including a carbon nanotube having an average diameter of 0.5-50 nm, and a hydroxide compound having a decomposition temperature of 180-600°C where the content of the carbon nanotube is 0.05-3.0 mass% by irradiating the cured product with a microwave having a frequency of 300 MHz or higher and 300 GHz or lower, and an output of 300 W or more and 10,000 W or less for 5 sec. or longer and shorter than 90 sec. to heat the cured product to a decomposition temperature of a hydroxide compound or higher.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for dismantling bonded members that use a curable liquid silicone adhesive, which allows for easy collection, repair, and recycling of automobile parts such as automobile electrical components, electrical and electronic products, etc., in an extremely short period of time; to bonded members that can be used in this method; and to an easily dismantled liquid silicone adhesive. [Background technology]

[0002] In recent years, material recyclability has become increasingly important in a variety of fields due to its environmental friendliness and potential for cost reduction. For recycling purposes, it is necessary to dismantle the components of joined materials, even in the automotive, electrical, and electronics industries. However, reliable sealing performance is also required for joined materials, especially their joints, because they play an important role in preventing the intrusion of external dust and moisture and protecting internal components. Since adhesive sealing provides the best sealing performance, it is necessary to maintain adhesion even under various conditions (heat resistance, humidity resistance, etc.). For this reason, the cured material is usually strongly adhered to the substrate, making it difficult to remove the joined material.

[0003] As a method for recycling bonded members using a curable resin composition, for example, Japanese Patent Application Laid-Open No. 2003-026784 (Patent Document 1) proposes heating bonded members made using a polyol-based curable composition to 150-200°C to soften or liquefy them, and then dismantling the members bonded with the cured product. Japanese Patent Application Laid-Open No. 2002-327163 (Patent Document 2) proposes contacting a halogenated organic solvent with the bonded portion of a bonded structure made using a moisture-curing adhesive primarily composed of a urethane prepolymer to reduce the adhesive strength of the bonded portion, and then peeling and dismantling the constituent members of the bonded structure from the bonded portion. Furthermore, Japanese Patent Application Laid-Open No. 2008-120903 (Patent Document 3) proposes a removable pressure-sensitive adhesive tape that uses an adhesive composed of a vinyl monomer mixture primarily composed of alkyl (meth)acrylate, which maintains high adhesive strength at normal conditions during bonding, but reduces adhesive strength when heated to allow easy separation and dismantling of the bonded portions. Furthermore, Japanese Patent No. 6221630 (Patent Document 4) proposes that by incorporating a tackifier resin into an oxyalkylene polymer, the polymer can be reworked, and can be rebonded even after rework, maintaining its sealing performance.

[0004] On the other hand, silicone adhesives and sealants have superior properties such as heat resistance and weather resistance compared to the above organic adhesives, and are therefore widely used in the automotive, electrical and electronics, construction, etc. However, there is a problem in that silicone adhesives and sealants are difficult to decompose even when heated, making them difficult to repair or recycle.

[0005] Masking silicone adhesives have been proposed as silicone adhesives that allow for easy disassembly of components and exhibit sealing properties. Masking silicone adhesives that do not contain adhesion promoters include silicone adhesives that have release agents added to them to provide releasability for glass and metal. However, when such silicone adhesives are subjected to high temperatures exceeding 200°C, the release agents themselves thermally decompose and lose their effectiveness. The silicone adhesive bonds to the components due to the heat, making disassembly difficult, and recovery and repair are also difficult.

[0006] Furthermore, Japanese Patent Laid-Open Publication No. 2022-183437 (Patent Document 5) proposes a silicone adhesive that uses aluminum hydroxide, but it takes a long time, three hours, to disassemble. International Publication No. 2023 / 054052 (Patent Document 6) proposes that adding particles that generate heat in microwaves to the adhesive and irradiating it with microwaves enables peeling in a short time of 90 to 180 seconds.

[0007] However, there is a demand for demolition that is quicker and more energy-efficient. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-026784 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-327163 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-120903 [Patent Document 4] Patent No. 6221630 [Patent Document 5] Japanese Patent Publication No. 2022-183437 [Patent Document 6] International Publication No. 2023 / 054052 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and aims to provide a joined member in which the joined adhesive members are a cured product of a silicone-based adhesive, and which can be easily recycled in an extremely short time with little energy consumption while maintaining sealing performance at room temperature (23°C±15°C, the same applies hereinafter) and even after being exposed to high temperatures of around 150°C, and a method for dismantling such a joined member, as well as an easily dismantled liquid silicone-based adhesive to be used in such joined members. [Means for solving the problem]

[0010] The present inventors have conducted extensive research into joining members and disassembly methods that consume even less energy and can be recycled in a shorter time than those disclosed in the previously filed International Publication No. 2023 / 054052 (Patent Document 6), and have come up with the following results: In order to improve the efficiency and energy conservation of the recovery, repair, and recycling of electrical and electronic products, etc., carbon nanotubes are added at a specific content to a curable liquid silicone adhesive used as an adhesive for joining members, and a hydroxide compound (particularly a metal hydroxide or a hydroxide of a metal oxide) that decomposes when heated to generate water is further blended into the curable liquid silicone adhesive, thereby forming a joining member (particularly a joining member where multiple (particularly two) members made of organic resin and / or metal are joined together) joined with the cured product. have found that bonded adhesive members (cured products of curable liquid silicone adhesives) retain their sealing properties even after being exposed to room temperature and even to high temperatures of around 150°C, but that their adhesive properties decrease when the cured product is heated to above the decomposition temperature of the hydroxide compound by irradiating it with microwaves at a frequency of 300 MHz to 300 GHz and an output of 300 W to 10,000 W for 5 to 90 seconds. They have also found that irradiating the adhesive member (cured product of curable liquid silicone adhesive) with microwaves under the above conditions allows multiple (particularly two) organic resin and / or metal components to be separated, allowing the bonded components to be easily dismantled in an extremely short time with little energy consumption, and enabling the components to be recycled, thereby completing the present invention.

[0011] Therefore, the present invention provides the following method for dismantling bonded members, bonded members, and easily dismantled liquid silicone adhesive. [1] A method for dismantling a bonded member, comprising: a step of irradiating a bonded member in which a plurality of components are bonded together with a cured product obtained by curing a curable liquid silicone adhesive containing carbon nanotubes having an average diameter of 0.5 to 50 nm and a hydroxide compound having a decomposition temperature of 180 to 600°C, wherein the carbon nanotube content is 0.05 to 3.0 mass %, with microwaves having a frequency of 300 MHz to 300 GHz and an output of 300 W to 10,000 W for 5 seconds to less than 90 seconds, thereby heating the cured product to a temperature above the decomposition temperature of the hydroxide compound, thereby separating the plurality of components and dismantling the bonded member. [2] The method for dismantling joined members according to [1], wherein the curable liquid silicone adhesive is a condensation-curing liquid silicone adhesive or an addition-reaction-curing liquid silicone adhesive. [3] The method for dismantling joined members according to [1] or [2], wherein the carbon nanotubes are multi-walled carbon nanotubes. [4] The method for dismantling joined members according to any one of [1] to [3], wherein the hydroxide compound having a decomposition temperature of 180 to 600°C is at least one selected from aluminum hydroxide, magnesium hydroxide, and aluminum oxide hydroxide (boehmite). [5] The method for dismantling bonded members according to any one of [1] to [4], wherein the content of the hydroxide compound having a decomposition temperature of 180 to 600°C is 35 to 65 mass % of the entire curable liquid silicone adhesive. [6] The method for dismantling bonded members according to any one of [1] to [5], wherein dismantling the bonded members includes a step of peeling off the cured product of the curable liquid silicone adhesive from the plurality of members by hand or with a scraper. [7] The method for dismantling joined members according to any one of [1] to [6], wherein the joined members are automobile parts or electric / electronic parts. [8] A bonded member used in the method for dismantling bonded members according to any one of [1] to [7]. [9] [1] - [7] The method for dismantling a joined member according to any one of [1] to [7], wherein the adhesive is an easily dismantled curable liquid silicone adhesive containing 0.05 to 3.0 mass% of carbon nanotubes having an average diameter of 0.5 to 50 nm, and 35 to 65 mass% of a hydroxide compound having a decomposition temperature of 180 to 600°C, based on the total mass of the adhesive.

[10] An easily dismantlable condensation-curable liquid silicone adhesive used in the method for dismantling bonded members according to any one of [1] to [7], which contains the following components (A) to (F): (A) Carbon nanotubes having an average diameter of 0.5 to 50 nm: 0.05 to 3.0 mass% of the total adhesive; (B) a hydroxide compound having a decomposition temperature of 180 to 600°C: 35 to 65% by mass of the total adhesive; (C) 100 parts by mass of a linear diorganopolysiloxane whose molecular chain ends are blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups, (D) a hydrolyzable organosilane compound having three or more silicon-bonded hydrolyzable groups in the molecule and / or a partial hydrolysis condensate thereof: 0.1 to 40 parts by mass, (E) curing catalyst: 0.001 to 20 parts by mass, and (F) Silane coupling agent: 0.05 to 20 parts by mass.

[11] An easily dismantlable addition reaction curable liquid silicone adhesive used in the method for dismantling joined members according to any one of [1] to [7], which contains the following components (A), (B) and (G) to (I): (A) Carbon nanotubes having an average diameter of 0.5 to 50 nm: 0.05 to 3.0 mass% of the total adhesive; (B) a hydroxide compound having a decomposition temperature of 180 to 600°C: 35 to 65% by mass of the total adhesive; (G) an alkenyl group-containing organopolysiloxane having an alkenyl group bonded to a silicon atom at a molecular chain terminal: 100 parts by mass, (H) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: in an amount such that the number of silicon-bonded hydrogen atoms is 0.01 to 3 moles per mole of silicon-bonded alkenyl groups in component (G), and (I) Platinum group metal catalyst: 0.01 to 1,000 ppm by mass of platinum group metal atoms relative to the total amount of component (G) and component (H). [Effects of the Invention]

[0012] According to the method for dismantling bonded members of the present invention, while maintaining adhesiveness and / or sealing properties from room temperature to high temperatures of around 150°C, the adhesiveness and / or sealing properties of the cured product of the curable liquid silicone adhesive are reduced by microwave irradiation, allowing multiple components, particularly multiple (particularly two) components made of organic resin and / or metal, to be easily separated and dismantled in an extremely short time with little energy consumption, thereby facilitating recycling of the components. Furthermore, the curable liquid silicone adhesive used as the adhesive member for the bonded members is useful as an adhesive or sealing material for joints that require heat resistance and recycling. In the present invention, the "heat resistance temperature" of a member to be dismantled means the upper limit of the temperature at which the member does not undergo thermal decomposition or softening when left standing at a specific temperature for one minute. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The method for dismantling bonded members of the present invention includes a step of irradiating microwaves having a frequency of 300 MHz to 300 GHz and an output of 300 W to 10,000 W for 5 seconds to less than 90 seconds to heat the cured product to a temperature above the decomposition temperature of the hydroxide compound, thereby separating the multiple components, particularly components made of organic resin and / or metal, and dismantling the bonded member, in which multiple components are bonded together with a cured product obtained by curing a curable liquid silicone adhesive containing carbon nanotubes having an average diameter of 0.5 to 50 nm and a hydroxide compound having a decomposition temperature of 180 to 600°C, and the carbon nanotube content being 0.05 to 3.0 mass %.

[0014] [Curable liquid silicone adhesive] The curable liquid silicone adhesive used in the present invention cures to become an adhesive member that bonds multiple components, particularly components made of organic resin and / or metal, and contains carbon nanotubes (A) and a hydroxide compound (B) having a decomposition temperature of 180 to 600°C, the content of said carbon nanotubes (A) is 0.05 to 3.0 mass%, and the adhesive uses a polymer whose main chain is composed of siloxane bonds as the base polymer, and the curing type is preferably a condensation curing type or an addition reaction curing type.

[0015] [Carbon nanotubes] The carbon nanotubes (A) have an average diameter of 0.5 to 50 nm. The carbon nanotubes have a cylindrical shape formed by rolling up graphite (graphene sheet) having a uniform planar structure. Here, single-walled carbon nanotubes or multi-walled carbon nanotubes (double-walled carbon nanotubes wound in two layers or multi-walled carbon nanotubes wound in three or more layers) can be used.

[0016] The average diameter of the carbon nanotubes is 0.5 to 50 nm, preferably 5 to 30 nm. If the average diameter is less than 0.5 nm, the microwave irradiation time required to raise the temperature required for disassembly will be extended, increasing energy consumption. Furthermore, even if the average diameter exceeds 50 nm, the structure is too rigid and difficult to bend, so the microwave irradiation time required to raise the temperature required for disassembly will be extended, increasing energy consumption. The average length of the carbon nanotubes is preferably 1 to 500 μm, more preferably 1 to 100 μm. The average diameter can be measured using a scanning electron microscope (SEM), a laser Raman spectrometer, an X-ray analyzer, or the like, and the average length can be measured using a scanning electron microscope (SEM), a scanning probe microscope (SPM), or the like.

[0017] Although one type of carbon nanotube may be used alone, two or more types of carbon nanotubes having different average diameters, average lengths, etc. may also be used in combination.

[0018] The blending amount of carbon nanotubes is 0.05 to 3.0 mass% of the total curable liquid silicone adhesive, preferably 0.1 to 2.0 mass%, and more preferably 0.2 to 2.0 mass%. If the blending amount is less than 0.05 mass%, the temperature rise of the cured adhesive due to microwave irradiation cannot be expected, and if it exceeds 3.0 mass%, the adhesive becomes hard and workability decreases.

[0019] When adding carbon nanotubes to a curable liquid silicone adhesive, it is preferable to add them directly from the viewpoint of production costs, but a surface treatment agent may also be added. These surface treatment agents may be any known surface treatment agent, such as alkylalkoxysilane, alkylchlorosilane, alkylsilazane, silane coupling agent, titanate treatment agent, or fatty acid ester, and may be used alone or in combination of two or more. Furthermore, surface-treated carbon nanotubes may also be added to the curable liquid silicone adhesive.

[0020] [Hydroxylated compounds with decomposition temperatures of 180 to 600°C] The hydroxide compound (B) having a decomposition temperature of 180 to 600°C is typically preferably a metal hydroxide or a metal oxide hydroxide. The metal is preferably a Group 2 or Group 13 element, with aluminum and magnesium being more preferred. Examples of hydroxide compounds (B) having a decomposition temperature of 180 to 600°C include aluminum hydroxide with a decomposition temperature of around 180°C, magnesium hydroxide with a decomposition temperature of around 300°C, and aluminum oxide hydroxide (boehmite) with a decomposition temperature of around 500°C. The decomposition temperature is preferably 180 to 500°C, more preferably 180 to 400°C. A decomposition temperature below 180°C impairs the heat resistance of the cured product of the curable liquid silicone adhesive, while a decomposition temperature above 600°C takes a long time to disintegrate, consuming significant energy and resulting in inefficiency. The "decomposition temperature" refers to the temperature at which the hydroxide compound begins to decompose and generate water.

[0021] These materials begin to decompose when heated, generating water as a result of the decomposition, which has an anti-flammability effect and has traditionally been used as a flame-retardant material. In the present invention, the water generated by this decomposition is used to generate bubbles in the cured product of the curable liquid silicone adhesive, which reduces the adhesive strength and makes it easy to disassemble the joined components in a short time.

[0022] As the hydroxide compound having a decomposition temperature of 180 to 600°C, particulates having an average particle size of 50 μm or less, preferably 0.5 to 20 μm, are used. If the average particle size is larger than 50 μm, decomposition properties will decrease. The average particle size can be determined as the cumulative weight average value D50 (or median diameter) using a particle size distribution measuring device using a laser light diffraction method or the like.

[0023] The surface of the hydroxide compound may be untreated or may be surface-treated (hydrophobized). When surface treatment is performed, a commonly used treating agent is used, such as a silane coupling agent or a fatty acid. The surface treatment can be carried out by a known method. The amount of treatment is not particularly limited, but is preferably 3% by mass or less (usually 0.1 to 3.0% by mass), particularly preferably 0.2 to 2.0% by mass.

[0024] Although one type of hydroxide compound may be used alone, two or more types having different average particle sizes or surface treatment methods may also be used in combination.

[0025] The content of the hydroxylated compound is 35 to 65 mass% of the total curable liquid silicone adhesive, and preferably 35 to 60 mass%. If it is less than 35 mass%, the decomposition (foaming) of the hydroxylated compound is insufficient and the adhesive strength of the adhesive member does not decrease, while if it is more than 65 mass%, the viscosity of the composition increases, making it difficult to mix and discharge during application.

[0026] [Condensation-curing liquid silicone adhesive] The condensation-curing liquid silicone adhesive contains the above-mentioned (A) carbon nanotubes and (B) a hydroxide compound having a decomposition temperature of 180 to 600°C, and preferably contains, in addition to the above-mentioned components (A) and (B), (C) a linear diorganopolysiloxane (base polymer) whose molecular chain is terminally blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups, (D) a hydrolyzable organosilane compound and / or its partial hydrolysis condensate (crosslinking agent) having three or more silicon-bonded hydrolyzable groups per molecule, (E) a curing catalyst, and (F) a silane coupling agent (adhesion-imparting agent), and is a liquid silicone adhesive that obtains a cured product by utilizing a hydrolysis and condensation reaction caused by moisture (humidity) in the atmosphere at room temperature.

[0027] The organopolysiloxane used as the base polymer (C) is a linear diorganopolysiloxane whose molecular chain is terminated at both ends with silicon-bonded hydroxyl groups (silanol groups) and / or hydrolyzable silyl groups, where the hydrolyzable silyl groups are preferably alkoxysilyl groups or alkoxy-substituted alkoxysilyl groups.

[0028] When a hydroxyl group (silanol group) bonded to a silicon atom is present, it is preferable that each of the molecular chain terminals has one hydroxyl group (that is, a hydroxysilyl group or a silanol group) bonded to a silicon atom.

[0029] When the hydrolyzable silyl group has an alkoxysilyl group or an alkoxy-substituted alkoxysilyl group at the terminal, it is preferable that both ends of the molecular chain have two or three alkoxy groups bonded to silicon atoms (i.e., alkoxysilyl groups) or alkoxy-substituted alkoxy groups bonded to silicon atoms (i.e., alkoxyalkoxysilyl groups) (i.e., they exist as dialkoxyorganosilyl groups or bis(alkoxyalkoxy)organosilyl groups, or trialkoxysilyl groups or tris(alkoxyalkoxy)silyl groups).

[0030] The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, particularly 1 to 4 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a hexyloxy group, and an octyloxy group.

[0031] The alkoxy-substituted alkoxy group is preferably an alkoxy-substituted alkoxy group having 2 to 10 carbon atoms, particularly 2 to 4 carbon atoms, and examples thereof include a methoxyethoxy group, an ethoxyethoxy group, and a methoxypropoxy group.

[0032] As the linear diorganopolysiloxane having both molecular chain terminals blocked with hydroxyl groups and / or hydrolyzable silyl groups bonded to silicon atoms, those having hydroxyl groups (silanol groups), methoxy groups, or ethoxy groups at both terminals, preferably only at both terminals, of the diorganopolysiloxane are particularly preferred.

[0033] Examples of organic groups bonded to silicon atoms other than hydroxyl groups and hydrolyzable groups include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, heptyl, octyl, and 2-ethylhexyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl, tolyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine, or with cyano groups, such as halogenated monovalent hydrocarbon groups such as trifluoropropyl and chloropropyl; and cyanoalkyl groups such as β-cyanoethyl and γ-cyanopropyl. Among these, methyl groups are preferred.

[0034] The viscosity of the organopolysiloxane used as the base polymer (main component) at 23°C is preferably 50 to 1,000,000 mPa·s, and more preferably 100 to 300,000 mPa·s. If the viscosity is below the lower limit, the resulting cured product may not have sufficient mechanical properties, while if it exceeds the upper limit, workability may decrease. In the present invention, the viscosity is the value measured at 23°C using a rotational viscometer (e.g., BL type, BH type, BS type, cone-plate type, rheometer, etc.) (the same applies hereinafter).

[0035] The organopolysiloxane as the base polymer (main component) may be used singly or in combination of two or more.

[0036] (D) The hydrolyzable organosilane compound and / or its partial hydrolysis condensate as a crosslinking agent (curing agent) is a hydrolyzable organosilane compound and / or its partial hydrolysis condensate having three or more silicon-bonded hydrolyzable groups in the molecule (i.e., a siloxane compound such as a siloxane oligomer having three or more residual hydrolyzable groups in the molecule). The hydrolyzable organosilane compound functions as a crosslinking agent (curing agent) in which the three or more hydrolyzable groups in the molecule undergo a hydrolysis and condensation reaction with the linear diorganopolysiloxane base polymer, the molecular chain of which is end-blocked at both ends with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups, to form a crosslinked structure.

[0037] Examples of the hydrolyzable group contained in the hydrolyzable organosilane compound include alkoxy groups, alkoxy-substituted alkoxy groups, acyloxy groups, alkenoxy groups, ketoxime groups, aminoxy groups, and amide groups, all of which have 1 to 10 carbon atoms. Examples include alkoxy groups such as methoxy, ethoxy, and propoxy; alkoxy-substituted alkoxy groups such as methoxyethoxy, ethoxyethoxy, and methoxypropoxy; acyloxy groups such as acetoxy and octanoyloxy; alkenoxy groups such as vinyloxy, isopropenoxy, and 1-ethyl-2-methylvinyloxy; ketoxime groups such as dimethylketoxime, methylethylketoxime, and methylisobutylketoxime; aminoxy groups such as dimethylaminooxy and diethylaminooxy; and amide groups such as N-methylacetamide and N-ethylacetamide.

[0038] The hydrolyzable organosilane compound may have an organic group bonded to a silicon atom other than the above hydrolyzable groups. Examples of such organic groups bonded to a silicon atom other than hydrolyzable groups include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Examples of suitable groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, and octadecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms bonded to carbon atoms in these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine or with cyano groups, such as halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl. Among these, preferred unsubstituted or substituted monovalent hydrocarbon groups are methyl, ethyl, propyl, vinyl, and phenyl.

[0039] Examples of hydrolyzable organosilane compounds and their partial hydrolysis condensates include alkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, decyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane; ketoxime silanes such as methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutylketoxime)silane, and vinyltris(methylethylketoxime)silane; methyltri(methoxymethoxy)silane, ethyltri(methoxymethoxy)silane, vinyltri(methoxymethoxy)silane, and phenyltri(methoxymeth)silane; alkoxy-substituted alkoxysilanes such as methyltris(N,N-diethylaminooxy)silane, methyltris(N-methylacetamido)silane, methyltris(N-butylacetamido)silane, and methyltris(N-cyclohexylacetamido)silane; alkenoxysilanes such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, and phenyltriisopropenoxysilane; acyloxysilanes such as methyltriacetoxysilane and vinyltriacetoxysilane; and partial hydrolysis condensates of these hydrolyzable organosilane compounds.

[0040] The hydrolyzable organosilane compound and / or its partial hydrolysis condensate as a crosslinking agent (curing agent) differ from the above-mentioned component (C) in that they have a viscosity of 20 mPa s or less, and are clearly distinguishable from the silane coupling agent (F) as an adhesion promoter (described later) in that they do not contain in their molecules monovalent hydrocarbon groups substituted with functional groups containing heteroatoms such as nitrogen atoms, oxygen atoms, or sulfur atoms.

[0041] The hydrolyzable organosilane compounds and / or their partial hydrolyzed condensates may be used singly or in combination of two or more.

[0042] The amount of hydrolyzable organosilane compound and / or its partial hydrolysis condensate as a crosslinking agent (curing agent) is 0.1 to 40 parts by mass, preferably 1 to 20 parts by mass, per 100 parts by mass of a linear diorganopolysiloxane whose molecular chain is end-capped with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups. If the amount of hydrolyzable organosilane compound and / or its partial hydrolysis condensate is less than the lower limit (0.1 part by mass), curability and storage stability may be impaired. On the other hand, if the amount exceeds the upper limit (40 parts by mass), not only will it be uneconomical, but the resulting cured product may have reduced elongation and durability.

[0043] The (E) curing catalyst can be a condensation catalyst that has traditionally been used as a curing accelerator for condensation-curable liquid silicone adhesives (room-temperature-curable organopolysiloxane compositions). Examples of such catalysts include organotin compounds such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, dioctyltin dineodecanoate, 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 tetramethylguanidylpropyltrimethoxysilane, as well as salts thereof. These can be used alone or in combination of two or more.

[0044] The amount of curing catalyst added is 0.001 to 20 parts by mass, preferably 0.005 to 5 parts by mass, and more preferably 0.01 to 2 parts by mass, per 100 parts by mass of the linear diorganopolysiloxane having both molecular chain terminals capped with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups. If the amount of curing catalyst added is less than the lower limit (0.001 part by mass), the catalytic effect may not be obtained, whereas if the amount of curing catalyst added exceeds the upper limit (20 parts by mass), not only is it uneconomical, but the durability or adhesiveness of the composition may also decrease.

[0045] The condensation-curing liquid silicone adhesive further contains, as component (F), a silane coupling agent (a hydrolyzable silane compound having in its molecule a monovalent hydrocarbon group substituted with a functional group (excluding guanidyl groups) having a heteroatom such as a nitrogen atom, oxygen atom or sulfur atom, a so-called carbon functional silane compound) that improves adhesive strength and also acts as an adhesive property-imparting component.

[0046] The silane coupling agent used as the adhesion-imparting component is preferably a silane coupling agent known in the art, particularly one having an alkoxy group or an alkenoxy group as the hydrolyzable group, such as methoxy, ethoxy, or propoxy, or alkenoxy groups such as vinyloxy, isopropenoxy, or 1-ethyl-2-methylvinyloxy.

[0047] Furthermore, the monovalent hydrocarbon group substituted with a functional group (excluding guanidyl groups) having a hetero atom such as a nitrogen atom, oxygen atom, or sulfur atom is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms and at least one unsubstituted or substituted amino group, unsubstituted or substituted imino group, mercapto group, epoxy group, or (meth)acryloxy group, and specifically, a γ-acryloxypropyl group, a γ-methacryloxypropyl group, a β-(3,4-epoxycyclohexyl)ethyl group, a γ-glycidoxypropyl group, an N-β(aminoethyl)γ-aminopropyl group, a γ-aminopropyl group, or a group represented by the following formula: [ka] and a γ-mercaptopropyl group.

[0048] The silane coupling agent may have an organic group bonded to the silicon atom other than the monovalent hydrocarbon group substituted with the hydrolyzable group or functional group. The organic group bonded to the silicon atom other than the monovalent hydrocarbon group substituted with the hydrolyzable group or functional group is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, heptyl, and octyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl, tolyl, and xylyl; and aralkyl groups such as benzyl and phenethyl. Among these, methyl and ethyl groups are preferred.

[0049] Specific examples of the silane coupling agent include γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and compounds of the following formula: [ka] Examples include silane compounds represented by the formula (I), γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltriisopropenoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane, etc. In particular, the use of an amino group-containing silane coupling agent is preferred.

[0050] The silane coupling agents may be used alone or in combination of two or more.

[0051] The amount of silane coupling agent (F) added is 0.05 to 20 parts by mass, preferably 0.1 to 15 parts by mass, and particularly preferably 0.5 to 10 parts by mass, per 100 parts by mass of linear diorganopolysiloxane having both molecular chain terminals blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups. If the amount is less than 0.05 parts by mass, sufficient adhesion cannot be obtained, and if the amount is more than 20 parts by mass, the resulting cured product will have poor weather resistance and mechanical properties.

[0052] In addition to the components described above, the condensation-curable liquid silicone adhesive can contain optional components within the scope of the present invention. These optional components include inorganic fillers other than components (A) and (B), colorants such as pigments, dyes, and fluorescent brighteners, antibacterial agents, antifungal agents, and plasticizers such as silicone oil (non-functional organopolysiloxane).

[0053] Specific examples of the optional inorganic filler other than components (A) and (B) include dry process silica (fumed silica, etc.), wet process silica (precipitated silica, etc.), fine quartz powder, diatomaceous earth powder, fine particle alumina, magnesia powder, and fine powder inorganic fillers obtained by surface-treating these with silanes, silazanes, low-polymerization polysiloxanes, etc. (excluding components (A) and (B)). When an inorganic filler other than components (A) and (B) is blended, the blending amount is preferably 0.1 to 800 parts by mass, and more preferably 0.5 to 600 parts by mass, per 100 parts by mass of the linear diorganopolysiloxane having both molecular chain terminals capped with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups.

[0054] The condensation-curing liquid silicone adhesive can be prepared by uniformly mixing the above-mentioned components in a known mixer in a moisture-blocking state (in a dry atmosphere or under reduced pressure) in accordance with conventional methods.

[0055] The resulting condensation-curable liquid silicone adhesive will cure, for example, by leaving it at room temperature (23°C±15°C). The molding method, curing conditions, etc. can be any known method and condition suited to the type of condensation-curable liquid silicone adhesive. For example, the adhesive can be cured by leaving it to stand in the air at 23°C / 50% RH for several hours to several days (e.g., 6 hours to 7 days).

[0056] [Addition reaction curing liquid silicone adhesive] The addition reaction curing liquid silicone adhesive contains, in addition to the above-mentioned (A) carbon nanotubes and (B) hydroxide compound with a decomposition temperature of 180 to 600°C, (G) a linear diorganopolysiloxane (base polymer) whose molecular chain ends are blocked with silyl groups having alkenyl groups such as vinyl groups bonded to silicon atoms, (H) an organohydrogenpolysiloxane (crosslinking agent) having at least two hydrogen atoms bonded to silicon atoms (SiH groups) per molecule, and (I) a platinum group metal catalyst (hydrosilylation addition reaction catalyst), and is a liquid silicone adhesive that crosslinks via an addition reaction (hydrosilylation reaction) of SiH groups to vinyl groups to yield a cured product.

[0057] The alkenyl-containing organopolysiloxane used as the (G) base polymer (main component) is a linear diorganopolysiloxane whose molecular chain ends (one or both ends) are blocked with silyl groups containing an alkenyl group, such as a vinyl group, bonded to a silicon atom, and which has an average of at least one, preferably two or more (usually 2 to 20, particularly 2 to 10, and even more preferably 2 to 5) silicon-bonded alkenyl groups per molecule. Examples of the alkenyl group include lower alkenyl groups typically having 2 to 6 carbon atoms, preferably about 2 to 4 carbon atoms, such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl. The alkenyl group-containing organopolysiloxane used as the base polymer (main component) may have alkenyl groups in side chains on the molecular chain, provided that it has alkenyl groups bonded to silicon atoms at one or both ends of the molecular chain.

[0058] The amount of alkenyl groups contained in the alkenyl group-containing organopolysiloxane of component (G) is preferably 0.001 to 0.08 mol / 100 g, and more preferably 0.002 to 0.06 mol / 100 g. If the amount of alkenyl groups is too small, curing and adhesion may be insufficient, while if the amount is too large, the resulting cured product may have reduced elongation and durability. In the present invention, the amount of alkenyl groups can be measured by a method based on the iodine value measurement method described in JIS K0070.

[0059] Furthermore, the silicon-bonded organic group other than the silicon-bonded alkenyl group is not particularly limited as long as it does not have an aliphatic unsaturated bond, and examples thereof include unsubstituted or substituted monovalent hydrocarbon groups excluding aliphatic unsaturated bonds, typically having 1 to 12 carbon atoms, preferably 1 to 10. Examples of such unsubstituted or substituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms such as chlorine, fluorine, and bromine, such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Alkyl and aryl groups are preferred, and methyl and phenyl groups are more preferred.

[0060] Specific examples of alkenyl group-containing organopolysiloxanes include dimethylpolysiloxanes capped at both ends with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both ends with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymers capped at both ends with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane copolymers capped at both ends with dimethylvinylsiloxy groups, methyltrifluoropropylpolysiloxanes capped at both ends with dimethylvinylsiloxy groups, and dimethylvinylsiloxanes capped at both ends with dimethylvinylsiloxy groups. Siloxy-capped dimethylsiloxane-methyltrifluoropropylsiloxane copolymer, both-end capped dimethylvinylsiloxy-group dimethylsiloxane-methyltrifluoropropylsiloxane-methylvinylsiloxane copolymer, both-end capped dimethylpolysiloxane with methyldivinylsiloxy-groups, both-end capped dimethylsiloxane-methylvinylsiloxane copolymer, both-end capped dimethylsiloxane-diphenylsiloxane copolymer with methyldivinylsiloxy-groups, both-end capped dimethylsiloxane with methyldivinylsiloxy-groups copolymer of methylvinylsiloxane and diphenylsiloxane, copolymer of methyltrifluoropropylpolysiloxane end-blocked with methyldivinylsiloxy groups, copolymer of dimethylsiloxane and methyltrifluoropropylsiloxane end-blocked with methyldivinylsiloxy groups, copolymer of dimethylsiloxane and methyltrifluoropropylsiloxane and methylvinylsiloxane end-blocked with methyldivinylsiloxy groups, copolymer of dimethylpolysiloxane end-blocked with trivinylsiloxy groups, copolymer of dimethylsiloxane and methylvinylsiloxane end-blocked with trivinylsiloxy groups copolymer, dimethylsiloxane-diphenylsiloxane copolymer both ends capped with trivinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane copolymer both ends capped with trivinylsiloxy groups, methyltrifluoropropylpolysiloxane both ends capped with trivinylsiloxy groups, dimethylsiloxane-methyltrifluoropropylsiloxane copolymer both ends capped with trivinylsiloxy groups, dimethylsiloxane-methyltrifluoropropylsiloxane-methylvinylsiloxane copolymer both ends capped with trivinylsiloxy groups,Dimethylpolysiloxane with one end capped with trimethylsiloxy groups and the other with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymer with one end capped with trimethylsiloxy groups and the other with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymer with one end capped with trimethylsiloxy groups and the other with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymer with one end capped with trimethylsiloxy groups and the other with dimethylvinylsiloxy groups Examples include diphenylsiloxane copolymer, methyltrifluoropropylpolysiloxane with one end capped with trimethylsiloxy group and the other end capped with dimethylvinylsiloxy group, dimethylsiloxane-methyltrifluoropropylsiloxane copolymer with one end capped with trimethylsiloxy group and the other end capped with dimethylvinylsiloxy group, and dimethylsiloxane-methyltrifluoropropylsiloxane-methylvinylsiloxane copolymer with one end capped with trimethylsiloxy group and the other end capped with dimethylvinylsiloxy group.

[0061] The viscosity at 23°C of the alkenyl group-containing organopolysiloxane used as the base polymer (main component) is preferably 100 to 500,000 mPa·s, and more preferably 700 to 100,000 mPa·s.

[0062] The alkenyl group-containing organopolysiloxane as the base polymer (main component) may be used either alone or in combination of two or more.

[0063] The organohydrogenpolysiloxane used as the (H) crosslinking agent (curing agent) has, on average, at least two, preferably at least three, more preferably up to 500, even more preferably up to 200, and particularly preferably up to 100 silicon-bonded hydrogen atoms (SiH groups) per molecule, and preferably has no aliphatic unsaturated bonds per molecule.

[0064] In this organohydrogenpolysiloxane, the silicon-bonded organic group other than the silicon-bonded hydrogen atom is not particularly limited, and examples include unsubstituted or substituted monovalent hydrocarbon groups having a carbon atom number of typically 1 to 10, preferably 1 to 6. Specific examples include the same groups as those exemplified as silicon-bonded organic groups other than silicon-bonded alkenyl groups in the description of the alkenyl-group-containing organopolysiloxane, as well as alkenyl groups such as vinyl groups and allyl groups. Preferred are unsubstituted monovalent hydrocarbon groups that do not have an aliphatic unsaturated bond, such as alkyl groups and aryl groups, and more preferably methyl groups, phenyl groups, etc.

[0065] Preferably, the number of silicon atoms in the molecule is 2 to 300, particularly 3 to 150, and particularly about 4 to 100, and the organohydrogenpolysiloxane is liquid at room temperature. The hydrogen atoms bonded to the silicon atoms may be located at either the terminals of the molecular chain, the middle (non-terminal) of the molecular chain, or both. The molecular structure of the organohydrogenpolysiloxane may be linear, cyclic, branched, or three-dimensional network. In the present invention, the degree of polymerization (or the number of repeating diorganosiloxane units constituting the main chain, which is a measure of the number of silicon atoms in the molecule) can be determined as the polystyrene-equivalent number-average degree of polymerization (or number-average molecular weight) by gel permeation chromatography (GPC) analysis using, for example, toluene as a developing solvent.

[0066] The amount of SiH groups contained in the organohydrogenpolysiloxane of component (H) is preferably 0.001 to 0.015 mol / g, and more preferably 0.003 to 0.013 mol / g. If the amount of SiH groups is too small, curing and adhesion may be insufficient, while if the amount of SiH groups is too large, the elongation and durability of the resulting cured product may be reduced. In the present invention, the amount of SiH groups can be measured by adding an alkali to a weighed amount of organohydrogenpolysiloxane and measuring the volume of hydrogen gas generated.

[0067] Examples of organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymer, methylhydrogenpolysiloxane capped with trimethylsiloxy groups at both ends, dimethylsiloxane-methylhydrogensiloxane copolymer capped with trimethylsiloxy groups at both ends, dimethylpolysiloxane capped with dimethylhydrogensiloxy groups at both ends, dimethylsiloxane capped with dimethylhydrogensiloxy groups at both ends, copolymer of methylhydrogensiloxane and methylhydrogensiloxane, copolymer of methylhydrogensiloxane and diphenylsiloxane end-blocked with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, diphenylsiloxane and dimethylsiloxane end-blocked with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, methylphenylsiloxane and dimethylsiloxane end-blocked with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, dimethylsiloxane and diphenylsiloxane end-blocked with dimethylhydrogensiloxy groups, copolymer of methylhydrogensiloxane, dimethylsiloxane and methylphenylsiloxane end-blocked with dimethylhydrogensiloxy groups, (CH3)2HSiO 1 / 2 Units and (CH3)3SiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 and copolymers consisting of these exemplified compounds in which some or all of the methyl groups have been substituted with other alkyl groups, phenyl groups, or the like.

[0068] The organohydrogenpolysiloxanes may be used alone or in combination of two or more.

[0069] The amount of organohydrogenpolysiloxane added is an amount that provides 0.01 to 3 moles, preferably 0.05 to 2.5 moles, and more preferably 0.2 to 2 moles of silicon-bonded hydrogen atoms (SiH groups) per mole of silicon-bonded alkenyl groups in the alkenyl group-containing organopolysiloxane.

[0070] (I) Platinum group metal catalysts (hydrosilylation addition reaction catalysts) are used as catalysts to promote the addition reaction between silicon-bonded alkenyl groups in alkenyl-group-containing organopolysiloxanes and silicon-bonded hydrogen atoms in organohydrogenpolysiloxanes. Known platinum group metal catalysts can be used. Specific examples include platinum-based catalysts such as platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, and complexes of chloroplatinic acid with olefins, aldehydes, vinylsiloxanes, or acetylene alcohols.

[0071] The amount of platinum group metal catalyst added may be an effective amount, which can be increased or decreased as appropriate depending on the desired curing rate, but is usually in the range of 0.01 to 1,000 ppm, preferably 0.1 to 1,000 ppm, and more preferably 1 to 300 ppm, calculated as platinum group metal atoms by mass relative to the total amount of alkenyl group-containing organopolysiloxane and organohydrogenpolysiloxane. If this amount is too high, the heat resistance of the resulting cured product may decrease.

[0072] It is preferable to add (J) a silane coupling agent (a hydrolyzable silane compound having in its molecule a monovalent hydrocarbon group substituted with a functional group having a heteroatom such as an oxygen atom or a sulfur atom, a so-called carbon functional silane compound) to the addition reaction curing liquid silicone adhesive, which further improves adhesive strength and acts as an adhesive property-imparting component.

[0073] The silane coupling agent used as the adhesion-imparting component is preferably a silane coupling agent known in the art, specifically the same silane coupling agents as those exemplified for component (F) above.

[0074] When this silane coupling agent is added, the amount added is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and particularly preferably 0.5 to 10 parts by mass, per 100 parts by mass of the alkenyl group-containing organopolysiloxane (base polymer). If the amount is less than 0.05 parts by mass, sufficient adhesion may not be obtained, while if the amount exceeds 20 parts by mass, the weather resistance and mechanical properties of the resulting cured product may be poor.

[0075] In addition to the above components, the addition reaction curable liquid silicone adhesive can contain optional components within the scope of the present invention. Examples of optional components include reaction inhibitors such as ethynylcyclohexanol, adhesion improvers such as benzophenonetetracarboxylic dianhydride, inorganic fillers similar to those exemplified in the condensation curable liquid silicone adhesives described above (excluding the carbon nanotubes of component (A) and the hydroxide compounds of component (B) whose decomposition temperature is 180 to 600°C), organopolysiloxanes that do not contain silicon-bonded hydrogen atoms (SiH groups) or silicon-bonded alkenyl groups (so-called non-functional silicone oils), heat resistance additives, flame retardants, thixotropic agents, pigments, dyes, etc.

[0076] The addition reaction curing liquid silicone adhesive can be prepared by uniformly mixing the above-mentioned components using a known mixer in accordance with a conventional method.

[0077] The curing conditions for the addition reaction curing liquid silicone adhesive may be 23 to 150°C, particularly 23 to 120°C, for 10 minutes to 8 hours, particularly 30 minutes to 5 hours.

[0078] [Connection material] In the method for dismantling bonded members of the present invention, the bonded members are bonded together by a cured product (an adhesive member made of an adhesive silicone rubber cured product) obtained by curing a curable liquid silicone adhesive containing carbon nanotubes and a hydroxide compound having a decomposition temperature of 180 to 600°C. In the bonded members, the bonded members are preferably the same or different members selected from organic resin members and metal members, and more preferably, at least one of the bonded members is an organic resin member. Examples of such combinations of members include combinations of members made of the same or different organic resins, and combinations of metal members and organic resin members. Examples of organic resins that constitute the organic resin members include polyamide resins such as PBT (polybutylene terephthalate resin), PPS (polyphenylene sulfide resin), PA66 (nylon 66), and PA6 (nylon 6), as well as PC (polycarbonate resin). Examples of metals that constitute the metal members include aluminum, iron, stainless steel, and copper. The organic resin or metal constituting the organic resin member or metal member preferably has a heat resistance temperature of 160° C. or higher.

[0079] [Method of manufacturing joining members] A curable liquid silicone adhesive containing carbon nanotubes and a hydroxide compound with a decomposition temperature of 180 to 600°C is applied by hand or machine to the surface of one of the organic resin or metal components in the shape of a joint (e.g., a gasket), and then the other organic resin or metal component is bonded and cured. The adhesive is then secured in place with bolts, if necessary. When the curable liquid silicone adhesive of the present invention is a condensation-curing liquid silicone adhesive, it cures due to moisture in the air at room temperature, so curing proceeds simply by leaving the components together after bonding. Humidification is effective for accelerating curing. When the curable liquid silicone adhesive of the present invention is an addition-reaction-curing liquid silicone adhesive, it cures via an addition reaction at temperatures of 23 to 150°C, so curing proceeds simply by leaving the components together after bonding or by heating.

[0080] Examples of the joining member include automobile parts such as engines, transmissions, and automobile electrical components (ECUs (Electronic Control Units) and PCUs (Power Control Units)), as well as electric and electronic parts such as smartphones, tablets, liquid crystal displays, and batteries, and automobile parts and electric and electronic parts are preferred.

[0081] The above-mentioned joining member is one that maintains the joined state of the members at an ambient temperature of 150°C or less, preferably at room temperature to 120°C.

[0082] The above-mentioned joining members are preferably easily dismantled, being joined with a certain degree of adhesive strength during normal use, but whose adhesive strength decreases to such an extent that the members can be separated after microwave irradiation. Specifically, the initial shear adhesive strength of the joining members is preferably 0.6 MPa or more, particularly 0.8 MPa or more, and even more preferably 1.0 MPa or more, and the shear adhesive strength of the joining members after microwave irradiation is preferably 0.5 MPa or less, particularly 0.3 MPa or less. This shear adhesive strength is a value measured in accordance with the method specified in JIS K6850. Note that the initial and post-microwave shear adhesive strengths within the above-mentioned ranges can be achieved by adjusting the composition of the curable liquid silicone adhesive to fall within the specific ranges described above.

[0083] [Disassembly method] The method for dismantling bonded members of the present invention involves irradiating a cured product (cured adhesive silicone rubber product) obtained by curing a curable liquid silicone adhesive, which is the adhesive material of the bonded members, with microwaves at a frequency of 300 MHz to 300 GHz and an output of 300 W to 10,000 W for 5 to 90 seconds, heating the cured product to a temperature above the decomposition temperature of the hydroxide compound, and then cooling it to room temperature.The bonded members can be dismantled by either allowing the components to peel off naturally, or by manually applying force or using a tool such as a scraper to peel off multiple (particularly two) components made of organic resin and / or metal.The dismantled components can also be recycled.

[0084] In this case, it is presumed that the following phenomenon occurs in the cured product of the curable liquid silicone adhesive used in the method for dismantling bonded members of the present invention when irradiated with microwaves: (1) When irradiated with microwaves, the carbon nanotubes of component (A) generate heat. (2) The heat generated by the carbon nanotubes of component (A) heats the hydroxide compound of component (B), causing the hydroxide compound of component (B) to decompose and generate water. (3) The generated water is heated by the heat generated by the carbon nanotubes of component (A) and by microwave irradiation, and vaporizes, causing foaming. (4) This foaming in the cured product reduces the adhesive strength of the joining members.

[0085] The microwaves used should be such that the temperature of the cured product of the curable liquid silicone adhesive after irradiation is equal to or higher than the decomposition temperature of the hydroxide compound. The frequency is 300 MHz to 300 GHz, preferably 1 GHz to 100 GHz, and more preferably 1 GHz to 5 GHz. The output is 300 W to 10,000 W, preferably 700 W to 5,000 W. The microwave irradiation time is 5 seconds to less than 90 seconds, and preferably 10 seconds to 80 seconds. [Example]

[0086] Next, the present invention will be specifically explained by showing composition examples, composition comparison examples, and examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the room temperature is 23°C, the viscosity is the value measured at 23°C using a rotational viscometer, the average diameter and average length are values ​​determined using a scanning electron microscope (SEM), and the average particle size is the value determined as the cumulative weight average value D50 (or median diameter) using a particle size distribution measurement device using a laser light diffraction method.

[0087] Preparation of curable liquid silicone adhesive (composition) [Composition Example 1] Composition 1 was obtained by uniformly mixing 100 parts by mass of dimethylpolysiloxane having a viscosity of 5,000 mPa·s and both molecular chain terminals blocked with hydroxyl groups, 1 part by mass of multi-walled carbon nanotubes having an average diameter of 10 to 15 nm and an average length of 10 μm (amount in the entire composition: 0.48% by mass), 100 parts by mass of aluminum hydroxide having an average particle diameter of 10 μm and an untreated surface (amount in the entire composition: 47.8% by mass), 6.5 parts by mass of vinyltriisopropenoxysilane, 0.5 parts by mass of γ-aminopropyltriethoxysilane, 0.5 parts by mass of a compound obtained by the dehydrochlorination reaction of xylylenediamine and 3-chloropropyltrimethoxysilane, as represented by the following formula (1), and 0.7 parts by mass of γ-(N,N,N',N'-tetramethylguanidyl)propyltrimethoxysilane. [ka]

[0088] Composition Example 2 Composition 2 was prepared in the same manner as in Example 1, except that the amount of carbon nanotubes added to Composition 1 was changed to 0.2 parts by mass (0.1% by mass of the total composition) (aluminum hydroxide content of 48.0% by mass of the total composition).

[0089] Composition Example 3 Composition 3 was prepared in the same manner as in Example 1, except that the amount of carbon nanotubes added to Composition 1 was changed to 4.0 parts by mass (aluminum hydroxide content in the entire composition: 47.1% by mass).

[0090] Composition Example 4 The composition contains 100 parts by mass of dimethylpolysiloxane (alkenyl group content: 0.006 mol / 100 g) whose molecular chain ends are blocked with dimethylvinylsilyl groups and whose viscosity is 5,000 mPa·s, 1 part by mass of multi-walled carbon nanotubes having an average diameter of 10 to 15 nm and an average length of 10 μm (content of 0.49% by mass of the entire composition), and 100 parts by mass of aluminum hydroxide whose average particle diameter is 10 μm and whose surface is untreated (content of 49.0% by mass of the entire composition). % by mass), 0.7 parts by mass of an organohydrogenpolysiloxane (SiH group content: 0.0112 mol / g) represented by the following formula (2), 1 part by mass of γ-glycidoxypropyltrimethoxysilane, 1 part by mass of benzophenonetetracarboxylic dianhydride, 0.08 parts by mass of ethynylcyclohexanol, and 0.15 parts by mass of a toluene solution of platinum-divinyltetramethyldisiloxane complex (platinum content 1.0% by mass) were uniformly mixed to obtain composition 4. [ka]

[0091] [Comparative Composition Example 1] An attempt was made to prepare a composition in the same manner as in Example 1, except that the amount of carbon nanotubes added to Composition 1 was changed to 8.0 parts by mass (amount of aluminum hydroxide in the total composition: 3.7% by mass). However, the composition did not become liquid and could not be formulated (aluminum hydroxide amount in the total composition: 46.0% by mass).

[0092] [Comparative Composition Example 2] Composition 5 was prepared in the same manner as in Example 1, except that the carbon nanotubes in Composition 1 were replaced with 3.0 parts by mass of acetylene black powder having an average particle diameter of 35 nm and an untreated surface (aluminum hydroxide content in the entire composition: 47.3% by mass).

[0093] [Comparative Composition Example 3] Composition 6 was prepared in the same manner as in Example 1, except that the aluminum hydroxide of Composition 1 was not added (carbon nanotube content in the entire composition: 0.92 mass%, aluminum hydroxide content in the entire composition: 0 mass%).

[0094] [Examples 1 to 4, Comparative Examples 1 and 2] [Measurement of temperature of cured adhesive by microwave irradiation] One of the curable liquid silicone adhesive compositions 1-6 was applied to a 25 mm wide, 100 mm long glass substrate to a width of 20 mm, length of 80 mm, and thickness of 1 mm. Compositions 1-3, 5, and 6 were cured at 23°C / 50% RH for 7 days, while composition 4 was heated at 120°C for 1 hour to obtain a cured curable liquid silicone adhesive. This cured product was irradiated with microwaves at a frequency of 2.4 GHz and an output of 1,000 W using a microwave irradiation device (manufacturer: Shikoku Keisoku Kogyo, product name: μReactor) for the time listed in Table 1. The temperature of the cured adhesive was then immediately measured using a non-contact radiation thermometer (manufacturer: Keyence, product name: FT-H20). Note that if the measured temperature exceeded 300°C, the substrate melted, making measurement impossible. Therefore, the temperature was recorded as "above 300°C" and no further microwave irradiation was performed. The results are shown in Table 1.

[0095] [Table 1]

[0096] [Production of joining members] Two PBT (polybutylene terephthalate resin, heat resistance temperature: 150°C or higher) substrates with a width of 25 mm and a length of 100 mm were used, and one of the above compositions 1 to 6 was used as the curable liquid silicone adhesive. The adhesive thickness was 1.0 mm and the adhesive area was 2.5 cm. 2 Two PBT substrates were bonded together so that the bonded joint was formed by bonding two PBT substrates together with the cured product of the curable liquid silicone adhesive (cured adhesive silicone rubber product). Compositions 1 to 3, 5, and 6 were cured at 23°C / 50% RH for 7 days, and composition 4 was heated at 120°C for 1 hour.

[0097] Disassembly evaluation The adhesive strength (dismantleability) of the bonded members prepared above was evaluated by the following evaluation method. The results are shown in Table 2.

[0098] (1) Adhesive strength (initial) Using the bonding members prepared above, the shear adhesive strength (initial) of the cured adhesive silicone rubber to the PBT member was measured in accordance with the method specified in JIS K6850.

[0099] (2) Adhesion strength (after microwave irradiation) The bonding members prepared above were irradiated with microwaves at a frequency of 2.4 GHz and an output of 1,000 W using a microwave irradiation device (manufactured by Shikoku Keisoku Kogyo (product name: μReactor)) for the time listed in Table 2, and then cooled to room temperature, and the shear adhesive strength (after microwave irradiation) of the cured adhesive silicone rubber to the PBT member was measured using the same method as in (1) above. In Comparative Example 2, the shear adhesive strength did not decrease after microwave irradiation (irradiation time: 20 seconds), so microwave irradiation was continued for up to 90 seconds. However, when the irradiation time exceeded 20 seconds, the deterioration of the bonding member itself became so severe that it was not possible to measure the shear adhesive strength.

[0100] [Table 2]

[0101] As is clear from the above results, in Examples 1 to 4, because a specific amount of carbon nanotubes was added to the curable liquid silicone adhesive, the temperature of the cured adhesive rose rapidly upon microwave irradiation, which in turn caused the hydroxide compound to decompose, resulting in a decrease in adhesive strength. As a result, resin bonded members bonded with the cured product of the curable liquid silicone adhesive (cured adhesive silicone rubber) could be easily disassembled within 30 seconds, an extremely short time with little energy consumption. On the other hand, in Comparative Example 1, acetylene black powder was added to the curable liquid silicone adhesive instead of carbon nanotubes, so the temperature rise due to microwave irradiation was small, which resulted in a longer time until dismantling and increased energy consumption.In Comparative Example 2, carbon nanotubes were added to the curable liquid silicone adhesive, so the temperature of the cured adhesive rose in a short time, but because no hydroxide compound was added, there was no decrease in adhesive strength and dismantling was not possible.

Claims

1. A method for dismantling a bonded member, comprising: a step of irradiating a cured product of a cured liquid silicone adhesive, in which a plurality of components are bonded together, with a cured product obtained by curing the curable liquid silicone adhesive, which contains carbon nanotubes having an average diameter of 0.5 to 50 nm and a hydroxide compound having a decomposition temperature of 180 to 600°C, and in which the carbon nanotube content is 0.05 to 3.0 mass %, for 5 to 90 seconds with microwaves having a frequency of 300 MHz to 300 GHz and an output of 300 W to 10,000 W, to heat the cured product to a temperature equal to or higher than the decomposition temperature of the hydroxide compound, thereby separating the plurality of components and dismantling the bonded member.

2. 2. The method for dismantling joined members according to claim 1, wherein the curable liquid silicone adhesive is a condensation-curing liquid silicone adhesive or an addition-reaction-curing liquid silicone adhesive.

3. 2. The method for dismantling joined members according to claim 1, wherein the carbon nanotubes are multi-walled carbon nanotubes.

4. 2. The method for dismantling joined members according to claim 1, wherein the hydroxide compound having a decomposition temperature of 180 to 600°C is at least one selected from aluminum hydroxide, magnesium hydroxide, and aluminum oxide hydroxide (boehmite).

5. 2. The method for dismantling joined members according to claim 1, wherein the content of the hydroxide compound having a decomposition temperature of 180 to 600°C is 35 to 65 mass % of the total curable liquid silicone adhesive.

6. 2. The method for dismantling joined members according to claim 1, wherein the dismantling of the joined members includes a step of peeling off the cured liquid silicone adhesive from the plurality of members by hand or with a scraper.

7. 2. The method for dismantling joined members according to claim 1, wherein the joined members are automobile parts or electric / electronic parts.

8. A joined member used in the method for dismantling joined members according to any one of claims 1 to 7.

9. 8. An easily dismantlable curable liquid silicone adhesive used in the method for dismantling joined members according to any one of claims 1 to 7, the adhesive comprising 0.05 to 3.0 mass% of carbon nanotubes having an average diameter of 0.5 to 50 nm, and 35 to 65 mass% of a hydroxide compound having a decomposition temperature of 180 to 600°C, based on the total mass of the adhesive.

10. An easily dismantlable condensation-curing liquid silicone adhesive used in the method for dismantling joined members according to any one of claims 1 to 7, comprising the following components (A) to (F): (A) carbon nanotubes having an average diameter of 0.5 to 50 nm: 0.05 to 3.0% by mass of the total adhesive; (B) a hydroxide compound having a decomposition temperature of 180 to 600°C: 35 to 65% by mass of the total adhesive; (C) 100 parts by mass of a linear diorganopolysiloxane whose molecular chain ends are blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups, (D) a hydrolyzable organosilane compound having three or more silicon-bonded hydrolyzable groups in the molecule and / or a partial hydrolysis condensate thereof: 0.1 to 40 parts by mass, (E) curing catalyst: 0.001 to 20 parts by mass, and (F) Silane coupling agent: 0.05 to 20 parts by mass.

11. An easily dismantlable addition reaction curing liquid silicone adhesive used in the method for dismantling joined members according to any one of claims 1 to 7, comprising the following components (A), (B), and (G) to (I): (A) carbon nanotubes having an average diameter of 0.5 to 50 nm: 0.05 to 3.0% by mass of the total adhesive; (B) a hydroxide compound having a decomposition temperature of 180 to 600°C: 35 to 65% by mass of the total adhesive; (G) alkenyl group-containing organopolysiloxane having an alkenyl group bonded to a silicon atom at a molecular chain terminal: 100 parts by mass, (H) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, in an amount such that 0.01 to 3 moles of silicon-bonded hydrogen atoms are present per mole of silicon-bonded alkenyl groups in component (G); and (I) Platinum group metal catalyst: 0.01 to 1,000 ppm by mass of platinum group metal atoms relative to the total amount of components (G) and (H).

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