Method for dismantling joined members, joined members, and easily dismantled liquid silicone adhesive

Abstract

With regard to a bonded member in which a plurality of members are bonded together by a cured product obtained by curing a curable silicone-based liquid adhesive containing a hydroxide compound with a decomposition temperature of 180ºC-600ºC and a specific amount of particles which generate heat by means of microwaves, a dismantling method for the bonded member including a step in which the plurality of members are separated from each other by irradiating the cured product with microwaves and the bonded member is dismantled makes it possible to easily recycle the members because even though the cured product of the curable silicone-based liquid adhesive exhibits adhesiveness and / or sealing properties from room temperature to a high temperature of approximately 150ºC, the adhesiveness and / or sealing properties of the cured product of the curable silicone-based liquid adhesive are reduced by irradiating with microwaves, the plurality of members are easily separated from each other in a short time with little energy consumption, and it is thus possible to dismantle the bonded member.

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 and rapid collection, repair, and recycling of automobile parts such as automobile electrical components, electrical and electronic products, etc.; to bonded members that can be used in this method; and to an easily dismantled liquid silicone adhesive. [Background technology]

[0002] In recent years, recyclability has become increasingly important in a variety of fields due to its environmental friendliness and ability to reduce costs. For recycling purposes, it is necessary to disassemble bonded components into separate parts, even in the automotive, electrical, and electronics industries. However, since bonded components play an important role in preventing the intrusion of external dust and moisture and protecting internal components, they also require reliable sealing performance. Since adhesive sealing provides the best sealing performance, adhesiveness must be maintained even under a variety of 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 bonded components.

[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] Therefore, there is a demand for recyclable bonding members and methods for dismantling them, even in applications where silicone adhesives are used for bonding. [Prior art documents] [Patent documents]

[0007] [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] Patent application No. 2021-090750 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and aims to provide a joined member in which the joined adhesive members are a silicone-based adhesive, which maintains sealing performance at room temperature (23°C±15°C, the same applies hereinafter) and even after exposure to high temperatures of around 150°C, and which can be easily recycled in a short time with little energy consumption; a method for dismantling such a joined member; and an easily dismantled liquid silicone-based adhesive to be used in such a joined member. [Means for solving the problem]

[0009] To achieve the above object, the present inventors proposed a method in their previously filed Japanese Patent Application No. 2021-090750 (Patent Document 5) in which a specific proportion of aluminum hydroxide, which decomposes at around 160°C, is blended into a curable liquid silicone adhesive, allowing joined adhesive members to maintain their sealing properties even after being exposed to room temperature and even high temperatures of around 150°C, while exposing them to high temperatures of 160°C or higher to reduce their sealing properties and facilitate separation of the members. However, this method requires heating for long periods of time, lasting several hours, using a heating furnace, and therefore consumes a lot of energy.

[0010] Therefore, the present inventors have conducted extensive research into joining members that consume less energy and can be recycled in a shorter time, and methods for dismantling such members. As a result, in order to improve the efficiency and energy conservation of the recovery, repair, and recycling of electrical and electronic products, etc., a specific content of particles that generate heat in microwaves is added 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, and joining members (particularly made of organic resin and / or metal, etc.) joined with a cured product obtained by curing the curable liquid silicone adhesive are obtained. The inventors have discovered that a bonding member in which multiple (particularly two) components are bonded together (a bonded member in which the bonded adhesive member (a cured product of a curable liquid silicone adhesive) maintains its sealing properties even after being exposed to room temperature and even to a high temperature of around 150°C, but that its adhesiveness decreases when exposed to microwaves. It has also been discovered that by irradiating the adhesive member (a cured product of a curable liquid silicone adhesive) with microwaves, multiple (particularly two) components made of organic resin and / or metal can be separated, and the bonded member can be easily dismantled in a short time with little energy consumption, allowing 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] At least one type of particle selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, with a dielectric constant of 3 to 1,000 at 3 GHzA method for dismantling 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 particles that generate heat when exposed to microwaves and a hydroxide compound having a decomposition temperature of 180 to 600°C, wherein the content of the particles that generate heat when exposed to microwaves is 0.5 to 50 mass %, the method comprising the step of irradiating the cured product with microwaves to separate the plurality of components and dismantle 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] Microwave-heated particles Average particle size but, 0.05 to 100 μm The method for dismantling joined members according to [1] or [2]. [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 wavelength of the microwaves is 300 MHz or more and 300 GHz or less. [6] The method for dismantling bonded members according to any one of [1] to [5], 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. [7] The method for dismantling bonded members according to any one of [1] to [6], 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. [8] The method for dismantling joined members according to any one of [1] to [7], wherein the joined members are automobile parts or electric / electronic parts. [9] A bonded member used in the method for dismantling bonded members according to any one of [1] to [8].

[10] An easily dismantlable condensation-curable liquid silicone adhesive used in the method for dismantling bonded members according to any one of [1] to [8], comprising the following components (A) to (F): (A) At least one type of particle selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, with a dielectric constant of 3 to 1,000 at 3 GHz Microwave-generating particles: 0.5 to 50% by mass of the 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 [8], which contains the following components (A), (B) and (G) to (I): (A) At least one type of particle selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, with a dielectric constant of 3 to 1,000 at 3 GHz Microwave-generating particles: 0.5 to 50% by mass of the 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 a 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 to a bonded member in which multiple components are bonded together with a cured product obtained by curing a curable liquid silicone adhesive containing particles that generate heat when exposed to microwaves and a hydroxide compound having a decomposition temperature of 180 to 600°C, and in which the content of the microwave-generated particles is 0.5 to 50 mass %, thereby separating the multiple components, particularly components made of organic resin and / or metal, and dismantling the bonded member.

[0014] [Curable liquid silicone adhesive] The curable liquid silicone adhesive used in the present invention cures to form an adhesive member that bonds multiple components, particularly components made of organic resin and / or metal, and contains microwave-activated particles (A) and a hydroxide compound (B) having a decomposition temperature of 180 to 600°C, with the content of microwave-activated particles (A) being 0.5 to 50 mass%. The adhesive uses a polymer whose main chain comprises siloxane bonds as the base polymer, and the curing type is preferably a condensation curing type or an addition reaction curing type.

[0015] [Microwave-generated particles] The microwave-activated particles (A) used in the present invention generate heat when irradiated with microwaves, which causes the hydroxide compound (particularly a metal hydroxide or a hydroxide of a metal oxide) incorporated into the curable liquid silicone adhesive to decompose. The decomposition of the hydroxide compound generates water, which causes the adhesive to foam and reduce its adhesive strength, making it possible to easily dismantle the joined members in a short time with little energy consumption.

[0016] The particles have the property of generating heat when exposed to microwaves in order to provide dismantling properties. Any particles with such properties are preferred. ratio Particles with a high dielectric constant are more preferable because they have a high microwave absorption rate and generate heat efficiently in a short time. ratio The dielectric constant is preferably 3 to 1,000 at 3 GHz, and more preferably 5 to 800.

[0017] The particles that generate heat when exposed to microwaves are inorganic and are preferably at least one selected from the group consisting of carbon such as acetylene black, furnace black, channel black, thermal black, and Ketjen black; iron oxides such as iron (II) oxide, iron (III) oxide, and triiron tetroxide; titanium oxide compounds such as titanium oxide (TiO), titanium dioxide (TiO2), and dititanium trioxide (Ti2O3); ferrites such as spinel ferrite, magnetoplumbite ferrite, and garnet ferrite; and silicon carbide, of which acetylene black, titanium dioxide, and silicon carbide are more preferred.

[0018] The particles that generate heat when exposed to microwaves preferably have an average particle size of 0.05 to 100 μm, more preferably 0.1 to 80 μm. If the average particle size is smaller than 0.05 μm, the viscosity of the composition increases, making it impossible to achieve a high filling rate and resulting in insufficient heat generation. If the average particle size is larger than 100 μm, the flexibility of the rubber may be impaired. The average particle size can be determined as the cumulative weight average value D50 (or median diameter) using a particle size distribution analyzer using a laser diffraction method or the like.

[0019] The surfaces of the particles that generate heat when exposed to microwaves may be untreated or may be surface-treated (hydrophobized). When surface-treated, examples of the treating agent include alumina, silica, stearic acid, silane coupling agents, and silicone compounds. The surface treatment can be carried out by a known method. There are no particular restrictions on the amount of treatment, but it is preferably 10% by mass or less (usually 0.1 to 8% by mass), and particularly preferably 0.5 to 6% by mass.

[0020] The particles that generate heat when exposed to microwaves can be used alone or in combination of two or more.

[0021] The content of the particles that generate heat when exposed to microwaves is 0.5 to 50% by mass of the entire curable liquid silicone adhesive, preferably 1 to 40% by mass, more preferably 3 to 30% by mass, and even more preferably 5 to 20% by mass. If the content is less than 0.5% by mass, sufficient heat generation will not be achieved, and if the content exceeds 50% by mass, the viscosity of the composition will increase, making it difficult to mix and discharge during application.

[0022] [Hydroxylated compounds with decomposition temperatures of 180 to 600°C] The hydroxide compound (B) having a decomposition temperature of 180 to 600°C is usually preferably a metal hydroxide or a metal oxide hydroxide, and examples thereof include aluminum hydroxide having a decomposition temperature of around 180°C, magnesium hydroxide having a decomposition temperature of around 300°C, and aluminum oxide hydroxide (boehmite) having a decomposition temperature of around 500°C.

[0023] 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, thereby reducing the adhesive strength and making it easier to disassemble the joined components in a short period of time.

[0024] 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.

[0025] 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% by mass), particularly 0.2 to 2% by mass.

[0026] 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.

[0027] The content of the hydroxylated compound is 35 to 65 mass% of the total curable liquid silicone adhesive, preferably 40 to 60 mass%, and more preferably 45 to 55 mass%. If the content 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 the content is more than 65 mass%, the viscosity of the composition increases, making it difficult to mix and discharge during application. The total content of the microwave-generated particles (A) and the hydroxide compound (B) in the curable liquid silicone adhesive is preferably 36 to 85 mass%, more preferably 40 to 75 mass%, and even more preferably 45 to 65 mass%. The mass ratio of the microwave-generated particles (A) to the hydroxide compound (B) is preferably 1:0.8 to 1:50, more preferably 1:1 to 1:30, and even more preferably 1:2 to 1:20.

[0028] [Condensation-curing liquid silicone adhesive] Condensation-curing liquid silicone adhesives contain, in addition to the aforementioned (A) microwave-generated particles and (B) hydroxide compounds with a decomposition temperature of 180 to 600°C, (C) linear diorganopolysiloxanes (base polymers) with both molecular chain terminals blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups, (D) hydrolyzable organosilane compounds and / or their partial hydrolysis condensates (crosslinking agents) with three or more silicon-bonded hydrolyzable groups per molecule, (E) a curing catalyst, and (F) a silane coupling agent (adhesion-imparting agent), and are liquid silicone adhesives that obtain a cured product by utilizing a hydrolysis and condensation reaction caused by atmospheric moisture (humidity) at room temperature.

[0029] 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.

[0030] 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. 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 (i.e., alkoxysilyl groups) or alkoxy-substituted alkoxy groups (i.e., alkoxyalkoxysilyl groups) bonded to silicon atoms (i.e., present as dialkoxyorganosilyl groups or bis(alkoxyalkoxy)organosilyl groups, or trialkoxysilyl groups or tris(alkoxyalkoxy)silyl groups).

[0031] 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. 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 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) to form a crosslinked structure by hydrolysis and condensation reaction of the three or more hydrolyzable groups in the molecule with the linear diorganopolysiloxane base polymer, the molecular chain of which is terminally blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups.

[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 the silicon atom other than the hydrolyzable group. Examples of such an organic group bonded to the silicon atom other than the hydrolyzable group 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 as a crosslinking agent (curing agent) is clearly distinguishable from the silane coupling agent (F) as an adhesion promoter, which will be described later, in that the hydrolyzable organosilane compound does not have in its molecule a monovalent hydrocarbon group substituted with a functional group having a heteroatom such as a nitrogen atom, oxygen atom, or sulfur atom.

[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 is it uneconomical, but the elongation and durability of the cured product may be reduced.

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

[0050] 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 it exceeds 20 parts by mass, weather resistance and mechanical properties will be poor.

[0051] 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).

[0052] Specific examples of optional inorganic fillers 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, particulate 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 is added, the amount added is preferably 0.1 to 800 parts by mass, more preferably 0.5 to 600 parts by mass, per 100 parts by mass of the linear diorganopolysiloxane the molecular chain of which is terminally blocked with silicon-bonded hydroxyl groups and / or hydrolyzable silyl groups.

[0053] 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.

[0054] 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).

[0055] [Addition reaction curing liquid silicone adhesive] The addition reaction curing liquid silicone adhesive contains, in addition to the above-mentioned (A) microwave-activated particles 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 silicon-bonded hydrogen 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 produce a cured product.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] The alkenyl group-containing organopolysiloxane as the base polymer (main component) may be used either alone or in combination of two or more.

[0061] 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) in the molecule, and preferably has no aliphatic unsaturated bonds in the molecule.

[0062] 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.

[0063] Preferably, the number of silicon atoms in the molecule is 2 to 300, particularly 3 to 150, and particularly 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.

[0064] 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.

[0065] The organohydrogenpolysiloxanes may be used alone or in combination of two or more.

[0066] 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.

[0067] (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.

[0068] 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 0.1 to 1,000 ppm, preferably 1 to 300 ppm, calculated as the mass of platinum group metal atoms relative to the total amount of the alkenyl group-containing organopolysiloxane and organohydrogenpolysiloxane. If this amount is too high, the heat resistance of the resulting cured product may decrease.

[0069] 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.

[0070] 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.

[0071] 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, and if it exceeds 20 parts by mass, weather resistance and mechanical properties may be poor.

[0072] In addition to the above components, the addition reaction curable liquid silicone adhesive can contain optional components within the scope of the present invention. These optional components include, for example, a reaction inhibitor, the same inorganic fillers as those exemplified in the condensation curable liquid silicone adhesive described above (excluding the microwave-heat-generating particles of component (A) and the hydroxide compound of component (B) having a decomposition temperature of 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, thixotropy-imparting agents, pigments, dyes, etc.

[0073] 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. The curing conditions for the addition reaction curing liquid silicone adhesive may be 23 to 150°C, particularly 23 to 100°C, for 10 minutes to 8 hours, particularly 30 minutes to 5 hours.

[0074] [Connection material] In the method for dismantling bonded members of the present invention, the bonded members are formed by bonding together multiple (particularly two) identical or different members using a cured product (an adhesive member made of an adhesive silicone rubber cured product) obtained by curing a curable liquid silicone adhesive containing microwave-generated particles and a hydroxide compound having a decomposition temperature of 180 to 600°C. In the bonded member, 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 identical or different organic resin members, and combinations of metal members and organic resin members. Examples of organic resins constituting the organic resin members include polyamide resins such as PBT (polybutylene terephthalate resin), PPS (polyphenylene sulfide resin), PA66 (nylon 66), PA6 (nylon 6), and PC (polycarbonate resin), while examples of metals constituting the metal members include aluminum, iron, SUS, copper, etc. The organic resins or metals constituting the organic resin members or metal members preferably have a heat resistance temperature of 160°C or higher.

[0075] [Method of manufacturing joining members] A curable liquid silicone adhesive containing microwave-generating particles 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, allowing the components to cure by simply leaving them alone after joining. To accelerate the curing, humidification is effective. When the curable liquid silicone adhesive of the present invention is an addition-reaction-curing liquid silicone adhesive, it cures by addition reaction at temperatures of 23 to 150°C, allowing the components to cure by simply leaving them alone or heating after joining.

[0076] Examples of the joining member include automobile parts such as engines, transmissions, ECUs and PCUs, and electric / electronic parts such as smartphones, tablets, liquid crystal displays and batteries, and automobile parts and electric / electronic parts are preferred.

[0077] 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.

[0078] The above-mentioned joining members are preferably easily dismantled, being joined with a certain degree of adhesive strength during normal use, but decreasing in adhesive strength after heating to such an extent that the members can be separated. Specifically, the initial shear adhesive strength of the joining members is preferably 1.2 MPa or more, particularly 1.5 MPa or more, and the shear adhesive strength of the joining members after microwave irradiation is preferably 1 MPa or less. This shear adhesive strength is a value measured in accordance with the method specified in JIS K6850. The initial and post-heat shear adhesive strengths can be set within the above-mentioned ranges by adjusting the composition of the curable liquid silicone adhesive to fall within the specific ranges described above.

[0079] [Disassembly method] In the method for dismantling bonded members of the present invention, a cured product (cured adhesive silicone rubber product) obtained by curing a curable liquid silicone adhesive, which is the adhesive member of the bonded members, is irradiated with microwaves, and then cooled to room temperature. The bonded members can be dismantled by either allowing the components to peel off naturally, or by applying force by hand 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 be recycled.

[0080] 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 exposed to microwaves, the particles of component (A) generate heat. (2) The particles of component (A) generate heat, which 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 particles 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.

[0081] The microwaves to be irradiated preferably have a frequency, power, and duration that are such that the adhesive strength is reduced to such an extent that the components can be separated after irradiation. The frequency can be selected from the range of 300 MHz to 300 GHz, and the power can be selected from the range of 300 W to 5,000 W. The microwave irradiation duration is not particularly limited, but is 30 minutes or less, preferably 15 minutes or less, and more preferably 5 minutes or less. [Example]

[0082] 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, and the average particle size is the value determined as the cumulative weight average value D50 (or median size) using a particle size distribution measuring device using a laser light diffraction method. ratio The dielectric constant is shown as the value at 3 GHz.

[0083] Preparation of curable liquid silicone adhesive (composition) [Composition Example 1] The polymer contains 100 parts by mass of dimethylpolysiloxane with a viscosity of 30,000 mPa·s and both ends of the molecular chain blocked with trimethoxysilyl groups, and acetylene black powder ( ratioComposition 1 was obtained by uniformly mixing 12 parts by mass (amount in the entire composition: 5.1% by mass of the entire composition) of aluminum hydroxide having an average particle size of 10 μm and an untreated surface (amount in the entire composition: 50.6% by mass of the entire composition), 4 parts by mass of vinyltrimethoxysilane, 0.5 parts by mass of γ-aminopropyltriethoxysilane, 0.5 parts by mass of a compound obtained by dehydrochlorination of xylylenediamine and 3-chloropropyltrimethoxysilane, as shown in the following formula (1), and 0.1 parts by mass of dioctyltin dineodecanoate. [ka]

[0084] Composition Example 2 The polymer contains 100 parts by mass of dimethylpolysiloxane with a viscosity of 20,000 mPa·s and both ends of the molecular chain blocked with hydroxyl groups, and acetylene black powder ( ratio Composition 2 was obtained by uniformly mixing 12 parts by mass (amount in the entire composition: 5.0% by mass of the entire composition) of magnesium hydroxide having an average particle diameter of 1 μm and an untreated surface (amount in the entire composition: 50.2% by mass of the entire composition), 6 parts by mass of vinyltrimethoxysilane, 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 above formula (1), and 0.1 parts by mass of dioctyltin dineodecanoate.

[0085] Composition Example 3 The polymer consisted of 100 parts by mass of dimethylpolysiloxane with a viscosity of 20,000 mPa·s, both ends of which were blocked with hydroxyl groups, an average particle size of 0.3 μm, and titanium dioxide ( ratioComposition 3 was obtained by uniformly mixing 20 parts by mass (content in the entire composition: 8.1% by mass of the entire composition) of aluminum hydroxide having an average particle size of 10 μm and an untreated surface (content in the entire composition: 48.6% by mass of the entire composition), 5 parts by mass of phenyltriisopropenoxysilane, 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 above formula (1), and 0.7 parts by mass of tetramethylguanidylpropyltrimethoxysilane.

[0086] [Comparative Composition Example 1] Composition 4 was obtained by uniformly mixing 100 parts by mass of dimethylpolysiloxane whose molecular chain ends are blocked with trimethoxysilyl groups and whose viscosity is 30,000 mPa s, 12 parts by mass of fumed silica, 4 parts by mass of vinyltrimethoxysilane, 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 above formula (1), and 0.1 parts by mass of dioctyltin dineodecanoate.

[0087] [Comparative Composition Example 2] Composition 5 was obtained by uniformly mixing 100 parts by mass of dimethylpolysiloxane whose molecular chain ends were capped with trimethoxysilyl groups and had a viscosity of 30,000 mPa s, 120 parts by mass of aluminum hydroxide whose average particle size was 10 μm and whose surface was untreated (amount in the entire composition: 52.2% by mass), 5 parts by mass of fumed silica, 4 parts by mass of vinyltrimethoxysilane, 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 above formula (1), and 0.1 parts by mass of dioctyltin dineodecanoate.

[0088] [Comparative Composition Example 3] The polymer contains 100 parts by mass of dimethylpolysiloxane with a viscosity of 30,000 mPa·s and both ends of the molecular chain blocked with trimethoxysilyl groups, and acetylene black powder ( ratio Composition 6 was obtained by uniformly mixing 0.3 parts by mass (0.1% by mass of the entire composition) of aluminum hydroxide having a dielectric constant of 37, 120 parts by mass (53.2% by mass of the entire composition) of untreated surface and an average particle size of 10 μm, 4 parts by mass of vinyltrimethoxysilane, 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 above formula (1), and 0.1 parts by mass of dioctyltin dineodecanoate.

[0089] [Production of joining members] Two PBT (polybutylene terephthalate resin, heat resistance temperature: 150°C or higher) substrates, each 25 mm wide and 100 mm long, were used as the substrates, and one of the above compositions 1 to 6 was used as the curable liquid silicone adhesive. The two PBT substrates were bonded together to a bonded thickness of 0.5 mm and a bonded area of ​​2.5 cm2, and then cured at 23°C / 50% RH for 7 days to produce a bonded member in which the two PBT substrates were bonded together with the cured product of the curable liquid silicone adhesive (cured adhesive silicone rubber).

[0090] Disassembly evaluation [Examples 1 to 3, Comparative Examples 1 to 3] The adhesive strength (dismantleability) of the bonded members prepared above was evaluated by the following evaluation method. The results are shown in Table 1.

[0091] (1) Adhesive strength (initial) Using the bonded members prepared above, the shear adhesive strength (initial) was measured in accordance with the method specified in JIS K6850.

[0092] (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 for the time indicated in the table, 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). Note that if the substrates were decomposed after microwave irradiation but before the shear adhesive strength measurement, the composition was deemed to have peeled.

[0093] [Table 1]

[0094] As is clear from the above results, the adhesive strength of the cured product of the curable liquid silicone adhesive used in the method for dismantling bonded members of the present invention decreases when microwaves are irradiated, due to the decomposition of the hydroxide compound. As a result, bonded resin members bonded with the cured product of the curable liquid silicone adhesive (cured adhesive silicone rubber) can be easily dismantled in a short time of 90 to 180 seconds with little energy consumption. On the other hand, in Comparative Examples 1 and 2, the absence of heat-generating particles even when microwaves were applied meant that dismantling was not possible. That is, even when microwaves were applied, the adhesive strength of the cured adhesive silicone rubber (adhesive member) remained almost unchanged, and heat resistance (adhesiveness) was maintained, so the bonded members could not be dismantled. In addition, in Comparative Example 3, particles that generate heat when exposed to microwaves are present, but the content is small and below the specified amount, so a sufficient heat-generating effect is not obtained, the adhesive strength is not reduced sufficiently, and dismantling ability is not achieved.

Claims

1. A method for dismantling a joined member in which multiple members are joined together with a cured product obtained by curing a curable liquid silicone adhesive containing 0.5 to 50 mass % of microwave-activated particles that generate heat when exposed to microwaves, the cured product being at least one type of particle selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, each having a dielectric constant of 3 to 1,000 at 3 GHz, and a hydroxide compound having a decomposition temperature of 180 to 600°C, the method comprising the steps of irradiating microwaves to the cured product to separate the multiple members and dismantle the joined 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 particles that generate heat when exposed to microwaves have an average particle size of 0.05 to 100 μm.

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 wavelength of the microwaves is 300 MHz or more and 300 GHz or less.

6. 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.

7. 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.

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

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

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 8, comprising the following components (A) to (F): (A) microwave-generating particles, which are at least one type of particles selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, and have a dielectric constant of 3 to 1,000 at 3 GHz: 0.5 to 50% 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 8, comprising the following components (A), (B), and (G) to (I): (A) microwave-generating particles, which are at least one type of particles selected from carbon, iron oxide, titanium oxide-based compounds, ferrite, and silicon carbide, and have a dielectric constant of 3 to 1,000 at 3 GHz: 0.5 to 50% 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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