Resin composite, method for manufacturing resin composite, and method for dismantling resin composite

Abstract

To provide a resin composite which combines high adhesion strength and high recyclability, a method for producing the resin composite, and a method for disassembling the resin composite.SOLUTION: A resin composite 101 comprises a first resin member 1 having a dynamic covalent bond capable of reversibly dissociating or bonding, and a second resin member 2 which is a different resin than the first resin member 1 and has, at least on the surface thereof, a target functional group capable of bonding with the dynamic covalent bond. The first resin member 1 and the second resin member 2 are joined by covalent bonding through the dynamic covalent bond and the target functional group. The resin composite 101 can be produced by bringing the first resin member 1 and the second resin member 2 into contact, and heating at least the contact portion. The resin composite 101 can be disassembled by heating the portion of the covalent bond.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a resin composite, a method for manufacturing a resin composite, and a method for dismantling a resin composite. [Background technology]

[0002] In order to impart multiple functions, multiple resin components may be used in combination. For example, in response to environmental regulations and energy conservation, efforts are being made to reduce the weight of moving bodies such as automobiles, aircraft, and railway vehicles, and components may be made from resin components containing, for example, fibers, fillers, etc. One known technology related to resin composites is described in Patent Document 1. The abstract of Patent Document 1 states that "a core material is made up of multiple foamed bead molded bodies, and the core material is formed from foamed bead molded bodies in which the air bubbles inside the beads near the bonding surfaces are flattened." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-163733 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, resin components are bonded together using an adhesive to improve adhesive strength (paragraph 0014). Here, it is preferable to recycle resin components that make up a resin composite that is no longer needed, such as defective products generated during the production of the resin composite or resin composites after use. However, in the technology described in Patent Document 1, the use of an adhesive makes it difficult for the resin components to be separated from each other, making it difficult to recycle the resin components. The present disclosure provides a resin composite that combines high adhesive strength and high recyclability, a method for manufacturing a resin composite, and a method for dismantling a resin composite. [Means for solving the problem]

[0005] The resin composite of the present disclosure comprises a first resin member having a dynamic covalent bond that can be reversibly dissociated or bonded, and a second resin member that is a resin different from the first resin member and has a target functional group that can bond with the dynamic covalent bond at least on its surface, and the first resin member and the second resin member are bonded together by a covalent bond mediated by the dynamic covalent bond and the target functional group. The second resin member includes a second resin that is a urethane having a hydroxyl group as the target functional group. Other solutions will be described later in the detailed description of the invention. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to provide a resin composite that achieves both high adhesive strength and high recyclability, a method for manufacturing a resin composite, and a method for dismantling a resin composite. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a resin composite of the present disclosure. [Figure 2] FIG. 10 is a diagram illustrating a dynamic covalent bond formed between a first functional group and a target functional group, showing the state when a first resin member and a second resin member are bonded together. [Figure 3] 1A to 1C are diagrams illustrating a method for producing a resin composite according to the present disclosure. [Figure 4] 3A and 3B are diagrams illustrating the surface structures of a first resin member and a second resin member. [Figure 5] 1A to 1C are diagrams illustrating a method for dismantling a resin composite according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, modes for carrying out the present disclosure (hereinafter referred to as "embodiments") will be described with reference to the drawings. In the following description of one embodiment, other embodiments applicable to the one embodiment will also be described as appropriate. The present disclosure is not limited to the one embodiment below, and different embodiments can be combined with each other or modified as desired without significantly impairing the effects of the present disclosure. Furthermore, the same components will be given the same reference numerals, and redundant descriptions will be omitted. Furthermore, components having the same functions will be given the same names. The contents shown are merely schematic, and for convenience of illustration, changes may be made from the actual configuration within the scope of not significantly impairing the effects of the present disclosure, and some components may be omitted or modified between drawings.

[0009] FIG. 1 is a cross-sectional view of a resin composite 101 according to the present disclosure. The resin composite 101 comprises a first resin member 1 and a second resin member. The first resin member 1 has a dynamic covalent bond that can reversibly dissociate or bond. The second resin member 2 is a resin different from the first resin member 1, and has, at least on its surface, a target functional group that can bond with the dynamic covalent bond of the first resin member 1. Here, "different" means that at least one of the structure (such as the type of unit monomer) or physical property (such as molecular weight) is different.

[0010] 2 is a diagram illustrating the dynamic covalent bond formed between the first functional group and the target functional group, and illustrates bonding between the first resin member 1 and the second resin member 2. The first resin member 1 and the second resin member 2 are bonded together by the dynamic covalent bond of the first resin member 1 and the covalent bond mediated by the target functional group of the second resin member 2.

[0011] In the illustrated example, the dynamic covalent bond is, for example, an ester bond, and the target functional group is, for example, a hydroxyl group, but neither is limited thereto. The ester bond is formed, for example, by dehydration condensation between a carboxylic acid or carboxylic anhydride constituting the first resin member 1 and a hydroxyl group. The dynamic covalent bond will be described with reference to formula (1).

[0012]

number

[0013] Formula (1) is a chemical reaction formula that explains the dissociation and bonding of dynamic covalent bonds, and represents a transesterification reaction. The chemical formula shown in formula (1) is a part of the structure obtained by the transesterification reaction. R and R'' are organic groups derived from the first resin member 1, and R' is an organic group derived from the second resin member 2. For example, the first resin member 1 and the second resin member 2 are joined together by forming a dynamic covalent bond through bonding between functional groups present on the surfaces.

[0014] Meanwhile, in the state shown on the left side, heating at least the bonded portion recombines the dynamic covalent bonds, and the reaction proceeds to the right side. As a result, a dynamic covalent bond is formed between RO of the first resin member 1 and R″OH of the second resin member 2, resulting in the first resin member 1 shown in the first item on the right side and the second resin member 2 shown in the second item on the right side. As a result, the ester bond formed between the first resin member 1 and the second resin member 2 is easily cleaved at part A, causing the dynamic covalent bond to recombine and the bond to be released.

[0015] The first resin member 1 is not particularly limited as long as it is a resin having a dynamic covalent bond, and examples thereof include at least one of epoxy resin, phenol resin, polyester resin, and the like.

[0016] In particular, the first resin member 1 preferably contains a first resin that is an epoxy resin. By containing an epoxy resin, the composition ratio of the epoxy monomer and the acid anhydride curing agent can be adjusted, and ester groups and hydroxyl groups, which are dynamic covalent bonds, can be easily introduced by a curing reaction. Below, an example will be given in which the first resin is an epoxy resin, but the first resin is not limited to an epoxy resin.

[0017] The epoxy resin can be obtained by curing a mixture containing, for example, an epoxy compound having two or more epoxy groups in the molecule, at least one curing agent selected from carboxylic acids or carboxylic anhydrides, and a transesterification catalyst that promotes the transesterification reaction. The mixture may further contain a polymerization initiation catalyst, etc.

[0018] For example, in the presence of a curing accelerator (described below), an epoxy compound reacts with a curing agent during curing, resulting in the formation of ester bonds (ester groups) and hydroxyl groups. These ester bonds and hydroxyl groups then initiate a transesterification reaction when heated in the presence of a transesterification catalyst. By setting the amounts of the ester bonds, hydroxyl groups, and transesterification catalyst within predetermined ranges and heating at an appropriate temperature, the transesterification reaction continues even after curing, resulting in a resin composite 101 with high bonding strength and easy peeling.

[0019] Examples of epoxy compounds having two or more epoxy groups in the molecule include bisphenol A resins, novolac resins, alicyclic resins, and glycidylamine resins. Examples of epoxy compounds include at least one of bisphenol A diglycidyl ether phenol, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, resorcinol diglycidyl ether, hexahydrobisphenol A diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, phthalic acid diglycidyl ester, dimer acid diglycidyl ester, triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane, tetraglycidyl metaxylenediamine, cresol novolac polyglycidyl ether, tetrabromobisphenol A diglycidyl ether, and bisphenol hexafluoroacetone diglycidyl ether, but are not limited thereto.

[0020] Examples of carboxylic acids and acid anhydrides that serve as curing agents include at least one of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 3-dodecenylsuccinic anhydride, octenylsuccinic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, dodecylsuccinic anhydride, chlorendic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, ethylene glycol bis(anhydrotrimate), methylcyclohexenetetracarboxylic anhydride, trimellitic anhydride, polyazelaic anhydride, ethylene glycol bisanhydrotrimellitate, 1,2,3,4-butanetetracarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and polyvalent fatty acids, but are not limited to these.

[0021] The amount of acid anhydride added is, for example, 30 mol% or more and 70 mol% or less relative to the epoxy groups. It is more desirable to use 40 mol% or more and 60 mol% or less. By using an amount of acid anhydride within this range, hydroxyl groups remain after polymerization, allowing for efficient reorganization of the polymer structure through dynamic covalent bonds. In particular, using an amount of acid anhydride of 30 mol% or more allows for sufficient curing. Using an amount of acid anhydride of 70 mol% or less increases the amount of hydroxyl groups produced, facilitating the progress of the transesterification reaction.

[0022] The first resin member 1 may contain a vinyl monomer having a hydroxyl group, an ester group, and two or more vinyl groups, and a polymerization initiator for polymerizing the vinyl monomer. Specific examples of the vinyl monomer include 2-hydroxymethacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, divinylethylene glycol, monomethyl fumarate, hydroxypropyl acrylate, ethyl 2-(hydroxymethyl)acrylate, glycerol dimethacrylate, allyl acrylate, methyl crotonate, methyl methacrylate, methyl 3,3-dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, dimethyl fumarate, fumaric acid, 1, Examples of the methacrylate include at least one of 4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,3-butanediol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, vinyl crotonate, crotonic anhydride, diallyl maleate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, bisphenol A glycerolate dimethacrylate, and the like, but are not limited to these.

[0023] Examples of the polymerization initiator catalyst include peroxide polymerization initiators and azo compound polymerization initiators. Specific examples include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 1,1'-azobis(cyclohexanecarbonitrile), and 2,2'-azobis(2,4,4-trimethylpentane); dialkyl peroxides such as di-t-butyl peroxide, di-t-hexyl peroxide, and dicumyl peroxide; 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 2,2-bis(4,4-di-t-butylperoxide); peroxyketals such as t-butyl peroxybenzoate, t-hexyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxylaurate, t-hexyl peroxyneodecanoate, peroxyesters such as benzoyl peroxide, lauroyl peroxide, and peroxycarbonates such as t-butyl peroxyisopropyl monocarbonate, t-hexyl peroxyisopropyl monocarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate, but are not limited to these.

[0024] The transesterification catalyst is preferably one that disperses uniformly in the mixture and promotes the transesterification reaction. For example, manganese(III) acetylacetonate, zinc(II) acetate, zinc(II) acetylacetonate, zinc naphthenate(II), iron(III) acetylacetonate, cobalt(II) acetylacetonate, cobalt(III) acetylacetonate, aluminum isopropoxide, titanium isopropoxide, methoxide(triphenylphosphine) copper(I) complex, ethoxide(triphenylphosphine) copper(I) complex, propoxide(triphenylphosphine) copper(I) complex, isopropoxide(triphenylphosphine) copper(I) complex, methoxidebis(triphenylphosphine) copper(II) complex, ethoxidebis(triphenylphosphine) copper(II) complex, propoxidebis( Examples of the oxidizing agent include, but are not limited to, at least one of bis(triphenylphosphine)copper(II) complex, isopropoxidebis(triphenylphosphine)copper(II) complex, tris(2,4-pentanedionato)cobalt(III), cobalt(II) naphthenate, cobalt(II) stearate, tin(II) diacetate, tin(II) di(2-ethylhexanoate), N,N-dimethyl-4-aminopyridine, diazabicycloundecene, diazabicyclononene, triazabicyclodecene, triphenylphosphine, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazole.

[0025] The first resin member 1 preferably contains at least one type of fiber. The inclusion of fiber can improve the strength of the first resin member 1 and can improve the strength and rigidity of the entire resin composite 101 including the second resin member 2 covalently bonded to the first resin member 1.

[0026] Examples of fibers include inorganic fibers and organic fibers. Examples of inorganic fibers include aramid fibers, glass fibers, asbestos fibers, carbon fibers, silica fibers, silica-alumina fibers, alumina fibers, zirconia fibers, potassium titanate fibers, Tyranno fibers, silicon carbide fibers, and metal fibers. Examples of organic fibers include high-strength polyethylene fibers, polyacetal fibers, aliphatic or aromatic polyamide fibers, polyacrylate fibers, fluorine fibers, boron fibers, polyacrylonitrile fibers, aramid fibers, and PBO (poly-p-phenylene benzobisoxazole) fibers. These fibers can be used alone or in combination.

[0027] Among these fibers, organic fibers, particularly carbon fibers, are preferred in terms of mechanical strength and the like. Carbon fibers can be classified into synthetic polymer-derived carbon fibers (such as polyacrylonitrile-based, polyvinyl alcohol-based, and rayon-based carbon fibers) and mineral-derived carbon fibers (such as pitch-based carbon fibers) depending on their raw materials. Of these, synthetic polymer-derived carbon fibers are preferred in terms of mechanical strength. These fibers are used in the form of continuous fibers, long fibers, short fibers, chopped fibers, and the like, and in the form of unidirectional materials, plain weaves, nonwoven fabrics, and the like. They may also be added directly to the first resin member 1, but the present embodiment is not limited to these fiber shapes and fiber states.

[0028] The method for producing the first resin member 1 containing fibers is not particularly limited, and examples thereof include a method of stacking fibers impregnated with the first resin and then pressurizing and heating them, a method of injecting the first resin into a mold on which fibers are laid and then heating them, and a method of kneading fibers into the first resin and then injection molding them.

[0029] The first resin member 1 may contain at least one type of inorganic filler. Examples of inorganic fillers include powders such as fused silica, crystalline silica, alumina, zircon, calcium silicate, calcium carbonate, potassium titanate, silicon carbide, aluminum nitride, boron nitride, beryllia, zircon, fosterite, stearite, spirel, mullite, and titania, as well as spherical beads and glass fibers formed from these. There are no limitations on the shape of the inorganic filler, and it may be spherical, flaky, or the like.

[0030] The first resin member 1 may contain at least one additive, such as a curing accelerator, a flame retardant, an antioxidant, a light stabilizer, a dispersant, a lubricant, a plasticizer, an antistatic agent, a pigment, or a dye, as needed.

[0031] As described above, the second resin member 2 has target functional groups capable of dynamic covalent bonding at least on its surface. There are no particular limitations on the method for forming the target functional groups on the surface of the second resin member 2, but for example, the target functional groups can be arranged by surface modification of the surface of the second resin member 2. The surface modification can be carried out, for example, by oxidation.

[0032] It is preferable that the second resin member 2 also has the target functional group inside. This allows the second resin member 2 to be easily formed by, for example, molding a resin having the target functional group. The second resin member 2 can be formed by, for example, including at least one of urethane, epoxy resin, phenol resin, polyvinyl alcohol resin, and the like.

[0033] In particular, the second resin member 2 preferably contains a second resin that is urethane having a hydroxyl group as the target functional group. By including a second resin that is urethane, the following effects can be obtained, for example: When a conventional adhesive is used to bond urethane, the urethane impregnates the adhesive, which increases the amount of adhesive used and tends to make the resin composite 101 heavier. However, in the present disclosure, no adhesive is used, or only a small amount is used, so the resin composite 101 can be made lighter even when bonding urethane. The urethane may be foamed (urethane foam) or unfoamed. Below, an example will be given in which the second resin is urethane, but the second resin is not limited to urethane.

[0034] Urethane can be obtained, for example, by polymerizing polyol and polyisocyanate. These are mixed in a predetermined ratio and cured by heating to obtain a desired shape.

[0035] The specific type of polyol is not particularly limited. Examples include at least one of polyester polyol, polyether polyol, acrylic polyol, and low-molecular-weight polyol. Examples of polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyethylene butylene adipate diol, polyhexamethylene isophthalate adipate diol, polyethylene succinate diol, polybutylene succinate diol, polyethylene sebacate diol, polybutylene sebacate diol, poly-ε-caprolactone diol, poly(3-methyl-1,5-pentylene adipate) diol, and polycondensates of 1,6-hexanediol and dimer acid. Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random or block copolymers of ethylene oxide and propylene oxide, and random or block copolymers of ethylene oxide and butylene oxide. Furthermore, polyether polyester polyols having ether bonds and ester bonds can also be used. The low-molecular-weight polyol is not particularly limited, and examples thereof include ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanediol. Furthermore, low-molecular-weight polyhydric alcohols such as trimethylolpropane, pentaerythritol, and sorbitol can also be used. These can be used alone or in combination of two or more.

[0036] The specific type of polyisocyanate is not particularly limited. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, Examples of suitable organic diisocyanates include aromatic diisocyanates such as isocyanates, aromatic polyisocyanates such as polyphenylene polymethylene polyisocyanate and crude tolylene diisocyanate, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate and lysine diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate and tetramethyl xylene diisocyanate, as well as biuret-modified, uretdione-modified, carbodiimide-modified, isocyanurate-modified and uretonimine-modified organic polyisocyanates, and mixed modified products thereof. These may be used alone or in combination of two or more.

[0037] Other than the above, the same features as those of the first resin member 1 can be applied to the second resin member 2 as needed.

[0038] 3 is a diagram illustrating a method for producing a resin composite 101 according to the present disclosure. The resin composite 101 can be produced by bringing a first resin member 1 having a dynamic covalent bond into contact with a second resin member 2, which is a different resin from the first resin member 1 and has a target functional group, and then heating at least the contacting portion. Upon heating, the first resin member 1 and the second resin member 2 are bonded together by a covalent bond mediated by the dynamic covalent bond and the target functional group. In the illustrated example, the first resin member 1 and the second resin member 2 are flat, but their shapes are not limited to flat plates.

[0039] FIG. 4 is a diagram illustrating the surface structures of the first resin member 1 and the second resin member 2. The surface of the first resin member 1 contains multiple dynamic covalent bonds, such as ester bonds. Meanwhile, the surface of the second resin member 2 contains multiple target functional groups, such as hydroxyl groups. When the first resin member and the second resin member are brought into contact (e.g., superimposed) and at least the contact area (or the entire surface) is heated, the ester bonds are broken, generating carbonyl groups with unpaired electrons. The generated carbonyl groups are highly reactive and easily bond with hydroxyl groups present on the surface of the second resin member 2, generating new ester bonds between the first resin member 1 and the second resin member 2. The generated ester bonds are dynamic covalent bonds that can be broken by further heating, as shown in FIG. 2 above. These reactions bond the first resin member 1 and the second resin member 2 together via covalent bonds, improving the bonding strength between the first resin member 1 and the second resin member 2.

[0040] Heating can be performed by any method. For example, the entire structure may be heated in a thermostatic chamber or the like, or a desired position may be heated by irradiating it with microwaves or infrared rays. Furthermore, heating may be performed by, for example, pressing a heated metal plate using an electric heater or the like against a desired position. Heating may be performed while pressing (applying a pressing force) the first resin member 1 and the second resin member 2 in the contact direction (for example, the stacking direction), or without pressing. When heating without pressing, pressing may be performed, for example, after heating and before cooling.

[0041] The heating temperature varies depending on the material composition and compounding ratio of the first resin member 1 and the second resin member 2, but can be, for example, above the glass transition temperature (the temperature at which recombination of dynamic covalent bonds occurs) of each of the first resin and the second resin, and below the temperature at which each of the first resin and the second resin does not thermally decompose. Specifically, for example, when the first resin is an epoxy resin and the second resin is a urethane, the heating temperature can be, for example, above 100°C, preferably above 150°C, with the upper limit being, for example, below 300°C, preferably below 200°C. The heating time can be, for example, from 1 hour to 10 hours. The heating temperature and heating time may be the same or different when joining the first resin member 1 and the second resin member 2 and when separating them.

[0042] 5 is a diagram illustrating a method for dismantling a resin composite 101 according to the present disclosure. At least the dynamic covalent bond and the covalent bond via the target functional group in the resin composite 101 are heated to dissociate the target functional group from the dynamic covalent bond, and the resin composite 101 is dismantled into a first resin member 1 and a second resin member 2. This facilitates dismantling and improves recyclability.

[0043] Heating can be performed under the same conditions as those for bonding described with reference to Fig. 4. For example, heating may be performed while applying a pulling force in the contact direction (e.g., the stacking direction) between the first resin member 1 and the second resin member 2, or heating may be performed without applying such a force. Furthermore, when heating is performed without applying such a force, they can be separated by applying a pulling force after heating. [Example]

[0044] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0045] Example 1 The first resin member 1 (Figure 1) was prepared as follows. First, 100 parts by weight of a bisphenol A diglycidyl ether epoxy compound (jER828, manufactured by Mitsubishi Chemical Corporation) was mixed with 47 parts by weight of an acid anhydride (MHAC-P, manufactured by Showa Denko Materials Co., Ltd.), 19 parts by weight of manganese(III) acetylacetonate (a transesterification catalyst, manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.3 parts by weight of 2E4MZ-CN (manufactured by Shikoku Chemical Industry Co., Ltd.) as a curing accelerator. The mixture was stirred and mixed in air to obtain a mixture. The amount of acid anhydride used was 50 mol% (half the amount in stoichiometric ratio) of the epoxy compound used, and the amount of manganese(III) acetylacetonate used was 10 mol% of the epoxy compound used. Next, the mixture was heated at 100°C for 1 hour and then at 200°C for 1 hour to cure the mixture and obtain a flat-plate-shaped first resin member 1. The first resin member 1 has, on its surface and inside, ester bonds formed by dehydration condensation between acid anhydride and hydroxyl groups as dynamic covalent bonds.

[0046] The second resin member 2 (FIG. 1) was produced as follows. First, 7 parts by mass of polyol (NIPPOLAN 982R, manufactured by Nippon Polyurethane Co., Ltd.), 16 parts by mass of polyisocyanate (CORONATE HXR, manufactured by Nippon Polyurethane Co., Ltd.), and 3 parts by mass of amine (Polycat 8, manufactured by San-Apro Co., Ltd.) were mixed to obtain a mixture. Next, the mixture was heated at 80°C for 1 hour to obtain a flat plate-shaped second resin member 2. The second resin member 2 is a different resin from the first resin member 1, and has hydroxyl groups as target functional groups on its surface and inside.

[0047] A resin composite 101 (Fig. 1) was obtained by stacking a flat plate-shaped first resin member 1 and a flat plate-shaped second resin member, hot pressing them at 190°C for 1 hour, and then cooling them to room temperature. An attempt was made to separate the first resin member 1 and the second resin member 2 by holding them with one hand and the other hand. However, even when pulling with both hands, they did not separate, confirming that they were firmly bonded. This is thought to be because the first resin member 1 and the second resin member 2 were bonded by a dynamic covalent bond.

[0048] Next, the resin composite 101 was placed in a thermostatic chamber and heated in air at 200°C for 1 hour. Immediately after heating for 1 hour, an attempt was made to peel the composite by pulling with both hands while wearing gloves, and the composite was successfully peeled off with only a slight force. This confirmed that the resin composite 101 could be easily disassembled by heating. This is thought to be because the dynamic covalent bonds were recombined by heating, and the dynamic covalent bonds formed between the first resin member 1 and the second resin member 2 were broken.

[0049] <Example 2> A resin composite 101 (FIG. 1) was fabricated in the same manner as in Example 1, except that a polyester resin (having a dynamic covalent bond) was used instead of an epoxy resin for the first resin member 1 (FIG. 1). When peeling was attempted in the same manner as in Example 1, peeling was not possible before heating, but peeling was easily achieved immediately after heating. These results confirmed high bonding strength and high recyclability. The polyester resin was prepared by curing a vinyl monomer containing an ester group and a hydroxyl group with a reaction initiator. The polyester resin was obtained by stirring 100 parts by weight of styrene (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 parts by weight of bisphenol A glycerolate dimethacrylate (manufactured by Sigma-Aldrich), 25.6 parts by weight of 2-hydroxymethacrylate, 6 parts by weight of diethyl methoxyborane (manufactured by Sigma-Aldrich), and 19 parts by weight of manganese(III) acetylacetonate (transesterification catalyst, manufactured by Tokyo Chemical Industry Co., Ltd.), followed by curing at 120°C for 4 hours.

[0050] Example 3 A resin composite 101 (FIG. 1) was produced in the same manner as in Example 1, except that a phenolic resin (having hydroxyl groups, the target functional groups, on the surface and inside) was used instead of urethane as the second resin member 2 (FIG. 1). When peeling was attempted in the same manner as in Example 1, peeling was not possible before heating, but peeling was easily achieved immediately after heating. This confirmed high bonding strength and high recyclability. The phenolic resin was obtained by curing DG-630 (manufactured by DIC) at 180°C for 4 hours.

[0051] <Comparative Example 1> A resin composite was produced in the same manner as in Example 1, except that the amount of acid anhydride used was 100 mol % (equivalent in stoichiometric ratio) relative to the amount of epoxy compound used. In the first resin member of Comparative Example 1, the epoxy compound and acid anhydride reacted in stoichiometric ratio during production, and the first resin member did not have a dynamic covalent bond.

[0052] When peeling was attempted in the same manner as in Example 1, peeling was easily achieved without applying a large force both before and immediately after heating. This is thought to be because the first resin member did not have a dynamic covalent bond, and therefore bonding between the first resin member and the second resin member 2 using a dynamic covalent bond was not performed.

[0053] <Comparative Example 2> A resin composite was prepared in the same manner as in Example 1, except that an acrylic resin without a hydroxyl group (an example of a target functional group) was used as the second resin member. In Comparative Example 2, the first resin member 1 has a dynamic covalent bond, but the second resin member does not have a target functional group capable of bonding with the dynamic covalent bond.

[0054] When peeling was attempted in the same manner as in Example 1, peeling was easily achieved without applying a large force both before and immediately after heating. This is thought to be because the second resin member did not have the target functional group, and bonding between the second resin member and the first resin member using a dynamic covalent bond was not achieved.

[0055] From the above results, it is clear that high bonding strength and high recyclability can be achieved by bonding different types of resins together using dynamic covalent bonds. [Explanation of symbols]

[0056] 1 First resin member 2 Second resin member 101 Resin composite

Claims

1. a first resin member having a dynamic covalent bond that can be reversibly dissociated or bonded; a second resin member that is a resin different from the first resin member and has, at least on its surface, a target functional group that can bond with the dynamic covalent bond; Equipped with the first resin member and the second resin member are bonded to each other by the dynamic covalent bond and a covalent bond via the target functional group; The second resin member includes a second resin that is a urethane having a hydroxyl group as the target functional group. A resin composite characterized by:

2. The second resin member further has the target functional group inside. The resin composite according to claim 1 .

3. The first resin member includes a first resin that is an epoxy resin. The resin composite according to claim 1 or 2.

4. The first resin member includes fibers. The resin composite according to claim 1 or 2.

5. a first resin member having a dynamic covalent bond that can be reversibly dissociated or bonded, and a second resin member that is a resin different from the first resin member and has a target functional group that can bond with the dynamic covalent bond at least on its surface, and at least the contacting portion is heated, thereby bonding the first resin member and the second resin member together by a covalent bond via the dynamic covalent bond and the target functional group; The second resin member includes a second resin that is a urethane having a hydroxyl group as the target functional group. A method for producing a resin composite, comprising:

6. A resin composite is provided which comprises a first resin member having a dynamic covalent bond that can be reversibly dissociated or bonded, and a second resin member which is a resin different from the first resin member and has a target functional group that can bond with the dynamic covalent bond at least on its surface, wherein the first resin member and the second resin member are bonded together by a covalent bond via the dynamic covalent bond and the target functional group, and by heating at least the covalent bond portion, the target functional group is dissociated from the dynamic covalent bond, and the resin composite is disassembled into the first resin member and the second resin member. A method for dismantling a resin composite.

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