Method and apparatus for decomposing and recycling thermosetting resin composite materials, and composition used therefor

Abstract

Disclosed are a method and apparatus for decomposing and recycling thermosetting resin composites, as well as compositions and kits for use therein, comprising the steps of pretreating a thermosetting resin composite by placing it in a formic acid or hydrogen peroxide solution, and then immersing the pretreated thermosetting resin composite in a hydrogen peroxide or formic acid solution for main treatment, wherein the aqueous solutions used in the pretreatment and main treatment are different. Unlike conventional chemical decomposition methods, this method significantly shortens the decomposition reaction time even under low temperature and atmospheric pressure conditions, overcomes the difficulties of building mass production facilities due to the odor of the chemical solution and corrosion of materials, and maintains reaction performance despite reducing the concentration of the chemical solution, significantly increasing the number of times the solution can be used. This allows for a dramatic reduction in production costs.

Description

[Technical Field]

[0001] This specification relates to a method and apparatus for decomposing and recycling thermosetting resin composite materials, and an aqueous solution composition used therein. Specifically, the present specification relates to a method and apparatus for decomposing and recycling thermosetting resin composite materials, which can effectively decompose and reuse composite materials, in particular composite materials formed by impregnating and curing carbon fibers with thermosetting resins, using an environmentally friendly aqueous solution-based chemical reaction, and an aqueous solution composition used therein. [National research and development project that supported this invention] [Project unique number]1415160950 [Project number] 20183010025470 [Department name] Ministry of Trade, Industry and Energy [Name of issue management (specialized organization)] Korea Energy Technology Evaluation Institute [Research Project Name] New and Renewable Energy Core Technology Development (R&D) [Research title] Development of recovery / added value technology for wind power composite blade fibers and organic materials using chemical decomposition methods, and development of disposal / reuse standards [Contribution rate] 1 / 4 [Name of project executing organization] Korea Institute of Science and Technology [Research Period] 2018.10.01~2019.03.31 [National research and development project that supported this invention] [Project unique number]1415163320 [Project number] 20183010025470 [Department name] Ministry of Trade, Industry and Energy [Name of issue management (specialized organization)] Korea Energy Technology Evaluation Institute [Research Project Name] New and Renewable Energy Core Technology Development (R&D) [Research title] Development of recovery / added value technology for wind power composite blade fibers and organic materials using chemical decomposition methods, and development of disposal / reuse standards [Contribution rate] 1 / 4 [Name of project executing organization] Korea Institute of Science and Technology [Research period] 2019.04.01~2019.12.31 [National research and development project that supported this invention] [Project unique number]1415166564 [Project number] 20183010025470 [Department name] Ministry of Trade, Industry and Energy [Name of issue management (specialized organization)] Korea Energy Technology Evaluation Institute [Research Project Name] New and Renewable Energy Core Technology Development (R&D) [Research title] Development of recovery / added value technology for wind power composite blade fibers and organic materials using chemical decomposition methods, and development of disposal / reuse standards [Contribution rate] 1 / 4 [Name of project executing organization] Korea Institute of Science and Technology [Research Period] 2020.01.01~2020.12.31 [National research and development project that supported this invention] [Project unique number]1415169648 [Project number] 20012817 [Department name] Ministry of Trade, Industry and Energy [Name of issue management (specialized organization)] Korea Institute for Industrial Technology Evaluation and Management [Research Project Name] Material and Parts Technology Development (R&D) [Research title] Development of manufacturing technology for functional parts with cost reduction of 15% or more through upcycling of carbon fiber and intermediate materials [Contribution rate] 1 / 4 [Name of project executing organization] Envioneer Co., Ltd. [Research Period] 2020.08.01~2021.02.28 [Background technology]

[0002] Thermosetting resins are widely used in composite materials such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), etc. The use of such composite materials is gradually increasing in a wide range of industrial fields, including the automotive, aerospace, and new energy fields. In particular, the rapid spread of eco-friendly cars is expected to lead to further increases in their use due to the need for lighter vehicles, and therefore the need for their disassembly and recycling is increasing.

[0003] However, due to their properties, thermosetting resins are difficult to recycle because once they harden, they are difficult to dissolve in solvents unless heat is applied. Typical thermosetting resins include polyurethane and epoxy resin.

[0004] Conventionally, methods for processing such thermosetting resin composite materials have been broadly divided into thermal decomposition and chemical decomposition methods.

[0005] The pyrolysis method has been used by Japanese companies such as Toray and Teijin, as well as companies such as Adherent Technology (USA), Procotex (France), and ELG Carbon Fiber (UK), and is still in use today. However, the use of the pyrolysis process is gradually declining because it requires high temperatures of over 500°C and is not environmentally friendly, as it produces substances that are harmful to the human body.

[0006] On the other hand, chemical decomposition methods include those based on organic solvents and those using special process conditions such as supercritical or subcritical processes.

[0007] However, organic solvent-based methods also have the problem of being environmentally unfriendly, and such organic solvent-based processing solutions often use expensive solutions (e.g., benzyl alcohol) or have limited reuse, which increases production costs.

[0008] Furthermore, in the case of supercritical conditions, the process is carried out under high pressure, which may pose a risk to workers and increases the cost of installing and maintaining safety equipment and devices, making it uneconomical.

[0009] In recent years, a technology has been developed in which treatment is carried out under mild conditions using mainly water and with the exclusion of organic solvents as much as possible (Patent Document 1).

[0010] However, in the case of the chemical method, the actual decomposition efficiency is not high, the treatment takes a long time, and it is practically impossible to use it in a large-scale treatment process other than a laboratory scale.

[0011] Furthermore, even under mild conditions, the chemical solutions used are extremely difficult to handle, limiting their practical application. For example, the strong odor of the chemical solutions themselves makes work difficult, and even when installing production equipment and carrying out the process, complaints are received from surrounding companies despite the installation of dust collectors, scrubbers, and other equipment. These practical issues are hindering the application of the technology.

[0012] Furthermore, there are problems such as the need to use expensive materials (e.g., titanium) to protect against corrosion when constructing various facilities such as reactors, pumps, piping, and valves, as well as measurement and control equipment, and the need to frequently replace such facilities and measurement and control equipment.

[0013] Therefore, the present inventors have conducted extensive research into a decomposition and recycling technology for thermosetting resin composite materials, which is an aqueous solution-based decomposition method that does not require organic solvents, and which can decompose the materials under mild conditions, has high decomposition efficiency, is applicable to large-scale treatment facilities, has no strong odor, is easy to handle and use, and is not corrosive, reducing the need for replacement of related equipment. As a result, the present inventors have arrived at the present invention. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Korean Patent No. 1861095 Summary of the Invention [Problem to be solved by the invention]

[0015] In one aspect, an exemplary embodiment of the present invention provides a method and apparatus for decomposing and recycling thermosetting resin composites, a composition used therefor, and a kit including the same, which are capable of decomposing under mild conditions of low temperature and atmospheric pressure while using an aqueous solution-based decomposition method without using an organic solvent, have high decomposition efficiency, and are applicable to large-scale processing facilities.

[0016] In another aspect, an exemplary embodiment of the present invention provides a method and apparatus for decomposing and recycling a thermosetting resin composite material, a composition used therefor, and a kit including the same, which can significantly improve problems of handling and corrosion, and can also significantly increase the chemical reaction rate compared to conventional methods, thereby improving productivity.

[0017] In another aspect, an exemplary embodiment of the present invention provides a method and apparatus for decomposing and recycling a thermosetting resin composite, which allows for excellent reusability of an aqueous solution used in the decomposition treatment of a thermosetting resin composite, and allows for easy control of the treatment process and treatment conditions, a composition used therefor, and a kit including the same. [Means for solving the problem]

[0018] In an example embodiment of the present invention, there is provided a method for decomposing a thermosetting resin composite material, the method comprising: a step of pretreating a thermosetting resin composite material by immersing the pretreated thermosetting resin composite material in a formic acid solution or a hydrogen peroxide solution (in a formic acid solution or a hydrogen peroxide solution); and a step of main treatment (main treatment) by immersing the pretreated thermosetting resin composite material in a hydrogen peroxide solution or a formic acid solution (in a hydrogen peroxide solution or a formic acid solution), wherein the aqueous solutions used in the pretreatment and the main treatment are different from each other.

[0019] In addition, an example embodiment of the present invention provides an apparatus for decomposing a thermosetting resin composite material, the apparatus comprising: a pre-impregnation tank for pre-impregnating a thermosetting resin composite material with a formic acid solution (or aqueous formic acid solution) or an aqueous hydrogen peroxide solution; a pretreatment tank connected to the pre-impregnation tank, which is a pretreatment tank for containing (carrying) a formic acid solution or an aqueous hydrogen peroxide solution and to which the thermosetting resin composite material obtained (or harvested) from the pre-impregnation tank is delivered; and a main treatment tank connected to the pretreatment tank, which is a main treatment tank for containing (carrying) a hydrogen peroxide solution or an aqueous formic acid solution and to which the thermosetting resin composite material obtained (or harvested) from the pre-treatment tank is delivered; wherein the aqueous solutions contained in the pre-treatment tank and the aqueous solutions contained in the main treatment tank are different from each other.

[0020] In addition, an example embodiment of the present invention provides a kit for decomposition of a thermosetting resin composite material, the kit comprising: a pre-impregnation composition for pre-impregnation, which contains a formic acid solution (or an aqueous formic acid solution) or a hydrogen peroxide solution (or an aqueous hydrogen peroxide solution); a pretreatment composition for pre-treatment, which contains a formic acid solution or an aqueous hydrogen peroxide solution; and a treatment composition for treatment, which contains an aqueous hydrogen peroxide solution or an aqueous formic acid solution; wherein the aqueous solution of the pretreatment composition and the aqueous solution of the treatment composition are different from each other.

[0021] In addition, an example embodiment of the present invention provides a composition for decomposing a thermosetting resin composite material, which comprises an aqueous hydrogen peroxide solution or an aqueous formic acid solution, preferably an aqueous hydrogen peroxide solution containing 0.1 to 2 wt% of a radical initiator. [Effects of the Invention]

[0022] Unlike conventional chemical decomposition methods, exemplary embodiments of the present invention significantly reduce the decomposition reaction time even under mild conditions of low temperature and atmospheric pressure. They also address the challenges of constructing mass production facilities due to the odor of the chemical solution and corrosion of materials. They also maintain reaction performance despite lowering the concentration of the chemical solution, significantly increasing the number of times the solution can be used. Furthermore, the aqueous solution used in the decomposition of thermosetting resin composites can be easily reused, and the process and control of the processing conditions are easy. This significantly reduces production costs. [Brief explanation of the drawings]

[0023] [Figure 1]1 is a result table showing the corrosivity of alternative solutions used in exemplary embodiments of the present invention compared to the corrosivity of existing solutions. [Figure 2] 10 is a photograph showing the improvement in reaction rate when using a substitute solution in Experiment 1. [Figure 3a] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3b] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3c] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3d] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3e] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3f] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 3g] These are photographs of CFRP before and after decomposition in Experiment 2. [Figure 4a] CFRP photographs before and after decomposition in Experiment 3. [Figure 4b] CFRP photographs before and after decomposition in Experiment 3. [Figure 4c] CFRP photographs before and after decomposition in Experiment 3. [Figure 4d] CFRP photographs before and after decomposition in Experiment 3. [Figure 4e] CFRP photographs before and after decomposition in Experiment 3. [Figure 4f] CFRP photographs before and after decomposition in Experiment 3. [Figure 4g] CFRP photographs before and after decomposition in Experiment 3. [Figure 4h] CFRP photographs before and after decomposition in Experiment 3. [Figure 5] The results of Experiment 4 show that pre-impregnation shortens the decomposition time. [Figure 6] 1 is a graph showing the change in concentration and pH as a function of heating (90° C.) time with or without the addition of a buffer solution in the case of a solution (Solution D) used in an exemplary example of the present invention. [Figure 7]1 is a graph showing the results of repeated decomposition of a solution (Solution D) used in an exemplary embodiment of the present invention while adjusting the concentration by adding a buffer solution (heating temperature: 90°C, reaction time: approximately 5 hours per cycle). DETAILED DESCRIPTION OF THE INVENTION

[0024] Term definition As used herein, the term "thermosetting resin composite" refers to various composite materials containing a thermosetting resin, such as an epoxy resin composite containing a cured epoxy resin and various fillers such as carbon fiber.

[0025] In this specification, recycling includes the process of chemically treating and decomposing thermosetting resin composite materials.

[0026] The term decomposition used in this specification and particularly in the claims may mean not only decomposition itself but also decomposition and subsequent reuse (recycling) after decomposition.

[0027] In this specification, decomposition and recycling is defined to include one or more of the decomposition and recycling processes.

[0028] As used herein, "pre-impregnation" refers to impregnation for a certain period of time at atmospheric pressure and room temperature, which is not considered a substantial heat treatment. The temperature that is not considered a substantial heat treatment may be room temperature without any heating or a temperature of 40°C or less, which is not considered a substantial heat treatment, but is preferably room temperature. At this temperature and atmospheric pressure, the thermosetting resin composite material is immersed in an aqueous solution such as a formic acid solution or a hydrogen peroxide solution for a certain period of time.

[0029] In this specification, the term "pretreatment" refers to carrying a thermosetting resin composite material in an aqueous solution such as a formic acid aqueous solution or a hydrogen peroxide aqueous solution at atmospheric pressure and a temperature of 80°C to 120°C, preferably below 100°C, which is the boiling point of water, for a certain period of time.

[0030] In this specification, the present treatment means that the pretreated thermosetting resin composite material is held in an aqueous solution such as a formic acid aqueous solution or a hydrogen peroxide aqueous solution at atmospheric pressure and at a temperature of 80°C to 120°C, preferably below 100°C, which is the boiling point of water, for a certain period of time.

[0031] In this specification, solution A refers to an aqueous solution of acetic acid. In this specification, Solution B refers to an aqueous solution of sodium hypochlorite. As used herein, solution C refers to an aqueous solution of formic acid. As used herein, solution D refers to an aqueous solution of hydrogen peroxide.

[0032] As used herein, the radical initiator refers to a substance capable of generating radical species and promoting radical reactions under mild conditions, and is further added to the aqueous formic acid solution and / or aqueous hydrogen peroxide solution used in the pre-impregnation, pre-treatment and / or main treatment processes in example embodiments of the present invention.

[0033] In this specification, the reusability of an aqueous solution means that the aqueous solution used in each of the steps of pre-impregnation, pre-treatment and main treatment can be reused in the same steps.

[0034] As used herein, concentration is expressed as a percentage of the weight of an added substance relative to the total mass of the solution.

[0035] Description of exemplary embodiments Hereinafter, exemplary embodiments of the present invention will be described in detail. The present inventors recognized the problems of the existing chemical decomposition methods for thermosetting resin composites, such as harsh process conditions, difficulty in handling the chemical solutions, corrosiveness, and increased costs of the chemical solutions, and as a result of intensive research to continuously improve these problems, they arrived at the present invention.

[0036] More specifically, a method that has been used until recently for chemically recycling carbon fiber composite materials involves, for example, pretreating the material with an aqueous solution of acetic acid, then treating it with an aqueous solution containing sodium hypochlorite to decompose the thermosetting resin, and then recovering the carbon fibers remaining in the solution. However, this method has had considerable problems in practical application.

[0037] That is, in the above method, the strong corrosiveness and odor of acetic acid (more precisely, glacial acetic acid) itself pose serious limitations on workers' handling of the solution and on setting up reaction equipment. Furthermore, in the case of sodium hypochlorite, the problem of corrosiveness becomes even more serious, causing rapid corrosion even in alloys such as SUS316, which has fire resistance, and there are many difficulties in setting up reaction equipment.

[0038] Therefore, in an exemplary embodiment of the present invention, in order to improve the above-mentioned problems such as ease of handling and corrosiveness while achieving high decomposition efficiency, an alternative solution (formic acid aqueous solution and hydrogen peroxide aqueous solution) is used, and stepwise decomposition of pre-treatment and main treatment is performed, followed by a pre-impregnation process before the pre-treatment.

[0039] For example, a pretreatment may be performed using a formic acid aqueous solution or a hydrogen peroxide aqueous solution instead of acetic acid, and a main treatment may be performed using a hydrogen peroxide aqueous solution or a formic acid aqueous solution instead of sodium hypochlorite. From the viewpoints of reusability, mass productivity, ease of handling such as reaction control, and decomposition efficiency, the aqueous solutions used in the pretreatment and main treatment are different from each other.

[0040] This dramatically improves ease of handling and corrosiveness, and as will be described later, the chemical reaction rate is significantly increased compared to conventional methods, resulting in a higher decomposition rate and improved productivity. Furthermore, as reusability increases, mass production, which allows for large-scale processing, is also improved.

[0041] FIG. 1 is a table showing the corrosivity of alternative solutions used in exemplary embodiments of the present invention compared to the corrosivity of existing solutions.

[0042] As shown in FIG. 1, conventional solutions such as acetic acid and sodium hypochlorite caused corrosion problems with both SUS 304 and SUS 316 alloys as the reaction times increased. However, formic acid and hydrogen peroxide used in exemplary embodiments of the present invention performed well without corrosion problems and allowed for faster treatment at a reaction temperature below 100°C, the boiling point of water.

[0043] The following corrosivity results table shows a comparison of the performance and cost of the pretreatment solution (Solution C: formic acid aqueous solution) and the solution used in the main process (Solution D: hydrogen peroxide aqueous solution) in the exemplary embodiment of the present invention with the existing pretreatment solution (Solution A: acetic acid aqueous solution) and the solution used in the main process (Solution B: sodium hypochlorite aqueous solution).

[0044] [Table 1]

[0045] As described above, in the illustrative embodiment of the present invention, when the alternative solutions (formic acid aqueous solution and hydrogen peroxide aqueous solution) are used, the corrosiveness is reduced compared to conventional solutions, which makes it easier to select materials for constructing the reaction equipment. In addition, as will be described later, the alternative solutions have excellent decomposition efficiency and can easily decompose thermosetting resin composite materials that are difficult to decompose.

[0046] Meanwhile, in example embodiments, the composite material may be pre-impregnated (within about 10 hours) in an aqueous formic acid solution or an aqueous hydrogen peroxide solution before being introduced into the decomposition reaction, thereby further shortening the reaction time for the pretreatment and main treatment.

[0047] Specifically, in an example embodiment, a method for recycling a thermosetting resin composite material includes the steps of pretreating the thermosetting resin composite material by placing it in a formic acid solution or a hydrogen peroxide solution, and then immersing the pretreated thermosetting resin composite material in a hydrogen peroxide solution or a formic acid solution for main treatment. As described above, the pretreatment solution and the main treatment solution are different from each other.

[0048] According to example embodiments, the pre-impregnation may be carried out at room temperature (or room temperature) and atmospheric pressure (or atmospheric pressure) for 17 hours or less, preferably 10 hours or less, depending on the type of thermosetting resin composite material to be decomposed. For example, the pre-impregnation may be carried out for more than 0 hours to 10 hours or less, 1 to 9 hours, 2 to 8 hours, 3 to 7 hours, or 4 to 6 hours. Non-limiting examples of the pre-impregnation may be carried out at room temperature and atmospheric pressure for 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5 hours or less, 4 hours or less, 3 hours or less, 2 hours or less, or 1 hour or less. Furthermore, the pre-impregnation may be carried out for more than 0 hours, 1 hour or more, 2 hours or more, 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more, 7 hours or more, 8 hours or more, or 9 hours or more.

[0049] According to example embodiments, the pretreatment may be carried out at atmospheric pressure and 80 to 120°C, preferably 80°C to less than 100°C, 85 to 95°C, or 90°C, for 1 to 6 hours.

[0050] As a non-limiting example, the pretreatment temperature may be 80°C or higher, 85°C or higher, 90°C or higher, or 95°C or higher, and may be 120°C or lower, 115°C or lower, 110°C or lower, or 105°C or lower, preferably lower than 100°C, 95°C or lower, 90°C or lower, or 85°C or lower.

[0051] As non-limiting examples, the pretreatment time may be 1 hour or more, 1.5 hours or more, 2 hours or more, 2.5 hours or more, 3 hours or more, 3.5 hours or more, 4 hours or more, 4.5 hours or more, 5 hours or more, or 5.5 hours or more, and may be 6 hours or less, 5.5 hours or less, 5 hours or less, 4.5 hours or less, 4 hours or less, 3.5 hours or less, 3 hours or less, 2.5 hours or less, 2 hours or less, or 1.5 hours or less.

[0052] According to example embodiments, the treatment may be carried out at atmospheric pressure and 80 to 120°C, preferably 80 to less than 100°C, 85 to 95°C, or 90°C, for 1 to 3 hours.

[0053] As a non-limiting example, the temperature of the treatment may be 80°C or higher, 85°C or higher, 90°C or higher, or 95°C or higher, and may be 120°C or lower, 115°C or lower, 110°C or lower, or 105°C or lower, preferably lower than 100°C, 95°C or lower, 90°C or lower, or 85°C or lower.

[0054] As a non-limiting example, the duration of the treatment may be 1 hour or more, 1.5 hours or more, 2 hours or more, or 2.5 hours or more, and may be 3 hours or less, 2.5 hours or less, 2 hours or less, or 1.5 hours or less.

[0055] According to example embodiments, the concentration of formic acid in the formic acid aqueous solution may be 50% or more and less than 100%, but from an environmental viewpoint, it may be preferably 90% or less, or less than 85%, and from a reactivity viewpoint, it may be 50% or more.

[0056] As a non-limiting example, the concentration of formic acid may be, for example, 50 to 90%, for example, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, or 55% or less, and may be 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, or 85% or more.

[0057] According to example embodiments, the concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution may be 20% or more and 50% or less, but from an environmental perspective, it may be preferably less than 35%, and from a reactivity perspective, it may be 30% or more, since a concentration above 50% may cause an explosion.

[0058] By way of non-limiting example, the concentration of hydrogen peroxide may be 34.5% or less, 34% or less, 33.5% or less, 33% or less, 32.5% or less, 32% or less, 31.5% or less, 31% or less, 30.5% or less.

[0059] By way of non-limiting example, the concentration of hydrogen peroxide may be 30% or greater, 30.5% or greater, 31% or greater, 31.5% or greater, 32% or greater, 32.5% or greater, 33% or greater, 33.5% or greater, or 34% or greater.

[0060] On the other hand, as can be seen in the experimental examples described below, it was confirmed that in aqueous solution-based decomposition, using specific solutions in a specific sequence during pre-impregnation, pre-treatment, and main treatment can make a big difference in the actual decomposition efficiency. Although the reason for this has not been clearly investigated, it is thought to be due to the fact that in the case of aqueous solution-based decomposition, the decomposition mechanism and efficiency are affected by the types of chemicals used in each process of pre-impregnation, pre-treatment, and main treatment.

[0061] Furthermore, the reaction can be carried out more efficiently by changing the order of the treatment with the formic acid aqueous solution and the hydrogen peroxide aqueous solution depending on the type of thermosetting resin composite material to be decomposed and recycled.

[0062] For example, in the case of a material that is extremely difficult to decompose, such as CFRP that constitutes the fuselage of an aircraft, it is preferable to use a material that has a relatively highly efficient decomposition sequence in addition to adding a radical initiator, which will be described later.

[0063] Meanwhile, if a trace amount of a radical initiator is used in one or more of the above-mentioned pre-impregnation, pretreatment, and main treatment processes, especially in one or more of the pretreatment and main treatment processes, the decomposition efficiency can be dramatically increased, for example, to 10% or more. Considering that it is extremely difficult to increase the decomposition efficiency alone while keeping other conditions constant in the chemical decomposition process of thermosetting resin composite materials, it is surprising that the decomposition efficiency can be increased by about 10% by just adding a trace amount of a radical initiator.

[0064] Although the mechanism has not been clearly elucidated, it is thought that the radical initiator involved in the radical reaction during the decomposition of the thermosetting resin composite material during the pre-impregnation, pre-treatment and / or main treatment using Solution C and / or Solution D increases the decomposition efficiency.

[0065] In an illustrative embodiment, the radical initiator is preferably an azo compound or an organic peroxide in terms of increasing decomposition efficiency.

[0066] As a non-limiting example, the radical initiator azo compound may be azobisisobutyronitrile (AIBN).

[0067] As non-limiting examples, the organic peroxide radical initiator may be benzoyl peroxide (BPO), acetyl peroxide, dilauroyl peroxide, or the like.

[0068] In one illustrative embodiment, the radical initiator in the formic acid aqueous solution or the hydrogen peroxide aqueous solution is preferably added in an amount of 0.01 to 2 wt% from the viewpoint of decomposition efficiency. If an excessive amount exceeding 2 wt% is used, it may become difficult to control the chemical reaction due to excessive reactivity.

[0069] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in a formic acid aqueous solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in a hydrogen peroxide aqueous solution containing a radical initiator; and main-treating the pre-treated thermosetting resin composite material by placing it in a formic acid aqueous solution.

[0070] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in a formic acid aqueous solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in a hydrogen peroxide aqueous solution; and main-treating the pre-treated thermosetting resin composite material by placing it in a formic acid aqueous solution to which a radical initiator has been added.

[0071] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in an aqueous hydrogen peroxide solution containing a radical initiator; and main-treating the pre-treated thermosetting resin composite material by placing it in an aqueous formic acid solution.

[0072] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in an aqueous hydrogen peroxide solution; and main-treating the pre-treated thermosetting resin composite material by placing it in an aqueous formic acid solution containing a radical initiator.

[0073] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in an aqueous formic acid solution containing a radical initiator; and pre-treating the pre-treated thermosetting resin composite material by placing it in an aqueous hydrogen peroxide solution.

[0074] In an illustrative embodiment, a decomposition process sequence of the method for decomposing a thermosetting resin composite material may include the steps of pre-impregnating a thermosetting resin composite material in an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermosetting resin composite material by placing it in an aqueous formic acid solution; and main-treating the pre-treated thermosetting resin composite material by placing it in an aqueous hydrogen peroxide solution containing a radical initiator.

[0075] Meanwhile, in an example embodiment, in order to maintain continuous decomposition characteristics, the concentration and / or pH of the aqueous hydrogen peroxide solution may be adjusted to maintain it within a certain range, and a buffer solution may be used to adjust the concentration and / or pH.

[0076] As a non-limiting example, as the reaction using an aqueous hydrogen peroxide solution proceeds during the pretreatment or main treatment, the concentration and pH fluctuate with a similar correlation, and to compensate for this and maintain sustained decomposition properties, a buffer solution may be used, which may include one or more of citric acid, tartaric acid, and phosphoric acid.

[0077] As a non-limiting example, the concentration of the aqueous hydrogen peroxide solution is preferably less than 35% and not less than 30% of that before the decomposition treatment.

[0078] According to example embodiments, the decomposition rate of the thermosetting resin composite material may be measured by thermogravimetric analysis (TGA), which can determine the decomposition rate of organic matter. The decomposition rate measured by TGA may be 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, or 97% or more, preferably 98% or more or 99% or more, and most preferably 100%.

[0079] The decomposition rate is determined by TGA analysis of the finally recovered (after drying) carbon fiber (recycled carbon fiber), and the closer the organic and inorganic residues are to 0%, the closer the decomposition rate is to 100%.

[0080] Meanwhile, an apparatus for decomposing a thermosetting resin composite material according to an example embodiment of the present invention may include a pre-treatment section (or pre-treatment region) in which a thermosetting resin composite material is pre-treated by being placed in a formic acid solution (or aqueous formic acid solution) or a hydrogen peroxide solution, and a main treatment section (or main treatment region) in which the pre-treated thermosetting resin composite material is placed in a hydrogen peroxide solution or a formic acid solution for main treatment. The pre-treatment solution and the main treatment solution are different solutions.

[0081] In an example embodiment, the apparatus may further include a pre-impregnation section (or pre-impregnation area) for pre-impregnating the thermosetting resin composite material before pre-treatment with a formic acid solution or a hydrogen peroxide solution.

[0082] In one illustrative embodiment, the decomposition device for a thermosetting resin composite may include: a pre-impregnation tank for pre-impregnating a thermosetting resin composite with a formic acid solution (or aqueous formic acid solution) or an aqueous hydrogen peroxide solution; a pre-treatment tank connected to the pre-impregnation tank, for example, by a conveyor belt, to which the thermosetting resin composite material obtained from the pre-impregnation tank is sent and which contains (or carries) a formic acid solution or an aqueous hydrogen peroxide solution; and a main treatment tank connected to the pre-treatment tank, for example, by a conveyor belt, to which the thermosetting resin composite material obtained from the pre-treatment tank is sent and which contains (or carries) an aqueous hydrogen peroxide solution or an aqueous formic acid solution.

[0083] Meanwhile, in an example embodiment of the present invention, a disassembly kit for a thermosetting resin composite material may be provided.

[0084] The kit includes a pre-impregnation composition for pre-impregnation, which contains a formic acid solution (or an aqueous formic acid solution) or a hydrogen peroxide solution; a pretreatment composition for pre-treatment, which contains a formic acid solution or an aqueous hydrogen peroxide solution; and a main treatment composition for main treatment, which contains an aqueous hydrogen peroxide solution or an aqueous formic acid solution. The aqueous solutions of the pretreatment composition and the main treatment composition are configured to be different from each other.

[0085] In an exemplary embodiment, the kit may further include a radical initiator in an aqueous hydrogen peroxide solution or an aqueous formic acid solution, particularly preferably an aqueous hydrogen peroxide solution, wherein the radical initiator is preferably added in an amount of 0.01 to 2 wt % or less in the aqueous hydrogen peroxide solution or the aqueous formic acid solution.

[0086] Hereinafter, specific examples according to exemplary embodiments of the present invention will be described in more detail. It should be understood that the present invention is not limited to the following examples, and various embodiments can be embodied within the scope of the appended claims. The following examples are provided merely to complete the disclosure of the present invention and to enable those skilled in the art to easily practice the invention.

[0087] [Experiment 1] In this experiment 1, we investigated whether there was any improvement in decomposition efficiency when using alternative solutions C and D compared to the existing solutions A and B.

[0088] First, aircraft CFRP scrap (crushed material) was used as the raw material before decomposition. For reference, Figure 2 shows a photograph of the CFRP scrap before decomposition.

[0089] The solutions used for decomposition were a glacial acetic acid solution (Solution A - 99.9%) and a sodium hypochlorite solution (Solution B - 12%). Additionally, a formic acid solution (Solution C - 80%) and a hydrogen peroxide solution (Solution D - 34.5%) were used. Solutions A, B, C, and D were used in a volume ratio of 1:20 relative to the CFRP.

[0090] For reference, the volume ratio of the solution to the treated composite material in the pre-impregnation, pretreatment, and main treatment may be 1 (volume of composite material):10 (volume of solution) or more, for example, 1 (volume of composite material):10 (volume of solution) to 1 (volume of composite material):30 (volume of solution). However, from the viewpoint of cost reduction, it is preferable that the volume ratio of the solution is as low as possible.

[0091] Figure 2 shows photographs of the results of Experiment 1, showing the improvement in reaction rate when using the alternative solution. Figure 2a shows the results for the existing solution, and Figure 2b shows the results for this example.

[0092] As shown in FIG. 2, in the case of the conventional solution described above, it was difficult to remove the reaction residue even when the total reaction time of the pretreatment (Step-1) and main treatment (Step-2) exceeded 10 hours (see FIG. 2a), whereas in the exemplary embodiment of the present invention, the reaction residue could be easily removed after a total reaction time of the pretreatment (Step-1) and main treatment (Step-2) of 4 hours (see FIG. 2b).

[0093] [Experiment 2] In Experiment 2, the changes in decomposition efficiency were measured when the pre-impregnation decomposition sequence was changed based on the sequence of using solution C in the pretreatment and solution D in the main treatment, when the pretreatment and main treatment times were changed, and when a radical initiator was also used.

[0094] First, an aircraft CFRP plate was used as the raw material before decomposition. Its dimensions were 30 × 30 × 5 mm (1 g). For reference, Figure 3a shows a photograph of the CFRP plate before decomposition.

[0095] The solutions used for decomposition were a formic acid solution (solution C - 80%) and a hydrogen peroxide solution (solution D - 34.5%). Solutions C and D were used in a volume ratio of 1:20 to the CFRP.

[0096] When pre-impregnation was carried out, it was carried out at room temperature and atmospheric pressure for 17 hours, and both pre-treatment and main treatment were carried out at atmospheric pressure and 90°C.

[0097] As a radical initiator, AIBN was used in an amount of 1 wt % in each aqueous solution.

[0098] The decomposition efficiency was measured by thermogravimetric analysis (TGA). For reference, the analyzer used for TGA analysis was a SCINCO TGA N-1000, with a temperature range of RT to 800°C, an EGA furnace, a heating rate of 10°C, and a N2 atmosphere. The TGA analysis method was the same for multiple experiments.

[0099] The sequence, whether or not a radical initiator was added, and the decomposition rate for each example in Experiment 2 are as shown in the table below. Note that all other conditions in each sequence were the same except for the conditions shown in the table below. Meanwhile, photographs of Examples 1 to 6 after decomposition are shown in Figures 3b to 3g, respectively.

[0100] [Table 2]

[0101] As can be seen from the above, when Examples 1 and 2 are compared, it can be seen that the decomposition efficiency improves by about 10% when pre-impregnation with solution D is further performed, with other conditions kept the same.

[0102] Furthermore, comparing Examples 1 and 3, when the pretreatment time was increased by 1 hour and the main treatment time was also increased by 1 hour, the decomposition efficiency reached 100% in the D → C → D sequence. However, without pre-impregnation with D solution, the decomposition efficiency was only 81.8%, even when the pretreatment time was increased by 1 hour and the main treatment time was also increased by 1 hour. Therefore, even if the decomposition time is increased in the pre-treatment sequence with C solution and the main treatment sequence with D solution, there is a benefit to pre-impregnation with D solution. For reference, although increasing the decomposition time is not desirable from the perspectives of decomposition, recycling efficiency, and cost of thermosetting resin composite materials, it is necessary to minimize the decomposition time and achieve high decomposition efficiency. From this perspective, the sequence of Example 6 described below shows very surprising results.

[0103] That is, Example 5 is an example in which a radical initiator was added to the pretreatment solution in comparison with Example 1, and in this case, the decomposition efficiency increased by approximately 2%. On the other hand, Example 6 is an example in which a radical initiator was added to the main treatment solution in comparison with Example 1, and in this case, the decomposition efficiency increased dramatically to 100%.

[0104] These results indicate that adding a radical initiator to solution D, especially when carrying out the D→C→D process, significantly increases the decomposition efficiency. This result is also consistent with the result in Experiment 3 below, which showed that adding a radical initiator to solution D increases the decomposition efficiency.

[0105] Meanwhile, in Experiment 2, we investigated the difference between the presence and absence of initiator (AIBN) during pre-impregnation, and confirmed that the specimens became softer when pre-impregnated with solution D + radical initiator.

[0106] [Experiment 3] In Experiment 3, the change in decomposition efficiency was measured when the pre-impregnation decomposition sequence was changed based on the sequence of using solution D in the pretreatment and solution C in the main treatment, and when a radical initiator was also used.

[0107] First, an aircraft CFRP plate was used as the raw material before decomposition. Its dimensions were 30 × 30 × 5 mm (1 g). For reference, Figure 4a shows a photograph of the CFRP plate before decomposition.

[0108] The solutions used for decomposition were a formic acid solution (solution C - 80%) and a hydrogen peroxide solution (solution D - 34.5%). Solutions C and D were used in a volume ratio of 1:20 to the CFRP.

[0109] The pre-impregnation was carried out at room temperature and atmospheric pressure, and both the pre-treatment and the main treatment were carried out at atmospheric pressure and 90°C.

[0110] As a radical initiator, AIBN was used in an amount of 1 wt % in each aqueous solution.

[0111] The decomposition efficiency was measured by thermogravimetric analysis (TGA) as in Experiment 2.

[0112] The sequence, whether or not a radical initiator was added, and the decomposition rate for each example of Experiment 3 are as shown in the table below. All other conditions for each sequence were the same except for the conditions shown in the table below.

[0113] [Table 3]

[0114] As can be seen from the above, adding a radical initiator during the pre-treatment and main treatment of the decomposition reaction significantly increases the decomposition rate (by about 10%). For reference, when recycling CFRP, it is preferable that 95% or more, and more preferably 98% or more, be decomposed.

[0115] On the other hand, when a radical initiator was added, higher decomposition efficiency was observed in a specific sequence in the decomposition reactions of the pre-impregnation and pretreatment, and the main treatment. That is, in Example 3 (C → D + initiator → C), higher decomposition efficiency was observed than in Example 5 (C → D → C + initiator).

[0116] Furthermore, in the case of Example 4 (D → D + initiator → C), a significantly higher increase in decomposition efficiency was observed compared to Example 6 (D → D → C + initiator).

[0117] As can be seen from the above, the addition of a radical initiator increases the decomposition efficiency, especially when Solution D is used as the pretreatment solution and Solution C is used as the main treatment solution. It can be seen that adding a radical initiator during pretreatment results in a greater increase in the overall decomposition efficiency.

[0118] Furthermore, when Solution D was used as the pretreatment solution and Solution C was used as the main treatment solution as described above, the highest decomposition efficiency of 99.7% was achieved under the same conditions, especially in the case of a sequence in which pre-impregnation was performed with Solution C. For reference, Figures 4b to 4h are photographs of the recycled carbon fibers after decomposition according to Examples 1 to 6 of Experiment 2, respectively.

[0119] Meanwhile, in this experiment, we also investigated the difference between the presence and absence of initiator (AIBN) added during pre-impregnation. As a result, we found that there was little difference in the effect when pre-impregnating with solution C + radical initiator, but it was confirmed that the specimen became softer when pre-impregnating with solution D + radical initiator.

[0120] Taking all of the above into consideration, it is believed that the radical initiator exerts a higher increasing effect when added to solution D.

[0121] [Experiment 4] On the other hand, the reaction can be made more efficient by changing the decomposition sequence depending on the properties of the raw material (waste CFRP), and the reaction time for pre-treatment and main treatment can be further shortened by pre-impregnating the raw material in solution C or D (at room temperature and pressure, for 17 hours in Experiment 4) before putting it into the decomposition reaction.

[0122] In Experiment 4, the CFRP of the hydrogen tank was decomposed immediately after cutting without crushing. First, it was pre-soaked in a formic acid solution at room temperature for 17 hours. Then, it was placed in a hydrogen peroxide solution for 4 hours for pre-treatment.

[0123] After the pretreatment, the sample was placed in a formic acid solution for 1 hour to complete the treatment.

[0124] The concentrations of the solutions used were formic acid solution (solution C - 80%) and hydrogen peroxide solution (solution D - 34.5%). Solutions C and D were used in a volume ratio of 1:20 to the CFRP.

[0125] Both the pretreatment and the main treatment were carried out at atmospheric pressure and 90°C.

[0126] Figure 5 shows the results of Experiment 4, demonstrating the shortening of decomposition time by pre-impregnation. Figure 5a is a photograph of the pre-impregnated sample, and Figure 5b is a photograph of the sample without pre-impregnation. TGA analysis showed that no organic matter remained in the pre-impregnated sample, but 20% of the organic matter remained in the sample without pre-impregnation.

[0127] [Experiment 5] In this experiment 5, a buffer solution (pH=2.45) was initially added (1.17%) to compensate the pH, thereby maintaining the concentration at a constant level to sustain the degradation characteristics.

[0128] The buffer solution was prepared by dissolving 0.21 g of citric acid, 0.8 g of tartaric acid, and 0.5 g of phosphoric acid in 100 ml of water with stirring, diluting the solution to a total volume of 900 ml, and stirring again. The pH of the buffer solution was 2.45. The buffer solution was then added to Solution D after mixing to adjust the pH to 1.165.

[0129] FIG. 6 is a graph showing the change in concentration and pH as a function of heating (90° C.) time with or without the addition of a buffer solution for the solution used in an exemplary embodiment of the present invention (Solution D).

[0130] FIG. 7 is a graph showing the results of repeated decomposition of the solution (Solution D) used in an exemplary embodiment of the present invention while adjusting the concentration by adding a buffer solution (heating temperature: 90°C, reaction time: approximately 5 hours per cycle).

[0131] As can be seen from FIG. 7, the solution of the exemplary embodiment of the present invention can be repeatedly decomposed, and therefore the aqueous solution is excellent in reusability, and can be repeatedly decomposed up to seven times.

[0132] The residual percentages in Figure 7 are the residual percentages of organic matter determined by TGA analysis. The increase in buffer concentration after the third repetition in Figure 7 is due to the use of a buffer solution after the third repetition. As can be seen from Figure 7, the decomposition rate decreases as the number of repetitions increases, but the residual percentage of organic matter was very low up to the seventh repetition, but from the eighth repetition onwards no decomposition occurred at all. [Industrial Applicability]

[0133] The present specification relates to a method and apparatus for decomposing and recycling a thermosetting resin composite material, which can effectively decompose and reuse a composite material in which carbon fiber is impregnated with and cured with a thermosetting resin using an environmentally friendly aqueous solution-based chemical reaction, and an aqueous solution composition used therein.

Claims

1. Pretreating the thermosetting resin composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and A step of subjecting the pretreated thermosetting resin composite material to a main treatment by placing it in an aqueous hydrogen peroxide solution or an aqueous formic acid solution. and When a formic acid aqueous solution is used in the pretreatment, a hydrogen peroxide aqueous solution is used in the main treatment, and when a hydrogen peroxide aqueous solution is used in the pretreatment, a formic acid aqueous solution is used in the main treatment; The pretreatment involves immersing the thermosetting resin composite material in an aqueous formic acid solution or an aqueous hydrogen peroxide solution heated to 80°C to 100°C under atmospheric pressure; The main treatment is a method for decomposing a thermosetting resin composite material, in which the thermosetting resin composite material that has been subjected to the pretreatment is immersed in an aqueous hydrogen peroxide solution or an aqueous formic acid solution heated to 80°C to 100°C under normal pressure.

2. The method for decomposing a thermosetting resin composite material according to claim 1 , wherein a radical initiator is added to the aqueous solution used in one or more of the pretreatment and / or main treatment.

3. 2. The method for decomposing a thermosetting resin composite material according to claim 1, further comprising a pre-impregnation step of pre-impregnating the thermosetting resin composite material with a formic acid solution or a hydrogen peroxide solution before the pretreatment, wherein the pre-impregnation is carried out at atmospheric pressure and at 40°C or lower.

4. pre-impregnating the thermoset resin composite with an aqueous formic acid solution; pre-treating the pre-impregnated thermoset composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and a step of subjecting the pretreated thermosetting resin composite material to a main treatment in an aqueous formic acid solution; The method for decomposing a thermosetting resin composite material according to claim 3, further comprising:

5. pre-impregnating the thermoset resin composite with an aqueous formic acid solution; pre-treating the pre-impregnated thermoset resin composite in an aqueous hydrogen peroxide solution; and A step of subjecting the pre-treated thermosetting resin composite material to a main treatment by placing it in an aqueous formic acid solution to which a radical initiator is added.

4. The method for decomposing a thermosetting resin composite material according to claim 3, comprising:

6. pre-impregnating the thermoset composite with an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermoset composite material in an aqueous hydrogen peroxide solution to which a radical initiator is added; and 4. The method for decomposing a thermosetting resin composite material according to claim 3, further comprising the step of immersing the pretreated thermosetting resin composite material in an aqueous formic acid solution to carry out the main treatment.

7. pre-impregnating the thermoset composite with an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermoset resin composite in an aqueous hydrogen peroxide solution; and A step of subjecting the pre-treated thermosetting resin composite material to a main treatment by placing it in an aqueous formic acid solution to which a radical initiator is added.

4. The method for decomposing a thermosetting resin composite material according to claim 3, comprising:

8. pre-impregnating the thermoset composite with an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermoset composite material in an aqueous formic acid solution to which a radical initiator is added; and a step of subjecting the pretreated thermosetting resin composite material to a main treatment in an aqueous hydrogen peroxide solution; 4. The method for decomposing a thermosetting resin composite material according to claim 3, comprising:

9. pre-impregnating the thermoset composite with an aqueous hydrogen peroxide solution; pre-treating the pre-impregnated thermoset resin composite in an aqueous formic acid solution; and A step of subjecting the pretreated thermosetting resin composite material to the main treatment by placing it in an aqueous hydrogen peroxide solution to which a radical initiator is added.

4. The method for decomposing a thermosetting resin composite material according to claim 3, comprising:

10. The method for decomposing a thermosetting resin composite material according to claim 3, wherein the pre-impregnation is carried out at room temperature and atmospheric pressure for 6 to 17 hours.

11. 2. The method for decomposing a thermosetting resin composite material according to claim 1, wherein the pretreatment is carried out at atmospheric pressure and at a temperature of 80 to 95° C. for 2 to 6 hours.

12. 2. The method for decomposing a thermosetting resin composite material according to claim 1, wherein the main treatment is carried out at atmospheric pressure and at a temperature of 80 to 95° C. for 1 to 3 hours.

13. The concentration of formic acid in the formic acid aqueous solution is 50 to 90%, 2. The method for decomposing a thermosetting resin composite material according to claim 1, wherein the concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution is 30 to 50%.

14. 3. The thermosetting resin composite material according to claim 2, wherein the radical initiator is added so that the radical initiator is present in the formic acid aqueous solution or the hydrogen peroxide aqueous solution at a concentration of 0.1 to 2 wt %. How to disassemble.

15. The method for decomposing a thermosetting resin composite material according to claim 2 , wherein the decomposition method achieves a decomposition rate of 98% or more as determined by thermogravimetric analysis (TGA).

16. The method for decomposing a thermosetting resin composite material according to claim 1 , wherein the decomposition characteristics are adjusted by adding a buffer solution in the pretreatment or main treatment step.

17. a pre-impregnation bath for pre-impregnating the thermosetting resin composite with a formic acid solution or an aqueous hydrogen peroxide solution; a pre-treatment tank connected to the pre-impregnation tank, the pre-treatment tank containing an aqueous formic acid solution or an aqueous hydrogen peroxide solution, to which the thermosetting resin composite material obtained from the pre-impregnation tank is transferred; and a main treatment tank connected to the pretreatment tank, the main treatment tank containing an aqueous hydrogen peroxide solution or an aqueous formic acid solution, to which the thermosetting resin composite material obtained from the pretreatment tank is transferred; and The apparatus used in the method for decomposing a thermosetting resin composite material according to any one of claims 1 to 16, wherein the aqueous solution contained in the pretreatment tank and the aqueous solution contained in the main treatment tank are different from each other.

18. A disassembly kit for a thermosetting resin composite material, comprising: a pre-impregnation composition for pre-impregnation, comprising a formic acid solution or a hydrogen peroxide solution; a pretreatment composition for pretreatment, the pretreatment composition comprising an aqueous formic acid solution or an aqueous hydrogen peroxide solution; and The treatment composition for the treatment includes an aqueous hydrogen peroxide solution or an aqueous formic acid solution. and A kit utilized in the method for decomposing a thermosetting resin composite material according to any one of claims 1 to 16, wherein the aqueous solution contained in the pretreatment composition and the aqueous solution contained in the main treatment composition are different from each other.

19. The decomposition kit for thermosetting resin composite materials according to claim 18, further comprising a radical initiator for addition to the aqueous hydrogen peroxide solution or the aqueous formic acid solution.

20. The kit for decomposing thermosetting resin composite materials according to claim 19, comprising a radical initiator added to the aqueous hydrogen peroxide solution or the aqueous formic acid solution in a concentration of 0.1 to 2 wt % or less.

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