Method for recycling and recovering reinforcement material from reinforced composite material

Abstract

To provide a method for recycling and recovering a reinforcement material from a reinforced composite material capable of recycling a reinforcement material in a continuous fiber state from a reinforced composite material regardless of the kind of base material.SOLUTION: A method for recycling and recovering a reinforcement material from a reinforced composite material is a method for recycling and recovering a reinforcement material from a reinforced composite material containing a base material and the reinforcement material and includes a) a step for decomposing the reinforced composite material into the base material and the reinforcement material with a processing solution and c) a step for winding the reinforcement material around a core material. The processing solution does not contain a solvent of a ketone base, alcohol base, amide base, ether base, and hydrocarbon base.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for recovering reinforcement from reinforced composite materials. [Background technology]

[0002] Reinforced composite materials are materials formed by compounding a base resin with reinforcing materials such as carbon fiber, glass fiber, metal fiber, and high-strength organic fibers. They are characterized by their high strength and lighter weight than metals such as steel. Taking advantage of these characteristics, they are beginning to be used in wind turbine blades as well as some automobiles and aircraft as well as other applications, as a material that contributes significantly to improving energy efficiency. The production volume of carbon fiber, one of the reinforcing materials, is expected to more than double in five years, from 60,000 tons in 2015 to 140,000 tons in 2020. Carbon fiber is first synthesized from petroleum to produce acrylic fiber, which is then turned into threads. It is then carbonized at high temperatures of several thousand degrees Celsius to produce carbon fiber. While carbon fiber can be used as is, it is often processed into various forms, such as continuous fiber, nonwoven fabric, and chopped fiber. It is then compounded with various types of resins to form carbon fiber-reinforced plastics (CFRP), a type of reinforced composite material.

[0003] Carbon fiber reinforced plastics have excellent material properties, such as being strong, hard, rust-resistant, and rot-resistant, but these same properties make disposal a challenge. While ordinary plastics can be easily burned, carbon fiber is difficult to burn due to its highly graphitized structure. Therefore, in Japan, carbon fiber reinforced plastic scraps and waste are crushed and disposed of in landfills as industrial waste. Crushed carbon fiber disposed of in landfills is not biodegradable and becomes a cause of marine plastic pollution.

[0004] Therefore, a method has been proposed in which the reinforcement material is separated and recovered from the used reinforced composite material for reuse. For example, one method involves treating carbon fiber reinforced plastics at high temperatures of 500 to 700°C in a low-oxygen environment, thereby pyrolyzing the resin component that is the base material and recovering only the carbon fibers. A technology known as the two-stage pyrolysis method has also been developed. In this technology, the resin component is pyrolyzed to a certain extent in the first stage, and combustible gas is recovered from it. This gas is then used as combustion gas for heating, reducing fuel consumption. Then, in the second stage, pyrolysis is carried out again, and the resin component remaining on the fiber surface is pyrolyzed and removed (see, for example, Patent Document 1).

[0005] A method using superheated steam has also been proposed. Superheated steam is steam that has a steam temperature above the saturation temperature at a certain pressure, achieved by further superheating saturated steam. This method uses this superheated steam to efficiently pyrolyze the resin component that is the base material and recover only the carbon fiber (see, for example, Patent Document 2).

[0006] Another method has been proposed, in which the resin component is dissolved in a specific organic solvent. This method is characterized by the low treatment temperature of 100 to 150°C and the fact that no resin remains because it is a wet process, so the strength of the recovered carbon fiber is not reduced (see, for example, Non-Patent Document 1).

[0007] Furthermore, a method has been proposed in which methanol is placed in a high-pressure device at 8 MPa or higher to create a supercritical state and dissolve the resin. This method also has the advantage that the strength of the recovered carbon fiber is not reduced because the processing temperature is relatively low at around 240°C (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5347056 [Patent Document 2] Patent No. 5876968 Publication [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-203826 [Non-patent literature]

[0009] [Non-Patent Document 1] Hitachi Chemical Technical Report No. 42 (2004.1) Summary of the Invention [Problem to be solved by the invention]

[0010] In reality, carbon fiber reinforced plastics are mostly utilized as reinforced composite materials, where continuous fibers are processed into intermediate substrates such as prepregs or woven fabrics, which are then combined with a base material such as a thermosetting or thermoplastic resin. However, in the methods described in Patent Documents 1-3, recycled reinforcements are often recovered as long fibers with fiber lengths of several centimeters or short fibers with fiber lengths of several millimeters, limiting their application. The atmospheric dissolution method proposed in Non-Patent Document 1 is limited to dissolving polyester resins such as PET, thereby limiting the carbon fiber reinforced plastics that can be processed. Carbon fiber reinforced plastics using thermoplastic resins are available in a wide variety of resins, including PET (polyester), PP (polypropylene), PEEK (polyether ether ketone), and PA (polyamide). However, distinguishing them at a glance is difficult. While analysis is possible using specialized equipment, it is not practical to analyze and sort each recovered carbon fiber reinforced plastic component. Therefore, if it could be applied to all fiber-reinforced plastics and the reinforcing material could be recycled as continuous fiber, its uses would be greatly expanded, and recycled reinforcing material would not be left over, leading to the realization of a circular society. Examples of components in which reinforcing materials can be recycled into continuous fibers include hydrogen tanks and CNG pressure tanks. These pressure tanks are made of carbon fiber reinforced plastic and have their outer periphery covered with glass fiber reinforced plastic to improve impact resistance and abrasion resistance and to provide electrical insulation from the outside. Aluminum is also often used in the valves and inside the tank. There is a need for technology that can be applied to such components and that can regenerate the reinforcing material in a continuous fiber state.

[0011] The above-mentioned conventional techniques have the following problems. When the pyrolysis method proposed in Patent Document 1 is applied to structural materials composed of carbon fiber-reinforced plastic and glass fiber-reinforced plastic, the glass fibers and aluminum melt and become a paste, making it impossible to separate and recover the reinforcement from the reinforced composite material. Furthermore, Patent Document 1 has the issue of the toxicity of the pyrolysis gas from the resin due to the pyrolysis. Epoxy resin, the main resin in thermosetting carbon fiber-reinforced plastic, produces bisphenol A, a suspected carcinogen, upon pyrolysis, so caution is required. Another problem is that the strength of the recovered carbon fiber decreases by 70 to 80%. This is because high-temperature treatment causes microcracks to form on the carbon fiber surface. Furthermore, when carbon fiber is composited with resin to produce carbon fiber-reinforced plastic, the fiber must be surface-treated to increase its affinity with the resin. Carbon fiber recovered by pyrolysis inhibits surface treatment due to the cracks and resin residue on the surface. Therefore, when carbon fiber-reinforced plastic is produced using carbon fiber recovered by pyrolysis, in addition to the decrease in strength of the carbon fiber itself, a further decrease of 70 to 80% occurs.

[0012] When the superheated steam method proposed in Patent Document 2 is applied to structural materials composed of carbon fiber reinforced plastics and glass fiber reinforced plastics, the glass fibers and aluminum melt and become a paste, as in the aforementioned pyrolysis method, making it impossible to separate and recover the reinforcement from the reinforced composite material. Furthermore, as in the aforementioned pyrolysis method, the high-temperature treatment reduces the strength of the recovered carbon fiber. Furthermore, a rotary kiln is used to improve pyrolysis efficiency, but the carbon fiber reinforced plastic must be pulverized to a size that can fit into the device. As a result, continuous fiber carbon fiber cannot be recovered, and the reinforcement can only be processed into certain shapes, such as nonwoven fabrics and fillers, when it is processed into an intermediate substrate for recombination with the matrix. This limits the uses of the reprocessed reinforced composite material.

[0013] The atmospheric pressure dissolution method proposed in Non-Patent Document 1 is limited to dissolving polyester resins such as PET, which limits the carbon fiber reinforced plastics that can be processed. Carbon fiber reinforced plastics made with thermoplastic resins are made with a wide variety of resins, including PET (polyester), PP (polypropylene), PEEK (polyether ether ketone), and PA (polyamide). However, it is difficult to distinguish between them at a glance. While analysis is possible using specialized equipment, it is not practical to analyze and sort each recovered carbon fiber reinforced plastic part.

[0014] The supercritical method proposed in Patent Document 3 requires a high-pressure device at a very high cost and is difficult to manufacture on a large scale. It is difficult to model and is not practical. As described above, the conventional methods for separating and recovering reinforcement from reinforced composite materials are limited in the types of reinforced composite materials that can be processed, or in that the recovered reinforcement is subject to a decrease in strength or a change in shape due to pulverization, which limits the methods for recombining the reinforcement and the uses of the reinforced composite material when it is reused. Furthermore, depending on the combination of structural materials to be processed, there are cases where the reinforcement cannot be separated and recovered.

[0015] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method for recycling and recovering reinforcement from reinforced composite materials, which can regenerate reinforcement in the form of continuous fibers from reinforced composite materials regardless of the type of base material. [Means for solving the problem]

[0016] As a result of extensive research into solving the above problems, the present inventors have discovered that the above object can be achieved by a method for recycling and recovering reinforcement from a specific reinforced composite material, and have thus completed the present invention.

[0017] That is, the present invention is as follows. [1] A method for recovering and recycling a reinforcement material from a reinforced composite material including a matrix and a reinforcement material, comprising: a) decomposing the reinforced composite material into a matrix and a reinforcement material using a treatment solution; c) winding the reinforcement material onto the core material; Including, A method for recovering and recycling reinforcement from a reinforced composite material, characterized in that the treatment solution does not contain ketone-based, alcohol-based, amide-based, ether-based, or hydrocarbon-based solvents. [2] The step a) a1) a step of obtaining a treatment solution containing oxidizing active species by electrolyzing a sulfuric acid solution; a2) A method for regenerating and recovering a reinforcement material from a reinforced composite material according to [1], comprising the step of immersing the reinforced composite material in the treatment solution to decompose the reinforced composite material into a matrix and a reinforcement material. [3] Between the step a) and the step c) b) washing and drying the reinforcement; A method for recycling and recovering a reinforcement from the reinforced composite material according to [1] or [2], comprising: [4] [4] A method for recycling and recovering a reinforcing material from a reinforced composite material according to any one of [1] to [3], wherein the reinforcing material is composed of at least one type selected from the group consisting of carbon fiber, glass fiber, and metal fiber. [5] A method for producing a reinforced composite material, characterized by combining a reinforcing material recycled and recovered by the method according to any one of [1] to [4] with a base material. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a method for recovering and recycling a reinforcement from a reinforced composite material, which can recover the reinforcement in the form of continuous fibers. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing a method for recycling and recovering reinforcement from the reinforced composite material of this embodiment. FIG. [Figure 2] FIG. 1 is a schematic diagram of a reinforced composite material used in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following description, and various modifications can be made within the scope of the gist of the present invention. First, the reinforced composite material used in the regenerating and recovering method for a reinforcement material according to this embodiment will be described.

[0021] The method for recycling and recovering a reinforcement material from a reinforced composite material of this embodiment is a method for recycling and recovering a reinforcement material from a reinforced composite material containing a base material and a reinforcement material, a) decomposing the reinforced composite material into a matrix and a reinforcement material using a treatment solution; c) winding the reinforcement material onto the core material; The processing solution preferably does not contain ketone-based, alcohol-based, amide-based, ether-based, or hydrocarbon-based solvents. In this specification, the process of decomposing the matrix and the reinforcing material is a process of separating the matrix and the reinforcing material, and may be referred to as a "decomposition process." Also, the process of winding the reinforcing material around the core material may be referred to as a "winding process." 1 is an explanatory diagram showing a method for recycling and recovering reinforcement from a reinforced composite material according to the present embodiment. In a decomposition step, the reinforced composite material is decomposed into a matrix and a reinforcement, and in a winding step, the reinforcement recovered in the decomposition step is wound around a core material.

[0022] [Reinforced composite material] The reinforced composite material is a material whose strength is improved by combining a reinforcing material of a different material, such as fiber, with a matrix material such as a resin. The method of combining is not particularly limited, and may be a method that utilizes interactions such as hydrogen bonding or intermolecular forces, or may be dispersion, adhesion, bonding, adsorption, support, arrangement, etc. The reinforced composite material may be a material obtained by molding (e.g., injection molding, compression molding, etc.) a raw material containing a matrix material (e.g., a resin described below) and a reinforcing material. For example, it may be a laminate in which multiple reinforced composite materials are laminated directly or via another layer such as an adhesive layer. The reinforced composite material may include a matrix, a reinforcement, other additives, and the like.

[0023] [Reinforcement material] The reinforcing material is a material that is compounded or dispersed in the matrix resin that is the base material of the reinforced composite material, and examples thereof include carbon fiber, glass fiber, and metal fiber. The above-mentioned reinforcing materials can be used alone or in combination of two or more.

[0024] Carbon fiber is a fiber made by carbonizing acrylic fiber or pitch (a by-product of petroleum, coal, coal tar, etc.) at high temperatures. Glass fiber is made by melting and drawing glass into fibers. Metal fibers are made by processing metals such as stainless steel, aluminum, iron, nickel, and copper into threads using plastic processing (rolling, etc.), melt spinning, CVD, etc.

[0025] These fibers are processed into intermediate substrates such as continuous fibers or nonwoven fabrics, and then combined with the base material. Continuous fibers are long fibers used in unidirectional layers where all the fibers are parallel to each other, and can be knitted or woven. Unidirectional layers can also be stacked in various directions to create quasi-isotropic, orthotropic, and anisotropic plates. Nonwoven fabrics are sheets of intertwined fibers that are not woven. Nonwoven fabrics are fabrics made by bonding or intertwining fibers through thermal, mechanical, or chemical action.

[0026] The content of the reinforcing material in the reinforced composite material is preferably 10 to 80% by mass, with the reinforced composite material being 100% by mass, with the lower limit preferably being 15% by mass or more, or 20% by mass or more, and the upper limit preferably being 75% by mass or less, or 70% by mass or less.

[0027] [Base material] The base material is a resin used as a matrix of the reinforced composite material, and a thermoplastic resin or a thermosetting resin is used. The above base materials can be used alone or in combination of two or more.

[0028] Thermoplastic resins are resins that become soft when heated to their glass transition temperature or melting point and can be molded into the desired shape. Generally, thermoplastic resins are difficult to machine, such as by cutting or grinding, so they are commonly processed using injection molding, in which they are heated and softened, then forced into a mold, cooled, and solidified to produce the final product. Examples include polyethylene, polypropylene, polystyrene, ABS resin, polyvinyl chloride resin, methyl methacrylate resin, nylon, fluororesin, polycarbonate, and polyester resin.

[0029] Thermosetting resins are resins that polymerize when heated, forming a polymer network structure, hardening and becoming irreversible. To use, a relatively low molecular weight resin with a fluidity level is formed into a desired shape, and then heated to cause a reaction and hardening. There are types of adhesives and putties that use a mixture of liquid A (base) and liquid B (hardener), but these are epoxy resins, which are thermosetting resins, and a polymerization reaction occurs when they are mixed. Thermosetting resins are hard and resistant to heat and solvents. Examples include phenolic resin, epoxy resin, unsaturated polyester resin, and polyurethane.

[0030] The content of the base material in the reinforced composite material is preferably 20 to 90 parts by mass, based on 100 parts by mass of the reinforcing material, with the lower limit preferably being 25 parts by mass or more, or 30 parts by mass or more, and the upper limit preferably being 85 parts by mass or less, or 80 parts by mass or less.

[0031] [Other additives] The other additives are not particularly limited, and examples thereof include flame retardants, heat stabilizers, antioxidants, light absorbers, release agents, lubricants, various stabilizers, antistatic agents, dyes and pigments, and various reactants used in the above-mentioned compounding. The content of the other additives in the reinforced composite material may be 0.01% by mass or more and 80% by mass or less, with the reinforced composite material being 100% by mass.

[0032] [Structural material] A structural material is a material that is constructed by bonding a different resin material or a different reinforced composite material to a reinforced composite material containing a base material and a reinforcement material. An example of the structure is shown in Figure 2. For example, hydrogen tanks are made of carbon fiber reinforced plastic and have their outer periphery covered with glass fiber reinforced plastic to improve impact resistance and scratch resistance and to provide electrical insulation from the outside. Aluminum is also often used for the valves and inside the tank.

[0033] (decomposition process) The decomposition step is preferably carried out using a treatment solution, more preferably using an electrolytic sulfuric acid method. The decomposition step may be carried out while heating, pressurizing, or the like.

[0034] The treatment solution does not contain ketone, alcohol, amide, ether, or hydrocarbon solvents. The treatment solution may contain a sulfuric acid-based solvent, which allows for more efficient recovery of the reinforcing material in the form of continuous fibers, regardless of the type of base material. Examples of the sulfuric acid-based solvent include a mixed solvent of sulfuric acid and hydrogen peroxide (for example, a mixed solvent in which the mass ratio of sulfuric acid to hydrogen peroxide is 3 / 1 to 7 / 1), a solution obtained by an electrolytic sulfuric acid method, etc. Among these, a solution obtained by an electrolytic sulfuric acid method is preferred, as it can be used without adding other solvents such as hydrogen peroxide, the sulfuric acid can be reused, and the base material can be decomposed more efficiently. From the viewpoint of more efficiently decomposing the base material, the treatment solution preferably contains 30 to 95 mass % of a sulfuric acid-based solvent, more preferably 50 to 80 mass % of a sulfuric acid-based solvent, relative to 100 mass % of the treatment solution. The treatment solution may also be a solution consisting of a sulfuric acid-based solvent and water. The treatment solution may consist solely of a sulfuric acid-based solvent, or may contain hydrochloric acid, nitric acid, hydrogen peroxide, or a peroxide such as peroxosulfuric acid.

[0035] The electrolytic sulfuric acid method is a method in which a reinforced composite material consisting of a base material and a reinforcing material is immersed in a treatment solution containing oxidizing active species obtained by electrolyzing a sulfuric acid solution, whereby the base material is decomposed into water, carbon dioxide, etc., and the decomposition products are dissolved in the treatment solution, and then the reinforcing material is extracted from the treatment solution. In particular, the electrolytic sulfuric acid method is preferred from the viewpoint of further suppressing decomposition of the reinforcing material and enabling the reinforcing material to be recovered with a length closer to the average fiber length of the reinforcing material contained in the reinforced composite material before recovery.

[0036] The oxidizing active species are generated by electrolyzing a sulfuric acid solution at a predetermined current and a predetermined voltage, and specifically include hydroxyl radicals, peroxosulfuric acid, peroxodisulfuric acid, and the like.

[0037] Specifically, the regenerating and recovering method for reinforcing materials according to this embodiment includes the following steps: a) a step of decomposing a reinforced composite material consisting of a matrix and a reinforcing material into the matrix and the reinforcing material using a treatment solution; c) winding the reinforcement material onto the core material; Includes.

[0038] The sulfuric acid solution is a solution composed of sulfuric acid (H2SO4) and water (H2O). The concentration of sulfuric acid contained in the sulfuric acid solution is preferably 30 to 95 mass%, more preferably 50 to 80 mass%. If the sulfuric acid concentration is less than 30 mass%, the amount of oxidizing active species required to decompose the base material of the reinforced composite material cannot be obtained, and it takes a long time to decompose the base material. Note that even with concentrated sulfuric acid with a concentration of over 95%, such as 98 mass%, it is possible to generate oxidizing active species by simply devising an electrolysis method, but this is not preferred because the amount of oxidizing active species generated is extremely low due to the difficulty in flowing current during electrolysis and the life of the electrodes used for electrolysis is extremely shortened.

[0039] Concentrated sulfuric acid, hydrochloric acid, or nitric acid may be added to the treatment solution containing the electrolyzed oxidizing active species. Furthermore, peroxides such as hydrogen peroxide and peroxosulfuric acid may be added to the treatment solution. In this case, the decomposition rate of the matrix of the reinforced composite material can be increased.

[0040] For the electrolysis of sulfuric acid solution, platinum electrodes, carbon electrodes, etc. can be used, but for the electrolysis of highly concentrated sulfuric acid solution, so-called diamond electrodes, in which the surface of a metal plate is coated with a thin film of diamond, can be used from the viewpoint of durability. As an electrolysis device for sulfuric acid solution, it is preferable to use a diaphragm-type electrolysis cell using diamond electrodes.

[0041] The electrolysis conditions (for example, the conditions for using a diamond electrode) are current density of 0.01 to 10 A / cm 2 (Preferably 1 to 10 A / cm 2 ) and a voltage of 0.1 to 300 V (preferably 100 to 200 V), but these may be changed as appropriate depending on the type of electrode, the sulfuric acid concentration of the sulfuric acid solution, the amount of the sulfuric acid solution, etc.

[0042] The electrolysis is preferably carried out in a closed system, preferably in a closed sulfuric acid solution circulation system, while circulating a predetermined amount of sulfuric acid solution. The circulation method may be a method of passing the solution parallel to the electrode surface at a flow rate of 50 mL / min or more using a pump or the like, or a method of natural circulation by convection with the flow of gas generated by electrolysis.

[0043] The electrolysis treatment time may be varied as appropriate depending on the amount of sulfuric acid solution, sulfuric acid concentration, flow rate of the sulfuric acid solution, current flow conditions, etc., but treatment for 0.5 to 10 hours per 1 L of sulfuric acid solution is preferred in terms of efficiently generating oxidizing active species.

[0044] In the case of a sulfuric acid electrolysis method in which electrolysis is performed using sulfuric acid solutions as the catholyte and the anolyte, sulfuric acid solutions of different concentrations may be used for both electrodes. In particular, in this embodiment, a sulfuric acid solution containing oxidizing active species obtained by electrolyzing high-concentration sulfuric acid is effective in promoting the decomposition of the base material of the reinforced composite material, so it is preferable to increase the sulfuric acid concentration on the anode side and decrease the sulfuric acid concentration on the cathode side in order to extend the life of the electrodes.

[0045] Electricity can be procured from various devices as a power source for electrolyzing the sulfuric acid solution, but it is preferable to use electricity generated from so-called renewable energy sources such as solar cells. In addition, the hydrogen (generated from the cathode) and oxygen (generated from the anode) generated by electrolysis can be collected and converted into electricity or heat.

[0046] The sulfuric acid solution containing the obtained oxidizing active species can be supplied to a treatment tank for decomposing the base material of the reinforced composite material by either a continuous method in which the solution is continuously supplied from an electrolytic device to the treatment tank using a pump or the like, or a batch method in which the sulfuric acid solution is circulated in a closed system, and the treatment solution is collected from the system after electrolysis and supplied to the treatment tank. The collected treatment solution may also be combined with a device that can heat, cool, or pressurize it.

[0047] The treatment solution used to treat the reinforced composite material can be reused, and can be recovered, adjusted in concentration, and reused as a sulfuric acid solution for electrolysis to generate oxidizing active species again.

[0048] The treatment solution containing the oxidizing active species is preferably heated to enhance the decomposition of the matrix of the reinforced composite material. The heating temperature depends on the boiling point of the treatment solution, but it is preferable to heat the solution to a temperature of 100°C or higher in order to efficiently decompose the matrix of the reinforced composite material in a short period of time. The heating temperature may be a temperature below the boiling point of the sulfuric acid solution, and the solution is heated at atmospheric pressure or under an inert gas atmosphere. The treatment solution may be heated under increased or reduced pressure.

[0049] The treatment solution is preferably used in a proportion of 0.05 to 50 L, more preferably 0.1 to 10 L, per 1 kg of reinforced composite material, from the viewpoint of more efficiently decomposing the base material and the reinforcing material and making it easier to obtain the reinforcing material in a continuous fiber state. In addition, from the viewpoint of making it easier to obtain a reinforcing material in a continuous fiber state, it is preferable that the reinforced composite material used in the decomposition step is not subjected to pretreatment such as cutting. When the reinforced composite material is a laminate, the treatment may be carried out in multiple separate stages for each layer. The treatment solution used in each stage may be the same or different. The treatment conditions for each stage may be the same or different. The reinforcement may be wound up after each stage, or may be wound up all at once after all layers have been treated.

[0050] (winding process) In order to recover the reinforcement of reinforced composite materials as continuous fibers, the matrix is ​​decomposed to extract a portion of the reinforcement, which is then tied to a core, and the matrix is ​​further decomposed while the reinforcement is wound up, allowing for recycling.

[0051] At this time, the reinforcing material may be washed with water or dried. The reinforcing material may be washed with water or dried before being wound up, or may be washed with water or dried after being wound up. A step of washing and drying the reinforcing material may be provided between the disassembly step and the winding step.

[0052] (Reinforced materials, intermediate base materials, reinforced composite materials) Details of the reinforcement material, intermediate substrate, and reinforced composite material produced using the method for recycling and recovering a reinforcement material according to the present embodiment will be described below.

[0053] When regenerated using the regenerating and recovering method for reinforcing materials of the present embodiment described above, it is preferable that the strength of the regenerated reinforcing material is 80% or more of the strength of the reinforcing material before regeneration, and that the shape retention rate of the reinforcing material before and after regeneration is 90% or more. Furthermore, when regenerated using the regenerating and recovering method for reinforcing materials of the present embodiment described above, it is preferable that the strength of the regenerated reinforcing material is 90% or more of the strength of the reinforcing material before regeneration, and that the shape retention rate of the reinforcing material before and after regeneration is 80% or more. The strength of the reinforcing material is measured by the method described in the Examples below, and the shape retention rate before and after recycling is measured by the method described in the Examples below.

[0054] Furthermore, when regenerated using the regenerating and recovering method for reinforcing materials of this embodiment described above, it is more preferable that the strength of the regenerated reinforcing material is 90% or more of the strength of the reinforcing material before regeneration, and that the shape retention rate of the reinforcing material before and after regeneration is 90% or more.

[0055] The reinforcing material recycled by the method for recycling and recovering a reinforcing material according to the present embodiment may be processed appropriately to produce an intermediate substrate, which may be a prepreg, woven fabric, nonwoven fabric, laminate, or pellet made of continuous fibers containing the recycled reinforcing material.

[0056] A recycled reinforced composite material may be produced by compounding the above-mentioned recycled reinforcing material and the above-mentioned intermediate substrate in a matrix material such as a resin.

[0057] In this embodiment, when a reinforced composite material is recycled using the above-mentioned method, the strength of the reinforced composite material recycled using the recycled reinforcement is preferably 65% ​​or more, more preferably 70% or more, and even more preferably 75% or more, of the strength of the reinforced composite material produced using the reinforcement before recycling, and is preferably 95% or less, more preferably 80% or less. The strength of the reinforced composite material is measured by the method described in the examples below.

[0058] When regenerated using the reinforcing material regeneration and recovery method of the present embodiment described above, the average fiber length of the regenerated and recovered reinforcing material is preferably 50% or more, and more preferably 80% or more, of the average fiber length of the reinforcing material contained in the reinforced composite material before regeneration and recovery (100%).

[0059] (Method of manufacturing reinforced composite materials) The method for producing a reinforced composite material of this embodiment is a method for producing the reinforced composite material by combining a base material with a reinforcing material recovered by the method for recycling and recovering a reinforcing material of this embodiment described above. The base material may be a new base material. The method for producing the reinforced composite material includes, for example, a) a step of decomposing a reinforced composite material consisting of a matrix and a reinforcing material into the matrix and the reinforcing material using a treatment solution; c) winding the reinforcement material onto the core material; Includes.

[0060] (Methods for realizing a recycling-oriented society using reinforced composite materials) A method for realizing a recycling-oriented society for reinforced composite materials is to use the method for processing reinforced composite materials of this embodiment described above. The reinforced composite material before recycling may be a material for transportation equipment, construction materials, electronic parts, etc., and for example, a reinforced composite material contained in at least one transportation equipment selected from the group consisting of aircraft, automobiles, spacecraft, ships, and trains may be used, and the recycled reinforced composite material may be used again in the transportation equipment. [Example]

[0061] The present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

[0062] In the examples and comparative examples, measurements and evaluations were carried out by the following methods.

[0063] <Strength ratio of reinforcement material> The strength of the reinforcing material was measured by the following method. The strength in the longitudinal direction was measured at 23°C and a tensile speed of 1.5 mm / min using a universal tensile tester (EZ TEST-5N manufactured by Shimadzu Corporation). The strength was calculated as the average of 80 randomly selected reinforcing materials. The strength ratio (%) of the reinforcement material was calculated using the following formula. Strength ratio of reinforcement (%) = 100 × (strength of reinforcement recycled from reinforced composite material / strength of reinforcement contained in reinforced composite material before recycling)

[0064] <Shape retention rate> The shape retention rate was calculated by measuring the diameter of the reinforcing material using a scanning probe microscope (SPM-9700 manufactured by Shimadzu Corporation) and calculating the ratio of the diameter before and after regeneration. The diameter of the reinforcement in the width direction was measured, and the average diameter of 10 randomly selected reinforcements was used. The shape retention rate (%) was calculated using the following formula. Shape retention rate (%) = 100 x (diameter of reinforcement recycled from reinforced composite material / diameter of reinforcement contained in reinforced composite material before recycling)

[0065] [Example 1] The reinforced composite material used for recycling was a hydrogen tank with the structure shown in Figure 2. The hydrogen tank is a laminate in which the reinforcement A1 of the outer reinforced composite material is glass fiber: RS440 RR-520 (manufactured by Nitto Boseki Co., Ltd.), and the reinforcement A2 of the inner reinforced composite material is carbon fiber: Torayca T700SC-12K-50C (manufactured by Toray Industries, Inc.). The two reinforced composite materials were each produced using a filament winder (manufactured by Asahi Kasei Engineering Corporation) with epoxy resin as the base material, and then cured at 150°C for 30 minutes to produce hydrogen tanks. The reinforcing material was recovered from the reinforced composite material using an electrolytic sulfuric acid method. Specifically, the electrode area is 700 cm 2 A treatment solution containing oxidizing active species was produced by electrolyzing a 60% sulfuric acid aqueous solution in a diaphragm-type electrolytic cell using a diamond electrode while the electrode was water-cooled. The amount of treatment solution (sulfuric acid aqueous solution) electrolyzed at one time was 10 L. The current was 3-10 A / cm. 2 The voltage was 170-200V and the treatment time was 120 minutes. The electric field was applied in a closed system, with the gas generated by electrolysis being retained and allowed to circulate naturally. One hydrogen tank (120 kg) was immersed in 60 L of the prepared treatment solution containing active oxidizing species. In the first step, the external reinforced composite material was immersed at 150°C for 5 hours, the base material of the external reinforced composite material was decomposed, and reinforcement A1 was wound around a core as continuous fiber, washed with water, dried, and separated and recovered. Then, in the second step, the internal reinforced composite material was immersed at 150°C for 5 hours to decompose the matrix of the internal reinforced composite material. The separated reinforcement A2 was wound as continuous fiber on a core, washed with water, and dried. The strength ratio of Reinforcement A1 after winding was 90% or more, and the strength ratio of Reinforcement A2 after winding was 90% or more. After winding, the shape retention rate of Reinforcement A1 was 90% or more, and the shape retention rate of Reinforcement A2 after winding was 90% or more. The average fiber length of reinforcement A1 after winding was 90% of the average fiber length of reinforcement A1 contained in the reinforced composite material before recycling (100%). The average fiber length of reinforcement A2 after winding was 90% of the average fiber length of reinforcement A2 contained in the reinforced composite material before recycling (100%). Both reinforcements A1 and A2 could be recycled and recovered in a continuous fiber state. The average fiber length was calculated as the average of the lengths in the extension direction of 80 randomly selected reinforcements.

[0066] [Example 2] The matrix of the reinforced composite material was disassembled in the same manner as in Example 1. The separated reinforcement A2 was washed with water, dried, and then wound around a core to regenerate the continuous fiber reinforcements A1 and A2. The strength ratios of the recycled reinforcements A1 and A2 were above 90%. The shape retention rates of the recycled reinforcements A1 and A2 were over 90%. The average fiber length of reinforcements A1 and A2 after winding was 90% of the average fiber length of the reinforcements contained in the reinforced composite material before recycling, which was 100%, and they could be recycled and recovered in the form of continuous fibers.

[0067] [Example 3] The reinforced composite material used for recycling was a hydrogen tank with the structure shown in Figure 2. The hydrogen tank is a laminate in which the reinforcement A1 of the outer reinforced composite material is glass fiber: RS440 RR-520 (manufactured by Nitto Boseki Co., Ltd.), and the reinforcement A2 of the inner reinforced composite material is carbon fiber: Torayca T700SC-12K-50C (manufactured by Toray Industries, Inc.). The two reinforced composite materials mentioned above were each produced using a filament winder (manufactured by Asahi Kasei Engineering Corporation) and polyamide resin (20 wt% dimethyl sulfoxide solution) as the base material, and then dried at 150°C for 30 minutes to produce a hydrogen tank. The matrix of the reinforced composite material of the obtained hydrogen tank was disassembled in the same manner as in Example 1. The separated reinforcement A2 was washed with water, dried, and then wound around a core to regenerate continuous fiber reinforcements A1 and A2. The strength ratios of the recycled reinforcements A1 and A2 were above 90%. The shape retention rates of the recycled reinforcements A1 and A2 were over 90%. The average fiber length of reinforcements A1 and A2 after winding was 90% of the average fiber length of the reinforcements contained in the reinforced composite material before recycling, which was 100%, and they could be recycled and recovered in the form of continuous fibers.

[0068] [Example 4] The reinforced composite material used for recycling was a hydrogen tank with the structure shown in Figure 2. The hydrogen tank is a laminate in which the reinforcement A1 of the outer reinforced composite material is glass fiber: RS440 RR-520 (manufactured by Nitto Boseki Co., Ltd.), and the reinforcement A2 of the inner reinforced composite material is carbon fiber: Torayca T700SC-12K-50C (manufactured by Toray Industries, Inc.). The two reinforced composite materials were each produced using a filament winder (manufactured by Asahi Kasei Engineering Corporation) with phenolic resin as the base material, and then cured at 200°C for 30 minutes to produce hydrogen tanks. The matrix of the reinforced composite material of the obtained hydrogen tank was disassembled in the same manner as in Example 1. The separated reinforcement A2 was washed with water, dried, and then wound around a core to regenerate continuous fiber reinforcements A1 and A2. The strength ratios of the recycled reinforcements A1 and A2 were above 90%. The shape retention rates of the recycled reinforcements A1 and A2 were over 90%. The average fiber length of reinforcements A1 and A2 after winding was 90% of the average fiber length of the reinforcements contained in the reinforced composite material before recycling, which was 100%, and they could be recycled and recovered in the form of continuous fibers.

[0069] [Example 5] The reinforced composite material used for recycling was a hydrogen tank with the structure shown in Figure 2. The hydrogen tank is a laminate in which the reinforcement A1 of the outer reinforced composite material is glass fiber: RS440 RR-520 (manufactured by Nitto Boseki Co., Ltd.), and the reinforcement A2 of the inner reinforced composite material is carbon fiber: Torayca T700SC-12K-50C (manufactured by Toray Industries, Inc.). The two reinforced composite materials were each produced using a filament winder (manufactured by Asahi Kasei Engineering Corporation) with epoxy resin as the base material, and then cured at 150°C for 30 minutes to produce hydrogen tanks. The regenerating and recovering method of reinforcement from reinforced composite materials was a sulfuric acid / hydrogen peroxide mixture method. Specifically, 60 wt % sulfuric acid was slowly added to hydrogen peroxide water while cooling to below 100°C, so that the sulfuric acid / hydrogen peroxide ratio was 3 / 1. One hydrogen tank (120 kg) was immersed in 60 L of the prepared treatment solution containing active oxidizing species. In the first step, the external reinforced composite material was immersed at 150°C for 15 hours, the base material of the external reinforced composite material was decomposed, and reinforcement A1 was wound around a core as continuous fiber, washed with water, dried, and separated and recovered. Then, in the second step, the internal reinforced composite material was immersed at 150°C for 15 hours to decompose the matrix of the internal reinforced composite material. The separated reinforcement A2 was wound as continuous fiber on a core, washed with water, and dried. The strength ratio of Reinforcement A1 after winding was 90% or more, and the strength ratio of Reinforcement A2 after winding was 90% or more. After winding, the shape retention rate of Reinforcement A1 was 90% or more, and the shape retention rate of Reinforcement A2 after winding was 90% or more. The average fiber length of reinforcement A1 after winding was 90% of the average fiber length of reinforcement A1 contained in the reinforced composite material before recycling (100%). The average fiber length of reinforcement A2 after winding was 90% of the average fiber length of reinforcement A2 contained in the reinforced composite material before recycling (100%). Both reinforcements A1 and A2 could be recycled and recovered in a continuous fiber state. The average fiber length was calculated as the average of the lengths in the extension direction of 80 randomly selected reinforcements.

[0070] [Comparative Example 1] The same hydrogen tank as in Example 1 was used as the reinforced composite material. The reinforcement material was separated and recovered from the reinforced composite material by pyrolysis. Specifically, the produced reinforced composite material was placed in a combustion furnace and treated in a nitrogen atmosphere at 600°C for 5 hours in the first stage to thermally decompose the base material of the external reinforced composite material and attempt to separate and recover reinforcement A1. However, the glass fiber of reinforcement A1 melted and turned into a paste, making it impossible to separate and recover reinforcement A2.

Claims

1. A method for recovering and recycling a reinforcement material from a reinforced composite material including a matrix and a reinforcement material, comprising: a) decomposing the reinforced composite material into a matrix and a reinforcement material by a treatment solution; c) winding the reinforcement material onto the core material; Including, A method for recovering and recycling reinforcement from a reinforced composite material, characterized in that the treatment solution does not contain ketone-based, alcohol-based, amide-based, ether-based, or hydrocarbon-based solvents.

2. The step a) a1) a step of electrolyzing a sulfuric acid solution to obtain a treatment solution containing oxidizing active species; a2) immersing the reinforced composite material in the treatment solution to decompose the reinforced composite material into a matrix and a reinforcement material.

3. Between the step a) and the step c) b) washing and drying the reinforcement; 3. A method for recovering and recycling a reinforcement from the reinforced composite material according to claim 1 or 2, comprising:

4. 4. The method for recovering and recycling a reinforcing material from a reinforced composite material according to claim 1, wherein the reinforcing material is at least one selected from the group consisting of carbon fiber, glass fiber, and metal fiber.

5. A method for producing a reinforced composite material, comprising combining a reinforcing material recycled and recovered by the method according to any one of claims 1 to 4 with a base material.

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