Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
  • B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/26—Drying gases or vapours
  • B01D53/265—Drying gases or vapours by refrigeration (condensation)
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
  • B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/10—Nitrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/12—Oxygen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B2101/00—Type of solid waste
  • B09B2101/75—Plastic waste
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2307/00—Use of elements other than metals as reinforcement
  • B29K2307/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/16—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with inorganic material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to a method for processing composite materials, gases, and a recycling system.
• Composite reinforced materials are materials that are molded by combining a base material resin with reinforcing materials such as carbon fiber, glass fiber, metal fiber, high-strength organic fiber, inorganic filler, metal filler, carbon nanotubes, and cellulose nanofiber. They are characterized by their high strength and light weight compared to metals such as iron. Taking advantage of these characteristics, composite materials are beginning to be used in wind turbine blades as well as some automobiles and aircraft as a material that greatly contributes to improving energy efficiency.
• carbon fiber the reinforcing material in carbon fiber reinforced plastics
• Carbon fiber is first produced by synthesizing a chemical substance called acrylonitrile from petroleum, which is then spun into acrylic fiber. Carbon fiber is then produced by carbonizing it at high temperatures of several thousand degrees.
• the carbon fiber produced can be used as is, but most of it is processed into various forms such as continuous fiber, nonwoven fabric, and chopped, and is then compounded with various types of resin to be used as carbon fiber reinforced plastic (CFRP), a type of composite material.
• CFRP carbon fiber reinforced plastic
• Carbon fiber reinforced plastics have excellent material properties, such as being strong, hard, rust-free, and rot-resistant. However, because of these excellent material properties, disposal methods have become an issue. Ordinary plastics can be easily burned, but carbon fiber is difficult to burn because of its highly graphitized structure. For this reason, in Japan, scraps and waste materials of carbon fiber reinforced plastics are crushed as industrial waste and disposed of in landfills. Crushed carbon fiber disposed of in landfills is not biodegradable and becomes a cause of marine plastic pollution.
• Superheated steam is steam that has a steam temperature equal to or higher than the saturation temperature at a certain pressure by further heating saturated steam. There is a method using this superheated steam to efficiently pyrolyze the resin component, which is the base material, and recover only the carbon fibers (see, for example, Patent Document 2).
• Non-Patent Document 2 technology has been developed to manufacture resins such as polycarbonate using carbon dioxide as an industrial raw material.
• carbon dioxide As an industrial raw material, it is necessary that the concentration of carbon dioxide in the gas is high.
• Patent Document 1 the recovered carbon fibers are treated under low oxygen conditions to prevent a decrease in strength, but there is a problem in that epoxy resin, which is the main resin in thermosetting carbon fiber reinforced plastics, generates bisphenol A, which is suspected to be a carcinogenic substance, through thermal decomposition. In addition, the carbon dioxide concentration in the gas generated during thermal decomposition is low, making it impossible to use as an industrial raw material. Furthermore, Patent Document 2 has the same problems as Patent Document 1.
• Non-Patent Document 1 dissolves resin in a solvent, so it is not possible to obtain carbon dioxide, an industrial raw material, from the resin, and therefore it cannot be used as an industrial raw material.
• many types of organic matter remain in the solvent after dissolution, and the process of isolating the organic matter that can be used as an industrial raw material from these requires additional energy, making reuse difficult.
• the present invention was made in consideration of the above problems, and aims to provide a method for processing composite materials that not only makes it possible to recover reinforcing materials from reinforced composite materials, but also makes it possible to utilize the carbon dioxide in the gas generated during pyrolysis as an industrial raw material.
• the inventors conducted extensive research to solve the above-mentioned problems regarding a method for treating a composite material, which comprises a step of recovering the reinforcing material by decomposing the resin from the composite material composed of resin and reinforcing material using sulfuric acid and heat.
• a method for treating a composite material which comprises a step of recovering the reinforcing material by decomposing the resin from the composite material composed of resin and reinforcing material using sulfuric acid and heat.
• a method for treating a composite material comprising a step of decomposing the resin from a composite material composed of a resin and a reinforcing material by using sulfuric acid and heat to recover the reinforcing material,
• the method for treating a composite material further comprises a step of recovering gas generated by decomposing the resin, wherein the ratio of carbon dioxide in the recovered gas is 90 mass% or more.
• the method for treating a composite material according to [1] further comprising a step of utilizing the recovered gas as an industrial raw material.
• the method for treating a composite material according to [1] further comprising a step of utilizing the carbon dioxide contained in the recovered gas as an industrial raw material.
• the step of recovering the reinforcing material uses a solution containing an oxidizing active species derived from the sulfuric acid as a decomposition solution, and decomposes the resin by immersing the composite material in the decomposition solution and heating it.
• a reinforcing material of the composite material is a carbon material such as carbon fiber, carbon nanotube or graphene.
• a recycling system including a step of recovering a reinforcing material from a composite material composed of a resin and a reinforcing material by decomposing the resin using sulfuric acid and heat, A recycling system, characterized in that the gas, liquid or solid generated during the decomposition of the resin is reused as an industrial raw material.
• the present invention provides a method for processing composite materials that not only allows the recovery of reinforcing materials from reinforced composite materials, but also allows the carbon dioxide gas generated during decomposition to be utilized as an industrial raw material.
• present embodiment 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 composite material used in the composite material processing method of the present embodiment will be described.
• the composite material of the present embodiment is a material whose strength is improved by compounding a reinforcing material of a different material such as a fiber or a filler in a base material such as a resin.
• the compounding method is not particularly limited, and may be a method that utilizes interactions such as hydrogen bonds or intermolecular forces, and may be dispersion, attachment, adhesion, adsorption, support, arrangement, etc.
• a composite material may include a matrix material, a reinforcing material, other additives, and the like.
• the reinforcing material constituting the composite material of this embodiment is a material that is compounded or dispersed in the matrix resin that is the base material of the composite material, and examples of the reinforcing material include carbon fiber, glass fiber, metal fiber, organic high-strength fiber, inorganic filler, carbon nanotube, cellulose nanofiber, etc., and is preferably a carbon material such as carbon fiber, carbon nanotube, or graphene.
• the reinforcing materials can be fibrous or particulate, and although the definition is not clear, generally, those with a large aspect ratio (length/width) (for example, an aspect ratio of 100 or more, preferably 200 or more) are called fibrous, and those with a small aspect ratio (length/width) (for example, an aspect ratio of less than 200, preferably less than 100) are called particulate.
• the carbon fiber is a fiber made by carbonizing acrylic fiber or pitch (a by-product of petroleum, coal, coal tar, etc.) at high temperatures.
• the glass fiber is formed by melting and drawing glass into fibers.
• the metal fibers are obtained by processing metals such as stainless steel, aluminum, iron, nickel, copper, etc., into thread form by plastic processing (rolling, etc.), melt spinning, CVD, etc.
• the organic high strength fibers are fibers made from resins such as polyamide, polyester, acrylic, polyparaphenylenebenzobisoxazole, and polyimide.
• the continuous fibers are long fibers that are used in the form of 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, or anisotropic plates.
• the nonwoven fabric is a sheet-like material made by intertwining fibers without weaving them, and refers to fabric made by bonding or intertwining fibers through thermal, mechanical or chemical action.
• the elements constituting the inorganic filler include, for example, elements in Groups 1 to 16 of the periodic table. Although there is no particular limitation on these elements, elements in Groups 2 to 14 of the periodic table are preferred. Specific examples include Group 2 elements (Mg, Ca, Ba, etc.), Group 3 elements (La, Ce, Eu, Ac, Th, etc.), Group 4 elements (Ti, Zr, Hf, etc.), Group 5 elements (V, Nb, Ta, etc.), Group 6 elements (Cr, Mo, W, etc.), Group 7 elements (Mn, Re, etc.), Group 8 elements (Fe, Ru, Os, etc.), Group 9 elements (Co, Rh, Ir, etc.), Group 10 elements (Ni, Pd, Pt, etc.), Group 11 elements (Cu, Ag, Au, etc.), Group 12 elements (Zn, Cd, etc.), Group 13 elements (Al, Ga, In, etc.), and Group 14 elements (Si, Ge, Sn, Pb, etc.).
• Inorganic compounds containing these elements include, for example, oxides (including complex oxides), halides (fluorides, chlorides, bromides, iodides), oxoacid salts (nitrates, sulfates, phosphates, borates, perchlorates, carbonates, etc.), compounds formed from the above elements and negative elements such as carbon monoxide, carbon dioxide, and carbon disulfide, as well as salts such as hydrocyanic acid, hydrocyanates, cyanates, thiocyanates, and carbides.
• An inorganic filler may contain one or more of the above elements. Multiple elements may be present uniformly or unevenly in the particle, and the surface of a particle of a compound of one element may be coated with a compound of another element. These inorganic fillers may be used alone or in combination.
• preferred inorganic fillers include, but are not limited to, at least one element selected from the group consisting of silica, zirconia, titanium, zinc, iron, copper, chromium, cadmium, carbon, tungsten, antimony, nickel, and platinum.
• the carbon nanotube is a material in which a six-membered ring network (graphene sheet) made of carbon is arranged in a single or multi-layered coaxial tube shape. It is an allotrope of carbon and is sometimes classified as a type of fullerene.
• the cellulose nanofibers are wood cellulose fibers that have been thinned to a width of about 15 nanometers.
• the content of the reinforcing material in the composite material of this embodiment is preferably 10 to 80 mass %, with the composite material being 100 mass %.
• the content of the reinforcing material is more preferably 15 mass % or more, and even more preferably 20 mass % or more.
• the content of the reinforcing material is more preferably 75 mass % or less, and even more preferably 70 mass % or less.
• the base material constituting the composite material of this embodiment is a resin used as a matrix of the composite material, and a thermoplastic resin or a thermosetting resin is used.
• thermoplastic resin refers to a resin that becomes soft when heated to its glass transition temperature or melting point and can be molded into the desired shape.
• thermoplastic resins are often difficult to machine, such as by cutting or grinding, so injection molding is widely used, in which the resin is heated and softened, then pressed into a mold, cooled, solidified, and made into the final product.
• examples include polyethylene, polypropylene, polystyrene, ABS resin, polyvinyl chloride resin, methyl methacrylate resin, nylon, fluororesin, polycarbonate, polyester resin, etc.
• thermosetting resin refers to a resin that polymerizes when heated, forms a polymer network structure, and hardens and cannot be restored to its original shape.
• a relatively low molecular weight resin with a level of fluidity is shaped into a desired shape, and then reacted and hardened by heating or other means.
• adhesives and putties that use a mixture of liquid A (base) and liquid B (hardener), but these are epoxy resins, a type of thermosetting resin, 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.
• the content of the base material in the composite material of this embodiment is preferably 20 to 90 parts by mass per 100 parts by mass of the reinforcing material.
• the content of the base material is more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, per 100 parts by mass of the reinforcing material.
• the content of the base material is 85 parts by mass or less, and even more preferably 80 parts by mass or less, per 100 parts by mass of the reinforcing material.
• 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 composite material of the present embodiment can be 0.01% by mass or less and 80% by mass or less, based on 100% by mass of the composite material.
• the method for treating a composite material of the present embodiment includes a step of recovering the reinforcing material from a composite material composed of a resin and a reinforcing material by decomposing the resin using sulfuric acid and heat.
• the step of decomposing the resin to recover the reinforcing material may, for example, be A) obtaining a treatment solution containing an oxidizing active species by electrolyzing sulfuric acid; B) A step of immersing the composite material, which is a scrap material discarded after use or from a manufacturing process, in the treatment solution to decompose and remove the base material; C) washing and drying the reinforcing material from which the base material has been removed, thereby regenerating the reinforcing material.
• the method for treating a composite material of this embodiment further includes a step of recovering the gas generated by decomposing the resin, and the proportion of carbon dioxide in the recovered gas is 90% by weight or more.
• the ratio of carbon dioxide in the recovered gas is preferably 92% by weight or more, and more preferably 95% by weight or more.
• the composite material processing method of this embodiment preferably further includes a step of utilizing the recovered gas as an industrial raw material. Utilizing the carbon dioxide in the gas generated during the thermal decomposition of the resin as an industrial raw material is particularly preferable from the viewpoint of effectively utilizing the recovered gas with a high carbon dioxide concentration.
• the gas recovery step is not particularly limited as long as the gas generated by decomposing the resin is recovered and the recovered gas contains 90% by mass or more of carbon dioxide, but it is preferable to include a step of separating oxygen and nitrogen from the recovered gas. This allows the carbon dioxide in the gas generated during pyrolysis to be recovered more efficiently.
• the main methods for separating carbon dioxide from oxygen and nitrogen include (1) chemical absorption, in which carbon dioxide is dissolved in an absorbing solution; (2) physical adsorption, in which carbon dioxide is adsorbed onto a solid adsorbent; (3) physical absorption, in which high-pressure carbon dioxide is physically adsorbed into an absorbing solution; (4) membrane separation, in which carbon dioxide is separated using a membrane that only allows carbon dioxide to pass through; and (5) cryogenic separation, in which carbon dioxide is liquefied at extremely low temperatures and then separated using differences in boiling points.
• (4) membrane separation in which carbon dioxide is separated using a membrane that only allows carbon dioxide to pass through, is preferred because it can handle high carbon dioxide concentrations and consumes little energy in the separation.
• separation membranes include polymer membranes such as polyimide, cellulose acetate, polysulfone, polycarbonate, thermally rearranged (TR) polymer membranes and PIM (polymer of intrinsic microporosity) membranes, facilitated transport membranes using alkali metal salts or amine compounds as carriers, ionic liquid-containing membranes using ionic liquid as carriers, zeolite membranes with a porous structure in which molecular sieving ability due to angstrom-sized pores has been introduced into the membrane, amorphous silica membranes and metal-doped silica membranes, carbon membranes with a porous structure derived from organic matter, and metal-organic frameworks (MOFs). These membranes may be used alone or in combination.
• polymer membranes such as polyimide, cellulose acetate, polysulfone, polycarbonate, thermally rearranged (TR) polymer membranes and PIM (polymer of intrinsic microporosity) membranes
• methods for decomposing the resin include sulfuric acid and heating.
• sulfuric acid it is preferable to use sulfuric acid, and it is more preferable to use an electrolytic sulfuric acid method, as this allows the resin to be decomposed more efficiently.
• the electrolytic sulfuric acid method is a method for treating a composite material, characterized in that a 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 and carbon dioxide, and the decomposition products are dissolved in the treatment solution, and then the reinforcing material is removed from the treatment solution.
• 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.
• the sulfuric acid solution is a solution consisting of sulfuric acid (H 2 SO 4 ) and water (H 2 O).
• the concentration of sulfuric acid contained in the sulfuric acid solution is preferably 30 to 95% by weight, more preferably 50 to 80% by weight. If the concentration of sulfuric acid is less than 30% by weight, the amount of oxidizing active species required to decompose the base material of the composite material cannot be obtained, and it takes a long time to decompose the base material.
• concentrated sulfuric acid, hydrochloric acid, or nitric acid may be added to the treatment solution containing the electrolyzed oxidizing active species.
• peroxides such as hydrogen peroxide and peroxosulfuric acid may be added to the treatment solution. In this case, the effect of accelerating the decomposition rate of the base material of the reinforced composite material can be obtained.
• the electrolysis device for sulfuric acid solution it is preferable to use a diaphragm-type electrolysis cell using diamond electrodes.
• the electrolysis conditions may be a current density of 0.01 to 10 A/cm 2 and a voltage of 0.1 to 100 V, but these may be appropriately changed depending on the type of electrode, the sulfuric acid concentration of the sulfuric acid solution, the amount of the sulfuric acid solution, etc.
• the electrolysis must be carried out in a closed system, and is preferably carried out while circulating a predetermined amount of sulfuric acid solution in a closed sulfuric acid solution circulation system.
• the circulation method may be a method using a pump or the like to pass the solution parallel to the electrode surface at a flow rate of 50 mL/min or more, or a method using natural circulation by convection with the flow of gas generated by electrolysis.
• the electrolysis processing time can be changed 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 processing for 0.5 to 10 hours per 1 L of sulfuric acid solution is preferred in terms of efficiently generating oxidizing active species.
• sulfuric acid of different concentrations may be used at both electrodes.
• 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 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.
• Electricity can be procured from a variety of possible 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.
• electricity generated from so-called renewable energy sources such as solar cells.
• the hydrogen (generated from the cathode) and oxygen (generated from the anode) generated by electrolysis can be collected and converted into electricity or heat.
• the sulfuric acid solution containing the obtained oxidizing active species can be supplied to a treatment tank for decomposing the base material of the composite material by either a method in which the solution is continuously supplied to the treatment tank from an electrolytic device using a pump or the like (continuous method), or a method in which the sulfuric acid solution is circulated in a closed system, and a treatment solution is collected from the system after electrolysis and supplied to the treatment tank (batch method).
• the collected treatment solution may also be combined with a device that can heat, cool, or pressurize it.
• the treatment solution used to treat the composite material can be reused, so it can be recovered, its concentration adjusted, and reused as sulfuric acid solution for electrolysis to generate active oxidizing species again.
• the treatment solution containing the oxidizing active species is preferably heated to enhance the decomposition of the base material of the composite material.
• the heating temperature is related to 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 base material of the 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.
• the treatment solution may be heated under pressure or reduced pressure.
• the temperature of the decomposition solution is heated and maintained at 100°C to 200°C, and after the resin is decomposed, the reinforcing material can be recovered by filtering, washing, and drying.
• this embodiment may further include a step of supplying oxygen into the decomposition solution.
• the decomposition rate of the resin that constitutes the composite material can be accelerated by supplying oxygen to the decomposition solution, so that high-quality reinforcing material can be recovered more efficiently than with conventional technologies without placing a burden on the environment.
• the supply of oxygen promotes the oxidative decomposition reaction, so that the ratio of carbon dioxide in the generated gas can be increased. The presence of sufficient oxygen in the decomposition process allows the oxidative decomposition reaction to proceed completely, and tends to lower the carbon monoxide ratio and increase the carbon dioxide ratio.
• Both carbon dioxide and carbon monoxide are water-soluble acidic gases and are difficult to separate.
• a high carbon dioxide ratio is required, so by reducing the carbon monoxide ratio, the gas can be suitably used as an industrial raw material as carbon dioxide.
• the step of supplying oxygen to the decomposition solution is not particularly limited, but from the viewpoint of further increasing the decomposition efficiency, it is preferable to supply oxygen when the composite material is immersed and heated.
• the method of supplying oxygen is not particularly limited, but examples include the introduction of single gases such as pure oxygen and ozone, and mixed gases of these single gases with other gases.
• the mixed gas can also be a mixed gas with an inert gas.
• air it is preferable to use air as the mixed gas, and in the process of supplying oxygen to the decomposition solution, a mixed gas of the single gases or mixed gases mentioned above and air can also be used.
• the method of introducing the elemental gas or the mixed gas into the decomposition solution is not particularly limited, and examples include a method of bubbling the elemental gas or the mixed gas into the reaction system.
• the means for introducing the simple gas or the mixed gas can be various means such as inserting it into the reaction system, directly connecting it to the reaction vessel, etc.
• a pump for supplying gas or an air header for storing the gas supplied from the pump can be used for introducing the simple gas or the mixed gas, and it is more preferable to introduce the simple gas or the mixed gas by microbubbling.
• the elemental gas or the mixed gas introduced into the decomposition solution is a mixed gas containing 15% by volume or more of the elemental gas, and it is preferable to introduce the mixed gas at 0.01 NL/sec or more into the decomposition solution. This is because the decomposition speed of the resin can be further increased.
• the mixed gas it is preferable to introduce the mixed gas at 0.01 NL/sec or more into the system (the decomposition solution) from the start of the treatment. More preferably, it is preferable to introduce the mixed gas into the system from the start of the treatment within the range of 0.01 NL/sec to 1 NL/sec.
• examples of a method for supplying oxygen other than introducing the single gas or the mixed gas include adding, to the decomposition solution, peroxides such as hydrogen peroxide, benzoyl peroxide, and peracetic acid, peracid, perchloric acid, permanganic acid, nitric acid, and salts thereof. It is preferable that the peroxide, peracid, perchloric acid, permanganic acid, nitric acid, and salts thereof are added to the decomposition solution at 0.01 mL/sec or more. This is because the decomposition rate of the resin can be further increased.
• peroxides such as hydrogen peroxide, benzoyl peroxide, and peracetic acid, peracid, perchloric acid, permanganic acid, nitric acid, and salts thereof. It is preferable that the peroxide, peracid, perchloric acid, permanganic acid, nitric acid, and salts thereof are added to the decomposition solution at 0.01
• the compound is introduced into the system (the decomposition solution) at a rate of 0.01 mL/sec or more from the start of the treatment. More preferably, it is preferable that the compound is introduced into the system at a rate within the range of 0.01 mL/sec to 1 mL/sec from the start of the treatment.
• the process of separating water vapor include cooling and treatment with a water vapor removal membrane.
• a decomposition liquid which is an aqueous solution of sulfuric acid or the like
• water vapor is mixed into the generated gas.
• the strength of the recycled reinforcing material is 80% or more of the strength of the reinforcing material before recycling, and that the shape retention rate of the reinforcing material before and after recycling is 90% or more. Furthermore, in this embodiment, when regenerated using the regenerating method of the reinforcing material 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 80% or more.
• the strength of the reinforcing material, the shape retention rate before and after recycling, and the strength ratio of the reinforcing material can be measured by the following methods.
• Strength of Reinforcing Material For fibrous reinforcing materials, the strength in the longitudinal direction was measured using a universal tensile tester (EZ TEST-5N manufactured by Shimadzu Corporation) at 23°C and a tensile speed of 1.5 mm/min. The strength was measured by averaging the strengths of 80 randomly selected fibrous reinforcing materials. The strength of the particulate reinforcing material was measured using a micro-compression tester (MCT-510 manufactured by Shimadzu Corporation) at 23° C. under a load of 1000 mN.
• the strength was measured by averaging the strengths of 50 randomly selected particulate reinforcing materials.
• Shape retention rate The shape retention rate was calculated by measuring the diameter of the reinforcing material using a scanning probe microscope (Shimadzu Corporation SPM-9700) and calculating the ratio of the diameter before and after regeneration. The following values were used as the diameters to calculate the ratio according to the shape of the reinforcing material.
• fibrous reinforcement the diameter in the width direction was measured, and the average of the measured values of 10 randomly selected fibrous reinforcement was used.
• For particulate reinforcing materials the average major and minor diameters were measured, and the average major and minor diameters of any ten particulate reinforcing materials were used.
• the fiber length of the recycled reinforcing material is preferably 0.5 ⁇ m or more, more preferably 1 ⁇ m or more, and even more preferably 10 mm or more.
• the aforementioned recycled reinforcing material may be appropriately processed to produce an intermediate substrate.
• the intermediate substrate in this embodiment may be a continuous fiber or nonwoven fabric containing recycled reinforcement material.
• a recycled composite material may be produced by compounding the above-mentioned recycled reinforcing material and the above-mentioned intermediate base material in a base material such as a resin.
• the strength of the recycled composite material is preferably 65% or more, more preferably 70% or more, and even more preferably 75% or more of the strength of the composite material made using the reinforcing material before recycling. Furthermore, the strength of the recycled composite material is preferably 80% or less, more preferably 90% or less of the strength of the composite material made using the reinforcing material before recycling. The strength of the composite material is measured in the same manner as the strength of the reinforcing material described above.
• the composite material regeneration of this embodiment uses the composite material processing method of this embodiment described above, in which the resin is decomposed from a composite material composed of a resin and a reinforcing material by using sulfuric acid and heat to recover the reinforcing material, and then: D) A process of regenerating a composite material by combining the recovered (regenerated) reinforcing material with a base material; can be implemented.
• the gas in this embodiment is recovered from a composite material composed of a resin and a reinforcing material when the resin is decomposed with sulfuric acid and heat to recover the reinforcing material.
• the ratio of carbon dioxide in the recovered gas of this embodiment is preferably 90% by weight or more. This makes it possible to not only recover the reinforcing material after decomposing the resin in the composite material, but also to recover the gas, making it possible to efficiently obtain and reuse the carbon dioxide in the gas generated during pyrolysis.
• the recycling system of the present embodiment is a recycling system including a process for recovering a reinforcing material from a composite material composed of a resin and a reinforcing material by decomposing the resin using sulfuric acid and heat, The gas, liquid or solid generated during the decomposition of the resin is reused as an industrial raw material.
• each epoxy resin raw material and polyvinyl formal are stirred for 1 to 3 hours while being heated to 150 to 190° C., so as to dissolve the polyvinyl formal uniformly.
• the resin temperature is lowered to 90 to 110° C., a phosphorus compound is added, and the mixture is stirred for 20 to 40 minutes.
• the resin temperature is lowered to 55 to 65° C., dicyandiamide and 3-(3,4-dichlorophenyl)-1,1-dimethylurea are added, and the mixture is kneaded at that temperature for 30 to 40 minutes, and then removed from the kneader to obtain a resin composition.
• the prepared resin composition was applied onto a release paper using a reverse roll coater to prepare a resin film.
• the amount of resin per unit area of the resin film was 25 g/ m2 .
• the reinforcing material is uniformly aligned in a sheet shape so that the weight of the reinforcing material per unit area is 100 g/ m2 , the above-mentioned resin film is superimposed on both sides of the reinforcing material, and the reinforcing material is impregnated with the resin composition by heating and pressurizing to produce a unidirectional prepreg.
• the prepreg is cured at 150° C. for 30 minutes to prepare an evaluation sample.
• the temperature was set to 50 ° C, the degree of vacuum was gradually increased over 5 hours, and the mixture was kept at 0.13 KPa for 15 hours to obtain a uniform dense membrane with a thickness of 350 ⁇ m.
• the reaction between polydimethylsiloxane having silanol groups at both ends and PEO2 was confirmed using DSC from the change in Tg of PEO2. That is, PEO2 had a Tg of -65°C, but after the film was formed, the Tg of PEO2 at -65°C disappeared due to the reaction with polydimethylsiloxane, and the Tg of the obtained gas separation membrane was only at -42°C.
• Carbon dioxide ratio (%) mass of carbon dioxide / total mass of recovered gas ⁇ 100%
• Example 1 The reinforcing material was separated and recovered from the composite material using the electrolytic sulfuric acid method 1. Specifically, a diamond electrode with an electrode area of 7 cm2 was used, and a sulfuric acid aqueous solution with a concentration of 60% was electrolyzed in a diaphragm-type electrolysis cell while the electrode was water-cooled to produce a treatment solution containing oxidizing active species. The amount of sulfuric acid aqueous solution electrolyzed in one run was 100 mL. The current was 0.3-1.0 A/ cm2 , the voltage was 17-20 V, and the electrolysis time was 120 minutes. 0.5 g of the composite material was immersed in 50 mL of the treatment solution containing the prepared oxidizing active species.
• the decomposition conditions were air atmosphere, 140° C., and 6 hours.
• the gas generated by decomposition was collected while being cooled in a Liebig condenser. Thereafter, the recovered gas was obtained through the above-mentioned gas separation process.
• the carbon dioxide ratio of the obtained recovered gas was 95%.
• the reinforcing material was recovered by filtering the decomposition liquid and drying it in a vacuum. Carbon fibers could be collected in the form of fibers, and glass fibers could be collected in the form of fibers.
• Example 2 The reinforcing material was separated and recovered from the composite material using the electrolytic sulfuric acid method 2. Specifically, a diamond electrode with an electrode area of 7 cm2 was used, and a sulfuric acid aqueous solution with a concentration of 60% was electrolyzed in a diaphragm-type electrolysis cell while the electrode was water-cooled to prepare a treatment solution containing oxidizing active species. The amount of sulfuric acid aqueous solution electrolyzed in one run was 100 mL. The current was 0.3-1.0 A/cm2, the voltage was 17-20 V, and the electrolysis time was 120 minutes.
• Example 3 The reinforcing material was separated and recovered from the composite material using the electrolytic sulfuric acid method 3. Specifically, a diamond electrode with an electrode area of 7 cm2 was used, and a sulfuric acid aqueous solution with a concentration of 60% was electrolyzed in a diaphragm-type electrolysis cell while the electrode was water-cooled to prepare a treatment solution containing oxidizing active species. The amount of sulfuric acid aqueous solution electrolyzed in one run was 100 mL. The current was 0.3-1.0 A/cm2, the voltage was 17-20 V, and the electrolysis time was 120 minutes.
• Example 4 The reinforcing material was separated and recovered from the composite material using a sulfuric acid + hydrogen peroxide method. 10 mL of commercially available 30% hydrogen peroxide solution (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to 40 mL of commercially available 64% sulfuric acid (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and 0.5 g of the composite material was immersed in the solution.
• the decomposition conditions were an air atmosphere, 140° C., and 12 hours.
• the gas generated by decomposition was collected while being cooled in a Liebig condenser. Thereafter, the recovered gas was obtained through the above-mentioned gas separation process. The carbon dioxide ratio of the obtained recovered gas was 90%.
• the reinforcing material was recovered by filtering the decomposition liquid and drying it in a vacuum. Carbon fibers could be collected in the form of fibers, and glass fibers could be collected in the form of fibers.
• the solution after decomposition was brown and contained residual organic matter.
• the reinforcing material was recovered by filtering the decomposition liquid and drying it in a vacuum. Carbon fibers could be collected in the form of fibers, and glass fibers could be collected in the form of fibers.
• the reinforcing material was separated and recovered from the composite material using the electrolytic sulfuric acid method 2. Specifically, a diamond electrode with an electrode area of 7 cm2 was used, and a sulfuric acid aqueous solution with a concentration of 60% was electrolyzed in a diaphragm-type electrolysis cell while the electrode was water-cooled to produce a treatment solution containing oxidizing active species. The amount of sulfuric acid aqueous solution electrolyzed in one run was 100 mL. The current was 0.3-1.0 A/ cm2 , the voltage was 17-20 V, and the electrolysis time was 120 minutes.
• the reinforcing material was separated and recovered from the composite material using the electrolytic sulfuric acid method 2. Specifically, a diamond electrode with an electrode area of 7 cm2 was used, and a sulfuric acid aqueous solution with a concentration of 60% was electrolyzed in a diaphragm-type electrolysis cell while the electrode was water-cooled to produce a treatment solution containing oxidizing active species. The amount of sulfuric acid aqueous solution electrolyzed in one run was 100 mL. The current was 0.3-1.0 A/ cm2 , the voltage was 17-20 V, and the electrolysis time was 120 minutes.
• Examples 1 to 4 it was shown that the carbon dioxide ratio of the generated decomposition gas was high and the purity was such that it could be used as a raw material for industrial materials. Furthermore, according to Examples 1 to 4, it was possible to recover the reinforcing materials, carbon fiber and glass fiber, in a fibrous form, and it was shown that this method is effective as a method for separating and recovering reinforcing materials. In Comparative Examples 1 to 8, organic matter remained in the decomposition liquid, so decomposition gas was not generated, or the carbon dioxide ratio in the decomposition gas was low, so it could not be used as an industrial raw material, and it was shown that this was not an effective method for separating and recovering reinforcing materials.
• the present invention provides a method for processing composite materials that not only allows the recovery of reinforcing materials from reinforced composite materials, but also allows the carbon dioxide gas generated during decomposition to be used as an industrial raw material. This makes it possible to significantly reduce the burden on the environment.

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• 2023
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