Classifications

• • 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
  • 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
  • C08J11/18—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 organic material
  • C08J11/22—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 organic material by treatment with organic oxygen-containing compounds
• • 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 depolymerization method.
• Polyamide resins have excellent mechanical properties such as mechanical strength, rigidity and impact resistance, as well as excellent heat resistance and chemical resistance. , and other industrial products.
• plastic industry is also required to respond to a resource recycling society, and the establishment of recycling technology is also required for polyamide resins.
• polyamide resin compositions and molded articles for automotive applications contain, in addition to polyamide resins, inorganic fillers such as glass fibers, various additives such as heat stabilizers, pigments, dyes, etc.
• in material recycling it is difficult to maintain practically sufficient mechanical properties after recycling. Therefore, chemical recycling, in which polyamide resin is depolymerized to decompose it into monomers such as diamine and dicarboxylic acid, and these monomers are polymerized again for recycling, is considered promising, and research and development is underway. .
• Patent Document 1 proposes a technology for producing monomers by decomposing a polyamide resin by ammonolysis using a Lewis acid catalyst.
• Patent Document 2 proposes a method of separating a polyamide resin and glass fibers from a molded article of a glass fiber-containing polyamide resin composition using an aqueous solution of phosphoric acid, and further decomposing the polyamide resin into monomers.
• Patent Document 1 has a problem of low monomer yield.
• the method described in Patent Document 2 requires as much as 200 minutes to dissolve the polyamide resin and the glass fiber in a specific example using polyamide 66.
• Patent Document 2 there is no specific description of the depolymerization method, and furthermore, it takes as long as 200 minutes to dissolve the polyamide resin and the glass fiber. Assuming that the polyamide resin is further depolymerized later, the total time becomes even longer, resulting in a problem of lack of practicality.
• Patent Documents 1 and 2 have the problem that the yield of the monomer is low and the time including recovery and depolymerization of the monomer lacks practicality.
• the process is performed under conditions such as high temperature and high pressure in order to shorten the time, the energy required for the process increases, and it is not practical from the viewpoint of reducing greenhouse gas (GHG) emissions. have.
• GFG greenhouse gas
• a polyamide resin, a polyamide resin composition, and a method for depolymerizing a molded article, which have a high monomer yield and excellent energy efficiency for depolymerization are provided.
• the present inventors have made intensive studies to solve the above-described problems of the prior art, and found that a polyamide resin, a polyamide resin composition, and a molded article thereof are heated and depolymerized in a predetermined solvent. As a result, the inventors have found that the above problems can be effectively solved, and have completed the present invention. That is, the present invention is as follows.
• the present invention it is possible to provide a depolymerization method capable of monomerizing a polyamide resin, a polyamide resin composition, and a molded article thereof at a high yield with low energy.
• the inorganic salt is 1% by mass or more and 25% by mass or less with respect to 100% by mass of the solvent, and the water is 30% by mass or more and 99% by mass with respect to 100% by mass of the solvent.
• polyamide resin used in the depolymerization method of this embodiment means a polymer having an amide bond (--NHCO--) in the main chain.
• the polyamide resin composition used in the depolymerization method of the present embodiment includes the polyamide resin, and, if necessary, an inorganic filler such as glass fiber, a lubricant, and other additives such as a heat stabilizer, a flame retardant, a pigment, It is a resin composition containing components such as dyes.
• the molded article used in the depolymerization method of the present embodiment is a molded article of the polyamide resin or the polyamide resin composition, and can be produced by molding using various known methods such as injection molding.
• the molded article used in the depolymerization method of the present embodiment may be fibers of a polyamide resin or a polyamide resin composition.
• the polyamide resin, the polyamide resin composition, and the constituent materials of their molded articles used in the depolymerization method of the present embodiment are specifically shown below.
• polyamide resins include, but are not limited to, polyamide 4 (poly ⁇ -pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (poly tetramethylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 410 (polytetramethylene sebacamide), polyamide 412 (polytetramethylene dodecamide), Polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 1010 (polydecamethylene sebacamide), polyamide 1012 (polydecamethylene dodecamide), polyamide 6T (polyhexamethylene terephthalamide ), polyamide 9T (polynonanemethylene terephthalamide), polyamide 6I (polyhexamethylene terephthalamide),
• the polyamide resin is preferably one or more selected from the group consisting of polyamide 66, polyamide 66/6I, polyamide 610, polyamide 612, polyamide 6I, and polyamide 6, and polyamide 66, polyamide 66/6I, or polyamide 66. and polyamide 6I are more preferred.
• Polyamide 66 is a polyamide obtained by polycondensation of hexamethylenediamine and adipic acid, and is excellent in heat resistance, mechanical strength, and creep properties, so it is suitably used as a material for functional parts of automobiles, machines, and electrical products.
• the polyamide resin composition and molded article used in the depolymerization method of the present embodiment may contain an inorganic filler.
• polyamide resin compositions and molded articles tend to have excellent mechanical strength and rigidity.
• inorganic fillers include, but are not limited to, glass fiber, carbon fiber, calcium silicate fiber, potassium titanate, aluminum borate, glass flakes, glass beads, talc, kaolin, mica, hydrotalcite, carbonate Calcium, zinc carbonate, zinc oxide, calcium monohydrogen phosphate, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesium oxide, calcium silicate, sodium aluminosilicate, magnesium silicate , ketjen black, acetylene black, furnace black, carbon nanotubes, graphite, brass, copper, silver, aluminum, nickel, iron, calcium fluoride, mica, montmorillonite, swelling fluoromica, apatite and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.
• the polyamide resin composition and molded article used in the depolymerization method of the present embodiment may contain a lubricant in addition to the polyamide resin and the inorganic filler.
• a lubricant in addition to the polyamide resin and the inorganic filler.
• the polyamide resin composition and molded article used in the depolymerization method of the present embodiment may contain other additives in addition to the polyamide resin, inorganic filler, and lubricant component.
• Other additives include, for example, antioxidants, ultraviolet absorbers, heat stabilizers, photodegradation inhibitors, plasticizers, release agents, nucleating agents, flame retardants, colorants, and other thermoplastic resins. .
• the polyamide resin in the solvent containing 1% by mass or more and 25% by mass of an inorganic salt and a polyhydric alcohol with respect to 100% by mass of the solvent, the polyamide resin, the polyamide It has a step of heating and depolymerizing at least one selected from the group consisting of resin compositions and molded articles thereof.
• the inorganic salt is 1% by mass or more and 25% by mass or less with respect to 100% by mass of the solvent, and the water is 30% by mass or more with respect to 100% by mass of the solvent.
• a step of heating at least one selected from the group consisting of a polyamide resin, a polyamide resin composition, and molded articles thereof in the solvent containing 99% by mass or less to depolymerize.
• the solvent used in the first mode of the depolymerization method of the present embodiment contains 1% by mass or more and 25% by mass of an inorganic salt and a polyhydric alcohol with respect to 100% by mass of the solvent. Further, the solvent used in the second mode of the depolymerization method of the present embodiment is 1% by mass or more and 25% by mass or less of an inorganic salt with respect to 100% by mass of the solvent, and 30% by mass of water with respect to 100% by mass of the solvent. 99% by mass or less is included.
• the content of water in the solvent is 30% by mass or more and 99% by mass or less, preferably 35% by mass or more and 90% by mass or less, More preferably, it is 40% by mass or more and 80% by mass or less.
• Inorganic salt is a general term for salts composed only of inorganic components, and includes, for example, metal salts, which are compounds in which hydrogen atoms of acids are replaced with metal ions.
• metal salts include, but are not limited to, halides of calcium, zinc, and lithium from the viewpoint of being suitable for depolymerization.
• calcium chloride, zinc chloride, zinc bromide, Chromium bromide, iron bromide, lithium chloride, lithium bromide, cobalt chloride and the like From the viewpoint of availability and safety, calcium chloride, zinc chloride and lithium chloride are preferred.
• the amount of the metal salt used in the depolymerization step is 1% by mass or more and 25% by mass or less, preferably 5% by mass or more and 20% by mass or less, and 10% by mass or more and 15% by mass or less with respect to 100% by mass of the solvent. The following are more preferred.
• the use of a solvent containing an inorganic salt has the effect of weakening the hydrogen bonds between the polymer chains of the polyamide to facilitate depolymerization.
• the amount of the inorganic salt is 1% by mass or more in the solvent from the viewpoint of the amount necessary to weaken the hydrogen bond, and from the viewpoint of suppressing the generation of by-products during depolymerization separation and purification. , 25% by mass or less in the solvent.
• Polyhydric alcohols include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, diglycerin, triglycerin, threitol, Erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, mannitol and the like.
• Ethylene glycol is particularly preferred from the viewpoint of solubility.
• the solvent used in the depolymerization method of the present embodiment may contain polyhydric alcohol, inorganic salt, and water as constituent components, and may further contain other components as necessary.
• a mixed solvent in which other solvents are used together may be used.
• water or methanol may be mixed as a poor solvent.
• the mixing ratio is preferably 1 to 9 of the poor solvent per 1 of the polyhydric alcohol.
• a mixed solvent containing 1 to 9 parts by mass of methanol or water to 1 part of ethylene glycol can be used.
• it is a mixed solvent containing a poor solvent to 1 polyhydric alcohol at a mass ratio of 1 to 3, and more preferably a poor solvent to 1 polyhydric alcohol at a mass ratio of 1 to 2.
• It is a mixed solvent containing
• the polyamide resin does not need to be completely dissolved at the start of heating, and dissolution and decomposition due to depolymerization may proceed in parallel. That is, the dissolved polyamide resin may be sequentially depolymerized and decomposed into monomers.
• an acid such as formic acid, phosphoric acid, sulfuric acid, or hydrochloric acid may be further added to the solvent.
• the depolymerization method of the present embodiment at least one selected from the group consisting of polyamide resins, polyamide resin compositions, and molded articles thereof is heated in the solvent described above.
• the temperature in the system during heating is preferably 210°C or less, more preferably 70 to 200°C, and even more preferably 100 to 190°C.
• any known method such as steam or an electric heater can be applied.
• the residual rate of the polyamide resin is set to 10% by mass or less, and dicarboxylic acids, diamines, lactams, and derivatives thereof, which are decomposition products of the polyamide resin, are added to the above-mentioned
• the amount is 70% by mass or more with respect to 100% by mass of the polyamide resin before the depolymerization step.
• the residual rate of the polyamide resin is more preferably 7% by mass or less, and even more preferably 5% by mass or less.
• the amount of the decomposition product is preferably 75% by mass or more, more preferably 80% by mass, based on 100% by mass of the polyamide resin before the depolymerization step.
• the residual ratio of the polyamide resin can be controlled within the above numerical range by adjusting the reaction time and temperature.
• the amount of the decomposition products can be controlled within the above numerical range by adjusting the reaction time and temperature.
• the residual ratio of the polyamide resin in the reaction solution after the depolymerization step, and the quantification of dicarboxylic acids, diamines, lactams, and derivatives thereof, which are decomposition products, can be determined by GPC, NMR, liquid chromatography, gas chromatography, and FT. It can be carried out by a known method such as -IR. For example, the method described in Non-Patent Document 1 below can be used.
• a known method can be used to purify the decomposition products.
• adipic acid can be purified by a method of precipitation and recrystallization
• hexamethylenediamine can be purified by a method such as distillation.
• Polyamide resin Polyamide resin composition, molded article used in depolymerization step
• polyamide resin A: Polyamide 66 (manufactured by Asahi Kasei Corporation, model number: Leona 1300)
• Polyamide resin composition B Polyamide 66 resin composition (manufactured by Asahi Kasei Corporation, model number: Leona 14G33, glass fiber ratio 33%)
• (Molded article of polyamide resin composition) C A molded article of a polyamide 66 resin composition was produced as follows. The Leona 14G33 (manufactured by Asahi Kasei) was dried in a nitrogen stream to reduce the water content in the polyamide resin composition to 500 ppm or less to obtain pellets of the polyamide resin composition. Next, using pellets of the polyamide resin composition with adjusted moisture content, using an injection molding machine (SE-50D manufactured by Sumitomo Heavy Industries, Ltd.), in accordance with ISO 3167, a multi-purpose test piece (A type, dumbbell shape A tensile test piece) was molded.
• SE-50D manufactured by Sumitomo Heavy Industries, Ltd.
• the dimensions of the multi-purpose test piece were as follows: total length ⁇ 170 mm, distance between tabs 109.3 ⁇ 3.2 mm, length of parallel portion 80 ⁇ 2 mm, radius of shoulder 24 ⁇ 1 mm, width of end 20 ⁇ 0.2 mm. 2 mm, the width of the central parallel portion was 10 ⁇ 0.2 mm, and the thickness was 4 ⁇ 0.2 mm.
• the conditions for injection molding were as follows: injection speed: 100 mm/sec (controlled by injection speed), injection time: 1 second, cooling time: 14 seconds, mold temperature: 80°C, cylinder temperature: 290°C.
• the resulting multipurpose test piece was used as a molded article of the polyamide resin composition.
• HMD hexamethylenediamine
• ADA adipic acid
• the reaction solution after depolymerization was measured using liquid chromatography (Agilent 1100, manufactured by Agilent Technologies), and a calibration curve prepared using a reference HMD (or derivative such as HMD hydrochloride) and ADA was used to determine the The amounts of HMD, ADA and derivatives thereof were determined with respect to the polyamide resin before polymerization.
• Tables 1 and 2 show the depolymerization conditions of the polyamide resins, the polyamide resin compositions, and the molded articles of Examples 1 to 10 and Comparative Examples 1 to 4, and the quantitative results of decomposition products resulting from the depolymerization.
• any solution selected from the group consisting of polyamide resins, polyamide resin compositions, and molded articles thereof in a solvent containing 1 to 25% by mass of a metal salt and containing a polyhydric alcohol By performing polymerization, a decomposition product containing a residual rate of polyamide resin of 10% by mass or less in a short time and a total of 70% by mass or more of dicarboxylic acid and diamine and their derivatives is obtained, and monomerized at a high yield. was able to achieve
• the depolymerization method of the present invention has industrial applicability as an efficient recycling method for polyamide resins, polyamide resin compositions, and molded articles used in automobile parts and various industrial parts.

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• Organic Chemistry (AREA)
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Citations (5)

• 2022
  • 2022-12-16 WO PCT/JP2022/046452 patent/WO2023120427A1/ja not_active Ceased
  • 2022-12-16 JP JP2023569402A patent/JP7772830B2/ja active Active

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