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
  • C08J11/14—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 steam or water
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
  • C07D201/02—Preparation of lactams
  • C07D201/12—Preparation of lactams by depolymerising polyamides
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
  • C07D201/16—Separation or purification
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D223/00—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom
  • C07D223/02—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings
  • C07D223/06—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D223/08—Oxygen atoms
  • C07D223/10—Oxygen atoms attached in position 2
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
  • C08G69/08—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino-carboxylic acids
  • C08G69/14—Lactams
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
  • C08G69/08—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino-carboxylic acids
  • C08G69/14—Lactams
  • C08G69/16—Preparatory processes
• • 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
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
• • 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 is a method for decomposing polyamide 6 that achieves both resource recycling and reduction of greenhouse gas emissions. More specifically, polyamide 6 is depolymerized using only a small amount of water, which has a high specific heat capacity and heat of vaporization. , relates to a recycling method for recovering high-purity ⁇ -caprolactam in high yield.
• Patent Literature 1 discloses a method of producing hydrocarbons by a process including pyrolysis and steam cracking of waste plastics. Although these methods have the advantage of being able to convert mixed waste plastics into pyrolysis oil, they require cracking at a high temperature of 800°C or higher in order to convert the pyrolysis oil into secondary raw materials such as plastic monomers.
• the ⁇ -caprolactam recovery method disclosed in Patent Document 2 is a high-yield reaction with a depolymerization yield of polyamide 6 of 80% or more, the depolymerization reaction takes a long time. Furthermore, since a large amount of superheated steam, about 10 times that of polyamide 6 fiber, is required, this technology remains a problem in achieving both the recycling of fossil resources and the reduction of greenhouse gas emissions. In addition, since this method uses phosphoric acid as a catalyst, the reaction is susceptible to impurities, such as catalyst deactivation due to additives contained in plastics and adhering impurities in waste plastics.
• the ⁇ -caprolactam recovery methods disclosed in Patent Documents 3 and 4 use only water for the depolymerization reaction, and do not use a catalyst such as phosphoric acid. There is an advantage that reaction deactivation due to does not occur.
• a large amount of water which has a specific heat capacity of 4.2 kJ/kg K and a heat of vaporization of 2,250 kJ/kg, is about 10 times that of polyamide 6. , a large amount of energy is required for the depolymerization reaction and recovery of ⁇ -caprolactam from a low-concentration ⁇ -caprolactam aqueous solution.
• thermodynamic equilibrium point of ⁇ -caprolactam produced by depolymerization and the linear oligomer produced by hydrolytic ring-opening of ⁇ -caprolactam shifted to the side of the linear oligomer simply by reducing the amount of water used. It is considered to be
• the present invention has the following configurations. 1.
• a resin composition (A) containing at least polyamide 6 with water (B) heated to 290° C. or higher and 350° C. or lower the mass ratio of water to polyamide 6 is X: 1.
• a method for producing ⁇ -caprolactam comprising obtaining ⁇ -caprolactam by any of the methods from 1 to 5 and polymerizing polyamide 6.
• the present invention can produce ⁇ -caprolactam with a high yield even when a small amount of water having a high specific heat capacity is used.
• a manufacturing method can be provided.
• Resin composition (A) is a method for producing ⁇ -caprolactam by bringing a resin composition (A) containing at least polyamide 6 into contact with water (B) heated to 290° C. or more and 350° C. or less.
• Polyamide 6 used in the present invention is a polyamide resin mainly composed of 6-aminocaproic acid and/or ⁇ -caprolactam. Other monomers may be copolymerized to the extent that the object of the present invention is not impaired.
• main raw material means that a total of 50 mol% or more of 6-aminocaproic acid-derived units or ⁇ -caprolactam-derived units is contained in a total of 100 mol% of the monomer units constituting the polyamide resin. means It is more preferable to contain 6-aminocaproic acid-derived units or ⁇ -caprolactam-derived units in an amount of 70 mol% or more, more preferably 90 mol% or more.
• Other monomers to be copolymerized include, for example, amino acids such as 11-aminoundecanoic acid, 12-aminododecanoic acid and para-aminomethylbenzoic acid, lactams such as ⁇ -laurolactam, tetramethylenediamine, pentamethylenediamine, Hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-/2,4,4-trimethylhexamethylenediamine, 5-methylnona Aliphatic diamines such as methylenediamine, aromatic diamines such as metaxylylenediamine and paraxylylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3 -aminomethyl-3,5,5-trimethylcyclohexane,
• polyamides 6 may be added with polymerization degree modifiers, terminal group modifiers, and the like.
• polymerization degree modifiers and terminal group modifiers include acetic acid and benzoic acid.
• the degree of polymerization of the polyamide 6 of the present invention is not particularly limited, but the relative viscosity measured at 25 ° C. in a 98% concentrated sulfuric acid solution with a resin concentration of 0.01 g / mL is in the range of 1.5 to 5.0 Preferably.
• the relative viscosity is in such a preferable range, the reaction efficiency with a small amount of water tends to be high, so it can be exemplified preferably.
• Polyamide 6 of the present invention may contain a cyclic oligomer represented by the following formula (a).
• the amount of the cyclic oligomer represented by the following formula (a) contained in polyamide 6 is not particularly limited, but is preferably 2.0% by mass or less, more preferably 1.8% by mass or less, and 1.5% by mass. It is more preferably exemplified that it is not more than mass %.
• m is an integer of 2-4.
• the cyclic oligomer represented by the following formula (a) melts and volatilizes, causing line clogging and the like.
• the resin composition (A) of the present invention can further contain an alkali metal halide within a range that does not impair the object of the present invention.
• alkali metal halides include alkali metal halides such as lithium iodide, sodium iodide, potassium iodide, lithium bromide, sodium bromide, potassium bromide, lithium chloride, sodium chloride and potassium chloride. , and two or more of these can be used in combination.
• potassium iodide is preferable from the viewpoint of easy availability, excellent dispersibility in polyamide 6, higher reactivity with radicals, and improved retention stability at high temperatures.
• alkali metal halides can be used in combination with Group 11 metal halides such as copper (I) iodide, copper (I) bromide, and copper (I) chloride to further improve the retention stability at high temperatures. It is more preferably used for
• alkali metal halides are preferably blended in an amount of 0.01 to 1 part by mass per 100 parts by mass of polyamide 6.
• the content of the alkali metal halide is more preferably 0.02 to 0.5 parts by mass, more preferably 0.03 to 0.4 parts by mass.
• the resin composition (A) of the present invention may contain a fibrous filler.
• a fibrous filler herein may be any filler having a fibrous shape. Specifically, glass fibers, polyacrylonitrile (PAN)-based and pitch-based carbon fibers, stainless steel fibers, metal fibers such as aluminum fibers and brass fibers, polyester fibers, organic fibers such as aromatic polyamide fibers, gypsum fibers, ceramics Fibers, asbestos fibers, zirconia fibers, alumina fibers, silica fibers, titanium oxide fibers, silicon carbide fibers, rock wool, potassium titanate whiskers, silicon nitride whiskers, wollastonite, fibrous and whisker fillers such as alumina silicate, nickel , copper, cobalt, silver, aluminum, iron, and alloys thereof. You may contain 2 or more types of these.
• the content of the fibrous filler is preferably 1 to 200 parts by mass with respect to 100 parts by mass of the resin composition (A).
• the resin composition (A) of the present invention may further contain fillers other than fibrous fillers, thermoplastic resins other than polyamide 6, and various additives within a range that does not impair the object of the present invention.
• Fillers other than fibrous fillers may be either organic fillers or inorganic fillers, and examples include non-fibrous fillers, and two or more of these fillers may be blended.
• non-fibrous fillers examples include talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, alumina silicate, non-swelling silicates such as calcium silicate, Li-type fluorine Swellable layered silicates such as teniolite, Na-type fluoroteniolite, Na-type tetrasilicon fluoromica, swelling mica of Li-type tetrasilicon fluoromica, silicon oxide, magnesium oxide, alumina, silica, diatomaceous earth, zirconium oxide, titanium oxide, Metal oxides such as iron oxide, zinc oxide, calcium oxide, tin oxide and antimony oxide, metal carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dolomite and hydrotalcite, calcium sulfate and barium sulfate metal hydroxides such as metal sulfates, magnesium hydroxide, calcium hydroxide, aluminum
• Organic onium ions include, for example, ammonium ions, phosphonium ions, and sulfonium ions.
• additives include N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide), tetrakis[methylene-3-(3',5'-di- Phenolic compounds such as t-butyl-4'-hydroxyphenyl)propionate]methane, phosphorus compounds, mercaptobenzimidazole compounds, dithiocarbamic acid compounds, sulfur compounds such as organic thioacid compounds, N,N'- Thermal stabilizers such as amine compounds such as di-2-naphthyl-p-phenylenediamine and 4,4'-bis( ⁇ , ⁇ -dimethylbenzyl)diphenylamine, isocyanate compounds, organic silane compounds, organic titanate compounds , organic borane compounds, coupling agents such as epoxy compounds, polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, plasticizers such as organic phosphorus compounds, crystal nuclei such as
• thermoplastic resins other than polyamide 6 contained in the resin composition (A) include polyamide resins other than polyamide 6, polyester resins, polyolefin resins, modified polyphenylene ether resins, polysulfone resins, polyketone resins, and polyetherimide resins. , polyarylate resin, polyether sulfone resin, polyether ketone resin, polythioether ketone resin, polyether ether ketone resin, polyimide resin, polyamideimide resin, tetrafluoropolyethylene resin, polyphenylene sulfide resin, and the like. You may mix
• the amount of the thermoplastic resin other than polyamide 6 is preferably 30 parts by mass or less per 100 parts by mass of polyamide 6 in the thermoplastic resin (A) of the present invention.
• the resin composition (A) containing polyamide 6 of the present invention may be waste of resin moldings containing at least polyamide 6.
• the waste of resin moldings containing polyamide 6 includes polyamide 6 products, industrial waste generated in the process of manufacturing polyamide 6 products, and waste after use of polyamide 6 products.
• Polyamide 6 products include textile structures for clothing such as used clothes, uniforms, sportswear and innerwear; industrial textile structures such as curtains, carpets, ropes, nets, belts and sheets; Examples include electronic molded parts, aircraft parts, industrial machine parts, film products, extrusion molded products, in-situ polymerized molded products, RIM molded products, and the like. Furthermore, product scraps, pellet scraps, lump-like scraps, and cutting scraps generated during the cutting process are also subject to waste.
• a resin composition (A) containing at least polyamide 6 is brought into contact with water (B) heated to 290°C or higher and 350°C or lower.
• water (B) heated to 290°C or higher and 350°C or lower When the mass ratio of water and polyamide 6 is X:1 and the reaction temperature is Y° C., the product of X and Y is 2,000 or less.
• the water (B) used here is not particularly limited, but any water such as tap water, ion-exchanged water, distilled water, and well water may be used. From the viewpoint of , ion-exchanged water and distilled water are preferably used.
• water heated to 290°C or higher and 350°C or lower is used as the water (B).
• water When water is raised to a pressure of 22.1 MPa and a temperature of 374.2° C., it becomes neither liquid nor gas. This point is called the critical point of water, and hot water at a temperature and pressure lower than the critical point is called subcritical water.
• the water (B) used in the present invention has a temperature of 290° C. or higher and 350° C. or lower and corresponds to subcritical water. Although this subcritical water is water, it has the characteristics of (i) a low dielectric constant and (ii) a high ionic product. It depends and can be controlled.
• the low dielectric constant makes it an excellent solvent for organic compounds, even though it is water, and the high ion product increases the concentration of hydrogen ions and hydroxide ions, resulting in an excellent hydrolytic action.
• the temperature of the water (B) of the present invention is preferably 300°C or higher and 340°C or lower, more preferably 320°C or higher and 340°C or lower. By being in such a preferable range, there is a tendency that corrosion of equipment during the reaction can be suppressed.
• a pressure of water (B) it can preferably be exemplified that it is higher than the saturated vapor pressure.
• Water (B) may be in a liquid state, a gaseous state such as water vapor, or both.
• the upper limit of the pressure of water (B) is not particularly limited, but can be exemplified as 20 MPa or less. Such a pressure range tends to increase the ionic product of water, which is preferable.
• a method of pressurizing and sealing the inside of the pressure vessel to bring the water (B) into such a pressure range is exemplified.
• gas in addition to water (B). Examples of such gas include air, argon, nitrogen, etc., but side reactions such as oxidation reactions are suppressed. From the viewpoint of this, it is preferable to use nitrogen or argon.
• the degree of gas pressurization is not particularly limited because it is set to a target pressure, but 0.3 MPa or more can be mentioned.
• the method for producing ⁇ -caprolactam of the present invention is characterized in that the product of X and Y is 2,000 or less, where the mass ratio of water and polyamide 6 is X:1, and the reaction temperature is Y°C. and
• the product of X and Y is preferably 1,600 or less, more preferably 1,300 or less, and particularly preferably 1,200 or less.
• the lower limit of the product of X and Y is not particularly limited, but a condition of preferably 300 or more, more preferably 320 or more, and particularly preferably 340 or more can be exemplified.
• the present invention relates to energy-saving production of ⁇ -caprolactam from a polyamide 6 resin composition for the purpose of achieving both the recycling of fossil resources and the reduction of greenhouse gas emissions.
• Water has a specific heat capacity of 4.3 kJ/kg K and a heat of vaporization of 2,250 kJ/kg, which are extremely high compared to other organic solvents.
• the residence time at the reaction temperature Y° C. is Z minutes
• the contact is preferably made under the condition that the product of X, Y and Z is 60,000 or less. More preferably 40,000 or less, still more preferably 30,000 or less, and particularly preferably 20,000 or less.
• the condition is preferably 5,000 or more, more preferably 8,000 or more, and particularly preferably 9,000 or more. can. Setting the product of X, Y, and Z within such a preferable condition range tends to increase the efficiency of producing ⁇ -caprolactam while saving energy, which is preferable.
• a side reaction of linear oligomer formation due to the reaction of ⁇ -caprolactam and water proceeds as a side reaction, and simply reducing the amount of water used. produces a large amount of linear oligomers, which greatly reduces the production efficiency of ⁇ -caprolactam.
• the present inventors have clarified the thermodynamic equilibrium points of the ⁇ -caprolactam production reaction by the reaction of polyamide 6 and water and the side reaction of linear oligomer production.
• the present inventors have found that by setting the product of and Z within the above range, the by-production of linear oligomers can be suppressed and the production efficiency of ⁇ -caprolactam can be greatly improved, leading to the present invention.
• ⁇ -caprolactam of the present invention various known reaction methods such as batch method and continuous method can be employed.
• it is a continuous type it is an extruder equipped with a heating function, a tubular reactor, a tubular reactor equipped with a mixing mechanism such as a baffle, a line mixer, a vertical or horizontal reactor, and a vertical reactor equipped with a stirrer.
• Type/horizontal reactors, towers, and the like The atmosphere in the production is desirably a non-oxidizing atmosphere, preferably an inert atmosphere such as nitrogen, helium, or argon, and a nitrogen atmosphere is preferable from the viewpoints of economy and ease of handling.
• the method for recovering ⁇ -caprolactam of the present invention is not particularly limited, and any method can be employed.
• the ⁇ -caprolactam aqueous solution is obtained by distilling it together with water after the completion of the depolymerization reaction.
• an ⁇ -caprolactam aqueous solution can be obtained as the reaction progresses.
• the resulting ⁇ -caprolactam aqueous solution is separated from water by distillation, whereby ⁇ -caprolactam with high purity can be recovered.
• the recovered aqueous solution of ⁇ -caprolactam contains water-insoluble components, they can be separated in advance by a known method such as solid-liquid separation and subjected to distillation separation.
• Methods for obtaining ⁇ -caprolactam of even higher purity include a method of precision distillation of recovered ⁇ -caprolactam, a method of vacuum distillation with the addition of a trace amount of sodium hydroxide, a method of activated carbon treatment, an ion exchange treatment method, and a recycling method. It can be combined with a purification method such as a method of crystallization. These methods can efficiently remove impurities that are difficult to separate by distillation.
• ⁇ -caprolactam with high purity can be obtained, so that it can be used as a raw material for polymerization of polyamide 6.
• Polyamide 6 can be produced by a generally known method of thermally melt-polymerizing ⁇ -caprolactam in the presence of a small amount of water. Further, the polyamide 6 obtained in this way is melt-kneaded with fibrous fillers and various additives as necessary to produce a polyamide 6 resin composition, and injection molding, extrusion molding, etc.
• Various molded articles such as sheets and films can be obtained by the method.
• the polyamide 6 of the present invention and its molded articles can be used for various purposes such as electric/electronic parts, building materials, various containers, daily necessities, household goods and sanitary goods, taking advantage of their excellent properties.
• it is preferably used for aircraft parts and electric/electronic parts that require toughness and rigidity.
• aircraft-related parts such as landing gear pods, winglets, spoilers, edges, rudders, elevators, failings, and ribs
• electrical and electronic parts such as generators, motors, transformers, and current transformers.
• the solution viscosity ⁇ r was measured at 25° C. using a 0.01 g/mL solution of 98% concentrated sulfuric acid.
• the melting point is measured by using a differential scanning calorimeter, in a nitrogen gas atmosphere, the temperature of the polyamide is lowered from the molten state to 30 ° C. at a temperature decrease rate of 20 ° C./min, and then the temperature is increased by 20 ° C./min.
• the temperature of the endothermic peak that appears when the temperature is raised to °C was taken as the temperature. However, when two or more endothermic peaks were detected, the temperature of the endothermic peak with the highest peak intensity was taken as the melting point.
• the amount of the cyclic dimer to tetramer oligomer is obtained by pulverizing polyamide 6, passing through a JIS standard sieve of 24 mesh, collecting polyamide 6 powder that is impermeable to 124 mesh, and adding 20 g of the polyamide 6 powder to 200 mL of methanol. Extraction was performed using a time Soxhlet extractor, and the cyclic oligomer contained in the extract was quantitatively analyzed using high performance liquid chromatography. The measurement conditions are as follows.
• Example 1 A SUS316L autoclave equipped with a stirrer was charged with 20.0 g of polyamide 6 (PA6-A) and 60.0 g of deionized water. The mass ratio (X:1) of water to polyamide 6 is 3:1. The reaction vessel was purged with nitrogen, sealed under a nitrogen pressure of 0.5 MPa, and then reacted at 340° C. for 15 minutes while stirring at 200 rpm. The ultimate pressure during the reaction was 13.2 MPa. After completion of the reaction, the reaction mixture was recovered by cooling to room temperature. Since the reaction temperature Y ° C. is 340 ° C., the product of X and Y is 1,020, and the residence time at the reaction temperature of 340 ° C.
• the energy required for production was 1,908 kcal/kg-Lcm.
• the reaction mixture recovered by the above reaction is subjected to distillation separation of water at a reduced pressure of 30 mmHg and a heating temperature of 55° C.
• ⁇ -caprolactam aqueous solution which is further distilled at a reduced pressure of 5 mmHg and a heating temperature of 150 to 170° C. to distill.
• ⁇ -caprolactam was obtained.
• the concentration and distillation yield was 95.8%.
• the HPLC impurity content of the distilled ⁇ -caprolactam was 0.48%, and the quality was such that it could be used as a raw material for polymerization of polyamide 6.
• Examples 2 to 8, Comparative Examples 1 to 4 Using PA6-A as a raw material, depolymerization was carried out in the same manner as in Example 1 while changing the amount of water relative to polyamide 6, the reaction temperature and the reaction time to produce ⁇ -caprolactam. Table 1 shows the reaction conditions, the ⁇ -caprolactam yield, and the amount of heating heat and energy required to produce 1 kg of ⁇ -caprolactam.
• Example 9 Using PA6-B to F as raw materials, depolymerization was carried out under the same conditions as in Example 2 while changing the amount of water relative to polyamide 6 to produce ⁇ -caprolactam. Table 2 shows the reaction conditions, the ⁇ -caprolactam yield, and the amount of heating and energy required to produce 1 kg of ⁇ -caprolactam.
• Example 15 High Pressure Reaction
• a SUS316L autoclave equipped with a stirrer was charged with 45.0 g of polyamide 6 (PA6-A) and 135.0 g of deionized water.
• the reaction vessel was purged with nitrogen, sealed under a nitrogen pressure of 5.0 MPa, and then reacted at 320° C. for 15 minutes while stirring at 200 rpm.
• the ultimate pressure during the reaction was 19.8 MPa.
• the reaction mixture was recovered by cooling to room temperature. Since the reaction temperature Y° C. is 320° C., the product of X and Y is 960. Since the residence time at the reaction temperature of 320° C.
• Example 16 Using PA6-A as a raw material, depolymerization was carried out in the same manner as in Example 15 by changing the amount of water (120 g) relative to polyamide 6 (60 g) to produce ⁇ -caprolactam. Table 3 shows the reaction conditions, the ⁇ -caprolactam yield, and the amount of heating heat and energy required to produce 1 kg of ⁇ -caprolactam.

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• 2022
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