Process for hydrolytic depolymerization of polyamides

Abstract

Disclosed is a process for hydrolytic depolymerization of a polyamide contained in a chemical feedstock F, wherein the process comprises: providing the chemical feedstock F; providing a liquid aqueous stream SW; preparing a mixture comprising the raw material F and the liquid aqueous stream SW and subjecting said mixture to polyamide 6 depolymerization conditions in a chemical reaction unit UR, thereby obtaining an aqueous stream SE exiting the UR, the stream SE comprising epsilon-caprolactam, wherein the mixture to be subjected to polyamide 6 depolymerization conditions comprises polyamide 6 and further comprises polyethylene terephthalate and polyamide 6.6 in a mass ratio rS = (mPA6.6 + mPET) / mPA6, wherein 0.01 < = rS < = 2.5.

Description

[0001] This invention relates to a method for hydrolyzing polyamide 6, wherein the polyamide 6 is contained in a chemical raw material comprising, in addition to, a specific amount of polyethylene terephthalate and polyamide 6.6. Furthermore, this invention relates to the use of a mixture comprising polyamide 6 and further containing a specific amount of polyethylene terephthalate and polyamide 6.6 for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6.

[0002] Polyamides, and especially those of the formula (–NH–(CH2)5–CO–) n Polyamide 6, characterized by its polyamide content, can be found in many materials, such as packaging, engineering plastics from automobiles, and textile filaments. The latter accounts for approximately 40% of the global market for polyamide 6. Currently, only a very small percentage of textile filaments are recycled, while it accounts for a large percentage of global CO2 emissions. Therefore, there is a need to recycle polyamide 6 from such materials. Methods for alkaline depolymerization of polyamides exist. Furthermore, the methods in the art are energy-intensive. The materials subjected to such recycling methods often contain other polymer compounds, such as polyethylene terephthalate and polyamide 6.6. However, methods known in the art for depolymerizing polyamide 6 may have only moderate tolerance to polyethylene terephthalate and sometimes also to polyamide 6.6. Therefore, there is a need for an improved method for hydrolyzing depolymerized polyamide 6, which contains polyethylene terephthalate and polyamide 6.6 in addition to polyamide 6.

[0003] Surprisingly, the method of the present invention (in which polyamide 6 is hydrolyzed and depolymerized and in which the feedstock undergoing the hydrolysis and depolymerization process contains, relative to a specific amount of the polymer compound polyethylene terephthalate and polyamide 6.6) allows for an increased yield of the valuable product, namely the monomer compound ε-caprolactam produced by the depolymerization of polyamide 6. Furthermore, the method of the present invention allows for a reduction in total energy consumption compared to known methods, thereby allowing for a reduction in CO2 footprint and cost.

[0004] Therefore, the present invention relates to a method for hydrolyzing and depolymerizing polyamide 6 contained in chemical raw material F, the method comprising:

[0005] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0006] (ii) Provide liquid aqueous flow S W ;

[0007] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U.R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E Contains ε-caprolactam;

[0008] According to (iii), the mixture to be subjected to the depolymerization conditions of polyamide 6 contains polyamide 6 and further contains a mass ratio of r S = (m PA6.6 + m PET ) / m PA6 6.6% of polyethylene terephthalate and polyamide, wherein 0.01 ≤ r S ≤ 2.5.

[0009] Preferably, according to the present invention, regarding the mass ratio r S In this case, 0.02 ≤ r S ≤ 2, more preferably 0.03 ≤ r S ≤1.9, more preferably 0.04 ≤ r S ≤ 1.8, more preferably 0.05 ≤ r S ≤ 1.75. More preferably, according to the invention, regarding the mass ratio r... S In this case, 0.05 ≤ r S ≤ 1, preferably 0.05 ≤ r S ≤ 0.5, more preferably 0.05 ≤ r S ≤ 0.15. For mass ratio r S Preferably, 0.04 ≤ r S ≤ 1, more preferably 0.04 ≤ r S ≤ 0.75, more preferably 0.04 ≤ r S ≤ 0.5.

[0010] Regarding the amounts of polyethylene terephthalate and polyamide 6.6 contained in raw material F, for the corresponding mass ratio r T = m PET / m PA6.6 Preferably,

[0011] 0.005 ≤ r T ≤ 5. More preferably, 0.01 ≤ r T ≤ 5, more preferably 0.015 ≤ r T ≤ 4, more preferably 0.02 ≤ r T ≤ 3.

[0012] According to the method of the invention, preferably, the total amount of polyamide 6 contained in the mixture to be subjected to the depolymerization conditions of polyamide 6 according to (iii) is contained in the chemical raw material F provided according to (i).

[0013] Furthermore, it is preferred that at least a portion of the amount of polyethylene terephthalate contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) is contained in the chemical raw material F provided according to (i). If only a portion of the polyethylene terephthalate is contained in the mixture provided according to (i), it is preferred that additional polyethylene terephthalate be added to the raw material after the raw material has been provided, such that for the raw material ultimately subjected to (iii), r S And r is preferred T The values ​​and ranges described above are achieved. Preferably, the total amount of polyethylene terephthalate contained in the mixture to be subjected to the depolymerization conditions of polyamide 6 according to (iii) is already contained in the chemical raw material F provided according to (i).

[0014] Furthermore, preferably, at least a portion of the amount of polyamide 6.6 contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) is contained in the chemical raw material F provided according to (i). If only a portion of the polyamide 6.6 is contained in the mixture provided according to (i), it is preferable that additional polyamide 6.6 be added to the raw material after it has been provided, such that for the raw material ultimately subjected to (iii), r S And r is preferred T The values ​​and ranges described above are achieved. Preferably, the entire amount of polyamide 6.6 contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) is already contained in the chemical raw material F provided according to (i).

[0015] Regarding the chemical raw material provided according to (i) and preferably subjected to (iii), it is preferred that at least 50 wt% of the chemical raw material F provided according to (i) consists of polyamide 6, polyamide 6.6, and polyethylene terephthalate. More preferably, 60 to 100 wt% of the chemical raw material F provided according to (i) and preferably subjected to (iii), more preferably 70 to 100 wt%, more preferably 75 to 100 wt% consists of polyamide 6, polyamide 6.6, and polyethylene terephthalate. Preferably, at least 25 wt% of the chemical raw material F consists of polyamide 6, wherein it may be preferred that at least 30 wt% or at least 40 wt% or at least 50 wt% or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt% of the chemical raw material F consists of polyamide 6.

[0016] Regarding the depolymerization conditions of polyamide 6 according to (iii), it is preferred that they include a polyamide 6 depolymerization temperature T in the range of 230°C to 330°C, more preferably in the range of 250°C to 320°C, more preferably in the range of 270°C to 310°C, such as in the range of 270°C to 280°C, or in the range of 280°C to 290°C, or in the range of 290°C to 300°C, or in the range of 300°C to 310°C. D Depolymerization temperature T D This refers to the temperature of the liquid reaction mixture during (iii). Further regarding the depolymerization conditions of polyamide 6 according to (iii), it is preferred that its...

[0017] The polyamide 6 depolymerization pressure p includes a range of 40 to 140 bar, more preferably 40 to 125 bar, more preferably 40 to 110 bar, such as a range of 40 to 55 bar, 55 to 70 bar, 70 to 85 bar, 85 to 100 bar, or 100 to 110 bar. D .

[0018] As mentioned above, the depolymerization of polyamide 6 according to (iii) is a hydrolysis method. Therefore, in terms of water content, it is preferable that the mixture to be subjected to the depolymerization conditions of polyamide 6 according to (iii) exhibits a mass ratio r W = (m PA6 + m PA6.6 +m PET ) / m H2O , where 0.01 ≤ r W ≤ 0.4, more preferably 0.05 ≤ r W ≤ 0.3, more preferably 0.1 ≤ r W ≤ 0.2.

[0019] Generally, the chemical raw materials provided according to (i) and preferably subjected to (iii), in addition to polyamide 6, polyethylene terephthalate, and polyamide 6.6, may further contain one or more other components such as at least one additional organic polymer compound, for example, at least one semi-aromatic polyamide, including one or more of polyamide 6T and polyamide 6I; at least one polyurethane; at least one polyester; at least one polyether; at least one polyvinyl chloride; at least one natural fiber material, such as wool and cotton; at least one cellulose material; at least one natural elastomer; at least one synthetic elastomer; at least one copolymer of two or more of the polymer compounds, including statistical copolymers, gradient copolymers, alternating copolymers, block copolymers, and graft copolymers; and at least one rubber material, including one or more of at least one natural rubber material and at least one synthetic rubber material. If the raw materials provided according to (i) and preferably subjected to (iii) further contain such additional organic polymer compounds, it is preferred that such additional organic polymer compounds include at least one polytetrahydrofuran. Furthermore, it is preferable that such additional organic polymer compounds consist of at least one polytetrahydrofuran.

[0020] Furthermore, the chemical raw materials provided according to (i) and preferably subjected to (iii) may further comprise one or more of at least one pigment material and at least one glass fiber material.

[0021] Preferably, according to the present invention, the mixture to be subjected to the hydrolytic depolymerization conditions of polyamide 6 is prepared without adding a polyamide 6 depolymerization catalyst such as an inorganic acid (such as one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid) and / or a zinc salt (such as zinc chloride, zinc acetate or zinc trifluoromethanesulfonate).

[0022] Generally speaking, the chemical raw material F provided by (i) can be composed of a single material or derived from several different materials; that is, it consists of w kinds of chemical materials M. j The composition, wherein j = 1..w and w ≥ 1. Further according to the invention, the chemical material M is preferably... j At least one of the following, more preferably each chemical material M j The material includes waste, preferably composed of, said waste, which preferably includes one or more of at least one textile waste and at least one engineering plastic waste, more preferably composed of, and even more preferably includes at least one textile waste, more preferably composed of. If w > 1, then the corresponding two or more materials can have different chemical compositions without any specific limitation, provided that the chemical raw materials exhibit the compositions discussed above.

[0023] Regarding the chemical raw material F provided according to (i), it is preferred that it is provided in solid form, more preferably in particulate form such as granules, wherein the particle size distribution of said particles is more preferably characterized by one or more of the following value pairs, more preferably two or more of the following value pairs, more preferably three of the following value pairs:

[0024] - D10 values ​​for particle width in the range of 0.3 to 15 mm and D10 values ​​for particle length in the range of 0.3 to 15 mm;

[0025] - D50 values ​​for particle width in the range of 0.5 to 20 mm and D50 values ​​for particle length in the range of 0.5 to 20 mm;

[0026] - D90 values ​​for particle width in the range of 0.8 to 30 mm and D90 values ​​for particle length in the range of 0.8 to 30 mm.

[0027] More preferred value pairs are, for example:

[0028] - D10 values ​​for particle width in the range of 2 to 4 mm and D10 values ​​for particle length in the range of 3.5 to 5.5 mm;

[0029] - D50 values ​​for particle width in the range of 2.5 to 4.5 mm and D50 values ​​for particle length in the range of 4 to 7 mm;

[0030] - D90 values ​​for particle width in the range of 3 to 5 mm and D90 values ​​for particle length in the range of 4.5 to 8.5 mm.

[0031] As used in this context of the invention, the term "granules" includes optionally pre-formed granules and also includes shredded fragments.

[0032] According to a first alternative of the invention, in accordance with (iii), the chemical raw material F is reacted in solid form with the liquid aqueous stream S. W Mixing. According to this alternative, a preferred method is one in which (i) further includes...

[0033] (i) Providing a chemical raw material F in solid form, wherein the raw material has a temperature below the melting point of polyamide 6;

[0034] (ii) further includes

[0035] (ii) Provide liquid aqueous flow S W S W 90 to 100% by weight is composed of water, and of which S W It has a temperature lower than the melting point of polyamide 6;

[0036] (iii) further includes

[0037] (iii) The solid chemical raw material provided according to (i) and the liquid aqueous stream S provided according to (ii) W Feed into chemical reaction unit U R In this way, a mixture is obtained, and U is made R The mixture in the mixture is subjected to temperatures including polyamide 6 at temperature T. D The depolymerization conditions of polyamide 6, where T D The temperature is higher than that of the raw material provided according to (i) and lower than that of the liquid aqueous flow S provided according to (ii). W The temperature.

[0038] According to a second alternative of the invention, providing the chemical raw material F according to (i) includes changing the chemical raw material F from a solid form to a liquid form, and wherein, according to (iii), the chemical raw material F is reacted with a liquid aqueous stream S in liquid form. W Mixing. Regarding this alternative, the method of the present invention may preferably include...

[0039] (a) Provide raw material F in solid form;

[0040] (b) In the melting unit U M The molten solid raw material F is obtained at pressure p. SM Below has temperature T SM Liquid flow S M ;

[0041] (c) Provided at pressure p sw Below has temperature T SW Liquid water flow S W ;

[0042] (d) In the pre-reaction unit U PR Lieutenant General S M With flow S W Mixing, thereby obtaining at pressure p SF Below has temperature T SF Liquid reaction feed stream S F ;

[0043] (e) Stream S F Feed into chemical reaction unit U R And make it in the chemical reaction unit U R The polyamide 6 undergoes depolymerization under the following conditions: polyamide 6 depolymerization temperature T. D and polyamide 6 depolymerization pressure p D Thus, to leave U R Water flow S E, flow S E It includes one or more decomposition products of ε-caprolactam and at least one other organic polymer compound.

[0044] According to this method, which includes steps (a) to (e), it is preferable that 0.8 ≤ T SF / T D ≤ 1.05 and 0.9 ≤ p SF / p D ≤ 1.05. Further preferably, 0.6 ≤ T SM / T SF ≤ 1.05 and 0.9 ≤ p SM / p SF ≤ 1.05. Furthermore, preferably, 0.8 ≤ T. SW / T SF ≤ 1.3 and 0.9 ≤ p SW / p SF ≤ 1.05. Further according to this method including steps (a) to (e), according to the pre-reaction unit U in (d). PR It includes a mixing unit, preferably a static mixing unit, and is preferably composed of therein. As used herein, the term "static mixing unit" refers to an arrangement of mixing elements mounted in a pipe or conduit, and operating substantially without moving parts, preferably without any moving parts at all. According to the invention, it is preferable that the mixing unit is configured for flow S M Pipes and used for flow S W A suitable pipe fitting for the tube, in which no specific mixing element is present. Furthermore, preferably, the melting unit U... M Including a kneader or extruder, more preferably an extruder, wherein even more preferably, the melting unit U M It consists of an extruder, more preferably a single-screw extruder or a twin-screw extruder, more preferably a twin-screw extruder. Furthermore, according to this method including steps (a) to (e), it is preferable that, in the melting unit U... M Downstream and reaction unit U R Upstream arrangement of filter unit U F Preferred for use from liquid flow S M A filtration unit U for separating particles with a particle size in the range of 100 to 500 micrometers, preferably in the range of 200 to 400 micrometers. F The method includes causing the liquid stream S to flow before mixing according to (d). M Through U F .

[0045] Regarding step (iii), preferably, the raw material F and the stream S are... W A mixing ratio (m) in the range of 1:1 to 20:1, preferably in the range of 2:1 to 15:1, and more preferably in the range of 5:1 to 10:1. W / kg) / (m P Mixed ( / kg), where m W It is included in S W The amount of water in and m P It is the amount of polyamide 6 contained in chemical raw material F.

[0046] Regarding the chemical reaction unit U R Preferably, it comprises z chemical reactors R i , i = 1…z, where z is in the range of 1 to 10, preferably in the range of 1 to 8, more preferably in the range of 1 to 6, more preferably in the range of 1 to 5, more preferably in the range of 1 to 4, and more preferably in the range of 1 to 3. If z > 1, then at least 2 reactors R i , Select z reactors R i It is connected in series.

[0047] The reaction mixture subjected to the depolymerization conditions of polyamide 6 in chemical reaction unit U R The total residence time is in the range of 15 to 800 minutes, preferably in the range of 30 to 600 minutes, more preferably in the range of 45 to 360 minutes, and even more preferably in the range of 60 to 240 minutes. As used in this context of the invention, the term "total residence time" refers to the total residence time in all the chemical reactors R mentioned above. i The total time spent in the area.

[0048] According to the invention, it is preferable, particularly with respect to the method as described above, including steps (a) to (e), that if z > 1, then at least two reactors R i , Select z reactors R i It is connected in series, where the flow S F Feeding to R i In the middle, where i = 1; an aqueous liquid stream S containing ε-caprolactam dissolved in water is flowed. i From reactor R i Remove from the middle and feed into reactor R i+1 In the context of i < z, and the aqueous liquid containing ε-caprolactam dissolved in water, S, is flowed... z As flow S E From reactor R z Removed from the middle; wherein in each reactor R i In the middle, under the depolymerization pressure pDi Maintain depolymerization temperature T Di , among which, independently of each other, T Di Within the range of 230°C to 330°C and p Di Within the range of 40 to 140 bar, preferably where T Di Within the range of 250°C to 320°C and p Di In the range of 40 to 125 bar, more preferably, T Di Within the range of 270°C to 310°C and p Di Within the range of 40 to 110 bar. Preferably, for z > 1, z reactors R i Arranged vertically, with R1 being the topmost reactor and R... z It is the bottom reactor, from which R i S obtained i Transferred to R by gravity, preferably solely by gravity. i+1 .

[0049] More preferably, at least one, and preferably z, reactor R i It is a stirred tank reactor, wherein each stirred tank reactor R i The reactor may preferably have 2 to 6 compartments, more preferably 2 to 5 compartments, and more preferably 2 to 4 compartments, which are independently arranged. The compartments are preferably arranged in series, more preferably in series and vertically, wherein two adjacent compartments are separated by a partition including at least one flow opening. This is included in reactor R. i The at least one compartment in the reactor may preferably include at least one stirrer, wherein preferably each reactor R i Each compartment includes at least one stirrer, wherein more preferably, each reactor R i Each compartment includes a stirrer, wherein the method includes stirring the depolymerization mixture in a given compartment for at least a portion of the time during which the compartment is subjected to depolymerization conditions.

[0050] Alternatively, regarding the specific design of the stirred tank reactor, according to the present invention, it is particularly preferred that at least one stirred tank reactor R i , Preferably each stirred tank reactor R i The reactor R has, preferably, 2 to 6 compartments, more preferably 2 to 5 compartments, and even more preferably 2 to 4 compartments, which are independently arranged, preferably in series, and more preferably in series and vertically arranged. iThe method includes at least one agitator, and two adjacent compartments are formed and separated by one or more suitable components of the agitator (such as blades included in the agitator), wherein the method includes agitating the depolymerized mixture in a given compartment for at least a portion of the time during the depolymerization conditions in the reactor compartment.

[0051] The depolymerization conditions for polyamide 6 preferably further include an aqueous depolymerization mixture in unit U R In the middle and preferred positions, in z reactors R i The more preferred total residence time t in z stirred tank reactors D The aqueous depolymerization mixture contains at least 85% by weight, preferably at least 90% by weight, more preferably at least 95% by weight, having a t in the range of 30 to 90 min. D More preferably, for z > 1, the aqueous depolymerization mixture in reactor R i The dwell time in is t Di And where 0.90 ≤ (t) Di / t Di+1 )≤ 1.10, preferably 0.95 ≤ (t) Di / t Di+1 ) ≤ 1.05.

[0052] According to the present invention, it is preferable to include the part leaving U R The flow S E Water in the appropriate form as S W At least a portion of the recirculation. Further preferably, according to this recirculation, the method further includes...

[0053] (iv) Generating a water flow S R Including making from chemical reaction unit U R The obtained stream S E —Optionally, when using S E After filtration—and hot water separation—a flow S is obtained. R ;

[0054] (v) The water flow S R At least a portion of it is used as a water-borne flow S W A portion of the feed is returned to the chemical reaction unit U. R ;

[0055] The hot water separation according to (iv) preferably includes one or more of distillation and falling film evaporation.

[0056] Preferably, according to (iv), a water flow S is generated according to (iv). R Includes, and preferably comprises, the following: from reaction unit U RThe obtained stream S E —Optionally, when using S E After filtration—distillation—to obtain stream S R The distillation is preferably carried out in a distillation column at a bottom temperature preferably in the range of 70°C to 140°C, more preferably in the range of 80°C to 120°C, more preferably in the range of 90°C to 110°C, and a top pressure preferably in the range of 0.5 to 1.5 bar, more preferably in the range of 0.7 to 1.2 bar, more preferably in the range of 0.8 to 1.1 bar, wherein the flow rate S R Obtained at the top of a distillation column. Furthermore, the distillation preferably involves condensing the overhead stream from the vapor column to obtain a liquid stream S. R According to (v), the liquid flow S R At least a portion of it is used as a water-borne flow S W A portion of the feed is returned to the chemical reaction unit U. R The liquid stream S obtained from condensation R It can preferably be divided into two streams, wherein the first stream obtained from the splitting is taken as the water flow S according to (v). W A portion of the feed is returned to the chemical reaction unit U. R The second stream feed is returned to the top of the distillation column, wherein the volume ratio of the first stream to the second stream is preferably in the range of 10:1 to 0.5:1, more preferably in the range of 7:1 to 1:1, and even more preferably in the range of 5:1 to 2:1.

[0057] More preferably, according to (iv), the aqueous flow S R In making flow S E Under U R Produced in one or more downstream stages of the process, based on this aqueous stream, a stream S containing purified ε-caprolactam is prepared. CPL This can then be appropriately recycled back into the materials value chain, such as as starting materials for the preparation of polyamide 6. The one or more downstream purification stages (which may further include one or more stages, according to which the flow S...) E The heat contained therein, when properly recovered and used, for example, to at least partially meet the heat requirements of one or more of the downstream purification stages, may include, for example, the following sequence of stages:

[0058] (A) The liquid water flow S E Passing into evaporation unit U E In, thus from S E Obtain the concentration c SL Liquid aqueous flow S of ε-caprolactam dissolved in water L , where c SL > cSR And further from S E Obtain one or more water vapor streams S V ;

[0059] (B) The water flow S L Introduced into the heat-consuming purification unit U P In, thus from S L Obtain the concentration c SCPL The flow of ε-caprolactam S CPL , where c SCPL >> c SL And further from S L Obtain one or more water-borne flows S RW U P At least a portion of the heat consumed is generated by one or more streams S V At least one of them is provided, thereby from the at least one stream S V Obtain at least one at least partially condensed aqueous flow S VW ;

[0060] (C) Transfer at least one stream S VW At least partially and including at least one stream S RW At least in part as the flow S R Recycled to the reaction unit U R .

[0061] The recycling according to (C) may preferably include

[0062] (C.1) The at least one stream S VW and at least one stream S RW Feeding to water treatment unit U W In, thus from U W Obtain at least one aqueous recirculating flow S R ;

[0063] (C.2) Place at least one water flow S R At least partially recycled to reaction unit U R .

[0064] According to (C.1) water treatment unit U W It may preferably include a water recycling unit U WR and wastewater unit U WW , where (x.1) further includes

[0065] (C.1.1) The at least one flow S VW and at least one stream S RW Feed to water recovery unit U WR In, thus from UWR Obtain at least one aqueous recirculating flow S W and at least one water-borne flow S SW ;

[0066] (C.1.2) at least one stream S SW Feed to wastewater unit U WW Thus from U WW At least one wastewater flow S is obtained WW .

[0067] According to the purification unit U of (B) P It may preferably include a hot water separation unit U WS Heat-consuming distillation unit U D and heat-consuming crystallization unit U C One or more of them, preferably hot water separation units U WS Heat-consuming distillation unit U D and heat-consuming crystallization unit U C Two or more of them, more preferably hot water separation units U WS Heat-consuming distillation unit U D and heat-consuming crystallization unit U C Among them, in U WS U D and U C At least a portion of the heat consumed in one or more of the streams S V At least one of them is provided.

[0068] Preferably, the method may include one or more of the following; more preferably, at least two or more of the following; more preferably, all of the following:

[0069] -From U WS Obtain at least one at least partially condensed aqueous flow S VW1 ;

[0070] -From U D Obtain at least one at least partially condensed aqueous flow S VW2 ;

[0071] -From U C Obtain at least one at least partially condensed aqueous flow S VW3 ;

[0072] The method further includes placing one or more S VW1 S VW2 and S VW3 Preferably two or more S VW1 S VW2 and S VW3 More preferably S VW1 SVW2 and S VW3 Feed into water treatment unit U as defined above W middle.

[0073] Preferably, flow S RW At least one of them is from U WS Obtained.

[0074] Preferably, the purification unit U P It may include a hot water separation unit U WS Heat-consuming distillation unit U D and heat-consuming crystallization unit U C The method includes containing concentration c SL The flow of ε-caprolactam S L Feeding to U WS Thus from U WS Obtain the concentration c UWS The flow of ε-caprolactam U WS , will flow S UWS Feed to distillation unit U D Thus from U D Obtain the concentration c UD The flow of ε-caprolactam S UD And will flow S UD Feed into crystallization unit U C In China, and from U C Obtain the concentration c SCPL The flow of ε-caprolactam S CPL , where c SL < c UWS < c UD < c SCPL .

[0075] Preferably, the water separation unit U WS It may include at least two hot water separation subunits U WS1 and U WS2 Preferably, two hot water separation subunits U connected in series are used. WS1 and U WS2 , in which the flow S L Feeding to U WS1 In, and among them U WS1 and U WS2 At least a portion of the heat consumed in one or more of the streams S V At least one of them is provided.

[0076] Preferably, the method may include one or more of the following, more preferably all of the following:

[0077] -From U WS1Obtain at least one at least partially condensed aqueous flow S VW11 ;

[0078] -From U WS2 Obtain at least one at least partially condensed aqueous flow S VW12 .

[0079] Preferably, at least one aqueous flow S RW1 From U WS1 Obtained, and at least one aqueous flow S RW2 From U WS2 Obtained, and in which S RW1 and S RW2 At least one of them, preferably S RW1 and S RW2 Feeding to U W middle.

[0080] Preferably, the evaporation unit U E It may include two or more evaporation sub-units, and the method includes obtaining at least two vapor streams S. V1 and S V2 , will the steam flow S V1 The steam flow S is introduced into at least one heat-consuming unit and the steam stream S is directed to the heat-consuming unit. V 2 is introduced into at least one heat-consuming unit, wherein the steam flow S V1 and S V2 They differ from each other in terms of pressure and / or temperature.

[0081] Regarding the above-mentioned flow S CPL That is, the purified ε-caprolactam stream, preferably, the stream S CPL Introduced into polyamide 6 production unit U PP This stream is used as the starting material in this unit. If needed, one or more additional streams S can be added. NCPL Additionally, U is introduced. PP The stream contains non-recycled ε-caprolactam, i.e., ε-caprolactam from conventional sources. The prepared polyamide 6 material can then preferably be passed into unit U. TP In this unit, the polyamide 6 material is used as a starting material for preparing materials containing polyamide 6, preferably textile materials containing polyamide 6. If desired, one or more additional streams S can be added. NPA6 Additionally, U is introduced. TP The stream contains non-recycled polyamide 6, i.e., polyamide 6 from conventional sources. According to U... TP The types of materials prepared in the process can also include other starting materials other than polyamide 6 flowing into the U. TP This material, preferably from U... TP The obtained textile material MT Then preferably it enters the market and remains there for a given lifespan T. MT Subsequently, the corresponding scrap materials are appropriately collected in collection unit U. TC In a preferred textile material collection unit, the waste material may optionally be appropriately introduced from the collection unit as raw material F or as part of raw material F after sorting as described herein, using the method described above.

[0082] The method of the present invention as described above can preferably be a continuous method. However, one or more method steps can be performed in a batch-type mode, and one or more steps can be performed in a semi-continuous mode.

[0083] The present invention also relates to a mass ratio r S = (m PA6.6 + m PET ) / m PA6 A mixture of polyamide 6, polyethylene terephthalate, and polyamide 6.6—where 0.01 ≤ r S ≤ 2 — Use for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6, said reaction comprising

[0084] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0085] (ii) Provide liquid aqueous flow S W ;

[0086] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E It contains ε-caprolactam.

[0087] According to the use of the invention involving reactions including (i), (ii) and (iii), all preferred features and combinations of features discussed above with respect to (i), (ii) and (iii) also apply.

[0088] Furthermore, depending on the intended use, the yield of ε-caprolactam is increased, particularly compared to the following:

[0089] (a) A mixture comprising polyamide 6 and polyethylene terephthalate, wherein the mixture does not contain polyamide 6.6; and

[0090] (b) A mixture comprising polyamide 6 and polyamide 6.6, wherein the mixture does not contain polyethylene terephthalate.

[0091] Furthermore, the present invention also relates to a method for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6, said reaction comprising:

[0092] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0093] (ii) Provide liquid aqueous flow S W ;

[0094] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E Contains ε-caprolactam;

[0095] The method includes preparing a mixture according to (iii) such that it contains a mass ratio of r S = (m PA6.6 +m PET ) / m PA6 Polyamide 6, polyethylene terephthalate and polyamide 6.6, wherein 0.01 ≤ r S ≤ 2. According to the method involving the reactions including (i), (ii) and (iii), all preferred features and combinations of features discussed above with respect to (i), (ii) and (iii) also apply.

[0096] Furthermore, according to the method described above, the yield of ε-caprolactam is increased, particularly compared to the following:

[0097] (a) A mixture comprising polyamide 6 and polyethylene terephthalate, wherein the mixture does not contain polyamide 6.6; and

[0098] (b) A mixture comprising polyamide 6 and polyamide 6.6, wherein the mixture does not contain polyethylene terephthalate.

[0099] Chemical raw materials and materials M are provided respectively. jThis may include an upstream sorting stage. In this regard, the collected waste, preferably engineering plastic waste and / or textile waste, more preferably textile waste, may be spread on a conveyor, which may be done manually and / or mechanically. Thereafter, the spread waste is sorted by composition and / or by color. Sorting may be done manually and / or optically. If optically, sorting preferably includes infrared sorting, more preferably near-infrared sorting and / or mid-infrared sorting. Optionally, prior to sorting, the waste may be subjected to a suitable metal removal step. If a metal removal step is performed, iron is preferably separated, for example, by a suitable magnetic device, and / or non-ferrous elements are preferably separated, for example, by a suitable eddy current separation device. After the sorting, the resulting waste may be subjected to further processing, such as cutting and / or milling.

[0100] The invention is further illustrated by the following set of embodiments and combinations of embodiments derived from the dependent relationships and reverse references shown. In particular, it should be noted that in each instance of reference to a series of embodiments, such as in the context of the term "method as described in any one of Embodiments 1 to 4," each embodiment in this series is intended to clearly disclose to those skilled in the art that the wording of this term should be understood by those skilled in the art to be synonymous with "method as described in any one of Embodiments 1, 2, 3, and 4." Furthermore, it should be clearly noted that the following set of embodiments represents appropriate structural portions of the general description of preferred aspects of the invention and therefore appropriately supports, but does not represent, the claims of the invention.

[0101] 1. A method for hydrolyzing and depolymerizing polyamide 6 contained in chemical feedstock F, the method comprising:

[0102] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0103] (ii) Provide liquid aqueous flow S W ;

[0104] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E Contains ε-caprolactam;

[0105] According to (iii), the mixture to be subjected to the depolymerization conditions of polyamide 6 contains polyamide 6 and further contains a mass ratio of r S = (m PA6.6 + mPET ) / m PA6 6.6% of polyethylene terephthalate and polyamide, wherein 0.01 ≤ r S ≤ 2.5.

[0106] 2. The method as described in Example 1, wherein 0.02 ≤ r S ≤ 2, preferably 0.03 ≤ r S ≤ 1.9, more preferably 0.05 ≤ r S ≤ 1.75.

[0107] 3. The method as described in Example 2, wherein 0.05 ≤ r S ≤ 1, preferably 0.05 ≤ r S ≤ 0.5, more preferably 0.05 ≤ r S ≤ 0.15.

[0108] 4. The method as described in any one of Examples 1 to 3, wherein, according to (iii), the mixture to be subjected to the polyamide 6 depolymerization conditions contains a mass ratio of r T = m PET / m PA6.6 The polyethylene terephthalate and the polyamide 6.6, wherein 0.005 ≤ r T ≤ 5.

[0109] 5. The method as described in Example 4, wherein 0.01 ≤ r T ≤ 5, preferably 0.015 ≤ r T ≤ 4, more preferably 0.02 ≤ r T ≤ 3.

[0110] 6. The method as described in Example 5, wherein 0.1 ≤ r T ≤ 3, preferably 0.2 ≤ r T ≤ 3, more preferably 0.5≤ r T ≤ 3.

[0111] 7. The method as described in any one of Examples 1 to 6, wherein,

[0112] -The total amount of polyamide 6 contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) is contained in the chemical raw material F provided according to (i);

[0113] - At least a portion, preferably all, of the polyethylene terephthalate contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) is contained in the chemical raw material F provided according to (i);

[0114] - At least a portion, preferably all of the polyamide 6.6 contained in the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii), is contained in the chemical raw material F provided according to (i).

[0115] 8. The method as described in any one of Examples 1 to 7, wherein at least 50% by weight of the chemical raw material F provided according to (i) consists of the polyamide 6, the polyamide 6.6 and the polyethylene terephthalate.

[0116] 9. The method as described in Example 8, wherein the chemical raw material F provided according to (i) comprises 60 to 100 wt%, more preferably 70 to 100 wt%, and more preferably 75 to 100 wt%, of the polyamide 6, the polyamide 6.6, and the polyethylene terephthalate.

[0117] 10. The method as described in any one of Examples 1 to 9, wherein the polyamide 6 depolymerization conditions according to (iii) include a polyamide 6 depolymerization temperature T in the range of 230°C to 330°C, preferably in the range of 250°C to 320°C, and more preferably in the range of 270°C to 310°C. D .

[0118] 11. The method as described in any one of Examples 1 to 10, wherein the polyamide 6 depolymerization conditions according to (iii) include a polyamide 6 depolymerization pressure p in the range of 40 to 140 bar, preferably in the range of 40 to 125 bar, and more preferably in the range of 40 to 110 bar. D .

[0119] 12. The method as described in any one of Examples 1 to 11, wherein the mixture to be subjected to the polyamide 6 depolymerization conditions according to (iii) exhibits a mass ratio r W = (m PA6 + m PA6.6 + m PET ) / m H2O , where 0.01 ≤ r W ≤0.4, preferably 0.05 ≤ r W ≤ 0.3, more preferably 0.1 ≤ r W ≤ 0.2.

[0120] 13. The method of any one of Examples 1 to 12, wherein the chemical raw material F provided according to (i) further comprises at least one additional polymer compound in addition to the polyamide 6, the polyamide 6.6 and the polyethylene terephthalate, said at least one additional polymer compound preferably comprising polytetrahydrofuran.

[0121] 14. The method as described in any one of Examples 1 to 12, wherein the chemical raw material F provided according to (i) is in solid form, preferably in particulate form, wherein the particle size distribution of said particles is preferably characterized by one or more of the following value pairs, more preferably two or more of the following value pairs, more preferably three of the following value pairs:

[0122] - D10 values ​​for particle width in the range of 0.3 to 15 mm and D10 values ​​for particle length in the range of 0.3 to 15 mm;

[0123] - D50 values ​​for particle width in the range of 0.5 to 20 mm and D50 values ​​for particle length in the range of 0.5 to 20 mm;

[0124] - D90 values ​​for particle width in the range of 0.8 to 30 mm and D90 values ​​for particle length in the range of 0.8 to 30 mm.

[0125] 15. The method as described in Example 14, wherein, according to (iii), the chemical raw material F is reacted with the liquid aqueous stream S in solid form. W mix.

[0126] 16. The method as described in Example 14, wherein providing the chemical raw material F according to (i) preferably involves converting the chemical raw material F from a solid form to a liquid form by subjecting it to melt extrusion, and wherein, according to (iii), the chemical raw material F is in liquid form mixed with the liquid aqueous stream S W mix.

[0127] 17. The method as described in any one of Examples 1 to 16, wherein, according to (iii), the raw material F and the stream S are... W A mixing ratio (m) in the range of 1:1 to 20:1, preferably in the range of 2:1 to 15:1, and more preferably in the range of 5:1 to 10:1. W / kg) / (m P Mixed ( / kg), where m W It is included in S W The amount of water in and m P It is the amount of polyamide 6 contained in F.

[0128] 18. The method as described in any one of Examples 1 to 17, wherein the reaction unit U R Includes z chemical reactors R i, i = 1…z, where z is in the range of 1 to 10, preferably in the range of 1 to 8, more preferably in the range of 1 to 6, more preferably in the range of 1 to 5, more preferably in the range of 1 to 4, and more preferably in the range of 1 to 3.

[0129] 19. The method as described in Example 18, wherein if z > 1, then at least two reactors R i , Select z reactors R i It is connected in series.

[0130] 20. The method as described in any one of Examples 1 to 19, wherein in the chemical reaction unit U R The total stay time is in the range of 15 to 800 minutes, preferably in the range of 30 to 600 minutes, more preferably in the range of 45 to 360 minutes, and even more preferably in the range of 60 to 240 minutes.

[0131] 21. The method of any one of Examples 1 to 20, wherein no polyamide 6 depolymerization catalyst is added in order to prepare the mixture to be subjected to the depolymerization conditions of hydrolyzed polyamide 6.

[0132] 22. The method as described in any one of Examples 1 to 21, wherein the chemical raw material F provided according to (i) is composed of w kinds of chemical materials M j Composition, where j = 1..w and w ≥ 1.

[0133] 23. The method as described in Example 22, wherein these chemical materials M i At least one of the following, more preferably each chemical material M i It includes waste materials, preferably composed of them, wherein the waste materials preferably include one or more of at least one textile waste and at least one engineering plastic waste, more preferably composed of them, and even more preferably including at least one textile waste, and even more preferably composed of them.

[0134] 24. The method as described in any one of Examples 1 to 23, wherein the method is a continuous method, a semi-continuous method, or a batch method.

[0135] 25. The method as described in any one of Examples 1 to 24, further comprising:

[0136] (iv) Generating a water flow S R Including making from the chemical reaction unit U R The obtained stream S E —Optionally, when using S E After filtration—and hot water separation—the flow S is obtained. R ;

[0137] (v) The water flow S R At least a portion of the water flow S W A portion of the feed is returned to the chemical reaction unit U. R ;

[0138] The hot water separation according to (iv) preferably includes one or more of distillation and falling film evaporation.

[0139] 26. The method as described in Example 25, wherein the aqueous flow S is generated according to (iv). R Includes, and preferably comprises, the following: from the reaction unit U R The obtained stream S E —Optionally, when using S E After filtration—distillation—the stream S is obtained. R .

[0140] 27. The method as described in Example 26, wherein distillation is carried out in a distillation column at a bottom temperature in the range of 70°C to 140°C, preferably in the range of 80°C to 120°C, more preferably in the range of 90°C to 110°C, and at a top pressure in the range of 0.5 to 1.5 bar (absolute value), preferably in the range of 0.7 to 1.2 bar (absolute value), more preferably in the range of 0.8 to 1.1 bar (absolute value), wherein the flow S R Obtained at the top of the distillation column.

[0141] 28. The method as described in Example 27, wherein distillation includes subjecting the overhead stream of the vapor tower to condensation to obtain a liquid stream S. R The liquid flow S is determined according to (v). R At least a portion of the water flow S W A portion of the feed is returned to the chemical reaction unit U. R .

[0142] 29. The method as described in Example 28, wherein the liquid stream S obtained from condensation is... R The stream is divided into two streams, where, according to (v), the first stream obtained from the split is taken as the water flow S. W A portion of the feed is returned to the chemical reaction unit U. R The second stream feed is returned to the top of the distillation column, wherein the volume ratio of the first stream to the second stream is preferably in the range of 10:1 to 0.5:1, more preferably in the range of 7:1 to 1:1, and even more preferably in the range of 5:1 to 2:1.

[0143] 30. The method as described in any one of Examples 1 to 25, wherein the aqueous flow S is generated according to (iv).R include

[0144] (A) The liquid water flow S E Passing into evaporation unit U E In, thus from S E Obtain the concentration c SL Liquid aqueous flow S of ε-caprolactam dissolved in water L , where c SL > c SR And further from S E Obtain one or more water vapor streams S V ;

[0145] (B) The water flow S L Introduced into the heat-consuming purification unit U P In, thus from S L Obtain the concentration c SCPL The flow of ε-caprolactam S CPL , where c SCPL >> c SL And further from S L Obtain one or more water-borne flows S RW U P At least a portion of the heat consumed is generated by one or more streams S V At least one of them is provided, thereby from the at least one stream S V Obtain at least one at least partially condensed aqueous flow S VW ;

[0146] (C) Transfer at least one stream S VW At least partially and including at least one stream S RW At least in part as the flow S R Recycled to the reaction unit U R .

[0147] 31. S that can be obtained or acquired by the method as described in Example 30 CPL Used for the preparation of one or more polymers and polymer products; or

[0148] A method for preparing one or more polymers and polymer products, said method comprising using S that can be obtained or acquired by the method as described in Example 30. CPL As starting material.

[0149] 32. The use or method as described in Example 31, wherein the polymer, or the polymer product, or the polymer and the polymer product are in the form of at least one of granules, strands, rods, plates, tubes, foils, layers, films, sheets, fibers, filaments, coatings, extruded articles, molded articles, soft foams, semi-rigid foams and rigid foams.

[0150] 34. The use or method as described in any one of Examples 31 to 33, wherein the polymer, or the polymer product, or the polymer and the polymer product are one or a part of one of the following:

[0151] - Automotive parts, preferably cylinder head covers, engine covers, housings for turbocharged air coolers, turbocharged air cooler baffles, intake pipes, intake manifolds, connectors, gears, fan impellers, coolant tanks, housings or housing parts for heat exchangers, coolant coolers, turbocharged air coolers, thermostats, water pumps, radiators, fasteners for electric vehicles or battery system parts, dashboards, steering column switches, seats, headrests, center consoles, transmission components, door modules, automotive exterior trim for A-pillar, B-pillar, C-pillar, or D-pillar covers, spoilers, door handles, exterior mirrors, windshield wipers, windshield wiper protective housings, decorative grilles, cover strips, roof racks, window frames, sunroof frames, antenna panels, headlights, taillights, airbags, and / or seat cushions;

[0152] - Fabrics, clothing, preferably shirts, trousers, sweaters, boots, shoes, shoe soles, bodysuits and / or jackets;

[0153] - Electrical components, preferably electrical parts, passive electronic parts, active electronic parts, printed circuit boards, housing parts, foils, circuits, switches such as microswitches, plugs, sockets, distributors, relays, resistors, capacitors, inductors, spools, lamps, diodes such as LEDs, transistors, connectors, regulators, integrated circuits (ICs), processors, controllers, memory, sensors, microbuttons, semiconductors, such as reflector housings for light-emitting diodes, fasteners for electrical and / or electronic components, spacers, bolts, strips, slide rails, screws, nuts, membrane hinges, snap hooks (buckles) and / or spring tongues;

[0154] - Consumer and / or pharmaceutical products, preferably tennis strings, climbing ropes, bristles, brushes, artificial turf, 3D printed filaments, lawnmowers, zippers, Velcro, paper machine netting, extrusion coatings, fishing lines, fishing nets, marine pipelines and ropes, vials, syringes, ampoules, bottles, sliding elements, spindle nuts, chain conveyors, sliding bearings, rollers, wheels, gears, ring gears, screws and spring dampers, hoses, pipes, cable sheaths, sockets, switches, cable ties, fan impellers, carpets, boxes and / or bottles for cosmetics, mattresses, cushions, and insulating materials;

[0155] - Packaging for the food industry, preferably single-layer and / or multi-layer blown film, cast film (single-layer and / or multi-layer), biaxial stretch film, or laminated film.

[0156] 35. The use or method as described in any one of Examples 31 to 34, wherein the polymer, or the polymer product, or the polymer and the polymer product contain S CPL Available or obtainable polyamide 6, the S CPL The amount of the substance can be obtained or acquired by the method as described in Example 30, wherein the amount is 1 wt% or more, preferably 2 wt% or more, more preferably 5 wt% or more, more preferably 15 wt% or more, more preferably 30 wt% or more, more preferably 40 wt% or more, more preferably 60 wt% or more, more preferably 80 wt% or more, more preferably 90 wt% or more, more preferably 95 wt% or more; and / or the amount is 100 wt% or less, preferably 95 wt% or less, more preferably 90 wt% or less, more preferably 50 wt% or less, more preferably 25 wt% or less, more preferably 10 wt% or less.

[0157] 36. Contains a mass ratio r S = (m PA6.6 + m PET ) / m PA6 A mixture of polyamide 6, polyethylene terephthalate, and polyamide 6.6—where 0.01 ≤ r S ≤ 2 — Use for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6, said reaction comprising

[0158] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0159] (ii) Provide liquid aqueous flow S W ;

[0160] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) WThe mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E It contains ε-caprolactam.

[0161] 37. The use as described in Example 36, wherein the yield of ε-caprolactam is increased compared to the following:

[0162] (a) A mixture comprising polyamide 6 and polyethylene terephthalate, wherein the mixture does not contain polyamide 6.6; and

[0163] (b) A mixture comprising polyamide 6 and polyamide 6.6, wherein the mixture does not contain polyethylene terephthalate.

[0164] 38. A method for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6, said reaction comprising:

[0165] (i) Provide chemical raw material F, wherein at least 25% by weight of chemical raw material F consists of polyamide 6;

[0166] (ii) Provide liquid aqueous flow S W ;

[0167] (iii) Preparation comprising raw material F provided according to (i) and liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E , flow S E Contains ε-caprolactam;

[0168] The method includes preparing a mixture according to (iii) such that it contains a mass ratio of r S = (m PA6.6 +m PET ) / m PA6 Polyamide 6, polyethylene terephthalate and polyamide 6.6, wherein 0.01 ≤ r S ≤ 2.

[0169] 39. The method as described in Example 38, wherein the yield of ε-caprolactam is increased compared to the following:

[0170] (a) A mixture comprising polyamide 6 and polyethylene terephthalate, wherein the mixture does not contain polyamide 6.6; and

[0171] (b) A mixture comprising polyamide 6 and polyamide 6.6, wherein the mixture does not contain polyethylene terephthalate.

[0172] In embodiment 35, the appropriate quantities are preferably determined based on identity preservation and / or segregation and / or balance of quality and / or book and claim chain of custody models, more preferably based on balance of quality, and even more preferably based on the International Sustainability and Carbon Certification (ISCC) standard.

[0173] With regard to Examples 31 to 35, the preparation of polymers, polymer products, or polymers and polymer products may include one or more synthetic steps and may be carried out by conventional synthesis and techniques known to those skilled in the art. Examples of the synthetic steps are described in “Industrial Organic Chemistry”, Volume 3, Wiley-VCH, 1997; ISBN: 978-3-527-28838-0; “Kunststoffhandbuch”, Volume 11 of 17 sub-volumes, Carl Hanser Verlag, especially Volume 6, “Polyamide”, 1st edition, 1966; “Injection Molding Reference Guide”, 4th edition, CreateSpace, 2011, ISBN: 978-1466407824; WO 2008 / 155271 A1 and WO2013 / 139827 A1, each of which is incorporated herein by reference.

[0174] In the context of this invention, the term "X is one or more of A, B, and C," where X is a given feature and each of A, B, and C represents a specific implementation of said feature, should be understood to disclose that X is A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. In this regard, it should be noted that those skilled in the art can convert the above abstract terms into concrete examples, for example, where X is a chemical element and A, B, and C are specific elements such as Li, Na, and K, or X is a temperature and A, B, and C are specific temperatures such as 10°C, 20°C, and 30°C. In this regard, it should be further noted that those skilled in the art can extend the above terms to less specific implementations of the feature, such as "X is one or more of A and B," which discloses that X is A, or B, or A and B, or extend them to more specific implementations of the feature, such as "X is one or more of A, B, C, and D," which discloses that X is A, or B, or C, or D, or A and B, or A and C, or A and D, or B and C, or B and D, or C and D, or A and B and C, or A and B and D, or B and C and D, or A and B and C and D.

[0175] As used in this article, the term "bar" refers to "abs", which is bar (absolute value), and is sometimes also called "bara".

[0176] As used herein, the term "textile materials" encompasses both textile and non-textile raw materials processed into linear, planar, and three-dimensional structures by various methods. It includes linear textile structures produced from them, such as yarns, twisted yarns, and ropes; sheet-like textile structures, such as woven fabrics, knitted fabrics, braids, stitch-knitted fabrics, nonwovens, and felts; and three-dimensional textile structures, i.e., bulk structures, such as textile hoses, stockings, or textile semi-finished products; and further includes those finished products made from the aforementioned materials through assembly, unassembly, and / or other operations to reach a marketable state for forward delivery to processors, traders, or end consumers.

[0177] The term “textile waste” encompasses textile materials as defined above, whose inherent value has been consumed from the perspective of their current owner, and therefore are scrap materials for said owner.

[0178] As used herein, the term "engineering plastics" refers to high-performance plastic grades that possess physical properties that enable them to be used long-term in structural applications, over a wide temperature range, under mechanical stress, and in challenging chemical and physical environments, such as those used to manufacture plastic parts that replace traditional engineering materials like metals and ceramics. Engineering plastics are particularly suitable for the manufacture of mechanical parts in several industries, such as automotive, medical, electrical and electronics, aerospace, construction, and consumer goods.

[0179] As used herein, the term "engineering plastic waste" encompasses engineering plastic materials as defined above, whose inherent value has been consumed from the perspective of their current owner, and therefore are end-of-life materials for said owner.

[0180] Preferred aspects of the invention are further illustrated in the examples described below. Example

[0181] Example 1: Depolymerization reaction

[0182] Raw material F, consisting of polyamide 6 (PA6), polyamide 6.6 (PA6.6), and polyethylene terephthalate (PET), was prepared according to the weight percentages shown in Tables 1, 2, and 3 of Example 2. These raw materials were then subjected to hydrolytic depolymerization in an autoclave, wherein the depolymerization mixture consisted of the respective raw materials and water, wherein the mass ratio of the raw materials to water was m. F : m H2O The ratio is 1:10. After feeding the mixture into the autoclave, the autoclave is sealed and heated to the corresponding temperatures T shown in Tables 1, 2, and 3 below. D Then the temperature T D Maintain Δt as indicated in the table. D .

[0183] Heating to the stated temperature is carried out at a heating ramp of 30 to 70 K / h. At Δt D The resulting reaction mixture was then cooled in an autoclave at a cooling ramp of 10 to 100 K / h. The resulting reaction mixture was then removed from the autoclave and sampled by a probe and subjected to GC analysis, yielding the results (yields) shown in Tables 1, 2, and 3.

[0184] The yields given in the table are calculated by dividing the mass of ε-caprolactam monomer contained in the reaction mixture obtained from depolymerization by the mass of polyamide 6 contained in the feedstock to be depolymerized.

[0185] Example 2: Examples and Comparative Examples of the Invention

[0186] The experiments shown in Tables 1, 2 and 3 below were conducted as described in Example 1 above.

[0187] Table 1

[0188] Changes in the chemical composition of raw material F

[0189]

[0190] ) CPL = ε-caprolactam monomer

[0191] As shown in Table 1 above, it was unexpectedly found that, at a constant content of PA6, the yield of the valuable product ε-caprolactam monomer was maximized if feedstock F (#2) contained both PA6.6 and PET, compared to feedstocks containing only PA6.6 (#1) or only PET (#2) in addition to PA6.

[0192] Table 2

[0193] Changes in the chemical composition of raw material F

[0194]

[0195] ) CPL = ε-caprolactam monomer

[0196] As shown in Table 2 above, it was unexpectedly found that although the PA6 content of #4 increased compared to #1 in Table 1, and although the PA6 content of #5 increased compared to #3 in Table 1, the yield of the valuable product ε-caprolactam monomer still had the highest value if both PA6.6 and PET were included in feedstock F (#2) with a lower PA6 content.

[0197] Table 3

[0198] T D Changes

[0199]

[0200] ) CPL = ε-caprolactam monomer

[0201] According to Table 3 above, parameter T D Based on the favorable raw material F according to #2, it was unexpectedly found that there is a temperature range in which the yield of the valuable product ε-caprolactam monomer shows excellent values.

[0202] The GC analysis measurements according to the present invention are performed as follows:

[0203] For GC analysis of ε-caprolactam purity, samples were prepared in deionized water at a concentration of approximately 200 mg / mL. Analysis was performed on a standard GC instrument equipped with a split / splitless injector and FID. The injection volume was 1 µL, with a split ratio of 15:1. The injector temperature was 250°C. The instrument was operated in constant pressure mode at 14.5 psi (approximately 1 bar), using nitrogen as the carrier gas. Separation was performed on a Wax 52 CB column (50 m x 0.32 mm, 1.2 µm) from Agilent Technologies. The temperature program began with a ramp from 80°C to 185°C at a heating rate of 7°C / min, with a hold time of 30 min at 185°C. A second ramp was performed from 185°C to 200°C at a heating rate of 7°C / min, with a hold time of 5 min at 200°C. The detector (flame ionization detector, FID) temperature is 250°C. Purity value Ω GC The assessment is based on the area % distribution, which is corrected for water content determined by the Karl Fischer method.

Claims

1. A process for hydrolytic depolymerization of polyamide 6 comprised in a chemical feedstock F, the process comprising (i) providing the chemical feedstock F, wherein at least 25 wt-% of the chemical feedstock F consists of the polyamide 6; (ii) providing a liquid aqueous stream S W ; (iii) Preparation comprising the raw material F provided according to (i) and the liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E The stream S E Contains ε-caprolactam; According to (iii), the mixture to be subjected to the depolymerization conditions of polyamide 6 contains polyamide 6 and further contains a mass ratio of r S = (m PA6.6 + m PET ) / m PA6 6.6% of polyethylene terephthalate and polyamide, wherein 0.01 ≤ r S ≤ 2.

5.

2. The method of claim 1, wherein, 0.02 ≤ r S ≤ 2, preferably 0.03 ≤ r S ≤ 1.9, more preferably 0.05 ≤ r S ≤ 1.

75.

3. The method of claim 1 or 2, wherein, According to (iii), the mixture to be subjected to polyamide 6 depolymerization conditions comprises a mass ratio r T = m PET / m PA6.6 of the polyethylene terephthalate and the polyamide 6.6, wherein 0.005 ≤ r T ≤ 5; preferably 0.01 ≤ r T ≤ 5, more preferably 0.015 ≤ r T ≤ 4, more preferably 0.02 ≤ r T ≤ 3.

4. The method of any one of claims 1 to 3, wherein, at least 50 wt-%, preferably 60 to 100 wt-%, more preferably 70 to 100 wt-%, more preferably 75 to 100 wt-% of the chemical feedstock F provided according to (i) consists of the polyamide 6, the polyamide 6.6 and the polyethylene terephthalate.

5. The method of any one of claims 1 to 4, wherein, The polyamide 6 depolymerization conditions according to (iii) comprise a polyamide 6 depolymerization temperature T in the range of 230 °C to 330 °C, preferably in the range of 250 °C to 320 °C, more preferably in the range of 270 to 310 D and further comprise a polyamide 6 depolymerization pressure p in the range of 40 to 140 bar, preferably in the range of 40 to 125 bar, more preferably in the range of 40 to 110 bar D .

6. The method of any one of claims 1 to 5, wherein, The mixture to be subjected to polyamide 6 depolymerization conditions according to (iii) exhibits a mass ratio r W = (m PA6 + m PA6.6 + m PET ) / m H2O , wherein 0.01 < r W < 0.4, preferably 0.05 < r W < 0.3, more preferably 0.1 < r W < 0.2; wherein according to (iii), the chemical feedstock F is mixed with the liquid aqueous stream S W in solid form, or wherein (i) comprises changing the chemical feedstock F from solid form to liquid form, preferably by subjecting the chemical feedstock F to melt extrusion, and wherein according to (iii), the chemical feedstock F is mixed with the liquid aqueous stream S W in liquid form; wherein according to (iii), the feedstock F and the stream S W Preferably, the mixing ratio (m W / kg) / (m P / kg) is in the range of 1 : 1 to 20 : 1, more preferably in the range of 2 : 1 to 15 : 1, more preferably in the range of 5 : 1 to 10 : 1, wherein m W is the amount of water contained in S W and m P is the amount of polyamide 6 contained in F.

7. The method of any one of claims 1 to 6, wherein, The total residence time in this chemical reaction unit U R ranges from 15 to 800 minutes, preferably from 30 to 600 minutes, more preferably from 45 to 360 minutes, more preferably from 60 to 240 minutes.

8. The method of any one of claims 1 to 7, wherein, According to (i), the chemical raw material F is composed of w kinds of chemical materials M j Composition, where j = 1..w and w ≥ 1, where these chemical materials M j At least one of the following, preferably each chemical material M j It includes waste materials, preferably composed of them, wherein the waste materials preferably include one or more of at least one textile waste and at least one engineering plastic waste, more preferably composed of them, and even more preferably including at least one textile waste, and even more preferably composed of them.

9. The process of any one of claims 1 to 8, further comprising (iv) producing an aqueous stream S R comprising subjecting the stream S R obtained from the chemical reaction unit U E to a filtration, optionally after subjecting S E to a thermal water separation, thereby obtaining the stream S R ; (v) feeding at least a part of the aqueous stream S R as part of the aqueous stream S W back to the chemical reaction unit U R ; wherein the hot water separation according to (iv) preferably comprises one or more of distillation and falling film evaporation.

10. The method of claim 9, wherein, According to (iv) producing the aqueous stream S R comprising, preferably consisting of, subjecting the stream S R obtained from the reaction unit U E — optionally after subjecting S E to filtration— distillation, thereby obtaining the stream S R .

11. The method of claim 10, wherein, The distillation is carried out in a distillation column at a column bottom temperature in the range of 70 °C to 140 °C, preferably in the range of 80 °C to 120 °C, more preferably in the range of 90 °C to 110 °C, and at a column head pressure in the range of 0.5 to 1.5 bar (abs), preferably in the range of 0.7 to 1.2 bar (abs), more preferably in the range of 0.8 to 1.1 bar (abs), wherein the stream S R is obtained at the top of the distillation column, wherein the distillation preferably comprises subjecting the vaporous column head stream to condensation, thereby obtaining a liquid stream S R , wherein at least a portion of the liquid stream S R is fed back to the chemical reaction unit U W as part of the aqueous stream S R according to (v).

12. The method of any one of claims 1 to 9, wherein, According to (iv) producing the aqueous stream S R comprising (A) passing the liquid aqueous stream S E into an evaporation unit U E , thereby obtaining from S E a liquid aqueous stream S SL containing ε-caprolactam dissolved in water, at a concentration c L , wherein c SL > c SR , and further obtaining from S E one or more aqueous vapor streams S V ; (B) passing the aqueous stream S L into a heat consuming purification unit U P , thereby obtaining from S L a stream S SCPL containing ε-caprolactam in a concentration c CPL , wherein c SCPL > c SL , and further obtaining from S L one or more aqueous streams S RW , wherein at least a part of the heat consumed in U P is provided by at least one of the one or more streams S V , thereby obtaining from the at least one stream S V at least one at least partially condensed aqueous stream S VW ; (C) at least one stream S VW at least partly and at least one stream S RW at least partly as the stream S R recycled to the reaction unit U R .

13. S obtainable or obtained by the method of claim 12 CPL Use for the preparation of one or more of the polymers and polymer products, wherein, The polymer, or the polymer product, or the polymer and the polymer product is in the form of at least one of a pellet, a strand, a rod, a plate, a tube, a foil, a layer, a film, a sheet, a fiber, a filament, a coating, an extruded article, a molded article, a flexible foam, a semi-rigid foam, and a rigid foam; and wherein the polymer, or the polymer product, or the polymer and the polymer product comprises polyamide 6 and, optionally, at least one additional polymer compound, said polyamide 6 being at least partially derived from S CPL is obtainable or obtained, said S CPL is obtainable or obtained by the method as claimed in claim 12, wherein the at least one additional polymer compound preferably comprises one or more of: at least one polyamide 6.6; at least one semi-aromatic polyamide comprising one or more of polyamide 6T and polyamide 6I; at least one polyethylene terephthalate; at least one polyurethane; at least one polyester; at least one polyether; at least one polyvinyl chloride; at least one natural fiber material, such as wool and cotton; at least one cellulosic material; at least one natural elastomer; at least one synthetic elastomer; at least one copolymer of two or more of the polymeric compounds, including statistical copolymers, gradient copolymers, alternating copolymers, block copolymers, and graft copolymers; and at least one rubber material, including one or more of at least one natural rubber material and at least one synthetic rubber material.

14. The use of claim 13, wherein, the polymer, or the polymer product, or the polymer and the polymer product is part of one or of one of the following: - an automotive part, preferably a cylinder head cover, an engine cover, a housing for a charge air cooler, a charge air cooler baffle, an intake pipe, an intake manifold, a connector, a gear wheel, a fan wheel, a cooling water tank, a housing or a housing part for a heat exchanger, a coolant cooler, a charge air cooler, a thermostat, a water pump, a radiator, a fastening part for an electric car or a part of a battery system, an instrument panel, a steering column switch, a seat, a headrest, a center console, a transmission part, a door module, an automotive exterior for an A-pillar, B-pillar, C-pillar or D-pillar cover, a spoiler, a door handle, an outside mirror, a windscreen wiper, a windscreen wiper protection housing, a decorative grating, a cover strip, a roof rack, a window frame, a sunroof frame, an antenna panel, a headlight, a tail light, an airbag, and / or a seat cushion; - a cloth, a garment, preferably a shirt, trousers, a pullover, boots, shoes, a shoe sole, tights and / or a jacket; - an electrical part, preferably an electrical component, an electronic passive component, an electronic active component, a printed circuit board, a housing component, a foil, a wire, a switch such as a micro switch, a plug, a socket, a distributor, a relay, a resistor, a capacitor, an inductor, a bobbin, a lamp, a diode such as an LED, a transistor, a connector, a regulator, an integrated circuit (IC), a processor, a controller, a memory, a sensor, a micro button, a semiconductor, a reflector housing, for example for a light emitting diode, a fastener for electrical and / or electronic components, a spacer, a bolt, a strip, a slide-in rail, a screw, a nut, a film hinge, a snap hook (snap) and / or a spring tongue; - consumer and / or pharmaceutical products, preferably tennis strings, climbing ropes, brush hairs, brushes, artificial turf, 3D-printed filaments, lawnmowers, zippers, nylon fasteners, paper machine clothing, extrusion coatings, fishing lines, fishing nets, offshore pipelines and ropes, vials, syringes, ampoules, bottles, sliding elements, spindle nuts, chain conveyors, plain bearings, rollers, wheels, gears, rollers, ring gears, screws and spring dampers, hoses, pipes, cable sheaths, sockets, switches, cable ties, fan wheels, carpets, boxes and / or bottles for cosmetics, mattress, cushion, insulation materials; - packaging for the food industry, preferably single- and / or multi-layer blown films, cast films (single- and / or multi-layer), biaxially stretched films, laminated films.

15. Includes mass ratio r S = (m PA6.6 + m PET ) / m PA6 A mixture of polyamide 6, polyethylene terephthalate, and polyamide 6.6—where 0.01 ≤ r S ≤ 2 — Use for increasing the yield of ε-caprolactam in the depolymerization reaction of hydrolyzed polyamide 6, said reaction comprising (i) providing a chemical feedstock F, wherein at least 25 weight-% of the chemical feedstock F consists of polyamide 6; (i) providing a chemical feedstock F, wherein at least 25 weight-% of the chemical feedstock F consists of polyamide 6; (ii) providing a liquid aqueous stream S W ; (iii) Preparation comprising the raw material F provided according to (i) and the liquid aqueous stream S provided according to (ii) W The mixture, and the mixture is reacted in chemical reaction unit U. R The polyamide 6 is subjected to depolymerization conditions to obtain the product leaving U R Water flow S E The stream S E It contains ε-caprolactam.

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