A method for producing a multi-component outdoor equipment recycled low-melt filament

Abstract

The present application belongs to the technical field of low-melting-point polyester preparation, and relates to a preparation method of a multi-component recycled low-melting-point filament for outdoor equipment. First, waste PET is mixed with polyamide 6 esterification product, and then the mixture is subjected to melt depolymerization through a double-screw extruder. Then, the depolymerized melt is transported to a reactor, terephthalic acid glycol ester is added to the reactor, and homogenization is performed, followed by a polycondensation reaction to obtain a recycled low-melting-point polyester. Finally, the recycled low-melting-point polyester is used as a skin layer, and polyamide 6 or polyamide 66 is used as a core layer, and a multi-component recycled low-melting-point filament for outdoor equipment is prepared through skin-core composite spinning. In the present application, polyamide 6 esterification product with a certain molecular weight is obtained through hydrolysis ring-opening-end group esterification modification design, and is used as a depolymerization agent and as a part of the molecular chain of the low-melting-point copolyester. By utilizing the similar compatibility of the polyamide segment, the problem of easy peeling of the skin-core interface caused by the incompatibility of the polyamide core layer and the low-melting-point polyester skin layer in kinetics and thermodynamics is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-melting-point polyester preparation, and relates to a preparation method of a multi-component recycled low-melting-point filament for outdoor equipment. BACKGROUND

[0002] Low-melting-point polyester is a kind of polyester material with significantly reduced melting temperature through molecular structure design. Its melting point is usually controlled between 80-180℃, which is much lower than that of conventional polyester, while retaining excellent mechanical properties, chemical stability and processability of the polyester family. The preparation technology mainly includes copolymerization modification, chain segment disordering and precise control of molecular weight to destroy the crystalline integrity and thus realize low-temperature melting. This kind of material has wide application in composite fibers (such as skin-core structure hot-bonding fibers), hot melt adhesives, powder coatings, plastic compatibilizers and green recycling fields. Its core advantage lies in low-temperature processability: it can reduce energy consumption and avoid damage to heat-sensitive components at high temperature. With the increasing pursuit of comfort, people are increasingly pursuing comfort in textiles. Low-melting-point polyester, as a key bonding material for outdoor products, is uniformly distributed in the product, but the skin-core material composed of polyester itself has poor flexibility, and after bonding, it is more likely to be fixed and cured, affecting the comfort and flexibility of the product.

[0003] Polyamide, as a polymer composed of aliphatic flexible chains, has the characteristics of skin-friendly and moisture absorption, and can be used as the core layer of low-melting-point skin-core composite fibers in combination with low-melting-point polyester. However, polyester and polyamide are not compatible in terms of thermodynamics, and the two components are prone to peeling, which leads to misalignment of the skin-core composite fibers and causes uneven bonding due to skin layer rupture. Most current patents add amphiphilic components between polyester and polyamide, such as the component disclosed in patent CN202311324322.7 to increase the interfacial bonding force of polyester and polyamide; or directly prepare filament products as in patent CN200780007364.0 and the like to reduce the peeling phenomenon by increasing continuity.

[0004] With the increasing application of green and environmentally friendly polymers, low-melting-point polyester as a skin layer material also has more and more copolymer elements. The current disclosed technology for preparing recycled low-melting-point polyester is mainly carried out in two steps. First, the polyester is alcoholized and depolymerized into small molecules, and after purification, a low-melting-point modifying component is added for copolymerization. For example, patents CN201911005873.0 and CN201310091292.X disclose that the product is first alcoholized, then purified and separated, and then used as a raw material for copolymerization with a low-melting-point modifying component.

[0005] Patent CN202310493611.3 discloses a preparation method of mixed regenerated low-melting-point copolyester. First, an oligomer is prepared by alcoholysis, and then a depolymerization component is added for copolymerization. The copolymerization modification during the regeneration process can prepare low-melting-point polyester. However, there are still differences between low-melting-point polyester and conventional polyester. The melt strength of low-melting-point polyester is weaker than that of conventional polyester, and peeling and other situations are more likely to occur during processing.

[0006] Therefore, it is of great significance to study a low-melting-point copolyester with a polyamide segment, realize composite processing with polyamide materials, and ensure the stability of processing and application. SUMMARY

[0007] The purpose of the present application is to solve the problems existing in the prior art and provide a preparation method of multi-component regenerated low-melting-point filament for outdoor equipment.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A preparation method of multi-component regenerated low-melting-point filament for outdoor equipment, first, waste PET is mixed with polyamide 6 esterification product, then the mixture is melted and depolymerized by a double screw, then the depolymerized melt is transported to a reactor, terephthalic acid glycol ester is added to the reactor and homogenized, and then a polycondensation reaction is carried out to obtain a regenerated low-melting-point polyester. Finally, the regenerated low-melting-point polyester is used as a skin layer, and polyamide 6 or polyamide 66 is used as a core layer. The multi-component regenerated low-melting-point filament for outdoor equipment is prepared by skin-core composite spinning.

[0010] The molecular structure of the polyamide 6 esterification product is as follows:

[0011] ;

[0012] Wherein, n≤6, x is 1~2.

[0013] As a preferred technical scheme:

[0014] The preparation process of the polyamide 6 esterification product is as follows: first, caprolactam and diacid are hydrolyzed to prepare a polyamide 6 segment with a polymerization degree of ≤6, and then the polyamide 6 segment is esterified to obtain the polyamide 6 esterification product.

[0015] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the molar ratio of caprolactam to dibasic acid is 4-6:1, and the ratio is set in this range to ensure that the molecular weight of the subsequent polyamide 6 segment is in the given range, the amount of water as the ring-opening agent is 2-3% of the mass of caprolactam; the ring-opening temperature is 200-220°C, the pressure is 0.2-0.4 MPa, and the time is 2-3 h; and the number average molecular weight of the polyamide 6 segment is 500-800 g / mol.

[0016] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the polyamide 6 segment with carboxyl groups at both ends is esterified and modified by adding a dihydric alcohol for esterification, the esterification is atmospheric esterification (i.e. under standard atmospheric pressure conditions), the esterification temperature is 230-240°C, and the esterification time is 1-2 h; and the molar ratio of the dihydric alcohol to the dibasic acid is 2.1-2.2:1.

[0017] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the dibasic acid is glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid, and the dihydric alcohol is ethylene glycol, propylene glycol, butanediol or pentanediol.

[0018] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the waste PET is polyester waste silk, polyester waste cloth or polyester-containing waste textiles; the amount of polyamide 6 ester is 5-10% of the mass of the waste PET, the depolymerization temperature is 250-270°C, the depolymerization time is 5-10 min, and the polymerization degree of the depolymerization product is 10-15.

[0019] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the amount of terephthalic acid ethylene glycol ester added is 10-15% of the total mass of substances in the reactor; the homogenization temperature is 240-260°C, and the homogenization time is 10-20 min; and the polycondensation temperature is 260-280°C, and the vacuum degree during polycondensation is <200 Pa.

[0020] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the intrinsic viscosity of the regenerated low-melting-point polyester is 0.75-0.85 dl / g, and the melting point is 120-140°C.

[0021] The preparation method of the regenerated low-melting-point filament for multi-component outdoor equipment as described above, the relative viscosity of the polyamide 6 or polyamide 66 is 2.4-2.8; the process parameters of the skin-core composite spinning are as follows: the core layer melting temperature is 280-300°C, the skin layer melting temperature is 200-220°C, the skin-core composite ratio is 5:5 or 4:6, the cooling is performed by ring blowing air cooling, the cooling air temperature is 18-25°C, the winding speed is 3000-3500 m / min, and the draft ratio is 1.1-1.4.

[0022] The preparation method of the multi-component recycled low-melting-point filament for outdoor equipment as described above, the linear density of the multi-component recycled low-melting-point filament for outdoor equipment is 240-280 dtex, the breaking strength is 2.0-3.0 cN / dtex, the breaking elongation is 105±2.0%, the boiling water shrinkage is 45±3%, and the breaking strength variation coefficient is ≤3.5%.

[0023] Inventive mechanism:

[0024] In view of the problem that the skin-core interface is prone to peeling when a flexible polyamide is used as a core layer of a sheath-core composite fiber to prepare a low-melting-point filament, because polyamide and polyester are incompatible in kinetics and thermodynamics, the polyamide 6 segment is designed to have a hydroxyl structure at both ends, thereby playing the roles of depolymerization agent and copolymerization modifier in the preparation process of the recycled low-melting-point polyester. The polyamide 6-based depolymerization agent is efficiently depolymerized through a screw reactor and added into the system as a copolymerization modifier component in one step, and other copolymerization monomers are added during the mixing and homogenization process, so that the depolymerization-functional copolymerization integrated continuous production is finally realized. In the depolymerization process, the polyamide 6 segment is uniformly distributed in the polyester segment, destroying the regularity thereof, thereby reducing the melting point and enhancing the bonding force between the recycled low-melting-point polyester and the polyamide core layer, effectively meeting the flexibility requirement of the fiber.

[0025] In the application, the polyamide 6 segment with a specific molecular weight is used as a depolymerization agent, the end hydroxyl group thereof is used for controllable depolymerization of polyester in a screw, and the low-melting-point polyester containing the polyamide segment is finally prepared by adding the depolymerization agent in proportion and then homogenizing and copolymerizing with a functional copolymerization component. The method realizes integrated process design of depolymerization and copolymerization. The polyamide 6 segment is added in the depolymerization stage, so that the polyester molecular chain is "cut", which is beneficial to the preparation of the low-melting-point polyester and the uniform copolymerization of the polyamide 6 segment in the polyester, thereby significantly improving the interfacial bonding force between the polyamide 6 segment and the polyamide core layer.

[0026] Beneficial effects:

[0027] (1) The preparation method of the multi-component recycled low-melting-point filament for outdoor equipment provided by the application obtains the polyamide 6 esterate with a certain molecular weight through hydrolysis ring-opening-esterification modification design, which can be used as a low-melting-point modifier, a depolymerization agent, and a segment structure similar to the core layer polyamide component, so that the purpose of adding multiple effects at one time is achieved, and the problem that the polyamide and polyester are incompatible in kinetics and thermodynamics and the skin-core interface is prone to peeling is solved.

[0028] (2) The preparation method of the multi-component outdoor equipment recycled low-melting point filament of the application, the polyamide 6 segment is added in the depolymerization stage, which can "chop" the polyester molecular chain, is beneficial to the preparation of low-melting point polyester and the uniform copolymerization of the polyamide 6 segment in the polyester, thereby significantly improving the interfacial bonding force with the polyamide core layer.

[0029] (3) The preparation method of the multi-component outdoor equipment recycled low-melting point filament of the application, the low-melting point polyester containing the polyamide 6 segment can form good interfacial bonding force with polyamide 6 or polyamide 66 or other polyamide materials (PA56, etc.), has wide application processing range and strong controllability of product flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The polyamide 6 esterification product is 1 H-NMR spectrum. DETAILED DESCRIPTION

[0031] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope defined by the appended claims of the application.

[0032] The test methods involved in the performance indicators in the examples and comparative examples of the application are as follows:

[0033] Intrinsic viscosity: tested according to the capillary viscometer method in GB / T 14190-2017 Test methods for fiber grade polyester chip (PET).

[0034] Breaking strength, elongation at break, and coefficient of variation of breaking strength: tested according to GB / T 16604-2017 Elongation at break of polyester industrial yarn under condition 2.

[0035] Boiling water shrinkage: tested according to the skein method in GB / T 6505-2017 Test methods for thermal shrinkage of chemical fiber filaments.

[0036] Example 1

[0037] A preparation method of a multi-component outdoor equipment recycled low-melting point filament, the specific steps are as follows:

[0038] (1) Preparation of raw materials:

[0039] Caprolactam;

[0040] Dibasic acid: adipic acid;

[0041] Dihydric alcohol: ethylene glycol;

[0042] Waste PET: Polyester filament foam (Zhejiang Xinfengming Chemical Fiber Co., Ltd., colorless pure white polyester);

[0043] Polyamide 6: Relative viscosity is 2.4;

[0044] (2) The preparation process of polyamide 6 esterified products is as follows:

[0045] First, caprolactam was hydrolyzed and ring-opened with a diacid to prepare polyamide 6 segments. Then, a diol was added to modify the polyamide 6 segments by end-group esterification to obtain polyamide 6 esterified products. The structural formula of polyamide 6 esterified products is as follows:

[0046] ;

[0047] The molar ratio of caprolactam to diacid was 4:1, and the amount of water was 2% of the mass of caprolactam; the molar ratio of diol to diacid was 2.1:1; the ring-opening temperature was 200℃, the pressure was 0.2MPa, and the time was 3h; the number average molecular weight of the polyamide 6 segment was 510g / mol; the esterification was performed under normal pressure, the esterification temperature was 230℃, and the esterification time was 2h.

[0048] like Figure 1 As shown, chemical shifts of 3.88 ppm, 3.06 ppm, 2.12 ppm, 2.06 ppm, and 1.80 ppm are characteristic hydrogen atom peaks from PA6 segments at positions 5, 1, 4, 2, and 3, respectively. Chemical shift 3.12 ppm is a characteristic hydrogen atom peak from the carbon atom at position 1' that is attached to the ester group after esterification of the PA6 prepolymer. Chemical shifts of 2.93 ppm and 2.19 ppm are characteristic hydrogen atom peaks from adipic acid at positions 6 and 7, respectively. Chemical shifts of 4.37 ppm, 4.45 ppm, 4.69 ppm, and 4.79 ppm are considered to be characteristic hydrogen atom peaks from ethylene glycol, proving the successful preparation of polyamide 6 esterified compounds.

[0049] (3) After mixing waste PET with polyamide 6 ester, the mixture is melted and depolymerized by a twin-screw extruder. The depolymerized melt is then transported to a reactor, and ethylene terephthalate is added to the reactor and homogenized before polycondensation reaction to obtain recycled low-melting-point polyester.

[0050] The amount of polyamide 6 esterified is 10% of the mass of waste PET, the depolymerization temperature is 250℃, the depolymerization time is 10min, and the degree of polymerization of the depolymerized product is 10; the amount of polyethylene terephthalate added is 15% of the total mass of the material in the reactor; the homogenization temperature is 240℃, the homogenization time is 20min; the polycondensation temperature is 260℃, and the vacuum degree during polycondensation is 100Pa.

[0051] The prepared regenerated low-melting polyester has an intrinsic viscosity of 0.85 dl / g and a melting point of 120℃.

[0052] (4) A multi-component regenerated low-melting filament for outdoor equipment is prepared by means of skin-core composite spinning, taking the regenerated low-melting polyester as the skin layer and polyamide 6 as the core layer.

[0053] The process parameters of the skin-core composite spinning are as follows: the melting temperature of the core layer is 280℃, the melting temperature of the skin layer is 200℃, the mass ratio of the skin to the core is 5:5, the cooling is carried out by means of ring blowing, the cooling air temperature is 23℃, the winding speed is 3300 m / min, and the draft ratio is 1.26.

[0054] The multi-component regenerated low-melting filament for outdoor equipment prepared finally has a linear density of 265 dtex, a breaking strength of 2 cN / dtex, an elongation at break of 105%, a boiling water shrinkage of 45%, and a breaking strength variation coefficient of 2%.

[0055] Comparative Example 1

[0056] A method for preparing a regenerated low-melting filament, which is basically the same as that of Example 1, except that the polyamide 6 ester has a degree of polymerization of 7, i.e., the molar ratio of caprolactam to dibasic acid in the preparation of the polyamide 6 ester is 7:1.

[0057] The prepared regenerated low-melting polyester has an intrinsic viscosity of 0.88 dl / g and a melting point of 160℃.

[0058] Comparing Comparative Example 1 with Example 1, it can be found that the low-melting polyester of Comparative Example 1 has a higher melting point and cannot be controlled within the range of 120-140℃, which makes the prepared fiber unable to match the subsequent hot air forming process, resulting in the inability to prepare a low-melting polyester that can be applied to the existing hot air forming production line. This is because when the degree of polymerization of the polyamide 6 segment exceeds 6, a fixed melting point greater than 170℃ will appear. In the polymerization process, chain growth is mainly through ester exchange reaction, and amide exchange between polyamide segments is difficult to occur, so the melting point of the polyamide segment is retained in the polymer, making the regenerated low-melting polyester unable to meet the melting point range of 120-140℃, difficult to match the existing hot air forming process, and unable to prepare the target product.

[0059] Example 2

[0060] A method for preparing a multi-component regenerated low-melting filament for outdoor equipment, the specific steps of which are as follows:

[0061] (1) Preparation of raw materials:

[0062] Caprolactam;

[0063] Dibasic acid: glutaric acid;

[0064] Diol: propylene glycol;

[0065] Waste PET: polyester fabric bubble material (Suzhou Jiulong Regeneration Technology Co., Ltd., colorless and pure white polyester);

[0066] Polyamide 66: relative viscosity of 2.8;

[0067] (2) The preparation process of the polyamide 6 ester is as follows:

[0068] First, caprolactam and diacid are hydrolyzed to prepare a polyamide 6 segment, and then diol is added to modify the end group of the polyamide 6 segment to obtain a polyamide 6 ester. The structural formula of the polyamide 6 ester is as follows:

[0069] ;

[0070] The molar ratio of caprolactam to diacid is 6:1, and the amount of water is 3% of the mass of caprolactam. The molar ratio of diol to diacid is 2.2:1. The ring-opening temperature is 205°C, the pressure is 0.25 MPa, and the time is 2.75 h. The number average molecular weight of the polyamide 6 segment is 750 g / mol. The esterification is carried out at normal pressure, and the esterification temperature is 232°C and the esterification time is 1.75 h.

[0071] (3) After mixing the waste PET and the polyamide 6 ester, the mixture is melted and depolymerized by a double screw, and then the melted product is transported to a reactor, and terephthalic acid ethylene glycol is added to the reactor and homogenized, and then a polycondensation reaction is carried out to obtain a regenerated low-melting-point polyester;

[0072] The amount of polyamide 6 ester is 8% of the mass of waste PET, the depolymerization temperature is 255°C, the depolymerization time is 9 min, and the degree of polymerization of the depolymerization product is 11. The amount of terephthalic acid ethylene glycol added is 14% of the total mass of the substances in the reactor. The homogenization temperature is 245°C, and the homogenization time is 18 min. The polycondensation temperature is 265°C, and the vacuum degree during polycondensation is 100 Pa.

[0073] The intrinsic viscosity of the prepared regenerated low-melting-point polyester is 0.8 dl / g, and the melting point is 128°C.

[0074] (4) A multi-component regenerated low-melting-point filament for outdoor equipment is prepared by skin-core composite spinning using the regenerated low-melting-point polyester as the skin layer and polyamide 66 as the core layer.

[0075] The process parameters of the skin-core composite spinning are as follows: the core layer melting temperature is 285°C, the skin layer melting temperature is 205°C, the skin-core composite mass ratio is 4:6, the cooling is carried out by ring blowing, the cooling air temperature is 18°C, the winding speed is 3000 m / min, and the draw ratio is 1.4.

[0076] The final prepared multi-component outdoor equipment recycled low-melting point filament has a linear density of 245 dtex, a breaking strength of 2.4 cN / dtex, an elongation at break of 106%, a boiling water shrinkage of 47%, and a breaking strength variation coefficient of 3%.

[0077] Example 3

[0078] A preparation method of a multi-component outdoor equipment recycled low-melting point filament, the specific steps are as follows:

[0079] (1) Preparation of raw materials:

[0080] Caprolactam;

[0081] Dibasic acid: heptanedioic acid;

[0082] Dihydric alcohol: butanediol;

[0083] Waste PET: polyester-containing cloth foam (Taikang County Kuoquan Renewable Resources Co., Ltd., non-ferrous pure polyester cloth foam);

[0084] Polyamide 6: relative viscosity of 2.6;

[0085] (2) The preparation process of polyamide 6 ester is as follows:

[0086] First, caprolactam and dibasic acid are hydrolyzed to prepare polyamide 6 segments, and then dihydric alcohol is added to modify the end groups of the polyamide 6 segments to obtain polyamide 6 ester. The structural formula of the polyamide 6 ester is as follows: ;

[0087] Among them, the molar ratio of caprolactam to dibasic acid is 5:1, the amount of water is 2% of the mass of caprolactam; the molar ratio of dihydric alcohol to dibasic acid is 2.1:1; the ring-opening temperature is 210°C, the pressure is 0.3 MPa, and the time is 2.5 h; the number average molecular weight of the polyamide 6 segment is 650 g / mol; esterification is carried out at normal pressure, and the esterification temperature is 235°C and the esterification time is 1.5 h.

[0088] (3) After mixing the waste PET and the polyamide 6 ester, melt depolymerization is carried out by a double screw, and then the depolymerized melt is transported to a reactor, terephthalic acid glycol ester is added to the reactor and homogenized, and then a polycondensation reaction is carried out to obtain a recycled low-melting point polyester;

[0089] Among them, the amount of polyamide 6 ester is 9% of the mass of waste PET, the depolymerization temperature is 260°C, the depolymerization time is 8 min, and the polymerization degree of the depolymerization product is 11; the amount of terephthalic acid glycol ester added is 13% of the total mass of substances in the reactor; the homogenization temperature is 250°C, and the homogenization time is 16 min; the polycondensation temperature is 270°C, and the vacuum degree during polycondensation is 150 Pa;

[0090] The prepared regenerated low-melting polyester has an intrinsic viscosity of 0.75 dl / g and a melting point of 132°C.

[0091] (4) A multi-component outdoor equipment regenerated low-melting filament is prepared by means of sheath-core composite spinning, taking the regenerated low-melting polyester as the sheath layer and polyamide 6 as the core layer.

[0092] The process parameters of the sheath-core composite spinning are as follows: the core layer melting temperature is 290°C, the sheath layer melting temperature is 210°C, the sheath-core composite mass ratio is 5:5, the cooling is carried out by means of ring blowing air cooling, the cooling air temperature is 20°C, the winding speed is 3100 m / min, and the draft ratio is 1.3.

[0093] The final prepared multi-component outdoor equipment regenerated low-melting filament has a linear density of 260 dtex, a breaking strength of 2.6 cN / dtex, an elongation at break of 107%, a boiling water shrinkage of 48%, and a breaking strength variation coefficient of 3.5%.

[0094] Example 4

[0095] A preparation method of a multi-component outdoor equipment regenerated low-melting filament is provided, and the specific steps are as follows:

[0096] (1) Preparation of raw materials:

[0097] Caprolactam;

[0098] Dibasic acid: octanedioic acid;

[0099] Dialcohol: pentanediol;

[0100] Waste PET: polyester waste yarn (Zhejiang Hengyi Petrochemical Sales Co., Ltd., polyester filament waste yarn);

[0101] Polyamide 6: relative viscosity is 2.8;

[0102] (2) The preparation process of the polyamide 6 ester is as follows:

[0103] First, caprolactam and dibasic acid are subjected to hydrolysis ring-opening to prepare a polyamide 6 segment, and then dialcohol is added to modify the end group of the polyamide 6 segment to obtain a polyamide 6 ester. The structural formula of the polyamide 6 ester is as follows:

[0104] ;

[0105] Among them, the molar ratio of caprolactam to dibasic acid is 6:1, the amount of water is 3% of the mass of caprolactam; the molar ratio of dialcohol to dibasic acid is 2.2:1; the ring-opening temperature is 215°C, the pressure is 0.35 MPa, and the time is 2.25 h; the number average molecular weight of the polyamide 6 segment is 780 g / mol; the esterification is carried out under normal pressure, the esterification temperature is 236°C, and the esterification time is 1.5 h.

[0106] (3) the waste PET and polyamide 6 ester are mixed, then the mixture is melted and depolymerized by a double screw, then the depolymerized melt is transported to a reactor, terephthalic acid glycol ester is added into the reactor and homogenized, and then a polycondensation reaction is carried out to obtain a regenerated low-melting-point polyester;

[0107] The amount of polyamide 6 ester is 6% of the mass of waste PET, the depolymerization temperature is 265℃, the depolymerization time is 7min, and the polymerization degree of the depolymerization product is 13; the amount of terephthalic acid glycol ester added is 12% of the total mass of substances in the reactor; the homogenization temperature is 255℃, the homogenization time is 14min; the polycondensation temperature is 275℃, and the vacuum degree during polycondensation is 100Pa;

[0108] The intrinsic viscosity of the prepared regenerated low-melting-point polyester is 0.75dl / g, and the melting point is 136℃.

[0109] (4) a multi-component outdoor equipment regenerated low-melting-point filament is prepared by skin-core composite spinning with the prepared regenerated low-melting-point polyester as the skin layer and polyamide 6 as the core layer;

[0110] The process parameters of the skin-core composite spinning are as follows: the core layer melting temperature is 295℃, the skin layer melting temperature is 215℃, the skin-core composite mass ratio is 4:6, the cooling is carried out by ring blowing air cooling, the cooling air temperature is 25℃, the winding speed is 3200m / min, and the draw ratio is 1.4.

[0111] The linear density of the finally prepared multi-component outdoor equipment regenerated low-melting-point filament is 240dtex, the breaking strength is 2.8cN / dtex, the breaking elongation is 103%, the boiling water shrinkage is 42%, and the breaking strength variation coefficient is 3%.

[0112] Example 5

[0113] A preparation method of a multi-component outdoor equipment regenerated low-melting-point filament is provided, and the specific steps are as follows:

[0114] (1) preparation of raw materials:

[0115] Caprolactam;

[0116] Dibasic acid: azelaic acid;

[0117] Dibasic alcohol: ethylene glycol;

[0118] Waste PET: polyester waste cloth (Hubei Weishuanyuan Energy-saving and Environment-friendly Technology Co., Ltd., non-ferrous polyester waste cloth);

[0119] Polyamide 66: the relative viscosity is 2.6;

[0120] (2) the preparation process of polyamide 6 ester is as follows:

[0121] First, caprolactam and diacid are hydrolyzed to prepare a polyamide 6 segment, and then a dihydric alcohol is added to modify the end group of the polyamide 6 segment to obtain a polyamide 6 esterification product; the structural formula of the polyamide 6 esterification product is as follows: ;

[0122] The molar ratio of caprolactam to diacid is 5:1, and the amount of water is 2% of the mass of caprolactam; the molar ratio of dihydric alcohol to diacid is 2.1:1; the ring-opening temperature is 220°C, the pressure is 0.4 MPa, and the time is 2 h; the number average molecular weight of the polyamide 6 segment is 620 g / mol; the esterification is atmospheric pressure esterification, the esterification temperature is 238°C, and the esterification time is 1.25 h.

[0123] (3) After mixing the waste PET and the polyamide 6 esterification product, melt depolymerization is carried out by a double screw, and then the melt after depolymerization is transported to a reactor, terephthalic acid glycol is added to the reactor and homogenized, and then a polycondensation reaction is carried out to obtain a regenerated low-melting-point polyester;

[0124] The amount of polyamide 6 esterification product is 7% of the mass of waste PET, the depolymerization temperature is 268°C, the depolymerization time is 6 min, and the polymerization degree of the depolymerization product is 13; the amount of terephthalic acid glycol added is 11% of the total mass of substances in the reactor; the homogenization temperature is 258°C, and the homogenization time is 12 min; the polycondensation temperature is 278°C, and the vacuum degree during polycondensation is 150 Pa;

[0125] The intrinsic viscosity of the regenerated low-melting-point polyester prepared is 0.8 dl / g, and the melting point is 133°C.

[0126] (4) A multi-component outdoor equipment regenerated low-melting-point filament is prepared by skin-core composite spinning with the regenerated low-melting-point polyester as the skin layer and polyamide 66 as the core layer;

[0127] The process parameters of the skin-core composite spinning are as follows: the core layer melting temperature is 298°C, the skin layer melting temperature is 218°C, the skin-core composite mass ratio is 5:5, the cooling is carried out by ring blowing air cooling, the cooling air temperature is 22°C, the winding speed is 3400 m / min, and the draw ratio is 1.2.

[0128] The linear density of the finally prepared multi-component outdoor equipment regenerated low-melting-point filament is 270 dtex, the breaking strength is 2.6 cN / dtex, the breaking elongation is 105%, the boiling water shrinkage is 44%, and the breaking strength variation coefficient is 3.5%.

[0129] Example 6

[0130] A preparation method of a multi-component outdoor equipment regenerated low-melting-point filament is as follows:

[0131] (1) Preparation of raw materials:

[0132] Caprolactam;

[0133] Dibasic acid: sebacic acid;

[0134] Dihydric alcohol: pentanediol;

[0135] Waste PET: polyester-containing waste textiles (Suzhou Jiulong Regeneration Technology Co., Ltd., polyester waste textiles);

[0136] Polyamide 66: relative viscosity of 2.4;

[0137] (2) The preparation process of the polyamide 6 ester is as follows:

[0138] First, caprolactam and dibasic acid are subjected to hydrolysis ring opening to prepare a polyamide 6 segment, and then dihydric alcohol is added to modify the end group of the polyamide 6 segment to obtain a polyamide 6 ester. The structural formula of the polyamide 6 ester is as follows: ;

[0139] The molar ratio of caprolactam to dibasic acid is 4:1, and the amount of water is 3% of the mass of caprolactam. The molar ratio of dihydric alcohol to dibasic acid is 2.2:1. The ring opening temperature is 210°C, the pressure is 0.3 MPa, and the time is 2.5 h. The number average molecular weight of the polyamide 6 segment is 550 g / mol. The esterification is carried out at normal pressure, and the esterification temperature is 240°C and the esterification time is 1 h.

[0140] (3) After mixing the waste PET and the polyamide 6 ester, the mixture is subjected to melt depolymerization by a double screw, and then the depolymerized melt is transported to a reactor, and terephthalic acid glycol ester is added to the reactor and homogenized, and then subjected to polycondensation reaction to obtain a regenerated low-melting-point polyester;

[0141] The amount of the polyamide 6 ester is 5% of the mass of the waste PET, the depolymerization temperature is 270°C, the depolymerization time is 5 min, and the polymerization degree of the depolymerization product is 15. The amount of terephthalic acid glycol ester added is 10% of the total mass of the substances in the reactor. The homogenization temperature is 260°C, and the homogenization time is 10 min. The polycondensation temperature is 280°C, and the vacuum degree during polycondensation is 100 Pa.

[0142] The intrinsic viscosity of the prepared regenerated low-melting-point polyester is 0.85 dl / g, and the melting point is 140°C.

[0143] (4) A multi-component regenerated low-melting-point filament for outdoor equipment is prepared by skin-core composite spinning, taking the regenerated low-melting-point polyester as the skin layer and polyamide 66 as the core layer.

[0144] The process parameters of the core-sheath composite spinning are as follows: the core layer melting temperature is 300 DEG C, the sheath layer melting temperature is 220 DEG C, the mass ratio of the core-sheath composite is 4:6, the cooling is carried out by ring blowing, the cooling air temperature is 20 DEG C, the winding speed is 3500 m / min, and the draft ratio is 1.1.

[0145] The final prepared multi-component recycled low-melting-point filament for outdoor equipment has a linear density of 275 dtex, a breaking strength of 3 cN / dtex, an elongation at break of 106%, a boiling water shrinkage of 47%, and a breaking strength variation coefficient of 3%.

Claims

1. A method for preparing recycled low-melting-point filaments for multi-component outdoor equipment, characterized in that: First, waste PET is mixed with polyamide 6 ester and then melted and depolymerized by a twin-screw extruder. The depolymerized melt is then transported to a reactor, where ethylene terephthalate is added and homogenized before polycondensation to obtain recycled low-melting-point polyester. Finally, using the recycled low-melting-point polyester as the sheath and polyamide 6 or polyamide 66 as the core, multi-component recycled low-melting-point filaments for outdoor equipment are produced by sheath-core composite spinning. The molecular structure of polyamide 6 esterified is one of the following structures: ； ； ； ； ； 。 2. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, The preparation process of polyamide 6 esterified products is as follows: first, caprolactam and dicarboxylic acid are hydrolyzed and ring-opened to prepare polyamide 6 segments with a degree of polymerization ≤6, and then the polyamide 6 segments are modified by adding diol to end-group esterification to obtain polyamide 6 esterified products. The dicarboxylic acid is glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, or sebacic acid, and the diol is ethylene glycol, propylene glycol, butanediol, or pentanediol.

3. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 2, characterized in that, The molar ratio of caprolactam to dicarboxylic acid is 4~6:1, and the amount of water used is 2~3% of the mass of caprolactam; the ring-opening temperature is 200~220℃, the pressure is 0.2~0.4MPa, and the time is 2~3h; the number average molecular weight of polyamide 6 segments is 500~800g / mol.

4. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 2, characterized in that, Esterification was performed under normal pressure at a temperature of 230-240℃ for 1-2 hours; the molar ratio of diol to diacid was 2.1-2.2:

1.

5. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, Waste PET is polyester waste yarn, polyester waste cloth or waste textile containing polyester; the amount of polyamide 6 esterified is 5~10% of the mass of waste PET, the depolymerization temperature is 250~270℃, the depolymerization time is 5~10min, and the degree of polymerization of the depolymerization product is 10~15.

6. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, The amount of ethylene terephthalate added is 10-15% of the total mass of the material in the reactor; the homogenization temperature is 240-260℃, the homogenization time is 10-20 min; the polycondensation temperature is 260-280℃, and the vacuum degree during polycondensation is <200 Pa.

7. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, The intrinsic viscosity of recycled low-melting-point polyester is 0.75~0.85 dl / g, and the melting point is 120~140℃.

8. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, The relative viscosity of polyamide 6 or polyamide 66 is 2.4~2.8; the process parameters for core-sheath composite spinning are: core melting temperature 280~300℃, sheath melting temperature 200~220℃, core-sheath composite ratio 5:5 or 4:6, cooling is achieved by ring blowing, cooling air temperature is 18~25℃, winding speed is 3000~3500m / min, and draw ratio is 1.1~1.

4.

9. The method for preparing a multi-component recycled low-melting-point filament for outdoor equipment according to claim 1, characterized in that, The linear density of the recycled low-melting-point filament for multi-component outdoor equipment is 240~280 dtex, the breaking strength is 2.0~3.0 cN / dtex, the breaking elongation is 105±2.0%, the boiling water shrinkage is 45±3%, and the coefficient of variation of breaking strength is ≤3.5%.

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