Antibacterial regenerated polyamide 6 as well as preparation method and application thereof

Abstract

The invention relates to antibacterial regenerated polyamide 6 as well as a preparation method and application thereof, and belongs to the technical field of waste polyamide 6 recovery, the preparation method comprises the following steps: carrying out condensation polymerization on a first polyamide 6 middle polymer and an antibacterial functional polyamide 6 middle polymer to obtain the antibacterial regenerated polyamide 6, wherein the antibacterial functional polyamide 6 middle polymer is formed by reaction of a second polyamide 6 middle polymer, an antibacterial monomer and an end group modifier; in the prepared antibacterial regenerated polyamide 6, the content of a hot water extractable substance is 2.0 to 3.0 weight percent, and the content of a cyclic dimer is 0.1 to 0.5 weight percent; according to the application, the antibacterial regenerated polyamide 6 is prepared into the antibacterial regenerated polyamide 6 fiber; the method is simple, the content of hot water extractable matter in the prepared antibacterial regenerated polyamide 6 is low, and the antibacterial functional structure in the prepared fiber is stable. The antibacterial effect is lasting.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste polyamide 6 and relates to an antibacterial regenerated polyamide 6 and a preparation method and application thereof. Background Art

[0002] Polyamide 6 fiber boasts high breaking strength, excellent abrasion resistance, good moisture absorption, good dyeability, excellent elastic recovery, and superior fatigue resistance, making it widely used in textiles, apparel, tire cord, and filter materials. While the stable chemical properties of polyamide 6 contribute to its promising applications, they also make it difficult to degrade after disposal. Currently, waste polyamide 6 is primarily disposed of by landfill or incineration, placing a significant burden on both economic and ecological resources.

[0003] In daily life and professional fields such as medicine and sports, the antibacterial function of polyamide 6 fiber products is a core requirement to ensure safe and healthy use. However, the existing antibacterial modification of native polyamide 6 fibers mostly relies on mechanical blending or surface coating processes (such as patent application CN119800718A and patent application CN119877139A). The former is prone to reduce fiber strength due to poor compatibility between inorganic antibacterial agents and the matrix, while the latter is insufficiently durable due to weak adhesion of the antibacterial agents. Both methods have problems such as complex processes, high costs or environmental pollution. Therefore, the key direction to break through the existing technical bottleneck is to uniformly embed antibacterial groups into the polyamide 6 molecular chain through in-situ modification technology to achieve a synergistic improvement in antibacterial function and material performance.

[0004] Polyamide 6 hot water extractables mainly refer to linear or cyclic oligomers and monomers with a degree of polymerization less than 10. They are named after the fact that these oligomers and monomers can be dissolved in hot water by extracting polyamide 6 at 97°C or higher. Traditionally, polyamide 6 prepared from caprolactam will leave 8-10 wt% of hot water extractables. The generation of such extracts is mainly due to two reasons: Figure 1 As shown in Figure 2, on the one hand, the monomer caprolactam of polyamide 6 has a ring-opening reaction equilibrium during the polymerization process, so that a part of the caprolactam fails to participate in the ring-opening reaction and remains in the form of monomers. At the same time, the low molecular weight linear molecules formed after the ring opening cannot fully participate in the polymerization reaction due to the limitation of reaction kinetics, and eventually become hot water extractables. On the other hand, as shown in Figure 2, Figure 2 As shown in the figure, the addition polymerization reaction of polyamide 6 is reversible. The terminal amino group of its molecular chain will attack the amide bond in the molecular chain (terminal group bites back), resulting in chain breakage and the formation of cyclic oligomers. These cyclic oligomers will also become hot water extractables.

[0005] Reducing the hot water extractable content of polyamide 6 can significantly improve fiber processing performance, product quality stability, and industrial production efficiency, while also reducing resource waste and equipment wear. While extending the hot water extraction time can reduce the content, it increases energy consumption by over 30% and does not fundamentally address the oligomer formation problem. Therefore, optimizing the polymerization process to inhibit oligomer formation is a key strategy for improving fiber quality and reducing industrial energy consumption.

[0006] In summary, in order to meet the sustainable development needs of polyamide 6 materials throughout their entire life cycle, it is urgent to build a three-in-one technical innovation system of "efficient recycling of waste polyamide 6 - in-situ antibacterial functionalization - source control of hot water extractables". Summary of the Invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide an antibacterial regenerated polyamide 6 and a preparation method and application thereof.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing antibacterial regenerated polyamide 6, comprising subjecting a first polyamide 6 mesomer to a condensation reaction with an antibacterial functional polyamide 6 mesomer to obtain the antibacterial regenerated polyamide 6;

[0010] The antibacterial functional polyamide 6 midipolymer is formed by reacting a second polyamide 6 midipolymer, an antibacterial monomer, and an end group modifier; the antibacterial monomer contains an amino group; the end group modifier contains a carboxyl group; the end carboxyl group of the second polyamide 6 midipolymer undergoes an amidation reaction with the amino group of the antibacterial monomer, and the end amino group of the second polyamide 6 midipolymer undergoes an amidation reaction with the carboxyl group of the end group modifier;

[0011] The antimicrobial monomer is guanidine salt or chitosan;

[0012] The terminal group modification agent is asparagine, glutamic acid, lysine, glutamine or trimesic acid;

[0013] The number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer is 3000-6000 g / mol.

[0014] The present invention can produce antibacterial recycled polyamide 6 with low hot water extractables, mainly due to the following reasons:

[0015] ① In the present invention, the terminal amino group of the second polyamide 6 polymer undergoes an amidation reaction with the carboxyl group of the terminal modifier, and its reaction activity is greatly reduced. Although the terminal modifier and the antibacterial monomer still have terminal amino groups, they are limited by the structure of the terminal modifier and the antibacterial monomer themselves and it is difficult to form a stable seven-membered ring or multiple seven-membered ring structure like caprolactam or a cyclic dimer. Therefore, even if these terminal amino groups attack the amide bond in the molecular chain where they are located, it is difficult to form a stable cyclic oligomer.

[0016] ② If Figure 3 As shown in the figure, although the main chain of antibacterial recycled polyamide 6 contains terminal amino groups, these terminal amino groups need a larger activity space to attack the amide bonds in their molecular chains (terminal group backbiting). Antibacterial recycled polyamide 6 has a comb-shaped structure, and the branched structure of the molecular chains of adjacent antibacterial recycled polyamide 6 will reduce the activity space of the terminal amino groups, increasing the difficulty of the terminal amino groups attacking the amide bonds in their molecular chains.

[0017] ③ The present invention prepares antibacterial regenerated polyamide 6 through mesopolymer polymerization, which does not require the caprolactam ring-opening process of the traditional polyamide 6 synthesis process, so there is no caprolactam residue caused by ring-opening equilibrium.

[0018] ④ The present invention prepares antibacterial regenerated polyamide 6 by polymerizing the intermediate polymer. Since the intermediate polymer has a certain molecular weight, only a shorter condensation reaction time is required to obtain the target product. The shorter the condensation reaction time, the lower the probability that the terminal amino group of the molecular chain will attack the amide bond in the molecular chain where it is located.

[0019] As the preferred technical solution:

[0020] In the preparation method of the antibacterial regenerated polyamide 6 described above, the guanidine salt is one or more of polyaminopropyl biguanide, aminoguanidine bicarbonate, aminoguanidine carbonate, aminoguanidine sulfate, agmatine sulfate, 1-aminoformylguanidine, sulfaguanidine, 1-o-tolylbiguanide, N-(2-methoxyethyl)guanidine, isoquinoline sulfate and guanidine hydrochloride.

[0021] The method for preparing an antibacterial regenerated polyamide 6 comprises the following steps of: diverting a second polyamide 6 polymer to a modification kettle through a two-way distributing valve; adding an aqueous solution of an antibacterial monomer; reacting the mixture at 160-170° C. and 0.62-0.79 MPa for 60-120 min; and then adding an aqueous solution of an end group modifier; reacting the mixture at 160-170° C. and 0.62-0.79 MPa for 60-120 min to obtain the antibacterial functional polyamide 6 polymer, wherein the mass fraction of the aqueous solution of the antibacterial monomer is 10%-50%, the mass fraction of the aqueous solution of the end group modifier is 5%-10%, and the number average molecular weight of the antibacterial functional polyamide 6 polymer is 2000-4000 g / mol.

[0022] like Figure 4As shown, during the preparation process of the antibacterial functional polyamide 6 mesomer, after adding an aqueous solution of the antibacterial monomer, at 160-170°C, the ability of water molecules to attack the amide bond is very weak, but the terminal amino group of the antibacterial monomer and the terminal carboxyl group of the second polyamide 6 mesomer maintain a high reactivity. At the same time, at this temperature, the reaction system still maintains a homogeneous state, and the terminal amino group of the antibacterial monomer and the terminal carboxyl group of the second polyamide 6 mesomer can achieve uniform and rapid amidation reaction to obtain the waste polyamide 6 mesomer modified with the antibacterial monomer; after adding an aqueous solution of the end group modifier, the terminal amino group of the waste polyamide 6 mesomer modified with the antibacterial monomer undergoes an amidation reaction with the terminal carboxyl group of the end group modifier having a trifunctional group, to obtain an antibacterial functional polyamide 6 mesomer having a difunctional group;

[0023] The preparation method of the antibacterial regenerated polyamide 6 as described above is as follows: the polycondensation reaction is carried out in a polymerization kettle; the polycondensation reaction temperature is 230-250°C; the time is 2-4h; nitrogen or inert gas purging is carried out during the polycondensation reaction; or the polycondensation reaction is carried out in a vacuum environment with a vacuum degree of 50-300Pa; during the polycondensation reaction, the present invention accelerates the removal of hot water extractables by nitrogen or inert gas purging or vacuum extraction; the hot water extractables represented by caprolactam have a small molecular weight and are easily vaporized or separated from the melt by external force; the purpose of nitrogen or inert gas purging or vacuum extraction is to provide such external force. The reaction equation of the polycondensation reaction of the first polyamide 6 mesomer and the antibacterial functional polyamide 6 mesomer is as follows: Figure 5 shown.

[0024] As described above, in a method for preparing an antibacterial regenerated polyamide 6, before the first polyamide 6 mesomer and the antibacterial functional polyamide 6 mesomer are put into a balancing kettle at a temperature of 210-240°C (the balancing kettle itself is at normal pressure, that is, the absolute pressure is 101 kPa. Only after the materials are added will the balancing kettle generate water vapor pressure) until the pressure reaches 1.9-3.3 MPa. The pressure is then released to 0.1 MPa at a pressure release rate of 10-30 kPa / h. The purpose of the pressure release is to remove water, and the water vapor generated during the pressure release is condensed into a condensation water tank.

[0025] The preparation method of the antibacterial recycled polyamide 6 as described above, the preparation process of the first polyamide 6 intermediate polymer and the second polyamide 6 intermediate polymer is as follows: waste polyamide 6 products (pure polyamide 6 waste silk, waste blocks, waste cloth or blended fabrics with a polyamide 6 content of more than 90%) with water at a bath ratio of 1:1-7 are hydrolyzed in a hydrolysis kettle at 180-240°C for 20-120 minutes to obtain waste polyamide 6 intermediate polymer, and the waste polyamide 6 intermediate polymer is divided into two parts to obtain the first Polyamide 6 intermediate polymer and second polyamide 6 intermediate polymer; the second polyamide 6 intermediate polymer is entirely used to prepare antibacterial functional polyamide 6 intermediate polymer, and the first polyamide 6 intermediate polymer and the antibacterial functional polyamide 6 intermediate polymer are entirely used to prepare antibacterial recycled polyamide 6; the mass of the antibacterial monomer is 10-50wt% of the mass of the waste polyamide 6 product, and the mass of the end group modifier is 5-10wt% of the mass of the waste polyamide 6 product; the reaction equation for preparing the waste polyamide 6 intermediate polymer is as follows: Figure 6 As shown;

[0026] The present invention sets the temperature of the hydrolysis reaction to 180-240° C. because: during the hydrolysis process of the waste polyamide 6 product, although water molecules enter the interior of the polyamide 6 before 160° C., the energy of the water molecules at this time is insufficient to destroy the crystal structure and molecular structure of the polyamide 6, and the polyamide 6 still maintains a solid state; when the temperature rises to above 160° C., the hydrogen bonds between the polyamide 6 molecular chains are destroyed by the water molecules, the crystal structure thereof is destroyed, and the polyamide 6 and water become a homogeneous state; then, as the temperature rises, the ability of the water molecules to attack the amide bonds is enhanced, and the amide bonds are hydrolyzed into amino groups and carboxyl groups, thereby achieving the breakage of the polyamide 6 molecular chains, which is macroscopically manifested as a decrease in the viscosity of the polyamide 6; setting the temperature of the hydrolysis reaction to 180-240° C. can utilize the strong nucleophilicity of the water molecules to achieve the rapid degradation of the waste polyamide 6 molecular chains, thereby generating waste polyamide 6 mesomers containing a large number of terminal carboxyl groups.

[0027] In the above-mentioned method for preparing an antibacterial recycled polyamide 6, the mass of the polymer in the second polyamide 6 is 5-20% of the mass of the waste polyamide 6 product, and the obtained antibacterial recycled polyamide 6 is recorded as the first antibacterial recycled polyamide 6.

[0028] In the above-mentioned method for preparing an antibacterial recycled polyamide 6, the mass of the polymer in the second polyamide 6 is 21-50% of the mass of the waste polyamide 6 product, and the obtained antibacterial recycled polyamide 6 is recorded as the second antibacterial recycled polyamide 6.

[0029] The present invention also provides a first antibacterial recycled polyamide 6, which is prepared by the preparation method of the antibacterial recycled polyamide 6 described above; the first antibacterial recycled polyamide 6 has a number average molecular weight of 14,000-30,000 g / mol, a relative viscosity of 2.0-3.6, a melting point of 218.0-222.0°C, a PDI of 1.5-2.5, a hot water extractable content of 2.0-3.0 wt%, and a cyclic dimer content of 0.1-0.5 wt%.

[0030] The present invention also provides a second antibacterial recycled polyamide 6, which is prepared by the preparation method of the antibacterial recycled polyamide 6 described above; the second antibacterial recycled polyamide 6 has a number average molecular weight of 14,000-30,000 g / mol, a relative viscosity of 2.0-3.6, a melting point of 218.0-222.0°C, a PDI of 1.5-2.5, a hot water extractable content of 2.0-3.0 wt%, and a cyclic dimer content of 0.1-0.5 wt%.

[0031] The present invention also provides a method for preparing antibacterial regenerated polyamide 6 fiber, wherein the first antibacterial regenerated polyamide 6 described above is directly melt-spun, or the second antibacterial regenerated polyamide 6 described above is mixed with polyamide 6 in a mass ratio of 1:2-4 and then melt-spun to obtain the antibacterial regenerated polyamide 6 fiber;

[0032] Melt spinning uses FDY, UDY, POY, HOY or BCF processes;

[0033] The FDY process parameters include: spinning temperature 240-280°C, first godet speed 4000-4500 m / min, second godet speed 5000-6000 m / min, stretching ratio 1.1-1.5 times, cooling air temperature 15-25°C, cooling air speed 0.5-1 m / s, cooling air relative humidity 60%-90%;

[0034] The parameters of the UDY process include: spinning temperature 240-280°C, spinning speed 700-1500m / min, cooling air temperature 20-30°C, cooling air speed 0.3-1m / s, cooling air relative humidity 60%-80%;

[0035] The parameters of the POY process include: spinning temperature 240-280°C, spinning speed 4000-4500m / min, cooling air temperature 15-25°C, cooling air speed 0.3-0.6m / s, cooling air relative humidity 60%-80%;

[0036] The parameters of the HOY process include: spinning temperature 240-280°C, spinning speed 4500-6000m / min, cooling air temperature 15-20°C, cooling air speed 0.3-0.5m / s, cooling air relative humidity 80%-90%;

[0037] The BCF process parameters include: spinning temperature 240-280°C, cooling air temperature 20-30°C, cooling air speed 0.3-1m / s, cooling air relative humidity 60%-80%, feed roller temperature 60-120°C, stretching roller temperature 100-190°C, feed speed 300-1000m / min, stretching speed 1000-3500m / min, stretching ratio 3.5-5 times, deformation hot air temperature 190-230°C, air injection pressure 196-490kPa, winding speed 600-3000m / min, cooling air temperature 25°C;

[0038] The monofilament fineness of the antibacterial regenerated polyamide 6 fiber is 0.2-18 dtex, the breaking strength of the multifilament is 3.0-5.0 cN / dtex, and the multifilament consists of 36 or 72 monofilaments;

[0039] The antibacterial rates of antibacterial recycled polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans were 90.0-99.9%, 90.0-99.9% and 90.0-99.2%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans were 88.0-99.9%, 88.0-99.9% and 85.0-99.2%, respectively.

[0040] Beneficial effects:

[0041] (1) The present invention imparts functionality to waste polyamide 6 polymers through chemical modification, thereby increasing the added value of recycled waste polyamide 6 products. Furthermore, no additional dispersants or other additives and post-finishing processes are required, which is beneficial for reducing the carbon footprint of functional fabrics.

[0042] (2) In the present invention, the reaction temperature of the antimicrobial monomer and the waste polyamide 6 mesomer (i.e., the second polyamide 6 mesomer) is relatively low, which can reduce the loss of the antimicrobial monomer during the preparation process. Specifically, in the prior art, the polymerization temperature of polyamide 6 is 220-250°C, and the antimicrobial monomer is very easy to decompose or deteriorate at this temperature. In the present invention, the antimicrobial monomer is combined with the polyamide 6 molecular chain at 160-170°C. At this reaction temperature, the antimicrobial monomer is not easily lost due to decomposition or deterioration. After it is chemically bonded to the polyamide 6 molecular chain, its overall thermal stability is increased, and its functional properties will not be lost during the subsequent melt polymerization process.

[0043] (3) In the present invention, the antibacterial monomer is connected to the polyamide 6 molecular chain through a chemical bond, which improves its anti-precipitation property, heat resistance and long-term antibacterial effect, and ensures the stability of the antibacterial functional structure during thermal processing and use;

[0044] (4) In the present invention, the antibacterial monomer is firstly chemically bonded with the waste polyamide 6 mesomer (i.e., the second polyamide 6 mesomer) in a uniform water system, and then the functional component is linked to the molecular main chain by in situ polymerization. The homogeneity of the functional component and the molecular main chain enables the functional monomer to be uniformly dispersed;

[0045] (5) The present invention utilizes the reaction characteristics of amide bonds at different water temperatures to achieve different depolymerization and end-capping reactions in the same system. Specifically, by utilizing the nucleophilic attack of water molecules on the amide bonds at high temperatures, the amide bonds are broken into amino groups and carboxyl groups, and the waste polyamide 6 molecular chains are depolymerized into the required molecular chain length. Then, at a lower temperature, the nucleophilic attack activity of water molecules is reduced, and the terminal carboxyl groups and terminal amino groups can react to form amide bonds, thereby achieving the imparting of antibacterial functional monomers and the modification of end groups.

[0046] (6) The antibacterial regenerated polyamide 6 of the present invention has a low hot water extractable content, which can reduce the time spent in the subsequent extraction process;

[0047] (7) The present invention can control the content of the polymer in the second polyamide 6, so that functional masterbatch or functional fiber can be prepared according to its content during the application process (as a raw material for functional fiber, that is, direct melt spinning, as a functional masterbatch, that is, melt spinning after blending with polyamide 6). BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A process for preparing polyamide 6 from caprolactam;

[0049] Figure 2 Schematic diagram of the terminal amino group of the molecular chain attacking the amide bond in the molecular chain to produce caprolactam and cyclic dimer;

[0050] Figure 3 Schematic diagram of the "comb-shaped structure" polyamide 6 molecular chain arrangement that hinders the terminal amino group of the molecular chain from attacking the amide bond in the molecular chain;

[0051] Figure 4 The reaction equation for preparing antibacterial functional polyamide 6 mesomer;

[0052] Figure 5 is a reaction equation for the polycondensation reaction of the first polyamide 6 mesomer and the antimicrobial functional polyamide 6 mesomer;

[0053] Figure 6The reaction equation for preparing the polymer from waste polyamide 6 is:

[0054] Figure 7 A production device for the preparation and application of an antibacterial regenerated polyamide 6 of the present invention;

[0055] Among them, 1-hydrolysis kettle, 2-modification kettle, 3-balancing kettle I, 4-balancing kettle II, 5-polymerization kettle, 6-granulator, 7-extraction kettle, 8-dryer, 9-storage silo, 10-spinning equipment, 11-condensate tank, 12-two-way distribution valve, 13-metering valve, 14-pipeline I, 15-pipeline II, 16-pipeline III, 17-pipeline IV, 18-pipeline V, 19-pipeline VI, 20-pipeline VII, 21-pipeline VIII, 22-pipeline IX, 23-pipeline X. DETAILED DESCRIPTION

[0056] Below in conjunction with specific embodiment, further elaborate the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the present invention.

[0057] The testing methods for the relevant performance indicators of the embodiments and comparative examples are as follows:

[0058] Number average molecular weight and PDI (molecular weight distribution index): The number average molecular weight and PDI of the samples were measured using a GPC-50 gel permeation chromatograph (PL, UK). The instrument was equipped with a differential refractive index detector and a PL gel column (5µm mixed-C). 1,1,1,3,3,3-hexafluoro-2-propanol was used as the eluent at a flow rate of 1 mL / min. During the test, the sample was dried and dissolved in hexafluoroisopropanol to a concentration of 1.0 mg / mL. The test was performed when the column temperature reached 40±1°C.

[0059] Relative viscosity: Refer to GB / T 38138-2019 "Test method for fiber-grade polycaprolactam (PA6) slices" 5.2 Relative viscosity.

[0060] Melting point test: Refer to GB / T 38138-2019 "Fiber-grade polycaprolactam (PA6) slice test method" 5.7 melting point.

[0061] Hot water extractable content: Refer to 5.3 Hot water extractable content of GB / T 38138-2019 "Test method for fiber-grade polycaprolactam (PA6) slices".

[0062] Cyclic dimer content: The liquid obtained after the hot water extractable content test was used as a sample for qualitative and quantitative analysis of the cyclic dimer in the sample using a Shimadzu LC-16 high-performance liquid chromatograph (HPLC) equipped with a WondaSil C18-WR (200 mm, 5 μm particle size) column and a UV detector. The detection wavelength was 210 nm and the detection temperature was 40°C. A binary gradient method was used, with methanol and water as the mobile phases. The test method is as follows: Testing phase Time (min) Methanol ratio (Vol%) 1 2 10 2 17 70 3 18 70 4 18.1 10 5 20 10

[0063] Multifilament breaking strength: refer to GB / T 14344-2008 "Test method for tensile properties of chemical fiber filaments".

[0064] The antibacterial rate of antibacterial recycled polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans: refer to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles Part 3: Oscillation test method". The parameter ranges involved in the standard are set according to the maximum value.

[0065] Washing: Refer to GB / T 20944.3-2008 "Evaluation of antimicrobial properties of textiles Part 3: Oscillation test method" 10.1.2 Household twin-tub washing machine washing method, repeat 50 times.

[0066] Example 1

[0067] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0068] (1) Preparation of raw materials;

[0069] Waste polyamide 6 products;

[0070] The antibacterial monomer is chitosan (CAS No.: 9012-76-4, specification: deacetylation degree ≥ 95%, viscosity 50-100mPa.s);

[0071] The terminal group modifier is asparagine (CAS No.: 70-47-3, specification model: purity ≥98%);

[0072] water;

[0073] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:1 in a hydrolysis kettle at 180°C for 120 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, obtaining a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 5% of the mass of the waste polyamide 6 product;

[0074] The number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer obtained is 6000 g / mol;

[0075] (3) The second polyamide 6 midpolymer is diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 10% is added, and the mixture is reacted at 160°C and 0.79 MPa for 60 min. An aqueous solution of an end group modifier with a mass fraction of 5% is then added, and the mixture is reacted at 160°C and 0.62 MPa for 120 min to obtain an antibacterial functional polyamide 6 midpolymer; wherein the mass of the antibacterial monomer is 10 wt% of the mass of the waste polyamide 6 product; and the mass of the end group modifier is 5 wt% of the mass of the waste polyamide 6 product.

[0076] The number average molecular weight of the prepared antibacterial functional polyamide 6 mesomer is 4000 g / mol;

[0077] In the modification kettle, although the water temperature is low and the hydrolysis reaction is slow, it will still occur. At the same time, the carboxyl and amino groups in the added end group modifier will also partially participate in attacking the amide bond. Therefore, the number average molecular weight of the antibacterial functional polyamide 6 mesopolymer will be lower than the number average molecular weight of the second polyamide 6 mesopolymer.

[0078] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 210°C until the pressure reached 3.3 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 30 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and polycondensed at 230°C for 4 hours under nitrogen purge to obtain antibacterial regenerated polyamide 6.

[0079] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 20,000 g / mol, a relative viscosity of 2.7, a melting point of 219.5°C, a PDI of 1.5, a hot water extractable content of 3 wt%, and a cyclic dimer content of 0.5 wt%.

[0080] Comparative Example 1

[0081] A method for preparing antibacterial regenerated polyamide 6 is basically the same as that in Example 1, except that the conditions of the hydrolysis reaction are different, so that the number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer obtained in step (2) is 2000 g / mol.

[0082] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 18,000 g / mol, a relative viscosity of 2.5, a melting point of 219.0°C, a PDI of 1.8, a hot water extractable content of 5.2 wt%, and a cyclic dimer content of 1.3 wt%.

[0083] Compared with Example 1, the hot water extractable content and the cyclic dimer content of Comparative Example 1 increased. This is because the number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer are relatively low, which will produce more hot water extractables. During the evaporation of water in the equilibrium kettle, a portion of the hot water extractables will be taken away, but most of it will still remain in the system, resulting in an increase in the hot water extractable content and the cyclic dimer content in the system during the subsequent polymerization process.

[0084] Comparative Example 2

[0085] A method for preparing antibacterial regenerated polyamide 6 is basically the same as that in Example 1, except that the conditions of the hydrolysis reaction are different, so that the number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer prepared in step (2) is 8000 g / mol.

[0086] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 26,000 g / mol, a relative viscosity of 3.2, a melting point of 221.0°C, a PDI of 3.2, a hot water extractable content of 3.2 wt%, and a cyclic dimer content of 0.7 wt%.

[0087] Compared with Example 1, the PDI of Comparative Example 2 is larger, and the hot water extractable content and the cyclic dimer content are high. This is because the number average molecular weight of the first polyamide 6 mesopolymer and the second polyamide 6 mesopolymer in Comparative Example 2 is too high, resulting in the number average molecular weight of the antibacterial functional polyamide 6 mesopolymer obtained by reacting the second polyamide 6 mesopolymer also being high, making the melt viscosity of the antibacterial functional polyamide 6 mesopolymer and the first polyamide 6 mesopolymer high during copolymerization, making it difficult to carry out uniform copolymerization. This causes the antibacterial functional polyamide 6 mesopolymer to be unevenly distributed on the antibacterial recycled polyamide 6, resulting in poor inhibition of the backbiting reaction of the antibacterial recycled polyamide 6 molecular chain (that is, the antibacterial functional polyamide 6 mesopolymer is unevenly distributed on the antibacterial recycled polyamide 6, leaving some amide bonds with a larger activity space). Therefore, while the PDI increases, the hot water extractable content and the cyclic dimer content increase.

[0088] Example 2

[0089] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0090] (1) Preparation of raw materials;

[0091] Waste polyamide 6 products;

[0092] The antibacterial monomer is polyaminopropyl biguanide (CAS No.: 133029-32-0, specification model: purity 99%);

[0093] The end group modification agent is L-glutamic acid (CAS number: 56-86-0, specification model: purity 99%);

[0094] water;

[0095] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:2 in a hydrolysis kettle at 190°C for 100 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, obtaining a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 10% of the mass of the waste polyamide 6 product;

[0096] The number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer obtained was 5500 g / mol;

[0097] (3) The second polyamide 6 midpolymer is diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 15% is added, and the mixture is reacted at 162°C and 0.77 MPa for 70 min. An aqueous solution of an end group modifier with a mass fraction of 6% is then added, and the mixture is reacted at 162°C and 0.64 MPa for 110 min to obtain an antibacterial functional polyamide 6 midpolymer; wherein the mass of the antibacterial monomer is 20 wt% of the mass of the waste polyamide 6 product; and the mass of the end group modifier is 6 wt% of the mass of the waste polyamide 6 product.

[0098] The number average molecular weight of the obtained antibacterial functional polyamide 6 mesomer is 3800 g / mol;

[0099] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 215°C until the pressure reached 3 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 27 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and the polycondensation reaction was carried out at 233°C for 3.6 hours under nitrogen purge to obtain the antibacterial regenerated polyamide 6.

[0100] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 18,000 g / mol, a relative viscosity of 2.5, a melting point of 219.0°C, a PDI of 1.8, a hot water extractable content of 2.8 wt%, and a cyclic dimer content of 0.4 wt%.

[0101] Example 3

[0102] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0103] (1) Preparation of raw materials;

[0104] Waste polyamide 6 products;

[0105] The antibacterial monomer is aminoguanidine bicarbonate (CAS No.: 2582-30-1, specification model: purity 98.0%);

[0106] The end group modifier is L-lysine (CAS No.: 56-87-1, specification model: purity 98.0%);

[0107] water;

[0108] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:3 in a hydrolysis kettle at 200°C for 80 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 20% of the mass of the waste polyamide 6 product;

[0109] The number average molecular weight of the prepared first polyamide 6 mesomer and the second polyamide 6 mesomer is 5000 g / mol;

[0110] (3) The second polyamide 6 intermediate polymer was diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 20% was added, and the reaction was carried out at 164°C and 0.74 MPa for 80 minutes. Then, an aqueous solution of an end group modifier with a mass fraction of 7% was added, and the reaction was carried out at 163°C and 0.66 MPa for 100 minutes to obtain an antibacterial functional polyamide 6 intermediate polymer; wherein the mass of the antibacterial monomer is 30wt% of the mass of the waste polyamide 6 product; the mass of the end group modifier is 7wt% of the mass of the waste polyamide 6 product;

[0111] The number average molecular weight of the obtained antibacterial functional polyamide 6 mesomer is 3400 g / mol;

[0112] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 220°C until the pressure reached 2.8 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 24 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and the polycondensation reaction was carried out at 236°C for 3.2 hours under argon purge to obtain antibacterial regenerated polyamide 6.

[0113] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 14000 g / mol, a relative viscosity of 2, a melting point of 218.0°C, a PDI of 2, a hot water extractable content of 2.6 wt%, and a cyclic dimer content of 0.3 wt%.

[0114] Example 4

[0115] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0116] (1) Preparation of raw materials;

[0117] Waste polyamide 6 products;

[0118] The antibacterial monomer is aminoguanidine carbonate (CAS number: 2582-30-1, specification model: purity 98.0%);

[0119] The end group modifier is glutamine (CAS No.: 3918-84-1, specification model: purity 98.0%);

[0120] water;

[0121] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:4 in a hydrolysis kettle at 210°C for 60 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, obtaining a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 21% of the mass of the waste polyamide 6 product;

[0122] The number average molecular weight of the prepared first polyamide 6 mesomer and the second polyamide 6 mesomer was 4500 g / mol;

[0123] (3) The second polyamide 6 intermediate polymer was diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 30% was added, and the mixture was reacted at 166°C and 0.72 MPa for 90 min. An aqueous solution of an end group modifier with a mass fraction of 8% was added, and the mixture was reacted at 164°C and 0.69 MPa for 90 min to obtain an antibacterial functional polyamide 6 intermediate polymer; wherein the mass of the antibacterial monomer was 35 wt% of the mass of the waste polyamide 6 product; and the mass of the end group modifier was 8 wt% of the mass of the waste polyamide 6 product.

[0124] The number average molecular weight of the prepared antibacterial functional polyamide 6 mesomer is 3000 g / mol;

[0125] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 225°C until the pressure reached 2.6 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 21 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and the polycondensation reaction was carried out at 239°C for 2.9 hours under a vacuum environment with a vacuum degree of 50 Pa to obtain antibacterial regenerated polyamide 6.

[0126] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 30,000 g / mol, a relative viscosity of 3.6, a melting point of 222.0°C, a PDI of 1.6, a hot water extractable content of 2 wt%, and a cyclic dimer content of 0.1 wt%.

[0127] Example 5

[0128] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0129] (1) Preparation of raw materials;

[0130] Waste polyamide 6 products;

[0131] The antibacterial monomer is aminoguanidine sulfate (CAS No.: 996-19-0, specification model: purity ≥98%);

[0132] The end group modifier is trimesic acid (CAS No.: 554-95-0, specification model: purity ≥99%);

[0133] water;

[0134] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:5 in a hydrolysis kettle at 220°C for 45 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, obtaining a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 30% of the mass of the waste polyamide 6 product;

[0135] The number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer obtained is 4000 g / mol;

[0136] (3) The second polyamide 6 intermediate polymer was diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 35% was added, and the reaction was carried out at 168°C and 0.68 MPa for 100 minutes. Then, an aqueous solution of an end group modifier with a mass fraction of 9% was added, and the reaction was carried out at 166°C and 0.72 MPa for 80 minutes to obtain an antibacterial functional polyamide 6 intermediate polymer; wherein the mass of the antibacterial monomer is 40wt% of the mass of the waste polyamide 6 product; the mass of the end group modifier is 9wt% of the mass of the waste polyamide 6 product;

[0137] The number average molecular weight of the prepared antibacterial functional polyamide 6 mesomer is 2800 g / mol;

[0138] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 230°C until the pressure reached 2.4 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 18 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and polycondensed at 242°C for 2.7 h under a vacuum environment with a vacuum degree of 150 Pa to obtain antibacterial regenerated polyamide 6.

[0139] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 28,000 g / mol, a relative viscosity of 3.4, a melting point of 221.5°C, a PDI of 2.2, a hot water extractable content of 2.1 wt%, and a cyclic dimer content of 0.1 wt%.

[0140] Example 6

[0141] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0142] (1) Preparation of raw materials;

[0143] Waste polyamide 6 products;

[0144] The antibacterial monomer is agmatine sulfate (CAS No.: 2482-00-0, specification model: purity ≥98%);

[0145] The end group modifier is trimesic acid (CAS No.: 554-95-0, specification model: purity ≥99%);

[0146] water;

[0147] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:6 in a hydrolysis kettle at 230°C for 30 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, obtaining a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 40% of the mass of the waste polyamide 6 product;

[0148] The number average molecular weight of the prepared first polyamide 6 mesomer and the second polyamide 6 mesomer was 3500 g / mol;

[0149] (3) The second polyamide 6 intermediate polymer was diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 40% was added, and the mixture was reacted at 169°C and 0.66 MPa for 110 min. An aqueous solution of an end group modifier with a mass fraction of 10% was then added, and the mixture was reacted at 168°C and 0.76 MPa for 70 min to obtain an antibacterial functional polyamide 6 intermediate polymer; wherein the mass of the antibacterial monomer was 45 wt% of the mass of the waste polyamide 6 product; and the mass of the end group modifier was 10 wt% of the mass of the waste polyamide 6 product.

[0150] The number average molecular weight of the prepared antibacterial functional polyamide 6 mesomer is 2400 g / mol;

[0151] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 235°C until the pressure reached 2.2 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 15 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and polycondensed at 245°C for 2.4 hours under a vacuum environment with a vacuum degree of 250 Pa to obtain antibacterial regenerated polyamide 6.

[0152] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 26,000 g / mol, a relative viscosity of 3.2, a melting point of 221.0°C, a PDI of 2.3, a hot water extractable content of 2.2 wt%, and a cyclic dimer content of 0.2 wt%.

[0153] Example 7

[0154] A method for preparing antibacterial regenerated polyamide 6, comprising the following steps:

[0155] (1) Preparation of raw materials;

[0156] Waste polyamide 6 products;

[0157] The antibacterial monomer is a mixture of 1-aminoguanidine (CAS No.: 141-83-3, specification model: purity ≥95%) and sulfaguanidine (CAS No.: 57-67-0, specification model: purity 98%) in a mass ratio of 1:1;

[0158] The end group modifier is trimesic acid (CAS No.: 554-95-0, specification model: purity ≥99%);

[0159] water;

[0160] (2) hydrolyzing the waste polyamide 6 product with water at a bath ratio of 1:7 in a hydrolysis kettle at 240°C for 20 minutes to obtain a waste polyamide 6 intermediate polymer, and dividing the waste polyamide 6 intermediate polymer into two parts, namely, a first polyamide 6 intermediate polymer and a second polyamide 6 intermediate polymer; wherein the mass of the second polyamide 6 intermediate polymer is 50% of the mass of the waste polyamide 6 product;

[0161] The number average molecular weight of the prepared first polyamide 6 mesomer and the second polyamide 6 mesomer is 3000 g / mol;

[0162] (3) The second polyamide 6 midpolymer is diverted to a modification kettle, and an aqueous solution of an antibacterial monomer with a mass fraction of 50% is added, and the mixture is reacted at 170°C and 0.62 MPa for 120 min. An aqueous solution of an end group modifier with a mass fraction of 10% is then added, and the mixture is reacted at 170°C and 0.79 MPa for 60 min to obtain an antibacterial functional polyamide 6 midpolymer; wherein the mass of the antibacterial monomer is 50 wt% of the mass of the waste polyamide 6 product; and the mass of the end group modifier is 10 wt% of the mass of the waste polyamide 6 product.

[0163] The number average molecular weight of the prepared antibacterial functional polyamide 6 mesomer is 2000 g / mol;

[0164] (4) The first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a balance kettle at a temperature of 240°C until the pressure reached 1.9 MPa, and then the pressure was released to 0.1 MPa at a pressure release rate of 10 kPa / h. Thereafter, the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer were placed in a polymerization kettle, and polycondensed at 250°C for 2 h in a vacuum environment with a vacuum degree of 300 Pa to obtain antibacterial regenerated polyamide 6.

[0165] The obtained antibacterial recycled polyamide 6 has a number average molecular weight of 24,000 g / mol, a relative viscosity of 3, a melting point of 220.5°C, a PDI of 2.5, a hot water extractable content of 2.4 wt%, and a cyclic dimer content of 0.3 wt%.

[0166] Example 8

[0167] A method for preparing antibacterial regenerated polyamide 6 fiber, comprising directly melt-spinning the antibacterial regenerated polyamide 6 of Example 1 using an FDY process to prepare the antibacterial regenerated polyamide 6 fiber;

[0168] The parameters of the FDY process include: spinning temperature 270°C, first godet speed 4000 m / min, second godet speed 6000 m / min, stretching ratio 1.5 times, cooling air temperature 15°C, cooling air speed 0.5 m / s, and cooling air relative humidity 60%.

[0169] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 16 dtex, the multifilament breaking strength is 5.0 cN / dtex, and the multifilament consists of 36 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 91.1%, 91.3% and 90.9%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 88.7%, 88.9% and 86.2%, respectively.

[0170] Comparative Example 3

[0171] A method for preparing antibacterial regenerated polyamide 6 fiber is basically the same as Example 8, except that the antibacterial regenerated polyamide 6 of Comparative Example 2 is directly melt-spun using the FDY process to prepare the antibacterial regenerated polyamide 6 fiber.

[0172] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 16 dtex, the breaking strength of the multifilament is 2.5 cN / dtex, and the multifilament consists of 36 monofilaments; the antibacterial rates of the prepared antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 86.0%, 86.8% and 83.2%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 82.1%, 81.5% and 78.9%, respectively.

[0173] Compared with Example 8, the breaking strength of the multifilament in Comparative Example 3 is low. This is because the PDI of the antibacterial regenerated polyamide 6 in Comparative Example 2 is too high. At the same processing temperature, the fluidity of the part with relatively low number average molecular weight in the polymer is too high or the melting of the part with relatively high number average molecular weight is incomplete, resulting in defects such as tiny holes or hard spots in the fiber. When subjected to force, these positions will break first, thereby reducing the overall strength of the fiber.

[0174] Compared with Example 8, the antibacterial performance of Comparative Example 3 is poor. This is because the number average molecular weight of the second polyamide 6 mesopolymer in Comparative Example 2 is too high, resulting in fewer exposed end carboxyl groups and fewer sites that can react with functional modification components, resulting in fewer components corresponding to the antibacterial monomers in the antibacterial functional polyamide 6 mesopolymer, and the antibacterial functional polyamide 6 mesopolymer in the antibacterial regenerated polyamide 6 of Comparative Example 2 is unevenly distributed.

[0175] Example 9

[0176] A method for preparing antibacterial regenerated polyamide 6 fiber, comprising directly melt-spinning the antibacterial regenerated polyamide 6 of Example 2 using a UDY process to prepare the antibacterial regenerated polyamide 6 fiber;

[0177] The parameters of the UDY process include: spinning temperature 280°C, spinning speed 700 m / min, cooling air temperature 20°C, cooling air speed 0.3 m / s, and cooling air relative humidity 75%.

[0178] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 7 dtex, the breaking strength of the multifilament is 3.0 cN / dtex, and the multifilament consists of 72 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 95.3%, 95.3% and 95.0%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 94.3%, 94.5% and 90.2%, respectively.

[0179] Example 10

[0180] A method for preparing antibacterial regenerated polyamide 6 fiber, comprising directly melt-spinning the antibacterial regenerated polyamide 6 of Example 3 using a POY process to prepare the antibacterial regenerated polyamide 6 fiber;

[0181] The parameters of the POY process include: spinning temperature 250°C, spinning speed 4500m / min, cooling air temperature 15°C, cooling air speed 0.4m / s, and cooling air relative humidity 60%.

[0182] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 10 dtex, the breaking strength of the multifilament is 4.0 cN / dtex, and the multifilament consists of 36 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 99.9%, 99.9% and 99.2%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 99.9%, 99.9% and 99.2%, respectively.

[0183] Example 11

[0184] A method for preparing antibacterial regenerated polyamide 6 fiber, comprising: using the HOY process, mixing the antibacterial regenerated polyamide 6 of Example 4 with polyamide 6 (product name: Yueyang Petrochemical PA6, brand: YH400) at a mass ratio of 1:4, and then melt-spinning the mixture to produce the antibacterial regenerated polyamide 6 fiber;

[0185] The parameters of the HOY process include: spinning temperature 270°C, spinning speed 6000m / min, cooling air temperature 15°C, cooling air speed 0.5m / s, and cooling air relative humidity 80%.

[0186] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 18 dtex, the breaking strength of the multifilament is 5.0 cN / dtex, and the multifilament consists of 36 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 90.0%, 90.0% and 90.2%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 88.0%, 88.0% and 85.0%, respectively.

[0187] Example 12

[0188] A method for preparing antibacterial regenerated polyamide 6 fiber, comprising mixing the antibacterial regenerated polyamide 6 of Example 5 with polyamide 6 (product name: Yueyang Petrochemical PA6, brand: YH400) at a mass ratio of 1:3 and then performing melt spinning; the melt spinning adopts a BCF process;

[0189] Among them, the parameters of the BCF process include: spinning temperature 245°C, cooling air temperature 20°C, cooling air speed 0.6 m / s, cooling air relative humidity 60%, feed roller temperature 80°C, stretching roller temperature 120°C, feed speed 1000 m / min, stretching speed 3500 m / min, stretching ratio 3.5 times, deformation hot air temperature 210°C, air injection pressure 300 kPa, winding speed 1200 m / min, and cooling air temperature 25°C.

[0190] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 7 dtex, the breaking strength of the multifilament is 3.5 cN / dtex, and the multifilament consists of 72 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 92.2%, 92.3% and 92.0%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 90.5%, 90.8% and 91.2%, respectively.

[0191] Example 13

[0192] A method for preparing antibacterial regenerated polyamide 6 fiber comprises mixing the antibacterial regenerated polyamide 6 of Example 6 with polyamide 6 (product name: Yueyang Petrochemical PA6, brand: YH400) at a mass ratio of 1:2 and then performing melt spinning; the melt spinning adopts an FDY process;

[0193] The FDY process parameters include: spinning temperature 260°C, first godet speed 4500m / min, second godet speed 6000m / min, stretching ratio 1.3 times, cooling air temperature 15°C, cooling air speed 0.7m / s, and cooling air relative humidity 80%.

[0194] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 13 dtex, the breaking strength of the multifilament is 4.5 cN / dtex, and the multifilament consists of 72 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 97.6%, 97.6% and 97.3%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 97.1%, 97.6% and 96.2%, respectively.

[0195] Example 14

[0196] A method for preparing an antibacterial regenerated polyamide 6 fiber, comprising: using a UDY process, mixing the antibacterial regenerated polyamide 6 of Example 7 with polyamide 6 (product name: Yueyang Petrochemical PA6, brand: YH400) at a mass ratio of 1:2, and then melt-spinning the mixture to produce the antibacterial regenerated polyamide 6 fiber;

[0197] The parameters of the UDY process include: spinning temperature 270°C, spinning speed 1000m / min, cooling air temperature 25°C, cooling air speed 0.8m / s, and cooling air relative humidity 60%;

[0198] The monofilament fineness of the prepared antibacterial regenerated polyamide 6 fiber is 8 dtex, the breaking strength of the multifilament is 3.8 cN / dtex, and the multifilament consists of 36 monofilaments; the antibacterial rates of the antibacterial regenerated polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans are 96.5%, 96.7% and 95.8%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans are 95.7%, 95.7% and 94.3%, respectively.

[0199] like Figure 7 As shown, the present invention also provides a preparation method of antibacterial regenerated polyamide 6 and a production device used for the application, the production device includes a hydrolysis kettle 1, a modification kettle 2, a balancing kettle I 3, a balancing kettle II 4, a polymerization kettle 5, a pelletizer 6, an extraction kettle 7, a dryer 8, a storage bin 9, a spinning device 10, a condensed water tank 11, a two-way distribution valve 12, a metering valve 13, a pipeline I 14, a pipeline II 15, a pipeline III 16, a pipeline IV 17, a pipeline V 18, a pipeline VI 19, a pipeline VII 20, a pipeline VIII 21, a pipeline IX 22, a pipeline X 23, a pipeline XI and a pipeline XII;

[0200] The number of the two-way distributing valves 12 is 2, and the number of the metering valves 13 is 3;

[0201] The hydrolysis reactor 1 and the modification reactor 2 are connected via a pipeline I 14, the modification reactor 2 is connected to the balancing reactor I 3 via a pipeline III 16, and the bottom of the balancing reactor I 3 is connected to the polymerization reactor 5 via a pipeline IV 17; a metering valve 13 is provided on the pipeline IV 17;

[0202] A two-way distributing valve 12 is provided on the pipeline I 14, and the balancing reactor II 4 is connected to the two-way distributing valve 12 via the pipeline II 15; the balancing reactor II 4 is connected to the polymerization reactor 5 via the pipeline V 18; a metering valve 13 is provided on the pipeline V 18;

[0203] The upper part of the balance kettle I 3 is connected to the condensation water tank 11 through the pipeline XI, and the balance kettle II 4 is connected to the condensation water tank 11 through the pipeline XII;

[0204] The bottom of the polymerization reactor 5 is connected to the pelletizer 6 via a pipeline VI 19; a metering valve 13 is provided on pipeline VI 19; the pelletizer 6 is connected to the extraction reactor 7 via a pipeline VII 20, and the extraction reactor 7 is connected to the dryer 8 via a pipeline VIII 21; the dryer 8 is connected to the storage bin 9 via a pipeline IX 22. A two-way distributing valve 12 is provided on pipeline IX 22, and the spinning device 10 is connected to the two-way distributing valve 12 via a pipeline X 23.

[0205] The usage process is as follows: waste polyamide 6 is hydrolyzed into polyamide 6 intermediate polymer in the hydrolysis kettle 1, and then the waste polyamide 6 intermediate polymer is divided into two parts through the two-way distribution valve 12 on the pipeline I14, namely the first polyamide 6 intermediate polymer and the second polyamide 6 intermediate polymer; the second polyamide 6 intermediate polymer is diverted to the modification kettle 2 to react with the antibacterial monomer and the end group modifier to generate antibacterial functional polyamide 6 intermediate polymer, and the antibacterial functional polyamide 6 intermediate polymer is then transported to the balancing kettle I3 to remove moisture, and then transported to the polymerization kettle 5. At the same time, the first polyamide 6 intermediate polymer on the other side is transported to the balancing kettle II 4 to remove moisture, and then transported to the polymerization kettle 5. Then, the first polyamide 6 intermediate polymer and the antibacterial functional polyamide 6 intermediate polymer react in the polymerization kettle 5 to generate antibacterial regenerated polyamide 6, and the antibacterial regenerated polyamide 6 then passes through the pelletizer 6, the extraction kettle 7, and the dryer 8 in sequence. When the mass of the second polyamide 6 intermediate polymer is 21-50% of the mass of the waste polyamide 6 product, the pipeline IX is adjusted. The two-way distribution valve 12 on 22 allows the antibacterial regenerated polyamide 6 to be directly input into the storage bin 9 for storage after being dried in the dryer 8. If it is later desired to be spun, it can be mixed with the polyamide 6 and melt-spun. When the mass of the polymer in the second polyamide 6 is 5-20% of the mass of the waste polyamide 6 product, the two-way distribution valve 12 on the pipeline IX 22 is adjusted so that the antibacterial regenerated polyamide 6 can be directly input into the storage bin 9 for storage after being dried in the dryer 8 or directly input into the spinning equipment 10 for spinning; wherein, the content of the polymer in the second polyamide 6 can be regulated by the two-way distribution valve 12 set on the pipeline I 14. Furthermore, the ratio of the polymer in the first polyamide 6 to the polymer in the antibacterial functional polyamide 6 in the polymerization kettle 5 can also be accurately regulated by the metering valve 13 on the pipeline IV17 and the metering valve 13 set on the pipeline V18.

[0206] The use of this production device can unify the hydrolysis process, functionalization and repolymerization into a continuous process, and through the distribution of polymers in polyamide 6, the preparation of antibacterial recycled polyamide 6 masterbatch and antibacterial recycled polyamide 6 chips can be achieved (the chips can be directly spun, and the masterbatch needs to be blended with polyamide 6), realizing the high value and diversified utilization of recycled polyamide 6.

Claims

1. A method for preparing antibacterial regenerated polyamide 6, characterized in that: The first polyamide 6 mesomer is subjected to a condensation reaction with the antibacterial functional polyamide 6 mesomer to obtain the antibacterial regenerated polyamide 6; The antibacterial functional polyamide 6 midipolymer is formed by reacting a second polyamide 6 midipolymer, an antibacterial monomer, and an end group modifier; the antibacterial monomer contains an amino group; the end group modifier contains a carboxyl group; the end carboxyl group of the second polyamide 6 midipolymer undergoes an amidation reaction with the amino group of the antibacterial monomer, and the end amino group of the second polyamide 6 midipolymer undergoes an amidation reaction with the carboxyl group of the end group modifier; The antimicrobial monomer is guanidine salt or chitosan; The terminal group modification agent is asparagine, glutamic acid, lysine, glutamine or trimesic acid; The number average molecular weight of the first polyamide 6 mesomer and the second polyamide 6 mesomer is 3000-6000 g / mol.

2. The method for preparing an antibacterial regenerated polyamide 6 according to claim 1, characterized in that: The guanidine salt is one or more of polyaminopropyl biguanide, aminoguanidine bicarbonate, aminoguanidine carbonate, aminoguanidine sulfate, agmatine sulfate, 1-aminoformylguanidine, sulfaguanidine, 1-o-tolylbiguanide, N-(2-methoxyethyl)guanidine, isoquinoline sulfate and guanidine hydrochloride.

3. The method for preparing an antibacterial regenerated polyamide 6 according to claim 2, characterized in that: The preparation process of the antibacterial functional polyamide 6 mesomer is as follows: the second polyamide 6 mesomer is diverted to a modification kettle, an aqueous solution of an antibacterial monomer is added, and the mixture is reacted at 160-170°C and 0.62-0.79 MPa for 60-120 minutes, and an aqueous solution of an end group modifier is added, and the mixture is reacted at 160-170°C and 0.62-0.79 MPa for 60-120 minutes to obtain the antibacterial functional polyamide 6 mesomer, wherein the mass fraction of the aqueous solution of the antibacterial monomer is 10%-50%, the mass fraction of the aqueous solution of the end group modifier is 5%-10%, and the number average molecular weight of the antibacterial functional polyamide 6 mesomer is 2000-4000 g / mol.

4. The method for preparing an antibacterial regenerated polyamide 6 according to claim 1, characterized in that: The polycondensation reaction is carried out in a polymerization kettle at a temperature of 230-250°C for 2-4 hours. Nitrogen or inert gas is purged during the polycondensation reaction. Alternatively, the polycondensation reaction is carried out in a vacuum environment with a vacuum degree of 50-300 Pa.

5. The method for preparing antibacterial regenerated polyamide 6 according to claim 4, characterized in that: Before the first polyamide 6 mesomer and the antibacterial functional polyamide 6 mesomer are put into the polymerization kettle, they are first put into a balance kettle at a temperature of 210-240°C until the pressure reaches 1.9-3.3MPa, and then the pressure is released to 0.1MPa at a pressure release rate of 10-30kPa / h.

6. The method for preparing an antibacterial regenerated polyamide 6 according to any one of claims 1 to 5, characterized in that: The preparation process of the first polyamide 6 mesopolymer and the second polyamide 6 mesopolymer is as follows: waste polyamide 6 products are hydrolyzed with water in a hydrolysis kettle at 180-240°C for 20-120 minutes to obtain waste polyamide 6 mesopolymer, and the waste polyamide 6 mesopolymer is divided into two parts to obtain the first polyamide 6 mesopolymer and the second polyamide 6 mesopolymer; the second polyamide 6 mesopolymer is entirely used to prepare antibacterial functional polyamide 6 mesopolymer, and the first polyamide 6 mesopolymer and the antibacterial functional polyamide 6 mesopolymer are entirely used to prepare antibacterial recycled polyamide 6; the mass of the antibacterial monomer is 10-50wt% of the mass of the waste polyamide 6 products, and the mass of the end group modifier is 5-10wt% of the mass of the waste polyamide 6 products.

7. The method for preparing antibacterial regenerated polyamide 6 according to claim 6, characterized in that: The mass of the second polyamide 6 intermediate is 5-20% of the mass of the waste polyamide 6 product.

8. The method for preparing antibacterial regenerated polyamide 6 according to claim 6, characterized in that: The mass of the second polyamide 6 polymer is 21-50% of the mass of the waste polyamide 6 product.

9. An antibacterial recycled polyamide 6, characterized in that: The antibacterial recycled polyamide 6 is prepared by the preparation method of claim 7; the antibacterial recycled polyamide 6 has a number average molecular weight of 14000-30000 g / mol, a relative viscosity of 2.0-3.6, a melting point of 218.0-222.0°C, a PDI of 1.5-2.5, a hot water extractable content of 2.0-3.0wt%, and a cyclic dimer content of 0.1-0.5wt%.

10. An antibacterial recycled polyamide 6, characterized in that: The antibacterial recycled polyamide 6 is prepared by the preparation method of claim 8; the antibacterial recycled polyamide 6 has a number average molecular weight of 14000-30000 g / mol, a relative viscosity of 2.0-3.6, a melting point of 218.0-222.0°C, a PDI of 1.5-2.5, a hot water extractable content of 2.0-3.0wt%, and a cyclic dimer content of 0.1-0.5wt%.

11. A method for preparing antibacterial regenerated polyamide 6 fiber, characterized in that: The antibacterial regenerated polyamide 6 according to claim 9 is directly melt-spinned, or the antibacterial regenerated polyamide 6 according to claim 10 is mixed with polyamide 6 in a mass ratio of 1:2-4 and then melt-spinned to obtain antibacterial regenerated polyamide 6 fiber; Melt spinning uses FDY, UDY, POY, HOY or BCF processes; The FDY process parameters include: spinning temperature 240-280°C, first godet speed 4000-4500 m / min, second godet speed 5000-6000 m / min, stretching ratio 1.1-1.5 times, cooling air temperature 15-25°C, cooling air speed 0.5-1 m / s, cooling air relative humidity 60%-90%; The parameters of the UDY process include: spinning temperature 240-280°C, spinning speed 700-1500m / min, cooling air temperature 20-30°C, cooling air speed 0.3-1m / s, cooling air relative humidity 60%-80%; The parameters of the POY process include: spinning temperature 240-280°C, spinning speed 4000-4500m / min, cooling air temperature 15-25°C, cooling air speed 0.3-0.6m / s, cooling air relative humidity 60%-80%; The parameters of the HOY process include: spinning temperature 240-280°C, spinning speed 4500-6000m / min, cooling air temperature 15-20°C, cooling air speed 0.3-0.5m / s, cooling air relative humidity 80%-90%; The BCF process parameters include: spinning temperature 240-280°C, cooling air temperature 20-30°C, cooling air speed 0.3-1m / s, cooling air relative humidity 60%-80%, feed roller temperature 60-120°C, stretching roller temperature 100-190°C, feed speed 300-1000m / min, stretching speed 1000-3500m / min, stretching ratio 3.5-5 times, deformation hot air temperature 190-230°C, air injection pressure 196-490kPa, winding speed 600-3000m / min, cooling air temperature 25°C; The antibacterial recycled polyamide 6 fiber has a monofilament fineness of 0.2-18 dtex and a multifilament breaking strength of 3.0-5.0 cN / dtex. The multifilament consists of 36 or 72 monofilaments. The antibacterial rates of antibacterial recycled polyamide 6 fiber against Escherichia coli, Staphylococcus aureus and Candida albicans were 90.0-99.9%, 90.0-99.9% and 90.0-99.2%, respectively. After washing 50 times, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans were 88.0-99.9%, 88.0-99.9% and 85.0-99.2%, respectively.

Images