High-strength anti-ultraviolet regenerated PET fiber and preparation method thereof

Abstract

The invention provides a high-strength anti-ultraviolet regenerated PET fiber and a preparation method thereof. The preparation method comprises the following steps: in a nitrogen atmosphere, dissolving 2, 2 '-methylenebis [6-(benzotriazolyl)-tetramethylbutylphenol] and hexamethylene diisocyanate in N-methyl pyrrolidone, adding a catalyst for reaction, then heating to remove residual monomers, cooling, dropwise adding into ice methanol to separate out a product, washing, and carrying out vacuum drying to obtain an anti-ultraviolet auxiliary agent; the preparation method comprises the following steps: dissolving an anti-ultraviolet aid and hexamethylenediamine in an aprotic solvent, adding a catalyst, carrying out condensation reaction in a nitrogen atmosphere, and carrying out centrifugal washing and vacuum drying to obtain the anti-ultraviolet composite chain extender, the preparation method comprises the following steps: mixing an anti-ultraviolet composite chain extender with recycled PET fragments, adding an antioxidant, a hydrolysis-resistant solution and a lubricant, and carrying out blending spinning through a double-screw extruder to obtain the high-strength anti-ultraviolet regenerated PET fiber. According to the invention, through anti-ultraviolet-chain extension chemical bonding, the bottleneck that the strength and the function of the regenerated PET fiber are difficult to synergistically improve is broken through.

Description

Technical Field

[0001] The invention relates to the technical field of PET regenerated fibers, in particular to a high-strength UV-resistant regenerated PET fiber and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate fiber, also known as PET fiber, is widely used in textiles, packaging, and other fields due to its excellent mechanical properties, chemical resistance, and recyclability. With growing environmental awareness, the research and development of recycled PET fiber has attracted considerable attention. However, PET is susceptible to thermal degradation and hydrolysis during repeated recycling, leading to molecular chain breakage and a decrease in molecular weight, significantly reducing the mechanical properties of the recycled fiber. Furthermore, conventional recycled PET fiber lacks UV resistance, limiting its application in high-value-added applications such as outdoor textiles.

[0003] Currently, efforts to improve the performance of recycled PET fibers primarily focus on chain extender modification and blending enhancement techniques. For example, isocyanate chain extenders are used to repair PET molecular chains to improve mechanical properties, but this approach struggles to simultaneously impart fiber functionality. Directly adding UV inhibitors, such as benzotriazole compounds, through physical blending can lead to poor dispersibility, insufficient compatibility with the matrix, and low spinning stability. Furthermore, small molecule additives are prone to migration, making sustained UV resistance difficult. Furthermore, the high-temperature tolerance of UV inhibitors in existing technologies is mismatched with the melt processing temperature of PET, which can easily lead to decomposition or failure.

[0004] Therefore, there is an urgent need to develop an integrated preparation method that can take into account both the repair of the mechanical properties of recycled PET fibers and their long-term anti-ultraviolet function. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides a high-strength UV-resistant regenerated PET fiber and a preparation method thereof. Through molecular structure design, chemical bonding between the UV-resistant group and the chain extender is achieved, thereby improving the fiber strength while giving it stable UV-resistant properties, solving the problems raised in the above-mentioned background technology.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] According to a first aspect of the present invention, there is provided a method for preparing high-strength UV-resistant regenerated PET fiber, comprising the following steps:

[0010] (1) Under a nitrogen atmosphere, 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] and hexamethylene diisocyanate are dissolved in N-methylpyrrolidone, a catalyst is added to react, and then the temperature is raised to remove residual monomers. After cooling, the product is dropped into ice methanol to precipitate, washed, and vacuum dried to obtain an anti-ultraviolet additive;

[0011] (2) dissolving the anti-ultraviolet auxiliary agent and hexamethylenediamine in an aprotic solvent, adding a catalyst, carrying out a condensation reaction under a nitrogen atmosphere, centrifuging and washing, and vacuum drying to obtain an anti-ultraviolet composite chain extender;

[0012] (3) The anti-ultraviolet composite chain extender is mixed with recycled PET fragments, and then an antioxidant, an anti-hydrolysis liquid and a lubricant are added, and the mixture is blended and spun through a twin-screw extruder at a zoned temperature and a high shear screw to obtain high-strength anti-ultraviolet recycled PET fibers.

[0013] Preferably, in step (1) and step (2), the catalyst is selected from at least one of dibutyltin dilaurate, bismuth isooctanoate, triethylenediamine, and isopropyl tris(dioctylpyrophosphate) titanate.

[0014] Preferably, in step (1), the mass ratio of the 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol], hexamethylene diisocyanate and catalyst is 1:0.04-0.2:0.005-0.02.

[0015] Preferably, in step (1), the reaction temperature is 80-90° C. and the reaction time is 2-8 h;

[0016] The temperature for removing residual monomers is 100-110°C;

[0017] The vacuum drying temperature is 50-60°C.

[0018] Preferably, in step (2), the mass ratio of the anti-ultraviolet auxiliary agent, hexamethylenediamine and catalyst is 10:1-3:0.1-0.5.

[0019] Preferably, in step (2), the aprotic solvent is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, methyl ethyl ketone, and chloroform.

[0020] Preferably, in step (2), the condensation reaction temperature is 70-90° C. and the time is 2-8 h;

[0021] The vacuum drying temperature is 50-60°C.

[0022] Preferably, in step (3), the anti-ultraviolet composite chain extender is 0.1% to 2% by mass, and the recycled PET fragments are 98% to 99.9% by mass;

[0023] The mass ratio of the recycled PET fragments to the antioxidant, anti-hydrolysis agent and lubricant is 1: 0.001-0.005: 0.002-0.008: 0.0005-0.003.

[0024] Preferably, the temperature of the blended spinning is 260-290° C., and the screw speed of the twin-screw extruder is 100-500 rpm.

[0025] According to a second aspect of the present invention, there is provided a high-strength UV-resistant regenerated PET fiber obtained according to the above preparation method, wherein the fiber has a tensile strength ≥97 MPa, an intrinsic viscosity ≥1.08 dL / g, and an UV protection factor ≥42.

[0026] (3) Beneficial effects

[0027] The present invention provides a high-strength UV-resistant regenerated PET fiber and a preparation method thereof. It has the following beneficial effects:

[0028] (1) This scheme provides a method for preparing high-strength UV-resistant regenerated PET fiber, in which an anti-UV group containing benzotriazole is introduced into the chain extender molecular chain through chemical bonding. The chain extender reacts with the PET end group to repair the molecular chain, and the anti-UV group is anchored to the PET main chain, which can avoid the migration and precipitation of small molecules. The group is evenly dispersed and has good compatibility with the matrix, so that the PET fiber has long-lasting UV resistance and is resistant to washing and long-term use.

[0029] (2) This scheme provides a method for preparing high-strength UV-resistant recycled PET fiber. The prepared UV-resistant composite chain extender contains a condensation product of hexamethylene diisocyanate and hexamethylenediamine. The isocyanate group reacts with the terminal carboxyl / hydroxyl groups produced by PET degradation to repair broken molecular chains and improve the molecular weight and chain segment regularity, so that the strength and intrinsic viscosity of the recycled PET fiber are close to those of virgin PET.

[0030] (3) This scheme provides a method for preparing high-strength UV-resistant recycled PET fiber, in which the benzotriazole UV-resistant group is connected to the methylene bisphenol rigid chain extender skeleton through a covalent bond, thereby improving the thermal stability and allowing the chain extender to remain stable when blended at 280°C in a twin-screw melt. The UV-resistant function is not lost during the melt spinning process, and the fiber processing stability is high. DETAILED DESCRIPTION

[0031] In order to better illustrate the content of the present invention, a detailed description is given below in conjunction with specific embodiments.

[0032] Example 1

[0033] A method for preparing high-strength UV-resistant regenerated PET fiber comprises the following steps:

[0034] Preparation of the anti-UV additive: Under a nitrogen atmosphere, 100 g of 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] and 8 g of hexamethylene diisocyanate were dissolved in 500 mL of N-methylpyrrolidone, and 2 g of dibutyltin dilaurate was added. The mixture was reacted at 85°C for 5 h, and the temperature was raised to 105°C to remove residual monomers. After cooling, icy methanol was added to precipitate, which was filtered, washed three times with water / methanol, and dried in vacuo at 55°C for 12 h to obtain a white powder anti-UV additive.

[0035] Preparation of an anti-UV composite chain extender: 10 g of an anti-UV additive and 2 g of hexamethylenediamine were dissolved in 100 mL of N,N-dimethylformamide, and 0.5 g of bismuth isooctanoate was added. The mixture was condensed at 90°C under nitrogen for 6 h to form a urea bond. The product was centrifuged and washed three times with acetone to remove free hexamethylenediamine. The product was then dried under vacuum at 60°C for 10 h to obtain a light yellow anti-UV composite chain extender.

[0036] Co-blending spinning: 99.5 kg of recycled PET chips were mixed with 0.5 kg of an anti-UV composite chain extender, 0.5 kg of Irganox 1010, 0.8 kg of Stabaxol P100, and 0.3 kg of calcium stearate. The mixture was melt-blended and spun in a twin-screw extruder at a temperature of 260°C in zone 1, 275°C in zone 2, and 285°C in zone 3. The screw speed was 300 rpm to obtain recycled PET fiber.

[0037] Example 2

[0038] A method for preparing high-strength UV-resistant regenerated PET fiber comprises the following steps:

[0039] Preparation of the anti-UV additive: Under a nitrogen atmosphere, 100 g of 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] and 12 g of hexamethylene diisocyanate were dissolved in 500 mL of N-methylpyrrolidone, and 0.5 g of isopropyl tris(dioctyl pyrophosphate acyloxy) titanate was added and reacted at 90°C for 3 h. The temperature was raised to 110°C to remove residual monomers. After cooling, icy methanol was added to precipitate, which was filtered, washed three times with water / methanol, and dried in vacuo at 55°C for 12 h to obtain a white powdery anti-UV additive.

[0040] Preparation of an anti-UV composite chain extender: Dissolve 10 g of an anti-UV additive and 3 g of hexamethylenediamine in 100 mL of acetone, then add 0.1 g of bismuth isooctanoate. Incubate at 80°C under nitrogen for 6 h to form a urea bond. Centrifuge the product, wash it three times with acetone to remove free hexamethylenediamine, and dry it in a vacuum at 60°C for 10 h to obtain a light yellow anti-UV composite chain extender.

[0041] Co-blending spinning: 98.8 kg of recycled PET chips were mixed with 1.2 kg of an anti-UV composite chain extender, 0.1 kg of Irganox 1010, 0.2 kg of Stabaxol P100, and 0.05 kg of calcium stearate. The mixture was melt-blended and spun in a twin-screw extruder at a temperature of 260°C in zone 1, 275°C in zone 2, and 285°C in zone 3. The screw speed was 300 rpm to obtain recycled PET fiber.

[0042] Example 3

[0043] A method for preparing high-strength UV-resistant regenerated PET fiber comprises the following steps:

[0044] Preparation of the anti-UV additive: Under a nitrogen atmosphere, 100 g of 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] and 8 g of hexamethylene diisocyanate were dissolved in 500 mL of N-methylpyrrolidone, and 1 g of triethylenediamine was added. The mixture was reacted at 80°C for 8 h, and the temperature was raised to 105°C to remove residual monomers. After cooling, icy methanol was added to precipitate, which was filtered, washed three times with water / methanol, and dried in vacuo at 55°C for 12 h to obtain a white powder anti-UV additive.

[0045] Preparation of an anti-UV composite chain extender: 10 g of an anti-UV additive and 2 g of hexamethylenediamine were dissolved in 100 mL of dimethyl sulfoxide, and 0.3 g of bismuth isooctanoate was added. The mixture was condensed at 80°C under nitrogen for 4 h to form a urea bond. The product was centrifuged and washed three times with acetone to remove free hexamethylenediamine. The product was then dried under vacuum at 60°C for 10 h to obtain a light yellow anti-UV composite chain extender.

[0046] Co-blending spinning: 99.7 kg of recycled PET chips were mixed with 0.3 kg of an anti-UV composite chain extender, 0.2 kg of Irganox 1010, 0.2 kg of Stabaxol P100, and 0.08 kg of calcium stearate. The mixture was melt-blended and spun in a twin-screw extruder at a temperature of 260°C in zone 1, 275°C in zone 2, and 285°C in zone 3. The screw speed was 300 rpm to obtain recycled PET fibers.

[0047] Comparative Example 1

[0048] A method for preparing regenerated PET fiber comprises the following steps:

[0049] 99.5 kg of recycled PET chips were mixed with 0.3 kg of Irganox 1010, 0.4 kg of Stabaxol P100 and 0.1 kg of calcium stearate, and melt-blended and spun in a twin-screw extruder at a temperature of 260°C in zone 1, 275°C in zone 2, and 285°C in zone 3. The screw speed was 300 rpm to obtain recycled PET fibers.

[0050] Comparative Example 2

[0051] A method for preparing regenerated PET fiber comprises the following steps:

[0052] 0.5 kg of 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] was mixed with 99.5 kg of recycled PET chips and melt-blended and spun through a twin-screw extruder. The temperature of zone 1 was 260°C, the temperature of zone 2 was 275°C, the temperature of zone 3 was 285°C, and the screw speed was 300 rpm to obtain recycled PET fiber.

[0053] Comparative Example 3

[0054] The preparation method of this comparative example is the same as that of Example 1, except that, during the preparation of the anti-ultraviolet auxiliary agent, the amount of hexamethylene diisocyanate added is 3 g.

[0055] The regenerated PET fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests, including tensile strength testing according to the test standard of GB / T 14344-2022, intrinsic viscosity testing according to the test standard of GB / T 14190-2017, and ultraviolet protection factor testing according to the test standard of GB / T 18830-2009. The ultraviolet protection factor was tested after 50 standard washes. The test results are shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] According to the data in Table 1, the present invention can significantly improve the mechanical properties and anti-ultraviolet durability of the recycled PET fiber by chemically bonding the anti-ultraviolet group and the chain extender. Compared with not adding the anti-ultraviolet composite chain extender, adding the anti-ultraviolet agent by physical blending, and too low a proportion of the chain extender, the performance of the recycled PET will be greatly reduced. Therefore, the present invention can break through the bottleneck of the synergistic improvement of the strength and function of the recycled PET fiber through the integrated molecular design of anti-ultraviolet and chain extension, combined with chemical bonding and dynamic processing control.

[0060] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-strength UV-resistant regenerated PET fiber, characterized in that: The following steps are involved: (1) Under a nitrogen atmosphere, 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol] and hexamethylene diisocyanate are dissolved in N-methylpyrrolidone, a catalyst is added to react, and then the temperature is raised to remove residual monomers. After cooling, the product is dropped into ice methanol to precipitate, washed, and vacuum dried to obtain an anti-ultraviolet additive; (2) dissolving the anti-ultraviolet auxiliary agent and hexamethylenediamine in an aprotic solvent, adding a catalyst, carrying out a condensation reaction under a nitrogen atmosphere, centrifuging and washing, and vacuum drying to obtain an anti-ultraviolet composite chain extender; (3) The anti-ultraviolet composite chain extender is mixed with recycled PET fragments, and then an antioxidant, an anti-hydrolysis liquid and a lubricant are added, and the mixture is blended and spun through a twin-screw extruder at a zoned temperature and a high shear screw to obtain high-strength anti-ultraviolet recycled PET fibers.

2. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (1) and step (2), the catalyst is selected from at least one of dibutyltin dilaurate, bismuth isooctanoate, triethylenediamine, and isopropyl tris(dioctyl pyrophosphate) titanate.

3. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (1), the mass ratio of the 2,2'-methylenebis[6-(benzotriazolyl)-tetramethylbutylphenol], hexamethylene diisocyanate and catalyst is 1:0.04-0.2:0.005-0.

02.

4. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (1), the reaction temperature is 80-90° C. and the reaction time is 2-8 h; The temperature for removing residual monomers is 100-110°C; The vacuum drying temperature is 50-60°C.

5. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (2), the mass ratio of the anti-ultraviolet auxiliary agent, hexamethylenediamine and catalyst is 10:1-3:0.1-0.

5.

6. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (2), the aprotic solvent is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, methyl ethyl ketone, and chloroform.

7. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (2), the condensation reaction temperature is 70-90° C. and the time is 2-8 hours; The vacuum drying temperature is 50-60°C.

8. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: In step (3), the anti-ultraviolet composite chain extender is 0.1% to 2% by mass, and the recycled PET fragments are 98% to 99.9% by mass; The mass ratio of the recycled PET fragments to the antioxidant, anti-hydrolysis agent and lubricant is 1: 0.001-0.005: 0.002-0.008: 0.0005-0.

003.

9. The method for preparing a high-strength UV-resistant regenerated PET fiber according to claim 1, wherein: The temperature of the blended spinning is 260-290° C., and the screw speed of the twin-screw extruder is 100-500 rpm.

10. A high-strength UV-resistant regenerated PET fiber obtained by the preparation method according to any one of claims 1 to 9, characterized in that: Its tensile strength is ≥97MPa, its intrinsic viscosity is ≥1.08dL / g, and its UV protection factor is ≥42.

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