A method for preparing high-strength polyester fiber containing liquid crystal polymer

Abstract

The invention belongs to the technical field of polyester fibers and discloses a method for preparing a high-strength polyester fiber containing a liquid crystal polymer. 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane, a diol compound and a diisocyanate compound are reacted to obtain a polyester-polyurethane-based liquid crystal polymer. The polyester-polyurethane-based liquid crystal polymer is then melt-blended with polyethylene terephthalate, extruded, granulated and melt-spun to obtain a high-strength polyester fiber containing the liquid crystal polymer. The polyester-polyurethane-based liquid crystal polymer contains a benzoate structure, has good structural similarity with polyethylene terephthalate, improves the compatibility and dispersibility of the polyester-polyurethane-based liquid crystal polymer in the polyester fiber, and contains a flexible and heat-resistant organic siloxane structure and a thermally stable biphenyl group, which can significantly improve the tensile properties and heat resistance of the fiber.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester fibers, and in particular to a method for preparing high-strength polyester fibers containing liquid crystal polymers. Background Art

[0002] Polyethylene terephthalate (PET) and its fiber products have good strength, elasticity and heat resistance, and are widely used in textiles, construction machinery, automobile manufacturing and other fields. The development of high-performance polyester fibers is of great significance. Polyurethane is a type of polymer with high elasticity, good toughness and excellent strength. It can be made into high-performance fibers, foams, elastomers and other materials. By compounding polyurethane with polyethylene terephthalate, fibers, plastics and other products with better performance can be obtained.

[0003] Liquid crystal polymer is a new type of polymer material. When heated, it will become a liquid crystal form. It has the characteristics of high molecular weight and orderly orientation. It mainly includes polyurethane liquid crystal polymer, polyarylate liquid crystal polymer, azo liquid crystal polymer, etc. It can be used as a toughening agent and reinforcing material, and has broad application prospects in the toughening and strengthening modification of epoxy resin, polypropylene, polyester and other materials. Patent CN110184678B discloses that graphene and liquid crystal polyester are used as reinforcements and spun with materials such as PET, PEN, PPT, etc., and the resulting polymer fiber has good mechanical strength. However, this patent requires the additional addition of graphene and does not improve the heat resistance of the polymer fiber. Summary of the invention

[0004] The invention solves the problems of low strength, poor toughness and poor heat resistance of polyester fibers.

[0005] The technical solution of the present invention is: a method for preparing high-strength polyester fiber containing liquid crystal polymer:

[0006] Step S1, add N,N-dimethylformamide, 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane, a diol compound, a diisocyanate compound, and dibutyltin dilaurate into a flask, react in a nitrogen atmosphere, add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyester-polyurethane-based liquid crystal polymer.

[0007] Step S2, adding polyethylene terephthalate and polyester-polyurethane-based liquid crystal polymer into a twin-screw extruder for melt blending, extrusion, and granulation; then placing the granules in a melt spinning machine for spinning, and stretching them through a stretching machine to obtain high-strength polyester fibers containing liquid crystal polymers.

[0008] Preferably, in step S1, the reaction is carried out at 60-80° C. for 4-7 h.

[0009] Preferably, in step S1, the molar ratio of 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane, the diol compound, and the diisocyanate compound is (20-50):(50-80):100. The diisocyanate compound is toluene-2,4-diisocyanate or diphenylmethane-4,4'-diisocyanate. The structural formula of the diol compound is n is any integer from 2 to 6.

[0010] Preferably, the mass ratio of polyethylene terephthalate to polyester-polyurethane-based liquid crystal polymer is 100:(3-20).

[0011] Preferably, the temperature of zones 1-7 of the screw extruder is 240-280°C, and the screw speed is 40-100r / min; the temperature of zones 1-4 of the melt spinning machine is 270-300°C; the hot plate temperature of the drawing machine is 80-90°C, the hot plate temperature is 160-170°C, and the drawing multiple is 3.4-4 times.

[0012] Preferably, the preparation method of 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane comprises the following steps:

[0013] Step 1: Add toluene solvent, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 4-bromobenzoyl chloride and pyridine in a molar ratio of 100:(200-210):(200-230) into a flask, heat to 35-50°C and react for 8-18h, evaporate the solution by rotary evaporation, wash with water, and recrystallize the product in ethanol to obtain intermediate A.

[0014] Step 2: Add 1,4-dioxane solvent, p-hydroxyphenylboric acid, intermediate A, bis(triphenylphosphine)palladium dichloride and potassium carbonate aqueous solution into a flask, heat to 80-100° C. in a nitrogen atmosphere and react for 24-36 hours, rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane.

[0015] Preferably, in step 1, the molar ratio of p-hydroxyphenylboronic acid, intermediate A, bis(triphenylphosphine)palladium dichloride and potassium carbonate is (180-220):100:(2.8-4):(340-440).

[0016] Technical effect: The present invention uses pyridine as a catalyst to carry out an esterification reaction on 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 4-bromobenzoyl chloride, and then carries out a Suzuki coupling reaction with p-hydroxyphenylboric acid to obtain a novel 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane monomer containing a benzoate structure, and then carries out a polymerization reaction with a diol compound and a diisocyanate compound to obtain a polyester-polyurethane-based liquid crystal polymer. Finally, the polymer is melt-blended, extruded and melt-spun with polyethylene terephthalate to obtain a high-strength polyester fiber containing a liquid crystal polymer.

[0017] The polyester-polyurethane-based liquid crystal polymer of the present invention contains a benzoate structure and has a good structural similarity with polyethylene terephthalate, thereby improving the compatibility and dispersibility of the polyester-polyurethane-based liquid crystal polymer in polyester fibers, and will not affect the mechanical properties of the polyester fibers; at the same time, the liquid crystal polymer itself has good mechanical properties, high temperature resistance and other properties, and the polyester-polyurethane-based liquid crystal polymer contains a flexible and heat-resistant organic siloxane structure and a thermally stable biphenyl group, which is added to polyester fibers to significantly improve the tensile properties and heat resistance of the fibers, and show higher breaking strength, breaking elongation and thermal decomposition temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the reaction formula for preparing 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane.

[0019] Figure 2 It is the preparation reaction formula of polyester-polyurethane based liquid crystal polymer. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] (1) Add 50 mL of toluene solvent, 12 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 24 mmol of 4-bromobenzoyl chloride, and 27.6 mmol of pyridine to a flask, heat to 35° C. and react for 12 h. Rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain intermediate A.

[0023] (2) Add 70 mL of 1,4-dioxane solvent, 27 mmol of p-hydroxyphenylboric acid, 15 mmol of intermediate A, 0.42 mmol of bis(triphenylphosphine)palladium dichloride, and 30 mL of an aqueous solution containing 60 mmol of potassium carbonate into a flask, heat to 90° C. in a nitrogen atmosphere, react for 36 hours, rotary evaporate the solution, wash with water, and recrystallize the product from ethanol to obtain 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane.

[0024] (3) Add 200 mL of N,N-dimethylformamide, 20 mmol of 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane, 80 mmol of 1,6-hexanediol, 100 mmol of toluene-2,4-diisocyanate, and 0.15 g of dibutyltin dilaurate into a flask, heat to 70° C. in a nitrogen atmosphere, and react for 7 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyester-polyurethane-based liquid crystal polymer.

[0025] (4) 1000 g of polyethylene terephthalate and 30 g of polyester-polyurethane-based liquid crystal polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 40 r / min. The pellets are then placed in a melt spinning machine for spinning. The temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C. The pellets are stretched in a stretching machine. The temperature of the hot plate is 85° C., the temperature of the hot plate is 160° C., and the stretching ratio is 4 times. A high-strength polyester fiber containing a liquid crystal polymer is obtained.

[0026] Example 2

[0027] (1) Add 60 mL of toluene solvent, 12 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 25.2 mmol of 4-bromobenzoyl chloride, and 27.6 mmol of pyridine to a flask, heat to 35° C. and react for 18 h. Rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain intermediate A.

[0028] (2) Add 90 mL of 1,4-dioxane solvent, 33 mmol of p-hydroxyphenylboric acid, 15 mmol of intermediate A, 0.42 mmol of bis(triphenylphosphine)palladium dichloride, and 20 mL of an aqueous solution containing 66 mmol of potassium carbonate into a flask, heat to 80° C. in a nitrogen atmosphere, react for 36 h, rotary evaporate the solution, wash with water, and recrystallize the product from ethanol to obtain 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane.

[0029] (3) Add 300 mL of N,N-dimethylformamide, 35 mmol of 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane, 65 mmol of 1,4-butanediol, 100 mmol of diphenylmethane-4,4'-diisocyanate, and 0.2 g of dibutyltin dilaurate into a flask, heat to 60° C. in a nitrogen atmosphere, and react for 7 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyester-polyurethane-based liquid crystal polymer.

[0030] (4) 1000 g of polyethylene terephthalate and 30 g of polyester-polyurethane-based liquid crystal polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 40 r / min. The pellets are then placed in a melt spinning machine for spinning. The temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C. The pellets are stretched in a stretching machine. The temperature of the hot plate is 90° C., the temperature of the hot plate is 170° C., and the stretching ratio is 4 times. A high-strength polyester fiber containing a liquid crystal polymer is obtained.

[0031] Example 3

[0032] (1) Add 50 mL of toluene solvent, 12 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 24 mmol of 4-bromobenzoyl chloride, and 24 mmol of pyridine to a flask, heat to 50° C. and react for 8 h. Rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain intermediate A.

[0033] (2) Add 90 mL of 1,4-dioxane solvent, 30 mmol of p-hydroxyphenylboric acid, 15 mmol of intermediate A, 0.6 mmol of bis(triphenylphosphine)palladium dichloride, and 20 mL of an aqueous solution containing 51 mmol of potassium carbonate into a flask, heat to 100° C. in a nitrogen atmosphere, and react for 24 h. The solution is rotary evaporated, washed with water, and the product is recrystallized in ethanol to obtain 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane.

[0034] (3) Add 200 mL of N,N-dimethylformamide, 50 mmol of 1,3-bis(3-(biphenylpropyl)-1,1,3,3-tetramethyldisiloxane, 50 mmol of ethylene glycol, 100 mmol of toluene-2,4-diisocyanate, and 0.15 g of dibutyltin dilaurate into a flask, heat to 80° C. in a nitrogen atmosphere, and react for 3 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyester-polyurethane-based liquid crystal polymer.

[0035] (4) 1000 g of polyethylene terephthalate and 30 g of polyester-polyurethane-based liquid crystal polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 100 r / min; the pellets are then placed in a melt spinning machine for spinning, and the temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C.; the pellets are stretched by a stretching machine, the temperature of the hot plate is 80° C., the temperature of the hot plate is 170° C., and the stretching ratio is 3.4 times; and a high-strength polyester fiber containing a liquid crystal polymer is obtained.

[0036] Comparative Example 1

[0037] The difference between this comparative example and Example 1 is that the polyester-polyurethane based liquid crystal polymer is not added.

[0038] (1) 1000 g of polyethylene terephthalate is added to a twin-screw extruder for melt blending, extrusion, and pelletization. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 40 r / min; the pellets are then placed in a melt spinning machine for spinning. The temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C.; the pellets are stretched in a stretching machine. The temperature of the hot plate is 85° C., the temperature of the hot plate is 160° C., and the stretching ratio is 4 times; and polyester fibers are obtained.

[0039] Comparative Example 2

[0040] The main difference between this comparative example and Example 1 is that when preparing the polyurethane-based polymer, 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane is not added.

[0041] (1) Add 200 mL of N,N-dimethylformamide, 100 mmol of 1,6-hexanediol, 100 mmol of toluene-2,4-diisocyanate, and 0.15 g of dibutyltin dilaurate into a flask, heat to 70° C. in a nitrogen atmosphere, and react for 7 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyurethane-based polymer.

[0042] (2) 1000 g of polyethylene terephthalate and 30 g of a polyurethane-based polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 40 r / min; the pellets are then placed in a melt spinning machine for spinning, and the temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C.; the pellets are stretched by a stretching machine, the temperature of the hot plate is 85° C., the temperature of the hot plate is 160° C., and the stretching multiple is 4 times; and polyester fibers are obtained.

[0043] Comparative Example 3

[0044] The difference between this comparative example and Example 1 is that when preparing the polyurethane-based polymer, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane is used instead of 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane.

[0045] (1) Add 200 mL of N,N-dimethylformamide, 20 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 80 mmol of 1,6-hexanediol, 100 mmol of toluene-2,4-diisocyanate, and 0.15 g of dibutyltin dilaurate into a flask, heat to 70° C. in a nitrogen atmosphere, and react for 7 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyurethane-based polymer.

[0046] (2) 1000 g of polyethylene terephthalate and 30 g of a polyurethane-based polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation. The temperatures of zones 1-7 are 240° C., 255° C., 280° C., 280° C., 275° C., 275° C., and 270° C., and the screw speed is 40 r / min; the pellets are then placed in a melt spinning machine for spinning, and the temperatures of zones 1-4 are 270° C., 290° C., 300° C., and 300° C.; the pellets are stretched by a stretching machine, the temperature of the hot plate is 85° C., the temperature of the hot plate is 160° C., and the stretching multiple is 4 times; and polyester fibers are obtained.

[0047] Comparative Example 4

[0048] The difference between this comparative example and Example 1 is that when preparing the polyurethane-based polymer, biphenol is used instead of 1,3-bis(3-(biphenol propyl)-1,1,3,3-tetramethyldisiloxane.

[0049] (1) Add 200 mL of N,N-dimethylformamide, 20 mmol of biphenyl diphenol, 80 mmol of 1,6-hexanediol, 100 mmol of toluene-2,4-diisocyanate, and 0.15 g of dibutyltin dilaurate into a flask, heat to 70° C. in a nitrogen atmosphere, and react for 7 h. Add water to the solution, filter, wash with water and ethanol in turn, and dry to obtain a polyurethane-based polymer.

[0050] (2) Adding 1000g of polyethylene terephthalate and 30g of polyurethane-based polymer into a twin-screw extruder for melt blending, extrusion and granulation, the temperatures of zones 1-7 are 240°C, 255°C, 280°C, 280°C, 275°C, 275°C and 270°C, and the screw speed is 40r / min; then placing the pellets in a melt spinning machine for spinning, the temperatures of zones 1-4 are 270°C, 290°C, 300°C and 300°C; stretching by a stretching machine, the temperature of the hot plate is 85°C, the temperature of the hot plate is 160°C, and the stretching multiple is 4 times; and obtaining polyester fiber.

[0051] According to the method of GB / T 14344-2022, the tensile properties of polyester fibers were tested using an electronic yarn strength and elongation tester.

[0052] Table 1 Tensile properties test of polyester fiber

[0053] Breaking strength (cN / dtex) Elongation at break (%) Example 1 2.78 72.4 Example 2 2.85 76.9 Example 3 2.89 70.3 Comparative Example 1 2.53 62.8 Comparative Example 2 2.34 57.6 Comparative Example 3 2.41 66.7 Comparative Example 4 2.58 51.0

[0054] 5 mg of polyester fiber was weighed and placed in a thermogravimetric analyzer. The thermogravimetric performance test was performed in a nitrogen atmosphere with a heating rate of 10°C / min and a maximum test temperature of 800°C.

[0055] Table 2 Thermal performance test of polyester fiber

[0056]

[0057] Taking Example 1 as an example, the amount of polyester-polyurethane-based liquid crystal polymer used was controlled to be 70g, 110g, 150g, and 200g.

[0058] 1000g of polyethylene terephthalate and 70g-200g of polyester-polyurethane-based liquid crystal polymer are added to a twin-screw extruder for melt blending, extrusion, and granulation, with the temperatures of zones 1-7 being 240°C, 255°C, 280°C, 280°C, 275°C, 275°C, and 270°C, and the screw speed being 40r / min; then the pellets are placed in a melt spinning machine for spinning, with the temperatures of zones 1-4 being 270°C, 290°C, 300°C, and 300°C; and the fibers are stretched by a stretching machine, with the hot plate temperature being 85°C, the hot plate temperature being 160°C, and the stretching multiple being 4 times; and high-strength polyester fibers containing liquid crystal polymers are obtained.

[0059] Table 3 Test on tensile properties of polyester fibers at different polyurethane-based liquid crystal polymer dosages

[0060]

[0061] Table 4 Thermal performance test of polyester fiber at different polyurethane-based liquid crystal polymer dosages

[0062]

[0063] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a high-strength polyester fiber containing a liquid crystal polymer, characterized in that: The preparation method comprises the following steps: Step S1, adding N,N-dimethylformamide, 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane, a diol compound, a diisocyanate compound, and dibutyltin dilaurate into a flask, reacting in a nitrogen atmosphere, adding water to the solution, filtering, washing with water and ethanol in sequence, and drying to obtain a polyester-polyurethane-based liquid crystal polymer; Step S2, adding polyethylene terephthalate and polyester-polyurethane-based liquid crystal polymer into a twin-screw extruder for melt blending, extrusion, and granulation; then placing the granules in a melt spinning machine for spinning, and stretching them through a stretching machine to obtain high-strength polyester fibers containing liquid crystal polymers; The preparation method of the 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane comprises the following steps: Step 1, add toluene solvent, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 4-bromobenzoyl chloride and pyridine into a flask, heat to 35-50°C for reaction for 8-18h, rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain intermediate A; Step 2: Add 1,4-dioxane solvent, p-hydroxyphenylboronic acid, intermediate A, bis(triphenylphosphine)palladium dichloride, and potassium carbonate aqueous solution into a flask, heat to 80-100° C. in a nitrogen atmosphere, react for 24-36 hours, rotary evaporate the solution, wash with water, and recrystallize the product in ethanol to obtain 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane; In the step 1, the molar ratio of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 4-bromobenzoyl chloride and pyridine is 100:(200-210):(200-230); In the step 1, the molar ratio of p-hydroxyphenylboric acid, intermediate A, bis(triphenylphosphine)palladium dichloride and potassium carbonate is (180-220):100:(2.8-4):(340-440).

2. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 1, characterized in that: In the step S1, the reaction is carried out at 60-80° C. for 4-7 hours.

3. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 1, characterized in that: In the step S1, the molar ratio of 1,3-bis(3-(biphenyl propyl)-1,1,3,3-tetramethyldisiloxane, the diol compound and the diisocyanate compound is (20-50):(50-80):

100.

4. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 3, characterized in that: The diisocyanate compound is toluene-2,4-diisocyanate or diphenylmethane-4,4'-diisocyanate.

5. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 3, characterized in that: The structural formula of the diol compound is that n is any integer of 2-6.

6. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 1, characterized in that: The mass ratio of the polyethylene terephthalate to the polyester-polyurethane-based liquid crystal polymer is 100:(3-20).

7. The method for preparing high-strength polyester fiber containing liquid crystal polymer according to claim 1, characterized in that: The temperature of zones 1-7 of the screw extruder is 240-280°C, and the screw speed is 40-100r / min; the temperature of zones 1-4 of the melt spinning machine is 270-300°C; the hot plate temperature of the drawing machine is 80-90°C, the hot plate temperature is 160-170°C, and the drawing multiple is 3.4-4 times.

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