CN116023638B - Fiber-grade thermotropic liquid crystal polyarylate and fiber product thereof - Google Patents
Fiber-grade thermotropic liquid crystal polyarylate and fiber product thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of organic high-performance fibers, and particularly relates to a fiber-grade thermotropic liquid crystal polyarylate and a fiber product thereof. The fiber-grade thermotropic liquid crystal polyarylester is prepared by polycondensation reaction of 55-75% of p-hydroxybenzoic acid, 20-35% of 6-hydroxy-2-naphthoic acid, 1-5% of 1,1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and 1-5% of terephthalic acid, wherein the sum of the four monomer mole percentages is 100%. The liquid crystal polyarylate prepared from specific content of monomers of parahydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and terephthalic acid has higher polymer, melting point and proper viscosity, can be used for stable spinning, and the prepared fiber has good tensile strength, modulus and elongation at break, and especially the elongation at break is improved by more than 15% compared with the indexes of the prior art.
Description
Technical Field
The invention belongs to the technical field of organic high-performance fiber production, and particularly relates to fiber-grade thermotropic liquid crystal polyarylate and a fiber product thereof.
Background
Liquid crystalline polyarylates are thermotropic liquid crystalline polymers that have evolved after the 20 th century 70 with liquid crystalline polyamides. With the advent of polyaramide-based high performance liquid crystal fiber Kelvar developed by DuPont in the United states, the development of liquid crystal polymers was greatly stimulated. However, the polymerization process of the polyaramid liquid crystal fiber needs to be carried out in an amide solvent and cannot be directly molded, so that on one hand, the control difficulty of the polymerization process is increased, and on the other hand, the solvent is difficult to completely remove, so that residues are caused, and the final performance of a product is influenced. In view of the above problems, researchers have been motivated to study thermotropic liquid crystal polymers having liquid crystallinity in a melt state without a solvent. Since the first successful development and industrialization of Thermotropic Liquid Crystalline Polyarylate (TLCPAR) under the trade name U-Polymer by Unitika, japan, 1973, efforts have been made to develop and use new varieties of liquid crystalline polyarylates.
Thermotropic liquid crystalline polyarylates have flowability, optical anisotropy between the melting point and the clearing point, and in this temperature range, molecules cannot rotate freely as a liquid due to lack of sufficient energy, and usually form nematic liquid crystals parallel to the long axis of the molecules. When the thermotropic liquid crystalline polyarylate is extruded through the spinneret orifice under high shear stress, the molecules are highly oriented, and the oriented structure is almost completely maintained during cooling and solidification due to long relaxation time, so that the thermotropic liquid crystalline polyarylate fiber having good performance can be obtained by melt spinning.
The traditional thermotropic liquid crystal polyarylate fiber generally takes a repeating unit derived from hydroxy benzoic acid and a repeating unit derived from hydroxy naphthoic acid as main chain structures, and the liquid crystal polyarylate fiber with the structural characteristics has low melting temperature and is easy to generate melt interlacing among fibers during subsequent heat treatment, so that the fiber cannot obtain ideal mechanical properties, particularly has low elongation at break, and is difficult to meet the requirement of the medical adjustable curved sheath tube on the flexibility of the fiber.
In order to solve the above problems, liquid crystal polyarylate fibers are produced by polycondensation of raw material monomers comprising hydroxybenzoic acid, hydroxynaphthoic acid, bisphenol, terephthalic acid and isophthalic acid in the invention patents CN111511968A and KR2015-0079071 to improve strength and elongation. However, the raw material monomers described in the above patent have problems of low polymerization degree and melting point, and reduced spinnability of the polyarylate resin.
Disclosure of Invention
The object of the present invention is to provide a thermotropic liquid crystalline polyarylate having good spinning property, and a fiber prepared from the thermotropic liquid crystalline polyarylate has excellent mechanical properties, particularly elongation at break, in view of the above problems in the prior art.
The aim of the invention can be achieved by the following technical scheme: a fibrous grade thermotropic liquid crystal polyarylester is prepared from 55-75% of p-hydroxybenzoic acid, 20-35% of 6-hydroxy-2-naphthoic acid, 1-5% of 1,1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and 1-5% of terephthalic acid through polycondensation reaction, wherein the sum of the four monomer mole percentages is 100%.
Preferably, the melt viscosity of the fiber grade thermotropic liquid crystalline polyarylate is 35-50pa.s.
Preferably, the melting point of the fiber-grade thermotropic liquid crystalline polyarylate is 300 ℃ or higher.
Preferably, the weight average molecular weight of the fiber-grade thermotropic liquid crystalline polyarylate is 5-8 ten thousand.
Preferably, the preparation method of the fiber-grade thermotropic liquid crystal polyarylate comprises the following steps: putting p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane, terephthalic acid, 3-methylpyrazole serving as a catalyst and acetic anhydride serving as an acetylation reagent into a hastelloy kettle, and then keeping the mixture at 130-150 ℃ for 2-8 hours; heating to 280-310 ℃ at the speed of 0.5-1.0 ℃/min, and preserving heat for 2-4h; charging nitrogen with the pressure of 0.1-1.0MPa into a polymerization kettle, discharging the prepolymer through discharging valves with the diameter of 2-4mm and the hole number of 8-10, crushing, sieving with a 20-30 mesh sieve, and drying at 120-140 ℃ for 2-3h to obtain the prepolymer; and (3) carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195-280 ℃ for 10-36h under the protection of nitrogen, so as to obtain the liquid crystal polyarylate.
Further preferably, the 3-methylpyrazole is added in an amount of 60 to 200ppm based on the total weight of the four monomers.
Further preferably, the addition amount of the acetic anhydride is 1.5 to 3.0 times of the total mole number of the hydroxyl groups of the four monomers.
A second object of the present invention is to provide a thermotropic liquid crystalline polyarylate fiber prepared from the above fiber-grade thermotropic liquid crystalline polyarylate by melt spinning.
Preferably, the thermotropic liquid crystalline polyarylate fiber is prepared by:
(1) Melting and extruding thermotropic liquid crystal polyarylate through an extruder with the temperature of 300-350 ℃, metering by a gear pump, feeding the thermotropic liquid crystal polyarylate to a spinning component, spraying out fiber filaments through the spinning component, and carrying out slow cooling circular blowing, drafting shaping, filament splitting and winding on the fiber filaments to prepare the thermotropic liquid crystal polyarylate nascent fiber;
(2) And performing heat treatment on the thermotropic liquid crystal polyarylate nascent fiber to obtain a thermotropic liquid crystal polyarylate fiber finished product.
Further preferably, the slow cooling temperature is 270-330 ℃, the circular blowing temperature is 250-310 ℃, and the drafting speed is 800-1200m/min.
Further preferably, the heat treatment includes a first heat treatment, a second heat treatment, a third heat treatment, and a fourth heat treatment in this order, where the first heat treatment is to raise the heat treatment temperature from room temperature T0 to T1, the second heat treatment is to raise the heat treatment temperature from T1 to T2, the third heat treatment is to raise the heat treatment temperature from T2 to T3, and the fourth heat treatment is to raise the heat treatment temperature from T3 to T4.
Still more preferably, T1 is less than or equal to 240 ℃ and less than or equal to 250 ℃, T2 is less than or equal to 250 ℃ and less than or equal to 260 ℃, T3 is less than or equal to 260 ℃ and less than or equal to 280 ℃, and T4 is less than or equal to 280 ℃ and less than or equal to 300.
Still further preferably, the heating rates of the respective heat treatment stages are sequentially: v1 is more than or equal to 5 ℃ and less than or equal to 10 ℃ and less than or equal to 0.2 ℃ and less than or equal to V2 is more than or equal to 0.5 ℃ and less than or equal to 1 ℃ and less than or equal to V1 is more than or equal to 5 ℃ and less than or equal to 0.1 ℃ and less than or equal to V4 is less than 0.25 ℃ and less than or equal to 0.5 ℃ and less than or equal to 1 ℃ and less than or equal to 5 ℃ and less than or equal to 1 ℃.
Compared with the prior art, the invention has the following beneficial effects:
1. the liquid crystal polyarylester prepared by adopting specific content of monomers of parahydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and terephthalic acid has higher polymerization degree, melting point and proper viscosity, has good spinning property and can be used for stable spinning.
2. The liquid crystal polyarylate fiber has good tensile strength, tensile modulus and elongation at break, and especially, the elongation at break of the fiber is improved by more than 15 percent compared with the indexes in the prior art, thereby meeting the requirements of the medical adjustable bent sheath tube on the traction wire.
Detailed Description
The invention is further illustrated by the following examples, which are not to be construed as limiting the scope of the invention. The raw materials not specifically described in the present invention are conventional raw materials, and the method not specifically described is a conventional method.
A fibrous grade thermotropic liquid crystal polyarylester is prepared from 55-75% of p-hydroxybenzoic acid, 20-35% of 6-hydroxy-2-naphthoic acid, 1-5% of 1,1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and 1-5% of terephthalic acid through polycondensation reaction, wherein the sum of the four monomer mole percentages is 100%.
For the invention, when the content of the p-hydroxybenzoic acid is lower than 55mol percent, the formed polymer is easy to solidify and adhere to the wall of the reaction kettle, and can not be smoothly discharged from the reaction kettle; when the content exceeds 75mol%, the melting point of the polymer is lowered and the heat stability is lowered. The content of parahydroxybenzoic acid should be controlled within the range of 55-75% from the viewpoint of melting point and polymerization.
For the present invention, when the content of 6-hydroxy-2-naphthoic acid is less than 20mol%, the melting point of the polymer is lowered and the heat stability is lowered; when the content exceeds 35mol%, the polymer is easily coagulated and adhered to the wall of the reaction kettle, and cannot be smoothly discharged out of the reaction kettle. The content of 6-hydroxy-2-naphthoic acid should be controlled within a range of 20 to 35% from the viewpoint of melting point and polymerization.
For the invention, the 1,1' -bis (4-hydroxy-3-methylphenyl) cyclohexane has a flexible group, and after the polymerization, the rigid linear structure of the liquid crystal polyarylate can be broken, so that the liquid crystal polyarylate is endowed with certain flexibility. When the content is lower than 1%, the rigidity structure of the whole molecular chain is limited to change, and the elongation at break change of the prepared fiber is not obvious; when the content exceeds 5%, the molecular chain is reduced in strength due to the introduction of an excessive amount of a flexible group.
In the present invention, when the terephthalic acid content is less than 1mol%, the polymer formed is easily coagulated and adhered to the reactor wall, and cannot be smoothly discharged from the reactor, and when the terephthalic acid content exceeds 5%, the liquid crystal polyarylate becomes low in melting point.
Preferably, the melt viscosity of the fiber grade thermotropic liquid crystalline polyarylate is 35-50pa.s. For this spinning-grade liquid crystal polyarylate, the viscosity is lower than 35, it is difficult to obtain strength satisfying the requirement and the fiber is liable to break, whereas it is higher than 50, the requirement for equipment is relatively high, special equipment needs to be added to match with it, and the manufacturing cost is increased.
Preferably, the melting point of the fiber-grade thermotropic liquid crystalline polyarylate is 300 ℃ or higher.
Preferably, the weight average molecular weight of the fiber-grade thermotropic liquid crystalline polyarylate is 5-8 ten thousand. The molecular weight of the liquid crystal polyarylester is more than 5 ten thousand, and the liquid crystal polyarylester has proper viscosity at the spinning temperature, thereby being convenient for spinning. As the molecular weight increases, the strength and modulus of the fiber increase, but the molecular weight is too high, the melt viscosity increases, the fluidity becomes poor, even no longer has fluidity,
spinning cannot be performed, and therefore, the molecular weight is preferably not more than 8 ten thousand.
Preferably, the preparation method of the fiber-grade thermotropic liquid crystal polyarylate comprises the following steps: putting p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane, terephthalic acid, 3-methylpyrazole serving as a catalyst and acetic anhydride serving as an acetylation reagent into a hastelloy kettle, and then keeping the mixture at 130-150 ℃ for 2-8 hours; heating to 280-310 ℃ at the speed of 0.5-1.0 ℃/min, and preserving heat for 2-4h; charging nitrogen with the pressure of 0.1-1.0MPa into a polymerization kettle, discharging the prepolymer through discharging valves with the diameter of 2-4mm and the hole number of 8-10, crushing, sieving with a 20-30 mesh sieve, and drying at 120-140 ℃ for 2-3h to obtain the prepolymer; and (3) carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195-280 ℃ for 10-36h under the protection of nitrogen, so as to obtain the liquid crystal polyarylate.
Further preferably, the 3-methylpyrazole is added in an amount of 60 to 200ppm based on the total weight of the four monomers. Compared with the traditional catalyst, the invention takes 3-methylpyrazole as the catalyst to participate in the polymerization reaction, and has better catalytic efficiency and fewer side reactions.
Further preferably, the addition amount of the acetic anhydride is 1.5 to 3.0 times of the total mole number of the hydroxyl groups of the four monomers. When the amount of acetic anhydride added is less than 1.5, the polymerization degree is low, the viscosity of the resulting polymer is low, and the fiber is broken during spinning, and carbonization occurs at a high spinning temperature, so that it is difficult to carry out fiberization; when the addition amount thereof exceeds 3.0, excessive acetic anhydride remains on the surface of the polymer resin and generates gas, resulting in easy filament breakage of the fiber upon spinning.
Example 1
Parahydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane, terephthalic acid and 3-methylpyrazole in an amount of 60ppm based on the total weight of the four monomers, and acetic anhydride in an amount of 1.5 times the total mole number of the hydroxyl groups of the four monomers were charged into a hastelloy kettle according to the monomer ratios corresponding to example 1 in Table 1, and then kept at 130℃for 8 hours; heating to 280 ℃ at the speed of 0.5 ℃/min, and preserving heat for 4 hours; charging nitrogen with the pressure of 0.1MPa into a polymerization kettle, discharging the prepolymer through discharge valves with the diameter of 2mm and the hole number of 8, crushing, sieving with a 20-mesh sieve, and drying at 120 ℃ for 3 hours to obtain the prepolymer; and (3) carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at the temperature of 195 ℃ for 36 hours under the protection of nitrogen, so as to obtain the liquid crystal polyarylate.
Example 2
Parahydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane, terephthalic acid and 3-methylpyrazole in an amount of 100ppm based on the total weight of the four monomers, and acetic anhydride in an amount of 2.0 times the total mole number of the hydroxyl groups of the four monomers were charged into a hastelloy kettle according to the monomer ratios corresponding to example 2 in table 1, and then kept at 140 ℃ for 4 hours; heating to 300 ℃ at the speed of 0.8 ℃/min, and preserving heat for 3 hours; charging nitrogen with the pressure of 0.5MPa into a polymerization kettle, discharging the prepolymer through discharge valves with the diameter of 3mm and the hole number of 9, crushing, sieving with a 20-mesh sieve, and drying at 130 ℃ for 2 hours to obtain the prepolymer; and (3) carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 260 ℃ for 16 hours under the protection of nitrogen, so as to obtain the liquid crystal polyarylate.
Examples 3 to 4
The polymerization was carried out in accordance with the monomer ratios corresponding to examples 3-4 in Table 1. Otherwise, the same as in example 2 was conducted.
Example 5
Adding four monomers with the same adding proportion as that of the embodiment 2, wherein the adding proportion is 160ppm of 3-methylpyrazole accounting for the total weight of the four monomers, and acetic anhydride accounting for 2.8 times of the total mole number of hydroxyl groups of the four monomers into a hastelloy kettle, and then keeping the mixture at 145 ℃ for 6 hours; heating to 305 ℃ at the speed of 0.9 ℃/min, and preserving heat for 3 hours; charging nitrogen with the pressure of 0.7MPa into a polymerization kettle, discharging the prepolymer through discharge valves with the diameter of 4mm and the hole number of 8, crushing, sieving with a 20-30 mesh sieve, and drying at 135 ℃ for 2 hours to obtain the prepolymer; and (3) solid-phase polycondensing the prepared prepolymer in a rotary kiln at 270 ℃ for 24 hours under the protection of nitrogen to obtain the liquid crystal polyarylate.
Example 6
Adding four monomers with the same adding proportion as that of the embodiment 2, wherein the 3-methylpyrazole accounts for 200ppm of the total weight of the four monomers, and the acetic anhydride accounts for 3.0 times of the total mole number of hydroxyl groups of the four monomers into a hastelloy kettle, and then keeping the mixture at 150 ℃ for 2 hours; heating to 310 ℃ at a speed of 1.0 ℃/min, and preserving heat for 2 hours; 1.0MPa nitrogen is flushed into a polymerization kettle, the prepolymer is discharged through a discharging valve with the diameter of 4mm and the hole number of 10, crushed, sieved by a 30-mesh sieve, and dried for 2 hours at 140 ℃ to prepare the prepolymer; and (3) carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 280 ℃ for 10 hours under the protection of nitrogen, so as to obtain the liquid crystal polyarylate.
Comparative example 1
Polymerization was carried out using the monomer ratios corresponding to comparative example 1 in Table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 2
Polymerization was carried out using the monomer ratios corresponding to comparative example 2 in table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 3
Polymerization was carried out using the monomer ratios corresponding to comparative example 3 in Table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 4
Polymerization was carried out using the monomer ratios corresponding to comparative example 4 in Table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 5
Polymerization was carried out using the monomer ratios corresponding to comparative example 5 in Table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 6
Polymerization was carried out using the monomer ratios corresponding to comparative example 6 in Table 1. Otherwise, the same as in example 2 was conducted.
Comparative example 7
The difference from example 2 was only that the amount of acetic anhydride added during the polymerization reaction was 1.0. Otherwise, the same as in example 2 was conducted.
Comparative example 8
The difference from example 2 was only that the amount of acetic anhydride added during the polymerization was 3.5. Otherwise, the same as in example 2 was conducted.
Comparative example 9
The only difference from example 2 is that potassium acetate was used as catalyst during the polymerization. Otherwise, the same as in example 2 was conducted.
The thermotropic liquid crystalline polyarylates of examples 1 to 6 and comparative examples 1 to 9 were evaluated for melting point, melt viscosity, and weight average molecular weight according to the following methods, and the evaluation results are shown in Table 1.
(1) Melting point: melting point testing was performed using a differential scanning calorimeter/DSC-500C in accordance with ISO11357-1/-3 standard.
(2) Melt viscosity: heating the liquid crystalline polymer to 25+ -5deg.C above the melting point for 1000s -1 Melt viscosity was measured at shear rate using a rheometer according to GB/T25278-2010.
(3) Weight average molecular weight: using pentafluorophenol/chloroform with the weight ratio of 35/65 as a mixed solvent, dissolving the liquid crystal polymer in the mixed solvent to form a solution with the concentration of 0.03-0.06 weight/volume percent, extracting supernatant after the dissolution is finished, measuring by using a gel permeation chromatography analysis instrument, and converting by using polystyrene to obtain the weight average molecular weight of the liquid crystal polymer.
TABLE 1
What needs to be specifically stated is: in comparative example 6, severe coagulation occurred during polymerization, and the reaction vessel was not smoothly discharged.
The liquid crystalline polyarylates prepared in examples 1 to 6 above were used for fiber production.
Application examples 1 to 6
The liquid crystal polyarylate in the examples 1-6 is melted and extruded by an extruder with the temperature of 320 ℃, measured by a gear pump and supplied to a spinning component, fiber filaments are sprayed out by the spinning component, the fiber filaments are slowly cooled at 300 ℃ and circularly blown at 280 ℃, and are subjected to drafting shaping, filament splitting and winding at the drafting rate of 1000m/min, so that the liquid crystal polyarylate nascent fiber is prepared;
the as-spun fibers were placed in a heat treatment furnace to perform the following heat treatments: heating from room temperature to 245 ℃ at a heating rate of 8 ℃/min, and keeping for 30min; then heating to 255 ℃ at a heating rate of 0.4 ℃/min; then heating to 270 ℃ at a heating rate of 3 ℃/min; then the temperature is raised to 290 ℃ at the heating rate of 0.2 ℃/min, and the temperature is kept for 40min.
Application example 7
The liquid crystal polyarylate prepared in the example 2 is melted and extruded by an extruder with the temperature of 300 ℃, measured by a gear pump and supplied to a spinning component, fiber filaments are sprayed out by the spinning component, subjected to slow cooling at 270 ℃ and circular blowing at 250 ℃, subjected to drafting shaping at the drafting rate of 800m/min, and subjected to filament splitting and winding, so that the liquid crystal polyarylate nascent fiber is prepared;
the as-spun fibers were placed in a heat treatment furnace to perform the following heat treatments: heating from room temperature to 240 ℃ at a heating rate of 5 ℃/min, and keeping for 30min; then heating to 250 ℃ at a heating rate of 0.2 ℃/min; then heating to 260 ℃ at a heating rate of 1 ℃/min; then the temperature is raised to 280 ℃ at the heating rate of 0.1 ℃/min, and the temperature is kept for 30min.
Application example 8
The liquid crystal polyarylate prepared in the example 2 is melted and extruded by an extruder with the temperature of 350 ℃, measured by a gear pump and supplied to a spinning component, fiber filaments are sprayed out by the spinning component, slow cooling at 330 ℃ and circular blowing at 310 ℃ are carried out on the fiber filaments, and drafting shaping, filament splitting and winding are carried out at the drafting rate of 1200m/min, so that the liquid crystal polyarylate nascent fiber is prepared;
the as-spun fibers were placed in a heat treatment furnace to perform the following heat treatments: heating from room temperature to 250 ℃ at a heating rate of 10 ℃/min, and keeping for 30min; then heating to 260 ℃ at a heating rate of 0.5 ℃/min; then heating to 280 ℃ at a heating rate of 5 ℃/min; then the temperature is raised to 300 ℃ at the heating rate of 0.25 ℃/min, and the temperature is kept for 60min.
Comparative application examples 1 to 9
The liquid crystalline polyarylates of comparative examples 1 to 9 were prepared into fibers according to the process methods of application examples 1 to 6.
Comparative application example 10
The difference from application example 2 was only that the fiber was subjected to heat treatment once after being placed in a heat treatment furnace, i.e., directly heated from room temperature to 290 ℃ at a heating rate of 5 ℃/min.
The thermotropic liquid crystalline polyarylate fibers of application examples 1 to 8 and comparative application examples 1 to 10 were subjected to test evaluation of tensile strength, tensile modulus, elongation at break, and spinnability according to the following methods, and the evaluation results are shown in Table 2.
(1) The tensile strength, tensile modulus and elongation at break are respectively tested according to the GB/T19975-2005 method under the conditions of 20+/-2 ℃ and 60+/-3% of humidity
(2) During the fiber winding process, the spinning property is observed to see whether the fiber has broken filaments, and the definition is usually carried out according to the following standard:
o: the yarn is not broken when coiling at normal speed;
delta: the yarn is not broken when the winding speed is reduced;
x: the yarn breaks even if the winding speed is reduced.
TABLE 2
As can be seen from the test results in tables 1 and 2, the thermotropic liquid crystal polyarylate prepared by adopting the technical scheme of the invention has higher polymer, melting point and proper viscosity, can be stably used for fiber spinning, and the manufactured fiber has excellent elongation at break, and compared with the prior art, the elongation at break is improved by more than 15%, thereby completely meeting the requirement of traction wires in an adjustable bending sheath tube on the flexibility of the fiber, and simultaneously maintaining higher strength and modulus.
In particular, polyarylene sulfide (PAS), polyphenylene ether (PPE), polycarbonate (PC), polyethylene (PE), polyacetal (POM), polyamide (PA) may be added to the liquid crystal polyarylate within a range that does not impair the effects of the present invention; organic additives such as polybutylene terephthalate (PBT) and modified polyethylene terephthalate (PET); inorganic additives such as mica, talc, kaolin, silica, etc. may also be added.
In the foregoing, various corresponding changes and modifications may be made by those skilled in the art according to the technical scheme and technical conception of the present invention, and any minor modifications, equivalent changes and modifications to the above embodiments may be made according to the technical spirit or raw material components or contents of the present invention, which fall within the scope of the technical scheme of the present invention.
Claims (5)
1. A fiber-grade thermotropic liquid crystal polyarylate is characterized in that the fiber-grade thermotropic liquid crystal polyarylate is prepared by polycondensation reaction of 55-75% of p-hydroxybenzoic acid, 20-35% of 6-hydroxy-2-naphthoic acid, 1-5% of 1,1' -bis (4-hydroxy-3-methylphenyl) cyclohexane and 1-5% of terephthalic acid, wherein the sum of the four monomer mole percentages is 100%; the fiber-grade thermotropic liquid crystal polyarylate is prepared by the following method: putting p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 1' -bis (4-hydroxy-3-methylphenyl) cyclohexane, terephthalic acid, 3-methylpyrazole serving as a catalyst and acetic anhydride serving as an acetylation reagent into a hastelloy kettle, and then keeping the mixture at 130-150 ℃ for 2-8 hours; heating to 280-310 ℃ at the speed of 0.5-1.0 ℃/min, and preserving heat for 2-4h; charging nitrogen with the pressure of 0.1-1.0MPa into a polymerization kettle, discharging the prepolymer through discharging valves with the diameter of 2-4mm and the hole number of 8-10, crushing, sieving with a 20-30 mesh sieve, and drying at 120-140 ℃ for 2-3h to obtain the prepolymer; solid phase polycondensation is carried out on the prepared prepolymer in a rotary kiln at 195-280 ℃ for 10-36 hours under the protection of nitrogen, thus preparing liquid crystal polyarylate; the addition amount of the 3-methylpyrazole is 60-200ppm of the total weight of the four monomers; the addition amount of the acetic anhydride is 1.5-3.0 times of the total mole number of the four monomer hydroxyl groups.
2. The fiber grade thermotropic liquid crystalline polyarylate according to claim 1, wherein said thermotropic liquid crystalline polyarylate has a melting point of 300 ℃ or higher.
3. The fiber grade thermotropic liquid crystalline polyarylate according to claim 1, wherein said thermotropic liquid crystalline polyarylate has a melt viscosity of 35 to 50pa.s.
4. A thermotropic liquid crystalline polyarylate fiber, wherein the thermotropic liquid crystalline polyarylate fiber is prepared by:
(1) Melt-extruding the thermotropic liquid crystal polyarylate according to any one of claims 1-3 by an extruder with the temperature of 300-350 ℃, metering by a gear pump, feeding the melt-extruded thermotropic liquid crystal polyarylate to a spinning component, spraying out fiber filaments by the spinning component, and carrying out slow cooling circular blowing, drafting shaping, filament splitting winding on the fiber filaments to prepare the liquid crystal polyarylate nascent fiber;
(2) Carrying out heat treatment on the liquid crystal polyarylate nascent fiber to obtain a liquid crystal polyarylate fiber finished product; the heat treatment specifically comprises the following steps: the heat treatment sequentially comprises a first heat treatment, a second heat treatment, a third heat treatment and a fourth heat treatment, wherein the first heat treatment is to raise the heat treatment temperature from room temperature T0 to T1, the second heat treatment is to raise the heat treatment temperature from T1 to T2, the third heat treatment is to raise the heat treatment temperature from T2 to T3, the fourth heat treatment is to raise the heat treatment temperature from T3 to T4, wherein T1 is more than or equal to 240 ℃ and less than or equal to 250 ℃, T2 is more than or equal to 250 ℃ and less than or equal to 260 ℃, T3 is more than or equal to 260 ℃ and less than or equal to 280 ℃, and T4 is more than or equal to 280 ℃.
5. The thermotropic liquid crystalline polyarylate fiber according to claim 4, wherein the slow cooling temperature is 270 to 330 ℃, the ring blowing temperature is 250 to 310 ℃, and the drawing speed is 800 to 1200m/min.
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| CN116903838B (en) * | 2023-09-13 | 2024-01-30 | 宁波聚嘉新材料科技有限公司 | Liquid crystal polymer, fiber and preparation method thereof, fiber cloth and copper-clad plate |
| CN117510814B (en) * | 2024-01-04 | 2024-03-29 | 宁波聚嘉新材料科技有限公司 | Liquid crystal polymer, fiber, preparation method of liquid crystal polymer and fiber, and conductive fiber |
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