CN110317329B - Preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole - Google Patents
Preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole Download PDFInfo
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Abstract
The invention discloses a preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, and relates to a preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, aiming at solving the problems of non-ideal mechanical property and complex polyarylate preparation process of the existing thermotropic liquid crystal polyarylate preparation. The preparation method comprises the following steps: firstly, adding p-hydroxybenzoic acid, 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, acetic anhydride, 4-acetamidopyridine and an antioxidant into a polymerization kettle to prepare a prepolymer of thermotropic liquid crystal polyarylate through melt polycondensation; secondly, the prepolymer is placed in a rotary kiln to carry out solid-phase polycondensation reaction under the condition of nitrogen protection, so as to obtain high molecular weight polymer powder; thirdly, cooling and drafting the high molecular weight polymer powder after mixing to prepare nascent polyarylate; fourthly, carrying out heat treatment on the nascent polyarylate. The preparation method of the thermotropic liquid crystal polyarylate is simple to operate, and the stretching strength of the finally obtained polyarylate can reach 100-160 MPa.
Description
Technical Field
The invention relates to a preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole.
Background
Thermotropic Liquid Crystalline Polyarylate (TLCP) is a thermoplastic that can be extruded or injection molded using existing mechanical techniques to make fibers, films, sheets, etc., which are the next generation of engineering plastics. At present, not only universities and research institutes are widely researched worldwide, but also thirty companies are invested in research and development. The thermotropic liquid crystalline polyarylate has excellent ultraviolet ray shielding property, impact resistance, surface hardness and creep resistance. It has outstanding performance and wide application range, which are incomparable with the conventional polymer, and makes a large amount of researches on thermotropic liquid crystal polyarylate.
At present, only a few companies such as the united states and japan have mastered key production technologies for preparing liquid crystalline polyarylate high performance fibers, TLCP research and development have been carried out for many years in China, and industrialization research has been started in recent years. Domestic patent 200410054025.6 reports a solid-state preparation method of liquid crystal copolyester, specifically, a prepolymer after melt polymerization is subjected to solid-state polymerization for tens of hours to prepare high molecular weight liquid crystal polyester. But the method obviously has the problem of overlong production period and is not suitable for industrial large-scale continuous production. U.S. Pat. No. 4,169,933 describes a process for preparing polymers containing repeat units derived from hydroquinone, terephthalic acid, 2, 6-naphthalenedicarboxylic acid and 4-hydroxybenzoic acid. U.S. Pat. Nos. 5,079,289, 5,097,001 and 5,221,730 describe the preparation of polymers containing repeat units derived from the conversion of hydroquinone, terephthalic acid, isophthalic acid and 4-hydroxybenzoic acid. U.S. Pat. No. 5,492,946 relates to LCP and U.S. Pat. No. 4,851,497 relates to aromatic polyesters.
Disclosure of Invention
The invention aims to solve the problems of non-ideal mechanical property, complex preparation process and the like of the traditional preparation of thermotropic liquid crystal polyarylate, and provides a preparation method of polyarylate based on 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole.
The preparation method of the thermotropic liquid crystal polyarylate is realized by the following steps:
adding p-hydroxybenzoic acid, 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, acetic anhydride, 4-ethylaminopyridine and tin powder with the molar ratio of the polymerization monomers being (0.4-3.2): 1 into a titanium alloy polymerization kettle, keeping the temperature for 4-9 h at 125-170 ℃, then heating to 330 ℃, keeping the temperature for 2h, then filling nitrogen into the titanium alloy polymerization kettle, discharging through the titanium alloy polymerization kettle, crushing and drying to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step under the protection of nitrogen, and carrying out solid-phase polycondensation reaction in a rotary kiln at the temperature of 210-240 ℃ to obtain high-molecular-weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295-325 ℃ through a double-screw extruder, exhausting, passing through a metering pump and a component, cooling by circular air blowing, drafting, and pelletizing to obtain primary polyarylester;
and fourthly, under the protection of nitrogen, carrying out heat treatment on the nascent polyarylate to obtain the thermotropic liquid crystal polyarylate.
The preparation method of the thermotropic liquid crystal polyarylate has simple operation and easy control of reaction conditions, and the weight average molecular weight of the polymer powder prepared in the second step is 8.2 multiplied by 103～1.8×104And the molecular weight is high. The preparation process can be implemented in a polymerization kettle and a double-screw extruder, is convenient for continuous production, has the tensile strength of 50-90 MPa, and then is subjected toThe stretching strength of the thermotropic liquid crystal polyarylate finally obtained after the heat treatment can reach 100-160 MPa. The defects of complex preparation steps, difficult control of conditions, unstable quality and low finished product strength of the prior thermotropic liquid crystal polyarylate are overcome.
Detailed Description
The first embodiment is as follows: the preparation method of the thermotropic liquid crystalline polyarylate of the present embodiment is carried out by the following steps:
adding p-hydroxybenzoic acid, 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, acetic anhydride, 4-ethylaminopyridine and tin powder with the molar ratio of the polymerization monomers being (0.4-3.2): 1 into a titanium alloy polymerization kettle, keeping the temperature for 4-9 h at 125-170 ℃, then heating to 330 ℃, keeping the temperature for 2h, then filling nitrogen into the titanium alloy polymerization kettle, discharging through the titanium alloy polymerization kettle, crushing and drying to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step under the protection of nitrogen, and carrying out solid-phase polycondensation reaction in a rotary kiln at the temperature of 210-240 ℃ to obtain high-molecular-weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295-325 ℃ through a double-screw extruder, exhausting, passing through a metering pump and a component, cooling by circular blowing, drafting, and pelletizing to obtain nascent polyarylate;
and fourthly, under the protection of nitrogen, carrying out heat treatment on the nascent polyarylate to obtain the thermotropic liquid crystal polyarylate.
The prepolymer obtained in the first step of the present embodiment has an intrinsic viscosity of 1.5 to 3.5dl/g, and [ pentafluorophenol as a solvent, a 0.1mol/l solution is prepared, and the solution is measured with an Ubbelohde viscometer ], and the high molecular weight polymer powder obtained in the second step has an intrinsic viscosity of 5.5 to 10.5dl/g, and a weight average molecular weight of 8.2 × 103～1.8×104。
The preparation method of the thermotropic liquid crystal high-performance polyarylate can be realized by combining a polymerization kettle with a double-screw extruder and a device comprising a circular blowing fan, a drafting roller and a granulator, fully utilizes the advantages of the double-screw extruder such as large shearing acting force and sufficient material contact, can obviously shorten the production period while preparing the thermotropic liquid crystal polyarylate with high molecular weight, overcomes the defect of unstable product quality, and provides a simple and feasible new method for industrially and continuously producing the liquid crystal polyarylate on a large scale.
The second embodiment is as follows: this embodiment differs from the first embodiment in that the purity of the p-hydroxybenzoic acid and 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole in step one is greater than 99.4%. Other steps and parameters are the same as those in the first embodiment.
The third concrete implementation mode: the embodiment is different from the first or second embodiment in that the molar amount of acetic anhydride in the first step is 1.0 to 2.5 times of the total molar amount of the hydroxyl groups in the polymerized monomers of p-hydroxybenzoic acid and 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole. Other steps and parameters are the same as those in the first or second embodiment.
The fourth concrete implementation mode: the difference between the first embodiment and the third embodiment is that the mole number of the 4-acetamidopyridine in the first step is 0.015 to 0.040 times the total mole number of the polymerized monomers of the p-hydroxybenzoic acid and the 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridazole. Other steps and parameters are the same as those in one of the first to third embodiments.
The existing melt polycondensation reaction catalyst is one or more of zinc acetate, manganese acetate, sodium acetate, potassium acetate, cobalt acetate, lithium acetate, titanate, dibutyltin laurate, dibutyltin oxide, antimony trioxide or ethylene glycol antimony, the conversion rate is low, and a high-molecular-weight polymer cannot be formed, so that the high-performance thermotropic liquid crystal polyarylate cannot be prepared. The catalyst used in the invention does not belong to any of the catalysts, so that the conversion rate of the polycondensation reaction is improved.
The fifth concrete implementation mode: the difference between the first embodiment and the fourth embodiment is that the temperature is raised to 330 ℃ at the speed of 0.5 ℃/min, and nitrogen is filled into the titanium alloy polymerization kettle after the temperature is kept for 2 h. Other steps and parameters are the same as in one of the first to fourth embodiments.
The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is that a prepolymer is obtained by discharging through a 10-hole discharge valve having a diameter of 3mm in a titanium alloy polymerizer, pulverizing, and drying at 160 ℃. Other steps and parameters are the same as those in one of the first to fifth embodiments.
The seventh embodiment: the difference between this embodiment and the first to the sixth embodiment is that the speed of the third drawing step is 8 to 45 m/min. Other steps and parameters are the same as those in one of the first to sixth embodiments.
The specific implementation mode is eight: the present embodiment is different from the first to seventh embodiments in that the heat treatment of the nascent polyarylate is performed at 245 to 295 ℃ for 70 hours in the fourth step. Other steps and parameters are the same as those in one of the first to seventh embodiments.
The specific implementation method nine: the difference between this embodiment and the first to eighth embodiments is that the antioxidant added in the preheating stage is tin powder. Other steps and parameters are the same as those in one to eight of the embodiments.
Commonly used antioxidants in current polyesters are: the color of the polymer can be darkened by one or a combination of several of the following antioxidants 1010, 1076, 1024, 618, 626, 1024 and 1098, which are not expected to be ideal in the present invention, and which can be close to white by using tin powder.
Example (b):
adding 100g of amine aqueous solution into a 250ml three-necked bottle, cooling to 0 ℃, then adding 15g of 4-chloropyridine, heating and refluxing for 1 hour, cooling, adding 50g of toluene, extracting for 2 times, combining extract liquor, adding 10g of anhydrous magnesium sulfate, drying for 24 hours, filtering, carrying out rotary evaporation to obtain a crude product, adding the crude product into 50g of xylene, and recrystallizing to obtain 8g of near-colorless flaky crystal 4-aminopyridine for later use.
Adding 100g of polyphosphoric acid into a 250ml three-neck flask, vacuumizing to below 20mmHg, heating to 100 ℃, keeping the temperature for 3h, cooling to room temperature, adding 15g of 3, 4-diaminobenzyl alcohol and 17.7g of 4-methoxy-1, 3-isophthalic acid, heating to 90 ℃, adding 43g of phosphorus pentoxide, heating to 150 ℃ at the speed of 0.5 ℃/min, cooling to room temperature, adding into 1L of water, filtering, adding the obtained crude product into a 15% NaOH solution, refluxing for 2h, adjusting the pH to 3 with a 10% HCl aqueous solution, filtering, recrystallizing the obtained product with a 50g of DMF methanol solution (DMF: methanol: 9:1) to obtain 8g of pure 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole for later use.
The first embodiment is as follows: the preparation method of the thermotropic liquid crystalline polyarylate of the present example was carried out by the following steps:
adding 57g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 253g of acetic anhydride, 2.3g of 4-aminopyridine and 0.3g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 4 hours, heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Under the protection condition of/h, carrying out solid-phase polycondensation reaction in a rotary kiln for 50h at 210 ℃ to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3And (2) carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain the thermotropic liquid crystal polyarylate.
The intrinsic viscosity of the prepolymer prepared in step one of this example was 1.5dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in step two was 5.5dl/g, and the weight average molecular weight was 8200. The tensile strength of the nascent polyarylate obtained in the third step is 50MPa, and the tensile strength of the thermotropic liquid crystal polyarylate obtained in the fourth step can reach 100 MPa.
Example two: the preparation method of the thermotropic liquid crystalline polyarylate of the present example was carried out by the following steps:
firstly, 114g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 339g of acetic anhydride, 3.5g of 4-aminopyridine and 0.5g of tin powder are added into a titanium alloy polymerization kettle, the mixture is kept at 125 ℃ for 6 hours, then the temperature is increased to 330 ℃ at the speed of 0.5 ℃/min, 0.2MPa of nitrogen is filled into the titanium alloy polymerization kettle after the temperature is kept for 2 hours, the mixture is discharged through a 10-hole discharge valve with the diameter of 3mm, crushed, filtered by a 20-mesh sieve, and dried at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Performing solid phase polycondensation reaction in a rotary kiln for 50 hours at 210 ℃ under the condition of/h to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3And (2) carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain the thermotropic liquid crystal polyarylate.
The intrinsic viscosity of the prepolymer prepared in step one of this example was 2.1dl/g, and the intrinsic viscosity of the high molecular weight polymer powder prepared in step two was 6.3dl/g, and the weight average molecular weight was 9800. The tensile strength of the nascent polyarylate obtained in the third step is 65MPa, and the tensile strength of the thermotropic liquid crystal polyarylate obtained in the fourth step can reach 116 MPa.
Example three: the preparation method of the thermotropic liquid crystalline polyarylate of the present example was carried out by the following steps:
adding 228g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 505g of acetic anhydride, 4.7g of 4-aminopyridine and 0.8g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 8 hours, then heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, then filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Under the condition of h, carrying out solid phase polycondensation reaction for 50h in a rotary kiln at 210 ℃ to obtain high molecular weightA molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3And (2) carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain the thermotropic liquid crystal polyarylate.
The intrinsic viscosity of the prepolymer prepared in step one of this example was 3.0dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in step two was 7.8dl/g, and the weight average molecular weight was 15200. The tensile strength of the nascent polyarylate obtained in the third step is 79MPa, and the tensile strength of the thermotropic liquid crystal polyarylate obtained in the fourth step can reach 135 MPa.
Example four: the preparation method of the thermotropic liquid crystalline polyarylate of the present example was carried out by the following steps:
adding 343g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 675g of acetic anhydride, 6.2g of 4-aminopyridine and 1.1g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 9 hours, then heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, then filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Performing solid phase polycondensation reaction in a rotary kiln for 50 hours at 210 ℃ under the condition of/h to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3And (2) carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain the thermotropic liquid crystal polyarylate.
The intrinsic viscosity of the prepolymer prepared in step one of this example was 3.5dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in step two was 10.5dl/g, and the weight average molecular weight was 18000. The tensile strength of the nascent polyarylate obtained in the third step is 90MPa, and the tensile strength of the thermotropic liquid crystal polyarylate obtained in the fourth step can reach 160 MPa.
Claims (4)
1. A process for the preparation of polyarylate based on 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole, characterized in that it is carried out by the following steps:
adding 57g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 253g of acetic anhydride, 2.3g of 4-aminopyridine and 0.3g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 4 hours, heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Under the protection condition of/h, carrying out solid-phase polycondensation reaction in a rotary kiln for 50h at 210 ℃ to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3Carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain thermotropic liquid crystal polyarylate;
the intrinsic viscosity of the prepolymer prepared in the first step was 1.5dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in the second step was 5.5dl/g, and the weight average molecular weight was 8200.
2. A process for the preparation of polyarylate based on 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole, characterized in that it is carried out by the following steps:
firstly, 114g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 339g of acetic anhydride, 3.5g of 4-aminopyridine and 0.5g of tin powder are added into a titanium alloy polymerization kettle, the mixture is kept at 125 ℃ for 6 hours, then the temperature is increased to 330 ℃ at the speed of 0.5 ℃/min, 0.2MPa of nitrogen is filled into the titanium alloy polymerization kettle after the temperature is kept for 2 hours, the mixture is discharged through a 10-hole discharge valve with the diameter of 3mm, crushed, filtered by a 20-mesh sieve, and dried at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Performing solid phase polycondensation reaction in a rotary kiln for 50 hours at 210 ℃ under the condition of/h to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3Carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain thermotropic liquid crystal polyarylate;
the intrinsic viscosity of the prepolymer prepared in the first step was 2.1dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in the second step was 6.3dl/g, and the weight average molecular weight was 9800.
3. A process for the preparation of polyarylate based on 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole, characterized in that it is carried out by the following steps:
adding 228g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 505g of acetic anhydride, 4.7g of 4-aminopyridine and 0.8g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 8 hours, then heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, then filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Performing solid phase polycondensation reaction in a rotary kiln for 50 hours at 210 ℃ under the condition of/h to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3Carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain thermotropic liquid crystal polyarylate;
the intrinsic viscosity of the prepolymer prepared in the first step was 3.0dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in the second step was 7.8dl/g, and the weight average molecular weight was 15200.
4. A process for the preparation of polyarylate based on 2- (3-carboxy-4-methoxyphenyl) -5-hydroxypyridoimidazole, characterized in that it is carried out by the following steps:
adding 343g of p-hydroxybenzoic acid, 265g of 2- (3-carboxyl-4-methoxyphenyl) -5-hydroxypyridoimidazole, 675g of acetic anhydride, 6.2g of 4-aminopyridine and 1.1g of tin powder into a titanium alloy polymerization kettle, keeping the temperature at 125 ℃ for 9 hours, then heating to 330 ℃ at the speed of 0.5 ℃/min, keeping the temperature for 2 hours, then filling 0.2MPa of nitrogen into the titanium alloy polymerization kettle, discharging through a 10-hole discharging valve with the diameter of 3mm, crushing, sieving by a 20-mesh sieve, and drying at 160 ℃ for 2 hours to obtain a prepolymer;
secondly, placing the prepolymer obtained in the first step in nitrogen with the flow rate of 0.3m3Performing solid phase polycondensation reaction in a rotary kiln for 50 hours at 210 ℃ under the condition of/h to obtain high molecular weight polymer powder;
thirdly, mixing the high molecular weight polymer powder obtained in the second step at 295 ℃ through a double-screw extruder, exhausting, cooling through a metering pump and a component by circular blowing at 25 ℃, and pelletizing to obtain primary polyarylester;
fourthly, the nitrogen flow is 0.3m3Carrying out heat treatment on the nascent polyarylate for 70 hours at the temperature of 245 ℃ under the condition of/h to obtain thermotropic liquid crystal polyarylate;
the intrinsic viscosity of the prepolymer prepared in the first step was 3.5dl/g, the intrinsic viscosity of the high molecular weight polymer powder prepared in the second step was 10.5dl/g, and the weight average molecular weight was 18000.
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| CN106435807A (en) * | 2016-10-14 | 2017-02-22 | 黑龙江大学 | Method for preparing wholly-aromatic polyester fibers based on 4,4'-diaminodiphenyl ether |
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| CN106435807A (en) * | 2016-10-14 | 2017-02-22 | 黑龙江大学 | Method for preparing wholly-aromatic polyester fibers based on 4,4'-diaminodiphenyl ether |
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