阅读说明：本技术 一种高冲击强度液晶聚芳酯及其制备方法和应用 (High-impact-strength liquid crystal polyarylate and preparation method and application thereof ) 是由 王阳 任忠平 阮艳超 于 2021-09-30 设计创作，主要内容包括：本发明属于高分子聚合物技术领域,具体涉及一种高冲击强度液晶聚芳酯及其制备方法和应用。本发明的液晶聚芳酯由以下单体制成：对羟基苯甲酸、对苯二酚、联苯二甲酸、4-(4-羧基-3-氟苯基)-2-氟苯甲酸。制备步骤为预聚、固相缩聚。本发明通过引入新型单体4-(4-羧基-3-氟苯基)-2-氟苯甲酸与对羟基苯甲酸、对苯二酚、联苯二甲酸共聚,可显著提高液晶聚芳酯的冲击强度,冲击强度可达170J/m以上,同时还能获得较佳的熔体张力,熔体张力可达61mN以上,能够满足如电子薄壁制件对耐冲击性能的要求,还能实现稳定制膜。(The invention belongs to the technical field of high molecular polymers, and particularly relates to high-impact-strength liquid crystal polyarylate as well as a preparation method and application thereof. The liquid crystalline polyarylate of the present invention is prepared from the following monomers: p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid. The preparation steps are prepolymerization and solid phase polycondensation. According to the invention, by introducing the novel monomer 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, the p-hydroxybenzoic acid, the hydroquinone and the biphenyldicarboxylic acid for copolymerization, the impact strength of the liquid crystal polyarylate can be obviously improved, the impact strength can reach more than 170J/m, better melt tension can be obtained, the melt tension can reach more than 61mN, the requirements of electronic thin-wall parts on the impact resistance can be met, and stable film preparation can be realized.)

1. A high impact strength liquid crystalline polyarylate, wherein said liquid crystalline polyarylate is prepared from the following monomers:

p-hydroxybenzoic acid, having the formula:

hydroquinone, the structural formula of which is:

biphenyldicarboxylic acid having the formula:

4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid having the formula:

the molar percentages of the above monomers are respectively represented by A, B, C, D in mol%, and the correlation is as follows: 63 ≦ A ≦ 80, 20 ≦ B + C + D ≦ 37; b ═ C + D; 1.2 ≦ D ≦ 3.0; a + B + C + D is 100.

2. A method for preparing a high impact strength liquid crystalline polyarylate as claimed in claim 1, wherein said method comprises the steps of:

s1: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetylation reagent acetic anhydride, a catalyst of 2-methylaminobenzothiazole and an antioxidant stannous chloride into a Hastelloy polymerization kettle for prepolymerization to prepare a prepolymer;

s2: discharging the prepolymer from the Hastelloy kettle, crushing, and performing solid phase polycondensation in a nitrogen atmosphere to obtain the liquid crystal polyarylate.

3. The method of claim 2, wherein the amount of acetic anhydride added is 1.5 to 2.5 times the total number of moles of hydroxyl groups in the hydroxyl group-containing monomer.

4. The method of preparing a high impact strength liquid crystalline polyarylate of claim 2 wherein said 2-methylaminobenzothiazole is added in an amount of 60 to 300ppm based on the total weight of the four monomers.

5. The method of preparing a high impact strength liquid crystalline polyarylate as claimed in claim 2, wherein the stannous chloride is added in an amount of 0.14 to 0.30% by weight based on the total weight of the four monomers.

6. The method for preparing a high impact strength liquid crystalline polyarylate as claimed in claim 2, wherein the step S1 is specifically: putting the raw materials into a Hastelloy polymerization kettle, and keeping the temperature at 135-150 ℃ for 3-8 h; heating to 320 ℃ at the speed of 0.5-1.0 ℃/min, and preserving the heat for 1-3 h; charging 0.4-0.9MPa nitrogen into the polymerization kettle, discharging the prepolymer through a discharge valve with 8-10 holes with the diameter of 2-4mm, crushing, sieving with a 20-30 mesh sieve, and drying at the temperature of 160 ℃ for 1-3h to obtain the prepolymer.

7. The method for preparing a high impact strength liquid crystalline polyarylate as claimed in claim 2, wherein the step S2 is specifically: and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195-320 ℃ under the protection of nitrogen for 12-48h to prepare the liquid crystal polyarylate.

8. Use of the high impact strength liquid crystalline polyarylate as claimed in claim 1 for the preparation of a film.

9. Use of the high impact strength liquid crystalline polyarylate in the preparation film according to claim 8, wherein the liquid crystalline polyarylate film is prepared by a blow molding method; the liquid crystal polyarylate film is prepared by putting liquid crystal polyarylate in a screw extruder for melting plasticization, extruding the liquid crystal resin in a molten state into a cylindrical tube blank through an annular die head, simultaneously injecting compressed air into the tube blank to further blow up the tube blank, and cooling, drawing and rolling the tube blank.

10. The use of a high impact strength liquid crystalline polyarylate in the preparation of a film according to claim 8 wherein the liquid crystalline polyarylate film is prepared by a T-molding method; the method specifically comprises the steps of putting liquid crystal polyarylate into a screw extruder for melting and plasticizing, then extruding through a T die head, casting onto a cooling roller, cooling and shaping, and further carrying out uniaxial or biaxial stretching, edge cutting and rolling to obtain the liquid crystal polyarylate film.

Technical Field

The invention belongs to the technical field of high polymer polymerization, and particularly relates to high-impact-strength liquid crystal polyarylate as well as a preparation method and application thereof.

Background

As communication speeds become faster and faster, 5G communication is moving to the world. Since this new technology is applied to the high frequency range, the requirements of low dielectric constant and dielectric loss, good mechanical properties, and low moisture absorption are put on the material of the device. LCP is recognized as the preferred material for 5G communication due to its excellent dielectric properties, low hygroscopicity, dimensional stability, etc.

Despite the above-mentioned excellent properties, LCP's are still required to have further improved impact strength when used in certain devices (e.g., electronic thin-walled molded parts), and certain melt tensions (above 25 mN) are required for film processing. The prior art CN109796730A reports that a wholly aromatic liquid crystal polyester resin is used as a base resin component, and the wholly aromatic liquid crystal polyester resin is modified by a reactive ethylene copolymer to improve the impact strength of a liquid crystal polyester resin compound; in addition, CN1760232B reports that the whiteness and impact performance of the obtained product can be improved by adding dihydric phosphate in the synthesis process of thermotropic liquid crystal polyester; CN109824876B reports that the use of different temperature rise rates at different stages of the polymerization reaction can result in a small amount of branching of the TLCP polyarylate chain, and the resulting TLCP resin exhibits a higher melt tension. The technology only aims at the single performance of impact resistance or melt tension, and the research of combining the two performances is not reported yet. The inventors have essentially improved the impact resistance and melt tension of LCP's by introducing novel monomers for chemical copolymerization and have achieved significant results.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a high-impact-strength liquid crystal polyarylate, wherein the specific proportion of the monomer 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, p-hydroxybenzoic acid, hydroquinone and biphenyldicarboxylic acid is introduced into the liquid crystal polyarylate for copolymerization, so that the impact resistance of the liquid crystal polyarylate can be greatly improved, the obtained liquid crystal polyarylate has better melt tension, and the requirement of stable film preparation can be met.

A high impact strength liquid crystalline polyarylate prepared from the following monomers:

p-hydroxybenzoic acid, having the formula:

hydroquinone, the structural formula of which is:

biphenyldicarboxylic acid having the formula:

4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid having the formula:

the molar percentages of the above monomers are respectively represented by A, B, C, D in mol%, and the correlation is as follows: 63 ≦ A ≦ 80; 20 ≦ B + C + D ≦ 37; b ═ C + D; 1.2 ≦ D ≦ 3.0; a + B + C + D is 100.

The second object of the present invention is to provide a method for preparing the above liquid crystalline polyarylate, which comprises the steps of:

s1: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetylation reagent acetic anhydride, a catalyst of 2-methylaminobenzothiazole and an antioxidant stannous chloride into a Hastelloy polymerization kettle for prepolymerization to prepare a prepolymer;

s2: discharging the prepolymer from the Hastelloy kettle, crushing, and performing solid phase polycondensation in a nitrogen atmosphere to obtain the liquid crystal polyarylate.

Preferably, the amount of the acetic anhydride added is 1.5 to 2.5 times the total number of moles of hydroxyl groups in the hydroxyl group-containing monomer.

Preferably, the 2-methylaminobenzothiazole is added in an amount of 60 to 300ppm based on the total weight of the four monomers.

Preferably, the addition amount of the stannous chloride is 0.14-0.30% of the total weight of the four monomers.

Preferably, the step S1 is specifically: putting the raw materials into a Hastelloy polymerization kettle, and keeping the temperature at 135-150 ℃ for 3-8 h; heating to 320 ℃ at the speed of 0.5-1.0 ℃/min, and keeping the temperature for 1-3 h; charging 0.4-0.9MPa nitrogen into the polymerization kettle, discharging the prepolymer through a discharge valve with 8-10 holes with the diameter of 2-4mm, crushing, sieving with a 20-30 mesh sieve, and drying at the temperature of 160 ℃ for 1-3h to obtain the prepolymer.

Preferably, the step S2 is specifically: and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195-320 ℃ under the protection of nitrogen for 12-48h to prepare the liquid crystal polyarylate.

It is still another object of the present invention to provide a use of the above liquid crystalline polyarylate for preparing a film.

The liquid crystalline polyarylate film of the present invention can be prepared by the following method:

(1) blow molding process

And (2) putting the liquid crystal polyarylate into a screw extruder for melting plasticization, then extruding the molten liquid crystal resin into a cylindrical pipe blank through an annular die head, simultaneously injecting compressed air into the pipe blank to further blow up the pipe blank, and cooling, drawing and rolling to obtain the liquid crystal polyarylate film.

(2) T-die method

And (2) putting the liquid crystal polyarylate into a screw extruder for melting and plasticizing, then extruding through a T die head, casting onto a cooling roller, cooling and shaping, and further carrying out uniaxial or biaxial stretching, edge cutting and rolling to obtain the liquid crystal polyarylate film.

Compared with the prior art, the invention has the following beneficial effects:

under the synergistic action of a catalyst 2-methylaminobenzothiazole and an antioxidant stannous chloride, by introducing a novel monomer 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, p-hydroxybenzoic acid, hydroquinone and biphenyldicarboxylic acid for copolymerization, the impact strength of liquid crystal polyarylate (more than 170J/m) is improved, and simultaneously, better melt tension (more than 61 mN) can be obtained, so that the requirements of electronic thin-wall parts on the impact resistance can be met, and stable film preparation can be realized.

Detailed Description

The following are specific examples of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these examples. In the present invention, unless otherwise specified, the starting materials or reagents used are those conventionally used, and the methods used are those conventionally used.

A high impact strength liquid crystalline polyarylate prepared from the following monomers:

p-hydroxybenzoic acid, having the formula:

hydroquinone, the structural formula of which is:

biphenyldicarboxylic acid having the formula:

4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid having the formula:

the molar percentages of the above monomers are respectively represented by A, B, C, D in mol%, and the correlation is as follows: 63 ≦ A ≦ 80, 20 ≦ B + C + D ≦ 37; b ═ C + D; 1.2 ≦ D ≦ 3.0; a + B + C + D is 100.

The preparation method of the high impact strength liquid crystal polyarylate comprises the following steps:

s1: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetylation reagent acetic anhydride, a catalyst of 2-methylaminobenzothiazole and an antioxidant stannous chloride into a Hastelloy polymerization kettle for prepolymerization to prepare a prepolymer;

s2: discharging the prepolymer from the Hastelloy kettle, crushing, and performing solid phase polycondensation in a nitrogen atmosphere to obtain the liquid crystal polyarylate.

In the above production method, the amount of acetic anhydride added is preferably 1.5 to 2.5 times the total number of moles of hydroxyl groups in the hydroxyl group-containing monomer.

In the above preparation method, the preferred amount of 2-methylaminobenzothiazole to be added is 60 to 300ppm based on the total weight of the four monomers.

In the above preparation method, the amount of stannous chloride added is preferably 0.14 to 0.30% of the total weight of the four monomers.

In the above preparation method, the preferable step S1 is specifically: putting the raw materials into a Hastelloy polymerization kettle, and keeping the temperature at 135-150 ℃ for 3-8 h; heating to 320 ℃ at the speed of 0.5-1.0 ℃/min, and preserving the heat for 1-3 h; charging 0.4-0.9MPa nitrogen into the polymerization kettle, discharging the prepolymer through a discharge valve with 8-10 holes with the diameter of 2-4mm, crushing, sieving with a 20-30 mesh sieve, and drying at the temperature of 160 ℃ for 1-3h to obtain the prepolymer.

In the above preparation method, the preferable step S2 is specifically: and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195-320 ℃ under the protection of nitrogen for 12-48h to prepare the liquid crystal polyarylate.

The embodiments of the present invention will be described in detail by the following examples and comparative examples. The monomer formulations of examples 1-4 of the invention are shown in Table 1:

table 1: monomer ratios in examples 1-4

Example 5

The preparation of liquid crystalline polyarylate was carried out according to the monomer formulation in example 1, with the following specific procedure: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetic anhydride accounting for 1.5 times of the total mole number of hydroxyl in the hydroxyl-containing monomers, 2-methylamino benzothiazole accounting for 60ppm of the total weight of the four monomers and stannous chloride accounting for 0.14 percent of the total weight of the four monomers into a Hastelloy polymerization kettle, and keeping the mixture at 135 ℃ for 3 hours; heating to 300 ℃ at the speed of 0.5 ℃/min, and keeping the temperature for 1 h; flushing 0.4MPa nitrogen into a polymerization kettle, discharging the prepolymer through an 8-hole discharge valve with the diameter of 2mm, crushing, sieving with a 20-mesh sieve, and drying at 145 ℃ for 1h to obtain the prepolymer; and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 195 ℃ for 12h under the protection of nitrogen to prepare the liquid crystal polyarylate.

Example 6

The preparation of liquid crystalline polyarylate was carried out according to the monomer formulation in example 2, the specific procedure was: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetic anhydride accounting for 1.8 times of the total mole number of hydroxyl in the hydroxyl-containing monomers, 2-methylamino benzothiazole accounting for 130ppm of the total weight of the four monomers and stannous chloride accounting for 0.20 percent of the total weight of the four monomers into a Hastelloy polymerization kettle, and keeping the mixture at 140 ℃ for 5 hours; heating to 305 ℃ at the speed of 0.6 ℃/min, and keeping the temperature for 2 h; flushing 0.6MPa nitrogen into a polymerization kettle, discharging the prepolymer through an 8-hole discharge valve with the diameter of 2mm, crushing, sieving with a 25-mesh sieve, and drying at 150 ℃ for 2 hours to obtain the prepolymer; and carrying out solid-phase polycondensation on the prepared prepolymer in a rotary kiln at 240 ℃ for 16h under the protection of nitrogen to prepare the liquid crystal polyarylate.

Example 7

The preparation of liquid crystalline polyarylate was carried out according to the monomer formulation in example 3, the specific procedure was: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetic anhydride accounting for 2.0 times of the total mole number of hydroxyl in the hydroxyl-containing monomers, 2-methylamino benzothiazole accounting for 210ppm of the total weight of the four monomers and stannous chloride accounting for 0.24 percent of the total weight of the four monomers into a Hastelloy polymerization kettle, and keeping the mixture at 145 ℃ for 6 hours; heating to 310 ℃ at the speed of 0.8 ℃/min, and keeping the temperature for 2 h; flushing 0.7MPa nitrogen into a polymerization kettle, discharging the prepolymer through a 9-hole discharge valve with the diameter of 3mm, crushing, sieving with a 25-mesh sieve, and drying at 155 ℃ for 3 hours to obtain the prepolymer; and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 280 ℃ for 24 hours under the protection of nitrogen to prepare the liquid crystal polyarylate.

Example 8

The preparation of liquid crystalline polyarylate was carried out according to the monomer formulation in example 4, with the specific procedure: putting monomers of p-hydroxybenzoic acid, hydroquinone, diphenic acid, 4- (4-carboxyl-3-fluorophenyl) -2-fluorobenzoic acid, acetic anhydride accounting for 2.5 times of the total mole number of hydroxyl in the hydroxyl-containing monomers, 2-methylamino benzothiazole accounting for 300ppm of the total weight of the four monomers and stannous chloride accounting for 0.30 percent of the total weight of the four monomers into a Hastelloy polymerization kettle, and keeping the mixture at 150 ℃ for 8 hours; heating to 320 ℃ at the speed of 1.0 ℃/min, and preserving heat for 3 h; flushing 0.9MPa nitrogen into a polymerization kettle, discharging the prepolymer through a 10-hole discharge valve with the diameter of 4mm, crushing, sieving with a 30-mesh sieve, and drying at 160 ℃ for 3 hours to obtain the prepolymer; and carrying out solid phase polycondensation on the prepared prepolymer in a rotary kiln at 320 ℃ for 48h under the protection of nitrogen to prepare the liquid crystal polyarylate.

Comparative example 1

This comparative example differs from example 7 only in that 74 mol% of p-hydroxybenzoic acid, 13 mol% of hydroquinone, 12.2 mol% of biphenyldicarboxylic acid and 0.8 mol% of 4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid were used as monomers, and the other preparation procedures were the same as in example 7.

Comparative example 2

This comparative example differs from example 7 only in that the monomer ratios of 74 mol% of p-hydroxybenzoic acid, 13 mol% of hydroquinone, 9.6 mol% of biphenyldicarboxylic acid and 3.4 mol% of 4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid were used, and the other preparation procedures were the same as in example 7.

Comparative example 3

This comparative example is different from example 7 only in that 74 mol% of p-hydroxybenzoic acid, 13 mol% of hydroquinone and 13 mol% of biphenyldicarboxylic acid were used as monomers, and the other preparation processes were the same as example 7.

Comparative example 4

This comparative example differs from example 7 only in that, instead of 2-methylaminobenzothiazole, an equimolar amount of the catalyst sodium acetate is used and the other preparation steps are the same as in example 7.

Application example

The liquid crystal polyarylate prepared by the method is prepared into a film by adopting a blow molding method, and the specific process is as follows:

putting the liquid crystal polyarylate into a double-screw extruder with the temperature of 320 ℃ for melting plasticization, then extruding the liquid crystal resin in a molten state into a cylindrical tube blank through an annular die head, simultaneously injecting compressed air into the tube blank to further blow up the tube blank, and cooling by side blowing at 45 ℃; then drafting and winding to prepare a liquid crystal polyarylate nascent film;

heating the nascent film and aluminum foil with thickness of 50 μm at 280 deg.C under pressure of 10kg/cm²Pressing the film at a speed of 3m/min in a hot rolling device equipped with a heat-resistant rubber roller and a heating metal roller to prepare a laminate of a thermoplastic liquid crystalline polyarylate film/aluminum foil, and placing the laminate in a heat treatment furnace at 300 ℃ for 30 seconds; under the protection of nitrogen, the mixture is subjected to heat treatment at 250 ℃ for 18 h; and then, peeling the aluminum foil to obtain the finished liquid crystal polyarylate film.

The following performance tests were conducted for examples 5 to 8 and comparative examples 1 to 4, and the test results are shown in Table 2:

(1) tensile strength: the liquid crystalline polyarylate was molded into a dumbbell-shaped specimen having a thickness of 2.0mm by an injection molding machine. The tensile strength was measured according to ISO 527-2 at a traction rate of 5 mm/min.

(2) Dielectric constant and dielectric dissipation factor: a bar-shaped specimen having a length of 85mm, a width of 1.75mm and a thickness of 1.75mm was prepared from the liquid-crystalline polyarylate by using an injection molding machine. The test was carried out at 5GHz according to IEC 62631-2-1.

(3) Impact strength: liquid crystalline polyarylate was prepared into test pieces having a length of 64mm, a width of 12.7mm and a thickness of 2.0mm using an injection molding machine, and the Izod impact strength was measured according to ASTM D256.

(4) Melt tension: a liquid crystalline polyarylate was melt-extruded at a screw rotation speed of 20r/min and at a temperature of 5 ℃ or higher than the melting temperature by using a torque rheometer (model HAAK PolyLab OS) having a screw diameter of 19mm, and the sample was drawn into a filament shape by automatically increasing the speed by a variable speed winder, and the tension (unit: mN) at the time of breaking was measured.

Table 2: results of property test of the liquid-crystalline polyarylates prepared in examples 5 to 8 and comparative examples 1 to 4:

film formation of liquid crystalline polyarylate: "+ +" indicates the best film forming stability, "+" indicates better film forming, and "-" indicates poor film forming.

As can be seen from Table 2, the liquid crystalline polyarylate prepared by the formulation and the preparation method of the present invention has better impact strength and melt tension, and when the monomer 4- (4-carboxy-3-fluorophenyl) -2-fluorobenzoic acid is controlled within the mol% of the range (1.2 to 3.0) of the present invention, a balance between the impact strength and the melt tension can be obtained, and when the range is exceeded, one of the properties is reduced to various degrees. In addition, the conventional catalyst is adopted to replace the catalyst 2-methylamino benzothiazole, side reactions are increased in the polymerization process, and the obtained liquid crystal polyarylate has low melt tension and can not meet the film preparation requirement.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.