CN112608459B - Thermotropic aromatic liquid crystal copolyester and preparation method thereof - Google Patents
Thermotropic aromatic liquid crystal copolyester and preparation method thereof Download PDFInfo
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/60—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from the reaction of a mixture of hydroxy carboxylic acids, polycarboxylic acids and polyhydroxy compounds
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Abstract
The invention discloses a thermotropic aromatic liquid crystal copolyester and a preparation method thereof, wherein the thermotropic aromatic liquid crystal copolyester comprises a main chain which is copolymerized by rigid mesomorphic elements and polyester granules, and end-sealing groups are phenylacetylene or norbornene acetylene groups; mesogenic units are selected from resorcinol, terephthalic acid and 2, 7-naphthalene dicarboxylic acid; and 4' -hydroxybiphenyl-4-carboxylic acid containing both a terminal carboxyl group A and a terminal hydroxyl group B. The thermotropic aromatic liquid crystal copolyester has lower melt processing temperature and flame-retardant anti-dripping performance, can effectively reduce life and property loss caused by fire, has wide application prospect in the fields of civil textiles and high-temperature protective materials, has controllable molecular weight in the polymerization process, is simpler, more efficient and environment-friendly in preparation process, and does not generate harmful gas during combustion.
Description
Technical Field
The invention relates to the field of high polymer materials, in particular to thermotropic aromatic liquid crystal copolyester and a preparation method thereof.
Background
The semi-aromatic polyester is used as a high polymer material with wide application, and has wide application in civil and industrial aspects due to the characteristics of high strength, high modulus and low water absorption. Polyester fiber, also known as terylene, occupies most of the share of chemical fiber industry. The class of polyesters that are marketed includes PET, PBT, PTT, and the like. As the polymer can be oxidized and degraded at high temperature, once the polymer is burnt, a fire is easily formed, and the life and property safety of people can be seriously influenced. Therefore, the flame retardant property of the polyester material is improved, and the flame retardant property has great significance.
The patent CN107938014A discloses a preparation method of a flame-retardant thermotropic polyarylate liquid crystal fiber, wherein a thermotropic liquid crystal polyarylate slice is obtained by introducing a phosphorus-containing aromatic unit into a main chain, the slice is spun into filaments by melt extrusion, and finally the flame-retardant thermotropic polyarylate liquid crystal fiber is prepared by post-treatment. The process flow is simple, the fiber has good flame retardant effect, but white smoke and molten drops can be generated during combustion due to the phosphorus flame retardant. Therefore, in order to reduce the dripping of the flame-retardant polyester fiber and the harm to the human body, the research on a new phosphorus-free flame-retardant polyester material is urgently needed. On the other hand, if the main chain of the liquid crystalline polyarylate is a rigid linear structure, it needs to be melted at a high temperature (300 ℃ or higher) to be molded, and the liquid crystalline polyarylate monomer is relatively expensive, which further increases the production cost.
Disclosure of Invention
The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermotropic aromatic liquid crystalline copolyester having low melting point, anti-dripping property, and no harmful gas generation during combustion, and a method for preparing the same.
The purpose of the invention is realized as follows:
the thermotropic aromatic liquid crystal copolyester comprises a main chain, a main chain and a side chain, wherein the main chain is formed by copolymerizing rigid mesomorphic elements and polyester granules, and end-sealing groups are phenylacetylene or norbornene acetylene groups; the mesogenic unit is composed of a full aromatic diphenol monomer, a full aromatic diacid monomer and an AB type full aromatic monomer containing a terminal carboxyl group A and a terminal hydroxyl group B;
the wholly aromatic diphenol monomer is resorcinol;
wholly aromatic diacid monomers are terephthalic acid and 2, 7-naphthalenedicarboxylic acid;
meanwhile, the AB type wholly aromatic monomer containing the terminal carboxyl group A and the terminal hydroxyl group B is 4' -hydroxybiphenyl-4-carboxylic acid.
The polyester particles in the thermotropic aromatic liquid crystal copolyester are one or more of polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate.
The phenylacetylene or norbornene acetylene group in the thermotropic aromatic liquid crystal copolyester is one or more of the following compounds:
wherein Y is amino or imino; z is hydroxyl, carboxyl, ester group or carbonyl.
The polyester particles in the thermotropic aromatic liquid crystal copolyester are polytrimethylene terephthalate;
the end capping group is
The structural formula of the thermotropic aromatic liquid crystal copolyester in the thermotropic aromatic liquid crystal copolyester is as follows:
wherein m is 90-100, and n is 2-20.
The molecular weight of the thermotropic aromatic liquid crystal copolyester in the thermotropic aromatic liquid crystal copolyester is 1000 to 10000 g/mol.
The invention also provides a preparation method of the thermotropic aromatic liquid crystal copolyester, which comprises the following steps:
(1) adding hydroquinone, terephthalic acid, 2, 7-naphthalenedicarboxylic acid, 6-hydroxy-2-naphthoic acid, polyester particles, a compound containing phenylacetylene or norbornene acetylene groups, acetic anhydride and a catalyst in a molar ratio of 10-40: 80-20: 100-500: 2-8 into a reactor; performing acetylation reaction for 30-60 min under the protection of inert gas at the temperature of 120-150 ℃;
(2) heating to 300-340 ℃ at a heating rate of 0.5-1.5 ℃/min, and carrying out ester exchange reaction for 1-3 h;
(3) reacting for 10-30 min at the temperature of 300-320 ℃ and the vacuum degree of 1-3 mbar;
(4) and (3) cooling to room temperature in an inert gas atmosphere, grinding the product obtained in the step (3) into powder, and performing post-polycondensation reaction for 18-36 h under the conditions that the temperature is 200-260 ℃ and the vacuum degree is 1-3 mbar.
In the preparation method of the thermotropic aromatic liquid crystal copolyester, the catalyst is one or more of sodium acetate, potassium acetate, zinc acetate, antimony trioxide, tetrabutyl titanate and germanium dioxide, and/or the mass of the catalyst is 0.1-0.5% of the total mass of all the raw materials;
in the preparation method of the thermotropic aromatic liquid crystal copolyester, the molar quantity of acetic anhydride is more than the total molar quantity of hydroxyl in a full aromatic diphenol monomer, a full aromatic diacid monomer, an AB type full aromatic monomer containing a terminal carboxyl group A and a terminal hydroxyl group B, polyester particles and a compound containing phenylacetylene or norbornene acetylene groups.
The preparation method of the thermotropic aromatic liquid crystal copolyester comprises the following steps:
(1) adding resorcinol, terephthalic acid, 2, 7-naphthalenedicarboxylic acid, 4' -hydroxybiphenyl-4-carboxylic acid, PTT particles, acetic acid 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) phenyl acetate, 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) benzoic acid and 155 ml of acetic anhydride in a molar ratio of 40:24:16:20:200:6:6, using 0.5 wt% of sodium acetate as a catalyst, a flask equipped with a sealed glass paddle stirrer, a nitrogen inlet pipe and an insulated distillation head, the reaction mixture was acetylated at 140 ℃ for 40min in a flowing sand bath with a nitrogen flow;
(2) heating to 300 ℃ at the heating rate of 0.5 ℃/min to perform ester exchange reaction for 2 h;
(3) slowly vacuumizing the reaction system, and keeping the vacuum degree at 2mbar and the temperature at 310 ℃ for 20 min;
(4) and (4) cooling the opaque melt obtained in the step (3) to room temperature, removing the product from the flask, grinding the product into fine powder, and carrying out solid-state polycondensation reaction for 18 hours at 230 ℃ and under the vacuum degree of 2 mbar.
Naphthalene monomers are introduced into a molecular chain of the thermotropic aromatic liquid crystal copolyester material copolymer to destroy the linearity of the main chain, the molecular chain is in a semi-aromatic structure and has lower melting processing temperature compared with a straight-chain fully aromatic liquid crystal material, on the other hand, two ends of the molecular chain are blocked by active groups which can be thermally cured such as phenylacetylene or norbornene acetylene, and the like, and can generate cycloaddition reaction to form a solidified cross-linked network structure under the high-temperature environment (350-.
Compared with the prior art, the invention has the following technical effects:
(1) the high molecular chain of the thermotropic aromatic liquid crystal copolyester material is in a semi-aromatic structure and has lower melting processing temperature, and a cross-linked network structure formed after the active end group is introduced for thermosetting reaction has excellent flame-retardant and anti-dripping performance, and can effectively reduce life and property loss caused by fire, so the thermotropic aromatic liquid crystal copolyester material has wide application prospect in the fields of civil textiles and high-temperature protection materials.
(2) The thermotropic aromatic liquid crystal copolyester has controllable molecular weight in the polymerization process, and can be obtained into materials with different molecular weights according to requirements.
(3) The thermotropic aromatic liquid crystal copolyester prepared by the invention does not contain any solvent, no small molecules are generated in the curing process, thermotropic liquid crystal polyarylate plates and fibers can be prepared by hot pressing or melt spinning, and the solvent is not required to be removed in the process, so that the preparation process is simpler, more efficient and more environment-friendly;
(4) the thermotropic aromatic liquid crystal copolyester prepared by the invention does not contain a phosphorus flame retardant, so that harmful gas is not generated during combustion.
Drawings
FIG. 1 is a DSC chart of example 1 and comparative examples 1-2.
Detailed Description
The invention will be further explained with reference to the drawings.
The starting materials used in example 1 and comparative examples 1-2 below were purchased from Shanghai Bailingwei chemical technology, Inc., 100 g/bottle, and had a purity of > 98%.
Example 1
The thermotropic aromatic liquid crystal copolyester of the embodiment has the following chemical structural formula:
wherein n is 2-20, and m is 90-100;
resorcinol, terephthalic acid, 2, 7-naphthalenedicarboxylic acid, 4' -hydroxybiphenyl-4-carboxylic acid, PTT particles, phenyl acetate 4- (1, 3-dioxo-2H-4, 7-methylisoindol-2-yl) acetate, 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) benzoic acid, and 155 ml acetic anhydride were added in a 250 ml three-necked round-bottomed flask in a molar ratio of 40:24:16:20:200:6:6, using 0.5% by weight of sodium acetate as a catalyst. The flask was fitted with a sealed glass paddle stirrer, a nitrogen inlet and an insulated distillation head. The reaction mixture was acetylated at 140 ℃ for 40min in a sand bath with a nitrogen flow and then raised to 300 ℃ at a temperature rise rate of 0.5 ℃/min for 2h transesterification. At this time, the reaction system was slowly evacuated to a vacuum of 2mbar and a temperature of 310 ℃ for 20 min. The opaque melt was cooled to room temperature and the product was removed from the flask and ground to a fine powder. The sample of the embodiment is obtained after solid state polycondensation reaction for 18 hours at 230 ℃ and under the vacuum degree of 2 mbar.
Comparative example 1
4, 4' -dihydroxybiphenyl, terephthalic acid, 2, 6-naphthalenedicarboxylic acid, p-hydroxybenzoic acid, N- (3-carboxyphenyl) -4-phenylethynylphthalimide, N- (3-hydroxyphenyl) -4-phenylethynylphthalimide, as well as 150 ml of acetic anhydride and 0.1 wt% potassium acetate were added in a 250 ml three-necked round bottom flask in a molar ratio of 10:8:2:80:8: 8. The flask was fitted with a sealed glass paddle stirrer, a nitrogen inlet and an insulated distillation head. The reaction mixture was acetylated at 140 ℃ for 40min in a fluid sand bath with a moderate nitrogen flow and then raised to 300 ℃ at a heating rate of 0.5 ℃/min for 2h transesterification. At this point, the reaction system was slowly evacuated to a vacuum of 2mbar and a temperature of 310 ℃ for 20 min. The opaque melt was cooled to room temperature and the product was removed from the flask and ground to a fine powder. Performing solid state polycondensation reaction for 24 hours at 230 ℃ and under the vacuum degree of 2mbar to obtain a target product with the chemical formula as follows:
comparative example 2
4, 4' -dihydroxybiphenyl, bis (p-carboxyphenyl) phenylphosphinate, 2, 6-naphthalenedicarboxylic acid, p-hydroxybenzoic acid, 150 ml acetic anhydride and 0.1% by weight potassium acetate were added in a 250 ml three-necked round bottom flask in a molar ratio of 10:8:2: 80. The flask was fitted with a sealed glass paddle stirrer, a nitrogen inlet and an insulated distillation head. The reaction mixture was acetylated at 140 ℃ for 40min in a fluid sand bath with a moderate nitrogen flow and then raised to 300 ℃ at a heating rate of 0.5 ℃/min for 2h transesterification. At this time, the reaction system was slowly evacuated to a vacuum of 2mbar and a temperature of 310 ℃ for 20 min. The opaque melt was cooled to room temperature and the product was removed from the flask and ground to a fine powder. Performing solid state polycondensation reaction for 24 hours at 230 ℃ and under the vacuum degree of 2mbar to obtain a target product with the chemical formula as follows:
performance testing
The thermal properties of the products were tested by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA), and the flame retardant properties were determined by testing the vertical burning of the products while the intrinsic viscosity of the products was tested, the thermal and flame retardant properties and the intrinsic viscosity test results are shown in tables 1 and 2, respectively:
TABLE 1 results of the differential scanning calorimetry
TABLE 2 thermogravimetric analysis test results
The DSC curves of comparative examples 1-2 and example 1 are shown in FIG. 1.
As can be seen from fig. 1 and table 1, the melting point of the pure thermotropic liquid crystal high polymer of comparative example 1 is 267 ℃, the melting point of the pure thermotropic liquid crystal high polymer of comparative example 2 is 270 ℃, and the melting point of the copolymer of example 1 is lower than that of comparative examples 1-2 and PET (Tm is 250-260 ℃), which can reduce the molding production cost of the copolyester material to some extent; meanwhile, the thermal decomposition temperature Td 5% of the liquid crystal copolyester is above 370 ℃, and the liquid crystal copolyester has high thermal stability.
The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.
Claims (4)
1. The thermotropic aromatic liquid crystal copolyester is characterized by having the following structural formula:
wherein m is 90-100, and n is 2-20;
prepared by adding resorcinol, terephthalic acid, 2, 7-naphthalenedicarboxylic acid, 4' -hydroxybiphenyl-4-carboxylic acid, PTT particles, acetic acid 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) acetic acid phenyl ester and 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) benzoic acid in a molar ratio of 40:24:16:20:200:6: 6.
2. The thermotropic aromatic liquid-crystalline copolyester of claim 1, having a molecular weight of 1000 to 10000 g/mol.
3. The method for preparing the thermotropic aromatic liquid-crystalline copolyester of claim 1, comprising the steps of:
(1) adding resorcinol, terephthalic acid, 2, 7-naphthalenedicarboxylic acid, 4' -hydroxybiphenyl-4-carboxylic acid, PTT particles, acetic acid 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) phenyl acetate, 4- (1, 3-dioxo-1, 3,3a, 4,7,7 a-hexahydro-2H-4, 7-methylisoindol-2-yl) benzoic acid and 155 ml of acetic anhydride in a molar ratio of 40:24:16:20:200:6:6, using 0.5 wt% of sodium acetate as a catalyst, a flask equipped with a sealed glass paddle stirrer, a nitrogen inlet pipe and an insulated distillation head, introducing a nitrogen flow, and acetylating the reaction mixture in a flowing sand bath at 140 ℃ for 40 min;
(2) heating to 300 ℃ at the heating rate of 0.5 ℃/min to perform ester exchange reaction for 2 h;
(3) slowly vacuumizing the reaction system, and keeping the vacuum degree at 2mbar and the temperature at 310 ℃ for 20 min;
(4) and (4) cooling the opaque melt obtained in the step (3) to room temperature, removing the product from the flask, grinding the product into fine powder, and carrying out solid-state polycondensation reaction for 18 hours at 230 ℃ and under the vacuum degree of 2 mbar.
4. The method for preparing the thermotropic aromatic liquid-crystalline copolyester according to claim 3, wherein the mass of the catalyst is 0.1 to 0.5 percent of the total mass of all raw materials.
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| US6268419B1 (en) * | 1999-03-30 | 2001-07-31 | Nippon Petrochemical Co., Ltd | Method of producing thermotropic liquid crystalline copolyester, thermotropic liquid crystalline copolyester composition obtained by the same method, and molding made of the same composition |
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Effective date of registration: 20221114 Address after: No. 1128, Wenhui Road, Songjiang District, Shanghai Patentee after: Shanghai Hangyong Photoelectric New Materials Co.,Ltd. Address before: 200233 room 526, 5 / F, building 33, 680 Guiping Road, Xuhui District, Shanghai Patentee before: Shanghai Sitao New Material Technology Co.,Ltd. |
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