阅读说明：本技术 一种聚芳酰胺液晶聚合物及其制备方法和应用 (Polyaramide liquid crystal polymer and preparation method and application thereof ) 是由 王贤文 黄文刚 张海良 饶先花 谭麟 黄华鹏 胡三友 杨思思 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种聚芳酰胺液晶聚合物及其制备方法和应用,通过二甲酰氯单体与芳香型二醚二胺、对苯二胺共聚得到一系列新型的聚芳酰胺液晶聚合物,分子主链结构中含有柔性醚键,降低分子链刚性和分子链间作用力,从而降低了熔融温度,提高加工流动性,可以形成稳定的液晶态,加工成型性好。本发明的聚芳酰胺液晶聚合物是一种向列型的主链型热致性液晶聚合物,具有优异的力学性能和热稳定性,加工性能好,适用于热塑加工,可作为薄膜材料和树脂基复合材料应用于航天航空、精密机械、石油化工、汽车薄壁耐热制件、超薄壁化电气零部件或食品餐具领域。(The invention discloses a polyaramide liquid crystal polymer and a preparation method and application thereof.A series of novel polyaramide liquid crystal polymers are obtained by copolymerizing a diformyl chloride monomer, aromatic diether diamine and p-phenylenediamine, and the main molecular chain structure contains flexible ether bonds to reduce the molecular chain rigidity and the acting force between molecular chains, thereby reducing the melting temperature, improving the processing fluidity, forming a stable liquid crystal state and having good processing formability. The polyaramide liquid crystal polymer is a nematic main chain thermotropic liquid crystal polymer, has excellent mechanical property and thermal stability and good processing property, is suitable for thermoplastic processing, and can be used as a film material and a resin-based composite material to be applied to the fields of aerospace, precision machinery, petrochemical industry, automobile thin-wall heat-resistant products, ultrathin-wall electrical parts or food tableware.)

1. A polyaramide liquid crystal polymer is characterized by being composed of the following repeating units of formula (I) to formula (IV):

formula (I)

Formula (II)

Formula (III)

Formula (IV)

The content of the repeating unit of the formula (I) is less than or equal to 100mol% and is not equal to 0, wherein the mol total amount of the repeating units of the formula (I) to the formula (IV) is 100 mol%; the content of the repeating unit of the formula (II) is less than 100 mol%; the content of the repeating unit of the formula (III) is less than 100 mol%; the content of the repeating unit of the formula (IV) is less than 100 mol%;

wherein, the structure of R1 is selected from any one or more of formula (V), formula (VI) or formula (VII); preferably, the structure of R1 is selected from any one or more of formula (V);

formula (V)

Formula (VI)

Formula (VII)

Wherein R is₂Is selected from、、Any one of a heterocyclic aromatic group or a polycyclic aromatic group; n is a positive integer greater than or equal to 1; the R is₃Is selected from、、、、、、、Oxygen atom, sulfur atom or a linear or branched aliphatic divalent group of more than 6 carbon atoms, wherein n₂Is a positive integer of 1-6; the heterocyclic aromatic group is an aromatic group in which atoms constituting a ring contain at least one hetero atom in addition to carbon atoms; the polycyclic aromatic group means an aromatic group in which two or more benzene rings are connected in a fused ring form.

2. The polyaramid liquid crystal polymer according to claim 1, wherein the content of the repeating unit of the formula (i) is 50mol% to 100 mol%; the content of the repeating unit of the formula (II) is less than or equal to 50 mol%; the content of the repeating unit of the formula (III) is less than or equal to 50 mol%; the content of the repeating unit of the formula (IV) is less than or equal to 50 mol%; preferably, the content of the repeating units in the formulas (II), (III) and (IV) is not equal to 0.

3. The polyaramid liquid crystal polymer according to claim 1, wherein the polyaramid liquid crystal polymer has a weight average molecular weight of 2 to 10 ten thousand; preferably, the weight average molecular weight of the polyaramide liquid crystal polymer is 5-10 ten thousand; more preferably, the weight average molecular weight of the polyaramide liquid crystal polymer is 6 to 8 ten thousand.

4. The polyaramid liquid crystal polymer of claim 1, wherein the intrinsic viscosity of the polyaramid liquid crystal polymer is from 0.8dL/g to 2.5 dL/g.

5. The method for producing a polyaramid liquid crystal polymer according to any one of claims 1 to 4, characterized by comprising the steps of:

introducing nitrogen into a reactor with a stirring device, exhausting air in the reactor, adding a diamine monomer to dissolve in a polar aprotic solvent, adding an acid-binding agent and an end-capping agent, adding a diformyl chloride monomer in an amount equal to that of the diamine monomer, reacting for 3-7 h under an ice bath condition of-20 ℃ to-5 ℃, and after the reaction is stopped, performing elutriation, crushing, washing and drying to obtain a polyaramide liquid crystal polymer;

wherein the molar ratio of the polar aprotic solvent to the diamine monomer is (3-10): 1; the molar ratio of the acid-binding agent to the diamine monomer is (2-8): 1; the molar ratio of the end-capping agent to the diamine monomer is (0.01-0.05): 1.

6. the method for preparing polyaramid liquid crystal polymer according to claim 5, wherein the diamine monomer is at least one selected from p-phenylenediamine or aromatic diether diamine; the diformyl chloride monomer is at least one of terephthaloyl chloride or isophthaloyl chloride; the polar aprotic solvent is selected from at least one of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide or dimethyl sulfoxide; the acid-binding agent is selected from at least one of pyridine, 2-methylpyridine, diethylamine or triethylamine; the end-capping reagent is selected from at least one of benzoyl chloride or aniline.

7. The method for preparing polyaramid liquid crystal polymer according to claim 6, wherein the aromatic diether diamine is a compound containing、、Diethanediamine having any one structure of a heterocyclic aromatic group or a polycyclic aromatic group; n is a positive integer greater than or equal to 1; the R is₃Is selected from、、、、、、、Oxygen atom, sulfur atom or a linear or branched aliphatic divalent group of more than 6 carbon atoms, wherein n₂Is a positive integer of 1-6; the heterocyclic aromatic group is an aromatic group in which atoms constituting a ring contain at least one hetero atom in addition to carbon atoms; the polycyclic aromatic group means an aromatic group in which two or more benzene rings are connected in a fused ring form.

8. The method for preparing a polyaramid liquid crystal polymer according to claim 7, wherein the aromatic diether diamine is selected from any one or more of bisphenol A diether diamine, bisphenol S diether diamine, biphenol diether diamine, 6 ' -dihydroxy-2, 2 ' -bipyridine diether diamine, 2, 6-naphthalenediol diether diamine, bis (4,4' -dihydroxy) phenylethynyl diether diamine, dihydroxy diphenyl ethylene, dihydroxy benzophenone diether diamine, dihydroxy diphenyl ether diether diamine, dihydroxy diphenyl sulfide diether diamine, or phenol diether diamine.

9. The use of the polyaramid liquid crystal polymer according to any one of claims 1 to 4 as a film material or a resin composite material.

10. The use of the polyaramid liquid crystal polymer according to claim 9, which is applied to the fields of aerospace, precision machinery, petrochemical industry, automobile thin-wall heat-resistant parts, ultra-thin-wall electrical parts or food tableware.

Technical Field

The invention relates to the field of high molecular materials, in particular to a polyaramide liquid crystal polymer and a preparation method and application thereof.

Background

The polyaramid (aramid) fiber has a series of excellent performances such as ultrahigh strength, ultrahigh modulus, high temperature resistance, corrosion resistance, flame retardance, fatigue resistance, low linear expansion coefficient, good dimensional stability and the like, is mainly used for manufacturing high-strength and high-temperature-resistant organic fibers, and can also be used for manufacturing film reinforcing materials, so that the polyaramid (aramid) fiber is widely applied to high-performance composite material parts (such as rocket engine shells, aircraft engine cabins, fairings, rudders and the like), ships (such as aircraft carriers, nuclear submarines, yachts, lifeboats and the like), automobiles (such as tire cords, high-pressure hoses, friction materials, high-pressure gas cylinders and the like) and heat-resistant transportation belts, sports equipment and the like in the field of aerospace.

However, the conventional polyaramid resin is difficult to dissolve and infusible due to the regularity and rigidity of a molecular main chain and the existence of hydrogen bonds between molecules, and has poor industrial processing performance, so that the development and the application of products are limited. Research shows that the solubility of the polyaramid can be improved by introducing flexible groups, groups with larger volume and distorted non-coplanar structures into the main chain of a polymer molecule, but the heat resistance of the polyaramid is often reduced. Chinese patent applications CN109134847A and CN109134848A disclose a poly-aromatic polyamide, in which side chains are introduced by poly-copolymerization to reduce the regularity of the aromatic polyamide and lower the crystallinity thereof to improve the solubility thereof; however, the process of introducing the side chain is complex, and the steric hindrance of the side chain group greatly affects the reactivity of the monomer.

In the prior art, the processability of the polyaramide is mainly improved by improving the solubility of the polyaramide, and along with the continuous development of the 5G technology, the requirement on thermoplastic composite materials is more and more increased, so that the problem that the polyaramide material is difficult to be subjected to thermoplastic processing is solved, the application of the polyaramide material is further widened, and the method is the main research direction of the invention.

Disclosure of Invention

The invention aims to provide a polyaramide liquid crystal polymer which has excellent mechanical property and heat resistance, has good processing formability and is suitable for thermoplastic processing.

Another object of the present invention is to provide a method for producing the liquid crystalline polyaramid polymer.

The invention is realized by the following technical scheme:

a polyaramide liquid crystal polymer is composed of the following repeating units of formula (I) to formula (IV):

formula (I)

Formula (II)

Formula (III)

Formula (IV)

The content of the repeating unit of the formula (I) is less than or equal to 100mol% and is not equal to 0, wherein the mol total amount of the repeating units of the formula (I) to the formula (IV) is 100 mol%; the content of the repeating unit of the formula (II) is less than 100 mol%; the content of the repeating unit of the formula (III) is less than 100 mol%; the content of the repeating unit of the formula (IV) is less than 100 mol%;

wherein, the structure of R1 is selected from any one or more of formula (V) and formula (VI);

formula (V)

Formula (VI)

Formula (VII)

Wherein R is₂Is selected from、、Any one of a heterocyclic aromatic group or a polycyclic aromatic group; n is a positive integer greater than or equal to 1; the R is₃Is selected from、、、、、、、Oxygen atom, sulfur atom or linear or branched with more than 6 carbon atomsAny one of aliphatic divalent groups, wherein n is₂Is a positive integer of 1-6; the heterocyclic aromatic group is an aromatic group in which atoms constituting a ring contain at least one hetero atom in addition to carbon atoms; the polycyclic aromatic group means an aromatic group in which two or more benzene rings are connected in a fused ring form.

Preferably, the content of the repeating unit of the formula (I) is 50-100 mol%; the content of the repeating unit of the formula (II) is less than or equal to 50 mol%; the content of the repeating unit of the formula (III) is less than or equal to 50 mol%; the content of the repeating unit of the formula (IV) is less than or equal to 50 mol%; more preferably, the content of the repeating units of the formulae (II), (III) and (IV) is not equal to 0.

Preferably, the structure of R1 is selected from any one or more of formula (V), and the monomer with ether bond at para-position of benzene ring has higher reactivity.

The main chain structure of the polyaramide liquid crystal polymer contains flexible ether bonds, so that the rigidity of molecular chains can be reduced, and the acting force between molecular chains can be reduced, thereby reducing the melting temperature, improving the processing fluidity and forming a stable liquid crystal state. The polyaramide liquid crystal polymer is a nematic main chain thermotropic liquid crystal polymer, has the intrinsic viscosity of 0.8 dL/g-2.5 dL/g, has good processing formability and is suitable for thermoplastic processing.

The invention forms a series of molecular controllable thermoplastic polyaramide liquid crystal polymers through the end capping of the end capping agent, has concentrated molecular weight distribution and high stability, and is more suitable for long-term use under various polar conditions. The weight average molecular weight of the polyaramide liquid crystal polymer is 2-10 ten thousand; preferably, the weight average molecular weight of the polyaramide liquid crystal polymer is 5-10 ten thousand; more preferably, the weight average molecular weight of the polyaramide liquid crystal polymer is 6 to 8 ten thousand.

The invention also provides a preparation method of the polyaramide liquid crystal polymer, which comprises the following steps:

introducing nitrogen into a reactor with a stirring device, exhausting air in the reactor, adding a diamine monomer to dissolve in a polar aprotic solvent, adding an acid-binding agent and an end-capping agent, adding a diformyl chloride monomer in an amount equal to that of the diamine monomer, reacting for 3-7 h under an ice bath condition of-20 ℃ to-5 ℃, and after the reaction is stopped, performing elutriation, crushing, washing and drying to obtain a polyaramide liquid crystal polymer;

wherein the molar ratio of the polar aprotic solvent to the diamine monomer is (3-7): 1; the molar ratio of the acid-binding agent to the diamine monomer is (2-5): 1; the molar ratio of the end-capping agent to the diamine monomer is (0.01-0.05): 1.

the diamine monomer is at least one of p-phenylenediamine or aromatic diether diamine; the aromatic diethanediamine of the invention is a compound containing、、Diethanediamine having any one structure of a heterocyclic aromatic group or a polycyclic aromatic group; n is a positive integer greater than or equal to 1; the R is₃Is selected from、、、、、、、Oxygen atom, sulfur atom or a linear or branched aliphatic divalent group of more than 6 carbon atoms, wherein n₂Is a positive integer of 1-6; the heterocyclic aromatic group is an aromatic group in which atoms constituting a ring contain at least one hetero atom in addition to carbon atoms; the polycyclic aromatic group means an aromatic group in which two or more benzene rings are connected in a fused ring form.

Specifically, the aromatic diether diamine of the present invention may be any one or more selected from bisphenol a diether diamine, bisphenol S diether diamine, biphenol diether diamine, 6 ' -dihydroxy-2, 2 ' -bipyridyl diether diamine, 2, 6-naphthalenediol diether diamine, bis (4,4' -dihydroxy) phenylethynyl diether diamine, dihydroxystilbene, dihydroxybenzophenone diether diamine, dihydroxydiphenyl ether diether diamine, dihydroxydiphenyl sulfide diether diamine, or phenol diether diamine.

The aromatic diethanediamine of the present invention can be obtained commercially; can also be prepared by a conventional one-step synthesis method or a two-step hydrogenation reduction method.

The diformyl chloride monomer is at least one of terephthaloyl chloride or isophthaloyl chloride.

The polar aprotic solvent is selected from at least one of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.

The acid-binding agent is selected from at least one of pyridine, 2-methylpyridine, diethylamine or triethylamine.

The end-capping reagent is selected from at least one of benzoyl chloride or aniline.

The invention also provides application of the polyaramide liquid crystal polymer, and the polyaramide liquid crystal polymer can be used as a film material or a resin composite material to be applied to the fields of aerospace, precision machinery, petrochemical industry, automobile thin-wall heat-resistant parts, ultrathin-wall electrical parts or food tableware.

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

the invention obtains a series of novel polyaramide liquid crystal polymers by copolymerizing the diformyl chloride monomer, the aromatic diether diamine and the p-phenylenediamine, the main chain structure of the molecule contains flexible ether bonds, and the molecular chain rigidity and the acting force between molecular chains can be reduced, thereby reducing the melting temperature, improving the processing fluidity, forming a stable liquid crystal state, having good processing formability and being particularly suitable for thermoplastic processing.

The polyaramide liquid crystal polymer is a nematic main chain thermotropic liquid crystal polymer, has excellent mechanical property and thermal stability and good processing property, is suitable for thermoplastic processing, further widens the application of polyaramide materials, and can be used as a film material and a resin matrix composite material.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

The raw materials or reagents used in the examples of the present invention and comparative examples are commercially available, but are not limited to these materials.

Preparation of examples and comparative examples:

according to the mixture ratio of table 1, nitrogen is introduced into a reactor with a stirring device, air in the reactor is exhausted, diamine monomer is added to dissolve in polar aprotic solvent, acid binding agent and end capping agent are added, and then diformyl chloride monomer is added to react for 3.5h under the ice bath condition of-15 ℃, and after the reaction is stopped, the polyaramide liquid crystal polymer is obtained through elutriation, crushing, washing and drying.

Relevant performance test methods or standards:

(1) determination of weight average molecular weight: measured by an Agilent gel chromatograph, the test conditions are as follows: DMF was used as the mobile phase, and was injected at 60 ℃ in an amount of 20. mu.l.

(2) Measurement of intrinsic viscosity: measuring the viscosity of the polymer solution by an Ubbelohde viscometer, and calculating the intrinsic viscosity [ eta ] of the polymer by a one-point method; for the specific operation of the test of intrinsic viscosity: a polymer sample is weighed and dissolved in N-methylpyrrolidone to prepare a solution with the concentration of 0.5 g/dL. The intrinsic viscosity of the polymer was measured by the Ubbelohde viscosity method in a constant temperature water bath at 30 ℃.

(3) Melt index: and (3) testing conditions are as follows: 365 ℃ and 5KG, according to ISO 1133.

(4) Heat distortion temperature: the test method is ISO 75-1/-2;

(5) mechanical properties (tensile strength, bending strength): the test method is according to ISO 527, ISO 178.

Table 1: the molar ratio of the reagents in examples 1-9 and comparative examples 1-3 and the product performance test results.

Table 1 is shown below:

the embodiments show that the polyaramide liquid crystal polymer has the intrinsic viscosity less than 2.5dL/g, the heat distortion temperature more than 175 ℃, good processability, good heat resistance and excellent mechanical property. Compared with the example 1, the polyaramid liquid crystal polymer prepared by only selecting the isophthaloyl dichloride monomer has low intrinsic viscosity and heat distortion temperature, poor heat resistance and poor mechanical property. Comparative example 2 compared to example 1, too much capping agent was added, resulting in a polymer with too low a molecular weight to be thermoformed. In comparison with example 1, in comparative example 3, the molecular weight of the polymer was controlled without adding a terminal-blocking agent, and the polymer had high intrinsic viscosity and glass transition temperature, poor processability, and could not be thermoformed.