WO2021098136A1 - Class of multi-mixed composite salt monomers having anti-oxidation stability and polybenzodiazole liquid crystal polymers, and preparations and applications thereof - Google Patents

Abstract

A class of multi-mixed composite salt monomers having anti-oxidation stability and polybenzodiazole liquid crystal polymers, and preparations and applications thereof. The structure of the multi-mixed composite salt monomer is represented by formula (I), (II) or (III). Further disclosed are a preparation method for a multi-mixed composite salt monomer, an application of the multi-mixed composite salt monomer in a self-condensation polymerization preparation of a polybenzodiazole liquid crystal polymer and fiber thereof, and a resulting polybenzodiazole liquid crystal polymer and a fiber thereof. The structure of the polybenzodiazole liquid crystal polymer is represented by formula (V), (VI) or (VII). The multi-mixed composite salt monomer integrates the structure and potential performance of a material into one, and has excellent anti-oxidation stability; the monomer is applied in the self-condensation polymerization preparation of a modified PBO composite fiber, and can effectively solve the comprehensive performance of a material, and has the advantages of having a fast polymerization speed, unique fiber coagulation device and process, high productivity, convenient operation, low costs and so on.

Description

A class of multi-mixed compound salt monomer and multi-component polybenzodiazole liquid crystal polymer with anti-oxidation stability and preparation and application thereof Technical field

The invention relates to a class of multi-mixed composite salt monomers and multi-component polybenzodiazole liquid crystal polymers with anti-oxidation stability and their preparation and application, and belongs to the technical field of new-type polymer monomers and high-performance organic fibers.

Background technique

Nowadays, the organic high-performance fiber is known as polyparaphenylene benzodioxazole (PBO), and its three excellent properties of high-strength, high-modulus, heat-resistant and flame-retardant, soft and impact-resistant are the best among organic fibers. The comprehensive performance of Zylon-HM fiber (5.8GPa tensile strength, 270GPa modulus, 68 limiting oxygen index and 650℃ decomposition temperature) has long been used as a new type of material in aerospace, national defense and military industries and special civil applications. It has received much attention from the research department and industry. Foreign countries have gradually expanded from their original use in aerospace, national defense and military industry, and anti-impact protective equipment to special civilian use (anti-radiation, high-strength ropes, sports), rail transit, and industrial use (high-temperature industrial materials, reinforcement of construction engineering materials, optical fibers) Communication cable enhancement) and more than 20 industrial fields. It is made of the key monomers 4,6-diaminoresorcinol hydrochloride (DARH) and terephthalic acid (TPA) in polyphosphoric acid (PPA) medium according to formula (1) high temperature polycondensation to prepare PBO polymerization And then dry-jet wet-spun into fibers.

However, because the key monomer DARH is difficult to source and easy to oxidize, the time for removing HCl gas is long, the anti-corrosion requirements of production equipment are very high, the process conditions and control are extremely harsh, and the semi-continuous operation is complicated. Since the monopoly of sales, there have been no reports on the industrialization of other countries and departments, and the process of localization in China has been very slow.

In order to solve the problem of easy oxidation of key monomers, low-valent metal ions Sn ²⁺ are usually added to DARH, but the content is 3500ppm as the upper limit. If the upper limit is exceeded, the polymerization reaction is dominant because the metal ions seriously affect the polymerization reaction, which makes PBO difficult. Reach ultra-high molecular weight; and, because metal ions will gradually accumulate in the process of recovery and recycling of the polymerization medium PPA, the recycling of PPA is limited.

In order to solve the problems of long degassing time and high material requirements for equipment anti-corrosion, Toyobo also developed the formula (2) in the early stage to make TPA/DAR composite salt monomer (TDH), and then polymerize spinning to prepare PBO. Trial of patented technology, but because the self-oxidation of this compound salt TDH is faster than DARH and cannot be operated, the industrialization transformation of Toyobo Company was abandoned by itself.

At the same time, Toyobo has also used AB monomer ABA homocondensation spinning to prepare PBO fiber formula (3) pilot technology. Although it has achieved no HCl gas emission and interference at the same time, the group equimolar polymerization, and the efficiency is greatly improved, but due to the method of preparing ABA by formula (4), the monomer quality is difficult to reach the polymerization level, and the cost is close to the price of PBO fiber. And lack of practicality and other issues.

The inventors have innovatively discovered the superiority of 4-(5-amino-6-hydroxybenzoxazol-2-yl)ammonium benzoate (ABAA) as an AB-type PBO monomer, which is effective according to formula (5) Applied to the manufacture of PBO fiber, it has demonstrated unique advantages. It has formed an independent intellectual property system that can realize the monopoly of production of intermediates, new monomers and series of products in the PBO fiber industry chain starting from basic organic chemical raw materials, see formula (6), presenting a strong international competitive advantage.

However, there are still two major issues that need to be broken through:

1) Complicated manufacturing process, low production capacity, high price and limited application expansion

Although the process of using formula (5) to prepare PBO fiber has the absolute advantages of simplicity, high efficiency and high productivity, ABAA is prepared according to formula (6). In addition to MNB as a raw material to prepare ABAA technology, it also includes MNB with resorcinol The dinitration of (RSC) is 4,6-dinitroresorcinol (DNR), hydrazine hydrate is selectively reduced to salt as the patented product ANRHCl, and it is condensed with MTA to synthesize MNB in situ and other complicated processes. As a result, the price is higher, and the price of the prepared PBO fiber is not greatly reduced. It can only be used for special occasions in the defense and military industry, and cannot meet the urgent needs of high cost-effective applications in the industrial and civilian fields.

Therefore, the problem of low cost of monomers and fibers still needs to be solved. In comparison, the composite salt monomer is preferred. First, it can be prepared in a shorter reaction step, and secondly, it can be used to prepare fibers. It can also avoid the high temperature corrosion of HCl gas, achieve equivalent polymerization, and is easy to industrialize. The effect is also similar to the preparation of fibers from AB-type monomers, but it is necessary to avoid the additional introduction of ^{low-valent metal ions Sn 2+} and Fe ^{2+ while solving the key problem of the stability of its composite salt monomers (such as TDH).} In order to realize the recovery and recycling of the polymerization medium PPA, the process is clean and circular economy.

2) Lack of composite, light resistance and compression performance and improvement caused by the molecular structure of PBO itself

The PBO fiber exhibits three excellent properties of stretching, heat resistance and impact resistance, which are the best of organic fibers, mainly derived from its own rigid rod-shaped macromolecular structure and the highly ordered orientation structure obtained by liquid crystal spinning. However, due to the lack of polar groups in the molecular structure of PBO, the absence of any interaction bonds between molecular chains, and the very smooth surface of the fiber, the composite, axial compression, and ultraviolet light resistance are poor, which greatly restricts the directness of PBO fiber. The application in the field of advanced composite materials is only suitable for applications where it is reinforced and not in direct contact with the environment. If it is used in composite materials (bullet-proof armor, rocket and engine insulation materials), surface modification treatment is required: there are methods such as acid treatment, coupling agent treatment, plasma treatment and corona treatment to improve the surface adhesion of PBO fibers. Modification technology of bonding performance; there are also cross-linking methods with added substances, ceramic coating methods, multi-dimensional PBO materials and single-wall carbon nanotube (SWCNT) polymerization methods to improve the interaction between microfibers to improve the compression resistance of PBO fibers The performance improvement research shows the negative effects of fiber damage, degradation of the original mechanical properties, complex use, and higher prices. There is an urgent need for the research and support of PBO modification technology, especially the modification of the molecular structure, which can avoid the modification of the fiber after the fiber is made first, and the performance decline. Therefore, it enhances the interaction between the PBO macromolecular chains, improves the fiber axial compressive strength and the stability of ultraviolet light resistance, and improves the interface bonding performance between the fiber material and the resin matrix. It has become the PBO fiber that can be used directly as a reinforcing material. The key to the field of advanced composite materials.

Summary of the invention

The primary purpose of the present invention is to propose a class of multi-mixed composite salt monomers with excellent self-antioxidant stability. One component contained in this type of monomer has the dual function of being both an AA monomer and an organic antioxidant. .

The second object of the present invention is to provide a simple, effective, and low-cost method for preparing multi-mixed composite salt monomers, and the prepared monomers are characterized by low amounts of low-valent metal ions.

The third object of the present invention is to provide the application of the multi-mixed composite salt monomer in the preparation of multi-element polybenzodiazole liquid crystal polymer, which has no corrosive gas removal process, short polymerization time, high productivity, and easy Industrialization and other characteristics.

The fourth object of the present invention is to provide a multi-element polybenzodiazole liquid crystal polymer prepared by the self-condensation of the multi-mixed complex salt monomer.

The fifth object of the present invention is to provide the application of the multi-mixed composite salt monomer in the preparation of multi-element polybenzodiazole liquid crystal polymer fibers.

The sixth object of the present invention is to provide the multi-element polybenzodiazole liquid crystal polymer fiber.

The purpose of the present invention is achieved through the following technical solutions:

On the one hand, the present invention provides a type of mixed compound salt monomers represented by formula I, formula II or formula III. The mixed compound salt monomers contain an equal number of carboxyl groups and amino groups, and all carboxyl groups are equivalent to the same number. The number of amino groups is formed by carboxylic amine salt ionic bond to form a multi-mixed complex salt; among them, the structure shown in formula I is a four-mixed complex salt monomer, and its molecule consists of two AA monomers (n+m, the number of molecules is n, m ) And two paired BB monomers (n+m, the number of molecules is about n, m) are formed by carboxyamine salt ionic bonds (the structure of the four-mixed double salt monomer can also be represented by formula I', the present invention is For convenience, the following are represented by formula I); the structure shown in formula II or formula III is a three-mixed composite salt monomer, consisting of two AA monomers (n+m, the number of molecules is n, m) and one BB monomer (total number of molecules n+m) is formed by carboxyamine salt ionic bond:

In the formula: n and m are natural numbers, which respectively represent the number of molecules of each AA monomer and BB monomer in the composition of the mixed compound salt monomer;

m and n meet the following conditions: m/(m+n) = 0.005-0.50 (preferably 0.01-0.50);

X represents O atom or S atom;

Ar ₁ and Ar ₂ are each independently selected from the following tetravalent organic groups connected with two hydroxyl groups or mercapto groups and two amino groups or four amino groups on the aromatic ring:

Ar is selected from one of the following divalent organic groups connected to two carboxylates in the para position of the aromatic ring:

Ar _{0 is} selected from the following divalent organic groups with two carboxylates connected to the para position of the aromatic ring:

The multi-mixed composite salt monomer of the present invention contains a component ^- OOC-Ar ₀ -COO ^- that is

(DHTA), it is not only a modified AA monomer, which can improve the composite performance of the material; it can also be used as an organic antioxidant. The hydroxy and amino groups forming the benzodiazole exhibit their stability unchanged) without the need to add the low-valent metal ion antioxidant Sn ²⁺ . by

Determined by the antioxidant mechanism of the present invention, during the storage process of the multi-mixed composite salt monomer, the

At least partly due to oxidation

(Ie p- benzoquinone 2,5 dicarboxylic acid DQDCA), because p- benzoquinone 2,5 dicarboxylic acid (DQDCA) can also polymerize with BB monomers (such as DAR) to form a rigid benzodiazole structure, so it can Ensure that the polymerization performance of the multi-mixed compound salt monomer remains unchanged.

When the multi-mixed composite salt monomer is a three-mixed composite salt monomer, preferably m/(m+n)=0.005-0.025 (more preferably m/(m+n)=0.005-0.01), at this time 2 ,5-Dihydroxyterephthalic acid (DHTA) has been able to provide sufficient antioxidant effect, and the introduction of 2,5-dihydroxyterephthalic acid (DHTA) can not only improve the composite performance of the material, but also use the monomer The prepared polymer has improved heat resistance. Generally speaking, although the introduction of dihydroxy groups can improve the composite performance of polymer materials, it will correspondingly weaken the heat resistance of polymer materials. However, the present invention unexpectedly found that the control of m/(m+n) = 0.005-0.025, The heat resistance of the copolymer obtained by the self-condensation of the three-mixed complex salt monomer is higher than that of the homopolymer obtained by the self-condensation of the two-mixed complex salt monomer without 2,5-dihydroxyterephthalic acid (DHTA). For example, m/(m+n) = 0.005-0.025 of the binary polybenzodiazole liquid crystal polymer DHPBO-co-PBO obtained by the self-condensation of the three-mixed complex salt monomer (DAR)-and-(nTPA/mDHTA) The heat resistance is higher than that of the PBO obtained by the self-condensation of the two mixed compound salt monomer (nDAR)-and-(nTPA). In addition, the present invention also found that the heat resistance of the binary copolymer obtained by the self-condensation of the three mixed compound salt monomers is also higher than that obtained by the copolymerization of the corresponding two mixed compound salt monomers with the same m value and the same molecular chain. The heat resistance of the binary copolymers, such as the three-mixed compound salt monomer (DAR)-and-(nHTA/mDHTA) self-condensation, the heat resistance of the binary copolymer DHPBO-co-HPBO is higher than that of two The heat resistance of the binary copolymer DHPBO-co-HPBO with the same m value obtained by copolymerization of two mixed compound salt monomers.

When the multi-mixed composite salt monomer is a four-mixed composite salt monomer, m/(m+n) is preferably 0.005-0.20, more preferably 0.01-0.20, and in this case, 2,5-dihydroxyterephthalene Formic acid (DHTA) not only provides sufficient anti-oxidation and stability, but also improves the composite properties of the material.

It should be pointed out that the multi-mixed composite salt monomer of the present invention, when the raw material for its preparation contains

When the raw material itself is easy to oxidize, it usually adds low-valent metal ion Sn ²⁺ as an antioxidant ^{during storage (Sn 2+} content is generally between 2500-3500 ppm), so the prepared multi-mix composite salt monomer ^{Some Sn 2+} may be brought in because of the raw materials. ^{Preferably, the Sn 2+} in the multi-mixed composite salt monomer is controlled to be 200 ppm or less.

The present invention selects the multiple mixed compound salt monomers shown in formula I, II, III and IV according to the influence law of structure and group on material properties (hydroxyl, methyl, imidazole), abbreviation: m/(n+m) Functional group (and/or aromatic ring tetraamine) PBO multi-mixed composite salt. Among them: Formula I (or Formula I') is a four-mixed compound salt monomer, abbreviated as n (BB monomer/AA monomer)-and-m (BB monomer/AA monomer), composed of two AA monomers And two BB monomers; formula II and III are three mixed compound salt monomers, abbreviation: formula II, III: (BB monomer)-and-(nAA monomer/mAA monomer); formula IV: (AA Monomer)-and-(n BB monomer/m BB monomer), prepared from one BB monomer and two AA monomers and from one AA monomer and two BB monomers. further,

Choose from one of the following structures:

further,

Choose from one of the following structures:

Further, ^- OOC-Ar-COO ^- is selected from one of the following structures:

Furthermore, the four-mixed composite salt monomer compound represented by formula I is preferably one of the following:

Still further, m/(n+m)=0.01-0.20 in the four-mix composite salt monomer compound represented by formula I.

Furthermore, the three-mixed complex salt monomer represented by formula II is preferably one of the following:

Still further, in the three-mixed complex salt monomer represented by formula II, m/(n+m)=0.005-0.025.

In the present invention, it is particularly preferred that the three-mixed complex salt monomer represented by formula II is one of the following: (DAR)-and-(nTPA/mDHTA), (DAR)-and-(nHTA/mDHTA), where m/(n+ m) = 0.005-0.01. In a specific embodiment, both (DAR)-and-(nHTA/mDHTA) with m/(n+m)=0.005 and (DAR)-and-(nTPA/mDHTA) with m/(n+m)=0.01 Obtained particularly good technical effects.

Furthermore, the three-mixed complex salt monomer represented by formula III is preferably one of the following:

Still further, m/(n+m)=0.005 to 0.025 in the monomer of the three mixed complex salt represented by formula III.

In the second aspect, the present invention provides a method for preparing a multi-mixed composite salt monomer. The preparation method is prepared by neutralizing and compounding AA monomer and BB monomer hydrochloride in an alkaline oxygen-free aqueous solution. The AA monomer is a dibasic acid in the para position of the aromatic ring Ar or Ar ₀ , respectively selected from the AA monomers represented by formula IX and formula IX'; the BB monomer hydrochloride is selected from the formula X And BB monomer hydrochloride represented by formula X', and the combination of AA monomer and BB monomer hydrochloride is one of the following:

1) One type of IX+one type of IX’+one type of X+one type of X’;

2) One type of IX+one type of IX’+one type of X;

3) One type of IX+one type of IX’+one type of X’;

The feeding ratio of the AA monomer and the BB monomer hydrochloride satisfies the following conditions: the molar ratio of the AA monomer represented by the formula IX' to the AA monomer represented by the formula IX is m:n and/or the formula X' The molar ratio of the BB monomer hydrochloride shown by the formula X to the BB monomer hydrochloride shown by the formula X is m:n;

In the formula: X, Ar, Ar ₀ , Ar ₁ , and Ar _{2 are} as defined above, and x and y are the number of HCl molecules in the BB monomer hydrochloride, respectively.

In the preparation method of the multi-mixed composite salt monomer of the present invention, the Sn content in the multi-mixed composite salt monomer is controlled to be less than 200 ppm by controlling the amount of solvent water. Specifically, the amount of solvent water can be estimated according to the following methods: First, determine the yield value of the composite salt product and the moisture content value of the multi-mixed composite salt monomer wet product based on experience. Due to the composition of the multi-mixed composite salt monomer wet product It is a multi-mix composite salt monomer, water and Sn, so first determine the Sn content value according to the Sn content requirement of the multi-mix composite salt monomer, and then according to the determined Sn content value and the moisture content of the wet product of the multi-mix composite salt monomer ^{It is worthwhile to find out the Sn 2+} concentration (denoted as P _Sn (ppm)) of the Sn-containing aqueous solution in the wet product of the mixed compound salt monomer, because the terephthalic acid in the mixed compound salt monomer will make the Sn ^{2 in the aqueous solution + Is} enriched on the surface of the composite salt, so based on experience, P _Sn /8 is used as the Sn ²⁺ concentration in the reaction system, which is used as the basis for configuring the reaction system.

Further, the AA monomer represented by formula IX is preferably one of the following:

Further, the BB monomer hydrochloride represented by formula X is preferably one of the following:

Further, the BB monomer hydrochloride represented by formula X'is preferably one of the following:

The preferred reaction is:

Further, the preparation method is prepared according to the following steps:

1) Dissolve AA monomer in a deoxygenated aqueous solution of a certain equivalent of alkaline substance to obtain a deoxygenated aqueous solution of AA monomer diformate;

2) Under nitrogen protection and stirring, dissolve a certain amount of BB monomer hydrochloride in deoxygenated water to form an aqueous solution, and slowly add it to the deoxygenated aqueous solution of AA monomer diformate at 60-70°C for neutralization and compounding reaction. Formation of multiple mixed compound salt monomer precipitation;

3) Stir and cool to room temperature under nitrogen protection, filter, wash with oxygen-free water, and vacuum dry to obtain the multi-mixed composite salt monomer.

Furthermore, the alkaline substance described in step 1) is one or a combination _{of NH 4} OH, NaOH, KOH, NaHCO ₃ , KHCO ₃ , Na ₂ CO ₃ , and K ₂ CO _{3, and NH 4 OH, NaOH, KOH, NaHCO 3, KHCO 3, Na 2 CO 3, and K 2 CO 3 4} OH, NaOH, and Na ₂ CO ₃ are preferred. The said certain equivalent means that the equivalent of the alkaline substance is 0.99-1.00 times the total equivalent of HCl in the BB monomer hydrochloride.

Furthermore, in step 2), the said certain amount means that the molar ratio of BB monomer hydrochloride to AA monomer is 0.99-1.04; preferably 1.01-1.03.

Furthermore, the conditions of vacuum drying in step 3) are: vacuum drying at 70° C. for 5-7 hours.

In the third aspect, the present invention provides the application of the multi-mixed composite salt monomer in the preparation of multi-component polybenzodiazole liquid crystal polymer by self-condensation, and the application is: the multi-mixture shown in formula I, formula II or formula III The mixed compound salt monomer _{is self-condensed in the P 2} O ₅ -PPA system to prepare the corresponding multi-element polybenzodiazole liquid crystal polymer represented by formula V, formula VI or formula VII;

In the formula, n, m, X, Ar ₁ , Ar ₂ , Ar, and Ar ₀ are defined as above, and k is a random variable, 1≤k≤m-1.

In the application, the number of chain links n, m and their ratios are determined in the preparation of the multi-mixed composite salt monomer; where m is the number of molecules of the organic antioxidant and the monomer for modification, which can be based on different performance requirements , So that the ratio of the total number of n+m molecules is selected within a certain range, k is a random variable when preparing the polymer, and 1≤k≤m-1.

Further, based on the total mass of polyphosphoric acid, phosphorus pentoxide and multi-mixed complex salt monomers being 100%, the mass fraction of multi-mixing complex salt monomers is 15-25%; based on P ₂ O ₅ and polyphosphoric acid , The mass fraction of phosphorus pentoxide is 86.5% to 88%.

Further, the application specifically includes the following steps:

_{1) Add quantitative P 2} O ₅ to polyphosphoric acid (PPA) in the glass polymerization reaction column to _{make the P 2} O ₅ reaction basically dissolve (persons skilled in the art can use stirring, heating, etc. to promote the dissolution according to actual needs. ), slowly add the selected multi-mixed compound salt monomer to form a PPA polymerization reaction system; in the PPA polymerization reaction system, the mass amount of the multi-mixed compound salt monomer accounts for polyphosphoric acid, P ₂ O ₅ and multi-mixed 15-25% of the total mass consumption of the composite salt monomer, and the mass consumption of P ₂ O ₅ accounts for 86.5-88.0% of the total mass consumption of polyphosphoric acid and P ₂ O _5;

2) _{Under the protection of N 2} , the PPA polymerization reaction system is stirred and dissolved at 100-130°C for 50-90 minutes, and then slowly heated to 145-170°C for 0.5-2h at a stirring rate of 300-400r/min. At this time, the whole body appears. Fluorescence, and then program the temperature to 170-200°C at a rate of 5-15°C/hour (liquid crystals and filaments appear successively during the process), and stir until the speed drops below 200r/min to complete the polymerization reaction. Stir and cool to 120～150℃, the PPA liquid crystal stock solution of the corresponding multi-element polybenzodiazole liquid crystal polymer can be obtained.

In the present invention, in order to study the performance of the polybenzodiazole liquid crystal polymer prepared, it is generally made into monofilament fiber, and its intrinsic viscosity (molecular weight), IR (fiber characterization), heat resistance temperature (heat Re-analysis). Therefore, the application generally includes step 3): manually drawing the liquid crystal stock solution of the multi-element polybenzodiazole liquid crystal polymer, coagulating, washing with water, and vacuum drying to prepare monofilament fibers. It is further preferred that the step 3) is operated as follows: control the temperature of the material to be between 120 and 150°C, perform manual and continuous drawing from the PPA liquid crystal stock solution of the prepared multi-element liquid crystal polymer, and pull the drawn dry silk into the water After coagulation, washing with hot water for several times to neutrality, and vacuum drying (preferably vacuum drying at 110° C. for 3-5 hours), monofilament fibers of multi-element polybenzodiazole liquid crystal polymer are obtained.

In the fourth aspect, the present invention provides a type of multi-element polybenzodiazole liquid crystal polymer (abbreviation: m/(n+ m) Functional group (and/or aromatic cyclic imidazole) modified PBO); the intrinsic viscosity of the multi-element polybenzodiazole liquid crystal polymer is 8-40dL/g;

In the formula, n, m, X, Ar ₁ , Ar ₂ , Ar, and Ar ₀ are defined as above, and k is a random variable, 1≤k≤m-1.

The present invention selects the multi-element polybenzodiazole liquid crystal polymer whose properties meet the requirements according to the influence law of structure and group on material properties (hydroxyl, methyl, imidazole). Wherein: the structure of formula V is a quaternary liquid crystal polymer, abbreviated as (R)PBX ₁ -co-(R)PBX ₂ , prepared from the tetramixed compound salt monomer represented by formula I or I'. The structures of formula VI and VII are binary liquid crystal polymers, and the abbreviations of formula VI and VII are R ₁ PBX-co-R ₂ PBX, which are respectively prepared from the three mixed compound salt monomers represented by formula II or formula III. Among them: Formula VI and Formula VII can be _{replaced by simplified abbreviations R 1} -R ₂ -(R)PBO and S-(R ₁ )-(R)PBO: R, R ₁ , R ₂ are the abbreviations of functional groups for modification ( Monohydroxy H, dihydroxy DH, methyl M); S, BX, BX ₁ , BX ₂ are the structural abbreviations of benzoxazole (benzodioxazole BO, benzodiimidazole BI, pyridine diimidazole PI, biphenyl Diimidazole BPI, benzimidazole oxazole BIO, biphenyl dioxazole BPO).

Specifically, the structure of formula V is a quaternary liquid crystal polymer, abbreviated as (R)PBX ₁ -co-(R)PBX ₂ , which can contain both oxazole (X=O) and imidazole ring, or thiazole (X=S) With the imidazole ring, it is based on the molecular structure of poly-p-phenylene benzodioxazole (PBO) or poly-p-phenylene benzodithiazole (PBT). According to the addition of different components, the liquid crystal polymer has different performance requirements. Polymer modification is a polymer composed of four chain links: _{PBX 1} , RPBX ₁ , PBX ₂ , and RPBX _2. Among them: the role of the introduced imidazole ring combined with the hydroxyl group can improve the light stability composite and axial compressive performance of the polymer material. The quaternary polymer structure shown in formula V is preferably one of the following:

The structures of formula VI and formula VII are both binary liquid crystal polymers, which are a kind of polymer composed of two kinds of chain segments, and are prepared from three mixed compound salt monomers. among them:

(1) The structure of formula VI is based on the molecular structure of poly-p-phenylene benzodioxazole PBO (X=O) or poly-p-phenylene benzodithiazole PBT (X=S), which is modified by hydroxyl groups to improve polymerization The light stability and composite properties of the material can be modified by methyl to improve the fiber-forming processing performance of the polymer. The structure of the binary liquid crystal polymer shown in formula VI is preferably one of the following:

It is worth mentioning that when m = 0.005-0.025, the introduction of modified chain links not only improves the light stability and composite performance of the polymer material brought about by the hydroxyl modification, but also unexpectedly improves the polymer material. The heat resistance.

(2) The structure of formula VII is based on the molecular structure of polyparaphenylene benzimidazole (PBI), modified by hydroxyl groups, which can greatly improve the light stability and composite compressive performance of the polymer material, as shown in formula VII The binary liquid crystal polymer structure is preferably one of the following:

The multi-element polybenzodiazole liquid crystal polymers of the structures represented by the formula V, the formula VI and the formula VII are respectively obtained by the self-condensation of the multi-mixed composite salt described in the formula I, the formula II and the formula III, and the self-condensation For details of the operation of the reaction, refer to the third aspect "Application of the multi-mixed complex salt monomer in the preparation of multi-component polybenzodiazole liquid crystal polymer by self-condensation", which will not be repeated here.

In the fifth aspect, the present invention provides the application of the multi-mixed composite salt monomer in the preparation of multi-component polybenzodiazole liquid crystal polymer fibers, and the application includes:

1) Using polyphosphoric acid (PPA) as the medium and phosphorus pentoxide as the dehydrating agent, the self-condensation of the multi-mixed composite salt monomers represented by formula I, formula II or formula III is carried out under the protection of nitrogen to obtain the formula The liquid crystal spinning dope of the multi-element polybenzodiazole liquid crystal polymer shown in V, VI or VII;

2) The liquid crystal spinning dope of the multi-element polybenzodiazole liquid crystal polymer adopts the liquid crystal spinning technology of the dry-jet wet method to prepare multi-element liquid crystal polymer fibers, and the fibers are nascent (AS) multifilament composite fibers or high modulus fibers. (HM) Multifilament composite fiber.

The step 1) includes pre-polymerization and reaction extrusion polymerization steps in a screw machine to obtain the liquid crystal spinning dope of the multi-element polybenzodiazole liquid crystal copolymer. Said step 2) includes high-pressure jet extrusion of dry filaments, stretching in an air bath, coagulation in a coagulation bath, alkaline washing, water washing and drying steps to obtain the primary (AS) multifilament composite of the multi-element polybenzodiazole liquid crystal polymer Fiber, the nascent (AS) multifilament composite fiber is heat-treated to obtain a high modulus (HM) multifilament composite fiber. (See attached figure 16)

Further, the application specifically includes the following steps:

1) Pre-polymerization: Add a certain concentration of PPA and a quantitative amount of P ₂ O ₅ in the pre-polymerization pressure vessel to form a PPA containing 86.5-88% P ₂ O _5. Seal the polymerization vessel and stir it evenly. Under protection, add the selected multi-mixed compound salt monomers in sequence within 5-15 minutes, and control the feeding temperature below 90°C to form a polymerization reaction system with a multi-mixed compound salt monomer mass concentration of 15-25% (calculated value). After replacing the air with nitrogen repeatedly, the prepolymerization is completed by slowly raising the temperature from 90℃ to 160℃ within 0.5～2h under the protection of nitrogen (prepolymer η is about 10-15dL/g), stop stirring, and remove the prepolymerization press Kettle barrel

Reactive extrusion polymerization in the screw machine: The cylinder containing the prepolymer liquid crystal liquid is quickly transferred to the pressing device, and the prepolymer material is sequentially pressed into the series twin screw machine-1 (160℃～190) using the feeding device. ℃ four-stage temperature control zone, successively four zones temperature control is 160℃, 175℃, 190℃, 170℃) and twin screw machine-2 (170～180℃ four-stage temperature control zone, successive four zones temperature control is 170℃ , 175℃, 180℃, 180℃), control the appropriate screw speed to make the total residence time of the material reaction, extrusion and polymerization of the two tandem screw machines 50-70min, and then strictly degas at 160-170℃ by the degasser , After filtering by the high-viscosity filter, the liquid crystal spinning dope (the total mass concentration of the liquid crystal polymer is 10-18%) as the corresponding multi-element polybenzodiazole liquid crystal polymer enters the spinning section;

2) The liquid crystal spinning element is hydraulically inserted into the spinneret which has been preheated to 160～180℃ in the spinning machine, and the feed amount is precisely controlled by the spinning metering pump. The temperature is 5～20MPa and 160-180℃. The spinneret ejects the dry tow at high pressure, and the dry tow is rapidly stretched in a hot air bath at 40～60℃ (the stretching ratio is controlled by the rotation speed of the tractor), and then enters the coagulation bath in which the coagulation liquid is an aqueous phosphoric acid solution for coagulation and Stretching to make the fiber compact, and then through the pulling and preliminary washing of the tractor with tension isolation and washing, and enter the alkali washing tank under the traction of the double-roll washing machine to remove residual phosphoric acid, and finally water through the double-roll washing machine After drying at 120～150℃ in a double-roll steam dryer, it is wound by a winding (reel) machine at a certain linear speed (50-200m/min) to obtain a polybenzodiazole liquid crystal polymer. The nascent (AS) multifilament composite fiber.

Furthermore, the preparation process of the multifilament fiber further includes the following step 3):

3) The nascent-AS multifilament fiber of the prepared multi-element polybenzodiazole liquid crystal polymer is directly in the fiber heat treatment device and passed through the yarn machine under a given tension (about 10% fiber tensile strength). Heat treatment in a drying tunnel at 520～600℃ for 10～30 seconds in a nitrogen atmosphere, and obtain the high modulus (HM) multifilament fiber of polybenzodiazole liquid crystal polymer by the winding machine at a winding speed of 30～50m/min. .

Preferably, in the above step 2) of the present invention, the coagulation liquid adopts a multi-stage gradient coagulation bath (see FIG. 18), and specifically adopts the operation of n-stage coagulation baths in series and the fibers and the coagulation liquid in reverse operation:

The multi-stage gradient coagulation bath is composed of n coagulation baths in series, the value of n is 3-5, and the setting height from coagulation bath 1 to coagulation bath n is gradually raised, and each coagulation bath is set There is an overflow port, so that the coagulation liquid in the coagulation bath n can overflow into the adjacent coagulation bath n-1, and the coagulation liquid in the coagulation bath n-1 can overflow into the coagulation bath n-2, and so on; The coagulation liquid in each coagulation bath is an aqueous phosphoric acid solution. The concentration of the phosphoric acid aqueous solution in the coagulation bath is represented by C, and the _{concentration decreases from C 1} to C _n ; the temperature of the coagulation bath for setting the coagulation bath is represented by T, from T ₁ to T _n The temperature of the coagulation liquid is reduced in sequence; during the coagulation process, the high-pressure sprayed and stretched dry tow is successively passed through the coagulation bath 1, the coagulation bath 2 until the coagulation bath n, and the coagulation bath n is continuously refilled with water to make the coagulation bath The coagulation liquid in n overflows into the coagulation bath n-1 to dilute the coagulation liquid in the coagulation bath n-1, and solves the problem of the concentration of the coagulation liquid in the coagulation bath n-1 caused by the spread of the solvent in the fiber, so as to maintain continuous During operation, the concentration of phosphoric acid in coagulation bath n-1 is constant; in the same way, other adjacent coagulation baths also maintain a constant concentration of phosphoric acid in the coagulation bath through the same process, and finally a higher concentration of phosphoric acid aqueous solution is discharged at the overflow of coagulation bath 1. The obtained higher concentration phosphoric acid aqueous solution is used for the recovery of phosphoric acid, the regeneration and recycling of PPA.

Those skilled in the art can understand that during the coagulation operation, the coagulation liquid concentration C and the coagulation liquid temperature T in each coagulation bath are difficult to be fixed, so the maintenance of "constant concentration" in the present invention does not mean The concentration must be maintained at a fixed value, and it is usually maintained within a certain range, and the temperature T is the same.

Preferably, the coagulation liquid in the present invention adopts a 4-stage gradient coagulation bath, that is, n=4. Preferably, the concentration of the coagulation liquid in the coagulation bath 1, the coagulation bath 2, the coagulation bath 3, and the coagulation bath 4 are maintained at 22-28 wt%, 8-12 wt%, 3-5 wt%, and 1-1.5 wt%, respectively. In the present invention, it is preferred that T ₁ =48-56°C, T ₂ =38-46°C, T ₃ =28-36°C, and T ₄ =18-26°C.

The present invention adopts the above-mentioned multi-stage gradient coagulation bath, which has multiple technical effects: while improving the density of the fiber and reducing the voids in the cross section, the fiber can be further stretched, and the phosphoric acid in the wet fiber can be washed to the greatest extent, and it is convenient After the higher concentration of C ₁ phosphoric acid coagulation liquid is recovered, polyphosphoric acid is prepared and recycled.

In a sixth aspect, the present invention provides a multi-element polybenzodiazole liquid crystal polymer fiber prepared according to the application described in the fifth aspect.

The multi-mixed composite salt monomer prepared by the invention has excellent self-oxidation stability and high yield. The intrinsic viscosity of the multi-element polybenzodiazole liquid crystal polymer prepared by the self-condensation of multiple mixed compound salt monomers is 8-40dL/g. The diameter of the monofilament fiber is 15-50um; the properties of the nascent multifilament fiber are: the diameter of a single fiber is 12-16um, the fineness is 2.6-3.0dtex, the moisture content is 5-7%, the tensile strength is 3.4-3.7GPa, and the modulus is 130 -160GPa; high modulus multifilament fiber (HM) performance: single fiber diameter 12-16um, fineness 2.6-3.0dtex, tensile strength 3.5-3.6GPa, modulus 200-210GPa.

Compared with the existing PBO corresponding monomers (AB type, AA-BB monomers and composite salt monomers) and the molecular structure of the liquid crystal polymer, the present invention has the following beneficial effects:

1) Compared with the two mixed compound salt monomers (such as DAR/TPA, TAP/DHTA) used in a single polymer (PBO, PIPD), the multi-mix compound salt monomer provided by the present invention has excellent self-antioxidant stability Characteristic, it is more convenient and effective when used to prepare multi-element polybenzodiazole liquid crystal polymer, and can produce good environmental protection and economic benefits.

Specifically, the one-component DHTA contained in the multi-mixed compound salt monomer is a modified AA monomer. The hydroxyl group contained in it can improve the composite performance of the material and control the DHTA in the three-mixed compound salt monomer. The addition amount of PBO can unexpectedly improve the heat resistance of the material within a certain range. Therefore, according to the performance, price and modification requirements of the PBO material, the appropriate AA monomer and BB monomer hydrochloride can be selected to prepare the three The combination of mixed compound salt and tetra-mix compound salt can easily and effectively prepare binary or quaternary polybenzodiazole liquid crystal polymer with required properties and its high performance by self-mixing and polycondensation with only one multi-mix compound salt monomer. Performance composite fiber; and, also unexpectedly, the heat resistance of the binary copolymer prepared by the three-mixed compound salt monomer is better than that of the same m and molecular chain links obtained by the copolymerization of two two-mixed compound salt monomers. The heat resistance of the same binary copolymer.

More importantly, DHTA is used as an organic antioxidant in the multi-mix composite salt, which effectively solves the antioxidant problem of the monomer storage of the composite salt, without the need to add low-valent metal ions Sn ²⁺ , so that the multi-mix composite The Sn content in the salt monomer is significantly reduced, and the reduction of the Sn content can significantly increase the number of PPA recycling cycles during the preparation of the polybenzodiazole liquid crystal polymer and its high-performance composite fiber, achieving both clean production and recycling economy Effect.

2) The preparation technology of the multi-mix composite salt monomer developed by the present invention: In addition to the selection of deoxygenated water and nitrogen protection, the raw materials are easy to obtain, the preparation process is conventional, and the total metal ions total Sn is less than 200ppm and no additional Sn ^{2 is required. + And} other inorganic antioxidant polymer grade monomers, showing the advantage of low cost.

3) The present invention uses multi-mixed composite salt monomers as raw materials to prepare multi-element polybenzodiazole liquid crystal polymers and their high-performance fibers. The polymerization process does not require removal of HCl, no interference of strong corrosive gases, and no additional addition of SnCl ₂ and other anti-corrosion products. Oxygen agent, short polymerization time, high polymer concentration, conventional equipment, high production capacity, convenient operation and easy production of raw materials. In addition to the same characteristics as AB monomer polymerization and spinning, the application of multi-mixed compound salt monomers is more Presents the advantages of more convenient implementation, more environmentally friendly and economical.

On the one hand, the multi-component liquid crystal polymer is prepared by self-cocondensation of only one multi-mixed composite salt monomer, and is applied to the preparation of high-performance PBO fiber and modified PBO composite fiber. It has the characteristics of convenient industrialization and is compared with The copolymerization of a plurality of two mixed compound salt monomers to prepare a multi-element liquid crystal polymer can also improve the heat resistance of the polymer.

On the other hand, because the multi-mixed composite salt monomer has good anti-oxidation performance and no additional low-valent metal ion Sn ^{2+ is required} , the Sn content in the multi-mixed composite salt monomer is significantly reduced, and the Sn content is reduced. It can significantly increase the number of PPA recycling cycles in the preparation process of the polybenzodiazole liquid crystal polymer and its high-performance composite fiber, so as to achieve the effect of achieving clean production and generating circular economy. In addition, in the process of preparing high-performance composite fibers by dry-jet wet spinning, a multi-stage gradient coagulation bath is used to coagulate and stretch the fibers, which has multiple technical effects: while improving fiber density and reducing cross-sectional voids, The fiber can be further stretched, and the phosphoric acid in the wet fiber can be washed away to the greatest extent, and it is convenient for the recovery of the phosphoric acid in the phosphoric acid coagulation liquid with a higher concentration (22-28wt%) to produce polyphosphoric acid and recycling. Realize a circular economy.

4) The multi-element polybenzodiazole liquid crystal polymer obtained by the self-condensation of multi-mixed composite salt monomers of the present invention is a new class of very useful materials, and its structure and performance have particularities:

① The structure of the multi-element polybenzodiazole liquid crystal polymer prepared by the present invention has polymer alloy properties, each AA monomer can be matched with each BB monomer, and can exhibit additional performance; different types can be conveniently added The components of the liquid crystal polymer are modified with different performance requirements. For example, two AA monomers with molecular numbers m and n and two paired BB monomers (m, n) are neutralized and compounded to form a quaternary polymer. Except for paired n and m compound In addition to the original properties of the original molecular chain of the polymer formed by the salt (but the two molecular chains of n and m both reduce the k/(n+m) chain), there are also random additional molecular chains that increase cross-matching (For example, the two k/(n+m) links in formula I) correspond to the additional properties of polymer fibers.

② The performance of the multi-element polybenzodiazole liquid crystal polymer and its composite fiber prepared by the multi-mixed composite salt monomer of the present invention is higher than that of the block copolymer and its composite fiber prepared from the same multi-component component, and can avoid The problem that certain single polymers cannot be processed into fibers.

③ The multi-element polybenzodiazole liquid crystal polymer and its fiber material prepared by the present invention can have the following performance characteristics:

(a) The present invention introduces DHTA to modify the polybenzodiazole liquid crystal polymer. On the one hand, it improves the composite performance of the polymer. On the other hand, it controls the addition of DHTA in the three-mix composite salt monomer to control the binary The value of m in the polymer can unexpectedly improve the heat resistance of the material within a certain range. In addition, experiments have shown that the heat resistance of the binary copolymer prepared by the three-mixed compound salt monomer is better than that of the binary copolymer with the same m and the same molecular chain obtained by the copolymerization of two two-mixed compound salt monomers. Thermal performance.

(b) Partial introduction of hydroxyl OH polar groups on the phenylene Ar of the main chain can effectively solve the problem of smooth PBO fiber surface, greatly improve the interface bonding performance with resin, and the composite of polymer and fiber. And light resistance, while improving the flexural modulus of the fiber; the methyl CH _{3 introduced in the aromatic ring Ar 1} or Ar ₂ of the benzoxazole, the polymer molecular chain is thermally cross-linked to form a partial covalent bond connection, which can be Improve the axial compressive performance of polymer fibers;

(c) Partial introduction of imidazole ring in the main chain of oxazole can improve the light stability of the polymer material (the structure of the imidazole ring is very stable under ultraviolet light). Imidazole also forms a hydrogen bond network with the hydroxyl OH introduced in Ar after the polymer is formed to improve the axial compressive performance of the polymer fiber; but the introduction of imidazole and hydroxyl will reduce the heat resistance; replace Ar with a biphenyl ring _{The benzene ring in 1} and Ar ₂ can increase the heat resistance temperature of the polymer.

(d) Select the mixed compound salt monomer prepared by introducing a hydroxyl group on the benzene ring of the aromatic ring diacid and replacing the two hydroxyl groups with two amino groups in the DAR to introduce imidazole, so that it can be used in the polymer obtained by polymerization and spinning. And the fiber has good potential functions of compounding, compression resistance and light resistance. The introduction of methyl group in DAR has potential axial compression function.

(e) The multi-element polybenzodiazole liquid crystal polymer prepared by the present invention exhibits good spinnability in PPA solvent. For example, the preferred polybenzodiazole liquid crystal polymer HPBO-co-PBO, DHPBO-co-PBO (1% dihydroxy modified PBO) shows good spinnability in PPA solvent, and the liquid crystal spinning dope is processed into fibers. During the process, the mass concentration (calculated value) of the liquid crystal polymer can be as high as 14-16%. At the end of their polymerization, the polymer liquid crystal spinning dope can be directly applied to dry jet wet spinning to obtain the corresponding 5-50% monohydroxyl group without taking it out. High-performance composite fiber of modified PBO (HPBO-co-PBO) and 1% dihydroxy PBO fiber (1% DHPBO-co-PBO).

In summary, through the multi-mixed composite salt monomer and the preparation method of the present invention, and the self-polymerization of the multi-mixed composite salt monomer to prepare a multi-component polybenzodiazole liquid crystal polymer and the application of its fiber, it is possible to greatly reduce The production cost can also achieve the purpose of modification (such as improving the fiber's UV resistance and composite bonding performance, etc.). It is expected to replace PBO and M5 fibers to become a new generation of PBO fibers (referred to as Fyzolon high-performance fibers): Including polybenzoxazole-based PBO high-performance fiber FZ-PBO, polybenzimidazole-based PBI high-performance fiber FZ-PBI, polybenzimidazole and oxazole mixed PBIO high-performance fiber FZ- PBIO, which can be prepared from the multi-mixed composite salt monomer raw materials of the present invention, can be directly used in the field of advanced composite materials without surface treatment. The commercial production of a new generation of PBO high-performance fiber aramid Fyzolon is implemented to meet the requirements of aerospace There is an urgent need for the replacement of composite materials in high-tech fields such as aviation and national defense.

Description of the drawings

Figure 1 is the infrared spectrum of the 20% dihydroxy and phenyltetramine modified PBO four-mixed composite salt monomer n(DAR/TPA)-and-m(TAB/DHTA) prepared in Example 1 of the present invention.

Fig. 2 is an infrared spectrogram of a 20% (DH)PBI-co-(DH)PBO quaternary liquid crystal polymer monofilament composite fiber prepared in Example 1 of the present invention.

Figure 3 is a thermogravimetric analysis diagram of 20% dihydroxy and benzimidazole modified PBO monofilament composite fiber prepared in Example 1 of the present invention. (502℃)

Fig. 4 is an infrared spectrogram of the 20% dihydroxy and biphenyltetramine modified PBO four-mixed double salt monomer n(DAR/TPA)-and-m(TABP/DHTA) prepared in Example 2 of the present invention.

Fig. 5 is an infrared spectrum chart of a 20% (DH)PBPI-co-(DH)PBO quaternary liquid crystal polymer monofilament composite fiber prepared in Example 2 of the present invention.

Fig. 6 is a thermogravimetric analysis diagram of a 20% dihydroxy and bibenzimidazole modified PBO monofilament composite fiber prepared in Example 2 of the present invention. (560℃)

Fig. 7 is an infrared spectrum diagram of 1% dihydroxy modified PBO triple mixed double salt monomer (DAR)-and-(nTPA/mDHTA) prepared in Example 3 of the present invention.

Fig. 8 is an infrared spectrum diagram of a binary liquid crystal polymer 1% DHPBO-co-PBO monofilament composite fiber prepared in Example 3 (2) of the present invention.

Fig. 9 is a thermogravimetric analysis diagram (630°C) of the binary liquid crystal polymer 1% DHPBO-co-PBO monofilament composite fiber prepared in Example 3(2)-A) of the present invention.

Figure 10 is a thermogravimetric analysis graph (615°C) of 2.5% DHPBO-co-PBO monofilament composite fiber prepared in Example 3 (2) and Comparative Example 1-B) of the present invention.

Fig. 11 is a thermogravimetric analysis graph (468°C) of a binary liquid crystal polymer 50% DHPBO-co-PBO monofilament composite fiber prepared in Example 3 (2), Comparative Example 1-C) of the present invention.

Figure 12 is an infrared spectrum of 0.5% dihydroxy modified HPBO triple mixed double salt monomer (DAR)-and-(nHTA/mDHTA) prepared in Example 4 of the present invention.

Fig. 13 is an infrared spectrogram of 0.5% DHPBO-co-HPBO binary liquid crystal polymer monofilament composite fiber prepared in Example 4 of the present invention.

14 is a thermogravimetric analysis diagram of 0.5% dihydroxy-modified HPBO monofilament composite fiber prepared in Example 4 of the present invention. (606℃)

15 is a thermogravimetric analysis diagram of 0.5% dihydroxy-modified HPBO monofilament composite fiber prepared by copolymerization of two composite salt monomers (HD+DHD) in Example 4 and Comparative Example 2 of the present invention. (590℃)

Fig. 16 is a pilot-scale process flow chart of an embodiment in which multiple mixed composite salt monomers are used to prepare polybenzodiazole liquid crystal polymer multifilament fibers.

Figure 17 is a thermogravimetric analysis graph (617°C) of the 1% dihydroxy-modified PBO multifilament (241f) composite AS fiber prepared in Application Example 2 of the present invention.

Fig. 18 is a schematic diagram of the device and flow diagram of the multi-stage gradient coagulation bath used in the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the implementation of the present invention is not limited thereto.

Example 1 Preparation and application of four mixed compound salt monomer n(DAR/TPA)-and-m(TAB/DHTA)

(1) Preparation of four mixed compound salt monomer

Add 200g of deoxygenated water, 5.12g of 96% NaOH (0.1229mol), 6.65g (0.04mol) of terephthalic acid (TPA) and 1.98g (0.01mol) of 2,5-dihydroxyterephthalic acid (TPA) and 1.98g (0.01mol) in the glass reactor. Formic acid (DHTA), stir and raise the temperature to 50℃ to dissolve into a light brown transparent solution, under the protection of nitrogen, slowly add 8.78g (0.0412mol) 4,6-diaminoresorcinol hydrochloride (DARH, Aqueous solution containing Sn ²⁺ 2646ppm) and 2.93g (0.0103mol) 1,2,4,5-tetraaminobenzene hydrochloride (TABH, Sn ²⁺ 1060ppm) dissolved in 180g deoxygenated water, after adding, stir and heat up to 70℃ Perform hot filtration, wash the wet cake with 180mL deoxygenated water, filter at room temperature and vacuum dry at 70℃ to obtain four monomers of TPA, DAR, DHTA and TAB (mol ratio 0.8:0.8:0.2:0.2, n/m=4) The formed four-mixed composite salt monomer n(DAR/TPA)-and-m(TAB/DHTA) of 20% dihydroxy and phenyltetramine modified PBO was 13.08g (see Figure 1 for IR), and the yield was 83.78%. The average molecular weight of the four-mixed complex salt monomer n(DAR/TPA)-and-m(TAB/DHTA) is M = 312.2802, containing Sn ²⁺ 192ppm. Placed in the environment for 30 days, the appearance is basically unchanged, and the antioxidant stability is good.

(2) Applied in the preparation of quaternary polybenzodiazole liquid crystal polymer (DH)PBI-co-(DH)PBO and monofilament fibers

Add 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0g and n(DAR/TAB)-and-m with n/m=4 in the glass polymerization reactor. (TPA/DHTA) 6.25g (0.020mol, containing Sn ²⁺ 192ppm), formulated into a four-mixed compound salt monomer concentration of 20% (based _{on the total mass of polyphosphoric acid, P 2} O ₅ and the mixed compound salt monomer Calculated) and P ₂ O ₅ initial mass concentration of 86.93% (based _{on the total mass of polyphosphoric acid and P 2} O ₅ ) PPA polymerization reaction system; heated to 100 ℃ under nitrogen protection, 350r/min stirring and dissolving for 1h (Volume expansion), then use 1h to heat up to 160-170℃, fluorescence appears, and then program the temperature at a rate of 5℃/hour for 4h to 190℃ (liquid crystals and filaments appear successively during the process), and stir until the speed drops significantly When the temperature reaches 200r/min or less, the polymerization reaction is finished, and the liquid crystal stock solution of 20% (DH)PBI-co-(DH)PBO of random liquid crystal polymer after polymerization is obtained by stirring and cooling to about 120°C;

Then, manually continuous wire drawing is performed from the prepared liquid crystal stock solution, and the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and dried under vacuum at 110°C for 3 hours to obtain purple-brown (DH) PBI-co-(DH)PBO quaternary liquid crystal polymer monofilament composite fiber (modified link m/(n+m)=20%). The measured intrinsic viscosity is 20.17dL/g (30°C/MSA). The IR of the 20% dihydroxy (DH) and benzimidazole (BI) modified PBO monofilament fiber is shown in Figure 2, the temperature at 5% weight loss by thermogravimetric analysis is 502°C, and the TG-DTG is shown in Figure 3.

Example 2 Preparation and application of four-mixed composite salt monomer n(DAR/TPA)-and-m(TABP/DHTA)

(1) Preparation of four mixed compound salt monomer

Add 200g of deoxygenated water, 5.12g of 96% NaOH (0.1229mol), 6.65g (0.04mol) of terephthalic acid (TPA) and 1.98g (0.01mol) of 2,5-dihydroxyterephthalic acid (TPA) and 1.98g (0.01mol) in the glass reactor. Formic acid (DHTA), stir and raise the temperature to 50℃ to dissolve into a light brown transparent solution, under the protection of nitrogen, slowly add 8.78g (0.0412mol) 4,6-diaminoresorcinol hydrochloride (DARH, An aqueous solution containing Sn ²⁺ 2646ppm) and 3.71g (0.103mol) 3,3',4,4'-tetraaminobiphenyl hydrochloride (TABPH) dissolved in 180g of deoxygenated water, after adding, stir and heat up to 70℃ for heating Filtration, the wet cake was beaten and washed with 180mL deoxygenated water, filtered at room temperature, and vacuum dried at 70°C to obtain four monomers of TPA, DAR, DHTA, TABP (mol ratio 0.8:0.8:0.2:0.2, n/m=4) The four-mixed composite salt monomer n(DAR/TPA)-and-m(TABP/DHTA) of 20% dihydroxy and biphenyltetraamine modified PBO was 14.58g (see Figure 4 for IR), and the yield was 89.04%. The average molecular weight of the four-mixed complex salt monomer n(DAR/TPA)-and-m(TABP/DHTA) is M= 327.4998, containing Sn ²⁺ 181ppm. Placed in the environment for 30 days, the appearance remains unchanged and the oxidation resistance is good.

(2) Applied in the preparation of quaternary polybenzodiazole liquid crystal polymer (DH)PBI-co-(DH)PBO and monofilament fibers

Add 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0g and n(DAR/TPA)-and-m with n/m=4 in the glass polymerization reactor. (TABP/DHTA) 6.55g (0.020mol, containing Sn ²⁺ 181ppm), formulated into a PPA polymerization reaction system with four-mixed double salt monomer concentration of 20.76% and P ₂ O ₅ initial mass concentration of 86.93%, in nitrogen Under protection, the temperature is raised to 100°C and stirred, 350r/min dissolves for 1h (volume expansion), and then the temperature is raised to 170°C for 2h, and the fluorescence appears, and then the temperature is increased at a rate of 10°C/hour for 3h to 200°C (the liquid crystal and the Filament), and stir until the speed drops significantly below 200r/min to complete the polymerization reaction, stir and cool to about 120 ℃ to obtain the random liquid crystal polymer (DH) PBPI-co-(DH) PBO after the polymerization reaction Liquid crystal stock solution

Then, manually continuous wire drawing is performed from the prepared liquid crystal stock solution, and the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and dried under vacuum at 110°C for 3 hours to obtain purple-brown (DH) PBPI-co-(DH)PBO quaternary liquid crystal polymer monofilament fiber (modified link m/(n+m)=20%). The measured intrinsic viscosity is 17.86dL/g (30°C/MSA). The IR of 20% dihydroxy (DH) and bibenzimidazole (BPI) modified PBO monofilament fiber is shown in Figure 5, the temperature at 5% weight loss by thermogravimetric analysis is 560°C, and the TG-DTG is shown in Figure 6.

Example 3 Preparation and application of three-mixed composite salt monomer (DAR)-and-(nTPA/mDHTA)

(1) Preparation of three mixed compound salt monomers

Add 200g of deoxygenated water, 4.27g of 96% NaOH (0.1025mol), 8.22g (0.0495mol) of terephthalic acid (TPA) and 0.10g (0.0005mol) of 2,5-dihydroxyterephthalic acid (TPA) and 0.10g (0.0005mol) of 2,5-dihydroxyterephthalic acid (TPA) in the glass reactor. Formic acid (DHTA), stir and warm up to 50 ℃ to dissolve into a light brown transparent solution, under the protection of nitrogen, slowly add dropwise from 10.97g (0.0515mol) 4,6-diaminoresorcinol hydrochloride (DARH, Sn ²⁺ 2646ppm) dissolved in 180g deoxygenated water solution, after adding, stir and heat up to 70℃ for hot filtration. The wet cake is beaten and washed with 180mL deoxygenated water, filtered at room temperature, and vacuum dried at 70℃. The monomer (mol ratio 0.99:0.01:1.0, n/m=99) is a 1% dihydroxy-modified PBO three-mixed composite salt monomer (DAR)-and-(nTPA/mDHTA) 13.72g (see attached IR) Figure 7), the yield was 89.50%. The average molecular weight of the three-mixed complex salt monomer (DAR)-and-(nTPA/mDHTA) is M = 306.5944, containing Sn ²⁺ 175 ppm. Placed in the environment for 60 days, the appearance remains unchanged, and the antioxidant stability is good.

Change the feed ratio and prepare the three-mixed composite salt monomer (DAR)-and-(nTPA/mDHTA) with m/(n+m)=0, 0.025, 0.05, 0.50 according to the above method with the total mol number of AA monomer being 0.05. The result is:

m/(n+m)=0.000 PBO, 13.61g of the two-mixed composite salt monomer, Sn ²⁺ content of 183ppm, and a small amount of oxidative discoloration within 7 days;

m/(n+m)=0.025 2.5% dihydroxy modified PBO three mixed compound salt monomer 13.83g, Sn ²⁺ content 175ppm, unchanged for 15 days;

m/(n+m)=0.05 5% dihydroxy modified PBO three mixed compound salt monomer 13.92g, Sn ²⁺ content 197ppm, unchanged for 30 days;

m/(n+m)=0.50, 14.70g of the three-mixed composite salt monomer of 50% dihydroxy modified PBO, Sn ²⁺ content 309ppm, unchanged for 60 days;

(2) Used in the preparation of binary polybenzodiazole liquid crystal polymer DHPBO-co-PBO and monofilament fibers

A) 1% dihydroxy modified PBO (1% DHPBO-co-PBO) and monofilament fiber

In the glass polymerization reactor were sequentially added 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0 g and (DAR)-and-(nTPA/mDHTA with n/m=99). ) 6.13g (0.020mol, containing Sn ²⁺ 175ppm) to form a three-mixed double salt monomer concentration of 19.69% and P ₂ O ₅ initial mass concentration of 86.93% PPA polymerization reaction system, heated to 100 under the protection of nitrogen ℃, 350r/min stirring and dissolving for 1h, and then heating up to 155℃ for 1h, and then heating up at a heating rate of 15℃/hour for 2h to 185℃ (liquid crystals and filaments appearing in succession during the process), and stirring to rotate speed When it obviously drops below 200r/min, the polymerization reaction is finished, and the liquid crystal stock solution of the random liquid crystal polymer DHPBO-co-PBO after the polymerization reaction is obtained by stirring and cooling to about 120°C;

Then, manually continuous wire drawing is performed from the prepared liquid crystal stock solution, and the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and dried under vacuum at 110°C for 3 hours to obtain golden yellow DHPBO-co -PBO binary liquid crystal polymer monofilament fiber (modified link m/(n+m)=1%). The measured intrinsic viscosity is 29.31dL/g (30°C/MSA). The IR of the 1% dihydroxy-modified PBO monofilament fiber is shown in Fig. 8, the temperature of the thermogravimetric analysis when the weight loss is 5% is 630°C, and the TG-DTG is shown in Fig. 9.

B) 2.5% dihydroxy modified PBO (2.5% DHPBO-co-PBO) and monofilament fiber

In the glass polymerization reactor, 21.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.2% and 3.7g of P 2} O ₅ and (DAR)-and-(nTPA/mDHTA with n/m=19 were added sequentially. ) 5.10g (0.020mol, containing Sn ²⁺ 175ppm), formulated into a PPA polymerization reaction system with a three-mixed double salt monomer concentration of 20% and a P ₂ O ₅ initial mass concentration of 86.93%. The temperature is increased to Stir and dissolve at 100°C and 350r/min for 1h (volume expansion), then use 1h to heat up to 160°C for golden fluorescence, and then program the temperature at a heating rate of 15°C/hour for 1h to 175°C (liquid crystals and filaments appear in succession during the process) , And stir until the speed drops significantly below 200r/min, the polymerization reaction is over, stir and cool to about 120 ℃ to obtain the random liquid crystal polymer DHPBO-co-PBO liquid crystal stock solution after polymerization; perform manual continuous wire drawing, drawing The monofilament is coagulated in water, washed, and then washed with hot or boiling water to neutrality, and dried in vacuum at 110°C for 3 hours to obtain brown-yellow DHPBO-co-PBO binary liquid crystal polymer monofilament fiber (modified chain Knot m/(n+m)=2.5%). The measured intrinsic viscosity is 28.65dL/g (30°C/MSA), and the temperature is 615°C at 5% weight loss by thermogravimetric analysis. The TG-DTG is shown in Figure 10. .

Comparative Example 1

A) PBO (m=0) and monofilament fiber

In the glass polymerization reactor, 22.0 g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0 g and m=0 (nDAR)-and-(nTPA) 6.13g ( 0.020mol, Sn ²⁺ content 183ppm, and a small amount of oxidative discoloration, has been placed in the environment for 7 days), mixed _{with PPA polymerization with a monomer concentration of 19.69% and a P 2} O ₅ initial mass concentration of 86.93% The reaction system is heated to 100°C under the protection of nitrogen, stirred and dissolved at 350r/min for 1h (volume expansion), then heated to 155°C for 1h, and fluorescence appears, and then program the temperature rise at a heating rate of 15°C/hour for 2h to 185°C ( Liquid crystals and filaments appear successively during the process, and stir until the speed drops significantly below 200r/min to complete the polymerization reaction. Stir and cool to about 120°C to obtain the liquid crystal stock solution of the random liquid crystal polymer PBO after the polymerization reaction; Continuous drawing, the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and then vacuum dried at 110°C for 3 hours to obtain brown-yellow PBO liquid crystal polymer monofilament fiber (modified link m /(n+m)=0%). The measured intrinsic viscosity is 26.78dL/g (30°C/MSA), and the temperature is 612°C at a 5% weight loss by thermogravimetric analysis.

B) 5% dihydroxy modified PBO (5% DHPBO-co-PBO) and monofilament fiber

In the glass polymerization reactor were sequentially added 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0 g and (DAR)-and-(nTPA/mDHTA with n/m=19). ) 6.16g ( ^{0.020mol, containing Sn 2+} 197ppm), formulated into a PPA polymerization reaction system with a three-mixed double salt monomer concentration of 20% and a P ₂ O ₅ initial mass concentration of 86.93%. The temperature is increased to Stir and dissolve at 100°C and 350r/min for 1h (volume expansion), then use 1h to heat up to 155°C for fluorescence, and then program at a heating rate of 15°C/hour for 2h to 185°C (liquid crystals and filaments appear in succession during the process), And stir until the rotation speed drops significantly below 200r/min, the polymerization reaction is finished, cool to about 120 ℃ to obtain the liquid crystal stock solution of random liquid crystal polymer DHPBO-co-PBO after polymerization; carry out continuous wire drawing by hand, and pull out the liquid crystal stock solution of random liquid crystal polymer DHPBO-co-PBO after polymerization. After the monofilament is coagulated in water, washed, and then washed with hot or boiling water to neutrality, it is dried in vacuum at 110°C for 3 hours to obtain brown-yellow DHPBO-co-PBO binary liquid crystal polymer monofilament fiber (modified chain m /(n+m)=5%). The measured intrinsic viscosity is 23.64dL/g (30°C/MSA), and the temperature is 472°C at 5% weight loss by thermogravimetric analysis. The TG-DTG is shown in Figure 10.

C) 50% dihydroxy modified PBO (50% DHPBO-co-PBO) and monofilament fiber

In the glass polymerization reactor were sequentially added 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0 g and (DAR)-and-(nTPA/mDHTA with n/m=1) ) 6.45g ( ^{0.020mol, containing Sn 2+} 309ppm), formulated into a PPA polymerization reaction system with a three-mixed double salt monomer concentration of 20% and a P ₂ O ₅ initial mass concentration of 86.93%. The temperature is raised to Stir and dissolve at 100℃, 350r/min for 1.5h (volume expansion), then use 1h to heat up to 155～160℃ for fluorescence, and then program at a heating rate of 10℃/hour for 3h to 190℃ (liquid crystals and liquid crystals appear successively in the process) Filament), and stir until the speed drops significantly below 200r/min, the polymerization reaction is over, stir and cool to about 120°C to obtain the liquid crystal stock solution of random liquid crystal polymer DHPBO-co-PBO after polymerization; Manual continuous wire drawing is performed in the liquid crystal stock solution, the drawn monofilament is coagulated in water, washed, and then washed with hot or boiling water to neutrality, and dried in vacuum at 110°C for 3 hours to obtain a yellow-brown DHPBO-co-PBO binary liquid crystal Polymer monofilament fiber (modified link m/(n+m)=50%). The measured intrinsic viscosity is 19.77dL/g (30°C/MSA), and the temperature is 468°C at 5% weight loss by thermogravimetric analysis. The TG-DTG is shown in Figure 11.

Example 4 Preparation and application of three-mixed composite salt monomer (DAR)-and-(nHTA/mDHTA)

(1) Preparation of three mixed compound salt monomers

Add 200g of deoxygenated water, 4.27g of 96% NaOH (0.1025mol), 9.06g (0.04975mol) of hydroxyterephthalic acid (HTA) and 0.05g (0.00025mol) of 2,5-dihydroxyp-benzene in the glass reactor. Dicarboxylic acid (DHTA), stir and warm up to 50 ℃ to dissolve into a light brown transparent solution, under the protection of nitrogen, slowly add dropwise from 10.97g (0.0515mol) 4,6-diaminoresorcinol hydrochloride (DARH , Sn ²⁺ 2646ppm) dissolved in 70g deoxygenated water solution, after adding, stir and heat up to 70℃ for hot filtration. The wet cake was beaten and washed with 180mL deoxygenated water, filtered at room temperature, and dried under vacuum at 70℃ to obtain three components: 0.5% dihydroxy modified HPBO triple mixed compound salt monomer (DAR)-and-(nHTPA/mDHTA) formed by monomer (mol ratio 0.995:0.005:1.0, n/m=199) 14.22g (IR see attached picture 12), the yield is 88.25%. The average molecular weight of the three-mixed complex salt monomer (DAR)-and-(nHTA/mDHTA) is M= 322.3538, containing Sn ²⁺ 178ppm. After being placed in the environment for 60 days, the appearance remains unchanged.

(2) Applied in the preparation of binary polybenzodiazole liquid crystal polymer 0.5% DHPBO-co-HPBO and monofilament fiber

In the glass polymerization reactor were sequentially added 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15% and P 2} O ₅ 3.0 g and (DAR)-and-(nTPA/mHTA with n/m=1. ) 6.45g ( ^{0.020mol, containing Sn 2+} 178ppm), formulated into a PPA polymerization reaction system with a three-mixed double salt monomer concentration of 20.10% and an _{initial mass concentration of P 2} O ₅ of 86.93%; under the protection of nitrogen, the temperature is raised to Stir and dissolve at 100℃, 350r/min for 1h (volume expansion), and then use 1h to heat up to 145～150℃ for fluorescence appearance, and then program the temperature for 3h to 180℃ at a heating rate of 10℃/h (liquid crystal and silk appear successively in the process) When the rotation speed drops significantly below 200r/min, the polymerization reaction is finished, and the polymerization reaction is finished by stirring and cooling to about 120°C to obtain the liquid crystal stock solution of the random liquid crystal polymer DHPBO-co-HPBO after the polymerization reaction;

Then, manually continuous wire drawing is performed from the prepared liquid crystal stock solution, and the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and dried under vacuum at 110°C for 3 hours to obtain purple-brown DHPBO-co -HPBO binary liquid crystal polymer monofilament fiber (modified link m/(n+m)=0.5%). The measured intrinsic viscosity is 27.86dL/g (30°C/MSA). The IR of 0.5% dihydroxy-modified HPBO monofilament fiber is shown in Fig. 13, the temperature at 5% weight loss by thermogravimetric analysis is 606°C, and the TG-DTG is shown in Fig. 14.

Comparative Example 2 Binary polybenzodiazole liquid crystal polymer 0.5% DHPBO-co-HPBO and monofilament fiber (preparation method by copolycondensation of two mixed compound salt monomers)

In the glass polymerization reactor were sequentially added 22.0g of polyphosphoric acid (PPA) with a mass concentration of _{P 2} O _{5 of 85.15%, P 2} O ₅ 3.0g and composite salt monomer: HD 6.413g (0.0199mol, containing Sn ²⁺ 1560ppm) and DHD 0.034g ( ^{0.0001mol, containing Sn 2+} 212ppm), formulated into a PPA polymerization reaction system with a total concentration of n=m composite salt monomers of 20.50% and an _{initial mass concentration of P 2} O _{5 of 86.93%.} Under the protection of nitrogen, heat up to 100℃, stir and dissolve at 350r/min for 1h (volume expansion), then use 2h to heat up to 150℃, fluorescence appears, and then program the temperature for 4h to 190℃ at a heating rate of 10℃/hour (appears in succession during the process) Liquid crystals and filaments), and stir until the rotation speed drops significantly below 200r/min to complete the polymerization reaction, stir and cool to about 120°C to obtain the liquid crystal stock solution of the random liquid crystal polymer DHPBO-co-HPBO after polymerization;

Then, manually continuous wire drawing is performed from the prepared liquid crystal stock solution, and the drawn monofilament is coagulated in water, washed, and then washed with hot water or boiling water to neutrality, and dried under vacuum at 110°C for 3 hours to obtain purple-brown DHPBO-co -HPBO binary liquid crystal polymer monofilament fiber (modified link m/(n+m)=0.5%). The measured intrinsic viscosity is 25.12dL/g (30°C/MSA). The IR of 0.5% dihydroxy-modified HPBO monofilament fiber is shown in Fig. 13. The temperature at 5% weight loss by thermogravimetric analysis is 590°C, and the TG-DTG is shown in Fig. 15.

Application Example 1 The application of liquid crystal polymer 1% DHPBO-co-PBO in the preparation of PBO high-performance fiber

1) High-performance 1% DH-PBO-AS fiber (see Figure 16 for the process flow, see Figure 18 for the device and flow chart of the multi-stage gradient coagulation bath, and see Example 3 (2) for the reaction formula)

_{Add 13.82kg 85.0% PPA and 3.46kg P 2} O ₅ into the 25L double planetary agitated pre-polymerization pressure vessel (101), close the pre-polymerization vessel, and add 3.66kg 1% dihydroxy-modified PBO n after stirring for 3 minutes. /m=99 triple mixed double salt monomer (DAR)-and-(nTPA/mDHTA) (0.0119mol, containing Sn ²⁺ 198ppm), formulated into a PPA polymerization reaction system with a monomer concentration of 17.45%, protected by nitrogen and stirred In the next 40 minutes, the prepolymerization is completed by slowly raising the temperature from 90°C to 160°C (prepolymer η11.82dL/g is measured). It takes 10 minutes to quickly transfer the cylinder and materials of the prepolymerization kettle to the pressing device, using an automatic hydraulic feeding device The prepolymerized materials were sequentially pressed into the 25/48 twin screw machine (102-1, divided into four sections to control the temperature 160, 175, 190, 170 ℃), and the 58/48 twin screw machine (102-2, four section control) Temperature 170℃, 175℃, 180℃, 180℃), control the appropriate screw speed, carry out the reaction and extrusion polymerization of the material with a total residence time of 1h in two tandem screw machines, and then pass the high temperature of the degasser (103) After vacuum degassing and high-viscosity filter (104) at 170℃, it will be used as 1% dihydroxy-modified PBO liquid crystal spinning dope (1% DHPBO-co-PBO 14.22%, η32.87dL/g) into spinning Work section

With the help of the melt booster pump at the outlet of the deaerator, the liquid crystal spinning source is hydraulically fed into the spinning assembly preheated to 170℃ in the spinning machine (201), and the feed is precisely controlled by the spinning metering pump. ～20MPa 170℃ through the spinneret (PRB90-241-0.22X0.6) high-pressure jetting of dry filaments, and the dry filament bundles are quickly stretched in a hot air bath (202) at 50-60℃ (drawing ratio>25), Pulled by the tractor (204) into the first to fourth stage double gradient coagulation bath (203-1,2,3,4) (the phosphoric acid concentration respectively: 22-28, 8-12, 3-5, 1-1.5) %; the temperature is respectively: 48-56, 38-46, 28-36, 18-26℃) Carry out stepwise coagulation and stretching to make the fiber compact, and then pass the water washing with tension isolation in 204, and under the traction of the washing machine Enter the alkaline washing tank (205) for neutralization and washing, and finally through the double drum washing machine (206) water cycle washing, steam dryer (207) 120-140 ℃ after drying, the winder (208) at 80-90m/ Min line speed rewinding, 1% dihydroxy modified PBO precursor (-AS) fiber (golden yellow, 241f multifilament) is obtained. The measured water content is 6.23%, η32.11dL/g;

Deep drying of AS fiber: the AS fiber (6.23% water content) produced by dry jet wet spinning steam drying, air drying at 300°C for 12 seconds in the drying tunnel of the heat treatment device (301) in Figure 19, and winding to obtain the depth The dried and dehydrated 1% HPBO-co-PBO-AS fiber (water content 0.8%) has a dehydration rate of 5.43%, and its appearance is basically unchanged. The linear density of the 241f multifilament measured is 702dtex (in which the single filament fineness is 2.91dtex ). The tensile strength is 3.63GPa and the modulus is 152.3GPa. Its IR is the same as in Figure 8. The temperature at 5% weight loss is 617°C, Figure 17.

2) High performance 1% DH-PBO-HM fiber

Heat setting treatment: The HPBO-co-PBO-AS composite fiber (6.23% water content) produced in 1) is directly placed in the fiber heat treatment device (301) in Fig. 3, and passed through a wire feeder under a given tension (about 10%). Fiber tensile strength), heat treatment for 12 seconds in a 6-meter-long drying tunnel at 500°C in a nitrogen atmosphere, and obtain 1% DH-PBO high modulus (-HM) fiber from a winding machine at a speed of 30 m/min. The tensile strength of the fiber is 3.55 GPa and the modulus is 205 GPa. The appearance of the fiber is bronze.

Application Example 2 Application of recycled PPA in the preparation of liquid crystal polymer 1% DHPBO-co-PBO and its high-performance fiber

Replace 85.0% PPA with recycled 85.0% PPA (total Sn content 51.6ppm). Others are also tested according to the feeding and operation of Application Example 2, and the obtained 1% dihydroxy-modified PBO precursor η35.47dL/g; Tensile strength is 3.58GPa. Its IR is the same as in Figure 15. The temperature at 5% weight loss is 621°C.

Therefore, recycling 85.0% PPA (refer to the method of JP 1996-302017A patent) can be fully recycled and applied to the preparation of high-performance fibers. If the Sn ²⁺ content in the multi-mixed salt substitute is controlled within 200 ppm, it is estimated that it can be recycled at least 15 times. It can not only achieve clean production but also produce a circular economy.

If Sn ^{2+ is} used as an antioxidant, use the ^{polycondensation process of DAR2HCl (containing Sn 2+} 3000ppm) and TPA to replace the three-mixed double salt monomer (DAR)-and-(nTPA/mDHTA) (containing Sn ²⁺ 198ppm) For self-condensation, the recycled PPA can only be recycled once or cannot be recycled.

According to the material balance calculation, the present invention uses a multi-mixed composite salt to replace the mixing and polycondensation of DAR2HCl and TPA, and the recycling economic benefit generated by the recycling of the polymerization medium reaches 41,900 yuan/ton fiber. Moreover, the 25% waste phosphoric acid aqueous solution with a yield of 23.2484 tons/ton of 1% DH-PBO-HM fiber is not recycled and reused, and wastewater treatment is required.

Enumerated above are only a few specific examples of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All modifications that can be directly derived or associated by a person of ordinary skill in the art from the disclosure of the present invention should be considered as the protection scope of the present invention.

Claims (29)

1. A type of multi-mixed compound salt monomer, characterized in that: the structure of the multi-mixed compound salt monomer is as shown in formula I, formula II or formula III, and the multi-mixed compound salt monomer contains an equal number of carboxyl groups and Amino groups, and all carboxyl groups and an equal number of amino groups are ionically bonded with carboxyamine salts to form a multi-mixed composite salt; among them, the structure shown in formula I is a four-mixed double-salt monomer, and its molecule is composed of two AA monomers and two pairs of AA monomers. The BB monomer is formed by the carboxyamine salt ionic bond; the structure shown in formula II or formula III is a three-mixed composite salt monomer, which is composed of two AA monomers and one BB monomer through the carboxyamine salt ionic bond:

   

   In the formula: n and m are natural numbers, which respectively represent the number of molecules of each AA monomer and BB monomer in the composition of the mixed compound salt monomer;

   m and n meet the following conditions: m/(m+n) = 0.005-0.50;

   X represents O atom or S atom;

   Ar ₁ and Ar ₂ are each independently selected from the following tetravalent organic groups connected with two hydroxyl groups or mercapto groups and two amino groups or four amino groups on the aromatic ring:

   

   Ar is selected from one of the following divalent organic groups connected to two carboxylates in the para position of the aromatic ring:

   

   Ar _{0 is} selected from the following divalent organic groups with two carboxylates connected to the para position of the aromatic ring:

   
2. The multi-mixed composite salt monomer according to claim 1, wherein when the multi-mixed composite salt monomer is a four-mixed composite salt monomer represented by formula I, m and n satisfy the following conditions: m /(m+n) = 0.005-0.20, preferably 0.01-0.20.
3. The multi-mixed complex salt monomer according to claim 1, wherein when the multi-mixed complex salt monomer is a three-mixed complex salt monomer represented by formula II or formula III, m and n satisfy the following Conditions: m/(m+n) = 0.005-0.025, preferably 0.005-0.01.
4. The multi-mixed composite salt monomer according to any one of claims 1-3, characterized in that:

   

   Choose from one of the following structures:

   

   

   Choose from one of the following structures:

   

   ^- OOC-Ar-COO ^- is selected from one of the following structures:

   
5. The multi-mixed complex salt monomer according to any one of claims 1 to 3, wherein the four-mixed complex salt monomer compound represented by formula I is selected from one of the following:

   

   
6. The multi-mixed complex salt monomer according to any one of claims 1 to 3, wherein the three-mixed complex salt monomer represented by formula II is selected from one of the following:

   
7. The multi-mixed complex salt monomer of claim 6, wherein the three-mixed complex salt monomer represented by formula II is one of the following: (DAR)-and-(nTPA/mDHTA), (DAR)- and-(nHTA/mDHTA), where m/(m+n) = 0.005-0.01.
8. The multi-mixed complex salt monomer according to claim 1, wherein the three-mixed complex salt monomer represented by formula II is (DAR)-and-(nHTA/mDHTA with m/(m+n)=0.005 ), m/(m+n)=0.01 (DAR)-and-(nTPA/mDHTA).
9. The multi-mixed complex salt monomer according to any one of claims 1 to 3, wherein the three-mixed complex salt monomer represented by formula III is selected from one of the following:

   
10. The multi-mixed composite salt monomer according to any one of claims 1-9, wherein the Sn ²⁺ content in the multi-mixed composite salt monomer is less than 200 ppm.
11. The multi-mixed composite salt monomer according to any one of claims 1-10, characterized in that: the multi-mixed composite salt monomer is in the storage process, wherein

    

    At least partly due to oxidation

    
12. A method for preparing a multi-mixed composite salt monomer according to any one of claims 1 to 3, characterized in that: the preparation method is composed of AA monomer and BB monomer hydrochloride in an alkaline oxygen-free aqueous solution. It is prepared by neutralization compound reaction; the AA monomer is _{a dibasic acid in the para position of the aromatic ring Ar or Ar 0} , which is selected from the AA monomers represented by formula IX and formula IX'respectively; the BB monomer The hydrochloride is selected from the BB monomer hydrochloride represented by the formula X and the formula X', and the combination of the AA monomer and the BB monomer hydrochloride is one of the following:

    1) One type of IX+one type of IX’+one type of X+one type of X’;

    2) One type of IX+one type of IX’+one type of X;

    3) One type of IX+one type of IX’+one type of X’;

    The feeding ratio of the AA monomer and the BB monomer hydrochloride satisfies the following conditions: the molar ratio of the AA monomer represented by the formula IX' to the AA monomer represented by the formula IX is m:n and/or the formula X' The molar ratio of the BB monomer hydrochloride shown by the formula X to the BB monomer hydrochloride shown by the formula X is m:n;

    

    

    In the formula: X, Ar, Ar ₀ , Ar ₁ , Ar _{2 are} as defined in the cited claims, and x and y are the number of HCl molecules in the BB monomer hydrochloride, respectively.
13. The preparation method according to claim 12, characterized in that: the preparation method is prepared according to the following steps:

    1) Dissolve AA monomer in a deoxygenated aqueous solution of a certain equivalent of alkaline substance to obtain a deoxygenated aqueous solution of AA monomer diformate;

    2) Under nitrogen protection and stirring, dissolve a certain amount of BB monomer hydrochloride in deoxygenated water to form an aqueous solution, and slowly add it to the deoxygenated aqueous solution of AA monomer diformate at 60-70°C for neutralization and compounding reaction. Formation of multiple mixed compound salt monomer precipitation;

    3) Stir and cool to room temperature under nitrogen protection, filter, wash with oxygen-free water, and vacuum dry to obtain the multi-mixed composite salt monomer.
14. The preparation method according to claim 13, wherein the alkaline substance in step 1) is one or more of NaOH, KOH, NaHCO ₃ , KHCO ₃ , Na ₂ CO ₃ , and K ₂ CO ₃ The said certain equivalent means that the equivalent of the basic substance is 0.99-1.00 times the total equivalent of HCl in the BB monomer hydrochloride; in step 2), the said certain amount refers to the BB monomer hydrochloric acid The molar ratio of salt to AA monomer is 0.99-1.04; preferably 1.01-1.03.
15. The preparation method according to any one of claims 12-14, characterized in that the Sn content in the multi-mixed composite salt monomer is controlled to be less than 200 ppm by controlling the amount of solvent water.
16. The application of the multi-mixed composite salt monomer according to any one of claims 1 to 3 in the preparation of multi-component polybenzodiazole liquid crystal polymer by self-condensation, the application is: Formula I, Formula II or Formula III The shown multi-mixed composite salt monomers _{are self-condensed in a P 2} O ₅ -PPA system to prepare the corresponding multi-element polybenzodiazole liquid crystal polymer of formula V, formula VI or formula VII;

    

    In the formula, n, m, X, Ar ₁ , Ar ₂ , Ar, and Ar _{0 have} the same definitions as the cited claims, and k is a random variable, 1≤k≤m-1.
17. The application according to claim 16, characterized in that: the application specifically includes the following steps:

    _{1) Add quantitative P 2} O ₅ to polyphosphoric acid (PPA) in the glass polymerization reaction column to _{make the P 2} O ₅ reaction basically dissolve (persons skilled in the art can use stirring, heating, etc. to promote the dissolution according to actual needs. ), slowly add the selected multi-mixed compound salt monomer to form a PPA polymerization reaction system; in the PPA polymerization reaction system, the mass amount of the multi-mixed compound salt monomer accounts for polyphosphoric acid, P ₂ O ₅ and multi-mixed 15-25% of the total mass consumption of the composite salt monomer, and the mass consumption of P ₂ O ₅ accounts for 86.5-88.0% of the total mass consumption of polyphosphoric acid and P ₂ O _5;

    2) _{Under the protection of N 2} , the PPA polymerization reaction system is stirred and dissolved at 100-130°C for 50-90 minutes, and then slowly heated to 145-170°C for 0.5-2h at a stirring rate of 300-400r/min. At this time, the whole body appears. Fluorescence, and then program the temperature to 170-200°C at a rate of 5-15°C/hour (liquid crystals and filaments appear successively during the process), and stir until the speed drops below 200r/min to complete the polymerization reaction. Stir and cool to 120～150℃, the PPA liquid crystal stock solution of the corresponding multi-element polybenzodiazole liquid crystal polymer can be obtained.
18. The application according to claim 17, characterized in that: the application further comprises step 3): controlling the temperature of the liquid crystal stock solution of the multi-element polybenzodiazole liquid crystal polymer obtained in step 2) at 120-150°C The monofilament fiber of multi-alloy polybenzodiazole liquid crystal polymer is prepared by manual continuous drawing, coagulation, water washing, and vacuum drying.
19. A type of multi-element polybenzodiazole liquid crystal polymer, characterized in that: the structure of the multi-element polybenzodiazole liquid crystal polymer is as shown in formula V, formula VI or formula VII, and is defined by one of claims 1-3. The multi-mixed composite salt monomers represented by the formula I, the formula II or the formula III are obtained by self-condensation, and the intrinsic viscosity of the multi-component polybenzodiazole liquid crystal polymer is 8-40 dL/g;

    

    In the formula, n, m, X, Ar ₁ , Ar ₂ , Ar, and Ar _{0 have} the same definitions as the cited claims, and k is a random variable, 1≤k≤m-1.
20. The multi-component polybenzodiazole liquid crystal polymer of claim 19, wherein the structure of the multi-component polybenzodiazole liquid crystal polymer of formula V is selected from one of the following:

    

    
21. The multi-component polybenzodiazole liquid crystal polymer of claim 19, wherein the structure of the multi-component polybenzodiazole liquid crystal polymer represented by formula VI is selected from one of the following:

    
22. The multi-element polybenzodiazole liquid crystal polymer of claim 19, wherein the structure of the multielement liquid crystal polymer represented by formula VII is selected from one of the following:

    
23. The application of the multi-mixed composite salt monomer according to any one of claims 1 to 3 in the preparation of multi-alloy polybenzodiazole liquid crystal polymer fibers, characterized in that: the application includes:

    1) Using polyphosphoric acid as the medium and phosphorus pentoxide as the dehydrating agent, the self-condensation of the multi-mixed composite salt monomers represented by formula I, formula II or formula III is carried out under the protection of nitrogen to obtain formula V and VI Or the liquid crystal spinning dope of the multi-element polybenzodiazole liquid crystal polymer shown in VII;

    2) The liquid crystal spinning dope of the multi-element polybenzodiazole liquid crystal polymer adopts the liquid crystal spinning technology of dry-jet wet method to prepare multi-element liquid crystal polymer fiber, the fiber is a nascent multifilament composite fiber or a high modulus multifilament composite fiber.
24. The application according to claim 23, wherein the application specifically includes the following steps:

    1) Pre-polymerization: Add a certain concentration of PPA and a quantitative amount of P ₂ O ₅ in the pre-polymerization pressure vessel to form a PPA containing 86.5-88% P ₂ O _5. Seal the polymerization vessel and stir it evenly. Under protection, add the selected multi-mixed compound salt monomers in sequence within 5-15min, and control the feeding temperature below 90℃ to form a polymerization reaction system with the multi-mixed compound salt monomer mass concentration of 15-25%, and replace it with nitrogen repeatedly. After air, under the protection of nitrogen, slowly increase the temperature from 90°C to 160°C within 0.5～2h to complete the prepolymerization, stop stirring, and remove the cylinder of the prepolymerization pressure vessel;

    Reactive extrusion polymerization in the screw machine: quickly transfer the barrel containing the prepolymer liquid crystal liquid to the pressing device, and use the feeding device to sequentially press the prepolymerized material into the series twin screw machine-1 and twin screw machine- 2. The twin-screw machine-1 is a four-stage temperature control zone at 160℃～190℃, and the twin-screw machine 2 is a four-stage temperature control zone at 170～180℃. The total residence time of the reaction extrusion polymerization of the machine material is 50-70min, and then it is strictly degassed at 160-170℃ by a deaerator and filtered by a high-viscosity filter, as the liquid crystal of the corresponding multi-element polybenzodiazole liquid crystal polymer Spinning dope enters the spinning section;

    2) The liquid crystal spinning element is hydraulically inserted into the spinneret which has been preheated to 160～180℃ in the spinning machine, and the feed amount is precisely controlled by the spinning metering pump. The temperature is 5～20MPa and 160-180℃. The spinneret jets out the dry tow at high pressure, and the dry tow is rapidly stretched in a hot air bath at 40-60°C, and then enters the coagulation bath where the coagulation liquid is an aqueous phosphoric acid solution for coagulation and stretching, so that the fiber is compacted, and then tensioned by the belt The traction and preliminary water washing of the isolated and water-washed tractor, and enter the alkaline washing tank under the traction of the double-roller washing machine to remove residual phosphoric acid, and finally through the double-roller washing machine for water cycle washing, the 120th of the double-roller steam dryer After drying at ~150°C, it is wound up by a winder at a certain linear speed to obtain a multi-component polybenzodiazole liquid crystal polymer as a spun multifilament composite fiber.
25. The application according to claim 24, characterized in that: the application further comprises the following steps: the prepared multi-element liquid crystal polymer nascent multifilament fiber is directly placed in the fiber heat treatment device through a wire-feeding machine, under a given tension Heat treatment in a drying tunnel at 520-600°C for 10-30 seconds in a nitrogen atmosphere, and obtain a multi-element polybenzodiazole liquid crystal polymer high modulus multifilament fiber from a winding machine at a winding speed of 30-50m/min.
26. The application according to claim 24 or 25, wherein the coagulation liquid adopts a multi-stage double-gradient coagulation bath, specifically an operation of n-stage coagulation baths in series and reverse operation of fibers and coagulation liquid:

    The multi-stage gradient coagulation bath is composed of n coagulation baths in series, the value of n is 3-5, and the setting height from coagulation bath 1 to coagulation bath n is gradually raised, and each coagulation bath is set There is an overflow port so that the coagulation liquid in the coagulation bath n can overflow into the adjacent coagulation bath n-1, and the coagulation liquid in the coagulation bath n-1 can overflow into the coagulation bath n-2, and so on; The coagulation liquid in each coagulation bath is an aqueous phosphoric acid solution. The concentration of the phosphoric acid aqueous solution in the coagulation bath is represented by C, and the _{concentration decreases from C 1} to C _n ; the temperature of the coagulation bath for setting the coagulation bath is represented by T, from T ₁ to T _n The temperature of the coagulation liquid decreases successively; during the coagulation process, the high-pressure sprayed and stretched dry tow is successively passed through the coagulation bath 1, the coagulation bath 2 until the coagulation bath n, and at the same time, the coagulation bath n is continuously supplied with water to make the coagulation bath The coagulation liquid in n overflows into the coagulation bath n-1 to dilute the coagulation liquid in the coagulation bath n-1, and solves the problem of the increase in the concentration of the coagulation liquid caused by the spread of the solvent in the coagulation bath n-1 to maintain continuity During operation, the concentration of phosphoric acid in coagulation bath n-1 is constant; in the same way, other adjacent coagulation baths also maintain a constant concentration of phosphoric acid in the coagulation bath through the same process, and finally discharge a higher concentration of phosphoric acid aqueous solution at the overflow of coagulation bath 1.
27. The application according to claim 24 or 25, characterized in that: in step 1), the four-stage temperature control zone of 160°C～190°C in the twin screw machine-1 is set to 160°C, 175°C, and 190°C successively. ℃, 170℃; The four-stage temperature control zone of 170～180℃ in the twin-screw machine-2 is set to 170℃, 175℃, 180℃, and 180℃ successively.
28. The application according to claim 26, characterized in that: in step 2), the coagulation liquid adopts a multi-stage double-gradient coagulation bath, and specifically adopts the operation of four-stage coagulation bath in series and reverse operation of fibers and coagulation liquid. The phosphoric acid concentration and temperature were set as C ₁ ＝22-28wt%, C ₂ ＝8-12wt%, C ₃ =3-5wt%, C ₄ =11.5wt% and T ₁ ＝48-56℃, T ₂ = 38-46°C, T ₃ = 28-36°C, T ₄ = 18-26°C.
29. The multi-element polybenzodiazole liquid crystal polymer fiber obtained by the application of claim 23, wherein the intrinsic viscosity of the multi-element polybenzodiazole liquid crystal polymer is 8-40 dL/g; The properties of the nascent multifilament fiber are: the diameter of a single fiber is 12-16um, the fineness is 2.6-3.0dtex, the moisture content is 5-7%, the tensile strength is 3.4-3.7GPa, and the modulus is 130-160GPa; the high modulus multifilament The fiber properties are: the diameter of a single fiber is 12-16um, the fineness is 2.6-3.0dtex, the tensile strength is 3.5-3.6GPa, and the modulus is 200-210GPa.

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