阅读说明：本技术 一种聚对苯撑苯并二噁唑纤维的制备方法 (Preparation method of poly (p-phenylene-benzobisoxazole) fibers ) 是由 潘志军 金宁人 顾峰雷 戴学明 于 2019-09-16 设计创作，主要内容包括：本发明涉及一种聚对苯撑苯并二噁唑纤维的制备方法,包括下述步骤：4,6-二氨基间苯二酚磷酸盐与对苯二甲酸在多聚磷酸和五氧化二磷的混合介质中,在惰性气体保护下,在100～200℃下聚合反应得到聚对苯撑苯并二噁唑。本发明采用4,6-二氨基间苯二酚磷酸盐(DARP)与对苯二甲酸(TPA)聚合,不但节省了脱氯化氢气体的时间,而且大大降低了对设备的要求(不需要在高温下脱除氯化氢)。(The invention relates to a preparation method of poly-p-phenylene benzobisoxazole fiber, which comprises the following steps: polymerizing 4, 6-diaminoresorcinol phosphate and terephthalic acid in a mixed medium of polyphosphoric acid and phosphorus pentoxide under the protection of inert gas at 100-200 ℃ to obtain the poly (p-phenylene-benzobisoxazole). The invention adopts 4, 6-diamino resorcinol phosphate (DARP) and terephthalic acid (TPA) for polymerization, thereby not only saving the time of dehydrochlorination gas, but also greatly reducing the requirement on equipment (hydrogen chloride does not need to be removed at high temperature).)

1. The preparation method of the poly-p-phenylene benzobisoxazole is characterized by comprising the following steps: polymerizing 4, 6-diaminoresorcinol phosphate and terephthalic acid in a mixed medium of polyphosphoric acid and phosphorus pentoxide under the protection of inert gas at 100-200 ℃ to obtain the poly (p-phenylene-benzobisoxazole).

2. The method for preparing poly-p-phenylene benzobisoxazole as claimed in claim 1 further comprising drawing the filaments, washing the filaments with water, then with weak base water, then with clear water, and finally drying the filaments to obtain poly-p-phenylene benzobisoxazole fibers.

3. the method for producing polyparaphenylene benzobisoxazole according to claim 1 or 2, wherein before the polymerization reaction, assuming that the mass of polyphosphoric acid is a, the percentage of P ₂ O ₅ in polyphosphoric acid is b, the mass of additional phosphorus pentoxide is c, and the mass of 4, 6-diaminoresorcinol phosphate is d, X1 ═ (ab + c + d 0.583 ═ 0.72)/(a + c + d 0.583) is 87 to 89%, and when the polymerization reaction is completed, X2 ═ (ab + c + d 0.583 ═ 0.72)/(a + c + d 0.583+ wt (H ₂ O)) is 82 to 84%, and wt (H ₂ O) is the mass of water produced by the polymerization reaction.

4. the method for preparing polyparaphenylene benzobisoxazole according to claim 1 or 2, characterized in that: the dosage of the polyphosphoric acid is 2-4 times of the mass of the 4, 6-diaminoresorcinol phosphate; the molar ratio of the terephthalic acid to the 4, 6-diaminoresorcinol phosphate is 0.95-1.02: 1.

5. The method for preparing polyparaphenylene benzobisoxazole according to claim 1 or 2, which is characterized by comprising: adding polyphosphoric acid and phosphorus pentoxide into a reaction bottle under the protection of nitrogen, stirring, heating to obtain a mixed medium, adding 4, 6-diaminoresorcinol phosphate and terephthalic acid, then preserving heat at 100-120 ℃ for 1-4 h, preserving heat at 120-150 ℃ for 1-4 h, preserving heat at 150-170 ℃ for 0.2-2 h, and finally preserving heat at 170-185 ℃ for 2-6 h to obtain the poly (p-phenylene-benzobisoxazole).

6. The method for preparing polyparaphenylene benzobisoxazole as claimed in claim 5, wherein: the temperature of polyphosphoric acid and phosphorus pentoxide is 100-120 ℃, and stirring is carried out for 0.2-2 h.

7. The method for preparing polyparaphenylene benzobisoxazole according to claim 1 or 2, characterized in that: the terephthalic acid is pretreated before reaction, and the pretreatment method comprises the following steps: and (3) grinding for 3-4 h by using a stainless steel ball mill under the condition of 600 r/min.

8. The method for preparing polyparaphenylene benzobisoxazole according to claim 1, characterized in that: the 4, 6-diaminoresorcinol phosphate is prepared by the following method: adding 4, 6-dinitroresorcinol, a solvent and a catalyst into an autoclave, reacting at the temperature of 40-60 ℃ and under the pressure of 0.2-1.0 MPa, filtering and recovering the catalyst under the protection of nitrogen after the reaction is finished, dropwise adding the filtrate into a phosphoric acid aqueous solution, fully stirring, and performing post-treatment to obtain the 4, 6-diaminoresorcinol phosphate.

9. The method for preparing polyparaphenylene benzobisoxazole according to claim 8, characterized in that: the solvent is any one of methanol, ethanol, methanol/DMF (dimethyl formamide), dioxane and a sodium hydroxide aqueous solution, and the using amount of the solvent is 6-12 times of the mass of 4, 6-dinitroresorcinol.

10. The method for preparing polyparaphenylene benzobisoxazole according to claim 8, characterized in that: the catalyst is Raney nickel or 1-10% palladium carbon or 1-10% platinum carbon, and the amount of the catalyst is 1-10% of the mass of 4, 6-dinitroresorcinol.

Technical Field

The invention belongs to the technical field of material science, and particularly relates to a preparation method of poly (p-phenylene-benzobisoxazole) fibers.

background

The poly-p-phenylene benzobisoxazole fiber (PBO) is invented by American air force aerodynamic development researchers, firstly, the American Stanford university institute (SRI) owns the basic patent of polybenzazole, then the American Dow chemical company is authorized, and the PBO is developed industrially, meanwhile, the original monomer synthesis method is improved, the new process hardly generates isomer by-products, the yield of the synthesized monomer is improved, and the industrialization foundation is laid.

The PBO fiber has the advantages of good heat resistance, high strength and modulus and the like, and is known as super fiber in the 21 st century. The product (trade name Zylon) is produced exclusively by Toyobo company of Japan according to formula (1) in mixed polycondensation and spinning monopoly from 1998, and the annual output of Toyobo company can reach 400 tons at present, and technical blockade and product prohibition are implemented in China. Mainly used as a military requirement for European, American and Japanese sales, and the price is up to 3000 yuan/kg.

Due to the difficulty in the source of the monomer 4, 6-diaminoresorcinol hydrochloride (DARH), the HCl removal time in the process of the formula (1) is more than 30h, the semi-continuous polymerization operation is complex, and the industrialization process is extremely difficult. Although Toyobo company also adopts the patent technology formula (2) of preparing composite salt TDH first and then self-polycondensation to prepare PBO fiber, HCl is not required to be removed, and higher molecular weight is obtained compared with polymerization, but the oxidation of composite salt TDH is faster than DARH, so that the industrialization operation is more difficult, and the self-polycondensation route in the industrialization transformation is automatically abandoned by Toyobo.

Although many companies are currently researching the preparation method of PBO, few companies have been available for industrial production, mainly because the main monomer used for PBO is 4, 6-Diaminoresorcinol (DAR) hydrochloride, which needs to be first purified at high temperature in the early stage of polymerization, and there are two problems in the process of dehydrochlorination: (1)4, 6-Diaminoresorcinol (DAR) is extremely unstable, and is rapidly discolored and oxidized when meeting oxygen, so that the polymerization reaction is not favorably carried out; (2) the generated hydrogen chloride gas is very corrosive to equipment at high temperature, which is one of the main reasons for limiting industrial production.

The Zhuang-inspired Xin et al published the article "preparation of 4, 6-diaminoresorcinol phosphate and its stabilization by PPA" in the university of eastern China, and the phosphate was prepared by the polyphosphoric acid (PPA) method and its structure was characterized. The poly (phenylenebenzobisoxazole) (PBO) having a high degree of polymerization can be obtained by subjecting the stabilized monomer and terephthalic acid to a polycondensation reaction in a medium of PPA. The research only prepares the polymer in PPA medium, the intrinsic viscosity number only reaches 17, and the polymerization degree (viscosity) of the obtained fiber does not meet the industrial requirement.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a novel preparation method of high-strength poly (p-Phenylene Benzobisoxazole) (PBO), which can solve the corrosion condition of equipment, has the advantages of environmental protection, economy and the like, and is suitable for industrial production.

In order to achieve the purpose, the invention adopts the technical scheme that:

A preparation method of poly-p-phenylene benzobisoxazole comprises the following steps: polymerizing 4, 6-diaminoresorcinol phosphate and terephthalic acid in a mixed medium of polyphosphoric acid and phosphorus pentoxide under the protection of inert gas at 100-200 ℃ to obtain the poly (p-phenylene-benzobisoxazole).

the invention can greatly shorten the polymerization time (mainly saving the time of dehydrochlorination gas), avoid the condition that equipment is corroded, and is more beneficial to industrial production. The reaction formula is as follows:

preferably, the method further comprises the step of drawing, wherein the obtained filaments are washed by water, then washed by weak alkaline water, washed by clean water and finally dried by blowing to obtain the poly-p-phenylene benzobisoxazole fibers.

The polyphosphoric acid (PPA) is a solvent and a cyclizing agent, if only PPA is used as a reaction medium, the content of phosphorus pentoxide in the polyphosphoric acid is only 84-86%, the polymerization degree of fibers obtained by the reaction is limited, if a proper amount of phosphorus pentoxide (P ₂ O ₅) is additionally added, the phosphorus pentoxide reacts with water generated by polymerization to generate phosphoric acid, the reaction is favorably carried out rightward, the polymerization degree and viscosity of polymer fibers are improved, the more the phosphorus pentoxide (P ₂ O ₅) is added, the stronger the polymerization capacity is, the higher the molecular weight of the obtained polymer is, but the more P ₂ O ₅ is, the higher the system viscosity is, stirring is difficult, the content of P ₂ O ₅ in the mixed medium needs to be controlled to be the optimal proportion, namely the added amount of the phosphorus pentoxide is controlled, the mass of the polyphosphoric acid is preferably a before the polymerization reaction, the content of P ₂ O ₅ in the polyphosphoric acid is b by mass percent, the added amount of the resorcinol is c, the mass of the resorcinol, the 6-diaminophosphate is 4, the d is preferably, the added amount of the phosphate is 4, the c + 583 a + 5H 3, the c + 5H 3 is 0.72, and the polymerization reaction is completed when the reaction is completed (X633 + 5H).

X1 represents the percentage of the total phosphorus pentoxide content in the solvent at the initial stage of the reaction, a b represents the phosphorus pentoxide content in the polyphosphoric acid, 0.583 represents the phosphoric acid content in the 4, 6-diaminoresorcinol phosphate, 0.72 represents the phosphorus pentoxide content in the phosphoric acid, and d 0.583 represents 0.72 represents the phosphorus pentoxide content in the 4, 6-diaminoresorcinol phosphate. The denominator of X1 is the sum of (poly) phosphoric acid and phosphorus pentoxide.

X2 is the percentage content of the total phosphorus pentoxide accounting for the solvent after the reaction is finished, the numerator of X2 is the same as that of X1, and the denominator of X2 is the denominator of X1 plus the amount of water generated by the reaction.

For example, when 14kg of polyphosphoric acid (84.5% of P ₂ O ₅ in polyphosphoric acid) and 8.5kg of phosphorus pentoxide are charged, and 5.89kg of phosphate containing 55% of phosphoric acid, X1 is (14 is 0.845+8.5+6.34 is 0.583 is 0.72)/(14+8.5+6.34 is 0.583) is 87.8% and X2 after polymerization is higher depending on the mass of water produced, the higher the degree of polymerization of the polymer, the lower X2.

preferably, the dosage of the polyphosphoric acid is 2-4 times of the mass of the 4, 6-diaminoresorcinol phosphate; the molar ratio of the terephthalic acid to the 4, 6-diaminoresorcinol phosphate is 0.95-1.02: 1.

Preferably, the specific steps are as follows: adding polyphosphoric acid and phosphorus pentoxide into a reaction bottle under the protection of nitrogen, stirring, heating to obtain a mixed medium, adding 4, 6-diaminoresorcinol phosphate and terephthalic acid, then preserving heat at 100-120 ℃ for 1-4 h, preserving heat at 120-150 ℃ for 1-4 h, preserving heat at 150-170 ℃ for 0.2-2 h, and finally preserving heat at 170-185 ℃ for 2-6 h to obtain the poly (p-phenylene-benzobisoxazole).

Preferably, the temperature of the polyphosphoric acid and the phosphorus pentoxide is 100-120 ℃, and the mixture is stirred for 0.2-2 hours.

Preferably, the terephthalic acid is pretreated before reaction, and the pretreatment method comprises the following steps: and (3) grinding for 3-4 h by using a stainless steel ball mill under the condition of 600 r/min. The terephthalic acid (TPA) particles obtained after pretreatment are relatively fine, which is beneficial to the polymerization.

Preferably, the 4, 6-diaminoresorcinol phosphate is prepared by the following method: adding 4, 6-dinitroresorcinol, a solvent and a catalyst into an autoclave, reacting at the temperature of 40-60 ℃ and under the pressure of 0.2-1.0 MPa, filtering and recovering the catalyst under the protection of nitrogen after the reaction is finished, dropwise adding the filtrate into a phosphoric acid aqueous solution, fully stirring, and performing post-treatment to obtain the 4, 6-diaminoresorcinol phosphate.

preferably, the solvent is any one of methanol, ethanol, methanol/DMF, dioxane and sodium hydroxide aqueous solution, and the using amount of the solvent is 6-12 times of the mass of the 4, 6-dinitroresorcinol.

Preferably, the catalyst is Raney nickel or 1-10% palladium carbon or 1-10% platinum carbon, and the amount of the catalyst is 1-10% of the mass of 4, 6-dinitroresorcinol.

Preferably, the preparation method of the poly-p-phenylene benzobisoxazole fiber comprises the following steps:

(1) Adding 20g of 4, 6-dinitroresorcinol, 200ml of methanol and 1.0g of 5% palladium carbon into a 500ml high-pressure kettle, sealing the reaction kettle, replacing nitrogen and hydrogen for 5 times respectively, slowly heating to 45 ℃, introducing hydrogen to 0.3MPa, preserving heat for 1.5h under the condition, heating to 55 ℃ and 0.8MPa, continuing to react until the pressure is unchanged, continuing to preserve heat for 0.5h, stopping the reaction, filtering out a catalyst while the catalyst is hot under the protection of nitrogen, dropwise adding the filtrate into a 20% phosphoric acid aqueous solution, fully stirring, cooling the filtrate for crystallization, filtering to obtain a 4, 6-diaminoresorcinol phosphate crude product, pulping the crude product by using a 0.5% stannous chloride methanol solution, filtering, and drying in vacuum to obtain the 4, 6-diaminoresorcinol phosphate with the purity of more than 99.5%;

(2) Adding 14g of 84.5% polyphosphoric acid and 8.5g of phosphorus pentoxide into a reaction bottle, starting stirring under the protection of nitrogen, heating to 110 ℃, preserving heat for 0.5h, adding 6.34g (18.9mmol, the content of phosphoric acid is 58.3%) of 4, 6-diaminoresorcinol phosphate and 3.10g (18.6mmol) of terephthalic acid after heat preservation, then preserving heat for 2h at 110 ℃, 2h at 135 ℃, 1h at 160 ℃, and finally 3h at 180 ℃ to obtain PBO (poly (p-phenylene benzobisoxazole)) pre-polymerization liquid;

(3) And (3) carrying out wire drawing on the obtained prepolymerization solution, washing the obtained fiber with water, then washing with weak alkaline water, then washing with clear water, and finally drying by blowing to obtain the poly (p-phenylene benzobisoxazole) fiber with eta of 32.3.

the invention achieves the following beneficial effects:

1. The invention adopts 4, 6-diamino resorcinol phosphate (DARP) and terephthalic acid (TPA) for polymerization, thereby not only saving the time of dehydrochlorination gas, but also greatly reducing the requirements on equipment (hydrogen chloride does not need to be removed at high temperature);

2. The invention adopts the mixed reaction medium of polyphosphoric acid and phosphorus pentoxide to control the content of the dioxygen pentoxide, so that the prepared PBO has high polymerization degree and is suitable to be used as a raw material for industrial production;

3. The invention adopts the pretreated terephthalic acid (TPA), which can greatly reduce the polymerization time;

4. Provides a preparation method of 4, 6-diamino resorcinol phosphate with high product purity.

drawings

FIG. 1 is an infrared spectrum of 4, 6-diaminoresorcinol phosphate obtained in example 1;

FIG. 2 is a nuclear magnetic resonance hydrogen spectrum of 4, 6-diaminoresorcinol phosphate obtained in example 1;

FIG. 3 is an infrared spectrum of a polyparaphenylene benzobisoxazole fiber obtained in example 1.

Detailed Description

The present invention is further described with reference to the following specific examples, which are not intended to be limiting, but are intended to be exemplary only in light of the teachings of the present invention and are not intended to be limiting.