阅读说明：本技术 一种聚对苯撑苯并二噁唑纤维的工业化生产方法 (Industrial production method of poly (p-phenylene-benzobisoxazole) fibers ) 是由 潘志军 金宁人 顾峰雷 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工业化生产方法,包括下述步骤：(1)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预聚液；(2)预聚液经挤出、纺丝而得到聚对苯撑苯并二噁唑纤维。本发明采用4,6二氨基间苯二酚磷酸盐与对苯二甲酸聚合,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；另外,本发明采用预处理过的对苯二甲酸,可以使聚合时间大幅度下降。(The invention relates to an industrial production method of poly (p-phenylene-benzobisoxazole) fiber, which comprises the following steps: (1) 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 poly (p-phenylene-benzobisoxazole) pre-polymerized liquid; (2) and extruding and spinning the pre-polymerized liquid to obtain the poly-p-phenylene benzobisoxazole fiber. The invention adopts 4, 6-diamino resorcinol phosphate and terephthalic acid for polymerization, thereby not only saving the time of dehydrochlorination gas, but also greatly reducing the requirements on equipment; in addition, the invention can greatly reduce the polymerization time by adopting the pretreated terephthalic acid.)

1. An industrial production method of poly-p-phenylene benzobisoxazole fiber is characterized by comprising the following steps:

(1) 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 poly (p-phenylene-benzobisoxazole) pre-polymerized liquid;

(2) and extruding and spinning the pre-polymerized liquid to obtain the poly-p-phenylene benzobisoxazole fiber.

2. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1, characterized in that: and (2) enabling the prepolymerization solution to sequentially pass through a double-screw extruder, a filter and a spinning assembly, and washing, alkaline washing, drying and winding the obtained tows to obtain the polyphenylene benzodioxazole fibers.

3. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1 or 2, characterized in that: before the polymerization reaction in the step (1), the mass of polyphosphoric acid is set as a, and P in polyphosphoric acid is set as P₂O₅The content of (a) is b, the mass of the supplemented phosphorus pentoxide is c, and the mass of the 4, 6-diaminoresorcinol phosphate is d, so that the mass of X1 (ab + c + d 0.583 0.72)/(a + c + d 0.583) is 87-89%; at the end of the polymerization reaction, X2 ═ (ab + c + d 0.583 × 0.72)/(a + c + d 0.583+ wt (H)₂O)) is 82 to 84%, wt (H)₂O) is the mass of water produced in the polymerization.

4. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1, characterized in that: the dosage of the polyphosphoric acid in the step (1) is 2-4 times of the mass of the 4, 6-diaminoresorcinol phosphate.

5. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1, characterized in that: the molar ratio of the terephthalic acid to the 4, 6-diaminoresorcinol phosphate in the step (1) is 0.95-1.02: 1.

6. the industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1 or 2, characterized in that: the step (1) is specifically 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) pre-polymerized liquid.

7. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 6, characterized in that: the temperature of polyphosphoric acid and phosphorus pentoxide is 100-120 ℃, and stirring is carried out for 0.2-2 h.

8. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 1, characterized in that: the terephthalic acid is pretreated before polymerization reaction, and the pretreatment method comprises the following steps: and (3) grinding for 2-8 h under the condition of 600r/min by using a stainless steel ball mill.

9. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 2, characterized in that: and when the inherent viscosity of the pre-polymerization solution reaches 10-15 dL/g, stopping the polymerization reaction, and preparing the pre-polymerization solution to enter a double-screw extruder.

10. The industrial production method of polyparaphenylene benzobisoxazole fiber according to claim 2, characterized in that: in the step (2), the diameter of a screw of the double-screw extruder is 35-85 mm, the rotating speed of the screw is 5-10 rpm, the temperature is 170-190 ℃, and the extrusion pressure is 3.0-5.0 MPa.

Technical Field

The invention belongs to the technical field of material science, and particularly relates to an industrial production 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 industrial production method of high-strength poly (p-Phenylene Benzobisoxazole) (PBO), which can solve the problem of equipment corrosion and has the advantages of environmental protection, green economy and the like.

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

an industrial production method of poly-p-phenylene benzobisoxazole fibers comprises the following steps:

(1) 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 poly (p-phenylene-benzobisoxazole) pre-polymerized liquid;

(2) and extruding and spinning the pre-polymerized liquid to obtain the poly-p-phenylene benzobisoxazole fiber.

The production method of 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, in the step (2), the prepolymerization solution sequentially passes through a double-screw extruder, a filter and a spinning assembly, and the obtained filament bundle is subjected to water washing, alkali washing, water washing, drying and winding to obtain the polyphenylene benzodioxazole fiber.

The polyphosphoric acid (PPA) of the present invention is both a solvent and a cyclizing agent, but if only PPA is used as a reaction medium, since penta-penta in the polyphosphoric acidThe content of the phosphorus oxide is only 84-86%, and the polymerization degree of the fiber obtained by the reaction is limited; if proper amount of phosphorus pentoxide (P) is additionally added₂O₅) The phosphorus pentoxide can react with the water generated by polymerization to generate phosphoric acid, so that the reaction is favorably carried out rightward, and the polymerization degree and the viscosity of the polymer fiber are improved. Supplemental phosphorus pentoxide (P)₂O₅) The more, the stronger the polymerization ability and the higher the molecular weight of the resulting polymer, but P₂O₅The more the system has excessive viscosity, the more the stirring becomes difficult, and therefore, the control of P in the mixing medium is required₂O₅The content of the phosphorus pentoxide is in an optimal proportion, namely the addition amount of the phosphorus pentoxide is controlled. Preferably, before the polymerization reaction in step (1), the mass of the polyphosphoric acid is a, and P in the polyphosphoric acid is P₂O₅B, the mass of the supplemented phosphorus pentoxide is c, and the mass of the 4, 6-diaminoresorcinol phosphate is d, then

X1 ═ (ab + c + d 0.583 ═ 0.72)/(a + c + d 0.583) 87 to 89%; at the end of the polymerization reaction, X2 ═ (ab + c + d 0.583 × 0.72)/(a + c + d 0.583+ wt (H)₂O)) is 82 to 84%, wt (H)₂O) is the mass of water produced in the polymerization.

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.

The applicant finds that when the addition amount of the phosphorus pentoxide is controlled within the content range, the prepared poly-p-phenylene benzobisoxazole fiber has high polymerization degree and good spinning performance. For example, 14kg of polyphosphoric acid (P in polyphosphoric acid) is added₂O₅84.5%) and 7.5kg of phosphorus pentoxide, and 4.87kg of phosphoric acid containing 58.3%Then X1 ═ (14 × 0.845+7.5+4.87 × 0.583 × 0.72)/(14+7.5+4.87 × 0.583) ═ 87.82%. X2 after polymerization depends on the quality of water produced, and 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.

Preferably, the molar ratio of the terephthalic acid to the 4, 6-diaminoresorcinol phosphate is 0.95-1.02: 1.

preferably, step (1) is specifically: 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 2-8 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, when the intrinsic viscosity of the prepolymerization solution reaches 10-15 dL/g, the polymerization reaction is stopped, and the prepolymerization solution is ready to enter a double-screw extruder.

Preferably, the diameter of a screw of the double-screw extruder in the step (2) is 35-85 mm, the rotating speed of the screw is 5-10 rpm, the temperature is 170-190 ℃, and the extrusion pressure is 3.0-5.0 MPa.

Preferably, the alkali washing is carried out by soaking for 2-5 minutes by using 2-6 g/L of sodium hydroxide aqueous solution.

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

(1) adding 12kg of 84.5% polyphosphoric acid and 6.4kg of phosphorus pentoxide into a reaction kettle, stirring under the protection of nitrogen, heating to 100-120 ℃, preserving heat for 0.5h, adding 4.87kg (the content of phosphoric acid is 58.3%) of 4, 6-diaminoresorcinol phosphate and 2.34kg of pretreated terephthalic acid after heat preservation, then preserving heat for 2h at 100-120 ℃, heating to 120-150 ℃, preserving heat for 2h, heating to 150-170 ℃, preserving heat for 1h, and finally preserving heat for 3h at 170-185 ℃ to obtain PBO (poly (p-phenylene benzobisoxazole) prepolymer solution;

(2) and (2) enabling the prepolymerization solution obtained in the step (1) to enter a double-screw extruder with the diameter of 30mm, the rotating speed of 7rpm and the temperature of 185-195 ℃ for continuous reaction, filtering, then enabling the prepolymerization solution to enter a metering pump, sending the mixture to a spinning nozzle, enabling the temperature of a host machine to be 180-185 ℃, enabling the specification of the spinning nozzle to be 0.2mm multiplied by 256 holes, carrying out circular blowing on a filament bundle coming out of the spinning nozzle by 0.3m/s, enabling the filament bundle to be 75m/s, carrying out water washing and alkali washing (the alkali washing solution contains 4g/L of sodium hydroxide), carrying out water washing, drying (the temperature of an upper roller and a lower roller is 260 ℃), finally winding and spinning to obtain the poly (p-phenylene benzobisoxazole) fiber, and measuring eta by using an Ubbelohde viscometer to be 27.3-35 dL/g, the tensile strength to be 4.8-5.5 GPa, the.

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 present invention uses pretreated terephthalic acid (TPA) to greatly reduce the polymerization time.

Drawings

FIG. 1 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.