Preparation method of PBO

Abstract

A preparation method of PBO which comprises the following steps: dispersing and mixing the following raw materials: 4,6-diamino-1,3-resorcinol hydrochlorate or phosphate, terephthalic acid, polyphosphoric acid and phosphorus pentoxide at the temperature of 60 to 150 DEG C; degassing under a vacuum circumstance; carrying out polymerization reaction of the mixture in a capillary microfluid reaction space of which the pipe diameter is 1 to 10 mm by passing the mixture through at least three reaction zones in a warmer and warmer manner, wherein the temperature range of 100 to 200 DEG C, the temperature difference of adjacent reaction zones is equal to or higher than 40 DEG C, and the intrinsic viscosity of the obtained PBO end product is 20 to 30 dl / g. Through high efficiency and uniform heat transmission and mass transfer, the temperature in the polymerization reaction system is uniform, the controllability is higher, and polymerization reaction can be carried out and fulfilled efficiently; under the premise of the same polymer molecular weight, the polymerization reaction time can be shortened to several hours, or even dozens of minutes; both the production efficiency and heat efficiency are greatly improved.

Description

technical field [0001] The present invention relates to a new preparation method of PBO (poly-p-phenylene benzobisoxazole). Background technique [0002] PBO fiber is currently the material with the highest tensile strength and tensile modulus among organic synthetic fibers, and it is also the synthetic material with the best heat resistance and stability. Its thermal decomposition temperature is as high as 600°C. It has great application prospects in aerospace, military industry, cable, fire protection, industrial composite materials and industrial fields. The structure of PBO is shown in formula (I), in which the number average degree of polymerization of n is generally 40-80, and 50-65 is more preferable. [0003] [0004] The synthesis of PBO fiber mainly uses monomers such as diaminoresorcinol hydrochloride or phosphate, terephthalic acid or terephthaloyl chloride to carry out high-temperature polycondensation in polyphosphoric acid medium to obtain spinning solut...

AI Technical Summary

Problems solved by technology

Although this method solves the problem of batching to a certain extent, its polycondensation reaction time is still very long. The monomer is treated in a polyphosphoric acid medium at 95°C for 32 hours, and then compressed and polymerized at 190°C for 24 hours. Still not ideal, intrinsic viscosity is only 14.5dl / g (25°C, 0.0528g / dl methanesulfonic acid solution)

[0009] The study found that the main problem of the above method is that the terephthalic acid used in the polycondensation process is not soluble in polyphosphoric acid, and the 4,6-diamino-1,3-resorcinol hydrochloride monomer needs to be dissolved in the polyphosphoric acid. Hydrogen chloride is completely removed in high-viscosity polyphosphoric acid medium, degassing and polycondensation reaction speed is slow, polycondensation reaction time is long, polymerization reaction is not complete (heterocyclic ring closure is incomplete)

At the same time, due to the high viscosity of the system in the later stage of polymerization, the effects of stirring, heat transfer and mass transfer are not ideal, which seriously affects the later stage of polymerization.

To achieve the corresponding degree of polymerization, it takes a very long time, the production efficiency is low, and even after the required degree of polymerization is reached in the reactor, it is very difficult to transport due to the high viscosity of the system

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