A method of obtaining a high-strength fiber

 

(57) Abstract:

High-strength fibers based on aromatic depolimerization (ABI) used in organoplastic aerospace, defense and other purposes. Obtaining high-strength fiber includes the introduction of polyvinylpyrrolidone in solution polycondensation of aromatic copolyamid in dimethylacetamide, molding him into the precipitation bath, washing, drying and heat treatment. At the same time as aromatic copolyamid use depolyarizatsiya received low-temperature mortar polycondensate in a mixture of dimethylacetamide and lithium chloride from 100% terephthaloylchloride, 70 mol.% 5(6)-amino-2-n-aminobenzimidazole and 30 mol.% n-phenylenediamine, and polyvinylpyrrolidone is administered in an amount of 5 to 1 wt.%. The resulting fiber has a high ishibashiiwata and, therefore, increased resistance to axial compression of PABI. 1 C.p. f-crystals, 1 tab., 1 Il.

The invention relates to the field of production of high strength fibers based on aromatic depolimerization (ABI) used, usually in organoplastic aerospace, defense and other purposes.

It is known that high strength is an order of magnitude lower than the tensile strength, which limits the use of synthetic reinforcing fibres in organoplastic main destination.

In the patent of Russian Federation N 2017866, 1994 described high-strength fibers on the basis of PABI different chemical structures and methods for their production, but data on compressive strength or ishibashiiwata fibers are absent.

A method of obtaining high-strength fibers of a mixture of podi-p-phenyleneterephthalamide (PPTA) and polyvinylpyrrolidone (PVP) through a common solvent (100% sulfuric acid), described in the patent to DuPont. Data ishibashiiwata these threads are missing (EP 0396020, 1990).

The closest technical solution is a method for fibrous materials from a mixture of PVP and aromatic copolyamids complex structure that includes parts of three diamines and terephthalic acid, with the content of PVP from 7 to 70% (preferably 45-55%).

However, data on ishibashiiwata thread and compressive strength are also missing (2024654, 1994).

The technical purpose of this invention is to improve ishibashiiwata and, consequently, the strength to axial compression of PBI fibers, as well as their cost reduction without loss of strength.

P in dimethylacetamide (DMAA), at the same time as aromatic copolyamid use BABY received low-temperature solution polycondensation in a mixture of dimethylacetamide and lithium chloride from 100 mol.% terephthaloylchloride, 70 mol.% 5(6)-amino-2-n-aminobenzimidazole and 30 mol.% n-penitenziaria, and polyvinylpyrrolidone enter in the amount of 5-10 wt. %. In addition, heat treatment is performed at 350oC. Diamines in the number 9,92 and 2,05 g respectively dissolved in 464 ml DMAA containing 3% lithium chloride. After dissolution of the diamines, the solution is cooled to 8oC with constant stirring 12,64 g (0,0623 M) terephthaloylchloride for 55 minutes the viscosity of the solution thus gradually increases and after additional stirring at 20-22oC for 1.5 h is 500-600 P.

In the resulting solution was injected different amounts of PVP, after dissolution which at room temperature of the spinning solution was filtered and obezvozhivani. Thread got wet molding through the die plate 100/0,1 (100 holes with a diameter of 0.1 mm) in the horizontal precipitation bath of 55-60% aqueous solution DMAA at 20oC speed 3-13 m/min with a negative spunbond hood. After molding the fiber thoroughly prospect the 50oC for 30 minutes

The table shows the characteristics of solutions and mechanical properties of yarns.

The table shows that:

the concentration of the spinning solution of a mixture of polymers with the introduction of PVP in them to 20% almost completely corresponds to the estimated total presence of both polymers. Since it was determined by the gravimetric method on planting the film with water, it shows the full deposition PVP together with BABY and, consequently, the formation of interpolymer complex of these polymers. All planted films are transparent, which also indicates the compatibility PVP with BABY.

- increase the viscosity of the spinning solution with the introduction of PVP may also indicate a strong intermolecular interaction of PVP with PABI;

for heat-treated fibers high strength properties are maintained up to 10% PVP in the mixture of polymers, although in absolute terms the strength will degrade somewhat. Given that PVP is not fibre-forming polymer and to calculate relative strength composite fibers with this in mind, the strength and 10% PVP content is not lower than for PBI fibers;

linear density mixed n which there is partial destruction PVP and the removal of the degradation products from the fiber. Indeed, according to X the content of PVP in the mixed fibers was slightly reduced after heat treatment, but not less than 70% of the original amount of this polymer remains in the fiber;

- shimonthebest threads when introducing PVP only 5% increases almost two times;

It should be noted that PVP is much cheaper BABY and its Supplement in the amount of 5-10% in high-strength fiber contributes to a significant reduction of this fiber.

The dependence of the strength of the initial and heat-treated mixed threads from the number of admixtures on the graph below. On the vertical axis indicated the strength in CN/Tex. On the horizontal axis - wt.% the injected polymer.

The graph presents the following notation:

x - PVP;

about a copolymer of caprolactam and salt AG;

- poly-m-phenylenedimaleimide;

- copolyamide m-phenylenediamine and a mixture of Tere - and isophthalic acid (40: 60);

- PVC.

As can be seen from the accompanying graph, unlike other PVP investigated additives lead to a sharp decrease in the strength of heat-treated fibers, although the strength of the freshly formed threads for all additives remain at the same level. Planted from the spine flexible-chain aliphatic and aromatic polyamides with BABY.

1. A method of obtaining a high-strength fiber, including the introduction of polyvinylpyrrolidone and solution polycondensation of aromatic copolyamid in dimethylacetamide, molding him into the precipitation bath, washing, drying, heat treatment, characterized in that the aromatic copolyamid use depolyarizatsiya received low-temperature solution polycondensation in a mixture of dimethylacetamide and lithium chloride from 100 mol.% terephthaloylchloride, 70 mol.% 5(6)-amino-2-n-aminobenzimidazole and 30 mol. % n-phenylenediamine, and polyvinylpyrrolidone is administered in an amount of 5 to 10 wt.%.

2. The method according to p. 1, characterized in that the heat treatment is performed at 350oC.

 

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