SU960326A1 - Method for regenerating solvent in synthetic fiber manufacture - Google Patents

Description

This invention relates to the production of synthetic fibers obtained by spinning into a precipitation bath containing an organic solvent of a polymer, an inorganic salt, and a precipitant.

In order to maintain a constant, predetermined composition, a portion of the precipitation bath (spent precipitation panna) is diverted to the regeneration of the components.

A known method for the regeneration of components from a used precipitation bath / containing 30-80% solvent, 1-10% inorganic salt, and 20-70% precipitator by distillation at a pressure of 7-10 IJ04 mercury. Art. and a temperature of 200 ° C to a residue. The mixture of solvent and precipitant is divided into its constituent components by rectification. The dry residue — an inorganic salt contaminated with iron compounds — is subjected to long-term purification. To remove the iron compounds, the dry residue is dissolved in water and the resulting solution is alkalinized. The precipitated iron hydroxide is filtered off, and the aqueous solution of the inorganic salt is evaporated, cris. gallant and dry. To remove organic impurities (residues of solvent, precipitator, polymer, their decomposition products), the dried inorganic salt is calcined at 400-450 s. The regenerated components are used to prepare the composition of the polymer solvent and to update the precipitation bath 1.

The main disadvantages of this method of regeneration are the cumbersomeness of the technological scheme, the complexity of the hardware of Shani, and the high energy costs.

Closest to the invention

15 is a solvent recovery method in the production of synthetic fibers from a precipitation bath containing a polymer solvent, a precipitant and an inorganic salt, by distillation

20 until the precipitant is completely removed and the bottom residue is returned to a saturated solution of the inorganic salt in the production process, the bottom residue is preliminarily crystallized at

The resulting complex salt is directed to the preparation of a polymer solvent composition. Uterine solution

The 30 grams of complex polluted iron compounds remaining after crystallization are removed from the process and sent to the destruction of f2.

The process is characterized by a low yield of the regenerated components. The loss of the inorganic salt is 40–45%, and that of the solvent is 10–25% of the amount fed to the regeneration,.

The stage of obtaining the complex salt is technologically complex and requires expensive and complex equipment. Frequently, crystallizers with enamel coating quickly come out of the system, due to the large temperature gradient (up to 95 ° C) during crystallization of keZ, mg 1 of x salt: salt. Complex salts form persistent supersaturated solutions, so even small deviations in the crystallization mode result in either a full crystallization of the-solution in the crystallizer or the formation of fine crystalline suspension, which is difficult to separate from the mother liquor, or the crystallization of complex salt with a high content of contaminants. .

The purpose of the invention is to increase the yield of the product, increase its quality, simplify the process.

The goal is achieved in that according to the method of solvent regeneration in the production of synthetic fibers from a precipitation bath containing a polymer solvent, a precipitator and an inorganic salt, by distillation at -10 ° C until the precipitator is completely removed and the vat residue is returned to a saturated solution The real process is that a substance selected from the group comprising: ethyl acetate, diethyl ether, methylene chloride, metaxylene, heptane, is added to the residue: 1: (0.12-13), the fallen osa is separated. and the substance is distilled off.

Example. Settlement bath of composition: DMAA 37.5%; isobutyl alcohol (CHD) 61.4%; LiCl (I) 1.1%; 5 mg / kg is distilled under vacuum. From 100 kg of bath, 84.28 kg of distillate of composition are formed: kg (72.85%) of IHD and 22.88 (27.15% of DMAA sent to upgrade the sedimentation bath, and 15.72 kg of the bottom residue of composition: .14 , 62 kg (93.00%) DMAA; 1.1 kg (7.00%) I and 31.8 mg / kg Fe. Add ethyl acetate (EA) to the bottom residue in relation to the bottom residue of 0.28 1 (4.34 kg.) The precipitate formed is separated from the liquid phase by filtration. A solid weighing 0.1005 kg containing 0.016 kg (15j92%) I; 0.075 kg (74.63%) DMAA; 0.009 kg

(8.95%) EA and 0.0005 kg (0.50%) are sent for disposal. The filtrate (19.96 kg) containing 14.545 kg (72.87%) DMAA; 4.331 kg (21.70%) EA; 1.094 kg (5.43%) was distilled to distill off ethyl acetate. The cube residue of composition 14.065 kg (92.78%) DMAA; 1.084 kg (7.15%) I and 0.011 kg (0.07%) EA are returned to prepare the polymer solvent composition. A distillate (4.8 kg), consisting of 4.32 kg (90.0%) EA and 0.48 kg (10.0%) DMAA, is returned to the extraction. Losses I are 1.45%, and DMAA - 0.2%. Regenerated products do not contain iron compounds.

; Pr e-M e. P 2 .. Precipitation bath composition: dimethylformamide (DMF) 60.00%; , water is 38.50%; CaCi (II) 1.50%, 1 mg / kg is distilled under vacuum. 55.38 kg of distillate of the composition: 38.5 kg (68.90%) of water and 17.38 kg., (33.1%) of DMF sent to renew the sedimentation bath, and 44.12 kg VAT residue composition: 42,62- kg (96.60%) DMF; 1.5 kg (3.40%) II and 22.67 mg / kg Fe-. 9.44 kg of diethyl ether (ECD) (ratio with bottom residue, .0.21: 1) is added to the bottoms residue. The resulting suspension is separated by filtration. Sediment weighing 0.157 kg, containing 0.12 kg (76.43%) DG-1FA; 0.03 kg (19.10%). 11; 0.006 kg (.3, 82%) DEE and 0.001. Kg (0.65%) of Fe sent for destruction, the filtrate (53.404 kg) containing 42.50 kg (79.58%) of DMF; 9.43 kg (17.66%) of ECD and 1.47 kg: (2.76%) II. Distillate distillation to distill DZE. The bottom residue (43.577 kg), CONTAINING of 42.107 kg (96.63%) of DMF and 1.47.kg; (3.37%) II, is returned to production. The distillate is G9.827 kg) containing 9.434 kg (96.00%) DEE and 0.393 kg (4.00%) DMF is sent to the cleaning stage of corrosion products. The loss of DMF is 0.2%; II - 2.0%. Regenerated products do not contain iron compounds.

Example 3. Used precipitation bath composition; 80.00% DMF 16.00% water; 4.00% LiCl. (I) and 10 mg / Fe 3, distilled under vacuum. 27.27 kg of distillate of the composition was distilled off from the bath: 16 kg (58.67%) of water and 11.27 kg (41.33%), which was sent for renewal of the wax bath, and formed 72.73 kg of cube residue composition: 68.73 kg (94.50%). DMF; 4.00 kg (5.50%) I and 13.75 mg / kg Fe. 945 49 kg of methylene chloride (MX) are added to the bottom residue (13: 1 ratio to the bottom residue). The resulting suspension is separated by filtration.

Claims (1)

Claim The method of solvent regeneration in the production of synthetic fibers from a precipitation bath containing a polymer solvent, a precipitant and an inorganic salt, by distillation at 60-100 ° С until the precipitator is completely removed and the bottom residue of a saturated solution of inorganic salt in the solvent is returned to the production process, about t and h and the fact that, in order to increase the yield of the product, improve its quality, simplify the process, a substance selected from the group consisting of ethyl- is additionally introduced into the bottom residue. acetate, diethyl ether, methylene chloride, l-xylene, heptane, in a ratio of 1: (0.12-13), the precipitate formed is separated off, and this substance is distilled off.