KR0160477B1 - Process for preparing modified polyester having excellent hydrolysis resistance at alkali solution - Google Patents

Abstract

The present invention relates to a method for producing a modified polyester which is used to prepare a synthetic fiber microfiber and excellent in hydrolysis in an aqueous alkali solution, wherein the compound of the following general formula (2) is 2 to terephthalic acid or dimethyl terephthalate during polymerization of the polyester. 5 mol%, the compound of the formula (1) is 50 to 150% by weight based on the compound of the formula (2) to polymerize, the melt viscosity is reduced, the occurrence of trimming during spinning is reduced.

(In the above, R ¹ and R ² are alkyl groups and n is an integer of 10-50.)

(In the above, R ³ , R ⁴ are each H, CH ₃ , CH ₂ CH ₂ OH group.)

Description

Method for producing modified polyester having excellent hydrolysis property in alkaline aqueous solution

The present invention relates to a method for producing a polyester-based material that is easily hydrolyzed in an aqueous alkali solution, and more particularly, fiber-forming polyamide and polyester, or polyester and polyester-based component in the production of synthetic fiber microfiber The present invention relates to a method for producing a water-soluble modified polyester having excellent hydrolyzability in an aqueous alkali solution as a dissolving component.

In general, as a method for producing a synthetic fiber microfiber, as shown in Japanese Patent Laid-Open No. 55-172423, a fiber-forming polyamide resin and a fiber-forming polyester resin are alternately arranged to produce a composite fiber. There is a technique of manufacturing a microfiber by weaving and knitting using this, followed by micronization through physical and chemical separation. However, when the ultrafine composite fibers thus prepared are separated by weaving or knitting, there are many difficulties in uniform dyeing due to the incomplete separation of the two components, and due to the difference in the dyeing characteristics of the coexisting polyamide and polyester systems. In addition, there is a big problem such as the troublesome process of performing dyeing in two steps and a decrease in color fastness.

In order to solve this problem, a method of dissolving and removing one of the two components has been proposed in Japanese Patent Laid-Open Nos. 59-130361, 56-37332, and 55-116874, which are polyolefin resins and modified polyester resins. And modified polyvinyl alcohol and polystyrene are used. Among them, polyolefin and polystyrene have to be dissolved in an organic solvent, which leads to a complicated process, and polyvinyl alcohol has a disadvantage in that it is difficult to manage moisture content during the spinning process. The modified polyester system which dissolves in aqueous solution is mainly used. As the modified polyester used, a method of copolymerizing 1-10 mol% of isophthalic acid component containing sodium sulfonate group reactive to ethylene glycol with respect to terephthalic acid or dimethyl terephthalate component was mainly used. However, in the case of producing a microfiber composite yarn by mixing with a general polyester using the modified polyester manufactured by the above, in order to completely hydrolyze the modified polyester, the melt viscosity (Melt Viscosity) is more than that of the general polyester. It was difficult to obtain a modified polyester of high polymerization degree because of high.

As a method for solving this problem, there is a method of lowering the content of the isophthalic acid component containing sodium sulfonate group, but in this case, it is difficult to obtain a satisfactory dissolution rate for the aqueous alkali solution.

Therefore, a technique for producing a modified polyester having a high hydrolysis rate with respect to an aqueous alkali solution while not having a high melt viscosity has been a problem.

Accordingly, the inventors have found that the hydrolysis rate of the modified polyester in aqueous alkali solution is related to the content of sodium sulfonate group, and thus the present invention was devised by introducing and using a compound containing sodium sulfonate group in the modified polyester polymerization.

That is, the present invention is a polystyrene containing the compound of the general formula (2) to be 2-5 mol% of telephthalic acid or dimethyl terephthalate during the polyester polymerization, and also contains the sodium sulfonate group of the general formula (1) The present invention is to provide a method for producing a modified polyester, characterized in that the copolymerization by adding 50 to 150% by weight to the isophthalic acid compound containing sodium sulfonate group of the general formula (2).

(Wherein R ¹ and R ² are alkyl groups, n is an integer of 10-50)

(In the above, R ³ , R ⁴ are H, CH ₃ , CH ₂ CH ₂ OH groups, respectively.)

The present invention is a polystyrene compound containing a sodium sulfonate group, which is non-reactive in formula (1), and sodium sulfonate in formula (2) in preparing polyester by polymerizing conventional ethylene glycol with terephthalic acid or dimethyl terephthalate. The isophthalic acid compound containing group is further copolymerized to obtain a modified polyester.

In the present invention, it is not preferable to use only the polystyrene compound containing the non-reactive sodium sulfonate group of the general formula (1) because of the high rate of trimming during the sacrifice of the polymerized modified polyester, and the sodium sulfonate group of the general formula (2). This problem is eliminated when only one isophthalic acid is used together.

In the present invention, the isophthalic acid component containing the sodium sulfonate group of the general formula (2) is suitably 2-5 mol% based on terephthalic acid or dimethyl terephthalate.

In addition, the content of the general formula (1) is preferably 50 to 150% by weight compared to the compound of the general formula (2), when the content is less than 50% by weight increases the melt viscosity of the modified polyester to achieve the object of the present invention It is difficult, because when it is greater than 150% by weight, trimming occurs during spinning.

The present invention will be described in detail with reference to the following Examples.

How to measure

(1) intrinsic viscosity:

(ηrel) is the ratio of the viscosity of the diluted polyester solution in the solvent (3: 2 mixture of phenol and tetrachloroethane) and the solvent viscosity measured at 25 ° C. and C represents the concentration of polyester in the solvent.

(2) Diethylene glycol (DEG): Pyrolyse the polyester with hydrazine hydrate and measure this by gas chromatography.

(3) Reduction rate (%): Put a polyester fiber sample in a solution of 1 g of sodium hydroxide in 1 liter of water and hold for 30 minutes at 100 ℃ and measure the weight loss ratio.

(4) Electrical resistance: Measured by using an electric resistance measuring instrument of TOA of Japan in constant temperature and humidity room.

(5) Friction band voltage: Measure using Kanebo friction belt voltage meter.

Example 1

While maintaining a polymerization tank containing 10 kg of polyethylene terephthalate oligomer at 260 ° C., a slurry in which 8645 g of terephthalic acid and 3875 g of ethylene glycol were well mixed was added over 6 hours to prepare 20 kg of oligomer, and then 10 kg was transferred to another polymerization tank. The compounds of antimony trioxide 5g and the general formula (2) in the oligomeric (R ^3, R ⁴ -CH ₂ CH ₂ OH) 3 mole percent, the formula (1) compound (n = 20, R ^1, R ² is a methyl group ) Was added at a ratio of 150% by weight to the general formula (2), and the copolymer was prepared at 280 ° C under reduced pressure from 760mmHg to 1mmHg in 1 hour to prepare a modified polyester of the present invention. The obtained polymer was dried in a conventional manner, and then spun at a rate of 1000 m / min at 295 ° C. using a mold having 36 circular spherical holes having a diameter of 0.25 mm. The obtained undrawn yarn was drawn at a drawing speed of 1070 m / min by a heating roller maintained at 80 ° C. and a hot plate kept at 120 ° C. to prepare a drawn yarn of 75 d / f, and the physical properties thereof are shown in Table 2.

[Examples 2 and 3]

To prepare a modified polyester as in Example 1, but to prepare a component ratio as shown in Table 1, respectively, the physical properties are shown in Table 2.

[Comparative Examples 1-4]

The components and the dosages prepared in the same manner as in Example 1 were prepared as shown in Table 1, and Comparative Example 2 was prepared by adding 10 wt% of the compound of formula (1) to polyethylene terephthalate (PET) It is shown together in Table 2.

Claims (1)

In preparing a modified polyester for use in synthetic fiber microfibers, 2-5 mol% of isophthalic acid compound containing sodium sulfonate group of the following general formula (2) in the polymerization of polyester with respect to terephthalic acid or dimethyl terephthalate, A method for producing a modified polyester, wherein the polystyrene compound containing the sodium sulfonate group of 1) is mixed at 50 to 150% by weight based on the compound of the general formula (2). (Wherein R ¹ and R ² are alkyl groups, n is an integer of 10-50) (In the above, R ³ , R ⁴ are H, CH ₃ , CH ₂ CH ₂ OH groups, respectively.)