KR910004472B1 - Manufacturing process of metamorphosis polyester fibers - Google Patents

Abstract

The modified polyester fiber is prepd by the steps: (a) ester exchanging reacting or directly estorifying reacting 1-5 mol% of the cpd. contg. sulphate gp. of metal salts and ester bond forming gp.p (b) pre-polycondensating; and (c) polycondensating that to prepare the polyester copolymer at 250-320 deg.C; (d) melt-spinning; (e) drawing that with 85-95% drawing ratio of the fine drawing yarn; then (f) heat-treating between to the cristalising temp. and 20 deg.C below of the melting temp. of the polyester.

Description

Method for producing modified polyester fiber

The present invention relates to a method for producing a modified polyester fiber exhibiting excellent shrinkage properties and good morphological stability and salting to basic dyes.

The present invention improves the conventional technique of copolymerizing a metal sulfoisophthalic acid component to improve the dyeability of polyester fibers, so that the dye can be easily dyed with a basic dye and exhibits excellent shrinkage characteristics, and thus the mechanical properties of the fiber change over time. It is an object of the present invention to provide a method for producing a modified polyester fiber.

Polyester, especially polyethylene terephthalate, has excellent mechanical and chemical properties and is widely used as a medical fiber and an acid fiber.

By the way, since polyethylene terephthalate fiber has the disadvantage that it is poor in dyeability, the method of improving dyeability is conventionally proposed in various ways. The most typical method is a method of copolymerizing a metal sulfur isophthalic acid component to polyester to impart salting property to a basic dye (Public Works No. 34-10497). However, when imparting salting resistance to basic dyes by this method, no particular problem is found in general medical use, but high-value-added silcides, irregularities, and irregularities that impart sublimation, drape, etc. due to heat shrinkage When applied to brushed fabrics and knitted fabrics for the purpose of twill effect, the boiling shrinkage rate and dry heat shrinkage rate are remarkably low, and when the shrinkage rate is improved by the conventional method of expressing high shrinkage (Spec. 59-112025), There is a limit to obtaining the required effect by causing a change in mechanical properties.

The present invention solves the above problems as described in detail below.

That is, the present invention, in the preparation of fiber-forming polyethylene terephthalate from terephthalic acid or its esters and ethylene glycol, 1-5 mol% of a compound sharing an ester bond-forming group with a sulfonate group in the form of a metal salt and terephthalic acid or an ester thereof Copolymerized polyester copolymerized with addition of 5-10 mol% of aromatic dicarboxylic acid or its ester was spun through a conventional melt spinning machine, and then stretched at a draw ratio of 85% -95% of the undrawn yarn breaking elongation. Stretched and heat-treated at a temperature of less than 20 ℃ than the melting point and the crystallization temperature of the copolymer, the modified polyester fiber produced by the above method has the following characteristics.

Below

A) Cutting elongation: 40% or less

B) sinus shrinkage: more than 65%

C) Dry heat shrinkage (180 ℃, 15 minutes): 60% or more

D) Maintenance rate of dry heat shrinkage after 6 months under standard condition: over 99%

Terephthalic acid or esters thereof in the present invention are esters of monohydric alcohols having 4 or less carbon atoms and terephthalic acid, and a representative example thereof is dimethyl terephthalate. In addition, 5-metalsulfur isophthalic acid and ester-forming derivatives such as lower alcohol esters and lower glycol esters are used as compounds which share an ester-forming group with a sulfonate group having a metal salt form. Alkali metals, such as K, are preferable.

In the present invention, the amount of the compound sharing the sulfonate group and the ester-forming group in the form of a metal salt is 1-5 mol% with respect to terephthalic acid or esters thereof, and in particular, the range of 2-4 mol% is most suitable. This is determined from the basic dye dyeing property and the product properties of the polyester fiber produced. If 1 mol% or less is insufficient for basic dye dyeing, and 5 mol% or more is co-polymerized, a sulfonate group having a metal salt form Due to the central action, the melt viscosity increases rapidly during spinning, making spinning difficult in a conventional manner.

In addition, when the selected compound does not have one ester bond forming group in the molecule, a polymer having a satisfactory degree of polymerization cannot be obtained. In this case, it is preferable to add a small amount of a chain branching agent having three or more ester bond forming groups. . Compounds usable as chain branching agents are benzenetricarboxylic acids, benzenetetracarboxylic acids, and trivalent or higher polycarboxylic acids and polyols, such as such lower dialkyl esters, trimethyl ylpropane and pentaerythritol.

In the present invention, the following compounds are used as aromatic dicarboxylic acid or its ester except terephthalic acid or its ester,

Below

The amount of the compound added is 5-15 mol%, particularly 8-12 mol%, relative to terephthalic acid or its ester. When 5 mol% or less is added and used, it is difficult to give the shrinkage characteristics desired in the present invention. When 15 mol% or more is added and copolymerized, the crystal structure is severely broken, so that the strength of the yarn is markedly deteriorated and practical operation is impossible.

In the present invention, a compound which shares an ester bond-forming group with a sulfonate group in the form of a metal salt, and an aromatic dicarboxylic acid or ester thereof except terephthalic acid or an ester thereof is used to complete the synthesis of polyethylene terephthalate from terephthalic acid or an ester thereof with ethylene glycol. In any step, addition copolymerization. In order to obtain a product under the high pressure to be added, it is particularly preferred to be added before, after or in the middle of the esterification reaction or the transesterification reaction.

In this way, the co-polyester which completes the synthesis reaction by transesterification or direct esterification followed by precondensation reaction and polycondensation at 250 ° C.-320 ° C., especially 260 ° C.-290 ° C., is made into chips and then melted conventionally. Spin through a spinner and draw and heat treatment as described below.

That is, the copolyester is spun through a conventional melt spinning machine, and then stretched at a draw ratio of 85% or more of the spun undrawn yarn elongation, and heat treatment is performed at a temperature above the crystallization temperature of the polymer.

In more detail, the copolyester non-drawn yarn is drawn at a draw ratio of 85% -95% of the undrawn yarn elongation to increase the crystallinity and orientation of the fiber and between 20 ° C. below the crystallization temperature and the melting point of the copolymer. By heat treatment at temperature, it gives thermal stability, elongation of 40% or less, boiling shrinkage of 65% or more, dry heat shrinkage (180 ℃, 15 minutes) of 60% or more. It is to prepare a basic dye saltable modified polyester. When stretching the copolyester unstretched yarn of the present invention at a draw ratio of 85% or less of the unstretched yarn elongation, the crystallinity is lowered and there is a partial unstretched portion, which leads to a decrease in strength, saltiness, and salt tea. The orientation of the region is also lowered, which does not exhibit sufficient shrinkage characteristics, and when drawn at a stretching ratio of 95% or more, there is a limit in improving the shrinkage rate due to the relative decrease of the amorphous region due to the increase of the crystal region.

In addition, when the copolymer is heat-treated at a temperature below the crystallization temperature of the copolymer, the intermolecular bonds in the fiber are thermally loosened, so that the distance between the bonds is shortened and the binding energy is low, so that deformation occurs easily at low temperatures, resulting in poor morphological stability and lower than the melting point. At a temperature not lower than 占 폚, flow and fusion of the seal occur, resulting in poor operation. As described above, the present invention provides basic dye salting by copolymerizing an aromatic dicarboxylic acid or an ester thereof with an appropriate amount of a compound having an ester forming group and a sulfonate group having a metal salt form during polymerization of polyethylene terephthalate. While appropriately suppressing crystallization, the film is stretched at a draw ratio of 85% to 95% of the undrawn yarn elongation during the stretching process to impart the unique mechanical properties of the polyester to the crystallization temperature of the copolymer and a temperature of less than 20 ° C. above the melting point. It is a method of imparting thermal stability and shape stability by heat treatment.

Example 1

100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, 3.8 parts of 5-sodium sulfisoisophthalic acid, 8 parts of dimethyl isophthalate, 0.015 parts of zinc acetate and 0.04 parts of antimony trioxide were placed in an autoclave equipped with a rectifying tower to discharge the produced methanol. While stirring and heating at 180 ℃ -230 ℃ for 2 hours and 30 minutes to remove more than 97% of the theoretical amount of methanol, add 0.5 parts of titanium oxide, transfer the reaction product to autoclave for reduced pressure, add 0.03 parts of phosphorous acid, and add 280 ℃, The polymerization was continued for 2 hours in a vacuum of 0.5 mmHg or less, and then extruded into plates and cut into granules to obtain a polymer having a melting point of 230 ° C. and an intrinsic viscosity of 0.66. The copolymer was extruded through 24 spinnerets at a melting temperature of 275 ° C. and wound at a rate of 1800 m / min to prepare undrawn yarn. The resultant was drawn at a draw ratio of 89% of the obtained undrawn yarn cut elongation, followed by heat treatment at 170 ° C. To obtain physical properties as shown in Table 2.

Comparative Example 1-4

A 5-sodium sulfoisophthalic acid component and dimethylisophthalate are used in the same manner as in Example 1 except that Table 1 is used.

Comparative Example 5-8

The undrawn yarn obtained in the same manner as in Example 1 is stretched under the conditions shown in Table 1. The water politics of Table 2 were measured by the following method.

1) Intrinsic Viscosity: It was measured at 20 ° C. using an equiweight mixture of phenol and ethane tetrachloride.

2) a boiling shrinkage ratio: 0.1g / d of a sample sheet under load of the L ₁ and removal of the load, and then were treated for 30 minutes in boiling water, and a length L measured under the same load as the boiling shrinkage ratio by the following equation of Obtain

3) Dry heat shrinkage: The length of the sample under the load of 0.1g / d is L ₁ , the load is removed, and the sample is treated at 180 ° C for 15 minutes in a drying oven, and the length measured under the same load is L. The dry heat shrinkage rate is obtained by

4) Dry heat shrinkage retention rate: After measuring the dry heat shrinkage rate H ₁ , store it for 6 months in a standard state, and then measure the dry heat shrinkage rate H again to obtain the dry heat shrinkage rate according to the following equation.

TABLE 1

Addition amount and drawing condition

Where A: amount of 5-sodiumsulfurisophthalic acid added

B: Addition amount of dimethyl isophthalate

TABLE 2

Properties

Claims (3)

In preparing a fiber-forming polyethylene terephthalate from terephthalic acid or its ester and ethylene glycol, 1 to 5 mol% of a compound sharing an ester bond-forming group with a sulfonate group in the form of a metal salt and an aromatic dicarboxylic acid or terephthalic acid or an ester thereof is excluded. 5-10 mole% of ester is subjected to transesterification or direct esterification and pre-condensation reaction, followed by melt spinning the copolyester prepared by polycondensation at 250-320 ° C. A method for producing a modified polyester fiber, which is stretched at a draw ratio of and subsequently heat treated at a temperature between 20 ° C. below the crystallization temperature and the melting point of the copolyester. The method for producing a modified polyester fiber according to claim 1, wherein the compound which shares a sulfonate group and an ester forming group in a metal salt form is 5-sodiumsulfur isophthalic acid. The method of producing a modified polyester fiber according to claim 1, wherein the aromatic dicarboxylic acid or ester thereof except terephthalic acid or ester thereof is dimethylisophthalate.