KR940011543B1 - Manufacturing process of elastic fiber having an excellent elastic property - Google Patents

Abstract

The highly stretchable elastic yarn is produced by: (a) melt-spinning a polyether-ester block copolymer of polybutylene terephthalate-type polyester as a hard segment and polyoxybutylene glycol-type polyether as a soft segment; (b) heat-treating a monofilament elastic yarn at 10 % elogation rate, and heat-treating it to be at most 40 % shrinkage rate; and (c) drawing it at 20-150 deg.C by 2.0-4.0 times. The high stretch elastic yarn has a good elastic recoverability.

Description

Manufacturing method of high elastic elastic yarn

The present invention relates to a method for producing an elastic yarn that exhibits excellent elongation recovery under high elongation as well as low elongation using a polyether-ester block copolymer, wherein polybutylene terephthalate-based polyester is used as a hard segment and polyoxybutyl Block-copolymerized polyether-esters made of lenglycol-based polyethers as soft segments are melt-spun and heat-treated under an elongation of 20% or less, followed by relaxation heat treatment. The present invention relates to a method for producing an elastic yarn, characterized in that the stress is reduced, the strain is easily deformed during stretching, and exhibits excellent elastic recovery characteristics.

In general, it is already known that polyether-ester block copolymers having a polybutylene terephthalate polyester as a hard segment and a polyoxybutylene glycol polyether as a soft segment exhibit excellent elastic recovery properties. Many studies have been conducted on the method of producing an elastic yarn by melt spinning the polybutylene glycol terephthalate-based elastomer. However, the polybutylene terephthalate-based elastic yarn shows good recovery in the low elongation region in terms of elastic recovery rate, but does not reach rubber or polyurethane in the high elongation region.

In order to improve this disadvantage, Japanese Patent Laid-Open Nos. 59-45349, 59-45350, 58-91819, 58-91820, 58-98422, and 3,880,976, U.S. Pat. Increasing the initial modulus to lower the modulus, improving the nodule degree by mixing the crystal nucleating agent, heat-treating and stretching the polyether-ester block copolymer after melt spinning, stretching and heat-treating, and the like. Although proposed, the elastic yarn obtained by the above method has some schematic effects but still does not reach the physical properties of the spandex. Accordingly, it is an object of the present invention to provide a method for producing an elastic yarn that exhibits excellent stretch recovery even under high elongation as well as low elongation.

In order to achieve the above object, the present invention melt-spun polyether-ester block copolymer having a polybutylene terephthalate-based polyester as a hard segment and a polyoxybutylene glycol-based polyether as a soft segment, followed by extension heat treatment. And an elastic yarn having better elastic recovery characteristics by stretching and performing two-stage heat treatment of the relaxation heat treatment.

The present invention is described in more detail as follows.

The polyester portion constituting the hard segment of the polyether-ester block copolymer which is the basis of the elastic yarn has a polybutylene terephthalate made of a terephthalic acid component and a butylene glycol component as main components. However, a part of the acid component, generally 20 mol% or less, is substituted with a dicarboxylic acid component or an oxycarboxylic acid component other than the terephthalic acid component, and a part of the glycol component, and generally 20 mol% or less is other than the butylene glycol component. It is good to substitute with a deoxy component. In addition, the polyether portion constituting the soft segment includes polyoxybutylene glycol as a main component, but polyether in which 20 mol% or less of the repeating unit is substituted with a dioxy component other than butylene glycol component is preferable. However, if the average molecular weight of the polyether portion is less than 500, sufficient elastic properties are difficult to be obtained. If the average molecular weight of the polyether portion exceeds 5000, compatibility with the hard segment deteriorates, so that the molecular weight range is 500 to 5000, more preferably 1000 to 3000. Is effective. In addition, the blending ratio of the polyether portion to the polyester portion is preferably in the range of 0.25 to 4.0 times. If the blending ratio is less than 0.25, the elastic recovery property is lowered, and if it exceeds 4.0, the melting point decreases to be large, thereby obtaining sufficient thermal characteristics. it's difficult.

In preparing the polyether-ester block copolymer, a method commonly used in the art to which the present invention pertains is employed. In general, a method of heating and reacting terephthalic acid or dimethyl terephthalic acid, butylene glycol and polyoxybutylene glycol is used, but a method of synthesizing butylene terephthalate in advance and heating it and polyoxybutylene glycol is also effective. In the case of the above method, any catalyst may be used as necessary, and various stabilizers, ultraviolet absorbers, thickeners, colorants, and various other improving agents may be optionally used as necessary.

The polyether-ester block copolymers do not require any special means for melt spinning. That is, it is possible to carry out according to the melt spinning method of a general thermoplastic synthetic polymer, and unlike polyurethane elastic yarn, the fineness can be arbitrarily set like ordinary polyester fiber.

The yarns obtained by melt spinning the polyether-ester block copolymers exhibit excellent elastic properties and have a faster crystallization rate than conventional polyesters, but do not sufficiently crystallize the hardened segments. It is possible to improve the elastic properties by raising. In addition, since the orientation of the amorphous portion is also relaxed by heat, it becomes more random and has a better structure as an elastic yarn.

As the heat treatment method, it is possible to employ any method of suit heat treatment, extension heat treatment, and relaxation heat treatment, but in general, suit and extension heat treatment are good, and in particular, extension heat treatment is preferable.

The heat treatment temperature can be set within the range of the melting temperature of 30 ° C. or less near the glass transition temperature of the polybutylene terephthal-based polyester of the hard segment. However, when the melting temperature is approached, melt flow is generated and the elastic properties are not improved, and it is found that 20 ° C. to 120 ° C. is effective through repeated experiments. The heat treatment time can be arbitrarily set from an instant to several months depending on the heat treatment temperature and the target physical properties of the elastic yarn. The difference between suit heat treatment, extension heat treatment and relaxation heat treatment is described in detail in Japanese Patent Application Laid-Open No. 58-91819. The heat treatment is performed to increase crystallinity. There is no difference in crystallinity. However, structurally, there are significant differences between the three heat treatment methods. As a result of measuring the crystal size by X-ray, there was a significant difference between formal or extension heat treatment and relaxation heat treatment. That is, the size of the elastic yarn subjected to the relaxation heat treatment becomes larger than about 2 to 5 times larger than the crystal size of the elastic yarn subjected to the stretching or heat treatment. In the case of heat treatment under tension, it is thought that the harder the aggregation of hard segments, the larger the crystal size is.In the case of formal or stretch heat-treated elastic yarns, the crystallinity is about 2 to 5 times higher than that of loosely-treated elastic yarns. By having more, the more the crystals are dispersed. In particular, the extension heat treatment lowers the modulus more effectively than the suit heat treatment, which is considered to be because the non- government part is further alleviated. The heat treatment under elongation is preferably performed at an elongation rate of 20% or less.

As described above, the relaxation heat treatment is performed before stretching the yarn subjected to the extension heat treatment. As the elastic yarn, it is necessary to have high elongation due to low stress, that is, low elongation modulus is the most important requirement. The non-negative orientation is also relaxed by elongation heat treatment by elongation heat treatment, so that the non-negotiation becomes more random, but stress in the low extension region It is difficult to produce deformation under the initial extension due to its enlargement, so that the recovery of elongation in the low extension region is insufficient. Therefore, by performing the heat extension treatment and then performing the relaxation heat treatment at an appropriate temperature, the relaxation of the non-government is accelerated and the non-government becomes more random. Accordingly, the elongation modulus is lowered and the elongation is high with low stress. The low modulus area was up to 300% elongation, depending on treatment conditions. The heat treatment temperature is possible within the range of 50 ° C to 140 ° C and shows good results. If the temperature is less than 50 ℃ low mitigation effect of the non-government has a small effect of improving the modulus, if the temperature exceeds 140 ℃ melt pro will create a deterioration of the elastic properties.

The shrinkage rate under the relaxation shrinkage by heat treatment can be adjusted up to 50% under arbitrary conditions depending on the purpose of the elastic yarn to be obtained. Elongation and shrinkage in heat treatment are calculated by the following equation.

The yarn stretched and loosened by the above-described method is stretched. The stretching temperature is preferably 20 ° C. to 150 ° C., and the stretching ratio is preferably 2.0 to 4.0 times. If the draw ratio is less than 2.0 times, the crystals are difficult to undifferentiate due to stretching, and if the draw ratio is more than 4.0 times, the plastic deformation of the oriented non-orientation is large, so that it is not relaxed, and there is no characteristic as an elastic yarn.

The elastic yarn obtained by the method of the present invention increases the crystallinity by extension heat treatment, and the soft segment portion constituting the non-government by random heat treatment has a random structure, and by extension, the fine dispersion of the crystal of the hard segment portion progresses, resulting in low elongation. And excellent elongation recovery characteristics, which are easily deformed upon elongation due to low stress in the high elongation region. The elastic yarn according to the present invention having such a structure and physical properties exhibits good elongation recovery under low elongation and high elongation, and thus can be used in all fields in which polyurethane elastic yarn is used.

The following examples and comparative examples further illustrate the present invention, but do not limit the scope of the present invention. In addition, the physical properties of the elastic yarn prepared in Examples and Comparative Examples are measured as follows.

(Strength, Shinto)

A 5 cm long sample was measured at an rate of 500% per minute using an Instron tensile tester.

(Elastic recovery rate)

The length of the sample after removing the load after extending the load repeatedly to 100% and 300% elongation by applying the load corresponding to 100% and 300% elongation on 5cm of the sample with the same instrument as the strength measurement. ) Was calculated by the following equation.

Example 1

165 parts of dimethyl terephthalate, 105 parts of tetramethylene glycol, 320 parts of polyoxybutylene glycol with a number average molecular weight of 2000, 0.2 parts of pentaerythritol, 0.30 parts of titanium tetrabutoxide were placed in a reactor and subjected to transesterification at 170 ° C in the reactor. do. After 70% of the theoretical amount of methanol was distilled off, the reactor internal temperature was raised to 200 to 250 ° C., and the reaction was carried out for 60 minutes under low vacuum and 200 minutes under high vacuum. To the reaction mixture, 3.5 parts of Iganox 1010 (available from Ciba-Gaigi Co., Ltd.) and 0.21 parts of Tinuvin 327 (available from Ciba-Gaigi Co., Ltd.) were added to the reaction mixture, and the reaction was terminated after stirring for 20 minutes. The polymers produced had an inherent viscosity of 1.60 and a melting point of 190 ° C. (Intrinsic viscosity was measured at 25 ° C. using ortho chlorophenol) The polyma was melt spun at 240 ° C. to obtain an elastic yarn of 60 denia monofilament. Its strength was 1.2g / d, elongation was 450%, elastic recovery rate was 60% at 100% elongation and 30% at 300% elongation.

The elastic yarn was dissolved within 1 hour and subjected to heat treatment for 10 seconds at 10% elongation while passing through a dryer at 110 ° C., followed by a 15-second relaxation heat treatment for a shrinkage of 40% at 130 ° C. in a dry heat state at room temperature. The elastic yarn is prepared by stretching 2.0 times. The physical properties of the prepared elastic yarn are shown in Table 1.

[Examples 2-3]

As shown in Table 1, the elastic yarn was obtained in the same manner as in Example 1 except that the shrinkage ratio was 30% during the relaxation heat treatment or the stretching temperature was 60 ° C during stretching, and the physical properties are shown in Table 1.

[Comparative Examples 1 and 2]

The elastic yarns were obtained in the same manner as in Example 1 except that only the extension heat treatment or the extension heat treatment and the relaxation heat treatment were performed as described in Table 1, and the physical properties thereof were shown in Table 1 below.

Comparative Example 3

The undrawn yarn of 60 denier obtained in the same manner as in Example 1 was dissolved, stretched 2.0 times at room temperature, heat-treated for 10 seconds in a dry heat state at 110 ° C., and then continuously reduced to 15% at 130 ° C. in a dry heat state. The elastic yarn was obtained by performing a loose heat treatment for a second, and the conditions and the physical properties are shown in Table 1.

Comparative Example 4

In Comparative Example 3, the elastic yarn was obtained in the same manner as in Comparative Example 3 except that heat treatment was not performed during stretching, and the physical properties thereof were shown in Table 1 below.

TABLE 1

Claims (1)

Block-copolymerized polyether-esters having a polybutylene terephthalate polyester as a hard segment and a polyoxybutylene glycol polyether as a soft segment are melt spun and then subjected to a two-step heat treatment, i.e., elongation of 20% or less. After stretching heat treatment, and then relaxed heat treatment immediately to exhibit a shrinkage of 40% or less and stretched 20 to 4.0 times at 20 ℃ ~ 150 ℃.