JPS6360127B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an elastic yarn made of block copolymerized polyether polyester (hereinafter sometimes referred to as block copolymerized polyether polyester) having extremely excellent elastic properties. More specifically, it relates to a method for producing elastic yarn, which comprises melt-spinning a block copolymerized polyether polyester having polybutylene terephthalate-based polyester as a hard segment and polyoxybutylene glycol-based polyether as a soft segment, followed by heat treatment. It is something.

It has been known that block copolymerized polyether polyester, which has polybutylene terephthalate polyester as a hard segment and polyoxybutylene glycol polyether as a soft segment, exhibits elasticity. It has also been proposed to spin it into elastic yarn.

However, polyethylene terephthalate-based elastic threads are not satisfactory in terms of their melt spinnability and elastic properties, and have not yet been put into practical use. The biggest problem with its melt spinnability is that the single filaments and multifilaments fuse together during the process from spinning to winding, and winding may even become impossible. Possible measures to solve this problem include increasing the weight ratio of the hard segment and lengthening the cooling zone after melt extrusion. However, the former method not only fails to sufficiently prevent fusion, but also deteriorates the elastic properties of the resulting elastic yarn. In addition, in the latter method, as the cooling region becomes longer, the air resistance increases, so the tension applied to the spun yarn increases, causing yarn breakage, poor winding performance, and even worse. It becomes impossible to roll it up.

In terms of elastic properties, block copolymerized polyether polyester has crystallized hard segment parts that are finely and widely distributed in the amorphous soft segment as small crystals, and the hard segment part covers the amorphous part of the soft segment. They serve as intertwining points for the rubber-like network structure that holds them together. In reality, it is common to think of the segment as being divided into three parts: a crystallized hard segment, a soft segment that becomes oriented and crystallized when stress occurs, and a completely amorphous soft segment. The generation of elastic recovery force is greatly influenced by the strength of the binding effect of the hard segments when stress is generated, and it is necessary that the hard segments have high crystallinity and that the hard segment crystals are efficiently distributed. It is not a good idea to increase the polymerization ratio of hard segments for threads, as polyethylene terephthalate does not have sufficient crystallinity, and if it is used as a hard segment, the binding effect will be weak.
It is necessary to combine post-treatments such as stretching and heat treatment. However, in the case of polybutylene terephthalate elastic yarns, stretching treatment is difficult, and heat treatment alone is not effective because crystallization is insufficient in terms of internal structure.

As described above, polyethylene terephthalate-based elastic yarns have poor melt spinning properties and insufficient elastic properties, so they have not been put to practical use. The present inventor has arrived at the present invention as a result of intensive studies aimed at providing an elastic yarn with excellent elastic properties inexpensively and easily using a melt spinning method.

That is, the present invention provides an elastic yarn characterized by melt-spinning a block copolymerized polyether/polyester having polybutylene terephthalate polyester as a hard segment and polyoxybutylene glycol polyether as a soft segment, and then heat-treating the yarn. This relates to the manufacturing method.

The polyester portion constituting the hard segment of the block copolymerized polyether polyester that is the base of the elastic yarn of the present invention is mainly polybutylene terephthalate consisting of a terephthalic acid component and a butylene glycol component. However, even if a part of this acid component, usually 30 mol% or less, is replaced with a dicarboxylic acid component or an oxycarboxylic acid component other than the terephthalic acid component, and/or a part of the glycol component, usually 30 mol% or less, is replaced by a butylene glycol component. It may also be a polyester substituted with a dioxy component other than the above. The polyether moiety constituting the soft segment is mainly polyoxybutylene glycol, but may be a polyether in which 30% or less of its repeating units are replaced with a dioxy component other than the butylene glycol component.

The average molecular weight of the polyether moiety is preferably in the range of 500 to 5000, because if it is too small, it will be difficult to obtain sufficient elastic properties, and if it is too large, the compatibility with the hard segment will deteriorate. A range of 3000 is particularly preferred. In addition, if the ratio of the polyether part to the polyester part is too small, it will be difficult to obtain sufficient elastic properties, and if it is too large, the melting point will decrease significantly and it will be difficult to obtain sufficient thermal properties. The range of 0.25 to 4.0 times is preferable, and the range of 0.4 to 2.5 times is particularly preferable.

Any method can be used to produce the block copolymerized polyether polyester. Usually, a method is employed in which terephthalic acid or dimethyl terephthalate is heated and reacted with butylene glycol and polyoxybutylene glycol, or butylene terephthalate is synthesized in advance and this is heated and reacted with polyoxybutylene glycol. At this time, any catalyst can be used as required, and various stabilizers, ultraviolet absorbers, thickening and branching agents, matting agents,
Coloring agents and other various improving agents can also be used as desired.

The above-mentioned block copolymerized polyether polyester is easily solidified during melt-spinning, so that the filaments are hardly fused together and can be melt-spun extremely easily. Note that this melt spinning does not require any special means and can be carried out in accordance with the melt spinning method for general thermoplastic synthetic polymers.

That is, unlike polyurethane elastic yarns, the threads and single yarn denier can be set arbitrarily, similar to ordinary polyester fibers.

The yarn obtained by melt spinning the above block copolymerized polyether polyester exhibits elasticity, but
As with normal polyester, the crystallinity of the hard segment is not very high. On the other hand, polybutylene terephthalate has a faster crystallization rate and higher crystallinity than polyethylene terephthalate. Therefore, in the case of polybutylene terephthalate elastic yarns, the hard segment parts that have not yet been sufficiently crystallized are heat treated to increase the degree of crystallinity and improve the binding effect of the crystals, thereby further improving the instantaneous elongation recovery rate and elongation elasticity. It is possible to improve elastic properties such as elasticity and long-term elongation recovery rate.

The heat treatment temperature can range from 20°C or higher, which is around the glass transition temperature of the hard segment polybutylene terephthalic polyester, to 160°C. When the temperature exceeds 160°C, melt flow begins to occur and the effect of improving elastic properties disappears. Empirically, it is preferable to use a temperature of 20 to 100°C, and it is characterized in that it can be heat treated at a lower temperature than polyethylene terephthalic elastic yarn.

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 yarn.

The timing of the heat treatment is arbitrary, but it is necessary to perform the heat treatment without stretching. If heat treatment is performed after drawing, the stress under low elongation will increase, making it impossible to obtain a yarn exhibiting the desired load-elongation behavior.

This heat treatment may be carried out under any of the following conditions: relaxed, constant length, or elongated; however, uniform heat treatment can be achieved when the heat treatment is performed under constant length or elongation, and for the following reasons. preferable. That is, heat treatment is performed to improve crystallinity, and if the temperature and time conditions are the same, the degree of crystallinity will not change regardless of whether the heat treatment is constant length heat treatment, relaxation heat treatment, or elongation heat treatment. However, there is a large structural difference between the three, and the crystal size of the hard segment determined by X-rays is different between fixed length heat treatment, elongation heat treatment, and relaxation heat treatment, and the elastic yarns subjected to the latter treatment have different crystal sizes. The crystal size becomes extremely large, about 2 to 5 times that of the former heat-treated one. This phenomenon is thought to be due to the fact that in the case of heat treatment without tension, hard segments tend to aggregate due to the heat treatment and the resulting relaxation, resulting in an increase in crystal size. Therefore, even if the degree of crystallinity is the same, elastic yarns subjected to constant length or elongation heat treatment have about 2 to 5 times as many small crystals as those subjected to relaxation heat treatment, and the crystals are more dispersed. This means that it has been done. This indicates that constant length or elongation heat-treated products are superior in terms of the binding effect of hard segment crystals to improve elastic properties. In fact, excellent results have been obtained regarding instantaneous elongation recovery rate, elongation modulus, and creep property.

The heat treatment under relaxation contraction is preferably performed at a shrinkage rate of 30% or less, and the heat treatment under elongation is preferably performed at an elongation rate of 20% or less.

The load curve of the elastic yarn obtained in this way has a shape as shown in FIG.
This curve was obtained by subjecting the spun yarn to constant length heat treatment, and three major characteristics were discovered by subjecting the constant length heat treatment to the spun yarn. The first is that the elongation at break increases, the second is that even if the elongation increases, the stress at break hardly changes, and the elongation curve becomes a curve parallel to the high elongation side. The initial modulus becomes low. The third, low initial modulus, is the most important factor for elastic yarns. In other words, as an elastic yarn, it is necessary to have high elongation with low stress, and from a structural standpoint, the orientation of the amorphous portion that seems to occur slightly during spinning is also released by heat treatment, making it non-crystalline. The crystal parts are more random, and this structure is considered to be preferable due to improved elasticity.

The elastic yarn obtained by the method of the present invention having such structure and physical properties exhibits good elongation recovery under low elongation of 100% or less, and overcomes the shortcomings of polyurethane elastic yarns such as small deformation due to excessive elongation. This solves the problem of poor workability in the stretch area.
Fields where polyurethane elastic yarn has traditionally been used, such as jackets, which are small deformation stretch fields;
It can be used for slacks, suits, lingerie, socks, etc. to improve workability.

In addition, with this method, it is possible to some extent to control the rising part of the stretching curve b shown in the figure where the elongation is 50 to 150%, and in the region where the elongation is low, the elongation is carried out with low stress and gradually Since it has a stress-elongation pattern in which the higher the stress, the more difficult it is to elongate, it can also be used as a material for shock-absorbing belts by setting appropriate heat treatment conditions.

The present invention will be explained in further detail by giving examples below.
In addition, parts in Examples are weights, and the strength, elongation, and elastic properties of the product yarns were measured by the methods shown below.

1 Strength, elongation A sample with a length of 5 cm was elongated at a speed of 1000% per minute,
Strength is the strength per denier (g/de) at break,
Elongation is expressed as elongation at break (%).

2 Elongation recovery (1) Instantaneous elongation recovery rate Apply a load corresponding to 50% or 100% elongation to a 10 cm sample, quickly elongate it by 50% or 100%,
After 5 seconds, remove the load, quickly read the length of the sample in cm, and calculate it using the following formula.

Instantaneous elongation recovery rate = 10 - (-10) / 10 x 100 (%) (2) Elongation modulus JIS L1073 (1977) Synthetic fiber test method Elongation elastic modulus B method 10%, 50 % or elongation elastic modulus at 100% elongation.

(3) Long-term elongation recovery rate A load equivalent to 100% elongation was applied to a 10 cm long sample and left for 4 hours (the sample length at this time
cm), then remove the load and measure the sample length 'cm after leaving it for 4 hours, and calculate it using the following formula.

Long-term elongation recovery rate = -'/10 x 100 (%) 3 Creep A load equivalent to 100% elongation is applied to a 10 cm long sample and left for 4 hours.
Measure cm and calculate using the following formula.

Creep = (-10) -10/10 x 100 (%) Example 1 230 parts of dimethyl terephthalate, 159 parts of tetramethylene glycol, 105 parts of polyoxybutylene glycol with a number average molecular weight of 2000, 0.11 part of pentaerythritol, titanium tetrabutoxide Pour 0.26 parts into a reaction vessel, perform a transesterification reaction at an internal temperature of 170°C, and after distilling off 65% of the theoretical amount of methanol, raise the internal temperature to 200-245°C and under weak vacuum for 60 minutes. ,
The reaction was then carried out under high vacuum for 200 minutes. Here, Irganox 1010 (manufactured by Ciba Geigy) is used as a stabilizer.
3.5 parts and 0.21 parts of Tinuvin 327 (manufactured by Ciba Geigy) were added, and the reaction was terminated after stirring for 20 minutes.

The polymer thus obtained has a soft component of 30% by weight based on the total polymer weight, and a reduced specific viscosity of
1.811, and the melting point was 210°C. This polymer is 260
A 135 denier elastic yarn was obtained by melt spinning at ℃.
The strength is 0.44g/de, the elongation is 250%, the instantaneous elongation recovery rate is 82% at 50% elongation, and 73% at 100% elongation, and the elongation elastic modulus is 100% at 10% elongation, and 100% at 50% elongation.
74%, 52% at 100% extension, long-term extension recovery rate is 65
%, and creep was 30%.

Three days after spinning the elastic yarn, it was heat-treated in a dry heat oven at 160° C. for 10 seconds at a constant length. The strength of the elastic yarn thus obtained was 0.46 g/de, the elongation was 280%,
Instantaneous elongation recovery rate is 88% at 50% elongation and 88% at 100% elongation
76%, and the elongation modulus is 100% at 10% elongation, 50
Excellent elasticity was obtained with slight heat treatment, with 81% at % elongation, 60% at 100% elongation, long-term elongation recovery rate of 58%, and creep of 20%. The load curve of the obtained elastic yarn is as shown in Figure b, and the load curve of the yarn without heat treatment is as shown in Figure A.

Example 2 167 parts of dimethyl terephthalate, 105 parts of tetramethylene glycol, 325 parts of polyoxybutylene glycol with a number average molecular weight of 2000, 0.5 parts of pentaerthritol, and 0.35 parts of titanium tetrabutoxide were placed in a reaction vessel, and the mixture was heated at an internal temperature of 170°C. After carrying out the transesterification reaction and distilling off 65% of the theoretical amount of methanol, the internal temperature was raised to 200°C to 245°C and heated to 60°C under weak vacuum.
minutes, then reacted under high vacuum for 200 minutes. Here the stabilizer Irganox 1010 (manufactured by Ciba Geigy)
5 parts and 0.3 parts of Tinuvin 327 (manufactured by Ciba Geigy) were added, and the reaction was terminated after stirring for 20 minutes.

The obtained polymer has a soft component of 65% by weight based on the total polymer, a reduced specific viscosity of 2.19, and a melting point of
It was 191℃. This polymer was melt spun at 260°C to obtain a 135 denier elastic yarn. Its strength is
0.92g/de, elongation 400%, instantaneous elongation recovery rate 50%
95% at elongation, 88% at 100% elongation, elongation modulus is 10
100% at % expansion, 80% at 50% expansion, 75 at 100% expansion
%, long-term extension recovery rate is 140%, creep is 60%
It was hot.

One hour after spinning such elastic yarn, it was heated to 165℃.
Dry heat treatment was carried out at a fixed length for 20 seconds. At this time, the strength of the elastic thread is 0.92 g/de, elongation is 450%, instantaneous elongation recovery rate is 97% at 50% elongation, 91% at 100% elongation, elongation elastic modulus is 100% at 10% elongation, 50 % elongation 86%,
At 100% elongation, the elastic recovery rate was 79%, the long-term elastic recovery rate was 120%, and the creep was 50%.

This elastic yarn was excellent in melt spinnability and elasticity, and had excellent workability.

[Brief explanation of drawings]

The figures show the drawing curves of elastic yarns, where a shows the drawing curves of unheated yarns and b shows the drawing curves of heat-treated yarns according to the method of the present invention.

Claims (1)

[Scope of Claims] 1. Elasticity characterized by melt-spinning block copolymerized polyether/polyester having polybutylene terephthalate polyester as a hard segment and polyoxybutylene glycol polyether as a soft segment, and then heat-treating it. How to make yarn. 2. The method for producing elastic yarn according to claim 1, wherein the heat treatment temperature is 20 to 160°C. 3. The method for producing elastic yarn according to claim 1 or 2, wherein the heat treatment is performed under a shrinkage of 30% or less. 4. The method for producing elastic yarn according to claim 1 or 2, wherein the heat treatment is performed under elongation of 20% or less. 5 Claim 1 in which heat treatment is performed under a fixed length
2. A method for producing elastic yarn according to item 1 or 2.