JPS6346172B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing side-by-side composite fibers made of polyester polymers having different intrinsic viscosities. In particular, the object of the present invention is to provide a method for producing high-performance polyester composite crimped yarn at high speed. Conventionally, the mainstream method for manufacturing crimped yarn has been the false twisting process, and with the recent appearance of friction false twisting units, this method has become faster than the spindle type false twisting that was previously available. However, it is still only about 1000 m/mm at most, and a significant improvement in productivity cannot be expected even with direct spinning processing. To deal with this, various methods have been proposed in which the drawn yarn is preheated and then bulked with heated air (for example,
Publication No. 53-35175, US Patent No. 3729831,
(U.S. Pat. No. 3,852,857). Although these methods are superior in terms of speeding up, they are inferior in bulk as processed yarns used for clothing, and because the processing method causes excessive heat shrinkage of the fibers, they cause problems such as dye spots and mechanical problems. It is inferior in physical properties (high elongation, easy to stretch). For this reason, this technology uses single yarn denier,
It is used to manufacture carpet tufted yarn with a large total denier. On the other hand, a method of heat setting using an air forced nozzle after false twisting (Japanese Unexamined Patent Publications No. 119348/1982, No. 68433/1983)
Although it has also been proposed (Japanese Patent Publication No. 2003-12101), it is difficult to process at high speeds and is not suitable for direct spinning processing. In contrast to these methods, a method has been proposed in which polyester composite fibers having a difference in intrinsic viscosity are spun at high speed to produce crimped and bulky processed yarns (Japanese Patent Publication No. 1973).
-13848). However, with this method, the difference in intrinsic viscosity is small and the intrinsic viscosity itself is too high, making it impossible to obtain processed yarn with bulk and texture suitable for clothing applications. Furthermore, a method has also been proposed in which composite spinning of different types of polymers is carried out, followed by stretching heat treatment and heated air processing (U.S. Pat. No. 4,115,989, U.S. Pat.
(Specification No. 4118534, Japanese Utility Model Publication No. 46-9535, Japanese Patent Publication No. 45-37576, Japanese Patent Application Laid-open No. 42441-1982).
However, although these methods are suitable for high-speed processing, the bulk and mechanical properties of crimped yarns are inferior, and they are still unsuitable for clothing applications. Furthermore, a method has been proposed in which composite spinning of different types of different polymers is carried out, and processing is carried out using a heated fluid after drawing heat treatment (Japanese Patent Application Laid-open No. 169830/1983). This proposed product has good crimp bulk and mechanical properties, and can be used for clothing, but production efficiency cannot be improved because the spinning speed is extremely low and it requires stretching heat treatment. The present invention aims to solve the drawbacks of these conventional methods and obtain a crimped yarn with good crimped bulk and mechanical properties by ultra-high-speed spinning. This was developed based on a completely new idea based on the results of research on physical properties. That is, in producing a side-by-side type composite fiber made of polyester having an intrinsic viscosity difference Δ[η]f, the present invention uses a polyester constituting a polyester component having a low intrinsic viscosity as a polyester having a ~10 mol% isophthalic acid component,
A polyester in which 3 to 10 mol% of a diethylene glycol component or a triethylene glycol component is copolymerized is used, and the intrinsic viscosity [η] f of the polyester component is 0.34 to 0.50, and the difference in intrinsic viscosity between both polyester components △ [η] f is 0.20 to 0.30,
This is a method for producing polyester composite fibers, which is characterized by spinning at a spinning speed of 4000 to 5500 m/min. As for the polyester in the present invention, polyethylene terephthalate is mainly used for the polyester component with a higher intrinsic viscosity, and polyethylene terephthalate is mainly used as the polyester component with a lower intrinsic viscosity.
A copolymerized polyester in which ~10 mol% of an isophthalic acid component, a diethylene glycol component, or a triethylene glycol component is copolymerized is used. In this way, fibers in which a polyester component mainly composed of polyethylene terephthalate and a copolymerized polyester component having an intrinsic viscosity lower than that of the polyester component are composited side-by-side exhibit a higher degree of crimp. be able to. Here, if the copolymerization amount is less than 3 mol%,
It is not possible to expect a higher degree of crimping,
On the other hand, if the amount of copolymerization exceeds 10 mol%, it becomes difficult to spin a polymer with a low intrinsic viscosity due to a decrease in viscosity, a decrease in melting point, etc. The basic idea of the present invention is to utilize the fact that the physical properties of the spun yarn vary significantly depending on the intrinsic viscosity [η]f of the spun yarn in ultrahigh-speed spinning. That is,
According to our basic research, in the melt spinning of general polyethylene terephthalate, there is a relationship between spinning speed and heat shrinkage rate as shown in the figure. In the figure, the behavior of a yarn with a high intrinsic viscosity [η]f is shown by a solid line, and the behavior of a yarn with a low intrinsic viscosity [η]f is shown by a dotted line. In the low spinning speed range of 2500 m/mm or less (area in the figure), molecular chain orientation increases with increasing spinning speed for both high [η] f and low [η] f yarns.
The higher [η]f the yarn, the greater the heat shrinkage rate. Since these yarns have low strength and high elongation, they cannot be used by themselves, so they are subsequently subjected to drawing heat treatment. The density of the yarn obtained at this time is lower as the [η] f yarn is higher, and therefore the heat shrinkage rate is higher. Side-by-side type composite fibers based on polyester with different intrinsic viscosity utilize this difference in shrinkage properties between high [η]f and low [η]f yarns, and most of the fibers proposed in the past are belongs to this area. One example is the technique described in Japanese Patent Application Laid-Open No. 169830/1983. However, when the spinning speed was further increased to 2,800 to 3,200 m/
In the area of min, that is, the area of the figure, surprisingly, the spun yarn has high [η] f, low [η] f, and
There is no significant difference in the physical properties of the drawn and heat-set yarn. That is, in this spinning speed range, it is extremely difficult to obtain high bulkiness with composite fibers that utilize the difference in intrinsic viscosity. For this reason, it is presumed that the preferred spinning speed in the claims of the above-mentioned Japanese Patent Application Laid-Open No. 169830/1983 is 2000 m/min at most. However, what is even more surprising is that as the spinning speed is further increased (area of the figure), the density of the spun yarn increases and the shrinkage rate of the spun yarn decreases as the spinning speed increases. From this region, differences in physical properties begin to appear again between high [η]f and low [η]f spun yarns. However, in this region, the higher the [η]f yarn, the higher the density and therefore the lower the shrinkage rate. This is the opposite phenomenon to the area shown in the figure. These spun yarns have low strength and high elongation, so drawing heat setting is required, but when heat setting, both high [η] f and low [η] f yarns exhibit extremely similar high densities. , the difference in shrinkage properties disappears. If the spun yarn of the side-by-side composite fiber with intrinsic viscosity difference is subjected to relaxation heat treatment without drawing heat setting in this spinning speed range, crimp occurs. However, once a material has been heat treated under tension, even if it is subsequently subjected to relaxation heat treatment, only a very small degree of crimp structure will occur. Utilizing this phenomenon, it is possible to develop a crimp structure by directly applying relaxation heat treatment without stretching heat setting after spinning, but the resulting yarn has extremely high elongation and low strength. cannot withstand use. Next, at higher speeds of about 4,000 to 5,500 m/min (region in the figure), spun yarn alone has high density, low shrinkage, and high strength, making it possible to obtain a product that can withstand use. Fortunately, in this region, there is a large difference in the physical properties of the two spun yarns due to the difference in intrinsic viscosity. Based on this knowledge, an extremely good crimp structure was obtained when the spun yarn of the side-by-side composite fiber with inherent viscosity was subjected to relaxation heat treatment. However, no matter how much relaxation heat treatment was applied to the material that had once been subjected to stretching heat setting or tension heat treatment, no crimp structure was developed. This is the same phenomenon as in the area of , and the reason is that if the composite fiber is subjected to tension heat treatment that does not form a crimp structure, crystallization will proceed in that state and the side-by-side structural difference will disappear. This is thought to be due to the fact that
Note that even if a crimp structure is first developed and then heat treatment is performed at a higher temperature, the crimp structure will not disappear, crystallization will proceed further, and a morphologically stable structure will be obtained. The main feature of the present invention is to utilize the above knowledge to spin side-by-side composite fibers with intrinsic viscosity difference at a spinning speed of 4,000 m/min to 5,500 m/min, and heat-treat the fibers in a relaxed state. It is. As the spinning speed is further increased (in the region of the figure), the density increases even for low [η] f yarns, and once again there is no difference in physical properties between high [η] f and low [η] f yarns. Put it away. From this, the spinning speed of the present invention is 4000 to 5500.
It is preferred that the spun yarn in the range of m/min is subjected to direct relaxation heat treatment. The next important thing is that in both side-by-side components, the intrinsic viscosity [η]f on the low [η]f side is
It should be within the range of 0.34 to 0.50. If [η]f is smaller than 0.34, thread breakage during melt spinning and staining of the spinneret surface will occur, making stable spinning impossible. On the other hand, if it exceeds 0.50, the spinnability will improve, but the latent crimp performance of the spun yarn will deteriorate even if the intrinsic viscosity difference Δ[η]f and the spinning speed are within the range of the present invention. The reason for this is that crystallization during the spinning stage is promoted as [η] f increases, and the intrinsic viscosity [η] f on the high [η] f side is reduced to the intrinsic viscosity [η] f on the low [η] f side. Even if the value is increased to match the increase in f, if [η]f exceeds 0.70,
The two reasons for determining the upper limit of low [η]f are that crystallization begins to show a tendency to saturate and the physical property difference between the two components decreases. The next important thing is that the difference in intrinsic viscosity between both components △
[η] f is 0.20 to 0.30. This△
[η] When f is smaller than 0.20, it becomes difficult to obtain sufficient crimp performance. If it is larger than 0.30, bending of the polymer on the spinneret surface during spinning becomes large, resulting in extremely poor spinnability. The polyester composite fiber thus obtained is
Good crimping can be achieved by subjecting the material to relaxation heat treatment as it is, but without further stretching, pre-relaxation heat treatment is performed at a temperature of 80°C to 120°C under a tension of 0.03 g/dl or less, and then at 160°C.
By performing a relaxation heat treatment at a temperature of ~220°C, a composite crimped yarn of even better quality can be obtained. Here, the reason for performing the relaxation preheat treatment is that, as explained earlier in relation to the spinning speed and the physical properties of the spun yarn, when directly subjected to tension high temperature heat treatment, the side
This is because both the buy side and side components crystallize and no longer have a crimp structure.
It is necessary to perform a relaxation preheat treatment in advance to develop a crimp structure. Here, the tension may be 0.03 g/dl or less. If the size is larger than this, it becomes difficult to effectively relax the crimp structure, resulting in an inferior crimp structure. In addition, as for the temperature, in order to express the potential shrinkage performance between side-by-side components,
Must be higher than the glass transition temperature, 80
~120°C is suitable. Note that even if the temperature is higher than 120°C, if the temperature is sufficiently relaxed, a crimp structure will be formed, but if the temperature is too high, both side-by-side components will shrink, and the resulting crimp performance will deteriorate. After the pre-relaxation heat treatment is performed in this manner, the material is further subjected to a high temperature relaxation heat treatment under low tension. This is because crystallization does not progress sufficiently with relaxation preheat treatment alone, and the crimp structure tends to collapse during subsequent processing steps (dying, fabric tensioning, final setting). That is, high-temperature heat treatment is desirable in order to promote crystallization and stabilize the structure.
The temperature used is 160°C to 220°C, where crystallization progresses; if it is lower than this temperature, the structure stabilizing effect in the above-mentioned post-process will be reduced, and if it is too high, shrinkage will occur and the crimp structure will deteriorate. A phenomenon of shrinkage is observed. The reason why the treatment is performed in a relaxed state is that if the tension is increased and the high temperature heat treatment is performed, the crimp structure will become stale. On the other hand, even if the yarn after being spun is subsequently subjected to relaxation heat treatment at 160 to 220° C. using a heated fluid forcing nozzle, a good composite crimped yarn can be obtained. Relaxation heat treatment temperature with heated fluid forced nozzle is 160℃
to 220°C is suitable. If it is below 160°C, it will not be able to withstand the temperature at which it is processed after being made into a woven or knitted fabric (tension set at about 180°C), and the crimping will become flat.
Also, when the temperature is higher than 220℃, the high [η]f of the spun yarn,
There is a phenomenon that the low [η] f side also shrinks significantly and the expression of crimp decreases. From this, 160℃
It is preferable to carry out the relaxation heat treatment in the above manner, and to proceed with crystallization at the same time as the appearance of crimp. Many side-by-side composite fibers made of homopolyester and copolyester have been proposed, but all of them use copolyester on the high [η] f side. This is largely different from the present invention. To explain this point, most of the conventional technologies are low-speed spinning systems of 2000 m/min or less, and in this speed range, the high [η] f side must be the high shrinkage side, so shrinkage is improved. In order to achieve this, a copolymer component was used on the high [η] f side. However,
Since the present invention is a high-speed spinning system, it has a low [η]
The shrinkage must be higher on the f side, and for this reason it is better to use a copolymer component on the low [η] f side. In the present invention, dimethyl isophthalate-5 is a crystallization promoter that lowers the shrinkage rate toward the high [η]f side.
Addition of sodium sulfonate or the like also improves crimp performance. Furthermore, the relaxation heat treatment performed to develop crimp in the composite fiber obtained by the present invention may be performed directly in conjunction with melt spinning, or may be performed in a separate step. That is, the material may be melt-spun and once wound up and then subjected to a relaxation heat treatment, or further may be processed after knitting and weaving. The present invention will be explained below with reference to Examples. Tc, which represents crimp performance in the present invention, was measured as follows. Tc=l ₀ −l ₁ /l ₀ ×100% l ₀ is in boiling water with a load of 2 mg per denier.
After processing for 20 minutes, take it out and dry under this load for a day and night below 40℃, then apply a load of 200 mg per denier and measure the _length after ₁ minute. This is the length after 1 minute with a load of 2 mg applied to each tube. In addition, the intrinsic viscosity [η] f is the intrinsic viscosity measured with a free-hole (free-falling) filament, and the free-hole (free-falling) filament is
In side-by-side composite spinning, the measurement is performed using a free-hole filament in which one side of the polymer is stopped and only the other polymer is spun. In this case, [η]f is determined by the following equation. [η]f = ^lin _c → ₀ In(ηrel)/c (ηrel) is the viscosity of a dilute solution of polyester using a mixture of 60% phenol and 40% carbon tetrachloride as the solvent measured at the same temperature and in the same units. is the ratio to the viscosity of the mixture, where C is the number of grams of polyester in the 100 c.c. mixture. Example: Two types of polyethylene terephthalate with different intrinsic viscosities were melt-spun by a conventional method and spun at 180°C.
150 denier /
A composite crimped yarn of 48 filaments was obtained. At that time, the intrinsic viscosity [η]f and spinning speed of both components of the spun yarn were varied as shown in Table 1. The fabric evaluation is 2-2 twill with a basis weight of approximately 150g/
I went to the one that was dyed and finished in a size of ^m2 . Texture, sink marks, and spots are determined by touch and with the naked eye.
◯ indicates good, △ indicates slightly poor, and × indicates poor.

[Table] Experiments Nos. 18 to 20, which are within the scope of the present invention, have higher crimping of the resulting composite fibers than Experiments Nos. 1 to 11 and Experiments Nos. 14 to 17, which are outside the scope of the present invention. A uniform woven fabric with good properties and a good feel without "sink" or "spots" can be obtained.

[Brief explanation of the drawing]

The figure is a graph showing the relationship between spinning speed and heat shrinkage rate of spun yarn for polyethylene terephthalate. The solid line is high [η] f yarn, the dotted line is low [η] f
It shows the behavior of the thread.

Claims (1)

[Claims] 1. When producing a side-by-side composite fiber made of polyester having an intrinsic viscosity difference Δ[η]f, as a polyester constituting a polyester component with a low intrinsic viscosity, 3
Using a polyester in which 3 to 10 mol% of an isophthalic acid component, a diethylene glycol component, or a triethylene glycol component is copolymerized in an amount of ~10 mol%, and the intrinsic viscosity of the polyester component [η]
f is 0.34 to 0.50, intrinsic viscosity difference △ [η] f of both polyester components is 0.20 to 0.30, and 4000 to 5500 m/
A method for producing a polyester composite fiber, which is characterized by spinning at a spinning speed of 1 minute.