JPS6260484B2 - - Google Patents

Description

[Detailed description of the invention]

B. Technical Field of the Invention The present invention relates to a polyamide-based twisted yarn and a method for producing the same, and more particularly to a polyamide-based twisted yarn that has high shrinkage ability and excellent heat resistance, and a rational method for producing the same. . B. Conventional technology and its problems Polyamide-based temporarily twisted yarn has been known for a long time.
It has superior stretchability compared to temporarily twisted yarns made of other polymers such as polyester, and is widely used as raw yarn for stretch woven and knitted fabrics. However, as the sophistication of sports clothing is rapidly progressing, the requirements for stretch materials are also becoming more sophisticated, and it is becoming difficult to meet these requirements with the polyamide temporary twist yarns that have been used up until now. Spandex is mixed and knitted for clothing that requires a particularly high degree of stretch.
Although it is a mixed weave, it has the problem of increasing costs. C. Object of the present invention The present invention provides a twisted yarn made of polyamide continuous filament yarn that can realize a woven or knitted fabric with excellent stretchability, and a rational method for producing the same. D. Structure of the present invention The present invention consists of the following structure. That is, the polyamide pre-twisted yarn of the present invention has a maximum dry heat shrinkage stress F of the pre-twisted yarn made of polyamide continuous filament yarn.
(grams) and the heat treatment temperature T (℃) at which the dry heat shrinkage stress reaches its maximum value is 0.20D≧F≧0.08D Tm≧T≧Tm−25, and the shrinkage recovery rate CR (%) is 15%. This is a polyamide-based temporarily twisted yarn characterized by the above characteristics. In addition, the method for producing the polyamide filament yarn of the present invention involves stretching the polyamide continuous filament yarn, feeding it to a temporary twisting machine, and subjecting it to stretching, heat setting, and unraveling, or In a method for producing a temporary twisted yarn, which is supplied to a temporary twisting machine and stretched, heat-set, and unrolled at the same time, the birefringence △ of the polyamide continuous filament yarn fed to the temporary twisting machine is
n, applied tension t (grams/denier) and heat set temperature H (℃) satisfy the following relationships: △n≧35×10 ^-3 0.8≧t≧0.4 Hm−10≧H≧Hm−25 This is a method for producing a polyamide-based temporarily twisted yarn. However, in the above, D is the fineness (denier) of the temporarily twisted yarn, Tm is the melting temperature (°C), and Hm is the melting point (°C) of the polyamide continuous filament yarn after drawing. The present invention will be explained in further detail. The dry heat shrinkage stress according to the present invention is measured as follows. Using a thermal stress measuring machine model KE-1 manufactured by Kanebo Engineering Co., Ltd., sample length: 20 cm, temperature increase index: 120 seconds/300°C, initial load: 0.1 g/denier, number of measurements: 5 times. FIG. 1 shows an example of the measurement. The maximum value F (grams) of dry heat shrinkage stress is the maximum value F _A (grams) of shrinkage stress in Figure 1.
The value is obtained by reading the value, subtracting the initial tension F _O (grams) from that value, and making it 1/2. F = 1/2 (F _A - F _O ) The heat treatment temperature T (°C) is the temperature at which the shrinkage stress reaches the maximum value F _A , and the melting temperature Tm (°C) is the temperature at which the shrinkage stress becomes zero. (Figure 1). The shrinkage recovery rate CR ₂ (%) is determined as follows. The measurement procedure and calculation formula are shown below. Measurement procedure (1) Directly from bread or corn (cheese), use a skein winding machine with a circumference of approximately 80 cm ⁽¹⁾ to make a 10-turn skein by applying a uniform load of less than 1/10 g of the indicated denier. (2) Remove the skein from the skein winding machine, gently apply a load ⁽²⁾ of 1/10 g per indicated denier, remove skein disturbances and tangles due to shrinkage, and then apply an initial load ⁽³⁾ of 2 mg per indicated denier. Gently remove the load applied earlier. (3) Next, hold the skein at 98±1℃ with the initial load hanging down.
Soak in hot water for 20 minutes. (4) Remove the soaked skein, remove the initial load, drain the water with absorbent paper, and leave the skein undisturbed for about 12 hours or more to achieve moisture equilibrium. (5) Hang one end of the skein after it has been left on a hook, apply an initial load of 2 mg per indicated denier ⁽³⁾ and a load of 1/10 g per indicated denier ⁽²⁾ to the other end, and quickly tighten the skein to 20 ± 2 to avoid shock. °C underwater
⁽⁴⁾ , fix the hook and leave it for 2 minutes. (6) Measure the inside length of the left skein. (1mm
(7) After measuring the length, gently remove the load under water and leave it under the initial load for 2 minutes. (8) Measure the inside length of the left skein. (1mm
(Read down to the unit) (9) Calculate CR ₂ (%) from the inside length of the skein found above using formula 3.2. (Up to 1 decimal place) Note: (1) If you do not have a skein winding machine with a workpiece circumference of approximately 80cm, you may use a measuring machine with a workpiece circumference of 100m or 1125m. (2) The load is the weight in water, which is 1/10g of the indicated denier x the total number of threads in the skein (20). (3) The load is the weight in water, which is 2/1000g of the indicated denier x the total number of threads in the skein (20). (4) Mix 2-3 drops of surfactant into the water to improve wetting of the thread surface. Calculation formula CR (%) = l-l ₁ / l x 100 where l: Initial load and inner length of the skein when the load is applied (mm) l ₁ : Initial load after removing the load Length inside the skein (mm) In the present invention, nylon-6 and nylon-66 can be used as the polyamide continuous filament yarn. Any fineness and number of filaments can be used, but for stockings it can be about 10 denier or more, for materials it can be up to about 400 denier, and from 2 filaments to 144 filaments. The first point of the present invention is that the maximum value F (grams) of dry heat shrinkage stress is 0.20D≧F≧0.08D. The F value of the conventional twisted yarn made of polyamide continuous filament is 0.06D or less. This F-value is related to the shrinkage force, and influences the shrinkage force in which the curl yarn is subjected to restraint in a fabric such as a woven or knitted fabric, but resists the restraint and develops a shrinkage. The present inventors have repeatedly conducted studies to improve the stretchability of woven or knitted fabrics using polyamide-based twisted yarns, and one of the requirements is to increase the ability of the twisted yarn to develop shrinkage in woven or knitted fabrics. Furthermore, they found that in order to increase this expression power, it was necessary to increase the F value. In particular, for applications such as tights and swimsuits that require high stretch, the F value must be 0.08D or higher. On the other hand, if the F value becomes too large, problems such as dimensional stability arise, and it is necessary that the F value is 0.20D or less. The second point of the present invention is that the heat treatment temperature T (° C.) at which the dry heat shrinkage stress reaches its maximum value is Tm≧T≧Tm−25. The T of conventional polyamide-based temporarily twisted yarn is about Tm-40, and there is a large difference from the melting temperature Tm. On the other hand, the difference between T and Tm of the polyamide temporarily twisted yarn of the present invention is small. The value of Tm is approximately constant once the polymer is determined. Therefore, if the polymers are of the same type, the polyamide pre-twisted yarn of the present invention has a higher T value. The T value affects the thermal stability of the temporarily twisted yarn. In this respect, the polyamide temporarily twisted yarn of the present invention has high thermal stability. The third point of the present invention is Ken shrinkage recovery rate CR (%)
is 15% or more. The CR value is a measure of the amount of shrinkage and is an essential element to have sufficient stretchability. Although it is preferable that the CR value is as large as possible, it is necessary that the CR value is 15% or more while satisfying the above two requirements. Above, the three requirements of the polyamide pre-twisted yarn according to the present invention have been individually described, but in order to achieve the preferred effects of the present invention described below, it is necessary to use a polyamide pre-twisted yarn that satisfies all of these requirements. There must be. The second invention in this application will be explained. As the temporary twisting machine according to the present invention, one having a feed roller group, a heat treatment device, a twisting device, and a winding device can be used, but as for the twisting device, the ratio of the unwrapped tension to the applied tension is 1.2 or less. It is preferable to use a pin twisting device, and a pin temporary twisting device is not preferable. In the present invention, it is necessary that the birefringence Δn of the polyamide continuous filament yarn fed to the temporary twisting machine is 35×10 ⁻³ or more. The method of the present invention can be carried out by supplying semi-drawn yarns and drawn yarns having birefringence within this range to a temporary twisting machine, or by continuously feeding undrawn yarns to a temporary twisting machine while being stretched. can. Next, in the second invention of the present application, it is necessary to set the applied tension t (grams/denier) to 0.8≧t≧0.4. The above range is considerably higher than the value taken in the conventional temporary twisting method.
In the case of pin twist, the value of t usually ranges from 0.10 to 0.12, and even in the case of friction twist, the value of t never exceeds 0.4. Generally, when the tension is increased, the release tension is also increased, resulting in a decrease in the shrinkage ratio, and it has been thought that the tension should be kept as small as possible within the range where processing stability is maintained. Although 0.8≧t≧0.4 in the present invention goes against this idea, a special combination with the heat set temperature H described below will produce a special effect that could not be predicted until now. be. In the method for producing a polyamide temporarily twisted yarn of the present invention, the heat setting temperature H (°C) must be within the range of Hm-10≧H≧Hm-25. Hm is the melting point (°C) of the supplied polyamide continuous filament yarn when it is drawn. The value of H generally adopted in the conventional temporary twisting method does not exceed Hm-30. The heat set temperature H corresponds to the surface temperature of the heater of the temporary twisting machine, but if the heater temperature is made extremely high, fusion will occur between the filaments and the yarn will not be processed. It was considered impossible to raise the heater temperature higher than Hm-25 when obtaining ordinary processed yarns. Hm-10≧H≧Hm-25 of the present invention is contrary to the above idea. That is, the added tension t (grams/denier)
Setting 0.8≧t≧0.4 or setting the heat set temperature H (°C) to Hm−10≧H≧Hm−25, respectively, may result in a low degree of densification and/or an appearance due to fused undissolved carbon. Only high-quality processed yarn could be obtained. However, they discovered the surprising fact that by combining the two, it is possible to obtain a pre-twisted yarn that is neither fused nor reduced in shrinkage, leading to the present invention. The method of the present invention has no limitations on the conditions other than the above, such as the temporary twisting speed, but the temporary twisting speed is 600 m/
It is particularly effective between min and 1000m/min. E. Functions and Effects of the Present Invention One of the effects obtained by the temporarily twisted yarn made of polyamide continuous filament yarn of the present invention is that the fabric product using the textured yarn has excellent stretch performance. It is. In other words, when knitting and weaving fabrics are dyed, the more the fabric can shrink sufficiently, the higher the stretchability of the fabric will be after dyeing. However, the temporary twisted yarn of the present invention has an extremely high maximum value F of shrinkage stress, and is difficult to stretch during the dyeing process. It has sufficient shrinkage power to overcome tension and the restraining force that acts between adjacent yarns within the knitted fabric, making it possible to obtain highly stretchy products. At the same time, it becomes a product with excellent elasticity. Furthermore, when the temporary twisted yarn of the present invention is used, the high stretchability of a product with excellent heat resistance can be maintained for a long time. In particular, woven or knitted fabrics are dyed and then finished and set, but at this time some of the stretchability of the woven or knitted fabrics is lost. When the temporary twisted yarn of the present invention is used, there is an advantage that such problems can be improved. Furthermore, polyamide-based temporarily twisted yarn is often used in combination with cotton yarn or acrylic spun yarn. These include socks, training wear, and sportswear. In this way, when inter-knitted with spun yarn with almost no stretchability, the temporary twisted yarn must have particularly high stretchability, but the temporary twisted yarn of the present invention can fully meet this requirement. . The advantage of the method for producing polyamide-based temporarily twisted yarn of the present invention is that it can be carried out without major modification of the equipment. Another advantage is that there are fewer restrictive conditions for increasing the temporary twisting speed. That is, in general, as the pre-twist processing speed increases, the rotational speed of the yarn increases, and as a result, the so-called ballooning phenomenon occurs in which the yarn rotates and vibrates at various parts of the yarn path.
Such ballooning reduces the stability of temporary twisting and causes yarn breakage and yarn unevenness. Therefore, the measure generally taken during high-speed temporary twisting is to increase the temporary twisting tension to suppress the occurrence of ballooning. However, if the tension is increased excessively, the shrinkage ratio of the tentative twist yarn decreases in the conventional technique, which is not preferable.
On the contrary, the method of the present invention is effective in a region where the applied tension t is high, and therefore it is an advantageous method for high-speed stable machining without the occurrence of ballooning. Example 1 Nylon-6 chips were melted by a conventional method, spun at a spinning speed of 5200 m/min, and wound onto a drum as it was to obtain a semi-drawn yarn of 89 denier and 24 filaments. The birefringence Δn of this semi-drawn yarn was 39×10 ⁻³ . Further, the melting point of the drawn yarn obtained by drawing this semi-drawn yarn by a conventional method was 217°C. This semi-drawn yarn is supplied to a drawing and pre-twisting machine manufactured by Murata Machinery Co., Ltd., and the processing speed,
Various pre-twisted yarns were prepared by changing the heat setting temperature and stretching ratio as shown in Table 1. The applied tension t (grams/denier) during the temporary twisting process obtained at this time is also shown in Table 1. Fineness (denier), strength (grams/denier), elongation (%), shrinkage recovery ratio CR (%), and maximum shrinkage stress F (grams) of the temporarily twisted yarn obtained by the above processing , heat treatment temperature T at which the shrinkage stress reaches its maximum value
(°C) and the melting temperature Tm (°C) are shown in Table 2. A 28G interlock knitted fabric was knitted using these pre-twisted yarns, and the stretch rate in the vertical direction, the appearance of the knitted fabric, and the tension after dyeing were evaluated. The results are shown in Table 2. Stretch rate was measured by the following method. Test procedure (1) Set up a 5cm x approximately 30cm test piece and collect three pieces from each side. (2) Using a constant-speed extension type tensile tester with a self-recording device, the grip distance is 20 cm, and an initial load equivalent to the weight of a 5 cm x 1 m sample is applied and fixed to the grips. (3) Stretched to 1.8Kg at a pulling speed of 20cm/min,
Measure the grip distance at that time (read to the nearest 1/2 mm). The elongation rate (%) is determined using the following formula and expressed as the average value of the three sheets (to one decimal place). Stretching rate (%) = l ₁ - l/l x 100 where l: Gripping interval (mm) l ₁ : Gripping interval when stretched to 1.8 kg (mm) As is clear from this table, the tentative twist of the present invention The processed yarn has excellent stretchability, knitted fabric appearance, and waist tension.

【table】

【table】

【table】 [Brief explanation of the drawing]

Figure 1 shows the maximum value F (grams) of dry heat shrinkage stress,
Heat treatment temperature T (℃) and melting temperature Tm at that time
It is a figure explaining (degree Celsius).

Claims (1)

[Claims] 1. Maximum value F of dry heat shrinkage stress in temporarily twisted yarn made of polyamide continuous filament yarn
(grams) and the heat treatment temperature T (℃) at which the dry heat shrinkage stress reaches its maximum value is 0.20D≧F≧0.08D Tm≧T≧Tm−25, and the shrinkage recovery rate CR (%) is 15%. A polyamide-based temporarily twisted yarn characterized by the above characteristics.
However, D is the fineness (denier) of the temporarily twisted yarn;
Tm is the melting temperature (°C). 2 After the polyamide continuous filament yarn is drawn, it is fed to a temporary twisting machine for twisting, heat setting, and unrolling, or alternatively, the polyamide continuous filament yarn is fed to a temporary twisting machine and stretched and twisted at the same time. In the method for producing a temporary twisted yarn that is thermally set and unrolled, the birefringence △n, the applied tension t (grams/denier), and the thermal setting temperature H (°C) of the polyamide continuous filament yarn supplied to the temporary twisting machine are determined. A method for producing a polyamide temporarily twisted yarn, characterized in that the processing is performed so that the following relationships are satisfied: △n≧35×10 ^-3 0.8≧t≧0.4 Hm−10≧H≧Hm−25. However, Hm is the melting point (°C) of the polyamide continuous filament yarn after drawing.