JPH0260765B2 - - Google Patents

Description

[Detailed description of the invention]

(Prior Art) The present invention relates to a raw yarn for stockings that has excellent high-speed knitting properties, elasticity, and abrasion resistance. Raw yarn for stockings includes elastic crimped yarn made from mechanically and thermally processed polyamide fibers, torque yarn made by strong twisting, polyurethane covering yarn made by covering polyurethane elastic yarn with polyamide fibers, and polyurethane covering yarns with different shrinkage characteristics. Self-crimpable two-component composite fibers, in which two components are joined in a centripetal manner within the cross-section of the fiber, have been proposed. Women's stockings are made by using these raw yarns as leg yarns or welt yarns, or knitting them alone, using plied yarns, or using mixed knitting on a seamless circular knitting machine or lattice knitting machine, etc., and then sewing them into stocking shapes. It is manufactured through processes such as dyeing, finishing, mold setting, etc. In recent years, the speed of the stocking knitting process has been increasing with the aim of increasing production efficiency. Taking a seamless circular knitting machine as an example, the rotation speed of the knitting machine used to be around 500 rpm, but now it is around 800 rpm.
~900rpm high-speed knitting machines are becoming common,
It is desired to develop a yarn for women's stockings that can be stably knitted on a high-speed knitting machine and has the elasticity, abrasion resistance, and transparency required for women's stockings. On the other hand, polyamide-based elastic crimped or torque yarns have excellent high-speed knitting properties, but have the drawback of insufficient stretch recovery due to crimping or strong twist torque, and lack of elasticity. Yes. In addition, polyurethane-based covering threads reflect the stretchability of the polyurethane elastic material, resulting in women's stockings with excellent stretchability. Because it is wound, the fineness of the yarn becomes large, which has the disadvantage that it cannot be used to make transparent women's stockings. On the other hand, many composite fibers have been proposed in which two components having different shrinkage properties are joined eccentrically within the fiber cross section. Among these, it has been proposed that self-crimping composite fibers made of polyurethane elastic material and polycapramide can be used to make women's stockings with particularly excellent elasticity (Japanese Patent Publication No. 10283/1983).
(Special Publication No. 55-36725, Publication No. 23926/1987). However, these yarns have insufficient adhesion between the polyurethane elastic body and polycapramide, and
There is a drawback that the two components peel off when wearing stockings (low wear resistance). As an improvement, a composite yarn using a polycarbonate-based polyurethane elastic material with good adhesion to polyamide (Japanese Patent Publication No. 55-22569, Japanese Patent Publication No. 55-22569,
Publication No. 22570, Special Publication No. 57-34369, Special Publication No. 1987
-34370 Publication), or a composite yarn (Japanese Patent Publication No. 55-27175) has been proposed in which the adhesiveness of the polyurethane elastic body and the peeling of the two components are improved by changing the cross-sectional shape to a thin-skinned eccentric core-sheath type. has been done. However, when these raw yarns undergo dyeing processing or heat treatment such as type setting after stocking knitting, not only does the knitted fabric shrink due to crimping, but the yarn also shrinks significantly in the fiber axis direction, resulting in insufficient product dimensions. There are disadvantages that cannot be avoided. In consideration of this drawback, Japanese Patent Publication No. 56-47281 proposes low-temperature finishing conditions. When this yarn is knitted on a seamless circular knitting machine as a leg yarn for stockings, it can be knitted without any major trouble at a knitting machine rotation speed of 200 to 400 rpm, resulting in a uniform product without knitting irregularities or skipped stitches. However, when the knitting machine rotates at a high speed of 800 to 900 rpm, thread breakage or skipped stitches occur, making stable knitting impossible. Stockings often have defects such as pulling or knitting spots, making it difficult to stably obtain a uniform product. (Problems to be Solved by the Invention) When a conventionally proposed self-crimping composite fiber consisting of polyurethane elastic material and polycapramide is used as leg yarn for women's stockings, and knitted at high speed conditions of 800 to 900 rpm. The reason why stable knitting and uniform products cannot be obtained is not clear, but it is thought to be due to the following reasons. (1) Conventional composite fibers made of polyurethane elastic material and polycapramide are made of polyurethane elastic material at room temperature so that self-crimping occurs simply by stretching after melt spinning, as described in Japanese Patent Publication No. 49-10283. The shrinkage force is extremely large, and stress is constantly acting on the fibers to cause them to shrink even under normal room temperature conditions. Therefore, even after it is rolled up into a cot or cheese shape, shrinkage stress acts gradually over time, and as a result, the yarn in the inner layer of the cheese or cot is crimped, resulting in poor unwinding properties during knitting. This causes yarn breakage or skipped stitches during high-speed knitting. (2) When such fibers are relaxed immediately after being stretched, they immediately develop a spiral crimp, but raw yarn wound into a knot or cheese shape is
As described in Japanese Patent No. 10283, crimp does not develop immediately after relaxation, but crimp develops after 1 to 2 minutes. Therefore, in the process of knitting women's stockings, the yarn is knitted as a flat yarn with no crimp at all. As is well known to those skilled in the art, for example, when polyamide flat raw yarn and polyamide crimped yarn are knitted at high speed, the polyamide crimped yarn is able to absorb slight fluctuations in raw yarn tension during the knitting process. It has better high-speed knitting properties than flat yarn because it absorbs elasticity and has good smoothness because the length of contact with guides or knitting needles is small. Such conventional raw yarn wound into a cot or cheese has self-crimping properties, but in the process of knitting women's stockings, it is in the form of a flat yarn and has poor high-speed knitting properties. (3) The product dimensions of women's stockings are determined by the dimensions when the crimps are stretched by applying a certain tension in the warp or weft direction. Therefore, for yarns that undergo large linear shrinkage during the heat process after knitting, the knitting dimensions must be increased. The polyamide crimped raw yarn has a low linear shrinkage rate of 5 to 7% when treated with boiling water, but such conventional yarn has a boiling water linear shrinkage rate of 20% or more.
The knitting dimensions must be made significantly larger. In the case of a seamless knitting machine, the dimensions during knitting are adjusted by changing the vertical movement width of the knitting needles.
With such conventional raw yarn, this vertical movement must be increased to increase the size of the stitches after knitting. However, the wider the range of vertical movement of the knitting needles, the more likely it is that skipped stitches will occur due to random tension fluctuations, and this tendency is particularly noticeable during high-speed knitting. It has the disadvantage of not being able to organize time. As a result of extensive research into composite filaments made of polyurethane elastomer and polycapramide in order to improve the above-mentioned drawbacks, the present inventor found that the composite filaments have a specific crimp type and are unraveled from cots and cheese.
The inventors have discovered that a stocking yarn that exhibits little change in crimp shape even when relaxed has excellent high-speed knitting properties and also provides good stocking performance in the final product, and has thus arrived at the present invention. (Means for Solving the Problems) The yarn for stockings of the present invention is a crimped composite fiber in which a polyurethane elastic body and a polycapramide are joined in a parallel type or an eccentric core-sheath type and has a circular cross-sectional shape. The polyurethane elastomer does not have a crosslinked structure due to a polyisocyanate compound in its molecules, the number of crimps is 5 or more/cm, the crimp width is 5 times or less than the fiber diameter, and the crimp elongation rate after release is 50%
It is characterized by the following: FIG. 1 is a view showing the crimped form of a conventional composite yarn made of polyurethane elastic material and polycapramide, and FIG. 2 is a view showing the crimped form of the raw yarn of the present invention. Conventional raw yarn is wound into a cot or cheese in the form of a flat yarn with no crimps, and when unwound from the cot or cheese, crimp gradually develops, resulting in a crimped form as shown in FIG. On the other hand, the raw yarn of the present invention is wound into a coppice or cheese with gentle wavy crimp as shown in FIG. Moreover, even if it is unwound from a cot or cheese and left under normal temperature and humidity conditions, there is almost no change in the crimp form. The number of crimps, which is an essential requirement for the yarn of the present invention, is 5 crimps/cm.
As mentioned above, when the crimp width is 5 times or less than the fiber diameter, it indicates the above-mentioned gentle wavy crimp, and preferably 8 crimp width or more and 2 to 4 times, respectively, and the crimp width after the fiber diameter is 5 times or less. A shrinkage/elongation ratio of 50% or less indicates that there is very little change in the crimp form even after unrolling from a cot or cheese, and preferably 40% or less. The number of crimp is less than 5/cm, the crimp width is more than 5 times the fiber diameter, and the crimp elongation rate after release is
If the raw yarn is larger than 50%, the unwinding tension will fluctuate greatly during high-speed knitting, which will not only cause weft steps in stockings, but also yarn breakage or skipped stitches. The boiling water shrinkage rate is preferably 7 to 17%. If it is more than 17%, it will shrink significantly in the heat process after knitting, resulting in insufficient product dimensions, while if it is less than 7%, sufficient winding will not be developed even if it is heat treated after knitting, and the stockings will lack elasticity. When the yarn of the present invention is wound into a cot or cheese, the winding hardness is preferably in the range of 55 to 85, particularly preferably 60 to 80, and the optimum winding hardness of ordinary nylon flat yarn is 90 to 100. Alternatively, the winding hardness is lower than the optimum winding hardness of nylon false twisted yarn of 85 to 90. When the raw yarn of the present invention is wound with a hardness greater than 85, the change in tension between the inner and outer layers of the cot or cheese becomes large, and the inner layer knitted product has a smaller knitted dimension than the outer layer knitted product. On the other hand, if the hardness is less than 55, the yarn may collapse during transportation. The raw yarn of the present invention is obtained by separately melting a thermoplastic polyurethane elastomer and a polycapramide, and then composite melt-spinning them into a parallel type or an eccentric core-sheath type. The film can then be produced by stretching, followed by a relaxation heat treatment under specific conditions as described below, and by rolling it into a cot or cheese. The polyurethane elastomer used in the present invention is a polyurethane elastomer having urethane bonds and urea bonds in the molecule, but an elastomer whose main component is polyhexamethylene carbonate as a soft segment is preferable. In addition, the polyurethane elastomer is made by melt-mixing a polyisocyanate compound during melt-spinning and then composite spinning to generate a crosslinked structure in the molecule (dissolution reduction rate in dimethylformamide is 80% by weight or less). It has excellent adhesive properties and is preferred. The polycapramide of the present invention is a polycondensate obtained by ring-opening polymerization of ε-caprolactam, and also includes a polymer obtained by copolymerizing 30 mol% or less of a component copolymerizable with ε-caprolactam. In the yarn of the present invention, the bonding weight ratio of the above-mentioned two components is preferably in the range of 7/3 to 3/7, and the yarns are bonded in a parallel type or an eccentric core-sheath type. Its cross-sectional shape is determined by the ratio (a/b) of the diameter of the circumscribed circle (denoted as a) and the diameter of the inscribed circle (denoted as b).
Shall be substantially circular with a diameter of less than 1.2. The relaxation heat treatment is preferably performed continuously at a relaxation rate that is 3 to 40% higher than the boiling water shrinkage rate measured for the drawn yarn. If the relaxation rate during the relaxation heat treatment is lower than the boiling water shrinkage rate of the drawn yarn, the crimping of the wound raw yarn will be weak, whereas if the relaxation rate is heat treated at a relaxation rate much higher than the boiling water shrinkage rate, the heat-treated yarn will have a spring. Small wavy crimps appear that are elongated. Relaxation heat treatment methods include a method in which the material is heated by running in a hollow tube heater using air as a heating medium, a method in which the material is heated by running on a hot plate, and the like. The method using a hollow tube heater has lower thermal efficiency than the method using a hot plate, requires setting at a temperature 50 to 70° C. higher than the hot plate method, and is more likely to cause heat treatment spots. Therefore, the method of hot plate heating is most suitable for the raw yarn of the present invention since there is no uneven heat treatment. In the method of relaxation heat treatment using a hot plate, the length L of the hot plate in contact with the raw yarn is
(m), the drawing yarn feed rate V (m/min) to the hot plate, and the surface temperature T (° C.) of the hot plate plate are preferably set within the range of the following formula. 1.8<L/V<12 90<T<140 L/V (min) is the parameter for the time the yarn is in contact with the hot plate, and if it is less than 1.8, heat treatment spots will occur and uniform yarn will not be obtained. . A method of increasing the heat treatment time is to increase the length of the heater, but if the heater length exceeds 12, the frictional force between the yarn and the heater tends to increase, and uneven crimp occurs in the yarn. comes out. If the heat treatment temperature is 90°C or lower, the heat treatment effect will be insufficient even if the heat treatment time is increased, and the boiling water shrinkage rate will increase. When the heat treatment temperature exceeds 140°C, the shrinkage force of the polyurethane elastic component decreases, and the crimp development force during the stocking process is insufficient, making it impossible to obtain good stretchability. In the present invention, it is preferable to wind up the yarn subjected to the relaxation heat treatment into a cot or cheese so that the winding hardness is 55 to 85. The winding hardness is adjusted by changing the tension during winding, and the optimal winding tension for the yarn of the present invention is 0.1 to 0.3 g per denier. The fineness of the single filaments constituting the raw yarn of the present invention is 3 to 30 d, and the number of filaments is 1 to 10.
For books, the total fineness is preferably 5 to 50 d. In particular, for stocking yarns that require transparency, it is desirable that the total fineness is 5 to 30 d and the number of filaments is 1 to 6. If the fineness of the single yarn forming the filament is less than 3d, the durability when wearing stockings is insufficient. On the other hand, if it is larger than 30d, the texture of the stockings will be stiff. The number of crimp, crimp width, and crimp elongation rate after unwrapping of the raw yarn of the present invention are as follows: Measurement is performed using the raw yarn that has been allowed to shrink over time as a sample using the following method. The number of crimps is determined by applying a load of 0.2 g/d to the sample, taking out a sample length of 5 cm, and then taking out a sample of 5 cm.
Measure the number of crimps in between and convert it to 1 cm. The crimp width and fiber diameter are measured under a microscope by sandwiching the sample between two glass preparations, or by taking a photograph and calculating it from the actual measurement of the photograph. In the present invention, the crimp width is L in FIG. 2, and the fiber diameter is d. The crimp elongation rate after deflation means that a skein equivalent to 1000 d is taken directly from a cot or cheese, and after being deflated to develop crimp under no load, a load of 200g is applied for 1 minute, and then a load of 200g is applied for 1 minute. After changing the load to 250 mg and leaving it for 2 hours, the length l ₀ of the skein was measured, and then the length l ₁ of the skein after applying a load of 200 g for 1 minute was measured, and the value was calculated using the following formula. Crimp extension rate after shrinkage (%) = l ₁ - _{l 0} / l ₀ × 100 The boiling water shrinkage rate is the length of the skein after 1 minute when a load of 200 g is applied to a skein of 1000 d directly taken from a coppice or cheese. Measure l ₂ . Next, it was immersed in boiling water for 15 minutes with a load of 250 mg applied, air-dried for 1 hour, and then the length _l3 of the skein was measured again under a load of 200 g and calculated using the formula below. Boiling water shrinkage rate (%) = l ₂ −l ₃ /l ₂ ×100 The winding hardness of the present invention is the arithmetic mean value of three or more measurements of the parallel portions of the koppu or cheese roll using a hardness meter. The raw yarn of the present invention is manufactured into stockings according to a conventional method, but in knitting, it can be used alone, or it can be doubled or cross-knitted with other elastic polyamide crimped yarns, polyurethane covering yarns, etc. You can also do it. (Effects of the Invention) The raw yarn of the present invention can be stably knitted without yarn breakage or stitch skipping even under high-speed knitting conditions of a stocking circular knitting machine with a knitting machine rotation speed of 800 to 900 rpm. In addition, knitting spots or variations in product dimensions due to fluctuations in unwinding tension occurring in the innermost layer of the soup or cheese do not occur. Moreover, the yarn of the present invention is
Since crimp has already appeared from the raw yarn stage, the stockings are shrunk to a small size immediately after knitting, and as a result, in the process after knitting, scratches due to mutual pulling of the products are less likely to occur. In addition, stockings with excellent elasticity, transparency, and durability can be obtained from the yarn of the present invention. EXAMPLES The present invention will be specifically explained below with reference to Examples. Example 1 Shore consisting of 70 parts of polyhexamethylene carbonate and 30 parts of polyhexamethylene adipate having a number average molecular weight of 2000 as a soft segment component, 4,4'-diphenylmethane diisocyanate as a diisocyanate compound, and 1,4-butanediol as a chain extender. - After separately melting a thermoplastic polyurethane elastomer having a hardness of 95 and polycapramide, the two components were joined in parallel at a joining weight ratio of 5/5, and an undrawn yarn of 30 d of single yarn was wound up. The undrawn yarn that has been wound is stretched at a stretching speed using a stretching machine equipped with a 20 cm long hot plate between two rollers (the first roller of the two rollers is a heating roller). 600m/min, stretching ratio
After stretching under the conditions of 3.50 times the heating roller and hot plate temperature as shown in the table below, winding is performed on a pirn with a winding hardness in the range of 80 to 75, and 20d/2f stocking yarns A, B, C, D was obtained (comparative example).

[Table] The appearance of yarns A, B, C, and D that were rolled up into cots did not show any crimp.
Spiral crimp developed within 1 to 2 minutes after release from the cot. The width of spiral crimp is A, B, C, D
They were the largest in order of size. Next, using the above-mentioned raw yarn A, using a relaxation heat treatment apparatus in which a 40 cm hot plate was installed between two rollers, the feed roller speed was 400 m/min.
The hot plate temperature was fixed at 120℃, and the pull-out roller speed was sequentially set to 340m/min, 300m/min, and 260m/min.
m/min, 220 m/min, and after the relaxation heat treatment, it was rolled up into a cot, and the relaxation rate during heat treatment was 15%, 25
Stocking yarn E equivalent to %, 35%, 45%,
F, G, and H were obtained. There was no crimp appearance in the appearance of yarn E with a relaxation rate of 15%, but yarns F, G, and H of the present invention had
Gentle wavy crimp appeared on the appearance of the tip. When the yarn was unwound from the cot, the yarn E was in the form of a flat yarn with no crimps immediately after unwinding, but curly crimps appeared after 1 to 2 minutes. On the other hand, yarns F, G, and H showed no change in crimp type even after being unwound from the copper, and all of them continued to exhibit gentle wavy crimp. The yarn qualities of these stocking yarns A to H are shown in Table 2.

【table】

[Table] As a result of knitting the above-mentioned stocking yarns A to H into leg parts using a 4-neck seamless stocking knitting machine at a knitting machine rotation speed of 900 rpm, the raw yarn F of the present invention,
G and H could be knitted without any problems, and the stocking quality was also good. On the other hand, yarns A, B, and C have a crimp elongation rate after release that is outside the invention, yarn D has a crimp width/fiber diameter outside the invention, and yarn D has a crimp number outside the invention. In E, stitch skipping, yarn breakage, or knitting steps caused by fluctuations in knitting tension occurred, and it was not possible to stably knit at 900 rpm. Example 2 The raw yarn B of Example-1 was placed between two rollers.
Heater temperature was changed to 80℃, 90℃, 120℃, 140℃, 150℃ using a relaxation heat treatment equipment equipped with a hot plate heater of do,
After the relaxation heat treatment, the yarn was wound into a cheese shape with a winding hardness in the range of 70 to 80 to obtain stocking yarns I, J, K, L, and M having different heat treatment temperatures. It was observed that gentle wavy crimp appeared in the cheese appearance of these raw yarns.
The fiber qualities of yarns I, J, K, L, and M are shown in Table 2. As a result of knitting yarns I, J, K, L, and M under the same conditions as in Example-1, all yarns could be knitted without any problems. Next, according to a conventional method, the dyed product was dyed at 95°C and mold-set with steam at 110°C to make women's stockings, and the performance of the stockings was evaluated. Both stockings had good transparency. The stockings made of yarn I, which has a high boiling water shrinkage rate, were slightly insufficient in size, and the stockings made from M, which had a small boiling water shrinkage rate, were slightly lacking in elasticity compared to yarns J, K, and L. Reference example: After separately melting a thermoplastic polybutylene adipate-based polyurethane elastomer with a hardness of 95 and polycapramide, the molecular weight of the polyurethane in the molten state is
4, at both ends of 800 ε-caprolactone diol.
A diisocyanate compound made by reacting 4'-diphenylmethane diisocyanate is melt-mixed, and then the polyurethane component and polycapramide are bonded at a polymerization ratio of 4/6, and an eccentric core-sheath type composite system in which polycapramide is a sheath and polyurethane is a core is melt-spun. Then I wound it onto a bobbin. Next, after being stretched 3.4 times at room temperature, it was subjected to a relaxation heat treatment under the same conditions as the yarn L of Example 2, and then rolled up with a winding hardness of 80 to obtain a stocking yarn N. Gentle wavy crimp was observed in the appearance of yarn N. The quality of yarn N is shown in Table 2. The raw yarn N was knitted and dyed under the same conditions as Example 1, and then finished into stockings through pattern setting.
There were no problems and the stockings had excellent transparency and elasticity.

[Brief explanation of the drawing]

FIG. 1 shows the crimped form of a conventional composite yarn made of polyurethane elastic material and polycapramide, and FIG. 2 shows the crimped form of the raw yarn of the present invention. In the figure, L is the crimp width and d is the fiber diameter.

Claims (1)

[Scope of Claims] 1. A crimped composite fiber in which a polyurethane elastic body and polycapramide are joined in a parallel type or an eccentric core-sheath type and has a circular cross-sectional shape, wherein the polyurethane elastic body is cross-linked in the molecule by a polyisocyanate compound. It has no structure and the number of crimp is 5/cm
As described above, the raw yarn for stockings is characterized in that the crimp width is not more than 5 times the fiber diameter and the crimp elongation rate after release is not more than 50%. 2. The yarn according to claim 1, wherein the bonded weight ratio of the polyurethane elastic body and polycapramide is 7/3 to 3/7. 3. The yarn according to claim 1, which has a boiling water shrinkage rate of 7 to 17%. 4. The raw yarn according to claim 1, which has a winding hardness of 55 to 85 and is wound into a cot or cheese.