JPS626027B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a knitted fabric with excellent shape stability. Conventionally, in order to reduce the torque of spun yarns containing polyester staple fibers, a method has been used in which the yarn is set in a cheese shape at a steam temperature of 60 to 130° C. to fix the twist. However, fixing the twist by this method is temporary, and even if a sufficiently set yarn is used, torque becomes apparent due to relaxation heat treatment after knitting. For example, commonly used polyester fibers
If 100% single yarn spun yarn is twisted and set at a steaming temperature of 120°C, the torque becomes almost zero, and a gray knitted fabric that is extremely easy to knit and has little diagonal can be obtained. However, since this knitted fabric is processed under high temperature conditions in the dyeing and finishing process, the torque of the yarn becomes apparent, which causes the knitted fabric to curl, reducing the ease of handling in the dyeing and finishing process and the sewing process. Furthermore, even after the product is manufactured, diagonal seams can be seen, resulting in a significant drawback in that the commercial value is significantly reduced. For this reason, it has been impossible to knit a twisted spun yarn containing polyester fibers into a single knitted fabric using a single yarn with only one twist direction. In order to eliminate these drawbacks, (1) a method of alternately arranging and knitting single yarns with different twist directions to prevent diagonal twisting, (2) using a twisted filament yarn as the core yarn of the core yarn, There are methods of neutralizing the twisting torque by imparting a twist opposite to this to the core yarn, but these methods are inferior in terms of cost and quality and are not widely and generally adopted. The present invention eliminates these drawbacks and provides a knitted fabric with excellent texture. That is, the present invention uses polyester fibers having a self-elongation rate of 3% or more at a dry heat temperature of 180°C.
A twisted blended yarn containing ~40%, the blended yarn is a single yarn, and the twist direction is one direction, is knitted into a single knitted fabric, and before and/or after the knitting. This is a method for producing a knitted fabric with excellent shape stability, characterized in that the blended yarn is heat-treated at a temperature of 100° C. or higher with wet heat or 150° C. or higher with dry heat. The present invention will be explained in detail below. The knitted fabric provided by the present invention is knitted using a blended yarn containing 10 to 40% of self-extensible polyester fibers, and it is particularly important to use self-extensible polyester fibers. be. The self-extending polyester fiber used in the present invention has the self-extending characteristics as shown in Figure 1, and preferably has a self-extending rate of 3% or more at a dry heat temperature of 180°C. This was obtained through experiments conducted by the present inventors. Such self-extensible polyester fibers have, for example, a birefringence index △n=0.02~0.02 obtained by high-speed spinning.
An undrawn polyester fiber bundle such as 0.08 is drawn at a temperature below [glass transition point +20°C] at the following draw ratio (DR). 0.04/△n+0.7≦DR≦0.04/△n+
1.1 Then, it can be obtained by performing a relaxation heat treatment at a temperature of 100°C to 140°C. The self-extensible polyester fiber obtained by the above method has an irreversible elongation rate of 3% or more at a dry heat treatment temperature of 180°C. The reason for using self-extensible polyester fibers here is as follows. Torque due to twisting of spun yarn causes curling and slanting of knitted fabrics, but most of this twisting torque is thought to be due to the fibers in the outer layer that make up the yarn. That is, as the yarn is twisted, the fibers in the outer layer are subjected to a larger strain, and the stress caused by this strain becomes a force in the untwisting direction, that is, a twisting torque. Therefore, with conventional blended yarns of thermoplastic synthetic fibers, heat treatment is applied to relieve the stress caused by strain and reduce the twisting torque, but as mentioned above, this is not sufficient. However, in the present invention, by using self-extending polyester fibers, the fibers that elongate during heat treatment actively relieve stress and reduce twisting torque. Next, the blending rate of the self-extensible polyester fiber used in the present invention is determined by the fibers to be blended. That is, when the material to be blended is itself a thermoplastic fiber such as a normal polyester fiber, the appropriate blending rate of the self-extensible polyester fiber is 10 to 40%. If the blending ratio is less than 10%, the effect of the elongated fibers will not be sufficient, and therefore the torque reduction during twisting will not be sufficient, and if the blending ratio exceeds 40%, the appearance and appearance of the knitted fabric will deteriorate. It cannot be used because the texture deteriorates. On the other hand, even when the fibers to be blended are thermoplastic fibers such as cotton, the blending ratio may be 10 to 40%, but preferably in the range of 20 to 40%. Furthermore, even when the fibers to be blended are a mixture of these fibers, the intended purpose can be achieved as long as the blending rate of self-extensible polyester fibers is in the range of 10 to 40%. In the method of the present invention, such a blended yarn is knitted into a single knitted fabric, and the blended yarn used is twisted and used in the form of a single yarn. Regarding the range of the number of twists, those used for ordinary spun yarns may be used, but the yarns are used in the form of single yarns, and the twist direction is unidirectional. Next, in the present invention, a blended yarn containing the above-mentioned self-extensible polyester fibers and/or a knitted fabric knitted with the blended yarn is heated at a temperature of 100°C or higher under wet heat or under dry heat.
It is necessary to heat treat at a temperature of 150°C or higher. The heat treatment temperature needs to be a temperature that exhibits self-extensibility, so a temperature of 100°C or higher is required for wet heat, and 150°C or higher for dry heat, and preferably 130°C or higher for wet heat.
℃ or higher, preferably at a dry heat temperature of 180℃ or higher. The step of carrying out the heat treatment may be carried out in the form of a thread, ie, a spinning koshipu, a winding thread, cheese, corn, or the like. Alternatively, the cheese-like fabric can be heat-treated at a relatively low temperature to temporarily fix the twist, then knitted, and when the knitted fabric is dyed and finished, it can be heat-treated in the heat-setting process or dyeing process. . Alternatively, the yarn may not be subjected to heat treatment at all, but may be subjected to dyeing and finishing after knitting. The knitted fabric obtained as described above did not curl during the dyeing and finishing process or the sewing process, and no diagonal stitches were observed even after it was made into a product, and its commercial value was significantly increased. Furthermore, since the self-extending fibers are elongated by heat treatment, a knitted fabric with excellent texture and no hardness can be obtained. This is particularly effective for single knitted fabrics knitted with one needle bed, such as dial needles such as Amagasa, or cylinder needles only. Next, examples of the present invention will be shown. [Example] A polyester tow with a birefringence index (△n) of 0.055, a single yarn denier of 2 de, and a total denier of 500,000 de is stretched 1.5 times in a hot water bath at 50°C, and crimped with a push crimper. The fibers were subjected to relaxation heat treatment at a dry and wet temperature of 140°C and cut with a cutter to obtain short fibers. The obtained polyester fiber has a dry heat resistance of 3.5 at a temperature of 180 °C.
% self-stretching rate. The above self-extensible polyester fibers are blended with ordinary polyester fibers and cotton, respectively.
No. 30 single yarn (English cotton count) was spun, and for comparison, No. 30 single yarn was spun from 100% ordinary polyester fiber and 100% cotton. After twisting and setting these yarns with steam at 130°C, jersey was knitted using a 20-cage knitting machine. This knitted fabric was treated with boiling water for 10 minutes, and the degree of obliqueness before and after the treatment was measured. The results are shown in Table 1. 【table】

[Brief explanation of the drawing]

FIG. 1 is a self-extension characteristic curve diagram of the polyester fiber used in the present invention.

Claims (1)

[Claims] 1 A twisted blended yarn containing 10 to 40% of polyester fibers having a self-elongation rate of 3% or more at a dry heat temperature of 180°C, where the blended yarn is a single yarn and the twist direction is unidirectional. knitted into a single knitted fabric using
A method for producing a knitted fabric with excellent shape stability, characterized by heat-treating the blended yarn as described above at a temperature of 100°C or higher, or a dry heat temperature of 150°C or higher.