JPH09291444A - Stretchable weft knitted fabric for under wear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stretchable weft knitted fabric manifesting an excellent dimensional stability while retaining stretchable character of the finished cloth, having additional soft feeling while retaining the character of cotton under wear and excellent processability by composing from respective specific elastic polyurethane filament and specific non-elastic filament forming the ground weave. SOLUTION: The ground weave is composed of the polyurethane elastic filament having excellent heat setting character at low temperature (the heat setting rate >=75% in 100% elongation at 140 deg.C for 1min) and the non-elastic filament containing 5-40% of fine acrylic filament of 0.3-0.9 denier, affording a soft feeling while retaining the feeling of a cotton under wear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weft knitted fabric used for underwear and the like, and more specifically to improve the soft feeling while maintaining the characteristics of conventional cotton underwear, and to make stretchable yarn into a weft knitted fabric. It is characterized in that it has elasticity when used in combination with the ground texture of the ground. Furthermore, by using the elastic yarn, it has good dimensional stability, stretchability, and soft-fitting type The purpose is to provide a method for efficiently producing land.

[0002]

2. Description of the Related Art Conventionally, acrylic fiber has been widely used as a material for innerwear by taking advantage of its unique softness and heat retention, but it is a mixed material due to thermal yellowing which is a drawback of acrylic fiber. There was a limitation. In particular, when general polyurethane elastic fibers are used as a mixed material to make the fabric elastic, the polyurethane elastic fibers have poor heat setting properties (dimensional stability) at low temperatures, and the pass rate of the finish fabric is low. Low. On the contrary, when set at a high temperature to improve the dimensional stability, the acrylic fiber is yellowed, which makes it impossible to produce efficiently. In addition, softness, which is one of the important required characteristics of underwear, knitted fabric using fine denier of acrylic fiber to give a soft feeling has the drawback that it feels too soft every time it is washed,
Moreover, there was a problem with dimensional stability in the dyeing process.

[0003]

DISCLOSURE OF THE INVENTION The present invention has improved the above-mentioned problems of the prior art, and in order to improve the production efficiency in the processing step while maintaining the elasticity of the finished fabric, the heat setting property at low temperature is provided. A polyurethane elastic fiber yarn having good (dimensional stability) is used, and fine denier acrylic fiber is mixed in order to add a soft feeling while taking advantage of the characteristics of conventional cotton underwear.

[0004]

The polyurethane elastic fiber having a good heat setting property (dimension stability) at low temperature used in the present invention is obtained by spinning a polyurethane elastomer composed of a high molecular diol, an organic diisocyanate and a low molecular diol. The resulting polyurethane filament yarn has a urethane group concentration of 1500 or more. Examples of the polymer diol used in the present invention include polytetramethylene glycol, poly ε-caprolactone, and polybutylene adipate. As the organic diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m-
Phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 2,4-
Examples thereof include naphthalene diisocyanate, m-xylene diisocyanate, 4,4′-diisocyanate dicyclohexane, 4,4′-diisocyanate dicyclohexylmethane, and isophorone diisocyanate. These may be used alone or in combination of two or more. Examples of the low molecular weight diol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl 1,3-
Propanediol, 3-methyl-1,5-pentanediol, 1,8-6 nandiol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, 1,4-bis (β-hydroxyethoxybenzene) and the like can be mentioned. To be These can be used alone or as a mixture of two or more kinds.

A known method is used for producing a polyurethane elastomer which is a raw material of the polyurethane elastic fiber in the present invention. For example, a one-shot method in which a high-molecular diol, a low-molecular diol, and an organic diisocyanate are reacted together in a solvent or without a solvent, or a high-molecular diol and an organic diisocyanate are reacted in advance to form a prepolymer, and then the low-molecular diol is used as a solvent. A prepolymer method or the like in which the reaction is carried out under a solvent or without a solvent. From the viewpoint of cost, the melt polymerization method which is produced without a solvent is desirable.

The urethane group concentration of the thermoplastic polyurethane elastomer in the present invention must be 1500 or more. When the urethane group concentration is less than 1500, the stretchability of the obtained yarn is not sufficiently exhibited. The urethane group concentration referred to here is, for example, 4,4′-diphenylmethane diisocyanate (M
When abbreviated as DI) is used, it is expressed by the following equation. Urethane group concentration = {(MDI charge amount / total raw material charge amount) ÷
125} × 10 ⁶ (equivalent / 10 ⁶ g)

Further, the polyurethane fiber yarn of the present invention is required to have a heat setting rate of 75% or more in dry heat treatment at 140 ° C. for 1 minute and 100% elongation. When the heat setting rate is lower than 75%, problems such as width defects are likely to occur in the dimensional stability in the preset step before dyeing. The dry heat setting property referred to here is a value measured by the following method. A load of 1 mg per denier of polyurethane elastic fiber is applied and L0 is taken as the sample length. Then, the sample is stretched twice and subjected to dry heat treatment (140 ° C. × 1 minute) in the stretched state, relaxed at room temperature for 1 hour, and then measured for a length L1 under a load of 1 mg / d. calculate. Heat setting rate (%) = (L1−L0) / L0 × 100

It is necessary that the non-stretchable yarn is a blended yarn containing 5 to 40% of ultrafine denier of acrylic fiber and 95 to 60% of cellulose fiber. The range of ultrafine denier is 0.3 to 0.9 denier, preferably 0.5 to 0.8 denier. Ultrafine yarns of less than 0.3 denier have low production operability and high cost. In addition, the processability in post-processing is also poor. If it is thicker than 0.9 denier, the characteristics cannot be obtained because it is not suitable for imparting a soft feeling to the cloth which is the object of the present invention. If the mixing ratio of the ultrafine fibers is less than 5%, a soft feeling is not imparted, and conversely, if it is more than 40%, the texture of the fabric becomes too soft, and the feeling is so strong that the tendency increases especially as the number of times of washing increases. . The material mixed with the acrylic ultrafine fibers is preferably hygroscopic cellulose fibers. Among them, cotton, which is often used for wearing on the skin, is preferable. The mixing ratio of cotton is set by the mixing ratio of acrylic ultrafine fibers which is determined by the demand for softness.

The acrylic ultrafine fibers and cellulose fibers are blended by a usual method to obtain a blended yarn. As a thread for wearing on the skin, a fluffed spun thread type is suitable because it has high required properties such as touch and hygroscopicity.

The non-stretchable yarns and the stretchable yarns are knitted by using a circular knitting machine in the same yarn feeding portion so that the stretchable yarns are not exposed on the front and back of the material. In this case, the stretchable yarn is fed by a positive yarn feeder to give 160 to 200% elongation, and in order to prevent the stretchable yarn from being exposed on the front and back of the fabric, It is necessary to feed the flexible yarn from the rear part of the non-stretchable yarn.

In the knitted fabric knitted under such conditions, the thickness of the non-stretchable yarn is preferably 2.5 times or more, more preferably 3 to 6 times thicker than the thickness of the elastic yarn. . This is because the main composition of stretchable yarn, polyurethane, is inferior to other materials in terms of light resistance, so the stretchable yarn is unevenly distributed inside the fabric as much as possible and covered with non-stretchable yarn to direct light. There is also the purpose of not exposing it and the purpose of not giving the rubbery slimy texture of polyurethane to the surface of the fabric. Further, in the knitted fabric, the mixing ratio of the stretchable yarns is set by the strength of the stretching force due to the required performance, but it is preferably in the range of 5 to 20%. If it is less than 5%, the stretching force is too weak to exert the effect. On the other hand, if it is more than 20%, the drape property of the cloth is deteriorated and the cost is also increased, which is not preferable.

The knitted fabric thus obtained is subjected to the usual steps of relaxing and scouring, and then, in the presetting step, the dry heat temperature is set in the range of 130 to 150 ° C. in accordance with the final target amount of 30.
Heat set within seconds to 2 minutes to stabilize dimensions. When the dry heat temperature is lower than 130 ° C in the step, the knitted fabric is inferior in dimensional stability and shrinkage properties, and when the dry heat temperature is higher than 150 ° C, thermal yellowing of the acrylic fiber or change in physical properties of the elastic yarn. It is not preferable because such problems are likely to occur. After presetting, dyeing is performed with a cationic dye or an acid dye. After that, heat setting is performed again in the finishing process, but the dry heat temperature is 120 to 1
It is performed within the range of 30 ° C. for 30 seconds to 2 minutes. The most important thing is to use conditions that are slightly looser than the heat setting conditions in the preset process.

According to the present invention, polyurethane elastic fibers having a good heat setting property at a low temperature are used, and fine denier acrylic fibers are mixed to maintain the stretchability of the finished fabric while maintaining the dimensional stability. In addition, it is possible to obtain an underwear weft knitted fabric that adds softness while taking advantage of the characteristics of conventional cotton underwear, and that has good production efficiency in the processing step.

The present invention will be described below with reference to examples. However, the present invention is not limited to this embodiment. In the examples,% means% by weight.

EXAMPLE 90% acrylonitrile, 9.8% methyl acrylate and 0.2 sodium methallylsulfonate.
% Of the polymer is dissolved in an aqueous solution of rhodanese, the spinning solution obtained is wet-spun in a coagulation bath, washed with water, stretched and heat-treated in a conventional manner to obtain staple fibers (single yarn denier 0 .8d) 10% and Egyptian cotton 9
A 50/1 s spun yarn was spun with a cotton count mixed with 0%. This is used as a non-stretchable yarn. On the other hand, polybutylene adipate for high molecular diol, 4,4'-diphenylmethane diisocyanate for organic diisocyanate,
A polyurethane elastomer obtained by polymerizing 1,4-butanediol as a low-molecular diol was spun to prepare a 20 denier monofilament. Urethane group concentration is 16
It was 00. This is used as a stretchable yarn.

The non-stretchable yarn and the stretchable yarn were set in a circular knitting machine having a diameter of 30 inches and a gauge of 20 and knitted as a rib knitting structure of 2: 1. At this time, the draft elongation rate (elongation rate) of the stretchable yarn was 2.5 times. The mixing ratio of the elastic yarn to the entire fabric was 7%.

The knitted fabric obtained was subjected to a relaxation treatment, followed by a scouring agent Marpon T 1 g / l, soda ash 0.5 g / l.
After carrying out the scouring treatment in the bath of No. 3, it was dry-heat set at a temperature of 135 ° C. for 30 seconds with a round setter. Bleaching with hydrogen peroxide water is carried out by a conventional method, and then, as a dyeing step, a cationic dye, a cationic desensitizing agent, and a leveling agent are used at 98 ° C ×
As a dyeing and finishing step for 90 minutes, 130 ° C. × 30 seconds was set in the same manner as in the preset step to obtain a stretchable knitted fabric for underwear. Table 1 shows the heat setting rate of the elastic yarns used, the property of the finished fabric, the heat yellowing, the washing shrinkage rate and the like.

(Comparative Example 1) Same as Example except that as the elastic elastic yarn, 20 denier 2-filament polyurethane elastic fiber dry-spun from polytetramethylene glycol, 4,4-diphenylmethane diisocyanate and ethylenediamine was used. The method and processing were performed under the same conditions to obtain a stretchable knitted fabric for wearing on skin. Table 1 shows the heat setting rate of the elastic yarns used, the property of the finished fabric, the heat yellowing, the washing shrinkage rate and the like.

(Comparative Example 2) As a stretchable elastic yarn, 20 denier 2-filament polyurethane elastic fiber dry-spun from polytetramethylene glycol, 4,4-diphenylmethane diisocyanate and ethylenediamine was used. A stretchable knitted fabric for underwear was obtained by processing under the same method and conditions as in Example except that the dry heat treatment was performed at a temperature of 60 seconds. Heat setting rate of the stretchable yarn used, the quality of finishing fabric, heat yellowing,
Table 1 shows the washing shrinkage ratio and the like.

(Comparative Example 3) As a non-stretchable yarn, the same method as in Example except that 50 / 1s spun yarn was used with cotton count in which the mixing ratio of acrylic fiber and Egyptian cotton was 45% and 55%. By processing under the same conditions, a stretchable knitted fabric for underwear was obtained. Table 1 shows the heat setting rate of the elastic yarns used, the property of the finished fabric, the heat yellowing, the washing shrinkage rate and the like.

In Comparative Example 1, since the heat setting property is low, the washing shrinkage rate is large and the dimensional stability is extremely poor. Comparative Example 2
Although it has good washing shrinkage and elongation characteristics, it is affected by thermal yellowing and hardening of the allyl fiber because it is set at a high temperature.
In Comparative Example 3, the heat setting rate of the elastic yarn is high and the washing shrinkage rate,
Good elongation properties, but high acrylic fiber content,
A slight yellowing is seen. As a particular drawback, it is too soft on the texture and has a strong "feeling".

Hereinafter, items not described in the detailed description of the present invention and the measuring methods used in Examples and the like will be described. (1) Heat yellowing The degree of yellowing of the dough after scouring and presetting is CEI-La.
The b * value was measured with a b * colorimeter [manufactured by Tokyo Denshoku Co., Ltd.]. (2) Washing shrinkage rate According to JIS-L1018 method, test piece length 25 cm,
Using 25 cm horizontal, the shrinkage rate of washing in the vertical and horizontal directions was measured. (3) Elongation rate, elongation recovery rate Elongation rate under constant load according to JIS-L1018 method (load 1 kg)
The elongation rate was measured using a measuring method. JIS-L1018
Elongation elastic modulus A method (constant elongation method) was used as the elongation recovery rate. 50% in the vertical direction and 100% in the horizontal direction
And

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to improve the problems of the prior art, improve the production efficiency in the processing step while maintaining the elasticity of the finished fabric. In addition, it is possible to make a new soft-fitting type underwear fabric that adds softness while taking advantage of the characteristics of conventional cotton underwear.

Claims (4)

[Claims] 1. In a weft knitted fabric in which a non-stretchable yarn and a polyurethane elastic fiber yarn form a ground structure, the non-stretchable yarn comprises 5 to 40% of acrylic fibers having a denier of 0.3 to 0.9 denier.
Polyurethane elastic fiber yarn has a heat setting rate of 7 at 140% x 1 minute and 100% elongation.
Stretchable flat knitted fabric for underwear, which comprises 5% or more yarns. 2. The non-stretchable yarn comprises a cellulosic fiber and a non-stretchable yarn.
The stretchable flat knitted fabric for underwear according to claim 1, which is a spun yarn made of acrylic fiber having a denier of 3 to 0.9. 3. The polyurethane elastic fiber yarn is a polyurethane filament yarn having a urethane group concentration of 1500 or more, which is obtained by spinning a polyurethane elastomer composed of a high molecular diol, an organic diisocyanate and a low molecular diol. The stretchable flat knitted fabric for wearing underwear according to claim 1. 4. In a weft knitted fabric in which a non-stretchable yarn and a polyurethane elastic fiber yarn form a ground structure, the thickness of the non-stretchable yarn is 2.5 times or more the thickness of the polyurethane elastic fiber yarn. And the mixing ratio of the polyurethane-based stretchable yarn is 5 to 20%.
The stretchable flat knitted fabric for underwear according to claim 1, wherein