JP2006002305A - Weft knit fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weft knit fabric imparted with excellent stretch back property without deteriorating the handling feel of the fiber constituting the weft knit fabric. <P>SOLUTION: (1) The weft knit fabric has composite loops composed of (A) a latent crimping polyester fiber and (B) a fiber other than the latent crimping polyester fiber A wherein the latent crimping polyester fiber A is composed of two or more kinds of polyester components, one of the components is polytrimethylene terephthalate and the fiber A has an initial tensile resistance of 10-30 cN/dtex, a crimp elongation of developed crimp of 10-100% and a stretch modulus of 80-100%. The invention further provides (2) a weft knit fabric (1) wherein the latent crimping polyester fiber A is a false-twist yarn; (3) a weft knit fabric (1) wherein the inside of the composite loop is made of the latent crimping polyester fiber A and the outside is made of the fiber B; and (4) a weft knit fabric consisting of a flat knit fabric. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a weft knitted fabric, and more particularly to a weft knitted fabric imparted with excellent stretch back properties without impairing the texture of fibers constituting the weft knitted fabric.

A weft knitted fabric represented by a flat knitted fabric has a problem of imparting stretch properties from a recent stretch boom.
For imparting stretch properties, a method of knit polyurethane elastic fibers is common, but high stretch properties can be obtained, but the fibers that make up the weft knitted fabric are relatively dense and thick and heavy. There was a drawback that the texture of the was impaired. In addition, relatively high stretch properties can be obtained in the knitting of stretch materials represented by false twisted yarn of polytrimethylene terephthalate fiber and false twisted yarn of polybutylene terephthalate fiber. There was a problem that the texture of the constituent fibers was impaired.
Patent Document 1 discloses that high stretchability can be obtained by forming a composite loop using polytrimethylene terephthalate fiber and other fibers, but the stretch back property is not sufficient. It was.
JP 2002-20947 A

  An object of the present invention is to provide a weft knitted fabric to which excellent stretch back properties are imparted without impairing the texture of the fibers constituting the weft knitted fabric.

The invention claimed in the present application in order to achieve the above object is as follows.
(1) A weft knitted fabric having a composite loop composed of a latent crimpable polyester fiber (A) and a fiber (B) other than the latent crimpable polyester fiber (A), The latent crimp-expressing polyester fiber (A) is composed of two or more polyester components, one component of which is composed of polytrimethylene terephthalate, and satisfies the following (a) and (b): Weft knitted fabric.
(A) Initial tensile resistance is 10 to 30 cN / dtex
(B) The expansion / contraction elongation of the actual crimp is 10 to 100%, and the expansion / contraction elastic modulus is 80 to 100%.
(2) The weft knitted fabric according to (1), wherein the latent crimp-expressing polyester fiber (A) is false twisted yarn.
(3) The inner side of the said composite loop is comprised by the latent crimp expression polyester-type fiber (A), and the outer side is comprised by the fiber (B), (1) or (2) characterized by the above-mentioned Weft knitted fabric.
(4) The weft knitted fabric according to any one of (1) to (3), wherein the weft knitted fabric is a flat knitted fabric.

  The weft knitted fabric of the present invention has excellent stretch back properties without impairing the texture of the fibers constituting the weft knitted fabric.

Hereinafter, the present invention will be specifically described.
In the weft knitted fabric of the present invention, a latent crimp-expressing polyester fiber (A) and fibers (B) other than the latent crimp-expressing polyester fiber (A) are used.
The latent crimp-expressing polyester fiber (A) used in the present invention is composed of two or more polyester components, polytrimethylene terephthalate is used as at least one component, and crimps are developed by heat treatment. Examples of the fiber form composed of two kinds of polyester components include fibers joined in a side-by-side type and an eccentric core-sheath type, and the composite ratio is generally in the range of 70/30 to 30/70 by mass%. In addition, examples of the shape of the joint surface include a straight line or a curved shape, but are not limited thereto. The total fineness of the fiber (A) is preferably 20 to 550 dtex, more preferably 30 to 220 dtex, and the single yarn fineness is preferably 0.1 to 12 dtex, and particularly 1.5 to 6 dtex provides a soft texture. This is preferable.

Examples of such latent crimp-expressing polyester fibers (A) include polytrimethylene terephthalate disclosed in JP-A-2001-40537 as one component.
This fiber is a composite fiber in which two types of polyester polymers are joined in a side-by-side type or an eccentric core-sheath type. In the case of a side-by-side type, the melt viscosity ratio of the two types of polyester polymers is preferably 1.00-2. In the case of an eccentric core-sheath type, it is preferable that the sheath polymer and the core polymer have an alkali weight loss rate ratio that is three times or more faster than the sheath polymer.
Examples of the combination of the polyester polymer include a combination of polytrimethylene terephthalate and polyethylene terephthalate, and a combination of polytrimethylene terephthalate and polybutylene terephthalate. Particularly preferred is a polytrimethylene terephthalate disposed inside the crimp. .
These polymers are polyesters having terephthalic acid as the main dicarboxylic acid and 1,3-propanediol, ethylene glycol or 1,4-butanediol as the main glycol component, respectively, and other glycols such as ethylene glycol and butanediol. May be copolymerized with dicarboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid, and contains other polymers, matting agents, flame retardants, antistatic agents, pigments and other additives. Also good.

  Besides JP-A-2001-40537, JP-B-43-19108, JP-A-11-189923, JP-A-2000-239927, JP-A-2000-256918, JP-A-2000-328382 In Japanese Laid-Open Patent Publication No. 2001-81640, etc., the first component is polytrimethylene terephthalate, and the second component is a polyester such as polytrimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate in parallel or eccentrically. Disclosed is a composite spun to an arranged side-by-side type or eccentric sheath-core type. In particular, a combination of polytrimethylene terephthalate and copolymerized polytrimethylene terephthalate, or a combination of two types of polytrimethylene terephthalate having different intrinsic viscosities is preferable.

  In the present invention, the initial crimp resistance of the latently crimpable polyester fiber (A) is 10 to 30 cN / dtex, preferably 20 to 30 cN / dtex, more preferably 20 to 27 cN / dtex. The expansion / contraction elongation rate of the crimp is 10 to 100%, preferably 10 to 80%, more preferably 10 to 60%, and the elastic modulus of the actual crimp is 80 to 100%, preferably 85 to 100%, More preferably, it should be 85 to 97%. When the initial tensile resistance of the fiber (A) exceeds 30 cN / dtex, the texture of the fibers constituting the weft knitted fabric is impaired, and those having a fiber tension of less than 10 cN / dtex are difficult to manufacture. In addition, when the stretch elongation rate of the actual crimp of the fiber (A) is less than 10%, the stretch-back property is insufficient, and it is difficult to produce a fiber exceeding 100%. Furthermore, if the elastic modulus of the actual crimp of the fiber (A) is less than 80%, the stretch-back property is insufficient, and it is difficult to produce a fiber exceeding 100%.

In addition, the heat shrinkage stress at 100 ° C. of the latent crimpable polyester fiber (A) is preferably 0.1 to 0.5 cN / dtex, more preferably 0.1 to 0.4 cN / dtex, More preferably, it is 0.1-0.3 cN / dtex. When the heat shrinkage stress at 100 ° C. is less than 0.1 cN / dtex, the object of the present invention may not be sufficiently achieved, and it may be difficult to produce fibers exceeding 0.5 cN / dtex.
Furthermore, the stretch elongation after hydrothermal treatment of the latent crimpable polyester fiber (A) is preferably 100 to 250%, more preferably 150 to 250%, and most preferably 180 to 250%. If the stretch / elongation rate after the hydrothermal treatment is less than 100%, the object of the present invention may not be sufficiently achieved, and it may be difficult to produce fibers exceeding 250%. Moreover, 90-100% is preferable and the elasticity modulus after a hot-water process is 95-100% more preferably. If the elastic modulus after hydrothermal treatment is less than 90%, the object of the present invention may not be sufficiently achieved.

Examples of the latent crimp-expressing polyester fiber (A) having such characteristics include a composite fiber composed of a single yarn in which two types of polytrimethylene terephthalate having different intrinsic viscosities are combined in a side-by-side manner. .
The difference in intrinsic viscosity between the two types of polytrimethylene terephthalate is preferably 0.05 to 0.50 (dl / g), more preferably 0.10 to 0.45 (dl / g), and most preferably 0. .15 to 0.45 (dl / g). For example, when the intrinsic viscosity on the high viscosity side is selected from 0.70 to 1.30 (dl / g), the intrinsic viscosity on the low viscosity side is selected from 0.50 to 1.10 (dl / g). Is preferred.
The intrinsic viscosity on the low viscosity side is preferably 0.80 (dl / g) or more, more preferably 0.85 to 1.00 (dl / g), and most preferably 0.90 to 1.00 (dl / g). It is.
The intrinsic viscosity of the composite fiber itself, that is, the average intrinsic viscosity is preferably 0.70 to 1.20 (dl / g), more preferably 0.80 to 1.20 (dl / g). 0.85 to 1.15 (dl / g) is more preferable, and 0.90 to 1.10 (dl / g) is most preferable.
The value of intrinsic viscosity in the present invention refers to the viscosity of the spun yarn, not the polymer used. The reason for this is that polytrimethylene terephthalate is a disadvantage inherent to thermal decomposition as compared with polyethylene terephthalate and the like, and even if a polymer with a high intrinsic viscosity is used, the intrinsic viscosity is significantly reduced by thermal decomposition. This is because it is difficult to maintain a large difference in intrinsic viscosity between the two.

The polytrimethylene terephthalate is a polyester having a trimethylene terephthalate unit as a main repeating unit, and the trimethylene terephthalate unit is 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, most preferably 90 mol. The thing which contains more than%. Accordingly, as the third component, the total amount of other acid components and / or glycol components is 50 mol% or less, preferably 30 mol% or less, more preferably 20 mol% or less, and most preferably 10 mol% or less. Includes included polytrimethylene terephthalate.
Polytrimethylene terephthalate is synthesized by combining terephthalic acid or a functional derivative thereof with 1,3-propanediol or a functional derivative thereof in the presence of a catalyst under suitable reaction conditions. In this synthesis process, a suitable one or two or more third components may be added to form a copolyester. Polyesters other than polytrimethylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate, nylon and polytrimethylene. Methylene terephthalate may be synthesized separately and then blended. The content of polytrimethylene terephthalate during blending is 50% or more by mass%.

The third component to be added includes aliphatic dicarboxylic acids (oxalic acid, adipic acid, etc.), alicyclic dicarboxylic acids (cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (isophthalic acid, sodium sulfoisophthalic acid, etc.), fat Aliphatic glycols (ethylene glycol, 1,2-propylene glycol, tetramethylene glycol, etc.), alicyclic glycols (cyclohexanedimethanol, etc.), aliphatic glycols containing aromatics (1,4-bis (β-hydroxyethoxy) benzene Etc.), polyether glycol (polyethylene glycol, polypropylene glycol etc.), aliphatic oxycarboxylic acid (ω-oxycaproic acid etc.), aromatic oxycarboxylic acid (P-oxybenzoic acid etc.) and the like. In addition, compounds having one or three or more ester-forming functional groups (such as benzoic acid or glycerin) can also be used within the range where the polymer is substantially linear.
In addition, matting agents such as titanium dioxide, stabilizers such as phosphoric acid, ultraviolet absorbers such as hydroxybenzophenone derivatives, crystallization nucleating agents such as talc, easy lubricants such as aerosil, antioxidants such as hindered phenol derivatives, difficulty A flame retardant, antistatic agent, pigment, fluorescent whitening agent, infrared absorber, antifoaming agent, and the like may be contained.

Examples of the production method of the latent crimp-expressing polyester fiber (A) are disclosed in the various publications described above. For example, after obtaining an undrawn yarn at a winding speed of 3000 m / min or less, 2 to 3 Although the method of twisting at about 5 times is preferable, the straight-rolling method (spin draw method) in which the spinning-twisting process is directly connected, and the high-speed spinning method (spin take-up method) with a winding speed of 5000 m / min or more are adopted. May be.
The shape of the fiber may be uniform or thick in the length direction. The cross-sectional shape of the fiber is round, triangular, L-shaped, T-shaped, Y-shaped, W-shaped, Yaba-shaped, flat (flatness of about 1.3-4, W-shaped, I-shaped, Boomerang There may be a polygonal shape such as a shape, a corrugated shape, a skewer shape, an eyebrows shape, a rectangular parallelepiped shape, a dogbone shape, a multileaf shape, a hollow shape, or an indeterminate shape.

In the present invention, a false twisted yarn of the latent crimpable polyester fiber (A) is preferably used.
Any method such as a pin type, a friction type, a nip belt type, an air twist type, etc. can be used for false twisting of the latently crimped polyester fiber (A). Belt type. For the purpose of the present invention, it is preferable to use a so-called one-heater false twisted yarn (non-set type) rather than a so-called two-heater false twisted yarn (set type). The false twisted yarn is preferably a false twisted yarn obtained by drawing false twisted partially oriented undrawn yarn (POY) obtained by taking up at a winding speed of 2000 m / min or more, more preferably 2500 to 4000 m / min. .
The false twist heater temperature is preferably 100 to 200 ° C, more preferably 120 to 180 ° C, and most preferably 130 to 170 ° C, as the yarn temperature immediately after the exit of the first heater. The second heater temperature is preferably 100 to 210 ° C, more preferably in the range of -30 to + 50 ° C with respect to the yarn temperature immediately after the outlet of the first heater. The overfeed rate in the second heater is preferably + 3% to + 30%.

As for the number of false twists (T ₁ ), the value of the coefficient of false twist (K ₁ ) calculated by the following formula is preferably 21000 to 33000, and more preferably 25000 to 32000.
T ₁ (T / m) = K ₁ / [(fineness of raw yarn (dtex)] ^0.5
The false twisted yarn may be untwisted, but may be additionally twisted in the same direction as the false twist direction or in a different direction as necessary, or the false twisted yarn may be twisted with two or more twin yarns or S The false twisted yarn and the Z false twisted yarn may be twisted together. In particular, in the case of additional twisting or twisting, it is preferable to use a false twisted yarn obtained by drawing false twisted partially oriented undrawn yarn (POY) as described above.
The number of twists (T ₂ ) in additional twisting and twisting may be selected so that the twist coefficient (K ₂ ) calculated by the following formula is, for example, 20000 or less, preferably 1000 to 13,000. The total fineness of the false twisted yarn refers to the total fineness of the false twisted yarn to be additionally twisted or twisted.
T ₂ (T / m) = K ₂ / [Total fineness of false twisted yarn (dtex)] ^0.5

Other fibers may be mixed with the latent crimpable polyester fiber (A) as necessary. In that case, it is preferable to contain at least 20% of the latent crimpable polyester fiber (A) in mass%, more preferably 30% or more, and further preferably 50% or more. If it is less than 20%, a weft knitted fabric having good stretch back properties may not be obtained.
Examples of fibers mixed with the latent crimpable polyester fiber (A) include natural fibers such as cotton, wool (including Angola, cashmere, merino, etc.), hemp, silk, bamboo fiber, Japanese paper, cupra, and screw. Course, polynosic, purified cellulose, acetate, polyolefin fibers such as polyethylene and polypropylene, acrylate fibers, polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, various artificial fibers such as nylon and acrylic, and These copolymer types and composite fibers using the same or different polymers (side-by-side type, eccentric sheath core type, etc.) are available, and one or more of these are blended (core yarn, silospan, silofil, hollow spindle, etc.) , Covering (single, ), For example, a low shrinkage yarn having a boiling water shrinkage of about 3 to 10%, or a mixed yarn or a twisted yarn with a high shrinkage yarn having a boiling water shrinkage of about 15 to 30%, false twist (elongation difference false twist, POY (Compound etc. in stretch false twist)) You may mix by means, such as 2 feed air injection processing.

  As the fiber (B) used in the present invention, natural fibers such as cotton, wool (including Angola, cashmere, merino, etc.), hemp, silk, bamboo fiber, Japanese paper, cupra, viscose, polynosic, purified cellulose, acetate , Polyolefin fibers such as polyethylene and polypropylene, acrylate fibers, polyester fibers such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate, various artificial fibers such as nylon and acrylic, and their copolymer types and similar Or there are composite fibers (side-by-side type, eccentric sheath-core type, etc.) using different polymers, one or more of these are blended (core yarn, silospan, silofill, hollow spindle, etc.), covering (single, double), For example, boiling water shrinkage 3-1 % Of low shrinkage yarn or mixed with high shrinkage yarn, for example, boiling water shrinkage of about 15-30%, false twisting (false elongation false twisting, composite in POY stretch false twisting), 2-feed air You may mix and use by means, such as injection processing.

  The weft knitted fabric of the present invention has a composite loop composed of the above-described latently crimped polyester fiber (A) and fiber (B). In order to further emphasize the texture of the fiber (B), the composite It is preferable that the inner (back) side of the loop is composed of the latently crimpable polyester fiber (A) and the outer (front) side is composed of the fiber (B). The composite loop is preferably one in which 50% or more of the total number of knitted loops are uniformly distributed in the warp direction and the weft direction, more preferably 70% or more, still more preferably 75% or more, and most preferably 100%. It is. Here, the composite loop refers to the one in which the latent crimped polyester fiber (A) and the fiber (B) are supplied from separate packages to form a needle loop at the same time.

As a method of knitting the composite loop, the fiber (A) and the fiber (B) are aligned in front of the yarn feeder, and the composite loop is knitted at the same yarn feeder, and the fiber (A) and the fiber (B) are arranged on the needle. For example, a method of fixing the yarn feeding position relationship between the fiber (A) and the fiber (B) at the hook portion of the knitting needle by changing the yarn feeding angle. The former is the simplest method, but it is difficult to control the fiber (B) appearing on the surface of the knitted fabric, which may result in a composite loop in which the fiber (A) and the fiber (B) are mixed. The surface tends to have an uneven appearance. The latter is preferable because the positional relationship between the fiber (A) and the fiber (B) can be easily fixed, and the fiber (A) can be stably disposed inside the needle loop and the fiber (B) can be stably disposed outside. .
The weft knitted fabric of the present invention includes a flat knitted fabric and a circular knitted fabric, and is particularly effective in the flat knitted fabric.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. In addition, the measurement and evaluation in an example were performed by the following method.
1) Intrinsic viscosity [η] (dl / g):
It is a value obtained based on the definition of the following formula.
[Η] = lim (ηr−1) / C
C → 0
Ηr in the definition is obtained by dividing the viscosity of a diluted solution of polytrimethylene terephthalate yarn or polyethylene terephthalate yarn dissolved in an o-chlorophenol solvent with a purity of 98% or more at 35 ° C. by the viscosity of the solvent measured at the same temperature. Which is defined as relative viscosity. C is the polymer concentration expressed in g / 100 ml.
In addition, since it is difficult to measure the intrinsic viscosity of each composite multifilament using polymers having different intrinsic viscosities, two types of polymers are used under the same spinning conditions as the composite multifilament. The intrinsic viscosity measured using the yarn obtained by spinning alone was used as the intrinsic viscosity constituting the composite multifilament.
2) Initial tensile resistance (cN / dtex):
In accordance with JIS L 1013 Chemical Fiber Filament Thread Test Method Initial Tensile Resistance Test Method, a tensile test was performed by applying an initial load of 0.0882 cN / dtex per unit fineness of the sample, and an initial tensile force was obtained from the obtained load-elongation curve. The resistance (cN / dtex) is calculated. Ten samples are collected and measured, and the average value is obtained.
3) Stretch elongation rate and stretch modulus (%):
Measurement is performed according to the stretchability test method A of the JIS L 1090 synthetic fiber filament bulky processed yarn test method, and the stretch elongation rate (%) and the stretch elastic modulus (%) are calculated. Ten samples are collected and measured, and the average value is obtained.
The stretch elongation rate and the stretch elastic modulus of the actual crimp are measured after leaving the sample unwound from the winding package in an environment of a temperature of 20 ± 2 ° C. and a relative humidity of 65 ± 2% for 24 hours. For the stretchable elongation rate and the stretchable elastic modulus after the hot water treatment, a sample which is naturally dried for 24 hours with no load after being immersed in hot water at 98 ° C. for 30 minutes with no load is used.

4) Thermal contraction stress (cN / dtex):
Using a thermal stress measuring device (trade name KE-2, manufactured by Kanebo Engineering Co., Ltd.), the sample is cut to a length of 20 cm, both ends are connected, a ring is formed and loaded into the measuring device, and the initial load is 0.044 cN / dtex. The shrinkage stress is measured at a temperature rate of 100 ° C./min, and the heat shrinkage stress at 100 ° C. is read from the change curve of the heat shrinkage stress with respect to the obtained temperature.
5) Stretchability of flat knitted fabric:
The measurement was carried out in accordance with the method for measuring the elastic modulus of extension of JIS-L-1018 (A method: constant elongation method). That is, using a constant speed tensile tester with a self-recording device, using a test piece of 10 cm width × 15 cm length, applying an initial load of 2.942 cN, a grip width of 2.5 cm, a distance between grips of 10 cm, and a speed of 10 cm / It was extended until the elongation rate reached 100% in minutes, and left for 1 minute.
Thereafter, the film was contracted again at the same speed, a stress-strain curve was drawn, and the recovery rate was determined according to the following formula, where L (mm) was the residual elongation when the stress was the same as the initial load during contraction.
Recovery rate (%) = [(100−L) / 100] × 100
Stretchability was evaluated according to the following criteria from the recovery rate of the obtained flat knitted fabric.
A: The recovery rate exceeds 90%.
○: Recovery rate is 85% or more and less than 90% Δ: Recovery rate is 80% or more and less than 85% ×: Recovery rate is less than 70% 6) Texture of flat knitted fabric:
A sensory test was conducted by 10 skilled processing engineers, and the following ranking was performed in comparison with a flat knitted fabric using 100% of fiber (B), and an average value was evaluated.
3: It has the same texture as a flat knitted fabric using 100% of the fiber (B).
2: A slightly different texture compared to a flat knitted fabric using 100% of fiber (B).
1: It is quite different in texture from a flat knitted fabric using 100% fiber (B).

<Manufacture of Latent Crimp-Expressing Polyester Fiber (A)> Side-by-side composite multifilaments having different intrinsic viscosities were manufactured according to the following Production Examples 1 to 4.
(Production Example 1)
Two types of polytrimethylene terephthalate with different intrinsic viscosities are extruded into a side-by-side mold at a mass ratio of 1: 1 using a side-by-side compound spinning spinner, and undrawn yarn is spun at a spinning temperature of 265 ° C. and a spinning speed of 1500 m / min. Obtained. Next, the hot roll temperature is 55 ° C., the hot plate temperature is 140 ° C., the stretching speed is 400 m / min, the stretching ratio is set so that the fineness after stretching is 56 dtex, and the side-by-side type composite multifilament of 56 dtex / 12f is stretched. Obtained.
The resulting composite multifilament had an intrinsic viscosity of 0.90 on the high viscosity side and 0.70 on the low viscosity side. Table 1 shows the initial tensile resistance, the stretch elongation / stretch elastic modulus of the actual crimp, the stretch elongation / stretch elastic modulus after the hot water treatment, and the heat shrinkage stress at 100 ° C.

(Production Example 2)
A 56 dtex / 12f side-by-side composite multifilament was obtained in the same manner as in Production Example 1. The resulting composite multifilament had an intrinsic viscosity of 0.88 on the high viscosity side and 0.70 on the low viscosity side. Table 1 shows the initial tensile resistance, the stretch elongation / stretch elastic modulus of the actual crimp, the stretch elongation / stretch elastic modulus after the hot water treatment, and the heat shrinkage stress at 100 ° C.

(Production Example 3)
In Production Example 1, a 56 dtex / 12f side-by-side composite multifilament was obtained in the same manner as in Production Example 1 except that polytrimethylene terephthalate and polyethylene terephthalate having different intrinsic viscosities were used. The resulting composite multifilament had an intrinsic viscosity of 0.98 on the polytrimethylene terephthalate side and 0.60 on the polyethylene terephthalate side. Table 1 shows the initial tensile resistance, the stretch elongation / stretch elastic modulus of the actual crimp, the stretch elongation / stretch elastic modulus after the hot water treatment, and the heat shrinkage stress at 100 ° C.

(Production Example 4)
A 56 dtex / 12f side-by-side composite multifilament was obtained using two types of polyethylene terephthalate having different intrinsic viscosities. The intrinsic viscosity of the obtained composite multifilament was [η] = 0.66 on the high viscosity side and [η] = 0.50 on the low viscosity side. Table 1 shows the initial tensile resistance, the stretch elongation / stretch elastic modulus of the actual crimp, the stretch elongation / stretch elastic modulus after the hot water treatment, and the heat shrink stress at 100 ° C.

[Examples 1 to 3, Comparative Example 1]
Cotton yarn (cotton count 100 /-) was used as the fiber (B), and the composite filament obtained in each of Production Examples 1 to 4 was used as the fiber (A).
Using a 20-gauge automatic flat knitting machine (manufactured by Shima Seiki Seisakusho), knitting was performed by changing the yarn feeding angle with respect to the needle so that the fiber (B) was positioned outside the composite loop and the fiber (A) was positioned inside. . The ratio of the number of composite loops is 100%.
The texture of the obtained flat knitted fabric was excellent at 2.8 grade in Examples 1 and 2 and 2.5 grade at Example 3, but inferior at 1.5 grade in Comparative Example 1. It was a thing. In Examples 1, 2, and 3, the stretchability was satisfactory as ◎, but in Comparative Example 1, it was inferior as Δ.

[Comparative Example 2]
In Example 1, a flat knitted fabric was obtained by knitting in the same manner as in Example 1 except that a false trimmed yarn of polytrimethylene terephthalate fiber multifilament yarn was used as the fiber (A). The texture of the obtained flat knitted fabric was excellent at 2.7 grade, but the stretchability was inferior to that of Example 1 in comparison with Δ.

[Example 4]
In Example 1, a circular knitted fabric was obtained by knitting in the same manner as in Example 1 except that a 28 gauge circular knitting machine (manufactured by Fukuhara) was used. The texture of the obtained circular knitted fabric was as excellent as 2.7 grade, and the stretchability was satisfactory as ◎.

Since the weft knitted fabric of the present invention is excellent in stretch-back properties without impairing the original texture of the fiber, it is suitably used for outer clothing such as sweaters, collars and sleeves such as sports, inner clothing and polo shirts.

Claims (4)

A latent knitted fabric having a composite loop composed of a latent crimpable polyester fiber (A) and a fiber (B) other than the latent crimpable polyester fiber (A), the latent crimp The weft knitting characterized in that the expressible polyester fiber (A) is composed of two or more kinds of polyester components, one of which is composed of polytrimethylene terephthalate and satisfies the following (a) and (b): Earth.
(A) Initial tensile resistance is 10 to 30 cN / dtex
(B) The expansion / contraction elongation of the actual crimp is 10 to 100%, and the expansion / contraction elastic modulus is 80 to 100%.   The weft knitted fabric according to claim 1, wherein the latent crimpable polyester fiber (A) is a false twisted yarn.   The weft knitted fabric according to claim 1 or 2, wherein the inner side of the composite loop is composed of a latently crimped polyester fiber (A) and the outer side is composed of a fiber (B). The weft knitted fabric according to any one of claims 1 to 3, wherein the weft knitted fabric is a flat knitted fabric.