double knit fabric

Abstract

To provide a double knit fabric that provides a better wearing feeling. [Solution] A double knit fabric knitted with inelastic yarn and polyurethane elastic yarn, in which the peak value of thermal stress for the inelastic yarn removed from the double knit fabric after the grey fabric has been heat-treated is 30% or more and 40% or less of the peak value of thermal stress for the inelastic yarn removed from the double knit fabric when it is still in the grey state, and the product of warp density and weft density is 4000 / square inch or more.

Description

[Technical Field]

[0001] The present invention relates to a double knit fabric that has high elongation and high recovery and can be used for clothing and the like. [Background technology]

[0002] A double knit fabric is known that is knitted by plating inelastic yarn and elastic yarn. Such double knit fabrics have high elongation and high recovery properties and are used in clothing and the like.

[0003] One known double knit fabric in which non-elastic yarn and elastic yarn are knitted together by plating is the double knit fabric described in Patent Document 1. This double knit fabric not only has high elongation and high recovery, but also is resistant to run and curl and has a good texture, thanks to the ingenuity of the heat deformation onset temperature of the non-elastic yarn, the fineness ratio of the non-elastic yarn to the elastic yarn, and the product of the warp density and the weft density. For this reason, this double knit fabric has been well received as a double knit fabric suitable for clothing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5241716 Summary of the Invention [Problem to be solved by the invention]

[0005] Although double knit fabrics suitable for clothing exist as described above, there is a demand for knit fabrics that provide a better wearing feel (feeling of tightness and stretch when worn) when used in clothing.

[0006] Therefore, an object of the present invention is to provide a double knit fabric that provides a better wearing feeling. [Means for solving the problem]

[0007] The present invention includes the embodiments shown below.

[0008] [1] In a method for manufacturing a double knit fabric containing a non-elastic yarn and a polyurethane elastic yarn, a green machine containing the non-elastic yarn and the polyurethane elastic yarn is knitted, and the green machine is heat-treated, so that the peak value of the thermal stress of the non-elastic yarn taken out of the double knit fabric after the green machine has been heat-treated is 30% or more and 40% or less of the peak value of the thermal stress of the non-elastic yarn taken out of the green machine before the heat-treatment, The heat treatment includes a heat set and a final set that is performed after the heat set, and the final set has a temperature of 130°C or higher and 170°C or lower and a treatment time of 50 seconds or higher and 70 seconds or lower; The double knit fabric after the heat treatment And, The product of longitudinal density and weft density is 4000 / square inch or more. The cover factor of the non-elastic yarn is set to 7 or more and 15 or less, and the cover factor of the polyurethane elastic yarn is set to 2 or more and 5 or less. A method for manufacturing double knit fabric.

[0009] [2] By carrying out the heat treatment, The breaking strength of the non-elastic yarn taken out from the double knit fabric in the grey state do , the said grey fabric The aforementioned Breaking strength of the inelastic yarn taken out from the double knit fabric after heat treatment of , 70% or more Let's say The double knit fabric according to [1] Manufacturing method .

[0010] [3] In the double knit fabric after the heat treatment Peel strength between the polyurethane elastic threads of 7cN or more Let's say The double knit fabric according to [1] or [2] Manufacturing method .

[0012] [ 4 By carrying out the heat treatment, the elastic modulus of the inelastic yarn taken out from the double knit fabric after the grey fabric has been heat treated is set to 50% or more and 70% or less of the elastic modulus of the inelastic yarn taken out from the double knit fabric when the grey fabric is in the state of being the grey fabric. [1] to [ 3 ] A method for producing a double knit fabric according to any one of the preceding items. [Effects of the Invention]

[0013] The double knit fabric described above provides a more comfortable wearing experience when used in clothing, as the ratio of the peak value of thermal stress and the product of the warp density and the weft density fall within a predetermined range. [Brief explanation of the drawings]

[0014] [Figure 1] Knitting diagram of interlocking fabric. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following describes an embodiment. Note that the embodiment described below is merely an example, and any appropriate modifications that do not deviate from the spirit of the present invention are included in the scope of the present invention.

[0016] The double knit fabric of this embodiment is a weft knitted fabric, and more specifically, a circular knitted fabric, which is a type of weft knitted fabric. The double knit fabric of this embodiment is knitted with a non-elastic yarn and a polyurethane elastic yarn. Preferably, the double knit fabric of this embodiment is knitted with a non-elastic yarn and a polyurethane elastic yarn by plating (plated knitting). In a double knit fabric knitted with a non-elastic yarn and a polyurethane elastic yarn by plating, loops (stitches) in which the non-elastic yarn and the polyurethane elastic yarn overlap are aligned in the weft and warp directions on both the front and back sides. The alignment of loops in which the non-elastic yarn and the polyurethane elastic yarn overlap in the weft and warp directions gives the double knit fabric elongation and recovery. The alignment of loops in which the non-elastic yarn and the polyurethane elastic yarn overlap on both the front and back sides improves the balance of tension between the front and back sides, making curling less likely. Preferably, after plating knitting, the non-elastic yarn appears on the surfaces of both the front and back sides of the double knit fabric, and the polyurethane elastic yarn is positioned on the inside of the double knit fabric. In the double knit fabric of this embodiment, it is preferable that the inelastic yarn and the polyurethane elastic yarn overlap in all loops.

[0017] Furthermore, the specific structure of the double knit fabric is not limited. Specific structures include punch and mesh structures. One preferred structure is the interlock structure shown in Figure 1. When the double knit fabric is made of an interlock structure, both the front and back surfaces are smooth and, since the front and back surfaces have the same structure, a double knit fabric that is less likely to curl is obtained. In Figure 1, F1 and F2 respectively represent yarn feeders, and the solid line indicating the movement of the yarns represents the overlapping of the inelastic yarn 1 and the polyurethane elastic yarn 2.

[0018] Examples of inelastic yarns used in double knit fabrics include yarns made from synthetic fibers such as nylon, polyethylene, polyester, acrylic, and polyvinyl alcohol; yarns made from regenerated fibers such as rayon; and yarns made from natural fibers such as cotton, linen, wool, and silk. Nylon yarns or polyester yarns are preferred. Furthermore, nylon yarns and / or polyester yarns may be used in double knit fabrics, and may also be interwoven with other inelastic yarns. In other words, it is preferred that double knit fabrics contain nylon yarns or polyester yarns as inelastic yarns.

[0019] Furthermore, the polyurethane elastic yarn used in double knit fabrics is preferably a bare polyurethane elastic yarn (bare spandex) that is not covered with other yarns. If the polyurethane elastic yarn is bare spandex, it will easily bond with the surrounding yarns, making the double knit fabric less likely to fray.

[0020] The ratio of the fineness of the polyurethane elastic yarn to the non-elastic yarn used in the double knit fabric is preferably 1:0.3 to 1:3.0. When the ratio of the non-elastic yarn fineness to the polyurethane elastic yarn fineness is 0.3 or more, the loose weave characteristic of polyurethane elastic yarn is less likely to occur and the texture tends to be good. When the ratio of the non-elastic yarn fineness to the polyurethane elastic yarn fineness is 3.0 or less, run is particularly less likely to occur.

[0021] The grey double knit fabric is knitted by a knitting machine. When the double knit fabric is a circular knit fabric, the grey double knit fabric is knitted by a double circular knitting machine equipped with dial needles and cylinder needles. The gauge of the double circular knitting machine is determined according to the density of the double knit fabric. The needle arrangement method of the double circular knitting machine is also determined according to the knitting structure.

[0022] Various treatments including heat treatment are performed on the knitted grey fabric. Here, examples of various treatments including heat treatment will be described.

[0023] First, the knitted grey fabric is heat-treated (so-called heat-set). The heat-treatment temperature (not the set temperature but the actual temperature) is preferably 180°C to 200°C, more preferably 190°C to 195°C, and particularly preferably 195°C. The heat-treatment time at these temperatures is preferably 40 seconds to 100 seconds, and particularly preferably 90 seconds. This heat-treatment bonds the surrounding polyurethane elastic yarns together, making the double knit fabric less susceptible to run, curl, and fraying. The heat-treatment temperature is set to the above range, which is effective in achieving desirable values ​​for the retention rate of the thermal stress peak value of the non-elastic yarn, the retention rate of the breaking strength of the non-elastic yarn, the peel strength of the polyurethane elastic yarn, and the retention rate of the elastic modulus of the non-elastic yarn, which will be described later.

[0024] After heat setting, the double knit fabric is dyed. After dyeing, the double knit fabric is subjected to final setting. The temperature for final setting is lower than the temperature for the heat treatment described above, and although it depends on the type of yarn, it is, for example, 130°C or higher and 170°C or lower, and preferably 130°C or higher and 150°C or lower. The treatment time at these temperatures is, for example, 50 seconds or higher and 70 seconds or lower. The final setting corrects distortion of the structure and finalizes the dimensions and density of the double knit fabric. The double knit fabric is completed through the above-mentioned processes.

[0025] Unless otherwise specified, the following descriptions are for double knit fabrics that have been completed through various treatments, including heat treatment. In the following description, the double knit fabric that has been completed through various treatments, including heat treatment, may be referred to as the double knit fabric as a finished product.

[0026] The double knit fabric of this embodiment preferably has an elongation percentage of 150% or more and an elongation recovery percentage of 85% or more. The elongation percentage is a numerical value indicating the degree of elongation, and the elongation recovery percentage is a numerical value indicating recovery. By having such an elongation percentage and elongation recovery percentage, the double knit fabric provides a good wearing comfort when used in clothing.

[0027] Here, the elongation percentage is measured by the following method. Three test pieces measuring 16 cm in the warp direction and 2.5 cm in the weft direction and three test pieces measuring 2.5 cm in the warp direction and 16 cm in the weft direction are cut from the circular knitted fabric. The 16 cm test pieces are used to measure the elongation percentage in the warp direction, and the 16 cm test pieces are used to measure the elongation percentage in the weft direction. Measurements are performed using a known constant-rate extensometer tensile tester. Specifically, the test piece is gripped with a chuck jig with a toothed gripping portion, with an upper grip length of 2.5 cm, a lower grip length of 3.5 cm, and a chuck spacing of 10 cm. The test piece is then pulled at a pulling rate of 30 cm / min, and the elongation percentage at a load of 14.7 N is measured. The elongation percentages of three test pieces in the same direction are measured, and the average value is taken as the elongation percentage in that direction.

[0028] The elongation recovery rate is measured by the following method. First, two test pieces, one measuring 16 cm in the warp direction and 2.5 cm in the weft direction and the other measuring 2.5 cm in the warp direction and 16 cm in the weft direction, are cut out from the circular knitted fabric. The 16 cm test piece in the warp direction is used to measure the elongation recovery rate in the warp direction, and the 16 cm test piece in the weft direction is used to measure the elongation recovery rate in the weft direction. The cut test pieces are gripped in the same way as when measuring the elongation rate, using the same testing machine as when measuring the elongation rate. Then, the test piece is stretched to 80% of the chuck gap at a pulling speed of 30 cm / min and then allowed to recover, repeating this process three times, and an elongation recovery curve is drawn. The residual elongation is read from the elongation recovery curve, and the elongation recovery rate is calculated using the following formula.

[0029]

number

[0030] Here, RA is the elongation recovery rate, L is the set elongation of 80%, and L0 is the residual elongation.

[0031] Furthermore, the peak thermal stress value of the inelastic yarn taken out of the double knit fabric as a finished product is 30% to 40% of the peak thermal stress value of the inelastic yarn taken out of the double knit fabric as a grey fabric. This ratio is defined as the maintenance rate of the peak thermal stress value.

[0032] The thermal stress peak value retention rate indicates the degree of heating of the gray fabric, and the lower the thermal stress peak value retention rate, the more the double knit fabric is affected by heat. A thermal stress peak value retention rate of 40% or less means that the double knit fabric is affected by heat to some extent, making it less likely to fray or curl. A thermal stress peak value retention rate of 30% or more means that the double knit fabric is not affected by heat excessively, resulting in high elongation and high recovery, and a better wearing comfort when used in clothing.

[0033] Here, the thermal stress peak value is measured in accordance with JIS L 1095. Specifically, 10 cm long inelastic yarns are taken from the double knit fabric grey and the double knit fabric as a finished product to serve as samples. The sample is fixed with a hook, and a constant load is applied in the pulling direction of the sample. In this state, the sample is heated from 30°C to 240°C. The stress generated in the sample during the temperature rise is measured, and a curve showing the change in stress with temperature is drawn. The stress value at the peak of the curve is the thermal stress peak value. The thermal stress peak value is the measured stress divided by the fineness of the yarn used as the sample, and is expressed in cN / dtex.

[0034] In the double knit fabric, the cover factor of the inelastic yarn is 7 or more and 15 or less, and the cover factor of the polyurethane elastic yarn is 2 or more and 5 or less. The cover factor is calculated using the following formula, with the value rounded off to the nearest whole number.

[0035]

number

[0036] Here, K is the cover factor, L is the length of the yarn for 100 loops, and D is the denier (1 denier = 9 / 10 dtex). When the cover factors of the inelastic yarn and polyurethane elastic yarn are within the above ranges, the binding force of the loops in the double knit fabric becomes appropriate, making the loops less likely to come undone and ensuring the elongation and recovery of the double knit fabric.

[0037] Furthermore, the product of the warp density and weft density of the double knit fabric is 4000 / square inch or more. The warp density is the number of loops per inch of length in the warp direction, and the weft density is the number of loops per inch of length in the weft direction. The warp density is preferably 80 courses / inch or more, and the weft density is preferably 50 wefts / inch or more. When the product of the warp density and weft density is 4000 / square inch or more, the double knit fabric tends to have high elongation and high recovery. Furthermore, when the double knit fabric is stretched in the warp and weft directions, the tension applied per loop is reduced, making run less likely to occur.

[0038] Furthermore, the breaking strength of the inelastic yarn extracted from the double knit fabric as a finished product is preferably 70% or more, and more preferably 70% or more but less than 85%, of the breaking strength of the inelastic yarn extracted from the double knit fabric in the grey state. This ratio is referred to as the breaking strength retention rate. The breaking strength retention rate indicates the degree of heating of the grey fabric, and a lower breaking strength retention rate indicates a greater thermal impact on the double knit fabric. A breaking strength retention rate of 70% or more means that the double knit fabric has not been excessively affected by heat, which allows the double knit fabric to have high elongation and high recovery. A breaking strength retention rate of less than 85% means that the double knit fabric has been affected by heat to some extent, which makes the double knit fabric less susceptible to fraying or curling.

[0039] In measuring the breaking strength, inelastic yarns are taken out from the grey double knit fabric and the finished double knit fabric, respectively. The breaking strength is the force at which the taken-out inelastic yarns are pulled and break, and is measured in accordance with JIS L 1096.

[0040] In the double knit fabric, the peel strength at the contact points between the polyurethane elastic yarns is preferably 7 cN or more. This peel strength of 7 cN or more makes the double knit fabric less susceptible to run, curl, and fraying.

[0041] Furthermore, it is preferable that the modulus of elasticity of the inelastic yarn extracted from the double knit fabric as a finished product is 50% or more and 70% or less of the modulus of elasticity of the inelastic yarn extracted from the double knit fabric when it is still in the green state. This ratio is referred to as the modulus retention rate. The modulus retention rate indicates the degree of heating of the green fabric, and a lower modulus retention rate indicates a greater thermal effect on the double knit fabric. An modulus retention rate of 50% or more means that the double knit fabric is not excessively affected by heat, which allows the double knit fabric to have high elongation and high recovery. An modulus retention rate of less than 70% means that the double knit fabric is affected by heat to some extent, which makes the double knit fabric less susceptible to fraying.

[0042] To measure the modulus of elasticity, inelastic yarns are extracted from both the grey double knit fabric and the finished double knit fabric. The modulus of elasticity is measured according to JIS L 1096. Specifically, the elongation stress of the inelastic yarn is measured while gradually increasing the elongation of the inelastic yarn (i.e., gradually stretching the inelastic yarn). Based on the increase in elongation stress as the elongation changes from 1.0% to 1.4% (i.e., as the length of the inelastic yarn changes from 101.0% to 101.4% of its pre-stretching length), the increase in elongation stress per 1.0% increase in elongation is calculated, and this calculated value is the modulus of elasticity. In other words, when the measurement results are graphed with the horizontal axis representing elongation and the vertical axis representing elongation stress, the slope of the graph over the elongation range from 1.0% to 1.4% represents the modulus of elasticity. A high modulus of elasticity indicates that the yarn is less likely to deform, while a low modulus of elasticity indicates that the yarn is more likely to deform.

[0043] The various numerical ranges described above can be combined in any manner, and each combination is a preferred embodiment.

[0044] The double knit fabric of this embodiment can be used for clothing, etc. The double knit fabric of this embodiment has high elongation and high recovery, so when made into clothing, a better wearing feel is obtained. Furthermore, the double knit fabric of this embodiment is less likely to fray or curl, so it can be used in a cut-off state.

[0045] Next, the effects of this embodiment will be described. The double knit fabric of this embodiment is knitted with inelastic yarn and polyurethane elastic yarn, and has a newly noted physical property, the thermal stress peak value retention rate of the inelastic yarn, of 30% to 40%, and the product of warp density and weft density is 4000 / in2 or more. In this way, due to the new combination of the new yarn characteristic, the thermal stress peak value retention rate, and the fabric characteristic, the product of warp density and weft density, the double knit fabric of this embodiment provides a good wearing feel and is less likely to fray or curl.

[0046] Furthermore, such double knit fabrics have one or more of the following characteristics in combination: a newly focused physical property of breaking strength retention of 70% or more; a newly focused physical property of elastic modulus retention of 50% or more and 70% or less; a peel strength between polyurethane elastic yarns of 7 cN or more; and a cover factor of the inelastic yarn of 7 or more and 15 or less, and a cover factor of the polyurethane elastic yarn of 2 or more and 5 or less, thereby providing a more comfortable wearing experience.

[0047] Next, an example will be described.

[0048] (1) Manufacturing of double knit fabrics A double circular knitting machine was used to plate knit inelastic yarn and polyurethane elastic yarn to produce a double knit fabric. The knitted fabric was heat-treated at a predetermined heat treatment temperature. Then, dyeing and final setting were carried out to obtain a double knit fabric as a finished product. Fabrics 1 to 3 shown in Table 1 were obtained as double knit fabrics.

[0049] [Table 1]

[0050] (2) Thermal stress peak value retention rate Inelastic yarns were taken from the grey fabric and the double knit fabrics as finished products that had been heat-treated at each temperature, and the thermal stress peak value of each inelastic yarn was measured. The method for measuring the thermal stress peak value was as described above. The thermal stress peak value retention rate was then calculated using the following formula.

[0051]

number

[0052] Here, RB is the retention rate of the thermal stress peak value, VB1 is the thermal stress peak value of the inelastic yarn taken out from the grey fabric (value per dtex), and VB2 is the thermal stress peak value of the inelastic yarn taken out from the double knit fabric as a finished product (value per dtex).

[0053] (3) Breaking strength retention rate Inelastic yarns were taken from the grey fabric and the double knit fabrics as finished products that had been heat-treated at each temperature, and the breaking strength of each inelastic yarn was measured five times to calculate the average value. The breaking strength measurement method was as described above. The breaking strength retention rate was then calculated using the following formula.

[0054]

number

[0055] Here, RC is the breaking strength retention rate, VC1 is the average breaking strength of non-elastic yarns taken out from the grey fabric, and VC2 is the average breaking strength of non-elastic yarns taken out from the double knit fabric as a finished product.

[0056] (4) Elastic modulus retention rate Inelastic yarns were taken from the grey fabric and the double knit fabrics as finished products that had been heat-treated at each temperature, and the modulus of elasticity of each inelastic yarn was measured five times to calculate the average value. The modulus of elasticity was measured as described above. The retention rate of the modulus of elasticity was calculated using the following formula:

[0057]

number

[0058] Here, RD is the elastic modulus maintenance rate, VD1 is the average value of the elastic modulus of the non-elastic yarn taken out from the grey fabric, and VD2 is the average value of the elastic modulus of the non-elastic yarn taken out from the double knit fabric as a finished product.

[0059] (5) Results The results for each retention rate are shown in Table 2.

[0060] In addition, garments were manufactured using knitted fabrics 1 to 3 in Table 2, and the wearing comfort (tightness) when worn and the presence or absence of fraying or curling from the raw edge of the garment were checked. They were then evaluated with ○ (good), △ (slightly poor), and × (poor). The results are shown in Table 2.

[0061] [Table 2]

[0062] For reference, a peel strength test was conducted at the contact points between polyurethane elastic yarns. The test was conducted in accordance with JIS L 1085. Specifically, 22 dtex bare spandex was prepared as the polyurethane elastic yarn, and two yarn bundles were prepared by winding multiple polyurethane elastic yarns five times. The two yarn bundles were then entangled. A load of 0.25 g was then applied in the extension direction of the yarn bundles, stretching the two entangled yarn bundles 100% and placing them on a predetermined frame. The yarn bundles in this state were heat-treated at a predetermined temperature for 90 seconds to bond the polyurethane elastic yarns together. The heat treatment temperatures were three levels: 185°C, 195°C, and 205°C. After heat treatment, the polyurethane elastic yarns constituting the yarn bundles were pulled in the peel direction to measure the peel strength. The peel strength was measured five times for each temperature level, and the average value was calculated.

[0063] The results are shown in Table 3, and it was confirmed that the peel strength was particularly high when the heat treatment temperature was 195°C.

[0064] [Table 3] [Explanation of symbols]

[0065] 1...Non-elastic yarn, 2...Polyurethane elastic yarn

Claims

1. A method for producing a double knit fabric containing a non-elastic yarn and a polyurethane elastic yarn, A grey fabric containing the non-elastic yarn and the polyurethane elastic yarn is knitted, By heat-treating the grey machine, the peak value of the thermal stress for the inelastic yarn taken out from the double knit fabric after the grey machine has been heat-treated is set to 30% or more and 40% or less of the peak value of the thermal stress for the inelastic yarn taken out from the grey machine before the heat-treatment, The heat treatment includes a heat set and a final set that is performed after the heat set, The final set is performed at a temperature of 130° C. or higher and 170° C. or lower for a treatment time of 50 seconds or higher and 70 seconds or lower, In the double knit fabric after the heat treatment, the product of warp density and weft density is 4000 / square inch or more, the cover factor of the inelastic yarn is 7 or more and 15 or less, and the cover factor of the polyurethane elastic yarn is 2 or more and 5 or less. A method for manufacturing double knit fabric.

2. A method for manufacturing a double knit fabric as described in claim 1, wherein the heat treatment makes the breaking strength of the non-elastic yarn removed from the double knit fabric after the green machine has been heat-treated 70% or more of the breaking strength of the non-elastic yarn removed from the double knit fabric when the green machine is in the green state.

3. The method for producing a double knit fabric according to claim 1 or 2, wherein the peel strength between the polyurethane elastic yarns in the double knit fabric after the heat treatment is 7 cN or more.

4. A method for manufacturing a double knit fabric as described in claim 1 or 2, wherein by performing the heat treatment, the elastic modulus of the inelastic yarn extracted from the double knit fabric after the grey fabric has been heat-treated is 50% or more and 70% or less of the elastic modulus of the inelastic yarn extracted from the double knit fabric when the fabric is still in its green state.

Images