Method for manufacturing a knitted fabric comprising plant-derived ptt-based yarn

Abstract

A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn comprises, in a method for manufacturing a knitted fabric made of 100% plant-derived PTT-based yarn, a knitting step in which the PTT-based yarn is knitted into an interlock structure forming a left-right symmetrical double loop structure using a circular knitting machine to form a double loop structure including a plurality of loops, and a tenter step in which the knitted fabric is supplied to a tenter device and a heat setting process is performed on the knitted fabric in the tenter device to stabilize the double loop structure, thereby improving the burst strength and elastic recovery characteristics of the fabric, wherein, during knitting, the gauge of the circular knitting machine, the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric are set considering the target burst strength of the fabric.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, and more specifically, to a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn by knitting the plant-derived PTT-based yarn in an interlock structure to form a double loop structure, and stabilizing the formed double loop structure through a heat setting process using a tenter to provide excellent burst strength, elastic recovery characteristics, and dimensional stability. Background Technology

[0002] With the recent increase in demand for eco-friendly fibers, the development of synthetic fibers using plant-derived raw materials is actively underway.

[0003] Representative plant-derived PTT (Polytrimethylene Terephthalate) yarns can be manufactured using bio-based raw materials and have the advantage of providing excellent elasticity, elastic recovery characteristics, and tactile feel (refer to Patent Application No. 10-2017-0124817).

[0004] For example, DuPont's Sorona fiber can be used as a PTT-based yarn.

[0005] In addition, since PTT-based yarns can exhibit excellent elastic recovery even without using spandex, they are being applied in various fields such as eco-friendly clothing, sportswear, and athleisure wear.

[0006] However, the loop structure of these PTT-based yarns can easily change depending on heat and tension conditions, and if the heat setting conditions performed after knitting are not appropriate, problems such as an uneven loop structure, insufficient burst strength, or reduced elastic recovery characteristics after repeated stretching may occur. The problem to be solved

[0007] To address these problems, there is a growing need for a method to manufacture knitted fabrics made of plant-derived PTT-based yarns that can simultaneously secure high burst strength and excellent dimensional stability while maintaining the excellent elastic properties of plant-derived PTT-based yarns.

[0008] The problem that the present invention aims to solve is to provide a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein the plant-derived PTT-based yarn is knitted in an interlock structure to form a double loop structure, and the formed double loop structure is stabilized through a heat setting process using a tenter to have excellent burst strength, elastic recovery characteristics, and dimensional stability.

[0009] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0010] A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to an embodiment of the present invention for solving the above problem comprises: a knitting step of forming a double loop structure including a plurality of loops by knitting the PTT-based yarn into an interlock structure that forms a left-right symmetric double loop structure using a circular knitting machine; and a tenter step of improving the burst strength and elastic recovery characteristics of the fabric by supplying the knitted fabric to a tenter device and performing a heat setting process on the knitted fabric in the tenter device to stabilize the double loop structure. During knitting, the gauge of the circular knitting machine, the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric are set considering the target burst strength of the fabric. Effects of the invention

[0011] According to the present invention, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn can be provided, wherein the plant-derived PTT-based yarn is knitted in an interlock structure to form a double loop structure, and the formed double loop structure is stabilized through a heat setting process using a tenter to have excellent burst strength, elastic recovery characteristics, and dimensional stability. Brief explanation of the drawing

[0012] FIG. 1 is a flowchart of a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to one embodiment of the present invention. Figure 2 is a diagram showing the operation sequence of various equipment used in the method of manufacturing knitted fabric. Figure 3 is a diagram comparing the heat setting temperature, fabric transfer speed, tension applied to the fabric, and fabric width in the first heat setting process and the second heat setting process. Figure 4 is a drawing showing a pair of guide rails constituting a tenter device including a straight section and an arc section. Figure 5 is a diagram showing the process of a control unit controlling the operation of a cooling device using feedback information of the fabric temperature measured by a temperature sensor. Specific details for implementing the invention

[0013] The present invention is not limited to the embodiments disclosed below but may be implemented in various different forms, and these embodiments are provided merely to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention.

[0014] In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used in this specification, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, and actions in addition to the mentioned components, steps, and actions.

[0015] With reference to FIGS. 1 and 2, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to one embodiment of the present invention will be described.

[0016] FIG. 1 is a flowchart of a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to one embodiment of the present invention. FIG. 2 is a diagram showing the operation sequence of various equipment used in the method for manufacturing a knitted fabric.

[0017] Referring to FIGS. 1 and 2, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to one embodiment of the present invention may include a yarn supply step (S10), a knitting step (S20), a tenter step (S30), a cooling step (S40), and a winding step (S50).

[0018] The yarn supply step (S10) is a step in which plant-derived PTT-based yarn can be supplied to a circular knitting machine (10), and the yarn is supplied under a constant tension state.

[0019] PTT-based yarn may refer to PTT (Polytrimethylene Terephthalate)-based fibers containing 1,3-propanediol (1,3-Propanediol) or Polytrimethylene Terephthalate (PTT)-based fibers manufactured using plant-derived raw materials such as corn.

[0020] In the present invention, 100% plant-derived PTT-based yarn can be used instead of spandex.

[0021] In this regard, spandex is generally often blended to improve the elasticity of knitted fabrics. However, when spandex is blended with other fibers, recycling the fabric may not be easy, and the material separation process may become complex.

[0022] In addition, as the demand for eco-friendly materials increases, there is a growing need for materials that can reduce or replace the use of spandex.

[0023] Considering these points, the present invention can secure sufficient elasticity through the excellent elastic recovery characteristics of PTT-based yarn and the double loop structure of the interlock structure described below, even without using separate spandex.

[0024] In addition, by not using spandex, the decrease in elasticity due to repeated stretching can be reduced, and excellent physical property stability can be secured even during the heat setting process.

[0025] Furthermore, since single-material-based fabrics can be manufactured, recyclability is improved, and they can be utilized as eco-friendly fabrics.

[0026] The knitting step (S20) is a step of forming a double loop structure including multiple loops by knitting PTT-based yarn into an interlock structure that forms a left-right symmetrical double loop structure using a circular knitting machine (10).

[0027] Here, the interlock structure refers to a double knitting structure formed in two needle beds and may include a double loop structure in which the front and back sides of the fabric (5) are symmetrically formed.

[0028] The circular knitting machine (10) may include an upper needle bed, a lower needle bed, a yarn feeding device, a tension control unit, and a control unit (50).

[0029] The upper needle bed and the lower needle bed can cooperate with each other to form an interlock structure.

[0030] Specifically, the upper needle bed can form a first loop and the lower needle bed can form a second loop, and the first loop and the second loop intersect each other to form a left-right symmetric double loop structure.

[0031] The double loop structure formed in this way may be a structure in which a plurality of first loops and a plurality of second loops interlock with each other.

[0032] Accordingly, the thickness of the fabric (5) is increased, the bonding strength between the loops is improved, and the burst strength can be increased.

[0033] In addition, the double loop structure ensures excellent appearance quality because both sides of the fabric (5) are formed with almost the same texture.

[0034] In the present invention, when knitting, the gauge (G) of the circular knitting machine (10), the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric (5) can be set by taking into account the target burst strength of the fabric (5).

[0035] Meanwhile, the gauge of the circular knitting machine (10) refers to the number of needles arranged within a certain length (usually 1 inch).

[0036] In particular, in the present invention, the gauge of the circular knitting machine (10), the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric (5) can be set in conjunction with each other based on the target burst strength.

[0037] For example, as the target burst strength increases, the gauge can be increased or the loop length can be decreased to increase the loop density.

[0038] Conversely, if you want to further improve the elasticity of the fabric (5), you can increase the loop length and adjust the loop density.

[0039] Therefore, each knitting condition is not an independent variable but can be determined in conjunction with others as a design variable to satisfy the target physical properties.

[0040] Below, we will examine each of the knitting conditions mentioned above in detail.

[0041] First, in the present invention, the gauge (G) of the circular knitting machine (10) may be 38 to 42G.

[0042] If the gauge is less than 38G, the number of loops per unit area decreases, which may reduce the burst strength.

[0043] Conversely, if the gauge exceeds 42G, knitting performance may be reduced or excessive stress may be applied to the yarn.

[0044] Accordingly, the present invention can simultaneously secure loop density and knitting stability by setting the gauge of the circular knitting machine (10) to a range of 38 to 42G.

[0045] In the present invention, the feeding tension of the yarn supplied to the circular knitting machine (10) may be 18 to 27 cN.

[0046] If the feeding tension is less than 18 cN, the loop may become excessively large and the uniformity of the loop shape may be reduced.

[0047] Conversely, if the feeding tension exceeds 27 cN, the loop may be tightened excessively, and the elasticity of the fabric (5) may be reduced.

[0048] Accordingly, the present invention can stably form a loop shape by setting the feeding tension to a range of 18 to 27 cN.

[0049] In the present invention, the loop length can be set by considering the gauge of the circular knitting machine (10), the feeding tension, the thickness of the yarn, the loop density, the target weight per unit area, etc.

[0050] Accordingly, the bonding strength between loops is improved, and the knitting structure can be formed uniformly.

[0051] In the present invention, the loop density can be set in the horizontal direction and the vertical direction, respectively.

[0052] Loop density refers to the number of loops formed per unit length of the knitted fabric and may include both course density and wave density.

[0053] The horizontal loop density may be 50 to 60 / inch, and the vertical loop density may be 55 to 65 / inch.

[0054] By setting the loop density in this way, the loop structure can be formed uniformly, and the burst strength of the fabric (5) can be improved by securing a sufficient number of loops per unit area.

[0055] In addition, the elastic recovery properties of the fabric (5) can be maintained by preventing the loop from becoming excessively dense.

[0056] In the present invention, the weight per unit area of ​​the fabric may be 260 to 280 gsm (g / ㎡).

[0057] This range may be a resulting value formed by knitting conditions and loop density, or conversely, it may be set as a design target value to satisfy the target burst strength.

[0058] That is, the gauge, feeding tension, loop length, and loop density of the circular knitting machine (10) can be set in conjunction so that the weight per unit area of ​​the fabric (5) is 260 to 280 gsm.

[0059] In the present invention, the target burst strength of the fabric (5) may be 400 to 550 N.

[0060] As described above, the target burst strength can be determined by correlating the gauge of the circular knitting machine (10), the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric (5).

[0061] That is, in the present invention, instead of individually optimizing specific knitting conditions, the entire knitting condition is designed based on the target burst strength, thereby simultaneously securing the strength and elastic recovery characteristics of the fabric (5).

[0062] In addition, the subsequent tenter process can be performed to stabilize the loop structure while maintaining the target burst strength, thereby further improving the dimensional stability and shape stability of the fabric (5) after washing.

[0063] Meanwhile, if the target burst strength is less than 400N, the likelihood of loop breakage or tissue deformation occurring during repeated wear or washing of the clothing may increase.

[0064] On the other hand, if the design is made to exceed a target burst strength of 550N, the loop density and fabric weight increase excessively, which may reduce the flexibility and comfort of the fabric.

[0065] Therefore, in the present invention, by setting the burst strength to a range of 400 to 550 N, a balance of durability, elastic recovery characteristics, and wearing comfort can be simultaneously secured.

[0066] The tenter step (S30) is a step of improving the burst strength and elastic recovery characteristics of the fabric (5) by supplying the knitted fabric (5) to the tenter device (20) and performing a heat setting process on the knitted fabric (5) in the tenter device (20) to stabilize the double loop structure.

[0067] The tenter device (20) may include a fabric supply unit, a clip chain (27) or a pin chain, a heat setting unit, and a control unit (50).

[0068] The fabric supply unit can supply the fabric (5) manufactured in the knitting process to the tenter device (20).

[0069] A clip chain (27) or pin chain can grip both edges of the fabric to maintain the width of the fabric while transporting the fabric (5).

[0070] The heat setting unit can heat the fabric (5) to a preset temperature to stabilize the loop structure.

[0071] The control unit (50) can control the tenter temperature, fabric width, transfer speed, dwell time, and tension.

[0072] In the present invention, tenter conditions such as tenter temperature, fabric width, fabric feed speed, residence time, and fabric tension can be determined in conjunction to stably maintain the loop structure formed during the knitting stage while securing target burst strength and elastic recovery characteristics.

[0073] For example, if the tenter temperature increases, the transfer speed can be increased or the residence time reduced to prevent excessive thermal deformation of the PTT-based yarn.

[0074] Conversely, when reducing the transfer speed, the tenter temperature can be set slightly lower to suppress excessive shrinkage of the loop structure.

[0075] In addition, increasing the fabric width can reduce tension to prevent excessive elongation of the loop, and increasing the tension can adjust the fabric width to minimize shrinkage in the width direction.

[0076] In this way, by controlling each tenter condition in conjunction with one another, the loop structure can be uniformly stabilized.

[0077] Below, we will examine each of the tenter conditions mentioned above in detail.

[0078] First, in the present invention, the tenter temperature may be 175 to 195°C.

[0079] If the tenter temperature is below 175℃, the residual stress inside the loop may not be sufficiently relieved, and the loop shape may remain unstable.

[0080] Conversely, if the temperature exceeds 195℃, there is a risk that the elastic properties of the PTT-based yarn may deteriorate.

[0081] Accordingly, the present invention can stably fix the loop structure while maintaining elastic recovery characteristics by setting the tenter temperature to a range of 175 to 195°C.

[0082] In the present invention, the fabric width may be 53 to 55 inches.

[0083] If the fabric width is less than 53 inches, shrinkage in the width direction may increase, and conversely, if it exceeds 55 inches, the loop may be excessively stretched and the loop shape may be deformed.

[0084] Accordingly, the present invention can ensure dimensional stability in the width direction by setting the fabric width to a range of 53 to 55 inches.

[0085] In the present invention, the fabric conveying speed may be 40 to 50 m / min.

[0086] If the fabric transfer speed is less than 40 m / min, the residence time may increase excessively and overheating may occur, whereas if it exceeds 50 m / min, heat setting may not be sufficiently achieved.

[0087] Accordingly, the present invention enables uniform heat setting by setting the fabric transfer speed to a range of 40 to 50 m / min.

[0088] In the present invention, the dwell time of the fabric (5) may be 35 to 45 seconds.

[0089] If the residence time is less than 35 seconds, the loop structure may not be sufficiently stabilized, whereas if it exceeds 45 seconds, excessive thermal history of the yarn may occur.

[0090] Accordingly, the present invention can ensure that the loop structure is sufficiently stabilized by setting the residence time to a range of 35 to 45 seconds.

[0091] In the present invention, the fabric tension may be 20 to 30 N.

[0092] If the fabric tension is less than 20N, the loops may not be sufficiently aligned, whereas if it exceeds 30N, the loops may be excessively stretched.

[0093] Accordingly, the present invention can ensure uniformity of the loop shape by setting the fabric tension to a range of 20 to 30 N.

[0094] In the present invention, the above tenter conditions can be set to maintain a target burst strength of 400 to 550 N by being correlated with the gauge, feeding tension, loop length, loop density, and weight per unit area of ​​the fabric (5) set during the knitting stage.

[0095] In other words, the tenter process may be a process that, rather than a process of forming new strength, stably fixes the loop structure formed during the knitting stage so that the target burst strength secured during the knitting stage is maintained even after processing.

[0096] Accordingly, the present invention can stably secure a burst strength of 400 to 550 N while maintaining the excellent elastic recovery characteristics of PTT-based yarns.

[0097] The cooling step (S40) is a step of cooling the fabric (5) that has completed heat setting through the cooling equipment (30) to stably fix the loop structure of the fabric (5).

[0098] The cooling equipment (30) may include a blower fan, a cold air supply device, a cooling duct, or a combination thereof, and may cool the fabric (5) by supplying cooling air to both sides of the fabric (5).

[0099] The fabric (5) can be transported with its width maintained by the tenter chain even during the cooling process, and accordingly, the loop structure and dimensional stability formed during the heat setting process can be maintained.

[0100] The winding step (S50) is a step of winding the cooled fabric into a roll shape using a winding device (40).

[0101] The winding equipment (40) may include a winding roller, a drive motor, and a winding tension control unit (50).

[0102] The winding roller winds the fabric (5) after cooling is complete, and the drive motor can control the winding speed. The winding tension control unit (50) can control the winding tension applied to the fabric (5) during the winding process so that the fabric (5) is wound at a constant tension state.

[0103] In the present invention, the winding speed can be controlled to be linked with the fabric transfer speed of the tenter device (20).

[0104] Accordingly, it is possible to prevent excessive tension from being applied to the fabric (5) or the fabric (5) from being wound loosely.

[0105] In addition, the winding tension can be set within a range where the loop structure of the fabric (5) is not deformed.

[0106] In other words, if the winding tension increases excessively, the loop structure stabilized through the heat setting and cooling processes may stretch again, potentially changing the fabric width or loop density; therefore, it is desirable to control the winding tension within a range that maintains the shape of the loop structure.

[0107] In this embodiment, the fabric (5) that has been wound may be supplied directly to a subsequent cutting or sewing process without a separate aging process, or it may be supplied to a subsequent process after being stored for a certain period of time as needed.

[0108] The above describes a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to one embodiment of the present invention. Hereinafter, with reference to FIG. 3, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention will be described.

[0109] Figure 3 is a diagram comparing the heat setting temperature, fabric transfer speed, tension applied to the fabric, and fabric width in the first heat setting process and the second heat setting process.

[0110] Referring to FIG. 3, in a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention, the tenter step may be performed as a plurality of heat setting processes including a first heat setting process and a second heat setting process.

[0111] While heat setting of general knitted fabrics is often performed in a single temperature range, the present invention can form a loop structure more stably by performing heat setting in multiple stages with different purposes.

[0112] Specifically, the first heat setting process is a process for relieving residual stress inside the double loop structure formed during the knitting process.

[0113] Immediately after knitting, internal stress exists to maintain the yarn in a bent loop shape, and localized stress concentration may occur between the loops.

[0114] Therefore, in the first heat setting process, the internal stress of the yarn can be gradually relieved by heating the yarn at a relatively low temperature.

[0115] In one embodiment, the first heat setting process may be performed at a first heat setting temperature (Temp1) of 155 to 165°C.

[0116] Below 155℃, the effect of relieving residual stress may not be sufficient, and if it exceeds 165℃, the loop shape stabilization effect that must be secured in the subsequent second heat setting process may be reduced.

[0117] In addition, a relatively high first transfer speed (V1) can be applied in the first heat setting process.

[0118] In this way, by conveying the fabric (5) at a relatively high first conveying speed (V1), the fabric can be prevented from being excessively exposed to high temperatures while also relieving residual stress inside the yarn.

[0119] Accordingly, it is possible to induce a more stable state of the loop structure while suppressing excessive deformation of the loop shape.

[0120] The second heat setting process is performed after the first heat setting process and is a process that finally stabilizes the loop structure with relieved residual stress.

[0121] In the second heat setting process, the loop shape can be stably fixed at the second heat setting temperature (Temp2), which is a higher temperature than the first heat setting process.

[0122] In one embodiment, the second heat setting process can be performed at 175 to 185°C.

[0123] In addition, the second heat setting process can be performed at a second transfer speed (V2) that is slower than the first transfer speed (V1) of the first heat setting process.

[0124] By reducing the transfer speed, the loop structure is sufficiently exposed to high temperatures, allowing the loop shape to be fixed more uniformly.

[0125] As a result, after the second heat setting process, the double loop structure is stably maintained, so the dimensional stability of the fabric (5) and shape stability after washing can be improved.

[0126] Additionally, in the first heat setting process, a first tension (Tens1) can be applied, and the first tension (Tens1) performs the role of making the loop arrangement uniform while maintaining the basic shape of the fabric (5) in the width and length directions.

[0127] In addition, in the second heat setting process, a second tension (Tens2) smaller than the first tension (Tens1) may be applied. Accordingly, the loop shape can be naturally fixed and stabilized while preventing the loop from being excessively stretched.

[0128] That is, the tension applied to the fabric (5) during the tenter process can be changed step by step.

[0129] If the first tension (Tens1) is maintained until the second heat setting process, there is a risk that the loop will be excessively tensioned and the loop shape will be deformed.

[0130] On the other hand, if the tension is reduced to the second tension (Tens2) in the second heat setting process, the shape can be fixed without the loop being excessively stretched.

[0131] Therefore, the uniformity of the loop structure is improved, and the variation in burst strength across the entire fabric can be reduced.

[0132] In addition, the tension may be reduced in steps or controlled to decrease continuously.

[0133] Meanwhile, the control unit (50) can automatically control the fabric tension by controlling the driving force of the tension control roller or clip chain (27) based on the measurement value of the tension sensor.

[0134] Additionally, as the process proceeds from the first heat setting process to the second heat setting process, the width of the fabric (5) can be increased step by step.

[0135] In the first heat setting process, in order to relieve the stress remaining in the loop structure immediately after knitting, the width (W1) of the fabric (5) can be maintained in a state that is substantially the same as or close to the width immediately after knitting.

[0136] Afterwards, in the second heat setting process, the loop structure can be rearranged in the width direction while gradually increasing the width of the fabric (5) to the target width (W2).

[0137] In this process, stress concentration between loops can be reduced and the uniformity of loop density can be improved, and the rearranged loop structure can be stably fixed during the subsequent cooling stage.

[0138] In addition, such changes in fabric width can be performed in conjunction with changes in tension.

[0139] In other words, by reducing tension in the section where the width is increased and maintaining constant tension in the section where the target width is reached, the loop structure can be stabilized more uniformly.

[0140] The above describes a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention. Hereinafter, with reference to FIG. 4, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to yet another embodiment of the present invention will be described.

[0141] Figure 4 is a drawing showing a pair of guide rails constituting a tenter device including a straight section and an arc section.

[0142] Referring to FIG. 4, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention can apply repetitive tension and relaxation to the knitted fabric (5) in the width direction of the fabric during the tenter process.

[0143] To this end, the tenter device (20) may include a pair of clip chains (27) that support each of the two edges of the knitted fabric (5) with respect to the width direction, and a pair of guide rails (25) that guide each of the pair of clip chains (27).

[0144] A pair of guide rails (25) are formed such that the spacing between them repeatedly increases and decreases along the direction of travel of the fabric, thereby allowing for repeated tension and relaxation in the width direction to be applied to the knitted fabric (5) moving along the clip chain (27).

[0145] This repeated tensioning and relaxation can finely rearrange the double loop structure in the width direction that is not completely fixed during heat setting and relieve local stress remaining in the loop structure. Accordingly, the variation in loop density in the width direction and the variation in shrinkage of the fabric (5) are reduced, and the dimensional stability and uniformity of physical properties of the fabric (5) can be improved.

[0146] In one embodiment, a pair of guide rails (25) include a straight section in which no tension or relaxation occurs and an arc section in which tension and relaxation occur gradually, and the straight section and the arc section may be formed alternately.

[0147] Due to this structure, the width of the fabric (5) changes gradually in the arc section, so it is possible to prevent sudden changes in tension in the fabric (5).

[0148] In addition, local stress concentrations can be relieved as the loop structure is gradually rearranged.

[0149] Subsequently, since a constant width is maintained in the straight section, the rearranged loop structure can be stabilized, and the uniformity of loop density can be improved.

[0150] Accordingly, the uniformity of the dimensional stability, burst strength, and elastic recovery characteristics of the fabric (5) can be improved.

[0151] Additionally, the maximum spacing between a pair of guide rails (25) in the arc section can be formed to increase by 0.5 to 3% compared to the minimum spacing.

[0152] At this time, the minimum gap may be the entry point of a pair of guide rails (25).

[0153] If the increase is less than 0.5%, the repetitive tension and relaxation in the width direction applied to the fabric is insufficient, so the rearrangement effect of the loop structure may be minimal.

[0154] On the other hand, if the increase exceeds 3%, the fabric may be excessively stretched in the width direction, causing the loop shape to deform, the variation in loop density to increase, and the burst strength and dimensional stability to decrease.

[0155] Accordingly, by forming the maximum spacing between a pair of guide rails (25) in the arc section to increase by 0.5 to 3% compared to the minimum spacing, appropriate repetitive tension and relaxation in the width direction can be applied to the fabric during heat setting.

[0156] Accordingly, the loop structure is gradually rearranged, residual stress in the loop can be relieved, and the uniformity of the loop density can be improved.

[0157] In addition, the rearranged loop structure can be stabilized while maintaining a constant width in the subsequent straight section, and can be finally fixed during the cooling stage.

[0158] As a result, the dimensional stability, elastic recovery, and target burst strength of the fabric can be secured more reliably.

[0159] The above describes a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention. Hereinafter, with reference to FIG. 5, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention will be described.

[0160] Figure 5 is a diagram showing the process of a control unit controlling the operation of a cooling device using feedback information of the fabric temperature measured by a temperature sensor.

[0161] Referring to FIG. 5, a method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to another embodiment of the present invention can control the operation of the cooling equipment (30) so that the temperature of the fabric (5) follows a preset cooling profile when cooling the fabric (5) that has been heat-set by the cooling equipment (30) in the cooling stage after the tendering stage.

[0162] The cooling equipment (30) may include a blower, a cold air supply, or a combination thereof, and can supply cooling air to the fabric (5) to stably fix the loop structure.

[0163] In particular, in the present invention, cooling is not simply performed, but the cooling speed of the fabric (5) is controlled so that the temperature of the fabric (5) follows a preset cooling profile.

[0164] To this end, the control unit (50) can receive a measurement value from a non-contact temperature sensor (60), such as an infrared temperature sensor, that measures the surface temperature of the fabric (5).

[0165] The non-contact temperature sensor (60) can measure the surface temperature of the fabric (5) being cooled in real time without contacting the fabric (5).

[0166] Accordingly, mechanical contact force can be prevented from acting on the loop structure immediately after heat setting, which has not yet been fully stabilized, and the actual surface temperature of the fabric (5) can be accurately detected without deformation of the loop structure.

[0167] Additionally, since the non-contact temperature sensor (60) can measure the surface temperature of the continuously moving fabric (5) in real time, the cooling equipment (30) can adjust at least one of the cooling air volume, the temperature of the cooling air, or the cooling time according to the measured surface temperature of the fabric (5).

[0168] Accordingly, the actual cooling rate of the fabric (5) can be maintained close to the preset cooling profile, and the stabilization of the loop structure, reduction of residual stress, and uniform securing of the target burst strength are possible.

[0169] The fabric (5) can be controlled to be gradually cooled by adjusting the flow rate, airflow, or temperature of the cooling air according to the temperature measured by the non-contact temperature sensor (60).

[0170] In this way, controlling the cooling rate can prevent the loop structure from shrinking rapidly immediately after heat setting.

[0171] In addition, the loop shape is stabilized stepwise, which can reduce variations in loop density and improve dimensional stability.

[0172] Although embodiments of the present invention have been described above, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. Explanation of the symbols

[0173] 5: Fabric 10: Circular knitting machine 20: Tenter device 25: Guide rail 27: Clip chain 30: Cooling equipment 40: Winding equipment 50: Control unit 60: Temperature sensor

Claims

Claim 1 A method for manufacturing a knitted fabric made of 100% plant-derived PTT (Polytrimethylene Terephthalate) yarn, comprising: a knitting step of forming a double loop structure including a plurality of loops by knitting the PTT yarn using a circular knitting machine to form an interlock structure that forms a left-right symmetric double loop structure; and a tenter step of supplying the knitted fabric to a tenter device and performing a heat setting process on the knitted fabric in the tenter device to stabilize the double loop structure, thereby improving the burst strength and elastic recovery characteristics of the fabric, wherein, during knitting, the gauge of the circular knitting machine, the feeding tension of the yarn, the loop length, the loop density, and the weight per unit area of ​​the fabric are set considering the target burst strength of the fabric. Claim 2 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to claim 1, wherein the gauge is 38 to 42G, the feeding tension is 18 to 27cN, the weight per unit area of ​​the fabric is 260 to 280gsm, the transverse loop density of the fabric is 50 to 60 / inch, the longitudinal loop density is 55 to 65 / inch, and the target burst strength is 400 to 550 N or less. Claim 3 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to claim 2, wherein the tenter device performs heat setting while maintaining the width-direction dimensions of the knitted fabric after setting the tenter temperature, fabric width, fabric feed speed, residence time, and fabric tension, wherein the tenter temperature is 175 to 195℃, the fabric width is 53 to 55 inches, the fabric feed speed is 40 to 50 m / min, the residence time is 35 to 45 seconds, and the fabric tension is 20 to 30 N. Claim 4 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to claim 1, wherein the heat setting process comprises a first heat setting process and a second heat setting process, wherein the first heat setting process is performed at a temperature of 155 to 165°C and a first transfer speed to relieve residual stress of the double loop structure formed during the knitting process, and the second heat setting process is performed at a temperature of 175 to 185°C and a second transfer speed slower than the first transfer speed to stabilize the double loop structure and improve the dimensional stability of the fabric. Claim 5 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein, in claim 4, a first tension is applied in the first heat setting process and a second tension smaller than the first tension is applied in the second heat setting process. Claim 6 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn according to claim 4, wherein in the first heat setting process, the width of the fabric is maintained to be the same as the width immediately after knitting to relieve residual stress in the loop structure, and in the second heat setting process, the width of the fabric is gradually increased to a target width while stabilizing the loop structure. Claim 7 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein, in claim 1, the tenter device comprises: a pair of clip chains each supporting both edges of the knitted fabric in the width direction; and a pair of guide rails each guiding the pair of clip chains, wherein the pair of guide rails are formed such that the spacing between them repeatedly increases and decreases along the direction of travel of the fabric, thereby imparting repeated tension and relaxation in the width direction to the knitted fabric moving along the clip chains. Claim 8 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein, in claim 7, the pair of guide rails comprises a straight section in which tension and relaxation do not occur; and an arc section in which tension and relaxation occur gradually, and the straight section and the arc section are formed alternately. Claim 9 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein, in claim 8, the maximum spacing between the pair of guide rails in the arc section is formed to increase by 0.5 to 3% compared to the minimum spacing. Claim 10 A method for manufacturing a knitted fabric made of plant-derived PTT-based yarn, wherein, in claim 1, when cooling the fabric with a cooling device after the tenter step, the surface temperature of the fabric is measured through a non-contact temperature sensor, and the operation of the cooling device is controlled according to the measured temperature so that the temperature of the fabric follows a preset cooling profile.

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