Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B21/00—Warp knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
  • D04B21/14—Fabrics characterised by the incorporation by knitting, in one or more thread, fleece, or fabric layers, of reinforcing, binding, or decorative threads; Fabrics incorporating small auxiliary elements, e.g. for decorative purposes
  • D04B21/18—Fabrics characterised by the incorporation by knitting, in one or more thread, fleece, or fabric layers, of reinforcing, binding, or decorative threads; Fabrics incorporating small auxiliary elements, e.g. for decorative purposes incorporating elastic threads
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2501/00—Wearing apparel
  • D10B2501/02—Underwear

Definitions

• the stretchable fabrics are required to have comfortable stretch and compression, good hand feel, as well as having high durability.
• Many of the stretchable fabrics contain elastic yarns, predominately spandex yarns which are warp-knitted with other hard yarns such as nylon or polyethylene terephthalate to provide the desired hand feel and durability.
• Warp knit fabrics are well known materials. They can be conventionally produced on Ketten, Raschel or tricot knitting machines. Processes and apparatus for preparing warp knit fabrics are disclosed, for example, in U.S. Pat. Nos. 4,487,040 and 4,802,346 and in PCT Patent Application No. WO 03/023105. All of these patent documents are incorporated herein by reference.
• Korean Patent Application No. 2002-0001924 discloses a method of manufacturing a warp knit fabric containing 70-95 weight% of 50-70d polytrimethylene terephthalate (PTT) multifilament fibers and 5-30 weight% of 20-70d spandex fibers on a 2 guide bar tricot machine of 28 gauge.
• the resulting fabric has a basis weight ranging from 80-170 g/m 2 .
• Japanese Patent Application No. 11-81096 discloses knit fabrics made by Raschel or tricot knitting machines, which comprises PTT fibers and elastic fibers, wherein the content of the elastic fibers is 5 to 30 weight%, elastic draft of 1.5 times-3.5 times, and the fineness ratio of elastic fibers to PTT fibers is 0.1-15, preferably 0.5-9.
• a tricot knitting machine of 28 gauge was used to make a soft fabric of unspecified pattern containing 50d/36f PTT fibers and 40d polyurethane fibers, where the run-in of the front bar is 160 cm/480 courses (i.e. 1 rack) and the run-in of the back bar is 80 cm/480 courses.
• a first aspect of the invention includes a warp knit fabric having a locknit pattern comprising:
• polytrimethylene terephthalate (PTT) yarn having a total fineness in the range of 30-75 deniers
• warp knit fabric having a locknit pattern comprises:
• run-in length of the PTT yarns ranges from 1400-2000
• run-in length of the elastic yarns ranges from 200-1000
• FIG. 1 is a schematic diagram of a beam for either PTT yarns or elastic yarns.
• FIG. 2 is a schematic diagram of a portion of a tricot knitting machine with 2 guide bars for elastic yarns and PTT yarns.
• FIGs. 3A-3E are schematic diagrams of needle motion in a knitting process.
• FIGs. 4A-4B show the reverse side views of common warp knit fabrics patterns.
• the warp knit fabrics are constructed with the locknit pattern shown in FIG. 4B.
• FIG. 5 is a schematic diagram of the paths of a PTT yarn and its
• FIG. 6 is a flow chart showing the general finishing process steps after obtaining the greige fabrics of this invention.
• the term “produced from” is synonymous to “comprising”.
• the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof are intended to cover a non-exclusive inclusion.
• a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
• the phrase “consisting of appears in a clause of the body of a claim, rather than immediately following the preamble it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
• transitional phrase consisting essentially of is used to define a composition, method or apparatus that includes materials, steps, features, components, or elements, in addition to those literally discussed, provided that the additional materials, steps features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention.
• homopolymer refers to a polymer derived from polymerization of one species of monomer; "copolymer” refers to a polymer derived from polymerization of two or more species of monomers. Such copolymers include dipolymers, terpolymers or higher order copolymers.
• Embodiments of the present invention as described in the Summary of the Invention include any other embodiments described herein, can be combined in any manner.
• Fiber means a material in which the length to diameter ratio is greater than about 10. Fiber is typically classified according to its fineness. Fiber is generally defined as having a fiber fineness greater than about 15 denier, usually greater than about 30 denier. Fine denier fiber generally refers to a fiber having a fineness less than about 15 denier.
• elastic yarn as used herein will be understood to refer to a yarn made of a synthetic material (i.e. polymer or copolymers) that has the excellent stretchability and recovery such that the material is capable of repeated stretching to at least twice its original length (i.e. 100% elongation), as well as immediate and forcible recovery to its approximate original length upon release of stress.
• a synthetic material i.e. polymer or copolymers
• the term "draft” as used herein refers to the amount of stretch applied to a strand of elastic yarn, such as spandex, resulting in a reduction in fineness of the strand of elastic yarn.
• the draft of a fiber is directly related to the elongation (stretching) applied to the fiber. For example, 100% elongation corresponds to 2 times draft, and 200% elongation corresponds to 3 times draft, etc.
• Non-elastic yarn or “hard yarn” as used herein interchangeably means a fiber that is relatively not elastic as the “elastic yarn” defined above.
• the "hard yarn” is a continuous multifilament yarn, such as PTT, nylon, PET, rayon, acetate, or acrylic; although PTT is considerably more elastic in character than other listed hard yarns.
• warp direction refers to the length direction or the machine direction of the fabric
• weft direction refers to the width direction or the cross machine direction of the fabric
• total draft of elastic yarn as used herein will be understood to be a composite of key factors correlating to the performance of the warp knit fabric of locknit pattern. The calculation of total draft of elastic yarn is described in further detail herein below.
• the polytrimethylene terephthalate (PTT) yarns may be used in the warp knit fabrics having multiple filaments having a single intrinsic viscosity (IV), which differs from a composite fiber containing two kinds of PTT (i.e. having different IVs) as disclosed in US Patent No. 6,949,201.
• IV intrinsic viscosity
• Polytrimethylene terephthalate (PTT) resin is a polyester that may be prepared by the condensation polymerization of 1,3-propanediol and terephthalic acid. Alternatively, polytrimethylene terephthalate may also be prepared from 1,3-propanediol and dimethylterephthalate (DMT).
• DMT dimethylterephthalate
• the 1 ,3 -propanediol for use in making the PTT is preferably obtained biochemically from a renewable source ("biologically-derived" 1 ,3-propanediol).
• the PTT resin is preferably a homopolymer or a copolymer containing 90 mol % or more of repeating units of trimethylene terephthalate and 10 mol % or less of other ester units made from other diols and/or diacids.
• other diacids that are useful in copolymerization including aromatic dicarboxylic acids such as isophthalic acid, 5-sodium sulfonate isophthalate, phthalic acid, and 2,6-naphthalene dicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and 1,12-dodecanedioic acid.
• aromatic dicarboxylic acids such as isophthalic acid, 5-sodium sulfonate isophthalate, phthalic acid, and 2,6-naphthalene dicarboxylic acid
• aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and 1,12-dodecanedioic acid.
• diols examples include aliphatic diols such as ethylene glycol, 1 ,2- propanediol, 1 ,4-butanediol, neopentyl glycol, 1,6-hexanediol, and polyethylene glycol; and alicyclic diols such as 1 ,4-cyclohexane dimethanol. These diols and/or diacids may be used either singly or in the form of a mixture of two or more compounds.
• the most preferred PTT resin is a homopolymer.
• Intrinsic viscosity is a measure of the molecular weight of a polymer and may be measured according to ASTM D4603-96. Intrinsic viscosity typically increases with increasing polymer molecular weight, but is also dependent on the type of macromolecule, its shape or conformation, and the solvent it is measured in.
• the polytrimethylene terephthalate yarn is derived from PTT resin having an intrinsic viscosity ( ⁇ ) of about 0.8 to 1.2 dl/g, and preferably of about 0.9-1.1 dl/g.
• polytrimethylene terephthalates resin examples include without limitation SORONA ® from DuPont and CORTERRA ® from Shell Chemicals.
• the commercially available PTT resin in pellet form can be readily remelted and spun into filament yarn, or used directly in a spinning process by using a conventional apparatus known to one skilled in the art.
• Additives may be contained in the PTT resin pellets or added during the fiber spinning process.
• Such additives may include delusterants, for example, titanium oxide, heat stabilizers, antioxidants, antistatic agents, UV light absorbers, anti-fungal agents, or various pigments.
• the cross-sectional shape of a single PTT filament is not limited, and may be round, or in other shapes such as octalobal, delta, sunburst (also known as sol), scalloped oval, trilobal, tetra-channel (also known as quatra-channel), scalloped ribbon, ribbon, or starburst.
• the PTT filament may be solid, hollow or multi- hollow, but is preferably solid.
• a single PTT filament has a fineness of at least about 0.5 dpf (denier per filament), and up to about 5 or more dpf.
• Suitable PTT yarns are multifilament yarns that typically comprise at least 10 or more filaments, and preferably contain up to 80, more preferably up to 100 filaments. Yarns containing 10, 12, 24, 36, 48, 68 or 72 filaments are common.
• the PTT yarns typically have a total fineness of at least 30d, preferably at least 40d, and up to 60d, preferably up to 75d or more.
• the PTT yarn in the warp knit fabric, is a multi-filament yarn containing about 10-72 filaments and has a total fineness of about 30-75 deniers.
• the PTT yarns used to make the warp knit fabrics are yarns such as fully drawn yarn (FDY), partially oriented yarn (POY), spin annealed yarn (SAY), draw textured yarn (DTY) or air texture yarn (ATY).
• FDY fully drawn yarn
• POY partially oriented yarn
• SAY spin annealed yarn
• DTY draw textured yarn
• ATY air texture yarn
• the content of polytrimethylene terephthalate yarns employed in the warp knit fabric ranges from about 70 weight% to about 90 weight%, preferably from about 75 weight% to about 85 weight%, wherein the weight percentage is based on the total weight of the warp knit fabric.
• the elastic yarn used in the warp knit fabric is produced from synthetic material and has an elongation at break of 100% or greater, preferably, 200% or greater, and more preferably, 300% or greater.
• elastic yarn examples include without limitation spandex, elastane, anidex, elastoester, and combinations thereof.
• the elastic yarn is a spandex yarn.
• Spandex yarns comprising of at least 85% of a segmented polyurethane, can be formed from the polyurethane polymer solution through fiber spinning processes such as wet or dry spinning. In dry spinning, the polymer solution is metered through spinneret orifices into a spin chamber to form a filament or can be coalesced by conventional techniques into multi-filament yarns.
• the polyurethane polymer is dry spun into filament from the same solvent that is used for the polymerization reactions. Gas is passed through the chamber to evaporate the solvent to solidify the filament.
• spandex yarns include, for example, Lycra ® types T162B, T162C, T165C, T169B and T562, manufactured by INVISTA; ROCIA ® by Ashahi; CREORA® by Hyosung; and AOSHEN ® by Jiangsu Aoshen Group, Co., Ltd.
• the elastic yarns can also comprise conventional additives such as anti-tack agents, antioxidants, UV screeners, antimicrobials, brighteners, delustrants, flame retardants, lubricants, and dyestuffs.
• a lubricant can be deposited on the surface of the elastic filaments by a conventional finish roll or by being co- spun with the filament from the polymer solution, or by both methods.
• the dry-spun spandex yarn is then wound up to form a yarn supply package.
• the elastic yarns can be a monofilament yarn or a multifilament yarn and have a fineness of at least about 20d, at least about 30d, at least about 45 d, orat least about 70d.
• the elastic yarn in the warp knit fabric, is a spandex yarn having an elongation at break of 100% or greater and a fineness of about 20-70 deniers.
• the content of elastic yarns employed in the warp knit fabric ranges from about 10 weight%> to about 30 weight%>, or from about 15 weight%> to about 25 weight%>, wherein the weight percentage is based on the total weight of the warp knit fabric.
• the appropriate gauge of a tricot knitting machine is selected according to the uses of the warp knit fabrics, particularly when used in garments that include swimwear, sportswear and intimate apparel.
• the gauge number of the tricot knitting machine is one of the many factors affecting the stretchability and basis weight of the resulting fabric. In the present invention, a 32 gauge is preferred over a 28 gauge tricot knitting machine.
• the method uses a 32 gauge, 130 in. (330 cm) wide tricot machine.
• FIG. 2 illustrates a typical tricot machine. They rarely have more than four guide bars, most use two guide bars.
• the hard yarn e.g., PTT yarn is mounted on the front warp 31 and elastic yarn, e.g., spandex yarn is mounted on the back warp 32.
• the warp tension is controlled by a warp tension rail 33.
• the loop formation activity is controlled by knitting elements 34 which are motored by a main eccentric shaft knitting element drive 37.
• a fabric take-up roller 35 and rolled on the take-up beam 38 The whole tricot knitting machine is supported by a machine bed 36.
• FIGs. 3A-3E illustrates the knitting action of spring beard needles.
• Fig. 3A shows the needle moves upward (as indicated by the arrow) and the previously formed loop slides down to the needle stem 41.
• Fig. 3B a yarn 42 wraps around the needle through the action of the yarn guide 43.
• the needle continues to rise up (in Fig. 3C)
• the yarn 42 slides onto the needle stem 41.
• the needle begins its descent in Fig. 3D.
• the yarn slides inside the beard 44, the presser bar 45 moves forward to close the beard 44, and the old loop slides off the closed beard as the needle moves downward, and the presser bar 45 retracts.
• Fig. 3E the needle continues downward, the yarn inside the beard 44 passes through the old loop and the old loop slides off the needle to complete a loop.
• FIG.4A shows the simplest form of two-bar warp knit fabrics, known as single tricot pattern, which is a basic one-face warp knitting, in which the guide bars move in opposition and make closed laps, moving one needle space right and left alternatively after each course.
• the hard yarns 10 in black are supplied by the front guide bar and the elastic yarns 20 (in white) are supplied by the back bar.
• FIG.4B shows the locknit pattern, in which the guide bars move in opposition at all times, but the overlap of the underlaps is always over one needle space, the underlaps thus are different from that of a single tricot pattern.
• the front guide bar makes a two needle space move while the back guide bar moves only one needle space and in opposite direction.
• the face (or front side) of the fabric shows almost vertical wales with a fine smooth texture, whereas the back (or reverse side) of the fabric is comparatively coarse because of the longerunderlaps made by the front bar.
• the structure of the fabric is that the threads carried by the front guide bar (i.e. PTT yarns) are more prominent on the reverse side, where the diagonal floats, shown in black lines in FIG.4B. It is known that in all two-bar warp knit fabrics, there is a tendency for the yarns of the front guide bar appearing most prominently on the face of the fabric. Therefore, the PTT yarns, which are supplied from the front guide bar, become the main contributor for good hand feel of the warp knit fabrics.
• Front guide bar (PTT yarn): 2-3/1-0//;
• Back guide bar (elastic yarn): 1-0/1- 211, and repeat.
• the main factor controlling the fabric quality is the rate of "run-in length" of each warp, i.e. the total length of yarn supplied from each warp during one rack, i.e. 480 courses. Because the locknit pattern requires the yarns of the front bar to supply the greater length in the underlap, it is known that in producing the locknit fabric the ratio of the front bar to the back bar run-in length is approximately 4:3 (or 1.33). However, the optimal run-in ratio between PTT yarn and elastic yarn is still a matter for determination by trial and error rather than precise calculation.
• the method for producing commercially useful warp knit fabrics of locknit pattern comprises elastic yarns and PTT yarns by maintaining the elastic yarn to have a total draft in the range of 2.6 times to 4.0 times, which is calculated by equation (1) as follows:
• RIp pt run-in length of the PTT yarns, which ranges from about 1400- 2000 mm/rack;
• RI e run-in length of the elastic yarns, which ranges from about 200- 1000 mm/rack;
• SD spool draft of the elastic yarns, which is 1.0 time.
• the present invention has identified that improved results are obtained over the prior art when the total draft of elastic yarn is in the range of from 2.6 times to 4.0 times, preferably from 2.8 times to 3.6 times, and more preferably from 3.0 times to 3.4 times.
• the tension of elastic yarn is kept at about 1-2 g.
• the tension is sufficiently high for reliable and continuous feeding of the elastic yarn to the knitting needles, and sufficiently low to keep the beam draft of the elastic yarn to be at about 1.7 times.
• the ratio of RI p tt:RI e is 2.0 or greater.
• the ratio of RI p tt:RI e is in the range of 2.2 to 2.8.
• Another aspect of the invention includes the use of the warp knit fabrics of locknit pattern for garments, which may include swimwear, sportswear and intimate apparel. Finishing Process of the Greige Fabric
• the warp knit fabric is called greige fabric.
• the greige fabric is finished in the process illustrated diagrammatically in FIG. 6 designated as 50.
• the greige fabric obtained from the knitting process is processed through wet processes of scouring (cleaning), is also called relaxation 51.
• the relaxed fabric is then applied to a tenter frame and heat set in a heat set machine.
• the tenter frame holds the fabric on the edges by needle chains, and stretches it in both the length and width directions in order to return the fabric to desired dimensions and basis weight.
• This heat setting 52 is accomplished before subsequent wet processing steps and, consequently, heat setting is often referred to as "pre-setting" in the trade.
• the flat fabric is released from the needle chains.
• the fabric then is processed optionally, through path A: bleaching 53, or path B: dyeing 54, by over-flow jet equipment.
• path A the fabric can be subjected to the printing process to make printed fabric.
• bleaching 53 or dyeing 54 the fabric is dried and heat set 55 in a tenter-frame oven under conditions of fabric overfeed (opposite of stretching) so that the fabric is under no tension in the length (machine) direction while being dried at temperatures below pre-setting temperatures.
• the fabric is slightly tensioned in the width direction in order to flatten any potential wrinkling.
• Stretching and heat setting parameters are chosen to yield the desired fabric basis weight and elongation, within relatively tight limits.
• the desired elongation in the warp direction is at least 100%, and the basis weight is about 100 g/m 2 or more for intimate apparel, and about 150 g/m 2 or more for swimwear or sportswear.
• Heat setting of dry fabric in a tenter frame or other drying apparatus is also known as re-deniering, wherein an elastic yarn of higher denier is drafted, or stretched, to a lower denier, and then heated to a sufficiently high temperature for a sufficient time to stabilize the elastic yarn of the fabric at the lower denier.
• Heat setting therefore means that the elastic yarn of the fabric permanently changes at a molecular level so that recovery tension in the stretched elastic yarn is mostly relieved and the elastic yarn becomes stable at a new and lower denier.
• the heat setting operation therefore improves the stability of the fabric, and reduces the amount that the fabric will shrink after repeated washings.
• Heat setting temperatures for elastic yarn are generally in the range of about 175°C to about 200°C.
• the heat setting 52 for the warp knit fabric is typically done at about 180°C to about 190°C for about 30 seconds or more.
• the warp knit fabric is delivered to a finish/dry step for an optional finish application (e.g., softener by padding) and subsequent heat set in a heat set machine under conditions of fabric length overfeed.
• finish application e.g., softener by padding
• softeners such as SURE SOFT® or SANDOPERM SEI® are typical.
• the final heat set step is operated with controlled, high fabric overfeed in the length (machine) direction so that the fabric stitches are free to move and rearrange without tension. A flat, non-wrinkled or non-buckled fabric emerges after final heat set. These techniques are familiar to those skilled in the art.
• the fabric final heat set temperature and residence time are set below the values required to pre-heat set the spandex yarn. In one embodiment, in the method of the invention, the final heat set temperature is at the range of 160-170°C for about 30 seconds or more.
• the warp knit fabric of locknit pattern manufactured by the method of the present invention, generally has a basis weight of about 180 g/m 2 or greater.
• the basis weight of the warp knit fabrics used herein will range from about 180 g/m 2 to about 250 g/m 2 , or from about 190 g/m 2 to about 230 g/m 2 .
• the warp knit fabrics of this invention have a basis weight of about 180 g/m 2 or greater, or from about 180 g/m 2 to about 250 g/m 2 , or from about 190 g/m 2 to about 230 g/m 2 .
• the warp knit fabric has an elongation of from about 120% to about 185%, or from about 130% to about 175% in the warp direction; an elongation of from about 80% to about 150%, or from about 105% to about 135% in the weft direction.
• the warp knit fabrics are useful in various durable or repeated-use fabric applications such as, but not limited to, garments including swimwear, sportswear, and intimate apparel.
• the warp knit fabrics of the invention also has a shrinkage after washing and drying of about 7% or less, typically, 5% or less, for example less than about 4% in both warp and weft directions.
• Another aspect of the present invention is to provide warp knit fabrics of a locknit pattern with softer hand feel, higher durability, and better colorfastness in terms of resistance to degradation by chlorine and UV radiation when compared to known stretchable fabrics made with nylon/spandex or PET/spandex.
• Comparative Example is followed by a number indicating in which example the warp knit fabric is prepared. Percentages are by weight unless otherwise indicated.
• Polytrimethylene terephthalate fiber of 50d/24f FDY (fully drawn yarn), was made from DuPont Sorona® polymer (IV 0.96, semi-dull, contains 0.3%> of Ti0 2 ). The elongation at break is 60%>, tenacity is 3.1cN/dtex, spinning oil is 1.7%, boil water shrinkage is 6.9%.
• Spandex monofilament yarn of 40d obtained from INVISTA, Wichita, KS, elongation at break of 550%, tenacity is lg/denier, coated with 3.5% spin oil.
• FIG. 1 A beam for PTT yarn or spandex yarn (1) is illustrated in FIG. 1, which has
• the beaming was conducted on a SH1200 beam machine.
• the beaming tension was set to be about 3-4 g, and beaming speed was 500 m/min.
• the greige fabric was knitted on a Karl Mayer 32E tricot knitting machine of 130 inches wide.
• the PTT yarns were fed from the front guide bar and the spandex yarns were fed from the back guide bar.
• the knitted pattern of the warp knit fabric was a locknit pattern as shown in FIG. 4B.
• Run-in length of the PTT yarns ranged from 1400 mm/rack to 1650 mm/rack, and run-in of the spandex yarn ranged from 500 mm/rack to 650 mm/rack.
• the knitting machine was running at a speed of 2000 courses/min.
• the fabric density is in the range of 18 courses/cm to 30 courses/cm.
• the knitting parameters for each fabric sample are listed in Table 1.
• the greige fabric was produced at a length of about 100-120 meters and a width of 140- 150cm (or 55-59 inches).
• the warp knit fabric sample was scoured, pre-heat set, dyed, and dried per the process as shown in FIG. 6.
• the fabric was scoured in a scouring machine (LMH988 made by Nantong Jingwei textile machinery co., Ltd.) to remove the impurities, oils etc, using 0.5-1 g/L of hydrosulfide, 1-2 g/L of non-ionic detergent, 1-2 g/L of NaOH to adjust pH to 8-10, optional with 1-2 g/L of hydrogen peroxide (when bleaching is required); processed for 30 minutes at 90°C without width tension, rinsed with water or acetic acid containing water at 60°C for 10 minutes.
• LSH988 made by Nantong Jingwei textile machinery co., Ltd.
• the fabric was then pre-heat set at 185°C for 50-60 seconds on a
• MONFORTS tenter frame with 20-30% expanding on width and 10-15% elongation on length direction.
• the fabric after pre-setting was put into a dyeing machine (Fong's ECO 06 made by Fong's) with a programmed dyeing temperature profile.
• the dye bath started with heating to 50°C and holding the bath temperature for 10 min, then raising the bath temperature at 2°C/min to 80°C, further raising the bath temperature to 115°C at l°C/min, and then holding the bath temperature for 30 min to ensure the dyeing completion. Afterwards, the dye bath was cooled down to 60°C at a rate of 2.5°C/min, letting the bath further cool down to ambient temperature naturally.
• the dye solutions contained 1-2% of a disperse dye, 0.5% "Merpol” LFH (low foam non-ionic surfactant, purchased from Guangzhou Diecheng Trading Co., Ltd). 0.5%) "Versene” 100 (sequestering agent, purchased from Guangzhou Diecheng Trading Co., Ltd.), and 0.5% CH 3 COOH to maintain the solution at pH5.
• the dye bath ratio of dye solution to dry fabric weight is 10: 1.
• Two disperse dyes were used to obtain fabric sample of blue and white color, respectively; for blue color: the dye stuff was purchased from Clariant under the tradename of Foron® RD-E; for bleach white color: the bleach was purchased from Clariant under the tradename of Peractive ® TAED.
• the fabric was rinsed with over flow at room temperature for 10 min. After dyeing, the fabric was cleaned at 80°C for 30 min with a solution containing 2.0 g/L SP-3030 (soaping agent, purchased from Guangzhou Zhuangjie Chemical Co., Ltd), 2.0 g/L NaOH, and 2.0 g/L sodium hydrosulfite. Then fabric was soaked at 60°C for 10 min with a solution having 2.0 g/L CH 3 COOH, followed by rinsing with water at room temperature for 10 min.
• SP-3030 silicaping agent
• Comparative tricot warp knit fabric 1 was made from 40 deniers spandex yarns and 40 deniers nylon 6 yarns, containing 20 weight% spandex yarns and 80 weight% of nylon yarns, having a basis weight of 200 g/m 2 and manufactured by Charming (Guangdong, China).
• Comparative tricot warp knit fabric 2 was made from 40 deniers spandex yarns and 40 deniers polyethylene terephthalate (PET) yarns, containing 20 weight% spandex yarns and 80 weight% PET yarns, having a basis weight of 200 g/m 2 , and manufactured by Huiyi (Guangdong, China).
• PET polyethylene terephthalate
• Fabric sample was slit into a size of 50 mm x 150 mm, in a way that the length of the sample is aligned with the weft or warp direction of the fabric.
• the fabric was clamped in the jaws of the Instron machine with a sample length set at 100 mm under up to a force of 3.6 Kg and at an elongation speed of 500 mm/minute. Cycled twice between zero extension and the specified force. From the force versus extension graph produced on the 2 nd cycle, an elongation at the load of 3.6 Kg was reported.
• Fabric Weight Knit fabric samples were die-punched with a 10 cm diameter die. Each cut-out knit fabric sample was weighed in grams. The "fabric weight” was then calculated as g/m 2 .
• (F) UV resistance test The fabric samples were placed with the comparison standards, and exposed to UV radiation according to condition specified for option 3 in the method of AATCC 16E. The fabric samples were visually graded for color changes after 10 hours or 20 hours exposure to UV radiation using the Gray Scale for Color Change according to the method of AATCC 16E.
• the warp knit fabrics of Example 1-16 have a total draft of elastic yarn ranging from 2.6 times to 4.0 times , and a course density of 18-30 courses/cm.
• the hand feel of each example was rated into 3 categories: good, better, or best.
• the results in Table 1 suggests that when the total draft of elastic yarn is at the range of from 3.0 times to 3.4 times and the fabric density is between 20-25 courses/cm, the warp knit fabric of locknit pattern can deliver the best hand feel.
• the warp knit fabric of locknit pattern of this invention has a total draft of elastic yarn of from 3.0 times to 3.4 times, and a course density of 20-25 courses/cm.
• Table 2 summarizes other key performance results of the warp knit fabrics of locknit pattern of the invention.
• the warp knit fabrics of Examples 1-16 have a shrinkage in the both warp and weft directions of less than 4%, which is better than the typical industrial requirement, i.e. 5%. Also, the warp knit fabrics of Examples 1-16 have an elongation in the warp direction ranging from 129% to 179%, and an elongation in the weft direction ranging from 87% to about 141%. In order to have a fabric to have comfortable stretch and compression, the elongation in the warp direction is preferably at least 130% or greater and the elongation in the weft direction is preferably at least 105% or greater.
• the modulus at 60% elongation in the weft direction roughly correlates to the hand feel of the fabric samples.
• E2, E4, E6, El 2, E13 and El 5 have a modulus at 60% elongation in the weft direction greater than 400 g; all were rated to have good hand feel (Grade 1) except for E6.
• E7, E8, E9, E10 and El l have a modulus at 60% elongation in the weft direction between 200-290 g; all were rated to have best hand feel (Grade 3).
• Table 3 summarizes data on hand feel, colorfastness of chlorine exposure and UV radiation for Example 10 and comparative elastic fabrics CEl and CE2.
• warp knit fabrics produced by the method described herein have a better hand feel compared to fabrics of CEl and CE2 such as nylon/spandex or PET/spandex having the same locknit pattern, same basis weight, and same weight % of spandex yarns.
• the warp knit fabrics have significantly better colorfastness after chlorine exposure and UV radiation for 10 hours and 20 hours.

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