WARP KNITTED FABRIC AND METHOD OF MANUFACTURING THE SAME

Abstract

A warp knitted fabric includes a non-elastic filament yarns threaded from a first guide bar and knitted in a 1×2 open Koper stitch pattern, and an elastic yarns threaded from a second guide bar and knitted in a 1×1 closed pillar stitch pattern. The elasticity of the knitted fabric composed of the elastic and non-elastic filament yarns are substantially the same in both longitudinal and transverse directions. A method of manufacturing the warp knitted fabric is also disclosed.

Description

FIELD OF TECHNOLOGY

The present application relates to a warp knitted fabric and a method of manufacturing warp knitted fabrics.

BACKGROUND

Existing warp knitted fabrics used in the underwear industry have three major defects.

First, there is a big difference in the elasticity properties (stretch ratio and elastic modulus under specified drawing forces) of the existing warp knitted fabrics in the longitudinal and transverse directions. In other words, one can easily make the longitudinal and transverse stretch ratios of the fabric substantially the same under a specified target force, but can hardly make its elastic modulus forces of both directions the same throughout the stretching path. Hence, this kind of existing warp knitted fabric can only satisfy the requirement of one-way stretch, and is therefore limited in its application in the underwear clothing industry.

Second, the selvage-curling problem of cut fabrics greatly affects the efficiency of garment production and the quality of the finished products. The selvage-curling problem of elastic warp knitted fabrics is one of the biggest issues affecting clothing manufacturers. The solutions in the past include the application of thermal setting with a very high temperature during pre-treatment process and/or the application of stiffening agents during the finishing process. However, these bring negative effects on the dyeing process and the hand-feel of the fabrics. Especially when manufacturing bodysuits from highly elastic, thick and heavy warp knitted fabrics, the selvage-curling problem makes the processes such as degreasing, heat-setting, dyeing or subsequent treatments of the fabrics very difficult.

Third, snagging problem exists in most warp knitted fabrics while satisfying customers' requirement on smoothness and soft hand-feel of underwear fabrics. Different degrees of snagging occur throughout all manufacturing processes from knitting, dyeing and finishing in fabric mills to cutting, sewing and packaging in clothing factories. It even extends to the shelving in the retail boutiques and the wearing by the users. This defect significantly downgrades the final products.

The above description of the background is provided to aid in understanding a warp knitted fabric, but is not admitted to describe or constitute pertinent prior art to the warp knitted fabric disclosed in the present application, or consider any cited documents as material to the patentability of the claims of the present application.

SUMMARY

According to one aspect, there is provided a warp knitted fabric including non-elastic yarns threaded from a guide bar at a front side of a knitting machine and knitted in a 1×2 open Koper stitch pattern, and elastic yarns threaded from a guide bar at a rear side of the knitting machine and knitted in a 1×1 closed pillar stitch pattern, wherein the stretch ratio and elastic modulus under specified drawing forces of the knitted fabric composed of the elastic and non-elastic yarns are substantially the same in both longitudinal and transverse directions. The threading of the non-elastic and elastic yarns can be full threading. The ratio of stitch density of the knitted fabric in the warp to the weft directions may be 2:1 (±15%). The non-elastic yarns can be nylon yarns or polyester yarns. The elastic yarns can be spandex yarns. An article of clothing can be made of the warp knitted fabric disclosed in the application.

According to another aspect, there is provided a method of manufacturing warp knitted fabrics including the steps of (a) knitting non-elastic yarns threaded from at least one guide bar at a front side of the knitting machine in a 1×2 open Koper stitch pattern; and (b) knitting elastic yarns threaded from at least one guide bar at a rear side of the knitting machine in a 1×1 closed pillar stitch pattern, wherein the stretch ratio and elastic modulus under specified drawing forces of the knitted fabric composed of the elastic and non-elastic yarns are substantially the same in both longitudinal and transverse directions. The knitting of the elastic and non-elastic yarns can be carried out by a Raschel warp knitting machine or a Tricot warp knitting machine. The aggregate threading of the at least one guide bar at the front side of the knitting machine can be full threading, the aggregate threading of the at least one guide bar at the rear side of the knitting machine can be full threading. The ratio of stitch density of the knitted fabric in the warp to the weft directions may be 2:1 (±15%). The non-elastic yarns may be nylon yarns or polyester yarns. The elastic yarns may be spandex yarns.

Although the warp knitted fabric disclosed in the present application is shown and described with respect to certain embodiments, it is obvious that equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present application includes all such equivalents and modifications, and is limited only by the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the warp knitted fabric disclosed in the present application will now be described by way of example with reference to the accompanying drawings.

FIG. 1 is a lapping diagram and a chain notation of a non-elastic yarn “A” threaded from the guide bar(s) at the front side of the knitting machine and knitted in a 1×2 open Koper stitch pattern according to an embodiment disclosed in the present application.

FIG. 2 is a loop structure of the technical back of warp knitted non-elastic “A” yarns of FIG. 1.

FIG. 3 is a lapping diagram and a chain notation of an elastic yarn “B” threaded from the guide bar(s) at the rear side of the knitting machine and knitted in a 1×1 closed pillar stitch pattern according to an embodiment disclosed in the present application.

FIG. 4 is a loop structure of the technical back of warp knitted elastic yarns “B” of FIG. 3.

DETAILED DESCRIPTION

Reference will now be made in detail to a preferred embodiment of the warp knitted fabric disclosed in the present application, examples of which are also provided in the following description. Exemplary embodiments of the warp knitted fabric disclosed in the present application are described in detail, although it will be apparent to those skilled in the relevant art that some features that are not particularly important to an understanding of the warp knitted fabric may not be shown for the sake of clarity.

Furthermore, it should be understood that the warp knitted fabric disclosed in the present application is not limited to the precise embodiments described below and that various changes and modifications thereof may be effected by one skilled in the art without departing from the spirit or scope of the appended claims. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims.

The warp knitted fabric of the present application can be manufactured by a Tricot or a Raschel warp knitting machine with at least 2 guide bars, wherein at least one of the guide bars at the front side of the machine is designed for lapping non-elastic yarns on the knitting needles to perform the knitting action, known as a fabric/loop formation process, and at least one of the guide bars at the rear side of the machine is designed for lapping elastic yarns on the knitting needles to perform knitting action. The lapping motion of guide bars at front precedes that of the guide bars at rear but the knitting action for all guide bars takes place at once.

Considering a machine of two guide bars, the guide bar at front, named “guide bar 1”, is made for lapping non-elastic yarns on the knitting needles, and the guide bar at rear, named “guide bar 2”, is made for lapping elastic yarns on the knitting needles at a lagged period of time against that of “guide bar 1” to perform the same knitting action all together. Yarns can be threaded through the guide needles of the two guide bars and knitted in different stitch patterns to form the desired knitted fabric.

According to an embodiment of the present application, a non-elastic yarn “A” is threaded through the guide needles of “guide bar 1” and knitted in a 1×2 open Koper stitch pattern. FIG. 1 shows a lapping diagram and a chain notation of the non-elastic yarn “A” threaded through the guide needles of “guide bar 1” and knitted in a 1×2 open Koper stitch pattern. The non-elastic yarn “A” may be nylon, polyester, acrylic, polypropylene, viscose, silk, cotton or any other suitable non-elastic yarn. A loop structure of the technical back of warp knitted non-elastic yarns “A” is shown in FIG. 2.

According to an embodiment of the present application, an elastic yarn “B” is threaded through the guide needles of “guide bar 2” and knitted in a 1×1 closed pillar stitch pattern. FIG. 3 shows a lapping diagram and a chain notation of the elastic yarn “B” threaded through the guide needles of “guide bar 2” and knitted in a 1×1 closed pillar stitch pattern. The elastic yarn “B” may be spandex, or any other elastic yarn having substantially the same characteristics of spandex. A loop structure of the technical back of warp knitted elastic yarns “B” is shown in FIG. 4.

According to an embodiment of the present application, the method of threading for both non-elastic and elastic yarns is full threading. The term “full threading” can be considered as one of the threading methods for the guide bar(s) that allows all knitting needles of the machine are lapped with a yarn of a particular type from the corresponding guide needles of one or more threaded guide bars.

The elasticity properties of the knitted fabric composed of the non-elastic yarns “A” and elastic yarns “B” are substantially the same in the longitudinal (warp) direction and the transverse (weft) direction. The ratio of stitch density of the knitted fabric in the warp direction to that in the weft direction is 2:1 (±15%).

When bodysuits are formed by highly elastic, thick and heavy warp knitted fabrics having the same elasticity properties in both the longitudinal and transverse directions, it only requires normal thermal setting temperature without the need of stiffening agents. This can overcome the problem of selvage curling of cut fabrics, and enhance the dyeability and soft hand-feel of the fabrics. Fabrics of this construction also perform strong anti-snagging effect so as to enhance the quality of final apparel products.

The warp knitted fabric may be composed of non-elastic yarns (e.g. nylon, polyester, acrylic, polypropylene, silk, viscose, cotton, etc.) of different types and fineness and elastic yarns (e.g. spandex) of different elasticity and fineness. By using a Raschel or Tricot warp knitting machine, one can produce high-end warp knitted fabrics for underwear meeting different elasticity and weight requirements for both men and women.

The warp knitted fabric of the present application is suitable for many types of high-end underwear and clothing. It is mainly suitable for highly elastic and comfortable lady's underwear such as panties, brassieres and bodysuits.

To manufacture the warp knitted fabrics of the present application, an operator first determines the article of clothing to be manufactured and the target weight of the finished products. The article of clothing may include panties, brassieres, bodysuits, etc. If lady's panties are to be manufactured, then the finished product may weight about 80-160 g/m². If lady's brassieres are to be manufactured, then the finished product may weight about 150-250 g/m². If lady's bodysuits are to be manufactured, then the finished product may weight about 220-320 g/m².

The operator then selects the types of non-elastic yarns “A” and elastic yarns “B” to be used. The non-elastic yarns “A” to be selected may include nylon, polyester, acrylic, polypropylene, viscose, silk, cotton, etc. The elastic yarns “B” to be selected may include spandex yarns or other elastic yarns having substantially the same characteristics of spandex yarns. For example, one may use 5-50 denier non-elastic nylon yarns and 10-250 denier elastic spandex yarns.

The operator then selects the type of warp knitting machine to be used to manufacture the fabrics. The operator can use Tricot type warp knitting machine of machine gauge starting from E28 to E44 (or a higher than E44 gauge number if available later in the market), or Raschel type warp knitting machine of machine gauge starting from E28 to E40 (or a higher than E40 gauge number if available later in the market). The selected non-elastic yarns “A” and elastic yarns “B” are wound onto rollers or cylinders, known as warp beams, and threaded through guide needles of the front and rear guide bars respectively. For example, a 40-gauge 2-bar Tricot warp knitting machine is sufficiently well to produce the warp knitted fabrics of the present application.

The operator can also determine the ratio of stitch density of knitted fabric in the warp direction and the weft direction. For example, the ratio of stitch density of knitted fabric in the warp direction to that in the weft direction can be set at 2:1 (±15%). For example, the warp-wise density of the finished product may have 165 courses/rows per inch, and the weft-wise density of the finished product may have 81 wales/columns per inch.

After the knitting process, other subsequent processes such as degreasing process, thermal setting process, and dyeing process can be carried out.

The following are examples of manufacturing the warp knitted fabrics of the present application with an indication of basic knitting conditions and physical characteristics of the finish products.

Example 1

Fabric Code: RC3079S

Basic Parameters:

Non-elastic yarns: nylon yarn (10 deniers, 12 filaments, full dull type)
Elastic yarns: spandex yarn (40 deniers, clear type)
Proportion of non-elastic nylon: 61%
Proportion of elastic spandex: 39%
Weight of the finished product: 142 g/m²
Warp density of the finished product: 165 courses/inch
Weft density of the finished product: 81 wales/inch

Physical Characteristic Parameters: (Testing Method L T D—03, 7.5 lbs Stretch Force)

Warp stretch ratio of the finished product: 189% (at 7.5 lbs stretch force)
Weft stretch ratio of the finished product: 189% (at 7.5 lbs stretch force)
Warp elastic modulus of the finished product: 0.35 lbs (at 40% stretch ratio)
Weft elastic modulus of the finished product: 0.32 lbs (at 40% stretch ratio)
Warp elastic modulus of the finished product: 0.64 lbs (at 60% stretch ratio)
Weft elastic modulus of the finished product: 0.54 lbs (at 60% stretch ratio)
Warp elastic modulus of the finished product: 0.95 lbs (at 80% stretch ratio)
Weft elastic modulus of the finished product: 0.79 lbs (at 80% stretch ratio)

Basic Knitting Parameters:

Type of knitting machine: 40-gauge 2-bar high-speed Tricot warp-knitting machine (HKS 2-3E)
Total number of yarns of the first guide bar: 5010
Total number of yarns of the second guide bar: 4992
Runner length of the first guide bar: 1900 mm per rack
Runner length of the second guide bar: 596 mm per rack (beaming at 80% stretch ratio)

Example 2

Fabric Code: RC3293S

Basic Parameters:

Non-elastic yarns: nylon yarn (20 deniers, 17 filaments, full dull type)
Elastic yarns: spandex yarn (80 deniers, clear type)
Proportion of non-elastic nylon: 62%
Proportion of elastic spandex: 38%
Weight of the finished product: 189 g/m²
Warp density of the finished product: 124 courses/inch
Weft density of the finished product: 62 wales/inch

Physical Characteristic Parameters: (Testing Method L T D—03, 7.5 lbs Stretch Force)

Warp stretch ratio of the finished product: 111% (at 7.5 lbs stretch force)
Weft stretch ratio of the finished product: 112% (at 7.5 lbs stretch force)
Warp elastic modulus of the finished product: 1.06 lbs (at 40% stretch ratio)
Weft elastic modulus of the finished product: 0.90 lbs (at 40% stretch ratio)
Warp elastic modulus of the finished product: 1.88 lbs (at 60% stretch ratio)
Weft elastic modulus of the finished product: 1.65 lbs (at 60% stretch ratio)
Warp elastic modulus of the finished product: 3.11 lbs (at 80% stretch ratio)
Weft elastic modulus of the finished product: 2.82 lbs (at 80% stretch ratio)

Basic Knitting Parameters:

Type of knitting machine: 32-gauge 2-bar high-speed Tricot warp-knitting machine (HKS 2-3E)
Total number of yarns of the first guide bar: 4032
Total number of yarns of the second guide bar: 4020
Runner length of the first guide bar: 2160 mm per rack
Runner length of the second guide bar: 600 mm per rack (beaming at 80% stretch ratio)

Example 3

Fabric Code: RC3283SA

Basic Parameters:

Non-elastic yarns: nylon yarn (20 deniers, 34 filaments, round bright type)
Elastic yarns: spandex yarn (40 deniers, clear type)
Proportion of non-elastic nylon: 77%
Proportion of elastic spandex: 23%
Weight of the finished product: 156 g/m²
Warp density of the finished product: 122 courses/inch
Weft density of the finished product: 65 wales/inch

Physical Characteristic Parameters: (Testing Method L T D—03, 7.5 lbs Stretch Force)

Warp stretch ratio of the finished product: 136% (at 7.5 lbs stretch force)
Weft stretch ratio of the finished product: 143% (at 7.5 lbs stretch force)
Warp elastic modulus of the finished product: 0.38 lbs (at 40% stretch ratio)
Weft elastic modulus of the finished product: 0.34 lbs (at 40% stretch ratio)
Warp elastic modulus of the finished product: 0.69 lbs (at 60% stretch ratio)
Weft elastic modulus of the finished product: 0.62 lbs (at 60% stretch ratio)
Warp elastic modulus of the finished product: 1.14 lbs (at 80% stretch ratio)
Weft elastic modulus of the finished product: 1.00 lbs (at 80% stretch ratio)

Basic Knitting Parameters:

Type of knitting machine: 32-gauge 2-bar high-speed Tricot warp-knitting machine (HKS 2-3E)
Total number of yarns of the first guide bar: 4032
Total number of yarns of the second guide bar: 4020
Runner length of the first guide bar: 2050 mm per rack
Runner length of the second guide bar: 550 mm per rack (beaming at 80% stretch ratio)

While the warp knitted fabric disclosed in the present application has been shown and described with particular references to a number of preferred embodiments thereof, it should be noted that various other changes or modifications may be made without departing from the scope of the appending claims.

Claims

1. A warp knitted fabric comprising:

(a) non-elastic yarns threaded from a first guide bar at a front side of a knitting machine and knitted in a 1×2 open Koper stitch pattern; and

(b) elastic yarns threaded from a second guide bar at a rear side of the knitting machine and knitted in a 1×1 closed pillar stitch pattern;

(c) wherein the stretch ratio and elastic modulus under specified drawing forces of the knitted fabric composed of the elastic and non-elastic yarns are substantially the same in both longitudinal and transverse directions.

2. The fabric as claimed in claim 1, wherein the threading of the non-elastic yarns is full threading.

3. The fabric as claimed in claim 1, wherein the threading of the elastic yarns is full threading.

4. The fabric as claimed in claim 1, wherein the ratio of stitch density of the knitted fabric in the warp to the weft directions is 2:1 (±15%).

5. The fabric as claimed in claim 1, wherein the non-elastic yarns are nylon yarns.

6. The fabric as claimed in claim 1, wherein the non-elastic yarns are polyester yarns.

7. The fabric as claimed in claim 1, wherein the elastic yarns are spandex yarns.

8. A method of manufacturing warp knitted fabrics comprising the steps of:

(a) knitting non-elastic yarns threaded from at least one guide bar at a front side of a knitting machine in a 1×2 open Koper stitch pattern; and

(b) knitting elastic yarns threaded from at least one guide bar at a rear side of the knitting machine in a 1×1 closed pillar stitch pattern;

(c) wherein the stretch ratio and elastic modulus under specified drawing forces of the knitted fabric composed of the elastic and non-elastic yarns are substantially the same in both longitudinal and transverse directions.

9. The method as claimed in claim 8, wherein the knitting of the elastic and non-elastic yarns is carried out by a Raschel warp knitting machine.

10. The method as claimed in claim 8, wherein the knitting of the elastic and non-elastic yarns is carried out by a Tricot warp knitting machine.

11. The method as claimed in claim 8, wherein the aggregate threading of the at least one guide bar at the front side of the knitting machine is full threading.

12. The method as claimed in claim 8, wherein the aggregate threading of the at least one guide bar at the rear side of the knitting machine is full threading.

13. The method as claimed in claim 8, wherein the ratio of stitch density of the knitted fabric in the warp to the weft directions is 2:1 (±15%).

14. The method as claimed in claim 8, wherein the non-elastic yarns are nylon yarns.

15. The method as claimed in claim 8, wherein the non-elastic yarns are polyester yarns.

16. The method as claimed in claim 8, wherein the elastic yarns are spandex yarns.

17. An article of clothing made of the warp knitted fabric as claimed in claim 1.