WO2018142427A1

WO2018142427A1 - A knitted workwear fabric and a process for preparation thereof

Info

Publication number: WO2018142427A1
Application number: PCT/IN2018/050055
Authority: WO
Inventors: Satyapriya DASH; Sunny SHARMA; Vipul Patel; Manoj DIXIT
Original assignee: Arvind Limited
Priority date: 2017-02-04
Filing date: 2018-02-02
Publication date: 2018-08-09

Abstract

A knitted workwear fabric and a process for preparation thereof is disclosed. The knitted workwear fabric comprises of a vortex spun yarn and a filament yarn knitted with a plated knitted structure. The present invention also provides a process for preparation of the knitted workwear fabric. The knitted workwear fabric of the present invention provides dimensional stability and high pilling resistance properties. The fabric of the present invention is low in weight with excellent abrasion, wash and light fastness and a highly durable fabric.

Description

PR E PA RATION T H E R E O F

FIE L D O F T H E INV E NT IO N

The present invention relates to workwear fabrics and a process for preparing workwear fabrics.

£ BAC K G ROU ND O F T H E INV E NT ION

Workwear is a dress worn, by manual labour employed within industries for work, as workwear provides safety to the user. Workwear clothing directly affects productivity and efficiency of the manual labour if he/she finds it uncomfortable to wear at working environment. Hence, workwear must be durable and have high

3 dimensional stability, high abrasion resistance, good crease recovery, high resistance to pilling, comfortable to wear during active as well as passive conditions. Therefore, not only functional properties such as durability, strength, high colour fastness, abrasion resistance, pilling resistance and crease recovery but also the aesthetic properties comprising soft feel, breathability/Moisture

¾ vapour transfer rate, sweat absorbent air permeability and the like are equally important.

Generally, workwear garments/apparels are made from woven fabrics due to their high dimension stability. K nitted fabrics are not used and preferred as workwear fabric due to the low dimensional stability. For example, shrinkage of the knitted fabrics is more than 5% due to low twist level in yarn which results into pilling on the fabric and low strength. Therefore, traditionally, the woven 100% cotton fabric comprising Canvas, Denim, Corduroy are mostly preferred as workwear in order to have more strength and durability. However, cotton fabrics used as workwear are generally of 350 to 500 GSM which makes the workwear heavy and therefore it is observed that the cotton workwear are not comfortable for work. Workwear made of cotton and a synthetic fibre blend are also known in the art which include Polyester or Nylon 66 blended with cotton. The blending reduces

¾ GSM in a range of 250 to 280. However, it is observed that these synthetic fibre blends have pilling problem which leads to surface defect and is considered as unsightly. Various efforts have been made including giving workwear fabrics stiff finish to have more surface friction. Though, it increases pilling resistance and crease recovery which solves pilling problem to an extent, but the feel of the fabric becomes uncomfortable to the wearer/user which directly affects productivity and efficiency of the user.

Accordingly, there is a need of workwear and process for preparation thereof which overcomes at least one of the drawbacks of the prior art. & SU M MA RY OF T H E INV E NTION

Accordingly, in the first aspect, the present invention provides a process for preparation of knitted workwear fabric comprising steps of providing a knitted fabric having a plated structure of spun yarn on a face end and synthetic filament yarn on a back end of the fabric. The knitted fabric is knitted in a loop and stitch arrangement such that a vortex spun yarn on a face-end passes through a filament yarn on a back-end to form a plated structure of the fabric by using a two feeder mechanism. Next step involves wet processing of the knitted fabric by scouring for removing natural impurities therefrom. Optionally, dyeing of plated structure of the fabric is done. In a next step, the fabric of the above step is subjected to hot wash followed by acid neutralisation and cold washing. The washed knitted fabric is then further subjected for opening operation in slitting machine to open width thereof, wherein the slitting fabric runs at a predefined speed. Further step

¾ involves drying of the wet opened fabric on a Stenter at a predefined temperature followed by a heat setting above a glass transaction temperature of synthetic filament yarn for facilitating thermal stability of the dried fabric. Generally, the heat setting temperature ranges from 170eC to 200eC. However, it depends upon the type of the synthetic filament and fibres used for the fabric. Further, the

3 thermal stability of the dried fabric reduces to -0.5% to 0%. In the final step, the fabric is subjected on a compacter to allow shrinkage in length and width of the fabric for providing permanent dimensions thereby providing a knitted fabric for workwear.

In an embodiment the process may comprise a step of applying chemical finish ¾ through a padding mangle of the Stenter for imparting antimicrobial finishing to the fabric on a Stenter using antimicrobial and softening agents. According to the present invention, the antimicrobial agent is selected from a group including quaternary ammonium, metallic salts of Ag, Zn, Cu, Triclosan (2,4,4-hydrophenyl trichloro (II) ether), chitosan, and the like.

In another aspect, the present invention provides workwear fabric made from a knitted fabric, said work wear comprising a plated structure of first yarn on a face end and a second yarn on a back end of the fabric. The said first is a vortex spun yarn and said second yarn is a synthetic filament yarn. The said workwear fabric has a thickness in a range from about 160 GSM to about 450 GSM and the abrasion resistance more than 1,00,000 revolution which is five times more than conventional fabrics.

According to the present invention, the vortex spun yarns comprises natural fibres ¾ or a blend of 100% natural fibres and synthetic fibres comprising at least 45% synthetic fibres. Further, yarn count of vortex yarn varies from 24-40 ^"s Ne and yarn count of the synthetic filament yarn varies from 75 denier to 150 denier.

B RIE F DE SC RIPT ION OF D RAWINGS:

3 FIG. 1 is a loop diagram of plated structure of a knitted workwear fabric constructed in accordance with the present invention;

FIG. 2A is a front view of a feeder mechanism adapted for positioning of a filament yarn and a vortex spun yarn during processing of the knitted workwear fabric; and

¾ FIG. 2B is a top view of the feeder mechanism of FIG. 2A.

DE TAIL E D DE SC RIPTION OF T H E INV E NT ION

Although specific terms are used in the following description for sake of clarity, these terms are intended to refer only to particular structure of the invention sel ected f or i 11 ustrati on i n the drawi ngs and are not i ntended to defi ne or I i mit the scope of the invention. References in the specification to ^'preferred embodiment_, means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention. The present invention is illustrated with reference to the accompanying drawings, ¾ throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

In one aspect, provided herein is a process for preparation of a knitted workwear fabric.

3 In another aspect, provided herein is a knitted workwear fabric, and a process for preparation thereof in accordance with a preferred embodiment of the present invention.

In general, the present invention provides a process for preparing a workwear fabric from a knitted fabric and a workwear fabric thereof. The process for ¾ preparing a workwear fabric includes generally steps of providing a knitted fabric made from a vortex spun yarn and synthetic filament yarn, followed by wet processing, washing, opening, drying, heat setting and finally compacting to prepare the knitted fabric for workwear having permanent dimensions. The workwear fabric thus provided has a thickness in a range from about 160 GSM to about 450 GSM and the abrasion resistance more than 1,00,000 revolution which is five times more than conventional fabrics. According to the present invention, the vortex spun yarns comprises 100% natural fibres or a blend of natural fibres and synthetic fibres comprising at least 45% synthetic fibres. Further, yarn count of vortex yarn varies from 24-40~s Ne and yarn count of the synthetic filament yarn varies from 75 denier to 150 denier.

The detailed process for preparation of knitted workwear fabric is described in detail hereinafter:

¾ In an embodiment, referring to FIG. 1, the present invention provides a knitted workwear fabric. The knitted fabric (100) comprises a first yarn (110) and a second yarn (120) knitted with a circular knitted plated structure. Advantageously, the circular knitted plated structure matrix is formed by filament and vortex spun technology. In accordance with a preferred embodiment of the present invention,

3 the first yarn (110) is a vortex spun yarn and the second yarn (120) is a filament yarn. According to the present invention, the vortex spun yarns comprises natural fibres or a blend of natural fibres and synthetic fibres comprising at least 45% synthetic fibres. Further, yarn count of vortex yarn varies from 24-40 ^"s Ne and yarn count of the synthetic filament yarn varies from 75 denier to 150 denier. It is

¾ to be noted that the filaments give dimensional stability, strength, and spun through vortex system gives high pilling resistance properties.

In the context of the present invention, maximum strength at filament stage is achieved by having the filament structure in fabric with good dimensional stability, wherein the second yarn (120) is projected on back structure and the first yarn (110) is projected on face structure. The combination of the first and the second yarn not only overcomes circular knitted structure lacuna but also reduces the GSM less than 230 with soft feel. In accordance to the present invention, the filament yarn (120) is advantageously located on the back side of the fabric which gives dimensional stability and a stable structure to the knitted workwear fabric of the present invention. T he vortex spun yarn (110) is advantageously located on front side which gives aesthetic look

¾ and smooth hand feel to the knitted workwear fabri c of the present i nventi on.

Referring to FIG. 2 shows a two-feeder mechanism (200) for preparing a knitted fabric as shown in FIG 1. As per the method of preparing workwear fabric of the present invention, in an initial step, a plated structure of the fabric (100) is formed using the two-feeder mechanism (200), wherein a loop and stitch arrangement is

3 made such that a vortex spun yarn (110) is on a face-end passes through a synthetic filament yarn (120) on a back-end. Preferably, the two yarns (110), (120) are inserted at same time on the two-feeder mechanism (200). The two- feeder mechanism 200 includes an upper hole (210) and a lower hole (220) such that the synthetic filament yarn (120) is passed through the upper hole (210) and

¾ the spun yarn (110) is passed through the lower hole (220). Accordingly, the filament yarn (120) which is passed through the upper hole (210) forms a back side of the fabric (100) and the vortex spun yarn (110) which is passed through the lower hole (220) forms a face side of the fabric (100). In accordance with the preferred embodiment, the synthetic filament yarn includes polyamide (nylon, nylon 66), polyester, acrylic and the like. According to the present invention, the filament yarn may be subjected to coloration at melt spinning stage in order to prevent the colour to come out during washing, rubbing, bleaching or exposure to sunlight thereby facilitating excellent fastness properties to washing, light, perspiration, water and bleach.

Next step is the wet processing step wherein the knitted fabric obtained in earlier step is subjected for removal of added impurities like spin oil, handling stain

¾ during knitting and the natural impurities in cotton fiber. In this step, the knitted fabric is subjected to scouring treatment in a soft flow machine wherein the knitted fabric is loaded in a rope form and subjected to scouring. In this one particular embodiment, the knitted fabric in loop form is given a hot wash with water and lubricant at a temperature of 60eC for a time period of 10 minutes

3 followed by a scouring treatment with chemicals namely 2% of NaOH, 2% H₂0₂,

2 gm/lit of sequestering agent, 2 gm/lit of lubricating agent 1 gm/lit of defoaming agent for a temperature of about 85eC to about 90eC and a time period of 30 minutes. It is understood here that NaOH facilitates alkali hydrolysis such that all the oil type impurities like oil, grease, natural wax and other natural impurities in

¾ cotton are removed. It is further understood that H₂0₂ removes the natural colour of cotton and makes the fabric brighter and absorbent. The wet process may further include a step of dyeing the knitted fabric.

After wet processing, the fabric is subjected with a hot wash followed by acid neutralisation and cold wash that facilitates the fabric free from added as well as natural impurities thereby resulting into a more absorbent and clean fabric. In next step, the washed knitted fabric is subjected to opening operation on a slitting machine to open width of the knitted fabric to process on next machine, wherein the si itti ng fabri c runs at a speed of 30 mtr/mi n. In next step, the width opened knitted fabric which is wet, is dried on a Stenter at a predefined temperature followed by heat setting above a glass transaction temperature of synthetic filament yarn for facilitating thermal stability of the dried fabric. The drying temperature ranges from about 110eC to 130eC. It is

¾ understood here that the dried and slit fabric is sent to a Stenter to open a width thereof. The Stenter operates at a predefined temperature and for a time period of 30 seconds. The Stenter not only dries the fabric but also makes the fabric thermally stable by giving heat treatment above the glass transaction temperature of synthetic filament yarn which is known as heat setting.

3 In the Stenter, a chemical finish may be applied through a padding mangle of the

Stenter to facilitate antimicrobial finish followed by removal of skew and bow arrangement.

According to the present invention, the chemicals are added into the padding mangle preferably when the fabric passes to the padding mangle such that the ¾ fabric picks up the chemicals to have antimicrobial finish thereon. In this one preferred embodiment, the chemicals include a predefined amount of antimicrobial agent, a predefined amount of hydrophilic softener and a predefined amount of polyethylene softener. Preferably, the antimicrobial agent is present in an amount of 8 gm/lit. According to the present invention, the antimicrobial agent is selected from a group including quaternary ammonium, metallic salts of Ag, Zn, Cu, Triclosan (2,4,4-hydrophenyl trichloro (II) ether), chitosan, and the like. The hydrophilic softener is present in an amount of 10 gm/lit. The hydrophilic softeners are selected form polyethylene, polyurethane, silicon base hydrophilic softener, and the like. The antimicrobial agent facilitates antimicrobial properties to the fabric. The antimicrobial finish provides protection against microbes and avoids bad odour by killing harmful bacteria. The durable antimicrobial finish is bacteriostatic and gently defensive. The durable antimicrobial neutralizes odour-

¾ causing bacteria on contact keeping textiles fresher for longer, without affecting the skins natural balance. The durable antimicrobial finish advantageously immobilizes the bacteria by depleting oxygen, subsequently ruptures the bacterial cell membrane and destroys the reproductive receptor. The hydrophilic softener facilitates absorbent properties to the fabric thereby enhancing soft hand feel. The

3 polyethylene softener facilitates surface smoothness to the fabric. The dried treated fabric then is sent to compacter to shrink in length as well as width of the fabric for providing permanent dimensions to the knitted fabric that can be used as workwear fabric. The fabric is shrink in such a way that the shrinkage ratio reduces below -2.5%.

¾ The vortex spun yarn and filament yarn advantageously form a matrix that gives substantially good capillary properties to the knitted workwear fabric thereby acting as an advance moisture management system. Hence, the fabric of the present invention is advantageously suitable for active as well as passive wear, which is prime requirement of workwear garment. The knitted workwear fabric of the present invention has a high pilling resistance, greater abrasion and high crease recovery angle properties due to the structure without any chemical treatment. The knitted workwear fabric has high level of abrasion, pilling resistance, light and wash fastness, breathability, dimensional stability, and crease recovery without chemical treatment. The knitted workwear fabric of the present invention is more durable and comfortable compared to any knitted and woven fabric of similar weight range. The knitted workwear fabric of the present invention is breathable thereby having air permeability and moisture permeability

¾ which helps to reduce perspiration and provides greater comfort to the user for longer period. The knitted workwear fabric of the present invention has very high light and wash colour fastness. The knitted workwear fabric of the present invention has a substantially high dimensional stability. Thus, the present invention provides a workwear fabric which not only meets functional properties

3 but also provides the aesthetic properties to a greater level which result in increase of productivity and efficiency of work personnel.

The knitted workwear fabric of the present invention has tested as per ASTM E- 96-05 and found having a very high moisture vapour transmission rate (MVTR) which is observed to be 2585.5 gm/M2/Day in comparison to commercially ¾ available workwear cloth which have MVTR 1200 to 1500 gm/M²/Day. The knitted workwear fabric of the present invention has also tested for a very high abrasion resistance, and the results proved that the knitted workwear fabric has abrasion resistance more than 100000 Revolution which is at I east five times more than in comparison to commercially available workwear clothing which have abrasion resistance in a range of 20000 to 60000. Test results of one of the non- limiting composition of the workwear knitted fabric is given in Example 1 below: E xample 1 :

A workwear knitted fabric was prepared by a process as per the invention disclosed and claimed herein. The Y arn count of poly/cotton vortex spun yarn of the fabric was 30 ^"s Ne having by weight 85% polyester fibers and 15% cotton while polyester yarn of 100 denier was used as synthetic filament yarn for preparing the workwear knitted fabric. The workwear fabric had weight 210 GSM. The fabric was tested under various standards defined for workwear fabric, and the test result are given in the table 1 below:

The tests showed that the knitted fabric prepared by the process can be used as workwear fabric.

The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable ¾ others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.

The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description

3 rather than of I i mi tati on.

It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and verifications are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. It is also to be

¾ understood that the following claims are intended to cover all of the generic and specific features of the invention described herein.

It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spi rit or scope of the present i nventi on.

Claims

C laims :

1. A process for prepari ng a workwear f abri c compri si ng the steps of:

Providing a knitted fabric having a plated structure of vortex spun yarn on a face end and synthetic filament yarn on a back end of the fabric;

wet processing of the knitted fabric by scouring for removing natural i mpuriti es therefrom;

washing the knitted fabric;

subjecting the washed knitted fabric for opening operation in slitting machine to open width thereof, wherein the slitting fabric runs at a predefined speed;

drying the wet opened knitted fabric on a Stenter at a predefined temperature followed by heat setting above a glass transaction temperature of synthetic filament yarn for facilitating thermal stability of the dried fabric; and

subjecting the dried treated knitted fabric on a compacter for shrinking in length and width of the fabric for providing permanent dimensions thereby providing a knitted fabric for workwear.

2. The process as claimed in claim 1, wherein the scouring agents are selected from the group comprising of NaOH, Η₂0₂, sequestering agents, lubricating agents, defoaming agents and the like.

3. The process as claimed in claim 1 or 2, wherein the temperature for the scouring treatment is in a range from about 85eC to about 90eC.

4. The process as claimed in one of the claims 1 to 3, wherein the time period for the scouring treatment is about 30 minutes.

5. The process as claimed in one of the preceding claims 1 to 4, wherein the wet processing of the knitted fabric includes dyeing of the knitted fabric.

¾ 6. The process as claimed in claim 1, wherein washing step includes hot washing followed by acid neutralisation and cold washing to facilitate the knitted fabric free from added and natural impurities.

7. T he process as clai med i n clai ml , wherei n the si itti ng fabric runs at a speed of about 30 mtr/min.

3 8. The process as claimed in claim 1, wherein the drying temperature is in the range from about 110eC to 130eC .

9. The process as claimed in claim 1, wherein the heat setting temperature is a glass transition temperature of the synthetic filament yarn that includes polyamide (nylon, nylon 66), polyester, acrylic and the like.

¾ 10. T he process as clai med i n clai m 1 or 9 wherei n the heat setti ng temperature is i n a range from about 170eC to 200eC .

11. The process as claimed in claim 1, wherein the thermal stability of the dried fabric reduces to -0.5% to 0%.

12. The process as claimed in claim 1, comprising step of applying chemical finish through a padding mangle of the Stenter for imparting antimicrobial finishing to the fabric on a Stenter using antimicrobial and softening agents.

13. The process as claimed in claim 12, wherein the antimicrobial agent is selected from quaternary ammonium, metallic salts of Ag, Zn, Cu, Triclosan (2,4,4-hydrophenyl trichloro (II) ether), chitosan, and the like.

14. The process as claimed in claim 12, wherein the hydrophilic softeners are ¾ selected form polyethylene, polyurethane, silicon base hydrophilic softener, and the like.

15. The process as claimed in claim 1, wherein the step compacting reduces the shrinkage ratio below -2.5%.

16. The process as claimed in claim one of the preceding claims 1-15, wherein 3 the vortex spun yarns comprises natural fibres or a blend of natural fibres and synthetic fibres comprising at I east 45% synthetic fibres.

17. The process as claimed in claim one of the preceding claims 1-16, wherein yarn count of vortex yarn varies from 24-40 ^"s Ne and yarn count of the synthetic filament yarn varies from 75 denier to 150 denier.

¾ 18. A workwear fabric made from a knitted fabric, said work wear comprising:

a plated structure of first yarn on a face end and a second yarn on a back end of the fabric, said first is a vortex spun yarn and said second yarn is a synthetic filament yarn;

wherein said workwear fabric has a thickness in a range from about 160 GSM to about 450 GSM, shrinkage ratio below -2.5% and the abrasion resistance more than 1,00,000 revolution which is five times more than conventional fabrics .

19. The workwear fabric as claimed in claim 18, wherein the vortex spun yarns comprises 100% natural fibres or a blend of natural fibres and synthetic fibres comprising at I east 45% synthetic fibres.

20. The workwear fabric as claimed in claim 18 or 19, wherein yarn count of vortex yarn varies from 24-40 ^"s Ne and yarn count of the synthetic filament yarn varies from 75 denier to 150 denier.