US20020066145A1

US20020066145A1 - Method for creating a fabric with a colored pattern

Info

Publication number: US20020066145A1
Application number: US09/731,441
Authority: US
Inventors: Sudhir Gupta; Frederick Page; Nitin Jayawant
Original assignee: KUKREJA SUNIL P
Current assignee: KUKREJA SUNIL P
Priority date: 2000-09-29
Filing date: 2000-12-06
Publication date: 2002-06-06

Abstract

A fabric formed from cellulosic fibers is printed with a dye gain print paste including an acrylic copolymer and/or a dye resist print paste including an acrylic copolymer. The fabric may then be cut into garment pieces, which are made up into garment modules, and the garment modules are dyed.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of Provisional Application No. 60/236,631 filed Sep. 29, 2000. The entire disclosure of Provisional Application No. 60/236,631 is hereby incorporated by reference herein.[0001]

BACKGROUND OF THE INVENTION

This invention relates to a method for creating a fabric with a colored pattern.

Whether a pattern is perceptible by the human eye depends on the granularity or detail of the pattern. A pattern that is sufficiently coarse to appear as discrete black and white checks or stripes at a distance of one meter would typically appear a uniform gray at a distance of 100 meters. Conversely, a fabric that appears to be uniform gray at a distance of one meter may be seen to be composed of black and white yarns when viewed through a microscope. Thus, the term “pattern” does not imply distribution of color in discrete areas with distinct edges when viewed at a distance of one meter or so but covers a color distribution that may appear uniform at a distance of one meter but when viewed more closely can be seen to be a blend of discrete areas with distinct edges.

A fabric garment can be made by forming a fabric from textile yarns, cutting the fabric into garment pieces, and sewing the garment pieces together. The fabric can be made by knitting or weaving the yarns to form knits or woven fabrics or by bonding the yarns to form non-woven fabrics. Color can be imparted to the yarns at four stages: in fiber dyeing, the fibers are dyed in advance of spinning into yarns, and the dyed fibers are spun into yarns; in package dyeing, the yarns are dyed before they are knit or woven to form the fabric; in fabric dyeing, the fabric is dyed after it has been knit or woven but before it is cut into garment pieces; and in garment dyeing, the manufactured garment is dyed.

The conventional garment dyeing process for cellulose fiber (cotton) garments using a reactive (direct) or acid dye involves placing completed garments in a paddle dye (or rotary) machine containing water, adding certain chemicals, including an electrolyte such as sodium sulfate or sodium chloride, to the process bath and allowing the garments to circulate, adding the dye to the bath, and heating the bath at about 3° F. per minute to the exhaust temperature, which depends on the particular dye and is typically 140 to 160° F. When the exhaust temperature is reached, an alkali is added to the bath to begin the exhaustion and fixation of the dye to the cellulose fiber. The bath is held at the exhaust temperature for an extended period of time, which is sufficient for fixation of the dye and may typically be about 45 minutes, and the machine is then drained.

Hitherto, garment dyeing has been unsatisfactory and has not been commercially acceptable for many purposes because dye penetration into the fabric has been poor and non-uniform, particularly at the seams, and excessive abrasion to the fibers has occurred.

Conventionally, a fabric having a colored pattern is created either by weaving or knitting threads of different colors so that the pattern is created as the fabric is created, or by applying coloring medium, such as dye, to the completed fabric in accordance with a spatial pattern. In the latter case, the pattern may be imparted by a printing process using stencil-like screens to define the areas to which coloring medium is applied.

Hand block printing and hand screen printing techniques require relatively modest capital costs but these techniques are not suitable for long print runs and consistency of print is not guaranteed in repeat applications. Moreover, operating costs are high.

Rotary printing machines not only run at high speed but also ensure consistency of prints and better clarity and registration compared to block and screen printing. Further, modern rotary machines can give various designs repeats also.

In the past some attempts have been made to apply dye resist and dye gain agents to cellulosic fabrics and garments by screen printing, either by hand or by machine, but efforts to apply such agents using a high speed rotary printing machine have not been successful.

The commonly available dye resist and dye gain chemicals are not very durable when washed and can be easily felt by hand.

U.S. Pat. No. 5,984,977 discloses a further technique for imparting a colored pattern to fabric. In accordance with this technique, a dye blocking or dye enhancing paste is applied to the fabric by printing, so that some areas of the fabric receive the paste and other areas do not. The fabric is then dyed, and the effectiveness of the dye on the fabric is different on the areas that were printed with the paste than on the areas that were not printed.

In accordance with the disclosure in U.S. Pat. No. 5,984,977, the dye blocking paste includes a pre-catalyzed cross-linking glyoxal resin and a low molecular weight polyacrylic acid and the dye enhancing paste includes an epoxy functional quaternary ammonium compound. Although these pastes are suitable for application to fabric by screen printing, it has been found that they are not suitable for application using a rotary printing machine.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method of creating a fabric with a colored pattern, comprising (a) providing at least first and second yarns, wherein the first yarn has a greater affinity than the second yarn for a selected dye, (b) creating a fabric using at least the first and second yarns, and (c) dyeing the fabric using the selected dye.

The present invention provides several techniques for achieving differential dye pick up during dyeing of fabric, particularly garment dyeing, by printing with a polymer-based dye gain agent and/or a polymer-based dye resist agent. These techniques allow the dye pick up to be increased and/or reduced in selected areas of the fabric relative to other areas. Consequently, when the fabric is dyed, the depth or saturation of the shade is greater in areas that have been treated with the dye gain agent and is less in the areas that have been treated with the dye resist agent, in each case relative to untreated areas. The extent of the difference in depth can be adjusted by controlling the concentration of the dye gain agent or dye resist agent in the printing paste.

In accordance with one aspect, the present invention is applied to fabric that has previously been formed and in accordance with another aspect, the present invention is applied to formation of fabrics from yarns that have been differently treated to achieve differential dye pick up.

Certain acrylic copolymers are particularly advantageous as dye resist and dye gain agents in methods embodying the present invention. For example, a highly anionic copolymer composed of acrylic polymer, pigment (such as titanium dioxide) and softeners is effective as a dye resist agent with respect to anionic dyes, such as reactive, modified reactive and direct dyes, and a highly cationic copolymer composed of acrylic polymer, styrene monomer, acrylate and softeners is effective as a dye gain agent with respect to the same anionic dyes. The acrylic copolymer is synthesized from acrylic monomers, and the cationic (or anionic) nature of the acrylic copolymer is controlled by selecting appropriate monomers from which to synthesize the copolymer. Thus, some monomers will result in the acrylic copolymer being anionic in nature and other monomers will result in the acrylic copolymer being cationic in nature.

DETAILED DESCRIPTION

EXAMPLE I

A first method in accordance with the invention is used to intensify the effect of dye on a fabric. This first method includes five main operations: [0018]
A. Prepare greige fabric for dyeing by the following process: [0019]
1. If the fabric was sized during weaving, the fabric is desized using enzymes. If the fabric was not sized during weaving, omit step 1. [0020]
2. The fabric is placed in a water bath at 380 C and scouring and bleaching agents are added to the water bath. The bath containing the fabric and the scouring and bleaching agents is heated to 95° C. at 2° C. per minute and is held at 95° C. for 45 minutes. The fabric is cooled in steps by several rinses to avoid cracking, which may result in dye streaks during the subsequent garment dyeing process. The pH of the bath is adjusted to the range 6-7 and a peroxide killer is added to the neutralized bath to remove any hydrogen peroxide residues. [0021]
The bleaching and scouring agents are: [0022]
5-6% hydrogen peroxide (50%) [0023]
4-5% caustic soda (50%) [0024]
2-3% peroxide stabilizer (non silicate) [0025]
1% cleaning agent (Sandoclean PCJ) [0026]
1-2% lubricating and wetting agent (Imacol CI) [0027]
0.25-0.5% chelate (sequestrant) [0028]
where percentages are by volume of the water bath. Softeners should be avoided, but if softeners are included they should be non-ionic softeners. The bleaching and scouring operation removes waxes, pectins and foreign matter from the fabric and opens up the dye sites in order to maximize color pick up. [0029]
B. Prepare a dye gain print paste by the following process: [0030]
1. Thoroughly mix 15 parts water and 5 parts kerosene emulsifier and then slowly add 80 parts of mineral turpentine oil (MTO) or kerosene. Stir the mixture until a stable emulsified paste is formed. [0031]
2. Prepare a dye gain paste by thoroughly mixing 50 parts of cationic dye gain material and 50 parts of water. A suitable dye gain material is formulated by addition of acrylic copolymer, styrene monomers and acrylates. [0032]
3. Prepare the print paste by slowly adding 76 parts of dye gain paste to 24 parts of MTO/kerosene paste under constant stirring, and continuing stirring until a uniform homogeneous paste is formed. [0033]
C. Apply the dye gain print paste to the prepared for dyeing (PFD) fabric in accordance with a spatial pattern using a flatbed printing machine, as is conventional for screen printing fabric, or using a rotary printing machine, which is advantageous because it allows printing at a higher speed. The viscosity of the dye gain print paste can be reduced if necessary by addition of water. [0034]
The printed fabric is first dried at 80-90° C. and then heated to 130-135° C. for five minutes in order to cure the polymer of the dye gain material and bond it to the fabric. [0035]
D. Cut the fabric into garment pieces and make the garment pieces up into garment modules. Since the dye gain print paste is colorless, acrylic dye may be added to the print paste to impart a tint to the paste for ease of cutting. [0036]
E. Overdye the garment modules using anionic dyes. The cationic sites of the dye gain material attract the dye anions and consequently strong dye yields are observed at the areas to which the dye gain print paste has been applied. The areas to which the dye gain print paste has been applied pick up the dye with a deeper or more intense shade than other areas, thus providing a two-tone effect having areas of deeper color and areas of normal color. [0037]
The difference in shade between the areas that have received the dye gain print paste and the areas that have not received the dye gain print paste depends on the proportion of dye gain paste in the print paste. A lighter dye gain is achieved by mixing the dye gain paste and MTO/Kerosene paste in proportions 65:35 or 50:50 instead of 76:24. [0038]
The method described above allows much of the work in manufacture of a garment for sale to be carried out before the retailer specifies the color of the garment. The garment modules can be made in one location, far from the retailer, and delivered to an overdyeing facility closer to the retailer. Garment modules that have been prepared in the manner described above are resistant to normal atmospheric conditions for months. Consequently, they can remain in storage at the overdyeing facility for an extended period without deterioration. When a retailer places an order for a particular color, the required garment modules are overdyed, finished and packed for delivery. These final steps can be completed in a few days, allowing rapid response to changes in market demands. [0039]

EXAMPLE II

A second method in accordance with the invention is used to moderate the effect of overdye when applied to fabric. This second method involves five main operations: [0040]
A. Greige fabric is prepared for dyeing using the same process as in Example I. [0041]
B. A dye resist print paste is prepared by thoroughly mixing 99 parts dye resist polymer (by weight), one part (by weight) of catalyst, and pigment of a nature and in a proportion depending on the color and intensity desired. The dye resist polymer is an acrylic copolymer. In the event that it is desired that the dye resist paste be white, the pigment may be titanium dioxide; and in the event another color is desired, another suitable pigment is used. The paste is mixed thoroughly under continuous stirring. [0042]
C. Apply the dye resist print paste to the PFD fabric in accordance with a spatial pattern using a flatbed printing machine or a rotary printing machine, as described in Example I. The viscosity of the dye resist print paste can be reduced if necessary by addition of water. [0043]
The printed fabric is dried and cured as in the case of Example I. The catalyst promotes the reaction whereby the acrylic copolymer in the dye resist paste cross links with the fabric. [0044]
D. Cut the fabric into garment pieces and make the garment pieces up into garment modules, as described in connection with Example I. [0045]
E. Overdye the garment modules using anionic dyes. Preferably, the dyes are reactive or direct, as in the case of Example I. The dye resist print paste is highly anionic and therefore the areas of a garment module to which the print paste has not been applied pick up the overdye color while the areas to which the print paste has been applied do not but on the contrary retain the color imparted by the pigment included in the dye resist print paste. Consequently, the color of the garment module is not restricted to greater and lesser depths of the overdye color, and if the garment module is made up of pieces that have been printed using dye resist print pastes with different pigments, the various pieces of the garment module have the colors respectively associated with the pigments but are unified by the color of the overdye. [0046]
The method described in Example II has similar advantages to Example I with respect to choices of color and rapid repsonse to market demands. [0047]

EXAMPLE III

A third method in accordance with the invention is used to both intensify and moderate the effect of overdye on a cellulosic fabric in different respective areas. [0048]
This third method involves ** main operations: [0049]
A. Prepare greige fabric for dyeing by the process described in Example I. [0050]
B1. Prepare a dye gain paste in accordance with step B of Example I. [0051]
B2. Prepare a white or colored dye resist print paste in accordance with step B of Example II. [0052]
C. Apply the dye gain print paste to selected areas of the PFD fabric and apply the dye resist print paste to other areas of the PFD fabric at respective stations of a suitable printing machine, such as a rotary printing machine. The viscosity of the one or both print pastes can be reduced if necessary by addition of water. Dry the printed fabric and cure the polymer as described in Examples I and II. [0053]
D. Cut the fabric into garment pieces and make up the garment pieces into garment modules as described in Examples I and II. [0054]
E. Overdye the garments modules by the exhaust method using direct or reactive dyes. [0055]
The dye resist and dye gain agents are acrylic copolymers that are used in accordance with the present invention are synthesized with high value softeners to avoid peel off. Further, these new polymers are formulated on different monomer basis and cannot be felt by hand after printing and do not peel off after repeated washings. [0056]

EXAMPLE IV

A first batch of cotton yarn is treated on a package dye machine with a cationic polymer that renders the cotton yarn receptive to acid dyes. A suitable cationic polymer is polyamide epichlorhydrin. A second batch of cotton yarn is dyed in conventional manner by package dyeing and dried. Different packages in the second batch may be dyed with different colors. The dyed yarns of the second batch and the treated yarns of the first batch are knit or woven together to form a fabric and the fabric is scoured and finished in conventional fashion, without bleaching. The scouring process removes foreign matter, such as waxes and pectins, and thereby opens up the dye sites of the fabric and maximizes color pick-up. The fabric is then cut into garment pieces which are sewn to form a garment. At this point the garment is not ready for retail sale because the treated yarns have not been dyed. The garment is dyed using an acid dye that has an affinity for the cotton yarn that has been treated with the cationic polymer and will fix to the yarns of that cotton. However, because the acid dye has no affinity for the untreated cotton yarns the dye molecules will not fix to the cotton that has previously been dyed. Consequently, depending on the nature of the pattern in which the treated yarns and dyed yarns are knit or woven, the cotton garment has a colored pattern or the perceived color of the garment is a blend of the color of the dyed yarns and the color that is imparted to the treated yarns by the acid dye. [0057]
EXAMPLE V [0058]
Mercerizing is a form of chemical treatment that involves treatment with caustic soda. Mercerized cotton yarns have a greater affinity for certain dyes than nonmercerized cotton yarns. Conventionally, a fabric has been made either from all mercerized yarns or from all nonmercerized yarns. [0059]
In accordance with the invention, mercerized yarns and nonmercerized yarns are knit or woven together in the same fabric, which is then scoured. The fabric is compacted (in the case of knit fabric) or sanforized (in the case of woven fabric) to control shrinkage. Garment pieces are cut from the fabric and sewn together to form a garment module and the garment module is dyed using a dye that has differential affinity for mercerized and nonmercerized yarns, such as a reactive, direct or pigment dye. The different affinity for dye of mercerized yarns and nonmercerized yarns results in a visual difference between the mercerized and nonmercerized yarns. The visual difference is more prominent with light or medium dyes than with dark dyes, which may provide a tonal effect rather than a visually discernible color difference. [0060]

EXAMPLE VI

A first batch of cotton yarn is dyed and the dyed yarn is chemically treated with a dye resist agent and is processed in order to cure the agent. For example, a suitable dye resist agent is a reactive silicone. In this case, the dyed yarn is dipped in hank form into a solution of reactive silicone (such as the material sold by Britacell under the designation Microsil) and is placed in an infrared oven so that the silicone is cured and thereby bonded to the yarn. The silicone resists absorption of dye into the yarn fiber. Fabric is knit or woven using the treated yarns and untreated yarns that have not been dyed. The fabric is cut into garment pieces that are sewn together to form a garment module. The garment module is dyed. The untreated yarns take the color of the dye whereas the silicone prevents the treated yarns from taking the color of the dye. The treated yarns retain their original color, which was imparted prior to chemical treatment. Consequently, depending on the weaving or knitting pattern, it is possible to create multicolored strips or plaids that retain their true colors and do not look over-dyed. [0061]
The invention is not restricted to the dye resist agent being reactive silicone and other materials also are suitable. In addition, the invention is not restricted to the material that influences dye uptake being a material that prevents or reduces dye uptake, and a dye gain agent may be used instead. [0062]

EXAMPLE VII

The affinity of a yarn for a reactive or direct dye depends on the chemical composition of the yarn. In general, cotton yarns accept reactive and direct dyes whereas synthetic yarns do not accept reactive and direct dyes. [0063]
Synthetic yarn that has been fiber-dyed or yarn-dyed and cotton yarn that has not been dyed are woven or knit to create a fabric. The fabric is cut into garment pieces and the pieces are sewn together to form a garment module, and the garment module is dyed using a reactive or direct dye. The synthetic yarn is selected so that it does not accept the reactive or direct dye whereas the cotton yarn does, and accordingly the fabric combines the colors of the dyed cotton yarns and the fiber-dyed or yarn-dyed synthetic yarn. [0064]
The synthetic yarn may be a polyester yarn, a nylon yarn or an acrylic yarn, for example. Preferably, the synthetic yarn is spun polyester, which is made from staple lengths of polyester fiber that are spun into a yarn in similar fashion to that in which cotton yarn is made, and is similar in hand and appearance to cotton yarn. The resulting fabric has similar appearance and hand to a 100% cotton fabric. [0065]
Garment dyeing in the manner described above in Examples I-VII is particularly advantageous because it allows garment modules to be made in advance of the final determination of color. The garment modules can then be dyed and immediately shipped to retail stores without any intervening manufacturing steps, as would be necessitated in the case of a fabric dyeing process. This allows the retailer to respond rapidly to changes in demand in the marketplace. [0066]

EXAMPLE VIII

In a modification of Examples IV-VII, the fabric includes a yarn with a different affinity for the dye than the first and second yarns. For example, in the case of Example IV, the third yarn may be a polyester/cotton blend that has a smaller affinity for acid dyes than the untreated cotton yarn; or in the case of Example VII, the third yarn may be a solid base synthetic yarn such as acrylic yarn. [0067]

EXAMPLE IX

In garment dyeing, it has been found that improved performance is obtained if salt is added to the process bath after the dye has been added but before starting heating to the fixation temperature. Other chemicals (particularly alkali) are added to the process bath after the bath has been heated to the exhaustion temperature. It has been found that this results in better dye penetration at the seams of the garment, which is desirable in order to produce a quality garment-dyed product. [0068]
It will be appreciated that the invention is not restricted to the particular embodiments that have been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims and equivalents thereof. For example, although the invention has been described in connection with garment dyeing, which is preferred, certain aspects of the invention may also be applied to fabric dyeing. Of course, use of fabric dyeing will prevent achievement of the advantages that arise from use of garment dyeing. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated. [0069]

Claims

1. A method of creating a fabric with a colored pattern, comprising:

(a) providing at least first and second yarns, wherein the first yarn has a greater affinity than the second yarn for a selected dye,

(b) creating a fabric using at least the first and second yarns, and

(c) dyeing the fabric using the selected dye.

2. A method according to claim 1, comprising, between steps (b) and (c), making a garment from the fabric.

3. A method according to claim 1, wherein step (a) includes treating the first yarn with an agent that renders the first yarn receptive to an acid dye and step (c) includes dyeing the fabric with an acid dye.

4. A method according to claim 1, wherein the first yarn is a mercerized yarn and the second yarn is a nonmercerized yarn.

5. A method according to claim 1, wherein step (a) includes treating the second yarn with an agent that renders the second yarn resistant to uptake of the selected dye.

6. A method according to claim 1, wherein the first yarn is of a different type from the second yarn, such that the first yarn has a greater affinity for the selected dye than has the second yarn.

7. A method according to claim 6, first and second yarns are of different chemical composition.

8. A method according to claim 7, wherein the first yarn is a cellulosic yarn and the second yarn is a polyester yarn.

9. A method according to claim 1, wherein step (a) includes providing a third yarn having a smaller affinity for the selected dye than the second yarn and step (b) comprises creating a fabric using the first, second and third yarns.

10. A method according to claim 9, wherein the third yarn is a blend of cellulosic and non-cellulosic fibers.

11. A method according to claim 9, wherein the third yarn is a blend of cotton and polyester fibers.

12. A method according to claim 9, wherein the third yarn is a solid base synthetic fiber yarn.

13. A method of printing a fabric article formed from cellulosic fibers, comprising:

a) printing the article with a dye gain print paste including an acrylic copolymer, and

b) thereafter dyeing the article.

14. A method according to claim 13, wherein the dye gain print paste contains styrene monomers and acrylates.

15. A method according to claim 13, further comprising, between steps (a) and (b):

cutting the fabric article into garment pieces, and making up the garment pieces into garment modules, and wherein step (b) is a garment dyeing step.

16. A method of printing a fabric article formed from cellulosic fibers, comprising:

a) printing the article with a dye resist print paste including an acrylic copolymer, and

b) thereafter dyeing the article.

17. A method according to claim 16, further comprising, between steps (a) and (b):