A BLACK COLORANT FORMULATION FOR PREPARING THE SAME

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a complete application in pursuance of the Provisional Application No. 259/MUM/2013, filed on January 29 ^th 2013, titled "BLACK COLORED FIBER AND A BLACK COLORANT FORMULATION FOR PREPARING THE SAME"

FIELD OF INVENTION

[0002] The present invention is directed to a black coloredfiber. More particularly the present invention is directed to a black coloredfiber prepared by dope-dyeing using a black colorant formulation, wherein the black colorant formulationincludesa surface active agent, a steric stabilizer,an anti-coagulating agent, a defoamer, and an alkali.

BACKGROUND OF INVENTION

[0003] Demand for solid shades with evenness in dyeing, better light fastness, and deeper shades is seeing a constant increase. For example, black colored viscose fibers that are commercially available show a color value 'L'of about 14.13 units and a color strength 'K/S'of about 27.86 units. Various methods of dyeing have been tried to achieve the darker shades and have met with limited success. Dope-dyeing is one of the preferred modes of dyeing used to achieve these solid shades. Dope-dyeing of fibres has its advantages over other known dyeing processes. The total dye required to provide desired colour shade is relatively lower than that used in other known methods. Accordingly the amount of dye in the effluent is low resulting inareduced load on the environment. Further, in dope dyeing the dye enters into the compact structure of the fiber, for example, cellulose fiber, which results in low bleeding of dye from the fiber. Thus increasing the life of product by reducing the fading of the color in the fabric prepared using thisfiber. It is well known that dope or spun dyed yarns carry forward to subsequent process the same volume and desired elasticity which are built into them during texturing when compared to yarn-dyeing. The resultant fiber/fabric has a smooth surface feel.

[0004] However, the depth of shade of the solid color obtained in dope dyed fabric is typically lower than that achieved using piece-dyeing.Methods of increasing the depth of shade by increasing the dye-loading in the fibre results in deterioration in spinning performance and adversely affects fibre physical properties.

[0005] Thus, there is a need for animproved and cost-effective black coloredfiber having deeper shades than what is currently available in the industry. Accordingly there is a need for a black colorant formulation that will provide the deepercolor shades in fibers by employing the dope-dyeing technique. SUMMARY OF INVENTION

[0006] In one embodiment, is provided a black coloredfiber. The black coloredfiber has a lightness value 'L' in a range of from about 13.0 to about 9.0 and a color strength 'K/S' in a range of from about 22to about 50.

[0007] In another embodiment, is provided a black colored fiber. The black colored fiber is prepared by dope-dyeing using a black colorant formulation. The black colorant formulation includes carbon black, a surface active agent, a steric stabilizer, an anti- coagulating agent, a defoamer, and an alkali. The black colored fiber has a lightness value 'L' in a range of from about 13.0 to about 9.0and a color strength 'K/S' in a range of from about 22to about 50. [0O08] In yet anotherembodiment, is provided a black colorant formulation. The colorant formulation includes carbon black, a surface active agent, an anti-coagulating agent, a steric stabilizer,and a defoamer.The carbon black is present in an amount in a range of from about30 grams to about 42grams based on the total weight of the formulation.The surface active agent is present in an amount in a range of from about 2grams toabout 22gramsbased on the total weight of the formulation.The anti-coagulating agent is present in an amount in a range of from about 0.1 grams to about 1.5 gramsbased on the total weight of the formulation.The steric stabilizer is present in an amount in a range of from about0.5grams to about 2gramsbased on the total weight of the formulation.The defoaming agent is present in arange of from about 0.1 grams to about 13 gramsbased on the total weight of the formulation.The pH of the formulation is in a range of from about 8 to about 13. The carbon black, thesurface active agent,the anti-coagulating agent, the steric stabilizer, and the defoamerare dispersed in an aqueous media. The aqueous media is present in an amount in a range of from about 40 grams to about 60 gramsbased on the total weight of the formulation.

[0O09] In still yet another embodiment, is provided a black colorant pigment. The black colorant formulation described herein is then milled to obtain a black colorant pigment having an average particle size in the range of from about 60 nanometers to about 500 nanometers.

[0O10] In still yet another embodiment, is provided a black colored fiber-precursor. The black colored fiber-precursor includes the black colorant pigment described herein above and a polymer dope. The black colored fiber-precursor is spun to provide a black colored fiber.

[0O11] In still yet another embodiment, is provided a black colored fiber havinga black colored pigment entrapped in the fiber during processing.

[0O12] In still yet another embodiment, is provided a process for preparing a black colorant pigment.The process comprises a first step of mixing carbon black with a surface active agent, an anti-coagulating agent, a steric stabilizer, a defoamer, and water to form a black colorant formulation. The black colorant formulation is then milled to obtain a black colorantpigment having an average particle size in the range of from about60 nanometers to about 500nanometers.

[0013] By employing the above disclosed technique an improved black coloredfiber may be made possible. The above disclosed technique also aims to provide an improved, efficient, and cost effective black colorant formulation, black colorant pigment, and black colored fiber-precursor. BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 illustrates a visual representation of the dispersed state of the black colorant pigment prepared in accordance with the embodiments of the present invention in comparison to a PRIOR ART pigment. DETAILED DESCRIPTION

[0015] Embodiments of the invention as disclosed herein provide ablack coloredfiber. The invention also includes ablack colorant formulation. The black colorant formulation is then used to prepare a black colorant pigment. A black colored fiber-precursor is prepared using the black colorant pigment and a polymer dope. The black colored fiber-precursor is then employed to prepare the black coloredfiber. In addition to carbon black that imparts the black color, the black colorant formulation includes a surface active agent,an anti-coagulating agent, a steric stabilizer, and a defoamer, in an aqueous media with an alkaline pH. Advantageously the black colorant precursordisclosed herein hasan improved dispersibility and is accordingly capable of providing a fiber with a deeper shade of black(i.e., having a W lower 'L' value and a higher 'K/S value) than what is commercially available. As used herein the word "aqueous media" refers to water.

[0016] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. . The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0017] As used herein the terms first, second, third, etc... describe various elements or steps and these elements or steps should not be limited by these terms. These terms may be only used to distinguish one element or step from another element or step. Terms such as "first", "second", and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, first step discussed below could be termed a second step without departing from the teachings of the exemplary embodiments.

[001 8] Accordingly, in one embodiment, is provided a black colored fiber. The black colored fiber has a lightness value 'L' in a range of from about 13.0 to about 9.0 and a color strength 'K/S' in a range of from about 22 to about 50. The Lightness value measurements are based on a method available in literature called CIELAB and do not have any units.

[0019] In one embodiment, the black colored fiber is prepared by dope-dyeing using a black colorant formulation. The black colorant formulation includes carbon black, a surface active agent, a steric stabilizer, an anti-coagulating agent, a defoamer, and an alkali as described hereinabove.

[0020] One skilled in the art will appreciate that if the dye concentration exceeds about 13 weight percent based on about 9 weight percent of the fiber, for example, in case of cellulose fiber, then the fiber properties such as fiber denier, tensile strength, and surface feel may deteriorate. Accordingly the amount of carbon black employed may be determined by a person skilled in the art based on the fiber being dyed and the fiber forming process being employed. In one embodiment, as described herein, the amount of carbon black employed in the black colorant formulation is in a range of from about 30 grams to about 42 grams based on the total weight of the formulation. In another embodiment the amount of carbon black employed in the black colorant formulation is in a range of from about 32 grams to about 40 gramsbased on the total weight of the formulation. In yet another embodiment the amount of carbon black employed in the black colorant formulation is in a range of from about 35 grams to about 38 gramsbased on the total weight of the formulation.

[0021] The surface active agents used herein act as wetting agentsenabling improved dispersion of the contents that comprise the colorant formulation. In one embodiment, the surface active agent may include but are not limited to anionic, cationic, zwitterionie surface active agents with sulphate, sulphonate, carbonate and its alkaline and alkaline earth metal salts as head group and hydrogen tail Cg-C i 8 carbon. In one embodiment, the surface active agent includes the surface active agent is at least one non-ionic or anionic surface active agent selected from a group of non-ionic or anionic surface active agents consisting of alkyl phenoxy ethoxylated non-ionic surface active agents and ethoxylated alkyl alcohol surface active agents, polyethylene-block-poly propylene glycol-block -polyethylene glycol, and ethylenediamine tetrakis(propylene oxide-block-ethylene oxide) tetrol. Suitable examples of surface active agents include but are not limited to Disperlon 360, Usol K985, Tamol, BYK2012, BY 190, Disponill080, Disperlon AQ380, Lutensol XL, Aerosol OS, Aerosol C61, Auxi WET, AuxiDisp 100, Auxisil WHS, Aerosol GPG, SDBS, Galaxy LAO, Auxi Wet NP 100, Capstone FS 64, Wetting Agent FS 1010, Diosperlon AQ600, Disperlon AQ 800, Auxi Wet CRS, SM 8709, Dow Wetting Agent, and Bloomer.

[0022] In one embodiment, as described herein, the amount of surface active agent employed in the black colorant formulation is in a range of from about 2 grams to about 22 grams based on the total weight of the formulation. In another embodiment the amount of surface active agent employed in the black colorant formulation is in a range of from about 3 grams to about 20 gramsbased on the total weight of the formulation. In yet another embodiment the am^nt of surface active agent employed in the black colorant formulation is in a range of from about 5 grams to about 15 gramsbased on the total weight of the formulation.

[0023] , The anti-coagulating agent usedherein may assist in reducing the cohesive force between dispersedcarbon black particles. Suitable examples of anti-coagulating agent include but are not limited to polymers such as acrylates and phenolates more specifically polyacrylate co-polymers. In one embodiment, as described herein, the amount of anticoagulation agent employed in the black colorant fonnulation is in a range of from about 0.1 grams to about 1.5 grams based on the total weight of the formulation. In another embodiment the amount of anti-coagulation agent employed in the black colorant fonnulation is in a range of from about 0.2 grams to about 1.2 gramsbased on the total weight of the fonnulation. In yet another embodiment the amount of anti-coagulation agent employed in the black colorant fonmilation is in a range of from about 0.5 grams to about 1 grambased on the total weight of the formulation.

[0024] The defoamer(defoaming agent) used herein provides the reduced foaming in the fonnulation during milling. Suitable examples of defoamers include but are not limited W tosilicon based defoamers.In one embodiment, as described herein, the amount of defoaming agent employed in the black colorant formulation is in a range of from about 0.1 grams to about 13 grams based on the total weight of the formulation. In another embodiment the amount of defoaming agent employed in the black colorant formulation is in a range of from about 0.2 grams to about 12 gramsbased on the total weight of the formulation. In yet another embodiment the amount of defoaming agent employed in the black colorant formulation is in a range of from about 0.5 grams to about 10 gramsbased on the total weight of the formulation.

[0025] Steric stabilization is the process by which adsorbednonionic surfactantsor polyiners produce strong repulsion between particles and droplets in a dispersion. Suitable examples of steric stabilizers include but are not limited to diethylene glycol and polyethylene glycol. In one embodiment, as described herein, the amount of steric stabilizers employed in the black colorant formulation is in a range of from about 0.5 grams to about 2 grams based on the total weight of the formulation. In another embodiment the amount of steric stabilizers employed in the black colorant formulation is in a range of from about 0.6 grams to about 1.8 gramsbased on the total weight of the formulation. In yet another embodiment the amount of steric stabilizers employed in the black colorant formulation is in a range of from about 0.7 grams to about 1.5 gramsbased on the total weight of the formulation.

[0026] Stabilizing black colorant pigment in alkaline pH range of 8 to 13 helps to maintain the satiability of dispersion in cellulose dope. An alkali may be used to maintain the pH in a range of from about 8 to 13, for example, alkali and alkaline metal hydroxides.

[0027] In one embodiment, the carbon black, the surface active agent, the anti- coagulating agent, the steric stabilizer, and the defoamer may be dispersed in an aqueous media. In one embodiment, the aqueous media is present in an amount in a range of from about 40 grams to about 60 gramsbased on the total weight of the formulation. In another embodiment, the aqueous media is present in an amount in a range of from about 42 grams to about 58 gramsbased on the total weight of the formulation. In yet another embodiment, the aqueous media is present in an amount in a range of from about 45 grams to about 55 gramsbased on the total weight of the formulation.

[0028] In one embodiment, the black colorant pigment described herein has an average particle size in the range of from about 60 nanometers to about 500 nanometers. In another embodiment, the black colorant pigment described herein has an average particle size in the range of from about 70 nanometers to about 490 nanometers. In yet another embodiment, the black colorant pigment described herein has an average particle size in the range of from about 75nanometers to about 480 nanometers. Using a pigment having this particle size not only provides a smooth spinning without any pressure built-up in the fiber forming process but also provides uniform coloring in the resultant black colored fiber.

[0029] The black colored pigment may be obtained by processing the black colored formulation to obtain a particle size in the range of from about 60 nanometers to about 500 nanometers. In one embodiment, the black colored formulation may be subjected to a milling process to obtain the black colored pigment.

[0030] In still yet another embodiment, is provided a black colored fiber-precursor. The black colored fiber-precursor includes the black colorant pigment described herein above and a polymer dope. The black colored fiber-precursor is spun to provide a black colored fiber.

[0031] In one embodiment, the polymer dope may includecellulosic material such as viscose, rayon, and the like.

[0032] In stillyet another embodiment, is provided a black colored fiber having a black colored pigment entrapped in the fiber during processing. The entrapment of the fiber during processing is obtained by dope-dyeing as described herein. Advantageously, the black colored pigment and process employed herein result in a black colored fiber with smooth fiber surface, less use of dye pigment in process, high wash durability, and improved color fastness.

[0033] In still yet another embodiment, is provided a process for preparing a black colorant pigment. The process comprises a first step of mixing carbon black with a surface active agent, an anti-coagulating agent, a steric stabilizer, a defoamer, and water to form a black colorant formulation. The black colorant formulation is then milled to obtain a black colorant pigment having an average particle size in the range of from about 60 nanometers to about 500 nanometers.

EXAMPLES

Examples 1, 2 and 3 and Comparative Example 1 : Preparation of black color formulation:

[0034] Raw-material used in Examples 1 to 3 and in Comparative Example 1 are included in Table 1 below.

[0035] In all examples, the colorant composition was made using the following process. A formulation was made by charging asurface active agentauxiwet, sokalan FB-15, DEG,alkali, and carbon black with distilled mineral water to a one liter reactor. The resultant mixture was stirred for about lhour at a temperature of about 25 degrees Celsius using an overhead stirrerat a stirring speed of about 500revolutions per minute to form a black colorant formulation.

Example 4, 5, and 6 and Comparative Example 2: Preparation of black colorant Pigment [0036] The black colorant formulation prepared in Example 1 , 2, and 3were individually milled in a Retsch MM 200 mixer mill using steel balls beads for about four hours to reduce the maximum particle size to below 0.5 microns. The particle size was measured using Mastersizer 2000 and Zetasizer nano zs.The resultant black colorant pigment had a disperseability of about 60 nanometer to about 500nanometer(D90) in an aqueous media.

[0037] The black colorant pigment was made using various surface active agent systems at various process conditions. The black colorant pigment thus produced was subjected for settling analysis. The dispersibility of the black colorant pigment was observed by perfonxiing the settling analysis. A qualitative method in which the drop of blackcolorant pigment was added in 500 millilitres waterand settling behaviour of carbon black was observed for about 2 minutes to about 5 minutes. FIG. 1 illustrates a visual representation of the dispersed state of the black colorant pigment prepared in accordance with the embodiments of the present invention (Example 4) in comparison to a PRIOR ART pigment (Comparative Example 2). As shown in FIG. 1, it was observed that the black colorant pigmentprepared in accordance with the embodiments of the present invention was highly dispersed compared to the PRIOR ART pigment. Example 7, 8,and 9 and Comparative Example 3: Preparation of black colored fiber-precursor and black colored fiber.

[0038] Rawmaterial used in Examples 7, 8, and 9and Comparative Example 3 are included in Table 2 below.

TABLE 2

[0039] The black colorantpigment prepared in Example 4, 5, and 6 were independently mixed with the viscose dopeindicated in Table 2 at 1 OOOrevolutions per minute to form black colored fiber-precursor in Examples 7, 8, and 9 respectively. The resultant black colored fiber-precursor was individually spun through a spinneret 65 micron 40 holes, at aspinning rate of about 2.5 millilitres per minute to get a blackcoloredcellulosefiber.The black colored cellulose fiber was then first washed with hot water at 90 degrees Celsius for 5 minutes. The water wash was followed by an acid wash at 90 degrees Celsius using 17grams per liter aqueous sulphuric acid for 5 minutes followed by an alkali wash using 0.2 grams per liter aqueous sodium hydroxide solution at 90 degrees Celsius for 5 minutes. The color strength of the black coloredfiber was measuredusing X-rite colour spectrophotometer. The absolute color values obtained are described in Table 3 below.

Table 3 : Fiber color values L= lightness, a= red green axis, b= yellow blue axis, c= chroma, h=hue angle, K/S= color strength.

[0040] The black coloured fiber prepared in Example 7, 8, and 9 were also characterized using the scanning electron microscopy (SEM). As shown in Table 3, the K/S values for Examples 7 to 9 is greater than that for the comparative sample of black fiber.

[0041] The foregoing embodiments meet the overall objectives of this disclosure as summarized above. However, it will be clearly understood by those skilled in the art that the foregoing description has been made in terms only of the most preferred specific embodiments. Therefore, many other changes and modifications clearly and easily can be made that are also useful improvements and definitely outside the existing art without departing from the scope of the present disclosure, indeed which remain within its very broad overall scope, and which disclosure is to be defined over the existing art by the appended claims.