Composition and method for textile finishing

Abstract

The present invention relates to an aqueous textile finishing composition and method for treating fabrics such as silk, cotton, polyester, and blends thereof. The composition comprises a sulphonated polyester-type polymer in an aqueous medium, optionally with additives such as surface-active agents, preservatives, and fragrances. When applied by conventional finishing techniques, the composition forms a transparent, uniform film that imparts durable stiffness, enhanced pleat retention, and retained luster and softness. The formulation is shelf-stable, non-yellowing, resistant to microbial growth, and free from formaldehyde-releasing agents, providing an economical and fabric-friendly solution suitable for saree finishing and other textile applications.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of textile treatment, and more specifically to compositions and methods for finishing fabrics to impart stiffness, body, and luster.BACKGROUND

[0002] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Traditional saree finishing is often carried out using starch-based agents such as corn flour, maida, or sabu dana (sago) liquid. While such materials provide temporary stiffness, they are associated with several disadvantages, including lengthy preparation times, very short shelf life, susceptibility to fungal growth, development of unpleasant odor, and risk of fabric staining. Furthermore, starch finishes exhibit poor performance during humid monsoon conditions and quickly lose stiffness and luster after the first wash.

[0004] A number of other technologies have been explored for imparting stiffness, body, and luster to fabrics. Native and modified starches derived from tapioca, maize, rice, or wheat are inexpensive and commonly used but suffer from hygroscopicity, poor durability, microbial degradation, patchy film formation, and a tendency to yellow delicate fabrics such as silk. Synthetic polymer finishes such as polyvinyl alcohol (PVA) and polyvinyl acetate (PVAc) emulsions offer improved wash durability and better film integrity compared to starch. However, they form semi-transparent coatings that reduce the brilliance of zari, silk, or polyester yarns, impart a harsh handle, and add to costs, making them less suitable for low-cost sarees.

[0005] Other finishing agents include carboxymethyl cellulose (CMC) and natural gums such as tamarind kernel powder and guar gum. Although considered more eco-friendly, these agents provide inconsistent results due to variable raw material quality, exhibit low wash resistance, and suffer from poor stability in aqueous formulations. Crosslinking resins such as urea-formaldehyde and melamine-formaldehyde are also used to impart durable stiffness and wrinkle resistance. However, their use is restricted due to formaldehyde release, which raises environmental and health concerns, in addition to problems of yellowing and loss of natural sheen on delicate fabrics.

[0006] Overall, existing technologies for saree finishing remain inadequate. They are limited by short shelf life, microbial instability, inconsistent quality, lack of durability after washing, and negative effects on fabric aesthetics such as yellowing, dullness, or harsh handle. Moreover, some options carry high processing costs or face regulatory restrictions, particularly those involving formaldehyde-based resins. Thus, there is a pressing need for an improved finishing composition and method that provide durable stiffness and enhanced luster, while being fabric-friendly, stable in storage, cost-effective, and suitable for both traditional and modern saree finishing practices.OBJECTS

[0007] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0008] It is also an object of the present invention to provide a textile finishing composition that imparts durable stiffness, body, and luster to sarees and other fabrics.

[0009] Another object of the present invention is to provide a finishing composition having improved shelf life and resistance to microbial growth during storage and application.

[0010] A further object of the present invention is to provide a textile finishing method that yields consistent and reproducible results across different batches and fabric types.

[0011] A still further object of the present invention is to provide a finishing system that maintains stiffness and shine even under humid conditions and after multiple washing cycles.

[0012] Yet another object of the present invention is to provide an economical and fabric-friendly alternative to starches, gums, and formaldehyde-based resins, suitable for use in both industrial and traditional saree finishing practices.SUMMARY

[0013] The present invention provides an aqueous textile finishing composition and method for imparting controlled stiffness, body, and improved pleat retention to fabrics such as silk, cotton, and cotton-silk blends. The composition comprises a sulphonated polyester-type polymer, for example sulphonated polyethylene terephthalate (PET), dispersed in an aqueous medium. The polymer is a water-dispersible, film-forming material that creates a uniform and transparent coating on fabric surfaces. The composition may further include one or more formulation additives such as surface-active agents, preservatives, fragrances, and softeners to enhance processability, storage stability, and tactile properties.

[0014] The finishing composition can be applied using conventional textile processing techniques such as padding, spraying, or roll-polishing, followed by drying and controlled heating where necessary. Upon application, the formulation imparts a combination of stiffness, luster, and softness, while preserving the natural sheen and color of the fabric. Unlike conventional starch-based or PVA finishes, the present invention provides a wash-durable, non-yellowing, and humidity-resistant finish that remains effective after multiple laundering cycles.

[0015] The invention thus addresses longstanding limitations of traditional finishing agents by offering a shelf-stable, odour-free, and environmentally safer composition that is free from formaldehyde-releasing resins. The system provides consistent and reproducible finishing results across different saree types, enhances fabric durability, and improves commercial value. In addition, the formulation is designed for easy adoption by both industrial finishing units and small-scale textile processors without the need for specialized equipment, thereby ensuring wide applicability.

[0016] Accordingly, the present invention provides a durable, uniform, safe, and cost-effective finishing solution tailored to both premium silk sarees and mass-market cotton blends, achieving a balance of stiffness and retained softness / luster not attainable with prior art starch or PVA-based systems.

[0017] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0019] FIG. 1 illustrates a process flow diagram of an exemplary method for finishing a textile fabric using the aqueous finishing composition of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0020] The following is a detailed description of embodiments of the present invention. The embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

[0021] The present invention provides an aqueous textile finishing composition designed to impart controlled stiffness, body, and pleat retention to fabrics such as silk, cotton, polyester, and their blends, including cotton-silk sarees. The composition is based on a sulphonated polyester-type polymer, for example sulphonated polyethylene terephthalate (PET), which is water-dispersible and film-forming. Upon application to a fabric surface, the polymer forms a uniform, transparent film that provides durable stiffness, enhanced luster, and a soft hand feel. Unlike conventional starch- or PVA-based finishing agents, the composition disclosed herein is wash-durable, non-yellowing, resistant to humidity, and odor-free. The aqueous formulation exhibits excellent shelf stability and can be applied using standard textile finishing techniques, including padding, spraying, roll polishing, or combinations thereof. The system is particularly advantageous for saree finishing, as it maintains both stiffness and sheen even after multiple washes, while preserving the brilliance of delicate yarns such as silk and zari. The finishing composition may further include formulation additives such as surface-active agents, preservatives, fragrances, and softeners to improve stability, processability, and overall fabric aesthetics. The composition can be processed and applied under ambient conditions without the need for sophisticated machinery, making it suitable for both small-scale traditional finishing units and industrial textile processors. Accordingly, the present invention provides a safe, cost-effective, and fabric-friendly solution for durable textile finishing, offering consistent performance across various fabric types while overcoming key limitations of starch, gums, synthetic polymers, and formaldehyde-based resins.

[0022] In one embodiment, the invention provides a textile finishing composition comprising a sulphonated polyester dispersed in an aqueous medium. The sulphonated polyester functions as a water-dispersible, film-forming polymer, which provides the primary stiffening effect by forming a continuous and transparent coating on textile fibers. This coating imparts uniform stiffness, enhances pleat retention, and preserves the natural luster and sheen of delicate fabrics. The aqueous medium acts as the primary carrier, ensuring solubility and enabling ease of application using conventional finishing processes such as padding, spraying, or roll polishing.

[0023] In certain embodiments, the sulphonated polyester is sulphonated polyethylene terephthalate (PET). Sulphonated PET is highly suitable for textile finishing because it is inherently water-dispersible, easily incorporated into aqueous formulations, and capable of producing durable and transparent polymeric films. These properties enable the treated fabric to maintain both stiffness and brightness without yellowing or dulling the fabric surface.

[0024] In one embodiment, the sulphonated polyester is present in the textile finishing composition in an amount ranging from about 5% to about 30% by weight of the total composition. Within this range, several narrower sub-ranges may be employed depending on the desired balance of stiffness, durability, and softness. For example, the sulphonated polyester may be present in an amount ranging from about 8% to about 25%, about 10% to about 22%, or more preferably from about 15% to about 18% by weight of the composition. In certain embodiments, the sulphonated polyester is present in an amount of at least about 5%, at least about 8%, at least about 10%, at least about 12%, or at least about 15% by weight. In other embodiments, the sulphonated polyester is present in an amount of up to about 30%, up to about 28%, up to about 25%, up to about 22%, or up to about 20% by weight of the composition. In some representative formulations, the sulphonated polyester may be employed in specific amounts such as 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, or 30% by weight. These values provide flexibility for tailoring the stiffness and hand-feel properties of the finished textile. Amounts below about 5% typically fail to impart adequate stiffness or pleat retention, while amounts above about 30% may result in excessive rigidity or harsh hand feel. The range of 5-30% has been found to provide an optimal balance between durable stiffness, fabric luster, and softness.

[0025] In some embodiments, the composition further comprises a surface-active agent in an amount ranging from 0.5% to 5% by weight. The surface-active agent reduces surface tension of the aqueous medium and promotes homogeneous distribution of the polymer over the fabric surface. This prevents local aggregation or patchy film formation and ensures uniform stiffness and smoothness across the entire fabric. Suitable surface-active agents include anionic, cationic, non-ionic, and amphoteric surfactants, or mixtures thereof, selected to be compatible with the polymer and the aqueous formulation.

[0026] Examples of anionic surfactants include sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium stearate, sodium alkyl ether sulfates, and linear alkylbenzene sulfonates. These agents provide effective wetting and foaming properties, which facilitate uniform penetration of the aqueous composition into fabric fibers.

[0027] Examples of cationic surfactants include cetyltrimethylammonium bromide (CTAB), benzalkonium chloride, stearamidopropyl dimethylamine, and other quaternary ammonium salts. Cationic surfactants are particularly useful for imparting antistatic properties and can interact favorably with negatively charged fibers.

[0028] Examples of non-ionic surfactants include fatty alcohol ethoxylates, alkylphenol ethoxylates, sorbitan esters (such as Span surfactants), polysorbates (such as Tween surfactants), polyethylene glycol esters, and polyoxyethylene alkyl ethers. These surfactants are valued for their compatibility with a wide range of polymers and their low sensitivity to water hardness.

[0029] Examples of amphoteric surfactants include cocamidopropyl betaine, lauryldimethylamine oxide, and alkyl imidazolinium derivatives. Amphoteric surfactants can act as either cationic or anionic species depending on the pH, thereby providing versatile compatibility and mildness for delicate fibers such as silk.

[0030] The surfactant may be used individually or in combination with other surfactants to achieve the desired balance of wetting, dispersion stability, and film smoothness. The amount of surface-active agent is typically optimized such that the finishing composition spreads uniformly across the fabric while avoiding excessive foaming or residue.

[0031] In some embodiments, the composition comprises a surface-active agent in an amount ranging from 0.8% to 4% by weight, from 0.8% to 3% by weight, from 0.8% to 2.5% by weight, from 0.8% to 2% by weight, from 1% to 3% by weight, from 1% to 2.5% by weight, from 1% to 2% by weight, or 2% by weight.

[0032] The composition may also comprise a preservative in an amount ranging from 0.01% to 0.5% by weight, from 0.01% to 0.4% by weight, from 0.01% to 0.3% by weight, from 0.01% to 0.2% by weight, from 0.05% to 0.3% by weight, from 0.05% to 0.2% by weight, or from 0.1% to 0.2% by weight. The preservative functions to inhibit microbial growth in the aqueous medium, thereby preventing spoilage, odor development, and loss of performance during storage. The inclusion of a preservative ensures that the formulation remains stable and microbiologically safe for extended periods, typically from 6 to 18 months under ambient conditions. Suitable preservatives may be selected from parabens such as methylparaben, ethylparaben, propylparaben, and butylparaben; isothiazolinones such as methylisothiazolinone (MIT), chloromethylisothiazolinone (CMIT), and benzisothiazolinone (BIT); organic acid salts such as sodium benzoate, potassium sorbate, and calcium propionate; alcohol-based preservatives such as phenoxyethanol and benzyl alcohol; and other agents such as DMDM hydantoin or iodopropynyl butylcarbamate (IPBC). The preservative is selected to be compatible with the sulphonated polyester dispersion, non-reactive with other additives such as fragrances and softeners, and compliant with applicable textile safety standards.

[0033] In some embodiments, the composition may include a fragrance in an amount ranging from 0.01% to 1% by weight, from 0.01% to 0.8% by weight, from 0.01% to 0.6% by weight, from 0.01% to 0.5% by weight, from 0.05% to 0.5% by weight, from 0.05% to 0.3% by weight, or from 0.1% to 0.2% by weight. The fragrance enhances user acceptance by imparting a mild, pleasant, and long-lasting scent to the finished fabric. To prevent premature volatilization or interaction with other formulation components, the fragrance may be encapsulated, microencapsulated, or otherwise stabilized, thereby allowing controlled release and retention of scent even after several washes. Suitable fragrances include natural essential oils such as lavender, rose, jasmine, sandalwood, lemongrass, and orange oil; aroma aldehydes and ketones such as citral, cinnamaldehyde, vanillin, coumarin, ionone, and damascone; esters and lactones such as benzyl acetate, linalyl acetate, and γ-decalactone; and synthetic fragrance compounds such as musk ketone, galaxolide, or hexyl cinnamal. The fragrance component is incorporated at levels low enough to avoid interference with fabric stiffness, luster, or color stability, while ensuring a subtle and appealing sensory effect.

[0034] In some embodiments, the composition includes a softener in an amount ranging from 0.1% to 1% by weight, from 0.1% to 0.8% by weight, from 0.1% to 0.6% by weight, from 0.1% to 0.5% by weight, from 0.5% to 0.3% by weight, from 0.5% to 1% by weight, or from 0.6% to 1% by weight. The softener functions to balance the stiffness imparted by the film-forming polymer with a desirable hand feel, ensuring that the finished fabric does not become harsh. Suitable softeners include silicone emulsions, fatty acid condensates, and mixtures thereof. The combination of the polymeric film with a controlled level of softener allows the fabric to retain crispness and body while maintaining surface softness.

[0035] In some embodiments, provided is a textile finishing composition comprising 5-30% by weight of a sulphonated polyester, 0.5-5% by weight of a surface-active agent, 0.01-0.5% by weight of a preservative, 0.01-1% by weight of a fragrance, and water as the balance to 100%. This formulation provides a versatile finishing system suitable for use across different textile substrates.

[0036] In a particular embodiment, the composition comprises about 18% by weight of sulphonated polyester, 2% by weight of a surface-active agent, 0.1% by weight of a preservative, 0.1% by weight of a fragrance, and the remainder water (approximately 79.8% by weight). This formulation has been demonstrated to produce durable and uniform stiffness, enhanced pleat retention, and wash-fast shine on silk and cotton-silk blend sarees.

[0037] In various embodiments, the finishing composition is configured to impart both stiffness and retained luster / softness when applied to a textile fabric. This combination of properties is unique compared to conventional starch or polyvinyl alcohol (PVA) systems, which either fail to deliver durability or produce an undesirable harsh handle. The invention thus provides a finishing solution that enhances both the visual and tactile qualities of the fabric.

[0038] The invention further provides a method of finishing textile fabrics using the composition as described above. In one embodiment, the method comprises securing a textile fabric under tensile stress between a fixed end and an extended end, uniformly applying the finishing composition by means of a pneumatic or atomizing spray device, rolling the fabric on a cylindrical support member immediately after application, and subjecting the rolled fabric to controlled heating in a finishing chamber. The cylindrical support member may be a wooden or polymeric beam adapted for winding of the textile fabric. Heating is preferably performed at a temperature between 50 °C and 80 °C, which is sufficient to ensure water evaporation and film formation without adversely affecting delicate fibers such as silk. The method is particularly suited for finishing sarees and other woven textile articles, where it imparts enhanced stiffness, controlled drape, and wash durability while preserving softness and natural sheen.

[0039] FIG. 1 illustrates a process flow diagram of an exemplary method for finishing a textile fabric using the aqueous finishing composition of the present invention.

[0040] While the foregoing description discloses various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope of the invention. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.EXAMPLES

[0041] The present invention is further explained in the form of following examples. However, it is to be understood that the following examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.Example 1: Preparation of aqueous textile finishing composition

[0042] An aqueous textile finishing composition was prepared using the following method.1. Water charge: Deionized water was charged into a stainless-steel mixing vessel equipped with a mechanical stirrer. The water was maintained at ambient temperature of 20-40 °C.2. Addition of surface-active agent: A surface-active agent (2% by weight of the total composition) was added to the water with moderate agitation. Mixing was continued for 10 minutes until the surfactant was completely dispersed / dissolved and a homogeneous solution was obtained.3. Addition of preservative: A preservative (0.1% by weight) was added to the mixture, followed by stirring for an additional 5 minutes.4. Addition of fragrance: A fragrance component (0.1% by weight) was then added and stirred into the mixture for another 5 minutes until evenly dispersed.5. Addition of sulphonated polyester polymer: Sulphonated polyethylene terephthalate (PET) was slowly added under continuous stirring to reach a concentration of 18% by weight of the total composition. Care was taken to add the polymer gradually to avoid lump formation. During addition, the temperature was maintained at 20-40 °C. For more viscous grades of the polymer, high-shear mixing was employed to ensure uniform dispersion.6. Filtration and degassing (optional): The resulting dispersion was optionally passed through a 100-200 mesh filter to remove tramp particles and then subjected to mild vacuum degassing to eliminate entrapped air bubbles.7. Quality checks: The final composition was analyzed for total solids content, viscosity, and pH to confirm conformity with specifications.8. Packaging: The aqueous composition was filled into sealed high-density polyethylene (HDPE) drums for storage and further use.The composition was stable during storage and provided a homogeneous, transparent dispersion suitable for direct use in textile finishing applications.Example 2: Preparation of concentrated dispersion

[0043] Following the same procedure as Example 1, an aqueous textile finishing composition was prepared except that the sulphonated polyester polymer was added to a level of 25% by weight of the total composition. The composition exhibited higher viscosity but remained stable after filtration and degassing. Such concentrated dispersions may be diluted on-site prior to application, allowing greater flexibility in industrial processing.Example 3: Preparation of low-additive formulation

[0044] The composition was prepared according to the procedure of Example 1 except that the fragrance component was omitted and the surface-active agent was used at 1% by weight. The resulting formulation demonstrated equivalent polymer film formation and stiffness but without any olfactory effect on the fabric.Example 4: Application of composition by spraying (preferred for sarees)

[0045] An aqueous textile finishing composition prepared as described in Example 1 was diluted with deionized water in a ratio of 1:3 (composition to water). The dilution ratio was adjusted in the range of 1:2 to 1:5 depending on the stiffness desired for the finished fabric.The diluted composition was transferred into a pneumatic spray gun and uniformly applied to silk sarees under ambient conditions. After application, the sarees were subjected to natural air drying at 30-35 °C. Alternatively, drying was carried out in a controlled hot room at a temperature of 40-60 °C. For silk sarees, the drying temperature was maintained below 100 °C (preferably 80-90 °C) to avoid thermal damage to the fibers.Following drying, fixation of the polymeric film was achieved by roll polishing or calendaring at 120-160 °C for a short dwell time. For silk sarees, a milder fixation was employed, such as pressing or steam rolling at 100-130 °C for a short dwell time. The treated sarees exhibited enhanced stiffness, improved pleat retention, and retained luster without any yellowing or harsh feel.Example 5: Application of composition by padding

[0046] A working bath was prepared by diluting the aqueous finishing composition of Example 1 to a concentration of 70 g / L (within the range of 50-100 g / L). The working bath pH was adjusted to neutral (pH 6.5-7.0), within the acceptable range of 5-8. The viscosity of the working bath was measured at approximately 25 seconds in a Ford cup #4, corresponding to 50-60 cPs.Cotton-silk blend sarees were immersed in the working bath and passed through a padding mangle to achieve 75% wet pick-up (within the preferred range of 70-85%). The padded sarees were dried in a stenter frame at 110 °C until moisture was removed. For silk sarees, drying was performed at a lower temperature of 80-100 °C.Fixation was then carried out by roll polishing at 130 °C for a short dwell time. For silk sarees, fixation was performed by steam rolling at 110 °C. The resulting finished fabrics exhibited durable stiffness and gloss, which remained intact after repeated laundering.Example 6: Comparative application

[0047] For comparison, a silk saree was finished using a starch-based sizing solution prepared from sago at a concentration equivalent to 70 g / L solids. The saree exhibited initial stiffness but lost body and gloss after the first wash and developed a musty odor upon storage for three days under humid conditions. In contrast, the sarees treated with the sulphonated polyester composition of Examples 4 and 5 maintained stiffness, luster, and odor-free freshness even after five wash cycles.

Claims

1. A textile finishing composition comprising a sulphonated polyester dispersed in an aqueous medium.

2. The composition as claimed in claim 1, wherein the sulphonated polyester is sulphonated polyethylene terephthalate (PET).

3. The composition as claimed in claim 1, wherein the sulphonated polyester is present in an amount ranging from 5% to 30% by weight of the composition.

4. The composition as claimed in claim 1, further comprising a surface-active agent in an amount ranging from 0.5% to 5% by weight of the composition.

5. The composition as claimed in claim 1, further comprising a preservative in an amount ranging from 0.01% to 0.5% by weight of the composition.

6. The composition as claimed in claim 1, further comprising a fragrance in an amount ranging from 0.01% to 1% by weight of the composition.

7. The composition as claimed in claim 1, further comprising a softener in an amount ranging from 0.1% to 1% by weight of the composition.

8. The composition as claimed in claim 4, 5, 6, or 7, wherein the surface-active agent is selected from the group consisting of anionic surfactants, cationic surfactants, non-ionic surfactants, amphoteric surfactants, and mixtures thereof; or wherein the preservative is selected from the group consisting of parabens, isothiazolinones, benzoates, sorbates, phenoxyethanol, and mixtures thereof; or wherein the fragrance is selected from the group consisting of natural essential oils, synthetic aroma compounds, and mixtures thereof; or wherein the softener is selected from silicone emulsions, fatty acid condensates, and mixtures thereof.

9. A textile finishing composition comprising: a sulphonated polyester in an amount of 5-30% by weight of the composition; a surface-active agent in an amount of 0.5-5% by weight of the composition; a preservative in an amount of 0.01-0.5% by weight of the composition; a fragrance in an amount of 0.01-1% by weight of the composition; and an aqueous medium as balance to 100%.

10. A method of finishing a textile fabric, comprising the steps of: securing a textile fabric under tensile stress between a fixed end and an extended end; applying the composition as claimed in any preceding claim uniformly to the textile fabric using a pneumatic or atomizing spray device; rolling the textile fabric on a cylindrical support member immediately after application; and subjecting the rolled textile fabric to controlled heating in a finishing chamber, wherein the textile fabric after treatment exhibits enhanced stiffness and drape while maintaining softness.

11. The method as claimed in claim 10, wherein the cylindrical support member is a wooden or polymeric beam adapted for winding of the textile fabric.

12. The method as claimed in claim 10, wherein the finishing chamber is maintained at a temperature between 50 °C and 80 °C.

13. The method as claimed in claim 10, wherein the textile fabric is a saree or a woven textile article.