Title of Invention

"A METHOD FOR IMPROVING DYEABILITY OF ACRYLIC FIBRE AND THE DYED PRODUCTS THEREOF

Abstract

A method of improving the dyeability of acrylic fibre and the dyed products thereof are disclosed. The said method comprises of two step reaction of the acrylic fibre, desired to be dyed. The first step comprises of partial conversion of acrylonitrile of acrylic fibre into said active group. The second step comprises of reaction of the modified acrylic fibre from said first step with said dye. The said first step consists of reaction of the said acrylic fibre with hydroxylamine hydrochloride or hydrazine at a controlled temperature and pH with constant stirring followed by washing and drying of the said acrylic fibre in air oven. The said modified acrylic fibre achieved from said first step is reacted with acid or reactive or disperse dyes in the said second step to get the said dyed products.

Full Text

The present invention relates to A Method for improving Dyeability of Acrylic Fibre and the Dyed Products thereof. FIELD OF INVENTION: Particularly, the present invention relates to a method of modification of the acrylic fibres, which are incapable of dyeing with acid or reactive or disperse dye, more particularly, to a method of partial conversion of acrylonitrile of acrylic fibre into an active amino group to make them suitable for dyeing with acid, reactive, disperse dyes, even more particularly to a method of partial conversion of acrylic fibre comprising acrylonitrile group into an acrylic fibre comprising of acrylonitrile group and an active amino group to make them suitable for dyeing with acid, reactive, disperse dyes and to a method of dyeing the said modified acrylic fibre and the dyed products thereof. BACKGROUND OF THE INVENTION: The dyeing of the polymeric fibre particularly the acrylic fibre is highly specific in nature due to the inherentcharacteristics of the acrylic fibre. The inherent characteristics of the acrylic fibre, such as low moisture absorption and dyeability are mainly due to the presence of the nitrile group, such as acrylonitrile groups. The compactness of the polymeric structure, particularly the acrylic fibre structure also adds to the specificity of the dyeing of the polymeric fibre, particularly the acrylic fibre. This compactness is again mainly due to the presence of nitriole groups such as acrylonitrile groups. The highly specificity of the dyeing process of the polymeric fibre as referred hereinabove means that such fibres have restricted dyeability with various classes of dyes like acid, reactive, and disperse dyes. The commercially available polymeric fibres particularly acrylic fibreshave up to 15% of the comonomer, particularly acrylic monomer, which makes them dyeable with the disperse dyes. However, this characteristic does not improve the dyeability of the polymeric fibres particularly of the acrylic fibres towards the reactive and acid dyes. Further, the dyeability towards the disperse dyes is also not improved to the satisfactory extent. Therefore the polymeric fibres, particularly acrylic fibres have poor or no dyeability towards the reactive, acid, and also disperse dyes. Further, the dyeing of the polymeric fibres particularly the acrylic fibres, as known in the prior art is carried out at high temperatures. The temperature of the dyeing process is close to the boiling temperature of water that is as high as 100°C. This requirement necessitates the consumption of high energy, which in turn makes the dyeing process economically unviable. Therefore any improvement or the modification of the acrylic fibres, which makes them dyeable with the known and commonly used dyes such as basic and disperse dyes and particularly enhances the dyeability of such fibres towards the disperse dyes in addition to making them dyeable towards the acid and reactive dyes will make the acrylic fibres suitable for dyeing with wide spectrum of available dyes. Further, if such process could be carried out at lower temperature, preferably at the room temperature will result in the energy saving and hence make the whole process economically viable and ecofriendly. Further, drawback of known method of improving the polymeric fibres is that the use of the agents to improve the said fibres results in the destruction of the morphological structure of the said fibresand some times in the change in colour of the fibres to the unwanted colour. However, as aresult of such methods the improvement of the dyeability characteristics of the said fibres is rarely observed to the satisfactory level. Therefore, there is a need to have a method of improving the dyeability of acrylic fibres and the dyed products thereof. Particularly, there is a need to have a method of modification of polymeric fibre particularly acrylic fibre, which are incapable of dyeing with acid, reactive, and disperse dyes, which can overcome the drawbacks of the prior art as described herein above. More particularly, the need is to have a method of partial conversion of acrylonitrile groups of acrylic fibres in to an active group, which in turn make them suitable for dyeing with acid, reactive, and disperse dyes and at the same time can enhance the dyeability of the acrylic fibres, particularly the acrylic fibres towards the commonly available acid, reactive, and disperse dyes and a method of dyeing the said modified acrylic fibres resulting into desired dyed products. OBJECTS OF THE INVENTION: This is the main object of the present invention is to propose a complete disclosure of a method of improving the dyeability of acrylic fibre and the dyed products thereof, which can overcome the disadvantages of the prior art as described herein above. Another object of the present invention to propose particularly for a method of modification of the acrylic fibre, which are incapable of dyeing with acid or reactive or disperse dyes, which can overcome the disadvantages of the prior art as described herein above. Further, the object of the present invention to propose for a method of partial conversion of acrylic fibre comprising of acrylonitrile group, which are responsible for poor or no dyeability of acrylic fibres as stated herein above into an acrylic fibre comprising of acrylonitrile group and active amino group to make them suitable for dyeing with acid or reactive or disperse dyes, which can be carried out at the room temperature. Still another object of the present invention is to propose a complete disclosure of the method of dyeing the modified acrylic fibres as achieved in the first step of this invention, which can also be carried out totally at the room temperature and the dyed products thereof. This is still another object of the present invention is to propose a complete disclosure of the method as stated herein above, wherein the morphological structure of the fibre is not destroyed and at the same time there is no change in colour of fibres to the unwanted colour. But the dyeability characteristics of the said fibres is improved to the desired extent. Yet another object of the present invention is to propose for a method as stated herein above, wherein the resulted modified acrylic fibre has the reduced compactness and enhanced moisture absorption capacity. BRIEF DESCRIPTION OF THE INVENTION: Accordingly, this invention provides a complete disclosure of a method of improving the dyeability of acrylic fibre and the dyed products thereof. Particularly, the present invention provides a method of modification of polymeric fibre particularly the acrylic fibres, which are incapable of dyeing with acid or reactive or disperse dyes, particularly with acid or reactive dyes. More particularly the invention provides a complete disclosure of a method of partial conversion of acrylic fibre comprising of acrylonitrile group and active group, which in turn make them suitable for dyeing with acid, reactive, disperse dyes and at the same time enhances the dyeabiility of the acrylic fibres towards the commonly available acid, reactive, and disperse dyes and in addition the resulted modified said fibre has reduced compactness and enhanced moisture absorption capacity. Further, accordingly this invention also provides a method of dyeing the said modified fibres particularly acrylic fibres, which in turn results in the desired dyed products. According to the most preferred embodiment of the presently disclosed invention the method comprises of two-step reaction of the polymeric particularly acrylic fibre desired to be dyed. DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION: According to the present invention a complete disclosure of a method of improving the dyeability of acrylic fibre through a method of modification of the acrylic fibre, which are otherwise incapable of dyeing with commonly available acid and reactive dyes is made and said method comprises of: two-step reaction of said fibre and (i) partial conversion of acrylonitrile group of acrylic fibre into an active amino group resulting into a modified fibre with enhanced dyeability, and (ii) reacting resulted modified fibre from first step with a dye in a known manner to get the dyed products wherein (a) the said conversion in step (i) is carried out by reacting with strong reducing agent containing amino group such as herein described, at room temperature, and (b) step (ii) is performed at temperature of 30 to 60°C. Accordingly the presently disclosed method results in the enhancement of dyeability of the acrylic fibres towards the commonly available acid and reactive dyes, and in addition the resulted modified fibre has reduced compactness and enhanced moisture absorption characteristics. According to one of the preferred embodiment of this invention, the first step consists of reaction of the said fibre with salt of hydroxylamine and this reaction is carried out at a controlled temperature and pH. This step is carried out with constant stirring, which is followed by washing and drying the said fibre in air oven. In accordance to another embodiment of this invention the first step consists of reacting the said fibre with hydrazine, preferably pure hydrazine. Such reaction is carried out at a controlled temperature and pH, preferably with constant stirring, which is followed by washing and drying the said fibre in air oven. In accordance to another embodiment of this invention as stated hereinabove, the acrylic fibre comprising of acrylonitrile group is partly converted into acrylic fibre comprising of acrylonitrile groupand active group during first step reaction of two steps reaction. In accordance to the preferred embodiment of the present invention the active group as referred herein above is amino group and the acrylonitrile group as referred herein above is -ON attached to -CH-CH. In accordance to one of the preferred embodiments of this invention the modified fibre as achieved from the first step is reacted with acid or reactive or disperse dye and the said reaction is carried out at a controlled temperature and pH during second step of the reaction. Such reaction is allowed for 1 to 4 hours preferably with constant stirring in the second step to get the said dyed products. The dyed products obtained after second step of two step reaction of the method of the present invention has good dyeability and wash fastness. The stirring bas referred herein above means the shaking or rotation of the reaction bath. In accordance to the preferred embodiment of the present invention the salt of hydroxylamine is preferably hydroxylamine hydrochloride more preferably it is the aqueous solution of hydroxylamine hydrochloride, even more preferably it is the 1 to 20% aqueous solution of the hydroxylamine hydrochloride still more preferably it is the 2 to 10% aqueous solution of the hydroxylamine hydrochloride. In accordance to another preferred embodiment of the present invention the pure hydrazine is preferably the aqueous solution of pure hydrazine, more preferably it is the 1 to 20 % aqueous solution of the pure hydrazine, more preferably it is the 2 to 10 % aqueous solution of the pure hydrazine. In accordance to the preferred embodiment of the present invention the ratio of the fibre and the aqueous solution of the salt of hydroxylamine or of hydrazine in the first step is maintained between 1:20 to 1:200, preferably between 1:40 to 1:80. The temperature in the first step is maintained between 30 to 60°C, preferably at the room temperature. The pH in the first step is maintained between 1 and 10, preferably between 4 and 8. The total time taken by the first step in accordance to the present invention is only 30 minutes to 6 hours, preferably between 30 minutes and 4 hours. The partial conversion of the acrylonitrile group of acrylic fibre into an active group varies between 2 and 80%, however, when the reaction is carried out under preferable conditions in accordance to the preferred embodiments of this invention the partial conversion varies only between 2 and 30%. In accordance to another preferred embodiment of the present invention, as stated herein above, the modified fibre achieved from the first step, as described herein above, is reacted with acid or reactive or disperse dye at controlled temperature of 30 to 60°C, preferably of 30 to 45°C and a pH between 1 and 8.5, preferably acidic pH for 1 to 4 hours, preferably for 1 to 2.5 hours with constant stirring in the second step to get the said dyed product. The acid or reactive or disperse dye as referred herein above is selected from the commonly available dyes. The present invention is however, not restricted by the selection of the particular dye, but the capability of the modified fibre to dye with the wide spectrum of dyes, preferably acid, reactive or disperse dyes with enhanced dyeability is the main advantage of this invention. In addition the dyed product obtained in accordance to the method of the present invention has good dyeability and wash fastness. The another advantage of the method, as described herein above is that the whole process of the modification of the fibre and dyeing modified fibre is carried out at room temperature, still resulting in the good dyeability of the polymeric fibre, particularly of acrylic fibre even with acid and reactive dyes including disperse dyes. WE CLAIM: 1. A method of improving the dyeability of acrylic fibre through a method of modification of a acrylic fibre, which are otherwise incapable of dyeing with commonly available acid and reactive dyes is made and said method comprises of: two-step reaction of said fibre and i. partial conversion of acrylonotrile group of acrylic fibre into an active amino group resulting into a modified fibre with enhanced dyeability, and ii. reacting resulted modified fibre from first step with a dye in a known manner to get the dyed products wherein (a) the said conversion in step (i) is carried out by reacting with strong reducing agent containing amino group such as herein described, at room temperature and (b) step (ii) is performed at temperature of 30 to 60°C. 2. A method as claimed in claim 1 wherein the strong organic reducing agent containing amino group used in step (i) is by hydroxylamine, or salt of hydroxyl amine, preferably hydroxyl amine hydrochloride, or hydrazine. 3. A method as claimed in any preceding claims wherein the conversion in step (i) is performed under constant stirring. 4. A method as claimed in any preceding claims wherein the conversion in step (i) is conducted using aqueous solution of the said strong organic reducing agent containing amino group. 5. A method as claimed in claim 4 wherein the aqueous solution used is 1 to 20% preferably 2 to 10 % by wt. 6. A method as claimed in any preceding claims wherein the ratio of fibre to hydroxyl amine hydrochloride, or hydrazine varies from 1:20 to 1:200, preferably 1: 40 to 1:80. 7. A method as claimed in any preceding claims wherein the modified fibre is subjected to washing, followed by drying in air, oven. 8. A method as claimed in any preceding claims wherein the partial conversion in step (i) varies from 2 to 80%, preferably 2 to 30%. 9. A method as claimed in any preceding claims wherein the reaction in step (i) is performed for a period of 0.5 to 4 hours preferably for 1 to 2.5 hours. 10. A method as claimed in any preceding claims wherein the reaction in step (ii) is performed for a period of 0.5 to 6 hours, preferably 0.5 to 4 hours. 11. A method as claimed in any preceding claims wherein the reaction in step (i) is performed at a pH between 1 and 10 preferably between 4 and 8. 12. A method as claimed in any preceding claims wherein the reaction in step (ii) is performed under acidic pH preferably between 4 and 8. 13. A dyed product obtained by a method as claimed in preceding claims. 14. A method of improving the dyeability of acrylic fibre substantially as herein described.

Documents:

1324-del-1997-abstract.pdf

1324-del-1997-claims.pdf

1324-del-1997-correspondence-others.pdf

1324-del-1997-correspondence-po.pdf

1324-del-1997-description (complete).pdf

1324-del-1997-form-1.pdf

1324-del-1997-form-13.pdf

1324-del-1997-form-19.pdf

1324-del-1997-form-2.pdf

1324-del-1997-form-26.pdf

1324-del-1997-form-5.pdf

1324-del-1997-form-6.pdf

1324-del-1997-gpa.pdf