Technical Field

The invention is concerned with the dyeing of nylon fabrics with reactive dyestuffs in the presence of metallic mordant and bio-mordant salts in order to prevent any discolouration during usage in the textile industry and altering of the colours after washing, perspiration, during ironing or usage under the light.

Prior Art

Nylon fabric, also known as polyamide fabric, is included in the category of synthetic fabrics and is produced out of melted liquids after combining certain chemical substances under high heat pressure. It is a popular fabric used extensively among synthetic fabrics in the art. The first synthetic fibre produced in the world is nylon (polyamide) fibre. Nylon fibres that are most commonly preferred are nylon 6,6 and nylon 6.

Contrary to all other dyestuffs, reactive dyestuffs are able to react with fibre macro molecules and bond with the fibres through true covalent bonds. Similar to direct dyestuffs, they are anionic dyestuffs that greatly dissolve in water. Technically they are the most commonly used type of dyestuffs used for the dyeing of cotton products that can provide the required fastness sufficiently. Its wide colour palette with its bright colours is a simplified dyeing method that can be applied to dark colours, excellent wet fastnesses and normal dyeing devices. There are four groups in a reactive dyestuff and these are as follows;

Water-solubilizing group (S): This group ensures that the dyestuff is dissolved in water. Chromophore group (Chromogen) (C): Group that provides colours to the dyestuff molecule.

Bridge group (Section carrying the reactive group) (B): These are groups such as -NH, -CO, -SO2 that bind the coloured group of the molecule with the reactive group.

Reactive group (R): Is the group that forms covalent bonds with the functional group of the fibre. It creates the covalent bond between the fibre and dyestuff by reacting with the fibre. For dyed and ready-to-use textile materials and especially for those to be used for clothing purposes, it is expected to not encounter any colour alterations during the usage period and that the colours do not change after washing, perspiration, or during ironing and usage under the light. In the Technical dyeing applications, nylon fabrics are often dyed with acidic dyestuff and the dyeing temperature can reach 120“C. The range pH 5 to 7 is often preferred as dyeing pH. Other dyestuffs utilized for the dyeing of nylon fabrics are 1 :2 metal-complex and reactive dyes and there are experimental works and industrial dyeing works conducted with such dyestuffs. However, the functional groups of the reactive dyestuff used for these studies are different. Other dyestuffs used on nylon fibres, except for acidic dyestuffs, are not able to completely provide the washing, perspiration, ironing and light fastnesses expected from dyed products.

Mordants are metallic salts that ensure some dyestuffs to be bonded to fibres and describe colour fixatives used for dyeing works. In the field of fabric dyeing, these are auxiliary substances utilized as colour fixatives that ensure the colours are bonded with the fibres without any fading and are often used to achieve different colours. The process conducted with mordants prior, after or during dyeing in order to ensure that some dyestuffs are bonded with the fibres, is called mordanting. In order to achieve better dye adherence, the fibre or fabrics are first submerged into the mordant solution and then into the dyeing solution. The process of mordanting is conducted with natural or synthetic mordant chemicals and the purpose of using mordants is to ensure that molecules adhere to their places by enlarging the molecules on the fibre surface or inside the fibre and making them insoluble in water.

With the opinion that it is not possible to achieve sufficient fastnesses by dyeing nylon fabrics with acidic dyestuffs, it is aimed to prevent the water solubility of the dyestuffs of the fibre and thus achieve improvements in wet fastnesses (washing, water, perspiration, etc.) by generally processing the nylon fabrics in aqueous and acidic solutions together with synthetic mordant chemicals called syntans or tannic acids depending on the properties of the acidic dyestuffs utilized for dyeing upon completion of the dyeing process. Such processes do not always provide successful results, it is possible to change alterations of the colour of the resulting material and the improvements in the fastness values are limited. With dyeing nylon fabrics with reactive dyestuffs, it is possible to encounter different regularity, colour procurement and similar fastness problems.

As a result of the research conducted on this topic, the below-given applications are identified in the literature:

The patent document numbered TR2019/04848 is concerned with the dyeing methods for polyamide (nylon) textile products with a pH variation that provides the opportunity to observe, control and prevent the pH variation created by bodily fluids and contaminations in working and living environments. The said method includes the steps of fixation process, polyamide dyeing process and usage of bromophenol blue indicator. It is explained that the polyamide dyeing process is conducted between the temperatures of 40 to 120 O, the colour bath is ad ded with acids to achieve pH levels of 4 and bromophenol blue is used as the dyestuff. However, it does not mention the usage of reactive dyestuffs or mordant salts.

In the document numbered WO9845527A1 , a method regarding pre-processing of textile material with a resistance substance and the production of colour-washed fabric including the colourization of the said textile material in order to produce colour-washed fabric is described. In this regard, it is stated that the resistance substance is chosen from a group including metallic mordants and the said textile material consists of the fibres chosen from a group including cotton, linen, lteef4, wool, polyester, nylon and acrylic. Concerning the colourization process mentioned in the said document, the dye chosen from the group consisting of pigments, vat, reactive, direct, disperse, acid, sulphur, azoic, phthalocyanine, quinacridone and their combinations, is applied with a method chosen from the group consisting of atmospheric and jet dyeing, batch dyeing, jigger dyeing, pad dyeing, beam dyeing, star frame dyeing, vertical infrared dyeing and rotary drum washing/dyeing. However, specifically, it does not mention meta and post mordanting processes, the usage of reactive dyestuffs consisting of Monochlorotriazine, trifluoropyrimidine and Monochlorotriazine + vinyl sulfone functional groups and the usage of mordants as potassium aluminium sulphate dodecahydrate, iron (II) sulphate heptahydrate and tannic acid.

In the Chinese patent document numbered CN101906255A, the preparation method for natural wood dye and fabric dyeing with this natural wood dye with the mordanting process of metallic aluminium salt or metallic iron salt or without mordanting, are described. With the 7th structure mentioned in this document, the process of applying this method on nylon fabric is described. However, specifically, there is no mention of the usage of reactive dyestuff, especially reactive dyestuff including Monochlorotriazine, trifluoropyrimidine and Monochlorotriazine + vinyl sulfone functional groups and the usage of mordants as potassium aluminium sulphate dodecahydrate, iron (II) sulphate heptahydrate and tannic acid.

Upon examining the dyeing studies in the literature, it is observed that metallic salts are not used as mordants for the dyeing of nylon fabrics with reactive dyestuffs. At the same time, it is observed that only pH 4 is utilized as a dyeing solution pH and no experimental work was conducted for other pH ranges. In this regard, this condition creates the need for a method that especially improves the wet fastness values achieved as a result of dyeing, and subsequently, extends the bench life of dyed textile materials used by consumers.

In conclusion, in accordance with the above-mentioned issues and the inefficiency of the existing solutions regarding this topic, it is deemed necessary to make improvements in the relevant technical field.

Brief Description of the Invention

The current invention is concerned with a method that meets the above-mentioned requirements, eliminates all disadvantages and provides additional advantages, for the dyeing of nylon fabrics with reactive dyestuffs in the presence of metallic mordant salts.

The main purpose of the invention is, concerning the dyeing of nylon fabrics which are synthetic fibres, to develop a method for the application of reactive dyestuffs which are able to form both covalent bonds and ionic bonds with nylon fibres in the presence of metallic salt mordant chemicals.

The purpose of the invention is to develop a method that ensures the achievement of dyed textile materials with increased wet fastness values and thus, has extended bench lives. The other purpose of the invention is to provide a method with which it is possible to apply dyeing under three different pH values, namely pH 2, pH 4 and pH 6, with reactive dyestuff consisting of three different functional groups.

Another purpose of the invention is to apply one of the pre-mordanting, meta mordanting and post mordanting processes while dyeing the nylon fabrics with reactive dyestuffs.

In order for the above-mentioned goals to be actualised, invention, in the textile field, is a method to dye polyamide (nylon) textile products with reactive dyes, consisting of; i. preparation of the dyeing solution with pH levels of 2 to 6, ii. submerging the polyamide textile products into the dyeing solution, iii. adding reactive dyestuffs into the dyeing solution, iv. keeping the polyamide textile product submerged in the dyeing solution for 60 to 90 minutes, v. washing, rinsing and drying the product at the end of the dyeing process process steps and the process step of mordanting by adding mordant chemicals into the dyeing solutions before process step ii) or during process step iii) or after process step iii).

In the method subject to the invention, the pre-mordanting process is conducted by adding the mordant chemical before the process step ii).

In the method subject to the invention, the meta mordanting process is conducted by adding the mordant chemical during the process step iii).

In the method subject to the invention, the post mordanting process is conducted by adding the mordant chemical after the process step iii).

The characteristic and structural features of the invention as well as the advantages it provides can be distinctly understood with the below-given figures and the written detailed explanations referencing these figures and therefore, the evaluation must be conducted in consideration of these figures and detailed explanations. Figures to Help Understanding the Invention

Figure -1, is the process of conducting pre-mordanting.

Figure -2, is the process of conducting meta mordanting.

Figure -3, is the process of conducting post mordanting.

Drawings do not require scaling and certain details not required to understand the current invention may be discarded. Additionally, elements that are at least largely identical or have at least largely identical functions, are indicated with the same numbers.

Explanation of the References

M: Mordant

RB: Reactive Dyestuff

Detailed Explanation of the Invention

In this detailed explanation, the method subject to the invention is only explained for the topic to be better understanding of the subject.

The invention is concerned with a method of dyeing polyamide (nylon) textile products with reactive dyes in the textile field, consisting of; i. preparation of the dyeing solution with pH levels of 2 to 6, ii. submerging the polyamide textile products into the dyeing solution, iii. adding reactive dyestuffs into the dyeing solution, iv. keeping the polyamide textile product submerged in the dyeing solution for 60 to 90 minutes, v. washing, rinsing and drying the product at the end of the dyeing process process steps and the process step of mordanting by adding mordant chemicals into the dyeing solutions before process step ii) or during process step iii) or after process step iii). Said reactive dyestuffs are chosen among reactive dyestuffs that include Monochlorotriazine, trifluoropyrimidine and Monochlorotriazine +vinyl sulfone functional groups. The mordanting process in the said method can be applied as the pre-mordanting process by adding mordant chemicals before the reactive dyestuff, as meta mordanting by adding mordant chemicals together with the reactive dyestuff and as post mordanting by adding mordant chemicals after the reactive dyestuff. Said mordanting chemical is chosen among potassium aluminium sulphate dodecahydrate, iron II sulphate heptahydrate and tannic acid.

In the method subject to the invention, polyamide textile product is submerged into the dyeing solution with a temperature lower than 120 °C, preferably 102 O, and is kept there for 60 to 90 minutes.

In the method subject to the invention, with the application of the reactive dyestuffs which are able to form both covalent and ionic bonds with nylon fibres, in the presence of metallic salt mordants, wet fastness values resulting from the dyeing are improved and thus the bench lives of dyed textile materials are extended for usage. In order to achieve this, it is possible to conduct dyeing with three different functional groups of reactive dyestuffs. These functional reactive groups are Monochlorotriazine, trifluoropyrimidine and Monochlorotriazine +vinylsulfone functional groups. With these dyestuffs, three different dyeing processes can be conducted as pre-mordanting or meta mordanting and post mordanting in presence of potassium aluminium sulphate dodecahydrate, iron II sulphate heptahydrate and tannic acid metallic salts as mordants. Process graphics are shown in Figures 1 to 3.

Figure 1 shows the pre-mordanting application of the method subject to the invention. Nylon fibres are submerged into the dyeing solution at preferably 300 and then the mordant chemicals are added. Subsequently, the temperature of the solution is increased to 800 with a speed of 2 O/minute and r eactive dyestuff is added. The temperature of the solution which reactive dyestuff is added is increased to 1020 and the dyeing process is completed by keeping the nylon fabric inside the solution for 60 minutes. After this, the temperature of the solution is decreased to 500 with a speed of 4O/minute and the fabric is rinsed with water after being washed with the washing solution.

Figure 2 shows the meta mordanting application of the method subject to the invention. Nylon fibres are submerged into the dyeing solution at preferably 300 and then the mordant chemicals and reactive dyestuffs are added at the same time. Subsequently, the temperature of solution is increased to 1020 w ith a speed of 2 O/minute. Nylon fabric is kept in this solution for 60 minutes at 1020 and the dyeing process is completed. After this, the temperature of the solution is decreased to 500 with a speed of 4O/minute and the fabric is rinsed with w ater after being washed with washing solution.

Figure 3 shown the post mordanting application of the method subject to the invention. Nylon fibres are submerged into the dyeing solution at preferably 300 and then the reactive dyestuffs are added. Subsequently, the temperature of the solution is increased to 800 with a speed of 2 O/minute and m ordant chemical is added and kept for 30 minutes. The temperature of the solution added with mordant chemical is increased to 1020 and nylon fabric is kept in this solution for 60 minutes and the dyeing process is completed. After this, the temperature of the solution is decreased to 500 with a speed of 4O/minute and the fabric is r insed with water after being washed with washing solution.

In the study conducted with the method of the invention, aluminium potassium sulphate, the iron (II) sulphate and tannic acid are used as mordant chemicals for each of the dyestuff. The amounts of the said chemicals are designated by the way of weighing them at laboratory purity. At the same time, the amount of mordants used is kept between 0,1% and 1% and the dyeing studies are conducted at low rates. The amount of mordants used can be increased up to 5%. The effects of the mordant types for dyeing are examined. In the study, reactive dyestuffs consisting of monochlorotriazine, trifluoropyrimidine and monochlorotriazine +vinyl sulfone functional groups, are used. These dyestuffs are industrially applied dyestuff and no purifications have been conducted for dyeing. The dyestuffs are chosen as 0,5%, 1% and 2%. Dyeing behaviours of the functional structures of reactive groups are examined. For dyestuff solutions, pH 2, pH 4 and pH 6 values are utilized respectively. Three different processes, namely the pre-mordanting, meta mordanting and post mordanting, are developed. The dyeing process is conducted for 60 minutes at 102“C for three different dyeing processes. For three different processes, dyeing operations are conducted with different pH values and different mordant chemicals for each dyestuff percentage. The difference between pre-mordanting, meta mordanting and post mordanting methods is the step of adding different mordant chemicals to the dyestuffs at different intervals. With the pre-mordanting method, mordant chemicals are added to the solution at suitable pH values and time conditions, prior to adding the dyestuffs. With the meta mordanting method, mordant chemicals and dyestuffs are added to the solution at suitable pH values and time conditions, at the same time without any intervals. With the post mordanting method, mordant chemicals are added to the solution at suitable pH values and time conditions, after the dyestuff.

The results presented in the below-given Tables 1 to 3 belong to dyestuff fixation works of (K/S) 1 colour strength of the fabric after the dyeing, (K/S) 2 colour strength of the fabric after the extraction in 20% pyridine solution, E% percentage dyestuff absorption and T% percentage mean dyestuff absorption.

Table 1 Results of the works with 0.5% dyestuff MCT : monochlorotriazine

VS+MCT : monochlorotriazine +vinyl sulfone

TFP : trifluoropyrimidine

Table 2 Results of the works with 1% dyestuff

The amount of preferred dyestuff and mordant usable per the weight of the fabric dyed with the method subject to the invention are presented in Table 4. In this regard, it is calculated in accordance with the percentage (%) of the weight (mass) of the textile material to be dyed.

In the exemplary application of the invention, the amount (concentration) of dyestuff is designated as 5% and 5 kg of dyestuff is added to the dyeing solution in order to dye 100 kg of textile materials. When the weight of the textile material to be used is 200 kgs, the amount of dyestuff must be 10 kgs. In a different application in which the mordant amount (concentration) is chosen as 3%, for dyeing of the 100 kgs textile materials, 3 kgs of mordants are added to the dyeing solution. When the weight of the textile material to be used is 300 kgs, the amount of mordants to be used must be 9 kgs.