TR2023019045A2 - AN IMPROVED DYEING METHOD FOR DYEING CATIONIC DYEABLE POLYESTER FABRICS WITH BASIC (CATIONIC) DYEING MATERIALS - Google Patents

Abstract

The invention relates to a new dyeing method developed in the textile field for dyeing cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes. The invention relates to a continuous dyeing method that involves fixation in a thermosol oven to ensure that the dyes can diffuse into the fiber, especially when dyeing cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes.

Description

DESCRIPTION AN IMPROVED DYEING METHOD FOR DYEING CATIONIC DYABLE POLIESTER FABRICS WITH BASIC (CATIONIC) DYES Technical Field The invention relates to a new dyeing method developed for the dyeing of cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes in the textile field. The invention relates to a continuous dyeing method that includes fixation in a thermosol oven to ensure that the dyes can diffuse into the fiber, especially in the dyeing of cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes. State of the Art Polyester fibres have a very wide area of use due to their superior properties compared to other natural and man-made fibres. Polyester fiber production and use has increased every year and has become the most produced and used fiber in the world. Polyester fiber production accounts for more than half of the world fiber production. Although polyester fibers have become the primary fibers in textile production due to their superior and suitable strength properties and variety of use, they are hydrophobic fibers. The fact that the fibers have very low water absorption creates both advantages and disadvantages in terms of their use. The most important problem of polyester fibers is that they are very difficult to dye due to their hydrophobic properties. Studies on fiber internal structures and current dye classes in the market show that polyester fibers can be dyed with disperse dyes. Disperse dyes were developed primarily for dyeing cellulose acetate fibers at the end of the 1920s, and their most important feature is that they are non-ionic. It was understood that this non-ionic structure had a very high affinity in the amorphous regions of man-made fibers, and with the experiences gained from cellulose acetate fibers, it was understood that polyester fibers could be dyed with disperse dyes. However, the fact that the glass transition temperatures of polyester fibers were between 75-80"C and the dyeing temperatures were 130"C showed that it was not possible to dye polyester fibers with disperse dyes under atmospheric conditions. In this direction, the thermosol method was developed for dyeing polyester fibers with disperse dyes. This method is a continuous dyeing process and the dyeing solution containing the disperse dye is The polyester fabric is impregnated by passing it through the impregnation tank in an open width, then drying is done to remove excess water and after this drying, fixation is done in a thermosolation oven at very high temperatures for the disperse dye molecules on the fiber to diffuse into the fiber. However, this method has disadvantages such as the necessity of dyeing very large quantities of fabric batches for its efficient operation. Another method developed for dyeing polyester fibers is the Carrier dyeing process. It has been synthesized as an auxiliary chemical for Carrier dyeing and enables yarns and fabrics made of polyester fibers to be dyed with disperse dyes in machines open to the atmosphere. There are two basic theories about how the Carrier chemical behaves under dyeing conditions. According to one theory, Carrier chemicals interact with disperse dyes to provide dyeing, while according to the other theory, Carrier chemicals reduce the glass transition temperatures of polyester fibers by acting as a plasticizer in the dyeing solution and make the internal structure of the fiber openable at boiling temperatures so that disperse dyes can diffuse into the fiber. Although both theories have sub-theories, the second theory is generally accepted. According to this, Carrier chemicals allow the internal structure of polyester fibers to open at boiling temperatures. However, this method has some negative characteristics such as the fact that the Carrier chemicals produced are generally harmful to human health and nature, and the problems encountered in dyed fabrics. In addition, there are "jet dyeing machines" operating under high pressure and closed to atmospheric conditions for dyeing polyester fibers with disperse dyes. Jet dyeing machines are dyeing tanks in which dyeing can be done at temperatures up to 140"C and are resistant to approximately 4 atm pressure. It is possible to dye fabrics (or yarns) made of polyester fibers in these tanks at 130"C. Dyeings made in these machines, which operate according to the exhaust method and the principle of discontinuous dyeing, have been the basic application in coloring polyester products since the 1960s. With the successful engineering studies carried out in fiber production technology after the 1960s, it has become possible to produce new fibers that combine the properties of existing man-made (regenerated and synthetic, artificial) fibers. One of these fibers, cationic (basic) dyeable polyester fibers (CDPET; Cationic Dyeable PET), both have the superior properties of polyester fibers and, unlike disperse dyes, can be dyed with cationic (basic) dyes. In the production of CDPET fibers, anionic polymers used in the production of acrylic fibers are added to the polyester polymer, and as a result, there are two polymers in the fiber. While one of these polymers, polyester (polyethylene terephthalate, (PET)), provides the strength properties, the other added anionic polymer (copolymer) forms end groups (dyeing sites) in the fiber to which cationic (basic) dyes can make electrostatic bonds under dyeing conditions. The polymer that bonds with the dye molecules in this dyeing stage is not polyester, but anionic polymer found as a copolymer. The amount of anionic copolymer added to the polyester polymer is adjusted according to the desired properties of the CDPET fibers produced. The purpose of CDPET fiber production is to obtain fibers that can be dyed with much darker and more vivid colors as an alternative to polyester fibers. In addition, using CDPET and normal PET fibers together by blending them provides some visual features that cannot be obtained when these fibers are used alone. With this type of blend, fabrics with melange effects that consumers are very interested in are produced and are in great demand in the market. CDPET fibers are negatively charged both on the surface and internally under dyeing conditions and can form very strong ionic bonds with positively charged cationic (basic) dye molecules in the dyeing medium. This negative charge is a feature of the anionic copolymer used next to the polyester polymer and has an acidic property. In addition, the advantage of cationic (basic) dyes being the dyes that give the brightest and most vivid colors among all existing dye classes is utilized. In the technique, yarns and fabrics made of CDPET fibers, whether blended with PET fibers or not, are dyed with cationic (basic) dyes primarily in jet dyeing machines (vats) using the exhaust method and the discontinuous dyeing principle. In this discontinuous dyeing principle, the production amount is related to the capacity of the dyeing vat. In high-quantity batches, a dye intake difference called lot/batch difference occurs between the dyeings that need to be done one after the other, and as a result, color differences occur. Cationic (basic) dyeable polyester (CDPET) fibers and yarns and fabrics produced from these fibers have historically been dyed primarily using basic (cationic) dyes. Since cationic (basic) dyeable polyester (CDPET) fibers are synthetic fibers, although it is possible to dye them with disperse dyes, the targeted dark and bright dyeing results cannot be achieved. Disperse dyes are nonionic and basic dyes are cationic. Other dyes used in dyeing textile fibers are anionic and anionic dyes do not have an affinity for cationic (basic) dyeable polyester (CDPET) fibers due to their ionic structure differences. Yarns and fabrics made of cationic (basic) dyeable polyester (CDPET) fibers can be dyed with basic (cationic) dyes to very dark and bright colors. Dyeing is carried out in batches in dyeing tanks closed to the atmosphere according to the exhaust method. However, under dyeing conditions, since the internal structure and surface of cationic (basic) dyeable polyester (CDPET) fibers are negatively charged and basic dye molecules are positively charged, a very high electrostatic attraction force is formed between the fibers and the dye molecules. Due to this attraction force, the dyeing speed increases a lot and it becomes very difficult to obtain a uniform dyeing. Therefore, when dyeing cationic (basic) dyeable polyester (CDPET) products with basic (cationic) dyes according to the exhaust method, the dyeing speed must be slowed down under dyeing conditions. In this direction, temperature control, retarder chemical addition or temperature/retarder combinations are used to slow down the dyeing speed. Under dyeing conditions, the dyeing temperature is increased very slowly, dyeing is done at boiling temperature and under the acidic pH conditions that are monitored. Dyeing processes according to the exhaust method are carried out in certain weights and in batches depending on the capacity of the dyeing machine (boiler) used. However, as a result of dyeing these batches independently, errors called lot differences or batch dyeing differences occur and it is not possible to obtain the same color in each batch. Dyeing large amounts of fabric in consecutive batches in this manner according to the exhaust method causes problems in obtaining the same color. When cationic (basic) dyeable polyester (CDPET) fabrics are dyed in batch processes according to the exhaust method, they need to be in the form of fabric ropes in jet dyeing machines closed to the atmosphere and as a result, under dyeing conditions, light-colored dyed marks called fracture marks appear in the fabrics in the longitudinal direction and where the dyes cannot fully penetrate. Therefore, dyeing of cationic (basic) dyeable polyester (CDPET) products in fabric form and by exhaust method in dyeing tanks is not a widely applied process under practical industrial conditions and dyeing in yarn form is preferred. These problems encountered in dyeing by exhaust method almost always result in the use of CDPET fibers as a blend with normal PET fibers. As a result of the research conducted in the literature, the application numbered EP3992339A1 was encountered. The application in question is related to the dyed fabric and dyeing method after being turned into fabric. The method in question includes dyeing a fabric containing a meta-type fully aromatic polyamide fiber, a para-type fully aromatic polyamide fiber and a polyester fiber, a fully aromatic polyamide fiber with a dye solution containing cationic dye; dyeing a fabric containing polyester fiber with a dye solution containing disperse dye. However, the document does not specifically mention the process of dyeing cationic dyeable polyester (CDPET) fabrics directly with basic dyes. As a result, due to the above-mentioned drawbacks and the inadequacy of existing solutions on the subject, it has become necessary to make a development in the relevant technical field. Purpose of the Invention The invention is inspired by the current situation and aims to solve the above-mentioned drawbacks. The main purpose of the invention is to develop a method that allows continuous dyeing instead of discontinuous processes with the exhaust method, which causes dyeing errors in the current technique of dyeing cationic dyeable polyester (CDPET) fabrics, and where basic (cationic) dyes can be used. The purpose of the invention is to provide a method in which basic (cationic) dyes are used in the dyeing of cationic dyeable polyester (CDPET) fabrics without the need for processes such as temperature control and retarder chemical addition. Another purpose of the invention is to provide dye impregnation that allows basic (cationic) dyes to diffuse into the fiber while the fabrics remain wet during the fixation period. Another purpose of the invention is to provide fixation directly in the thermosol oven after dye impregnation applied to cationic dyeable polyester fabric without the intermediate drying step used in classical thermosol application. In order to fulfill the above-mentioned purposes, the invention is a method developed for dyeing cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes and includes the following process steps; i. Preparation of dyeing solution containing basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer and migration inhibitor, ii. Passing the cationic dyeable polyester (CDPET) fabric in an impregnation tank containing the dyeing solution, iii. Squeezing the fabric with squeezing cylinders at the impregnation tank exit, iv. Performing dye fixation by passing the fabric through a thermosol oven, v. Washing the dyed fabric and then drying it. The structural and characteristic features of the invention and all its advantages will be understood more clearly thanks to the detailed explanation given below and therefore the evaluation should be made by taking this detailed explanation into consideration. Detailed Description of the Invention In this detailed description, preferred embodiments of the method which is the subject of the invention are explained only for a better understanding of the subject. The invention relates to a method developed for dyeing cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes. The method in question includes the following process steps; i. Preparation of dyeing solution containing basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer (pH5) and migration inhibitor, ii. Passing the cationic dyeable polyester (CDPET) fabric in an impregnation tank containing the dye solution, iii. Squeezing the fabric with squeezing cylinders at the impregnation tank exit, iv. Passing the fabric through a thermosol oven to fix the dye, v. Washing and then drying the dyed fabric Table 1. Dyeing solution composition Element Name Preference by weight Usable amount (%) amount (%) Thickener 1 1-60 Carrier 8 15-30 Basic dyestuff 5 1-8 Water and weak acid 50 10-68 buffer Migration inhibitor 14 5-25 In a preferred application of the method according to the invention, in step i) a dyeing solution containing by weight 1-8% basic dyestuff, 15-30% carrier, 10-60% urea, and 5-60% migration inhibitor is prepared. Here, weak acid buffer is added to bring the pH to 5. In a preferred application of the method according to the invention, in the ii) process step, the cationic dyeable polyester (CDPET) fabric is passed through an impregnation tank containing the dyeing solution at a temperature range of 22-45"C for 1-6 seconds. In a preferred application of the method according to the invention; in the iv) process step, the fabric is passed through a thermosol oven at a temperature range of 120-220"C for 30 to 480 seconds. In a preferred application of the method according to the invention; in the v) process step, the dyed fabric is washed in cold wash, warm wash and final rinse processes, respectively. The said cold wash is carried out with water at a temperature range of 20-40"C for 20-30 minutes. The mentioned warm wash is carried out in anionic and nonionic surfactant at 50-65"C for 20-30 minutes with the solution containing the mentioned last substance. Rinsing is carried out with water at room temperature. Basic (cationic) dye: Cationic (basic) dyeable polyester (CDPET) is an organic-synthetic dye molecule that colors. It has a cationic molecular structure and is a colored cation that dissolves in the aqueous medium that performs the dyeing. The method in question can be used in dyeing woven or knitted Cationic dyeable polyester (CDPET) fabric. Thickener: It is a water retaining chemical substance that increases the consistency of the impregnation solution and ensures that the impregnation solution is retained more on the fabric after impregnation. Natural or regenerated thickeners can be used here. An example of these is carboxymethylcellulose (CMC). In addition, alginate and guar ether can be used, but are not limited to these. Carrier in the dyeing solution is an organic-synthetic chemical substance used to help open the internal structures of polyester fibers under high thermosolization temperature. Here, chlorophenoxyethanol, diphenyl, ortho- and para-hydroxydiphenyl, monochloro- ortho- hydroxydiphenyl and N-alkylphthalimide can be used as carriers (Carrier-Keriyer) but not limited to these. Urea (CH4N20) in the dyeing solution is used due to its water retention feature. Migration inhibitor in the dyeing solution: It is used to prevent displacement of the impregnation solution (flotte) on the fabric under high temperature conditions and solution migration (transfer / migration) from wet areas to dry areas. Water is the liquid that dissolves the dye and other chemicals and allows the fabric to take solution in the impregnation tank. A small amount is added to the solution for weak acid buffer pH5. Here, acetic acid or formic acid and sodium acetate can be used as weak acid buffers but not limited to these. The amount of addition is included in the total amount of water. Impregnation Tank (Fulard): This is a tank that contains impregnation solution and through which the CDPET fabric is passed and receives the impregnation solution. There are squeezing rollers on it and the impregnated fabric is passed between the squeezing rollers and a light squeeze should be made so that the float is as high as possible. Care is taken to ensure that the solution (float) is maximum. The impregnation solution is at room temperature. The pressure of the squeezing rollers is selected between 0.25 - 5.5 bar (3.5 - 80 psi). The float (%AF) received after impregnation and squeezing should be as high as possible. Thermosol Oven: This is a drying machine through which the dye-impregnated CDPET fabric is passed. It operates in an open environment to the atmosphere and according to the principle of convective (conduction) heat transfer. It has the ability to heat up to 220"C. It should be able to give homogeneous heat between 30-480 seconds in the temperature range of 120-220"C. Basic dye fixation is done inside CDPET fibers with convective heat transfer and hot drying air should be sent vertically to the front and back surfaces of the fabric from the hot air transmission channels in the machine. Thermosol oven is preferably a stenter. In a preferred example of the method in question, the following processes are followed: Step 1: Dyeing solution containing 1-8% basic dyestuff by weight, 15-30% carrier, acid buffer and 5-25% migration inhibitor is prepared. Step 2: Passing the cationic (basic) dyeable polyester fabric in an impregnation tank containing the dyeing solution between 22-45"C for 1-6 seconds, squeezing with rollers and squeeze cylinders between, fixing the dye by passing for seconds, In Step 2, the dyed fabric is washed in cold water between 20-40CC for 20-30 minutes, then in a solution containing anionic and nonionic surfactants between 50-65"C for 20-30 minutes, and then washed with a final rinse at room temperature and then dried. The drying temperature should not exceed 70C and should be terminated without over-drying. The difference of the inventive method from the existing technique is that water retention on the fabric is maintained by using thickeners, migration inhibitors and urea and the thermosoling process step is carried out directly with dry heat while the fabric is wet without intermediate drying. Carrier chemical has been used in order to open the internal structures of the fibers more easily. An experimental study with the inventive method has been carried out as follows: Parameters: Thermosoling temperatures: 180"C and 190"C Dyeing concentration: 2 grams/Liter Impregnation (dyeing) solution: 15% migration inhibitor; 5% thickener; 20% carrier; taken liquor ~ 80% Thermosoling time: 300 seconds Color nuance of basic dye: Blue Standard CDPET (Cationic Dyeable Polyethylene Terephthalate) test fabric cut in 25x25 dimensions was impregnated with the prepared dyeing solution, the taken liquor on the fabric was squeezed by passing it between the rollers to be maximum and then it was placed between the preferably stenter needles of the thermosol machine. It was fixed in a closed environment in the presence of hot air for the specified time. During this fixation, the internal structures of the fibers are opened and the basic (cationic) dye in the solution impregnated on the fabric enters the fibers and binds to the anionic groups of the copolymer in the internal structure with ionic bonds. By adding migration inhibitor, thickener and urea into the impregnation solution, water is kept in the fabric during the thermosolization period and thus the water-soluble state of basic (cationic) dyes is maintained. In the experimental study, the color coordinate values obtained from the dyeings made for two different thermosolization temperatures are given. (Table 2) The experimental study shows that the method in question works successfully.TR TR TR TR TR TR

Claims (1)

1. SYSTEMS. The invention is a method developed for dyeing cationic dyeable polyester (CDPET) fabrics with basic (cationic) dyes, and it is characterized by; i. Preparing a dyeing solution containing basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer and migration inhibitor, ii. Passing the cationic dyeable polyester (CDPET) fabric in an impregnation tank containing the dyeing solution, iii. Squeezing the fabric with squeezing cylinders at the exit of the impregnation tank, iv. Performing dye fixation by passing the fabric through a thermosol oven, v. Washing and then drying the dyed fabric. It is a method according to claim 1, and it is characterized by; i) In the process step, it is preparation of dyeing solution containing 1-8% migration inhibitor, 10-68% water and weak acid buffer by weight. It is a method according to claim 1, characterized in that; ii) in the process step, the cationic dyeable polyester (CDPET) fabric is passed through an impregnation tank containing the dyeing solution for 1-6 seconds. It is a method according to claim 1 or 3, characterized in that; ii) in the process step, the impregnation tank temperature is in the range of 22-45“C. It is a method according to claim 1, characterized in that; iv) in the process step, the fabric is passed through a thermosol oven at a temperature of 120-220“C for 30 to 480 seconds. It is a method according to claim 1, characterized in that; v) The process is to wash the dyed fabric in cold wash, warm wash and final rinse processes respectively. It is a method according to claim 6, and its feature is that the said cold wash is carried out with water at 20-40“C for 20-30 minutes. It is a method according to claim 6, and its feature is that the said warm wash is carried out in a solution containing anionic and nonionic surfactants at 50-65“C for 20-30 minutes. It is a method according to claim 6, and its feature is that the said final rinse is carried out with water at room temperature. TR TR TR TR TR TR