A dyeing method developed for dyeing acrylic fabrics with basic (cationic) dyestuffs

Abstract

The invention relates to a new dyeing method developed in the textile industry for dyeing fabrics made of acrylic fibers with basic (cationic) dyes. The invention particularly relates to a continuous dyeing method that involves fixation in a thermosol oven to enable dyes to diffuse into the fibers, for dyeing fabrics made of acrylic fibers with basic (cationic) dyes.

Description

[0001] A DYEING METHOD DEVELOPED FOR DYEING ACRYLIC FABRICS WITH BASIC (CATIONIC) DYESTUFFS

[0002] Field of the Invention

[0003] The invention relates to a new dyeing method developed in the textile industry for dyeing fabrics made of acrylic fibers with basic (cationic) dyes.

[0004] The invention particularly relates to a continuous dyeing method that involves fixation in a thermosol oven to enable dyes to diffuse into the fibers, for dyeing fabrics made of acrylic fibers with basic (cationic) dyes.

[0005] State of the Art

[0006] Today, acrylic, which is an indispensable raw material in many areas of the highly developed modern industry, is a material that is frequently used in the production of many products and different compounds. Acrylic fibers, yarns and fabrics (woven and / or knitted) produced from these fibers have historically been dyed primarily using basic (cationic) dyes. Since acrylic fibers are synthetic fibers, although it is possible to dye them with disperse dyes, the desired dark and bright dyeing results cannot be obtained in dyeing applications. Disperse dyes are nonionic dyes and basic dyes are cationic dyes. Other dyes used in the dyeing of textile fibers have anionic properties, and anionic dyestuffs have no affinity for acrylic fibers due to the ionic structure difference.

[0007] Basic (cationic) dyes are the class of dyestuff that provide the brightest and most vivid colors and their use is limited to acrylic fibers. Yarns and fabrics made of acrylic fibers can be dyed to very dark and bright colors with basic (cationic) dyes. According to the exhaust method, dyeing is carried out in batches in dyeing kiers closed to the atmosphere. However, under dyeing conditions, since the internal structure and surface of the acrylic fibers are negatively charged and the basic dye molecules are positively charged in water medium, a very high electrostatic attraction force occurs between the fibers and the dye molecules. Due to this attraction force, the dyeing rate increases very much and proper even dyeing becomes very difficult to achieve. Therefore, it is necessary to slow down the dyeing rate under dyeing conditions in the dyeing of acrylic products with basic (cationic) dyes according to the exhaust method. In this context, temperature control, retarder chemical addition or temperature / retarder combinations are used to slow down the dyeing rate. Under the dyeing conditions, the dyeing temperature is raised very slowly, dyeings are made at boiling temperature and under monitored acidic pH conditions.

[0008] The dyeing processes carried out according to the exhaust method are carried out in certain material weights and batches depending on the capacity of the dyeing machine (feer) used. However, as a result of the independent dyeing in batches, errors called lot / batch difference or batch dyeing differences occur and it is not possible to obtain the same color in each separate batch. According to the exhaust method, dyeing large amounts of fabric in successive batches in this way always causes problems in obtaining the same color.

[0009] When acrylic fabrics are dyed in batch processes according to the exhaust method, they must be in the form of fabric rope in closed atmospheric jet dyeing machines, and as a result, under dyeing conditions, traces called crack marks and light colored marks where the dyes have not fully penetrated are obtained. Due to these errors that can be encountered in batch dyeing processes of acrylic fabrics according to the exhaustion method, yarns are dyed at first in the production of colored acrylic products and then these yarns are converted into fabric by weaving and / or knitting processes. This causes additional wet processing problems after weaving or knitting. Due to these problems, the dyeing of acrylic products in fabric form and in dyeing kiers according to the exhaust method is not a commonly used process under practical industrial conditions and dyeing in yarn form is preferred. This causes problems such as wet processing problems in yarn dyeing.

[0010] As a result of the research conducted in the literature, the application numbered CN108894011 A was encountered. The said application relates to a method of preparing acrylic fibers with a high visual warning effect. In the said method, a dyeing solution comprising dyestuff, water, plasticizer, leveling agent and color fixing agent is prepared; acrylic fibers are dyed in this solution at a temperature of 80-85 'C for 40-60 minutes and then subjected to post-process. However, the document does not specifically mention the process of dyeing process with basic dyestuffs. Another application numbered US5741338A relates to a method for dyeing synthetic fibers, particularly acrylic fibers, with basic dyestuffs. In the said method, the dyeing solution is chemically modified to make the synthetic fibers receptive to basic dyestuffs. Here dyeing solution comprises cationic dyestuff and a quaternized amidoamine compound. However, the document does not mention the fixation process carried out in hot air, especially in the thermosol oven.

[0011] As a result, due to the said disadvantages and the insufficiency of the current solutions regarding the subject matter, a development is required to be made in the relevant technical field.

[0012] Objective of the Invention

[0013] The objective of the invention is to solve said disadvantages by being inspired from the current conditions.

[0014] The main objective of the invention is to develop a method that allows for the use of basic (cationic) dyes in continuous dyeing processes, rather than batch processes with the exhaust method, which causes dyeing defects in the dyeing of acrylic fibers fabrics in the current art.

[0015] The objective of the invention is to provide a method for dyeing acrylic fabrics with basic (cationic) dyes without the need for processes such as temperature control or the addition of retarder chemicals etc.

[0016] Another objective of the invention is to provide dye immersion solution content that allows the fabrics to remain wet and diffuse into the fiber of basic (cationic) dyes during the fixation period.

[0017] Another objective of the invention is to provide fixation directly in the thermosol oven without the intermediate drying step used in the classic thermosol application and after the dye impregnation applied to the acrylic fabric. In order to achieve said objectives, the invention is a method developed for dyeing fabrics made of acrylic fibers with basic (cationic) dyes, comprising the following process steps; i. Preparation of the dyeing solution comprising basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer and migration inhibitor, ii. Immersion of the acrylic fabric in an impregnation trough (padder) containing the dyeing solution, iii. Squeezing the fabric with the squeezing rollers at the exit of the impregnation trough (padder), iv. Performing the dye fixation of the fabric by having it passed through a thermosol oven, v. Washing of the dyed fabric and then drying.

[0018] The structural and characteristic features and all the advantages of the invention will be understood more clearly thanks to the detailed description given below, and therefore the evaluation should be made by taking this detailed description into consideration.

[0019] Detailed Description of the Invention

[0020] In this detailed description, the method and the preferred embodiments of the invention are described only for a better understanding of the subject.

[0021] The invention relates to a method developed for the dyeing of fabrics made of acrylic fibers with basic (cationic) dyes. The said method comprises the following process steps; i. Preparation of the dyeing solution comprising basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer (pH5) and migration inhibitor, ii. Immersion of the acrylic fabric in an impregnation trough (padder) containing the dyeing solution, iii. Squeezing the fabric with the squeezing rollers at the end of the impregnation trough (padder), iv. The fabric is passed through a thermosol oven for dye fixation, v. Washing the dyed fabric and then drying. Table 1. Dyeing solution composition

[0022] In a preferred embodiment of the method of the invention, in the process step i), a dyeing solution comprising basic dyestuff 1 -8% by weight, carrier 15-30% by weight, urea 10-60% by weight, thickener 1-60% by weight, water and weak acid buffer (pH5) 10-68% by weight and migration inhibitor 5-25% by weight is prepared.

[0023] In a preferred embodiment of the method of the invention, in the process step ii), the Acrylic fabric is passed through an impregnation trough (padder) containing fabric dyeing solution in the temperature range of 22-450 for 1-6 seconds.

[0024] In a preferred embodiment of the method of the invention, in the process step iv), the fabric is passed through the thermosol oven in the range of 120-2200 for 30 to 480 seconds.

[0025] In a preferred embodiment of the method of the invention; In the process step v), the dyed fabric is washed by cold washing, warm washing and final rinse processes respectively. Said cold washing is carried out with water for 20-30 minutes in the range of 20-400. Said warm washing is carried out for 20 -30 minutes in a solution containing anionic and nonionic surfactants in the range of 50-650. Said final rinse is carried out with water at room temperature. Basic (cationic) dyestuff: an organic-synthetic dye molecule that colors acrylic fibers. It has a cationic molecular structure and is a colored cation that dissolves in the aqueous medium.

[0026] The method of the invention can be used for dyeing woven or knitted Acrylic fabric.

[0027] Thickener: A water retaining chemical additive that increases the consistency of the the impregnation (immersion) solution and provides more retention of the impregnation solution on the fabric after impregnation. Here, natural or regenerated thickeners can be used. An example of these is carboxymethylcellulose (CMC). Additionally, alginate and guar ether can also be used.

[0028] Carrier in the dyeing solution is an organic-synthetic chemical substance used to help to open the internal structures of acrylic fibers under high thermosolling temperature. Here, as carrier, though not limited to these, chlorophenoxyethanol, diphenyl, ortho- and para-hydroxydiphenyl, monochloro-ortho-hydroxydiphenyl, and N-alkylphthalimide can be used.

[0029] Urea (CH4N2O) in the dyeing solution is used due to its water retention properties.

[0030] Migration inhibitor in the dyeing solution is used to prevent the displacement of the dye solution (dyeing liquor) on the fabric under high temperature conditions and the migration (transfer) of the solution from wet areas to dry areas.

[0031] Water is the liquid that dissolves water-soluble dyestuff and other chemicals, allowing the fabric to absorb the solution in the impregnation trough (padder) .

[0032] A small amount of weak acid buffer pH5 is added to the solution. Here, as a weak acid buffer, though not limited to these, acetic acid or formic acid and sodium acetate can be used. The amount of additive is within the total amount of water.

[0033] Impregnation Trough (Padder: It is the vessel (vat) in which there is a dye (immersion / impregnation) solution and in which the acrylic fabric is passed through it to absorb the the dye solution. There are squeezing rollers (cylinders) on it and the impregnated fabric is passed through the squeezing rollers and the "Amount of Liquor Pick-Up (% Pick-Up)" (amount of dye solution taken into the fabric) is adjusted. The dye solution uptake should be maximized by applying gentle squeezing as much as possible. Care is taken to ensure maximum uptake of the solution (dyeing liquor). The dye liquor is at room temperature. The pressure of the squeezing rollers is selected between 0.25 to 5.5 bar (3.5 to 80 psi). The pick-up ratio (%PU) of the dye liquor obtained after immersion and squeezing should be as high as possible.

[0034] Thermosol Oven (stenter): It is the drying machine through which the dye impregnated acrylic fabric passes. It operates in an open-air environment and based on convective heat transfer principles. It has the capability to heat up to 2200. It should be able to provide homogeneous heating in the range of 120-2200 for 30-480 seconds. Basic dye fixation is performed into acrylic fibers through convective heat transfer, and the hot drying air should be directed perpendicularly to the front and back surfaces of the fabric through the hot air transmission channels inside the machine.

[0035] In a preferred embodiment of the method of the invention, the following processes should be followed:

[0036] 1 . Step: A dyeing solution comprising basic dyestuff 1-8% by weight, carrier 15-30% by weight, urea 10-60% by weight, thickener 1-60% by weight, water and weak acid buffer 10-68% by weight and migration inhibitor 5-25% by weight is prepared.

[0037] 2. Step: Passing the acrylic fabric in an impregnation trough (padder) containing the dyeing solution in a range of 22-450 for 1-6 secon ds,

[0038] 3. Step: The fabric is squeezed with the squeezing rollers at the exit of the impregnation trough (padder), with pressures ranging from 0.25 to 5.5 bar (3.5 to 80 psi).

[0039] 4. Step: The fabric being passed through a thermosol oven (stenter) at temperatures ranging from 120-2200 for a duration of 30 to 480 seconds to perform the fixation of the dye,

[0040] 5. Step Washing of the dyed fabric by cold washing at 20-400 for 20-30 minutes, followed by warm washing in a solution containing anionic and nonionic surfactants at 50-650 for 20-30 minutes, and doing the final rins e processes at room temperature and drying it afterwards. The drying temperature should not exceed 70cC, and the drying process should be concluded without excessive drying.

[0041] The difference of the method of the invention from the present art is that the water retention on the fabric is maintained with the use of thickener, migration inhibitor and urea, and the thermosoling process step is performed directly with dry heat while the fabric is still wet without intermediate drying. In order to open the internal structures of the fibers more easily, a carrier chemical was used.

[0042] An experimental study with the method of the invention was carried out as follows:

[0043] Parameters:

[0044] Thermosolling temperatures: 1800 and 1900

[0045] Dyeing concentration: 2 gram / Liters

[0046] Dyeing solution: 15% migration inhibitor ; 5% thickener ; 20% carrier ; 20% urea, water filling it to 2 liters, dyeing liquor %pick-up ~ %80, acid buffer pH5

[0047] Thermosoling time: 300 seconds

[0048] The color nuance of the basic dye: Blue

[0049] The dyeing solution was impregnated into the standard cutout of the acrylic test fabric sized 25x25, the fabric was passed through the squeezing rollers while the taken the dyeing liquor being maximum and was preferably placed between the stenter pins of the thermosol machine. The fixation was carried out in a closed environment in hot air presence for the specified duration. During this fixation, the internal structures of the fibers are opened and the basic (cationic) dye in the solution impregnated on the fabric enters (diffuses) into the fibers and binds to the anionic groups of the copolymer in the internal structure with an ionic bond.

[0050] In the experimental study, the color coordinate values obtained from the dyeing performed for two different thermosoling temperatures are given. (Table 2) The experimental study demonstrates that the method according to the invention operates successfully.

[0051] Table 2: Experimental study data

Claims

CLAIMS1. A method developed for the dyeing of fabrics made of acrylic fibers with basic (cationic) dyes, characterized by comprising; the following process steps: i. Preparation of the dyeing solution comprising basic (cationic) dyestuff, carrier, urea, thickener, water, weak acid buffer and migration inhibitor, ii. Immersion of the acrylic fabric in an impregnation trough (padder) containing the dyeing solution, iii. Squeezing the fabric with squeezing rollers at the exit of the impregnation trough (padder), iv. Performing the dye fixation of the fabric by having it passed through a thermosol oven, v. Washing the dyed fabric and then drying.

2. The method according to claim 1 , characterized in that; in the process step i) a dyeing solution comprising 1 -8% basic dyestuff by weight, 15-30% carrier by weight, 10-60% urea by weight, 1 -60% thickener by weight, 5-25% migration inhibitor by weight, 10-68% water and weak acid buffer (Ph 5) by weight is prepared.

3. The method according to claim 1 , characterized in that; in the process step ii), the acrylic fabric is passed through a impregnation trough (padder) containing the dyeing solution for 1-6 seconds.

4. The method according to claim 1 or 3, characterized in that; in the process step ii), the temperature of the dyeing solution in the impregnation trough (padder) being in the range of 22-450.

5. The method according to claim 1 , characterized in that; in the process step iv), the fabric is passed through the thermosol oven in the range of 120-2200 for 30 to 480 seconds.

6. The method according to claim 1 , characterized in that; in the process step v), the dyed fabric being washed with cold washing, warm washing, and final rinse processes respectively.

7. The method according to claim 6, characterized in that; the said cold washing is carried out with water for 20-30 minutes in the range of 20-40'C.

8. The method according to claim 6, characterized in that; the said warm washing is carried out in a solution containing anionic and nonionic surfactants for 20-30 minutes in the range of 50-65'C.

9. The method according to claim 6, characterized in that; the said final rinse is carried out with water at room temperature.

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