Method for packaging and dyeing fabric by using indigo vegetable dye

Abstract

The invention provides a method for packaging and dyeing a fabric by using an indigo plant dye, which comprises the following steps: mixing an indigo dye, caustic soda, a reducing agent and water to prepare a dye solution; the concentration of the indigo dye is 0.3-0.6 g / L, the concentration of the caustic soda is 1-2 g / L, and the concentration of the reducing agent is 1.5-3 g / L; the dye liquor is used for carrying out normal-temperature dip dyeing on rolled and unfolded natural fiber to-be-dyed cloth, the cloth passes through a ventilation frame and a cloth guide roller connected with the ventilation frame to be subjected to air oxidation, the air oxidation time is 30-60 minutes, then washing and drying are carried out, and the dyed fabric is obtained. The retention time of the gray fabric in ventilated air is prolonged mainly by additionally arranging the ventilation frame and the like, so that the oxidation time in the dyeing process is effectively prolonged, the problems of light color, poor color and the like of vegetable dye indigo dyeing are solved, and the product quality and the working efficiency are improved.

Description

Technical Field

[0001] The invention relates to a package dyeing method for fabrics using indigo plant dyes, and belongs to the technical field of textile printing and dyeing. Background Art

[0002] At present, many synthetic dyes produce harmful byproducts or intermediates during processing. Among them, some azo dyes that may release carcinogens have been banned by many countries; the harmful waste liquid discharged during the dyeing and finishing process is also worrying. Therefore, it is very necessary to find and develop environmentally friendly dyes and dyeing methods.

[0003] As people pay more and more attention to environmental protection and health, natural dyes are regaining favor. Natural dyes are generally derived from plants, animals and minerals, and plant dyes are currently the main ones. Plant dyes are extracted from the roots, stems, leaves and fruits of plants, such as indigo, madder, lithospermum, safflower, mulberry, tea, etc. my country has rich plant dye resources and a long history of plant dyeing. As long as they are reasonably developed, they can not only obtain considerable social and economic benefits, but also help maintain ecological balance and improve the ecological environment. Using natural plant dyes to dye natural fiber fabrics can not only increase the added value of the products, but also realize the naturalness of clothing fabrics, which meets the requirements of people in the new century for clothing products, and can be used to develop colored textiles for "ecological clothing" and "all-green clothing".

[0004] The raw materials for processing natural indigo dye are mainly the leaves of the Acanthaceae plant Indigofera tinctoria. Indigo can be used to dye natural fibers. Natural indigo dye is usually a dark blue powder with a metallic luster; it sublimates at about 300°C and decomposes at 390°C; it is insoluble in water, alcohol or ether, but soluble in hot chloroform; it can be made into derivatives by sulfonation or bromination reactions; it can be reduced to leuco indigo white by insurance powder or glucose and sodium hydroxide. Therefore, fabric indigo dyeing is generally reduction dyeing, that is, oxidation is carried out first, and caustic soda insurance powder or glucose is used to reduce and color after the dye liquor reaches the cloth surface. The oxidation methods are mainly hydrogen peroxide oxidation and air oxidation. If the oxidation is not good, it will cause defects such as light color, color flower, no coloring, and color difference. The existing package dyeing and long-machine dyeing are both continuous dyeing, which easily leads to insufficient ventilation time in the indigo dyeing process, insufficient oxidation process, and poor dyeing effect. Summary of the invention

[0005] In view of this, the present invention provides a package dyeing method for fabrics using indigo plant dyes. Through the efficient indigo dyeing method of the present invention, the obtained dyed fabric product has a good color depth and uniform effect.

[0006] The present invention provides a package dyeing method for fabric using indigo plant dye, comprising the following steps:

[0007] Mixing indigo dye, caustic soda, a reducing agent and water to prepare a dye solution; the indigo dye concentration is 0.3-0.6 g / L, the caustic soda concentration is 1-2 g / L, and the reducing agent concentration is 1.5-3 g / L;

[0008] The natural fiber cloth to be dyed is impregnated with the dye solution at room temperature, and the cloth is passed through a ventilation rack and a cloth guide roller connected thereto for air oxidation for 30 to 60 minutes, and then washed and dried to obtain a dyed fabric.

[0009] In a specific embodiment of the present invention, the room temperature immersion dyeing is two-pass room temperature immersion dyeing in the first roll-to-roll dyeing equipment; during the air oxidation process, the cloth guide roller connected to the ventilation rack is arranged in the second roll-to-roll dyeing equipment and rotates two or three times.

[0010] In a specific embodiment of the present invention, the temperatures of the room temperature dyeing and air oxidation are 20-30° C. respectively.

[0011] In a specific embodiment of the present invention, the reducing agent is hydrosulfur powder, and the reducing agent concentration is 1.5-2.5 g / L; and the mixing is performed under stirring conditions.

[0012] In a specific embodiment of the present invention, the natural fiber cloth to be dyed is pre-treated cotton woven grey cloth.

[0013] In a specific embodiment of the present invention, a softener finishing step is further included between the washing and drying.

[0014] In a specific embodiment of the present invention, the water washing is hot water washing at 80-95° C., and the water washing time is 8-15 minutes.

[0015] In a specific embodiment of the present invention, the drying is drying at 80-100° C., and the drying time is 3-5 minutes.

[0016] The present invention first prepares dye liquor according to a certain weight ratio, wherein the indigo dye is 0.3-0.6 g / L, the caustic soda is 1-2 g / L, and the reducing agent is 1.5-3 g / L; then, the dye liquor is used to impregnate the natural fiber cloth to be dyed at room temperature, and the cloth is passed through the ventilation rack and the cloth guide roller connected thereto for air oxidation, and the air oxidation time is 30-60 minutes, and then washed and dried to obtain the dyed fabric. The process of the present invention is modified on the basis of existing equipment, and the technical difficulties of dyeing the special dye of plant dye indigo dyeing are solved, and a plant dye indigo dyeing package dyeing process is successfully developed; the present invention mainly increases the residence time of the grey cloth in the ventilation air by adding a ventilation rack, etc., thereby effectively increasing the oxidation time in the dyeing process, solving the problems of light color and color flower of plant dye indigo dyeing, and improving product quality and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a schematic diagram of the equipment flow of the indigo dyeing process in some embodiments of the present application;

[0019] Figure 2 This is a comparison diagram of dyeing samples of Example 1 of the present invention. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the technical scheme of the present invention is now described in detail below in conjunction with specific embodiments. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0022] However, the existing continuous indigo dyeing of fabrics has problems such as poor ventilation, light dyeing, and poor color effects.

[0023] In view of the shortcomings of the prior art, the present invention provides a package dyeing method for fabric using indigo plant dye, comprising the following steps:

[0024] Mixing indigo dye, caustic soda, a reducing agent and water to prepare a dye solution; the indigo dye concentration is 0.3-0.6 g / L, the caustic soda concentration is 1-2 g / L, and the reducing agent concentration is 1.5-3 g / L;

[0025] The natural fiber cloth to be dyed is impregnated with the dye solution at room temperature, and the cloth is passed through a ventilation rack and a cloth guide roller connected thereto for air oxidation for 30 to 60 minutes, and then washed and dried to obtain a dyed fabric.

[0026] In the embodiment of the present invention, the dye solution is first prepared, preferably including: accurately weighing the following components by weight percentage, 0.3-0.6 g / L of indigo dye, 1.0-2.0 g / L of caustic soda, and 1.5-2.5 g / L of sodium hypochlorite; accurately weighing the caustic soda, dissolving it with cold water, preferably slowly adding the indigo dye thereto under stirring conditions, adding the remaining water after stirring evenly, adding the sodium hypochlorite after stirring evenly, and continuing to stir evenly until there are no dye lumps; water should be added in small amounts in multiple times during the material mixing process.

[0027] The indigo dye involved in the embodiment of the present invention is a natural indigo-type reduction dye, using commercially available products (the plant dyes described in the present invention are all purchased from China Textile Science Research Institute Co., Ltd.); its concentration in the dye liquor can be 0.3g / L, 0.4g / L, 0.5g / L, 0.6g / L, etc. Caustic soda is also called caustic soda, caustic soda, and caustic soda. It can usually be divided into flake caustic soda, granular caustic soda, and solid caustic soda according to its form. The main chemical component is sodium hydroxide, which has strong alkalinity; the embodiment of the present application uses commercially available industrial-grade flake caustic soda, and its concentration in the dye liquor is preferably 1.1-1.8g / L, and further 1.3-1.6g / L. In the embodiment of the present invention, insurance powder is used as a reducing agent, and insurance powder is sodium dithionite (Na2O4S2), and the concentration is preferably 1.7-2.2g / L, and further 1.8-2.0g / L.

[0028] Moreover, the natural fiber cloth to be dyed involved in the embodiments of the present invention is generally a pre-treated cotton woven grey cloth, and there are no special restrictions on its fabric structure, specifications, etc., such as plain weave, twill and combined fabric structures. The yarn specification is mainly 40S, which can be pure cotton, or a blend of cotton and other cellulose fibers; the warp density can be 110-122 strands / cm, and the weft density is 84-96 strands / cm, such as double-layer fabrics such as double-layer crepe, and the conventional width can be used. The exemplary specifications of the cloth to be dyed include: C40*40 (S twist)_110*84_83"QM double-layer crepe, C40s*JC40s (z strong twist)_122*96_92.5"_double layer, double-layer crepe C40*40 (S twist)_110*84_99", C40*40 (S twist)_110*84_99" double-layer crepe, etc.

[0029] For details on equipment modification suitable for the indigo dyeing process of the embodiment of the present invention, see Figure 1, where 0 is a cloth cart, 1 is a package dyeing machine No. 1, 2 is a ventilation rack, and 3 is a package dyeing machine No. 2. Cloth cart 0 is mainly used to import the unrolled cloth, and there is no special restriction. The package dyeing machine involved in this application is referred to as a package dyeing machine, also known as a dyeing vat, which is a flat fabric dyeing equipment, mainly composed of a dyeing trough, a cloth roller, and a cloth guide roller. The dyeing process of the package dyeing machine includes: the fabric is first wound on the first cloth roller in a flat width, and then wound on another cloth roller after passing through the dye liquid. When the fabric is about to be wound, it is rewound onto the original cloth roller. Each winding is called a pass, and this is repeated until the dyeing is completed; the bath ratio is generally 3:1 to 5:1. Some roller dyeing machines are equipped with automatic control facilities such as fabric tension, turning and running speed, which can reduce fabric tension and reduce the labor intensity of workers.

[0030] The dyeing method of the embodiment of the present invention adds a package dyeing machine to the original package dyeing process, that is, it includes package dyeing machine No. 1 1 and package dyeing machine No. 2 3; and a ventilation rack 2 is added between the two package dyeing machines, which is used to draw the pre-treated grey cloth to be dyed (introduced from the cloth car 0) from the package dyeing machine No. 1 1 after being immersed in the dye solution, and then pulled to the cloth guide roller of the package dyeing machine No. 2 2 through the crossbeam on the ventilation rack.

[0031] Specifically, the No. 1 package dyeing machine 1 is the first package dyeing equipment, in which two passes of normal temperature immersion and rolling dyeing are performed, and the indigo is reduced to leuco indigo white by the insurance powder; the normal temperature is generally 20-30°C. In addition, the dyeing speed of the No. 1 package dyeing machine 1 can be 50±5 turns / min, and the tension is 8kg; the No. 2 dyeing machine can also hold dye liquor, and the number of back and forth immersions is determined according to the required color depth. The two immersions refer to the two immersions of the dye liquor of the two dyeing machines. The dyeing speed of the No. 2 dyeing machine can be 50±5 turns / min, and the tension is 8kg; the bath ratio of the two immersions is 1:15-1:20 (the depth of dyeing depends on the number of back and forth trips between the two dyeing machines. The dyeing depth will deepen with one round trip. Compared with traditional immersion dyeing, the bath ratio has less effect on the color depth).

[0032] The cloth soaked in the dye solution is led out to the ventilation rack 2, which includes a bracket, a crossbeam and a guide roller (the structure is well known to those skilled in the art), so that the cloth is placed in the air for oxidation for a certain period of time and is pulled into the No. 2 package dyeing machine 3; the No. 2 package dyeing machine 3 is the second package dyeing equipment, in which the guide roller rotates two or three times for further air oxidation. Preferably, the temperature of the air oxidation is 20-30°C, and the total time is 30-60 minutes, specifically 30 minutes.

[0033] After air oxidation, the embodiment of the present invention washes the fabric with hot water, and can be post-finished with a softener, and finally the fabric is dried to obtain an indigo-dyed fabric product. Among them, the water washing in the reduction dyeing process of the embodiment of the present invention is a hot water washing at 80 to 95°C, and the washing time can be 8 to 15 minutes. In the post-finishing process, the softener mainly includes silicone softeners, polyethylene wax softeners, and soft film softeners. Preferably, polyethylene wax softeners 10±5g / L are used. The ratio of the three types of softeners is adjusted according to the customer's hand feel requirements and seam slip index. The more silicone softeners, the worse the seam slip index; the more polyethylene wax and soft film softeners, the harder the hand feel and the better the seam slip index. The drying is preferably drying at 80 to 100°C, and the drying time can be 3 to 5 minutes.

[0034] According to tests, the dyed fabric product obtained by the efficient indigo dyeing method of the present invention has a good color depth and uniform effect.

[0035] In order to better illustrate the present invention, the following examples are further illustrated. In the examples, all raw reagents and materials are commercially available, and the experimental methods without specific experimental conditions are conventional methods and conditions well known in the art.

[0036] Among them, the plant dyes described in the present invention are all purchased from China Textile Science Research Institute Co., Ltd., and other reagents are all purchased from McLean's official website. The specifications of the cloth to be dyed are not limited. The instrument used to test the color fastness of the fabric is developed by Shandong Textile Science Research Institute, model LFY-302; the sun exposure climate test machine is developed by Wenzhou Textile Instrument Factory, model YG (B) 611-6, generally pure cotton and Tencel used at that time. The specifications are C40*40_110*84_83" double crepe, C40*40 (S twist)_110*84_99" double crepe, C40s*JC40s (z strong twist)_122*96_92.5"_double layer, C40*40_139*68_2 / 1.

[0037] Comparative example (original process):

[0038] Prepare dye solution: accurately weigh the following components by weight percentage: 0.6 g / L indigo dye, 1.5 g / L caustic soda, 1.8 g / L insurance powder; accurately weigh the caustic soda and dissolve it in cold water, slowly add the indigo dye into it under stirring conditions, add the remaining water and insurance powder after stirring evenly, continue to stir evenly until there are no dye lumps, filter and use after dissolving evenly; add water in small amounts several times during the material mixing process.

[0039] Add the prepared dye solution into No. 1 dyeing machine, pass the cloth to be dyed into No. 1 roll dyeing machine for two dyeing at room temperature (25±5℃), then wash with hot water (90℃) for 9 minutes, add softener according to the hand feel requirements for post-finishing, and dry the cloth. The type and amount of softener are determined according to the customer's hand feel requirements. Generally, polyethylene wax softener 10±5g / L is used.

[0040] Compared with the customer's sample, the color is 2-3 levels lighter, and other indicators are as shown in Table 1; the color is serious, see Figure 2 The upper cloth.

[0041] Example 1

[0042] Prepare dye solution: accurately weigh the following components by weight percentage: 0.6g / L indigo dye, 1.5g / L caustic soda, 1.8g / L hydrosulfite; accurately weigh caustic soda and dissolve it in cold water, slowly add indigo dye to it under stirring conditions, add the remaining water after stirring evenly, add hydrosulfite after stirring evenly, and continue stirring evenly until there are no lumps of dye. Check whether the dye is uniform by dripping the dye solution infiltration circle; if the infiltration circle spreads evenly around, it means that the dissolution is uniform and a true solution of homogeneous dye solution is made.

[0043] The prepared dye solution is added to dyeing machine No. 1 and dyeing machine No. 2 (both bath ratios are 1:20, package dyeing speed is 50+-5 turns / min, and tension is 8kg), the cloth to be dyed (C40*40_139*68_2 / 1) is passed through the No. 1 package dyeing machine, dyed with the dye solution at room temperature of 25°C for two passes, passed through the cloth guide roller on the ventilation rack, and then connected to the cloth guide roller in the No. 2 package dyeing machine for two passes, dyed with the dye solution at room temperature of 25°C, and oxidized in air for 30 minutes; then washed with hot water at 90°C for 9 minutes, softener was added for post-finishing (the same as the original process), and the cloth was dried at a temperature of 100°C for 3 minutes to obtain a dyed fabric.

[0044] The technician takes samples and compares them with the customer's samples to evaluate the color difference of 4 levels. Other indicators are shown in Table 1; see Figure 2 The lower layer of cloth is dyed evenly (the workshop is short of cloth carts, and cloth dyed by two processes is placed in one cloth cart).

[0045] Example 2

[0046] Prepare dye solution: accurately weigh the following components by weight percentage: 0.3g / L indigo dye, 1.5g / L caustic soda, 1.8g / L sodium hypochlorite; accurately weigh caustic soda and dissolve it in cold water, slowly add indigo dye into it under stirring conditions, add the remaining water after stirring evenly, add sodium hypochlorite after stirring evenly, and continue stirring evenly until there are no lumps of dye. Check whether the dye is uniform by dripping the dye solution infiltration circle; if the infiltration circle spreads evenly around, it means that the solution is uniform and a true solution of homogeneous dye solution is made.

[0047] The prepared dye solution is added to dyeing machine No. 1, and the cloth to be dyed is passed into dyeing machine No. 1 and dyeing machine No. 2 (the process is the same as that in Example 1), and the cloth is dyed with the dye solution at room temperature of 23° C. for two passes, and the cloth is passed through the cloth guide roller on the ventilation rack, and then connected to the cloth guide roller in dyeing machine No. 2 for two passes, and air oxidized for 30 minutes; then washed with hot water at 90° C. for 15 minutes, softener is added for post-finishing, and the cloth is dried at a temperature of 98° C. for 5 minutes to obtain a dyed fabric.

[0048] The technician takes samples and evaluates the color difference by 3-4 levels compared with the customer's samples. Other indicators are shown in Table 1.

[0049] Table 1 Comparison of test results of new and old processes

[0050]

[0051] Example 3

[0052] Prepare dye solution: accurately weigh the following components by weight percentage: 0.6g / L indigo dye, 1.5g / L caustic soda, 1.8g / L hydrosulfite; accurately weigh caustic soda and dissolve it in cold water, slowly add indigo dye to it under stirring conditions, add the remaining water after stirring evenly, add hydrosulfite after stirring evenly, and continue stirring evenly until there are no lumps of dye. Check whether the dye is uniform by dripping the dye solution infiltration circle; if the infiltration circle spreads evenly around, it means that the dissolution is uniform and a true solution of homogeneous dye solution is made.

[0053] Add the prepared dye solution into dyeing machine No. 1, pass the cloth to be dyed (C40*40_139*68_2 / 1) into dyeing machine No. 1, dye it twice with dye solution at room temperature 25°C, pass the cloth through the cloth guide roller on the ventilation rack, and then connect it to the cloth guide roller in dyeing machine No. 2 for two passes, and oxidize it with air for 30 minutes; then wash it with hot water at 98°C for 10 minutes, add softener for post-processing, and dry it at 98°C for 5 minutes to obtain dyed fabric.

[0054] The technician takes samples and compares them with the customer's samples to assess the color difference in 4 levels.

[0055] The dosage of the main dyes used in Example 2 and Example 3 is different. The test result of the dark color in Example 1 shows that the sunlight level is high and the rubbing fastness is slightly low.

[0056] The best production method for dyeing plant sulfur dyes is usually long-machine dyeing, using eight rolling tanks, that is, the 8-dip 8-roll method. However, this application boldly attempts to dye in a roll-to-roll dyeing machine to complete the task of dyeing plants in small batches and multiple varieties. The new roll-to-roll dyeing process is compared with the existing dyeing method of 8-dip 8-roll, as shown in the following table.

[0057] Table 2 Comparison between the long lathe process and the process of this application

[0058]

[0059] It can be seen from the above embodiments that, based on the existing equipment, the improved process of the present invention solves the technical difficulties of dyeing a special dye, indigo dyeing with plant dyes, and successfully develops a plant dye indigo dyeing package dyeing process. The present invention mainly increases the residence time of the grey cloth in the ventilated air by adding ventilation racks, etc., thereby effectively increasing the oxidation time during the dyeing process, solving the problems of light color and color spots of indigo dyeing with plant dyes, and improving product quality and work efficiency.

[0060] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A package dyeing method for fabrics using indigo plant dyes, characterized in that: The following steps are involved: Mixing indigo dye, caustic soda, a reducing agent and water to prepare a dye solution; the indigo dye concentration is 0.3-0.6 g / L, the caustic soda concentration is 1-2 g / L, and the reducing agent concentration is 1.5-3 g / L; The natural fiber cloth to be dyed is impregnated with the dye solution at room temperature, and the cloth is passed through a ventilation rack and a cloth guide roller connected thereto for air oxidation for 30 to 60 minutes, and then washed and dried to obtain a dyed fabric.

2. The package dyeing method according to claim 1, characterized in that The room temperature immersion dyeing is two-pass room temperature immersion pad dyeing in the first package dyeing equipment; during the air oxidation process, the cloth guide roller connected to the ventilation frame is arranged in the second package dyeing equipment and rotates two or three times.

3. The package dyeing method according to claim 2, characterized in that The temperatures of the room temperature dyeing and air oxidation are 20-30°C respectively.

4. The package dyeing method according to any one of claims 1 to 3, characterized in that The reducing agent is hydrosulfur powder, and the reducing agent concentration is 1.5-2.5 g / L; the mixing is performed under stirring conditions.

5. The package dyeing method according to any one of claims 1 to 3, characterized in that: The natural fiber cloth to be dyed is pre-treated cotton woven grey cloth.

6. The package dyeing method according to any one of claims 1 to 3, characterized in that: The step of post-treatment with a softener is also included between the washing and drying.

7. The package dyeing method according to claim 6, characterized in that The water washing is performed by washing with hot water at 80 to 95° C., and the washing time is 8 to 15 minutes.

8. The package dyeing method according to claim 7, characterized in that The drying is performed at 80-100° C., and the drying time is 3-5 minutes.

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