KR20210120231A - A Dyeing Method of Natural Indigo Color to a Silk - Google Patents

Abstract

The present invention relates to a method for dyeing silk with a natural indigo color, and more specifically, to a method for dyeing silk yarn with a natural indigo color using a cheese dyeing machine. According to the present invention, independent specialized technology is secured through establishment of silk natural indigo yarn dyeing technology using a cheese dyeing machine, and natural dyeing-weaving-processing processes are connected to each other via a one-stop line, and thus, commercialization/mass production can be realized immediately, and independent production of natural indigo dyed silk denim/denim-like material is possible. Through combination of domestic silk weaving technology and natural dyeing technology, development of specialized materials and industrialization of natural dyeing can be realized. Fabric quality enhancement implemented is realized by applying natural dyeing technology, and commercialization for creation of high-added value can make a breakthrough with a new item in the highly competitive textile market and enable preemption in the overseas high-quality materials market.

Description

{A Dyeing Method of Natural Indigo Color to a Silk}

The present invention relates to a method for dyeing natural indigo color on silk, and more particularly, to a method for dyeing natural indigo color on silk yarn using a Cheese Dyeing Machine.

Denim is a representative global long-seller product in which natural fading is expressed in design on the premise of the washing effect of ombre warp and white weft yarn dyed with indigo. Indigo dye is the most used dye among all dyes as a single dye.

Conventional indigo dyeing was mainly done by rope dyeing, but in this method, it is quickly buried only on the surface of the cotton yarn so that the liquid is not evenly injected to the core of the yarn and passes through it, repeating the process of oxidizing color in the air, and turning it into blue color. As a method of dyeing, there is a specific problem of color transfer (or water loss), which causes consumer complaints, etc. The demand for improving the fastness of denim products is very high.

On the other hand, the indigo dye representing the blue color of denim is a representative vat dye. The name of vat dye is derived from the fact that the reduction operation is called vat when dyeing and the reduction bath is called vat. It is characterized in that it has good dyeing properties for fibers and is superior to other dyes in terms of fastness.

Vat dyes are classified into anthraquinone-based dyes and indigo-based dyes based on their chemical structure. Indigo has been used for a long time as a main component of natural dye, but now synthetic indigo is mainly used. The chemical structure of indigo dye is as follows.

[Structural formula 1] Chemical structure of indigo

When the insoluble indigo vat dye is reduced by acid treatment and treated again with a strong alkali (pH 12-15) in the presence of NaOH, it becomes a soluble leuco salt and is dissolved in the salt bath. Indigo bat dyeing is made by oxidizing the leuco salt to the fiber and then oxidizing it again to develop an indigo blue color.

Indigo dye having such a dyeing mechanism requires a lot of attention because it is not easy to dye because it is an oxidation-reduction dyeing method. The reduction rate and color may vary depending on the reduction temperature, the amount of reducing agent, and the amount of dye. If over-reduced or non-reduced, the dyeing is unstable, such as color change, deterioration of dyeability, fastness, and color difference from lot to lot. , in particular, it is very sensitive to pH, so the pH must be thoroughly controlled to increase dye efficiency and reproducibility.

Since the dye itself has low fiber affinity, the amount of fixing to the fiber in the dye bath does not increase significantly over time, and it is completely fixed to the fiber only after being oxidized to insoluble indigo. Fastness is improved, and K/S can be increased by adding a neutral salt. In addition, since the absorption rate of the dye is fast, it is easy to become a non-uniform salt, so a penetrant or a leveling agent can be added. In particular, since a large amount of strong alkali and reducing agent are used in the reduction process, when dyeing silk, it is necessary to establish dyeing conditions that can maximize dyeability while reducing fiber damage caused by alkali and reducing agents.

On the other hand, indigo dye is generally a dye that is friendly to cellulose fiber dyeing, and the method of dyeing under alkaline conditions is common. However, alkaline areas are fatal for animal fibers such as silk and wool, and are not suitable for dyeing them. In addition, problems such as unevenness, dyeing and color fastness may occur due to insoluble content and dye residues contained in natural indigo dye. Domestic indigo natural dyeing is mainly fabric dyeing, and the dyeing of yarn is not done. There is a limit to commercial use in a small amount, and problems such as unevenness, color difference, fastness, etc. may occur due to insoluble matter and dye residue contained in natural indigo dye.

Accordingly, it is necessary to develop a yarn dyeing method capable of increasing the amount of dyeing of silk fibers.

The present invention aims to develop a yarn dyeing technology of indigo bat dye of silk fibers and provide a dyeing method that can improve the low fastness of existing indigo dyes, and furthermore, to develop high value-added silk denim or denim-like fabrics do.

In addition, an effective yarn-dying method of natural indigo silk yarn using a high-pressure cheese dyeing machine, a natural indigo dyeing method with excellent dyeability and fastness (compared to existing denim fabrics) even with a small amount of silk fiber dye, and a large quantity of dyeing reproducibility We want to provide dyeing technology that can be produced.

In order to achieve the above object of the present invention, the present invention provides:

A winding process of winding silk yarn on a cheese bobbin using a cheese dyeing machine,

Pre-treatment process to remove impurities of silk yarn and sericin unique to silk yarn,

A re-winding process of rewinding the pre-treated silk yarn to a cheese bobbin at an appropriate density;

A process of accommodating the re-wound silk yarn in a cheese dyeing machine and preparing a reducing bath by adding water and a reducing agent;

After heating the reducing bath, a process of dyeing the dye solution on silk yarn by adding a reduced salt solution prepared by mixing a natural indigo dye, a reducing agent, and an alkali agent;

A process of uniformly oxidizing the dyed silk yarn to the inside by adding hydrogen peroxide to develop color;

A process of soaking the colored silk yarn and then washing it with hot water to remove residual impurities and unfixed dye;

post-treatment process, and

It provides a method for natural indigo dyeing of silk, characterized in that it includes a centrifugal dehydration and hot air drying process.

In one embodiment of the present invention, the reducing salt solution is characterized in that the alkaline pH of 11 to 12.5.

In another embodiment of the present invention, the reducing bath is characterized in that the neutral or weakly acidic range of pH 5-7, preferably pH 6.6.

In another embodiment of the present invention, the reducing agent added to the reducing bath is hydrosulfite (Na ₂ S ₂ O ₄ ) It is characterized in that.

In another embodiment of the present invention, the process of dyeing the salt solution is characterized in that it is carried out in a neutral or weak alkali range of pH 7.5 to 9.

According to the present invention

- Direct commercialization/mass production can be realized by securing independent specialized technology through establishment of silk natural indigo yarn dyeing technology using cheese dyeing machine and linking natural dyeing-weaving-processing processes with a one-stop line between processes,

- It enables independent production of natural indigo dyed silk denim/denim-like material,

- By combining domestic silk weaving technology and natural dyeing technology, development of specialized materials and industrialization of natural dyeing can be realized.

- It is possible to make a breakthrough with a new item in the textile market where competition is intensifying by realizing the high-quality fabric applied with natural dyeing technology and creating a high-value-added product, and to preoccupy the overseas high-end material market.

1 is a flowchart schematically illustrating the process of a dyeing method according to the present invention.
2 is a photo of the bobbin shape (trapezoid, H) for a cheese dyeing machine.
Figure 3 shows a photograph of the process of the dyeing method according to the present invention.
4 is a real photograph of silk spun yarn (dye 1% and 3%) and silk filament yarn (dye 1%) dyed by the dyeing method according to the present invention.
5 is a real photograph of various silk yarns dyed by the dyeing method according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out the present invention. The embodiments of the present invention are provided in order to more completely explain the present invention to those of ordinary skill in the art. Accordingly, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

Throughout the specification of the present invention, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Throughout the specification of the present invention, when it is said that a step is located “on” or “before” another step, this means not only a case in which a step is in a direct time-series relationship with another step, but also a step of mixing after each step and Likewise, the order of two steps may include the same rights as in the case of an indirect time series relationship in which the time series order may change.

The terms "about", "substantially", etc. to the extent used throughout the specification of the present invention are used in or close to the numerical value when manufacturing and material tolerances inherent in the stated meaning are presented, and the present invention It is used to prevent unfair use by unconscionable infringers of the disclosure in which exact or absolute figures are mentioned to help understand. As used throughout this specification, the term “step of (to)” or “step of” does not mean “step for”.

The present invention relates to a method of dyeing silk yarn with natural indigo, and as shown in the process schematic diagram shown in FIG. 1, winding 100, refining 200, rewinding 300, reducing salt solution preparation 400, reduction It is characterized in that it includes the steps of bath preparation 500 , dyeing 600 , color development 700 , washing and soaping 800 , post-treatment 900 , and dehydration and drying 1000 .

Hereinafter, the present invention will be described in more detail based on the process diagram of FIG. 1 .

In the winding 100 process, a silk yarn is wound on a cheese bobbin (cone) using a cheese dyeing machine. The cheese dyeing machine is a commonly known tetra dyeing machine, and is a dyeing machine that dyes with a thread wound around a tubular core with a hole in it. The tubular core is called cheese bobbin or cheese cone, and after attaching the bobbin to the accessory (pole) inside the dyeing machine, it is put into the dyeing tank for dyeing. It is a device that evenly dyes the yarn wound on the cheese cone while repeating the cycle.

On the other hand, unlike the case of dyeing fibers such as cotton or wool, silk has different scales such as the size of the dye bath, the spacing between poles fixing the bobbin, the shape and length of the bobbin, and the weight of the yarn, so a cheese dyeing machine dedicated to silk is used. The bobbin of the general cheese dyeing machine uses a conical short one, but the bobbin used in the silk-only cheese dyeing machine has an elongated straight shape, the length is about 22-22.5cm, and the diameter is about 6-6.3cm (see FIG. 2). In Figure 2 (a) and (b), the short and thick bobbin (trapezoidal shape) of the general cheese dyeing machine, the long one is the silk-only bobbin (H-shape), and (c) is the silk-only bobbin for preventing the collapse of the four layers. It is a picture of a silk yarn wound at an angle.

In the cheese dyeing machine dedicated to silk, the winding weight per bobbin is 400 to 500 g. However, in the case of indigo dye, it can be adjusted up to at least 300 g to prevent internal and external deviation unevenness due to the dyeing characteristics. If the winding is less than that, productivity may decrease, and if it exceeds 500g, the surface of the yarn wound on the cheese cone may contact each other due to the shaking of the cheese cones on the poles inside the dyeing tank, which may cause unevenness.

In order to obtain a uniform quality of dyeing in cheese dyeing of silk yarn, physical conditions such as packing density, thickness (weight), pressure difference of sprayed dye solution, dye properties, and pump performance must be considered together in order to obtain uniform quality of dyeing. In particular, the packing density is a very important factor that directly affects the flow of the salt solution. If the density is high, salt spots appear prominently on the exterior, the uneven salting may become severe, and the drying efficiency may be reduced. It is necessary to select the appropriate winding conditions as shown in Table 1 to ensure smooth mobility by opening the movement space of dye molecules between the objects to be dyed wound on the bobbin in consideration of leveling to the inside and prevention of collapse of the four layers.

division speed load (tension) Starting load (tension) length (mt) weight shoulder 60/2 600 mt/min 4g 8g 12,000 to 15,000 mt 400-500g shoulder 120/2 750 mt/min 2g 5g 40,000~50,000 mt 400-500g 21/6 750 mt/min 18g 23g 30,800-38,500 mt 400-500g

The pretreatment process 200 is a process of removing impurities and sericin components unique to silk yarn from the surface, and includes refining and drying steps.

Silk yarn is composed of fibroin (75%), sericin (23%), alcohol precipitate (1.3%), ash (0.7%), etc. In order to utilize the characteristics of silk fiber and complete bleaching and dyeing, it is desirable to remove sericin and other impurities from the surface of the yarn and perform a preparatory process (refining) to improve the gloss and feel. SRK-1 (SNOGEN), a refining agent exclusively for silk, can be used. In this process, after refining, centrifugal dehydration is carried out and sufficiently dried for at least 15 hours in a hot air drying room.

The rewinding process 300 is a process of rewinding the refined and dried silk yarn to a cheese bobbin at an appropriate density. At this time, the winding conditions are the same as in the winding process 100 .

In the reduced salt solution preparation process 400, a reduced salt solution to be used in the subsequent dyeing process is prepared, and a reduced salt solution is prepared by mixing a natural indigo dye, a reducing agent, and an alkali agent. Natural indigo dye is a powder-type dye, for example, powder dye from India (dye content 40%) can be used. As a reducing agent, hydrosulfite (Na ₂ S ₂ O ₄ ) may be used. Hydrosulfite acts as a reducing agent for dyes and as an oxygen absorber. That is, it serves to reduce the insoluble indigo dye and convert it into a water-soluble leuco salt. The alkali range that makes the dye reducing power the most appropriate is about pH 11 to 12.5, and the alkali agent is caustic soda (NaOH) or sodium carbonate (Na ₂ CO ₃ ) may be used.

Indigo dyeing shows a difference in dyeability, especially depending on the amount of the alkali agent and the amount of the reducing agent.

In the reducing bath preparation step 500, the rewinding cheese bobbin is immersed in water in the cheese dyeing machine, and a predetermined leveling agent and a reducing agent are sequentially added to prepare a reducing bath in a weak acid or neutral range.

In the conventional indigo cheese dyeing method, an alkali agent such as sodium carbonate is added to a reducing bath to dye while maintaining strong alkalinity, but this is a general indigo dyeing method for cellulose (cotton). Silk fibers are damaged when dyed in a strong alkaline bath for a long time This is a concern and there is a problem that the dyeing property is also lowered. Therefore, it is necessary to maintain an appropriate pH condition for silk fibers. In the present invention, the reducing agent added to the reducing bath may be hydrosulfite. Hydrosulfite acts as a reducing agent and oxygen absorber. That is, the purpose of injecting a small amount of hydrosulfite into the reduction bath is to absorb oxygen present in the general water and to prevent the dye from being reoxidized by the oxygen present in the water by adding the reducing salt solution in the next process, thereby reducing the reducing power of the salt solution. is to maintain In addition, since the aqueous hydrosulfite solution is acidic, it can be added to general water to adjust the pH of the reducing bath to a slightly acidic or neutral range. The reason for controlling the pH of the reducing bath in the weak acidic or neutral range is that, when the reducing salt solution in the strong alkali range is mixed, it can be made into a neutral or weak alkali pH range suitable for silk dyeing.

On the other hand, a small amount of a leveling agent or a softening agent may be additionally added to the reducing bath. If the dyeing rate is too fast, a problem of uneven salt may occur. To prevent this, the dyeing rate is delayed and the surface tension is relieved to facilitate the mobility of the dye particles. As an example of the quencher of the present invention, a surfactant having affinity with the dye molecule or an ionic surfactant having good affinity with the yarn may be used, but it is not necessarily limited thereto, and a softener having the same function may be used. .

In the dyeing process 600, the reducing salt solution is added to the reducing bath to adjust the pH to a neutral or weak alkali range of 7.5 to 9, and then the salt solution is adsorbed under high pressure. Before inputting the reducing salt solution, the reducing bath is preferably heated to about 40°C. The pH control can be adjusted to an appropriate level by mixing a reducing salt solution, which is a strong alkali, and a reducing bath near neutral.

As mentioned above, for indigo dyeing of silk, pH control is important. Conventionally, it has been mainly carried out in a strong alkaline bath of pH 11 or higher, but in the case of silk fibers, damage to the appearance of the fibers and the removal and yellowing of the fibers due to the remaining alkali components may occur, so in the present invention, pH 7.5 to 9, preferably Let it be carried out in the range of 8-8.5 as a characteristic structure.

On the other hand, natural indigo dye contains natural impurities, and if these impurities are not filtered out of the reduced salt solution, severe uneven salting may occur during the dyeing process. Therefore, it is preferable to primarily filter impurities through a fiber filter or the like when the reducing salt solution is added.

In addition, if air is introduced by the bubbles generated during the dyeing process, uneven salt may be generated due to partial oxidation of the dye.

In this dyeing process, the internal salt solution of the cheese dyeing machine is sprayed from the inside to the outside for 5 to 6 minutes, and from the outside to the inside for 4 to 5 minutes. When spraying such a dye solution, the pressure difference between the inside and the outside is about 0.2 bar or less, but if it is too low, the dyeing inside the yarn may be insufficient.

In the color development process 700, the reduced dye dyed on the silk yarn is oxidized to cause color development. Preferably, hydrogen peroxide is added to oxidize the dye, and after hydrogen peroxide is added, the temperature is raised to a range of 40 to 50° C. to perform color development. The amount of hydrogen peroxide to be used is preferably about 1.5 to 2 g/l, and about 10 to 20% of the amount of hydrogen peroxide may be added as a peroxide stabilizer. After adding hydrogen peroxide at room temperature, the temperature is raised to perform color development.

When the color development is finished, a process 800 of removing residual impurities and unfixed dye is performed. At this time, an anion soaping agent and a predetermined scouring agent are added, and then soaked at 80 to 90° C. for 15 to 20 minutes, and then washed with hot water at 80° C. for 10 to 15 minutes. As a soaping agent, SR-144 (SNOGEN) can be used, and it is preferable to add about 1-1.5 g/L. As the refining agent, SRK-1 (SNOGEN) can be used, and about 0.3 to 0.5 g/l is preferable.

In the post-treatment process 900 , a softening agent and/or an antistatic agent are added to improve the yarn touch feeling as warp/weft yarns of the fabric and to prevent static electricity.

Finally, after centrifugal dehydration, it is preferable to go through a drying process 1000 of sufficiently drying for 24 hours or more by hot air drying.

All of the above processes are preferably carried out under a high pressure condition of 2 bar in a cheese dyeing machine.

Hereinafter, the indigo dyeing method of silk according to an embodiment of the present invention will be described in detail, whereby the characteristics of the dyeing method according to an embodiment of the present invention can be understood more specifically.

Example 1. Difference in dyeing properties according to the amount of alkali and reducing agent in reducing salt solution

To investigate the difference in dyeing properties depending on the amount of alkali and reducing agent added to the reducing salt solution, NaOH as an alkali agent and hydrosulfite as a reducing agent were added to 1% owf (on the weight of fabric) natural indigo dye as shown in the table below. Thus, a circular dye solution was prepared, and the result of dyeing using it was shown. The sample to be dyed was silk yarn 60/2 Nm, and Na ₂ S ₂ O ₄ 2% owf was added to the reducing bath. Staining was carried out at 50 °C for 20 minutes.

[ Table 2 ]

As in the above results, it was confirmed that when the pH of the reducing salt solution was less than the range of about pH 11 to 12.5, the leveling and color reproducibility were not satisfied.

Example 2. Difference in silk dyeing properties according to the pH of the reducing bath

The dyeing property to silk was measured by varying the pH of the reducing bath. The sample to be dyed was 60/2 Nm of silk yarn, and the reduced salt solution was prepared by adding 40wt% of natural indigo, 40~50wt% of hydrosulfite, and 10~20wt% of NaOH to change the pH (Test A = 10.6; Test B). = 12.5). _{Na 2} S ₂ O ₄ 2% owf was equally added to the reduction bath, _{and 2} wt% of Na 2 CO _{3 was added only to the comparative example.} Staining was carried out at 50 °C for 20 minutes.

[ Table 3 ]

As shown in the above results, it was confirmed that the degree of dyeing was more excellent in the case of the embodiment in which the pH of the reducing bath was near neutral (6.6).

In particular, in the case of Test B, even when the pH of the reducing salt solution is the same as 12.5, it was confirmed that the dyeing property was excellent in the case of the Example of the present invention in which the pH of the reducing bath was near neutral.

Example 3. Measurement of color fastness

Color fastness was measured for various silk yarns dyed by the dyeing method according to the present invention, and the results are shown as follows.

[ Table 4 ]

It was confirmed that excellent fastness was exhibited in both the spun yarn (shoulder yarn) and the filament yarn (refined yarn).

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. something to do.

Claims (5)

A winding process of winding silk yarn on a cheese bobbin using a cheese dyeing machine,
Pre-treatment process to remove impurities of silk yarn and sericin unique to silk yarn,
A re-winding process of rewinding the pre-treated silk yarn to a cheese bobbin at an appropriate density;
A process of accommodating the re-wound silk yarn in a cheese dyeing machine and preparing a reducing bath by adding water and a reducing agent;
After heating the reducing bath, a process of dyeing the dye solution on silk yarn by adding a reduced salt solution prepared by mixing a natural indigo dye, a reducing agent, and an alkali agent;
A process of uniformly oxidizing the dyed silk yarn to the inside by adding hydrogen peroxide to develop color;
A process of soaking the colored silk yarn and then washing it with hot water to remove residual impurities and unfixed dye;
post-treatment process, and
A method for natural indigo dyeing of silk, characterized in that it comprises a centrifugal dehydration and hot air drying process.
The method of claim 1,
The reduced salt solution is a natural indigo dyeing method of silk, characterized in that the alkaline pH of 11 to 12.5.
The method of claim 1,
The reducing bath is characterized in that the neutral or weakly acidic range of pH 5-7, natural indigo dyeing method of silk.
The method of claim 1,
The reducing agent added to the reducing bath is hydrosulfite (Na ₂ S ₂ O ₄ ), characterized in that the natural indigo dyeing method of silk.
The method of claim 1,
The process of dyeing the reduced salt solution is a natural indigo dyeing method of silk, characterized in that it is carried out in a neutral or weak alkali range of pH 7.5 to 9.

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