Method of Indigo Dyeing

Abstract

This invention provides an indigo dyeing method for partially dyeing fabric using a dye solution. [Solution] A method for dyeing with indigo, comprising the steps of: preparing a dye solution containing a pigment component including indigo and a binder resin; applying the dye solution to a fabric to be dyed; fixing the pigment component of the dye solution applied to the fabric to be dyed; reducing the pigment component of the dye solution fixed to the fabric to be dyed; and oxidizing the reduced pigment component. The pigment component is preferably a solid component extracted from indigo flowers produced during the indigo dyeing process of an indigo dye solution derived from natural indigo.

Description

Technical Field

[0001] The present invention is a method for indigo dyeing to dye a fabric to be dyed blue.

Background Art

[0002] Indigo dyeing is a traditional dyeing technique for fibers. Indigo, which is a blue pigment insoluble in water, is extracted from natural indigo or the like, and the indigo is reduced to leucoindigo soluble in water. The fabric is immersed in an indigo dyeing solution containing the leucoindigo to allow the leucoindigo to penetrate into the fibers, and the leucoindigo penetrated into the fibers is oxidized by air or the like to return to indigo, thereby dyeing the fibers blue. This indigo dyeing has a problem that the absorption rate of the dye into the fibers is low, and the color is deepened by immersing multiple times.

[0003] On the other hand, blue has a high commercial value as Japan blue, and it is required to color a unique blue other than the immersion method. In particular, it is required to easily attach a blue pattern to a part of the fabric. For example, Patent Document 1 discloses a method for producing precipitated blue that can be used as a pigment for paints. The method for producing precipitated blue in Patent Document 1 is a method for efficiently removing impurities derived from stems and leaves and excess slaked lime used until indigo is generated, and the content rate of indigo contained in the precipitated blue can be increased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The applicant prepared dye solutions using various precipitated indigo and pigments, including indigo, and attempted indigo dyeing by rubbing these solutions onto fabric. However, in each case, while it was possible to impart an indigo-like color to the fabric, the resulting color was far lighter than the color of the precipitated indigo or pigment used. In particular, when the dye solutions were rubbed onto fabric fixed to a Yuzen board, it was impossible to achieve the desired color at all. This invention was made to solve the above problems and aims to provide an indigo dyeing method for partially dyeing fabric using a dye solution. [Means for solving the problem]

[0006] The applicant diligently investigated this problem and found that by treating the fabric, which had been printed with the dye solution, in the order of reduction followed by oxidation, a distinctly deep indigo color could be imparted to the fabric. The reason why the color becomes more vivid after the reduction treatment is unclear, since the dye solution originally contains indigo, but it was found that the color does not appear by simply oxidizing the fabric printed with the dye solution, and that it is important to treat it in the order of reduction followed by oxidation. The applicant completed the present invention based on this finding.

[0007] The present invention provides a method for indigo dyeing, comprising the steps of: preparing a dye solution containing a pigment component including indigo and a binder resin; applying the dye solution to a fabric to be dyed; reducing the pigment component of the dye solution fixed to the fabric to be dyed; and oxidizing the reduced pigment component.

[0008] In the indigo dyeing method of the present invention, it is preferable that the dye solution is a liquid emulsion. The present invention relates to an indigo dyeing method, which preferably includes a step of fixing the pigment components of the dye solution applied to the fabric to be dyed before the step of reducing the pigment components. The present invention relates to an indigo dyeing method in which the step of applying the dye solution is preferably a step of applying the dye solution to the fabric to be dyed, which is fixed to a board. The present invention is preferably used for dyeing using a Yuzen board in the Itaba Yuzen dyeing method.

[0009] In the indigo dyeing method of the present invention, it is preferable that the indigo is derived from natural indigo. In particular, as a pigment component containing such naturally derived indigo, a solid component extracted from indigo flowers produced during the indigo vat preparation process of a naturally derived indigo dye solution is preferred. Conventionally, indigo flowers produced during the indigo vat preparation process of a naturally derived indigo dye solution are oxidized indigo components that appear before the fabric is immersed in the indigo dye solution and are discarded. However, it has been found that this solid component derived from indigo flowers has a high indigo component content and is therefore preferable in the indigo dyeing method of the present invention. Alternatively, as a pigment component containing naturally derived indigo, a solid component extracted from a liquid obtained by supplying air to a naturally derived indigo dye solution may be used. In this case, it is preferable because the pigment component can be produced. The present invention relates to a method for dyeing with indigo, wherein the indigo may be synthetic indigo. [Effects of the Invention]

[0010] The present invention provides a method for dyeing fabric using a dye solution to impart a deep indigo color to the fabric to be dyed. In particular, it is a method for dyeing a portion of the fabric to be dyed with a deep indigo color as a pattern. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1a is a photograph showing fabric dyed using the indigo dyeing method of Example 1, and Figure 1b is a photograph showing fabric dyed using the indigo dyeing method of Comparative Example 1. [Figure 2] A photograph of fabric dyed using the indigo dyeing method of the present invention. [Modes for carrying out the invention]

[0012] Next, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. The indigo dyeing method of the present invention comprises the steps of preparing a dye solution, applying the dye solution, reducing the pigment components, and oxidizing the pigment components. It is also preferable to perform a step of fixing the pigment components of the dye solution before the step of reducing the pigment components.

[0013] The process of preparing the dye solution involves preparing a dye solution containing a pigment component including indigo and a binder resin.

[0014] The pigment component must contain at least indigo. The indigo may be derived from natural indigo or it may be synthetically produced. Preferred pigment components containing indigo derived from natural indigo include solid components extracted from indigo flowers produced during the indigo dyeing process of natural indigo dye solution, or solid components extracted from a liquid obtained by supplying air to natural indigo dye solution. Natural indigo dye solution is a conventionally known method, and can be produced, for example, by preparing an extract containing components (indigo) extracted by soaking the stems and leaves of indigo-bearing plants in water, and then adding slaked lime, caustic soda, or wood ash lye to the extract (reduction) to prepare the indigo dye solution. The degree of indigo color development of these solid components varies depending on the amount of impurities, so the color can be changed by the extraction process. When using synthetic indigo, the indigo content in the pigment component can be increased, resulting in a more intense color. While there are no particular limitations on the binder resin, acrylic resins are preferred.

[0015] The dye solution is prepared by dispersing a solid component containing an indigo-containing dye component in a solvent. A liquid emulsion, particularly an aqueous emulsion, is preferred as the dye solution. Such a dye solution is prepared by adding a liquid emulsion containing a binder resin and a surfactant (for example, an aqueous emulsion containing an acrylic resin) to a liquid in which a solid containing an indigo-containing dye component is dispersed in a dispersant (for example, a tamol-based dispersant). Furthermore, it is preferable to add a separate flavoring agent (bleed prevention agent) (0.5-5% by weight) to the dye solution, depending on the fabric.

[0016] The step of brushing in the dye solution is a step of brushing in the dye solution onto the fabric to be dyed. Specifically, it is a step of applying, folding, or printing (pattern dyeing) the dye solution onto the fabric to be dyed by means such as rubbing or pressing. For example, there are methods such as applying a dye solution by placing a template with a pattern cut out on the fabric to be dyed, or inkjet printing by a machine. In particular, it is preferable to print the dye solution by applying a template to the fabric to be dyed fixed to a board (yuzen board). This method of brushing in the dye solution may be performed either by hand printing or machine printing.

[0017] The step of fixing the pigment component of the dye solution is a step of fixing the pigment component of the dye solution brushed onto the fabric to be dyed. For example, there are methods such as a steaming method of applying high-temperature steam to the fabric to be dyed onto which the dye solution has been printed, a baking method of drying the fabric to be dyed onto which the dye solution has been printed at a high temperature, or a natural drying method. After drying, it may be washed with water.

[0018] The step of reducing the pigment component is a step of reducing the pigment component of the dye solution fixed to the fabric to be dyed. Specifically, it is a step of immersing the fabric to be dyed onto which the dye solution has been fixed in a reducing agent. The reducing agent is not particularly limited, but for example, a hydrosulfite solution (pH 8 - 10) at 2 - 10% by weight (particularly 5 - 10% by weight) at 60°C - 80°C (particularly 70°C - 73°C) can be mentioned. The immersion time is preferably 1 minute - 10 minutes (particularly 4 minutes - 5 minutes). If the treatment is performed at a temperature higher than 80°C, there is a risk that the binder will dissolve and bleeding may occur.

[0019] The step of oxidizing the pigment component is a step of oxidizing the pigment component of the reduced dye solution again. Specifically, it is a step of washing the fabric to be dyed onto which the reduced dye solution has been fixed with water and then immersing it in an oxidizing agent. The oxidizing agent is not particularly limited, but when reducing with an alkaline hydrosulfite solution, an acidic solution is preferably mentioned. That is, it can be neutralized by immersing it in an acidic solution, and the pigment component of the dye solution is oxidized. Specifically, a method of immersing it in 1 - 5% (preferably 2 - 3%) acetic acid is preferably mentioned. Finally, washing with water completes the indigo dyeing.

[0020] The finished fabric can impart a dark blue color to the areas where the dye solution is brushed. Particularly, before the oxidation process, it exhibits a slightly greenish color, but by performing the oxidation process, the blue color can be developed all at once.

Example

[0021] 「Example 1」 A blue dye solution was prepared from the sukumo derived from natural indigo. The blue flowers formed on its surface were scooped up with ash lye or the like and dried solid content (manufactured by Konya Co., Ltd.) was prepared. This solid content derived from blue flowers was mixed with a dispersant (manufactured by Sano Co., Ltd., dye MD) at a weight ratio of 1:1, the concentration was adjusted with water, and then, a liquid emulsion (manufactured by Morimoto Co., Ltd., dye MW) was mixed to be 10%, and furthermore, an anti-crying agent (fragrance agent) was added to be about 1% by weight to adjust Dye Solution 1. Next, the above dye solution was brushed onto a white fabric fixed to a board, and then, it was cooled after baking at 100°C for 20 minutes and baked again at 100°C for 60 minutes to fix the pigment component of the dye solution to the fabric. At this time, the fabric exhibited a khaki color. Next, a 5% hydrosulfite solution at 70°C was prepared, the fabric was immersed for 5 minutes to reduce the pigment component, and then washed with water. At this time, the fabric had a slightly bluish tint but still exhibited a khaki color. Furthermore, a 3% acetic acid solution was prepared, and the fabric was immersed for 1 minute to oxidize the pigment component. By this treatment, the fabric exhibited a vivid blue color. A photograph of the fabric dyed by the method of Example 1 is shown in Fig. 1a.

[0022] 「Example 2」 Indigo blue powder (indigo derived from indigo) manufactured by Sano Co., Ltd. was prepared. This powder was mixed with a dispersant (manufactured by Sano Co., Ltd., dye MD) at a weight ratio of 1:1, and then, Dye Solution 2 was adjusted in the same manner as in Example 1, and a white fabric made of cloth was indigo-dyed using this Dye Solution 2. The indigo dyeing method of Example 2 also successfully dyed the fabric a vibrant indigo color. However, the blue in Example 2 was stronger than that of Example 1. This is thought to be due to a higher indigo content in the dye solution.

[0023] "Comparative Example 1" Using dried solids extracted from natural indigo sukumo (manufactured by Konya Co., Ltd.), the same dye solution 1 as in Example 1 was prepared. The dye solution 1 was then applied to a white cloth fabric fixed to a protective board, and the same baking process as in Example 1 was followed to fix the pigment components of the dye solution to the fabric. This was designated as Comparative Example 1. The fabric dyed using the method in Comparative Example 1 exhibited a khaki (bluish-brown) color. A photograph of the fabric dyed using this method is shown in Figure 1b.

[0024] "Comparative Example 2" Using dried solids extracted from natural indigo sukumo (manufactured by Konya Co., Ltd.), the same dye solution 1 as in Example 1 was prepared. The dye solution 1 was then applied to a white cloth fabric fixed to a Yuzen board, and the same baking process as in Example 1 was performed to fix the pigment components of the dye solution to the fabric. Next, without performing a reduction step, a 3% acetic acid solution was prepared, and the fabric was immersed for 1 minute to oxidize the pigment components. This is designated as Comparative Example 2. The fabric dyed using the method of Comparative Example 2 exhibited a khaki color that was almost identical to that of Comparative Example 1, although it had a slightly bluish tint.

[0025] The fabrics dyed using the methods of Comparative Examples 1 and 2 exhibited a khaki color. In contrast, the fabrics dyed using the methods of Examples 1 and 2 exhibited a vivid indigo color. Thus, even when using dye solutions containing different indigo-containing pigment components, a vivid indigo color could be imparted to the fabric by sequentially allowing reduction and oxidation reactions of the pigment components in the dye solution after the dye solution had been applied to the fabric. Figure 2 shows a photograph of fabric dyed using the Yuzen dyeing method of Example 1.

Claims

1. A process of preparing a dye solution containing a pigment component including indigo and a binder resin, The process of applying the dye solution to the fabric to be dyed, A step of reducing the pigment component of the dye solution fixed to the fabric to be dyed, The process comprises a step of oxidizing the reduced pigment component, Indigo dyeing method.

2. The indigo dyeing method according to claim 1, wherein the dye solution is a liquid emulsion.

3. Before the step of reducing the aforementioned pigment component, The process includes a step of fixing the pigment components of the dye solution that has been rubbed onto the fabric to be dyed. The indigo dyeing method according to claim 1.

4. The step of applying the dye solution is the step of applying the dye solution to the fabric to be dyed, which is fixed to a board. The indigo dyeing method according to claim 1.

5. The aforementioned indigo is indigo derived from natural indigo. The indigo dyeing method according to claim 1.

6. The aforementioned pigment component is a solid component extracted from indigo flowers produced during the indigo dyeing process of natural indigo dye. The indigo dyeing method according to claim 5.

7. The aforementioned indigo is a synthetic indigo. The indigo dyeing method according to claim 1.

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