Method of Indigo Dyeing

Abstract

To provide an indigo dyeing method for partially dyeing a fabric using a dye solution. [Solution] An indigo dyeing method comprising the steps of preparing a dye solution containing color components including indigo and a binder resin, imprinting the dye solution onto a fabric to be dyed, fixing the color components of the dye solution imprinted onto the fabric to be dyed, reducing the color components of the dye solution fixed onto the fabric to be dyed, and oxidizing the reduced color components. The color components are preferably solid components extracted from indigo flowers that are produced during the indigo-building process of indigo dye solution derived from natural indigo.

Description

[Technical Field]

[0001] The present invention is an indigo dyeing method for dyeing a fabric in indigo blue. [Background technology]

[0002] Indigo dyeing is a traditional textile dyeing technique that involves extracting indigo, a water-insoluble indigo pigment, from natural indigo, reducing the indigo to water-soluble leucoidindigo, immersing the fabric in an indigo dye solution containing the leucoidindigo to allow it to soak into the fibers, and then oxidizing the leucoidindigo with air or other means to return it to indigo, thereby dyeing the fabric indigo blue. However, this indigo dyeing method has the problem of low dye absorption into the fabric, so the color is deepened by immersing the fabric multiple times.

[0003] Meanwhile, indigo, known as Japan Blue, has high commercial value, and there is a demand for methods other than the immersion method to achieve this unique indigo color. In particular, there is a demand for a method for easily applying an indigo pattern to a portion of fabric. For example, Patent Document 1 discloses a method for producing precipitated indigo that can be used as a paint pigment. The method for producing precipitated indigo in Patent Document 1 efficiently removes impurities derived from stems and leaves and excess slaked lime used to produce indigo, thereby increasing the indigo content in the precipitated indigo. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7244880 Summary of the Invention [Problem 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 printing these solutions onto fabric. However, in each case, although an indigo-based color could be imparted to the fabric, the resulting color was far lighter than the color of the precipitated indigo or pigment used. In particular, when these dye solutions were printed onto fabric fixed on a Yuzen board, the desired color could not be achieved at all. The present invention has been made to solve the above problems, and aims to provide an indigo dyeing method for partially dyeing fabric using a dye liquor. [Means for solving the problem]

[0006] The applicant has conducted extensive research into this issue and found that by subjecting fabric printed with a dye liquor to reduction and oxidation in that order, it is possible to impart a distinctly deep indigo color to the fabric. Because the dye liquor originally contains indigo, the reason why the reduction treatment results in a more vivid color is unclear. However, it was discovered that the color would not appear simply by oxidizing the fabric printed with the dye liquor, and that the reduction and oxidation treatments in that order are important. Based on this finding, the applicant has completed the present invention.

[0007] The indigo dyeing method of the present invention is characterized by comprising the steps of preparing a dye solution containing a pigment component including indigo and a binder resin, imprinting the dye solution onto a fabric to be dyed, reducing the pigment component of the dye solution fixed onto 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 liquid is a liquid emulsion. It is preferable that the indigo dyeing method of the present invention further includes a step of fixing the pigment components of the dye solution imprinted on the fabric to be dyed before the step of reducing the pigment components. In the indigo dyeing method of the present invention, the step of imprinting the dye liquid is preferably a step of imprinting the dye liquid onto the fabric to be dyed that is fixed to a board. The present invention is preferably used for Itaba Yuzen dyeing using a Yuzen board.

[0009] In the indigo dyeing method of the present invention, the indigo is preferably indigo derived from natural indigo. In particular, a preferred pigment component containing indigo derived from natural indigo is a solid component extracted from indigo flowers produced during the indigo-brewing process of indigo dyeing liquor derived from natural indigo. Conventionally, indigo flowers produced during the indigo-brewing process of indigo dyeing liquor derived from natural indigo are oxidized indigo components that appear before the fabric is immersed in the indigo dyeing liquor and are discarded. However, it has been found that the solid component derived from indigo flowers has a high indigo component content and is therefore preferred in the indigo dyeing method of the present invention. Alternatively, a solid component extracted from a liquid obtained by supplying air to an indigo dyeing liquor derived from natural indigo may be used as a pigment component containing indigo derived from natural indigo. This is preferable because it allows the pigment component to be produced. In the indigo dyeing method of the present invention, the indigo may be synthetic indigo. [Effects of the Invention]

[0010] The indigo dyeing method of the present invention is a method that can impart a deep indigo color to a dyed fabric using a dye solution. In particular, it is a method that can dye a part of the dyed fabric with a deep indigo color pattern. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1a is a photograph showing a fabric dyed with the indigo dyeing method of Example 1, and FIG. 1b is a photograph showing a fabric dyed with the indigo dyeing method of Comparative Example 1. [Figure 2] 1 is a photograph of a fabric dyed with Yuzen dye using the indigo dyeing method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, an embodiment of the present invention will be described, but the present invention is not limited to the following embodiment. The indigo dyeing method of the present invention includes the steps of preparing a dye solution, applying the dye solution, reducing the coloring matter, and oxidizing the coloring matter. It is also preferable to carry out a step of fixing the coloring matter in the dye solution before the step of reducing the coloring matter.

[0013] The step of preparing a dye solution is a step of preparing a dye solution containing a color component including indigo and a binder resin.

[0014] The pigment component contains at least indigo. The indigo may be derived from natural indigo or may be artificially produced synthetic indigo. Preferred examples of pigment components containing indigo derived from natural indigo include solid components extracted from indigo flowers that are produced during the indigo-making process of indigo dyeing liquor derived from natural indigo, or solid components extracted from a liquid obtained by supplying air to indigo dyeing liquor derived from natural indigo. Indigo dyeing liquor derived from natural indigo is a conventionally known method, and can be produced, for example, by steeping the stems and leaves of an indigo-bearing plant in water to produce an extract containing the component (indigo) extracted, and then adding (reducing) slaked lime, caustic soda, or wood lye to the extract to make indigo. Note that the color tone of these solid components can be changed by the extraction process, as the amount of impurities affects the degree of indigo color development. When synthetic indigo is used, the indigo content in the dye component can be increased, resulting in a deep color. The binder resin is not particularly limited, but an acrylic resin is preferred.

[0015] The dye solution is prepared by dispersing solid components containing indigo-containing pigments in a solvent. Liquid emulsions, particularly aqueous emulsions, are preferred. Such dye solutions are prepared by adding a liquid emulsion containing a binder resin and a surfactant (e.g., an aqueous emulsion containing an acrylic resin) to a liquid in which solid components containing indigo-containing pigments are dispersed in a dispersant (e.g., a tamol-based dispersant). It is preferable to add a fragrance (anti-bleeding agent) (0.5 to 5% by weight) to the dye solution separately depending on the fabric, etc.

[0016] The dyeing process is a process of printing the dye onto the fabric to be dyed. More specifically, it is a process of applying the dye onto the fabric to be dyed, rubbing it, or printing (pattern dyeing) it by pressing, etc. For example, the dyeing process can be performed by placing a stencil with a pattern cut out on the fabric to be dyed and printing the dye onto it, or by inkjet printing using a machine. In particular, it is preferable to print the dye by placing a stencil on the fabric to be dyed that is fixed on a board (Yuzen board). The dye solution may be applied by hand printing or machine printing.

[0017] The process of fixing the coloring matter of the dye solution is a process of fixing the coloring matter of the dye solution imprinted on the fabric to be dyed. For example, there are methods such as a steaming method in which high-temperature steam is applied to the fabric to be dyed after printing with the dye solution, a baking method in which the fabric to be dyed after printing with the dye solution is dried at high temperatures, and natural drying. After drying, the fabric may be washed with water.

[0018] The process of reducing the dye component is a process of reducing the dye component of the dye solution fixed on the fabric to be dyed. Specifically, it is a process of immersing the fabric to which the dye solution has been fixed in a reducing agent. The reducing agent is not particularly limited, but examples include a 2 to 10 wt % (particularly, 5 to 10 wt %) hydrosulfite solution (pH 8 to 10) at 60 to 80°C (particularly, 70 to 73°C). The immersion time is preferably 1 to 10 minutes (particularly, 4 to 5 minutes). If the treatment is performed at a temperature higher than 80°C, the binder may dissolve, causing bleeding.

[0019] The process of oxidizing the dye components is a process of re-oxidizing the dye components of the reduced dye liquor. Specifically, it is a process in which the dyed fabric on which the reduced dye liquor has been fixed is washed with water and then immersed in an oxidizing agent. There are no particular limitations on the oxidizing agent, but when reduction is performed using an alkaline hydrosulfite solution, an acidic solution is preferred. In other words, immersion in an acidic solution neutralizes the dye components of the dye liquor, oxidizing them. Specifically, a preferred method is immersion in 1 to 5% (preferably 2 to 3%) acetic acid. Finally, the indigo dyeing is completed by rinsing with water.

[0020] The finished fabric has a deep indigo color in the areas where the dye has been applied. Before the oxidation process, the fabric has a slightly greenish color, but once the oxidation process is carried out, the indigo color appears instantly. [Example]

[0021] "Example 1" Indigo dye solution was prepared from sukumo (sukumo) derived from natural indigo, and the indigo flowers that formed on the surface were scooped out with a lye skimming tool, and the solid matter (manufactured by Konya Co., Ltd.) was dried to prepare the solution. This solid matter derived from indigo flowers was mixed with a dispersant (Sano Corporation, dye MD) in a weight ratio of 1:1, the concentration was adjusted with water, and then a liquid emulsion (Morimoto Corporation, dye MW) was mixed in to make the concentration 10%, and then a tear-stopping agent (scenting agent) was added to make the concentration approximately 1% by weight to prepare dye solution 1. Next, the dye solution was applied to a white piece of fabric fixed to a board, then heated at 100°C for 20 minutes, cooled, and then steamed again at 100°C for 60 minutes (baking process) to fix the dye components of the dye solution to the fabric. At this point, the fabric had taken on a khaki color. Next, a 5% hydrosulfite solution at 70°C was prepared, and the fabric was immersed for 5 minutes to reduce the color components, and then washed with water. At this point, the fabric had acquired a slight bluish tinge, but still retained its khaki color. Furthermore, a 3% acetic acid solution was prepared and the fabric was immersed for 1 minute to oxidize the pigment components, resulting in a vivid indigo blue color on the fabric. A photograph of the fabric dyed by the method of Example 1 is shown in Figure 1a.

[0022] "Example 2" Indian indigo powder (indigo derived from Indian indigo) was prepared by Sano Co., Ltd. This powder was mixed with a dispersant (dye MD, manufactured by Sano Co., Ltd.) in a weight ratio of 1:1, and then dye solution 2 was prepared in the same manner as in Example 1. White fabric was indigo dyed with this dye solution 2. The indigo dyeing method of Example 2 also allowed for the fabric to be dyed a vivid indigo color. However, Example 2 produced a stronger blue color than Example 1. This is thought to be due to the higher indigo content in the dye solution.

[0023] "Comparative Example 1" The same dye solution 1 as in Example 1 was prepared using dried solids extracted from sukumo (made by Konya Co., Ltd.) derived from natural indigo, and dye solution 1 was imprinted onto a white cloth fabric fixed to a board. After that, it was subjected to the same baking process as in Example 1 to fix the color component of the dye solution to the fabric. This is referred to as Comparative Example 1. The fabric dyed by the method of Comparative Example 1 exhibited a khaki color (blue-brown). A photograph of the fabric dyed by this method is shown in Figure 1b.

[0024] "Comparative Example 2" The same dye solution 1 as in Example 1 was prepared using dried solids extracted from sukumo (produced by Konya Co., Ltd.) derived from natural indigo. Dye solution 1 was then imprinted onto a white cloth fabric fixed to a yuzen board, followed by the same baking process as in Example 1 to fix the dye components of the dye solution to the fabric. Next, without carrying out the reduction step, a 3% acetic acid solution was prepared and the fabric was immersed for 1 minute to oxidize the dye components. This is Comparative Example 2. The fabric dyed by the method of Comparative Example 2 had a slight bluish tint, but was still a khaki color that was almost the same as that of Comparative Example 1.

[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. Even when dye solutions containing different indigo-containing pigment components were used, a vivid indigo color could be imparted to the fabric by applying the dye solution to the fabric and then subjecting the pigment components of the dye solution to a reduction reaction and then an oxidation reaction. FIG. 2 shows a photograph of fabric dyed using the method of Example 1.

Claims

1. A step of preparing a dye solution comprising a solid extracted from a color component containing indigo or an indigo dye solution derived from natural indigo, a dispersant, an aqueous emulsion of a binder resin, and optionally water; A step of printing the dye liquid onto a fabric to be dyed; A step of fixing the pigment component of the dye solution imprinted on the fabric to be dyed; A step of immersing the fabric to be dyed in a hydrosulfite solution to reduce the dye component of the dye solution fixed on the fabric to be dyed; and washing the dyed fabric with water and immersing it in an acidic solution to oxidize the reduced dye component. Indigo dyeing method.

2. A step of preparing a dye solution comprising a solid extracted from a color component containing indigo or an indigo dye solution derived from natural indigo, a dispersant, an aqueous emulsion of a binder resin, a fragrance, and optionally water; A step of printing the dye liquid onto a fabric to be dyed; A step of fixing the pigment component of the dye solution imprinted on the fabric to be dyed; A step of immersing the fabric to be dyed in a hydrosulfite solution to reduce the dye component of the dye solution fixed on the fabric to be dyed; and washing the dyed fabric with water and immersing it in an acidic solution to oxidize the reduced dye component. Indigo dyeing method.

3. The step of imprinting the dye solution is a step of imprinting the dye solution onto the fabric to be dyed fixed to a board. The indigo dyeing method according to claim 1 or 2.

4. The indigo is derived from natural indigo. The indigo dyeing method according to claim 1 or 2.

5. The pigment component is a solid component extracted from indigo flowers that are produced during the indigo dyeing process of indigo dyeing liquid derived from natural indigo. The indigo dyeing method according to claim 4.

6. The indigo is a synthetic indigo. The indigo dyeing method according to claim 1 or 2.

Images