Indigo dyeing method

Abstract

To provide an indigo dyeing method that makes red dyeing possible using an indigo plant by preferential formation of indirubin as a red pigment rather than indigo as a blue pigment from the indigo plant, and that can also serve as means for producing indirubin.SOLUTION: A red solution is produced by heating fresh leaves and fresh stems of indigo in an acidic aqueous solution, and red dyeing is enabled by placing an object to be dyed into the red solution. Since the red pigment in the red solution is indirubin, the red solution is also usable as a supply source of indirubin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a red dye solution using blue plants and a method for producing an indirubin solution.

Background Art

[0002] Indigo dyeing is a traditional dyeing technique in which the dyed object is dyed with indigo, a blue pigment. However, among the pigments made from indigo, there is a very small amount of indirubin, a red pigment. Although indirubin has been studied as a pharmaceutical in addition to a pigment, it is very expensive as a reagent. In recent years, methods for producing a large amount of this indirubin by treating blue plants have been found, but these methods still produce more indigo, and the dyeing with the produced dye solution results in a purple color in which the blue pigment indigo and the red pigment are mixed.

[0003] In Patent Document 1, a method for producing indirubin, a red pigment, by cryopreservation treatment is known.

[0004] In Non-Patent Document 1, red-purple dyeing with indigo using alkali-treated silk cloth is known.

[0005] In Non-Patent Document 2, the production of indirubin, a red pigment, by heat treatment using citric acid is known.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007]

Non-Patent Document 1

Non-Patent Document 2

[0008] While prior art documents describe dyed fabrics as ranging from red to reddish-purple, all of these methods produce a large amount of indigo, resulting in a purple solution with low efficiency in producing the desired red pigment. Indirubin, the target pigment, is merely a by-product. This invention provides a red dye solution in which indirubin is the main product. [Means for solving the problem]

[0009] This invention improves the amount and proportion of indigo pigment produced by adding fresh indigo stems to the method described in Non-Patent Document 1, which involves heat-treating fresh indigo leaves with citric acid. This makes it possible to easily and inexpensively dye reddish-purple using indigo plants, and also provides indigo for use as a food additive, pharmaceutical, and dye. [Effects of the Invention]

[0010] In this invention, the amount and ratio of red pigment indirubin produced are improved to enable efficient reddish-purple dyeing using indigo plants.

[0011] Furthermore, it efficiently supplies indirubin, which can be used as a raw material for food additives, pharmaceuticals, and dyes. [Brief explanation of the drawing]

[0012] The dyed fabric was color-measured using a colorimeter, and numerical values ​​for the L* a* b* color system were obtained. The amount of stem was varied, and the results were obtained. The numerical values ​​of the color system were plotted on a graph.

[0013] The stems of the indigo plants freshly harvested were cut into pieces about 1 cm in length and placed in 30 g of water together with 6 g of citric acid. The solution was 80°C heated to About 10 minutes After heating, I finely chopped 3g of indigo plant leaves and heated them for 1 hour.

[0014] A 10 cm square silk cloth was immersed in the solution cooled to about room temperature for 1 hour, washed twice with about 300 g of water, wrung out, and then dried in a well-ventilated place. [Figure 1] It is a graph showing the relationship between the amount of stems and L*. [Figure 2] It is a graph showing the relationship between the amount of stems and a. [Figure 3] It is a graph showing the relationship between the amount of stems and b. [Embodiments for Carrying out the Invention]

[0015] Examples of the indigo dyeing method of the present invention are shown. The main steps of the present invention consist of a raw material collection step, a high-temperature treatment step, and a dyeing step. Raw material collection step

[0016] [Raw material collection step] The fresh leaves and stems of indigo plants are collected and washed with water. Preferably, indigo plants at the growth stage and freshly harvested are suitable as raw materials, and it is not desirable to leave time until the next step. [High-temperature treatment step] 9 g of indigo stems cut into pieces about 1 cm in length are placed in a solution in which 6 g of citric acid is dissolved in 30 g of water, and the temperature is raised to about 80°C. After about 10 minutes, 3 g of finely cut fresh indigo leaves are added and 1 hour heated to obtain a red solution. [Dyeing step] After the obtained red solution is cooled to room temperature, the cloth is dyed red by putting in a silk cloth. This dyeing does not come off with water. When the amount of stems in the previous step is reduced, the cloth may be dyed purple.

Claims

1. A method for producing a red dye solution by using the leaves and stems of fresh indigo plants in a weight ratio of 3:1 to 3:18, and heating them in an acidic aqueous solution with a pH of 3 or less at 80°C for 1 hour.

2. This method involves using the leaves and stems of fresh indigo plants in a weight ratio of 3:1 to 3:18, heating them in an acidic aqueous solution with a pH of 3 or less at 80°C for 1 hour, and then immersing the object to be dyed in the resulting red dye solution to achieve a red color.

3. A method for producing a red indirubin aqueous solution by using the leaves and stems of fresh indigo plants in a weight ratio of 3:1 to 3:18 and heat-treating them in an acidic aqueous solution with a pH of 3 or less at 80°C for 1 hour.

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