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 indigo plants and a method for producing an indirubin solution. [Background technology]

[0002] Indigo dyeing is a traditional dyeing technique in which the object is dyed with indigo, a blue pigment, but the pigment produced by indigo contains a very small amount of indirubin, a red pigment. In addition to being used as a pigment, indirubin has also been studied as a medicine, but it is very expensive as a reagent. In recent years, methods have been discovered to produce more indirubin by processing indigo plants, but these methods still produce more indigo, and the dye produced by the resulting dye solution is a purple color that is a mixture of indigo, a blue pigment, and red pigment.

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

[0004] Non-Patent Document 1 discloses a method for dyeing silk fabric treated with alkali into reddish purple with indigo.

[0005] Non-Patent Document 2 discloses the production of indirubin, a red pigment, by heat treatment using citric acid. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2005-336632

[0007] [Non-Patent Document 1] Satoshi Ushida and 1 other person, "Conditions for dyeing silk with reddish purple dyeing using fresh indigo leaves," Journal of the Japan Society of Home Economics, Vol. 49, No. 9, 1033-1036 (1998) [Non-patent document 2] Satoshi Ushida and two others, "Factors affecting the ratio of indigo to indirubin produced by acid hydrolysis of indican," Bull. Mukogawa Woman's Univ. Nat. Sci., 53, 37-44 (2005) Summary of the Invention [Problem to be solved by the invention]

[0008] It is stated that the cloth dyed by the method of the prior art document is dyed from red to reddish purple, but in any method, a large amount of indigo is produced, the solution is purple, the production efficiency of the target red pigment is low, and the target indirubin is a by-product. In the present invention, a red dye solution in which indirubin is the main product is provided. [Means for solving the problem]

[0009] The present invention adds indigo stems to the method of non-patent document 1, in which indigo leaves are heat-treated with citric acid, thereby improving the amount and rate of production of the red pigment indirubin, making it possible to easily and inexpensively dye reddish-purple with indigo plants, and also to provide indirubin, which can be used as a food additive, medicine, and dye. [Effects of the Invention]

[0010] In the present invention, efficient reddish-purple dyeing using indigo plants is made possible by improving the production amount and production rate of the red pigment indirubin.

[0011] It also efficiently supplies indirubin, which can be used as a raw material for food additives, medicines, and dyes. [Brief explanation of the drawings]

[0012] The dyed fabric was measured with a colorimeter to obtain the values ​​of the L* a* b* color system. The numerical values ​​of the color system were graphed.

[0013] Freshly harvested indigo plant stems were cut into pieces about 1 cm long and placed in 30 g of water with 6 g of citric acid. Approximately 80°C The temperature rises to Approximately 10 minutes After heating, Add 3g of finely chopped indigo leaves and cook for about 1 minute. Heated for hours.

[0014] Soak a 10cm square piece of silk cloth in the solution cooled to room temperature for 1 hour, then wash it twice with about 300g of water and wring it out. Dry in a well-ventilated place. [Figure 1] 1 is a graph showing the relationship between the amount of stems and L*. [Figure 2] 10 is a graph showing the relationship between the amount of stem and a. [Figure 3] 10 is a graph showing the relationship between the amount of stems and b. DETAILED DESCRIPTION OF THE INVENTION

[0015] This section describes an example of the indigo dyeing method of the present invention. The main steps of the method consist of a raw material collection step, a high-temperature treatment step, and a dyeing step.

[0016] Fresh leaves and stems of indigo plants are harvested and washed with water. Preferably, indigo plants should be harvested immediately after harvesting during the growing season, and it is not advisable to wait a long time before the next step. [High-temperature treatment process] 9g of indigo stem, cut into 1cm pieces 6g citric acid Put it into a solution dissolved in 30g of water, About 80°C The temperature rises. Approximately 10 minutes Then add 3g of finely chopped indigo leaves. Approximately 1 After heating for 1 hour a red solution is obtained. [Dyeing process] After cooling the resulting red solution to room temperature, add silk cloth to dye it red. This dye does not come off with water. of If the amount is reduced, the dye may turn purple.

[0017] The effects of the present invention will now be described. The weight ratio of the fresh leaves and stems of the indigo plant has a significant effect on the color tone of the resulting dye solution. In the case of leaves only, as shown in the colorimetry data in Figure 2, * The value is about +7.4, as shown in the color measurement data in Figure 3.* The value is about +2.3, and when the weight ratio of leaves to stems is 3:1, as shown in Figs. 2 and 3, * The value is about +19.5, b * The value increases to about +7.2, resulting in a bright red color. * value and b * It was confirmed that both values ​​increased and the effect saturated at around 3:12. Furthermore, it was found that sufficient reddish tones could be obtained even in the range up to 3:18. The dyeing method of the present invention makes it possible to obtain a stable red dye solution by adjusting the ratio of leaves to stems in this way.

Claims

1. This method involves heating raw indigo plant leaves and stems in an acidic aqueous solution with a pH of 3 or less for around an hour at a temperature that is not boiling, to produce a red dye solution.

2. The leaves and stems of raw indigo plants are heated in an acidic aqueous solution of pH 3 or less at a temperature just below boiling for about an hour, and the item to be dyed is then immersed in the resulting red dye solution to dye it red.

3. A method for producing a red indirubin aqueous solution by heating raw indigo plant leaves and stems in an acidic aqueous solution of pH 3 or less for about 1 hour at a temperature that is not boiling.

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