CN113717542A

CN113717542A - Indigo dye reducing solution and preparation method and production device thereof

Info

Publication number: CN113717542A
Application number: CN202110874338.XA
Authority: CN
Inventors: 王宗文; 胡永庚; 源满荣
Original assignee: Shanghai Chengxiang Industrial Development Co ltd; Advance Denim Co ltd
Current assignee: Shanghai Chengxiang Industrial Development Co ltd; Advance Denim Co ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-11-30
Anticipated expiration: 2041-07-30
Also published as: CN113717542B

Abstract

The invention discloses an indigo dye reducing solution, a preparation method and a production device thereof, comprising the following steps: mixing the indigo dye, a wetting agent and a caustic soda solution to obtain an indigo dye suspension mixed solution; mixing a solid hydrogen carrier and a caustic soda solution to prepare a solid hydrogen carrier mixed solution; introducing nitrogen into the circulating reactor, and discharging air in the circulating reactor; transferring the mixed solution of the indigo dye suspension into a circulating reactor; continuously pumping the solid hydrogen carrier mixed solution into a circulating reactor, premixing the solid hydrogen carrier mixed solution with the indigo dye suspension mixed solution, performing hydrothermal reaction on the mixed solution at a temperature of between 25 and 80 ℃ through a reaction bed fixed with a catalyst, and then flowing out of the reaction bed, and continuously circulating until the reaction is finished. The preparation method of the indigo dye reducing solution has the advantages of compact process, controllable cost, small influence on environment, human health friendliness of operators, high concentration of the pre-reduced leuco mother solution and good process adaptability of subsequent dyeing.

Description

Indigo dye reducing solution and preparation method and production device thereof

Technical Field

The invention relates to the field of indigo dyes, and mainly relates to an indigo dye reducing solution, a preparation method and a production device thereof.

Background

The jeans wear is developed and evolved for more than one hundred years, is erected on the stage of fashion wear, is particularly popular with teenagers, is not designed by the style at the front of fashion, is more a variable after-finishing process, and realizes a changeable unique style through a treatment process.

Due to the characteristics of the indigo dye, the dye belongs to a reducing dye, is reduced and then is dyed by a leuco body, is naturally oxidized in the air, and is dyed and oxidized repeatedly for a plurality of times to finish the coloring process of the indigo dye. However, in the conventional indigo dye dyeing process, a dyeing solution is firstly prepared according to the ratio of the indigo dye, sodium hydrosulfite and sodium hydroxide, but in the preparation process, since the sodium hydrosulfite and sodium hydroxide are dangerous chemicals, an operator is easy to have danger when preparing the dyeing solution, especially an exothermic process during preparation, and the taste is heavy, which seriously affects the physical health of the operator. Meanwhile, sodium hydrosulfite is used as a reducing agent, a large amount of heat and toxic gases such as sulfur dioxide and hydrogen sulfide are released after the sodium hydrosulfite is contacted with water, the physical health of workers is seriously influenced, indigo mother liquor is prepared in a certain sequence during cutting, and the indigo mother liquor is prepared in a cylinder tank, so that the concentration is easily inaccurate when sodium hydroxide or sodium hydrosulfite is added at the later stage.

With the development of society and the further improvement of living standard of people, the nation has higher requirements on environmental protection and energy conservation in the production and manufacturing process of clothes, and encourages technical innovation of new energy, new process and carbon reduction production to conform to the trend of the times of environmental protection and energy conservation. However, the sodium hydrosulfite is cheap and good in quality, but has violent reaction, generates toxic gas and has pungent smell, and does not accord with the direction of novel green environmental protection sustainable development. However, jeans wear is standing on the fashion wear stage, and although some scholars research novel reducing agents to conduct basic theoretical research, the jeans wear does not provide a dyeing method suitable for an actual indigo dye, and a new hardware device and a system for realizing high reproducibility and high reliability of a pre-reduction process aiming at the actual dyeing method.

Indigo is the most widely used vat dye in the denim dyeing industry, has no replaceable washing-back style, and is the main reason why the jeans are favored and durable. Indigo dyes must be reduced to stable soluble leuco salts before dyeing, requiring the consumption of large amounts of reducing agents. Sodium dithionite (commonly called sodium hydrosulfite, hereinafter sodium hydrosulfite) is the most widely used reducing agent at present:

。

in recent years, hydrogen production by electrolysis of water and reduction of indigo dye by hydrogen have also become a new technical attempt trend:

。

the reduction method for producing hydrogen by electrolyzing water has the advantage of environmental protection, and is increasingly paid attention by the industry as a substitute scheme of sodium hydrosulfite. But the special equipment is expensive, the power consumption of hydrogen production is large, and the hydrogen production is comprehensively popularized all over the world and is hindered: the supplier with the large-scale special equipment is far away from the production end, and needs a special storage and transportation device for long-distance transportation, which is not beneficial to reducing the green production target of total carbon emission; although the miniaturized equipment can be flexibly installed at the production end of a factory, the manufacturing cost is high, and the equipment depreciation period is long; meanwhile, the method has extremely high requirements on the safety production management of workshop sites.

Accordingly, there is a continuing need for improvements and developments in the art.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide an indigo dye reducing solution, a preparation method and a production device thereof, and aims to solve the problem that the existing electrolytic water hydrogen production reducing method has high requirements on equipment.

The technical scheme of the invention is as follows:

a preparation method of indigo dye reducing solution comprises the following steps:

mixing the indigo dye, a wetting agent and a caustic soda solution to obtain an indigo dye suspension mixed solution;

mixing a solid hydrogen carrier and a caustic soda solution to prepare a solid hydrogen carrier mixed solution;

introducing nitrogen into the circulating reactor, and discharging air in the circulating reactor;

transferring the mixed solution of the indigo dye suspension into a circulating reactor;

continuously pumping the solid hydrogen carrier mixed solution into a circulating reactor, premixing the solid hydrogen carrier mixed solution with the indigo dye suspension mixed solution, performing hydrothermal reaction on the mixed solution at a temperature of between 25 and 80 ℃ through a reaction bed fixed with a catalyst, then allowing the mixed solution to flow out of the reaction bed, premixing the mixed solution with the solid hydrogen carrier mixed solution continuously pumped, performing hydrothermal reaction on the mixed solution at a temperature of between 25 and 80 ℃ through the reaction bed fixed with the catalyst, allowing the mixed solution to flow out of the reaction bed, and continuously circulating until the reaction is finished.

The preparation method of the indigo dye reducing solution comprises the following steps of adding a proper amount of steric hindrance agent into indigo dye suspension mixed liquor;

the spatial position resisting agent is a homopolymer or a copolymer of polyacrylic acid, and the using amount of the spatial position resisting agent is 1-5% of the mass percentage of the indigo dye.

The preparation method of the indigo dye reducing solution comprises the steps of adding a proper amount of activating agent into a solid hydrogen carrier mixed solution;

the activating agent is soluble lithium salt, and the adding range of the activating agent is 5-20% of the solid hydrogen carrier by mass percent.

The preparation method of the indigo dye reducing solution comprises the following steps of (1) preparing a catalyst, wherein the catalyst is a stable complex of copper or a porous polymer containing copper and a composite metal complex thereof;

the mass concentration of the caustic soda solution is 30-50%; the total dosage of the caustic soda solution is 2.5-3.5 times of the mass dosage of the indigo dye.

The preparation method of the indigo dye reducing solution comprises the following steps of (1) preparing a solid hydrogen carrier by using a boron hydride or a mixture of a plurality of boron hydrides; the dosage range of the solid hydrogen carrier is 25-70% of the mass dosage of the indigo.

The preparation method of the indigo dye reducing solution comprises the following steps of carrying out hydrothermal reaction at a temperature of 25-80 ℃ for 1-3 hours.

The preparation method of the indigo dye reducing solution comprises the step of controlling the flow rate of pumping the solid hydrogen carrier mixed solution to be 5-50 ml/min.

The preparation method of the indigo dye reducing solution further comprises the following steps:

detecting the reduction potential value, the pH value and the indigo value of the final product;

the reduction potential value of the indigo dye reducing solution is between-900 mV and-1160 mV, and the pH value is between 11.5 mV and 13.6.

The indigo dye reducing solution is prepared by the preparation method of the indigo dye reducing solution.

A production device of indigo dye reducing liquid comprises a closed reactor, a reaction bed fixed with a catalyst, a conveying pipeline of solid hydrogen carrier mixed liquid, a first water pump, a second water pump, a heat exchanger and a nitrogen pipeline;

the discharge port of the closed reactor is communicated with the feed port of the reaction bed through a first pipeline, the discharge port of the reaction bed is communicated with the feed port of the closed reactor through a second pipeline to form a circulating reactor, and a first water pump is arranged in the first pipeline; pressurizing by a first water pump to enable liquid to sequentially pass through the closed reactor, the first pipeline, the reaction bed and the second pipeline for cyclic reaction;

the nitrogen pipeline is communicated with the closed reactor;

the reaction bed is arranged in the heat exchanger, and the heat exchanger provides heat exchange for the reaction bed;

the conveying pipeline of the solid hydrogen carrier mixed liquid is connected with the first pipeline, and the second water pump is arranged in the conveying pipeline of the solid hydrogen carrier mixed liquid.

Has the advantages that: according to the preparation method of the indigo dye reducing solution, the solid hydrogen carrier catalytic reduction reaction is carried out in a closed space isolated from air, and the reduced indigo leuco salt product can be obtained through the fluid mixed flow method cyclic reaction. Each chemical can be added quantitatively, and the method has the characteristics of high conversion rate and small side reaction. Therefore, the method has the advantages of compact process, controllable cost, small influence on the environment, human health friendliness for operators, high concentration of the pre-reduced leuco mother liquor and good process adaptability of subsequent dyeing.

Drawings

Fig. 1 is a schematic structural view of an apparatus for producing an indigo dye reducing solution of the present invention.

Description of reference numerals: 100. a bed panel; 1. a closed reactor; 2, a reaction bed; 3. a first water pump; 4. a second water pump; 5. a heat exchanger; 6. a safety relief valve; 7. a nitrogen gas pipeline; 11. a first conduit; 12. a second conduit.

Detailed Description

The present invention provides an indigo dye reducing solution, a preparation method and a production apparatus thereof, and the present invention is further described in detail below in order to make the objects, technical schemes and effects of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The invention provides a preparation method of indigo dye reducing solution, which comprises the following steps:

(1) uniformly dispersing a certain amount of indigo dye, a wetting agent and 30-50% caustic soda solution in mass concentration into purified water, and continuously stirring for 2-3 h to obtain an indigo dye suspension mixed solution.

The invention selects the fatty alcohol sulfate or aryl sulfonate anionic surfactant as the wetting agent, has the characteristics of good wetting property, low foaming power and stable alkali resistance, and is beneficial to fully wetting the indigo dye tiny particles. The addition amount of the wetting agent is generally 2-4% of the mass percent of the indigo dye.

(2) And adding a proper amount of steric inhibitor into the mixed solution of the indigo dye suspension.

The steric hindrance agent may be a homopolymer or copolymer of polyacrylic acid (PAA); so that the fine particles of the suspension of the indigo dye are maintained in a highly dispersed state. The dosage of the steric inhibitor is generally 1-5% of the mass percent of the indigo dye.

(3) Uniformly dispersing the solid hydrogen carrier in 30-50% by mass of caustic soda solution, and adding purified water to prepare a solid hydrogen carrier mixed solution.

The solid hydrogen carrier may be a borohydride or a mixture of borohydride compounds, such as lithium borohydride, potassium borohydride, calcium borohydride, and the like. The solid hydrogen carrier with good chemical stability under normal state is used, and under the action of a specific catalyst, the processes of hydrogen release and reduction are synchronously completed in a closed space, and the processes are isolated from and contacted with oxygen in the air, so that the reduction conversion rate of the indigo dye is improved.

In the invention, the dosage range of the solid hydrogen carrier is 25-70% of the mass dosage of the indigo; the total dosage of the caustic soda solution is 2.5-3.5 times of the mass dosage of the indigo dye, wherein the caustic soda solution in the mixed solution of the indigo dye suspension is 0.3-0.8 time of the mass dosage of the indigo dye.

(4) Adding proper amount of activator into the mixed solution of solid hydrogen carrier.

The activator may be a soluble lithium salt, such as lithium chloride or lithium sulfate, to increase the chemical activity of the hydrogen carrier. In the invention, the addition range of the activating agent is 5-20% of the solid hydrogen carrier by mass percent.

(5) Introducing nitrogen into the circulating reactor, and discharging air in the circulating reactor. Nitrogen gas may be supplied from commercially available cylinders.

When the production device of the indigo dye reducing solution is adopted for production, the reaction bed 2 fixed with the catalyst is connected with the closed reactor 1 to form a circulating reactor. The circulating reactor is a closed circulating reactor, so that air is prevented from entering and the quality of a product is prevented from being influenced.

The catalyst may be a stable complex of copper or a porous type polymer containing copper and its complex metal complexes, such as copper complexes of 2-hydroxyphenyl derivatives. The catalyst has the advantages of high work conversion rate, stable property, reusability and no pollution to pre-reduction working solution.

(6) And transferring the mixed solution of the indigo dye suspension into a circulating reactor, and starting a first water pump to pressurize and circulate until the reaction is finished.

(7) And (3) feeding the solid hydrogen carrier mixed solution into a circulating reactor through a second water pump, premixing the solid hydrogen carrier mixed solution with the indigo dye suspension mixed solution at a feed inlet of a reaction bed 2 fixed with a catalyst, and performing catalytic reaction through the reaction bed 2 fixed with the catalyst, wherein the flow rate is controlled to be 5-50 ml/min.

(8) And (3) under the hydrothermal reaction temperature of 25-80 ℃ (the heat exchanger is shown as figure 5), the first water pump keeps circulating, the second water pump continuously injects the mixed liquid of the hydrogen carriers, and the hydrothermal reaction is carried out for 1-3 h in a circulating state.

The solid hydrogen carrier catalytic reduction reaction is carried out in a closed space isolated from air, and a reduced indigo leuco salt product can be obtained through a fluid mixed flow method circulation reaction. Each chemical can be added quantitatively, and the method has the characteristics of high conversion rate and small side reaction.

(10) And detecting the reduction potential value, the pH value and the indigo value of the final product. Under the general conditions, the physicochemical indexes of the indigo reducing solution must meet the following requirements to meet the basic production conditions: the ORP value is between-900 mV and-1160 mV, and the pH value is between 11.5 mV and 13.6. The indigo value is the concentration at which the indigo dye is actually converted into the leuco salt, and is a value read by photometry, and the indigo value differs depending on the color of the indigo as long as the indigo value satisfies the required color.

(11) The pre-reduction process of the indigo dye mother liquor is completed.

Among them, the hydrothermal reaction temperature is preferably 40 to 80 ℃ and more preferably 60 ℃.

The time of the hydrothermal reaction is preferably 1 to 3 hours, and more preferably 2 hours.

Among them, the reduction potential is preferably-1000 to-1150 mV.

Among them, the pH value is preferably 12 to 13.5, and more preferably 13.2.

The method can completely replace the traditional indigo dye prereduction process by a sodium hydrosulfite method, and is also a low-cost alternative scheme of the reduction method for hydrogen production by water electrolysis:

(1) the solid hydrogen carrier with good chemical stability in a normal state is used, and hydrogen release and reduction processes are synchronously completed in a closed space under the action of a specific catalyst, and the processes are isolated from and contacted with oxygen in the air, so that the reduction conversion rate of the indigo dye is improved.

(2) The selected catalytic medium has high active conversion rate and stable property, can be repeatedly used and does not pollute the pre-reduction working solution.

(3) Greatly reduces the electrolyte content in the indigo dye reducing liquid medium and simultaneously reduces the energy consumption. Compared with sodium hydrosulfite, the TDS (total soluble solids) content is reduced by 45%; compared with the method for producing hydrogen by electrolyzing water, the TDS content is slightly higher than 10%, but the total energy consumption is reduced by 95%.

The invention also provides the indigo dye reducing solution which is prepared by the preparation method.

The quality of the indigo reduction mother liquor is good and bad, and is directly related to the process constancy and reproducibility of the denim yarn size dyeing production, and the indigo reduction mother liquor is visually embodied on various indexes such as fastness, color separation batches and the like. The invention provides a new selection scheme for the innovation of the jean pulp dyeing technology from the environmental protection significance of energy conservation and emission reduction and the inherent quality of dyeing.

The invention also provides a production device of the indigo dye reducing solution, which comprises a closed reactor 1, a reaction bed 2 fixed with a catalyst, a conveying pipeline of solid hydrogen carrier mixed solution, a first water pump 3, a second water pump 4, a heat exchanger 5 and a nitrogen pipeline 7, wherein the conveying pipeline is connected with the closed reactor 1;

the discharge hole of the closed reactor 1 is communicated with the feed hole of the reaction bed 2 through a first pipeline, the discharge hole of the reaction bed 2 is communicated with the feed hole of the closed reactor 1 through a second pipeline to form a circulating reactor, and a first water pump 3 is arranged in the first pipeline; a first water pump 3 pressurizes to enable liquid to sequentially pass through the closed reactor 1, a first pipeline, the reaction bed 2 and a second pipeline to carry out circulating reaction;

the top of the closed reactor 1 is provided with a safety relief valve 6 which is kept communicated with the atmosphere;

the nitrogen pipeline 7 is communicated with the closed reactor 1;

the reaction bed 2 is arranged in a heat exchanger 5, and the heat exchanger 5 provides heat exchange (heating or cooling) for the reaction bed 2;

the conveying pipeline of the solid hydrogen carrier mixed liquid is connected with the first pipeline, and the second water pump 4 is arranged in the conveying pipeline of the solid hydrogen carrier mixed liquid; the second water pump 4 pumps the solid hydrogen carrier mixed liquid into the first pipeline through a conveying pipeline of the solid hydrogen carrier mixed liquid to participate in the circulating reaction.

Preferably, the conveying pipeline of the mixed liquid of the solid hydrogen carriers is connected to a pipeline between the reaction bed 2 and the first water pump 3, so that the mixed liquid of the solid hydrogen carriers and the mixed liquid of the indigo dye suspension can be premixed and then enter the reaction bed 2, and then flow through the reaction bed 2 fixed with the catalyst, and hydrogen release of the hydrogen carriers and reduction reaction of carbonyl groups in molecular structures of the indigo dye can be synchronously completed.

The catalyst can be wrapped by loose porous carriers and then fixed in the reaction bed 2, so long as the fluid can enter the reaction bed 2, flow through the catalyst and finally flow out of the reaction bed 2, and the catalyst does not flow away with the circulating fluid. For example, a cavity is arranged in the reaction bed 2, the catalyst is wrapped in polyester sponge, and then shaped by a steel wire mesh and fixed in the cavity of the reaction bed 2. There are various ways of fixing the catalyst, which are not described herein.

The first water pump 3 and the second water pump 4 may be flow pumps with metering devices.

The present invention is further illustrated by the following specific examples.

Example 1

A pulp dyeing continuous dyeing method of chemical hydrogen carrier prereduced indigo dye comprises the following steps:

(1) uniformly dispersing 100g of indigo dye, 2g of wetting agent (fatty alcohol sodium sulfate) and 50g of 30% caustic soda solution in 100ml of purified water, and continuously stirring for 2 hours to prepare indigo dye suspension mixed liquor;

(2) 5g of a steric inhibitor PAA (polyacrylic acid copolymer) is added;

(3) uniformly dispersing 70g of solid borohydride (potassium borohydride) in 300g of 30% caustic soda solution, and supplementing 200ml of purified water to prepare a solid hydrogen carrier mixed solution;

(4) adding 10g of activator (lithium sulfate);

(5) transferring the mixed solution of the (1) and (2) into an airtight reactor which is exhausted by nitrogen, starting a first water pump, and starting to circularly work;

(6) adding the mixed solution of the (3) and (4) into the fluid pumped into the circulating work by a second water pump, wherein the flow rate is 5 ml/min;

(7) carrying out hydrothermal reaction in a reaction bed fixed with a catalyst (a complex of 1- (2-hydroxyphenyl) -2-aza-3, 5-bis (2-benzimidazole) pentane and copper), controlling the temperature at 55 ℃ and the reaction time for 2h;

(8) the obtained indigo dye reducing solution is transparent reddish brown liquid, the indigo value is tested to be 134.6, the reduction potential is-1032 mV, and the pH value is 13.24.

Example 2

(1) uniformly dispersing 100g of indigo dye, 2g of wetting agent (sodium arylsulfonate) and 50g of 30% caustic soda solution in 100ml of purified water, and continuously stirring for 2 hours to prepare an indigo dye suspension mixed solution;

(2) 5g of a steric inhibitor PAA (polyacrylic acid copolymer) is added;

(3) uniformly dispersing 68g of solid borohydride (potassium borohydride) in 300g of 30% caustic soda solution, and supplementing 200ml of purified water to prepare a solid hydrogen carrier mixed solution;

(4) 12g of activator (lithium chloride) was added;

(7) carrying out hydrothermal reaction in a reaction bed fixed with a catalyst (a complex of 1- (2-hydroxyphenyl) -2-aza-3, 5-bis (2-benzimidazole) pentane and copper), controlling the temperature at 60 ℃ and the reaction time for 1.6h;

(8) the obtained indigo dye reducing solution is transparent reddish brown liquid, the indigo value is 143.2, the reduction potential is-1016 mV, and the pH value is 13.10.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. The preparation method of the indigo dye reducing solution is characterized by comprising the following steps of:

2. The method for preparing a reducing solution of an indigo dye according to claim 1, wherein a suitable amount of a steric hindrance agent is added to the indigo dye suspension mixture solution;

3. The method for preparing a reducing solution of indigo dye according to claim 2, characterized in that an appropriate amount of an activating agent is added to the solid hydrogen carrier mixed solution;

4. The method for preparing an indigo dye reducing solution according to claim 1, wherein the catalyst is a stable complex of copper or a porous polymer containing copper and a complex metal complex thereof;

5. The method for preparing indigo dye reducing solution according to claim 1, wherein the solid hydrogen carrier is a borohydride or a mixture of borohydrides; the dosage range of the solid hydrogen carrier is 25-70% of the mass dosage of the indigo.

6. The method for preparing indigo dye reducing solution according to claim 1, wherein the hydrothermal reaction temperature is 25 ℃ to 80 ℃ and the hydrothermal reaction time is 1 to 3 hours.

7. The method for preparing a reducing solution of indigo dye according to claim 1, wherein the flow rate of pumping the solid hydrogen carrier mixed solution is controlled to be 5 to 50 ml/min.

8. The method of preparing an indigo dye-reducing solution according to claim 1, further comprising the steps of:

9. An indigo dye reducing solution characterized by being prepared by the method for preparing an indigo dye reducing solution according to any one of claims 1 to 8.

10. The production device of the indigo dye reducing solution is characterized by comprising a closed reactor, a reaction bed fixed with a catalyst, a conveying pipeline of solid hydrogen carrier mixed solution, a first water pump, a second water pump, a heat exchanger and a nitrogen pipeline;

the nitrogen pipeline is communicated with the closed reactor;