CN113717542B

CN113717542B - Indigo dye vat liquid and preparation method and production device thereof

Info

Publication number: CN113717542B
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: 2024-01-05
Anticipated expiration: 2041-07-30
Also published as: CN113717542A

Abstract

The invention discloses an indigo dye vat liquid, a preparation method and a production device thereof, which comprise the following steps: mixing indigo dye, wetting agent and caustic soda solution to obtain indigo dye suspension mixed solution; mixing a solid hydrogen carrier and 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 indigo dye suspension mixture into a circulation reactor; the solid hydrogen carrier mixed solution is continuously pumped into a circulating reactor to be premixed with the indigo dye suspension mixed solution, and then flows out of a reaction bed after hydrothermal reaction at 25-80 ℃ through the reaction bed with the catalyst fixed thereon, and the circulation is continued until the reaction is finished. The preparation method of the indigo dye vat liquid has the advantages of compact process, controllable cost, small influence on environment, health and friendliness of operators, high concentration of pre-reduced leuco body mother liquid and good adaptability of the subsequent dyeing process.

Description

Indigo dye vat liquid and preparation method and production device thereof

Technical Field

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

Background

The jeans wear has been developed and evolved for over one hundred years, is standing on the stage of fashion wear, is especially popular with teenagers, and is not designed in the fashion front, more in various post-finishing processes, and realizes a unique and diversified style through the processing process.

Because of the characteristics of the indigo dye, the dye belongs to vat dye, is dyed by leuco after being vat, is naturally oxidized in air, and is repeatedly dyed and oxidized for a plurality of times, thus finishing the dyeing process of the indigo dye. However, in the conventional dyeing process of the indigo dye, the dyeing solution is firstly prepared according to the proportion among the indigo dye, sodium hydrosulfite and sodium hydroxide, but in the preparation process, since the sodium hydrosulfite and sodium hydroxide are dangerous chemicals, operators are easy to be dangerous in preparing the dyeing solution, particularly in preparing the dyeing solution, the dyeing solution is in an exothermic process, and the dyeing solution has heavier taste and seriously affects the physical health of operators. Meanwhile, sodium hydrosulfite is adopted as a reducing agent, a large amount of heat and toxic gases such as sulfur dioxide, hydrogen sulfide and the like can be released after the sodium hydrosulfite contacts with water, the physical health of workers is seriously affected, indigo mother liquor is prepared through a certain sequence during material opening, and the indigo mother liquor is prepared in a tank, so that inaccurate concentration is easily caused when sodium hydroxide or sodium hydrosulfite is added in the later stage.

With the development of society and the further improvement of living standard of people, the country puts forward higher requirements on environmental protection and energy conservation in the clothing production and manufacturing process, encourages the technical innovation of utilizing new energy, new technology and carbon reduction production to conform to the trend of the times of environmental protection and energy conservation. However, the sodium hydrosulfite is high in quality and low in cost, has intense reaction, generates toxic gas and has pungent smell, and does not accord with the novel green and environment-friendly sustainable development direction. However, jeans wear stands on fashion clothing stage, and although some students are researching a novel reducing agent to perform basic theoretical research, a dyeing method suitable for an actual indigo dye is not provided, and a novel hardware device and a novel hardware system for realizing high reproducibility and high reliability of a pre-reduction process are not provided for the actual dyeing method.

Indigo is the most widely used vat dye in the jean size dyeing industry, and the irreplaceable washing and rinsing style is the main reason why the equipment is favored and does not decline in the jean. The indigo dye must be reduced to a stable soluble leuco salt prior to dyeing, requiring the consumption of large amounts of reducing agents. Sodium dithionite (commonly known as "sodium hydrosulfite", hereinafter referred to as sodium hydrosulfite) is the most widely used reducing agent at present:

。

in addition, in recent years, hydrogen production by electrolysis of water and reduction of indigo dye by hydrogen are also becoming a new technological attempt trend:

。

the hydrogen production reduction method by water electrolysis has the advantage of environmental protection, and is increasingly valued in the industry as a sodium hydrosulfite alternative. However, the special equipment is expensive, the power consumption of hydrogen production is large, and the method is comprehensively popularized worldwide and meets the obstruction: the suppliers with the large-scale special equipment are far away from the production end, need special storage and transportation devices for long-distance transportation, and are not beneficial to the green production target of reducing the total carbon emission; although the miniaturized equipment can be flexibly arranged at the production end of a factory, the manufacturing cost is low, and the depreciation period of the equipment is long; meanwhile, the method has extremely high requirements on the safety production management of the workshop site.

Accordingly, the prior art is still in need of continuous improvement and development.

Disclosure of Invention

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

The technical scheme of the invention is as follows:

a preparation method of an indigo dye vat liquid comprises the following steps:

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

mixing a solid hydrogen carrier and 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 indigo dye suspension mixture into a circulation reactor;

the solid hydrogen carrier mixed solution is continuously pumped into a circulating reactor to be premixed with the indigo dye suspension mixed solution, then flows out of a reaction bed after the hydrothermal reaction of a reaction bed fixed with a catalyst at the temperature of 25-80 ℃, is premixed with the solid hydrogen carrier mixed solution continuously pumped into the circulating reactor, flows out of the reaction bed after the hydrothermal reaction of the reaction bed fixed with the catalyst at the temperature of 25-80 ℃, and continuously circulates until the reaction is finished.

The preparation method of the indigo dye vat liquid comprises the steps of adding a proper amount of steric hindrance agent into an indigo dye suspension mixed liquid;

the steric hindrance agent is a homopolymer or copolymer of polyacrylic acid, and the dosage is 1-5% of the mass percentage of the indigo dye.

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

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

The preparation method of the indigo dye vat liquid comprises the steps that the catalyst is a stable complex of copper or a porous polymer containing copper and a complex 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 to 3.5 times of the mass dosage of the indigo dye.

The preparation method of the indigo dye vat liquid comprises the steps that a solid hydrogen carrier is a boron hydride compound or a mixture of a plurality of boron hydride compounds; the solid hydrogen carrier is used in an amount ranging from 25 to 70% of the amount of indigo by mass.

The preparation method of the indigo dye vat liquid comprises the steps of carrying out hydrothermal reaction at 25-80 ℃ for 1-3 h.

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

The preparation method of the indigo dye vat liquid 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 vat liquid is between-900 and-1160 mV, and the pH value is between 11.5 and 13.6.

An indigo dye vat liquid, wherein the indigo dye vat liquid is prepared by the preparation method.

The device for producing the indigo dye vat 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 circular reaction;

the nitrogen pipeline is communicated with the closed reactor;

the reaction bed is arranged in a 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.

The beneficial effects are that: according to the preparation method of the indigo dye vat liquid, 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 circulation reaction. Each chemical can be quantitatively added, and has the characteristics of high conversion rate and small side reaction. Therefore, the invention has compact process, controllable cost, little influence on environment, health protection on operators, high concentration of pre-reduced leuco body mother liquor and good process adaptability of subsequent dyeing.

Drawings

FIG. 1 is a schematic diagram of a production apparatus of an indigo dye vat liquid according to the present invention.

Description of the 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 pipe; 11. a first pipe; 12. and a second pipe.

Detailed Description

The invention provides an indigo dye vat liquid, a preparation method and a production device thereof, and aims to make the purposes, technical schemes and effects of the invention clearer and more definite, and the invention is further described in detail below. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

In the description of the present invention, it should 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", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

The invention provides a preparation method of an indigo dye vat liquid, which comprises the following steps:

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

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

(2) Adding proper amount of steric hindrance agent into the indigo dye suspension mixture.

The steric hindrance agent may be a homopolymer or copolymer of polyacrylic acid (PAA); so that the suspended fine particles of the indigo dye remain in a highly dispersed state. The amount of the steric hindrance agent is generally 1-5% by mass of the indigo dye.

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

The solid hydrogen carrier may be a boron hydride compound or a mixture of boron hydride compounds such as lithium borohydride, potassium borohydride, calcium borohydride, and the like. The solid hydrogen carrier with good chemical stability in a normal state is used, the hydrogen release and reduction processes are synchronously completed in a closed space under the action of a specific catalyst, and the solid hydrogen carrier is isolated from oxygen in the air and contacted with the 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 dosage of the indigo mass; the total dosage of the caustic soda solution is 2.5 to 3.5 times of the dosage of the indigo dye by mass, wherein, the caustic soda solution in the mixed solution of the indigo dye suspension is 0.3 to 0.8 times of the dosage of the indigo dye by mass.

(4) And adding a proper amount of activating agent into the solid hydrogen carrier mixed solution.

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 activator is 5-20% of the solid hydrogen carrier by mass percent.

(5) And introducing nitrogen into the circulating reactor, and discharging air in the circulating reactor. The nitrogen gas may be supplied in a commercially available steel cylinder.

When the indigo dye vat liquid production device 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 polymer containing copper and its complex metal complexes, such as copper complexes of derivatives of 2-hydroxyphenyl groups. The catalyst has the advantages of high power conversion rate, stable property, reusability and no pollution to the pre-reduction working solution.

(6) And transferring the indigo dye suspension mixed liquor into a circulating reactor, and starting a first water pump to perform pressurized circulation until the reaction is finished.

(7) The solid hydrogen carrier mixed solution enters a circulating reactor through a second water pump, is premixed with the indigo dye suspension mixed solution at the feed inlet of the reaction bed 2 fixed with the catalyst, and then undergoes catalytic reaction through the reaction bed 2 fixed with the catalyst, and the flow is controlled to be 5-50 ml/min.

(8) At the hydrothermal reaction temperature of 25-80 ℃ (a heat exchanger is shown as a drawing 5), the first water pump keeps circulating, the second water pump continuously injects the mixed solution of the hydrogen carrier, 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 the reduced indigo leuco salt product can be obtained through the fluid mixed flow method circulation reaction. Each chemical can be quantitatively added, and has the characteristics of high conversion rate and small side reaction.

(10) The final product was tested for reduction potential, pH and indigo. Under normal conditions, the physical and chemical indexes of the indigo reducing solution must meet the following requirements to meet the basic production conditions: ORP is between-900 and-1160 mV, pH is between 11.5 and 13.6. The indigo value is a value obtained by measuring a value read by a photometer, which is the concentration of the leuco salt actually converted from the indigo dye, and varies depending on the indigo color, so long as the indigo value satisfies the desired 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 ℃.

Among them, the time of the hydrothermal reaction is preferably 1 to 3 hours, more preferably 2 hours.

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

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

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

(1) The solid hydrogen carrier with good chemical stability in a normal state is used, the hydrogen release and reduction processes are synchronously completed in a closed space under the action of a specific catalyst, and the solid hydrogen carrier is isolated from oxygen in the air and contacted with the 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, stable property, repeated use and no pollution to the pre-reduction working solution.

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

The invention also provides an indigo dye vat liquid, which is prepared by adopting the preparation method.

The quality of the indigo reduction mother liquor is directly related to the process constancy and reproducibility of jean yarn size dyeing production, and is intuitively reflected on various indexes such as fastness, color separation batch and the like. The invention can provide a new choice scheme for the innovation of jean size dyeing technology in the aspects of energy conservation and emission reduction and environmental protection as well as the internal quality of dyeing.

The invention also provides a production device of the indigo dye vat liquid, which comprises a closed reactor 1, a reaction bed 2 fixed with a catalyst, a conveying pipeline of solid hydrogen carrier mixed liquid, a first water pump 3, a second water pump 4, a heat exchanger 5 and a nitrogen pipeline 7, as shown in figure 1;

the discharge port of the closed reactor 1 is communicated with the feed port of the reaction bed 2 through a first pipeline, the discharge port of the reaction bed 2 is communicated with the feed port 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; pressurizing by a first water pump 3 to enable liquid to sequentially pass through the closed reactor 1, a first pipeline, the reaction bed 2 and a second pipeline for circular reaction;

the top of the closed reactor 1 is provided with a safety relief valve 6 which is kept in communication 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 solution into the first pipeline through a conveying pipeline of the solid hydrogen carrier mixed solution to participate in the circulating reaction.

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

The catalyst can be wrapped by a loose porous carrier 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 can not flow away along with the circulating fluid. For example, a cavity is arranged in the reaction bed 2, the catalyst is wrapped in polyester sponge, and then the catalyst is shaped by a steel wire mesh and fixed in the cavity of the reaction bed 2. The catalyst may be immobilized in a variety of ways and is not described in detail herein.

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

The invention is further illustrated by the following examples.

Example 1

A slurry dyeing continuous dyeing method of a chemical hydrogen carrier pre-vat 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 an indigo dye suspension mixed solution;

(2) 5g of a steric hindrance agent PAA (polyacrylic acid copolymer) are added;

(3) Uniformly dispersing 70g of solid boron hydride (potassium borohydride) in 300g of 30% caustic soda solution, and adding 200ml pure water to prepare a solid hydrogen carrier mixed solution;

(4) 10g of activator (lithium sulfate) was added;

(5) Transferring the mixed solution obtained in the step (1) and the step (2) into a closed reactor which is completely exhausted by nitrogen, starting a first water pump, and starting circulation;

(6) Adding the mixed solution obtained in the step (3) and the mixed solution obtained in the step (4) into fluid pumped into circulation working, wherein the flow is 5ml/min;

(7) Carrying out hydrothermal reaction in a reaction bed fixed with a catalyst (complex of 1- (2-hydroxyphenyl) -2-aza-3, 5-di (2-benzimidazole) pentane and copper), wherein the temperature is controlled at 55 ℃ and the reaction time is 2 hours;

(8) The obtained indigo dye vat liquid is transparent reddish brown liquid, the test indigo value is 134.6, the reduction potential is-1032 mM, and the pH value is 13.24.

Example 2

(1) Uniformly dispersing 100g of indigo dye, 2g of wetting agent (sodium arylsulphonate) 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 hindrance agent PAA (polyacrylic acid copolymer) are added;

(3) 68g of solid boron hydride compound (potassium borohydride) is uniformly dispersed in 300g of 30% caustic soda solution, and 200ml of purified water is added to prepare a solid hydrogen carrier mixed solution;

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

(7) Carrying out hydrothermal reaction in a reaction bed fixed with a catalyst (complex of 1- (2-hydroxyphenyl) -2-aza-3, 5-di (2-benzimidazole) pentane and copper), wherein the temperature is controlled at 60 ℃ and the reaction time is 1.6h;

(8) The obtained indigo dye vat liquid is transparent reddish brown liquid, the test 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 in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.

Claims

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

transferring the indigo dye suspension mixture into a circulation reactor;

continuously pumping the solid hydrogen carrier mixed solution into a circulating reactor to be premixed with the indigo dye suspension mixed solution, performing hydrothermal reaction at 25-80 ℃ through a reaction bed fixed with a catalyst, flowing out of the reaction bed, continuously pumping the solid hydrogen carrier mixed solution into the circulating reactor to be premixed with the solid hydrogen carrier mixed solution, performing hydrothermal reaction at 25-80 ℃ through the reaction bed fixed with the catalyst, and flowing out of the reaction bed, and continuously circulating until the reaction is finished;

the catalyst is a stable complex of copper or a porous polymer containing copper and a complex metal complex of copper;

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

the solid hydrogen carrier is a boron hydride compound or a mixture of boron hydride compounds; the dosage range of the solid hydrogen carrier is 25-70% of the dosage of the indigo mass;

the boron hydride compound is lithium borohydride, potassium borohydride and calcium borohydride;

the flow rate of the mixed solution of the solid hydrogen carrier is controlled to be 5-50 ml/min.

2. The method for preparing the indigo dye vat liquid according to claim 1, wherein a proper amount of a steric hindrance agent is added into the indigo dye suspension mixed liquid;

3. The method for preparing the indigo dye vat liquid according to claim 2, wherein an appropriate amount of activator is added into the solid hydrogen carrier mixed solution;

4. The method for preparing the indigo dye vat liquid according to claim 1, characterized in that the hydrothermal reaction temperature is 25-80 ℃ and the hydrothermal reaction time is 1-3 hours.

5. The method for preparing an indigo dye vat liquid according to claim 1, characterized by further comprising the steps of: