Cellulose fibers and method for dyeing the same

Abstract

The embodiment of the application discloses a cellulose fiber and a dyeing method thereof. The method comprises the following steps: mixing strong alkali and sodium dithionite in concentrated ammonia water to obtain a reduction solution; adding vat dyes to the reduction solution, reducing for 10-60 minutes under the environment of 30-50 DEG C, and cooling to room temperature to obtain a vat dyeing solution; adding liquid ammonia to the vat dyeing solution to obtain a liquid ammonia vat dyeing solution; and immersing cellulose fiber into the liquid ammonia vat dyeing solution for dyeing, and then carrying out oxidation and soaping in air to obtain dyed cellulose fiber. The vat dyeing solution prepared by using concentrated ammonia water can be easily mixed with liquid ammonia in any proportion, and the liquid ammonia vat dyeing solution containing different water contents can be easily prepared. In addition, the presence of water in the liquid ammonia vat dyeing solution can maintain the reduction state of the vat dyes in the dyeing process, thereby avoiding the problem that the vat dyes are oxidized and the fiber is not dyed through.

Description

Technical Field

[0001] This application relates to the field of dyeing and finishing technology, and in particular to a cellulose fiber and a dyeing method thereof. Background Technology

[0002] Indigo dye is a vat dye, and cotton yarns and fabrics dyed with it are mainly used in denim clothing. Indigo vat dye is insoluble in water. During the dyeing process, it needs to be reduced to soluble sodium indigo leucoate in the presence of sodium hydrosulfite and an alkali agent. This soluble sodium indigo leucoate then penetrates the cotton fibers and is subsequently oxidized back to indigo vat dye, which is then fixed within the fibers. Because the dyed material comes into contact with oxygen in the air during the dyeing process, the soluble sodium indigo leucoate is oxidized by the oxygen in the air before it has fully penetrated, and is fixed on the fiber surface. Especially when dyeing yarn with indigo, the indigo vat dye adheres to the yarn surface, forming ring dye. Therefore, indigo vat dye requires multiple dyeing processes to fully penetrate cotton yarn, meaning multiple reduction and oxidation cycles are needed, increasing production costs. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a cellulose fiber and its dyeing method, aiming to solve the problems of multiple dyeing processes and high costs caused by the multiple dyeing steps in the dyeing of indigo vat dye in the prior art.

[0004] In a first aspect, this application provides a method for dyeing cellulose fibers, comprising:

[0005] A strong alkali and sodium hydrosulfite are mixed in concentrated ammonia water to obtain a reducing solution;

[0006] The vat dye is added to the reducing solution and reduced at 30-50°C for 10-60 minutes. Then, it is cooled to room temperature to obtain the vat dye solution.

[0007] Liquid ammonia is added to the reducing dye solution to obtain a liquid ammonia reducing dye solution;

[0008] Cellulose fibers are immersed in the liquid ammonia reducing dye solution for dyeing, and then oxidized and soaped in the air to obtain dyed cellulose fibers.

[0009] Furthermore, in the dyeing method for the cellulose fibers, the ammonia content in the concentrated ammonia solution is 20-30%.

[0010] Furthermore, in the dyeing method for cellulose fibers, the concentration of the strong alkali dissolved in the concentrated ammonia solution is 10-60 g / L; or / and

[0011] The concentration of sodium hydrosulfite dissolved in the concentrated ammonia water is 80-200 g / L.

[0012] Furthermore, in the dyeing method for cellulose fibers, the concentration of vat dye in the vat dyeing solution is 30-60 g / L; or / and

[0013] The vat dyes include indigo vat dyes.

[0014] Furthermore, in the dyeing method for cellulose fibers, the volume ratio of the reducing dye solution to the liquid ammonia is (1-5):(15-19).

[0015] Furthermore, in the dyeing method for the cellulose fibers, the cellulose fibers include one or more of cotton fibers, linen fibers, viscose fibers, and modal fibers.

[0016] Furthermore, in the dyeing method for cellulose fibers, the morphological structure of the cellulose fibers can be any one of loose fiber, yarn, or fabric.

[0017] Furthermore, in the dyeing method for the cellulose fibers, the dyeing includes either immersion dyeing or pad dyeing.

[0018] Furthermore, in the dyeing method for the cellulose fibers, the dyeing time is 1-10 minutes.

[0019] Secondly, this application also provides a cellulose fiber, which is prepared by the dyeing method of the cellulose fiber described in the first aspect.

[0020] The cellulose fiber and dyeing method provided in this application utilize a vat dyeing liquor prepared with concentrated ammonia, which can be easily mixed with liquid ammonia in any proportion. This facilitates the preparation of vat dyeing liquors with varying moisture content. The presence of moisture in the vat dyeing liquor creates a strongly alkaline environment, which helps maintain the reduced state of the vat dye during dyeing and prevents oxidation of the vat dye, thus ensuring thorough dyeing. Furthermore, the vat dyeing liquor can quickly penetrate the fiber, enabling rapid dyeing and saving production time. Simultaneously, the small amount of moisture in the liquid ammonia has a mercerizing and decrystallizing effect on the fiber. During the dyeing process, the amorphous region of the fiber increases, improving the dye uptake rate; dyeing and mercerizing are completed simultaneously. The small amount of moisture in the vat dyeing liquor also contributes to the stability and reproducibility of the dyeing effect. Finally, the entire dyeing process uses less water and less dye / chemical, and the vat dye and liquid ammonia are easily recyclable. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0022] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] To address the shortcomings of existing technologies, this application provides a method for dyeing cellulose fibers, comprising:

[0026] A strong alkali and sodium hydrosulfite are mixed in concentrated ammonia water to obtain a reducing solution;

[0027] The vat dye is added to the reducing solution and reduced at 30-50°C for 10-60 minutes. Then, it is cooled to room temperature to obtain the vat dye solution.

[0028] Liquid ammonia is added to the reducing dye solution to obtain a liquid ammonia reducing dye solution;

[0029] Cellulose fibers are immersed in the liquid ammonia reducing dye solution for dyeing, and then oxidized and soaped in the air to obtain dyed cellulose fibers.

[0030] Specifically, this application involves fully dissolving and reducing the indigo vat dye in concentrated ammonia water using a strong alkali, sodium hydrosulfite, and indigo vat dye, and then adding the solution to liquid ammonia to complete the indigo liquid ammonia reduction dyeing solution. The yarn is then immersed in the indigo liquid ammonia reduction dyeing solution for dyeing, followed by oxidation in the air and soaping. This achieves the effect of achieving indigo penetration and dark-colored yarn in a single dyeing process.

[0031] The cellulose fiber dyeing method provided in this application uses a vat dyeing solution prepared with concentrated ammonia water, which can be easily mixed with liquid ammonia in any proportion to easily prepare liquid ammonia vat dyeing solutions with different moisture contents. At the same time, the presence of water in the liquid ammonia vat dyeing solution creates a strongly alkaline condition, which is beneficial to maintaining the reduced state of the vat dye during dyeing and avoids the problem of the vat dye being oxidized during the dyeing process, resulting in the fiber not being fully dyed.

[0032] Furthermore, liquid ammonia reducing dye liquor can quickly penetrate into the fiber, enabling rapid dyeing and saving production time. Simultaneously, the small amount of water in the liquid ammonia reducing dye liquor has a mercerizing and decrystallizing effect on the fiber. During the dyeing process, the amorphous region of the fiber increases, improving the dye uptake rate; that is, dyeing and mercerizing are completed simultaneously. Moreover, the small amount of water in the liquid ammonia reducing dye liquor contributes to the stability and reproducibility of the dyeing effect. Finally, the entire dyeing process uses less water and less dye and chemical, and the vat dye and liquid ammonia are easily recycled.

[0033] In some embodiments, the ammonia content in the concentrated ammonia solution is 20-30%. Preferably, the ammonia content in the concentrated ammonia solution is 25%.

[0034] In some embodiments, the concentration of the strong alkali dissolved in concentrated ammonia water is 10-60 g / L. Preferably, the concentration of the strong alkali dissolved in the concentrated ammonia water is 40 g / L.

[0035] In some embodiments, the concentration of sodium hydrosulfite dissolved in concentrated ammonia water is 80-200 g / L. Preferably, the concentration of sodium hydrosulfite dissolved in concentrated ammonia water is 120 g / L.

[0036] In some embodiments, the concentration of vat dye in the vat dyeing solution is 30-60 g / L. Preferably, the concentration of vat dye in the vat dyeing solution is 40 g / L.

[0037] In some embodiments, the vat dyes mentioned in this application are preferably indigo vat dyes.

[0038] In some embodiments, the volume ratio of the reducing dye solution to the liquid ammonia is (1-5):(15-19). Preferably, the volume ratio of the reducing dye solution to the liquid ammonia is 2:18.

[0039] In some embodiments, the cellulose fiber includes one or more selected from cotton fiber, linen fiber, viscose fiber, and modal fiber. Cotton fiber is preferred as the cellulose fiber.

[0040] In some embodiments, the morphological structure of the cellulose fiber includes any one of loose fiber, yarn, or fabric. Preferably, the morphological structure of the cellulose fiber is yarn.

[0041] In some embodiments, the dyeing includes either immersion dyeing or pad dyeing. Immersion dyeing is the preferred dyeing method mentioned in this application.

[0042] In some embodiments, the staining time is 1-10 minutes. Preferably, the staining time is 3 minutes.

[0043] In some embodiments, the strong alkali includes one or more of sodium hydroxide and potassium hydroxide, and the sodium dithionite includes sodium dithionite.

[0044] In some embodiments, this application also provides a cellulose fiber prepared by the dyeing method of the cellulose fiber described above.

[0045] The following examples illustrate the dyeing method of cellulose fibers according to embodiments of the present invention.

[0046] Example 1

[0047] Slowly add 1-6g of NaOH to 100mL of concentrated ammonia water (25% ammonia content), then add 12g of sodium hydrosulfite. After it is fully dissolved, add 4g of indigo vat dye. While stirring, raise the temperature to 40℃ and keep it at that temperature for 30 minutes to fully reduce the indigo vat dye. Cool to room temperature to complete the preparation of 40g / L indigo ammonia water reducing dye solution.

[0048] Take 2 mL of each of the 40 g / L indigo ammonia reducing dye solutions containing different NaOH contents, then add liquid ammonia to make 20 mL. Immerse 1 g of cotton yarn in the dye solution for 3 minutes, then remove it and oxidize it in the air for 10 minutes. Finally, wash it with soap and let it air dry.

[0049] The K / S values ​​of the dyed yarns were measured, and the results are listed in Table 1. Cross-sections of the dyed fibers observed under an optical microscope showed uniform dye penetration in all cases.

[0050] Table 1. K / S values ​​of yarns after dyeing with different NaOH contents (40 g / L indigo ammonia reducing dye solution)

[0051] NaOH content (g) 1 2 3 4 5 6 K / S value 8.6 11.2 12.4 13.5 12.7 12.3

[0052] Example 2

[0053] Slowly add 4g of NaOH to 100mL of concentrated ammonia water (25% ammonia content), then add 8-20g of sodium hydrosulfite. After it is fully dissolved, add 4g of indigo vat dye. While stirring, raise the temperature to 40℃ and keep it at that temperature for 30 minutes to fully reduce the indigo vat dye. Cool to room temperature to complete the preparation of 40g / L indigo ammonia water reducing dye solution.

[0054] Take 2 mL of each of the 40 g / L indigo ammonia reducing dye solutions containing different amounts of sodium hydrosulfite, then add liquid ammonia to make 20 mL. Immerse 1 g of cotton yarn in the dye solution for 3 minutes, then remove it and oxidize it in the air for 10 minutes. Finally, wash it with soap and let it air dry.

[0055] The K / S values ​​of the dyed yarns were measured, and the results are listed in Table 2. Cross-sections of the dyed fibers observed under an optical microscope showed uniform dye penetration.

[0056] Table 2. K / S values ​​of yarns dyed with different sodium hydrosulfite contents

[0057] Sodium hydrosulfite content (g) 8 10 12 14 16 20 K / S value 8.9 11.3 13.5 13.1 12.8 12.2

[0058] Example 3

[0059] Slowly add 4g of NaOH to 100mL of concentrated ammonia water (25% ammonia content), then add 12g of sodium hydrosulfite. After it is fully dissolved, add 4g of indigo vat dye. While stirring, raise the temperature to 40℃ and keep it at that temperature for 30 minutes to fully reduce the indigo vat dye. Cool to room temperature to complete the preparation of 40g / L indigo ammonia water reducing dye solution.

[0060] Take 2 mL of 40 g / L indigo ammonia reducing dye solution, then add liquid ammonia to 20 mL. Immerse 1 g of cotton yarn in the dye solution for 1-10 minutes, then remove it and oxidize it in the air for 10 minutes. Finally, wash it with soap and let it air dry.

[0061] The K / S values ​​of the dyed yarns were measured, and the results are listed in Table 3. Cross-sections of the dyed fibers observed under an optical microscope showed uniform dye penetration in all cases.

[0062] Table 3. K / S values ​​of yarn after dyeing at different times

[0063]

[0064]

[0065] Example 4

[0066] Slowly add 4g of NaOH to 100mL of concentrated ammonia water (25% ammonia content), then add 12g of sodium hydrosulfite. After it is fully dissolved, add 4g of indigo vat dye. While stirring, raise the temperature to 40℃ and keep it at that temperature for 30 minutes to fully reduce the indigo vat dye. Cool to room temperature to complete the preparation of 40g / L indigo ammonia water reducing dye solution.

[0067] Take 1-5 mL of 40 g / L indigo ammonia reducing dye solution containing different amounts of sodium hydrosulfite, add liquid ammonia to 20 mL, immerse 1 g of cotton yarn in the dyeing solution for 13 minutes, remove it, oxidize it in the air for 10 minutes, then wash it clean with soap and air dry.

[0068] The K / S values ​​of the dyed yarns were measured, and the results are listed in Table 4. Cross-sections of the dyed fibers observed under an optical microscope showed uniform dye penetration.

[0069] Table 4. K / S values ​​of yarns after dyeing with different amounts of indigo ammonia reducing dyeing solution

[0070] 40 g / L indigo ammonia reducing solution (mL) 1 2 3 4 5 K / S value 6.8 13.5 13.4 13.0 12.4

[0071] Therefore, it can be seen that this application, by adopting the above technical solution, has the following significant technical effects:

[0072] 1. The reducing dye solution prepared with concentrated ammonia can be easily mixed with liquid ammonia in any proportion, making it easy to prepare reducing dye solutions with different water contents.

[0073] 2. The presence of water in the liquid ammonia reducing dyeing solution creates a strongly alkaline environment, which helps maintain the reduced state of the indigo vat dye during dyeing and prevents the indigo vat dye from being oxidized during the dyeing process, thus avoiding the problem of the fiber not being fully dyed.

[0074] 3. Liquid ammonia reducing dye solution can quickly penetrate into the fiber, enabling rapid dyeing and saving production time;

[0075] 4. Liquid ammonia containing a small amount of moisture still has the effect of mercerizing and decrystallizing the fiber. During the dyeing process of indigo liquid ammonia reduction dyeing solution, the amorphous area of ​​the fiber increases, which improves the dye uptake rate, that is, dyeing and mercerizing are completed simultaneously.

[0076] 5. The liquid ammonia reducing dye solution contains a small amount of water, which is beneficial to the stability and reproducibility of the dyeing effect;

[0077] 6. The entire dyeing process uses less water and less dye, and the indigo vat dye and liquid ammonia are easy to recycle.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for dyeing cellulose fibers, characterized in that, include: A strong alkali and sodium hydrosulfite are mixed in concentrated ammonia water to obtain a reducing solution; The vat dye is added to the reducing solution and reduced at 30-50°C for 10-60 minutes. Then, it is cooled to room temperature to obtain the vat dye solution. Liquid ammonia is added to the reducing dye solution to obtain a liquid ammonia reducing dye solution; the concentration of the reducing dye in the reducing dye solution is 30-60 g / L, the volume ratio of the reducing dye solution to the liquid ammonia is (1-5):(15-19), and the reducing dye includes indigo reducing dye. Cellulose fibers are immersed in the liquid ammonia reducing dye solution for dyeing, and then oxidized and soaped in the air to obtain dyed cellulose fibers.

2. The dyeing method for cellulose fibers according to claim 1, characterized in that, The ammonia content in the concentrated ammonia solution is 20-30%.

3. The dyeing method for cellulose fibers according to claim 1, characterized in that, The concentration of the strong alkali dissolved in the concentrated ammonia solution is 10-60 g / L; or / and The concentration of sodium hydrosulfite dissolved in the concentrated ammonia water is 80-200 g / L.

4. The dyeing method for cellulose fibers according to claim 1, characterized in that, The cellulose fibers include one or more of cotton fibers, linen fibers, viscose fibers, and modal fibers.

5. The dyeing method for cellulose fibers according to claim 4, characterized in that, The morphological structure of the cellulose fiber can be any one of loose fiber, yarn, or fabric.

6. The dyeing method for cellulose fibers according to claim 1, characterized in that, The dyeing includes either immersion dyeing or pad dyeing.

7. The dyeing method for cellulose fibers according to claim 1, characterized in that, The staining time is 1-10 minutes.

8. A cellulose fiber, characterized in that, It is prepared by the dyeing method of cellulose fibers according to any one of claims 1-7.

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