Printed cloth dye and dye manufacturing process thereof

Abstract

The invention relates to a printed cloth dye and a dye manufacturing process thereof, and belongs to the technical field of textile dyes. The printed cloth dye comprises the following main components: vegetable dye, soybean curb residue powder and vegetable gum. Lithospermum erythrorhizon is used as a raw material and is subjected to crushing, enzymolysis, membrane separation and purification and concentration to obtain the plant dye, and the quality of the plant dye is improved by adopting membrane separation and purification; the soybean curb residues are dried in the sun and then ground to obtain soybean curb residue powder which is rich in protein and can improve the color fastness of the fabric; active groups of the vegetable gum, the vegetable dye and the fibers are subjected to a cross-linking reaction, a film is formed on the surface of the fiber layer, and the pigment is fixed on the fiber layer. Therefore, the green, natural and easy-to-color printed cloth dye can be prepared according to the formula.

Description

Technical Field

[0001] The invention belongs to the technical field of textile dyes and relates to a printed cloth dye and a dye production process thereof. Background Art

[0002] Traditional dyes usually contain chemicals, which pose certain risks to the environment and human health. Therefore, in recent years, research and development of new environmentally friendly dyes have attracted attention. As a natural, environmentally friendly and sustainable dye, plant dyes are increasingly valued. Compared with traditional dyes, the production process of plant dyes is basically pollution-free and environmentally friendly. Plant dyes can have better affinity with fiber materials during the dyeing process, can produce rich color effects, and have a natural and unique aesthetic.

[0003] Plant dyes refer to pigments extracted from plants for dyeing. According to their sources and properties, plant dyes can be divided into: (1) Natural plant dyes, that is, natural pigments extracted from the roots, stems, leaves, flowers or fruits of plants. (2) Plant chlorophyll dyes, mainly pigments extracted from green leafy plants. (3) Plant lignin dyes, that is, pigments extracted from wood. (4) Plant resin dyes, that is, pigments extracted from plant resins. (5) Plant oxalic acid dyes, that is, oxalic acid substances extracted from plants. However, from the perspective of the printing and dyeing industry, the overall proportion of plant dyes is still relatively low. This is mainly because plant dyes are natural extracts and their product purity is not high. This has always been a practical problem in their industrial preparation and is also their biggest disadvantage compared to chemical dyes. In addition, plant dyes have low affinity, resulting in low color fastness. Summary of the invention

[0004] The present invention relates to a printed cloth dye and a dye production process thereof, and belongs to the technical field of textile dyes. The present invention discloses a printed cloth dye, the main components of which are: plant dye, bean curd residue powder, and plant gum; the present invention also discloses a dye production process, using lithospermum officinale as a raw material, crushing it, enzymolysis, membrane separation purification and concentration to obtain the plant dye, and the process adopts membrane separation purification to improve the quality of the dye; the bean curd residue is dried and then ground to obtain the bean curd residue powder, which is rich in protein and can improve the color fastness of the fabric; the active group of the plant gum undergoes a cross-linking reaction with the plant dye and the fiber, forms a film on the surface of the fiber layer, and fixes the pigment to the fiber layer. Therefore, the present invention can prepare a green, natural and easy-to-color printed cloth dye through the above formula.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A printed cloth dye, comprising the following raw materials in parts by weight: 80-85 parts of plant dye, 5-7 parts of bean curd dregs powder, and 10-15 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0007] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0008] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0009] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0010] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0011] Furthermore, in the step (1), the drying temperature and time are 40-46° C. and 30-60 min respectively, and the mesh size of the sieving is 40-80 mesh.

[0012] Furthermore, in the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 20-50 g:8-25 L.

[0013] Furthermore, in the step (2), the mass ratio of the powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 50-60° C. and 4.5-6.5, respectively.

[0014] Furthermore, in step (3), the volume ratio of the separation liquid to the solvent is 1-2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 30-50° C. and 20-40 min, respectively.

[0015] Furthermore, in step (4), the selective permeable membrane refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0016] Furthermore, the pressure and temperature of the reduced pressure concentration in step (4) are 1.33-1.5 Pa and 25-30° C., respectively.

[0017] Furthermore, the preparation method of the bean curd dregs powder is: drying the bean curd dregs, grinding and sieving to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 400-600 meshes.

[0018] Furthermore, the plant gum is at least one of tianqing gum, guar gum, sesame gum and fenugreek gum.

[0019] Furthermore, the printed cloth dye is obtained by mixing plant dye, bean curd dregs powder and plant gum.

[0020] The production process of the printed cloth dye comprises the step of mixing plant dye, bean curd dregs powder and plant glue.

[0021] Beneficial effects of the present invention:

[0022] In the process for preparing plant dyes of the present invention, microfiltration membrane and nanofiltration membrane are used for purification to improve the purity of the dyes, thereby improving the coloring effect of the dyes; bean curd dregs powder is added, which is rich in protein and can further improve the color fastness of the fabric; at the same time, the colloid active groups in the plant gum react with the plant dyes and fibers to form a film on the surface of the fiber layer, thereby fixing the pigment on the fiber layer. DETAILED DESCRIPTION

[0023] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with embodiments.

[0024] Example 1

[0025] A printed cloth dye, comprising the following raw materials in parts by weight: 80 parts of plant dye, 5 parts of bean curd dregs powder, and 10 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0026] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0027] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0028] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0029] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0030] The drying temperature and time in step (1) are 40° C. and 30 min respectively, and the mesh size of the sieving is 40 meshes.

[0031] In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 20 g:8 L.

[0032] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 50° C. and 4.5, respectively.

[0033] In the step (3), the volume ratio of the separation liquid to the solvent is 1:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 30° C. and 20 min, respectively.

[0034] The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0035] The pressure and temperature of reduced pressure concentration in step (4) are 1.33 Pa and 25° C. respectively.

[0036] The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 400 meshes.

[0037] The plant gum is Tianqing gum.

[0038] The printed cloth dye is prepared by mixing plant dye, bean curd dregs powder and plant gum.

[0039] The cellulase was purchased from Shengrun Company; xylanase: CAS No. 9025-57-4; the nanofiltration membrane was purchased from: nanofiltration membrane / Dow-NF90-2540; the Tianqing gum was purchased from: Tianqing gum / Yuhe.

[0040] Example 2

[0041] A printed cloth dye, comprising the following raw materials in parts by weight: 82 parts of plant dye, 6 parts of bean curd dregs powder, and 12.5 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0042] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0043] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0044] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0045] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0046] The drying temperature and time in step (1) are 43° C. and 45 min respectively, and the mesh size of the sieving is 60 meshes.

[0047] The solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water in step (2) is 35 g:15 L.

[0048] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 55° C. and 5.5, respectively.

[0049] In the step (3), the volume ratio of the separation liquid to the solvent is 1.5:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 40° C. and 30 min, respectively.

[0050] The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0051] The pressure and temperature of reduced pressure concentration in step (4) are 1.4 Pa and 28° C. respectively.

[0052] The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 500 meshes.

[0053] The plant gum consists of field gum and guar gum, wherein the mass ratio of field gum to guar gum is 1:1.

[0054] The printed cloth dye is prepared by mixing plant dye, bean curd dregs powder and plant gum.

[0055] The cellulase was purchased from Shengrun Company, xylanase: CAS No. 9025-57-4; the nanofiltration membrane was purchased from: nanofiltration membrane / Dow-NF90-2540; the Tianqing gum was purchased from: Tianqing gum / Yuhe; the guar gum was purchased from: guar gum / Xuelong brand.

[0056] Example 3

[0057] A printed cloth dye, comprising the following raw materials by weight: 85 parts of plant dye, 7 parts of bean curd dregs powder, and 15 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0058] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0059] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0060] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0061] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0062] The drying temperature and time in step (1) are 46° C. and 60 min respectively, and the mesh size of the sieving is 80 meshes.

[0063] In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 50 g:25 L.

[0064] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 60° C. and 6.5, respectively.

[0065] In the step (3), the volume ratio of the separation liquid to the solvent is 2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 50° C. and 40 min, respectively.

[0066] The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0067] The pressure and temperature of reduced pressure concentration in step (4) are 1.5 Pa and 30° C. respectively.

[0068] The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 600 meshes.

[0069] The plant gum consists of field gum, guar gum, sesame gum and fenugreek gum, wherein the mass ratio of field gum, guar gum, sesame gum and fenugreek gum is 1:1:1:1.

[0070] The printed cloth dye is prepared by mixing plant dye, bean curd dregs powder and plant gum.

[0071] The cellulase was purchased from Shengrun Company, xylanase: CAS No. 9025-57-4; the nanofiltration membrane was purchased from: nanofiltration membrane / Dow-NF90-2540; the Tianqing gum was purchased from: Tianqing gum / Yuhe; the guar gum was purchased from: guar gum / Xuelong brand; the sesame gum was purchased from: sesame gum / Best; the fenugreek gum was purchased from: fenugreek gum / Yikan.

[0072] Comparative Example 1

[0073] On the basis of Example 3, a printed cloth dye comprises the following raw materials in parts by weight: 85 parts of plant dye, 7 parts of bean curd dregs powder, and 15 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0074] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0075] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0076] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain an extract;

[0077] (4) The product is then concentrated under reduced pressure to obtain the plant dye.

[0078] The drying temperature and time in step (1) are 46° C. and 60 min respectively, and the mesh size of the sieving is 80 meshes.

[0079] In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 50 g:25 L.

[0080] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 60° C. and 6.5, respectively.

[0081] In the step (3), the volume ratio of the separation liquid to the solvent is 2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 50° C. and 40 min, respectively.

[0082] The pressure and temperature of reduced pressure concentration in step (4) are 1.5 Pa and 30° C. respectively.

[0083] The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 600 meshes.

[0084] The plant gum consists of field gum, guar gum, sesame gum and fenugreek gum, wherein the mass ratio of field gum, guar gum, sesame gum and fenugreek gum is 1:1:1:1.

[0085] The printed cloth dye is prepared by mixing plant dye, bean curd dregs powder and plant gum.

[0086] The cellulase was purchased from Shengrun Company, xylanase: CAS No. 9025-57-4; the purchase source of Tianqing gum: Tianqing gum / Yuhe; the purchase source of guar gum: guar gum / Xuelong brand-9000-30-0; the purchase source of sesame gum: sesame gum / Best; the purchase source of fenugreek gum: fenugreek gum / Yikang.

[0087] Comparative Example 2

[0088] On the basis of Example 3, a printed cloth dye comprises the following raw materials in parts by weight: 85 parts of plant dye and 23 parts of plant gum. The preparation method of the plant dye comprises the following steps:

[0089] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0090] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0091] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0092] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0093] The drying temperature and time in step (1) are 46° C. and 60 min respectively, and the mesh size of the sieving is 80 meshes.

[0094] In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 50 g:25 L.

[0095] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 60° C. and 6.5, respectively.

[0096] In the step (3), the volume ratio of the separation liquid to the solvent is 2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 50° C. and 40 min, respectively.

[0097] The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0098] The pressure and temperature of reduced pressure concentration in step (4) are 1.5 Pa and 30° C. respectively.

[0099] The plant gum consists of field gum, guar gum, sesame gum and fenugreek gum, wherein the mass ratio of field gum, guar gum, sesame gum and fenugreek gum is 1:1:1:1.

[0100] The printed cloth dye is prepared by mixing plant dye and plant gum.

[0101] The cellulase was purchased from Shengrun Company, xylanase: CAS No. 9025-57-4; the nanofiltration membrane was purchased from: nanofiltration membrane / Dow-NF90-2540; the Tianqing gum was purchased from: Tianqing gum / Yuhe; the guar gum was purchased from: guar gum / Xuelong brand; the sesame gum was purchased from: sesame gum / Best; the fenugreek gum was purchased from: fenugreek gum / Yikan.

[0102] Comparative Example 3

[0103] On the basis of Example 3, a printed cloth dye comprises the following raw materials in parts by weight: 85 parts of plant dye and 23 parts of tofu dregs powder. The preparation method of the plant dye comprises the following steps:

[0104] (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder;

[0105] (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting;

[0106] (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract;

[0107] (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

[0108] The drying temperature and time in step (1) are 46° C. and 60 min respectively, and the mesh size of the sieving is 80 meshes.

[0109] In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 50 g:25 L.

[0110] In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 60° C. and 6.5, respectively.

[0111] In the step (3), the volume ratio of the separation liquid to the solvent is 2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 50° C. and 40 min, respectively.

[0112] The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

[0113] The pressure and temperature of reduced pressure concentration in step (4) are 1.5 Pa and 30° C. respectively.

[0114] The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 600 meshes.

[0115] The printed cloth dye is prepared by mixing plant dye and bean curd dregs powder.

[0116] The cellulase was purchased from Shengrun Company, xylanase: CAS No. 9025-57-4; the nanofiltration membrane was purchased from: nanofiltration membrane / Dow-NF90-2540.

[0117] 1. Performance Testing

[0118] The printed cloth dye components prepared in Examples 1-3 and Comparative Examples 1-3 were mixed with water to form printing paste as samples, and the amount of water added accounted for 90% of the mass of the paste. The printing process was as follows: fiber cloth was immersed in the paste → pre-baked (80°C, 10 min) → steamed (100°C, 20 min) → cold water washed → soap washed (neutral soaping agent 0.5 g / L, bath ratio 1:50, temperature 40°C, time 8 min) → hot water washed → cold water washed → drying (80°C, 10 min).

[0119] Then the clarity of the fabric is judged by observation. The color fastness to rubbing is tested with reference to GB / T3920-2008 "Textiles - Color Fastness - Tests for Color Fastness to Rubbing", and the staining of the wet rubbing cloth is evaluated with a gray sample card. The color fastness to washing is tested on a washing color fastness tester with reference to GB / T3921-2008 "Textiles - Color Fastness - Tests for Color Fastness to Washing".

[0120] The above test results are shown in Table 1.

[0121] Table 1 Test results

[0122]

[0123]

[0124] It can be seen from Table 1 that the outlines of Examples 1-3 and Comparative Examples 2-3 are very clear, while Comparative Example 1 is only relatively clear. The color fastness to rubbing and the color fastness to soaping of Examples 1-3 are both level 5, while the comparative examples are all less than level 5. In Comparative Example 1, the preparation process of the plant dye is not subjected to membrane separation and purification, and the purity of the plant dye is reduced, thereby affecting the coloring effect and color fastness; in Comparative Examples 2-3, the bean curd dregs powder is removed and replaced with plant gum or the plant gum is removed and replaced with bean curd dregs powder. The color fastness is reduced when either one is removed, so the two work together to improve the color fastness effect.

[0125] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A printed cloth dye, characterized in that: The printed cloth dye comprises the following raw materials in parts by weight: 80-85 parts of plant dye, 5-7 parts of bean curd dregs powder, and 10-15 parts of plant gum. The preparation method of the plant dye comprises the following steps: (1) Using lithospermum officinale stems as raw materials, washing, drying, crushing, and sieving to form powder; (2) taking powder, cellulase and xylanase, adding distilled water, stirring and mixing, and heating and fermenting; (3) then filtering and separating, adding a solvent to the obtained separated liquid, then heating, and vacuum filtering to obtain a crude extract; (4) The crude extract is passed through a selectively permeable membrane and pressure is applied to obtain an extract, which is then concentrated under reduced pressure to obtain the plant dye.

2. A printed cloth dye according to claim 1, characterized in that: The drying temperature and time in step (1) are 40-46° C. and 30-60 min, respectively, and the mesh size of the sieving is 40-80 meshes.

3. A printed cloth dye according to claim 1, characterized in that: In the step (2), the solid-liquid ratio of the total mass of the powder, cellulase and xylanase to distilled water is 20-50 g:8-25 L.

4. A printed cloth dye according to claim 1, characterized in that: In the step (2), the mass ratio of powder, cellulase and xylanase is 10:0.5:0.5, and the temperature and pH value of the elevated temperature fermentation are 50-60° C. and 4.5-6.5, respectively.

5. A printed cloth dye according to claim 1, characterized in that: In the step (3), the volume ratio of the separation liquid to the solvent is 1-2:2, wherein the solvent is glacial acetic acid, and the heating temperature and time are 30-50° C. and 20-40 min, respectively.

6. A printed cloth dye according to claim 1, characterized in that: The selective permeable membrane in step (4) refers to first passing through a microfiltration membrane and then passing through a nanofiltration membrane, wherein the pore size of the microfiltration membrane is 0.22 μm, the pressure passing through the microfiltration membrane is 0.075 MPa, and the pressure passing through the nanofiltration membrane is 0.3 MPa.

7. A printed cloth dye according to claim 1, characterized in that: The pressure and temperature of the reduced pressure concentration in step (4) are 1.33-1.5 Pa and 25-30° C. respectively; The preparation method of the bean curd dregs powder comprises: drying the bean curd dregs in the sun, grinding the bean curd dregs and sieving them to obtain the bean curd dregs powder, wherein the mesh number of the sieving is 400-600 meshes.

8. A printed cloth dye according to claim 1, characterized in that: The plant gum is at least one of tianqing gum, guar gum, sesame gum and fenugreek gum.

9. A printed cloth dye according to claim 1, characterized in that: The printed cloth dye is obtained by mixing plant dye, bean curd dregs powder and plant gum.

10. A process for producing a printed cloth dye according to any one of claims 1 to 9, characterized in that: The method comprises the steps of mixing vegetable dye, bean curd dregs powder and vegetable gum.

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