A natural pigment composition and preparation method thereof

Abstract

The present invention discloses a natural pigment composition and a preparation method thereof, belonging to the field of pigment technology. The natural pigment composition, its raw materials include a first pigment, a second pigment, a complexing agent and / or a coating skeleton material, the first pigment is tea pigment, and the second pigment is one or more of curcumin, sunflower yellow, and safflower yellow. The present invention also provides a preparation method of the natural pigment composition, comprising the following steps: dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution; adding the complexing agent to the first mixed solution to carry out a complex reaction to obtain a second solution; adding the coating skeleton material to the second solution and shaking the reaction at 25-30°C for 10-12h to obtain a third solution; and freeze-drying the third solution to obtain the natural pigment composition. The natural pigment composition in the present invention has good coloring and good color fixation.

Description

Technical Field

[0001] The present invention relates to the technical field of pigments, and in particular to a natural pigment composition and a preparation method thereof. Background Art

[0002] Cellulose fibers include natural cellulose fibers and regenerated cellulose fibers. Natural cellulose fibers are directly obtained from plant tissues without chemical treatment. The raw materials are generally spun and manufactured mechanically to form fabrics. Common types include cotton and linen, with newer natural cellulose fibers emerging, such as bamboo and kapok fibers. Regenerated cellulose fibers are made from natural cellulose. During the manufacturing process, the cellulose is converted into a soluble cellulose derivative, which is then extruded through a spinneret and placed into a chemical bath where it hardens into fibers. This method is also known as wet spinning.

[0003] Natural plant dyes are environmentally friendly and harmless to humans. Dyeing cellulose fabrics with natural dyes not only adds significant value to the product but also meets the demand for all-natural clothing materials. However, the molecular structure of most natural dyes contains groups such as carboxyl and hydroxyl groups, making the pigments highly water-soluble. However, the fiber surface lacks groups that can stably bind to the dye. As a result, the pigments tend to accumulate on the fiber surface, mostly bound by van der Waals forces and hydrogen bonds. Their ability to diffuse into the fiber is limited, resulting in low dye uptake and poor color fastness.

[0004] Natural pigments are commonly used in the field of dyeing cotton and linen textiles. Their natural coloring and rich colors are deeply loved by people. In the existing technology, when cotton, linen and other textiles are dyed with natural pigments, technical problems such as coloring difficulty and poor color fastness will occur. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide a natural pigment composition and a preparation method thereof, and solve the technical problems in the prior art such as difficulty in coloring and poor color fastness of natural pigments during dyeing.

[0006] To achieve the above technical objectives, the present invention provides a natural pigment composition comprising a first pigment, a second pigment, a complexing agent, and / or a coating skeleton material, wherein the first pigment is a tea pigment, and the second pigment is one or more of curcumin, sunflower yellow, and safflower yellow. The tea pigment in the present invention may be a tea pigment extracted from tea leaves such as green tea and black tea via alcohol extraction.

[0007] Preferably, the complexing agent is lanthanum chloride and ferric chloride, and the mass ratio of the two is 1:0.6-1.1, specifically 1:0.8, 1:1, etc., and the coating framework material is a metal organic framework material.

[0008] Preferably, the coating framework material is a zeolite imidazolate framework material.

[0009] Preferably, the pore size of the zeolite imidazolate framework material is 3-5 nm.

[0010] Preferably, the raw materials include 1-1.5 parts of the first pigment, 1.5-2.5 parts of the second pigment, 4-6 parts of the complexing agent, and 1.5-2 parts of the coating skeleton material in parts by mass.

[0011] A method for preparing the natural pigment composition described above comprises the following steps:

[0012] S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution;

[0013] S2, adding a complexing agent to the first mixed solution to carry out a complexing reaction to obtain a second solution;

[0014] S3, adding the coated skeleton material to the second solution and reacting at 25-30° C. for 10-12 hours to obtain a third solution;

[0015] S4. Freeze-drying the third solution to obtain the natural pigment composition.

[0016] Preferably, the solute concentration of the first mixed solution in S1 is 2.5-4 g / L.

[0017] Preferably, the reaction temperature of the complexation reaction in S2 is 60-70°C.

[0018] An application of the above-mentioned natural pigment composition in textile dyeing comprises the following steps:

[0019] (1) mixing β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water, and reacting to obtain a modified solution;

[0020] (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a solution bath ratio of 1:50-60, and drying to obtain the modified fabric;

[0021] (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 15-18 g / L;

[0022] (4) placing the modified fabric into the dyeing solution, dyeing the fabric according to a solution bath ratio of 1:40-50, and drying to obtain the dyed fabric.

[0023] Preferably, the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 70-90 g / L, 40-60 g / L, 20-40 g / L and 50-70 g / L, respectively.

[0024] Preferably, the drying temperature is 70-80°C.

[0025] The lanthanum chloride in the natural pigment composition of the present invention forms a complex with the phenolic hydroxyl groups in the first and second pigments (tea pigment, curcumin, sunflower yellow, and safflower yellow all contain phenolic hydroxyl groups). The rare earth ion, as the central ion, has a strong complexation with the ligand containing a lone pair electron group. In the amorphous region of the fiber, it acts as a crosslinking agent through coordination bonds and covalent bonds, shifting the absorption peak of the dye molecule to a longer wavelength, resulting in a change and deepening of the color, and can improve the K / S value of the dyed silk fabric. In addition, the natural pigment composition can be applied to the textile dyeing process to La 3+ It chelates with phenolic hydroxyl groups and amino and carboxyl groups on the fiber surface to improve the coloring properties of the pigment.

[0026] Ferric chloride (FeCl3) releases trivalent Fe ions to form strong coordination bonds with multi-electron donor functional groups such as hydroxyl and carboxyl groups in the pigment molecules, achieving complexation. This process significantly improves the stability of the pigment in various environments and enhances the color fastness of the pigment dyeing process, making the color more durable and less susceptible to washing and friction.

[0027] At the same time, La 3+ and Fe 3+ As a complexation substance, La 3+ and Fe 3+ In the complexation, different coordination numbers and coordination geometries are exhibited, and this complementary effect can further enhance the structural stability and performance of the complex. 3+ Usually form octahedral or tetragonal coordination, while Fe 3+ Different coordination structures can cover more types of pigment functional groups, enhance the overall complexing ability and improve the color fastness of the pigment.

[0028] At the same time, the present invention uses zeolite imidazolate framework materials as coating materials for pigments modified with lanthanum chloride and ferric chloride. Zeolite imidazolate framework materials have a high surface area and a highly ordered pore structure, which can effectively coat and protect natural pigment molecules. This coating can provide a physical barrier to prevent the pigment molecules from being affected by environmental factors such as light, heat, and oxygen, thereby improving the stability and durability of the pigment. At the same time, this coating will not affect the color release behavior of the pigment; this type of material has good surface chemical properties and dispersibility, and can effectively and evenly disperse the pigment molecules. In applications such as textile dyeing, good dispersibility can ensure uniform dyeing and avoid color spots and color difference problems. The coating of zeolite imidazolate framework materials can significantly improve the color fastness of the pigment and prevent the dyed textiles from fading under conditions such as washing, friction, and light. This not only improves the aesthetics of the textiles, but also extends their service life.

[0029] Pigment molecules in natural pigments (such as tea pigments, curcumin, etc.) usually contain multiple active groups such as hydroxyl, carboxyl, and phenolic hydroxyl groups, which can react with lanthanum ions or Fe 3+ The coordination bonds form complexes. Due to the presence of coordination bonds, the stability of the complexes formed is significantly improved, and they can resist the erosion of external environmental factors (such as light, heat, and oxidants).

[0030] After the complexation reaction is complete, the pigment is coated with a zeolite imidazolate framework material. This material possesses a highly ordered nanopore structure, which allows for precise and selective adsorption of the complexed pigment molecules. The complexation reaction alters the size and surface charge of the pigment molecules, increasing their adsorption advantage within specific pores. The coated pigment molecules are confined within the nanopores of the zeolite imidazolate framework, forming a physical barrier that reduces direct contact with the external environment, thereby enhancing their resistance to light and oxidation, and improving color fastness.

[0031] The formation of the complex enhances the stability and coloring properties of the pigment molecules, while the coating provides an additional physical barrier, reducing the loss and decomposition of the pigment molecules during use, thereby significantly improving the dyeing fastness.

[0032] When the natural pigment composition of the present invention is applied to cotton, linen and other fabrics, β-cyclodextrin and chitosan can be added to the fabric to be dyed for modification and finishing.

[0033] β-cyclodextrin has certain similarities with the cellulose molecules of textiles. They have the same structural unit glucose, connecting bond α-1.4 glycosidic bond and active functional group hydroxyl group. At the same time, the fabric modified with β-cyclodextrin has an inclusion effect on curcumin, sunflower yellow and safflower yellow. Here, β-cyclodextrin is equivalent to playing a bridging role. The surface of the textile is first grafted with β-cyclodextrin, and then dyed. The β-cyclodextrin group will adsorb the pigment molecules through inclusion, thereby enhancing the coloring of the pigment.

[0034] During dyeing, the tea polyphenols in the tea pigment bind to the chitosan on the fabric through ionic bonds. This bond energy is stronger than van der Waals forces, which can improve the dye uptake rate. The electrostatic attraction between the dye anions and the protonated amino groups of chitosan also increases the dye uptake rate. Furthermore, chitosan penetrates the fiber and, when the pigment binds, it also allows the pigment to enter the fiber, further preventing the pigment from swelling, dissolving, and shedding during fastness testing and wearing, thereby improving the pigment's friction fastness.

[0035] β-cyclodextrin, through its hydrophilic outer wall and hydrophobic inner cavity, effectively encapsulates natural pigment molecules, improving their solubility and dispersibility. The amino groups in chitosan can form coordination bonds with the carboxyl or phenolic hydroxyl groups on the dye molecules, strengthening the binding force between the pigment and the fiber. β-cyclodextrin provides an inclusion space to protect the natural pigment, shielding it from direct environmental influences (such as light and oxidants). Chitosan, on the other hand, forms a protective layer on the fiber surface, further enhancing the pigment's adhesion and stability. The combined effect of these two further improves the pigment's colorability and durability.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The lanthanum chloride and ferric chloride in the natural pigment composition of the present invention are complexed with the phenolic hydroxyl groups and carboxyl groups in the first pigment and the second pigment, and chelated with the amino and carboxyl groups on the fiber surface, thereby improving the coloring properties of the pigments;

[0038] 2. After complexation, the pigment molecules are confined in the nanopores of the zeolite imidazolate framework material through coating, forming a physical barrier, reducing the direct contact between the pigment molecules and the external environment, thereby enhancing the pigment's light resistance and antioxidant ability, and improving color fixation;

[0039] 3. During the application process, the pigment composition of the present invention is first modified and finished on the textile to be treated. β-cyclodextrin and chitosan are first grafted onto the textile to be dyed. During the dyeing process, the dye anions and the protonated amino groups of chitosan are attracted by electrostatic attraction. At the same time, the pigment molecules also undergo inclusion reaction with β-cyclodextrin, thereby achieving rapid coloring of the pigment.

[0040] 4. The pigment in the present invention is pre-treated by complexation followed by coating to improve the coloring and color fixation properties of the pigment. During the dyeing process, the active substances on the pigment molecules can be quickly and tightly combined with the finished textile. The preparation method of the present invention is simple, green and pollution-free. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] The preparation method of the zeolite imidazolate framework material of the present invention comprises the following steps: dissolving 0.5-2.5 parts of zinc nitrate and 2-4 parts of dimethylimidazole in anhydrous methanol, respectively, by weight, mixing and stirring to obtain a suspension liquid; then centrifuging to obtain a precipitate; washing with methanol, drying, and grinding the washed precipitate to obtain the zeolite imidazolate framework material.

[0043] The raw materials used in the following examples were obtained as follows:

[0044] The method for obtaining green tea pigment is as follows: drying green tea leaves at 50°C to constant weight, and then crushing the leaves into powder with a particle size of less than 100 microns; adding the tea powder to 75wt% ethanol, with the mass ratio of the two being 1:10; extracting the solution at 70°C for 2h, filtering and obtaining an alcohol extraction solution; and volatilizing the ethanol solvent at 45°C until the solvent is completely evaporated to obtain the tea pigment.

[0045] Theabrownin is alcohol-extracted theabrownin with a purity of 40% and sold by Shaanxi Ronglin Biotechnology Co., Ltd.

[0046] The zeolite imidazolate framework material was prepared in the laboratory. The preparation process involved dissolving 1.5 parts zinc nitrate and 3.32 parts dimethylimidazole, respectively, in 70 parts anhydrous methanol, mixing the two and stirring at 200 rpm for 24 hours at atmospheric pressure and 25°C to obtain a milky white suspension. The suspension was then poured into a centrifuge tube and centrifuged at 8500 rpm / min for 5 minutes to obtain a milky white crystalline precipitate. The precipitate was then washed with methanol. This step was repeated three times to obtain a washed milky white crystalline precipitate, which was then dried in a vacuum drying oven at 70°C for 24 hours. The dried reaction mixture was removed and thoroughly ground in a mortar to obtain the final product. The preparation of the zeolite imidazolate framework material can be adjusted according to the dosage.

[0047] Example 1

[0048] This embodiment provides a natural pigment composition, the raw materials of which include, by mass, 1 part of a first pigment, 1.5 parts of a second pigment, 2 parts of lanthanum chloride, 2 parts of ferric chloride, and 1.5 parts of a zeolite imidazolate framework material, wherein the pore diameter of the zeolite imidazolate framework material is 3 nm, the first pigment is a green tea pigment, and the second pigment is curcumin.

[0049] A method for preparing the natural pigment composition described above comprises the following steps:

[0050] S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution with a solute concentration of 2.5 g / L;

[0051] S2, adding lanthanum chloride and ferric chloride as complexing agents to the first mixed solution for complexation reaction at 60° C. for 40 min to obtain a second solution;

[0052] S3, adding the coated framework material zeolite imidazolate framework material to the second solution and shaking the mixture at 25° C. for 10 hours to obtain a third solution;

[0053] S4. Freeze-drying the third solution at -10°C to a water content of 2% to obtain the natural pigment composition.

[0054] An application of the natural pigment composition as described above in textile dyeing comprises the following steps:

[0055] (1) β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water are mixed and reacted to obtain a modified solution, wherein the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 80 g / L, 50 g / L, 30 g / L and 60 g / L, respectively;

[0056] (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a solution bath ratio of 1:50, soaking for 1 hour, at a temperature of 80°C, and drying at 120°C for 10 minutes to obtain the modified fabric;

[0057] (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 15 g / L;

[0058] (4) The modified fabric is placed in the dyeing solution, and dyed according to a solution bath ratio of 1:40, the dyeing temperature is 80° C., the dyeing time is 50 min, and the dyed fabric is obtained after drying at 70° C. for 4 h.

[0059] Example 2

[0060] This embodiment provides a natural pigment composition, the raw materials of which include, by mass, 1.5 parts of a first pigment, 2.5 parts of a second pigment, 3 parts of lanthanum chloride, 3 parts of ferric chloride, and 2 parts of a zeolite imidazolate framework material, wherein the pore diameter of the zeolite imidazolate framework material is 5 nm, the first pigment is theabrownin, and the second pigment is sunflower yellow pigment.

[0061] A method for preparing the natural pigment composition described above comprises the following steps:

[0062] S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution with a solute concentration of 4 g / L;

[0063] S2, adding lanthanum chloride and ferric chloride as complexing agents to the first mixed solution for complexation reaction at 70° C. for 40 min to obtain a second solution;

[0064] S3, adding the coated skeleton material to the second solution and shaking at 30° C. for 12 hours to obtain a third solution;

[0065] S4. Freeze-drying the third solution at -10°C to a water content of 2% to obtain the natural pigment composition.

[0066] An application of the natural pigment composition as described above in textile dyeing comprises the following steps:

[0067] (1) β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water are mixed and reacted to obtain a modified solution, wherein the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 80 g / L, 50 g / L, 30 g / L and 60 g / L, respectively;

[0068] (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a solution bath ratio of 1:60, soaking for 1 hour, at a temperature of 80°C, and drying at 130°C for 10 minutes to obtain the modified fabric;

[0069] (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 18 g / L;

[0070] (4) The modified fabric is placed in the dyeing solution, and the fabric is dyed according to a solution bath ratio of 1:50, the dyeing temperature is 80° C., the dyeing time is 50 min, and the dyed fabric is obtained after drying at 80° C. for 3 h.

[0071] Example 3

[0072] This embodiment provides a natural pigment composition, the raw materials of which include, by mass, 1.2 parts of a first pigment, 2 parts of a second pigment, 2.5 parts of lanthanum chloride, 2.5 parts of ferric chloride, and 1.8 parts of a zeolite imidazolate framework material, wherein the pore diameter of the zeolite imidazolate framework material is 4 nm, the first pigment is a green tea pigment, and the second pigment is a safflower yellow pigment.

[0073] A method for preparing the natural pigment composition described above comprises the following steps:

[0074] S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution with a solute concentration of 3 g / L;

[0075] S2, adding lanthanum chloride and ferric chloride as complexing agents to the first mixed solution for complexation reaction at 65° C. for 40 min to obtain a second solution;

[0076] S3, adding the coated skeleton material to the second solution and shaking the mixture at 28° C. for 11 hours to obtain a third solution;

[0077] S4. Freeze-drying the third solution at -10°C to a water content of 2% to obtain the natural pigment composition.

[0078] An application of the natural pigment composition as described above in textile dyeing comprises the following steps:

[0079] (1) β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water are mixed and reacted to obtain a modified solution, wherein the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 80 g / L, 50 g / L, 30 g / L and 60 g / L, respectively;

[0080] (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a bath ratio of 1:55, soaking for 1 hour, at a temperature of 80°C, and drying at 125°C for 10 minutes to obtain the modified fabric;

[0081] (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 16 g / L;

[0082] (4) The modified fabric is placed in the dyeing solution, and the fabric is dyed according to a solution bath ratio of 1:45, the dyeing temperature is 80°C, the dyeing time is 50 minutes, and the dyed fabric is obtained after drying at 75°C for 3.5 hours.

[0083] Example 4

[0084] This embodiment provides a natural pigment composition, the raw materials of which include, by mass, 1.5 parts of a first pigment, 2.5 parts of a second pigment, 2 parts of lanthanum chloride, 2 parts of ferric chloride, and 1.7 parts of a zeolite imidazolate framework material, wherein the pore diameter of the zeolite imidazolate framework material is 5 nm, the first pigment is a green tea pigment, and the second pigment is curcumin.

[0085] A method for preparing the natural pigment composition described above comprises the following steps:

[0086] S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution with a solute concentration of 4 g / L;

[0087] S2, adding lanthanum chloride and ferric chloride as complexing agents to the first mixed solution for complexation reaction at 60° C. for 40 min to obtain a second solution;

[0088] S3, adding the coated skeleton material to the second solution and shaking the mixture at 25° C. for 12 hours to obtain a third solution;

[0089] S4. Freeze-drying the third solution at -10°C to a water content of 2% to obtain the natural pigment composition.

[0090] An application of the natural pigment composition as described above in textile dyeing comprises the following steps:

[0091] (1) β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water are mixed and reacted to obtain a modified solution, wherein the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 80 g / L, 50 g / L, 30 g / L and 60 g / L, respectively;

[0092] (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a solution bath ratio of 1:50, soaking for 1 hour, at a temperature of 80°C, and drying at 120°C for 10 minutes to obtain the modified fabric;

[0093] (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 15 g / L;

[0094] (4) The modified fabric is placed in the dyeing solution, and the fabric is dyed according to a solution bath ratio of 1:40, the dyeing temperature is 80° C., the dyeing time is 50 min, and the dyed fabric is obtained after drying at 80° C. for 3 h.

[0095] Comparative Example 1

[0096] This comparative example is similar to Example 1, except that in this comparative example, an equal amount of β-cyclodextrin is replaced by chitosan during the application of the natural pigment composition in textile dyeing.

[0097] Comparative Example 2

[0098] This comparative example is similar to Example 1, except that in this comparative example, an equal amount of chitosan is replaced by β-cyclodextrin during the application of the natural pigment composition in textile dyeing.

[0099] Comparative Example 3

[0100] This comparative example is similar to Example 1, except that no zeolite imidazolate framework material is added to the natural pigment composition in this comparative example, and step S3 is not included in the preparation method of the natural pigment composition.

[0101] Comparative Example 4

[0102] This comparative example is similar to Example 1, except that in this comparative example, an equal amount of lanthanum chloride is replaced by ferric chloride in the natural pigment composition, and the ferric chloride is 4 parts.

[0103] Comparative Example 5

[0104] This comparative example is similar to Example 1, except that in this comparative example, an equal amount of ferric chloride is replaced by 4 parts of lanthanum chloride in the natural pigment composition.

[0105] The natural pigment compositions in Examples 1-4 and Comparative Examples 1-5 were tested for their coloring and color fastness during their application. The relevant test results are shown in Table 1. The K / S value of each fabric was measured using a Datacolor-600 spectrophotometer at 8 points evenly spaced on the fabric; the color fastness to rubbing was measured in accordance with GB / T3920-2008 "Textiles - Tests for Color Fastness - Rubbing Fastness"; the color fastness to washing was measured in accordance with GB / T3921-2008 "Textiles - Tests for Color Fastness - Color Fastness to Washing: Test 1"; and the color fastness to sunlight was measured in accordance with GB / T8427-2008 "Textiles - Tests for Color Fastness - Color Fastness to Artificial Light: Xenon Arc Light".

[0106] Table 1 Test results of coloring and color fixation properties of natural pigment compositions

[0107]

[0108]

[0109] The data in the table above show that the addition of β-cyclodextrin and chitosan has a significant effect on the coloring and color fixation of the pigment; the zeolite imidazolate framework material has a significant effect on improving the color fixation of the pigment; and the addition of lanthanum chloride and ferric chloride has a better effect on the coloring of the pigment.

[0110] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A natural pigment composition for cotton and linen textiles, characterized in that: The raw materials include a first pigment, a second pigment, a complexing agent and a coating skeleton material. The raw materials include 1-1.5 parts of the first pigment, 1.5-2.5 parts of the second pigment, 4-6 parts of the complexing agent and 1.5-2 parts of the coating skeleton material in parts by mass. The first pigment is green tea pigment or theabrownin, the second pigment is one or more of curcumin, sunflower yellow, and safflower yellow, the complexing agent is lanthanum chloride and ferric chloride, and the mass ratio of lanthanum chloride to ferric chloride is 1:0.6-1.1; The coating skeleton material is a metal organic framework material, the metal organic framework material is a zeolite imidazolate skeleton material, and the pore diameter of the zeolite imidazolate skeleton material is 3-5 nm. The preparation method of the zeolite imidazolate skeleton material comprises dissolving 0.5-2.5 parts of zinc nitrate and 2-4 parts of dimethylimidazole in anhydrous methanol, respectively, by weight, and then mixing and stirring to obtain a suspension liquid; Then centrifuge to obtain a precipitate; washing with methanol, drying the washed precipitate, and grinding to obtain the zeolite imidazolate framework material; The preparation method of the natural pigment composition comprises the following steps: S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution; S2, adding a complexing agent to the first mixed solution to carry out a complexing reaction to obtain a second solution; S3, adding the coated skeleton material to the second solution and reacting at 25-30° C. for 10-12 hours to obtain a third solution; S4. Freeze-drying the third solution to obtain the natural pigment composition.

2. A method for preparing the natural pigment composition according to claim 1, characterized in that: The following steps are involved: S1, dissolving the first pigment and the second pigment in deionized water to obtain a first mixed solution; S2, adding a complexing agent to the first mixed solution to carry out a complexing reaction to obtain a second solution; S3, adding the coated skeleton material to the second solution and reacting at 25-30° C. for 10-12 hours to obtain a third solution; S4. Freeze-drying the third solution to obtain the natural pigment composition.

3. The method according to claim 2, characterized in that The solute concentration of the first mixed solution in S1 is 2.5-4 g / L.

4. The method according to claim 2, characterized in that The reaction temperature of the complexation reaction in S2 is 60-70°C.

5. Use of the natural pigment composition according to claim 1 in textile dyeing, characterized in that: The following steps are involved: (1) mixing β-cyclodextrin, chitosan, sodium hypophosphite, citric acid and water, and reacting to obtain a modified solution, wherein the concentrations of β-cyclodextrin, chitosan, sodium hypophosphite and citric acid in the modified solution are 70-90 g / L, 40-60 g / L, 20-40 g / L and 50-70 g / L, respectively; (2) placing the fabric to be dyed into the modified solution, modifying the fabric according to a solution bath ratio of 1:50-60, and drying to obtain the modified fabric; (3) dissolving the natural pigment composition in deionized water to prepare a dyeing solution with a solute concentration of 15-18 g / L; (4) The modified fabric is placed in the dyeing solution and dyed according to a solution bath ratio of 1:40-50. The dyeing temperature of the fabric is 80-85° C. and the dyeing time is 40-50 min. The dyed fabric is obtained after drying.

6. The use according to claim 5, characterized in that The drying temperature is 70-80°C.

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