Method for improving color fastness of vegetable dye and color fixing agent

Abstract

The invention relates to the field of painting and calligraphy paper, and discloses a method for improving the color fastness of a vegetable dye and a color fixing agent. The color fixing agent used in the invention is a nano metal oxide which comprises at least one of nano zinc oxide, nano silicon dioxide and nano titanium dioxide. The vegetable dye comprises at least one of coptis chinensis, sappan wood and cape jasmine. Compared with the traditional color fixing agent, the color difference is reduced to 3.1 from 6.4 and the color fastness is improved to level 3 from level 2 after the coptis dyed calligraphy and painting paper fixed by the nano zinc oxide is subjected to ultraviolet radiation treatment, and the reduction amplitude reaches 51.56%. After the cape jasmine dyed calligraphy and painting paper subjected to color fixation by the nano zinc oxide is subjected to dry heat aging, the color difference is reduced from 5.90 to 1.41, the color fastness is improved from grade 3 to grade 5, and the reduction amplitude is 76.10%. After the cape jasmine dyed calligraphy and painting paper subjected to color fixation by using the nano silicon dioxide is subjected to visible light irradiation treatment, the color difference is reduced from 2.88 to 1.46, the color fastness is improved from grade 4 to grade 5, and the reduction amplitude is 49.31%.

Description

Technical Field

[0001] The present invention relates to the field of calligraphy and painting paper, and more specifically, to a method for improving the color fastness of plant dyes and a fixing agent. Background Art

[0002] Calligraphy and painting paper is the main carrier of China's long cultural history and a microcosm of Chinese civilization. Calligraphy and painting paper (pure bark Xuan paper) has extraordinary properties and has shown great prowess in the field of Chinese culture. It has a wide range of applications in writing, painting, rubbing, printing, mounting famous works, woodblock watermarking, etc. In addition, it can also be used to make (Xuan paper) albums, fan faces, and letter paper. Dyeing is an important processing step for colored calligraphy and painting paper. Dyes extracted from natural plants (such as gardenia, coptis, sappanwood, etc.) have bright colors and are therefore often used for dyeing calligraphy and painting paper. The color display principle of natural dyes is mainly that their molecular structures have unsaturated bonds such as aromatic rings, C=C double bonds, and carbonyl groups, and form a relatively large conjugated structure. This structure is easily damaged by external factors such as light, heat, and oxidation, resulting in fading. To address the problem of low color fastness of natural plant dyes, traditional colored calligraphy and painting paper uses materials such as soy milk, gelatin, and alum for protection. However, the effect of these substances on improving the light stability of plant dyes is not ideal. Therefore, it is of great significance to develop a method that can efficiently improve the color fastness of natural plant dyes used in calligraphy and painting paper.

[0003] Nano metal oxides are a type of light shielding agent with stable properties, having significant advantages such as non-toxicity, odorlessness, and long-lasting effects. They also have a strong shielding function for visible light and can shield both UVA and UVB. The functional mechanism of such substances as light shielding agents is mainly the reflection, refraction, and scattering of visible light, especially the reflection of ultraviolet light. At the same time, such substances also have a certain antibacterial effect. The excellent light shielding function and antibacterial properties of nano metal oxide materials have led to their widespread application in anti-ultraviolet coatings, air purification, antibacterial deodorization, plastics, rubbers, fabrics, and other fields. In the protection of paper cultural relics, nano titanium dioxide is mainly studied as an antibacterial agent, such as antibacterial research by blending with chitosan. In terms of the anti-ultraviolet property of paper, nano titanium dioxide is mostly used to make functional paper. In terms of improving the color fastness of colored calligraphy and painting paper, nano metal oxides such as zinc oxide, silicon dioxide, and titanium dioxide have great application potential and can solve the problem of the unsatisfactory color fixing effect of traditional fixing agent soy milk water, effectively protecting the color of colored calligraphy and painting paper.

[0004] The prior art "Research on the Development of Fixatives and Antibacterial Agents for Paper Cultural Relics and the Screening of Environmentally Friendly Antibacterial Agents" studied the protective effect of environmentally friendly anti-ultraviolet aging materials based on nano-titanium dioxide on paper cultural relics. The experimental results showed that 0.5% hydroxyethyl cellulose could effectively disperse and stabilize nano-titanium dioxide, and when the concentration of nano-titanium dioxide did not exceed 0.05%, the influence on the cyan color difference was not significant. This prior art focused on the strength retention, anti-ultraviolet ability, and antibacterial properties of paper, but failed to effectively improve the fading phenomenon of dyeing materials, and did not involve the specific improvement of the color fastness of plant dyes, thus unable to achieve significant effects in enhancing the color fastness of plant dyes. Summary of the Invention

[0005] In order to overcome the defect in the above prior art that it is impossible to achieve significant effects in enhancing the color fastness of plant dyes, the present invention provides a method for improving the color fastness of plant dyes.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A method for improving the color fastness of plant dyes, wherein the fixative used includes at least one of nano-metal oxides and nano-silica.

[0008] Further, the nano-metal oxide includes at least one of nano-zinc oxide and nano-titanium dioxide.

[0009] Preferably, the nano-zinc oxide has a hexagonal wurtzite structure, the nano-silica has a three-dimensional structure, and the nano-titanium dioxide has a rutile type.

[0010] Further, the particle size of the nano-metal oxide is 10 - 200 nm.

[0011] Further, the plant dyes include Coptis chinensis, Sappanwood, and Gardenia jasminoides.

[0012] Further, the color fastness of plant dyes on calligraphy and painting paper is improved.

[0013] Preferably, the calligraphy and painting paper is pure bark raw Xuan paper.

[0014] Further, the calligraphy and painting paper dyed with plant dyes is dyed by the following method:

[0015] S1. The plant materials used as dyes are crushed and screened, then steamed in water, and the dye solution is obtained after filtration;

[0016] S2. The calligraphy and painting paper is dyed with the dye solution.

[0017] Preferably, the plant materials are crushed and screened to 20 - 80 meshes.

[0018] Preferably, the calligraphy and painting paper is dyed by the dragging method.

[0019] Furthermore, the ratio of plant material to water is 1:50 - 70 g / mL.

[0020] Furthermore, the steaming temperature is 90 - 100 °C and the steaming time is 40 - 90 min.

[0021] Preferably, the ratio of Coptis chinensis dye to the steaming solution is 1:70 g / mL, the steaming temperature is 100 °C, and the steaming time is 40 min. Subsequently, the steaming solution is naturally cooled to room temperature and filtered to obtain Coptis chinensis dye solution; the ratio of Sappanwood dye to the steaming solution is 1:60, the steaming temperature is 100 °C, and the steaming time is 90 min. Subsequently, the steaming solution is naturally cooled to room temperature and filtered to obtain Sappanwood dye solution; the ratio of Gardenia jasminoides Ellis dye to the steaming solution is 1:50, the steaming temperature is 90 °C, and the steaming time is 40 min. Subsequently, the steaming solution is naturally cooled to room temperature and filtered to obtain Gardenia jasminoides Ellis dye solution.

[0022] Furthermore, the method for improving the color fastness of plant dyes includes the following steps:

[0023] S1. Disperse the nano metal oxide in water to obtain a fixing solution;

[0024] S2. Uniformly coat the fixing solution on the calligraphy and painting paper dyed with plant dyes.

[0025] Preferably, disperse the nano metal oxide in water by ultrasonic treatment.

[0026] Preferably, the mass fraction of the nano metal oxide in the fixing solution is 0.2 - 0.4%.

[0027] Furthermore, the coating amount of the fixing solution is 0.010 - 0.030 mL / cm 2 .

[0028] Preferably, use a coater to uniformly apply the fixing solution on the calligraphy and painting paper dyed with plant dyes by the coating method.

[0029] A fixing agent for improving the color fastness of plant dyes, the fixing agent comprising at least one of nano metal oxide and nano silica.

[0030] Preferably, the nano metal oxide comprises at least one of nano zinc oxide and nano titanium dioxide.

[0031] Preferably, the particle size of the nano metal oxide is 10 - 200 nm.

[0032] The prior art mainly focuses on the anti-ultraviolet aging research in the paper conservation of cultural relics, emphasizing the strength retention, anti-ultraviolet ability and antibacterial performance of paper, preventing problems such as oxidative degradation and strength decline of paper caused by ultraviolet rays, so as to extend the lifespan of the paper of cultural relics. The purpose of this application is to address the color fastness problem of plant dyes on dyed calligraphy and painting paper after calligraphy and painting are dyed. Through the color fixation effect of nano-metal oxides, the anti-fading performance of dyed calligraphy and painting paper under environments such as light, ultraviolet radiation, and dry-heat aging is significantly improved, maintaining the visual effect and artistic quality of calligraphy and painting.

[0033] This application combines nano-metal oxides with plant dyes (natural pigments) for the first time, solving the problem that the traditional soybean milk color fixation method has an unsatisfactory effect on dyed calligraphy and painting paper, and providing a brand-new solution for the protection and optimization of colored calligraphy and painting paper. This application clarifies the coating process of the color fixation liquid and the steaming conditions of plant dyes, ensuring the uniform distribution and stability of nano-metal oxides on dyed calligraphy and painting paper, and improving the feasibility of practical applications.

[0034] This invention uses nano-metal oxides (nano-zinc oxide, nano-silica, nano-titanium dioxide) as color fixatives. Compared with traditional color fixatives such as soybean milk, gelatin, and alum, these materials of this invention have excellent light shielding effects, especially good shielding effects on both ultraviolet UVA and UVB. They can effectively protect the colors of calligraphy and painting paper dyed with Coptis chinensis, Caesalpinia sappan, and Gardenia jasminoides Ellis, effectively alleviating the fading phenomenon of calligraphy and painting paper dyed with Coptis chinensis, Caesalpinia sappan, and Gardenia jasminoides Ellis under changes in the external environment, and at the same time increasing the diversity of color fixatives in the field of calligraphy and painting paper. In addition, nano-zinc oxide, nano-silica, and nano-titanium dioxide as color fixatives are not only non-toxic, odorless, and chemically stable, but also have antibacterial effects.

[0035] This invention tests the light stability and thermal stability of the colors of calligraphy and painting paper dyed with different groups of Coptis chinensis, Caesalpinia sappan, and Gardenia jasminoides Ellis through three methods: dry-heat aging, visible light irradiation, and ultraviolet radiation, simulating the changes in different external environments through multiple ways, and more scientifically verifying the color fixation effects of different groups of color fixatives.

[0036] Compared with the prior art, the beneficial effects of the technical solution of this invention are:

[0037] 1. Significantly improve the color fastness of plant dyes. This invention uses nano-metal oxides as color fixatives, significantly improving the color fastness of calligraphy and painting paper dyed with plant dyes such as Coptis chinensis, Caesalpinia sappan, and Gardenia jasminoides Ellis. After treatments such as dry-heat aging, visible light irradiation, and ultraviolet radiation, the color difference is significantly lower than that of samples treated with traditional color fixatives (such as soybean milk water). Compared with traditional color fixatives, for calligraphy and painting paper dyed with Coptis chinensis and fixed with nano-zinc oxide, after ultraviolet radiation treatment, the color difference decreases from 6.4 to 3.1, and the color fastness increases from level 2 to level 3, with a decrease of 51.56%. Similar effects are also reflected in calligraphy and painting paper dyed with Caesalpinia sappan and Gardenia jasminoides Ellis.

[0038] 2. Anti-aging and light irradiation resistance. The test results of dry heat aging and visible light irradiation show that nano-metal oxides can effectively slow down the fading phenomenon of calligraphy and painting paper, extend the service life of the paper, and maintain color stability especially during long-term storage and display. After dry heat aging, the color difference of gardenia-dyed calligraphy and painting paper fixed with nano-zinc oxide decreased from 5.90 to 1.41, and the color fastness increased from grade 3 to grade 5, with a decrease of 76.10%. After visible light irradiation treatment, the color difference of gardenia-dyed calligraphy and painting paper fixed with nano-silica decreased from 2.88 to 1.46, and the color fastness increased from grade 4 to grade 5, with a decrease of 49.31%. The above results fully prove the effectiveness and superiority of the present invention in improving the color fastness of plant dyes, especially in anti-aging and light irradiation resistance. Description of the Drawings

[0039] Figure 1 Is a physical photo of coptis-dyed calligraphy and painting paper after being treated by different methods;

[0040] Figure 2 Is a physical photo of sappanwood-dyed calligraphy and painting paper after being treated by different methods;

[0041] Figure 3 Is a physical photo of gardenia-dyed calligraphy and painting paper after being treated by different methods. Detailed Embodiments

[0042] The present invention will be further described below in conjunction with the drawings in the specification and specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0043] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0044] Example 1

[0045] The preparation of coptis-dyed calligraphy and painting paper in the present invention, the preparation of nano-zinc oxide fixing solution, and dry heat aging, visible light irradiation, and ultraviolet radiation treatment include the following steps:

[0046] (1) Add 20 g of coptis dye (20 - 80 mesh) to 1400 mL of distilled water at one time, and cook it in a water bath. The cooking temperature is 100 °C, and the cooking time is 40 min. After cooking, cool the cooking liquid to room temperature naturally under light-shielded conditions, and then filter the cooking liquid to obtain coptis dye solution for standby;

[0047] (2) Dye the cut calligraphy and painting paper (17×17 cm of pure bark raw rice paper) by the dragging method in the coptis extract. Lay the dyed calligraphy and painting paper flat on a plastic board and dry it naturally under light-shielded conditions to obtain coptis-dyed calligraphy and painting paper;

[0048] (3) Take 0.3 g of nano-zinc oxide and disperse it evenly in 100 mL of distilled water by ultrasonic treatment for 30 min to obtain a nano-zinc oxide fixing solution.

[0049] (4) Use a coater to evenly apply the nano-zinc oxide fixing solution to the Coptis chinensis stained calligraphy and painting paper, with a coating amount of 0.030 mL / cm 2 . Leave the coated Coptis chinensis stained calligraphy and painting paper to dry naturally under light-proof conditions to obtain nano-zinc oxide reinforced Coptis chinensis stained calligraphy and painting paper.

[0050] Examples 2 - 9

[0051] The technical solutions of Examples 2 - 9 are similar to those of Example 1, and the specific differences are shown in Table 1.

[0052] Table 1 Technical solutions of Examples 2 - 9

[0053]

[0054]

[0055] Comparative Example 1

[0056] Weigh 10 g of organic soybeans, soak them in cold water for 24 h and then take them out. Put the soaked soybeans and 200 mL of water into a juicer to extract juice for 30 min. Filter the extracted soybean milk with a filter screen and boil it for 45 - 60 min. After cooling to room temperature, filter it for standby. Use a coater to evenly apply the obtained soybean milk to the calligraphy and painting paper stained with Coptis chinensis, Sappanwood and Gardenia jasminoides Ellis, with a coating amount of 0.025 mL / cm 2 . Leave the coated stained calligraphy and painting paper to dry naturally under light-proof conditions to obtain soybean milk reinforced calligraphy and painting paper stained with Coptis chinensis, Sappanwood and Gardenia jasminoides Ellis.

[0057] Detection method

[0058] 1. Dry heat aging treatment: Refer to GB / T 464 - 2008, and conduct aging treatment on the stained calligraphy and painting paper treated with nano-metal oxides in a drying oven at an aging temperature of 105 °C for 2 d for standby.

[0059] 2. Visible light irradiation: Conduct visible light irradiation treatment on the stained calligraphy and painting paper treated with nano-metal oxides under an artificial xenon lamp (300 - 1000 nm) with an aging intensity of 300 mw / cm 2 . The treatment time is 20 min for standby.

[0060] 3. Ultraviolet radiation: Conduct ultraviolet radiation treatment on the stained calligraphy and painting paper treated with nano-metal oxides under an ultraviolet lamp (365 nm) with an aging intensity of 300 mw / cm 2 . The treatment time is 20 min for standby.

[0061] 4. Index Evaluation

[0062] (1) Equilibrate the dyed calligraphy and painting paper treated with dry heat aging, visible light irradiation, and ultraviolet radiation for more than 4 h under the conditions specified in GB / T 10739-2002;

[0063] (2) Use a whiteness meter to measure the L, a, and b values of the Coptis chinensis, Sappanwood, and Gardenia jasminoides Ellis dyed calligraphy and painting paper corresponding to the blank control group, traditional soybean milk water color fixing group, nano-titanium dioxide color fixing group, nano-silica color fixing group, and nano-zinc oxide color fixing group, respectively, after 2 d of dry heat aging, 20 min of visible light irradiation, and 20 min of ultraviolet radiation;

[0064] (3) Refer to "Uniform Color Space and Color Difference Formula" (GB / T 7921-2008), and the color difference calculation formula is as follows:

[0065]

[0066] Among them, ΔE is the color difference change value, ΔL is the lightness change, Δa is the red-green difference (a is positive for red and negative for green), and Δb is the yellow-blue difference (b is positive for yellow and negative for blue).

[0067] (4) There is currently no unified evaluation method and standard for the color fastness of calligraphy and painting paper. Therefore, this invention refers to "Textiles - Tests for color fastness - Color fastness to artificial light: Xenon arc" (GB / T 8427-2019) to formulate the test method and evaluation standard for the color fastness of colored calligraphy and painting paper to dry heat aging and artificial light, and based on this, evaluate the effect of the color fixing agent of this invention. The irradiance uniformity of the artificial xenon lamp and ultraviolet lamp is affected by various factors. For example, the distance difference between the exposed specimen and the artificial xenon lamp and ultraviolet lamp will affect the exposure uniformity; the dust on the optical system and the test chamber wall will also affect the exposure uniformity; the type and quantity of the exposed specimen will also affect the exposure uniformity. Therefore, these influencing factors also need to be restricted in the test to meet the exposure uniformity of the exposed specimen. It should be ensured that the irradiance difference at any position in the specimen exposure area of the artificial xenon lamp and ultraviolet lamp does not exceed ±10% of the average value when the exposure experiment is completed. The exposure time is 20 min, and the exposure intensity is 300 mw / cm 2 , and store it in the dark for 24 h after completion. Use a whiteness meter to detect the L, a, and b values of the specimen, and calculate the color difference value through the color difference formula. According to the size of the color difference value, grade and evaluate the color fastness of the specimen as follows:

[0068] Grade 1: Color difference 9.00 - 15.00

[0069] Grade 2: Color difference 6.00 - 9.00

[0070] Grade 3: Color difference 3.00 - 6.00

[0071] Level 4: Color difference 1.50 - 3.00

[0072] Level 5: Color difference 0 - 1.50

[0073] Test results

[0074] Table 1 Color difference values of calligraphy and painting paper dyed with Coptis chinensis after being treated by different methods

[0075]

[0076] Combined with Table 1 and Figure 1 the results, it can be seen that the color differences of the calligraphy and painting paper dyed with Coptis chinensis after being treated by dry heat aging, visible light irradiation, and ultraviolet radiation using the nano-zinc oxide, nano-titanium dioxide, and nano-silica fixing agents adopted in the present invention are all smaller than those of the traditional fixing agent Comparative Example 1 and the blank control group. Among them, in Example 3 under dry heat aging conditions, compared with Comparative Example 1, the color difference value of the calligraphy and painting paper dyed with Coptis chinensis decreased from 8.13 to 3.80, with a decrease rate of 53.26%, and the color fastness increased from level 2 to level 3; in Example 2 under visible light irradiation, compared with Comparative Example 1, the color difference value of the calligraphy and painting paper dyed with Coptis chinensis decreased from 3.07 to 2.17, with a decrease rate of 29.32%, and the color fastness increased from level 3 to level 4; in Example 2 under ultraviolet radiation, compared with Comparative Example 1, the color difference value of the calligraphy and painting paper dyed with Coptis chinensis decreased from 6.40 to 3.10, with a decrease rate of 51.56%, and the color fastness increased from level 2 to level 3.

[0077] Table 2 Color difference values of calligraphy and painting paper dyed with Sappanwood after being treated by different methods

[0078]

[0079] From Table 2 and Figure 2 the results, it can be seen that the color differences of the calligraphy and painting paper dyed with Sappanwood after being treated by visible light irradiation and ultraviolet radiation using the nano-zinc oxide, nano-titanium dioxide, and nano-silica fixing agents adopted in Examples 4 - 6 of the present invention are all smaller than those of the traditional fixing agent Comparative Example 1 and the blank control group. Among them, in Example 5 under visible light irradiation, compared with Comparative Example 1, the color difference value of the calligraphy and painting paper dyed with Sappanwood decreased from 9.23 to 4.80, with a decrease rate of 48.00%, and the color fastness increased from level 1 to level 3; in Example 5 under ultraviolet irradiation, compared with Comparative Example 1, the color difference value of the calligraphy and painting paper dyed with Sappanwood decreased from 10.03 to 5.47, with a decrease rate of 45.46%, and the color fastness increased from level 1 to level 3.

[0080] Table 3 Color difference values of calligraphy and painting paper dyed with Gardenia jasminoides Ellis after being treated by different methods

[0081]

[0082] From Table 3 and Figure 3It can be seen that the color differences of the nano-zinc oxide, nano-titanium dioxide, and nano-silica fixing agents used in Examples 7 to 9 of the present invention after dry heat aging and visible light irradiation treatment on gardenia-dyed calligraphy and painting paper are all smaller than those of the traditional fixing agent soy milk group (Comparative Example 1) and the blank control group. Among them, in Example 7, compared with Comparative Example 1 under dry heat aging, the color difference value of the gardenia-dyed calligraphy and painting paper decreased from 5.90 to 1.41, a decrease of 76.10%, and the color fastness increased from grade 3 to grade 5; in Example 8, compared with Comparative Example 1 under visible light irradiation, the color difference value of the gardenia-dyed calligraphy and painting paper decreased from 2.88 to 1.46, a decrease of 49.31%, and the color fastness increased from grade 4 to grade 5; in Example 8, compared with Comparative Example 1 under ultraviolet radiation, the color difference value of the gardenia-dyed calligraphy and painting paper decreased from 6.61 to 4.43, a decrease of 32.98%, and the color fastness increased from grade 2 to grade 3.

[0083] In summary, the nano-metal oxides (nano-titanium dioxide, nano-silica, nano-zinc oxide) used in the present invention as fixing agents have good fixing effects. Compared with the traditional fixing agent soy milk water, the color fastness of calligraphy and painting paper dyed with Coptis chinensis, Sappanwood, and Gardenia jasminoides Ellis has been greatly improved. Compared with the traditional fixing agent soy milk, the color of calligraphy and painting paper dyed with Coptis chinensis, Sappanwood, and Gardenia jasminoides Ellis has been greatly protected, effectively alleviating the fading phenomenon of calligraphy and painting paper dyed with Coptis chinensis, Sappanwood, and Gardenia jasminoides Ellis when external conditions change. The fixing method provided by the present invention has non-toxic and odorless fixing agent materials, simple fixing steps, and excellent fixing effects, and has broad application prospects in the field of calligraphy and painting paper such as rice paper.

[0084] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for improving the color fastness of plant dyes, characterized in that: The color fixing agent used includes at least one of nano metal oxide and nano silicon dioxide.

2. The method for improving the color fastness of plant dyes according to claim 1, characterized in that: The nano metal oxide includes at least one of nano zinc oxide and nano titanium dioxide.

3. The method for improving the color fastness of plant dyes according to claim 1, characterized in that: The particle size of the nano metal oxide is 10-200 nm.

4. The method for improving the color fastness of plant dyes according to claim 1, characterized in that: The plant dye comprises at least one of coptis root, sappan wood and gardenia.

5. The method for improving the color fastness of plant dyes according to claim 1, characterized in that: After the fixing agent is prepared into a fixing solution, the coating amount of the fixing solution is 0.010-0.030 mL / cm 2 .

6. The method for improving the color fastness of plant dyes according to claim 1, characterized in that: Improve the color fastness of plant dyes on calligraphy and painting papers.

7. The method for improving the color fastness of plant dyes according to claim 6, characterized in that: The painting and calligraphy paper dyed with plant dyes is dyed by the following method: S1, crushing and screening the plant material used as dye, boiling it in water, and filtering it to obtain a dye solution; S2. Dyeing calligraphy and painting paper with dye solution.

8. The method for improving the color fastness of plant dyes according to claim 7, characterized in that: The ratio of plant material to water is 1:50-70 g / mL.

9. The method for improving the color fastness of plant dyes according to claim 7, characterized in that: The cooking temperature is 90-100°C and the cooking time is 40-90 minutes.

10. A color fixing agent for improving the color fastness of plant dyes, characterized in that: The color fixing agent includes at least one of nano metal oxide and nano silicon dioxide.

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