A confined heat-resistant flavonoid plant dye and its preparation method

Abstract

This invention discloses a confined heat-resistant flavonoid plant dye and its preparation method. The confined heat-resistant flavonoid plant dye is formed by combining flavonoid plant dyes with modified montmorillonite. The flavonoid plant dyes enter the interlayer structure of metal ion-modified montmorillonite through interlayer intercalation and are confined and fixed, further constructing an antioxidant functional layer on its surface. This invention modifies montmorillonite with metal cations, expanding the interlayer spacing and forming a stable pillar structure, providing a stable environment for the effective intercalation of flavonoid plant dyes. Simultaneously, coordination between the metal cations and flavonoid plant dye molecules enhances the fixation of dye molecules within the interlayer structure. Through the synergistic effect of the interlayer confinement structure and the antioxidant, the thermal motion of dye molecules is inhibited, and free radical reactions during thermal oxidation are terminated, resulting in an initial decomposition temperature of the confined heat-resistant flavonoid plant dye that is more than 30°C higher than that of the untreated dye.

Description

Technical Field

[0001] This invention relates to the field of plant dye preparation, specifically to a confined heat-resistant flavonoid plant dye and its preparation method. Background Technology

[0002] Flavonoid plant dyes are natural pigments extracted from the flowers, leaves, fruits, roots, and stems of plants. They possess the advantages of being natural, environmentally friendly, non-toxic, harmless, and biodegradable. They also have certain antioxidant and antibacterial properties, aligning with the green and healthy consumption trend in industries such as textiles, food, and cosmetics, and have broad application prospects. However, most flavonoid plant dyes struggle to meet heat resistance requirements in high-temperature processing or application scenarios, such as dyeing synthetic fibers like polyester at around 130℃, heat transfer printing at approximately 200℃, coloring engineering plastics at 200–250℃, and high-temperature curing coatings.

[0003] Currently, methods for improving the heat resistance of plant dyes, such as metal complexation modification, have problems such as easy aggregation of complexes and dye migration; microcapsule encapsulation modification has the risk of high-temperature rupture and insufficient long-term stability; polymer grafting modification has complex processes and easily destroys the natural conjugated structure and functionality of flavonoid dyes. None of these methods can fundamentally solve the problem of poor thermal stability of flavonoid plant dyes under high-temperature conditions. Summary of the Invention

[0004] To address the problems of thermal decomposition, hue degradation, and performance instability of flavonoid plant dyes during high-temperature processing, the present invention aims to provide a confined heat-resistant flavonoid plant dye and its preparation method, which effectively improves the structural stability of flavonoid plant dyes under high-temperature processing conditions and high-temperature use environments.

[0005] This invention first provides a method for preparing a confined, heat-resistant flavonoid plant dye, comprising the following steps: (1) Add metal ion modified montmorillonite to a flavonoid plant dye solution, stir to allow the plant dye molecules to fully intercalate or adsorb into the montmorillonite, let it stand for aging, filter, separate and dry after the reaction to obtain the interlayer confined hybrid complex.

[0006] In metal ion modified montmorillonite, the metal ions are selected from Al. 3+ Mg 2+ Zn 2+ One of them, preferably Al 3+ Furthermore, the metal ion exchange capacity is 0.6 to 1.0 times the total ion exchange capacity of montmorillonite. The flavonoid dyes are selected from one or more of the following plant dyes: Sophora japonica flower dye, Scutellaria baicalensis flower dye, Cotinus coggygria flower dye, and mulberry leaf dye.

[0007] Natural montmorillonite has small and unstable interlayer spacing, with Na being the main interlayer component. + Equivalent exchangeable cations. Introduction of Al 3+ Mg 2+ Zn 2+ After the metal ions are introduced, a pillared structure or a strong charge-compensating structure is formed, which expands the interlayer spacing, improves the thermal stability of the interlayer space, and reduces the risk of interlayer collapse at high temperatures. Secondly, the ortho- and tho-diphenol structures in flavonoid dyes all have good coordination ability and can form coordination bonds with metal ions to form a stable ternary structure of montmorillonite-metal cation-flavonoid dye molecules. This improves the intramolecular stability of the dye molecules and their anchoring ability in the interlayer, and inhibits migration and volatilization at high temperatures.

[0008] The mass ratio of flavonoid plant dyes to metal ion-modified montmorillonite is 1:3 to 1:5.

[0009] The stirring conditions were as follows: stirring at 60-80℃ for 4-8 hours; aging time: 12-14 hours; and drying conditions: vacuum drying at 50-60℃ for 10-12 hours.

[0010] (2) The interlayer confinement hybrid complex is treated with a surface activator to introduce active functional groups on its surface, thereby obtaining a surface-activated interlayer confinement hybrid complex.

[0011] Before constructing the antioxidant functional layer, it is preferable to use a silane coupling agent to perform surface activation treatment on the interlayer confined hybrid composite. This introduces active functional groups such as amino and epoxy groups onto the montmorillonite surface, allowing the antioxidant to be chemically anchored to the composite surface through covalent bonds, significantly improving the grafting density and bonding strength of the antioxidant layer. Specifically, the interlayer confined hybrid composite is dispersed in an ethanol mixed solvent, and 1-3 wt% of the interlayer confined hybrid composite with a silane coupling agent is added. The mixture is stirred at 50℃-80℃ for 3-6 h, and after washing and drying, the surface-activated interlayer confined hybrid composite is obtained.

[0012] The surfactant is a silane coupling agent selected from at least one of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), and γ-methacryloyloxypropyltrimethoxysilane (KH570).

[0013] (3) The surface-activated interlayer confined hybrid complex was added to the hindered phenolic antioxidant solution, stirred and reacted to form a surface antioxidant functional layer, filtered, vacuum dried, pulverized to a particle size ≤ 5 μm, and sieved to obtain confined heat-resistant flavonoid plant dye.

[0014] The amount of hindered phenolic antioxidant added is 1% to 10% of the mass of the surface-activated interlayer confined hybrid complex.

[0015] Optionally, the hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), and 2,6-di-tert-butyl-p-cresol (antioxidant 264).

[0016] The stirring reaction temperature is 40~60℃, and the reaction time is 1~3 h.

[0017] Vacuum drying involves drying at 50-60℃ for 10-12 hours in a vacuum drying oven, followed by heating to 120-150℃ for 2-4 hours to further stabilize the coordination between metal ions and dye molecules.

[0018] The present invention further provides a confined heat-resistant flavonoid plant dye prepared by the above preparation method. Thermogravimetric analysis shows that the initial decomposition temperature of the confined heat-resistant flavonoid plant dye is more than 30°C higher than that of the untreated flavonoid plant dye.

[0019] The technical principles and beneficial effects of this invention are as follows: During high-temperature processing or use, flavonoid plant dyes are prone to thermal oxidative degradation. The degradation mechanism typically involves a chain reaction process initiated by free radicals, including phenolic hydroxyl oxidation, conjugated structure breakage, and molecular rearrangement. This invention modifies montmorillonite with metal cations, expanding the interlayer spacing and forming a stable pillared structure. This improves the structural and thermal stability of the interlayer space, providing a stable confined environment for the effective intercalation of flavonoid plant dyes, thereby enhancing the spatial confinement of dye molecules. Simultaneously, the metal cations can coordinate with the phenolic hydroxyl groups in the flavonoid plant dye molecules, enhancing the fixation of dye molecules in the interlayer structure and reducing their migration and desorption risks under high-temperature conditions.

[0020] While interlayer confinement structures can restrict the thermal motion of dye molecules to some extent, they cannot completely suppress free radical reactions involving oxygen. Therefore, constructing an antioxidant functional layer on the outer surface of layered silicates can preferentially capture free radicals in the early stages of material heating, terminate chain reactions, reduce the attack of reactive oxygen species on dye molecules, and improve the stability of flavonoid plant dyes through a synergistic mechanism of outer layer blocking and inner layer confinement.

[0021] Natural antioxidants typically have low thermal decomposition temperatures. At high temperatures, they not only lose their antioxidant activity but may also produce colored degradation products, affecting the color of dyes. This invention selects hindered phenolic antioxidants to construct the outer antioxidant layer. Their thermal decomposition temperatures are all above 300℃, and they can still maintain a free radical capture efficiency of over 90% even under long-term heating at 200℃, meeting the stability requirements under high-temperature conditions. Furthermore, they have a light color and do not affect the luster of the dye.

[0022] This invention utilizes the synergistic effect of interlayer confinement structure and hindered phenolic antioxidants to inhibit the thermal motion and structural breakage of dye molecules on the one hand, and terminate the free radical chain reaction during thermo-oxidative aging on the other hand, thereby increasing the initial decomposition temperature of the dye by more than 30°C compared with untreated flavonoid plant dyes.

[0023] The confined heat-resistant flavonoid plant dyes prepared by this invention effectively improve the structural stability of flavonoid plant dyes under high-temperature processing and high-temperature use conditions, while significantly enhancing their anti-aging and anti-fading capabilities under long-term light exposure, greatly improving the overall stability of the dyes, breaking through the application limitations of flavonoid plant dyes under high-temperature and long-term light exposure conditions, and broadening the applicable scenarios and application fields of flavonoid plant dyes. Detailed Implementation

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0026] The present invention will be further described in detail below with reference to the embodiments: In the following examples, the montmorillonite used was sodium montmorillonite, purchased from Lingshou Xuyang Mining Co., Ltd.; the plant dyes were all from Changzhou Meisheng Biomaterials Co., Ltd.; the silane coupling agents KH550, KH560, and KH570 were purchased from Hubei Xinlantian New Material Co., Ltd.; and the antioxidants 1010, 1076, and 264 were purchased from Jiangsu Jiyi Chemical Group Co., Ltd.

[0027] In the following specific embodiments of the present invention, a thermogravimetric analyzer was used under a nitrogen atmosphere and a heating rate of 10°C / min to test the initial thermal decomposition temperature (DTG main decomposition peak temperature) of the plant dyes and the dyes obtained in each example and comparative example.

[0028] Example 1

[0029] A method for preparing a confined, heat-resistant mulberry leaf plant dye includes the following steps: Al 3+ Modified montmorillonite: Preparation of a 5% (w / w) montmorillonite slurry: Add montmorillonite to deionized water and stir at 70°C for 2 hours to form a uniform suspension. Add Al to this slurry. 3+ An aqueous solution of AlCl3, with an amount 1.0 times the cation exchange capacity of montmorillonite, was added and stirred for 4 h. The mixture was then filtered and washed with deionized water until the filtrate was free of chloride ions. After filtration, the filtrate was dried under vacuum at 60°C for 12 h to obtain AlCl3. 3+ Modified montmorillonite, for later use.

[0030] Plant dye adsorption: Weigh 20 parts of mulberry leaf plant dye and dissolve it in 980 parts of a 40% (w / w) ethanol aqueous solution. Adjust the pH to 5-6 and stir to form a homogeneous plant dye solution. Add 60 parts of Al... 3+ Modified montmorillonite was slowly added to the plant dye solution and stirred at 60°C for 8 h, followed by aging at rest for 12 h. After the reaction was completed, the mixture was filtered, separated, and dried to obtain the interlayer confined hybrid complex. The adsorption capacity of the mulberry leaf plant dye was calculated to be 20.8% after weighing.

[0031] Surface activation: The obtained interlayer confinement hybrid complex was dispersed in 1000 parts of 95% ethanol, and 2 wt% KH560 of the interlayer confinement hybrid complex was added. The pH of the system was adjusted to 4-5 with acetic acid. The mixture was stirred at 70℃ for 4 h. After the reaction was completed, the mixture was filtered and separated, washed twice with anhydrous ethanol, and dried under vacuum at 60℃ for 6 h to obtain the surface-activated interlayer confinement hybrid complex.

[0032] Construction of antioxidant layer: Weigh 1 part of antioxidant 1010, dissolve it in 999 parts of ethanol, add the above activated interlayer confined hybrid complex and react at 50℃ for 2 h. After the reaction is completed, wash with deionized water to obtain filter cake. Vacuum drying: The filter cake was vacuum dried at 60℃ for 12 h; then vacuum dried at 120℃ for 4 h to remove interlayer water.

[0033] Pulverization: The dye particle size was controlled to 5 μm by using a ball mill to obtain confined heat-resistant flavonoid plant dyes.

[0034] Thermogravimetric analysis showed that the initial thermal decomposition temperature of confined heat-resistant mulberry leaf plant dyes was 36°C higher than that of mulberry leaf plant dyes.

[0035] Example 2

[0036] A method for preparing a confined, heat-resistant dye from Scutellaria baicalensis includes the following steps: Al 3+Modified montmorillonite: Add AlCl3 aqueous solution to 5% montmorillonite slurry, so that the added Al... 3+ The dosage is 0.8 times the cation exchange capacity of montmorillonite. Other procedures are the same as in Example 1.

[0037] Adsorption of plant dyes: 10 parts of Scutellaria baicalensis plant dye were weighed and dissolved in 990 parts of 50% ethanol aqueous solution. The pH was adjusted to 5-6, and the solution was stirred to form a homogeneous plant dye solution. 40 parts of modified montmorillonite were slowly added to the plant dye solution, and the mixture was stirred at 70℃ for 6 h, followed by aging at rest for 12 h. After the reaction was completed, the mixture was filtered, separated, and vacuum dried at 60℃ for 12 h to obtain the interlayer confined hybrid complex. The adsorption capacity of the plant dye was calculated to be 18.0% after weighing.

[0038] Surface activation: The obtained interlayer confinement hybrid complex was dispersed in 1000 parts by mass of 95% ethanol, and 1 wt% of KH570 of the interlayer confinement hybrid complex was added. The pH of the system was adjusted to 4-5 with acetic acid, and the reaction was stirred at 60℃ for 5 h. After the reaction was completed, the mixture was filtered and separated, washed twice with anhydrous ethanol, and dried under vacuum at 60℃ for 6 h to obtain the surface-activated interlayer confinement hybrid complex.

[0039] Construction of antioxidant layer: Weigh 0.3 parts of antioxidant 1076, dissolve it in 999.7 parts of ethanol, add the above activated interlayer confined hybrid complex and react at 40℃ for 3 h. After the reaction is completed, wash with deionized water to obtain filter cake. Vacuum drying: The filter cake was vacuum dried at 60℃ for 12 h; then vacuum dried at 135℃ for 3 h to remove interlayer water.

[0040] Pulverization: The dye particle size was controlled to 5 μm by using a ball mill to obtain confined heat-resistant flavonoid plant dyes.

[0041] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the confined heat-resistant Scutellaria baicalensis plant dye was 33°C higher than that of the original Scutellaria baicalensis plant dye.

[0042] Example 3

[0043] A method for preparing a confined heat-resistant dye from the smoke tree plant includes the following steps: Al 3+ Modified montmorillonite: Add AlCl3 aqueous solution to 5% montmorillonite slurry, so that the added Al³⁺… + The dosage is 0.9 times the cation exchange capacity of montmorillonite. Other operations are the same as in Example 1.

[0044] Adsorption of plant dyes: 15 parts of *Cotinus coggygria* plant dye were weighed and dissolved in 985 parts of 40% ethanol. The pH was adjusted to 5-6, and the mixture was stirred to form a homogeneous plant dye solution. 55 parts of modified montmorillonite were slowly added to the plant dye solution and stirred at 80℃ for 5 h, followed by aging at rest for 12 h. After the reaction was completed, the mixture was filtered, separated, and dried to obtain the interlayer confined hybrid complex. The adsorption capacity of the plant dye was calculated to be 18.6% after weighing.

[0045] Surface activation: The obtained interlayer confinement hybrid complex was dispersed in 1000 parts by mass of 95% ethanol, and 2 wt% of KH550 of the interlayer confinement hybrid complex was added. The pH of the system was adjusted to 4-5 with acetic acid, and the reaction was stirred at 50℃ for 6 h. After the reaction was completed, the mixture was filtered and separated, washed twice with anhydrous ethanol, and dried under vacuum at 60℃ for 6 h to obtain the surface-activated interlayer confinement hybrid complex.

[0046] Construction of antioxidant layer: Weigh 1.5 parts of antioxidant 264, dissolve it in 998.5 parts of ethanol, add the above activated interlayer confined hybrid complex, and react at 60℃ for 1 h. After the reaction is complete, wash with deionized water to obtain filter cake. Vacuum drying: The filter cake was vacuum dried at 60℃ for 12 h; then vacuum dried at 140℃ for 3 h to remove interlayer water.

[0047] Pulverization: The dye particle size was controlled to 5 μm by using a ball mill to obtain confined heat-resistant flavonoid plant dyes.

[0048] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the confined smoke tree heat-resistant plant dye was 33°C higher than that of the smoke tree plant dye.

[0049] Example 4

[0050] A method for preparing a confined, heat-resistant Sophora japonica plant dye includes the following steps: Al 3+ Modified montmorillonite: Add AlCl3 aqueous solution to 5% montmorillonite slurry, so that the added Al³⁺… + The dosage is 0.9 times the cation exchange capacity of montmorillonite. Other operations are the same as in Example 1.

[0051] Adsorption of plant dyes: 30 parts of Sophora japonica flower dye were weighed and dissolved in 970 parts of 40% ethanol. The pH was adjusted to 5-6, and the mixture was stirred to form a homogeneous plant dye solution. 100 parts of modified montmorillonite were slowly added to the plant dye solution and stirred at 75℃ for 5.5 h, followed by aging at rest for 12 h. After the reaction was completed, the mixture was filtered, separated, and dried to obtain the interlayer confined hybrid complex. The adsorption capacity of the plant dye was calculated to be 21.2% after weighing.

[0052] Surface activation: The obtained interlayer confinement hybrid complex was dispersed in 1000 parts of 95% ethanol aqueous solution, and 3 wt% KH560 of the interlayer confinement hybrid complex was added. The pH of the system was adjusted to 4-5 with acetic acid. The reaction was stirred at 8°C for 3 h. After the reaction was completed, the mixture was filtered and separated, washed twice with anhydrous ethanol, and dried under vacuum at 60°C for 6 h to obtain the surface-activated interlayer confinement hybrid complex.

[0053] Construction of antioxidant layer: Weigh 0.5 parts of antioxidant 1010, dissolve it in 999.5 parts of ethanol, add the above activated interlayer confined hybrid complex and react at 40℃ for 3 h. After the reaction is complete, wash with deionized water to obtain filter cake. Vacuum drying: The filter cake was vacuum dried at 60℃ for 12 h; then vacuum dried at 150℃ for 2 h to remove interlayer water.

[0054] Pulverization: The dye particle size was controlled to 5 μm by using a ball mill to obtain a confined heat-resistant plant dye.

[0055] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the confined heat-resistant Sophora japonica plant dye was 32℃ higher than that of the mulberry leaf plant dye.

[0056] Comparative Example 1

[0057] The difference between this example and Example 1 is that the montmorillonite was not modified with metal ions.

[0058] After adsorption of the dye, the adsorption amount of plant dye was calculated to be 11.5%, which is much lower than that in Example 1. Thermogravimetric analysis showed that the initial thermal decomposition temperature of the mulberry leaf plant dye treated in this example increased by 18°C. This indicates that without metal ion modification, the interlayer structure of montmorillonite has low stability, insufficient confinement effect, and small interlayer spacing. Consequently, less plant dye is adsorbed between the interlayer regions, and more is adsorbed on the montmorillonite surface. Furthermore, without metal coordination bonds for reinforcement, the plant dye molecules are easily degraded.

[0059] Comparative Example 2

[0060] The difference between this example and Example 1 is that surface activation and antioxidant layer construction were not performed.

[0061] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the treated mulberry leaf dye increased by 21°C. This indicates that interlayer confinement of the mulberry leaf dye with modified montmorillonite can improve its thermal stability; however, the presence of free radicals still leads to increased degradation, and its effect is not as good as that of Example 1.

[0062] Comparative Example 3

[0063] The difference between this example and Example 1 is that no surface activation treatment was performed before the antioxidant layer was constructed.

[0064] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the treated mulberry leaf plant dye increased by 24℃. This indicates that the montmorillonite surface was not activated, resulting in low adsorption of antioxidants and limited enhancement of the plant dye's heat resistance.

[0065] Comparative Example 4

[0066] The difference between this example and Example 1 is that the antioxidant layer construction process involves directly physical blending one part of antioxidant 1010 with the surface-activated interlayer confined hybrid complex. The remaining steps are the same as in Example 1.

[0067] Thermogravimetric analysis showed that the initial thermal decomposition temperature of the confined heat-resistant mulberry leaf plant dyes was 25°C higher than that of mulberry leaf plant dyes. Direct physical blending of antioxidants can alleviate the thermal oxidative degradation of mulberry leaf plant dyes under high-temperature conditions to some extent, but it only captures free radicals on the surface of the hybrid dyes and does not specifically capture free radicals generated by the thermal degradation of the dyes between the hybrid dye layers. Some antioxidants did not even come into contact with the hybrid plant dyes. Therefore, the effect of increasing the thermal decomposition temperature was not as good as in Example 1.

[0068] Table 1 Results of Increased Thermal Decomposition Temperature of Plant Dyes

[0069] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

Claims

1. A method for preparing a confined, heat-resistant flavonoid plant dye, characterized in that, Includes the following steps: (1) Add metal ion modified montmorillonite to a flavonoid plant dye solution, stir thoroughly, let stand for aging, filter, separate and dry after the reaction to obtain the interlayer confined hybrid complex. (2) The interlayer confinement hybrid complex is activated with a surface activator to obtain a surface-activated interlayer confinement hybrid complex; (3) The surface-activated interlayer confined hybrid complex is added to the hindered phenolic antioxidant solution, stirred thoroughly, filtered, and vacuum dried to obtain confined flavonoid plant dyes; the vacuum drying is carried out at 50~60℃ for 10~12 hours, and then heated to 120~150℃ for 2~4 hours.

2. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, In metal ion modified montmorillonite, the metal ions are selected from Al 3+ Mg 2+ Zn 2+ One of them.

3. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, Flavonoid dyes are selected from one or more of the following plant dyes: Sophora japonica flower dye, Scutellaria baicalensis flower dye, Cotinus coggygria flower dye, and mulberry leaf dye.

4. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, In step (1), the mass ratio of flavonoid plant dyes to metal ion-modified montmorillonite is 1:3 to 1:

5.

5. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, In step (1), the stirring conditions are: stirring reaction at 60~80℃ for 4~8 h; and standing aging time is 12~14 h.

6. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, The specific method of step (2) is as follows: the interlayer confinement hybrid complex is dispersed in an ethanol mixed solvent, 1~3 wt% of surfactant is added to the interlayer confinement hybrid complex, and the mixture is stirred at 50℃~80℃ for 3 h~6 h. After washing and drying, the surface-activated interlayer confinement hybrid complex is obtained.

7. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, The surfactant is a silane coupling agent selected from at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

8. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, In step (3), the amount of hindered phenolic antioxidant added is 1% to 10% of the mass of the surface-activated interlayer confined hybrid complex.

9. The method for preparing confined heat-resistant flavonoid plant dyes according to claim 1, characterized in that, In step (3), the stirring temperature is 40~60℃ and the time is 1~3 h.

10. A confined heat-resistant flavonoid plant dye prepared by the preparation method according to any one of claims 1-9.

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