Nanocapsule organosilicon coated starch and method for its preparation

Abstract

The application belongs to the technical field of industrial starch, and particularly relates to a kind of nano microcapsule organic silicon coating starch, which is made of the following components by weight: composite modified starch 50-100 parts, and vinyl acetate microemulsion 50-80 parts; wherein, the preparation components of the composite modified starch are: corn starch 80-100 parts, water 40-60 parts, oxidizing agent 2-5 parts, reducing agent 2-5 parts, lye 20-40 parts, succinic anhydride 10-20 parts, methyl silicic acid 5-10 parts, and silane coupling agent 2-5 parts. The application adopts oxidation-reduction, composite esterification, dispersion emulsification polymerization and other processes. The introduction of carboxylic acid groups on the succinyl group in the composite esterification reaction greatly enhances the hydrophilicity of the starch. Meanwhile, the introduction of organic silicon groups improves the temperature resistance of the modified starch.

Description

Technical Field

[0001] This invention belongs to the field of industrial starch technology, specifically relating to a nano-microcapsule organosilicon-coated starch and its preparation method. Background Technology

[0002] Surface sizing involves applying sizing liquid to the surface of paper or paperboard using a sizing machine or by immersing the paper in a sizing agent solution to form a layer of sizing particles. After the sizing agent dries, a liquid-resistant film forms on the paper surface, giving the paper or paperboard a certain surface strength while also providing good water resistance. After surface sizing, a water-resistant film forms on the paper surface, which not only enhances the surface strength of the paper but also improves its water resistance, printability, abrasion resistance, and durability, thus reducing paper linting and dusting during printing. Traditional in-pulp sizing results in significant loss during papermaking, easily leading to increased white water load, paper machine contamination, and decreased paper strength. Currently, the papermaking industry is gradually shifting from in-pulp sizing to surface sizing.

[0003] Natural starch, due to its abundant resources, low cost, and renewable and biodegradable properties, is currently the most widely used surface sizing agent in my country. However, with the rapid development of the modern papermaking industry and the continuous adoption of new processes, equipment, and technologies, the requirements for modified starch used in paper coating and sizing are becoming increasingly stringent. Single-modified starches are insufficient to fully meet these needs. As a result, modified and composite modified starches have emerged, and their application in the papermaking industry has been affirmed.

[0004] Currently, there are many types of surface sizing agents on the market, each with different functions and purposes. They are mainly used to improve the strength of paper or paperboard or enhance printing performance. However, the main function and purpose of surface sizing agents for grey-coated white cardboard is to resist the diffusion and penetration of liquids. The quality of surface sizing agents is closely related to the processing technology and the molecular weight of the polymer. Currently, there are two main categories of surface sizing agents on the market: one category consists of natural products represented by starch, PVA, and CMC; the other category consists of synthetic products represented by styrene-maleic anhydride copolymers, styrene-acrylic acid copolymers, AKD polymers, and polyurethane dispersions. Starch is an important renewable and biodegradable natural resource. Starch molecules have many hydroxyl groups, which can absorb water and swell under certain temperature conditions, resulting in gelatinization and a certain degree of viscosity and adhesion. It has wide applications in industry, and many modified varieties exist. However, its adhesion, water retention, especially its water solubility and resistance to surface diffusion and penetration of liquids, have certain limitations, which restrict its application. To address these shortcomings, methods such as wet oxidative modification of oxidized starch result in unsatisfactory water retention, flowability, and adhesion. Acetate starch, through wet esterification and oxidative modification, introduces non-ionic acetyl groups that are easily hydrolyzed and detached under alkaline conditions, leading to unstable flowability and water retention. Phosphate starch, modified through dry phosphate esterification, introduces anionic phosphate groups, which form anionic waste during paper recycling, negatively impacting the wet end of the paper machine. Existing technology discloses a modified starch, TB-201, a composite modified starch obtained through two chemical modifications. By introducing various active groups into the starch molecule, its gelatinization temperature, rheology, stability, film-forming properties, and adhesion are significantly improved, making it an excellent new material suitable for coating and sizing in modern papermaking. However, the preparation process of this modified starch uses large amounts of strong alkalis and other chemicals, causing significant environmental damage. Another technology utilizes twin-screw extrusion to produce nano-starch for paper coating. This process is simple, generates no wastewater, has high reaction efficiency, and low production costs. The extrusion method for producing coating nano-starch not only plasticizes the starch to enhance its adhesive strength but also gelatinizes it. By adding a cross-linking agent in the later stages of extrusion, the precipitated starch molecules undergo dry cross-linking, forming stable nano-sized starch. This nano-starch is characterized by high solids content, low viscosity, good flowability, strong adhesion, and ease of use. It can replace 30-60% of styrene-butadiene latex, improving paper performance, reducing costs, and being environmentally friendly. While the above technologies have solved the challenges of starch stability, water retention, flowability, and adhesive strength, their temperature resistance and ability to resist surface diffusion and penetration of liquids still have shortcomings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nano-microcapsule organosilicon-coated starch with good heat resistance, excellent surface diffusion and penetration ability, and high surface strength for sizing on paper.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 50 to 100 parts of composite modified starch and 50 to 80 parts of vinyl acetate microemulsion.

[0008] The components for preparing the composite modified starch are: 80-100 parts corn starch, 40-60 parts water, 2-5 parts oxidant, 2-5 parts reducing agent, 20-40 parts alkali solution, 10-20 parts succinic anhydride, 5-10 parts methylsilicic acid, and 2-5 parts silane coupling agent.

[0009] In a preferred example, the corn starch has a particle size of 30 nm to 100 nm, an ash content of less than 0.5%, and a pH of 6.0 to 7.0.

[0010] In a preferred example, the oxidant is hydrogen peroxide or sodium hypochlorite.

[0011] In a preferred example, the reducing agent is ferrous sulfate or sodium metabisulfite.

[0012] In a preferred example, the alkaline solution is a NaOH solution or a KOH solution, wherein the mass fraction of the NaOH solution is 5% to 10% and the mass fraction of the KOH solution is 5% to 10%.

[0013] In a preferred embodiment, the silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, and tetraethyl orthosilicate.

[0014] In a preferred embodiment, the preparation process of the vinyl acetate microemulsion is as follows: while stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added and stirred rapidly to form a microemulsion. Then, under a nitrogen atmosphere, the temperature is slowly raised to the decomposition temperature of the initiation system, and then an initiator is added. The reaction is carried out for 30 min to 60 min to obtain a vinyl acetate microemulsion with a particle size distribution of 20 nm to 30 nm and a Zeta potential of -23.0 mV to -25.0 mV.

[0015] The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10, and SDS is 200–220: 25–35: 8–12: 0.1–0.3.

[0016] In a preferred embodiment, the volume ratio of the deionized water, vinyl acetate, butyl acrylate, OP-10, and SDS is 180:30:10:0.2.

[0017] Based on a general inventive concept, another object of the present invention is to provide a method for preparing organosilicon-coated starch nanocapsules, comprising the following steps:

[0018] (1) First, corn starch and water are mixed to make starch milk, then an oxidant is added to carry out an oxidation reaction. After the oxidation reaction is completed, a reducing agent is added to carry out a reduction reaction. After the reduction reaction is completed, an alkaline solution is added to adjust the pH of the solution to 6.0-7.0. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.1 ml / s-0.5 ml / s to carry out a composite esterification reaction. The reaction is carried out at 60℃-80℃ for 1-2 hours. Then, a silane coupling agent is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, the composite modified starch is obtained.

[0019] (2) First, mix vinyl acetate microemulsion and composite modified starch evenly, then polymerize the emulsion at 75℃~85℃ for 1h~2h, then add wall material, disperse quickly, and obtain nano-microcapsule organosilicon coated starch after separation and drying.

[0020] In a preferred example, the wall material is chitosan or cellulose.

[0021] Compared with the prior art, the present invention adopts the above-mentioned oxidation-reduction, composite esterification, dispersion emulsification polymerization and other processes. The introduction of carboxylic acid groups on the succinyl group in the composite esterification reaction greatly enhances the hydrophilicity of starch. At the same time, the introduction of organosilicon groups improves the temperature resistance of modified starch. In contrast, the molecules of single oxidized coated starch, oxidative acetylated starch and oxidative phosphorylated starch do not have the above-mentioned groups.

[0022] The advantages of the organosilicon-coated starch nanocapsule product prepared by this invention are as follows:

[0023] (1) It has good paste transparency and film-forming properties. When applied to the sizing of paper surfaces, it can make the paper have excellent smoothness performance and greatly improve the paper's printability. It does not shed powder or lint.

[0024] (2) It has very high water retention, reduced sedimentation, high stability, and good compatibility with other coatings; and because succinic anhydride has a certain cross-linking effect on starch, it greatly enhances the starch's tolerance to the environment and greatly strengthens its strength, which has an excellent effect on enhancing the surface strength of coated paper.

[0025] (3) Introducing organosilicon groups as low surface energy materials has good surface diffusion and penetration capabilities, which is beneficial to improving its temperature resistance and compatibility with paper, and reducing environmental harm. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described in conjunction with specific embodiments. However, this invention is not limited to these embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. In this invention, unless otherwise specified, all parts and percentages are units of mass, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0027] The terms “comprising,” “including,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0028] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0029] Example 1

[0030] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 75 parts of composite modified starch and 65 parts of vinyl acetate microemulsion.

[0031] The components for preparing the composite modified starch are: 90 parts corn starch, 50 parts water, 3.5 parts hydrogen peroxide, 3.5 parts ferrous sulfate, 30 parts 8%wt NaOH solution, 15 parts succinic anhydride, 7.5 parts methylsilicic acid, and 3.5 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0032] The corn starch has an average particle size of 65 nm, an ash content of 0.3%, and a pH of 6.5.

[0033] The preparation process of the vinyl acetate microemulsion is as follows: under the condition of stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added and stirred rapidly to form a microemulsion. Then, under a nitrogen atmosphere, the temperature is slowly raised to the decomposition temperature of the initiation system, and then an initiator is added. The reaction is carried out for 45 minutes to obtain a vinyl acetate microemulsion with an average particle size of 25 nm and an average zeta potential of -24.1 mV. The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10 and SDS is 180:30:10:0.2.

[0034] The preparation method of the above-mentioned organosilicon-coated starch nanocapsules includes the following steps:

[0035] (1) First, corn starch and water are mixed to make starch milk, then hydrogen peroxide is added to carry out oxidation reaction. After the oxidation reaction is completed, ferrous sulfate is added to carry out reduction reaction. After the reduction reaction is completed, 8% wt NaOH solution is added to adjust the pH of the solution to 6.5. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.3 ml / s to carry out composite esterification reaction. The reaction is carried out at 70℃ for 1.5 h. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, composite modified starch is obtained.

[0036] (2) First, the vinyl acetate microemulsion and the composite modified starch are mixed evenly, and then the emulsion is polymerized at 80°C for 1.5h. Then, chitosan is added and dispersed quickly. After separation and drying, the nano-microcapsule organosilicon-coated starch is obtained.

[0037] In this embodiment, the heat resistance of the organosilicon-coated starch nanocapsules is 162℃, and the surface diffusion and penetration capacity is 81kN / m.

[0038] Example 2

[0039] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 100 parts of composite modified starch and 50 parts of vinyl acetate microemulsion.

[0040] The components for preparing the composite modified starch are: 100 parts corn starch, 40 parts water, 5 parts sodium hypochlorite, 2 parts sodium metabisulfite, 40 parts 6%wt KOH solution, 10 parts succinic anhydride, 10 parts methylsilicic acid, and 2 parts γ-aminopropyltriethoxysilane.

[0041] The corn starch has an average particle size of 100 nm, an ash content of 0.3%, and a pH of 6.1.

[0042] The preparation process of the vinyl acetate microemulsion is as follows: under the condition of stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added and stirred rapidly to form a microemulsion. Then, under a nitrogen atmosphere, the temperature is slowly raised to the decomposition temperature of the initiation system, and then an initiator is added. The reaction is carried out for 60 minutes to obtain a vinyl acetate microemulsion with an average particle size distribution of 27 nm and an average zeta potential of -24.6 mV. The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10 and SDS is 220:25:12:0.1.

[0043] The preparation method of the above-mentioned organosilicon-coated starch nanocapsules includes the following steps:

[0044] (1) First, corn starch and water are mixed to make starch milk, and then sodium hypochlorite is added for oxidation reaction. After the oxidation reaction is completed, sodium metabisulfite is added for reduction reaction. After the reduction reaction is completed, 6% wt KOH solution is added to adjust the pH of the solution to 6.8. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.5 ml / s for composite esterification reaction. The reaction is carried out at 60℃ for 2 h. Then, γ-aminopropyltriethoxysilane is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, composite modified starch is obtained.

[0045] (2) First, the vinyl acetate microemulsion and the composite modified starch are mixed evenly, and then the emulsion is polymerized at 85°C for 1 hour. Then, cellulose is added and dispersed quickly. After separation and drying, the nano-microcapsule organosilicon coated starch is obtained.

[0046] In this embodiment, the heat resistance of the organosilicon-coated starch nanocapsules is 158℃, and the surface diffusion and penetration capacity is 79kN / m.

[0047] Example 3

[0048] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 50 parts of composite modified starch and 80 parts of vinyl acetate microemulsion.

[0049] The components for preparing the composite modified starch are: 80 parts corn starch, 60 parts water, 2 parts hydrogen peroxide, 5 parts sodium metabisulfite, 20 parts 7%wt NaOH solution, 20 parts succinic anhydride, 5 parts methylsilicic acid, and 5 parts tetraethyl orthosilicate.

[0050] The corn starch has an average particle size of 30 nm, an ash content of 0.2%, and a pH of 6.8.

[0051] The preparation process of the vinyl acetate microemulsion is as follows: under the condition of stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added and stirred rapidly to form a microemulsion. Then, under a nitrogen atmosphere, the temperature is slowly raised to the decomposition temperature of the initiation system, and then an initiator is added. The reaction is carried out for 30 minutes to obtain a vinyl acetate microemulsion with an average particle size of 24 nm and an average zeta potential of -23.8 mV. The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10 and SDS is 200:35:8:0.3.

[0052] The preparation method of the above-mentioned organosilicon-coated starch nanocapsules includes the following steps:

[0053] (1) First, corn starch and water are mixed to make starch milk, then hydrogen peroxide is added to carry out oxidation reaction. After the oxidation reaction is completed, sodium metabisulfite is added to carry out reduction reaction. After the reduction reaction is completed, 7% wt NaOH solution is added to adjust the pH of the solution to 6.2. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.1 ml / s to carry out composite esterification reaction. The reaction is carried out at 80℃ for 1 h. Then, tetraethyl orthosilicate is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, composite modified starch is obtained.

[0054] (2) First, the vinyl acetate microemulsion and the composite modified starch are mixed evenly, and then the emulsion is polymerized at 75°C for 2 hours. Then, chitosan is added and dispersed quickly. After separation and drying, the nano-microcapsule organosilicon-coated starch is obtained.

[0055] In this embodiment, the heat resistance of the organosilicon-coated starch nanocapsules is 155℃, and the surface diffusion and penetration capacity is 78kN / m.

[0056] Example 4

[0057] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 100 parts of composite modified starch and 80 parts of vinyl acetate microemulsion.

[0058] The components for preparing the composite modified starch are: 100 parts corn starch, 60 parts water, 5 parts hydrogen peroxide, 5 parts sodium metabisulfite, 40 parts 10%wt KOH solution, 20 parts succinic anhydride, 10 parts methylsilicic acid, and 5 parts γ-aminopropyltriethoxysilane.

[0059] The corn starch has an average particle size of 100 nm, an ash content of 0.4%, and a pH of 7.0.

[0060] The preparation process of the vinyl acetate microemulsion is as follows: under the condition of stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added and stirred rapidly to form a microemulsion. Then, under a nitrogen atmosphere, the temperature is slowly raised to the decomposition temperature of the initiation system, and then an initiator is added. The reaction is carried out for 60 min to obtain a vinyl acetate microemulsion with an average particle size of 20 nm to 30 nm and an average zeta potential of -23.0 mV to -25.0 mV. The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10 and SDS is 220:35:12:0.3.

[0061] The preparation method of the above-mentioned organosilicon-coated starch nanocapsules includes the following steps:

[0062] (1) First, corn starch and water are mixed to make starch milk, then an oxidant is added to carry out an oxidation reaction. After the oxidation reaction is completed, a reducing agent is added to carry out a reduction reaction. After the reduction reaction is completed, an alkaline solution is added to adjust the pH of the solution to 7.0. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.5 ml / s to carry out a composite esterification reaction. The reaction is carried out at 80℃ for 2 hours. Then, a silane coupling agent is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, the composite modified starch is obtained.

[0063] (2) First, the vinyl acetate microemulsion and the composite modified starch are mixed evenly, and then the emulsion is polymerized at 85°C for 2 hours. Then, chitosan is added and dispersed quickly. After separation and drying, the nano-microcapsule organosilicon-coated starch is obtained.

[0064] In this embodiment, the heat resistance of the organosilicon-coated starch nanocapsules is 160℃, and the surface diffusion and penetration capacity is 78kN / m.

[0065] Example 5

[0066] A nano-microcapsule organosilicon-coated starch is made from the following components in parts by weight: 50 parts of composite modified starch and 50 parts of vinyl acetate microemulsion.

[0067] The components for preparing the composite modified starch are: 80 parts corn starch, 40 parts water, 2 parts sodium hypochlorite, 2 parts sodium metabisulfite, 20 parts 5%wt KOH solution, 10 parts succinic anhydride, 5 parts methylsilicic acid, and 2 parts tetraethyl orthosilicate.

[0068] The corn starch has an average particle size of 30 nm, an ash content of 0.1%, and a pH of 6.0.

[0069] The preparation process of the vinyl acetate microemulsion is as follows: While stirring and mixing deionized water, vinyl acetate, and butyl acrylate, OP-10 and SDS are added and rapidly stirred to form a microemulsion. The mixture is then slowly heated to the decomposition temperature of the initiation system under a nitrogen atmosphere. An initiator is then added, and the reaction is allowed to proceed for 30 minutes to obtain a vinyl acetate microemulsion with a particle size distribution of 20 nm to 30 nm and a Zeta potential of -23.0 mV to -25.0 mV. The volume ratio of deionized water, vinyl acetate, butyl acrylate, OP-10, and SDS is 200:25:8:0.1.

[0070] The preparation method of the above-mentioned organosilicon-coated starch nanocapsules includes the following steps:

[0071] (1) First, corn starch and water are mixed to make starch milk, then an oxidant is added to carry out an oxidation reaction. After the oxidation reaction is completed, a reducing agent is added to carry out a reduction reaction. After the reduction reaction is completed, an alkaline solution is added to adjust the pH of the solution to 6.0. Then, succinic anhydride and methylsilicic acid are slowly added at a dropping rate of 0.1 ml / s to carry out a composite esterification reaction. The reaction is carried out at 60°C for 1 h. Then, a silane coupling agent is added. At the same time, the reaction solution is treated with ultrasound. Finally, after centrifugation and washing, the composite modified starch is obtained.

[0072] (2) First, the vinyl acetate microemulsion and the composite modified starch are mixed evenly, and then the emulsion is polymerized at 75°C for 1 hour. Then, cellulose is added and dispersed quickly. After separation and drying, the nano-microcapsule organosilicon coated starch is obtained.

[0073] In this embodiment, the heat resistance of the organosilicon-coated starch nanocapsules is 152℃, and the surface diffusion and penetration capacity is 76kN / m.

[0074] Comparative Example 1

[0075] It does not contain the component succinic anhydride, and is otherwise the same as in Example 1.

[0076] The heat resistance of the coated starch in this comparative example is 152℃, and its surface diffusion and penetration capacity is 51kN / m.

[0077] Comparative Example 2

[0078] It does not contain the component γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and is otherwise the same as in Example 1.

[0079] The heat resistance of the coated starch in this comparative example is 108℃, and its surface diffusion and penetration capacity is 76kN / m.

[0080] The organosilicon-coated starch nanocapsules prepared in Examples 1-5 and Comparative Examples 1-2 were used for surface sizing on paper that had not undergone surface sizing. The sizing amount was controlled at 2 ± 0.1 g / m². 2 The paper properties were tested at 60℃, and the results are shown in Table 1 below:

[0081] Table 1. Test results of sized paper properties

[0082]

[0083] The experimental data above show that the organosilicon-coated starch nanocapsules in this invention have good heat resistance, excellent surface diffusion and penetration capabilities, and high surface strength.

[0084] The above embodiments are merely preferred embodiments of the present invention. Any simple modifications, alterations, and substitutions made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A nanocapsule organosilicon-coated starch, characterized in that, The composite modified starch is made from the following components by weight: 50-100 parts of composite modified starch, 50-80 parts of vinyl acetate microemulsion; The preparation components of the composite modified starch are: 80-100 parts of corn starch, 40-60 parts of water, 2-5 parts of oxidizing agent, 2-5 parts of reducing agent, 20-40 parts of lye, 10-20 parts of succinic anhydride, 5-10 parts of methyl silicic acid, and 2-5 parts of silane coupling agent; The preparation process of the vinyl acetate microemulsion is: under the condition of stirring and mixing deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS are added to form a microemulsion, then the temperature is slowly raised to the decomposition temperature of the initiator system under a nitrogen atmosphere, and then the initiator is added, and the reaction is carried out for 30-60 min to obtain a vinyl acetate microemulsion with a particle size distribution of 20-30 nm and a Zeta potential of-23.0 mv to-25.0 mv; The volume ratio of the deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS is 200-220:25-35:8-12:0.1-0.

3. The preparation method of the nano-microcapsule organosilicon coated starch comprises the following steps: (1) first, corn starch and water are mixed to form a starch emulsion, then an oxidizing agent is added for oxidation reaction, after the oxidation reaction is completed, a reducing agent is added for reduction reaction, after the reduction reaction is completed, lye is added to adjust the pH of the solution to 6.0-7.0, then succinic anhydride and methyl silicic acid are slowly added at a dropping speed of 0.1-0.5 ml / s for composite esterification reaction, the reaction is carried out at 60-80℃ for 1-2 h, then a silane coupling agent is added, and the reaction solution is treated with ultrasonic waves, and finally the composite modified starch is obtained through centrifugal separation and washing; (2) first, the vinyl acetate microemulsion and the composite modified starch are mixed uniformly, then emulsion polymerization is carried out at 75-85℃ for 1-2 h, then the wall material is added and quickly dispersed, and the nano-microcapsule organosilicon coated starch is obtained after separation and drying.

2. A nanocapsulated organosilicon coated starch according to claim 1, characterized in that, The particle size of the corn starch is 30-100 nm, the ash content is less than 0.5%, and the pH is 6.0-7.

0.

3. The nanocapsulated organosilicon coated starch of claim 1, wherein, The oxidizing agent is hydrogen peroxide or sodium hypochlorite.

4. The nanocapsulated organosilicon coated starch of claim 1, wherein, The reducing agent is ferrous sulfate or sodium metabisulfite.

5. The nanocapsulated organosilicon coated starch of claim 1, wherein, The lye is NaOH solution or KOH solution, the mass fraction of the NaOH solution is 5-10%, and the mass fraction of the KOH solution is 5-10%.

6. The nanocapsulated organosilicon coated starch of claim 1, wherein, The silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy) propyl trimethoxysilane, γ-aminopropyl triethoxysilane and tetraethyl orthosilicate.

7. The nanocapsulated organosilicon coated starch of claim 1, wherein, The volume ratio of the deionized water, vinyl acetate and butyl acrylate, OP-10 and SDS is 180:30:10:0.

2.

8. Process for the preparation of nanocapsulated organosilicon coated starch according to any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: (1) first corn starch and water into starch milk, then add oxidizing agent for oxidation reaction, after oxidation reaction, add reducing agent for reduction reaction, after reduction reaction, then add lye to adjust the pH of the solution to 6.0-7.0, then slowly add succinic anhydride and methyl silicic acid with a dropwise addition rate of 0.1ml / s-0.5ml / s, and then perform a complex esterification reaction at 60-80℃ for 1-2h, then add a silane coupling agent while treating the reaction solution with ultrasonic waves, and finally obtain a complex modified starch after centrifugal separation and washing; (2) first mix the vinyl acetate microemulsion and the complex modified starch uniformly, then perform emulsion polymerization at 75-85℃ for 1-2h, then add a wall material, quickly disperse, and then obtain a nano microcapsule organosilicon coated starch after separation and drying.

9. A process for the preparation of nanocapsule organosilicon coated starch according to claim 8, characterized in that, The wall material is chitosan or cellulose.

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