High-strength water-based barrier coating and its application in environmentally friendly food paper

Abstract

The application discloses a kind of high-strength water-based barrier coating and its application in environmental protection food paper material, belong to environmental protection easy degradation packaging technical field, by adding hydrophobic and oleophobic core-shell filler to high-strength water-based barrier coating, the filler is with epoxy group terminated phenyl POSS as rigid inorganic core layer, hyperbranched polysiloxane is as flexible organic shell layer, by ring-opening addition reaction of epoxy group and amino group Covalent bond grafting can give high-strength water-based barrier coating good hydrophobic and oleophobic dirt characteristics, avoid food packaging to be contaminated by oil dirt, prolong the service life of food packaging;The existence of epoxy group in the application can be used as hyperbranched polysiloxane nucleation site, to make hyperbranched polysiloxane coat epoxy group terminated phenyl POSS, the coating of hyperbranched polysiloxane retains the three-dimensional porous structure of epoxy group terminated phenyl POSS, improves the strength of coating, also avoids the reduction of barrier property caused by porous structure.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly and biodegradable packaging technology, specifically a high-strength water-based barrier coating and its application in environmentally friendly food paper materials. Background Technology

[0002] With the rapid development of the food industry and consumers' increasing demands for food safety and quality, the functional requirements of food packaging materials are becoming increasingly prominent. Traditional food packaging materials often only possess basic barrier properties, which are insufficient to meet the needs of modern food preservation.

[0003] Acrylic polymers are used in barrier coatings for paper-based materials because they have good water vapor and oil barrier properties after film formation, as well as good adhesion to paper materials. However, acrylic polymers have shortcomings in mechanical properties, mainly in their insufficient toughness and tensile strength. When paper-based materials are folded, cracks are easily generated at the folding position due to stretching, which leads to the failure of barrier properties.

[0004] Chinese patent application CN119434019A discloses a barrier coating composition, barrier coating and paper substrate for paper-based materials. The main component of the formulation is a strong hydrophilic component, with only a small amount of hydrophobic polysiloxane grafted acrylic monomer. It is prone to oil stains in mainstream foods such as bread, cakes, fried foods, cooked foods and sauces, which makes the outer packaging of food easily soaked in oil and wrinkled, affecting the long service life of the outer packaging. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength water-based barrier coating and its application in environmentally friendly food paper materials. By adding a hydrophobic and oleophobic core-shell filler to the high-strength water-based barrier coating, the filler uses epoxy-terminated phenyl POSS as a rigid inorganic core layer and hyperbranched polysiloxane as a flexible organic shell layer. Covalent grafting is achieved through the ring-opening addition reaction of epoxy groups and amino groups. The core-shell structure is uniform and stable, which can endow the high-strength water-based barrier coating with good hydrophobic and oleophobic properties, avoid food packaging from being contaminated by oil, and extend the service life of food packaging.

[0006] The objective of this invention can be achieved through the following technical solutions: A high-strength water-based barrier coating is prepared by the following steps: Acrylic emulsion, chitosan, bentonite, microcrystalline cellulose, waterborne polyurethane, hydrophobic and oleophobic core-shell filler, glycidyl methacrylate, carboxymethyl cellulose, defoamer, leveling agent and deionized water are mixed to form a high-strength waterborne barrier coating. This coating is then applied to the surface of food-grade white cardboard and dried and cured to obtain a high-strength waterborne barrier coating layer.

[0007] Furthermore, the ratio of acrylic emulsion, chitosan, bentonite, microcrystalline cellulose, waterborne polyurethane, hydrophobic and oleophobic core-shell filler, glycidyl methacrylate, carboxymethyl cellulose, defoamer, leveling agent, and deionized water is 23-25:12-14:18-20:10-12:7-9:4-6:1-1.5:2-4:0.5-1:0.5-1:17-19.

[0008] Furthermore, the specific preparation steps for the hydrophobic and oleophobic core-shell packing are as follows: Epoxy-terminated phenyl POSS and tetrahydrofuran were added to a reaction vessel and stirred for 20-30 min at 20-25℃ and 500-600 r / min. Then, hyperbranched polysiloxane and anhydrous ethanol were added, and the mixture was heated to 60-70℃ and reacted for 12-14 h. The mixture was then filtered, and the product was washed 2-4 times with tetrahydrofuran, anhydrous ethanol and deionized water. The product was then vacuum dried at 60-70℃ for 1-2 h to obtain a hydrophobic and oleophobic core-shell packing.

[0009] Furthermore, the ratio of epoxy-terminated phenyl POSS, tetrahydrofuran, hyperbranched polysiloxane, and anhydrous ethanol is 10-12g: 200-300mL: 6.72-7.2g: 20-30mL.

[0010] Furthermore, epoxy-terminated phenyl POSS is obtained by the silanol condensation reaction of oligomeric phenyl POSS intermediate with γ-glycidoxypropyltrimethoxysilane under the action of a catalyst and then purification.

[0011] The mass ratio of oligomeric phenyl POSS intermediate, γ-glycidyl etheroxypropyltrimethoxysilane and catalyst is (5-6):(1-2):(0.8-1.1).

[0012] The catalyst was prepared by mixing formic acid, tetrabutylammonium fluoride and tetramethylammonium hydroxide in a mass ratio of (4-6):(1.5-2):(2.5-3).

[0013] The specific preparation steps for epoxy-terminated phenyl POSS are as follows: Oligophenyl POSS intermediate, tetrahydrofuran, γ-glycidyl etheroxypropyltrimethoxysilane, formic acid, tetrabutylammonium fluoride, tetramethylammonium hydroxide and deionized water were added to a reaction vessel and stirred for 80-90 h at 20-25 °C and 500-600 r / min. Then calcium chloride was added and stirred for 24-26 h to adsorb impurities. After filtration, the solvent was removed by rotary evaporation of the filtrate, and the precipitate was placed in ice-cold methanol. After recrystallization, the precipitate was filtered and the filter cake was vacuum dried at 60-70 °C for 1-2 h to obtain epoxy-terminated phenyl POSS.

[0014] Furthermore, the specific preparation steps for the oligophenyl POSS intermediate are as follows: Phenylacetyltriethoxysilane, a 1 mol / L tetrabutylammonium fluoride solution, deionized water, and anhydrous ethanol were added to a reaction vessel and stirred at 20-25℃ and 500-600 r / min for 80-90 h to form a colorless and transparent solution. Stirring was continued until a white precipitate was formed. After the reaction was completed, the mixture was filtered, and the product was washed 2-4 times with deionized water and dried under vacuum at 60-70℃ for 1-2 h to obtain the oligomeric phenyl POSS intermediate.

[0015] Furthermore, the ratio of phenyltriethoxysilane, tetrabutylammonium fluoride solution, deionized water and anhydrous ethanol is 10-12g: 2-4mL: 8-10mL: 45-50mL.

[0016] Furthermore, the specific preparation steps for hyperbranched polysiloxanes are as follows: 3-Aminopropyltriethoxysilane and ethanol were added to a reaction vessel and stirred for 20-30 min at 20-25 °C and 500-600 r / min. Nitrogen gas was introduced to remove oxygen, then deionized water was added and the mixture was heated to 60-70 °C and reacted for 4-6 h. Ethanol and deionized water were removed by rotary evaporation, and the mixture was dried under vacuum at 60-70 °C for 1-2 h to obtain hyperbranched polysiloxane.

[0017] Furthermore, the ratio of 3-aminopropyltriethoxysilane, ethanol, and deionized water is 44-46 g: 40-50 mL: 4-5 mL.

[0018] This invention also provides the application of a high-strength water-based barrier coating in environmentally friendly food paper materials.

[0019] The beneficial effects of this invention are: 1. The high-strength waterborne barrier coating prepared by this invention contains a hydrophobic and oleophobic core-shell filler. This hydrophobic and oleophobic core-shell filler uses epoxy-terminated phenyl POSS as a rigid inorganic core layer and hyperbranched polysiloxane as a flexible organic shell layer. Covalent grafting is achieved through the ring-opening addition reaction of epoxy groups and amino groups. The core-shell structure is uniform and stable, which can endow the high-strength waterborne barrier coating with good hydrophobic and oleophobic properties, avoid food packaging from being contaminated by oil, and extend the service life of food packaging.

[0020] 2. The epoxy-terminated phenyl POSS prepared in this invention is a core layer containing both rigid side phenyl groups and epoxy groups. The presence of epoxy groups can serve as nucleation sites for hyperbranched polysiloxanes, promoting the hyperbranched polysiloxanes to encapsulate the epoxy-terminated phenyl POSS. The encapsulation by hyperbranched polysiloxanes not only preserves the three-dimensional porous structure of the epoxy-terminated phenyl POSS and improves the strength of the coating, but also avoids the reduction in barrier properties caused by the porous structure.

[0021] 3. In this invention, the presence of phenyl groups creates steric hindrance on the surface of epoxy-terminated phenyl POSS, effectively preventing excessive condensation and aggregation between POSS molecules, ensuring effective coating of hyperbranched polysiloxane. Furthermore, phenyl groups exhibit strong repulsion of polar water molecules, demonstrating excellent hydrophobic properties. However, due to the high surface energy of phenyl groups, their ability to repel non-polar oils is limited. Hyperbranched polysiloxane, with Si-O-Si as its main chain, has ultra-low surface energy, which can strongly repel non-polar food oil stains and construct a dense barrier layer, achieving highly efficient oleophobic properties. The two are covalently bonded to form a core-shell structure. The rigid core of POSS provides hydrophobicity and structural stability, while the flexible shell of hyperbranched polysiloxane endows the material with oleophobic functionality, synergistically achieving the dual hydrophobic and oleophobic properties of the coating. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A high-strength water-based barrier coating, prepared by the following steps: S1: 10g of phenyltriethoxysilane, 2mL of 1mol / L tetrabutylammonium fluoride solution, 8mL of deionized water and 45mL of anhydrous ethanol were added to a reaction vessel and stirred at 20℃ and 500r / min for 80h to form a colorless and transparent solution. Stirring was continued until a white precipitate was formed. After the reaction was completed, the product was filtered, washed twice with deionized water, and dried under vacuum at 60℃ for 1h to obtain oligomeric phenyl POSS intermediate.

[0024] S2: 5g of oligophenyl POSS intermediate, 70mL of tetrahydrofuran, 1g of γ-glycidyl etheroxypropyltrimethoxysilane, 0.4g of formic acid, 0.15g of tetrabutylammonium fluoride, 0.25g of tetramethylammonium hydroxide and 4mL of deionized water were added to a reaction vessel and stirred at 20℃ and 500r / min for 80h. Then, 1g of calcium chloride was added and stirred for 24h to adsorb impurities. After filtration, the filtrate was evaporated by rotary evaporation to remove the solvent, placed in ice-cold methanol to precipitate, recrystallized, filtered, and the filter cake was vacuum dried at 60℃ for 1h to obtain epoxy-terminated phenyl POSS.

[0025] S3: Add 44g of 3-aminopropyltriethoxysilane and 40mL of ethanol to a reaction vessel, stir for 20min at 20℃ and 500r / min, purge with nitrogen to remove oxygen, add 4mL of deionized water, heat to 60℃, continue the reaction for 4h, remove ethanol and deionized water by rotary evaporation, and vacuum dry at 60℃ for 1h to obtain hyperbranched polysiloxane.

[0026] S4: 10g of epoxy-terminated phenyl POSS and 200mL of tetrahydrofuran were added to the reactor and stirred for 20min at 20℃ and 500r / min. Then, 6.72g of hyperbranched polysiloxane and 20mL of anhydrous ethanol were added, and the mixture was heated to 60℃ and reacted for 12h. The mixture was then filtered, and the product was washed twice with tetrahydrofuran, anhydrous ethanol and deionized water. The product was then dried under vacuum at 60℃ for 1h to obtain a hydrophobic and oleophobic core-shell packing.

[0027] S5: Mix 23g acrylic emulsion, 12g chitosan, 18g bentonite, 10g microcrystalline cellulose, 7g waterborne polyurethane, 4g hydrophobic and oleophobic core-shell filler, 1g glycidyl methacrylate, 2g carboxymethyl cellulose, 0.5g defoamer BYK-024, 0.5g leveling agent BYK-348, and 17g deionized water to form a high-strength waterborne barrier coating with a viscosity of 200mPa·s. Apply the high-strength waterborne barrier coating evenly to the surface of food-grade white cardboard by spraying. Dry and cure under vacuum at 60℃ for 15min to obtain a high-strength waterborne barrier coating with a thickness of 10μm.

[0028] Example 2: A high-strength water-based barrier coating, prepared by the following steps: S1: 11g of phenyltriethoxysilane, 3mL of 1mol / L tetrabutylammonium fluoride solution, 9mL of deionized water and 47.5mL of anhydrous ethanol were added to a reaction vessel and stirred at 22.5℃ and 550r / min for 85h to form a colorless and transparent solution. Stirring was continued until a white precipitate was formed. After the reaction was completed, the product was filtered, washed three times with deionized water, and dried under vacuum at 65℃ for 1.5h to obtain oligomeric phenyl POSS intermediate.

[0029] S2: 5.5 g of oligophenyl POSS intermediate, 75 mL of tetrahydrofuran, 1.5 g of γ-glycidyl etheroxypropyltrimethoxysilane, 0.5 g of formic acid, 0.175 g of tetrabutylammonium fluoride, 0.275 g of tetramethylammonium hydroxide and 5 mL of deionized water were added to a reaction vessel and stirred at 22.5 °C and 550 r / min for 85 h. Then, 1.5 g of calcium chloride was added and stirred for 25 h to adsorb impurities. After filtration, the filtrate was evaporated by rotary evaporation to remove the solvent, and the precipitate was placed in ice-cold methanol. After recrystallization, the precipitate was filtered and the filter cake was dried under vacuum at 65 °C for 1.2 h to obtain epoxy-terminated phenyl POSS.

[0030] S3: Add 45g of 3-aminopropyltriethoxysilane and 45mL of ethanol to a reaction vessel, stir for 25min at 22.5℃ and 550r / min, purge with nitrogen to remove oxygen, add 4.5mL of deionized water, heat to 65℃, continue the reaction for 5h, remove ethanol and deionized water by rotary evaporation, and vacuum dry at 65℃ for 1.5h to obtain hyperbranched polysiloxane.

[0031] S4: 11g of epoxy-terminated phenyl POSS and 250mL of tetrahydrofuran were added to the reactor and stirred for 25min at 22.5℃ and 550r / min. Then, 6.96g of hyperbranched polysiloxane and 25mL of anhydrous ethanol were added, and the mixture was heated to 65℃ and reacted for 13h. The mixture was then filtered, and the product was washed three times with tetrahydrofuran, anhydrous ethanol and deionized water. The product was then dried under vacuum at 65℃ for 1.5h to obtain a hydrophobic and oleophobic core-shell packing.

[0032] S5: Mix 24g acrylic emulsion, 13g chitosan, 19g bentonite, 11g microcrystalline cellulose, 8g waterborne polyurethane, 5g hydrophobic and oleophobic core-shell filler, 1.2g glycidyl methacrylate, 3g carboxymethyl cellulose, 0.75g defoamer BYK-024, 0.75g leveling agent BYK-348, and 18g deionized water to form a high-strength waterborne barrier coating with a viscosity of 250mPa·s. Apply the high-strength waterborne barrier coating evenly to the surface of food-grade white cardboard by spraying. Dry and cure under vacuum at 65℃ for 17.5min to obtain a high-strength waterborne barrier coating with a thickness of 11μm.

[0033] Example 3: A high-strength water-based barrier coating, prepared by the following steps: S1: 12g of phenyltriethoxysilane, 4mL of 1mol / L tetrabutylammonium fluoride solution, 10mL of deionized water and 50mL of anhydrous ethanol were added to a reaction vessel and stirred at 25℃ and 600r / min for 90h to form a colorless and transparent solution. Stirring was continued until a white precipitate was formed. After the reaction was completed, the product was filtered, washed 4 times with deionized water, and dried under vacuum at 70℃ for 2h to obtain oligomeric phenyl POSS intermediate.

[0034] S2: 6g of oligophenyl POSS intermediate, 80mL of tetrahydrofuran, 2g of γ-glycidyl etheroxypropyltrimethoxysilane, 0.6g of formic acid, 0.2g of tetrabutylammonium fluoride, 0.3g of tetramethylammonium hydroxide and 6mL of deionized water were added to a reaction vessel and stirred at 25℃ and 600r / min for 90h. Then, 2g of calcium chloride was added and stirred for 26h to adsorb impurities. After filtration, the filtrate was evaporated by rotary evaporation to remove the solvent, placed in ice-cold methanol to precipitate, recrystallized, filtered, and the filter cake was vacuum dried at 70℃ for 2h to obtain epoxy-terminated phenyl POSS.

[0035] S3: Add 46g of 3-aminopropyltriethoxysilane and 50mL of ethanol to a reaction vessel, stir for 30min at 25℃ and 600r / min, purge with nitrogen to remove oxygen, add 5mL of deionized water, heat to 70℃, continue the reaction for 6h, remove ethanol and deionized water by rotary evaporation, and vacuum dry at 70℃ for 2h to obtain hyperbranched polysiloxane.

[0036] S4: 12g of epoxy-terminated phenyl POSS and 300mL of tetrahydrofuran were added to the reactor and stirred for 30min at 25℃ and 600r / min. Then, 7.2g of hyperbranched polysiloxane and 30mL of anhydrous ethanol were added, and the mixture was heated to 70℃ and reacted for 14h. The mixture was then filtered, and the product was washed four times with tetrahydrofuran, anhydrous ethanol and deionized water. The product was then dried under vacuum at 70℃ for 2h to obtain a hydrophobic and oleophobic core-shell packing.

[0037] S5: Mix 25g acrylic emulsion, 14g chitosan, 20g bentonite, 12g microcrystalline cellulose, 9g waterborne polyurethane, 6g hydrophobic and oleophobic core-shell filler, 1.5g glycidyl methacrylate, 4g carboxymethyl cellulose, 1g defoamer BYK-024, 1g leveling agent BYK-348, and 19g deionized water to form a high-strength waterborne barrier coating with a viscosity of 300mPa·s. Apply the high-strength waterborne barrier coating evenly to the surface of food-grade white cardboard by spraying. Dry and cure under vacuum at 70℃ for 20min to obtain a high-strength waterborne barrier coating with a thickness of 12μm.

[0038] Comparative Example 1: Based on Example 3, the epoxy-terminated phenyl POSS in step S4 was replaced with the oligomeric phenyl POSS intermediate prepared in step S1, while the other steps remained unchanged, to prepare a high-strength waterborne barrier coating.

[0039] Comparative Example 2: Based on Example 3, the hyperbranched polysiloxane in step S4 was omitted, while the remaining steps remained unchanged, to prepare a high-strength waterborne barrier coating.

[0040] Comparative Example 3: Based on Example 3, the hydrophobic and oleophobic core-shell filler in step S5 was replaced with the hyperbranched polysiloxane prepared in step S3, while the other steps remained unchanged, to prepare a high-strength waterborne barrier coating.

[0041] Phenylacetoxysilane was purchased from Sigma-Aldrich, CAS No. 780-69-8.

[0042] Chitosan was purchased from Shaanxi Tangyao Biotechnology Co., Ltd., CAS No.: 9012-76-4.

[0043] The bentonite was purchased from Lingshou County Longchuang Mineral Products Co., Ltd., model: KQ-PRT.

[0044] Microcrystalline cellulose was purchased from Shanghai Zhongfeng Biotechnology Co., Ltd., CAS No.: 9004-34-6.

[0045] The white cardboard was purchased from Guangdong Zhanyi Paper Industry Co., Ltd., with a thickness of 0.1mm and a width of 787mm.

[0046] Tetrabutylammonium fluoride was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No.: 429-41-4.

[0047] The acrylic emulsion was purchased from Guangdong Dongda New Material Technology Co., Ltd., model number: SEACRYL11P30.

[0048] The waterborne polyurethane was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., model number: A909856.

[0049] Glycidyl methacrylate was purchased from Jinan Century Tongda Chemical Co., Ltd., CAS No.: 106-91-2, molecular weight: 142.1525.

[0050] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-3. Tear strength was tested according to GB / T 455-2002. Oxygen transmission rate (OTR) was tested according to ASTM F1927 at 23°C and 0%RH, and water vapor transmission rate (WVTR) was tested according to ASTM E96 at 38°C and 90%RH. Oil absorption (Cobb value) was tested within 60 seconds according to GB / T 1540-2002, "Determination of water absorption of paper and paperboard (Cobb method)". Using a DSA100 contact angle meter, 2 μL of soybean oil was added, and the contact angle change within 10 seconds was recorded. The results are shown in Table 1. Table 1 Performance Test Table for High-Strength Waterborne Barrier Coatings As shown in Table 1, the oligophenyl POSS intermediate in Comparative Example 1 lacks epoxy grafting sites, and the hyperbranched polysiloxane cannot be directionally coated on its surface. Due to insufficient steric hindrance of the phenyl groups, the POSS particles undergo self-aggregation, resulting in uneven distribution in the coating and the formation of numerous micropores. The lack of covalent bonds leads to phase separation between POSS and the hyperbranched polysiloxane, preventing the formation of a synergistic effect. This results in a significant decrease in hydrophobic properties and the loss of efficient oleophobic ability. The filler is prone to aggregating, causing a decrease in coating density and a significant increase in oxygen and water vapor permeability. The coating's ability to block water vapor and oxygen is insufficient, failing to effectively delay food oxidation and spoilage due to moisture.

[0051] In Comparative Example 2, the system lacks Si-O-Si siloxane segments with ultra-low surface energy. The phenyl groups alone cannot repel non-polar food oil stains. The coating is only hydrophobic but not oleophobic, and food oil stains can quickly wet and penetrate the coating, contaminating the packaging substrate. Without the steric hindrance and interfacial compatibility of hyperbranched polysiloxanes, the epoxy-terminated phenyl POSS in the water-based coating severely aggregates, forming a large number of interconnected pores inside the coating, causing the barrier performance to collapse. The POSS aggregation prevents the hydrophobic groups from being evenly distributed on the coating surface, resulting in the loss of superhydrophobic properties, and the coating is extremely susceptible to water absorption and moisture.

[0052] In Comparative Example 3, the hyperbranched polysiloxane is a flexible organic chain segment without the reinforcing effect of the POSS cage-type rigid core. The coating strength is low, the structure is loose after film formation, and it cannot form a dense barrier network. It lacks the efficient hydrophobic sites provided by phenyl groups, resulting in a decrease in water contact angle.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A high-strength water-based barrier coating, characterized in that, This high-strength water-based barrier coating is formed by drying and curing a high-strength water-based barrier paint, which comprises the following raw materials by weight: 23-25 ​​parts acrylic emulsion, 12-14 parts chitosan, 18-20 parts bentonite, 10-12 parts microcrystalline cellulose, 7-9 parts waterborne polyurethane, 4-6 parts hydrophobic and oleophobic core-shell filler, 1-1.5 parts glycidyl methacrylate, 2-4 parts carboxymethyl cellulose, 0.5-1 part defoamer, 0.5-1 part leveling agent, and 17-19 parts deionized water; The hydrophobic and oleophobic core-shell filler is obtained by ring-opening addition of epoxy-terminated phenyl POSS with hyperbranched polysiloxane.

2. The high-strength water-based barrier coating according to claim 1, characterized in that, The mass ratio of the epoxy-terminated phenyl POSS to the hyperbranched polysiloxane is (10-12):(6.72-7.2); The ring-opening addition reaction is carried out at a temperature of 60-70℃ for 12-14 hours.

3. The high-strength water-based barrier coating according to claim 1, characterized in that, The epoxy-terminated phenyl POSS is obtained by the silanol condensation reaction of oligomeric phenyl POSS intermediate with γ-glycidoxypropyltrimethoxysilane under the action of a catalyst and then purification. The mass ratio of the oligomeric phenyl POSS intermediate, γ-glycidyl etheroxypropyltrimethoxysilane, and catalyst is (5-6):(1-2):(0.8-1.1).

4. The high-strength water-based barrier coating according to claim 3, characterized in that, The catalyst is obtained by mixing formic acid, tetrabutylammonium fluoride and tetramethylammonium hydroxide in a mass ratio of (4-6):(1.5-2):(2.5-3).

5. The high-strength water-based barrier coating according to claim 3, characterized in that, The temperature of the silanol condensation reaction is 20-25℃, the stirring speed is 500-600 r / min, and the reaction time is 80-90 h.

6. The high-strength water-based barrier coating according to claim 3, characterized in that, The purification method is as follows: calcium chloride is added to the reaction system and stirred for 24-26 hours to adsorb impurities. After filtration, the filtrate is evaporated by rotary evaporation to remove the solvent. The filtrate is then placed in ice-cold methanol to precipitate, recrystallized, filtered, and the filter cake is vacuum dried at 60-70°C for 1-2 hours.

7. The high-strength water-based barrier coating according to claim 3, characterized in that, The oligophenyl POSS intermediate was prepared by the following steps: Phenyltriethoxysilane, a 1 mol / L tetrabutylammonium fluoride solution, deionized water and anhydrous ethanol were added to a reaction vessel and stirred at 20-25℃ and 500-600 r / min for 80-90 h. The precipitate was collected and dried to constant weight to obtain oligomeric phenyl POSS intermediate.

8. A high-strength water-based barrier coating according to claim 7, characterized in that, The ratio of phenyltriethoxysilane, tetrabutylammonium fluoride solution, deionized water and anhydrous ethanol is 10-12g: 2-4mL: 8-10mL: 45-50mL.

9. A high-strength water-based barrier coating according to claim 1, characterized in that, The hyperbranched polysiloxane is obtained by hydrolysis and condensation of 3-aminopropyltriethoxysilane under a nitrogen atmosphere; The hydrolysis-condensation reaction temperature is 60-70℃, and the reaction time is 4-6h.

10. The application of a high-strength water-based barrier coating according to claim 1 in environmentally friendly food paper materials.

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