A fluorine-free water and oil repellent for pulp molding surface impregnation, and a preparation method and use method thereof

Abstract

The present application belongs to the field of pulp molding food packaging waterproof and oil-proof, and particularly relates to a fluorine-free waterproof and oil-proof agent for pulp molding surface impregnation, and a preparation method and use method thereof. The fluorine-free waterproof and oil-proof agent for pulp molding surface impregnation comprises the following raw materials: modified starch 4.4-14.6 parts, amylase 0.02-0.073 parts, edible gelatin 10-20 parts, edible glycerol 3-6 parts, crosslinking agent 0.1-1 part, chitosan 0.3-2.2 parts, acetic acid 0.06-5 parts, deionized water 59-73 parts, and food-grade plasticizer 0.13-0.44 parts. The fluorine-free waterproof and oil-proof agent provided in the present application effectively improves the waterproof and oil-proof performance through hydrogen bond combination, grafting and crosslinking of each component, and also improves the mechanical properties of the pulp molding finished product.

Description

Technical Field

[0001] This invention belongs to the field of waterproof and oil-proof pulp molded food packaging, specifically relating to a fluorine-free waterproof and oil-proof agent for impregnating pulp molded surfaces, its preparation method, and its application method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Pulp molding food packaging is increasingly favored by consumers and the market due to its advantages such as natural source, green and environmentally friendly, safe and hygienic, and easy degradation and recycling. However, this packaging product is mainly composed of natural plant fibers, with hydrophilic cellulose and hemicellulose as the main chemical components. The molecular structure contains a large number of hydroxyl groups, resulting in a loose and porous structure with a certain degree of liquid absorption. It has weak barrier properties against substances such as air, water and oil. At the same time, this packaging product has the problem of poor mechanical strength.

[0004] Adding waterproof and oil-repellent agents to the pulp during the pulp molding process of food packaging can solve the shortcomings of pulp-molded food packaging in terms of water and oil resistance. Fluorinated oil-repellent agents are the most widely used, but recent studies have found that the perfluorinated or polyfluorinated hydrocarbons (PFASs) used in their synthesis are characterized by extremely high persistence and bioaccumulation, and are a class of environmental pollutants with systemic and multi-organ toxicity. Therefore, for the pulp molding food packaging industry, the development of fluorine-free waterproof and oil-repellent agents has become a pressing issue that needs to be addressed. Summary of the Invention

[0005] To overcome the above problems, this invention provides a fluorine-free waterproof and oil-repellent agent for impregnating the surface of molded pulp, along with its preparation and application methods. The fluorine-free waterproof and oil-repellent agent provided in this invention effectively improves the waterproof and oil-repellent properties through hydrogen bonding, grafting, and cross-linking of its components, while also enhancing the mechanical properties of the molded pulp product.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the raw materials of which include:

[0008] Modified starch 4.4–14.6 parts, amylase 0.02–0.073 parts, edible gelatin 10–20 parts, edible glycerol 3–6 parts, crosslinking agent 0.1–1 part, chitosan 0.3–2.2 parts, acetic acid 0.06–5 parts, deionized water 59–73 parts, food-grade plasticizer 0.13–0.44 parts.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the preparation method comprising:

[0010] (1) Dissolve the modified starch in deionized water, then add amylase, stir and hydrolyze for a period of time, then incubate and inactivate to obtain mixed solution A;

[0011] (2) Add edible glycerin to edible gelatin, heat and stir until the edible gelatin is completely dissolved into a uniform viscous state, then add crosslinking agent and chitosan acetic acid solution, stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0012] (3) Mix solution A and mixed solution B together, and then add food-grade plasticizer; after mixing evenly, obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0013] A third aspect of the present invention provides a method of using the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the method comprising:

[0014] The pulp molded blank is immersed in the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of the pulp molded blank. It is then quickly removed, rotated to remove excess fluorine-free waterproof and oil-repellent agent, and hot-pressed and dried to obtain the finished pulp molded product.

[0015] The beneficial effects of this invention are as follows:

[0016] (1) Modified starch, as the main component of fluorine-free waterproof and oil-repellent agent, is enzymatically hydrolyzed to generate amylopectin with small size, which can effectively penetrate into the fine pores of the pulp molding surface and bind tightly with the fibers; edible gelatin has highly active side chain reactive groups, which can form ionic and covalent bonds with a large number of hydroxyl groups and a small number of carboxyl groups on the fibers. The formation of these bonds increases the bonding force between paper fibers and the bond energy, thereby improving the mechanical strength of the paper; the crosslinking agent contains abundant phenolic hydroxyl groups, which will produce crosslinking reactions with edible gelatin groups, and crosslinking between the edible gelatin macromolecules The formation of a tight network structure between molecules tightens the gaps between molecules, making it difficult for water molecules to penetrate the oil-resistant, oil-repellent-reinforced molding surface film matrix. The tortuous channels require water molecules to travel a longer distance to pass through the edible film. Hydrogen bonds are formed between chitosan and cellulose, which have strong binding forces. At the same time, chitosan has good film-forming properties, further improving the molding performance of pulp. During the high-temperature hot-pressing and drying process of pulp molding, food-grade plasticizers can esterify and neutralize the remaining hydroxyl groups, reducing the hydrophilicity of the molding surface and lengthening the hydroxyl side chain, thereby enhancing the mechanical strength of the pulp molding.

[0017] (2) The fluorine-free waterproof and oil-repellent agent for impregnating the pulp molding surface described in this invention uses fluorine-free raw materials, is safe and environmentally friendly, and will not produce toxic or harmful substances to the human body. It is a healthy and environmentally friendly waterproof and oil-repellent agent.

[0018] (3) The fluorine-free waterproof and oil-proof agent for impregnating the pulp molding surface described in this invention can achieve good waterproof and oil-proof effects, and improve the mechanical strength of the molding. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of this application. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a flowchart illustrating the preparation and application method of the fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding according to the present invention. Detailed Implementation

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] A first typical embodiment of the present invention provides a fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the raw materials of which include:

[0024] Modified starch 4.4–14.6 parts, amylase 0.02–0.073 parts, edible gelatin 10–20 parts, edible glycerol 3–6 parts, crosslinking agent 0.1–1 part, chitosan 0.3–2.2 parts, acetic acid 0.06–5 parts, deionized water 59–73 parts, food-grade plasticizer 0.13–0.44 parts.

[0025] In one or more embodiments, the modified starch is selected from one or more of cationic starch, anionic starch, corn starch or tapioca starch; preferably cationic starch.

[0026] In one or more embodiments, the crosslinking agent is selected from one or more of riboflavin, tannin, and genipin; preferably tannin.

[0027] In one or more embodiments, the food-grade plasticizer is an acetylated mono- and diglyceride fatty acid ester.

[0028] A second aspect of the present invention provides a method for preparing the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the preparation method comprising:

[0029] (1) Dissolve the modified starch in deionized water, then add amylase, stir and hydrolyze for a period of time, then incubate and inactivate to obtain mixed solution A;

[0030] (2) Add edible glycerin to edible gelatin, heat and stir until the edible gelatin is completely dissolved into a uniform viscous state, then add crosslinking agent and chitosan acetic acid solution, stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0031] (3) Mix solution A and mixed solution B together, and then add food-grade plasticizer; after mixing evenly, obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0032] In one or more embodiments, the temperature of the stirring enzymatic hydrolysis in step (1) is 85-90°C, preferably 88°C, and the hydrolysis time is 25-35 min, preferably 30 min.

[0033] In one or more embodiments, the temperature for heat preservation and inactivation in step (1) is 90-100°C, preferably 95°C, and the inactivation time is 15-25 min, preferably 20 min.

[0034] In one or more embodiments, the heating and stirring temperature in step (2) is 55-65°C, preferably 60°C.

[0035] In one or more embodiments, in step (2), the mass fraction of chitosan solute in the chitosan acetic acid solution is 3-6%, preferably 5%; and the mass fraction of acetic acid solute is 0.5-1.5%, preferably 1%.

[0036] In one or more embodiments, the method for mixing the food-grade plasticizer after adding it in step (3) is as follows: homogenize 2 to 3 times under a pressure of 30 Bar using a high-pressure homogenizer.

[0037] A third typical embodiment of the present invention provides a method of using the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, the method comprising:

[0038] The pulp molded blank is immersed in the above-mentioned fluorine-free waterproof and oil-repellent agent for impregnating the surface of the pulp molded blank. It is then quickly removed, rotated to remove excess fluorine-free waterproof and oil-repellent agent, and hot-pressed and dried to obtain the finished pulp molded product.

[0039] In one or more embodiments, the fluorine-free waterproof and oil-repellent agent for impregnating the pulp molding surface is diluted with water before use. The specific dilution ratio (mass ratio of the fluorine-free waterproof and oil-repellent agent for impregnating the pulp molding surface to water) is 1:2 to 5, preferably 1:3.

[0040] In one or more embodiments, the hot-press drying conditions are as follows: the upper mold temperature of the molding machine is 180-190°C, preferably 185°C; the lower mold temperature is 190-200°C, preferably 195°C; and hot pressing is performed at a pressure of 500 pis for 1 minute.

[0041] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0042] Example 1

[0043] 4.6 parts of modified starch were dissolved in 23 parts of deionized water, and then 0.023 parts of amylase were added. The mixture was heated in a water bath at 88°C and stirred for 30 minutes for enzymatic hydrolysis. Then the temperature was raised to 95°C and kept warm for 20 minutes for inactivation to obtain mixed solution A.

[0044] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.1 parts of tannin and 14 parts of chitosan acetic acid solution (0.7 parts of chitosan and 0.14 parts of acetic acid), stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0045] Mixed solution A and mixed solution B are blended together, and then 0.138 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added; the mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0046] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0047] Example 2

[0048] 4.7 parts of modified starch were dissolved in 23.5 parts of deionized water, and then 0.0235 parts of amylase were added. The mixture was stirred and hydrolyzed for 30 minutes under the condition of water bath heating and keeping at 88°C. Then the temperature was raised to 95°C and kept at 95°C for 20 minutes to inactivate the enzyme, thus obtaining mixed solution A.

[0049] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.3 parts of tannin and 14 parts of chitosan acetic acid solution (0.7 parts of chitosan and 0.14 parts of acetic acid), stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0050] Mixed solution A and mixed solution B are blended together, and then 0.141 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added; the mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0051] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0052] Example 3

[0053] Dissolve 6.9 parts of modified starch in 34.5 parts of deionized water, then add 0.0345 parts of amylase, stir and hydrolyze for 30 min under water bath heating and keeping at 88℃, then raise the temperature to 95℃ and keep at 95℃ for 20 min to inactivate, to obtain mixed solution A;

[0054] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.3 parts of tannin and 10 parts of chitosan acetic acid solution (0.5 parts of chitosan and 0.1 parts of acetic acid) and stir to react. After the reaction is complete, cool to obtain mixed solution B.

[0055] Mixed solution A and mixed solution B are blended together, and then 0.138 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added; the mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0056] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0057] Example 4

[0058] Dissolve 6.8 parts of modified starch in 34 parts of deionized water, then add 0.034 parts of amylase, stir and hydrolyze for 30 min under water bath heating and keeping at 88℃, then raise the temperature to 95℃ and keep at 95℃ for 20 min to inactivate, to obtain mixed solution A;

[0059] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.3 parts of tannin and 6 parts of chitosan-acetic acid solution (0.3 parts of chitosan and 0.06 parts of acetic acid) and stir to react. After the reaction is complete, cool to obtain mixed solution B.

[0060] Mixed solution A and mixed solution B are blended together, and then 0.132 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added. The mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0061] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0062] Example 5

[0063] 6.95 parts of modified starch were dissolved in 34.75 parts of deionized water, and then 0.035 parts of amylase were added. The mixture was stirred and enzymatically hydrolyzed for 30 minutes under the condition of water bath heating and keeping at 88°C, and then heated to 95°C and kept at 95°C for 20 minutes to inactivate the enzyme, thus obtaining mixed solution A.

[0064] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.4 parts of tannin and 10 parts of chitosan acetic acid solution (0.5 parts of chitosan and 0.1 parts of acetic acid), stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0065] Mix solution A and mixed solution B together, then add 0.209 parts of food-grade plasticizer; homogenize 2-3 times at 30 Bar using a high-pressure homogenizer to mix them evenly, and obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0066] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0067] Example 6

[0068] 7.24 parts of modified starch were dissolved in 36.2 parts of deionized water, and then 0.036 parts of amylase were added. The mixture was stirred and hydrolyzed for 30 minutes under the condition of water bath heating and keeping at 88°C. Then the temperature was raised to 95°C and kept at 95°C for 20 minutes to inactivate the enzyme, thus obtaining mixed solution A.

[0069] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.5 parts of tannin and 20 parts of chitosan-acetic acid solution (1 part of chitosan and 0.2 parts of acetic acid), stir and react, and cool after the reaction is complete to obtain mixed solution B;

[0070] Mix solution A and mixed solution B together, then add 0.29 parts of food-grade plasticizer; homogenize 2-3 times at 30 Bar using a high-pressure homogenizer to mix them evenly, and obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0071] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0072] Comparative Example 1 (no crosslinking agent added compared to Example 3)

[0073] Dissolve 6.9 parts of modified starch in 34.5 parts of deionized water, then add 0.0345 parts of amylase, stir and hydrolyze for 30 min under water bath heating and keeping at 88℃, then raise the temperature to 95℃ and keep at 95℃ for 20 min to inactivate, to obtain mixed solution A;

[0074] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 10 parts of chitosan acetic acid solution (0.5 parts of chitosan and 0.1 parts of acetic acid) and stir to react. After the reaction is complete, cool to obtain mixed solution B.

[0075] Mixed solution A and mixed solution B are blended together, and then 0.138 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added; the mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0076] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0077] Comparative Example 2 (no chitosan added compared to Example 3)

[0078] Dissolve 6.9 parts of modified starch in 34.5 parts of deionized water, then add 0.0345 parts of amylase, stir and hydrolyze for 30 min under water bath heating and keeping at 88℃, then raise the temperature to 95℃ and keep at 95℃ for 20 min to inactivate, to obtain mixed solution A;

[0079] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.3 parts of tannin and stir to react. After the reaction is complete, cool to obtain mixed solution B.

[0080] Mixed solution A and mixed solution B are blended together, and then 0.138 parts of food-grade plasticizer acetylated mono- and diglyceride fatty acid esters are added; the mixture is homogenized 2 to 3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0081] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0082] Comparative Example 3 (without the addition of food-grade plasticizers compared to Example 3)

[0083] Dissolve 6.9 parts of modified starch in 34.5 parts of deionized water, then add 0.0345 parts of amylase, stir and hydrolyze for 30 min under water bath heating and keeping at 88℃, then raise the temperature to 95℃ and keep at 95℃ for 20 min to inactivate, to obtain mixed solution A;

[0084] Add 3 parts of edible glycerin to 10 parts of edible gelatin, heat and stir at 60°C until the edible gelatin is completely dissolved into a uniform viscous state, then add 0.3 parts of tannin and 10 parts of chitosan acetic acid solution (0.5 parts of chitosan and 0.1 parts of acetic acid) and stir to react. After the reaction is complete, cool to obtain mixed solution B.

[0085] Mixed solution A and mixed solution B are blended and homogenized 2-3 times under 30 Bar pressure using a high-pressure homogenizer to obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

[0086] The pulp molding blank (bagasse: bamboo pulp ratio of 6:4, 8-inch size, 18g) was immersed in a 3-fold diluted solution of the fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation prepared in this embodiment. It was quickly taken out and rotated to remove excess oil-repellent agent. The weight gain of the pulp molding blank was controlled to be 3g. The upper mold temperature was 185℃ and the lower mold temperature was 195℃. It was hot-pressed at 500pis pressure for 1 minute to obtain the finished pulp molding product.

[0087] Experimental Example 1

[0088] The paper pulp molded tableware prepared in Examples 1-6 and Comparative Examples 1-3 of the present invention, as well as the paper pulp molded blanks of the blank control, were tested for their waterproof and hot oil-resistant properties. The test results are shown in Table 1.

[0089] Waterproof performance: The penetration time is tested by pouring 80°C hot water into the molded product at room temperature.

[0090] Hot oil resistance performance: The penetration time is tested by pouring 80°C hot oil into the molded product at room temperature.

[0091] Mechanical properties: Tensile index test according to GB / T 12914-2018; tear index test according to GB / T455-2002; compressive strength record the pressure value when the flat paper tray is crushed by the compression tester and cracks appear.

[0092] Table 1 Performance of Surface Impregnation Test Samples

[0093]

[0094] The comparison of the performance test results of the samples in Examples 1 to 6 with the blank sample shows that the interaction of starch, edible gelatin, edible glycerin, crosslinking agent (tannin), chitosan and food-grade plasticizer makes pulp molding exhibit excellent effects in terms of water and oil resistance as well as mechanical properties.

[0095] Compared with Example 3, Comparative Example 1 did not add a crosslinking agent and found that its waterproof, oil-proof, and mechanical properties were all reduced. This is because without the addition of a crosslinking agent, it is impossible to produce a crosslinking reaction with edible gelatin. Therefore, a tight network structure cannot be formed between the macromolecules of edible gelatin, making it easy for water molecules to penetrate through the molded surface film matrix reinforced by the oil-proof agent. As a result, its waterproof, oil-proof, and mechanical properties are all reduced.

[0096] Compared with Example 3, Comparative Example 2 did not add chitosan, and it was found that the waterproof and oil-proof properties as well as the mechanical properties were reduced. This is because hydrogen bonds are formed between chitosan and cellulose, and chitosan has excellent film-forming properties, which can improve the molding properties of pulp. Without chitosan, the corresponding properties will be reduced.

[0097] Compared with Example 3, Comparative Example 2 did not add food-grade plasticizer, and it was found that the waterproof, oil-proof and mechanical properties were reduced. This is because food-grade plasticizer can esterify and neutralize the remaining hydroxyl groups during the high-temperature hot-pressing and drying process of pulp molding, thereby reducing the hydrophilicity of the molded surface. At the same time, it increases the length of the hydroxyl side chain, thereby enhancing the mechanical strength of the pulp molding. Without food-grade plasticizer, the corresponding properties will be reduced.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding, characterized in that, Raw materials include: Modified starch 4.6~14.6 parts, amylase 0.02~0.073 parts, edible gelatin 10~20 parts, edible glycerin 3~6 parts, crosslinking agent 0.1~1 part, chitosan 0.3~2.2 parts, acetic acid 0.06~5 parts, deionized water 59~73 parts, food-grade plasticizer 0.13~0.44 parts; The crosslinking agent is selected from one or more of riboflavin, tannin, and genipin; The food-grade plasticizer is an acetylated mono- and diglyceride fatty acid ester; The modified starch is selected from one or more of cationic starch, anionic starch, corn starch or tapioca starch; The method of using the fluorine-free waterproof and oil-repellent agent includes: The pulp molding blank is immersed in the above-mentioned fluorine-free waterproof and oil-repellent agent for pulp molding surface impregnation, quickly taken out and rotated to remove excess fluorine-free waterproof and oil-repellent agent, and then hot-pressed and dried to obtain the pulp molding finished product. The hot-press drying conditions are as follows: upper mold temperature of 180~190℃; lower mold temperature of 190~200℃; hot pressing for 1 minute at 500psi pressure.

2. The fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding as described in claim 1, characterized in that, The modified starch is cationic starch.

3. The fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding as described in claim 1, characterized in that, The crosslinking agent is tannin.

4. The fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding as described in claim 1, characterized in that, The fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding is diluted with water before use. The mass ratio of the fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding to water is 1:2~5.

5. The fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding as described in claim 1, characterized in that, The fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding is diluted with water before use. The mass ratio of the fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding to water is 1:

3. Alternatively, the hot-press drying conditions are: upper mold temperature of 185℃ and lower mold temperature of 195℃.

6. A method for preparing a fluorine-free waterproof and oil-repellent agent for impregnating the surface of pulp molding as described in any one of claims 1 to 3, characterized in that, The preparation method includes: (1) Dissolve the modified starch in deionized water, then add amylase, stir and hydrolyze for a period of time, then incubate and inactivate to obtain mixed solution A; (2) Add edible glycerin to edible gelatin, heat and stir until the edible gelatin is completely dissolved into a uniform viscous state, then add crosslinking agent and chitosan acetic acid solution, stir and react, and cool after the reaction is complete to obtain mixed solution B; (3) Mix solution A and mixed solution B together, and then add food-grade plasticizer; after mixing evenly, obtain a fluorine-free waterproof and oil-resistant agent for impregnating the surface of pulp molding.

7. The preparation method according to claim 6, characterized in that, In step (1), the temperature for stirring and enzymatic hydrolysis is 85~90℃, and the time for enzymatic hydrolysis is 25~35min; Alternatively, the inactivation temperature in step (1) is 90~100℃, and the inactivation time is 15~25min.

8. The preparation method according to claim 6, characterized in that, In step (1), the temperature for stirring and enzymatic hydrolysis is 88°C, and the time for enzymatic hydrolysis is 30 min. Alternatively, the inactivation temperature in step (1) is 95°C and the inactivation time is 20 min.

9. The preparation method according to claim 6, characterized in that, The heating and stirring temperature in step (2) is 55~65℃; Alternatively, in step (2), the mass fraction of chitosan solute in the chitosan acetic acid solution is 3-6% and the mass fraction of acetic acid solute is 0.5-1.5%.

10. The preparation method according to claim 6, characterized in that, The heating and stirring temperature in step (2) is 60°C; Alternatively, in step (2), the chitosan solute in the acetic acid solution has a mass fraction of 5% and the acetic acid solute has a mass fraction of 1%.

11. The preparation method according to claim 6, characterized in that, The method for mixing the food-grade plasticizer after adding it in step (3) is as follows: homogenize it 2-3 times under a pressure of 30 Bar using a high-pressure homogenizer.

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