A high-strength paper-based packaging material and a method for producing the same

Abstract

The application belongs to the field of paper-based materials, and provides a high-strength paper-based packaging material and a preparation method thereof. First, a water-based polyurethane with complete biodegradability and better strength modification effect is developed by using polyester polyol as a reaction soft segment and using completely degradable composite monomers (DMPA and BDO) as raw materials, and then the water-based polyurethane is compounded with dialdehyde starch-PVA to prepare a high-strength paper-based packaging material, which comprises: the base paper is loaded with at least one dialdehyde starch / PVA layer; the dialdehyde starch / PVA layer is loaded with at least one water-based polyurethane layer; and the raw material of the dialdehyde starch / PVA layer is composed of the following raw materials in parts by weight: dialdehyde starch 1-6 parts, PVA 1-3 parts. The application develops a coating layer with high strength, so as to perform surface modification on paper and give the paper sufficient mechanical properties to meet the demand of replacing plastic products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of paper-based materials, and particularly relates to a high-strength paper-based packaging material and a preparation method thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the application without admitting that such information forms prior art.

[0003] Plastics are indispensable high molecular materials in modern life. The production of plastics reached 360 million tons as early as 2018, and is expected to reach 12 billion tons by 2050. However, the recycling rate of plastics is less than 10%, and the waste plastics that cannot be degraded have caused serious pollution to the ecological environment. The discarded plastics are washed by rivers and accumulated in the ocean. It is reported that a large amount of plastic waste has accumulated in the ocean, and it will take at least 300 years to degrade from micron scale to nanometer scale, thereby causing serious marine microplastic pollution problems.

[0004] Based on the overuse of plastic products, the pollution to the environment and the consumption of resources, it is imperative to replace plastics with paper. Compared with plastics, the environmental advantages of paper are more obvious, but the mechanical properties are far inferior to those of plastics.

[0005] At present, the industry often adds inorganic fillers, adds polymers in pulp, surface sizing, surface dissolution, nanofiber coating and other methods to improve the strength of paper. Among them, polyester emulsion (PU) is a high-efficiency and commercial surface sizing agent and has been widely used. However, the inventors found that most commercial waterborne polyurethane products currently use polyether polyols as soft segments, and petroleum-based raw materials to synthesize products with poor biodegradability. While facilitating people's daily life, it inevitably causes harm to the environment. SUMMARY

[0006] In order to solve the above problems, the present application provides a high-strength paper-based packaging material and a preparation method thereof. The present application fully considers the comprehensive conditions of practicability, degradability, safety and economy, uses polyester polyol as the reaction soft segment, and uses completely degradable composite monomers (DMPA and BDO) as raw materials to develop a waterborne polyurethane product with complete biodegradability. Compared with commercial polyurethane products, the waterborne polyurethane of the present application can better improve the tensile strength and tear strength of paper, and the completely degradable product of the present application is environmentally friendly.

[0007] In another aspect, in order to prepare a high-strength paper-based packaging material, the present application has carried out a large number of experimental screening on the combination of the above-mentioned water-based polyurethane and various different components such as dialdehyde starch, polyvinyl alcohol, commercial polyester emulsion (ADM-2133, ADM-2466, ADM-206), silane coupling agent (KH-570, KH-550, KH-792), ammonia water, vinyl acetate resin, polyhydroxyalkanoate, methacrylic acid resin, cationic starch, soybean protein, silicon dioxide, etc., and found that: by compounding easily available commercial products: dialdehyde starch, polyvinyl alcohol, and the above-mentioned water-based polyurethane, a multi-layer coating is constructed to modify the surface of the paper, which can significantly improve the strength of the paper.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] In a first aspect of the present application, a water-based polyurethane is provided, comprising:

[0010] The polycaprolactone PCL is mixed with 2,2-dimethylol propionic acid DMPA and 1,4-butanediol BDO in a mass ratio of 5-84.15:0.47-7.65:0.876-29.455, uniformly mixed, and reacted to obtain an intermediate product.

[0011] The intermediate product is reacted with toluene diisocyanate TDI, and after the reaction is completed, triethanolamine TEA is added for neutralization reaction, and after the reaction is completed, emulsification is performed to obtain a water-based polyurethane.

[0012] The synthesis route is as follows:

[0013]

[0014] Preferably, the mass ratio of the PCL, TDI and TEA is 5-84.15:3-74.17:0.355-5.711.

[0015] Further, based on the above-mentioned water-based polyurethane, the present application provides a high-strength paper-based packaging material, comprising:

[0016] A base paper;

[0017] The base paper is loaded with at least one dialdehyde starch-PVA layer;

[0018] The dialdehyde starch-PVA layer is loaded with at least one water-based polyurethane layer;

[0019] The dialdehyde starch-PVA layer is composed of the following raw materials in parts by weight: dialdehyde starch 1-6 parts, PVA 1-3 parts;

[0020] Preferably, the wet film thickness of each layer is 10-50 μm.

[0021] At present, due to the different properties of various paper surface sizing agents, the effects after compounding are quite different, and the industry has not found a suitable sizing agent combination to simultaneously meet the requirements of high-strength paper-based packaging material tensile strength and tear resistance. Therefore, through systematic research and long-term experimental exploration, it is found that: by compounding easily available commercial products: dialdehyde starch, polyvinyl alcohol and water-based polyurethane, a multi-layer coating is constructed to modify the surface of the paper, which can significantly improve the strength of the paper.

[0022] The second aspect of the application provides a preparation method of high-strength paper-based packaging material, comprising:

[0023] The dialdehyde starch is mixed with water uniformly and placed at 60-90 DEG C for stirring for 1-1.5h to obtain gelatinized starch;

[0024] The gelatinized starch is mixed with PVA uniformly to obtain a dialdehyde starch-PVA mixture;

[0025] The dialdehyde starch-PVA mixture is coated on the surface of the paper-based material and dried to obtain a raw paper loaded with a dialdehyde starch / PVA layer;

[0026] The raw paper loaded with the dialdehyde starch-PVA layer is coated with a polyester emulsion and dried.

[0027] The third aspect of the application provides the application of the above-mentioned paper-based packaging material in the fields of food, cold chain, daily chemical, and medicine.

[0028] The beneficial effects of the application

[0029] (1) The application fully considers the comprehensive conditions of practicability, degradability, safety and economy, uses polyester polyol as the reaction soft segment, and uses completely degradable composite monomers (DMPA and BDO) as raw materials to develop a water-based polyurethane product with complete biodegradability. Compared with commercial polyurethane products, the water-based polyurethane of the application can better improve the tensile strength and tear strength of the paper, and the completely degradable product of the application is environmentally friendly.

[0030] (2) Compared with the use of water-based polyurethane alone, the application first coats one to two layers of dialdehyde starch-PVA coating on the surface of the paper, which can improve the strength of the paper, at the same time, the dialdehyde starch-PVA coating can effectively reduce the penetration of water-based polyurethane on the paper, improve the internal bonding force of the paper, and obtain better tensile strength and tear resistance.

[0031] (3) The present application further selects the coating combination with larger paper strength improvement through the detection of the modified paper related indexes: a coating layer is prepared based on 30wt% of dialdehyde starch and 10wt% of polyvinyl alcohol, which is compounded according to a mass ratio of 1:1, the obtained coating layer is uniformly coated on the paper twice, and after drying, the water-based polyurethane prepared by the present application is uniformly coated on the paper twice, so that the tensile strength can reach 3.49KN / m, which is increased by 71.9% compared with the original paper, and the tear strength is as high as 2573mN, which is increased by 730% compared with the original paper.

[0032] (4) The present application has simple preparation method, strong practicability and easy popularization. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0034] A high-strength paper-based packaging material, comprising:

[0035] A base paper;

[0036] At least one dialdehyde starch-PVA layer is loaded on the base paper;

[0037] At least one water-based polyurethane layer is loaded on the dialdehyde starch-PVA layer;

[0038] The dialdehyde starch-PVA layer is composed of the following raw materials in parts by weight: dialdehyde starch 1-6 parts, PVA 1-3 parts.

[0039] In some embodiments, the wet film thickness of each coating layer is 10-50μm.

[0040] In some embodiments, the dialdehyde starch-PVA layer is provided with 1-3 layers.

[0041] In some embodiments, the water-based polyurethane layer is provided with 1-3 layers.

[0042] A preparation method of a high-strength paper-based packaging material, comprising:

[0043] Mixing dialdehyde starch and water uniformly, placing in 60-90℃ for 1-1.5h stirring, obtaining gelatinized starch;

[0044] Mixing the gelatinized starch and PVA uniformly to obtain a dialdehyde starch-PVA mixture;

[0045] Coating the dialdehyde starch-PVA mixture onto the surface of the paper-based material, drying, obtaining a base paper loaded with a dialdehyde starch-PVA layer;

[0046] Coating the base paper with the load dialdehyde starch-PVA layer with water-based polyurethane, drying, and obtaining.

[0047] In some embodiments, the concentration of the dialdehyde starch is 25wt%-30wt%.

[0048] In some embodiments, the concentration of the PVA is 10wt%-12wt%.

[0049] In some embodiments, a plurality of dialdehyde starch-PVA layers are loaded on the base paper with the load dialdehyde starch-PVA layer.

[0050] In some embodiments, a plurality of water-based polyurethane layers are loaded on the base paper with the load dialdehyde starch-PVA layer.

[0051] The application will be further described in detail below with specific examples, it should be pointed out that the specific examples are an explanation of the application rather than a limitation.

[0052] In the following examples, dialdehyde starch, polyvinyl alcohol, methacrylic acid resin, and polyester emulsion are all commercially available products, wherein the polyester emulsion (ADM-2133) is purchased from Shandong Aodemei High Molecular Material Co., Ltd.

[0053] Example 1

[0054] 1) 5g PCL, 0.47g DMPA (2,2-dimethylol propionic acid), and 1.995g BDO (1,4-butanediol) were mixed uniformly, reacted at 30℃ for 20min, 4.9g TDI (toluene diisocyanate) was added, warmed to 80℃, reacted for 5h, cooled to 40℃, TEA (0.355g) was added, stirred for 30min, and water emulsified for 1h, to obtain a water-based polyurethane resin (WPU) (acid content 3.7%);

[0055] 2) The degradable polyester emulsion WPU was coated on the base paper by using a wire bar coater, and the single-layer coating amount was 8g / m 2 , to obtain a biodegradable green and environmentally friendly coating.

[0056] Example 2

[0057] 1) 8g PCL, 0.47g DMPA, and 0.876g BDO were mixed uniformly, reacted at 30℃ for 20min, 3g TDI was added, warmed to 80℃, reacted for 5h, cooled to 40℃, TEA (0.355g) was added, stirred for 30min, and water emulsified for 1h, to obtain WPU (acid content 3.7%);

[0058] 2) The degradable polyester emulsion WPU is coated on the base paper by using a wire bar coater, and the single-layer coating amount is 8 g / m 2 , to obtain a biodegradable green and environmentally friendly coating.

[0059] Example 3

[0060] 1) 7 g of PCL, 0.5 g of DMPA and 1.16 g of BDO are uniformly mixed, reacted at 30°C for 20 min, 3.5 g of TDI is added, warmed to 80°C, reacted for 5 h, cooled to 40°C, TEA (0.377 g) is added and stirred for 30 min, and water is added for emulsification for 1 h to obtain WPU (acid content is 4%);

[0061] 2) The degradable polyester emulsion WPU is coated on the base paper by using a wire bar coater, and the single-layer coating amount is 8 g / m 2 , to obtain a biodegradable green and environmentally friendly coating.

[0062] Example 4

[0063] 1) 84.15 g of PCL, 7.65 g of DMPA and 29.445 g of BDO are uniformly mixed, reacted at 30°C for 20 min, 74.17 g of TDI is added, warmed to 80°C, reacted for 5 h, cooled to 40°C, TEA (5.771 g) is added and stirred for 30 min, and water is added for emulsification for 2 h to obtain WPU (acid content is 3.8%).

[0064] 2) The degradable polyester emulsion WPU is coated on the base paper by using a wire bar coater, and the single-layer coating amount is 8 g / m 2 , to obtain a biodegradable green and environmentally friendly coating.

[0065] Example 5

[0066] 1) The dialdehyde starch (30%) is prepared by placing dialdehyde starch (30%) and deionized water in a beaker according to a weight ratio of 3:7, and stirring at 60°C for 1 h;

[0067] 2) The dialdehyde starch (30%) is mixed with 10% PVA aqueous solution according to a mass ratio of 1:1 to obtain a dialdehyde starch (30%) -PVA mixed solution;

[0068] 3) The dialdehyde starch (30%) -PVA mixed solution is uniformly coated on the base paper by using a wire bar coater, the coating bar specification is 50 μm, and natural drying is performed to obtain a dialdehyde starch (30%) -PVA coating (1:1).

[0069] Example 6

[0070] 1) dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to the weight ratio of 3:7, and stirred at 60°C for 1h to prepare dialdehyde starch (30%);

[0071] 2) dialdehyde starch (30%) was compounded with 10% PVA aqueous solution according to the mass ratio of 1:3, and mixed uniformly to obtain dialdehyde starch (30%) -PVA mixed solution;

[0072] 3) dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper once by wire bar coater, the coating rod specification was 50μm, and natural drying was carried out to obtain dialdehyde starch (30%) -PVA coating (1:3).

[0073] Example 7

[0074] 1) dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to the weight ratio of 3:7, and stirred at 60°C for 1h to prepare dialdehyde starch (30%);

[0075] 2) dialdehyde starch (30%) was compounded with 10% PVA aqueous solution according to the mass ratio of 3:1, and mixed uniformly to obtain dialdehyde starch (30%) -PVA mixed solution;

[0076] 3) dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper once by wire bar coater, the coating rod specification was 50μm, and natural drying was carried out to obtain dialdehyde starch (30%) -PVA coating (3:1).

[0077] Example 8

[0078] 1) dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to the weight ratio of 3:7, and stirred at 60°C for 1h to prepare dialdehyde starch (30%);

[0079] 2) dialdehyde starch (30%) was compounded with 10% PVA aqueous solution according to the mass ratio of 6:1, and mixed uniformly to obtain dialdehyde starch (30%) -PVA mixed solution;

[0080] 3) dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper once by wire bar coater, the coating rod specification was 50μm, and natural drying was carried out to obtain dialdehyde starch (30%) -PVA coating (6:1).

[0081] Example 9

[0082] 1) dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to the weight ratio of 3:7, and stirred at 60°C for 1h to prepare dialdehyde starch (30%);

[0083] 2) The dialdehyde starch (30%) and 10% PVA aqueous solution were mixed according to a mass ratio of 1:1, and uniformly mixed to obtain a dialdehyde starch (30%) -PVA mixed solution;

[0084] 3) The dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper twice by a wire bar coater, the coating rod specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) -PVA coating (2 layers).

[0085] Example 10

[0086] 1) The dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to a weight ratio of 3:7, and stirring was performed at 60°C for 1 h to prepare dialdehyde starch (30%);

[0087] 2) The dialdehyde starch (30%) and 10% PVA aqueous solution were mixed according to a mass ratio of 1:1, and uniformly mixed to obtain a dialdehyde starch (30%) -PVA mixed solution;

[0088] 3) The dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper twice by a wire bar coater, the coating rod specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) -PVA coating (2 layers).

[0089] 4) The water-based polyurethane prepared in Example 10 was uniformly coated on the dialdehyde starch (30%) -PVA coating (1:1) obtained in step 3) once by a wire bar coater, the coating rod specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) -PVA = 1:1 (1 layer) + PU coating (1 layer).

[0090] Example 11

[0091] 1) The dialdehyde starch (30%) dialdehyde starch and deionized water were placed in a beaker according to a weight ratio of 3:7, and stirring was performed at 60°C for 1 h to prepare dialdehyde starch (30%);

[0092] 2) The dialdehyde starch (30%) and 10% PVA aqueous solution were mixed according to a mass ratio of 1:1, and uniformly mixed to obtain a dialdehyde starch (30%) -PVA mixed solution;

[0093] 3) The dialdehyde starch (30%) -PVA mixed solution was uniformly coated on the base paper twice by a wire bar coater, the coating rod specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) -PVA coating (2 layers).

[0094] 4) The aqueous polyurethane prepared in Example 10 was uniformly coated twice on the dialdehyde starch (30%) - PVA coating (2 layers) obtained in step 3) by using a wire bar coater, the coating bar specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) - PVA = 1:1 (2 layers) + PU coating (2 layers).

[0095] Comparative Example 1

[0096] The polyester emulsion was uniformly coated once on the base paper by using a wire bar coater, the coating bar specification was 50 μm, and natural drying was performed to obtain a PU coating (1 layer).

[0097] Comparative Example 2

[0098] The polyester emulsion was uniformly coated twice on the PU coating of Comparative Example 1 by using a wire bar coater, the coating bar specification was 50 μm, and natural drying was performed to obtain a PU coating (2 layers).

[0099] Comparative Example 3

[0100] 1) Dialdehyde starch (30%) was prepared by placing dialdehyde starch (30%) and deionized water in a beaker at a weight ratio of 3:7, and placing the beaker at 60°C for stirring for 1 h;

[0101] 2) Dialdehyde starch (30%) was mixed with 10% PVA aqueous solution at a mass ratio of 1:1 to obtain a dialdehyde starch (30%) - PVA mixture;

[0102] 3) The dialdehyde starch (30%) - PVA mixture was uniformly coated once on the base paper by using a wire bar coater, the coating bar specification was 50 μm, and natural drying was performed to obtain a dialdehyde starch (30%) - PVA coating (1:1).

[0103] 4) The methacrylic acid resin was uniformly coated once on the dialdehyde starch (30%) - PVA coating (1:1) obtained in step 3) by using a wire bar coater, the coating bar specification was 50 μm, and natural drying was performed to obtain dialdehyde starch (30%) - PVA = 1:1 (1 layer) + methacrylic acid coating (1 layer).

[0104] Experimental Example

[0105] In Examples 1-3, the present application fully considers the comprehensive conditions of practicability, degradability, safety, and economy, uses polyester polyol as the reaction soft segment, and uses completely degradable monomers as raw materials to develop an aqueous polyurethane product that is completely biodegradable, which brings practicability and further improves the use performance of the product. Importantly, the completely degradable product is environmentally friendly, and will be a major trend in the future development of aqueous polyurethane.

[0106] The product cost is accounted, and the cost of preparing about 600ml (1 Jin) water type polyurethane emulsion is 14.7551 yuan, DMPA, BDO, TEA and acetone are reagent grade MacLaren and Aladdin raw materials, and the price of enterprise raw materials with the same performance in the later stage will be lower, and 20,000 yuan / ton can be realized.

[0107] The application tests three kinds of waterborne polyurethane emulsion by controlling the ratio of soft and hard segments and controlling the acid content.

[0108] In the comparison of the performance of the three formulations: the soft segment content of example 1 is 39.3%; the soft segment content of example 2 is 62.9%; the soft segment content of example 3 is 55.8%. The acid content of example 1 and 8 is controlled at 3.7%, and the acid content of example 3 is controlled at 4%. Compared with the sample with acid content of 4%, the water resistance of the sample with acid content of 3.7% reaches the standard; in terms of stability, the stability of example 1 is better than that of example 2 and example 3.

[0109] Table 1. Water resistance of waterborne polyurethane on paper

[0110]

[0111] Note: The target value of coated paper is Cobb1800 < 10; Kit value ≥ 8

[0112] The coated paper is dried at room temperature.

[0113] 0# is a commercially available coating that does not meet the waterproofing standard when dried at room temperature.

[0114] Table 2. Water resistance effect of coated paper at different temperatures Cobb1800

[0115]

[0116] By integrating and optimizing the above three formulations, formula four (example 4) is designed, and one liter of emulsion is prepared for testing, and the influence of coating amount on the water resistance of paper is discussed (Table 3); the stability safety and water and oil resistance of the emulsion after long-term static are discussed (Tables 4-5), and no toxic monomer of toluene-2, 4(6)-diisocyanate is detected in 0# and example 4 coatings; after 0# and example 4 coatings are stored for 60 days, Cobb1800s and Kit value can meet the requirements; the Cobb1800s and Kit value of the coated paper using 0# and example 4 coatings can meet the requirements after 60 days of storage:

[0117] Table 3. Influence of coating amount on water resistance of paper Cobb1800

[0118]

[0119] Table 4. Waterproof and oil-proof effect after the base paper is stored for 60 days

[0120]

[0121] Table 5. Waterproof and oil-proof effect after the base paper is stored for 60 days

[0122]

[0123] In terms of product performance, the mature product prepared in Example 4 has a viscosity of only 8.6 mpa.s at a solid content of up to 33%, fully meeting the requirements of large-scale preparation of enterprises and normal coating use of products. In terms of stability, the mature product prepared in Example 4 reaches the standard in the stability test. When the product is applied to paper, the Cobb1800s and Kit values can meet the requirements under the condition of a coating amount of 4.64 g / m 2 , and in terms of degradation performance test, the degradation degree reaches 52.6% in a degradation period of 57 days (Table 6), and the hot water and hot oil barrier test on instant noodle bowls (Table 7) is carried out.

[0124] Table 6. Performance characteristics of the mature product

[0125]

[0126] Table 7. Simulation and determination results of instant noodle bowl use conditions

[0127]

[0128] The coated cardboard is soaked in 98℃ hot water and 105℃ hot oil for 30 min, respectively, and both show good barrier properties.

[0129] The tensile strength and tear strength of Examples 5-12 and Comparative Examples 1-3 are tested, and the results are shown in Table 8.

[0130] Table 8. Influence of the compounding ratio of dialdehyde starch, PVA, water-based polyurethane and methacrylic acid resin on the performance of paper

[0131]

[0132]

[0133]

[0134] From Table 1, in Examples 5-8, with the increase of the amount of PVA, the tensile strength and tear strength of the paper gradually increase, and the coating thickness slightly decreases, and when the dialdehyde starch: PVA = 1:1, the overall mechanical properties of the paper are relatively optimal; from the comparison of Example 5 and Example 9, it can be known that the double-layer coating can significantly improve the tear strength of the paper; from the comparison of Example 9, Example 10 and Comparative Example 2, it can be known that the dialdehyde starch-PVA-water-based polyurethane composite coating can significantly improve the tensile strength and tear strength of the paper, the dialdehyde starch-PVA coating reduces the penetration of the polyester emulsion to the paper, improves the internal bonding force of the paper, the water-based polyurethane coating prepared in Example 10 improves the overall mechanical properties of the paper, and the two have synergistic effect; from the comparison of Example 10 and Example 11, it can be known that the performance of the paper coated by multiple layers is greatly improved, the tensile strength can reach 3.49KN / m, which is increased by 71.9% compared with the base paper, and the tear strength is as high as 2573mN, which is increased by 730% compared with the base paper; in Comparative Example 3, the present application also attempts to compound the dialdehyde starch-PVA coating with the methacrylic resin, but the loading effect of the methacrylic resin on the dialdehyde starch-PVA coating is not good, the coating thickness is low, and the mechanical properties are not greatly improved.

[0135] The preferred embodiments of the present application have been described above with the purpose of not limiting the present application, and for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A waterborne polyurethane, characterized in that, include: PCL, DMPA, and BDO were mixed evenly at a mass ratio of 5:0.47:1.995 and reacted to obtain an intermediate product. The intermediate product was then reacted with TDI. After the reaction was completed, TEA was added for neutralization. After the reaction was completed, the mixture was emulsified to obtain waterborne polyurethane. The mass ratio of PCL to TDI and TEA was 5:4.9:0.

355. The structure of the PCL is shown below: 。 2. A waterborne polyurethane, characterized in that, include: PCL, DMPA, and BDO were mixed uniformly at a mass ratio of 84.15:7.65:29.445 and reacted to obtain an intermediate product. The intermediate product was then reacted with TDI. After the reaction was completed, TEA was added for neutralization. After the reaction was completed, the mixture was emulsified to obtain waterborne polyurethane. The mass ratio of PCL to TDI and TEA was 84.15:74.17:5.

771. The structure of the PCL is shown below: 。 3. A high-strength paper-based packaging material, characterized in that, include: base paper; The base paper has at least one layer of dialdehyde starch-PVA loaded on it; The dialdehyde starch-PVA layer is loaded with at least one layer of the waterborne polyurethane layer as described in claim 1 or 2; The dialdehyde starch-PVA layer is composed of the following raw materials in parts by weight: 1-6 parts of dialdehyde starch with a concentration of 25wt%-30wt% and 1-3 parts of PVA with a concentration of 10wt%-12wt%.

4. The high-strength paper-based packaging material as described in claim 3, characterized in that, The dialdehyde starch-PVA layer is provided with 1-3 layers; Alternatively, the waterborne polyurethane layer may be provided in 1-3 layers; Alternatively, the thickness of each wet film layer is 10~50μm.

5. A method for preparing a high-strength paper-based packaging material, characterized in that, include; Mix the dialdehyde starch with water evenly and stir at 60~90℃ for 1~1.5h to obtain gelatinized starch; The gelatinized starch and PVA are mixed evenly to obtain a dialdehyde starch-PVA mixture; The dialdehyde starch-PVA mixture is coated onto the surface of a paper-based material and dried to obtain a base paper loaded with a dialdehyde starch-PVA layer. The aqueous polyurethane of claim 1 or 2 is coated onto the base paper loaded with the dialdehyde starch-PVA layer and dried to obtain the final product.

6. The method for preparing the high-strength paper-based packaging material as described in claim 5, characterized in that, Multiple layers of dialdehyde starch-PVA are then loaded onto the base paper loaded with the dialdehyde starch-PVA layer.

7. The method for preparing the high-strength paper-based packaging material as described in claim 5, characterized in that, A multilayer waterborne polyurethane layer is loaded onto the base paper loaded with a dialdehyde starch-PVA layer.

8. The paper-based packaging material prepared by the method according to any one of claims 5-7.

9. The application of the paper-based packaging material according to claim 8 in the cold chain and daily chemical industries.

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