A starch-based degradable packaging material and a method for preparing the same

Abstract

The present application relates to the technical field of packaging material, and proposes a starch-based degradable packaging material and a preparation method thereof.The starch-based degradable packaging material comprises the following components by weight: modified starch 40-50 parts, polylactic acid 70-80 parts, polycaprolactone 30-40 parts, plasticizer 4-8 parts, and compatibilizer 4-5 parts.The modified starch is obtained by treating starch with amylase and then modifying the treated starch with a modifier.The modifier comprises 3-aminopropyl triethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane.Through the above technical solution, the problem of low mechanical strength of the starch-based degradable packaging material in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a starch-based biodegradable packaging material and its preparation method. Background Technology

[0002] With the rapid development of the packaging industry, the demand for packaging materials has been increasing year by year. Among them, plastic packaging has long dominated the market due to its low cost, good processability, and excellent barrier properties. However, traditional petroleum-based plastics (such as polyethylene and polypropylene) are difficult to degrade in the natural environment, and their waste accumulates in large quantities, forming "white pollution." This not only occupies land resources and pollutes soil and water bodies, but also harms ecosystems and human health through the food chain. Therefore, developing biodegradable alternative materials has become the core direction for solving this problem.

[0003] Currently, among the biodegradable packaging materials available in the industry, starch is considered an ideal raw material to replace petroleum-based plastics because it is a widely available and inexpensive natural polymer. However, pure starch materials have significantly low mechanical strength at certain temperatures, making it difficult to meet the requirements for packaging materials.

[0004] In the current technology, in order to improve the performance of starch-based materials, they are often blended with PCL to achieve complementary properties. However, the compatibility between different materials is poor, and phase separation is prone to occur, which affects the overall performance stability of the material and results in the mechanical strength not being improved well. Summary of the Invention

[0005] This invention proposes a starch-based biodegradable packaging material and its preparation method, which solves the problem of low mechanical strength of starch-based biodegradable packaging materials in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] This invention proposes a starch-based biodegradable packaging material comprising the following raw materials in parts by weight: 40-50 parts modified starch, 70-80 parts polylactic acid, 30-40 parts polycaprolactone, 4-8 parts plasticizer, and 4-5 parts compatibilizer; wherein the modified starch is obtained by treating starch with amylase and then modifying it with a modifier, wherein the modifier includes 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane.

[0008] As a further technical solution, the mass ratio of 3-aminopropyltriethoxysilane to 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 6:2~3.

[0009] As a further technical solution, the mass ratio of 3-aminopropyltriethoxysilane to 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 6:2.5.

[0010] As a further technical solution, the amount of the modifier added is 8% to 10% of the starch mass, for example, it can be 8%, 8.5%, 9%, 9.5%, or 10%.

[0011] As a further technical solution, the preparation method of the modified starch includes the following steps: adding starch and α-amylase to water and mixing at 70~80℃ for 2~3h, then adding a modifier and continuing to mix at 70~80℃ for 0.5~1h, drying, grinding, and sieving to obtain modified starch.

[0012] As a further technical solution, the mass ratio of starch, α-amylase, and water is 1:0.08:25~30.

[0013] As a further technical solution, the compatibilizer includes maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate.

[0014] The compatibilizers in the raw materials of the starch-based biodegradable packaging material of this invention include maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate. The addition of these two ingredients can further improve the density of the starch-based biodegradable packaging material and enhance its barrier properties against water vapor. When applied to food preservation packaging, it can further extend the shelf life of food. When used during food transportation, it can also reduce transportation losses and resource waste.

[0015] As a further technical solution, the mass ratio of maleic anhydride-grafted polypropylene to phenyl 2-aminobenzenesulfonate is 2:1~2.

[0016] As a further technical solution, the mass ratio of maleic anhydride-grafted polypropylene to phenyl 2-aminobenzenesulfonate is 2:1.5.

[0017] As a further technical solution, the starch includes one or more of corn starch, tapioca starch, and potato starch.

[0018] As a further technical solution, the plasticizer includes one or both of dimethyl phthalate and dioctyl phthalate.

[0019] The present invention also proposes a method for preparing starch-based biodegradable packaging material, which includes the following steps: melting and extruding the raw material to obtain starch-based biodegradable packaging material.

[0020] The working principle and beneficial effects of this invention are as follows:

[0021] This invention incorporates starch modified with 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, thereby improving the mechanical strength of starch-based biodegradable packaging materials. The silane-modified starch and PCL complement each other, achieving complementary properties and solving the problem of low mechanical strength in pure starch materials, which fails to meet the requirements of packaging materials, thus improving the overall mechanical strength of the material. 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] In the following embodiments and comparative examples:

[0024] Starch: Corn starch, model 01, manufactured by Jinan Shenglong Chemical Co., Ltd.

[0025] α-Amylase: 2000u / g, Shandong Bisheng Biotechnology Co., Ltd.;

[0026] Polylactic acid: Model 4023D, manufactured by NatureWorks, USA;

[0027] Polycaprolactone: Product No. 6506, Manufacturer: Solvay, USA;

[0028] Maleic anhydride-grafted polypropylene, model 820, manufactured by Dongguan Kangjin New Material Technology Co., Ltd.

[0029] Example 1

[0030] The raw materials for starch-based biodegradable packaging materials include the following components in parts by weight: 40 parts modified starch, 70 parts polylactic acid, 30 parts polycaprolactone, 4 parts dimethyl phthalate, and 4 parts compatibilizer; the compatibilizer is maleic anhydride-grafted polypropylene.

[0031] The method for preparing modified starch includes the following steps: adding starch and α-amylase to water, mixing at 75°C for 2.5 hours, adding a modifier, continuing to mix at 75°C for 0.5 hours, drying, grinding, and passing through an 80-mesh sieve to obtain modified starch; the modifier is composed of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in a mass ratio of 6:2; the mass ratio of starch, α-amylase, and water is 1:0.1:25; the total mass of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 8% of the starch mass;

[0032] A method for preparing a starch-based biodegradable packaging material includes the following steps: mixing the above raw materials evenly and then melting and extruding them through a twin-screw extruder to obtain the starch-based biodegradable packaging material.

[0033] Example 2

[0034] The raw materials for starch-based biodegradable packaging materials include the following components in parts by weight: 45 parts modified starch, 75 parts polylactic acid, 35 parts polycaprolactone, 6 parts dimethyl phthalate, and 4.5 parts compatibilizer; the compatibilizer is maleic anhydride-grafted polypropylene.

[0035] The method for preparing modified starch includes the following steps: adding starch and α-amylase to water, mixing at 75°C for 2.5 hours, adding a modifier, continuing to mix at 75°C for 0.5 hours, drying, grinding, and passing through an 80-mesh sieve to obtain modified starch; the modifier is composed of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in a mass ratio of 6:2; the mass ratio of starch, α-amylase, and water is 1:0.08:25; the total mass of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 8% of the starch mass;

[0036] A method for preparing a starch-based biodegradable packaging material includes the following steps: mixing the above raw materials evenly and then melting and extruding them through a twin-screw extruder to obtain the starch-based biodegradable packaging material.

[0037] Example 3

[0038] The raw materials for starch-based biodegradable packaging materials include the following components in parts by weight: 50 parts modified starch, 80 parts polylactic acid, 40 parts polycaprolactone, 8 parts dimethyl phthalate, and 5 parts compatibilizer; the compatibilizer is anhydride-grafted polypropylene.

[0039] The method for preparing modified starch includes the following steps: adding starch and α-amylase to water, mixing at 75°C for 2.5 hours, adding a modifier, continuing to mix at 75°C for 0.5 hours, drying, grinding, and passing through an 80-mesh sieve to obtain modified starch; the modifier is composed of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in a mass ratio of 6:2; the mass ratio of starch, α-amylase, and water is 1:0.08:15; the total mass of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 8% of the starch mass;

[0040] A method for preparing a starch-based biodegradable packaging material includes the following steps: mixing the above raw materials evenly and then melting and extruding them through a twin-screw extruder to obtain the starch-based biodegradable packaging material.

[0041] Example 4

[0042] Compared with Example 1, the only difference in this example is that the modifier is composed of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in a mass ratio of 6:2.5.

[0043] Example 5

[0044] Compared with Example 1, the only difference in this example is that the modifier is composed of 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in a mass ratio of 6:3.

[0045] Example 6

[0046] Compared with Example 1, the only difference in this example is that the compatibilizer is phenyl 2-aminobenzenesulfonate.

[0047] Example 7

[0048] Compared with Example 1, the only difference in this example is that the compatibilizer is composed of maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate in a mass ratio of 2:1.

[0049] Example 8

[0050] Compared with Example 1, the only difference in this example is that the compatibilizer is composed of maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate in a mass ratio of 2:1.5.

[0051] Example 9

[0052] Compared with Example 1, the only difference in this example is that the compatibilizer is composed of maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate in a mass ratio of 1:1.

[0053] Comparative Example 1

[0054] Compared with Example 1, the only difference in this comparative example is that the modifier is only 3-aminopropyltriethoxysilane.

[0055] Comparative Example 2

[0056] Compared with Example 1, the only difference in this comparative example is that the modifier is only 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane.

[0057] Comparative Example 3

[0058] Compared with Example 1, the only difference in this comparative example is that the modified starch is replaced with an equal amount of starch.

[0059] The properties of the starch-based biodegradable packaging materials in Examples 1-9 and Comparative Examples 1-3 were determined using the following methods:

[0060] (1) Mechanical strength: The tensile strength of starch-based biodegradable packaging materials was determined according to the test method in GB / T 1040.3-2006 "Test of tensile properties of plastics - Part 3: Test conditions for films and sheets". During the test, the sample type was type 2 and the tensile test rate was 200 mm / min. The test results are shown in Table 1.

[0061] Table 1. Results of Mechanical Strength Measurement of Starch-Based Biodegradable Packaging Materials

[0062]

[0063] As shown in Table 1, the tensile strength of the starch-based biodegradable packaging materials in Examples 1-5 is higher than that in Comparative Examples 1-3, indicating that the modification of starch with 3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane in this invention can improve the tensile strength of starch-based biodegradable packaging materials.

[0064] (2) Water vapor transmission rate: The water vapor transmission rate was tested using the permeation cup weighing method. Specifically, the starch-based biodegradable packaging material was weighed every 12 hours under an experimental environment of room temperature and 90% humidity. After the mass change stabilized, the water vapor transmission rate was calculated using the following formula:

[0065] Water vapor transmission rate (g / m) 2 / d)=△W / (t*A;

[0066] Where: △W is the mass difference, in g; t is time, in d (days); A is the permeable area of ​​the thin film, in m². 2 ;

[0067] The measurement results are shown in Table 2.

[0068] Table 2. Results of water vapor transmission rate measurement of starch-based biodegradable packaging materials

[0069]

[0070] As shown in Table 1, the water vapor permeability of Examples 7-9 is lower than that of Examples 1 and 6, indicating that the compatibilizer composed of maleic anhydride-grafted polypropylene and phenyl 2-aminobenzenesulfonate can improve the water vapor barrier properties of starch-based biodegradable packaging materials.

[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A starch-based degradable packaging material, characterized in that, The raw material comprises the following components in parts by weight: modified starch 40-50 parts, polylactic acid 70-80 parts, polycaprolactone 30-40 parts, plasticizer 4-8 parts, and compatibilizer 4-5 parts; the modified starch is obtained by treating starch with amylase and then modifying the treated starch with a modifying agent, wherein the modifying agent comprises 3-aminopropyl triethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane; and the mass ratio of the 3-aminopropyl triethoxysilane to the 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 6:2-3.

2. A starch-based degradable packaging material according to claim 1, characterized in that, The modifying agent is added in an amount of 8-10% of the mass of the starch.

3. A starch-based degradable packaging material according to claim 1, characterized in that, The method for preparing the modified starch comprises the following steps: adding starch and alpha-amylase into water, mixing at 70-80°C for 2-3 hours, adding the modifying agent, and then mixing at 70-80°C for 0.5-1 hour, drying, grinding, sieving, and obtaining the modified starch.

4. A starch-based degradable packaging material according to claim 3, characterized in that, The mass ratio of the starch, the alpha-amylase, and the water is 1:0.08:25-30.

5. A starch-based degradable packaging material according to claim 1, characterized in that, The compatibilizer comprises maleic anhydride grafted polypropylene and 2-aminobenzenesulfonic acid phenyl ester.

6. A starch-based degradable packaging material according to claim 5, characterized in that, The mass ratio of the maleic anhydride grafted polypropylene to the 2-aminobenzenesulfonic acid phenyl ester is 2:1-2.

7. A starch-based degradable packaging material according to claim 1, characterized in that, The starch comprises one or more of corn starch, cassava starch, and potato starch.

8. A starch-based degradable packaging material according to claim 1, characterized in that, The plasticizer comprises one or both of dimethyl phthalate and dioctyl phthalate.

9. A method for producing a starch-based degradable packaging material, for producing a starch-based degradable packaging material according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: After the raw material is melt-extruded, a starch-based degradable packaging material is obtained. The raw material comprises the following components in parts by weight: modified starch 40-50 parts, polylactic acid 70-80 parts, polycaprolactone 30-40 parts, plasticizer 4-8 parts, and compatibilizer 4-5 parts; the modified starch is obtained by treating starch with amylase and then modifying the treated starch with a modifying agent, wherein the modifying agent comprises 3-aminopropyl triethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane; and the mass ratio of the 3-aminopropyl triethoxysilane to the 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is 6:2-3. The modifying agent is added in an amount of 8-10% of the mass of the starch. The method for preparing the modified starch comprises the following steps: adding starch and alpha-amylase into water, mixing at 70-80°C for 2-3 hours, adding the modifying agent, and then mixing at 70-80°C for 0.5-1 hour, drying, grinding, sieving, and obtaining the modified starch. The mass ratio of the starch, the alpha-amylase, and the water is 1:0.08:25-30. The compatibilizer comprises maleic anhydride grafted polypropylene and 2-aminobenzenesulfonic acid phenyl ester. The mass ratio of the maleic anhydride grafted polypropylene to the 2-aminobenzenesulfonic acid phenyl ester is 2:1-2. The starch comprises one or more of corn starch, cassava starch, and potato starch. The plasticizer comprises one or both of dimethyl phthalate and dioctyl phthalate. The method comprises the following steps: After the raw material is melt-extruded, a starch-based degradable packaging material is obtained.

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