A highly hydrophobic starch-based straw and preparation method thereof

Abstract

The present invention belongs to the technical field of biodegradable straw development, specifically relating to a highly hydrophobic starch-based straw and its preparation method. By esterifying starch with octenylsuccinic anhydride, the hydrophobic alkenyl chain introduced can improve the hydrophobicity of the starch. The addition of SiO2 can combine with the hydroxyl groups in the starch to form a Si-O-C bond, improving the sensitivity of the octenylsuccinate starch-based straw to moisture. 19 NSi2 reacts with starch molecules to form ‑Si‑O‑C‑bonds, and can also quickly react with SiO2 to form a more stable Si‑O‑Si(CH3)3 structure, grafting the hydrophobic ‑CH3 onto the surface of the octenylsuccinate starch-based straw, further improving the straw's hydrophobic properties.

Description

Technical Field

[0001] The invention belongs to the technical field of development of degradable straws, and in particular relates to a highly hydrophobic starch-based straw and a preparation method thereof. Background Art

[0002] The large amount of waste generated after the use of petroleum-based plastic straws has caused significant negative impacts on the environment on which human beings depend for survival. In January 2020, the National Development and Reform Commission and the Ministry of Ecology and Environment issued the "Opinions on Further Strengthening the Control of Plastic Pollution", which stipulates that by the end of 2020, the use of non-degradable disposable plastic straws will be banned in the catering industry nationwide. Therefore, the development of environmentally friendly biodegradable straws has become a hot topic for researchers. Starch is regarded as one of the most promising natural environmentally friendly polymers because of its renewable and fully degradable nature. However, due to the large number of hydrophilic hydroxyl groups in the starch molecular structure, starch-based straws have problems such as poor hydrophobicity and inability to withstand hot water immersion. In particular, when starch-based straws are used for hot drinks, they easily absorb water and swell, and even gradually dissolve. Summary of the Invention

[0003] In view of the problems of poor hydrophobicity and inability to be soaked in hot water in current powder-based straws, the present invention provides a highly hydrophobic octenylsuccinate starch-based straw and a preparation method thereof. 19 The double hydrophobic modification treatment of NSi2 by steam method is of great significance for developing an environmentally friendly starch-based straw with strong hydrophobic properties and resistance to high temperature immersion.

[0004] The technical solution of this application is as follows:

[0005] A highly hydrophobic starch-based straw comprises the following raw materials in parts by weight: based on corn starch, 2-6% octenylsuccinic anhydride, 3-8% SiO2, 0.008-0.028% NaOH, and 30-35% water.

[0006] Furthermore, it also includes the use of C6H 19 NSi2 steam treatment modification.

[0007] The method for preparing the highly hydrophobic starch-based straw comprises the following steps:

[0008] (1) Mixing of raw materials and auxiliary materials: Mix corn starch, octenylsuccinic anhydride, SiO2 and NaOH dissolved in distilled water, add water, stir and let stand;

[0009] (2) Extrusion construction of highly hydrophobic starch-based straws: the material obtained in step (1) is added into a twin-screw extruder and extruded through a straw forming extrusion die to form a tube embryo;

[0010] (3) Cutting: Cooling the tube embryo obtained in step (2) and then cutting it;

[0011] (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The NSi2 solution was placed in a sealed container in a drying oven using C6H 19 NSi2 vapor is sprayed on the inner and outer surfaces of the straw, and after being evenly sprayed, it is cooled to room temperature to obtain a highly hydrophobic starch-based straw.

[0012] Preferably, the stirring conditions in step (1) are: rotation speed 100-400 rpm, time 5-15 min.

[0013] Preferably, the conditions of the twin-screw extruder in step (2) are: screw speed 60-300 rpm; the temperatures of zones 1 to 4 in the extrusion chamber are 40-50°C, 50-60°C, 80-110°C, and 80-100°C, respectively.

[0014] Preferably, it contains sufficient C6H 19 A baffle with air holes is set in the sealed container of NSi2 solution. The pipette is placed on the baffle to prevent it from contacting with C6H 19 Contact with NSi2 solution.

[0015] Preferably, step (4) C6H 19 The conditions for hydrophobic modification of NSi2 by steam method are: drying oven temperature 45-55℃; treatment time 40-120min.

[0016] Starch undergoes an esterification reaction with octenyl succinic anhydride, and the introduction of long hydrophobic alkenyl chains can improve the hydrophobic properties of starch. Esterification of starch with octenyl succinic anhydride requires disrupting the dense structure of starch granules, increasing the specific surface area, reducing crystallinity, and dispersing the starch molecules, thereby making the octenyl succinic anhydride groups more accessible to the hydroxyl groups within and between starch molecules. Therefore, the extrusion method utilizes high temperature, high pressure, and strong shear forces within the extrusion chamber to disrupt the dense and firmly crystalline regions within the starch granules, formed by hydrogen bonding between molecules on hydroxyl groups, as well as the "shell" structure formed by the fusion of sub-granular "blocklets" on the periphery of the starch granules. This allows more octenyl succinic anhydride to enter the starch granules, promoting the esterification reaction between the octenyl succinic anhydride and the hydroxyl groups within and between starch molecules, thereby increasing the hydrophobicity of the starch by introducing a large number of long hydrophobic alkenyl chains into the starch molecules.

[0017] The added SiO2 can combine with the hydroxyl groups in starch to form -Si-OC- bonds, improving the sensitivity of octenyl succinate starch-based straws to moisture.19 NSi2 reacts with starch molecules to form -Si-OC- bonds, and can also quickly react with SiO2 to form a more stable Si-O-Si(CH3)3 structure, grafting the hydrophobic -CH3 onto the surface of octenylsuccinate starch-based straws, further improving the hydrophobic properties of the straws.

[0018] Beneficial effects of the present invention:

[0019] The hydrophobic alkenyl chain introduced by the esterification reaction between starch and octenyl succinic anhydride can improve the hydrophobic properties of starch; the addition of SiO2 can combine with the hydroxyl groups in starch to form -Si-OC- bonds, thereby improving the sensitivity of octenyl succinate starch-based straws to moisture; C6H 19 NSi2 reacts with starch molecules to form -Si-OC- bonds, and can also quickly react with SiO2 to form a more stable Si-O-Si(CH3)3 structure, grafting the hydrophobic -CH3 onto the surface of octenylsuccinate starch-based straws, further improving the hydrophobic properties of the straws.

[0020] (1) The present invention introduces a long alkenyl chain of a hydrophobic group into the starch molecule through esterification modification to perform the first hydrophobic modification treatment on the straw.

[0021] (2) The present invention uses C6H 19 The NSi2 vapor method grafts hydrophobic -CH3 groups onto the surface of the straw to perform a second hydrophobic modification on the straw.

[0022] (3) The present invention adopts double hydrophobic modification treatment, and the prepared straws have good hydrophobic properties and are resistant to high-temperature immersion. The starch-based straws are environmentally friendly, green and degradable, and can alleviate the white pollution problem caused by petroleum-based plastic straws. DETAILED DESCRIPTION

[0023] For a better understanding of the present invention, the technical solutions of the present invention are further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0024] Example 1

[0025] A method for preparing a highly hydrophobic starch-based straw comprises the following steps:

[0026] (1) Mixing of raw materials and auxiliary materials: Add corn starch, octenylsuccinic anhydride (accounting for 3% of corn starch addition), SiO2 (accounting for 4% of corn starch addition) and NaOH dissolved in distilled water (accounting for 0.013% of corn starch addition) into a high-speed blender and mix well. Add water (accounting for 30% of corn starch addition) from the additive valve and stir at 350 rpm for 10 min. After mixing well, bag and let stand.

[0027] (2) Construction of octenylsuccinate starch-based straw extrusion: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 120 rpm, the temperatures of the first to fourth zones of the extrusion chamber barrel are set to 45°C, 55°C, 100°C, and 90°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0028] (3) Cutting process: The tube blank obtained in step (2) is cooled by a conveying device (with a built-in fan), and then cut by a cutting machine after cooling;

[0029] (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The sealed container of NSi2 solution was placed in a drying oven at 50℃ and heated with C6H 19 NSi2 vapor was sprayed on the inner and outer surfaces of the straw for 100 minutes. After the reaction, the straw was cooled to room temperature to obtain a highly hydrophobic starch-based straw.

[0030] Example 2

[0031] A method for preparing a highly hydrophobic starch-based straw comprises the following steps:

[0032] (1) Mixing of raw materials and auxiliary materials: Add corn starch, octenylsuccinic anhydride (accounting for 2% of corn starch addition), SiO2 (accounting for 8% of corn starch addition) and NaOH dissolved in distilled water (accounting for 0.028% of corn starch addition) into a high-speed blender and mix well. Add water (accounting for 35% of corn starch addition) from the additive valve and stir at 400 rpm for 5 min. After mixing well, bag the mixture and let it stand.

[0033] (2) Construction of octenylsuccinate starch-based straw extrusion: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 90 rpm, the temperature of the first to fourth zones of the extrusion chamber barrel is set to 40°C, 50°C, 80°C, 80°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0034] (3) Cutting process: The tube blank obtained in step (2) is cooled by a conveying device (with a built-in fan), and then cut by a cutting machine after cooling;

[0035] (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The sealed container of NSi2 solution was placed in a drying oven at 52℃ and heated with C6H 19NSi2 vapor was sprayed on the inner and outer surfaces of the straw for 85 min, and then cooled to room temperature after the reaction to obtain a highly hydrophobic starch-based straw.

[0036] Example 3

[0037] A method for preparing a highly hydrophobic starch-based straw comprises the following steps:

[0038] (1) Mixing of raw materials and auxiliary materials: Add corn starch, octenylsuccinic anhydride (accounting for 6% of the amount of corn starch added), SiO2 (accounting for 3% of the amount of corn starch added) and NaOH dissolved in distilled water (accounting for 0.008% of the amount of corn starch added) into a high-speed blender and mix well. Add water (accounting for 32% of the amount of corn starch added) from the additive valve and stir at 100 rpm for 15 min. After mixing well, bag the mixture and let it stand.

[0039] (2) Construction of octenylsuccinate starch-based straw extrusion: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 150 rpm, the temperature of the first to fourth zones of the extrusion chamber barrel is set to 50°C, 60°C, 110°C, and 100°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0040] (3) Cutting process: The tube blank obtained in step (2) is cooled by a conveying device (with a built-in fan), and then cut by a cutting machine after cooling;

[0041] (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The sealed container of NSi2 solution was placed in a drying oven at 52℃ and heated with C6H 19 NSi2 vapor was sprayed on the inner and outer surfaces of the straw for 75 min, and then cooled to room temperature after the reaction to obtain a highly hydrophobic starch-based straw.

[0042] Comparative Example 1

[0043] (1) Mixing of raw materials and auxiliary materials: Add corn starch, SiO2 (accounting for 4% of corn starch addition) and NaOH dissolved in distilled water (accounting for 0.013% of corn starch addition) into a high-speed blender and mix well. Add water (accounting for 30% of corn starch addition) from the additive valve and stir at 350 rpm for 10 min. After mixing well, bag the mixture and let it stand.

[0044] (2) Corn starch-based straw extrusion construction: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 120 rpm, the temperatures of the first to fourth zones of the extrusion chamber barrel are set to 45°C, 55°C, 100°C, and 90°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0045] (3) Cutting process: The tube blank obtained in step (2) is cooled by a conveying device (with a built-in fan), and then cut by a cutting machine after cooling;

[0046] (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The sealed container of NSi2 solution was placed in a drying oven at 50℃ and heated with C6H 19 The inner and outer surfaces of the straw were sprayed with NSi2 vapor for 100 min, and the straw was cooled to room temperature after the reaction to obtain a corn starch-based straw.

[0047] Compared with Example 1, except that octenyl succinic anhydride was not added, the remaining operating steps were the same as those of Example 1.

[0048] Comparative Example 2

[0049] (1) Mixing of raw materials and auxiliary materials: Add corn starch, octenylsuccinic anhydride (accounting for 3% of the amount of corn starch added) and NaOH dissolved in distilled water (accounting for 0.013% of the amount of corn starch added) into a high-speed blender and mix well. Add water (accounting for 30% of the amount of corn starch added) from the additive valve and stir at 350 rpm for 10 min. After mixing well, bag and let stand.

[0050] (2) Construction of octenylsuccinate starch-based straw extrusion: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 120 rpm, the temperatures of the first to fourth zones of the extrusion chamber barrel are set to 45°C, 55°C, 100°C, and 90°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0051] (3) Cutting process: The tube embryo obtained in step (2) is cooled by a conveying device (with a built-in fan), and after cooling, it is cut by a cutting machine to obtain octenyl succinate starch-based straws.

[0052] Compared with Example 1, except that SiO2 was not added and C6H 19 Except for the hydrophobic modification of NSi2 by steam method, the other operating steps are the same as those in Example 1.

[0053] Comparative Example 3

[0054] (1) Mixing of raw materials and auxiliary materials: Add corn starch and NaOH dissolved in distilled water (accounting for 0.013% of the amount of corn starch added) into a high-speed blender and mix well. Add water (accounting for 30% of the amount of corn starch added) from the additive valve and stir at 350 rpm for 10 min. After mixing well, bag the mixture and let it stand.

[0055] (2) Corn starch-based straw extrusion construction: The material obtained in step (1) is evenly added into a twin-screw extruder through a feeder, the screw speed of the extruder is set to 120 rpm, the temperatures of the first to fourth zones of the extrusion chamber barrel are set to 45°C, 55°C, 100°C, and 90°C, and the material is extruded through a straw forming extrusion die to form a tube embryo;

[0056] (3) Cutting process: The tube embryo obtained in step (2) is cooled by a conveying device (with a built-in fan), and after cooling, it is cut by a cutting machine to obtain corn starch-based straws.

[0057] Compared with Example 1, except that octenyl succinic anhydride and SiO2 were not added, and C6H 19 Except for the hydrophobic modification of NSi2 by steam method, the other operating steps are the same as those in Example 1.

[0058] The water absorption rate of the straw samples obtained in Example 1 and Comparative Examples 1-3 was measured:

[0059] Water absorption rate determination method: Weigh the starch-based straw (M1) and soak it in 50°C water for 15 minutes. Take out the starch-based straw and wipe the surface with absorbent paper. Record the weight of the straw after soaking (M2).

[0060]

[0061] Table 1 Water absorption rate of straws prepared in Example 1 and Comparative Examples 1-3

[0062]

[0063] As shown in Table 1, the present invention adopts octenyl succinic anhydride esterification modification and C6H 19 The water absorption rate of the straws prepared after double hydrophobic modification by steaming NSi2 was only 9.2% (Example 1), significantly lower than that of Comparative Examples 1-3, indicating that the straws prepared by this method have good hydrophobicity. When octenyl succinic anhydride is not added, the water absorption rate of the straws increases compared with Example 1 (Comparative Example 1), indicating that the long alkenyl chain hydrophobic group introduced by esterification modification can improve the hydrophobicity of the straws. When C6H 19When NSi2 was hydrophobically modified by steam method, the water absorption rate of the straw increased significantly compared with Example 1 (Comparative Example 2), which shows that the hydrophobic -CH3 group introduced by the Si-O-Si(CH3)3 structure can significantly improve the hydrophobicity of the straw. 19 When the NSi2 was hydrophobically modified by steam, the water absorption rate of the straw was the largest (Comparative Example 3), which indicated that the esterification modification and C6H 19 The double treatment of NSi2 steam modification can effectively improve the hydrophobicity of the straw. The straw prepared by this method has the characteristics of high hydrophobicity and high temperature immersion resistance.

Claims

1. A highly hydrophobic starch-based straw, characterized in that: The method comprises the following raw materials in parts by weight: based on corn starch, 2-6% octenylsuccinic anhydride, 3-8% SiO2, 0.008-0.028% NaOH, and 30-35% water; The preparation method of the highly hydrophobic starch-based straw comprises: (1) Mixing of raw materials and auxiliary materials: Mix corn starch, octenylsuccinic anhydride, SiO2 and NaOH dissolved in distilled water, add water, stir and let stand; (2) Extrusion construction of octenylsuccinate starch-based straws: the material obtained in step (1) is added into a twin-screw extruder and extruded through a straw forming extrusion die to form a tube embryo; (3) Cutting: Cooling the tube embryo obtained in step (2) and then cutting it; (4) C6H 19 Hydrophobic modification of NSi2 by steam method: Place the cut straw from step (3) on a plate containing sufficient C6H 19 The NSi2 solution was placed in a sealed container in a drying oven using C6H 19 NSi2 vapor is sprayed on the inner and outer surfaces of the straw, and after being evenly sprayed, it is cooled to room temperature to obtain a highly hydrophobic starch-based straw.

2. The highly hydrophobic starch-based straw according to claim 1, characterized in that: The stirring conditions in step (1) are: rotation speed 100-400 rpm, time 5-15 min.

3. The highly hydrophobic starch-based straw according to claim 1, characterized in that: The conditions of the twin-screw extruder in step (2) are as follows: screw speed 60-300 rpm; the temperatures of zones 1 to 4 in the extrusion chamber are 40-50°C, 50-60°C, 80-110°C, and 80-100°C, respectively.

4. The highly hydrophobic starch-based straw according to claim 1, characterized in that: Contains sufficient C6H 19 A baffle with air holes is set in the sealed container of NSi2 solution. The pipette is placed on the baffle to prevent it from contacting with C6H 19 Contact with NSi2 solution.

5. The highly hydrophobic starch-based straw according to claim 1, characterized in that: Step (4) C6H 19 The conditions for hydrophobic modification of NSi2 by steam method are: drying oven temperature 45-55℃; treatment time 40-120min.

Images