Biomass-based thermoplastic blended nano composite film and preparation method thereof

Abstract

The invention discloses a biomass-based thermoplastic blended nano composite film and a preparation method thereof. The thermoplastic starch nano composite film comprises 64%-74% of starch and N-methylmorpholine-N-oxide, 25%-35% of a biodegradable synthetic polymer and 0%-6% of an inorganic nano material, wherein the total amount of the starch and N-methylmorpholine-N-oxide is 64%-74%. The inorganic nano material can be one or more of nano calcium carbonate, nano montmorillonite, nano silicon dioxide, carbon nanotubes or graphene. The mass ratio of the starch to the N-methylmorpholine-N-oxide is preferably (7: 3)-(2: 1). The melting point of the biodegradable synthetic polymer needs to be less than or equal to 140 DEG C. According to the preparation method, a melt blending compounding method and a melt thermoplastic blow molding method are adopted, the melt blending temperature needs to be smaller than or equal to 140 DEG C, and the thermoplastic blow molding temperature needs to be smaller than or equal to 140 DEG C. The biomass-based thermoplastic blended nano-composite film is biodegradable and excellent in mechanical property, and the preparation method is simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to a biodegradable thermoplastic film and a preparation method thereof, and particularly to a thermoplastic starch nanocomposite film and a preparation method thereof, belonging to the field of biodegradable polymer products. Background Art

[0002] Currently, most of the film materials such as food packaging, agricultural films, and mulch films used are made of petroleum-based high molecular compounds such as polyethylene, polypropylene, and polyvinyl chloride. Even though they have good properties, they are difficult to degrade in the environment and will cause great pollution to the environment after use. Therefore, the development of biodegradable plastic films is the current mainstream research direction. Among them, starch, as the biomass material with the highest global production capacity, can be completely degraded by the environment and can be used in the research of biodegradable materials. However, the pure thermoplastic starch material prepared from starch has poor properties and cannot be directly used in real life. The relatively maturely studied biodegradable plastics (PBAT, PLA, PCL, etc.) have good properties and can be used in fields such as food packaging, but their preparation processes are complex and strict, and the cost is high. Therefore, adding a small amount of costly biodegradable plastics to the matrix of thermoplastic starch can enhance the properties of thermoplastic starch and the cost is relatively low. Adding a small amount of nano-inorganic fillers to the system can, to a certain extent, enhance the mechanical properties, thermal stability, flame retardancy, and rheological properties of TPS, etc. In addition, most nano-inorganic fillers are hydrophilic and can be evenly dispersed in the starch matrix, playing a role in filling the voids at the TPS / PBAT interface, thereby enhancing the compatibility of the composite material. The thermoplastic starch nanocomposite film prepared by this method can have good properties and low cost while taking into account biodegradability. Summary of the Invention

[0003] The purpose of the present invention is to provide a thermoplastic starch nanocomposite film that is biodegradable, has excellent mechanical properties, and has a simple and easy preparation method, as well as a preparation method thereof.

[0004] The technical solution for achieving the purpose of the present invention is: a thermoplastic starch nanocomposite film, containing 64% - 74% in total of starch and N-methylmorpholine-N-oxide, 25% - 35% of a biodegradable synthetic polymer, and 0% - 6% of an inorganic nano material.

[0005] In the thermoplastic starch nanocomposite film of the present invention, the inorganic nano material is one or more of nano calcium carbonate, nano montmorillonite, nano silicon dioxide, carbon nanotubes, or graphene.

[0006] In the thermoplastic starch nanocomposite film of the present invention, the mass ratio of starch to N-methylmorpholine-N-oxide is preferably 7:3 - 2:1.

[0007] In the thermoplastic starch nanocomposite film of the present invention, the melting point of the biodegradable synthetic polymer must be ≤ 140 °C.

[0008] The thermoplastic starch nanocomposite film of the present invention is formed by thermoplastic blow molding.

[0009] The preparation method of the thermoplastic starch nanocomposite film of the present invention successively includes the following steps:

[0010] (1) Mix starch, nano-inorganic filler and N-methylmorpholine-N-oxide liquid;

[0011] (2) Use a twin-screw extruder for melt mixing and extrude thermoplastic starch;

[0012] (3) Melt blend and extrude the thermoplastic starch and the biodegradable synthetic polymer to obtain a thermoplastic starch nanocomposite;

[0013] (4) Use a blown film machine to perform thermoplastic blow molding on the thermoplastic starch nanocomposite to form a film product.

[0014] The preparation method of the thermoplastic starch nanocomposite film of the present invention may also successively include the following steps:

[0015] (1) Mix starch, nano-inorganic particles and N-methylmorpholine-N-oxide liquid;

[0016] (2) Solid-state mix the aforementioned mixture with biodegradable synthetic polymer particles;

[0017] (3) Use a screw extruder for melt blending and extrusion to form a thermoplastic starch nanocomposite;

[0018] (4) Use a blown film machine to perform thermoplastic blow molding on the thermoplastic starch nanocomposite to form a film product.

[0019] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid must be ≥ 75%.

[0020] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the melting point of the biodegradable synthetic polymer used must be ≤ 140 °C.

[0021] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the melt blending temperature of the screw extruder must be ≤ 140 °C, and the thermoplastic blow molding temperature must be ≤ 140 °C.

[0022] The thermoplastic starch nanocomposite film of the present invention and its preparation method have the following remarkable advantages: (1) The N-methylmorpholine-N-oxide used in the present invention is environmentally friendly. The thermoplastic starch nanocomposite film of the present invention is completely biodegradable, has excellent mechanical properties, and low cost; (2) Adding nano-inorganic particles to the thermoplastic starch nanocomposite film of the present invention can improve the mechanical properties, thermal stability and hydrophobic properties of thermoformed products; (3) The preparation method of the thermoplastic starch nanocomposite film of the present invention is simple and easy to implement, can be used for thermoformed products, and the forming method is simple and the cost is low. Detailed implementation mode

[0023] The thermoplastic starch nanocomposite film of the present invention contains 64% - 74% of the total amount of starch and N-methylmorpholine-N-oxide, 25% - 35% of biodegradable synthetic polymer, and 0% - 6% of inorganic nanomaterials.

[0024] The starch in the thermoplastic starch nanocomposite film of the present invention refers to plant materials mainly composed of starch in organic components, which can be one or more of rice, wheat, corn, sorghum, and tubers. Tubers can be potatoes, sweet potatoes, cassava, etc. The term "one or more" as used herein means two or more.

[0025] In the thermoplastic starch nanocomposite film of the present invention, the inorganic nanomaterials are one or more of nano calcium carbonate, nano montmorillonite, nano silicon dioxide, carbon nanotubes or graphene.

[0026] In the thermoplastic starch nanocomposite film of the present invention, the mass ratio of starch to N-methylmorpholine-N-oxide is preferably 7:3 - 2:1. In the thermoplastic starch nanocomposite film of the present invention, a starch plasticizer with a content lower than 1 / 3 of the mass of N-methylmorpholine-N-oxide can be contained, and the starch plasticizer can be glycerol, triethanolamine, sorbitol, etc.

[0027] In the thermoplastic starch nanocomposite film of the present invention, the melting point of the biodegradable synthetic polymer must be ≤ 140°C. The biodegradable synthetic polymer can be polybutylene adipate-co-terephthalate, polybutylene succinate, polycaprolactone, etc.

[0028] The thermoplastic starch nanocomposite film of the present invention is formed by thermoplastic blow molding.

[0029] The preparation method of the thermoplastic starch nanocomposite film of the present invention sequentially includes the following steps:

[0030] (1) Mix starch, nano-inorganic filler and N-methylmorpholine-N-oxide liquid;

[0031] (2) Use a twin-screw extruder for melt mixing to extrude thermoplastic starch;

[0032] (3) The thermoplastic starch is melt-blended and extruded with a biodegradable synthetic polymer to obtain a thermoplastic starch nanocomposite;

[0033] (4) The thermoplastic starch nanocomposite is thermoplastic blow-molded into a film product using a film blowing machine.

[0034] The preparation method of the thermoplastic starch nanocomposite film of the present invention may also sequentially include the following steps:

[0035] (1) Mix starch, nano-inorganic particles and N-methylmorpholine-N-oxide liquid;

[0036] (2) Solid-state mix the aforementioned mixture with biodegradable synthetic polymer particles;

[0037] (3) Melt-blend and extrude using a screw extruder to become a thermoplastic starch nanocomposite;

[0038] (4) The thermoplastic starch nanocomposite is thermoplastic blow-molded into a film product using a film blowing machine.

[0039] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid must be ≥ 75%. The content of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide liquid is preferably ≥ 80%. For example, the N-methylmorpholine-N-oxide liquid is N-methylmorpholine-N-oxide monohydrate. The N-methylmorpholine-N-oxide liquid may contain a starch plasticizer less than 1 / 3 of the mass of N-methylmorpholine-N-oxide, and the starch plasticizer such as glycerol, triethanolamine, sorbitol, etc.

[0040] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the melting point of the biodegradable synthetic polymer used must be ≤ 140°C.

[0041] In the preparation method of the thermoplastic starch nanocomposite film of the present invention, the melt-blending temperature of the screw extruder must be ≤ 140°C, preferably 100 - 130°C. The thermoplastic blow-molding temperature must be ≤ 140°C, preferably 100 - 130°C.

[0042] Example 1

[0043] Mix 235 g of starch, 10 g of nano calcium carbonate, 10105 g of antioxidant with 105 g of N-methylmorpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, and send it to a pelletizer for pelletizing after cooling with cold air to obtain thermoplastic starch. Mix it with 150 g of polybutylene terephthalate-adipate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain the thermoplastic starch nanocomposite of the present invention. Use a blown film machine to thermoplastically blow mold at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 4.12 MPa, and the elongation at break is 175%.

[0044] Example 2

[0045] Mix 225 g of starch, 20 g of nano calcium carbonate, 10105 g of antioxidant with 105 g of N-methylmorpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, and send it to a pelletizer for pelletizing after cooling with cold air to obtain thermoplastic starch. Mix it with 150 g of polybutylene terephthalate-adipate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain the thermoplastic starch nanocomposite of the present invention. Use a blown film machine to thermoplastically blow mold at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 4.66 MPa, and the elongation at break is 118%.

[0046] Example 3

[0047] Mix 215 g of starch, 30 g of nano calcium carbonate, 10105 g of antioxidant with 105 g of N-methylmorpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, and send it to a pelletizer for pelletizing after cooling with cold air to obtain thermoplastic starch. Mix it with 150 g of polybutylene terephthalate-adipate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain the thermoplastic starch nanocomposite of the present invention. Use a blown film machine to thermoplastically blow mold at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 6.83 MPa, and the elongation at break is 23%.

[0048] Example 4

[0049] Mix 235 g of starch, 10 g of nano-montmorillonite, 5 g of antioxidant 1010 with 105 g of N-methyl morpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, cool it with cold air and then send it to a pelletizer for pelletizing to obtain thermoplastic starch. Mix it with 150 g of polybutylene adipate terephthalate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, cool it with cold air and then send it to a pelletizer for pelletizing to obtain the thermoplastic starch nano-composite of the present invention. Use a blown film machine to carry out thermoplastic blow molding at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 4.81 MPa, and the elongation at break is 55%.

[0050] Example 5

[0051] Mix 235 g of starch, 10 g of nano-silica, 5 g of antioxidant 1010 with 105 g of N-methyl morpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, cool it with cold air and then send it to a pelletizer for pelletizing to obtain thermoplastic starch. Mix it with 150 g of polybutylene adipate terephthalate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, cool it with cold air and then send it to a pelletizer for pelletizing to obtain the thermoplastic starch nano-composite of the present invention. Use a blown film machine to carry out thermoplastic blow molding at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 7.9 MPa, and the elongation at break is 149%.

[0052] Example 6

[0053] Mix 235 g of starch, 10 g of carbon nanotubes, 5 g of antioxidant 1010 with 105 g of N-methyl morpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then extrude the material through a twin-screw extruder at 120 °C for melt blending and extrusion, cool it with cold air and then send it to a pelletizer for pelletizing to obtain thermoplastic starch. Mix it with 150 g of polybutylene adipate terephthalate, carry out secondary melt blending and extrusion through a twin-screw extruder at 120 °C, cool it with cold air and then send it to a pelletizer for pelletizing to obtain the thermoplastic starch nano-composite of the present invention. Use a blown film machine to carry out thermoplastic blow molding at 120 °C to obtain a film sample, and the tensile strength after constant temperature and humidity for 24 hours at 23 °C and 50% relative humidity is 7.4 MPa, and the elongation at break is 22%.

[0054] Comparative Example 1

[0055] Mix 245 g of starch, 5 g of antioxidant 1010 with 105 g of N-methyl morpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then melt-blend and extrude the material through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain thermoplastic starch. Mix it with 150 g of polybutylene adipate terephthalate, carry out secondary melt-blending and extrusion through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain a thermoplastic starch blend material for the comparative example. Use a blown film machine to carry out thermoplastic blow molding at 120 °C to obtain a film sample, and the tensile strength after being kept at a constant temperature and humidity at 23 °C and 50% relative humidity for 24 hours is 4.44 MPa, and the elongation at break is 115%.

[0056] Comparative Example 2

[0057] Mix 245 g of starch, 150 g of polybutylene adipate terephthalate, 5 g of antioxidant 1010 with 105 g of N-methyl morpholine-N-oxide hydrate containing 13% water and 10% glycerol, carry out pre-plasticization at 100 °C, then melt-blend and extrude the material through a twin-screw extruder at 120 °C, and send it to a pelletizer for pelletizing after cooling with cold air to obtain a thermoplastic starch blend material for the comparative example. Use a blown film machine to carry out thermoplastic blow molding at 120 °C to obtain a film sample, and the tensile strength after being kept at a constant temperature and humidity at 23 °C and 50% relative humidity for 24 hours is 3.47 MPa, and the elongation at break is 712%.

Claims

1. A thermoplastic starch nanocomposite film, characterized in that: The total amount of starch and N-methyl morpholine-N-oxide is 64% - 74%, the biodegradable synthetic polymer is 25% - 35%, and the inorganic nanomaterial is 0% - 6%.

2. The thermoplastic starch nanocomposite film according to claim 1, wherein: The inorganic nanomaterial is one or more of nano calcium carbonate, nano montmorillonite, nano silica, carbon nanotubes or graphene.

3. The thermoplastic starch nanocomposite film according to any one of claims 1 or 2, characterized in that: The mass ratio of starch to N-methyl morpholine-N-oxide is 7:3 - 2:

1.

4. The thermoplastic starch nanocomposite film according to any one of claims 1 to 3, characterized in that: The melting point of the biodegradable synthetic polymer ≤ 140 °C.

5. The thermoplastic starch nanocomposite film according to any one of claims 1 to 4, characterized in that: Thermoplastic blow molding is adopted.

6. The preparation method of the thermoplastic starch nanocomposite film according to any one of claims 1 to 5, characterized in that: It sequentially includes the following steps: (1) Mix starch, nano inorganic filler and N-methyl morpholine-N-oxide liquid; (2) Adopt a twin-screw extruder for melt mixing and extrude thermoplastic starch; (3) Melt blend and extrude the thermoplastic starch and the biodegradable synthetic polymer to obtain a thermoplastic starch nanocomposite; (4) Use a blown film machine to conduct thermoplastic blow molding on the thermoplastic starch nanocomposite to form a film product.

7. The preparation method of the thermoplastic starch nanocomposite film according to any one of claims 1 to 6, characterized in that: It sequentially includes the following steps: (1) Mix starch, nano inorganic particles and N-methyl morpholine-N-oxide liquid; (2) Solid-state mix the aforementioned mixture with the biodegradable synthetic polymer particles; (3) Adopt a screw extruder for melt blending and extrusion to become a thermoplastic starch nanocomposite; (4) Use a blown film machine to conduct thermoplastic blow molding on the thermoplastic starch nanocomposite to form a film product.

8. The preparation method of the thermoplastic starch nanocomposite film according to claim 6 or 7, characterized in that: The content of N-methyl morpholine-N-oxide in the N-methyl morpholine-N-oxide liquid ≥ 75%.

9. The preparation method of the thermoplastic starch nanocomposite film according to claim 6 or 7, characterized in that: The melting point of the biodegradable synthetic polymer ≤ 140 °C.

10. The preparation method of the thermoplastic starch nanocomposite film according to any one of claims 6 to 9, characterized in that: The melt blending temperature of the screw extruder ≤ 140 °C, and the thermoplastic blow molding temperature ≤ 140 °C.