High-compatibility starch-based biodegradable plastic and preparation method thereof

Abstract

The invention discloses a high-compatibility starch-based biodegradable plastic and a preparation method of the high-compatibility starch-based biodegradable plastic. The degradable plastic comprises the following raw materials: 50 to 70 parts of thermoplastic starch, 30 to 60 parts of polylactic acid, 10 to 40 parts of PBAT and / or PBS, 0.5 to 10 parts of acetyl tributyl citrate, 5 to 15 parts of a plasticizer, 3 to 10 parts of a flexibilizer, 0.5 to 10 parts of polyethylene glycol, 2 to 10 parts of a compatilizer auxiliary agent, 1 to 3 parts of a degradation accelerator, 0.3 to 2 parts of a lubricant, 0.5 to 3 parts of a hydrolysis assistant, 0.5 to 2 parts of a grafting connecting agent, 2 to 15 parts of an inorganic filler, 3 to 8 parts of a compatibilizer and 0.05 to 0.5 part of an antioxidant. And 0.5 to 10 parts of a nano filler. The method has the advantages that the comprehensive mechanical property of the material is improved, the application range of the material is widened, the thermal stability of the material is improved, and the rigidity and dimensional stability of the material are improved.

Description

Technical Field

[0001] This invention relates to the field of plastic preparation technology, and more particularly to the preparation technology of highly compatible starch-based biodegradable plastics. Background Technology

[0002] The white pollution caused by traditional petroleum-based plastics has attracted widespread public attention, and biodegradable plastics have become an important research direction for solving this problem. Starch, as a widely available, inexpensive, and fully biodegradable natural polymer material, has enormous application potential in the field of biodegradable plastics. However, virgin starch has defects such as poor processing flowability and insufficient mechanical properties, and usually needs to be plasticized to prepare thermoplastic starch (TPS) to overcome the defects of virgin starch.

[0003] Polylactic acid (PLA) is a biodegradable polymer with good mechanical and processing properties, but it suffers from brittleness and low impact strength. Polybutylene adipate / polybutylene terephthalate (PBAT) or polybutylene succinate (PBS) exhibit excellent flexibility and impact toughness, but their tensile strength is relatively low. Blending TPS with PLA, PBAT, and / or PBS can achieve complementary properties, resulting in biodegradable composite materials with excellent overall performance.

[0004] However, TPS is a polar polymer, while PLA and PBAT / PBS are weakly polar or non-polar polymers. The compatibility among these three is poor, and phase separation easily occurs in blends, leading to a decline in the mechanical and processing properties of the materials. Current technologies typically improve compatibility by adding compatibilizers, but the effect of a single compatibilizer is limited and cannot meet the comprehensive performance requirements of practical applications. Furthermore, existing starch-based biodegradable composite materials also suffer from poor controllability of degradation rates, easy starch aging during processing, and uneven dispersion of additives, limiting their large-scale application.

[0005] Therefore, developing a highly compatible starch-based biodegradable plastic with good compatibility, excellent comprehensive mechanical properties, controllable degradation rate, and stable processing performance has important practical significance and application value. Summary of the Invention

[0006] The purpose of this invention is to provide a highly compatible starch-based biodegradable plastic and its preparation method, so as to solve the problems of pollution caused by the difficulty in degrading plastics and the inability to guarantee the quality of easily degradable plastics in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A highly compatible starch-based biodegradable plastic, comprising, by weight, the following raw materials: 50-70 parts thermoplastic starch, 30-60 parts polylactic acid, 10-40 parts PBAT and / or PBS, 0.5-10 parts tributyl acetylacetate, 5-15 parts plasticizer, 3-10 parts toughening agent, 0.5-10 parts polyethylene glycol, 2-10 parts compatibilizer / auxiliary agent, 1-3 parts degradation promoter, 0.3-2 parts lubricant, 0.5-3 parts hydrolysis aid, 0.5-2 parts grafting agent, 2-15 parts inorganic filler, 3-8 parts compatibilizer, 0.05-0.5 parts antioxidant, and 0.5-10 parts nanofiller.

[0009] Furthermore, the thermoplastic starch is obtained by plasticizing starch with glycerol, and the mass ratio of starch to glycerol is 8:2-9:1; the inorganic filler is calcium carbonate and talc, and the mass ratio of calcium carbonate to talc is 1:1.

[0010] Furthermore, the polylactic acid has a weight-average molecular weight of 80,000-150,000; the PBAT has a weight-average molecular weight of 50,000-100,000; and the PBS has a weight-average molecular weight of 60,000-120,000.

[0011] Furthermore, the plasticizer refers to plasticizer products manufactured by BASF AG of Germany, and the toughening agent is ethylene-vinyl acetate copolymer or acrylonitrile-butadiene-styrene copolymer.

[0012] Furthermore, the compatibilizer is maleic anhydride-grafted polyethylene; the compatibilizer is propylene oxide-ethylene oxide copolymer.

[0013] Furthermore, the degradation promoter is oxalic acid or citric acid; the hydrolysis aid is adipic acid.

[0014] Furthermore, the grafting agent is diphenylmethane diisocyanate (MDI); the lubricant is zinc stearate.

[0015] Furthermore, the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the nanofiller is nano-montmorillonite or nano-silica.

[0016] This invention also provides a method for preparing the highly compatible starch-based biodegradable plastic, comprising the following steps:

[0017] Step 1: Preparation of thermoplastic starch: Mix starch and glycerol at a mass ratio of 8:2-9:1, add to a high-speed mixer, mix at 80-100℃ for 10-20 minutes, and then feed into a twin-screw extruder for plasticizing and granulation to obtain thermoplastic starch granules;

[0018] Step 2: Premixing: Add polylactic acid, PBAT and / or PBS, tributyl acetylacetate, plasticizer, toughening agent, polyethylene glycol, compatibilizer, degradation accelerator, lubricant, hydrolysis aid, grafting agent, inorganic filler, compatibilizer, antioxidant and nanofiller into a high-speed mixer according to the formula ratio, and mix at 60-80℃ for 5-10 min to obtain the premix;

[0019] Step 3: Co-extrusion: Add the thermoplastic starch granules prepared in Step 1 and the premix obtained in Step 2 into a twin-screw extruder, control the extrusion temperature at 160-190℃ and the screw speed at 180-220r / min, and extrude and granulate to obtain highly compatible starch-based biodegradable plastic granules.

[0020] Furthermore, the temperature distribution of the twin-screw extruder in step 3 is as follows: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 180-190℃, and the die head 170-180℃.

[0021] The advantages of this invention are:

[0022] This invention improves the compatibility between TPS, PLA and PBAT / PBS by combining compatibilizers, additives and compatibilizers, effectively suppresses phase separation and improves the overall mechanical properties of the materials;

[0023] Adding degradation promoters and hydrolysis aids allows for the control of the material's degradation rate according to actual needs, thus broadening the material's application range.

[0024] Introducing grafting agents can form chemical cross-linking points between components, further enhancing interfacial bonding and improving the mechanical properties and thermal stability of the material;

[0025] The addition of inorganic and nano fillers not only reduces material costs but also provides reinforcement, improving the rigidity and dimensional stability of the material.

[0026] The preparation method of the present invention is simple and easy to implement, has stable processing performance, and is suitable for large-scale industrial production. Detailed Implementation

[0027] The present invention will be described in detail below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0028] Example 1

[0029] This embodiment provides a highly compatible starch-based biodegradable plastic, which, by weight, comprises the following raw materials: 50 parts thermoplastic starch, 30 parts polylactic acid (weight average molecular weight 80,000), 10 parts PBAT (weight average molecular weight 50,000), 0.5 parts tributyl acetylacetic acid, 5 parts plasticizer, 3 parts ethylene-vinyl acetate copolymer, 0.5 parts polyethylene glycol, 2 parts maleic anhydride-grafted polyethylene, 1 part oxalic acid, 0.3 parts zinc stearate, 0.5 parts adipic acid, 0.5 parts diphenylmethane diisocyanate, 2 parts calcium carbonate-talc (1:1), 3 parts propylene oxide-ethylene oxide copolymer, 0.05 parts antioxidant, and 0.5 parts nano-montmorillonite.

[0030] Plasticizers refer to plasticizer products manufactured by BASF in Germany.

[0031] Preparation method:

[0032] Step 1: Mix starch and glycerin at a mass ratio of 8:2, add to a high-speed mixer, mix at 80°C for 10 minutes, and then feed into a twin-screw extruder for plasticizing and granulation to obtain thermoplastic starch granules;

[0033] Step 2: Add the other ingredients in the above formula to a high-speed mixer and mix at 60°C for 5 minutes to obtain a premix;

[0034] Step 3: Add thermoplastic starch granules and premix to a twin-screw extruder, control the extrusion temperature at 160℃ in zone 1, 170℃ in zone 2, 180℃ in zone 3, 180℃ in zone 4, 170℃ at the die head, and 180 r / min at the screw speed, and extrude and granulate to obtain highly compatible starch-based biodegradable plastic granules.

[0035] Example 2

[0036] A highly compatible starch-based biodegradable plastic, by weight, comprises the following raw materials: 60 parts thermoplastic starch, 45 parts polylactic acid (weight average molecular weight 120,000), 25 parts PBS (weight average molecular weight 90,000), 5 parts tributyl acetylacetic acid, 10 parts plasticizer, 6 parts acrylonitrile-butadiene-styrene copolymer, 5 parts polyethylene glycol, 6 parts maleic anhydride-grafted polyethylene, 2 parts citric acid, 1 part zinc stearate, 1.5 parts adipic acid, 1 part diphenylmethane diisocyanate, 8 parts calcium carbonate-talc (1:1), 5 parts propylene oxide-ethylene oxide copolymer, 0.2 parts antioxidant, and 5 parts nano silica.

[0037] Preparation method:

[0038] Step 1: Mix starch and glycerin at a mass ratio of 8.5:1.5, add to a high-speed mixer, mix at 90°C for 15 minutes, and then feed into a twin-screw extruder for plasticizing and granulation to obtain thermoplastic starch granules;

[0039] Step 2: Add the other ingredients in the above formula to a high-speed mixer and mix at 70°C for 8 minutes to obtain a premix;

[0040] Step 3: Add thermoplastic starch granules and premix to a twin-screw extruder, control the extrusion temperature at 165℃ in zone 1, 175℃ in zone 2, 185℃ in zone 3, 185℃ in zone 4, 175℃ at the die head, and 200 r / min for extrusion granulation to obtain highly compatible starch-based biodegradable plastic granules.

[0041] Example 3

[0042] A highly compatible starch-based biodegradable plastic, by weight, comprises the following raw materials: 70 parts thermoplastic starch, 60 parts polylactic acid (weight average molecular weight 150,000), 40 parts PBAT (weight average molecular weight 100,000), 10 parts tributyl acetylacetic acid, 15 parts plasticizer, 10 parts ethylene-vinyl acetate copolymer, 10 parts polyethylene glycol, 10 parts maleic anhydride-grafted polyethylene, 3 parts oxalic acid, 2 parts zinc stearate, 3 parts adipic acid, 2 parts diphenylmethane diisocyanate, 15 parts calcium carbonate-talc (1:1), 8 parts propylene oxide-ethylene oxide copolymer, 0.5 parts antioxidant, and 10 parts nano-montmorillonite.

[0043] Preparation method:

[0044] Step 1: Mix starch and glycerin at a mass ratio of 9:1, add to a high-speed mixer, mix at 100°C for 20 minutes, and then feed into a twin-screw extruder for plasticizing and granulation to obtain thermoplastic starch granules;

[0045] Step 2: Add the other ingredients in the above formula to a high-speed mixer and mix at 80°C for 10 minutes to obtain a premix;

[0046] Step 3: Add thermoplastic starch granules and premix to a twin-screw extruder, control the extrusion temperature at 170℃ in zone 1, 180℃ in zone 2, 190℃ in zone 3, 190℃ in zone 4, 180℃ at the die head, and 220 r / min for screw speed, and extrude and granulate to obtain highly compatible starch-based biodegradable plastic granules.

[0047] Comparative Example 1

[0048] Compared with Example 2, no compatibilizer, maleic anhydride-grafted polyethylene, and compatibilizer, propylene oxide-ethylene oxide copolymer, were added; other raw materials and preparation methods were the same.

[0049] Comparative Example 2

[0050] Compared with Example 2, the degradation promoter citric acid and the hydrolysis aid adipic acid were not added, but the other raw materials and preparation methods were the same.

[0051] Comparative Example 3

[0052] Compared with Example 2, no grafting agent was added, but other raw materials and preparation methods were the same.

[0053] Experimental data and performance testing

[0054] The plastic granules prepared in Examples 1-3 and Comparative Examples 1-3 were injection molded into standard samples, and their performance was tested according to the following standards:

[0055] - Tensile strength: Tested according to GB / T 1040.3-2006, with a tensile rate of 50 mm / min;

[0056] - Impact strength: Tested according to GB / T 1843-2008, unnotched impact test on simply supported beam;

[0057] - Elongation at break: Tested according to GB / T 1040.3-2006;

[0058] - Degradation performance: The biodegradation rate was tested for 60 days under composting conditions (temperature 58±2℃, humidity 55±5%) according to GB / T 19277.1-2011.

[0059] The test results are shown in the table below:

[0060]

[0061] The test results above show that the highly compatible starch-based biodegradable plastics prepared in Examples 1-3 of this invention possess excellent tensile strength, impact strength, and elongation at break, while also exhibiting a high biodegradability rate. Compared to Comparative Example 1, the mechanical properties and degradation performance of the material were significantly improved after adding compatibilizers and additives, indicating that the compound compatibilizer system can effectively improve the compatibility between the components. Compared to Comparative Example 2, the biodegradability rate of the plastic was significantly increased after adding degradation promoters and hydrolysants, indicating that they can effectively regulate the degradation rate. Compared to Comparative Example 3, the mechanical properties of the material were significantly enhanced after adding grafting agents, indicating that grafting agents can enhance interfacial bonding and improve the mechanical properties of the plastic.

[0062] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A highly compatible starch-based biodegradable plastic, characterized in that, By weight, the raw materials include: 50-70 parts thermoplastic starch, 30-60 parts polylactic acid, 10-40 parts PBAT and / or PBS, 0.5-10 parts tributyl acetylacetate, 5-15 parts plasticizer, 3-10 parts toughening agent, 0.5-10 parts polyethylene glycol, 2-10 parts compatibilizer, 1-3 parts degradation accelerator, 0.3-2 parts lubricant, 0.5-3 parts hydrolysis aid, 0.5-2 parts grafting agent, 2-15 parts inorganic filler, 3-8 parts compatibilizer, 0.05-0.5 parts antioxidant, and 0.5-10 parts nanofiller.

2. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The thermoplastic starch is obtained by plasticizing starch with glycerol, and the mass ratio of starch to glycerol is 8:2-9:1; the inorganic filler is calcium carbonate and talc, and the mass ratio of calcium carbonate to talc is 1:

1.

3. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The polylactic acid has a weight-average molecular weight of 80,000-150,000; the PBAT has a weight-average molecular weight of 50,000-100,000; and the PBS has a weight-average molecular weight of 60,000-120,000.

4. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, Plasticizers refer to plasticizer products manufactured by BASF AG, Germany, and the toughening agents are ethylene-vinyl acetate copolymers or acrylonitrile-butadiene-styrene copolymers.

5. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polyethylene; the compatibilizer is propylene oxide-ethylene oxide copolymer.

6. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The degradation promoter is oxalic acid or citric acid; the hydrolysis aid is adipic acid.

7. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The grafting agent is diphenylmethane diisocyanate; the lubricant / processing aid is zinc stearate.

8. The highly compatible starch-based biodegradable plastic according to claim 1, characterized in that, The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the nanofiller is nano-montmorillonite or nano-silica.

9. A method for preparing a highly compatible starch-based biodegradable plastic as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Preparation of thermoplastic starch: Mix starch and glycerol at a mass ratio of 8:2-9:1, add to a high-speed mixer, mix at 80-100℃ for 10-20 minutes, and then feed into a twin-screw extruder for plasticizing and granulation to obtain thermoplastic starch granules; Step 2: Premixing: Add polylactic acid, PBAT and / or PBS, tributyl acetylacetate, plasticizer, toughening agent, polyethylene glycol, compatibilizer, degradation accelerator, lubricant, hydrolysis aid, grafting agent, inorganic filler, compatibilizer, antioxidant and nanofiller into a high-speed mixer according to the formula ratio, and mix at 60-80℃ for 5-10 min to obtain the premix; Step 3: Co-extrusion: Add the thermoplastic starch granules prepared in Step 1 and the premix obtained in Step 2 into a twin-screw extruder, control the extrusion temperature at 160-190℃ and the screw speed at 180-220r / min, and extrude and granulate to obtain fully degradable granules.

10. The method for preparing a highly compatible starch-based biodegradable plastic according to claim 9, characterized in that, In step 3, the temperature distribution of the twin-screw extruder is as follows: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 180-190℃, and the die head 170-180℃.

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