Metal salt modified thermoplastic starch filled PBAT-based composite material, preparation method and application

Abstract

The invention provides a metal salt modified thermoplastic starch filled PBAT-based composite material as well as a preparation method and application thereof. The plastic film is prepared from the following components in parts by weight: 25-35 parts of thermoplastic starch, 60-70 parts of poly (butylene terephthalate)-adipate, 1-10 parts of polylactic acid, 0.1-1 part of an antioxidant, 0.1-1 part of an anti-hydrolysis agent and 0.1-1 part of a dispersing agent. 0.1-1 part by weight of an anti-blocking agent and the like are added into a high-speed mixer step by step according to a particle-liquid-powder sequence to be mixed; and extruding through a double-screw extruder, air-cooling and pelletizing to obtain the PBAT-based composite material. The metal ions and the starch hydroxyl form a coordination effect, so that the mechanical property of the PBAT-based composite material is remarkably improved, and the cost is reduced while the mechanical property of a pure PBAT material is reserved. In addition, the waistcoat type non-food contact biodegradable shopping bag made of the PBAT-based composite material can bear the weight of 5 kg, and the degradation performance meets the requirements of GB / T 38082-2019.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biodegradable plastics, and particularly relates to a metal salt modified thermoplastic starch filled PBAT-based composite material, a preparation method and application. BACKGROUND

[0002] In recent years, plastics using petroleum as raw materials are used in large quantities, which are difficult to degrade and accumulate, and gradually expose the impact on the environment. With the gradual improvement of people's environmental protection consciousness and the shortage of petrochemical resources, developing biodegradable materials is a feasible method to replace traditional materials. Biodegradable material polybutylene adipate terephthalate (PBAT) has the properties of softness and toughness, and its processing performance is equivalent to that of low-density polyethylene (LDPE). It is widely used to alleviate the environmental pollution problem caused by traditional materials. However, PBAT has a slow melt cooling rate and high viscosity, and the opening property of the film directly blown from PBAT is very poor. In addition, the price of PBAT is higher than that of traditional materials, which increases the cost of products.

[0003] Starch is a natural polymer material, which has the advantages of wide source, low price, complete biodegradability and easy processing. The PBAT material is blended with the thermoplastic starch (TPS) processed from starch and plasticizer glycerol, which not only reduces the cost, but also improves the poor opening property of the film. Chinese patent CN116656011A dissolves soluble salt in water, mixes with plasticizer, and then mixes with starch to obtain modified TPS by extrusion. Then, PBAT and the like are mixed and extruded to prepare PBAT / TPS composite material with high temperature and humidity resistance, low migration and low mechanical properties of about 11 MPa. Chinese patent CN120464148A mixes positively charged aluminum ions with negatively charged lignin by ball milling in advance. Due to the strong electrostatic interaction between aluminum ions and lignin, the two are aggregated to form aluminum ion clusters. The aluminum ion clusters are introduced in the starch plasticization process, and then are melt blended with PBAT. The introduced aluminum ion clusters can effectively complex with thermoplastic starch and lignin to form a metal ion dynamic crosslinking structure, which effectively improves the dispersion of thermoplastic starch in the PBAT matrix. However, the mechanical properties of the obtained composite material are only 11.34 MPa at most.

[0004] Based on the above, the use of metal salt modified thermoplastic starch to replace part of the PBAT material reduces the cost, but the mechanical properties of the composite material are only half of those of pure PBAT material. Therefore, it is very important to develop a metal salt modified thermoplastic starch filled PBAT-based composite material which not only reduces the cost, but also retains the mechanical properties of pure PBAT material. SUMMARY

[0005] To solve the above problems, the application discloses a kind of metal salt modified thermoplastic starch filled PBAT base composite material, preparation method and application.

[0006] In one aspect, the application provides a kind of metal salt modified thermoplastic starch filled PBAT base composite material, it is made of the following weight parts of components: Thermoplastic starch 25-35 parts by weight; Polybutylene adipate terephthalate 60-70 parts by weight; Polylactic acid 1-10 parts by weight; Antioxidant 0.1-1 parts by weight; Anti-hydrolysis agent 0.1-1 parts by weight; Dispersant 0.1-1 parts by weight; Opening agent 0.1-1 parts by weight.

[0007] Further, the antioxidant is one or a combination of antioxidant 168, antioxidant 1010 and antioxidant 1076.

[0008] Further, the anti-hydrolysis agent is one or a combination of monomeric carbodiimide and polymeric carbodiimide.

[0009] Further, the dispersant is white oil commonly used.

[0010] Further, the opening agent can include at least one of nano-Si , erucic acid amide, oleic acid amide, etc.

[0011] In another aspect, the application also provides a preparation method of the metal salt modified thermoplastic starch filled PBAT base composite material, which comprises the following steps: Step S1: 25-35 parts by weight of thermoplastic starch, 60-70 parts by weight of polybutylene adipate terephthalate, 1-10 parts by weight of polylactic acid, 0.1-1 parts by weight of antioxidant, 0.1-1 parts by weight of anti-hydrolysis agent, 0.1-1 parts by weight of dispersant, 0.1-1 parts by weight of opening agent, etc. are added to a high-speed mixer in the order of granules-liquids-powders for mixing; Step S2: extruded by a double-screw extruder, air-cooled, and pelletized to obtain the PBAT base composite material.

[0012] Further, in step S2, the temperature from the feeding port to the die head of the double-screw extruder is 90-165℃, and the screw rotation speed is 90-120r / min.

[0013] In another aspect, the application also provides a preparation method of thermoplastic starch, which comprises the following steps: Step S11, the starch is mixed with the metal salt, wherein the metal salt is 0.5-5% of the starch; Step S12, the plasticizer is sprayed into the mixture of the starch and the metal salt by atomization, and the mixture is continuously mixed uniformly, wherein the mass ratio of the starch to the plasticizer is 65:35-75:25. Step S13, the mixture is extruded and granulated by a double screw extruder to obtain the thermoplastic starch.

[0014] Further, in step S11, the starch is dried at 70-90℃ for more than 10h before use.

[0015] Further, in step S11, the starch includes at least one of corn starch, wheat starch, potato starch, etc.

[0016] Further, in step S12, the plasticizer is glycerol commonly used.

[0017] Further, in step S12, the metal salt includes at least one of magnesium sulfate, calcium chloride, zinc sulfate, magnesium citrate, zinc citrate, sodium lignosulfonate, etc.

[0018] Further, in step S13, the temperature of the feeding port to the die head of the double screw extruder is 90-135℃, and the screw rotation speed is 90-120r / min.

[0019] In other aspects, the application also provides an application of the metal salt modified thermoplastic starch filled PBAT based composite material in non-food contact biodegradable shopping bags and biodegradable garbage bags, including the following steps: the PBAT based composite material is blown into a film by a single screw extrusion film blowing machine, and then a bag making machine is used to make bags.

[0020] Further, the temperature of the single screw extrusion film blowing machine is 120-160℃, the blow ratio is 2-5, and the stretch ratio is 1-5.

[0021] Further, the temperature of the hot knife of the bag making machine can be 180-210℃.

[0022] The application has the following advantages and positive effects: (1) In the process of processing the thermoplastic starch, the amount of the metal salt used is small, and the metal ions form coordination with the hydroxyl groups of the starch.

[0023] (2) The tensile strength of the PBAT based composite material is up to 18.9MPa, and the elongation at break is up to 895.4%, the cost is not only lower than that of pure PBAT material, but also the mechanical properties are similar to those of pure PBAT material.

[0024] (3) The vest type non-food contact biodegradable shopping bag made of the PBAT-based composite material has excellent performance and can bear 5kg. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0026] Figure 1 is a macroscopic photo of thermoplastic starch particles prepared according to the embodiments of the present application; Figure 2 is a simple process flow diagram of the vest type non-food contact biodegradable shopping bag according to the embodiments of the present application; Figure 3 is a macroscopic photo of the vest type non-food contact biodegradable shopping bag produced according to the embodiment 7 of the present application; Figure 4 is the degradation performance of the vest type non-food contact biodegradable shopping bag produced according to the embodiment 7 of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] The technical solutions provided by the present application will be described in detail below in combination with specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0029] The present application provides a metal salt modified thermoplastic starch filled PBAT-based composite material, which is composed of the following components by weight: thermoplastic starch 25-35 parts by weight, polybutylene adipate terephthalate 60-70 parts by weight, polylactic acid 1-10 parts by weight, antioxidant 0.1-1 parts by weight, anti-hydrolysis agent 0.1-1 parts by weight, dispersing agent 0.1-1 parts by weight, opening agent 0.1-1 parts by weight.

[0030] In some specific embodiments, the antioxidant is one or a combination of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0031] In some specific embodiments, the anti-hydrolysis agent is one or a combination of monomeric carbodiimide, polymeric carbodiimide.

[0032] In some specific embodiments, the dispersing agent is a commonly used white oil.

[0033] In some specific embodiments, the opening agent can include at least one of nano-Si , erucic acid amide, oleic acid amide, etc.

[0034] The present application also provides a preparation method of a metal salt modified thermoplastic starch filled PBAT based composite material, which comprises the following steps: Step S1: 25-35 parts by weight of thermoplastic starch, 60-70 parts by weight of polybutylene adipate terephthalate, 1-10 parts by weight of polylactic acid, 0.1-1 parts by weight of antioxidant, 0.1-1 parts by weight of anti-hydrolysis agent, 0.1-1 parts by weight of dispersing agent, 0.1-1 parts by weight of opening agent, etc. are added to a high-speed mixer in the order of granules-liquids-powders for mixing; Step S2: extruded through a double screw extruder, air cooled, and granulated to obtain a PBAT based composite material.

[0035] In some specific embodiments, the temperature from the feeding port to the die head of the double screw extruder is 90-165℃, and the screw rotation speed is 90-120r / min.

[0036] The present application also provides a preparation method of thermoplastic starch, which comprises the following steps: S11, the starch is mixed with the metal salt uniformly, wherein the amount of metal salt is 0.5-5% of the starch; S12, the plasticizer is sprayed into the mixture of starch and metal salt by atomization, and continues to be mixed uniformly, wherein the mass ratio of starch to plasticizer is 65:35-75:25; S13, extruded through a double screw extruder and granulated to obtain thermoplastic starch.

[0037] In some specific embodiments, the starch is dried at 70-90℃ for more than 10h before use.

[0038] In some specific embodiments, the starch includes at least one of corn starch, wheat starch, potato starch, etc.

[0039] In some specific embodiments, the plasticizer is a commonly used glycerol.

[0040] In some specific embodiments, the metal salt comprises at least one of magnesium sulfate, calcium chloride, zinc sulfate, magnesium citrate, zinc citrate, sodium lignosulfonate, etc.

[0041] In some specific embodiments, the temperature of the feeding port to the die head of the twin-screw extruder is 90-135 DEG C, and the screw rotation speed is 90-120 r / min.

[0042] The application also provides an application of the metal salt modified thermoplastic starch filled PBAT-based composite material in the field of non-food contact biodegradable shopping bags, biodegradable garbage bags, etc., comprising the following steps: blowing a film by using a single-screw extrusion film blowing machine, and then using a bag making machine to make the bag.

[0043] Further, the temperature of the single-screw extrusion film blowing machine is 120-160 DEG C, the blow-up ratio is 2-5, and the stretch ratio is 1-5.

[0044] Further, the temperature of the hot knife of the bag making machine can be 180-210 DEG C.

[0045] Example 1 The starch was dried at 80 DEG C for more than 10 h, mixed with 3% anhydrous magnesium sulfate based on the mass of the starch, and then 30% glycerol was sprayed by atomization according to the mass ratio of the starch to the glycerol of 70:30. After being mixed uniformly, the mixture was added into a twin-screw extruder for extrusion. The temperature of the feeding port to the die head was 90-135 DEG C, and the screw rotation speed was 90 r / min. After being cooled and granulated, magnesium sulfate modified TPS particles were obtained. 30 parts by weight of the magnesium sulfate modified TPS, 63 parts by weight of PBAT, 5 parts by weight of PLA, 0.2 parts by weight of antioxidant 1010, 0.1 parts by weight of antioxidant 168, 0.2 parts by weight of hydrolysis-resistant agent monomeric carbodiimide, 0.5 parts by weight of nano-SiO2, and 1 part by weight of white oil were sequentially added into a high-speed mixer in the order of particles-liquid-powder for uniform mixing. The mixture was added into a twin-screw extruder for extrusion. The temperature of the feeding port to the die head was 90-165 DEG C, and the screw rotation speed was 100 r / min. After being air-cooled, granulated, and cooled, magnesium sulfate modified TPS filled PBAT-based composite material was obtained.

[0046] Example 2 The difference between this example and Example 1 is that 1% anhydrous calcium chloride based on the mass of the starch.

[0047] Example 3 The difference between this example and Example 1 is that 4% zinc sulfate monohydrate based on the mass of the starch.

[0048] Example 4 The difference between this example and Example 1 is that 3% anhydrous magnesium citrate based on the mass of the starch.

[0049] Example 5 The difference between this example and Example 1 is that 4% of the mass of the starch is zinc citrate dihydrate.

[0050] Example 6 The difference between this example and Example 1 is that 0.5% of the mass of the starch is sodium lignosulfonate.

[0051] Example 7 The magnesium sulfate modified TPS filled PBAT-based composite material obtained in Example 1 is blown into a film by a single-screw extrusion film blowing machine (temperature 120-160°C, blow-up ratio 2-5, stretch ratio 1-5), and then a vest-type non-food contact biodegradable shopping bag is made by a bag-making machine (hot knife temperature 180-210°C).

[0052] Comparative Example 1 The starch is dried at 80°C for more than 10 hours, and then glycerol is sprayed by atomization according to a mass ratio of 70:30 of starch to glycerol. After mixing uniformly, it is added to a twin-screw extruder for extrusion. The temperature from the feeding port to the die head of the twin-screw extruder is 90-135°C, and the screw speed is 90 r / min. After cooling and pelletizing, TPS particles are obtained. 30 parts by weight of TPS, 63 parts by weight of PBAT, 5 parts by weight of PLA, 0.2 parts by weight of antioxidant 1010, 0.1 parts by weight of antioxidant 168, 0.2 parts by weight of anti-hydrolysis agent monomeric carbodiimide, 0.5 parts by weight of nano-SiO2, and 1 part by weight of white oil are added to a high-speed mixer in the order of particles-liquid-powder for uniform mixing, and then added to a twin-screw extruder for extrusion. The temperature from the feeding port to the die head is 90-165°C, and the screw speed is 100 r / min. After air cooling, cutting, and pelletizing, a TPS filled PBAT-based composite material is obtained.

[0053] Comparative Example 2 Pure PBAT material.

[0054] The PBAT-based composite materials prepared in Examples 1-6 and Comparative Example 1, and the pure PBAT material of Comparative Example 2 are tested for mechanical properties by injection molding into dumbbell-shaped test pieces at 160-170°C (tested according to GB / T 1040.1-2006, tensile speed 100 mm / min). The test results are shown in Table 1. The costs of the PBAT-based composite materials prepared in Examples 1-6 and Comparative Example 1, and the pure PBAT material of Comparative Example 2 are calculated, and the results are shown in Table 2. The vest-type non-food contact shopping bag prepared in Example 7 is tested according to GB / T 38079-2019, and the test results are shown in Table 3 and Figure 4 Table 4.

[0055] Table 1 Mechanical property results of PBAT-based composite materials

[0056] Table 2 Cost of PBAT-based composite materials

[0057] Table 3 Performance results of vest-type non-food contact biodegradable shopping bags produced in Example 7

[0058] Table 1 is the mechanical property test results of PBAT-based composite materials prepared in the examples. As can be seen from Table 1, the mechanical properties of the PBAT-based composite materials prepared in Examples 1-6 are better than those of Comparative Example 1. This is because, after adding metal salts, the coordination effect of the hydroxyl groups on the starch and the metal ions, a crosslinked network structure based on coordination bonds is formed between the starch molecular chains. This structure is intertwined with PBAT and PLA, which significantly improves the mechanical properties of the PBAT-based composite materials. The introduction of TPS material in PBAT material makes the mechanical properties of the obtained PBAT-based composite material very close to those of pure PBAT material.

[0059] Table 2 is the cost of PBAT-based composite materials prepared in the examples. As can be seen from Table 2, after introducing TPS material in PBAT material, the cost of PBAT-based composite material is reduced by about 800-1000 yuan (cost only includes material cost) compared with pure PBAT material.

[0060] Table 3 is the performance test results of vest-type non-food contact biodegradable shopping bags prepared in Example 7. As can be seen from Table 3, after relevant tests, the vest-type non-food contact biodegradable shopping bags all show excellent performance, meeting the requirements of GB / T38079-2019, and can bear 5 kg.

[0061] Figure 1 is a macroscopic photo of thermoplastic starch prepared in the examples. The color of the thermoplastic starch prepared in Examples 1-5 is yellow, and the color of the thermoplastic starch prepared in Example 6 is coffee color.

[0062] Figure 2 is a schematic diagram of the processing flow of vest-type non-food contact biodegradable shopping bags.

[0063] Figure 3 is a macroscopic photo of vest-type non-food contact biodegradable shopping bags produced in Example 7 (length 500 mm, width 310 mm, folded edge 70 mm, thickness 45 µm), which is white and neatly placed.

[0064] Figure 4Degradation performance of the vest type non-food contact biodegradable shopping bag produced in Example 7: soil burial method (left figure) and industrial composting method (right figure). As can be seen from the left figure: after 180 days of soil burial, the vest type non-food contact biodegradable shopping bag has large holes. In addition, by comparing in different environments, appropriate temperature and humidity can help the degradation of the vest type non-food contact biodegradable shopping bag. As can be seen from the right figure: in the industrial composting environment, the biodegradation rate of the vest type non-food contact biodegradable shopping bag reaches 94%, and the relative biodegradation rate reaches 98%, meeting the requirements of GB / T 38082-2019.

[0065] The technical means disclosed in the present application scheme is not limited to the technical means disclosed in the above-mentioned embodiments, and also includes the technical solutions composed of any combination of the above technical features. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, which are considered to be within the scope of protection of the present application.

Claims

1. A metal salt modified thermoplastic starch filled PBAT based composite material, characterized in that, Composed of the following components by weight fraction: Thermoplastic starch 25-35 parts by weight; Polybutylene adipate terephthalate 60-70 parts by weight; Polylactic acid 1-10 parts by weight; Antioxidant 0.1-1 parts by weight; Anti-hydrolysis agent 0.1-1 parts by weight; Dispersing agent 0.1-1 parts by weight; Opening agent 0.1-1 parts by weight.

2. A metal salt modified thermoplastic starch filled PBAT based composite material according to claim 1, characterized in that, The antioxidant is one or more combinations of antioxidant 168, antioxidant 1010, antioxidant 1076; The anti-hydrolysis agent is one or more combinations of monomeric carbodiimide, polymeric carbodiimide; The dispersing agent is a commonly used white oil; The opening agent includes at least one of nano-Si , erucic acid amide, oleic acid amide.

3. A method of preparing a metal salt modified thermoplastic starch filled PBAT based composite material according to any one of claims 1-2, characterized in that, Comprising the following steps: Step S1: 25-35 parts by weight of thermoplastic starch, 60-70 parts by weight of polybutylene adipate terephthalate, 1-10 parts by weight of polylactic acid, 0.1-1 parts by weight of antioxidant, 0.1-1 parts by weight of anti-hydrolysis agent, 0.1-1 parts by weight of dispersing agent, 0.1-1 parts by weight of opening agent, etc. are added to the high-speed mixer in the order of granules-liquids-powders for mixing; Step S2: extruded by a double screw extruder, air-cooled, and granulated to obtain a PBAT-based composite material.

4. The method of preparing metal salt modified thermoplastic starch filled PBAT based composites as claimed in claim 3 wherein, In step S2, the temperature from the feeding port to the die head of the double screw extruder is 90-165℃, and the screw rotation speed is 90-120r / min.

5. The method of preparing metal salt modified thermoplastic starch filled PBAT based composites as claimed in claim 3 wherein, The preparation steps of the thermoplastic starch are as follows: Step S11, mix the starch and metal salt uniformly, wherein the amount of metal salt is 0.5-5% of the starch; Step S12, the plasticizer is sprayed into the mixture of starch and metal salt by atomization, and continues to mix uniformly, wherein the mass ratio of starch to plasticizer is 65:35-75:25; Step S13, extruded by a double screw extruder, and granulated to obtain thermoplastic starch.

6. The preparation method of the metal salt modified thermoplastic starch filled PBAT-based composite material according to claim 5, in step S11, the starch is dried at 70-90℃ for more than 10h before use.

7. The preparation method of the metal salt modified thermoplastic starch filled PBAT-based composite material according to claim 5, in step S11, the starch includes at least one of corn starch, wheat starch, and potato starch.

8. The preparation method of the metal salt modified thermoplastic starch filled PBAT-based composite material according to claim 5, in step S12, the plasticizer is a commonly used glycerol, and the metal salt includes at least one of magnesium sulfate, calcium chloride, zinc sulfate, magnesium citrate, zinc citrate, and sodium lignosulfonate.

9. The preparation method of the metal salt modified thermoplastic starch filled PBAT-based composite material according to claim 5, in step S13, the temperature from the feeding port to the die head of the double screw extruder is 90-135℃, and the screw rotation speed is 90-120r / min.

10. The application of a metal salt modified thermoplastic starch filled PBAT-based composite material in the field of non-food contact biodegradable shopping bags and biodegradable garbage bags according to any one of claims 1-2.

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