Preparation process of degradable plastic particles

Abstract

The invention discloses a preparation process of degradable plastic particles. The preparation process comprises the following steps: S1, weighing the following raw materials in parts by weight: 100-120 parts of polystyrene, 15-25 parts of modified starch, 30-50 parts of nanocellulose, 5-11 parts of a flame retardant, 3-6 parts of a degradation agent and 4-7 parts of a plasticizer; S2, adding the polystyrene, the modified starch and the nanocellulose into a high-speed mixer, and carrying out primary mixing to obtain a premix; s3, adding a flame retardant, a degradation agent and a plasticizer into the premix, and performing secondary mixing to obtain a mixture; and S4, adding the mixture into a double-screw extruder, and then performing extrusion, cooling and granulation to obtain the degradable plastic particles. According to the scheme, the modified starch is added into the ingredients, so that the environmental protection performance of the plastic particles can be remarkably improved. According to the scheme, the 90-day degradation rate reaches 80% or above, by adding the modified starch, the degradation degree of the plastic particles can be improved, and compared with a contrast, the plastic particles have the excellent degradation rate, elongation at break and tensile strength.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic particle preparation, and more specifically, to a preparation process for degradable plastic particles. Background Art

[0002] Degradable plastics are a type of plastic material with the ability to decompose relatively quickly in the natural environment. They are usually designed to be able to decompose into smaller compounds under appropriate conditions (such as specific temperature, humidity, microbial action, etc.) and ultimately completely degrade into acceptable residues such as water, carbon dioxide, and biomass. The following are several common types of degradable plastics and their characteristics:

[0003] 1. Bio-based degradable plastics: (1) Starch-based plastics: Plastics mainly made of starch, usually combined with other polymers (such as polylactic acid). They can be degraded by microorganisms under moist and appropriate temperature conditions. (2) Polylactic acid (PLA): Polylactic acid plastics obtained from plant sources such as corn can be degraded by microorganisms into carbon dioxide and water.

[0004] 2. Synthetic degradable plastics: (1) Polyacrylate (PPA): This type of plastic can be decomposed into non-toxic products through hydrolysis and will not cause persistent pollution to the environment. (2) Polycaprolactone (PCL): A synthetic plastic with good degradability, which can be degraded by microorganisms into carbon dioxide and water under appropriate conditions.

[0005] 3. Photo-biodegradable plastics: (3) Photo-biodegradable polymers: This type of plastic usually combines photosensitizers and biodegradability, enabling it to decompose rapidly under light and appropriate environmental conditions.

[0006] However, degradable plastics have strict environmental requirements and usually require specific environmental conditions (such as appropriate temperature, humidity, and microbial activity). They may not be easily degraded or the degradation rate may be slow in inappropriate environments. At the same time, existing degradable plastics often contain excessive additives such as plasticizers, colorants, fillers, etc., resulting in the plastics not meeting the degradation requirements and polluting the environment. Summary of the Invention

[0007] The purpose of the present invention is to provide a preparation process for degradable plastic particles to solve the technical problems existing in the above background art.

[0008] The technical solution of the present invention provides a preparation process for degradable plastic particles, including the following steps:

[0009] S1: Weigh the following raw materials in parts by weight: 100 - 120 parts of polystyrene, 15 - 25 parts of modified starch, 30 - 50 parts of nanocellulose, 5 - 11 parts of flame retardant, 3 - 6 parts of degradation agent, and 4 - 7 parts of plasticizer.

[0010] S2: Add polystyrene, modified starch, and nanocellulose into a high-speed mixer for primary mixing to obtain a premix.

[0011] S3: Then add a flame retardant, a degrading agent, and a plasticizer into the premix for secondary mixing to obtain a mixture.

[0012] S4: Add the mixture into a twin-screw extruder, and set the parameters of the twin-screw extruder as follows: the temperature is 220 - 250 °C, the screw speed is 180 - 225 r / min, and then carry out extrusion, cooling, and pelletizing to obtain degradable plastic pellets.

[0013] In a preferred embodiment, the flame retardant is one or more of magnesium hydroxide, aluminum hydroxide, and ammonium polyphosphate.

[0014] In a preferred embodiment, the degrading agent is one or more of carbon monoxide copolymer, ketene copolymer, poly(lactic acid), and poly-β-hydroxybutyric acid.

[0015] In a preferred embodiment, the plasticizer is one or more of citrate ester, phthalate ester, and polyethylene glycol.

[0016] In a preferred embodiment, the mixing speed of the primary mixing process is 200 - 300 r / min, the mixing time is 20 - 35 min, and the mixing temperature is 30 - 50 °C.

[0017] In a preferred embodiment, the mixing speed of the secondary mixing process is 320 - 500 r / min, the mixing time is 20 - 35 min, and the mixing temperature is 55 - 65 °C.

[0018] In a preferred embodiment, the preparation method of the modified starch is as follows: add starch into an ethanol solution with a concentration of 70% to obtain a mixed solution; then add an esterifying agent into the mixed solution, and the parameters are: temperature 50 - 70 °C, rotation speed 200 - 300 r / min, stirring time 30 - 70 min, and then keep the temperature and let it stand for reaction for 8 - 12 h to obtain the modified starch.

[0019] In a preferred embodiment, the esterifying agent is acetic anhydride.

[0020] In a preferred embodiment, the mass ratio of the starch, the ethanol solution, and the esterifying agent is (8 - 11):(23 - 31):(3 - 7).

[0021] The beneficial effects of the technical solution of the present invention are:

[0022] This solution can significantly improve the environmental performance of plastic particles by adding modified starch to the formulation. The degradation rate of this solution reaches over 80% in 90 days. By adding modified starch in this solution, the degradation degree of plastic particles can be increased. Compared with the comparative example, it has relatively excellent degradation rate, elongation at break, and tensile strength. Detailed implementation mode

[0023] The present invention will be further described in detail below. The embodiments of the present invention are given for the convenience of illustration and description, and are not exhaustive or limited to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

[0024] Example 1

[0025] The technical solution of the present invention provides a preparation process for degradable plastic particles, including the following steps:

[0026] S1: Weigh the following raw materials in parts by weight: 100 parts of polystyrene, 15 parts of modified starch, 30 parts of nanocellulose, 51 parts of flame retardant, 3 parts of degradation agent, and 4 parts of plasticizer.

[0027] S2: Add polystyrene, modified starch, and nanocellulose to a high-speed mixer for primary mixing to obtain a premix; the mixing speed is 200 r / min, the mixing time is 20 min, and the mixing temperature is 30 °C.

[0028] S3: Then add the flame retardant, degradation agent, and plasticizer to the premix for secondary mixing to obtain a mixture; the mixing speed for the secondary mixing process is 320 r / min, the mixing time is 20 min, and the mixing temperature is 55 °C.

[0029] S4: Add the mixture to a twin-screw extruder, set the parameters of the twin-screw extruder as follows: the temperature is 220 °C, the screw speed is 180 r / min, and then perform extrusion, cooling, and pelletizing to obtain degradable plastic particles.

[0030] The flame retardant is magnesium hydroxide. The degradation agent is a carbon monoxide copolymer. The plasticizer is a citrate ester.

[0031] The preparation method of the modified starch is as follows: Add starch into an ethanol solution with a concentration of 70% to obtain a mixture; then add an esterifying agent into the mixture, with the parameters: temperature 50°C, rotation speed 200 r / min, stirring time 300 min, and then keep the temperature and let it stand for reaction for 8 h to obtain the modified starch. The esterifying agent is acetic anhydride. The mass ratio of the starch, ethanol solution and esterifying agent is 8:23:3.

[0032] Example 2

[0033] The technical solution of the present invention provides a preparation process of degradable plastic particles, including the following steps:

[0034] S1: Weigh the following raw materials by weight: 120 parts of polystyrene, 25 parts of modified starch, 50 parts of nanocellulose, 11 parts of flame retardant, 6 parts of degradation agent, 7 parts of plasticizer.

[0035] S2: Add polystyrene, modified starch, and nanocellulose into a high-speed mixer for primary mixing to obtain a premix; the mixing speed of the primary mixing process is 300 r / min, the mixing time is 35 min, and the mixing temperature is 30 - 50°C.

[0036] S3: Then add the flame retardant, degradation agent, and plasticizer into the premix for secondary mixing to obtain a mixture; the mixing speed of the secondary mixing process is 500 r / min, the mixing time is 35 min, and the mixing temperature is 65°C.

[0037] S4: Add the mixture into a twin-screw extruder, and set the parameters of the twin-screw extruder as: temperature 250°C, screw rotation speed 225 r / min, and then carry out extrusion, cooling, and granulation to obtain degradable plastic particles.

[0038] The flame retardant is aluminum hydroxide. The degradation agent is ethylene ketone copolymer. The plasticizer is phthalate.

[0039] The preparation method of the modified starch is as follows: Add starch into an ethanol solution with a concentration of 70% to obtain a mixture; then add an esterifying agent into the mixture, with the parameters: temperature 70°C, rotation speed 300 r / min, stirring time 70 min, and then keep the temperature and let it stand for reaction for 12 h to obtain the modified starch. The esterifying agent is acetic anhydride. The mass ratio of the starch, ethanol solution and esterifying agent is 11:31:7.

[0040] Example 3

[0041] The technical solution of the present invention provides a preparation process of degradable plastic particles, including the following steps:

[0042] S1: Weigh the following raw materials by weight: 110 parts of polystyrene, 20 parts of modified starch, 40 parts of nanocellulose, 8 parts of flame retardant, 5 parts of degradation agent, and 6 parts of plasticizer.

[0043] S2: Add polystyrene, modified starch, and nanocellulose to a high-speed mixer for primary mixing to obtain a premix; the mixing speed of the primary mixing process is 240 r / min, the mixing time is 25 min, and the mixing temperature is 40 °C.

[0044] S3: Then add the flame retardant, degradation agent, and plasticizer to the premix for secondary mixing to obtain a mixture; the mixing speed of the secondary mixing process is 320 - 500 r / min, the mixing time is 28 min, and the mixing temperature is 60 °C.

[0045] S4: Add the mixture to a twin-screw extruder, set the parameters of the twin-screw extruder as: temperature 220 - 250 °C, screw speed 180 - 225 r / min, and then perform extrusion, cooling, and pelletizing to obtain degradable plastic pellets.

[0046] The flame retardant is ammonium polyphosphate. The degradation agent is poly(lactic acid). The plasticizer is polyethylene glycol.

[0047] The preparation method of the modified starch is as follows: Add starch to an ethanol solution with a concentration of 70% to obtain a mixed solution; then add an esterifying agent to the mixed solution, with parameters: temperature 60 °C, rotation speed 230 r / min, stirring time 30 - 70 min, and then keep the temperature and let it stand for reaction for 8 - 12 h to obtain modified starch. The esterifying agent is acetic anhydride. The mass ratio of the starch, ethanol solution, and esterifying agent is (9:(25):4.

[0048] Example 4

[0049] The technical solution of the present invention provides a preparation process for degradable plastic pellets, including the following steps:

[0050] S1: Weigh the following raw materials by weight: 105 parts of polystyrene, 22 parts of modified starch, 45 parts of nanocellulose, 7 parts of flame retardant, 5 parts of degradation agent, and 5 parts of plasticizer.

[0051] S2: Add polystyrene, modified starch, and nanocellulose to a high-speed mixer for primary mixing to obtain a premix; the mixing speed of the primary mixing process is 220 r / min, the mixing time is 26 min, and the mixing temperature is 45 °C.

[0052] S3: Then add the flame retardant, degradation agent, and plasticizer to the premix for secondary mixing to obtain a mixture; the mixing speed of the secondary mixing process is 340 r / min, the mixing time is 27 min, and the mixing temperature is 58 °C.

[0053] S4: Add the mixture into a twin-screw extruder, and set the parameters of the twin-screw extruder as follows: the temperature is 230 °C, the screw rotation speed is 190 r / min, and then carry out extrusion, cooling, and pelletizing to obtain degradable plastic pellets.

[0054] The flame retardant is a mixture of magnesium hydroxide and aluminum hydroxide. The degradation agent is a mixture of poly(lactic acid) and poly(β-hydroxybutyric acid). The plasticizer is polyethylene glycol.

[0055] The preparation method of the modified starch is as follows: Add starch into an ethanol solution with a concentration of 70%, and obtain a mixed solution; then add an esterifying agent into the mixed solution, with the parameters: temperature 62 °C, rotation speed 260 r / min, stirring time 50 min, and then keep the temperature and let it stand for reaction for 10 h to obtain modified starch. The esterifying agent is acetic anhydride. The mass ratio of starch, ethanol solution, and esterifying agent is 11:26:5.

[0056] Comparative Example 1

[0057] Compared with Example 1, the difference is that the modified starch is replaced with ordinary starch.

[0058] Comparative Example 2

[0059] This comparative example is the degradable plastic disclosed in Chinese Patent CN118307885A.

[0060] Comparative Example 3

[0061] This comparative example is the degradable plastic disclosed in Chinese Patent CN102453285A.

[0062] Perform performance tests on the plastic pellets prepared in Examples 1-4 and Comparative Examples 1-3. Prepare the above-mentioned examples into plastic products, and test the examples and comparative examples under the same conditions. The test results are shown in Table 1 below:

[0063] Table 1

[0064]

[0065]

[0066] As can be seen from the data in Table 1, the degradation rate in this solution reaches more than 80% in 90 days. In this solution, by adding modified starch, the degradation degree of plastic pellets can be improved. Compared with the comparative examples, it has relatively excellent degradation rate, elongation at break, and tensile strength.

[0067] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art and related fields based on the embodiments in the present invention without creative efforts shall fall within the scope of protection of the present invention. Structures, devices, and operation methods not specifically described and explained in the present invention shall be implemented by conventional means in the art unless otherwise specified and limited.

Claims

1. A preparation process for degradable plastic particles, characterized in that, It includes the following steps: S1: Weigh the following raw materials in parts by weight: 100 - 120 parts of polystyrene, 15 - 25 parts of modified starch, 30 - 50 parts of nanocellulose, 5 - 11 parts of flame retardant, 3 - 6 parts of degradation agent, and 4 - 7 parts of plasticizer. S2: Add polystyrene, modified starch, and nanocellulose into a high - speed mixer for primary mixing to obtain a premix. S3: Then add the flame retardant, degradation agent, and plasticizer into the premix for secondary mixing to obtain a mixture. S4: Add the mixture into a twin - screw extruder, and set the parameters of the twin - screw extruder as follows: the temperature is 220 - 250 °C, the screw speed is 180 - 225 r / min, and then carry out extrusion, cooling, and pelletizing to obtain degradable plastic pellets.

2. The preparation process of a degradable plastic particle according to claim 1, wherein The flame retardant is one or more of magnesium hydroxide, aluminum hydroxide, and ammonium polyphosphate.

3. The preparation process of the degradable plastic particles according to claim 1, characterized in that, The degradation agent is one or more of carbon monoxide copolymer, ketene copolymer, polylactide, and poly - β - hydroxybutyric acid.

4. The preparation process of a degradable plastic particle according to claim 1, wherein, The plasticizer is one or more of citrate ester, phthalate ester, and polyethylene glycol.

5. A preparation process of degradable plastic particles according to claim 1, characterized in that, The mixing speed of the primary mixing process is 200 - 300 r / min, the mixing time is 20 - 35 min, and the mixing temperature is 30 - 50 °C.

6. The preparation process of a degradable plastic particle according to claim 1, characterized in that, The mixing speed of the secondary mixing process is 320 - 500 r / min, the mixing time is 20 - 35 min, and the mixing temperature is 55 - 65 °C.

7. A preparation process for degradable plastic particles according to claim 1, characterized in that, The preparation method of the modified starch is as follows: Add starch into an ethanol solution with a concentration of 70%, to obtain a mixed solution; then add an esterifying agent into the mixed solution, with the parameters: temperature 50 - 70 °C, rotation speed 200 - 300 r / min, stirring time 30 - 70 min, and then keep the temperature and let it stand for reaction for 8 - 12 h to obtain modified starch.

8. A preparation process for degradable plastic particles according to claim 7, characterized in that, The esterifying agent is acetic anhydride.

9. A preparation process of degradable plastic particles according to claim 7, characterized in that, The mass ratio of the starch, ethanol solution, and esterifying agent is (8 - 11):(23 - 31):(3 - 7).

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