Degradable modified plastic particles and preparation method thereof

Abstract

The invention discloses degradable modified plastic particles and a preparation method thereof, and belongs to the technical field of preparation of modified plastic particles. The degradable modified plastic particles are prepared from the following components in parts by weight: 30 to 50 parts of polylactic acid, 2 to 6 parts of polyhydroxybutyrate, 20 to 40 parts of poly (butylene adipate / terephthalate), 5 to 10 parts of acetyl tributyl citrate, 2 to 4 parts of dodecyl trimethoxy silane, 2 to 8 parts of organic antibacterial agent and 10 to 20 parts of modified additive. The modified plastic particles prepared by the method have excellent antibacterial property, mechanical property and degradability.

Description

Technical Field

[0001] The present invention belongs to the technical field of plastic pellet preparation, and particularly relates to a degradable modified plastic pellet and a preparation method thereof. Background Art

[0002] Traditional plastics such as polyethylene and polypropylene take hundreds of years to degrade under natural conditions, and incineration treatment will produce toxic gases, exacerbating the greenhouse effect. Therefore, the development of degradable plastics with both practicality and environmental friendliness has become a research hotspot in the field of materials science.

[0003] Patent CN213832859U discloses a degradable plastic, including an inner-layer plastic. A surface-layer plastic is provided at the bottom of the inner-layer plastic. The surface-layer plastic includes bumps and grooves. The bumps are rectangular blocks, and the inside of the bumps is hollow. The bumps are fixedly installed on the bottom wall surface of the inner-layer plastic. The grooves are rectangular slot holes. In this degradable plastic of the invention, through the erosion grooves inside the grooves, oxygen and moisture in nature can more fully erode the plastic wall surface. At the same time, when eroding inside the erosion grooves, the plant sealant on the degradation infiltration grooves will be adaptively dissolved, so that the erosion penetrates into the inside of the bumps. Through the bumps and the inner through grooves, natural erosion degrades from the inside to the outside, and in cooperation with the grooves and the erosion grooves, the degradation erosion can be completed more comprehensively and quickly, so as to achieve the effect of rapid degradation. However, there is still room for improvement in the degradable performance, antibacterial performance, and mechanical properties of the plastic prepared by this method. Summary of the Invention

[0004] The purpose of the present invention is to provide a degradable modified plastic pellet and a preparation method thereof, which are used to solve the technical problems of poor degradation performance, antibacterial performance, and mechanical properties of plastic pellets in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a degradable modified plastic pellet, which is composed of the following components in parts by weight: 30-50 parts of polylactic acid, 2-6 parts of polyhydroxybutyrate, 20-40 parts of polybutylene adipate / terephthalate, 5-10 parts of tributyl acetylcitrate, 2-4 parts of dodecyltrimethoxysilane, 2-8 parts of an organic antibacterial agent, and 10-20 parts of a modified additive. Among them, the organic antibacterial agent is mainly prepared from p-methoxybenzaldehyde, hexahydropyridine, 2,3-butanedione, p-fluorobenzaldehyde, and boron tribromide as raw materials, and the modified additive is mainly prepared from cassava starch, 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, sodium chloroacetate, and sodium hydroxide as raw materials.

[0007] Preferably, the preparation method of the organic antibacterial agent includes the following steps:

[0008] Q1: Add p-methoxybenzaldehyde, hexahydropyridine, and methanol into a container, stir to dissolve, slowly heat up, and then use a constant pressure dropping funnel to dropwise add a mixed solution of 2,3-butanedione and methanol. Control the dropping time. After the dropping is completed, continue the reaction. After the reaction is completed, cool, perform suction filtration under reduced pressure, wash, dry, and recrystallize to obtain Product 1;

[0009] Q2: Add Product 1, p-fluorobenzaldehyde, ammonium acetate, and glacial acetic acid into a container, heat and react in an oil bath. After the reaction is completed, cool, perform rotary evaporation under reduced pressure, filter, add the filtrate into ice water, adjust the pH, stir at low temperature, continue suction filtration under reduced pressure, wash, dry, wash again, and recrystallize to obtain Product 2;

[0010] Q3: Under a low-temperature environment, add Product 2 into a container containing dichloromethane, and then slowly dropwise add boron tribromide. After the dropping is completed, heat up the reaction. After the reaction is completed, quench the reaction, concentrate under reduced pressure, wash, recrystallize, and dry to obtain the organic antibacterial agent.

[0011] In the above process, the synthesis reaction formula of the organic antibacterial agent is as follows:

[0012]

[0013] The results of mass spectrometry analysis of Product 1 are: m / z: 322.12 (100.0%), 323.12 (21.8%), 324.13 (2.3%); the results of mass spectrometry analysis of Product 2 are: m / z: 426.17 (100.0%), 427.18 (29.5%), 428.18 (4.6%); the results of mass spectrometry analysis of the organic antibacterial agent are: m / z: 398.14 (100.0%), 399.15 (27.3%), 400.15 (4.0%).

[0014] Preferably, in Q1, the dosage ratio of p-methoxybenzaldehyde, hexahydropyridine, and 2,3-butanedione is (10 - 16.27) g : (3.82 - 4.95) g : (4.11 - 4.63) g, heat up to 50 - 55 °C, the dropping time is 4 - 6 h, the continued reaction time is 3 - 5 h, wash with methanol, and recrystallize with absolute ethanol and N,N-dimethylformamide.

[0015] Preferably, in Q2, the dosage ratio of product 1, p-fluorobenzaldehyde, ammonium acetate and glacial acetic acid is (0.88 - 1.25) g : (0.55 - 0.79) g : (2.11 - 2.45) g : (25 - 38) mL. The heating reaction temperature is 115 - 120 °C, the reaction time is 6 - 8 h, the pH is adjusted to 7 - 8 with ammonia water, the low-temperature stirring time is 30 - 45 min, washed with distilled water, the drying temperature is 70 - 80 °C, and then washed with a mixed solution of ethyl acetate and petroleum ether, and recrystallized with ethyl acetate.

[0016] Preferably, in Q3, the dosage ratio of product 2, dichloromethane and boron tribromide is (0.18 - 0.29) g : (10 - 15) mL : (1.01 - 1.36) g. The low-temperature environment temperature is 0 - 1 °C, the temperature-rising reaction temperature is 25 - 28 °C, the reaction time is 2 - 5 h, pre-cooled methanol is added to quench the reaction, washed with dichloromethane, and recrystallized with absolute ethanol.

[0017] Preferably, the preparation method of the modified additive includes the following steps:

[0018] S1: Add cassava starch into a container, then add sodium silicate solution, stir evenly, activate at room temperature, then add 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, stir and mix, continue to add sodium silicate solution, seal and stand still at room temperature, heat and react, cool, wash, dry, and grind to obtain powder 1;

[0019] S2: Add powder 1, absolute ethanol and deionized water into a container, stir, then add sodium chloroacetate, continue to stir and then add sodium hydroxide, carry out condensation reflux to obtain a starch solution, raise the temperature for reaction, after the reaction ends, cool, adjust the pH, carry out suction filtration, wash, dry, and crush to obtain the modified additive.

[0020] In the above process, 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride undergoes an esterification reaction with cassava starch. When the ring of the acid anhydride is opened, one end combines with the free hydroxyl group of the cassava starch molecule to form an ester group, obtaining powder 1. Subsequently, powder 1 and sodium chloroacetate undergo a substitution reaction under alkaline conditions to prepare the modified additive.

[0021] Preferably, in S1, the dosage ratio of cassava starch and 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride is (10 - 18) g : (4 - 6) g, the room-temperature activation time is 60 - 75 min, the sealed standing time is 3 - 5 h, the heating reaction temperature is 50 - 70 °C, the reaction time is 2 - 4 h, and washed with 85 vt% ethanol.

[0022] Preferably, in S2, the dosage ratio of powder 1, absolute ethanol, deionized water, sodium chloroacetate and sodium hydroxide is (50 - 75) g : (200 - 220) mL : (12 - 15) mL : (15 - 22) g : (4.5 - 7.2) g, the stirring speed is 300 - 500 rpm, the continuous stirring time is 10 - 15 min, the temperature for the temperature-raising reaction is 60 - 75 °C, the reaction time is 2 - 4 h, the pH is adjusted to 7.5 - 8 with glacial acetic acid, and washing is carried out with 95 vt% ethanol.

[0023] Preferably, a preparation method of the degradable modified plastic particles includes the following steps:

[0024] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, they are successively added to a high-speed mixer for mixing to obtain a premix.

[0025] Step 2: The filtered tributyl acetylcitrate is added to the premix, mixed and stirred, then dodecyltrimethoxysilane is added in batches, and finally an organic antibacterial agent and a modification additive are added, mixed, cured, melt-blended and extruded, pelletized, and post-cured to obtain degradable modified plastic particles.

[0026] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0027] The present invention first prepares an organic antibacterial agent from p-methoxybenzaldehyde, piperidine, 2,3-butanedione, p-fluorobenzaldehyde and boron tribromide. Subsequently, a modification additive is prepared from cassava starch, 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, sodium chloroacetate and sodium hydroxide. During the preparation process of the degradable modified plastic particles, adding the organic antibacterial agent and the modification additive can effectively improve the antibacterial performance, mechanical properties and degradation performance of the plastic particles. The fluorine atoms contained in the organic antibacterial agent can be adsorbed on the positively charged peptidoglycan layer on the surface of bacteria through electrostatic interaction, destroying the cell membrane. The conjugated double bond structure contained can undergo π-π stacking with DNA bases, blocking DNA replication and interfering with metabolism, thereby achieving the antibacterial effect; the modification additive can react with the plastic particle raw materials to form dynamic hydrogen bonds, dissipate energy through bond breakage-recombination, improve the mechanical properties, and the presence of the modification additive can improve the wettability of the plastic particle surface, promote the penetration of hydrolase, and accelerate degradation. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1: This example discloses a preparation method of an organic antibacterial agent, including the following steps:

[0030] Q1: Add 13.13 g of p-methoxybenzaldehyde, 4.43 g of hexahydropyridine, and 40 mL of methanol into a container, stir to dissolve, slowly heat up to 50 °C, and then use a constant pressure dropping funnel to dropwise add a mixed solution of 4.37 g of 2,3-butanedione and 80 mL of methanol. Control the dropping time to be 4 h. After the dropping is completed, continue to react for 5 h. After the reaction is completed, cool, carry out vacuum filtration, wash with methanol, dry, carry out recrystallization with anhydrous ethanol and N,N-dimethylformamide to obtain Product 1;

[0031] Q2: Add 1.03 g of Product 1, 0.62 g of p-fluorobenzaldehyde, 2.28 g of ammonium acetate, and 32 mL of glacial acetic acid into a container, heat and react in an oil bath at 120 °C for 8 h. After the reaction is completed, cool, carry out rotary evaporation under reduced pressure, filter, add the filtrate into ice water, adjust the pH = 7 with ammonia water, stir at low temperature for 45 min, continue to carry out vacuum filtration, wash with distilled water, dry at 80 °C, and then wash with a mixed solution of ethyl acetate and petroleum ether, carry out recrystallization with ethyl acetate to obtain Product 2;

[0032] Q3: Under a low-temperature environment of 1 °C, add 0.23 g of Product 2 into a container containing 12.5 mL of dichloromethane, and then slowly dropwise add 1.18 g of boron tribromide. After the dropping is completed, heat up to 28 °C and react for 5 h. After the reaction is completed, add pre-cooled methanol to quench the reaction, carry out concentration under reduced pressure, wash with dichloromethane, carry out recrystallization with anhydrous ethanol, dry to obtain the organic antibacterial agent.

[0033] This example discloses a preparation method of a modified additive, including the following steps:

[0034] S1: Add 14 g of tapioca starch into a container, then add 8 g of sodium silicate solution, stir evenly, activate at room temperature for 60 min, then add 5 g of 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, stir and mix, continue to add 0.15 g of sodium silicate solution, seal and stand at room temperature for 5 h, heat and react at 60 °C for 4 h, cool, wash with 85 vt% ethanol, dry, and grind to obtain Powder 1;

[0035] S2: Add 62.5 g of powder 1, 210 mL of absolute ethanol, and 13.5 mL of deionized water into a container, stir at 500 rpm, then add 17 g of sodium chloroacetate, continue stirring for 15 min, then add 5.8 g of sodium hydroxide, carry out condensation reflux to obtain a starch solution, raise the temperature to 60 °C and react for 4 h. After the reaction is completed, cool it, adjust the pH to 7.5 with glacial acetic acid, carry out suction filtration, wash it with 95 vt% ethanol, dry it, and pulverize it to obtain a modified additive.

[0036] This example discloses a degradable modified plastic particle, which is composed of the following components in parts by weight: 40 parts of polylactic acid, 4 parts of polyhydroxybutyrate, 30 parts of polybutylene adipate / terephthalate, 7.5 parts of tributyl acetylcitrate, 3 parts of dodecyltrimethoxysilane, 5 parts of organic antibacterial agent, and 15 parts of modified additive.

[0037] This example discloses a preparation method of a degradable modified plastic particle, which includes the following steps:

[0038] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, add them into a high-speed mixer in sequence for mixing to obtain a premix.

[0039] Step 2: Add the filtered tributyl acetylcitrate into the premix, mix and stir, then add dodecyltrimethoxysilane in batches, and finally add the organic antibacterial agent and the modified additive, mix, cure, carry out melt blending and extrusion, pelletize, and post-cure to obtain a degradable modified plastic particle.

[0040] Example 2: This example discloses a preparation method of an organic antibacterial agent, which includes the following steps:

[0041] Q1: Add 10 g of p-methoxybenzaldehyde, 3.82 g of hexahydropyridine, and 40 mL of methanol into a container, stir to dissolve, slowly raise the temperature to 50 °C, then use a constant pressure dropping funnel to dropwise add a mixed solution of 4.11 g of 2,3-butanedione and 80 mL of methanol, control the dropping time to be 4 h. After the dropping is completed, continue the reaction for 5 h. After the reaction is completed, cool it, carry out vacuum filtration, wash it with methanol, dry it, carry out recrystallization with absolute ethanol and N,N-dimethylformamide to obtain product 1.

[0042] Q2: Add 0.88 g of product 1, 0.55 g of p-fluorobenzaldehyde, 2.11 g of ammonium acetate, and 25 mL of glacial acetic acid into a container, heat and react in an oil bath at 120 °C for 8 h. After the reaction is completed, cool it, carry out rotary evaporation under reduced pressure, carry out suction filtration, add the filtrate into ice water, adjust the pH to 7 with ammonia water, stir at low temperature for 45 min, continue vacuum filtration, wash it with distilled water, dry it at 80 °C, then wash it with a mixed solution of ethyl acetate and petroleum ether, and carry out recrystallization with ethyl acetate to obtain product 2.

[0043] Q3: At a low temperature of 1 °C, 0.18 g of product 2 was added to a container containing 10 mL of dichloromethane, and then 1.01 g of boron tribromide was slowly added dropwise. After the addition was complete, the temperature was raised to 28 °C and the reaction was carried out for 5 h. After the reaction was completed, pre-cooled methanol was added to quench the reaction, and the mixture was concentrated under reduced pressure, washed with dichloromethane, recrystallized with absolute ethanol, and dried to obtain an organic antibacterial agent.

[0044] This example discloses a preparation method of a modified additive, which includes the following steps:

[0045] S1: 10 g of tapioca starch was added to a container, and then 8 g of sodium silicate solution was added. After stirring evenly, it was activated at room temperature for 60 min, and then 4 g of 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride was added. After stirring and mixing, 0.15 g of sodium silicate solution was continuously added, and it was sealed and allowed to stand at room temperature for 5 h, heated and reacted at 60 °C for 4 h, cooled, washed with 85 vt% ethanol, dried, and ground to obtain powder 1;

[0046] S2: 50 g of powder 1, 220 mL of absolute ethanol, and 12 mL of deionized water were added to a container, stirred at 500 rpm, then 15 g of sodium chloroacetate was added, and after stirring for 15 min, 4.5 g of sodium hydroxide was added, and the mixture was refluxed under condensation to obtain a starch solution. The temperature was raised to 60 °C and the reaction was carried out for 4 h. After the reaction was completed, it was cooled, and the pH was adjusted to 7.5 with glacial acetic acid, filtered by suction, washed with 95 vt% ethanol, dried, and pulverized to obtain a modified additive.

[0047] This example discloses a degradable modified plastic particle, which is composed of the following components in parts by weight: 30 parts of polylactic acid, 2 parts of polyhydroxybutyrate, 20 parts of polybutylene adipate / terephthalate, 5 parts of tributyl acetylcitrate, 2 parts of dodecyltrimethoxysilane, 2 parts of organic antibacterial agent, and 10 parts of modified additive.

[0048] This example discloses a preparation method of a degradable modified plastic particle, which includes the following steps:

[0049] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, they were successively added to a high-speed mixer for mixing to obtain a premix;

[0050] Step 2: The filtered tributyl acetylcitrate was added to the premix, mixed and stirred, then dodecyltrimethoxysilane was added in batches, and finally the organic antibacterial agent and the modified additive were added, mixed, cured, melt-blended and extruded, granulated, and post-cured to obtain degradable modified plastic particles.

[0051] Example 3: This example discloses a preparation method of an organic antibacterial agent, which includes the following steps:

[0052] Q1: Add 16.27 g of p-methoxybenzaldehyde, 4.95 g of hexahydropyridine, and 40 mL of methanol into a container, stir to dissolve, slowly heat up to 50 °C, and then use a constant pressure dropping funnel to dropwise add a mixed solution of 4.63 g of 2,3-butanedione and 80 mL of methanol. Control the dropping time to be 4 h. After the dropping is completed, continue to react for 5 h. After the reaction is completed, cool, perform vacuum filtration, wash with methanol, dry, perform recrystallization with absolute ethanol and N,N-dimethylformamide to obtain Product 1;

[0053] Q2: Add 1.25 g of Product 1, 0.79 g of p-fluorobenzaldehyde, 2.45 g of ammonium acetate, and 38 mL of glacial acetic acid into a container, heat and react in an oil bath at 120 °C for 8 h. After the reaction is completed, cool, perform rotary evaporation under reduced pressure, filter, add the filtrate into ice water, adjust the pH = 7 with ammonia water, stir at low temperature for 45 min, continue to perform vacuum filtration, wash with distilled water, dry at 80 °C, and then wash with a mixed solution of ethyl acetate and petroleum ether, perform recrystallization with ethyl acetate to obtain Product 2;

[0054] Q3: Under a low-temperature environment of 1 °C, add 0.29 g of Product 2 into a container containing 15 mL of dichloromethane, and then slowly dropwise add 1.36 g of boron tribromide. After the dropping is completed, heat up to 28 °C and react for 5 h. After the reaction is completed, add pre-cooled methanol to quench the reaction, concentrate under reduced pressure, wash with dichloromethane, perform recrystallization with absolute ethanol, dry to obtain the organic antibacterial agent.

[0055] This example discloses a preparation method of a modified additive, which includes the following steps:

[0056] S1: Add 18 g of cassava starch into a container, then add 8 g of sodium silicate solution, stir evenly, activate at room temperature for 60 min, then add 6 g of 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, stir and mix, continue to add 0.15 g of sodium silicate solution, seal and stand at room temperature for 5 h, heat and react at 60 °C for 4 h, cool, wash with 85 vt% ethanol, dry, and grind to obtain Powder 1;

[0057] S2: Add 75 g of Powder 1, 200 mL of absolute ethanol, and 15 mL of deionized water into a container, stir at 500 rpm, then add 22 g of sodium chloroacetate, continue to stir for 15 min and then add 7.2 g of sodium hydroxide, perform reflux condensation to obtain a starch solution, heat up and react at 60 °C for 4 h. After the reaction is completed, cool, adjust the pH = 7.5 with glacial acetic acid, filter, wash with 95 vt% ethanol, dry, and crush to obtain the modified additive.

[0058] This embodiment discloses a degradable modified plastic particle, which is composed of the following components in parts by weight: 50 parts of polylactic acid, 6 parts of polyhydroxybutyrate, 40 parts of polybutylene adipate / terephthalate, 10 parts of tributyl acetylcitrate, 4 parts of dodecyltrimethoxysilane, 8 parts of an organic antibacterial agent, and 20 parts of a modified additive.

[0059] This embodiment discloses a preparation method of a degradable modified plastic particle, which includes the following steps:

[0060] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, they are sequentially added to a high-speed mixer for mixing to obtain a premix.

[0061] Step 2: The filtered tributyl acetylcitrate is added to the premix, mixed and stirred, then dodecyltrimethoxysilane is added in batches, and finally the organic antibacterial agent and the modified additive are added, mixed, cured, melt-blended and extruded, pelletized, and post-cured to obtain the degradable modified plastic particle.

[0062] Example 4: This embodiment discloses a preparation method of an organic antibacterial agent, which includes the following steps:

[0063] Q1: Add 11.86 g of p-methoxybenzaldehyde, 4.21 g of hexahydropyridine, and 40 mL of methanol to a container, stir to dissolve, slowly heat up to 50 °C, and then use a constant pressure dropping funnel to dropwise add a mixed solution of 4.23 g of 2,3-butanedione and 80 mL of methanol. Control the dropping time to be 4 h. After the dropping is completed, continue the reaction for 5 h. After the reaction is completed, cool, filter under reduced pressure, wash with methanol, dry, recrystallize with absolute ethanol and N,N-dimethylformamide to obtain Product 1.

[0064] Q2: Add 0.97 g of Product 1, 0.61 g of p-fluorobenzaldehyde, 2.19 g of ammonium acetate, and 29 mL of glacial acetic acid to a container, heat and react in an oil bath at 120 °C for 8 h. After the reaction is completed, cool, rotary evaporate under reduced pressure, filter, add the filtrate to ice water, adjust the pH = 7 with ammonia water, stir at low temperature for 45 min, continue to filter under reduced pressure, wash with distilled water, dry at 80 °C, then wash with a mixed solution of ethyl acetate and petroleum ether, and recrystallize with ethyl acetate to obtain Product 2.

[0065] Q3: At a low temperature of 1 °C, add 0.19 g of Product 2 to a container containing 11 mL of dichloromethane, then slowly dropwise add 1.09 g of boron tribromide. After the dropping is completed, raise the temperature to 28 °C and react for 5 h. After the reaction is completed, add pre-cooled methanol to quench the reaction, concentrate under reduced pressure, wash with dichloromethane, recrystallize with absolute ethanol, dry to obtain the organic antibacterial agent.

[0066] This embodiment discloses a preparation method of a modified additive, which includes the following steps:

[0067] S1: Add 12 g of tapioca starch into a container, then add 8 g of sodium silicate solution. After stirring evenly, activate at room temperature for 60 min, then add 4.5 g of 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride. After stirring and mixing, continue to add 0.15 g of sodium silicate solution, seal and let stand at room temperature for 5 h, heat and react at 60 °C for 4 h, cool, wash with 85 vt% ethanol, dry, grind to obtain powder 1;

[0068] S2: Add 65 g of powder 1, 205 mL of absolute ethanol and 13 mL of deionized water into a container, stir at 500 rpm, then add 16 g of sodium chloroacetate, continue to stir for 15 min, then add 4.8 g of sodium hydroxide, carry out condensation reflux to obtain a starch solution, raise the temperature to 60 °C and react for 4 h. After the reaction is completed, cool, adjust the pH to 7.5 with glacial acetic acid, carry out suction filtration, wash with 95 vt% ethanol, dry, pulverize to obtain the modified additive.

[0069] This embodiment discloses a degradable modified plastic particle, which is composed of the following components in parts by weight: 45 parts of polylactic acid, 3 parts of polyhydroxybutyrate, 25 parts of polybutylene adipate / terephthalate, 6 parts of tributyl acetylcitrate, 2.5 parts of dodecyltrimethoxysilane, 4 parts of organic antibacterial agent, 12 parts of modified additive.

[0070] This embodiment discloses a preparation method of a degradable modified plastic particle, which includes the following steps:

[0071] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, add them into a high-speed mixer in sequence for mixing to obtain a premix;

[0072] Step 2: Add the filtered tributyl acetylcitrate into the premix, mix and stir, then add dodecyltrimethoxysilane in batches, and finally add the organic antibacterial agent and the modified additive, mix, cure, melt-blend and extrude, pelletize, and post-cure to obtain the degradable modified plastic particle.

[0073] Example 5: This embodiment discloses a preparation method of an organic antibacterial agent, which includes the following steps:

[0074] Q1: Add 14.15 g of p-methoxybenzaldehyde, 4.73 g of hexahydropyridine, and 40 mL of methanol into a container, stir to dissolve, slowly heat up to 50 °C, and then use a constant-pressure dropping funnel to dropwise add a mixed solution of 4.52 g of 2,3-butanedione and 80 mL of methanol, control the dropping time to be 4 h. After the dropping is completed, continue the reaction for 5 h. After the reaction is completed, cool, perform vacuum filtration, wash with methanol, dry, recrystallize with absolute ethanol and N,N-dimethylformamide to obtain Product 1;

[0075] Q2: Add 1.13 g of Product 1, 0.73 g of p-fluorobenzaldehyde, 2.31 g of ammonium acetate, and 31 mL of glacial acetic acid into a container, heat and react in an oil bath at 120 °C for 8 h. After the reaction is completed, cool, perform rotary evaporation under reduced pressure, filter, add the filtrate into ice water, adjust the pH = 7 with ammonia water, stir at low temperature for 45 min, continue vacuum filtration, wash with distilled water, dry at 80 °C, and then wash with a mixed solution of ethyl acetate and petroleum ether, recrystallize with ethyl acetate to obtain Product 2;

[0076] Q3: Under a low-temperature environment of 1 °C, add 0.25 g of Product 2 into a container containing 14 mL of dichloromethane, and then slowly dropwise add 1.27 g of boron tribromide. After the dropping is completed, heat up to 28 °C and react for 5 h. After the reaction is completed, add pre-cooled methanol to quench the reaction, concentrate under reduced pressure, wash with dichloromethane, recrystallize with absolute ethanol, dry to obtain the organic antibacterial agent.

[0077] This example discloses a preparation method of a modified additive, including the following steps:

[0078] S1: Add 16 g of tapioca starch into a container, then add 8 g of sodium silicate solution, stir evenly, activate at room temperature for 60 min, then add 5.5 g of 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, stir and mix, continue to add 0.15 g of sodium silicate solution, seal and stand at room temperature for 5 h, heat and react at 60 °C for 4 h, cool, wash with 85 vt% ethanol, dry, grind to obtain Powder 1;

[0079] S2: Add 70 g of Powder 1, 215 mL of absolute ethanol, and 14 mL of deionized water into a container, stir at 500 rpm, then add 21 g of sodium chloroacetate, continue to stir for 15 min and then add 6.9 g of sodium hydroxide, perform reflux condensation to obtain a starch solution, heat up and react at 60 °C for 4 h. After the reaction is completed, cool, adjust the pH = 7.5 with glacial acetic acid, filter, wash with 95 vt% ethanol, dry, and crush to obtain the modified additive.

[0080] This example discloses a degradable modified plastic particle, which is composed of the following components in parts by weight: 35 parts of polylactic acid, 5 parts of polyhydroxybutyrate, 35 parts of polybutylene adipate / terephthalate, 9 parts of tributyl acetylcitrate, 3.5 parts of dodecyltrimethoxysilane, 7 parts of organic antibacterial agent, and 18 parts of modified additive.

[0081] This example discloses a preparation method of a degradable modified plastic particle, which includes the following steps:

[0082] Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, add them to a high-speed mixer in sequence for mixing to obtain a premix.

[0083] Step 2: Add the filtered tributyl acetylcitrate to the premix, mix and stir, then add dodecyltrimethoxysilane in batches, and finally add the organic antibacterial agent and the modified additive, mix, cure, melt-blend and extrude, pelletize, and post-cure to obtain the degradable modified plastic particle.

[0084] Comparative Example 1: Compared with Example 1, in the process of preparing the degradable modified plastic particle in Comparative Example 1, no organic antibacterial agent is added, and other conditions remain unchanged.

[0085] Comparative Example 2: Compared with Example 1, in the process of preparing the degradable modified plastic particle in Comparative Example 2, no modified additive is added, and other conditions remain unchanged.

[0086] Experimental Example: Perform performance tests on the degradable modified plastic particles prepared in Examples 1-5 and Comparative Examples 1-2. Test the tensile strength and elongation at break of the samples according to ASTM D638, test the antibacterial rate of the samples according to ISO 22196, and test the degradation rate of the samples according to ISO 14855. The test results are shown in Table 1:

[0087] Table 1

[0088] Project Tensile strength / MPa Elongation at break / % Antibacterial rate / 24 h, % Degradation rate / 60 days, % Example 1 35.42 215.6 99.46 85.73 Example 2 35.27 214.8 99.41 85.58 Example 3 34.95 214.6 99.16 84.82 Example 4 34.68 215.1 99.01 85.01 Example 5 35.02 213.9 99.32 84.52 Comparative example 1 34.73 213.6 38.94 84.23 Comparative example 2 22.95 137.3 99.08 45.62

[0089] It can be seen from the test results in Table 1 that the degradable modified plastic particles prepared in Examples 1-5 of the present invention have excellent mechanical properties, antibacterial properties, and degradation properties. By comparing Comparative Example 1 with Examples 1-5, it can be known that adding an organic antibacterial agent can effectively improve the antibacterial property of the degradable modified plastic particle; by comparing Comparative Example 2 with Examples 1-5, it can be known that adding a modified additive can effectively improve the mechanical properties and degradation properties of the degradable modified plastic particle.

[0090] As mentioned above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent replacements or changes, shall be covered by the protection scope of the present invention.

[0091] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific embodiments. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A degradable modified plastic particle, characterized in that, It consists of the following components in parts by weight: 30-50 parts of polylactic acid, 2-6 parts of polyhydroxybutyrate, 20-40 parts of polybutylene adipate / terephthalate, 5-10 parts of tributyl acetylcitrate, 2-4 parts of dodecyltrimethoxysilane, 2-8 parts of organic antibacterial agent, 10-20 parts of modified additive. Among them, the organic antibacterial agent is mainly prepared from p-methoxybenzaldehyde, hexahydropyridine, 2,3-butanedione, p-fluorobenzaldehyde and boron tribromide as raw materials, and the modified additive is mainly prepared from cassava starch, 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, sodium chloroacetate and sodium hydroxide as raw materials.

2. The degradable modified plastic particles according to claim 1, wherein, The preparation method of the organic antibacterial agent includes the following steps: Q1: Add p-methoxybenzaldehyde, hexahydropyridine and methanol into a container, stir to dissolve, slowly heat up, and then use a constant pressure dropping funnel to dropwise add a mixed solution of 2,3-butanedione and methanol, control the dropping time. After dropping, continue the reaction. After the reaction is completed, cool, carry out vacuum filtration, wash, dry, and recrystallize to obtain Product 1; Q2: Add Product 1, p-fluorobenzaldehyde, ammonium acetate and glacial acetic acid into a container, heat and react in an oil bath. After the reaction is completed, cool, carry out rotary evaporation under reduced pressure, filter, add the filtrate into ice water, adjust the pH, stir at low temperature, continue vacuum filtration, wash, dry, wash, and recrystallize to obtain Product 2; Q3: Under a low-temperature environment, add Product 2 into a container containing dichloromethane, and then slowly dropwise add boron tribromide. After dropping, heat up and react. After the reaction is completed, quench the reaction, concentrate under reduced pressure, wash, recrystallize, dry to obtain the organic antibacterial agent.

3. The degradable modified plastic particles according to claim 2, characterized in that, In Q1, the dosage ratio of p-methoxybenzaldehyde, hexahydropyridine and 2,3-butanedione is (10-16.27) g: (3.82-4.95) g: (4.11-4.63) g, heat up to 50-55 °C, the dropping time is 4-6 h, the continued reaction time is 3-5 h, wash with methanol, and recrystallize with absolute ethanol and N,N-dimethylformamide.

4. A degradable modified plastic particle according to claim 2, characterized in that, In Q2, the dosage ratio of Product 1, p-fluorobenzaldehyde, ammonium acetate and glacial acetic acid is (0.88-1.25) g: (0.55-0.79) g: (2.11-2.45) g: (25-38) mL, the heating reaction temperature is 115-120 °C, the reaction time is 6-8 h, adjust the pH = 7-8 with ammonia water, the low-temperature stirring time is 30-45 min, wash with distilled water, the drying temperature is 70-80 °C, then wash with a mixed solution of ethyl acetate and petroleum ether, and recrystallize with ethyl acetate.

5. The degradable modified plastic particles according to claim 2, characterized in that, In Q3, the dosage ratio of Product 2, dichloromethane and boron tribromide is (0.18-0.29) g: (10-15) mL: (1.01-1.36) g, the low-temperature environment temperature is 0-1 °C, the heating reaction temperature is 25-28 °C, the reaction time is 2-5 h, add pre-cooled methanol to quench the reaction, wash with dichloromethane, and recrystallize with absolute ethanol.

6. A degradable modified plastic particle according to claim 1, wherein, The preparation method of the modified additive includes the following steps: S1: Add cassava starch into a container, then add sodium silicate solution. After stirring evenly, activate at room temperature, then add 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride. After stirring and mixing, continue to add sodium silicate solution, seal and let stand at room temperature, heat for reaction, cool, wash, dry, and grind to obtain Powder 1; S2: Add Powder 1, absolute ethanol, and deionized water into a container, stir, then add sodium chloroacetate, continue to stir and then add sodium hydroxide, carry out condensation reflux to obtain a starch solution, raise the temperature for reaction, after the reaction ends, cool, adjust the pH, carry out suction filtration, wash, dry, and crush to obtain a modified additive.

7. The degradable modified plastic particles according to claim 6, characterized in that, In the above S1, the dosage ratio of cassava starch to 4-(4-methyl-3-pentenyl)-4-cyclohexene-1,2-dicarboxylic anhydride is (10 - 18) g : (4 - 6) g, the activation time at room temperature is 60 - 75 min, the sealing and standing time is 3 - 5 h, the heating reaction temperature is 50 - 70 °C, the reaction time is 2 - 4 h, and wash with 85 vt% ethanol.

8. A degradable modified plastic particle according to claim 6, wherein, In the above S2, the dosage ratio of Powder 1, absolute ethanol, deionized water, sodium chloroacetate, and sodium hydroxide is (50 - 75) g : (200 - 220) mL : (12 - 15) mL : (15 - 22) g : (4.5 - 7.2) g.

9. A degradable modified plastic according to claim 6, characterized in that, In the above S2, the stirring speed is 300 - 500 rpm, the continuous stirring time is 10 - 15 min, the temperature-raising reaction temperature is 60 - 75 °C, the reaction time is 2 - 4 h, adjust the pH = 7.5 - 8 with glacial acetic acid, and wash with 95 vt% ethanol.

10. The preparation method of a degradable modified plastic particle according to any one of claims 1-9, characterized in that, It includes the following steps: Step 1: After drying polylactic acid, polyhydroxybutyrate, and polybutylene adipate / terephthalate, add them into a high-speed mixer in sequence for mixing to obtain a premix; Step 2: Add the filtered tributyl acetylcitrate into the premix, mix and stir, then add dodecyltrimethoxysilane in batches, finally add an organic antibacterial agent and a modified additive, mix, cure, carry out melt blending and extrusion, granulate, and post-cure to obtain degradable modified plastic particles.

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