Environment-friendly degradable plastic and preparation method thereof

Abstract

The invention belongs to the technical field of degradable plastics, and particularly relates to an environment-friendly degradable plastic and a preparation method thereof. The PBS / PBS composite material is prepared from the following components in parts by weight: 30 to 50 parts of PBS; 70 to 90 parts of polylactic acid (PLA); cTAB (cetyltrimethyl ammonium bromide) modified CuCexFe (1-x)-LDH (layered double hydroxide), wherein x is equal to 0.02 to 0.04 to 8 to 12 parts; 3-7 parts of sorbic acid; and 3-5 parts of a chain extender. According to the environment-friendly degradable plastic, the antibacterial property of the plastic can be improved by adding the hydrotalcite-like compound, the antibacterial property of the plastic can be further improved by adding Ce and modifying CTAB, and the antibacterial property of the environment-friendly degradable plastic is more excellent by compounding the hydrotalcite-like compound and sorbic acid. The environment-friendly degradable plastic prepared by the invention has good mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of degradable plastics, and more specifically, relates to an environmentally friendly degradable plastic and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA), also known as polylactide, is mainly made from renewable plant resources such as corn, wheat, and cassava. Starch is extracted from them and lactic acid is made through a fermentation process, and then converted into PLA through chemical synthesis. Its raw material source is sufficient and renewable, making it an ideal green polymer material. However, PLA still has many disadvantages, such as poor mechanical properties and antibacterial properties, which limit its application in some fields.

[0003] CN117924889A discloses an antibacterial and environmentally friendly degradable plastic bag and a preparation method thereof. The plastic bag is made of PBAT resin, a loaded antibacterial additive, a resin-type functional auxiliary material, a chain extender, an antioxidant and a stabilizer as raw materials through mixing, granulation, film blowing and punching processes. The addition of the loaded antibacterial additive can produce a sustained-release antibacterial effect, giving the plastic bag excellent antibacterial properties, while giving full play to the advantages of sericite powder to effectively improve the mechanical properties of the plastic bag. The addition of the resin-type functional auxiliary material can form a super-hydrophobic surface on the plastic bag. On the one hand, the presence of the super-hydrophobic surface can make it difficult for moisture to adhere to the surface of the plastic bag, avoiding the formation of a humid environment required for bacterial growth on the surface of the plastic bag. On the other hand, the super-hydrophobic surface can also produce a self-cleaning effect, avoiding the plastic bag from being contaminated with moisture and oil stains during food packaging, which affects the packaging effect of the plastic bag.

[0004] CN117343372A discloses an antibacterial plastic and a preparation method thereof. Starch and polylactic acid are selected as substrate raw materials, and polyvinyl alcohol fiber is used as a toughening agent; starch is gradually chemically modified, first by amination and then by long-chain quaternary ammonium salt modification; arginine is grafted onto chitosan through an acylation reaction, and nano titanium dioxide is generated in situ on the arginized chitosan using arginized chitosan as a membrane plate and isopropyl titanate as a titanium source; a layer of antibacterial coating that can form a self-repairing antibacterial surface is coated on the surface of a degradable substrate, and a reversible enamine covalent bond is generated by using side chain acetoacetate in a polyacrylate resin containing sulfonyl betaine, quaternary ammonium salt starch rich in amino groups and composite titanium dioxide by controlling their mass ratio, thereby obtaining a high-strength, self-cleaning, antibacterial and self-repairing surface.

[0005] CN117050485A discloses an antibacterial degradable plastic for food packaging and a preparation method thereof. An antibacterial degradable plastic for food packaging, comprising the following raw materials in parts by weight: 6570 parts of polybutylene succinate resin, 2530 parts of modified starch, 15-18 parts of modified bamboo charcoal fiber, 1012 parts of organic montmorillonite, 36 parts of plasticizer, 0.5-1.0 parts of antioxidant, 6-10 parts of monoglyceride, 13 parts of antibacterial agent, wherein the antibacterial agent is a composition of soluble glass silver antibacterial agent, polyhexamethylene guanidine hydrochloride, and nisin in a mass ratio of 1:3-5:2-4. The degradable plastic of the present application has degradability. It has excellent antibacterial performance, good heat resistance, high mechanical strength, good processing performance and other characteristics, can adapt to different environments and application requirements, and improve the safety and sustainable development of food packaging.

[0006] The antibacterial properties of plastics can be improved by adding antibacterial materials, and the mechanical properties of plastics can also be improved. LDHs have certain antibacterial properties and can be used as antibacterial agents. They can be used in plastics to improve the antibacterial properties of plastics. Sorbic acid has high antibacterial properties and inhibits the growth and reproduction of molds. It mainly inhibits the dehydrogenase system in microorganisms, thereby inhibiting the growth of microorganisms and playing an antiseptic role. It has an inhibitory effect on bacteria, molds, and yeasts. In the prior art, LDHs and sorbic acid are not used in combination in plastics to improve the antibacterial properties of plastics. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the prior art and provide an environmentally friendly degradable plastic and a preparation method thereof. The following components are included by weight: 30 to 50 parts of polybutylene succinate PBS; 70 to 90 parts of polylactic acid PLA; CTAB-modified CuCe x Fe (1-x) -LDH, wherein x=0.02-0.048-12 parts; sorbic acid 3-7 parts; chain extender 3-5 parts. The present invention can improve the antibacterial properties of plastics by adding hydrotalcite-like substances, further improve the antibacterial properties of plastics by adding Ce and modifying CTAB, and make the antibacterial properties of environmentally friendly degradable plastics more excellent by compounding hydrotalcite-like substances and sorbic acid. The environmentally friendly degradable plastics prepared by the present invention have good mechanical properties.

[0008] The purpose of the invention is to provide an environmentally friendly and degradable plastic.

[0009] Another object of the present invention is to provide a method for preparing environmentally friendly and degradable plastics.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] An environmentally friendly degradable plastic, comprising the following components by weight:

[0012] 30-50 parts of polybutylene succinate PBS;

[0013] Polylactic acid PLA 70-90 parts;

[0014] CTAB modified CuCe x Fe (1-x) -LDH, wherein x = 0.02 to 0.04 8 to 12 parts;

[0015] 3-7 parts of sorbic acid;

[0016] 3 to 5 parts of chain extender.

[0017] Preferably, the weight average molecular weight of the PBS is 100,000 to 160,000.

[0018] Preferably, the weight average molecular weight of the PLA is 140,000 to 180,000.

[0019] Preferably, the chain extender is dibenzoyl oxide.

[0020] In the present invention, the preferred technical solution is that the cetyltrimethylammonium bromide (CTAB) modified CuCe x Fe (1-x) The preparation method of -LDH is as follows:

[0021] (1) Add copper salt, cerium salt and iron salt to deionized water, and ultrasonically disperse for 20 to 40 minutes to obtain a dispersion; then add a certain amount of urea to the dispersion, stir evenly, and then heat to a certain temperature for hydrothermal reaction for a certain time, filter, wash, and dry to constant weight to obtain CuCe x Fe (1-x) -LDH;

[0022] (2) The CuCe obtained in step (1) x Fe (1-x) -LDH and CTAB were ultrasonically dispersed in deionized water, then stirred at a certain temperature for a certain time, filtered, and dried to constant weight to obtain CTAB-modified CuCe x Fe (1-x) -LDH.

[0023] Preferably, in step (1), the molar ratio of the copper salt, the cerium salt and the iron salt is 3:x:(1-x), wherein x=0.02-0.04; the copper salt is at least one of copper nitrate, copper chloride and copper acetate; the cerium salt is at least one of cerium nitrate, cerium chloride and cerium acetate; and the iron salt is at least one of ferric nitrate, ferric chloride and ferric acetate.

[0024] Preferably, in step (1), the molar ratio of urea to copper salt is 3-4:1; the hydrothermal reaction conditions are 90-110° C. for 10-20 h; and the drying temperature is 80-100° C.

[0025] Preferably, in step (2), the CuCe x Fe (1-x) -The mass ratio of LDH and CTAB is 100:0.6~1.2.

[0026] Preferably, the stirring reaction is carried out at 50-90°C for 1-3 hours, and the drying temperature is 80-100°C.

[0027] Based on the above-mentioned method for preparing an environmentally friendly and degradable plastic, the preparation method comprises the following steps:

[0028] The components are mixed uniformly according to the proportion, and then added into a twin-screw extruder, and the parameters are set as follows: screw speed 180-260rpm, heating temperatures of zones 1-5 are as follows: 145-155°C, 155-160°C, 160-170°C, 165-175°C, 170-180°C; granulation, and then drying the granulated material at 70-90°C for 4-8h to obtain a film blowing material, and then feeding it into a film blowing machine for film blowing, and the parameters are set as follows: screw speed 200-300rpm, heating temperatures of zones 1-5 are as follows: 145-155°C, 150-160°C, 155-165°C, 160-170°C, 165-175°C, and traction speed 8-10m / min.

[0029] The present invention has the following beneficial effects:

[0030] By adopting hydrothermal method to prepare hydrotalcite-like materials, by doping Ce and modifying CTAB, the antibacterial property of hydrotalcite-like materials can be improved, and the quaternary ammonium salt of the present application has antibacterial property, CTAB can improve the specific surface area of ​​hydrotalcite-like materials, further improve the antibacterial property of hydrotalcite-like materials, and by adding an appropriate amount of hydrotalcite-like materials, the mechanical properties of plastics can be improved, and by adding sorbic acid, the combination of sorbic acid and hydrotalcite-like materials can significantly improve the antibacterial property of plastics. The environmentally friendly and degradable plastic prepared by the present invention has excellent antibacterial property, and also has certain mechanical properties, and has good application prospects. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0032] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0033] Example 1

[0034] An environmentally friendly degradable plastic, comprising the following components by weight:

[0035] 40 parts of polybutylene succinate PBS; the weight average molecular weight of the PBS is 140,000;

[0036] 80 parts of polylactic acid PLA; the weight average molecular weight of the PLA is 160,000;

[0037] CTAB modified CuCe 0.03 Fe 0.97 -LDH 10 parts;

[0038] 5 parts of sorbic acid;

[0039] 4 parts of chain extender; the chain extender is dibenzoyl oxide.

[0040] CTAB modified CuCe 0.03 Fe 0.97 The preparation method of -LDH is as follows:

[0041] (1) 3 mol of copper nitrate, 0.03 mol of cerium chloride and 0.97 mol of ferric acetate were added to 200 mL of deionized water and ultrasonically dispersed for 30 min to obtain a dispersion; then 10.5 mol of urea was added to the dispersion, stirred evenly, and then heated to 100° C. for hydrothermal reaction for 16 h, filtered, washed, and dried at 90° C. to constant weight to obtain CuCe 0.03 Fe 0.97 -LDH;

[0042] (2) 100 g of CuCe obtained in step (1) 0.03 Fe 0.97 -LDH and 1 g CTAB were ultrasonically dispersed in 250 mL deionized water, then stirred at 70 °C for 2 h, filtered, and dried at 90 °C to constant weight to obtain CTAB-modified CuCe 0.03 Fe 0.97 -LDH.

[0043] A method for preparing an environmentally friendly and degradable plastic comprises the following steps:

[0044] The components are mixed evenly according to the proportion and added into a twin-screw extruder, and the parameters are set as follows: screw speed 220rpm, heating temperatures of zones 1-5 are as follows: 150°C, 158°C, 165°C, 170°C, 175°C; granulation, and then the granulated material is dried at 80°C for 6h to obtain a film blowing material, which is then put into a film blowing machine for blow molding into a film, and the parameters are set as follows: screw speed 250rpm, heating temperatures of zones 1-5 are as follows: 150°C, 155°C, 160°C, 165°C, 170°C, and a traction speed of 90m / min.

[0045] Example 2

[0046] An environmentally friendly degradable plastic, comprising the following components by weight:

[0047] 50 parts of polybutylene succinate PBS; the weight average molecular weight of the PBS is 160,000;

[0048] 70 parts of polylactic acid PLA; the weight average molecular weight of the PLA is 140,000;

[0049] CTAB modified CuCe 0.04 Fe 0.96 -LDH 12 parts;

[0050] 3 parts of sorbic acid;

[0051] 5 parts of chain extender; the chain extender is dibenzoyl oxide.

[0052] CTAB modified CuCe 0.04 Fe 0.96 The preparation method of -LDH is as follows:

[0053] (1) 3 mol of copper chloride, 0.04 mol of cerium acetate and 0.96 mol of ferric nitrate were added to 200 mL of deionized water and ultrasonically dispersed for 40 min to obtain a dispersion; then 12 mol of urea was added to the dispersion, stirred evenly, and then heated to 110° C. for hydrothermal reaction for 10 h, filtered, washed, and dried at 100° C. to constant weight to obtain CuCe 0.04 Fe 0.96 -LDH;

[0054] (2) 100 g of CuCe obtained in step (1) 0.04 Fe 0.96 -LDH and 1.2 g CTAB were ultrasonically dispersed in 250 mL deionized water, and then stirred at 90 °C for 1 h, filtered, and dried at 100 °C to constant weight to obtain CTAB-modified CuCe 0.04 Fe 0.96 -LDH.

[0055] A method for preparing an environmentally friendly and degradable plastic comprises the following steps:

[0056] The components are mixed evenly according to the ratio, and then added into a twin-screw extruder, and the parameters are set as follows: screw speed 260rpm, heating temperatures of zones 1-5 are as follows: 155°C, 155°C, 170°C, 175°C, 180°C; granulation, and then the granulated material is dried at 90°C for 4h to obtain a film blowing material, and then put into a film blowing machine for blow molding into a film, and the parameters are set as follows: screw speed 300rpm, heating temperatures of zones 1-5 are as follows: 155°C, 160°C, 165°C, 170°C, 175°C, and traction speed 10m / min.

[0057] Example 3

[0058] An environmentally friendly degradable plastic, comprising the following components by weight:

[0059] 30 parts of polybutylene succinate PBS; the weight average molecular weight of the PBS is 100,000;

[0060] 90 parts of polylactic acid PLA; the weight average molecular weight of the PLA is 180,000;

[0061] CTAB modified CuCe 0.02 Fe 0.98 - 8 parts of LDH;

[0062] 7 parts of sorbic acid;

[0063] 3 parts of chain extender; the chain extender is dibenzoyl oxide.

[0064] CTAB modified CuCe 0.02 Fe 0.98 The preparation method of -LDH is as follows:

[0065] (1) 3 mol of copper acetate, 0.02 mol of cerium nitrate and 0.98 mol of ferric chloride were added to 200 mL of deionized water and ultrasonically dispersed for 20 min to obtain a dispersion; then 9 mol of urea was added to the dispersion, stirred evenly, and then heated to 90°C for hydrothermal reaction for 20 h, filtered, washed, and dried at 80°C to constant weight to obtain CuCe 0.02 Fe 0.98 -LDH;

[0066] (2) 100 g of CuCe obtained in step (1) 0.02 Fe 0.98 -LDH and 0.6 g CTAB were ultrasonically dispersed in 250 mL deionized water, then stirred at 50 °C for 3 h, filtered, and dried at 80 °C to constant weight to obtain CTAB-modified CuCe 0.02 Fe 0.98-LDH.

[0067] A method for preparing an environmentally friendly and degradable plastic comprises the following steps:

[0068] The components are mixed evenly according to the proportion and added into a twin-screw extruder, and the parameters are set as follows: screw speed of 180 rpm, heating temperatures of zones 1-5 are as follows: 145°C, 160°C, 160°C, 165°C, 170°C; granulation, and then the granulated material is dried at 70°C for 8h to obtain a film blowing material, which is then put into a film blowing machine for blow molding into a film, and the parameters are set as follows: screw speed of 200 rpm, heating temperatures of zones 1-5 are as follows: 145°C, 150°C, 155°C, 160°C, 165°C, and a traction speed of 8m / min.

[0069] Comparative Example 1

[0070] The difference between Comparative Example 1 and Example 1 is that an equal amount of CTAB-modified CuFe-LDH is used to replace CTAB-modified CuCe 0.04 Fe 0.96 -LDH;

[0071] The preparation method of the CTAB-modified CuFe-LDH is as follows:

[0072] (1) 3 mol of copper nitrate and 1 mol of ferric acetate were added to 200 mL of deionized water, and ultrasonically dispersed for 30 min to obtain a dispersion; then 10.5 mol of urea was added to the dispersion, stirred evenly, and then heated to 100° C. for hydrothermal reaction for 16 h, filtered, washed, and dried at 90° C. to constant weight to obtain CuFe-LDH;

[0073] (2) 100 g of the CuFe-LDH obtained in step (1) and 1 g of CTAB were ultrasonically dispersed in 250 mL of deionized water, and then stirred at 70° C. for 2 h, filtered, and dried at 90° C. to constant weight to obtain CTAB-modified CuFe-LDH.

[0074] Comparative Example 2

[0075] The difference between Comparative Example 2 and Example 1 is that the same amount of CuCe 0.04 Fe 0.96 -LDH replaces CTAB modified CuCe 0.04 Fe 0.96 -LDH.

[0076] The CuCe 0.04 Fe 0.96 The preparation method of -LDH is as follows:

[0077] 3 mol of copper chloride, 0.04 mol of cerium acetate and 0.96 mol of ferric nitrate were added to 200 mL of deionized water and ultrasonically dispersed for 40 min to obtain a dispersion; then 12 mol of urea was added to the above dispersion, stirred evenly, and then heated to 110°C for hydrothermal reaction for 10 h, filtered, washed, and dried at 100°C to constant weight to obtain CuCe 0.04 Fe 0.96 -LDH.

[0078] Comparative Example 3

[0079] The difference between Comparative Example 3 and Example 1 is that the same amount of CTAB-modified CuCe 0.03 Fe 0.97 -LDH replaces sorbic acid.

[0080] The relevant properties of Examples 1-3 and Comparative Examples 1-3 were tested. The specific test results are shown in Table 1, where:

[0081] Tensile strength (MPa): GB / T 1040-2006;

[0082] Antibacterial properties: QB / T 2591-2003

[0083] Table 1:

[0084]

[0085] As can be seen from Table 1, by comparing Example 1 with Comparative Example 1, it can be seen that the antibacterial properties of the film are significantly improved by doping Ce during the preparation process of the present invention. By comparing Example 1 with Comparative Example 2, it can be seen that CTAB modification is similar to hydrotalcite, which can not only significantly improve the antibacterial properties, but also improve the tensile strength. By comparing Example 1 with Comparative Example 3, it can be seen that CTAB-modified CuCe 0.04 Fe 0.96 -LDH and sorbic acid have a synergistic effect on each other, jointly promoting the improvement of antibacterial properties.

[0086] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An environmentally friendly degradable plastic, characterized by: By weight, it includes the following components: 30-50 parts of polybutylene succinate PBS; Polylactic acid PLA 70-90 parts; CTAB modified CuCe x Fe (1-x) -LDH, wherein x = 0.02 to 0.04 8 to 12 parts; 3-7 parts of sorbic acid; 3 to 5 parts of chain extender.

2. The environmentally friendly degradable plastic according to claim 1, characterized in that: The weight average molecular weight of the PBS is 100,000 to 160,000.

3. The environmentally friendly degradable plastic according to claim 1, characterized in that: The weight average molecular weight of the PLA is 140,000 to 180,000.

4. The environmentally friendly degradable plastic according to claim 1, characterized in that: The chain extender is dibenzoyl oxide.

5. The environmentally friendly degradable plastic according to claim 1, characterized in that: The CTAB-modified CuCe x Fe (1-x) The preparation method of -LDH is as follows: (1) Add copper salt, cerium salt and iron salt to deionized water, and ultrasonically disperse for 20 to 40 minutes to obtain a dispersion; then add a certain amount of urea to the dispersion, stir evenly, and then heat to a certain temperature for hydrothermal reaction for a certain time, filter, wash, and dry to constant weight to obtain CuCe x Fe (1-x) -LDH; (2) The CuCe obtained in step (1) x Fe (1-x) -LDH and CTAB were ultrasonically dispersed in deionized water, then stirred at a certain temperature for a certain time, filtered, and dried to constant weight to obtain CTAB-modified CuCe x Fe (1-x) -LDH.

6. The environmentally friendly degradable plastic according to claim 5, characterized in that: In step (1), the molar ratio of the copper salt, the cerium salt and the iron salt is 3:x:(1-x), wherein x=0.02-0.04; the copper salt is at least one of copper nitrate, copper chloride and copper acetate; the cerium salt is at least one of cerium nitrate, cerium chloride and cerium acetate; and the iron salt is at least one of ferric nitrate, ferric chloride and ferric acetate.

7. The environmentally friendly degradable plastic according to claim 5, characterized in that: In step (1), the molar ratio of urea to copper salt is 3-4:1; the hydrothermal reaction conditions are 90-110° C. for 10-20 hours; and the drying temperature is 80-100° C.

8. The environmentally friendly degradable plastic according to claim 5, characterized in that: In step (2), the CuCe x Fe (1-x) -The mass ratio of LDH and CTAB is 100:0.6~1.

2.

9. The environmentally friendly degradable plastic according to claim 5, characterized in that: In step (2), the stirring reaction is carried out at 50-90°C for 1-3 hours, and the drying temperature is 80-100°C.

10. A method for preparing an environmentally friendly and degradable plastic according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: The components are mixed uniformly according to the proportion, and then added into a twin-screw extruder, and the parameters are set as follows: screw speed 180-260rpm, heating temperatures of zones 1-5 are as follows: 145-155°C, 155-160°C, 160-170°C, 165-175°C, 170-180°C; granulation, and then drying the granulated material at 70-90°C for 4-8h to obtain a film blowing material, and then feeding it into a film blowing machine for film blowing, and the parameters are set as follows: screw speed 200-300rpm, heating temperatures of zones 1-5 are as follows: 145-155°C, 150-160°C, 155-165°C, 160-170°C, 165-175°C, and traction speed 8-10m / min.

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