PBAT / PLA antioxidant composite film and preparation method thereof

Abstract

The invention provides a PBAT / PLA antioxidant composite film and a preparation method thereof. The PBAT / PLA antioxidant composite film comprises the following raw materials in percentage by mass: 55-85% of PBAT resin; 5-25% of PLA resin; 0.1-3% of an interface compatibilizer; and the balance of auxiliaries. According to the PBAT / PLA antioxidant composite film disclosed by the invention, the interfacial compatibilizer is added, and phenolic hydroxyl groups at two ends of curcumin are subjected to epoxy modification treatment by the interfacial compatibilizer, so that on one hand, the interfacial compatibilizer reacts with carboxyl groups at two ends of PBAT and PLA, and the compatibility of PBAT and PLA resin interfaces is improved; the mechanical property of the composite film can be greatly improved. On the other hand, the curcumin is a natural substance and has excellent oxidation resistance, and the compatibilizer modified by the curcumin acts on the PBAT / PLA phase interface, so that the oxidation resistance and the biodegradability of the composite film are effectively improved, and the service life of the composite film in a high-ultraviolet region is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of degradable films, and in particular to a PBAT / PLA antioxidant composite film and a preparation method thereof. Background Art

[0002] PBAT (polybutylene adipate-terephthalate) is undoubtedly one of the most commercially valuable bioplastics. It is a biodegradable plastic that can also be extracted from biomass. Currently, PBAT accounts for 19.2% of the bioplastics market, ranking alongside PLA (polylactic acid) as the most in-demand biopolymer. PBAT shares similar flexibility and resilience to PET, and its high elongation at break, good hydrophilicity, and processing properties make it an ideal industrial material. PBAT is widely used in the manufacture of packaging bags, mulch films, laminates, food packaging plastics, toothbrushes, and other products. Its flexibility can be enhanced by blending with other polymers. Researchers are working to create biodegradable polymers with optimal mechanical properties, biodegradability, and affordability.

[0003] PLA and PBAT are both currently commercially available biodegradable plastics. Using PLA and PBAT to prepare composite systems can simultaneously balance strength, modulus, toughness, and biodegradability, leveraging their strengths and overcoming their weaknesses. However, PLA / PBAT composites exhibit poor interfacial compatibility, leading to significant phase separation during processing and requiring bulking. To improve the compatibility of PLA / PBAT composites, the primary method currently employed is to add an interfacial compatibilizer to the PLA / PBAT composite.

[0004] Currently used interfacial compatibilizers are synthesized from petroleum-based materials, such as epoxy resins. These materials are limited in functionality, non-degradable, and offer suboptimal performance. Furthermore, additives are required to enhance the antioxidant properties of composite materials. Therefore, it is crucial for researchers to develop an interfacial compatibilizer that effectively compatibilizes PLA / PBAT composites and offers antioxidant properties. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a PBAT / PLA composite film with good compatibility and oxidation resistance.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] The first aspect of the present invention provides a PBAT / PLA antioxidant composite film, which comprises the following raw materials in terms of mass percentage:

[0008] PBAT resin 55-85%; PLA resin 5-25%; interface compatibilizer 0.1-3%; the rest is auxiliary agent; the structural formula of the interface compatibilizer is

[0009] Beneficial Effects: The PBAT / PLA antioxidant composite film of the present invention incorporates an interfacial compatibilizer. This interfacial compatibilizer, through epoxy modification of the phenolic hydroxyl groups at both ends of curcumin, reacts with the carboxyl groups at both ends of PBAT and PLA, enhancing the interfacial compatibility between PBAT and PLA resins and significantly improving the mechanical properties of the composite film. Furthermore, curcumin, a natural substance with excellent antioxidant properties, is applied to the PBAT / PLA interface by the modified curcumin compatibilizer, effectively improving the antioxidant and biodegradability of the composite film and extending its service life in areas with high UV rays.

[0010] Preferably, the following raw materials are included in percentage by mass: 60-80% PBAT resin; 7-20% PLA resin; 0.5-2% interfacial compatibilizer; and the remainder is auxiliary agent.

[0011] Preferably, the melt index of the PBAT resin is 2.0-4.5 g / 10 min, and the acid value of the PBAT resin is 1-1.9 mgKOH / g.

[0012] Preferably, the melt index of the PBAT resin is 3.0-3.5 g / 10 min, and the acid value of the PBAT resin is 1.1-1.4 mgKOH / g.

[0013] Preferably, the melt index of the PLA resin is 4.0-18.0 g / 10 min.

[0014] More preferably, the melt index of the PLA resin is 4.0-9.0 g / 10 min.

[0015] Preferably, the auxiliary agent includes talc and lubricating powder, and the weight percentage is: talc 1-10%; lubricating powder 0.2-1.2%.

[0016] More preferably, talc powder is 3-7%; slippery powder is 0.2-0.6%.

[0017] Preferably, the mesh size of the talc is 2000-9000 mesh.

[0018] More preferably, the mesh size of the talc is 2500-5000 mesh.

[0019] Preferably, the lubricant is one or more of stearamide, erucamide or oleamide.

[0020] More preferably, the lubricant is erucamide.

[0021] A second aspect of the present invention provides a method for preparing the above-mentioned PBAT / PLA antioxidant composite film, comprising the following steps:

[0022] S1 Preparation of interfacial compatibilizer:

[0023] Curcumin, epichlorohydrin and a solvent are mixed, and a catalyst is added to react to obtain an interfacial compatibilizer;

[0024] S2 Preparation of composite film

[0025] The PBAT resin, PLA resin, interfacial compatibilizer and additives are mixed evenly, added to an extruder, melt-extruded, cooled, and pelletized to obtain a modified material; the modified material is added to a film blowing machine to obtain a PBAT / PLA antioxidant composite film.

[0026] Preferably, the mass ratio of curcumin to epichlorohydrin is 40:66-101.

[0027] Preferably, the solvent is isopropyl alcohol and water.

[0028] Preferably, the catalyst is a base.

[0029] Preferably, the mixing time is 5-15 minutes.

[0030] Preferably, the temperature of the extruder is 140-220° C., and the rotation speed of the extruder is 150-600 rpm.

[0031] Preferably, the temperature of the film blowing machine is 140-200° C., and the rotation speed of the film blowing machine is 250-600 rpm. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Actual photos of the PBAT / PLA antioxidant composite films prepared in Examples 1-4 and Comparative Example 1;

[0033] Figure 2 This is the SEM image of the PBAT / PLA antioxidant composite film of Example 2;

[0034] Figure 3 It is the infrared spectrum of the PBAT / PLA antioxidant composite film of Example 2. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0037] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0038] Example 1

[0039] This embodiment provides a PBAT / PLA antioxidant composite film and a preparation method thereof, as follows:

[0040] S1 Preparation of interfacial compatibilizer:

[0041] Curcumin (20 g, 54.3 mmol), epichlorohydrin (33.5 g, 362 mmol), isopropyl alcohol (36 mL) and deionized water (15 mL) were added to a three-necked flask and placed in an oil bath at 95° C. for 30 min.

[0042] Subsequently, the liquid titration rate was controlled, and 15 mL of 4 mol / L NaOH solution was added dropwise within 20 minutes, and the reaction was continued for 1 hour. Then, 15 mL of 4 mol / L NaOH solution was added dropwise again. After the reaction was continued for 1 hour, the reaction mixture was cooled to room temperature to obtain a mixture, which was washed with 100 mL of water, 100 mL of ethanol-water mixture (ethanol to water volume ratio of 1:1) and 100 mL of ethanol in sequence. The washed solid was dried in an oven at 60° C. overnight to obtain an interfacial compatibilizer. The structural formula of the interfacial compatibilizer is:

[0043] S2 preparation of composite film:

[0044] PBAT resin (1000g, melt index of 3.2g / 10min, acid value of 1.3mgKOH / g), PLA resin (200g, melt index of 5.3g / 10min), interfacial compatibilizer (6.7g), talc (67g, 4000 mesh) and slip powder (6.7g) were placed in a high-speed mixer at a speed of 60rpm for 10min, and then added to a twin-screw extruder from the feed port. After melt extrusion, cooling and pelletizing, the speed of the twin-screw extruder was 155°C and 300rpm to obtain a modified material; the slip powder was erucamide.

[0045] The modified material was added into a film blowing machine at a temperature of 160° C. and a rotation speed of 300 rpm to produce a PBAT / PLA antioxidant composite film.

[0046] The compatibilization mechanism of the interfacial compatibilizer is as follows:

[0047]

[0048] The PBAT / PLA antioxidant composite film tested on a universal testing machine showed a stress of 15.38 MPa and a strain of 15.18%. The antioxidant properties of the PBAT / PLA antioxidant composite film were determined using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) method. The DPPH free radical scavenging rate of the PBAT / PLA antioxidant composite film of this example was 11.69%.

[0049] Example 2

[0050] This embodiment provides a PBAT / PLA antioxidant composite film and a preparation method thereof. Compared with Example 1, this embodiment differs in that the amount of the interfacial compatibilizer added is 13.5 g, and the other aspects are the same.

[0051] The PBAT / PLA antioxidant composite film tested on a universal testing machine showed a stress of 17.52 MPa and a strain of 12.23%. The antioxidant properties of the PBAT / PLA antioxidant composite film were determined using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) method. The DPPH free radical scavenging rate of the PBAT / PLA antioxidant composite film of this example was 15.38%.

[0052] The SEM spectrum of the PBAT / PLA antioxidant composite film is as follows Figure 2 As shown in the figure, it can be seen that the surface of the film is very smooth and there is no phase separation phenomenon, indicating that the interface compatibilizer has a good compatibilization effect. The infrared spectrum of the PBAT / PLA antioxidant composite film is shown in Figure 3 As shown, at 914cm -1The epoxy characteristic peak disappears, indicating that the interfacial compatibilizer is grafted onto the main chains of PBAT and PLA.

[0053] Example 3

[0054] This embodiment provides a PBAT / PLA antioxidant composite film and a preparation method thereof. Compared with Example 1, this embodiment differs in that the amount of the interfacial compatibilizer added is 20 g, and the other aspects are the same.

[0055] The PBAT / PLA antioxidant composite film tested on a universal testing machine showed a stress of 19.68 MPa and a strain of 10.16%. The antioxidant properties of the PBAT / PLA antioxidant composite film were determined using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) method. The DPPH free radical scavenging rate of the PBAT / PLA antioxidant composite film of this example was 21.10%.

[0056] Example 4

[0057] This embodiment provides a PBAT / PLA antioxidant composite film and a preparation method thereof. Compared with Example 1, this embodiment differs in that the amount of the interfacial compatibilizer added is 27 g, and the other contents are the same.

[0058] The PBAT / PLA antioxidant composite film tested on a universal testing machine showed a stress of 23.9 MPa and a strain of 8.14%. The antioxidant properties of the PBAT / PLA antioxidant composite film were determined using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) method. The DPPH free radical scavenging rate of the PBAT / PLA antioxidant composite film of this example was 31.09%.

[0059] according to Figure 1 It can be seen that the PBAT / PLA antioxidant composite film is yellow, and the color of the film gradually deepens as the amount of interfacial compatibilizer added increases.

[0060] Comparative Example 1

[0061] This comparative example provides a PBAT / PLA composite film. Compared with Example 1, this comparative example differs in that no interfacial compatibilizer is added, and all other aspects are the same.

[0062] The PBAT / PLA composite film, tested on a universal testing machine, showed a stress of 9.56 MPa and a strain of 12.32%. The antioxidant properties of the PBAT / PLA composite film were determined using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) method, which revealed a DPPH free radical scavenging rate of 2.62%.

[0063] according to Figure 1As shown, the PBAT / PLA composite film of this comparative example is white because no interfacial compatibilizer is added. Compared with Example 1, the addition of an interfacial compatibilizer to the PBAT / PLA composite film in this comparative example improves the mechanical properties of the PBAT / PLA antioxidant composite film, effectively improves its antioxidant properties, and extends the service life of the PBAT / PLA composite film.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A PBAT / PLA antioxidant composite film, characterized in that: The following raw materials are included in percentage by mass: PBAT resin 55-85%; PLA resin 5-25%; interface compatibilizer 0.1-3%; the rest is auxiliary agent; the structural formula of the interface compatibilizer is 2. The PBAT / PLA antioxidant composite film according to claim 1, characterized in that: The raw materials include the following according to mass percentage: 60-80% of PBAT resin; 7-20% of PLA resin; 0.5-2% of interface compatibilizer; and the rest are auxiliary agents.

3. The PBAT / PLA antioxidant composite film according to claim 1 or 2, characterized in that: The melt index of the PBAT resin is 2.0-4.5 g / 10 min, and the acid value of the PBAT resin is 1-1.9 mgKOH / g.

4. The PBAT / PLA antioxidant composite film according to claim 3, characterized in that: The melt index of the PBAT resin is 3.0-3.5 g / 10 min, and the acid value of the PBAT resin is 1.1-1.4 mgKOH / g.

5. The PBAT / PLA antioxidant composite film according to claim 1 or 2, characterized in that: The melt index of the PLA resin is 4.0-18.0 g / 10 min.

6. The PBAT / PLA antioxidant composite film according to claim 1, characterized in that: The auxiliary agent comprises talcum powder and lubricating powder, and the weight percentage is as follows: talcum powder 1-10%; lubricating powder 0.2-1.2%.

7. The PBAT / PLA antioxidant composite film according to claim 6, characterized in that: The mesh size of the talcum powder is 2000-9000 mesh.

8. The PBAT / PLA antioxidant composite film according to claim 6, characterized in that: The lubricant is one or more of stearamide, erucamide or oleamide.

9. The method for preparing the PBAT / PLA antioxidant composite film according to any one of claims 1 to 8, wherein: The following steps are involved: S1 Preparation of interfacial compatibilizer: Curcumin, epichlorohydrin and a solvent are mixed, and a catalyst is added to react to obtain an interfacial compatibilizer; S2 preparation of composite film: The PBAT resin, PLA resin, interfacial compatibilizer and additives are mixed evenly, added to the extruder, melt-extruded, cooled, and pelletized to obtain a modified material; The modified material was added into a film blowing machine to obtain a PBAT / PLA antioxidant composite film.

10. The method for preparing the PBAT / PLA antioxidant composite film according to claim 9, characterized in that: The mass ratio of curcumin to epichlorohydrin is 40:66-101; the mixing time is 5-15 minutes; the temperature of the extruder is 140-220° C.; and the temperature of the film blowing machine is 140-200° C.

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