Preparation method and application method of high-barrier PBAT / PHA film

Abstract

The invention belongs to the field of high polymer materials, and discloses a preparation method and an application method of a high-barrier PBAT / PHA film, and the preparation method comprises the following steps: adding a plasticizer and PHA powder into a high-speed mixer for high-speed stirring, and then adding an isocyanate chain extender and a heat stabilizer for uniform mixing. The preparation method comprises the following steps: carrying out melt extrusion by using a twin-screw extruder, carrying out air-cooling granulation to obtain modified PHA particles for later use, and carrying out high-speed stirring and premixing on an inorganic filler and a coupling agent for later use. According to the present invention, the low molecular weight PHA is subjected to chain extension treatment by using the chain extender so as to increase the mobility of the polymer molecular chain and reduce the melting temperature of the polymer, and the low molecular weight PHA is subjected to chain extension treatment by using the chain extender, such that the number of the low molecular weight PHA is reduced, the overall molecular weight of the PHA is improved, and the heat resistance processing performance of the PHA is improved.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and specifically relates to a preparation method and an application method of a high-barrier PBAT / PHA film. Background Art

[0002] PBAT is one of the most popular biodegradable materials in recent years and also one of the biodegradable materials with the largest scale. Due to the presence of soft aliphatic chains and rigid aromatic groups in its molecular structure, it has unique properties such as high elongation and high ductility. At the same time, PBAT has excellent processing performance, so PBAT has become the best choice to replace traditional plastic (PE) films. PHA is a general term for polyhydroxyalkanoates. More than 150 kinds of PHA have been discovered so far. There are huge differences in the structural properties of different kinds of PHA. For example, P3HB (poly-3-hydroxybutyrate) and P4HB (poly-4-hydroxybutyrate) both belong to PHA, but P3HB is a highly crystalline polymer with characteristics such as a high melting point (170 - 175°C) and high strength; while P4HB is an amorphous polymer with characteristics such as a low melting point (50 - 60°C), high elasticity, high elongation, and soft texture. Therefore, the processing technologies of different kinds of PHA are very different. Currently, the mainly mass-produced PHA are PHB, PHBV, P34HB, and PHBHHX. Among them, PHB is a homopolymer without soft segments in its molecular structure, resulting in low ductility, so it is difficult to be applied to film bags. PHBV, P34HB, and PHBHHX belong to copolymers with soft segments and certain ductility, making their application in film bags possible. The poor barrier property of PBAT limits its application in fresh-keeping film bags. PHA is one of the few high-barrier materials among biodegradable materials, but due to the close proximity of its melting point and decomposition temperature, and its wide molecular weight distribution and a large number of oligomers, the processing of PHA is relatively difficult. At the same time, since PHA is obtained by spray drying after biological fermentation, its form is powder. The mixing of powder and particles will lead to uneven mixing due to density differences, affecting the performance of the composite material.

[0003] In the Chinese patent with the publication number "CN116333459A", a high-barrier PBAT material, its preparation method and application are disclosed. It mentions using PHA to improve the barrier property of PBAT to prepare a high-barrier PBAT film, but it fails to clarify which specific product or products of PHA are used. However, the onset decomposition temperature of PHA is 180°C, and the melting point of PGA is 225°C. There is a risk that PGA starts to melt while PHA has decomposed during production and processing. Therefore, its production difficulty poses a severe test to the existing processing technology.

[0004] In the Chinese patent with the publication number "CN106957514B", a PBAT-based biodegradable composite material with high water vapor barrier properties is disclosed. PHA and inorganic fillers are used to improve the barrier properties of PBAT. The interfacial interaction between inorganic fillers and resin is enhanced by blending PBAT and inorganic fillers with the assistance of a compatibilizer. In the patent, PHA is not clearly specified as which product, and at the same time, it does not mention how to solve the processing problems of PHA.

[0005] In order to solve the problems of poor barrier properties of PBAT, difficult processing of PHA, and uneven blending of PHA powder and PBAT particles, a preparation method and application method of a high-barrier PBAT / PHA film are thus proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application method of a high-barrier PBAT / PHA film to solve the problems raised in the above background technology.

[0007] To achieve the above purpose, the present invention provides the following technical solutions: A preparation method and application method of a high-barrier PBAT / PHA film, characterized in that it includes the following steps:

[0008] S1: Add P34HB powder and a plasticizer to a high-speed mixer for high-speed stirring, then add a chain extender and a heat stabilizer to the high-speed mixer, continue stirring for 2 min, and melt-extrude the blended raw materials through a twin-screw extruder, and obtain modified PHA particles through air-cooled pelletizing.

[0009] S2: Add a titanate coupling agent and inorganic fillers to a high-speed mixer for high-speed stirring to obtain treated inorganic fillers.

[0010] S3: Add PBAT, modified PHA particles, inorganic fillers, and other additives to a high-speed mixer for blending, then melt-extrude the blended materials through a twin-screw extruder, obtain a PBAT / PHA composite material through air-cooled pelletizing, and finally process it into a high-barrier PBAT / PHA film through a blown film machine.

[0011] Preferably, the plasticizer is a mixture of glycerol, ESO, and sorbitol, and the ratio of glycerol:ESO:sorbitol is 2:1:2. The stirring frequency of the high-speed mixer is 30 HZ, and the stirring time is 3 min. The extrusion temperature of the twin-screw extruder is 120 - 145 °C. The chain extender is diphenylmethane diisocyanate, and the heat stabilizer is a mixture of calcium-zinc stabilizer and methyl mercaptan organotin stabilizer, and the ratio of calcium-zinc stabilizer:methyl mercaptan organotin stabilizer is 1:1. The other additives include a compatibilizer, a coupling agent, and an antiblocking agent.

[0012] Preferably, in the step S2, the inorganic filler includes one or more of calcium carbonate, talcum powder, inorganic clay, mica, and montmorillonite. The stirring frequency of the high-speed mixer is 35HZ, and the stirring time is 5 minutes.

[0013] Preferably, in the step S3, the stirring frequency of the high-speed mixer is 30HZ, the stirring time is 1 minute, and the extrusion temperature of the twin-screw extruder is 140-165°C.

[0014] Preferably, the PBAT is one or more of one-step PBAT or two-step PBAT, and the melt index of the PBAT is 3-5 g / 10min.

[0015] Preferably, the compatibilizer is one or more of maleic anhydride grafted product, glycidyl methacrylate grafted product, and ethylene-acrylate-maleic anhydride terpolymer.

[0016] Preferably, the coupling agent is one or more of silane coupling agent and titanate coupling agent.

[0017] Preferably, the antiblocking agent is one or more of nano-silica, oleic acid amide, and erucic acid amide. The particle size of the erucic acid amide is 200 mesh.

[0018] Preferably, the content of maleic anhydride in the ethylene-acrylate-maleic anhydride terpolymer is 0.5%.

[0019] Application of the high-barrier PBAT / PHA film prepared by the above preparation method in fresh-keeping bags

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention uses a plasticizer to improve the processing performance of PHA during the extrusion process. The plasticizer molecules are inserted between the polymer molecular chains, weakening the intermolecular forces between the polymer molecular chains, thereby increasing the mobility of the polymer molecular chains, reducing the melting temperature of the polymer. At the same time, a chain extender is used to perform chain extension treatment on low-molecular-weight PHA, reducing the number of low-molecular-weight PHA and increasing the overall molecular weight of PHA, thereby improving the heat-resistant processing performance of PHA.

[0022] (2) The chain extender used in the present invention is an isocyanate-based chain extender, rather than an epoxy-functional group-based chain extender. The reaction temperature of the isocyanate-based chain extender is low, which can better fit the processing temperature of PHA.

[0023] (3) The present invention uses the process of modifying PHA to prepare modified PHA particles from PHA powder, avoiding the disadvantage of uneven mixing of PHA powder and PBAT particles.

[0024] (4) The present invention pre-treats the inorganic filler. The pre-treatment method is to mix the coupling agent and the inorganic filler at high speed. There is an isopropoxy group in the titanate coupling agent, which is a hydrolyzable group that can couple with inorganic substances. It can tightly connect the inorganic filler and the organic polymer material, giving full play to the role of each titanate molecule, increasing the compatibility between the inorganic filler and the resin, reducing the interfacial free energy, making the interface between the resin and the inorganic filler more tightly combined, thereby improving the barrier property of the PBAT / PHA composite material. Description of the Drawings

[0025] Figure 1 is a flow chart of the present invention. Detailed Embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] Please refer to Figure 1 as shown, the present invention provides the following technical solutions:

[0028] The following is the preparation of the modified PHA in the embodiment

[0029] Example 1

[0030] Weigh and mix the plasticizer in the ratio of glycerol: ESO: sorbitol = 2:1:2, and weigh and mix the heat stabilizer in the ratio of calcium-zinc stabilizer: methyl mercaptan organotin stabilizer = 1:1. Add 70 parts of P34HB powder and 30 parts of plasticizer to a high-speed mixer for high-speed stirring. The frequency of the mixer is 30HZ, and the stirring time is 3min. Then add 0.4 parts of chain extender (diphenylmethane diisocyanate) and 0.8 parts of heat stabilizer to the high-speed mixer and continue stirring for 2min; extrude the blended raw materials through a twin-screw extruder. The temperature range of the extruder is 120 - 145°C, and after air-cooling and pelletizing, the modified PHA (labeled as G1) is obtained.

[0031] Example 2

[0032] This example has the same steps as Example 1, except for the components. The components of this example are: 75 parts of P34HB, 25 parts of plasticizer, 0.5 parts of chain extender, and 0.9 parts of heat stabilizer, to obtain the modified PHA (labeled as G2).

[0033] Example 3

[0034] This example has the same steps as Example 1, except for the different components. The components of this example are as follows: 80 parts of P34HB, 20 parts of plasticizer, 0.6 parts of chain extender, and 1 part of heat stabilizer, obtaining modified PHA (labeled as G3).

[0035] Table 1 Formulation of Components for Preparation of Modified PHA in Examples 1 - 3

[0036]

[0037] The following examples are for the preparation of high - barrier PBAT / PHA films:

[0038] The following examples all adopt the following preparation steps:

[0039] Add titanate coupling agent and inorganic filler (talc powder) to a high - speed mixer for high - speed stirring. The mixer frequency is 35 HZ and the stirring time is 5 min. Obtain the treated inorganic filler (talc powder).

[0040] Add PBAT, modified PHA particles, inorganic filler (talc powder), and other additives to a high - speed mixer for blending. The mixer frequency is 30 HZ and the stirring time is 1 min. Then extrude the blended material through a twin - screw extruder for melt extrusion. The extrusion temperature range is 140 - 165 °C. Obtain PBAT / PHA composite materials through air - cooling pelletizing, and finally process them into high - barrier PBAT / PHA films through a blown - film machine.

[0041] Example 4

[0042] Prepare high - barrier PBAT / PHA films with 60 parts of PBAT, 15 parts of modified PHA (G1), 20 parts of talc powder, 0.3 part of coupling agent, 0.8 part of compatibilizer, and 0.4 part of erucamide according to the above steps.

[0043] Example 5

[0044] Prepare high - barrier PBAT / PHA films with 55 parts of PBAT, 20 parts of modified PHA (G1), 25 parts of talc powder, 0.4 part of coupling agent, 0.9 part of compatibilizer, and 0.5 part of erucamide according to the above steps.

[0045] Example 6

[0046] Prepare high - barrier PBAT / PHA films with 45 parts of PBAT, 25 parts of modified PHA (G1), 30 parts of talc powder, 0.5 part of coupling agent, 1 part of compatibilizer, and 0.6 part of erucamide according to the above steps.

[0047] Example 7

[0048] Prepare a high-barrier PBAT / PHA film by mixing 60 parts of PBAT, 15 parts of modified PHA (G2), 20 parts of talcum powder, 0.3 part of coupling agent, 0.8 part of compatibilizer, and 0.4 part of erucamide according to the above steps.

[0049] Example 8

[0050] Prepare a high-barrier PBAT / PHA film by mixing 55 parts of PBAT, 20 parts of modified PHA (G2), 25 parts of talcum powder, 0.4 part of coupling agent, 0.9 part of compatibilizer, and 0.5 part of erucamide according to the above steps.

[0051] Example 9

[0052] Prepare a high-barrier PBAT / PHA film by mixing 45 parts of PBAT, 25 parts of modified PHA (G2), 30 parts of talcum powder, 0.5 part of coupling agent, 1 part of compatibilizer, and 0.6 part of erucamide according to the above steps.

[0053] Example 10

[0054] Prepare a high-barrier PBAT / PHA film by mixing 60 parts of PBAT, 15 parts of modified PHA (G3), 20 parts of talcum powder, 0.3 part of coupling agent, 0.8 part of compatibilizer, and 0.4 part of erucamide according to the above steps.

[0055] Example 11

[0056] Prepare a high-barrier PBAT / PHA film by mixing 55 parts of PBAT, 20 parts of modified PHA (G3), 25 parts of talcum powder, 0.4 part of coupling agent, 0.9 part of compatibilizer, and 0.5 part of erucamide according to the above steps.

[0057] Example 12

[0058] Prepare a high-barrier PBAT / PHA film by mixing 45 parts of PBAT, 25 parts of modified PHA (G3), 30 parts of talcum powder, 0.5 part of coupling agent, 1 part of compatibilizer, and 0.6 part of erucamide according to the above steps.

[0059] Table 2 Formulations of High-Barrier PBAT / PHA Films in Examples 4 - 12

[0060]

[0061] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples. Any other changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

[0062] To assist personnel in understanding the present invention, the following comparative examples are provided. The following are the comparative examples:

[0063] The preparation of the modified PHA for the comparative examples is as follows:

[0064] Comparative Example 1

[0065] Weigh and mix the plasticizers in an equal ratio according to the ratio of glycerol:ESO:sorbitol of 2:1:2, and weigh and mix the heat stabilizers in an equal ratio according to the ratio of calcium-zinc stabilizer:methyl mercaptan organotin stabilizer of 1:1 for later use.

[0066] Add 55 parts of P34HB powder and 45 parts of plasticizer to a high-speed mixer and stir at a high speed. The frequency of the mixer is 30HZ and the stirring time is 3min. Then add 0.1 part of chain extender (diphenylmethane diisocyanate) and 0.3 part of heat stabilizer to the high-speed mixer and continue stirring for 2min; extrude the blended raw materials through a twin-screw extruder. The temperature range of the extruder is 120-145°C, and after air-cooling and pelletizing, the modified PHA (marked as D1) is obtained.

[0067] Comparative Example 2

[0068] This comparative example has the same preparation steps as Comparative Example 1, except that the components of this comparative example are: 95 parts of P34HB, 5 parts of plasticizer, 1 part of chain extender, and 2 parts of heat stabilizer. The modified PHA (marked as D2) is obtained.

[0069] Comparative Example 3

[0070] The raw material components of the modified PHA in this comparative example are the same as those of the modified PHA in Example 3, that is: 80 parts of P34HB, 20 parts of plasticizer, 0.6 part of chain extender, and 1 part of heat stabilizer. The difference is that this comparative example does not go through the extrusion modification step, and directly weighs and mixes in an equal ratio for later use. The mixed PHA (marked as D3) is obtained.

[0071] Comparative Example 4

[0072] This comparative example uses PHB as the raw material, and the component ratio is the same as that of the modified PHA (G1) in Example 1, that is, 70 parts of PHB, 30 parts of plasticizer, 0.4 part of chain extender, and 0.8 part of heat stabilizer. This comparative example has the same preparation steps as Comparative Example 1. Since the melting point of PHB is high and it cannot be processed at 120-145°C, the processing temperature of the extruder is different for this comparative example, and the processing temperature is 175-180°C. The modified PHA (D4) is obtained.

[0073] Table 3 Preparation Formulas of the Modified PHA in Comparative Examples 1-5

[0074]

[0075]

[0076] The preparation of the PBAT / PHA film for the comparative example is as follows:

[0077] Comparative Example 5

[0078] PBAT, modified PHA (D1), inorganic filler (talc powder), and other additives were added to a high-speed mixer for blending. The mixer frequency was 30 HZ, and the mixing time was 1 min. Then, the blended material was melt-extruded through a twin-screw extruder. The extrusion temperature range was 140 - 165 °C. After air-cooling and pelletizing, a PBAT / PHA composite material was obtained. Finally, the PBAT / PHA film was processed by blowing using a blown film machine.

[0079] 65 parts of PBAT, 15 parts of modified PHA (D1), 20 parts of talc powder, 0.3 part of coupling agent, 0.8 part of compatibilizer, and 0.4 part of erucamide were used to prepare the PBAT / PHA film according to the above steps.

[0080] The difference between this Comparative Example 1 and Example 4 is that the raw material components for the preparation of the modified PHA (D1) are not within the range of the raw material components for the preparation of the modified PHA specified in the present invention. And the talc powder was not treated.

[0081] In this comparative example, there was too much plasticizer in the modified PHA (D1), and too little chain extender. A large amount of low-molecular-weight PHA still existed, resulting in a decrease in the melt strength of PBAT / PHA, poor blown film forming effect, and phenomena such as plasticizer precipitation. It affected the barrier property of the film.

[0082] Comparative Example 6

[0083] 55 parts of PBAT, 20 parts of modified PHA (D2), 25 parts of talc powder, 0.4 part of coupling agent, 0.9 part of compatibilizer, and 0.5 part of erucamide were used to prepare the PBAT / PHA film according to the steps of Comparative Example 5.

[0084] The difference between this comparative example and Example 8 is that the raw material components for the preparation of the modified PHA (D2) are not within the range of the raw material components for the preparation of the modified PHA specified in the present invention. And the talc powder was not treated.

[0085] There was very little plasticizer in the modified PHA (D2) in this comparative example, and too much chain extender, resulting in a crosslinking phenomenon, which caused phenomena such as crystal points in the subsequent film and affected the forming of the film.

[0086] Comparative Example 7

[0087] 45 parts of PBAT, 25 parts of modified PHA (D3), 30 parts of talc powder, 0.5 part of coupling agent, 1 part of compatibilizer, and 0.6 part of erucamide were used to prepare the PBAT / PHA film according to the steps of Comparative Example 5.

[0088] The difference between this comparative example and Example 12 is that the mixed PHA (D3) was not extruded, modified and pelletized. And the talcum powder was not treated. All the materials were blended together to prepare the PBAT / PHA film.

[0089] Comparative Example 8

[0090] 55 parts of PBAT, 20 parts of modified PHA (D4), 25 parts of talcum powder, 0.4 part of coupling agent, 0.9 part of compatibilizer, 0.5 part of erucamide. The difference between this comparative example and Example 5 is that the raw material for preparing the modified PHA (D4) is PHB, and the talcum powder was not treated.

[0091] Prepare the PBAT / PHA film according to the steps of Comparative Example 5. Due to the high melting point of PHB, the extrusion processing temperature is 175 - 180 °C. The film blowing temperature is 170 - 175 °C. Since the melting points of PBAT and PHB differ greatly, a higher temperature is required to melt PHB for film blowing. The increase in temperature causes a serious decrease in the melt strength of PBAT, and the film blowing processability of PHB is too poor to form a film by blowing.

[0092] Table 4 Formulations of PBAT / PHA Films for Comparative Examples 5 - 8

[0093]

[0094]

[0095] Comparative Example 9

[0096] Prepare the PBAT / PHA film by mixing 30 parts of PBAT, 60 parts of modified PHA (G1), 10 parts of talcum powder, 0.1 part of coupling agent, 0.4 part of compatibilizer, and 0.1 part of erucamide according to the steps of Comparative Example 4.

[0097] The difference between this comparative example and the examples is that the proportions of the components of the PBAT / PHA composite material are not within the scope defined in the present invention.

[0098] In this comparative example, due to the too high content of the modified PHA, the melt strength of the PBAT / PHA composite material decreases severely, and the film bubble is extremely unstable during film blowing, making it impossible to blow the film normally.

[0099] Comparative Example 10

[0100] Prepare the PBAT / PHA film by mixing 80 parts of PBAT, 9 parts of modified PHA (G2), 10 parts of talcum powder, 0.8 part of coupling agent, 2 parts of compatibilizer, and 1 part of erucamide according to the steps of Comparative Example 4.

[0101] The difference between this comparative example and the examples lies in that the component ratios of the PBAT / PHA composite material are not within the scope specified in the present invention.

[0102] Comparative Example 11

[0103] 100 parts of PBAT were directly processed by a blown film machine to form a PBAT film.

[0104] Table 5 Formulations of PBAT / PHA Films for Comparative Examples 9 - 11

[0105]

[0106] The following are the test results of the examples and comparative examples. Examples 1 - 3 and Comparative Examples 1 - 5 are the preparatory processes for the preparation of PBAT / PHA films, so they are not tested and judged. Only the final film products are tested.

[0107] Table 6 Performance Test Results of Examples 4 - 12 and Comparative Examples 5 - 11

[0108]

[0109]

[0110] In Examples 4 - 12, the water vapor transmission rate coefficient of PBAT was reduced by 47 - 67% and the oxygen transmission rate coefficient was reduced by 40.7 - 74.8% by using the technical means of the present invention. Compared with the pure PBAT film of Comparative Example 11, the barrier property of the PBAT / PHA film of the present invention is significantly better.

[0111] In Comparative Examples 5 - 7, since the component ratios of the modified PHA (D1) in Comparative Example 5 and the modified PHA (D1) in Comparative Example 6 are not within the scope of the component ratios of the modified PHA raw materials specified in the present invention, and the modified PHA (D3) in Comparative Example 7 has not undergone extrusion modification. PHA failed to effectively improve the processing performance and still contained a large amount of low - molecular - weight PHA, resulting in poor molding effect. Moreover, the filler was not pretreated, resulting in an insufficiently tight contact interface between the inorganic filler and the resin, and water vapor and oxygen gas molecules were more likely to permeate. Therefore, there is no significant improvement in the barrier property of PBAT.

[0112] In Comparative Example 8, PHB was used for modification. Since the melting points of PHB and PBAT differ too much, in order to melt PHB, the blown film temperature needs to be increased. However, the increase in the blown film temperature led to a significant decrease in the melt strength of PBAT, resulting in the inability to form a blown film.

[0113] The PBAT / PHA raw material components in Comparative Example 9 are not within the scope specified in the present invention. The content of the modified PHA is too high and the content of PBAT is too low. PBAT cannot form a continuous phase, resulting in the inability to exhibit the processing performance of high melt strength of PBAT during processing, which affects the blown film processing of PBAT / PHA, so blown film forming cannot be achieved.

[0114] The PBAT / PHA raw material components in Comparative Example 10 are not within the scope specified in the present invention. The content of the modified PHA is too low, and the high barrier property of PHA cannot be effectively exhibited in the composite material, so the improvement of the barrier effect is poor.

[0115] PHA, as a general term for polyhydroxyalkanoates, currently has more than 150 discovered structures. In the present invention, P34HB, PHBV, and PHBHHX with soft segments are selected from the existing mass-produced PHA structures to increase the barrier property of PBAT. Different from other existing patents, PHA is not generally regarded as a single material, and the high-crystalline and high-melting-point (170 - 175 °C) PHA such as PHB is not used to modify the barrier property of PBAT. Because PHB needs to be melted at 170 - 175 °C, and the blown film temperature of PBAT is 150 - 160 °C, high-melting-point raw materials are extremely likely to generate crystal points during the blown film process, and with the increase of the blown film temperature, the melt strength of PBAT will decrease, affecting the blown film forming performance of the PBAT / PHA composite material.

[0116] The melting temperature of PHA is close to the starting decomposition temperature, and the molecular weight distribution of PHA is relatively wide (PDI is about 2 - 4), with more low-molecular-weight PHA. Low-molecular-weight PHA is extremely likely to decompose during processing, so the starting decomposition temperature of PHA is close to the melting temperature.

[0117] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high barrier PBAT / PHA film, characterized in that: The steps include: S1: P34HB powder and plasticizer are added to a high-speed mixer for high-speed stirring, and then the chain extender and heat stabilizer are added to the high-speed mixer, and stirring is continued for 2 minutes. The blended raw materials are melt-extruded through a twin-screw extruder, and pelletized after air cooling to obtain modified PHA particles; S2: adding the titanate coupling agent and the inorganic filler into a high-speed mixer for high-speed stirring to obtain a treated inorganic filler; S3: PBAT, modified PHA particles, inorganic fillers and other additives are added to a high-speed mixer for blending, and then the blended materials are melt-extruded through a twin-screw extruder, and the PBAT / PHA composite material is obtained through air cooling and pelletizing, and finally processed into a high-barrier PBAT / PHA film through a film blowing machine.

2. The method for preparing a high barrier PBAT / PHA film according to claim 1, characterized in that: The plasticizer is a mixture of glycerol, ESO and sorbitol, and the ratio of glycerol:ESO:sorbitol is 2:1:

2. The stirring frequency of the high-speed mixer is 30HZ, the stirring time is 3min, the extrusion temperature of the twin-screw extruder is 120-145°C, the chain extender is diphenylmethane diisocyanate, the heat stabilizer is a mixture of a calcium zinc stabilizer and a methyl mercaptan organotin stabilizer, and the ratio of the calcium zinc stabilizer to the methyl mercaptan organotin stabilizer is 1:

1. The other additives include a compatibilizer, a coupling agent and an opening agent.

3. The method for preparing a high barrier PBAT / PHA film according to claim 1, characterized in that: In S2, the inorganic filler includes one or more of calcium carbonate, talc, inorganic clay, mica, and montmorillonite, and the stirring frequency of the high-speed mixer is 35 Hz, and the stirring time is 5 min.

4. The method for preparing a high barrier PBAT / PHA film according to claim 1, characterized in that: In S3, the stirring frequency of the high-speed mixer is 30 Hz, the stirring time is 1 min, and the extrusion temperature of the twin-screw extruder is 140-165°C.

5. The method for preparing a high barrier PBAT / PHA film according to claim 1, characterized in that: The PBAT is one or more of one-step PBAT and two-step PBAT, and the melt index of the PBAT is 3-5 g / 10 min.

6. The method for preparing a high barrier PBAT / PHA film according to claim 2, characterized in that: The compatibilizer is one or more of maleic anhydride grafts, glycidyl methacrylate grafts, and ethylene-acrylate-maleic anhydride terpolymers.

7. The method for preparing a high barrier PBAT / PHA film according to claim 1, characterized in that: The coupling agent is one or more of a silane coupling agent and a titanate coupling agent.

8. The method for preparing a high barrier PBAT / PHA film according to claim 2, characterized in that: The opening agent is one or more of nano silicon dioxide, oleamide, and erucamide, and the particle size of the erucamide is 200 meshes.

9. The method for preparing a high barrier PBAT / PHA film according to claim 6, characterized in that: The maleic anhydride content in the ethylene-acrylate-maleic anhydride terpolymer is 0.5%.

10. Application of the high barrier PBAT / PHA film prepared by the method for preparing the high barrier PBAT / PHA film according to any one of claims 1 to 9 in plastic wrap bags.

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