Environment-friendly degradable plastic food packaging bag and preparation method thereof

Abstract

The invention discloses an environment-friendly degradable plastic food packaging bag and a preparation method thereof.The food packaging bag is prepared from, by weight, 90-100 parts of PBAT, 10-20 parts of PLA, 15-20 parts of antibacterial modified nano calcium carbonate, 1-2 parts of polyethylene wax and 1-2 parts of titanium dioxide, a large proportion of PBAT and a small proportion of PLA are used as base materials, and the base materials are prepared into the environment-friendly degradable plastic food packaging bag. When the component ratio difference is large, the intermolecular acting force of PBAT and PLA is stronger, the miscibility is better, the two base materials are mixed and dissolved to prepare base particles, and then the base particles are mixed and melted with other components, so that better compatibility can be achieved, and the mechanical property of the prepared degradable plastic food packaging bag is more excellent; when the antibacterial modified nano calcium carbonate is melted with other components of the plastic food packaging bag, the antibacterial modified nano calcium carbonate has better compatibility and better material fluidity during melting, meanwhile, silver of the prepared plastic bag is not easy to separate out, and the antibacterial performance of the plastic food packaging bag can be kept for a long time.

Description

Technical Field

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

[0002] The practicality and portability of plastic products have brought great convenience to people's lives. With the increasing use of plastic products, serious environmental pollution problems have been brought to the environment. Producing and using degradable materials can reduce the dependence on fossil fuels such as petroleum, which is conducive to promoting the process of sustainable development and reducing environmental pollution.

[0003] PBAT is one of the most widely used matrix materials for preparing degradable plastics. It is a polymer material copolymerized from butylene adipate and butylene terephthalate. Its chain segment structure contains rigid aromatic groups and flexible aliphatic chains, endowing it with good ductility and thermal stability. In addition, PBAT has good degradability and can be decomposed into harmless substances in the natural environment. PLA is a natural polymer material mainly derived from plant starch and is often used as a matrix material for preparing degradable plastics. It has excellent biodegradability and can be recycled biologically, making it an environmentally friendly degradable material. The plastic bags made of PLA are soft in texture, high in transparency, and have good plasticity and processing performance, so they are widely used in the production of degradable plastics. Due to its excellent strength and modulus, PLA is also an ideal choice for reinforcing PBAT. By combining the advantages of these two degradable plastics, PBAT and PLA, the blended material can overcome their respective disadvantages and thus achieve more ideal performance. PBAT and PLA have good chemical structural complementarity. The material formed after blending has both the good ductility and thermal stability of PBAT and the excellent strength and modulus of PLA. The PLA / PBAT blend can inherit the high strength of PLA and the high elasticity of PBAT and can still be degraded. At the same time, this PLA / PBAT blend is still a degradable material, avoiding environmental pollution and waste of resources.

[0004] Plastic food packaging bags are involved in all aspects of our lives. With the improvement of living quality and people's attention to health, higher requirements are put forward for these daily-use plastic packaging bags in close contact. They should be non-toxic and antibacterial. Elemental silver has broad-spectrum and high-efficiency bactericidal ability and is a very good antibacterial agent. Nano-silver is often added to antibacterial plastics to increase antibacterial performance. However, inorganic nano-silver has poor dispersibility and is easy to precipitate, and cannot maintain antibacterial performance persistently.

[0005] Calcium carbonate, as the most commonly used inorganic filler in plastic processing for filling and modification, blending with PBAT can not only reduce the production cost of products but also improve the processing performance of PBAT. However, calcium carbonate is prone to agglomeration, so it is difficult to be evenly dispersed in polymers and has very poor compatibility with PBAT. Therefore, it is necessary to modify calcium carbonate to solve its compatibility problem. Summary of the Invention

[0006] The purpose of the present invention is to provide an environmentally friendly degradable plastic food packaging bag and its preparation method.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] The environmentally friendly degradable plastic food packaging bag comprises the following raw materials in parts by weight: 90 - 100 parts of PBAT, 10 - 20 parts of PLA, 15 - 20 parts of antibacterial modified nano calcium carbonate, 1 - 2 parts of polyethylene wax, and 1 - 2 parts of titanium dioxide.

[0009] Furthermore, the preparation method of the antibacterial modified nano calcium carbonate is as follows:

[0010] S1, Weigh 11 - mercaptoundecanoic acid and add it to a reaction flask, add 80 - 100 ml of absolute ethanol, place the reaction flask in a constant temperature water bath with magnetic stirring, and stir at a water bath temperature of 45 - 55 °C for 20 - 30 min to obtain a modified solution;

[0011] S2, Weigh nano calcium carbonate and add it to the reaction flask, then add 400 - 500 ml of an ethanol aqueous solution with a mass fraction of 20 - 30%, place the reaction flask in a heating jacket with magnetic stirring, heat while stirring to a temperature of 65 - 70 °C, then slowly add the prepared modified solution, add it all within 20 - 30 min, then keep the temperature at 65 - 70 °C and continue stirring for 2 - 4 h. After the reaction is completed, cool to room temperature, filter, and wash the filter cake with absolute ethanol;

[0012] S3, Then immerse the filter cake in a silver antibacterial solution, place it in a constant temperature water bath with magnetic stirring, stir at a water bath temperature of 45 - 55 °C for 2 - 3 h, take it out, filter, wash it with purified water, then place the filter cake in an oven, dry it at 100 - 105 °C for 10 - 16 h, and grind it to obtain modified nano calcium carbonate.

[0013] Furthermore, the mass of the 11 - mercaptoundecanoic acid is 0.7 - 1.0 g.

[0014] Furthermore, the particle size of the nano calcium carbonate is 1 - 100 nm.

[0015] Furthermore, the mass of the nano calcium carbonate is 15 - 20 g.

[0016] Furthermore, the preparation of the silver antibacterial solution is as follows:

[0017] Weigh 8 - 10 mg of silver nitrate, 45 - 50 mg of sodium citrate and 200 ml of deionized water and add them to a beaker. After complete dissolution, add 3 - 5 ml of an aqueous sodium borohydride solution with a mass fraction of 0.03 - 0.05%. Then, add an aqueous sodium hydroxide solution with a concentration of 10 - 20 mol / L dropwise to adjust the pH of the solution to 10.0 - 13.0. Stir and mix evenly, age for 2 - 3 h, and finally obtain the silver antibacterial agent after centrifugation, washing with water and drying. Dissolve it with deionized water to prepare a silver antibacterial solution with a mass concentration of 0.5% - 0.8%.

[0018] Furthermore, the volume of the silver antibacterial solution is 400 - 500 ml.

[0019] A preparation method of an environment-friendly degradable plastic food packaging bag includes the following steps:

[0020] In the first step, put the formulated amounts of PBAT and PLA into an oven, vacuum dry at 50 - 55 °C for 8 - 10 h, then add them to a twin-screw extruder for melt mixing, extrude and granulate to obtain plastic base pellets for standby;

[0021] In the second step, add the plastic base pellets prepared in the first step, the component amounts of antibacterial modified nano calcium carbonate, polyethylene wax, and titanium dioxide to a high-speed mixer and mix at room temperature for 3 - 5 min; In the third step, add the mixed material of the second step to a twin-screw extrusion unit for mixed extrusion, then cut the extruded long strip sample into pellets, and then add them to a blow molding machine for extrusion molding to obtain the environment-friendly degradable plastic food packaging bag.

[0022] Advantages of the present invention:

[0023] The present invention provides an environment-friendly degradable plastic food packaging bag, which has good biodegradability and persistent antibacterial properties. Using PBAT with a large proportion and PLA with a small proportion as the base materials, when the component ratios are quite different, the intermolecular force between PBAT and PLA is stronger and the melt miscibility is better. The two base materials are first miscible to prepare base pellets, and when mixed with other components, they will have better compatibility, and the mechanical properties of the obtained degradable plastic food packaging bag are more excellent;

[0024] As a filler, nano-calcium carbonate has a large number of hydroxyl groups on its surface. It is modified with 11-mercaptoundecanoic acid. The carboxyl group on 11-mercaptoundecanoic acid can react with the hydroxyl groups on the surface of nano-calcium carbonate. The modified nano-calcium carbonate is impregnated in a silver antibacterial solution. The mercapto group with adsorption properties can adsorb silver atoms and coordinate with them, and then fix them on calcium carbonate. When the antibacterial modified nano-calcium carbonate is melted with other components of the plastic food packaging bag, it has better compatibility, and the fluidity of the material during melting is better. At the same time, the silver in the made plastic bag is not easy to precipitate, and the antibacterial performance of the plastic food packaging bag can be maintained persistently.

[0025] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 Are the infrared spectra of 11-mercaptoundecanoic acid, antibacterial modified nano-calcium carbonate, and nano-calcium carbonate;

[0028] Figure 2 Are the calcium element distribution maps of Comparative Example 1 (Figure a) and Example 3 (Figure b) by EDS energy spectrum analysis. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] In the following embodiments

[0031] The preparation method of the antibacterial modified nano-calcium carbonate is as follows:

[0032] Preparation of the modification solution: Weigh 0.8 g of 11-mercaptoundecanoic acid and add it to a reaction flask, add 100 ml of absolute ethanol, place the reaction flask in a constant temperature water bath with magnetic stirring, and stir for 30 min at a water bath temperature of 50 °C to obtain the modification solution;

[0033] Preparation of antibacterial modified nano calcium carbonate: Weigh 20 g of nano calcium carbonate (particle size 1 - 100 nm;) and add it to a reaction flask. Then add 500 ml of ethanol aqueous solution with a mass fraction of 30%. Place the reaction flask in a heating jacket with magnetic stirring, heat and stir to 70 °C. Then slowly add the prepared modification solution, and finish adding it within 30 min. Then keep the temperature at 70 °C and continue stirring for 4 h. After the reaction is completed, cool to room temperature, filter, wash the filter cake with absolute ethanol. Then immerse the filter cake in 500 ml of silver antibacterial solution, place it in a constant temperature water bath with magnetic stirring, stir at a water bath temperature of 50 °C for 2 h, take it out, filter, wash with purified water, then put the filter cake into an oven, dry at 105 °C for 15 h, and grind to obtain modified nano calcium carbonate;

[0034] As Figure 1 shown, in the infrared spectrum of the modified nano calcium carbonate, the stretching vibration peaks of methylene in 11 - mercaptoundecanoic acid are at 2933 cm -1 , 2860 cm -1 , and the stretching vibration peak of ester group is at 1759 cm -1 , indicating that 11 - mercaptoundecanoic acid has formed a bond on the nano calcium carbonate.

[0035] The preparation method of the antibacterial modifier described above is:

[0036] Weigh 10 mg of silver nitrate, 50 mg of sodium citrate and 200 ml of de - purified water and add them to a beaker. After complete dissolution, add 3 ml of sodium borohydride aqueous solution with a mass fraction of 0.05%. Then dropwise add sodium hydroxide aqueous solution with a concentration of 15 mol / L to adjust the pH of the solution to 10.0 - 13.0, stir and mix evenly, age for 3 h. Finally, obtain silver antibacterial agent after centrifugation, washing with water and drying, dissolve it with deionized water, and prepare a silver antibacterial solution with a mass concentration of 0.8%.

[0037] Example 1

[0038] The present invention is an environment - friendly degradable plastic food packaging bag, which comprises the following raw materials in parts by weight: 100 parts of PBAT, 15 parts of PLA, 20 parts of antibacterial modified nano calcium carbonate, 1 part of polyethylene wax, and 1 part of titanium dioxide;

[0039] The melt flow index of the PBAT described above is 5.6 g / 10 min (190 °C / 2.16 kg), and the density is 1.26 g / cm 3 ;

[0040] The melt flow index of the PLA described above is 6.2 g / 10 min (190 °C / 2.16 kg), and the density is 1.24 g / cm 3 ;

[0041] The method for preparing an environmentally friendly degradable plastic food packaging bag comprises the following steps:

[0042] In the first step, the formulated amount of PBAT and PLA is placed in an oven, vacuum dried at 55°C for 8 hours, and then added to a twin-screw extruder for melt mixing, extrusion granulation, and plastic base particles are obtained for standby use;

[0043] In the second step, the plastic base particles prepared in the first step and the component amounts of antibacterial modified nano calcium carbonate, polyethylene wax, and titanium dioxide are added into a high-speed mixer and mixed at room temperature for 5 minutes;

[0044] The third step is to add the mixed material from the second step into a twin-screw extruder unit for mixed extrusion, and then cut the extruded long strip sample into pellets, and then add it into a blow molding machine for extrusion molding to obtain an environmentally friendly and degradable plastic food packaging bag.

[0045] Example 2

[0046] The present invention is an environmentally friendly degradable plastic food packaging bag, comprising the following raw materials in parts by weight: 90 parts of PBAT, 20 parts of PLA, 16 parts of antibacterial modified nano calcium carbonate, 1.5 parts of polyethylene wax, and 1.5 parts of titanium dioxide;

[0047] The PBAT melt flow index is 5.6 g / 10 min (190 ° C / 2.16 kg) and the density is 1.26 g / cm 3 ;

[0048] The PLA melt flow index is 6.2g / 10min (190℃ / 2.16kg) and the density is 1.24g / cm 3 ;

[0049] The method for preparing an environmentally friendly degradable plastic food packaging bag comprises the following steps:

[0050] In the first step, the formulated amount of PBAT and PLA is placed in an oven and vacuum dried at 55°C for 10 hours, then added to a twin-screw extruder for melt mixing, extrusion granulation, and plastic base particles are obtained for standby use;

[0051] In the second step, the plastic base particles prepared in the first step and the component amounts of antibacterial modified nano calcium carbonate, polyethylene wax, and titanium dioxide are added into a high-speed mixer and mixed at room temperature for 3 minutes;

[0052] The third step is to add the mixed material from the second step into a twin-screw extruder unit for mixed extrusion, and then cut the extruded long strip sample into pellets, and then add it into a blow molding machine for extrusion molding to obtain an environmentally friendly and degradable plastic food packaging bag.

[0053] Example 3

[0054] The present invention relates to an environmentally friendly degradable plastic food packaging bag, which comprises the following raw materials in parts by weight: 95 parts of PBAT, 10 parts of PLA, 18 parts of antibacterial modified nano calcium carbonate, 2 parts of polyethylene wax, and 2 parts of titanium dioxide;

[0055] The melt flow index of the PBAT is 5.6 g / 10 min (190 °C / 2.16 kg), and the density is 1.26 g / cm 3 ;

[0056] The melt flow index of the PLA is 6.2 g / 10 min (190 °C / 2.16 kg), and the density is 1.24 g / cm 3 ;

[0057] A preparation method of the environmentally friendly degradable plastic food packaging bag comprises the following steps:

[0058] In the first step, the formulated amounts of PBAT and PLA are placed in an oven and vacuum dried at 50 °C for 10 h, and then added to a twin-screw extruder for melt mixing and extrusion granulation to obtain plastic pellets for standby;

[0059] In the second step, the plastic pellets prepared in the first step and the component amounts of antibacterial modified nano calcium carbonate, polyethylene wax, and titanium dioxide are added to a high-speed mixer and mixed at room temperature for 4 min;

[0060] In the third step, the mixed material in the second step is added to a twin-screw extruder unit for mixing and extrusion, and then the extruded long strip sample is cut into pellets, and then added to a blow molding machine for extrusion molding to obtain the environmentally friendly degradable plastic food packaging bag.

[0061] Comparative Example 1

[0062] The present invention relates to an environmentally friendly degradable plastic food packaging bag, which comprises the following raw materials in parts by weight: 95 parts of PBAT, 10 parts of PLA, 18 parts of nano calcium carbonate, 2 parts of nano silver oxide, 2 parts of polyethylene wax, and 2 parts of titanium dioxide;

[0063] The melt flow index of the PBAT is 5.6 g / 10 min (190 °C / 2.16 kg), and the density is 1.26 g / cm 3 ;

[0064] The melt flow index of the PLA is 6.2 g / 10 min (190 °C / 2.16 kg), and the density is 1.24 g / cm 3 ;

[0065] A preparation method of the environmentally friendly degradable plastic food packaging bag comprises the following steps:

[0066] First step: Put the formula amount of PBAT and PLA into an oven, vacuum dry at 50 °C for 10 h, then add them to a twin-screw extruder for melt mixing, extrude and pelletize to obtain plastic base pellets for standby;

[0067] Second step: Add the plastic base pellets prepared in the first step, and the component amounts of nano calcium carbonate, nano silver oxide, polyethylene wax, and titanium dioxide to a high-speed mixer, and mix at room temperature for 4 min;

[0068] Third step: Add the mixed material of the second step to a twin-screw extrusion unit for mixing and extrusion, then cut the extruded long strip sample into pellets, and then add them to a blow molding machine for extrusion molding to obtain an environmentally friendly degradable plastic food packaging bag.

[0069] As Figure 2 shown, the EDS energy spectrum analysis calcium element distribution maps of Comparative Example 1 (Figure a) and Example 3 (Figure b) show that the modified nano calcium carbonate is more uniformly distributed in the degradable plastic system (Example 3).

[0070] Comparative Example 2

[0071] The present invention is an environmentally friendly degradable plastic food packaging bag, comprising the following raw materials in parts by weight: 95 parts of PBAT, 10 parts of PLA, 18 parts of antibacterial modified nano calcium carbonate, 2 parts of polyethylene wax, and 2 parts of titanium dioxide;

[0072] The melt flow index of the PBAT is 5.6 g / 10 min (190 °C / 2.16 kg), and the density is 1.26 g / cm 3 ;

[0073] The melt flow index of the PLA is 6.2 g / 10 min (190 °C / 2.16 kg), and the density is 1.24 g / cm 3 ;

[0074] A preparation method of an environmentally friendly degradable plastic food packaging bag, comprising the following steps:

[0075] Second step: Add the component amounts of each raw material to a high-speed mixer, and mix at room temperature for 4 min;

[0076] Third step: Add the mixed material of the second step to a twin-screw extrusion unit for mixing and extrusion, then cut the extruded long strip sample into pellets, and then add them to a blow molding machine for extrusion molding to obtain an environmentally friendly degradable plastic food packaging bag.

[0077] The mechanical properties of the degradable plastic food packaging bags of Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 1:

[0078] Tensile property test: It was carried out using a WDW type universal tensile testing machine, and the tensile test was carried out in accordance with the national standard GB / T 1040.1-2018.

[0079] Determination of impact strength: An XJJD-5J type electronic impact testing machine was used, and the test was carried out in accordance with the national standard GB / T1843-2008.

[0080] Table 1

[0081] Tensile strength (Mpa) Elongation at break (%) <![CDATA[Impact strength (KJ / m 3 )]]> Example 1 44.8 659.4 48.5 Example 2 46.3 692.7 51.2 Example 3 45.7 668.3 49.3 Comparative Example 1 25.4 253.6 21.5 Comparative Example 2 39.6 571.1 41.6

[0082] As can be seen from Table 1, the degradable plastic food packaging bags prepared in this application have good mechanical properties. In Comparative Example 1, there is no modified nano-calcium carbonate, and the mechanical properties of the prepared packaging bags are poor. In Comparative Example 2, each component is directly mixed and melted, and the compatibility may be slightly poor. The performance of the prepared food packaging bags is slightly weaker than that of Example 3 in terms of mechanical properties.

[0083] Degradation property test

[0084] The natural burial method was adopted. The samples of Examples 1-3 and Comparative Examples 1-2 were buried in the test field, the burial depth was about 15 cm, shaded, and after 3 months of burial, the samples were taken out and the degradation degree was visually observed. The results are shown in Table 2:

[0085] Table 2

[0086]

[0087] Antibacterial property test: The test standard is QB / T 2591-2003A "Test Methods for Antibacterial Properties and Antibacterial Effects of Antibacterial Plastics", and the results are shown in Table 3:

[0088]

[0089] As can be seen from Table 3, the degradable plastic food packaging bags prepared in this application have good and lasting antibacterial properties and stable performance.

[0090] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of this technology make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all belong to the protection scope of the present invention.

Claims

1. Environmentally friendly degradable plastic food packaging bag, characterized by: The invention comprises the following raw materials in parts by weight: 90-100 parts of PBAT, 10-20 parts of PLA, 15-20 parts of antibacterial modified nano calcium carbonate, 1-2 parts of polyethylene wax and 1-2 parts of titanium dioxide.

2. The environmentally friendly degradable plastic food packaging bag according to claim 1, characterized in that: The preparation method of the antibacterial modified nano calcium carbonate is: S1, weigh 11-mercaptoundecanoic acid and add it to a reaction bottle, add 80-100 ml of anhydrous ethanol, place the reaction bottle in a constant temperature water bath with magnetic stirring, and stir for 20-30 minutes at a water bath temperature of 45-55° C. to obtain a modified solution; S2, weigh nano calcium carbonate and add it to the reaction bottle, then add 400-500 ml of 20-30% ethanol aqueous solution, place the reaction bottle in a heating jacket with magnetic stirring, heat to 65-70°C while stirring, then slowly add the prepared modified solution, add it within 20-30 minutes, then keep the temperature at 65-70°C and continue stirring for 2-4 hours. After the reaction is completed, cool to room temperature, filter, and wash the filter cake with anhydrous ethanol; S3, then immerse the filter cake in silver antibacterial solution, put it in a constant temperature water bath with magnetic stirring, stir it at a water bath temperature of 45-55°C for 2-3h, take it out, filter it, wash it with purified water, then put the filter cake into an oven, dry it at 100-105°C for 10-16h, and obtain modified nano calcium carbonate after grinding.

3. The environmentally friendly degradable plastic food packaging bag according to claim 2, characterized in that: The mass of the 11-mercaptoundecanoic acid is 0.7-1.0 g.

4. The environmentally friendly degradable plastic food packaging bag according to claim 2, characterized in that: The particle size of the nano calcium carbonate is 1-100nm.

5. The environmentally friendly degradable plastic food packaging bag according to claim 2, characterized in that: The mass of the nano calcium carbonate is 15-20g.

6. The environmentally friendly degradable plastic food packaging bag according to claim 2, characterized in that: The preparation of the silver antibacterial liquid is as follows: 8-10 mg of silver nitrate, 45-50 mg of sodium citrate and 200 ml of purified water are weighed and added into a beaker. After the silver nitrate, 3-5 ml of a sodium borohydride aqueous solution with a mass fraction of 0.03-0.05% is added. Then, a sodium hydroxide aqueous solution with a concentration of 10-20 mol / L is added dropwise to adjust the pH value of the solution to 10.0-13.

0. The mixture is stirred and mixed uniformly, aged for 2-3 hours, and finally, the silver antibacterial agent is obtained after centrifugation, washing with water and drying. The silver antibacterial agent is dissolved in deionized water to prepare a silver antibacterial solution with a mass concentration of 0.5%-0.8%.

7. The environmentally friendly degradable plastic food packaging bag according to claim 2, characterized in that: The volume of the silver antibacterial liquid is 400-500ml.

8. A method for preparing an environmentally friendly degradable plastic food packaging bag as claimed in claim 1, characterized in that: The following steps are involved: The first step is to put the formulated amount of PBAT and PLA into an oven, vacuum dry them at 50-55°C for 8-10 hours, then add them into a twin-screw extruder for melt mixing, extrusion granulation, and obtain plastic base particles for standby use; In the second step, the plastic base particles prepared in the first step and the antibacterial modified nano calcium carbonate, polyethylene wax and titanium dioxide are added into a high-speed mixer and mixed at room temperature for 3-5 minutes; The third step is to add the mixed material from the second step into a twin-screw extruder unit for mixed extrusion, and then cut the extruded long strip sample into pellets, and then add it into a blow molding machine for extrusion molding to obtain an environmentally friendly and degradable plastic food packaging bag.

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