An environmentally friendly and degradable packaging film and its preparation method

Abstract

The present invention provides an environmentally friendly degradable packaging film and a preparation method thereof, which are prepared from the following raw materials in parts by weight: 70-85 parts of polybutylene adipate / terephthalate, 7-11 parts of modified polylactic acid, 12-18 parts of starch, and 0.5-2 parts of antioxidant; the modified polylactic acid is prepared from the following raw materials in parts by weight: 82-88 parts of polylactic acid, 12-15 parts of nano-oxide, and 2-4 parts of coupling agent. By scientifically compounding polybutylene adipate / terephthalate, modified polylactic acid, starch and antioxidant, the present invention can enable each raw material to play an assisting and synergistic role, achieve good heat-sealing stability, have good mechanical properties, be degradable, environmentally friendly and green.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging films, and particularly relates to an environmentally friendly degradable packaging film and a preparation method thereof. Background Art

[0002] At present, most of the raw materials used in food packaging films on the market are still polyethylene, polyvinyl chloride, polypropylene, etc. These packaging films bring a lot of convenience to people's lives. However, these films have stable properties and are difficult to degrade, causing great pollution to the environment. Developing environmentally friendly degradable packaging films has become a major trend in the film industry. With the change of people's lifestyle, for the sake of convenience, people are increasingly keen on using paper bowls to hold delicious food. PLA-coated paper bowls can meet the requirements of degradability. However, when taking out food in a paper bowl, in order to prevent leakage of soup, water, etc., a paper lid needs to be used to cover the PLA-coated paper bowl. The method of covering with a paper lid will have problems such as not being tightly covered and leakage. Therefore, it is necessary to find an environmentally friendly degradable packaging film that can be heat-sealed with PLA-coated paper bowls to solve the above problems. At present, degradable packaging film materials are prepared from relatively easily degradable raw materials such as cellulose and starch. However, such packaging film materials still have poor mechanical properties such as tensile strength and elongation at break, poor heat sealing, resulting in the phenomenon of not being tightly covered, and also have poor antibacterial properties, making it difficult to be used on a large scale. Summary of the Invention

[0003] In view of this, the present invention provides an environmentally friendly degradable packaging film and a preparation method thereof.

[0004] The technical solution of the present invention is realized as follows:

[0005] An environmentally friendly degradable packaging film is prepared from the following raw materials in parts by weight: 70 - 85 parts of polybutylene adipate / terephthalate, 7 - 11 parts of modified polylactic acid, 12 - 18 parts of starch, and 0.5 - 2 parts of antioxidant; the modified polylactic acid is prepared from the following raw materials in parts by weight: 82 - 88 parts of polylactic acid, 12 - 15 parts of nano-oxide, and 2 - 4 parts of coupling agent.

[0006] Further, the antioxidant includes at least one of antioxidant 1010 and antioxidant 1076.

[0007] Further, the nano-oxide includes titanium dioxide and zinc oxide with a mass ratio of (2 - 3):1, the particle size of nano-titanium dioxide is 80 - 100 nm, and the particle size of nano-zinc oxide is 80 - 100 nm.

[0008] Further, the coupling agent is one or a combination of two of 3-aminopropyltriethoxysilane and 3-aminopropylmethyldimethoxysilane.

[0009] Further, the preparation method of the modified polylactic acid is as follows: Add polylactic acid to N,N-dimethylacetamide and stir to dissolve it for the first time. Then add nano-oxide and coupling agent and stir and react for the second time. Remove bubbles by ultrasonic treatment, then carry out vacuum drying and pulverize to obtain the modified polylactic acid.

[0010] Further, the mass ratio of polylactic acid to N,N-dimethylacetamide is 1:(2-3).

[0011] Further, the temperature of the first stirring is 70-80°C and the rotation speed is 200-300 r / min; the temperature of the second stirring is 70-80°C, the rotation speed is 500-600 r / min, and the reaction time is 20-25 min.

[0012] Further, the temperature for ultrasonic defoaming is 70-80°C, the ultrasonic vibration frequency is 15-20 KHz, and the time is 25-30 min.

[0013] A preparation method of an environmentally friendly degradable packaging film includes the following steps: Mix polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant evenly to obtain a mixed material. Granulate the mixed material by extrusion to obtain particles. Then blow the particles into a film through a single-screw extruder. Compose, cure, and slit the film to obtain the environmentally friendly degradable packaging film.

[0014] Further, the extrusion temperature during the film blowing process is 140-150°C, the screw rotation speed is 40-50 r / min, and the film thickness is 0.03-0.05 mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] By scientifically compounding polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant, the present invention can make each raw material play a synergistic effect, achieve good heat-sealing stability, have good mechanical properties, be degradable, environmentally friendly, and green.

[0017] By modifying the degradable material polylactic acid with specific modified raw materials and processes, the present application can effectively improve the problem of great brittleness of polylactic acid during the processing process, can also improve its mechanical properties, and can also improve the compatibility and stability of polylactic acid with polybutylene adipate / terephthalate and starch, improve the heat-sealing adhesiveness between the packaging film prepared in the present application and the PLA coated paper bowl, and can also greatly enhance the toughness of the prepared packaging film material, which is beneficial to its wide application. In addition, after modifying polylactic acid, the antibacterial property of the prepared packaging film can be improved, and it has good antibacterial effects on Escherichia coli and Staphylococcus aureus, and can avoid food spoilage.

[0018] This application can improve the reaction efficiency of polylactic acid with nano-oxides and coupling agents through primary stirring, secondary stirring, and ultrasonic defoaming processes, enhance the mutual compounding of polylactic acid and nano-oxides, thereby effectively improving brittleness, enhancing its stability, improving its mechanical properties, and also enhancing its antibacterial properties. Detailed Embodiments

[0019] To better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0020] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0021] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial channels.

[0022] Example 1 - Preparation of Environmentally Friendly Degradable Packaging Film

[0023] The environmentally friendly degradable packaging film is prepared from the following raw materials by weight: 68 parts of polybutylene adipate / terephthalate, 11 parts of modified polylactic acid, 20 parts of starch, and 1 part of antioxidant; the antioxidant is antioxidant 1010; the modified polylactic acid is prepared from the following raw materials by weight: 88 parts of polylactic acid, 9 parts of nano-oxide, and 3 parts of coupling agent; the nano-oxide includes titanium dioxide with a particle size of 80 nm and zinc oxide with a particle size of 80 nm in a mass ratio of 2.5:1; the coupling agent is composed of 3-aminopropyltriethoxysilane and 3-aminopropylmethyldimethoxysilane in a mass ratio of 3:1;

[0024] The preparation method of the modified polylactic acid is as follows: Take polylactic acid and N,N-dimethylacetamide in a mass ratio of 1:3, add polylactic acid to N,N-dimethylacetamide and stir to dissolve at 70°C and a rotation speed of 300 r / min for the first time, then add nano-oxide and coupling agent and stir and react at 70°C and a rotation speed of 500 r / min for 25 min, perform ultrasonic defoaming for 30 min at a temperature of 70°C and an ultrasonic vibration frequency of 20 KHz, and then perform vacuum drying and pulverization to obtain modified polylactic acid;

[0025] The preparation method of the environmentally friendly degradable packaging film includes the following steps: Mix polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant evenly to obtain a mixed material, extrude and granulate the mixed material to obtain particulate matter, and then blow the particulate matter into a film through a single-screw extruder. The extrusion temperature during the film blowing process is 140°C, the screw rotation speed is 40 r / min, the film thickness is 0.03 mm, and the film is compounded, cured, and slit to obtain the environmentally friendly degradable packaging film.

[0026] Example 2 - Preparation of Environmentally Friendly Degradable Packaging Film

[0027] The environmentally friendly degradable packaging film is prepared from the following raw materials in parts by weight: 80.5 parts of polybutylene adipate / terephthalate, 7 parts of modified polylactic acid, 12 parts of starch, and 0.5 part of antioxidant; the antioxidant is antioxidant 1076; the modified polylactic acid is prepared from the following raw materials in parts by weight: 85 parts of polylactic acid, 12 parts of nano-oxide, and 3 parts of coupling agent; the nano-oxide includes titanium dioxide with a particle size of 100 nm and zinc oxide with a particle size of 90 nm in a mass ratio of 2:1; the coupling agent is 3-aminopropyltriethoxysilane;

[0028] The preparation method of the modified polylactic acid is as follows: Take polylactic acid and N,N-dimethylacetamide in a mass ratio of 1:2.5, add polylactic acid to N,N-dimethylacetamide and stir and dissolve it once at 80°C and a rotation speed of 250 r / min, then add nano-oxide and coupling agent and stir and react for 22 min at 80°C and a rotation speed of 550 r / min, carry out ultrasonic defoaming for 25 min at a temperature of 80°C and an ultrasonic vibration frequency of 18 KHz, then carry out vacuum drying and pulverize to obtain modified polylactic acid;

[0029] The preparation method of the environmentally friendly degradable packaging film includes the following steps: Mix polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant evenly to obtain a mixed material, extrude and granulate the mixed material to obtain particulate matter, then blow the particulate matter into a film through a single-screw extruder. The extrusion temperature during the film blowing process is 150°C, the screw rotation speed is 50 r / min, the film thickness is 0.04 mm, and the film is compounded, cured, and slit to obtain the environmentally friendly degradable packaging film.

[0030] Example 3 - Preparation of Environmentally Friendly Degradable Packaging Film

[0031] The environmentally friendly degradable packaging film is prepared from the following raw materials in parts by weight: 76 parts of polybutylene adipate / terephthalate, 8 parts of modified polylactic acid, 15 parts of starch, and 1 part of antioxidant; the antioxidant is composed of antioxidant 1010 and antioxidant 1076 in a mass ratio of 1:1; the modified polylactic acid is prepared from the following raw materials in parts by weight: 84 parts of polylactic acid, 14 parts of nano-oxide, and 2 parts of coupling agent; the nano-oxide includes titanium dioxide with a particle size of 90 nm and zinc oxide with a particle size of 100 nm in a mass ratio of 3:1; the coupling agent is 3-aminopropylmethyldimethoxysilane;

[0032] The preparation method of the modified polylactic acid is as follows: Take polylactic acid and N,N-dimethylacetamide with a mass ratio of 1:2. Add the polylactic acid to N,N-dimethylacetamide and stir to dissolve it once at 75°C and a rotation speed of 200 r / min. Then add nano-oxide and coupling agent and stir and react for 20 min at 75°C and a rotation speed of 600 r / min. Carry out ultrasonic defoaming for 30 min under the conditions of a temperature of 75°C and an ultrasonic vibration frequency of 15 KHz. Then carry out vacuum drying and pulverize to obtain the modified polylactic acid;

[0033] The preparation method of the environmentally friendly degradable packaging film includes the following steps: Mix polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant evenly to obtain a mixed material. Granulate the mixed material by extrusion to obtain particulate matter. Then blow the particulate matter into a film through a single-screw extruder. The extrusion temperature during the film blowing process is 140°C, the screw rotation speed is 50 r / min, the film thickness is 0.05 mm. Carry out compounding, aging, and slitting of the film to obtain the environmentally friendly degradable packaging film.

[0034] Comparative Example 1

[0035] The difference between this comparative example and Example 3 is that: change the raw material ratio of the environmentally friendly degradable packaging film, and the rest is the same as in Example 3.

[0036] The environmentally friendly degradable packaging film of this comparative example is prepared from the following raw materials in parts by weight: 68 parts of polybutylene adipate / terephthalate, 5 parts of modified polylactic acid, 26 parts of starch, and 1 part of antioxidant.

[0037] Comparative Example 2

[0038] The difference between this comparative example and Example 3 is that: replace the modified polylactic acid with pure polylactic acid, and the rest is the same as in Example 3.

[0039] Comparative Example 3

[0040] The difference between this comparative example and Example 3 is that: change the preparation method of polylactic acid, and the rest is the same as in Example 3.

[0041] The preparation method of the modified polylactic acid in this comparative example is as follows: Take polylactic acid and N,N-dimethylacetamide with a mass ratio of 1:2. Mix polylactic acid, N,N-dimethylacetamide, nano-oxide, and coupling agent evenly and carry out stirring reaction for 50 min under the condition of 400 r / min. Then carry out vacuum drying and pulverize to obtain the modified polylactic acid.

[0042] Perform performance tests on the blown film materials prepared in the above Examples 1-3 and Comparative Examples 1-3, and measure the tensile strength, elongation at break, water vapor transmission rate, and antibacterial performance of the blown film materials.

[0043] (1) Determination of Tensile Strength, Elongation at Break, and Water Vapor Transmission Rate

[0044] The determination of tensile strength and elongation at break refers to GB / T 1040.3 - 2006 "Plastics - Determination of Tensile Properties - Part 3: Test Conditions for Films and Sheets". The water vapor transmission rate refers to GB - T 26253 - 2010 "Determination of Water Vapor Transmission Rate of Plastic Films and Sheets". The water vapor transmission performance of the blown - film materials prepared in Examples 1 - 3 and Comparative Examples 1 - 3 was tested using a film moisture permeability tester. The test results are shown in Table 1 below.

[0045] Table 1 Test Results of Tensile Strength / Elongation at Break and Water Vapor Transmission Rate of Blown - Film Materials

[0046]

[0047] The above results show that the blown - film materials prepared in Examples 1 - 3 of the present invention have good tensile strength and elongation at break, and can reduce the water vapor transmission performance. Compared with Example 3, in Comparative Example 1, due to the change in the dosage of the raw material formula, the components did not play a synergistic effect, resulting in a decrease in the tensile strength and elongation at break of the film material. Compared with Example 3, in Comparative Example 2, the polylactic acid was not modified, and in Comparative Example 3, the modification method of polylactic acid was changed, resulting in the failure of the nanomaterials to form a dense composite material with polylactic acid, the effect of improving the brittleness of polylactic acid was not obvious, and the mechanical property modification effect decreased, thus affecting the tensile strength, elongation at break, and water vapor transmission performance of the film - forming material.

[0048] (2) Antibacterial Performance

[0049] Using Staphylococcus aureus (ATCC 6538), Escherichia coli (8099), and Candida albicans (ATCC10231) as the strains respectively, the antibacterial performance of the packaging films prepared in Examples 1 - 3 and Comparative Examples 1 - 3 was tested by the shaking flask method. The test results are shown in Table 2 below.

[0050] Table 2 Antibacterial Performance of Blown - Film Materials

[0051]

[0052]

[0053] The above results show that the antibacterial properties of the packaging films prepared in Examples 1 - 3 of the present invention are better than those of Comparative Examples 1 - 3. Using a reasonable raw material ratio can enable each component to play a synergistic effect and achieve an effective antibacterial effect. And through reasonable process modification of polylactic acid, it can play a good antibacterial role in the packaging film.

[0054] In addition, the packaging film materials prepared in Examples 1-3 and Comparative Examples 1-3 were heat-sealed with PLA-coated paper bowls. The PLA-coated paper bowls had a capacity specification of 500 ml and were filled with a mixture of peanut oil and water with a total volume of 450 mL, where the volume ratio of peanut oil to water was 2:3. The corresponding heat-sealing experimental parameters were as follows: temperature 220°C, time 1 s; heat-sealing pressure 4 KG. The heat-sealing effect was tested as shown in Table 3 below.

[0055] Table 3 Heat-sealing test of packaging film

[0056] Visual observation of heat-sealing Example 1 Good seal, no cracking or leakage Example 2 Good seal, no cracking or leakage Example 3 Good seal, no cracking or leakage Comparative Example 1 Slightly poor seal, with slight leakage Comparative Example 2 Poor seal, with cracking and leakage Comparative Example 3 Poor seal, with cracking and leakage

[0057] The above results show that the preparation methods and raw material ratios of Examples 1-3 of the present invention can enable the prepared packaging film materials to achieve good heat-sealing stability with PLA-coated paper bowls, avoiding leakage. Compared with Example 3, in Comparative Example 1, the dosage ratio of packaging film raw materials was changed; in Comparative Example 2, polylactic acid was not modified; in Comparative Example 3, the modification method of polylactic acid was changed, resulting in a weakened synergistic effect between raw materials and a decline in the effect.

[0058] Finally, the environmentally friendly degradable packaging films prepared in Examples 1-3 of the present invention were cut into fragments of 5 cm × 5 cm, and then buried in natural soil at a depth of 10 cm (the soil had a pH value of 7.78, an organic matter content of 46.02 g / kg, an alkaline hydrolyzable nitrogen content of 24.8 mg / 100 g, and an available phosphorus content of 30.96 g / kg). After 5 months of soil burial, they were dug out and observed to have completely degraded, indicating that the packaging films prepared by the present invention have good degradation performance.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An environmentally friendly and degradable packaging film, characterized in that, Prepared from the following raw materials in parts by weight: 70 - 85 parts of polybutylene adipate / terephthalate, 7 - 11 parts of modified polylactic acid, 12 - 18 parts of starch, 0.5 - 2 parts of antioxidant; the modified polylactic acid is prepared from the following raw materials in parts by weight: 82 - 88 parts of polylactic acid, 12 - 15 parts of nano - oxide, 2 - 4 parts of coupling agent; The nano - oxide includes titanium dioxide and zinc oxide with a mass ratio of (2 - 3):1, the particle size of nano - titanium dioxide is 80 - 100 nm, and the particle size of nano - zinc oxide is 80 - 100 nm; The preparation method of the modified polylactic acid is as follows: Add polylactic acid into N,N - dimethylacetamide for the first - stage stirring and dissolution, then add nano - oxide and coupling agent for the second - stage stirring reaction, ultrasonic defoaming, and then vacuum drying and pulverizing to obtain the modified polylactic acid; the temperature of the first - stage stirring is 70 - 80 °C, and the rotation speed is 200 - 300 r / min; the temperature of the second - stage stirring is 70 - 80 °C, the rotation speed is 500 - 600 r / min, and the reaction time is 20 - 25 min.

2. The environmentally friendly and degradable packaging film according to claim 1, characterized in that, The antioxidant includes at least one of antioxidant 1010 and antioxidant 1076.

3. The environmentally friendly and degradable packaging film according to claim 1, wherein The coupling agent is one or a combination of two of 3 - aminopropyltriethoxysilane and 3 - aminopropylmethyldimethoxysilane.

4. The environmentally friendly and degradable packaging film according to claim 1, characterized in that, The mass ratio of polylactic acid to N,N - dimethylacetamide is 1:(2 - 3).

5. The environmentally friendly and degradable packaging film according to claim 1, wherein The temperature of ultrasonic defoaming is 70 - 80 °C, the ultrasonic vibration frequency is 15 - 20 KHz, and the time is 25 - 30 min.

6. The preparation method of the environmentally friendly degradable packaging film according to any one of claims 1-5, characterized in that, Including the following steps: Mix polybutylene adipate / terephthalate, modified polylactic acid, starch, and antioxidant evenly to obtain a mixed material, extrude - granulate the mixed material to obtain particles, then blow - mold the particles into a film through a single - screw extruder, compound the film, age it, and slit it to obtain an environmentally friendly degradable packaging film.

7. The preparation method of the environmentally friendly degradable packaging film according to claim 6, characterized in that, The extrusion temperature during the blow - molding process is 140 - 150 °C, the screw rotation speed is 40 - 50 r / min, and the film thickness is 0.03 - 0.05 mm.

Images