Natural degradable PE packaging bag and preparation process thereof

Abstract

The invention belongs to the technical field of packaging bags, and provides a PE packaging bag capable of being naturally degraded and a preparation technology of the PE packaging bag capable of being naturally degraded. The degradable plastic is prepared from the following raw materials in parts by weight: 40-60 parts of modified polyethylene resin, 20-30 parts of polylactic acid, 15-25 parts of a starch-based degradable material, 5-10 parts of nano cellulose, 5-10 parts of a biodegradable plasticizer, 0.5-1.5 parts of an antioxidant, 0.2-0.8 part of a photoinitiator, 1-3 parts of an enzymatic degradation additive and 2-5 parts of microorganism-containing carrier particles, according to the invention, various modes of degradable group introduction, enzymatic degradation and microbial degradation are creatively fused, an all-around, synergistic and efficient degradation system is constructed, compared with a traditional degradable packaging bag, in the same six-month soil environment test, the degradation rate can be greatly improved by 20-30%, white pollution can be effectively reduced, and the packaging bag has great significance in ecological environment protection and has broad application prospects. And current strict environmental protection regulation requirements and increasingly enhanced environmental protection awareness of people are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of packaging bags, and particularly relates to a naturally degradable PE packaging bag and a preparation process thereof. BACKGROUND

[0002] Traditional polyethylene (PE) packaging bags are widely used in many fields such as food, daily necessities and industrial products due to their good flexibility, moisture resistance and processing performance. However, with the increasing environmental awareness and increasingly stringent environmental regulations, the problem of white pollution caused by the difficulty of natural degradation of traditional PE packaging bags is becoming increasingly prominent. Traditional PE packaging bags can exist in the natural environment for hundreds of years, and a large amount of accumulation not only occupies land resources, but also causes serious damage to the ecological environment such as soil and water, affecting the survival of plants and animals and the ecological balance.

[0003] At present, although there are some degradable packaging bag products on the market, most of them have the following problems: the degradation performance of some degradable packaging bags is poor, and they cannot be effectively degraded within the expected time;

[0004] Some products have poor mechanical properties and cannot meet the actual use requirements;

[0005] Some products have high production costs or complex preparation processes, which limits large-scale production and market promotion;

[0006] In addition, the existing degradable technology mainly focuses on single degradation mode, such as photodegradation or simple biodegradation, and lacks a high-efficiency degradation system with synergistic effect of multiple degradation modes;

[0007] Therefore, a naturally degradable PE packaging bag and a preparation process thereof are needed to solve the above problems. SUMMARY

[0008] The application aims to provide a naturally degradable PE packaging bag and a preparation process thereof to solve the problems in the background.

[0009] To achieve the above-mentioned purpose, the application provides the following technical scheme: a naturally degradable PE packaging bag is composed of the following raw materials in parts by weight: modified polyethylene resin 40-60 parts, polylactic acid 20-30 parts, starch-based degradable material 15-25 parts, nano-cellulose 5-10 parts, biodegradable plasticizer 5-10 parts, antioxidant 0.5-1.5 parts, photoinitiator 0.2-0.8 parts, enzymatic degradation additive 1-3 parts, and microbial carrier particle 2-5 parts.

[0010] The modified polyethylene resin is a polyethylene resin modified by introducing an ester group degradable group. The introduction of the ester group degradable group into the modified polyethylene resin makes the polyethylene main chain more prone to break under certain conditions, creating conditions for chemical degradation.

[0011] Further technical solutions, the grafting rate of ester group degradable groups in the modified polyethylene resin is 2%-4%.

[0012] Further technical solutions, the starch-based degradable material is corn starch modified by hydrophobic modification, and the hydrophobic modification is obtained by reacting corn starch with stearic acid at 120-140℃ for 2-3 hours with a coupling agent as a catalyst.

[0013] Further technical solutions, the biodegradable plasticizer is tributyl citrate, the antioxidant is a hindered phenolic antioxidant, and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0014] Further technical solutions, the enzymatic degradation additive is an inclusion compound of lipase and β-cyclodextrin, and the mass ratio of lipase to β-cyclodextrin is 1: (3-5). The β-cyclodextrin can protect the activity of the lipase, and the lipase can specifically catalyze the hydrolysis of ester groups in a suitable environment to accelerate the degradation of the packaging bag.

[0015] Further technical solutions, the microbial carrier particles contain Bacillus amyloliquefaciens loaded porous diatomite particles, and the microbial loading is 1×10 8 -5×10 8 Bacillus amyloliquefaciens can reproduce in large quantities in the natural environment, secrete various extracellular enzymes, and decompose the starch-based degradable material and polylactic acid components in the packaging bag to achieve microbial degradation. At the same time, polylactic acid and starch-based degradable material have good biodegradability, and the photoinitiator initiates photodegradation reaction under light, and various degradation methods are synergistic, which significantly improves the degradation efficiency of the packaging bag.

[0016] A natural degradable PE packaging bag preparation process is applied to the natural degradable PE packaging bag described above, and comprises the following steps:

[0017] S1, the raw materials are weighed according to the weight fraction;

[0018] S2, the modified polyethylene resin, polylactic acid, starch-based degradable material, nano-cellulose, biodegradable plasticizer, antioxidant, photoinitiator, enzymatic degradation additive and microbial carrier particles are added into a high-speed mixer and mixed at 80-100℃ for 15-25 minutes;

[0019] S3, the mixed material is put into a double-screw extruder for melt extrusion, the extrusion temperature is 160-190℃, and the screw rotation speed is 180-220r / min;

[0020] S4, the extruded material is blown into a film by a film blowing machine, the blow-up ratio is 2-3, the draw ratio is 3-4, and a naturally degradable PE film is prepared; the blow-up ratio and the draw ratio of the film blowing are accurately controlled to regulate the thickness and mechanical properties of the film;

[0021] S5, the naturally degradable PE film is made into a bag by a bag making machine to obtain a naturally degradable PE packaging bag.

[0022] In steps S1-S5, each parameter is optimized and designed to ensure that the raw materials are fully mixed, the material is uniformly plasticized, and the film bag performance is stable.

[0023] In the further technical solution, in the melting and extruding step, the temperature of each zone of the double screw extruder is set as follows: zone 1, 160-165 DEG C; zone 2, 165-175 DEG C; zone 3, 175-185 DEG C; zone 4, 185-190 DEG C; the temperature of each zone of the double screw extruder is reasonably set to ensure the melting effect of the material.

[0024] In the further technical solution, after the film blowing step, the surface of the prepared naturally degradable PE film is treated, the surface treatment method is corona treatment, the treatment voltage is 15-25 kV, and the treatment time is 1-3 s; the surface properties of the film are improved by corona treatment, and the heat sealing parameters are optimized to ensure the bag making quality.

[0025] In the further technical solution, in the bag making step, the heat sealing temperature of the bag making machine is 120-150 DEG C, the heat sealing pressure is 0.2-0.5 MPa, and the heat sealing time is 1-3 s.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] The present application has the advantages of efficient degradation and environmental protection: the degradable groups, enzymatic degradation and microbial degradation are introduced to construct a comprehensive and synergistic efficient degradation system, wherein the ester group introduced in the modified polyethylene resin provides a breakable site for chemical and biological action; the enzymatic degradation additive composed of lipase and beta-cyclodextrin inclusion can specifically catalyze ester hydrolysis; the porous diatomite particles loaded with Bacillus amyloliquefaciens can decompose organic components through extracellular enzymes secreted by microorganisms; the photoinitiator initiates photodegradation under light; the various degradation methods complement each other and exert force from different dimensions of chemistry, biology and photochemistry, so that the packaging bag can be quickly and completely degraded in the natural environment; compared with the traditional degradable packaging bag, the degradation rate can be increased by 20%-30% in the same 6-month soil environment test, which can effectively reduce white pollution and has great significance for ecological environment protection, and meets the current strict environmental protection regulations and the increasing environmental protection awareness of people.

[0028] The application has excellent mechanical properties and wide application range: through scientific and reasonable raw material formula design, nanocellulose effectively enhances the rigidity and toughness of the material, the synergistic effect of polylactic acid and modified polyethylene resin components gives the packaging bag excellent mechanical properties, and through testing, the tensile strength and elongation at break are excellent, which can withstand the packaging of heavy objects and is not easy to break, whether it is used for light packaging of food and daily necessities or heavy load packaging of industrial products, it can easily meet the diversified needs of different fields and different products for packaging strength and flexibility, greatly widening the application range of the product;

[0029] The application has excellent processing performance and is suitable for industrial production: the addition of biodegradable plasticizer significantly improves the processing fluidity of the material, making the entire preparation process smooth and unobstructed, and at the same time, the parameters of the preparation process are finely optimized; from accurately controlling the temperature and time during raw material mixing to ensure uniform dispersion, to precisely setting the temperature of each zone of the twin-screw extruder to achieve full melting and plasticization of the material; from reasonable adjustment of the blow ratio and draw ratio in the film blowing process to ensure the quality of the film, to optimization of the surface properties and bag-making quality of the film through corona treatment and heat sealing parameters, each link is carefully designed, which makes the preparation process suitable for industrial large-scale continuous production, has high production efficiency and low waste rate, can effectively reduce production cost and improve enterprise economic benefit, and lays a solid foundation for large-scale market promotion of the product;

[0030] The application is green and safe, and meets the needs of high-end packaging: in terms of raw material selection, the proportion of biodegradable components is high, and no harmful chemicals are added, and in the natural environment, the degradation products are only carbon dioxide, water and a small amount of biomass, which has no pollution to the environment, truly realizes green environmental protection, and meets the strict requirements of food packaging field on safety, can be used for food, medicine and other products with high safety performance requirements, provides a safe and reliable packaging solution for these high-end fields, and further improves the market value and competitiveness of the product;

[0031] The application has broad market prospects and promotes industry transformation: the packaging bag has many advantages such as high-efficiency degradation, good mechanical properties, excellent processing performance and green safety, and the production cost is relatively low, the wide application of which helps to promote the transformation and upgrading of the packaging industry towards green environmental protection, has significant economic benefits and social benefits, not only can bring rich profit returns to enterprises, but also can contribute to the sustainable development of ecological environment. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The preparation flowchart of the application;

[0033] Figure 2 The performance test chart of the application. DETAILED DESCRIPTION

[0034] The application will be further described in connection with the following examples.

[0035] The following examples are used to illustrate the application but cannot be used to limit the protection scope of the application. The conditions in the examples can be further adjusted according to specific conditions, and simple improvements to the method of the application under the concept of the application all belong to the protection scope of the application.

[0036] Example 1

[0037] 1. The following raw materials are weighed by weight fraction: modified polyethylene resin 40 parts (ester group degradable group grafting rate is 2%), polylactic acid 20 parts, hydrophobically modified corn starch (prepared by reacting corn starch with stearic acid at 120°C for 2 hours with a coupling agent as a catalyst) 15 parts, nano-cellulose 5 parts, tributyl citrate 5 parts, hindered phenolic antioxidant 0.5 parts, 2-hydroxy-2-methyl-1-phenyl-1-propanone 0.2 parts, enzymatic degradation additive with a mass ratio of lipase to β-cyclodextrin of 1:3 1 part, and microbial carrier particles loaded with Bacillus amyloliquefaciens with a microbial loading of 1×10 8 particles per gram of diatomite particles 2 parts;

[0038] 2. The above raw materials are added to a high-speed mixer and mixed at 80°C for 15 minutes;

[0039] 3. The mixed material is put into a twin-screw extruder for melt extrusion, and the temperature of each zone of the twin-screw extruder is set as follows: zone 1 160°C, zone 2 165°C, zone 3 175°C, zone 4 185°C, and the screw rotation speed is 180 r / min;

[0040] 4. The extruded material is blown into a film by a film blowing machine with a blowing ratio of 2 and a pulling ratio of 3;

[0041] 5. The PE film obtained is subjected to corona treatment with a treatment voltage of 15 kV and a treatment time of 1 s;

[0042] 6. The PE film subjected to surface treatment is made into a bag by a bag making machine with a heat sealing temperature of 120°C, a heat sealing pressure of 0.2 MPa, and a heat sealing time of 1 s, to obtain a naturally degradable PE packaging bag.

[0043] Example 2

[0044] 1. The following raw materials are weighed by weight fraction: modified polyethylene resin 50 parts (ester group degradable group grafting rate is 3%), polylactic acid 25 parts, hydrophobically modified corn starch (prepared by reacting corn starch with stearic acid at 130°C for 2.5 hours with a coupling agent as catalyst) 20 parts, nanocellulose 7 parts, tributyl citrate 7 parts, hindered phenolic antioxidant 1 part, 2-hydroxy-2-methyl-1-phenyl-1-propanone 0.5 part, enzymatic degradation additive with a mass ratio of lipase to β-cyclodextrin of 1:4 2 parts, microbial carrier particles containing Bacillus amyloliquefaciens with a microbial loading of 3×10 8

[0045] 2. The above raw materials are added to a high-speed mixer and mixed at 90°C for 20 minutes;

[0046] 3. The mixed material is fed into a twin-screw extruder for melt extrusion, with the temperature settings of the twin-screw extruder being: zone 1 162°C, zone 2 170°C, zone 3 180°C, zone 4 188°C, and the screw rotation speed being 200 r / min;

[0047] 4. The extruded material is blown into a film by a film blowing machine with a blow-up ratio of 2.5 and a draw ratio of 3.5;

[0048] 5. The PE film obtained is subjected to corona treatment with a treatment voltage of 20 kV and a treatment time of 2 s;

[0049] 6. The PE film subjected to surface treatment is made into a bag by a bag making machine with a heat sealing temperature of 135°C, a heat sealing pressure of 0.3 MPa, and a heat sealing time of 2 s, to obtain a naturally degradable PE packaging bag.

[0050] Example 3

[0051] 1. The following raw materials are weighed by weight fraction: modified polyethylene resin 60 parts (ester group degradable group grafting rate is 4%), polylactic acid 30 parts, hydrophobically modified corn starch (prepared by reacting corn starch with stearic acid at 140°C for 3 hours with a coupling agent as catalyst) 25 parts, nanocellulose 10 parts, tributyl citrate 10 parts, hindered phenolic antioxidant 1.5 parts, 2-hydroxy-2-methyl-1-phenyl-1-propanone 0.8 part, enzymatic degradation additive with a mass ratio of lipase to β-cyclodextrin of 1:5 3 parts, microbial carrier particles containing Bacillus amyloliquefaciens with a microbial loading of 5×10 8

[0052] 2. The above raw materials are added to a high-speed mixer and mixed at 100°C for 25 minutes;

[0053] ​​3. The mixed material is put into a double screw extruder for melt extrusion, and the temperature of each zone of the double screw extruder is set as follows: 165℃ for the first zone, 175℃ for the second zone, 185℃ for the third zone, and 190℃ for the fourth zone, and the screw rotation speed is 220r / min;

[0054] 4. The extruded material is blown into a film by a film blowing machine, and the blow-up ratio is 3 and the draw ratio is 4;

[0055] 5. The prepared PE film is subjected to corona treatment, and the treatment voltage is 25kV and the treatment time is 3s;

[0056] 6. The PE film subjected to surface treatment is made into a bag by a bag making machine, and the heat sealing temperature is 150℃, the heat sealing pressure is 0.5MPa, and the heat sealing time is 3s, thereby obtaining a naturally degradable PE packaging bag.

[0057] The naturally degradable PE packaging bag prepared in the above embodiment is subjected to performance test, and the results are as follows: the prepared naturally degradable PE packaging bag has excellent mechanical properties and degradation performance, and can meet the actual market demand and environmental protection requirements.

[0058] Although the embodiments of the present application have been shown and described, it is understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A naturally degradable PE packaging bag, characterized by: The modified polyethylene resin is a polyethylene resin modified by introducing an ester group degradable group. The grafting rate of the ester group degradable group in the modified polyethylene resin is 2%-4%.

2. The naturally degradable PE packaging bag according to claim 1, characterized in that: The starch-based degradable material is corn starch subjected to hydrophobic modification, and the hydrophobic modification is prepared by reacting corn starch with stearic acid at 120-140℃ for 2-3 hours with a coupling agent as a catalyst.

3. The naturally degradable PE packaging bag according to claim 1, characterized in that: The biodegradable plasticizer is tributyl citrate, the antioxidant is a hindered phenolic antioxidant, and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

4. The naturally degradable PE packaging bag according to claim 1, characterized in that: The enzymatic degradation additive is an inclusion compound of lipase and β-cyclodextrin, and the mass ratio of lipase to β-cyclodextrin is 1: (3-5).

5. The naturally degradable PE packaging bag according to claim 1, characterized in that: The method comprises the following steps:

6. The naturally degradable PE packaging bag according to claim 1, characterized in that: The microorganism-containing carrier particles are porous diatomite particles loaded with Bacillus amyloliquefaciens, the microorganism loading being 1 x 10 8 -5 x 10 8 bacterial cells per gram of diatomite particles.

7. A process for preparing a naturally degradable PE packaging bag, applied to the naturally degradable PE packaging bag according to any one of claims 1-6, characterized in that: S1, taking each raw material by weight fraction; S2, adding the modified polyethylene resin, polylactic acid, starch-based degradable material, nanocellulose, biodegradable plasticizer, antioxidant, photoinitiator, enzymatic degradation additive and microbial carrier-containing particles into a high-speed mixer and mixing at 80-100℃ for 15-25 minutes; S3, melting and extruding the mixed material in a twin-screw extruder, the extrusion temperature is 160-190℃, and the screw rotation speed is 180-220r / min; S4, blowing the extruded material through a film blowing machine, the blow ratio is 2-3, and the draw ratio is 3-4, to obtain a naturally degradable PE film; S5, making the naturally degradable PE film into a bag through a bag making machine to obtain a naturally degradable PE packaging bag. In the melting and extruding step, the temperature of each zone of the twin-screw extruder is set as follows: zone 1, 160-165℃; zone 2, 165-175℃; zone 3, 175-185℃; and zone 4, 185-190℃.

8. The process for the preparation of naturally degradable PE packaging bags as claimed in claim 7, wherein: After the film blowing step, the naturally degradable PE film obtained is subjected to surface treatment, and the surface treatment method is corona treatment, the treatment voltage is 15-25kV, and the treatment time is 1-3s.

9. The process for the preparation of naturally degradable PE packaging bags as claimed in claim 7, wherein: In the bag making step, the heat sealing temperature of the bag making machine is 120-150℃, the heat sealing pressure is 0.2-0.5MPa, and the heat sealing time is 1-3s.

10. The process for the preparation of naturally degradable PE packaging bags as claimed in claim 7, wherein: ​

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