Puncture-resistant biodegradable film bag and preparation method thereof

Abstract

The invention discloses a puncture-resistant biodegradable film bag and a preparation method thereof. The puncture-resistant biodegradable film bag is prepared from the following raw materials in parts by weight: 50-80 parts of biodegradable polyester, 1-20 parts of a modifier and 10-35 parts of an inorganic filler, wherein the total part number of the three raw materials is 100; the composition further comprises 0.1-5 parts of a cross-linking agent, 0.1-5 parts of an antioxidant and 0.1-1 part of a dispersing agent; the weight-average molecular weight of the puncture-resistant biodegradable material is 100,000-300,000; and the cross-linking agent is at least one of triallyl isocyanurate, trimethylallyl isocyanate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and triglycidyl tripolyisocyanate. The modifier, the cross-linking agent and the biodegradable polyester have a synergistic effect, and through an electron beam irradiation process, not only can the puncture strength of the film bag be greatly improved, but also the MD tensile strength and the TD tensile strength are also greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of biodegradable materials, and particularly relates to a puncture-resistant biodegradable film bag and a preparation method thereof. Background Art

[0002] In recent years, plastics have been widely used due to their excellent performance. At the same time, more and more plastic waste has been generated. If plastic waste is not handled properly, it will cause great harm to the environment. In order to solve these problems, countries have successively introduced relevant policies to restrict the use of traditional petroleum-based plastics and list bio-based materials as strategic new development industries. With the sustainable development of society, people pay more and more attention to environmental protection. The development of fully biodegradable film bags has become an inevitable trend. Using fully biodegradable film bags to replace ordinary petrochemical plastics can effectively reduce the "white pollution" problem caused by traditional plastics to the environment.

[0003] Biodegradable materials refer to materials whose molecular chains can be decomposed by microorganisms (such as bacteria, mold, algae, etc.) in garbage disposal or natural environment to produce pollution-free water, carbon dioxide or methane.

[0004] Polylactic acid (PLA) has a wide range of sources and low cost. At the same time, due to its good processing performance, chemical inertness, biodegradability and good biocompatibility, its degradation occurs under industrial composting conditions, and the final products of complete degradation are carbon dioxide and water, which are pollution-free to the environment and human body, making it a very promising green thermoplastic polymer material and has received extensive attention and research in various fields. This advantage makes PLA have higher tensile strength and tensile modulus, but defects such as high hardness and poor toughness limit its application range.

[0005] PBAT is a copolymer of butylene adipate and butylene terephthalate. It is a thermoplastic biodegradable plastic that has the characteristics of both PBA and PBT. It has good ductility and elongation at break, good heat resistance and impact resistance, and excellent biodegradability. PBAT production capacity is the third largest biodegradable plastic after starch-based plastics and PLA. It is one of the most popular biodegradable materials in biodegradable plastic research and the best market application.

[0006] However, film bag products must meet other performance requirements, including puncture strength, tensile strength, nominal strain at break, heat-sealing strength, etc. Only films that meet the above performance requirements can be used for film bag products. Especially in terms of puncture strength, the existing biodegradable film bags usually have weak puncture strength performance.

[0007] Patent document CN103589124A discloses a biodegradable PLA / PBAT composite film and a preparation method thereof. The composite film is prepared from polylactic acid, PBAT, and filler. The preparation process of this blend is simple, but when using this material to make film bags, problems such as poor film dispersion, rough surface, and poor mechanical properties will occur.

[0008] Patent document CN109810476A discloses a fully biodegradable film bag composed of PBAT, PLA, modified fillers, etc. The modified additives are silane coupling agents, aluminate coupling agents, titanate coupling agents, etc., and the performance optimization of the film bag in terms of puncture strength is not involved.

[0009] Patent document CN112662147A discloses a high-performance ternary composite biodegradable film, which includes the following substances in parts by weight: 50-90 parts of poly(butylene terephthalate-succinate-butylene glycol), 5-30 parts of polylactic acid, 5-20 parts of vinyl acetate copolymer, 0.1-1.0 parts of crosslinking agent, 0.1-0.5 parts of lubricant, 0.1-0.3 parts of opening agent, 0.1-0.3 parts of plasticizer, and 0.1-0.5 parts of composite stabilizer; the melt index of the vinyl acetate copolymer is 15.4g / 10min (150℃, 2.16kg); the chain extender is polyphenyl polymethylene polyisocyanate. However, the main function of the poly(butylene terephthalate-succinate-butylene glycol) and vinyl acetate copolymer in this document is to improve the heat sealing performance of the film, and the performance optimization of the film bag puncture strength is not involved.

[0010] Patent document CN115593061A discloses a high-barrier biodegradable composite film, comprising an outer film, an intermediate film and an inner film, wherein the inner film comprises the following components in parts by weight: 5-15 parts of polylactic acid, 80-90 parts of poly(butylene terephthalate-adipate), 2-4 parts of a compatibilizer, and 0.5-3 parts of a chain extender; the outer film comprises the following components in parts by weight: 20-65 parts of polylactic acid, 60-70 parts of poly(butylene terephthalate-adipate), 2-4 parts of a compatibilizer, and 0.5-3 parts of a chain extender; the compatibilizer is composed of ethylene-methyl acrylate-glycidyl methacrylate copolymer and polyvinyl acetate in a mass ratio of 1.5-2.5:1, and the chain extender is a copolymer ADR4468 containing an epoxy functional group. However, the main function of the polyhydroxyalkanoates, polymethyl ethylene carbonate and polycaprolactone of the middle layer film in this document is to improve the barrier properties of the film, and the performance optimization of the puncture strength of the film bag is not involved.

[0011] Patent document CN117209983A discloses a highly transparent and tearable biodegradable film, the formula of which is as follows: 85-98 parts of polylactic acid, 2-10 parts of ethylene-vinyl acetate copolymer, 1-5 parts of plasticizer, 0.1-0.5 parts of chain extender, 0.1-1 parts of lubricant, 0.1-0.6 parts of antioxidant; the number average molecular weight of polylactic acid is 50,000-200,000 Daltons; the plasticizer is isosorbide di-n-hexanoate; the chain extender is styrene-acrylic acid-methacrylate glycidyl ester copolymer; the lubricant is erucamide. However, the main raw material resin EVA in this document is used to maintain the transparency of PLA film and improve the heat-sealing strength, and the performance optimization of the film bag puncture strength is not involved.

[0012] In view of the above situation, there is an urgent need to develop a new puncture-resistant biodegradable film bag to meet the needs of practical use. Summary of the invention

[0013] The object of the present invention is to provide a puncture-resistant biodegradable film bag and a preparation method thereof, so as to solve the problem that the biodegradable film bags in the prior art generally have relatively weak puncture strength performance.

[0014] In order to achieve the above object, the technical solution of the present invention is:

[0015] The puncture-resistant biodegradable film bag of the present invention is made of the following raw materials in parts by weight: 50-80 parts of biodegradable polyester, 1-20 parts of modifier, 10-35 parts of inorganic filler, and the total parts of the three raw materials is 100 parts; it also includes 0.1-5 parts of cross-linking agent, 0.1-5 parts of antioxidant and 0.1-1 parts of dispersant; the weight average molecular weight of the puncture-resistant biodegradable material is 100,000-300,000;

[0016] The biodegradable polyester is at least one of polybutylene terephthalate / butylene adipate copolymer (PBAT) and polylactic acid (PLA); the melt flow rate at 190° C. and 2.16 kg is 3 to 10 g / 10 min;

[0017] The modifier is ethylene-vinyl acetate copolymer (EVA), the melt flow rate at 190°C and 2.16kg is 2-4g / 10min; the vinyl acetate (VA) content is 15-25%;

[0018] The crosslinking agent is at least one of triallyl isocyanurate, trimethallyl isocyanate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and triglycidyl isocyanurate;

[0019] The antioxidant is at least one of a hindered phenol antioxidant or a phosphite antioxidant;

[0020] The inorganic filler is one or more of talc, mica, calcium carbonate, and montmorillonite, and the mesh number is 1000 to 5000 mesh;

[0021] The dispersant is one of stearamide, vinyl bisstearamide, stearic acid monoglyceride, and PE wax. The dispersant is used to improve the dispersibility of the filler in the film blowing process and improve the surface appearance of the film bag product.

[0022] The method for preparing a puncture-resistant biodegradable film bag of the present invention comprises the following steps:

[0023] S1, mixing the dried biodegradable polyester with the antioxidant, inorganic filler, modifier and dispersant in a high-speed mixer to obtain a premix;

[0024] S2, adding the premix into a twin-screw extruder from a main feed port, heating the cross-linking agent to 115-125° C., and adding the premix into the twin-screw extruder from a side feed port by liquid injection;

[0025] S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperature of the twin-screw extruder from the feed port to the die head is 100-190°C;

[0026] S4, adding the modified particles into a film blowing machine for film blowing, and the rolled film is bagged, glue sprayed, slit and packaged to obtain a biodegradable film bag;

[0027] S5, irradiating the biodegradable film bag under the irradiation of an electron beam with an irradiation dose of 10 to 100 kGy to obtain the puncture-resistant biodegradable film bag.

[0028] Preferably, in step S4, the temperature of zones 1 to 6 of the film blowing machine is 100-180°C, and the die head temperature is 130-190°C.

[0029] The puncture-resistant biodegradable film bag of the present invention has good puncture strength and can be used to replace PE-type film bag material products; it is used to make blown film bag products, such as garbage bags, vest bags, express bags, bone strip bags, zipper bags and / or roll bags, etc.

[0030] Compared with the prior art, the present invention has the following positive effects:

[0031] 1. The modifier EVA used in the present invention has good softness, rubber-like elasticity and good chemical stability, good anti-aging, and non-toxicity. It can improve the miscibility of biodegradable polyester and filler, so that the molding processability of the final film bag product is improved.

[0032] 2. The modifier, cross-linking agent and biodegradable polyester used in the present invention have a synergistic effect. Under a high-energy electron beam, a hydrogen abstraction reaction can occur to generate alkyl free radicals or allyl free radicals. The free radicals on the molecular chain combine with each other to form an H-type or T-type crosslink, that is, two alkyl free radicals combine with each other to form an H-type crosslink, and the alkyl free radicals and the free radicals on the surface of the inorganic filler and the end of the polymer molecular chain combine with each other to form a T-type crosslink.

[0033] 3. The electron beam irradiation process is used to form a three-dimensional network structure of the molecular chain of the biodegradable film bag film, thereby improving the puncture force performance of the biodegradable film bag. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the processing process of the present invention. DETAILED DESCRIPTION

[0035] Those skilled in the art should recognize that the present embodiment is only used to illustrate the present invention, and is not used to limit the present invention. Any changes or modifications to the embodiment within the scope of the present invention are within the scope of the claims of the present invention.

[0036] Example 1

[0037] The raw materials and weight parts of the puncture-resistant biodegradable film bag of Example 1 are listed in Table 1, wherein the melt flow rate of the biodegradable polyester PBAT is 5 g / 10 min (190° C. / 2.16 kg); the particle size of the inorganic filler talc is 2000 mesh; the melt flow rate of the modifier EVA is 2.5 g / 10 min (190° C. / 2.16 kg), and the VA content is 15%; the processing technology is as follows: Figure 1 As shown, the following steps are included:

[0038] S1, mixing the biodegradable polyester dried at 80° C. for 4 hours with an antioxidant, an inorganic filler, a modifier and a dispersant in a high-speed mixer to obtain a premix;

[0039] S2, adding the premix into the twin-screw extruder from the main feed port; heating the cross-linking agent to 120°C and adding it into the twin-screw extruder from the side feed port by liquid injection;

[0040] S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperatures of zones 1 to 10 of the twin-screw extruder are 100° C., 160° C., 160° C., 160° C., 160° C., 160° C., 160° C., 160° C., 160° C., and 160° C., respectively, and the die temperature is 160° C.;

[0041] S4, adding the modified particles into a film blowing machine, the temperatures of zones 1 to 6 of the film blowing machine are 100°C, 160°C, 160°C, 160°C, 160°C, 160°C, and the die head temperature is 170°C, and the wound film is subjected to bag making, glue spraying, slitting, and packaging processes to obtain biodegradable film bags.

[0042] S5, irradiating the biodegradable film bag under the irradiation of an electron beam with an irradiation dose of 15 kGy to obtain a puncture-resistant biodegradable film bag.

[0043] Table 1 Raw material formula of Examples 1 to 4 and Comparative Examples, unit: weight parts

[0044]

[0045]

[0046] Example 2

[0047] The raw materials and weight parts of the puncture-resistant biodegradable film bag of Example 2 are listed in Table 1, wherein the melt flow rate of the biodegradable polyester PBAT is 4 g / 10 min (190°C / 2.16 kg); the particle size of the inorganic filler calcium carbonate is 1250 mesh; the melt flow rate of the modifier EVA is 2.5 g / 10 min (190°C / 2.16 kg), and the VA content is 18%; the processing technology is as follows Figure 1 As shown, the following steps are included:

[0048] S1, mixing the biodegradable polyester dried at 80° C. for 4 hours with the antioxidant, inorganic filler, modifier and dispersant in a high-speed mixer to obtain a premix;

[0049] S2, adding the premix into the twin-screw extruder from the main feed port, heating the cross-linking agent to 120°C, and adding the premix into the twin-screw extruder from the side feed port by liquid injection;

[0050] S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperatures of zones 1 to 10 of the twin-screw extruder are 100° C., 150° C., 150° C., 150° C., 150° C., 150° C., 150° C., 150° C., 150° C., and 150° C., respectively, and the die temperature is 150° C.;

[0051] S4, adding the modified particles into a film blowing machine, the temperatures of zones 1 to 6 of the film blowing machine are 100°C, 170°C, 170°C, 170°C, 170°C, 170°C, and the die head temperature is 170°C, and the wound film is subjected to bag making, glue spraying, slitting, and packaging processes to obtain biodegradable film bags.

[0052] S5, irradiating the biodegradable film bag with an electron beam having an irradiation dose of 20 kGy to obtain a puncture-resistant biodegradable film bag.

[0053] Example 3

[0054] The raw materials and weight parts of the puncture-resistant biodegradable film bag of Example 3 are listed in Table 1, wherein the melt flow rate of the biodegradable polyester PBAT is 4 g / 10 min (190°C / 2.16 kg), the melt flow rate of PLA is 3.2 g / 10 min (190°C / 2.16 kg); the particle size of the inorganic filler calcium carbonate is 5000 mesh; the melt flow rate of the modifier EVA is 2.5 g / 10 min (190°C / 2.16 kg), and the VA content is 20%; the processing technology is as follows Figure 1 As shown, the following steps are included:

[0055] S1, mixing the biodegradable polyester dried at 80° C. for 4 hours with the antioxidant, inorganic filler, modifier and dispersant in a high-speed mixer to obtain a premix;

[0056] S2, adding the premix into the twin-screw extruder from the main feed port; heating the cross-linking agent to 120°C and adding it into the twin-screw extruder from the side feed port by liquid injection;

[0057] S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperatures of zones 1 to 10 of the twin-screw extruder are 100° C., 150° C., 170° C., 170° C., 170° C., 170° C., 170° C., 170° C., 170° C., and 170° C., respectively, and the die temperature is 170° C.;

[0058] S4, adding the modified particles into a film blowing machine, the temperatures of zones 1 to 6 of the film blowing machine are 100°C, 170°C, 170°C, 170°C, 170°C, 170°C, and the die head temperature is 170°C, and the wound film is subjected to bag making, glue spraying, slitting, and packaging processes to obtain biodegradable film bags.

[0059] S5, irradiating the biodegradable film bag with an electron beam having an irradiation dose of 10 kGy to obtain a puncture-resistant biodegradable film bag.

[0060] Example 4

[0061] The raw materials and weight parts of the puncture-resistant biodegradable film bag of Example 4 are listed in Table 1, wherein the melt flow rate of the biodegradable polyester PBAT is 3.5 g / 10 min (190°C / 2.16 kg), and the melt flow rate of PLA is 5.5 g / 10 min (190°C / 2.16 kg); the particle size of the inorganic filler calcium carbonate is 3000 mesh, montmorillonite, 10 parts, 5000 mesh; the melt flow rate of the modifier EVA is 2.5 g / 10 min (190°C / 2.16 kg), and the VA content is 22%; the processing technology is as follows: Figure 1 As shown, the following steps are included:

[0062] S1, mixing the biodegradable polyester dried at 80° C. for 4 hours with the antioxidant, inorganic filler, modifier and dispersant in a high-speed mixer to obtain a premix;

[0063] S2, adding the premix into the twin-screw extruder from the main feed port; heating the cross-linking agent to 120°C and adding it into the twin-screw extruder from the side feed port by liquid injection;

[0064] S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperatures of zones 1 to 10 of the twin-screw extruder are 100° C., 150° C., 170° C., 170° C., 170° C., 170° C., 170° C., 170° C., 170° C., and 170° C., respectively, and the die temperature is 170° C.;

[0065] S4, adding the modified particles into a film blowing machine, the temperatures of zones 1 to 6 of the film blowing machine are 100°C, 170°C, 170°C, 170°C, 170°C, 170°C, and the die head temperature is 170°C, and the wound film is subjected to bag making, glue spraying, slitting, and packaging processes to obtain biodegradable film bags.

[0066] S5, irradiating the biodegradable film bag with an electron beam having an irradiation dose of 30 kGy to obtain a puncture-resistant biodegradable film bag.

[0067] Comparative Example 1

[0068] The raw materials and preparation process of Comparative Example 1 are the same as those of Example 1, except that: there is no modifier and cross-linking agent in the raw materials, and there is no irradiation in step S5 during the preparation process.

[0069] Comparative Example 2

[0070] The raw materials and preparation process of Comparative Example 2 are the same as those of Example 1, except that there is no cross-linking agent in the raw materials and there is no irradiation in step S5 during the preparation process.

[0071] Comparative Example 3

[0072] The raw materials and preparation process of Comparative Example 3 are the same as those of Example 1, except that there is no irradiation in step S5 during the preparation process.

[0073] Detection experiment example

[0074] The film bags of Examples 1 to 4 and Comparative Examples 1 to 3 were tested, and the MD tensile strength, MD elongation at break, TD tensile strength and TD elongation at break were measured in accordance with standard GB / T1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for thin plastics and sheets"; the puncture strength was measured in accordance with standard GB / T10004-2008 "Plastic composite films, bags - dry composite, extrusion composite for packaging"; the performance results are shown in Table 1.

[0075] Table 2 Test results of Examples 1 to 4 (film thickness is 50 um),

[0076]

[0077] It can be seen from Table 2 that the modifier, cross-linking agent and biodegradable polyester used in the present invention have a synergistic effect. After the electron beam irradiation process, the molecular chains of the biodegradable film bag film of the present invention form a three-dimensional network structure, which can not only greatly improve the puncture strength of the film bag, but also greatly improve the MD tensile strength and TD tensile strength.

[0078] The production process of the invention is simple, can effectively improve the performance of the biodegradable film bag, and can effectively reduce the environmental pollution caused by the production and use of traditional non-biodegradable film bags.

Claims

1. A puncture-resistant biodegradable film bag, characterized in that: The material is made of the following raw materials in parts by weight: 50-80 parts of biodegradable polyester, 1-20 parts of modifier, 10-35 parts of inorganic filler, and the total parts of the three raw materials is 100 parts; it also includes 0.1-5 parts of cross-linking agent, 0.1-5 parts of antioxidant and 0.1-1 parts of dispersant; the weight average molecular weight of the puncture-resistant biodegradable material is 100,000-300,000; The crosslinking agent is at least one of triallyl isocyanurate, trimethallyl isocyanate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and triglycidyl isocyanurate.

2. The puncture-resistant biodegradable film bag according to claim 1, characterized in that: The biodegradable polyester is at least one of polybutylene terephthalate / butylene adipate copolymer and polylactic acid; the melt flow rate at 190° C. and 2.16 kg is 3-10 g / 10 min.

3. The puncture-resistant biodegradable film bag according to claim 1, characterized in that: The modifier is ethylene-vinyl acetate copolymer, the melt flow rate of which is 2-4 g / 10 min at 190° C. and 2.16 kg, and the vinyl acetate content is 15-25%.

4. The puncture-resistant biodegradable film bag according to claim 1, characterized in that: The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

5. The puncture-resistant biodegradable film bag according to claim 1, characterized in that: The inorganic filler is one or more of talc, mica, calcium carbonate and montmorillonite, and has a mesh size of 1000 to 5000 meshes.

6. The puncture-resistant biodegradable film bag according to claim 1, characterized in that: The dispersant is one of stearamide, vinyl bisstearamide, stearic acid monoglyceride and PE wax.

7. The method for preparing a puncture-resistant biodegradable film bag according to claim 1, characterized in that: The following steps are involved: S1, mixing the dried biodegradable polyester with the antioxidant, inorganic filler, modifier and dispersant in a high-speed mixer to obtain a premix; S2, adding the premix into a twin-screw extruder from a main feed port, heating the cross-linking agent to 115-125° C., and adding the premix into the twin-screw extruder from a side feed port by liquid injection; S3, extruding, cooling and pelletizing through a twin-screw extruder to obtain modified particles; the temperature of the twin-screw extruder from the feed port to the die head is 100-190°C; S4, adding the modified particles into a film blowing machine for film blowing, and the rolled film is bagged, glue sprayed, slit and packaged to obtain a biodegradable film bag; S5, irradiating the biodegradable film bag under the irradiation of an electron beam with an irradiation dose of 10 to 100 kGy to obtain the puncture-resistant biodegradable film bag.

8. The method for preparing a puncture-resistant biodegradable film bag according to claim 7, characterized in that: In step S4, the temperature of zones 1 to 6 of the film blowing machine is 100-180°C, and the die head temperature is 130-190°C.

9. The use of the puncture-resistant biodegradable film bag according to claim 1, characterized in that: Used to make blown film bags.

Images