A high-toughness biodegradable material for film blowing and preparation method thereof

Abstract

The invention discloses a high-toughness biodegradable material for film blowing and a preparation method thereof, which belongs to the technical field of biodegradable materials. By weight, the composition is as follows, including: 50-60 parts of polyethylene, 8-16 parts of polybutylene adipate terephthalate, 6-12 parts of polylactic acid, 4-9 parts of homemade nano-silicon dioxide modified lignin, 3-8 parts of modified nano-calcium carbonate, 1-2 parts of plasticizer, 3-5 parts of compatibilizer, 0.2-1 parts of lubricant, 0.3-1.5 parts of carbon black, and 0.2-0.8 parts of antioxidant. The material for film blowing of the present application, through the composite use of homemade nano-silicon dioxide modified lignin and modified nano-calcium carbonate, makes the material have super high toughness, and the addition of polybutylene adipate terephthalate, polylactic acid, and lignin has a positive effect on the biodegradability of the material, thereby achieving a better biodegradation effect.

Description

Technical Field

[0001] The invention belongs to the technical field of biodegradable materials, and specifically relates to a high-toughness biodegradable material for film blowing molding and a preparation method thereof. Background Art

[0002] Biodegradable materials have become an important alternative to traditional petroleum-based plastics because they can decompose in the natural environment and reduce negative impacts on the environment.

[0003] Driven by the "plastic restriction" and "plastic ban" policies and regulations in countries around the world, biodegradable plastic packaging films have replaced traditional plastic packaging films and become one of the important ways to solve the problem of white pollution.

[0004] As a common plastic processing method, blown film molding technology is widely used in packaging materials, films and other fields. In this context, research and development of biodegradable materials with high toughness for blown film molding has become an important direction of current materials science and environmental protection technology.

[0005] In recent years, some relatively low-priced biodegradable plastics such as PLA, PBAT, PPC, and PBS have been used as substitutes for traditional plastic packaging films. They are processed into films through blown film molding by combining physical and / or chemical modification methods, and have achieved certain practical application effects in the fields of food, medical care, and chemical industry.

[0006] For example, the Chinese invention patent with application number: CN201910660871.9 discloses a base resin for blow-molded degradable film and a blow-molded degradable film, and discloses a base resin for blow-molded degradable film, wherein the base resin is made from raw materials including the following components by mass: 5-60 parts of poly-L-lactic acid, 30-95 parts of adipic acid-terephthalic acid-butylene glycol copolymer, 0.2-5 parts of foaming regulator, 0.1-2 parts of reactive compatibilizer, and 1-5 parts of diol oligomer. The above-mentioned prior art mainly reduces the surface density while ensuring the mechanical properties by adding reactive compatibilizer, thereby reducing the cost, rather than improving the toughness of the material.

[0007] There is also a Chinese invention patent with application number: CN201610662339.7, which discloses a film made of calcium carbonate and a method for manufacturing the same. The calcium carbonate selected is a light calcium carbonate with a particle size of 3000 mesh. In actual application, the fixed mesh size has certain problems. As the formula changes, if the mesh size is large, the CaCO3 particles may not be easily dispersed evenly during the extrusion and blow molding process, resulting in an uneven microstructure of the film, affecting the overall performance of the film. Smaller particle size CaCO3 may have weaker interfacial interaction with the polymer matrix, resulting in easy destruction of the interface when subjected to external force, thereby reducing the overall tensile strength and tear strength. Even through the use of compound CaCO3 particle size, the above defects may still exist.

[0008] There is still much room for improvement in the resilience of existing technologies; therefore, there is an urgent need to introduce new process technologies to solve the above problems and seek more feasible solutions. Summary of the invention

[0009] In order to solve the defects existing in the above technical solutions, the purpose of the present invention is to provide a high-toughness biodegradable material for blown film molding and a preparation method thereof; the purpose of the present invention can be achieved by the following technical solution: a high-toughness biodegradable material for blown film molding, comprising the following components by weight: 50-60 parts of polyethylene, 8-16 parts of polybutylene adipate terephthalate, 6-12 parts of polylactic acid, 4-9 parts of homemade nano-silicon dioxide modified lignin, 3-8 parts of modified nano-calcium carbonate, 1-2 parts of plasticizer, 3-5 parts of compatibilizer, 0.2-1 part of lubricant, 0.3-1.5 parts of carbon black, and 0.2-0.8 parts of antioxidant.

[0010] The plasticizer is acetyl tributyl citrate;

[0011] The compatibilizer is maleic anhydride;

[0012] The lubricant is one or more of triglycerol monostearate, triglycerol distearate, and pentaerythritol stearate;

[0013] The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate or a combination of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate and didodecyl thiodipropionate.

[0014] The preparation method of the homemade nano-silicon dioxide modified lignin comprises the following steps: dispersing nano-silicon dioxide in anhydrous ethanol, and then adding N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane to the mixed solution; realizing amino modification of the nano-silicon dioxide by magnetic stirring at room temperature for 1.5 hours; then dissolving epoxy resin in anhydrous acetone at room temperature to prepare a solution, adding dry nano-lignin to the solution after the epoxy resin is completely dissolved, maintaining magnetic stirring at room temperature, and continuing the reaction for 3 hours, then purifying the nano-lignin by high-speed centrifugation, washing the purified nano-lignin with acetone for more than 3 times, and then drying with nitrogen, then immersing the epoxy resinized nano-lignin in the homemade nano-silicon dioxide solution, maintaining for 1.5 hours, purifying the modified nano-lignin by centrifugation, and washing the product with ethanol; then adding ethanol to the modified nano-lignin, and then placing it under an ultrasonic crusher for 5 minutes to make it evenly dispersed, and finally drying it with nitrogen, so as to prepare the homemade nano-silicon dioxide modified lignin.

[0015] Modified nano-calcium carbonate: Nano-calcium carbonate is prepared by an emulsion method. CaCl2 and Na2CO3 are taken and placed in a beaker respectively, and deionized water is added to prepare a solution; the beaker containing the solution is placed in a constant temperature water bath and preheated to 40°C. The two solutions are quickly mixed under mechanical stirring conditions and then aged for 5 minutes under ultrasonic conditions; finally, the precipitate is filtered, washed, and dried to prepare nano-calcium carbonate; nano-calcium carbonate is taken, diluted with distilled water, and ultrasonically dispersed for 1 hour, then transferred to a three-necked flask, phenylalanine is added, and ultrasonically dispersed for 1 hour; placed in a constant temperature water bath, heated to 70°C, stirred at a rate of 1200rad / min, and reacted for 2 hours. After the reaction is completed, the product is filtered, washed, and vacuum dried to prepare modified nano-calcium carbonate.

[0016] The invention discloses a method for preparing a biodegradable material for film blowing molding with high toughness. The method comprises the following steps: weighing polyethylene, polybutylene adipate terephthalate, polylactic acid, self-made nano-silicon dioxide modified lignin, modified nano-calcium carbonate, plasticizer, compatibilizer, lubricant, carbon black and antioxidant in proportion; mixing the above ingredients uniformly and then subjecting the mixture to vacuum drying treatment; after drying, sending the mixture to a heating system for plasticization treatment; subjecting the plasticized mixture to secondary sol molding by a booster screw to completely fuse the mixture together; then subjecting the fusion to high-pressure multi-hole extrusion wire drawing molding, with an extrusion pressure of 3-4Mpa; subjecting the extruded fusion to qualitative treatment by a multi-stage cooling system, and then subjecting the extruded fusion to high-speed slicing into particles, and finally drying for standby use, so as to prepare a biodegradable material for film blowing molding with high toughness.

[0017] During the preparation process, the temperature of the plasticizing treatment is set at 200-210 degrees Celsius.

[0018] The present invention has the beneficial effects:

[0019] 1. The homemade nano-silica modified lignin introduced in the material of the present application adopts N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane amino-modified nano-silica, which can not only form hydrogen bonds with functional groups such as hydroxyl groups in lignin, but also form chemical bonds with the matrix in the degradation material, significantly enhancing the interface bonding force and improving the interface compatibility; making the stress transfer between the matrix and the homemade nano-silica modified lignin easier, and not easy to produce fatigue limit caused by defects during stretching; and the lignin modified by the homemade nano-silica can also adjust the particle polarity of the nano-lignin, giving it a more hydrophobic property, and by virtue of its volume effect and quantum tunneling effect, it can produce a penetration effect, can penetrate into the π bond attachment of the polymer compound, overlap with its electron cloud, form a spatial network structure, and thus greatly improve the toughness of the material;

[0020] 2. The present application introduces phenylalanine-modified nano-calcium carbonate, in which the carboxyl group can be chemically bonded with the calcium ions in the nano-calcium carbonate; and the steric hindrance of phenylalanine itself is also conducive to improving the dispersion of nano-calcium carbonate. Nano-calcium carbonate itself exhibits a toughening effect of rigid particles. After modification, the compatibility between nano-calcium carbonate and the substrate is further improved, the combination is more tightly, and a certain strength of interfacial adhesion is generated between the inorganic particles, which can weaken the interaction between the polymer chains, making the movement of the polymer chains easier, and the elongation at break is improved, so that it has high toughness;

[0021] 3. The blown film molding material of the present application has super high toughness through the compound use of homemade nano-silica modified lignin and modified nano-calcium carbonate, and the addition of polybutylene adipate terephthalate, polylactic acid and lignin has a positive effect on the biodegradability of the material, thereby achieving a better biodegradation effect. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, and the illustrative embodiments of the present invention and its description are only used to explain the present invention, and are not used as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper limit and lower limit of these smaller ranges can be independently included or excluded in the scope.

[0023] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0024] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] The "parts" indicated in the following examples are all parts by weight.

[0027] Example 1

[0028] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 50 parts of polyethylene, 8 parts of polybutylene adipate terephthalate, 6 parts of polylactic acid, 4 parts of homemade nano-silicon dioxide modified lignin, 3 parts of modified nano-calcium carbonate, 1 part of plasticizer, 3 parts of compatibilizer, 0.2 parts of lubricant, 0.3 parts of carbon black, and 0.2 parts of antioxidant;

[0029] The plasticizer is acetyl tributyl citrate;

[0030] The compatibilizer is maleic anhydride;

[0031] The lubricant is a mixture of triglycerol monostearate and pentaerythritol stearate;

[0032] The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate;

[0033] The preparation method of the homemade nano-silicon dioxide modified lignin is as follows: 1g of nano-silicon dioxide is dispersed in 150ml of anhydrous ethanol, and then 1.5g of N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane is added to the mixed solution; the nano-silicon dioxide is subjected to amino modification by magnetic stirring at room temperature for 1.5h, so as to prepare a homemade nano-silicon dioxide solution; then, 1g of epoxy resin is dissolved in 99ml of anhydrous acetone at room temperature to prepare a solution, and after the epoxy resin is completely dissolved, 5g of dry nano-lignin is added to the solution, The reaction was continued for 3 hours while maintaining magnetic stirring at room temperature, and then the nano-lignin was purified by high-speed centrifugation. The purified nano-lignin was rinsed with acetone for more than 3 times and then dried with nitrogen. The epoxide-resinized nano-lignin was then immersed in a homemade nano-silica solution. After maintaining for 1.5 hours, the modified nano-lignin was purified by centrifugation and the product was rinsed with ethanol. 100 ml of ethanol was then added to the modified nano-lignin, and then the product was placed under an ultrasonic crusher for 5 minutes to be evenly dispersed, and finally dried with nitrogen to prepare the homemade nano-silica modified lignin.

[0034] In a specific implementation, the nano-lignin has an average particle size of 310 to 1000 nm, a hydroxyl content of 18 to 20 mmol / g, and a weight average molecular weight of 2124 to 3216 g / mol;

[0035] Modified nano-calcium carbonate: Nano-calcium carbonate was prepared by emulsion method, 5.55g CaCl2 and 5.3g Na2CO3 were weighed and placed in a 1L beaker, and 500mL deionized water was added to prepare a 0.1mol / L solution; the beaker containing the solution was placed in a constant temperature water bath and preheated to 40°C, the two solutions were quickly mixed under mechanical stirring conditions, and then aged for 5min under ultrasonic conditions; finally, the precipitate was filtered, washed, and dried to prepare nano-calcium carbonate; 5g of nano-calcium carbonate was weighed, diluted with 55ml of distilled water; and ultrasonically dispersed for 1h, then transferred to a three-necked flask, 0.5g of phenylalanine was added, and ultrasonically dispersed for 1h; placed in a constant temperature water bath, heated to 70°C, stirred at a rate of 1200rad / min, and reacted for 2h. After the reaction was completed, the product was filtered, washed, and vacuum dried to prepare modified nano-calcium carbonate.

[0036] During the specific implementation process, although phenylalanine is neutral and is not easy to react with the positively charged calcium ions of alkaline nano-calcium carbonate, phenylalanine can also be surface-grafted on the surface of nano-calcium carbonate under the present preparation conditions. The possible reason is that the carboxyl group in the amino acid can also chemically bond with the calcium ions on the surface of nano-calcium carbonate to synthesize calcium carboxylate.

[0037] A preparation method of a high-toughness biodegradable material for blown film molding: polyethylene, polybutylene adipate terephthalate, polylactic acid, self-made nano-silicon dioxide modified lignin, modified nano-calcium carbonate, plasticizer, compatibilizer, lubricant, carbon black and antioxidant are weighed in proportion; the various ingredients are mixed evenly and then the mixture is vacuum dried; after drying, the mixture is sent to a heating system for plasticization, and the plasticization temperature is set to 200-210 degrees Celsius; the plasticized mixture is subjected to secondary sol molding by a booster screw to completely fuse the mixture together; then the fusion is subjected to high-pressure multi-hole extrusion wire drawing molding, and the extrusion pressure is 3-4Mpa; the extruded fusion is qualitatively processed by a multi-stage cooling system, and then cut into particles by high speed, and finally dried for standby use, so as to prepare a high-toughness biodegradable material for blown film molding.

[0038] Example 2

[0039] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 52 parts of polyethylene, 10 parts of polybutylene adipate terephthalate, 7 parts of polylactic acid, 5 parts of homemade nano-silicon dioxide modified lignin, 4 parts of modified nano-calcium carbonate, 1.2 parts of plasticizer, 3.3 parts of compatibilizer, 0.3 parts of lubricant, 0.5 parts of carbon black, and 0.3 parts of antioxidant;

[0040] The lubricant is pentaerythritol stearate;

[0041] The antioxidant is a mixture of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate and didodecyl thiodipropionate;

[0042] Among them, in Example 2, the preparation method of the homemade nano-silicon dioxide modified lignin, the preparation method of the modified nano-calcium carbonate, and the preparation method of the high-toughness biodegradable material for blown film molding are all consistent with Example 1.

[0043] Example 3

[0044] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 6 parts of homemade nano-silicon dioxide modified lignin, 5 parts of modified nano-calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0045] The lubricant is tripolyglycerol distearate;

[0046] The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate;

[0047] Among them, in Example 3, the preparation method of the homemade nano-silicon dioxide modified lignin, the preparation method of the modified nano-calcium carbonate, and the preparation method of the high-toughness biodegradable material for blown film molding are all consistent with Example 1.

[0048] Example 4

[0049] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 56 parts of polyethylene, 14 parts of polybutylene adipate terephthalate, 10 parts of polylactic acid, 7 parts of homemade nano-silicon dioxide modified lignin, 6 parts of modified nano-calcium carbonate, 1.6 parts of plasticizer, 4 parts of compatibilizer, 0.7 parts of lubricant, 1 part of carbon black, and 0.6 parts of antioxidant;

[0050] The lubricant is tripolyglycerol distearate;

[0051] The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate;

[0052] Among them, in Example 4, the preparation method of the homemade nano-silicon dioxide modified lignin, the preparation method of the modified nano-calcium carbonate, and the preparation method of the high-toughness biodegradable material for blown film molding are all consistent with Example 1.

[0053] Example 5

[0054] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 58 parts of polyethylene, 15 parts of polybutylene adipate terephthalate, 11 parts of polylactic acid, 8 parts of homemade nano-silicon dioxide modified lignin, 7 parts of modified nano-calcium carbonate, 1.8 parts of plasticizer, 4.5 parts of compatibilizer, 0.9 parts of lubricant, 1.2 parts of carbon black, and 0.7 parts of antioxidant;

[0055] The lubricant is tripolyglycerol monostearate;

[0056] The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate or a mixture of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate and didodecyl thiodipropionate;

[0057] Among them, in Example 5, the preparation method of the homemade nano-silicon dioxide modified lignin, the preparation method of the modified nano-calcium carbonate, and the preparation method of the high-toughness biodegradable material for blown film molding are all consistent with Example 1.

[0058] Example 6

[0059] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 60 parts of polyethylene, 16 parts of polybutylene adipate terephthalate, 12 parts of polylactic acid, 9 parts of homemade nano-silicon dioxide modified lignin, 8 parts of modified nano-calcium carbonate, 2 parts of plasticizer, 5 parts of compatibilizer, 1 part of lubricant, 1.5 parts of carbon black, and 0.8 parts of antioxidant;

[0060] The lubricant is pentaerythritol stearate;

[0061] The antioxidant is a mixture of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate and didodecyl thiodipropionate;

[0062] Among them, in Example 6, the preparation method of the homemade nano-silicon dioxide modified lignin, the preparation method of the modified nano-calcium carbonate, and the preparation method of the high-toughness biodegradable material for blown film molding are all consistent with Example 1.

[0063] Comparative Example 1

[0064] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 1 part of nano silicon dioxide, 5 parts of lignin, 5 parts of modified nano calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0065] This comparative example 1 is based on Example 3, except that 6 parts of homemade nano-silicon dioxide modified lignin are directly replaced by 1 part of nano-silicon dioxide and 5 parts of lignin. Except for the above-mentioned different formulas, the preparation method of modified nano-calcium carbonate and the preparation method of high-toughness biodegradable material for blown film molding are consistent with Example 3.

[0066] Comparative Example 2

[0067] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 1 part of nano silicon dioxide, 5 parts of lignin, 5 parts of nano calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0068] This comparative example 2 is based on Example 3, except that 6 parts of homemade nano-silicon dioxide modified lignin are directly replaced by 1 part of nano-silicon dioxide and 5 parts of lignin, and the modified nano-calcium carbonate is replaced by nano-calcium carbonate without any modification; except for the above-mentioned different formulas, the preparation method of high-toughness biodegradable material for blown film molding is the same as that of Example 3.

[0069] Comparative Example 3

[0070] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 1 part of nano silicon dioxide, 5 parts of lignin, 5 parts of nano calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0071] This comparative example 3 is based on Example 3, except that the modified nano-calcium carbonate is replaced by nano-calcium carbonate without any modification; except for the above-mentioned different formulas, the preparation method of the homemade nano-silicon dioxide modified lignin and the preparation method of the high-toughness biodegradable material for blown film molding are consistent with Example 3.

[0072] Comparative Example 4

[0073] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 6 parts of homemade nano-silicon dioxide modified lignin, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0074] This comparative example 4 is based on Example 3, except that the addition of nano calcium carbonate is omitted; except for the above-mentioned different formulas, the preparation method of the homemade nano silicon dioxide modified lignin and the preparation method of the high-toughness biodegradable material for blown film molding are consistent with Example 3.

[0075] Comparative Example 5

[0076] A high-toughness biodegradable material for blown film molding, comprising the following components by weight: 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 5 parts of modified nano calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant;

[0077] This comparative example 5 is based on Example 3, except that the addition of homemade nano-silicon dioxide modified lignin is omitted; except for the above-mentioned different formulas, the preparation method of modified nano-calcium carbonate and the preparation method of high-toughness biodegradable material for blown film molding are consistent with Example 3.

[0078] Test example

[0079] The biodegradable materials for high-toughness blown film molding prepared in the above Examples 1-6 and Comparative Examples 1-5 were subjected to intelligent film blowing and film molding, and the prepared films were finally subjected to the following performance tests;

[0080] Refer to GB / T 1040.3-2006 "Determination of tensile properties of plastics" to test the tensile strength and elongation at break of the film. During the test, the gauge length is 100 mm and the tensile speed is 500 mm / min.

[0081] Refer to GB / T 16578.1-2008 "Determination of tear resistance of plastic films and sheets" to test the tear strength of the film;

[0082] Refer to GB / T 9639.1-2008 "Test method for impact resistance of plastic film and sheeting - free falling dart method" to test the dart impact strength of the film;

[0083] The data of the above test results are shown in Table 1.

[0084] Table 1

[0085]

[0086] Comprehensive performance analysis: Examples 1-6 of the present application all have excellent tensile strength, elongation at break, tear strength, and dart impact strength. The above indicators can characterize that the material prepared by the present application can undergo a large deformation during the stress process, and is not easy to break or damage, and can effectively absorb energy during impact or rapid loading, and has excellent durability and reliability.

[0087] The lignin used in Comparative Example 1 was not modified in any way. Instead, 6 parts of the homemade nano-silica-modified lignin were directly replaced with 1 part of nano-silica and 5 parts of lignin. The performance of the lignin was significantly weaker than that of Examples 1-6. The possible reason is that the homemade nano-silica-modified lignin introduced in Examples 1-6 used N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane amino-modified nano-silica, which can not only form hydrogen bonds with functional groups such as hydroxyl groups in lignin, but also form chemical bonds with the matrix in the degradation material, significantly increasing the degradation rate. Strong interface bonding force improves interface compatibility; makes stress transfer between the matrix and the homemade nano-silica modified lignin easier, and is not prone to fatigue limits caused by defects during stretching; and the lignin modified by homemade nano-silica can also adjust the particle polarity of nano-lignin, giving it a more hydrophobic property. With its volume effect and quantum tunneling effect, it can produce a penetration effect, penetrate deep into the π bond attachment of the polymer compound, overlap with its electron cloud, form a spatial network structure, and greatly improve the toughness of the material.

[0088] The nano-calcium carbonate used in Comparative Example 3 has not been modified in any way, and its performance is also significantly weaker than that of Examples 1-6. The possible reasons are: the carboxyl groups of the phenylalanine-modified nano-calcium carbonate introduced in Examples 1-6 can be chemically bonded with the calcium ions in the nano-calcium carbonate; and the steric hindrance of phenylalanine itself is also conducive to improving the dispersion of the nano-calcium carbonate. The nano-calcium carbonate itself exhibits a toughening effect of rigid particles. After modification, the compatibility between the nano-calcium carbonate and the substrate is further improved, the combination is closer, and a certain strength of interfacial adhesion is generated between the inorganic particles, which can weaken the force between the polymer chains, making the movement of the polymer chains easier, and the elongation at break is improved, thereby having high toughness.

[0089] In Comparative Example 2, neither lignin nor nano-calcium carbonate has been modified in any way. They are added as ordinary fillers as in the prior art. Their performance in terms of toughness is significantly different from that of the present application, because the existing nano-lignin is prone to agglomeration in the base material, and the interfaces are more incompatible. When subjected to stress, the stress between the base and the nano-lignin cannot be effectively transmitted, thus resulting in a significant deterioration in toughness.

[0090] Comparative Examples 4 and 5 selected one of the homemade nano-silicon dioxide modified lignin and modified nano-calcium carbonate for addition, but could not obtain the beneficial effects of Examples 1-6 of the present application, indicating that the material for blown film molding of the present application has super high toughness only through the composite use of homemade nano-silicon dioxide modified lignin and modified nano-calcium carbonate.

[0091] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-toughness biodegradable material for film blowing, characterized in that: The composition is as follows by weight: 50-60 parts of polyethylene, 8-16 parts of polybutylene adipate terephthalate, 6-12 parts of polylactic acid, 4-9 parts of self-made nano-silicon dioxide modified lignin, 3-8 parts of modified nano-calcium carbonate, 1-2 parts of plasticizer, 3-5 parts of compatibilizer, 0.2-1 parts of lubricant, 0.3-1.5 parts of carbon black, and 0.2-0.8 parts of antioxidant; the preparation method of the self-made nano-silicon dioxide modified lignin is as follows: nano-silicon dioxide is dispersed in anhydrous ethanol, and then N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane is added to the mixed solution; the nano-silicon dioxide is modified by magnetic stirring at room temperature for 1.5 hours; then, epoxy resin is dissolved in anhydrous acetone at room temperature and prepared The invention discloses a method for preparing a nano-lignin-modified lignin-based product. The method comprises the steps of: forming a solution, adding dry nano-lignin to the solution after the epoxy resin is completely dissolved, maintaining magnetic stirring at room temperature, and continuing the reaction for 3 hours. The nano-lignin is then purified by high-speed centrifugation. The purified nano-lignin is rinsed with acetone for more than 3 times and then dried with nitrogen. The nano-lignin-modified with epoxy resin is then immersed in a homemade nano-silicon dioxide solution. After maintaining the solution for 1.5 hours, the modified nano-lignin is purified by centrifugation and the product is rinsed with ethanol. The modified nano-lignin is then added with ethanol, and then placed under an ultrasonic crusher for 5 minutes to disperse it evenly. Finally, the nano-lignin is dried with nitrogen to prepare the homemade nano-silicon dioxide-modified lignin. The modified nano-calcium carbonate is phenylalanine-modified nano-calcium carbonate.

2. A high-toughness biodegradable material for blown film molding according to claim 1, characterized in that: The composition is as follows by weight, including 54 parts of polyethylene, 12 parts of polybutylene adipate terephthalate, 8 parts of polylactic acid, 6 parts of homemade nano-silicon dioxide modified lignin, 5 parts of modified nano-calcium carbonate, 1.4 parts of plasticizer, 3.5 parts of compatibilizer, 0.5 parts of lubricant, 0.8 parts of carbon black, and 0.5 parts of antioxidant.

3. The high-toughness biodegradable material for blown film molding according to claim 1, characterized in that: The plasticizer is acetyl tributyl citrate.

4. The high-toughness biodegradable material for blown film molding according to claim 1, characterized in that: The compatibilizer is maleic anhydride.

5. The high-toughness biodegradable material for blown film molding according to claim 1, characterized in that: The lubricant is one or more of triglycerol monostearate, triglycerol distearate, and pentaerythritol stearate.

6. The high-toughness biodegradable material for blown film molding according to claim 1, characterized in that: The antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate or a combination of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate and didodecyl thiodipropionate.

7. A high-toughness biodegradable material for blown film molding according to any one of claims 1 to 6, characterized in that: The preparation method of the modified nano calcium carbonate is as follows: taking CaCl2 and Na2CO3 respectively and placing them in a beaker, adding deionized water to prepare a solution; placing the beaker containing the solution in a constant temperature water bath and preheating to 40°C, rapidly mixing the two solutions under mechanical stirring conditions, and then aging them under ultrasonic conditions for 5 minutes; finally, filtering, washing, and drying the precipitate to prepare the nano calcium carbonate; taking the nano calcium carbonate, diluting it with distilled water, and ultrasonically dispersing it for 1 hour, then transferring it to a three-necked flask, adding phenylalanine, and ultrasonically dispersing it for 1 hour; placing it in a constant temperature water bath, heating it to 70°C, stirring at a rate of 1200rad / min, reacting for 2 hours, and after the reaction is completed, filtering, washing, and vacuum drying the obtained product to prepare the modified nano calcium carbonate.

8. A high-toughness biodegradable material for blown film molding according to any one of claims 1 to 6, characterized in that: The high-toughness biodegradable material for blown film molding and the preparation method thereof are as follows: polyethylene, polybutylene adipate terephthalate, polylactic acid, homemade nano-silicon dioxide modified lignin, modified nano-calcium carbonate, plasticizer, compatibilizer, lubricant, carbon black, and antioxidant are weighed; and the various ingredients are mixed evenly, and the mixture is vacuum dried; after the drying is completed, the mixture is sent to a heating system for plasticization; the plasticized mixture is subjected to secondary sol molding by a booster screw to completely fuse the mixture together; then the fusion is subjected to high-pressure multi-porous extrusion wire drawing molding, and the extrusion pressure is 3-4Mpa; the extruded fusion is qualitatively processed by a multi-stage cooling system, and then cut into particles by high speed, and finally dried for standby use, so as to prepare a high-toughness biodegradable material for blown film molding.

9. A high-toughness biodegradable material for blown film molding as claimed in claim 8, characterized in that: In the preparation process of the high-toughness biodegradable material for blown film molding, the temperature of the plasticizing treatment is set to 200-210 degrees Celsius.

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