Bamboo powder reinforced and replaced biodegradable plastic and preparation method thereof

Abstract

The invention discloses a bamboo powder reinforced and replaced biodegradable plastic and a preparation method thereof, and belongs to the technical field of biodegradable plastics. Comprising the following raw materials in parts by weight: 10-20 parts of modified bamboo powder, 45-55 parts of PBAT resin, 30-40 parts of polylactic acid, 3-5 parts of modified humic acid filler, 5-8 parts of epoxidized soybean oil, 0.3-0.5 part of an antioxidant, 0.3-0.6 part of a light stabilizer, 4-6 parts of a compatilizer and 0.3-0.5 part of an epoxy chain extender. According to the bamboo powder reinforced and replaced biodegradable plastic and the preparation method thereof, the modified bamboo powder and the humic acid filler are compounded with the PBAT, the polylactic acid and other raw materials, so that the cost is reduced and the environmental protection property is improved by utilizing the bamboo powder, the humic acid and other renewable resources, and the compatibility with a matrix is enhanced through modification; the antioxidant, the light stabilizer and the like are matched, so that the mechanical property is improved, and multiple advantages of low cost, high performance and degradability are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biodegradable plastics, in particular to a kind of bamboo powder reinforced alternative biodegradable plastics and preparation method thereof. BACKGROUND

[0002] With the increasingly serious global "white pollution" problem, and the urgent demand for green and environmentally friendly materials under the "double carbon" policy, biodegradable plastics gradually replace traditional petroleum-based plastics and become a research hotspot. Although the mainstream biodegradable plastics (such as polybutylene adipate terephthalate (PBAT), polylactic acid (PLA) and the like) can be naturally degraded, they have the following limitations:

[0003] PBAT has excellent toughness but low strength, PLA has high strength but is brittle, and pure components are difficult to meet the mechanical performance requirements in complex scenarios. Natural plant fibers (such as bamboo powder) are abundant in source, low in cost and biodegradable, and are often used as reinforcing fillers added to polymer matrix. However, the compatibility of bamboo powder and polymer matrix is poor, which easily leads to the decline of the performance of the composite material. At the same time, the effect of a single reinforcing filler is limited, which is difficult to meet the requirements of actual application on the comprehensive performance of the material. Therefore, it is urgent to prepare a composite plastic material with excellent mechanical performance, suitable cost and complete degradation by reasonable formulation design and modification process. SUMMARY

[0004] The purpose of the present application is to provide a kind of bamboo powder reinforced alternative biodegradable plastics and preparation method thereof. By modifying bamboo powder and humic acid filler and compounding with PBAT, polylactic acid and the like, it is prepared by optimizing process. It not only utilizes renewable resources such as bamboo powder and humic acid to reduce cost and improve environmental protection, but also improves the compatibility with the matrix by modification and reinforcement, and improves the mechanical properties and weather resistance by cooperating with antioxidants, light stabilizers and the like. At the same time, the processing parameters are optimized to ensure the processing stability, realizing the multiple advantages of low cost, high performance and biodegradability.

[0005] To achieve the above purpose, the present application provides a kind of bamboo powder reinforced alternative biodegradable plastics, by mass fraction, including the following raw materials: 10-20 parts of modified bamboo powder, 45-55 parts of PBAT resin, 30-40 parts of polylactic acid, 3-5 parts of modified humic acid filler, 5-8 parts of epoxy soybean oil, 0.3-0.5 parts of antioxidant, 0.3-0.6 parts of light stabilizer, 4-6 parts of compatibilizer and 0.3-0.5 parts of epoxy chain extender.

[0006] Preferably, the light stabilizer is a hindered amine stabilizer, and the antioxidant is a compound of hindered phenolic antioxidant and phosphite antioxidant, wherein the ratio of hindered phenolic antioxidant to phosphite antioxidant is 1:1.

[0007] The application also provides a preparation method of the bamboo powder reinforced and substituted biodegradable plastic, comprising the following steps:

[0008] S1, preparing modified bamboo powder;

[0009] S2, modifying humic acid after humic acid pretreatment to obtain modified humic acid filler;

[0010] S3, adding the dried PBAT resin, polylactic acid, epoxy soybean oil, antioxidant and light stabilizer into a high-speed mixer for premixing, then adding a compatilizer for continuous mixing, then adding the modified bamboo powder obtained in S1 and the modified humic acid filler obtained in S2 for mixing, and then adding the premixed material into a double-screw extruder for melt extrusion and granulation, and adding an epoxy chain extender in the compression section during the extrusion process;

[0011] S4, after the extrusion and granulation, injection molding is performed to obtain the biodegradable plastic.

[0012] Further, in S3, the water content of the PBAT resin, polylactic acid, epoxy soybean oil, antioxidant, light stabilizer, modified bamboo powder obtained in S1, modified humic acid filler obtained in S2, epoxy soybean oil, antioxidant, light stabilizer, epoxy soybean oil, antioxidant, light stabilizer, epoxy soybean oil, antioxidant, light stabilizer and epoxy soybean oil is less than or equal to 0.05%.

[0013] Preferably, the specific operation of S1 is as follows:

[0014] S11, mixing bamboo powder and alkali solution, filtering and drying after soaking to obtain primary modified bamboo powder;

[0015] S12, first washing the primary modified bamboo powder obtained in S11 to neutral, then mixing and stirring with an ethanol solution of silane coupling agent KH550, and filtering and drying to obtain modified bamboo powder.

[0016] Preferably, in S11, the mesh number of the bamboo powder is 600-800 mesh, the concentration of the alkali solution is 5-8 wt%, the solid-liquid ratio of the bamboo powder and the alkali solution is 1g of bamboo powder: 8-12mL of alkali solution, the soaking temperature is 20-30℃, the soaking time is 3-4h, the drying temperature is 60-80℃, and the drying time is 4-6h.

[0017] Preferably, in S12, the amount of the silane coupling agent KH550 is 2-3 wt% of the amount of the primary modified bamboo powder, the solid-liquid ratio of the silane coupling agent KH550 and the ethanol solution is 1g: 6-8mL, the stirring temperature is 70-80℃, the stirring time is 1-2h, the drying is vacuum drying, the temperature is 60-80℃, the drying time is 4-5h, and the water content of the modified bamboo powder is less than or equal to 0.5%.

[0018] Preferably, in S2, the pretreatment of humic acid is: washing humic acid with deionized water for 3-5 times, then soaking with 0.1 mol / L HCl for 30-40 min, washing with water to neutral, and vacuum drying at 60-80℃ for 3-4h to obtain pretreated humic acid.

[0019] Preferably, in S2, the modification of humic acid is organic modification, and the treatment method of organic modification of humic acid includes: dispersing pretreated humic acid in 90% ethanol, adding biological surfactant, stirring at 60-80℃ for 4-6h, washing with ethanol for 3-5 times after filtration, and then drying at 60-80℃ for 3-5h to obtain modified humic acid filler, the amount of biological surfactant is 8-12% of the mass of pretreated humic acid.

[0020] Further, the biological surfactant is one of rhamnose or sophorolipid.

[0021] Preferably, in S3, the rotation speed of the high-speed mixer for pre-mixing is 600-1200rpm, and the time is 3-5min, and the rotation speed of the twin-screw extruder is 60-90r / min, and the temperature is controlled in stages: 140-150℃ for the feeding section, 160-170℃ for the compression section, and 180-185℃ for the melting section.

[0022] Preferably, in S4, the injection molding temperature is 175-190℃, and the injection molding pressure is 60-90MPa.

[0023] Therefore, the biodegradable plastic reinforced by the above-mentioned bamboo powder and the preparation method thereof have the following beneficial effects:

[0024] (1) Bamboo powder and humic acid are used as fillers to reduce the dependence on petroleum-based raw materials and reduce carbon emissions; PBAT and PLA are both biodegradable polymers, and the combination of natural fillers makes the final product biodegradable, solving the white pollution problem from the source;

[0025] (2) Bamboo powder and humic acid are widely available and low in price, significantly reducing the cost of raw materials;

[0026] (3) Excellent mechanical properties: after modification, the surface impurities of bamboo powder are removed, and functional groups that can react with PLA and PBAT are introduced, which greatly improves the compatibility with the matrix, enhances the interfacial bonding force, and significantly improves the tensile strength of the biodegradable plastic.

[0027] The technical solutions of the present application will be further described in detail below through examples. DETAILED DESCRIPTION

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0029] In the present application, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in the art, which can be purchased through commercial channels.

[0030] Example 1

[0031] The present application provides a kind of bamboo powder reinforced alternative biodegradable plastics, by mass fraction, including: 15 parts of modified bamboo powder, 50 parts of PBAT resin, 35 parts of polylactic acid, 4 parts of modified humic acid filler, 6 parts of epoxy soybean oil, 0.15 parts of antioxidant 1010, 0.15 parts of antioxidant 168, 0.4 parts of light stabilizer, 5 parts of compatibilizer and 0.4 parts of epoxy chain extender.

[0032] The preparation method of the above-mentioned bamboo powder reinforced alternative biodegradable plastic comprises the following steps:

[0033] S1, preparing modified bamboo powder, the specific operation is:

[0034] S11, mix 800 mesh bamboo powder with 6wt% NaOH lye, soak for 4h at 25℃, then filter and dry at 80℃ for 4h to obtain primary modified bamboo powder;

[0035] S12, first wash the primary modified bamboo powder obtained in S11 to neutral, then mix with 2.5wt% silane coupling agent KH550 ethanol solution at 75℃, stir for 1.5h, filter and vacuum dry at 80℃ for 4h to obtain modified bamboo powder.

[0036] The lignin, hemicellulose and other impurities on the surface of bamboo powder are easily dissolved in lye, and are removed after soaking, exposing more hydroxyl groups (-OH) and increasing the surface roughness; after drying, the hydroxyl groups can be prevented from reabsorbing water, laying a foundation for subsequent coupling modification.

[0037] The alkoxy group (-OR) of KH550 hydrolyzes to form silicon hydroxyl group (-Si-OH) in ethanol solution, which undergoes condensation reaction with the hydroxyl group (-OH) on the surface of bamboo powder (forming -Si-O- bond), realizing chemical grafting; and the amino group (-NH2) at the other end of KH550 can interact with the ester group (-COO-) of PBAT and the carboxyl group (-COOH) of PLA (such as hydrogen bond or chemical reaction), thereby building a "molecular bridge" between bamboo powder and polymer matrix, greatly improving the compatibility.

[0038] S2, modifying humic acid after pretreatment to obtain modified humic acid filler;

[0039] The pretreatment of humic acid is as follows: washing the humic acid with deionized water for 3 times, then soaking in 0.1 mol / L HCl for 30 min, washing with water until neutral, and vacuum drying at 80℃ for 4h to obtain pretreated humic acid. The deionized water washing removes soluble impurities, the dilute hydrochloric acid soaking can dissolve metal ions in humic acid to improve purity; vacuum drying can avoid agglomeration.

[0040] The modification of humic acid is organic modification. The treatment method of humic acid organic modification includes: dispersing pretreated humic acid in 90% ethanol, adding biosurfactant, stirring at 80℃ for 4h, washing with ethanol for 5 times after filtration, and then drying at 80℃ for 3h to obtain modified humic acid filler. The amount of biosurfactant is 8% of the mass of pretreated humic acid.

[0041] The biosurfactant can be adsorbed on the surface of humic acid through hydrophobic interaction, reducing its hydrophilicity; at the same time, the lipophilic group of the surfactant can be compatible with the hydrophobic segment of PBAT and PLA, so that the modified humic acid filler is uniformly dispersed in the matrix, playing a "micro-enhancing" role, and synergistically improving the overall mechanical properties of the material with bamboo powder.

[0042] S3, the dried PBAT resin, polylactic acid, epoxy soybean oil, antioxidant, light stabilizer are added into a high-speed mixer and premixed at 1000 rpm for 3 min, then the compatibilizer is added and mixed for 2 min, after mixing, the modified bamboo powder obtained in S1 and the modified humic acid filler obtained in S2 are added and mixed for 5 min, then the premixed material is added into a twin-screw extruder for melt extrusion and granulation. The epoxy chain extender is added in the compression section during the extrusion process. The rotation speed of the twin-screw extruder is 80 r / min, and the temperature is 145℃ for the feeding section, 165℃ for the compression section, and 180℃ for the melting section.

[0043] PBAT and PLA form a complement, and after compounding, they can balance the rigidity and toughness of the material; epoxy soybean oil as a plasticizer, its molecules can insert between the molecular chains of PBAT and PLA, weaken the intermolecular force, reduce the glass transition temperature, and improve the flexibility and processing fluidity of the material.

[0044] The hindered phenolic antioxidant terminates the oxidation chain reaction by capturing free radicals, and the phosphite antioxidant inhibits the generation of free radicals by decomposing hydroperoxide (ROOH), so that the two can realize "synergistic antioxidant" by 1:1 compounding, prolonging the service life of the material; the light stabilizer can capture active free radicals excited by ultraviolet light, or react with carbonyl compounds to inhibit photooxidation, reducing the damage of light to molecular chains.

[0045] After the epoxy chain extender is added in the compression section of the twin-screw extruder, the epoxy groups can undergo ring-opening reaction with the carboxyl groups (-COOH) and hydroxyl groups (-OH) at the ends of the molecular chains of PBAT and PLA, extending the molecular chains and improving the melt viscosity and mechanical properties.

[0046] Batch mixing can achieve the initial dispersion of each component, avoid local agglomeration, and segmented temperature control can ensure uniform plasticization of the material.

[0047] S4, after extrusion granulation, injection molding at 180 DEG C, 75 MPa, to obtain biodegradable plastics.

[0048] Example 2

[0049] The difference between this embodiment and example 1 is that, by mass fraction, it includes: 10 parts of modified bamboo powder, 55 parts of PBAT resin, 30 parts of polylactic acid, 3 parts of modified humic acid filler, 5 parts of epoxy soybean oil, 0.15 parts of antioxidant 1010, 0.15 parts of antioxidant 168, 0.4 parts of light stabilizer, 4 parts of compatibilizer and 0.3 parts of epoxy chain extender, and the rest of the conditions are the same.

[0050] Example 3

[0051] The difference between this embodiment and example 1 is that, by mass fraction, it includes: 20 parts of modified bamboo powder, 45 parts of PBAT resin, 40 parts of polylactic acid, 5 parts of modified humic acid filler, 8 parts of epoxy soybean oil, 0.15 parts of antioxidant 1010, 0.15 parts of antioxidant 168, 0.4 parts of light stabilizer, 6 parts of compatibilizer and 0.5 parts of epoxy chain extender, and the rest of the conditions are the same.

[0052] Comparative Example 1

[0053] The difference between this comparative example and example 1 is that: no epoxy chain extender is added in comparative example 1, and the rest of the conditions are the same.

[0054] Comparative Example 2

[0055] The difference between this comparative example and example 1 is that: the epoxy chain extender in comparative example 2 is added in the premixing stage, and the rest of the conditions are the same.

[0056] Comparative Example 3

[0057] The difference between this comparative example and example 1 is that: there is no humic acid filler in comparative example 3, and the rest of the conditions are the same.

[0058] The tensile strength, 60d soil burial degradation rate and 90d soil burial degradation rate of the biodegradable plastics provided by examples 1-3 and comparative examples 1-3 are tested, and the test results are shown in table 1.

[0059] Table 1 Performance test results

[0060]

[0061] From table 1, it can be known that, compared with comparative example 1 and comparative example 1, the absence of epoxy chain extender makes the mechanical property decrease significantly, compared with comparative example 1 and comparative example 2, the addition of epoxy chain extender in premixing also affects the mechanical property of the material, and makes the tensile strength decrease, thereby affecting the toughness; compared with comparative example 1 and comparative example 3, it can be known that the addition of humic acid can improve the degradation rate.

[0062] The biodegradable plastics 60d prepared in example 1 and comparative example 3 were mixed with soil after degradation, and radish seedlings were planted (30d period), and the fresh weight of the plants and the increase of soil organic matter and humic acid residue were detected, and the results are shown in table 2.

[0063] Table 2 test results

[0064]

[0065] From table 2, it can be known that, by adding humic acid, the organic matter in the soil after degradation of the biodegradable plastics can be significantly improved, and the growth of the plants is promoted, the residual amount of humic acid is ≤5%, which indicates that the humic acid is basically converted into absorbable nutrients, and the growth of the plants is promoted.

[0066] Therefore, the biodegradable plastics and the preparation method thereof using the above-mentioned bamboo powder reinforced alternative, by modifying the bamboo powder and humic acid filler and compounding with PBAT, polylactic acid and other raw materials, and through the optimized process, the cost is reduced and the environmental protection is improved by using renewable resources such as bamboo powder and humic acid, the compatibility with the matrix is enhanced by modification, the mechanical properties and weather resistance are improved by cooperating with antioxidants and light stabilizers, and the processing stability is ensured by optimizing the processing parameters, realizing the multiple advantages of low cost, high performance and biodegradability.

[0067] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A bamboo powder reinforced alternative biodegradable plastic, characterized by: The raw materials include, by mass: 10-20 parts of modified bamboo powder, 45-55 parts of PBAT resin, 30-40 parts of polylactic acid, 3-5 parts of modified humic acid filler, 5-8 parts of epoxy soybean oil, 0.3-0.5 parts of antioxidant, 0.3-0.6 parts of light stabilizer, 4-6 parts of compatibilizer and 0.3-0.5 parts of epoxy chain extender.

2. The bamboo powder reinforced alternative biodegradable plastic according to claim 1, characterized in that: The light stabilizer is a hindered amine stabilizer, and the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant, wherein the ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:

1.

3. The method for preparing a bamboo powder-reinforced alternative biodegradable plastic according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, preparing modified bamboo powder; S2, modifying the humic acid after pretreatment to obtain a modified humic acid filler; S3, adding the dried PBAT resin, polylactic acid, epoxy soybean oil, antioxidant, and light stabilizer to a high-speed mixer for premixing, then adding a compatibilizer and continuing to mix, and after mixing, adding the modified bamboo powder obtained in S1 and the modified humic acid filler obtained in S2 and mixing, and then adding the premix to a twin-screw extruder for melt extrusion and granulation, and adding an epoxy chain extender in the compression section during the extrusion process; S4, extrusion granulation followed by injection molding to obtain biodegradable plastics.

4. The method for preparing a bamboo powder-reinforced alternative biodegradable plastic according to claim 3, characterized in that: The specific operations of S1 are: S11, mixing bamboo powder with alkali solution, soaking, filtering and drying to obtain primary modified bamboo powder; S12. Wash the primary modified bamboo powder obtained in S11 with water until it is neutral, then mix and stir with an ethanol solution of a silane coupling agent KH550, filter and dry to obtain the modified bamboo powder.

5. The method for preparing a bamboo powder reinforced alternative biodegradable plastic according to claim 4, characterized in that: In S11, the mesh size of the bamboo powder is 600-800 mesh, the concentration of the alkali solution is 5-8wt%, the solid-liquid ratio of bamboo powder to alkali solution is: 1g bamboo powder: 8-12mL alkali solution, the soaking temperature is 20-30°C, the soaking time is 3-4h, the drying temperature is 60-80°C, and the drying time is 4-6h.

6. The method for preparing a bamboo powder-reinforced alternative biodegradable plastic according to claim 4, characterized in that: In S12, the amount of silane coupling agent KH550 is 2-3wt% of the amount of the modified bamboo powder, the solid-liquid ratio of the silane coupling agent KH550 to the ethanol solution is 1g:6-8mL, the stirring temperature is 70-80°C, the stirring time is 1-2h, the drying is vacuum drying at a temperature of 60-80°C, the drying time is 4-5h, and the moisture content of the modified bamboo powder is ≤0.5%.

7. The method for preparing a bamboo powder reinforced alternative biodegradable plastic according to claim 3, characterized in that: In S2, the humic acid is pretreated by washing the humic acid with deionized water for 3-5 times, then soaking it with 0.1 mol / L HCl for 30-40 minutes, then washing it with water until it is neutral, and vacuum drying it at 60-80° C. for 3-4 hours to obtain pretreated humic acid.

8. The method for preparing a bamboo powder reinforced alternative biodegradable plastic according to claim 7, characterized in that: In S2, the modification of humic acid is organic modification. The treatment method of organic modification of humic acid includes: dispersing the pretreated humic acid in 90% ethanol, adding a biosurfactant, stirring at 60-80°C for 4-6 hours, filtering, washing with ethanol 3-5 times, and then drying at 60-80°C for 3-5 hours to obtain a modified humic acid filler. The amount of the biosurfactant is 8-12% of the mass of the pretreated humic acid.

9. The method for preparing a bamboo powder reinforced alternative biodegradable plastic according to claim 3, characterized in that: In S3, the speed of the high-speed mixer pre-mixing is 600-1200 rpm, the time is 3-5 minutes, the speed of the twin-screw extruder is 60-90 r / min, and the temperature is controlled in stages: 140-150°C in the feeding section, 160-170°C in the compression section, and 180-185°C in the melting section.

10. The method for preparing a bamboo powder reinforced alternative biodegradable plastic according to claim 3, characterized in that: In S4, the injection molding temperature is 175-190° C., and the injection molding pressure is 60-90 MPa.

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