Preparation method of biodegradable plastic

Abstract

The invention provides a preparation method of biodegradable plastic, and relates to the technical field of plastic preparation. The preparation method of the biodegradable plastic specifically comprises the following steps: step 1, taking algae as a biological matrix raw material of the biodegradable plastic, and washing, slicing and grinding the biomass-based raw material; and step 2, preparing the Zein protein composite material: taking Zein protein as a main body, and adding a plasticizer, a reinforcing agent, an additive, fibers and a nano material to prepare the Zein protein composite material. The softness and elasticity of the material can be provided by taking algae as a carrier, the mechanical strength and stability of the material can be improved by taking zein as a main body of the composite material, the production cost and the waste of non-renewable resources can be reduced by virtue of the renewability and universality of the raw materials, and the recycling of redundant materials in the preparation process is realized; generation of waste is reduced, and environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of plastic preparation, in particular to a method for preparing biodegradable plastic. Background Art

[0002] Plastic is one of the most commonly used materials in industry and life. Plastic has been widely developed in many fields due to its advantages such as light weight, high strength, stable chemical properties and low cost. The rapid development of the plastic industry has brought great convenience to people's production and life, but the "white pollution" problem caused by plastic waste is also becoming increasingly serious. The environmental pollution caused by difficult-to-degrade plastics has attracted more and more attention and attention from countries around the world. The use of biodegradable plastics is a fundamental way to solve plastic pollution. However, there is no proper disposal method for used plastics, and plastic waste brings serious pollution to the natural environment. Most non-degradable plastics are developed and produced from low-density polyethylene and linear low-density polyethylene, followed by high-density polyethylene, polypropylene, polystyrene and polyvinyl chloride.

[0003] The existing patent (CN103694713B) "A method for preparing a biodegradable protein plastic. The present invention discloses a method for preparing a biodegradable protein plastic, which comprises mixing soy protein isolate and fish meal into a mixed protein, mixing the mixed protein with triethyl citrate for 20 to 40 minutes, adding formamide and mixing for 40 to 50 minutes, placing the obtained material in a mold for hot pressing to obtain a biodegradable protein plastic. The raw materials used in the present invention are soy protein isolate and fish meal, which have a wide range of sources. The materials used are all biodegradable materials. The protein plastic has good biodegradability and is an environmentally friendly material, which avoids causing environmental pollution." It can be seen that biodegradable plastics have been produced and applied, but among biodegradable plastics, the mechanical properties and heat resistance of the degradable plastics prepared from natural polymer substances such as protein and fish meal are relatively low, resulting in great limitations on the scope of application; at the same time, the patent CN101696284A discloses a degradable plastic, which has a high cost of raw materials and is not industrially produced. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for preparing a biodegradable plastic, which solves the problems of low mechanical properties and heat resistance of the biodegradable plastic, high cost of plastic raw materials, and non-utilization of industrial production.

[0005] (II) Technical solution To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing biodegradable plastics, specifically comprising the following steps: Step 1. Using algae as the biomass-based raw material for biodegradable plastic, the biomass-based raw material is washed, sliced, and ground; Step 2. Prepare Zein protein composite materials, using Zein protein as the main component, adding plasticizers, reinforcing agents, additives, fibers, and nanomaterials to prepare Zein protein composite materials; Step 3. After the biomass-based raw material is sliced ​​and ground in step 1, moisture is removed, and the dried biomass-based raw material is converted into an ester compound by acid hydrolysis and alcoholization, and a small molecule compound is generated by cracking and the compound is collected; Step 4. Mixing preparation Add the small molecule compound polymer collected in step 3 to an appropriate amount of water, stir evenly to make a matrix paste; in another container, add the Zein protein composite material and filler obtained in step 2 to an appropriate amount of solvent, stir and mix until evenly dispersed; slowly add the suspension of the Zein protein composite material evenly mixed with the filler to the matrix paste, stir and mix continuously to ensure that the materials are fully and evenly mixed, gradually add antioxidants and UV stabilizers to the mixture, and stir well, finally, add glycerin as a plasticizer and stir and mix well again, pour the final mixture into a mold, undergo appropriate hot pressing and molding process, dry and solidify, cool and perform surface treatment to obtain the desired biodegradable plastic.

[0006] Preferably, the specific preparation method of the Zein protein composite material in step 2 is: The Zein protein is dissolved in a suitable solvent to obtain a Zein protein solution, a plasticizer is added to the Zein protein solution, and after an appropriate amount of stirring is mixed evenly, a reinforcing agent is added to the solution to ensure that the reinforcing agent is evenly dispersed in the solution, and then the required additives are added and stirred to mix evenly, and the fiber is gradually added to the solution and continued to be stirred to make it evenly dispersed. Finally, nanomaterials are added to ensure that the nanomaterials are evenly dispersed in the solution, and continued to be stirred and mixed. The final mixture is poured into a mold and dried and cured through an extrusion molding process.

[0007] Preferably, the plasticizer used in the specific preparation method of the Zein protein composite material is one of glycerol and butanol, the reinforcing agent is one of cellulose fiber or polymer fiber, the additive is one or more of plasticizer and antioxidant, the fiber is resin fiber, and the nanomaterial is one of nano oxide, wherein the Zein protein is zein.

[0008] Preferably, the moisture removal treatment of the biomass-based raw material in step 3 adopts a microwave heating method to remove moisture from the biomass-based raw material.

[0009] Preferably, the acid hydrolysis treatment in step 3 is to use an acidic solution to decompose the biomass-based raw material into oligomers, wherein the acidic solution can be one of hydrochloric acid, sulfuric acid, and formic acid, and the alcoholization treatment is based on the alcohol mixing treatment in which the decomposed oligomer compounds are mixed with one of ethanol and propanol solutions after the acid hydrolysis treatment and a catalyst is added to react.

[0010] Preferably, the specific operation steps of the cleavage in step 3 are: After the ester compound product treated by acid hydrolysis and alcoholization reaction is washed and dried, the ester compound product is cracked into small molecular compounds using a catalyst and high temperature.

[0011] Preferably, the filler used in step 4 is cellulose fiber.

[0012] Preferably, in step 2, Zein protein: plasticizer = 20:20 (wt%); Zein protein: enhancer: additive = 20:10:20 (wt%); Zein protein:fiber:nanomaterial=20:10:10 (wt%).

[0013] (III) Beneficial effects The present invention provides a method for preparing biodegradable plastics, which has the following beneficial effects: Biodegradable plastic materials with excellent physical properties and biocompatibility are obtained by using traditional algae as a carrier and adding Zeinprotein composite materials prepared with zein as the main body and various auxiliary materials. The algae as a carrier can provide the material with softness and elasticity, while the composite material with zein as the main body can improve the mechanical strength, stability and high heat resistance of the material, and also has good biocompatibility and degradability. The renewability and universality of algae can reduce production costs and waste of non-renewable resources. At the same time, the main raw materials prepared by algae and composite materials can realize the recycling of excess materials in the preparation process, reduce the generation of waste, and reduce environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The embodiment of the present invention provides a biodegradable plastic, including 30 parts of algae biomatrix raw materials, 45 parts of Zein protein composite materials which are mainly Zein protein and mixed with plasticizers, reinforcing agents, additives, fibers and nanomaterials, 10 parts of fillers, and 15 parts of reinforcing agents, 10 parts of additives, 6 parts of fibers and 20 parts of nanomaterials.

[0017] like Figure 1 As shown, a method for preparing a biodegradable plastic specifically comprises the following steps: Step 1. Using algae as the biomass-based raw material for biodegradable plastic, the biomass-based raw material is washed, sliced, and ground; Place the freshly harvested algae in clean water and rinse them repeatedly to remove the mud, sand, impurities, etc. attached to the surface of the algae; slice the cleaned algae to reduce its size for subsequent grinding and extraction. The slicing method can select appropriate tools according to the type and size of the algae, such as blades, slicers, etc.; grind the sliced ​​algae to obtain fine powdered biomass raw materials. The grinding method can select a ball mill, a crusher, etc., and select the appropriate grinding degree according to needs.

[0018] That is, biological matrix raw material = algae → cleaning → washing algae → slicing → slicing algae → grinding → algae powder; Step 2. Prepare Zein protein composite materials, using Zein protein as the main body, adding plasticizers, reinforcing agents, additives, fibers, and nanomaterials to prepare Zein protein composite materials; wherein the plasticizer used is one of glycerol and butanol, the reinforcing agent is one of cellulose fiber or polymer fiber, the additive is one or more of plasticizer and antioxidant, the fiber is resin fiber, and the nanomaterial is one of nano oxides, wherein the Zein protein is zein; Zein protein: plasticizer = 20:20 (wt%); Zein protein: enhancer: additive = 20:10:20 (wt%); Zein protein: fiber: nanomaterial = 20:10:10 (wt%) Dissolve zein in an ethanol solvent with a concentration of 70%-90%, stir at a temperature of 25-50°C and a speed of 50-100 rpm for 2-4 hours until completely dissolved to obtain a Zein protein solution with a concentration of 10%-20%; add a glycerol plasticizer to the Zein protein solution, the ratio of the glycerol plasticizer to the Zein protein solution is 5%-20%, stir at a temperature of 25-50°C and a speed of 100-200 rpm for 1-2 hours to mix evenly, add a polymer fiber reinforcement to the solution to ensure that the reinforcement is evenly dispersed in the solution, the ratio of the polymer fiber reinforcement to the Zein protein solution is 5%-30%, stir at a temperature of 25-50°C and a speed of 100-200 rpm for 1-2 hours to mix evenly; Then, the required plasticizer and antioxidant are added as additives and stirred to mix evenly, and the resin fiber is gradually added to the solution and stirred to make it evenly dispersed, wherein the proportion of the plasticizer and antioxidant to the Zein protein solution is 5%-15% and 0.5%-2%, respectively, and the proportion of the resin fiber is 5%-30%. The temperature is 25-50°C, the stirring rate is 100-200rpm, and the stirring is carried out for 1-2h to mix evenly; Finally, add nano-oxide material and ensure that the nano-oxide material is evenly dispersed in the solution, and continue to stir and mix, with a ratio of 1%-5% of nano-oxide material relative to the Zein protein solution, at a temperature of 25-50°C and a stirring rate of 100-200rpm, after stirring and mixing evenly for 1-2h, pour the final mixture into a mold, and dry and cure through an extrusion molding process; finally, the drying and curing are completed with a drying temperature of 50-80°C, a drying time of 12-24h, a curing temperature of 80-120°C, and a curing time of 2-4h.

[0019] Step 3. After the biomass-based raw material is sliced ​​and ground in step 1, moisture is removed, and the dried biomass-based raw material is converted into an ester compound by acid hydrolysis and alcoholization, and a small molecule compound is generated by cracking and the compound is collected; The moisture removal treatment of biomass-based raw materials adopts a microwave heating method to remove moisture from the biomass-based raw materials, with a microwave frequency of 2.45GHz, a power of 500-1000w, and a temperature of 60-100℃ for 5-30 minutes to uniformly heat and remove moisture; The acid hydrolysis treatment is to use an acidic solution to decompose the biomass-based raw materials into oligomers, wherein the acidic solution can be one of hydrochloric acid, sulfuric acid, and formic acid. Here, hydrochloric acid is used for the acid hydrolysis treatment; that is, the pretreated raw materials are mixed with a hydrochloric acid solution, and reacted at a certain temperature and time. After the reaction is completed, the acidic solution is neutralized with a sodium hydroxide solution to terminate the reaction, and the neutralized product is washed with water to remove residual acid and salt, and the washed product is dried to the required moisture content; The alcoholization treatment is an alcohol mixing treatment based on mixing the decomposed oligomeric compound with one of ethanol and propanol solutions after the acid hydrolysis treatment and adding a catalyst for reaction. Here, ethanol is used for the mixing treatment; that is, the oligomeric compound after acid hydrolysis is mixed with an alcohol solution and a catalyst, and the catalyst is a sodium hydroxide catalyst for reaction and mixing, and the reaction is carried out at a certain temperature and time. After the reaction is completed, the alkaline solution is neutralized with a hydrochloric acid solution to terminate the reaction, and the neutralized product is washed with water to remove residual acid and salt, and the washed product is dried to a desired moisture content; After the acid hydrolysis and alcoholization reaction, the ester compound product is washed and dried, and then the ester compound product is cracked into small molecular compounds using a catalyst and high temperature; that is, the dried ester compound product is mixed with a catalyst and cracked under high temperature conditions. The cracking reaction temperature is 300-500°C, the catalyst is zeolite, and the gas products produced by the cracking reaction are collected and separated by condensation.

[0020] Step 4. Mixing preparation Add the small molecule compound polymer collected in step 3 to an appropriate amount of water, stir evenly, and prepare a matrix paste; in another container, add the Zein protein composite material and cellulose fiber filler obtained in step 2 to an appropriate amount of ethanol solvent, stir with a high-speed stirrer, and stir and mix at 1000-3000 rpm at room temperature until uniformly dispersed; slowly add the suspension of the Zein protein composite material mixed with the filler to the matrix paste, stir and mix continuously to ensure that the materials are fully and evenly mixed, gradually add antioxidants and UV stabilizers to the mixture, and stir well, and finally, add glycerin as a plasticizer and stir and mix well again; The final mixture is poured into the mold, and after an appropriate hot pressing process, the mold is placed in a hot pressing machine, and the temperature is 80-120°C and the pressure is 5-15MPa. After hot pressing, the hot pressing material is placed in a drying oven for drying and curing at a temperature of 40-60°C. After cooling to room temperature, the surface is treated to obtain the desired biodegradable plastic.

[0021] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a biodegradable plastic, characterized in that: The specific steps include: Step 1. Using algae as the biomass-based raw material for biodegradable plastic, the biomass-based raw material is washed, sliced, and ground; Step 2. Prepare Zein protein composite materials, using Zein protein as the main component, adding plasticizers, reinforcing agents, additives, fibers, and nanomaterials to prepare Zein protein composite materials; Step 3. After the biomass-based raw material is sliced ​​and ground in step 1, moisture is removed, and the dried biomass-based raw material is converted into an ester compound by acid hydrolysis and alcoholization, and a small molecule compound is generated by cracking and the compound is collected; Step 4. Mixing preparation Add the small molecule compound polymer collected in step 3 to an appropriate amount of water, stir evenly to make a matrix paste; in another container, add the Zein protein composite material and filler obtained in step 2 to an appropriate amount of solvent, stir and mix until evenly dispersed; slowly add the suspension of the Zein protein composite material evenly mixed with the filler to the matrix paste, stir and mix continuously to ensure that the materials are fully and evenly mixed, gradually add antioxidants and UV stabilizers to the mixture, and stir well, finally, add glycerin as a plasticizer and stir and mix well again, pour the final mixture into a mold, undergo appropriate hot pressing and molding process, dry and solidify, cool and perform surface treatment to obtain the desired biodegradable plastic.

2. The method for preparing a biodegradable plastic according to claim 1, characterized in that: The specific preparation method of the Zein protein composite material in step 2 is: The Zein protein is dissolved in a suitable solvent to obtain a Zein protein solution, a plasticizer is added to the Zein protein solution, and after an appropriate amount of stirring is mixed evenly, a reinforcing agent is added to the solution to ensure that the reinforcing agent is evenly dispersed in the solution, and then the required additives are added and stirred to mix evenly, and the fiber is gradually added to the solution and continued to be stirred to make it evenly dispersed. Finally, nanomaterials are added to ensure that the nanomaterials are evenly dispersed in the solution, and continued to be stirred and mixed. The final mixture is poured into a mold and dried and cured through an extrusion molding process.

3. The method for preparing a biodegradable plastic according to claim 2, characterized in that: The plasticizer used in the specific preparation method of the Zeinprotein composite material is one of glycerol and butanol, the reinforcing agent is one of cellulose fiber or polymer fiber, the additive is one or more of plasticizer and antioxidant, the fiber is resin fiber, and the nanomaterial is one of nano oxides, wherein the Zein protein is corn alcohol-soluble protein.

4. The method for preparing a biodegradable plastic according to claim 1, characterized in that: In the step 3, the moisture removal treatment for the biomass-based raw material adopts a microwave heating method to remove the moisture in the biomass-based raw material.

5. The method for preparing a biodegradable plastic according to claim 1, characterized in that: The acid hydrolysis treatment in step 3 is to decompose the biomass-based raw materials into oligomers using an acidic solution, wherein the acidic solution can be one of hydrochloric acid, sulfuric acid, and formic acid, and the alcoholization treatment is based on mixing the decomposed oligomer compounds with one of ethanol and propanol solutions after the acid hydrolysis treatment and adding a catalyst to react with alcohol mixing treatment.

6. The method for preparing a biodegradable plastic according to claim 1, characterized in that: The specific operation steps of the cracking in step 3 are: After the ester compound product treated by acid hydrolysis and alcoholization reaction is washed and dried, the ester compound product is cracked into small molecular compounds using a catalyst and high temperature.

7. The method for preparing a biodegradable plastic according to claim 1, characterized in that: The filler used in step 4 is cellulose fiber.

8. The method for preparing a biodegradable plastic according to claim 1, characterized in that: In the step 2, Zein protein: plasticizer = 20:20 (wt%); Zein protein: enhancer: additive = 20:10:20 (wt%); Zein protein:fiber:nanomaterial=20:10:10 (wt%).

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