Foaming packaging material prepared from cold storage rotten vegetable leaves and tapioca flour and preparation method of foaming packaging material

Abstract

The invention discloses a foaming packaging material prepared from cold storage rotten vegetable leaves and tapioca flour and a preparation method thereof.The foaming packaging material is prepared from, by weight, 20%-35% of vegetable fiber, 30%-40% of tapioca flour, 20%-35% of vegetable juice, 1%-2% of plasticizer, 2%-5% of nucleating agent, 0.5%-1% of release agent and the balance water. The preparation method comprises the following steps: (1) preparing raw materials according to a formula; (2) crushing the rotten vegetable leaves and pulping; (3) screening out stem residues from the residual vegetable pulp; (4) carrying out solid-liquid separation on the sieved sauce to separate out solid vegetable fibers and liquid vegetable juice; (5) adding a plasticizer; (6) taking tapioca flour, and putting the tapioca flour, the vegetable juice and the plasticizer into a mixing machine; (7) putting the solid vegetable fibers, a nucleating agent and a release agent into a mixer for mixing and stirring; (8) feeding the mixed and modified material into a screw extruder; and (9) quantitatively outputting the material into a mold of a press machine by the screw extruder, and demolding to obtain the foaming packaging material.

Description

Technical Field

[0001] This invention relates to the fields of environmental protection and polymer packaging materials, and in particular to foamed packaging materials made from cold storage waste vegetables and cassava flour, and their preparation methods. Background Technology

[0003] Currently, the most common method for processing vegetable waste is solid-liquid separation, with the solid portion fed to fish and the liquid portion discharged. The main technology for processing vegetable waste is anaerobic digestion power generation, but this technology generates large amounts of biogas residue and biogas slurry, which has become a bottleneck for treatment companies and results in high processing costs. Cold storage facilities require a large amount of foam plastic packaging material to meet the needs of shock absorption, cushioning, and heat preservation during storage and transportation of vegetables.

[0004] Currently, the representative technical solutions for preparing biodegradable materials using starch and plant fiber as raw materials mainly include the following: One approach discloses the application of lignin in the preparation of biodegradable foamed packaging materials, as described in CN112280265B. This method utilizes the numerous benzene ring structures within the lignin molecule, which can be transformed into natural aromatic polyesters through appropriate modification. These polyesters exhibit good compatibility with PBAT or PBST resins, which are also aromatic polyesters. Lignin is then mixed with biodegradable resin in a 1-100:100 ratio, along with small amounts of foaming agent, compatibilizer, and nucleating agent, and can be combined with 1-100 parts of filler to prepare biodegradable foamed packaging materials. From the above ratio, it can be calculated that the minimum amount of biodegradable resin used is still close to one-third. Although this method adds lignin and fillers in amounts roughly equivalent to the synthetic resin used, the amount of synthetic resin used remains relatively large, limiting the effect of reducing consumption and increasing efficiency, and requiring further improvement.

[0005] The second is CN105175794A, which discloses a starch-based foamed packaging material precursor, starch-based foamed packaging material, and preparation method. In this scheme, the amount of hydroxypropyl starch is 83-86 wt%, and the amount of plasticizer is 5-10 wt%. It also discloses the corresponding process parameters for a high-speed mixer and a twin-screw extruder, as well as a method for foaming and molding using microwave heating. The main material used in this scheme is hydroxypropyl starch. The preparation of hydroxypropyl starch requires modification of conventional starch-based substances, therefore its raw material cost is relatively high, and there is still considerable room for cost reduction.

[0006] Thirdly, CN104312182B discloses a biodegradable foamed packaging material and its preparation method. This method uses 8-10 parts of biodegradable resin, 70-80 parts of plant fiber, and 4-5 parts of inorganic powder, with the remainder being modifiers and foaming agents. This method significantly increases the amount of plant fiber used, but it requires ultrafine processing of the plant fiber. In particular, the processing cost of ultrafine processing using airflow milling is relatively high, and the overall cost remains high, leaving considerable room for cost reduction.

[0007] At the same time, regardless of the method used to produce biodegradable foamed packaging materials, they must all have corresponding cushioning, heat insulation, and shockproof properties. Summary of the Invention

[0008] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a foamed packaging material made from cold storage waste vegetables and cassava flour and its preparation method. By using waste vegetables from cold storage, adding cassava flour and some biodegradable auxiliary materials, the material is modified to transform it into a biodegradable foamed material. The foamed packaging material produced by this preparation method has good cushioning, heat insulation and shockproof performance.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: The foamed packaging material is composed of the following components by percentage: the material used is 100%, of which vegetable fiber is 20% to 35%, cassava flour is 30% to 40%, vegetable juice is 20% to 35%, plasticizer is 1% to 2%, nucleating agent is 2% to 5%, and release agent is 1% to 0.5%.

[0010] The plasticizer is glycerin, citric acid, or borax. The nucleating agent is calcium carbonate, talc, titanium dioxide, PCL, or PVA. The mold release agent is silicone oil, paraffin wax, or silica.

[0011] The above-mentioned method for preparing foamed packaging materials using leftover vegetables from cold storage and cassava flour includes the following steps: (1) Prepare raw materials according to the formula: vegetable fiber, cassava flour, vegetable juice, plasticizer, nucleating agent and release agent; (2) First, put the waste vegetables from the cold storage into the crushing and pulping machine for crushing and pulping; (3) Pass the vegetable pulp through a 60-mesh sieve to remove the stems and residue; (4) The sieved sauce is put into a centrifuge for solid-liquid separation to separate solid vegetable fiber and liquid vegetable juice; (5) Add plasticizer; (6) Take cassava flour, add it together with vegetable juice and plasticizer into a mixer, mix and stir, perform preliminary modification, and control the temperature at 60℃; (7) Add the solid vegetable fiber, nucleating agent, and release agent into the mixer and mix. (8) Further modify the mixed and modified materials in the mixer, start at low speed and gradually increase to 150 rpm within 5 minutes, and then gradually decrease to stop within 5 minutes, with the temperature controlled at 60℃; (9) Feed the material into the screw extruder and output it quantitatively into the die of the press, with the temperature controlled at 60°C to 70°C; (10) The material is heated and foamed in the molding mold under pressure. The heating temperature is 140℃ to 230℃ and the molding time is 2-3 minutes. (11) After depressurization, mold opening and demolding, foamed packaging materials can be obtained.

[0012] In the preliminary modification step (6), the mixer speed is 90 to 110 rpm, and the mixture is stirred for 8 to 12 minutes until it reaches a dough-like consistency. In step (9), the screw extruder is preferably a twin-screw extruder with a speed of 160 rpm, and the screw extruder is equipped with an electric heating device and a water cooling device. In step (10), the molding die is equipped with an electromagnetic coil for heating and a water pipe for cooling. The molding die is also equipped with a pressure locking mechanism and a steam pressure relief pipe, and the locking pressure of the pressure locking mechanism is 3 MPa to 5 MPa.

[0013] This invention completely eliminates the need for biodegradable resins and does not rely on petrochemical products. It uses only 30% to 40% cassava flour, significantly less than foaming materials primarily made from biodegradable starch, thus avoiding the process of converting cassava flour into starch and then modifying it. This invention utilizes the fiber separated from cold storage waste vegetables as a reinforcing component of the cassava flour foaming material, eliminating the need for ultrafine processing of the plant fibers in the waste vegetables. Furthermore, this invention uses the water contained in the vegetable juice separated from cold storage waste vegetables as a foaming agent for the cassava flour, saving the water required for biodegradable starch plastics, thus treating both solid waste and organic wastewater simultaneously. Compared to currently disclosed representative technical solutions, this invention significantly reduces material and process costs, possessing considerable economic and social value. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0015] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0016] The foamed packaging material is composed of the following components by percentage: the material used is 100%, of which vegetable fiber is 20% to 35%, cassava flour is 30% to 40%, vegetable juice is 20% to 35%, plasticizer is 1% to 2%, nucleating agent is 2% to 5%, and release agent is 1% to 0.5%.

[0017] The above-mentioned method for preparing foamed packaging materials using leftover vegetables from cold storage and cassava flour includes the following steps: (1) Prepare raw materials according to the formula: vegetable fiber, cassava flour, vegetable juice, plasticizer, nucleating agent and release agent; (2) First, put the waste vegetables from the cold storage into the crushing and pulping machine for crushing and pulping; (3) Pass the vegetable pulp through a 60-mesh sieve to remove the stems and residue; (4) The sieved sauce is put into a centrifuge for solid-liquid separation to separate solid vegetable fiber and liquid vegetable juice; (5) Add plasticizer; (6) Take cassava flour, add it together with vegetable juice and plasticizer into a mixer, mix and stir, perform preliminary modification, and control the temperature at 60℃; (7) Add the solid vegetable fiber, nucleating agent, and release agent into the mixer and mix. (8) Further modify the mixed and modified materials in the mixer, start at low speed and gradually increase to 150 rpm within 5 minutes, and then gradually decrease to stop within 5 minutes, with the temperature controlled at 60℃; (9) Feed the material into the screw extruder and output it quantitatively into the die of the press, with the temperature controlled at 60°C to 70°C; (10) The material is heated and foamed in the molding mold under pressure. The heating temperature is 140℃ to 230℃ and the molding time is 2-3 minutes. (11) After depressurization, mold opening and demolding, foamed packaging materials can be obtained.

[0018] In the preliminary modification step (6), the mixer speed is 90 to 110 rpm, and the mixture is stirred for 8 to 12 minutes until it reaches a dough-like consistency. In step (9), the screw extruder is preferably a twin-screw extruder with a speed of 160 rpm, and the screw extruder is equipped with an electric heating device and a water cooling device. In step (10), the molding die is equipped with an electromagnetic coil for heating and a water pipe for cooling. The molding die is also equipped with a pressure locking mechanism and a steam pressure relief pipe, and the locking pressure of the pressure locking mechanism is 3 MPa to 5 MPa.

[0019] The formulation ratio and molding parameters used in this invention are related to the product's density and impact strength, and can be used to prepare packaging materials with corresponding characteristics according to usage conditions and environmental requirements.

[0020] Example 1 describes a material formulation and molding conditions that achieve relatively high impact strength while maintaining low density: The material used is 100% vegetable fiber (35%), tapioca flour (30%), vegetable juice (27.5%), plasticizer (2%), nucleating agent (5%), and demolding agent (0.5%). The main molding parameters are: molding temperature 180℃, molding time 2.5 minutes, and molding pressure 3.5 MPa. The density of the molded material is 0.23 g / cm³. 3 Impact strength unit: 2.8 KJ / m 2 .

[0021] Example 2 describes a material formulation and molding conditions with relatively low density while maintaining high impact strength: The material used is 100% vegetable fiber (30%), tapioca flour (40%), vegetable juice (22%), plasticizer (2%), nucleating agent (5%), and demolding agent (1%). The main molding parameters are: molding temperature 150℃, molding time 3 minutes, and pressure 3.2 MPa. The density of the molded material is 0.28 g / cm³. 3 Impact strength unit: 3.3 KJ / m 2 .

[0022] Example 3 describes a material formulation and molding conditions for relatively high impact strength, based on a high proportion of vegetable fiber: The material used is 100% vegetable fiber, comprising 35% vegetable fiber, 37% tapioca flour, 20% vegetable juice, 2% plasticizer, 5% nucleating agent, and 1% demolding agent. The main molding parameters are: molding temperature 140℃, molding time 3 minutes, and molding pressure 3 MPa. The density of the molded material is 0.31 g / cm³. 3 Impact strength unit: 3.2 KJ / m 2 .

[0023] The density and impact strength of materials and products made with different formulations and molding parameters used in this invention are compared in the table below (material formulation ratio: weight percentage; temperature unit: °C; time unit: minutes; pressure unit: MPa; density unit: g / cm³). 3 Impact strength unit: KJ / m 2 ): Vegetable fiber Tapioca flour Vegetable juice plasticizers nucleating agent Release agent Molding temperature Molding time Molding pressure density Impact strength 20 40 35 1 3 1 230 2 5 0.22 2.3 20 40 32.5 2 5 0.5 210 2.5 5 0.28 2.5 30 40 26.5 1 2 0.5 170 2.5 3.5 0.30 2.7 30 40 22 2 5 1 150 3 3.2 0.28 3.3 30 35 28.5 1 5 0.5 190 2.5 3.8 0.30 2.8 30 35 31 1 2 1 200 2.5 4 0.28 2.5 30 30 35 1 3.5 0.5 230 2 5 0.23 2.3 30 30 32 2 5 1 210 2.5 4 0.28 2.5 25 40 30.5 1 3 0.5 200 2.5 3.8 0.29 2.6 25 40 27 2 5 1 180 2.5 3.5 0.30 2.7 25 35 35 1 3 1 230 2 5 0.25 2.2 25 35 35 2 2.5 0.5 230 2 5 0.25 2.1 35 30 31.5 1 2 0.5 200 2.5 3.2 0.28 2.1 35 35 22 2 5 1 150 3 3.2 0.28 3 35 40 20 1 3.5 0.5 140 3 3 0.30 3 35 37 20 2 5 1 140 3 3 0.31 3.2 35 30 31 1 2 1 200 2.5 4 0.29 2.6 35 30 27.5 2 5 0.5 180 2.5 3.5 0.23 2.8 As shown in the table above, the combination of the main raw materials and molding parameters of this invention can produce foamed packaging materials with a certain impact resistance. Various shapes can be made by selecting different molds according to market demand. The foamed material produced by this invention is no less effective than similar biodegradable foamed materials and their products in terms of cushioning, shock absorption, and heat insulation.

[0024] This invention completely eliminates the need for biodegradable resins and does not rely on petrochemical products. It uses only 30% to 40% cassava flour, significantly lower than starch-based foamed packaging materials that use over 80% starch, thus avoiding the process of converting cassava flour into starch and then modifying it. The invention utilizes 20% to 30% fiber separated from cold storage waste vegetables as a reinforcing component of the cassava flour foaming material, eliminating the need for ultra-fine processing of the plant fibers in the waste vegetables. Furthermore, it utilizes 20% to 35% vegetable juice separated from cold storage waste vegetables, using the water content in the juice as a foaming agent for the cassava flour, saving the water required for biodegradable starch plastics. This process treats both solid waste and organic wastewater. This invention uses 30% to 40% cassava flour mixed with 50% to 75% waste vegetables, and can manufacture foamed packaging materials and corresponding products using conventional equipment under certain process parameters. Compared to currently disclosed representative technologies, this invention significantly reduces material and process costs, possessing considerable economic and social value.

Claims

1. A foamed packaging material made from cold storage waste vegetables and tapioca flour, characterized in that, This foamed packaging material is composed of the following components by percentage: The materials used are 100%, of which, Vegetable fiber contains 20% to 35%, Tapioca flour accounts for 30% to 40%. Vegetable juice content is 20% to 35%. Plasticizer 1% to 2%, Nucleating agent 2% to 5%, Release agent 1% to 0.5%.

2. The foamed packaging material made from cold storage waste vegetables and cassava flour as described in claim 1, characterized in that, The plasticizer is glycerin, citric acid, or borax.

3. The foamed packaging material made from cold storage waste vegetables and cassava flour as described in claim 1, characterized in that, The nucleating agent is calcium carbonate, talc, titanium dioxide, PCL, or PVA.

4. The foamed packaging material made from cold storage waste and cassava flour as described in claim 1, characterized in that, The release agent is silicone oil, paraffin wax, or silica.

5. The method for preparing foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 1, characterized in that, Includes the following steps: (1) Prepare raw materials according to the formula: vegetable fiber, cassava flour, vegetable juice, plasticizer, nucleating agent and release agent; (2) First, put the waste vegetables from the cold storage into the crushing and pulping machine for crushing and pulping; (3) Pass the vegetable pulp through a 60-mesh sieve to remove the stems and residue; (4) The sieved sauce is put into a centrifuge for solid-liquid separation to separate solid vegetable fiber and liquid vegetable juice; (5) Add plasticizer; (6) Take cassava flour, add it together with vegetable juice and plasticizer into a mixer, mix and stir, perform preliminary modification, and control the temperature at 60℃; (7) Add the solid vegetable fiber, nucleating agent, and release agent into the mixer and mix. (8) Further modify the mixed and modified materials in the mixer, start at low speed and gradually increase to 150 rpm within 5 minutes, and then gradually decrease to stop within 5 minutes, with the temperature controlled at 60℃; (9) Feed the material into the screw extruder and output it quantitatively into the die of the press, with the temperature controlled at 60°C to 70°C; (10) The material is heated and foamed in the molding mold under pressure. The heating temperature is 140℃ to 230℃ and the molding time is 2-3 minutes. (11) After depressurization, mold opening and demolding, foamed packaging materials can be obtained.

6. The method for preparing foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 5, characterized in that, In the preliminary modification step (6), the mixer speed is 90 to 110 rpm, and the mixture is stirred for 8 to 12 minutes until it becomes doughy.

7. The method for preparing a foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 5, characterized in that, The screw extruder in step (9) is a twin-screw extruder with a rotation speed of 160 rpm.

8. The method for preparing foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 5, characterized in that, The screw extruder in step (9) is equipped with an electric heating device and a water cooling device.

9. The method for preparing foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 5, characterized in that, The molding die in step (10) is equipped with an electromagnetic coil for heating and a water pipe for cooling.

10. The method for preparing foamed packaging material using cold storage waste vegetables and cassava flour as described in claim 5, characterized in that, The molding die in step (10) is equipped with a pressure locking mechanism and a steam depressurization pipeline. The locking pressure of the pressure locking mechanism is 3 MPa to 5 MPa.

Images