Method for recycling and reproducing waste foam box

Abstract

The invention relates to the field of waste foam box recovery and reproduction, in particular to a waste foam box recovery and reproduction method. Comprising the links of manual sorting and crushing pretreatment, ultrasonic cleaning pretreatment, biological enzyme deep cleaning, vacuum freezing dehydration, microwave hot melting regeneration, post-treatment and the like. Wherein in the biological enzyme deep cleaning, an enzyme preparation with a specific formula is adopted, and various pollutants are effectively decomposed by virtue of the synergistic effect of various enzymes; the vacuum freezing dehydration utilizes a low-temperature freezing and vacuum sublimation principle to accurately remove moisture, so that adverse effects on materials and enzyme activity are avoided; and efficient and precise temperature control heating melting and forming are achieved through microwave hot melting regeneration. Through experimental comparison, the regenerated foam product produced by the method is superior to a product obtained by a traditional recovery method in the aspects of dimensional precision, density, compressive strength, appearance quality and the like, can meet middle and high-end application requirements, reduces wastewater discharge and energy consumption in the recovery process, and has good environmental protection property and economic benefit.

Description

Technical Field

[0001] The invention relates to the field of recycling and reproducing waste foam boxes, and in particular to a recycling and reproducing method for waste foam boxes. Background Art

[0002] With the booming development of e-commerce and logistics industries, the amount of waste foam boxes is increasing. If not handled properly, it will not only occupy a large amount of land resources, but also easily cause white pollution. At present, there are many shortcomings in the recycling and reproduction methods of waste foam boxes.

[0003] In traditional recycling methods, chemical detergents are often used for cleaning, such as soaking and rinsing. Although some surface dirt can be removed, the detergents themselves may be corrosive and cause certain damage to the foam material. In addition, if the wastewater after cleaning is discharged directly without proper treatment, it will cause serious water pollution problems. At the same time, common dehydration methods often make it difficult to completely remove the moisture in the foam particles. The residual moisture can easily cause quality problems such as bubbles and affect product density and strength in the subsequent hot melt processing. Existing hot melt technologies mostly use electric heating and other methods, which have high energy consumption and inaccurate temperature control. For foam boxes whose main component is polystyrene, excessively high temperatures will cause them to decompose and produce harmful substances such as styrene monomers, which will not only endanger the health of operators, but also cause quality defects in recycled products. Summary of the invention

[0004] In view of the above problems, the present invention proposes a method for recycling and reproducing waste foam boxes. In the cleaning process, this scheme uses a combination of ultrasonic cleaning and bio-enzyme deep cleaning, which reduces the use of chemical detergents and reduces the degree of wastewater pollution. At the same time, vacuum freeze dehydration avoids the high energy consumption and possible secondary pollution of traditional high-temperature dehydration methods, making the entire recycling and reproduction process more environmentally friendly, and bio-enzyme deep cleaning can effectively remove a variety of stubborn pollutants and improve the purity of the regenerated foam; vacuum freeze dehydration makes the foam particles have extremely low water content and form a porous structure, which is conducive to uniform melting and good fluidity of the material during hot melting, thereby making the texture of the extruded product more uniform, and performance indicators such as density and compressive strength are effectively guaranteed.

[0005] A method for recycling and reproducing waste foam boxes, the specific steps are:

[0006] S1. Manual sorting: Manually remove mixed hard impurities and foam boxes that are seriously contaminated by chemical substances or overly broken.

[0007] S2. Crushing pretreatment: Use a double-shaft crusher to crush the sorted foam boxes into particles with a particle size of 3-8mm, and then pass through a vibrating screen with an aperture of 8mm to remove fine powder.

[0008] S3. Cleaning pretreatment: The foam particles after crushing pretreatment are passed through a cleaning tank for cleaning pretreatment to remove dust and loose pollutants on the surface of the foam particles.

[0009] Preferably, the cleaning tank has a built-in spiral agitator with a rotation speed of 80-120 rpm, and is equipped with a 20-40kHz ultrasonic transducer with an array power density of 0.8-1.5W / cm 2 .

[0010] The specific treatment steps are: inject clean water at 15-25℃ into the cleaning tank, immerse the foam particles completely in the water, turn on the ultrasonic device and spiral stirrer, and perform a cleaning operation for 8-12 minutes. During this process, the water flow rate is maintained at 0.3-0.5m / s through the circulation pump, and the cavitation effect of the ultrasound and the flushing effect of the water flow are used to effectively remove the dust and loose pollutants on the surface of the foam particles, preparing for the subsequent deep cleaning.

[0011] S4. Bio-enzyme deep cleaning: The pre-treated foam particles are mixed with the prepared bio-enzyme preparation for deep cleaning.

[0012] Traditional foam particle cleaning methods often rely on a large amount of chemical detergents. Although these detergents can remove some dirt, they have many disadvantages, such as possible corrosion to the foam particles themselves and environmental pollution caused by wastewater discharge. Bioenzyme preparations have efficient catalytic decomposition capabilities and only require a small amount of addition to achieve a good cleaning effect, thereby significantly reducing the use of chemical detergents. This not only reduces cleaning costs, but also alleviates water pollution problems caused by detergent emissions, making the entire cleaning process more environmentally friendly and sustainable; and because bioenzymes can specifically and efficiently decompose the corresponding pollutants, compared to cleaning methods that simply rely on physical flushing or use ordinary chemical detergents, the use of bioenzyme preparations can achieve a more thorough cleaning of foam particles in a shorter time, which can greatly improve the work efficiency of the cleaning process and speed up the entire process of recycling and reproducing waste foam boxes.

[0013] Preferably, the biological enzyme comprises the following components in parts by weight: 20-25% lipase, 12-18% amylase, 8-12% cellulase, 3-6% surfactant, 4-5% stabilizer, and 34-53% deionized water.

[0014] Preferably, the preparation method of the surfactant is: mixing sodium dodecyl sulfate and polyethylene glycol in a mass ratio of 1:1, adding 50°C deionized water to dissolve and stir to form a clear solution, wherein the sodium dodecyl sulfate is required to have a purity of more than 99% and the molecular weight of the polyethylene glycol is 600.

[0015] Foam particles usually have a certain degree of hydrophobicity, and their surfaces are not easily wetted by water, which makes it difficult for the cleaning liquid to fully contact the pollutants on the surface of the particles. Surfactants can significantly reduce the surface tension of water, making it easier to spread on the surface of foam particles, thereby enhancing the wettability of foam particles; and for organic pollutants such as oil attached to the surface of foam particles, surfactants can disperse them into tiny oil droplets through emulsification, so that they are suspended in the cleaning liquid to avoid re-aggregation and attachment to the surface of particles; and surfactants can improve the properties of the surface of foam particles, making it easier for biological enzymes to approach and adsorb on the surface of pollutants, thereby exerting their catalytic decomposition effect.

[0016] Preferably, the stabilizer is prepared from calcium chloride and glycerol in a mass ratio of 1:2.

[0017] Enzymes are biological macromolecules with specific three-dimensional structures, and their activity depends on this precise structure. During the foam particle cleaning process, environmental factors such as temperature, pH value changes and possible impurity interference may destroy the structure of the enzyme and make it inactive. Stabilizers can maintain the stability of the enzyme's conformation through specific interactions with enzyme molecules. In the cleaning system, possible heavy metal ions, oxidizing substances or other impurities that can affect enzyme activity may damage the enzyme molecules. Stabilizers can resist these external interferences through chelation, antioxidant and other mechanisms. Since stabilizers ensure the activity and structural stability of the enzyme, each time the enzyme comes into contact with pollutants on the surface of the foam particles, it can catalyze the decomposition reaction in a relatively fixed and efficient manner. In the process of batch cleaning of foam particles, there will be no uneven cleaning effect due to fluctuations in enzyme activity, ensuring that each batch of foam particles can be cleaned more evenly and thoroughly, ensuring the quality stability of the recycled foam raw materials.

[0018] Preferably, the preparation method of the biological enzyme is:

[0019] I. Basic enzyme solution preparation: weigh 20-25% lipase, 12-18% amylase, and 8-12% cellulase by weight, pour into a container and stir, add deionized water to 60% of the total mass, start a high-speed disperser, and introduce nitrogen protection at the same time, disperse for 10 minutes until no agglomeration is visible to the naked eye;

[0020] II. Adding surfactant: Add the surfactant solution to the base enzyme solution under stirring and continue stirring for 30 minutes to fully emulsify the interface;

[0021] III. Stabilizer mixing: Dissolve 1.5% anhydrous calcium chloride in deionized water to prepare a 10% mother solution, filter to remove insoluble matter, add 2.5% glycerol directly to the enzyme solution, then slowly add the calcium chloride mother solution, maintain the stirring speed at 1000 rpm, and react for 15 minutes;

[0022] IV. Filtration and sterilization: The enzyme solution is passed through a 0.22 μm polyethersulfone microporous filter membrane to remove microorganisms and impurities to obtain the prepared enzyme solution.

[0023] S5. Vacuum freeze dehydration: The cleaned foam particles are freeze dehydrated by passing through a freezing device.

[0024] Preferably, in the vacuum freeze dehydration process, the freezing process adopts a combination of liquid nitrogen spray pre-cooling and mechanical refrigeration, the foam particles are frozen in a fluidized bed for 1.5 hours to form a porous structure with a particle size of 2-5 mm, the vacuum degree of the freezing chamber is maintained at ≤80Pa during the dehydration process, the sublimation temperature is -10°C to 0°C, the dehydration time is controlled at 2-4 hours, and the final water content is ≤1.5%.

[0025] After the waste foam boxes have gone through the preliminary processes of crushing and cleaning, a certain amount of water often remains in the foam particles. Vacuum freeze dehydration uses a combination of low-temperature freezing and vacuum environment to cause the water to sublimate directly into water vapor in the form of ice crystals, which is then pumped out by a vacuum pump, thereby achieving deep dehydration of the foam particles and reducing their water content to an extremely low level. During the subsequent hot melt processing, the material can be evenly heated and melted, avoiding problems such as bubbles and local overheating caused by water, making the internal structure of the recycled foam product after extrusion more uniform, the density distribution consistent, and the appearance smoother and smoother, without obvious defects, thereby improving the overall quality of the product.

[0026] S6. Hot melt processing: The dehydrated foam particles are input into the hot melt equipment for heating and melting, and then extruded through a specific mold to form.

[0027] Preferably, the heating equipment in the hot melt process is a 2450MHz microwave generator with a power density of 5-8kW / m 3 The material stays in the spiral conveying channel for 30 seconds, and then the temperature rises to 160-180℃ and is extruded into shape by a twin-screw extruder.

[0028] S7, post-processing: After extrusion, the product is cut according to the predetermined specifications, the excess scraps are removed, and the product is shaped to make its appearance meet the requirements of the finished product and ensure dimensional accuracy.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The combination of ultrasonic cleaning and bio-enzyme deep cleaning reduces the use of chemical detergents and reduces the degree of wastewater pollution. The bio-enzyme deep cleaning can effectively remove a variety of stubborn pollutants and improve the purity of the regenerated foam.

[0031] Vacuum freeze dehydration avoids the high energy consumption and possible secondary pollution of traditional high-temperature dehydration methods, making the entire recycling and reproduction process more environmentally friendly. Vacuum freeze dehydration makes the foam particles have extremely low water content and forms a porous structure, which helps to achieve uniform melting and good fluidity of the material during hot melting, thereby making the texture of the extruded product more uniform, and performance indicators such as density and compressive strength are effectively guaranteed.

[0032] Compared with traditional electric heating or thermal oil heating methods, the application of microwave hot melt regeneration technology has higher heating efficiency, shortens heating time, reduces energy consumption, and at the same time reduces the emission of harmful substances such as styrene monomer, reducing the impact on the atmospheric environment. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are 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.

[0034] The present invention will be further described below in conjunction with the embodiments.

[0035] Example 1

[0036] Used foam boxes were collected from local logistics warehouses, with a total weight of about 500kg. The main material was polystyrene with varying degrees of contamination, including some foam boxes with a small amount of oil, dust and slight surface damage.

[0037] Recycling steps:

[0038] S1. Manual sorting: Arrange personnel to sort this batch of waste foam boxes, pick out impurities such as metal and glass mixed in, as well as seriously contaminated or overly broken foam boxes that do not meet the requirements, and sort out about 30kg of unusable materials in total;

[0039] S2, crushing pretreatment: put the remaining qualified foam boxes into a double-shaft crusher, set the blade angle of the tool to 40°, and the rotation speed to 1400 rpm. After crushing, screen through a vibrating screen with an aperture of 8 mm to obtain about 450 kg of foam particles with a particle size of 3-8 mm, which are collected for later use;

[0040] S3, ultrasonic cleaning pretreatment: put the collected foam particles into a stainless steel cleaning tank, set the speed of the spiral stirrer in the cleaning tank to 100 rpm, the frequency of the ultrasonic transducer array to 30 kHz, and the power density to 1.2 W / cm 2, inject 20℃ clean water to immerse the particles, turn on the equipment for 10 minutes of cleaning, and maintain the water flow rate at 0.4m / s through the circulation pump. After the cleaning, it is observed that the dust and loose dirt on the surface of the foam particles are basically removed;

[0041] S4, biological enzyme deep cleaning: according to the enzyme preparation formula (lipase 23%, amylase 15%, cellulase 10%, surfactant 5%, stabilizer 4%, deionized water 43%), 150L of enzyme preparation solution was prepared, mixed with the cleaned foam particles, put into a constant temperature water bath, adjusted the water temperature to 50°C, adjusted the pH value to 7.0 with buffer solution, set the stirring speed to 180 rpm, reacted for 45 minutes, and after the reaction, it was found that the removal rate of oil, starch and fiber pollutants on the surface of the foam particles reached 99.2%, and the cleaning effect was good;

[0042] S5. Vacuum freeze dehydration: Put the foam particles after deep cleaning into the fluidized bed, start the liquid nitrogen spray system for precooling, and start the mechanical refrigeration unit after the temperature starts to drop. After about 1.5 hours, the particle temperature drops to -22°C to form a porous structure. Then start the vacuum system, control the vacuum degree at 70Pa, adjust the sublimation temperature to -8°C, and maintain it for 3 hours. The water content of the foam particles is measured to be 1.3%, which meets the requirements of subsequent processes.

[0043] S6. Microwave hot melt regeneration: The dehydrated foam particles are sent into the microwave heating chamber through a screw conveyor. The frequency of the microwave generator is 2450MHz and the power density is set to 6.5kW / m 3 After 30 seconds of heating, the material temperature reached 172°C, and then the molten material was introduced into a twin-screw extruder (screw speed 35 rpm, melt pressure 1.1 MPa), and extruded through a flat die (gap width 3 mm) to obtain a continuous foam sheet with a smooth appearance and uniform texture;

[0044] S7, post-processing: Use a band saw to cut the extruded foam sheet, the saw tooth density is 12 teeth / inch, and the sheet is cut into a predetermined size by adjusting the saw parameters. After testing, the size deviation of the cut product is within ±0.8mm;

[0045] S8, Quality Inspection: Check the density, compressive strength and appearance of the product, and the measured density is 20.5kg / m 3 The compressive strength and breaking stress are 0.19MPa, there are no bubbles or cracks on the appearance, the surface roughness Ra is 1.2μm, and all indicators meet the quality standards, so it can be packaged and stored as high-quality packaging materials.

[0046] Example 2

[0047] We selected used foam boxes collected from different supermarkets and e-commerce delivery points, with a total weight of about 800kg. The material was mainly polystyrene. Some of the foam boxes had obvious food residue stains and dust pollution, and were damaged to varying degrees.

[0048] Recycling steps:

[0049] S1. Manual sorting: Arrange personnel to sort this batch of waste foam boxes, pick out impurities such as metal and glass mixed in, as well as seriously contaminated or overly broken foam boxes that do not meet the requirements, and sort out about 50kg of unusable materials in total;

[0050] S2, crushing pretreatment: the remaining qualified foam boxes are put into a double-shaft crusher, the blade angle of the tool is set to 38°, the rotation speed is 1350 rpm, and after crushing, they are screened by a vibrating screen with an aperture of 8 mm to obtain about 720 kg of foam particles with a particle size of 3-8 mm, which are collected for standby use;

[0051] S3, ultrasonic cleaning pretreatment: put the collected foam particles into a stainless steel cleaning tank, set the speed of the spiral stirrer in the cleaning tank to 90 rpm, the frequency of the ultrasonic transducer array to 35 kHz, and the power density to 1.0 W / cm 2 , inject clean water at 18℃ to immerse the particles, turn on the equipment for 11 minutes of cleaning, and maintain the water flow rate at 0.35m / s through the circulation pump. After the cleaning, it is observed that the dust and loose dirt on the surface of the foam particles are basically removed;

[0052] S4, biological enzyme deep cleaning: according to the enzyme preparation formula (lipase 22%, amylase 16%, cellulase 11%, surfactant 4.5%, stabilizer 4%, deionized water 42.5%), 200L of enzyme preparation solution was prepared, mixed with the cleaned foam particles, put into a constant temperature water bath, adjusted the water temperature to 48°C, adjusted the pH value to 7.0 with buffer solution, set the stirring speed to 160 rpm, reacted for 45 minutes, and after the reaction, it was found that the removal rate of oil, starch and fiber pollutants on the surface of the foam particles reached 99.0%, and the cleaning effect was good;

[0053] S5. Vacuum freeze dehydration: Put the foam particles after deep cleaning into the fluidized bed, start the liquid nitrogen spray system for precooling, and start the mechanical refrigeration unit after the temperature starts to drop. After about 1.5 hours, the particle temperature drops to -20°C to form a porous structure. Then start the vacuum system, control the vacuum degree at 65Pa, adjust the sublimation temperature to -6°C, and maintain it for 3 hours. The water content of the foam particles is measured to be 1.2%, which meets the requirements of subsequent processes.

[0054] S6. Microwave hot melt regeneration: The dehydrated foam particles are sent into the microwave heating chamber through a screw conveyor. The frequency of the microwave generator is 2450MHz and the power density is set to 6kW / m 3 After 30 seconds of heating, the material temperature reached 170°C, and then the molten material was introduced into a twin-screw extruder (screw speed 32 rpm, melt pressure 1 MPa), and extruded through a square die (side length 10 cm) to obtain a block foam product;

[0055] S7, post-processing: Use a hot cutter (temperature controlled at 150°C) to cut and shape the block product to meet the requirements and the size deviation is within ±1mm;

[0056] S8, Quality Inspection: Check the density, compressive strength and appearance of the product, and the measured density is 19.8kg / m 3 The compressive strength and breaking stress are 0.17MPa, there are no bubbles or cracks on the appearance, the surface roughness Ra is 1.4μm, and all indicators meet the quality standards. It can be packaged and stored as general packaging materials.

[0057] Example 3

[0058] Used foam boxes were collected from community recycling stations and surrounding small businesses, with a total weight of about 300kg. The material was mainly polystyrene, and the types of pollution were various, including oil stains, traces of paint, and some fiber impurities attached. The integrity of the foam boxes varied greatly.

[0059] Recycling steps:

[0060] S1. Manual sorting: Arrange personnel to sort this batch of waste foam boxes, pick out impurities such as metal and glass mixed in, as well as seriously contaminated or overly broken foam boxes that do not meet the requirements, and sort out about 20kg of unusable materials in total;

[0061] S2, crushing pretreatment: the remaining qualified foam boxes are put into a double-shaft crusher, the blade angle of the tool is set to 35°, the rotation speed is 1300 rpm, and after crushing, they are screened by a vibrating screen with an aperture of 8 mm to obtain about 270 kg of foam particles with a particle size of 3-8 mm, which are collected for standby use;

[0062] S3, ultrasonic cleaning pretreatment: put the collected foam particles into a stainless steel cleaning tank, set the speed of the spiral stirrer in the cleaning tank to 110 rpm, the frequency of the ultrasonic transducer array to 25 kHz, and the power density to 1.3 W / cm 2 , inject clean water at 22℃ to immerse the particles, turn on the equipment for 9 minutes of cleaning, and maintain the water flow rate at 0.45m / s through the circulation pump. After the cleaning, it is observed that the dust and loose dirt on the surface of the foam particles are significantly reduced;

[0063] S4, biological enzyme deep cleaning: according to the enzyme preparation formula (lipase 24%, amylase 14%, cellulase 9%, surfactant 5%, stabilizer 4.5%, deionized water 43.5%), 90L of enzyme preparation solution was prepared, mixed with the cleaned foam particles, put into a constant temperature water bath, adjusted the water temperature to 52°C, adjusted the pH value to 7.0 with buffer solution, set the stirring speed to 190 rpm, reacted for 45 minutes, and after the reaction, it was found that the removal rate of oil, starch and fiber pollutants on the surface of the foam particles reached 99.3%, and the cleaning effect was good;

[0064] S5. Vacuum freeze dehydration: Put the foam particles after deep cleaning into the fluidized bed, start the liquid nitrogen spray system for precooling, and start the mechanical refrigeration unit after the temperature starts to drop. After about 1.5 hours, the particle temperature drops to -25°C to form a porous structure. Then start the vacuum system, control the vacuum degree at 80Pa, adjust the sublimation temperature to -10°C, and maintain it for 3 hours. The water content of the foam particles is measured to be 1.4%, which meets the requirements of subsequent processes.

[0065] S6. Microwave hot melt regeneration: The dehydrated foam particles are sent into the microwave heating chamber through a screw conveyor. The microwave generator frequency is 2450MHz and the power density is set to 7kW / m 3 After 30 seconds of heating, the material temperature reached 175°C, and then the molten material was introduced into a twin-screw extruder (screw speed 38 rpm, melt pressure 1.2 MPa), and extruded through a circular die (diameter 8 cm) to obtain a cylindrical foam product;

[0066] S7, post-processing: Use a band saw to cut the extruded foam sheet, the saw tooth density is 12 teeth / inch, and the sheet is cut into a predetermined size by adjusting the saw parameters. After testing, the size deviation of the cut product is within ±0.9mm;

[0067] S8, Quality Inspection: Check the density, compressive strength and appearance of the product, and the density is 21kg / m 3 The compressive strength and breaking stress are 0.2MPa, there are no bubbles or cracks on the appearance, the surface roughness Ra is 1.1μm, and all indicators meet the quality standards. It can be packaged and stored as a building insulation material.

[0068] Comparative Example

[0069] Waste foam boxes from the same source as in Example 1 were selected, with a total weight of about 500 kg, and also included polystyrene foam boxes with different degrees of contamination and damage.

[0070] Recycling steps:

[0071] S1. Manual sorting: Arrange personnel to sort this batch of waste foam boxes, pick out impurities such as metal and glass mixed in, as well as seriously contaminated or overly broken foam boxes that do not meet the requirements, and sort out about 30kg of unusable materials in total;

[0072] S2, crushing pretreatment: put the remaining qualified foam boxes into a double-shaft crusher, set the blade angle of the tool to 40°, and the rotation speed to 1400 rpm. After crushing, screen through a vibrating screen with an aperture of 8 mm to obtain about 450 kg of foam particles with a particle size of 3-8 mm, which are collected for later use;

[0073] S3. Chemical detergent cleaning: Use conventional chemical detergent to soak and clean the foam particles for 30 minutes, then rinse twice with clean water.

[0074] S4, centrifugal dehydration: use a centrifugal dehydrator to dehydrate for 10 minutes, and the final water content of the foam particles is about 8%;

[0075] S5, hot melt processing: the foam particles are hot melted by electric heating, the heating temperature is controlled at about 180°C, the heating time is about 40 seconds, and then the melted material is introduced into a twin-screw extruder (screw speed 35 rpm, melt pressure 1.1 MPa), and extruded through a flat die (gap width 3mm). The final extruded foam sheet has a rough appearance, obvious bubbles and uneven thickness;

[0076] S7, post-processing: Use a band saw to cut the extruded foam sheet. The saw tooth density is 12 teeth / inch. By adjusting the saw parameters, the sheet is cut into a predetermined size. After testing, the size deviation of the cut product is about ±0.8mm.

[0077] S8, Quality Inspection: Check the density, compressive strength and appearance of the product, and the density is 18kg / m 3 The compressive strength failure stress is 0.12 MPa, there are many defects in the appearance, the surface roughness Ra is about 2.0 μm, and the product quality is far lower than the product produced in Example 1. It is difficult to meet the use requirements of the mid-to-high-end market and can only be used in some packaging scenarios with lower quality requirements.

[0078] Table 1: Product quality inspection results of Example 1 and Comparative Example

[0079]

[0080]

[0081] By comparing the quality inspection result table of the above-mentioned embodiment 1 with the comparative example, it can be clearly seen that the foam box recycled and reproduced by the improved process of this patent is superior to the comparative example finished product using the conventional process in multiple indicators, such as product density, strength (compressive strength and breaking stress), appearance, etc. This fully demonstrates the good effect of the improved method of this patent in improving product quality, etc.

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0083] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for recycling and reproducing waste foam boxes, characterized in that: The following steps are involved: S1. Manual sorting: Manually remove mixed hard impurities, as well as foam boxes that are seriously contaminated by chemical substances or overly broken; S2. Crushing pretreatment: Use a double-shaft crusher to crush the sorted foam boxes into particles with a particle size of 3-8mm, and then pass through a vibrating screen with an aperture of 8mm to remove fine powder; S3, cleaning pretreatment: the foam particles after crushing pretreatment are passed through a cleaning tank for cleaning pretreatment to remove dust and loose pollutants on the surface of the foam particles; S4, biological enzyme deep cleaning: the pre-treated foam particles are mixed with the prepared biological enzyme preparation for deep cleaning; S5, vacuum freeze dehydration: the washed foam particles are passed through a freezing device for freeze dehydration; S6, hot melt processing: the dehydrated foam particles are input into the hot melt equipment for heating and melting, and then extruded through a specific mold to form after melting; S7, post-processing: After extrusion, the product is cut according to the predetermined specifications, the excess scraps are removed, and the product is shaped to make its appearance meet the requirements of the finished product and ensure dimensional accuracy.

2. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: The cleaning tank has a built-in spiral stirrer with a rotation speed of 80-120 rpm and is equipped with a 20-40kHz ultrasonic transducer with an array power density of 0.8-1.5W / cm 2 .

3. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: The specific method of the cleaning pretreatment is: Use 15-25℃ clean water to immerse the foam particles, keep the cleaning time for 8-12 minutes, maintain the water flow rate at 0.3-0.5m / s through the circulation pump, and remove dust and loose pollutants on the surface of the foam particles.

4. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: The biological enzyme comprises the following components in parts by weight: 20-25% of lipase, 12-18% of amylase, 8-12% of cellulase, 3-6% of surfactant, 4-5% of stabilizer and 34-53% of deionized water.

5. The method for recycling and reproducing waste foam boxes according to claim 4, characterized in that: The preparation method of the surfactant is as follows: sodium dodecyl sulfate and polyethylene glycol are mixed in a mass ratio of 1:1, and 50° C. deionized water is added to dissolve and stir to form a clear solution, wherein the sodium dodecyl sulfate is required to have a purity of more than 99%, and the molecular weight of the polyethylene glycol is 600.

6. The method for recycling and reproducing waste foam boxes according to claim 4, characterized in that: The stabilizer is prepared from calcium chloride and glycerol in a mass ratio of 1:

2.

7. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: The preparation method of the biological enzyme is: I. Basic enzyme solution preparation: weigh 20-25% lipase, 12-18% amylase, and 8-12% cellulase by weight, pour into a container and stir, add deionized water to 60% of the total mass, start a high-speed disperser, and introduce nitrogen protection at the same time, disperse for 10 minutes until no agglomeration is visible to the naked eye; II. Adding surfactant: Add the surfactant solution to the base enzyme solution under stirring and continue stirring for 30 minutes to fully emulsify the interface; III. Stabilizer mixing: Dissolve 1.5% anhydrous calcium chloride in deionized water to prepare a 10% mother solution, filter to remove insoluble matter, add 2.5% glycerol directly to the enzyme solution, then slowly add the calcium chloride mother solution, maintain the stirring speed at 1000 rpm, and react for 15 minutes; IV. Filtration and sterilization: The enzyme solution is passed through a 0.22 μm polyethersulfone microporous filter membrane to remove microorganisms and impurities to obtain the prepared enzyme solution.

8. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: In the vacuum freeze dehydration process, the freezing process adopts a combination of liquid nitrogen spray precooling and mechanical refrigeration. The foam particles are frozen in a fluidized bed for 1.5 hours to form a porous structure with a particle size of 2-5 mm. During the dehydration process, the vacuum degree of the freezing chamber is maintained at ≤80Pa, the sublimation temperature is -10°C to 0°C, the dehydration time is controlled at 2-4 hours, and the final water content is ≤1.5%.

9. The method for recycling and reproducing waste foam boxes according to claim 1, characterized in that: The heating equipment in the hot melt process is a 2450MHz microwave generator with a power density of 5-8kW / m 3 The material stays in the spiral conveying channel for 30 seconds, and then the temperature rises to 160-180℃ and is extruded into shape by a twin-screw extruder.

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