Environment-friendly expandable polystyrene production process by extrusion method

Abstract

The application provides an environment-friendly expandable polystyrene production process by an extrusion method, and the process comprises the following steps: (1) optimizing a pre-treatment process according to the characteristics of polystyrene and historical treatment data of a historical treatment process to obtain an optimal pre-treatment process, and treating polystyrene by using the optimal pre-treatment process; (2) mixing polystyrene and additives to form a mixture by using a first process; (3) mixing and plasticizing the mixture to form a plasticized material by using a second process; (4) forming the plasticized material by using a third process; and (5) post-treating the plasticized material by using a fourth process. In the application, the pre-treatment process is optimized according to the characteristics of polystyrene material and historical treatment data, and different pre-treatment processes are used for recycled polystyrene materials with different characteristics, so that the process is more accurate, the recycling stability is improved, the cost is saved, and the dependence on manual experience is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high polymer materials, and particularly relates to an environment-friendly expandable polystyrene production process by an extrusion method. BACKGROUND

[0002] Polystyrene materials are widely used in the fields of electronic device shell packaging, daily necessities, toy products, foaming materials, home appliance packaging and external wall thermal insulation due to their excellent performance. However, waste polystyrene plastics are not easy to recycle and biodegrade, and have a long decomposition time, which leads to environmental pollution and resource waste, and does not conform to the sustainable development strategy of low carbon emission. Waste polystyrene plastics are derived from multiple sources, including industrial sources (waste materials in plastic forming and processing and waste industrial products), agricultural sources (waste agricultural mulch and agricultural pipelines), medical sources (one-time plastic products such as protective clothing and goggles) and living sources (one-time tableware and home appliance shells).

[0003] The quality and impurity content of recycled polystyrene vary significantly due to different sources, which leads to the need for different treatment methods and process parameters for different types of materials in the recycling and reuse process. However, many current recycling processes still rely on the experience and habits of operators, lack unified standards and processes, and lead to unstable treatment effects, affecting the quality of regenerated products. SUMMARY

[0004] The embodiment of the application provides an environment-friendly expandable polystyrene production process by an extrusion method, which comprises the following steps: (1) optimizing a pre-treatment process according to the characteristics of polystyrene and historical treatment data of a historical treatment process to obtain an optimal pre-treatment process, and treating polystyrene by using the optimal pre-treatment process; (2) mixing polystyrene and additives to form a mixed material by using a first process; (3) mixing and plasticizing the mixed material to form a plasticized material by using a second process; (4) forming the plasticized material by using a third process; and (5) treating the plasticized material by using a fourth process.

[0005] Further, the characteristics of polystyrene include the type, particle size, impurity content and impurity category of polystyrene.

[0006] Further, the historical treatment data includes a historical treatment process, a historical treatment time, a historical treatment frequency and a historical treatment effect.

[0007] Further, the optimization of the pre-treatment process comprises: selecting a corresponding historical treatment process according to the type, granularity, impurity content or impurity category of the polystyrene; selecting a first set of detection time nodes in the historical treatment process; obtaining a historical treatment effect at the first set of detection time nodes; treating the polystyrene according to the historical treatment process; detecting an actual treatment effect at the first set of detection time nodes; comparing the actual treatment effect with the historical treatment effect; obtaining an effect difference value; when the effect difference value is less than a preset difference value, the historical treatment process remains unchanged; and when the effect difference value is greater than the preset difference value, the historical treatment process is adjusted so that the effect difference value is less than the preset difference value.

[0008] Further, the optimization of the pre-treatment process comprises: selecting a corresponding historical treatment process according to the type, granularity, impurity content or impurity category of the polystyrene; treating the polystyrene according to the historical treatment process; detecting an actual treatment effect at a second set of detection time nodes; calculating a node detection value at the second set of detection time nodes according to the actual treatment effect; comparing the node detection values; taking a detection time node corresponding to a maximum node detection value as a key node; and adjusting the historical treatment process according to a time position of the key node.

[0009] Further, the node detection value is a difference value of the actual treatment effect within a unit time before and after a detection node.

[0010] Further, the first process comprises: mixing the polystyrene and the additive according to weight, wherein the weight proportion of the polystyrene is 20% to 95%, and the weight proportion of the additive is 5% to 80%.

[0011] Further, the second process comprises: melting the mixed material in an extruder, and then extruding the mixed material, wherein the working temperature of the extruder is 80℃ to 220℃, and the working pressure of the extruder is 3Mpa to 20Mpa.

[0012] Further, the third process comprises: cooling the plasticized material by using circulating water, wherein the temperature of the circulating water is 30℃ to 60℃.

[0013] Further, the fourth process comprises: drying the plasticized material.

[0014] The extrusion method environment-friendly expandable polystyrene production process optimizes the pre-treatment process according to the characteristics and historical treatment data of the polystyrene material, uses different pre-treatment processes for recycled polystyrene materials with different characteristics, so that the process is more accurate, the recovery stability is improved, the cost is saved, and the dependence on manual experience is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A flow chart of an extrusion method environment-friendly expandable polystyrene production process DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0017] For recycled polystyrene materials, pre-treatment processes are required before recycling. Due to the difference of recycled polystyrene materials, different pre-treatment processes are used. Generally, a person skilled in the art has certain corresponding processing methods for various recycled materials, but these processing methods are too dependent on personnel experience and habits, and the yield of material recycling is unstable with a large difference.

[0018] The characteristics of the recycled polystyrene material can include the type, particle size, impurity content or impurity category of the polystyrene material.

[0019] Generally, according to historical experience, according to different polystyrene recycled materials, after a large number of pre-treatment processes, historical treatment processes will be formed, and a large amount of historical treatment data will be retained. The historical treatment data includes historical treatment process, historical treatment time, historical treatment frequency and historical treatment effect, etc.

[0020] Specifically, the historical treatment process includes water washing, acid washing, alkali washing or organic washing, etc. The historical treatment time is the treatment time used for different historical treatment processes. The historical treatment frequency is the number of treatments or the number of treatments per unit time corresponding to different historical treatment processes. The historical treatment effect is the recovery rate or impurity rate of the recycled polystyrene after the pre-treatment process.

[0021] Embodiment 1

[0022] In this embodiment, the polystyrene pre-treatment process is described. By optimizing the pre-treatment process, the best pre-treatment process is obtained to refine the pre-treatment process, avoid the poor pre-treatment effect due to the difference of recycled materials, and avoid the dependence on personnel experience and habits, the unstable yield of material recycling and the large difference. Therefore, it is necessary to optimize the pre-treatment process. According to the characteristics of polystyrene and the historical treatment data, the pre-treatment process is optimized to obtain the best pre-treatment process, and the polystyrene material is treated by using the best pre-treatment process.

[0023] First, according to the characteristics of the recycled polystyrene, the historical treatment process with the highest frequency of use of the recycled polystyrene of this type in the historical treatment process is selected as the reference process.

[0024] The recycled polystyrene can include different types of polystyrene, for example, general-purpose polystyrene, high-impact polystyrene, foamed polystyrene, etc.

[0025] In this embodiment, the general-purpose polystyrene is taken as the historical treatment process, the cleaning time of each step in the process is taken as the treatment time, and the recovery rate of the general-purpose polystyrene is taken as the treatment effect. The pre-treatment process is optimized by optimizing the treatment process, the treatment time and the treatment effect.

[0026] In the second step, a detection time node is inserted in the historical treatment process, and the historical treatment effect at each time node is evaluated according to the historical treatment data corresponding to different time nodes.

[0027] The detection time node is determined according to the historical treatment time, and the initial time, the early time, the middle time, the late time and the end time of the historical treatment process are generally taken as the five detection time nodes. Of course, other time nodes can also be selected as the detection time nodes, which are not limited herein.

[0028] A set of detection time nodes are found out by selecting the historical pre-treatment process, for example, the detection time nodes are T1, T2, T3, T4 and T5, and the corresponding historical treatment effects are R1, R2, R3, R4 and R5. For example, the corresponding historical treatment effect is the recovery rate of polystyrene.

[0029] In the third step, the recycled polystyrene material is pre-treated according to the historical treatment process, and the actual treatment effect at each time node is obtained by sampling and detecting according to the detection time nodes in turn during the treatment process, for example, the actual recovery rates of polystyrene are R1', R2', R3', R4' and R5'.

[0030] In the fourth step, the data of the actual treatment effect and the historical treatment effect are compared to obtain the effect difference, wherein the effect difference is R1-R1', R2-R2', R3-R3', R4-R4' and R5-R5', respectively.

[0031] Suppose the preset difference value is M, that is, according to the characteristics of the recycled polystyrene, the effect difference between the actual polystyrene recovery rate and the historical polystyrene recovery rate at each detection time node is compared with the preset difference value M. When the effect difference is less than the preset difference value, the historical treatment process does not need to be adjusted, and the historical treatment process can be used as the best pre-treatment process, and the process is continued to be used to treat polystyrene. When the effect difference is greater than the preset difference value, it means that the historical treatment process cannot meet the current pre-treatment of the recycled polystyrene, and the historical pre-treatment process needs to be adjusted until the effect difference is less than the preset difference value.

[0032] Specifically, for example, when the effect difference at T2 is greater than the preset difference M, the time of the process flow step in which the time node is located needs to be increased, or a reagent is added in the process flow step in which the time node is located, so as to meet the requirement that the impurities to be cleaned in the polystyrene material are sufficiently cleaned, and the recovery rate of the polystyrene is increased.

[0033] Through the above steps, the pre-treatment process is optimized, and the optimized pre-treatment process is more suitable for the batch of recovered polystyrene material. Therefore, the optimized pre-treatment process is the best pre-treatment process, and the batch of polystyrene material is treated by using the best pre-treatment process.

[0034] Embodiment 2

[0035] In this embodiment, the pre-treatment process of the polystyrene material is described in detail. By optimizing the pre-treatment process, the key nodes are found out, and the pre-treatment process is adjusted according to the position of the key nodes in the historical treatment process, so as to obtain the best pre-treatment process.

[0036] First, according to the characteristics of the recovered polystyrene, the historical treatment process with the highest frequency of use of the recovered polystyrene of this kind in the historical treatment process is selected as the reference process.

[0037] Among them, the recovered polystyrene can include different kinds of polystyrene materials, such as general-purpose polystyrene, high-impact polystyrene, foamed polystyrene, etc.

[0038] In this embodiment, the caustic washing, acid washing, organic washing and water washing in the recovery of general-purpose polystyrene are taken as the treatment process, the cleaning time of each step in the process is taken as the treatment time, and the recovery rate of the general-purpose polystyrene is taken as the treatment effect. The pre-treatment process is optimized by optimizing the treatment process, the treatment time and the treatment effect.

[0039] Secondly, in the historical treatment process, detection time nodes are inserted, and the historical treatment effect at each time node is evaluated according to the historical treatment data corresponding to different time nodes.

[0040] Among them, the detection time nodes are determined according to the historical treatment time, and generally the initial time, the early time, the middle time, the late time and the end time of the historical treatment process are taken as the five detection time nodes. Of course, other time nodes can also be selected as the detection time nodes, which are not limited herein.

[0041] Through the selected historical pre-treatment process, a set of detection time nodes are found out, for example, the detection time nodes are T10, T20, T30, T40 and T50, and the corresponding actual treatment effects are R10, R20, R30, R40 and R50. For example, the corresponding historical treatment effect is the recovery rate of the polystyrene.

[0042] The detection time nodes are determined according to the time of the processing steps, and generally, the initial time T10, the preceding time T20, the middle time T30, the following time T40 and the final time T50 of the processing steps are taken as the five detection time nodes. Of course, other time nodes can be selected as the detection time nodes, which are not limited herein.

[0043] In the fourth step, the node detection values at the detection time nodes are calculated according to the actual processing effect, the node detection values are compared, the detection time node corresponding to the maximum node detection value is the key node, and the historical processing technology is adjusted according to the time position of the key node.

[0044] In one embodiment, the node detection value is the difference of the actual processing effect in the unit time before and after the detection node. For example, the node detection value at T10 is 2f1, where the actual effect is R10-f1 when the time node is T10-d1, and the actual effect is R10+f1 when the time node is T10+d1, d1 is the change value of the unit time, f1 is the change value of the actual effect in the unit time, the node detection value at T10 is 2f1. The node detection value at T20 is 2f2, where the actual effect is R20-f2 when the time node is T20-d1, and the actual effect is R20+f2 when the time node is T20+d1, the node detection value at T20 is 2f2. Similarly, the node detection value at T30 is 2f3, the node detection value at T40 is 2f4, and the node detection value at T50 is 2f5. If f2 is the maximum value, the detection time node T20 is the key node.

[0045] In another embodiment, according to the time of the detection time node and the actual processing effect, a curve of the actual processing effect about time is fitted, and the time node at the maximum curvature of the curve is taken as the key node. The key node is found according to the curve, which is more intuitive and improves the operation efficiency.

[0046] Specifically, if the detection time node position corresponding to the key node is in the first half of the step, the amount of the reagent added in the step is increased, and if the detection time node position corresponding to the key node is in the second half of the step, the processing time of the step is increased. The maximum curvature indicates that the reaction is more intense before the time node, and the reaction is balanced after the time node. If the processing effect is not up to standard, and the reaction is insufficient in the first half, the reagent needs to be increased; if it is in the second half, it indicates that the reaction time is not enough, and the reaction time needs to be increased.

[0047] Through the above steps, the pre-treatment process is optimized to obtain the best pre-treatment process, and the best pre-treatment process is used to process the batch of polystyrene materials.

[0048] Example 3

[0049] The first process mixes polystyrene material and additives to form a mixture. The first process specifically includes:

[0050] The recycled polystyrene is mixed with additives, wherein the recycled polystyrene is in the form of particles, the weight ratio of polystyrene is 20% to 95%, and the weight ratio of additives is 5% to 80%.

[0051] In one embodiment, the additives include one or more of nucleating agents, pentane, and colorants. The weight ratio of the nucleating agent can be 0.5% to 10%, the weight ratio of pentane can be 3% to 10%, and the weight ratio of the colorant can be 0.1% to 20%.

[0052] Specifically, the nucleating agent includes one or more of talc, polyethylene wax, kaolin, white carbon black, calcium carbonate, silicon dioxide, and precipitated silica.

[0053] The nucleating agent can help polystyrene form small crystalline nuclei during the recycling process, which can serve as the starting point for polymerization, thereby promoting the progress of the extrusion polymerization reaction. It can also improve the physical and mechanical properties of recycled polystyrene, such as impact resistance, transparency, and weather resistance. In addition, it can promote the crystallization morphology of the polymer and control the morphology and size of the polymer. In recycled polystyrene, this helps to obtain a more uniform and stable polymer structure, thereby further improving the performance of the material.

[0054] Pentane can be one or more of n-pentane and i-pentane, and if both are included, the ratio is preferably 1:9 to 9:1. Pentane acts as a solvent or diluent in polystyrene recycling, promotes foaming, regulates reaction speed and temperature, and affects the physical properties and processing properties of the material, all of which contribute to the effective recycling and reuse of polystyrene.

[0055] Example 4

[0056] The second process includes melting the mixture in an extruder and then extruding the mixture, wherein the working temperature of the extruder is 80°C to 220°C, and the working pressure of the extruder is 3Mpa to 20Mpa.

[0057] Specifically, the mixing and plasticizing process of polystyrene is mainly carried out by an extruder, which realizes the effective melting, mixing, and plasticizing of the material by precisely controlling the working temperature and pressure.

[0058] In one embodiment, the device can be a twin-screw extruder or a single-screw extruder.

[0059] For the twin-screw extruder, the machine working temperature can be 130°C to 200°C, specifically 130°C, 150°C, 180°C and 200°C, different working temperatures are related to the characteristics of polystyrene. The working pressure can be 3MPa to 20MPa. Under this working condition, it can ensure that the material is fully melted and uniformly mixed, and at the same time ensure that the material is subjected to sufficient shear force and mixing plasticizing effect during melting.

[0060] For the single-screw extruder, the machine working temperature can be 80°C to 220°C, specifically 80°C, 130°C, 180°C and 220°C, different working temperatures are related to the characteristics of polystyrene. The working pressure can be 4MPa to 10MPa, under this working condition, it can ensure that the material is fully melted and uniformly mixed, and at the same time ensure that the material is subjected to sufficient shear force and mixing effect during melting.

[0061] Example 5

[0062] The third process includes forming and plasticizing the material, specifically, the plasticized material is extruded from the head part of the extruder into the circulating water for underwater pelletizing, and is cut into particles of the required size according to the product specification, the particle size can be 0.4cm to 3.0cm. This process is usually operated under pressure, and the working pressure is 0.1Mpa to 2Mpa. The circulating water temperature is between 30°C to 60°C to ensure the stability of the pelletizing process and the product quality. The polystyrene particles after underwater pelletizing and centrifugal drying treatment have the advantages of uniform particle size, good dispersibility and flowability, etc.

[0063] Example 6

[0064] The fourth process includes drying the plasticized material. Specifically, after the underwater pelletizing process of the plasticized material, the particles with moisture enter an integrated dehydration dryer for further drying treatment, and the optional drying method is one or both of the lower dehydration method and the upper air suction method.

[0065] For the lower dehydration method, a dehydration dryer is preferred, which removes the residual moisture in the particles by mechanical or physical means. Usually realized by vibrating sieve plate or centrifugal force, etc., so that the particles roll or jump on the sieve plate, thereby throwing off the water attached to the surface.

[0066] For the upper air suction method, an air suction system is provided above the dehydration area. Through the negative pressure effect, the air containing moisture is sucked out, and at the same time, the natural cold air is introduced as circulating air. The natural cold air is filtered and contacted with the particles containing moisture, and the moisture on the surface of the particles is removed to achieve the drying effect.

[0067] In other embodiments, a normal temperature drying method can also be selected, in which the dehydration drying process is carried out at normal temperature, avoiding the damage of high temperature to the performance of the particles. At the same time, normal temperature drying also reduces energy consumption and production cost.

[0068] In another embodiment, a natural cold air circulation method is adopted, which uses natural cold air as circulating air, without the need for additional refrigeration equipment, reducing energy consumption. At the same time, the natural cold air can also ensure the cleanliness of the air during the drying process, avoiding secondary pollution to the particles.

[0069] In another embodiment, a combination of lower dehydration and upper air extraction is used to achieve efficient dehydration of the particles. This process not only removes the moisture on the surface of the particles, but also gradually removes the moisture inside the particles, achieving the desired drying effect.

[0070] The above embodiments are only preferred embodiments of the present application, and are not a limitation on the protection scope of the present application. Any changes made on the basis of the design principles of the present application and non-creative labor shall belong to the protection scope of the present application.

Claims

1. An environmentally friendly process for the production of expandable polystyrene by extrusion comprising the steps of: (1) optimizing the pre-treatment process according to the characteristics and historical treatment data of polystyrene to obtain the best pre-treatment process, and treating the polystyrene by using the best pre-treatment process; (2) mixing the polystyrene and additives by using a first process to form a mixture; (3) mixing and plasticizing the mixture by using a second process to form a plasticized material; (4) forming the plasticized material by using a third process; and (5) treating the plasticized material by using a fourth process; The optimization of the pre-treatment process includes selecting a corresponding historical treatment process according to the type, particle size, impurity content or impurity category of the polystyrene, selecting a first set of detection time nodes in the historical treatment process, obtaining the historical treatment effect at the first set of detection time nodes, treating the polystyrene according to the historical treatment process, detecting the actual treatment effect at the first set of detection time nodes, comparing the actual treatment effect with the historical treatment effect, obtaining the effect difference, when the effect difference is less than the preset difference, the historical treatment process remains unchanged, and when the effect difference is greater than the preset difference, the historical treatment process is adjusted so that the effect difference is less than the preset difference. The historical treatment process acquisition process includes obtaining historical experience of different polystyrene recyclates after pre-treatment process, and selecting the highest frequency of use of this type of recycled polystyrene as the historical treatment process; the historical treatment data includes historical treatment process, historical treatment time, historical treatment frequency and historical treatment effect; the historical treatment process includes water washing, acid washing, alkali washing or organic washing; the historical treatment time is the treatment time used by different historical treatment processes; the historical treatment frequency is the number of treatments corresponding to different historical treatment processes or the number of treatments per unit time; the historical treatment effect is the recovery rate or impurity rate of the polystyrene recovered after the pre-treatment process; the actual treatment effect is the actual recovery rate of the polystyrene; and the first set of detection time nodes includes initial time, early time, middle time, late time and end time of the historical treatment process as detection time nodes.

2. The production process of the environmentally friendly expandable polystyrene by extrusion method according to claim 1, wherein the characteristics of the polystyrene include the type, particle size, impurity content and impurity category of the polystyrene.

3. The production process of the environmentally friendly expandable polystyrene by extrusion method according to any one of claims 1-2, wherein the optimization of the pre-treatment process includes selecting a corresponding historical treatment process according to the type, particle size, impurity content or impurity category of the polystyrene, treating the polystyrene according to the historical treatment process, detecting the actual treatment effect at a second set of detection time nodes, calculating the node detection value at the second set of detection time nodes according to the actual treatment effect, comparing the node detection values, taking the detection time node corresponding to the maximum node detection value as the key node, and adjusting the historical treatment process according to the time position of the key node.

4. The environmentally friendly expandable polystyrene production process by extrusion method according to claim 3, wherein the node detection value is the difference of actual processing effect within a unit time before and after the second set of detection time nodes.

5. The extrusion process for eco-friendly expandable polystyrene production according to claim 1, wherein the first process comprises mixing polystyrene and additives by weight, wherein, The weight ratio of the polystyrene is 20% to 95%, and the weight ratio of the additive is 5% to 80%.

6. The extrusion process environmentally friendly expandable polystyrene production process according to claim 1, the second process comprising melting the mixed material in an extruder, and then extruding the mixed material, wherein, The working temperature of the extruder is 80°C to 220°C, and the working pressure of the extruder is 3Mpa to 20Mpa.

7. The extrusion process environmentally friendly expandable polystyrene production process according to claim 1, said third process comprising cooling the plasticized mass with recycled water, wherein, The temperature of the circulating water is 30°C to 60°C.

8. The environmentally friendly expandable polystyrene production process by extrusion method according to claim 1, wherein the fourth process comprises drying the plasticized material.

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