Waste plastic treatment device and treatment method

Abstract

The present invention relates to a waste plastic processing system comprising: a dissolution reactor that dissolves a polymer contained in the waste plastic by stirring a solvent and waste plastic; a precipitator that precipitates the polymer by supplying a solution in which the polymer is dissolved to a container in which a non-solvent is stored; a dryer that receives the precipitated polymer and removes one or more of the solvent and the non-solvent contained in the polymer; a measuring instrument that samples the dried polymer and measures the color intensity of the polymer sample; and a controller that controls the drying conditions of the dryer by comparing the color intensity of the polymer sample measured by the measuring instrument with a reference value.

Description

Technology Field

[0001] The present invention relates to a waste plastic treatment system and a process thereof. Specifically, the present invention relates to a waste plastic treatment system and a process thereof that reduces the amount of residual solvent and non-solvent of recycled polymers. Background Technology

[0002] Generally, when recyclable plastic waste is received at a collection center for recycling, it differs significantly in characteristics, mainly being flame-retardant or non-flame-retardant. Various materials are mixed within each category, and in terms of color, recycled plastic waste of various colors such as white, black, and red is received in a mixed state.

[0003] The plastic recycling process removed impurities by passing the plastic through the stages of crushing, melting, sedimentation (or precipitation), and drying.

[0004] More specifically, the conventional plastic recycling process involves supplying a solution in which plastic is dissolved into a container containing a non-solvent to precipitate and precipitate the polymer, and then collecting and drying the precipitated polymer to remove the non-solvent in order to produce recycled plastic.

[0005] Conventional plastic recycling processes remove nonsolvents solely through drying, which leads to the problem of residual nonsolvents in the recycled plastic. Additionally, conventional processes suffer from the issue of varying moisture content among polymer particles during the drying stage due to the inconsistent particle size of the precipitated polymers. Prior art literature

[0006] Korean Patent Publication No. 10-2010-7025766 The problem to be solved

[0007] The present invention aims to solve the problems of the prior art by providing a waste plastic treatment system and process capable of minimizing the amount of solvent and non-solvent remaining in the polymer by controlling the drying conditions of the polymer in real time. means of solving the problem

[0008] One embodiment of the present invention provides a waste plastic treatment system comprising: a dissolution reactor that dissolves a polymer contained in the waste plastic by stirring a solvent and waste plastic; a precipitator that precipitates the polymer by supplying a solution in which the polymer is dissolved to a container in which a non-solvent is stored; a dryer that receives the precipitated polymer and removes one or more of the solvent and the non-solvent contained in the polymer; a measuring instrument that samples the dried polymer and measures the color intensity of the polymer sample; and a controller that controls the drying conditions of the dryer by comparing the color intensity of the polymer sample measured by the measuring instrument with a reference value.

[0009] One embodiment of the present invention provides a waste plastic processing system in which the measuring device comprises a bezel for storing the polymer sample, a light irradiation unit for irradiating light onto the polymer sample, and a sensor for measuring the color of the polymer sample.

[0010] One embodiment of the present invention provides a waste plastic treatment system that includes one or more flow paths through which the polymer moves, connecting the dryer and the measuring instrument.

[0011] One embodiment of the present invention provides a waste plastic treatment system in which the flow path comprises a supply flow path through which the polymer is transferred from the dryer to the measuring instrument and a discharge flow path through which the polymer is discharged from the measuring instrument to the dryer.

[0012] One embodiment of the present invention provides a waste plastic treatment system in which the flow path is a single flow path that supplies the polymer to the measuring instrument and discharges the polymer from the measuring instrument.

[0013] One embodiment of the present invention provides a waste plastic processing system in which the chromaticity value measured by the measuring instrument is selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space; at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space; at least one of the R value, G value, and B value of the RGB color space; and a combination thereof.

[0014] Another embodiment of the present invention provides a waste plastic treatment process comprising: a dissolution step of stirring a solvent and waste plastic to dissolve a polymer contained in the waste plastic; a precipitation step of supplying a solution in which the polymer is dissolved to a container in which a non-solvent is stored to precipitate the polymer; a drying step of drying the precipitated polymer to remove the non-solvent remaining in the polymer; a measurement step of sampling the dried polymer to prepare a polymer sample and measuring the color of the polymer sample; and a control step of controlling the drying conditions of the polymer by comparing the measured color of the polymer sample with a reference value.

[0015] Another embodiment of the present invention provides a waste plastic treatment process in which the control step increases one or more of the drying temperature and drying time of the polymer when the color of the measured polymer sample exceeds the reference value.

[0016] Another embodiment of the present invention provides a waste plastic treatment process in which the control step maintains the drying conditions of the polymer when the color of the measured polymer sample is equal to or less than the reference value.

[0017] Another embodiment of the present invention provides a waste plastic treatment process in which the chromaticity value measured in the measurement step is selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space; at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space; at least one of the R value, G value, and B value of the RGB color space; and a combination thereof. Effects of the invention

[0018] According to the waste plastic treatment system and process according to the embodiments of the present invention, the drying conditions of the polymer are controlled in real time to minimize the amount of solvent and non-solvent remaining in the polymer, thereby increasing the purity of the polymer contained in the recycled plastic. Brief explanation of the drawing

[0019] FIG. 1 is a drawing illustrating a waste plastic processing system according to one embodiment of the present invention. FIG. 2 is a drawing illustrating a dissolution reactor according to one embodiment of the present invention. FIG. 3 is a drawing illustrating a precipitation reactor according to one embodiment of the present invention. FIG. 4(a) is a drawing illustrating a dryer according to one embodiment of the present invention, and FIG. 4(b) is a drawing illustrating a dryer according to another embodiment of the present invention. FIG. 5 is a drawing illustrating a measuring instrument according to one embodiment of the present invention. FIG. 6 is a flowchart of a waste plastic treatment process according to one embodiment of the present invention. FIG. 7 is a detailed flowchart of the measurement step and control step according to one embodiment of the present invention. Specific details for implementing the invention

[0020] The detailed description of the present invention is intended to fully explain the invention to those skilled in the art. Throughout the specification, when a part is described as “comprising” a certain component or “featuring” a certain structure and shape, this does not mean that other components are excluded or other structures and shapes are excluded unless specifically stated otherwise, but rather that other components, structures, and shapes may be included.

[0021] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are presented and described in detail in the detailed description. However, this is not intended to limit the scope of the invention by the embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0022] The present invention will be described in detail below with reference to the drawings. However, the drawings are intended to illustrate the invention, and the scope of the invention is not limited by the drawings.

[0024] FIG. 1 is a drawing illustrating a waste plastic treatment system (100) according to one embodiment of the present invention. The waste plastic treatment system (100) may include a melting reactor (10), a precipitation reactor (20), a dryer (30), a measuring instrument (40), and a controller (50).

[0025] FIG. 2 is a drawing illustrating a dissolution reactor (10) according to one embodiment of the present invention. The dissolution reactor (10) dissolves waste plastic in a solvent, and can produce a solution (or a dissolved substance) in which the waste plastic is dissolved in the solvent by mixing the solvent and the waste plastic. The dissolved substance may refer to a solution in which a plasticizer, vinyl chloride polymer (PVC), additive, other plastics or additives contained in the waste plastic are dissolved in the solvent.

[0026] More specifically, a dissolved product refers to a product in which the polymers contained in waste plastic are dissolved by mixing the waste plastic with a positive solvent (or solvent) that has high solubility for the polymers contained in the waste plastic. When the polymers contained in the waste plastic dissolve in a solvent, physical bonds such as those formed by dipole moments between chains and hydrophobic bonds weaken, causing the chains to unravel and increase their degrees of freedom, thereby releasing additives such as plasticizers that were trapped within the chains.

[0027] Here, the polymer may include any one of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), and acrylonitrile butadiene styrene copolymer (ABS).

[0028] The dissolution reactor (10) may include a main body (11) and a stirrer (12).

[0029] The main body (11) receives and accommodates a solvent and waste plastic, and can store one or more of the solvent, waste plastic and a dissolved waste plastic.

[0030] The main body (11) may be provided with a solvent supply unit (not shown) and a waste plastic supply unit (not shown) on the top or side for supplying solvent and waste plastic, and may be provided with a dissolved material discharge unit (not shown) on the bottom for discharging dissolved material. Additionally, the dissolved material discharge unit may include a plate-shaped filter inside to filter out foreign substances remaining in the dissolved material.

[0031] Additionally, the stirrer (12) is included within the main body (11) and can mix the solvent and waste plastic by rotation to dissolve the waste plastic in the solvent. The stirrer (12) rotates around the central axis of the main body (11) and generates a fluid flow in the solvent, thereby increasing the contact area between the solvent and the waste plastic.

[0032] In one embodiment, the stirrer (12) is provided with at least one propeller on a long rod, and the propeller may be positioned along the length of the rod. Additionally, the stirrer (12) may include a motor capable of providing power to the rod to rotate the propeller. Accordingly, the stirrer (12) may be provided with the motor and the rod connected.

[0033] The stirrer (12) can be positioned so that the propeller is immersed in the solvent or solution, and can rotate the rod and propeller by receiving power from a motor to stir the solvent and waste plastic.

[0034] In another embodiment, the stirrer (12) may be provided with a rotating shaft (not shown) positioned horizontally with respect to the central axis of the main body (11) on one side of the motor, and a plurality of connecting parts (not shown) extending from the end of the rotating shaft toward the inner surface of the main body (11), with a rotating blade (not shown) connected to each connecting part.

[0035] The stirrer (12) according to the present invention is not specifically limited in shape as long as it can rotate a solution in which waste plastic is dissolved in a solvent in one direction.

[0037] FIG. 3 is a drawing illustrating a precipitation reactor (20) according to one embodiment of the present invention. The precipitation reactor (20) can precipitate a polymer by mixing a non-solvent with a solution in which waste plastic is dissolved in a solvent in a dissolution reactor (10). The precipitation reactor (20) stores a non-solvent and precipitates recycled plastic particles through the non-solvent, and may include a precipitation reactor body (21) and a solution supply unit (22). Here, the non-solvent refers to a compound in which the Hansen Solubility Parameter (HSP) of the polymer contained in the waste plastic is 10 or higher.

[0038] The precipitation reactor (20) can precipitate recycled plastic from which additives contained in the melt have been removed by mixing the non-solvent stored in the precipitation reactor body (21) with the melt supplied from the melt supply unit.

[0039] Accordingly, the precipitation reactor body (21) stores a non-solvent with low solubility for the polymer contained in the waste plastic, so when a drop of the dissolved material supplied from the dissolved material supply unit (22) falls into the non-solvent, the polymer within the drop of the dissolved material does not dissolve in the non-solvent and precipitates as fine recycled plastic particles. Conversely, the non-solvent has high solubility for additives such as plasticizers, so the additives such as plasticizers contained in the drop of the dissolved material dissolve in the non-solvent, increasing the purity of the precipitated fine particles. That is, the recycled plastic particles precipitated in the precipitation reactor (20) may refer to polymer particles contained in the waste plastic.

[0040] The precipitation reactor (20) can precipitate a polymer with low solubility by contacting and mixing the dissolved material with a non-solvent to increase the ratio of the non-solvent to the dissolved material and decreasing the polymer solubility of the dissolved material.

[0041] The precipitation reactor (20) may include a stirrer (not shown) within the precipitation reactor body that stores the non-solvent and the precipitated recycled plastic particles. The stirrer is located within the precipitation reactor body and can mix the non-solvent and the dissolved material by rotation.

[0042] In the precipitation reactor (20), the dissolved material falls into the non-solvent, and at the same time, the dissolved material and the non-solvent are mixed and recycled plastic particles or polymer particles may be precipitated, but the polymer dissolved in the dissolved material may remain. Therefore, the stirrer can increase the efficiency of precipitating the polymer dissolved in the dissolved material by stirring the non-solvent supplied with the dissolved material to increase the contact rate between the non-solvent and the dissolved material.

[0043] The precipitation reactor (20) may further include a non-solvent inlet (not shown) for injecting a non-solvent into the body of the precipitation reactor. As the dissolved material is supplied, the concentration of the non-solvent stored in the body of the precipitation reactor (20) may decrease. Accordingly, the non-solvent inlet may inject a non-solvent into the body of the precipitation reactor to maintain the concentration of the non-solvent stored in the precipitation reactor (20).

[0044] Waste plastic may be waste polyvinyl chloride. A non-solvent refers to a compound in which the Hansen Solubility Parameter (HSP) of polyvinyl chloride is 10 or higher.

[0045] Specifically, a nonsolvent refers to a compound in which the Hansen Solubility Parameter (HSP) of polyvinyl chloride is 10 or more and 20 or less.

[0046] In this context, the Hansen solubility factor of polyvinyl chloride refers to the difference in Hansen parameters between the solute and the solvent. The Hansen solubility factor is a value proportional to the solubility of the two substances, allowing for the calculation of their solubility. The more similar the properties of the two substances, the more similar their Hansen parameter values ​​are; consequently, the lower the HSP value, and based on this HSP value, it can be predicted that these two substances will dissolve well together.

[0047] The Hansen solubility factor can be calculated using the following formula. When using HSPip software that calculates this conveniently, the δd, δp, and δh of the two substances can be obtained, and by applying these values ​​to the following formula, the HSP value with the corresponding solvent can be calculated.

[0048]

[0049] In one embodiment of the present invention, the nonsolvent is a hydrocarbon compound comprising one or more selected from the group consisting of alcohol, ether, cycloalkane, ester, carboxylic acid, nitrile, hexane, and chloroform.

[0050] In one embodiment of the present invention, the non-solvent is ethanol, methanol, hexane, isopropyl alcohol, ethyl acetate, or acetonitrile.

[0051] In one embodiment of the present invention, the non-solvent is preferably ethanol, methanol, hexane, or isopropyl alcohol.

[0052] In one embodiment of the present invention, the solvent of polyvinyl chloride is a ketone-based solvent, a cycloether-based solvent, a linear or cyclic carbonate-based solvent, or a hydrocarbon-based solvent having 1 to 10 carbon atoms.

[0053] Ketone-based solvents can be, for example, methyl ethyl ketone.

[0054] Cycloether-based solvents can be, for example, tetrahydrofuran.

[0055] In one embodiment of the present invention, the linear carbonate-based solvent may be dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC) or methyl propyl carbonate (MPC), but is not limited thereto.

[0056] In one embodiment of the present invention, the cyclic carbonate-based solvent may be ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate (BC), 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate (VC), vinylethylene carbonate, or fluoroethylene carbonate, but is not limited thereto. Preferably, the cyclic carbonate-based solvent may be propylene carbonate.

[0057] In one embodiment of the present invention, the hydrocarbon solvent having 1 to 10 carbon atoms may be methylene chloride or ethylene chloride, but is not limited thereto.

[0058] In one embodiment of the present invention, the solvent of polyvinyl chloride is preferably methyl ethyl ketone, cyclohexanone, or cyclohexane.

[0060] The dryer (30) receives the precipitated polymer and removes one or more of the solvent and non-solvent contained in the polymer.

[0061] FIG. 4(a) is a drawing showing a dryer (30) according to one embodiment of the present invention, and FIG. 4(b) is a drawing showing a dryer (30) according to another embodiment of the present invention.

[0062] A dryer (30) according to one embodiment may include a housing (31) for receiving a polymer supplied from a precipitation reactor (20) and a heat source for heating the housing (31).

[0063] The heat source heats the housing (31) to increase the internal temperature of the housing (31), and the air inside the housing (31) at the increased temperature can evaporate one or more of the solvent and non-solvent remaining in the polymer. Preferably, the dryer (30) can evaporate the non-solvent supplied together with the precipitated polymer.

[0064] At this time, the heat source can directly heat the housing (31) or supply heated air into the housing (31).

[0065] A dryer (30) according to another embodiment may include a housing (31), a heating unit (32), and a heat source supply unit (33). The heating unit (32) includes an internal space through which a heat source can flow and may be provided in the form of a flow path, a pipe, a cylinder, etc. The heating unit (32) is provided to be in contact with the outer wall of the housing (31) and to surround the outer surface of the housing (31), so that heat from the heating unit (32) is conducted to the housing (31) and the temperature of the air inside the housing (31) can be heated.

[0066] The heat source supply unit (33) can supply heated air into the heating unit (32) or heat the heating unit (32) to heat the air inside the heating unit (32).

[0067] A dryer (30) according to another embodiment may be provided in a combined form of all the above embodiments.

[0068] The heat source and heat source supply unit (33) may include IR (Infrared Ray), microwave, hot air, etc.

[0069] The dryer (30) may include one or more flow paths (34) for discharging the dried polymer to a measuring device (40) and receiving the polymer after measurement is complete. Additionally, the flow path (34) may be equipped with a control valve (35) for controlling the movement of the polymer.

[0070] In one embodiment, the flow path (34) can move the polymer in both directions. That is, a single flow path (34) can perform both the discharge and supply of the polymer. Also, the dryer (30) according to the present invention may include a plurality of flow paths (34) according to one embodiment.

[0071] When sampling a polymer from a dryer (30) to a measuring device (40), the control valve (35) opens the flow path (34), and the polymer can move from the dryer (30) toward the measuring device (40). While measuring the residual non-solvent concentration of the polymer, the control valve (35) can close the flow path. Then, after measuring the residual non-solvent concentration of the polymer at the measuring device (40), the control valve (35) opens the flow path (34), and the polymer sample can move from the measuring device (40) toward the dryer (30) through the flow path (34).

[0072] In another embodiment, the flow path (34) may include a supply flow path (34) through which a polymer is transferred from a dryer (30) to a measuring instrument (40) and a discharge flow path (34) through which a polymer sample is discharged from the measuring instrument to the dryer.

[0073] The supply path (34) and the discharge path (34) may each include a supply valve (35) and a discharge valve (35) that control the supply of polymer and the discharge of polymer samples.

[0074] When sampling a polymer from a dryer (30) to a measuring device (40), the supply valve (35) can open the supply channel (34), and the discharge valve (35) can close the discharge channel (34). Then, when discharging the polymer from the measuring device (40) to the dryer (30) after measurement, the supply valve (35) can close the supply channel (34), and the discharge valve (35) can open the discharge channel (34).

[0075] The measuring device (40) samples the dried polymer and measures the color of the polymer sample to display the color of the polymer sample as a numerical value.

[0076] The measuring device (40) can receive a small amount of polymer from the dryer (30). The waste plastic treatment system (100) according to the present invention can control the drying conditions of the dryer (30) by measuring the color of a small amount of polymer and determining whether there is any non-solvent residue of the entire polymer in the dryer (30) through the color of the small amount of polymer sample.

[0077] The chromaticity value measured by the measuring instrument (40) can be selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space, at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space, at least one of the R value, G value, and B value of the RGB color space, and combinations thereof.

[0078] Preferably, the chromaticity value measured by the measuring instrument (40) can be selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space and a combination thereof.

[0079] The measuring instrument (40) can store CIE Lab color space values ​​and display the color of the measured polymer numerically using the stored CIE Lab color space values. Alternatively, the measuring instrument (40) can receive CIE Lab color space values ​​from an external database.

[0080] FIG. 5 is a drawing illustrating a measuring instrument according to one embodiment of the present invention. In one embodiment, the measuring instrument (40) may include a bezel (41) for storing a polymer sample, a light irradiation unit (42) for irradiating light onto a polymer sample, and a sensor (43) for measuring the color of the polymer sample.

[0081] The bezel (41) may include a stand (44) for mounting a polymer sample. A light irradiation unit (42) is located inside the bezel (41) and can irradiate light in a straight line or diagonally onto the polymer sample mounted on the stand (44). A sensor (43) receives light reflected from the polymer sample and measures the color of the polymer sample.

[0082] The sensor (42) can store CIE Lab color space values ​​and can display the color of the polymer numerically using the stored CIE Lab color space values. For example, the sensor (42) may include a colorimeter.

[0083] The measuring instrument (40) according to the present invention can store data regarding CIE Lab color space values ​​and residual solvent concentration. Accordingly, the measuring instrument (40) can calculate the residual solvent concentration by measuring the CIE Lab color space values ​​of a polymer sample and comparing them with the stored data.

[0084] For example, if the CIE Lab color space values ​​of the polymer sample are L* 70 and a* 0, the residual solvent concentration may be 1,000 to 1,500 ppm.

[0085] The controller (50) can control the drying conditions of the dryer (30) by comparing the polymer color value, which is measured by the measuring instrument (40) and displayed as a numerical value, with a reference value. The reference value may include one or more of L*, a*, and b*, and preferably, the reference value may include the L* value. Since the polymer does not change significantly in the a* and b* values ​​depending on the presence or absence of non-solvent residue, it is preferable to set the reference value to the L* value.

[0086] The controller (50) may store reference values ​​or receive data regarding reference values ​​from an external database. Here, the reference values ​​may include non-solvent concentrations based on environmental reference values ​​and L*a*b* values ​​of polymers that do not contain non-solvents.

[0087] For example, when the polymer recycled through the waste plastic treatment system (100) according to the present invention is PVC, the L*a*b* values ​​of the PVC polymer sample measured by the measuring instrument (40) are L* 73, a* -2, and b* 3.3. And, when the L*a*b* reference value stored in the controller (50) or transmitted to the controller (50) from the outside is L* 70, the controller (50) determines that non-solvent remains in the PVC polymer sample and can increase the drying temperature, drying time, and vacuum level of the dryer (30).

[0088] If the L*a*b* values ​​of the PVC polymer sample measured by the measuring instrument (40) are L* 64, a* -2, and b* 3.3, the controller (50) determines that no non-solvent remains in the PVC polymer sample and can maintain the drying process conditions of the dryer (30) or stop the polymer drying.

[0090] The waste plastic treatment process includes a melting step (S10), a precipitation step (S20), a drying step (S30), a measurement step (S40), and a control step (S50).

[0091] The dissolution step (S10) is a step of dissolving the polymer contained in the waste plastic by stirring the solvent and the waste plastic. In the dissolution step (S10), the solubility of the polymer in the solvent can be controlled by the amount of solvent, temperature, size of the waste plastic, stirring speed, etc.

[0092] In the dissolution step (S10), the solvent may be supplied to the dissolution reactor in such a way that the waste plastic is submerged in the solvent. In one embodiment, in the dissolution step (S10), the solvent and waste plastic may be supplied to the dissolution reactor in a mass ratio of 1:1 to 2:1.

[0093] The dissolution step (S10) can increase the solubility of the polymer by increasing the temperature of the solvent. The temperature of the solvent may be 25°C to 100°C. The dissolution step (S10) may include a step of heating the solvent.

[0094] The melting step (S10) may include a crushing step for crushing waste plastic. The crushing step may increase the surface area of ​​the waste plastic by crushing it, thereby increasing the contact area with the solvent. The size of the crushed waste plastic may be 5 mm to 15 mm. Here, the size of the waste plastic refers to the straight-line distance between the two ends of a single piece of waste plastic in the form of crushed particles.

[0095] The dissolution step (S10) can control the solubility of the polymer by controlling the rotation speed of the solvent. In the dissolution step (S10), as the stirrer rotates, the solvent flows and the solvent and waste plastic can be stirred. The dissolution step (S10) can be stirred under conditions of 100 rpm to 1,500 rpm.

[0096] The precipitation step (S20) is a step of precipitating the polymer by supplying a solution in which the polymer is dissolved to a container in which a non-solvent is stored. The precipitation step (S20) is a step in which the solution in which the polymer is dissolved comes into contact with the non-solvent, and the polymer dissolved in the solution is precipitated.

[0097] In the precipitation step (S20), the size of the polymer can be determined according to the size of the solution falling. In one embodiment, the size of the solution and the size of the polymer may be 1 μm to 1 mm.

[0098] The drying step (S30) is a step of drying the precipitated polymer to remove the nonsolvent remaining in the polymer. The drying step (S30) may receive the polymer precipitated in the precipitation step (S20), at which time the polymer may be separated from the nonsolvent and supplied to a dryer. When separating the polymer and the nonsolvent, a certain amount of the nonsolvent may be contained on the surface of the polymer. The drying step (S30) is a step of removing the nonsolvent remaining on the surface of the polymer by evaporating it.

[0099] The drying step (S30) can reduce the moisture content of the polymer by supplying a heat source to the polymer. The drying step (S30) can reduce the moisture content of the polymer to 30% or less. The drying step (S30) can evaporate the non-solvent by heating the polymer to 30°C to 100°C.

[0100] The measurement step (S40) is a step of preparing a polymer sample by sampling the dried polymer, and measuring the color intensity of the polymer sample to calculate the presence or absence of residual nonsolvent in the polymer sample or the concentration of the nonsolvent contained in the polymer sample. Here, sampling means separating / storing a small amount of the polymer dried in a dryer.

[0101] The chromaticity value measured in the measurement step (S40) may be selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space, at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space, at least one of the R value, G value, and B value of the RGB color space, and combinations thereof.

[0102] Preferably, the measurement step (S40) can quantify the color of the polymer using the CIE Lab color space value of the polymer.

[0103] The measurement step (S50) can sense the reflected light of the polymer sample and display the color of the polymer sample as an L*a*b* value.

[0104] The measurement step (S50) may further include a step of calculating the amount or concentration of nonsolvent remaining in the polymer using the measured L*a*b* values.

[0105] The control step (S60) is a step of controlling the drying conditions of the polymer by comparing the color of the measured polymer sample or the concentration of the non-solvent with a reference value.

[0106] Here, the reference values ​​include the color, non-solvent concentration, and non-solvent amount of a polymer in which all non-solvent has been removed according to dissolution conditions, precipitation conditions, drying conditions, and polymer type through repetitive experiments, or a polymer containing a residual amount based on environmental reference values.

[0107] Therefore, the reference value is made identical to the polymer precipitated according to the present invention, as well as the dissolution and precipitation conditions, while the drying conditions may differ.

[0108] The control step (S60) can compare the color of the polymer sample measured in the measurement step (S50), i.e., the CIE Lab color space value of the polymer sample, with a reference value, or compare the concentration of the residual nonsolvent calculated in the measurement step (S50) with a reference value.

[0109] If the color of the measured polymer sample or the concentration of the calculated residual nonsolvent exceeds a reference value, the control step (S60) determines that the polymer sample and the polymer contained in the dryer contain a nonsolvent greater than the environmental reference value and can increase one or more of the drying temperature, drying time, and vacuum level inside the dryer.

[0110] Alternatively, the control step (S60) may maintain drying conditions by determining that the polymer contains a nonsolvent less than or equal to the environmental standard value if the color of the measured polymer sample or the calculated residual nonsolvent concentration is equal to or less than the standard value.

[0112] The description of the waste plastic treatment process may cite the description of the redundant components within the waste plastic treatment system.

[0114] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0115] 100: Waste Plastic Treatment System 10: Dissolution reactor 11: Main body 12: Stirrer 20: Precipitation reactor 21: Reactor body 22: Dissolved material supply unit 30: Dryer 31: Housing 32: Heating part 33: Heat source supply unit 34: Euro 35: Control valve 40: Measuring instrument 41: Bezel 42: Light Irradiation Department 43: Sensor 44: Stand 50: Controller

Claims

Claim 1 A waste plastic processing system comprising: a dissolution reactor that dissolves a polymer contained in the waste plastic by stirring a solvent and waste plastic; a precipitator that precipitates the polymer by supplying a solution in which the polymer is dissolved to a container in which a non-solvent is stored; a dryer that receives the precipitated polymer and removes one or more of the solvent and the non-solvent contained in the polymer; a measuring instrument that samples the dried polymer and measures the color of the polymer sample; and a controller that controls the drying conditions of the dryer by comparing the color of the polymer sample measured by the measuring instrument with a reference value. Claim 2 A waste plastic processing system according to claim 1, wherein the measuring device comprises a bezel for storing the polymer sample, a light irradiation unit for irradiating light onto the polymer sample, and a sensor for measuring the color intensity of the polymer sample. Claim 3 A waste plastic treatment system according to claim 1, comprising one or more flow paths through which the polymer moves, connecting the dryer and the measuring instrument. Claim 4 A waste plastic treatment system according to claim 3, wherein the flow path comprises a supply path through which the polymer is transferred from the dryer to the measuring instrument and a discharge path through which the polymer is discharged from the measuring instrument to the dryer. Claim 5 A waste plastic treatment system according to claim 3, wherein the flow path is a single flow path that supplies the polymer to the measuring instrument and discharges the polymer from the measuring instrument. Claim 6 A waste plastic processing system according to claim 1, wherein the chromaticity value measured by the measuring instrument is selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space; at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space; at least one of the R value, G value, and B value of the RGB color space; and a combination thereof. Claim 7 A waste plastic treatment process comprising: a dissolution step of stirring a solvent and waste plastic to dissolve a polymer contained in the waste plastic; a precipitation step of supplying the solution in which the polymer is dissolved to a container in which a non-solvent is stored to precipitate the polymer; a drying step of drying the precipitated polymer to remove the non-solvent remaining in the polymer; a measurement step of sampling the dried polymer to prepare a polymer sample and measuring the color of the polymer sample; and a control step of controlling the drying conditions of the polymer by comparing the measured color of the polymer sample with a reference value. Claim 8 A waste plastic treatment process according to claim 7, wherein the control step increases one or more of the drying temperature and drying time of the polymer when the measured color of the polymer sample exceeds the reference value. Claim 9 A waste plastic treatment process according to claim 7, wherein the control step maintains the drying conditions of the polymer when the color intensity of the measured polymer sample is equal to or less than the reference value. Claim 10 A waste plastic treatment process according to claim 7, wherein the chromaticity value measured in the measurement step is selected from at least one of the L* value, a* value, and b* value of the CIE Lab color space; at least one of the X value, Y value, and Z value of the CIE 1931 XYZ color space; at least one of the R value, G value, and B value of the RGB color space; and a combination thereof.

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