Method for producing recycled resin, apparatus for producing recycled resin, and program

Abstract

To provide a method for producing a recycled resin, which can obtain the recycled resin having a predetermined viscosity from a recovered resin while suppressing an addition of unnecessary impurities.SOLUTION: A method for producing a recycled resin includes: a first kneading step of kneading a recovered resin with a first kneader; a measuring step of measuring a viscosity of the recovered resin kneaded by the first kneader; and a second kneading step of kneading the kneaded recovered resin with an additive resin having a melt flow rate (MFR) of 0.1 g / 10 min or more and 100 g / 10 min or less, as measured in accordance with ASTM D1238:2013, in a second kneader to obtain a recycled resin. A ratio of the recovered resin and the additive resin kneaded in the second kneading step is changed depending on the viscosity of the recovered resin measured in the measuring step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing recycled resin, an apparatus for producing recycled resin, and a program.

Background Art

[0002] Various methods have been studied to recover resin components that are not put into actual use, such as resin components (consumer materials) recovered from waste products and resin components (off-grade materials) that do not meet the standards of marketable products inevitably produced in the manufacturing process, and process them so that they can be reused. (Hereinafter, the above-mentioned recovered resin components are also simply referred to as "recovered resin", and the resin components obtained by processing the recovered resin into a form for reuse are also simply referred to as "recycled resin".).

[0003] For example, Patent Document 1 describes a granulator having an extruder that melts and kneads waste plastic materials and extrudes them, and a molding device that granulates the molten plastic extruded by the extruder into pellets.

[0004] According to Patent Document 1, waste plastics to be reused have different melt flow rates (MFRs) depending on their forms and physical properties, and it was difficult to granulate them into pellets having a predetermined MFR. To solve the above problems, in Patent Document 1, a peroxide is added to reduce the molecular weight of a polymer resin such as polyolefin. Specifically, the granulator described in Patent Document 1 has a first extruder into which waste plastic is introduced and kneaded, and a second extruder installed downstream of the first extruder and configured to introduce a peroxide into the molten plastic extruded from the first extruder. Then, the granulator measures the MFR of the molten plastic extruded from the first extruder inline, and adjusts the input amount of the peroxide input by the second extruder based on the measured MFR of the molten plastic, so that it is said that pellets having a predetermined MFR can be granulated.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 2019-65092 Summary of the Invention Problems to be Solved by the Invention

[0006] According to the granulator described in Patent Document 1, it is expected that pellets having a predetermined MFR and viscosity can be obtained from waste plastic. However, the peroxide introduced by the second extruder in the granulator described in Patent Document 1 may also remain in the granulated pellets. These peroxides become impurities in the pelletized resin and may change the physical properties of the resin.

[0007] In view of the above problems, an object of the present invention is to provide a method for producing a recycled resin capable of obtaining a recycled resin having a predetermined viscosity from a recovered resin while suppressing the addition of unnecessary impurities, a kneading apparatus that can be used in the method, and a program that can implement the method. Means for Solving the Problems

[0008] One aspect of the present invention for solving the above problems relates to a method for producing a recycled resin according to the following [1] to

[10] . [1] A first kneading step of kneading a recovered resin in a first kneading machine, A measuring step of measuring the viscosity of the recovered resin kneaded in the first kneading machine, A second kneading step of kneading, in a second kneading machine, the kneaded recovered resin and an additive resin having a melt flow rate (MFR) measured in accordance with ASTM D1238:2013 of 0.1 g / 10 min or more and 100 g / 10 min or less to obtain a recycled resin, The ratio of the recovered resin to the additive resin kneaded in the second kneading step is changed according to the viscosity of the recovered resin measured in the measuring step, A method for producing a recycled resin. [2] In the second kneading step, one type of the additive resin is charged into the second kneader. The method for producing a recycled resin according to [1]. [3] In the first kneading step, the amount of the recovered resin charged into the first kneader is changed according to the viscosity of the recovered resin measured in the measurement step. The method for producing a recycled resin according to [1] or [2]. [4] In the second kneading step, the stirring conditions of the recovered resin and the additive resin are changed according to the viscosity of the recovered resin measured in the measurement step. The method for producing a recycled resin according to any one of [1] to [3]. [5] In the second kneading step, the second kneader adjusts the flow rate of the recycled resin extruded from the second kneader. The method for producing a recycled resin according to any one of [1] to [4]. [6] In the second kneading step, an additive according to the properties required for the recycled resin is charged into the second kneader. The method for producing a recycled resin according to any one of [1] to [5]. [7] In the second kneading step, the recovered resin and the additive resin are kneaded for 3 minutes or more and 30 minutes or less. The method for producing a recycled resin according to any one of [1] to [6]. [8] The recovered resin contains at least one resin selected from the group consisting of polyethylene, polypropylene, polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, polycarbonate, and polyester. The method for producing a recycled resin according to any one of [1] to [7]. [9] The amount of the recovered resin kneaded in the first kneading step is 10% by volume or more and 70% by volume or less based on the total volume of the obtained recycled resin. The method for producing a recycled resin according to any one of [1] to [8].

[10] A step of calculating the ratio of the amount of the recovered resin kneaded in the first kneading step to the total volume of the obtained recycled resin is included. The method for producing a recycled resin according to any one of [1] to [9].

[0009] Another aspect of the present invention for solving the above problems relates to an apparatus for producing a recycled resin according to the following

[11] to

[19] .

[11] A first kneader having a first cylinder for kneading a recovered resin, A viscometer for measuring the viscosity of the recovered resin kneaded by the first kneader, A second kneader having a second cylinder for producing a recycled resin by kneading the kneaded recovered resin and an additive resin having a melt flow rate (MFR) measured in accordance with ASTM D1238:2013 of 0.1 g / 10 min or more and 100 g / 10 min or less, Changing the ratio of the recovered resin and the additive resin kneaded in the second kneading step according to the viscosity of the recovered resin measured in the measuring step, An apparatus for producing a recycled resin.

[12] The second kneader feeds one type of the additive resin into the second cylinder, The apparatus for producing a recycled resin according to

[11] .

[13] The first kneader changes the amount of the recovered resin fed into the first cylinder according to the viscosity of the recovered resin measured by the viscometer, The apparatus for producing a recycled resin according to

[11] or

[12] .

[14] The second kneader changes the stirring conditions of the recovered resin according to the viscosity of the recovered resin measured by the viscometer, The apparatus for producing a recycled resin according to any one of

[11] to

[13] .

[15] The second kneader has a flow rate adjustment mechanism, The flow rate adjustment mechanism adjusts the flow rate of the recycled resin extruded from the second kneader, The apparatus for producing a recycled resin according to any one of

[11] to

[14] .

[16] The second kneader feeds an additive according to the properties required for the recycled resin into the second cylinder The apparatus for producing a recycled resin according to any one of

[11] to

[15] .

[17] The first kneader has a storage unit for storing the recycled resin to be charged into the first cylinder. The storage unit has a stirrer for stirring the recycled resin stored in the storage unit. The apparatus for producing recycled resin according to any one of

[11] to

[16] .

[18] The storage unit has a volume larger than the volume of the first cylinder. The apparatus for producing recycled resin according to

[17] .

[19] The storage unit has a volume 5 times or more larger than the volume of the first cylinder. The apparatus for producing recycled resin according to

[17] or

[18] .

[0010] Another aspect of the present invention for solving the above problems relates to the programs of

[20] to

[21] below.

[20] In an apparatus for producing recycled resin that kneads a molten-kneaded recycled resin and an additive resin to produce a recycled resin, a computer that determines the addition amounts of the recycled resin and the additive resin, receives information regarding the viscosity of the kneaded recycled resin, and determines the addition amounts of the recycled resin and the additive resin such that the viscosity of the recycled resin becomes a target viscosity according to the received information regarding the viscosity. A program for causing execution.

[21] Receiving information regarding the state of the recycled resin before being melt-kneaded, receiving information regarding the quality of the produced recycled resin, generating, by machine learning, an estimation model for estimating the quality of the recycled resin using the received state of the recycled resin and the received viscosity as teacher data, and executing. The program according to

[20] .

Advantages of the Invention

[0011] According to the present invention, there are provided a method for producing a recycled resin capable of obtaining a recycled resin having a predetermined viscosity from a recovered resin while suppressing the addition of unnecessary impurities, a production apparatus for the recycled resin that can be used in the method, and a program capable of implementing the method.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Hereinafter, a kneading apparatus of the present invention will be described with reference to a plurality of embodiments.

[0014] 1. First Embodiment FIG. 1 is a flowchart of a method for producing a recycled resin according to a first embodiment of the present invention.

[0015] The method for producing a recycled resin shown in FIG. 1 includes a step of charging a recovered resin into a first kneader (first step: step S110), a step of performing first kneading in the first kneader (second step: step S120), a step of measuring the viscosity η1 of the recovered resin melted by kneading (third step: step S130), a step of determining the charging amount of the additive resin based on the measured viscosity η1 (fourth step: step S140), a step of controlling the flow rate of the recycled resin (fifth - 1 step: step S150), a step of charging the additive resin into a second kneader (sixth step: step S160), a step of performing second kneading in the second kneader (seventh step: step S170), and a step of pelletizing the recycled resin obtained by the second kneading (eighth step: step S180).

[0016] Note that the viscosities of the recovered resin and the added resin in this specification are the ratio of shear stress to shear rate. The melt viscosity of the resin has temperature dependence and shear rate dependence. The viscosity of the recycled resin may be a value measured by an in-line viscometer of a kneader, for example, or a viscosity measurement value of the recycled resin sampled offline. As the in-line viscometer, a commercially available viscometer (rotational viscometer or capillary viscometer) can be used.

[0017] In the following description, first, the kneading device used in this embodiment will be described, and then, together with the operation of the kneading device, each of the above steps will be described.

[0018] 1-1. Kneading device FIG. 2 is a schematic diagram showing the configuration of a kneading device 100 (a recycled resin production device) according to the first embodiment of the present invention. FIG. 3 is a block diagram showing the main functional configuration of the kneading device. The kneading device 100 is a kneading device for melting and kneading the recovered resin and recycling it into a recycled resin having a predetermined viscosity.

[0019] The recovered resin is typically a resin component recovered from waste products, a resin component that is inevitably produced in the manufacturing process but does not become a final product, and the like. These recovered resins contain various resin types in different ratios, contain metals other than the resin, or contain additives such as pigments and release agents. After being crushed, the recovered resin is subjected to removal of metal components such as iron by magnetic separation or the like, and separated for each resin type by specific gravity separation. However, it is almost impossible to completely separate each component even by these treatments.

[0020] The kneading device 100 is a tandem extruder having a first kneader 110, a second kneader 120 connected to the downstream side of the first kneader 110, and a pelletizer 170 connected to the downstream side of the first kneader 110. The first kneader 110 is provided with a thermometer 135 for measuring the temperature of the resin when measuring the viscosity, and a viscometer 130 for in-line measuring the viscosity of the recovered resin kneaded by the first kneader 110. Further, the kneading device 100 has a control unit 150 that controls the operations of the first kneader 110, the second kneader 120, and the pelletizer 170 based on the viscosity of the recovered resin measured by the viscometer 130.

[0021] The first kneader 110 is a kneader (extruder) for melt-kneading the recovered resin.

[0022] The first kneader 110 includes a long cylindrical cylinder 112 (first cylinder), a screw 114 rotatably disposed in the inner bore of the cylinder 112, a hopper 116 for introducing the recovered resin into the cylinder 112, and an extrusion section 118 for extruding the kneaded recovered resin. Note that the first kneader may have a measuring section 180 for measuring the properties of the recovered resin stored in the storage section 116a (see the second embodiment).

[0023] The cylinder 112 is a container for kneading the recovered resin introduced therein with the screw 114. The cylinder 112 may have a heating section for adjusting the internal temperature to melt the recovered resin.

[0024] One or more screws 114 are disposed inside the cylinder 112 and are rotated by a motor (not shown) to knead the recovered resin in the cylinder 112. A twin-screw extruder composed of two screws can adjust the kneading characteristics as a combination of screw segments having various kneading characteristics such as forward flight, kneading, and reverse flight, and thus can be appropriately selected according to the type of resin and its physical properties. Further, an extruder composed of a plurality of screw shafts can also be appropriately selected according to the kneading performance.

[0025] The ratio (L / D) of the length (L) to the diameter (D) of the screw 114 is preferably 20 or more and 80 or less, more preferably 25 or more and 70 or less, and even more preferably 30 or more and 50 or less. By setting L / D to 20 or more, three types of resins can be sufficiently melted and kneaded. By setting L / D to 80 or less, an excessive increase in the resin temperature can be suppressed, and the power consumption can be reduced.

[0026] The hopper 116 is an inlet for charging the recycled resin into the inside of the cylinder 112. The hopper 116 has a storage part 116a which is a container for temporarily storing the recycled resin to be charged into the first kneader 110 before charging. The storage part 116a has a stirrer 116b inside the container, and the recycled resin stored by the stirrer 116b can be stirred.

[0027] The stirrer 116b can be a dry blender such as a tumble mixer, a V-blender, a ribbon blender, a two-roll mixer, a shaker, or a buffer tank having a rotating blade inside.

[0028] Alternatively, from the viewpoint of making the fluctuations in the viscosity and properties of the recycled resin charged from the storage part 116a into the cylinder 112 smaller by making the volume of the storage part 116a larger, the volume of the storage part 116a is preferably larger than the capacity of the cylinder 112. For example, the volume of the storage part 116a is preferably 3 times or more the capacity of the cylinder 112, and more preferably 5 times or more the capacity of the cylinder.

[0029] The filtration part 117 filters the kneaded resin composition. The filtration part 117 can remove foreign matters such as soil and sand contained in the recycled resin and suppress the mixing of foreign matters into the recycled resin. The filtration part 117 can be a known filter.

[0030] The extrusion section 118 communicates with one end of the resin flow path 140, and extrudes the recycled resin that has been introduced into the interior of the cylinder 112 and melt-kneaded by the rotation of the screw 114 into the resin flow path 140 that communicates with the second kneader 120. The extrusion section 118 can be a known gear pump or the like.

[0031] The resin flow path 140 is a flow path through which the recycled resin extruded from the extrusion section 118 flows while in a molten state. A viscometer 130 is provided in the resin flow path 140. Note that the resin flow path 140 may have a heating section for adjusting the temperature inside the flow path and flowing the recycled resin.

[0032] Needless to say, the configuration of the kneading device 100 is not limited to this. For example, the recycled resin kneaded in the cylinder 112 of the first kneader 110 and passed through the filtration section 117 may pass through the die, viscometer 130, static mixer, gear pump, screen changer, and extruder in this order, or the recycled resin kneaded in the cylinder 112 of the first kneader 110 and passed through the filtration section 117 may pass through the die, viscometer 130, gear pump, screen changer, and extruder in this order. As in the first example, a static mixer may be installed immediately before the viscometer 130. If a static mixer that has the effect of exchanging the positions of the wall surface and the center of the pipe is installed immediately before the viscometer 130, it is considered that the influence of the recycled resin melted and kneaded in the first kneader 110 staying on the inner wall surface of the conduit to which it is connected is minimized, and the stability of the measured viscosity value is improved.

[0033] The second kneader 120 is a kneader (extruder) for adding another resin (hereinafter simply referred to as "additive resin") to the recycled resin kneaded in the first kneader 110 and further melt-kneading to obtain recycled resin.

[0034] Specifically, the second kneader 120 includes a long cylindrical cylinder 122 (second cylinder), a screw 124 rotatably disposed in the inner hole of the cylinder 122, an inlet 126a for introducing the recycled resin melt-kneaded by the first kneader 110 into the cylinder 122, a hopper 126b for charging the additive resin into the cylinder 122, a hopper 126c for charging the additive into the cylinder 122, and an extrusion part 128 for extruding the kneaded recycled resin.

[0035] The cylinder 122 is a container for kneading the resin components introduced therein with the screw 124. The cylinder 122 may have a heating part for adjusting the internal temperature to melt the resin components.

[0036] One or more screws 124 are arranged inside the cylinder 122 and rotated by a motor (not shown) to knead the resin components in the cylinder 122. A twin-screw extruder composed of two screws can adjust the kneading characteristics as a combination of screw segments with various kneading characteristics such as forward flight, kneading, and reverse flight, and thus can be appropriately selected according to the type of resin and its physical properties. Furthermore, an extruder composed of a plurality of screw shafts can also be appropriately selected according to the kneading performance.

[0037] The ratio (L / D) of the length (L) to the diameter (D) of the screw 124 is preferably 20 or more and 80 or less, more preferably 25 or more and 70 or less, and even more preferably 30 or more and 50 or less. By setting L / D to 20 or more, the three types of resins can be sufficiently melted and kneaded. By setting L / D to 80 or less, an excessive rise in the resin temperature can be suppressed, and the power consumption can be reduced.

[0038] The inlet 126a communicates with the other end of the resin flow path 140, and introduces the recycled resin melt-kneaded by the first kneader 110 and extruded from the extrusion part 118 from the resin flow path 140 into the interior of the cylinder 122 of the second kneader 120.

[0039] Hopper 126b is an inlet for introducing the additive resin into the interior of cylinder 122. The additive resin is a resin with a known viscosity, and it is a resin for adjusting the viscosity of the recycled resin to a predetermined range by being added to and mixed with the recycled resin. The additive resin may be the same type of resin as the recycled resin or a different type of resin from the recycled resin.

[0040] Hopper 126b varies the input amount of the additive resin according to the viscosity of the recycled resin measured by viscometer 130. Control for varying the input amount of the additive resin from Hopper 126b will be described later.

[0041] Hopper 126c is an inlet for introducing additives such as crosslinking agents, peroxides, chain extenders, colorants, deodorants, fragrances, stabilizers, antioxidants, crystal nucleating agents, and fillers such as rubber, talc, and calcium carbonate into cylinder 122. Also, reinforcing fiber materials such as glass fiber, carbon fiber, and organic fiber can be added. The addition of these fillers and reinforcing fibers greatly affects the viscosity, but the viscosity of the resin during addition is uniformly controlled, and even when a certain amount of filler and reinforcing fiber is added, the change in viscosity due to the addition is within a range that can be predicted by theoretical formulas, empirical formulas, etc. Therefore, the input of these additives does not make the viscosity of the resulting recycled resin unpredictable.

[0042] The extrusion section 128 has a die, etc., and extrudes the recycled resin having a predetermined viscosity that has been melt-kneaded by the first kneader 110 and the second kneader 120.

[0043] The viscometer 130 is an in-line viscometer that measures the viscosity of the recycled resin melt-kneaded by the first kneader. The viscometer 130 may be any known viscometer that takes out a part of the recycled resin melt-kneaded by the first kneader 110 and moves it to the second kneader to measure its viscosity. For example, devices for measuring viscosity in-line are introduced in R. Gendron, L. E. Daigneault, J. Cell. Plast., 35, 221 (1999) and M. Lee, C. B. Park, C. Tzoganakis, Polym. Eng. Sci., 39, 99 (1999).

[0044] The resin flow path 140 is a flow path that connects the first kneader 110 and the second kneader 120 and has a diameter and structure through which the recycled resin melt-kneaded by the first kneader 110 can flow. The resin flow path 140 may have a valve (not shown) for controlling the movement of the melt-kneaded recycled resin from the first kneader 110 to the second kneader 120. Further, the resin flow path 140 may have a heating section (not shown) for heating the recycled resin moving inside to maintain its fluidity. Also, a viscometer having a viscometer measuring pipe described in Japanese Patent Application No. 2022-075959 by the present inventor may be used.

[0045] The thermometer 135 is disposed at the same position as the viscometer 130 and measures the temperature of the resin when measuring the viscosity. The thermometer 135 may be any known thermometer.

[0046] The pelletizer 170 can be a pelletizer of a known method such as a strand cut type, a watering hot cut type, and an under water cut type.

[0047] In the present embodiment, the hopper 126b changes the input amount of the additive resin according to the viscosity of the recycled resin melt-kneaded by the first kneader 110 measured by the viscometer 130 (in this specification, "viscosity" means melt viscosity).

[0048] The operations of the first kneader 110, the second kneader 120, and the viscometer 130 are controlled by the control unit 150 (see FIG. 3).

[0049] The control unit 150 can be a known computer and includes a CPU 152 (Central Processing Unit), a RAM 154 (Random Access Memory), a ROM 156 (Read Only Memory), and a storage unit 158. The CPU 152 reads out various control programs and setting data stored in the ROM 156, stores them in the RAM 154, and executes the programs to perform various arithmetic processes. Further, the CPU 152 comprehensively controls the overall operation of the kneading device 100 including the first kneader 110, the second kneader 120, and the viscometer 130. The RAM 154 provides a working memory space for the CPU 152 and stores temporary data. Note that the RAM 154 may include a non-volatile memory. The ROM 156 stores various control programs, setting data, etc. executed by the CPU 152. Note that instead of the ROM 156, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used. Jobs input from the outside via the input / output interface 162 and data related to the jobs are stored in the storage unit 158. As the storage unit 158, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) etc. may be used in combination.

[0050] Hereinafter, a method for manufacturing recycled resin according to the present embodiment in the first to eighth steps using the above kneading device 100 will be described.

[0051] 1-2. Feeding of the recovered resin (first step: step S110) In the first step, the hopper 116 feeds the recycled resin into the first kneader 110. Specifically, the hopper 116 feeds a controlled amount of the recycled resin stored in the storage section 116a into the inside of the cylinder 112. Note that, by the control of the cylinder 112 (or the heating section) by the control unit 150, the temperature inside the cylinder 112 in this step is set to the temperature at which the recycled resin melts or becomes fluid.

[0052] At this time, the stirrer 116b can also suppress sudden and non-uniform viscosity fluctuations of the recycled resin to be fed by stirring the recycled resin stored inside the storage section 116a.

[0053] 1-3. First kneading (Second step: Step S120) In the second step, the first kneader 110 kneads the recycled resin that has been fed into the inside of the cylinder 112 and is melting inside the cylinder 112 (first kneading). Specifically, the first kneader 110 rotates the screw 114 at a rotational speed controlled by the control unit 150 to knead the recycled resin and move the kneaded recycled resin in the direction of the outlet of the cylinder 112 (the direction of the extrusion section 118).

[0054] By the above kneading, the recycled resin melts and becomes a fluid state. The recycled resin in the fluid state is extruded from the extrusion section 118. The extruded recycled resin flows through the resin flow path 140 and is sent to the second kneader 120.

[0055] 1-4. Measurement of the viscosity η1 of the recycled resin (Third step: Step S130) In the third step, the viscometer 130 measures the viscosity η1 of the recovered resin flowing through the resin flow path 140. The viscosity measured here is the so-called melt viscosity, which means the melt viscosity measured under the measurement conditions commonly used for the resin being melt-kneaded. However, the measured values of viscosity at other temperatures and shear rates can also be easily converted to the same temperature and the same shear rate by using the relational expressions described later. Therefore, the measurement conditions of the viscosity can be freely set without particular restrictions, or can be linked to the temperature conditions and operation information of the extruder. The viscometer 130 transmits the measured viscosity to the CPU 152. The CPU 152 temporarily stores the viscosity of the resin in the storage unit 158.

[0056] 1-5. Determination of the Input Amount of the Added Resin (Fourth Step: Step S140) In the fourth step, the control unit 150 receives the data indicating the viscosity η1 of the recovered resin measured by the viscometer 130 in the third step, and determines the input amount of the added resin to be input in the sixth step according to the viscosity of the data.

[0057] In this step, based on the theory regarding the blending of polymers, for example, the Double-Reptation theory (C. Tsenoglou, Macromolecules, 24, 1762-1767 (1991)), from the volume of the recovered resin, the viscosity η1 of the obtained recovered resin, and the known viscosity η2 of the added resin, the volume of the added resin to be input into the second kneader to obtain the recycled resin with a viscosity of η Blend is calculated.

[0058] According to the Double-Reptation theory, in a two-component system such as this embodiment, the viscosity η Blend of the mixture of the first resin and the second resin can be expressed by the following formula (1).

[0059]

Equation

[0060] In the formula (1), φ1 represents the volume fraction of the first resin (in this embodiment, the recycled resin) with respect to the total volume of the resin components charged into the second kneader, η1 represents the viscosity of the first resin, φ2 represents the volume fraction of the second resin (in this embodiment, the added resin) with respect to the total volume of the resin components charged into the second kneader, η2 represents the viscosity of the second resin, and η Blend represents the viscosity of the resulting mixture.

[0061] Here, the viscosity η1 of the first resin is the viscosity of the recycled resin kneaded in the first kneader measured by the viscometer 130. Also, the viscosity η2 of the second resin (viscosity of the added resin) is known. In the formula (1), the unknown values are φ1 and φ2. However, in this embodiment, since φ1 + φ2 = 1, φ2 can be read as 1 - φ1. That is, the unknown value in the formula (2) is only φ2.

[0062] Therefore, by substituting these values and the value of the viscosity η Blend of the recycled resin to be obtained into the formula (1), the volume fraction φ2 of the added resin to be charged into the second kneader 120 can be calculated. And the actual volume V1 of the first resin can be obtained from the rotation speed of the gear pump of the extrusion part 128 attached to the first kneader 110. Therefore, the volume V2 of the second resin (added resin) to be charged into the second kneader 120 from the hopper 126b can be calculated by V1×(φ2 / φ1). In this way, the measuring unit changes the input amount of the added resin input in the sixth step according to the viscosity of the recycled resin measured in the fourth step, thereby changing the ratio of the recycled resin and the added resin kneaded in the second kneading (the first to sixth steps). Since the viscosity of the resin depends on the shear rate, a viscosity corresponding to the shear rate condition of the in-line viscosity measurement is selected. As another method, the accuracy of viscosity control can be improved by introducing and expanding models (such as the Cross formula, Bird-Carreau formula, Carreau-Yasuda formula, etc.) representing the shear rate dependence of the resin viscosity into the formula (1).

[0063] Incidentally, the volume fraction φ1 of the recovered resin can be, for example, 0.1 or more and 0.7 or less (10% by volume or more and 70% by volume or less), preferably 0.2 or more and 0.6 or less (20% by volume or more and 60% by volume or less), and more preferably 0.3 or more and 0.5 or less (30% by volume or more and 50% by volume or less).

[0064] 1-6. Control of Flow Rate (Step 5-1: Step S150-1) By the way, the source of the recovered resin is often indefinite, and the viscosity of the recovered resin often changes during the production of the recycled resin. Therefore, if the input amount of the additive resin is changed according to the viscosity of the recovered resin, the flow rate of the recycled resin extruded from the second kneader 120 will also change. When the flow rate changes, the size of the pellets is changed, so it may be necessary to change the size of the pelletizer 170 accordingly.

[0065] In the present embodiment, when the above problems occur, optionally, in Step 1-5, the control unit 150 controls the flow rate extruded from the second kneader 120. The control of the flow rate can be performed by various flow rate adjustment mechanisms. For example, the amount of the recovered resin input from the hopper 116 into the first kneader 110 (cylinder 112) can be changed, the stirring conditions (such as the rotation speed of the screw 114) in the cylinder 112 can be changed, the stirring conditions (such as the rotation speed of the screw 124) in the cylinder 122 can be changed, the flow rate of the recovered resin extruded from the extrusion part 118 can be changed, or the flow rate of the recycled resin extruded from the extrusion part 128 can be changed.

[0066] 1-7. Input of Additive Resin (Step 6: Step S160) In the sixth step, the hopper 126b feeds the additive resin into the second kneader 120. Specifically, the hopper 126b feeds the amount of additive resin determined in the fourth step into the interior of the cylinder 122 under the control of the control unit 150. In this embodiment, the hopper 126b feeds only one type of resin with a constant viscosity into the interior of the cylinder 122. Note that, by the control of the cylinder 122 (or the heating unit) by the control unit 150, the temperature inside the cylinder 122 in this step is set to the temperature at which the recovered resin melts or flows.

[0067] The additive resin may have a melt flow rate (MFR) measured in accordance with ASTM D1238:2013 of 0.1 g / 10 min or more and 100 g / 10 min or less. The MFR of the additive resin can be changed according to the viscosity of the recycled resin to be obtained. The additive resin is preferably the same type of resin as the recycled resin.

[0068] Also, at this time, the hopper 126c feeds the various additives described above into the second kneader 120 (inside the cylinder 122). At this time, in order to adjust the viscosity of the recycled resin, a crosslinking agent, a chain extender, a peroxide, etc. may be added as additives. By these additives, the molecular weight of the recycled resin can be adjusted to further finely adjust the viscosity of the recycled resin or to further increase the viscosity when the increase in viscosity is insufficient with only the additive resin. The feeding of these additives from the hopper 126c is performed under the control of the control unit 150.

[0069] 1-8. Second Kneading (Seventh Step: Step S170) In the seventh step, the second kneader 120 kneads the recovered resin and the additive resin that are fed into the interior of the cylinder 122 and melted inside the cylinder 122 (second kneading). Specifically, the second kneader 120 rotates the screw 124 at a rotation speed controlled by the control unit 150 to knead the recovered resin and move the kneaded recovered resin in the direction of the outlet of the cylinder 122 (the direction of the extrusion part 128).

[0070] Through the above kneading, the recovered resin and the added resin are melt-kneaded at a predetermined ratio according to the viscosity η of the recycled resin to be obtained. Blend The kneaded recovered resin and added resin become the recycled resin and are extruded from the extrusion part 128. The extrusion part 118 extrudes the recycled resin at a controlled flow rate by the control part 150.

[0071] 1-9. Pelletization (Eighth step: Step S180) The extruded recycled resin is cut by the pelletizer 170 to be pelletized and stored in the storage container.

[0072] 2. Second Embodiment FIG. 4 is a flowchart of a method for manufacturing a recycled resin according to the second embodiment of the present invention.

[0073] In this embodiment, after determining the addition amount of the added resin (fourth step), there is a step of determining the type and amount of the additive to be put into the second kneader (fifth-two step: step S150-2). Then, when the added resin is put in (sixth step), the determined type and amount of the additive are put into the second kneader, and in the second kneading (seventh step), the recovered resin, the added resin, and the additive are kneaded.

[0074] The kneading device used in this embodiment can have the same configuration as the kneading device 100 used in the first embodiment. Also, each step other than the fifth-two step can be performed in the same manner as in the first embodiment. Therefore, overlapping explanations are omitted, and the description will focus on the differences.

[0075] 2-1. Determination of Additive (Fifth-two step: step S150-2) Since the source of the recovered resin is often indefinite, during the production of the recycled resin, the degree of contamination, color, smell, etc. of the recovered resin often change. On the other hand, depending on the properties required for the recycled resin, it may be required to produce pellets of the recycled resin having a predetermined appearance and color tone, or it may be required that no smell adheres to the recycled resin.

[0076] In this embodiment, when the above problems occur, optionally in the 5-2 step, the control unit 150 controls the type and amount of the additive to be introduced from the hopper 126c into the cylinder 122 of the second kneader 120. For example, when the contamination of the recycled resin is large or when coloring is required for the recycled resin, the control unit 150 causes a coloring agent to be introduced from the hopper 126c into the cylinder 122. Also, when an odor adheres to the recycled resin, the control unit 150 causes a deodorant or a fragrance to be introduced from the hopper 126c into the cylinder 122.

[0077] Then, in the 6th step, the hopper 126b introduces these additives according to the properties required for the recycled resin into the cylinder 122 of the second kneader 120. The introduced additives are kneaded together with the recycled resin and the additive resin to change the properties of the recycled resin.

[0078] Note that in this embodiment, the first kneader 110 may have a measuring unit 180 that measures the properties of the recycled resin stored in the storage unit 116a (or a measuring unit that measures the properties of the recycled resin before it is collected in the storage unit 116a). The measuring unit 180 can be, for example, a camera that measures the degree of contamination and color tone of the recycled resin, an odor detector that measures the odor of the recycled resin, and the like. Then, the control unit 150 may control the type and amount of the additive to be introduced from the hopper 126c into the cylinder 122 based on the properties of the recycled resin measured by the measuring unit 180.

[0079] Note that here, an aspect of performing the 5-2 step without performing the 5-1 step has been described, but in this embodiment, after performing the flow rate control in the 5-1 step, the determination of the additive in the 5-2 step, the introduction of the additive in the 6th step, and the kneading in the 7th step may further be performed.

[0080] [Other Embodiments] Note that each of the above-described embodiments shows an example of the present invention, and it goes without saying that the present invention is not limited to each of the above-described embodiments, and various other embodiments are possible within the scope of the idea of the present invention.

[0081] For example, in each of the above-described embodiments, the viscosity of the melt-kneaded recycled resin was measured by a viscometer installed downstream of the first kneader. However, the viscometer may be disposed inside the first kneader or in a resin flow path connecting the first kneader and the second kneader. Further, the viscometer may be configured to measure the pressure and flow rate of the recycled resin extruded from the extrusion section of the first kneader and calculate the viscosity of the recycled resin from these values.

[0082] Also, in each of the above-described embodiments, an additive resin that is polyethylene or polypropylene was added to the recycled resin containing polyethylene and polypropylene. However, resin types such as polyethylene alone, polypropylene alone, and polyester alone are not limited to these, and may be off-grade materials or separated and sorted recycled materials. In the present invention, the recycled resin and the additive resin can be a combination of various resins including polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), polycarbonate, polyurethane, and polyester. The polyester may be polylactic acid, polyethylene terephthalate, or the like.

[0083] Also, in each of the above-described embodiments, the recycled resin was added to the first kneader. However, not only the recycled resin but also a virgin material may be added to the first kneader, or a natural resin with an unknown viscosity may be added to the first kneader. Further, as a compatibilizer such as a copolymer of polyethylene and polypropylene, liquid ethylene-propylene rubber, pelletized ethylene-propylene rubber, ethylene-butene rubber, propylene-butene rubber, or propylene-butene-ethylene rubber may be added to the first kneader.

[0084] Also, in each of the above-described embodiments, the extrusion section of the second kneader may extrude the recycled resin into any known shape including a sheet shape, a film shape, a rod shape, a plate shape, a pipe shape, a shaped cross-section molded product, and a strand shape. Alternatively, a known molding machine may be disposed downstream of the extrusion section to mold the extruded recycled resin into a predetermined shape.

[0085] Further, in each of the above-described embodiments, the kneading device may have a second viscometer that measures the viscosity of the molten recycled resin extruded from the second kneader. The second viscometer can be an in-line viscometer similar to the above-described viscometer 130.

[0086] Further, the control unit 150 stores the relationship between the state at the time of collecting the recycled resin (collection source, collection time, storage period, usage period) received from the input / output interface 162, or the characteristics of the recycled resin measured by the measurement unit 180, the viscosity η1 of the recycled resin calculated in the fifth step (step 150b), and generates an estimation model for estimating the viscosity η1 of the recycled resin from the state at the time of collecting the recycled resin by machine learning using these as teacher data. Then, the viscosity η1 of the recycled resin may be output from the state or characteristics at the time of collecting the recycled resin using this estimation model or the above-described estimation model created in advance. Further, the above-described estimation model may be updated by re-learning based on the viscosity η1 of the recycled resin calculated by repeating each of the above steps and the actual viscosity η1 of this recycled resin measured by the viscometer 130.

[0087] Further, the control unit 150 stores the relationship between the state at the time of collecting the recycled resin (collection source, collection time, storage period, usage period) received from the input / output interface 162, or the characteristics of the recycled resin measured by the measurement unit 180, and the quality of the recycled resin determined from the obtained pellets, and generates an estimation model for estimating the quality (viscosity, color tone, smell, etc.) of the recycled resin from the state at the time of collecting the recycled resin by machine learning using these as teacher data. Then, the quality of the recycled resin may be output from the state or characteristics at the time of collecting the recycled resin using this estimation model or the above-described estimation model created in advance. Further, the above-described estimation model may be updated by re-learning based on the quality of the recycled resin calculated by repeating each of the above steps and the actual quality of the recycled resin determined from the obtained pellets.

Industrial Applicability

[0088] According to the kneading device of the present invention, the kneading device of the present invention capable of obtaining a recycled resin having a predetermined viscosity can equalize the viscosity of the recycled resin obtained from consumer materials and off-grade materials, and recycle it into a recycled resin that is easy to use for various applications. Therefore, it is expected to expand the scope of reuse of these resins and contribute to the improvement of resin recycling efficiency.

Explanation of Signs

[0089] 100 Kneading device 110 First kneader 112 Cylinder 114 Screw 116 Hopper 116a Storage part 116b Agitator 117 Filtration part 118 Extrusion part 120 Second kneader 122 Cylinder 124 Screw 126a Inlet 126b Hopper 126c Hopper 128 Extrusion part 130 Viscometer 135 Thermometer 140 Resin flow path 150 Control part 152 CPU 154 RAM 156 ROM 158 Storage part 162 Input / output interface 170 Pelletizer 180 Measuring part

Claims

1. A first kneading step of kneading the recycled resin in a first kneader; A measuring step of measuring the viscosity of the recycled resin kneaded in the first kneader; A second kneading step of kneading, in a second kneader, the kneaded recycled resin and an additive resin having a melt flow rate (MFR) measured in accordance with ASTM D1238:2013 of 0.1 g / 10 min or more and 100 g / 10 min or less to obtain a recycled resin; The ratio of the recycled resin to the additive resin kneaded in the second kneading step is changed according to the viscosity of the recycled resin measured in the measuring step; A method for producing a recycled resin.

2. In the second kneading step, one type of the additive resin is put into the second kneader; The method for producing a recycled resin according to Claim 1.

3. In the first kneading step, the amount of the recycled resin put into the first kneader is changed according to the viscosity of the recycled resin measured in the measuring step; The method for producing a recycled resin according to Claim 1.

4. In the second kneading step, the stirring conditions of the recycled resin and the additive resin are changed according to the viscosity of the recycled resin measured in the measuring step; The method for producing a recycled resin according to Claim 1.

5. In the second kneading step, the second kneader adjusts the flow rate of the recycled resin extruded from the second kneader; The method for producing a recycled resin according to Claim 1.

6. In the second kneading step, an additive according to the properties required for the recycled resin is put into the second kneader The method for producing a recycled resin according to Claim 1.

7. In the second kneading step, the recycled resin and the additive resin are kneaded for 3 minutes or more and 30 minutes or less; The method for producing a recycled resin according to Claim 1.

8. The recycled resin contains at least one resin selected from the group consisting of polyethylene, polypropylene, polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, polycarbonate, and polyester; The method for producing a recycled resin according to Claim 1.

9. The amount of the recycled resin kneaded in the first kneading step is 10% by volume or more and 70% by volume or less based on the total volume of the obtained recycled resin; The method for producing a recycled resin according to Claim 1.

10. A step of calculating a ratio of the amount of the recovered resin kneaded in the first kneading step to the total volume of the obtained recycled resin is included. The method for producing a recycled resin according to claim 1.

11. A first kneader having a first cylinder for kneading a recovered resin; A viscometer for measuring the viscosity of the recovered resin kneaded by the first kneader; A second kneader having a second cylinder for producing a recycled resin by kneading the kneaded recovered resin and an additive resin having a melt flow rate (MFR) measured in accordance with ASTM D1238:2013 of 0.1 g / 10 min or more and 100 g / 10 min or less; The ratio of the recovered resin and the additive resin kneaded by the second kneader is changed according to the viscosity of the recovered resin measured by the viscometer. An apparatus for producing a recycled resin.

12. The second kneader feeds one type of the additive resin into the second cylinder. The apparatus for producing a recycled resin according to claim 11.

13. The first kneader changes the amount of the recovered resin fed into the first cylinder according to the viscosity of the recovered resin measured by the viscometer. The apparatus for producing a recycled resin according to claim 11.

14. The second kneader changes the stirring conditions of the recovered resin according to the viscosity of the recovered resin measured by the viscometer. The apparatus for producing a recycled resin according to claim 11.

15. The second kneader has a flow rate adjusting mechanism. The flow rate adjusting mechanism adjusts the flow rate of the recycled resin extruded from the second kneader. The apparatus for producing a recycled resin according to claim 11.

16. The second kneader feeds an additive according to the properties required for the recycled resin into the second cylinder. The apparatus for producing a recycled resin according to claim 11.

17. The first kneader has a storage section for storing the recovered resin fed into the first cylinder. The storage section has a stirrer for stirring the recovered resin stored in the storage section. The apparatus for producing a recycled resin according to claim 11.

18. The storage section has a volume larger than the capacity of the first cylinder. The apparatus for producing a recycled resin according to claim 17.

19. The storage section has a volume 5 times or more larger than the capacity of the first cylinder. The apparatus for producing a recycled resin according to claim 17.

20. In a production apparatus for a recycled resin that produces a recycled resin by kneading a molten-kneaded recycled resin and an additive resin, a computer that determines the addition amounts of the recycled resin and the additive resin, receives information regarding the viscosity of the kneaded recycled resin; determines the addition amounts of the recycled resin and the additive resin according to the received information regarding the viscosity; A program for causing the computer to execute the above.

21. receives information regarding the state of the recycled resin before being melt-kneaded; receives information regarding the quality of the produced recycled resin; generates, by machine learning, an estimation model that estimates the quality of the recycled resin, using the received state of the recycled resin and the received viscosity as teacher data; Execute the program according to Claim 20.

Images