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

Abstract

The present invention provides a method for producing recycled resin with uniform viscosity through addition of additive resin, the method being capable of being executed even when only one kneading machine is used. The method for producing recycled resin comprises: a process for supplying recovered resin to a kneading machine; a process for supplying two or more types of additive resin with different viscosities to the kneading machine; a process for kneading the recovered resin and the two or more types of additive resin to obtain recycled resin; a process for measuring the viscosity of the resin being kneaded or the recycled resin obtained by kneading after the start of kneading; and a process for changing the supply amount of each of the two or more types of additive resin on the basis of the measured viscosity.

Description

[Technical Field]

[0001] This invention relates to a method for producing recycled resin, an apparatus for producing recycled resin, and a program. [Background technology]

[0002] Various methods are being considered for recovering and processing resin components that are not used in actual production, such as resin components recovered from waste products (consumer materials) and resin components that do not meet the specifications for commercially sold products that are inevitably produced during the manufacturing process (off-grade materials), so that they can be reused (hereinafter, the above-mentioned recovered resin components will also be simply referred to as "recovered resin," and the resin components obtained by processing the recovered resin into a form that can be reused will also be simply referred to as "recycled resin").

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

[0004] According to Patent Document 1, waste plastics intended for reuse have different melt flow rates (MFRs) depending on their form and physical properties, making it difficult to granulate them into pellets with a predetermined MFR. To solve this problem, Patent Document 1 describes adding peroxide to reduce the molecular weight of high-molecular-weight resins such as polyolefins. Specifically, the granulator described in Patent Document 1 includes a first extruder into which waste plastics are fed and kneaded, and a second extruder installed downstream of the first extruder to add peroxide to the molten plastics extruded from the first extruder. The granulator measures the MFR of the molten plastics extruded from the first extruder in-line, and by adjusting the amount of peroxide added by the second extruder based on the measured MFR of the molten plastics, it is possible to granulate pellets with a predetermined MFR.

[0005] In response to this, the present inventors have developed a method, as described in Patent Document 2, to obtain a recycled resin having a desired viscosity by connecting two or more kneaders in tandem and changing the amount of additive resin added in the second kneader according to the viscosity of the recovered resin kneaded in the first kneader. This method makes it possible to obtain a recycled resin having a predetermined viscosity from the recovered resin while suppressing the addition of impurities such as peroxide as described in Patent Document 1. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-065092 [Patent Document 2] Japanese Patent Publication No. 2021-137979 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The method described in Patent Document 2 involves using two or more kneaders, measuring the viscosity of the recovered resin melted in the first kneader, and changing the amount of additive resin added in the second kneader according to the measured viscosity. However, from the viewpoint of saving space and costs, it is desirable that the viscosity of the recycled resin can be made uniform by adding the same amount of additive resin even when using only one kneader.

[0008] In view of the above problems, the present invention aims to provide a method for obtaining a recycled resin with uniform viscosity by adding an additive resin, which can be carried out even when using only one kneader, a recycled resin manufacturing apparatus for carrying out the manufacturing method, and a program for operating the apparatus. [Means for solving the problem]

[0009] A method for producing recycled resin according to one aspect of the present invention for solving the above problems relates to the following [1] to [9]. [1] A process of supplying the recovered resin to a kneader, A step of supplying two or more additive resins with different viscosities to the kneader, A step of kneading the recovered resin and the two or more additive resins to obtain a recycled resin, After the start of the kneading, the step of measuring the viscosity of the kneaded resin or the recycled resin obtained by kneading, A step of changing the supply amount of each of the two or more additive resins based on the measured viscosity, A method for producing recycled resin having the following characteristics. [2] A method for producing recycled resin according to [1], wherein the degree of stirring before supplying the recovered resin is changed based on the measured viscosity. [3] A method for producing recycled resin according to [1] or [2], wherein the kneading time of the recovered resin and the two or more additive resins in the kneader is changed based on the measured viscosity. [4] The step of calculating the viscosity of the supplied recovered resin from the measured viscosity, The step of changing the supply amount is a step of changing the supply amount of each of the two or more additive resins to the supply amount determined based on the viscosity of the recovered resin calculated above. A method for producing recycled resin as described in any of [1] to [3]. [5] The method for producing recycled resin according to any one of [1] to [4], wherein the mixing time between the recovered resin and the two or more additive resins in the kneader is 3 minutes or more and 30 minutes or less. [6] The method for producing a recycled resin according to any one of [1] to [5], wherein the recycled resin comprises at least one resin selected from the group consisting of polyethylene, polypropylene, polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), polycarbonate, and polyester. [7] The two or more additive resins are: A second resin with a smaller melt flow rate, A third resin with a higher melt flow rate, The melt flow rate (MFR) of both the second and third resins, as measured in accordance with ASTM D1238 (2013), is between 1 g / 10 min and 300 g / 10 min. A method for producing recycled resin as described in any of [1] to [6]. [8] The ratio of the melt flow rate of the second resin to the melt flow rate of the third resin (MFR of the second resin / MFR of the third resin), measured under the same conditions, is 2 or more and 100 or less. [7] A method for producing recycled resin as described above. [9] The method for producing recycled resin according to any one of [1] to [8], wherein the amount of the recovered resin supplied is 10% by volume or more and 70% by volume or less of the total volume of the recycled resin.

[0010] Furthermore, a manufacturing apparatus for recycled resin according to another aspect of the present invention for solving the above problems relates to the following

[10] to

[18] .

[10] A cylinder having a screw, A first supply unit that supplies the recovered resin to the cylinder, It has a second supply unit that supplies two or more additive resins with different viscosities to the cylinder, A kneader for kneading the recovered resin and the two or more additive resins inside the cylinder, A viscometer for measuring the viscosity of the resin being kneaded by the aforementioned kneader, or the recycled resin obtained by kneading with the kneader, A control unit that changes the supply amount of each of the two or more additive resins from the second supply unit based on the viscosity measured by the viscometer, A manufacturing apparatus for recycled resin, having the following features.

[11] The first supply unit has a storage unit for storing the recovered resin supplied to the cylinder, The storage unit has a stirrer for stirring the recovered resin.

[10] The apparatus for manufacturing recycled resin.

[12] The apparatus for manufacturing recycled resin according to

[11] , wherein the storage section has a volume larger than the capacity of the cylinder.

[13] The apparatus for manufacturing recycled resin according to

[11] or

[12] , wherein the capacity of the storage section is five times or more the capacity of the cylinder.

[14] The apparatus for producing recycled resin according to any one of

[11] to

[13] , wherein the control unit changes the degree of stirring of the recovered resin by the stirrer based on the viscosity measured by the viscometer.

[15] The apparatus for producing recycled resin according to any one of

[10] to

[14] , wherein the control unit changes the mixing time of the recovered resin and the two or more additive resins inside the cylinder based on the viscosity measured by the viscometer.

[16] The control unit calculates the viscosity of the supplied recovered resin from the measured viscosity, and changes the supply amount of each of the two or more additive resins to the supply amount determined based on the calculated viscosity of the recovered resin, as described in any of

[10] to

[15] .

[17] The control unit calculates the viscosity of the supplied recovered resin from the measured viscosity, and uses the calculated viscosity of the recovered resin and the state of the recovered resin at the time of recovery as training data to generate an estimation model by machine learning that estimates the viscosity of the recovered resin predicted from the state of recovery. A manufacturing apparatus for recycled resin as described in any of

[10] to

[16] .

[18] The apparatus for manufacturing recycled resin according to any one of

[10] to

[17] , wherein the screw has a ratio (L / D) of length (L) to diameter (D) of 20 or more and 80 or less.

[0011] Furthermore, programs relating to another aspect of the present invention for solving the above problems are described in

[19] to

[20] below.

[19] When producing recycled resin by kneading recovered resin with two or more types of additive resins with different viscosities, a computer that determines the supply amount of the two or more types of additive resins is used. The system accepts viscosity data measured from the kneaded resin or the recycled resin obtained by kneading, Based on the amount of the recovered resin used in the production of the resin or recycled resin whose viscosity has been measured, the amount of each of the two or more additive resins, and the viscosity of each of the two or more additive resins, the amount of each of the two or more additive resins to be supplied is determined such that the viscosity of the resin or recycled resin whose viscosity has been measured becomes the target viscosity. A program that executes the command.

[20] When determining the supply quantity, Based on the viscosity data received, the viscosity of the recovered resin is calculated, Based on the viscosity of the recovered resin calculated above, the supply amount of each of the two or more additive resins is determined, The program described in

[19] that causes the computer to execute the program. [Effects of the Invention]

[0012] The present invention provides a method for obtaining a recycled resin with uniform viscosity by adding an additive resin, which can be performed even when using only one kneader, a recycled resin manufacturing apparatus for carrying out the manufacturing method, and a program for operating the apparatus. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a flowchart of a method for producing recycled resin according to a first embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the general configuration of a recycled resin manufacturing apparatus (kneading apparatus) used in the first embodiment of the present invention. [Figure 3] Figure 3 is a block diagram showing the main functional configuration of a recycled resin manufacturing apparatus (kneading apparatus) used in the first embodiment of the present invention. [Figure 4] Figure 4 is a flowchart showing each subprocess in the first to fifth steps (step S150) of the first embodiment of the present invention, in which the control unit changes the supply amount of additive resin. [Figure 5]Figure 5 is a flowchart showing each subprocess in the first to fifth steps (step S150) of the second embodiment of the present invention, in which the control unit changes the supply amount of additive resin. [Figure 6] Figure 6 is a flowchart showing the processing of the control unit in the third embodiment of the present invention. [Figure 7] Figure 7 shows the simulation results in Calculation Example 1. [Figure 8] Figure 8 shows the simulation results in calculation example 2. [Figure 9] Figure 9 shows the simulation results for calculation example 3. [Figure 10] Figure 10 shows the simulation results in calculation example 4. [Figure 11] Figure 11 shows the simulation results in calculation example 5. [Figure 12] Figure 12 shows the simulation results in calculation example 6. [Figure 13] Figure 13 shows the simulation results for calculation example 7. [Figure 14] Figure 14 shows the simulation results for calculation example 8. [Figure 15] Figure 15 shows the simulation results for calculation example 9. [Figure 16] Figure 16 shows the simulation results for calculation example 10. [Figure 17] Figure 17 shows the simulation results in calculation example 11. [Figure 18] Figure 18 shows the simulation results in calculation example 12. [Figure 19] Figure 19 shows the simulation results in calculation example 13. [Modes for carrying out the invention]

[0014] The kneading apparatus of the present invention will be described below with reference to several embodiments.

[0015] In this specification, with respect to numerical ranges described in stages, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages.

[0016] 1. First Embodiment Figure 1 is a flowchart of a method for producing recycled resin according to a first embodiment of the present invention.

[0017] The method for producing recycled resin according to this embodiment includes the steps of supplying recovered resin to a kneader (Step 1-1: Step S110), supplying two or more additive resins with known and different viscosities to the kneader (Step 1-2: Step S120), and kneading the recovered resin with the two or more additive resins to obtain recycled resin (Step 1-3: Step S130).

[0018] In this specification, the viscosity of the recovered resin and the added resin is expressed as the ratio of shear stress to shear rate. The melt viscosity of the resin is temperature-dependent and shear-rate-dependent. The viscosity of the recycled resin may be a value measured, for example, by an in-line viscometer in a kneader, or it may be a viscosity measurement of the recycled resin sampled offline. A commercially available viscometer (rotary viscometer or capillary viscometer) can be used as the in-line viscometer.

[0019] In this embodiment, after the start of kneading, a step of measuring the viscosity of the recycled resin obtained by kneading (steps 1-4: step S140) and a step of changing the supply amount of each of the two or more additive resins based on the measured viscosity (steps 1-5: step S150) are performed. Each of these steps is performed when kneading the recovered resin with the two or more additive resins using a kneading device. Therefore, in the following description, the kneading device used in this embodiment will be described first, and then each of the above steps will be described along with the operation of the kneading device.

[0020] 1-1. Mixing device Figure 2 is a schematic diagram showing the general configuration of the recycled resin manufacturing apparatus (kneading apparatus) used in this embodiment. Figure 3 is a block diagram showing the main functional configuration of the kneading apparatus.

[0021] The kneading device 100 includes a kneader 110, which is a kneader (extruder) for melt-kneading the recovered resin and two or more types of additive resins; a viscometer 120 for measuring the viscosity of the recovered resin kneaded by the kneader 110 in-line; a thermometer 125 for measuring the temperature of the resin when measuring the viscosity; and a control unit 130 that controls the operation of the kneader 110 based on the viscosity of the recovered resin measured by the viscometer 120.

[0022] The kneader 110 includes a long cylindrical cylinder 111, a screw 112 rotatably positioned inside the cylinder 111, a hopper 113 (first supply unit) for supplying recovered resin (hereinafter also referred to as "first resin") into the cylinder 111, a hopper 115 (second supply unit) for supplying two or more types of additive resins (in this embodiment, an example of supplying two types of additive resins is shown, and hereinafter these additive resins are also referred to as "second resin" and "third resin," respectively), an extrusion unit 116 for extruding the regenerated resin obtained by kneading, a resin flow path 117 through which the extruded regenerated resin flows, and a filtration unit 118 for removing foreign matter contained in the resin composition during kneading.

[0023] The cylinder 111 is a container for kneading the recovered resin supplied inside with the screw 112. The cylinder 111 may have a heating section for adjusting the internal temperature to melt the recovered resin.

[0024] One or more screws 112 are arranged inside the cylinder 111 and are rotated by a motor (not shown) to knead the recovered resin inside the cylinder 111. A twin-screw extruder, consisting of two screws, can adjust its kneading characteristics by combining screw segments with various types of kneading characteristics, such as forward flight, kneading, and reverse flight. These combinations should be appropriately selected depending on the type and physical properties of the resin. Furthermore, extruders consisting of multiple screw shafts can also be appropriately selected depending on the kneading performance.

[0025] The ratio (L / D) of the length (L) to the diameter (D) of the screw 112 is preferably 20 to 80, more preferably 25 to 70, and even more preferably 30 to 50. By setting the L / D to 20 or higher, the three types of resins can be sufficiently melted and kneaded. By setting the L / D to 80 or lower, excessive rises in resin temperature can be suppressed, and power consumption can be reduced.

[0026] The hopper 113 is a supply port for supplying recovered resin into the cylinder 111. In this embodiment, the hopper 113 supplies recovered resin, including polyethylene and polypropylene, which has been recovered from, for example, a discarded automobile and separated by magnetic separation and specific gravity separation after crushing, into the cylinder 111. The hopper 113 has a storage section 114, which is a container for temporarily storing the recovered resin before it is supplied to the kneader 110. The storage section 114 has an agitator 114a inside the container, and the stored recovered resin can be stirred by the agitator 114a.

[0027] The agitator 114a can be a dry blender such as a tumble mixer, V-blender, ribbon blender, two-roll mixer, shaker, or buffer tank with internal rotor blades.

[0028] Hopper 115 is a supply port for supplying two or more types of additive resins into the cylinder 111. Hopper 115 may be in the same position as hopper 113, and the recovered resin (first resin) and additive resins (second and third resins) may be supplied into the cylinder 111 simultaneously from both hopper 115 and hopper 113. These additive resins all have known viscosity or MFR, and their viscosities or MFRs are different from each other. They are added to and mixed with the recovered resin to adjust the viscosity of the recovered resin to a predetermined range. These additive resins may be the same type of resin as the recovered resin (polyethylene or polypropylene in this embodiment), or they may be a different type of resin from the recovered resin, but in this embodiment, polypropylene is used.

[0029] The hopper 115 has a second resin supply unit 115a that supplies a second resin to the hopper 115, and a third resin supply unit 115b that supplies a third resin to the hopper 115. Both the second resin supply unit 115a and the third resin supply unit 115b can change the amount of the second or third resin supplied by a valve (not shown). This allows the hopper 115 to vary the supply amounts of two or more types of additive resins. In this embodiment, the hopper 115, under the control of the control unit 130, changes the supply amounts of two or more types of additive resins according to the viscosity of the recovered resin measured by the viscometer 120. The method by which the control unit 130 determines the supply amount of each additive resin supplied from the hopper 115 will be described later.

[0030] The kneader 110 may also have a separate hopper as a supply port for supplying additives such as stabilizers, antioxidants, and nucleating agents, reinforcing fiber materials such as glass fibers, carbon fibers, and organic fibers, and fillers such as rubber, talc, and calcium carbonate into the cylinder 111. Since the change in viscosity due to the addition of a certain amount of these fillers is within a range that can be predicted by theoretical or empirical formulas, the supply of these additives does not make the viscosity of the resulting recycled resin unpredictable. The kneader 110 may also be equipped with a venting mechanism for degassing.

[0031] The filtration unit 118 filters the kneaded resin composition. The filtration unit 118 can remove foreign matter such as soil and sand contained in the recovered resin, thereby suppressing the incorporation of foreign matter into the recycled resin. The filtration unit 118 can be a known filter.

[0032] The extrusion unit 116 has a die and the like, and extrudes the recovered resin, which has been supplied into the cylinder 111 and melted and kneaded by the rotation of the screw 112, into the resin flow path 117. The extrusion unit 116 can be a known gear pump or the like. In particular, using a gear pump that can accurately measure the discharge volume is preferable because it can improve the accuracy of viscosity calculation.

[0033] The resin channel 117 is a channel through which the recycled resin extruded from the extrusion section 116 flows while remaining in a molten state. The resin channel 117 is equipped with a viscometer 120. The resin channel 117 may also have a heating section to adjust the temperature inside the channel to facilitate the flow of the recycled resin.

[0034] The viscometer 120 is an inline viscometer that measures the viscosity of the recycled resin obtained by melt-kneading in the kneader 110. The viscometer 120 can be any known viscometer that measures the viscosity of a portion of the recovered resin extruded after melt-kneading in the kneader 110. For example, devices for measuring viscosity inline are described in R. Gendron, LE Daigneault, J. Cell. Plast., 35, 221 (1999). and M. Lee, CB Park, C. Tzoganakis, Polym. Eng. Sci., 39, 99 (1999). Alternatively, a viscometer with viscosity measurement piping as described in Japanese Patent Application No. 2022-075959 by the present inventor may be used.

[0035] It goes without saying that the configuration of the kneading device 100 is not limited to this. For example, the recycled resin kneaded in the kneader 110 and passed through the filtration section 118 may pass through the die, viscometer 120, static mixer, gear pump, screen changer, and extruder in that order, or the recycled resin kneaded in the kneader 110 and passed through the filtration section 118 may pass through the die, viscometer 120, gear pump, screen changer, and extruder in that order. As in the first example, a static mixer may be installed immediately before the viscometer 120. Installing a static mixer, which has the effect of exchanging the positions of the wall surface and the center of the pipe, immediately before the viscometer 120 is thought to minimize the effect of the recycled resin, which has been melt-kneaded in the kneader 110, remaining on the inner wall surface of the connected conduit, thereby improving the stability of the viscosity measurement.

[0036] The thermometer 125 is placed in the same position as the viscometer 120 and measures the temperature of the resin when measuring viscosity. The thermometer 125 can be any known thermometer.

[0037] The operation of the kneader 110 and the viscometer 120 is controlled by the control unit 130 (see Figure 3).

[0038] The control unit 130 can be a known computer and has a CPU 132 (Central Processing Unit), RAM 134 (Random Access Memory), ROM 136 (Read Only Memory), and storage unit 138. The CPU 132 reads various control programs and setting data stored in the ROM 136, stores them in the RAM 134, and executes the programs to perform various calculations. The CPU 132 also provides overall control of the mixing apparatus 100, including the mixer 110 and viscometer 120. The RAM 134 provides the CPU 132 with working memory space and stores temporary data. The RAM 134 may also include non-volatile memory. The ROM 136 stores various control programs and setting data executed by the CPU 132. Instead of the ROM 136, rewritable non-volatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory) or flash memory may be used. The storage unit 138 stores jobs and data related to those jobs that are input from the outside via the input / output interface 142. For example, an HDD (Hard Disk Drive) may be used as the storage unit 138, and DRAM (Dynamic Random Access Memory) may also be used in combination.

[0039] The following describes the method for producing recycled resin according to this embodiment, using the above-mentioned kneading apparatus 100, through steps 1 to 5.

[0040] 1-2. Supply of recovered resin (Step 1-1: Step S110) In step 1-1, the hopper 113 supplies the recovered resin to the kneader 110. Specifically, the hopper 113 supplies the recovered resin (first resin) that was temporarily stored in the storage section 114 into the cylinder 111. The amount of recovered resin supplied at this time should be an amount corresponding to a predetermined ratio (volume fraction) of the recovered resin in the recycled resin. The control unit 130 controls the cylinder 111 (or heating section), so that the temperature inside the cylinder 111 in this step is such that both the recovered resin (first resin) and the added resins (second resin and third resin) are melted or flow.

[0041] At this time, the agitator 114a can also suppress rapid and non-uniform viscosity fluctuations of the supplied recovered resin by stirring the recovered resin stored inside the storage section 114.

[0042] 1-3. Supply of additive resin (Steps 1-2: Step S120) In the first and second steps, the hopper 115 supplies two or more additive resins into the cylinder 111. In this embodiment, the hopper 115 supplies a second resin with a higher viscosity (or a lower MFR) and a third resin with a lower viscosity (or a higher MFR) into the cylinder 111.

[0043] Specifically, the hopper 115 supplies one additive resin (second resin) and another additive resin (third resin) into the cylinder 111. Immediately after starting the production of recycled resin, the hopper 115 supplies predetermined amounts of both the second and third resins into the cylinder 111. Subsequently, under the control of the control unit 130, the supply amounts of the second resin and the third resin are continuously changed by the control unit 130 to the amounts determined by the control unit 130 in steps 1-5.

[0044] Two or more additive resins may be used, provided their melt flow rates (MFRs) are known and differ from each other. The measurement conditions for the melt flow rate (MFR) should be selected appropriately depending on the type of resin used, in accordance with JIS K7210 (2014) or ASTM D1238 (2013). For example, polyethylene resins may be measured under a 2.16 kg load at 190°C, and polypropylene resins under a 2.16 kg load at 230°C.

[0045] Furthermore, the second or third resin preferably has an MFR of 1 g / 10 min or more and 300 g / 10 min or less, and the ratio of the MFR of the second resin to the MFR of the third resin (MFR of the third resin / MFR of the second resin), measured under the same conditions, is preferably 2 to 100, more preferably 2.5 to 50, and even more preferably 3 to 20.

[0046] The second resin preferably has an MFR of 1 g / 10 min to 50 g / 10 min, more preferably 3 g / 10 min to 45 g / 10 min, and even more preferably 5 g / 10 min to 30 g / 10 min. The third resin preferably has a melt flow rate of 20 g / 10 min to 300 g / 10 min, more preferably 25 g / 10 min to 250 g / 10 min, and even more preferably 30 g / 10 min to 200 g / 10 min.

[0047] Furthermore, the order in which steps 1-1 and 1-2 are performed does not matter, and the recovered resin and the added resin may be supplied to the inside of cylinder 111 simultaneously.

[0048] 1-4. Mixing (Steps 1-3: Step S130) In steps 1-3, the kneader 110 mixes the recovered resin (first resin) supplied into the cylinder 111 and the added resins (second and third resins) that are molten inside the cylinder 111. Specifically, the kneader 110 rotates the screw 112 to mix the recovered resin and the added resins, and moves the mixed recovered resin and added resins toward the exit of the cylinder 111 (towards the extrusion section 116). The rotational speed of the screw 112 at this time is adjusted to a rotational speed that yields the target discharge amount, and can be changed as needed depending on the properties and shape of the recovered resin.

[0049] The above kneading process yields recycled resin. The obtained recycled resin is extruded from the extrusion section 116. The extruded recycled resin flows through the resin channel 117.

[0050] 1-5. Viscosity η of recycled resin d Measurement (Steps 1-4: Step S140) In steps 1-4, the viscometer 120 measures the viscosity η of the recycled resin flowing through the resin channel 117. d The viscosity is measured. The viscosity measured here is so-called melt viscosity. In this specification, viscosity refers to melt viscosity based on a measurement temperature of 230°C and a shear rate of 1.0 (1 / s) at the time of measurement. However, viscosity measurements at other temperatures and shear rates can be easily converted to the same temperature and shear rate using the relationship formula described later. Therefore, the viscosity measurement conditions can be freely set without any particular restrictions, or linked to the temperature conditions and operating information of the extruder. (Note that these measurement conditions are for resins including polyethylene and polypropylene. When using other resins, the measurement conditions commonly used for those resins should be used.) The viscometer 120 transmits the measured viscosity to the CPU 132. The CPU 132 temporarily stores the measured viscosity in the memory unit 138.

[0051] 1-6. Change in supply quantity (Process 1-5: Process S150) In steps 1-5, the control unit 130 determines the viscosity η of the recycled resin measured by the viscometer 120 in step 1-4. dThe control unit 130 receives data indicating the viscosity of the two or more additive resins supplied in the first and second steps, and changes the supply amount of each of the two or more additive resins according to the viscosity of the data. The control unit 130 may change the proportion of the amount of each additive resin in the total amount of additive resin while keeping the proportion of the amount of additive resin supplied in the first and second steps constant, or it may change the amount of each additive resin so as to change the proportion of additive resin in the recycled resin.

[0052] Figure 4 is a flowchart showing each subprocess in the process in which the control unit 130 changes the supply amount of additive resin in this process. In this process, the control unit 130 first changes the viscosity η of the recycled resin. d From this, the viscosity η1 of the recovered resin (first resin) is calculated (step 1-5a-1, step S150a). Then, from the calculated viscosity η1 of the first resin, the viscosity η of the obtained recycled resin is calculated. d The desired viscosity η final The amount of additive resin (second resin and third resin) to be supplied is determined to achieve the desired result (Step 1-5a-2, Step S150b). The control unit 130 further changes the amount of additive resin (second resin and third resin) supplied from the hopper 115 to the determined amount (Step 1-5a-3, Step S150c). The control unit 130 performs these subprocesses by storing the program stored in the ROM 136 in the RAM 134 and running the program. Each subprocess will be described below.

[0053] 1-6-1. Calculation of the viscosity η1 of the recovered resin (Step 1-5a-1: Step S150a) In this subprocess, the control unit 130, based on theories concerning polymer blending, such as the Double-Reptation theory (C. Tsenoglou, Macromolecules, 24, 1762-1767 (1991)), determines the volume fraction φ1 of the recovered resin (first resin), the respective volume fractions φ2 and φ3 of the added resins (second and third resins), the known viscosities η2 and η3, and the viscosity η of the obtained recycled resin. d From this, the viscosity η1 of the recovered resin (first resin) is calculated.

[0054] According to the Double-Reptation theory, in a three-component system, the viscosity η of a mixture of a first resin, a second resin, and a third resin Blend can be expressed by the following formula (1).

[0055]

Equation

[0056] In formula (1), φ1 represents the volume fraction of the recovered resin (first resin) supplied by hopper 113, the volume of one additional resin (second resin) supplied by hopper 115, and the volume of another additional resin (third resin) supplied by hopper 115, with respect to the total volume (the total volume of resin components supplied inside cylinder 111) of the recovered resin (first resin), η1 represents the viscosity of the first resin, φ2 represents the volume fraction of one additional resin (second resin) with respect to the total volume of resin components supplied inside cylinder 111, η2 represents the viscosity of the second resin, φ3 represents the volume fraction of another additional resin (third resin) with respect to the total volume of resin components supplied inside cylinder 111, η3 represents the viscosity of the third resin, and η Blend represents the viscosity of the resulting mixture.

[0057] Among these variables, φ1, φ2, φ3, η2, and η3 are known. Therefore, by substituting the viscosity η of the recycled resin (mixture) measured by viscometer 120 into η d and substituting it into η Blend the viscosity η1 of the first resin, which is the remaining variable, can be calculated by inverse calculation.

[0058] The volume fraction φ1 of the recovered resin (first resin) can be set in a predetermined range, for example, in the range of 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).

[0059] (Regarding the handling of viscosities η2 and η3) The temperature dependence and shear rate dependence of the melt viscosity of the additive resin can be determined by the following method.

[0060] Using a commercially available rotary rheometer or other device for measuring the melt viscoelasticity of polymers (for example, the Discovery Hybrid Rheometer (DHR10) from TA Instruments), 3 to 5 temperature levels are appropriately selected within the temperature range from the melting point Tm+10°C to Tm+100°C for crystalline resins, and from the glass transition temperature Tg+10°C to Tg+200°C for amorphous resins, and the linear viscoelastic functions (G', G'') are measured in the frequency range ω=0.1~500 (rad / s).

[0061] From this linear viscoelastic function, a master curve is created based on the time-temperature conversion rule, with a reference temperature T0 = 230°C. This operation can be easily performed using the software included with the rheometer mentioned above.

[0062] The ratio of viscosity obtained at other temperatures T to viscosity at the reference temperature T0 is the shift factor a of the time-temperature conversion rule obtained when creating the master curve. T It can be expressed as follows:

[0063]

number

[0064] This shift factor is expressed by the following Arrhenius equation for most crystalline resins, where E is the activation energy (J / mol) and R is the gas constant.

[0065]

number

[0066] Using the linear viscoelastic function complex viscosity |η*(ω)|, and applying the Cox-Marz law (Cox, WP and Merz, EH : J. Polym. Sci., 28, 619 (1958)), frequency (ω) = shear rate (γ SR By doing this, we can determine the temperature dependence and shear rate dependence of the melt viscosity.

[0067] Note that the shear rate r SR In the formula, it is represented by the following symbol.

[0068]

number

[0069] The rheological model (Carreau-Yasuda model: Yasuda, K., Armstrong, RC and Cohen, RE: Rheol. Acta, 20, 163 (1981)) that represents the shear rate dependence of melt viscosity is as follows:

[0070]

number

[0071] Here, η0, n, λ, and a are model parameters, representing zero shear viscosity, non-Newtonian exponent, relaxation time, and parameters related to the transition from the Newtonian to the non-Newtonian region, respectively.

[0072] Combining equation (3), which represents the temperature dependence of viscosity, and equation (4), which represents the shear rate dependence, viscosity can be expressed as follows:

[0073]

number

[0074] By fitting the above measurement results to this formula and determining the parameters, the viscosity at any given temperature and shear rate can be quickly calculated.

[0075] If they are the same type of resin, then η1, η d η Final Since the parameters in equation (3) for the temperature dependence of the viscosity are almost the same as those for the additive resin, the same parameters as those for the additive resin may be used.

[0076] The shear rate is η d You can either match the value to the shear rate at which the measurement was taken, or you can use an in-line viscometer that can simultaneously measure viscosity at three or more shear rates to obtain the model parameters of equation (4).

[0077] Melt flow rate (MFR) is commonly used as an indicator of resin fluidity. Commercial resins have their melt flow rate listed on their product labels, and it is convenient to use this value as a reference when selecting additive resins (secondary and tertiary resins).

[0078] The relationship between the melt viscosity of the additive resin and the melt flow rate can be considered as follows (Takeharu Izaki, Molding and Processing, Vol. 22, October issue, pp. 556-561 (2010)).

[0079] Melt flow rate (MFR) is measured as the flow rate of a polymer molten material from a capillary under a constant load, where σ = ηγ is the stress when a constant load F is applied. SR This can be determined from equation (5). Furthermore, the relationship between shear rate and flow rate Q is expressed by equation (6).

[0080]

number

[0081] That is, the shear rate γ obtained from viscosity measurement. SR -The shear rate at which the stress corresponding to a load of 2.16 kg (σ = 19360 Pa) is obtained from equation (5) in the shear stress σ plot, and the flow rate Q[(m 3By converting to [(g / 10min)], multiplying by the density ρ, and converting the unit back to [(g / 10min)], the MFR can be calculated from this flow rate.

[0082]

number

[0083] Here, MFR: (g / 10min), ρ: polymer density (g / cm³) 3 ), r: MFR gauge hole radius (cm), γ SR : This is the shear rate (1 / s).

[0084] 1-6-2. Determination of the amount of additive resin to be supplied (Step 1-5a-2: Step S150b) In this subprocess, the control unit 130 calculates the viscosity η of the recovered resin (first resin) calculated in the previous subprocess (step 1-5a-1). d Based on this, the viscosity of the recycled resin is the desired viscosity η final The supply amounts of additive resins (second resin and third resin) are determined so that η d Although it is a function of temperature and shear rate, it will be treated as converted to the base state, and from now on η d We will only write it as that.

[0085] Specifically, the control unit 130 calculates the viscosity η1 of the recovered resin (first resin), the viscosity η2 of the additive resin (second resin), the viscosity η3 of the additive resin (third resin), and the volume fraction φ1 of the recovered resin (first resin) based on the viscosity η1 of the recovered resin (first resin) calculated in the previous subprocess (step 1-5a-1), and then uses the above-mentioned formula (1) to calculate η Blend The target viscosity η of the recycled resin final Determine the volume fraction φ2 of the second resin and the volume fraction φ3 of the third resin such that (since φ2 + φ3 = 1 - φ1, this calculation can be done using a quadratic equation). Then, calculate the supply amounts of the second resin and the third resin according to the determined volume fractions φ2 and φ3 of the second and third resins, and determine these as the supply amounts of the second and third resins.

[0086] 1-6-3. Change in the supply amount of additive resin (Step 1-5a-3: Step S150c) In this subprocess, the control unit 130 changes the supply amount of additive resin (second resin and third resin) from the hopper 115 so that the supply amounts of the second resin and third resin determined in the previous subprocess (step 1-5a-2) are supplied into the cylinder 111.

[0087] Specifically, the control unit 130 controls the operation of the second resin supply unit 115a and the third resin supply unit 115b of the hopper 115 to change the amount of second resin and the amount of third resin supplied by these supply units to the hopper 115 to the amount determined in the previous subprocess (step 1-5a-2). As a result, the amount of second resin and the amount of third resin supplied from the hopper 115 to the inside of the cylinder 111 are changed.

[0088] The operation of the control unit 130 in this subprocess can be determined according to the method of supplying the second resin and the third resin to the kneader 110. For example, if the kneader 110 has separate hoppers for supplying the second resin and the third resin, the control unit 130 can control the operation of these multiple hoppers to change the supply amounts of the second resin and the third resin.

[0089] The amount of additive resin supplied in this process (steps 1-5) may be changed only once, multiple times periodically or irregularly, or continuously. The viscosity of the recovered resin changes depending on the source of recovery, recovery time, storage conditions, and usage period. Therefore, in this embodiment, the viscosity η1 of the recovered resin (first resin) supplied from the hopper 113 into the cylinder 111 is not constant but changes over time. Viscosity η of the recycled resin dFrom the viewpoint of stabilizing the mixture to a constant viscosity, it is preferable to change the supply amounts of the second resin and the third resin over time in accordance with the viscosity η1 of the recovered resin (first resin) which is changing. For this reason, it is preferable to change the supply amount of the added resin in this process (steps 1-5) multiple times or to continue doing so continuously, and it is more preferable to continue doing so continuously.

[0090] 1-7. Determination of whether or not there is any remaining recovered resin (Steps 1-6, Step S160) The control unit 130 then determines whether all of the recovered resin stored in the storage unit 114 has been supplied to the cylinder 111, or in other words, whether there is any recovered resin remaining in the storage unit 114 (steps 1-6, step S160). Whether or not there is any recovered resin remaining in the storage unit 114 can be determined, for example, by checking with a sensor built into the storage unit 114, or by calculating the difference between the amount of recovered resin supplied to the storage unit 114 and the amount of recovered resin supplied from the hopper 113 into the cylinder 111.

[0091] When all the recovered resin has been supplied to the cylinder 111 and it is determined that no recovered resin remains in the storage unit 114, the control unit 130 stops the operation of the kneading device 100 after the recovered resin and added resin currently being kneaded inside the cylinder 111 have been extruded from the extrusion unit 116. If it is determined that recovered resin remains in the storage unit 114, the control unit 130 repeats and continuously performs steps 1-1 to 1-5. Note that new recovered resin may be supplied to the storage unit 114 while this embodiment is being performed.

[0092] (effect) According to this embodiment, viscosity fluctuations in the resulting recycled resin caused by viscosity fluctuations in the recovered resin can be controlled, and recycled resin with more uniform viscosity can be obtained.

[0093] Incidentally, the viscosity of the recycled resin measured by the viscometer 120 is the viscosity after the recovered resin (first resin) has been supplied from the hopper 113 into the cylinder 111 and has been kneaded for a predetermined time. Therefore, the viscosity η1 of the recovered resin (first resin) obtained in step 1-5-1 from the viscosity of the recycled resin measured by the viscometer 120 is not the viscosity of the recovered resin (first resin) added at the time the viscosity was measured, but the viscosity of the recovered resin supplied a predetermined time earlier. Furthermore, as mentioned above, the viscosity of the recovered resin (first resin) changes over time. Therefore, even if the supply amounts of the second resin and the third resin are determined from the viscosity of the recovered resin a predetermined time earlier, the viscosity of the first resin supplied at that time has changed, so the viscosity of the recovered resin obtained will not match the target viscosity η. final This is not always the case. However, the viscosity of the recovered resin (first resin) does not change irregularly and with large fluctuations, but usually fluctuates with a predetermined period. And, as shown in the calculation example described later, the viscosity η of the recycled resin obtained by performing the method shown in this embodiment is d It is possible to reduce the rate of change.

[0094] 2. Second Embodiment In the first embodiment, the viscosity η of the recycled resin is measured by the viscometer 120. d The η1 of the recovered resin (first resin) was calculated, and the supply amounts of the second resin and the third resin were determined by calculations using the calculated η1 of the recovered resin (first resin). In this embodiment, the calculated viscosity η1 (viscosity of the recovered resin (first resin) supplied in the past. Hereinafter, "η 1-past "The viscosity of the recovered resin (first resin) at present is determined from the change over time of the following: η1 (the viscosity of the recovered resin (first resin) supplied at present. Hereinafter, "η 1-present ) predicts the predicted viscosity η 1-present The supply amounts of the second resin and the third resin are determined by calculations using this method.

[0095] In this embodiment, the flowchart for the method of manufacturing recycled resin and the configuration of the kneading apparatus used are the same as in the first embodiment (Figures 1 and 2), but the method for changing the supply amount of each of the two or more additive resins (steps 1-5, step S150) differs from the first embodiment. Hereinafter, redundant explanations of parts that are the same as the first embodiment will be omitted, and only the differences will be explained.

[0096] Figure 5 is a flowchart showing each subprocess in the first to fifth steps (step S150) of this embodiment, in which the control unit 130 changes the supply amount of additive resin. In this embodiment, the control unit 130 first determines the viscosity η of the recovered resin (first resin) from the viscosity of the recycled resin. 1-past The viscosity η is calculated (step 1-5b-1, step S150d). 1-past The viscosity η is stored (step 1-5b-2, step S150e). 1-past When it accumulates, the accumulated viscosity η 1-past Based on this, a prediction formula showing the change in viscosity η1 over time is created (Step 1-5b-3, Step S150f). Next, from the created prediction formula, the viscosity η of the recovered resin (first resin) at the present time is calculated. 1-present Predict the viscosity of the first resin (step 1-5b-4, step S150g). Then, predict the viscosity of the first resin η. 1-present From there, the amount of additive resin (second resin and third resin) to be supplied is determined so that the viscosity of the resulting recycled resin reaches the desired viscosity (step 1-5b-5, step S150h). Then, the control unit 130 changes the amount of additive resin (second resin and third resin) supplied from the hopper 115 to the determined amount (step 1-5b-6, step S150i). The control unit 130 performs these subprocesses by storing the program stored in the ROM 136 in the RAM 134 and running the program. Each subprocess will be described below.

[0097] 2-1. Viscosity of recovered resin η 1-past Calculation (Step 1-5b-1: Step S150d) In this subprocess, the control unit 130 determines the volume fraction φ1 of the recovered resin (first resin), the volume fractions φ2 and φ3 of the added resins (second resin and third resin), the known viscosities η2 and η3, and the viscosity η of the obtained recycled resin. d Therefore, the viscosity η of the recovered resin (first resin) 1-past The viscosity η of the recovered resin (first resin) is calculated. 1-past The method for determining the viscosity of the recovered resin (first resin) is the same as in step 1-5a-1 of the first embodiment. 1-past The calculation is performed multiple times, either periodically or irregularly, or continuously.

[0098] 2-2. Viscosity of recovered resin η 1-past Preservation (Step 1-5b-2: Step S150e) In this subprocess, the control unit 130 calculates the viscosity η of the recovered resin (first resin) calculated in the previous subprocess (step 1-5b-1). 1-past This, along with the measured time, is stored in RAM 134 or storage unit 138. Over time, viscosity η 1-past Data, linked to time, is accumulated.

[0099] 2-3. Creation of the prediction formula (Step 1-5b-3: Step S150f) After the amount of data accumulated in the previous subprocess (step 1-5b-2) reaches a predetermined amount, in this subprocess, the control unit 130 creates a predictive formula showing the change in viscosity η1 over time, for example, a mathematical formula showing the relationship between the elapsed time since the start of recycled resin production and viscosity η1, based on the accumulated data.

[0100] The method for creating the prediction formula is not particularly limited; for example, elapsed time and viscosity η 1-past We just need to find a linear or higher-order equation that approximates the relationship with viscosity η. In this case, we can use a moving average to find viscosity η. 1-past The change over time is smoothed out, and the smoothed viscosity η 1-past A prediction formula may be created based on the changes over time.

[0101] For example, η for the 600 seconds from the past 600 seconds to the present time 1-past Approximating this using a moving average to the linear approximation formula Y=AX+B, (Y=η 1-past X = time (seconds), and Y = η 600 seconds later. 1-present There are methods to predict X = time (seconds), etc. Furthermore, at this time, the maximum value of η1 known from past performance η 1-max or minimum value η 1-min Because there is a possibility of overestimating or underestimating η1 beyond its range, one possible approach is to combine the prediction formula with conditional branching to ensure that the predicted value never exceeds the maximum and minimum range.

[0102] As the manufacturing of recycled resin continues, new data is accumulated through the previous subprocess (step 1-5b-2). In this subprocess, it is preferable for the control unit 130 to update the prediction formula as new data is accumulated. At this time, the control unit may create a new prediction formula using all the data accumulated in the past, or it may create a new prediction formula using only the most recent data, for example, past data going back a predetermined time (for example, 10 minutes or more but 40 minutes or less) from the present. Alternatively, it may create a new prediction formula by extracting a predetermined number of data from the accumulated data.

[0103] 2-4. Viscosity of recovered resin η 1-present Prediction (Process 1-5b-4: Process S150g) In this subprocess, the control unit 130 uses the prediction formula created in the previous subprocess (step 1-5b-3) to determine the viscosity η of the recovered resin (first resin) currently supplied to the cylinder 111. 1-present To predict.

[0104] Specifically, the control unit 130 substitutes the current time (time elapsed since the start of recycled resin production) into the above prediction formula and uses the obtained value of η1 as the viscosity η of the recovered resin (first resin) at the current time. 1-present Let's assume that's the case.

[0105] 2-5. Determination of the amount of additive resin to be supplied (Step 1-5b-5: Step S150h) In this subprocess, the control unit 130 calculates the viscosity η of the recovered resin (first resin) calculated in the previous subprocess (step 1-5b-4). 1-present Based on this, the amount of additive resins (second resin and third resin) to be supplied is determined so that the viscosity of the recycled resin reaches the desired viscosity.

[0106] The method for determining the supply amount of additive resins (second resin and third resin) in this subprocess can be the same as that of step 1-5a-2 in the first embodiment.

[0107] 2-6. Change in the supply amount of additive resin (Step 1-5b-6: Step S150i) In this subprocess, the control unit 130 changes the supply amount of additive resin (second resin and third resin) from the hopper 115 so that the supply amounts of the second resin and third resin determined in the previous subprocess (step 1-5b-5) are supplied into the cylinder 111.

[0108] The method for determining the supply amount of additive resins (second resin and third resin) in this subprocess can be the same as that used in step 1-5a-3 of the first embodiment.

[0109] In this embodiment, the control unit 130 determines the viscosity η of the recovered resin (first resin) at the current time. 1-present The viscosity η of the recovered resin (first resin) at a predetermined time was predicted, and the amount of additive resin (second resin and third resin) to be supplied accordingly was determined. 1-present The amount of additive resin (second resin and third resin) to be supplied can be predicted and predetermined accordingly, and the amount of additive resin (second resin and third resin) supplied after a predetermined time can be changed to the predetermined amount.

[0110] (effect) According to this embodiment, the viscosity η of the recovered resin (first resin) predicted by the prediction formula has higher accuracy. 1-presentSince the amount of additive resin to be supplied can be determined using this method, a recycled resin with even more uniform viscosity can be obtained.

[0111] 3. Third Embodiment In the first and second embodiments, the viscosity of the resulting recycled resin was made uniform by changing the amount of added resin based on the viscosity of the resin after kneading. In contrast, in this embodiment, the control unit 130 performs further control to achieve even greater uniformity of the viscosity of the recycled resin. In this embodiment, the control performed by the control unit 130 can be performed independently and in parallel with the control in the first or second embodiment.

[0112] Figure 6 is a flowchart showing the processing of the control unit 130 in this embodiment. In this embodiment, the control unit 130 first processes the viscosity η of the recycled resin measured by the viscometer 120. d Data indicating this is received and stored (Step 3-1, Step S310). A predetermined amount of viscosity η d When it accumulates, the accumulated viscosity η d Based on this, viscosity η d The rate of change over time is calculated (Step 3-2, Step S320). Then, it is determined whether the calculated rate of change is within the acceptable range (Step 3-3, Step S330), and if it is not within the acceptable range, the viscosity η of the recycled resin is calculated. d A method for suppressing fluctuations is implemented or presented (Steps 3-4, Step S340). The control unit 130 performs these steps by storing the program stored in the ROM 136 in the RAM 134 and executing the program. Each step will be described below.

[0113] 3-1. Viscosity η d Preservation (Step 3-1: Step S310) In this process, the control unit 130 determines the viscosity η of the recycled resin measured by the viscometer 120. d Data indicating this is received and stored in RAM 134 or storage unit 138 along with the time of measurement. Over time, viscosity η dData, linked to time, is accumulated.

[0114] 3-2. Viscosity η d Calculation of the rate of change (Step 3-2: Step S320) After the amount of data accumulated in the previous process (3-1 process) reaches a predetermined amount, in this process, the control unit 130 calculates the viscosity η based on the accumulated data. d The rate of change over time is calculated. The method for calculating the rate of change is not particularly limited; for example, viscosity η d The difference (range of variation) between the maximum and minimum values ​​is the average value of viscosity ηd (or the target viscosity η). final You can divide by ) or viscosity η d Create an approximate formula that shows the change over time, and define the viscosity η in that approximate formula. d You can also calculate the rate of change.

[0115] 3-3. Viscosity η d Determination of the rate of change (Step 3-3: Step S330) In this process, the control unit 130 determines whether the rate of variation calculated in the previous process (step 3-2) falls within a predetermined range of acceptable rates of variation. The acceptable rate of variation can be arbitrarily determined depending on the intended use of the recycled resin. If it is determined that the calculated rate of variation falls within the acceptable range, the viscosity of the recycled resin can be considered sufficiently uniform, and the control unit 130 terminates the process in this step.

[0116] 3-4. Implementation and presentation of methods for suppressing fluctuations (Step 3-4: Step S340) If it is determined in the previous step that the calculated rate of variation is not within an acceptable range, the control unit 130 determines the viscosity η of the recycled resin. d Implement or provide workers with methods to suppress fluctuations.

[0117] For example, if fluctuations in the viscosity η1 of the recovered resin supplied into the cylinder 111 are suppressed (for example, by making the fluctuation period longer), the viscosity η of the resulting recycled resin will be dFluctuations in the viscosity can also be suppressed. Therefore, in this process, the control unit 130 may increase the degree of stirring of the recycled resin in the storage unit 114 by increasing the rotation speed of the stirrer 114a in the storage unit 114 in order to suppress fluctuations in the viscosity η1 of the supplied recovered resin.

[0118] Alternatively, the supply of recovered resin into the cylinder 111 and the viscosity η of the recycled resin obtained from the supplied recovered resin d By measuring and shortening the interval between measurements, the viscosity η1 of the recovered resin in the more recent past is used to determine the viscosity η of the recycled resin. d It may also be possible to calculate it from. This makes it possible to reduce the difference between the calculated viscosity of the recovered resin and the viscosity of the recovered resin at that point in time, which is caused by fluctuations in the viscosity η1 of the recovered resin, and the viscosity η of the recycled resin obtained by adding the amount of additive resin determined in steps S150b and S150h d The target viscosity η final It can also be made to be closer to it.

[0119] Specifically, in this process, the control unit 130 may shorten the mixing time between the recycled resin and the additive resin inside the cylinder 111 by increasing the rotational speed of the screw 112. Alternatively, the mixing time between the recycled resin and the additive resin inside the cylinder 111 may be shortened by positioning the hopper 115, which supplies the additive resin, downstream of the extruder. The kneader 110 may be configured such that the hopper 113 and hopper 115 can be repositioned along the cylinder 111 in the direction of resin flow, and the mixing time between the recycled resin and the additive resin inside the cylinder 111 can be changed by changing the positions of the hopper 113 and hopper 115 under the control of the control unit 130. In this specification, mixing time refers to the time from when two or more types of additive resins are added to the recovered resin until the viscosity is measured.

[0120] For example, the mixing time of the recovered resin and the added resin inside the cylinder 111 (the time from when both the recovered resin and the added resin are supplied inside the cylinder 111 until they are extruded from the extrusion unit 116) can be between 1 minute and 50 minutes, but is preferably between 3 minutes and 30 minutes, and more preferably between 5 minutes and 20 minutes.

[0121] Alternatively, even if the volume fraction φ1 of the recovered resin (first resin) supplied into the cylinder 111 is made smaller relative to the total supplied resin, and the volume fraction (φ2 + φ3) of the added resin is made larger, the viscosity η of the resulting recycled resin is still the same. d This can suppress fluctuations. Therefore, in this process, the control unit 130 may reduce the volume fraction φ1 of the recovered resin (first resin) by reducing the amount of recovered resin (first resin) supplied from the hopper 113, increasing the amount of additive resins (second and third resins) supplied from the hopper 115, or controlling both.

[0122] Alternatively, the capacity of the storage unit 114 can be increased to reduce fluctuations in the viscosity η1 of the recovered resin inside the storage unit 114, or the capacity of the cylinder 111 can be reduced, or the ratio of the length (L) to the diameter (D) of the screw 112 can be changed to shorten the mixing time of the recovered resin and the added resin inside the cylinder 111. At this time, the control unit 130 can communicate the viscosity η of the recycled resin via the input / output interface 142. d A signal may be sent to an external display to indicate (present) that there are large fluctuations and that the above-mentioned countermeasures are recommended.

[0123] For example, the capacity of the storage section 114 can be larger than the capacity of the cylinder 111, preferably three times or more the capacity of the cylinder 111, and more preferably five times or more the capacity of the cylinder.

[0124] In this embodiment, the control unit 130 controls the viscosity η of the recycled resin. dControl was performed to suppress the fluctuations. Conversely, when the calculated rate of change is within the allowable range, the control unit 130 may reduce the degree of agitation for energy saving, increase the kneading time of the recycled resin and the added resin inside the cylinder for more thorough kneading, or increase the proportion of the recycled resin to achieve more efficient recycling with less added resin.

[0125] (Effect) According to the present embodiment, recycled resin with more uniform viscosity can be obtained.

[0126] [Other Embodiments] It should be noted that each of the above-described embodiments shows an example of the present invention, and the present invention is not limited to each of the above-described embodiments. Needless to say, various other embodiments are possible within the scope of the idea of the present invention.

[0127] For example, in each of the above-described embodiments, the kneading device 100 measures the viscosity of the recycled resin extruded from the extrusion unit 116 and flowing through the resin flow path 117 using the viscometer 120. However, the kneading device 100 may have a viscometer that measures the viscosity of these resins inside the cylinder 111 and measure the viscosity of the resin being kneaded inside the cylinder 111. The viscosity to be measured at this time may be the viscosity after the recycled resin and the added resin are supplied. As shown in the third embodiment, after the supply of the recycled resin and the added resin, the shorter the time until the viscosity η d of the recycled resin is measured, the more efficiently the viscosity η d of the recycled resin can be made uniform. From this perspective, measuring the viscosity inside the cylinder 111 is preferable because it contributes to the uniformization of the viscosity η d of the recycled resin.

[0128] Furthermore, in the embodiments described above, an additive resin, which is either polyethylene or polypropylene, was added to the recovered resin containing polyethylene and polypropylene, but the types of resins used are not limited to these. In the present invention, the recovered resin and the additive resin may be one of a variety of resins, including polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), polycarbonate, and polyester, or a combination thereof. These resins may be off-grade materials or separated and sorted recovered materials. From the viewpoint of reducing carbon dioxide emissions, biomass plastics made from plant resources, plastics that partially contain biomass raw materials using a mass balance method, or biodegradable plastics can also be used. Naturally, the recycled resin produced may also contain these resins.

[0129] Furthermore, in each of the embodiments described above, the viscosity η of the recovered resin supplied according to the Double-Reptation theory 1-past While the calculations involved working backward and determining the amount of additive resin to supply (volume fractions φ2 and φ3 of the second and third resins) based on η1, other theories showing the relationship between the amount of each polymer and the viscosity of the mixture when blending polymers may also be used.

[0130] Furthermore, in the second embodiment described above, two types of additive resins were added to the recovered resin, but three or more types of additive resins may be added. In this case, by changing only the amounts of the two types of additive resins and keeping the amounts of the other additive resins constant, the above calculation can be extended to when three or more types of additive resins are added. In addition, additives such as stabilizers, antioxidants, and nucleating agents, fillers such as rubber, talc, and calcium carbonate, and reinforcing fiber materials such as glass fibers, carbon fibers, and organic fibers may also be added to the cylinder 111.

[0131] Furthermore, in each of the embodiments described above, recovered resin was added to the cylinder 111, but not only recovered resin, but also virgin material may be added to the cylinder 111, or natural resin or biomass plastic of unknown viscosity may be added to the cylinder 111. In addition, liquid ethylene-propylene rubber, pelletized ethylene-propylene rubber, ethylene-butene rubber, propylene-butene rubber, or propylene-butene-ethylene rubber may be added to the cylinder 111 as a compatibilizer such as a copolymer of polyethylene and polypropylene.

[0132] Furthermore, in each of the embodiments described above, the extrusion unit may extrude the recycled resin into any known shape, including sheets, films, rods, plates, pipes, molded products with irregular cross-sections, and strands. Alternatively, a cutter or the like may be placed downstream of the extrusion unit to process the extruded recycled resin into pellets. Or, a known molding machine may be placed downstream of the extrusion unit to mold the extruded recycled resin into a predetermined shape.

[0133] Furthermore, the control unit 130 may store the relationship between the state of the recovered resin at the time of recovery (source of recovery, recovery time, storage period, and usage period) received from the input / output interface 142 and the viscosity η1 of the recovered resin calculated in the 1st-5a-1 step (step S150a) and the 1st-5b-1 step (step 150b), and generate an estimation model that estimates the viscosity η1 of the recovered resin from the state of the recovered resin using machine learning with these as training data. Then, the viscosity η1 of the recovered resin may be output from the state of the recovered resin using this estimation model, or the above estimation model created in advance. Alternatively, the estimation model may be updated by retraining based on the viscosity η1 of the recovered resin calculated by repeatedly performing each of the above steps and the state of the recovered resin at the time of recovery.

[0134] [simulation] Assume that the viscosity η1 of the recycled resin to be supplied varies in a predetermined cycle with a central value of 2000 Pas and an amplitude of ±500 Pas. An additive resin (second resin) with a viscosity η2 of 800 Pas (constant) and an additive resin (third resin) with a viscosity η3 of 5000 Pas (constant) are added to a kneader and kneaded in the kneader, and then extruded. The viscosity η of the recycled resin obtained by extrusion d was simulated over time.

[0135] The simulation conditions are as follows. Second resin: Polypropylene, viscosity η2 = 800 Pas, MFR = 30 g / 10 min Third resin: Polypropylene, viscosity η3 = 5000 Pas, MFR = 3.0 g / 10 min Density of the resin mixture in the molten state: 760 kg / m 3 Volume of the recycled resin storage section (hopper): 1 m 3 Kneader: Extruder (φ90 mm, L / D = 35, internal volume including the filtration section 0.023 m 3 ) Discharge rate: 100 kg / h

[0136] Note that the viscosity of each resin was the viscosity measured at a measurement temperature of 230 °C and a shear rate of 1.0 (1 / s) during measurement. The MFR was the value measured under the conditions of a 2.16 kg load and 190 °C in accordance with JIS7210 (2014). Also, the volume fraction of the supply amount of the recycled resin with respect to the total volume of the resin supplied to the kneader was φ1, the volume fraction of the supply amount of the second resin was φ2, and the volume fraction of the supply amount of the third resin was φ3 (φ1 + φ2 + φ3 = 1). At this time, the target viscosity η of the obtained recycled resin final was set to 2200 Pas, and the viscosity η of the recycled resin d was η final To achieve this, the control shown in the following calculation example was performed, and the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin were continuously changed.

[0137] [Calculation Example 1] (Example) The viscosity η of the recycled resin is calculated as follows, assuming a variation period of viscosity η1 of the recovered resin is 120 minutes, φ1=0.5, φ2=0.3, φ3=0.2, and the mixing time of the recovered resin and added resin in the kneader is 600 seconds. d The change over time was simulated. Specifically, the viscosity η of the recycled resin was measured. d Then, using the volume fraction φ2 of the amount of the second resin supplied 600 seconds ago and the volume fraction φ3 of the amount of the third resin supplied, the viscosity η of the recovered resin supplied 600 seconds ago is calculated using the following formula (1). 1-past We worked backwards. Then, using the following formula (1), we calculated the viscosity of the recycled resin at the present time η d The viscosity of the recovered resin supplied at the time of measurement is η 1-past The viscosity η of the recycled resin obtained when the viscosity is calculated as the viscosity 600 seconds ago. d The target viscosity η final The volume fractions φ2 of the supply amount of the second resin and φ3 of the supply amount of the third resin were calculated, and φ2 and φ3 were changed to the calculated values.

[0138]

number

[0139] Since the viscosity η1 of the recovered resin fluctuates, the viscosity η of the resulting recycled resin will vary. d The viscosity η of the recycled resin also fluctuates. d Based on this, the viscosity η of the recovered resin supplied 600 seconds ago 1-past The reverse calculation, and the viscosity of the recovered resin obtained by the reverse calculation η 1-past Assuming that η1 is the current value, the volume fractions φ2 of the second resin supply and φ3 of the third resin supply were continuously calculated. Then, while keeping the volume fraction φ1 of the recovered resin supply constant, the volume fractions of the second resin supply and the third resin supply were continuously changed to the calculated volume fractions φ2 and φ3.

[0140] Figure 7 shows η1 at this time and η calculated 600 seconds prior. 1-past(The calculated value is plotted 600 seconds before the calculation time.) Measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0141] The viscosity of the recycled resin measured η d Based on this, by changing the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin, the viscosity η of the recycled resin is lower than when φ2 and φ3 are not changed (calculation example 11). d The rate of fluctuation became smaller. While the amplitude of the viscosity η1 of the supplied recovered resin is 25% (500 Pas / 2000 Pas), in this calculation example, the viscosity η of the recycled resin during 3 hours from the start of resin discharge (600 seconds after the start of operation) d The rate of change was 14.0%.

[0142] [Calculation Example 2] (Example) The fluctuation period of the recovered resin viscosity η1 was set to 240 minutes, and the same simulation as in Calculation Example 1 was performed without changing other conditions. Figure 8 shows the recovered resin viscosity η1 at this time and the calculated viscosity η of the recovered resin 600 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0143] If the fluctuation period of the viscosity η1 of the recovered resin is made longer than in Calculation Example 1, the viscosity η of the recycled resin d The rate of variation became smaller. Viscosity η of recycled resin in this calculation example d The rate of change was 6.8%.

[0144] [Calculation Example 3] (Example) The fluctuation period of the viscosity η1 of the recovered resin was set to 480 minutes, and the same simulation as in Calculation Example 1 was performed without changing other conditions. Figure 9 shows the viscosity η1 of the recovered resin at this time, and the calculated viscosity η of the recovered resin 600 seconds prior. 1-pastThe viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0145] If the fluctuation period of the viscosity η1 of the recovered resin is further increased, the viscosity η of the recycled resin d The rate of variation of the recycled resin in this calculation example has become even smaller. d The rate of change was 3.1%.

[0146] From calculation examples 1 to 3, the volume fractions of the two types of additive resins to be supplied are calculated based on the viscosity of the recycled resin obtained, and then the volume fractions of the two types of additive resins to be supplied are changed, thereby changing the viscosity η of the recycled resin which is derived from the variation in the viscosity η1 of the recovered resin. d It was found that this can suppress fluctuations.

[0147] Furthermore, by reducing the variation in the viscosity η1 of the recovered resin, the viscosity η of the recycled resin can be reduced. d It was found that the rate of variation also becomes smaller. From this, it can be seen that by increasing the volume of the storage section for the recovered resin or by stirring the recovered resin in the storage section, the variation in the viscosity η1 of the recovered resin can be reduced. d It was found to contribute to the stabilization of [the system].

[0148] [Calculation Example 4] (Example) The mixing time for the recovered resin and added resin in the kneader was set to 300 seconds, and the same simulation as in Calculation Example 1 was performed without changing other conditions. Figure 10 shows the viscosity η1 of the recovered resin at this time and the calculated viscosity η of the recovered resin 300 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0149] Shortening the mixing time of the recovered resin and added resin in the kneader reduces the viscosity of the recycled resin η dThe rate of variation was smaller than in calculation example 1. The viscosity of the recycled resin in this calculation example is η d The rate of change was 7.0%.

[0150] [Calculation Example 5] (Example) The mixing time for the recovered resin and the added resin in the kneader was set to 300 seconds, and the fluctuation period of the viscosity η1 of the recovered resin was set to 240 minutes. A simulation similar to that in Calculation Example 1 was performed, with all other conditions unchanged. Figure 11 shows the viscosity η1 of the recovered resin at this time, and the calculated viscosity η of the recovered resin 300 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0151] Shortening the mixing time of the recovered resin and added resin in the kneader reduces the viscosity of the recycled resin η d The rate of variation became smaller than in calculation example 2. Also, if the variation period of the viscosity η1 of the recovered resin is made longer than in calculation example 4, the viscosity η of the recycled resin d The rate of variation became smaller. Viscosity η of recycled resin in this calculation example d The rate of change was 3.4%.

[0152] [Calculation Example 6] (Example) The mixing time for the recovered resin and the added resin in the kneader was set to 300 seconds, and the fluctuation period of the viscosity η1 of the recovered resin was set to 480 minutes. A simulation similar to that in Calculation Example 1 was performed, with all other conditions unchanged. Figure 12 shows the viscosity η1 of the recovered resin at this time, and the calculated viscosity η1 of the recovered resin 300 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0153] Shortening the mixing time of the recovered resin and added resin in the kneader reduces the viscosity of the recycled resin η dThe rate of variation became smaller than in calculation example 3. Also, if the variation period of the viscosity η1 of the recovered resin is made longer than in calculation example 5, the viscosity η of the recycled resin d The rate of variation of the recycled resin in this calculation example has become even smaller. d The rate of change was 1.6%.

[0154] From calculation examples 4 to 6, by shortening the mixing time of the recovered resin and added resin in the kneader, the viscosity η of the recycled resin can be reduced. d It was found that the rate of variation also decreased. From this, it was found that reducing the volume of the kneader or increasing the flow rate of the resin can reduce the viscosity η of the recycled resin. d It was found to contribute to the stabilization of [the system].

[0155] Furthermore, calculation examples 4 to 6 show that by reducing the variation in the viscosity η1 of the recovered resin, the viscosity η of the recycled resin can be reduced. d It was found that the rate of fluctuation also decreased. From this, it was found that increasing the volume of the storage section for the recovered resin or stirring the recovered resin in the storage section reduces the fluctuation of the viscosity η1 of the recovered resin, and the viscosity η of the recycled resin d It was found to contribute to the stabilization of [the system].

[0156] [Calculation Example 7] (Example) The volume fractions φ1 of the recovered resin supply, φ2 of the second resin supply, and φ3 of the third resin supply were set to φ1=0.3, φ2=0.3, and φ3=0.4, respectively, and a simulation similar to that in Calculation Example 1 was performed without changing any other conditions. Figure 13 shows the viscosity η1 of the recovered resin at this time and the calculated viscosity η of the recovered resin 600 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0157] When the volume fraction φ1 of the amount of recovered resin supplied is reduced, the viscosity η of the recycled resin d The rate of variation was smaller than in calculation example 1. The viscosity of the recycled resin in this calculation example is ηd The rate of change was 8.5%.

[0158] [Calculation Example 8] (Example) The volume fractions φ1 of the recovered resin supply, φ2 of the second resin supply, and φ3 of the third resin supply were set to φ1=0.3, φ2=0.3, and φ3=0.4, respectively. The fluctuation period of the viscosity η1 of the recovered resin was set to 240 minutes. A simulation similar to that in Calculation Example 1 was performed, without changing any other conditions. Figure 14 shows the viscosity η1 of the recovered resin at this time and the calculated viscosity η of the recovered resin 600 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0159] When the volume fraction φ1 of the amount of recovered resin supplied is reduced, the viscosity η of the recycled resin d The rate of variation became smaller than in calculation example 2. Also, if the variation period of the viscosity η1 of the recovered resin is made longer than in calculation example 7, the viscosity η of the recycled resin d The rate of variation became smaller. Viscosity η of recycled resin in this calculation example d The rate of change was 4.2%.

[0160] [Calculation Example 9] (Example) The volume fractions φ1 of the recovered resin supply, φ2 of the second resin supply, and φ3 of the third resin supply were set to φ1=0.3, φ2=0.3, and φ3=0.4, respectively. The fluctuation period of the viscosity η1 of the recovered resin was set to 480 minutes. A simulation similar to that in Calculation Example 1 was performed, without changing any other conditions. Figure 15 shows the viscosity η1 of the recovered resin at this time and the calculated viscosity η of the recovered resin 600 seconds prior. 1-past The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0161] When the volume fraction φ1 of the amount of recovered resin supplied is reduced, the viscosity η of the recycled resind The rate of variation became smaller than in calculation example 3. Also, if the variation period of the viscosity η1 of the recovered resin is made longer than in calculation example 8, the viscosity η of the recycled resin d The rate of variation became smaller. Viscosity η of recycled resin in this calculation example d The rate of change was 1.9%.

[0162] From calculation examples 7 to 9, by making the volume fraction φ1 of the supply amount of recovered resin smaller, the viscosity η of the recycled resin can be reduced. d It was found that the rate of variation of the viscosity η of the recycled resin becomes smaller. From this, it was found that by controlling the volume fraction φ1 of the supply amount of recovered resin, the viscosity η of the recycled resin can be controlled. d It was found that it could be stabilized.

[0163] Furthermore, calculation examples 7 to 9 show that by reducing the variation in the viscosity η1 of the recovered resin, the viscosity η of the recycled resin can be reduced. d It was found that the rate of variation also becomes smaller. From this, it can be seen that by increasing the volume of the storage section for the recovered resin or by stirring the recovered resin in the storage section, the variation in the viscosity η1 of the recovered resin can be reduced. d It was found to contribute to the stabilization of [the system].

[0164] [Calculation Example 10] (Example) The recovered resin, the second resin, and the third resin were kneaded under the conditions of Calculation Example 1. The viscosity of the recycled resin measured was η. d Then, using the volume fraction φ2 of the amount of the second resin supplied 600 seconds ago and the volume fraction φ3 of the amount of the third resin supplied, the viscosity η of the recovered resin supplied 600 seconds ago is calculated using equation (1). 1-past The reverse calculation was performed every 120 seconds starting from the start of resin dispensing (600 seconds after the start of operation). Then, the viscosity η obtained for each was calculated. 1-past Based on the elapsed time at that time, an approximate formula was created to show the change in viscosity η1 of the recovered resin over time. Note that the viscosity η of the recovered resin obtained by reverse calculation over the past 5 times (600 seconds) was also used. 1-past The moving average of the past 600 seconds is smoothed and the moving average of η 1-past This was approximated by the linear equation Y = AX + B (where Y is η1 and X is time (seconds)).

[0165] Using this first-order approximation formula, the viscosity of the recovered resin after 600 seconds (η after 600 seconds) 1-present ) was predicted. Then, according to equation (1), the viscosity η1 of the recovered resin after 600 seconds was the predicted value η. 1-present When this is the case, the viscosity η of the resulting recycled resin d Target viscosity η final To achieve a (2200 Pas) ratio, the volume fractions φ2 of the second resin to be supplied and φ3 of the third resin to be supplied after 600 seconds were calculated. Then, the amounts of the second and third resins corresponding to the calculated volume fractions were supplied after 600 seconds. This control was performed continuously over time, changing the volume fractions φ2 and φ3 of the second resin to be supplied. The linear approximation formula was updated as needed based on η1 over the past 600 seconds.

[0166] Figure 16 shows the viscosity η1 of the recovered resin at this time, and the calculated viscosity η of the recovered resin 600 seconds prior. 1-past , the viscosity of the recovered resin after the predicted 600 seconds η 1-present The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the supply amount of the second resin supplied after the supply amount was changed. Note that in this calculation example, η 1-past and η 1-present These two almost overlap. In Figure 16, of these two calculation results which are shown almost overlapping, the solid line is and the dashed line is η 1-present That is the case.

[0167] Figure 16 shows the viscosity η1 of the recovered resin at this time and the viscosity η of the recovered resin after the predicted 600 seconds. 1-present The viscosity of the recycled resin measured η d This is a simulation result showing the changes in the volume fraction φ2 of the second resin supplied and the volume fraction φ3 of the third resin supplied, as well as the changes in the supply amount of the second resin supplied.

[0168] Predict the viscosity η1 of the recovered resin based on the approximate formula, and change the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin using the predicted values, so as to obtain the viscosity η of the recycled resin d The fluctuation rate of was further reduced. The viscosity η of the recycled resin in this calculation example d The fluctuation rate of was 1.0%.

[0169] From Calculation Example 10, by changing the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin based on the predicted value of the viscosity η1, it was found that the fluctuation rate of the viscosity η of the recycled resin d can be further reduced.

[0170] [Calculation Example 11] (Comparative Example) It was assumed that the recovered resin, the second resin, and the third resin were kneaded under the conditions of Calculation Example 1. Based on the measured viscosity η of the recycled resin d No change was made to the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin, and the supply amounts of the second resin and the third resin were kept constant. Figure 17 shows the viscosity η1 of the recovered resin at this time, the viscosity η of the recovered resin 600 seconds before calculation 1-past , the measured viscosity η of the recycled resin d , as well as the simulation results showing the changes in the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin supplied with the supply amount changed.

[0171] The fluctuation rate of the viscosity ηd of the recycled resin in this calculation example was 23.0%.

[0172] [Calculation Example 12] (Comparative Example) The volume fraction φ1 of the supply amount of the recovered resin, the volume fraction φ2 of the supply amount of the second resin, and the volume fraction φ3 of the supply amount of the third resin were set to φ1 = 0.5, φ2 = 0.2, and φ3 = 0.3. The measured viscosity η of the recycled resin dBased on this, the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin were not changed, and the supply amounts of the second resin and the third resin were made constant. Without changing other conditions, a simulation similar to Calculation Example 1 was performed. FIG. 18 shows the viscosity η1 of the recovered resin at this time, the viscosity η of the recovered resin 600 seconds before calculation 1-past , the measured viscosity η of the regenerated resin d , and the simulation results showing the change in the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin supplied with the supply amount changed.

[0173] The fluctuation rate of the viscosity ηd of the regenerated resin in this calculation example was 26.9%.

[0174] [Calculation Example 13] (Comparative Example) The volume fraction φ1 of the supply amount of the recovered resin, the volume fraction φ2 of the supply amount of the second resin, and the volume fraction φ3 of the supply amount of the third resin were set to φ1 = 0.3, φ2 = 0.3, and φ3 = 0.4. Based on the measured viscosity η of the regenerated resin d , the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin were not changed, and the supply amounts of the second resin and the third resin were made constant. Without changing other conditions, a simulation similar to Calculation Example 1 was performed. FIG. 19 shows the viscosity η1 of the recovered resin at this time, the viscosity η of the recovered resin 600 seconds before calculation 1-past , the measured viscosity η of the regenerated resin d , and the simulation results showing the change in the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin supplied with the supply amount changed.

[0175] The fluctuation rate of the viscosity ηd of the regenerated resin in this calculation example was 16.7%.

[0176] From Calculation Examples 11 to 13, it was found that if the volume fraction φ2 of the supply amount of the second resin and the volume fraction φ3 of the supply amount of the third resin were not changed based on the measured viscosity η of the regenerated resin d , the fluctuation rate of the viscosity η of the regenerated resin d did not decrease significantly.

[0177] This application claims priority to Japanese Patent Application No. 2022-138078, filed on 31 August 2022. The matters described in the original specification, claims and drawings of said application are incorporated herein by reference. [Industrial applicability]

[0178] According to the kneading apparatus of the present invention, when adding an additive resin to recovered resin to obtain recycled resin with uniform viscosity, the uniformity of the viscosity of the resulting recycled resin can be achieved using only one kneader. The kneading apparatus of the present invention can uniformize the viscosity of recycled resin obtained from consumer materials and off-grade materials, and regenerate them into recycled resin that is easy to use in a variety of applications. Therefore, it is expected to broaden the range of reuse of these resins and contribute to improving the efficiency of resin recycling. Furthermore, by using only one kneader, it is expected that space saving will be possible, making the production of recycled resin easier. [Explanation of symbols]

[0179] 100 Mixing device 110 Mixing machine 111 Cylinder 112 Screw 113 Hopper 114 Storage section 114a Stirrer 115 Hopper 115a 2nd resin supply section 115b 3rd resin supply section 116 Extrusion section 117 Resin channel 120 Viscometer 130 Control Unit 132 CPU 134 RAM 136 ROM 138 Memory section 142 Input / Output Interfaces

Claims

1. The process of supplying the recovered resin to the kneader, A step of supplying two or more additive resins with different viscosities to the kneader, A step of kneading the recovered resin and the two or more additive resins to obtain a recycled resin, After the start of the kneading, the step of measuring the viscosity of the kneaded resin or the recycled resin obtained by kneading, A step of changing the supply amount of each of the two or more additive resins based on the measured viscosity, A method for producing recycled resin having the following characteristics.

2. A method for producing recycled resin according to claim 1, wherein the degree of stirring before supplying the recovered resin is changed based on the measured viscosity.

3. A method for producing recycled resin according to claim 1 or 2, wherein the kneading time between the recovered resin and the two or more additive resins in the kneader is changed based on the measured viscosity.

4. The process includes a step of calculating the viscosity of the supplied recovered resin from the measured viscosity, The step of changing the supply amount is a step of changing the supply amount of each of the two or more additive resins to the supply amount determined based on the viscosity of the recovered resin calculated above. A method for producing recycled resin according to claim 1 or 2.

5. The method for producing recycled resin according to claim 1 or 2, wherein the mixing time between the recovered resin and the two or more additive resins in the kneader is 3 minutes or more and 30 minutes or less.

6. The recycled resin comprises at least one resin selected from the group consisting of polyethylene, polypropylene, polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), polycarbonate, and polyester. A method for producing recycled resin as described in 1 or 2.

7. The two or more additive resins mentioned above are: A second resin with a smaller melt flow rate, A third resin with a higher melt flow rate, The melt flow rate (MFR) of the second resin and the third resin, as measured in accordance with ASTM D1238 (2013), is both between 1 g / 10 min and 300 g / 10 min. A method for producing recycled resin as described in 1 or 2.

8. The ratio of the melt flow rate of the second resin to the melt flow rate of the third resin (MFR of the second resin / MFR of the third resin), measured under the same conditions, is between 2 and 100. A method for producing recycled resin according to claim 7.

9. The method for producing recycled resin according to claim 1 or 2, wherein the amount of the recovered resin supplied is 10% by volume or more and 70% by volume or less of the total volume of the recycled resin.

10. A cylinder having a screw, A first supply unit that supplies the recovered resin to the cylinder, It has a second supply unit that supplies two or more additive resins with different viscosities to the cylinder, A kneader for kneading the recovered resin and the two or more additive resins inside the cylinder, A viscometer for measuring the viscosity of the resin being kneaded by the aforementioned kneader, or the recycled resin obtained by kneading with the kneader, A control unit that changes the supply amount of each of the two or more additive resins from the second supply unit based on the viscosity measured by the viscometer, A manufacturing apparatus for recycled resin, having the following features.

11. The first supply unit has a storage unit for storing the recovered resin supplied to the cylinder, The storage unit has a stirrer for stirring the recovered resin. The apparatus for manufacturing recycled resin according to claim 10.

12. The apparatus for manufacturing recycled resin according to claim 11, wherein the storage section has a volume larger than the capacity of the cylinder.

13. The apparatus for manufacturing recycled resin according to claim 11, wherein the capacity of the storage section is five times or more the capacity of the cylinder.

14. The apparatus for producing recycled resin according to claim 11, wherein the control unit changes the degree of stirring of the recovered resin by the stirrer based on the viscosity measured by the viscometer.

15. The apparatus for producing recycled resin according to claim 10, wherein the control unit changes the mixing time of the recovered resin and the two or more additive resins inside the cylinder based on the viscosity measured by the viscometer.

16. The apparatus for manufacturing recycled resin according to claim 10, wherein the control unit calculates the viscosity of the supplied recovered resin from the measured viscosity, and changes the supply amount of each of the two or more additive resins to the supply amount determined based on the calculated viscosity of the recovered resin.

17. The control unit calculates the viscosity of the supplied recovered resin from the measured viscosity, and uses the calculated viscosity of the recovered resin and the state of the recovered resin at the time of recovery as training data to generate an estimation model by machine learning that estimates the viscosity of the recovered resin predicted from the state of recovery. A apparatus for producing recycled resin according to any one of claims 10 to 16.

18. The apparatus for manufacturing recycled resin according to claim 10, wherein the screw has a ratio (L / D) of length (L) to diameter (D) of 20 or more and 80 or less.

19. When producing recycled resin by adding recovered resin and two or more types of additive resins with different viscosities to the same kneader and kneading them, a computer determines the supply amount of the two or more types of additive resins. The system accepts viscosity data measured from the kneaded resin or the recycled resin obtained by kneading, Based on the amount of the recovered resin used in the production of the resin or recycled resin whose viscosity has been measured, the amount of each of the two or more additive resins supplied, and the viscosity of each of the two or more additive resins, the amount of each of the two or more additive resins supplied is determined such that the viscosity of the resin or recycled resin whose viscosity has been measured becomes the target viscosity. A program that executes the command.

20. When determining the supply quantity, Based on the viscosity data received, the viscosity of the recovered resin is calculated, Based on the viscosity of the recovered resin calculated above, the supply amount of each of the two or more additive resins is determined, The program according to claim 19, which causes the computer to execute the program.

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