Kneading apparatus

Abstract

To provide a kneading apparatus capable of obtaining a regenerated resin having a predetermined viscosity from a collected resin while suppressing addition of an impurity.SOLUTION: A kneading apparatus according to the present invention has a second kneader for introducing and kneading a second resin and a third resin into a first resin kneaded by a first kneader. The second kneader allows an introduced amount of the second resin and an introduced amount of the third resin to vary in accordance with a viscosity of the first resin kneaded by the first kneader.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a kneading device.

Background Art

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

[0003]

[0004] For example, Patent Document 1 describes a granulator having an extruder that melts and kneads waste plastic materials and extrudes them, and a molding device that granulates the molten plastic extruded by the extruder into pellets.

Prior Art Documents

Patent Documents

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

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

[0007] In view of the above problems, an object of the present invention is to provide a kneading device that can obtain a recycled resin having a predetermined viscosity from a recovered resin while suppressing the addition of impurities. Means for Solving the Problems

[0008] A kneading device according to an aspect of the present invention for solving the above problems includes a second kneading machine that inputs and kneads a second resin into the first resin kneaded by the first kneading machine. The second kneading machine changes the input amount of the second resin according to the viscosity of the first resin kneaded by the first kneading machine.

[0009] Further, a kneading device according to another aspect of the present invention for solving the above problems includes a second kneading machine that inputs and kneads a second resin and a third resin into the first resin kneaded by the first kneading machine. The second kneading machine changes the ratio of the input amount of the second resin to the input amount of the third resin according to the viscosity of the kneaded product extruded from the second kneading machine. Advantages of the Invention

[0010] According to the present invention, there is provided a kneading device that can obtain a recycled resin having a predetermined viscosity from a recovered resin while suppressing the addition of impurities. Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0012] Hereinafter, the kneading apparatus of the present invention will be described with reference to a plurality of embodiments.

[0013] [First Embodiment] Figure 1 is a schematic diagram showing the configuration of a kneading apparatus 100 according to a first embodiment of the present invention. The kneading apparatus 100 is a kneading apparatus for melting and kneading recycled resin to regenerate it into recycled resin having a predetermined viscosity.

[0014] The above-mentioned recycled resin is typically a resin component recovered from waste products, a resin component that is inevitably produced in the manufacturing process but does not become a final product, and the like. These recycled resins contain various resin species in different ratios, contain metals other than resin, or contain additives such as pigments and release agents. After being crushed, the above-mentioned recycled resin is subjected to removal of metal components such as iron by magnetic separation and separated for each resin species by specific gravity separation. However, it is almost impossible to completely separate each component even by these treatments.

[0015] For example, the recovered resin recovered from discarded automobiles contains a mixture such as polyethylene, polypropylene, polyamide, and polyurethane in the resin component after removing the metal component. If specific gravity separation is performed on these resin components, it is possible to separate the mixture of polyethylene and polypropylene from polyamide. However, it is not practical to separate polyethylene and polypropylene by specific gravity separation from the viewpoints of time and cost. And the ratio of polyethylene and polypropylene varies depending on the type and parts of the automobile.

[0016] Therefore, if the recovered resin recovered from the above-discarded automobiles is directly melt-kneaded, the ratios of polyethylene and polypropylene in the obtained recycled resin will vary. And depending on the above ratios, the viscosity and fluidity of the obtained recycled resin also change. Due to the unpredictability of these viscosities and fluidities, it is very difficult to directly reuse the obtained recycled resin.

[0017] The kneading device 100 regenerates a recycled resin having a predetermined viscosity by melt-kneading such recovered resin and further mixing and melt-kneading other resins.

[0018] The kneading device 100 is a tandem-type extruder having a first kneader 110 and a second kneader 120 connected to the downstream side of the first kneader 110. A viscometer 130 for in-line measuring the viscosity of the recovered resin kneaded by the first kneader 110 is arranged at a position which is the rear stage of the first kneader 110 and the front stage of the second kneader 120.

[0019] The first kneader 110 is a kneader (extruder) for melt-kneading the recovered resin.

[0020] The first kneader 110 has a long cylindrical cylinder 112, a screw 114 rotatably arranged in the inner hole of the cylinder 112, a hopper 116 for charging the recovered resin into the cylinder 112, and an extrusion part 118 for extruding the kneaded recovered resin.

[0021] The cylinder 112 is a container for kneading the recycled resin introduced therein with the screw 114. The cylinder 112 may have a heating unit for adjusting the internal temperature to melt the recycled resin.

[0022] One or more screws 114 are arranged inside the cylinder 112 and rotated by a motor (not shown) to knead the recycled resin in the cylinder 112. A twin-screw extruder composed of two screws can adjust the kneading characteristics as a combination of screw segments having various kneading characteristics such as forward flights, kneading, and reverse flights, and thus can be appropriately selected according to the type of resin and its physical properties. Furthermore, an extruder composed of a plurality of screw shafts can also be appropriately selected according to the kneading performance.

[0023] The hopper 116 is an inlet for introducing the recycled resin into the interior of the cylinder 112. In the present embodiment, the hopper 116 introduces into the interior of the cylinder 112 the recycled resin containing polyethylene and polypropylene, which has been recovered from discarded automobiles, crushed, and separated by magnetic separation and specific gravity separation.

[0024] The extrusion unit 118 communicates with one end of the resin flow path 140 and extrudes the recycled resin that has been introduced into the interior of the cylinder 112 and melt-kneaded by the rotation of the screw 114 into the resin flow path 140 that communicates with the second kneader 120. The extrusion unit 118 can be a known gear pump or the like.

[0025] The second kneader 120 is a kneader (extruder) for adjusting the viscosity of the obtained recycled resin to a predetermined range by adding another resin (hereinafter simply referred to as "additive resin") to the recycled resin kneaded by the first kneader 110 and further melt-kneading it.

[0026] Specifically, the second kneader 120 includes a long cylindrical cylinder 122, a screw 124 rotatably disposed in the inner hole of the cylinder 122, an inlet 126 for introducing the recycled resin melt-kneaded by the first kneader 110 into the cylinder 122, a hopper 127a for charging the additive resin into the cylinder 122, a hopper 127b for charging additives such as rubber and talc into the cylinder 122, and an extrusion section 128 for extruding the kneaded recycled resin.

[0027] The cylinder 122 is a container for kneading the resin components introduced therein with the screw 124. The cylinder 122 may have a heating section for adjusting the internal temperature to melt the resin components.

[0028] One or more screws 124 are arranged inside the cylinder 122 and rotated by a motor (not shown) to knead the resin components in the cylinder 122. A twin-screw extruder composed of two screws can adjust the kneading characteristics as a combination of screw segments with various kneading characteristics such as forward flights, kneading, and reverse flights, and thus can be appropriately selected according to the type of resin and its physical properties. Furthermore, an extruder composed of a plurality of screw shafts can also be appropriately selected according to the kneading performance.

[0029] The inlet 126 communicates with the other end of the resin flow path 140 and introduces the recycled resin melt-kneaded by the first kneader 110 and extruded from the extrusion section 118 from the resin flow path 140 into the interior of the cylinder 122 of the second kneader 120.

[0030] The hopper 127a is an inlet for charging the additive resin into the interior of the cylinder 122. The additive resin is a resin with a known viscosity and is a resin for adjusting the viscosity of the recycled resin to a predetermined range by being added to and mixed with the recycled resin. The additive resin may be the same type of resin as the recycled resin (polyethylene or polypropylene in this embodiment) or a different type of resin from the recycled resin.

[0031] Hopper 127a changes the input amount of the additive resin according to the viscosity of the recovered resin measured by the viscometer 130. Control for changing the input amount of the additive resin from Hopper 127a will be described later.

[0032] Hopper 127b is an inlet for injecting additives such as stabilizers, antioxidants, and crystal nucleating agents, and fillers such as rubber, talc, and calcium carbonate into the cylinder 122. Also, reinforcing fiber materials such as glass fiber, carbon fiber, and organic fiber can be added. The addition of these fillers and reinforcing fibers greatly affects the viscosity. However, the viscosity of the resin at the time of addition is uniformly controlled. Even if a certain amount of filler and reinforcing fiber is added, the change in viscosity due to the addition is within a range that can be predicted by theoretical formulas, empirical formulas, etc. Therefore, the addition of these additives does not make the viscosity of the resulting recycled resin unpredictable.

[0033] The extrusion section 128 has a die, etc., and extrudes the recycled resin having a predetermined viscosity that has been melt-kneaded by the first kneader 110 and the second kneader 120.

[0034] The viscometer 130 is an in-line viscometer and measures the viscosity of the recovered resin melt-kneaded by the first kneader. The viscometer 130 may be any known viscometer that measures the viscosity by taking out a part of the recovered resin that has been melt-kneaded by the first kneader 110 and moving to the second kneader. For example, devices for measuring viscosity in-line are introduced in R. Gendron, L. E. Daigneault, J. Cell. Plast., 35, 221 (1999). and M. Lee, C. B. Park, C. Tzoganakis, Polym. Eng. Sci., 39, 99 (1999).

[0035] The resin flow path 140 is a flow path that communicates between the first kneader 110 and the second kneader 120, and has a diameter and structure that allows the recovered resin melted and kneaded in the first kneader 110 to flow through it. The resin flow path 140 may have a valve (not shown) for controlling the movement of the melted and kneaded recovered resin from the first kneader 110 to the second kneader 120. The resin flow path 140 may also have a heating section (not shown) for heating the recovered resin moving inside to maintain its fluidity.

[0036] In this embodiment, the hopper 127a changes the amount of added resin depending on the viscosity of the recovered resin melted and kneaded in the first kneader 110 measured by the viscometer 130 (in this specification, "viscosity" means melt viscosity).

[0037] Specifically, in this embodiment, the hopper 127a is configured to calculate the volume fraction φ of the recovered resin relative to the total volume of the recovered resin introduced into the second kneader 120 and the volume of the added resin charged into the second kneader 120 (hereinafter, simply referred to as the "total volume of the resin components charged into the second kneader") based on theories regarding polymer blending, such as the Double-Reptation theory (C. Tsenoglou, Macromolecules, 24, 1762-1767 (1991)). i and viscosity η i , and the viscosity η of the added resin j The viscosity is calculated from η Blend The volume fraction φ of the added resin to the total volume of the resin components fed into the second kneader to obtain a recycled resin having a volume fraction of φ j , an amount of additive resin corresponding to the amount of resin to be added is poured into the cylinder 122.

[0038] According to the double-reptation theory, in a two-component system such as the present embodiment, the viscosity η of a mixture of a first resin and a second resin is Blend can be expressed by the following equation (1).

[0039]

number

[0040] In the formula (1), φ 1 represents the volume fraction of the first resin (recovered resin in this embodiment) with respect to the total volume of the resin components introduced into the second kneader, and η 1 represents the viscosity of the first resin, and φ 2 represents the volume fraction of the second resin (added resin in this embodiment) with respect to the total volume of the resin components introduced into the second kneader, and η 2 represents the viscosity of the second resin, and η Blend represents the viscosity of the resulting mixture.

[0041] Here, the viscosity η 1 of the first resin is the viscosity of the recovered resin kneaded in the first kneader measured by the viscometer 130. Also, the viscosity η 2 (viscosity of the added resin) of the second resin is known. In the formula (1), the unknown values are φ 1 and φ 2 . However, since φ 1 and φ 2 are φ 1 +φ 2 = 1 in this embodiment, φ 2 can be read as 1 - φ 1 . That is, the unknown value in the formula (2) is only φ 2 .

[0042] Therefore, by substituting these values and the value of the viscosity η Blend of the recycled resin to be obtained into the formula (1), the volume fraction φ 2 of the added resin to be introduced into the second kneader 120 can be calculated. And the actual volume V 1 of the first resin can be obtained from the rotation speed of the gear pump of the extrusion part 218 attached to the first kneader 110. Therefore, the volume V 2 of the second resin (added resin) to be introduced into the second kneader 120 from the hopper 127a is V 1 ×(φ 2 / φ 1) can be calculated by. Since the viscosity of the resin depends on the shear rate, select the viscosity corresponding to the shear rate condition of the in-line viscosity measurement. As another method, by introducing models representing the shear rate dependence of the resin viscosity (such as the Cross equation, Bird-Carreau equation, Carreau-Yasuda equation, etc.) into Equation (1) and expanding it, the accuracy of viscosity control can be improved.

[0043] For example, the viscosity η of the second resin (additive resin) 2 is 5.5×10 4 Pa·s, and assume that the viscosity η of the first resin (recovered resin kneaded by the first kneader) measured by the viscometer 130 1 is each of the numerical values described in Table 1. At this time, if it is desired to obtain a recycled resin with a viscosity η Blend of 3.0×10 4 Pa·s, the hopper 127a should determine the input amount of the additive resin into the cylinder 122 so that the volume fraction φ 1 of the first resin (recovered resin) and the volume fraction φ 2 of the second resin (additive resin) are in the following ratio.

[0044]

Table 1

[0045] As described above, according to the first embodiment, the viscosity of the obtained recycled resin can be adjusted to a predetermined range only by changing the input amount of the additive resin input into the second kneader. Therefore, it is not necessary to add impurities, and it is difficult for unpredictable changes to occur in the physical properties of the obtained recycled resin. In addition, the method of adjusting the MFR of the recycled resin by adjusting the input amount of additives other than the resin as described in Patent Document 1 may not be applicable depending on the type of the recovered resin. For example, the molecular weight of polypropylene decreases due to molecular chain scission by peroxide, and the MFR increases, while polyethylene crosslinks by peroxide, the molecular weight increases, and the MFR decreases. In contrast, in the present invention, it is possible to equalize the viscosity of the recycled resin even in a mixture of waste plastics in which polypropylene and polyethylene may be mixed.

[0046] [Second Embodiment] FIG. 2 is a schematic diagram showing the configuration of a kneading apparatus 200 according to the second embodiment of the present invention. The kneading apparatus 200 is also a kneading apparatus for melting and kneading the recovered resin to regenerate it into a recycled resin having a predetermined viscosity.

[0047] The kneading apparatus 200 is a tandem type extruder having, similarly to the kneading apparatus 100 according to the first embodiment, a first kneader 210 and a second kneader 220 connected to the downstream side of the first kneader 210. A viscometer 230 for in-line measuring the viscosity of the recovered resin kneaded by the first kneader 210 is installed at the connection portion between the first kneader 210 and the second kneader 220.

[0048] The first kneader 210 includes a long cylindrical cylinder 212, a screw 214 rotatably disposed in the inner bore of the cylinder 212, a hopper 216 for charging recycled resin into the cylinder 212, and an extrusion section 218 for extruding the kneaded recycled resin. Since these configurations and functions are the same as those of the cylinder 112, screw 114, hopper 116, and extrusion section 118 of the first kneader 110 in the first embodiment, duplicate explanations are omitted. In this embodiment as well, the hopper 216 feeds into the interior of the cylinder 212 the recycled resin containing polyethylene and polypropylene, which has been recovered from discarded automobiles, crushed, and separated by magnetic separation and specific gravity separation.

[0049] The second kneader 220 includes a long cylindrical cylinder 222, a screw 224 rotatably disposed in the inner bore of the cylinder 222, an inlet 226 for introducing the recycled resin melt-kneaded by the first kneader 210 into the cylinder 222, a hopper 227a for charging additive resin into the cylinder 222, a hopper 227b for charging additives such as rubber and talc into the cylinder 222, and an extrusion section 228 for extruding the kneaded recycled resin. Since the configurations and functions of these cylinder 212, screw 214, hopper 227b, and extrusion section 218 are the same as those of the cylinder 212, screw 214, hopper 227b, and extrusion section 218 of the second kneader 120 in the first embodiment, duplicate explanations are omitted.

[0050] The viscometer 230 is an in-line viscometer and measures the viscosity of the recycled resin melt-kneaded by the first kneader. The resin flow path 240 is a flow path that communicates the first kneader 210 and the second kneader 220 and has a diameter and structure through which the recycled resin melt-kneaded by the first kneader 210 can flow. Since the configurations and functions of the viscometer 230 and the resin flow path 240 are the same as those of the viscometer 130 and the resin flow path 140 in the first embodiment, duplicate explanations are omitted.

[0051] The kneading apparatus 200 according to this embodiment is different from the kneading apparatus 100 according to the first embodiment in that the hopper 227a of the second kneader 220 inputs two types of additive resins having different viscosities into the cylinder 222. And the hopper 227a can independently change the input amount of each of the two types of additive resins. Note that one of the two types of resins (hereinafter simply referred to as the "first additive resin") is a resin having a viscosity higher than the viscosity of the recycled resin to be obtained, and the other resin (hereinafter simply referred to as the "second additive resin") is a resin having a viscosity lower than the viscosity of the recycled resin to be obtained.

[0052] In the kneading apparatus 200 according to this embodiment, the hopper 227a changes the input amounts of the first additive resin and the second additive resin according to the viscosity of the recovered resin melt-kneaded by the first kneader 210, which is measured by the viscometer 230.

[0053] According to the Double-Reptation theory, in a three-component system such as this embodiment, the viscosity η of the mixture of the first resin, the second resin, and the third resin Blend can be expressed by the following formula (1).

[0054]

Equation

[0055] In Equation (2), φ 1 represents the volume fraction of the first resin (in this embodiment, the recovered resin) with respect to the total amount of the volume of the recovered resin introduced into the second kneader 220, the volume of the first additive resin input into the second kneader 220, and the volume of the second additive resin input into the second kneader 220 (the total volume of the resin components input into the second kneader), η 1 represents the viscosity of the first resin, φ 2 represents the volume fraction of the second resin (in this embodiment, the first additive resin) with respect to the total volume of the resin components input into the second kneader, η 2 represents the viscosity of the second resin, φ 3represents the volume fraction of the third resin (the second added resin in this embodiment) with respect to the total volume of the resin components input into the second kneader, and is η 3 represents the viscosity of the third resin, and is η Blend represents the viscosity of the resulting mixture.

[0056] Also in this embodiment, the viscosity η of the first resin 1 is the viscosity of the recovered resin kneaded in the first kneader, which is measured by the viscometer 230. Also, the viscosity η of the second resin (the first added resin) 2 and the viscosity η of the third resin (the second added resin) 3 are known.

[0057] Also, in this embodiment, the volume fraction φ of the first resin 1 can be obtained from the amount of the recovered resin input from the hopper 216 into the first kneader 210 and the amount of the recycled resin to be obtained.

[0058] In Equation (2), the unknown values are φ 2 and φ 3 However, since φ 1 , φ 2 , and φ 3 are φ 1 + φ 2 + φ 3 = 1 in this embodiment, φ 3 can be rewritten as 1 - φ 1 - φ 2 That is, the unknown value in Equation (2) is only φ 2 .

[0059] Therefore, by substituting these values and the value of the viscosity η of the recycled resin to be obtained into Equation (2), the volume fraction φ of the first added resin (the second resin) to be input into the second kneader 220 Blend can be calculated, and from the calculated value of φ 2 , the volume fraction φ of the first added resin (the third resin) to be input into the second kneader 220 2 3 can be calculated.

[0060] ​ Furthermore, in this embodiment, by specifying the content ratio of the recovered resin in the recycled resin to be obtained, the volume of the obtained recycled resin can be adjusted within a predetermined range.

[0061] As described above, in this embodiment, the recovered resin containing polyethylene and polypropylene is melt-kneaded. Such a mixture of resins of different types is more likely to cause a strength reduction due to phase separation between different resins as compared with a mixture of the same type of resins. Therefore, the ratio of the recovered resin in the recycled resin obtained by melt-kneading is preferably about 30% or less even if it is high. Also, a compatibilizer such as a copolymer of polyethylene and polypropylene can be introduced into the first kneader together with the recovered resin to make phase separation less likely to occur. At this time, furthermore, by using two types of added resins (the second resin and the third resin) as the same type of resin (for example, both polyethylene or both polypropylene), it is also possible to make it less likely to cause a strength reduction due to phase separation between the different resins.

[0062] In such a case, when the volume fraction of the recovered resin (the first resin) is set to a predetermined value (for example, 30%), the total amount of the volume fraction of the first added resin (the second resin) added by the second kneader and the volume fraction of the second added resin (the third resin) is also determined (for example, 70%). Then, if the amount (volume) of the recovered resin introduced into the second kneader 220 is made constant, the total amount of the amount (volume) of the first added resin and the amount (volume) of the second added resin to be input into the second kneader 220 also becomes constant (volume of the recovered resin × (70 / 30)). In this embodiment, in this way, the total amount of the amount (volume) of the recovered resin introduced into the second kneader 220, the amount (volume) of the first added resin input into the second kneader 220, and the amount (volume) of the second added resin input into the second kneader 220 can be set within a predetermined range, and thereby the amount (volume) of the obtained recycled resin can also be set within a predetermined range.

[0063] Furthermore, by multiplying the volume fraction of the addition amounts of the second resin (first additive resin) and the third resin (second additive resin) for obtaining the recycled resin having a predetermined viscosity, which is determined in this embodiment, by the total amount of the volume fraction of the additive resins added by the second kneader, the amount (volume) of the first additive resin and the amount (volume) of the second additive resin to be added by the second kneader can be calculated.

[0064] Thus, according to this embodiment, by setting the ratio of the recovered resin contained in the obtained recycled resin and the viscosity of the recycled resin, the amount (volume) of the obtained recycled resin can be within a predetermined range, and the viscosity of the recycled resin can also be within a predetermined range.

[0065] Specifically, let the viscosity η of the second resin (first additive resin) 2 be 2.0×10 5 Pa·s, and the viscosity η of the third resin (second additive resin) 3 be 6.0×10 3 Pa·s, and assume that the viscosity η of the recovered resin kneaded by the first kneader, which is measured by the viscometer 230, is each of the numerical values described in Table 1. At this time, if it is desired to obtain a recycled resin in which the content rate of the recovered resin (corresponding to φ 1 ) is 30% and the viscosity η 1 is 3.0×10 Blend Pa·s, the hopper 227a may change the input amounts of the second resin (first additive resin) and the third resin (second additive resin) input into the cylinder 222 so that the volume fraction φ 4 of the second resin (first additive resin) and the volume fraction φ 2 of the third resin (second additive resin) are in the following ratio. 3 That is, the input amounts of the second resin (first additive resin) and the third resin (second additive resin) input into the cylinder 222 may be changed so that the volume fraction φ

[0066]

Table 2

[0067] As is clear from Table 2, according to the present embodiment, when attempting to obtain a recycled resin in which the content of the recovered resin is within a predetermined range, by only adjusting the ratio of the volume of the first added resin to the volume of the first added resin that the hopper 227a inputs into the inside of the cylinder 122, a recycled resin having a predetermined viscosity can be obtained.

[0068] Thus, according to the second embodiment described above, by only changing the ratio of the volume of the first added resin to the volume of the second added resin input into the second kneader, the viscosity of the obtained recycled resin can be adjusted within a predetermined range. Therefore, the addition of impurities is unnecessary, and unexpected changes are less likely to occur in the physical properties of the obtained recycled resin. Also, if the amount of the recovered resin input into the first kneader and the content of the recovered resin in the obtained recycled resin are set, by only changing the ratio of the volume of the first added resin to the volume of the second added resin input into the second kneader, both the viscosity and the volume of the obtained recycled resin can be within a predetermined range.

[0069] [Third Embodiment] FIG. 3 is a schematic diagram showing the configuration of a kneading device 300 according to the third embodiment of the present invention.

[0070] The kneading device is different from the kneading device 100 according to the first embodiment in that it has a spectroscopic device 350 for measuring the infrared spectroscopic spectrum of the recovered resin melt-kneaded by the first kneader 110. Since the other configurations are the same as those of the first embodiment, duplicate explanations are omitted.

[0071] The spectroscopic device 350 may be a dispersive device or a Fourier transform (FT-IR) type device, but it is preferably an FT-IR type device. The spectroscopic device 350 is preferably one that can measure at high speed so that in-line measurement can be performed, such as the "ParticleTrack with FBRM technology" manufactured by Yamato Scientific Co., Ltd. The spectroscopic device 350 may be a device that attaches an optical fiber 352, for example, to the downstream side of the extrusion section 118 (near the viscometer 130, the resin flow path 140, etc.) and measures the infrared spectroscopic spectrum of the recovered resin at that site.

[0072] As heat stabilizers for polyethylene and polypropylene resins, hindered phenol antioxidants are generally used. For example, in the case of Irganox1010, which is a hindered phenol antioxidant, the stretching vibration of C-O is observed at 1300 - 1000 cm -1 in the IR spectrum, and the stretching vibration of C=O is observed at 1750 - 1735 cm -1 in the IR spectrum. When the above antioxidant ignited during the production of the recovered resin is consumed due to thermal degradation during use, etc., these characteristic peaks in the IR spectrum measured in-line become smaller or disappear. Therefore, by changing the input amount of the heat stabilizer input from the hopper 127b of the second kneader according to the height of the peak of the IR spectrum caused by the heat stabilizer measured by the spectroscopic device 350, the amount of the heat stabilizer in the obtained recycled resin can be adjusted to a constant value. Note that the amount of the heat stabilizer to be input can be determined based on a calibration curve of the height of the peak of the IR spectrum and the addition amount prepared in advance. Alternatively, the amount of the heat stabilizer to be input may be changed based on an empirical formula.

[0073] Note that the additive whose addition amount is changed is not limited to the heat stabilizer, and any type of additive can be used.

[0074] In the above description, an example in which the kneading apparatus 100 according to the first embodiment includes the spectroscopic apparatus 350 has been shown. However, the kneading apparatus 200 according to the second embodiment may include the spectroscopic apparatus 350.

[0075] [Other Embodiments] Note 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.

[0076] For example, in each of the above-described embodiments, the viscosity of the melt-kneaded recycled resin has been measured by the viscometer installed downstream of the first kneader. However, the viscometer may be disposed inside the first kneader, or may be disposed in the resin flow path connecting the first kneader and the second kneader. Further, the viscometer may be configured to measure the pressure and flow rate of the recycled resin extruded from the extrusion part of the first kneader, and calculate the viscosity of the recycled resin from these values.

[0077] In each of the above-described embodiments, the additive resin that is polyethylene or polypropylene has been added to the recycled resin containing polyethylene and polypropylene. However, resin types such as polyethylene alone, polypropylene alone, and polyester alone are not limited to these, but may be off-grade materials or separated and sorted recycled materials. In the present invention, the recycled resin and the additive resin may be a combination of various resins including polyamide, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), polycarbonate, polyurethane, and polyester.

[0078] In the second embodiment, two types of additive resins have been added to the recycled resin melt-kneaded by the first kneader by the second kneader. However, three or more types of additive resins may be added by the second kneader. Further, additives such as stabilizers, antioxidants, and crystal nucleating agents, fillers such as rubber, talc, and calcium carbonate, and reinforcing fiber materials such as glass fiber, carbon fiber, and organic fiber can also be added to the second kneader.

[0079] In addition, in each of the above-described embodiments, recycled resin was added to the first kneader. However, not only recycled resin but also virgin material may be added to the first kneader, or natural resin with an unknown viscosity may be added to the first kneader. Further, as a compatibilizer such as a copolymer of polyethylene and polypropylene, liquid ethylene-propylene rubber, pelletized ethylene-propylene rubber, ethylene-butene rubber, propylene-butene rubber, or propylene-butene-ethylene rubber may be added to the first kneader.

[0080] In addition, in each of the above-described embodiments, the extrusion part of the second kneader may extrude the recycled resin into any known shape including a sheet shape, a film shape, a rod shape, a plate shape, a pipe shape, a shaped cross-section molded product, and a strand shape. Further, a cutter or the like may be arranged at the subsequent stage of the extrusion part to process the extruded recycled resin into a pellet shape. Alternatively, a known molding machine may be arranged at the subsequent stage of the extrusion part to mold the extruded recycled resin into a predetermined shape.

[0081] In addition, in the third embodiment described above, in addition to changing the amount or ratio of the additive resin introduced from the hopper 127a or the hopper 227a, the amount of the additive introduced from the hopper 127b or the hopper 227b was changed. However, without changing the amount or ratio of the additive resin, only the amount of the additive may be changed according to the infrared absorption spectrum measured by the spectroscopic device.

[0082] In addition, in each of the above-described embodiments, the kneading device may be controlled to perform each of the above-described operations by a control unit (not shown). That is, the control unit controls the operation of the hopper of the first kneader to introduce the recovered resin into the cylinder of the first molding machine from the hopper. Further, the control unit controls the operations of the cylinder and the screw (or motor) of the first kneader to heat and melt the recovered resin introduced into the cylinder and knead it. Further, the control unit controls the operation of the extrusion unit of the first kneader to extrude the melt-kneaded recovered resin from the first kneader and introduce it into the cylinder of the second kneader from the inlet of the second kneader. Further, the control unit controls the operation of the hopper of the second kneader to add one or more types of additive resins and optionally additives into the cylinder of the second kneader. Further, the control unit controls the operations of the cylinder and the screw (or motor) of the second kneader to heat and melt the recovered resin and the additive resin (and additives) introduced into the cylinder and knead them. Further, the control unit controls the operation of the extrusion unit of the second kneader to extrude the melt-kneaded resin component from the second kneader. At this time, the control unit changes the input amount of the additive resin added from the hopper of the second kneader (or the ratio of the input amount of the second additive resin to the input amount of the third additive resin) according to the viscosity of the recovered resin melt-kneaded by the first kneader.

Industrial Applicability

[0083] According to the kneading device of the present invention, a recycled resin having a predetermined viscosity can be obtained from the recovered resin. At this time, since it is not necessary to add a substance that reduces the molecular weight of the resin as in Patent Document 1, it is possible to more easily prevent unnecessary impurities from remaining in the obtained recycled resin. Since the kneading device of the present invention can equalize the viscosity of the recycled resin obtained from consumer materials and off-grade materials and recycle it into a recycled resin that is easy to use for various applications, it is expected to contribute to expanding the range of reuse of these resins and improving the recycling efficiency of the resins.

Explanation of Symbols

[0084] 100, 200, 300 Kneading device 110, 210 First kneader 112, 212 Cylinder 114, 214 Screw 116, 216 Hopper 118, 218 Extrusion section 120, 220 Second kneader 122, 222 Cylinder 124, 224 Screw 126, 226 Inlet 127a, 227a Hopper 127b, 227b Hopper 128, 228 Extrusion section 130, 230 Viscometer 140, 240 Resin flow path 350 Spectroscopic device 352 Optical fiber

Claims

1. a second kneader for introducing a second resin and a third resin into the first resin kneaded by the first kneader and kneading them together; The second kneader changes the input amount of the second resin and the input amount of the third resin depending on the viscosity of the first resin kneaded by the first kneader. Kneading equipment.

2. The second kneader is configured to input, as the second resin, a resin having a higher viscosity than a viscosity of the resin obtained by kneading in the second kneader; As the third resin, a resin having a viscosity lower than that of the resin obtained by kneading in the second kneader is introduced.

2. The kneading device according to claim 1.

3. The first resin is a mixture containing polyethylene and polypropylene.

3. The kneading apparatus according to claim 1 or 2.

4. The kneading device according to any one of claims 1 to 3, further comprising a first kneader for kneading the first resin, and the second kneader is connected downstream of the first kneader.

5. a second kneader for introducing a second resin and a third resin into the first resin kneaded by the first kneader and kneading them; The second kneader changes a ratio between an input amount of the second resin and an input amount of the third resin according to a viscosity of the kneaded product obtained from the first kneader. Kneading equipment.

6. The second kneader is configured to input, as the second resin, a resin having a higher viscosity than a viscosity of the resin obtained by kneading in the second kneader; As the third resin, a resin having a viscosity lower than that of the resin obtained by kneading in the second kneader is introduced. The kneading device according to claim 5.

7. 7. The kneading apparatus according to claim 5, further comprising a first kneader for kneading the first resin, and the second kneader is connected downstream of the first kneader.

8. a spectroscopic device for measuring an infrared spectrum of the first resin kneaded by the first kneader; The second kneader changes the amount of additive added depending on the infrared spectrum of the first resin measured by the spectroscopic device. The kneading device according to any one of claims 1 to 7.

9. a second kneader that adds a second resin and an additive to the first resin kneaded by the first kneader and kneads them; a spectrometer for measuring an infrared spectrum of the first resin kneaded by the first kneader; having The second kneader changes the amount of additive added depending on the infrared spectrum of the first resin measured by the spectroscopic device. Kneading equipment.

Images