Mixing Equipment

Abstract

To provide a kneading device capable of obtaining a recycled resin having a predetermined viscosity from a recovered resin while suppressing addition of impurities.SOLUTION: A first kneading device of the present invention has a second kneader in which a second resin is put into a first resin kneaded by a first kneader and is kneaded, and the second kneader causes to change an input amount of the second resin according to the viscosity of the first resin kneaded by the first kneader. The second kneading device of the present invention has a second kneading machine in which the second resin and a third resin are put into the first resin kneaded by the first kneading machine and kneads, and the second kneading device causes to change the ratio of the input amount of the second resin and the input amount of the third resin according to the viscosity of the kneaded product extruded from the second kneader.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Various methods are being considered for recovering resin components that are not put to practical use, such as resin components recovered from waste products (consumer materials) and resin components that do not meet the standards for sales products (off-grade materials) that are inevitably produced in the manufacturing process, and processing them so that they can be reused (hereinafter, the above-mentioned recovered resin components will be referred to simply as "recovered resins," and resin components obtained by processing recovered resins into a form suitable for reuse will be referred to simply as "recycled resins").

[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 pellets.

[0004] According to Patent Document 1, waste plastics to be reused have different melt flow rates (MFR) depending on their form and physical properties, and it is difficult to pelletize them into pellets with a specified MFR. In order to solve the above problem, Patent Document 1 adds peroxide to polymer resins such as polyolefins to reduce their molecular weight. Specifically, the pelletizer described in Patent Document 1 has a first extruder into which waste plastics are fed and kneaded, and a second extruder that is installed downstream of the first extruder and feeds peroxide into the molten plastic extruded from the first extruder. The pelletizer measures the MFR of the molten plastic extruded from the first extruder inline, and adjusts the amount of peroxide fed into the second extruder based on the measured MFR of the molten plastic, thereby pelletizing pellets with a specified MFR. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-65092 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is expected that the pelletizer described in Patent Document 1 can produce pellets with a specified MFR and viscosity from waste plastics. However, the peroxides that the pelletizer described in Patent Document 1 feeds in the second extruder may remain in the pelletized 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 recycled resin having a predetermined viscosity from recovered resin while suppressing the addition of impurities. [Means for solving the problem]

[0008] A kneading apparatus according to one aspect of the present invention for solving the above problems includes a second kneader that feeds a second resin into a first resin mixed by a first kneader and kneads the second resin. The second kneader changes the amount of the second resin fed depending on the viscosity of the first resin mixed by the first kneader.

[0009] A kneading device according to another aspect of the present invention for solving the above problems includes a second kneader that feeds a second resin and a third resin into the first resin mixed by the first kneader and kneads them together. The second kneader changes the ratio between the amount of the second resin fed and the amount of the third resin fed depending on the viscosity of the mixture extruded from the second kneader. Effect of the Invention

[0010] According to the present invention, there is provided a kneading device capable of obtaining a recycled resin having a predetermined viscosity from recovered resin while suppressing the addition of impurities. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a kneading device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a kneading device according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of a kneading device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the kneading device of the present invention will be described with reference to several embodiments.

[0013] [First embodiment] 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 recovered resin to regenerate it into a recycled resin having a predetermined viscosity.

[0014] The above-mentioned recovered resins are typically resin components recovered from waste products, or resin components that are inevitably produced in the manufacturing process and do not become part of the final product. These recovered resins contain a wide variety of resin types in different ratios, metals other than resin, or additives such as pigments and release agents. After being crushed, the above-mentioned recovered resins are subjected to magnetic separation or the like to remove metal components such as iron, and are separated into resin types by gravity separation. However, even with these processes, it is almost impossible to completely separate each component.

[0015] For example, resins recovered from discarded automobiles contain a mixture of polyethylene, polypropylene, polyamide, polyurethane, etc., in the resin components after removing metal components. If gravity separation is performed on these resin components, it is possible to separate the mixture of polyethylene and polypropylene from the polyamide. However, separating polyethylene and polypropylene by gravity separation is not realistic in terms of time and cost. The ratio of polyethylene to polypropylene varies depending on the type and parts of the automobile.

[0016] Therefore, if the recycled resin collected from the discarded automobiles is melted and kneaded as it is, the ratio of polyethylene and polypropylene in the resulting recycled resin will vary widely. The viscosity and fluidity of the resulting recycled resin will also vary depending on the ratio. Due to the unpredictability of the viscosity and fluidity, it is very difficult to reuse the resulting recycled resin as it is.

[0017] The kneading device 100 melts and kneads such recovered resin, and further mixes and melts and kneads other resins, thereby regenerating a recycled resin having a predetermined viscosity.

[0018] The kneading device 100 is a tandem-type extruder having a first kneader 110 and a second kneader 120 connected downstream of the first kneader 110. A viscometer 130 that measures the viscosity of the recovered resin kneaded by the first kneader 110 in-line is disposed at a position subsequent to the first kneader 110 and preceding the second kneader 120.

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

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

[0021] The cylinder 112 is a container for kneading the recovered resin put inside with a screw 114. The cylinder 112 may have a heating section for adjusting the internal temperature to melt the recovered resin.

[0022] One or more screws 114 are arranged inside the cylinder 112, and are rotated by a motor (not shown) to knead the recovered resin inside the cylinder 112. A twin-screw extruder consisting of two screws can adjust the kneading characteristics by combining screw segments with various types of kneading characteristics such as forward flight, kneading, and reverse flight, and can be appropriately selected depending on the type and physical properties of the resin. Furthermore, an extruder consisting of multiple screw shafts can also be appropriately selected depending on the kneading performance.

[0023] The hopper 116 is an inlet for feeding recovered resin into the inside of the cylinder 112. In this embodiment, the hopper 116 feeds recovered resin containing polyethylene and polypropylene, which has been collected from discarded automobiles and separated by magnetic separation and specific gravity separation after crushing, into the inside of the cylinder 112.

[0024] The extruding unit 118 communicates with one end of the resin flow path 140, and extrudes the recovered resin that has been fed into the cylinder 112 and melted and kneaded by the rotation of the screw 114, into the resin flow path 140 that communicates with the second kneader 120. The extruding 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 resulting recycled resin within a predetermined range by adding another resin (hereinafter simply referred to as "additive resin") to the recovered resin kneaded in the first kneader 110 and further melt-kneading the resin.

[0026] Specifically, the second kneader 120 has a long cylindrical cylinder 122, a screw 124 rotatably arranged in the inner bore of the cylinder 122, an inlet 126 for introducing the recovered resin melted and kneaded by the first kneader 110 into the cylinder 122, a hopper 127a for introducing added resin into the cylinder 122, a hopper 127b for introducing additives such as rubber and talc into the cylinder 122, and an extrusion section 128 for extruding the kneaded recovered resin.

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

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

[0029] The inlet 126 is connected to the other end of the resin flow path 140, and introduces the recovered resin that has been melted and kneaded in the first kneader 110 and extruded from the extrusion section 118 from the resin flow path 140 into the inside of the cylinder 122 of the second kneader 120.

[0030] The hopper 127a is an inlet for feeding the added resin into the cylinder 122. The added resin is a resin with a known viscosity, and is added to and mixed with the recovered resin to adjust the viscosity of the recovered resin to a predetermined range. The added resin may be the same type of resin as the recovered resin (polyethylene or polypropylene in this embodiment), or may be a different type of resin from the recovered resin.

[0031] The hopper 127a changes the amount of added resin fed in accordance with the viscosity of the recovered resin measured by the viscometer 130. The control for changing the amount of added resin fed from the hopper 127a will be described later.

[0032] The hopper 127b is an inlet for feeding additives such as stabilizers, antioxidants, and crystal nucleating agents, and fillers such as rubber, talc, and calcium carbonate into the cylinder 122. In addition, reinforcing fiber materials such as glass fiber, carbon fiber, and organic fiber can also be added. The addition of these fillers and reinforcing fibers has a significant effect on the viscosity, but the viscosity of the resin at the time of addition is uniformly controlled, and even if a certain amount of filler or reinforcing fiber is added, there is no change in the viscosity due to the addition. This is within the range that can be predicted by theoretical formulas or empirical formulas, so the addition of these additives does not make the viscosity of the resulting recycled resin unpredictable.

[0033] The extrusion section 128 has a die and the like, 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 that measures the viscosity of the recovered resin melted and kneaded in the first kneader. The viscometer 130 may be a known viscometer that measures the viscosity of a part of the recovered resin that is melted and kneaded in the first kneader 110 and moves to the second kneader. For example, devices for measuring viscosity in-line are introduced in R. Gendron, LE Daigneault, J. Cell. Plast., 35, 221 (1999) and M. Lee, CB 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 addition, in the formula (1), φ1 represents the volume fraction of the first resin (in this embodiment, the recovered resin) with respect to the total volume of the resin components charged into the second kneader, η1 represents the viscosity of the first resin, φ2 represents the volume fraction of the second resin (in this embodiment, the added resin) with respect to the total volume of the resin components charged into the second kneader, η2 represents the viscosity of the second resin, and η Blend represents the viscosity of the resulting mixture.

[0041] Here, the viscosity η1 of the first resin is the viscosity of the recovered resin kneaded by the first kneader, measured by the viscometer 130. Also, the viscosity η2 of the second resin (the viscosity of the added resin) is known. In formula (1), the unknown values ​​are φ1 and φ2. However, since φ1 and φ2 are φ1+φ2=1 in this embodiment, φ2 can be read as 1-φ1. In other words, the only unknown value in formula (2) is φ2.

[0042] Therefore, these values ​​and the viscosity η of the recycled resin to be obtained Blend By substituting the values ​​of and into formula (1), the volume fraction φ2 of the added resin to be fed into the second kneader 120 can be calculated. The actual volume V1 of the first resin can be calculated from the rotation speed of the gear pump of the extrusion section 218 attached to the first kneader 110. Therefore, the volume V2 of the second resin (added resin) to be fed from the hopper 127a to the second kneader 120 can be calculated by V1 × (φ2 / φ1). Since the viscosity of the resin is shear rate dependent, a viscosity corresponding to the shear rate condition of the in-line viscosity measurement is selected. As another method, a model expressing the shear rate dependency of the resin viscosity (Cross formula, Bird-Carreau formula, Carreau-Yasuda formula, etc.) can be introduced into formula (1) and expanded to improve the accuracy of viscosity control.

[0043] For example, if the viscosity of the second resin (additive resin) is 5.5×10 4It is assumed that the viscosity η1 of the first resin (recovered resin kneaded in the first kneader) measured by the viscometer 130 is each of the values ​​shown in Table 1. In this case, the viscosity η Blend is 3.0×10 4 If one wishes to obtain recycled resin with a Pa·s, the amount of added resin put into the inside of the cylinder 122 of the hopper 127a should be determined so that the volume fraction φ1 of the first resin (recovered resin) and the volume fraction φ2 of the second resin (added resin) are in the following ratio:

[0044] [Table 1]

[0045] Thus, according to the first embodiment described above, the viscosity of the obtained recycled resin can be adjusted to a predetermined range simply by changing the amount of the added resin to be added to the second kneader. Therefore, the addition of impurities is not necessary, and the physical properties of the obtained recycled resin are unlikely to change unexpectedly. In addition, the method of adjusting the MFR of the recycled resin by adjusting the amount of additives other than the resin, as described in Patent Document 1, may not be usable depending on the type of recovered resin. For example, polypropylene has a lower molecular weight and an increased MFR due to molecular chain scission by peroxide, while polyethylene is crosslinked by peroxide, which increases the molecular weight and decreases the MFR. In contrast, the present invention makes it possible to uniform the viscosity of the recycled resin even in a mixture of waste plastics in which polypropylene and polyethylene may be mixed.

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

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

[0048] The first kneader 210 has a long cylindrical cylinder 212, a screw 214 rotatably arranged in the inner hole of the cylinder 212, a hopper 216 for feeding recovered resin into the cylinder 212, and an extrusion unit 218 for extruding the kneaded recovered resin. The configurations and functions of these are similar to those of the cylinder 112, the screw 114, the hopper 116, and the extrusion unit 118 of the first kneader 110 in the first embodiment, respectively, and therefore a duplicated description will be omitted. In this embodiment, the hopper 216 also feeds into the cylinder 212 recovered resin containing polyethylene and polypropylene that has been collected from discarded automobiles and separated by magnetic separation and specific gravity separation after crushing.

[0049] The second kneader 220 has a long cylindrical cylinder 222, a screw 224 rotatably arranged in the inner hole of the cylinder 222, an inlet 226 for introducing the recovered resin melted and kneaded by the first kneader 210 into the cylinder 222, a hopper 227a for introducing additive resin into the cylinder 222, a hopper 227b for introducing additives such as rubber and talc into the cylinder 222, and an extrusion unit 228 for extruding the kneaded recovered resin. The configurations and functions of the cylinder 212, the screw 214, the hopper 227b, and the extrusion unit 218 are similar to those of the cylinder 212, the screw 214, the hopper 227b, and the extrusion unit 218 of the second kneader 120 in the first embodiment, respectively, and therefore will not be described again.

[0050] The viscometer 230 is an in-line viscometer that measures the viscosity of the recovered resin melted and kneaded in 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 that allows the recovered resin melted and kneaded in the first kneader 210 to flow through. The configurations and functions of the viscometer 230 and the resin flow path 240 are similar to those of the viscometer 130 and the resin flow path 140 in the first embodiment, respectively, and therefore will not be described again.

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

[0052] In the kneading device 200 of this embodiment, the hopper 227a changes the amount of the first added resin and the second added resin added depending on the viscosity of the recovered resin melted and kneaded in the first kneader 210, measured by the viscometer 230.

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

[0054]

number

[0055] In addition, in the formula (2), φ1 represents the volume fraction of the first resin (in this embodiment, the recovered resin) with respect to the total amount (total volume of the resin components charged into the second kneader) of the volume of the recovered resin introduced into the second kneader 220, the volume of the first added resin charged into the second kneader 220, and the volume of the second added resin charged into the second kneader 220, η1 represents the viscosity of the first resin, φ2 represents the volume fraction of the second resin (in this embodiment, the first added resin) with respect to the total volume of the resin components charged into the second kneader, η2 represents the viscosity of the second resin, φ3 represents the volume fraction of the third resin (in this embodiment, the second added resin) with respect to the total volume of the resin components charged into the second kneader, η3 represents the viscosity of the third resin, and η Blend represents the viscosity of the resulting mixture.

[0056] In this embodiment, the viscosity η1 of the first resin is the viscosity of the recovered resin kneaded by the first kneader, measured by the viscometer 230. The viscosity η2 of the second resin (first added resin) and the viscosity η3 of the third resin (second added resin) are known.

[0057] In this embodiment, the volume fraction φ1 of the first resin can be calculated from the amount of recovered resin fed from the hopper 216 to the first kneader 210 and the amount of recycled resin to be obtained.

[0058] In formula (2), the unknown values ​​are φ2 and φ3, but in this embodiment, φ1, φ2, and φ3 are φ1+φ2+φ3=1, so φ3 can be read as 1-φ1-φ2. In other words, the only unknown value in formula (2) is φ2.

[0059] Therefore, these values ​​and the viscosity η of the recycled resin to be obtained Blend By substituting the values ​​of and into equation (2), the volume fraction φ2 of the first additive resin (second resin) to be added to the second kneader 220 can be calculated, and from the calculated value of φ2, the volume fraction φ3 of the first additive resin (third resin) to be added to the second kneader 220 can be calculated.

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

[0061] As described above, in this embodiment, recycled resin containing polyethylene and polypropylene is melt-kneaded. Compared with a mixture of resins of the same type, such a mixture of different types of resins is more likely to have a decrease in strength due to phase separation between the different resins. Therefore, it is preferable that the ratio of the recycled resin in the recycled resin obtained by melt-kneading is at most about 30%. In addition, a compatibilizer such as a copolymer of polyethylene and polypropylene can be added to the first kneader together with the recycled resin to make phase separation less likely to occur. Furthermore, at this time, the two types of added resins (the second resin and the third resin) can be made to be the same type of resin (for example, both are polyethylene or both are polypropylene), thereby making it possible to make it less likely that a decrease in strength due to phase separation between the different resins will occur.

[0062] In this case, if the volume fraction of the recovered resin (first resin) is a predetermined value (e.g., 30%), the total amount of the volume fraction of the first added resin (second resin) and the volume fraction of the second added resin (third resin) added in the second kneader is also determined (e.g., 70%). If the amount (volume) of recovered resin introduced into the second kneader 220 is kept constant, the total amount of the amount (volume) of the first added resin and the amount (volume) of the second added resin put into the second kneader 220 will also be constant (volume of recovered resin x (70 / 30)). In this embodiment, the total amount (volume) of the recovered resin introduced into the second kneader 220, the amount (volume) of the first additive resin fed into the second kneader 220, and the amount (volume) of the second additive resin fed into the second kneader 220 can be kept within a predetermined range, and the amount (volume) of the resulting recycled resin can also be kept within a predetermined range.

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

[0064] In this way, according to this embodiment, by setting the ratio of recovered resin contained in the obtained recycled resin and the viscosity of the recycled resin, it is possible to keep the amount (volume) of the obtained recycled resin within a predetermined range while also keeping the viscosity of the recycled resin within a predetermined range.

[0065] Specifically, the viscosity η2 of the second resin (first additive resin) is 2.0×10 5 Pa s, and the viscosity η3 of the third resin (second additive resin) is 6.0×10 3 Suppose that the viscosity η1 of the recovered resin kneaded by the first kneader measured by the viscometer 230 is each of the values ​​shown in Table 1. In this case, the content of the recovered resin (corresponding to φ1) is 30%, and the viscosity η Blend is 3.0×10 4 If one wishes to obtain recycled resin with a Pa·s, the amount of the second resin (first added resin) and the third resin (second added resin) put into the inside of the cylinder 222 of the hopper 227a should be changed so that the volume fraction φ2 of the second resin (first added resin) and the volume fraction φ3 of the third resin (second added resin) are in the following ratio:

[0066] [Table 2]

[0067] As is clear from Table 2, according to this embodiment, when attempting to obtain recycled resin with a content of recovered resin within a predetermined range, it is possible to obtain recycled resin having a predetermined viscosity simply by adjusting the ratio between the volume of the first added resin and the volume of the first added resin that hopper 227a puts into the interior of cylinder 122.

[0068] In this way, according to the second embodiment described above, the viscosity of the resulting recycled resin can be adjusted to a predetermined range simply by changing the ratio between the volume of the first additive resin and the volume of the second additive resin fed into the second kneader. Therefore, the addition of impurities is not necessary, and unexpected changes in the physical properties of the resulting recycled resin are unlikely to occur. In addition, by setting the amount of recovered resin fed into the first kneader and the content of recovered resin in the resulting recycled resin, both the viscosity and volume of the resulting recycled resin can be adjusted to a predetermined range simply by changing the ratio between the volume of the first additive resin fed into the second kneader and the volume of the second additive resin fed into the second kneader.

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

[0070] The kneading apparatus differs from the kneading apparatus 100 according to the first embodiment in that it has a spectrometer 350 that measures the infrared spectrum of the recovered resin melted and kneaded by the first kneader 110. The other configurations are the same as those of the first embodiment, so that a duplicated description will be omitted.

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

[0072] Hindered phenol antioxidants are commonly used as heat stabilizers for polyethylene and polypropylene resins. For example, the hindered phenol antioxidant Irganox 1010 has a CO stretching band in the IR spectrum of 1300-1000 cm -1 The stretching of C=O is seen at 1750-1735cm -1 When the antioxidant ignited during the production of the recovered resin is consumed due to thermal degradation during use, these characteristic peaks in the IR spectrum measured in-line become smaller or disappear. Therefore, the amount of heat stabilizer in the obtained recycled resin can be adjusted to a constant value by changing the amount of heat stabilizer added from the hopper 127b of the second kneader according to the height of the IR spectrum peak caused by the heat stabilizer measured by the spectrometer 350. The amount of heat stabilizer to be added can be determined based on a calibration curve that is created in advance between the height of the IR spectrum peak and the amount added. Alternatively, the amount of heat stabilizer to be added can be changed based on an empirical formula.

[0073] The additives whose amounts are changed are not limited to heat stabilizers, and any type of additives can be used.

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

[0075] [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 the above-described embodiments. Needless to say, various other embodiments are possible within the scope of the concept of the present invention.

[0076] For example, in each of the above-mentioned embodiments, the viscosity of the melt-kneaded recovered resin is measured by a viscometer installed downstream of the first kneader, but the viscometer may be disposed inside the first kneader, or may be disposed in a resin flow path connecting the first kneader and the second kneader. Also, the viscometer may be configured to measure the pressure and flow rate of the recovered resin extruded from an extrusion section of the first kneader, and calculate the viscosity of the recovered resin from these values.

[0077] In addition, in each of the above-mentioned embodiments, the additive resin, which is polyethylene or polypropylene, is added to the recycled resin containing polyethylene and polypropylene, but the resin type is not limited to these in the off-grade material or the separated and sorted recycled material, such as polyethylene alone, polypropylene alone, polyester alone, etc. 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, polyester, etc.

[0078] In the second embodiment, two types of additive resins are added in the second kneader to the recovered resin melted and kneaded in the first kneader, but three or more types of additive resins may be added in the second kneader. Also, 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 may be added in the second kneader.

[0079] In addition, in each of the above-mentioned embodiments, recovered resin is added to the first kneader, but not only recovered resin, but also virgin material may be added to the first kneader, or natural resin with unknown viscosity may be added to the first kneader. Also, liquid ethylene-propylene rubber, pellet-shaped ethylene-propylene rubber, ethylene-butene rubber, propylene-butene rubber, or propylene-butene-ethylene rubber may be added to the first kneader as a compatibilizer for polyethylene-polypropylene copolymers.

[0080] In each of the above-mentioned embodiments, the extrusion section of the second kneader may extrude the recycled resin into any known shape including a sheet, a film, a rod, a plate, a pipe, a modified cross-section molded product, a strand, etc. Also, a cutter or the like may be disposed downstream of the extrusion section to process the extruded recycled resin into pellets. Alternatively, a known molding machine may be disposed downstream of the extrusion section 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 added resin added from hopper 127a or hopper 227a, the amount of the additive added from hopper 127b or hopper 227b was changed. However, it is also possible to only change the amount of the additive in accordance with the infrared spectrum measured by the spectroscopic device without changing the amount or ratio of the added resin.

[0082] In each of the above-mentioned embodiments, the kneading device may have each of the above-mentioned operations controlled by a control unit (not shown). That is, the control unit controls the operation of a hopper of the first kneader to feed the recovered resin from the hopper into the cylinder of the first molding machine. Furthermore, the control unit controls the operation of the cylinder and screw (or motor) of the first kneader to heat and melt the recovered resin fed into the cylinder, and knead it. Furthermore, the control unit controls the operation of an extrusion unit of the first kneader to extrude the melted and kneaded recovered resin from the first kneader and introduce it into the cylinder of the second kneader from the inlet of the second kneader. Furthermore, the control unit controls the operation of a hopper of the second kneader to add one or more types of additive resins and optional additives into the cylinder of the second kneader. Furthermore, the control unit controls the operation of the cylinder and screw (or motor) of the second kneader to heat, melt, and knead the recovered resin and added resin (and additives) fed into the cylinder. Furthermore, the control unit controls the operation of the extrusion unit of the second kneader to extrude the melt-kneaded resin components from the second kneader. At this time, the control unit changes the amount of added resin added from the hopper of the second kneader (or the ratio between the amount of the second added resin and the amount of the third added resin) according to the viscosity of the recovered resin melt-kneaded in the first kneader. [Industrial Applicability]

[0083] According to the kneading device of the present invention, recycled resin having a predetermined viscosity can be obtained from recovered resin. In this case, 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 make it more difficult for unnecessary impurities to remain in the obtained recycled resin. The kneading device of the present invention can homogenize the viscosity of recycled resin obtained from consumer materials and off-grade materials and regenerate them into recycled resin that can be easily used for various applications, so it is expected to expand the scope of reuse of these resins and contribute to improving the efficiency of resin recycling. [Explanation of symbols]

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

Claims

1. a second kneader that adds a second resin to the first resin kneaded by the first kneader and kneads them together; and a control unit that determines a volume fraction of the second resin with respect to a total volume of the resin components input into the second kneader based on a viscosity of the first resin kneaded by the first kneader, The second kneader introduces the second resin in an amount corresponding to the volume fraction of the second resin calculated by the control unit. Kneading equipment.

2. The first kneader has a viscometer for measuring the viscosity of the first resin kneaded by the first kneader, the control unit calculates a volume fraction of the second resin with respect to a total volume of the resin components input into the second kneader, based on the viscosity of the first resin measured by the viscometer; 2. The kneading device according to claim 1.

3. The kneading device according to claim 1 or 2, wherein the control unit calculates a volume fraction of the second resin relative to a total volume of the resin components fed to the second kneader based on the viscosity of the second resin and the viscosity of the first resin kneaded by the first kneader.

4. 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.

5. 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.

5. The kneading device according to claim 4.

6. The first resin is a mixture containing polyethylene and polypropylene. The kneading device according to any one of claims 1 to 5.

7. The kneading device according to any one of claims 1 to 6, further comprising a first kneader for kneading the first resin, and the second kneader is connected downstream of the first kneader.

8. 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 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.

9. The second kneader is configured to input, as the second resin, a resin having a higher viscosity than a 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 8.

10. 10. The kneading apparatus according to claim 8, further comprising a first kneader for kneading the first resin, and the second kneader is connected downstream of the first kneader.

11. 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 spectrometer. The kneading device according to any one of claims 1 to 10.

12. 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.

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