JP2008279728A - Recycling method for plastic waste material, regenerated plastic material, and regenerated plastic molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for separating plastic wastes into each system of plastic at a low cost in such a manner that fouling of a specific gravity sorting liquid which is used for the specific gravity sorting is made little, and the specific gravity sorting liquid is made to be able to be circulated by using an inexpensive apparatus. <P>SOLUTION: This recycling method for plastic waste material includes the washing process, the washing liquid separating process, the specific gravity sorting process, and the specific gravity sorting liquid separating process. In this case, the plastic waste material including a plurality of kinds of plastics having different specific gravities is washed with a washing liquid in the washing process. In the washing liquid separating process, the plastic waste material and the washing liquid are separated. In the specific gravity sorting process, the plastic waste material is sorted with the specific gravity sorting liquid conforming to the specific gravity difference in the plastics. In the specific sorting liquid separating process, the sorted plastic waste material and the specific gravity sorting liquid are separated. Then, the specific gravity sorting liquid which has been separated in the specific gravity sorting liquid separating process is circulated to the specific gravity sorting process for the recycling method for a plastic waste material. Also, a regenerated plastic material and a regenerated plastic molded article which have been obtained by the method are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for recycling plastic waste, a recycled plastic material, and a recycled plastic molded body.

  In recent years, with the reduction of landfill sites and effective use of resources, the Home Appliance Recycling Law was introduced in April 2001, especially for home appliances that are difficult to crush at ordinary large waste disposal facilities and contain many useful resources. Was enforced. According to this Home Appliance Recycling Law, as of December 2006, it is obliged to recycle four items of home appliances: air conditioners (air conditioners), television receivers (TVs), refrigerators, and washing machines. Regarding the recycling rate, legal standard values of 60% or more for air conditioners, 55% or more for televisions, 50% or more for refrigerators, and 50% or more for washing machines are set.

  However, plastic products such as home appliances generally include a plurality of plastic members, and the plastic members are often made of different plastic materials, and are plastic composite members made of different plastic materials. There are many cases.

  Here, the plastic parts contained in these plastic product wastes (plastic waste materials) are processed again and used as components for various plastic products such as home appliances, or as raw materials for them. It is necessary to process the plastic again after separating the plastic from the member for each system. Conventionally, many development efforts have been made in various fields regarding a method of separating and recycling a plastic member for each system of plastic composition from plastic waste.

  For example, Japanese Patent Application Laid-Open No. 7-136546 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2000-288422 (Patent Document 2) use a difference in specific gravity of a mixed plastic to separate the plastics in each liquid system in a liquid. A separation and recovery method and apparatus are disclosed. In the method and apparatus for separating and collecting plastics disclosed in Patent Documents 1 and 2, when a mixed plastic member or a crushed material of a mixed plastic member is put into a liquid (specific gravity sorting liquid), a mixed plastic smaller than the liquid specific gravity floats. However, the mixed plastic larger than the liquid specific gravity is separated by utilizing the settling. However, in this case, the specific gravity sorting liquid immediately becomes dirty due to dirt (mold, crushed pieces, etc.) adhering to the plastic waste, and when the plastic is recontaminated with the dirty specific gravity sorting liquid, the screen of the extruder is clogged. In other words, dirt is mixed in the recycled plastic, and oxidation of the plastic progresses from that portion, resulting in a problem that long-term reliability is lowered.

  Therefore, the specific gravity sorting liquid is frequently replaced, or, as disclosed in JP 2002-136777 A (Patent Document 3), a flocculant is added to the specific gravity sorting liquid used in the specific gravity sorting step, and the aggregate There has also been proposed a method in which the specific gravity sorting solution is circulated after use.

However, if the specific gravity sorting liquid is frequently changed, the cost for treating wastewater increases. Further, in the method of adding a flocculant to the specific gravity sorting liquid used in the specific gravity sorting process as disclosed in Patent Document 3, and removing the aggregate and circulating the specific gravity sorting liquid, the cost of the flocculant and the cost of the apparatus are reduced. Is large, and the cost of separating the plastic becomes high.
JP-A-7-136546 JP 2000-288422 A JP 2002-136777 A

  The present invention has been made to solve the above-described problems, and the object of the present invention is to reduce the contamination of the specific gravity selection liquid used for specific gravity selection and to allow the specific gravity selection liquid to be circulated using an inexpensive apparatus. Therefore, it is providing the method of isolate | separating for every system | strain of plastic at low cost.

  The method for recycling plastic waste material according to the present invention includes a cleaning process for cleaning plastic waste material containing a plurality of types of plastics having different specific gravities with a cleaning liquid, a cleaning liquid separation process for separating the plastic waste material and the cleaning liquid, The specific gravity sorting liquid separated by the specific gravity sorting liquid separation process includes a specific gravity sorting process for sorting with the specific gravity sorting liquid based on the specific gravity difference, and a specific gravity sorting liquid separation process for separating the sorted plastic waste material and the specific gravity sorting liquid. It circulates in the specific gravity sorting process.

  In the plastic waste material recycling method of the present invention, it is preferable to circulate the cleaning liquid separated in the cleaning liquid separation process to the cleaning process.

  In the method for recycling plastic waste material according to the present invention, it is preferable that the specific gravity sorting liquid and the cleaning liquid have the same composition.

  Moreover, in the plastic waste material recycling method of the present invention, it is preferable to supply the specific gravity sorting liquid used in the specific gravity sorting step to the cleaning step.

  In the plastic waste material recycling method of the present invention, it is preferable to supply a new specific gravity sorting liquid to the specific gravity sorting step.

  In the method for recycling plastic waste material according to the present invention, it is also preferable to rinse the plastic waste material with the specific gravity sorting liquid used in the specific gravity sorting process after the washing liquid separation step.

  The plastic waste material recycling method of the present invention preferably further includes a foreign matter removing step of removing foreign matter, and the foreign matter removing step is a step of removing foreign matter using a strainer and / or a centrifuge. Is more preferable.

  The specific gravity separation liquid used in the method for recycling plastic waste material according to the present invention preferably has a specific gravity of 0.92 to 1.00.

  The plastic waste material recycling method of the present invention preferably includes an air separation step before the cleaning step.

  The plastic waste material in the present invention is preferably separated and collected from at least one waste selected from televisions including flat-screen televisions, microwave ovens, dryers, air conditioners, refrigerators, and washing machines.

  The present invention also provides a recycled plastic raw material obtained by the above-described method for recycling plastic waste materials according to the present invention. The recycled plastic raw material of the present invention is preferably in the form of pellets.

  The present invention is further a plastic molded body obtained by molding the above-mentioned recycled plastic raw material of the present invention, and at least any selected from a television including a flat-screen television, a microwave oven, a dryer, an air conditioner, a refrigerator, and a washing machine. The present invention also provides a recycled plastic molded body used for such plastic members.

  According to the plastic waste material recycling method of the present invention, a plurality of types of plastic waste materials can be separated and recovered at low cost.

  The present invention relates to a method for producing (recycling) plastic raw material regenerated from plastic contained in plastic product waste (plastic waste), and the plastic waste containing a plurality of types of plastics having different specific gravities is used as a cleaning liquid. A cleaning process for cleaning, a cleaning liquid separating process for separating plastic waste and cleaning liquid, a specific gravity sorting process for sorting plastic waste with specific gravity sorting liquid based on the specific gravity difference of the plastic, and the sorted plastic waste material and specific gravity sorting liquid It includes a specific gravity sorting liquid separating step for separating and a specific gravity sorting liquid circulating step for circulating the separated specific gravity sorting liquid to the specific gravity sorting step.

  Here, examples of the plastic system that is material-recycled by the plastic waste recycling method of the present invention include, for example, polyolefin, polystyrene, polycarbonate, polymethacrylate, and the like. Of these, polyolefin plastics such as polyethylene and polypropylene, and polystyrene plastics such as polystyrene and ABS are superior in terms of processability and economy compared to other plastics. In the method for recycling plastic waste material according to the invention, it is possible to suitably perform material recycling.

  FIG. 1 is a flowchart schematically showing a preferred example of the plastic waste material recycling method of the present invention. Hereinafter, taking the case shown in FIG. 1 as an example, the plastic waste material recycling method of the present invention will be described in detail.

[1] Plastic Waste Material Recovery Step In the example shown in FIG. 1, first, used plastic waste material discarded from a home or the like is recovered (step 101). “Plastic waste material” means waste of a product (plastic product) including a plastic member as described above, and is not particularly limited as long as it is such as, for example, a refrigerator, a washing machine, Home appliances such as an air conditioner, a television (including a flat-screen television), and OA equipment can be given. Among these, it is preferable to collect a refrigerator, a washing machine, an air conditioner, a television (including a flat-screen television), and a microwave oven. In the case described below with reference to FIG. 1, the case where the refrigerator and the washing machine are collected will be described as an example. In addition, the plastic waste material collect | recovered may be one type, and may collect two or more types of plastic waste materials and use them for the procedure of one recycling method.

[2] Dismantling Step Next, in the example shown in FIG. 1, the recovered plastic waste material, which is waste from the refrigerator, washing machine, air conditioner, TV (including flat-screen TV), and microwave oven, is dismantled, compressor, heat exchange A large metal part such as a container or a substrate is excluded (step 102). This dismantling process is generally performed by manual dismantling by an operator.

[3] Member Recovery Step Next, in the example shown in FIG. 1, from the disassembled refrigerator, washing machine, air conditioner, TV (including flat-screen TV), microwave oven waste, washing machine water tank, refrigerator vegetable case A specific plastic member such as is selectively collected (step 103). The plastic waste material recycling method of the present invention preferably includes such a member recovery step. Here, it is preferable that the selective recovery of the specific plastic member is performed based on the information on the plastic component constituting the plastic member included in the plastic waste material and the information on the ease of taking out the plastic member. Further, the plastic member recovered in the process may include a metal or a plurality of types of plastics.

[4] First crushing step In the example shown in FIG. 1, next, the plastic member recovered in the member recovery step (step 103) described above is crushed to obtain a first crushed material (X) (step 104). ). The plastic waste material recycling method of the present invention preferably includes the first crushing step for crushing the plastic waste material (in this case, the plastic member). As the crushing method, a conventionally known method can be used, and examples thereof include a method using a hammer crusher and a biaxial crusher. Among them, it is preferable to use a hammer type crusher because even if iron bolts or the like are mixed, the crusher blade can be stably broken without being damaged. A conventionally well-known hammer type crusher can be used, and a suitable example is Aldair (manufactured by Kubota Corporation). A conventionally well-known thing can also be used for a biaxial crusher, As a suitable specific example, dual mastiff (made by Kubota Corporation) is mentioned.

  The particle size of the first crushed material (X) obtained in this step is preferably 20 mm or more, and more preferably 30 mm or more. Moreover, it is preferable that the particle size of 1st crushed material (X) is 200 mm or less, and it is more preferable that it is 150 mm or less. When the particle size of the first crushed material (X) is less than 20 mm or more than 200 mm, the metal selection accuracy (to be described later) suitably performed in the present invention tends to decrease the metal selection accuracy, and When the particle size of the first crushed material (X) is less than 20 mm, it takes a long time for crushing, and the plastic tends to melt or undergo thermal oxidative degradation. Furthermore, when the particle size of the first crushed material (X) exceeds 200 mm, the bulk specific gravity decreases, and the workability in the subsequent steps tends to be adversely affected.

[5] Metal Removal Step In the example shown in FIG. 1, next, the foreign matter (B) made of metal is removed from the first crushed material (X) (step 105). Thus, in the plastic waste material recycling method of the present invention, when selecting a specific plastic waste material (in this case, plastic crushed material) to be recycled from the first crushed material (X). It is preferable that the method further includes a metal removal step of removing the foreign matter (B) made of metal. By including the metal removal step, the metal foreign matter that has not been removed in the first crushing step (step 104) described above can be efficiently removed, resulting in cost reduction.

  Here, among the foreign matter (B) made of metal, it is preferable to remove the iron-based foreign matter using, for example, a magnetic force, but is not limited thereto. Of the foreign matter (B) made of metal, aluminum-based foreign matters and copper-based foreign matters are preferably removed using, for example, eddy current, but are not limited thereto. In addition, when performing both metal removal using magnetic force and metal removal using eddy current, the order is not particularly limited, but from the viewpoint of efficiency, iron-based foreign matters are first removed by magnetic force, and then eddy current is removed. It is preferable to remove aluminum-based and copper-based foreign matters with an electric current.

  In the metal removal process, the plastic waste after the above metal removal (in this case, plastic crushed material) is detected by a metal detector and a magnetic detector, and the residual metal is detected using a conveyor switching device. Is preferably removed. Here, by removing the residual metal, it is possible to prevent the blade of the crusher used in the second crushing step suitably performed in the subsequent steps from being damaged. In the first crushing step (step 104), when a metal foreign matter such as a screw is removed, a magnetic detector, a magnetic detector is not used without using a magnetic separator or an eddy current type metal removing device. It is also possible to remove the remaining metal using only

  Further, in the case of a plastic member composed almost exclusively of plastic, the first crushing step (step 104) and the metal removal step (step 105) described above are omitted by manually dismantling and collecting the plastic member. Also good.

[6] Second crushing step In the example shown in FIG. 1, next, the first crushed material (X) from which the foreign substance (B) made of metal has been removed is further finely crushed, and the second crushed material (Y ) Is obtained (step 106). Thus, it is preferable that the plastic waste material recycling method of the present invention further includes a second crushing step after the first crushing step (step 104). By including the second crushing step, there is an advantage that the workability of the molded body manufacturing step (step 112) performed later and the sorting accuracy in the specific gravity sorting step (step 110) are improved.

  The crushing method used in the second crushing step is not particularly limited, but can be performed using, for example, a uniaxial crusher, a biaxial crusher, a shredder, or the like.

  The particle size of the second crushed material (Y) obtained in the second crushing step is preferably 5 mm or more, and more preferably 8 mm or more. Moreover, it is preferable that the particle size of a 2nd crushed material (Y) is 30 mm or less, and it is more preferable that it is 20 mm or less. When the particle size of the second crushed material (Y) is less than 5 mm, it takes a long time for crushing, so the plastic tends to melt or undergo thermal oxidative degradation, and the second crushed material (Y) If the particle size of the steel exceeds 30 mm, the workability in the molded body manufacturing process (step 112) performed later tends to be adversely affected. Further, when the particle size of the second crushed material (Y) is less than 5 mm or more than 30 mm, it tends to adversely affect the sorting accuracy in the specific gravity sorting step (step 110) performed later.

  In the method for recycling plastic waste materials according to the present invention, the steps up to here (steps 101 to 106) may not be as described above, and the plastic mixture is recovered and crushed using another method. You may make it use for the following process.

[7] Wind separation process (step 107)
Next, in the example shown in FIG. 1, the second crushed material (Y) obtained in the second crushing step (step 106) is separated by wind force (step 107). This utilizes the difference in weight of the second crushed material (Y). Thus, in the plastic waste material recycling method of the present invention, when the specific plastic waste material (in this case, plastic crushed material) to be recycled is selected from the first crushed material (X). It is preferable to include the said wind force classification process. In the wind sorting process, it is separated from the crushed plastic material to be recycled, from the fine powder produced in the first crushing process and the second crushing process described above, dirt removed from the plastic surface, and plastic members. Lightweight crushed materials such as foamed materials and seals can be removed.

  Note that in the case of a plastic member made up almost entirely of plastic, it is possible to omit the wind power selection step (step 107) by manual disassembly and collection.

[8] Cleaning process (step 108)
In the example shown in FIG. 1, next, a plastic waste material including a plurality of types of plastics having different specific gravities (in this case, crushed material having a weight that has not been removed in the wind separation process) is washed with a washing liquid (step 108). By such a cleaning process, it is possible to remove dirt from the plastic waste material to be recycled.

  The specific cleaning method is not particularly limited. However, the cleaning liquid is stored in a container that can store the cleaning liquid, and the plastic waste material containing plural kinds of plastics having different specific gravities (weight crushed material) ) Is preferred. Furthermore, it is more preferable that the settled plastic waste (weight crushed material) is vibrated in the cleaning liquid. As a method of vibrating, for example, a method using an electromagnetic vibration feeder can be cited. Here, the plastic waste material (weight crushed material) settled and the vibration of the settled plastic waste material (weight crushed material) in the cleaning liquid may be automatic or manual.

  The cleaning liquid used in the step is not particularly limited, but for example, it is preferable to use a cleaning liquid having a specific gravity of 0.92 to 1.00 (near 1.0). Water is preferably used as the cleaning liquid having such a specific gravity, whereby it is possible to obtain the cleaning liquid at a low cost, and the waste water treatment can be easily performed at a low cost. Moreover, you may use the liquid mixture of water and surfactant as a washing | cleaning liquid. When the specific gravity of the specific gravity separation liquid is 1.01 to 1.1, a solution in which sodium chloride is dissolved in water can be suitably used. Moreover, you may make it use the solution which melt | dissolved other inorganic substances (calcium chloride etc.) as a specific gravity selection liquid in this case. It is preferable to use the same washing liquid and specific gravity separation liquid.

  In the plastic waste material recycling method of the present invention, it is preferable to supply the specific gravity sorting liquid used in the specific gravity sorting process (step 110) described later to the cleaning process. Thereby, there is an advantage that low cost can be realized in consideration of the environment. In the plastic waste recycling method of the present invention, it is preferable that the cleaning liquid used in the cleaning process and the specific gravity selection liquid used in the specific gravity selection process described later have the same composition, and water is preferably used for both. In this case, it is preferable to filter and supply the amount of water overflowing suitably used as the specific gravity selection liquid in the specific gravity separation process as the cleaning liquid in the cleaning process.

[9] Cleaning liquid separation step Next, the plastic waste after cleaning (in this case, a crushed material of weight) and the cleaning liquid are separated (step 109). The washed plastic waste material is solid-liquid separated by a vibrating sieve or the like, and the washing liquid can be separated.

  The cleaning liquid that has been separated into solid and liquid in this process can be basically used after being circulated in the cleaning process. However, since the cleaning liquid becomes dirty immediately, it is desirable to discard it at a rate of 5 to 20% of the processing amount. In particular, when heavy metal is mixed in plastic waste (weight crushed material), it is desirable to discard 10% or more in order to prevent heavy metal from remaining in the recovered material.

[10] Specific gravity sorting process Next, the plastic waste material (in this case, crushed material of weight) that has passed through the washing process (step 108) and the washing liquid separation process (step 109) is put into the specific gravity sorting liquid, and the specific gravity difference of the plastic Based on the above, sorting is performed for each system of constituent plastic components (step 110). By sorting plastic waste (weight crushed material) for each component plastic component system through this specific gravity sorting process, recycled plastic raw materials (described later) and recycling are made for each plastic waste composed of plastic components of the same system. A plastic molded body (described later) can be produced, and the purity of the obtained recycled plastic raw material and the constituent plastic components of the recycled plastic molded body can be increased.

  In this step, it is preferable to carry out a specific gravity selection operation for selecting plastic waste (weight crushed material) charged in the specific gravity selection liquid. Specific gravity sorting operation means that plastic waste (weight crushed material) is put into a specific gravity sorting liquid stored in a container such as a mixing and stirring tank, and has a specific gravity smaller than the specific gravity of the specific gravity sorting liquid. Alternatively, it refers to a series of operations for recovering plastic waste material floating on the surface of the specific gravity sorting liquid using a method such as an overflow method. Plastic waste having a specific gravity greater than the specific gravity of the specific gravity sorting liquid settles toward the bottom of the container, and these can be collected by a screw conveyor or the like.

  The specific gravity of the specific gravity sorting liquid varies depending on how the plastic waste material is sorted. For example, when sorting plastic waste into plastic waste mainly containing polyolefin-based plastics and plastic waste mainly containing other types of plastics, the specific gravity of the specific gravity sorting liquid is preferably 0.92 or more. 0.95 or more is more preferable. In this case, the specific gravity of the specific gravity sorting liquid is preferably 1.01 or less, and more preferably 1.00 or less. When the specific gravity of the specific gravity sorting liquid is less than 0.92, a part of the plastic waste mainly containing polyolefin-based plastics tends to settle and the recovery rate tends to decrease. Since plastic waste mainly containing polyolefin plastics floats on the specific gravity sorting liquid, the desired sorting is achieved.

  In addition, for example, plastic waste is changed into plastic waste mainly containing polyolefin plastic and plastic waste mainly containing polystyrene plastic, and plastic waste mainly containing other types of plastic other than polyolefin plastic and styrene plastic. In the case of sorting, the specific gravity of the specific gravity sorting liquid is preferably 1.00 or more, and more preferably 1.01 or more. In this case, the specific gravity of the specific gravity sorting liquid is preferably 1.10 or less, and more preferably 1.08 or less. When the specific gravity of the specific gravity sorting liquid is less than 1.00, a part of the plastic waste mainly containing polyolefin plastic tends to settle and mix, and the specific gravity of the specific gravity sorting liquid is 1.10. If it exceeds the limit, polyamide plastic, polycarbonate plastic, rubber and the like will surface and tend to be mixed into plastic waste mainly containing polyolefin plastic and plastic waste mainly containing polystyrene plastic. By using a specific gravity sorting liquid having a specific gravity within such a range, plastic waste mainly containing other types of plastics other than polyolefin plastics and polystyrene plastics settles. Sorting is achieved. The specific gravity sorting liquid having a specific gravity within such a range is not particularly limited, but a solution in which sodium chloride is dissolved in water can be suitably used. Moreover, you may make it use the solution which melt | dissolved other inorganic substances (calcium chloride etc.) as a specific gravity selection liquid in this case.

  In addition, plastic waste is classified into plastic waste mainly containing polyolefin plastics, plastic waste mainly containing polystyrene plastics, and plastic waste mainly containing other types of plastics other than polyolefin plastics and polystyrene plastics. When sorting, it is preferable to perform the specific gravity sorting operation twice. In this case, the order of specific gravity sorting operation is not particularly limited, but first, a plastic waste material mainly containing polyolefin-based plastic and polystyrene using a specific gravity sorting liquid having a specific gravity of 1.00 or more and 1.10 or less. After sorting into plastic waste mainly containing plastics and plastic waste mainly containing other types of plastics other than polyolefin plastics and polystyrene plastics, the specific gravity is 0.92 or more and 1.01 or less. It is preferable to use a liquid to sort into plastic waste mainly containing polyolefin plastic and plastic waste mainly containing polystyrene plastic. By sorting in this order, the specific gravity sorting liquid (salt water) used the first time adheres to the plastic waste material, but by supplying water in the second process, the specific gravity sorting liquid accumulates, and the plastic There is an advantage that sodium chloride hardly adheres to the waste material.

[11] Specific gravity sorting liquid separating step In the specific gravity sorting step (step 110), the plastic waste material sorted by the plastic component system and the specific gravity sorting liquid are separated (step 111). Specifically, after the specific gravity sorting process described above, plastic waste (crushed material) is discharged together with the specific gravity sorting liquid, solid-liquid separation is performed using a centrifugal dehydrator, etc., and the specific gravity sorting liquid is separated with a strainer. To do. In the plastic waste recycling method of the present invention, the specific gravity sorting liquid separated in the specific gravity sorting liquid separation step is returned to the specific gravity sorting step (step 110) and circulated. Since this specific gravity sorting liquid is applied to plastic waste material (plastic crushed material) that has undergone a cleaning process, it is less contaminated. For this reason, the specific gravity sorting liquid can be circulated using an inexpensive apparatus, and a method of separating each plastic system at a low cost can be provided. The method for recycling plastic waste material according to the present invention is characterized in that the specific gravity sorting liquid is circulated as described above, and a new specific gravity sorting liquid is supplied to the specific gravity sorting step while circulating the specific gravity sorting liquid. Of course, it is possible.

  Here, FIG. 2 is a perspective view schematically showing a swirl flow generator 1 that is suitably used in the specific gravity sorting liquid separation step in the plastic waste material recycling method of the present invention. The specific gravity sorting liquid separated from the plastic waste material in the specific gravity sorting liquid separation step is preferably stored in a storage tank once using a swirl flow generator 1 as shown in FIG. (Suspended Solids) is sent to the strainer 4. Since many SS floats on the specific gravity sorting liquid, it is preferable to forcibly also send what floats on the specific gravity sorting liquid from the suction port of the pump 2. In the swirling flow generator 1 of the example shown in FIG. 2, a sheet metal 3 having a height of about 400 mm and an angle of 30 degrees in the same direction with respect to the circumference concentrically at the suction port of the pump 2 is set at 12 intervals. The sheet is arranged and about 50 mm on the upper end side is arranged above the liquid surface of the specific gravity sorting liquid so that a swirling flow is generated in the specific gravity sorting liquid in the storage tank.

  Here, as the strainer 4, it is preferable to use a strainer that is arranged at an inclination of about 70 degrees and can operate continuously. Further, the foreign matter separated from the specific gravity sorting liquid falls by its own weight when a certain amount of foreign matter accumulates. The foreign matter is received by a wire mesh having an opening of about 100 μm, and the aqueous solution is discarded. If the crushed material does not contain halogen or metal, it may be used as fuel. Further, the opening amount (mesh size) of the strainer 4 is preferably about 300 μm because it operates stably without clogging and can recover scraps and dirt when crushed. The specific gravity sorting liquid passes through the mesh of the strainer 4, returns to the storage tank or another storage tank, and then returns to the apparatus for performing the specific gravity selection process using a pump or the like to be circulated. When only the strainer 4 is used, there is no problem even if about 80 to 95% of the specific gravity sorting liquid with respect to the processing amount is circulated and used.

  Further, when the specific gravity sorting solution is circulated, it is preferable to use a centrifuge (centrifugation type SS removing device). Preferably, a strainer and a centrifuge are used in combination, and first, a large foreign matter is removed by the strainer, and then a small amount of foreign matter is removed using a centrifugal SS removing device having an opening (mesh size) of about 20 μm. To. In this case, there is no problem even if about 95% or more of the specific gravity sorting liquid with respect to the processing amount is recycled.

  Thus, it is preferable that the plastic waste material recycling method of the present invention further includes a foreign matter removing step for removing foreign matter, and this foreign matter removing step is performed by a strainer and / or a centrifugal separator in the specific gravity sorting liquid separating step as described above. It can carry out suitably by using a separator (centrifugation type SS removing device).

  Moreover, in the plastic waste material recycling method of the present invention, it is preferable to supply the specific gravity sorting liquid after being used in the specific gravity sorting process as the cleaning liquid in the washing process. That is, the specific gravity selection liquid is supplied to a container for performing the specific gravity selection process, and the specific gravity selection liquid overflowed from the container is supplied as a cleaning liquid to the container for storing the cleaning liquid and used for the cleaning process, from the container for storing the cleaning liquid. By discarding the overflowed cleaning liquid (FIG. 1), the specific gravity sorting liquid can be used without waste.

  In the plastic waste material recycling method of the present invention, it is preferable to rinse the plastic waste material with a specific gravity sorting liquid after the cleaning liquid separation step (step 109). Specifically, it is preferable that the specific gravity sorting liquid separated from the plastic waste material in the specific gravity sorting liquid separation step is sprayed on the plastic waste material after the cleaning liquid separation step in the form of a shower to perform rinsing. Thereby, dirt can be further removed from the plastic waste material before being subjected to the specific gravity sorting process, and the specific gravity sorting liquid used in the specific gravity sorting process can be prevented from being stained.

[12] Molded body manufacturing process Next, among the plastic waste materials (crushed materials) separated for each of the plastic component systems described above, plastic waste materials (crushed materials) to be recycled are molded, and recycled plastic raw materials and / or A recycled plastic molding is manufactured (step 112). Plastic waste materials to be recycled are all types of plastic waste materials selected in the specific gravity sorting step (step 110) (for example, plastic waste materials mainly containing polyolefin-based plastics, plastic waste materials mainly containing polystyrene-based plastics, Plastic waste materials mainly including other types of plastics other than polyolefin plastics and polystyrene plastics), and some types of plastic waste materials may also be used. When recycling a plurality of plastic waste materials, a specific gravity sorting liquid separation step (step 111) is performed separately.

  As a method for producing a recycled plastic raw material and / or a recycled plastic molded body, a method in which a plastic waste material to be recycled is heated and melted and then molded as necessary. Here, when the melting point of the plastic waste material is T ° C, the temperature at the time of heating and melting is preferably T ° C or higher, and more preferably (T + 10) ° C or higher. Further, the temperature at the time of heating and melting is preferably (T + 120) ° C. or less, and more preferably (T + 80) ° C. or less. When the temperature at the time of heating and melting is less than T ° C., the plastic waste material does not sufficiently melt and tends to be difficult to mold. When the temperature at the time of heating and melting exceeds (T + 120) ° C., the plastic waste material is It tends to heat deteriorate. In addition, during heating and melting, additives such as a heat stabilizer, a light stabilizer, an antistatic agent, a lubricant, a filler, a copper damage inhibitor, an antibacterial agent, and a colorant may be added in a range that does not impair the effects of the present invention, if necessary. You may add by quantity.

  A recycled plastic raw material can be obtained by forming the plastic waste material heated and melted into, for example, pellets. However, the shape of the molded recycled plastic raw material is not particularly limited, and may be in the form of pellets, for example, in the form of sheets, films, pipes, etc. It selects suitably from an aspect or the characteristic calculated | required. The shape of the recycled plastic raw material is preferably a pellet because it has versatility as a raw material to be molded into various molded products such as sheets, films and injection molded products, and is easy to handle.

  When the recycled plastic raw material is formed into a pellet, the particle size is not particularly limited, but is preferably 1 mm or more, and more preferably 2 mm or more. This is because when the particle size of the pellet is less than 1 mm, it floats and the workability tends to be lowered. The particle size of the pellet is preferably 8 mm or less, and more preferably 5 mm or less. This is because, when the particle size of the pellets exceeds 8 mm, the pellets are not sufficiently melted in the cylinder of the molding machine and thus tend not to be uniformly kneaded.

  When forming into a pellet form, methods such as sheet cutting, strand cutting, hot air cutting, underwater cutting, and the like can be used. Among these methods, when molding into a specific shape by injection molding later, an underwater cut that can smoothly supply a recycled plastic raw material and can cope with a large amount of processing is particularly preferable.

  Thus, the plastic waste material recycling method of the present invention can also be used as a method for producing recycled plastic raw materials, and the obtained recycled plastic raw materials are also included in the present invention.

  You may make it shape | mold the recycled plastic raw material mentioned above to a plastic member, for example. Such a plastic member, which is a recycled plastic molded article of the present invention, can be suitably used for products selected from an air conditioner, a television (including a flat-screen television), a refrigerator, a washing machine, and a microwave oven.

  The recycled plastic member can be molded from the above-mentioned recycled plastic raw material using a method such as injection molding. The injection molding machine used at this time is not particularly limited, and examples thereof include a screw inline type injection molding machine and a plunger type injection molding machine.

  Also, in order to simplify the production of recycled plastic members, plastic waste materials are directly put into an injection molding machine without producing recycled plastic raw materials having shapes such as pellets, and recycled plastic members are directly produced. It doesn't matter. At this time, the recycled plastic member does not impair the effects of the present invention, if necessary, with additives such as a heat stabilizer, light stabilizer, antistatic agent, lubricant, filler, copper damage inhibitor, antibacterial agent, and coloring agent. You may add and shape | mold after manufacturing in the quantity within the range. When these additives are added, they are preferably added when the plastic waste material is put into an extruder or an injection molding machine.

  The plastic waste material recycling method of the present invention and the recycled plastic raw material and the recycled plastic molded body obtained by the method have been described above with reference to FIG. 1, but the plastic waste material recycling method of the present invention is The above-described cleaning process (step 108), cleaning liquid separation process (step 109), specific gravity selection process (step 110), and specific gravity selection liquid separation process (step 111) are essential processes, and separated in the specific gravity selection liquid separation process. Any method that circulates the specific gravity selection liquid to the specific gravity selection step may be used. Therefore, processes not shown in FIG. 1 may be added if necessary, or may be deleted if necessary, and the order of processes other than the essential processes described above is changed. Also good.

  Hereinafter, although an example of an experiment is given and the present invention is explained in detail, the present invention is not limited to these.

<Experimental Examples 1-5>
As Experimental Examples 1 to 5, according to the flowchart shown in FIG. 1, the crushed plastic (polypropylene) obtained up to the air separation process (step 107) was subjected to the presence or absence of the cleaning process and the strainer under the conditions shown in Table 1. In each case of presence or absence of rinsing, presence or absence of rinsing, and presence or absence of a centrifuge, a washing process, a washing liquid separation process, a specific gravity sorting process and a specific gravity sorting liquid separation process were carried out (no washing process for Experimental Example 1). An experiment was conducted in which the amount of contamination in the plastic was measured. The amount of contamination in the plastic is determined by extruding the recovered polypropylene and making the whole uniform, then pressing it into a sheet-like material having an area of 400 cm ² and a thickness of 0.3 mm. It was measured by counting with.

  In Experimental Examples 2 to 5, the overflow of the newly input specific gravity sorting liquid was supplied to the cleaning process as a cleaning liquid, and the cleaning liquid overflowed in the cleaning process was discarded. In Experimental Examples 3 to 5, a strainer having an opening of 300 μm was used, and in Experimental Example 5, a centrifugal separator (centrifugation-type SS removing device) having an opening of 20 μm was used to separate specific gravity by solid-liquid separation. A specific gravity sorting liquid in a storage tank for storing the liquid was pumped, and after removing foreign matter, a method of returning to a container for performing a specific gravity sorting process was adopted. In the rinsing process performed in Experimental Examples 4 and 5, the amount obtained by adding the input amount of the new specific gravity sorting liquid and one-tenth of the input amount of the crushed material between the inlet and outlet of the vibrating sieve is showered. (When solid-liquid separation (cleaning liquid separation process) is performed with a vibrating sieve, the cleaning liquid that is 1/10 of the amount of the plastic crushed material is transferred to the next process together with the plastic crushed material) .

FIG. 3 is a graph showing the results of Experimental Examples 1 to 5, where the vertical axis represents the amount of contamination (pieces / 100 cm ² ), and the horizontal axis represents the amount of new specific gravity sorting liquid input (a) and the amount of plastic crushed material input ( It is a ratio (a / b) to b). Here, the ratio (a / b) shown on the horizontal axis indicates that the larger the value, the larger the input amount (a) of the new specific gravity sorting liquid. The input amount (b) of the plastic crushed material for one experiment was 10 t, and the specific gravity sorting solution was changed for each experiment.

  As shown in FIG. 3, in the case of no washing (Experimental Example 1), many new specific gravity sorting liquids are required to reduce contamination. For this reason, it turns out that the input (a) of the novel specific gravity sorting liquid for reducing contamination can be reduced by performing a washing process. Furthermore, in the case where foreign matters are removed through the strainer (Experimental Examples 3 to 5), the input amount (a) of the new specific gravity sorting liquid is further increased as compared with the case where the strainer is not passed (Experimental Examples 1 and 2). It can be seen that it can be reduced. In addition, when a rinsing step is added (Experimental Examples 4 and 5), the input amount (a) of the new specific gravity sorting liquid can be further reduced, and when a strainer and a centrifuge are used together (Experimental Example 5). Furthermore, the input amount (a) of the new specific gravity sorting liquid could be reduced.

  It should be considered that the embodiments and experimental examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a flowchart which shows a preferable example of the recycling method of the plastic waste material of this invention. It is a perspective view which shows typically the swirl | vortex flow generator 1 used suitably for the specific gravity sorting liquid separation process in the recycling method of the plastic waste material of this invention. It is a graph which shows the result of Experimental Examples 1-5, a vertical axis | shaft is the amount of contamination (pieces / 100cm < ² >), and a horizontal axis is the input amount (a) of a novel specific gravity sorting liquid, and the input amount (b) of a plastic crushed material. Ratio (a / b).

Explanation of symbols

  1 Swirling flow generator, 2 pump, 3 sheet metal, 4 strainer.

Claims (14)

A cleaning process for cleaning plastic waste containing multiple types of plastics with different specific gravity with a cleaning solution;
A cleaning liquid separating step for separating the plastic waste material and the cleaning liquid;
A specific gravity sorting process for sorting plastic waste with a specific gravity sorting liquid based on the specific gravity difference of the plastic,
A specific gravity sorting liquid separating step for separating the sorted plastic waste and the specific gravity sorting liquid,
A method for recycling plastic waste that circulates the specific gravity selection liquid separated in the specific gravity selection liquid separation process to the specific gravity selection process.   The method for recycling plastic waste materials according to claim 1, wherein the cleaning liquid separated in the cleaning liquid separation step is circulated to the cleaning step.   The method for recycling plastic waste material according to claim 1 or 2, wherein the specific gravity sorting liquid and the cleaning liquid have the same composition.   The method for recycling plastic waste materials according to any one of claims 1 to 3, wherein the specific gravity sorting liquid used in the specific gravity sorting step is supplied to the washing step.   The method for recycling plastic waste materials according to any one of claims 1 to 4, wherein a new specific gravity sorting liquid is supplied to the specific gravity sorting step.   The plastic waste material recycling method according to any one of claims 1 to 5, wherein the plastic waste material is rinsed with the specific gravity sorting liquid used in the specific gravity sorting step after the cleaning liquid separation step.   The method for recycling plastic waste material according to any one of claims 1 to 6, further comprising a foreign matter removing step of removing foreign matter.   The method for recycling plastic waste materials according to claim 7, wherein the foreign matter removing step is a step of removing foreign matter using a strainer and / or a centrifuge.   The method for recycling plastic waste materials according to any one of claims 1 to 8, wherein the specific gravity separation liquid has a specific gravity of 0.92 to 1.00.   The method for recycling plastic waste materials according to any one of claims 1 to 9, further comprising an air separation step before the cleaning step.   11. The plastic waste material according to any one of claims 1 to 10, wherein the plastic waste material is separated and recovered from at least one waste selected from a television including a flat-screen television, a microwave oven, a dryer, an air conditioner, a refrigerator, and a washing machine. The method of recycling plastic waste materials described.   The recycled plastic raw material obtained by the method in any one of Claims 1-11.   The recycled plastic raw material according to claim 12, which is in a pellet form.   A plastic molded body obtained by molding the recycled plastic raw material according to claim 12 or 13, wherein at least one selected from a television including a flat-screen television, a microwave oven, a dryer, an air conditioner, a refrigerator, and a washing machine Recycled plastic molding used for plastic parts.

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