JP2008110344A - Washing process of crushed plastic and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To wash crushed plastics at a low cost while reducing the load to be imposed on the environment. <P>SOLUTION: Crushed plastics and washing water are whirled spirally in a washing tank 37, made to flow through a suction port 37c, a conveyance pipe 45, a circulation pipe 50 and a discharge port 50a and circulated through them two or more times. Stains stuck to crushed plastics and crushed powder are washed away by the friction among crushed plastics, the friction between crushed plastics and the washing tank, the air bubbles and current of washing water or the like. Minute crushed chips are discharged through a punched hole 37e and only crushed plastics having the size suitable for the remolding work are sorted during the time to wash crushed plastics in the washing tank 37. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for cleaning crushed plastic.

  Various types of lens-equipped film units that have a simple photographing mechanism and are pre-loaded with a photographic film are on the market. In recent years, plastics, which occupy a great deal of importance as a material in the growing interest in environmental issues, have become an urgent issue to promote recycling. Recycled pellets for the purpose of reducing environmental impact, saving energy, reducing costs, etc. The amount of recycled plastics such as recycled chips is rapidly increasing. Therefore, the used lens unit with a lens is collected and reused for each component or recycled as a raw material.

  Since the recycled plastics are collected from products that have been put on the market once, they are often contaminated and contaminated with foreign matter, and cannot be completely removed by various processes such as sorting and cleaning in the recycling process. Therefore, these recycled plastics are inevitably mixed with foreign matter as compared with the above-mentioned virgin plastics, and how to prevent foreign matter is an important issue in recycling.

  In the recycling line for lens-equipped film units, the collected lens-equipped film units are sorted by model and sent to the respective disassembly lines. In the disassembly line, the paper box and the label covering the outside of the lens-fitted photo film unit are removed and disassembled into each component. The disassembled component parts are separated into reuse parts that are reused through functional inspection, cleaning and adjustment, and recycled parts that are reused as raw materials, and are sent to the respective regeneration lines.

  Recycled parts are parts formed of thermoplastics. Specifically, front and back covers that cover the front and back sides of a lens-fitted photo film unit, a main body that is loaded with photographic film, and film winding It is a winding knob used for operation. These recycled parts are finely crushed by a crushing device.

  The crushed plastic is freed of dirt and foreign matter adhering thereto by a shower type washing machine to which a washing liquid is sprayed. When recycling plastic, a method has been invented in which crushing plastic and cleaning liquid are agitated in a cleaning tank to remove dirt and foreign matters (undercoat layer and printing of photographic film) and the like (for example, see Patent Documents 1 to 3). ). In addition, in order to further increase the cleaning power, contrivances such as mixing an aqueous detergent such as a surfactant into the cleaning liquid, or inclining the bottom surface of the cleaning tank and attaching a stirring blade are provided.

The crushed plastic dried after washing is heated and melted, and is formed into cylindrical pellets by a pelletizing process using an extrusion apparatus. The pellets are used alone or mixed with virgin plastic to form the front cover and rear cover of the lens-fitted film unit, the main body, and the winding knob.
Japanese Patent No. 2604262 Japanese Patent No. 2640786 Japanese Patent No. 2717020

  Analyzing the energy required in the process of pelletizing recycled parts, there is a problem that a large amount of heat energy is required in the process of melting recycled parts, the amount of power energy and water used is large, and the environmental load is large. there were.

  Further, a product using recycled plastic has a problem that strength and other physical properties of the plastic are inferior to those using virgin plastic because heat deterioration is advanced. This is because physical properties are deteriorated due to extra heating and melting for each pelletizing treatment. Further, photographic concern substances and the like may be generated by heating and melting.

  Furthermore, the shower type washing machine used for washing the crushed plastic was not very high in washing ability. For this reason, in the extrusion apparatus, a filter provided for removing foreign matters mixed in the plastic is often clogged, which causes a reduction in operating rate and workability. Also, because of the high temperature work, the filter replacement work is dangerous and complicated, and it is difficult to automate and unmanned for filter consumption, filter breakage monitoring, etc., and the semi-automatic filter changer is expensive. It was expensive.

  The above-mentioned stirring type cleaning device can be used instead of the shower cleaning device having a weak cleaning power. However, when the object to be cleaned is about the same as the cleaning liquid or lighter than the cleaning liquid, uniform stirring is difficult and predetermined cleaning is performed. I couldn't get power. In addition, an object to be cleaned that is lighter than the cleaning liquid is separated from the object to be cleaned and the cleaning liquid in the discharge after the cleaning, making it difficult to discharge efficiently.

  Further, as an example of washing a light object to be washed, a plastic bottle recycling line or the like includes a washing device that puts a plastic bottle crushed into chips into a net basket or the like and rotates it in a washing tank. However, the operations such as loading and unloading the crushed plastic into the net basket, and setting and taking out the net basket into and from the washing tank are complicated and difficult to automate, and the washing time is long and the equipment becomes complicated. There was also a problem.

  Furthermore, organic solvents, chlorofluorocarbons, surfactants, and other detergents mixed in the cleaning solution to ensure the cleaning effect have a serious problem in that the working environment is deteriorated, running costs and wastewater treatment costs are high. The impact on the environment is not negligible.

  The present invention is for solving the above-mentioned problems, and cleans the crushed plastic at a low cost and with a low environmental load.

  In the method for cleaning crushed plastic according to the present invention, the crushed plastic is circulated together with the cleaning liquid, and the cleaning liquid is in a spiral vortex state between the cleaning liquid and the crushed plastic in the circulation pipe and the cleaning tank in the middle of the circulatory flow. And the crushing plastic, and the contact between the crushing plastics is increased to improve the cleaning power. Note that air bubbles may be mixed in the cleaning liquid in the middle of the circulation of the cleaning liquid and the crushed plastic. Detergency is improved by the cavitation effect.

  In addition, the crushing plastic cleaning apparatus is provided with a substantially conical bottom portion connected to the bottom of the substantially cylindrical body, and a washing tank into which crushing plastic obtained by crushing a used plastic product and a cleaning liquid are charged. A suction port provided at the bottom of the cleaning tank through which cleaning liquid and crushed plastic flow, and an inlet on one end side are connected to the suction port, and a discharge port on the other end side is arranged along the inner surface of the cleaning tank. A circulation pipe, and a liquid feed pump for flowing the cleaning liquid and crushed plastic flowing into the suction port into the circulation pipe and discharging them from the discharge port of the circulation pipe.

  In addition, a plurality of openings through which only crushed plastic having a size less than or equal to the specified size is formed in a part of the substantially cylindrical body of the cleaning tank, and the crushed plastic having a size or smaller than the specified size is removed from the cleaning tank. Also good.

  Further, a cleaning liquid in which bubbles are mixed may be supplied to the inlet of the circulation pipe from an air supply port provided between the liquid supply pump and the inlet.

  According to the crushing plastic cleaning method and apparatus of the present invention, crushing plastic that is difficult to disperse due to normal stirring and cleaning can be efficiently cleaned in a short time. Furthermore, since a powerful detergency can be obtained only with warm water without using a detergent, waste water treatment is easy and can be carried out at a low cost. And it is easy to implement because the environmental load is low and the work environment is good. Further, since complicated mechanical parts are not used, maintenance and automation are easy.

  FIG. 1 shows an example of a lens-fitted photo film unit recycled by the recycling method of the present invention. The lens-fitted photo film unit 2 includes a unit main body 3 and a label 4 that partially covers the outer periphery of the unit main body 3. On the front surface of the lens-fitted photo film unit 2, a photographing lens 5, a finder 6, a strobe light emitting unit 7 and the like are provided. A charging operation unit 8 for strobe is provided below the strobe light emitting unit 7. A shutter button 9, a film counter window 10 and the like are formed on the upper surface of the lens-fitted photo film unit 2, and a winding knob 11 is exposed from the upper surface to the rear surface.

  As shown in FIG. 2, the unit main body 3 includes a main body base 14 in which a film cartridge 13 is loaded, a strobe unit 15 that emits strobe light, an exposure unit 16 that incorporates a photographing lens 5 and a shutter mechanism, and a main body base. 14 includes a front cover 17 and a rear cover 18 that cover the front and rear surfaces of 14.

  The used lens-equipped film unit 2 is handed over to the developing agency by the user when requesting simultaneous printing. The lens-fitted photo film unit 2 delivered to the developing agency is collected at the developing station, and the cartridge 21 containing the photographed photographic film 20 is taken out. The taken-out photographic film 20 is returned to the user after completing the development process and the printing process, and the lens-fitted photo film unit 2 is collected by the manufacturer.

  FIG. 3 is a schematic diagram showing the configuration of the recycling plant for the lens-fitted photo film unit 2. The recycling plant is a product disassembly line for disassembling the collected lens film unit 2 and a function of inspecting, cleaning, repairing, adjusting or reusing functional parts such as the strobe unit 15 and the exposure unit 16 among the disassembled parts. A parts reuse line, a plastic parts recycling line for recycling parts formed of thermoplastics such as the main body base 14, the front cover 17 and the rear cover 18 into raw materials; a main body base 14, the front cover 17 and the rear cover 18; And a molding line for molding again.

  The collected lens unit with lens 2 is sorted by product type and sent to the product disassembly line. In the product disassembly line, the label 4 attached to the surface of the lens-fitted photo film unit 2 is peeled off. Thereafter, the front cover 17 and the winding knob 11 are removed and sent to the plastic parts recycling line. The exposure unit 16 and the strobe unit 15 are removed from the main body base 14 and sent to the functional component reuse line, and those that can be reused after being inspected, cleaned, repaired or adjusted are reused. Also, the battery 23 of the flash unit 15 that can be reused after inspection is reused.

  Finally, the remaining main body base 14 and rear cover 18 are sent to a plastic parts recycling line. The front cover 17, the rear cover 18, the main body base 14, and the winding knob 11 are made of plastic parts after it is confirmed that metal parts are caught, entangled, or not left inside by the metal detector. Sent to the playback line.

  FIG. 4 is a schematic diagram showing the configuration of the plastic part recycling line. The plastic parts recycling line includes a rough crusher 24, a wind sorter 25, a fine crusher 26, a washing machine 27, a dehydrator 28, a dryer 29, a metal detector 30, and a stacking unit 31. The disassembled front cover 17, rear cover 18, main body base 14, and winding knob 11 are first fed into the rough crusher 24. In this rough crusher 24, it is preferable that the passing screen of the crushed product is about φ20 to φ60.

  The roughly crushed crushed plastic is sent to the wind power sorter 25 by a conveying device such as a loader hopper 33 using air. The transport device may be anything that can transport crushed plastic such as a conveyor or a pipe feeder, and is not limited to a loader hopper. In this wind power sorter 25, the supplied crushing plastic is blown off by wind power, and is separated into heavy crushing plastic, light label waste, photographic film waste, mixed gazette waste, paper waste, and the like. Light label waste, film waste, and the like are collected below the wind sorter 25 and discarded. The sorted crushing plastic is conveyed to the next crushing machine 26.

  In the wind sorter 25, if the relative weight difference between the crushed plastic, the label waste, and the film waste with respect to the wind force is reduced, the sorting accuracy is lowered. Therefore, it is better not to crush it too small in rough crushing. In addition, with the screen size φ35 of the coarse crusher 24, a separation accuracy of 93% or more by weight ratio was obtained.

  In the fine crusher 26, the screen size is preferably about φ4 to φ12 in order to crush to a size suitable for washing and molding, for example, a size close to a pellet (φ2 mm × 3 mm). In the examples, in order to reduce the loss of plastic and stabilize the molding, the crusher and crushing conditions were such that the generation of resin powder having a size of 1 mm or less was 10% or less. The crushed plastic that has been finely crushed is conveyed to the next washing machine 27 by the loader hopper 35.

  The lens-equipped film unit 2 is often handled more roughly than a general camera, and the collected product often has general oils, sebum, foods, cosmetics, and other various stains attached thereto. In particular, it is necessary to thoroughly remove dirt that is harmful to photographic materials. In general cleaning, organic solvents, chlorofluorocarbons, detergents, and the like are used. However, there is a problem that the working environment is deteriorated, the environmental load, the running cost, and the wastewater treatment cost are high. Cleaning with high-pressure water, surface peeling by blasting with sand, resin particles, dry ice, ultrasonic cleaning, X-ray cleaning, UV cleaning, etc. are also candidates, but these cleaning methods are automated and sufficient cleaning It was difficult to get the ability at a low cost.

  5 and 6 are a perspective view and an essential part cross-sectional view showing the appearance of the washing machine 27 used in the present invention. The washing machine 27 is provided so as to surround the washing tank 37, a water receiver 38 that receives the washing water 39 overflowing from the washing tank 37, and a hot water tank 40 that stores the washing water 39. The liquid feed pump 41 conveys the washing water 39 in the hot water tank 40, the circulation pipe 43 through which the washing water 39 and the crushed plastic 44 circulate, and the draining basket 42.

  The cleaning tank 37 into which the cleaning water 39 and the crushed plastic 44 are charged is composed of a substantially cylindrical body part 37a and a substantially conical bottom part 37b provided below the body part 37a. In the center of the bottom 37b of the cleaning tank 37, a suction port 37c through which crushed plastic and cleaning water 39 flow is provided. In addition, a connection pipe 37d that constitutes the circulation pipe 43 is provided at the suction port 37c.

  One end of the transfer pipe 45 constituting the circulation pipe 43 is connected to the connection pipe 37 d of the cleaning tank 37, and the other end is connected to a substantially T-shaped branch pipe 49. The other two ends of the branch pipe 49 are connected to a circulation pipe 50 that forms a circulation pipe 43 and a discharge pipe 51 that faces the draining basket 42. The discharge port 50a at the tip of the circulation pipe 50 is inserted into a hole 37f formed in the side surface of the cleaning tank 37, and is disposed at a position closer to the inner wall surface.

  In the branch pipe 49, a switching valve for switching the flow path from the transport pipe 45 and selectively connecting to the circulation pipe 50 and the discharge pipe 51 is incorporated. This switching valve is switched by an operation lever 52 provided outside the branch pipe 49.

  In the hot water tank 40, cleaning water 39 used for cleaning is stored and heated by a heater. The liquid feed pump 41 has a suction port connected to the hot water tank 40 by a suction pipe 46a, and a discharge port connected to the transport pipe 45 by a discharge pipe 46b. The liquid feed pump 41 sucks the wash water 39 from the hot water tank 40 and flows it into the transport pipe 45. A nozzle that increases the flow rate of the cleaning water 39 is incorporated in a connection portion to the transport pipe 45 at the end of the discharge pipe 46b. As a result, a negative pressure is generated in the transport pipe 45, and the crushed plastic 44 and the cleaning water 39 put in the cleaning tank 37 are sucked and poured into the transport pipe 45.

  The discharge pipe 46 that connects the liquid feed pump 41 and the transport pipe 45 is provided with an air supply port 47 that takes air into the pipe and mixes bubbles into the cleaning water 39. The bubbles mixed in the cleaning water 39 improve the cleaning power by the cavitation effect.

  The cleaning water 39 and the crushed plastic 44 transported through the transport pipe 45, the branch pipe 49, and the circulation pipe 50 are poured into the cleaning tank 37 from the discharge port 50a. The cleaning water 39 and the crushed plastic 44 poured into the cleaning tank 37 hit the inner wall surface of the cleaning tank 37 because the discharge port 50 a is located near the inner wall surface of the cleaning tank 37.

  The body 37a of the cleaning tank 37 is disposed above the water receiver 38, and the portion of the circulation pipe 50 that faces the discharge port 50a is formed by a punch plate 37e. Since the punch plate 37e has a punch hole of about φ1 mm, for example, the cleaning water 39 containing plastic pieces, plastic powder, and dirt crushed smaller than the standard by the fine crusher 26 is removed from the punch plate 37e. It is discharged out of the washing tank 37 through.

  The washing water that has flowed out of the punch plate 37e of the washing tank 37 is received by the water receiver 38. Since the water receiver 38 is provided with an outflow path 38a through which the cleaning water 39 flows into the hot water tank, the cleaning water 39 is stored in the hot water tank 40 again. In addition, since the wire mesh filter 54 which filters the washing water 39 poured from the water receiver 38 is arranged in the upper part of the hot water tank 40, small crushed pieces and crushed powder that have passed through the punch plate 37e are contained in the hot water tank 40. Do not flow.

  As shown in FIG. 7, which is a plan view of the cleaning machine 27, the cleaning water 39 and the crushed plastic 44 that have returned to the cleaning tank 37 and the momentum when discharged from the discharge port 50 a and the bottom 37 b of the cleaning tank 37. Due to the inclination, for example, it flows down to the suction port 37c while spirally turning counterclockwise. The washing water 39 and the crushed plastic 44 that have flowed into the suction port 37c are again sucked by the negative pressure in the transport pipe 45 and circulate in the circulation pipe 43 together with the pressure-feed water fed from the liquid feed pump 41.

  The crushing plastic 44 is repeatedly circulated between the washing tank 37 and the circulation pipe 50 by the washing water 39. At this time, friction between the crushing plastics 44, the punching plate 37e of the crushing plastic 44 and the washing tank 37, Dirt and crushed powder adhering to the crushed plastic 44 are washed away by the friction, bubbles and flow of the washing water 39, and the like. Thereby, it is sufficiently cleaned without using an organic solvent, chlorofluorocarbon, detergent or the like. In addition, since cleaning is performed only with warm water, the working environment is hardly deteriorated, and the environmental load, running cost, and wastewater treatment cost can be reduced. The temperature of the washing water varies depending on the conditions, and washing is possible even at a lower temperature.

  In addition, the suction port 37c of the cleaning tank 37 is preferably not partially blocked by the cleaning water 39 and the crushed plastic 44, but is partially opened. Since the washing water 39 and the crushed plastic 44 are stably sucked into the transport pipe 45 together with air, the suction port 37c is less likely to be clogged, so that the washing water 39 and the crushed plastic 44 remaining in the washing tank 37 are stable. A spiral flow can be formed. When a stable spiral flow is formed in the cleaning tank 37, the retention in the cleaning tank 37 hardly occurs, and the cleaning efficiency and the circulation efficiency are improved. If a baffle plate is attached near the suction port 37c and a part of the spiral flow is branched and adjusted to flow directly into the suction port, the suction becomes more efficient.

  Furthermore, in order to form a stable spiral flow, the pump pressure of the liquid feed pump 41, the amount of pumped water (adjustment of the pump pressure or valve adjustment during piping), the position of the discharge port 50a of the circulation pipe 43, the discharge amount, The amount of cleaning water 39 returned to the cleaning tank 37 and the amount of crushed plastic 44 are adjusted by appropriately adjusting the collision angle and pressure to the punch plate 37e, the area of the punch plate 37e, the hole diameter and the opening ratio of the punch plate 37e, etc. Must be allocated appropriately. It is also important to ensure a flow pressure above a certain level.

  Further, the state of the spiral flow is also related to the inclination angle of the bottom 37b of the cleaning tank 37 and the characteristics of the cleaning liquid. In this embodiment, warm water is used as the cleaning liquid. However, other cleaning liquids having different specific gravity and viscosity have different conditions for creating a stable spiral flow, and therefore it is necessary to newly set conditions.

  In order to improve the circulation efficiency with respect to the washing tank 37, a fixed baffle plate may be attached to the inside of the washing tank 37, and a part of the spiral flow may be branched and directly poured into the suction port 37c.

  When the predetermined number of circulations are completed or a predetermined time has elapsed and the crushing plastic 44 has been cleaned, the operation lever 52 is operated and the switching valve is switched to the discharge pipe 51 side. Thereby, the crushed plastic 44 is poured into the discharge pipe 51. The tip of the discharge pipe 51 is installed in a draining basket 42 formed of a wire mesh or a punch plate, and the crushed plastic 44 is separated from the washing water 39 in the draining basket 42.

  The washed crushed plastic stored in the draining basket 42 is fed into the dehydrator 28 by, for example, a conveyor or a pipe feeder 56. This dehydrator is, for example, a centrifugal dehydrator, and removes the washing water 39 adhering to the crushed plastic so that the water content becomes 2% or less, for example. In addition, as long as it can convey, the conveyance apparatus of the code | symbol 33, 35, 58, 60, 61 of a schematic diagram may be other than loader hopper, for example, conveyance piping by air pressure feeding or suction.

  The dewatered crushed plastic is conveyed to the dryer 29 by a loader hopper 58. Various methods such as a steam method, an electric heating method, a microwave method, and a light heating method can be considered as the drying method, but the dryer 29 here blows the drying air heated by the heater onto the crushed plastic with a blower, Wash water 39 is evaporated.

  The dried crushed plastic is conveyed to the metal detector 30 by the loader hopper 60. The metal detector 30 detects and separates metal pieces from the crushed plastic using eddy current. The crushed plastic after the metal separation is accumulated in the accumulation unit 31 by the loader hopper 61. Here, if a magnet is inserted in front of the metal detector 30 to perform preliminary sorting of the iron-based metal, the separation efficiency by the metal detector 30 is improved. When this magnet is installed in a process other than the metal detector 30, the metal removal efficiency is further improved.

  The crushed plastic stored in the accumulation unit 31 is conveyed to a molding line, and is molded into resin parts such as the front cover 17 and the rear cover 18, the main body base 14, and the winding knob 11. As shown in FIG. 8, a nozzle 65 for pouring heated and melted plastic into a mold 66 is attached to the tip of an injection molding machine 64 used for this injection molding.

  The nozzle 65 includes a substantially cylindrical nozzle case 68 attached to the injection molding machine 64, a nozzle head 69 attached to the tip of the nozzle case 68 and pressed against the mold 66, and a first incorporated in the nozzle case 68. It comprises a cap 70 and a second cap 71, a conversion shaft 72 for switching the plastic inflow path, and a filter 73.

  As shown in FIG. 9, the filter 73 has a small number of small-diameter holes 73a formed on the outer peripheral surface of a thin metal plate formed in a cylindrical shape. The filter 73 is made of super-strength steel in order to obtain a pressure strength that is not destroyed by the maximum cylinder pressure of the injection molding machine 64, and has a thickness t of about 2 mm.

  The hole 73a has a diameter d of, for example, 0.2 mm with reference to a wire mesh filter of about # 200 used in a conventional pellet molding extruder. In this case, the (thickness / hole diameter) ratio is about 10 times. The hole pitch p is set to 0.5 mm, which is close to the limit of hole formation. At this time, if the filter 73 has an outer diameter D of 45 mm, a length L of 30 mm, and an aperture ratio of 11%, the number of holes is 15414. The total opening area of these holes corresponds to a hole area of φ24.8 mm, and is larger than the resin flow area of a general injection molding machine or a mold. It becomes a level without a problem.

  The hole 73a of the filter 73 is difficult to form by ordinary drilling in consideration of the hole diameter, pitch, number of holes, wall thickness, filter shape, etc., hole accuracy, processing time, cost, and the like. . Although laser processing can be applied, laser processing has low power at the moment, and it takes time to make a hole. Therefore, adjacent holes are thermally deformed and distorted, and cannot be formed with high accuracy.

  In the present embodiment, the processing can be performed with high accuracy and efficiency by using electron beam processing capable of instantaneous high energy processing by narrowing the beam to a minute diameter. In electron beam machining, the hole shape can be tapered by adjusting the machining conditions. As shown in FIG. 10, the hole 73a of the filter 73 has a tapered shape in which the inner hole diameter d2 is smaller than the outer hole diameter d, and the taper degree is 20%.

  At the time of injection molding, the molten plastic supplied from the injection molding machine 64 is poured into the inflow portion 68 a at the rear end of the nozzle case 68. The molten plastic poured into the inflow portion 68a presses the conversion shaft 72 and slides toward the nozzle tip. As a result, the first connection path 72 a formed at the rear end of the conversion shaft 72 is connected to the central path 70 a of the first cap 70. The molten plastic flowing out from the first cap 70 passes through the hole 73a of the filter 73 and flows out from the inside of the filter 73 to the outside. At that time, the foreign matter mixed in the molten plastic is caught in the hole 73a of the filter 73, stays inside the filter 73, and is removed from the plastic to be injection molded.

  The molten plastic that has passed through the filter 73 flows into the nozzle head 69 through the outer peripheral path 71 a of the second cap 71. The molten plastic that has flowed into the nozzle head 69 passes through the nozzle path 69 a and is pressed into the mold 66.

  Further, when the filter 73 of the nozzle 65 is clogged and the pressure loss becomes large, the cause of the pressure loss and clogging can be eliminated by cleaning the filter 73 without disassembling the nozzle 65. As shown in FIG. 11, when cleaning the filter 73, the cleaning nozzle 75 a of the cleaning plunger 75 is inserted into the nozzle path 69 a of the nozzle head 69, and the cleaning plunger 75 is pressed against the mold 66. The cleaning nozzle 75a presses the conversion shaft 72 at its tip and slides it toward the molding machine main body.

  The first connection path 72 a is connected to the outer peripheral path 70 b of the first cap 70 by sliding the conversion shaft 72 toward the molding machine main body. Thereafter, when molten plastic is poured from the injection molding machine 64, the molten plastic flows outside the filter 73 through the outer peripheral path 70 b of the first cap 70. And it flows into the inside of the filter 73, eliminating the clogging of the hole 73a of the filter 73. The molten plastic that has flowed into the filter 73 passes through the second connection path 72b at the tip of the conversion shaft 72, flows into the cleaning nozzle 75a of the cleaning plunger 75, and is discharged from the discharge port 75b.

  Thereby, since the filter 73 can be cleaned without disassembling the nozzle 65, the time until returning to work can be shortened. Further, since the cleaning can be performed only by inserting the cleaning plunger 75, dangerous and complicated operations can be reduced.

  The smaller the hole diameter of the filter 73, the better the foreign matter removing performance. However, the processing becomes difficult and costly, and an increase in pressure loss during molding becomes a problem. The filter 73 may be formed by joining a plurality of wire meshes by welding, sintering, pressing, etc., in addition to forming a hole in a thin metal plate, or by using a sintered metal or porous material having a filter effect. Applications such as ceramics and metal screens may also be used.

  Next, the operation of the above embodiment will be described. The lens-fitted photo film unit 2 shown in FIGS. 1 and 2 is collected after use by the user and sent to the recycling plant shown in FIG. The lens-fitted photo film units 2 sent to the recycling plant are sorted by product type and sent to the product disassembly line of each model.

  In the product disassembly line, the label 4 attached to the surface of the lens-fitted photo film unit 2 is peeled off. Thereafter, the front cover 17 and the winding knob 11 are removed and sent to the plastic parts recycling line. The exposure unit 16 and the strobe unit 15 are removed from the main body base 14, and sent to the functional component reuse line, and those that can be reused after inspection, cleaning, repair, or adjustment are reused. Also, the battery 23 of the flash unit 15 that can be reused after inspection is reused.

  Finally, the remaining main body base 14 and rear cover 18 are sent to a plastic parts recycling line. The front cover 17, the rear cover 18, the main body base 14, and the winding knob 11 are made of plastic parts after it is confirmed that metal parts are caught, entangled, or not left inside by the metal detector. Sent to the playback line.

  The front cover 17, the rear cover 18, the main body base 14, and the winding knob 11 sent to the plastic part recycling line shown in FIG. 4 are first sent to the rough crusher 24. The rough crusher 24 crushes each part with a roughness of about 20 to 60 mm.

  The roughly crushed crushed plastic is sent to the wind power sorter 25 by the loader hopper 33. In the wind power sorter 25, the supplied crushing plastic is blown off by wind power, and is separated into heavy crushing plastic, light label waste, photographic film waste, mixed gazette waste, paper waste, and the like. Light label waste, film waste, and the like are collected below the wind sorter 25 and discarded. The sorted crushing plastic is conveyed to the next crushing machine 26.

  The fine crusher 26 crushes the plastic parts roughly crushed by the coarse crusher 24 into a size of 4 to 12 mm suitable for cleaning and molding. The fine crushed plastic 44 crushed by the fine crusher 26 is conveyed to the next washing machine 27 by the loader hopper 35. The crushed plastic sent to the washing machine 27 is stored in a fixed amount by a fixed amount hopper installed above the washing machine 27.

  In the washing machine 27, before putting the crushed plastic 44, 200 liters of washing water 39 heated to 60 ° C. is put into the washing tank 37, and the liquid feed pump 41 is operated. Then, while the cleaning water 39 is circulating between the cleaning tank 37 and the circulation pipe 43, the bottom valve of the metering hopper is opened, and 20 kg of crushed plastic 44 is put into the cleaning tank 37. As a result, the washing water 39 and the crushed plastic 44 can be easily combined, and a stable circulating flow can be formed.

  As a method for charging the crushing plastic 44 into the washing tank 37, the crushing plastic 44 can be put into the washing tank 37 and then the liquid feed pump 41 can be operated to circulate the washing water 39. However, since the plastic is water repellent and has a mold release agent adhering to the surface, it is difficult to blend with the washing water 39, and the washing water 39 and the crushing plastic 44 are not mixed well, and only the crushing plastic 44 is retained. As a result, the suction port 37c may be blocked, and a stable circulation flow may not be formed. As a countermeasure against this problem, after the crushed plastic 44 is charged, the washing tank 37 is filled with the washing water 39 and immersed for a predetermined time, and then the liquid feed pump 41 is operated.

  The liquid feed pump 41 sucks the washing water 39 warmed from the hot water tank 40 through the suction pipe 46a, and sends the washing water 39 into the transport pipe 45 through the discharge pipe 46b. At this time, since a negative pressure is generated in the transport pipe 45, the crushed plastic 44 stored in the cleaning tank 37 is sucked into the suction port 37 c together with the cleaning water 39 and is poured into the transport pipe 45. The crushed plastic 44 fed into the transport pipe 45 is fed into the circulation pipe 50 through the branch pipe 49 by the flow of the washing water 39, and is vigorously discharged into the washing tank 37 from the discharge port 50a.

  The cleaning water 39 and the crushed plastic 44 poured into the cleaning tank 37 hit the inner wall surface of the cleaning tank 37 and are discharged from the discharge port 50a because the discharge port 50a is located near the inner wall surface of the cleaning tank 37. Due to the momentum and the inclination of the bottom 37b of the cleaning tank 37, it flows down to the suction port 37c while spirally turning counterclockwise. The wash water 39 and the crushed plastic 44 that have flowed into the suction port 37 c are again sucked by the negative pressure in the transport pipe 45, and are circulated into the circulation pipe 43 together with the pressure feed water sent from the liquid feed pump 41. Poured.

  The crushing plastic 44 is repeatedly circulated between the washing tank 37 and the circulation pipe 50 by the washing water 39. At this time, friction between the crushing plastics 44 and friction between the crushing plastic 44 and the punch plate 37e of the washing tank 37 are performed. The dirt and crushed powder adhering to the crushed plastic 44 are washed away by the bubbles and flow of the washing water 39. Further, since air bubbles are generated in the cleaning water 39 by the air supply port 47 provided in the discharge pipe 46, the cleaning power is further improved by the cavitation effect.

  Of the washing water 39 and the crushing plastic 44 poured into the washing tank 37, the washing water 39 containing plastic pieces, plastic powder, and dirt crushed smaller than the standard by the crushing machine 26 is a punch plate. It is discharged out of the cleaning tank 37 through 37e. The washing water flowing out from the punch plate 37e is received by the water receiver 38, flows through the outflow passage 38a, and flows into the hot water tank 40. Small plastic pieces and plastic powder are filtered by a wire mesh filter 54 provided in the upper part of the hot water tank 40, and only the washing water 39 is collected in the hot water tank 40.

  When the predetermined number of circulations are completed or the cleaning of the crushed plastic 44 is completed after a predetermined time has elapsed, the operation lever 52 is operated and the switching valve is switched to the discharge pipe 51 side. Thus, the crushed plastic 44 is poured into the draining basket 42 through the discharge pipe 51 and separated from the washing water 39.

  If the specific gravity of the crushed plastic is smaller than that of the washing water, it will rise to the upper part by normal stirring, and the dispersion with respect to the washing water will be poor, so that a sufficient washing effect cannot be expected. However, in the present invention, since the flow is sequentially poured into the circulation pipe by the spiral flow, effective cleaning can be performed without causing separation from the wash water in the circulation pipe.

  The washed crushed plastic 44 stored in the draining basket 42 is sent to the dehydrator 28 by the pipe feeder 56. This dehydrator is, for example, a centrifugal dehydrator, and removes the washing water 39 adhering to the crushed plastic so that the water content becomes 2% or less, for example. The dewatered crushed plastic is conveyed to the dryer 29 by a loader hopper 58. In the dryer 29, the drying air heated by the heater is blown onto the crushed plastic 44 by a blower, and the washing water 39 is evaporated.

  The dried crushed plastic is conveyed to the metal detector 30 by the loader hopper 60. The metal detector 30 detects and separates metal pieces from the crushed plastic 44 using eddy currents. The crushed plastic 44 after the metal separation is accumulated in the accumulation unit 31 by the loader hopper 61.

  The crushed plastic 44 stored in the stacking unit 31 is conveyed to a molding line. The crushed plastic 44 is put into a heating cylinder of an injection molding machine 64 installed in a molding line, and is melted by shear heating of a screw in the heating cylinder and heating of a heater.

  The melted plastic is poured into the inflow portion 68 a at the rear end of the nozzle case 68 by the injection molding machine 64. The molten plastic poured into the inflow portion 68a presses the conversion shaft 72 and slides toward the nozzle tip. As a result, the first connection path 72 a formed at the rear end of the conversion shaft 72 is connected to the central path 70 a of the first cap 70. The molten plastic flowing out from the first cap 70 passes through the hole 73a of the filter 73 and flows out from the inside of the filter 73 to the outside. At that time, the foreign matter mixed in the molten plastic is caught in the hole 73a of the filter 73, stays inside the filter 73, and is removed from the plastic to be injection molded.

  The molten plastic that has passed through the filter 73 flows into the nozzle head 69 through the outer peripheral path 71 a of the second cap 71. The molten plastic that has flowed into the nozzle head 69 passes through the nozzle path 69 a and is pressed into the mold 66. Thereby, parts, such as the front cover 17, the rear cover 18, the main body base 14, and the winding knob 11, are newly formed.

  If the filter 73 of the nozzle 65 becomes clogged and the pressure loss increases, the cleaning nozzle 75a of the cleaning plunger 75 is inserted into the nozzle path 69a of the nozzle head 69 as shown in FIG. 75 is pressed against the mold 66. The cleaning nozzle 75a presses the conversion shaft 72 at its tip and slides it toward the molding machine main body.

  The first connection path 72 a is connected to the outer peripheral path 70 b of the first cap 70 by sliding the conversion shaft 72 toward the molding machine main body. Thereafter, when molten plastic is poured from the injection molding machine 64, the molten plastic flows outside the filter 73 through the outer peripheral path 70 b of the first cap 70. And it flows into the inside of the filter 73, eliminating the clogging of the hole 73a of the filter 73. The molten plastic that has flowed into the filter 73 passes through the second connection path 72b at the tip of the conversion shaft 72, flows into the cleaning nozzle 75a of the cleaning plunger 75, and is discharged from the discharge port 75b.

  As described above, by not performing the pelletizing process, the energy consumption can be reduced to about 40% of the recycling method in the case of the pelletizing process and to about 10% in the case of the virgin plastic, thereby greatly reducing the cost. be able to. In addition, since organic solvents, detergents, and chlorofluorocarbons are not used for cleaning, the environmental load and wastewater treatment costs can be greatly reduced.

  In order to perform stable molding from the crushed plastic, the size of the crushed plastic is important. If the size of the crushed plastic is too large or too small, the following problems occur.

・ Problems that occur when the size of crushed plastic is too large.
(1) It is likely to be clogged in each part such as the inside of the cleaning machine and conveyance.
Since the crushed plastic is indefinite, when it is pressed densely, it is easy to block, and it becomes a lump and easily clogs.
(2) The filling efficiency in the molding machine is deteriorated.
Since there is more wasted space between the crushed plastics, the amount of plastic that can be filled into the molding machine is reduced.
(3) Dehydration is worse.
Since the blind hole and the part of the bag shape of the plastic product remain without being crushed, it becomes difficult to remove the cleaning liquid and the foreign matter.
・ Problems that occur when the size of crushed plastic is too small.
(1) There are many plastic losses.
Since the proportion of powdered plastic increases, the amount removed in the washing machine increases.
(2) Molding tends to be unstable.
The size of the crushed plastic increases, and the formability tends to become unstable due to, for example, inconsistency in the melting rate during molding.
(3) It is easy to stay by air conveyance.
The smaller the size, the worse the efficiency of air conveyance, and the more likely it is to stay in the piping.

  There is a pellet size (φ2 mm × 3 mm) as a size that has a proven track record in stable molding, and if the size of the crushed plastic is close to that of the pellet, a stable molding can be achieved as well. In order to define the size of the crushed plastic, the hole diameter of the screen through which the crushed plastic passes, used in the fine crusher, may be set appropriately. In order to check the size of the crushed plastic obtained according to the hole diameter of the screen, prepare screens with holes of φ5mm, φ6mm, and φ7mm, set them in a fine crusher, and actually crush the film unit with lens. It was. The result is shown in the graph of FIG.

  FIG. 12 is a graph showing the relationship between the hole diameter of the screen and the particle size distribution of the crushed plastic. As can be seen from this graph, in the screen having a hole diameter of 5 mm, the amount of crushed plastic with a side of 2 mm or less is large, and in particular, the amount of crushed plastic with a side of 1 mm or less that is a loss during cleaning increases. Further, in a screen having a hole diameter of φ7 mm, the number of crushed plastics with a side of 5 mm or more increases, and the frequency of occurrence of the above-described problems increases. Compared with these, it was found that a screen having a hole diameter of φ6 mm can obtain a lot of crushed plastic having a size of about 2 to 4 mm on one side close to the pellet, and is most suitable for pelletizing-less molding.

  Next, using the crushed plastic obtained with a crusher using a screen with a hole diameter of φ6 mm, the components of the film unit with lens, for example, the base of the main body are actually molded, and the weight variation is measured and molded. The stability was evaluated. The result is shown in the graph of FIG. In addition, as a comparative example, the weight fluctuation at the time of shape | molding a main body base using a reproduction | regeneration pellet is also written together.

  FIG. 13 shows the weight of a molded product with a predetermined number of shots when a main body base, which is a component part of a lens-fitted photo film unit, is molded by 15000 shots. As shown in this graph, the body base molded with crushed plastic can stably mold a molded product with a weight near the middle between the upper and lower limits, compared with the case of using recycled pellets. However, it was found that it is possible to obtain a molded product that is in no way inferior.

In addition, the cleanliness of the plastic when the crushed plastic is actually washed with the washing machine will be described below. Various specifications of the used washer and the kind of the washed plastic are as described below.
Specifications of cleaning machine Cleaning tank diameter Dt: φ800mm
Inclination angle θ at the bottom of the cleaning tank: 35 degrees Punch plate dimensions: Circumference length Pl600mm, Height Ph400mm
Hole diameter of punch plate: φ1mm
Punch plate opening ratio: about 14%
Suction port and circulating pipe diameter Di: 40 mm
Pump pressure: 3.6 Kg / cm ²
Pump discharge rate: 350 liters / minute Circulation frequency: 20 times / minute Cleaning fluid: Hot water (60 ° C)
Object to be cleaned Type: PS resin already kneaded with carbon Specific gravity: 1.05
Washing amount: 20kg
Adhering dirt: sebum

  FIG. 14 is a graph showing the relationship between the cleanliness of the crushed plastic washed by the washing machine having the above performance and the washing time required for this. The cleanliness of the plastic was measured by the water drop method. In this water drop method, a certain amount of pure water is dropped on a test sample, and the diameter of the water drop generated at that time is measured. As the surface of the test sample becomes cleaner, the water droplet becomes rounder with the surface tension, and the water droplet diameter becomes smaller. On the other hand, if the surface of the test sample is dirty, the water droplet diameter increases.

  As can be seen from this graph, in the crushed plastic before washing, the diameter of the water droplet is about 2.7 mm. This is considerably larger than the water droplet diameter of 1.9 mm when the test is performed on a new front cover, for example, and it can be seen that the surface is contaminated with sebum.

  When this crushed plastic is put into a washing machine in the same manner as described above and circulated with washing water, it is cleaned to the extent that the water droplet diameter becomes 2.05 mm in 0.5 minutes. Since the used washer has a performance of 20 times / minute, a cleanliness level close to that of a new front cover can be obtained by circulation of about 10 times. Further, when the washing is performed for 3 minutes, the water droplet diameter becomes 1.75 mm, and the surface can be cleaned more than a new molded product. Thus, it can be seen that oily and fat stains that normally require organic solvents and detergents (sebum is difficult to fall off with oils and fats) can be cleaned in a short time with only warm water. The reason why the product is cleaner than a new molded product is to remove the release agent attached to the surface during molding.

  In addition, the cleaning liquid has a higher cleaning effect due to the activation effect as the temperature is higher. Therefore, the washing power was tested by changing the temperature of the washing water in the washing machine. The result is shown in the graph of FIG. The test conditions are almost the same as those of the above-described washing machine, but the attached dirt is press oil and the washing time is 3 minutes.

  As can be seen from this graph, even when the temperature of the washing water is 40 ° C., washing can be performed so as to be cleaner than a new molded product. In addition, even if the temperature of the cleaning water is 22 ° C., which is the normal temperature of tap water, it can be cleaned to a level of a new molded article by cleaning for 3 minutes. As described above, since the washing ability can be changed by changing the operation content of the washing machine, from the viewpoint of energy saving and environmental load reduction, depending on the degree of dirt and the required washing tact, etc., the washing water It is necessary to set the temperature, washing time, amount of washing water, etc.

  In place of the punch plate, a plurality of holes may be formed in the body portion 37a of the cleaning tank 37. It is also possible to substitute a wire mesh or the like. The hole diameter of the punch plate varies depending on the size of the crushed plastic to be collected. However, as the hole diameter increases, the amount removed by the filter of the hot water tank increases and the loss increases. Furthermore, crushing plastic is easily caught on the punch plate, and clogging is likely to occur. However, if cleaning water collides with the punch plate with a certain pressure to clean the hole, the self-cleaning action prevents clogging. Can do.

  In addition, although the inclination angle of the bottom of the cleaning tank is set to 35 °, it is not limited to this as long as a predetermined spiral stable flow is formed at the time of cleaning, and an arbitrary angle of 20 to 75 ° may be used. Good.

  Furthermore, although warm water is used as the cleaning liquid, a detergent or a solvent may be used. However, since a stable flow of the crushed plastic is impaired when bubbles are generated, those having less foaming are preferable.

  Furthermore, even if foreign matter-contaminated products that are water-insoluble and have an effect on photographic properties are mixed, the dispersion effect is great, so that the concentration can be kept below a certain level with no problem. Further, since the cleaning power is strong, when short time cleaning is sufficient, the cleaning can be performed while moving in the pipe, and the transfer and the cleaning can be combined.

  In the above embodiment, washing of crushed plastic has been described as an example. However, an object that is difficult to disperse by stirring because it has a low specific gravity, such as powder, and easily floats in the liquid, keeps the suction port open, Can be sent into the circulation pipe without being separated, so that it can be used for the work of efficiently dispersing, dissolving, or mixing in a liquid. In this case, the punch plate functions to properly distribute the liquid containing the powder between the liquid feed pump side and the washing tank side, and the liquid feed pump is of a type capable of feeding a slurry in which the powder is dissolved. Good.

  Further, in the above embodiment, a filter is incorporated in the nozzle of an injection molding machine that performs molding of recycled plastic, but this filter can also be used in a general injection molding machine that performs molding using virgin plastic. Troubles caused by foreign matter can be prevented.

It is an external view which shows an example of the film unit with a lens recycled using this invention. It is a disassembled perspective view which shows the structure of a unit main body. It is a block diagram which shows the structure of the recycling plant of a film unit with a lens. It is the schematic which shows the structure of a plastic parts reproduction line. It is an external appearance perspective view which shows the structure of a washing machine. It is principal part sectional drawing of a washing machine. It is a top view of a washing machine. It is principal part sectional drawing of the nozzle of the injection molding machine at the time of injection molding. It is an external appearance perspective view of the filter of a nozzle. It is principal part sectional drawing of a filter. It is principal part sectional drawing of the nozzle of the injection molding machine at the time of washing | cleaning. It is a graph showing the relationship between a screen diameter and the particle size distribution of a crushed plastic. It is a graph showing the weight change of a molded article. It is a graph showing the relationship between cleaning time and cleanliness. It is a graph showing the relationship between washing water temperature and cleanliness.

Explanation of symbols

2 Film unit with lens 24 Rough crusher 25 Wind sorter 26 Fine crusher 27 Washer 28 Dehydrator 29 Dryer 30 Metal detector 31 Accumulator 64 Injection molding machine 65 Nozzle 66 Mold 73 Filter 75 Washing plunger

Claims (7)

  A method for cleaning crushing plastic, characterized in that the crushing plastic obtained by crushing a used plastic product is recirculated a plurality of times together with the cleaning liquid, and the cleaning liquid and crushing plastic are spirally swirled in the middle of the recirculation.   2. The method for cleaning crushing plastic according to claim 1, wherein bubbles are generated in the cleaning liquid in the middle of recirculation between the cleaning liquid and crushing plastic. A washing tank in which a crushing plastic obtained by crushing a used plastic product and a washing liquid is provided, and a bottom portion having a substantially conical shape is continuously provided below a substantially cylindrical body.
A suction port provided at the bottom of the cleaning tank and into which cleaning liquid and crushed plastic flow;
An inflow port on one end side is connected to the suction port, and a circulation pipe arranged so that a discharge port on the other end side is along the inner surface of the cleaning tank;
An apparatus for cleaning crushing plastic, comprising: a liquid feed pump for flowing the cleaning liquid and crushing plastic flowing into the suction port into a circulation pipe and discharging the liquid from the discharge port.   4. A plurality of openings are provided in a part of a substantially cylindrical body portion of the cleaning tank to allow only a crushed plastic having a size equal to or smaller than a specified size to pass through and be removed from the cleaning tank. Crushing plastic cleaning equipment.   4. An air supply port for introducing bubbles into the cleaning liquid between the liquid supply pump and the inlet of the circulation pipe, and supplying the cleaning liquid containing bubbles to the inlet of the circulation pipe. Or the crushing plastics washing apparatus of 4.   6. The crushing plastic cleaning apparatus according to claim 3, wherein warm water is used as the cleaning liquid.   7. The apparatus for cleaning crushing plastic according to claim 3, wherein the crushing plastic is obtained by crushing a plastic molded part of a lens-fitted photo film unit.

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