Compression volume reduction processing method of foam resin waste

Abstract

To provide a method for compressing and reducing the volume of foamed resin waste, capable of reducing the volume of foamed resin waste in large quantities at low cost near the site of generation or at a waste dump, thereby reducing transportation costs and minimizing the costs of recycling waste into a final recycling form.SOLUTION: A method for compressing and reducing a volume of foamed resin waste, comprising: a screw extruder provided inside a cylindrical casing, with a screw extruder having a feed screw for feeding a material to be compressed in an axial direction; and a cylindrical body having a diameter that gradually decreases in the direction of feeding the material to be compressed (A) communicated with an outlet at the axial end of the casing; the method compresses and reduces the volume of foamed resin waste by compressive extrusion utilizing the wall resistance inside the cylindrical casing, to reduce the apparent volume to 1 / 2 to 1 / 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for compressing and reducing the volume of foamed resin waste, and more particularly to a method for compressing and reducing the volume of foamed resin waste, which is a highly expanded molded product that has a small bulk density and therefore a large volume and is therefore expensive to transport. [Background technology]

[0002] In general, foamed resin products are used as packaging materials, cushioning materials, heat insulating materials, etc. for various electrical products, various electric appliances, precision machinery products, etc. Among them, polyolefin-based resin foams are used in many areas, such as pipe covers, adhesive tapes, cushioning materials for hard disks, cushioning materials for compact disks, cushioning materials for soundproof floors, heat-insulating folded-plate roofs, etc. Meanwhile, various molded products are discarded while still containing large amounts of polyolefin-based resin, and the amount of waste is increasing year by year.

[0003] After use, foamed plastic waste is temporarily collected at industrial waste treatment plants, etc., where it is landfilled, incinerated, or reprocessed as solid fuel. However, when transported in its original state from the site where the waste was generated to a landfill treatment facility, incineration treatment facility, or solid fuel production facility, it is a waste that is difficult to handle in terms of transportation costs, as it is lightweight but has a large apparent volume. Even if it is transported, special vehicles and loading equipment are required, and the current situation is that the cost of transportation to the industrial waste treatment plant accounts for 60 to 70% of the total processing cost.

[0004] One of the means to solve this problem is to heat and melt the foamed plastic waste, then resolidify (commonly known as ingotization) to reduce the volume, but this requires an extruder equipped with a heat melting device, which is expensive and large-scale equipment, and must be installed at industrial waste disposal sites and reprocessing plants. Therefore, since such expensive equipment cannot be installed at each site where foamed plastic waste is generated, it is difficult to reduce the transportation costs to reprocessing plants, etc. In addition, when reusing the foamed plastic waste as raw fuel for furnaces that require a thermal energy source as one of the final recycling forms, re-pulverization using a large, powerful crusher is essential regardless of the combustion form, which increases costs.

[0005] Therefore, Patent Document 1 proposes a resin recycling device in which foamed resin waste is melted by compression friction heat, reduced in volume by forming it into small particles, and made compact so that it can be moved. Patent Document 2 also proposes concrete aggregate in which hydraulic powder such as cement powder is fused to the surface of small particles melted using the above-mentioned resin recycling device. However, the resin recycling device of Patent Document 1 above has extremely low processing productivity because the foamed resin waste is crushed in advance, and then melted and granulated by compression and friction heat, making it difficult to put into practical use, particularly for processing large foamed resin waste such as floats, and furthermore, because heat generation in a special rotating body friction part is utilized, the amount of heat generated is excessive, making it difficult to obtain the desired granulated product. Moreover, in the case of the concrete aggregate according to Patent Document 2, not only is the productivity low as in the above, but the granulated surface in the molten state is no longer in a foamed state and the surface irregularities disappear, so that even if the cement powder etc. is partially welded, there is no room for the cement powder etc. to penetrate into the irregularities, and it is difficult to obtain a lightweight concrete aggregate that is well bonded to the cement, etc. Therefore, there is a strong demand for a waste treatment method that can easily reduce the volume of foamed resin waste at the generation site or waste dump, etc., with high treatment productivity, and for the development of recycled products with high reusability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 54-12512 [Patent Document 2] Utility model registration No. 3068597 Summary of the Invention [Problem to be solved by the invention]

[0007] In light of the current situation, the present invention aims to provide a method for compressing and reducing the volume of foamed resin waste, which can reduce the volume of foamed resin waste in large quantities and at low cost near the site of generation or at a waste dump, thereby reducing transportation costs and minimizing the costs of recycling the waste into a final recycled use form. [Means for solving the problem]

[0008] As a result of various investigations aimed at solving the above problems, the present inventors have found that the above problems can be solved by the compressed and reduced volume material made of resin foam product waste and the processing method described below. That is, the present invention has the following configuration. (1) A screw extruder having a feed screw for feeding the material to be compressed in the axial direction is provided in a cylindrical casing, and a cylindrical body having a diameter gradually decreasing toward the feeding direction (A) of the material to be compressed is connected to the outlet of the axial end of the casing. The method for compressing and reducing the volume of foamed resin waste comprises compressing and reducing the volume of the foamed resin waste to 1 / 2 to 1 / 50 of its apparent volume by compression and extrusion utilizing the wall resistance inside the cylindrical casing. (2) A method for compressing and reducing the volume of foamed resin waste as described in (1) above, which compresses and reduces the volume of foamed resin waste generated during the production of foamed resin. (3) A method for compressing and reducing the volume of foamed resin waste as described in (2) above, in which foamed resin waste generated continuously during the production of foamed resin is continuously compressed and reduced in volume. (4) The method for compressing and reducing the volume of foamed resin waste according to any one of the above (1) to (3), wherein the foamed resin waste is foamed resin waste. Effect of the Invention

[0009] According to the present invention, foamed resin waste can be reduced in volume in large quantities at low cost near the site of generation or at a waste dump, thereby reducing transportation costs and minimizing costs for recycling into final reuse form. [Brief description of the drawings]

[0010] [Figure 1] Schematic diagram of the compression and volume reduction device DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail.

[0012] The method for compressing and reducing the volume of foamed resin waste of the present invention comprises providing a screw extruder equipped with a feed screw for feeding the material to be compressed in the axial direction inside a cylindrical casing, and using a device having a structure in which a cylindrical body whose diameter gradually decreases toward the direction in which the material to be compressed is fed (A) connected to an outlet portion at the axial end of the casing, the foamed resin waste is compressed and reduced in volume to 1 / 2 to 1 / 50 of its apparent volume by compression extrusion utilizing the wall resistance inside the cylindrical casing.

[0013] Examples of foamed resin waste handled in the present invention include packaging materials, cushioning materials, and heat insulating materials for various electrical appliances and precision machinery products. Specific examples include pipe covers, adhesive tapes, hard disk cushioning materials, compact disk cushioning materials, soundproof floor cushioning materials, and heat-insulating folded-plate roofing materials, all of which can be treated as target products. Foamed resin waste may have skins or tapes attached in addition to the foam. In particular, it is preferable that the foamed resin composition and the skins or tapes are the same type of resin composition in consideration of recyclability.

[0014] In addition, the present invention can be used to compress and reduce the volume of foamed resin waste generated during the production of foamed resin. In general, in the production of foamed resin, the foamed resin is cut to a predetermined width and the ends are cut off, and the unnecessary ends can be compressed and reduced in volume.

[0015] The foam is produced by mixing a foaming agent capable of generating gas into a resin mixture, and the production methods include the atmospheric foaming method in which a thermally decomposed chemical foaming agent is added as a foaming agent to the resin mixture, melt-kneaded, and foamed by heating at atmospheric pressure, the extrusion foaming method in which a thermally decomposed chemical foaming agent is thermally decomposed in an extruder and foamed while being extruded under high pressure, the press foaming method in which a thermally decomposed chemical foaming agent is thermally decomposed in a press die and foamed while being reduced pressure, and the extrusion foaming method in which a gas or a vaporizing solvent is melt-mixed in an extruder and foamed while being extruded under high pressure. An example of the atmospheric foaming method is a method in which a thermally decomposed chemical foaming agent is added as a foaming agent to a resin mixture in an extruder, melt-kneaded, and then a foam sheet is heated and foamed, and then the foam is continuously foamed in a vertical or horizontal hot air foaming furnace, a chemical bath such as molten salt, etc.

[0016] When the compressive volume reduction treatment is carried out continuously, it is preferable that the compression treatment speed of the reduced volume material can be 1 to 30 m / min, taking into consideration the speed of the foaming step in which foaming is carried out continuously.

[0017] The foamed resin waste to be subjected to the compression volume reduction treatment can be used in various resin compositions. For example, polyurethane resin, polystyrene resin, polyimide resin, vinyl chloride resin, polyolefin resin composition, etc. can be mentioned. It is particularly suitable for use in polyolefin resin compositions.

[0018] The polyolefin resin composition is not particularly limited, but examples thereof include polyethylene resins such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and very low-density polyethylene (density is defined as follows: very low density: less than 910 kg / m3, low density: 910 kg / m3 or more and 940 kg / m3 or less, high density: 940 kg / m3 or more and 965 kg / m3 or less), copolymers mainly composed of ethylene, or polypropylene resins such as homopolypropylene, ethylene-propylene random copolymer, and ethylene-propylene block copolymer, and mixtures thereof may be used.

[0019] In addition, when a polyethylene resin is used as the polyolefin resin, an ethylene copolymer can be used in addition to homopolyethylene. The ethylene copolymer refers to a copolymer or multicomponent copolymer of ethylene and another monomer. Examples of the ethylene copolymer include an ethylene-α-olefin copolymer obtained by polymerizing ethylene and an α-olefin having 4 or more carbon atoms (e.g., 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, etc.), an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, etc.

[0020] For the polyolefin-based resin foam sheet of the present invention, either a crosslinked resin foam (hereinafter referred to as a crosslinked foam) or a non-crosslinked resin foam (hereinafter referred to as a non-crosslinked foam) can be used, and an appropriate resin foam can be selected depending on the application.

[0021] The location for treating foamed resin waste is preferably near the site where it is generated in order to reduce transportation costs, but it may also be a waste dump such as a nearby industrial waste disposal site. The foamed resin waste volume reduction device used in the present invention is an extruder equipped with a crushing means consisting of multiple crushing rotary blades on a rotating shaft extending into the bottom, a transporting means consisting of a spiral screw, and a cylindrical extrusion port located approximately on the same line at the tip of the extruder, and has a simple structure that is compact and movable because no heating means is required. An example of this device will be described in detail with reference to the attached Figure 1.

[0022] FIG. 1 is a conceptual diagram of the device configuration for carrying out the present invention. The inlet 1 is the inlet for the foamed resin waste of the volume reduction device. There are no restrictions on the shape of the inlet, but it is preferable that the area of ​​the inlet is 1.5 times or more larger than the waste to be fed, so that the waste can be fed smoothly through the opening. In addition, when the foamed resin waste is foamed resin waste that is continuously generated during the production of foamed resin, it is necessary to continuously feed the sheet-like foam from the inlet, and a guide or the like may be attached to facilitate continuous feeding.

[0023] The receiving section 2 is a receiving section that transports the foamed resin waste into the device. There are no particular restrictions on the method of receiving, but a nip roll may be used. Also, if the shape of the foamed resin waste is sufficiently small for the input port or the entrance of the cutting section 3 described later, and it falls into the cutting section under its own weight, a receiving device may not be used.

[0024] The cutting section 3 is configured so that foamed plastic waste fed from the feed port side falls and is fed to the cutting device in the cutting section. There are no particular restrictions on the cutting method of the cutting device, but it is preferable that a rotary cutter rotated by a rotating shaft is provided and the waste is cut by the cutter. The foamed plastic waste fed from above is cut here, and the resulting cutting chips fall downward. The cutting section is configured with upper and lower openings, but the lower opening allows the cutting chips cut by the cutting device to fall and be discharged downward.

[0025] The foamed resin waste cut in the cutting section 3 passes through the compressed object passing section 4 and is transported to the compression section 6 by the transport device of the transport section 5.

[0026] There are no particular restrictions on the conveying device used in the conveying section 5, but it is preferable to convey the material to be compressed by a screw extruder equipped with a feed screw that feeds the material in the axial direction. In more detail, the screw extruder is configured such that a feed screw is supported in a cylindrical casing so as to be rotatable about its axis, and a driving means (such as a geared motor) is provided on the rear end side of the casing. The casing is formed in a cylindrical shape, and is placed on the floor and fixed to a stand 8 so that it is inclined upward toward the front. The cut scraps supplied into the casing by this feed screw are conveyed toward the compression section 6.

[0027] In the compression section 6, the material to be compressed is compressed by connecting a cylindrical body whose diameter gradually decreases toward the discharge port 7, and the cutting scraps are compressed by utilizing the wall resistance of the tube. Here, the cutting scraps are discharged from the discharge port 7 while being compressed and reduced in apparent volume to 1 / 2 to 1 / 50, preferably 1 / 5 to 1 / 30, of the foamed resin waste. If the apparent volume of the obtained compressed and reduced material is larger than 1 / 2 of the foamed resin waste, it is not desirable because it is hardly compressed and reduced in volume, and transportation costs cannot be reduced. On the other hand, if the apparent volume is smaller than 1 / 50, the surface of the compressed and reduced material to be extruded melts and resolidifies due to excessive frictional heat caused by the wall resistance, and if it is to be reused, it is not desirable because secondary pulverization is required. In order to adjust the compression reduction rate to a desired value, adjustment means such as increasing or decreasing the amount of waste to be processed, the conveying speed, or the cross-sectional area of ​​the cylindrical extrusion port can be used. In particular, as an adjustment means for increasing or decreasing the cross-sectional area of ​​the cylindrical extrusion port, in addition to replacing the nozzle of the cylindrical extrusion port, it is preferable to divide the cylindrical extrusion port itself in the extrusion direction (preferably into two parts) without replacing the nozzle, and adjust the width of the gap at the dividing line as necessary with an adjustment means such as a bolt. Although such a volume reduction device is not equipped with a heating and melting device, it is preferable to appropriately equip it with a temperature sensor and take measures to automatically stop or restart the device when the temperature rises excessively in order to prevent the surface of the compressed volume reduction product being extruded from melting and resolidifying due to frictional heat.

[0028] The volume reduction device used in the above-mentioned processing method of the present invention is inexpensive because it does not require a heating and melting device, and can be installed at many foamed resin waste generation locations because it is a simple volume reduction device with a compact configuration. Furthermore, the compressed volume reduction product of the processed foamed resin waste is compressed and reduced to a range of 1 / 2 to 1 / 50 of the foamed resin waste, and the volume does not partially increase, so that the transportation cost to a recycling plant or the like can be reduced according to the volume reduction rate.

[0029] In the present invention, the compressed waste material obtained by the above-mentioned processing method near the site of generation is transported to a recycling plant and appropriately reprocessed into a final recycling form. In particular, the compressed waste material is suitable for reuse as fuel for combustion furnaces that require a thermal energy source, such as cement kilns and combustion furnaces for waste treatment, in its original form without secondary crushing, since it has not been melted and resolidified.

[0030] In addition, since the compressed reduced volume material is obtained without melting and resolidifying, a foamed state is maintained on the surface of each crushed particle group. Therefore, when the material is transported to a recycling processing plant, secondarily crushed, and hydraulic powder such as cement powder or gypsum powder is attached to the uneven surfaces of the secondary crushed material, the amount of adhesion increases and there is no separation of the adhesion, making it suitable for reuse as an excellent lightweight concrete aggregate. EXAMPLES

[0031] The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

[0032] Example 1 The foamed polyethylene waste (a sheet-like product with an expansion ratio of about 15 times, a thickness of 3 mm, and a width of 100 mm) that is continuously generated during production in the foaming process was continuously fed into the volume reduction device with the configuration shown in Figure 1 and compressed and reduced in volume. Specifically, the volume reduction device continuously fed the foamed polyethylene waste from an inlet 1 with an opening of 400 mm in the width direction and 200 mm in the height direction, and took it out at the same speed as the production speed of the foaming process in a take-up section 2 with a nip roll structure. After that, the waste was continuously cut into 100 mm lengths in the length direction by a rotary cutter installed in the cutting section 4. After that, it was conveyed to the compression section 5 by a screw extruder having a feed screw and a cylindrical casing structure that passes through 4 and sends the compressed material in the axial direction. At that time, the feed screw diameter was 380 mm, and the rotation speed was 44 rpm. Thereafter, in the compression section 5, the compressed material was passed through a cylindrical body whose diameter gradually decreased toward the discharge port 7, and the cylindrical body was narrowed so that the cross-sectional area of ​​the cross-sectional area of ​​the cylindrical body on the inlet side of the compression section was gradually decreased to 7 / 10 of the cross-sectional area ...

[0033] Example 2 Foamed polypropylene waste (a sheet-like product with an expansion ratio of about 20 times, a thickness of 2 mm, and a width of 100 mm) that is continuously generated during production in the foaming process was continuously fed into a volume reduction device having a similar configuration to that described in Example 1, and compression and volume reduction treatment was performed. As a result of the volume reduction treatment, the apparent volume was reduced to 1 / 4. As a result of the apparent volume being reduced to 1 / 4, the material partially collapsed after extrusion as in Example 1, but no increase in volume was observed when packaged in a packaging bag, and the material could be transported without any problems in a reduced state. In addition, it was confirmed that the compressed and reduced material could be easily separated into pulverized particle groups by simple stirring and impact, and therefore could be suitably treated as a raw fuel without secondary pulverization. [Industrial Applicability]

[0034] According to the method of the present invention described above, an inexpensive, compact, simple volume reduction machine can be brought in to the site where foamed resin waste is generated or at a waste dump, etc., and the volume reduction process can be carried out. This not only reduces the subsequent transportation costs to a reuse plant, etc., but also minimizes the cost of recycling the waste into its final recycling form, making this an extremely significant invention as a method of treating industrial waste. [Explanation of symbols]

[0035] 1 Inlet 2. Collection Section 3 Cutting section 4. Compressed object passage area 5. Conveyor 6 Compression section 7 Outlet A: Compressed object feed direction

Claims

1. A screw extruder having a feed screw for feeding a material to be compressed in an axial direction is provided in a cylindrical casing, and a cylindrical body whose diameter gradually decreases in the direction of feeding the material to be compressed (A) is connected to an outlet portion at the axial end of the casing. A method for compressing and reducing the volume of foamed resin waste, comprising compressing and extruding the foamed resin waste by utilizing wall resistance within the cylindrical casing so that the apparent volume is reduced to 1 / 2 to 1 / 50, A method for compressing and reducing the volume of foamed resin waste, which compresses and reduces the volume of foamed resin waste generated during the production of foamed resin.

2. 2. The method for compressing and reducing the volume of foamed resin waste according to claim 1, wherein foamed resin waste generated continuously during the production of foamed resin is continuously compressed and reduced in volume.

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