JP2008080634A - High-density molding method of waste plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-density molding method of waste plastic capable of stabilizing an apparent density and suppressing molding defect due to fusion of molded products to each other even when waste plastic having different constituents is used. <P>SOLUTION: In the manufacturing method of a molded product, a lot composed of a plurality of packages of the waste plastic having a thermoplastic resin containing polyethylene and polypropylene is supplied to a molding device 10 as a plastic for molding. The lot has a plurality of kinds and the content of the thermoplastic resin in the waste plastic for each lot is different. The content of the thermoplastic resin in the waste plastic is previously measured for each lot. Two or more lots are selected from the lot, and supplied in a conveying container 21 of a molding device 10 as a plastic for molding so that the content of the thermoplastic resin becomes 40 mass% or more. While exhausting the gas in the conveying container 21 to the outside, the molded product is manufactured by setting the temperature of the plastic for molding to be 180°C or more and 220°C or less in passing through the mold 23 with a heating means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for high-density molding of waste plastic that can be used, for example, in the production of coke or the raw material of a blast furnace.

Conventionally, many kinds of plastics are used for household use or industrial use, but finally, these were discarded as general waste or industrial waste (hereinafter simply referred to as waste plastic). These waste plastics include, for example, thermoplastic resins such as polystyrene resins, polyvinyl chloride resins, polyolefin resins, and polyester resins, or thermosetting resins. For this reason, when waste plastics are incinerated, contained chlorine and the like cause pollution, and therefore, it has been attempted to treat them appropriately and reuse them as resources.
For example, Patent Document 1 discloses a technique for compressing and molding a waste plastic that defines a content ratio of polyethylene and polypropylene in a temperature range of 100 to 140 ° C.
Patent Document 2 discloses a method for producing a high-density waste plastic molding having an apparent density of 0.7 to 1.2 kg / liter. In order to obtain a high-density molded product, the heating temperature of the waste plastic at the time of compression molding is over 160 ° C. and 250 ° C. or less (preferably 220 ° C. or less), and the gas generated from the waste plastic during the heating is removed by exhaust. is doing.

JP 2001-232634 A JP 2005-126486 A

However, in the method of Patent Document 1, since the temperature for molding the waste plastic is as low as 100 to 140 ° C., the apparent density of the molded product is as low as about 0.66 kg / liter. For this reason, for example, when the obtained molded product is used in a coke oven, the contact area between the molded product and coal becomes large, making it easy to produce coke with low strength and poor quality, and the volume of the coke oven is determined. Therefore, there is a problem that the amount of coke produced decreases as the proportion of the molded product increases and the productivity deteriorates.
Moreover, in patent document 1, in order to improve the moldability of a molded product, the content ratio of polyethylene and polypropylene is specified. However, because waste plastics are collected, for example, by local governments or local government associations (hereinafter also simply referred to as local governments), the amount of polyethylene and polypropylene contained in waste plastics is not constant in all municipalities. However, it may be difficult to improve the moldability of the obtained molded product.
Further, from the viewpoint of extending the life of the molding apparatus (wearing of the molding machine), the amount of the inorganic substance to be mixed is specified. However, although there is an effect, there is room for improvement in extending the life of the molding apparatus.
On the other hand, according to the method of Patent Document 2, it is possible to produce a high-density waste plastic molding. However, since waste plastics are collected by local governments, for example, the constituent composition of waste plastics is not constant throughout the local governments. For example, apparent density fluctuations or waste plastic moldability deteriorates. (If the fluctuation is significant, the waste plastic will be pulverized without being molded, or the melting will be significant and it will be impossible to cut the molded product after extrusion molding. Furthermore, the molded product will be cut to a predetermined length. Inconveniences such as mutual fusion occur).

The present invention has been made in view of such circumstances, and even if waste plastics having different constituent components are used, for example, the density of waste plastics can stabilize the apparent density and suppress molding defects due to fusion between molded products. An object is to provide a forming method.

The high-density molding method for waste plastic according to the present invention that meets the above-mentioned object is a method for molding a lot consisting of a plurality of packages in which waste plastic having a thermoplastic resin containing either 1 or 2 of polyethylene and polypropylene is packed. As a plastic, a transport container for storing the molding plastic, a heating means for heating the molding plastic in the transport container, and a screw for extruding the molding plastic heated by the heating means from the transport container to the outside And supplying to a molding apparatus having a mold provided with an opening for molding the molding plastic which is provided at the downstream end of the transport container and is extruded from the transport container, and from the opening of the mold In the molding method of waste plastics that are extruded to produce molded products,
There are a plurality of types of lots, and the content of the thermoplastic resin in the waste plastic is different for each lot, and the content of the thermoplastic resin in the waste plastic is measured in advance for each lot. Selecting two or more lots from the lot and supplying the molding plastic having a thermoplastic resin content of 40% by mass or more into the transport container of the molding apparatus, While the gas inside is exhausted to the outside, the temperature of the molding plastic when passing through the mold is set to 180 ° C. or higher and 220 ° C. or lower by the heating means to manufacture the molded product.

In the high-density molding method for waste plastic according to the present invention, each lot is collected for each group that collects the waste plastic, and the package is a product obtained by compressing and packaging the waste plastic to be discarded. It is preferable that
In the waste plastic high-density molding method according to the present invention, the fluctuation of the extrusion pressure of the molding plastic on the downstream side of the screw and the upstream side of the mold is within a range of 0.7 MPa to 1.3 MPa. Is preferred.

In the high-density molding method for waste plastic according to the present invention, it is preferable that the molding plastic is supplied to the molding apparatus after the package of the selected lot is mixed in advance by a mixing apparatus.
In the waste plastic high-density molding method according to the present invention, the molding plastic is supplied to the molding apparatus by mixing the package of the selected lot with a conveying means that supplies the molding apparatus (for example, alternately). It is preferable to carry out mounting.

The high density molding method of waste plastics according to claims 1 to 5, wherein two or more lots are selected from a plurality of lots having different thermoplastic resin contents, and the thermoplastic resin content is 40% by mass or more. Since molded products are manufactured with molding plastics, it is possible to use lots of types that could not be used in the past to manufacture high-density molded products. Can also be expanded.
In addition, the molding plastic with a thermoplastic resin content of 40% by mass or more is supplied to a molding apparatus and heated to 180 ° C. or higher and 220 ° C. or lower so that the thermoplastic resin is easily melted. The moldability of the molded product can be improved.
Thereby, for example, a high-density molded product can be stably supplied to a coke factory. In addition, since a high-density molded product can be used stably, it has little influence on coke strength, can produce coke with good quality with high productivity, and is useful for supporting blast furnace operation.

In particular, the high-density molding method for waste plastic according to claim 2 can increase the number of organizations (for example, local governments) that discharge waste plastic having a thermoplastic resin necessary for high-density molding as compared with the conventional method. The social contribution in the recycling business can be further improved than before.
The waste plastic high-density molding method according to claim 3 sets the extrusion pressure of the molding plastic. For example, excessive fusion between the molded products and foaming of the molded products are suppressed, and a high-density molded product is formed. Can be manufactured with good yield.

In the method for high-density molding of waste plastic according to claim 4, since the waste plastic in the package of the selected lot is mixed in advance before being supplied to the molding apparatus, a molded product of stable quality can be produced.
The method for high-density molding of waste plastic according to claim 5, because the package of the selected lot is mixed with the conveying means and placed and supplied to the molding device, for example, there is no need to use a dedicated mixing device, The package can be supplied to the molding apparatus as it is, and the workability is good.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of the softening temperature for each constituent component of waste plastic to which the high density molding method of waste plastic according to one embodiment of the present invention is applied, and FIG. 2 is vinyl chloride contained in the waste plastic. FIG. 3 is an explanatory view showing the amount of gas generated during dry distillation, FIG. 3 is an explanatory view showing the relationship between the amount of polyethylene and polypropylene contained in the waste plastic and the apparent density of the molding plastic, and FIGS. It is explanatory drawing of the waste plastic recycling equipment used with the high-density molding method of the waste plastic which concerns on embodiment.

As shown in FIGS. 1 to 5, the waste plastic high-density molding method according to one embodiment of the present invention is packaged with a waste plastic having a thermoplastic resin containing either 1 or 2 of polyethylene and polypropylene. In this method, a lot made of a plurality of packages is supplied as molding plastic to the molding apparatus 10 to produce a molded product. In addition, as long as the above-mentioned thermoplastic resin has a softening temperature of 180 ° C. or less, it is not necessary to constitute all of it with either 1 or 2 of polyethylene and polypropylene (in this case, 100 mass of the thermoplastic resin). %, Any one or two of polyethylene and polypropylene contained therein may be 70% by mass or more, or any one or two of polyethylene and polypropylene may constitute the whole (100% by mass). This will be described in detail below.

For example, waste plastic discharged from a home is conveyed to a waste plastic recycling facility by a truck or the like.
Waste plastic discharged from households is generally collected for each local government or local government association (hereinafter also simply referred to as a local government), which is an example of an organization, and is transported to a waste plastic recycling facility via a transit point (for example, a storage). Is done. At this time, in order to facilitate transportation and storage of the waste plastic, the recovered waste plastic is compressed and packed into a cubic shape having a side of about 1 m, for example. This is the package.

As described above, the waste plastic recycling facility is loaded with packages from a plurality of local governments and a plurality of local government associations. The waste plastic contained in the package is greatly different in the content of the thermoplastic resin because, for example, the state of use of the plastic and the form of collection of the waste plastic are different for each municipality. However, the inventors of the present application have newly found that the content of the thermoplastic resin in the package is substantially constant in the same local government, although the content varies.
Therefore, in order to distinguish the batches having different thermoplastic resin contents, a plurality of packages having similar thermoplastic resin contents are collected as a lot. Therefore, it is preferable that a plurality of packages collected for each specific municipality or each municipality association be made into one lot.

In addition, the inventors of the present application have sought to elucidate the mechanism by which molding is not stable when molding a high-density molded article having an apparent density of 0.7 kg / liter or more from the recovered waste plastic. This unstable molding means, for example, that the waste plastics do not fuse together, and that the molding equipment is corroded by gas generated from the waste plastic, and that the operation of the molding equipment must be suspended for replacement of the molding equipment. To do.
In elucidating this mechanism, the present inventors paid attention to the cause of the generation of corrosive gas as the cause of corrosion. That is, the molding temperature of the molding plastic that can ensure the moldability in an area where the generation of corrosive gas due to the decomposition of the chlorine-containing plastic does not occur (where the equipment is not corroded and worn) is 180 ° C. By setting the amount of thermoplastic resin of either 1 or 2 of polyethylene and polypropylene that melts at that temperature to 40% by mass or more of the total amount of waste plastic, a molded product of good quality can be obtained. discovered. If the temperature during molding is 250 ° C., for example, the conveying container and the screw used in the molding apparatus are significantly corroded and worn to the extent that replacement is required in about three months. By adjusting the temperature at the time of molding within the above-described temperature range, replacement is not required over a long period (for example, a period of 6 to 18 months or even longer).

The examination results of the temperature setting described above are shown in FIGS. 1 is polyethylene, PP is polypropylene, PS is polystyrene, and PET is polyethylene terephthalate. PVC in FIGS. 1 and 2 is polyvinyl chloride.
As apparent from FIGS. 1 and 2, the upper limit of the molding temperature is set to 220 ° C. because it is a temperature at which the decomposition of vinyl chloride does not proceed remarkably. If this decomposition proceeds, corrosive gas is generated, which is not preferable.
On the other hand, the lower limit of the molding temperature is set to 180 ° C., from the viewpoint of ensuring moldability, the temperature required for the polyethylene and polypropylene in the molding plastic to completely melt and to enclose other insoluble components. caused by. On the other hand, when the molding temperature is less than 180 ° C., the polypropylene is poorly melted, and the apparent density of the molding plastic cannot be increased to a higher density of 0.85 kg / liter or more.
From the above, the heating temperature of the molding plastic was set to 180 ° C. or higher and 220 ° C. or lower, but desirably the lower limit was 190 ° C. and the upper limit was 200 ° C.

In addition, as apparent from FIG. 3, by making the total amount of polyethylene and polypropylene (thermoplastic resin) in all waste plastics 40% by mass or more, the apparent density of the molding plastic is 0.85 kg / liter or more. Can be improved. In FIG. 3, when the total amount of the thermoplastic resin in the total waste plastic is 40% by mass, the polyethylene content is about 24% by mass and the polypropylene content is about 16% by mass.
In addition, although the upper limit of the content of the thermoplastic resin in the total waste plastic is not stipulated, considering the actual constituent components of the waste plastic discharged from each local government, for example, 60% by mass, and further 70 It is about mass%.
In addition, considering the actual components of waste plastic discharged from each municipality, the amount of polyethylene contained in the waste plastic is, for example, about 15% by mass to 35% by mass, and the amount of polypropylene is, for example, It is about 10 mass% or more and 25 mass% or less.

However, as a result of the survey, it was found that the number of municipalities in which the total amount of polyethylene and polypropylene in waste plastic exceeds 40% by mass is part of local governments (about 30%) and the rest is less than 40% by mass. .
Therefore, we focused on mixing waste plastics from municipalities with high and low polyethylene and polypropylene contents, and as a result, we came to the idea that waste plastics emitted by 70% of local governments can be molded at high density. That is, the proportion of each component of waste plastic collected in each local government is investigated in advance, and the proportion of the component suitable for high-density molding (either 1 or 2 of polyethylene and polypropylene is 40% by mass or more) in advance. By blending and adjusting, the range of local governments capable of high-density molding can be expanded, and high-density molding machines, that is, the molding apparatus 10 can be maintained at a high level and stable operation.

Therefore, two or more types of lots are selected from the lots collected for each local government so that the thermoplastic resin content is 40% by mass or more. This selection is performed by previously measuring the content of the thermoplastic resin in the waste plastic for each lot by an extraction method using a solvent.
In the present embodiment, the measurement is performed in accordance with, for example, the method described in JP-A-9-24293. More specifically, the following procedure is used.
First, the package is crushed so as to pass through a 30 mm square sieve, and several kg of a measurement sample is collected from the crushed material and is reduced to about 100 g. Next, this reduced product is crushed to a particle size of 3 mm or less, dried at 105 ° C. for 4 hours, and further reduced to about 20 g. The reduced product is frozen and pulverized to 500 μm, then vacuum dried at 70 ° C. for 5 hours, and further reduced to 1 g. What was reduced in this way was measured by the method described in JP-A-9-24293, paragraphs 0007 to 0015.

Here, Table 1 shows the result of measuring the constituent components of the waste plastic contained in the lot collected for each municipality. In Table 1, PS is polystyrene, PVC is polyvinyl chloride, PVDC is polyvinylidene chloride, PE is polyethylene, PP is polypropylene, and PET is polyethylene terephthalate. The low molecular weight compounds in Table 1 are presumed to be low molecular weight organic compounds such as resin additives (antioxidants, plasticizers, etc.). The insoluble matter is estimated to be paper, wood, resin (thermosetting resin), inorganic filler, etc. insoluble in the organic solvent used in the solvent fractionation. The total value of each component described in Table 1 has an error of ± 0.1% by mass with respect to 100% by mass, but this is an error when rounding the numerical value of each component and is problematic Absent.

From Table 1, lots collected by each municipality are of different types, and the content of the thermoplastic resin in the waste plastic varies from lot to lot, and the municipalities are characterized by the contents of polyethylene and polypropylene. I understand. This is due to, for example, differences in the usage status of plastics in local governments, the waste plastic collection rules for each local government, and the processing methods for the collected waste plastic in local governments.
For this reason, it was found that the content of polyethylene and polypropylene in each municipality was generally stable for each municipality.

From the above results, two or more types of lots selected so that the content of the thermoplastic resin is 40% by mass or more are pre-processed as molding plastics with various apparatuses shown in FIG. To the molding apparatus 10 shown in FIG.
Here, when adjusting the content of the thermoplastic resin, as shown in Table 1, the ratio of the constituent components of the waste plastic of each local government lot is measured, and a database is prepared as information used in the adjustment. Good. The measurement of the content of the thermoplastic resin may be performed every time each lot arrives. However, when the content is stable, it is not necessary to measure the content every time it is received.
And we will operate while considering the combination in the current stock situation so that the raw material conditions are suitable for high density molding. The conditions are preferably such that the content of the thermoplastic resin containing either 1 or 2 of polyethylene and polypropylene is 40% by mass or more, and the insoluble content is 15% by mass or less.

When the combination of lots is determined in this way, as shown in FIG. 4, the package of the selected lot is sequentially placed on a supply conveyor (an example of a conveying means) (not shown) by, for example, a forklift 11, It puts into the unpacking bag breaking machine 12 arrange | positioned in the downstream of a supply conveyor. As a result, the vinyl wrapped around the waste plastic is peeled off, and the waste plastic inside the package comes out.
The waste plastic unpacked in this way is conveyed downstream by the belt conveyor 13. At this time, for example, garbage (for example, wood, paper, or metal) that can be clearly confirmed by visual inspection is manually passed. Removed (hand sorting).

The waste plastic from which the dust has been removed is crushed by the coarse crusher 14 (for example, about 150 mm or less), and further subjected to wind sorting through a plurality of machine sorters 15 and 16 (for example, wind sorting or magnetic sorting). Unnecessary substances are removed by the PVC removing device 17 used. Then, the waste plastic from which unnecessary materials have been removed is further crushed (for example, about 30 mm or less) by the secondary crusher 18, and then supplied to the molding apparatus 10 shown in FIG.
In addition, when mounting the package of each lot on a supply conveyor, it is preferable to mix and mount the package of a different kind of lot so that the quantity of thermoplastic resin may satisfy 40 mass% or more. As a result, the molding plastic supplied to the molding apparatus 10 is subjected to a crushing process by the coarse crusher 14 and the secondary crusher 18 and a sorting process by the machine sorters 15 and 16, and therefore a dedicated mixing device is used. There is no need.

Here, the specific example in the case of mixing a package and mounting in a supply conveyor is demonstrated.
For example, in the case of lot A containing 50% by mass of polyethylene and polypropylene (hereinafter referred to as thermoplastic resin) and lot B containing 30% by mass, lot A and lot B should be mixed in a ratio of 1: 1. Thus, the amount of the thermoplastic resin becomes 40% by mass, and therefore, the packages a and b constituting each lot are in the order of a, b, a, b, a, b, a, b, a, b. Place alternately on the supply conveyor.
In addition, when mixing lot C having a small thermoplastic resin content and lot D having a large thermoplastic resin content in a ratio of 3 to 7 so that the amount of the thermoplastic resin is 40% by mass, The ratio of the mixture of lot C and lot D in the input process (each part), such as c, d, d, c, d, d, c, d, d, d, is a preset ratio (here, 3 to 7). ), The packages c and d constituting each lot are mixed and placed on the supply conveyor.

As described above, when placing the package of each lot on the supply conveyor, it is preferable for mixing to be placed on the supply conveyor, but it is preferable for each lot without mixing and placing the package on the supply conveyor. Preprocessing can also be performed by the various devices described above.
In this case, waste plastic for each lot that has been crushed by the secondary crusher 18 is supplied to the mixing device 19 shown in FIG. 5 so that the amount of the thermoplastic resin satisfies 40% by mass or more, and mixed in advance. After that, it can be supplied to the molding apparatus 10 via the conveyor 20.

A molding apparatus 10 that manufactures a molded product includes a transport container 21 that is hollow in a rectangular shape with a long cross section in the transport direction in which the molding plastic is placed, and the molding plastic in the transport container 21 that is disposed inside the transport container 21. It has a screw (not shown) that pushes out from the transfer container 21 to the outside. In addition, this screw can use what was provided with the blade | wings helically around the rotating shaft, for example, and although two screws are arrange | positioned in parallel with the clearance gap, it may be one. .
A compactor 22 is provided in the upper part on the upstream side of the transport container 21 to send out the molding plastic into the transport container 21 while compressing it.
Further, the transport container 21 is provided with a heater (not shown) which is an example of a heating means for heating the molding plastic in the transport container 21 and is sent from the upstream side to the downstream side of the transport container 21 by a screw. The molding plastic in the transport container 21 can be heated.

The downstream end of the transport container 21 is provided with a mold 23 having an opening having a circular cross section (or a rectangle), and the molding plastic heated by the heater is used as the opening of the mold 23. It is formed in the shape of a bar that is extruded from the inside of the transport container 21 to the outside.
A plurality of (or one) vents 24 and 25 for exhausting gas (for example, water vapor) in the transport container 21 to the outside are provided in the middle of the transport container 21 in the longitudinal direction.
Thus, the molding plastic is supplied into the transport container 21 through the compactor 22 of the molding apparatus 10, and the gas in the transport container 21 is exhausted to the outside through the vents 24 and 25 while passing through the mold 23 by the heater. The temperature of the molding plastic at that time is set to 180 ° C. or higher and 220 ° C. or lower to produce a molded product.

By the above method, fusion between waste plastics can be promoted and a high-density molded product can be produced. For example, there is a problem that the fusion between molded products becomes excessive or the molded product foams. Newly occurs.
The fusion between the molded products is a phenomenon that occurs when the melt is excessively present, and the extrusion pressure of the molding plastic is lowered. In addition, in the knowledge of the present inventors, when the extrusion pressure is a numerical value lower than −30% of the set pressure (the set pressure of the molding apparatus 10 used in the present embodiment is 1 MPa, and therefore 0.7 MPa), Although it was possible to produce a molded product, it was found that fusion was remarkable and the yield of the molded product was reduced.

On the other hand, foaming of the molded product causes remarkable foaming of the gas in the molten waste plastic due to the pressure difference when extrusion molding is performed from the inside of the high-pressure transport container 21 where the extrusion pressure is applied to the atmosphere where the pressure decreases. Caused by This phenomenon may occur when the pressure difference between before and after extrusion is large, although there is a certain suppression effect by discharging the generated gas in the transport container 21 through the vents 24 and 25.
Thus, when foaming occurs, the generation of cavities inside the molded product becomes significant, and the proportion of molded products having a density lower than the required density increases.
The inventors' knowledge has shown that foaming can be suppressed when the extrusion pressure is + 30% or less of the set pressure, that is, 1.3 MPa or less.

As shown above, pressure control is effective. This pressure control is possible, for example, by performing one or more of (1) to (4) shown below.
(1) Adjustment of charging amount (ton) per unit time of molding plastic charged into the transfer container (2) Adjustment of screw rotation speed (conveying speed of molding plastic) (3) Adjustment of heater temperature ( 4) Adjustment of the percentage of packing materials in municipalities with high content of hard-to-melt plastic contained in waste plastic Here, when increasing pressure, (1) increase in charge, (2) rotation speed What is necessary is just to take the operation action of a reduction | decrease, (3) fall of temperature, and (4) increase of the package rate of a hard-to-melt local government.
On the other hand, when lowering the pressure, (1) reduction of charge, (2) increase in rotation speed, (3) increase in temperature, and (4) decrease in the percentage of poorly fusible local government packages. Take action.

Next, examples carried out for confirming the effects of the present invention will be described.
Fig. 6 shows the evaluation of the package for each municipality that arrived in FY2005. 6 shows that the amount of the thermoplastic resin contained in the package is 40% by mass or more, and A is a municipality that can be densified as it is, and the amount of the thermoplastic resin is less than 40% by mass as it is. Although the density cannot be increased, the municipality that can be treated by mixing with A is designated as B, and the municipality that cannot be treated even when mixed with A is designated as C (total amount of plastic waste: 42,000 tons).

As is clear from FIG. 6, in the 2005 results, 31% of the local government (A) packages among all the local governments in stock were able to increase the density independently. In addition, among all the municipalities, 43% of the municipality (B) packages could not be densified as they were, but by being mixed with 31% of the municipalities (A), the densification processing became possible.
Thus, in the past, only about 30% of the local government packages received could be densified, but by applying the present invention, about 70% of the local government packages It was confirmed that can be densified.

Next, Table 2 shows the results of studying the influence of the heating temperature of the molding plastic. In addition, what has a thermoplastic resin whose amount of polyethylene in a waste plastic is 24 mass% and whose amount of polypropylene is 16 mass% was used as a plastic for a shaping | molding. The pressure of this molding plastic was adjusted so that the pressure sensor disposed near the upstream side of the mold on the downstream side of the screw would be 1 MPa. In Table 2, the temperature of the molding plastic before the mold is a temperature measured by a temperature sensor disposed in the vicinity of the upstream side of the mold, and this temperature passes through the mold by the molding plastic. It is almost the same as the temperature at the time.

As is clear from Table 2, the apparent density of the molded product is good (0.7 kg / liter) when the temperature of the molding plastic is in the range of 180 ° C. or higher and 240 ° C. or lower, but the temperature is 230 ° C. or higher. As a result, the corrosion of the molding apparatus (particularly the transport container) became prominent.
From the above, a high-density molded article can be obtained while suppressing the corrosion of the molding apparatus in the temperature range of the molding plastic from 180 ° C. to 220 ° C. (particularly from 190 ° C. to 200 ° C.). Was confirmed.

Table 3 shows the results of studying the influence of the extrusion pressure of the plastic for molding. In addition, what has a thermoplastic resin whose amount of polyethylene in a waste plastic is 24 mass% and whose amount of polypropylene is 16 mass% was used as a plastic for a shaping | molding. Further, the temperature of the molding plastic was set to 195 ° C. when passing through the temperature sensor.

As is apparent from Table 3, when the extrusion pressure of the molding plastic was in the range of 0.7 MPa to 1.3 MPa, the apparent density of the molded product was good (0.7 kg / liter), but the extrusion pressure was 0. The apparent density of the molded product was even better in the range of 0.9 MPa to 1.1 MPa.
From the above, it was confirmed that a high-density molded product can be obtained when the extrusion pressure of the molding plastic is in the range of 0.7 MPa to 1.3 MPa (particularly 0.9 MPa to 1.1 MPa).

The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. Other embodiments and modifications conceivable within the scope of the above are also included. For example, a case where the waste plastic high-density molding method of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the present invention.

It is explanatory drawing of the softening temperature for every component of waste plastic which applies the high-density molding method of waste plastic which concerns on one embodiment of this invention. It is explanatory drawing which shows the gas generation amount at the time of the vinyl chloride dry distillation contained in the waste plastic. It is explanatory drawing which shows the relationship between the quantity of the polyethylene and polypropylene contained in a waste plastic, and the apparent density of the plastic for a shaping | molding. It is explanatory drawing of the waste plastic recycling equipment used with the high-density molding method of the waste plastic which concerns on one embodiment of this invention. It is explanatory drawing of the waste plastic recycling equipment used with the high-density molding method of the waste plastic which concerns on one embodiment of this invention. It is explanatory drawing which shows the quantity of the waste plastic which can apply the high-density molding method of the waste plastic which concerns on an Example.

Explanation of symbols

10: Molding device, 11: Forklift, 12: Unpacking bag breaker, 13: Belt conveyor, 14: Rough crusher, 15, 16: Machine sorter, 17: PVC removal device, 18: Secondary crusher, 19 : Mixing device, 20: Conveyor, 21: Transport container, 22: Compactor, 23: Mold, 24, 25: Vent

Claims (5)

A lot consisting of a plurality of packing materials in which waste plastics having a thermoplastic resin containing any one or two of polyethylene and polypropylene are packed is used as molding plastic, and a transport container for storing the molding plastic, and the transport container A heating means for heating the molding plastic, a screw for extruding the molding plastic heated by the heating means from the transport container, and a downstream end of the transport container provided from the inside of the transport container. In a molding method of waste plastic that is supplied to a molding apparatus having a mold having an opening for molding the molding plastic to be extruded, and that is extruded from the opening of the mold to produce a molded product.
There are a plurality of types of lots, and the content of the thermoplastic resin in the waste plastic is different for each lot, and the content of the thermoplastic resin in the waste plastic is measured in advance for each lot. Selecting two or more lots from the lot and supplying the molding plastic having a thermoplastic resin content of 40% by mass or more into the transport container of the molding apparatus, The waste plastic is characterized in that the molded product is produced by evacuating the gas inside and setting the temperature of the molding plastic during the passage of the mold to 180 ° C. or higher and 220 ° C. or lower by the heating means. High density molding method. 2. The high density molding method of waste plastic according to claim 1, wherein each lot is collected for each group that collects the waste plastic, and the package is the compressed waste plastic that has been discarded. A high-density molding method for waste plastics characterized by being a thing. The high density molding method of waste plastics according to any one of claims 1 and 2, wherein a fluctuation of the extrusion pressure of the molding plastic on the downstream side of the screw and the upstream side of the mold is 0.7 MPa or more. A high density molding method of waste plastic, characterized by being within a range of 3 MPa or less. The high density molding method of waste plastic according to any one of claims 1 to 3, wherein the plastic for molding is supplied to the molding apparatus by previously mixing the package of the selected lot with a mixing apparatus. A high-density molding method for waste plastic, which is performed later. The high density molding method of waste plastics according to any one of claims 1 to 3, wherein the molding plastic is supplied to the molding apparatus by supplying the package of the selected lot to the molding apparatus. A high density molding method of waste plastic, which is carried out by mixing with a conveying means.

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