JP7325877B1 - De-inking method - Google Patents

Abstract

Kind Code: A1 In order to peel off a paint or the like from a waste plastic, it is necessary to immerse it in alkaline water for a long time (several tens of minutes), and a large amount of alkaline water is required. To remove paint or the like in a short time (several minutes) without immersing waste plastics in alkaline water for a long time and with less alkaline water than in the prior art. A container (11) for containing a plastic piece (P) with paint or the like and alkaline water; a lid (12); a stirring mechanism (13) for stirring the plastic piece (P) and the alkaline water; A discharge mechanism 16 for discharging from the container is provided, and the alkaline water is poured into the container to the extent that the plastic pieces are just submerged without floating, and the plastic pieces are deinked and polished by stirring and polishing. ink method. [Selection drawing] Fig. 1

Description

The present invention relates to a plastic recycling method . More specifically, the present invention relates to a deinking method for peeling off paint or the like from used waste plastics.

Plastics are used in a variety of applications, from thin and light items such as films wrapped around PET bottles and food packaging bags to hard items such as lunch boxes (hard type). These are printed with product names and the like using paint. When the plastic is recycled, if the paint remains, the color becomes cloudy, which is inconvenient because the usage after recycling is limited. Therefore, a process called deinking is performed to remove the paint from the plastic during recycling.

In Patent Document 1, "Apparatus for cleaning and removing printed surface of plastic film and method for cleaning and removing the same" discloses an apparatus for cleaning and removing printed surface of plastic film, which removes the printed surface using alkaline cleaning water. a removing device main body having a discharge port for discharging the plastic film pieces from which the printed surface has been removed at the bottom of the cylinder and an opening edge for discharging the overflowing plastic film pieces and the alkaline washing water at the top of the cylinder; Inside the cylindrical body of the removal device main body, an upper opening for introducing a piece of plastic film and alkaline cleaning water is arranged with a gap in the same axial direction, and a first opening for moving it downward while stirring it. A cylindrical throwing cylinder provided with screw fins and a piece of plastic film moved from a lower opening of the throwing cylinder arranged in the same axial direction with a gap provided in the throwing cylinder, together with alkaline cleaning water, are poured upward. The shredded plastic film pieces and the alkaline washing water are introduced from the upper opening of the injection cylinder, and the plastic film pieces are printed by stirring with the first screw fin. The surface and the alkaline cleaning water are reacted, conveyed from the lower opening of the charging tube to the bottomed tube, and the second screw fin rotates between the inner surface of the bottomed tube and the outer surface of the charging tube to mix the alkaline cleaning water. Plastic film printing, wherein plastic film pieces and alkaline cleaning water overflowing from the upper opening of the bottomed cylinder are conveyed to the removal device main body and recovered from the discharge port. A surface cleaning removal device is described.
In other words, it is necessary to immerse the plastic in alkaline water for a long time (several tens of minutes) in order to peel off the paint.

JP 2022-134153 A

In order to remove the paint and the like from the waste plastic, it has been necessary to immerse the waste plastic in alkaline water for a long time (several tens of minutes). In addition, a large amount of alkaline water is required, which is costly and time-consuming, and has a high processing load.
The present invention has been created to solve such problems. That is, the waste plastic is not soaked in alkaline water for a long period of time, and the paint or the like is removed in a short time (several minutes) and with less alkaline water than in the conventional technology.

A step of storing plastic pieces obtained by pulverizing coated plastic in a container;
pouring the alkaline water into the container to such an extent that the plastic pieces are just submerged without floating; stirring the plastic pieces and the alkaline water contained in the container; and removing the alkaline water from the container. and a step of draining water, wherein the plastic pieces are deinked by being agitated and polished.

The deinking method of the present invention has the following effects.
・Compared with the conventional technology, paint can be peeled off from the plastic in a short time (several minutes).
・Compared with the conventional technology, treatment can be performed with less alkaline water, and the supply cost and wastewater treatment cost can be reduced.
・The deinking process and the rinsing process can be processed with the same equipment by providing a drain port and a flood port.
・By polishing the surface of the plastic in addition to chemically removing paint, etc., it is possible to provide recycled plastic materials of higher quality than before.

A vertical sectional view of a deinking device. Explanatory cross-sectional view of a heating and heat-retaining facility using hot water. Explanatory cross-sectional view of a heating and thermal insulation equipment using a heating wire. FIG. 4 is a vertical cross-sectional view of the deinking device during stirring and polishing; A vertical sectional view of the deinking device when draining water. A vertical sectional view of the deinking device during rinsing. A vertical sectional view of the deinking device during discharge. Schematic diagram showing the entire recycling process. The schematic diagram showing the whole recycling process including an immersion process. The flow chart showing a series of flows of a recycling process. FIG. 4 is a flow diagram showing devices that pass through in the recycling process.

An example of implementation of the deinking method of the present invention will be described with reference to the drawings.
Here, plastic refers to a synthetic resin having plasticity.

<Overall overview>
FIG. 1 is a vertical sectional view of the deinking apparatus 1. FIG.
The deinking apparatus 1 comprises a container 11 , a lid 12 , a stirring mechanism 13 , a drainage mechanism 14 , a flood mechanism 15 and a discharge mechanism 16 .
The procedure of the deinking process is as follows. Crushed plastic pieces (plastic pieces P) and alkaline water are put into the container 11 through the opening 111, and the lid 12 is closed. The stirring mechanism 13 is operated to stir and grind the plastic pieces P and the alkaline water. The plastic piece P and the alkaline water are discharged from the container 11 by the discharge mechanism 16 .

<Heating and keeping warm function>
FIG. 2 is an explanatory cross-sectional view of a heating and thermal insulation facility using hot water.
The container 11 and lid 12 have a double structure with a space in the wall.
Heated water (hot water) or the like flows in from a first inlet 112 provided at the bottom of the container 11 , so that the inside of the double wall is filled with hot water or the like, and the container 11 is heated and kept warm. By heating and maintaining the temperature (for example, at about 80 to 90° C.), the paint stripping effect of the alkaline water is enhanced. Hot water inside the container 11 is discharged from the first outlet 113 provided at the top of the container 11 . By constantly performing inflow and outflow and circulating, the heated water or the like always warms the container 11, and the inside thereof can be kept at a constant temperature. In addition, the first inlet 112 is provided at the bottom and the first outlet 113 is provided at the top, and hot water or the like is circulated by the pressure of the inflow, so that the inside of the double wall can be filled with hot water or the like without gaps due to gravity. Hot water or the like is not limited to water as long as it can mediate heat, and may be other liquids or gases such as air or steam.

Like the container 11 , the lid 12 can also have a function of heating and keeping heat by allowing heated water or the like to flow in from the second inlet 121 and to discharge from the second outlet 122 . The second outlet 122 is provided vertically above the lid 12 when the lid 12 is closed, and by circulating the hot water or the like by the inflow pressure, the double wall can be filled with the hot water or the like without gaps due to gravity, as in the case of the container 11. can.
The lid 12 may not be provided with the heating and heat retaining mechanism, and only the container 11 may be provided with the same.

FIG. 3 is an explanatory cross-sectional view of a heating and thermal insulation facility using a heating wire.
The container 11 and the lid 12 are heated by embedding the first heating wire 114 and the second heating wire 124 in the wall instead of (or in addition to) filling the inside of the double wall with heated water or the like and energizing it.・It can also be kept warm. Of course, also in this case, the lid 12 may not be provided with the heating wire, and only the container 11 may be provided with the heating wire.

<De-inking process>
FIG. 4 is a vertical cross-sectional view of the deinking device during stirring and polishing.
Alkaline water should be poured to such an extent that the plastic piece P that has been put in does not float and is just submerged. This is for the purpose of effectively polishing the plastic pieces P without creating a gap between them. In the figure, the plastic piece P is drawn as a circle, but in reality it is crushed waste plastic, and pieces of various shapes such as rectangles are mixed.

The stirring mechanism 13 is composed of a rotary shaft 131 , first blades 132 and second blades 133 . The rotary shaft 131 is rotated at an arbitrary speed by power (for example, a motor) to rotate the first blade 132 and the second blade 133 fixed to the rotary shaft 131 (for example, 300 to 2,000 rpm). As the first blade 132 and the second blade 133 rotate, a water flow is generated to three-dimensionally agitate the plastic pieces P and the alkaline water in the container 11 in the vertical and horizontal directions. The paint or the like that floats from the surface of the plastic due to the alkaline water is peeled off by rubbing the plastic pieces P against each other due to the agitation.

The bottom of container 11 is desirably curved. This is to eliminate corners and prevent stagnation during stirring. Also, the first blade 132 may be curved in accordance with the shape of the bottom.

In addition, the stirring mechanism 13 is not limited to the structure described above, and may have a structure having only one blade without the first blade 132 or the second blade 133, or may have three or more blades. Also, the number of blades may be two, or three or more.

<Vent>
Lid 12 may be provided with a vent 123 . This is for adjusting the pressure inside and outside the container 11 by ventilating. It should be noted that the vent 123 can be provided on the side surface of the container 11 instead of the lid 12 (not shown).

<Drainage mechanism>
FIG. 5 is a vertical sectional view of the deinking device during draining.
The drainage mechanism 14 comprises a drainage cutoff wall 141 , a drainage rod 142 , a drainage handle 143 , a drainage port 144 and a drainage network 145 . The drainage stop wall 141 is positioned at the bottom of the container 11 and contacts the inside to block alkaline water or the like except during drainage. The drainage stop wall 141 and the drainage handle 143 are connected by a drainage rod 142. By pulling the drainage handle 143, the drainage stop wall 141 moves from the position shown in FIG. 4 to the position shown in FIG. is discharged from the drain port 144 . At this time, the stirring mechanism 13 is preferably rotated at a low speed (for example, 500 rpm or less).
The plastic pieces P are blocked by the drainage net 145 during drainage. The drain net 145 is a net or punching metal having a large number of holes with a diameter of 1 to 3 mm through which the plastic piece P does not pass.
The drainage mechanism 14 is not limited to the structure described above as long as it can block the plastic piece P and drain only alkaline water or the like. For example, a structure that does not have the drain rod 142 and the drain handle 143 and is automatically moved (opened and closed) by electricity or the like may be used.

<Rinsing process>
FIG. 6 is a vertical sectional view of the deinking device during the rinsing process.
The drainage handle 143 is pushed to return the drainage water stop wall 141 from the position shown in FIG. 5 to the position shown in FIG. . The rinsing process is performed while continuing to pour rinsing water from the opening 111 and continuing to drain it from the flooding mechanism 15 as an overflow.
The lid 12 may be provided with a water supply port (not shown) for rinsing water so that the rinsing process can be performed with the lid 12 closed.

The flood mechanism 15 comprises a flood wall 151 , a flood bar 152 , a flood handle 153 , a flood port 154 and a flood net 155 .
The flood wall 151 is positioned on the side surface of the container 11 and is in contact with the inside to block alkaline water or the like except during rinsing. The flood wall 151 and the flood handle 153 are connected by a flood rod 152. By pulling the flood handle 153, the flood wall 151 moves from the position shown in FIG. 5 to the position shown in FIG. 154 is discharged. At this time, the plastic piece P is blocked by the flood net 155 .
The flood net 155 is a net or punching metal having a large number of holes with a diameter of 1 to 3 mm that do not allow the plastic pieces P to pass through, like the drain net 145 . This is to allow only rinsing water to pass through and block the plastic piece P.
The flooding mechanism 15 may be operated by air or may be electrically operated.

<Ejection mechanism>
FIG. 7 is a vertical cross-sectional view of the deinking apparatus 1 when discharging the plastic pieces P, rinsing water, etc. from the container 11. As shown in FIG.
The discharge mechanism 16 is composed of a water discharge stop wall 161 , a discharge rod 162 , a discharge handle 163 and a discharge port 164 . The discharge water stop wall 161 is located at the bottom of the container 11 and is in contact with the inside, and blocks the plastic pieces P and the rinse water (alkaline water when the rinse is not performed) except when the container is discharged. The discharge water stop wall 161 and the discharge handle 163 are connected by a discharge rod 162. By pulling the discharge handle 163, the discharge water stop wall 161 moves from the position shown in FIG. 6 to the position shown in FIG. and rinsing water and the like are discharged from the discharge port 164 . At this time, the stirring mechanism 13 is preferably rotated at a low speed.
Note that the discharge mechanism 16 is not limited to the structure described above as long as it can discharge the plastic pieces P, rinse water, and the like. For example, like the example of the drainage mechanism 14, it can be electrically driven.

FIG. 8 is a schematic diagram showing the entire waste plastic recycling process including the deinking apparatus 1. As shown in FIG. In addition to the deinking device 1 , the recycling process includes a washing and pulverizing device 2 and a dewatering device 3 .
The washing and pulverizing device 2 is a device for simultaneously washing and pulverizing the waste plastic by using water or the like inside when the waste plastic is introduced from above.
The dehydrator 3 is a device for dehydrating plastic pieces using centrifugal force.

FIG. 9 is a schematic diagram showing the entire waste plastic recycling process including the dipping device 7. As shown in FIG.
Before the plastic pieces are applied to the deinking device 1, they are immersed in alkaline water for a short time (for example, 10 minutes) using the immersion device 7 to promote the decomposition of the paint and the like, shortening the time of the deinking process, and polishing. It is possible to enhance the deinking effect by In the deinking process by the deinking apparatus 1, the cover is closed and the process is performed at regular intervals. Therefore, the plastic pieces that flow sequentially from the previous process are received by the dipping apparatus 7 and stored. so that it can be used effectively.

When the deinking device 1 is not provided with the drainage mechanism 14 and the flooding mechanism 15 and the deinking device 1 does not perform rinsing, the first rinsing device 4 and the second rinsing device 5 are further provided.
The first rinsing device 4 is a device that uses hot water to wash away peeled paint and alkaline water from the plastic pieces.
The second rinsing device 5 is a device for further washing away impurities from the plastic pieces with water.

FIG. 10 is a flow diagram showing a series of flows of the recycling process. Note that steps that can be omitted are enclosed by dashed lines. Further, the processes that can be performed by the deinking apparatus 1 are collectively surrounded by a solid line.
The washing and pulverizing step S1 is a step in which waste plastic is charged, and impurities are washed away while washing and pulverizing the waste plastic with water or the like at the same time.
The first dehydration step S2 is a step of dehydrating the water or the like used for washing in the previous step using centrifugal force.
The immersion step S3 is a step of immersing the plastic pieces in alkaline water. This step can be performed in the immersion device or in the deinking device 1 . As mentioned above, this step may not be provided.
The deinking step S4 is a step of polishing the plastic piece with the deinking apparatus 1 and peeling off the paint or the like.
The drainage step S5 is a step of draining alkaline water used for deinking. If the deinking apparatus 1 is provided with a drainage mechanism, it is performed inside the deinking apparatus 1. If not, it is discharged from the deinking apparatus 1 and transferred to the first rinsing apparatus.
The first rinsing step S6 is a step of using hot water to wash away the paint and the like peeled off in the previous step and alkaline water from the plastic pieces. If the deinking device 1 is provided with a drainage mechanism and a flood port, the deinking device 1 is equipped with a drainage mechanism.
The second dehydration step S7 is a step of dehydrating the water or the like used for washing in the previous step using centrifugal force.
The second rinsing step S8 is the step of again washing impurities from the plastic pieces with water. It is also possible to omit this step by rinsing only once.
The third dehydration step S9 is a step of dehydrating the water or the like used for washing in the previous step using centrifugal force. This step is not provided when the second rinsing step S8 is not performed.
Through the processes described above, the waste plastic collected as garbage is reduced to a size that is easy to use, washed, and recycled.

FIG. 11 is a flow diagram showing the devices that pass through in the recycling process.
The middle column represents the devices that are routed through, the left column represents the steps that are performed when routed through the left device, and the right columns represent the steps that are routed through the right device. Note that each branch can be appropriately combined. For example, it is possible to have a first rinsing device (right route) without a dipping device (left route).

According to the deinking method of the present invention, waste plastics can be deinked with less alkaline water than in the past and in a short time, and the cost of supplying solvents such as alkaline water and the cost of waste water and neutralization treatment can be reduced. This invention is not only useful, but can promote the recycling of plastics, and can be expected to make a great contribution to society.

1 Deinking device 11 Container 111 Opening 112 First inlet 113 First outlet 114 First heating wire 12 Lid 121 Second inlet 122 Second outlet 123 Vent 124 Second heating wire 13 Stirring mechanism 131 Rotating shaft 132 First Blade 133 Second blade 14 Drainage mechanism 141 Drainage cutoff wall 142 Drainage rod 143 Drainage handle 144 Drainage port 145 Drainage net 15 Flood mechanism 151 Flood wall 152 Flood rod 153 Flood handle 154 Flood mouth 155 Flood net 16 Discharge mechanism 161 Drainage Water stop wall 162 Discharge rod 163 Discharge handle 164 Discharge port 2 Washing and crushing device 3 Dewatering device 4 First rinsing device 5 Second rinsing device S1 Washing and crushing step S2 First dewatering step S3 Immersion step S4 Deinking step S6 First rinsing Step S7 Second dehydration step S8 Second rinsing step S9 Third dehydration step

Claims (1)

A step of storing plastic pieces obtained by pulverizing coated plastic in a container;
pouring the alkaline water into the container to the extent that the plastic pieces are just submerged without floating;
agitating the plastic piece and the alkaline water contained in the container;
draining the alkaline water from the container;
The plastic piece is deinked by being stirred and polished.
de-inking method.