JPH07108532A - Recycling treatment for waste material of synthetic resin with coating film - Google Patents

Abstract

PURPOSE:To conduct recycling in a short time by chopping synthetic resin waste materials with a coating film, and heating and stirring the chopped waste material supplied with water for hydrolyzing the coating film on the surface of the chipped materials, and then cutting them through the action of shearing stresses for separating the chopped materials from water. CONSTITUTION:Waste bumpers are turned with the use of a chopping device into chopped materials with a coating film having the square size of the order of 5mm, to then be stored within a hopper 10. A predetermined quantity of water is supplied from the water supply pipe 31 Into the pressure vessel 1, and a valve 34 is closed for rotating the stirring blades 21 and a bridge breaker 22. Then the chopped materials within the hopper 10 is put to be stirred into the vessel 1 by opening the valve 11. The number of revolutions is increased for stirring water and the chopped materials uniformly. Supplied from a steam supply pipe is steam for heating the inner part of the vessel 1. By the heating and stirring, a coated film on the chopped materials comes to be swelled, and besides, the coated film is separated from the chopped materials through collision against the blades 21 and shearing stresses affected thereto. Herein, the separation of water from the chopped materials is achieved. Accordingly, the coating film is made into separation or fine pieces, so that the chopped materials can be recycled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reprocessing method for efficiently decomposing and removing a coating film from a coated resin waste material such as a bumper of a waste automobile. The synthetic resin waste material treated by the present invention can be reused for manufacturing bumpers and the like.

[0002]

2. Description of the Related Art In recent years, the reuse of waste products has become an issue for the purpose of reducing the number of man-hours spent on environmental pollution and waste treatment and using limited resources without waste. For example, in automobiles, although metal materials such as steel plates have been reused for a long time, resin parts have generally been incinerated conventionally. So in recent years,
Material names are entered on resin parts, and the same materials are collectively melted and reused.

However, a large part such as a bumper has a structure in which a base material such as polypropylene (PP) is coated with a coating film of thermosetting paint. Therefore, when the waste material is crushed and melted as it is, the pieces of the coating film are dispersed in the molten PP, and the pieces of the coating film are included in the recycled product regenerated from the PP. Therefore, the physical properties of the recycled product may deteriorate,
In many cases, the appearance quality is inferior, and it is desired to establish a method for removing the coating film from waste materials such as bumpers.

As a method of removing a coating film from a waste material such as a bumper, there is a method of physically peeling the coating film by, for example, shot blasting. However, when the waste material has a complicated shape, not only is it time-consuming to remove the coating film, but it is difficult to completely remove it, which is not suitable for large-scale processing. As a chemical treatment method, JP-A-5-84746 discloses a method of swelling a coating film with methylene chloride and peeling it off. There is also a method of peeling the coating film by immersing it in an organic salt solvent. However, with the method using methylene chloride or an organic salt, it is difficult to completely peel off the coating film, and even after peeling, it is necessary to completely separate and remove the coating film. Become. In addition, it is necessary to treat the waste liquid, which may cause environmental problems.

[0005]

Therefore, the applicant of the present application is
A method has been proposed in which a coating-coated waste material is hydrolyzed in hot water and can be reused without removing the coating from the substrate (Japanese Patent Application No. 3-192431). However, even with this method,
If it is attempted to hydrolyze completely, the processing time becomes long and the productivity decreases. Further, if the treatment is carried out for a short time, the undecomposed coating film may remain and the appearance quality of the recycled product may be impaired. The particle size of the coating film piece in the recycled bumper formed from the treated waste material obtained by this method is as large as about 150 μm at maximum, as shown in FIG. 3, for example, and many particles of 50 μm or more are contained. is there.

The present invention has been made in view of such circumstances, and it is an object of the present invention to decompose and remove a coating film to such an extent that there is no problem when it is made into a recycled product by a short-time treatment, and to overcome environmental problems. To aim.

[0007]

A method for recycling a coated synthetic resin waste material according to the present invention, which solves the above-mentioned problems, includes a pulverizing step of pulverizing a coated synthetic resin waste material into a pulverized material, and a pulverized material. A treatment process in which water is mixed with a treatment liquid mainly, heated to a predetermined temperature and stirred to hydrolyze the coating film on the surface of the pulverized material and to apply shear stress to the coating film, and the pulverized material after the treatment step Is separated from the treatment liquid.

[0008]

In the recycling method of the present invention, the coated synthetic resin waste material is first crushed into a crushed material. It is more desirable that the size of the crushed material be smaller, but from the viewpoint of handling workability and crushing time, it is suitable that the size is about 5 mm square. In the treatment step which is a feature of the present invention, the pulverized material is mixed with the treatment liquid and heated and stirred. Here, as the treatment liquid mainly composed of water, it is also possible to use one obtained by adding an acid or alkali to water, one obtained by adding an organic substance such as alcohol to water, but from the viewpoint of environmental problems, only water is used. Is desirable.

A higher heating temperature in the treatment step is preferable because the hydrolysis reaction is promoted, but it is necessary to be lower than the melting point of the waste material base material. 1 if the waste material base material is PP
The range of 30-160 degreeC is preferable. Pressure is preferably applied in order to keep the treatment liquid in the liquid state in this temperature range. In the treatment step, the coating film is subjected to a hydrolysis reaction and a shear stress due to stirring at the same time. That is, the main chain and side chains are broken by the hydrolysis reaction in the coating film, and water is easily infiltrated and is in a swollen state. When the shear stress acts in that state, the coating film is easily divided, and the shape of one coating film piece becomes smaller, and in many cases, it separates from the ground material base material. In addition, the smaller size of the coating film piece further promotes the hydrolysis reaction.

In the separating step, the coating film pieces separated from the waste material base material are separated from the pulverized material, and the pulverized material is separated from the treatment liquid and reused.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples. Figure 1
A sectional view of the hydrolysis apparatus used in this example is shown in FIG. This hydrolysis device comprises a pressure vessel 1, a stirring device 2 rotatably arranged in the pressure vessel 1, a supply pipe 3 for supplying water and steam into the pressure vessel 1, and water in the pressure vessel 1. It is mainly composed of a recovery pipe 4 for recovery.

The pressure vessel 1 is provided with a hopper 10,
The crushed material in the hopper 10 is configured to drop into the pressure vessel 1 by opening the valve 11. Further, the pressure vessel 1 is provided with a level sensor 12 and a temperature sensor 13,
The water level and temperature of the processing liquid in the pressure vessel 1 can be detected. The contents of the pressure vessel 1 can be discharged by opening a discharge valve 14 provided at the bottom.

The stirring device 2 has a rotating shaft 20 arranged eccentrically from the center of the pressure vessel 1, a stirring blade 21 fixed below the rotating shaft 20, and a tip of the rotating shaft 20 further below the stirring blade 21. A bridge breaker 22 fixed to
It is composed of a motor 23 and a transmission 24 that rotationally drive the rotary shaft 20. The supply pipe 3 is a steam supply pipe 30.
And a steam mixer 32 to which a water supply pipe 31 is connected. Then, the recovery pipe 4 is connected to the water supply pipe 31, and a circulation circuit is configured in which the water recovered from the pressure vessel 1 is mixed with steam and returns to the pressure vessel 1 again.

Now, using the hydrolysis device constructed as described above, the PP waste bumper for automobiles is regenerated.
The waste bumper is made of PP base material and acrylic applied on its surface.
It is composed of a melamine-based coating film and / or an alkyd melamine coating film. First, the waste bumper is supplied to a crushing device (not shown), is made into a crushed material with a coating film of about 5 mm square, and is temporarily stored in the hopper 10.

A predetermined amount of water measured by a flow meter 33 is supplied into the pressure vessel 1 from a water supply pipe 31, and a valve 34
Is closed. Next, the motor 23 is driven and the transmission 24
The rotary shaft 20, the stirring blade 21, and the bridge breaker 22 are rotationally driven at 150 r / min via the. Then, the valve 11 is opened while stirring, and the pulverized material in the hopper 10 is put into the pressure vessel 1.

After the total amount of the pulverized material has been added, the valve 11 is closed,
The speed of the stirring blade 21 is adjusted to 180 by adjusting the transmission 24.
Increase to r / min. Since the specific gravity of PP is 0.95, which is smaller than that of water, the pulverized material generally floats on water and uniform stirring is difficult. However, in this embodiment, by devising the shape of the stirring blade 21, a downward flow is generated in the rotation center part of the mixture of water and the pulverized material, and an upward flow is generated in the outer peripheral part due to the above-mentioned rotation speed, and the whole Are uniformly stirred.

In the sealed pressure vessel 1, the pump 40 provided in the recovery pipe 4 is driven to circulate water.
At the same time, the valve 35 is opened, and the circulating water is supplied from the steam supply pipe 30 to the steam and steam mixer 32.
Are mixed and supplied into the pressure vessel 1. In this way, the pressure vessel 1 is heated to 160 ° C. and kept at 160 ° C. for 1 hour. The temperature inside the pressure vessel 1 is detected by the temperature sensor 13,
160 ℃ by controlling the opening of valve 35 by PID
Keep constant. Further, the water level in the pressure vessel 1 is increased by the condensed water content of the steam, but the water level is detected by the level sensor 12, and when the water level exceeds a predetermined level, the drain valve 36 is opened to discharge the water to the outside to maintain a constant level. .

The pulverized material in the reaction vessel 1 is agitated. At this time, the PP base material maintains the shape of the pulverized material to some extent.
Further, if the treatment temperature is too high, the base materials themselves are softened / melted and the base materials are fused to each other to form a dumpling, and if the coating film is taken inside the dumpling, it is not hydrolyzed. Therefore, the processing temperature is set to a temperature at which the base materials do not fuse with each other. The coating film is hydrolyzed with hot water at 160 ° C. and becomes swollen with hot water. In that state, a strong stirring action is exerted by the stirring blade 21, and due to the collision with the stirring blade 21, the collision with the inner wall of the pressure vessel 1 and the collision between the pulverized materials, a large shear stress acts on the coating film. Therefore, the coating film is separated from the pulverized material base material or is divided even if it is not separated, whereby the size of the coating film piece attached to the pulverized material becomes extremely small. The peeled coating film flows together with the circulating water and is filtered by the filter 41, so that it does not return to the reaction container 1 again. Further, the container and the stirring blade 21 are not always in contact with the pulverized material, and thus are not easily contaminated.

After the processing, the valve 35 is closed and the rotation speed is 1
The pressure is reduced to 50 r / min and the pressure reducing valve 15
Is opened and the pressure in the reaction vessel 1 is reduced to atmospheric pressure. Since the water in the reaction vessel 1 evaporates during the pressure reduction process, the temperature inside the reaction vessel 1 is lowered to about 100 ° C. After decompression is completed,
Water is introduced from the water supply pipe 31 and further cooled. The temperature inside the reaction vessel 1 is 40 ° C after repeated introduction and discharge of water.
Then, the valve 14 is opened, and the crushed material after the treatment is naturally dropped together with water. Since the coating film on the surface of the ground material base material which has been hydrolyzed is very tacky, it is possible to prevent clogging of the discharge port due to adhesion of the ground material materials by discharging together with water. At this time, the rotation of the bridge breaker 22 prevents the occurrence of bridges. Then, after the entire amount of the crushed material after the treatment is discharged, the driving of the rotary shaft 30 is stopped, and one cycle of the treatment is completed.

The treated pulverized material thus obtained is kneaded and melted together with the PP material and then pelletized to become a recycled bumper material. The particle size of the coating film piece in the bumper formed from this recycled bumper material was measured by microscopic observation, and the result is shown in FIG.
The measurement was omitted for particles having a particle size of 5 μm or less. Figure 2
As shown in, even the coated film piece having the maximum particle size was 40 μm or less, and the average particle size was 11 μm. As a result, the physical properties and appearance quality of the obtained recycled bumper were equivalent to those of the new PP bumper.

Further, since dirt such as oil and mud adhered to the waste material before treatment is washed by contact with hot water, it is not necessary to provide a washing step.

[0022]

That is, according to the method for recycling a coated resin waste material with a coating film of the present invention, the coating film can be decomposed and removed to such an extent that it does not cause any trouble when a recycled product is treated in a short time. Productivity is dramatically improved. Further, since the treatment liquid can be composed only of water, environmental problems do not occur and the treatment of the waste liquid is extremely easy.

Since the pulverized material obtained by the present invention has a small size of the adhered coating film pieces, the physical properties and the surface appearance of the pulverized material are hardly deteriorated when the pulverized material is regenerated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a processing apparatus used in an embodiment of the present invention.

FIG. 2 is a graph showing the particle size distribution of coating film pieces in a recycled bumper formed from ground material treated in one embodiment of the present invention.

FIG. 3 is a graph showing a particle size distribution of coating film pieces in a recycled bumper formed from a pulverized material treated by the prior invention of the present invention.

[Explanation of symbols]

1: Pressure vessel 2: Stirring device 3: Supply pipe 4: Recovery pipe 10: Hopper 21: Stirring blade 32: Steam mixer

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Claims (1)

[Claims] 1. A pulverization step of pulverizing a coated synthetic resin waste material into a pulverized material, and mixing the pulverized material with a treatment liquid containing water as a main component, heating the mixture to a predetermined temperature, and stirring the mixture. A coating process comprising a treatment step of hydrolyzing the coating film on the surface of the material and applying a shear stress to the coating film, and a separation step of separating the pulverized material after the processing step from the treatment liquid. Recycling method for waste synthetic resin with film.