JPH0825357A - Treatment of plastic waste article fitted with film - Google Patents

Abstract

PURPOSE:To easily and certainly peel a film even from a plastic waste article having a complicated three-dimensional curved surface by a physical method. CONSTITUTION:A waste article is ground into small pieces l each having a size becoming L/T>=2 in the relation between the min. length L and thickness T thereof and having a film on the surface on one end side in the thickness direction thereof and the small pieces 1 are transferred to a peeling device 4 while the films become upper or rear surfaces to peel the films from the small pieces 1 under shearing. Because of L/T>=2, the small pieces are stabilized in such a state that the films thereof become upper or rear surfaces necessarily. Further, by forming the small pieces, the surfaces of the films become almost flat. Therefore, the entire surfaces of the films of the small pieces can be brought into contact with the surface of the peeling device 4 and the films can be certainly peeled under shearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method for efficiently removing a coating film from a plastic waste product having a coating film such as an automobile waste bumper. The plastic waste treated according to 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 written 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 product is crushed and melted as it is, the coating film pieces are dispersed in the molten PP, and the recycled product regenerated from the coated product contains the coating film pieces. 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 such as bumpers.

As a method of removing a coating film from a waste such as a bumper, there is a method of physically peeling the coating film such as a vibration compression method and a shot blast method. Further, as a chemical treatment method, a method of removing a coating film with an alkali or a method of swelling a coating film with methylene chloride and peeling it off (Japanese Patent Laid-Open No. 5-847)
No. 46) is known. There is also a method of peeling the coating film by immersing it in an organic salt solvent.

[0005]

However, in the method of physically peeling, when the waste product has a complicated three-dimensional curved surface, not only it takes time to remove the coating film, but also it is completely removed. Is difficult and is not suitable for large-scale processing. Further, in the chemical peeling method, it is difficult to completely peel off the coating film by a method using methylene chloride or an organic salt, and if it is attempted to peel off completely, the processing time becomes long. In addition, it is necessary to treat the waste liquid, which may cause environmental problems.

Further, in recent years, a method of hydrolyzing a waste product with a coating film in hot water and reusing it without removing the coating film from the substrate has been considered. However, even with this method, if hydrolysis is attempted completely, the processing time becomes long and the productivity is reduced. Further, if the treatment is performed for a short time, undecomposed coating film may remain and the appearance quality of the recycled product may be impaired. In addition, a coating film using a melamine resin as a cross-linking agent is relatively easy to hydrolyze, but a coating film having urethane cross-linking is extremely difficult to hydrolyze, and a thick coating film with a lot of extender pigment such as putty is also available. It is difficult to hydrolyze, and there is a problem that the coating film type has selectivity. A coating film having excellent durability and a high cross-linking density is less likely to be chemically decomposed, and there is a trade-off between improving the durability of the coating film and easiness of decomposition.

The present invention has been made in view of such circumstances, and in the method of physically peeling a coating film, even if it is a plastic waste product having a complicated three-dimensional curved surface, the coating film can be easily and surely formed. The purpose is to peel off.

[0008]

A method for treating a plastic waste product with a coating according to the present invention, which solves the above-mentioned problems, has a size such that a plastic waste product with a coating has a minimum length L and a thickness T of L / T ≧ 2. And a crushing step of crushing into small pieces having a coating film on one end side surface in the thickness direction, and a transfer step of supplying the small pieces to a transfer means and transferring them to the peeling device while aligning the coating film to the upper surface or the lower surface. And a peeling step of shearing and peeling the coating film from the small pieces with a peeling device.

[0009]

In the processing method of the present invention, the plastic waste product with the coating film is first crushed into small pieces in the crushing step. Here, each of the small pieces has a size such that the minimum length L and the thickness T are L / T ≧ 2, and a coating film is present on the one end side surface in the thickness direction. The planar shape of the small piece is preferably rectangular, but may be triangular or irregular. The size of L can be increased if the coating surface is a flat surface, but it is desirable to make it small if the coating surface is a curved surface so that the coating surface of the small piece is as close to the planar surface as possible.

When L / T <2, it is difficult to align the small pieces so that the coating film is always on the upper surface or the lower surface in the transfer process, and it is difficult to surely peel off. In the transfer step, the small pieces are supplied to a transfer means such as a transfer conveyor and transferred to the peeling device. During this transfer, the pieces are aligned so that the applied coating is on the top or bottom. In the present invention, since the shape of the small piece is L / T ≧ 2, the small piece rolls due to vibration during transfer, etc., and the coating film is always stable in the state of being on the upper surface or the lower surface. You can

In the peeling step, since the coating film is always supplied to the peeling device in the state of being on the upper surface or the lower surface, the coating film can be surely brought into contact with the surface of the peeling device. Even if the waste product has a curved shape, the surface of the coating film becomes close to a flat surface by making it into a small piece, so that the entire surface of the coating film can be brought into contact with the surface of the peeling device. Then, by contacting the coating film and the peeling device and applying a shearing stress between the coating film and the base material,
A uniform and constant level of shearing force or more can be applied, and the shear peeling causes the coating film to be peeled from the substrate of the small pieces.

When the shearing force is applied, the small piece is 140
It is desirable to be heated to a temperature of ℃ or less. As a result, the coating film is softened to some extent, but the plastic of the base material, which is the thermoplastic resin, is further softened, and the adhesion strength between the coating film and the base material is reduced, so that peeling is further facilitated. However, if too much heat is applied, the coating film may become too soft and the effect of shearing force may be weakened, making complete peeling difficult.
The optimum temperature is 20 ° C.

In the present invention, since the coating film is always on the upper surface or the lower surface, it is possible to surely heat from the surface side of the coating film by heating from the vertical direction, and the heating efficiency is good.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. (Embodiment 1) FIG. 1 shows a schematic diagram of a coating film removing apparatus used in an embodiment of the present invention. This coating film removing device is composed of a belt conveyor 2 as a transfer means, a heating device 3 and a peeling device 4. (Crushing process) A scraped polypropylene bumper with a coating is crushed with a cutter such as a dicer to obtain a small square piece 1. As shown in FIG. 2, this small piece 1 is crushed into a substantially rectangular parallelepiped shape, and has a base material 10 and a coating film 11 on one end side surface in the thickness direction of the base material 10. The small piece 1 has a thickness (T) of 1 to 6 mm and a minimum length (L) of 2 to 12 mm, and all the small pieces 1 are crushed so that L / T ≧ 2. (Transfer step) The small piece 1 is supplied to the belt conveyor 2,
Transfer to the peeling device 4. At this time, the small piece 1 is unstable when the coating film 11 is not substantially parallel to the surface of the belt conveyor 2 and falls or rolls to cause the coating film 1 to fall.
1 is stable when it is on the upper or lower surface. In the present embodiment, the belt conveyor 2 is slightly vibrated during the transfer to help the unstable pieces move to a stable state, and the coating film 11 is surely aligned on the upper surface or the lower surface. are doing. (Heating step) Then, the small piece 1 having the coating film 11 on the upper surface or the lower surface is heated from both upper and lower surface sides by the heating device 3. This heating is performed by heater heating, and the small piece 1 is surely heated from the coating film 11 side. The heating temperature is about 90
C., whereby at least the vicinity of the coating film 11 of the base material 10 is softened, but the coating film 1 crosslinked with the melamine resin 1
1 has hardly softened. (Peeling Step) The peeling device 4 is composed of an upper member 40 and a lower member 41, the upper member 40 and the lower member 41 are opposed to each other with a space therebetween, and in a direction in which they approach each other and a direction in which they move away from each other by a driving unit (not shown). Can be moved. An upper blade 42 is slidably provided on the lower surface of the upper member 40, and a lower blade 43 is slidably provided on the upper surface of the lower member 41. And the upper blade 42 and the lower blade 43
Are configured to be independently driven in forward and reverse directions parallel to the transfer direction of the belt conveyor 2 by a driving means (not shown).

A small piece 1 transferred by a belt conveyor 2
Is transferred to the lower blade 43 after being heated by the heating device 3. Then, the rear end of the upper blade 42 sandwiches the small piece 1 with the front end of the lower blade 43, and the lower blade 43 is driven in the transfer direction.
2 is driven in the opposite direction to the transfer direction. Thereby, a shearing force acts on the small piece 1 between the upper surface and the lower surface, and the coating film 11 is peeled off from the softened base material 10.

That is, in this embodiment, since the small pieces are L / T ≧ 2, the coating film 11 surely becomes the upper surface or the lower surface and comes into contact with the upper blade 42 or the lower blade 43, and the shearing force surely. It can be peeled off. The base material 10 from which the coating film 11 has been peeled off can be melted again and used as a bumper raw material.

It is also preferable that the small piece 1 is subjected to a hydrolysis treatment after the peeling step. If you do this,
Even if a part of the coating film 11 remains on the surface of the substrate without being peeled off, the residual coating film is hydrolyzed and rendered harmless, so that it can be reused as it is. (Embodiment 2) FIG. 3 shows a schematic configuration diagram of a coating film removing apparatus used in Embodiment 2. This coating film removing device is the same as that of the first embodiment except that the configurations of the belt conveyor 2 and the peeling device 4 are different.

The belt conveyor 2 can be partially moved vertically at the position of the peeling device 4. The peeling device 4
Is composed of a pair of shearing force imparting rollers 44 and 45 and a pair of slag removing rollers 46 and 47. The large-diameter shearing force application rollers 44 and 45 are rotationally driven in the transfer direction, but one rotational speed is higher than the other rotational speed. Similarly, the small-diameter slag removing rollers 46 and 47 are also rotationally driven in the transfer direction, but the rotational speed of one is higher than that of the other.

In this coating film removing apparatus, a small piece 1 similar to that of the embodiment is supplied to the belt conveyor 2. And Example 1
After being heated from both upper and lower surfaces by the heating device 3 in the same manner as described above, the small piece 1 is also paired with the shearing force application roller 4 by utilizing the force of gravity.
It is sandwiched between 4,45. Then, the coating film 11 is peeled from the base material 10 by the shearing force acting from the pair of shearing force imparting rollers 44 and 45.

That is, since the small pieces are L / T ≧ 2 also in this embodiment, the coating film 11 surely comes into contact with one of the pair of shearing force imparting rollers 44 and 45, and the coating film 11 is surely secured by the shearing force. Can be peeled off. Next, in this embodiment, in consideration of the case where the shavings 12 remain on the surface of the base material 10, shavings removing rollers 46 and 47 having a small diameter are arranged. That is, the small piece 1 is further subjected to shearing force from the cutting waste removing rollers 46 and 47, and the radius of curvature of the cutting waste removing rollers 46 and 47 is small, so that the shearing force can be concentrated in a narrow range, and the cutting waste 12 can be surely cut. It is peeled off.

Although the heating device 3 is separately provided in this embodiment, the pair of shearing force applying rollers 44 and 45 themselves may be used as the heating device. In this case, the heating step and the shearing step are performed almost simultaneously. Further, in the present embodiment, the rotational speeds of the pair of rollers are made different from each other to give the shearing force to the left and right, but the shearing force can also be given by making the diameters of the pair of rollers different to the left and right.

Although the embodiments of the present invention have been described above, the embodiments of the present invention have various technical aspects as described below in addition to the technical matters described in the claims. It is added that (1) The method for treating a plastic waste product with a coating film according to claim 1, wherein a heating process of heating the small piece from the surface side of the coating film is performed before the peeling process.

[0023]

[Effects of the Invention] That is, according to the method for treating plastic waste products with a coating film of the present invention, since the shearing force acts on the coating film with certainty, the coating film can be surely peeled off from the substrate, so that the putty etc. A thick coating film can be easily peeled off. Therefore, even a waste product having a complicated shape can be easily reused as a base material only. Moreover, since it is not a chemical removal method, there is no problem of environmental pollution.

Furthermore, since the small piece having a simple shape similar to a flat plate is used, the transfer speed and the peeling speed can be increased, and the mass productivity is improved. Moreover, since the entire system is compact, the equipment is inexpensive and the operating cost is also low. Therefore, the cost of the reused raw material can be reduced, and it can be positively used as a substitute for a new raw material.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a schematic configuration of a coating film removing apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a small piece used in an embodiment of the present invention.

FIG. 3 is a schematic front view showing a schematic configuration of a coating film removing apparatus used in a second embodiment of the present invention.

[Explanation of symbols]

1: Small piece 2: Belt conveyor
3: Heating device 4: Stripping device 10: Substrate 1
1: Coating film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Okada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A crushing step of crushing a coated plastic waste product into small pieces having a minimum length L and a thickness T of L / T ≧ 2 and having a coating film on one end side surface in the thickness direction. A transfer step of supplying the small pieces to a transfer means and transferring them to a peeling device while aligning the coating film so that the coating film is on the upper surface or the lower surface; and a peeling step of shearing and peeling the coating film from the small pieces by the peeling device. A method for treating a plastic waste product with a coating, which comprises: