JPH0724832A - Coated film peeling method for coated thermoplastic product and method and apparatus for regeneration - Google Patents

Abstract

PURPOSE:To efficiently peel and remove a coated film by utilizing a difference of elongations of the film which is not plastically deformed and two- dimensionally spreading thermoplastic. CONSTITUTION:A method for peeling a coated film of a coated thermoplastic product, a method and an apparatus for regenerating comprise the steps of heating a thermoplastic product 1 having a coated film 1b in which thermoplastic 1a is coated with thermosetting plastic paint to elongate it, removing the film 1b peeled by the elongating by coated film removing means 6, pulverizing only the remaining plastic 1a, kneading, melting it and molding it, thereby obtaining a pellet of high quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a coating film of a coated thermoplastic product and a method and apparatus for reprocessing the same.
It relates to a new improvement for regeneration and pelletization.

[0002]

2. Description of the Related Art Conventionally, in the case of recycling a plastic product having a coating film, as a first conventional example, generally, the coating film is crushed by a crusher as it is without being peeled off, which is then extruded or press molded. It was used after being molded into a recycled product by a machine. In addition, recently, as a second conventional example, research has been conducted to remove a coating film and then reuse it. This is a method of removing the coating film with an organic solvent. The crushed plastic product with a coating film is immersed in a solvent solution tank consisting of organic salts, etc., only the plastic is separated and separated with a separator, washed with water, dried, and then extruded with an extruder. It has been proposed to pelletize and reuse. Furthermore, as a third conventional example, a plastic product having a coating film is crushed,
Although a method of mechanically compressing with a vibration compressor to make the coating film easy to peel off and removing the coating film with a pin mill has been studied, the amount of residual coating film is large, and after melting with an extruder, the residual coating film with a metal wire mesh is used. Research has been conducted on recycling by removing the film.

[0003]

Since the conventional method for removing the coating film of the coated thermoplastic resin product is configured as described above, the following problems exist. 1. First, in the first conventional example, since the coating film is reused as it is without being peeled off, the physical properties are deteriorated and the coating film piece floats on the surface of the product to deteriorate the appearance. Therefore, the reproduction quality is low, and for example, it is only used for a park bench, a fence or a block used as a substitute for paving stones. 2. The method of using a solvent such as an organic salt of the second conventional example is
If the used solvent is disposed of as it is, it causes environmental pollution. Therefore, the cost for detoxifying becomes large, and the detoxifying treatment is necessary for the water used for washing, and the apparatus becomes large. 3. The third conventional example is a method of mechanically compressing to facilitate peeling of a coating film. A plastic coated in a minute gap is allowed to pass through at room temperature to cause plastic deformation in the plastic portion instantaneously and shift to the interface with the coating film. Is something that causes Therefore, a large amount of force is applied, so that the plastic portion is pulverized, and the coating film cannot be peeled off, but remains at about 50% or more. Therefore, after melting with an extruder, it was necessary to further filter the residual coating film with a metal wire mesh. In addition, when separating the paint film and the plastic part, about 15 of finely pulverized plastic is used.
It was difficult to collect about%. Further, since the treatment is carried out at room temperature, most of the coating film is easily peeled off, and 50% or more of the coating film remains even if the coating film is peeled off by an auxiliary impact. This method requires a large amount of equipment cost and requires a large amount of reprocessing cost.

The present invention has been made to solve the above problems. In particular, a coating film, which is a thermosetting plastic, has the property of not being plastically deformed, and a thermoplastic plastic is plastically deformable. Utilizing the property that there is a difference between the two-dimensional spread and the expansion due to the thermal expansion due to heating, the coated film is efficiently peeled and removed, regenerated and pelletized. An object of the present invention is to provide a method for removing a coating film of a plastic product and a method and apparatus for recycling treatment.

[0005]

A method for removing a coating film from a coated thermoplastic product according to the present invention comprises heating a thermoplastic product having a coating film formed by coating a thermoplastic with a thermosetting plastic paint. And a second step of removing the coating film after the completion of the first step.

More specifically, in the first step,
This is a method using a compression molding machine.

More specifically, in the first step,
This is a method using a rolling roll.

More specifically, in the first step,
This is a method using a biaxial stretching device.

More specifically, in the second step,
This is a method using an air jet.

More specifically, in the second step,
This is a method using a wire wheel.

More specifically, in the second step,
This is a method using a water jet.

A method for recycling a coated thermoplastic product according to the present invention comprises carrying, heating and stretching a thermoplastic product having a coating film formed by coating a thermoplastic with a thermosetting plastic paint. After that, the coating film is removed, and the thermoplastic plastic is crushed, kneaded, melted, and molded.

According to the present invention, there is provided a recycling apparatus for a coated thermoplastic product, a transport means for transporting a thermoplastic product having a coating film formed by coating a thermoplastic with a thermosetting plastic paint, and the transport means. The coating film was removed from the coated thermoplastic resin by a stretching means having a heating means arranged on the downstream side of the means, a coating film removing means, a crushing means, a kneading and melting means and a molding means. The configuration is such that it is post-molded.

More specifically, the stretching means provided with the heating means is a compression molding machine.

More specifically, the stretching means provided with the heating means is a rolling roll.

[0016]

In the method and apparatus for removing a coating film from a coated thermoplastic product and the method and apparatus for recycling according to the present invention, first, the coating film is removed from the coated thermoplastic product. Painted thermoplastic products are generally painted with a primer, which is a thermosetting plastic. Even if the primer itself is thermoplastic, it becomes thermosetting when the thermosetting plastic is applied and heat treated. Thermoplastics have the property of being plastically deformed and expanded by being crushed or stretched. On the other hand, the thermosetting plastic that is the coating film,
It does not spread easily even if it is crushed or stretched. Further, by heating, the thermoplastic is more likely to be plastically deformed. Therefore, when a thermoplastic product coated with a thermosetting plastic coating is heated and crushed or stretched, the thermosetting plastic is easily plastically deformed and stretched, and the thermosetting plastic coating is coated. Displacement due to the difference in elongation occurs at the boundary surface with the film, and the coating film is pulled by the thermoplastic and physically breaks and peels off. The coating film containing the primer thus peeled from the surface of the thermoplastic product is removed by a mechanical operation. The heating temperature of the thermoplastic product is within a range not exceeding the softening temperature or the melting temperature of the thermoplastic, and the higher the heating temperature, the easier the plastic deformation of the thermoplastic is, which reduces the force for rolling or stretching, The time can be shortened. The thermoplastic film product from which the coating film has been peeled off and removed is crushed by crushing means, if necessary, by crushing means, then kneaded and melted by kneading and melting means, and formed into a string (strand) by the forming means,
Pelletized with a pelletizer.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for removing a coating film of a coated thermoplastic resin product according to the present invention and a method and an apparatus for recycling treatment according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing a method for peeling a coating film of a thermoplastic product according to the present invention, and FIGS. 2 and 3 show a coating film peeling and a reclaiming process of a thermoplastic product coated with a thermosetting plastic, respectively. It is a block diagram of the 1st Example and 2nd Example of the system apparatus shown. In FIG. 1, reference numeral 1 denotes, for example, a painted thermoplastic product (hereinafter referred to as a product) obtained by appropriately cutting an automobile bumper, and the product 1 is a thermoplastic resin made of polypropylene resin or the like. Plastic 1a
And a coating film 1b made of a thermosetting plastic coating applied to the thermoplastic resin 1a after primer coating. The coating film 1b contains the primer coating and is heat-treated. When the product 1 having such a configuration is heated from the state of FIG. 1A by the stretching means 5 provided with a heating means and stretched, the thermoplastic 1a is plastically deformed by the mechanical stretching and two-dimensionally stretched. On the other hand, since the coating film 1b is not extended, the coating film 1b is not extended, so that the coating film 1b is pulled by the thermoplastic resin 1a, is broken, and is peeled off due to the displacement at the boundary surface, and is separated as shown in FIG. It floats from 1a and is in a slightly adhered state. After that, the coating film 1b attached to the surface of the thermoplastic 1a is removed by the removing means. At this time, coating film 1
It is desirable that the removal process of b is performed as soon as possible after the immediately preceding stretching process while the thermoplastic resin 1a and the coating film 1b are heated. In the heated state, the coating film 1b is easily removed, but when the temperature returns to room temperature, the adhered state becomes a little stronger and the removal work becomes difficult.

Next, FIG. 2 is a schematic constitutional view showing an example of an apparatus in which a compression molding machine 5a is applied as a stretching means 5 having a heating means in the coating film peeling method and the reclaiming method according to the present invention. That is, the reference numeral 2 in FIG. 2 is a conveying means composed of a conveyor for conveying the product 1, and downstream of the conveying means 2 is a cutting means 3 composed of a cutting device and a heating device. Kneading and melting consisting of heating means 4, stretching means 5 consisting of a compression molding machine, coating film removing means 6 consisting of a wire wheel, crushing means 7 consisting of a crusher, supply / transport means 8, feeder 9, and extruder having a vacuum pump 11. A means 10, a forming means 14 including a porous die 12 and a cooling water tank 13, and a pelletizer 16 for obtaining regenerated pellets 15 are arranged in series. The coating film removing means 6 may be an air jet or a water jet.

Next, a method of actually peeling and regenerating the coating film will be described. As shown in FIG. 2, product 1
Are sequentially conveyed by the conveyor 2, and the product 1 is cut by the cutting means 3 into an appropriate size in order to facilitate post-treatment. However, if the size of the product 1 is large enough to be processed by the subsequent processing device, the cutting step is omitted. Then, the product 1 is heated through the continuous heating means 4. Next, the above-mentioned heated product 1 is rolled by using the compression molding machine 5a, and the thermoplastic plastic 1a is two-dimensionally spread in the direction of the coating surface and stretched. At this time, painted film 1
Although b is also spread at the same time but does not extend, it can be pulled by the thermoplastic 1a, mechanically ruptured and peeled off.

Next, the peeled coating film 1b is removed from the vertical direction of the flat plate-shaped product 1 using the coating film removing means 6. In this way, the crushing means 7 crushes the thermoplastic resin 1a from which the coating film 1b has been peeled off. The crushed thermoplastic 1a is sent to the next kneading and melting means 10 by the supply and transportation means 8 and stored in the feeder 9. Further, this kneading and melting means 10
Melts the crushed thermoplastic 1a and extrudes it into a string (strand) with a porous die 12.
It is cooled by passing through the cooling water tank 13. Next, it is cut into pellets by the pelletizer 16. Further, the coating film 1a removed by the wire wheel 6 is removed to the outside by a vacuum means (not shown). In the embodiment of FIG. 2, the compression molding machine 5a is usually provided with a heating means, and the product 1 can be heated and extended only by the compression molding machine 5a. By providing the heating means 4 on the upstream side and preheating the product 1 within a range not exceeding the softening temperature or melting temperature of the thermoplastic 1a, it is possible to shorten the time required for the stretching process and improve the processing efficiency. Becomes Next, FIG. 3 is a schematic configuration diagram showing an example of an apparatus to which a rolling roll 5b is applied as the stretching means 5 in the coating film peeling method and the reprocessing method according to another embodiment of the present invention. That is, in FIG. 3, the reprocessing apparatus is composed of a crushing means 7, a supply / transport means 8, a feeder 9, a rolling roll 5b provided with a heating means, and a pin mill 18 downstream of the transport means 2 for transporting the product 1. Kneading and melting means 10 comprising an extruder having a coating film removing means 6, a supply and transport means 8, a feeder 9, and a vacuum pump 11,
Forming means 14 comprising a porous die 12 and a cooling water tank 13.
And pelletizer 16 for obtaining regenerated pellets 15
Are arranged in series, respectively. In the reprocessing apparatus configured as described above, the product 1 conveyed and supplied to the crushing means 7 by the conveying means 2 becomes 5 by the crushing means 7.
Crush into small pieces ~ 7 mm in size. The crushed product 1 is supplied to the rolling roll 17 via the supply / transport means 8 and the feeder 9. The small pieces of the product 1 are rolled and stretched by the rolling roll 5b heated to a temperature that does not exceed the softening temperature or melting temperature of the thermoplastic resin forming the product 1, and the coating film is peeled off. The small pieces of the product 1 from which the coating film has been peeled off are supplied to the pin mill 18, and the coating film is separated by a large number of pins that rotate at high speed. The small pieces of the product 1 from which the coating film has been separated are referred to as the supply transport means 8,
The feeder 9, the kneading and melting means 10, the molding means 14 and the pelletizer 16 perform the same processing as in the recycling processing apparatus shown in FIG. It is also possible to provide a plurality of rolling rolls 5b and perform the treatment a plurality of times in order to perform the stretching, that is, the peeling process more effectively. Further, similarly to the embodiment shown in FIG. 2, by providing the heating means 4 on the upstream side of the rolling roll 5b to preheat the product 1 crushed into small pieces, the processing efficiency can be improved. Further, in the processing apparatus of each of the above-described embodiments, even if the temperature of the heating means provided in the stretching means 5 is set to the softening temperature or the melting temperature of the thermoplastic 1 or higher, if the processing time in the stretching means 5 can be appropriately controlled, The coating film 1b can be peeled off.

Next, an example actually carried out by the applicant will be described. The product 1 is a bumper for an automobile, which is made of polypropylene and has a primer and urethane coating film 1b (about 40 to 70 μm). The product 1 is cut into an appropriate size, and a stretching means 5 including a compression molding machine 5a is used. Was rolled. Pressing surface pressure during rolling is 225kg
/ Cm ² . The mold plate temperature during molding was set to 160 ° C. The coating film 1b could be completely peeled off when the compression time was 10 seconds. Next, pressing surface pressure during rolling 88kg / cm
^{2. When} the mold plate temperature was 175 ° C., the coating film 1b could be peeled off with a holding time of 10 seconds. In addition, peeling was possible even with a holding time of 8 seconds. Further, when the holding time was set to 30 seconds, only the polypropylene resin constituting the thermoplastic 1a of the product 1 was melted and flowed, spread widely and adhered to the mold board. It could not be removed without cooling. The coating film 1b remained in the same size, and was re-bonded to the melted polypropylene resin and was not peeled off. Next, when the pressing surface pressure during rolling was 28 kg / cm ² and the mold plate temperature was 225 ° C. and the holding time was 15 seconds, the polypropylene resin instantaneously melted and flowed, and the coating film 1 b
Could not be peeled off.

Next, the pressing surface pressure during rolling is 148 kg / cm.
^{2. With} a mold plate temperature of 150 ° C, a coating film 1 with a holding time of 30 seconds
b could be peeled off. Under this condition, hold time is 5
It could not be peeled off in seconds. As described above, the melting point of the polypropylene resin is 162 ° C., and if the temperature of the mold plate is equal to or higher than the melting point, the polypropylene resin must be rolled in a short time so that the polypropylene resin does not melt, and the timing of the peeling process becomes very difficult. In particular, at a high temperature such as 225 ° C., the polypropylene resin melts and flows instantaneously and cannot be peeled off.

When flowing, the reason why the coating film 1b cannot be peeled off is that the tensile strength of the coating film is larger than the spreading force of the polypropylene resin, so that the coating film cannot be broken. Therefore, when the peeling treatment is performed at a temperature equal to or lower than the melting point of the polypropylene resin, the force spreading by plastic deformation of the polypropylene resin is larger than the tensile strength of the coating film 1b, so that the coating film 1b is mechanically cut into pieces and the polypropylene resin is separated. A deviation occurs in the boundary surface between the coating film 1b and the coating film 1b, and the coating film 1b is peeled off. next,
Similar results were obtained with rolling rolls. However, when a roll is used, it is necessary to pass a plurality of rolls in order to secure the holding time.

Further, a test was carried out using a biaxial stretching device, and it was found that the coating film 1b could be sufficiently peeled by stretching the polypropylene resin bumper by about 1.5 times the longitudinal and transverse dimensions. When using a biaxial stretching device, it is necessary to make the shape of the cut product 1 the same. In addition, although the automobile bumper has been described in the above-described embodiments, the present invention can be applied to other home electric appliances and the like in which a thermoplastic resin product is coated with a thermosetting plastic paint. Further, when the heating temperature is near the melting point or the softening point, the stretching force can be reduced, and the holding time for heating can be short. Next, when the minimum heating temperature is about 55 ° C., the tensile strength of the coating film decreases, so heating above this temperature is required.

[0025]

EFFECTS OF THE INVENTION The coating film peeling method, the recycling treatment method and the apparatus for the coated thermoplastic product according to the present invention are configured as described above, and therefore the following effects can be obtained. That is, due to the difference between the stretch of the coating film, which is a thermosetting plastic constituting the product, and the thermoplastic when stretched, or the stretch when rolled,
The coating film can be mechanically broken and peeled off. In particular, by carrying out at a high temperature which does not exceed the melting point and softening point, the effect is accelerated due to deterioration of mechanical properties of the thermosetting plastic and increase of elongation of the thermoplastic.
In this way, it can be peeled off relatively easily.
It is possible to obtain high-quality recycled plastic that was difficult to put into practical use. Moreover, since no solvent or the like is used for peeling and removing, the coating film can be completely peeled and removed without causing secondary pollution. Therefore, it is possible to obtain a method in which the apparatus cost is low and the peeling process cost is sufficiently profitable.

[Brief description of drawings]

FIG. 1 is a structural diagram showing a method for removing a coating film and a recycling treatment method for a coated thermoplastic product according to the present invention.

FIG. 2 is a configuration diagram showing a system to which a coating film peeling method and a recycling treatment method of a coated thermoplastic product according to the present invention are applied.

FIG. 3 is a configuration diagram showing another embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Painted thermoplastic product (product) 1a Thermoplastic (polypropylene resin) 1b Coating film 2 Conveying means 3 Cutting means 4 Heating means 5 Spreading means equipped with heating means 6 Coating film removing means 7 Crushing means 10 Kneading and melting Means 14 Forming means

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[Procedure amendment]

[Submission date] August 6, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Claims (11)

[Claims] 1. A thermoplastic plastic product (1) having a coating film (1b) obtained by coating a thermoplastic resin (1a) with a thermosetting plastic paint by heating and stretching the thermoplastic plastic product (1).
A method for removing a coating film from a coated thermoplastic product, comprising the steps of: and a second step of removing the coating film (1b) after the completion of the first step. 2. The method for removing a coating film from a coated thermoplastic product according to claim 1, wherein a compression molding machine is used in the first step. 3. The coating film peeling method for a coated thermoplastic product according to claim 1, wherein a rolling roll is used in the first step. 4. The method for peeling a coating film from a coated thermoplastic product according to claim 1, wherein a biaxial stretching device is used in the first step. 5. The coating film peeling method for a coated thermoplastic product according to claim 1, wherein an air jet is used in the second step. 6. The method for peeling a coating film from a coated thermoplastic product according to claim 1, wherein a wire wheel is used in the second step. 7. The method for removing a coating film from a coated thermoplastic plastic product according to claim 1, wherein a water jet is used in the second step. 8. A thermoplastic resin product (1) having a coating film (1b) obtained by coating a thermoplastic resin (1a) with a thermosetting plastic paint is carried, heated and stretched, and then the coating is carried out. A method for recycling a coated thermoplastic product, characterized in that the film (1b) is removed, and the thermoplastic (1a) is crushed, kneaded and melted, and molded. 9. A conveying means (2) for conveying a thermoplastic product (1) having a coating film (1b) obtained by coating a thermosetting plastic paint on a thermoplastic (1a),
Extending means (5) equipped with heating means arranged on the downstream side of the conveying means (2), coating film removing means (6), crushing means
(7), kneading and melting means (10) and molding means (14), the coated thermoplastic resin (1a) is the coating film (1
An apparatus for recycling a painted thermoplastic product, characterized in that it is configured such that after b) is removed, it is formed. 10. A stretching means provided with the heating means
10. The compression molding machine (5a) is used in (5).
An apparatus for recycling a coated thermoplastic product as described. 11. Stretching means provided with the heating means
10. The rolling roll (5b) is a roll (5).
An apparatus for recycling a coated thermoplastic product as described.