JP3412431B2 - Resin molded article coated with resin coating and method of regenerating the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded article provided with a coating film made of a resin coating material on the surface of a thermoplastic resin molded article and a method for recycling the same.

[0002]

2. Description of the Related Art Conventionally, many plastic (resin) moldings have been used for parts of automobiles and trucks, but as is well known, plastics do not decompose by microorganisms and generate harmful gas when burned. As a result, there are many problems in the processing. For this reason, in recent years, efforts have been made to recycle as much as possible without disposing of used plastic waste products after disposal.

[0003] For example, in the case of bumpers, which account for the largest proportion of automobile plastic molded products, after finely roughly crushing recovered products from scrapped vehicles or defective moldings, the coarsely crushed material as it is or virgin material. It can be effectively recycled by mixing it with the resin, heating and melting it, and then performing injection molding again.

However, in the case of using the product recovered from a scrap car as it is, the impact resistance of the plastic molded product can be improved by mixing the crushed paint film pieces into the plastic recycled by the paint film formed on the surface thereof.
Physical properties such as elongation and surface quality are significantly reduced, and the performance required as a bumper cannot be exhibited. Therefore, in order to effectively recycle such coated plastic parts,
Recently, for example, 1, a method of mechanically or chemically separating a plastic part and a coating film part by using an abrasive, a screen, a chemical agent or the like, and recovering only the plastic part and reusing it 2-273207, Japanese Utility Model Laid-Open No. 61-19
No. 6021 gazette, etc.) 2, Coarse crushing of a plastic material with a coating film, hydrolysis is performed to lower the molecular weight of the coating film adhering to it and disperse it in the matrix resin to reduce the influence of the coating film. Method (Japanese Patent Application 3-
No. 192431, Japanese Patent Application No. 3-357843, etc.) 3, Coarsely crushing a plastic material with a coating film, adding a coating film decomposing agent, and decomposing the coating film with this coating film decomposing agent to regenerate the coating film components. To reduce the influence of the coating film by dispersing in a base material resin (Japanese Patent Application Nos. 5-203580 and 5-9).
5400, etc.) have been proposed.

[0005]

However, the above-mentioned method has the following problems.

That is, of the methods shown in 1, the method using an abrasive is a method in which a soft abrasive or the like is sprayed on the surface of the coating film at a high speed (blasting) to remove the coating film. It is difficult to adjust the distance to the object, spray angle, air pressure, etc. The method using a screen is a method in which a coarsely crushed material of a coated plastic material is put into an extruder to melt only the plastic portion, and the coated film portion is separated by a screen provided at the exit of the extruder. But,
It is difficult to adjust the screen mesh. Further, the method using a chemical agent is one in which a coarsely pulverized material is immersed in a solution of the chemical agent to decompose and remove the coating film. However, the influence of the chemical agent deteriorates the physical properties of the plastic part. In addition, new problems such as waste liquid treatment occur.

Further, the method utilizing hydrolysis shown in 2 requires a large-scale facility for hydrolyzing the coating film, resulting in high recycling cost, which is economically unprofitable. .

Further, in the method of directly adding the film-decomposing agent shown in 3, the amount of the film-decomposing agent must be added in an amount larger than the actual amount of the film in order to cause a contact reaction with the film at the time of regeneration. There are many. Furthermore, if a paint film decomposer is directly added to the paint, it will be diluted with a diluting solvent in the case of spray coating, etc., and the amount that remains in the paint film will decrease, and it will come into direct contact with the paint resin component (color spreader). Therefore, the paint does not cure when the paint is baked and dried, and an uncured coating film is likely to be formed.

Therefore, the present invention has been devised in order to effectively solve such a problem, and an object thereof is to effectively remove a coating film piece after coarse crushing and to recycle a high-quality plastic product. The present invention provides a novel resin molded product that can be obtained at low cost and a method for recycling the same.

[0010]

In order to solve the above problems, the present invention provides a surface treatment film comprising a silane coupling agent or a titanium coupling agent which is insoluble in a coating solvent on the surface of coating film decomposed particles. To form a coating material for resin containing a powdery coating film decomposing agent formed on the surface of the thermoplastic resin molded article, and at a decomposition temperature of the surface treatment film of the coating film decomposing agent or lower. Paint and bake. As a result, the coating film decomposing agent is dispersed and fixed in the coating film without reacting with the coating solvent or coating resin (color-developing material).
A good coating film similar to the conventional one can be obtained.

Then, such a resin molded article is roughly crushed to form a resin material obtained by only the coarsely crushed material or a mixture of the coarsely crushed material and a virgin resin material. When kneaded by heating at the decomposition temperature of the coating film decomposing agent, the coating film decomposing agent melts and disperses and contacts and reacts with the coating film components,
The coating is decomposed to the molecular level and diffused into the thermoplastic resin.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment for carrying out the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an enlarged sectional view showing the vicinity of the surface of a resin molded product 1 according to the present invention.

As shown in the figure, the resin molded article 1 has a coating 3 formed by baking on the surface of a thermoplastic resin molded body 2 injection molded into an arbitrary shape. The coating film 3 is composed of an undercoat layer 4 directly applied to the surface of the resin molded body 2 and an overcoat layer 5 applied to the surface of the undercoat layer 4. Further, the overcoat layer 5 is the undercoat layer 4 6 which is directly applied to the surface of
And the clear 7 applied to the surface of the.

The thermoplastic resin molded body 2 is formed into a desired shape by an injection molding machine or the like by heating and melting a material such as a polyolefin-based or ABS-based thermoplastic resin. The coating film 3 is formed by baking and coating a chlorinated polyolefin resin, a polyester melanin resin or the like, which is a normal baking paint, at about 120 ° C.

Further, in the base 6 and the undercoat layer 4 forming the coating film 3, a powdery coating film decomposing agent 8 is present in a state of being uniformly dispersed and fixed.

As shown in FIG. 2, the coating film decomposing agent 8 is a silane coupling agent or a silane coupling agent which is insoluble in a coating solvent such as water or alcohol on the surface of the coating film decomposing particles 9 having a diameter of about several μm. The surface-treated film 10 made of a titanium coupling agent is formed by coating, and at the baking and drying temperature of the paint, that is, about 120 ° C., the surface-treated film 10 remains in the coating film 3 without being decomposed. 180 to 20
Under the temperature condition of 0 ° C, it is decomposed and the inside coating film decomposed particles 9
Are exposed and react with the paint resin component to decompose the coating film 3. The coating film decomposer 8 is a water-insoluble material such as benzotriazole, N-cyclohexyl-2-benzothiazole / sulfenamide, 2-di-n-butylamino-4,6-dimercapto-s. -Triazine, benzoguanamine, melamine, isomeramine,
2,4,6-trimercapto-s-triazine, N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine,
It can be obtained by immersing the decomposed particles 9 of coating film such as N, N'-di-β-naphthyl-p-phenylenediamine in a silane coupling agent or titanium coupling agent treatment liquid diluted with water and drying. it can.

Next, an example of a method for producing and reclaiming a resin molded product having such a structure will be described.

(Manufacturing method of resin molded product) First, the undercoat layer 4
Then, a prescribed amount of the above-mentioned coating film decomposing agent 8 is added to the coating material (stock solution) that constitutes the base 6 of the overcoat layer 5, and the mixture is stirred so as to be uniform. At this time, since the surface treatment film 10 of the coating film decomposing agent 8 is insoluble in the paint solvent, the coating decomposed particles 9 are in a state of being uniformly dispersed in the paint without affecting the paint resin or the like. ing.
Next, this paint is sprayed onto the surface of the resin molded body 2 which has been molded in a desired shape in advance, and the undercoat layer 4 and the overcoat layer 5 are baked and coated at about 120 ° C. for 30 minutes to have a thickness of several tens of μm. The coating film 3 is formed. At this time, the coating film decomposing agent 8 contained in the coating material constituting the base 6 of the undercoat layer 4 and the overcoat layer 5
Since the surface-treated film 10 is designed not to be melted and decomposed at the temperature at the time of this baking application, it is still fixed in a state of being uniformly dispersed in the paint. There is no adverse effect on 2.
Therefore, even if the coating film decomposing agent 8 of the present invention is contained in the coating material, a good coating film 3 similar to the case of using a normal coating material can be obtained. In addition, due to the aesthetic appearance of the coating film 3,
It is preferable not to add the coating film decomposer 8 to the clear 7 of the top coat layer 5.

(Method for Recycling Resin Molded Product) Next, in order to recycle the waste product of the resin molded product 1 having the coating film 3 as described above, first, this waste product is crushed by a crusher for about 1 to 10 m.
After roughly crushing into m squares, this coarsely crushed material is used as it is, or a resin material to which an appropriate amount of virgin resin material is added is mixed under a temperature condition of 160 to 200 ° C. in a twin-screw extruder,
Knead. Then, the film-decomposed particles 9 and the surface-treated film 10 which constitute the film-decomposing agent 8 contained in the film 3 are decomposed and melted by this heat (160 to 200 ° C.) and mechanical kneading. After contact with the paint resin component to cause a reaction to decompose the coating film 3, it is diffused into the thermoplastic resin material forming the thermoplastic resin molded body 2.

That is, when this coarsely pulverized material is kneaded by a twin-screw extruder at 160 to 200 ° C. to react the film-decomposing agent 8 with the coating resin component, the polyurethane-modified polyolefin constituting the undercoat layer 4 is weak. The urethane bond and the ether-bond of polyester-melamine that composes the base 6 and acrylic-melamine that composes the clear 7 are cleaved and cut, and melt-dispersed in a thermoplastic resin molding material such as a polyolefin-based or ABS-based coating film. It is possible to prevent the surface appearance of the recycled product from being deteriorated and the physical properties from being deteriorated due to the remaining pieces.

Thereafter, the thus kneaded product is directly regenerated as pellets or the like in a pelletizer, so that a high-quality regenerated product can be easily obtained without special treatment such as hydrolysis.

As described above, according to the present invention, the coating film formed on the surface of the thermoplastic molded article contains in advance a coating solvent or a coating film decomposing agent that does not melt and decompose during baking coating, and this is used during regeneration. Since the coating film decomposer is made to react with the coating film, it becomes possible to effectively remove the coating film pieces that adversely affect the recycled product. Moreover, in the method of the present invention, since the coating film pieces can be removed only by heating and kneading the coarsely pulverized material with an ordinary extruder, it becomes unnecessary to remove the coating film pieces at the time of regeneration as in the conventional case, the apparatus, etc. Can be significantly improved. In the present embodiment, the coating film decomposing agent 8 is mixed in the undercoat layer 4 together with the base 6, but it may be omitted in the undercoat layer 4 as long as it is mixed in the base 6.

[0024]

In summary, according to the present invention, it is possible to effectively remove a coating film piece that adversely affects the recycled product, so that a high-quality recycled plastic product can be easily obtained. In addition, it is possible to omit the most laborious and costly steps of peeling and separating the coating film, and it is possible to significantly reduce the recycling cost, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view showing an embodiment of a resin molded product according to the present invention.

FIG. 2 is an enlarged view showing part A (coating film decomposing agent) in FIG.

[Explanation of symbols]

1 Resin molded product 2 Thermoplastic resin molding 3 paint film 4 Undercoat layer 5 Overcoat layer 6 base 7 clear 8 Coating film decomposer 9 Paint film decomposed particles 10 Surface treatment film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C09D 201/00 C09D 201/00 (56) References JP-A-7-90107 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C09D 5 / 00,7 / 12,201 / 00 B29B 17/00 ZAB C08J 7 / 04,11 / 18

Claims (4)

(57) [Claims] 1. A coating material for resin, characterized in that it contains a powdery coating material decomposing agent in which a surface-treated film insoluble in a coating solvent is formed on the surface of the coating film decomposed particles. 2. The resin coating material according to claim 1, wherein the surface-treated film comprises a silane coupling agent or a titanium coupling agent. 3. The surface of the thermoplastic resin molded body according to claim 1.
A resin molded article comprising a coating film obtained by baking and coating the resin coating composition as described above at a decomposition temperature of the surface treatment film of the coating film decomposing agent or lower. 4. The resin molded article according to claim 3 is roughly crushed to form a resin material formed by only the coarsely crushed material or a mixture of the coarsely crushed material and a virgin resin material, and then the resin material. Was kneaded by heating at the decomposition temperature of the coating film decomposing agent, and the coating film decomposing agent was melted and dispersed to contact and react with the coating film components to decompose the coating film and diffuse it into the thermoplastic resin. And a method for recycling a resin molded product.