JP3200934B2 - Paint film peeling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for peeling off a coating film of a coated resin molded product.

[0002]

2. Description of the Related Art In order to recycle a coated resin molded product, it is necessary to peel off and remove the coating film on the surface of the molded product.

As a method for peeling and removing a coating film of a resin molded product, the following method is known.

[0004] 1) A method of peeling a coating film by immersing a resin molded product in a chlorine-based solvent such as dichloromethane; 2) Pulverizing the resin molded product without peeling the coating film and melting the resin portion in an extruder After that, a method of collecting insoluble matter (paint film, sand, and other contaminants) by filtration using a mesh screen provided at the outlet of the extruder to recover the resin; 3) Silica sand, ceramics, A method in which powder such as metal or synthetic resin or a liquid such as water is sprayed at a high pressure to physically scrape a coating film; 4) A resin molded product is immersed in a mixed liquid of various substances such as water / caustic soda. How to use a chemical reaction to decompose and peel off a coating film:

[0005]

However, the above methods 1) to 4) have the following problems, respectively.

[0006] Since the chlorine-based solvent used in the method 1) causes destruction of the ozone layer, there is an environmental problem. The screen used in the method 2) tends to be clogged in a short time, and it is necessary to frequently interrupt the operation of the apparatus in order to replace the screen. Therefore, high-speed processing cannot be continuously performed. The method 3) requires a long time for processing and is difficult to automate, and when performed manually, the working environment of the practitioner is poor and there is a hygienic problem. In the method 4), since the stripping solution used is a mixed solution, the stripping ability of the stripping solution that deteriorates with the progress of the chemical reaction is maintained, and the recovery, regeneration, and reuse of the solvent and reagent used as the stripping solution are performed. Is difficult.

The present invention is to solve the above-mentioned problems of the prior art.

[0008]

According to the present invention, a resin molded article having a coating film is placed in a container containing a lower alcohol heated to a temperature not higher than the boiling point and sealed.
An object of the present invention is to provide a method for removing a coating film, which comprises removing the coating film from the resin molded article.

The resin molded product from which the coating film can be peeled off by the method of the present invention is not particularly limited as long as it has a coating film. Specifically, the surface of the polyolefin resin molded product is acid-modified. Blend or chemically blend two components of acid-deformed chlorinated polyolefin-based undercoat / polyurethane-based paint on the surface of resin molded products and polyolefin-based resin molded products in which chlorinated polyolefin-based undercoat and polyurethane-based overcoat are applied in multiple layers. For example, a resin molded product to which a paint which is bonded to the surface is applied is exemplified. Further, a resin molded product to which melamine, alkyd, water-based paint, or the like is applied as a top coat can also be exemplified.

[0010] The resin molded article is not limited to those made of polyolefin resin. Further, the shape of the resin molded product is not limited, and examples thereof include interior and exterior products of automobiles such as an automobile resin bumper.

The above-mentioned resin molded product may be directly charged into a container containing a lower alcohol, but may be cut into an arbitrary size or crushed or pulverized according to the equipment to be used. No problem.

In the method of the present invention, the peeling speed of the coating film can be increased by crushing or pulverizing the resin molded product and feeding it. The size and shape of the crushed product when crushing the resin molded product are not particularly limited, but are preferably about 2 mm to 30 mm square, more preferably about 5 m.
Coarsely pulverize to about 10 to 10 mm square.

In the method of the present invention, a lower alcohol heated to a temperature below the boiling point is used as the stripping solution. The lower alcohol is a chain alcohol having 1 to 5 carbon atoms, examples of which include methanol, ethanol, propyl alcohol, butyl alcohol, amino alcohol and mixtures thereof, and methanol, ethanol and methanol. Mixtures of ethanol are preferred. Further, among these lower alcohols, ethanol has the lowest pollution to living organisms and the environment, and the use of ethanol enables low-pollutability and rapid removal of the coating film.

The lower alcohol is used in an amount of preferably 350 ml or more, more preferably 500 ml or more, based on 100 g of the resin molded product to be charged. A liquid such as an organic or inorganic solvent or a solid such as a salt may be mixed into the lower alcohol in order to improve the stripping ability, the washing ability and the like, or to change the specific gravity. However, when a mixture of multiple components is used as the stripping solution, the composition of the stripping solution after use changes. Therefore, if, for example, ethanol is used alone as the stripping solution, the composition of the stripping solution does not change, the stripping ability can be easily maintained, and the recovery operation can be performed only by separating the solid and condensing the solvent vapor at the time of drying the solid. become. Further, the frequency of the regenerating operation of the stripping solution can be reduced, and the reuse thereof can be facilitated.

The boiling point of the lower alcohol varies depending on the type of the lower alcohol and the external pressure. For example, when ethanol is used under normal pressure, the heating is performed to a temperature of 78.3 ° C. (the boiling point of ethanol at 1 atm) or lower.

As long as the temperature is lower than the boiling point, the heating temperature of the lower alcohol is not limited, but as the temperature is closer to the boiling point, an excellent peeling effect is exhibited. Therefore, when using ethanol, it is preferable to use 65 ° C. to 75 ° C. under normal pressure,
It is particularly preferably used by heating to 78 ° C. under normal pressure.

The means for heating the lower alcohol is optional. For example, if the container containing the lower alcohol is put in a water bath and the whole container is heated, the temperature of the lower alcohol can be kept constant for a long time.

In the method of the present invention, the resin molded product is sealed in a container containing a lower alcohol. The container used at this time is not particularly limited as long as it has a structure capable of sealing the vapor of the lower alcohol.

According to the method of the present invention, since the coating film is quickly peeled off, the method of the present invention is not limited to the batch processing, but can be performed continuously using a continuous processing apparatus.

[0020]

According to the method of the present invention, a resin molded product is sealed in a container containing a lower alcohol heated to a temperature below the boiling point, thereby swelling the coating film applied to the resin molded product. Increases the volume of the resin and causes a stress at the interface with the resin, which hardly changes in volume, whereby the coating film can be completely and rapidly peeled off without applying a strong external force.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings.

Using the following automobile bumpers (A) and (B), the following coating film peeling test was conducted. Bumper (A) Two layers of an acid-modified chlorinated polyolefin primer and a polyurethane-based topcoat applied to the surface of a polypropylene resin bumper (an ethylene propylene block copolymer containing 20% by weight of ethylene propylene rubber). Bumper (B) A resin in which an acid-modified chlorinated polyolefin primer / polyurethane-based paint is chemically bonded to the surface of a polypropylene-based resin bumper (an ethylene-propylene block copolymer containing 20% by weight of ethylene-propylene rubber).

First, arbitrary portions of the bumpers (A) and (B) were roughly pulverized to about 5 mm to 10 mm square.
Next, as shown in FIG. 1, about 80 ml of commercially available ethanol 1 (a first-class reagent manufactured by Wako Pure Chemical Industries, Ltd.) is poured into the peeling container 2, and heated to 78 ° C. using a water bath 4 equipped with a temperature controller 3. did.

Next, at the same time as opening the plug 6 of the input port 5 of the peeling container 2, the reflux cooling pipe 7 attached to the container 2 is opened.
A very small amount of air was exhausted from the upper part through an exhaust pipe 8 as shown by an arrow A to prevent ethanol vapor from leaking from the inlet 5. In this state, 20 g of the crushed bumpers (A) and (B) previously crushed were put into the peeling container 2 from the charging port 5, and the ethanol 1 in the container 2 was gently stirred by the stirring device 9.

Bumper (A) after stirring for about 70 seconds for the first time
After about 100 seconds, the peeling of the coating film of the pulverized material of the bumper (B) was completed.

From the ethanol in the container 2 containing the above-mentioned pulverized material, the free coating film / filtration / polyolefin resin was separated by a centrifugal separator utilizing a specific gravity difference, and then ethanol 1 was recovered. The ethanol 1 thus collected
Can be used for the next peeling operation.

In FIG. 1, reference numeral 10 denotes a stirrer attached to the tip of the stirrer, and 11 denotes a stopper for sealing the container. Arrow B indicates the flow of water for cooling the reflux cooler.

In the above experiment, the acid-modified chlorinated polyolefin-based primer applied to the bumpers (A) and (B) was swollen by the action of the heated ethanol 1 in the container 2 and was firmly strengthened by this. By swelling the thermosetting coating film (polyurethane coating) that is also bonded or chemically bonded to the surface, the volume of the entire coating film is increased, thereby causing stress at the interface between the coating film and the resin. Thus, the coating film can be peeled off without applying a strong external force.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the technical idea of the present invention.

For example, in the above embodiment, the bumpers (A) and (B) having different types of coating and different coating methods were put into the peeling container 2 together. However, in the present invention, resin of different grades is used. Even if a molded article is charged, there is no problem in peeling off the coating film if the treatment time is appropriately adjusted.
However, when it is desired to recycle high-quality resin, it is desirable to separate and feed the resin molded product to some extent.

In the above embodiment, the separation of the free coating film / filtration / polyolefin resin was carried out by utilizing the difference in specific gravity. However, this operation may be carried out by another separation method.

Further, in the above embodiment, ethanol was used alone as the stripping solution. However, in order to improve the stripping ability and cleaning ability of the stripping solution, or to change the specific gravity of the stripping solution, organic or organic ethanol was used. Various liquids such as inorganic solvents or solids such as salts may be used. Further, methanol can be used instead of ethanol.

[0033]

According to the method of the present invention, the coating film can be quickly peeled off, so that the resin molding having the coating film can be processed at a high speed and in large quantities, and the resin molding to be regenerated. Since the deterioration of the resin is small, a high-quality recycled resin can be obtained. In addition, since the peeling of the coating film is achieved by the swelling phenomenon, foreign matters rarely enter the lower alcohol due to the dissolution phenomenon, and the lower alcohol can be easily reused.

In the method of the present invention, since the peeling operation itself is simple, it is easy to automate the operation. Also, since the paint film can be completely removed and dirt such as sand can be removed at the same time, the primary cleaning step of the resin molded product recovered from the market can be omitted, and the mechanical property of the recycled resin molded product can be reduced. Factors that adversely affect properties and surface properties can be reliably removed. Further, since the coating film is peeled off in a closed container, the working environment of the practitioner is not contaminated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an apparatus for performing a coating film peeling test according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ethanol 2 Peeling container 3 Temperature controller 4 Water bath 5 Input port 6 Plug 7 Reflux cooling pipe 8 Exhaust pipe 9 Stirrer 10 Stirrer 11 Plug

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B05D 3/10 B05D 1/18 B05D 7/02 C08J 11/06

Claims (1)

(57) [Claims] 1. A resin molded article having a coating film is placed in a container containing a lower alcohol heated to a temperature not higher than the boiling point, and the container capable of sealing the vapor of the lower alcohol is hermetically closed. A coating film of the resin molded article, wherein the coating film is peeled off.