JP3553577B2 - Method of peeling and separating coating film of resin molded article - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for peeling and separating a coating film formed on a resin surface of a resin molded product. In particular, coatings applied to improve the weather resistance and decorative properties of resins such as polypropylene used as materials for automobile bumpers and grille parts are difficult to peel off from the resin, which hinders the recycling of the resin. Therefore, a method for easily peeling and separating such a coating film is provided.
[0002]
[Prior art]
Reusing the resin to which the coating film adheres involves the following problems: (1) particulate matter derived from the coating film having various colors is scattered in the resin, and the resin is recycled. (2) The surface of the recycled molded article is roughened by the particulate matter derived from the coating film, and the gloss is reduced. (3) The coating in the recycled molded article is deteriorated. The particulate matter derived from the film causes a notch effect and deteriorates the physical properties. (4) Recyclable materials cannot be used in parts where high physical properties (strength etc.) are required among automobile parts. is there. In particular, regarding physical properties, it is known that the impact resistance (Izod impact value) is reduced to about 50% and the tensile elongation at break is reduced to about 30% as compared with the virgin material.
[0003]
Then, the technique which peels a coating film from the surface of a resin molding is examined. For example, a melt filtration method, a blast method, a hydrolysis method, an organic solvent method, an alcohol / organic salt method and the like have been studied as a method of peeling a coating film.
[0004]
The melt filtration method is a method in which a resin having a coating film is heated and melted, and the resin in a liquid state and the coating film in a solid state are separated by filtration through a wire net. This method has a drawback of low efficiency because the wire mesh is easily clogged.
[0005]
The blasting method is a method in which the surface of a coating film is subjected to impact with powder or water injected at high speed and high pressure and simultaneously ground to remove and remove the coating film. This method has a drawback that the efficiency of peeling is low and that peeling is difficult if the surface of the object has irregularities.
[0006]
The hydrolysis method is a method in which a resin to which a coating film is attached is poured into a high-temperature acid or alkali aqueous solution, and the thermosetting resin coating film is hydrolyzed using an acid or alkali as a catalyst and removed. This method has drawbacks such as the necessity of an acid or alkali neutralization step. JP-A-5-185024 discloses a technique in which a coating film of a polyurethane-based paint is immersed in a heated saturated solution of sodium hydroxide in methanol to stir the whole.
[0007]
The organic solvent method is a method in which a coating film is peeled by swelling the coating film in an organic solvent to break an adhesive interface. This method requires a step of recovering the organic solvent, and also has a problem that the organic solvent remains in the recycled material.
[0008]
The alcohol / organic salt method is a method in which a coating film is put into a coating film decomposing agent composed of water, ethanol, and an organic salt, and is chemically decomposed and removed using organic salt ions as a catalyst. The target coating film is a melamine resin. This method has problems such as the necessity of a step of recovering the decomposing agent.
[0009]
[Problems to be solved by the invention]
As described above, the conventional technology has problems such as low efficiency, complicated processes, safety concerns of chemicals used, necessity of drainage treatment, high cost, and the like. Not in. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of peeling and separating a coating film which is more efficient and lower in cost than conventional techniques and does not require a complicated process.
[0010]
[Means for Solving the Problems]
The method for stripping and separating a coating film of a resin molded product according to claim 1 is to immerse the resin molded product having a coating film on a surface thereof in a liquid comprising a surfactant, and heat the resin molded product at 130 to 155 ° C. under normal pressure. The treatment is performed at a temperature.
According to a second aspect of the present invention, there is provided a method for peeling and separating a coating film of a resin molded body, wherein the liquid comprising the surfactant is recovered at a temperature of 50 ° C. or more after the heat treatment by the method of the first aspect. It is characterized by doing.
The method for stripping and separating a coating film of a resin molded product according to claim 3, wherein the resin molded product having a coating film on its surface is immersed in a liquid made of silicone oil, and heated at a normal pressure of 135 to 155 ° C. The process is characterized by
The method for stripping and separating a coating film of a resin molded product according to claim 4 is a method for forming a resin molded product having a coating film on a surface in a liquid composed of silicone oil containing 0.5% by weight or more of a surfactant. It is characterized by being immersed and treated at a heating temperature of 135 to 155 ° C. under normal pressure.
[0011]
The invention according to claim 5 is a method for peeling and separating a coating film of the resin molded product according to any one of claims 1 to 4, wherein the specific gravity of the liquid is equal to or less than the specific gravity of the resin molded product having the coating film. It is characterized by the specific gravity between the resin and the coating film.
The invention according to claim 6 is a method for peeling and separating a coating film of a resin molded article according to any one of claims 1 to 2 or claim 4, wherein the surfactant is a polyoxyalkylene alkyl ether. , Polyoxyalkylene alkylaryl ethers, and phosphoric acid esters or sulfates thereof, and polyoxyalkylene alkyl esters.
The invention according to claim 7 is a method for peeling and separating the coating film of the resin molded article according to any one of claims 1 to 6, wherein a stirring treatment is performed simultaneously with or after the heating treatment. and said that you do.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Examples of the material of the resin molded body used in the present invention include modified polypropylene and olefin-based thermoplastic elastomer. Among them, the modified polypropylene is, for example, a polypropylene obtained by modifying polypropylene with an ethylene propylene diene terpolymer (EPDM), and the olefin-based thermoplastic elastomer has a hard segment made of polyethylene or polypropylene and a soft segment made of EPDM. It is a plastic elastomer.
[0013]
Examples of the coating film include urethane paint. Specifically, an acid-modified chlorinated polyolefin-based undercoat and a polyurethane-based overcoat are separately applied to the surface of a polyolefin-based resin molded article in multiple layers. Examples thereof include those in which a coating material in which two components of a primer coating material / polyurethane-based coating material are blended or chemically bonded is applied. Further, melamine, alkyd, water-based paint or the like may be applied as a top coat. The thickness of the coating film is arbitrary, but is generally about 30 to 50 μm. For example, when urethane paint is applied to a bumper of an automobile, the thickness is about 30 μm.
[0014]
The liquid used in the present invention may be any liquid that can swell or dissolve the resin of the resin molded body without corroding the resin. Preferably, the liquid has a boiling point of 100 ° C. or higher at normal pressure and does not denature even at a high temperature of 180 ° C. Further, it is preferable that the liquid has a specific gravity between the resin and the coating film because the resin and the coating film are easily separated in the liquid. Examples of the liquid used in the present invention include a liquid containing a surfactant, an oil containing a surfactant, and a liquid containing an oil.
[0015]
As the liquid containing a surfactant, for example, when a coating film made of a urethane paint is peeled off, a phosphoric acid ester of polyoxyalkylene alkylphenyl ether or the like is preferably used.
[0016]
The phosphoric acid ester of polyoxyalkylene alkyl phenyl ether is, for example, a trade name of "Plysurf A210G" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and a mixture of polyoxyethylene alkyl ether and sodium sulfate of alkyl ether is: Sulfuric acid esters of polyoxyethylene lauryl ether are marketed under the trade name of "Natera" (manufactured by Lion Oil & Fat Co., Ltd.) under the trade name of "More" (manufactured by Kao Corporation). Note that the above “Natella” contains water and therefore cannot be used in a mixture with oil. Polyoxyethylene laurate (HLB: 9.5) is commercially available under the trade name “Nissan Nonion L-2”.
[0017]
As the oil containing a surfactant, for example, when a coating film made of a urethane paint is peeled, an oil containing a phosphoric acid ester of polyoxyalkylene alkylphenyl ether or the like is preferably used. Silicon oil or the like can be used as the oil. Silicone oil is preferred because it is flame retardant.
[0018]
As the silicone oil, a flash oil having a flash point of 300 ° C. or higher, a specific gravity of 0.960 to 0.970, a heat stability, and a nonvolatile oil is used. For example, “SRX-310” manufactured by Toray Industries, Inc. (flash point: 300 ° C. or higher, specific gravity (25 ° C.): 0.968, viscosity: 100 cSt, colorless and transparent), “YF-33” manufactured by Toshiba Corporation (flash) Point: 300 ° C. or higher, specific gravity (25 ° C.): 0.960, viscosity: 100 cSt, brownish brown, “KF-96” manufactured by Shin-Etsu Chemical Co., Ltd. (flash point: 300 ° C. or higher, specific gravity (25 ° C.): 0) Commercially available silicone oil such as 0.960 to 0.970, viscosity: 100 ± 5 cSt, or brownish brown. By mixing the surfactant in the oil, the oil adhering to the resin can be easily washed after the coating film is separated and separated.
[0019]
The concentration of the surfactant in the oil is preferably 0.5 to 100% by weight, more preferably 5 to 30% by weight. If the content is less than 0.5% by weight, it becomes difficult to remove oil adhering to the resin. As the liquid composed of oil, the same oil as the oil used in the oil containing a surfactant is used.
[0020]
According to the method of the present invention, first, a waste compact (for example, a bumper of an automobile) is collected, and this is roughly crushed or cut into a piece of 3 mm square or more. The molded article can be used as it is, but in that case, the coating film is cut in a mesh shape with a blade or a laser beam so as to be easily peeled off.
[0021]
In the present invention, a liquid is prepared, the molded body is completely immersed in the liquid, and treated at 105 to 180 ° C. for 3 minutes or more. When using an aqueous solution containing a surfactant, the heating temperature is preferably 120 to 160 ° C, more preferably 145 to 155 ° C, and the heating time is preferably 10 to 90 minutes, more preferably 15 to 40 minutes. It is. At the time of heating, it is necessary to pressurize with an autoclave or the like. When the aqueous solution is stirred, the processing time is preferably 10 to 30 minutes because the processing efficiency is increased.
[0022]
When using a liquid composed of a surfactant, the heating temperature is 30 to 180 ° C, preferably 50 to 160 ° C, more preferably 70 to 100 ° C, and the heating time is 1 minute or more, preferably 5 to 150 minutes. , More preferably 30 to 60 minutes. It can be heated at normal pressure, and no autoclave is required. It is not limited to the batch type, and continuous operation is possible. When the surfactant is agitated, the treatment efficiency is increased, so that the preferred treatment time is 5 to 60 minutes (5 minutes when plysurf is used, and 60 minutes when Nissan nonion is used).
[0023]
When using an oil containing a surfactant, the heating temperature is 30 ° C or higher, preferably 70 to 160 ° C, more preferably 140 to 155 ° C, and the heating time is 1 minute or longer, preferably 5 to 150 minutes. , More preferably 10 to 15 minutes. It can be heated at normal pressure, and no autoclave is required. It is not limited to the batch type, and continuous operation is possible. When the oil containing the surfactant is stirred, the processing efficiency is increased, so the preferable processing time is 5 to 15 minutes.
[0024]
When a liquid composed of oil is used, the heating temperature is 50 ° C or higher, preferably 70 to 160 ° C, more preferably 140 to 155 ° C, and the heating time is 1 minute or longer, preferably 1 to 150 minutes, more preferably. Is 10 to 15 minutes. It can be heated at normal pressure, and no autoclave is required. It is not limited to the batch type, and continuous operation is possible. When the oil is stirred, the processing time is preferably 5 to 15 minutes because the processing efficiency is increased.
[0025]
In order to stir the liquid, for example, a propeller having a diameter of about 5 to 10 cm is installed in the liquid in the processing tank having a capacity of 1 liter, and the propeller is rotated at 5 rpm or more, preferably 300 to 500 rpm. If the stirring is not performed, the portion of the molded article that has protruded from the liquid level may remain without being treated. By stirring, the surface of the resin molded article can be uniformly treated. Further, when stirred, there is an effect that the coarsely crushed resins rub against each other to accelerate the peeling of the coating film, and the coating film that has entered the unevenness of the resin is peeled off by the liquid flow or friction.
[0026]
The stirring may be performed after the heat treatment, but it is efficient to perform the stirring at the same time as the heat treatment. When a liquid with a specific gravity between the resin and the coating film is used, when left standing after the stirring process, the resin with a lower specific gravity than the liquid floats above the liquid, and the coating film with a higher specific gravity than the liquid sinks below the liquid. The two can be separated without any special operation.
[0027]
After natural cooling, the resin and the coating film are recovered. When a liquid containing a surfactant is used, if the temperature of the surfactant is too low during the resin recovery, the viscosity increases and it is difficult to recover the resin. Therefore, it is preferable to recover the resin at 50 ° C. or higher. The recovered resin is washed with water and then dried. The dried resin is melted, extruded and cut, and pelletized as a raw material for recycling.
[0028]
By the above operation, the coating film can be peeled almost 100%.
FIG. 1 shows the processing steps in the case of processing a cut resin product (A) and in the case of processing a pulverized product (B). As shown in (A), a resin molded body 5 composed of a coating film 3 and a resin 4 is immersed in a liquid (aqueous solution containing a surfactant) 6 in a container 2, which is then sealed with a lid 1 and autoclaved. And the like, the coating film 3 and the resin 4 are separated. (B) shows a step in the case of using a resin molded body 7 as a pulverized product. When the resin molded body 7 is treated in an autoclave or the like, the coating film 8 and the resin 9 are separated. When any of a surfactant, an oil containing a surfactant, and an oil is used as the liquid, it is not necessary to seal with the lid 1.
[0029]
FIG. 2 shows steps in the case of performing the treatment while stirring. In the liquid 14 in the container 11, the resin molded body 13 crushed is immersed, and the liquid 14 is stirred by the stirrer 12. When this is processed in an autoclave or the like, the resin molded body 13 is separated into the coating film 16 and the resin 15.
[0030]
【Example】
The following examples are all examples in which the resin of the resin molded product is a modified polypropylene (specific gravity 0.93) and the coating film is a urethane paint (specific gravity 1.8).
[0031]
Example 1
Example 1 is an example using a liquid containing a surfactant. In a 200 ml beaker, 50 ml of "Plysurf A210G" (manufactured by Daiichi Pharmaceutical Co., Ltd.) and 10 g of a crushed resin molded product were heated while stirring with a stirrer having a heating function. When the temperature rose to 130 ° C., a part of the coating film began to peel off, and completely peeled off at 145 ° C. When the stirring was stopped after peeling, the resin floated on the top and the coating film settled on the bottom of the beaker. The resin was recovered, washed with water, and dried.
[0032]
When the heating temperature reaches 158 ° C., the resin melts and envelops the once peeled coating film. Therefore, the heating temperature needs to be 100 to 158 ° C, preferably 130 to 155 ° C. Further, when collecting the resin from which the coating film has been peeled off, if the temperature of the surfactant is too low, the viscosity becomes high and it becomes difficult to collect the resin. Therefore, it is desirable to collect the resin at a temperature of 50 ° C. or higher.
[0033]
Example 2
The second embodiment is an example using a liquid made of silicon oil. In a 200 ml beaker, 50 ml of silicone oil (KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.) and 10 g of a pulverized resin molded product were placed and heated while stirring with a stirrer having a heating function. When the temperature was increased, a part of the coating film began to peel at 135 ° C., and completely peeled at 145 ° C. When 5 g of the pulverized product was further added while maintaining the temperature at 140 to 145 ° C, the coating film was peeled off within 1 minute. When the stirring was stopped, the resin floated to the top and the coating settled to the bottom of the beaker. The resin was recovered, and the attached silicone oil was washed with a surfactant and diluted ethanol. Note that when the heating temperature reaches 158 ° C., the resin melts and wraps around the peeled coating film, so care must be taken not to raise the temperature too much.
[0034]
Example 3
Example 3 is an example using an oil containing a surfactant. In a 200 ml beaker, put 50 ml of silicone oil (KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.), 10 ml of surfactant (Plysurf A210G, manufactured by Daiichi Pharmaceutical Co., Ltd.), and 10 g of a crushed resin molded product. The mixture was heated while stirring with a stirrer having a heating function. When the temperature was increased, a part of the coating film began to peel at 135 ° C., and completely peeled at 145 ° C. When 5 g of the pulverized product was further added while maintaining the temperature at 140 to 145 ° C, the coating film was peeled off within 1 minute. When the stirring was stopped, the resin floated to the top and the coating settled to the bottom of the beaker. The resin was recovered, and the attached silicone oil was washed with a surfactant and diluted ethanol. The removal of the oil was easier than in Example 2 using an oil containing no surfactant.
[0035]
【The invention's effect】
By the processing method of the present invention, the coating film is separated 100% and removed. Further, the liquid used in the present method is inexpensive, stable to heat and can be used repeatedly, and is non-volatile and safe for the human body. Further, the resin obtained by the treatment method of the present invention is not denatured by chemicals, and can be reused as a material having properties equivalent to that of a virgin material for parts requiring high properties. In addition, by stirring the liquid during the heat treatment, the efficiency of peeling can be increased, and the amount of surfactant used can be reduced and the processing time can be shortened.
[0036]
When an oil, a surfactant, or a mixture thereof is used as the liquid, a predetermined temperature can be reached at normal pressure, so that it is not necessary to use a device such as an autoclave and continuous operation is possible. In particular, silicon oil is stable at high temperatures up to 300 ° C. and can reach temperatures of 158 ° C. at normal pressure. Further, since silicone oil has a lower viscosity than a surfactant, the resin can be easily recovered even at a temperature of 20 ° C. or less.
[Brief description of the drawings]
FIG. 1 is a view showing a state before and after a resin molded body is separated into a resin and a coating film.
FIG. 2 is a view showing a liquid stirring step.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 lid 2 container 3 coating 4 resin 5 resin molding 6 liquid 7 resin molding 8 coating 9 resin 11 container 12 stirrer 13 resin molding 14 liquid 15 resin 16 coating

Claims (7)

A resin molded product having a coating film on its surface is immersed in a liquid comprising a surfactant, and is treated at a heating temperature of 130 to 155 ° C. under normal pressure. Method. 2. A method for separating and separating a coating film of a resin molded product, comprising recovering a resin and a coating film at a temperature of 50 ° C. or higher of the liquid comprising the surfactant after the heat treatment according to the method of claim 1. A method of peeling and separating a coating film of a resin molded product, comprising immersing a resin molded product having a coating film on a surface thereof in a liquid composed of silicone oil, and treating the coating at a heating temperature of 135 to 155 ° C. under normal pressure. . A resin molded product having a coating film on its surface is immersed in a liquid composed of silicone oil containing 0.5% by weight or more of a surfactant, and treated at a heating temperature of 135 to 155 ° C. at normal pressure. A method for peeling and separating a coating film of a resin molded article . The specific gravity of the liquid is the specific gravity between the resin and the coating film of the resin molded product having the coating film, and the peeling of the coating film of the resin molded product according to any one of claims 1 to 4, Separation method . The surfactant is at least one selected from polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl aryl ethers, and phosphates or sulfates thereof, and polyoxyalkylene alkyl esters. A method for peeling and separating a coating film of a resin molded product according to any one of claims 1 to 2 and claim 4 . The method for stripping and separating a coating film of a resin molded product according to any one of claims 1 to 6, wherein a stirring treatment is performed simultaneously with or after the heat treatment .

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