JP2014151581A - Resin coating film removal method and method of producing recycled polypropylene-based resin molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method enabling a resin coating film to be removed in the comparatively high removal ratio on both an aqueous resin coating film and a solvent-based resin coating film.SOLUTION: A resin coating film removal method is provided in which while a crushed material of a polypropylene-based resin member, having a polypropylene-based resin molded body and a resin coating film, and a coating film peeling agent including at least one kind of aromatic alcohol and glycol are contacted with each other under a temperature of 25-100°C, physical peeling treatment is applied to the crushed material by using a polishing stone having a specific gravity of 1.05-2.5 times of a specific gravity of the crushed material.

Description

  The present invention relates to a method for removing a resin coating film and a method for producing a recycled polypropylene resin molded body. More specifically, the present invention relates to a method for removing a resin coating film from a polypropylene resin member comprising a polypropylene resin molded article and a resin coating film, and to regenerate the polypropylene resin by removing the resin coating film by this method. And it is related with the method of manufacturing a polypropylene resin molding using this.

  Polypropylene resins are highly versatile, inexpensive, and excellent in various physical properties, and are used for automotive exterior members such as automotive bumpers. Various methods have been studied for the recycling of such polypropylene resin automotive exterior members, but the surface of the automotive exterior member is usually painted, and this resin coating is used. Since the film deteriorates the physical properties of the recycled polypropylene resin molded article, it has been a big problem in recycling the exterior member made of polypropylene resin for automobiles.

  Therefore, in order to suppress the deterioration of the physical properties of the recycled polypropylene resin molded product, a method of peeling the resin coating film by physical peeling treatment using an abrasive or chemical peeling treatment using a coating film peeling agent. Was being considered. However, in the physical peeling treatment, the resin coating film cannot be sufficiently peeled off, and the recycled polypropylene resin molded article still has the problem of deterioration in physical properties, and automobiles that require strength such as bumpers It cannot be used as an exterior member for automobiles, and has only been used in applications where strength is not so required. Also in chemical stripping treatment, conventional coating strippers contain halogen-based solvents, amine-based solvents, strong acids or strong alkalis. In addition, since the polypropylene-based resin molded product is also decomposed, the polypropylene-based resin molded product is deteriorated by the peeling treatment, and it is difficult to sufficiently suppress a decrease in physical properties of the recycled polypropylene-based resin molded product.

  On the other hand, in JP 2000-198953 A (Patent Document 1), a paint softener made of glycol ethers or acetates thereof and a coating film are brought into contact with each other and polished with an abrasive such as sandpaper, steel wool, or scrubbing. And the method of peeling a coating film is disclosed. Japanese Patent Laid-Open No. 2002-177786 (Patent Document 2) discloses a method of peeling a coating film by crushing the coating film with an abrasive and then applying a release agent to the surface of the crushed coating film. Yes.

JP 2000-198953 A JP 2002-177876 A

  However, in recent years, resin coatings that are difficult to scratch and resin coatings that are easily self-healing have been developed, and such resin coatings are more difficult to peel off. The coating film was likely to remain, and it was further difficult to sufficiently suppress the deterioration of the physical properties of the recycled polypropylene resin molded product.

  In addition, since conventional coating film release agents are roughly classified into water-based and solvent-based ones, either the aqueous resin coating film or the solvent-based resin coating film is not sufficiently peeled off and the coating film remains. There was a problem to do. For this reason, for example, when a polypropylene resin automobile exterior member is recycled, a polypropylene resin automobile exterior member includes a mixture of a water-based resin coating and a solvent-based resin coating. In many cases, it was necessary to classify in advance according to the type of the resin coating film.

  The present invention has been made in view of the above-described problems of the prior art, and is a method capable of removing a resin coating film at a relatively high removal rate for both an aqueous resin coating film and a solvent-based resin coating film. In addition, the polypropylene resin member can be regenerated without deteriorating the physical properties of the obtained polypropylene resin molded article, and the polypropylene resin member coated with the solvent-based paint and the polypropylene resin coated with the water-based paint It is an object of the present invention to provide a method capable of reproducing without separating the resin members even when they are mixed.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a specific gravity at a specific temperature in a coating film release agent containing at least one of an aromatic alcohol and a glycol ether. By applying a physical peeling treatment using the polishing stones possessed, the resin coating film is reliably removed in both the polypropylene resin member painted with the solvent-based paint and the polypropylene resin member painted with the water-based paint. In addition, the present inventors have found that the physical properties of the regenerated polypropylene resin molded product are sufficiently high, and have completed the present invention.

  That is, the method for removing a resin coating film of the present invention includes a crushed material of a polypropylene resin member (for example, an automotive exterior member) including a polypropylene resin molded body and a resin coating film, an aromatic alcohol, and a glycol ether. Using a polishing stone having a specific gravity of 1.05 to 2.5 times the specific gravity of the crushed material while contacting the coating film release agent containing at least one of the above at a temperature of 25 to 100 ° C. The pulverized material is subjected to physical peeling treatment.

  Moreover, the manufacturing method of the reproduction | regeneration polypropylene-type resin molding of this invention is a crushed material of a polypropylene-type resin member provided with a polypropylene-type resin molding and a resin coating film by the removal method of the resin coating film of this invention. It includes a step of removing the resin coating film and a step of producing a polypropylene resin molded body using the crushed material after the coating film is removed. The polypropylene resin molded body regenerated in this way can be used as an automotive exterior member.

  In this invention, it is preferable to contact both in the range from which the mass ratio of the said crushed material and the said peeling agent will be 1: 3 to 1:40. Moreover, when the said polypropylene resin member is further provided with a primer layer between the said resin coating film and the said polypropylene resin molded object, this primer layer is removed from the said crushed material with the said resin coating film. It is possible.

  According to the method for removing a resin coating film of the present invention, the resin coating film on the surface of the polypropylene resin molded body can be reliably removed. Moreover, by applying the method for removing a resin coating film according to the present invention, the resin coating film is removed from a polypropylene resin member provided with a polypropylene resin molding and a resin coating film. The polypropylene resin member can be reliably regenerated without deteriorating the physical properties. In addition, even when a polypropylene resin member painted with a solvent-based paint and a polypropylene resin member painted with a water-based paint are mixed, it is possible to regenerate them without sorting them.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

<Removal method of resin coating>
First, the removal method of the resin coating film of this invention is demonstrated. The method for removing a resin coating film according to the present invention includes a crushed material of a polypropylene resin member having a polypropylene resin molded body and a resin coating film, and a coating film peeling containing at least one of aromatic alcohol and glycol ether. In this method, the crushed material is subjected to a physical peeling treatment using a polishing stone having a specific gravity while contacting the agent with a specific temperature.

(Polypropylene resin member and its crushed material)
First, a polypropylene resin member capable of removing a resin coating film according to the present invention and a crushed material thereof will be described. A polypropylene resin member (hereinafter abbreviated as “PP resin member”) used in the present invention is formed on a polypropylene resin molded body (hereinafter abbreviated as “PP resin molded body”) and at least a part of the surface thereof. And a resin coating film. In such a PP resin member, a primer layer may be further formed between the resin coating film and the PP resin molded body. Examples of such PP resin members include automotive exterior members such as automotive bumpers. Further, such a PP resin member may be defective in the manufacturing process of various products, or may be removed from a discarded product. For example, examples of the PP resin member that is an exterior member for automobiles include those that are regarded as defective in the automobile manufacturing process and those that are removed from discarded automobiles. In addition, it is preferable that such a PP resin member is reproducible by the manufacturing method of the reproduction | regeneration polypropylene-type resin molding of this invention mentioned later.

  Examples of the PP resin molded body include an extrusion molded body, an injection molded body, a foam molded body, and the like of a polypropylene resin (hereinafter abbreviated as “PP resin”), and more specifically, automobiles such as automobile bumpers. What is used for the exterior member for a vehicle is mentioned. Moreover, rubber components such as ethylene-propylene copolymer rubber and ethylene-propylene-diene copolymer rubber may be blended with such a PP resin molded body. Furthermore, various additives such as fillers, pigments, antioxidants, ultraviolet absorbers, and heat stabilizers may be blended.

  Examples of the resin coating film include coating films made of organic resins such as acrylic urethane resin coating films, urethane resin coating films, acrylic resin coating films, polyester resin coating films, melamine resin coating films, and phenol resin coating films. More specifically, there may be mentioned those formed by paints used for painting automotive exterior members such as automotive bumpers. These resin coating films may be aqueous resin coating films formed from aqueous resins or solvent-based resin coating films formed from solvent-based resins. In the present invention, a PP resin member having either an aqueous or solvent-based resin coating can reliably remove the resin coating and obtain a recycled PP resin molded article having predetermined physical properties. Can do. The resin coating film may be a single layer or a multilayer of two or more layers. In particular, in the present invention, it is possible to remove a multilayer resin coating film in which an aqueous resin coating film and a solvent-based resin coating film are mixed. Although there is no restriction | limiting in particular as a film thickness of such a resin coating film, Usually, it is 5-50 micrometers. When the film thickness of the resin coating exceeds the upper limit, the resin coating may not be completely removed.

  Examples of the primer layer include those formed with various undercoat paints, and more specifically, those formed with an undercoat paint for automobile exterior members such as automobile bumpers. Such undercoat paints include water-based and solvent-based chlorinated polyolefin resin paints. In the present invention, regardless of whether the primer layer is aqueous or solvent-based, both the resin coating film can be reliably removed, and a recycled PP resin molded article having predetermined physical properties is obtained. Can do. Although there is no restriction | limiting in particular as thickness of such a primer layer, Usually, it is 5-20 micrometers. If the thickness of the primer layer exceeds the upper limit, the primer layer may not be completely removed.

  In this invention, after crushing such a PP resin member with a crusher etc., it is made to contact with a coating film peeling agent. The size of the crushed material is preferably 20 mm square to 150 mm square. When the size of the crushed material is less than the lower limit, the crushed material after peeling the coating film and the coating film release agent and the polishing stone may not be easily separated. In some cases, the contact area with the release agent decreases, and the resin coating film and the primer layer cannot be sufficiently removed.

(Film remover)
Next, the coating film release agent used when removing the resin coating film will be described. The coating film peeling agent according to the present invention contains at least one of aromatic alcohol and glycol ether. By using such a coating film release agent, it is possible to easily remove any aqueous or solvent-based resin coating film and primer layer from the crushed material without deteriorating the PP resin. As a result, even when an aqueous and solvent-based resin coating film and a primer layer are mixed, it is possible to remove them from the crushed material without separating them. Moreover, since the coating film release agent containing such a component does not easily remain inside the crushed material from which the resin coating film and the primer layer have been removed (PP resin molded body in a crushed state), the recycled PP described later is used. Odor generation is reduced in the molding step of the method for producing a resin molded body, and the working environment during the production of the recycled PP resin molded body is improved.

  As an aromatic alcohol used for the coating film peeling agent concerning this invention, the total number of carbon number is 7-10, and the alcohol provided with the hydrocarbon group containing an aromatic ring is preferable. As the hydrocarbon group containing an aromatic ring, a phenyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms, an aralkyl group which may be substituted with an alkyl group having 1 to 3 carbon atoms (benzyl group, Phenethyl group). Specific examples of such aromatic alcohols include benzyl alcohol, methylbenzyl alcohol, ethylbenzyl alcohol, phenethyl alcohol, and the like. Moreover, these may be used individually by 1 type, or may mix and use 2 or more types. Of these aromatic alcohols, benzyl alcohol is preferred because of its low cost and environmental hygiene.

  As glycol ether used for the coating film peeling agent concerning this invention, the glycol ether whose total number of carbon atoms is 3-10 is preferable. Specific examples of such glycol ethers include monoethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, 2- (hexyloxy) ethanol; 2 Monoalkylene glycol monoethers such as phenoxyethanol; monopropylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether; butylene glycol monomethyl ether, butylene glycol monoethyl ether Butylene glycol monopropy Monobutylene glycol monoalkyl ethers such as ether and butylene glycol monobutyl ether; diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether and diethylene glycol monobutyl ether; dipropylene glycol monomethyl ether and dipropylene glycol monoethyl Dipropylene glycol monoalkyl ether such as ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether; triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol Triethylene glycol monoalkyl ethers, such as glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol dialkyl ethers such as ethylene glycol diethyl ether. Moreover, these may be used individually by 1 type, or may mix and use 2 or more types. Among these glycol ethers, from the viewpoint of increasing the swelling property of the resin coating film and the primer layer, mono- or dialkylene glycol monoalkyl ethers having 3 to 10 carbon atoms are more preferable, and the total number of carbon atoms. Are more preferably mono- or diethylene glycol monoalkyl ethers of 3 to 10, ethylene glycol monobutyl ether and diethylene glycol monobutyl ether being particularly preferred, and ethylene glycol monobutyl ether being most preferred.

  In the coating film release agent according to the present invention, the upper limit of the content of glycol ether is not particularly limited and is 100% by mass or less, but the upper limit of the content of aromatic alcohol is preferably 80% by mass or less. It is more preferably at most 50% by mass, and further preferably at most 50% by mass. When the content of the aromatic alcohol exceeds the upper limit, the aromatic alcohol adheres to the surface of the PP resin molded product, and the coating film release agent tends to remain on the PP resin.

  In the coating film release agent according to the present invention, the total content of the aromatic alcohol and glycol ether is preferably 10% by mass or more, more preferably 30% by mass or more, and further preferably 50% by mass or more. If the total content of the aromatic alcohol and glycol ether is less than the lower limit, the resin coating film and the primer layer do not swell sufficiently, and the peelability of these tends to decrease. In addition, the upper limit of the total content of aromatic alcohol and glycol ether is 100% by mass or less. In addition, when the total content of aromatic alcohol and glycol ether is less than 100% by mass, other components contained in the coating film release agent include surfactants, water, glycol solvents other than glycol ethers, amines Examples thereof include compounds, alkali metal hydroxides, and organic acids.

  Among these coating film release agents, those containing at least one kind of aromatic alcohol and at least one kind of glycol ether from the viewpoint that the resin coating film and the primer layer are likely to swell and their peelability is improved. More preferred are those containing an alcohol having an aralkyl group and mono- or diethylene glycol monoalkyl ether having 3 to 10 carbon atoms, and particularly preferred are those containing benzyl alcohol and ethylene glycol monobutyl ether.

  In the coating film release agent containing such an aromatic alcohol and glycol ether, the content of the aromatic alcohol is preferably 5 to 80% by mass, and more preferably 5 to 50% by mass. Moreover, as content of glycol ether, 20-95 mass% is preferable, 20-85 mass% is more preferable, 30-60 mass% is especially preferable. When the content of the aromatic alcohol and glycol ether is within the above range, the resin coating film and the primer layer are likely to swell and the peelability of these tends to be improved. On the other hand, when the content of the aromatic alcohol exceeds the above upper limit, the aromatic alcohol adheres to the surface of the PP resin molded product, and the coating film release agent tends to remain on the PP resin.

  Moreover, it is preferable that the coating film peeling agent concerning this invention contains the nonionic surfactant. Thereby, it exists in the tendency for the peelability of a resin coating film and a primer layer to improve. Examples of such nonionic surfactants include alkylene oxide adducts of higher alcohols. Above all, from the viewpoint of improving the peelability of the resin coating film and the primer layer, C10-22 saturated or unsaturated. An alkylene oxide (2 to 4 carbon atoms) adduct of an aliphatic alcohol is preferable, and an ethylene oxide adduct of the aliphatic alcohol is more preferable. Moreover, as addition mole number of alkylene oxide, 4 mol or more is preferable and 6-20 mol is more preferable. As content of the nonionic surfactant in a coating film peeling agent, 0-5 mass% is preferable. Even when a nonionic surfactant in an amount exceeding the upper limit is contained, no further penetration effect is observed, and the peelability of the resin coating film and the primer layer tends to be difficult to improve. Moreover, in order to fully obtain the addition effect of a nonionic surfactant, it is preferable that content of a nonionic surfactant is 1 mass% or more. In addition, as an upper limit of content of a nonionic surfactant, 10 mass% or less is preferable, and 5 mass% or less is more preferable.

  Furthermore, it is preferable that the coating film remover contains water. Thereby, the danger of ignition of a coating film peeling agent can be reduced. In addition, when water is contained, when the resin coating and primer layer are physically peeled off by flowing crushed materials and grinding stones, the mobility and fluidity of crushed materials and grinding stones are increased. The shearing force or frictional force applied to the crushed material tends to increase, and the peelability of the resin coating film and primer layer tends to improve. As content of the water in a coating film peeling agent, 0-30 mass% is preferable. When the water content is within the above range, the swelling property of the resin coating film and primer layer by the aromatic alcohol and glycol ether in the paint remover and the improvement of the shearing force and frictional force of the resin coating film and primer layer are improved. The balance with the peelability is improved, and the peelability of the resin coating film and the primer layer tends to be improved. On the other hand, when the content of water exceeds the above upper limit, the risk of ignition of the coating film release agent decreases, but the peelability of the resin coating film and the primer layer tends to decrease.

  In the present invention, the pH is adjusted to 4 to 10 by adding an alkali component to the coating film release agent from the viewpoint of preventing corrosion of the machine used in the peeling treatment and suppressing physical property deterioration of the recycled PP resin molded body. It is preferable. Although there is no restriction | limiting in particular as said alkali component, Sodium hydroxide, potassium hydroxide, etc. are preferable.

(Coating removal method)
The method for removing a resin coating film according to the present invention is to perform a chemical peeling treatment by bringing a crushed material of a PP resin member comprising a PP resin molded body and a resin coating film into contact with the coating film release agent at a specific temperature. However, it is a method of subjecting the crushed material to physical peeling using a polishing stone having a specific gravity. Thereby, the resin coating film can be removed from the crushed material. Moreover, when the primer layer is formed between PP resin molding and a resin coating film, this primer layer can also be removed with a resin coating film. Furthermore, even if the resin coating film and the primer layer are either aqueous or solvent-based, they can be reliably removed.

  In the method for removing a resin coating film of the present invention, the crushed material and the coating film release agent are brought into contact at a temperature of 20 to 100 ° C. When the contact temperature between the crushed material and the coating film release agent is less than the lower limit, the coating film release agent does not sufficiently penetrate into the resin coating film and the primer layer. Even if the physical peeling treatment used is applied, the resin coating film and the primer layer are difficult to peel off. On the other hand, when the contact temperature is within the above range, the penetration of the coating film release agent into the resin coating film and the primer layer and the swelling of the resin coating film and the primer layer are promoted, and physical peeling treatment using a polishing stone is performed. The peelability by is improved. On the other hand, when the contact temperature exceeds the upper limit, a problem occurs in the working environment such as an odor becoming stronger due to volatilization of the solvent. In addition, the higher the contact temperature, the more the penetration of the coating film release agent into the resin coating film and the primer layer and the swelling of the resin coating film and the primer layer are further promoted, and the releasability by physical peeling treatment using a grinding stone. From the viewpoint of further improving the contact temperature, the contact temperature is preferably 40 to 100 ° C, more preferably 70 to 100 ° C. In addition, adjustment of such a contact temperature can be performed by adjusting the temperature of a coating film peeling agent. Adjustment of the temperature of the coating film release agent may be performed before the crushed material and the coating film release agent are brought into contact with each other, or may be performed simultaneously with the contact between the crushed material and the coating film peeling agent.

  Moreover, in the removal method of the resin coating film of this invention, as a method of making a crushed material and a coating film peeling agent contact, peeling processing is performed using a grinding stone, contacting a crushed material and a coating film peeling agent. There is no particular limitation as long as it can be used, but the crushed material is immersed in the coating film release agent from the viewpoint that it can be easily peeled by bringing the crushed material, the coating film peeling agent and the polishing stone into contact with each other. The method is preferred.

  The mass ratio (crushed product: coating stripping agent) when the crushed product and the coating film stripping agent are brought into contact is preferably 1: 3 to 1:40, and more preferably 1: 5 to 1:20. When the ratio of the coating film release agent is less than the lower limit, the crushed material and the coating film release agent are not sufficiently in contact with each other, so that the releasability of the resin coating film and the primer layer tends to be reduced. The processing amount of the crushed material per peeling treatment decreases, and the removal efficiency of the resin coating film and the primer layer and the production efficiency of the recycled PP resin molded product tend to decrease.

  The polishing stone used in the method for removing a resin coating film of the present invention is not particularly limited as to the material, but has a specific gravity of 1.05 to 2.5 times that of the crushed material. When the specific gravity of the grinding stone is less than the lower limit, the impact force is weakened, and it becomes difficult to sufficiently peel the resin coating film and the primer layer.On the other hand, when the upper limit is exceeded, the difference in specific gravity increases, It becomes a floating state on the polishing stone, and sufficient frictional force and collision force cannot be obtained, and it becomes difficult to sufficiently peel the resin coating film and the primer layer. Further, from the viewpoint of increasing the frictional force and collision force and improving the peelability of the resin coating film and the primer layer, the specific gravity of the grinding stone is preferably 1.1 to 2.0 times the specific gravity of the crushed material.

  The shape of the grinding stone is not particularly limited, but a cornered shape such as a triangular pyramid or a triangular prism is preferable. Although there is no restriction | limiting in particular as a magnitude | size of a grinding stone, The length of one side is 2 mm-15 mm is preferable.

  The amount of the grinding stone used is preferably 1: 2 to 1:50, more preferably 1: 4 to 1:30, in terms of the mass ratio of the crushed material to the grinding stone (crushed material: polishing stone). If the ratio of the grinding stone is less than the lower limit, the number of collisions between the crushed material and the grinding stone decreases, and the peelability of the resin coating film and the primer layer tends to be lowered. The processing amount of the crushed material is reduced, and the removal efficiency of the resin coating film and the primer layer and the production efficiency of the recycled PP resin molded product tend to decrease.

  In the method for removing a resin coating film according to the present invention, as a method of subjecting the crushed material to physical peeling treatment, the surface of the crushed material is hit, scratched, rubbed, or the like using the polishing stone. There is no particular limitation as long as it is a method capable of peeling the resin coating film and the primer layer by applying physical force such as shearing force and frictional force to the object. For example, the crushed material and the polishing stone are made to flow in the coating film peeling agent. Thus, a method of causing the crushed material and the grinding stone to collide with each other or rubbing them is preferable.

  As a specific method for subjecting the crushed material to a physical peeling treatment using a grinding stone while contacting the crushed material and the coating film release agent, the crushed material, the polishing stone, and the coating film peeling agent are used as a polishing tank. And barrel polishing in which the crushed material is polished by moving the polishing tank. As a motion mode of this barrel polishing, any of a vibration type, a rotary type, a flow type, and a centrifugal type may be used, but from the viewpoint of obtaining a high polishing ability, a flow type and a centrifugal type are preferable. Moreover, as another physical peeling processing method, the method of grind | pulverizing a crushed material by stirring the liquid mixture containing a crushed material, a grinding stone, and a coating film peeling agent, etc. are mentioned.

  The time for the peeling treatment in the present invention is appropriately set depending on the type of the coating remover and the temperature of the peeling treatment, but is preferably 5 to 60 minutes, more preferably 10 to 30 minutes. In the present invention, the chemical release treatment is performed while bringing the coating film release agent containing the above-described components into contact with the crushed material, and at the same time, the physical release treatment is performed using the polishing stone. Thus, the resin coating film and the primer layer can be reliably removed. On the other hand, when the peeling process is performed without using a coating film release agent or a grinding stone, it is difficult to sufficiently remove the resin coating film and the primer layer by such a short-time peeling process.

<Method for Producing Recycled Polypropylene Resin Molded Body>
Next, the manufacturing method of the reproduction | regeneration polypropylene resin molding of this invention is demonstrated. According to the method for producing a recycled polypropylene resin molded body of the present invention, a resin coating film is obtained from a crushed material of a polypropylene resin member comprising a polypropylene resin molded body and a resin coating film by the method for removing a resin coating film of the present invention. It is a method including a step of removing (coating film removing step) and a step of forming a polypropylene resin molded body using the crushed material after removing the coating film (molding step).

(Coating removal process)
The coating film removing step according to the present invention is a step of removing the resin coating film and the primer layer from the crushed material of the PP resin member by the resin coating film removing method of the present invention. According to the method for removing a resin coating film of the present invention, a crushed product from which the resin coating film and the primer layer have been reliably removed (that is, a pulverized PP resin molded product) can be obtained. In such a crushed material after removal of the coating film, it is needless to say that the remaining amount (area ratio) of the resin coating film and the primer layer is preferably 0%. The crushed material after removal of the coating film obtained in the step can be collected, washed with water and dried as necessary, and then used as it is in the molding step described below without being granulated. On the other hand, when a crushed product in which the residual amount (area ratio) of the resin coating film and the primer layer exceeds the upper limit is used as it is in the molding process without performing granulation, the physical properties of the regenerated PP resin molded product are deteriorated. There is a tendency.

  Thus, in the coating film removing step according to the present invention, since a PP resin molded body from which the resin coating film and the primer layer are surely removed is obtained, in order to suppress deterioration in physical properties of the PP resin molded body, The resin film and the primer layer remain and those that do not remain, the PP resin molded product is separated, or a granulation step is performed to impart uniform physical properties to the PP resin molded product. In the molding step, it is not necessary to mix the virgin resin and use the physical properties of the PP resin molded body.

(Molding process)
The molding process according to the present invention collects the crushed material after removal of the coating film obtained in the coating film removal step, and after washing and drying as necessary, from the crushed material after removal of the coating film This is a step of producing a PP resin molded body. In the present invention, the production method and production conditions of the PP resin molded product can be applied without changing (preferably as it is) the known production method and production conditions of the PP resin molded product. For example, the crushed material after removal of the coating film obtained in the coating film removal step is dried as necessary, and then heated to 200 to 220 ° C. to form various molding methods (for example, extrusion molding, injection molding, foam molding). ), A recycled PP resin molded product can be obtained.

  The thus-obtained recycled PP resin molded article has a sufficiently reduced decrease in the physical properties of the PP resin, and in particular has the same Charpy impact strength as a molded article made from a PP resin virgin material. It can be used as an automobile exterior member such as an automobile bumper.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Table 1 shows the types of the resin coating film and the primer layer (the types of the painted resin paint and the primer) of the PP resin automotive exterior member used in the examples and comparative examples.

Further, the coated surface of the crushed material after drying was visually observed, and the degree of peeling between the resin coating film and the primer layer was determined according to the following criteria.
<Peeling degree>
AA: The resin coating film and primer layer did not remain on the painted surface, and the remaining rate was 0%.
A: Although the resin coating film and the primer layer remained very slightly on the painted surface, the remaining rate was less than 1%.
B: Although the resin coating film and the primer layer remained very slightly on the painted surface, the remaining rate was less than 5%.
C: The resin coating film and the primer layer remained on the painted surface, and the remaining rate was 5% or more and less than 35%.
D: Resin coating film and primer layer remained on the painted surface, and the remaining rate was 35% or more and less than 50%.
E: The resin coating film and the primer layer remained on the painted surface, and the remaining rate was 50% or more and less than 75%.
F: The resin coating film and the primer layer remained on the painted surface, and the remaining rate was 75% or more and less than 100%.
G: Resin coating film and primer layer remained on the entire painted surface, and the remaining rate was 100%.

Furthermore, the surface of the crushed material after drying was observed visually and tactilely, and the surface residual degree of the coating film release agent was determined according to the following criteria.
<Surface residue of coating film release agent>
A: No oily residue was observed on the surface.
B: Some oily residue was present on the surface.

Example 1
The automobile exterior members 1 and 2 each having the resin coating film and the primer layer shown in Table 1 were cleaved to prepare crushed materials A-1 to A-2 (length 5 mm × width 5 mm × thickness 3 mm). A coating film remover was prepared by mixing 5 parts by mass of benzyl alcohol and 95 parts by mass of ethylene glycol monobutyl ether.

  7.5 kg of this coating film release agent, 1 kg of the crushed material A-1 or A-2 (specific gravity is 1.0) and 10 kg of plastic media (triangular pyramid grinding stone, length 15 mm, specific gravity 1.7) Then, it was put into a polishing tank of a fluid barrel polishing machine (manufactured by Shinto Kogyo Co., Ltd., model EVF-04), and the polishing tank was rotated at 80 ° C. and 300 rpm for 20 minutes to carry out peeling treatment. Thereafter, each crushed material was taken out, washed with water and dried at 100 ° C. for 3 hours. About the crushed materials A-1 and A-2 after drying, the peeling degree of the resin coating film and the primer layer and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Examples 2 to 4)
A coating film release agent was prepared in the same manner as in Example 1 except that the amounts of benzyl alcohol and ethylene glycol monobutyl ether were changed to the amounts shown in Table 2, a release treatment was performed, and each crushed product was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 5)
A coating film release agent was prepared by mixing 40 parts by mass of benzyl alcohol, 40 parts by mass of ethylene glycol monobutyl ether and 20 parts by mass of water. Except having used this coating film peeling agent, the peeling process was performed like Example 1, each crushed material was washed with water, and was dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 6)
A coating film release agent was prepared in the same manner as in Example 5 except that 15 parts by mass of water and 5 parts by mass of a 6-mol ethylene oxide adduct of decanol were mixed instead of 20 parts by mass of water. The product was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Examples 7 to 9)
Exfoliation treatment was performed in the same manner as in Example 5 except that the temperature during exfoliation treatment was changed to the temperature shown in Table 2, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 10)
A coating film release agent was prepared in the same manner as in Example 5 except that the amount of benzyl alcohol was changed to 30 parts by mass, the amount of ethylene glycol monobutyl ether was changed to 30 parts by mass, and the amount of water was changed to 40 parts by mass. Processing was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 11)
A coating film release agent was prepared in the same manner as in Example 5 except that 40 parts by mass of phenethyl alcohol was mixed in place of benzyl alcohol, a release treatment was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 12)
A coating film release agent was prepared in the same manner as in Example 5 except that 40 parts by mass of diethylene glycol monobutyl ether was mixed instead of ethylene glycol monobutyl ether, a peeling treatment was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 13)
Example except that 5 kg of plastic media (triangular pyramid-shaped grinding stone, length 15 mm) having a specific gravity of 1.1 was used instead of the plastic media having a specific gravity of 1.7, and the amount of the coating film remover was changed to 5 kg. In the same manner as in No. 5, a coating film release agent was prepared, a release treatment was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Example 14)
Example except that 25 kg of plastic media having a specific gravity of 2.3 (triangular pyramid-shaped grinding stone, length 15 mm) was used instead of the plastic media having a specific gravity of 1.7, and the amount of the coating film removing agent was changed to 18 kg. In the same manner as in No. 5, a coating film release agent was prepared, a release treatment was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 2.

(Comparative Example 1)
Exfoliation treatment was performed in the same manner as in Example 5 except that no grinding stone was used, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 3.

(Comparative Example 2)
A coating remover was prepared in the same manner as in Example 5 except that 30 kg of ceramic sintered media (triangular grinding stone, length 15 mm) having a specific gravity of 3.0 was used instead of plastic media having a specific gravity of 1.7. The crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 3.

(Comparative Example 3)
A coating remover was prepared in the same manner as in Example 5 except that 10 kg of a plastic medium (triangular pyramid-shaped grinding stone, length 15 mm) having a specific gravity of 0.9 was used instead of the plastic medium having a specific gravity of 1.7. Then, peeling treatment was performed, and each crushed material was washed with water and dried. About each crushed material after drying, the peeling degree of the resin coating film and the primer layer, and the surface residual degree of the coating film release agent were determined based on the above-mentioned criteria. The results are shown in Table 3.

  As is apparent from the results shown in Tables 2 to 3, the physical peeling treatment was performed using a polishing stone having a specific gravity in a coating film peeling agent containing at least one of aromatic alcohol and glycol ether. By performing, it was confirmed that the solvent-based resin coating film is sufficiently peeled off (Examples 1 to 14). Moreover, it was confirmed that the aqueous resin coating film can be sufficiently peeled by increasing the temperature during the peeling treatment (Examples 1 to 8 and 10 to 14).

  On the other hand, in the case where the physical release treatment was not performed in the coating film release agent (Comparative Example 1), the resin coating was compared with the case where the physical release treatment was performed (Examples 5 and 13 to 14). It was confirmed that the peelability of the film was inferior. Further, in the physical peeling treatment in the coating film release agent, when a grinding stone having a specific gravity of 3 times the specific gravity of the crushed material is used (Comparative Example 2), it has a specific gravity of 0.9 times. In the case of using a grinding stone (Comparative Example 3), the peelability of the resin coating film is inferior to that in the case of using a grinding stone having a predetermined specific gravity (Examples 5 and 13 to 14). It was confirmed that the peelability of the resin coating film was significantly reduced.

<Physical property evaluation of recycled PP resin molding>
The melt flow rate of the crushed material obtained after drying in Examples was measured by the following method. Moreover, using the crushed material after drying, injection molding was performed at a molten resin temperature of 200 ° C. and a mold temperature of 40 ° C., and a type A multi-purpose test piece was prepared according to ISO 3167. The parallel part of this multi-purpose test piece is cut out to produce a bar-type test piece (length 80 mm × width 10 mm × thickness 4 mm), and the physical properties of the recycled PP resin molded product are measured by the following method using the bar-type test piece. It was measured.

(Melt flow rate)
In accordance with the method described in ISO 1133, the melt flow rate of the recycled PP resin was measured under the conditions of load: 21.18 N and test temperature: 230 ° C.

(Tensile modulus)
In accordance with the method described in ISO 527-1, 2, a tensile test was performed under the conditions of a tensile speed: 50 mm / min, a distance between chucks: 115 mm, and a test environment: 23 ± 2 ° C. The elastic modulus was determined.

(Charpy impact strength)
A notch of type A having a radius of 0.25 mm was processed on the bar-type test piece so that the remaining width was 8.0 mm to prepare a notched test piece. Using this notched test piece, the Charpy impact strength of the recycled PP resin molding was measured at a test temperature of −30 ° C. or 23 ° C. by an edgewise test method in accordance with ISO 179-1,2.

(Brittle temperature)
The embrittlement temperature of the recycled PP resin molded product was measured according to ASTM D746-98.

(Load deflection temperature)
The deflection temperature of the recycled PP resin molded body at a bending stress of 1.8 MPa or 0.45 MPa was measured by the flatwise method in accordance with ISO 75-1 to 3-1.

(Rockwell hardness)
Based on the method described in ISO 2039-2, the Rockwell hardness of the recycled PP resin molding was measured.

  Table 4 shows various physical property values of the recycled PP resin recovered from the crushed product A-1 by removing the coating film in Example 5, Example 9, and Comparative Example 2, and the molded product thereof. Table 4 also shows various physical property values of the recycled PP resin molded body (unpeeled recycled product) produced from the crushed material A-1 from which the PP resin virgin material or resin coating film was not removed.

  As is apparent from the results shown in Table 4, the recycled PP resin obtained from the crushed material (Examples 5 and 9) from which the coating film was removed by the method according to the present invention (Examples 5 and 9) and the physical properties of the molded product were PP resin virgin material. And comparable to that molded body. On the other hand, in the case of physical peeling treatment using a grinding stone having a specific gravity 3 times the specific gravity of the crushed material in the coating film release agent (Comparative Example 2) and in the case of an unpeeled recycled product, Charpy Impact strength was low and embrittlement temperature was high. Moreover, in the non-peeled recycled product, the tensile modulus was also low.

  As described above, according to the method for removing a resin coating film of the present invention, the resin coating film on the surface of the polypropylene resin molded product can be reliably removed. Moreover, by applying the method for removing a resin coating film according to the present invention, the resin coating film is removed from a polypropylene resin member provided with a polypropylene resin molding and a resin coating film. The polypropylene resin member can be reliably regenerated without deteriorating the physical properties. In addition, even when a polypropylene resin member painted with a solvent-based paint and a polypropylene resin member painted with a water-based paint are mixed, it is possible to regenerate them without sorting them.

  Therefore, the method for producing a recycled polypropylene resin molded product of the present invention is such that the physical properties of the obtained polypropylene resin molded product satisfy the physical properties required for automotive exterior members such as automotive bumpers. This is useful as a method for reusing a polypropylene resin automotive exterior member such as an automotive bumper.

Claims (6)

  A crushed product of a polypropylene resin member comprising a polypropylene resin molded body and a resin coating film, and a coating film release agent containing at least one of aromatic alcohol and glycol ether, at a temperature of 25 to 100 ° C. A method of removing a resin coating film, comprising subjecting the crushed material to a physical peeling treatment using a polishing stone having a specific gravity of 1.05 to 2.5 times the specific gravity of the crushed material while contacting with the crushed material. The polypropylene resin member further comprises a primer layer between the resin coating film and the polypropylene resin molded body,
The method for removing a resin coating film according to claim 1, wherein the primer layer is removed together with the resin coating film from the crushed material.   The method for removing a resin coating film according to claim 1 or 2, wherein the mass ratio between the crushed material and the release agent is in a range of 1: 3 to 1:40.   The method for removing a resin coating film according to any one of claims 1 to 3, wherein the polypropylene resin member is an automobile exterior member. The process of removing a resin coating film from the crushed material of a polypropylene resin member provided with a polypropylene resin molded object and a resin coating film by the removal method of the resin coating film as described in any one of Claims 1-4. When,
A step of producing a polypropylene resin molded body using the crushed material after removing the coating film;
The manufacturing method of the reproduction | regeneration polypropylene-type resin molded object characterized by including.   6. The method for producing a recycled polypropylene resin molded article according to claim 5, wherein the recycled polypropylene resin molded article is an automobile exterior member.