JP4244776B2 - Method of recovering thermoplastic resin from resin molded article with coating film, thermoplastic resin composition, and thermoplastic resin molded article - Google Patents

Description

  The present invention is a method for recovering high-quality thermoplastic resin from a resin-molded article with a coating film while suppressing deterioration in physical properties and appearance, and using the recovered thermoplastic resin recovered by this method, impact resistance And a thermoplastic resin composition and a thermoplastic resin molded article excellent in appearance.

  Resin products that require high durability and appearance, such as automotive exterior parts, are made of thermoplastic resin molded products such as PP, ABS, modified PPE, and PA, and thermosetting resins such as urethane. A large-scale mass production is carried out.

  A product in which a thermosetting resin coating film is formed on such a thermoplastic resin substrate has a coating film when it is attempted to recover and reuse the thermoplastic resin from defective or used products generated in the painting process. Since it is not thermoplastic, the thermosetting resin of the coating film is dispersed and remains as a foreign substance in the recycled material. The mixing of the thermosetting resin coating film acts as a stress concentration point, and compared with a new thermoplastic resin that is not reused (hereinafter referred to as “virgin material”), impact strength and tensile strength. The physical properties such as the above may be deteriorated or the appearance may be deteriorated. Further, even if no appearance defect is seen in the state of the substrate, if the molded product is further coated, foreign matters may be raised on the surface and hinder smoothness, thereby causing an appearance defect.

  Therefore, when the resin molded product with a coating film is reused, a method of changing the coating component to a thermoplastic resin or peeling and separating the coating film can be considered. However, the former is not realistic because it is limited by the coating performance. Therefore, conventionally, a technique for effectively peeling and separating a coating film from a resin-molded article with a coating film and a technique for finely dispersing in a recovered resin have been studied.

  Conventionally, as a method of reusing a coated resin-molded product without removing the coating film, Japanese Patent Application Laid-Open No. 2002-86491 performs sandwich molding using a recycled material as a core layer and a virgin material as a skin layer. However, in this method, since the coating particle particles mixed in the recycled material made of the crushed material of the resin molded product with a coating film are large, the nozzle of the molding machine is clogged or the molded product It may cause poor appearance. Further, even if a resin molded product with a coating film is used after being finely pulverized, a decrease in physical properties is inevitable, and there is a possibility of causing problems in strength and reliability of the molded product.

  On the other hand, as a technique for peeling and removing a coating film from a resin-molded article with a coating film, JP-A-2001-353721, JP-A-2000-27193, JP-A-8-258044, A method of mechanically peeling by frictional force has been proposed. However, in this method, if the shear force at the time of peeling the coating film is low, the coating film does not peel sufficiently, and if the shearing force is increased, the coating film and the substrate are mixed in a finely pulverized state, and further charged with static electricity. Separation becomes difficult because they adhere to each other.

  In JP-A-8-290427, a mixed fine powder of a coating film and a base resin is stirred in a water bath to which a surfactant is added to remove charge and degas, and sort by the specific gravity difference. A method has been proposed. In this method, separation is possible if the base resin has a small specific gravity such as PP, but separation is difficult if the specific gravity is close to that of the coating resin component such as ABS. JP-A-6-91652 proposes removal of a coating film by sandblasting, but in this case, there is a possibility that a blasting abrasive may be embedded in the base resin, and there is a problem of new foreign matter contamination. Will occur.

  Furthermore, as a method for facilitating peeling of the crushed product by solvent immersion, JP-A-11-349726 discloses a method in which the crushed product is immersed in low boiling alcohol, dried and finely pulverized, and then the coating film is separated by wind. Proposed. However, in this method, since the solvent is a low-boiling point alcohol, there is a risk that handling is dangerous, and in the case of air separation, there is a drawback that the resin and the coating film cannot be sufficiently separated by charging of the finely pulverized product.

As another method, Japanese Patent Application Laid-Open No. 11-228730 proposes a method of separating a soluble resin and an insoluble resin using a separation solvent. However, in this method, a large amount of time is required for dissolving the resin. This equipment is necessary, and in order to distill off the solvent, a large amount of equipment and energy are required, which does not meet the original purpose of recycling.
JP 2002-86491 A JP 2001-40268 A Japanese Patent Laid-Open No. 2001-226639 Utility Model Registration No. 3070129 JP 2001-353721 A JP 2000-27193 A JP-A-8-258044 JP-A-8-290427 JP-A-6-91652 JP 11-349726 A JP-A-11-228730

  Thus, in the past, a method for easily and efficiently removing a thermosetting resin coating from a resin-molded article with a coating and recovering the thermoplastic resin of the base material in a high quality state has been proposed. None of these methods have drawbacks in recovery rate, processing efficiency, economy, workability, physical properties and appearance of the recovered thermoplastic resin.

  Therefore, the present invention is a high quality product that suppresses deterioration in physical properties and appearance from a resin molded product with a coating film in which a base material molded from a thermoplastic resin is coated with a paint mainly composed of a thermosetting resin. A method for easily and efficiently recovering a thermoplastic resin and a thermoplastic resin composition and a thermoplastic resin molded article excellent in impact resistance and appearance using the recovered thermoplastic resin recovered by this method The purpose is to provide.

The method for recovering a thermoplastic resin from a resin-molded article with a coating film according to the present invention is a molded article in which a base material molded from a thermoplastic resin is coated with a paint mainly composed of a thermosetting resin (hereinafter, “ In the method of recovering the thermoplastic resin of the substrate from the “resin-molded product with a coating film”), the resin-molded product with a coating film is brought into contact with a peeling solvent to swell or peel the coating film from the substrate. A swelling / peeling step and a water washing / separation step for separating the coating film from the substrate by washing the swelling / peeling-treated product with a coating film that is brought into contact with the peeling solvent in the swelling / peeling step The resin molded product is crushed to a size of 2 to 100 mm, the resin molded product with a coating film is brought into contact with the peeling solvent at a temperature of 10 to 80 ° C., and in the peeling step, the swelling / peeling treated product is It has a water inlet and a diffuser at the bottom of the tank, and discharges water at the top of the tank. Was charged into the flotation tank is a cylindrical water tub having, as well as washing the swelling and peeling treated product, is floated on the water surface in a state of carrying the bubble coating film piece was peeled from the substrate, the surface of the water A method for recovering a thermoplastic resin from a resin-molded article with a coating film, wherein the released coating film piece is further discharged with the bubbles generated on the water surface by a surfactant and discharged out of the floating separation tank, the ratio R / h of the diameter R and a height h of the bottom surface of該浮on separation tank is characterized in that from 0.5 to 20.

  That is, as a result of intensive investigations to solve the above problems, the present inventors swelled or peeled the coating film from the substrate using a peeling solvent, and then washed with water, so that the coating film was easily removed from the substrate. By being able to efficiently separate, in particular, by reducing the apparent specific gravity of the coating film by using bubbles at the time of washing with water, the coating film can be selectively levitated and easily separated from the substrate. The present inventors have found that the thermoplastic resin of the base material can be recovered without containing coating film components and thus causing no deterioration in physical properties and appearance of the virgin material.

In the present invention, the recovered thermoplastic resin is preferably a styrene resin and / or an olefin resin . Also, as the release solvent is preferably one having a boiling point as a main component 100 ° C. or more higher alcohols, esters, ethers, for example, a coating film with a resin molded article was put into a stirred vessel along with the release solvent 10 ~ By stirring at a temperature of 80 ° C., the coating film can be effectively swollen and peeled off.

  In the present invention, the swelling / peeling product is introduced into a floating separation tank having a water inlet and a diffuser at the bottom of the tank and a water outlet at the top of the tank. By washing with water and allowing the coating film to float, the peeled coating film and the substrate can be efficiently separated. That is, by using such a levitation separation tank, fine bubbles from the aeration means are attached to the coating film peeled from the substrate, and only the coating film is selectively levitated by the buoyancy. Can be separated. This levitation separation tank is preferably provided with a stirring means. In this case, the coating film is efficiently peeled and floated by collision or friction between the power of stirring and the swollen / peeled product introduced into the tank. Can do.

  The recovered thermoplastic resin is preferably supplied to an extruder equipped with a vacuum vent to be pelletized. By pelletizing, the thermoplastic resin can be easily reused. And if it is an extruder with a vacuum vent, since the solvent component and water | moisture content which are contained in collection | recovery thermoplastic resin can be deaerated in an extrusion process, a high quality collection | recovery thermoplastic resin pellet can be obtained.

  The thermoplastic resin composition of the present invention includes a recovered thermoplastic resin recovered by such a method of recovering a thermoplastic resin from a resin-molded article with a coating film of the present invention, and only from the recovered thermoplastic resin. It may be, and may contain other resin components and other additives. As the other resin component contained in the recovered thermoplastic resin composition of the present invention, a rubber reinforced styrene resin is particularly preferable.

  The thermoplastic resin molded article of the present invention is formed by molding the thermoplastic resin composition of the present invention, and has high performance and high quality thermoplasticity excellent in physical properties such as surface appearance and impact resistance. It is a resin molded product.

  According to the method for recovering a thermoplastic resin from a resin-molded article with a coating film according to the present invention, the physical properties of the thermoplastic resin as a base material can be determined from the inspection of the molded article and the thermoplastic resin with a coating film generated from waste. It is possible to easily and efficiently remove the coating film without reducing it, and to obtain a recovered thermoplastic resin that maintains the physical properties and appearance that can be reused as they are.

  Further, according to the thermoplastic resin composition and the thermoplastic resin molded product of the present invention, the recovered thermoplastic resin recovered in this way is used to form a thermoplastic resin excellent in physical properties such as surface appearance and impact resistance. Goods can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, the recovery method of the thermoplastic resin from the resin-molded article with a coating film of the present invention will be described.

  The resin-molded article with a coating film to be treated in the present invention is a molded article of a thermoplastic resin whose surface is coated with a paint mainly composed of a thermosetting resin such as urethane, and is used for automobile parts, electrical appliances, housing building materials. There are various products such as parts. For example, automotive parts related to radiator grills, fenders, door panels, bumpers, spoilers, mudguards, side moldings, wheel caps, instrument panels, door mirrors, front and tail lamps, etc. , Bike cowling and the like. In addition, in relation to electrical appliances, TVs, game machines, personal computers, mobile phones, etc. can be mentioned.In the case of residential building material parts, outdoor members include outer wall members, cable covers, etc. Examples include tables, costume cases, and pipes.

  There is no particular limitation on the thermoplastic resin composition that constitutes the base material of the resin molded product with a coating film. Examples of the thermoplastic resin include styrene resins such as ABS (acrylonitrile butadiene styrene) resin, PP (polypropylene), and the like. Polyolefin resin, polycarbonate resin, nylon resin, polyvinyl chloride resin, methacrylic resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene ether resin, etc., and even these single materials are alloy materials. In addition, a modified resin composition, or a mixture of various fillers may be used. Among these, it is particularly preferable in that the base material made of a molded product of a thermoplastic resin composition containing a styrene resin and / or an olefin resin is stable with little resin deterioration due to a process such as peeling, washing and drying. is there.

  There is no problem with a low specific gravity resin or foamed resin that floats on water as the thermoplastic resin, but if it is too light to float on the foam in the water washing / separation process described later, for example, it will be discharged together with the coating film from the floating separation tank. The specific gravity of the thermoplastic resin applied to the present invention is preferably 0.90 or more, more preferably 0.93 to 1.40, particularly preferably. It is the range of 1.00-1.20.

  On the other hand, the material of the coating film of the resin molded product with a coating film is not particularly limited, but generally used paints such as acrylic paints, epoxy paints, urethane paints, alkyd paints, melamine paints, Examples thereof include UV paints. Among these, preferred are thermosetting resins such as acrylic paints and urethane paints.

  Acrylic paints can be classified into acrylic lacquers, acrylic melamines, acrylic urethanes, acrylic epoxies, and the like, and include a type that evaporates the solvent to form a coating film and a type that crosslinks to form a cured coating film.

  As for the urethane-based paint, a two-component polyol-cured polyurethane type is mainly used, and other types include urethane lacquer and urethane polyol blended with acrylic polyol or polyester polyol and melamine cured.

  Although there is no restriction | limiting in particular also about the thickness of the coating film which consists of such a thermosetting resin, It is preferable from the surface of peeling efficiency that it is 1-200 micrometers normally, Preferably it is 5-150 micrometers in thickness.

  With regard to the paint, due to technological progress, the adhesion to the thermoplastic resin as the base material has been improved, but the method of the present invention swells the coating film formed on the base material surface from the base material. Since it is a method of peeling and separating the coating film from the substrate by using a peeling solvent for peeling, the type and thickness of the paint and the coating film are not limited at all, and other than the above Applicable.

  In such a resin-molded product with a coating film, a resin-molded product with a coating film that does not become a product is generated due to defective products during production or sampling quality inspection. In addition, there are defective products that are returned after shipment and waste materials that have finished their role in the market. The present invention is particularly effective in recovering and reusing a thermoplastic resin as a base material from such a defective product or a resin molded product with a waste coating film.

In the present invention, in the swelling / peeling step, the resin-molded article with a coating film is brought into contact with a peeling solvent to swell and peel the coating film. Prior to that, the coating film is easily swelled and peeled off. for, you crushed coated resin molded article in advance appropriate size. The degree of disruption, and the size of 2 to 100 mm, in particular 2 to 50 mm, especially preferably to 5 to 20 mm, by disrupting such a size, peeling of the coating film, the separation of the substrate Recovery is easy and efficient. When the degree of crushing is less than 2 mm, the coating film and the base material are not separated successfully when the coating film is separated by the flotation separation method described later, and the amount of the base material mixed into the coating film side is large. This is not preferable because the recovery rate of the thermoplastic resin is lowered. Further, if the degree of crushing exceeds 100 mm, the peeling solvent is difficult to permeate between the coating film and the base material, so that the peeling efficiency is lowered or the processing in the subsequent process is hindered. Absent.

  In the present invention, the size of the crushed piece of the resin-molded product with a coating film corresponds to the size of a mesh through which the crushed piece can pass, for example, a 2 mm × 2 mm mesh, but a smaller mesh size. The one that cannot pass is called 2 mm size.

  The resin-molded product with a coating can be crushed using a normal meshing-tooth crusher, and in order to make the size of the crushed pieces to a certain extent, it is uniform It is effective for processing.

  As the peeling solvent used in the present invention, a solvent mainly composed of higher alcohols, esters and ethers (hereinafter referred to as “high-boiling organic solvent”) having a boiling point of 100 ° C. or higher is used as a base material. It is preferable from the viewpoint of preventing excessive permeation, and is also preferable from the viewpoint of reducing loss due to evaporation during repeated use and reducing the risk of handling. Examples of higher alcohols, esters and ethers having a boiling point of 100 ° C. or higher include alcohols such as n-butanol, isopentyl alcohol and 1-decanol, esters such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, propylene glycol monomethyl Ethers such as ethers, alkylene glycol alkyl ethers, polyoxyalkylene alkyl ethers and the like can be mentioned, but are not limited thereto.

  The composition of the peeling solvent is preferably adjusted as appropriate according to the type of coating film, but commercially available products can also be used. For example, “HA-80” manufactured by Nippon Marcel Co., Ltd. is mainly composed of propylene glycol monomethyl ether. And effective as a stripping solvent used in the present invention.

  The release solvent may further contain a surfactant in order to increase the affinity (wetability) between the substrate and the coating film and the release solvent. As the surfactant, one or more of sodium alkyl ether sulfate ester, sodium α-olefin sulfonate, alkyl benzene sulfonate, alkyl glycoside and the like can be used. The peeling solvent may further contain a foam adjusting agent or an antifoaming agent.

  The coating film can be swollen and peeled by simply immersing the resin-molded article with a coating film, preferably its crushed pieces in such a peeling solvent, but the power of stirring, ultrasonic waves, bubbling, etc. It can be applied to swell the coating film or peel from the substrate, and further promote peeling.

The temperature condition when the resin molded product with a coating film, preferably the crushed pieces are brought into contact with the peeling solvent is preferably in the range of 10 to 80 ° C, more preferably in the range of 10 to 60 ° C, particularly preferably in the range of 20 to 50 ° C. It is. If this temperature is too low, the effect of the peeling solvent is not sufficiently exhibited, and it takes time for the coating film to swell or peel from the substrate, which is not preferable. On the other hand, if the temperature is too high, the effectiveness of the peeling solvent is exhibited, but the crushed pieces of the resin-molded product with a coating film are deformed, or the crushed pieces are peeled off from each other. The purity of the recovered thermoplastic resin obtained is undesirably reduced.

  The contact between the resin-molded product with a coating film and the peeling solvent is, in particular, by putting the crushed pieces of the resin-molded product with a coating film crushed into a suitable size as described above into a stirring tank having stirring blades, and It is preferable from the viewpoint of swelling / peeling efficiency of the coating to stir in a stripping solvent under conditions.

  The contact time in the swelling / peeling step is usually about 0.5 to 2 hours, although it varies depending on the treatment temperature, the presence or absence of auxiliary power such as stirring, the material and thickness of the coating film, and the type of stripping solvent used.

  In addition, although the peeling solvent used for the swelling / peeling treatment of the coating film decreases when it is attached to the resin-molded article with a coating film (or its peeling piece) and taken out of the system, the composition does not change. It can be used repeatedly for swelling and peeling treatment of the coating film.

  After the swelling / peeling treatment of the coating film in this manner, the swelling / peeling-treated product is then washed with water and separated from the coating film in the water washing / separation step.

  In the present invention, this water washing / separation step is performed using a floating separation tank as shown in FIG. 1, and simultaneously with water washing, the coating film is peeled off, and the separated coating film is separated from the substrate. Is preferred.

FIG. 1 is a schematic cross-sectional view showing a configuration of a flotation separation tank 1 suitable for carrying out the present invention, wherein 2 is an inlet for washing water, and 3 is an inlet for air. Although these inlets 2 and 3 are provided in the lower side wall part of the floating separation tank 1, they may be provided in the bottom part. A perforated plate 4 is provided at an intermediate height between the washing water introduction port 2 and the air introduction port 3 in the levitation separation tank 1 and introduced into the levitation separation tank 1 from the introduction port 3. Air rises in the floating separation tank 1 as fine bubbles in the perforated plate 4. A drainage outlet 5 is provided on the upper side wall of the levitation separation tank, and a mesh for preventing the floating coating pieces 12 from flowing out is provided at the opening of the outlet 5 into the levitation separation tank 1. The foreign matter outflow prevention plate 6 is provided. 7 is a stirrer and has a stirring blade 7A.

  In such a floating separation tank 1, washing water is introduced from the introduction port 2 and compressed air is introduced from the introduction port 3, and the swelled / peeled pieces 10 are put into the water in the vessel with stirring. Then, peeling of the coating film 11 adhering to and remaining on the crushed pieces 10 is promoted by the power of stirring and by collision or friction between the crushed pieces 10 and 10. And the apparent specific gravity of the coating-film piece 12 becomes small by the fine air bubbles 13 adhering to the coating-film piece 12 peeled from the crushing piece 10, and it floats in water.

  In this manner, the peeled coating film piece 12 is floated on the water surface in a state of being placed on the bubbles 13, and the coating film piece released on the water surface is further accompanied by bubbles generated on the water surface by the surfactant. It is recovered by discharging out of the levitation separation tank, and the coating film and the base material can be easily separated (in the present invention, a method of separating the coating film piece by air bubbles in this way). This is called “floating separation method”.)

Efficient separation of the coating film, for recovery, it is necessary to moderate heights for aquarium flotation tank 1, the ratio of the diameter and height of the bottom surface of the circular cylindrical aquarium (bottom diameter R / Height h) is set to 0.5 to 20, particularly preferably in the range of 0.5 to 10, particularly 0.5 to 5 .

  When separating the coating film by such a floating separation method, an overflow port may be provided in the floating separation tank so that the coating film to which bubbles are attached flows out of the tank together with the cleaning waste water.

If a surfactant is included in the stripping solvent used in the swelling / peeling process, bubbles are likely to be generated due to the foaming property of the surfactant in the levitation separation tank. in the bath with the addition of the aforementioned surfactant so as to promote the generation of bubbles.

  The coating film peeling step may be performed independently between the swelling / peeling step and the water washing / separation step. In this case, dividing the water tank for each process enables efficient continuous processing even in a small-scale plant.

  For example, a crushed piece of a resin-molded product with a coating film is placed in a stirring tank (first processing tank) containing a peeling solvent and stirred at a predetermined temperature for a predetermined time to swell or peel the coating film from the substrate. Then, the coating film is peeled by putting it into a stirring tank (second processing tank) containing water, and then the peeled coating film and the base material are floated and separated as shown in FIG. The coating film may be floated and separated into the processing tank), or a crushed piece of the resin-molded product with a coating film is charged into the stirring tank (first processing tank) containing the peeling solvent. The coating is swelled or peeled off from the substrate by stirring for a predetermined time at temperature, and then placed in a floating separation tank (second treatment tank) as shown in FIG. May be.

  The thermoplastic resin of the base material from which the coating film has been separated in this way is further washed with water and / or dehydrated, dried, and then supplied to an extruder or the like for pelletization (repellet). At this time, by using an extruder with a vacuum vent, it is possible to deaerate residual solvent components and moisture during extrusion. By using re-pellet, it can be used as a molding material as it is, and it is also convenient and preferable when dry blending a master pellet such as a foaming agent and a colorant used in normal processing. Furthermore, since it becomes easy to use as a raw material also when combining with other resins and additives, the recovered resin is preferably repellet.

  The recovered thermoplastic resin recovered from the resin-molded article with the coating film in this way can be reused as it is, and can be molded. The same kind of material or other thermoplastic resin, and various additions as necessary. It can also be reused by blending agents.

  Next, the thermoplastic resin composition of the present invention including the thermoplastic resin recovered by the method for recovering a thermoplastic resin from the resin-molded article with a coating film of the present invention will be described.

  The thermoplastic resin recovered from the resin-molded article with a coating film can be blended with the same type of resin or other resin as the base material of the resin-molded article with a coating film. When blended with other thermoplastic resins, the resins include ABS resin, ASA resin, AES resin, HIPS resin and other rubber-reinforced styrene resins, as well as AS resin, polystyrene resin, polycarbonate resin, nylon resin, methacrylic resin. Examples thereof include resins, polyvinyl chloride resins, polybutylene terephthalate resins, polyethylene terephthalate resins, and polyphenylene ethers. Further, a reinforcing agent such as MBS resin can be blended. Further, for the purpose of imparting compatibility during blending, the above resin modified with a compatibilizing agent or a functional group may be blended.

  These resins can be blended with the recovered thermoplastic resin singly or in combination of two or more, but it is particularly preferable to blend a rubber-reinforced styrene resin.

  The rubber-reinforced styrene resin will be described below.

  The rubber-reinforced styrene resin blended with the recovered thermoplastic resin of the present invention is one or more vinyls selected from aromatic vinyl monomers and vinyl cyanide monomers in the presence of a rubbery polymer. 5 to 100% by weight of a rubber-containing graft (co) polymer obtained by graft polymerization of a monomer, and one or more monomers selected from an aromatic vinyl monomer and a vinyl cyanide monomer It is preferably a rubber-reinforced styrene resin containing 95 to 0% by weight of a hard (co) polymer obtained by polymerizing the body.

  The rubbery polymer in the rubber-containing graft (co) polymer constituting the rubber-reinforced styrene resin includes conjugated dienes such as polybutadiene and copolymers of vinyl monomers copolymerizable with butadiene. Acrylic ester polymers such as polymers, acrylic ester polymers, copolymers of vinyl monomers copolymerizable with acrylic esters, ethylene-propylene or butene, preferably propylene-nonconjugated diene copolymers. Examples thereof include a polymer and a polyorganosiloxane polymer. Here, as the acrylic ester of the acrylic ester polymer, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, 2-ethylhexyl Examples of the diene contained in the ethylene-propylene-nonconjugated diene copolymer include dicyclopentadiene, 1,4-hexadiene, 1,4-heptadiene, 1,5, and the like. -Cyclooctadiene, 6-methyl-1,5-heptadiene, 11-ethyl-1,11-tridecadiene, 5-methylene-2-norbornene and the like. As the rubbery polymer, one of these can be used alone or as a composite rubber of two or more.

  Examples of the vinyl monomer to be graft-polymerized to such a rubbery polymer include an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth) acrylic ester used as necessary. , Other monomers capable of graft polymerization, such as maleimide compounds and unsaturated carboxylic acids.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, bromostyrene, and the like, and styrene and α-methylstyrene are particularly preferable. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is particularly preferable. Examples of other monomers include (meth) acrylic acid esters such as methacrylic acid esters or acrylic acid esters such as methyl methacrylate and methyl acrylate, and maleimide compounds include N-phenylmaleimide and N-cyclohexyl. Maleimide and the like can be mentioned, and examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid and fumaric acid. These can be used individually by 1 type or in mixture of 2 or more types, respectively.

  In the rubber-containing graft (co) polymer, the ratio of these monomer components is, by weight ratio, aromatic vinyl monomer: vinyl cyanide monomer: other monomer = 95-60: It is preferable to set it as 5-40: 0-50.

  The rubbery polymer content in such a rubber-containing graft (co) polymer is preferably 5 to 80% by weight. If this content is less than 5% by weight, the impact resistance of the resulting molded product will be inferior, and if it exceeds 80% by weight, the graft ratio will be lowered, resulting in inferior impact resistance.

  Furthermore, the rubber-reinforced styrene-based resin according to the present invention may be composed of a rubber-containing graft (co) polymer and a hard (co) polymer polymerized separately (for example, an AS resin).

  The hard (co) polymer is composed of an aromatic vinyl monomer and a vinyl cyanide monomer, and other copolymerizable unsaturated monomers used as necessary. Monomers similar to those exemplified as monomers to be grafted to the (co) polymer are used.

  In the hard (co) polymer, the ratio of these monomer components is, by weight, aromatic vinyl monomer: vinyl cyanide monomer: other monomer = 80 to 60:20 to 40: 0. It is preferable to set it to -60.

  Further, the weight average molecular weight of the hard (co) polymer is preferably 80,000 to 200,000. If this molecular weight is less than 80,000, the impact resistance is poor, and if it exceeds 200,000, the moldability deteriorates. .

  In the rubber-reinforced styrene resin, the ratio of the rubber-containing graft (co) polymer and the hard (co) polymer is 5 to 100% by weight of the rubber-containing graft (co) polymer and 95 to 0% by weight of the hard (co) polymer. The total amount is preferably 100% by weight. If there is a large amount of hard (co) polymer outside this range and a small amount of the rubber-containing graft (co) polymer, the impact resistance of the resulting molded product will be poor.

  The mixing ratio of the rubber-reinforced styrene resin and the recovered thermoplastic resin is not particularly limited, and a wide range of 0 to 99% by weight of the rubber-reinforced styrene resin and 100 to 1% by weight of the recovered thermoplastic resin can be adopted. In order to obtain characteristics suitable for other applications by blending rubber-reinforced styrene-based resins, for example, in order to reliably obtain effects such as modification of impact strength, mechanical properties, etc., recovered thermoplastic resins 5-60 The rubber-reinforced styrene-based resin is preferably 95 to 40% by weight with respect to% by weight.

  The thermoplastic resin composition containing the recovered thermoplastic resin of the present invention further includes known antioxidants, ultraviolet absorbers, lubricants, plasticizers, mold release agents, antistatic agents, colorants (pigments, dyes, etc.), Carbon fiber and glass fiber, talc, wollastonite, calcium carbonate, silica and other fillers, flame retardants (halogen flame retardants, phosphorus flame retardants, antimony compounds, etc.), anti-drip agents, antibacterial agents, anti-fungal agents, You may mix | blend 1 or more types of various additives, such as silicone oil and a coupling agent.

  There is no particular limitation on the pelletizing method when mixing these blending components and reusing the recovered thermoplastic resin composition of the present invention. For example, a melt-kneading method using an extruder, a Banbury mixer or the like is used. preferable.

  The thermoplastic resin composition of the present invention thus obtained can be molded into various molded products by injection molding, sheet extrusion, vacuum molding, pressure molding, profile extrusion molding, foam molding, blow molding and the like.

  The thermoplastic resin molded article of the present invention obtained by molding the thermoplastic resin composition of the present invention can be used for electric parts by blending flame retardants, inorganic fillers, and the like, including applications for vehicle parts and general equipment. It can also be suitably used for housings of electronic devices and electronic device parts, in particular, OA devices such as computers, printers, copiers and the like, and also housings of portable information devices such as mobile computers.

  Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples, Synthesis Examples, and Reference Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist. Absent.

[Recovery of thermoplastic resin from resin-molded articles with coating film]
The following two types of release solvents were used to recover the thermoplastic resin from the resin-molded article with a coating film.
Peeling solvent A: HA-80 (manufactured by Nippon Marcel Co., Ltd.)
Stripping solvent B: Propylene glycol monomethyl ether as the main component, alkyl ether
0.2 fold each of sodium tersulfate ester and fatty acid alkanolamide
Exfoliation solvent containing the amount%

Example 1
In a 50 liter stainless steel container equipped with a stirrer, 20 liters of peeling solvent and a resin-molded product with a coating film (radiator grille with a urethane-based coating film formed on the surface of an ABS base material) are crushed to about 20 mm square. 10 kg of the crushed pieces were charged, a band heater and a stirrer were attached, the temperature was adjusted to 40 ° C., and the mixture was stirred at 40 rpm for 60 minutes. By this operation, the coating film was swollen or peeled off from the substrate. Next, in order to collect the peeling solvent, the solution in the container was filtered using an 80 mesh stainless steel net.

The mixture of the base material and the coating film collected by filtration is charged into the floating separation tank shown in Fig. 1 (cylindrical water tank with a ratio of bottom diameter R / height h of 0.5 and holding 20 liters of water). Introduce and discharge 1 liter / min of washing water to wash, and separate the coating film peeled off at the same time as washing to blow compressed air (4 kg / cm ² ), generate bubbles, and rise to the water surface with the bubbles The operation of discharging the coated film out of the tank was performed for 30 minutes. Next, the water in the water tank was drained, the base material was taken out, and the base material was recovered using a centrifugal dehydrator.

Examples 2-8 and Comparative Examples 1-11
The same operation as in Example 1 was performed except that the resin-molded article with a coating film shown in Table 1 was a collection target and the conditions in each step were changed as shown in Table 1.

  However, in Comparative Examples 5 to 7, no compressed air was blown in the water washing / separation step. In Comparative Examples 8 and 9, in the water washing / separating step, the shape of the water tank was outside the preferred range of the present invention, and no washing water was introduced or discharged. In Comparative Example 10, only natural sedimentation was performed without introducing cleaning water and compressed air. In Comparative Example 11, only the crushing was performed without performing the swelling / peeling step and the water washing / separation step.

[Evaluation of recovered thermoplastic resin]
In Examples 1 to 8 and Comparative Examples 1 to 11, the water content on the surface of the obtained recovered thermoplastic resin was dried to calculate the recovery rate. In addition, the peeling and separation of the coating film, and the state of separation are visually observed. The coating film is sufficiently peeled and separated, and the coating film is not sufficiently peeled or the coating film is not sufficiently separated. In Table 2, these results are shown as x.

  Note that the volatile content in Table 2 is when about 50 g of the pre-dried recovered thermoplastic resin is placed in a heat-resistant glass container, dried at 130 ° C./2 hours with a mini dryer, and then the weight change before and after drying is calculated. This value indicates that the content of the peeling solvent is large.

  As is clear from Table 2, Examples 1 to 8 are excellent in the recovery rate and the peeling and separation of the coating film.

  On the other hand, in Comparative Example 1 in which the resin-molded product with a coating film was excessively crushed, the substrate was discharged together with the coating film in the separation step, so that the recovery rate was lowered and the coating film was not separated. It was enough. Moreover, since the temperature of the peeling process was high, the comparative example 4 contains many peeling solvents. In other comparative examples, the recovery rate and peeling or separation of the coating film were insufficient. In Comparative Examples 6 and 7, in the water washing / separation process, the balance between the supply and drainage of the cleaning water was inappropriate, and the coating film and the resin overflowed along with the overflow of the cleaning water, resulting in a significant decrease in yield.

  Next, the recovered thermoplastic resins obtained in Examples 1 to 8 and Comparative Examples 1 to 11 were re-pelleted (recovered thermoplastic resin; 100%) using a same-direction twin screw extruder with a vacuum vent mechanism. Various characteristics of the repellet thus prepared and obtained were evaluated by the following methods. The results are shown in Table 3.

  However, when Comparative Example 2 was repelletized, bridging occurred in the popper portion of the raw material supply port, and no repellet was obtained, so evaluation could not be performed.

In addition, as a test piece for evaluation, what was shape | molded at 220-260 degreeC with the 2 ounce injection molding machine (made by Toshiba Corp.) was used.
[Melt volume ^rate; MVR (cm 3 / 10min)] For ISO 1133 (measurement temperature and the load, ABS system 220 ℃ / 98N, PC / ABS system 230 ℃ / 98N, PP system 230 ° C. / 21.2 N )
[Charpy impact strength; IMP (KJ / m ² )] ISO 179 (normal temperature)
[Heat deformation temperature: HDT (° C.)] ISO 75 (Measurement load is 18.2 MPa for ABS and PC / ABS systems, 0.46 MPa for PP systems)
[Surface Appearance] The surface of the molded product was visually observed, and “Good” indicates that the appearance is good, “△” indicates that the appearance is small, and “X” indicates that there is a foreign matter and the like and the surface appearance is clearly poor.

  In Table 3, the result of having evaluated similarly about the unused article (virgin material) of the thermoplastic resin currently used for each use was written together as Reference Examples 1-3. The specific gravity of ABS was 1.07, PC / ABS was 1.12 and PP was 0.92.

  As is clear from Table 3, the recovered thermoplastic resins of Examples 1 to 8 are equivalent to or slightly inferior to Reference Examples 1 to 3 relating to the virgin material of each base material, but a balance between fluidity and impact strength. Excellent surface appearance. On the other hand, in Comparative Examples 1-11, impact resistance and surface appearance were inferior, and especially the surface appearance was greatly inferior by mixing of a coating film. Comparative Example 4 was an example in which silver was generated in the molded product and the surface appearance was deteriorated due to containing a large amount of solvent.

[Manufacture of molded thermoplastic resin products using recovered thermoplastic resin]
Examples 9-16, Comparative Examples 12-21
The recovered thermoplastic resin repellet recovered and repelletized in the above-mentioned Examples and Comparative Examples and the virgin materials of Reference Examples 1 to 3 are combined in the combinations shown in Table 4 and recovered thermoplastic resin: 30% by weight, virgin material The mixture was mixed at a ratio of 70% by weight, and pellets were produced in the same manner as in the production of the re-pellets described above, and various characteristics were evaluated in the same manner as in the evaluation method described above. Also, in order to evaluate the paintability, each molded product is painted with urethane and visually observed. The paint surface is smooth and the paintability is good. The case where the paintability was slightly inferior due to the appearance of a puff-like shape was rated as Δ, and the case where the paintability was poor because the majority of the surface of the coating was not smooth and a lot of puffiness was seen as x. These results are shown in Table 4.

  As is apparent from Table 4, those using the recovered thermoplastic resins of Examples 1 to 8 are excellent in physical properties, appearance and paintability, but those using the recovered thermoplastic resin of the comparative example are Surface appearance due to silver or paint film is inferior. In particular, foreign matter that appears to be a coating film emerges after coating, and the appearance is remarkably deteriorated.

[Manufacturing of a thermoplastic resin molded article containing a rubber-reinforced styrene resin and a recovered thermoplastic resin]
First, a rubber-reinforced styrene resin to be blended was synthesized according to the following synthesis example. In the following, “part” means “part by weight”.

Synthesis Example 1: Production of rubber-containing graft copolymer (a-1) An ABS copolymer was synthesized by the emulsion polymerization method with the following composition.
[Combination]
Styrene (ST) 35 parts Chloronitrile (AN) 15 parts Polybutadiene latex 50 parts (as solids)
Disproportionated potassium rosinate 1 part Potassium hydroxide 0.03 part Tertiary decyl mercaptan (t-DM) 0.1 part Cumene hydroperoxide 0.3 part Ferrous sulfate 0.007 part Sodium pyrophosphate 0.1 Part Crystalline glucose 0.3 part Distilled water 190 part

  Charge the autoclave with distilled water, disproportionated potassium rosinate, potassium hydroxide and polybutadiene latex, heat to 60 ° C, add ferrous sulfate, sodium pyrophosphate, and crystalline glucose, and keep it at 60 ° C. AN, t-DM and cumene hydroperoxide were continuously added over 2 hours, and then the temperature was raised to 70 ° C. and maintained for 1 hour to complete the reaction. An antioxidant was added to the ABS latex obtained by such a reaction, then coagulated with sulfuric acid, sufficiently washed with water, and dried to obtain an ABS graft copolymer (a-1).

Synthesis Example 2: Production of rubber-containing graft copolymer (a-2) Ethylene-propylene-nonconjugated diene copolymer rubber latex (ethylene: propylene: nonconjugated diene (5-ethylene-2-norbornene) 60 parts (solid) AES graft copolymer (a-2) was obtained in the same manner as in Synthesis Example 1, except that 12 parts of AN and 28 parts of ST were reacted.

Synthesis Example 3: Production of rubber-containing graft copolymer (a-3) In the same manner as Synthesis Example 1 except that 18 parts of AN and 42 parts of ST were reacted in the presence of 40 parts of polybutyl acrylate (as solids). As a result, an ASA graft copolymer (a-3) was obtained.

Synthesis Example 4: Production of Rigid Copolymer (b-1) 120 parts of water, 0.002 part of sodium alkylbenzenesulfonate, 0.5 part of polyvinyl alcohol, 0.3 part of azoisobutylnitrile, t in a nitrogen-substituted reactor -A monomer mixture consisting of 0.5 parts of DM, 35 parts of AN and 65 parts of ST was used, and after heating for 5 hours from the starting temperature of 60 ° C while adding part of ST sequentially, it was allowed to reach 120 ° C. Furthermore, after reacting at 120 ° C. for 4 hours, the polymer was taken out to obtain a hard copolymer (b-1) (weight average molecular weight 115,000).

The followings were used as other blend resins and additives.
Polycarbonate resin (c-1): Polycarbonate manufactured by Mitsubishi Engineering Plastics Co., Ltd.
-Bonate resin "S-3000" (viscosity average molecular weight (Mv): 21,000)
Flame retardant (d-1): “FP-500” (phosphate ester flame retardant) manufactured by Asahi Denka Kogyo Co., Ltd.
Inorganic filler (e-1): “MICRO ACE Micro Ace P-” manufactured by Nippon Talc Co., Ltd.
3 "(talc: average particle size (measurement method; centrifugal sedimentation method) 1.8 μm)

Examples 17-21, Comparative Examples 22-25
Using the re-pellet of the recovered thermoplastic resin recovered and re-pelletized in the above-described Examples and Comparative Examples, after mixing with the lubricant and antioxidant additive at the blending ratio shown in Table 5, at 220 to 260 ° C. The mixture was melt-mixed and pelletized with a twin-screw extruder (“TEX30α” manufactured by Nippon Steel). This resin pellet was molded at 220 to 260 ° C. with a 2 ounce injection molding machine (manufactured by Toshiba Corporation) to create the necessary test pieces, and the physical properties measured were the same as those shown in Table 4. Furthermore, the test results are shown in Table 5 with the addition of the following flexural modulus and flammability characteristics.
[Bending elastic modulus; MOD (MPa)] ISO 178
[Flammability] A 2 mm thick test piece was subjected to a combustion test according to UL94.

  As is clear from Table 5, Examples 17 to 21 are superior in impact strength and the like, particularly in surface appearance, as compared with Comparative Examples 22 to 25. Furthermore, by adding a flame retardant or a filler, it becomes possible to impart properties such as flame retardancy and rigidity, and a thermoplastic resin molded article that can be suitably used for other applications can be obtained.

  From the above results, the thermoplastic resin recovered by the present invention is excellent in impact strength and appearance, and has a characteristic that can be sufficiently used as it is, as is clear from comparison with the reference example. In addition, it is clear that blending with other resins can be used sufficiently for a wide range of applications.

  According to the present invention, it is possible to easily and efficiently recover a thermoplastic resin from a defective resin-molded product with a coating film or waste, and to effectively reuse it, reducing waste and The industrial utility of the present invention is extremely high in terms of maintaining the environment and effectively using resources.

It is typical sectional drawing which shows the structure of the flotation separation tank suitable for implementation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Levitation separation tank 4 Perforated plate 7 Stirrer 10 Fragmentation piece 11 Coating film 12 Coating film piece 13 Bubble

Claims (13)

From a molded product (hereinafter referred to as a “resin molded product with a coating film”) in which a base material molded from a thermoplastic resin is coated with a paint mainly composed of a thermosetting resin, the thermoplastic resin of the base material is changed. In the method of collecting,
A swelling / peeling step in which the resin-molded article with a coating film is brought into contact with a peeling solvent to swell or peel the coating film from the substrate;
The washing / separation step of washing the swelling / peeling-treated product with water to separate the coating film from the substrate,
In the swelling / peeling step, the resin molded product with a coating film to be brought into contact with the stripping solvent is crushed into a size of 2 to 100 mm,
The resin molded product with a coating film and the peeling solvent are contacted at a temperature of 10 to 80 ° C.,
In the peeling step, the swelling / peeling product is
It has a water inlet and a diffuser at the bottom of the tank, and is put into a floating separation tank that is a cylindrical water tank having a water outlet at the top of the tank .
The swelling / peeling-treated product is washed with water, and the coating film pieces peeled off from the base material are floated on the water surface in a state of being placed on the air bubbles. A method for recovering a thermoplastic resin from a resin-molded article with a coating film that is accompanied by bubbles generated above and is discharged out of the floating separation tank,
Recovering a thermoplastic resin from a coating film with a resin molded article and a ratio R / h of the diameter R and a height h of the bottom surface of該浮on separation tank is 0.5 to 20.   The method for recovering a thermoplastic resin from a resin-molded article with a coating film according to claim 1, wherein the thermoplastic resin is a styrene resin and / or an olefin resin having a specific gravity of 0.9 or more.   3. The coating film according to claim 1, wherein the peeling solvent contains, as a main component, one or more selected from the group consisting of higher alcohols, esters and ethers having a boiling point of 100 ° C. or higher. Method for recovering thermoplastic resin from resin-molded product with adhesive.   The temperature from which the resin molded product with a coating film and the peeling solvent are brought into contact is 10 to 60 ° C, and the heat from the resin molded product with a coating film according to any one of claims 1 to 3 A method for recovering the plastic resin.   The method for recovering a thermoplastic resin from a resin-molded article with a coating film according to any one of claims 1 to 4, wherein the floating separation tank includes a stirring means. The method for recovering a thermoplastic resin from a resin-molded article with a coating film according to any one of claims 1 to 5 , wherein the peeling solvent contains a surfactant. By stirring was charged into a stirred tank coating film coated resin molded article with the release solvent, any one of claims 1 to 6, characterized in that contacting the peeling solvent and the coating film with the resin molded article 1 The method for recovering a thermoplastic resin from the resin-molded article with a coating film according to the item. The recovered thermoplastic resin is supplied to an extruder with a vacuum vent to be pelletized, wherein the thermoplastic resin from the resin-molded article with a coating film according to any one of claims 1 to 7 is used. Collection method. Claims 1 to be recovered by the method according to any one of 8 thermoplastic resin (hereinafter, referred to as "recovered thermoplastic resin") thermoplastic resin composition which comprises a. The thermoplastic resin composition according to claim 9 , comprising a recovered thermoplastic resin. The thermoplastic resin composition according to claim 9 , comprising a recovered thermoplastic resin and other resin components and / or additives. The thermoplastic resin composition according to claim 1 1, characterized in that it comprises a rubber-reinforced styrene resin the recovered thermoplastic resin composition. It claims 9 to a thermoplastic resin molded article characterized by being obtained by molding the thermoplastic resin composition according to item 1 one of 1 2.

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