JP3139258B2 - Continuous reprocessing method of resin with coating film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating an inexpensive and non-polluting resin with a coating film. More specifically, using an extruder equipped with a pressure adjusting mechanism, the coating film contained in the molten resin is mixed with high-temperature / high-pressure water, a processing liquid which is an alcohol or a mixture of both, and / or a vapor thereof. When contacting and miniaturizing and uniformly dispersing in the molten resin, recover the vapor of water, alcohol or a mixture of both discharged to the outside of the extruder system through a pressure adjustment mechanism, and circulate and use it as a treatment liquid for resin with coating film The present invention relates to a method for continuously regenerating a resin with a coating film, which does not lower the physical properties of the regenerated resin and has high productivity and is inexpensive and harmless.

According to the method of the present invention, the paint to be hydrolyzed, particularly alkyd-melamine (or acrylic-melamine) resin-coated automotive bumper waste is crushed to a level that can be supplied to a twin-screw extruder. Is supplied to the twin-screw type extruder and brought into contact with a high-temperature and high-pressure treatment liquid and / or a vapor thereof to hydrolyze or alcoholyze the resin with a coating film,
By refining the coated resin to a level that is not harmful upon reuse, and by uniformly dispersing it in the molten resin,
That is, by simultaneously performing the hydrolysis or alcoholysis of the coating film and the uniform dispersion in the resin, the bumper,
It can be reused as a material for instrument panels and the like. Also,
The film decomposition products such as formaldehyde are distilled and separated from the vapor of the processing liquid containing the film decomposition products such as formaldehyde discharged to the outside of the extruder system through the pressure adjusting mechanism, and the film decomposition products are appropriately separated. Detoxification treatment in the treatment equipment, while collecting the treatment liquid from which the coating film decomposition products were removed,
By circulating and using the treatment liquid for the resin with a coating film in the extruder, it is possible to prevent the occurrence of a pollution problem and to improve the economical efficiency of the process for regenerating the resin with a coating film using the extruder.

[0003]

2. Description of the Related Art Disused bumpers, scrap cars, and scrap bumpers caused by repair or replacement during the manufacturing stage of automobiles are partially crushed and recycled as pallets for forklifts. In recent years, however, they have mainly been landfilled. However,
The development of recycling technology has become an issue due to restrictions on landfill sites, and one of the attempts is to study the reuse of recycled materials that are simply crushed, pelletized, and formed from painted bumpers as materials for bumpers, instrument panels, etc. It has been made.

However, in such a simple recycled material, a relatively large coating film piece (100 μm or more) is dispersed in the resin and adversely affects physical properties, particularly impact resistance (impact strength, embrittlement temperature) as foreign matter. The impact performance, which is the required performance of bumpers, instrument panels, etc., deteriorates. Also, if large coating pieces are present on the surface of the molded product, the appearance and quality are adversely affected. It was impossible to reuse it for quality. Therefore, in order to recycle the painted waste bumper to the original bumper, instrument panel, or the like, it was necessary to perform some treatment on the coating film, such as peeling of the coating film.

As a method for treating a coating film from a resin with a coating film,
The following mechanical stripping methods are generally known. Extrusion /
In the screen mesh method, a thermoplastic base resin is heated and melted, and an insoluble / infusible coating film is filtered / removed with an extruder filter, but a coating film having a size smaller than the mesh remains. Low removal rate of coating film. The specific gravity difference separation method is a method of separating a coating film by using a difference in specific gravity between polypropylene as a bumper base material and a coating film.However, since it is necessary to pulverize a bumper, an economical fine pulverization technique is used. Development is required. The shot blast method is a method in which organic or inorganic powder such as a suitable thermosetting resin is sprayed onto the bumper surface at high speed using high-pressure air to mechanically peel off the coating film. There are problems such as difficulty in peeling a coating film on a curved surface. The water jet method uses high-pressure water instead of the powder of the shot blast method, but this method has the same problem as the shot blast method. The vibration compression method is a unique method that uses a special device to compress and vibrate the paint bumper crushed product to separate the coating film.It has a small environmental load and sand and gravel adhering to the waste bumper. However, in order to further improve the appearance of the recycled bumper, there have been problems such as that the amount of the remaining coating film is still unsatisfactory.

Known chemical stripping methods such as a solvent swelling method, an alkaline solution boiling method, an acidic solution boiling method, and an organic salt-based solvent treatment method immerse the film in an acid or alkali solvent to decompose or physically remove the coating film. However, depending on the type of solvent, there are problems such as swelling or erosion of the base resin and deterioration of the quality of the recycled material. In addition, a solvent that does not damage the base resin takes a very long time to peel off, which is problematic in terms of productivity. Furthermore, there is a problem that the waste liquid treatment is considerably costly, such as a necessity of a neutralization step, and there is a concern that the organic solvent used in the treatment may affect the environment such as secondary pollution. .

[0007] As another method, WO93-1232 discloses a method of hydrolyzing and regenerating a resin with a coating film. That is, in this method, after the coated polypropylene bumper is pulverized and washed, it is placed in an autoclave at 110 to 240 ° C.
At a temperature of 1.5 to 35 kg / cm ² G, using water, alcohol or a mixture of both, or a vapor thereof, in the presence or absence of a catalyst such as an acid or an alkali. Hydrolysis and / or alcoholysis is performed for 240 minutes, and then the centrifugally dehydrated material is melt-kneaded with a twin-screw extruder and pelletized to obtain a recycled bumper material.

The disadvantages of this method are that the coating film undergoes hydrolysis and / or alcoholysis in an autoclave. (1) If the temperature is lower than 150 ° C., the hydrolysis and / or alcoholysis of the coating film takes time. On the contrary, if the temperature is higher than 160 ° C., the operating temperature is 150 to 160, for example, the polypropylene of the base resin is melted and fixed to form a block, and the subsequent centrifugal dehydration treatment becomes difficult.
(2) batch processing limited to a narrow range of ℃,
It takes time to raise and lower the temperature, which is inefficient. Therefore, the production efficiency of the recycled material is poor, and (3) the hydrolysis and / or alcoholysis of the coating film is static, and the action of the shearing force is small, so that there is no mechanical crushing of the coating film.

Further, a method for regenerating a coated resin by exposing the coated resin to water and / or steam in an extruder to hydrolyze the components of the coated film is disclosed in WO 93-1232.
However, it is difficult to maintain constant temperature and pressure conditions during the contact between the coating film and water and / or steam in an extruder, which is suggested in JP-A-5-228936 and JP-A-5-228936. There is a problem that there is a variation in the physical properties of the recycled resin to be obtained, and a stable continuous regeneration process cannot be performed. On the other hand, the exhaust port of the extruder emits waste steam of water and alcohol containing the decomposition products of the coating such as formaldehyde, which is a harmful substance.To prevent pollution and protect the global environment, Some kind of pollution control is required for waste steam. However, the above-mentioned patent publication does not disclose or suggest any pollution control treatment of these waste steams.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coating film which is simple in processing conditions and processing steps, has little physical property deterioration with respect to the original base resin, and is inexpensive and non-polluting. An object of the present invention is to provide a method for continuously and stably regenerating a resin.

[0011]

Means for Solving the Problems The present inventors contact a molten resin with a coating film in an extruder with high-temperature and high-pressure water and / or alcohol or a vapor thereof to continuously form the resin with a coating film. In order to develop an economical and pollution-free treatment method for efficient and stable regeneration, as a result of intensive studies, we devised cylinder heating devices, screw configurations, injection / exhaust systems, etc. The present invention has been found to be possible by using such an extruder, particularly a twin-screw extruder, and performing a distillation treatment of waste steam containing a coating film decomposition product discharged from an exhaust port of the extruder. Reached.

More specifically, the method of the present invention comprises (a) a resin supply port with a coating film, (b) a solid transport zone, (c) a melting zone, (d) a melt transport zone, and (e) a recycled resin discharge port (die). Providing at least one high pressure treatment liquid and / or its vapor inlet and at least one vent (vent) at the point of the cylinder which will be (c) melting zone and / or (d) melt transport zone; A pressure adjusting mechanism is provided in the middle of the two ports, and a portion on the upstream side of the injection port of the cylinder (the resin supply port with a coating film) and the pressure adjusting mechanism mounting port of the cylinder and the exhaust port. A sealing portion made of a molten resin for enclosing the processing liquid and / or its vapor that has been injected into a high-temperature and high-pressure state is formed at a location where
An extruder having a structure provided with a screw having a shape mainly performing kneading, particularly a twin-screw extruder is used, and in the extruder, a coating film contained in a molten resin is formed. Contacting with a high-temperature and high-pressure treatment liquid and / or its vapor to make the coating finer and uniformly disperse the coating in the molten resin, while decomposing the coating discharged to the outside of the extruder system through the pressure adjusting mechanism The product and the exhaust gas containing the vapor of the processing liquid are led to a distillation column, the coating film decomposition product is distilled off, and the processing liquid is circulated for use as a decomposition processing liquid for the resin with a coating film. Can be achieved.

Hereinafter, the method of the present invention will be described in detail. As described above, the method of the present invention basically includes the following two steps. One is in an extruder equipped with a pressure adjusting mechanism,
A resin with a coating film is brought into contact with a high-temperature and high-pressure treatment liquid and / or its vapor to decompose the coating film under a certain temperature and pressure condition, and finely disperse the coating film in a molten resin to form a recycled resin. This is the “resin treatment step with coating film”. The other is to recover the processing liquid from the exhaust gas discharged from the extruder system through the pressure adjusting mechanism and containing the decomposition product of the coating film and the vapor of the processing liquid, and recycle and reuse the processing liquid. This is the “treatment liquid recovery step”.

First, the "resin treatment step with a coating film" in the method of the present invention will be described in detail. In the method of the present invention, the coating film is decomposed / degraded upon contact with a high-temperature / high-pressure treatment liquid and / or its vapor, and is simultaneously mechanically pulverized, reduced in molecular weight and decomposed into fine particles,
It is dispersed in the base resin. Accordingly, the coating film component of the resin with a coating film used in the present invention is not particularly limited as long as it is finely divided by decomposition and deterioration upon contact with a high-temperature and high-pressure treatment liquid and / or its vapor. Although not required, an alkyd-melamine resin coating film or an acryl-melamine resin coating film capable of hydrolysis or alcoholysis is suitable.

However, in the method of the present invention, when the resin with a coating film is brought into contact with a high-temperature and high-pressure treatment liquid and / or its vapor, a coating film decomposition accelerator is appropriately brought into contact with the coating film. Can also. Therefore, as a coating film component of the resin with a coating film used in the present invention, besides the alkyd-melamine resin coating film or the acryl-melamine resin coating film capable of hydrolysis or alcoholysis, high-temperature / high-pressure processing solutions and And / or a heat-curable urethane-based paint composed of a polyisocyanate resin and a polyol resin, which is considered to be hardly hydrolyzed or subjected to alcoholysis even by contact with the vapor thereof, that is, a one-pack urethane paint or a two-pack urethane. System paints are also included.

Examples of the above-mentioned film decomposition accelerator include acids such as hydrochloric acid, phosphoric acid, acetic acid and oxalic acid, alkali metals such as sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide, and alkaline earth metals. Preferable examples include alkalis such as hydroxides, and salts such as sodium salts such as sodium phosphate, sodium hydrogen phosphate and sodium acetate, and ammonium salts such as ammonium phosphate and ammonium acetate. These acids, alkalis and salts are preferably supplied in the form of an aqueous solution or a powder, and catalyze the decomposition reaction of the coating film component by contact with a high-temperature processing solution and / or its vapor. .

The base resin used in the present invention is not particularly limited as long as it is a thermoplastic resin which is not easily decomposed under the conditions of contact between the coating film and a high-temperature / high-pressure processing liquid and / or its vapor. Although not intended, for example, polyphenylene oxide resins such as polypropylene, elastomer-modified polypropylene, polyolefins such as polyethylene, polyphenylene oxide, modified polyphenylene oxide (including styrene-modified polyphenylene ether),
ABS resin, AS resin, polyamide resin, polyester resin, polycarbonate resin, polyacetal resin and the like are preferable. Among these, a resin mainly composed of polyolefin, particularly polypropylene, which is a mainstream of automobile bumper materials, can be suitably mentioned.

In the method of the present invention, water and alcohol are used alone or as a mixture of the two as a treatment liquid for decomposing the coating film in contact with the resin with a coating film. As alcohol, methyl alcohol,
Preferable examples include hydrophilic alcohols such as ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, methyl cellosolve, and ethyl cellosolve. When a mixture of water and alcohol is used as the treatment liquid, the mixing ratio of both is water / alcohol = 100/0 to 0/100 by weight.
And is not particularly limited.

In the method of the present invention, the temperature at which the coated resin is brought into contact with the treatment liquid and / or its vapor in the extruder is selected depending on the type of the base resin and the coating used. It is usually sufficient that the melting point of the base resin is equal to or higher than the thermal degradation temperature, and within this range, a certain level suitable for hydrolysis or alcoholysis of the coating film or decomposition by a coating film decomposition accelerator is used. The temperature may be maintained. However, as long as the deterioration of the base resin does not occur, it is preferable that the temperature be as high as possible because the decomposition and miniaturization of the coating film are efficiently performed. The pressure at this time may be any pressure that can create a gas-liquid coexistence state in a contact zone between the resin with a coating film and the treatment liquid and / or its vapor in the extruder. Therefore, the temperature and pressure of the high-temperature and high-pressure treatment liquid and / or its vapor in the extruder used in the method of the present invention may vary depending on the type of the resin to be coated and the hydrolysis or alcoholysis of the coating. Alternatively, optimal conditions for decomposition by the coating film decomposition accelerator should be selected, and the conditions are not necessarily limited. However, in the case of a polypropylene bumper material coated with an alkyd-melamine resin, 160 to 250 ° C., 8 to 50 kg / cm ² G is appropriate, 180 to 235 ° C., 10 to 30 kg / cm ² G
Is more preferred.

By the way, the method of the present invention melts a crushed product of a resin with a coating film, and then treats a high-temperature and high-pressure treatment liquid and / or
Alternatively, the coating film is decomposed and refined by contacting with the vapor, and the finely divided coating film and the molten resin are kneaded, and the coating film is uniformly dispersed in the molten resin, and can be discharged out of the system. It is characterized by using an extruder having a function, such as an extruder such as a twin screw type extruder (meshing type / non-meshing type, co-rotating type / different-rotating type), special A single-screw extruder, a multi-screw extruder, a twin-screw reactor and the like are preferably exemplified. Among these, a twin-screw extruder of the twin-screw type and the same direction (or different direction) rotation is particularly preferable.

As described above, the twin-screw extruder particularly preferably used in the method of the present invention has a resin supply port with a coating film at one end and a recycle resin discharge port, that is, a die at the other end. A cylinder provided, a biaxial screw that is rotatably driven and meshes with each other in the cylinder, and a heat transfer device that heats or cools the cylinder from outside around the cylinder.

The screw in the cylinder comprises a solid transport zone, a melting zone (plasticizing zone) and a melt transport zone. The melt transport zone further comprises a high-temperature and high-pressure treatment liquid ( Or a contact zone with the processing liquid vapor, a devolatilization zone and a pressure increasing zone. The resin with a coating film forms a space formed by the cylinder and the screw in the cylinder by rotating the screw.
The solid transport zone, the melting zone, the contact zone, the devolatilization zone and the pressure rising zone are moved in this order.In order to lengthen the residence time of the resin containing the coating film particularly in the contact zone, the screw length is It is better to make it as long as possible. Usually, the length is preferably 20 to 60 times the cylinder diameter. In the case of a twin-screw reactor, a cylinder diameter of 5
A length of up to 20 times is preferred.

Each of the zones constituting the screw in the method of the present invention has the following functions. The solid transport zone is provided with a propulsion force of a biaxial screw that meshes with a crushed product of a coated resin such as a coating bumper waste material supplied from a coated resin supply port provided at an upstream end of the cylinder by rotational driving. Transfer to the next melting zone, ie, the plasticizing zone. The resin with a coating supplied to the solid transport zone can be supplied from a resin supply port with a coating provided at the upstream end of the cylinder, and a high-temperature, high-pressure processing liquid (or processing liquid) on the downstream side. It is desirable to use a crushed product previously crushed to 30 mm or less, preferably 10 mm or less with a crusher or the like so that the coating film can be efficiently decomposed and refined in the contact zone with (steam).

In the melting zone, the crushed product of the resin with a coating film is heated and melted by a kneading element (kneading disk) to be plasticized. Where this melting zone,
Alternatively, the cylinder near the upstream end of the point where it comes into contact with the high-temperature and high-pressure processing liquid (or processing liquid vapor), which is the most upstream part of the next melt transport zone, is provided with the high-pressure processing liquid and / or Alternatively, at least one high-temperature and high-pressure processing liquid vapor inlet is provided. And a point to be a melting zone or a point to be a contact zone with a high-temperature and high-pressure processing liquid (or processing liquid vapor), wherein the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid vapor injection port On the upstream side (on the side of the resin supply port with the coating film), a processing liquid and / or its vapor which have been brought into a high-temperature and high-pressure state in the contact zone are sealed in a space formed by the cylinder and the screw, Therefore, a filled area of the molten resin, that is, a seal portion is formed so that the vapor pressure can be maintained by overcoming the pressure of the high-temperature and high-pressure processing liquid (or the processing liquid vapor). The backflow of steam to the feed side can be prevented.

[0025] The high temperature, which is the most upstream part of the melt transport zone,
In a contact zone with a high-pressure processing liquid (or processing liquid vapor), a resin containing a coating film melted and plasticized in the melting zone is supplied from the injection port to a high-temperature high-pressure processing liquid and / or It is supplied from the injection port by the hydrolysis or alcoholysis reaction by contact with the vapor or in the presence of the above-mentioned film decomposition accelerator such as acid, alkali or salt, and is supplied from the injection port at high temperature and high pressure. By causing the decomposition reaction by the contact with the treated solution and / or the vapor thereof, the coating film in the molten resin is reduced in molecular weight and miniaturized. The degree of fineness of the coating film in the contact zone is determined by reusing the resin containing the coating film extruded from the recycled resin discharge port (die) provided at the end of the cylinder as a bumper material or the like. It is only necessary that the presence of the compound does not detrimentally affect physical properties and the like, and it is preferably 25 μm or less, and more preferably 15 μm or less.

In the method of the present invention, in order to efficiently perform the decomposition reaction of the coating film in the contact zone, the vapor is retained by the supplied high-pressure processing liquid and / or high-temperature and high-pressure processing liquid vapor. Area, ie process solution vapor / process solution-
It is necessary to provide a void based on the gas-liquid coexistence state of the molten resin, and for that purpose, as described above, the molten resin is formed in the space formed by the cylinder and the screw in the melting zone or the contact zone. While a filling area (sealing portion) is formed from the downstream side (recycled resin discharge port side) of a processing liquid vapor discharge hole described later provided in the contact zone and described later provided in the next devolatilization zone. A region (seal portion) filled with molten resin is also formed in a space defined by the cylinder and the screw on the upstream side (the resin supply port with a coating film) upstream of the exhaust port (vent). The length of the filled area of these molten resins should be such a length as to create a resin seal portion that resists the pressure of the void portion from the above-mentioned purpose, and the type of the resin with a coating film supplied. And the amount of high-pressure processing liquid (or high-temperature and high-pressure processing liquid vapor) injected, the temperature and pressure of the processing liquid (or processing liquid vapor) in the extruder, and the inner diameter of the extruder cylinder used. However, it is usually preferable that the diameter is 1 to 10 times the cylinder diameter.

The pressure of the processing liquid and / or its vapor supplied from the inlet of the processing liquid and / or its vapor is set in the contact zone at a high temperature / high pressure of the processing liquid and / or its vapor. In order to create a holding area, the pressure is preferably equal to or higher than the vapor pressure of the processing liquid in the contact zone. When the high-pressure processing liquid is injected from the inlet, the temperature of the processing liquid is not particularly limited, but a normal-temperature processing liquid is convenient for handling. Then, the high-pressure processing liquid injected into the extruder is heated in the extruder and brought into a high-temperature and high-pressure state suitable for the decomposition of the coating film as described above.

Further, in the present invention, in the region where the gap is formed in the contact zone, the coating film present inside the molten resin is positively brought into contact with the surface (between the resin and the gap) by the rotational driving of the screw. Boundary surface), and a surface renewal portion that increases the chance of contact with the coating film inside the resin by actively penetrating the processing liquid or the processing liquid vapor into the molten resin is provided. desirable.

Incidentally, the resin containing the coating film which has passed through the contact zone and has been miniaturized to the desired degree contains a processing liquid vapor or a processing liquid, and is directly used as a recycled resin discharge port of the cylinder described later. When the resin is extruded from a die nozzle provided in the (die), the resin may be in a foamed state, and the strand may not be drawn. Therefore, the extruder used in the method of the present invention is provided with a devolatilization zone on the downstream side of the contact zone of the melt transport zone, and at least one cylinder is provided at a location where the zone is formed. An exhaust port (vent) is provided. Then, the treatment liquid component in the resin is removed by discharging the gas into the atmosphere from the exhaust port (vent) or by performing a vacuum vent with a known vacuum device such as a Nash pump.

However, since only the volatile components such as the processing liquid components can be removed by air release from the exhaust port or vacuum venting, the impurities are discharged together with the resin to discharge the impurities together with the resin for the purpose of positively discharging the impurities. It can be discharged in a foamed state from a die nozzle portion of an outlet (die) and then washed with hot water or the like. Therefore, the devolatilization zone is not absolutely required as the screw configuration of the extruder used in the method of the present invention.

The final stage of the melt transport zone is the pressurization zone. In the pressure rising zone, a die nozzle portion is provided at the regenerated resin discharge port (die) at the end thereof, and the molten resin devolatilized in the devolatilization zone, or
Depending on the purpose, the molten resin containing the processing liquid component which has not been devolatilized is compressed to overcome the resistance of the die nozzle portion and apply a pressure sufficient to pass through the nozzle hole, thereby providing the nozzle hole. The resin is further extruded and discharged from the recycled resin discharge port (die) in the form of a strand or in a foamed state. Therefore, the pressure in the pressure increasing zone is preferably about ^{2 to} 150 kg / cm ² G, though it varies depending on the type and processing amount of the resin with a coating film supplied to the extruder.

As described above, the resin with a coating film supplied from the resin supply port with the coating film into the extruder is driven by the rotation of the screw to move the melt transport zone, that is, the contact zone, the devolatilizing zone, While sequentially moving through the pressurizing zone, the coating film is refined to a level usable as a recycled material, and the coating film is kneaded and included in the molten resin, so that the coating film is contained in the molten resin. It is uniformly finely dispersed. The recycled molten resin discharged from the recycled resin discharge port (die) in the form of a strand is not particularly limited, but is preferably further cooled in a water-cooled water tank, cut with a pelletizer, and pelletized. As these water-cooled water tanks and pelletizers, those commonly used are sufficient. In the method of the present invention, it is possible to cut the recycled molten resin discharged from the recycled resin discharge port (die) by a method such as hot cutting or cutting with an underwater cutter. Pelletization of the reclaimed molten resin is not essential, and is discharged in a strand form from the reclaimed resin discharge port (die) by various molding methods such as injection molding, extrusion molding, blow molding, transfer molding, and press molding. It is also possible to directly mold the final product from the recycled molten resin.

Next, among the operating parameters of the extruder in the method of the present invention, in particular, the twin-screw extruder having the above-mentioned screw configuration, the main parameters will be described. The degree of decomposition and fineness of the coating film is determined by the temperature, pressure and residence time of the resin containing the coating film in the contact zone, and exposing the coating film inside the resin to the surface where the processing liquid (or processing liquid vapor) intervenes. Or, conversely, it is determined by the ability to permeate and disperse the processing liquid (or processing liquid vapor) inside the resin and contact the coating film inside the resin. Not only the reaction conditions (temperature and pressure), but also the processing amount of the resin with the coating, the supply of the processing liquid and / or its vapor, the supply of the coating decomposition accelerator, the screw configuration, the number of rotations of the screw, etc. Give it.

When the reaction temperature in the contact zone is lower than the melting point of the supplied base resin, the base resin is not sufficiently melted in the contact zone. Insufficient kneading with the resin causes the coating film inside the resin to be exposed on the surface where the processing liquid or the processing liquid vapor intervenes, or the processing liquid or the processing liquid vapor penetrates into the resin and coats the inside of the resin. The chance of contact with the film decreases, and the decomposition reaction rate of the coating film decreases, which is not preferable. Further, when the reaction temperature in the contact zone exceeds the thermal degradation temperature of the supplied base resin, the resin with a coating film is locally heated to a temperature equal to or higher than the thermal degradation temperature of the base resin, and Is deteriorated, and the resulting resin cannot be used as a recycled material.

On the other hand, in the present invention, as described above, the reaction pressure in the contact zone is set so as to create a gas-liquid coexistence state of the treatment liquid vapor / treatment liquid-molten resin system in the contact zone. It is desirable that the vapor pressure of the processing liquid corresponds to the reaction temperature selected under the conditions of the above conditions. However, as long as the gas-liquid coexistence state of the processing liquid vapor / processing liquid-molten resin system is maintained in the contact zone, A third component (for example, an inert gas such as a nitrogen gas, a helium gas, an argon gas, or the like) may be injected into the contact zone. However,
If the treatment pressure is lower than the vapor pressure of the treatment liquid corresponding to the set reaction temperature, the decomposition reaction rate of the coating film becomes slow, so that the coating film is reduced to a desired degree for recycling the resin containing the coating film. It is not preferable because it cannot be miniaturized. Further, when the reaction pressure in the contact zone is higher than the vapor pressure of the processing liquid corresponding to the set reaction temperature, the high-temperature / high-pressure processing liquid and / or the Pressure region, that is, a portion upstream of the high-pressure processing liquid and / or a high-temperature / high-pressure processing liquid vapor inlet for appropriately forming a void based on a gas-liquid coexistence state, and Insufficient sealing with the molten resin at the point between the discharge hole of the processing liquid vapor and the exhaust port, and therefore, the contact between the resin containing the coating film and the hot processing liquid or the processing liquid vapor is efficiently performed. It is not preferable because the reaction is not performed and the decomposition reaction rate of the coating film decreases.

Therefore, the method of the present invention is characterized in that a pressure adjusting mechanism is provided in the contact zone. The pressure adjusting mechanism makes the high-temperature and high-pressure processing liquid formed in the contact zone and / or the vapor pressure holding region by the vapor thereof coexist, and maintains the vapor pressure of the processing liquid. Maintain a temperature corresponding to the vapor pressure of the processing liquid, thereby increasing the temperature and temperature in the contact zone.
It is an object of the present invention to maintain a high pressure state under constant conditions (temperature and pressure) suitable for a decomposition reaction of a coating film. Therefore,
The pressure adjusting mechanism is not particularly limited as long as the above-described object can be achieved, but the cylinder (the high-pressure cylinder) located upstream of the devolatilization zone and near the end of the contact zone is not particularly limited. A discharge hole for processing liquid vapor at an intermediate portion between the inlet of the processing liquid and / or the high-temperature and high-pressure processing liquid vapor and the exhaust port, a pipe connected thereto, and a pressure control provided in the pipe. It is preferable to be constituted with a valve.

By providing the pressure adjusting mechanism, excess processing liquid and its vapor present in the extruder are discharged out of the extruder system through a pipe through a discharge hole of the processing liquid vapor. The processing liquid and / or its vapor will be supplied into the extruder. And
Until the excess processing liquid or its vapor passes through the pressure regulating valve, a part or all of the processing liquid or the vapor is kept in a hot liquid state, and in the contact zone which is a component soluble in the hot liquid. The decomposition product is discharged out of the extruder system together with the hot liquid,
This leads to the process liquid recovery step described below, which is another feature of the method of the present invention. As a result, impurities in the recycled resin are reduced, and recombination of the decomposed coating film components can be reduced.

The longer the residence time of the resin containing the coating film in the contact zone, ie, the longer the decomposition reaction time of the coating film, the more the decomposition and miniaturization of the coating film. Therefore, the pressure and temperature of the resin containing the coating film in the contact zone, the supply amount of high-temperature and high-pressure processing liquid and / or its vapor, the cylinder diameter of the extruder, the screw configuration, the screw length, the screw rotation speed, etc. Further, in some cases, the reaction time is proportional to the throughput of the resin containing the coating film as long as the extruder is operated while operating parameters such as the supply amount of the coating film decomposition accelerator are kept constant. That is, as the amount of the resin containing the coating film is smaller, the decomposition reaction of the coating film progresses, and the fineness of the coating film is improved, but the effect is adverse in terms of the production efficiency of the recycled resin. The preferable range of the treatment amount of the resin containing the coating film in the method of the present invention is complicatedly affected by the various operating parameters described above, and cannot be unconditionally determined.
In an extruder with a cylinder diameter of 5 mmφ and L / D (ratio of screw length to cylinder diameter) = 60, 10 to 10
70 kg / H, especially 20 to 60 kg / H is desirable. When the cylinder diameter is other than 55 mmφ, the processing amount is preferably within the range limited by the following mathematical expression 1.

[0039]

(Equation 1)

In the method of the present invention, in order to efficiently contact the resin containing the coating film with the high-temperature and high-pressure treatment liquid and / or its vapor in the contact zone, as described above, It is necessary to create a gas-liquid coexistence state of the processing liquid vapor / processing liquid-molten resin system in the zone, and appropriately form a void portion that holds the high-temperature and high-pressure processing liquid and / or the vapor pressure of the vapor, Accordingly, the porosity in the contact zone, that is, the ratio of the void portion in the contact zone and the processing liquid supply rate, that is, the supply amount of the high-pressure processing liquid and / or the high-temperature high-pressure processing liquid vapor Need to be optimized. The appropriate supply amount of the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid vapor is:
55 mm depending on the type of the coating film and the base resin, the pressure and temperature of the resin including the coating film in the contact zone, the pressure and temperature of the supplied processing liquid and / or its vapor, etc.
In an extruder having a cylinder diameter of φ, 0.1 to 0.8 per kg / H of a resin with a coating to be treated (resin including a coating).
It is preferably kg / H. The supply amount of the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid vapor is 0.1 kg.
If the ratio is less than / H, the decomposition reaction rate of the coating film in the contact zone is undesirably low. Conversely, when the supply amount of the high-pressure processing liquid and / or the high-temperature / high-pressure processing liquid vapor is more than 0.8 kg / H, the processing liquid or the vapor thereof from the resin with a coating film in the devolatilization zone. Is insufficient, and as described above, the recycled resin discharged from the recycled resin discharge port (die) of the cylinder is in a fired state, which is not preferable because the strand may not be drawn. In the method of the present invention, as described above, the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid can be injected from the inlet of the high-temperature and high-pressure processing liquid vapor. In order to increase the contact efficiency between the resin containing the coating film and the high-temperature / high-pressure processing liquid and / or its vapor in the contact zone, a high-pressure processing liquid is injected from the injection port, and the processing is performed in the contact zone. It is preferable to create a vapor-liquid coexistence state of the processing liquid vapor / processing liquid-molten resin system in the contact zone by generating the liquid vapor.

In the present invention, a pipe is connected to the above-mentioned high-pressure processing liquid and / or a high-temperature and high-pressure processing liquid vapor inlet, and the high-pressure processing liquid such as a metering pump is connected to the upstream end of the pipe. And / or by providing a device for quantitatively supplying the high-temperature and high-pressure processing liquid vapor to feed the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid vapor into the contact zone at the above-described appropriate amount. You can.

Next, for example, when treating a resin containing a coating film that is difficult to hydrolyze or alcoholy such as a urethane paint, the resin with the coating film is treated with a high-temperature and high-pressure treating solution in the presence of the above-mentioned coating film decomposition accelerator. When it comes into contact with the vapor, the supply amount of the coating film decomposition accelerator is preferably about 0.01 to 10 g / H per 1 kg / H of the treated resin. When the supply amount of the coating film decomposition accelerator is less than the appropriate amount, the decomposition reaction of the coating film is insufficient, and when the amount is more than the appropriate amount, the coating film decomposition accelerator erodes the base resin, Any of these is undesirable, for example, a coating film decomposition accelerator mixed into the recycled resin adversely affects the physical properties of the recycled resin. As a method of adding the coating film decomposition accelerator, a method of adding to a crushed product of a resin containing a coating film and supplying it from a resin supply port with a coating film at an upstream end of a cylinder of the extruder, or a method of supplying the resin into the extruder from the injection port It is appropriate to use a method of dissolving in a processing liquid to be supplied and supplying the same.

The number of revolutions of the screw of the extruder depends on the amount of the resin coated with the coating film and the function of renewing the surface of the molten resin in the contact zone, ie, the decomposition reaction of the coating film contained in the molten resin in the contact zone. Affect. In the method of the present invention,
When using an extruder having a cylinder diameter of 55 mmφ, it is preferable to set the screw rotation speed to about 100 to 400 rpm. If the screw rotation speed is less than 100 rpm, kneading of the coating film and the base resin in the contact zone becomes insufficient, and the coating film inside the resin is exposed to the intervening surface of the processing liquid or the processing liquid vapor, or The chance that the processing liquid or the processing liquid vapor penetrates into the resin and comes into contact with the coating inside the resin is reduced, so that the so-called surface renewal function of the molten resin is reduced, and the decomposition reaction rate of the coating is reduced. It is not preferable. When the screw rotation speed is higher than 400 rpm, the output power of the molten resin by the rotation of the screw is increased, and the coating film is applied to the supply amount of the high-pressure processing liquid and / or the high-temperature and high-pressure processing liquid vapor in the contact zone. The amount of resin transported is increased, the residence time of the resin with the coating film in the contact zone is shortened, the filling area of the molten resin in the resin seal portion is shortened, and the sealing with the molten resin is weakened, so that the coating film is weakened. While the decomposition reaction rate of the base resin decreases, the temperature of the base resin increases, and the base resin deteriorates, which is not preferable. The control of the screw rotation speed can be performed by a known method, for example, a method using a variable speed motor as a driving device can be suitably adopted.

By the way, in the method of the present invention, in order to stabilize the quality of the regenerated material, the resin containing the coating film existing in the space defined by the cylinder and the screw in the cylinder is used. Temperature conditions need to be kept constant. In other words, a heating mechanism is necessary to raise the temperature at the start or to adjust the set temperature that differs depending on the type of the resin with a coating film to be treated, while a large frictional heat is generated due to the frictional force between the molten resin and the cylinder. In order to increase the temperature, a cooling mechanism is required. For the cylinder, temperature control such as heating and cooling is performed in several sections according to the length of the screw. It is necessary. Therefore, the extruder used in the present invention adopts a block system for the cylinder, and is provided with a heat transfer device for heating or cooling the cylinder from the outside around the cylinder in each block unit. desirable. As such a heat transfer device, a known device such as an electric heater wound around the cylinder or a jacket structure can be used, and for each block of the cylinder, a heating medium such as steam, or A cooling medium such as cooling water may be flowed through the heat transfer device.

As described above, the extruder used in the method of the present invention, particularly the twin-screw extruder of the mesh type co-rotating (or counter-rotating), which is preferably used, has a self-cleaning property. It is a machine with excellent temperature control, accurate temperature control, and excellent surface renewal function and devolatilization ability of molten resin. (1) Processing amount of resin with coating film, screw configuration, screw rotation speed (2) Since the screw is of the segment type and the cylinder is of the block type, it is possible to remove the molten resin depending on the purpose. Change of screw configuration such as adding or removing a volatilization zone,
It is easy to change the axial length of the kneading part. (3) By changing the set pressure of the installed pressure control valve, it is suitable for the decomposition reaction of the coating film according to the type of the resin with the coating film to be treated. It is also a flexible machine for the production process with considerable flexibility in processing conditions, such as being able to easily maintain conditions (pressure and temperature).

In the method of the present invention, when the required quality for the regenerated product is severe, an impact modifier, a compatibilizer, or the like is added during the kneading process in the extruder, or the regenerated pellets are added to the extruder again. An automatic backwash filter for removing large coating films continuously is installed at the resin outlet (die) of the extruder, supplying it to the resin supply port with coating film and passing it through the extruder. Of course, the quality of the recycled product can be made closer to that of a virgin material.

Therefore, the resin-coated resin treatment step of the present invention comprises:
This will be described in detail below with reference to the accompanying drawings. FIG.
FIG. 1 is a schematic flow chart showing one embodiment of a resin-coated resin treatment step in the method of the present invention. In FIG. 1, 1 is a tank, 2 is a metering pump, 3 is a pressure regulating valve, 4 is a twin screw extruder, 41 is a cylinder, 42 is a screw,
43 is a resin supply port with a coating film attached to the cylinder 41, 44 is a recycled resin discharge port attached to the cylinder 41, 45 is a high-pressure processing liquid (or processing liquid vapor) injection port attached to the cylinder 41, 46. Is a processing liquid vapor discharge hole attached to the cylinder 41, and 47 is a cylinder 41
The exhaust port attached to the, and 48 is a heat transfer device.

The cylinder 4 of the twin screw type extruder 4
A screw 42 is disposed in the screw 1, and the screw 42 is rotatably driven at one end by a driving device not shown in FIG. 1. A resin supply port 43 with a coating film is provided on the drive device side of the cylinder 41, and a recycled resin discharge port 44 is provided at the other end of the cylinder 41. When the resin is supplied, the resin is carried to the recycled resin discharge port 44 side with the rotation of the screw. Cylinder 41
Since the heat transfer device 48 is attached to the outer periphery of the cylinder 41 and the cylinder 41 is heated or cooled, the resin with the coating film advances in the space 420 formed by the cylinder 41 and the screw 42 in the cylinder 41. Meanwhile, it is melted and maintained at an appropriate temperature.

The screw 42 is connected to the solid transport zone 42
1, a melting zone 422 and a melt transport zone 423. The melt transport zone 423 further includes a contact zone 424, a devolatilization zone 425, and a pressurization zone 4.
26, and at least a part of the contact zone 424 serves as a surface updating portion 427. FIG.
In the melting zone 422, the crushed product of the coated resin which is crushed to an appropriate particle size by a crushing device not shown and supplied to the coated resin supply port 43 is also shown in FIG. The mixture is heated and melted by a kneading element (kneading disk) that is not heated and plasticized, and is sent to the contact zone 424 which is the most upstream part of the melt transport zone 423.

At a position located near the upstream end of the contact zone 424 of the cylinder 41, a high-pressure processing liquid (or processing liquid vapor) inlet 45 is provided, which is connected to the tank 1 via the metering pump 2. They are connected by piping. An appropriate amount of treatment liquid enters the metering pump 2 from the tank 1 through the pipe,
The pressure is increased to a predetermined pressure by the metering pump 2, and is again supplied to a high-pressure processing liquid (or processing liquid vapor) inlet 45 through a pipe. And high-pressure processing liquid (or processing liquid vapor)
The treatment liquid fed from the inlet 45 to the contact zone 424 comes into contact with the molten resin containing the coating film also sent to the contact zone 424, and is heated by the high-temperature molten resin, and a part or the entire amount thereof is evaporated. As a result, vapor of the processing liquid is generated. At the same time, the hydrolysis or alcoholysis reaction of the coating film proceeds by this contact, and the coating film is reduced in molecular weight and refined to a desired level.

At a position near the end of the contact zone 424 of the cylinder 41, a processing liquid generated by evaporation of the processing liquid fed to the contact zone 424 from the high-pressure processing liquid (or processing liquid vapor) inlet 45 is provided. A processing liquid vapor discharge hole 46 for discharging vapor is provided, and a pressure adjusting valve 3 is provided in a pipe connected to the processing liquid vapor discharge hole 46. Further, in the space 420, from near the end of the melting zone 422, on the upstream side of the high-pressure processing liquid (or processing liquid vapor) inlet 45, and near the upstream end of the contact zone 424. The kneading element is located at a position from the position near the end of the contact zone 424 and near the upstream end of the devolatilization zone. (Not shown in FIG. 1), the contact zone 4
Filled areas (seal portions) 428 and 429 of the molten resin are formed so that high-temperature and high-pressure processing liquid based on the processing liquid fed to 24 and / or its vapor can be sealed.

As a result, a vapor pressure holding region 430 is secured in the contact zone 424 based on the evaporation of the processing liquid fed into the contact zone 424 from the high-pressure processing liquid (or processing liquid vapor) inlet 45. For this purpose, the coating existing inside the resin is positively applied to the surface (the treatment liquid vapor layer and the resin layer) by the screw provided mainly in the contact zone 424 and serving mainly for kneading. Surface renewal portion 4 that allows the processing liquid or the processing liquid vapor to actively penetrate into the molten resin and increase the chance of contact with the coating film existing inside the resin while exposing the processing liquid or the processing liquid vapor to the molten resin.
27 are expressed.

By securing the vapor pressure holding region 430 in the contact zone 424, the pressure regulating valve 3 is set to a pressure corresponding to the saturated vapor pressure of the processing liquid at a temperature suitable for the decomposition reaction of the coating film. For example, the vapor pressure holding region 430 is maintained in a saturated vapor state, the temperature is also maintained at a temperature corresponding to the saturated vapor pressure, and the high temperature / high pressure state of the contact zone 424 is a constant optimum for the decomposition reaction of the coating film. Temperature and pressure conditions.

As described above, the molten resin containing the coating film refined to a desired level is supplied to the next devolatilization zone 425.
Transported to An exhaust port 47 is attached to the cylinder 41 located in the devolatilization zone 425.
7 is further connected to a vacuum device not shown in FIG. 1 through a pipe connected thereto. Devolatilization zone 4
The molten resin sent to 25 contains a processing liquid vapor and / or a processing liquid that causes foaming at the time of discharge from a regenerated resin discharge port 44 described later. The molten resin expands, and volatile components such as processing liquid components contained therein are discharged from the exhaust port 47 to the vacuum device side.

The molten resin devolatilized in the devolatilization zone 425 is sent to a pressure rising zone 426, which is the final stage of the screw configuration of the twin screw type extruder 4. A recycle resin discharge port 44 is attached to the cylinder 41 located at the end of the pressure rising zone 426, and a die nozzle portion (not shown in FIG. 1) is provided at the recycle resin discharge port 44. Have been. The molten resin delivered to the pressurizing zone 426 is compressed under pressure, and can only pass through the nozzle holes (also not shown in FIG. 1) of the die nozzle portion, overcoming the resistance of the die nozzle portion. A sufficient pressure is applied, the resin is extruded from the nozzle hole, and discharged from the recycled resin discharge port 44 in the form of a strand.

The coating film that has passed through the contact zone 424 and has been refined to a desired level is driven by the rotation of the screw 42 to devolatilize the zone 425 and pressurize the zone 42.
While advancing 6, it is kneaded and contained in the molten resin. As a result, the regenerated resin in which the coating film refined to a level usable as a regenerated material is uniformly and finely dispersed in the base resin is discharged in a strand form from the regenerated resin discharge port 44.

The recycled resin discharged in the form of a strand from the recycled resin discharge port 44 is cooled and solidified in a water-cooled water tank (not shown in FIG. 1), and is also shown in FIG. The pellet is cut by a pelletizer that is not used.

Next, the processing liquid collecting step which is another characteristic of the method of the present invention will be described in detail with reference to the drawings. The outline of the treatment liquid collecting step in the method of the present invention is as shown in FIG. The substance to be treated in this step is an exhaust gas discharged to the outside of the extruder system through a pressure regulating valve constituting a pressure regulating mechanism of the extruder in the resin-coated resin treating step. The exhaust gas mainly contains decomposition products of the coating film and vapor of the processing liquid based on contact between the resin with the coating film and the processing liquid and / or the vapor thereof in the contact zone of the extruder. Decomposition products of the coating film include low-boiling compounds such as formaldehyde, n-butyl alcohol and isobutyl alcohol, and high-boiling compounds such as 1.6-hexanediol, trimethylolpropane, melamine and isophthalic acid. ing. Also,
The temperature of the exhaust gas varies depending on the temperature of the resin with a coating film in the contact zone of the extruder, the amount of the treatment liquid and / or the vapor of the treatment liquid, the state of keeping the temperature of the extruder, and the like. Or higher than the boiling point of the resin and the temperature of the resin with a coating film, for example, when the treatment liquid is water, the temperature is as high as 100 to 250 ° C.

In the treatment liquid recovery step of the present invention, the above-mentioned high temperature exhaust gas is first introduced into the lower part of the first distillation column 21 through the pipe 211. The upper part of the first distillation column 21 is supplied with a purification treatment liquid through a pipe 223, and while being brought into countercurrent contact with the exhaust gas rising from the lower part in the first distillation column 21, the above-mentioned low boiling point The compound and the high-boiling compound are separated by distillation. In other words, the first
A part of the processing liquid containing the high-boiling compound extracted from the bottom of the distillation column 21 is circulated to the bottom of the first distillation column through a pipe 214 branched from a discharge pipe 213 of the first distillation column can liquid pump 26. However, the remaining part is maintained at the bottom of the first distillation column 21 so as to keep the liquid level constant.
While being controlled by the liquid level control valve 29 provided in the discharge pipe 213, the liquid is drawn out of the system by the first distillation tower can liquid pump 26 through the pipe 212 and the discharge pipe 213 of the first distillation tower can liquid pump 26. It is. The amount of the high-boiling-point compound-containing treatment liquid withdrawn out of the system depends on the exhaust gas treatment flow rate in the first distillation column 21 and the operating temperature and pressure conditions of the first distillation column 21 described later. It is preferably about 1 to 3% by weight of the total amount of exhaust gas introduced into one distillation column 21. Therefore, this high-boiling-point compound-containing treatment liquid has a considerably high BOD value or COD value. However, when the treatment flow rate of the exhaust gas in the first distillation column 21 is small, it can be directly discarded. . However, from the viewpoint of preventing pollution, it is preferable to perform pollution-free treatment by supplying the wastewater to a known suitable wastewater treatment facility such as an activated sludge treatment facility or a waste liquid combustion treatment facility, or by handing it over to a waste disposal company. On the other hand, an exhaust gas containing the low-boiling compound and the vapor of the processing liquid is discharged from the top of the first distillation column 21, and is introduced into a lower portion of the second distillation column 22 through a pipe 215.

The operating pressure in the first distillation column 21 is not particularly limited. Therefore, the first distillation column 21 can be operated under reduced pressure or under increased pressure. However, in the case of the reduced pressure operation, a decompression equipment such as a vacuum pump is required. Since the equipment cost is large, such as a demand for pressure resistance, the method of the present invention is preferably operated at a normal pressure of 0 to 0.2 kg / cm ² G. The operating temperature in the first distillation column 21 is, as described above, the amount of the exhaust gas introduced into the first distillation column 21 at the above-mentioned operating pressure, as described above.
It may be appropriately selected so that it can be separated into a treatment liquid containing a high-boiling compound of about% by weight and a remaining exhaust gas containing a vapor of the low-boiling compound and the treatment liquid. That is, the first
The operation temperature of the distillation column 21 should be selected in consideration of the treatment flow rate and composition of the exhaust gas, the operation pressure condition, and the like so that the above-described separation can be performed. When operating at a bottom temperature of 100 to 12
It is desirable that the temperature is 0 ° C and the tower top temperature is 100 to 105 ° C. When the operating temperature of the first distillation column 21 is out of this range,
This is not preferable because the above separation becomes insufficient.

Next, the second distillation column 22 is passed through a pipe 215.
The exhaust gas containing the low-boiling compound and the vapor of the processing liquid introduced into the lower part of the column is brought into countercurrent contact with the reflux liquid flowing down from the upper part while ascending in the second distillation column 22. As a result of this contact treatment, the vapor of the treatment liquid containing a low-boiling compound is distilled off from the top of the second distillation column 22.
The refrigerant is guided to the condenser 23 through 25 and is condensed by a refrigerant, for example, cooling water flowing through the pipes 231 and 232. The condensate, that is, the treatment liquid containing a low-boiling compound, is further led to the gas-liquid separator 24 through the pipe 226, where the non-condensable gas is separated.
7, a part thereof is returned to the upper part of the second distillation column 22 as a reflux liquid by the pump 28 through the pipe 228 and the pipe 229. Then, the remaining condensate, that is, the low-boiling-point compound-containing treatment liquid is drawn out of the system by the pump 28 through the pipes 227 and 228. Further, the above-mentioned non-condensable gas is also drawn out of the system through the pipe 241.

The amount of the low-boiling compound treatment liquid extracted to the outside of the system depends on the processing flow rate of the exhaust gas containing the low-boiling compound and the vapor of the processing liquid in the second distillation column 22, the second distillation column 2
Although it depends on the operating temperature and pressure conditions in 2,
0.5 to 5 of the total amount of exhaust gas introduced into the first distillation column 21
It is preferable that the amount is about weight%. Therefore, the low-boiling compound-containing treatment liquid contains the low-boiling compound at about 1 to 5% by weight and has a considerably high BOD value and COD value. Similarly to the above, when the treatment flow rate of the exhaust gas in the first distillation column 21 is small, it is also possible to perform the disposal treatment as it is. However, from the viewpoint of pollution prevention, it is preferable to perform pollution-free treatment by supplying the wastewater to known appropriate wastewater treatment equipment such as activated sludge treatment equipment and wastewater combustion treatment equipment, or by delivering it to a waste disposal company.

As described above, the vapor of the treatment liquid containing a low-boiling compound is distilled from the top of the second distillation column 22 in an amount of about 0.5 to 5% by weight of the total amount of the exhaust gas introduced into the first distillation column 21. By leaving the solution, the purified liquid is recovered from the bottom of the second distillation column 22. As described above, this purified treatment liquid has a low boiling point compound content of about 1 to 5% by weight because the treatment liquid containing a low boiling point compound distilled off from the top of the second distillation column 22 has a low boiling point. 100 to 30 boiling compounds
It contains about 0 ppm. The purification solution is
The liquid is withdrawn from the bottom of the second distillation column 22 and a part thereof is circulated to the bottom of the second distillation column 22 through the pipe 221, the discharge pipe 222 of the second distillation tower can liquid pump 27, and the pipe 224 as a bottom liquid. Further, another part of the purification treatment solution is the first solution.
As washing water of the exhaust gas introduced into the distillation column 21, it is supplied to the upper part of the first distillation column 21 through a pipe 223 branched from a discharge pipe 222 of the second distillation tower can liquid pump 27.
The supply of the washing water to the first distillation column 21 is preferably performed at a constant flow rate by the flow rate control valve 31 provided in the pipe 223. Note that the supply amount of the washing water is such that distillation separation of the exhaust gas containing the low-boiling compound and the vapor of the processing liquid in the first distillation column 21 and the high-boiling compound-containing processing liquid can be achieved. First distillation column 2
Exhaust gas treatment flow rate and exhaust gas composition in 1, first distillation column 2
In the method of the present invention, it should be determined in consideration of the operating temperature and pressure conditions of 1, etc., but the same amount as the high boiling compound-containing treatment liquid extracted from the bottom of the first distillation column 21 to the outside of the system. Therefore, it is preferably about 1 to 3% by weight of the total amount of exhaust gas introduced into the first distillation column 21. Then, the remaining part of the purified liquid is supplied to the liquid level control valve 3 provided in the discharge pipe 222 of the second distillation column can liquid pump 27 so as to keep the liquid level at the bottom of the second distillation column 22 constant.
While being controlled at 0, it is sent to the tank 1 (shown in FIG. 1) in the resin treatment step with the coating film by the second distillation tower can liquid pump 27 through the pipe 221 and the discharge pipe 222 of the second distillation tower can liquid pump 27. It is circulated and reused as a decomposition solution for the resin with a coating film.

The operating conditions of the second distillation column 22 are such that the separation of the low-boiling-point compound-containing treatment solution and the purification treatment solution in the second distillation column 22 can be achieved as in the case of the first distillation column 21. It suffices if there is, and it may be selected appropriately. In the process of the present invention, it is preferable to operate at a normal pressure of 0 to 0.2 kg / cm ² G, at a temperature of 100 to 105 ° C. at the bottom and 90 to 100 ° C. at the top. If the pressure or the temperature is higher than the above range, a large amount of heat must be added to achieve the desired separation between the low-boiling-point compound-containing treatment liquid and the purification treatment liquid, which is not preferable because the operation cost increases. . If the pressure is lower or lower than the above range, as described above, a decompression facility such as a vacuum pump is required, or formaldehyde, one of the low boiling compounds, is not sufficiently dissolved in the processing liquid in the condenser 23. And is discharged from the gas-liquid separator 24 together with the non-condensable gas to the outside of the system, which may cause a pollution problem or is not preferable.

In the method of the present invention, the distillation column used for the first distillation column 21 and the second distillation column 22 is usually a column tower such as a bubble bell tower, a perforated plate tower or a packed tower. May be used as a distillation column, and a larger hold-up is preferred, but it is not necessary to have a specially designed structure. For example, when using a packed tower, porcelain, metal or resin Raschig rings,
Any known filler such as a lessing ring, a pole ring, a Berl saddle, an interlock saddle, or the like may be used as long as it is regularly or irregularly filled. The number of stages and the length of the packed bed of these distillation columns are determined by the flow rate and composition of the exhaust gas and the processing solution introduced into these distillation columns, the flow rate and composition of steam and / or gas distilled out from the top of the tower, and the length of the bottom. The flow rate and composition of the processing liquid to be withdrawn, the operating temperature and pressure conditions of the distillation column, etc., and when using a packed column,
Further, it may be appropriately determined in consideration of the type of the filler and the characteristics thereof. In the method of the present invention, the first distillation column 21 and the second distillation column 22 are preferably of the same type, and are particularly preferably packed columns.

In the treatment liquid recovery step in the method of the present invention, as described above, the exhaust gas introduced into the first distillation column 21 is at a temperature between the boiling point of the treatment liquid and the resin temperature with the coating film, for example, the treatment liquid is water. In such a case, the temperature is as high as 100 to 250 ° C., and therefore, during the steady operation, the distillation separation of the exhaust gas containing the low-boiling compound and the vapor of the processing liquid in the first distillation column 21 and the processing liquid containing the high-boiling compound is performed. And the second distillation column 2
The method is characterized in that an external heat source is not required for the distillation separation of the low-boiling-point compound-containing treatment liquid vapor and the purification treatment liquid in 2 above. However, in the method of the present invention, a reboiler 25 is provided in the pipe 224, which is the bottom liquid circulation line of the second distillation column 22, in order to ensure the quality of the purified processing liquid at the startup of the processing liquid recovery step. Is preferred. Then, at the start-up of the processing liquid recovery step, fresh processing liquid is applied to the bottom of the second distillation column 22,
Pipe 221, discharge pipe 22 of second distillation column can liquid pump 27
2, circulated to the bottom of the second distillation column 22 by the second distillation column can liquid pump 27 through the reboiler 25 and the pipe 224, and in the reboiler 25, the pipe 251
Preferably, the circulating liquid is heated by a heat medium flowing through the pipe 252, for example, steam.

In the method of the present invention, as described above, the coating film decomposition product and the treatment liquid are distilled from the exhaust gas containing the low boiling point compound or the high boiling point compound of the coating film decomposition product and the vapor of the treatment liquid. For separation, two distillation columns, a first distillation column 21 and a second distillation column 22, are used. However, these distillation columns are stacked in two stages to form one distillation column. It is also possible to extract a high-boiling-point compound-containing treatment liquid, distill a low-boiling-point compound-containing treatment liquid from the top of the column, and collect a purified treatment liquid by side-cutting from the middle stage of the column. Further, a bottom liquid extraction pipe 212 from the bottom of the first distillation column 21 and a bottom liquid extraction pipe 2 from the bottom of the second distillation tower 22
21 and a condensate drain pipe 227 from the gas-liquid separator 24
And the like, and by keeping the bottom liquid level of the first distillation column 21 and the second distillation column 22 and the liquid level of the gas-liquid separator 24 constant, the first distillation column can liquid pump 26,
Second distillation column can liquid pump 27, pump 28, liquid level control valve 2
9 and the liquid level control valve 30 can also be omitted.

As described above, from the exhaust gas containing the decomposition product of the coating film composed of the low-boiling compound and the high-boiling compound and the vapor of the processing liquid, which is discharged out of the extruder system through the pressure control valve of the extruder. The low-boiling compounds and high-boiling compounds are separated by distillation to collect the processing liquid, which is recycled and reused as a processing liquid for decomposing the coating film in the resin with a coating, while the low-boiling compounds generated when the processing liquid is recovered By performing the pollution-free treatment of the treatment solution containing the high-boiling compound or the treatment solution containing the high-boiling compound, an economical method for continuously regenerating a resin with a coating film, which is free of pollution and which is an object of the present invention, is achieved.

[0069]

EXAMPLES Next, the method of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the method of the present invention is not limited thereto.

In the following Examples and Comparative Examples, when a material containing no coating film (crushed bumper molded product before coating) was used as a raw material in the resin treatment step with a coating film (Comparative Example 1).
The measurement results of the surface smoothness and mechanical properties of the pellets obtained in Examples and Comparative Examples (excluding Comparative Example 1) were obtained by using the measurement results of the surface smoothness and mechanical properties of the pellets obtained as blanks as described above. Expressed as relative to blank. That is, the measurement results of each of the examples and the comparative examples when the blank value is regarded as good are compared with the blank value, and the results are evaluated as “good / somewhat bad / bad”.
It was evaluated on a scale. The mechanical properties include tensile yield strength, tensile break elongation, flexural strength, flexural modulus,
Table 1 shows Izod impact strength (-30 ° C) and embrittlement temperature.
The measurement was carried out by the test method shown in FIG.

Example 1 (Treatment of Resin with Coating Film) A cylinder having a cylinder configuration and a screw configuration shown in FIG.
φ, the distance between the shafts is 46.0 mm, and the screw length is 44D using a co-rotating twin screw type extruder 4 having a length of 44D,
Raw material (crushed propylene bumper waste including ethylene-propylene rubber, alkyd-melamine coating, average particle size 8 m)
m) was supplied at a rate of 25 kg / H. Then, from the high-pressure processing liquid (or processing liquid vapor) inlet 45 via the tank 1 and the metering pump 2, water containing purified processing water obtained by collecting the following processing liquid is 8.4 kg / H. And set the cylinder set temperature to cylinder 41.
220 ° C. in each of the melting zone 422, the contact zone 424, the devolatilization zone 425, and the pressure rising zone 426
At the same time, the pressure control valve 3 was adjusted to maintain the internal gas phase pressure at 10 to 12 kg / cm ² G. Screw 4
When the extruder 4 was operated with the number of rotations of 2 at 300 rpm, the average residence time of the raw material in the cylinder 41 was about 2
It was 20 seconds, and a strand was obtained from the nozzle portion of the recycled resin discharge port 44 at the tip. This strand was cooled in a water-cooled water bath, and the pellet obtained by cutting with a pelletizer was dried, and the surface smoothness and mechanical properties were measured. Evaluation of the measurement results showed that both the surface smoothness and the mechanical properties were good. The measurement results of the mechanical properties were as shown in Table 1.

(Recovery of treatment liquid) During the operation of the extruder 4,
8.4k of exhaust gas from the extruder 4 through the pressure control valve 3
It was evacuated at a rate of g / H. The condensed water obtained by condensing this exhaust gas contained 1200 ppm of formaldehyde, 550 ppm of other low-boiling compounds, and 2000 ppm of high-boiling compounds, and had a BOD value of 2680 ppm and a COD value of 1040 ppm.
Therefore, the above-described exhaust gas treatment was performed using a treatment liquid recovery facility generally configured as shown in FIG. At this time, as both the first distillation column 21 and the second distillation column 22, a packed column having a diameter of 80 mmφ and a height of 3 m was used, and a 5/8 ″ SUS304 pole ring of 2 m was used as a packed material. First, water was poured into the bottom of the first distillation column 21, and the water was passed through the pipe 212, the discharge pipe 213 and the pipe 214 of the first distillation tower can liquid pump 26, and the water was supplied by the first distillation tower can liquid pump 26. Then, water was poured into the bottom of the second distillation column 22, and the pipe 221 and the discharge pipe 22 of the second distillation column can liquid pump 27 were discharged.
2. Water is circulated through the reboiler 25 and the pipe 224 by the second distillation column can liquid pump 27,
Steam was flowed to the heating side of the reboiler 25 through the pipes 251 and 252 to heat and boil water, and steam was distilled from the top of the second distillation column 22 through the pipe 225. In this state, as the washing water, 200 ml / H of water is allowed to flow from the upper part of the first distillation column 21 through the discharge pipe 222 and the pipe 223 of the second distillation tower can liquid pump 27, and the above-mentioned water is passed through the pipe 211. Was introduced into the lower part of the first distillation column.

After reaching the steady state, the conditions around the first distillation column 21 and the second distillation column 22 were as follows. That is, the exhaust gas at a temperature of 150 ° C. is introduced from the lower part of the first distillation column 21 at a rate of about 8400 ml / H (about 8.4 kg / H), while the washing water is supplied from the upper part of the first distillation column 21. The mixture was allowed to flow down at a rate of about 200 ml / H (about 0.2 kg / H), and the exhaust gas and the washing water were brought into countercurrent contact at a tower top temperature of 100 ° C and a tower bottom temperature of 105 ° C. From the bottom of the column, high-boiling compound-containing wastewater containing 7.7% by weight of high-boiling compounds was controlled at about 200 ml / H (about 0. 2kg /
H) through the pipe 212 and the discharge pipe 213 of the first distillation column can liquid pump 26 at the rate of H).
6 and extracted into a drum. This high-boiling compound containing wastewater has a BOD value of 37520 ppm and 1456
It had a COD value of 0 ppm, and was handed over to a waste disposal company together with a low-boiling-point compound-containing wastewater described below for treatment. On the other hand, an exhaust gas containing a low-boiling compound was passed through the pipe 215 from the top of the column to about 8400 ml / H
(About 8.4 kg / H) and was introduced into the lower part of the second distillation column 22. Second distillation column 22
Means a top temperature of 98 ° C., a bottom temperature of 101 ° C. and a reflux ratio of 1
And distills it from the top of the tower as steam.
It is led to a condenser 23 through 25, where it is condensed,
Pipe 226, gas-liquid separator 24, pipe 227, pump 28
And the amount of low-boiling compound-containing wastewater withdrawn through the pipe 228 is about 400 ml / H (about 0.4 kg
/ H). This low-boiling compound-containing wastewater contains 3.28% by weight of low-boiling compounds (formaldehyde: 2.25%).
%, Other low-boiling compounds: 1.03% by weight), and a BOD value of 37520 ppm and 14560 p.
It had a COD value of pm and was collected in drums before being handed over to a waste disposal company for treatment, as described above. Then, from the bottom of the column, while controlling the liquid level control valve 30 so that the liquid level can be kept constant, the purified treated water whose low boiling point compound content has been reduced to 200 ppm,
At a rate of about 7800 ml / H (about 7.8 kg / H), the discharge pipe 2 of the pipe 221 and the second distillation tower can liquid pump 27 is used.
The liquid was withdrawn by the second distillation column can liquid pump 27 through 22 and fed to the tank 1 (shown in FIG. 1) for circulating and reuse as the water for treating the coated resin.
As described above, a part of the purified water is used as the washing water, and about 200 ml / H (about 0.
2 kg / H)
Discharge pipe 222 and pipe 22 of distillation column can liquid pump 27
3 to the upper part of the first distillation column 21.

Example 2 In a tank 1, a 0.1% by weight aqueous solution of sodium hydroxide was prepared using purified treated water obtained by collecting a treatment solution, pure water, and commercially available sodium hydroxide (first-class reagent). And the above-mentioned 0.1% by weight of sodium hydroxide was changed to 8.4 kg / H of water containing purified treated water obtained by collecting the treated liquid from the high-pressure treated liquid (or treated liquid vapor) inlet 45. The aqueous solution was supplied at a rate of 8.4 kg / H.
pm) except that a dry pellet was produced in the same manner as in Example 1 and the surface smoothness and mechanical properties were measured.
Exhaust gas discharged through the pressure control valve 3 of the extruder 4 is treated, purified purified water is recovered, and alkyd in the raw material is recovered.
It was circulated and used as decomposed water for the melamine coating. The evaluation of the measurement results of the surface smoothness and mechanical properties of the dried pellets was both good. The measurement results of the mechanical properties are as shown in Table 1. In particular, the tensile elongation at break was measured in the purified treated water obtained by collecting the treated liquid from the high-pressure treated liquid (or treated liquid vapor) inlet 45. Was significantly superior to the case of supplying only water containing (Example 1). The amounts and qualities of the high-boiling compound-containing wastewater and low-boiling compound-containing wastewater obtained during the recovery of the treatment liquid, and the amount and quality of the purified treated water were the same as those in Example 1, and the wastewater was In the same manner as in Example 1, the waste was treated by a waste disposal company.

Comparative Examples 1 and 2 In Comparative Example 1, as a blank test, a crushed product of polypropylene bumper waste containing ethylene-propylene rubber as a raw material in Example 1 (with an alkyd-melamine coating film, average particle size of 8 mm) To a material containing no coating film (crushed bumper molded product before painting, average particle size 8 m)
m) and that the exhaust gas discharged through the pressure regulating valve 3 of the extruder 4 was not processed. In Comparative Example 2, a high-pressure processing liquid (or processing liquid vapor) inlet was used. Dry pellets were obtained in the same manner as in Example 1 except that neither the processing liquid nor the processing liquid vapor was supplied from Step 45, and the processing of exhaust from the pressure control valve 3 of the extruder 4 was not performed. Was manufactured, and the surface smoothness and mechanical properties were measured. Table 1 shows the measurement results of the mechanical properties, and Table 2 shows the evaluation of the measurement results of the surface smoothness and the mechanical properties.

[0076]

[Table 1]

[0077]

[Table 2]

Comparative Example 3 Dried pellets were produced in the same manner as in Example 1 except that the co-rotating twin-screw extruder 4 shown in FIG. 1 was opened to the atmosphere without installing the pressure regulating valve 3. .
It was difficult to maintain the resin temperature and the internal gas pressure in the extruder 4 at constant conditions, and the stable continuous operation of the extruder 4 was not possible. In addition, the amount of exhaust gas exhausted from the pressure control valve 3 of the extruder 4 was not constant, so that the exhaust gas treatment equipment could not be operated stably. The mechanical properties of the obtained dried pellets vary considerably, and the evaluation of the measurement results of the surface smoothness and the mechanical properties and the measurement results of the embrittlement temperature among the mechanical properties are shown as average values. As shown in FIG.

[0079]

[Table 3]

【The invention's effect】

As described above in detail, in the method for regenerating a resin with a coating film of the present invention, the molten resin with a coating film and a high-temperature resin are mixed in an extruder equipped with a pressure adjusting mechanism, particularly a twin-screw extruder.・ High pressure treatment liquid or treatment liquid vapor is brought into contact under a certain temperature and pressure condition, and the coating film is extruded from an extruder by decomposing and refining and uniformly and finely dispersing the resin in a resin. Based on reduction of production efficiency of regenerated material by batch processing in regenerating method of resin with coated film by hydrolyzing or alcoholicizing the coating film in an autoclave and making it finer, and based on static hydrolysis (or alcoholysis) of the coating film It is caused by the insufficiency of the ability of the coating film to finely disperse the resin in the resin and the instability of the operation in the regeneration method of the resin with the coating film by hydrolysis of the coating film (or alcoholysis) in a conventionally known extruder. Recycled resin With the solution to problems such as variations in the physical properties, continuous processing conditions and processing steps simple way, and can be reproduced stably film-coated resin. When a bumper is manufactured using the reclaimed product thus obtained, the appearance (surface smoothness) and physical properties of the virgin material are not significantly reduced. On the other hand, the processing liquid is recovered from the coating film decomposition product discharged through the pressure adjusting mechanism of the extruder and the exhaust gas containing the vapor of the processing liquid, and is recycled and reused. Since the appropriate wastewater treatment is performed on the contained waste liquid, the resin with the coating film can be reclaimed economically and without causing any pollution problem.

[Brief description of the drawings]

FIG. 1 is a schematic flowchart showing a preferred embodiment of a method for continuously regenerating a resin with a coating film according to the present invention.

FIG. 2 is a schematic flow chart showing a preferred embodiment of recovery of a processing solution used for continuous regeneration of a resin with a coating film according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 2 Metering pump 3 Pressure control valve 4 Twin screw extruder 21 1st distillation tower 22 2nd distillation tower 23 Condenser 24 Gas-liquid separator 25 Reboiler 26 1st distillation tower can liquid pump 27 2nd distillation tower can Liquid pump 28 Pump 29, 30 Liquid level control valve 31 Flow rate control valve 41 Cylinder 42 Screw 43 Coating resin supply port 44 Regenerated resin discharge port 45 High-pressure processing liquid (or processing liquid vapor) inlet 46 Processing liquid vapor discharge hole 47 Exhaust port 48 Heat transfer device 211, 212 Pipe 213 Discharge pipe of first distillation tower can liquid pump 214, 215 Pipe 221 Pipe 222 Discharge pipe of second distillation tower can liquid pump 223 to 229 Pipe 231, 232 Pipe 241 Pipe 251 , 252 Piping 420 Space 421 Solid transport zone 422 Melting zone 423 Melt transport zone 42 4 contact zone 425 devolatilization zone 426 boosting zone 427 surface renewal section 428,429 full area of molten resin 430 vapor pressure holding area

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29B 17/00-17/02 C08J 11/00-11/28

Claims (2)

(57) [Claims] In an extruder, a molten resin with a coating is brought into contact with a high-temperature and high-pressure treatment liquid and / or a vapor thereof to finely disperse the coating in the molten resin. When regenerating the resin, (1) a pressure adjusting mechanism is provided in a contact zone between the resin with a coating film and the high-temperature and high-pressure processing liquid and / or its vapor, and the coating film is subjected to constant temperature and pressure conditions. And disperse finely in the molten resin,
(2) The exhaust gas containing the decomposition product of the coating film and the vapor of the treatment liquid, which is discharged to the outside of the extruder system through the pressure adjusting mechanism, is continuously introduced into the distillation column to decompose the coating film. (3) A method for continuously regenerating a resin with a coating film, wherein the product is separated from the processing liquid, and (3) the processing liquid is circulated and reused as a decomposition treatment liquid for the resin with a coating film. 2. An extruder comprising: (a) a resin supply port with a coating film (b) a solid transport zone (c) a melting zone (d) a melt transport zone (e) a recycled resin discharge port (die); And (d) providing at least one high-pressure processing liquid and / or its vapor inlet and at least one exhaust port (vent) at a location to be a (c) melting zone and / or (d) melt transport zone; An intermediate portion between the injection port and the exhaust port is provided with a pressure adjusting mechanism including an exhaust hole for the processing liquid vapor, a pipe connected thereto, and a pressure adjusting valve provided in the pipe, and It is injected into a location on the upstream side of the injection port of the cylinder (on the side of the resin supply port with a coating film) and a location between the discharge port of the processing liquid vapor and the exhaust port of the cylinder to maintain a high temperature and high pressure state. Processing solution Beauty / or to form a seal by the molten resin for encapsulating the vapor, also,
2. The method for continuously regenerating a resin with a coating film according to claim 1, wherein the twin-screw extruder is provided with a screw having a shape mainly performing kneading between the seal portions.