JPH07117052A - Method and device for continuously regenerating resin with coating film - Google Patents

Abstract

PURPOSE:To continuously and stably regenerate a resin with a coating film without deteriorating the physical properties of a matrix resin by a method wherein a melted resin with a coating film is brought into contact with a steam or the like in a contact zone for finely dispersing the coating film in the melted resin in an extruder, and a pressure regulating mechanism is provided in the contact zone. CONSTITUTION:Broken pieces of a resin with a coating film supplied to a supply port 43 of a twin-screw extruder 4 are plasticized. High-pressure water is supplied to an injection port 45 near an upstream end of a contact zone 424 through a quantitative pump 2. The water comes into contact with the melted resin to turn to a steam. The coating film is hydrolyzed and finely dispersed by the steam. A steam discharge hole 42 is provided near the terminal end of the contact zone 424 and connected to a compression regulating valve 3. As screws 42, screws forming sealing parts 428, 429 for high-temperature and-pressure steam in the contact zone 424 are used. In this manner, the zone is kept at constant temperature and pressure optimum for decomposing the coating film. After the resin is passed through the contact zone 424, the air is removed through an air discharge hole 47 of a deaerating zone 425, and the resin is extruded from a nozzle hole of a die through a pressure raising zone 426.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling a resin with a coating film and an apparatus therefor, and more specifically, it uses an extruder equipped with a pressure adjusting mechanism to coat a resin contained in a molten resin. By bringing the film into contact with high-temperature / high-pressure water or steam, more preferably high-temperature / high-pressure water or steam in the presence of a coating film decomposition accelerator to make the film fine and uniformly disperse it in the molten resin, The present invention relates to a method for continuously regenerating a resin with a coating film, which has less deterioration in physical properties than a resin (virgin material) and has high productivity, and an apparatus therefor.

According to the method of the present invention, a paint to be hydrolyzed, in particular, a waste material of an automobile bumper coated with an alkyd melamine (or acrylic melamine) resin can be supplied to a twin screw type extruder equipped with a pressure adjusting mechanism. What is crushed to various levels is supplied to the twin-screw type extruder, and is preferably contacted with high temperature / high pressure water or steam under constant temperature / pressure conditions in the presence of a coating film decomposition accelerator. By hydrolyzing the resin with a coating film, by refining the resin with a coating film to a level not harmful when reused and by uniformly dispersing it in the molten resin, that is, the hydrolysis of the coating film and the resin By carrying out uniform dispersion in the same time, it becomes possible to reuse as a material for bumpers, instrument panels, etc.

[0003]

[Prior art and its problems] Poor paint bumpers, scrap cars, and waste bumpers generated by repair and replacement at the manufacturing stage of automobiles are partially crushed and then recycled as pallet materials for forklifts. However, in recent years it has been mainly landfilled. However,
The development of recycling technology has become an issue due to landfill restrictions, etc., and one of the attempts is to study how to reuse the reclaimed material that is simply crushed, pelletized and molded from the painted bumper as a material 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 the physical properties as a foreign matter, especially the impact resistance (impact strength, embrittlement temperature). The impact resistance, which is a required performance of bumpers and instrument panels, deteriorates, and the appearance and quality of large bumps on the surface of the molded product adversely affect the appearance and quality of the bumpers and instrument panels. It was impossible to reuse it for quality reasons. Therefore, in order to recycle the painted waste bumper to the original bumper, instrument panel, etc., it was necessary to perform some treatment on the coating film, such as peeling of the coating film.

As a method of treating a coating film from a resin with a coating film,
The following mechanical peeling methods are generally known. Extrusion /
The screen mesh method is a method in which a thermoplastic base resin is heated and melted, and an insoluble / infusible coating film is filtered / removed by an extruder filter, but a coating film having a size smaller than the mesh remains. The removal rate of the coating film is low. The specific gravity difference separation method is a method of separating the coating film by utilizing the difference in specific gravity between the polypropylene as the bumper base material and the coating film, but since it is necessary to finely pulverize the bumper, an economical fine pulverization technology is required. Development is required. The shot blast method is a method in which high-pressure air is used to spray organic or inorganic powder such as a suitable thermosetting resin onto the bumper surface at high speed to mechanically remove the coating film, but the processing time is long and complicated. There are problems such as difficulty in peeling off the coating film on the curved surface. The water jet method uses high-pressure water instead of the powder in the shot blast method, but this method also has the same problem as the shot blast method. The vibration compression method is a peculiar method that uses a special device to compress and vibrate the crushed product of the painted bumper to separate the coating film.It has a small environmental load and the sand and gravel attached to the waste bumper However, in order to further improve the appearance of the recycled bumper, there was a problem that the amount of residual coating film was not yet satisfactory.

Known chemical stripping methods such as a solvent swelling method, an alkaline liquid boiling method, an acidic liquid boiling method, and an organic salt solvent treatment method are used to decompose or physically decompose a coating film by immersing it in an acid or alkali solvent. However, depending on the type of solvent, there is a problem in that the base resin swells or is eroded and the quality of the recycled material deteriorates. Further, in a solvent that does not damage the base resin, it takes a very long time for peeling, which causes a problem in productivity. Furthermore, there is a problem that the waste liquid treatment requires a considerable amount of cost such as a neutralization step, and there is a concern that the organic solvent used for the treatment may affect the environment.

As another method, WO93-1232 discloses a hydrolysis and regeneration method of a resin with a coating film. That is, in this method, after crushing and washing the coated polypropylene bumper, it is heated at 110 to 240 ° C. in an autoclave.
At a temperature of 1.5 to 35 kg / cm ² G and water, alcohol or a mixture of both or steam thereof, in the presence or absence of a catalyst such as an acid or an alkali. Hydrolysis and / or alcoholysis are performed for 240 minutes, and then centrifugally dehydrated products are melt-kneaded and pelletized by a twin-screw extruder to obtain a recycled bumper material.

The disadvantage of this method is that (1) below 150 ° C., the hydrolysis and / or alcoholysis of the coating takes time because of hydrolysis and / or alcoholysis of the coating in an autoclave. On the contrary, when the temperature is higher than 160 ° C., the polypropylene of the base resin melts and adheres to form a block, which makes the centrifugal dehydration treatment of the next step difficult and the operating temperature is 150 to 160.
Limited to a narrow range of ℃, (2) batch processing,
It takes time to raise and pressurize and is inefficient. Therefore, the production efficiency of the recycled material is low, (3) the hydrolysis and / or alcoholysis of the coating film is static, and the action of shearing force is small, so there is no mechanical crushing of the coating film.

Further, a method for regenerating a resin with a coating film by bringing the resin with a coating film into contact with water and / or steam in an extruder to hydrolyze the components of the coating film is described in the above WO93-1232.
However, it is difficult to maintain a constant temperature / pressure condition when the coating film is contacted with water and / or steam in the extruder, as disclosed in JP-A-5-228936 and JP-A-5-228936. There are problems such as variations in the physical properties of the recycled resin that is used, and the inability to perform stable continuous recycling.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to continuously and stably regenerate a resin with a coating film in which the treatment conditions and the treatment steps are simple, and the physical properties of the original base resin are small. A method and apparatus therefor.

[0011]

Means for Solving the Problems The inventors of the present invention continuously and continuously contact a molten resin with a coating film with water or steam at high temperature and high pressure in an extruder, and
As a result of diligent studies to develop a stable regeneration method, as an apparatus at that time, an extruder with a device such as a cylinder heating device, a screw configuration, and an injection / exhaust system, particularly a twin-screw type extruder is used. The inventors have found that this is possible by using them, and have reached the present invention.

That is, the method and apparatus of the present invention are (1) a resin supply port with a coating film (2) a solid transport zone (3) a melting zone (4) a melt transport zone (5) a recycled resin discharge port (die) And at least one high-pressure water or steam inlet and at least one exhaust port (vent) at the location of the (3) melt zone and / or (4) melt transport zone of the cylinder, and both ports A pressure adjusting mechanism is provided in the middle of the position of the cylinder, and the pressure adjusting mechanism mounting port of the cylinder and the exhaust port are located upstream of the injection port of the cylinder (resin supply port with coating film). A seal part made of molten resin for enclosing water or steam that has been injected into a high-temperature / high-pressure state is formed at a point, and a gap between the seal parts has a shape mainly for kneading. Extruder having a structure as provided Liu, particularly using a two-screw extruder, in the extruder,
This can be achieved by bringing the coating film contained in the molten resin into contact with water or steam at high temperature and high pressure to make it fine, and uniformly dispersing the coating film in the molten resin.

The method and apparatus of the present invention will be described in detail below. In the method of the present invention, the coating film is decomposed / deteriorated by contact with high-temperature / high-pressure water or water vapor, and at the same time mechanically pulverized to lower the molecular weight and decompose into fine particles, which are dispersed in the base resin. To do. Therefore, the coating film component of the resin with a coating film used in the present invention is not particularly limited as long as it can be subdivided by contact with high-temperature / high-pressure water or water vapor to decompose or deteriorate. However, hydrolyzable alkyd-melamine resin coating film, acrylic-melamine resin coating film and the like are preferable.

However, in the method of the present invention, when the resin with a coating film is brought into contact with water or steam at high temperature and high pressure, a coating film decomposition accelerator can be appropriately brought into contact with the coating film. Therefore, as the coating film component of the coating resin used in the present invention, the hydrolyzable alkyd-
In addition to melamine resin coatings and acrylic-melamine resin coatings, heat-curable urethane-based coatings composed of polyisocyanate resin and polyol resin that are not easily hydrolyzed by contact with high-temperature / high-pressure water or steam That is, it also includes a one-pack type urethane paint and a two-pack type urethane paint.

Examples of the above-mentioned film decomposition accelerator include acids such as hydrochloric acid, phosphoric acid, acetic acid and oxalic acid, and alkali metals and alkaline earth metals such as sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide. Preferable examples include alkalis such as hydroxides, sodium salts such as sodium phosphate, sodium hydrogen phosphate and sodium acetate, and salts such as 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 components with hot water or steam.

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 contact condition of the coating film with high temperature / high pressure water or steam. , For example, polypropylene, elastomer modified polypropylene, polyolefin such as polyethylene, polyphenylene oxide, modified polyphenylene oxide (including styrene modified polyphenylene ether)
Polyphenylene oxide resin, ABS resin, A, etc.
S resin, polyamide resin, polyester resin, polycarbonate resin, polyacetal resin and the like are preferable. Among these, polyolefins, which are the mainstream of automobile bumper materials, particularly resins mainly composed of polypropylene can be preferably cited.

In the method of the present invention, the temperature at which the resin with a coating film is brought into contact with hot water or steam in the extruder is selected depending on the type of the base resin and the coating film used. Usually, it may be higher than the melting point of the base resin and lower than the heat deterioration temperature, and within this range, it may be maintained at a constant temperature suitable for hydrolysis of the coating film or decomposition by the coating film decomposition accelerator. However, as long as the temperature of the base resin does not deteriorate, it is preferable that the temperature is as high as possible because decomposition and miniaturization of the coating film can be efficiently performed. The pressure at this time may be a pressure that can create a gas-liquid coexisting state in the contact zone between the resin with a coating film in the extruder and hot water or steam. Therefore, the temperature and pressure of high-temperature / high-pressure water or water vapor in the extruder used in the method of the present invention depend on the hydrolysis of the coating film or the coating film decomposition accelerator depending on the type of the coating resin used. The optimum conditions for the decomposition should be selected, and the conditions cannot be unconditionally limited, but in the polypropylene bumper material coated with the alkyd-melamine resin, 160 to 250 ° C., 8 to 50 kg / cm ²
G is suitable, 180 to 235 ° C., 10 to 30 kg /
cm ² G is more preferable.

By the way, according to the method of the present invention, a crushed product of a resin with a coating film is melted and then contacted with high temperature / high pressure water or steam to decompose / fine the coating film, and the finely divided coating film. And a molten resin are kneaded, the coating film is uniformly dispersed in the molten resin, and is characterized by using an extruder having a function of being discharged to the outside of the system, as such an extruder, Twin screw type extruder (Mating type /
Non-meshing type, same direction rotating type / different direction rotating type), special single-screw extruder, multi-screw extruder, twin-screw reactor, etc. are suitable. Among these, a twin-screw extruder of a twin-screw meshing type and rotating in the same direction (or different directions) is particularly preferable.

The twin-screw type extruder which is particularly preferably used in the method of the present invention is, as described above, provided with a coated resin supply port at one end and a recycled resin discharge port, that is, a die at the other end. A cylinder provided, a biaxial screw that is rotationally driven and meshes with each other, and a heat transfer device that heats or cools the cylinder from the outside are provided around the outer periphery of the cylinder.

The screw structure in the cylinder is composed of a solid transport zone, a melting zone (plasticizing zone) and a melt transport zone. The melt transport zone further comprises a coating resin and a high temperature / high temperature. It is preferably composed of a contact zone with high-pressure water (or steam), a devolatilization zone, and a pressurization zone. The resin with a coating is a space portion composed of the cylinder and the screw in the cylinder, and is driven by the rotation of the screw in the order of a solid transport zone, a melting zone, a contact zone, a devolatilization zone and a pressurizing zone. I will move,
In particular, the screw length should be as long as possible in order to prolong the residence time of the resin containing the coating film in the contact zone. Usually, a length of 20 to 60 times the cylinder diameter is preferable. The length of the biaxial reactor is preferably 5 to 20 times the cylinder diameter.

Each of the zones constituting the screw in the method of the present invention has the following functions. The solid transport zone is a propulsive force generated by a biaxial screw that meshes with each other the crushed products of the coated resin such as waste paint bumper supplied from the coated resin supply port provided at the upstream end of the cylinder by rotational driving. Is transferred to the next melting zone, namely the plasticizing zone. The coated resin supplied to the solid transport zone can be supplied from the coated resin supply port provided at the upstream end of the cylinder, and can be supplied to high temperature / high pressure water (or steam) on the downstream side. In order to efficiently decompose and miniaturize the coating film in the contact zone, use a crusher etc. to 30 m in advance.
It is desirable to use a crushed product crushed to m or less, preferably 10 mm or less.

The melting zone is for melting and plasticizing the crushed product of the resin with a coating film by a kneading element (kneading disk). The part that becomes this melting zone,
Alternatively, high-pressure water or high-temperature water may be added to the cylinder near the upstream end of the contact zone between the resin with a coating and the high-temperature / high-pressure water (or steam), which is the most upstream part of the next melt transport zone.・ At least one high-pressure steam inlet
One is provided. Then, a part which becomes a melting zone or a part which becomes a contact zone between the resin with a coating film and high temperature / high pressure water (or steam), wherein the high pressure water or high temperature
Upstream of high-pressure steam inlet (resin inlet with coating)
Is filled with water or steam that has been in a high temperature / high pressure state in the contact zone in a space formed by the cylinder and the screw, and therefore overcomes the pressure of the high temperature / high pressure water (or steam). A region filled with the molten resin, that is, a seal portion is formed so that the vapor pressure can be maintained, and thus, the reverse flow of the vapor to the resin feed side with the coating film can be prevented.

In the contact zone between the resin with a coating and the high temperature / high pressure water (or steam) which is the most upstream part of the melt transport zone, the resin containing the coating melted / plasticized in the melting zone is By contact with water or steam supplied from the inlet and brought into a high temperature / high pressure state to cause a hydrolysis reaction, or in the presence of a coating film decomposition accelerator such as the above-mentioned acid, alkali or salt, The coating film in the molten resin has a low molecular weight and becomes finer due to the decomposition reaction caused by contact with water or steam which is supplied from the inlet and has a high temperature and high pressure. The degree of miniaturization of the coating film in the contact zone depends on whether the resin containing the coating film extruded from the recycled resin discharge port (die) provided at the end portion of the cylinder is reused as a bumper material or the like. It is sufficient that the presence of is not harmful to the physical properties and the like, and it is preferably 25 μm or less.
More preferably, it should be 15 μm or less.

Further, in the method of the present invention, in order to efficiently carry out the decomposition reaction of the coating film in the contact zone, a holding region of steam by the supplied high-pressure water or high-temperature / high-pressure steam, that is, steam. It is necessary to provide a void portion based on the gas / liquid coexisting state of the water / melting resin system, and for that purpose, as described above, a space portion constituted by the cylinder and the screw in the melting zone or the contact zone. A molten resin filled area (sealing portion) is formed on the other side, while a downstream portion of the next devolatilization zone is provided from the downstream side (regenerated resin discharge port side) of a steam discharge hole described later provided in the contact zone. A region filled with the molten resin (sealing part) in the space formed by the cylinder and the screw, which is located on the upstream side of the exhaust port (vent) where the coating film is provided.
Are formed. The length of the filled area of these molten resins should be such that a resin seal portion that resists the pressure of the voids can be created for the above-mentioned purpose, and the type of coating resin supplied. It is determined by the amount of water, the amount of treatment, the injection amount of high-pressure water (or high-temperature / high-pressure steam), the temperature / pressure of the water (or steam) in the extruder, and the inner diameter of the cylinder of the extruder used. Although it cannot be said, usually, it is preferably 1 to 10 times the cylinder diameter.

The pressure of the water or water vapor supplied from the water or water vapor inlet is set in the contact zone in order to create a holding area for the steam by the high temperature / high pressure water or water vapor. It is preferable that the pressure is equal to or higher than the water vapor pressure. When injecting high-pressure water from the inlet, the temperature of the water is not particularly limited, but water at room temperature is convenient for handling. Then, the high-pressure water injected into the extruder is heated in the extruder and brought into a high temperature / high pressure state suitable for the decomposition of the coating film as described above.

Further, according to the present invention, in the region forming the void portion in the contact zone, the coating film present inside the molten resin is positively driven by the rotational driving of the screw (the resin and the void portion are combined). It is desirable to provide a surface renewal portion which is exposed to the boundary surface) and allows water or water vapor to actively permeate into the molten resin to increase the chance of contact with the coating film inside the resin.

By the way, the resin containing the coating film which has passed through the contact zone and is made fine to the desired degree contains water vapor or water, and as it is, a recycled resin discharge port (die) of the cylinder described later. If the resin is extruded from the die nozzle portion provided in, the resin may be in a foamed state and the strand may not be drawn. Therefore, in the extruder used in the method of the present invention, a devolatilization zone is provided on the downstream side of the contact zone of the melt transport zone, and at least one is provided in the cylinder at the location where the zone is formed. An exhaust port (vent) is provided. Then, the water in the resin is removed by discharging it from the exhaust port (vent) into the atmosphere or by vacuum-venting with a known vacuum device such as a Nash pump.

However, since only the volatile components such as water can be removed by the air vent from the exhaust port or the vacuum vent, the impurities are positively discharged together with the resin and the regenerated resin discharge port ( It is also possible to discharge in a foamed state from the die nozzle portion of the die and then wash with hot water. Therefore, the devolatilizing zone is not absolutely necessary for the screw configuration of the extruder used in the method of the present invention.

The final stage of the melt transport zone is the pressure boost zone. In this pressure rising zone, a die nozzle portion is provided at the recycled resin discharge port (die) at the terminal end thereof, and the molten resin devolatilized in the devolatilization zone, or
Depending on the purpose, extruded from the nozzle hole by compressing the molten resin that has not been devolatilized and containing sufficient moisture so as to overcome the resistance of the die nozzle portion and pass through the nozzle hole. Strands,
Alternatively, in the foamed state, the recycled resin discharge port (die)
Is released from. Therefore, the pressure in the boost zone is
Although it depends on the type and treatment amount of the coating resin supplied to the extruder, it is preferably about ^{2 to} 150 kg / cm ² G.

As described above, the resin with coating film supplied from the resin supply port with coating film into the extruder is rotated by the screw to drive the melt transport zone, that is, the contact zone, the devolatilization zone, While the coating film is refined to a level that can be used as a recycled material while sequentially moving in the pressure increasing zone, the coating film is kneaded and included in the molten resin, so that the coating film is contained in the molten resin. It is evenly and 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 it is desirable that the recycled molten resin is further cooled in a water-cooled water tank, cut by a pelletizer, and pelletized. The water-cooled water tank and the pelletizer that are normally 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 recycled molten resin is not essential, and it is discharged in a strand form from the recycled 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, the major ones of the operating parameters of the extruder in the method of the present invention, particularly the twin-screw type extruder having the screw structure as described above, will be described. The degree of decomposition and miniaturization of the coating film is determined by the temperature / pressure and residence time of the resin containing the coating film in the contact zone, exposing the coating film inside the resin to the surface where water (or water vapor) intervenes, or vice versa. Is determined by the ability of water (or water vapor) to permeate and disperse inside the resin and contact the coating film inside the resin.
Not only the reaction conditions (temperature and pressure) in the contact zone, but also the treated amount of the resin with a coating, the amount of water or steam supplied, the amount of a coating decomposition accelerator, the screw configuration, the screw rotation speed, etc. To give.

When the reaction temperature in the contact zone is lower than the melting point of the base resin supplied, the melting of the base resin in the contact zone is insufficient, resulting in the coating film and the base resin. Since the kneading with and becomes insufficient, the coating film inside the resin is exposed to the surface where water or water vapor intervenes, or
It is not preferable because the chance of water or water vapor penetrating into the resin and coming into contact with the coating film inside the resin decreases, and the decomposition reaction rate of the coating film decreases. When the reaction temperature in the contact zone exceeds the heat deterioration temperature of the base resin to be supplied, the coating resin is locally heated to a temperature not lower than the heat deterioration temperature of the base resin, Is deteriorated and the resulting resin cannot be used as a recycled material, which is not preferable.

On the other hand, in the present invention, as described above, the reaction pressure in the contact zone is set to the above-mentioned conditions so that a vapor / liquid coexisting state of water vapor / water-molten resin system can be created in the contact zone. Although it is desirable that the steam pressure be equivalent to the selected reaction temperature, steam /
The third component (for example, an inert gas such as nitrogen gas, argon gas, or helium gas) can be pressed into the contact zone as long as the gas-liquid coexisting state of the water-molten resin system is maintained. However, if the water vapor pressure is lower than the set reaction temperature, the decomposition reaction rate of the coating film will be slow, so that the coating film can be made as fine as desired to reuse the resin containing the coating film. It is not preferable because it cannot be converted. Further, when the reaction pressure in the contact zone is set higher than the steam pressure corresponding to the set reaction temperature, the pressure causes a vapor pressure holding region in the contact zone due to high temperature / high pressure water and / or steam. That is, in order to properly form a void portion based on a gas-liquid coexistence state, a portion upstream of the inlet of the high-pressure water or high-temperature / high-pressure steam, and the following steam discharge hole and the exhaust port Sealing with molten resin in the area between becomes insufficient,
Therefore, the resin containing the coating film is not efficiently contacted with hot water or water vapor, and the decomposition reaction rate of the coating film is lowered, which is not preferable.

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 brings the vapor pressure holding region formed by the high temperature and high pressure water and / or steam formed in the contact zone into a gas-liquid coexisting state, and maintains the water vapor pressure,
Therefore, the object is to maintain the temperature corresponding to the water vapor pressure, and thereby maintain the high temperature / high pressure state in the contact zone under constant conditions (temperature and pressure) suitable for the decomposition reaction of the coating film. . Therefore, the pressure adjusting mechanism is not particularly limited as long as it can achieve the above object, but the cylinder (which is located near the end of the contact zone on the upstream side of the devolatilization zone). It is composed of a steam discharge hole at an intermediate portion between the high-pressure water or high-temperature / high-pressure steam inlet and the exhaust port), a pipe connected to the steam discharge hole, and a pressure control valve provided in the pipe. Preferably.

Since the pressure adjusting mechanism is provided, excess water and steam existing in the extruder are discharged from the steam discharge hole to the outside of the system through the pipe, and therefore, fresh water or steam is constantly extruded. It will be supplied onboard. Then, the excess water or steam is partially or entirely kept in a hot water state until it passes through the pressure regulating valve, and in the contact zone which is a component soluble in the hot water. The decomposition product is discharged out of the system together with the hot water. As a result, the impurities contained in the recycled resin can be reduced, and the recombination of decomposed coating film components can be reduced.

The longer the residence time of the resin containing the coating film in the contact zone, that is, the decomposition reaction time of the coating film, the more the decomposition and miniaturization of the coating film progress. Therefore, the pressure / temperature of the resin containing the coating film in the contact zone, the supply amount of high-temperature / high-pressure water or steam, the cylinder diameter of the extruder, the screw configuration,
As long as the extruder is operated with constant operating parameters such as the screw length and the screw rotation speed, and in some cases other than these, the reaction time is the resin containing the coating film. Is proportional to the processing amount of. That is, the smaller the amount of the resin containing the coating film treated is, the more the decomposition reaction of the coating film progresses, and the finer the coating film becomes. However, this has an adverse effect from the viewpoint of the production efficiency of the recycled resin. The preferable range of the throughput of the resin containing the coating film in the method of the present invention is complicated by the above-mentioned various operating parameters and cannot be said to be unequivocal, but in reality, the cylinder diameter of 55 mmφ and L / D are practical. (Ratio of screw length to cylinder diameter) = 10 to 70 kg / in extruder of 60
H, especially 20 to 60 kg / H is desirable. And 55
In the case of a cylinder diameter other than mmφ, it is preferable that the processing amount is within the range defined by the formula 1.

[0037]

[Equation 1]

In the method of the present invention, in order to efficiently contact the resin containing the coating film in the contact zone with high temperature / high pressure water or steam, as described above, Creating a gas-liquid coexisting state of water-molten resin system,
It is necessary to properly form the voids that retain the vapor pressure of the high-temperature / high-pressure water or steam, and therefore the void ratio in the contact zone, that is, the proportion of the voids in the contact zone and It is necessary to optimize the water supply rate, that is, the supply amount of the high-pressure water or the high-temperature / high-pressure steam. The appropriate supply amount of the high-pressure water or high-temperature high-pressure steam is the type of the coating film or the base resin, the pressure / temperature of the resin containing the coating film in the contact zone, the pressure of the supplied water or steam, Although it depends on the temperature, etc., it is 0. 0 per 1 kg / H of the resin with a coating film (resin containing the coating film) to be treated in an extruder having a cylinder diameter of 55 mm.
It is preferably 1 to 0.8 kg / H. When the supply amount of the high-pressure water or the high-temperature / high-pressure steam is less than 0.1 kg / H, the decomposition reaction rate of the coating film in the contact zone becomes low, which is not preferable. On the contrary, when the supply amount of the high-pressure water or the high-temperature / high-pressure steam is more than 0.8 kg / H, the removal of water or steam from the coating resin in the devolatilization zone becomes insufficient, 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 pulled. In the method of the present invention, as described above, it is possible to inject high-pressure water and / or high-temperature / high-pressure steam from the high-pressure water or high-temperature / high-pressure steam inlet, but the coating film in the contact zone In order to improve the contact efficiency between the resin containing the resin and high-temperature / high-pressure water or steam, high-pressure water is injected from the injection port to generate steam in the contact zone, and steam / water vapor is generated in the contact zone. It is preferable to create a gas-liquid coexisting state of a water-molten resin system.

In the present invention, a pipe is connected to the above-mentioned inlet of high-pressure water or high-temperature / high-pressure steam, and the high-pressure water or high-temperature / high-pressure steam such as a metering pump is provided at the upstream end of the pipe. By providing a device for quantitatively supplying the above, it is possible to quantitatively feed the high-pressure water or the high-temperature / high-pressure steam into the contact zone in an appropriate amount described above.

Next, in the case of treating a resin containing a coating film which is difficult to hydrolyze such as urethane paint, the coating resin is brought into contact with high temperature / high pressure water or steam in the presence of the coating film decomposition accelerator. In this case, the amount of the coating film decomposition accelerating agent to be supplied is 0.01-per 1 kg / H of the coating resin.
An appropriate amount is about 10 g / H. 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 it is more than the appropriate amount, the coating film decomposition accelerator corrodes the base resin. However, neither of the above-mentioned coating film decomposition accelerators mixed in the recycled resin adversely affects the physical properties of the recycled resin, which is not preferable. As the method for adding the coating film decomposition accelerator, it is added to a crushed product of a resin containing a coating film and supplied from a resin supply port with a coating film at the cylinder upstream end of an extruder, or extruded from the injection port. A suitable method is to dissolve it in water supplied to the machine and supply it.

The screw rotation speed of the extruder depends on the throughput of the coating resin and the function of renewing the surface of the molten resin in the contact zone, that is, the decomposition reaction of the coating film contained in the molten resin in the contact zone. Influence. In the method of the present invention,
When an extruder having a cylinder diameter of 55 mmφ is used, 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, the 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 water or water vapor, or There is less opportunity for water vapor to penetrate into the resin and come into contact with the coating film inside the resin, reducing the so-called molten resin surface renewal function,
It is not preferable because the decomposition reaction rate of the coating film becomes low. When the screw rotation speed is more than 400 rpm, the output of the molten resin due to the rotational driving of the screw increases, and the amount of the resin with a coating film conveyed with respect to the amount of the high-pressure water or high-temperature / high-pressure steam supplied in the contact zone is increased. Increase, 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 sealing portion is shortened, and the sealing by the molten resin is weakened. On the other hand, the temperature of the base resin increases while the temperature decreases, and the base resin deteriorates. The screw rotation speed can be controlled by a known method, and for example, a method of using a variable speed motor as a driving device can be suitably adopted.

By the way, according to 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 formed by the cylinder and the screw in the cylinder is used. It is necessary to keep the temperature conditions constant. In other words, a heating mechanism is required to adjust the set temperature that varies depending on the temperature increase at the start and the type of coating resin 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 in the outer periphery of the cylinder in each block unit. desirable. As such a heat transfer device, a known device such as an electric heater wound around the outer circumference of the cylinder or a jacket structure can be used. For each block of the cylinder, a heating medium such as steam, or, if desired, or A cooling medium such as cooling water may be passed through the heat transfer device.

As described above, the extruder used in the method of the present invention, particularly preferably the meshing type co-rotating (or different direction) twin-screw type extruder, which is preferably used, is self-cleaning. Is a mechanical device with excellent temperature control, accurate temperature control, and excellent volatilizing ability and surface renewal function of molten resin, and (1) throughput of coated resin, screw configuration, screw rotation speed. It is possible to easily control the time during which the molten resin stays in the extruder by adjusting the above. (2) Since the screw is a segment type and the cylinder is a block type, the Change the screw configuration such as attaching a volatile zone or deleting it,
Easy to change the axial length of the kneading part, (3) Suitable for the decomposition reaction of the coating film depending on the type of coating resin to be treated by changing the set pressure of the attached pressure control valve It is also a machine with high flexibility in the production process, which has considerable flexibility in processing conditions, such as being able to easily hold different conditions (pressure and temperature).

In the method of the present invention, when the quality required for the recycled product is strict, an impact modifier or a compatibilizer is added during the kneading process in the extruder, or the recycled pellet is reused in the extruder. It is supplied to a resin supply port with a coating and passed through the extruder, or an automatic backwash filter for continuously removing a large coating is attached to the recycled resin discharge port (die) of the extruder if necessary. Needless to say, the quality of the recycled product can be made closer to that of the virgin material.

The present invention will now be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic flow chart showing an embodiment of 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, and 43 is a resin supply port with a coating attached to the cylinder 41. , 44 is a recycled resin discharge port attached to the cylinder 41, 45 is a high-pressure water (or steam) injection port attached to the cylinder 41, 46 is a steam discharge port attached to the cylinder 41, and 47 is attached to the cylinder 41. The exhaust port, and 48 are heat transfer devices.

Cylinder 4 of twin screw type extruder 4
A screw 42 is arranged in the screw 1, and the screw 42 is rotatably driven at one end thereof by a driving device not shown in FIG. A coating resin supply port 43 is provided on the drive unit side of the cylinder 41, and a recycled resin discharge port 44 is provided at the other end of the cylinder 41. The coating resin supply port 43 is provided with a coating film. When the resin is supplied, the resin is carried to the recycled resin discharge port 44 side as the screw rotates. 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 a coating advances in the space 420 formed by the cylinder 41 and the screw 42 in the cylinder 41. In the meantime, it is melted and maintained at a proper temperature.

The screw 42 comprises a solid transport zone 42
1. Melt zone 422 and melt transport zone 423, which further comprises contact zone 424, devolatilization zone 425 and pressurization zone 4
26, and at least a portion of the contact zone 424 is a surface renewal 427. Figure 1
The crushed product of the coated resin, which has been crushed to a proper particle size by a crusher not shown in FIG. 4 and supplied to the coated resin supply port 43, is in the melting zone 422, which is also shown in FIG. It is heated and melted by a kneading element (kneading disk) that is not heated, plasticized, and delivered to the contact zone 424 which is the most upstream part of the melt transport zone 423.

High pressure water (or water vapor) is present at the portion of the cylinder 41 located near the upstream end of the contact zone 424.
An inlet 45 is provided, which is connected to the tank 1 via a metering pump 2 by a pipe. A proper amount of water is in tank 1
Then, it enters the metering pump 2 through the pipe, is pressurized to a predetermined pressure by the metering pump 2, and is supplied again to the high-pressure water (or steam) inlet 45 through the pipe. Then, the water fed from the high-pressure water (or steam) inlet 45 to the contact zone 424 comes into contact with the molten resin containing the coating film, which is also sent to the contact zone 424, and is heated by the high-temperature molten resin, Part or all of it evaporates to generate water vapor. At the same time, the hydrolysis reaction of the coating film proceeds due to this contact, and the coating film has a low molecular weight and is refined to a desired level.

At a portion of the cylinder 41 located near the end of the contact zone 424, a steam discharge hole for discharging steam generated by evaporation of water fed from the high-pressure water (or steam) inlet 45 to the contact zone 424. 46 is provided, and the pressure regulating valve 3 is provided in the pipe connected thereto. A portion of the space 420 from a position near the end of the melting zone 422 to a position upstream of the high-pressure water (or steam) inlet 45 and near the upstream end of the contact zone 424. And a portion from a position which is on the downstream side of the water vapor discharge hole 46 and near the end of the contact zone 424 to a portion near the upstream end of the devolatilization zone (shown in FIG. 1). (Not provided), molten resin filled areas (sealing portions) 428 and 429 are formed so that high-temperature, high-pressure water or water vapor can be sealed based on the water fed to the contact zone 424.

As a result, the high-pressure water (or steam) inlet 45 is introduced into the contact zone 424.
Vapor pressure holding region 4 based on evaporation of water fed into
30 is secured. Therefore, in the contact zone 424, the coating film existing inside the resin is positively formed on the surface (of the water vapor layer and the resin layer) by the screw provided in the contact zone 424 and having a function mainly for kneading. The surface renewal portion 427 is formed so that water or water vapor is positively permeated into the molten resin to increase the chance of contact with the coating film existing inside the resin while being exposed to the boundary surface).

By securing the vapor pressure holding area 430 in the contact zone 424, the pressure regulating valve 3 is set to a pressure corresponding to the saturated vapor pressure at a temperature suitable for the decomposition reaction of the coating film, The pressure holding region 430 is maintained in a saturated vapor state, and the temperature itself is also maintained at a temperature corresponding to this saturated vapor pressure. The high temperature / high pressure state of the contact zone 424 is a constant temperature optimum for the decomposition reaction of the coating film. It is kept under pressure.

As described above, the molten resin containing the coating film which has been miniaturized to a desired level is used in the next devolatilization zone 425.
Be carried 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. The molten resin delivered to the devolatilization zone 425 contains water vapor or water that causes foaming at the time of discharging from the recycled resin discharge port 44, which will be described later, and the molten resin is depressurized by the vacuum device. The resin expands, and volatile components such as contained water are discharged from the exhaust port 47 to the vacuum device side.

The molten resin devolatilized in the devolatilization zone 425 is sent to the pressurization zone 426 which is the final stage of the screw construction 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 in the recycle resin discharge port 44. Has been. The molten resin delivered to the pressurizing zone 426 can be compressed under pressure and overcome the resistance of the die nozzle portion to pass through the nozzle hole of the die nozzle portion (also not shown in FIG. 1). Sufficient pressure is applied, the resin is extruded from the nozzle hole, and discharged from the recycled resin discharge port 44 in a strand shape.

The coating film that has passed through the contact zone 424 and is made fine to a desired level is rotated by the screw 42 to drive the devolatilization zone 425 and the pressurization zone 42.
While advancing through 6, it is kneaded and included in the molten resin. As a result, the recycled resin, in which the coating film that has been miniaturized to a level usable as a recycled material is uniformly finely dispersed in the base resin, is discharged from the recycled resin discharge port 44 in the form of a strand.

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

[0056]

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, the surface smoothness and mechanical properties of the pellets obtained when a material not containing a coating film (crushed bumper molded product before coating) was used as a raw material (Comparative Example 1) The measurement results of the physical properties were used as blanks, and the measurement results of the surface smoothness and mechanical properties of the pellets obtained in each Example and Comparative Example (excluding Comparative Example 1) were expressed as a relative comparison with the blank. That is, the measurement results of each Example and Comparative Example in the case where the blank value was made good were compared with the blank value, and evaluated in three grades of "good / somewhat bad / bad".
As the mechanical properties, the tensile yield strength, tensile elongation at break, bending strength, flexural modulus, Izod impact strength (-30 ° C) and embrittlement temperature were measured by the test methods shown in Table 1. .

Example 1 With the cylinder structure and screw structure shown in FIG. 1, the cylinder inner diameter (D) was 55 mmφ, and the axial distance was 46.
Rotation in the same direction with 0 mm and a screw length of 44D 2
Using a screw-screw extruder 4, a raw material (a crushed product of polypropylene bumper waste containing ethylene-propylene rubber, alkyd-melamine coating, average particle diameter 8 mm) is supplied from a resin supply port 43 with a coating of the extruder 4. 25 kg / H
It was supplied at a rate of. Then, from the high-pressure water (or steam) inlet 45, water is supplied at a rate of 8.4 kg / H,
The cylinder set temperature is set to 220 ° C. in each of the melting zone 422, the contact zone 424, the devolatilization zone 425, and the pressurization zone 426 in the cylinder 41, and the pressure adjusting valve 3 is adjusted to adjust the internal gas phase pressure to 10 ° C. ~ 1
It was kept at ² kg / cm ² G. When the twin screw type extruder 4 was operated with the rotation speed of the screw 42 set to 300 rpm, the average residence time of the raw material in the cylinder 41 was about 220 seconds, and the raw resin was discharged from the nozzle portion of the recycled resin discharge port 44 at the tip to the strand. was gotten. 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. The evaluation of the measurement results was good in terms of surface smoothness and mechanical properties. The measurement results of mechanical properties were as shown in Table 1.

Example 2 Water 8.4 kg / from high pressure water (or steam) inlet 45
Replace with H and add 0.1 wt% sodium hydroxide aqueous solution to 8.
Dry pellets were produced in the same manner as in Example 1 except that the amount was 4 kg / H (the amount of sodium hydroxide was 336 ppm with respect to the resin with coating film), and the surface smoothness and mechanical properties were improved. It was measured. The evaluation of the measurement results was good in terms of surface smoothness and mechanical properties. The results of measurement of mechanical properties are as shown in Table 1, and in particular, the tensile elongation at break is remarkable as compared with the case where only water is supplied from the high pressure water (or steam) inlet 45 (Example 1). Was excellent.

Comparative Examples 1 and 2 In Comparative Example 1, as a blank test, a crushed product of polypropylene bumper waste material containing the raw material ethylene-propylene rubber in Example 1 (alkyd-melamine coating, average particle size 8 mm) A material that does not contain a coating (crushed pre-painted bumper molded product, average particle size 8 m
m), and in Comparative Example 2, dry pellets were prepared in the same manner as in Example 1 except that neither water nor steam was supplied from the high-pressure water (or steam) inlet 45. It was manufactured and surface smoothness and mechanical properties were measured. Table 1 shows the measurement results of mechanical properties, and Table 2 shows the evaluation of the measurement results of surface smoothness and mechanical properties.

[0061]

[Table 1]

[0062]

[Table 2]

Comparative Example 3 In the co-rotating twin-screw extruder 4 shown in FIG. 1, except that the pressure adjusting valve 3 was not attached and the pressure was opened to the atmosphere.
Dry pellets were produced in the same manner as in Example 1. It was difficult to maintain the resin temperature and internal gas phase pressure in the twin-screw extruder 4 under constant conditions, and stable continuous operation of the twin-screw extruder 4 was not possible. And, the mechanical properties of the obtained dried pellets were considerably varied, the evaluation of the measurement results of the surface smoothness and the mechanical properties, and the measurement result of the embrittlement temperature among the mechanical properties are shown in Table 3. It was as shown in.

Comparative Examples 4 to 8 Among various operating conditions in the twin screw type extruder 4,
Dry pellets were produced in the same manner as in Example 1 except that the reaction pressure, the amount of raw material treated, the screw constitution, the screw length forming the contact zone and the screw rotation number were changed to the conditions shown in Table 3, respectively. The surface smoothness and mechanical properties were measured. Table 3 shows the evaluation results of the measurement results and the measurement results of the embrittlement temperature among the mechanical properties.

[0065]

[Table 3]

[0066]

As described above in detail, in the method and apparatus for recycling a resin with a coating film of the present invention, a molten coating film in an extruder equipped with a pressure adjusting mechanism, particularly a twin screw type extruder. Conventionally known because the coated resin is contacted with high-temperature / high-pressure water or water vapor under constant temperature / pressure conditions to decompose / fine-fine the coating film and uniformly finely disperse it in the resin and extrude from the extruder. In the method of regenerating a resin with a coating by hydrolyzing and refining the coating in a conventional autoclave, the production efficiency of the recycled material is reduced by the batch treatment and the coating of the coating into the resin is based on the static hydrolysis of the coating. Solves problems such as inadequate fine dispersion ability and variation in physical properties of reclaimed resin due to instability of operation in reclaiming method of resin with coating film by hydrolysis of coating film in conventionally known extruder The processing conditions and Continuous and in step a simple manner,
The coated resin can be stably regenerated. And
When a bumper is manufactured using the recycled product thus obtained, the appearance (surface smoothness) and physical properties of the virgin material are not significantly deteriorated.

[Brief description of drawings]

FIG. 1 is a schematic flow chart showing a preferred embodiment of a method for continuously regenerating a coated resin according to the present invention.

[Explanation of symbols]

 1 Tank 2 Metering Pump 3 Pressure Adjustment Valve 4 Twin Screw Extruder 41 Cylinder 42 Screw 43 Resin Supply Port with Coating Film 44 Recycled Resin Discharge Port 45 High Pressure Water (or Water Vapor) Injection Port 46 Water Vapor Discharge Hole 47 Exhaust Port 48 Transmission Heater 420 Space part 421 Solid transport zone 422 Melt zone 423 Melt transport zone 424 Contact zone 425 Devolatilization zone 426 Pressure rising zone 427 Surface renewal part 428 Melt resin full area 429 Molten resin full area 430 Vapor pressure retention area

Claims (3)

[Claims] 1. A method in which a molten resin with a coating film is brought into contact with high-temperature and high-pressure water and / or steam in an extruder to finely disperse the coating film in the molten resin and to regenerate it,
A method for continuously regenerating a resin with a coating film, comprising providing a pressure adjusting mechanism in a contact zone between the resin with a coating film and water and / or steam at high temperature and high pressure. 2. The continuous coating resin according to claim 1, wherein the molten coating resin is brought into contact with high-temperature / high-pressure water and / or steam in the presence of a coating decomposition accelerator. How to play. (1) Resin supply port with coating film (2) Solid transport zone (3) Melting zone (4) Melt transport zone (5) Recycled resin discharge port (die), cylinder (3) At least one high-pressure water or water vapor inlet and at least one exhaust port (vent) are provided in the melting zone and / or (4) the melt transport zone, and the inlet and outlet of the cylinder are connected to each other. The intermediate portion is provided with a pressure adjusting mechanism including a water vapor discharge hole, a pipe connected thereto, and a pressure adjusting valve provided in the pipe, and the upstream side of the injection port of the cylinder (coating film). A molten resin for enclosing water or water vapor that has been injected into a high temperature / high pressure state at a location on the resin supply port side) and a location between the water vapor discharge hole of the cylinder and the exhaust port. That the sealing portion is formed, also, between the seal portion, the continuous playback apparatus of the film-coated resin using a biaxial extruder having a screw shape which serves mainly composed of kneading.