JPH0959422A - Method for recovering inorganic filler from plastic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering an inorganic filler from a plastic material, whereby the inorganic filler can be recycled as an effectively recyclable one. SOLUTION: The plastic matrix of an inorganic-filler-filled plastic material is wet-decomposed with an oxidizing agent. In the wet decomposition, the matrix can be decomposed into a low-molecular substance at a temperature at which the inorganic filler is not thermally deteriorated. By subjecting the product of the wet oxidation to solid/liquid separation, the filler can be recovered from the plastic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a plastic material, and more particularly, to recovering an inorganic filler from a plastic material capable of treating the plastic material and recovering the inorganic filler while preventing its deterioration. Regarding the method.

[0002]

2. Description of the Related Art Plastic materials containing inorganic fillers are
Its applications range from heat insulating materials for spacecraft to automobile parts, office automation equipment parts, precision equipment parts, home appliances, etc. At present, such used plastic materials are crushed and then disposed of in landfill, and the valuable inorganic filler is also discarded without being reused. For this reason,
It is desired to develop a method for collecting and regenerating these inorganic fillers.

As a method for recovering an inorganic filler from a plastic material, Japanese Patent Application Laid-Open No. 52-84261 discloses a waste treatment method for glass fiber reinforced thermosetting resin.

[0004]

However, according to this method, a plastic matrix of 400-60 is used.
Since the inorganic filler is thermally decomposed at a high temperature of 0 ° C., it is difficult to reuse the inorganic filler.

Therefore, an object of the present invention is to provide a method of recovering an inorganic filler from a plastic material, which enables effective recovery of the inorganic filler.

[0006]

In order to solve the above-mentioned technical problems, the inventors of the present invention compare the thermal decomposition method and the like by oxidatively decomposing a plastic matrix of a plastic material containing an inorganic filler by a wet method. Then, the present invention has been completed by focusing on the fact that the plastic matrix can be decomposed with high efficiency by the treatment at a low temperature. That is, the present invention is a method for recovering an inorganic filler from a plastic material, which comprises subjecting a plastic matrix of the plastic material containing the inorganic filler to wet decomposition using an oxidizing agent.

The present invention is also characterized in that the wet decomposition is carried out in water or high-concentration steam. Further, the present invention is characterized in that the plastic material is previously crushed or crushed. Further, the present invention is characterized in that the plastic matrix is made of or contains a thermosetting resin. Further, the present invention is characterized in that the thermosetting resin is a urethane resin. Further, the present invention is characterized in that the plastic matrix contains any of a chlorine-containing resin, a nitrogen-containing resin, and a sulfur-containing resin. Further, the present invention is characterized in that the oxidizing agent is hydrogen peroxide, ozone and / or oxygen. Also, the present invention
The plastic matrix is a foamed resin. Further, the present invention is characterized in that the inorganic filler is potassium titanate whiskers.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The wet decomposition of the present invention is a wet process, in which an oxidant is used to break the chemical bonds inside the resin constituting the plastic matrix, so that the matrix resin may be thermoplastic or thermosetting, and may be inorganic-filled. The matrix can be decomposed and made into low molecular weight compounds within a temperature range where the material does not decompose or deteriorate. Wet in the present invention means in the presence of liquid water. For example, the plastic matrix can be more efficiently oxidized and decomposed by being performed in water or high-concentration steam. The high-concentration water vapor is in water vapor and means a state in which the water vapor is liquefied on the surface of the plastic material.

The plastic material targeted by the present invention is
Although not particularly limited, it is usually a waste material, a molded end material, a defective product, a defective material, or the like. The plastic material has a plastic matrix and an inorganic filler, and may further contain additives and the like. The plastic matrix is made of plastic and is a dispersion medium for the inorganic filler.
The plastics that make up the plastic matrix are
Not only one type, but two or more types may be used. That is, the plastic matrix may be in the form of a polymer blend.

The type of plastic used for the plastic matrix is not particularly limited, but the present invention is useful when the plastic matrix is a thermosetting resin. When the thermosetting resin is a plastic matrix, it usually requires a high temperature for the thermal decomposition of the matrix, and deterioration of the inorganic filler is unavoidable. Since the chemical bond is broken, the matrix can be decomposed at a temperature at which the inorganic filler is not thermally deteriorated.
Examples of the thermosetting resin include urethane resin, phenol resin, urea resin, melamine resin, xylene resin, unsaturated polyester resin, alkyd resin, epoxy resin, and polyimide resin. In particular, a urethane resin containing an inorganic filler used for an automobile urethane bamba or the like has a large member and is produced in a large amount, so that a large amount of treatment is required, and high efficiency as in the present invention is obtained. It is useful to apply the method of recovering the inorganic filler by means of effective use of resources (inorganic filler).

The inorganic filler is efficiently added from the matrix,
Moreover, in order to perform sufficient separation, various solid-liquid separation methods such as filtration and specific gravity selection can be used, but what is necessary at that time is to make the matrix a sufficiently low-viscosity liquid. For that purpose, even in the case of a thermoplastic resin, only thermal melting is not sufficient, and decomposition of the resin and reduction of the molecular weight thereof are required.

The present invention is also useful when the plastic matrix is a chlorine-containing resin such as a vinyl chloride resin, a nitrogen-containing resin such as a urethane resin, or a sulfur-containing resin. In other words, these resins generate acidic gas such as chlorine gas, hydrogen chloride gas, nitrogen oxide gas, sulfuric acid gas, etc., which have strong oxidizing power, in the thermal decomposition method or dry combustion method, so that the containers and piping equipment and heat It is difficult to handle because the decomposition catalyst etc. is severely damaged. However, in the present invention, since it decomposes in a wet state, that is, in the presence of water in a liquid state,
A basic substance such as sodium hydroxide capable of neutralizing an acidic gas such as hydrogen chloride gas can be mixed in advance. Therefore, the exhaust gas treatment of hydrogen chloride gas can be made efficient without damaging the equipment. To neutralize the acidic gas by adding the basic substance, for example, solid sodium hydroxide or sodium hydroxide solution is added to the reaction tank in advance or during the treatment. In the present invention, for example, as the chlorine-containing resin, vinyl chloride resin, vinyl chloride vinyl acetate copolymer resin, chlorinated polyethylene resin, vinylidene chloride resin, vinyl acetate resin and the like, and as the nitrogen-containing resin, urethane resin, polyamide resin Examples of the polyimide resin and the like, and examples of the sulfur-containing resin include polysulfone and polyphenylene sulfide.

The form of the plastic matrix is preferably foamed, crushed or crushed. With these forms, the surface area of the plastic matrix is large, and the treatment with the oxidizing agent is efficiently performed. The size of the crushed or crushed plastic matrix is not particularly limited, but 1 mm square or more and 2 mm square or less is preferable from the viewpoint of the efficiency of the oxidation treatment. Further, particularly when the plastic matrix is a foamed resin, the volume of the matrix can be greatly reduced by the present invention, and as a result, the efficiency of the subsequent recovery treatment of the inorganic filler can be greatly improved. You can Examples of the foam resin include foam polystyrene resin, foam phenol resin, foam urea resin, foam epoxy resin, foam nylon, foam polyurethane resin, foam polyethylene resin, foam polypropylene resin, foam vinyl chloride resin, foam ethylene vinyl acetate copolymer. Etc. can be mentioned.

The inorganic filler of the present invention is mainly composed of an inorganic substance, and may be of any kind, material or form as long as it can be contained in the plastic matrix. For example, as the material of the inorganic filler, ceramics such as potassium titanate, oxides such as silicon oxide, nitrides such as aluminum nitride, carbides, carbonitrides, etc., natural materials such as glass, metal, mica, quartz, clay, etc. The thing etc. can be mentioned. The form of the inorganic filler may be granular, powdery, fibrous, flaky, or the like. If it is an inorganic filler, the action in the plastic material is mechanical strength, barrier properties, impact resistance, elastic modulus, abrasion resistance, expansion coefficient suppression, heat resistance, molding workability, decorativeness, weight increase, It does not matter what kind of action such as coloring is, or not. Specific examples of such an inorganic filler include whiskers such as ceramic whiskers, glass fibers, viscous plates, and viscous particles. When the present invention is applied to a ceramic inorganic filler whose crystal structure is changed by a high temperature, the ceramic filler can be recovered without changing the crystal structure because it can be processed at a low temperature. It is useful in terms. In particular, according to the present invention, the potassium titanate whiskers filled for the purpose of improving the mechanical strength can be recovered from the plastic material without changing the crystal structure.

The oxidizing agent in the present invention can be used without particular limitation. Specifically, for example, oxygen in air, oxygen in water, ozone, hydrogen peroxide, and the like. The use conditions of the oxidizing agent are not uniform depending on the type of the plastic matrix and the oxidizing agent. For example, when the urethane resin is treated with hydrogen peroxide, it is preferable to perform the wet oxidation treatment at a temperature of 220 to 370 ° C. for 5 minutes or more at a pressure higher than that required to maintain the liquid phase.

After the plastic material is wet-oxidized, a wet oxide (solid content) is recovered by washing and filtering the treatment liquid with water. Since it is a wet oxidation method, the resin decomposition liquid has a sufficiently low viscosity, and is easily separated from the recovered filler. Therefore, the collected solids do not have enough resin to be reused.

Degradation of the recovered inorganic filler, particularly thermal degradation, is carried out by observing its shape and size by electron microscope (SEM) observation, and by confirming the crystal structure by X-ray diffraction. be able to.
In addition, the content of the inorganic substance in the wet-oxidized product can be calculated by measuring the change in thermogravimetry.

[0018]

Embodiments of the present invention will be specifically described below. As a plastic material, 1 fibrous potassium titanate (K ₂ O · 8TiO ₂ ) whiskers
Using urethane resin (non-foaming) containing 8 wt%, Examples 1 to 3 shown in Table 1 (treatment temperature 250 ° C., 300 ° C., 33
At 0 ° C., a potassium titanate whisker recovery experiment was conducted. In addition, as comparative examples, the same urethane resin was used without wet oxidation treatment (Comparative Example 1), treatment temperature of 100 ° C. (Comparative Example 2), treatment temperature of 200 ° C.
(Comparative Example 3) was used. For Comparative Examples 2 and 3, a recovery test was performed under the same conditions as in the Examples. In addition,
Urethane resin is 1 mm in advance with a cutter type crusher.
It is crushed to 2 mm square.

In the recovery experiment, an autoclave (30 ml) was used as a reaction vessel, 50 mg of the above-mentioned urethane resin and 20 ml of hydrogen peroxide solution (15 vol%) were mixed, and the mixture was stirred for 60 minutes under the temperature conditions shown in Table 1, The wet oxidation treatment was performed under a pressure condition in which liquid water was present. After processing,
The obtained wet oxide was filtered, the thermogravimetric change was measured for the solid content collected by filtration, and the inorganic content in the solid content was calculated from the weight ratio at 110 ° C. and 1000 ° C. (FIG. 1).
reference). It should be noted that the filtration of the wet oxide could be efficiently performed because the plastic matrix was sufficiently decomposed and made into low molecular weight to have low viscosity. The results are shown in Table 1. It should be noted that 110 ° C. is the temperature at which the water adhering to the solid content evaporates, and the weight at this temperature is the total weight of the organic substance and the inorganic substance. The weight at 1000 ° C. is the temperature at which organic substances are completely decomposed and gasified.
The weight at 00 ° C is the weight of the inorganic substance. Further, the solid content of Example 1 was subjected to SEM observation and X-ray diffraction.

[0020]

[Table 1] As shown in the results of this table, regarding the inorganic content of the solid content of the wet oxidation treatments of Examples 1 to 3, the treatment temperature (2
Approximately 90 regardless of 50 ℃, 300 ℃, 330 ℃)
%Met. On the other hand, for Comparative Examples 1 to 3, 1
Only a low inorganic content of 8 to 58% was obtained. Therefore, in recovering the titanate whiskers from the urethane resin, it was confirmed that the solid content having a high inorganic content can be obtained by the wet oxidation treatment at a temperature of 250 ° C to 330 ° C. Further, since the solid content obtained by the wet oxidation treatment in this temperature range has a high inorganic filler content, it can be reused as it is.

In FIG. 1, Example 1 and Comparative Examples 1 to 3 are shown.
The graph of the thermogravimetric change of is shown. According to this graph,
In Example 1, in the range of 110 ° C. to 1000 ° C., about 1
It shows a 0% weight change (weight reduction), and it is clear that the amount of organic substances contained in the wet oxide is small, that is, the urethane resin was well decomposed and the inorganic filler was efficiently recovered. is there. On the other hand, Comparative Examples 1 and 2
At the processing temperature of 20
The urethane resin of Comparative Example 3 at 0 ° C. showed no significant weight loss as in Comparative Examples 1 and 2, but exhibited a large weight change as compared with Example 1.

FIG. 2 shows a photograph of the filtered wet oxide obtained in Example 1, taken by SEM. According to the SEM observation, the observed titanate whiskers have the same fibrous shape and size as before being filled in the urethane resin, and the shape of the potassium titanate whiskers is destroyed even at the treatment temperature of 250 ° C. It was possible to confirm that they could be collected without any problems.

FIG. 3 shows the X-ray diffraction pattern of the filtered wet oxide obtained in Example 1. In this figure, all the diffraction peaks marked with ● (peak intensity of 10 or more) are potassium titanate (K ₂ O.8).
It was a diffraction peak due to TiO ₂ ). That is, it could be confirmed that the wet oxidation treatment did not change to another crystal structure such as K ₂ O.6TiO ₂ .

From these results, it was confirmed that according to this example, the potassium titanate whiskers can be efficiently recovered from the urethane resin without being thermally deteriorated.

[0025]

According to this method, since the plastic matrix can be decomposed at a lower temperature than the thermal decomposition method or the like, the inorganic filler can be recovered without being thermally deteriorated.

[Brief description of drawings]

FIG. 1 is a diagram showing thermogravimetric changes of wet oxides of Example 1 of the present invention and Comparative Examples 1 to 3.

FIG. 2 is a view showing an electron microscope photograph in which the wet oxide of Example 1 is magnified 2900 times.

FIG. 3 is a diagram showing an X-ray diffraction pattern of the wet oxide of Example 1.

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Claims (9)

[Claims] 1. A method for recovering an inorganic filler from a plastic material, which comprises subjecting a plastic matrix of the plastic material containing the inorganic filler to wet decomposition using an oxidizing agent. 2. The method for recovering an inorganic filler from a plastic material according to claim 1, wherein the wet decomposition is carried out in water or high-concentration steam. 3. The method for recovering an inorganic filler from a plastic material according to claim 1, wherein the plastic material is crushed or crushed in advance. 4. The method for recovering an inorganic filler from a plastic material according to claim 1, wherein the plastic matrix is made of a thermosetting resin or contains the thermosetting resin. 5. The method for recovering an inorganic filler from a plastic material according to claim 4, wherein the thermosetting resin is a urethane resin. 6. The method for recovering an inorganic filler from a plastic material according to claim 1, wherein the plastic matrix contains any one of chlorine-containing resin, nitrogen-containing resin and sulfur-containing resin. 7. The method for recovering an inorganic filler from a plastic material according to claim 1, wherein the plastic matrix is a foamed resin. 8. The oxidizing agent is hydrogen peroxide, ozone and / or
Alternatively, it is oxygen, and the method for recovering the inorganic filler from the plastic material according to claim 1. 9. The method of recovering an inorganic filler from a plastic material according to claim 1, wherein the inorganic filler is potassium titanate whiskers.