JP4455526B2 - Resin material recovery method and recovery device - Google Patents

Description

The present invention relates to a resin separation method, and more particularly, to a method and an apparatus for separating and recovering a urethane decomposition product and a thermoplastic resin from a mixture containing a urethane resin and a thermoplastic resin.

  The problem of waste disposal has become increasingly serious in recent years, and dioxin generation during incineration, landfill reduction, etc. are widely taken up as social problems. Examples of major sources of such waste include container and packaging materials, building materials, automobiles, home appliances, and the like. Particularly, the amount of used home appliances discarded from homes is enormous.

  Large-scale and large-scale wastes include refrigerators, building materials, cushion materials, and the like, and urethane resins are frequently used. For this reason, there is an increasing demand for reuse and recycling of this urethane resin. However, since this urethane resin is a thermosetting resin having a three-dimensional network structure, it is difficult to recycle it. It has been disposed of.

  Conventionally, as a recycling method for these home appliances, used home appliances are finely crushed and then classified into metals, non-ferrous metals, plastics, etc. through wind sorting, magnetic sorting, eddy current sorting, etc., and reused. It is being broken. For example, as a resource recycling method for a refrigerator, it is known that the refrigerator is crushed and plastic and metal are separated by a method such as wind sorting (see, for example, Patent Document 1).

Moreover, as a method of chemically treating and recycling a urethane resin, a method is described in which the urethane resin is decomposed with monoethanolamine and then distilled to isolate a polyol and a polyamine (see Patent Document 2). . In addition, a method in which a urethane resin is decomposed with an alkanolamine and a polyol and used as an adhesion assistant is known (see Patent Document 3). Moreover, when decomposing | disassembling a urethane resin, the method of adding a thermoplastic resin and inorganic particle | grains and solidifying a urethane decomposition product and using as a resin raw material is known (refer patent document 4).
JP 2001-259529 A Japanese Patent Publication No.42-10634 JP-A-6-184513 JP 2004-115658 A

  As mentioned above, in the conventional recycling system, it is considered that the method of sorting and recycling waste shredder dust by wind force is effective, but when waste containing urethane resin is separated by this method and reused In addition, as a resin component to be recovered, it is practically important to obtain a resin material such as a urethane resin having the highest possible purity. However, resin materials such as expanded polystyrene other than urethane resin are also used for waste, particularly home appliance waste, and it is difficult to separate polyurethane, particularly expanded polyurethane resin and expanded polystyrene, in the wind sorting.

  In other words, in addition to the urethane foam resin, most of the lightweight materials obtained by wind sorting, such as foamed polystyrene and thin thermoplastic resin sheets, are mixed as impurities. For this reason, when recycling what was collected as a lightweight thing as urethane resin, the impurity becomes a problem.

  In addition, it is conceivable to separate these lightweight materials by (1) specific gravity separation, (2) solvent dissolution separation, etc., but the specific gravity separation of (1) is practically impossible because there is almost no difference in specific gravity between urethane and lightweight materials. In addition, in the solvent dissolution separation of (2), it is necessary to separate the solvent added in order to dissolve the specific resin, which is very troublesome.

  On the other hand, from the standpoint of recycling the urethane resin, the inclusion of this foreign substance may cause a decrease in resin strength, which is not preferable from the viewpoint of quality control. Patent Document 4 describes a method of adding a thermoplastic resin or inorganic particles to solidify a urethane decomposition product when decomposing a urethane resin, and using it as a resin raw material. Has been shown to be inferior.

The present invention has been made in view of such problems, and efficiently separates a urethane resin and a thermoplastic resin from a mixture containing a lightweight urethane resin and a lightweight thermoplastic resin obtained by wind sorting or the like. It is an object to provide a method and apparatus.

  In order to solve the above-described problem, according to one aspect of the present invention, a decomposition agent is reacted with a resin mixture containing a urethane resin and a thermoplastic resin to lower the molecular weight of the urethane resin, and a urethane decomposition product having a softening point of 50 ° C. or higher. The first step of obtaining a decomposition mixture containing the urethane, the second step of pulverizing the decomposition mixture containing the urethane decomposition product obtained in the first step, and the third step of separating the urethane decomposition product and the thermoplastic resin, The decomposition product and the thermoplastic resin are separated and recovered.

According to another aspect, a mechanism for obtaining a mixture containing a urethane decomposition product having a softening point of 50 ° C. or higher by reacting a decomposition agent with a mixture containing a urethane resin and a thermoplastic resin to lower the molecular weight of the urethane resin. This is a resin material recovery device having a mechanism for pulverizing a mixture containing a urethane decomposition product obtained in one step and a mechanism for separating a urethane decomposition product and a thermoplastic resin.

According to the method of the present invention, the urethane resin and the thermoplastic resin can be efficiently separated by a simple method, and a recovered resin material suitable for recycling can be obtained.
Moreover, according to the apparatus of this invention, a urethane resin and a thermoplastic resin can be separated efficiently, without using a large installation.

  As described above, it is extremely difficult to separate a mixture of, for example, foamed polyurethane, foamed polystyrene, or polyethylene sheet contained in waste by wind sorting. It is very difficult to separate by wind sorting because it has little specific gravity difference or is swept away by wind. In the present invention, a part of the urethane resin is chemically decomposed to obtain a urethane decomposition product having a softening point of 50 ° C. or higher, so that only this urethane decomposition product is easily pulverized. When pulverized thereafter, the urethane decomposition product becomes finer, and the thermoplastic resin is hardly pulverized, so it remains in its original shape. For this reason, it can sort by the sifting which sorts with the magnitude | size of particle | grains, or the wind-power sorting which adjusted the air volume. The present invention has been made paying attention to this point.

  The recovery method of the present invention includes a first step of obtaining a mixture containing a urethane decomposition product having a softening point of 50 ° C. or more by reacting a decomposition agent with a mixture containing a urethane resin and a thermoplastic resin to lower the molecular weight of the urethane resin. It includes a second step of pulverizing the mixture containing the urethane decomposition product obtained in the first step, and a third step of separating the urethane decomposition product and the thermoplastic resin.

  The recovery apparatus according to the present invention includes a decomposition mechanism for reducing a molecular weight of a urethane resin by reacting a mixture containing a urethane resin and a thermoplastic resin with a decomposing agent to obtain a mixture containing a urethane decomposition product having a softening point of 50 ° C. or higher, and this mechanism. And a mechanism for pulverizing the mixture containing the urethane decomposition product obtained by the above, and a mechanism for separating the pulverized urethane decomposition product and the thermoplastic resin.

[First Embodiment: Method for Collecting Resin Material]
Hereinafter, the recovery method of the present invention will be described in detail.
(First step: resin decomposition step)
The resin mixture applied in the present invention contains a urethane resin and a thermoplastic resin. Typical examples of the thermoplastic resin include sheets of foamed polystyrene resin, foamed polyethylene, polyethylene, and polypropylene. Typical examples of these mixtures include shredder dust for automobiles and home appliances, and among them, it can be preferably applied to shredder dust for home appliances, particularly refrigerators. This is because the shredder dust of the refrigerator contains not only a urethane foam resin but also lightweight materials such as a foamed polystyrene and a polyethylene sheet, which are difficult to separate by a normal method.

  Preferably, prior to entering this process, heavy materials such as metal, sand and stone, non-foamed thermoplastic resin, etc. are sorted by conventional wind sorting, etc., and urethane resin (foam) and expanded polystyrene, etc. It is good to make a mixture of thermoplastic lightweight materials.

  First, in the first step, a decomposing agent that decomposes the urethane resin is dispersed in the entire mixture, and only the urethane resin is reduced in molecular weight by a device that is heated (details will be described later). As a result, the urethane resin becomes a urethane decomposed product (low molecular weight product of urethane resin) that is easily pulverized, and since the pulverization behavior is different from that of other resins, it becomes easy to select after pulverization.

  Examples of the urethane resin decomposition method include a chemical decomposition method, a hydrolysis method, and a thermal decomposition method using a decomposition agent. In the present invention, a chemical decomposition method using a decomposition agent is preferably used. In the hydrolysis method and the thermal decomposition method, since the decomposition reaction of urethane becomes a high temperature, the thermoplastic resin is also thermally decomposed to have a low molecular weight and become brittle, making separation difficult. Examples of the decomposing agent used in the chemical decomposition method include an amine compound, a polyol compound and an alkali metal alcoholate thereof, and examples of usage forms include an amine compound alone, a polyol compound or a polyol metal alcoholate alone, and an amine. And a mixture of the compound and a polyol compound or a metal alcoholate of a polyol. The present invention is suitable for application of a resin decomposition product by a decomposition method using an amine compound or a polyol compound, and in particular, in the case of decomposition using an amine compound (using an amine compound alone or a mixture of an amine compound and a polyol compound). Is suitable. Examples of the amine compound used include monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, propanediamine, 2-ethylhexylamine, isopropanolamine, and 2- (2-aminoethylamino) ethanol. 2-amino-2-hydroxymethyl-1,3-propanediol, ethylaminoethanol, aminobutanol, n-propylamine, di-n-propylamine, n-amylamine, isobutylamine, methyldiethylamine, cyclohexylamine, piperazine , Piperidine, aniline, toluidine, benzylamine, phenylenediamine, xylylenediamine, chloroaniline, pyridine, picoline, N-methylmorpholine Ethylmorpholine, pyrazole and the like. Examples of the polyol compound include ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, Examples include glycerin and polyethylene glycol.

  A urethane decomposition product is obtained by mixing such a decomposition agent with a urethane resin and heating to a temperature in the range of about 100 to 300 ° C. as necessary. The mixing ratio of the urethane resin and the decomposing agent varies depending on the type of decomposing agent and the decomposing conditions, but is generally preferably urethane resin / decomposing agent = 8/1 to 100/1. The apparatus for decomposing the urethane resin is not particularly limited, but it is desirable to use an apparatus capable of simultaneously performing heat-kneading compression such as an extruder. Use of such an apparatus is preferable because the reaction time can be controlled and the molecular weight of the resulting urethane decomposition product can be made uniform. In an apparatus that decomposes over time, such as a batch type, the molecular weight distribution becomes wide because there is a difference between the one that starts decomposition first and the one that starts decomposition later. In such a case, some low molecular components lower the softening point and make pulverization difficult, which is not preferable.

  By this step, the urethane resin contained in the resin mixture is decomposed to such an extent that the softening point is 50 ° C. or higher. The softening point of the urethane resin can be adjusted to this range by controlling the conditions such as the composition of the urethane resin material used as a raw material, the type and amount of the decomposing agent, the heating temperature and the time within the above range.

  In this Embodiment, it is economically inferior that the softening point shall be 50 degreeC or more as a decomposed | disassembled urethane resin decomposition product, since grinding | pulverization at room temperature becomes difficult and processes, such as cooling, are needed. Further, even when cooled, the thermoplastic resin may be pulverized together because it approaches the embrittlement temperature of the thermoplastic resin, and separation becomes difficult.

(Second step: grinding step)
This step is a step of pulverizing the decomposition mixture obtained in the above step into a particle size suitable for fractionation by wind force or sieving. In the above process, only the urethane resin is chemically decomposed to lower the softening temperature, so that in this process, only the urethane resin is pulverized and the thermoplastic resin remains without being pulverized. In this step, an apparatus for pulverizing by impact such as a blender, a ball mill, a Henschel mixer or the like can be used. A cutter-type pulverizer capable of pulverizing a thermoplastic resin is not preferable because it makes separation difficult. In this step, the particle size of the urethane resin decomposition product contained in the decomposition mixture is preferably not more than the particle size of the thermoplastic resin, and is generally in the range of 0.01 to 1 mm. In order to make the particle size range below the above range, an excessive work man-hour is required, but the improvement of the effect commensurate with this is not seen, and it is not economical. Further, if the average particle size exceeds the above range, it is not preferable because it is not suitable for wind sorting with a thermoplastic resin having a close particle size.

(Third process: separation process)
This step is a step of separating the granular mixture obtained in the above step by means of wind force or sieving, but the method of separation is not particularly limited.

  Specifically, the wind sorting can employ a method in which the granular mixture is dropped from above the sorting device, an airflow is blown from the side, and different materials are sorted according to the weight difference. According to this method, the material having a large weight gathers near the dropping position of the granular mixture, while the material having a light weight gathers on the leeward side, and is collected by collecting it. In this method, the urethane decomposed product is treated in the first step, so that the foamed urethane resin is pulverized into a fine powder that easily flies with wind power. It becomes possible to separate.

  Alternatively, the thermoplastic resin is less likely to be pulverized in the pulverization step, and thus tends to become particles having a relatively large particle size. However, the decomposed urethane resin becomes particles having a small particle size because pulverization is relatively easy. . Therefore, it is possible to sort these mixtures by size separation (eg, a sieve).

  By the first to third steps, each resin can be separated and recovered from the mixture of polyurethane resin and thermoplastic resin with high accuracy, and each can be reused.

[Second Embodiment]
Hereinafter, an example of a resin material recovery apparatus according to the present embodiment will be described with reference to FIG. 1 showing an outline of the apparatus.
In FIG. 1, reference numeral 10 denotes a decomposition mixer, and a raw material charged from a raw material hopper 12 that supplies a mixture of urethane resin and thermoplastic resin as raw materials and a decomposition agent is driven by a rotary shaft 14 in an extruder 11. The urethane resin, the decomposing agent, and the thermoplastic resin are mixed by the screw 13 and heated as necessary to decompose the urethane resin.
The resin decomposition product extruded from the nozzle 15 of the extruder 10 is supplied to the pulverizing device 20 through the pipe 16. As the pulverizer 20, a known pulverizer such as a mixer blender, a stone mill, a hammer mill, or the like can be used.
The resin mixture pulverized by being placed in the pulverizer is then supplied to the separation device 30 through the pipe 21. For example, the separation device 30 is configured to blow a rapid flow into the separation chamber 34 from the blower 31 to the side surface of the hollow separation chamber 34 via the airflow pipe 32 and the airflow pipe branch pipe 33. Then, a plurality of collection containers 35 and 36 are arranged below the supply port 37 of the resin pulverized particles of the sorting device 30 and on the leeward side thereof. As a result, the particulate matter falling from the resin pulverized particle supply port 37 is caused to flow by the air flow from the blower 31 and is collected by the collection container arranged according to the position of the drop point due to the resistance difference of the air flow.

[Modification of Second Embodiment]
FIG. 2 shows an outline of an apparatus according to a modification of the second embodiment.
2, the same reference numerals are given to the same mechanism as that in FIG. 1, and detailed description thereof is omitted.
The apparatus of FIG. 2 is provided with a crushing apparatus 40 and a sorting apparatus 50 before the decomposition and mixing mechanism 10 of the apparatus of FIG. In this apparatus, for example, household electrical appliances that are wastes are crushed as they are by the crushing device 40, and the crushed particles are roughly classified by the sorting device 50 into inorganic materials such as metals and ceramics contained in the crushed particles, and resin materials. Thereafter, the crushed resin material and the decomposition agent are added and supplied to the decomposition mixer 10 of the second embodiment. According to this apparatus, the urethane resin material can be separated from the waste by consistent equipment.
In the apparatus of this modified example, as the crushing apparatus 40, an apparatus that supplies waste as a processing object between the twin rolls 41 and crushes between the twin rolls 41 can be used.
In this modification, it is preferable to employ a plurality of means such as separation using magnetism and separation using specific gravity as the separation mechanism 50.

In the above-described second embodiment and the modified example of the second embodiment, a specific mechanism is shown and illustrated as a recovery device. However, the present invention is not limited to these, and the same effect can be obtained. Of course, other mechanisms that can be expected can be used in place of or in addition to the above mechanism.
For example, in the above-described modification, an example of a separation mechanism using wind power is shown as the separation mechanism 50 in the previous stage. However, a separation mechanism using magnetism is arranged in front of the separation mechanism using wind power. The magnetic material can be removed prior to entering the mechanism 50.
Moreover, although the example of the crushing apparatus by a twin roll was shown as the crushing apparatus 40, it can replace with this and can employ | adopt the mechanism which crushes by impact like a hammer mill, and in addition to a twin roll mill mechanism, Such a mechanism can also be used in combination. Or it can replace with this twin roll and can also employ | adopt the shredder which passes a to-be-processed object between the rolls provided with the blade.
In addition, as the sorting device 30, a sorting device using a difference in particle diameter such as a vibrating sieve can be used, or it can be used together with wind sorting.

Furthermore, in the second embodiment and the modifications thereof, the separation mechanism is realized by a single device. However, by using a plurality of separation devices combined in multiple stages, a device with better separation accuracy can be obtained. Can be realized.

Hereinafter, a detailed study will be made based on examples.
Example 1
The waste refrigerator was crushed, and a plastic mixture (70% polyurethane, 15% ABS resin, 15% expanded polystyrene resin) from which metal was removed by magnetic sorting and large ABS resin was removed by wind sorting was prepared. ABS resin With respect to 10 parts by weight of this plastic mixture, 1 part by weight of diethanolamine was added, and the mixture was put into a single screw extruder heated to 280 ° C. and decomposed in a residence time of 5 minutes. When the obtained decomposition product was cooled, a mixture of brown urethane decomposition product, white ABS resin and polystyrene resin was obtained. The approximate particle size of the thermoplastic resin was 2 mm. It was 50 degreeC when the softening temperature of the urethane decomposition product was measured. This mixture was applied to a hammer-type pulverizer having a sieve having a mesh size of 0.5 mm and pulverized. The urethane decomposition product was finely pulverized and passed through the mesh, and the thermoplastic resin was not pulverized and did not pass through the mesh, so that it remained in the pulverizer and could be separated from the urethane resin decomposition product.

(Examples 2 to 6)
The urethane resin was decomposed in the same manner as in Example 1 except that the amounts of the urethane resin and diethanolamine were changed, and then pulverized and passed through a sieve.

(Comparative Example 1)
Fractionation was performed in the same manner as in Example 1 except that urethane resin / diethanolamine = 8/1. The softening point of the urethane decomposition product was 47 ° C. When put in a pulverizer, the urethane decomposition product was softened by heat generated during pulverization and could not be pulverized, and could not be separated from the thermoplastic resin.
Examples 1 to 6 and Comparative Example 1 are summarized in Table 1.

(Comparative Example 2)
Attempts were made to separate the plastic mixture before breaking down the urethane by wind sorting, and it was not possible to completely separate each plastic at any wind value.

(Comparative Example 3)
When the plastic mixture before decomposing urethane was put into the pulverizer used in Example 1 and pulverized, a part of the urethane resin could pass through the sieve, but most of the resin remained in the pulverizer. It was. For this reason, it was not possible to sort.

(Example 7)
Fractionation was performed in the same manner as in Example 2 except that the decomposition apparatus was a 200 ° C. flask. The time required for the decomposition was 80 minutes, and the softening temperature of the decomposition product was 58 ° C. Only the urethane decomposition product passed through the sieve of the pulverizer and could be separated from the thermoplastic resin. When the surface of the thermoplastic resin was confirmed, it was found that there were some urethane degradation products that could not be pulverized, and some remained on the surface of the thermoplastic resin.

(effect)
According to the present invention, the urethane resin and the thermoplastic resin can be separated, and the recycling of each can be promoted. Therefore, the industrial utility is very large.

Schematic of the collection device of this embodiment Schematic of another recovery device of the present embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Decomposition mixer 11 ... Oshida machine 12 ... Raw material hopper 13 ... Screw 14 ... Rotating shaft 15 ... Nozzle 16 ... Piping 20 ... Crushing device 30 ... Separation device 31 ... Blower 32 ... Airflow piping 33 ... Airflow piping branch 34 ... Separation chamber 35 ... Recovery container 36 ... Recovery container 40 ... Crushing device 41 ... Twin roll 50 ... Sorting device

Claims (5)

A first step of obtaining a decomposition mixture containing a urethane decomposition product having a softening point of 50 ° C. or more by reacting a decomposition agent with a resin mixture containing a urethane resin and a thermoplastic resin to lower the molecular weight of the urethane resin;
A second step of pulverizing the decomposition mixture containing the urethane decomposition product and the thermoplastic resin obtained in the first step;
A method for recovering a resin material, comprising a third step of separating the pulverized product obtained in the step into a urethane decomposed product and a thermoplastic resin. The method for recovering a resin material according to claim 1, wherein the decomposing agent is an amine compound . The method for recovering a resin material according to claim 2 , wherein the molecular weight of the urethane resin is reduced by kneading the mixture in a kneader .   A mechanism in which a decomposing agent is reacted with a resin mixture containing a urethane resin and a thermoplastic resin to lower the molecular weight of the urethane resin and decompose into a decomposition mixture containing a urethane decomposition product having a softening point of 50 ° C. or higher, and the decomposition mechanism obtained. An apparatus for recovering a resin material, comprising: a mechanism for pulverizing the decomposition mixture containing the urethane decomposition product; and a mechanism for separating the urethane decomposition product and the thermoplastic resin. The resin material recovery apparatus according to claim 4, wherein a mechanism for decomposing and decomposing the urethane resin is a kneader .

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