JPH06304489A - Method for pulverizing plastic material - Google Patents

Abstract

PURPOSE:To provide a method for pulverizing plastic material wherein the kind of the applicable plastic material is not limited and the mean particle diameter of particles is regulated to the desirable size of the degree not larger than specified mum and also the plastic material is treated at a low cost. CONSTITUTION:A mixed raw material being in a state wherein respective plastic materials having different elasticity or impact resistance such as low density polyethylene, high density polyethylene, polypropylene, polystyrene, polyethylene, terephthalate and polyvinyl chloride are mixed is coarsely crushed in particle diameter of about 5 mm by a coarse crusher 2. Thereafter the coarse granular material obtained after coarse crushing is mechanically pulverized at ordinary temperature by a pulverizer using an internal classification method wherein shearing force and impact force become main stress controlling pulverization. Fine powder obtained after such pulverization is taken out through a bag filter 3 and a blower 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for finely crushing a plastic material for finely crushing the plastic material.

[0002]

2. Description of the Related Art Conventionally, thermal recycling, chemical recycling, etc. have been used as methods for recycling waste plastic materials.
Although there are methods such as recycling and material recycling, thermal recycling, in which waste plastic materials are recycled as heat for fuel for power generation boilers, etc., is considered to be the main recycling method in the future. However, looking at the current situation, about 66% of waste plastic materials were incinerated even in 1989, but about 25% of this incinerated material is used as a power generation energy source.

To incinerate a plastic material, it is important to make the plastic material into a fine powder or a slurry.
In other words, if the plastic material is compressed and reduced in volume as in the conventional case and incinerated in the form of lumps (coarse particles), the load fluctuation of the combustion furnace is large, unburned components are easily generated, and the calorific value is large. There is a problem such as damage to the wall material, and it is difficult to maintain a good combustion state. However, if the plastic material is made into fine powder or slurry, such a problem does not occur. In other words, the load fluctuation of the combustion furnace can be suppressed, the combustion speed can be increased (complete combustion), a good combustion state can be maintained without damaging the furnace wall material, and the burner structure for existing power generation boilers etc. The plastic material can be used as a fuel with a slight modification. In addition, since the handling is improved, it is easier to store and transport than the lump form (coarse grain), and the flexibility of the scale of the combustion equipment can be increased.

In such fine pulverization of plastic material for incineration of plastic material, the particle size is 1 mm.
It is appropriate to finely grind the following particles so that the cumulative weight of particles of 300 μm or less is 50% or more of the whole and the cumulative weight of particles of 400 μm or less is 80% or more of the whole (hereinafter, such The desired particle size is simply "average particle size 300μ
m or less "). By finely pulverizing to a particle size of this degree, it is possible to sufficiently enjoy the above-described advantages of making the plastic material into fine powder or slurry.

[0005]

However, in general, thermoplastics such as polyethylene (hereinafter referred to as "P
Plastic materials such as E), polypropylene (hereinafter "PP"), polystyrene (hereinafter "PS"), polyethylene terephthalate (hereinafter "PET"), polyvinyl chloride (hereinafter "PVC"). Has the following drawbacks. (1) It is highly elastic, hard to break, and crushes when compressed. (2) Generally has no heat resistance. (3) Even for resin materials with the same product name, the particle size distribution, particle shape, etc. will differ due to differences in manufacturers, additives used, etc. In particular, this is remarkable in PVC. (4) It is easily charged. (See "Powder and Industry, VOL.23, NO.5, p. 39-45 (Powder and Industry Co., Ltd.)") In the mechanical pulverization method using a pulverizer, shearing force and impact force are pulverized. A crusher with a main stress that governs is often used. Such problems arise. That is, (1) In general, in the mechanical grinding method,
Even if the same crusher is used, the crushing characteristics and crushing efficiency will be extremely different depending on the type of plastic material, and the particle size and particle size will vary. There are many things. In addition, there are also so-called “beard” projections that occur on the particles after fine pulverization.
Further, there are many cases such as PP in which fine pulverization is often difficult because it is melted by the heat generated when it is applied to a pulverizer. (2) Only PS etc. can be satisfactorily pulverized in terms of average particle size by mechanical pulverization.

Further, in response to the fact that the plastic material is rich in elasticity or impact resistance, according to the freeze pulverization method, the plastic material is cooled by liquefied nitrogen or the like to make it brittle so that it is easily broken and crushed. Although it can be applied to many kinds of plastic materials, it cannot necessarily be crushed to the above-mentioned desired average particle size and requires liquefied nitrogen, etc., resulting in high running costs and high value-added cosmetic materials. Also, it is difficult to apply it only to raw materials such as powder coatings.

Further, in the chemical crushing method in which a plastic material is chemically treated and crushed, ultrafine particles of several μm to several tens of μm can be crushed. Generally, however, crystalline plastic materials and non-crystalline plastic materials are used. The chemical treatment method is different for and, and the crushing method must be changed for both, and the process is also very complicated.As with the freeze crushing method, the running cost is high and the cosmetic material with high added value Also, it is difficult to apply it only to raw materials such as powder coatings.

In addition to the above problems, a plurality of types of plastic materials to be finely pulverized are mixed and provided, for example, in the case of pulverizing the waste plastic materials for recycling. It may be done.
In such a case, if the plastic materials can be crushed one after another by one method while being mixed without being sorted by type, the efficiency of the crushing work can be greatly improved and the processing cost can be reduced. .

The present invention solves these various problems and is not limited to the type of plastic material that can be applied. The average particle size of the particles can be set to a desirable size of about 300 μm or less, and the processing can be performed at low cost. An object of the present invention is to provide a method for finely pulverizing a plastic material that can be used.

[0010]

Means for Solving the Problems The gist of the present invention for solving the above problems is to provide a plurality of types having different elasticity or impact resistance by mechanical crushing in which shearing force and impact force are main stresses that control crushing. In the method of finely pulverizing a plastic material, the method further comprises the step of finely pulverizing a mixed raw material obtained by mixing the coarse-grained plastic material.

The gist of the method for finely pulverizing the plastic material is that one of the plurality of kinds of plastic material is a polystyrene material.

Further, in any one of the above, the mixed raw material is replaced with at least one kind of coarse-grained plastic material and the plastic material is mixed with a material having different elasticity or impact resistance to perform the fine pulverization. The method of finely pulverizing the plastic material is also included in the summary.

[0013]

[Function] By mechanically pulverizing shearing force and impact force as main stresses that control pulverization, finely pulverizing a mixed raw material in a state of mixing a plurality of coarse-grained plastic materials having different elasticity or impact resistance. It can be finely pulverized to an average particle size of about 300 μm or less. In addition, the generation of so-called “beard” or columnar particles can be suppressed. This is because when the above mechanical crushing is performed, plastic materials having different elasticity or impact resistance collide with each other in the crusher, so that plastic materials having the same elasticity or impact resistance collide with each other. This is probably because the crushing effect due to the collision of the materials is high.

The polystyrene material has properties such as being hard, low in elasticity and weak against impact, and when one of a plurality of kinds of plastic materials is a polystyrene material, the crushing effect is particularly high.

The above-mentioned fine pulverization is performed by using a mixed raw material in which one kind of coarse-grained plastic material and the plastic material are different in elasticity or impact resistance. Since the materials having different properties collide with each other, the crushing effect is high as in the case where the plastic materials having different elasticity or impact resistance collide with each other.

[0016]

EXAMPLES An example of the present invention will be described below.
FIG. 1 is a diagram for explaining the outline of the steps of the method for finely crushing a practic material according to this embodiment. With reference to the figure, the outline of the steps of this embodiment is as follows. First, a mixed raw material made of a plurality of types of plastic materials is crushed by a coarse crusher 2 into coarse particles.
In this coarse crushing process, it is usually sufficient to crush the plastic material to a particle size of about 5 mm. After that, the plurality of types of coarsely-grained plastic materials are finely crushed by the fine crusher 1.
The powder is finely pulverized by means of the bag filter 3 and the blower 4, and fine powder in a state in which plural kinds of plastic materials are mixed is taken out as a finely pulverized mixture 5.

The cooler 6 is installed as needed in order to cool the air introduced into the fine pulverizer 1 and keep the inside of the fine pulverizer 1 at room temperature. The normal temperature mentioned here means a temperature of about 40 ° C. or lower, preferably about 25 ° C. or lower (the same applies hereinafter). In this way, keeping the inside of the fine pulverizer 1 at room temperature generates heat in the fine pulverizer 1 in the process of performing fine pulverization, but in the plastic material, like the above-mentioned PP, etc., it is generated. This is because some of them may be melted by the heat applied, and it may be difficult to pulverize them.

Next, the structure of the fine pulverizer 1 and the fine pulverization process by the apparatus will be described. FIG. 2 is a cross-sectional view illustrating the schematic structure of an example of the fine pulverizer 1 used in the method for finely pulverizing the practic material of this embodiment. The fine crusher 1 is an impact compression crush type, which uses shearing force and impact force as the main stresses that govern crushing, and has been widely used in the past. The classification method is an inner partial classification method that does not use a screen. As described above, the air cooled by the cooler 6 is supplied to the inside of the fine pulverizer 1 in order to keep the inside of the fine pulverizer 1 at room temperature. The air flow created by the air and the air flow moves along with the air flow. The flow of the plastic material is indicated by the arrow in the figure.

First, a plurality of types of coarse-grained plastic materials coarsely pulverized by the coarse pulverizer 2 to have a grain size of about 5 mm are supplied to the pulverizing section 11 in the fine pulverizer 1 by the screw feeder 10. This coarse-grained plastic material is used for the grinding disk 12 rotating at a high speed and the liner 1 around it.
Between 3 and 3, it receives a stress mainly composed of a shearing force and an impact force and is crushed. The crushed plastic material is guided to the classification section 15 by the guide ring 14. This classification section 15
Then, the crushed plastic material undergoes a classification action due to the balance between the centrifugal force of the separator 16 that rotates at a high speed and the centripetal force of the air flow sucked into the classifying unit 15, and the fine powder passes through the separator 16 and outside the fine crusher 1. And is collected by the bag filter 3 and taken out as a finely pulverized mixture 5. The particle size of the fine powder taken out as a product is adjusted by adjusting the rotation speed of the separator 16. Separator 1
The coarse-grained plastic material separated in 6 returns to the crushing section 11 from the inside of the guide ring 16 and is crushed again.

Next, the results of comparative experiments carried out by the above apparatus and process will be described. In this experiment, the results of pulverizing the mixed raw material in which multiple types of plastic materials were mixed in the above process and the results of pulverizing the single raw material consisting of only one type of plastic material in the above process in place of the mixed raw material To compare.

The type of plastic material constituting the mixed raw material used in this experiment is low density polyethylene (hereinafter,
"LDPE"), high-density polyethylene (hereinafter,
"HDPE"), PS, PP, PET and PVC
There are 6 types. LDPE in these mixed raw materials
24wt%, HDPE 24wt%, PS 16wt%, PP 23wt%
%, PET 3% by weight, PVC 10% by weight. This ratio almost corresponds to the weight ratio of waste plastic materials discarded in Japan in recent years. That is, the mixed raw material used in this experiment is close to the average composition of the waste plastic material mixed with various plastic materials discarded in Japan. On the other hand, for single material, LDPE, HDPE, PS, PP, PET
And PVC were used individually. Recycled products are used for both mixed raw materials and single raw materials.

As the fine pulverizer 1, a Pulverizer ACM-10 manufactured by Hosokawa Micron Co. was used. The grinding disk 12 has a rotation speed of 6800 rpm and an electric power of
7.5 KW / 29.8 A (rated), the separator 16 had a rotation speed of 1000 rpm and an electric power of 3.1 KW / 3.2 A (rated).
The amount of air blown to the fine pulverizer 1 was 15 Nm ³ / min, the temperature of the air blown to the fine pulverizer 1 was about 18 ° C., and the temperature of the air at the outlet of the fine pulverizer 1 was about 31 ° C.

The results of the above experiment are shown in FIGS. FIG. 3 summarizes the results of observing the average particle size and particle shape of the plastic material fine particles obtained in this experiment for the mixed raw material and each single raw material. The average particle size was obtained from a particle size distribution curve by a sieving method using a JIS standard screen. In the case of using PVC as a single material, it was left blank because fine pulverization was insufficient or impossible. The particle size distribution curve for the mixed raw material is shown in FIG. 5 to 10 are enlarged photographs of finely pulverized material particles obtained from the mixed raw material and each single raw material in this experiment. 5 is a mixed raw material, FIG. 6 is a single raw material by LDPE, FIG. 7 is a single raw material by HDPE, FIG. 8 is a single raw material by PS, FIG. 9 is a single raw material by PP, and FIG.
Each of the finely pulverized particles of the single raw material by ET is shown. Since a single raw material made of PVC cannot be pulverized sufficiently or impossible, such a photograph as a substitute for a drawing is not shown. It should be noted that the enlargement magnification is 18.8 times in any of FIGS.

As is clear from the above results, in the case of a single raw material, there are many so-called "beard" particles. Fine pulverization was insufficient or impossible for a single raw material made of PVC.

On the other hand, in the mixed raw material, the average particle diameter of the single raw material was much larger than 500 μm.
Even though E, HDPE and PP accounted for 71 wt% of the total, the obtained fine particles achieved the ideal average particle diameter of 230 μm, and the cumulative weight of 300 μm or less was 60% of the total fine powder.
%, The cumulative weight of 400 μm or less reaches 80% or more of the total fine powder, and as shown in FIG. 5, no very large particles are found. Moreover, this is a result including PVC, which was insufficient or impossible to pulverize as a single raw material and occupies 10 wt% of the whole. Furthermore, there is almost no "beard" or columnar particles. These are because the plastic materials having different elasticity or impact resistance collide with each other in the fine crusher 1, so that the crushing effect of the plastic materials due to the collision is greater than that when the plastic materials having the same elasticity or impact resistance collide with each other. Is considered to be high.

The plastic material applied to the present invention is not limited to the plastic material used in the above embodiment, but may be applied to various plastic materials such as ABS resin and thermoplastic resin such as polyamide. is there.
As the physical properties of the finely pulverized plastic material, it is desirable that the Izod impact value is about 1 to 100 kgf · cm / cm and the glass transition temperature is about −140 to + 160 ° C.

Further, PS has characteristics that it is hard, has low elasticity and is weak against impact, and when one of a plurality of plastic materials is PS, the crushing effect is particularly high.

Further, even if at least one kind of plastic material as a mixed raw material is mixed and a material having different elasticity or impact resistance from the plastic material is mixed and used as a mixed raw material, the elasticity or impact resistance is different. Since the materials collide with each other, the crushing effect of the plastic material is high as in the above embodiment. Therefore, for example, when finely pulverizing waste plastic material for thermal recycling, other fuel such as coal or thermosetting resin material such as phenol resin is mixed with this, and after fine pulverization, coal or phenol is mixed. It is also possible to use it as a fuel as it is in a state where resins and the like remain mixed.

In addition, PP, which has been conventionally impossible or difficult to be finely pulverized by a mechanical pulverization method at room temperature, is pulverized by the above-mentioned method, and then the mixture finely pulverized mixture 5 is subjected to an appropriate method such as specific gravity selection. The mechanical pulverization method of the PP alone at room temperature is also possible.

[0030]

As described above, according to the method for finely pulverizing a plastic material of the present invention described above, the average particle size of the plastic material can be determined by a single method without limiting the type of the plastic material that can be applied. It can be pulverized to a diameter of 300 μm or less. Moreover, by such fine pulverization, the generation of so-called "beard" or columnar particles can be suppressed.

Further, since the method of the present invention can be carried out by mechanical crushing, in which the shearing force and the impact force, which have been widely used conventionally, are the main stresses that govern the crushing, the existing equipment can be used as it is. In addition, since mechanical crushing can be performed at room temperature regardless of the freeze crushing method or chemical crushing method, various plastic materials can be finely crushed with a single method and equipment without the need for liquefied nitrogen and complicated processes. Therefore, when finely pulverizing the average particle diameter of the plastic material to about 300 μm or less, the equipment cost and the operating cost can be significantly reduced.

Further, even when a plurality of kinds of finely crushed plastic materials are mixed and provided, for example, when the waste plastic materials are crushed for recycling, the plastic materials are not sorted by type. In the mixed state, the crushing treatments can be performed one after another by a single method, so that the efficiency of the crushing treatment can be greatly improved, and in this respect as well, the equipment cost and the operating cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an outline of steps of a method for finely pulverizing a practic material according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the structure of a fine pulverizer used in the method for finely pulverizing a practic material according to an embodiment of the present invention.

FIG. 3 is a view showing an average particle diameter and a particle shape of the fine particles of the plastic material obtained in this example, in each of the mixed raw material and each single raw material in the method for finely pulverizing the practic material according to one embodiment of the present invention. It is a figure which shows the result.

FIG. 4 is a diagram showing a particle size distribution curve for a mixed raw material in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 5 is a photograph as a substitute for a drawing in which a finely pulverized mixture obtained from a mixed raw material is enlarged and photographed in the method for finely pulverizing a plastic material according to an example of the present invention.

FIG. 6 is a photograph as a substitute for a drawing, in which a fine powder obtained from a single raw material by LDPE is enlarged and photographed as a comparative example in the method for finely pulverizing a plastic material according to an example of the present invention.

FIG. 7 is a drawing-substituting photograph taken by enlarging a fine powder obtained from a single raw material by HDPE as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 8 is a drawing-substituting photograph taken by enlarging a fine powder obtained from a single raw material by PS as a comparative example in the method for finely pulverizing a plastic material according to an example of the present invention.

FIG. 9 is a photograph as a substitute for a drawing, in which a fine powder obtained from a single raw material of PP is magnified and taken as a comparative example in the method for finely pulverizing a plastic material according to an example of the present invention.

FIG. 10 is a photograph as a substitute for a drawing, in which a fine powder obtained from a single raw material by PET is magnified and taken as a comparative example in the method for finely pulverizing a plastic material according to an example of the present invention.

[Explanation of symbols]

 1 Fine crusher 2 Coarse crusher 3 Bag filter 4 Blower 5 Fine crushed mixture 6 Cooler 10 Screw feeder 11 Grinding part 12 Grinding disk 13 Liner 14 Guide ring 15 Classification part 16 Separator

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[Procedure amendment]

[Submission date] October 13, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram illustrating an outline of steps of a method for finely pulverizing a practic material according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the structure of a fine pulverizer used in the method for finely pulverizing a practic material according to an embodiment of the present invention.

FIG. 3 is a view showing an average particle diameter and a particle shape of the fine particles of the plastic material obtained in this example, in each of the mixed raw material and each single raw material in the method for finely pulverizing the practic material according to one embodiment of the present invention. It is a figure which shows the result.

FIG. 4 is a diagram showing a particle size distribution curve for a mixed raw material in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 5 is a drawing-substituting photograph taken by enlarging the particle structure of a finely pulverized mixture obtained from a mixed raw material in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 6 is a drawing-substituting photograph obtained by enlarging a particle structure of fine powder obtained from a single raw material by LDPE as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 7 is a photograph as a substitute for a drawing in which a particle structure of fine powder obtained from a single raw material by HDPE is enlarged and taken as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention.

8 is a drawing-substituting photograph obtained by enlarging the particle structure of fine powder obtained from a single raw material by PS as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention. FIG.

FIG. 9 is a drawing-substituting photograph obtained by enlarging the particle structure of fine powder obtained from a single raw material of PP as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention.

FIG. 10 is a photograph as a substitute for a drawing in which a particle structure of fine powder obtained from a single raw material by PET is enlarged and taken as a comparative example in the method for finely pulverizing a practic material according to an example of the present invention.

[Explanation of Codes] 1 Fine crusher 2 Coarse crusher 3 Bag filter 4 Blower 5 Fine crushed mixture 6 Cooler 10 Screw feeder 11 Grinding section 12 Grinding disk 13 Liner 14 Guide ring 15 Classification section 16 Separator

Front page continuation (72) Kenji Sato, 1st Hachiman Kaigan Dori, Ichihara-shi, Chiba Mitsui Engineering & Shipbuilding Co., Ltd., Chiba Works (72) Mitsuo Kaji 4-1-1, Toranomon, Minato-ku, Tokyo Corporation Hojin Plastic Processing Within the promotion association

Claims (3)

[Claims] 1. A mixed raw material in which a plurality of types of coarse-grained plastic materials having different elasticity or impact resistance are finely pulverized by mechanical pulverization in which shearing force and impact force are main stresses that control pulverization. A method for finely pulverizing a plastic material, which comprises steps. 2. The method for finely pulverizing a plastic material according to claim 1, wherein one of the plurality of plastic materials is a polystyrene material. 3. The fine pulverization is performed with a mixed raw material in which at least one kind of coarse granular plastic material and a coarse granular material having different elasticity or impact resistance are mixed in place of the mixed raw material. The method for finely pulverizing a plastic material according to claim 1 or 2.