JPH07214555A - Reusing method for polycarbonate molded waste - Google Patents

Abstract

PURPOSE:To manufacture recycled molded form such as recycled sheet, etc., having excellent physical properties such as impact resistance by removing detrimental low-molecular weight part for recycling by cutting a surface layer. CONSTITUTION:Polycarbonate recycled raw material is obtained by removing a surface layer of waste of polycarbonate used for a long period by cutting and then pulverizing it, and its recycled raw material is used as a molding 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 recycling waste such as a polycarbonate sheet which has been used for a long period of time.

[0002]

2. Description of the Related Art Polycarbonate sheets have impact resistance,
Due to its excellent heat resistance, it is widely used as a daylighting material, a sound insulation board for highways, etc.
If the sheet surface is scratched or discolored, it will be disposed of as industrial waste. Generally, incineration or landfilling is the most common method of disposing of such sheet waste, but in the case of incineration, a special incinerator is required. Needless to say, there is a great deal of difficulty such as the need to secure a cutting device and a landfill, and there is concern that it may cause environmental pollution. For this reason, there is a strong demand for the development of a technology for recycling polycarbonate sheet waste.

On the other hand, it is well known that a defective molding product generated by extrusion molding of a new polycarbonate material or scrap such as cutting scraps is crushed and reused as a molding material. Therefore, by using this well-known technique, it is possible to reuse a polycarbonate sheet that has been used for a long period of time, specifically, crush sheet waste and use it as a molding material to produce a recycled molded product such as a recycled sheet. Can be considered.

[0004]

However, a recycled sheet produced by recycling polycarbonate sheet waste based on the above-mentioned well-known technique is inferior in physical properties, particularly impact resistance, and can withstand actual use. Was not.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for reusing polycarbonate molding waste, which enables the production of recycled molded articles having excellent physical properties, particularly impact resistance. To aim.

<Analysis of Sheet Waste> By the way, the present inventor analyzed a polycarbonate sheet used outdoors for a long time and conducted various experiments using the sheet. As a result, it has been found that the polycarbonate sheet has a reduced molecular weight due to long-term use, and the reduced molecular weight causes the physical properties such as impact resistance of the regenerated molded article to deteriorate.

As a result of further detailed analysis, the long-term use of the polycarbonate sheet shows that the molecular weight is remarkably reduced in the surface layer portion of the sheet, but not so much in the inner layer portion. Found. Specifically, as shown in the graph of FIG. 1, a polycarbonate sheet used for about 10 years as a sound insulating plate for a highway was cut from the surface every 0.1 mm thickness to determine the molecular weight of each cut piece. When the relationship between the depth from the surface and the molecular weight was investigated by measuring by the viscosity method, the depth from the surface was 0 to 0.1 mm.
The molecular weight was 17,200 in the portion. Furthermore, in the portion where the depth from the surface is 0.1 mm to 0.2 mm, the molecular weight is 18700, and the depth is 0.2 mm.
The molecular weight is 19400 in the portion of 0.3 mm, the molecular weight is 19900 in the portion of 0.3 mm to 0.4 mm, and the depth is 0.4 mm to 0.5 m.
The molecular weight was 20,000 in the m portion. Further, in the portion where the depth exceeds 0.5 mm, even if the depth is increased, the molecular weight slightly increases and does not change so much.

[0008]

[Means for Solving the Problems] Based on the above analysis results and the like, the present inventor has conducted careful examination and as a result, when a long-term use polycarbonate sheet was used as a molding material, the decrease in the molecular weight was not observed so much. The inventors have found that a remolded article having excellent physical properties can be produced by using the inner layer portion of the sheet, and have completed the present invention.

That is, the method for recycling the polycarbonate molding waste of the present invention is to remove the surface layer portion of the polycarbonate molding waste by cutting and then pulverize it to obtain a polycarbonate recycled raw material, and use the recycled raw material as a molding material. The purpose is to use.

In the present invention, the cutting thickness of the surface layer of the polycarbonate molding waste is 0.3 mm to 0.5.
It is good to use mm.

Further, in the present invention, it is preferable to add a new polycarbonate material to the molding material in a predetermined ratio in addition to the recycled raw material.

The structure of the present invention will be described in detail below.

In the present invention, any polycarbonate molding waste can be used as long as it is a waste of a polycarbonate molded product, and specifically, for example, a polycarbonate sheet which has been used for a long time as a sound insulation plate of a highway, The sheet waste that can be collected in a large amount at one time can be preferably used.

In the present invention, the surface layer portion of the molding waste,
For example, in the case of a sheet, it is necessary to cut and remove the surface layer portions on the front surface side and the back surface side.

The cutting thickness at this time is 0.3 mm to 0.5
It is good to use mm. That is, the cutting thickness is 0.3 mm
If the amount is less than the above, as can be seen from the analysis result shown in FIG. 1, the low-molecular weight portion remains in the waste, so the molecular weight of the molding material formed by crushing it also becomes low, and the regenerated molding produced. The physical properties such as impact resistance may deteriorate in the product, which is not preferable. Further, cutting with a thickness exceeding 0.5 mm results in cutting and removal to a portion where the molecular weight is not so much reduced, that is, a portion useful for reuse, which is not preferable in practice.

When the cutting treatment is carried out, it is preferable to use a device excellent in cutting ability such as a wide cutting width, a high cutting speed and no noise, for example, a vertical milling machine. However, in the present invention, the cutting method is not particularly limited, and any cutting method may be used. For example, a cutting tool such as a router or a plane used for plastic processing or woodworking may be used. Although it is possible to perform cutting using these tools, since these tools generally have inferior cutting ability, the effects of the present invention can be enjoyed, but some defects may occur.

When the surface of the waste sheet is heavily soiled, it is preferable to wash the surface with a detergent or water jet before cutting the surface layer. By doing so, it is possible to prevent impurities from being mixed into the polycarbonate regenerating raw material described later, and to produce a good regenerated molded product.

The cut molding waste is cut into a size that can be processed by a crusher in the next step by using a circular saw, a guillotine or the like, like scrap generated during extrusion molding of a new raw material. It

Subsequently, the cut pieces are crushed by a crushing machine such as a rotary cutter mill, a roll crusher and a hammer crusher to a size usable as a molding material, specifically, a size of about 6 mm to 10 mm. To be done.

Then, a polycarbonate reclaimed raw material composed of this pulverized material is used as a molding material and extrusion-molded using a well-known extrusion molding machine to prepare a remolded article such as a reclaimed sheet having excellent physical properties such as impact resistance. can do.

In the extrusion molding process, in addition to the polycarbonate regenerating raw material, for example, a known polycarbonate nascent raw material produced by a known method from a bisphenol compound is blended at a predetermined ratio and used as a molding material. Well, in that case, it is possible to produce a remolded product having further excellent physical properties such as impact resistance.

[0022]

EXAMPLES Examples of the present invention, comparative examples and control examples for deriving the effects thereof will be described below.

<Embodiment 1> 10 as a sound insulation plate for expressways
The surface layer portion of the front surface side and the back surface side of the 5.0 mm-thick polycarbonate sheet waste used for a year was cut by a vertical milling machine to a thickness of 0.4 mm. Then, this cut sheet waste was pulverized to a size of 6 mm to 10 mm using a rotary cutter mill to obtain a polycarbonate recycled raw material.

Further, the recycled raw material and the new polycarbonate raw material are mixed at a weight ratio of 1: 1 to form a molding material, and the molding material is extruded using a known extruder to form a sheet having a thickness of 3 mm. A regenerated molded article of was produced.

Using the recycled sheet as a sample, the tensile strength according to the test method of JIS K 6735, the elongation according to the test method of JIS K 6735, and the J
The Izod impact strength according to the test method of IS K7110 was measured. The measurement results are shown in Table 1 below.

[0026]

[Table 1] <Example 2> The same polycarbonate recycled material as in Example 1 above was used as it was as a molding material and extruded,
A recycled sheet having a thickness of 3 mm was prepared in the same manner as above, and the same measurement was performed as shown in Table 1 above.

<Comparative Example 1> The same polycarbonate sheet waste as in Example 1 was crushed in the same manner as above to obtain a polycarbonate recycled raw material, and the recycled raw material was used as a molding material for extrusion molding to carry out the same procedure as above. A recycled sheet of was prepared and the same measurement was performed. The results are shown in Table 2 below.

[0028]

[Table 2] <Comparative Example 2> The surface layers on the front surface side and the back surface side of the same polycarbonate sheet waste as in Example 1 were cut by a vertical milling machine to a thickness of 0.2 mm.
Subsequently, the cut sheet was crushed to a size of 6 mm to 10 mm using a rotary cutter mill to obtain a polycarbonate recycled raw material.

Then, extrusion molding was carried out using the recycled raw material as a molding material to produce a recycled sheet similar to the above, and the same measurement was carried out as shown in Table 2 above.

<Comparative Example> Extrusion molding was carried out using only the new polycarbonate material as a molding material to prepare a sheet-shaped molded article similar to the above, and the same measurement was carried out. The measurement results are also shown in Table 2 above.

<Evaluation> As is apparent from Tables 1 and 2 above,
In the recycled sheets of Examples 1 and 2 related to the present invention, the elongation and Izod impact strength are high, the tensile strength is appropriate, and they are not easily embrittled, and the physical properties are sufficient to withstand actual use. It is understood that it has one. Moreover, these measured values are close to the physical properties of the molded product made of the new polycarbonate material shown in the control example, and it can be seen from this point that the physical properties are good.

On the other hand, the regenerated sheets of Comparative Examples 1 and 2 have low elongation and Izod impact strength, have excessively high tensile strength and are easily embrittled, and have poor physical properties. I understand.

[0033]

As described above, according to the method for recycling the polycarbonate molding waste of the present invention, the surface layer of the waste such as the polycarbonate sheet which has been used for a long time is preferably about 0.3 mm to 0.5 mm. After cutting and removing with a thickness of 1, the regenerated raw material is obtained by crushing, and the regenerated raw material is used as a molding material. Therefore, the above-mentioned cutting removes a low molecular weight portion harmful to reuse. Therefore, there is an effect that a recycled molded product such as a recycled sheet having excellent physical properties such as impact resistance can be produced.

Further, in the present invention, the above-mentioned molding material is
When a new polycarbonate material is blended in a predetermined ratio in addition to the recycled material, there is an advantage that a recycled molded product having further excellent physical properties can be produced.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the depth from the surface and the molecular weight of a polycarbonate sheet waste used for 10 years.

Claims (3)

[Claims] 1. A method for reusing a polycarbonate molding waste, wherein a polycarbonate reclaimed material is obtained by cutting and removing a surface layer portion of the polycarbonate molding waste and then pulverizing the polycarbonate reclaimed material to be used as a molding material. . 2. The method for recycling polycarbonate molding waste according to claim 1, wherein the cutting thickness of the surface layer of the polycarbonate molding waste is 0.3 mm to 0.5 mm. 3. The method for reusing polycarbonate molding waste according to claim 1, wherein a new polycarbonate material is added to the molding material in a predetermined ratio in addition to the recycled raw material.