JP2001293723A - Method for manufacturing regenerated polyester resin pellets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide regenerated polyester resin pellets having sufficient moldability and adaptable also to the manufacture of a polyester long fiber. SOLUTION: In a method for manufacturing the regenerated polyester resin pellets, flaky polyester obtained by grinding PET bottle is used as a starting raw material to be melted in an extruder and the molten polyester is filtered by a filter to be pelletized. At this time, foreign matter in the molten polyester is filtered off by a filter having the same mesh size as a filter used in a molding process on and after pelletization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fiber, a film,
The present invention relates to a method for producing recycled polyester resin pellets that can be used for applications using recycled polyester resin such as nonwoven fabric.

[0002]

2. Description of the Related Art Recently, environmental issues relating to the disposal of synthetic resin products have been greatly addressed. This is a problem because synthetic resins generally remain without being decomposed by soil microorganisms even when buried in the ground, and even when incinerated, the combustion temperature is high, and there is a concern that toxic gas may be generated. . For this reason, it is being studied to reuse the synthetic resin product instead of discarding it. As a method of recycling, for example, there is a method of once melting a used synthetic resin product and reshaping it into another product form. In general, after the synthetic resin product is collected, it is formed through the steps of separation, crushing, washing, drying, and pelletizing.

[0003] At this time, a large amount of impurities such as contaminants and coating agents are mixed in, and the molding efficiency is deteriorated. In order to remove impurities in the above process, for example, a filter is installed in a pelletizing apparatus to remove the impurities.However, from the balance with production equipment, it is not sufficient for the molding process. The situation has not been removed. In particular, when put into the process of manufacturing polyester filament,
The operability such as an increase in the back pressure of the nozzle and the breakage of the yarn is deteriorated due to the influence of impurities, and the production cannot be performed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a recycled polyester resin pellet which maintains sufficient moldability and can produce polyester filament. is there.

[0005]

The gist of the production method according to the present invention is to filter foreign matter mixed in recycled polyester resin pellets with a filter having the same opening or smaller as a filter used in molding. Usually, when performing the molding process, the molten resin is filtered with a mesh filter, a sintered filter or the like for the purpose of removing impurities and improving the moldability. The aperture of the filter to be used varies depending on the product to be molded. However, if these filters are not used, poor moldability and poor passability of the molding process such as generation of defects will lead to defects of the product. In particular, when using recycled polyester resin, removal of impurities is an important point, and it is an indispensable technique for expanding use. The inventors of the present invention have conducted extensive studies on the thought that it is possible to contribute to environmental problems by expanding the use of recycled polyester resin only by the removal of impurities. As a result, the present invention has been achieved.

That is, a first aspect of the present invention is to use a flake-like polyester obtained by pulverizing a PET bottle as a starting material, melt it with an extruder, filter it through a filter, and pelletize it. A method for producing recycled polyester resin pellets, characterized by filtering using a filter having the same opening size or less as the filter used in the subsequent molding process,

The second is a method for producing recycled polyester resin pellets according to claim 1, wherein the opening size of the filter is 60 μm or less,

Third, the regenerated polyester resin pellet according to claim 1, wherein the filter has an opening size of 30 μm or less, and a booster for improving the filter passage efficiency is provided in the apparatus for pelletizing through the filter. It is a manufacturing method of.

The present invention is characterized in that, in producing pellets of a recycled polyester resin, the contaminants mixed therein are filtered through a filter having the same opening or smaller as a filter used in a molding process after pelletization. As described above, for example, in the field of fibers, a mesh filter of about 400 mesh or less for short fibers, and 60 μm for long fibers.
The use of a sintered filter of about m or less is exemplified.

[0010] In particular, in order to produce a resin to be used for the production of long fibers, the filter used has an aperture of 60 µm or less.
It is necessary to be preferably 40 μm or less, more preferably 20 μm or less. When spinning with a resin using a filter having a mesh size exceeding 60 μm, clogging of the filter in the nozzle pack increases, and the replacement cycle of the nozzle pack becomes extremely short. Further, if the filter of the nozzle pack is made coarse in order to prevent this, the replacement cycle will be prolonged, but this will lead to yarn breakage and an increase in defects in the spinning process. The effect of impurities differs depending on the thickness of the single filament of the long fiber, but in consideration of versatility, the thickness is preferably 40 μm or less, more preferably 20 μm or less. It is also effective to use a combination of filters having coarse openings.

Equipment for producing pellets from ordinary flakes includes a device for supplying flakes, a device for melting and extruding flakes, a device for filtering a melt, a device for molding a molten polymer such as a nozzle, and a device for cutting into pellets. It is composed of In addition, the device for filtering the melt is equipped with a filter for filtering the molten polymer, filters using the tip pressure of the extruder, backwashes the filter due to clogging of impurities, or replaces the filter continuously or batchwise. In general, a method of filtering by means of a filter is generally used, and it is actually used.

However, in this apparatus, when a filter having a fine opening as described above is used, not only is the filter clogged quickly, but it is difficult to pass through the filter at the tip pressure of the extruder due to pressure loss. It is also possible to use a combination of filters with coarse openings, but it is possible to produce pellets of recycled polyester resin using a device provided with a booster to increase the efficiency of filter passage in the device. preferable.

The booster is exemplified by a gear pump or the like, but is not limited to this, and any device can be used as long as it can apply a pressure that overcomes the pressure loss of a filter having a fine opening. Fig. 1 shows the outline of the device. FIG. 1 is a block diagram of an apparatus for generally forming regenerated flakes into pellets, and FIG. 2 is an example of the apparatus of the present invention.

[0014]

Next, an embodiment of the present invention will be described. The flakes made from the used PET bottles were pelletized with the apparatus shown in FIG. Flakes at 280 ° C
After passing through a first-stage filter (mesh size: 200 mesh), the pressure was increased by a gear pump, and then filtered by a second-stage filter. This was extruded from a nozzle, cooled with water, and then cut into pellets. Table 1 shows the openings of the used filters. Using this pellet, 84dt
Ex / 24 filament long fiber was produced. Table 1 shows the rise in the back pressure of the nozzle and the state of yarn production.

[0015]

[Table 1]

As is clear from Table 1, it is clear that the pellets produced by the production method of the present invention are excellent in operability and sufficiently contribute to the expansion of use of recycled pet resin.
As described above, the method for producing a recycled polyester resin according to the present invention has been specifically described. However, the present invention is not necessarily limited to the above examples, and may be appropriately modified within a range that can conform to the above-described purpose. All of them are included in the technical scope of the present invention.

[0017]

The method for producing a recycled polyester resin according to the present invention contributes to solving (or reducing) environmental problems by using the recycled polyester resin, and promotes recycling.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a conventional general pellet manufacturing facility.

FIG. 2 is a block diagram showing an example of a pellet production facility of the present invention.

[Explanation of symbols]

 1: Flake supply device 2: Extrusion device 3: Filtration device 4: Nozzle 5: Water cooling device 6: Cutting device 7: Pressurizing device

Claims (3)

[Claims] 1. A flake-like polyester obtained by pulverizing a PET bottle is used as a starting material, melted by an extruder, and filtered to form a pellet by filtering through a filter. A method for producing recycled polyester resin pellets, wherein the pellets are filtered using a filter having the same opening size or less as the filter. 2. The method for producing recycled polyester resin pellets according to claim 1, wherein the opening size of the filter is 60 μm or less. 3. An apparatus for reducing the opening size of a filter to 30 μm or less and pelletizing through a filter,
The method for producing recycled polyester resin pellets according to claim 1, further comprising a booster for improving filter passage efficiency.