JP2002167469A - Recycling system for waste polyester and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a system capable of reproducing original polyester products any number of times from wastes containing polyester. SOLUTION: A depolymerization reaction by ethylene glycol and/or a transesterification by methanol are carried out by using a waste polyester as a material, a polyester material which has a quality as equivalent as that of a market product is produced by using a process in which dimethyl terephthalate and ethylene glycol are separated and refined, and the polyester product is produced from these materials and is resupplied to the market.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and a method for recycling active ingredients from polyester waste, and more particularly, to a system for recycling a polyester which can be carried out semi-permanently by avoiding quality deterioration due to the recycling. Regarding the method.

[0002]

2. Description of the Related Art The consumption of polyethylene terephthalate bottles (hereinafter sometimes abbreviated as PET bottles) is increasing year by year, and the treatment of used PET bottles is a major problem. In contrast, recently used P
Separate collection and recycling of ET bottles are required by law, and the government and the private sector are working together to collect and recycle used PET bottles. However, of the PET bottles that have been separated and recovered at present, only high quality bottles with a low content of coloring matter and impurities can be recommercialized into fiber products and solid PET products.
Most bottles containing coloring and impurities have been incinerated or landfilled.

[0003] In addition, polyester products such as futons and uniforms, cushion materials, flooring materials, films, and resin products generate a large amount of waste as the amount of use increases. The treatment of these polyester wastes has become a major social problem at present, and various proposals have been made on recycling methods. JP-A-11-302
Japanese Patent No. 443 proposes a method of recycling dimethyl terephthalate, which is a main raw material for the production of polyester products, from used PET bottles as a method of recycling into raw materials. Only high-quality PET bottles that can sufficiently perform separation, crushing, washing, etc., and polyester processed into polyester products such as futons and uniforms, cushioning materials, flooring materials, films, resin products, etc. are recycled. Can not. For this reason, polyester used for such applications must be incinerated or discarded, and there remains a problem as a technology for forming a recycling-oriented society.

[0004]

The current recovery and recycling system has the following problems. First, since the problem of contamination is not completely solved, the quality of the product greatly varies. In addition, since the quality is reduced by recycling, the types of applicable products are limited, resulting in overproduction compared to the market. On the other hand, most polyester products other than PET bottles such as fibers and films are thermally recycled as general and industrial wastes, and a treatment method that does not promote environmental destruction is desired. According to the present invention, a recycling system capable of producing a polyester polymer of the same quality as that of a commercially available product by chemically recycling the polyester waste and then repolymerizing the same, and using the same to produce a polyester product of the same quality as many times as possible. Can be constructed.

[0005]

Means for Solving the Problems To solve the above-mentioned problems, the present inventors have developed polyester waste containing PET bottle waste and the like, polyester waste containing foreign matter, futon and large polyester waste such as cushioning material, Polyester wastes such as uniforms containing dyes and flame retardants, and polyester wastes containing chemicals such as lubricants (wastes as referred to in the present invention may be valuable or non-valent) As a result of intensive studies on how to obtain a product of the same quality as the original polyester product, using the starting material (good) as a starting material, the following system was found.

[0006] That is, an object of the present invention is to recover a polyester-based product and / or a polyester-based waste generated in the process of producing the product, which are commercially available from the market, By carrying out a depolymerization reaction with ethylene glycol and a transesterification reaction with methanol as raw materials, a dimethyl terephthalate and ethylene glycol are separated and purified. This can be achieved by a polyester recycling system characterized by producing polyester products from raw materials and circulating and supplying them to the market. According to the recycling system, polyester waste that is currently incinerated or landfilled Can also produce high purity polyester products , It is possible to effectively utilize the resources.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the polyester recycling system of the present invention, a pretreatment step will be described first. It is preferable that the polyester resin waste is pulverized to 2 to 30 mm square in the pretreatment step in terms of the reactivity in the reaction step or the transportability after the pretreatment step, more preferably 5 to 20 mm. . The reactivity is improved by this operation. This effect is particularly effective in a portion where the thickness of the portion that has been crystallized and whitened for increasing the strength and dimensional stability of the PET bottle is thick. In addition, as an embodiment of the pulverization, it is preferable to use a two-stage pulverizer in order to improve the pulverization processing capacity.
That is, the waste is roughly pulverized to 30 to 150 mm by a primary pulverizer, and then pulverized to 2 to 30 mm by a secondary pulverizer.

When the size of the pulverized material is specified directly at 2 to 30 mm in the primary pulverizer, the load applied to the pulverizer becomes excessive and inefficient. Also the first
It is effective to reduce the load on the cutter of the secondary pulverizer by providing a magnetic separator for removing the metal or the like which is a packing material of the polyester resin after the next pulverization. In the pulverized material,
In many cases, different plastics are mixed with polyester such as polyethylene, polypropylene, polystyrene, and polyvinyl chloride, which are cap or label materials contained as impurities in the polyester resin. In the present invention, reaction conditions are selected so as not to decompose in the subsequent reaction step and reduce the purity of the recovered product with respect to the contamination of the different plastics. Because there is a possibility of adverse effects on handling such as sticking, causing filter clogging,
It is important to remove the different plastics in the pretreatment step and to minimize the incorporation into the reaction step in order to promote the reaction smoothly. However, various steps for completely removing the different plastics as in the case of material recycling are not required, and only a minimum necessary step is required.

In order to remove a thin film (polyethylene, polypropylene, polyvinyl chloride, etc.) used for labels, which is different from polyester, from the pulverized material,
First, it is preferable to remove the label by wind sorting.
At this time, if the air volume is too large, the polyester resin which is an effective component is removed together with the air volume, so it is necessary to appropriately adjust the air volume. By this wind separation, labels mainly composed of polypropylene, polystyrene and polyvinyl chloride can be almost completely removed.

[0010] Next, it is preferable that the pulverized material is decanted to remove caps that cannot be removed by wind separation, and that different plastics, such as polypropylene and polyethylene, having a lower specific gravity than water are removed by centrifugation. Since the decanter also serves as a facility for washing impurities (such as soy sauce and soft drinks) derived from food and the like remaining in the polyester resin, there is no problem even if the contents remain in the resin. Wash water separated by centrifugation is recycled to the decanter again, and a part is purged and subjected to wastewater treatment.

The recovered flakes discharged from the decanter are transported to the reactor in the reaction step by air transport.
The size after grinding in the previous grinding step is 30-150m
When it is specified to be relatively large as m, problems such as deterioration of transport efficiency in this pneumatic transport step and blockage of a rotary valve occur, so that it is effective to pulverize to about 2 to 30 mm as in the present invention. is there. Although the recovered flakes before the pneumatic transportation have moisture remaining, they are dried during the pneumatic transportation and eventually the water content may be reduced to 0.1% or less based on the weight of the recovered flakes. it can. Most of the components other than polyester can be removed in the above pretreatment step.

Next, the pretreatment of fiber and film waste will be described. Since materials different from polyester, for example, nylon, polyethylene, polypropylene, cotton, etc. cannot be effective ingredients, it is preferable to remove waste containing a large amount of these at the stage of acceptance. That is, when the waste is analyzed by a discriminating device such as a near-infrared spectrometer and shows an absorption pattern different from that of the polyester, it is effective to exclude the waste at that stage without transporting it to the next step. The waste that has passed the inspection by near-infrared analysis is desirably granulated and solidified in terms of handling properties in the reaction step after the pretreatment step or pneumatic transport properties after the pretreatment step. However, it is extremely difficult to directly feed yarn waste, film waste, and the like having a continuous structure into a granulator, and it is necessary to first pulverize the waste into an appropriate size. The size of the pulverized product is preferably 2 to 50 mm. If the crushed diameter is large, a problem that solidification becomes insufficient in the next granulation step occurs. In addition, as an embodiment of the pulverization, it is preferable to use a two-stage pulverizer in order to improve the pulverization processing capacity. That is, the polyester waste is roughly pulverized to 30 to 150 mm by a primary pulverizer, and then pulverized to 2 to 50 mm by a secondary pulverizer. When the size of the pulverized product is directly defined in the primary pulverizer to 2 to 50 mm, the load applied to the pulverizer becomes excessive,
Warping becomes inefficient.

Next, the pulverized material is put into a granulator, and the pulverized material is solidified into a cylindrical solid. The size of the diameter is preferably 2 to 20 mm, more preferably 4 to 6 mm.
The length is preferably 2 to 60 mm. The granulation method is a method in which the pulverized material is pushed into a hole having a defined size, and a part of the surface is melted by frictional heat of the polyester surface generated at that time and solidified as a binder, but the diameter is large. As a result, the surface of the solidified product is not sufficiently solidified due to the influence of a small frictional heat. Insufficient solidification in this way causes the solids to collapse in the subsequent transportation process due to collision with the pipe, resulting in a structure that is easy to form a bridge in the storage tank at the destination, and extremely difficult to discharge from the storage tank. .
In the granulation method, the operation is performed at a temperature not lower than the glass transition point of the polyester and not higher than the melting point. That is, as a granulation method, there is a method in which the waste is heated to a temperature equal to or higher than the melting point of the polyester and completely melted, and then cooled and solidified. However, in the granulation method, impurities such as nylon are heated due to high temperature. Decomposes and deteriorates the quality of recovered products. Therefore, it is preferable to carry out a granulation method in which only a part of the surface of the waste is melt-pressed at an operating temperature of not less than the glass transition point of the polyester to be granulated and not more than 195 ° C. The granulation method can improve the handleability while suppressing the decomposition of impurities and the decrease in the reaction rate. In this method, even if resin waste is mixed as polyester waste, there is no problem.

Next, using polyester waste as a raw material,
A process for producing dimethyl terephthalate and ethylene glycol, which are main raw materials of polyester, will be described. The polyester waste appropriately pulverized / washed / separated in the pretreatment step is first subjected to a depolymerization reaction in EG in the presence of a known depolymerization catalyst. Here, examples of the polyester include polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. The depolymerization reaction of polyester with EG is carried out at a temperature of 110 to 19
Preferably it is 5 ° C. That is, when the depolymerization reaction temperature is 1
When the temperature is lower than 10 ° C., the depolymerization time becomes very long. On the other hand, when the temperature exceeds 195 ° C., when polyester waste containing nylon is used as a raw material, nylon is thermally decomposed and DMT is decomposed.
And EG are mixed with nitrogen compounds and deteriorate the quality of polyester products produced by using them.

The reaction temperature of the transesterification with methanol (hereinafter sometimes abbreviated as MeOH) is in the range of 50 to 150 ° C., and the reaction pressure is
The pressure is preferably in the range of 0.0 to 0.59 MPa (gauge pressure). In this range, the transesterification reaction is sufficiently performed.

Here, any of known depolymerization catalysts and transesterification catalysts as depolymerization catalysts and transesterification catalysts can be used. However, carbonates, bicarbonates, and carbonates of alkali metals and alkaline earth metals can be used. It is preferable to use at least one compound selected from the group consisting of acid salts from the viewpoint of high catalytic ability. Furthermore, it is particularly preferable to use sodium carbonate in all cases. In the mixture obtained by this transesterification reaction, DMT,
There are MeOH, EG, and by-products from EG depolymerization and transesterification. These are purified by a method such as separation, recrystallization, washing, or distillation by a known method such as centrifugation.

Next, the DMT obtained by the above operation
Is used as a raw material for polyester production in combination with EG by a known high-purity polymer production facility. At this time, the EG used by the above operation can be reused.

By these operations, a polyester polymer having a high purity equal to or higher than that of virgin can be obtained, and various polyester products can be produced in the same manner as virgin raw materials by a known technique.

The method for producing a high-purity polymer is a known method, and the production of a polyalkylene terephthalate resin composition will be described below for reference. The raw material containing DMT and EG obtained in the above production facility is subjected to a transesterification reaction in the presence of a transesterification catalyst to form bis (β-hydroxyethyl) terephthalate and / or an oligomer thereof, and thereafter, The polyalkylene terephthalate resin composition is obtained by performing melt polycondensation under high temperature and reduced pressure in the presence of a polycondensation catalyst and a stabilizer.

As the transesterification catalyst, alkaline earth metal salts such as magnesium and calcium, and metal compounds such as titanium, zinc and manganese are preferably used. Known polycondensation catalysts include germanium compounds, antimony compounds, titanium compounds, cobalt compounds, and tin compounds.

Examples of the stabilizer include phosphoric esters such as trimethyl phosphate, triethyl phosphate and triphenyl phosphate, phosphites such as triphenyl phosphite and trisdodecyl phosphite, methyl acid phosphate, dibutyl phosphate, and the like. Phosphorus compounds such as monobutyl phosphate acidic phosphate, phosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid are preferred.

The supply of the transesterification catalyst can be carried out at the initial stage of the transesterification reaction in addition to the preparation of the raw materials. The supply of the stabilizer can be performed before the initial stage of the polycondensation reaction, but is preferably added at the end of the transesterification reaction. Further, the polycondensation catalyst can be supplied by the beginning of the polycondensation reaction step. The reaction temperature during the transesterification reaction is usually 200 to 260 ° C,
The reaction pressure is from normal pressure to 0.3 MPa. The reaction temperature during the polycondensation is usually from 250 to 300 ° C, and the reaction pressure is usually from 60 to 0.1 kPa. Such transesterification reaction and polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. The polymer thus obtained has an intrinsic viscosity of usually 0.4 to 0.90 dl / g,
It is made into chips by a conventional method. The average particle size of the polymer chip is usually 2.0 to 5.5 mm, preferably 2.2 to 4.0 mm.
The range is 0 mm. Next, the polymer obtained by melt polycondensation as described above may be subjected to solid-phase polymerization. The polymer chip to be subjected to the solid-phase polymerization is preliminarily heated to a temperature lower than the temperature at which the solid-phase polymerization is performed to perform pre-crystallization, and then subjected to the solid-phase polymerization. In the pre-crystallization step, the amorphous polymer chips are always crystallized in one or two stages under a fluidized state so that fusion by chip crystallization heat does not occur. The next solid phase polymerization step comprises at least one stage, usually at a polymerization temperature below the fusion temperature of the polymer, at 0.05
It is carried out under a vacuum of ５5 kPa or a normal pressure の 0.1 MPa under a flow of an inert gas such as nitrogen, argon or carbon dioxide. The solid-state polymerization time may be shorter as the temperature is higher, but is usually 1 to 50 hours, preferably 5 to 30 hours, and more preferably 10 to 25 hours.

The above-mentioned high-purity dimethyl terephthalate is sent to a known terephthalic acid production facility by hydrolysis or the like, and EG obtained by transesterification of the above crude polyester monomer is purified together with purified EG as a raw material for polyester production. Can also be used. By adding this operation, the existing equipment for producing a polyester polymer from terephthalic acid can be used. The method for producing a high-purity polymer in this case is also a known method, but will be described below with reference.

The raw material containing terephthalic acid and ethylene glycol obtained by the above hydrolysis is subjected to an esterification reaction to form bis (β-hydroxyethyl) terephthalate and / or an oligomer thereof, and thereafter, a polycondensation catalyst and a stabilizer Is subjected to melt polycondensation under high temperature and reduced pressure to obtain a polymer. The esterification catalyst does not need to be particularly used because terephthalic acid becomes an autocatalyst in the esterification reaction. As the polycondensation catalyst, generally, a germanium compound, an antimony compound, a titanium compound, a cobalt compound, a tin compound and the like are known, but the polycondensation catalyst used in the present invention satisfies color tone, transparency, and hygiene. From the point of view, it is limited to germanium dioxide, and the addition amount is preferably 20 to 150 ppm (based on the acid component) of germanium element, more preferably 30 to 100 ppm, and further preferably 30 to 80 ppm.

Further, as a stabilizer to be added at the time of polymerization,
Phosphates such as trimethyl phosphate, triethyl phosphate and triphenyl phosphate, phosphites such as triphenyl phosphite and trisdodecyl phosphite, methyl acid phosphate, dibutyl phosphate, monobutyl phosphate acidic phosphate and phosphoric acid , Phosphorous acid, hypophosphorous acid, and polyphosphoric acid are preferred. The use ratio of the above catalyst is usually 5 to 5% by weight of the metal in the catalyst in all the polymerization raw materials.
1000 ppm, preferably in the range of 10 to 500 ppm, the proportion of the stabilizer used in the total polymerization raw materials, as a weight of phosphorus atoms in the stabilizer, usually 10 to 1000 ppm,
Preferably, it is in the range of 20 to 500 ppm.

The supply of the catalyst and the stabilizer can be performed at any stage of the esterification reaction or the transesterification reaction in addition to the preparation of the raw material slurry. Furthermore, it can be supplied at the beginning of the polycondensation reaction step. The reaction temperature during the esterification reaction or transesterification reaction is usually from 240 to 28.
0 ° C., and the reaction pressure is from normal pressure to 0.3 Mpa. The reaction temperature during the polycondensation is usually from 250 to 300 ° C, and the reaction pressure is usually from 60 to 0.1 kPa. Such an esterification or transesterification reaction and polycondensation reaction
It may be performed in one stage or may be performed in a plurality of stages. The polymer obtained in this way has an intrinsic viscosity of usually 0.45
０．７0.70 dl / g, which is formed into chips by a conventional method. The average particle size of the polymer chip is usually 2.0 to 5.5.
mm, preferably in the range of 2.2 to 4.0 mm.
Next, the polymer obtained by melt polycondensation as described above is usually subjected to solid-state polymerization. The polymer chip to be subjected to the solid-phase polymerization is preliminarily heated to a temperature lower than the temperature at which the solid-phase polymerization is performed to perform pre-crystallization, and then subjected to the solid-phase polymerization.
In the pre-crystallization step, the amorphous polymer chip is usually placed in a single-stage or in a fluid state at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. so as to prevent fusion due to chip crystallization heat generation. Treat in two steps for at least 15 minutes to crystallize.

The next solid phase polymerization step comprises at least one step, usually at 190 to 230 ° C., preferably at 195 to 22 ° C.
The polymerization is performed at a polymerization temperature of 5 ° C. under a vacuum of 0.05 to 5 kPa or under a normal pressure to 0.1 MPa under a flow of an inert gas such as nitrogen, argon, or carbon dioxide. The solid-state polymerization time may be shorter as the temperature is higher.
Hours, preferably 5 to 30 hours, more preferably 10 hours
~ 25 hours. The intrinsic viscosity of the polymer obtained by solid-state polymerization is usually 0.70 or more, and ~ 0.90 dl / g.
Range.

In the present invention, the content of diethylene glycol constituting the polyethylene terephthalate resin obtained by the above method is 0.7 to 2.0 wt% based on all diol units constituting the polyethylene terephthalate.
And preferably 1.0 to 1.5 wt%. If the amount is too small, the transparency of the bottle body after molding is deteriorated. If the amount is too large, the heat resistance is reduced and the crystallization promoting effect is reduced. As a method of adjusting the diethylene glycol content within the above range, in addition to using diethylene glycol as a polymerization raw material, diethylene glycol is partially produced as a by-product from ethylene glycol used as a main raw material. Can be adjusted. In addition, oligomer components contained in the polymer that causes mold contamination during bottle molding,
It is desirable to reduce the acetaldehyde component contained in the polymer, which affects the taste and smell of the bottle filling, as much as possible. The oligomer content is 0.5 wt% or less, particularly preferably 0.4 wt% or less. The acetaldehyde content is at most 5 ppm, particularly preferably at most 2 ppm. Since the reduction of oligomers and acetaldehyde is carried out in the above solid phase polymerization,
The target level is reached by adjusting the IV of the polymer after the melt polymerization, the solid phase polymerization time, and the temperature time.

The concentration of the terminal carboxyl group is 15-25.
It is particularly preferred to be in the range of eq / ton. If the concentration of the terminal carboxyl group is less than the above range, it may take a long time to increase the intrinsic viscosity due to poor solid-state polymerizability, while if it exceeds the above range, solid-phase polymerization When used, the effect of reducing oligomers such as CT may be small.

The above-mentioned polyester polymer is converted into a polyester film in a film-forming facility to form various polyester film products, or a polyester yarn or cotton in a thread-forming facility, textile clothing, carpet, interior materials for automobiles, futon,
Products such as flooring can also be used. Also, by subjecting the above polymer to the necessary treatment in a solid state polymerization facility,
It can also be used as a raw material for PET bottles and engineering plastics.

According to the recycling system of the present invention, the original polyester product group can be produced again from most of the polyester-containing waste, so that an almost complete “circulation-type recycling system” can be realized. Can be. At present, it is possible to easily recycle PET bottles and other polyester products containing fiber waste, including polyester bottles, into polyester products, and landfill them as general and industrial waste, and dispose of them by incineration and other environmental pollution-type disposal. Eliminates the need. For this reason, it is an effective recycling system for solving the waste disposal problem and achieving resource and energy saving.

The transesterification equipment, crude DMT purification equipment, hydrolysis equipment, monomer production equipment, polymer production equipment, EG / MeOH purification equipment, etc. used in the present invention are equipment already established as individual equipment. The feature of the present invention is to improve the pretreatment equipment and depolymerization equipment to general methods, and to construct a recycling system for used PET bottles, polyester waste such as clothing and films by combining with the above existing technologies. And return it to the original product group.

[0033]

EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to examples, but the present invention is not limited by these examples. The characteristics in the examples were measured by the following methods.

1) Intrinsic viscosity (hereinafter sometimes abbreviated as IV): A fixed amount of a sample cut from a chip and a molded body is weighed, and 0.012 g / ml is added to o-chlorophenol.
, And measured at 25 ° C.

2) Haze: 50 mm × 5 from bottle body
For a sample cut out to a size of 0 mm, Nippon Denshoku Industries Color and color differencen
It was measured with a ce meter (MODEL1001DP).

3) Method of identifying inorganic compound as identification compound: The metal component of the labeled compound in the resin composition is a fluorescent X
Line analyzer (Rigaku Denki Kogyo Co., Ltd., System32)
70) was used for qualitative and quantitative determinations.

4) Acetaldehyde (hereinafter sometimes abbreviated as AA) content: The AA content is determined by subjecting a sample to freeze crushing, charging the sample in a vial, keeping the sample at 150 ° C. for 60 minutes, and performing headspace gas chromatography manufactured by Hitachi. Was measured.

5) Diethylene glycol (hereinafter referred to as DEG)
Content: sample: decomposed with hydrazine, measured by gas chromatography

6) Col-b: A fixed volume of a sample is quantified and measured using a color machine CM-7500 type color machine.

[Example 1] PET bottle bale separated and collected by municipalities (bale size: 900 mm)
After unpacking a 120 kg bale of × 1000 mm × 550 mm), put it into the primary crusher, set the screen diameter of the crusher to 75 mm, perform primary crushing, and then transfer the crushed material to the secondary crusher. It was charged and the screen diameter of the pulverizer was set to 10 mm to perform secondary pulverization.

Thereafter, the pulverized product is applied to a wind separator to remove the label attached to the bottle mainly composed of polyethylene, polystyrene and polypropylene, and then centrifuged by a decanter to wash and remove the contents of the bottle with water. Remove polypropylene, caps mainly composed of polyethylene and labels that were not removed by wind separation,
Collected flakes. 100 kg of the recovered flakes was transported to the reaction step by air transport.

In the reaction step, the flakes were previously heated at 185 ° C.
The mixture was charged into a mixture of 400 kg of ethylene glycol and 3 kg of sodium carbonate, which had been heated to room temperature, and reacted at normal pressure for 4 hours. At this time, a polyester such as polystyrene and a different plastic which could not be removed in the pretreatment step floating on the EG liquid surface were removed by solid-liquid separation. After completion of the reaction, 300 kg of EG was distilled off at 140 to 150 ° C. and a pressure of 13.3 kPa. Next, 3 kg of sodium carbonate and 200 ml of methanol were added to 200 kg of the residue from which EG was distilled off.
kg was added thereto and reacted at normal pressure at 75 to 80 ° C. for 1 hour.

After completion of the reaction, the reaction solution was cooled to 40 ° C.
By centrifugation, solid-liquid separation was performed into a cake mainly composed of crude DMT and a filtrate mainly composed of methanol and crude EG. Then, the crude DMT was subjected to a pressure of 6.7 kPa and a bottom temperature of 180 to 2.
00 ° C., crude EG pressure 13.3 kPa, tower bottom temperature 140
Purified by distillation at ~ 150 ° C and finally DM
T and ethylene glycol were each obtained at a yield of about 85%. The recovered DMT was inferior to those of the commercially available DMT in terms of appearance, acid value, melting colorimetry, and sulfated ash.

A slurry comprising 40 kg of terephthalic acid (hereinafter sometimes abbreviated as “raw material recycled TA”) obtained by further hydrolyzing the DMT and 22 kg of ethylene glycol was supplied to a polycondensation tank, and the slurry was subjected to normal pressure. 275
The esterification reaction is carried out at 4 ° C. for 4 hours, water produced as a by-product flows out of the system, the reaction is carried out to an esterification reaction rate of 97%, an oligomer having a polymerization degree of 5 to 10 is prepared, and then ethylene Glycol solution (phosphorus concentration 5.5%) 0.01
7 kg and 0.38 kg of an ethylene glycol solution of germanium dioxide (concentration of germanium dioxide 1%) are added, and the pressure is reduced to 2,000 Pa for 1 hour under a reduced pressure of 2000 Pa.
The polycondensation was performed at 277 ° C. for 2 hours under the reduced pressure of a. The produced polymer was drawn out in a strand form from a drawing port provided directly connected to a cooling water tank at the bottom of the polycondensation tank, cooled with water, and then cut into chips to obtain polymer chips.

Subsequently, the obtained polymer chips were crystallized by a stirring and fluidizing type crystallizer, and then the mixture was cooled to 140 under nitrogen flow.
After drying at 3 ° C. for 3 hours, the mixture was transferred to a packed column type solid phase polymerization tower, and subjected to solid phase polymerization at 215 ° C. for 22 hours under a nitrogen flow to produce a chip-like polyethylene terephthalate resin composition. The obtained polyethylene terephthalate resin composition had an intrinsic viscosity of 0.75, DEG of 1.3 wt%, and AA =
1.5 ppm, Col-b = -1.0. After drying this chip at 160 ° C. for 5 hours in a drier, the cylinder temperature was 275 ° C. and the screw rotation number was 160 rpm by an injection molding machine (“M-100DM” manufactured by Meiki Seisakusho).
Primary pressure time 3.0 seconds, mold temperature 10 ° C, cycle 30 seconds, outer diameter about 28mm, inner diameter about 19mm, length 136m
m, and a cylindrical preform weighing about 56 g was injection molded. The intrinsic viscosity of the obtained preform was 0.69, the acetaldehyde content was 12 ppm, and the moldability and appearance were good. Subsequently, the surface temperature of the preform is about 11
Preheat to 0 ° C with infrared heater, blow pressure 5-40k
Stretch-blow molding was performed using a blow molding machine set to g / cm ² and a mold temperature of 150 ° C. to form a bottle having a body thickness of 330 μm and an internal volume of about 1.5 liters. The haze of the obtained bottle was 0.8%, and the moldability and appearance were good.

Example 2 An absorption spectrum of 100 kg of a mixed waste of polyester fiber waste and polyester film waste containing no dye generated from the polyester production process was measured by a near infrared spectrometer. did. The whole amount of the waste is put into a primary crusher, primary crushing is performed by setting the screen diameter of the crusher to 75 mm, and then the crushed material is put into a secondary crusher and the screen diameter of the crusher is set. Was set to 20 mm to perform secondary pulverization. Thereafter, the pulverized product was put into a granulator operated under the conditions of a diameter of 4 mm, a length of 45 mm, and an internal temperature of the granulator of 170 ° C., solidified, and then transported to the reaction step by air transport. The solidified product transported to the reaction step had a bulk density of 0.40 g / cm ³ .

In the reaction step, 100 kg of the solidified product was heated to 185 ° C. in advance using ethylene glycol 400.
kg and 3 kg of sodium carbonate, and reacted at normal pressure for 4 hours.

After completion of the reaction, the product was heated at 140-150 ° C.
300 kg of EG was distilled off under the condition of a pressure of 13.3 kPa. Next, 3 kg of sodium carbonate and 200 kg of methanol were added to 200 kg of the residue after distilling off EG,
The reaction was performed at 75 to 80 ° C for 1 hour.

After completion of the reaction, the reaction solution was cooled to 40 ° C.
By centrifugation, solid-liquid separation was performed into a cake mainly composed of crude DMT and a filtrate mainly composed of methanol and crude EG. Then, the crude DMT was subjected to a pressure of 6.7 kPa and a bottom temperature of 180 to 2.
00 ° C., crude EG pressure 13.3 kPa, tower bottom temperature 140
Each was purified by distillation under the condition of ~ 150 ° C, and finally DMT and ethylene glycol were respectively obtained in a yield of 85%.
I got it. The recovered DMT is comparable to the commercial product in terms of appearance, acid value, melting color, and sulfated ash, and the recovered ethylene glycol is comparable to the commercial product in terms of diethylene glycol concentration, water content, and melting color. Was.

50 kg of the DMT and ethylene glycol
32 kg of tetra-t as a transesterification catalyst
-Transesterification is carried out using butoxytitanium while distilling off by-product methanol out of the system. Further, germanium dioxide was added as a polymerization catalyst, and transesterification was performed while heating to 250 ° C., and at the stage when methanol was almost completely distilled off, orthophosphoric acid was added as a stabilizer to conduct transesterification. finished.

Next, the reaction product was subjected to a polycondensation reaction under a high temperature and a high vacuum to obtain a polymer having an intrinsic viscosity of 0.60. Subsequently, solid-phase solid-phase polymerization was performed to obtain an intrinsic viscosity of 0.83 and Col-
A polyalkylene terephthalate resin composition was obtained in which b = 2, DEG = 1.8 wt%, and AA = 2 ppm.

After the obtained polyalkylene terephthalate resin composition was dried in a dryer at 160 ° C. for 5 hours,
First, an injection molding machine (“M-100D” manufactured by Meiki Seisakusho)
M ”), cylinder temperature 275 ° C., screw rotation speed 160 rpm, primary pressure time 3.0 seconds, mold temperature 10
℃, cycle 30 seconds, outer diameter about 28mm, inner diameter about 19m
m, a length of 136 mm and a weight of about 56 g were injection molded into a cylindrical preform. The intrinsic viscosity of the obtained preform was 0.77, the appearance was good, and the injection moldability was also good. Subsequently, the preform is preheated to a surface temperature of about 110 ° C. with an infrared heater, and a blow pressure of 5 to 40 kg / c.
m ² , stretch blow molding with a blow molding machine set at a mold temperature of 150 ° C. to form a bottle with a body average thickness of 330 μm and an internal volume of about 1.5 liters.
The stretchability was good at 0.9%.

Second, the film thickness was set to 0.
A sheet of 5 mm was obtained.
C. and was thermoformed into a tray by compressed air. The haze of the tray was 1.0%, and the moldability was good.

Reference Example 1 The same procedure as in Example 1 was carried out except that terephthalic acid was virgin terephthalic acid (without discriminating compound) manufactured by Mitsui Chemicals, Inc. Intrinsic viscosity 0.75, C
ol-b = -1.5, DEG = 1.3 wt%, AA =
1.3 ppm of a polyethylene terephthalate resin composition was obtained.

A preform was injection-molded in the same manner as in Example 1. The intrinsic viscosity of the obtained preform was 0.69, the acetaldehyde content was 12 ppm, and the moldability and appearance were good. Furthermore, the haze of the blow-molded bottle as in Example 1 was 1.0%, and the moldability and appearance were good.

Reference Example 2 The procedure of Example 2 was repeated except that the DMT was Virgin DMT (without an identification compound) manufactured by Teijin. Intrinsic viscosity 0.82, Col-b = 2, DEG
= 1.8 wt%, AA = 2 ppm to obtain a polyalkylene terephthalate resin composition.

A preform obtained by molding the same in the same manner as in Example 1 had an intrinsic viscosity of 0.76, good appearance, and good injection moldability. Furthermore, the haze of the bottle blow-molded in the same manner as in Example 2 was 0.9%, and the stretchability was good.

Further, the tray formed by thermoforming in the same manner as in Example 2 had a haze of 1.1%, and the moldability was good.

[Comparative Example 1] Using polyester waste obtained by cutting a blend of polyester and nylon of 10 to 20 mm as fiber waste, 65 kg of ethylene glycol was added to 100 kg of fiber waste, and the temperature was 205 ° C and the internal pressure was 0.25.
The procedure was performed in the same manner as in Example 1 except that the depolymerization reaction was performed under the conditions of MPa. The quality of the obtained dimethyl terephthalate is
Inspection items such as appearance, acid value, colorimetric color, and sulfated ash are all significantly worse than those of commercial products.Recovered dimethyl terephthalate and ethylene glycol contaminate nitrogen compounds and can be used as raw materials for polyester products. I could not do it.

[0060]

As described above, the recycling system for polyester waste according to the present invention is capable of converting high-purity dimethyl terephthalate and ethylene from general polyester waste (eg, PET bottles, uniforms, futons, films, etc.) containing polyester. This is a recycling type recycling system that produces glycols and uses them as raw materials to produce a polyester product group again. Therefore, it is a recycling type recycling system capable of recycling used polyester products into polyester products of the same quality as the original. This eliminates the need for landfill and incineration as general and industrial waste, thereby achieving resource and energy savings.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 63/26 C07C 63/26 AG // C08L 67:02 C08L 67:02 (72) Inventor Kazuhiro Sato 77F, Kitayoshida-cho, Matsuyama-shi, Ehime F-term (reference) in Matsuyama Office of Teijin Limited 4F301 AA25 CA23 CA33 CA34 CA41 CA68 CA72 CA73 4H006 AA02 AA05 AC26 AC46

Claims (3)

[Claims] 1. A polyester-based product commercially available on the market and / or a polyester-based waste generated in a process for producing the product is recovered, and the polyester-based waste is dissolved in ethylene glycol. Carry out a polymerization reaction and a transesterification reaction with methanol,
Separation of dimethyl terephthalate and ethylene glycol,
A polyester recycling system that uses a refining process to produce polyester materials of the same quality as those on the market, and then produces and circulates and supplies polyester products from these materials to the market. 2. The dimethyl terephthalate generated by the method according to claim 1 is hydrolyzed to obtain terephthalic acid having a quality equivalent to that of a commercially available product. A polyester recycling system that circulates and supplies. 3. A polyester-based product commercially available on the market and / or a polyester-based waste generated in a process for producing the product is recovered, and the polyester-based waste is dissolved in ethylene glycol. A polymerization reaction is carried out, and a polyester polymer of the same quality as that of a commercially available polyester polymer is produced using a process of separating and purifying a polyester monomer and / or oligomer without carrying out a transesterification reaction with methanol. A polyester recycling system characterized by manufacturing and circulating and supplying polyester products to markets.