KR101269949B1 - Fire retardancy recycled polyester using waste polyester and method thereof - Google Patents

Abstract

The present invention is a method for producing flame-retardant regenerated polyester by depolymerization of waste polyester flakes, the primary depolymerization to produce bis-2-hydroxyethyl terephthalate (BHET) by mixing the waste polyester flakes and ethylene glycol (EG) Process; Bis-2-hydroxyethyl terephthalate (BHET) produced in the first depolymerization process by mixing all or part of the waste polyester flakes, ethylene glycol (EG) bis-2-hydroxyethyl terephthalate (BHET) A second depolymerization process for generating a; In the reaction tank separate from the depolymerization process, the bis-2-hydroxyethyl terephthalate (BHET) is mixed in a polycondensation process of polycondensation with regenerated polyester by mixing a phosphorus flame retardant, wherein the depolymerization process is the second after the first depolymerization process 2 The present invention relates to a method for producing a flame retardant regenerated polyester using waste polyester which is repeated only in the second depolymerization process using a part of bis-2-hydroxyethyl terephthalate (BHET) produced in the second depolymerization process.

Description

Flame retardant recycled polyester using waste polyester and its manufacturing method {FIRE RETARDANCY RECYCLED POLYESTER USING WASTE POLYESTER AND METHOD THEREOF}

In the present invention, waste polyester is separated from bis-2-hydroxyethyl terephthalate (BHET) using ethylene glycol, and flame retardant regenerated polyester is prepared from the separated bis-2-hydroxyethyl terephthalate (BHET). It is about a method.

As income increases and living standards rise, the amount of waste generated is on the rise, and they cause serious environmental pollution. Especially, waste synthetic resins account for about 15% of household waste, but many are foamed or blow molded. It takes up much more volume, and when incinerated, various harmful gases are generated, which causes smog, and it does not decompose even when landfilled.

As part of environmentally-friendly policies, the use of degradable resins such as photodegradable resins and biodegradable resins is gradually increasing. However, photodegradable resins do not show the degrading effect when they are buried in the ground, and biodegradable resins are 5 to 10 times more expensive than ordinary synthetic resins, which makes them difficult to be used in general. This was not good and there was a limit to using it industrially.

Therefore, in terms of environmental protection and recycling of resources, there is increasing interest in recycling waste synthetic resins rather than using degradable resins. In the case of advanced foreign countries, research on the recovery and recycling of useful resources from waste has already been carried out in various fields under long-term plans. In Korea, public awareness of environmental pollution has begun to emerge, and an economic recovery and recycling plan has been established, and related research is progressing.

Among general synthetic resins, polyester is the most widely used resin in textiles, films, food containers, etc., and the recycling of wastes such as waste polyesters generated during the process and waste polyesters such as beverage bottles discarded after use is a big concern. have.

Solidified polyesters are thermally unstable and it is almost impossible to reuse them after melting at temperatures above their melting point, so wastes must be recovered at lower temperatures. In the process of recovering the waste polyester, terephthalic acid (TPA), dimethyl terephthalate (DMT) and ethylene glycol (ethlyene glycol: EG), which are used as raw materials through depolymerization of waste polyester using a catalyst or the like. And a process of preparing bis-2-hydroxyethyl terephthalate (BHET), which is an intermediate product.

Among these processes, the process of recovering terephthalic acid, dimethyl terephthalate and ethylene glycol is a complicated process and takes a long time to recover terephthalic acid, dimethyl terephthalate and ethylene glycol by depolymerizing waste polyester, and the recovered terephthalic acid, dimethyl tere The process of producing regenerated polyester using phthalate and ethylene glycol has a disadvantage in that the procedure is complicated and takes a long time compared to the process of producing regenerated polyester with bis-2-hydroxyethyl terephthalate as an intermediate product. Therefore, a process for producing regenerated polyester recovering the intermediate bis-2-hydroxyethyl terephthalate has been developed, but regenerated polyester prepared from the recovered bis-2-hydroxyethyl terephthalate is recovered terephthalic acid and dimethyl. There was a problem that the physical properties or color is lower than the regenerated polyester made of terephthalate and ethylene glycol.

In addition, a general depolymerization process is performed by mixing and melting waste polyester and ethylene glycol to perform depolymerization, but the melting process of the waste polyester and ethylene glycol takes more than half of the entire process time for producing recycled polyester. Due to the melting time of, the production volume was lower than that of the general polyester manufacturing process, which prevented the recycling of waste polyester.

However, the biggest problem of the melting time that requires a long time is that if the depolymerization process and the polycondensation process are carried out in separate reactors, the reaction time of the depolymerization process and the polycondensation process is performed in a continuous circulation process at the production site. There is a problem that the process management is difficult because it does not have a long time. During the depolymerization process, the waiting time of the reaction tank during the polycondensation process becomes long, and the chemicals remaining in the reaction tank are solidified or carbonized and present as impurities in the polycondensation process. There was a problem of inhibiting the physical properties of the recycled polyester produced.

In addition, in recent years, as the demand for safety increases, the demand for flame retardancy also increases in polyester resins.

Examples of the method of imparting flame retardancy to synthetic fibers include a method of adding a flame retardant in a spinning step of fiberizing, and a method of copolymerizing with a monomer including a component having flame retardancy in a step of preparing a polymer for fiber (mainly a polymerization step). . Synthetic fibers generally impart flame retardancy in the spinning step.

In general, in order to impart flame retardancy of polyester, flame retardancy may be imparted from halogen and non-halogen compounds, and as the regulations of halogen compounds become more severe, the desire for environmentally friendly phosphorus-based flame retardants is increasing.

The method of imparting flame retardancy to a polyester by using a phosphorus-based flame retardant is a method of preparing a polyester master bezel resin containing a high concentration of flame retardant, and adding the same to a spinning process of the polyester resin at a predetermined ratio. This method can vary the content of the flame retardant, but the flame retardant should not be decomposed at the spinning temperature, the viscosity of the master batch resin containing a high concentration of flame retardant is reduced in viscosity, the flame retardant is not uniformly produced, fiber spinning Pack pressure may act as a factor that can rise in the city and has a problem of inferior flame retardancy.

The present invention has been invented to solve the above problems, to recover the good bis-2-hydroxyethyl terephthalate from the waste polyester by depolymerization by using the waste polyester to be discarded by ethylene glycol, It is an object of the present invention to provide a flame retardant regenerated polyester using waste polyester, in which a part of the recovered bis-2-hydroxyethyl terephthalate is used for depolymerization, which dramatically shortens the overall depolymerization process time, and a method for producing the same.

It is also an object of the present invention to provide a flame retardant recycled polyester using waste polyester having excellent flame retardancy due to a uniform distribution of a flame retardant by adding a phosphorus flame retardant to a polycondensation process and copolymerizing a flame retardant.

It is also an object of the present invention to provide a flame retardant recycled polyester having no difference in physical properties from a polyester produced by a general production method and a method for producing the same.

delete

The present invention is a method for producing a flame retardant recycled polyester by depolymerizing the waste polyester flakes, the waste polyester flakes and ethylene glycol (EG) in a molar ratio of 1.0: 0.1 ~ 2.0 and using nitrogen (N ₂ ) 1.5 After pressurizing at ~ 2.5㎏ / ㎠ and stirring for 10 ~ 50rpm at 210 ~ 240 ℃ 3-4 hours, the molten mixture was pressurized to 2.0 ~ 2.5㎏ / ㎠ using nitrogen (N ₂ ) gas and 245 A first depolymerization step of depolymerizing for 1.0 to 3.0 hours while stirring at ˜260 ° C. for 30 to 70 rpm to produce bis-2-hydroxyethyl terephthalate (BHET); All or part of the bis-2-hydroxyethyl terephthalate (BHET) produced in the first depolymerization process is mixed with waste polyester flakes and ethylene glycol (EG), wherein the waste polyester flakes and the ethylene glycol (EG ) And the bis-2-hydroxyethyl terephthalate in a molar ratio of 1.0: 0.1 to 2.0: 0.5 to 2.0, pressurized to 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas and 10 at 210 to 240 ° C. After 30-50 minutes of melting by stirring at -50 rpm, the molten mixture was pressurized to 2.0-2.5 kg / cm 2 using nitrogen (N ₂ ) gas and stirred at 30-70 rpm at 245-260 ° C. for 1.0-3.0 hours. A second depolymerization step of depolymerization to produce bis-2-hydroxyethyl terephthalate (BHET); A filtering step of removing foreign matter through a filter when the bis-2-hydroxyethyl terephthalate produced by the first depolymerization process or the second depolymerization process is transferred to a polycondensation reaction tank; And a polycondensation step of polycondensing the regenerated polyester by mixing a phosphorus flame retardant with the bis-2-hydroxyethyl terephthalate (BHET) in a separate reaction tank from the first depolymerization process or the second depolymerization process. The method for producing a flame retardant regenerated polyester using waste polyester, characterized in that the second depolymerization process is performed using only a part of bis-2-hydroxyethyl terephthalate (BHET) produced in the second depolymerization process. to provide.
In addition, the polycondensation process is a waste poly, characterized in that the bis-2-hydroxyethyl terephthalate is polymerized for 60 to 240 minutes while stirring at 30 to 90 rpm at 245 ~ 290 ℃ in a vacuum state to produce a recycled polyester Provided is a method for preparing a flame retardant recycled polyester using an ester.

delete

delete

The present invention also provides a flame retardant regenerated polyester production method using waste polyester, characterized in that H ₃ PO ₄ and Sb ₂ O ₃ are used as the polycondensation reaction catalyst in the polycondensation process.

In addition, on the basis of the bis-2-hydroxyethyl terephthalate, H ₃ PO ₄ is 100 ~ 200ppm, Sb ₂ O ₃ 300 ~ 600ppm characterized in that the flame-retardant recycled polyester production method using waste polyester To provide.

In addition, in the polycondensation process, flame retardant regenerated polyester using waste polyester, which is polycondensed by adding 0.01 to 3% by weight of TiO ₂ or SiO ₂ as a quencher as compared to bis-2-hydroxyethyl terephthalate. It provides a manufacturing method.

In addition, the phosphorus-based flame retardant provides a method for producing a flame retardant recycled polyester using waste polyester, characterized in that the phosphorus content is added 1000 ~ 8000ppm based on bis-2-hydroxyethyl terephthalate.

The present invention also provides a flame retardant recycled polyester production method using waste polyester, characterized in that the phosphorus content of the phosphorus flame retardant is 9 to 20% by weight.

In addition, the flame-retardant recycled polyester production using waste polyester, characterized in that the filtering step of removing foreign matter through the filter is carried out when the bis-2-hydroxyethyl terephthalate polycondensation reaction tank produced by the depolymerization process is carried out Provide a method.

The present invention also provides a flame retardant recycled polyester using waste polyester, which is produced by the above production method.

In addition, the flame-retardant regenerated polyester has a physical property of intrinsic viscosity (IV) 0.65 ~ 0.70 dl / g, acid value (-COOH) 5 ~ 45 eq / ton, melting point (Tm) 220 ~ 250 ℃, limit oxygen index (LOI) 28 or more Provided is a flame retardant regenerated polyester using waste polyester characterized in that

In addition, the flame retardant regenerated polyester provides a flame retardant regenerated polyester using the waste polyester, characterized in that the color L 40 is 40 ~ 70, b * 2 ~ 8.

In addition, the flame retardant regenerated polyester provides a flame retardant regenerated polyester using waste polyester, characterized in that the moisture content is 1wt% or less.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The terms "about "," substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

Chemical recycling methods of polyester include hydrolysis method which reduces water to monomer or oligomer phase using water, and glycols such as ethylene glycol (EG) or propylene glycol (PG). Glycolysis, methanolysis using methanol, and the like.

Glycol glycolysis can be carried out in a batch or continuous process, is less expensive than methanolysis or hydrolysis, and can be applied to more applications than remelt injection.

Therefore, the present invention recovers bis-2-hydroxyethyl terephthalate (BHET) by depolymerizing waste polyester by glycolysis using ethylene glycol, followed by polycondensation. It is about how to get it.

Synthetic resins are generally combusted by heating, pyrolysis, combustion and propagation processes. Heating is a process in which the temperature rises until the synthetic resin decomposes. The factors that affect the rate of temperature rise include specific heat, thermal conductivity, and phase transition (melting, sublimation, evaporation, etc.). Pyrolysis is the process by which heat is decomposed in the thermally unstable part of the fiber polymer. If heat is continuously supplied, the resin decomposes into solid and liquid phases, producing flammable and non-combustible gases. The relative amount of flammable and non-combustible gases depends on the nature of the resin, the added agent, and the airflow around it. Combustion is an exothermic reaction in which flammable fuel produced by pyrolysis combines with oxygen in the air to generate heat. Fibers are thermally decomposed by externally applied heat to produce flammable fuels, some of which combine with oxygen in the air to burn in flames to generate heat to the outside. Part of the heat generated by the exothermic reaction is used to continuously decompose the resin, and the rest is dispersed and lost to the surroundings. The propagation of a fire depends on the amount of heat generated during combustion and the amount of endotherm needed to raise the temperature. If the endothermic amount is greater than the calorific value, the fiber turns off itself (autogenous), and if the endothermic amount is less than the calorific value, the fire is propagated.

Therefore, in order to impart flame retardancy to the synthetic resin, a method of forming a film during combustion may be used to block combustion of oxygen and air in the combustible gas so that combustion does not occur or a calorific value is reduced.

The principle of imparting flame retardancy to fibers is to change the pyrolysis path of the fiber to reduce the amount of flammable gas and to increase the amount of residual carbide to impart flame retardancy (i.e., to impart flame retardancy by reducing combustibles and increasing carbides). ) And flame retardancy by changing the combustion method (that is, pyrolysis process is constant regardless of the addition of flame retardant, but flame retardation works by changing the combustion method of flame).

Phosphorus-based flame retardants produce phosphoric acid and polyphosphoric acid by pyrolysis. Phosphoric acid and polyphosphoric acid produced at this time have a flame retardant effect due to the formation of nonvolatile phosphoric acid by esterification and dehydration reaction, and include phosphate ester aromatics and phosphate ester oligomers.

The process for producing regenerated polyester of the present invention is a depolymerization process of depolymerizing waste polyester flakes with bis-2-hydroxyethyl terephthalate (BHET) and bis-2-hydroxyethyl terephthalate (BHET) as regenerated polyester. The polycondensation is carried out in a polycondensation process, and the depolymerization process and the polycondensation process are carried out in separate reactors, and bis-2-hydroxyethyl terephthalate (BHET) produced through the depolymerization process is transferred to the reaction tank of the polycondensation process. The present invention relates to a method for obtaining a flame retardant polyester by carrying out a polycondensation step, and adding a phosphorus flame retardant during the polycondensation step.

The depolymerization process of the present invention is a primary depolymerization step of producing bis-2-hydroxyethyl terephthalate (BHET) by mixing waste polyester flakes and ethylene glycol (EG), and bis- produced in the first depolymerization step Depolymerization after depolymerization using all or part of 2-hydroxyethyl terephthalate (BHET) to depolymerization, followed by depolymerization of bis-2-hydroxyethyl terephthalate (BHET) by primary depolymerization The process is carried out only with the second depolymerization process.

The waste polyester flakes are pulverized into a flake shape of 1 to 20 mm by removing a metal component, a synthetic resin of different components, and the like from the collected waste polyester, and using a grinder to melt the waste polyester flakes. It will be desirable to grind finely into 1-5 mm for ease.

The first and second depolymerization processes are performed to melt the waste polyester flakes to react with ethylene glycol and to mix the melted polyester flakes with ethylene glycol and to mix and melt the waste polyester flakes with ethylene glycol. As shown in Scheme 1, it can be divided into a depolymerization process for producing bis-2-hydroxyethyl terephthalate.

[Reaction Scheme 1]

~ COOCH ₂ CH ₂ OOC ~ + HOCH ₂ CH ₂ OH ↔ 2 (~ COOCH ₂ CH ₂ OH)

In the first depolymerization process, the waste polyester flakes and ethylene glycol (EG) are mixed at a molar ratio of 1.0: 0.1 to 2.0, pressurized to 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas, and then at 210 to 240 ° C. After stirring for 3 to 4 hours by stirring at 10 to 50 rpm, the molten mixture was pressurized to 2.0 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas and then stirred at 30 to 70 rpm at 245 to 260 ° C. for 1.0 to 3.0 hours. During the depolymerization process.

The mixing ratio of the waste polyester flakes and ethylene glycol (EG) in the first depolymerization process is too long when the ethylene glycol is mixed less than 0.1 mole with respect to 1 mole of the waste polyester flakes when the mixing time is longer than 2.0 moles Since the shortening effect of the reaction time is not great, it may be preferable to mix the waste polyester flakes with ethylene glycol (EG) in a molar ratio of 1.0: 0.1 to 2.0.

The mixed waste polyester flakes and ethylene glycol (EG) is pressurized to 1.5 ~ 2.5kg / ㎠ using nitrogen (N ₂ ) gas while the continuous polyester heating starts to melt the waste polyester flakes at about 210 ℃ When the temperature rises continuously and rises to about 230 ~ 240 ℃, the temperature rise slows down and melting proceeds actively. When the melting proceeds to a certain degree, the mixture should be stirred at 10 to 50 rpm to prevent the carbonization of the compound by concentrating heat energy in one place.

After the melting time of the waste polyester flakes and ethylene glycol (EG) is about 3-4 hours, when the melting is completed, the temperature of the mixture of the waste polyester flakes and ethylene glycol is gradually increased and depolymerization process This is going on.

When the depolymerization process is performed, pressurized to 2.0 ~ 2.5㎏ / ㎠ using nitrogen (N ₂ ) gas, the stirring speed is increased to 20 ~ 60rpm and the temperature is raised to 245 ~ 260 ℃ waste polyester flakes to ethylene glycol Thereby promoting transesterification to produce bis-2-hydroxyethylterephthalate.

In the depolymerization process, after about 1 to 3 hours, the transesterification reaction is completed, so that the waste polyester disappears and only bis-2-hydroxyethyl terephthalate remains. The depolymerization process will most preferably proceed for 2.0 hours at 56 rpm at 255 ℃.

In the second depolymerization process, all or part of the bis-2-hydroxyethyl terephthalate (BHET) generated in the first depolymerization process is mixed with waste polyester flakes and ethylene glycol (EG) to form bis-2-hydroxy. The process of producing ethyl terephthalate (BHET), the depolymerization process after the first depolymerization process, is carried out only by the second depolymerization process using a part of bis-2-hydroxyethyl terephthalate (BHET) produced in the second depolymerization process. You will proceed.

In the second depolymerization process, waste polyester flakes, ethylene glycol (EG), and bis-2-hydroxyethyl terephthalate are mixed at a molar ratio of 1.0: 0.1 to 2.0: 0.5 to 2.0, using nitrogen (N ₂ ) gas, to 1.5. Pressurized to ˜2.5 kg / ㎠ and melted for 30 to 50 minutes by stirring 10 ~ 50rpm at 210 ~ 240 ℃, pressurized to 2.0 ~ 2.5㎏ / ㎠ using nitrogen (N ₂ ) gas and 245 The polymerization condition proceeds in the same manner as the first depolymerization step in the process of depolymerization for 1 to 3 hours while stirring at ˜260 ° C. for 30 to 70 rpm.

In the second depolymerization process, the melting time of the waste polyester flakes is much shorter than that of the first depolymerization process, and bis-2-hydroxyethyl terephthalate catalyzes the reaction time of the transesterification reaction to shorten the entire polymerization process. The time required is drastically shortened and the molecular weight of bis-2-hydroxyethyl terephthalate produced is made uniform.

30 to 60% by weight of the bis-2-hydroxyethyl terephthalate produced in the first and second depolymerization processes is used in the second secondary depolymerization process, and the remaining bis-2-hydroxyethyl terephthalate is used as the reaction tank of the polycondensation process. It is conveyed and polycondensation process is performed.

When transported to the reaction tank of the polycondensation process, bis-2-hydroxyethyl terephthalate is passed through the filter to carry out a filtering process to remove foreign matters and solids generated during the depolymerization reaction when the waste polyester is selected. Therefore, it would be desirable to reduce the productivity of the recycled polyester in the polycondensation process and to prevent elements that inhibit physical properties.

In the filtering process, it is preferable to use a filter of about 300 to 1500 Mesh, and can be pressurized to 1.5 ~ 3.0 kg / ㎠ to shorten the filtering process time.

The polycondensation process is a process of adding a phosphorus flame retardant to the produced bis-2-hydroxyethyl terephthalate to produce a polyester, and polymerization is carried out for 60 to 240 minutes while stirring at 30 to 90 rpm at 245 to 290 ° C. under vacuum. The flame retardant produces copolymerized flame retardant polyester.

The phosphorus-based flame retardant is preferably added to 1000 ~ 8000ppm phosphorus content based on bis-2-hydroxyethyl terephthalate. If the content of phosphorus is less than 1000ppm, the effect of flame retardancy is insignificant, and if it exceeds 8000ppm, the improvement of flame retardancy is not great, especially when producing a fiber may be poor in radioactivity.

Moreover, as for phosphorus content of the said phosphorus flame retardant, 9-20 weight% is preferable. When the phosphorus content is 9% by weight or less, the total amount of the phosphorus-based flame retardant may be increased to lower the polymerization of the polyester.

Phosphorus-based flame retardants used in the present invention may be any of those currently sold, but it will be preferable to use aromatic phosphate ester flame retardants.

In the polycondensation process, Sb ₂ O ₃ , titanium oxide, dibutyl tin dilaurate, or the like may be used as the condensation catalyst, and it may be preferable to use Sb ₂ O ₃ .

In addition, phosphoric acid may be added for the thermal stability of bis-2-hydroxyethylterephthalate. It would be preferable to use H ₃ PO ₄ in phosphoric acid.

The H ₃ PO ₄ is preferably added to 100 ~ 200ppm on the basis of bis-2-hydroxyethyl terephthalate at about 260 ℃, Sb ₂ O ₃ is bis-2-hydroxy at about 265 ℃ It is preferable to add 300 to 600ppm based on ethyl terephthalate.

The vacuum state should be carried out step by step as the polycondensation process starts and the temperature rises to about 1.5 mbar or less at about 285 ° C.

In addition, in the polycondensation process, TiO ₂ or SiO ₂ may be added as a quencher to prepare polyester from which light is removed.

TiO ₂ or SiO ₂ is preferably added in an amount of 0.01 to 3% by weight as compared to bis-2-hydroxyethyl terephthalate.

In the method for producing a flame retardant recycled polyester using waste polyester according to the present invention described above, a recycled polyester is prepared by using bis-2-hydroxyethyl terephthalate produced in a first depolymerization process in a second depolymerization process. The depolymerization process proceeds only to the second depolymerization process after the first depolymerization process to produce regenerated polyester with bis-2-hydroxyethyl terephthalate produced by depolymerization.

Regenerated polyester produced by the manufacturing method according to the present invention can be produced in a chip for ease of use and the size of the chip may be produced in various sizes depending on the industrial field used.

The regenerated polyester produced by the above production method has excellent flame retardancy with a LOI (limiting oxygen index) of 28 or more due to physical properties of intrinsic viscosity (IV) 0.60 to 0.70 dl / g and melting point (Tm) of 240 to 260 ° C. L * is 40-70, b * is 2-8, and the moisture content of polyester is 1wt% or less, and it is possible to manufacture recycled polyester having excellent physical properties.

The present invention recovers high-quality bis-2-hydroxyethyl terephthalate from waste polyester and shortens the time required for the subsequent depolymerization process by using a part of the recovered bis-2-hydroxyethyl terephthalate for depolymerization. This shortens the production time of the regenerated polyester.

In addition, the phosphorus-based flame retardant is added to the polycondensation process, and the polyester and the flame retardant are copolymerized so that the uniform flame retardant is excellent in flame retardancy and permanent flame retardancy.

In addition, the flame-retardant regenerated polyester production method using waste polyester according to the present invention is carried out in a separate polymerization tank and depolymerization process in a separate reaction tank, the difference in the time required of each process is less continuous continuous circulation process in each reactor It is possible and automated to increase the productivity and reduce the production cost of flame retardant recycled polyester.

Examples of the method for producing the recycled polyester fiber of the present invention are shown below, but not limited thereto.

Example 1

The collected waste polyester is sorted and pulverized into flakes having a size of 2-3 mm, and the waste polyester flakes and ethylene glycol (EG) are mixed in a molar ratio of 1.0: 0.5 by a first depolymerization process and nitrogen (N ₂ ) gas is mixed. After pressurizing to 2.0kg / ㎠ and completely melted by stirring at 25 ~ 240 ℃ 25rpm, the molten mixture was pressurized to 2.0kg / ㎠ using nitrogen (N ₂ ) gas and stirred at 245 ~ 260 ℃ 55rpm Depolymerization was carried out to prepare bis-2-hydroxyethyl terephthalate.

In the second depolymerization process, waste polyester flakes, ethylene glycol (EG), and bis-2-hydroxyethyl terephthalate prepared in the first depolymerization process were mixed in a molar ratio of 1.0: 0.5: 1.2 and nitrogen (N ₂ ) gas was used. After pressurizing to 2.0kg / ㎠ and completely melted by stirring 20rpm at 210 ~ 240 ℃, the molten mixture was pressurized to 2.0kg / ㎠ using nitrogen (N ₂ ) gas and stirred at 245 ~ 260 ℃ 58rpm Depolymerized to prepare bis-2-hydroxyethyl terephthalate.

Phosphorus-based flame retardant was added to bis-2-hydroxyethyl terephthalate prepared in the second depolymerization process, and H ₃ PO ₄ was added to 150 ppm based on bis-2-hydroxyethyl terephthalate at a reaction temperature of 260 ° C. On the basis of the bis-2-hydroxyethyl terephthalate (BHET) at a reaction temperature of 265 ° C, 300 ppm of Sb ₂ O ₃ was added to polycondensate to prepare a recycled polyester.

The phosphorus flame retardant was added so that the phosphorus content was 2000 ppm based on bis-2-hydroxyethyl terephthalate using a phosphorus flame retardant having a phosphorus content of 14.1 wt%.

Example 2

In the depolymerization step, the second depolymerization step and the polycondensation step were carried out in the same manner as in Example 1 using bis-2-hydroxyethyl terephthalate prepared in the first depolymerization step in Example 1.

However, a phosphorus flame retardant is added to the polycondensation process so that the phosphorus content is 4000 ppm based on bis-2-hydroxyethyl terephthalate, and 0.03 weight of TiO ₂ is compared with bis-2-hydroxyethyl terephthalate as a matting agent. Regenerated polyester was prepared by carrying out a polycondensation step by further adding%.

Comparative Example 1

Regenerated polyester was prepared in the same manner as in Example 2, but no phosphorus-based flame retardant was added.

Comparative Example 2

Bis-2-hydroxyethyl terephthalate (BHET) was produced only by the first depolymerization process of Example 1, and regenerated polyester was produced by the same polycondensation process.

* Property and color experiment

Flame-retardant regenerated polyester prepared in the above Examples and Comparative Examples were prepared in the form of chips to measure the physical properties of the intrinsic viscosity (IV) and the melting point (Tm) by a conventional method. The values of L * and b * were measured by the methods of ASTM E398-90 and E805-93.

In addition, the limit oxygen index (LOI) of the polyester chips of Examples and Comparative Examples was measured by the KS M 3032 method.

In addition, the time required for the depolymerization process of the embodiments was measured the time required for the second depolymerization process, and the physical properties and color with the polyester chip recycled with bis-2-hydroxyethyl terephthalate (BHET) produced by the second depolymerization process The experiment was conducted.

Comparative Example 2 measured the physical properties and colors of the general polyester fiber chip in the same manner as described above.

The above measured values are shown in Table 1.

division IV
(dl / g) Tm (占 폚) L * b * LOI Depolymerization Process
Required time (min) Polycondensation process
Required time (min) Example 1 0.659 231.2 41.5 7.6 32 161 146 Example 2 0.662 234.4 43.5 8.0 35 165 143 Comparative Example 1 0.659 241.1 42.9 8.4 23 159 146 Comparative Example 2 0.681 245.4 47.4 5.7 20 324 164 Comparative Example 3 0.664 252.9 55.0 11.4 22 - -

As shown in Table 1, the limit oxygen index (LOI) of the comparative examples was 20 to 23, but the general oxygen value was shown, but the limit oxygen index (LOI) of Examples 1 and 2 according to the present invention was 32, 35, and was flame retardant. It turns out that this is excellent.

In addition, the process time of the regenerated polyester of Example 1, Example 2, and Comparative Example 1 through the first secondary depolymerization is shortened by about 150 minutes than the process time of Comparative Example 2, in particular, the time required and depolymerization of the depolymerization process The difference in the time required for the synthesizing process is about 10-20 minutes, and the reaction tank of the polycondensation process waits very little, so that a continuous circulation process is possible.

Claims (14)

In the method for producing flame-retardant recycled polyester by depolymerizing the waste polyester flakes,
Mixing the waste polyester flakes and ethylene glycol (EG) in a molar ratio of 1.0: 0.1 ~ 0.5, pressurized to 1.5 ~ 2.5kg / ㎠ using nitrogen (N 2) gas and stirred at 10 ~ 50rpm at 210 ~ 240 ℃ 3 ~ After melting for 4 hours, the molten mixture was pressurized to 2.0 to 2.5 kg / cm 2 using nitrogen (N 2) gas, and depolymerized for 1.0 to 3.0 hours while stirring at 245 to 260 ° C. for 30 to 70 rpm, followed by bis-2-hydride. A first depolymerization process for producing oxyethyl terephthalate (BHET);
All or part of the bis-2-hydroxyethyl terephthalate (BHET) produced in the first depolymerization process is mixed with waste polyester flakes and ethylene glycol (EG), wherein the waste polyester flakes and the ethylene glycol (EG ) And the bis-2-hydroxyethyl terephthalate in a molar ratio of 1.0: 0.1 to 0.5: 0.5 to 2.0, pressurized to 1.5 to 2.5 kg / cm 2 using nitrogen (N2) gas, and then to 10 to 210 to 240 ° C. After stirring for 50 to 50 minutes by stirring at 50 rpm, the molten mixture was pressurized to 2.0 to 2.5 kg / cm 2 using nitrogen (N 2) gas and depolymerized for 1.0 to 3.0 hours while stirring at 245 to 260 ° C. for 30 to 70 rpm. Secondary depolymerization process to produce bis-2-hydroxyethyl terephthalate (BHET);
A filtering step of removing foreign matter through a filter when the bis-2-hydroxyethyl terephthalate produced by the first depolymerization process or the second depolymerization process is transferred to a polycondensation reaction tank; And
The phosphorus flame retardant is mixed with the bis-2-hydroxyethyl terephthalate (BHET) in a separate reaction tank from the first depolymerization process or the second depolymerization process and stirred at 30 to 90 rpm at 245 to 290 ° C. for 60 to 240 minutes. Polycondensation step of polymerization to produce regenerated polyester;
A method for producing a flame retardant recycled polyester using waste polyester, characterized in that the secondary depolymerization process is performed using only a part of bis-2-hydroxyethyl terephthalate (BHET) produced in the secondary depolymerization process. delete delete delete The method of claim 1,
Method for producing a flame retardant recycled polyester using waste polyester, characterized in that H ₃ PO ₄ , Sb ₂ O ₃ is used as the polycondensation reaction catalyst in the polycondensation process. The method of claim 5,
Based on the bis-2-hydroxyethyl terephthalate, H ₃ PO ₄ is 100 ~ 200ppm, Sb ₂ O ₃ 300 ~ 600ppm The method for producing a flame retardant recycled polyester using waste polyester, characterized in that the addition. The method of claim 1,
In the polycondensation process, 0.01 to 3% by weight of TiO ₂ or SiO ₂ is added to the polycondensation agent as compared to bis-2-hydroxyethyl terephthalate to polycondensate. . The method of claim 1,
The phosphorus-based flame retardant is a flame retardant recycled polyester production method using waste polyester, characterized in that the content of phosphorus 1000 ~ 8000ppm is added on the basis of bis-2-hydroxyethyl terephthalate. The method of claim 1,
A method for producing a flame retardant recycled polyester using waste polyester, characterized in that the phosphorus content of the phosphorus flame retardant is 9 to 20% by weight. delete A flame retardant regenerated polyester using waste polyester, characterized in that it is produced by the method of any one of claims 1, 5, 6, 7, 8, and 9. The method of claim 11,
The flame retardant regenerated polyester has physical properties of intrinsic viscosity (IV) 0.65-0.70 dl / g, acid value (-COOH) 5-45 eq / ton, melting point (Tm) 220-250 ° C., limit oxygen index (LOI) of 28 or more Flame retardant regenerated polyester using waste polyester characterized by the above-mentioned. The method of claim 11,
The flame retardant regenerated polyester is L * is 40 to 70, b * is flame retardant regenerated polyester using waste polyester, characterized in that 2 to 8. The method of claim 11,
The flame retardant regenerated polyester is flame retardant regenerated polyester using waste polyester, characterized in that the moisture content is 1wt% or less.