KR101180389B1 - Recycled polyester chip using waste polyester and method thereof - Google Patents

Abstract

The present invention provides a method for producing a recycled polyester chip using waste polyester, comprising: a waste polyester flake process of sorting the waste polyester and pulverizing it into flakes; The waste polyester flakes and ethylene glycol (EG) are mixed at a molar ratio of 1.0: 0.1 to 2.0, pressurized at 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas, and stirred by melting at 10 to 50 rpm at 210 to 240 ° C. Mixed melting process; The mixture was pressurized to 2.0 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas and depolymerized at 245 to 260 ° C. at 20 to 60 rpm for 1.0 to 3.0 hours to obtain bis-2-hydroxyethyl terephthalate (BHET). Depolymerization process to produce; A filtering step of removing foreign matter through a filter of bis-2-hydroxyethyl terephthalate (BHET) produced by the depolymerization process; A polycondensation step of polymerizing the bis-2-hydroxyethyl terephthalate (BHET) for 60 to 240 minutes while stirring at 30 to 90 rpm at 245 to 290 ° C. in a vacuum state to produce a polyester; It provides a recycled polyester chip production method using waste polyester, characterized in that it comprises a chip manufacturing step of producing a recycled polyester produced by the polymerization process into a chip.

Polyester, depolymerization, bis-2-hydroxyethyl terephthalate, polycondensation

Description

Recycled polyester chip using waste polyester and manufacturing method thereof {RECYCLED POLYESTER CHIP USING WASTE POLYESTER AND METHOD THEREOF}

The present invention is to separate the bis-2-hydroxyethyl terephthalate (BHET) from waste polyester by using ethylene glycol, and to separate the polyester chip with bis-2-hydroxyethyl terephthalate (BHET) and a method of manufacturing the same. It is about.

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 for general purpose. There was a limit to use in industry because of poor characteristics.

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. Public opinion on environmental pollution has begun to emerge in Korea, and a plan for economic recovery and recycling of waste resources has been established, and related research is being progressed.

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, terephthalate 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.

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, An object of the present invention is to provide a production method for producing a recycled polyester chip having excellent physical properties by re-polymerizing the recovered bis-2-hydroxyethyl terephthalate.

The present invention provides a method for producing a recycled polyester chip using waste polyester, comprising: a waste polyester flake process of sorting the waste polyester and pulverizing it into flakes; The waste polyester flakes and ethylene glycol (EG) are mixed at a molar ratio of 1.0: 0.1 to 2.0, pressurized at 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas, and stirred by melting at 10 to 50 rpm at 210 to 240 ° C. Mixed melting process; The mixture was pressurized to 2.0 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas and depolymerized at 245 to 260 ° C. at 20 to 60 rpm for 1.0 to 3.0 hours to obtain bis-2-hydroxyethyl terephthalate (BHET). Depolymerization process to produce; A filtering step of removing foreign matter through a filter of bis-2-hydroxyethyl terephthalate (BHET) produced by the depolymerization process; A polycondensation step of polymerizing the bis-2-hydroxyethyl terephthalate (BHET) for 60 to 240 minutes while stirring at 30 to 90 rpm at 245 to 290 ° C. in a vacuum state to produce a polyester; It provides a recycled polyester chip production method using waste polyester, characterized in that it comprises a chip manufacturing step of producing a recycled polyester produced by the polymerization process into a chip.

In addition, a bis-2-hydroxyethyl terephthalate (BHET) in the mixing step is to provide a method for producing a recycled polyester chip using the waste polyester, characterized in that further mixing.

In addition, the bis-2-hydroxyethyl terephthalate (BHET) provides a method for producing a recycled polyester chip using waste polyester, characterized in that 0.01 to 1.0 mole is mixed with respect to 1 mole of waste polyester flakes.

In addition, the waste polyester flakes and ethylene glycol (EG) in the mixing step provides a method for producing a recycled polyester chip using the waste polyester, characterized in that for mixing.

In addition, the depolymerization process provides a method for producing a recycled polyester chip using waste polyester, characterized in that carried out at 255 ℃ for 56 hours at 56 rpm.

The present invention also provides a method for producing a recycled polyester chip 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, based on the bis-2-hydroxyethyl terephthalate (BHET), H ₃ PO ₄ is 100 ~ 200ppm, Sb ₂ O ₃ 300 ~ 600ppm is added, the method of producing a recycled polyester chip To provide.

In addition, the present invention provides a recycled polyester chip using waste polyester, characterized in that the manufacturing method.

In addition, the recycled polyester chip is a waste poly, characterized by having physical properties of intrinsic viscosity (IV) of 0.60 to 0.70 dl / g, acid value (-COOH) of 5 to 45 eq / ton, and melting point (Tm) of 240 to 260 ° C. It provides a recycled polyester chip using an ester.

In addition, the regenerated polyester chip provides a regenerated polyester chip using the waste polyester, characterized in that the color L * is 45 ~ 55, b * is 2 ~ 8.

In addition, the regenerated polyester chip provides a regenerated polyester chip using the 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 to or in the numerical value of the 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.

1 is a schematic process diagram of a method for producing a recycled polyester chip using waste polyester according to the present invention, as shown in FIG. 1, the present invention is a waste polyester flake process, a mixed melting process, a depolymerization process, a filtering process, and a polycondensation. Regenerated polyester chips are manufactured by combining process and chip manufacturing process.

Each process of the above will be described in detail as follows.

In the waste polyester flake process, waste polyester flakes are removed by pulverizing waste polyester flakes having a flake shape of 1 to 20 mm using a grinder or the like from metals and synthetic resins having different components. Manufacture.

The waste polyester flakes may be finely pulverized to 1 to 5 mm to be easily melted.

In the mixed melting process, the waste polyester flakes are melted to allow ethylene glycol to react and mixed with ethylene glycol. The waste polyester flakes and ethylene glycol are mixed in a molar ratio of 1.0: 0.1 to 2.0 and nitrogen (N ₂ ) gas. It is continuously heated and melted while pressurizing at 1.5 to 2.5 kg / cm 2.

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

The ethylene glycol decomposes the polyester into bis-2-hydroxyethyl terephthalate by depolymerization by using a waste polyester and a transesterification reaction as in Scheme 1 above.

The reaction rate of the depolymerization of the present invention depends on the temperature, catalyst, feedstock granularity and the amount of glycol. The final monomer composition is also determined by the decomposition reaction time and the duration after depolymerization. Lower amounts of glycol require higher temperatures and longer reaction times, resulting in higher molecular weight oligomers.

Therefore, when less than 0.1 mol of ethylene glycol is mixed with respect to 1 mol of the waste polyester flakes, the reaction time becomes too long, and when mixed with 2.0 mol or more, the shortening effect of the reaction time is not large. Most preferably, the ethylene glycol is mixed in a waste polyester flake molar ratio of 1.0: 0.3.

In addition, by using bis-2-hydroxyethyl terephthalate as a catalyst in the mixing step, the reaction time of the transesterification reaction can be shortened, and the molecular weight of bis-2-hydroxyethyl terephthalate produced by the depolymerization process can be made uniform. have.

When using the bis-2-hydroxyethyl terephthalate as a catalyst, it will be preferable to further mix 0.05 to 1.0 mole with respect to 1 mole of waste polyester.

In the mixed melting process, the melted polyester flakes start melting at about 210 ° C. by continuous heating, and the temperature rises continuously, and when the temperature rises to about 230 ° C. to 240 ° C., the melting increases as the temperature rises.

In the mixed melting process, the stirring should be carried out to 10 ~ 50rpm after the melting to some extent to prevent the heat energy concentrated in one place.

When melting is completed in the mixed melting process, when the temperature of the mixture of the waste polyester flake and ethylene glycol is gradually increased, the depolymerization process is performed.

When the depolymerization process proceeds, 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 ℃.

The depolymerization process may be performed in a continuous process by proceeding the two processes in the same place to proceed simultaneously with the end of the melting of the mixed melting process waste polyester flakes.

The filtering process is a process of removing bis-2-hydroxyethyl terephthalate produced by the depolymerization process through a filter to remove bis-2-hydroxyethyl terephthalate that has not been removed in the screening process and then purifying bis-2-hydroxyethyl terephthalate. It is a process for reducing the productivity and the defective rate of a recycled polyester in the polycondensation process performed.

In the filtering process, the filter preferably uses a filter of about 300 to 1500 Mesh, and may be pressurized to 1.5 to 3.0 kg / cm 2 to shorten the filtering process time.

The polycondensation process is a process for producing polyester with the bis-2-hydroxyethyl terephthalate. In general, the polycondensation process is carried out by polymerization at 60 to 240 minutes while stirring at 30 to 90 rpm at 245 to 290 ° C. in a vacuum state. Generate recycled polyester.

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 at about 260 ℃ about 100 ~ 200ppm based on the service-2-hydroxyethyl terephthalate, Sb ₂ O ₃ is bis-2-hydride at about 265 ℃ It is preferable to add 300-600 ppm based on oxyethyl 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.

The chip manufacturing process is a process of manufacturing the chip to facilitate the use of the recycled polyester produced by the polycondensation process, the size of the chip may be produced in various sizes depending on the industrial field used.

The recycled polyester chip manufactured by the above method has physical properties of intrinsic viscosity (IV) 0.60 to 0.70 dl / g, acid value (-COOH) 5 to 45 eq / ton, melting point (Tm) 240 to 260 ° C, The recycled polyester chip has a color of L * of 45 ~ 55 and b * of 2 ~ 8, and a moisture content of 1wt% or less can make polyester products of excellent physical properties.

The present invention depolymerizes waste polyester without bis-2-hydroxyethyl terephthalate without catalyst and polycondenses the produced bis-2-hydroxyethyl terephthalate to prepare recycled polyester to terephthalic acid, dimethyl terephthalate and ethylene glycol. It is simpler than the process of making recycled polyester by depolymerization, and it has the effect of shortening the production time of the recycled polyester. The properties of the recycled polyester chip have excellent properties that are inferior to those of general polyester chips. It works.

In addition, by recycling waste polyester, which was difficult to dispose, there is an effect of saving resources and protecting the environment.

In addition, the method for producing a recycled polyester chip using waste polyester according to the present invention can perform a batch or continuous process to automate all processes to increase productivity and reduce production costs.

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 pulverized waste flakes and ethylene glycol (EG) are mixed in a molar ratio of 1.0: 0.1 and nitrogen (N ₂ ) gas is used. Pressurized to 2.0 kg / ㎠ and continuously heated to 18rpm stirred at 230 ~ 240 ℃ was continuously heated until the complete melt of the polyester flakes.

The molten mixture was pressurized to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas and continuously heated to 255 ° C. and depolymerized at 56 rpm to produce bis-2-hydroxyethyl terephthalate (BHET). The depolymerization process was performed.

The foreign substance was removed from the bis-2-hydroxyethyl terephthalate (BHET) through a filter, and the bis-2-hydroxyethyl terephthalate (BHET) was continuously heated in a vacuum to raise the temperature to 285 ° C. and at 60 rpm. Polycondensation was carried out for 60 minutes with stirring to produce a polyester, which was prepared as a regenerated polyester chip.

In the polycondensation process, H ₃ PO ₄ was added to 150 ppm based on bis-2-hydroxyethyl terephthalate (BHET) at a reaction temperature of 260 ° C., and bis-2-hydroxyethyl terephthalate at a reaction temperature of 265 ° C. 300 ppm of Sb ₂ O ₃ was added based on (BHET).

Example 2

In the mixing melting process, waste polyester flakes and ethylene glycol (EG) were mixed in a molar ratio of 1.0: 0.5, and were carried out in the same manner as in Example 1 to prepare a recycled polyester chip.

Example 3

In the mixing melting process, waste polyester flakes and ethylene glycol (EG) were mixed in a molar ratio of 1.0: .075, which was carried out in the same manner as in Example 1 to prepare a recycled polyester chip.

Example 4

In the mixing melting process, waste polyester flakes and ethylene glycol (EG) were mixed in a molar ratio of 1.0: 1.0, and were carried out in the same manner as in Example 1 to prepare a recycled polyester chip.

Example 5

In the mixing melting process, waste polyester flakes and ethylene glycol (EG) were mixed in a molar ratio of 1.0: 1.5, and the same procedure as in Example 1 was carried out to prepare a recycled polyester chip.

Example 6

Bis-2-hydroxyethyl terephthalate was further added in the mixing melting process. Waste polyester flakes, ethylene glycol and bis-2-hydroxyethyl terephthalate were mixed in a molar ratio of 1.0: 0.5: 0.05, and the same procedure as in Example 1 was carried out to prepare a recycled polyester chip.

Example 7

Bis-2-hydroxyethyl terephthalate was further added in the mixing melting process. Waste polyester flakes, ethylene glycol and bis-2-hydroxyethyl terephthalate were mixed in a molar ratio of 1.0: 1.0: 0.05 and carried out in the same manner as in Example 1 to prepare a recycled polyester chip.

Example 8

Bis-2-hydroxyethyl terephthalate was further added in the mixing melting process. Waste polyester flakes, ethylene glycol and bis-2-hydroxyethyl terephthalate were mixed in a molar ratio of 1.0: 1.0: 0.5 in the same manner as in Example 1 to prepare a recycled polyester chip.

Example 9

Bis-2-hydroxyethyl terephthalate was further added in the mixing melting process. Waste polyester flakes, ethylene glycol and bis-2-hydroxyethyl terephthalate were mixed in a molar ratio of 1.0: 1.0: 1.0 in the same manner as in Example 1 to prepare a recycled polyester chip.

* Property and color experiment

The regenerated polyester chips prepared according to the above examples were measured by the conventional method in terms of intrinsic viscosity (IV), acid value (-COOH) and melting point (Tm), and the color of the regenerated polyester chip was measured. The values of L * and b * were measured by the methods of E398-90 and E805-93 of ASTM.

In addition, the depolymerization time was measured when the depolymerization process is completed when the temperature rises in the mixed melting process.

As a comparative example, the physical properties and color of the polyester fiber chip were measured in the same manner as described above.

The above measured values are shown in Table 1.

division IV
(dl / g) -COOH
(ed / ton) Tm (占 폚) L * b * Depolymerization time
(min) Example 1 0.715 36.3 242.8 44.8 7.6 136 Example 2 0.687 37.1 244.1 47.4 5.7 129 Example 3 0.675 38.2 244.2 49.2 4.1 121 Example 4 0.680 38.4 244.7 48.6 4.3 119 Example 5 0.682 39.1 244.6 47.6 3.2 117 Example 6 0.692 38.8 247.0 48.2 5.3 113 Example 7 0.677 38.2 248.3 49.6 4.9 113 Example 8 0.697 39.4 247.7 50.1 5.0 111 Example 9 0.704 42.1 250.2 53.3 5.4 109 Comparative example 0.664 47.2 252.9 55.0 11.4 -

As shown in Table 1, it can be seen that the physical properties of the recycled polyester chip produced by the waste polyester chip manufacturing method according to the present invention are not significantly different from the example chip.

In addition, it can be seen that the depolymerization time is shortened due to the high content of ethylene glycol, and the depolymerization time is further shortened when bis-2-hydroxyethyl terephthalate is added.

1 is a schematic process diagram of a method for producing a recycled polyester chip using waste polyester according to the present invention.

Claims (11)

In the method for producing a recycled polyester chip using waste polyester, Waste polyester flake process of sorting waste polyester and grinding it into flakes; The waste polyester flakes, ethylene glycol (EG) and bis-2-hydroxyethyl terephthalate were mixed in a molar ratio of 1.0: 0.1 to 0.5: 0.01 to 1.0, and 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas. Mixed melt process to pressurize and melt by stirring 10 ~ 50rpm at 210 ~ 240 ℃; 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 2 hours while stirring at 245 to 260 ° C. for 20 to 60 rpm, followed by bis-2-hydroxyethyl terephthalate ( Depolymerization process to produce BHET); A filtering step of removing foreign substances by pressing bis-2-hydroxyethyl terephthalate produced by the depolymerization process using a 300 to 1500 Mesh filter and then pressing to 1.5 to 3.0 kg / cm 2; A polycondensation step of polymerizing the bis-2-hydroxyethyl terephthalate at 60 to 240 minutes while stirring at 30 to 90 rpm at 245 to 290 ° C. in a vacuum state to produce a polyester; Method for producing a recycled polyester chip using waste polyester, characterized in that it comprises a chip manufacturing step of producing a recycled polyester produced by the polymerization process into a chip. delete delete delete The method of claim 1, The depolymerization process is a method for producing a recycled polyester chip using waste polyester, characterized in that carried out for 2 hours at 56 rpm at 255 ℃. The method of claim 1, In the polycondensation process, H ₃ PO ₄ , Sb ₂ O ₃ is used as a polycondensation reaction catalyst. The method of claim 6, Based on the bis-2-hydroxyethyl terephthalate, H ₃ PO ₄ is 100 ~ 200ppm, Sb ₂ O _{3 The} regenerated polyester chip manufacturing method characterized in that the addition. A regenerated polyester chip using waste polyester, characterized in that it is produced by the method of any one of claims 1, 5, 6 and 7. 9. The method of claim 8, The recycled polyester chip is a waste polyester characterized by having physical properties of intrinsic viscosity (IV) of 0.65 to 0.70 dl / g, acid value (-COOH) of 5 to 45 eq / ton, and melting point (Tm) of 240 to 260 ° C. Recycled polyester chip using. 9. The method of claim 8, The regenerated polyester chip is a color polyester L * 45 ~ 55, b * is a recycled polyester chip using waste polyester, characterized in that 2 to 8. 9. The method of claim 8, The regenerated polyester chip is a regenerated polyester chip using waste polyester, characterized in that the moisture content is 1wt% or less.

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