KR101306581B1 - Manufacturing method of regenerated polyester using waste polyester and regenerated polyester obtained therefrom - Google Patents

Abstract

The present invention depolymerizes waste polyester using ethylene glycol as a depolymerization catalyst to produce bis-2-hydroxyethyl terephthalate (BHET) as an intermediate, and generates bis-2-hydroxyethyl terephthalate (BHET). Modification with waste polyester to add a modifying agent for modifying the polyester obtained in condensation again to obtain a regenerated polyester having the same or similar physical properties of the new polyester, and to condense to obtain a modified polyester. A method for producing a polyester, comprising depolymerizing waste polyester with bis-2-hydroxyethyl terephthalate (BHET), and then polycondensing the bis-2-hydroxyethyl terephthalate to produce a polyester. (1) Ethylene Glycol as Catalyst and Solvent in the Production Process of Ester Call; mixing step of mixing the (EG ethylene glycol) to give a first mixture; (2) a melting step of melting the waste polyester in the first mixture; (3) depolymerization of the molten first mixture to produce bis-2-hydroxyethyl terephthalate (BHET); And (4) a polycondensation step of mixing and modifying the bis-2-hydroxyethyl terephthalate in an amount of 1 to 25 parts by weight based on the total polyester weight (100 parts by weight), and polycondensing the bis-2-hydroxyethyl terephthalate. It is done.

Description

Manufacturing Method of Modified Polyester Using Waste Polyester and Modified Polyester Obtained Therefrom {MANUFACTURING METHOD OF REGENERATED POLYESTER USING WASTE POLYESTER AND REGENERATED POLYESTER OBTAINED THEREFROM}

The present invention depolymerizes waste polyester using ethylene glycol as a depolymerization catalyst to produce bis-2-hydroxyethyl terephthalate (BHET) as an intermediate, and generates bis-2-hydroxyethyl terephthalate (BHET). Modification with waste polyester to add a modifying agent for modifying the polyester obtained in condensation again to obtain a regenerated polyester having the same or similar physical properties of the new polyester, and to condense to obtain a modified polyester. It relates to a method for producing a polyester.

As incomes rise and living standards rise, the amount of waste generated increases, causing serious environmental pollution. In particular, waste synthetic resins account for about 15% of household waste, but many of them are foam-molded or hollow-molded, and they occupy much more volume.Incineration generates various harmful gases, which cause smog, and they do not decompose even when landfilled. There are disadvantages.

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 have difficulty in generalization because they are 5 to 10 times more expensive than ordinary synthetic resins. 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, studies on recovery and recycling of useful resources from wastes under long-term planning have been pursued in many ways. 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 synthetic resin in fibers, films, food containers, etc., and waste polyester generated during the manufacturing of the above-mentioned articles, ie, fibers, films, food containers, etc. The recycling of waste such as waste polyester such as drinking water bottles is a big concern.

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

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

In addition, in general, the depolymerization is performed by mixing and melting waste polyester and ethylene glycol to perform depolymerization, but the conventional depolymerization using ethylene glycol as a catalyst and solvent is the same as that of the original waste polyester used for depolymerization or It is merely to provide a general polyester that is obtained to a similar degree and not greatly improved in terms of physical properties, and therefore, there is a need for a technique capable of modifying a polyester obtained through condensation after such depolymerization to have a desired physical property.

The present invention has been invented to solve the above problems, by collecting the discarded waste polyester to recover the good bis-2-hydroxyethyl terephthalate from the waste polyester through depolymerization, recovered Bis-2 Modification with waste polyester to produce a polyester through polycondensation reaction using hydroxyethyl terephthalate, adding a modifying agent for modifying the obtained polyester, and condensing to obtain a modified polyester. It is an object to provide a method for producing a polyester.

It is also an object of the present invention to provide a modified polyester having a good effect in terms of low melting point, dyeing property, etc., with the newly produced polyester produced by a general manufacturing method.

According to one embodiment of the present invention, depolymerized waste polyester with bis-2-hydroxyethyl terephthalate (BHET), and then polycondensation of the bis-2-hydroxyethyl terephthalate to prepare a polyester. A method for producing a polyester, the method comprising: (1) mixing a waste polyester with ethylene glycol (EG) as a catalyst and a solvent to obtain a first mixture; (2) a melting step of melting the waste polyester in the first mixture; (3) depolymerization of the molten first mixture to produce bis-2-hydroxyethyl terephthalate (BHET); And (4) a polycondensation step of mixing and modifying the bis-2-hydroxyethyl terephthalate in an amount of 1 to 25 parts by weight based on the total polyester weight (100 parts by weight), and polycondensing the bis-2-hydroxyethyl terephthalate. Provided is a method for producing a modified polyester using waste polyester.

The modifier may preferably be polyethylene glycol (PEG), dimethyl-5-sulfoisophthalate sodium salt (DMS), isophthalic acid (IPA) or a mixture of two or more thereof.

The polycondensation step may be performed by heating the bis-2-hydroxyethyl terephthalate at a temperature range of 245 to 290 ° C. for 60 to 240 minutes while stirring at 30 to 90 rpm in a vacuum state.

According to another embodiment of the present invention, there is provided a modified polyester, characterized in that it is prepared according to the method for producing a modified polyester.

According to the present invention, depolymerized waste polyester using ethylene glycol as depolymerization catalyst to produce bis-2-hydroxyethyl terephthalate (BHET) as an intermediate, and the resulting bis-2-hydroxyethyl terephthalate (BHET). ) Polycondensation again to obtain a recycled polyester having the same or similar physical properties of the new polyester, adding a modifier for modifying the polyester obtained and polycondensing to obtain a modified polyester. It provides a process for producing a modified polyester using an ester, and also has the effect of providing a modified polyester obtained therefrom.

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

Hereinafter, preferred embodiments 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.

Chemically recyclable polyesters include hydrolysis, which uses water to reduce monomers or oligomers, glycols such as ethylene glycol (EG) and propylene glycol (PG). And glycolysis using methanol, 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 relates to a method of obtaining a modified polyester through the addition of a modifier and polycondensation in obtaining.

In the method for producing a modified polyester according to the present invention, after depolymerizing waste polyester with bis-2-hydroxyethyl terephthalate (BHET), the bis-2-hydroxyethyl terephthalate is polycondensed to obtain a polyester. A method for producing a polyester, comprising: (1) mixing a waste polyester with ethylene glycol (EG; ethylene glycol) as a catalyst and a solvent to obtain a first mixture; (2) a melting step of melting the waste polyester in the first mixture; (3) depolymerization of the molten first mixture to produce bis-2-hydroxyethyl terephthalate (BHET); And (4) a polycondensation step of mixing and modifying the bis-2-hydroxyethyl terephthalate in an amount of 1 to 25 parts by weight based on the total polyester weight, and polycondensing the bis-2-hydroxyethyl terephthalate.

The mixing step of (1) consists of mixing the waste polyester with ethylene glycol (EG; ethylene glycol) as a catalyst and solvent to obtain a first mixture. The waste polyester is a metal component, a synthetic resin of different components, etc. is removed from the collected waste polyester, and the waste polyester is pulverized into a flake shape having a size in the range of 1 to 20 mm using a pulverizer. The waste polyester may be finely pulverized to a size in the range of 1 to 5 mm to be easily melted, but the present invention is not limited to the flake shape as described above or the range of the size of the bar.

The melting step of (2) consists of allowing the waste polyester in the first mixture to react well with ethylene glycol as a catalyst and solvent as described above to promote depolymerization.

The depolymerization step of (3) consists of depolymerizing the molten first mixture to produce bis-2-hydroxyethyl terephthalate (BHET). In the depolymerization step, the ethylene glycol decomposes the polyester into bis-2-hydroxyethyl terephthalate by depolymerization by a transesterification reaction with the waste polyester. 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. In the depolymerization, in particular, the first mixture obtained by mixing the waste polyester and ethylene glycol (EG) in a molar ratio of 1.0: 0.1 to 2.0 is pressurized to 1.5 to 2.5 kg / cm 2 using nitrogen (N ₂ ) gas, and 210 to Melt for 3 to 4 hours while stirring at 240 ℃ 10 to 50 rpm, pressurized to 2.0 to 2.5 kg / ㎠ using nitrogen gas, 100 to 100 with stirring at a rate of 30 to 70 rpm at 225 to 260 ℃ Depolymerization for 180 minutes. The mixing ratio of the waste polyester and ethylene glycol may have a problem that the reaction time is too long when ethylene glycol is mixed with less than 0.1 mole with respect to 1 mole of the waste polyester, on the contrary, when it exceeds 2.0 moles, The amount of waste polyester administered to the depolymerization in the reaction vessel having an inner volume is reduced to reduce the productivity, there may be a problem that a relatively excessive energy is required for the depolymerization of the same amount of waste polyester. In the mixed waste polyester and ethylene glycol, the melted polyester starts to melt at about 210 ° C. by heating, and when the temperature is continuously increased to 230 to 240 ° C., the melting increases as the temperature rises. When the melting proceeds to some extent, the mixture is stirred at 10 to 50 rpm to prevent the carbonization of the compound by concentrating thermal energy in one place. After the melting time of the waste polyester and ethylene glycol is about 3 to 4 hours, the melting is completed, after the melting of the waste polyester is completed, pressurized to 2.0 to 2.5kg / ㎠ using nitrogen gas, The stirring speed is raised to 20 to 60 rpm and the temperature is raised to 225 to 260 ° C. so that the waste polyester promotes depolymerization through transesterification with ethylene glycol to produce bis-2-hydroxyethyl terephthalate.

After the depolymerization step, a bis-2-hydroxyethyl terephthalate produced in the depolymerization step may be further filtered to remove the foreign matter. The filtering process is a process of removing bis-2-hydroxyethyl terephthalate generated by the depolymerization process through a filter to remove bis-2-hydroxyethyl terephthalate and removing bis-2-hydroxyethyl terephthalate after the filtering process. 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, but the present invention is not limited thereto. It will be understood by those skilled in the art that the selection of an appropriate filter and the appropriate degree of pressurization can be selected in consideration of the source of waste polyester and the degree of contamination of the waste polyester.

In addition, in the polycondensation step (4), a modifier is added to the bis-2-hydroxyethyl terephthalate obtained in the depolymerization step, but mixed in an amount of 1 to 25 parts by weight based on the total polyester weight, and polycondensation thereof. It consists of. The polycondensation step is a step of producing a polyester with the bis-2-hydroxyethyl terephthalate, and the bis-2-hydroxyethyl terephthalate in a vacuum to 30 to the same or similar to the process for producing a general polyester It may consist of heating to a temperature range of 245 to 290 ° C for 60 to 240 minutes while stirring at 90 rpm. In particular, the present invention is characterized in that in the polycondensation step, the bis-2-hydroxyethyl terephthalate is mixed with a modifier and polycondensed. The vacuum state may be adjusted to be about 1.5 mbar or less at about 285 ° C. by performing the step as the polycondensation process starts and the temperature rises. In the polycondensation process, antimony oxide (Sb ₂ O ₃ ), titanium oxide, dibutyl tin dilaurate and the like may be used as the condensation catalyst, and antimony oxide may be preferably used. The antimony oxide may be used in an amount of 50 to 600 ppm based on the total amount of bis-2-hydroxyethyl terephthalate. When the amount of the antimony oxide used as the polycondensation catalyst is less than 50 ppm based on the total amount of bis-2-hydroxyethyl terephthalate, there may be a problem that the reaction rate is significantly lowered, on the contrary, exceeds 600 ppm. In this case, the reaction rate is too fast to increase the molecular weight distribution, and also may cause problems such as increasing the pack pressure by acting as a foreign material during spinning. In addition, the polycondensation step may be performed by adding a thermal stabilizer to the bis-2-hydroxyethyl terephthalate. As the heat stabilizer, phosphoric acid (H ₃ PO ₄ ) may be preferably used. The thermal stabilizer is added for the thermal stability of the bis-2-hydroxyethyl terephthalate. The phosphoric acid may be used in an amount of 100 to 400 ppm based on the total amount of bis-2-hydroxyethyl terephthalate. When the amount of the phosphoric acid used as the thermal stabilizer is less than 100 ppm based on the total amount of bis-2-hydroxyethyl terephthalate, there may be a problem that the heat resistance of the final polymer is lowered, and in contrast, it exceeds 400 ppm. In this case, there may be a problem that acts as a foreign material during spinning to increase the pack pressure, and lower the reaction activity of the catalyst. In the polycondensation step, titanium dioxide (TiO ₂ ) or silicon dioxide (SiO ₂ ) may be further added as a quencher in an amount of 0.01 to 3% by weight based on the total amount of bis-2-hydroxyethyl terephthalate. have.

The modifier may preferably be polyethylene glycol (PEG), dimethyl-5-sulfoisophthalate sodium salt (DMS), isophthalic acid (IPA) or a mixture of two or more thereof. Herein, the modifier may be polyethylene glycol (PEG) alone or may be added together with polyethylene glycol (PEG) and DMS (Dimethyl-5-Sulfoisophthalate Sodium Salt). The DMS is represented by the following Chemical Formula 1.

When the polyethylene glycol alone is added, PEG 1 to 10% by weight may be added based on the total weight of PET to be regenerated, and when polyethylene glycol and DMS are added together, PEG 1 to 10 is based on the total PET weight. Weight percent and 1 to 10 weight percent of DMS can be added. By adding PEG alone or PEG and DMS as the modifier, the dyeing property of PET can be increased to improve the dyeing property of PET. In connection with the improvement of the dyeing property, the cationic dye is bonded to the sulfonic acid group (SO ^3- ) in the DMS, and exhibits excellent color development. In addition, polyethylene glycol is believed to make the molecular chain chain flexible to facilitate dyeing. In addition, isophthalic acid (IPA) may be added together with the PEG as the modifier. When the polyethylene glycol and IPA are added together, 1 to 10% by weight of PEG and 1 to 10% by weight of IPA may be added based on the total PET weight. By adding PEG and IPA as the modifier, the melting point of PET is lowered to prepare modified PET having a lower melting point. Make it possible.

Further, according to the present invention, a post-processing step such as a chip manufacturing step may be further included after the polycondensation step. The chip manufacturing step is a step of manufacturing a recycled polyester produced by the polycondensation process so as to be easy to use. The size of the chip can be produced in various sizes according to the industry in which it is used. Adjustment of the size and shape of the chip and the like can be easily understood by those skilled in the art.

According to the method for producing a modified polyester using waste polyester according to the present invention as described above, according to the type and the amount of the modifiers added in the polycondensation step, the low-melting point properties, the dyeability improved other properties of the modified poly There is an effect that an ester is provided.

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

Comparative example  One

In the preparation of polyester, a low melting point polyester was prepared by adding the modifiers shown in Table 1 below based on one ton of polyester and polycondensing under the addition of the subsidiary materials shown in Table 2 and the polymerization conditions of Table 3 below. Was prepared.

division Weight portion Input (kg) Isophthalic acid 20.2 256 Polyethylene Glycol-4000 0.7 8.7

Esterification temperature 235 ℃ Esterification reaction pressure 2㎏f / ㎠ Esterification reaction time 210 minutes Polycondensation reaction temperature 270 ℃ Polycondensation reaction pressure Vacuum (1 Torr or less) Polycondensation reaction time 210 minutes

division The input Heat stabilizer H ₃ PO ₄ 150ppm Polycondensation Reaction Catalyst Sb ₂ O ₃ 300ppm Matting agent TiO ₂ 3000 ppm

In Table 3 above, the input amount is based on 1 ton of PET.

As a physical property and color test of the low-melting polyester obtained according to the above, the color of the polyester chip was measured by the method of ASTM E398-90 and E805-93 and the values of L * and b *, melting point (Tm) and The content of diethylene glycol (DEG) as a by-product was measured by a conventional method, and the results are shown in Table 4 below.

Example  One

The collected waste polyester is collected and ground to an average size of 2.5 mm, and pulverized into flakes. The pulverized waste polyester and ethylene glycol (EG) are mixed in a molar ratio of 1.0: 0.25, and nitrogen gas is mixed. Pressurized to 2.0 kg / cm 2, and stirred at a rate of 18 rpm at about 235 ° C. to continue heating for about 2 hours until the spent polyester flakes were completely melted. The molten mixture was pressurized to 2.5 kg / cm 2 using nitrogen gas, continuously heated to 255 ° C., and depolymerized with stirring at a speed of 56 rpm to obtain bis-2-hydroxyethyl terephthalate in oligomer form. The foreign material was removed through a filter, and the bis-2-hydroxyethyl terephthalate (BHET) was added to the bis-2-hydroxyethyl terephthalate (BHET) as a modifier, and the modifiers shown in Table 1 of Comparative Example 1 were added and the subsidiary materials shown in Table 2 were added. Polycondensation was carried out under the polymerization conditions of Table 3 to prepare a polyester to obtain a modified low melting point polyester. As a physical property and color test of the modified low-melting point polyester according to the above, the color of the polyester chip was measured by the method of ASTM E398-90 and E805-93 and the values of L * and b *, and the melting point (Tm) And the content of diethylene glycol (DEG) as a by-product, etc. were measured by a conventional method, and the results are shown in Table 4 below.

division Hue L Hue b DEG Tm Comparative Example 1 53.4 2.5 1.6 - Example 1 49.3 3.8 1.9 - * The DEG item means the content of diethylene glycol produced as a reaction by-product.
* The content of DEG is a weight percent based on the total weight of PET.

As shown in Table 4, the modified low-melting polyester obtained according to the method for producing a modified polyester using the waste polyester according to the present invention is significant compared to the low-melting polyester of the new material (Comparative Example 1) There was no significant difference. In Table 4, the melting point was not measured precisely and was not recorded as a specific value. As a result of the heating, the comparative examples 1 and 1 both began to soften from 100 to 140 ° C and rapidly and completely between 150 and 170 ° C. It was confirmed that the liquefaction was observed, and Comparative Example 1 and Example 1 both exhibited the characteristics of the low melting point polyester.

Comparative example  2

Modified poly with improved dyeability by performing the same as in Comparative Example 1 except for adding the modifiers shown in Table 5, and the addition of the subsidiary materials shown in Table 6 on the basis of 1 ton polyester in the production of polyester Ester was prepared.

division Mole ratio Weight portion Input (kg) DMS 1.5 2 22 Polyethylene Glycol-1000 0.014 0.82 9

division The input Heat stabilizer H ₃ PO ₄ 150ppm Polycondensation Reaction Catalyst Sb ₂ O ₃ 300ppm Complement Co (CH ₃ CO ₂ ) ₂ 3000 ppm * Co (CH ₃ CO ₂ ) ₂ = cobalt acetate

As a physical property and color test of the low-melting polyester obtained according to the above, the color of the polyester chip was measured by the method of ASTM E398-90 and E805-93 and the values of L * and b *, melting point (Tm) and The content of diethylene glycol (DEG) as a by-product and the like were measured by a conventional method, and the results are shown in Table 7 below.

Example  2

As in Example 1, except that the modifiers shown in Table 5 of Comparative Example 2 and the subsidiary materials shown in Table 6 were added to the bis-2-hydroxyethyl terephthalate (BHET) as a modifier. Was performed.

division Hue L Hue b DEG Tm
(℃) Comparative Example 2 71.5 4.9 3 241.0 Example 2 61.4 11.2 4.5 231.4 * The DEG item means the content of diethylene glycol produced as a reaction by-product.
* The content of DEG is a weight percent based on the total weight of PET.

As shown in Table 7, the polyester having improved dyeability obtained by the method of preparing a modified polyester using waste polyester according to the present invention has a significant degree compared with a new polyester (Comparative Example 2). There was no significant difference.

It can be seen that the physical properties of the recycled polyester chip produced by the waste polyester chip manufacturing method is not significantly different from the example chip.

Therefore, in the production of regenerated polyester by depolymerization after ordinary depolymerization of polyethylene glycol, the regenerated polyester is remarkably improved in terms of physical properties by appropriate addition of modifiers in the polycondensation step, that is, according to the type and amount of modifier used. It was confirmed that the production of modified polyesters having low melting point characteristics or improved dyeability and the like could be reproduced with the same or similar quality as new materials.

The present invention can be used in the industry of producing and processing polyester, and can be used in the textile industry and the like using such polyester.

Claims (4)

In the manufacturing method of the polyester which depolymerizes waste polyester with bis-2-hydroxyethyl terephthalate (BHET), and then polycondenses the said bis-2-hydroxyethyl terephthalate to produce polyester,
(1) mixing the waste polyester with ethylene glycol (EG; ethylene glycol) as a catalyst and solvent to obtain a first mixture;
(2) a melting step of melting the waste polyester in the first mixture;
(3) depolymerization of the molten first mixture to produce bis-2-hydroxyethyl terephthalate (BHET); And
(4) a polycondensation step of mixing the bis-2-hydroxyethyl terephthalate in an amount of 1 to 25 parts by weight based on the total polyester weight (100 parts by weight) and polycondensing;
Characterized by made, including;
The modifier is polyethylene glycol (PEG) and dimethyl-5-sulfoisophthalate sodium salt (DMS) or polyethylene glycol (PEG) and isophthalic acid (IPA) method for producing a modified polyester using a waste polyester, characterized in that. delete The method of claim 1,
The polycondensation step using the waste polyester, characterized in that the bis-2-hydroxyethyl terephthalate is heated to a temperature range of 245 to 290 ℃ for 60 to 240 minutes while stirring at 30 to 90 rpm in a vacuum state Process for the preparation of modified polyesters. delete