Recycled thermoplastic polyester elastomer and method for manufacturing the same

Abstract

To provide: a recycled thermoplastic elastomer having excellent color tone and good physical properties; and a method for manufacturing the recycled thermoplastic elastomer.SOLUTION: The present invention pertains to a method for obtaining a recycled thermoplastic elastomer. The method includes: obtaining recycled polyester in one stage rection of alcohol decomposition and ester exchange by using a titanium compound catalyst in which polyol is coordinated; followed by reaction with polyol polymer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a recycled thermoplastic polyester elastomer having excellent hue and good physical properties and a method for producing the same.

Background Art

[0002] Recycled thermoplastic elastomer (rTPEE) is produced by reacting recycled polyester with polyol. Compared with polyester formed from monomers as reaction raw materials, when recycled polyester is used as the raw material, its performance deteriorates due to the technical limitations of recycling. The recovered products can only be used in low-end fields and cannot be recycled many times.

[0003] Currently, there are two methods for recycling polyethylene terephthalate (hereinafter referred to as "PET"): physical recycling and chemical recycling. The physical recycling method mainly involves directly mixing and granulating waste polyester and its products, and slicing and using the recycled resin. However, due to the large quality variation of the recycled resin slices, generally only conventional short fiber products can be manufactured, and the needs of high-end products cannot be met. Chemical methods include hydrolysis, methanol alcoholysis, ethylene glycol alcoholysis, 1,4-butanediol alcoholysis, microwave method, etc. However, due to the high recycling cost and technical requirements, recycled waste ester is not generally used in the production of recycled thermoplastic elastomer.

[0004] Chinese Patent Publication No. 106113319A discloses a method of obtaining recycled polyester by alcoholysis of processed polyester waste with ethylene glycol, followed by several steps of esterification and polycondensation, and then filtration. US Patent Publication No. 20070225474A1 discloses a method of depolymerizing polyethylene terephthalate (PET) into purified terephthalic acid (PTA) by using ethylene glycol and methanol. The method of using PET as a monomer raw material is difficult to commercialize because the process is complex and consumes a large amount of organic solvents and energy. European Patent No. 1437377B1 discloses a method of depolymerizing PET into bis-2-hydroxybutyl terephthalate (BHBT), an intermediate, at a high temperature of 200-260 °C by using 1,4-butanediol (BDO), and then polymerizing it into recycled thermoplastic elastomer (rTPEE) by adding a polyol polymer raw material. Compared with the conventional method of depolymerizing PET into PTA monomers and then using them, it is more energy-saving, but at least a two-step process including depolymerization and esterification is required, so the process is complex.

[0005] The production of recycled thermoplastic elastomers disclosed in the prior art all requires a transesterification reaction (i.e., a two-tank reaction) before polymerization after depolymerizing PET, as described in U.S. Patent No. 7,795,320. However, this production method is carried out in two steps and is not efficient and economical. Chinese Patent Publication No. 102675113A discloses that in order to obtain a good depolymerization effect, zinc acetate, a common depolymerization catalyst, is added to recycled polyester at 0.5 to 1.5% by weight. However, as described in Chinese Patent Publication No. 101531773A and Patent No. 107652423B, due to the large amount of this catalyst added, zinc ions remain in the system, the side reactions during polymerization are significant, the growth of the polymer molecular chain is restricted, and the quality of recycled polyester deteriorates. U.S. Patent Publication No. 20110178265A1 discloses that although the titanium catalyst used in the depolymerization step is in a small amount, due to the intense side reactions during the transesterification polymerization reaction, the ester particle products are prone to yellowing. On the other hand, Chinese Patent Publication No. 102164985A discloses that since the catalyst in the esterification reaction is generally unstable when exposed to water, when using a mannitol-modified titanium catalyst in the esterification polymerization reaction, yellowing can be reduced, but its application is still limited to the esterification reaction.

[0006] The process of alcoholysis of recycled polyester and esterification of polyol needs to be divided into two steps. The energy loss of reactor exchange is very large, and the characteristics required for the catalysts in the two types of reactions are not the same, so catalyst residues occur, and the yellowing degree and physical properties of the final product tend not to meet the requirements. Therefore, there is still a need for a simple method to produce recycled plastic elastomers by applying the catalysts of the two reaction systems simultaneously.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention provides a method for producing recycled thermoplastic elastomers using a dual catalyst system for depolymerization and transesterification, and a thermoplastic elastomer produced using the catalyst. This can directly reduce the energy loss when replacing the reaction vessel. In addition, since there are few side reactions of the catalyst and there is no need to remove the catalyst, it can be directly completed in one step. Furthermore, by using this catalyst, recycled thermoplastic elastomers having better hue and physical properties can be produced.

Means for Solving the Problems

[0008] One embodiment according to the present invention is (a) Using a titanium compound catalyst coordinated with a first polyol, performing alcoholysis of a first polyester and transesterification of a second polyol in a one-step reaction; (b) Recovering the second polyester obtained from the one-step reaction of alcoholysis and transesterification; A method for producing a recycled thermoplastic elastomer is provided, including the above steps.

[0009] The method for producing a recycled thermoplastic elastomer according to the present invention further includes (c) obtaining a recycled thermoplastic elastomer by adding and reacting about 20% to about 80% by weight of a polyol polymer.

Effects of the Invention

[0010] According to the present invention, a recycled thermoplastic elastomer having excellent hue and good physical properties and a method for producing the same can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0012] From the following detailed description of the preferred embodiments of the present invention, the features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings.

[0013] Hereinafter, each embodiment and other aspects according to the present disclosure will be described in detail. It should be understood that the invention according to the present disclosure can be embodied in various aspects and is not limited to the described embodiments. The embodiments according to the present disclosure are for making the content of the present disclosure sufficient and complete so that those skilled in the art can understand and implement the present disclosure. The present invention is intended to include alternatives, modifications, and equivalents within the spirit and scope of the embodiments described in the appended claims.

[0014] Numerical values such as concentrations or concentration ranges described in the present disclosure should be understood to be modified by the term "about" in all cases. The term "about" means within the allowable error range of a specific value determined by those skilled in the art, and it will depend in part on the limitations of the measurement system, i.e., how the value is measured or determined. In the context of a specific test, result, or example, unless otherwise specifically stated explicitly elsewhere in the example or specification, the term "about" means either within one standard deviation or within a maximum of 5%, whichever is greater, according to the convention in the technical field of the present disclosure.

[0015] Embodiments described by terms such as "one embodiment", "some embodiments", etc. may include specific features, structures, aspects, or characteristics, but not all embodiments necessarily include such specific features, structures, aspects, or characteristics. Furthermore, such expressions do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, aspect, or characteristic is described in relation to an embodiment, in this disclosure, whether explicitly described or not, it is within the knowledge of those skilled in the art, and thus, such a feature, structure, aspect, or characteristic is considered to be realizable in relation to other embodiments.

[0016] All technical and scientific terms mentioned in the specification and claims are, unless otherwise defined, definitions known to those skilled in the art. Singular terms such as "one", "said", or their similar terms refer to two or more objects unless otherwise explained. The terms "or", "and", and "with" used in this disclosure refer to "or / and" unless otherwise explained. Also, the terms "comprising" and "containing" are non-restrictive open connectives. Additionally, the above definitions are only for explaining the definitions of the terms and should not be construed as restrictions on the subject. Unless otherwise explained, all materials used in this disclosure are commercially available and easily obtainable.

[0017] As shown in FIG. 1, the present invention obtains a recycled thermoplastic elastomer by performing alcoholysis of a recycled polyester and transesterification with a polyol in a one-step reaction using a special coordination-modified titanium catalyst. The method for producing a recycled thermoplastic elastomer mainly includes: (a) a step of performing alcoholysis of a first polyester and transesterification with a second polyol in a one-step reaction using a titanium compound catalyst coordinated with a first polyol; (b) a step of recovering the second polyester obtained from the one-step reaction of alcoholysis and transesterification; and (c) a step of obtaining a recycled thermoplastic elastomer by adding and reacting about 20% by weight to about 80% by weight of a polyol polymer.

[0018] Examples of the polyester according to the present invention include, but are not limited to, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polycyclohexylene dimethylene terephthalate, polyethylene-2,6'-naphthalate, polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate, etc. All polyesters that can be depolymerized using the catalyst system of the present disclosure are within the scope of the present invention.

[0019] The present invention uses a self-made titanium compound catalyst coordinated and modified by a polyol to depolymerize a polyester, esterify it, and further selectively react with an alkali to improve stability in water, thereby obtaining a recycled thermoplastic elastomer having an excellent hue b* value, a melting point close to that of TPEE directly produced from PTA monomer as a raw material, and no extra components remaining in the ester particles.

[0020] The titanium compound catalyst coordinated and modified by the polyol according to the present invention refers to a dark-colored polymer product in which a polyol is used for coordination to protect titanium atoms, and a titanium dioxide polymer is generated by the reaction of by-products with water during the esterification reaction, thereby avoiding catalyst deactivation and delay of the esterification reaction.

[0021] The titanium compound catalyst coordinated and modified by the polyol according to the present invention is produced by reacting the molar ratio of the titanium compound to the polyol to be about 1:1 to about 1:3, and further selectively reacting the molar ratio of the titanium atom to the alkali to be about 1:1 to about 100:1 in order to improve the stability in water. In one specific example, as the titanium compound, tetramethoxytitanium (TMT), tetraethoxytitanium (TET), tetraisopropoxytitanium (TPT), tetrabutoxytitanium (TBT), etc. may be used, and tetramethoxytitanium or tetraisopropoxytitanium is preferred. As the first polyol, xylitol, sorbitol, maltitol, erythritol, mannitol, etc. may be used, and mannitol is preferred. Further, as the alkali used, an amine compound or an alkali metal compound, specifically, lithium hydroxide, sodium hydroxide, amine hydroxide, tetrabutylammonium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate, amine, triethylamine, etc. may be used, and lithium hydroxide or sodium hydroxide is preferred. The catalyst produced in the present invention has high polymerization activity, and the recycled thermoplastic elastomer obtained by the method using this catalyst has a good hue.

[0022] Through the following non-limiting examples, a method for producing a titanium compound catalyst modified by a polyol, and a method for producing a recycled thermoplastic elastomer by performing alcohol decomposition, depolymerization, esterification, and reaction with polyol 1 of recycled waste ester in one step using the catalyst will be described in detail.

[0023] <Manufacture of Catalyst> (Examples 1-5: Production of Titanium Catalyst Coordinated and Modified by Mannitol) The production of the titanium catalyst in Example 1 was carried out by putting 110 kg of 1,4-butanediol and 3 kg of mannitol into a reaction vessel, heating and reacting them at 80 °C for 30 minutes, then cooling the mixture to 45 °C, reacting for 6 hours, adding 4.5 kg of titanium isopropoxide, and reacting for 1 hour to obtain a titanium catalyst coordinated and modified with mannitol having a titanium content of 0.6% by weight. In Examples 2 to 5, the addition amount of the titanium catalyst coordinated and modified with mannitol was adjusted. As shown in Table 1 below, mannitol coordination-modified titanium catalysts (TC1 to 5) with different concentrations used in the examples of the one-step reaction of alcohol decomposition and esterification were obtained.

[0024] [Table 1] TIFF2025106777000002.tif5899

[0025] (Comparative Examples 1-4) As shown in Table 2 below, in Comparative Examples 1 to 4, depolymerization catalysts with different concentrations (i.e., titanium butoxide and zinc acetate) were used.

[0026] [Table 2] TIFF2025106777000003.tif50116

[0027] (Production of Thermoplastic Elastomer: One-step Reaction of Alcohol Decomposition and Ester Exchange) (Standard Example) 18 kg of terephthalic acid, 8.5 kg of 1,4 - butanediol, 11 kg of polytetrahydrofuran ether (molecular weight 1800 g / mol), 16 kg of polyethylene glycol (molecular weight 2000 g / mol), 0.024 mmol of titanium butoxide as a catalyst are put into an alcoholysis - transesterification reaction tank, and reacted at a reaction temperature of 220°C, a reaction pressure of 1 atm, and a reaction time of 6 hours. The product after the completion of transesterification is transferred to a polymerization reaction tank, 90 g of Irganox® 1010 as an antioxidant and 34 g of titanium butoxide are added, the temperature is raised to 245°C, the pressure is reduced to less than 1 torr, and the reaction is carried out for 3 - 4 hours. After reaching the set value of mechanical torque, the polymerization reaction tank is depressurized to normal pressure, the discharge part is opened, the ester strip is cooled by a water channel, and then cut into pellets using a pelletizer to obtain a recycled thermoplastic elastomer.

[0028] (Example 1) 18 kg of recycled polyethylene terephthalate, 8.5 kg of 1,4 - butanediol, 11 kg of polytetrahydrofuran ether (molecular weight 1800 g / mol), 16 kg of polyethylene glycol (molecular weight 2000 g / mol), a titanium catalyst coordinated and modified with mannitol (corresponding to the catalyst manufactured in Example 1 above and its concentration) are put into an alcoholysis - transesterification reaction tank, and reacted at a reaction temperature of 220°C, a reaction pressure of 1 atm, and a reaction time of 6 hours. The product after the completion of transesterification is transferred to a polymerization reaction tank, 90 g of Irganox® 1010 as an antioxidant and 34 g of titanium butoxide are added, the temperature is raised to 245°C, the pressure is reduced to less than 1 torr, and the reaction is carried out for 3 - 4 hours. After reaching the set value of mechanical torque, the polymerization reaction tank is depressurized to normal pressure, the discharge part is opened, the ester strip is cooled by a water channel, and then cut into pellets using a pelletizer to obtain a recycled thermoplastic elastomer having the physical properties shown in Table 3 below

[0029] (Examples 2 - 5) Similar to Example 1, a recycled thermoplastic elastomer having the physical properties shown in Table 3 below was obtained under the same reaction conditions, except that only the concentration of the titanium catalyst coordinated with mannitol (shown in Table 1) was added.

[0030] (Comparative Examples 1-4) Similar to Example 1, a recycled thermoplastic elastomer having the physical properties shown in Table 3 below was obtained under the same reaction conditions, except that the catalyst to be added and its addition amount (shown in Table 2) were changed.

[0031] (Physical properties of the thermoplastic elastomer) The method for measuring the physical properties of the thermoplastic elastomer standard product (hereinafter also referred to as the TPEE standard product) and the recycled thermoplastic elastomer will be described below.

[0032] (Intrinsic viscosity) According to the measurement method ASTM D-2857, a small amount of the sample is completely dissolved in tetrachloromethane, the flow rate of the solution is measured, and the intrinsic viscosity (unit: dl / g) of the object to be measured is determined.

[0033] (Hue) According to the measurement method ASTM D2244, the hue is determined using the L*a*b* color model established by the CIE as the color measurement standard. The L*a*b* color model consists of three elements. L* indicates brightness, L* = 0 indicates black, and L* = 100 indicates white. a* indicates the position between red and green, showing green when a* is a negative value and red when a* is a positive value. b* indicates the position between yellow and blue, showing blue when b* is a negative value and yellow when b* is a positive value. Therefore, in Table 2, the hue b* of the object to be measured is measured with a colorimeter and used as an index for reducing the degree of yellowing.

[0034] (Melting point) The melting point of the object to be measured is determined by differential scanning calorimetry (DSC) according to the measurement method ASTM E-794. The basic principle is that when the sample undergoes a phase change, glass transition, or chemical reaction, it absorbs and releases heat. Therefore, the compensator can detect how to increase or decrease the heat flow to keep the temperatures of the sample and the reference material constant. Thus, in Table 3 below, the melting point of the object to be measured is determined using a differential scanning calorimeter and used as an index for comparing with the physical properties of the TPEE standard product.

[0035] Table 3 shows the physical properties of the thermoplastic elastomers of Examples 1 to 5, Comparative Examples 1 to 4, and Standard Example measured by the above method.

[0036] [Table 3] TIFF2025106777000004.tif97163

[0037] The recycled thermoplastic elastomer (rTPEE) obtained in the above Examples and Comparative Examples, compared with the TPEE standard product of the Standard Example, shows that the titanium catalyst coordinated with the polyol used in the present invention can be carried out in a one-step reaction of alcohol decomposition and transesterification, and it is possible to produce a recycled thermoplastic elastomer of higher quality than the conventional catalyst. The obtained recycled thermoplastic elastomer (rTPEE) has an intrinsic viscosity, hue, and melting point all close to those of the TPEE standard product, indicating that there are no excessive other components generated by side reactions in the ester particles.

[0038] Figure 2 is a diagram showing the results of differential scanning calorimetry (DSC) of rTPEE produced in the Examples according to the present invention, rTPEE produced with other alcohol decomposition and depolymerization catalyst systems, and the TPEE standard product. As shown in Figure 2, compared with the Comparative Examples, the Examples of the present invention have an rTPEE characteristic pattern closer to that of the TPEE standard product, with fewer impurities, higher purity, and physical properties closer to those of the TPEE standard product.

[0039] The intrinsic viscosity of the recycled thermoplastic elastomer mainly affects the flow characteristics during use such as spinning, film coating, injection molding, etc. The intrinsic viscosity is preferably 1.83 - 1.9 dl / g and optimally 1.85 - 1.9 dl / g from the influence of use. The hue mainly affects the appearance during use, and yellowing also causes property deterioration, so the hue b* is preferably +7 to +9.2 and optimally +7 to +8.5. The melting point mainly affects the control of physical properties such as processing temperature and heat resistance, and the melting point is preferably 166 - 171 °C and optimally 168 - 171 °C.

[0040] The present invention uses a special coordination-modified titanium catalyst to perform the alcoholysis of recycled polyester and the transesterification with a polyol in a one-step reaction to obtain a recycled thermoplastic elastomer, so that any of the intrinsic viscosity, hue b*, and melting point can be controlled within an appropriate range, and the quality requirements of the recycled thermoplastic elastomer can be met. Therefore, the present invention provides a method for manufacturing an economical and high-quality recycled thermoplastic elastomer.

[0041] For the purpose of interpretation, specific terms are used in the above description to enable a complete understanding of the described examples. However, those skilled in the art should understand that the above embodiments can be implemented without many specific details. Therefore, the above description of the specific embodiments of the present disclosure is presented for illustrative and explanatory purposes. This is not intended to be exhaustive or to limit the described embodiments to a specific form. Those skilled in the art should understand that various modifications or changes can be made from the above description.

[0042] The summary and abstract of the invention can show one or more, but not all, of the exemplary embodiments of the present disclosure contemplated. Therefore, it is not intended to limit the present disclosure and the appended claims in any way.

[0043] The above description of the specific examples fully reveals the general essence of the present disclosure, and others can easily modify and / or substitute such examples or specific examples for various applications by applying the knowledge in the technical field without the need for excessive experiments and without departing from the spirit of the present disclosure. Therefore, based on the description or teaching of the present disclosure, such modifications and substitutions are intended to be within the meaning and scope of equivalents of the described examples. Therefore, the terms or expressions in the present disclosure are for illustrative purposes rather than for limitation, and should be understood to be interpreted by those skilled in the art from the description or teaching of the present disclosure. The scope and range of the present disclosure should not be limited by the above exemplary embodiments, but should be defined based on either the appended claims or their equivalent scope.

Claims

1. (a) Using a titanium compound catalyst coordinated with a first polyol, performing alcoholysis of a first polyester and transesterification of a second polyol in a one-step reaction; (b) Recovering a second polyester obtained from the one-step reaction of the alcoholysis and the transesterification; A method for producing a recycled thermoplastic elastomer, comprising the steps of.

2. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the coordination ratio of the first polyol to the titanium compound catalyst is about 1:1 to about 3:

1.

3. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the first polyol is selected from the group consisting of xylitol, sorbitol, maltitol, erythritol, and mannitol.

4. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the titanium compound catalyst coordinated with the first polyol is produced by adding an alkali metal salt and reacting.

5. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the titanium compound catalyst coordinated with the first polyol is produced through a reaction in an ethanol / water system.

6. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the titanium compound catalyst coordinated with the first polyol is produced through a reaction at a reaction temperature of about 0°C to about 100°C.

7. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the titanium compound catalyst coordinated with the first polyol is produced with a reaction time of about 2 hours to about 8 hours.

8. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the addition amount of the titanium compound catalyst coordinated with the first polyol is about 0.01 to about 1 mmol.

9. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the first polyester is selected from the group consisting of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polycyclohexylene dimethylene terephthalate (PCT), polyethylene-2,6'-naphthalate (PEN), and polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate.

10. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the second polyol is selected from the group consisting of ethylene glycol, propylene glycol, and butylene glycol.

11. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the second polyester is selected from the group consisting of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene terephthalate (PBT).

12. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the reaction temperature in step (a) is about 190°C to about 240°C.

13. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the reaction pressure in step (a) is about 1 atm to about 2.5 atm.

14. The method for producing a recycled thermoplastic elastomer according to claim 1, wherein the reaction time in step (a) is about 2 hours to about 8 hours.

15. The method for producing a recycled thermoplastic elastomer according to any one of claims 1, 12 to 14, further comprising the step of obtaining the recycled thermoplastic elastomer by adding and reacting about 20% by weight to about 80% by weight of a polyol polymer.

16. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein the number of carbon atoms of the polyol polymer in step (c) is 2 to 7.

17. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein the molecular weight of the polyol polymer in step (c) is about 200 g / mol to about 10,000 g / mol.

18. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein the reaction temperature in step (c) is about 220°C to about 280°C.

19. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein the reaction pressure in step (c) is less than about 1 atm.

20. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein the reaction time in step (c) is about 2 hours to about 6 hours.

21. The method for producing a recycled thermoplastic elastomer according to claim 15, wherein step (c) further comprises adding about 0.5% by weight to about 5% by weight of an additive.

22. The production method of the recycled thermoplastic elastomer according to claim 21, wherein the additive is selected from the group consisting of an antioxidant, an ultraviolet absorber, and a crosslinking agent.

23. A recycled thermoplastic elastomer produced by the production method of the recycled thermoplastic elastomer according to any one of claims 1 to 22.

Images