Preparation method and application of ultraviolet aging resistant polyether ester elastomer

Abstract

The invention belongs to the technical field of high polymer materials, and relates to a preparation method and application of an ultraviolet aging resistant polyether ester elastomer, the preparation method comprises the following steps: firstly, carrying out esterification reaction or ester exchange reaction on 1, 4-cyclohexanedimethanol and an oxalic acid compound to obtain hydroxyl-terminated oxalate; mixing the hydroxyl-terminated oxalate with an aromatic dibasic acid compound, aliphatic dihydric alcohol, polyether glycol, a catalyst and an antioxidant, and sequentially performing esterification reaction, pre-polycondensation reaction and final polycondensation reaction to obtain the ultraviolet aging resistant polyether ester elastomer. Wherein the oxalic acid compound is oxalic acid or ester of oxalic acid; the aromatic dibasic acid compound is aromatic dibasic acid or ester of the aromatic dibasic acid. Compared with the prior art, the preparation method disclosed by the invention has the characteristics of simple preparation process and good ultraviolet aging resistance, a sample is placed in an ultraviolet aging test box to be irradiated for 30 days, the optimal tensile strength reduction percentage is 38.9% which is lower than 48.5% of the tensile strength before hydroxyl-terminated oxalate copolymerization, and the ultraviolet aging resistance is obviously improved.

Description

A method for preparing and applying a UV-resistant polyether ester elastomer Technical Field

[0001] This invention belongs to the field of polymer materials technology and relates to a method for preparing and applying a UV-resistant polyether ester elastomer. Background Technology

[0002] Thermoplastic polyether ester elastomer (TPEE) is a high-performance engineering plastic that combines the elasticity of rubber with the processability of plastics. TPEE is a multi-block linear polymer with a chemical structure consisting of crystalline saturated polyester as hard segments and amorphous polyether with a low glass transition temperature as soft segments. The hard segments provide the material's strength and structure, while the soft segments provide flexibility and elasticity. This alternating arrangement of multi-block segments gives TPEE the properties of both rubber and thermoplastics; it exhibits rubber-like characteristics at room temperature while being plasticizable at high temperatures.

[0003] TPEE possesses mechanical and physicochemical properties between traditional rubber and plastics, making it an important engineering-grade elastomer material. Its excellent mechanical properties, high elasticity, heat resistance, and chemical resistance, among other superior characteristics, lead to its widespread application in the automotive industry, industrial applications, packaging materials, medical equipment, and consumer goods. In the automotive industry, it is used to manufacture interior and exterior automotive components such as sealing strips, dust covers, and air ducts. Industrial applications include wires and cables, hydraulic hoses, and industrial belts.

[0004] In outdoor applications, TPEE (Polyester Polyester Effective Materials) inevitably encounters ultraviolet (UV) radiation. UV radiation accounts for 6% of total solar radiation, with wavelengths ranging from 200-400 nm. Research has found that 310 nm UV radiation is the primary factor causing breakage of the hard segments in the polyester molecular chain of TPEE. Currently, there are four main methods to improve the UV resistance of TPEE: 1. Adding UV absorbers: Introducing UV absorbers into the polyester to protect the polyester molecular chain from damage. This is the most common method used industrially to improve the UV resistance of polyester. 2. Adding nano-inorganic fillers: Introducing nano-inorganic fillers with UV-shielding properties, such as nano-zinc oxide and nano-titanium dioxide, into the polyester matrix to improve its UV resistance. 3. Modification: Selecting polymers, intermediates, and monomers with excellent UV resistance and improving the UV resistance of TPEE through physical blending or chemical modification. 4. Synthesis: Starting from the polyester molecular structure, selecting monomers with inherent UV resistance during synthesis. Of the four methods mentioned above, the synthesis method does not require further chemical or physical modification, nor does it require the addition of fillers or UV absorbers, thus fundamentally solving the problem of UV aging.

[0005] Chinese patent CN114805771A discloses an amorphous copolyester with a high glass transition temperature, its preparation method, and its applications. The preparation method involves transesterifying dimethyl oxalate and 4,4'-dihydroxydicyclohexane at a molar ratio of 2-5:1 to obtain an end-group modified monomer. The end-group modified monomer, a diacid, a diol, and a catalyst are then mixed and polymerized to obtain the amorphous copolyester with a high glass transition temperature. The resulting copolyester exhibits high glass transition temperature and high molecular weight. The application involves melt-extruding the amorphous copolyester in a twin-screw extruder, casting and cooling the melt to obtain polyester sheets, and then preheating the polyester sheets in a biaxial stretching machine before biaxial stretching to produce polyester films or sheets. This invention offers a flexible preparation method, and the product exhibits good heat resistance, high transparency, and processability, making it highly promising for applications in film packaging and bottling.

[0006] Chinese patent CN103665787A discloses a method for preparing a thermoplastic polyester elastomer resistant to high-temperature yellowing. This method improves the UV resistance of the thermoplastic polyester elastomer by using a compound of phenolic antioxidants, amine antioxidants, and phosphite compounds. This invention belongs to the modification method, and its composition is as follows: 100 parts thermoplastic polyester, 0-0.4 parts phenolic antioxidants, 0-0.4 parts amine antioxidants, and 0.05-0.4 parts phosphite compounds. Chinese patent CN103709612A discloses a method for preparing a UV-resistant thermoplastic polyester elastomer, whose components are: 100 parts thermoplastic polyester, 0-0.4 parts phenolic antioxidants, 0-0.4 parts amine antioxidants, 0.1-0.4 parts sulfur compounds, and 0.1-0.3 parts hindered amine UV stabilizers. This invention utilizes the synergistic effect of antioxidants and stabilizers, using sulfur compounds as auxiliary antioxidants to effectively improve the material's resistance to yellowing, thereby achieving heat resistance, UV resistance, and yellowing resistance. However, the above method may affect the material's transparency, and the various additives may migrate to the material surface over time, causing yellowing, fading, cracking, and even loss of physical properties, making it unusable for long-term effective use.

[0007] Therefore, it is necessary to develop a method for thermoplastic polyether ester elastomer with good UV aging resistance based on molecular structure, so as to fundamentally solve the problem. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing and applying a UV-resistant polyether ester elastomer. This invention first prepares a terminal hydroxyl oxalate ester using oxalic acid or its esterified form and 1,4-cyclohexanediethanol. Then, the terminal hydroxyl oxalate ester is polymerized with aromatic diacids or their esterified forms, aliphatic diols, polyether diols, and other raw materials to obtain a thermoplastic polyether ester elastomer with good UV resistance. This method features a simple preparation process and excellent UV resistance. After irradiating the sample in a UV aging test chamber for 30 days, the optimal percentage reduction in tensile strength is 38.9%, lower than the 48.5% before copolymerization with the terminal hydroxyl oxalate ester, indicating a significant improvement in UV resistance.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] The first aspect of the present invention provides a method for preparing a UV-resistant polyether ester elastomer, comprising the following steps:

[0011] S1: 1,4-cyclohexanediethanol is esterified or transesterified with oxalic acid compounds to obtain terminal hydroxy oxalate.

[0012] S2: Hydroxyl oxalate is mixed with aromatic dicarboxylic acid compounds, aliphatic diols, polyether diols, catalysts, and antioxidants, and then subjected to esterification, pre-condensation, and final condensation reactions in sequence to obtain UV-resistant polyether ester elastomers.

[0013] Wherein, the oxalic acid compounds are oxalic acid or esters of oxalic acid; the aromatic dicarboxylic acid compounds are aromatic dicarboxylic acids or esters of aromatic dicarboxylic acids.

[0014] Furthermore, in step S1, the esterification reaction or transesterification reaction is carried out at a temperature of 120–160°C, the reaction atmosphere is nitrogen or an inert gas, and the catalyst used is zinc acetate.

[0015] As a preferred technical solution, the esterification or transesterification reaction is carried out in a reaction vessel. When the top temperature reaches 64°C, the byproduct methanol is collected. The reaction ends when the top temperature drops below 50°C and the amount of byproduct reaches more than 95% of the theoretical mass. After cooling to room temperature, the terminal hydroxyoxalate obtained from the reaction is collected for later use.

[0016] Further, in step S1, the molar ratio of 1,4-cyclohexanediethanol to oxalic acid compound is (2.0-2.5):1; preferably (2.0-2.2):1; more preferably (2.0-2.1):1.

[0017] Further, in step S1, the amount of catalyst used is 0.08 to 1.0% of the total mass of 1,4-cyclohexanediethanol and oxalic acid compounds; preferably 0.1% to 0.5%.

[0018] Further, in step S1, the oxalic acid compound is selected from one or more of oxalic acid, dicarboxylic acid oxalate, diethyl oxalate, dibutyl oxalate, diphenyl oxalate, or dibenzyl oxalate, and any combination thereof.

[0019] Further, in step S2, the aromatic dicarboxylic acid compound is selected from one or more of the following: terephthalic acid or its esterified form, isophthalic acid or its esterified form, phthalic acid or its esterified form, phthalic anhydride or its esterified form, 1,4-naphthalenedicarboxylic acid or its esterified form, 2,7-naphthalenedicarboxylic acid or its esterified form, 2,6-naphthalenedicarboxylic acid or its esterified form, and 4,4'-biphenyldicarboxylic acid or its esterified form.

[0020] Further, in step S2, the aliphatic diol is selected from one or more of the following: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, pentanediol, neopentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, 1,4-cyclohexanediol, diethylene glycol, or 2,2,4-trimethyl-1,3-pentanediol.

[0021] Further, in step S2, the polyether diol is selected from one or a combination of two of polyethylene glycol and polytetramethylene ether diol.

[0022] Further, in step S2, the catalyst is selected from one or more of sodium acetate, zinc acetate, manganese acetate, antimony acetate, tetrabutyl titanate, tetraisopropyl titanate, dibutyltin oxide, dibutyltin dilaurate, stannous octoate, antimony glycolate, or antimony trioxide.

[0023] Further, in step S2, the antioxidant is selected from one or more of antioxidant 168, antioxidant 1010, antioxidant 1076, antioxidant 1098 and antioxidant 1330, or any combination thereof.

[0024] As a preferred technical solution, the number average molecular weight of the polyether diol is 500-2000.

[0025] Further, in step S2, the molar ratio of the terminal hydroxy oxalate to the aromatic dicarboxylic acid compound, the aliphatic diol, and the polyether diol is (0.4-3.1):2.7:(1.2-3.9):0.3.

[0026] As a preferred technical solution, the molar ratio of the aliphatic diol to the aromatic dicarboxylic acid compound is (1.2-2.0):1; more preferably (1.2-1.9):1.

[0027] Further, in step S2, the amount of the catalyst is 0.02-0.8% of the total mass of the terminal hydroxy oxalate, aromatic dicarboxylic acid compound, aliphatic diol, and polyether diol; preferably 0.05-0.5%.

[0028] Further, in step S2, the amount of the antioxidant is 0.08 to 1.0% of the total mass of the terminal hydroxy oxalate, aromatic dicarboxylic acid compound, aliphatic diol, and polyether diol; preferably 0.1 to 0.5%.

[0029] Furthermore, in step S2, the esterification reaction is carried out at a temperature of 200–220°C, and the reaction atmosphere is nitrogen or an inert gas.

[0030] As a preferred technical solution, the esterification reaction is terminated when the conversion rate is >95%.

[0031] Furthermore, in step S2, the pre-condensation reaction is carried out at a temperature of 240–250°C, a pressure of 0.8–1.2 kPa, and a time of 1–4 h.

[0032] Furthermore, in step S2, the final polycondensation reaction is carried out at a temperature of 240–245°C, a pressure of no more than 30 Pa, and a reaction time of 1–3 h.

[0033] As a preferred technical solution, the final polycondensation reaction is stopped when the polymer viscosity reaches 1.0 to 1.9 dl / g.

[0034] A second aspect of the present invention provides an application of a UV-resistant polyether ester elastomer, including using the UV-resistant polyether ester elastomer in automotive and industrial applications, such as sealing strips, dust covers, air ducts, wires and cables, and industrial belts.

[0035] Compared with the prior art, the present invention has the following characteristics:

[0036] 1) This invention improves the UV aging resistance of products by addressing their molecular structure. Since the terminal hydroxyl oxalate chain segment does not contain easily absorbed UV groups or structures (such as benzene rings, ketones, tertiary carbons, etc.), after oxalate is copolymerized with other raw materials, the oxalic acid structure reduces the content of benzene ring structures in the product chain segment to a certain extent. Simultaneously, the cyclohexane structure of 1,4-cyclohexanediethanol exhibits good UV resistance, thereby improving the product's UV aging resistance. Experiments show that the polyether ester elastomer material prepared by this invention, after being irradiated in a UV aging test chamber for 30 days, exhibits an optimal decrease in tensile strength of 38.9%, lower than the 48.5% before copolymerization with the terminal hydroxyl oxalate, demonstrating a significant improvement in UV aging resistance.

[0037] 2) The method provided by this invention has the characteristics of simple and readily available raw materials, simple operation, and controllable polymerization process, making it suitable for industrial scale-up and having good economic prospects. Attached Figure Description

[0038] Figure 1 shows the trend of tensile strength after UV aging over time. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0040] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0041] In the following embodiments, the preparation method of terminal hydroxyoxalate includes the following steps:

[0042] 1) Add 118.1 g (1 mol) of dimethyl oxalate and 295.6 g (2.05 mol) of 1,4-cyclohexanediethanol to a reaction vessel, then add 0.83 g of zinc acetate. After replacing the air in the vessel with N2, heat the mixture to 140±5℃ (this temperature range corresponds to a high reaction conversion rate and has no significant impact on the structure / performance of the final product, polyether ester elastomer; preferably, 140℃ is used as the reaction temperature) for the reaction.

[0043] 2) When the peak temperature reaches 64℃, the byproduct methanol is collected. The reaction ends when the peak temperature drops below 50℃ and the amount of byproduct reaches more than 95% of the theoretical mass.

[0044] 3) After cooling to room temperature, collect the terminal hydroxy oxalate obtained from the reaction for later use.

[0045] Example 1:

[0046] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0047] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 350.4g (3.888mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 148.0g (0.432mol) of terminal hydroxy oxalate (DMO-CHDM), 0.75g (0.06wt%) of tetrabutyl titanate (TBT), 1.12g (0.09wt%) of zinc acetate (Zn(OAc)2), 3.74g (0.3wt%) of antioxidant 1010, and 3.74g (0.3wt%) of antioxidant 168 were added to the reactor;

[0048] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. The reactor is stirred at 120 rpm and the temperature is gradually increased to 200-220°C (this temperature range corresponds to a high reaction conversion rate and has no significant impact on the structure / performance of the final product, polyether ester elastomer. Preferably, 210°C is used as the reaction temperature, and the same applies to the following examples). The reaction is carried out at atmospheric pressure for 3 hours. The mass of the by-product water is collected to calculate the conversion rate (actual mass of by-product / theoretical mass of by-product). The esterification reaction is ended when the conversion rate is >95%.

[0049] S3: Continue heating to 240℃ and control the reactor temperature below 250℃ (this temperature range corresponds to a high reaction conversion rate and has no significant impact on the final product, polyether ester elastomer; preferably, 245℃ is used as the reaction temperature, as in the following examples). Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours (this has no significant impact on the final product, polyether ester elastomer structure / performance; preferably, 2 hours is used as the reaction time, as in the following examples). Next, maintain the reactor temperature at 245–250℃ (this has no significant impact on the final product, polyether ester elastomer; preferably, 248℃ is used as the reaction temperature, as in the following examples), adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain UV-resistant polyether ester elastomer.

[0050] Example 2:

[0051] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0052] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 311.5g (3.456mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 295.9g (0.864mol) of terminal hydroxy oxalate (DMO-CHDM), 0.81g (0.06wt%) of tetrabutyl titanate (TBT), 1.22g (0.09wt%) of zinc acetate (Zn(OAc)2), 4.07g (0.3wt%) of antioxidant 1010, and 4.07g (0.3wt%) of antioxidant 168 were added to the reactor;

[0053] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0054] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0055] Example 3:

[0056] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0057] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 272.5g (3.024mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 443.88g (1.296mol) of terminal hydroxy oxalate (DMO-CHDM), 0.88g (0.06wt%) of tetraisopropyl titanate (TPT), 1.32g (0.09wt%) of zinc acetate (Zn(OAc)2), 4.39g (0.3wt%) of antioxidant 1010, and 4.39g (0.3wt%) of antioxidant 168 were added to the reactor;

[0058] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0059] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0060] Example 4:

[0061] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0062] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 233.6g (2.592mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 591.8g (1.728mol) of hydroxy-terminated oxalate (DMO-CHDM), 0.94g (0.06wt%) of tetrabutyl titanate (TBT), 1.42g (0.09wt%) of zinc acetate (Zn(OAc)2), 4.72g (0.3wt%) of antioxidant 1010, and 4.72g (0.3wt%) of antioxidant 168 were added to the reactor;

[0063] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0064] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0065] Example 5:

[0066] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0067] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 194.7g (2.16mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 739.8g (2.16mol) of terminal hydroxy oxalate (DMO-CHDM), 1.01g (0.06wt%) of tetrabutyl titanate (TBT), 1.51g (0.09wt%) of zinc acetate (Zn(OAc)2), 5.05g (0.3wt%) of antioxidant 1010, and 5.05g (0.3wt%) of antioxidant 168 were added to the reactor;

[0068] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0069] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0070] Example 6:

[0071] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0072] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 155.7g (1.728mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 887.8g (2.592mol) of hydroxy-terminated oxalate (DMO-CHDM), 1.08g (0.06wt%) of tetrabutyl titanate (TBT), 1.61g (0.09wt%) of zinc acetate (Zn(OAc)2), 5.38g (0.3wt%) of antioxidant 1010, and 5.38g (0.3wt%) of antioxidant 168 were added to the reactor;

[0073] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0074] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0075] Example 7:

[0076] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which includes the following steps:

[0077] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 116.8g (1.296mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 1035.7g (3.024mol) of terminal hydroxy oxalate (DMO-CHDM), 1.14g (0.06wt%) of tetrabutyl titanate (TBT), 1.71g (0.09wt%) of zinc acetate (Zn(OAc)2), 5.7g (0.3wt%) of antioxidant 1010, and 5.7g (0.3wt%) of antioxidant 168 were added to the reactor;

[0078] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0079] S3: Continue heating to 240℃ and control the vessel temperature below 250℃, adjusting the rotation speed to 50 rpm.

[0080] The pressure was slowly reduced to 1 kPa, and the reaction was carried out for 1–4 hours. Then, the reactor temperature was maintained at 245–250℃, the rotation speed was adjusted to 100 rpm, and the pressure was gradually reduced to below 30 Pa, and the reaction was carried out for 1–3 hours. Samples were taken for analysis. When the polymer viscosity reached 1.0–1.9 dl / g, stirring was stopped, the vacuum was removed, and the material was discharged under pressure to obtain the UV-resistant polyether ester elastomer.

[0081] Example 8:

[0082] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which differs from that of Example 5 only in that polytetrahydrofurandimethylethanol (PTMG-1000) is replaced with polytetrahydrofurandimethylethanol (PTMG-2000). Specifically, it includes the following steps:

[0083] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 194.7g (2.16mol) of 1,4-butanediol (BDO), 600g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-2000), 739.8g (2.16mol) of hydroxy-terminated oxalate (DMO-CHDM), 1.19g (0.06wt%) of tetrabutyl titanate (TBT), 1.78g (0.09wt%) of zinc acetate (Zn(OAc)2), 5.95g (0.3wt%) of antioxidant 1010, and 5.95g (0.3wt%) of antioxidant 168 were added to the reactor;

[0084] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0085] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0086] Example 9:

[0087] A UV-resistant thermoplastic polyether ester elastomer, the preparation method of which differs from that of Example 5 only in that terephthalic acid (PTA) is replaced with dimethyl terephthalate (DMT), specifically including the following steps:

[0088] S1: Dimethyl terephthalate (DMT) 524.3g (2.7mol), 1,4-butanediol (BDO) 194.7g (2.16mol), polytetrahydrofurandimethyl alcohol (PTMG-1000) 300g (0.3mol), hydroxy-terminated oxalate (DMO-CHDM) 739.8g (2.16mol), tetrabutyl titanate (TBT) 1.06g (0.06wt%), zinc acetate (Zn(OAc)2) 1.58g (0.09wt%), antioxidant 1010 5.28g (0.3wt%) and antioxidant 1685.28g (0.3wt%) were added to the reactor;

[0089] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0090] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0091] Comparative Example 1:

[0092] A thermoplastic polyether ester elastomer, the preparation method of which differs from that of Example 4 only in that: the terminal hydroxyl oxalate (DMO-CHDM) is removed and an equal amount of 1,4-butanediol (BDO) is added, specifically including the following steps:

[0093] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 389.3g (4.32mol) of 1,4-butanediol (BDO), 300g (0.3mol) of polytetrahydrofurandimethylethanol (PTMG-1000), 0.68g (0.06wt%) of tetrabutyl titanate (TBT), 1.02g (0.09wt%) of zinc acetate (Zn(OAc)2), 3.41g (0.3wt%) of antioxidant 1010, and 3.41g (0.3wt%) of antioxidant 168 were added to the reactor;

[0094] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0095] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0096] Comparative Example 2:

[0097] A thermoplastic polyether ester elastomer, the preparation method of which differs from that of Example 4 only in that: terephthalic acid (PTA) is replaced with dimethyl oxalate (DMO); and the terminal hydroxyl oxalate (DMO-CHDM) is removed and an equal amount of 1,4-butanediol (BDO) is added, specifically including the following steps:

[0098] S1: Dimethyl oxalate (DMO) 318.9g (2.7mol), 1,4-butanediol (BDO) 389.3g (4.32mol), polytetrahydrofurandimethyl alcohol (PTMG-1000) 300g (0.3mol), tetrabutyl titanate (TBT) 0.60g (0.06wt%), zinc acetate (Zn(OAc)2) 0.91g (0.09wt%), antioxidant 1010 3.02g (0.3wt%) and antioxidant 168 3.02g (0.3wt%) were added to the reactor;

[0099] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0100] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0101] Comparative Example 3:

[0102] A thermoplastic polyether ester elastomer, the preparation method of which differs from that of Example 4 only in that the hydroxyl-terminated oxalate ester (DMO-CHDM) is replaced with 1,4-cyclohexanediethanol (CHDM), specifically including the following steps:

[0103] S1: 448.6g (2.7mol) of terephthalic acid (PTA), 233.6g (2.592mol) of 1,4-butanediol (BDO), 249.2g (1.728mol) of 1,4-cyclohexanediethanol (CHDM), 300g (0.3mol) of polytetrahydrofurandiethanol (PTMG-1000), 0.74g (0.06wt%) of tetrabutyl titanate (TBT), 1.11g (0.09wt%) of zinc acetate (Zn(OAc)2), 3.69g (0.3wt%) of antioxidant 1010, and 3.69g (0.3wt%) of antioxidant 168 were added to the reactor;

[0104] S2: After the raw materials and catalysts are fed in, the air in the reactor is replaced with nitrogen three times. After the replacement is completed, the temperature is gradually increased until all the raw materials are melted. Stir at 120 rpm and gradually increase the temperature of the reactor to 200-220°C. React at atmospheric pressure for 3 hours. Collect the mass of the by-products and calculate the conversion rate. When the conversion rate is >95%, the esterification reaction is terminated.

[0105] S3: Continue heating to 240℃ and control the reactor temperature below 250℃. Adjust the rotation speed to 50 rpm, slowly reduce the pressure to 1 kPa, and react for 1–4 hours. Next, maintain the reactor temperature at 245–250℃, adjust the rotation speed to 100 rpm, gradually reduce the pressure to below 30 Pa, and react for 1–3 hours. Take samples for analysis. When the polymer viscosity reaches 1.0–1.9 dl / g, stop stirring, remove the vacuum, and pressurize the material to obtain the UV-resistant polyether ester elastomer.

[0106] The performance of the polyether ester elastomers in the examples and comparative examples was tested according to relevant standards:

[0107] IV (Intrinsic Viscosity): GB / T 14190-2008 Test Method for Fiber Grade Polyester Chips (PET).

[0108] Melt flow index: GB / T 3682.2-2018 Plastics Thermoplastics Determination of melt mass flow rate (MFR) and melt volumetric flow rate (MVR) Part 2: Test methods for materials sensitive to time-temperature history and / or humidity.

[0109] Molecular weight: Detected using a Waters 1515 gel permeation chromatograph with an Agilent PLgel 5μm MIXED-C column, hexafluoroisopropanol as the mobile phase, a flow rate of 1 mL / min, and polystyrene standard.

[0110] Mechanical properties: GB / T 1040.1-2018 Determination of tensile properties of plastics - Part 1: General rules; GB / T 1040.2-2022 Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics.

[0111] UV aging resistance: GB / T 16422.3-2014 Plastics Laboratory Light Source Exposure Test Method Part 3: Fluorescent UV Lamp. Place the sample in a UV aging test chamber and test the tensile strength after irradiation for 5, 10, 20 and 30 days respectively.

[0112] Table 1. Sample Information Summary

[0113]

[0114] Table 2. Comparison of samples before and after UV aging test

[0115]

[0116]

[0117] From Table 1, Table 2 and Figure 1, we can see that:

[0118] 1) The melt flow index of all examples was less than 20 g / 10 min, and the percentage decrease in tensile strength after 30 days was less than 47%.

[0119] 2) In Examples 1 to 7, when the amount of DMO-CHDM increased from 10% to 70% of the total diol molar amount, the percentage decrease in tensile strength after 30 days first decreased and then increased. When the amount was 40%, the percentage decrease after 30 days was only 38.9%. Therefore, the formulation in Example 4 is the optimal one.

[0120] 3) Example 9 is based on Example 5, but PTA is replaced with DMT. The indicators and performance of the two are not much different. Therefore, the formulation in this invention is applicable to both esterification and transesterification.

[0121] 4) Example 8 is based on Example 5, but PTMG-1000 is replaced with PTMG-2000. The initial tensile strength of Example 8 is comparable to that of Example 5, but it is significantly lower than that of Example 5 after 30 days. Therefore, a 1000 molecular weight polyether diol can produce a sample with higher strength and better UV aging resistance.

[0122] 5) Compared to Example 4, Comparative Examples 1-3 all removed terminal hydroxy oxalate, Comparative Example 2 used DMO instead of PTA, and Comparative Example 3 added an equimolar amount of CHDM. However, the percentage decrease in tensile strength after 30 days was significantly larger, ranging from 48.5% to 52.6%, far worse than the 38.9% in Example 4. Furthermore, based on Example 5, this invention also conducted experiments using an equimolar amount of DMO instead of PTA. The amount of CHDM was calculated based on the amount of DMO, consistent with the DMO / CHDM molar ratio used in the synthesis of terminal hydroxy oxalate (DMO-CHDM). These were used as comparative examples to examine their tensile properties, but the experimental results showed that the mechanical properties of the obtained materials were extremely poor and could not be properly characterized.

[0123] Analysis of the differences between the examples and comparative examples shows that only a polymerization process that simultaneously includes oxalic acid and cyclohexane structures, and that first prepares terminal hydroxy oxalate esters before reacting them with other raw materials, can achieve the best results.

[0124] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a UV-resistant polyether ester elastomer, characterized in that, The method includes the following steps: S1: 1,4-cyclohexanediethanol is subjected to esterification or transesterification with an oxalic acid compound to obtain a terminal hydroxyl oxalate; S2: The terminal hydroxyl oxalate is mixed with an aromatic dicarboxylic acid compound, an aliphatic diol, a polyether diol, a catalyst, and an antioxidant, and then subjected to esterification, pre-condensation, and final condensation reactions in sequence to obtain a UV-resistant polyether ester elastomer; wherein the oxalic acid compound is oxalic acid or an esterified form of oxalic acid; and the aromatic dicarboxylic acid compound is an aromatic dicarboxylic acid or an esterified form of aromatic dicarboxylic acid.

2. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S1, the esterification reaction or transesterification reaction is carried out at a temperature of 120-160°C, the reaction atmosphere is nitrogen or an inert gas, and the catalyst used is zinc acetate.

3. The method for preparing the UV-resistant polyether ester elastomer according to claim 2, characterized in that, In step S1, the molar ratio of 1,4-cyclohexanediethanol to oxalic acid compounds is (2.0-2.5):1, and the amount of catalyst used is 0.08-1.0% of the total mass of 1,4-cyclohexanediethanol and oxalic acid compounds.

4. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S1, the oxalic acid compound is selected from one or more of oxalic acid, dicarboxylic acid oxalate, diethyl oxalate, dibutyl oxalate, diphenyl oxalate, or dibenzyl oxalate, or any combination thereof.

5. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S2, the aromatic dicarboxylic acid compound is selected from one or more of the following: terephthalic acid or its esterified form, isophthalic acid or its esterified form, phthalic acid or its esterified form, phthalic anhydride or its esterified form, 1,4-naphthalenedicarboxylic acid or its esterified form, 2,7-naphthalenedicarboxylic acid or its esterified form, 2,6-naphthalenedicarboxylic acid or its esterified form, and 4,4'-biphenylenedicarboxylic acid or its esterified form; and / or, the aliphatic diol is selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, pentanediol, neopentanediol, 1,5-pentanediol, and 3-methyl -1,5-pentanediol, hexanediol, 1,4-cyclohexanediol, diethylene glycol, or 2,2,4-trimethyl-1,3-pentanediol, or any combination thereof; and / or, the polyether diol is selected from polyethylene glycol or polytetramethylene ether glycol, or a combination thereof; and / or, the catalyst is selected from sodium acetate, zinc acetate, manganese acetate, antimony acetate, tetrabutyl titanate, tetraisopropyl titanate, dibutyltin oxide, dibutyltin dilaurate, stannous octoate, antimony glycolide, or antimony trioxide, or any combination thereof; and / or, the antioxidant is selected from antioxidant 168, antioxidant 1010, antioxidant 1076, antioxidant 1098, and antioxidant 1330, or any combination thereof.

6. The method for preparing the UV-resistant polyether ester elastomer according to claim 5, characterized in that, In step S2, the molar ratio of the terminal hydroxy oxalate to the aromatic dicarboxylic acid compound, aliphatic diol, and polyether diol is (0.4–3.1):2.7:(1.2–3.9):0.3; the amount of the catalyst is 0.02–0.8% of the total mass of the terminal hydroxy oxalate, aromatic dicarboxylic acid compound, aliphatic diol, and polyether diol; and the amount of the antioxidant is 0.08–1.0% of the total mass of the terminal hydroxy oxalate, aromatic dicarboxylic acid compound, aliphatic diol, and polyether diol.

7. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S2, the esterification reaction is carried out at a temperature of 200–220°C and in a nitrogen or inert gas atmosphere.

8. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S2, the pre-condensation reaction is carried out at a temperature of 240–250°C and a pressure of 0.8–1.2 kPa.

9. The method for preparing the UV-resistant polyether ester elastomer according to claim 1, characterized in that, In step S2, the final polycondensation reaction is carried out at a temperature of 240–245°C and a pressure of no more than 30 Pa.

10. The application of a UV-resistant polyether ester elastomer prepared by the method according to any one of claims 1 to 9, characterized in that, The UV-resistant polyether ester elastomer is used to manufacture sealing strips, dust covers, air ducts, wires and cables, and industrial belts.

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