Thermoplastic polyester elastomer as well as preparation method and application thereof

Abstract

The invention provides a thermoplastic polyester elastomer as well as a preparation method and application thereof. The thermoplastic polyester elastomer comprises aromatic dibasic acid residues and aliphatic dihydric alcohol residues, on the basis that the total molar weight of the aliphatic dihydric alcohol residues is 100 mol%, the aliphatic dihydric alcohol residues comprise 65 to 85 mol% of micromolecular dihydric alcohol residues, 14 to 34 mol% of polytetrahydrofuran ether glycol residues and 0.1 to 5.2 mol% of polyethylene glycol residues. The thermoplastic polyester elastomer is short in forming period, high in production efficiency and good in appearance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a thermoplastic polyester elastomer and a preparation method and application thereof. Background Art

[0002] Thermoplastic polyester elastomer is a type of linear block copolymer with polyester hard segment and polyester or polyether soft segment, which has excellent mechanical properties, chemical solvent resistance, fatigue resistance, etc. Thermoplastic polyester elastomer does not need to be vulcanized and can be directly injection molded into various products. It has been widely used in the fields of automobile intake hose, transmission system dust cover, sports shoe sole, consumer electronics, medical equipment, railway gaskets, etc.

[0003] The Over-Molding process is to inject another material on the surface of the molded part to complete the secondary molding, so as to obtain a material that meets different performance requirements. Through the Over-Molding process, low-hardness thermoplastic elastomers can be injected and bonded with materials such as PC, ABS, and PC / ABS alloys. In automotive interiors, it can be used for soft skins, charging board skins, glove box skins, and other parts, providing good touch and scratch and wear resistance.

[0004] However, during the injection molding process, low-hardness thermoplastic elastomers require a long holding and cooling time due to their slow cooling and hardening speeds. This results in a long molding cycle, which affects production efficiency and is prone to appearance problems such as cloaking.

[0005] Therefore, developing a low-hardness thermoplastic polyester elastomer with a short molding cycle, high production efficiency and good appearance is a technical problem to be solved urgently in the field. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a thermoplastic polyester elastomer and a preparation method and application thereof. The thermoplastic polyester elastomer solves the problems of the prior art low-hardness thermoplastic polyester elastomer (hardness less than 40D) with long molding cycle, low production efficiency and poor product appearance performance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a thermoplastic polyester elastomer, which comprises aromatic dibasic acid residues and aliphatic diol residues; based on the total molar amount of the aliphatic diol residues as 100 mol%, the aliphatic diol residues comprise 65 to 85 mol% of small molecule diol residues, 14 to 34 mol% of polytetramethylene glycol residues and 0.1 to 5.2 mol% of polyethylene glycol residues.

[0009] In the present invention, polyethylene glycol has good compatibility with the hard segment of a thermoplastic polyester elastomer, has high molecular chain flexibility, and can induce rapid crystallization of the thermoplastic polyester elastomer during cooling and molding; by introducing polyethylene glycol residues into the molecular structure of the thermoplastic polyester elastomer, the thermoplastic polyester elastomer has a short molding cycle, high production efficiency and good appearance; and polytetrahydrofuran ether glycol can ensure basic physical properties of the thermoplastic polyester elastomer, such as mechanical properties, hydrolysis resistance, heat resistance, etc.; and by compounding polyethylene glycol residues and polytetrahydrofuran ether glycol residues with specific contents, the molding cycle of the thermoplastic polyester elastomer can be effectively shortened while ensuring that the thermoplastic polyester elastomer has good physical properties.

[0010] In the present invention, the molar ratio of the aromatic dibasic acid residue to the aliphatic diol residue in the thermoplastic polyester elastomer is (0.9-1.1):1.

[0011] It should be noted that the "residue" mentioned in the present invention refers to the organic structure introduced into the thermoplastic polyester elastomer by the relevant monomer through polymerization reaction, that is, the structural unit derived from the relevant monomer; for example, the aromatic dibasic acid residue refers to the structural unit derived from the aromatic dibasic acid.

[0012] In the present invention, 65-85 mol% of the small molecule diol residues can be, for example, 65 mol%, 66 mol%, 67 mol%, 68 mol%, 69 mol%, 70 mol%, 71 mol%, 72 mol%, 73 mol%, 74 mol%, 75 mol%, 76 mol%, 77 mol%, 78 mol%, 79 mol%, 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, 85 mol% or a range between any of the above values.

[0013] In the present invention, 14-34 mol% of polytetramethylene ether glycol residues may be, for example, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol% or any range between the above values; more preferably 19-28 mol%.

[0014] In the present invention, 0.1-5.2 mol% of polyethylene glycol residues may be, for example, 0.1 mol%, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, 1 mol%, 1.2 mol%, 1.4 mol%, 1.6 mol%, 1.8 mol%, 2 mol%, 2.2 mol%, 2.5 mol%, 2.8 mol%, 3 mol%, 3.2 mol%, 3.5 mol%, 3.8 mol%, 4 mol%, 4.2 mol%, 4.5 mol%, 4.8 mol%, 5 mol%, 5.1 mol% or any range between the above values; more preferably 0.5-3 mol%, particularly preferably 0.55-1.95 mol%.

[0015] In the present invention, when the polyethylene glycol residue content is too high or the polytetramethylene ether glycol residue content is too low, the physical properties of the thermoplastic elastomer are poor; when the polyethylene glycol residue content is too low or the polytetramethylene ether glycol residue content is too high, the molding cycle of the thermoplastic polyester elastomer is long; and when the small molecule diol residue and the polytetramethylene ether glycol residue are not compounded with the polyethylene glycol residue at a specific content, the molding cycle of the thermoplastic polyester elastomer is also long.

[0016] Preferably, the number average molecular weight of the polyethylene glycol residue is 580-6200, for example, 580, 590, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2200, 2400, 2600, 2800, 30 00, 3200, 3400, 3600, 3800, 4000, 4200, 4400, 4600, 4800, 5000, 5200, 5400, 5600, 5800, 6000, 6100, 6200 or any range between the above values; preferably, the number average molecular weight is 780-4200, and more preferably the number average molecular weight is 980-2200.

[0017] Preferably, the number average molecular weight of the polytetramethylene glycol residue is 950-4000, for example, it can be 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, ​​3000, 3100, 3200, 3400, 3600, 3800, 4000 or any range between the above values; more preferably, the number average molecular weight is 1700-3100.

[0018] In the present invention, the number average molecular weight of the polytetrahydrofuran ether diol residue and the polyethylene glycol residue is determined by the number average molecular weight of the raw material polytetrahydrofuran ether diol and the raw material polyethylene glycol, and the number average molecular weight of the polytetrahydrofuran ether diol and the polyethylene glycol can be obtained by testing with a gel permeation chromatograph, wherein the instrument model is: Waters ACQUITY APC; tetrahydrofuran is selected as the mobile phase, and the sample concentration is 1 mg / mL.

[0019] Preferably, the aromatic dibasic acid residue includes at least one of a terephthalic acid residue, a phthalic acid residue or an isophthalic acid residue; more preferably, it includes at least a terephthalic acid residue.

[0020] In the present invention, the molar percentage of terephthalic acid residues in the aromatic dibasic acid residues is ≥50%, more preferably ≥70%.

[0021] Preferably, the small molecule diol residue includes C2-C6 aliphatic diol residues, for example, C2, C3, C4, C5, C6 aliphatic diol residues.

[0022] Preferably, the small molecule diol residue includes at least one of an ethylene glycol residue, a 1,3-propylene glycol residue, a 1,4-butanediol residue, a pentanediol residue or a hexanediol residue.

[0023] In the present invention, the viscosity of the dilute solution of the thermoplastic polyester elastomer (mass concentration of 0.005 g / mL) is 1.0 to 1.72 dL / g; more preferably 1.15 to 1.67 dL / g; the viscosity test method comprises: weighing 0.125 g of the thermoplastic polyester elastomer, crushing it and dissolving it in 25 mL of a mixed solvent of phenol / o-dichlorobenzene (mass ratio of 60 / 40), filtering it through a sand core funnel, and testing its outflow time t with a capillary viscometer. 1 , the blank solvent elution time is t 0, the test temperature is 25°C. The dilute solution viscosity of the thermoplastic polyester elastomer is calculated according to the following formula.

[0024]

[0025] Where: [η]: dilute solution viscosity of thermoplastic polyester elastomer; t 1 : The time for the thermoplastic polyester elastomer solution to flow through the capillary viscometer, unit: s; t 0 : is the time for the solvent to flow through the capillary viscometer, unit is s; c: is the viscosity of the thermoplastic polyester elastomer solution, unit is g / 100mL.

[0026] Preferably, the hardness of the thermoplastic polyester elastomer is ≤40D, more preferably the hardness is 25-40D, and particularly preferably 30-40D.

[0027] In the present invention, the hardness of the thermoplastic polyester elastomer can be obtained by testing according to ISO7619-2010.

[0028] In a second aspect, the present invention provides a method for preparing the thermoplastic polyester elastomer according to the first aspect, the preparation method comprising the following steps:

[0029] The aromatic dibasic acid, the small molecule diol, the polytetrahydrofuran ether glycol and the polyethylene glycol are mixed and reacted to obtain the thermoplastic polyester elastomer.

[0030] Preferably, the mixed raw materials further include a catalyst and / or an antioxidant.

[0031] In the present invention, the mass of the catalyst is 0.01-0.1% of the total weight of the raw materials (i.e., the total weight of the aromatic dibasic acid, the small molecule diol, the polytetramethylene glycol and the polyethylene glycol), for example, it can be 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1% or any range between the above values; the catalyst includes but is not limited to titanate compounds; the mass of the antioxidant is 0.02-0.2% of the total weight of the raw materials, for example, it can be 0.02%, 0.04%, 0.06%, 0.08%, 0.1% or any range between the above values. .1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2% or any range between the above values; the antioxidant includes but is not limited to hindered phenol antioxidants (such as antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 1019, antioxidant 330, antioxidant 3114, antioxidant 1790, antioxidant 3125, antioxidant 245, antioxidant BHT, etc.), phosphite antioxidants (such as antioxidant 168, antioxidant PEP-36, antioxidant 626, antioxidant 686, antioxidant P-EPQ), etc.

[0032] Preferably, the reaction comprises: S1: reacting an aromatic dibasic acid with a small molecule diol to obtain a product A; S2: reacting the product A with polytetramethylene glycol and polyethylene glycol to obtain a product B; S3: subjecting the product B to a condensation reaction to obtain the thermoplastic polyester elastomer.

[0033] In the present invention, the polyester formed by the reaction of the aromatic dibasic acid and the small molecule diol is the hard segment of the thermoplastic polyester elastomer, and the polytetramethylene glycol and polyethylene glycol are the soft segments of the thermoplastic polyester elastomer.

[0034] Preferably, the reaction temperature in step S1 is 190-230°C, for example, it can be 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C or any range between the above values; the reaction time is 0.5-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or any range between the above values.

[0035] Preferably, the reaction temperature in step S2 is 190-230°C, for example, it can be 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C or any range between the above values; the reaction time is 0.5-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or any range between the above values.

[0036] Preferably, the temperature of the condensation reaction in step S3 is 235-255°C, for example, it can be 235°C, 240°C, 245°C, 250°C, 255°C or any range between the above values; the reaction pressure is ≤100Pa, for example, it can be 10Pa, 20Pa, 40Pa, 60Pa, 80Pa, 100Pa or any range between the above values; the reaction time is 2-4h, for example, it can be 2h, 2.5h, 3h, 3.5h, 4h or any range between the above values.

[0037] In the present invention, the reaction in step S1 is carried out in the presence of a protective atmosphere; the protective atmosphere includes but is not limited to nitrogen; the raw materials for the reaction in step S1 also include a catalyst and an antioxidant; the raw materials for the reaction in step S2 also include a catalyst.

[0038] In the present invention, the preparation method of the thermoplastic polyester elastomer comprises:

[0039] In the presence of a protective atmosphere, an aromatic dibasic acid, a small molecule diol, and a catalyst and an antioxidant in a formula amount of 40 to 60% are mixed, and the mixture is reacted at 190 to 230° C. for 0.5 to 3 hours; polytetrahydrofuran ether glycol and polyethylene glycol are added thereto, and the remaining catalyst is continued to react at 190 to 230° C. for 0.5 to 3 hours, and then the temperature is raised to 235 to 255° C., and the system pressure is reduced to below 100 Pa within 30 minutes, and the reaction is continued for 2 to 4 hours; stirring is stopped, and high-purity nitrogen is filled into the system, and the material is pressed out from a die, and the thermoplastic polyester elastomer is obtained through water cooling and pelletizing.

[0040] In a third aspect, the present invention provides a polyester composition, wherein the polyester composition comprises the thermoplastic polyester elastomer described in the first aspect.

[0041] Preferably, the polyester composition further comprises at least one of a filler, an auxiliary agent or a pigment.

[0042] In the present invention, the mass percentage of the thermoplastic polyester elastomer in the polyester composition is ≥20%, preferably ≥30%, further preferably ≥45%, and more preferably ≥55%.

[0043] In the present invention, various fillers, additives, pigments, etc. can be added according to actual needs; for example, the fillers include but are not limited to mineral powder, glass fiber, carbon fiber, etc.; the additives include but are not limited to flame retardants (such as melamine cyanurate, melamine polyphosphate, hypophosphite, aluminum hydroxide, magnesium hydroxide, phosphate flame retardants, etc.), antioxidants (such as antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 168, antioxidant 626, etc.), ultraviolet light absorbers (such as UV-P, UV-0, UV-9, UV-531, UV-1164, UV-1577, etc.), , UV-1600, UV-3030, UV-329, UV-326, UV-360, UV-328, etc.), light stabilizers (such as light stabilizer 944, light stabilizer 622, light stabilizer 770, light stabilizer 3853, light stabilizer 3529, light stabilizer 3346, light stabilizer LA-63, light stabilizer UV-123, light stabilizer 119, light stabilizer 3030, light stabilizer 2020, light stabilizer 5050, light stabilizer 144, light stabilizer UV-3034, light stabilizer 3150, light stabilizer 3159, etc.), etc.

[0044] In the present invention, the preparation method of the polyester composition comprises: mixing the components uniformly and extruding to obtain the polyester composition; the extrusion temperature is 180-230°C; the extrusion is carried out in a twin-screw extruder; the aspect ratio of the twin-screw extruder is 36-60:1, and the material stays in the screw for 40-60s.

[0045] In a fourth aspect, the present invention provides an automobile interior, wherein the raw materials for preparing the automobile interior include the thermoplastic polyester elastomer described in the first aspect or the polyester composition described in the third aspect.

[0046] The automobile interior includes automobile door panel skin, instrument panel skin, charging panel skin, etc.; in addition, the thermoplastic polyester elastomer can also be used to prepare cup holder cushions, etc.

[0047] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The thermoplastic polyester elastomer provided by the present invention can effectively shorten its molding cycle, improve production efficiency, and obtain products with good appearance by introducing polyethylene glycol residues into the molecular structure of the thermoplastic polyester elastomer and compounding polyethylene glycol residues and polytetramethylene glycol residues with specific contents while ensuring that the thermoplastic polyester elastomer has good physical properties. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] The materials used in the present invention can be purchased from the market or prepared by conventional methods; unless otherwise specified, the materials used in all embodiments and comparative examples of the present invention are as follows:

[0052] Terephthalic acid: commercially available industrial grade purified terephthalic acid, produced by INEOS CHEMICAL.

[0053] Isophthalic acid: commercially available industrial grade isophthalic acid, produced by LOTTE CHEMICAL.

[0054] 1,4-Butanediol: Commercially available industrial-grade 1,4-butanediol, produced in Tunhe, Lanshan, Xinjiang.

[0055] Hexanediol: purchased from Anaiji Chemical.

[0056] Polytetramethylene glycol (PTMG): PTMG of different molecular weights is produced by PTG in South Korea.

[0057] Polyethylene glycol (PEG): PEG with different molecular weights was purchased from Anaiji Chemical.

[0058] Polypropylene glycol (PPG): PPG-2000 was purchased from Anaiji Chemical.

[0059] Examples 1 to 16, Comparative Examples 1 to 4

[0060] Examples 1 to 16 and Comparative Examples 1 to 4 respectively provide a thermoplastic polyester elastomer, wherein the thermoplastic polyester elastomer contains an aromatic dibasic acid residue and an aliphatic diol residue; the molar ratio of the aromatic dibasic acid residue to the aliphatic diol residue is 1:1; the content composition of the aromatic dibasic acid residue (based on the total molar content of the aromatic dibasic acid residue as 100 mol%), the composition of the aliphatic diol residue (based on the total molar content of the aliphatic diol residue as 100 mol%), and the dilute solution viscosity and hardness of the thermoplastic polyester elastomer are as shown in Tables 1 to 3; wherein, “ / ” indicates that the thermoplastic polyester elastomer does not contain the residue.

[0061] Among them, the content of each residue in the thermoplastic polyester elastomer is determined by 1 H NMR measurement. Specifically, the thermoplastic polyester elastomer was dissolved in CDCl 3 / CF 3 COOD (volume ratio of about 9 / 1) was tested on a Bruker 400MHz NMR spectrometer, and the molar percentage of each residue was calculated based on the integrated area. Taking terephthalic acid, 1,4-butanediol, PEG, and PTMG as examples, the content of each component was calculated according to the following formula.

[0062] Terephthalic acid:

[0063] Isophthalic acid:

[0064] 1,4-Butanediol:

[0065]

[0066] PTMG:

[0067]

[0068] PEG:

[0069]

[0070] Where: S 8.1 (terephthalic acid), S 7.59 (isophthalic acid), S 4.5 (1,4-Butanediol), S 3.7 (PEG), S 3.6 (PTMG), S 2.0 (1,4-Butanediol), S 1.7(PTMG) are 1 The integrated areas of the absorption peaks at 8.1 ppm, 7.59 ppm, 4.5 ppm, 3.7 ppm, 3.6 ppm, 2.0 ppm, and 1.7 ppm in the H NMR spectrum.

[0071] The preparation method of the thermoplastic polyester elastomer comprises:

[0072] Aromatic dibasic acid, small molecule diol and catalyst (butyl titanate, the mass is 0.025% of the total mass of aromatic dibasic acid, small molecule diol and polytetramethylene glycol) and antioxidant 1010 (0.05% of the total mass of aromatic dibasic acid, small molecule diol and polytetramethylene glycol) are mixed and reacted at 210°C for 1.5h; polytetramethylene glycol, polytetramethylene glycol, catalyst are added thereto. The agent (butyl titanate, the mass is 0.025% of the total mass of aromatic dibasic acid, small molecule diol and polytetramethylene glycol, polyethylene glycol) is continued to react at 210° C. for 1.5 hours, the temperature is raised to 245° C., the system pressure is reduced to below 100 Pa within 30 minutes, and the reaction is continued for 3 hours; the stirring is stopped, high-purity nitrogen is filled into the system, the material is pressed out from the die, and the thermoplastic polyester elastomer is obtained after water cooling and pelletizing.

[0073] Table 1

[0074]

[0075]

[0076] Table 2

[0077]

[0078] Table 3

[0079]

[0080]

[0081] Application Examples

[0082] A polyester composition, in parts by weight, comprises 70 parts of a thermoplastic polyester elastomer and 30 parts of a flame retardant Exolit OP 1230 (produced by Clariant); the thermoplastic polyester elastomer is the thermoplastic polyester elastomer provided in Examples 1 to 16 and Comparative Examples 1 to 4. The preparation method of the polyester composition comprises: after uniformly mixing the components, feeding them into a twin-screw extruder through a loss-in-weight metering scale, extruding at 210° C., cooling, pelletizing, and drying to obtain the polyester composition. The length-to-diameter ratio of the twin-screw extruder used is 44:1, and the material stays in the screw for 50 seconds.

[0083] Among them, polyethylene glycol and thermoplastic polyester elastomer were mixed and extruded as a control group; that is, the thermoplastic polyester elastomer provided in comparative example 1 was mixed and extruded with additives and polyethylene glycol (PEG1200, 3% by mass of the thermoplastic polyester elastomer) to obtain a polyester composition.

[0084] Performance Testing

[0085] (1) Molding cycle: The polyester composition was injection molded into a block-shaped product of 40×10×5 mm. Under the same injection molding process conditions (injection molding temperature 210°C, injection speed and injection pressure were both set to 40%, holding pressure was set to 40%, and holding time was 4s), the cooling time was changed. The shortest cooling time under which the product could be demolded normally without deformation was recorded, and the molding speed was judged by comparing the cooling time.

[0086] (2) Hardness: The hardness of the thermoplastic polyester elastomers provided in Examples 1 to 16 and Comparative Examples 1 to 4 was tested; the reference standard was ISO7619-2010.

[0087] The specific test results are shown in Table 4, and “-” means no test is required.

[0088] Table 4

[0089]

[0090]

[0091] As can be seen from Table 4, the thermoplastic polyester elastomer provided by the present invention can effectively shorten its molding cycle, improve production efficiency, and obtain products with good appearance by introducing polyethylene glycol residues into the molecular structure of the thermoplastic polyester elastomer and compounding polyethylene glycol residues and polytetramethylene glycol residues with specific contents, while ensuring that the thermoplastic polyester elastomer has good physical properties; in the injection molding process, the thermoplastic polyester elastomer has a cooling time of ≤25s, a short molding cycle, and improved production efficiency; and the thermoplastic polyester elastomer has a low hardness of less than 40D, which meets the performance requirements of low hardness polyester elastomers.

[0092] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermoplastic polyester elastomer, characterized in that The thermoplastic polyester elastomer comprises an aromatic dibasic acid residue and an aliphatic diol residue; Based on the total molar amount of the aliphatic diol residue being 100 mol %, the aliphatic diol residue comprises 65-85 mol % of small molecule diol residues, 14-34 mol % of polytetramethylene glycol residues and 0.1-5.2 mol % of polyethylene glycol residues.

2. The thermoplastic polyester elastomer according to claim 1, characterized in that The molar percentage of the polyethylene glycol residue in the aliphatic diol residue is 0.5 to 3 mol%; Preferably, the number average molecular weight of the polyethylene glycol residue is 580-6200, preferably 780-4200, more preferably 980-2200.

3. The thermoplastic polyester elastomer according to claim 1 or 2, characterized in that: The molar percentage of the polytetramethylene glycol residue in the aliphatic diol residue is 19-28 mol%.

4. The thermoplastic polyester elastomer according to any one of claims 1 to 3, characterized in that The number average molecular weight of the polytetramethylene ether glycol residue is 950-4000, and more preferably the number average molecular weight is 1700-3100.

5. The thermoplastic polyester elastomer according to any one of claims 1 to 4, characterized in that The aromatic dibasic acid residue includes at least one of a terephthalic acid residue, a phthalic acid residue or an isophthalic acid residue.

6. The thermoplastic polyester elastomer according to any one of claims 1 to 5, characterized in that: The small molecule diol residues include C2 to C6 aliphatic diol residues; Preferably, the small molecule diol residue includes at least one of ethylene glycol residue, 1,3-propylene glycol residue, 1,4-butanediol residue, pentanediol residue or hexanediol residue; Preferably, the viscosity of the dilute solution of the thermoplastic polyester elastomer at a mass concentration of 0.005 g / mL is 1.0 to 1.72 dL / g; Preferably, the hardness of the thermoplastic polyester elastomer is ≤40D.

7. A method for preparing a thermoplastic polyester elastomer according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The aromatic dibasic acid, the small molecule diol, the polytetrahydrofuran ether glycol and the polyethylene glycol are mixed and reacted to obtain the thermoplastic polyester elastomer.

8. The preparation method according to claim 7, characterized in that: The mixed raw materials also include a catalyst and / or an antioxidant; Preferably, the reaction comprises: S1: reacting an aromatic dibasic acid with a small molecular diol to obtain product A; S2: reacting the product A with polytetrahydrofuran ether glycol and polyethylene glycol to obtain product B; S3: subjecting the product B to a polycondensation reaction to obtain the thermoplastic polyester elastomer; Preferably, the reaction temperature in step S1 is 190-230° C., and the reaction time is 0.5-3 h; Preferably, the reaction temperature in step S2 is 190-230° C., and the reaction time is 0.5-3 h; Preferably, the temperature of the polycondensation reaction in step S3 is 235-255° C., the reaction pressure is ≤100 Pa, and the reaction time is 2-4 h.

9. A polyester composition, characterized in that The polyester composition comprises the thermoplastic polyester elastomer according to any one of claims 1 to 6; Preferably, the polyester composition further comprises at least one of a filler, an auxiliary agent or a pigment.

10. An automobile interior, characterized in that: The raw materials for preparing the automobile interior decoration include the thermoplastic polyester elastomer according to any one of claims 1 to 6 or the polyester composition according to claim 9.

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