Polyamide elastomer as well as preparation method and application thereof

Abstract

The invention discloses a polyamide elastomer as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. By reasonably controlling the covalent connection rate of the soft and hard sections of the polyamide elastomer and the types of the soft sections and the hard sections of the polyamide elastomer, the obtained polyamide elastomer is high in relative viscosity and excellent in mechanical property, rebound resilience, fatigue resistance and the like, and is suitable for preparing sports equipment, hoses, medical instruments and sealing materials.

Description

Technical Field

[0001] The present application relates to the field of polymer materials, and specifically relates to a polyamide elastomer, its preparation method and application. Background Art

[0002] Polyamide elastomer (TPAE) is a block copolymer composed of polyamide hard segments and aliphatic polyester or polyether soft segments. In 1979, Hughes Company in Germany took the lead in successfully developing TPAE. As a pearl among elastomer materials, TPAE has the advantages of high stretchability, wear resistance, solvent resistance, softness, high resilience, easy processing, etc., and is widely used in the fields of sports equipment, electronic products, medical devices, clothing, etc.

[0003] Currently, well-known foreign companies such as Arkema and Evonik synthesize TPAE by esterification reaction of polyamide hard segments and polyether alcohol soft segments. Due to the poor compatibility between polyamide hard and polyether alcohol soft segments, phase separation is likely to occur during the reaction, resulting in a low reaction efficiency between the two. In addition, this method requires the molar numbers of carboxyl groups of polyamide and hydroxyl groups of polyether alcohol in the system to be equal. Due to the relatively wide molecular weight distribution of polyamide hard segments and polyether alcohol soft segments, it is very difficult to ensure the accuracy of the end group value during measurement, greatly increasing the difficulty of this reaction and making it difficult to increase the molecular weight of the polymer at the end of the reaction. Therefore, it is difficult for the prior art to synthesize TPAE with a high relative viscosity and excellent properties such as mechanical properties, resilience, and fatigue resistance. Summary of the Invention

[0004] Based on the defects existing in the prior art, the purpose of the present application is to provide a polyamide elastomer, its preparation method and application, aiming to obtain a polyamide elastomer with a high relative viscosity and excellent properties such as mechanical properties (such as appropriate hardness, high tensile strength, high elongation at break), resilience, and fatigue resistance.

[0005] To achieve the above purpose, in the first aspect, the present application provides a polyamide elastomer, which includes polyamide hard segments and polyether alcohol soft segments, and the polyamide hard segments include at least one of AB-type polyamide and AABB-type polyamide;

[0006] The repeating units in the polyether alcohol soft segments include at least one of polytetrahydrofuran diol, polyethylene glycol, and polypropylene glycol;

[0007] The covalent connection rate of the hard and soft segments of the polyamide elastomer is ≥90%, the elongation at break is ≥800%, the resilience is ≥55%, and the carboxyl content is ≤35 mol / t;

[0008] The polyamide elastomer's 13The 13C-NMR spectrum has a doublet at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the doublet differ by 0.010 ppm to 0.090 ppm.

[0009] The covalent bonding rate of the hard and soft segments of the polyamide elastomer reflects the degree of covalent bonding between the polyamide hard segment and the polyether alcohol soft segment. A lower covalent bonding rate of the hard and soft segments of the polyamide elastomer means that more polyamide hard segments and polyether alcohol soft segments cannot be connected by covalent bonds, resulting in a lower viscosity of the elastomer and poor performance such as tensile strength, elongation at break, resilience, and fatigue resistance.

[0010] For the polyamide elastomer, the covalent bonding rate of the hard and soft segments can be adjusted by adjusting the types of amine compounds, the types of dibasic acids, the ratio of amine compounds to dibasic acids, the molecular weight of the polyether alcohol, the ratio of polyether alcohol to carboxylated polyamide prepolymer, the types of catalysts, the amount of catalysts, the temperature of the first heating reaction, the time of the first heating reaction, the temperature of the second heating reaction, and / or the time of the second heating reaction, etc.

[0011] The 13 The 13C-NMR spectrum has a doublet at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the doublet differ by 0.010 ppm to 0.090 ppm. For example, the resonance frequency positions of the doublet differ by 0.010 ppm, 0.015 ppm, 0.020 ppm, 0.025 ppm, 0.030 ppm, 0.035 ppm, 0.040 ppm, 0.045 ppm, 0.050 ppm, 0.055 ppm, 0.060 ppm, 0.065 ppm, 0.070 ppm, 0.075 ppm, 0.080 ppm, 0.085 ppm, 0.090 ppm or any range formed by any two of these values.

[0012] The 13The 13C-NMR spectrum has a doublet at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the doublet differ by 0.010 ppm to 0.090 ppm, indicating that small molecule diols are used in the preparation process of the polyamide elastomer. When small molecule diols (i.e., the number of carbon atoms in the molecule ≤ 8, such as 8, 7, 6, 5, 4, 3, or 2, etc.) are added in the preparation process of the polyamide elastomer, on the one hand, it is beneficial to increase the compatibility between the polyamide hard segment and the polyether alcohol soft segment, and avoid the problem of low probability of end group collision caused by phase separation during the reaction process; on the other hand, it can avoid the problem that the polymer molecular weight is difficult to increase and the material properties are poor due to the equimolar ratio problem at the end of the reaction between the soft and hard segments; on the third hand, the small molecule diols can preferentially undergo esterification reaction with the carboxyl groups in the polyamide prepolymer, reduce the carboxyl group content in the system, thereby further reducing the carboxyl value of the polyamide elastomer, improving the hydrolysis resistance of the elastomer, and improving the stability of the elastomer.

[0013] If the carboxyl group content of the polyamide elastomer is too high, it will cause poor thermal stability during injection molding of the elastomer, resulting in decomposition and deterioration of the mechanical properties of the injection molded product.

[0014] In this application, by reasonably controlling the polyamide elastomer to meet the above requirements, its relative viscosity is high, and its mechanical properties (such as appropriate hardness, high tensile strength, high elongation at break), resilience, fatigue resistance and other properties are excellent.

[0015] Exemplarily, the covalent bonding rate of the hard and soft segments of the polyamide elastomer is in the range of 93%, 94%, 95%, 96%, 97%, 98% or any range formed by any two of these values.

[0016] Exemplarily, the elongation at break of the polyamide elastomer is in the range of 800%, 900%, 1000%, 1100%, 1200%, 1300% or any range formed by any two of these values.

[0017] Exemplarily, the resilience of the polyamide elastomer is in the range of 55%, 58%, 60%, 62%, 64%, 66%, 68%, 70% or any range formed by any two of these values.

[0018] Exemplarily, the carboxyl group content of the polyamide elastomer is in the range of 34 mol / t, 32 mol / t, 30 mol / t, 28 mol / t, 26 mol / t, 24 mol / t, 20 mol / t, 18 mol / t, 16 mol / t, 14 mol / t, 12 mol / t, 10 mol / t, 8 mol / t, 6 mol / t, 4 mol / t, 2 mol / t or any range formed by any two of these values.

[0019] Preferably, the covalent bonding rate of the hard and soft segments of the polyamide elastomer is 93% to 95%.

[0020] When the covalent bonding rate of the hard and soft segments of the polyamide elastomer is controlled to be 93% to 95%, the obtained polyamide elastomer has a relatively higher relative viscosity and better mechanical properties.

[0021] The covalent bonding rate of the hard and soft segments of the above polyamide elastomer can be measured by the following method: Add TPAE (its mass is denoted as m2) to methanol with a mass 10 times that of TPAE, then extract at 65 °C for 8 h, then filter out the TPAE, dry it and weigh it. Denote this mass as m1, and calculate the covalent bonding rate of the hard and soft segments according to the following formula:

[0022] Covalent bonding rate of hard and soft segments = (m1 / m2) × 100%, where the units of m1 and m2 are both g.

[0023] Preferably, the 13 C-NMR spectrum of the polyamide elastomer has a doublet at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the doublet differ by 0.015 to 0.070 ppm. In this way, small molecule diols are more easily removed, which is beneficial to obtaining a polyamide elastomer with a relatively higher relative viscosity and better elongation at break of the polyamide elastomer.

[0024] The 13 C-NMR spectrum of the polyamide elastomer can be measured by the following method: Dissolve the elastomer in a mixed solution of hexafluoroisopropanol / deuterated chloroform (the volume ratio of hexafluoroisopropanol to deuterated chloroform is 2:1), perform nuclear magnetic resonance, and obtain 13 C-NMR spectrum.

[0025] Preferably, the carboxyl group content of the polyamide elastomer is 5 to 30 mol / t.

[0026] When the carboxyl group content of the polyamide elastomer is within the range of 5 to 30 mol / t, the hydrolysis resistance and stability of the elastomer are better.

[0027] The carboxyl group content of the above polyamide elastomer can be measured by the following method: Take 0.5 g of the elastomer, add 50 mL of benzyl alcohol, reflux and dissolve at 205 °C for 2 h, and then use an automatic potentiometric titrator and a calibrated KOH solution to titrate to measure the terminal carboxyl group content. The automatic potentiometric titrator can select the ZD-2 type automatic potentiometric titrator of Shanghai Yidian Scientific Instrument Co., Ltd.; the weight percentage of KOH in the KOH solution can be selected to be 0.5% to 1%.

[0028] Preferably, the number of carbon atoms in the repeating unit of the AB type polyamide is more than 10.

[0029] More preferably, the number of carbon atoms in the repeating unit of the AB-type polyamide is 11 to 12. For example, the number of carbon atoms in the repeating unit of the AB-type polyamide is 11 or 12.

[0030] When controlling the number of carbon atoms in the repeating unit of the AB-type polyamide to be more than 10, especially within the range of 11 to 12, the crystallinity of the polyamide elastomer is more suitable, and the hardness and softness are more appropriate, which is beneficial to achieving the balance of properties such as tensile strength, elongation at break, resilience, and fatigue resistance.

[0031] Preferably, the number of carbon atoms in the repeating unit of the AABB-type polyamide is more than 16.

[0032] More preferably, the number of carbon atoms in the repeating unit of the AABB-type polyamide is 16 to 25. For example, the number of carbon atoms in the repeating unit of the AABB-type polyamide is 16, 18, 20, 21, 23, 24, 25 or any range formed by any two of the above values.

[0033] When controlling the number of carbon atoms in the repeating unit of the AABB-type polyamide to be more than 16, especially within the range of 16 to 25, the crystallinity of the polyamide elastomer is more suitable, and the hardness and softness are more appropriate, which is beneficial to achieving the balance of properties such as tensile strength, elongation at break, resilience, and fatigue resistance.

[0034] The number of carbon atoms in the repeating unit of the AB-type polyamide refers to the number of carbon atoms in the raw material amine compound; the number of carbon atoms in the repeating unit of the AABB-type polyamide refers to the sum of the carbon atoms of the raw material amine compound and the dicarboxylic acid. By adjusting the types of amine compounds, dicarboxylic acids, etc., the number of carbon atoms in the repeating unit of the polyamide hard segment can be adjusted.

[0035] The number of carbon atoms in the repeating unit of the above polyamide hard segment can be measured by the following method: The carbon atoms of the repeating unit of the polyamide hard segment are calculated through the peak area on the quantitative 13 C-NMR spectrum. The specific calculation formula is as follows:

[0036] The number of carbon atoms in the repeating unit of the polyamide hard segment = (A 39～40ppm + A 35～37ppm + A 28～30ppm ) / A 177～ 178ppm A 39～40ppm represents the integral area of the peak at a chemical shift of 39 to 40 ppm, representing the vibration peak of the α carbon atom of the dicarboxylic acid chain segment on the repeating unit of the polyamide hard segment;

[0037] A 35～37ppmRepresents the integral area of the peak at a chemical shift of 35 - 37 ppm, representing the vibration peak of the α-carbon atom of the dibasic acid segment in the polyamide hard segment repeating unit.

[0038] A 28～30ppm Represents the integral area of the peak at a chemical shift of 28 - 30 ppm, representing the vibration peak of the α-carbon atom of the amine segment in the polyamide hard segment repeating unit;

[0039] A 177～178ppm Represents the integral area of the peak at a chemical shift of 177 - 178 ppm, representing the vibration peak of the carbon atom of the amide bond formed by the dibasic acid and amine in the polyamide hard segment repeating unit.

[0040] Preferably, the relative viscosity of the polyamide elastomer > 3.0, the hardness is 40 - 50 D, and the tensile strength ≥ 40 MPa. For example, the relative viscosity of the polyamide elastomer is 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8 or the range formed by any two of the above values; the hardness is 40 D, 42 D, 44 D, 46 D, 48 D, 50 D or the range formed by any two of the above values.

[0041] More preferably, the relative viscosity of the polyamide elastomer is 3.1 - 3.8, the tensile strength is 40 - 50 MPa, the elongation at break is 800% - 1300%, and the resilience is 55% - 70%.

[0042] The relative viscosity of the above polyamide elastomer can be measured by the following method: Dissolve TPAE in m-cresol to obtain a solution with a TPAE concentration of 0.1 g / mL, and measure the relative viscosity of the solution at 25 ± 0.01 °C, which is the relative viscosity of the polyamide elastomer.

[0043] The hardness of the above polyamide elastomer can be measured according to the standard GB / T2411 - 2008. The sample thickness is 4 mm, the temperature is 25 °C, and a D-type Shore hardness tester (model LX-D, Dongguan Runzhi Electronics Co., Ltd.) is selected for measurement. The hardness is the maximum value read within 1 s when the pressure seat of the hardness tester is in close contact with the sample.

[0044] The tensile strength and elongation at break of the above polyamide elastomer can be measured according to the standard GB / T 528 - 2009. The sample is a dumbbell-shaped specimen type 1 with a length of 115 mm, a width of 25 mm, and a thickness of 2 mm. The temperature is 25 °C, and the tensile rate is 50 mm / min.

[0045] The resilience of the above polyamide elastomer can be measured according to Standard GB / T1681-2009. The polyamide elastomer is injection-molded to obtain a cylindrical sample with a thickness of 12.5 mm and a diameter of 30 mm, and is measured according to Dimension IV in Appendix A, and the measurement temperature is 25 °C.

[0046] Preferably, the relative molecular weight of the polyamide hard segment is 500-2500 Da. The relative molecular weight of the polyamide hard segment can be selected from 500 Da, 700 Da, 1000 Da, 1200 Da, 1500 Da, 2000 Da, 2200 Da, 2500 Da or the range formed by any two of the above values.

[0047] More preferably, the relative molecular weight of the polyamide hard segment is 650-2150 Da.

[0048] When the relative molecular weight of the polyamide hard segment is 500-2500 Da, the compatibility between the polyamide hard segment and the polyether alcohol soft segment is good, which is beneficial to obtaining a polyamide elastomer with a high connection rate.

[0049] The relative molecular weight of the polyamide hard segment of the above polyamide elastomer can be measured by the following method: Dissolve the elastomer in a mixed solution of hexafluoroisopropanol / deuterated chloroform (the volume ratio of hexafluoroisopropanol to deuterated chloroform is 2:1), perform nuclear magnetic resonance to obtain 13 C-NMR spectrum, and calculate the molecular weight Mn of the polyamide hard segment by measuring the carbonyl peak area on the carbon spectrum.

[0050] Preferably, the AB-type polyamide includes at least one of the polyamide obtained by ring-opening of lactam and the polyamide obtained by condensation of amino carboxylic acid.

[0051] Preferably, the AABB-type polyamide includes the polyamide obtained by the reaction of a dibasic acid and a diamine.

[0052] Preferably, the relative molecular weight of the polyether alcohol soft segment is 500-5000 Da. For example, the relative molecular weight of the polyether alcohol soft segment is 500 Da, 700 Da, 1000 Da, 1200 Da, 1500 Da, 2000 Da, 2200 Da, 2500 Da, 2800 Da, 3000 Da, 3500 Da, 4000 Da, 4500 Da, 5000 Da or the range formed by any two of the above values.

[0053] More preferably, the relative molecular weight of the polyether alcohol soft segment is 650-2000 Da.

[0054] The relative molecular weight of the polyether alcohol soft segment is 500-5000 Da, especially when it is 650-2000 Da, the compatibility between the polyether alcohol soft segment and the polyamide hard segment is better, which is beneficial to obtaining a polyamide elastomer with a high connection rate.

[0055] Preferably, the mass percentage content of the polyamide hard segment in the polyamide elastomer is 47%-53%, such as the range formed by any two values among 47%, 48%, 49%, 50%, 51%, 52%, 53% or above.

[0056] Preferably, the mass percentage content of the polyether alcohol soft segment in the polyamide elastomer is 47%-53%, such as the range formed by any two values among 47%, 48%, 49%, 50%, 51%, 52%, 53% or above.

[0057] In a second aspect, the present application provides a method for preparing the polyamide elastomer, comprising the following steps:

[0058] Mix an amine compound, a dicarboxylic acid, a first catalyst and deionized water, and carry out a first heating reaction under an inert atmosphere. After the reaction is completed, carry out a first drying to obtain a carboxylated polyamide prepolymer;

[0059] Mix the carboxylated polyamide prepolymer, polyether alcohol, small molecule diol and a second catalyst, and carry out a second heating reaction under an inert atmosphere. After the reaction is completed, carry out a second drying to obtain a polyamide elastomer;

[0060] The number of carbon atoms in the molecule of the small molecule diol is ≤ 8, and the molar amount of the small molecule diol is 8%-20% of the molar amount of the polyether alcohol;

[0061] The second catalyst includes a zirconium-based catalyst;

[0062] The group of the amine compound contains at least one of -NH2 and -NH-.

[0063] Preferably, the number of carbon atoms in the molecule of the small molecule diol is 2-8. More preferably, the small molecule diol includes at least one of ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, and heptylene glycol. Compared with other diols, ethylene glycol, propylene glycol and butylene glycol have lower boiling points and are easy to remove, which is beneficial to saving energy and improving production efficiency.

[0064] Preferably, the zirconium-based catalyst includes at least one of tetrabutyl zirconate, zirconium propoxide, zirconium ethoxide, and zirconium acetate.

[0065] Preferably, the weight of the second catalyst is 0.15%-0.3% of the weight of the polyether alcohol.

[0066] Preferably, the polyether alcohol includes at least one of polytetrahydrofuran diol, polypropylene glycol, and polyethylene glycol.

[0067] Preferably, the molar ratio of the carboxylated polyamide prepolymer to the polyether alcohol is (0.90 - 1.20):1.

[0068] Preferably, the procedure for the second heating reaction is as follows: under a stirring speed of 40 - 60 rpm, first react at 200 - 220 °C and atmospheric pressure for 0.5 - 1 h, then raise the temperature to 240 - 260 °C, and then first evacuate to a pressure of 5 - 8 KPa at 240 - 260 °C, hold the pressure and evacuate for 0.5 - 1 h, and then evacuate to a pressure < 100 Pa, hold the pressure and react until the change in stirring power within 30 min is less than 10 W.

[0069] Preferably, the temperature of the second drying is 70 - 80 °C, and the time of the second drying is 24 - 48 h.

[0070] Preferably, the amine compound includes at least one of lactam, diamine, and aminocarboxylic acid. Exemplarily, the lactam includes at least one of undecanolactam and dodecanolactam; the diamine includes at least one of decanediamine, dodecane diamine, and tridecane diamine; the aminocarboxylic acid includes at least one of 11-aminoundecanoic acid and 12-aminododecanoic acid.

[0071] Preferably, the dicarboxylic acid includes at least one of adipic acid and dodecane dicarboxylic acid.

[0072] Preferably, the first catalyst includes at least one of sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, and phosphoric acid.

[0073] Preferably, the ratio of the sum of the molar amounts of NH2 and -NH- in the amine compound to the molar amount of carboxyl groups in the dicarboxylic acid is 1:(0.3 - 1.5).

[0074] Preferably, based on the total weight of the amine compound and the dicarboxylic acid, the weight of the first catalyst is 0.05% - 0.15%, and the weight of the deionized water is 10% - 30%.

[0075] Preferably, the procedure for the first heating reaction is as follows: first raise the temperature to 200 - 240 °C at a stirring speed of 30 - 70 rpm for 1 - 3 h, and then react at 200 - 240 °C for 0.5 - 2 h.

[0076] Preferably, between the first heating reaction and the first drying, the following steps are further included: first relieve the pressure, and then evacuate under a pressure condition of 5 - 8 KPa for 0.5 - 1 h to remove water vapor.

[0077] Preferably, the temperature of the first drying is 70-80° C., and the time of the first drying is 24-48 hours.

[0078] In a third aspect, the present application provides a use of the polyamide elastomer in sports equipment, hoses, medical devices, or sealing materials. For example, the sports equipment is a shoe sole, the medical device is a catheter, and the sealing material is a sealing ring.

[0079] Compared with the existing technology, the beneficial effect of the present application is that: by reasonably controlling the covalent connection rate of the soft and hard segments of the polyamide elastomer and the types of the hard and soft segments of the polyamide elastomer, the present application makes the obtained polyamide elastomer have high relative viscosity, excellent mechanical properties (such as appropriate hardness, high tensile strength, high elongation at break), resilience, fatigue resistance and other properties, and is suitable for the preparation of sports equipment, hoses, medical devices and sealing materials. DETAILED DESCRIPTION

[0080] In order to better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present application in detail, rather than to limit the present application. All other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present application. The experimental reagents and instruments involved in the implementation of this application are all commonly used ordinary reagents and instruments unless otherwise specified. In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions comprising the listed features.

[0081] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available raw materials. In addition, the components and raw materials used in each parallel experiment are all of the same type.

[0082] The polyether alcohol information used in the following examples and comparative examples is as follows:

[0083] Polyether alcohol A: Mn = 1000 Da, PTMEG1000, purchased from Sigma-Aldrich;

[0084] Polyether alcohol B: Mn = 1000 Da, polyethylene glycol 1000, purchased from Sigma-Aldrich.

[0085] Polyether alcohol C: Mn = 650 Da, PTMEG650, purchased from BASF;

[0086] Polyether alcohol D: Mn = 2000 Da, PTMEG2000, purchased from BASF;

[0087] Example 1

[0088] This embodiment provides a polyamide elastomer, and the preparation method of the polyamide elastomer comprises the following steps:

[0089] (1) Synthesis of carboxylated polyamide prepolymer: successively add an amine compound, a dicarboxylic acid, sodium hypophosphite and deionized water into an autoclave provided with a pressure explosion-proof port, vacuum-fill high-purity nitrogen gas (purity 99.99%, v / v, the same below) as a protective gas, first seal at a stirring speed of 50 rpm, heat up to 220 °C in 2 h, react at 220 °C for 1 h, then relieve the pressure until the pressure in the autoclave is normal pressure (i.e., 101.325 KPa, the same below), evacuate to 5 kPa and keep the pressure for 1 h to remove water vapor, stop heating and stirring, discharge the material, and vacuum-dry at 80 °C for 24 h to obtain a carboxylated polyamide prepolymer, wherein, based on the total weight of the amine compound and the dicarboxylic acid, the weight of sodium hypophosphite is 0.1%, and the weight of deionized water is 20%; the types and dosages of the amine compound and the dicarboxylic acid are shown in Table 1;

[0090] (2) Synthesis of TPAE: take the obtained carboxylated polyamide prepolymer and add it into an esterification reactor, then successively add a polyether alcohol, a small molecule diol and tetrabutyl zirconate, vacuum-fill high-purity nitrogen gas as a protective gas, first heat up to 210 °C at a stirring speed of 50 rpm and under normal pressure conditions, then react at 210 °C for 1 h, then heat up to 240 °C, evacuate to 5 kPa at 240 °C, keep the pressure and continue to react for 30 min, then evacuate to 70 Pa, keep the pressure and react until the change in stirring power within 30 min is 8 W, stop heating and stirring, discharge the material, and vacuum-dry at 80 °C for 24 h to obtain a polyamide elastomer, wherein the weight of tetrabutyl zirconate is 0.2% of the weight of the polyether alcohol, and the types of the small molecule diol, the ratio of the polyether alcohol to the carboxylated polyamide prepolymer, and the molar proportion of the small molecule diol relative to the polyether alcohol are shown in Table 1.

[0091] Examples 2 to 13 and Comparative Examples 1 to 7

[0092] Examples 2 to 13 and Comparative Examples 1 to 7 all provide a polyamide elastomer, and the raw materials and their dosages for preparing these polyamide elastomers are shown in Table 1 or Table 2, and the preparation process is the same as that of Example 1.

[0093] Table 1

[0094]

[0095]

[0096] Table 2

[0097]

[0098] The obtained polyamide elastomer is tested as follows:

[0099] Determination of the number of carbon atoms in the repeating unit of the polyamide hard segment: The carbon atoms in the repeating unit of the polyamide hard segment are calculated by the peak area on the quantitative 13 C-NMR spectrum. The specific calculation formula is as follows:

[0100] Number of carbon atoms in the repeating unit of the polyamide hard segment = (A 39～40ppm +A 35～37ppm +A 28～30ppm ) / A 177～ 178ppm A 39～40ppm represents the integrated area of the peak at a chemical shift of 39 - 40 ppm;

[0101] A 35～37ppm represents the integrated area of the peak at a chemical shift of 35 - 37 ppm;

[0102] A 28～30ppm represents the integrated area of the peak at a chemical shift of 28 - 30 ppm;

[0103] A 177～178ppm represents the integrated area of the peak at a chemical shift of 177 - 178 ppm;

[0104] Determination of the molecular weight Mn of the polyamide hard segment: The prepared TPAE is dissolved in a mixed solution of hexafluoroisopropanol / deuterated chloroform (the volume ratio of isopropanol to deuterated chloroform is 2:1), and nuclear magnetic resonance is carried out to obtain 13 C-NMR spectrum, and the molecular weight Mn of the polyamide hard segment is calculated by measuring the carbonyl peak area on the carbon spectrum;

[0105] Covalent connection rate of the hard and soft segments: Add TPAE (its mass is denoted as m2) to methanol with a mass 10 times that of it, then extract at 65 °C for 8 h, then filter out the TPAE and dry it for weighing, and denote this mass as m1. The covalent connection rate of the hard and soft segments is calculated according to the following formula:

[0106] Covalent connection rate of the hard and soft segments = (m1 / m2) × 100%, and the units of m1 and m2 are both g;

[0107] Content of carboxyl groups: Take 0.5 g of elastomer, add 50 mL of benzyl alcohol, reflux and dissolve at 205 °C for 2 h, and then use the ZD-2 type automatic potentiometric titrator of Shanghai Yidian Scientific Instrument Co., Ltd. and the calibrated KOH solution to titrate to measure the terminal carboxyl group content, where the weight percentage of KOH in the KOH solution is 1%;

[0108] Relative viscosity: Dissolve TPAE in m-cresol to obtain a solution with a TPAE concentration of 0.1 g / mL, and measure the relative viscosity of this solution at 25 ± 0.01 °C, that is, the relative viscosity of the polyamide elastomer;

[0109] Hardness: Measured in accordance with the standard GB / T 2411-2008. The thickness of the specimen is 4 mm, the temperature is 25 °C, and a Type D Shore hardness tester (model LX-D, Dongguan Runzhi Electronics Co., Ltd.) is used for measurement. The hardness is the maximum value read within 1 s when the pressure seat of the hardness tester is in close contact with the specimen.

[0110] Tensile strength and elongation at break: Measured in accordance with the standard GB / T 528-2009. The sample is a dumbbell-shaped specimen of Type 1 with a length of 115 mm, a width of 25 mm, and a thickness of 2 mm. The temperature is 25 °C, and the tensile rate is 50 mm / min.

[0111] Rebound resilience: Measured in accordance with the standard GB / T 1681-2009. Polyamide elastomer is injection molded to obtain cylindrical samples with a thickness of 12.5 mm and a diameter of 30 mm, and measured in accordance with Dimension IV in Appendix A. The measurement temperature is 25 °C.

[0112] Fatigue resistance: Measured in accordance with the standard GB / T13934-2006. The sample is a long strip-shaped specimen with a semi-circular cross-section. The temperature is 25 °C. "+" indicates that the polyamide elastomer has not cracked after 100,000 cycles of fatigue testing, and "-" indicates that the polyamide elastomer has a notch after 100,000 cycles of fatigue testing.

[0113] The test results are shown in Table 3 or Table 4.

[0114] Table 3

[0115]

[0116] Table 4

[0117]

[0118]

[0119] From the above data, it can be seen that the covalent bonding rate of the hard and soft segments of the polyamide elastomers obtained in each embodiment is ≥90%, the carboxyl content is ≤35 mol / t, the relative viscosity is high, and the mechanical properties (such as appropriate hardness, high tensile strength, and high elongation at break), rebound resilience, fatigue resistance and other properties are excellent. For example, the relative viscosity is >3.0, the hardness is 40-50 D, the tensile strength is ≥40 MPa, the elongation at break is ≥800%, the rebound resilience is ≥55%, and the fatigue resistance is qualified.

[0120] In Comparative Examples 1-2, since small molecule diols were not added, the obtained elastomers had a relatively low relative viscosity, a relatively high carboxyl content, and low covalent bonding rate of the hard and soft segments, tensile strength, elongation at break, rebound resilience and fatigue resistance.

[0121] Compared with Example 10, in Comparative Examples 3 to 4, due to the too low or too high addition amount of the small molecule diol, the relative viscosity, the covalent bonding rate of the hard and soft segments, the tensile strength, the elongation at break, the resilience and the fatigue resistance of the elastomer are low. This is because when the addition amount of the small molecule diol is too low, it cannot play the role of increasing the compatibility between the polyamide hard segment and the polyether alcohol soft segment; when the addition amount of the small molecule diol is too high, although it can help the polyamide hard segment and the polyether alcohol soft segment to be compatible, it is difficult to effectively remove, and it is impossible to effectively increase the molecular weight of the polyamide elastomer.

[0122] Comparing Examples 1 to 8 with Comparative Example 5, and Examples 9 to 13 with Comparative Example 6, it can be seen that when the number of carbon atoms in the repeating unit of the polyamide hard segment is too low, the relative viscosity, hardness, tensile strength, elongation at break, resilience and fatigue resistance of the elastomer are poor. This is because when the number of carbon atoms in the repeating unit of the polyamide hard segment is too low, the amide bond content is high, the polarity and melting point of the polymer molecule are high. Even with the help of the small molecule diol, the reaction effect between the polyamide and the polyether alcohol is still poor, and it is difficult to effectively increase the molecular weight of the polyamide elastomer.

[0123] Compared with Examples 1 to 5, in Comparative Example 7, the added small molecule diol is nonanediol (9 carbon atoms), resulting in poor relative viscosity, hardness, tensile strength, elongation at break, resilience and fatigue resistance of the elastomer. This is because nonanediol with a high carbon atom content has too high boiling point and is difficult to effectively remove, and it is impossible to effectively increase the molecular weight of the polyamide elastomer. Comparing Examples 1 and 5 to 7, it can be seen that when the 13 C-NMR spectrum has a doublet at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the doublet differ by 0.015 to 0.070 ppm, the obtained polyamide elastomer has a greater relative viscosity and a higher elongation at break.

[0124] Comparing Examples 1 to 6 and Example 8, it can be seen that when the covalent bonding rate of the hard and soft segments of the polyamide elastomer is in the range of 93% to 95%, its mechanical properties such as elongation at break and resilience are better.

[0125] It should be noted that the preparation process conditions of the above Examples 1 to 13 are only exemplary preparation process conditions, and they do not limit the process conditions of the present invention. Those of ordinary skill in the art can make adaptive adjustments to process conditions such as reaction temperature, reaction time, and stirring speed within the process conditions disclosed in the present invention.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application rather than to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A polyamide elastomer, characterized in that The polyamide elastomer comprises a polyamide hard segment and a polyether alcohol soft segment, wherein the polyamide hard segment comprises at least one of AB type polyamide and AABB type polyamide; The repeating units in the polyether alcohol soft segment include at least one of polytetramethylene glycol, polyethylene glycol, and polypropylene glycol; The polyamide elastomer has a covalent connection rate of soft and hard segments of ≥90%, an elongation at break ≥800%, a rebound resilience ≥55%, and a carboxyl content ≤35 mol / t; The polyamide elastomer 13 The C-NMR spectrum showed a double peak at 177.80 ppm to 178.20 ppm, and the resonance frequency positions of the double peaks differed by 0.010 ppm to 0.090 ppm.

2. The polyamide elastomer according to claim 1, wherein The covalent connection rate of the soft and hard segments of the polyamide elastomer is 93% to 95%.

3. The polyamide elastomer according to claim 1, wherein The resonance frequency positions of the double peaks differ by 0.015 ppm to 0.070 ppm.

4. The polyamide elastomer according to claim 1, wherein The carboxyl content of the polyamide elastomer is 5 to 30 mol / t.

5. The polyamide elastomer according to claim 1, wherein The polyamide elastomer has a relative viscosity greater than 3.0, a hardness of 40 to 50D, and a tensile strength greater than or equal to 40 MPa.

6. The polyamide elastomer according to claim 5, characterized in that The polyamide elastomer has a relative viscosity of 3.1 to 3.8, a tensile strength of 40 to 50 MPa, an elongation at break of 800% to 1300%, and a rebound resilience of 55% to 70%.

7. The polyamide elastomer according to claim 1, wherein At least one of the following conditions is met: A1. The relative molecular weight of the polyamide hard segment is 500 to 2500Da; A2. The AB type polyamide comprises a polyamide obtained by ring-opening of a lactam, a polyamide obtained by condensation of an aminocarboxylic acid, or at least one thereof; A3. The AABB-type polyamide includes a polyamide obtained by the reaction of a dibasic acid and a diamine; A4. The relative molecular weight of the polyether alcohol soft segment is 500 to 5000 Da, preferably 650 to 2000 Da.

8. The method for preparing a polyamide elastomer according to any one of claims 1 to 7, wherein: The following steps are involved: An amine compound, a dicarboxylic acid, a first catalyst and deionized water are mixed, and a first heating reaction is carried out under an inert atmosphere. After the reaction is completed, the mixture is dried for a first time to obtain a carboxylated polyamide prepolymer; The carboxylated polyamide prepolymer, polyether alcohol, small molecule diol and a second catalyst are mixed, and a second heating reaction is carried out under an inert atmosphere. After the reaction is completed, the mixture is dried for a second time to obtain a polyamide elastomer; The number of carbon atoms in the molecule of the small molecule diol is ≤8, and the molar weight of the small molecule diol is 8% to 20% of the molar weight of the polyether alcohol; The second catalyst includes a zirconium-based catalyst; The group of the amine compound includes at least one of -NH2 and -NH-.

9. The method for preparing a polyamide elastomer according to claim 8, wherein: At least one of the following conditions is met: B1. The number of carbon atoms in the molecule of the small molecule diol is 2 to 8, and preferably the small molecule diol includes at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and heptanediol; B2. The zirconium-based catalyst comprises at least one of tetrabutyl zirconate, zirconium propoxide, zirconium ethanol and zirconium acetate; B3. The weight of the second catalyst is 0.15% to 0.3% by weight of the polyether alcohol; B4. The polyether alcohol comprises at least one of polytetramethylene glycol, polypropylene glycol and polyethylene glycol; B5. The molar ratio of the carboxylated polyamide prepolymer and the polyether alcohol is (0.90 to 1.20): 1; B6. The second heating reaction procedure is as follows: at a stirring speed of 40 to 60 rpm, the reaction was carried out at 200 to 220 ° C and atmospheric pressure for 0.5 to 1 h and then heated to 240 to 260 ° C, and then evacuated to a pressure of 5 to 8 kPa at 240 to 260 ° C, and the pressure was maintained for 0.5 to 1 h, and then evacuated to a pressure of <100 Pa, and the reaction was maintained under pressure until the stirring power changed within 30 min. The amount was less than 10 W; B7. The second drying temperature is 70 to 80°C and the second drying time is 24 to 48 hours; B8. The amine compound includes at least one of a lactam, a diamine, and an aminocarboxylic acid; B9. The first catalyst comprises at least one of sodium hypophosphite, potassium hypophosphite, calcium hypophosphite and phosphoric acid; B10. The ratio of the sum of the molar amounts of NH2 and -NH- in the amine compound to the molar amount of the carboxyl group in the dicarboxylic acid is 1: (0.3 to 1.5); B11. Based on the total weight of the amine compound and the dicarboxylic acid, the weight of the first catalyst is 0.05% to 0.15%, and the weight of the deionized water is 10% to 30%; B12. The first heating reaction procedure is as follows: heating to 200-240°C for 1-3h with stirring at 30-70rpm, and then reacting at 200-240°C for 0.5-2h; B13. Between the first heating reaction and the first drying, the following steps are further included: first depressurizing, and then evacuating under pressure conditions of 5 to 8 kPa for 0.5 to 1 h; B14. The temperature of the first drying is 70-80°C and the time of the first drying is 24-48 hours.

10. Use of the polyamide elastomer according to any one of claims 1 to 7 in sports equipment, hoses, medical devices or sealing materials.

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