A semi-aromatic long carbon chain polyamide, and a preparation method and application thereof

Abstract

The application provides a semi-aromatic long carbon chain polyamide and a preparation method and application thereof, and the semi-aromatic long carbon chain polyamide comprises the following repeating units: 10T units derived from 1,10-decanediamine and terephthalic acid; 10X units derived from 1,10-decanediamine and C8-C14 aliphatic diacid; the mole amount of the 10T units is 7-33% based on 100% of the total mole amount of the 10T units and the 10X units; and the total content of end amino groups and end carboxyl groups in the semi-aromatic long carbon chain polyamide is <100 mol / t. Through the design and joint action of the repeating units and the end group content, the semi-aromatic long carbon chain polyamide has good toughness, excellent cooling liquid resistance, and can fully meet the performance requirements of an automobile cooling pipeline system.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a semi-aromatic long-chain polyamide, its preparation method, and its application. Background Technology

[0002] Driven by global policies promoting the goals of "carbon peaking and carbon neutrality," the electric vehicle industry has experienced rapid development. Compared to traditional gasoline vehicles, electric vehicles, due to the characteristics of their battery packs and electric motors, place higher demands on the length of cooling system piping and the degree of lightweighting. At the same time, their operating temperature environment has also changed. This shift has prompted the selection of materials to move from traditional thermosetting materials (such as vulcanized EPDM rubber with braided layers, which has problems such as non-recyclability and large wall thickness) to thermoplastic materials with better performance.

[0003] Currently, PA12 material is widely used in the electric vehicle industry for manufacturing cooling pipes due to its lightweight nature (density approximately 1.00-1.03 g / cm³). 3 With its advantages of good flexibility and high design freedom, PA12 exhibits significant benefits in achieving vehicle weight reduction, simplifying pipe layout design, and improving corrosion resistance and fatigue resistance. Furthermore, compared to rubber hoses, PA12 material also features thinner walls, smaller volume, shorter molding cycles, and recyclability. Of particular note is the use of long-chain polyamides as cooling pipe materials, which further enhances these advantages. These materials are typically derived from renewable plant raw materials, reducing carbon emissions at the source. Compared to traditional petroleum-based PA12, long-chain polyamides demonstrate superior performance in key properties such as hydrolysis resistance, flexibility, and low-temperature impact toughness, making them particularly well-suited to the durability and reliability requirements of cooling systems in new energy vehicles. Moreover, the recyclability of these materials aligns perfectly with the concept of a circular economy. Therefore, in new energy vehicles, especially hybrid models (where both fuel and electric drive systems require efficient cooling pipes), the use of long-chain polyamides not only meets the demands for lightweighting and recyclability but also reduces the product's carbon footprint throughout its entire lifecycle, making it an ideal material choice for driving the automotive industry towards green and sustainable development.

[0004] CN102070902A discloses a polyamide molding composition suitable for fluid conduits (e.g., fuel pipes, cooling pipes, oil pipes, etc.) having the following composition: (a) 40-90 wt% of a copolyamide consisting of: (a1) 10-40 mol% of 1,6-hexanediamine and 60-90 mol% of 1,10-decanediamine, and (a2) 65-85 mol% of terephthalic acid and 15-35 mol% of at least one other polyamide forming monomer, said other polyamide being selected from at least one of dicarboxylic acids, dodecyl lactam, aminododecanic acid and / or mixtures thereof containing 8-18 carbon atoms; (b) 10-40 wt% of macromolecular plasticizers, provided that a portion of these macromolecular plasticizers can be replaced by low molecular weight plasticizers; and (c) 0-20 wt% of additives and / or additional substances. This copolyamide is copolymerized with 65-85 mol% terephthalic acid, which raises the resin melting point to above 250℃, solving the problem of excessive deposits in pipeline resin materials during processing. However, the elongation at break of this resin is reduced to below 10%, resulting in a serious lack of toughness in the material.

[0005] CN115785662A discloses a composition for a polyamide hose for cooling pipes, comprising, by weight: 58-95 parts of high-end amine-based long-chain polyamide resin, 0-20 parts of plasticizer, 4-20 parts of toughening agent, 0-3 parts of color masterbatch, 0.1-3 parts of antioxidant, 0.1-3 parts of chain extender, and 0-1 parts of lubricant; wherein the high-end amine-based long-chain polyamide resin is a long-chain aliphatic polyamide with a terminal amine group content greater than 50%. This material uses maleic anhydride-grafted elastomer as a toughening agent to improve flexibility, but its elongation at break decreases significantly after treatment in coolant, and its coolant resistance is clearly insufficient.

[0006] Therefore, developing a long-chain polyamide material with high toughness and good coolant resistance is an urgent problem to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a semi-aromatic long-chain polyamide, its preparation method, and its applications. Through the design and combined effect of repeating units and end-group content, the semi-aromatic long-chain polyamide exhibits excellent toughness and coolant resistance, fully meeting the performance requirements of automotive cooling piping systems.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a semi-aromatic long-chain polyamide, the semi-aromatic long-chain polyamide comprising the following repeating units: 10T units derived from 1,10-decanediamine and terephthalic acid; 10X units derived from 1,10-decanediamine and C8-C14 aliphatic dicarboxylic acids; the molar amount of the 10T units is 7-33% based on the total molar amount of the 10T units and 10X units being 100%; the total content of terminal amino and terminal carboxyl groups in the semi-aromatic long-chain polyamide is <100 mol / t.

[0009] This invention has found that the toughness and durability of long-chain copolymer polyamides are affected by the content of copolymer components and end groups. Based on this, the semi-aromatic long-chain polyamide provided by this invention has, on the one hand, designed a specific ratio of aromatic structural units (10T units), and on the other hand, designed the total content of terminal amino and terminal carboxyl groups to be <100 mol / t. Through the design and combined effect of repeating units and end group content, the semi-aromatic long-chain polyamide exhibits excellent toughness and coolant resistance, which can fully meet the performance requirements of automotive cooling pipe systems.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] In this invention, taking the total molar amount of 10T and 10X units in the semi-aromatic long-chain polyamide as 100%, the molar amount of the 10T unit is 7-33%, for example, it can be 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, or 32%, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range. If the molar amount of the 10T unit is <7%, the amide bonds in the aliphatic segments of the polyamide are easily broken in the coolant, resulting in poor resistance to coolant. If the molar amount of the 10T unit is >33%, the excessive aromatic ring structure will destroy the regularity of the polymer chain segments, resulting in poor crystallization ability, more internal defects in the crystal, and easy entry of coolant into the material, thus reducing toughness and coolant resistance.

[0012] The total content of terminal amino and terminal carboxyl groups in the semi-aromatic long-chain polyamide is <100 mol / t, for example, it can be 50 mol / t, 55 mol / t, 60 mol / t, 65 mol / t, 70 mol / t, 75 mol / t, 80 mol / t, 85 mol / t, 90 mol / t, 95 mol / t or 98 mol / t, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. Preferably, it is 65-99 mol / t, more preferably 70-90 mol / t, and even more preferably 75-88 mol / t.

[0013] In this invention, the total end-group content of the semi-aromatic long-chain polyamide is <100 mol / t. This content, combined with a specific repeating unit structure, regulates the crystallinity, crystal size, and amorphous region characteristics of the polyamide, resulting in good flexibility and, in particular, outstanding coolant resistance. If the total end-group content of the semi-aromatic long-chain polyamide is ≥100 mol / t, the coolant can penetrate the amorphous region more easily, thus affecting the coolant resistance of the polyamide material.

[0014] In this invention, the C8-C14 aliphatic dicarboxylic acid can be an aliphatic dicarboxylic acid of C8, C9, C10, C11, C12, C13, or C14. As a preferred embodiment of this invention, the C8-C14 aliphatic dicarboxylic acid includes any one or a combination of at least two of 1,9-azelaic acid, 1,10-sebacic acid, 1,11-undecanoic acid, 1,12-dodecanoic acid, and 1,14-tetradecanoic acid, preferably 1,10-sebacic acid and / or 1,12-dodecanoic acid.

[0015] As a preferred embodiment of the present invention, the content of terminal amino groups in the semi-aromatic long-chain polyamide is 20-60 mol / t, for example, it can be 22 mol / t, 25 mol / t, 28 mol / t, 30 mol / t, 32 mol / t, 35 mol / t, 38 mol / t, 40 mol / t, 42 mol / t, 45 mol / t, 48 mol / t, 50 mol / t, 52 mol / t, 55 mol / t or 58 mol / t, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. Preferably, it is 25-58 mol / t, more preferably 35-45 mol / t.

[0016] As a preferred embodiment of the present invention, the content of terminal carboxyl groups in the semi-aromatic long-chain polyamide is 20-65 mol / t, for example, it can be 22 mol / t, 25 mol / t, 28 mol / t, 30 mol / t, 32 mol / t, 34 mol / t, 35 mol / t, 38 mol / t, 40 mol / t, 42 mol / t, 44 mol / t, 45 mol / t, 48 mol / t, 50 mol / t, 52 mol / t, 55 mol / t, 58 mol / t, 60 mol / t, 62 mol / t, or 64 mol / t, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. Preferably, it is 25-60 mol / t, more preferably 35-48 mol / t.

[0017] As a preferred embodiment of the present invention, the molar ratio of terminal amino groups to terminal carboxyl groups in the semi-aromatic long-chain polyamide is (0.4-1.5):1, for example, it can be 0.43:1, 0.45:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 0.98:1, 1:1, 1.02:1, 1.05:1, 1.08:1, 1.1:1, 1.2:1, 1.3:1 or 1.4:1, etc., preferably (0.9-1.1):1.

[0018] For example, the content of terminal carboxyl groups and terminal amino groups in the semi-aromatic long-chain polyamide can be obtained by potentiometric titration.

[0019] Specifically, the test method for the terminal amino group in the semi-aromatic long-chain polyamide is as follows: Take 0.5 g of semi-aromatic long-chain polyamide, then add 50 mL of phenol, and after complete dissolution, titrate the content of the terminal amino group with a standardized hydrochloric acid solution.

[0020] The test method for the terminal carboxyl groups in the semi-aromatic long-chain polyamide is as follows: Take 0.5 g of semi-aromatic long-chain polyamide, dissolve it in 50 mL of o-cresol, add 0.3 mL of formaldehyde after complete dissolution, and titrate the content of terminal carboxyl groups with a standardized potassium hydroxide solution.

[0021] As a preferred embodiment of the present invention, the relative viscosity of the semi-aromatic long-chain polyamide is 2.4-3.0, for example, it can be 2.45, 2.5, 2.55, 2.6, 2.65, 2.7, 2.75, 2.8, 2.85, 2.9 or 2.95, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0022] In this invention, the relative viscosity is measured using the method described in standard GB / T 12006.1-2009, in 98% concentrated sulfuric acid at 25±0.01℃, to determine the relative viscosity η of a polyamide with a concentration of 1 g / dL. r .

[0023] In a second aspect, the present invention provides a method for preparing a semi-aromatic long-chain polyamide as described in the first aspect, the method comprising: Using 1,10-decanediamine, terephthalic acid, and C8-C14 aliphatic dicarboxylic acids as raw materials, the semi-aromatic long-chain polyamide was obtained through salt formation reaction and melt polymerization reaction.

[0024] Preferably, with the total molar amount of terephthalic acid and C8-C14 aliphatic dicarboxylic acid as 100%, the molar amount of terephthalic acid is 10-30%, for example, it can be 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26% or 28%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0025] Preferably, with the total molar amount of the terephthalic acid and C8-C14 aliphatic dicarboxylic acid as 100%, the molar amount of the 1,10-decanediamine is 100-105%, for example, it can be 100.01%, 100.05%, 100.1%, 100.5%, 101%, 101.5%, 102%, 102.5%, 103%, 103.5%, 104%, or 104.5%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0026] As a preferred embodiment of the present invention, the raw materials further include an end-capping agent.

[0027] As a preferred embodiment of the present invention, the capping agent includes a monobasic acid and / or a monobasic amine, and more preferably any one or a combination of at least two of benzoic acid, cyclohexanecarboxylic acid, acetic acid, stearic acid, lauric acid, and dodecylamine.

[0028] As a preferred embodiment of the present invention, with the total molar amount of the terephthalic acid and C8-C14 aliphatic dicarboxylic acid as 100%, the molar amount of the capping agent is 0.01-5%, for example, 0.02%, 0.05%, 0.08%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 4.8%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0029] As a preferred embodiment of the present invention, the raw materials further include antioxidants and / or catalysts.

[0030] As a preferred embodiment of the present invention, the antioxidant includes any one or a combination of at least two of the following: hindered amine antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and phosphite antioxidants.

[0031] Preferably, the antioxidant includes N,N The following is a combination of any one or at least two of the following: '-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098), pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), and sodium phosphite (antioxidant H10).

[0032] As a preferred embodiment of the present invention, based on the total mass of the raw materials as 100%, the mass of the antioxidant is 0.01-0.2%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.18%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0033] In this invention, "total mass of raw materials" refers to the total mass of 1,10-decanediamine, terephthalic acid, C8-C14 aliphatic dicarboxylic acid, capping agent, antioxidant (if any), and catalyst (if any), and can also be understood as the total mass of materials other than solvents.

[0034] As a preferred embodiment of the present invention, the catalyst comprises any one or a combination of at least two of phosphoric acid, alkali metal phosphate, hypophosphoric acid, and alkali metal hypophosphoric acid.

[0035] As a preferred embodiment of the present invention, the mass of the catalyst is 0.01-0.2% based on the total mass of the raw materials as 100%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.18%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0036] As a preferred embodiment of the present invention, the salt formation reaction is carried out in the presence of a solvent.

[0037] As a preferred embodiment of the present invention, the solvent includes water.

[0038] As a preferred embodiment of the present invention, with the total mass of the salt-forming reaction system being 100%, the mass of the solvent is 5-40%, for example, it can be 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, or 38%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0039] In this invention, "total mass of the system for salt formation reaction" represents the total mass of 1,10-decanediamine, terephthalic acid, C8-C14 aliphatic dicarboxylic acid, capping agent, antioxidant (if any), catalyst (if any), and solvent.

[0040] As a preferred embodiment of the present invention, the preparation method includes the following steps: 1,10-decanediamine, terephthalic acid, C8-C14 aliphatic dicarboxylic acid, end-capping agent, optionally catalyst, optionally antioxidant and solvent are added to a reaction apparatus to carry out a salt formation reaction, followed by water displacement and heating, and then melt polymerization under vacuum conditions to obtain the semi-aromatic long carbon chain polyamide.

[0041] Preferably, the salt formation reaction is carried out in a protective atmosphere.

[0042] Preferably, the protective atmosphere includes any one or a combination of at least two of nitrogen, argon, and helium atmospheres.

[0043] As a preferred embodiment of the present invention, the temperature of the salt formation reaction is 170-220℃, for example, it can be 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃ or 215℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0044] Preferably, the time taken to raise the temperature to the salt-forming reaction temperature is 0.5-3 h, for example, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.5 h, or 2.8 h, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. The salt-forming reaction can occur during the heating process. After the temperature reaches the target temperature for the salt-forming reaction (170-220℃), there is no need to hold the temperature; continue to drain water and raise the temperature until the temperature reaches the target temperature for the melt polymerization reaction (270-295℃).

[0045] As a preferred embodiment of the present invention, the temperature of the melt polymerization reaction is 270-295℃, for example, it can be 272℃, 275℃, 278℃, 280℃, 282℃, 285℃, 288℃, 290℃, 292℃ or 294℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0046] As a preferred embodiment of the present invention, the melt polymerization reaction time is 1-3 h, for example, it can be 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.5 h, 2.6 h or 2.8 h, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0047] As a preferred embodiment of the present invention, the preparation method includes: adding 1,10-decanediamine, terephthalic acid, C8-C14 aliphatic dicarboxylic acid, end-capping agent, optionally catalyst, optionally antioxidant and solvent to a reaction apparatus; carrying out a salt formation reaction by heating to 170-220°C within 0.5-3 h under a protective atmosphere and stirring conditions; then, under stirring conditions, draining water and heating to 270-295°C; performing a melt polymerization reaction at this temperature under vacuum and holding at 270-295°C for 1-3 h; increasing the molecular weight of the polymer by removing the formed water to obtain the semi-aromatic long carbon chain polyamide.

[0048] Thirdly, the present invention provides an application of the semi-aromatic long-chain polyamide as described in the first aspect in cooling systems, automotive parts, electrical appliances, or energy storage devices.

[0049] Thirdly, the present invention provides a cooling pipe material comprising the semi-aromatic long-chain polyamide as described in the first aspect.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects: The semi-aromatic long-chain polyamide provided by this invention, through the design and combined effect of repeating units and end group content, has good toughness and excellent coolant resistance, which can fully meet the performance requirements of automotive cooling pipe systems. Detailed Implementation

[0051] To facilitate understanding of the present invention, specific embodiments are provided to further illustrate the technical solution of the present invention. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0052] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0053] In the following specific embodiments, the test methods for the parameters of semi-aromatic long-chain polyamides are as follows: (1) Content of terminal amino groups The potentiometric titration method was used. 0.5 g of the semi-aromatic long-chain polyamide to be tested was weighed, and then 50 mL of phenol was added. After complete dissolution, the content of the terminal amino groups was titrated with a standardized hydrochloric acid solution.

[0054] (2) Content of terminal carboxyl groups The potentiometric titration method was used. 0.5 g of the semi-aromatic long-chain polyamide to be tested was weighed, and then 50 mL of o-cresol was added. After complete dissolution, 0.3 mL of formaldehyde aqueous solution (formaldehyde concentration of 37 wt%) was added, and the content of terminal carboxyl groups was titrated with a standardized KOH solution.

[0055] (3) Relative viscosity The relative viscosity η of polyamide with a concentration of 1 g / dL was tested in 98% concentrated sulfuric acid at 25±0.01℃ using the method in standard GB / T 12006.1-2009. r .

[0056] (4) Coolant resistance A standard tensile specimen was prepared according to the method in standard GB / T 1040.1-2018, and its elongation at break was tested and recorded as E0. Ethylene glycol and water were mixed at a volume ratio of 1:1 to prepare a coolant. The standard tensile specimen was immersed in the coolant and treated at 120°C for 2000 h. Then, the elongation at break was tested according to the method in GB / T 1040.1-2018 and recorded as E1. The elongation at break retention rate after coolant treatment = 100% × E1 / E0.

[0057] In the following specific embodiments of the present invention, the materials for which no preparation method is provided are all commercially available chemicals, and the specific information is as follows: The following will use several embodiments as examples to describe in detail the semi-aromatic long carbon chain polyamide and its preparation method according to the present invention, but the semi-aromatic long carbon chain polyamide and its preparation method are not limited to these embodiments.

[0058] Examples 1-10, Comparative Examples 1-3 A semi-aromatic long-chain polyamide comprising 10T units derived from 1,10-decanediamine and terephthalic acid and 10X units derived from 1,10-decanediamine and aliphatic dicarboxylic acids; its preparation method is as follows: In a pressure vessel equipped with a magnetically coupled stirrer, condenser, gas inlet, feed inlet, and pressure explosion-proof port, 1,10-decanediamine, terephthalic acid, aliphatic dicarboxylic acid, and stearic acid were added in the proportions shown in Tables 1 and 2. Antioxidant 1098, sodium hypophosphite, and deionized water were then added. The mass of the antioxidant and sodium hypophosphite was 0.1% of the total mass of the raw materials, and the mass of the deionized water was 20% of the total mass of the system. After evacuation, high-purity nitrogen was introduced as a protective gas. The temperature was raised to 200°C within 2 hours under stirring to carry out a salt formation reaction. Then, water was drained under stirring, and the temperature of the reactants was raised to 290°C. The reaction was carried out under vacuum at 290°C for a period of time (as shown in Tables 1 and 2). The molecular weight of the polymer was increased by removing the formed water. After the reaction was completed, the semi-aromatic long-chain polyamide was discharged, and its specific data are shown in Tables 1 and 2.

[0059] Table 1 Table 2 In Table 2, the preparation method of Comparative Example 4 is as follows: 1,10-decanediamine, terephthalic acid, 1,12-dodecanoic acid, and stearic acid are added to a pressure vessel equipped with a magnetically coupled stirrer, condenser, gas inlet, feed inlet, and pressure explosion-proof port according to the proportions shown in Table 2. Antioxidant 1098, sodium hypophosphite, and deionized water are then added. The mass of the antioxidant and sodium hypophosphite is 0.1% of the total mass of the raw materials, and the mass of deionized water is 20% of the total mass of the system. After evacuation, high-purity nitrogen is introduced as a protective gas. The temperature is raised to 100℃ within 0.5 h, and the salt formation reaction is carried out at a constant temperature for 1 h. Then, the temperature is raised to 210℃ within 2 h. During this period, the pressure is controlled to not exceed 1.7 MPa by venting the gas inside the vessel. Prepolymerization is carried out at a constant temperature for 2 h. Afterward, the gas is uniformly released to atmospheric pressure within 1.5 h. After cooling to room temperature, the material is discharged. The resulting white prepolymer is pulverized, vacuum dried, and then placed in a reaction vessel and heated to 160℃ for solid-phase polymerization under vacuum conditions. h, after cooling to room temperature, the material is discharged to obtain semi-aromatic long carbon chain polyamide.

[0060] According to the data in Table 1, the semi-aromatic long-chain polyamide provided by this invention has a molar percentage of 10T units containing aromatic structures in the repeating unit of 10-30%, and a total content of terminal amino and terminal carboxyl groups of <100 mol / t. Through the design and combined effect of the repeating unit and terminal group content, the semi-aromatic long-chain polyamide has good resistance to coolant. After treatment with coolant at 120℃ for 2000 h, the elongation at break is >20%, which can reach 22-30%, and the elongation at break retention rate is ≥19%.

[0061] Comparing Examples 1-3 with Comparative Examples 1-2, it can be seen that introducing an appropriate amount of repeating units containing aromatic rings into the repeating units of polyamide in this invention can improve the material's resistance to coolant. However, when the content of 10T units derived from 1,10-decanediamine and terephthalic acid increases, the original regular molecular structure is disrupted, resulting in more internal defects in the material, making it easier for coolant to enter the material and thus leading to a lower elongation at break. Conversely, when the content of 10T units is too low, the amide bonds in the aliphatic segments are easily broken in the coolant, resulting in poor resistance to coolant.

[0062] Comparing Example 2 and Comparative Examples 3-4, it can be seen that when the total content of terminal amino and terminal carboxyl groups in the polyamide is >100 mol / t, the end group content can affect the affinity of the amorphous region for the coolant. Therefore, when the end group content is high, the coolant can penetrate the amorphous region more easily, thus affecting the performance of the material.

[0063] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A semi-aromatic long-chain polyamide, characterized in that, The semi-aromatic long-chain polyamide comprises the following repeating units: Derived from the 10T unit of 1,10-decanediamine and terephthalic acid; 10X unit derived from 1,10-decanediamine and C8-C14 aliphatic dicarboxylic acids; With the total molar amount of 10T unit and 10X unit being 100%, the molar amount of 10T unit is 7-33%; The total content of terminal amino and terminal carboxyl groups in the semi-aromatic long-chain polyamide is <100 mol / t.

2. The semi-aromatic long-chain polyamide according to claim 1, characterized in that, The C8-C14 aliphatic dicarboxylic acid includes any one or a combination of at least two of 1,9-azelaic acid, 1,10-sebacic acid, 1,11-undecanoic acid, 1,12-dodecanoic acid, and 1,14-tetradecanoic acid, preferably 1,10-sebacic acid and / or 1,12-dodecanoic acid.

3. The semi-aromatic long-chain polyamide according to claim 1, characterized in that, The content of terminal amino groups in the semi-aromatic long-chain polyamide is 20-60 mol / t; And / or, the content of terminal carboxyl groups in the semi-aromatic long-chain polyamide is 20-65 mol / t; And / or, the total content of terminal amino and terminal carboxyl groups in the semi-aromatic long carbon chain polyamide is 65-99 mol / t; And / or, the molar ratio of terminal amino groups to terminal carboxyl groups in the semi-aromatic long-chain polyamide is (0.9-1.1):

1.

4. The semi-aromatic long-chain polyamide according to claim 1, characterized in that, The relative viscosity of the semi-aromatic long-chain polyamide is 2.4-3.

0.

5. A method for preparing a semi-aromatic long-chain polyamide as described in any one of claims 1-4, characterized in that, The preparation method includes: Using 1,10-decanediamine, terephthalic acid, and C8-C14 aliphatic dicarboxylic acids as raw materials, the semi-aromatic long-chain polyamide was obtained through salt formation reaction and melt polymerization reaction.

6. The preparation method according to claim 5, characterized in that, The raw materials also include end-capping agents; Preferably, the capping agent comprises a monobasic acid and / or a monobasic amine, and more preferably any one or a combination of at least two of benzoic acid, cyclohexanecarboxylic acid, acetic acid, stearic acid, lauric acid, and dodecylamine; Preferably, the molar amount of the capping agent is 0.01-5%, based on the total molar amount of the terephthalic acid and C8-C14 aliphatic dicarboxylic acid as 100%. Preferably, the raw materials further include antioxidants and / or catalysts; Preferably, the antioxidant includes any one or a combination of at least two of the following: hindered amine antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and phosphite antioxidants. Preferably, the antioxidant comprises 0.01-0.2% of the total mass of the raw materials (100%). Preferably, the catalyst comprises any one or a combination of at least two of phosphoric acid, alkali metal phosphate, hypophosphoric acid, and alkali metal hypophosphoric acid. Preferably, the mass of the catalyst is 0.01-0.2% based on the total mass of the raw materials (100%).

7. The preparation method according to claim 5, characterized in that, The salt-forming reaction is carried out in the presence of a solvent; Preferably, the solvent includes water; Preferably, the mass of the solvent is 5-40% based on the total mass of the salt-forming reaction system being 100%.

8. The preparation method according to claim 5, characterized in that, The preparation method includes the following steps: 1,10-decanediamine, terephthalic acid, C8-C14 aliphatic dicarboxylic acid, end-capping agent, optionally catalyst, optionally antioxidant and solvent are added to a reaction apparatus to carry out a salt formation reaction, followed by water displacement and heating, and then melt polymerization reaction under vacuum conditions to obtain the semi-aromatic long carbon chain polyamide. Preferably, the temperature of the salt-forming reaction is 170-220℃; Preferably, the temperature of the melt polymerization reaction is 270-295°C; Preferably, the melt polymerization reaction takes 1-3 hours.

9. The use of a semi-aromatic long-chain polyamide as described in any one of claims 1-4 in a cooling system, automotive component, electrical appliance, or energy storage device.

10. A cooling pipe material, characterized in that, The cooling pipe material includes the semi-aromatic long-chain polyamide as described in any one of claims 1-4.

Images