A bio-based transparent polyamide resin, its preparation method and applications

Abstract

A bio-based transparent polyamide resin, its preparation method, and its applications are disclosed. The general structural formula of the bio-based transparent polyamide resin is: [Formula omitted for brevity]. Wherein, R1 is a nitrogen-substituted meta-aromatic diacid group, R2 is a cyclic bio-based diacid group, and a or b = 4, 5, 6, or 10. The invention also discloses a method for preparing the bio-based transparent polyamide resin. The bio-based transparent polyamide resin can be used in the automotive industry, electronics, industrial machinery, medical devices, optical lenses, or aerospace fields. The bio-based transparent polyamide resin of this invention exhibits excellent adhesion, heat resistance, chemical resistance, and weather resistance; high glass transition temperature; high light transmittance; low water absorption; and diversified product range. The method of this invention uses renewable raw materials, has a simple process, short production cycle, and low cost, making it suitable for continuous industrial production.

Description

Technical Field

[0001] This invention relates to a polyamide resin, its preparation method, and its application, specifically to a bio-based transparent polyamide resin, its preparation method, and its application. Background Technology

[0002] Polyamide (PA) is a general term for resins containing repeating amide groups on their molecular chains. It is mainly formed by the condensation polymerization of lactams, amino acids, or polyamide salts (obtained by the salt formation reaction of diacids and diamines). It is the class with the largest output, the most varieties, and the widest application among the five major general-purpose engineering plastics. After more than 70 years of development, its application has expanded from spinning fibers to film packaging, engineering plastics and other fields.

[0003] Ordinary polyamide resins (such as PA6, PA66, PA610, etc.) are semi-crystalline polymers, typically white and translucent with a light transmittance between 50% and 80%. Due to the rapid development of the automotive and electronics industries, the poor transparency of polyamides has limited their application in certain fields, such as automotive oil cups, fuse covers, exhaust pipe connectors, and metering instruments. Transparent polyamides have thus emerged to address this need. Transparent polyamides are a special type of polyamide with high transparency, achieving a light transmittance of over 90%, approaching the transparency of polymethyl methacrylate and polycarbonate, while retaining the inherent high strength, wear resistance, and chemical corrosion resistance of polyamide materials. The preparation of transparent polyamides typically employs the following processes: 1) reducing the regularity of the polyamide molecular structure through copolymerization, such as PA6 / 12 and PA6I / 6T; 2) adding nucleating agents to alter crystallization behavior, forming microcrystals and reducing the crystal size to below the visible light wavelength. However, copolymerization must involve special dicarboxylic acid or diamine monomers, which has certain limitations. The degree to which the addition of nucleating agents improves the transparency of polyamides mainly depends on the type of nucleating agent and its dispersibility in the matrix.

[0004] CN120535743A discloses a yellowing-resistant transparent polyamide PATMDT / PACMT material and its preparation method. It uses terephthalic acid, 2,2,4-trimethylhexanediamine and 4,4'-diaminodicyclohexylmethane as raw materials. Although the resulting transparent polyamide resin has a narrow molecular weight distribution and excellent yellowing resistance and mechanical properties, the monomers used are all derived from traditional petrochemicals, which has a strong dependence on non-renewable resources and increases carbon emissions. On the other hand, the proportion of benzene rings and alicyclic rings in the molecular structure of the material is extremely high, resulting in poor toughness and making molding and processing difficult.

[0005] CN120647926A discloses a method for preparing bio-based polyamide materials and composite materials, using camphoric acid, triazole, sebacic acid, pentanediamine and caprolactam as raw materials. Although the resulting bio-based polyamide resin has excellent transparency and chemical resistance, and also has flame retardant, antibacterial and anti-ultraviolet properties, the nitrogen atoms in the triazole raw material are secondary and tertiary amines, which have weak basicity and reactivity, affecting the efficiency and purity of the salt formation reaction with camphoric acid, and thus affecting the relative viscosity and mechanical strength of the polyamide resin.

[0006] In summary, most of the raw materials reported for the preparation of transparent polyamides still originate from the traditional petrochemical industry. The limitation on monomer types severely affects the transparency, biodegradability, and other performance indicators of the resulting polyamide resins. Therefore, there is an urgent need to find suitable bio-based diacid and diamine monomers to copolymerize and obtain bio-based transparent polyamide resins with excellent adhesion, heat resistance, chemical resistance, and weather resistance, high glass transition temperature, high light transmittance, low water absorption, and diverse applications. Furthermore, it is crucial to develop a method for preparing bio-based transparent polyamide resins that utilizes renewable raw materials, has a simple process, short production cycle, low cost, and is suitable for continuous industrial production. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a bio-based transparent polyamide resin and its applications with excellent adhesion, heat resistance, chemical resistance and weather resistance, high glass transition temperature, high light transmittance, low water absorption and diversified products.

[0008] The technical problem to be further solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing bio-based transparent polyamide resin that uses renewable raw materials, has a simple process, a short production cycle, low cost, and is suitable for continuous industrial production.

[0009] The technical solution adopted by this invention to solve its technical problem is as follows: A bio-based transparent polyamide resin, the general structural formula of which is: Wherein, R1 is a meta-aromatic dicarboxylic acid group substituted with a nitrogen heterocyclic ring, R2 is a cyclic bio-based dicarboxylic acid group, and a or b = 4, 5, 6 or 10.

[0010] The inventive concept of this invention is as follows: The main molecular chain of the bio-based transparent polyamide resin of this invention contains meta-benzene rings, five-membered heterocyclic rings and other structures, which can exhibit excellent heat resistance and chemical resistance; the molecular side chain contains five-membered nitrogen heterocyclic structures such as pyrazole, triazole, tetraazole, imidazole and other structures, which breaks the tight packing between chains and can exhibit excellent light transmission and adhesion properties.

[0011] Preferably, the nitrogen-substituted meta-aromatic dicarboxylic acid group comprises: , , , , or One or more of the following. The side group of the meta-aromatic dicarboxylic acid is a five-membered nitrogen heterocyclic structure such as pyrazole, triazole, tetraazole, or imidazole.

[0012] Preferably, the cyclic bio-based dicarboxylic acid group comprises: , or One or more of the following. The main body of the cyclic bio-based dicarboxylic acid contains a five-membered heterocyclic structure such as thiophene, furan, or hydrogenated furan.

[0013] The technical solution adopted by the present invention to further solve its technical problem is as follows: A method for preparing a bio-based transparent polyamide resin, comprising the following steps: (1) Add nitrogen-substituted meta-aromatic dicarboxylic acid and bio-based diamine to pure water and stir to form salt to obtain component S1; add cyclic bio-based dicarboxylic acid and bio-based diamine to pure water and stir to form salt to obtain component S2; (2) The components S1, S2, catalyst, end-capping agent and anti-yellowing functional additive obtained in step (1) are put into a high temperature and high pressure reactor. After replacing the air in the reactor with inert gas, inert gas is introduced and melt polycondensation is carried out. Then inert gas is introduced again and the material is discharged to obtain bio-based transparent polyamide resin.

[0014] The inventive concept of this invention is as follows: This invention uses nitrogen-substituted meta-aromatic dicarboxylic acids, cyclic bio-based dicarboxylic acids, and bio-based diamines as basic raw materials, and with the cooperation of catalysts, end-capping agents, and anti-yellowing functional additives, bio-based transparent polyamide resins are obtained through salt formation and melt polycondensation. The catalyst mainly promotes the polycondensation reaction in the forward direction, the end-capping agent is used to control the relative viscosity of the resin and improve the weather resistance of the resin at the molecular level, and the anti-yellowing functional additives can work synergistically with the end-capping agent to further improve the weather resistance of the resin.

[0015] Preferably, in step (1), the molar ratio of the nitrogen-substituted meta-aromatic diacid to the bio-based diamine in component S1 is 0.97–1.00:1. Since the diamine may partially vaporize during heating to maintain pressure balance within the reactor, and this vapor may be discharged with water vapor, leading to an imbalance in the ratio of diacid to diamine, which could affect the relative viscosity of the final polymer, a slight excess of diamine is acceptable.

[0016] Preferably, in step (1), the amount of pure water used in component S1 is equivalent to 30-40% of the total mass of the nitrogen-substituted meta-aromatic dicarboxylic acid and the bio-based diamine. The amount of pure water used ensures that a clear solution is obtained at this concentration.

[0017] Preferably, in step (1), the nitrogen-substituted meta-aromatic dicarboxylic acid in component S1 includes one or more of the following: 5-(1H-pyrazol-4-yl)isophthalic acid, 5-(1H-1,2,4-triazol-1-yl)isophthalic acid, 5-(1H-tetrazole-5-yl)isophthalic acid, 5-(1H-tetrazole-1-yl)isophthalic acid, 4,6-bis(1H-imidazol-1-yl)isophthalic acid, or 4,6-bis(1H-1,2,4-triazol-1-yl)isophthalic acid.

[0018] Preferably, in step (1), the molar ratio of the cyclic bio-based diacid to the bio-based diamine in component S2 is 0.97 to 1.00:1. Since the diamine may partially vaporize during heating to maintain pressure balance within the reactor, and this vapor may be discharged with water vapor, leading to an imbalance in the ratio of diacid to diamine, which may affect the relative viscosity of the final polymer, a slight excess of diamine is acceptable.

[0019] Preferably, in step (1), the amount of pure water used in component S2 is equivalent to 30-40% of the total mass of the cyclic bio-based dicarboxylic acid and the bio-based diamine. The amount of pure water used ensures that a clear solution is obtained at this concentration.

[0020] Preferably, in step (1), the cyclic bio-based dicarboxylic acid in component S2 includes one or more of 2,5-thiophene dicarboxylic acid, 2,5-furan dicarboxylic acid, or tetrahydrofuran dicarboxylic acid.

[0021] Preferably, in step (1), the bio-based diamine in components S1 and S2 includes one or more of bio-based butylene diamine, pentanediamine, hexanediamine, or decanediamine. Bio-based diamines are aliphatic compounds and can be used to adjust the mechanical and water absorption properties of resins.

[0022] Preferably, in step (2), the mass ratio of component S1 to component S2 is 1:0.5 to 5.0 (more preferably 1:0.6 to 2.6). By adjusting the copolymerization ratio, the macroscopic properties of the resin can be precisely controlled, thereby matching the application needs of downstream applications.

[0023] Preferably, in step (2), the amount of catalyst, end-capping agent and anti-yellowing functional additive is 0.1 to 0.5% (more preferably 0.1 to 0.3%) of the total mass of component S1 and component S2.

[0024] Preferably, in step (2), the catalyst includes one or more of sodium hypophosphite, potassium hypophosphite, or magnesium hypophosphite.

[0025] Preferably, in step (2), the capping agent includes one or more of 4-amino-2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, or bis(2,2,6,6-tetramethylpiperidine-4-yl)amine. The capping agent contains amino or hydroxyl functional groups that can react with the terminal carboxyl groups of the polyamide, enabling molecular-level bonding rather than simple blending and dispersion.

[0026] Preferably, in step (2), the anti-yellowing functional additive includes one or more of Doverphos S-480, Doverphos S-680, Doverphos S-682, or Doverphos S-9228. The anti-yellowing agent exhibits excellent temperature resistance, does not degrade during the polyamide polymerization process, and can synergize with the end-capping agent to improve weather resistance. The anti-yellowing functional additive is purchased from Dover Chemicals, USA; Doverphos is a trade name.

[0027] Preferably, in step (2), the melt polycondensation includes a first heating and holding reaction, a second heating and holding reaction, and a polymerization reaction after decompression.

[0028] Preferably, in step (2), the single-stage heating and pressure holding reaction refers to heating to 200–220°C (more preferably 205–215°C) and maintaining the pressure inside the reactor at 1.8–2.2 MPa (more preferably 1.9–2.1 MPa) for 1.5–2.0 h. The single-stage heating and pressure holding process mainly involves the prepolymerization of components S1 and S2 to obtain oligomers.

[0029] Preferably, in step (2), the secondary heating and pressure holding reaction refers to: continuing to heat to 250-270℃ (more preferably 260-270℃), slowly releasing gas during the heating process to maintain the pressure inside the reactor at 1.6-2.0 MPa (more preferably 1.7-1.9 MPa), and reacting for 1.5-2.0 h. The secondary heating and pressure holding process mainly involves reducing the pressure inside the system while heating, slowly releasing gas to avoid excessive gas release rate or volume, which would prevent the temperature inside the system from reaching the target value.

[0030] Preferably, in step (2), the polymerization reaction after depressurization refers to: slowly releasing the gas until the pressure inside the reactor drops to normal pressure, draining the water from the system, and then gradually drawing a vacuum.

[0031] Preferably, the stepwise vacuuming refers to: first, vacuuming to -0.01 to -0.03 MPa (more preferably -0.02 to -0.03 MPa), then holding the pressure for 10 to 20 minutes (more preferably 15 to 20 minutes); then vacuuming to -0.03 to -0.05 MPa (more preferably -0.04 to -0.05 MPa), then holding the pressure for 10 to 20 minutes (more preferably 15 to 20 minutes); finally, vacuuming to -0.05 to -0.07 MPa (more preferably -0.06 to -0.07 MPa), then holding the pressure for 20 to 30 minutes (more preferably 20 to 25 minutes). The polymerization reaction after depressurization mainly involves removing water molecules through depressurization, promoting the reversible reaction in the forward direction.

[0032] Preferably, in step (2), before the melt polycondensation, the air in the reactor is replaced with inert gas 3 to 4 times, and then inert gas is introduced to 0.15 to 0.20 MPa.

[0033] Preferably, in step (2), after the melt polycondensation, an inert gas is introduced to 0.2-0.3 MPa (more preferably 0.25-0.30 MPa).

[0034] Preferably, in step (2), the inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium. The inert gas used in this invention is a high-purity gas with a purity ≥ 99.999%.

[0035] The technical solution adopted by the present invention to further solve its technical problem is as follows: the application of a bio-based transparent polyamide resin, wherein the bio-based transparent polyamide resin is used in the fields of automotive industry, electronic appliances, industrial machinery, medical devices, optical glasses or aerospace, where the requirements for temperature resistance, chemical resistance and weather resistance are stringent.

[0036] The beneficial effects of this invention are as follows: (1) The relative viscosity of the bio-based transparent polyamide resin of the present invention can be controlled at around 2.50, the tensile strength is as high as 94 MPa, the flexural strength is as high as 127 MPa, and the notched impact strength is as high as 10.2 kJ / m. 2 With a glass transition temperature as high as 116℃, an initial decomposition temperature as high as 403.9℃, a light transmittance as high as 93.8%, a water absorption rate as low as 0.5%, and a color difference change as low as 5.1NBS after aging, it is suitable for automotive, electronics, industrial machinery, medical devices, optical lenses or aerospace fields with stringent requirements for temperature resistance, chemical resistance and weather resistance. (2) The bio-based transparent polyamide resin of the present invention has diversified products and can flexibly adjust the copolymerization ratio of component S1 and component S2 to customize the production of polyamide resins with different heat resistance and transparency grades to meet the performance requirements of specific application sites. (3) The raw materials of the method of the present invention are renewable, the production process is simple, all stages from raw materials to finished products can be completed in one reactor equipment, and the expected viscosity requirements can be achieved without solid phase thickening. The production cycle is short, the energy consumption and cost are low, and it is suitable for industrial continuous production. Attached Figure Description

[0037] Figure 1 These are the infrared spectra of the bio-based transparent polyamide resins of Examples 1-3 of this invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0039] The Doverphos S-680 and Doverphos S-682 used in the embodiments of the present invention were purchased from Dover Chemical Company, USA; the inert gases used in the embodiments and comparative examples of the present invention were high-purity gases with a purity of ≥99.999%; the raw materials or chemical reagents used in the embodiments of the present invention, unless otherwise specified, were obtained through conventional commercial channels.

[0040] Example 1 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=4, b=4.

[0041] like Figure 1 As shown, 3300cm -1 The nearby absorption peak corresponds to the NH stretching vibration on the amide bond, 2850–2950 cm⁻¹ -1 The double peak at 1680 cm⁻¹ represents the CH stretching vibration on the methylene group. -1 and 1640cm -1 Corresponding to the C=O stretching vibration on the amide bond, 1540 cm⁻¹ -1 The presence of CN stretching vibrations on the amide bond and the absence of characteristic absorption peaks of polyamide salts indicate that a bio-based transparent polyamide resin has been successfully synthesized.

[0042] Example 1: Preparation method of a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 176.3g (2.0mol) bio-based butylene diamine to 224.3g of pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 865.0g of component S1; add 344.3g (2.0mol) 2,5-thiophene dicarboxylic acid and 176.3g (2.0mol) bio-based butylene diamine to 182.3g of pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 702.9g of component S2; (2) Take 865.0g of component S1, 702.9g of component S2 (the mass ratio of components S1 and S2 is 1:0.81), 3.1g of sodium hypophosphite (equivalent to 0.2% of the total mass of components S1 and S2), 3.1g of 4-amino-2,2,6,6-tetramethylpiperidine and 3.1g of Doverphos obtained in step (1). S-480 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 213℃ and the pressure inside the reactor was maintained at 2.0 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 270℃, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.8 MPa. After a second heating and pressure holding reaction for 1.5 h, gas was slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 20 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0043] Application Example 1 of a Bio-based Transparent Polyamide Resin Example 1 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, and medical devices, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0044] Example 2 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=5, b=5.

[0045] like Figure 1 As shown, 3300cm -1 The nearby absorption peak corresponds to the NH stretching vibration on the amide bond, 2850–2950 cm⁻¹ -1 The double peak at 1680 cm⁻¹ represents the CH stretching vibration on the methylene group. -1and 1640cm -1 Corresponding to the C=O stretching vibration on the amide bond, 1540 cm⁻¹ -1 The presence of CN stretching vibrations on the amide bond and the absence of characteristic absorption peaks of polyamide salts indicate that a bio-based transparent polyamide resin has been successfully synthesized.

[0046] Example 2: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 204.4g (2.0mol) bio-based pentanediamine to 234.1g pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 902.9g component S1; weigh 344.3g (2.0mol) 2,5-thiophene dicarboxylic acid and 204.4g (2.0mol) bio-based pentanediamine to 192.1g pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 740.8g component S2; (2) Take 902.9g of component S1, 740.8g of component S2 (the mass ratio of components S1 and S2 is 1:0.82), 3.3g of sodium hypophosphite (equivalent to 0.2% of the total mass of components S1 and S2), 3.3g of 4-amino-2,2,6,6-tetramethylpiperidine and 3.3g of Doverphos obtained in step (1). S-680 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor three times with high-purity nitrogen, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 208°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. After a second heating and pressure holding reaction for 1.5 h, gas was slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 20 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0047] Application Example 2 of a Bio-based Transparent Polyamide Resin Example 2 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, and medical devices, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0048] Example 3 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0049] like Figure 1 As shown, 3300cm -1 The nearby absorption peak corresponds to the NH stretching vibration on the amide bond, 2850–2950 cm⁻¹ -1 The double peak at 1680 cm⁻¹ represents the CH stretching vibration on the methylene group. -1 and 1640cm -1 Corresponding to the C=O stretching vibration on the amide bond, 1540 cm⁻¹ -1 The presence of CN stretching vibrations on the amide bond and the absence of characteristic absorption peaks of polyamide salts indicate that a bio-based transparent polyamide resin has been successfully synthesized.

[0050] Example 3: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 1092.2g of component S1; weigh 344.3g (2.0mol) 2,5-thiophene dicarboxylic acid and 344.6g (2.0mol) bio-based decanediamine to 241.2g of pure water (water / (diacid + diamine) = 35%), stir to form salt, and obtain 930.1g of component S2; (2) Take 1092.2g of component S1, 930.1g of component S2 (the mass ratio of components S1 and S2 is 1:0.85), 5.1g of potassium hypophosphite (equivalent to 0.25% of the total mass of components S1 and S2), 5.1g of 4-amino-2,2,6,6-tetramethylpiperidine and 5.1g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 20 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0051] Application Example 3 of a Bio-based Transparent Polyamide Resin Example 3 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, and medical devices, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0052] Example 4 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0053] Example 4: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1092.2g of component S1; add 305.9g (1.96mol) 2,5-furandicarboxylic acid and 344.6g (2.0mol) bio-based decanediamine to 227.7g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 878.2g of component S2; (2) Take 1092.2g of component S1, 878.2g of component S2 (the mass ratio of components S1 and S2 is 1:0.80), 4.9g of potassium hypophosphite (equivalent to 0.25% of the total mass of components S1 and S2), 4.9g of 4-hydroxy-2,2,6,6-tetramethylpiperidine and 4.9g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.03 MPa and held for 20 min, then evacuated to -0.05 MPa and held for 20 min, and finally evacuated to -0.07 MPa and held for 25 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0054] Application Example 4 of a Bio-based Transparent Polyamide Resin Example 4 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, and medical devices, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0055] Example 5 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0056] Example 5: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1092.2g of component S1; add 313.9g (1.96mol) tetrahydrofurandicarboxylic acid and 344.6g (2.0mol) bio-based decanediamine to 230.5g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 889.0g of component S2; (2) Take 1092.2g of component S1, 889.0g of component S2 (the mass ratio of components S1 and S2 is 1:0.81), 4.9g of potassium hypophosphite (equivalent to 0.25% of the total mass of components S1 and S2), 4.9g of 4-hydroxy-2,2,6,6-tetramethylpiperidine and 4.9g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.03 MPa and held for 20 min, then evacuated to -0.05 MPa and held for 20 min, and finally evacuated to -0.07 MPa and held for 25 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0057] Application Example 5 of a Bio-based Transparent Polyamide Resin Example 5 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, and medical devices, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0058] Example 6 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0059] Example 6: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1092.2g of component S1; add 475.6g (2.97mol) tetrahydrofurandicarboxylic acid and 516.9g (3.0mol) bio-based decanediamine to 347.4g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1339.9g of component S2; (2) Take 1092.2g of component S1, 1339.9g of component S2 (the mass ratio of components S1 and S2 is 1:1.23), 4.9g of potassium hypophosphite (equivalent to 0.20% of the total mass of components S1 and S2), 4.9g of 4-hydroxy-2,2,6,6-tetramethylpiperidine and 4.9g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.03 MPa and held for 20 min, then evacuated to -0.05 MPa and held for 20 min, and finally evacuated to -0.07 MPa and held for 25 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0060] Application Example 6 of a Bio-based Transparent Polyamide Resin Example 6 describes the application of bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, medical devices, optical lenses, and aerospace, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0061] Example 7 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0062] Example 7: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1092.2g of component S1; add 634.1g (3.96mol) tetrahydrofurandicarboxylic acid and 689.2g (4.0mol) bio-based decanediamine to 463.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1786.5g of component S2; (2) Take 1092.2g of component S1, 1786.5g of component S2 (the mass ratio of components S1 and S2 is 1:1.64), 4.9g of potassium hypophosphite (equivalent to 0.17% of the total mass of components S1 and S2), 4.9g of 4-hydroxy-2,2,6,6-tetramethylpiperidine and 4.9g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.03 MPa and held for 20 min, then evacuated to -0.05 MPa and held for 20 min, and finally evacuated to -0.07 MPa and held for 25 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0063] Application Example 7 of a Bio-based Transparent Polyamide Resin Example 7 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, medical devices, optical lenses, or aerospace, where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0064] Example 8 of a bio-based transparent polyamide resin Its general structural formula is: Where R1 is R2 is a=10, b=10.

[0065] Example 8: A method for preparing a bio-based transparent polyamide resin (1) Add 464.4g (2.0mol) 5-(1H-pyrazol-4-yl) isophthalic acid and 344.6g (2.0mol) bio-based decanediamine to 283.2g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 1092.2g of component S1; add 951.2g (5.94mol) tetrahydrofurandicarboxylic acid and 1033.9g (6.0mol) bio-based decanediamine to 694.8g of pure water (water / (diacid + diamine) = 35%), stir to form a salt, and obtain 2679.9g of component S2; (2) Take 1092.2g of component S1, 2679.9g of component S2 (the mass ratio of components S1 and S2 is 1:2.45), 4.9g of potassium hypophosphite (equivalent to 0.13% of the total mass of components S1 and S2), 4.9g of 4-hydroxy-2,2,6,6-tetramethylpiperidine and 4.9g of Doverphos obtained in step (1). S-682 was placed in a high-temperature and high-pressure reactor. After replacing the air in the reactor with high-purity nitrogen three times, high-purity nitrogen was introduced to 0.15 MPa for melt polycondensation: the temperature was first raised to 207°C and the pressure inside the reactor was maintained at 1.9 MPa for a first heating and pressure holding reaction for 2.0 h. The temperature was then raised to 268°C, and gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.7 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. Gas was then slowly released until the pressure inside the reactor dropped to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for depressurization and polymerization: the vacuum was first evacuated to -0.03 MPa and held for 20 min, then evacuated to -0.05 MPa and held for 20 min, and finally evacuated to -0.07 MPa and held for 25 min. High-purity nitrogen was then introduced to 0.3 MPa, and the material was discharged to obtain bio-based transparent polyamide resin.

[0066] Application Example 8 of a Bio-based Transparent Polyamide Resin Example 8 uses bio-based transparent polyamide resin in technical fields such as automotive, electronics, industrial machinery, medical devices, optical lenses, or aerospace where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

[0067] Comparative Example 1 (1) 1461.4g (10.0mol) adipic acid (molecular weight: 146.141g / mol) and 1021.8g (10.0mol) pentanediamine (molecular weight: 102.178g / mol) were added to 869.1g of pure water and stirred to form a salt, resulting in 3352.3g of polyamide 56 salt solution; (2) Add 13352.3g of polyamide 56 salt solution and 8.4g of sodium hypophosphite obtained in step (1) into the reactor. The subsequent operation is the same as step (2) of Example 2. Finally, polyamide 56 is obtained.

[0068] To evaluate the mechanical, heat resistance, optical, water absorption, and weather resistance properties of the bio-based transparent polyamide resins obtained in Examples 1-8 of the present invention and the polyamide 56 obtained in Comparative Example 1, tests were conducted under the following conditions: Relative viscosity: The sample was placed in a vacuum drying oven at 120℃ for 4 hours and a concentrated sulfuric acid solution with a concentration of 0.010 g / mL was prepared. The solution was tested using an automatic viscometer in accordance with the standard GB / T 38138-2019. Tensile strength: The tensile specimens were placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T1040.2-2006; Bending strength: The bending specimen was placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T9341-2008; Notched impact strength: The impact specimens were placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T1043.1-2008; Glass transition temperature: Weigh 5-10 mg of sample, heat the sample to 300℃ for 3 min under high-purity nitrogen protection, quench it with liquid nitrogen, then heat the quenched sample to 280℃, cool it to room temperature, and then heat it to 280℃ again. The heating rate is 10℃ / min, referring to standard GB / T 19466.3-2004. Initial decomposition temperature: Weigh 3-8 mg of sample, and under high-purity nitrogen protection, heat the sample to 700℃. The temperature at which the sample loses 5% of its weight is the initial decomposition temperature, referring to standard GB / T 33047.1-2016. Light transmittance: After injection molding into a standard sample and cutting, the light transmittance was tested in accordance with standard GB / T 2410-2008. Water absorption rate: The sample was dried in a 100℃ oven and cooled in the oven. The water absorption rate at 23℃ for 24h was tested according to ASTM D570-98 standard. Color difference (ΔE): The samples were aged using a xenon arc lamp aging test chamber for a total exposure time of 1000 hours, and the color change value was measured using a colorimeter. The test standard was GB / T 16422.3-2014. The results are shown in Table 1.

[0069]

[0070] As shown in Table 1, the relative viscosity of the bio-based transparent polyamide resins obtained in Examples 1-8 of this invention can be controlled at around 2.50, with a tensile strength as high as 94 MPa, a flexural strength as high as 127 MPa, and a notched impact strength as high as 10.2 kJ / m. 2 With a glass transition temperature as high as 116℃, an initial decomposition temperature as high as 403.9℃, a light transmittance as high as 93.8%, a water absorption rate as low as 0.5%, and a color difference change as low as 5.1 NBS after aging, the bio-based transparent polyamide resins of the present invention (Examples 1-8) exhibit excellent mechanical, optical, heat resistance, and weather resistance properties, making them suitable for applications in the automotive industry, electronics, industrial machinery, medical devices, optical lenses, and aerospace fields where stringent requirements for temperature resistance, chemical resistance, and weather resistance are necessary. Compared to polyamide 56 obtained in Comparative Example 1, the bio-based transparent polyamide resins of the present invention (Examples 1-8) demonstrate excellent heat and chemical resistance properties by introducing meta-benzene rings and five-membered heterocyclic structures into their molecular backbone. By introducing five-membered nitrogen heterocyclic structures such as pyrazole, triazole, tetraazole, and imidazole into their molecular side chains, the tight packing between chains is broken, resulting in excellent light transmittance and adhesion properties. Furthermore, the mechanical strength and water absorption properties are adjusted by introducing bio-based diamines with different carbon chain lengths.

Claims

1. A bio-based transparent polyamide resin, characterized in that, Its general structural formula is: Wherein, R1 is a meta-aromatic dicarboxylic acid group substituted with a nitrogen heterocyclic ring, R2 is a cyclic bio-based dicarboxylic acid group, and a or b = 4, 5, 6 or 10.

2. The bio-based transparent polyamide resin according to claim 1, characterized in that: The nitrogen-substituted meta-aromatic dicarboxylic acid group includes: , , , , or One or more of them; The cyclic bio-based dicarboxylic acid groups include: , or One or more of them.

3. A method for preparing the bio-based transparent polyamide resin as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Add the nitrogen-substituted meta-aromatic dicarboxylic acid and the bio-based diamine to pure water and stir to form a salt to obtain component S1; Cyclic bio-based dicarboxylic acid and bio-based diamine are added to pure water and stirred to form a salt, yielding component S2; (2) The components S1, S2, catalyst, end-capping agent and anti-yellowing functional additive obtained in step (1) are put into a high temperature and high pressure reactor. After replacing the air in the reactor with inert gas, inert gas is introduced and melt polycondensation is carried out. Then inert gas is introduced again and the material is discharged to obtain bio-based transparent polyamide resin.

4. The method for preparing the bio-based transparent polyamide resin according to claim 3, characterized in that: In step (1), in component S1, the molar ratio of the nitrogen-substituted meta-aromatic dicarboxylic acid to the bio-based diamine is 0.97 to 1.00:1; the amount of pure water used is equivalent to 30 to 40% of the total mass of the nitrogen-substituted meta-aromatic dicarboxylic acid and the bio-based diamine; the nitrogen-substituted meta-aromatic dicarboxylic acid includes one or more of 5-(1H-pyrazol-4-yl)isophthalic acid, 5-(1H-1,2,4-triazol-1-yl)isophthalic acid, 5-(1H-tetrazole-5-yl)isophthalic acid, 5-(1H-tetrazole-1-yl)isophthalic acid, 4,6-bis(1H-imidazol-1-yl)isophthalic acid or 4,6-bis(1H-1,2,4-triazol-1-yl)isophthalic acid; In component S2, the molar ratio of the cyclic bio-based dicarboxylic acid to the bio-based diamine is 0.97–1.00:1; the amount of pure water used is equivalent to 30–40% of the total mass of the cyclic bio-based dicarboxylic acid and the bio-based diamine; the cyclic bio-based dicarboxylic acid includes one or more of 2,5-thiophene dicarboxylic acid, 2,5-furan dicarboxylic acid, or tetrahydrofuran dicarboxylic acid; In components S1 and S2, the bio-based diamine includes one or more of bio-based butylene diamine, pentanediamine, hexanediamine, or decanediamine.

5. The method for preparing the bio-based transparent polyamide resin according to claim 3 or 4, characterized in that: In step (2), the mass ratio of component S1 to component S2 is 1:0.5 to 5.0; the amount of catalyst, end-capping agent, and anti-yellowing functional additive is 0.1 to 0.5% of the total mass of component S1 and component S2; the catalyst includes one or more of sodium hypophosphite, potassium hypophosphite, or magnesium hypophosphite; the end-capping agent includes one or more of 4-amino-2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, or bis(2,2,6,6-tetramethylpiperidine-4-yl)amine; the anti-yellowing functional additive includes one or more of Doverphos S-480, Doverphos S-680, Doverphos S-682, or Doverphos S-9228.

6. The method for preparing the bio-based transparent polyamide resin according to claim 3 or 4, characterized in that: In step (2), the melt polycondensation includes a first heating and pressure holding reaction, a second heating and pressure holding reaction, and a polymerization reaction after decompression. The first heating and pressure holding reaction refers to heating to 200-220°C and maintaining the pressure inside the reactor at 1.8-2.2 MPa for 1.5-2.0 h. The second heating and pressure holding reaction refers to continuing to heat to 250-270°C, slowly releasing gas during the heating process to maintain the pressure inside the reactor at 1.6-2.0 MPa for 1.5-2.0 h. The polymerization reaction after decompression refers to slowly releasing gas until the pressure inside the reactor drops to atmospheric pressure, draining the water from the system, and then gradually evacuating the system. The stepwise vacuuming process refers to: first, evacuating to -0.01 to -0.03 MPa, then maintaining the pressure for 10 to 20 minutes; then evacuating to -0.03 to -0.05 MPa, then maintaining the pressure for 10 to 20 minutes; finally, evacuating to -0.05 to -0.07 MPa, then maintaining the pressure for 20 to 30 minutes. Before the melt polycondensation, the air inside the reactor is replaced with inert gas 3 to 4 times, and then inert gas is introduced to 0.15 to 0.20 MPa. After the melt polycondensation, inert gas is introduced again to 0.2 to 0.3 MPa. The inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium.

7. The method for preparing the bio-based transparent polyamide resin according to claim 5, characterized in that: In step (2), the melt polycondensation includes a first heating and pressure holding reaction, a second heating and pressure holding reaction, and a polymerization reaction after decompression. The first heating and pressure holding reaction refers to heating to 200-220°C and maintaining the pressure inside the reactor at 1.8-2.2 MPa for 1.5-2.0 h. The second heating and pressure holding reaction refers to continuing to heat to 250-270°C, slowly releasing gas during the heating process to maintain the pressure inside the reactor at 1.6-2.0 MPa for 1.5-2.0 h. The polymerization reaction after decompression refers to slowly releasing gas until the pressure inside the reactor drops to atmospheric pressure, draining the water from the system, and then gradually evacuating the system. The stepwise vacuuming process refers to: first, evacuating to -0.01 to -0.03 MPa, then maintaining the pressure for 10 to 20 minutes; then evacuating to -0.03 to -0.05 MPa, then maintaining the pressure for 10 to 20 minutes; finally, evacuating to -0.05 to -0.07 MPa, then maintaining the pressure for 20 to 30 minutes. Before the melt polycondensation, the air inside the reactor is replaced with inert gas 3 to 4 times, and then inert gas is introduced to 0.15 to 0.20 MPa. After the melt polycondensation, inert gas is introduced again to 0.2 to 0.3 MPa. The inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium.

8. An application of the bio-based transparent polyamide resin as described in claim 1 or 2, characterized in that: The bio-based transparent polyamide resin described in claim 1 or 2 is used in the automotive, electronics, industrial machinery, medical device, optical lens, or aerospace technology fields where stringent requirements for temperature resistance, chemical resistance, and weather resistance are required.

Images