A bio-based copolyamide and methods of making and using the same

Abstract

The application relates to the fields of special polymer materials and green manufacturing technology, and discloses a bio-based copolymer polyamide, a macromolecular main chain of which is composed of randomly copolymerized terephthalamide structural units and furan dicarboxamide structural units; and a preparation method of the bio-based copolymer polyamide, which comprises the following steps: S1, salification and prepolymerization; long-chain aliphatic diamines and aromatic diacids are subjected to prepolymerization to prepare an oligomer; the aromatic diacids include terephthalic acid and 2,5-furan dicarboxylic acid; the proportion of the terephthalic acid is 50-90 mol% and the proportion of the 2,5-furan dicarboxylic acid is 10-50 mol% in the total 100 mol% of the aromatic diacids; S2, flash-out of the material; and S3, solid-phase tackifying polycondensation. The problems of high intrinsic density and close melting point and thermal degradation temperature of the existing PPA are solved.

Description

Technical Field

[0001] This invention relates to the field of special polymer materials and green manufacturing technology, specifically to a bio-based copolyamide, its preparation method, and its application. Background Technology

[0002] PPA is a general term for a class of semi-aromatic polyamides made from terephthalic acid (PTA) or isophthalic acid (IPA), including various types such as PA6T, PA9T, and PA10T. Because its main chain contains a large number of rigid benzene rings, it exhibits excellent heat resistance, low water absorption, and superior mechanical properties, thus enjoying wide applications. For example, PA10T can be processed into various products through injection molding and extrusion, such as LED reflector brackets, connectors, consumer electronics components, and automotive parts.

[0003] Existing commercially available PPA faces two major technical bottlenecks: First, the intrinsic density of the material is too high. The symmetrical benzene ring structure of PTA leads to extremely tight and orderly packing of macromolecular chains in the crystalline region, resulting in a resin density typically around 1.20 g / cm³. 3 The material's dimensions are limited, making it difficult to meet the extreme lightweight requirements of aerospace and new energy vehicles for components. Secondly, its processing temperature window is extremely narrow. The highly symmetrical structure endows the material with extremely high crystallinity and a high melting point (T). m Typically between 315℃ and 330℃, this temperature is very close to the severe thermal degradation temperature of polyamide (T0). d In actual injection molding, the material is extremely prone to thermal and oxidative aging, discoloration and yellowing, and performance degradation, making processing extremely difficult.

[0004] To lower the melting point, existing technologies typically employ copolymerization of long-chain aliphatic diacids (such as adipic acid), but this sacrifices the material's long-term heat resistance (i.e., T). g The glass transition temperature and rigidity come at a huge cost. Therefore, developing a new type of PPA that can reduce density and widen the melt processing window without sacrificing the long-term heat resistance of the material is an urgent problem to be solved in the field of specialty engineering plastics. Summary of the Invention

[0005] The present invention aims to provide a bio-based copolyamide, its preparation method and application, in order to solve the problems of high intrinsic density and melting point and thermal degradation temperature of existing PPA.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a bio-based copolyamide, the structure of which is a compound as shown in formula (1) and its racemic, stereoisomer, or tautomer: (1) In formula (1): m is 9 or 10, x+y=19~21, and k is 3~4. Among them, x and y are the degree of polymerization of terephthalamide structural units and furanyl dicarboxamide structural units in the copolymer oligomer, respectively, and k is the chain extension degree of the oligomer in the copolymer polymer.

[0007] By randomly copolymerizing terephthalamide and furanyl dicarboxamide structural units to form polymers, bio-based copolymer polyamides possess the advantages of low intrinsic density and low melting point, achieving lightweighting and widening the window between melting point and thermal degradation temperature. This effectively solves the problem of high intrinsic density and close melting point and thermal degradation temperature in existing PPAs.

[0008] Preferably, the intrinsic density of the bio-based copolyamide is 1.11~1.18 g / cm³. 3 Its melting point is 280~295℃, and its glass transition temperature is greater than 150℃.

[0009] The beneficial effects of this plan are: (1) Breaking the regularity of packing to achieve intrinsic lightweighting: By partially replacing traditional terephthalic acid with bio-based FDCA, the “micro-bent” five-membered ring conformation of FDCA effectively hinders the excessive tightness between molecular chains, forcibly increases the free volume of the amorphous region, and then cleverly utilizes its nonlinear asymmetric structure to break the crystal regularity to achieve intrinsic lightweighting.

[0010] (2) The temperature window for processing is greatly widened: The introduction of asymmetric furan rings as "lattice defects" disrupts the original highly regular molecular chain arrangement of the resin, forming structural defects and reducing the degree of crystallization and crystallization stability. This is reflected in the macroscopic thermal properties as the material melting point steadily decreases. Compared with PA10T, the melting point of the material steadily decreases from above 315℃ to 280~295℃, completely moving away from the thermal degradation red line of polyamide (380~420℃), thereby significantly reducing processing energy consumption and greatly reducing the yellowing phenomenon of PPA resin during the molding process.

[0011] (3) Maintaining high thermal stability: Unlike fatty acid modification, FDCA remains a highly rigid aromatic heterocyclic ring. Introducing it into the main chain does not significantly reduce the overall rigidity of the molecular chain, nor does it significantly increase the flexibility of the molecular chain. Therefore, the segmental mobility of its macromolecular chain at high temperatures is not greatly improved, thus maintaining the glass transition temperature (Tg) of PPA resin. g The high thermal stability of the bio-based copolyamide is maintained at a high level, ensuring the dimensional stability and mechanical retention of the material under high temperature conditions.

[0012] (4) Naturally enhanced interfacial bonding strength: Compared with existing PPA resins, the interfacial bonding strength of this bio-based copolyamide is naturally enhanced. This is due to the strong polarity of oxygen atoms on the furan ring, which can significantly enhance the hydrogen bond interaction between PPA and the surface of glass fiber or carbon fiber. Excellent mechanical properties of composite materials can be obtained without the need to add compatibilizers.

[0013] This invention also provides a method for preparing a bio-based copolyamide, comprising the following steps: S1, Salt formation and prepolymerization: Oligomers are prepared by prepolymerization of long-chain aliphatic diamines and aromatic dicarboxylic acids. S2, flash evaporation discharge, the oligomer is cooled and solidified by flash evaporation to obtain prepolymer powder; S3, solid-phase thickening polycondensation, involves heating the prepolymer powder to obtain a bio-based copolyamide.

[0014] The beneficial effects of this scheme are: by adding a furan ring, the regularity of the molecular chain can be disrupted to reasonably lower the melting point and widen the processing window, while the rigidity of the aromatic heterocyclic ring can maintain a high melting point (T). g This method achieves both high-temperature dimensional stability and intrinsic lightweighting, as well as improved interfacial bonding. Furthermore, thanks to the lower melting point and improved melt flowability resulting from the copolymer structure, this method can more effectively remove small-molecule byproducts (water) in the later stages of the polycondensation reaction, thereby significantly increasing the degree of polymerization while avoiding thermal degradation.

[0015] Preferably, the long-chain aliphatic diamine in S1 is selected from at least one of 1,9-nonanediamine or 1,10-decanediamine; the aromatic dicarboxylic acid is selected from terephthalic acid and 2,5-furandicarboxylic acid, with terephthalic acid accounting for 50-90 mol% and 2,5-furandicarboxylic acid accounting for 100 mol% of the total molar amount of aromatic dicarboxylic acids.

[0016] The beneficial effects of this scheme are as follows: by controlling the ratio of terephthalic acid to 2,5-furandicarboxylic acid at 50~90 mol%:10~50 mol%, the regularity of the molecular chain is moderately disrupted to reasonably reduce the melting point and broaden the processing window. This avoids the deterioration of crystallization and mechanical properties caused by insufficient modification effect due to too low furan ring content or too high content, so that the material achieves the optimal balance in terms of processability, heat resistance, lightweight and mechanical properties.

[0017] Preferably, the prepolymerization in S1 is completed in an aqueous system, and the prepolymerization process also includes the addition of a catalyst and a capping agent.

[0018] Preferably, the capping agent is selected from benzoic acid or acetic acid, and the molar amount of the capping agent is 0.5~2.0 mol of the total molar amount of the aromatic dicarboxylic acid.

[0019] Preferably, the catalyst is selected from hypophosphite.

[0020] Preferably, the catalyst is selected from sodium hypophosphite.

[0021] Preferably, in S1, the temperature of the prepolymerization reaction is 220~250℃, the pressure is 1.5~2.5MPa, and the time is 1~2h.

[0022] The beneficial effects of this method are as follows: Compared with existing traditional resin synthesis processes, the mild reaction conditions in this step reduce random chain scission reactions, resulting in a narrower molecular weight distribution (PDI) and more uniform and stable material mechanical properties. Furthermore, the lower synthesis temperature reduces oxidation and yellowing, resulting in lower initial particle color and meeting appearance requirements without the need for large amounts of whitening agents.

[0023] Preferably, in S2, during the process of depressurizing the high-pressure system after the S1 reaction and performing flash evaporation, the moisture is vaporized and removed, and the oligomers are simultaneously cooled, crystallized, and pulverized into prepolymer powder.

[0024] Preferably, in step S3, the heat treatment temperature is 240~260℃ and the time is 4~8h; the heat treatment is carried out in a vacuum or inert atmosphere.

[0025] The beneficial effects of this solution are: the low-temperature SSP process greatly inhibits thermal oxidative degradation, and the tackified resin still maintains a low yellowing index and excellent mechanical toughness, avoiding the material embrittlement problem caused by traditional high-temperature tackification.

[0026] The present invention also provides an application of a bio-based copolyamide, wherein the bio-based copolyamide is used in injection-molded or extruded electronic component bases, high-temperature resistant components around automotive engines, or lightweight structural components for aircraft.

[0027] The beneficial effects of this solution are as follows: Although the melting point of the bio-based copolyamide is reduced, it still remains in the high-temperature range above 280°C, which fully meets the requirements of lead-free reflow soldering (260°C) and long-term heat resistance in automotive engine compartments (150°C+), achieving the best balance between processability and heat resistance; the lower processing temperature reduces the requirements for the high-temperature resistance of the screw and barrel, extends the equipment life, and reduces production energy consumption. Attached Figure Description

[0028] Figure 1 This is a flow chart of the preparation process of bio-based copolyamide in this invention. Detailed Implementation

[0029] The implementation of the present invention will now be described with reference to preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0030] In this invention, the macromolecular backbone of the bio-based copolyamide is composed of random copolymerization of terephthalamide structural units and furanyl dicarboxamide structural units, and its general structural formula is shown in formula (1): (1) In formula (1), m is 9 or 10, x and y are the degrees of polymerization of terephthalamide and furanyl dimethylamide structural units in the copolymer oligomer, respectively, x+y=19~21, and k is the chain extension degree of the oligomer in the copolymer polymer, k is 3~4. In the reaction, the polyamide includes three cases: m=9, m=10, and diamine monomers containing m=9 and m=10 are polymerized.

[0031] The specific steps for preparing the above-mentioned bio-based copolyamide are as follows: S1, Salt formation and prepolymerization. Long-chain aliphatic diamines are prepolymerized with a mixture of aromatic diacids to prepare oligomers.

[0032] Long-chain aliphatic diamines include any one or both of 1,9-nonanediamine and 1,10-decanediamine; mixed aromatic dicarboxylic acids include PTA (terephthalic acid) and FDCA (2,5-furandicarboxylic acid, i.e., fructose-derived bio-based).

[0033] The prepolymerization reaction is carried out in an aqueous system. Long-chain aliphatic diamines, PTA, FDCA, catalysts, and end-capping agents are added to deionized water and placed in a high-pressure reactor. The high temperature and self-generated steam pressure within the reactor complete the primary amidation ring-opening and oligomerization reactions. The catalyst is hypophosphite, and the end-capping agent is benzoic acid or acetic acid, with the molar amount of end-capping agent being 0.5–2.0 mol% of the total molar amount of aromatic dicarboxylic acids. The reaction temperature within the sealed high-pressure reactor is controlled at 220–250 °C, the pressure at 1.5–2.5 MPa, and the reaction time at 1–2 h to obtain an oligomer melt containing water.

[0034] The reaction equation in this step is shown in equation (2). This stage utilizes aqueous salt formation to avoid the prepolymerization reaction carried out at extremely high temperatures, effectively preventing the early thermal degradation of the furan ring.

[0035] (2) In formula (2), m is 9 or 10, x and y are the degree of polymerization of terephthalamide structural units and furan dicarboxamide structural units in the copolymer oligomer, respectively, x+y=19~21, and k is the chain extension degree of the oligomer in the copolymer polymer, k is 3~4.

[0036] S2, flash evaporation discharge: the oligomer melt obtained in the previous step is rapidly cooled and solidified by flash evaporation, and then broken into prepolymer powder with a large specific surface area.

[0037] Stable discharge is achieved by slowly opening the discharge valve, allowing the high-pressure oligomer melt to be continuously injected into the atmospheric pressure flash tank under the system pressure difference. Flash evaporation is achieved using this instantaneous pressure difference. During flash evaporation, moisture is rapidly vaporized and removed, while the oligomer melt simultaneously cools, crystallizes, and is pulverized into white prepolymer powder. Flash evaporation instantly removes a large amount of moisture from the reaction system in gaseous form, utilizing the latent heat of water vaporization to rapidly cool and solidify the oligomer, and breaking the melt into high specific surface area prepolymer powder. This method features high dehydration efficiency and rapid cooling, further preventing thermal degradation of the material and facilitating subsequent solid-phase polycondensation.

[0038] S3, solid-phase condensation polymerization (SSP), involves heating the prepolymer powder to induce a condensation reaction, ultimately yielding a semi-aromatic bio-based copolyamide product.

[0039] The prepolymer powder obtained in S2 is transferred to a rotary vacuum dryer or solid-state reactor. Under the protection of ultra-high vacuum or high-purity nitrogen gas flow, it is heated to 240~260℃ and then reacted at a constant temperature for 4~8h to promote the prepolymer end groups to continue to condense and expel small molecule water in the solid state, thereby obtaining the target PPA resin with high molecular weight, namely bio-based copolyamide; the reaction equation in this step is shown in equation (3).

[0040] (3) In equation (3), m is 9 or 10, x and y are the degrees of polymerization of the terephthalamide structural unit and the furanyl dicarboxamide structural unit in the copolymer oligomer, respectively, x+y=19~21, and k is the chain extension degree of the oligomer in the copolymer polymer, k is 3~4. In SSP, the introduction of the furan ring improves the microscopic freeness of the molecular chain, so the end groups can still maintain sufficient collision probability in the solid state; through a solid-state dehydration polycondensation reaction lasting several hours, the molecular weight of the prepolymer is increased to the engineering grade standard that can be used for injection molding or extrusion.

[0041] The preparation method of this bio-based copolyamide starts with the innovative selection of raw materials. By partially replacing traditional terephthalic acid with bio-based FDCA, its nonlinear asymmetric structure is cleverly utilized to break the crystal regularity and achieve intrinsic lightweighting. The "micro-bent" five-membered ring conformation of FDCA effectively prevents excessive tight bonding between molecular chains, forcibly increasing the free volume of the amorphous region. The intrinsic density of the final bio-based copolyamide, measured according to ISO 1183 standard, shows that compared with pure PA10T, its intrinsic density can be reduced from 1.19 g / cm³. 3 Decreased to 1.11~1.18 g / cm³ 3 .

[0042] Meanwhile, the processing temperature window of bio-based copolyamides has also been significantly broadened. The introduction of asymmetric furan rings, acting as "lattice defects," disrupts the originally highly ordered molecular chain arrangement of PA10T, forming structural defects and reducing crystallinity and stability. This is reflected in the macroscopic thermal properties as a steady decrease in the material's melting point. Compared to PA10T, the melting point of the material steadily decreases from above 315℃ to 280~295℃, completely moving away from the thermal degradation red line of polyamides (380~420℃), thereby significantly reducing processing energy consumption and greatly reducing the yellowing phenomenon of PPA resin during molding.

[0043] Furthermore, unlike fatty acid modification, FDCA remains a highly rigid aromatic heterocyclic compound. Introducing it into the main chain does not significantly reduce the overall rigidity of the molecular chain, nor does it significantly increase its flexibility. Therefore, the segmental mobility of its macromolecular chain at high temperatures is not substantially improved, thus affecting the glass transition temperature (Tg) of PPA resin. g The levels remained high. The bio-based copolyamide obtained in S3 was subjected to thermal performance testing (DSC). Specifically, differential scanning calorimetry (DSC) was used, with two heating and cooling cycles performed at a heating rate of 10 °C / min. The temperature (T) was read from the second heating curve. m and T g Thermal performance tests showed that copolymerization not only failed to soften the main chain, but actually increased the material's thermal conductivity (T). g The temperature is kept stable between 150 and 165°C, ensuring the dimensional stability and mechanical retention of the material under high temperature conditions, that is, the bio-based copolyamide maintains high thermal stability.

[0044] Finally, compared with existing PPA resins, this bio-based copolyamide naturally exhibits enhanced interfacial bonding strength. This is due to the strong polarity of oxygen atoms on the furan ring, which significantly enhances the hydrogen bond interaction between PPA and the surface of glass or carbon fibers, allowing for the acquisition of excellent composite material mechanical properties without the need for additional compatibilizers.

[0045] The properties of this bio-based copolyamide are further explained below with reference to examples and comparative examples.

[0046] Example 1: 30% FDCA modified PA10T copolyamide A method for preparing 30% FDCA modified PA10T copolyamide, the specific steps of which are as follows: S101, salt formation and prepolymerization.

[0047] 1500g of deionized water was added to a 5L stainless steel high-pressure reactor, followed by 440.0g of 1,10-decanediamine (2.55mol, including 2% end-capping and volatility compensation), 290.7g (1.75mol) of PTA, 117.1g of FDCA (0.75mol), 0.8g of sodium hypophosphite (catalyst), and 3.0g of benzoic acid (end-capping agent). After purging the reactor with high-purity nitrogen three times, the reactor was sealed and heated to 230℃, reaching a self-generated pressure of 2.2MPa. Under this constant temperature and pressure, the reaction was stirred for 2 hours to form an oligomer melt.

[0048] The reaction equation in step S101 is shown in equation (4): (4) In equation (4): m is 9, x is 14, y is 6, and k is 3.5.

[0049] S102, flash evaporation discharge.

[0050] The discharge valve at the bottom of the reactor is connected to a flash tank equipped with a cyclone separator. The discharge valve is slowly opened, and the high-pressure oligomer melt is injected into the atmospheric-pressure flash tank under pressure differential. Moisture vaporizes instantly, and the oligomer rapidly cools, crystallizes, and is pulverized into a white prepolymer powder. The prepolymer powder is collected and dried in a vacuum oven. After drying, the intrinsic viscosity of the prepolymer powder is tested. Specifically, at 25°C, concentrated sulfuric acid (98%) is used as the solvent, and the intrinsic viscosity of the sample is measured using an Ubbelohde viscometer to characterize the molecular weight of the polymer. In this example, the intrinsic viscosity of the prepolymer powder was measured to be 0.45 dL / g. After thickening, the intrinsic viscosity reaches 1.15 dL / g, indicating that it fully meets the requirements for injection molding.

[0051] S103, solid-phase viscosity-enhancing polycondensation (SSP).

[0052] The prepolymer powder was transferred to a double-cone rotary vacuum dryer, and under continuous tumbling and high vacuum (<100 Pa) conditions, the temperature was slowly increased to 250°C (reaction temperature 250°C) at a rate of 2°C / min. The solid-phase thickening reaction is carried out at a constant temperature of about 35°C below the expected melting point of the prepolymer powder for 6 hours; then the temperature is lowered to below 80°C and discharged to obtain high molecular weight lightweight bio-based copolyamide powder (i.e., 30% FDCA modified PA10T copolyamide powder); or the obtained powder is granulated by single screw extrusion to obtain granular products.

[0053] The reaction equations for S102 and S103 are shown in equation (5): (5) In equation (5), m is 9, x is 14, and y is 6.

[0054] The structural formula of the high molecular weight, lightweight bio-based copolyamide powder is shown in formula (6): (6) In equation (6), m is 9, x is 14, y is 6, and k is 3.5.

[0055] Finally, the performance of the bio-based copolyamide obtained in this embodiment was tested, and the test results are shown in Table 1: The intrinsic density is 1.140 g / cm³. 3 It has a significantly lower intrinsic density than the traditional PA10T, which is 1.19 g / cm³. 3 .

[0056] Thermal performance test results: T m Temperature dropped sharply to 288℃; T g It still reaches a high of 153℃.

[0057] After thickening, the intrinsic viscosity is 1.15 dL / g, which fully meets the requirements for injection molding.

[0058] Processability evaluation: When injection molded at 305℃, the melt flowed smoothly, and the injection molded sample showed a bright original color without obvious yellowing.

[0059] Example 2: 15% FDCA lightly modified PA10T copolyamide (balanced formulation) A method for preparing 15% FDCA lightly modified PA10T copolyamide, the specific steps of which are as follows: S201, salt formation and prepolymerization.

[0060] The ratio of aromatic dicarboxylic acid was adjusted to 353.0 g (2.125 mol) PTA and 58.5 g (0.375 mol) FDCA; and the high-pressure prepolymerization temperature in the sealed reactor was adjusted to 240 °C. The dosage and steps of 1,10-decanediamine and other auxiliaries were the same as in S101 of Example 1.

[0061] The reaction equation in step S201 is shown in equation (7): (7) In equation (7): m is 9, x is 17, y is 3, and k is 3.5.

[0062] S202, flash evaporation discharge.

[0063] The flash evaporation output is the same as S102 in Example 1.

[0064] S203, solid-phase viscosity-enhancing polycondensation (SSP).

[0065] In this step, due to the high symmetry of the aromatic rings, the expected melting point of the material is higher. Therefore, the isothermal reaction temperature of SSP was adjusted to 265°C, and the reaction time under high vacuum was adjusted to 5 hours; the remaining processes are the same as S103 in Example 1.

[0066] The reaction equations for S202 and S203 are shown in equation (8): (8) In equation (8), m is 9, x is 17, y is 3, and k is 3.5.

[0067] The structural formula of the high molecular weight, lightweight bio-based copolyamide powder is shown in formula (9): (9) In equation (9), m is 9, x is 17, y is 3, and k is 3.5.

[0068] Finally, the performance of the bio-based copolyamide obtained in this embodiment was tested, and the test results are shown in Table 1: The intrinsic density is 1.168 g / cm³. 3 Its intrinsic density is 1.19 g / cm³ lower than that of the traditional PA10T. 3 .

[0069] Thermal performance test results: T m Temperature dropped to 302℃ (an improvement over the 315℃ of pure PA10T); T g It reaches as high as 156℃.

[0070] The intrinsic viscosity after thickening is 1.18 dL / g.

[0071] Processability evaluation: The processing window has been slightly widened, making it suitable for applications requiring higher resistance to high temperature and impact.

[0072] Example 3: 50% FDCA heavily modified PA10T copolyamide (upper limit verification) A method for preparing 50% FDCA heavily modified PA10T copolyamide, the specific steps of which are as follows: S301, salt formation and prepolymerization.

[0073] The ratio of aromatic dicarboxylic acid was adjusted to 207.7 g (1.25 mol) PTA and 195.1 g (1.25 mol) FDCA; and the high-pressure prepolymerization temperature in the sealed reactor was adjusted to 220 °C to protect the high concentration of furan rings. The dosage and steps of 1,10-decanediamine and other auxiliaries were the same as in S101 of Example 1.

[0074] The reaction equation in step S301 is shown in equation (10): (10) In equation (10): m is 9, x is 10, y is 10, and k is 3.5.

[0075] S302, flash evaporation discharge.

[0076] The flash evaporation output is the same as S102 in Example 1.

[0077] S303, solid-phase viscosity-enhancing polycondensation (SSP).

[0078] The isothermal reaction temperature of SSP was adjusted to 240°C, and everything else was the same as S103 in Example 1.

[0079] The reaction equations for S302 and S303 are shown in equation (11): (11) In equation (11), m is 9, x is 10, y is 10, and k is 3.5.

[0080] The structural formula of the high molecular weight, lightweight bio-based copolyamide powder is shown in formula (12): (12) In equation (12), m is 9, x is 10, y is 10, and k is 3.5.

[0081] Finally, the performance of the bio-based copolyamide obtained in this embodiment was tested, and the test results are shown in Table 1: The intrinsic density is 1.115 g / cm³. 3 .

[0082] Thermal performance test results: T m Dropped to 281℃; T g Maintain at 150℃.

[0083] The intrinsic viscosity after thickening is 1.12 dL / g.

[0084] Processability evaluation: The material exhibits excellent lightweight properties and extremely low processing temperature, which meets the scope of the claims of this invention.

[0085] Comparative Example 1: Synthesis of pure PA10T (0% FDCA benchmark comparison) The preparation method of PA10T is as follows: S1001, salt formation and prepolymerization.

[0086] In this embodiment, 415.3g (2.5mol) of PTA was used as the sole dicarboxylic acid component, and no FDCA was added. The dosage of other raw materials and additives, as well as the process, were the same as in S101 of Example 1.

[0087] S1002, flash evaporation discharge.

[0088] The flash evaporation output is the same as S102 in Example 1.

[0089] S1003, solid-phase viscosity-enhancing polycondensation (SSP).

[0090] Because the prepolymer has an extremely high melting point, the isothermal reaction temperature of SSP was adjusted to 280°C; the rest of the process was the same as S103 in Example 1.

[0091] Finally, the performance of the PA10T obtained in this comparative example was tested, and the test results are shown in Table 1: The intrinsic density is 1.195 g / cm³. 3 It exhibits typical high-density characteristics.

[0092] Thermal performance test results: T m Up to 316℃; T g The temperature is 158℃.

[0093] The intrinsic viscosity after thickening is 1.15 dL / g.

[0094] Processability evaluation: The injection molding machine needs to be heated to 330~340℃ to obtain good melt flowability; at this temperature, some resin undergoes thermal degradation, and the edges of the injection molded samples show yellowing and brittleness (the processing window is extremely narrow).

[0095] Comparative Example 2: PA10T copolyamide modified with 60% FDCA excess (upper limit exceeded) A method for preparing 60% FDCA heavily modified PA10T copolyamide, the specific steps of which are as follows: S2001, salt formation and prepolymerization.

[0096] The ratio of aromatic dicarboxylic acid was adjusted to 166.1 g (1.0 mol) PTA and 234.2 g (1.5 mol) FDCA, so that the FDCA content was 60%. The dosage of other raw materials and additives, as well as the process, were the same as in S301 of Example 3.

[0097] S2002, flash evaporation discharge.

[0098] The flash evaporation output is the same as S302 in Example 3.

[0099] S2003, solid-phase viscosity-enhancing polycondensation (SSP).

[0100] Solid-phase thickening polycondensation is the same as S303 in Example 3.

[0101] Finally, the performance of the resin powder obtained in this comparative example was tested, and the test results are shown in Table 1.

[0102] Because of the introduction of too many asymmetric furan rings, the crystallinity regularity of the molecular chain was completely destroyed, T m When FDCA disappears or drops to extremely low levels, the material tends towards an amorphous state. Furthermore, excessively high concentrations of FDCA lead to the thermal degradation and ring-opening of the furan ring during the solid-phase thickening stage of SSP, resulting in a resin powder with a distinctly yellowish-brown color and an intrinsic viscosity of only 0.65 dL / g, which fails to meet the mechanical and aesthetic requirements of engineering plastics. Comparative Example 2 demonstrates that controlling the upper limit of FDCA to 50% is absolutely necessary.

[0103] Comparative Example 3: 5% FDCA ultra-low content modified PA10T copolyamide (lower limit exceeded) A method for preparing 5% FDCA ultra-low content modified PA10T copolyamide, the specific steps of which are as follows: S3001, salt formation and prepolymerization.

[0104] The ratio of aromatic dicarboxylic acid was adjusted to 394.5g (2.375mol) PTA and 19.5g (0.125mol) FDCA, i.e., PTA accounted for 95mol% and FDCA accounted for 5mol%; and the high-pressure prepolymerization temperature in the sealed reactor was adjusted to 240℃, and the dosage of 1,10-decanediamine and other additives was the same as S101 in Example 1.

[0105] S3002, flash evaporation discharge.

[0106] The flash evaporation output is the same as S102 in Example 1.

[0107] S3003, solid-phase viscosity-enhancing polycondensation (SSP).

[0108] The isothermal reaction temperature of SSP was adjusted to 275°C, and everything else was the same as S103 in Example 1.

[0109] Finally, the performance of the resin powder obtained in this comparative example was tested, and the test results are shown in Table 1: The intrinsic density is 1.185 g / cm³. 3 .

[0110] Thermal performance test results: T m Up to 312℃; T g The temperature is 157℃.

[0111] The intrinsic viscosity after thickening is 1.14 dL / g.

[0112] Processability evaluation: The temperature needs to be raised to above 325℃ during injection molding. The material is prone to thermal degradation and yellowing, which proves that a small amount (5%) of asymmetric furan rings is insufficient to effectively disrupt the regular stacking of macromolecular chains.

[0113] Comparative Example 4: 15% FDCA modified PA10T copolyamide (prepolymerization temperature decreased compared to Example 2) A method for preparing 15% FDCA modified PA10T copolyamide, the specific steps of which are as follows: S4001, salt formation and prepolymerization.

[0114] In this embodiment, the high-pressure prepolymerization temperature is set to 230°C, which is lower than 240°C in Example 2; the ratio of aromatic dicarboxylic acid and the dosage and process of other additives are the same as S201 in Example 2.

[0115] S4002, flash evaporation discharge.

[0116] The flash evaporation output is the same as S202 in Example 2.

[0117] S4003, solid-phase viscosity-enhancing polycondensation (SSP).

[0118] SSP is the same as S302 in Example 3.

[0119] Finally, the performance of the bio-based copolyamide powder obtained in this comparative example was tested, and the test results are shown in Table 1.

[0120] After approximately 1.5 hours of salt formation and prepolymerization, the stirring torque in the reactor increased dramatically. During flash evaporation, a large amount of oligomers agglomerated at the bottom of the reactor, making discharge extremely difficult. The collected small amount of powder, after SSP treatment, had an intrinsic viscosity of only 0.62 dL / g. This demonstrates that the prepolymerization temperature of this invention requires a dynamic inverse matching with the FDCA content: when the FDCA ratio is low and the system has strong crystallinity, lowering the prepolymerization temperature is insufficient to maintain the molten state of the oligomers in the aqueous phase, leading to early precipitation; conversely, when the FDCA ratio is high (as in Example 3), a lower prepolymerization temperature must be used to prevent the thermal degradation of the furan ring. This dynamic matching mechanism is key to balancing stable discharge and preventing discoloration.

[0121] Table 1: Process and Performance Parameters of Bio-based Copolyamides As shown in Table 1, when the FDCA content is 0% (i.e., pure PA10T), the intrinsic density of the polymer is 1.195 g / cm³. 3 As the FDCA content increased to 30% (Example 1) and 50% (Example 3), the density decreased to 1.14 g / cm³. 3 1.115g / cm 3 This indicates that the addition of FDCA can reduce the intrinsic density of the polymer; however, when the FDCA content is as high as 60% (Comparative Example 2), the polymer exhibits an amorphous state and lacks a stable structure.

[0122] When the FDCA content is 0%, the polymer's T m At 316°C; when the content is 15% (Example 2), polymer T m The melting point of the polymer was 302℃; when the content was 50%, the polymer melting point dropped to 281℃, indicating that the higher the FDCA content, the lower the polymer melting point.

[0123] Glass transition temperature (T) g The overall fluctuation was relatively small, remaining within the 150-158℃ range, indicating that the addition of FDCA had a positive effect on the polymer's T... g The impact is not significant.

[0124] At the same FDCA content (15%), Example 2 (polymerization 240℃, SSP 265℃) showed stable performance, while Comparative Example 4 (polymerization 230℃, SSP 240℃) showed agglomeration, indicating that too low a reaction temperature will lead to the deterioration of polymer processing performance.

[0125] When the FDCA content is 5% (Comparative Example 3), the polymer density is 1.185 g / cm³. 3 The temperature Tm is 312℃, which is close to that of Comparative Example 1 with 0% content, indicating that when modifying polymers with FDCA, it is necessary to ensure that the content of FDCA reaches a certain proportion in order to achieve effective improvement.

[0126] Injection Molding Application and Heat Resistance Verification of Electronic SMT Connectors To further verify the wide processing window and high heat resistance of the bio-based copolyamide provided by this invention, this embodiment provides a method for resin injection molding and heat resistance performance verification, the specific steps of which are as follows: S401, Sample parts are prepared by injection molding based on resin raw materials.

[0127] The bio-based copolyamide resin (30% FDCA) prepared in Example 1 and the pure PA10T resin (0% FDCA) prepared in Comparative Example 1 were respectively blended with 30 wt% glass fiber and extruded to injection mold a precision electronic connector base for printed circuit boards (PCBs), i.e., a sample part.

[0128] S402, each sample part is tested.

[0129] The tests include injection molding yield and reflow soldering heat resistance tests.

[0130] When conducting injection molding yield testing, evaluate the color stability and short-filling situation during 1000 consecutive injection molding cycles.

[0131] During the reflow soldering heat resistance test, the SMT surface mount process was simulated. The sample part, namely the electronic SMT connector base obtained in S401, was passed through a reflow oven with a maximum temperature of 260℃ and a duration of 10s. The dimensional deformation and blistering were observed.

[0132] S403, Test Result Analysis.

[0133] The test results are as follows: Injection molding yield: Polymer in Example 1 due to T m When the temperature is reduced to 288℃, the injection molding machine temperature can be set to 305℃ for smooth mold filling. After 1000 injection molding cycles, the product color is white and stable, with a yield rate of 99.8%. In contrast, the injection temperature of pure PA10T resin in Comparative Example 1 is as high as 335℃, and carbonized black spots are easily generated in the barrel, resulting in a higher defect rate.

[0134] Reflow soldering heat resistance test: Although the polymer in Example 1 had a lower melting point, its T... g The temperature remained as high as 153°C. After reflow soldering at 260°C, the sample did not exhibit any blistering, melting, or significant dimensional shrinkage deformation (dimensional change rate <0.1%), and fully passed the SMT process certification.

[0135] Test data proves that the lightweight, high-heat-resistant bio-based copolyamide resin synthesized in Example 1 successfully solved the fatal problem of traditional high-temperature nylon being extremely prone to thermal degradation by widening the processing window, and exhibited perfect dimensional stability in subsequent extreme high-temperature processing (SMT reflow soldering).

[0136] In summary, this invention not only provides a high-performance PPA resin material, but also represents a novel strategy for resolving the inherent contradictions between "heat resistance and processing" and "high strength and lightweight" in engineering plastics from the perspective of molecular conformation design. By cleverly introducing bio-based furan ring units with unique spatial configurations, the invention successfully breaks through the densification and high melting point barriers caused by the highly ordered crystallization of traditional semi-aromatic polyamides, constructing a novel topological structure at the molecular scale that combines moderate free volume with a rigid framework. This structural innovation not only endows the material with intrinsic lightweight and excellent dimensional stability, but also fundamentally broadens the processing window, freeing the material from dependence on extreme high-temperature processing and significantly enhancing its potential for green manufacturing. Crucially, the inherent polarity of the furan ring naturally strengthens the interfacial interaction between the matrix and reinforcing fibers, breaking through the path dependence of traditional composite materials on compatibilizers. Therefore, the material system constructed in this invention achieves a leap from single-performance optimization to multi-dimensional synergistic performance of "lightweight, easy to process, high heat resistance, and strong interface," providing a highly forward-looking technological paradigm for next-generation green, low-carbon, and high-performance engineering structural materials.

[0137] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A bio-based copolyamide, characterized in that, Compounds with structures as shown in formula (1) and their racemates, stereoisomers, or tautomers: （1） In formula (1): m is 9 or 10, x+y=19~21, and k is 3~4.

2. The bio-based copolyamide according to claim 1, characterized in that, The intrinsic density of the bio-based copolyamide is 1.11~1.18 g / cm³. 3 Its melting point is 280~295℃, and its glass transition temperature is greater than 150℃.

3. A method for preparing a bio-based copolyamide, characterized in that, Includes the following steps: S1, Salt formation and prepolymerization: Oligomers are prepared by prepolymerization of long-chain aliphatic diamines and aromatic dicarboxylic acids. S2, flash evaporation discharge, the oligomer is cooled and solidified by flash evaporation to obtain prepolymer powder; S3, solid-phase thickening polycondensation, involves heating the prepolymer powder to obtain a bio-based copolyamide.

4. The method for preparing the bio-based copolyamide according to claim 3, characterized in that, The long-chain aliphatic diamine in S1 is selected from at least one of 1,9-nonanediamine and 1,10-decanediamine; the aromatic dicarboxylic acid is selected from terephthalic acid and 2,5-furandicarboxylic acid, with terephthalic acid accounting for 50-90 mol% and 2,5-furandicarboxylic acid accounting for 100 mol% of the total molar amount of aromatic dicarboxylic acids.

5. The method for preparing bio-based copolyamide according to claim 3, characterized in that, The prepolymerization in S1 is completed in an aqueous system, and the prepolymerization process also includes the addition of a catalyst and a capping agent.

6. The method for preparing bio-based copolyamide according to claim 5, characterized in that, The capping agent is selected from benzoic acid or acetic acid, and the molar amount of the capping agent is 0.5~2.0 mol of the total molar amount of the aromatic dicarboxylic acid.

7. The method for preparing bio-based copolyamide according to claim 3, characterized in that, In S1, the temperature of the prepolymerization reaction is 220~250℃, the pressure is 1.5~2.5MPa, and the time is 1~2h.

8. The method for preparing bio-based copolyamide according to claim 7, characterized in that, In S2, the high-pressure system after the S1 reaction is depressurized and flash evaporated, the moisture is removed by vaporization, and the oligomers are simultaneously cooled, crystallized, and crushed into prepolymer powder.

9. The method for preparing bio-based copolyamide according to claim 3, characterized in that, In S3, the heat treatment temperature is 240~260℃ and the time is 4~8h; the heat treatment is carried out in a vacuum or inert atmosphere.

10. An application of a bio-based copolyamide, characterized in that, The bio-based copolyamide is used in injection-molded or extruded electronic component bases, high-temperature resistant components around automotive engines, or lightweight structural components for aircraft.

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