A polyamide 66 resin, its preparation method and use

Abstract

This invention belongs to the field of polyamides, specifically relating to a high-viscosity polyamide 66 resin, its preparation method, and its applications. The high-viscosity polyamide 66 resin of this invention has a relative viscosity of 3.0~6.5 and a terminal amine content ≤50mmol / kg. The method for preparing the high-viscosity polyamide 66 resin of this invention is carried out under positive pressure conditions, using a nitrogen atmosphere, and the temperature is always kept below the melting point of polyamide 66. This not only ensures uniform heating of the material but also prevents air from entering and causing yellowing. Downstream products prepared using the high-viscosity polyamide 66 resin of this invention possess excellent properties such as high impact resistance, high shear resistance, high toughness, and low-temperature toughness that meets application requirements.

Description

[0001] This application is a divisional application of the patent application filed on December 16, 2024, with application number 202411852328.6 and invention title "A polyamide 66 resin and its preparation method and application". Technical Field

[0002] This invention belongs to the field of polyamide 66 resin, specifically relating to a polyamide 66 resin, its preparation method, and its application. Background Technology

[0003] Nylon materials are widely used in aerospace, military, machinery, and automotive industries due to their low density, wear resistance, fatigue resistance, good chemical stability, high temperature resistance, and a combination of rigidity and toughness. Polyamide 66 (PA66, polyhexamethylene adipamide) is one of the most widely used nylon materials. It is produced by the condensation polymerization of hexamethylenediamine and adipic acid. It has advantages such as high strength, corrosion resistance, fatigue resistance, impact resistance, friction resistance, and flexibility and ease of processing. Therefore, it is widely used in clothing, decoration, tire carcass materials, conveyor belt canvas, cables, lifting slings, and other fields.

[0004] Domestically produced PA66 resin is mainly low-viscosity and medium-viscosity products with low molecular weight. In certain specific environments, such as prolonged low-temperature conditions, environments with frequent temperature changes, or environments subjected to long-term impact, its stability is poor, making it prone to brittle fracture and cracking, resulting in performance and service life that fail to meet expectations. In terms of processing, low-viscosity and medium-viscosity products have a higher melt flow rate. When directly used in extruded products (sheets, pipes), this can cause melt dripping or casting, making molding difficult and limiting its application range.

[0005] High-viscosity PA66 resin has a high degree of polymerization and a large relative molecular mass. In terms of usability, its mechanical properties, chemical stability, dimensional stability, chemical resistance, and fatigue resistance are all superior to ordinary PA66. It can be used to manufacture injection molded parts subjected to long-term cyclic stress, clothing yarns, airbag yarns, and ultra-fine denier fibers, offering broad market potential and development prospects. In terms of processability, high-viscosity PA66 has high melt strength and a low melt flow rate. When used directly in extruded products, it is less prone to melt dripping or casting, thus compensating for and expanding the application areas of PA66 resin.

[0006] Meanwhile, conventional PA66 production methods, whether melt polymerization or salt-forming polymerization, ultimately result in the melt being transferred out of the reactor. When the product viscosity is high, the high melt viscosity and slow flow rate reduce production efficiency. Furthermore, the prolonged residence time of the melt under high-temperature conditions in the reactor increases the likelihood of various side reactions and byproducts, affecting product quality. Increasing the melt flow rate by increasing the reactor pressure would require pressures far exceeding those used in conventional production, posing certain safety hazards. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention proposes a high-viscosity polyamide 66 resin with a relative viscosity of 3.0 to 6.5 and its preparation method. Furthermore, it can be combined with different functional components to form compositions for use in injection molded parts, films, and fiber industries, depending on the application requirements.

[0008] Specifically, one aspect of the present invention provides a high-viscosity polyamide 66 resin, wherein the high-viscosity polyamide 66 resin has a relative viscosity of 3.0 to 6.5 and a terminal amino content of ≤50 mmol / kg.

[0009] In one or more embodiments, the high-viscosity polyamide 66 resin has a relative viscosity of 3.2 to 6.5 and a terminal amine content of ≤32 mmol / kg.

[0010] In one or more embodiments, the high-viscosity polyamide 66 resin has a relative viscosity of 4.0 to 6.5 and a terminal amine content of ≤18 mmol / kg.

[0011] In one or more embodiments, the terminal amine content of the high-viscosity polyamide 66 resin is ≥1 mmol / kg, for example ≥2 mmol / kg or ≥3 mmol / kg.

[0012] Another aspect of the present invention provides a method for preparing the high-viscosity polyamide 66 resin according to any embodiment of the present invention, the method comprising: subjecting a medium- or low-viscosity polyamide 66 resin to a solid-state polycondensation reaction to obtain the high-viscosity polyamide 66 resin.

[0013] In one or more embodiments, the medium-low viscosity polyamide 66 resin has a relative viscosity ≥2.2 and <3.0, and a terminal amine content of 20~80 mmol / kg.

[0014] In one or more embodiments, the method includes the following steps:

[0015] Medium- and low-viscosity polyamide 66 resin is introduced into a solid-phase polycondensation reactor. The gas in the solid-phase polycondensation reactor is replaced with nitrogen. The temperature of the solid-phase polycondensation reactor is raised to 150°C to 260°C, preferably 160°C to 240°C, and maintained for 0.5 to 30 hours, preferably 2 to 24 hours. Then the temperature is lowered to 20 to 70°C, preferably 30 to 60°C, before the material is discharged.

[0016] In one or more embodiments, the method employs method A, method B, method C, or method D throughout the entire process from heating to cooling to maintain the pressure inside the reactor higher than the external atmospheric pressure, i.e., gauge pressure > 0 kPa.

[0017] Method A: Continuously add nitrogen and continuously vent the gas, preferably making the gauge pressure 10~100kPa;

[0018] Method B: Continuously introduce nitrogen gas and intermittently vent it. For example, vent the gas when the gauge pressure reaches 15~100kPa, and stop venting when the gauge pressure reaches 0~15kPa (excluding 0kPa). Wait for the gauge pressure to rise back to 15~100kPa before venting again. Repeat this operation.

[0019] Method C: Intermittently introduce nitrogen gas and continuously vent it. For example, when the gauge pressure is 0~15kPa (excluding 0kPa), introduce nitrogen gas to 15~100kPa. When the gauge pressure slowly drops to 0~15kPa (excluding 0kPa), repeat the nitrogen gas introduction operation.

[0020] Method D: Intermittently introduce nitrogen and intermittently exhaust it. For example, introduce nitrogen until the gauge pressure is 15~100kPa, and after a period of time, exhaust the gas until the gauge pressure is 0~15kPa (excluding 0kPa). Then immediately introduce nitrogen until the gauge pressure is 15~100kPa, and repeat the operation. The interval time is preferably 5~30min.

[0021] Another aspect of the present invention provides a polyamide 66 resin composition comprising component I and component II, wherein component I is the high-viscosity polyamide 66 resin described in any embodiment of the present invention, and component II is an additive.

[0022] In one or more embodiments, the additive is selected from one or more of heat stabilizers, UV absorbers, lubricants, nucleating agents, plasticizers, and colorants.

[0023] In one or more embodiments, component I accounts for 60% to 99.99% of the mass fraction of the polyamide 66 resin composition, for example 65%, 70%, 75%, 80%, 85%, 90%, 95%.

[0024] In one or more embodiments, component I accounts for 90% to 99.99% of the mass fraction of the polyamide 66 resin composition.

[0025] In one or more embodiments, component I accounts for 95% to 99.99% of the mass fraction of the polyamide 66 resin composition.

[0026] In one or more embodiments, component II accounts for 0.01% to 40% by mass of the polyamide 66 resin composition, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0027] In one or more embodiments, component II accounts for 0.01% to 10% of the mass fraction of the polyamide 66 resin composition.

[0028] In one or more embodiments, component II accounts for 0.01% to 5% by mass of the polyamide 66 resin composition.

[0029] In one or more embodiments, the heat stabilizer is an antioxidant selected from one or more of hindered phenolic heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, copper / cuprous salt heat stabilizers, phosphate / phosphite heat stabilizers, and aniline heat stabilizers.

[0030] In one or more embodiments, the lubricant is a dispersant selected from one or more of long-chain carboxylic acids and their salts or esters, silicone resins, and ethylene bis-stearamide graft copolymers.

[0031] Another aspect of the present invention provides a polyamide 66 resin composition comprising a main material and an additive masterbatch, wherein the main material is the high-viscosity polyamide 66 resin described in any embodiment of the present invention, and the additive masterbatch comprises a base material and additives, wherein the base material is selected from one or more of polyamide 6 (polycaprolactam), polyamide 66 and polyamide MXD6 (poly(m-phenylene adipamide), and the additives are preferably selected from one or more of heat stabilizers, UV absorbers, lubricants, nucleating agents and plasticizers.

[0032] In one or more embodiments, the main ingredient accounts for 60% to 99.99% of the mass fraction of the polyamide 66 resin composition, for example, 65%, 70%, 75%, 80%, 85%, 90%, 95%.

[0033] In one or more embodiments, the main ingredient accounts for 90% to 99.9% of the mass fraction of the polyamide 66 resin composition.

[0034] In one or more embodiments, the main ingredient accounts for 95% to 99.99% of the mass fraction of the polyamide 66 resin composition.

[0035] In one or more embodiments, the additive masterbatch accounts for 0.01% to 40% of the mass fraction of the polyamide 66 resin composition, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0036] In one or more embodiments, the additive masterbatch accounts for 0.01% to 10% of the mass fraction of the polyamide 66 resin composition.

[0037] In one or more embodiments, the additive masterbatch accounts for 0.01% to 5% of the mass fraction of the polyamide 66 resin composition.

[0038] In one or more embodiments, the relative viscosity of the base material is 2.0 to 4.0.

[0039] In one or more embodiments, the relative viscosity of the base material is 2.3 to 3.9.

[0040] In one or more embodiments, the relative viscosity of the base material is 2.7 to 3.9.

[0041] In one or more embodiments, the total mass of the additive masterbatch is 1000 parts, wherein the additive masterbatch contains 700-999 parts of the base material, 1-150 parts of the heat stabilizer, 0-10 parts of the UV absorber, 0-200 parts of the lubricant, 0-100 parts of the nucleating agent, and 0-100 parts of the plasticizer.

[0042] In one or more embodiments, the total mass of the additive masterbatch is 1000 parts, wherein the additive masterbatch contains 750-950 parts of the base material, 40-120 parts of the heat stabilizer, 0-5 parts of the UV absorber, 10-100 parts of the lubricant, 0-20 parts of the nucleating agent, and 0-30 parts of the plasticizer.

[0043] Another aspect of the invention provides the use of the high-viscosity polyamide 66 resin or the polyamide 66 resin composition described in any embodiment of the invention in the preparation of injection molded parts, films or filaments.

[0044] Another aspect of the present invention provides injection molded parts, films or filaments prepared using the high-viscosity polyamide 66 resin or the polyamide 66 resin composition described in any embodiment of the present invention.

[0045] In one or more embodiments, the injection molded part is a railway gauge baffle seat or a railway pre-embedded sleeve.

[0046] In one or more embodiments, the thread is brush filament or palm filament.

[0047] This invention provides a high-viscosity polyamide 66 resin with a relative viscosity reaching up to 6.5. Based on this high-viscosity polyamide 66 resin, this invention provides a series of flexibly formulated polyamide 66 resin compositions, enabling a faster and more targeted response to downstream application needs. Simultaneously, this invention provides a method for preparing polyamide 66 resin. This method is simple, effective, and more targeted, with low equipment requirements, allowing the chemical reaction to occur more uniformly on the material. It also reduces the thermal history and degree of heating of the material reaction, thereby reducing side reactions, and minimizes the possibility of yellowing of the material and product through positive pressure reaction. Downstream products prepared using the polyamide 66 resin of this invention possess excellent properties such as high impact resistance, high shear resistance, high toughness, and low-temperature toughness that meets application requirements. Detailed Implementation

[0048] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0049] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0050] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0051] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0052] Unless otherwise specified, percentage refers to mass percentage, proportion refers to mass ratio, and part refers to mass part.

[0053] In this article, the sum of the percentages of all components in the composition is 100%.

[0054] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by this invention.

[0055] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0056] In this article, "viscosity" refers to the relative viscosity value measured by the sulfuric acid method; all pressure values ​​mentioned are "gauge pressure", that is, the pressure difference between the pressure value and the atmospheric pressure outside the reactor.

[0057] The relative viscosity of the high-viscosity polyamide 66 resin of the present invention is 3.0 to 6.5, for example 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, preferably 3.2 to 6.5, and more preferably 4.0 to 6.5.

[0058] The high-viscosity polyamide 66 resin of the present invention has a terminal amino content of ≤50 mmol / kg, for example 1 mmol / kg, 2 mmol / kg, 3 mmol / kg, 5 mmol / kg, 10 mmol / kg, 15 mmol / kg, 20 mmol / kg, 25 mmol / kg, 30 mmol / kg, 35 mmol / kg, 40 mmol / kg, 41 mmol / kg, 42 mmol / kg, 43 mmol / kg, 44 mmol / kg, 45 mmol / kg, 46 mmol / kg, 47 mmol / kg, 48 mmol / kg, 49 mmol / kg, preferably ≤32 mmol / kg, and more preferably ≤18 mmol / kg.

[0059] The preparation methods of the high-viscosity polyamide 66 resin of the present invention include, but are not limited to: direct melt polymerization of hexamethylenediamine and adipic acid; polymerization of hexamethylenediamine and adipic acid after a salt-forming reaction and necessary post-treatment, followed by polymerization of the intermediate product nylon salt; further condensation polymerization of medium- and low-viscosity polyamide 66 in melt state via continuous processing or secondary processing using a screw extruder; and solid-phase polycondensation of medium- and low-viscosity polyamide 66. Preferably, the high-viscosity polyamide 66 resin of the present invention is obtained by solid-phase polycondensation of medium- and low-viscosity polyamide 66.

[0060] In this invention, medium-low viscosity polyamide 66 resin refers to polyamide 66 resin with a relative viscosity of 2.2 to 3.0 (excluding 3.0). The relative viscosity of medium-low viscosity polyamide 66 resin can be 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, or 2.9. The terminal amine content of medium-low viscosity polyamide 66 resin can be 20 to 80 mmol / kg, for example, 25 mmol / kg, 30 mmol / kg, 35 mmol / kg, 40 mmol / kg, 45 mmol / kg, 50 mmol / kg, 55 mmol / kg, 60 mmol / kg, 65 mmol / kg, 70 mmol / kg, or 75 mmol / kg.

[0061] In this invention, the selection of the raw material resin formulation affects the relative viscosity and terminal amino number of the prepared high-viscosity polyamide 66 resin. Therefore, the relative viscosity and terminal amino number of the high-viscosity polyamide 66 resin prepared in this invention do not follow a single linear change.

[0062] The high-viscosity polyamide 66 resin of the present invention can be obtained by the following solid-state polycondensation reaction:

[0063] Medium-to-low viscosity polyamide 66 resin is introduced into a solid-phase polycondensation reactor. The gas in the solid-phase polycondensation reactor is replaced with nitrogen gas, and the temperature of the solid-phase polycondensation reactor is raised to 150℃~260℃, for example 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, or 250℃, preferably 160℃~240℃; this temperature is maintained for 0.5~30 hours, for example 0.6 hours. The time for discharge is 0.7h, 0.8h, 0.9h, 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, preferably 2~24h; then the temperature is lowered to 20~70℃ for discharge, for example 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, preferably 30~60℃.

[0064] In this invention, the preferred temperature for the solid-state polycondensation reaction is 150℃ to 260℃. If the temperature is too high, there is a risk of approaching the melting point; simultaneously, higher temperatures result in a faster reaction rate, which is detrimental to production stability and repeatability. If the temperature is too low, the reaction rate is too slow, leading to low production efficiency. Therefore, controlling the equilibrium temperature of the reaction within the above range is beneficial for obtaining the high-viscosity polyamide 66 resin of this invention.

[0065] In this invention, the isothermal maintenance time for the solid-state polycondensation reaction is preferably 0.5 to 30 hours. If the equilibrium time is too short, the operating window is too narrow, which easily increases the risk of misoperation; if the equilibrium time is too long, it will lead to high energy consumption and low production efficiency. Therefore, controlling the equilibrium time of the reaction within the above range is beneficial to obtaining the high-viscosity polyamide 66 resin of this invention more efficiently.

[0066] In this invention, the higher the equilibrium temperature, the faster the reaction rate, and the higher the viscosity of the polyamide 66 resin product obtained within the same equilibrium time. Conversely, at a constant equilibrium temperature, the longer the equilibrium time, the higher the viscosity of the resulting polyamide 66 resin product. Therefore, a suitable equilibrium temperature and equilibrium time can be selected based on the relative viscosity of the target polyamide 66 resin and the ideal production time.

[0067] In this invention, the discharge temperature is preferably 20~70℃. If the discharge temperature is set too high, the material is prone to yellowing when it comes into contact with oxygen in the air during operation; if the discharge temperature is set too low, a longer cooling time is required, which will increase the corresponding energy consumption, labor and time costs.

[0068] In a preferred embodiment, the solid-phase polycondensation reaction of the present invention is carried out in a nitrogen atmosphere. Throughout the entire process from heating to cooling, the pressure inside the reactor is made higher than the external atmospheric pressure, i.e., gauge pressure > 0 kPa, using method A, method B, method C, or method D.

[0069] Method A: Nitrogen gas is added while excess gas is discharged. This method allows the nitrogen gas to carry away the water byproduct produced in the reaction. In this case, the gauge pressure of the reactor is preferably maintained at 10~100kPa, for example, 15kPa, 20kPa, 25kPa, 30kPa, 35kPa, 40kPa, 45kPa, 50kPa, 55kPa, 60kPa, 65kPa, 70kPa, 75kPa, 80kPa, 85kPa, 90kPa, and 95kPa.

[0070] Method B: Continuously introduce nitrogen to increase pressure, and intermittently ventilate. Method B can be to continuously introduce nitrogen, and when the pressure reaches 15-100 kPa, such as 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, when excess gas is vented, the vent valve is closed. Wait for the pressure inside the vessel to rise back to 0-15 kPa (excluding 0 kPa), such as 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, when venting is done again, and this operation is repeated.

[0071] Method C: Intermittent nitrogen gas is introduced, and continuous venting is performed. Method C can be implemented by introducing nitrogen gas to a pressure of 15-100 kPa when the pressure is between 0 and 15 kPa (excluding 0 kPa), such as 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, up to 15-100 kPa, such as 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 5 kPa. Repeat the nitrogen gas introduction process at pressures of 5 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, and 95 kPa, until the pressure slowly decreases to 0-15 kPa (excluding 0 kPa), for example, 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, and 14 kPa.

[0072] Method D: Intermittent ventilation and exhaust. Method D can involve introducing nitrogen gas to a pressure of 15~100 kPa, such as 16 kPa, 18 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, or 95 kPa, maintaining this pressure for a period of time, then exhausting the gas to a pressure of 0~15 kPa (excluding 0 kPa), such as 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, or 14 kPa, and immediately introducing fresh nitrogen gas to a gauge pressure of 15~100 kPa. This process is repeated. The duration of nitrogen gas introduction can be 5-30 minutes, for example, 5 minutes, 10 minutes, 20 minutes, or 30 minutes.

[0073] When preparing polyamide 66 resin using the solid-phase polycondensation method of the present invention, the gas pressure of the reaction system can be maintained in any of the above-mentioned ways according to the reactor conditions.

[0074] The solid-state polycondensation method of the present invention is preferably carried out under relatively low positive pressure conditions, using a nitrogen atmosphere, and the temperature is always below the melting point of polyamide 66. Using the method described herein not only ensures uniform heating of the material but also prevents air from entering and causing yellowing.

[0075] In some embodiments, the polyamide 66 resin composition of the present invention comprises component I and component II, wherein component I is the high-viscosity polyamide 66 resin in any embodiment of the present invention, and component II is an additive. The polyamide 66 resin composition of the present invention can be prepared by the following method: preparing high-viscosity polyamide 66 resin, and before discharge, mixing the additive with a small amount of polyamide 66 resin using a melt pump, mixing with the high-viscosity polyamide 66 resin during discharge, and jointly molding, cooling, and granulating. This also reduces modification and secondary processing. Although the high-viscosity polyamide 66 resin melt has poor fluidity and is difficult to discharge, this can be improved by pressurization, and equipment meeting the pressure requirements exists to satisfy the above process.

[0076] In some preferred embodiments, the additives included in the polyamide 66 resin composition of the present invention are one or more of the following: heat stabilizer, UV absorber, lubricant, nucleating agent, plasticizer and colorant.

[0077] Heat stabilizers can be antioxidants. Suitable antioxidants include, but are not limited to, one or more of hindered phenolic heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, copper / cuprous salt heat stabilizers, phosphate / phosphite heat stabilizers, and aniline heat stabilizers, such as additives with brand names 1098, 1010, 1330, Nylostab seed, Addworks TFB117, TAD, 944, 106, 626, 627, 9228, H318, H320, H321, H325, H326, H3336, H3338, H10, H3311, FLEXAME, and OKAFLEX EM.

[0078] Ultraviolet light absorbers include, but are not limited to, ultraviolet light absorbers with grades such as 326, 234, 1164, and VSU.

[0079] The lubricant can be a dispersant. Possible dispersants include, but are not limited to, long-chain carboxylic acids and their salts or esters, silicone resins, ethylene bis-stearamide graft copolymers, such as palmitic acid, lignite, sodium stearate, calcium stearate, aluminum stearate, pentaerythritol stearate, polysiloxane powder, TAF, TAF-A, and rice bran wax.

[0080] Nucleating agents include, but are not limited to, talc, silica, phthalate whiskers, magnesium oxide, aluminum oxide, zinc oxide, organophosphorus sodium, acetate, and commercial products with the designation P22 or CaV102.

[0081] Plasticizers include, but are not limited to, N-butyl-o-toluenesulfonamide and p-toluenesulfonamide.

[0082] Colorants include, but are not limited to, inorganic pigments, organic pigments and their masterbatches.

[0083] In this invention, component I can account for 60% to 99.99% of the mass fraction of the polyamide 66 resin composition, for example, 65%, 70%, 75%, 80%, 85%, 90%, 95%; component II can account for 0.01% to 40% of the mass fraction of the polyamide 66 resin composition, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0084] In some preferred embodiments, component I accounts for 90% to 99.99% of the polyamide 66 resin composition by mass, for example 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.95%, preferably 95% to 99.99%; component II accounts for 0.01% to 10% of the polyamide 66 resin composition by mass, for example 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, preferably 0.01% to 5%.

[0085] In this article, additives have multiple functions and are not limited to being used as a single type of additive. For example, sodium stearate can also act as a nucleating agent, but it is not limited to being used only as a lubricant.

[0086] In this article, the base material of the additive masterbatch can be polyamide 66 resin, polyamide 6 resin, or polyamide MXD6 resin with a relative viscosity of 2.0 to 4.0, preferably polyamide 66 resin. The relative viscosity of the base material can be 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, or 3.9, preferably 2.3 to 3.9, and more preferably 2.7 to 3.9.

[0087] In this document, the main material refers to the high-viscosity polyamide 66 resin in any of the embodiments described herein.

[0088] In this article, the additive can be added to the reactor and sintered onto the surface of polyamide 66 resin particles during solid-phase polycondensation; alternatively, a certain proportion of additive can be mixed with the base material to form a functional masterbatch, which is then mixed into high-viscosity polyamide 66 resin particles. This method offers greater flexibility in meeting downstream demands, allowing the functional masterbatch to be mixed into high-viscosity polyamide 66 resin products of varying viscosities according to requirements. It is particularly suitable for injection molded products because it can be mixed evenly in the screw section of the injection molding machine during the injection molding process, avoiding secondary melting and granulation of the material due to additive modification, simplifying the process flow, and reducing side reactions caused by secondary melting.

[0089] The additives used in this paper are preferably added to the resin composition by mixing them into the additive masterbatch.

[0090] In some embodiments, the polyamide 66 resin composition includes a base material and an additive masterbatch.

[0091] In this invention, the main material accounts for 60% to 99.99% of the mass fraction of the polyamide 66 resin composition, for example, 65%, 70%, 75%, 80%, 85%, 90%, and 95%; the additive masterbatch accounts for 0.01% to 40% of the mass fraction of the polyamide 66 resin composition, for example, 5%, 10%, 15%, 20%, 25%, 30%, and 35%.

[0092] In some preferred embodiments, the main material accounts for 90% to 99.99% of the mass fraction of the polyamide 66 resin composition, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.95%, preferably 95% to 99.99%; the additive masterbatch accounts for 0.01% to 10% of the mass fraction of the polyamide 66 resin composition, for example, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, preferably 0.01% to 5%.

[0093] While high-viscosity polyamide 66 resin offers superior mechanical and performance properties, it typically suffers from poor flowability, impacting processing efficiency. When functional masterbatches are combined with high-viscosity polyamide 66 resin, the low-viscosity polyamide component in the masterbatch's base material acts as a flux and flow aid, improving processing performance. Since the product's properties are primarily determined by the high-viscosity polyamide 66 resin, the low-viscosity polyamide component in the masterbatch base material does not affect product performance but does improve processing efficiency.

[0094] Injection molded parts prepared from high-viscosity polyamide 66 resin or polyamide 66 resin compositions in any of the embodiments described herein, after testing, meet the application requirements in flexural tests, shear properties, residual deformation, room temperature impact, low temperature impact, and fatigue tests, while similar products made from low-viscosity polyamide 66 resin do not meet the requirements.

[0095] The products provided herein include, but are not limited to, polyamide 66 resin compositions, their functional masterbatches, and downstream products such as injection molded parts. These products preferably do not contain polymers other than polyamides, and the additive content is preferably no more than 10%, more preferably no more than 5%. This better preserves the performance characteristics of polyamide 66, thereby maintaining the possibility of applications in more downstream fields. The high-viscosity polyamide 66 resin and polyamide 66 resin compositions of the present invention can be used not only for injection molded parts but also for spinning processing and related downstream applications, while controlling raw material costs.

[0096] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art, unless otherwise stated. The compounds in the embodiments are all commercially available.

[0097] In this invention, pressure refers to gauge pressure, which is the difference between the pressure inside the reactor and atmospheric pressure.

[0098] In this invention, viscosity refers to the relative viscosity of the polymer solution measured by the sulfuric acid method. The viscosity test method is as follows: the high-viscosity polyamide 66 resin of this invention is dissolved in 96wt% sulfuric acid as solvent, and a sample solution with a polymer concentration of 0.01±0.00001g / mL is prepared at 25°C for testing. Specific operation details refer to standard GB / T 12006.1-2009 (ISO 307:2007).

[0099] In this invention, the method for testing the number of terminal amino groups (i.e., the content of terminal amino groups) is as follows:

[0100] (1) Preparation of standard solution: Dilute 500ml of 0.05mol / L hydrochloric acid standard solution to 2500ml of 0.01mol / L hydrochloric acid solution;

[0101] (2) Standardization of standard solution: Refer to the standard method of GB / T 601-2016, weigh 0.2g of sodium carbonate after being ignited at 300℃, dissolve it in 50ml of pure water, and use the hydrochloric acid solution prepared in step (1) to titrate the sodium carbonate solution. Use a potentiometric titrator to determine the titration endpoint; refer to the standard GB / T 601-2016 for the calculation method of hydrochloric acid solution concentration.

[0102] (3) Terminal amino test

[0103] Referring to GB / T 38138-2019, the method for determining the terminal amino group of nylon, weigh approximately 1.0 g of the test particles into a glass sample bottle and record its accurate mass (accurate to 0.001 g); add 30 mL of hexafluoroisopropanol solution, tighten the cap and seal it with sealing film; let it stand for 1 day to dissolve, then vortex it to mix evenly, and then use the prepared hydrochloric acid solution to test the terminal amino group value of the test solution by potentiometric titration. The calculation method for the terminal amino group value refers to GB / T 601-2016 standard.

[0104] In the embodiments and comparative examples of the present invention, the low and medium viscosity polyamide 66 with different viscosities and terminal amino numbers were all purchased from Ningxia Ruitai Technology Co., Ltd. or its affiliates.

[0105] Example 1

[0106] Low-viscosity polyamide 66 resin with a viscosity of 2.35 and a terminal amine number of 42 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 100 kPa (gauge pressure). The temperature was then raised from 20°C to 180°C and maintained at 180°C for 14 hours, followed by cooling to 50°C for discharge. From the start of heating, the gas inside the reactor was vented every 10 minutes until the gauge pressure reached 10 kPa, and then nitrogen was immediately introduced until 100 kPa was reached. This process was repeated until cooling was complete. Excess gas was then released from the reactor to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 3.98 and a terminal amine number of 1 mmol / kg.

[0107] Example 2

[0108] Low-viscosity polyamide 66 resin with a viscosity of 2.43 and a terminal amino group number of 30 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the reactor pressure reached 90 kPa (gauge pressure). The temperature was then raised from 25°C to 170°C and maintained at 170°C for 12 hours, followed by cooling to 50°C for discharge. From the start of heating, the gas inside the reactor was vented every 10 minutes until the gauge pressure reached 10 kPa, and then nitrogen was immediately introduced to 90 kPa. This process was repeated until cooling was complete. Excess gas was then released from the reactor to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 3.14 and a terminal amino group number of 2 mmol / kg.

[0109] Example 3

[0110] Medium-viscosity polyamide 66 resin with a viscosity of 2.62 and terminal amine number of 41 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 80 kPa (gauge pressure). The temperature was then raised from 15°C to 255°C and maintained at 255°C for 6 hours, followed by cooling to 60°C for discharge. From the start of heating, the gas inside the reactor was vented every 10 minutes until the gauge pressure reached 10 kPa, and then nitrogen was immediately introduced to 80 kPa. This process was repeated until cooling was complete. Excess gas was then released from the reactor to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 5.32 and terminal amine number of 3 mmol / kg.

[0111] Example 4

[0112] Medium-viscosity polyamide 66 resin with a viscosity of 2.71 and a terminal amino group number of 43 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 20 kPa (gauge pressure). The temperature was then raised from 30°C to 220°C and maintained at 220°C for 5 hours, followed by cooling to 65°C for discharge. From the start of heating, nitrogen was continuously introduced to increase the pressure. When the pressure reached 20 kPa, the vent was opened, and when the pressure reached 5 kPa, the vent valve was closed. Venting was repeated once the pressure inside the reactor returned to 20 kPa, and this process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. Finally, high-viscosity polyamide 66 resin with a viscosity of 5.78 and a terminal amino group number of 5 mmol / kg was obtained.

[0113] Example 5

[0114] Medium-viscosity polyamide 66 resin with a viscosity of 2.89 and terminal amine number of 40 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 30 kPa (gauge pressure). The temperature was then raised from 20°C to 240°C and maintained at 240°C for 4 hours, followed by cooling to 60°C for discharge. From the start of heating, nitrogen was continuously introduced to increase the pressure. When the pressure reached 30 kPa, the vent was opened, and when the pressure reached 8 kPa, the vent valve was closed. Venting was repeated once the pressure inside the reactor returned to 30 kPa, and this process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. The final product was a high-viscosity polyamide 66 resin with a viscosity of 6.43 and terminal amine number of 2 mmol / kg. This high-viscosity polyamide 66 resin can be used for injection molding of railway track gauge baffle seats.

[0115] Example 6

[0116] Medium-viscosity polyamide 66 resin with a viscosity of 2.65 and a terminal amine number of 52 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 40 kPa (gauge pressure). The temperature was then raised from 25°C to 200°C and maintained at 200°C for 24 hours, before being cooled to 55°C and discharged. From the start of heating, nitrogen was continuously introduced to increase the pressure. When the pressure reached 40 kPa, the vent was opened, and when the pressure reached 10 kPa, the vent valve was closed. Venting was repeated once the pressure inside the reactor returned to 40 kPa, and this process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. Finally, high-viscosity polyamide 66 resin with a viscosity of 6.01 and a terminal amine number of 5 mmol / kg was obtained.

[0117] Example 7

[0118] Medium-viscosity polyamide 66 resin with a viscosity of 2.95 and a terminal amino group number of 29 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 25 kPa (gauge pressure). The temperature was then raised from 25°C to 160°C and maintained at 160°C for 30 hours, followed by cooling to 55°C for discharge. From the start of heating, nitrogen was continuously introduced to increase the pressure. When the pressure reached 25 kPa, the vent was opened. When the pressure reached 5 kPa, the vent valve was closed. Venting was repeated once the pressure inside the reactor returned to 25 kPa, and this process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. Finally, high-viscosity polyamide 66 resin with a viscosity of 3.89 and a terminal amino group number of 12 mmol / kg was obtained.

[0119] Example 8

[0120] Medium-viscosity polyamide 66 resin with a viscosity of 2.98 and terminal amino group number of 30 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 50 kPa (gauge pressure). The temperature was then raised from 20°C to 230°C and maintained at 230°C for 2 hours, followed by cooling to 60°C for discharge. From the start of heating, the exhaust valve was adjusted to an appropriate opening for slow venting. When the pressure inside the reactor dropped to 10 kPa, nitrogen was introduced to bring the pressure up to 50 kPa. This process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 4.83 and terminal amino group number of 8 mmol / kg.

[0121] Example 9

[0122] Medium-viscosity polyamide 66 resin with a viscosity of 2.67 and a terminal amine number of 50 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 60 kPa (gauge pressure). The temperature was then raised from 25°C to 210°C and maintained at 210°C for 0.5 hours, followed by cooling to 60°C before discharge. From the start of heating, the exhaust valve was adjusted to an appropriate opening for slow venting. When the pressure inside the reactor dropped to 15 kPa, nitrogen was introduced to raise the pressure to 60 kPa. This process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 3.29 and a terminal amine number of 26 mmol / kg. This polyamide 66 resin can be used in short-fiber products.

[0123] Example 10

[0124] Medium-viscosity polyamide 66 resin with a viscosity of 2.74 and a terminal amino group number of 50 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 40 kPa (gauge pressure). The temperature was then raised from 25°C to 190°C and maintained at 190°C for 16 hours, followed by cooling to 60°C before discharge. From the start of heating, the exhaust valve was adjusted to an appropriate opening for slow venting. When the pressure inside the reactor dropped to 6 kPa, nitrogen was introduced to bring the pressure up to 40 kPa. This process was repeated until cooling was complete. Excess gas was then discharged to atmospheric pressure, and the product was discharged. The final product was high-viscosity polyamide 66 resin with a viscosity of 4.18 and a terminal amino group number of 10 mmol / kg.

[0125] Comparative Example 1

[0126] Medium-viscosity polyamide 66 resin with a viscosity of 2.62 and terminal amine number of 41 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 80 kPa (gauge pressure). The temperature was then raised from 15°C to 255°C and maintained at 255°C for 6 hours, followed by cooling to 60°C for discharge. From the start of heating, the gas inside the reactor was vented every 60 minutes until the gauge pressure reached 10 kPa, and then nitrogen was immediately introduced until 80 kPa. This process was repeated until cooling was complete. Excess gas was then vented to atmospheric pressure, and the product was discharged. The final product was polyamide 66 resin with a viscosity of 2.93 and terminal amine number of 32 mmol / kg. Compared to Example 3, the viscosity increase of the polyamide 66 resin in this comparative example was smaller and did not reach the viscosity range of high-viscosity polyamide 66 resin defined in this invention.

[0127] Comparative Example 2

[0128] Medium-viscosity polyamide 66 resin with a viscosity of 2.71 and terminal amino group number of 43 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 20 kPa (gauge pressure). The temperature was then raised from 30°C to 220°C and maintained at 220°C for 5 hours. After cooling to 65°C, excess gas was discharged to atmospheric pressure, and the product was discharged. The reactor was kept sealed from the start of heating until the end of cooling. Finally, polyamide 66 resin with a viscosity of 2.83 and terminal amino group number of 41 mmol / kg was obtained. Compared to Example 4, the viscosity of the polyamide 66 resin in this comparative example did not increase significantly and did not reach the viscosity range of high-viscosity polyamide 66 resin defined in this invention.

[0129] Comparative Example 3

[0130] Low-viscosity polyamide 66 resin with a viscosity of 2.43 and a terminal amino group number of 30 mmol / kg was introduced into a solid-phase polycondensation reactor. The gas inside the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure inside the reactor reached 90 kPa (gauge pressure). The temperature was then raised from 25°C to 170°C and maintained at 170°C for 12 hours. After cooling to 50°C, excess gas was discharged to atmospheric pressure, and the product was discharged. From the start of heating until cooling and discharge, if the pressure inside the reactor increased, appropriate venting was performed to maintain the reactor pressure within the range of 90-100 kPa. Finally, polyamide 66 resin with a viscosity of 2.98 and a terminal amino group number of 2 mmol / kg was obtained. Compared to Example 2, the viscosity increase of the polyamide 66 resin in this comparative example was smaller and did not reach the viscosity range of high-viscosity polyamide 66 resin defined in this invention.

[0131] Application Example 1

[0132] A functional masterbatch, the preparation method of which includes the following steps:

[0133] 60 parts of aluminum stearate, 70 parts of calcium stearate, 100 parts of antioxidant (H3336), 10 parts of antioxidant (1098), and 10 parts of antioxidant (168) were mixed in proportion and then blended with 750 parts of polyamide 66 resin (viscosity 3.89) prepared in Example 7. The mixture was then extruded, cooled and granulated, dried, and sealed for later use.

[0134] Application Example 2

[0135] A functional masterbatch, the preparation method of which includes the following steps:

[0136] 50 parts of sodium stearate, 60 parts of magnesium stearate, 80 parts of antioxidant (H325), 10 parts of antioxidant (1098), 1 part of UV absorber (326), and 2 parts of nucleating agent (P22) were mixed in proportion and then co-extruded with 797 parts of polyamide 66 resin (viscosity 3.14) prepared in Example 2. The mixture was cooled, granulated, dried, and sealed for later use.

[0137] Application Example 3

[0138] A functional masterbatch, the preparation method of which includes the following steps:

[0139] 30 parts of magnesium stearate, 30 parts of calcium stearate, 62 parts of antioxidant (H321), 9 parts of antioxidant (SEED), 5 parts of UV absorber (234), and 20 parts of nucleating agent (CaV102) were mixed in proportion and then blended with 844 parts of polyamide 66 resin with a viscosity of 2.35 (the low-viscosity polyamide 66 resin used as raw material in Example 1 was purchased from Ningxia Ruitai Technology Co., Ltd.) and extruded. The mixture was then cooled, granulated, dried, and sealed for later use.

[0140] Application Example 4

[0141] A functional masterbatch, the preparation method of which includes the following steps:

[0142] 30 parts of sodium stearate, 14 parts of calcium stearate, 66 parts of antioxidant (H318), and 5 parts of antioxidant (1098) were mixed in proportion and then blended with 885 parts of polyamide 66 resin (viscosity 3.29) prepared in Example 9. The mixture was then extruded, cooled and granulated, dried, and sealed for later use.

[0143] Application Example 5

[0144] A functional masterbatch, the preparation method of which includes the following steps:

[0145] 10 parts of sodium lignite, 20 parts of antioxidant (TFB117), 10 parts of antioxidant (H10), and 10 parts of UV absorber (1164) were mixed in a certain proportion and then blended with 950 parts of polyamide 66 resin with a viscosity of 2.74 (the low-viscosity polyamide 66 resin used as raw material in Example 10 was purchased from Ningxia Ruitai Technology Co., Ltd.). The mixture was then extruded, cooled and granulated, dried, and sealed for later use.

[0146] Application Example 6

[0147] A polyamide 66 resin composition comprises 99.5 parts of the high-viscosity polyamide 66 resin prepared in Example 9 and 0.5 parts of the functional masterbatch prepared in Application Example 5. Before further processing into articles, the two are mixed in an environment below 100°C. When this composition is used in spun fibers, it improves processing stability (e.g., no degradation or discoloration occurs during the process), reduces filament breakage during spinning, improves the mechanical properties of nylon filaments, enhances colorability and dyeing depth, and extends service life at high temperatures. The polyamide 66 resin composition of this application example can also be mixed with color masterbatch and injection molded, offering advantages over virgin resin in maintaining product color, resisting UV aging, enabling rapid molding and demolding, and extending service life at high temperatures.

[0148] Application Example 7

[0149] A polyamide 66 resin composition comprises 98.8 parts of the high-viscosity polyamide 66 resin prepared in Example 1 and 1.2 parts of the functional masterbatch prepared in Application Example 1. Before further processing into an article, the two are mixed at an environment below 100°C. When the above composition is used for injection molding, the addition of the functional masterbatch improves the mechanical stability of the article at high temperatures without affecting its electrical properties. Simultaneously, it improves melt flowability and demolding efficiency during processing.

[0150] Application Example 8

[0151] A polyamide 66 resin composition comprises 97.1 parts of the high-viscosity polyamide 66 resin prepared in Example 3 and 2.9 parts of the functional masterbatch prepared in Application Example 4. The two components are mixed at an environment below 100°C before further processing into an article. When the above composition is used for injection molding, it improves melt flowability during processing. The addition of the functional masterbatch provides long-term protection for the stability of the article under harsh conditions (high temperature, chemicals, outdoor environments), prevents degradation of mechanical properties in the environment, and maintains the long-term surface gloss of the article.

[0152] Application Example 9

[0153] A polyamide 66 resin composition comprises 96.7 parts of the high-viscosity polyamide 66 resin prepared in Example 8 and 3.3 parts of the functional masterbatch prepared in Application Example 3. Before further processing into an article, the two are mixed in an environment below 100°C. When the above composition is used for injection molding, the addition of the functional masterbatch provides long-term protection for the stability of the article under harsh conditions (high temperature, chemicals, outdoor), prevents the degradation of mechanical properties in the environment, maintains the long-term surface gloss of the article, and improves the article's resistance to UV aging. During processing, it also improves melt flowability and facilitates rapid molding and demolding.

[0154] Application Example 10

[0155] A polyamide 66 resin composition comprises 95.2 parts of the high-viscosity polyamide 66 resin prepared in Example 4 and 4.8 parts of the functional masterbatch prepared in Application Example 2. Before further processing into articles, the two are mixed in an environment below 100°C. When used in industrial yarns, this composition helps reduce yarn breakage rate, improve dyeability, and enhance aging resistance. It can also be used in injection molding, where, compared to virgin resin, the composition exhibits improved melt stability, increased melt flowability, and faster molding and demolding effects. Furthermore, it improves the UV aging resistance of the finished product, enhances surface gloss, and increases color vibrancy.

[0156] Test case

[0157] I. Performance Testing of High-Viscosity Polyamide 66 Resin and its Compositions

[0158] The high-viscosity polyamide 66 resins prepared in Examples 4, 8 and 9, the medium-viscosity polyamide 66 resin used in Example 4, and the polyamide 66 resin compositions prepared in Application Examples 6, 9 and 10 were subjected to conventional mechanical property tests according to the following methods, and the results are shown in Table 1.

[0159] Test method for elongation at break: Refer to GB / T 1040 (ISO 527).

[0160] Test method for notched impact strength: Refer to GB / T 1043 (ISO 179).

[0161] As shown in Table 1, the high-viscosity polyamide 66 resin exhibits superior toughness compared to the medium-viscosity polyamide 66 resin (the raw material resin in Example 4). The properties of the high-viscosity polyamide 66 resin are consistent with the properties of the polyamide 66 resin composition in which it is the main component.

[0162] Table 1: Mechanical properties of some examples, applications, and raw material resins

[0163]

[0164] II. Performance Testing of Products Incorporating High-Viscosity Polyamide 66 Resin and its Compositions

[0165] The high-viscosity polyamide 66 resins prepared in Examples 4, 5, and 8, the medium-viscosity polyamide 66 resin used in Example 4, and the polyamide 66 resin compositions prepared in Application Examples 9 and 10 were injection molded into IV-8 railway gauge baffle seats and D1 pre-embedded sleeves according to the railway industry standard TB / T 1495-2020 of the People's Republic of China, and their performance was tested. The results are shown in Tables 2 and 3.

[0166] As can be seen from Tables 2 and 3, the IV-8 railway gauge baffle seat and D1 pre-embedded sleeve made from the raw material resin used in Example 4 failed the tests in flexural strength, shear strength, residual compression deformation, room temperature impact, low temperature impact, and fatigue test. However, the high viscosity polyamide 66 resin (Examples 4, 5, and 8) and polyamide 66 resin compositions (Application Example 9 and Application Example 10) prepared by the method of the present invention all passed the tests in the above-mentioned properties.

[0167] In addition, the IV-8 gauge baffle seat made of the polyamide 66 resin composition of Application Example 10 was used in a natural environment for one year, and then its performance was tested according to standard TB / T 1495-2020. The results showed that after one year of use, the baffle seat made of the polyamide 66 resin composition of Application Example 10 still met the performance requirements in Table 2 for drainage rate, flexural test, shear strength, residual compression deformation, room temperature impact, low temperature impact and fatigue test.

[0168] Table 2: Performance of IV-8 gauge baffle seats prepared from some examples, application examples and raw material resins

[0169]

[0170] Table 3: Performance of D1 Embedded Sleeves Prepared from Some Examples, Application Examples, and Raw Material Resin

[0171]

Claims

1. A polyamide 66 resin composition, characterized in that, The polyamide 66 resin composition comprises component I and component II, wherein component I is a high-viscosity polyamide 66 resin and component II is an additive; wherein the high-viscosity polyamide 66 resin has a relative viscosity of 3.0~6.5 and a terminal amino content ≤50mmol / kg.

2. A polyamide 66 resin composition, characterized in that, The polyamide 66 resin composition includes a main material and an additive masterbatch. The main material is a high-viscosity polyamide 66 resin, and the additive masterbatch includes a base material and additives. The base material is selected from one or more of polyamide 66, polyamide 6, and polyamide MXD6. The high-viscosity polyamide 66 resin has a relative viscosity of 3.0 to 6.5 and a terminal amino content of ≤50 mmol / kg.

3. The polyamide 66 resin composition according to claim 1 or 2, characterized in that, The high-viscosity polyamide 66 resin has a relative viscosity of 3.2~6.5 and a terminal amino content of ≤32mmol / kg; preferably, the high-viscosity polyamide 66 resin has a relative viscosity of 4.0~6.5 and a terminal amino content of ≤18mmol / kg; more preferably, the high-viscosity polyamide 66 resin has a terminal amino content of ≥1mmol / kg.

4. The polyamide 66 resin composition according to claim 1 or 2, characterized in that, The additive is one or more of the following: heat stabilizer, UV absorber, lubricant, nucleating agent, plasticizer, and colorant; Preferably, the heat stabilizer is an antioxidant; more preferably, the antioxidant is one or more selected from hindered phenolic heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, copper salt / cuprous salt heat stabilizers, phosphate / phosphite heat stabilizers, and aniline heat stabilizers; even more preferably, the antioxidant is one or more selected from the following additives: 1098, 1010, 1330, Nylostab seed, Addworks TFB117, TAD, 944, 106, 626, 627, 9228, H318, H320, H321, H325, H326, H3336, H3338, H10, H3311, FLEXAME, and OKAFLEX EM. Preferably, the UV absorber is one or more selected from UV absorbers with brand names 326, 234, 1164 and VSU; Preferably, the lubricant is a dispersant; more preferably, the dispersant is one or more selected from long-chain carboxylic acids and their salts or esters, organosilicon resins and ethylene bis-stearamide graft copolymers; even more preferably, the dispersant is one or more selected from palmitic acid, lignite acid, sodium stearate, calcium stearate, aluminum stearate, pentaerythritol stearate, polysiloxane powder, TAF, TAF-A and rice bran wax; Preferably, the nucleating agent is one or more selected from talc, silica, phthalate whiskers, magnesium oxide, aluminum oxide, zinc oxide, organophosphorus sodium, acetate, and products with the brand name P22 or CaV102. Preferably, the plasticizer is one or both selected from N-butyl-o-toluenesulfonamide and p-toluenesulfonamide; Preferably, the colorant is one or more selected from inorganic pigments, organic pigments and their masterbatches.

5. The polyamide 66 resin composition according to claim 1, characterized in that, In the polyamide 66 resin composition, component I accounts for 60% to 99.99% of the mass fraction of the polyamide 66 resin composition, preferably 90% to 99.99%; component II accounts for 0.01% to 40% of the mass fraction of the polyamide 66 resin composition, preferably 0.01% to 10%.

6. The polyamide 66 resin composition according to claim 2, characterized in that, The polyamide 66 resin composition has one or more of the following characteristics: In the polyamide 66 resin composition, the main ingredient accounts for 60% to 99.99% of the polyamide 66 resin composition by mass, preferably 90% to 99.99%; the additive masterbatch accounts for 0.01% to 40% of the polyamide 66 resin composition by mass, preferably 0.01% to 10%. The relative viscosity of the base material of the additive masterbatch is 2.0~4.0, preferably 2.3~3.9, and more preferably 2.7~3.9; The base material of the additive masterbatch is polyamide 66 resin, polyamide 6 resin or polyamide MXD6 resin, preferably polyamide 66 resin.

7. A method for preparing the polyamide 66 resin composition according to any one of claims 2-4 and 6, characterized in that, The method includes: preparing a functional masterbatch by combining additives and base materials, and then mixing it into a high-viscosity polyamide 66 resin, wherein the functional masterbatch is an additive masterbatch.

8. A pre-embedded sleeve, characterized in that, The pre-embedded sleeve contains the polyamide 66 resin composition according to any one of claims 1-6.

9. A railway gauge baffle seat, characterized in that, The railway gauge baffle seat contains the polyamide 66 resin composition according to any one of claims 1-6.

10. An injection molded part, film or filament prepared using the high viscosity polyamide 66 resin composition according to any one of claims 1-6; preferably, the injection molded part is a pre-embedded sleeve or a railway gauge baffle seat.

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