Polyamide 66 resin as well as preparation method and application thereof

Abstract

The invention belongs to the field of polyamide, and particularly relates to high-viscosity polyamide 66 resin as well as a preparation method and application thereof. The relative viscosity of the high-viscosity polyamide 66 resin is 3.0-6.5, and the amino-terminated group content is less than or equal to 50mmol / kg. The method for preparing the high-viscosity polyamide 66 resin is carried out under the positive pressure condition, the nitrogen atmosphere is adopted, and the temperature is always below the melting point of polyamide 66, so that materials are uniformly heated, and yellowing of the materials caused by air entering can be avoided. Downstream products prepared from the high-viscosity polyamide 66 resin have excellent properties such as high impact resistance, high shear resistance, high toughness and low-temperature toughness meeting use requirements.

Description

Technical Field

[0001] The invention belongs to the field of polyamide 66 resin, and specifically relates to a polyamide 66 resin and a preparation method and application thereof. Background Art

[0002] Nylon materials are widely used in aerospace, military, machinery, automobile and other industries due to their low density, wear resistance, fatigue resistance, good chemical stability, high temperature resistance, certain rigidity and toughness, etc. Polyamide 66 (PA66, polyhexamethylene adipamide) is one of the most widely used nylon materials. It is made by polycondensation of hexamethylenediamine and adipic acid. It has the advantages of high strength, corrosion resistance, fatigue resistance, impact resistance, friction resistance, softness and easy processing. Therefore, it is widely used in clothing, decoration, tire frame materials, conveyor belt canvas, cables, lifting belts and other fields.

[0003] The PA66 resin produced domestically is mainly low-viscosity and medium-viscosity products with low molecular weight. In some specific scenarios, such as long-term low-temperature environments, environments with frequent temperature changes, and long-term impact environments, the stability is poor, and brittle fractures and cracks are prone to occur, and the performance and service life cannot meet expectations. In terms of processing, the melt flow rate of low-viscosity and medium-viscosity products is relatively large. When used directly for extruded products (sheets, pipes), melt falling or casting will occur, making it difficult to form, and the scope of application is limited.

[0004] 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 superior to general PA66. It can be used to make injection molded parts, clothing yarns, airbag yarns, ultra-fine denier fibers, etc. that are subjected to long-term periodic stress, and has a broad market space and development prospects. In terms of processability, high-viscosity PA66 has high melt strength and low melt flow rate. When directly used for extrusion products, it is not easy to produce melt falling or casting phenomena, which makes up for and expands the application field of PA66 resin.

[0005] At the same time, the conventional production method of PA66, whether it is melt polymerization or salt polymerization, will eventually be transferred out of the kettle in the form of a melt. When the product viscosity is high, the melt viscosity is high and the outflow speed is slow, resulting in reduced production efficiency, and the melt stays for a long time under high temperature conditions in the kettle, which is prone to various side reactions and by-products, affecting product quality. If the melt outflow speed is increased by increasing the pressure in the kettle, a higher pressure than that used in conventional production is required, which poses certain safety risks. Summary of the invention

[0006] In view of the above-mentioned problems existing in the prior art, the present invention proposes a high-viscosity polyamide 66 resin with a relative viscosity value of 3.0 to 6.5 and a preparation method thereof, and forms a composition with different functional components according to the application scenario requirements for use in injection molding, film and fiber industries.

[0007] Specifically, one aspect of the present invention provides a high-viscosity polyamide 66 resin, wherein the relative viscosity of the high-viscosity polyamide 66 resin is 3.0 to 6.5, and the terminal amino group content is ≤50 mmol / kg.

[0008] In one or more embodiments, the high viscosity polyamide 66 resin has a relative viscosity of 3.2 to 6.5 and a terminal amino group content of ≤32 mmol / kg.

[0009] In one or more embodiments, the high viscosity polyamide 66 resin has a relative viscosity of 4.0 to 6.5 and a terminal amino group content of ≤18 mmol / kg.

[0010] In one or more embodiments, the terminal amino group content of the high viscosity polyamide 66 resin is ≥1 mmol / kg, such as ≥2 mmol / kg, ≥3 mmol / kg.

[0011] Another aspect of the present invention provides a method for preparing the high viscosity polyamide 66 resin described in any embodiment of the present invention, the method comprising: subjecting medium and low viscosity polyamide 66 resins to solid phase polycondensation reaction to obtain the high viscosity polyamide 66 resin.

[0012] In one or more embodiments, the relative viscosity of the medium-low viscosity polyamide 66 resin is ≥2.2 and <3.0, and the terminal amino group content is 20 to 80 mmol / kg.

[0013] In one or more embodiments, the method comprises the following steps:

[0014] Introduce low-medium viscosity polyamide 66 resin into a solid phase polycondensation reactor, replace the gas in the solid phase polycondensation reactor with nitrogen, raise the temperature of the solid phase polycondensation reactor to 150°C to 260°C, preferably 160°C to 240°C, maintain for 0.5 to 30 hours, preferably 2 to 24 hours, then cool to 20 to 70°C, preferably 30 to 60°C for discharge.

[0015] In one or more embodiments, during the entire process from heating to cooling, the method adopts the following method A, method B, method C or method D to make the pressure inside the reactor higher than the external atmospheric pressure, that is, the gauge pressure>0 kPa;

[0016] Method A: Continuously add nitrogen and continuously exhaust gas, preferably to a gauge pressure of 10 to 100 kPa;

[0017] Method B: Continuously introduce nitrogen and exhaust intermittently, for example, exhaust when the gauge pressure reaches 15-100 kPa, and then stop exhausting when the gauge pressure reaches 0-15 kPa (excluding 0 kPa), and exhaust again when the gauge pressure rises back to 15-100 kPa, and repeat this operation;

[0018] Method C: nitrogen is introduced intermittently and exhaust is continued. For example, when the gauge pressure is 0-15 kPa (excluding 0 kPa), nitrogen is introduced to 15-100 kPa. When the gauge pressure slowly drops to 0-15 kPa (excluding 0 kPa), the nitrogen introduction operation is repeated.

[0019] Mode D: nitrogen is introduced intermittently and exhausted intermittently, for example, nitrogen is introduced to a gauge pressure of 15 to 100 kPa, and after a period of time, the gas is exhausted to a gauge pressure of 0 to 15 kPa (excluding 0 kPa), and then nitrogen is immediately filled to a gauge pressure of 15 to 100 kPa, and the operation is repeated; the interval time is preferably 5 to 30 min.

[0020] Another aspect of the present invention provides a polyamide 66 resin composition, which comprises 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.

[0021] In one or more embodiments, the additive is selected from one or more of a thermal stabilizer, an anti-ultraviolet light absorber, a lubricant, a nucleating agent, a plasticizer, and a colorant.

[0022] In one or more embodiments, the mass fraction of component I in the polyamide 66 resin composition is 60% to 99.99%, for example, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0023] In one or more embodiments, the mass fraction of component I in the polyamide 66 resin composition is 90% to 99.99%.

[0024] In one or more embodiments, the mass fraction of component I in the polyamide 66 resin composition is 95% to 99.99%.

[0025] In one or more embodiments, the mass fraction of component II in the polyamide 66 resin composition is 0.01% to 40%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0026] In one or more embodiments, the mass fraction of component II in the polyamide 66 resin composition is 0.01% to 10%.

[0027] In one or more embodiments, the mass fraction of component II in the polyamide 66 resin composition is 0.01% to 5%.

[0028] In one or more embodiments, the heat stabilizer is an antioxidant, and the antioxidant is selected from one or more of hindered phenol heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, copper salt / cuprous salt heat stabilizers, phosphate / phosphite heat stabilizers and aniline heat stabilizers.

[0029] In one or more embodiments, the lubricant is a dispersant selected from one or more of long carbon chain carboxylic acids and salts or esters thereof, silicone resins, and ethylene bis stearamide graft copolymers.

[0030] Another aspect of the present invention provides a polyamide 66 resin composition, which includes 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 includes a base material and an additive, wherein the base material is selected from one or more of polyamide 6 (polycaprolactam), polyamide 66 and polyamide MXD6 (poly(meta-xylylene adipamide), and the additive is preferably selected from one or more of a thermal stabilizer, an anti-ultraviolet light absorber, a lubricant, a nucleating agent and a plasticizer.

[0031] In one or more embodiments, the mass fraction of the main ingredient in the polyamide 66 resin composition is 60% to 99.99%, for example, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0032] In one or more embodiments, the mass fraction of the main material in the polyamide 66 resin composition is 90% to 99.9%.

[0033] In one or more embodiments, the mass fraction of the main material in the polyamide 66 resin composition is 95% to 99.99%.

[0034] In one or more embodiments, the additive masterbatch accounts for 0.01% to 40% by mass of the polyamide 66 resin composition, for example, 5%, 10%, 15%, 20%, 25%, 30%, or 35%.

[0035] In one or more embodiments, the additive masterbatch accounts for 0.01% to 10% by mass of the polyamide 66 resin composition.

[0036] In one or more embodiments, the additive masterbatch accounts for 0.01% to 5% by mass of the polyamide 66 resin composition.

[0037] In one or more embodiments, the relative viscosity of the base material is 2.0 to 4.0.

[0038] In one or more embodiments, the relative viscosity of the base material is 2.3 to 3.9.

[0039] In one or more embodiments, the relative viscosity of the base material is 2.7 to 3.9.

[0040] In one or more embodiments, the total mass of the additive masterbatch is 1000 parts, in which the base material content is 700-999 parts, the heat stabilizer content is 1-150 parts, the anti-ultraviolet light absorber content is 0-10 parts, the lubricant content is 0-200 parts, the nucleating agent content is 0-100 parts, and the plasticizer content is 0-100 parts.

[0041] In one or more embodiments, the total mass of the additive masterbatch is 1000 parts, and the content of the base material in the additive masterbatch is 750-950 parts, the content of the heat stabilizer is 40-120 parts, the content of the anti-ultraviolet light absorber is 0-5 parts, the content of the lubricant is 10-100 parts, the content of the nucleating agent is 0-20 parts, and the content of the plasticizer is 0-30 parts.

[0042] Another aspect of the present invention provides use of the high viscosity polyamide 66 resin described in any embodiment of the present invention or the polyamide 66 resin composition described in any embodiment of the present invention in preparing injection molded parts, films or wires.

[0043] Another aspect of the present invention provides an injection molded part, a film or a wire prepared by using the high viscosity polyamide 66 resin described in any embodiment of the present invention or the polyamide 66 resin composition described in any embodiment of the present invention.

[0044] In one or more embodiments, the injection molded part is a railway gauge baffle seat or a railway embedded casing.

[0045] In one or more embodiments, the silk thread is brush silk or brown silk.

[0046] The present invention provides a high-viscosity polyamide 66 resin, whose relative viscosity can reach up to 6.5. Based on the high-viscosity polyamide 66 resin, the present invention provides a series of polyamide 66 resin compositions that can be flexibly formulated, which can respond to downstream application needs more quickly and more specifically. At the same time, the present invention provides a method for preparing polyamide 66 resin. The method is simple, effective, more targeted, and has low requirements for equipment, so that the chemical reaction occurs more evenly on the material. At the same time, it can reduce the thermal history and heating degree of the material reaction, thereby reducing side reactions, and reducing the possibility of yellowing of materials and products through positive pressure reactions. The downstream products prepared by the polyamide 66 resin of the present invention have excellent properties such as high impact resistance, high shear resistance, high toughness, and low-temperature toughness that meets the use requirements. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in this document. Unless otherwise specified, all technical and scientific terms used in this document have the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definitions in this specification shall prevail.

[0048] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0049] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0050] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0051] Herein, unless otherwise specified, percentage refers to mass percentage, ratio refers to mass ratio, and part refers to mass part.

[0052] Herein, the sum of the percentages of the various components of the composition is 100%.

[0053] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope defined by the present invention.

[0054] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0055] Herein, the "viscosity" refers to the relative viscosity value measured by the sulfuric acid method; the pressure values ​​mentioned are all "gauge pressure", that is, the pressure difference between the pressure and the atmospheric pressure outside the reactor.

[0056] The relative viscosity of the high viscosity polyamide 66 resin of the present invention is 3.0-6.5, 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 3.2-6.5, and more preferably 4.0-6.5.

[0057] The terminal amino group content of the high viscosity polyamide 66 resin of the present invention is ≤50mmol / kg, for example, 1mmol / kg, 2mmol / kg, 3mmol / kg, 5mmol / kg, 10mmol / kg, 15mmol / kg, 20mmol / kg, 25mmol / kg, 30mmol / kg, 35mmol / kg, 40mmol / kg, 41mmol / kg, 42mmol / kg, 43mmol / kg, 44mmol / kg, 45mmol / kg, 46mmol / kg, 47mmol / kg, 48mmol / kg, 49mmol / kg, preferably ≤32mmol / kg, more preferably ≤18mmol / kg.

[0058] The preparation methods of the high viscosity polyamide 66 resin of the present invention include but are not limited to: obtaining by direct melt polymerization of hexamethylenediamine and adipic acid; obtaining by polymerization of the intermediate product nylon salt after a salt-forming reaction and necessary post-treatment of hexamethylenediamine and adipic acid; obtaining by further condensation polymerization of medium-low viscosity polyamide 66 in a melt state through a screw extruder for continuous processing or secondary processing; obtaining by solid phase polycondensation of medium-low viscosity polyamide 66. Preferably, the high viscosity polyamide 66 resin of the present invention is obtained by solid phase polycondensation of medium-low viscosity polyamide 66.

[0059] In the present invention, the medium-low viscosity polyamide 66 resin refers to a polyamide 66 resin with a relative viscosity of 2.2 to 3.0 (excluding 3.0). The relative viscosity of the medium-low viscosity polyamide 66 resin can be 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9. The terminal amino content of the 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, 75 mmol / kg.

[0060] In the present invention, the selection of the raw material resin formula will affect the relative viscosity and the number of terminal amino groups of the prepared high-viscosity polyamide 66 resin. Therefore, the relative viscosity and the number of terminal amino groups of the high-viscosity polyamide 66 resin prepared by the present invention do not follow a single linear change.

[0061] The high viscosity polyamide 66 resin of the present invention can be prepared by the following solid phase polycondensation reaction:

[0062] Introduce a low- to medium-viscosity polyamide 66 resin into a solid phase polycondensation reactor, replace the gas in the solid phase polycondensation reactor with nitrogen, raise the temperature of the solid phase polycondensation reactor to 150°C to 260°C, for example, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, preferably 160°C to 240°C; maintain for 0.5 to 30 hours, for example, 0.6 hours , 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 cool to 20-70℃ for discharging, for example, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, preferably 30-60℃ for discharging.

[0063] In the present invention, the temperature of the solid phase polycondensation reaction is preferably 150°C to 260°C. If the temperature is too high, there is a risk of approaching the melting point. At the same time, the higher the temperature, the faster the reaction rate, which is not conducive to production stability and repeatability; if the temperature is too low, the reaction rate is too slow and the production efficiency is low. Therefore, controlling the equilibrium temperature of the reaction within the above range is conducive to obtaining the high viscosity polyamide 66 resin of the present invention.

[0064] In the present invention, the constant temperature maintenance time of the solid phase polycondensation reaction is preferably 0.5 to 30 hours. If the equilibrium time is too short, the operation 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 conducive to more efficiently obtaining the high-viscosity polyamide 66 resin of the present invention.

[0065] In the present 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; when the equilibrium temperature is constant, the longer the equilibrium time, the higher the viscosity of the polyamide 66 resin product obtained. Therefore, the matching equilibrium temperature and equilibrium time can be selected according to the relative viscosity of the target polyamide 66 resin and the ideal production time.

[0066] In the present invention, the discharge temperature is preferably 20 to 70° C. If the discharge temperature is set too high, the material is prone to yellowing when in contact with oxygen in the air during operation; if the discharge temperature is set too low, a longer cooling time is required, which increases energy consumption, labor and time costs accordingly.

[0067] In a preferred embodiment, in the solid phase polycondensation reaction of the present invention, the reaction is carried out under a nitrogen atmosphere, and during the entire process from heating to cooling, the following method A, method B, method C or method D is used to make the pressure in the reactor higher than the external atmospheric pressure, that is, the gauge pressure > 0 kPa.

[0068] Method A: nitrogen is added while excess gas is discharged. This method allows the nitrogen to carry away the by-product water produced by the reaction. At this time, the surface pressure of the reactor is preferably maintained at 10 to 100 kPa, for example 15 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, and 95 kPa.

[0069] Mode B: Continuously introduce nitrogen to increase the pressure and exhaust intermittently. Mode B can be to continuously introduce nitrogen, and when the pressure reaches 15-100kPa, such as 20kPa, 25kPa, 30kPa, 35kPa, 40kPa, 45kPa, 50kPa, 55kPa, 60kPa, 65kPa, 70kPa, 75kPa, 80kPa, 85kPa, 90kPa, 95kPa, exhaust the excess gas and close the exhaust valve, and when the pressure in the kettle rises back to 0-15kPa (excluding 0kPa), such as 1kPa, 2kPa, 3kPa, 4kPa, 5kPa, 6kPa, 7kPa, 8kPa, 9kPa, 10kPa, 11kPa, 12kPa, 13kPa, 14kPa, exhaust again, and repeat the operation.

[0070] Mode C: nitrogen is introduced intermittently and exhausted continuously. Mode C can be 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, nitrogen is introduced to 15 to 100 kPa, such as 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 5 The pressure is slowly reduced 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, 14 kPa, and the operation of introducing nitrogen is repeated.

[0071] Mode D: intermittent ventilation and exhaust. Mode D can be to introduce nitrogen to 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, 95 kPa, and maintain it for a period of time, then exhaust 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, 14 kPa, and immediately fill in new nitrogen to a gauge pressure of 15-100 kPa, and repeat the operation. The maintenance time after the nitrogen is introduced can be 5-30 min, for example, 5 min, 10 min, 20 min, 30 min.

[0072] When the polyamide 66 resin is prepared by the solid phase polycondensation method of the present invention, any of the above methods can be selected to maintain the gas pressure of the reaction system according to the conditions of the reactor.

[0073] The solid phase 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. The method herein can not only heat the material evenly, but also prevent the yellowing of the material caused by the entry of air.

[0074] In some embodiments, the polyamide 66 resin composition of the present invention contains component I and component II, component I is a 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: prepare the high viscosity polyamide 66 resin, and before discharging, use a melt pump to mix the additive with a small amount of polyamide 66 resin, mix it with the high viscosity polyamide 66 resin during the discharging process, and jointly mold, cool and granulate. This can also reduce modification and secondary processing. Although the high viscosity polyamide 66 resin melt has poor fluidity and difficult discharging, it can be improved by pressurization. There are equipment that meets the pressure requirements to meet the above process.

[0075] In some preferred embodiments, the additives included in the polyamide 66 resin composition of the present invention are one or more of a heat stabilizer, an anti-ultraviolet light absorber, a lubricant, a nucleating agent, a plasticizer and a colorant.

[0076] The heat stabilizer can be an antioxidant. The antioxidant that can be selected includes, but is not limited to, one or more of hindered phenol heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, cupric salt / cuprous salt heat stabilizers, phosphate / phosphite heat stabilizers, and aniline heat stabilizers, such as the auxiliary agents of the brands 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.

[0077] The ultraviolet light absorber includes, but is not limited to, ultraviolet light absorbers with brands such as 326, 234, 1164, and VSU.

[0078] The lubricant can be a dispersant. The dispersants that can be selected 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, montanic acid, sodium stearate, calcium stearate, aluminum stearate, pentaerythritol stearate, polysiloxane powder, TAF, TAF-A, and rice bran wax.

[0079] Nucleating agents include, but are not limited to, talc, silica, phthalate whiskers, magnesium oxide, aluminum oxide, zinc oxide, organic sodium hypophosphite, acetate, and commercial products with brand names P22 or CaV102.

[0080] Plasticizers include, but are not limited to, N-butyl o-toluenesulfonamide and p-toluenesulfonamide.

[0081] Colorants include but are not limited to inorganic pigments, organic pigments and masterbatches thereof.

[0082] In the present invention, the mass fraction of component I in the polyamide 66 resin composition can be 60% to 99.99%, for example, 65%, 70%, 75%, 80%, 85%, 90%, 95%; the mass fraction of component II in the polyamide 66 resin composition can be 0.01% to 40%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0083] In some preferred embodiments, the mass fraction of component I in the polyamide 66 resin composition is 90% to 99.99%, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.95%, preferably 95% to 99.99%; the mass fraction of component II in the polyamide 66 resin composition is 0.01% to 10%, for example, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, preferably 0.01% to 5%.

[0084] Herein, additives have multiple functions and are not limited to being used as a certain type of additive. For example, sodium stearate can also play the role of a nucleating agent, but it is not limited to being used only as a lubricant.

[0085] Herein, the base material of the additive masterbatch may be a polyamide 66 resin, a polyamide 6 resin or a polyamide MXD6 resin having a relative viscosity of 2.0 to 4.0, preferably a polyamide 66 resin. The relative viscosity of the base material may 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, 3.9, preferably 2.3 to 3.9, more preferably 2.7 to 3.9.

[0086] Herein, the main material refers to the high viscosity polyamide 66 resin in any embodiment of the present invention.

[0087] In this article, the additive can be added to the reactor during the solid phase polycondensation process and sintered on the surface of the polyamide 66 resin particles; or a certain proportion of the additive and the base material can be made into a functional masterbatch and then mixed into the high viscosity polyamide 66 resin particles. This method has higher flexibility in meeting downstream needs, and the functional masterbatch can be mixed into high viscosity polyamide 66 resin products of different viscosities according to needs. It is especially suitable for injection molded products because it can be mixed in the screw part of the injection molding machine during the injection molding melt process, avoiding secondary melting and granulation of the material due to additive modification, simplifying the process flow, and reducing the side reactions caused by secondary melting.

[0088] The additives herein are preferably prepared as additive masterbatches and then mixed into the resin composition.

[0089] In some embodiments, the polyamide 66 resin composition includes a base material and an additive masterbatch.

[0090] In the present invention, the mass fraction of the main material in the polyamide 66 resin composition can be 60% to 99.99%, for example, 65%, 70%, 75%, 80%, 85%, 90%, 95%; the mass fraction of the additive masterbatch in the polyamide 66 resin composition can be 0.01% to 40%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%.

[0091] In some preferred embodiments, the mass fraction of the main material in the polyamide 66 resin composition is 90% to 99.99%, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.95%, preferably 95% to 99.99%; the mass fraction of the additive masterbatch in the polyamide 66 resin composition is 0.01% to 10%, for example, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, preferably 0.01% to 5%.

[0092] Although high-viscosity polyamide 66 resin has better mechanical properties and performance, it usually has poor fluidity, which affects processing efficiency. After the functional masterbatch and high-viscosity polyamide 66 resin form a composite, the low-viscosity polyamide component used in the masterbatch base material can play a role in fluxing and flow, improving processing performance. Since the performance of the product is determined by the high-viscosity polyamide 66 resin, which accounts for the majority of its performance, the low-viscosity polyamide component of the masterbatch base material will not affect the product performance, but can improve the processing effect.

[0093] The injection molded parts prepared from the high viscosity polyamide 66 resin or the polyamide 66 resin composition in any embodiment of the present invention have been tested and can meet the application requirements in flexural tests, shear resistance, residual deformation, room temperature impact, low temperature impact, and fatigue tests, while similar products made from low viscosity polyamide 66 resin cannot meet the requirements.

[0094] The products provided herein include, but are not limited to, polyamide 66 resin compositions, functional masterbatches thereof, and downstream products thereof such as injection molded parts. These products preferably do not contain polymers other than polyamide, and the content of additives is preferably not higher than 10%, more preferably not higher than 5%. This can better preserve the performance characteristics of polyamide 66, and thus preserve the possibility of downstream applications in more fields. The high viscosity polyamide 66 resin and polyamide 66 resin composition of the present invention can be used not only for injection molded parts, but also for spinning processing and its related downstream applications, while controlling the cost of raw materials.

[0095] The present invention will be described below in the form of specific examples. It should be understood that these examples are illustrative only and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The compounds in the examples can all be purchased through commercial routes.

[0096] In the present invention, pressure refers to gauge pressure, that is, the difference between the pressure inside the reactor and the atmospheric pressure.

[0097] In the present invention, viscosity refers to the relative viscosity of the polymer solution measured by the sulfuric acid method. The viscosity is tested by using 96 wt % sulfuric acid as a solvent to dissolve the high viscosity polyamide 66 resin in the present invention, and preparing a sample solution with a polymer concentration of 0.01±0.00001 g / mL at 25° C. for testing. The specific operating details refer to the standard GB / T 12006.1-2009 (ISO 307:2007).

[0098] In the present invention, the test method for the number of terminal amino groups (i.e., the content of terminal amino groups) is:

[0099] (1) Preparation of standard solution: dilute 500 ml of 0.05 mol / L hydrochloric acid standard solution to 2500 ml of 0.01 mol / L hydrochloric acid solution;

[0100] (2) Calibration of standard solution: refer to GB / T 601-2016 standard method, weigh 0.2g of sodium carbonate calcined at 300°C, dissolve it in 50ml of pure water, use the hydrochloric acid solution prepared in step (1) to titrate the sodium carbonate solution, and use a potentiometric titrator to determine the titration end point; the concentration of the hydrochloric acid solution is calculated according to GB / T 601-2016 standard;

[0101] (3) Amino-terminal test

[0102] Refer to GB / T 38138-2019 method for measuring nylon terminal amino groups, weigh about 1.0g of the particles to be tested into a glass sample bottle, and record its exact mass (accurate to 0.001g); add 30mL of hexafluoroisopropanol solution, tighten the lid and seal it with a sealing film; let it stand for 1 day to dissolve, then shake it evenly with a vortex mixer, and then use the configured hydrochloric acid solution to test the terminal amino group value of the test solution by potentiometric titration. The calculation method of the terminal amino group value refers to GB / T 601-2016 standard.

[0103] In the examples and comparative examples of the present invention, low- and medium-viscosity polyamide 66 with different viscosities and terminal amino groups are purchased from Ningxia Ruitai Technology Co., Ltd. or its affiliated companies.

[0104] Example 1

[0105] A low-viscosity polyamide 66 resin with a viscosity of 2.35 and a terminal amino group number of 42 mmol / kg was introduced into a solid phase polycondensation reactor, and the gas in the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure in the reactor was 100 kPa (gauge pressure), and then the temperature was raised from 20°C to 180°C, and after maintaining at 180°C for 14 hours, the temperature was lowered to 50°C for discharge. Since the start of heating, the gas in the kettle was discharged to a gauge pressure of 10 kPa every 10 minutes, and then nitrogen was immediately introduced to 100 kPa. This was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 3.98 and a terminal amino group number of 1 mmol / kg was obtained.

[0106] Example 2

[0107] A 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, and the gas in the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure in the reactor was 90 kPa (gauge pressure), and then the temperature was raised from 25°C to 170°C, and after maintaining at 170°C for 12 hours, the temperature was lowered to 50°C for discharge. Since the start of heating, the gas in the kettle was discharged to a gauge pressure of 10 kPa every 10 minutes, and then nitrogen was immediately introduced to 90 kPa. This was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 3.14 and a terminal amino group number of 2 mmol / kg was obtained.

[0108] Example 3

[0109] A medium-viscosity polyamide 66 resin with a viscosity of 2.62 and a terminal amino group number of 41 mmol / kg was introduced into a solid phase polycondensation reactor, and the gas in the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure in the reactor was 80 kPa (gauge pressure), and then the temperature was raised from 15°C to 255°C, and after maintaining at 255°C for 6 hours, the temperature was lowered to 60°C for discharge. Since the start of heating, the gas in the kettle was discharged to a gauge pressure of 10 kPa every 10 minutes, and then nitrogen was immediately introduced to 80 kPa. This was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 5.32 and a terminal amino group number of 3 mmol / kg was obtained.

[0110] Example 4

[0111] A 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, and the gas in the reactor was replaced with nitrogen. Nitrogen was introduced until the pressure in the reactor was 20 kPa (gauge pressure), and then the temperature was raised from 30°C to 220°C. After maintaining at 220°C for 5 hours, the temperature was lowered to 65°C for discharge. Since the beginning of the temperature increase, nitrogen was continuously introduced to increase the pressure. When the pressure reached 20 kPa, the exhaust was exhausted. When the pressure reached 5 kPa, the exhaust valve was closed. When the pressure in the kettle returned to 20 kPa, the exhaust was exhausted again. This was repeated until the temperature reduction was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 5.78 and a terminal amino group number of 5 mmol / kg was obtained.

[0112] Example 5

[0113] A medium-viscosity polyamide 66 resin with a viscosity of 2.89 and a terminal amino group number of 40 mmol / kg is introduced into a solid phase polycondensation reactor, and the gas in the reactor is replaced by nitrogen, and nitrogen is introduced until the pressure in the reactor is 30 kPa (gauge pressure), and then the temperature is raised from 20°C to 240°C, maintained at 240°C for 4 hours, and then cooled to 60°C for discharge. Since the beginning of heating, nitrogen is continuously introduced to increase the pressure, and the exhaust is exhausted when the pressure reaches 30 kPa. When the pressure reaches 8 kPa, the exhaust valve is closed, and the pressure in the kettle is exhausted again when it rises back to 30 kPa. This is repeated until the cooling is completed, and the excess gas in the kettle is discharged to normal pressure and the material is discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 6.43 and a terminal amino group number of 2 mmol / kg is obtained. The high-viscosity polyamide 66 resin can be used for injection molding to produce railway gauge baffle seats.

[0114] Example 6

[0115] A medium viscosity polyamide 66 resin with a viscosity of 2.65 and a terminal amino group number of 52 mmol / kg is introduced into a solid phase polycondensation reactor, and the gas in the reactor is replaced by nitrogen. Nitrogen is introduced until the pressure in the reactor is 40 kPa (gauge pressure), and then the temperature is raised from 25°C to 200°C. After maintaining at 200°C for 24 hours, the temperature is lowered to 55°C for discharge. Since the beginning of the temperature increase, nitrogen is continuously introduced to increase the pressure. When the pressure reaches 40 kPa, the exhaust is exhausted. When the pressure reaches 10 kPa, the exhaust valve is closed. When the pressure in the kettle rises back to 40 kPa, the exhaust is exhausted again. This is repeated until the temperature reduction is completed, and the excess gas in the kettle is discharged to normal pressure and the material is discharged. Finally, a high viscosity polyamide 66 resin with a viscosity of 6.01 and a terminal amino group number of 5 mmol / kg is obtained.

[0116] Example 7

[0117] A 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, and the gas in the reactor was replaced with nitrogen. Nitrogen was introduced until the pressure in the reactor was 25 kPa (gauge pressure), and then the temperature was raised from 25°C to 160°C. After maintaining at 160°C for 30 hours, the temperature was lowered to 55°C for discharge. Since the beginning of the temperature increase, nitrogen was continuously introduced to increase the pressure. When the pressure reached 25 kPa, the exhaust was exhausted. When the pressure reached 5 kPa, the exhaust valve was closed. When the pressure in the kettle returned to 25 kPa, the exhaust was exhausted again. This was repeated until the temperature reduction was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 3.89 and a terminal amino group number of 12 mmol / kg was obtained.

[0118] Example 8

[0119] A medium viscosity polyamide 66 resin with a viscosity of 2.98 and a terminal amino group number of 30 mmol / kg was introduced into a solid phase polycondensation reactor, and the gas in the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure in the reactor was 50 kPa (gauge pressure), and then the temperature was raised from 20°C to 230°C, maintained at 230°C for 2 hours, and then cooled to 60°C for discharge. From the beginning of heating, the exhaust valve was adjusted to an appropriate opening to slowly exhaust. When the pressure in the kettle dropped to 10 kPa, nitrogen was introduced to 50 kPa, and this was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high viscosity polyamide 66 resin with a viscosity of 4.83 and a terminal amino group number of 8 mmol / kg was obtained.

[0120] Example 9

[0121] A medium-viscosity polyamide 66 resin with a viscosity of 2.67 and a terminal amino group number of 50 mmol / kg was introduced into a solid phase polycondensation reactor, and the gas in the reactor was replaced with nitrogen, and nitrogen was introduced until the pressure in the reactor was 60 kPa (gauge pressure), and then the temperature was raised from 25°C to 210°C, and after maintaining at 210°C for 0.5h, the temperature was lowered to 60°C for discharge. Since the beginning of the temperature rise, the exhaust valve was adjusted to an appropriate opening to slowly exhaust. When the pressure in the kettle dropped to 15 kPa, nitrogen was introduced to 60 kPa. This was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 3.29 and a terminal amino group number of 26 mmol / kg was obtained. The polyamide 66 resin can be used for staple fiber products.

[0122] Example 10

[0123] A 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, and the gas in the reactor was replaced with nitrogen. Nitrogen was introduced until the pressure in the reactor was 40 kPa (gauge pressure), and then the temperature was raised from 25°C to 190°C. After maintaining at 190°C for 16 hours, the temperature was lowered to 60°C for discharge. From the beginning of heating, the exhaust valve was adjusted to an appropriate opening to slowly exhaust. When the pressure in the kettle dropped to 6 kPa, nitrogen was introduced to 40 kPa. This was repeated until the cooling was completed, and the excess gas in the kettle was discharged to normal pressure and the material was discharged. Finally, a high-viscosity polyamide 66 resin with a viscosity of 4.18 and a terminal amino group number of 10 mmol / kg was obtained.

[0124] Comparative Example 1

[0125] A medium viscosity polyamide 66 resin with a viscosity of 2.62 and a terminal amino group number of 41mmol / kg is introduced into a solid phase polycondensation reactor, and the gas in the reactor is replaced by nitrogen, and nitrogen is introduced until the pressure in the reactor is 80kPa (gauge pressure), then the temperature is raised from 15°C to 255°C, and after maintaining at 255°C for 6h, the temperature is lowered to 60°C for discharging. Since the beginning of heating, the gas in the kettle is discharged to a gauge pressure of 10kPa every 60min, and then nitrogen is immediately introduced to 80kPa. After repeating this until the cooling is completed, the excess gas in the kettle is discharged to normal pressure and the material is discharged. Finally, a polyamide 66 resin with a viscosity of 2.93 and a terminal amino group number of 32mmol / kg is obtained. Compared with Example 3, the viscosity of the polyamide 66 resin in this comparative example increases less, and does not reach the viscosity range of the high viscosity polyamide 66 resin defined in the present invention.

[0126] Comparative Example 2

[0127] A medium viscosity polyamide 66 resin with a viscosity of 2.71 and a terminal amino group number of 43 mmol / kg is introduced into a solid phase polycondensation reactor, the gas in the reactor is replaced by nitrogen, and nitrogen is introduced until the pressure in the reactor is 20 kPa (gauge pressure), then the temperature is raised from 30°C to 220°C, maintained at 220°C for 5 hours, and after cooling to 65°C, the excess gas in the kettle is discharged to normal pressure and the material is discharged. From the beginning of heating to the end of cooling, the reactor is kept closed. Finally, a polyamide 66 resin with a viscosity of 2.83 and a terminal amino group number of 41 mmol / kg is obtained. Compared with Example 4, the viscosity of the polyamide 66 resin in this comparative example does not increase significantly, and does not reach the viscosity range of the high viscosity polyamide 66 resin defined in the present invention.

[0128] Comparative Example 3

[0129] A low-viscosity polyamide 66 resin with a viscosity of 2.43 and a terminal amino group number of 30 mmol / kg is introduced into a solid phase polycondensation reactor, and the gas in the reactor is replaced by nitrogen, and nitrogen is introduced until the pressure in the reactor is 90 kPa (gauge pressure), then the temperature is raised from 25°C to 170°C, and after maintaining at 170°C for 12 hours, the temperature is lowered to 50°C, and the excess gas in the kettle is discharged to normal pressure, and the material is discharged. From the beginning of heating to before cooling and discharging, if the pressure in the kettle increases, the exhaust is appropriate to keep the pressure of the reactor in the range of 90 to 100 kPa. Finally, a polyamide 66 resin with a viscosity of 2.98 and a terminal amino group number of 2 mmol / kg is obtained. Compared with Example 2, the viscosity of the polyamide 66 resin in this comparative example increases less, and does not reach the viscosity range of the high-viscosity polyamide 66 resin defined in the present invention.

[0130] Application Example 1

[0131] A functional masterbatch, the preparation method of which comprises the following steps:

[0132] The additives of aluminum stearate 60 parts, calcium stearate 70 parts, antioxidant (H3336) 100 parts, antioxidant (1098) 10 parts, and antioxidant (168) 10 parts were mixed in proportion, and blended and extruded with 750 parts of the polyamide 66 resin (viscosity 3.89) prepared in Example 7, cooled and granulated, dried to moisture, and sealed for storage.

[0133] Application Example 2

[0134] A functional masterbatch, the preparation method of which comprises the following steps:

[0135] The additives sodium stearate 50 parts, magnesium stearate 60 parts, antioxidant (H325) 80 parts, antioxidant (1098) 10 parts, anti-ultraviolet light absorber (326) 1 part, nucleating agent (P22) 2 parts are mixed in proportion, and blended and extruded with 797 parts of polyamide 66 resin (viscosity 3.14) prepared in Example 2, cooled and granulated, dried to moisture, and sealed for storage.

[0136] Application Example 3

[0137] A functional masterbatch, the preparation method of which comprises the following steps:

[0138] The additives of magnesium stearate 30 parts, calcium stearate 30 parts, antioxidant (H321) 62 parts, antioxidant (SEED) 9 parts, anti-ultraviolet light absorber (234) 5 parts, nucleating agent (CaV102) 20 parts are mixed in proportion, and blended and extruded with 844 parts of polyamide 66 resin with a viscosity of 2.35 (the low-viscosity polyamide 66 resin used as the raw material in Example 1 is purchased from Ningxia Ruitai Technology Co., Ltd.), cooled and granulated, dried to moisture, and sealed for storage.

[0139] Application Example 4

[0140] A functional masterbatch, the preparation method of which comprises the following steps:

[0141] The additives sodium stearate 30 parts, calcium stearate 14 parts, antioxidant (H318) 66 parts, antioxidant (1098) 5 parts were mixed in proportion, and blended and extruded with 885 parts of polyamide 66 resin (viscosity 3.29) prepared in Example 9, cooled and granulated, dried to moisture, and sealed for storage.

[0142] Application Example 5

[0143] A functional masterbatch, the preparation method of which comprises the following steps:

[0144] 10 parts of additive sodium montanate, 20 parts of antioxidant (TFB117), 10 parts of antioxidant (H10), and 10 parts of anti-ultraviolet absorber (1164) are mixed in proportion, and blended and extruded with 950 parts of polyamide 66 resin with a viscosity of 2.74 (the low-viscosity polyamide 66 resin used as the raw material in Example 10 is purchased from Ningxia Ruitai Technology Co., Ltd.), cooled and granulated, dried to moisture, and sealed for storage.

[0145] Application Example 6

[0146] A polyamide 66 resin composition is composed of 99.5 parts of high-viscosity polyamide 66 resin prepared in Example 9 and 0.5 parts of functional masterbatch prepared in Application Example 5. Before further processing into products, the two are mixed in an environment of less than 100°C. The above composition is used for spinning fibers, which has the effects of improving processing stability (for example, no degradation and discoloration during the process), reducing the broken yarn rate during spinning, improving the mechanical properties of nylon yarn, improving colorability and dyeing depth, and extending the service life at high temperatures; the polyamide 66 resin composition of this application example can also be mixed with masterbatch and added to an injection molding machine for injection molding. Compared with the original resin, it has the effects of maintaining the color of the product, resisting UV aging, rapid molding and demoulding, and extending the service life at high temperatures.

[0147] Application Example 7

[0148] A polyamide 66 resin composition is composed of 98.8 parts of high-viscosity polyamide 66 resin prepared in Example 1 and 1.2 parts of functional masterbatch prepared in Application Example 1. Before further processing into products, the two are mixed in an environment of less than 100° C. The composition is used for injection molding. The addition of the functional masterbatch has the effect of improving the mechanical stability of the product at high temperature without affecting the electrical properties of the product, and at the same time has the effect of improving melt fluidity and demolding efficiency during processing.

[0149] Application Example 8

[0150] A polyamide 66 resin composition is composed of 97.1 parts of high-viscosity polyamide 66 resin prepared in Example 3 and 2.9 parts of functional masterbatch prepared in Application Example 4. Before further processing into products, the two are mixed in an environment of less than 100°C. The composition is used for injection molding, which has the effect of improving melt fluidity during the processing; the addition of the functional masterbatch has the effect of long-term protection of the stability of the product under harsh conditions (high temperature, chemicals, outdoor), preventing the attenuation of mechanical properties in the environment, and maintaining the long-term surface gloss of the product unchanged.

[0151] Application Example 9

[0152] A polyamide 66 resin composition is composed of 96.7 parts of high-viscosity polyamide 66 resin prepared in Example 8 and 3.3 parts of functional masterbatch prepared in Application Example 3. Before further processing into products, the two are mixed in an environment of less than 100°C. The composition is used for injection molding. The addition of the functional masterbatch has the effect of long-term protection of the stability of the product under harsh conditions (high temperature, chemicals, outdoor), preventing the attenuation of mechanical properties in the environment, maintaining the long-term surface gloss of the product unchanged, and improving the UV aging resistance of the product; in the processing process, it has the effect of improving melt fluidity and rapid molding and demolding.

[0153] Application Example 10

[0154] A polyamide 66 resin composition is composed of 95.2 parts of high-viscosity polyamide 66 resin prepared in Example 4 and 4.8 parts of functional masterbatch prepared in Application Example 2. Before further processing into products, the two are mixed in an environment of less than 100°C. The above composition is used for industrial yarns, which helps to reduce the yarn breakage rate, improve dyeability and aging resistance; it can also be used for injection molding. Compared with the original resin, the composition has the effects of improved melt stability, improved melt fluidity, rapid molding and demolding, and improved UV aging resistance, surface gloss and dyeing brightness of the products.

[0155] Test Case

[0156] 1. Performance test of high viscosity polyamide 66 resin and its composition

[0157] The high viscosity polyamide 66 resin prepared in Examples 4, 8 and 9, the raw material resin used in Example 4, i.e., the medium viscosity polyamide 66 resin, 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. The results are listed in Table 1.

[0158] Test method for elongation at break: refer to GB / T 1040 (ISO 527).

[0159] Notched impact strength test method: refer to GB / T 1043 (ISO 179).

[0160] As can be seen from Table 1, the high viscosity polyamide 66 resin has better toughness than the medium viscosity polyamide 66 resin (raw material resin of Example 4). The performance of the high viscosity polyamide 66 resin is consistent with the performance of the polyamide 66 resin composition of which it is the main component.

[0161] Table 1: Mechanical properties of some embodiments, application examples and raw material resins

[0162]

[0163] 2. Product performance test of high viscosity polyamide 66 resin and its composition

[0164] The high viscosity polyamide 66 resin prepared in Examples 4, 5 and 8, the raw material resin used in Example 4, i.e., the medium viscosity polyamide 66 resin, and the polyamide 66 resin composition prepared in Application Examples 9 and 10 were respectively made into IV-8 railway gauge baffle seats and D1 embedded casings by injection molding in accordance with the railway industry standard TB / T 1495-2020 of the People's Republic of China, and performance tests were carried out. The results are shown in Tables 2 and 3.

[0165] It can be seen from Tables 2 and 3 that the IV-8 railway gauge baffle seat and D1 embedded sleeve made from the raw resin used in Example 4 all failed to meet the standards in flexural test, shear resistance, compression residual deformation, normal temperature impact, low temperature impact and fatigue test, while the high viscosity polyamide 66 resin (Example 4, Example 5 and Example 8) and the polyamide 66 resin composition (Application Example 9 and Application Example 10) obtained by the preparation method of the present invention all met the standards in the above performances.

[0166] 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 the performance test was performed according to the standard TB / T 1495-2020. The results show that after one year of use, the baffle seat made of the polyamide 66 resin composition of Application Example 10 still meets the performance requirements in Table 2 in terms of drainage rate, flexure test, shear resistance, compression residual deformation, normal temperature impact, low temperature impact and fatigue test.

[0167] Table 2: Performance of IV-8 gauge baffle seat prepared from some embodiments, application examples and raw material resins

[0168]

[0169] Table 3: Performance of D1 pre-buried casing prepared from some embodiments, application examples and raw material resins

[0170]

Claims

1. A high viscosity polyamide 66 resin, characterized in that: The high-viscosity polyamide 66 resin has a relative viscosity of 3.0 to 6.5 and a terminal amino group content of ≤50 mmol / kg.

2. The high viscosity polyamide 66 resin according to claim 1, characterized in that: The high-viscosity polyamide 66 resin has a relative viscosity of 3.2 to 6.5 and a terminal amino group content of ≤32 mmol / kg.

3. The high viscosity polyamide 66 resin according to claim 1, characterized in that: The high-viscosity polyamide 66 resin has a relative viscosity of 4.0 to 6.5 and a terminal amino group content of ≤18 mmol / kg.

4. The high viscosity polyamide 66 resin according to claim 1, characterized in that: The terminal amino group content of the high-viscosity polyamide 66 resin is ≥1 mmol / kg.

5. A method for preparing the high viscosity polyamide 66 resin according to any one of claims 1 to 4, characterized in that: The method comprises: subjecting a medium-low viscosity polyamide 66 resin to a solid phase polycondensation reaction to obtain the high-viscosity polyamide 66 resin; the medium-low viscosity polyamide 66 resin has a relative viscosity of ≥2.2 and <3.0, and a terminal amino group content of 20 to 80 mmol / kg.

6. The method according to claim 5, characterized in that The method comprises the following steps: Introduce low-medium viscosity polyamide 66 resin into a solid phase polycondensation reactor, replace the gas in the solid phase polycondensation reactor with nitrogen, raise the temperature of the solid phase polycondensation reactor to 150°C to 260°C, maintain for 0.5 to 30 hours, and then cool down to 20 to 70°C for discharge.

7. The method according to claim 5, characterized in that In the method, during the whole process from heating to cooling, the pressure in the reactor is made higher than the external atmospheric pressure by adopting the following method A, method B, method C or method D, that is, the gauge pressure is greater than 0 kPa; Method A: Continuously introduce nitrogen and continuously exhaust gas; Method B: Continuously introduce nitrogen and exhaust intermittently; Method C: intermittent nitrogen introduction and continuous exhaust; Method D: intermittent ventilation with nitrogen and intermittent exhaust.

8. A polyamide 66 resin composition, characterized in that: The polyamide 66 resin composition comprises component I and component II, wherein component I is the high-viscosity polyamide 66 resin according to any one of claims 1 to 4, and component II is an additive.

9. A polyamide 66 resin composition, characterized in that: The polyamide 66 resin composition comprises a main material and an additive masterbatch, wherein the main material is the high-viscosity polyamide 66 resin described in any one of claims 1 to 4, and the additive masterbatch comprises a base material and an additive, wherein the base material is selected from one or more of polyamide 66, polyamide 6 and polyamide MXD6.

10. An injection molded part, a film or a silk thread prepared by using the high viscosity polyamide 66 resin according to any one of claims 1 to 4, or the polyamide 66 resin composition according to claim 8 or 9.

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