Uvioresistant high-transparency polyamide material and preparation method thereof

Abstract

The application provides a kind of UV-resistant transparent polyamide material and its preparation method, the raw material of the UV-resistant transparent polyamide material includes binary acid, binary amine, catalyst and deionized water;The binary amine includes double alicyclic binary amine and single alicyclic binary amine;The binary acid includes aliphatic binary acid and alicyclic binary acid;With the total mole number of binary amine as 100%, the mole content of double alicyclic binary amine in the alicyclic binary diamine is 85%-98%, the mole content of single alicyclic binary amine is 2%-15%, the mole content of alicyclic binary acid in the binary acid is 1-10%, and the content of aliphatic binary acid is 90-99%.The polyamide material provided by the application has UV resistance, higher light transmittance, does not contain additional light stabilizer, and has good mechanical properties, and maintains good light transmittance after UV irradiation.

Description

Technical Field

[0001] This invention belongs to the field of polyamide material technology, specifically relating to a UV-resistant transparent polyamide material and its preparation method. Background Technology

[0002] Transparent polymer materials, due to their high transparency and ease of molding and processing, are widely used in architectural lighting components, transportation facilities, medical devices, optical products, and aerospace. Currently, the main transparent polymer materials used in high-end applications with high performance requirements are polymethyl methacrylate (PMMA) and polycarbonate (PC), both with light transmittance exceeding 90%. PMMA has advantages such as high surface hardness, excellent UV aging resistance, and high cost-effectiveness, but it also has disadvantages such as low impact strength, poor friction and wear resistance, low operating temperature, and poor resistance to organic solvents. While PC possesses excellent mechanical properties and resistance to high and low temperatures, it suffers from poor UV aging and solvent resistance, making it prone to stress cracking and insufficient friction and wear resistance. These problems severely affect the application and service life of transparent components in scenarios with large temperature and light intensity variations, or high-speed movement in dusty environments. In contrast, transparent polyamides, besides possessing high light transmittance and excellent mechanical properties similar to PC and PMMA, also exhibit outstanding toughness, abrasion resistance, solvent resistance, dimensional stability, and resistance to high and low temperatures, thus compensating for the significant defects of PMMA and PC materials. However, polyamide materials have a fatal flaw: under the influence of ultraviolet light and oxygen, they are prone to photoaging, leading to yellowing and decreased light transmittance. Currently, the main approach is to add UV-resistant additives to improve their UV aging resistance. However, these additives tend to migrate or precipitate onto the surface of the product during use, resulting in decreased light transmittance or UV aging resistance, affecting the product's service performance and lifespan. Therefore, preparing transparent polyamide resins with intrinsic UV resistance and excellent performance is a prerequisite for developing UV-resistant, high and low temperature resistant, scratch-resistant, and solvent-resistant transparent materials with no or low additive content, and has extremely important industrial application value.

[0003] Currently, the preparation of transparent polyamides mainly involves copolymerizing multiple monomers to disrupt their crystallinity and achieve transparency. Research has found two main reasons why ultraviolet light causes polyamide materials to yellow. First, ultraviolet light induces the oxidation of methylene groups linked to the nitrogen atom of the amide bond on the macromolecular backbone, forming carbonyl groups and an imide structure, which appears yellow. Second, the amine groups (-NH2) at the ends of the macromolecular chains easily generate imines and conjugated structures under photo-oxidation conditions, leading to yellowing and performance degradation. Furthermore, the chemical structure of the macromolecular structural units significantly affects the photostability of polyamides. To increase the service temperature of transparent polyamides, their macromolecular structures typically contain a certain proportion of aromatic ring structural units. The presence of aromatic rings intensifies the material's absorption of ultraviolet light and exacerbates color changes. In contrast, alicyclic monomers have saturated cyclic structures, do not contain conjugated systems, and exhibit weaker ultraviolet absorption, making them more conducive to improving the material's UV resistance. Therefore, from a molecular design perspective, constructing a structure without aromatic rings and effectively controlling the content of terminal amine groups to overcome the bottleneck of insufficient UV resistance of the macromolecular backbone is a key foundational work for the preparation of highly UV-resistant transparent polyamide resins and the development of high-performance UV-resistant and highly transparent polyamide products.

[0004] CN103483581A discloses a transparent polyamide containing side groups and cyclic structural units, and its synthesis method. This method improves the transparency and wear resistance of the polyamide by disrupting the regularity of the macromolecular chain. However, the transparent polyamide raw material in this patent uses a large number of benzene-ring-containing monomers, and the material itself does not possess UV resistance. Furthermore, the preparation process involves salt formation followed by polymerization, making the process relatively complex. In addition, the salt formation process requires a large amount of organic solvents, posing safety hazards and difficulties in waste treatment. CN103910877B discloses a transparent polyamide obtained by copolymerizing aliphatic diacids, alicyclic diamines, and amide salts. It mainly uses a quenching method to form microcrystals, making the grain size smaller than the visible light wavelength to balance transparency and certain mechanical properties. From this composition, it can be seen that the macromolecular backbone contains a large number of methylene groups linked to the N-terminal amide bond, which are sensitive to ultraviolet light and prone to yellowing outdoors, affecting color, transparency, and service life.

[0005] CN103435796B discloses a semi-aromatic transparent polyamide material and its preparation method. The transparent polyamide material is obtained by random copolymerization of a semi-aromatic amide salt and an aliphatic amide salt, combined with nucleating agents, antioxidants, whitening agents, and other additives. From a molecular structural perspective, the introduction of aromatic ring structures increases the material's sensitivity to ultraviolet light absorption and exacerbates yellowing, thus lacking intrinsic UV resistance.

[0006] CN106916296A discloses a method for preparing aliphatic transparent polyamide and the aliphatic transparent polyamide itself. CN106916297A discloses a method for preparing transparent polyamide and the transparent polyamide itself. Both patent applications produce polyamide materials with high transparency. Both of these patent applications require the prior preparation of a polyamide salt, followed by melt polymerization to obtain the product, making the process relatively complex. Furthermore, the salt formation process requires the use of large amounts of organic solvents, posing safety hazards and difficulties in waste treatment.

[0007] CN107513163B discloses a method for preparing a highly transparent and tough nylon 66 resin, which aims to balance transparency and toughness by blending the matrix resin with glass fiber. CN109265677B discloses a method for preparing a high-temperature resistant transparent polyamide, focusing on improving heat resistance and processing stability by introducing a novel diamine with large-volume side groups and improving the gas-liquid separation device. CN110746596B discloses a copolymer transparent polyamide and its preparation method, which balances glass transition temperature, transparency, and thermal properties through melt copolymerization of three diamines and three diacids. CN112480395A discloses a transparent nylon HTD10 material and its preparation method. These patent applications all introduce a large number of benzene ring structures and aliphatic diamines into the structure, significantly increasing the material's absorption of ultraviolet light, making the material itself sensitive to ultraviolet light and affecting its performance. None of the above solutions consider the problem of the macromolecular chain's ability to resist ultraviolet light.

[0008] CN115894902B discloses a transparent nylon resin, its preparation method, and its application. High transparency is achieved by introducing a diamine containing cyclic side groups to disrupt the molecular chain regularity. This method involves a large number of methylene groups linked to the N-terminal amide bond in the macromolecular backbone, which are easily oxidized by ultraviolet light to produce chromophores and cause yellowing. CN111269413B discloses a yellowing-resistant polyamide resin and its preparation method, using a combination of polyamide 5X, an anti-yellowing agent, and an antioxidant to improve yellowing resistance under high temperature and ultraviolet conditions. CN118834525A discloses an ultraviolet-resistant PA for automotive parts and its preparation method, obtaining an ultraviolet-resistant polyamide material by blending a nylon matrix resin with various additives. The matrix resins used in both methods do not inherently possess ultraviolet resistance.

[0009] CN113583235B discloses a transparent polyamide resin, its preparation method, and its applications. The raw materials simultaneously contain specific structure-disrupting monomers and ultraviolet absorbers to achieve transparency and a certain degree of ultraviolet resistance, making it suitable for lens materials. According to the disclosure, the macromolecular backbone contains a large number of methylene groups linked to the N-terminal amide bond, which are easily excited and oxidized by ultraviolet light to produce chromophores, resulting in yellowing. It lacks intrinsic ultraviolet resistance, and its ultraviolet resistance is mainly achieved through the addition of external additives, which presents problems such as additive migration and exudation.

[0010] In summary, there is currently no technology for preparing transparent polyamides with high transparency, low haze, and low yellowing that possess inherent UV aging resistance in the polyamide macromolecule chain. Therefore, it is necessary to develop a UV-resistant, high-transparency polyamide material and its preparation method. This method should achieve a balance between material transparency and UV resistance by synergistically regulating molecular chain structure, crystallization behavior, and photo-oxidation sensitive sites, thereby reducing dependence on external additives. Summary of the Invention

[0011] To address the problems of photo-oxidative degradation, yellowing, and performance decline in existing nylon materials under ultraviolet light irradiation, this invention provides a UV-resistant transparent polyamide material without added light stabilizers and its preparation method. This invention modulates the polyamide molecular structure by reacting an ester-cyclic monomer with an amino group linked to an aliphatic diacid to construct a transparent polyamide structure whose main chain does not contain methylene groups linked to the N-terminal amide bond or benzene rings, thus achieving a higher glass transition temperature and lower UV absorption. Furthermore, HTDA diamine is introduced as a capping agent to cyclize and cap the molecular chain ends, thereby reducing photo-oxidative active sites, inhibiting the formation of chromophores, and improving the material's UV aging resistance. Through this structural design, the prepared polyamide material possesses high transparency and excellent UV aging resistance.

[0012] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a UV-resistant transparent polyamide material, wherein the UV-resistant transparent polyamide material is prepared from a diamine and a diacid; Based on the total molar number of diamines being 100%, the molar content of dialicyclic diamines in the diamines is 85%~98%, and the molar content of monoalicyclic diamines is 2%~15%. Based on the total molar number of dicarboxylic acids as 100%, the molar content of alicyclic dicarboxylic acids in the dicarboxylic acids is 1-10%, and the molar content of aliphatic dicarboxylic acids is 90-99%.

[0013] Preferably, the dialicyclic diamine is one or a combination of two or more of 4,4'-diaminodicyclohexylmethane (PACM), 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM), and 2,2-bis-(4-aminocyclohexyl)propane (PACP); the monoalicyclic diamine is one or a combination of two of 1-methyl-2,6-cyclohexanediamine (HTDA) and 1,4-cyclohexanediamine. Preferably, the alicyclic dicarboxylic acid is one or a combination of two or more of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid (CHDCA); the linear alicyclic dicarboxylic acid is one or a combination of two or more of adipic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, and tridecanoic acid.

[0014] Preferably, the relative viscosity of the UV-resistant transparent polyamide material is between 2.1 and 3.5; The light transmittance is maintained at 90.8%~91.8%; The light transmittance after UV irradiation is not less than 88.7%; The tensile strength is 61.4~79.5MPa.

[0015] As a second aspect of the invention, the present invention discloses a method for preparing the aforementioned UV-resistant transparent polyamide material, comprising the following steps: (1) Mix the dicarboxylic acid, diamine, catalyst, antioxidant and water and put them into the reaction vessel. Inert gas is introduced to replace the oxygen in the vessel. The reaction vessel is sealed and kept at 210-240℃ and 2.0-2.4MPa for 0.5-2h to complete the first high-pressure reaction stage. (2) After the first high-pressure reaction stage is completed, open the drain and exhaust valve to remove the water in the polymerization reactor and reduce the pressure of the reaction system to atmospheric pressure. At the same time, raise the temperature of the reaction system to 260-280℃. The drain and exhaust time is 1.5-3h to complete the second pressure reduction and drainage stage. (3) After the second depressurization and drainage stage is completed, the third negative pressure stage is completed by polymerization at 260-280℃ for 0.5-1.5h under negative pressure. After the reaction is completed, inert gas is introduced to 0.5MPa and the material is allowed to stand and discharged. After cooling in a water bath, the material is granulated to obtain the UV-resistant transparent polyamide material.

[0016] Preferably, in step (1), the catalyst is one or a combination of two or more of phosphorous acid, sodium hypophosphite, triphenyl phosphate, and H10, and the amount of catalyst used is 0.1 to 0.6% of the total weight of the dicarboxylic acid and diamine, preferably 0.2%.

[0017] Preferably, in step (1), the antioxidant is one or a combination of two or more of sodium hypophosphite, antioxidant 1010, antioxidant S9228, antioxidant SH120, antioxidant B215, antioxidant 136, antioxidant 1098, antioxidant 168, magnesium hypophosphite, calcium hypophosphite, or zinc hypophosphite; the amount of antioxidant used is 0.1-0.5% of the total weight of the diacid and diamine, preferably 0.2%.

[0018] Preferably, in step (1), the molar ratio of the diamine to the dicarboxylic acid is 0.96-1.04:1.

[0019] Preferably, in step (1), the water is deionized water, and the amount of deionized water added is 10-100% of the total weight of the dicarboxylic acid and diamine.

[0020] Preferably, in step (1), the inert gas is one or a combination of two or more of nitrogen, carbon dioxide, argon, and helium.

[0021] In this invention, by introducing rigid structures of alicyclic diamines and alicyclic diacids, on the one hand, the polyamide material is given better mechanical properties. The increased proportion of rigid rings disrupts the regularity of the molecular chain, hinders the crystallization of the molecular chain, and improves the transparency of the polyamide material. On the other hand, the introduction of alicyclic structures reduces the presence of ultraviolet absorbing groups in the molecular structure. At the same time, the introduction of HTDA monomers reduces the presence of terminal amine groups, thereby reducing the active sites for ultraviolet photooxidation.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a UV-resistant transparent polyamide material without added light stabilizers and its preparation method. The raw materials for preparing the polyamide material include alicyclic diamines, alicyclic diacids, and alicyclic diacids. Through screening specific raw materials, especially the selection of alicyclic diamines and the introduction of alicyclic diacids, and by screening their contents, the prepared polyamide material exhibits UV resistance, high transparency, and good mechanical properties. Specifically, the polyamide backbone constructed from alicyclic monomers does not contain aromatic ring conjugated structures, resulting in weak UV absorption and reducing UV-induced photo-oxidation reactions. Simultaneously, by introducing HTDA diamines to control the molecular chain end groups, the content of terminal amine groups in the system is effectively reduced, decreasing the possibility of imine and conjugated color-developing structures formed during photo-oxidation, thereby reducing the material's yellowing tendency and improving its stability under UV conditions. Through the above structural design, the resulting transparent polyamide material has excellent comprehensive performance, with a transparency of 90%~92% and a tensile strength of 60MPa~80MPa. After 600 hours of UV irradiation, its transparency can still be maintained above 88%, and it is not easy to yellow significantly under UV irradiation. The material has a high retention rate of optical and mechanical properties. Detailed Implementation

[0023] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] It should be noted that in the first high-pressure reaction stage of this invention, the material is kept at a constant temperature and pressure in a high-temperature and high-pressure polymerization reactor for 0.5h to 2h. Specifically, after the temperature is raised to the target temperature of 210℃ to 240℃, the pressure inside the system reaches 2.0MPa to 2.4MPa, and then the temperature and pressure are maintained for 0.5h to 2h to ensure that the composition is constant and to further increase its molecular weight. The purpose of using a negative pressure polymerization reaction stage in the later stage of this invention is to further prepare high-viscosity, UV-resistant, transparent polyamide.

[0025] Example 1:

[0026] This embodiment is a UV-resistant transparent polyamide PAPACMC / PACM12 / PAHC / PAH12, prepared from a diamine and a diacid. Based on the total molar amount of the diamine (100%), the diamine contains 98% dialicyclic diamine and 2% monoalicyclic diamine. Based on the total molar amount of the diacid (100%), the diacid contains 1% ...

[0027] Its preparation method includes a first high-pressure reaction stage, a second pressure reduction and drainage stage, and a third negative pressure stage, specifically including the following steps: (1) Weigh the following materials according to a certain ratio: 587.76g of 4,4'-diaminodicyclohexylmethane (PACM), 7.31g of 1-methyl-2,6-cyclohexanediamine (HTDA), 637.56g of dodecanoic acid, 4.816g of 1,4-cyclohexanedicarboxylic acid (1,4-CHDCA), 1237.55g of deionized water, and the mass of sodium hypophosphite is 0.2% of the total weight of the dicarboxylic acid and diamine; put the proportioned materials into a high-temperature and high-pressure polymerization reactor, replace the gas with nitrogen three times, heat to 220℃, pressure of 2.2MPa, keep warm and pressurized for 1h to complete the first high-pressure reaction stage; (2) After the first high-pressure reaction stage is completed, open the drain and exhaust valve, slowly remove the water in the polymerization reactor, reduce the pressure of the reaction system to atmospheric pressure, and at the same time raise the temperature of the reaction system to 260°C. The drain and exhaust time is 2 hours, and the second pressure reduction and drainage stage is completed. (3) After the second pressure reduction and drainage stage is completed, the third negative pressure stage is completed by polymerization at 260°C for 1 hour under negative pressure of -0.09MPa. After the reaction is completed, an inert gas pressure of 0.5MPa is introduced and the material is allowed to stand and discharged. After cooling in a water bath, the material is granulated to obtain the UV-resistant transparent polyamide material.

[0028] Example 2:

[0029] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 1, except that the proportions of the raw materials are different. In this embodiment, based on the total molar amount of diamines as 100%, the molar content of dialicyclic diamines is 94%, and the molar content of monoalicyclic diamines is 6%. Based on the total molar amount of diacids as 100%, the molar content of 1,4-alicyclic diacids is 10%, and the molar content of linear aliphatic diacids is 90%. The molar ratio of the diamine to the diacid is 1.02:1. Specifically, the amounts of each raw material are as follows: 563.77 g of 4,4'-diaminodicyclohexylmethane (PACM), 21.93 g of 1-methyl-2,6-cyclohexanediamine (HTDA), 579.60 g of dodecanoic acid, 48.16 g of 1,4-cyclohexanedicarboxylic acid (1,4-CHDCA), 1213.46 g of deionized water, and 0.2% of the total weight of sodium hypophosphite and dicarboxylic acid and diamine.

[0030] Example 3:

[0031] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 1, except that the proportions of the raw materials are different. In this embodiment, the total molar amount of diamine is 100%, and the molar content of dialicyclic diamine is 90%, while the molar content of monoalicyclic diamine is 10%. Similarly, the total molar amount of diacid is 100%, and the molar content of 1,4-alicyclic diacid is 5%, while the molar content of linear aliphatic diacid is 95%. The molar ratio of the diamine to the diacid is 1.02:1.

[0032] Specifically, in this embodiment, the amounts of each raw material are as follows: 539.78 g of 4,4'-diaminodicyclohexylmethane (PACM), 36.56 g of 1-methyl-2,6-cyclohexanediamine (HTDA), 611.8 g of dodecanoic acid, 24.08 g of 1,4-cyclohexanedicarboxylic acid (1,4-CHDCA), 1212.22 g of deionized water, and 0.2% of the total weight of sodium hypophosphite and dicarboxylic acid and diamine.

[0033] Example 4:

[0034] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 1, except that the proportions of the raw materials are different. In this embodiment, the total molar amount of diamine is 100%, and the molar content of dialicyclic diamine is 85%, while the molar content of monoalicyclic diamine is 15%. Similarly, the total molar amount of diacid is 100%, and the molar content of 1,4-alicyclic diacid is 10%, while the molar content of linear aliphatic diacid is 90%. The molar ratio of diamine to diacid is 1.02:1.

[0035] Specifically, the amounts of each raw material used in this embodiment are as follows: 509.79 g of 4,4'-diaminodicyclohexylmethane (PACM), 54.84 g of 1-methyl-2,6-cyclohexanediamine (HTDA), 579.60 g of dodecanoic acid, 48.16 g of 1,4-cyclohexanediamine (1,4-CHDCA), 1192.39 g of deionized water, and 0.2% of the total weight of sodium hypophosphite and dicarboxylic acid and diamine.

[0036] Example 5

[0037] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the molar ratio of the diamine to the diacid is 0.96:1.

[0038] Example 6

[0039] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the molar ratio of the diamine to the diacid is 1:1.

[0040] Example 7

[0041] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the molar ratio of the diamine to the diacid is 1.04:1.

[0042] Example 8:

[0043] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the heat preservation temperature of the first high-pressure reaction stage is 210°C.

[0044] Example 9:

[0045] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the heat preservation temperature of the first high-pressure reaction stage is 240°C.

[0046] Example 10:

[0047] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the holding pressure in the first high-pressure reaction stage is 2.0 MPa.

[0048] Example 11:

[0049] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the holding pressure in the first high-pressure reaction stage is 2.4 MPa.

[0050] Example 12:

[0051] The difference between the UV-resistant transparent polyamide and its preparation method in this embodiment and those in Example 2 is that the pressure holding time in the first high-pressure reaction stage is 0.5 h.

[0052] Example 13:

[0053] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2, except that the pressure holding time in the first high-pressure reaction stage is 2 hours.

[0054] Example 14:

[0055] The difference between the UV-resistant transparent polyamide and its preparation method in this embodiment and those in Embodiment 2 is that the temperature of the reaction system is increased to 270°C in the second depressurization and drainage reaction stage.

[0056] Example 15:

[0057] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2. The difference between Example 2 and Example 2 is that the temperature of the reaction system in the second pressure reduction and drainage reaction stage is increased to 280°C.

[0058] Example 16:

[0059] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2. The difference between Example 2 and Example 2 is that the exhaust time of the reaction system in the second pressure reduction and drainage reaction stage is 1.5h.

[0060] Example 17:

[0061] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2. The difference between Example 2 and Example 2 is that the exhaust time of the reaction system in the second pressure reduction and drainage reaction stage is 3 hours.

[0062] Example 18:

[0063] The difference between the UV-resistant transparent polyamide and its preparation method in this embodiment and those in Embodiment 2 is that the reaction time of the system in the third negative pressure reaction stage is 0.5 h.

[0064] Example 19:

[0065] The UV-resistant transparent polyamide and its preparation method in this embodiment are the same as in Example 2. The difference between Example 2 and Example 2 is that the reaction time of the system in the third negative pressure reaction stage is 1.5h.

[0066] Comparative Example 1:

[0067] The preparation method of the UV-resistant transparent polyamide in Comparative Example 1 differs from that in Example 2 in that the amounts of each raw material are different. In this comparative example, 1-methyl-2,6-cyclohexanediamine (HTDA) is not added. The amounts of each raw material in this comparative example are: 656.88 g of 4,4'-diaminodicyclohexylmethane (PACM), 579.60 g of dodecanoic acid, 48.16 g of 1,4-cyclohexanediamine (1,4-CHDCA), 1284.64 g of deionized water, and 0.2% of the total weight of sodium hypophosphite and diamine. Other process parameters are the same as in Example 2.

[0068] Comparative Example 2:

[0069] The polyamide and its preparation method in Comparative Example 2 differ from those in Example 2 in that the amounts of each raw material are different. In this comparative example, the amounts of each raw material are as follows: 4,4'-diaminodicyclohexylmethane (PACM) 479.81 g, 1-methyl-2,6-cyclohexanediamine (HTDA) 73.11 g, dodecanoic acid 579.60 g, 1,4-cyclohexanediamine (1,4-CHDCA) 48.16 g, deionized water 1180.68 g, and sodium hypophosphite 0.2% of the total weight of the dicarboxylic acid and diamine. Other process parameters are the same as in Example 2.

[0070] Comparative Example 3

[0071] The polyamide and its preparation method in Comparative Example 3 differ from those in Example 2 in that the molar ratio of the diamine to the diacid is 1.06:1, while other process parameters are the same as in Example 2.

[0072] Comparative Example 4:

[0073] The polyamide and its preparation method in Comparative Example 4 differ from those in Example 2 in that the first high-pressure reaction stage is kept at a temperature of 200°C, while other process parameters and the amount of each raw material are the same as in Example 2.

[0074] Comparative Example 5:

[0075] The polyamide and its preparation method in Comparative Example 5 differ from those in Example 2 in that the heat preservation and pressure holding time in the first high-pressure reaction stage is 0h, while other process parameters and the amount of each raw material are the same as in Example 2.

[0076] Comparative Example 6:

[0077] The polyamide and its preparation method in Comparative Example 6 differ from those in Example 2 in that the temperature of the reaction system in the second depressurization and drainage reaction stage is increased to 250°C, while other process parameters and the amount of each raw material are the same as in Example 2.

[0078] Comparative Example 7

[0079] The polyamide and its preparation method in Comparative Example 7 differ from those in Example 2 in that the exhaust time of the reaction system in the second pressure reduction and drainage reaction stage is 1 hour, while other process parameters and the amount of each raw material are the same as in Example 2.

[0080] Comparative Example 8

[0081] The polyamide and its preparation method in Comparative Example 8 differ from those in Example 2 in that the reaction time under negative pressure in the third negative pressure reaction stage is 10 min, while other process parameters and the amount of each raw material are the same as in Example 2.

[0082] The polyamide materials provided in Examples 1-19 and Comparative Examples 1-8 were subjected to performance tests, and the test methods are as follows: Relative viscosity: The relative viscosity was tested according to the viscosity test standard GB / T10247-2008: using 98% concentrated sulfuric acid as solvent, 0.25 g of sample was weighed and a polymer solution with a concentration of 1 g / dL was prepared in a 25 mL volumetric flask. After the polymer was completely dissolved, the viscosity was tested in a constant temperature water bath at 25 ℃ using an Ubbelohde viscometer with a diameter of 0.9-1 mm.

[0083] Tensile strength: Dumbbell-shaped specimens with dimensions of 170mm×10mm×4mm were prepared by injection molding. Tensile properties were tested using a CMT5104 universal testing machine, referring to the national standard GB / T 1040.2-2006, with a tensile rate of 20mm / min.

[0084] Notched impact strength: Specimens were prepared by injection molding, with dimensions of 75mm × 10mm × 4mm. Notched impact performance was tested using a SANS pendulum impact testing machine with a V-notch and a 2mm notch.

[0085] Transmittance: A transparent thin film sample with a thickness of 2 mm was obtained by lamination and tested using a WGT-S transmittance / haze meter.

[0086] Yellowness: Transparent thin film samples with a thickness of 2 mm were obtained by lamination, and the yellowness index of the thin film samples was evaluated using a 3nh spectrophotometer.

[0087] UV irradiation: Using a UVA lamp (Atlas) with a main wavelength of 340 nm (radiation distribution in the range of 300-400 nm), an ultraviolet weathering test chamber was used, and the ultraviolet irradiation intensity was set to approximately 0.48 W / m². The PA polymer was irradiated for 600 hours to simulate atmospheric aging.

[0088] Examples 1-4 and Comparative Examples 1-2 reflect the influence of HTDA monomer and CHDCA monomer content on product performance. The test results are shown in Table 1 below.

[0089] Table 1 Properties of the transparent nylon polymers obtained in Examples 1-4 and Comparative Examples 1 and 2 Table 1 illustrates the effect of adjusting the HTDA content in UV-resistant transparent polyamides on their properties. The results show that as the HTDA content increases, the polymerization of the product becomes more difficult, and the viscosity decreases with increasing HTDA content. When the HTDA content is less than 20%, the UV-resistant transparent polyamide maintains good transparency after UV irradiation. Compared to transparent polyamides without HTDA monomer, UV-resistant transparent nylons with HTDA monomer exhibit better transparency retention.

[0090] Examples 2, 5-7, and Comparative Example 3 reflect the effect of the molar ratio of diamine to diacid on the product performance. The test results are shown in Table 2 below.

[0091] Table 2 Properties of the transparent nylon polymers obtained in Examples 2, 5-7 and Comparative Example 3 Table 2 illustrates the effect of adjusting the molar ratio of diamine to diacid in UV-resistant transparent polyamide on the polyamide's properties, as shown in Examples 2, 5-7, and Comparative Example 3. The results show that when the diacid is in excess, the polymerization reaction is limited, resulting in a product with lower relative viscosity and mechanical properties. When the diamine is in moderate excess, its volatility allows the acid-amine ratio in the system to approach 1:1 in practice, which is beneficial for the polymerization reaction and helps maintain the product's superior properties. Therefore, the preferred molar ratio of diamine to diacid in this invention is 0.96-1.04:1.

[0092] Examples 8 and 9, as well as Comparative Example 4, reflect the effect of heat preservation temperature on product performance. The test results are shown in Table 3 below.

[0093] Table 3 Properties of the transparent nylon polymers obtained in Examples 8, 9 and Comparative Example 4 Table 3 illustrates the effect of adjusting the holding temperature of the first high-pressure reaction stage on the properties of the obtained transparent UV-resistant polyamide. The results show that as the holding temperature of the first high-pressure reaction stage decreases, the mechanical and optical properties of the obtained transparent nylon product decrease, and the transparency retention rate after UV irradiation decreases. As the holding temperature of the first high-pressure reaction stage increases, the various properties of the prepared transparent UV-resistant polyamide do not change much and can meet the performance requirements of UV-resistant transparent polyamide.

[0094] Examples 2, 10, and 11 reflect the effect of holding pressure on product performance, and the test results are shown in Table 4 below.

[0095] Table 4 Properties of the transparent nylon polymers obtained in Examples 2, 10, and 11 Table 4 Examples 2, 10, and 11 illustrate the effect of adjusting the holding pressure in the first high-pressure reaction stage on the properties of the obtained UV-resistant transparent polyamide. The results show that as the holding pressure decreases, the mechanical properties of the prepared UV-resistant transparent polyamide will decrease, but the optical properties can meet the performance requirements of the product, and it can maintain high transparency after UV irradiation.

[0096] Examples 12-15 and Comparative Examples 5 and 6 reflect the effects of heat preservation and pressure holding time and different final polymerization temperatures on the product properties. The test results are shown in Table 5 below.

[0097] Table 5 Properties of the transparent nylon polymers obtained in Examples 12-15 and Comparative Examples 5 and 6 To illustrate the effects of process conditions such as the holding time in the first high-pressure reaction stage and the reaction system temperature in the second depressurization and drainage stage on the properties of UV-resistant transparent polyamide, a comparative study was conducted using Examples 12-15 and Comparative Examples 5 and 6 to investigate different holding times and reaction system temperatures during the preparation process. The results show that shortening the holding time in the first high-pressure reaction stage or lowering the reaction system temperature in the second depressurization and drainage stage is detrimental to increasing the relative viscosity of the polymer and also affects the transparency of the resulting polyamide material, with a more significant decrease in transparency after UV irradiation.

[0098] Examples 16-19 and Comparative Examples 7 and 8 reflect the effects of different exhaust times and negative pressure times on product performance. The test results are shown in Table 6 below.

[0099] Table 6 Properties of the transparent nylon polymers obtained in Examples 16-19 and Comparative Examples 7 and 8 Examples 16-19 and Comparative Examples 7 and 8 illustrate the effects of adjusting the venting time of the second depressurization drainage stage and the reaction time of the third negative pressure reaction stage on polymer properties. The results show that when the venting time is too short, water vapor and by-products remain, which is not conducive to increasing the relative viscosity of the polymer. When the negative pressure reaction time is short, the relative viscosity of the polymer does not increase much, and the mechanical properties of the resulting product are reduced. As the negative pressure reaction time increases, it becomes too difficult to discharge the reaction product, which is not conducive to the subsequent processing of the product.

[0100] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A UV-resistant transparent polyamide material, characterized in that, The UV-resistant transparent polyamide material is prepared from diamine and diacid; Based on the total molar number of diamines being 100%, the molar content of dialicyclic diamines in the diamines is 85%~98%, and the molar content of monoalicyclic diamines is 2%~15%. Based on the total molar number of dicarboxylic acids as 100%, the molar content of alicyclic dicarboxylic acids in the dicarboxylic acids is 1-10%, and the molar content of linear aliphatic dicarboxylic acids is 90-99%.

2. The UV-resistant transparent polyamide material according to claim 1, characterized in that, The dialicyclic diamine is one or a combination of two or more of 4,4'-diaminodicyclohexylmethane (PACM), 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM), and 2,2-bis-(4-aminocyclohexyl)propane (PACP); the monoalicyclic diamine is one or a combination of two of 1-methyl-2,6-cyclohexanediamine (HTDA) and 1,4-cyclohexanediamine. The alicyclic dicarboxylic acid is one or a combination of two or more of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid (CHDCA); the linear alicyclic dicarboxylic acid is one or a combination of two or more of adipic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, and tridecanoic acid.

3. The UV-resistant transparent polyamide material according to claim 1, characterized in that, The relative viscosity of the UV-resistant transparent polyamide material is between 2.1 and 3.

5. The light transmittance is maintained at 90.8%~91.8%; The light transmittance after UV irradiation is not less than 88.7%; The tensile strength is 61.4~79.5MPa.

4. A method for preparing a UV-resistant transparent polyamide material as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Mix the dicarboxylic acid, diamine, catalyst, antioxidant and water and put them into the reaction vessel. Inert gas is introduced to replace the oxygen in the vessel. The reaction vessel is sealed and kept at 210-240℃ and 2.0-2.4MPa for 0.5-2h to complete the first high-pressure reaction stage. (2) After the first high-pressure reaction stage is completed, open the drain and exhaust valve to remove the water in the polymerization reactor and reduce the pressure of the reaction system to atmospheric pressure. At the same time, raise the temperature of the reaction system to 260-280℃. The drain and exhaust time is 1.5-3h to complete the second pressure reduction and drainage stage. (3) After the second depressurization and drainage stage is completed, the third negative pressure stage is completed by polymerization at 260-280℃ for 0.5-1.5h under negative pressure. After the reaction is completed, inert gas is introduced to 0.5MPa and the material is allowed to stand and discharged. After cooling in a water bath, the material is granulated to obtain the UV-resistant transparent polyamide material.

5. The method for preparing the UV-resistant transparent polyamide material according to claim 4, characterized in that, In step (1), the catalyst is one or a combination of two or more of phosphorous acid, sodium hypophosphite, triphenyl phosphate, and H10, and the amount of catalyst used is 0.1 to 0.6% of the total weight of the diacid and diamine; the antioxidant is one or a combination of two or more of sodium hypophosphite, antioxidant 1010, antioxidant S9228, antioxidant SH120, antioxidant B215, antioxidant 136, antioxidant 1098, antioxidant 168, magnesium hypophosphite, calcium hypophosphite, or zinc hypophosphite; the amount of antioxidant used is 0.1 to 0.5% of the total weight of the diacid and diamine.

6. The method for preparing the UV-resistant transparent polyamide material according to claim 4, characterized in that, In step (1), the molar ratio of the diamine to the dicarboxylic acid is 0.96-1.04:

1.

7. The method for preparing the UV-resistant transparent polyamide material according to claim 4, characterized in that, In step (1), the water is deionized water, and the amount of deionized water added is 10-100% of the total weight of the dicarboxylic acid and diamine.

8. The method for preparing the UV-resistant transparent polyamide material according to claim 4, characterized in that, In step (1), the inert gas is one or a combination of two or more of nitrogen, carbon dioxide, argon and helium.