A polyamide and a method for its preparation and use

Abstract

The application provides a kind of polyamide and its preparation method and application, the polyamide includes diamin residue and diacid residue;The diamin residue includes bis (4-aminocyclohexyl) methane residue and bis (3-methyl-4-aminocyclohexyl) methane residue;The diacid residue includes 1,12-dodecanedioic acid residue;In the gas chromatogram of the polyamide, the peak area of the first main peak is recorded as S1;The peak area of the fourth main peak is recorded as S4;R=S1 / S4, R≥1.79.The polyamide has high flexural modulus, and can meet the application requirements of thin-walled AR glasses frame.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polyamide, its preparation method, and its application. Background Technology

[0002] Transparent polyamides are widely used in the eyewear industry due to their excellent optical properties and temperature resistance. Typically, transparent polyamides achieve their superior transparency (transmittance > 90%) by introducing alicyclic rings or alicyclic diamines (such as bis(3-methyl-4-aminocyclohexyl)methane, MACM) to disrupt the regularity of the molecular chain. Therefore, alicyclic diamines are a key monomer in the synthesis of transparent polyamides, and their structural characteristics are crucial to the material's properties. Industrially commonly used diamines of this type typically consist of two cyclohexane rings connected by an alkylene bridge, with an amino group bonded to each ring, and may also contain alkyl substituents. This unique chemical structure leads to complex stereoisomerism. The diversity of isomers stems primarily from three aspects: first, the substituents on the cyclohexane ring can adopt axial or equatorial spatial orientations; second, these substituents can form cis or trans stereoisomers relative to the alkylene bridge connecting the two rings; and third, the two cyclohexane rings themselves possess conformational flexibility. These factors collectively result in the coexistence of multiple stereoisomers. Therefore, the alicyclic diamine raw materials actually used are usually mixtures of various stereoisomers. However, different isomers differ in reactivity, steric hindrance, etc., which directly affect the polymerization process, polymer chain regularity, and ultimately the optical, thermal, and mechanical properties of transparent polyamides.

[0003] As consumers increasingly demand greater comfort and aesthetics from eyeglasses, AR eyeglass frames are evolving towards being "lighter, thinner, and more durable." Thin-walled design is a crucial way to achieve weight reduction, but this requires materials with higher modulus (rigidity) to maintain the frame's shape and prevent breakage, while also ensuring good transparency. However, conventional eyeglass frame materials, such as transparent polyamide, have a lower flexural modulus and cannot fully meet the requirements of thin-walled design. This can lead to excessive elastic deformation due to lens weight or head pressure during wear, affecting stability and comfort.

[0004] Therefore, developing a polyamide with high flexural modulus to meet the application requirements of thin-walled AR glasses frames is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a polyamide, its preparation method, and its applications. The polyamide possesses a high flexural modulus, which meets the application requirements of thin-walled AR glasses frames.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polyamide comprising a diamine residue and a diacid residue; the diamine residue comprising bis(4-aminocyclohexyl)methane (PACM) residue and bis(3-methyl-4-aminocyclohexyl)methane (MACM) residue; the diacid residue comprising 1,12-dodecyl diacid residue; in the gas chromatogram of the polyamide, the peak area of ​​the first main peak is denoted as S1; the peak area of ​​the fourth main peak is denoted as S4; R=S1 / S4, R≥1.79; the first main peak is the chromatographic peak of isomer A1 of the bis(4-aminocyclohexyl)methane residue; the fourth main peak is the chromatographic peak of isomer B1 of the bis(3-methyl-4-aminocyclohexyl)methane residue.

[0007] In this invention, a specific composition of diamine residues and diacid residues is used in combination, and the ratio R of isomer A1 in bis(4-aminocyclohexyl)methane residues to isomer B1 in bis(3-methyl-4-aminocyclohexyl)methane residues is controlled to be ≥1.79, which is beneficial to improve the flexural modulus of polyamide. At the same time, by further adjusting R within a specific range, the good temperature resistance, processing performance and light transmittance of polyamide can also be guaranteed, so that the polyamide meets the application requirements of thin-walled AR glasses frames.

[0008] In this invention, R ≥ 1.79 can be, for example, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.7, 3.8, 3.9, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9 or any of the above values, more preferably R ≥ 3.5, and particularly preferably R is 4.4 to 8.

[0009] In this invention, the R value is relatively small (<1.79), which reduces the flexural modulus of the polyamide. Considering the temperature resistance and light transmittance of the polyamide, the R value should not be too high either, as a high R value will lead to a decrease in the glass transition temperature and slightly poorer temperature resistance.

[0010] In this invention, the R value can be obtained by adjusting the types (i.e., using diamine raw materials with different contents of isomer A1 or isomer B1) and contents of the diamine monomers bis(4-aminocyclohexyl)methane and bis(3-methyl-4-aminocyclohexyl)methane, as well as the polymerization process (e.g., polymerization temperature).

[0011] It should be noted that PACM, as is well known to those skilled in the art, has three stereoisomers. In the gas chromatogram of PACM, three peaks will appear according to the order of appearance of the chromatographic column. The isomer corresponding to the first main elution peak is the isomer A1 described in this invention. MACM has at least 16 stereoisomers. In the gas chromatogram of MACM, six peaks will appear according to the order of appearance of the chromatographic column. The isomer corresponding to the first main elution peak is the isomer B1 described in this invention.

[0012] In this invention, the bis(4-aminocyclohexyl)methane residues are derived from bis(4-aminocyclohexyl)methane, and the first main peak in the gas chromatogram of the bis(4-aminocyclohexyl)methane is the chromatographic peak of isomer A1; the molar percentage of isomer A1 in the bis(4-aminocyclohexyl)methane is 19-51%, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or any of the above values, more preferably 25-43%.

[0013] In this invention, the molar percentage of isomer A1 in bis(4-aminocyclohexyl)methane is calculated as 100% of the total molar content of bis(4-aminocyclohexyl)methane monomer.

[0014] Preferably, the bis(3-methyl-4-aminocyclohexyl)methane residues are derived from bis(3-methyl-4-aminocyclohexyl)methane, and the first main peak in the gas chromatogram of the bis(3-methyl-4-aminocyclohexyl)methane is the chromatographic peak of isomer B1; the molar percentage of isomer B1 in the bis(3-methyl-4-aminocyclohexyl)methane is 28-40%, for example, it can be 29%, 30%, 31%, 32%, 33%, 34%, 36%, 37%, 38%, 39% or any of the above values, more preferably 29-32%.

[0015] It should be noted that this invention only considers the first five main peaks in the gas chromatogram of bis(3-methyl-4-aminocyclohexyl)methane, that is, in order of appearance, they are the first main peak, the second main peak, the third main peak, the fourth main peak, and the fifth main peak. The other peaks are peaks of isomers with extremely low content, which have little to no impact on performance and are therefore not considered. The molar percentage of isomer B1 in bis(3-methyl-4-aminocyclohexyl)methane is calculated as the total molar content of the isomers corresponding to the first, second, third, fourth, and fifth main peaks being 100%.

[0016] In this invention, based on a total molar amount of 100 mol% of diamine residues, the molar percentage of bis(4-aminocyclohexyl)methane residues is 73.5~86.5 mol%, for example, it can be 74 mol%, 74.5 mol%, 75 mol%, 75.5 mol%, 76 mol%, 76.5 mol%, 77 mol%, 77.5 mol%, 78 mol%, 78.5 mol%, 79 mol%, 79.5 mol%, 80 mol%, 80.5 mol%, 81 mol%, 81.5 mol%, 82 mol%, 82.5 mol%, 83 mol%, 83.5 mol%, 84 mol%, 84.5 mol%, 85 mol%, 85.5 mol%, 86 mol%, or any of the above values, more preferably 76~85.5 mol%.

[0017] In this invention, based on a total molar amount of 100 mol% of diamine residues, the molar percentage of bis(3-methyl-4-aminocyclohexyl)methane residues is 13.5 to 26.5 mol%, for example, it can be 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, or any of the above values.

[0018] In this invention, the diacid residue may also include other diacid residues, which may be other aliphatic diacid residues, such as 1,14-tetradecyl diacid residues, 1,16-hexadecyl diacid residues, 1,18-octadecyl diacid residues, etc.; or they may be aromatic diacid residues, such as terephthalic acid residues, isophthalic acid residues, furanyl diacid residues, etc.; when the diacid residue includes other diacid residues, the molar percentage of 1,12-dodecyl diacid residue in the diacid residue is ≥50 mol%, more preferably ≥80 mol%.

[0019] In this invention, the molar ratio of the diamine residue to the dicarboxylic acid residue is 1:1.

[0020] It should be noted that the term "residue" refers to any organic structure introduced into the polymer molecular chain by the relevant monomer through a polycondensation reaction, that is, an organic structure derived from the relevant monomer; for example, a diacid residue refers to a structure in polyamide derived from a diacid monomer.

[0021] In this invention, the glass transition temperature of the polyamide is 135~155℃, for example, it can be 136℃, 138℃, 140℃, 142℃, 144℃, 146℃, 148℃, 150℃, 152℃, 154℃ or any range between the above values.

[0022] In this invention, the modulus of the polyamide is ≥1800MPa, more preferably 2000~2162MPa.

[0023] In this invention, the polyamide has a light transmittance of ≥84% and a haze of ≤0.7%.

[0024] In a second aspect, the present invention provides a method for preparing polyamide according to the first aspect, the method comprising the following steps: mixing a diacid with a diamine and performing a gradient heating reaction to obtain the polyamide.

[0025] Preferably, the mixed material further includes at least one of a solvent, a capping agent, a catalyst, and an antioxidant.

[0026] In this invention, the solvent includes, but is not limited to, water; the mass of the solvent is 20-40% of the total mass of the feed, for example, it can be 25%, 30%, 35% or any of the above values.

[0027] In this invention, the total mass of the feed refers to the total mass of all substances, including the solvent, namely the total mass of the dicarboxylic acid, diamine, and optionally the solvent, capping agent, catalyst, and antioxidant.

[0028] In this invention, the capping agent includes a monobasic acid, such as stearic acid or benzoic acid; the molar content of the capping agent is 1 to 5% of the total molar content of the dibasic acid and diamine, for example, it can be 2%, 3%, 4% or any of the above values.

[0029] In this invention, the catalyst comprises sodium hypophosphite; the mass of the catalyst is 0.05 to 0.15% of the total mass of the feed other than the solvent, for example, it can be 0.06%, 0.08%, 0.1%, 0.12%, 0.14% or any of the above values.

[0030] In this invention, the antioxidant includes a primary antioxidant and / or a secondary antioxidant; the primary antioxidant includes, but is not limited to, 2,6-di-tert-butyl-p-cresol (BHT), 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis(4-methyl-6-nonylphenol), 3-(3,5-di-butyl-p-cresol), and 2,2'-di-tert-butyl-p-cresol. -Octadecanyl di-tert-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) ester; the auxiliary antioxidant includes, but is not limited to, tri(nonylphenyl) phosphite and / or dilauryl thiodipropionate.

[0031] In this invention, the mass of the antioxidant is 0.1 to 0.3% of the total mass of the other ingredients excluding the solvent, for example, it can be 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28% or any range of the above values.

[0032] Preferably, the gradient heating reaction includes a first-stage reaction, a second-stage reaction, and a third-stage reaction performed sequentially.

[0033] In this invention, the reaction is carried out in the presence of a protective atmosphere; the protective atmosphere includes, but is not limited to, nitrogen.

[0034] Preferably, the temperature of the first stage reaction is 180~200℃, for example, it can be 185℃, 190℃, 195℃ or any of the above values; the time is 0.5~2h, for example, it can be 1h, 1.5h or any of the above values.

[0035] Preferably, the temperature of the second stage reaction is 240~260℃, for example, 245℃, 250℃, 255℃ or any of the above values; the pressure is 2~3MPa, for example, 2.2 MPa, 2.4 MPa, 2.6 MPa; and the time is 0.5~2h, for example, 1h, 1.5h or any of the above values.

[0036] In this invention, the second stage reaction is followed by a step of depressurizing to atmospheric pressure by removing the formed water.

[0037] Preferably, the temperature of the third-stage reaction is 260~290℃, for example, 265℃, 270℃, 275℃ or any of the above values; the pressure is 30~70Pa, for example, 35 Pa, 40 Pa, 45 Pa, 50 Pa, 55 Pa, 60 Pa, 65 Pa or any of the above values; and the time is 1~4h, for example, 1.5h, 2h, 2.5h, 3h, 3.5h or any of the above values.

[0038] Thirdly, the present invention provides a polyamide resin composition comprising the polyamide described in the first aspect.

[0039] In this invention, polyamide can be compounded with other components to form a polyamide resin composition according to actual needs, thereby meeting different performance requirements.

[0040] In this invention, the polyamide resin composition contains ≥50% polyamide by mass.

[0041] Preferably, the other components include fillers and / or additives.

[0042] In this invention, the filler content in the polyamide resin composition is ≤50% by mass; the additive content in the polyamide resin composition is ≤10% by mass.

[0043] In this invention, the filler includes, but is not limited to, at least one of silica, kaolin, calcium carbonate, talc, montmorillonite, mica, wollastonite, glass fiber, and carbon fiber.

[0044] In this invention, the additives include, but are not limited to, at least one of lubricants, coupling agents, antioxidants, and light stabilizers.

[0045] In this invention, the lubricant includes, but is not limited to, at least one of polyethylene wax, polypropylene wax, paraffin wax, organosiloxane, silicone, and polytetrafluoroethylene.

[0046] In this invention, the coupling agent includes silane coupling agents, which include, but are not limited to, at least one of the following: aminosilane coupling agents (such as γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane), epoxysilane coupling agents (such as γ-glycidoxypropyltrimethoxysilane), vinylsilane coupling agents (such as vinyltriethoxysilane, vinyltrimethoxysilane), methacryloxysilane coupling agents (γ-methacryloxypropyltrimethoxysilane), and mercaptosilane coupling agents (such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane).

[0047] The antioxidants include primary antioxidants and / or secondary antioxidants; the primary antioxidants include, but are not limited to, N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine, 2,6-di-tert-butyl-p-cresol (BHT), 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol). The antioxidants include, but are not limited to, any one or a combination of at least two of the following: nonylphenol (-6-), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate); the auxiliary antioxidants include, but are not limited to, tri(nonylphenyl) phosphite and / or dilauryl thiodipropionate.

[0048] In this invention, the light stabilizer includes, but is not limited to, at least one of benzotriazole UV absorbers (such as UV-P, UV-327, UV-326), benzophenone UV absorbers (such as UV-531, UV-9), triazine UV absorbers (such as UV-1164, UV-400), and hindered amine light stabilizers (such as Chimassorb 944, Tinuvin 770, Tinuvin 622).

[0049] Fourthly, the present invention provides a high-modulus transparent article, the high-modulus transparent article comprising the polyamide described in the first aspect or the polyamide resin composition described in the third aspect.

[0050] In this invention, the high-modulus transparent products include, but are not limited to, AR glasses, children's glasses, ordinary optical glasses, sports goggles, etc.

[0051] In this invention, the thickness of the high-modulus transparent product is ≤4mm.

[0052] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows: The polyamide provided by this invention uses a specific composition of diamine residues and diacid residues, and controls the ratio R of isomer A1 in bis(4-aminocyclohexyl)methane residues to isomer B1 in bis(3-methyl-4-aminocyclohexyl)methane residues to be ≥1.79, which is beneficial to improving the flexural modulus of the polyamide. At the same time, by further adjusting R within a specific range, the polyamide can also be guaranteed to have good temperature resistance, processing performance and light transmittance, so that the polyamide meets the application requirements of thin-walled AR glasses frames. Attached Figure Description

[0054] Figure 1 This is a gas chromatogram of the polyamide provided in Example 8 of the present invention.

[0055] Figure 2 This is the gas chromatogram of the monomer MACM30 used in this invention. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] All materials used in this invention can be purchased commercially or prepared using conventional methods. Unless otherwise specified, the materials used in this invention are as follows.

[0058] Dicarboxylic acid 1,12-Dodecyl diacid: purchased from Inokai.

[0059] The specific sources of diamines are shown in Table 1; where molar percentage refers to the molar percentage of isomer A1 in PACM monomer and the molar percentage of isomer B1 in MACM monomer.

[0060] Table 1 1,4-Cyclohexanediamine: analytical grade, purchased from Inokai.

[0061] Benzoic acid: analytical grade, purchased from Sigma-Aldrich.

[0062] Sodium hypophosphite: analytical grade, purchased from Sigma-Aldrich.

[0063] Antioxidant 1098: analytical grade, purchased from Sigma-Aldrich.

[0064] Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0065] In this invention, the test methods for the composition of diamine residues in the polyamide, R value, molar percentage of isomer A1 in PACM monomer and molar percentage of isomer B1 in MACM monomer, glass transition temperature (Tg), and other related properties are as follows.

[0066] 1. Composition of diamine residues in polyamides In this invention, the composition of diamine residues in polyamide is calculated by the amount of diamine added. For example, the molar content of bis(4-aminocyclohexyl)methane residues in diamine residues is the proportion of bis(4-aminocyclohexyl)methane monomer in the total molar content of diamine monomers.

[0067] 2. Molar percentage of isomer A1 in PACM monomer and molar percentage of isomer B1 in MACM monomer Dissolve 0.5 g of the raw material in 20 mL of anhydrous ethanol. Perform gas chromatography analysis on the sample using an Agilent 7890B gas chromatograph (test conditions are as follows: column type: HP5MS, 30 m × 0.25 mm × 0.25 µm, 7-inch column holder; programmed temperature rise, column oven temperature: 80 °C for 1 min, then increase to 260 °C at a rate of 15 °C / min and hold for 5 min; injection port 280 °C, auxiliary heater 280 °C).

[0068] The peak retention times (min) of PACM are as follows: 9.905±0.005 (peak area S11: trans-trans, isomer A1), 9.987±0.005 (peak area S12: trans-cis, isomer A2), and 10.041±0.005 (peak area S13: cis-cis, isomer A3). The molar percentage of isomer A1 in PACM (R1) is calculated based on the peak area ratio, and the calculation formula is R1=S11 / (S11+S12+S13).

[0069] The peak retention times (min) of MACM are: 10.587±0.005 (peak area S14: isomer B1), 10.664±0.005 (peak area S15), 10.733±0.005 (peak area S16), 10.790±0.005 (peak area S17) and 10.858±0.005 (peak area S18). The molar percentage of isomer B1 in MACM is calculated based on the peak area ratio (R2) using the formula R2=S14 / (S14+S15+S16+S17+S18).

[0070] It should be noted that different chromatographic columns and test conditions result in different retention times, but this does not affect the peak order or proportion.

[0071] In addition, test errors caused by sample concentration and GCMS equipment status may lead to slight deviations in the specific peak times. For example, the peak times of each component in polyamide and the peak times of PACM and MACM monomers may be slightly different, which is normal.

[0072] The gas chromatogram of MACM30 is as follows: Figure 2 As shown (time unit is min); in the order of appearance, it includes the first main peak, the second main peak, the third main peak, the fourth main peak, and the fifth main peak; among them, the isomer corresponding to the first main peak, that is, the retention time of 10.587 min, is the isomer B1 described in this invention.

[0073] 3. R Take 5 mg of polyamide sample, add 20 mg of trifluoroacetic acid and 20 mg of hydrobromic acid, heat at 140℃ for 24 h, then take 10 μL of the extract and dissolve it in anhydrous ethanol. Analyze the sample using an Agilent 7890B gas chromatograph. Specific methods: Column type: HP5MS, 30 m × 0.25 mm × 0.25 µm, 7-inch column; programmed temperature ramp: column oven temperature: 80℃ for 1 min, ramped up to 260℃ at a rate of 15℃ / min, held for 5 min; injection port 280℃, auxiliary heater 280℃.

[0074] In the gas chromatogram, the shortest elution retention time is for PACM isomer A1, followed by PACM isomer A2, PACM isomer A3, and MACM isomer B1. By integrating the areas of the four peaks, and labeling the peak areas as S1 (PACM isomer A1), S2 (PACM isomer A2), S3 (PACM isomer A3), and S4 (MACM isomer B1), the R value can be obtained; that is, R = S1 / S4.

[0075] The gas chromatogram of the polyamide provided in Example 8 is as follows: Figure 1 As shown (time unit is min); according to the order of appearance, the first main peak, that is, the peak with a retention time of 9.905 min, has a peak area of ​​S1; the fourth main peak, that is, the peak with a retention time of 10.591 min, has a peak area of ​​S4, then R = S1 / S4.

[0076] 4. Tg Referring to GB / T 19466.1-2004, the specific test method is as follows: The glass transition temperature of the sample is tested using a Netzsch-TG 200 F3 DSC analyzer under a nitrogen atmosphere at a flow rate of 50 mL / min. During the test, the temperature is first increased to 250℃ at a rate of 20℃ / min and held at 250℃ for 2 min to remove the thermal history of the sample. Then, the temperature is cooled to 50℃ at a rate of 20℃ / min and held at 50℃ for 2 min. The temperature is then increased to 250℃ at a rate of 20℃ / min. The change of the baseline towards the endothermic direction is then marked with tangents to the inflection points of the curves on the extended lines of the two baselines before and after the step. The average value of the temperatures corresponding to the two intersection points is taken as the glass transition temperature (Tg).

[0077] 5. Light transmittance and haze Polyamide was injection molded to obtain a square plate with a thickness of 2 mm; the transmittance and haze were measured using a WGT-S transmittance and haze meter according to GB / T2410-2008 standard.

[0078] 6. Flexural modulus Referring to ISO 178:2019 standard, the flexural modulus of polyamide was measured using a universal testing machine with a standard injection molding specimen; the span was 64 mm, the specimen thickness was 4 mm, and the strain rate was 5 mm / min.

[0079] Examples 1-9, Comparative Examples 1-5 Examples 1-9 and Comparative Examples 1-5 each provide a polyamide, and the specific structural composition, R value, Tg and related properties of the polyamide are shown in Tables 2-3.

[0080] Unless otherwise specified, the preparation method of the polyamide of the present invention includes: adding reaction raw materials (diamine and diacid) to a pressure vessel equipped with a magnetic coupling stirrer, a condenser, a gas phase port, a feeding port, and a pressure explosion-proof port according to the formula; then adding benzoic acid, sodium hypophosphite (catalyst), antioxidant 1098, and deionized water; the amount of benzoic acid is 3% of the total molar content of diamine and diacid, the weight of sodium hypophosphite is 0.1% of the weight of other ingredients excluding deionized water, and the weight of deionized water is 30% of the total weight of ingredients; the mass of antioxidant 1098 is 0.2% of the weight of other ingredients excluding deionized water; evacuating and filling with high-purity nitrogen as a protective gas, raising the temperature to 190°C within 1 hour, stirring the reaction mixture at 190°C for 1 hour, and then raising the temperature of the reactants to 250°C with stirring; the reaction is kept constant at 250°C for 2.6 hours. The reaction was continued for 1 hour under constant pressure of MPa. The pressure was then released to atmospheric pressure by removing the water formed. The temperature was then raised to 270°C and reacted for 2 hours under vacuum conditions of 270°C and 50 Pa. After the vacuum was removed, nitrogen was introduced again to bring the pressure inside the reactor to a positive pressure of 0.5 MPa. Then the material was discharged, stretched, granulated and dried to obtain the polyamide.

[0081] Unless otherwise specified, all inventions are carried out at room temperature and pressure.

[0082] Comparative Example 6 This comparative example provides a polyamide. The preparation method of the polyamide differs from that of Example 1 in that high-purity nitrogen is introduced as a protective gas under vacuum, and the temperature is raised to 150°C within 1 hour. The reaction mixture is stirred at 150°C for 1 hour, and then the temperature of the reactants is raised to 200°C under stirring. The reaction is continued for 1 hour under constant temperature of 200°C and constant pressure of 2.6 MPa. The pressure is released to atmospheric pressure by removing the formed water, and then the temperature is raised to 270°C. The reaction is carried out for 2 hours under vacuum conditions of 270°C and 50 Pa. After vacuuming, nitrogen is introduced again to bring the pressure inside the reactor to a positive pressure of 0.5 MPa. Then the material is discharged, stretched, granulated, and dried to obtain the polyamide. Other raw materials and dosages are the same as in Example 1. The R value and performance results of the polyamide are shown in Table 3.

[0083] Table 2 Table 3 As shown in Tables 2 and 3, the polyamide provided by this invention uses a specific composition of diamine residues and diacid residues, and controls the R value to be ≥1.79, which is beneficial to improving the flexural modulus of the polyamide. At the same time, by further adjusting R within a specific range, the polyamide can also ensure good temperature resistance, processing performance and light transmittance, so that the polyamide meets the application requirements of thin-walled AR glasses frames. The glass transition temperature of the polyamide is 135~155℃, the flexural modulus is ≥1800MPa, the light transmittance is ≥84%, and the haze is ≤0.7%.

[0084] As can be seen from Examples 1 and 9, the same content of PACM and MACM, the same R value, the molar percentage of isomer A1 in PACM in the range of 25~43% and the molar percentage of isomer B1 in MACM in the range of 29~32% are more conducive to balancing temperature resistance and flexural modulus.

[0085] As can be seen from Example 1 and Comparative Examples 1 and 6, when the R value is not within a specific range (less than 1.79), the flexural modulus of the polyamide deteriorates significantly.

[0086] As can be seen from Example 2 and Comparative Examples 2, 3, and 4, the polyamide obtained by not using a combination of bis(4-aminocyclohexyl)methane residues and bis(3-methyl-4-aminocyclohexyl)methane residues has a lower flexural modulus, poorer light transmittance, and higher haze, making it difficult to apply to the field of thin-walled eyeglass frame materials.

[0087] As can be seen from Example 2 and Comparative Example 5, the polyamide obtained by not using 1,12-dodecyl dicarboxylic acid residues has a lower flexural modulus and worse temperature resistance.

[0088] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polyamide, characterized in that, The polyamide includes diamine residues and diacid residues; The diamine residues include bis(4-aminocyclohexyl)methane residues and bis(3-methyl-4-aminocyclohexyl)methane residues; The dicarboxylic acid residues include 1,12-dodecyl diacid residues; In the gas chromatogram of the polyamide, the peak area of ​​the first main peak is denoted as S1; the peak area of ​​the fourth main peak is denoted as S4; R = S1 / S4, R ≥ 1.79; The first main peak is the chromatographic peak of isomer A1 in bis(4-aminocyclohexyl)methane residues; The fourth main peak is the chromatographic peak of isomer B1 in bis(3-methyl-4-aminocyclohexyl)methane residues.

2. The polyamide according to claim 1, characterized in that, The value of R is ≥3.5, and more preferably R is 4.4~8.

3. The polyamide according to claim 1 or 2, characterized in that, The bis(4-aminocyclohexyl)methane residues are derived from bis(4-aminocyclohexyl)methane, and the first main peak in the gas chromatogram of the bis(4-aminocyclohexyl)methane is the chromatographic peak of the isomer A1. The molar percentage of isomer A1 in the bis(4-aminocyclohexyl)methane is 19-51%, more preferably 25-43%; Preferably, the bis(3-methyl-4-aminocyclohexyl)methane residues are derived from bis(3-methyl-4-aminocyclohexyl)methane, and the first main peak in the gas chromatogram of bis(3-methyl-4-aminocyclohexyl)methane is the chromatographic peak of isomer B1; The molar percentage of isomer B1 in the bis(3-methyl-4-aminocyclohexyl)methane is 28-40%, more preferably 29-32%.

4. The polyamide according to any one of claims 1 to 3, characterized in that, Based on a total molar amount of 100 mol% of diamine residues, the molar percentage of bis(4-aminocyclohexyl)methane residues is 73.5-86.5 mol%, more preferably 76-85.5 mol%.

5. The polyamide according to any one of claims 1 to 4, characterized in that, The glass transition temperature of the polyamide is 135~155℃.

6. The polyamide according to any one of claims 1 to 5, characterized in that, The flexural modulus of the polyamide is ≥1800MPa, more preferably 2000~2162MPa; Preferably, the polyamide has a light transmittance of ≥84% and a haze of ≤0.7%.

7. A method for preparing polyamide according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: A dicarboxylic acid and a diamine are mixed and subjected to a gradient heating reaction to obtain the polyamide.

8. The preparation method according to claim 7, characterized in that, The mixed materials also include at least one of solvent, capping agent, catalyst, and antioxidant.

9. A polyamide resin composition, characterized in that, The polyamide resin composition comprises the polyamide according to any one of claims 1 to 6.

10. A high-modulus transparent product, characterized in that, The high-modulus transparent article comprises the polyamide as described in any one of claims 1 to 6 or the polyamide resin composition as described in claim 9.

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