Semi-aromatic transparent polyamide material and preparation method thereof

Abstract

The invention discloses a semi-aromatic transparent polyamide material and a preparation method thereof, and belongs to the technical field of high polymer materials. The material is a random copolymer prepared by condensation polymerization of aromatic dibasic acid, aliphatic diamine and a multifunctional comonomer, the multifunctional comonomer has a general formula of H2N-R3-(R2-O) n-R1-(O-R2) n-R3-NH2, under the protection of inert gas, the raw materials are mixed with water, a catalyst and an end-capping reagent to form a slurry, the slurry is heated, pressurized and pre-polymerized, the pre-polymerized slurry is cooled to room temperature, and a finished product is obtained. And carrying out decompression dehydration or solid phase polycondensation to obtain a final product. The semi-aromatic transparent polyamide material synchronously realizes high transparency, high heat resistance and excellent mechanical properties, solves the problem of performance balance in the prior art, and is suitable for the high-end fields of optical lenses, electronic device shells, automobile lampshades and the like.

Description

Technical Field

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

[0002] Semi-aromatic polyamides are a class of engineering plastics whose molecular chains contain both aromatic rings and aliphatic segments. They combine the good processability of aliphatic polyamides with the heat resistance and high strength of fully aromatic polyamides. By suppressing their crystallinity through molecular structure design, transparent polyamide materials can be produced, which are widely used in optical instruments, electronic devices, automotive parts, and other fields.

[0003] In existing technologies, the main methods for preparing transparent polyamides include copolymerization modification and blending modification. Chinese patent CN101372531B discloses a transparent copolyamide prepared from dimer acid, aromatic diacid, and aliphatic linear diamine as raw materials, with a light transmittance exceeding 90%. Chinese patents CN103435796B and CN103483581B respectively disclose random copolymer transparent polyamide materials composed of semi-aromatic amide salts and aliphatic amide salts. Furthermore, research papers have also reported the synthesis of semi-aromatic copolyamides with high transparency, excellent heat resistance, and melt flowability through the synergistic effect of three monomers: isophthalic acid (IPA), 4,4'-methylenebis(cyclohexylamine) (PACM), and 1,6-hexanediamine (HMD).

[0004] However, existing technologies still have the following drawbacks: 1. Performance balancing challenge: There is a "seesaw effect" between transparency and mechanical properties and heat resistance, making it difficult to simultaneously achieve high light transmittance (>90%), high heat resistance (HDT>150℃), and high mechanical strength (tensile strength>80MPa); 2. Insufficient processing performance: The melting points of many high-performance semi-aromatic polyamides are close to or even exceed their decomposition temperatures, resulting in a narrow processing window and high equipment requirements; 3. High cost: To achieve high performance and high transparency, expensive special monomers (such as cyclic aliphatic diamines) are usually required, increasing production costs; 4. Limitations of modification methods: Blending methods are prone to compatibility problems, and nanocomposite modification presents dispersibility challenges, affecting transparency and mechanical properties.

[0005] Therefore, it is of great significance to develop a semi-aromatic transparent polyamide material that can simultaneously achieve high transparency, excellent mechanical properties, good heat resistance, and processability. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a semi-aromatic transparent polyamide material and its preparation method. This material effectively solves the problem of balancing transparency, mechanical properties, heat resistance, and processability by introducing novel multifunctional comonomers.

[0007] The technical solution of the present invention is as follows:

[0008] A semi-aromatic transparent polyamide material is a random copolymer obtained by polycondensation reaction of raw materials including the following monomers:

[0009] Aromatic dicarboxylic acids or their derivatives;

[0010] Aliphatic diamines;

[0011] The multifunctional comonomer has the general molecular formula: H2N-R3-(R2-O). n -R1-(O-R2) n -R3-NH2

[0012] Wherein, R1 is at least one bulky asymmetric rigid group selected from biphenyl, spiro[4.5]decyl, and adamantyl;

[0013] R2 is ethylidene, propyleneide, or butylidene;

[0014] R3 is a C1-C6 alkylene group;

[0015] n is an integer from 1 to 3.

[0016] The preparation method of the multifunctional comonomer includes the following steps:

[0017] (1) Etherification reaction: The starting material containing a large volume of asymmetric rigid groups (such as biphenyl, spiro[4.5]decanediol or adamantanediol) is dissolved in an organic solvent (such as DMF) and reacted with a haloalkane etherifying agent (such as 2-bromoethanol, 1-bromopropane, etc.) at 95-105℃ for 11-13h in the presence of a base (such as K2CO3) to generate an intermediate HO-R2-O-R1-O-R2-OH containing rigid groups and flexible ether chain segments;

[0018] (2) Amination reaction: The above intermediate is reacted with an aminoalkylating agent (such as acrylonitrile or hexenonitrile), and then the cyano group is reduced to an amino group by catalytic hydrogenation (such as Pd / C catalytic hydrogenation), or other amination methods are used. Finally, the target multifunctional comonomer H2N-R3-(R2-O) is obtained by purification. n -R1-(O-R2) n -R3-NH2.

[0019] The synthetic route is simple and the raw materials are readily available. By flexibly selecting the starting material R1 and the etherifying agent, the rigid and flexible chain lengths (n value) of the monomer and the terminal amino spacer group (R3) can be controlled, thereby realizing the molecular design of the final polyamide material properties.

[0020] The preparation method of the semi-aromatic transparent polyamide material includes the following steps:

[0021] (1) Under the protection of inert gas, aromatic dicarboxylic acid or its derivatives, aliphatic diamine, multifunctional comonomer, end-capping agent, catalyst and deionized water are added to a high-pressure reactor and stirred to form a reaction slurry;

[0022] (2) Gradually raise the temperature of the reaction system to 200-280℃ and maintain the pressure at 1.5-4.0MPa for 2-6 hours to carry out the prepolymerization reaction and obtain the prepolymer;

[0023] (3) After dehydration or solid-phase polycondensation of the prepolymer, it is melt-extruded and granulated to obtain the semi-aromatic transparent polyamide material.

[0024] This invention ensures transparency by inhibiting crystallization through rigid groups, improves processing fluidity through ether chain segments, and maintains heat resistance and strength through a rigid structure, which is significantly superior to traditional copolymer or blend modified materials.

[0025] The amount of the multifunctional comonomer added is 5% to 40% of the total molar amount of the aliphatic diamine.

[0026] The amount of the aromatic dicarboxylic acid or its derivative added is 95% to 105% of the total molar amount of the aliphatic diamine.

[0027] The capping agent is benzoic acid or acetic acid, and its addition amount is 0.5% to 2.5% of the total molar amount of aliphatic diamine.

[0028] The catalyst is sodium hypophosphite or hypophosphite, and its addition amount is 0.01% to 0.5% of the total weight of the raw materials.

[0029] Preferably, the aromatic dicarboxylic acid is terephthalic acid, isophthalic acid, or a mixture thereof; and the aliphatic diamine is at least one of hexamethylenediamine, decanediamine, and dodecanodiamine.

[0030] The characteristic performance indicators of the semi-aromatic transparent polyamide material prepared by this invention are: light transmittance (according to ASTM D1003 standard) greater than 91%, haze less than 2.0%, heat distortion temperature (1.8MPa) greater than 175℃, and tensile strength greater than 85MPa.

[0031] Preferably, the solid content of the reaction slurry in step (1) is 50%-80%.

[0032] Preferably, the temperature of the prepolymerization reaction in step (2) is 230-260℃, the pressure is 2.0-3.0MPa, and the reaction time is 3-5 hours.

[0033] Preferably, the solid-phase polycondensation conditions in step (3) are: reaction at 180-220°C for 4-12 hours under an inert gas atmosphere or vacuum.

[0034] The semi-aromatic transparent polyamide material or its composition of the present invention can be used to prepare optical lenses, electronic device housings, automotive lamp covers or medical device components.

[0035] Compared with the prior art, the present invention has the following superior effects:

[0036] 1. This invention cleverly resolves the contradiction between transparency, mechanical properties, and heat resistance by introducing a novel "rigid-flexible" multifunctional copolymer monomer. The large-volume asymmetric rigid group (R1) effectively inhibits crystallization and ensures high transparency; the flexible ether chain segment (-(O-R2)n-) improves processing fluidity and widens the processing window; the rigid group simultaneously provides high heat resistance and mechanical strength.

[0037] 2. The material of this invention simultaneously achieves high light transmittance (>91%), low haze (<2.0%), high heat resistance (HDT>175℃) and high mechanical strength (tensile strength>85MPa), and its performance indicators exceed the level reported in the prior art.

[0038] 3. The introduction of flexible ether bonds significantly improves the melt flowability of the material, reduces the processing temperature, and widens the processing window, making the material easier to process and shape using conventional methods such as injection molding and extrusion.

[0039] 4. This invention achieves performance optimization through molecular design, reduces dependence on expensive special monomers, lowers raw material costs, simplifies the preparation process, and is conducive to industrial production.

[0040] 5. The semi-aromatic transparent polyamide prepared by this invention has excellent comprehensive properties and has broad application prospects in high-end fields such as optical lenses, electronic device housings, automotive lamp covers, and medical device components. Detailed Implementation

[0041] The present invention will be specifically described below through embodiments, but the present invention is not limited to these embodiments.

[0042] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0043] Example 1

[0044] (1) Preparation of adamantyl etheramine monomer:

[0045] Adamantanediol (152.2 g, 1.0 mol) was dissolved in DMF, and K2CO3 (276 g, 2.0 mol) and 2-bromoethanol (250 g, 2.0 mol) were added. The mixture was reacted at 100 °C for 12 hours. The salt was removed by filtration, and the product was distilled under reduced pressure to give a white solid HO-CH2CH2-O-adamantyl-O-CH2CH2-OH (yield 92%).

[0046] The above intermediate (128 g, 0.5 mol), acrylonitrile (53 g, 1.0 mol), and sodium methoxide (27 g) were refluxed in ethanol for 6 hours. After cooling, the mixture was filtered, and the filtrate was hydrogenated by Pd / C catalysis (50 °C, 2 MPa H2) to give H2N-CH2-(CH2CH2-O)2-adamantyl-(O-CH2CH2)2-CH2-NH2 (GC purity >98%, yield 87%).

[0047] (2) Preparation of semi-aromatic transparent polyamide

[0048] Under nitrogen protection, terephthalic acid (166.1 g, 1.0 mol), hexamethylenediamine (104.6 g, 0.9 mol), the multifunctional comonomer H2N-CH2-(CH2CH2-O)2-adamantyl-(O-CH2CH2)2-CH2-NH2 (37.0 g, 0.1 mol), benzoic acid (2.4 g, 0.02 mol), sodium hypophosphite (0.3 g), and deionized water (300 g) were added to a high-pressure reactor. The mixture was stirred to form a homogeneous slurry with a solid content of approximately 60%.

[0049] The reaction system was heated to 250°C at a rate of 2°C / min, and the pressure was maintained at 2.5 MPa for 4 hours of prepolymerization. The pressure was then slowly released to atmospheric pressure, and the reaction continued for 1 hour. The resulting prepolymer was subjected to solid-state polycondensation at 200°C for 8 hours under nitrogen protection. After granulation by a twin-screw extruder and cutting, a semi-aromatic transparent polyamide material was obtained.

[0050] The material performance test results are as follows: light transmittance 92.5%, haze 1.8%, heat distortion temperature (1.8MPa) 182℃, and tensile strength 88MPa.

[0051] Example 2

[0052] (1) Preparation of biphenyl etheramine comonomer

[0053] Following the method of Example 1, except that adamantane diol was replaced with biphenyl glycol (186 g, 1 mol), the resulting multifunctional comonomer was H2N-CH2-(CH2CH2-O)2-biphenyl-(O-CH2CH2)2-CH2-NH2.

[0054] (2) Preparation of semi-aromatic transparent polyamide

[0055] The method is the same as in Example 1, except that the multifunctional comonomer is replaced with H2N-CH2-(CH2CH2-O)2-biphenyl-(O-CH2CH2)2-CH2-NH2 (38.8 g, 0.1 mol), and the amount added is 10% of the total moles of the diamine.

[0056] The material performance test results are as follows: light transmittance 91.8%, haze 1.9%, heat distortion temperature (1.8MPa) 178℃, and tensile strength 86MPa.

[0057] Example 3

[0058] The method is the same as in Example 1, except that the hexamethylenediamine is adjusted to 80% of the total molar amount of the diamine (92.96 g, 0.8 mol), and the amount of multifunctional comonomer added is adjusted to 20% of the total molar amount of the diamine (74.0 g, 0.2 mol).

[0059] The material performance test results are as follows: light transmittance 93.1%, haze 1.6%, heat distortion temperature (1.8MPa) 176℃, and tensile strength 87MPa.

[0060] Comparative Example 1

[0061] The method of Example 1 is followed, but without the addition of a multifunctional comonomer.

[0062] The resulting material is an opaque white granule with a light transmittance of only 65.3%, a haze as high as 32.5%, a heat distortion temperature (1.8 MPa) of 195°C, and a tensile strength of 92 MPa. This indicates that the multifunctional comonomer of this invention is lacking, making it impossible to achieve the required transparency.

[0063] Comparative Example 2

[0064] The method of Example 1 is followed, but the multifunctional comonomer is replaced with an equimolar amount of ordinary cyclohexanediamine.

[0065] The resulting material has a light transmittance of 85.6%, a haze of 5.2%, a heat distortion temperature (1.8 MPa) of 162°C, and a tensile strength of 78 MPa. These properties are all lower than those of the embodiments of this invention, indicating that the specific multifunctional comonomer structure of this invention is crucial for achieving high performance.

[0066] The above embodiments illustrate that by introducing a multifunctional comonomer with a specific structure, the present invention has successfully prepared a semi-aromatic transparent polyamide material with excellent comprehensive performance, effectively solving the performance balance problem in the prior art.

[0067] The above are only some embodiments of the present invention. The present invention is not limited to the above embodiments. Improvements and modifications that do not depart from the essential scope of the present invention are all within the protection scope of the present invention.

Claims

1. A semi-aromatic transparent polyamide material, characterized in that, It is a random copolymer obtained by polycondensation reaction of raw materials including the following monomers: Aromatic dicarboxylic acids or their derivatives; Aliphatic diamines; The multifunctional comonomer has the general molecular formula: H2N-R3-(R2-O). n -R1-(O-R2) n -R3-NH2 Wherein, R1 is at least one bulky asymmetric rigid group selected from biphenyl, spiro[4.5]decyl, and adamantyl; R2 is ethylidene, propyleneide, or butylidene; R3 is a C1-C6 alkylene group; n is an integer from 1 to 3.

2. The semi-aromatic transparent polyamide material according to claim 1, characterized in that, The preparation method of the multifunctional comonomer includes the following steps: (1) Etherification reaction: The starting material containing the R1 group is dissolved in an organic solvent and reacted with a haloalkane etherifying agent in the presence of a base at 95-105℃ for 11-13h to generate the intermediate HO-R2-O-R1-O-R2-OH. (2) Amination reaction: The above intermediate was reacted with an aminoalkylating agent, followed by amination and purification to obtain the multifunctional comonomer H2N-R3-(R2-O). n -R1-(O-R2) n -R3-NH2.

3. The semi-aromatic transparent polyamide material according to claim 2, characterized in that, The haloalkane etherifying agent is 2-bromoethanol or 1-bromopropane, and the aminoalkylating agent is acrylonitrile or hexenonitrile.

4. The method for preparing a semi-aromatic transparent polyamide material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Under the protection of inert gas, aromatic dicarboxylic acid or its derivatives, aliphatic diamine, multifunctional comonomer, end-capping agent, catalyst and water are added to a high-pressure reactor and stirred to form a reaction slurry; (2) Gradually raise the temperature of the reaction system to 200-280℃ and maintain the pressure at 1.5-4.0MPa for 2-6 hours to carry out the prepolymerization reaction and obtain the prepolymer; (3) After dehydration or solid-phase polycondensation of the prepolymer, it is melt-extruded and granulated to obtain the semi-aromatic transparent polyamide material.

5. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The aromatic dicarboxylic acid is terephthalic acid, isophthalic acid, or a mixture thereof; the aliphatic diamine is at least one of hexamethylenediamine, decanediamine, and dodecanodiamine; the end-capping agent is benzoic acid or acetic acid; and the catalyst is sodium hypophosphite or hypophosphite.

6. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The amount of the multifunctional comonomer added is 5% to 40% of the total molar amount of the aliphatic diamine; the amount of the aromatic dicarboxylic acid or its derivative added is 95% to 105% of the total molar amount of the aliphatic diamine; the amount of the end-capping agent added is 0.5% to 2.5% of the total molar amount of the aliphatic diamine; and the amount of the catalyst added is 0.01% to 0.5% of the total weight of the raw materials.

7. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The solid content of the reaction slurry in step (1) is 50%-80%.

8. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The temperature of the prepolymerization reaction in step (2) is 230-260℃, the pressure is 2.0-3.0MPa, and the reaction time is 3-5 hours.

9. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The solid-phase polycondensation conditions described in step (3) are: reaction at 180-220℃ for 4-12 hours under an inert gas atmosphere or vacuum.

10. The method for preparing a semi-aromatic transparent polyamide material according to claim 4, characterized in that, The prepared semi-aromatic transparent polyamide material has a light transmittance greater than 91%, a haze less than 2.0%, a heat distortion temperature of 175℃, and a tensile strength greater than 85MPa.