A diacid, high-barrier nylon resin, and a preparation method and application thereof

Abstract

The application discloses a diacid, a high-barrier nylon resin and a preparation method and application of the diacid, and has the molecular structural formula of The preparation method of the diacid comprises the following steps: adding halogen-substituted carbazole, an organic boron compound, a catalyst and a promoting metal transfer auxiliary into a strong polar solvent, refluxing, filtering, and drying to obtain the diacid. The high-barrier nylon resin has the molecular structural formula of wherein a=6, 9, 10, 12 or 14, b=4, 8, 10 or 12, and the molar ratio of m to n is 10-50:70-190. The application further discloses a preparation method and application of the high-barrier nylon resin. The diacid has a large planar structure, high reaction activity and excellent thermal stability. The high-barrier nylon resin product is diversified, and has excellent mechanical properties, heat resistance and gas barrier property. The method has simple production process and is suitable for industrialized continuous production.

Description

Technical Field

[0001] This invention relates to a diacid, a nylon resin, its preparation method and application, specifically to a diacid, a high-barrier nylon resin, its preparation method and application. Background Technology

[0002] Polymer barrier materials are playing an increasingly important role in the packaging industry due to their advantages such as light weight, fragility, corrosion resistance, and ease of processing. Therefore, with the widespread application of barrier packaging materials, the demand for such materials is growing, and research on various polymer barrier materials is attracting increasing attention. In recent years, improving the barrier properties of polymer materials without sacrificing their thermal and mechanical properties has become a hot research topic.

[0003] Polyamide, commonly known as nylon, is a general term for resins containing repeating amide groups in their molecular chains. It is mainly formed by the condensation polymerization of lactams, amino acids, or nylon salts (obtained through a salt-forming reaction of diacids and diamines). Nylon is a class of thermoplastic resins with excellent comprehensive properties. Among the five major general-purpose engineering plastics, it has the largest production volume, the most varieties, and the widest range of applications. After more than 70 years of development, the application of nylon has expanded from spinning fibers to film packaging, engineering plastics, and other fields. Due to the strong polar amide groups on its main chain, nylon easily forms hydrogen bonds, increasing intermolecular forces and exhibiting good gas barrier properties, chemical stability, and solvent resistance. As a common barrier material, nylon, with its performance advantages, can be widely used in automotive plastic fuel tanks and barrier packaging materials. However, the strong hydrophilicity of the amide groups results in poor moisture barrier properties for nylon; changes in environmental humidity significantly affect the barrier properties and dimensional stability of nylon products.

[0004] CN103160119A discloses a castable nylon nanobarrier material, which is made of the following components in parts by weight: 770-947 parts caprolactam, 1-10 parts catalyst, 1-10 parts activator, 50-150 parts nylon 66, 1-100 parts inorganic nano-oxides, and 0-10 parts other additives. This nylon nanobarrier material possesses high barrier properties, high strength, and high toughness, and has broad application prospects in automotive fuel tanks, high-barrier plastic bottles, battery separators, oil pipelines, and packaging materials. However, because the inorganic nano-oxides added to this nylon nanobarrier material are primarily spherical, their barrier effect against gas or water molecules is inferior to that of layered or sheet-like inorganic nanofillers; furthermore, without surface modification treatment, their dispersion in the caprolactam matrix is ​​poor, affecting the barrier and mechanical properties of the final product.

[0005] CN113881221A discloses a high-barrier nylon blend material comprising the following components in parts by weight: 60-100 parts nylon resin, 10-30 parts ethylene-vinyl alcohol copolymer, 10-20 parts montmorillonite, 1-5 parts antibacterial agent, and 1-3 parts dispersant. This high-barrier nylon blend material exhibits high barrier and antibacterial properties. However, the nylon resin used is long-chain nylon 11, which has a low upper limit temperature for use and is not suitable for special applications with stringent temperature requirements.

[0006] CN106009640A discloses a high-barrier graphene oxide / nylon nanocomposite material and its preparation method. The barrier properties and mechanical strength of the composite material are improved to a certain extent, but its grafting rate is low, which means that the barrier performance of the material can only be slightly improved, and only black nylon products can be produced.

[0007] In summary, the reported methods for preparing barrier nylon mainly focus on composite modification, with fewer cases of copolymer modification. The resulting barrier nylons tend to have problems such as poor mechanical strength, low heat resistance, and limited product color.

[0008] Therefore, there is an urgent need to find a diacid with a large planar structure, high reactivity, and excellent thermal stability, and to use it to polymerize high-barrier nylon resins with diversified products, excellent mechanical properties, heat resistance, and gas barrier properties, as well as applications, and a simple production process suitable for continuous industrial production of diacid and high-barrier nylon resins. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a diacid with a large planar structure, high reactivity and excellent thermal stability.

[0010] The technical problem to be further solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing diacid with a simple production process that is suitable for continuous industrial production.

[0011] The technical problem to be further solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a high-barrier nylon resin with diversified products, excellent mechanical properties, heat resistance, and gas barrier properties, and its applications.

[0012] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing high-barrier nylon resin with a simple production process that is suitable for continuous industrial production.

[0013] The technical solution adopted by this invention to solve its technical problem is as follows: a diacid, the molecular structural formula of which is: The diacid molecular structure designed in this invention contains two terminal carboxyl groups and has almost no steric hindrance, thus exhibiting high reactivity; at the same time, it contains a benzene ring and a carbazole structure, which, compared to a single aliphatic carbon chain structure, will exhibit excellent thermal stability.

[0014] The technical solution adopted by this invention to further solve its technical problem is as follows: A method for preparing diacid, comprising adding halogen-substituted carbazole, an organoboron compound, a catalyst, and a metal transfer promoter to a strongly polar solvent, refluxing the mixture, filtering, and drying to obtain diacid. During the refluxing reaction, because the reaction temperature is higher than the boiling point of the strongly polar solvent, the strongly polar solvent boils, and under the condensation effect of the condenser, reflux is formed, which accelerates the reaction and prevents the volatilization of the strongly polar solvent.

[0015] The inventive concept of the method for preparing the diacid of the present invention is as follows: The method of the present invention uses halogen-substituted carbazole and organoboron compounds as raw materials to prepare a novel diacid through the Suzuki-Miyaura reaction. It has excellent reactivity and thermal stability and is suitable for the high temperature and high pressure melt polycondensation reaction process of nylon.

[0016] Preferably, the molar ratio of the halogen-substituted carbazole, organoboron compound, catalyst and metal transfer promoter is 1:2.0-2.2:0.05-0.10:0.8-1.0 (more preferably 1:2.0-2.2:0.05-0.08:0.9-1.0).

[0017] Preferably, the amount of the strongly polar solvent is equivalent to 1.5 to 2.5 times (more preferably 1.8 to 2.4 times) the total mass of the halogen-substituted carbazole, organoboron compound, catalyst, and metal transfer promoter.

[0018] Preferably, the reflux reaction temperature is 1.05 to 1.10 times the boiling point temperature of the strongly polar solvent, and the time is 18 to 30 hours.

[0019] Preferably, the halogenated carbazole includes one or more of 3,6-dichlorocarbazole, 3,6-dibromocarbazole, or 3,6-diiodocarbazole.

[0020] Preferably, the organoboron compound includes 4-carboxyphenylboronic acid, etc.

[0021] Preferably, the catalyst comprises one or more of tetra(triphenylphosphine)palladium, tris(dibenzylideneacetone)palladium, or di(triphenylphosphine)palladium dichloride.

[0022] Preferably, the metal transfer promoter includes one or more of the following: K3PO4, K2CO3, Na2CO3, KF, Ba(OH)2, potassium tert-butoxide, sodium tert-butoxide, or triethylamine.

[0023] Preferably, the highly polar solvent includes one or more of dichloromethane, trichloromethane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

[0024] The technical solution adopted by the present invention to further solve its technical problem is as follows: a high-barrier nylon resin, comprising the aforementioned diacid structure; its molecular structural formula is: Wherein, a = 6, 9, 10, 12 or 14 (more preferably a = 6, 9, 10 or 12), b = 4, 8, 10 or 12 (more preferably b = 4, 8 or 10); the molar ratio of m to n is 10-50:70-190 (more preferably 13-46:86-180). The molecular structure of the high-barrier nylon resin of the present invention contains carbazole, benzene rings and other structures, which can exhibit excellent heat resistance and barrier properties; diacids and diamines with different carbon chain lengths can be used to adjust the mechanical and processing properties of the high-barrier nylon resin. The limitation of a and b is mainly based on whether the corresponding diamine or diacid is readily available or can be produced in large quantities industrially, thus affecting the continuous industrial production of the high-barrier nylon resin of the present invention.

[0025] The technical solution adopted by the present invention to further solve its technical problem is as follows: A method for preparing high-barrier nylon resin, comprising the following steps:

[0026] (1) Add the diacid and aliphatic diamine to water and stir to form a salt to obtain component Sx salt solution; add the aliphatic diacid and m-phenylenediamine to water and stir to form a salt to obtain nylon MXD-y salt solution;

[0027] (2) The Sx salt solution and nylon MXD-y salt solution obtained in step (1) are added to the reactor along with the catalyst. The air in the reactor is replaced with inert gas and then filled with inert gas. Melt polycondensation is carried out, and then inert gas is filled again. The material is discharged to obtain high-barrier nylon resin.

[0028] The inventive concept of the preparation method of the high-barrier nylon resin of the present invention is as follows: the novel diacid molecular structure contains a rigid, large planar carbazole unit, which can reduce the internal rotational freedom of the nylon molecular chain, thereby increasing the packing density of the nylon molecular chain and significantly reducing the free volume inside the polymer. Based on this novel diacid, it is salted with an aliphatic diamine to obtain component Sx solution, and then copolymerized with nylon MXD-y salt solution to obtain a high-barrier nylon resin with better mechanical properties, heat resistance and barrier performance than the barrier nylon resin material obtained by homopolymerization of pure nylon MXD-y salt solution currently on the market.

[0029] Preferably, in step (1), the molar ratio of the diacid to the aliphatic diamine in the Sx salt solution is 0.96–1.00:1. Nylon resin meeting the desired viscosity requirements can be prepared at this ratio.

[0030] Preferably, in step (1), the amount of water used in the component Sx salt solution is 30-40% of the total mass of the diacid and the aliphatic diamine. Water acts as a reaction medium, and at this amount, a clear and transparent component Sx salt solution can be prepared.

[0031] Preferably, in step (1), the aliphatic diamine includes one or more of hexamethylenediamine, nonanediamine, decanediamine, 1,12-diaminododecane or 1,14-diaminotetradecane.

[0032] Preferably, in step (1), the molar ratio of the aliphatic dicarboxylic acid to m-phenylenediamine in the nylon MXD-y salt solution is 0.96 to 1.00:1. Nylon resin meeting the expected viscosity requirements can be prepared at this ratio.

[0033] Preferably, in step (1), the amount of water used in the nylon MXD-y salt solution is 30-40% of the total mass of the aliphatic dicarboxylic acid and m-phenylenediamine. Water acts as a reaction medium, and at the specified amount, a clear and transparent nylon MXD-y salt solution can be prepared.

[0034] Preferably, in step (1), the aliphatic dicarboxylic acid includes one or more of adipic acid, sebacic acid, dodecanoic acid, or tetradecanoic acid.

[0035] Preferably, in step (2), the mass ratio of the component Sx salt solution to the nylon MXD-y salt solution is 1:1 to 6 (more preferably 1:1 to 5).

[0036] Preferably, in step (2), the amount of catalyst used is 0.1 to 0.5% (more preferably 0.1 to 0.3%) of the total mass of component Sx salt solution and component Sx salt solution. At this amount, the catalyst can catalyze the polycondensation reaction to proceed in the forward direction, thereby obtaining a high-barrier nylon resin with the desired viscosity.

[0037] Preferably, in step (2), the catalyst includes one or more of sodium hypophosphite, potassium hypophosphite, or magnesium hypophosphite.

[0038] Preferably, in step (2), the specific process of melt polycondensation is as follows: first, a heating and pressure holding reaction is carried out, then gas is slowly released and a second heating and pressure holding reaction is carried out, the gas is released to normal pressure, the water in the system is discharged, and then a vacuum is gradually drawn to carry out a decompression reaction.

[0039] Preferably, the single-stage heating and pressure-holding reaction refers to heating to 210–225°C and maintaining the pressure inside the reactor at 2.0–2.5 MPa for 1.5–2.0 h (more preferably 1.7–2.0 h). The purpose of the single-stage heating and pressure-holding reaction is prepolymerization to obtain a low molecular weight, high-barrier nylon resin prepolymer.

[0040] Preferably, the slow venting and secondary heating and pressure holding reaction refers to: continuing to heat to 280-300℃ (more preferably 285-300℃), slowly venting during the heating process to maintain the pressure inside the reactor at 1.8-2.0 MPa, and reacting for 1.5-2.0 hours. The purpose of the secondary heating and pressure holding reaction is to remove moisture from the system and slowly increase the molecular weight of the high-barrier nylon resin prepolymer.

[0041] Preferably, the stepwise vacuuming for the decompression reaction refers to: first, evacuating to -0.01 to -0.03 MPa and holding the pressure for 15 to 25 minutes; then evacuating to -0.03 to -0.05 MPa and holding the pressure for 15 to 25 minutes; finally, evacuating to -0.05 to -0.07 MPa and holding the pressure for 12 to 30 minutes. The vacuum level of each subsequent evacuation is greater than the previous one. Before stepwise vacuuming, releasing gas to atmospheric pressure can further remove moisture from the system. The purpose of stepwise vacuuming is to further remove water generated during the post-condensation reaction, i.e., the decompression reaction, promoting the reaction in the forward direction and further increasing the molecular weight. The initial vacuum level is relatively low to avoid the reaction becoming too vigorous, which could cause the extracted moisture and oligomers to clog the vacuum pipes. The vacuum level is gradually increased subsequently to remove as much moisture as possible, obtaining nylon resin with the desired molecular weight.

[0042] More preferably, the stepwise vacuuming for decompression reaction refers to: first, vacuuming to -0.01 to -0.02 MPa, then holding the pressure for 20 to 25 minutes; then, vacuuming to -0.03 to -0.04 MPa, then holding the pressure for 20 to 25 minutes; and finally, vacuuming to -0.05 to -0.06 MPa, then holding the pressure for 12 to 24 minutes.

[0043] Preferably, before the melt polycondensation, the air inside the reactor is replaced with inert gas 3 to 4 times and then filled with inert gas to 0.1 to 0.2 MPa.

[0044] Preferably, after the melt polycondensation, an inert gas is introduced to a pressure of 0.2–0.3 MPa.

[0045] Preferably, the inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium. The inert gas used in this invention is a high-purity gas with a purity ≥ 99.999%.

[0046] The technical solution adopted by the present invention to further solve its technical problem is as follows: an application of high-barrier nylon resin, wherein the high-barrier nylon resin is used in the technical field of barrier packaging materials, etc.

[0047] The beneficial effects of this invention are as follows:

[0048] (1) The diacid of the present invention has a large planar structure, high reactivity and excellent thermal stability, which is suitable for the high-temperature melt polycondensation reaction of nylon;

[0049] (2) The high-barrier nylon resin of the present invention has a relative viscosity as high as 2.60, a tensile strength as high as 119 MPa, a flexural strength as high as 196 MPa, and an impact strength as high as 19 kJ / m. 2 It has a high melting point of 277.4℃, an initial decomposition temperature of 410.2℃, and an oxygen permeability as low as 1.2mL / (m³). 2 With a water absorption rate as low as 0.13%, it is suitable for special applications with stringent requirements for film barrier performance and operating temperature.

[0050] (3) The high-barrier nylon resin of the present invention has diversified products and can flexibly adjust the copolymerization ratio of component Sx salt solution and nylon MXD-y salt to customize the production of nylon resins with different heat resistance and barrier grades to meet the performance requirements of specific application sites.

[0051] (4) The production process of the method of the present invention is simple and suitable for industrial continuous production. Attached Figure Description

[0052] Figure 1 This is the time-of-flight mass spectrum of the diacid obtained in Example 1 of the method of the present invention;

[0053] Figure 2 This is the infrared spectrum of the high-barrier nylon resin obtained in Example 1 of the method of the present invention. Detailed Implementation

[0054] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0055] The inert gases used in the embodiments and comparative examples of this invention are high-purity gases with a purity of ≥99.999%; the raw materials or chemical reagents used in the embodiments of this invention, unless otherwise specified, are obtained through conventional commercial channels.

[0056] Example 1 of a diacid

[0057] The molecular structural formula of the diacid is: .

[0058] like Figure 1 As shown, a distinct characteristic peak of 407.224 m / z exists in the time-of-flight mass spectrum, corresponding to [M（二酸） +H （氢） ] + The measured molecular weight was consistent with the theoretical value of 407.12 g / mol, indicating that the diacid with the molecular structure described above was successfully synthesized in Example 1 of the present invention.

[0059] Example 2 of a diacid

[0060] The molecular structural formula of the diacid is: .

[0061] Upon examination, a distinct characteristic peak of 407.453 m / z was observed in the time-of-flight mass spectrum, corresponding to [M]. （二酸） +H （氢） ] + The measured molecular weight was consistent with the theoretical value of 407.12 g / mol, indicating that the diacid with the molecular structure described above was successfully synthesized in Example 2 of the present invention.

[0062] Example 3 of a diacid

[0063] The molecular structural formula of the diacid is: .

[0064] Upon examination, a distinct characteristic peak of 407.316 m / z was observed in the time-of-flight mass spectrum, corresponding to [M （二酸） +H （氢） ] + The measured molecular weight was consistent with the theoretical value of 407.12 g / mol, indicating that the diacid with the molecular structure described above was successfully synthesized in Example 3 of the present invention.

[0065] Example 1: A method for preparing a diacid

[0066] 325.0 g (1 mol) of 3,6-dibromocarbazole, 365.1 g (2.2 mol) of 4-carboxyphenylboronic acid, 57.8 g (0.05 mol) of Pd(PPh3)4 and 106.0 g (1 mol) of Na2CO3 were added to 1707.8 g (equivalent to twice the total mass of other raw materials) of tetrahydrofuran (boiling point 66℃). The mixture was refluxed at 70℃ for 24 h, filtered, and dried to obtain diacid (molecular weight 407.12 g / mol).

[0067] Example 2 of a method for preparing a dicarboxylic acid

[0068] 325.0 g (1 mol) of 3,6-dibromocarbazole, 348.5 g (2.1 mol) of 4-carboxyphenylboronic acid, 42.1 g (0.06 mol) of PdCl2(PPh3)2 and 101.2 g (1 mol) of triethylamine were added to 1715.3 g (equivalent to 2.1 times the total mass of other raw materials) of chloroform (boiling point 61.2℃). The mixture was refluxed at 65℃ for 24 h, filtered, and dried to obtain diacid (molecular weight 407.12 g / mol).

[0069] Example 3 of a method for preparing a dicarboxylic acid

[0070] 419.0 g (1 mol) of 3,6-diiodocarbazole, 332.0 g (2.0 mol) of 4-carboxyphenylboronic acid, 80.9 g (0.07 mol) of Pd(PPh3)4 and 212.3 g (1 mol) of K3PO4 were added to 2297.2 g (equivalent to 2.2 times the total mass of other raw materials) of N,N-dimethylformamide (boiling point 153℃). The mixture was refluxed at 162℃ for 18 h, filtered, and dried to obtain diacid (molecular weight 407.12 g / mol).

[0071] Example 1 of a high-barrier nylon resin

[0072] The molecular structure of the high-barrier nylon resin is as follows: , where a=6, b=4, m=18~20, n=162~180.

[0073] like Figure 2 As shown, 3292.33cm -1 The absorption peak for the NH stretching vibration is at 2936.32 cm⁻¹. -1 and 2861.11cm -1 The absorption peak at 1627.86 cm⁻¹ corresponds to the stretching vibration of the methylene group (CH). -1 The characteristic absorption peak of the amide I band is at 1539.32 cm⁻¹. -1 The characteristic absorption peak of the amide II band is at 1482.33 cm⁻¹. -1 The characteristic absorption peak of the benzene ring is present at the specified location, and no characteristic absorption peak of nylon salt is found, indicating that the method of Example 1 of the present invention successfully synthesized the high-barrier nylon resin with the described molecular structure.

[0074] Example 2 of a high-barrier nylon resin

[0075] The molecular structure of the high-barrier nylon resin is as follows: , where a=9, b=4, m=17~19, n=153~171.

[0076] Example 3 of a high-barrier nylon resin

[0077] The molecular structure of the high-barrier nylon resin is as follows: , where a=10, b=4, m=14~16, n=126~144.

[0078] Example 4 of a high-barrier nylon resin

[0079] The molecular structure of the high-barrier nylon resin is as follows: , where a=12, b=4, m=13~16, n=117~144.

[0080] Example 5 of a high-barrier nylon resin

[0081] The molecular structure of the high-barrier nylon resin is as follows: , where a=6, b=8, m=30~33, n=120~132.

[0082] Example 6 of a high-barrier nylon resin

[0083] The molecular structure of the high-barrier nylon resin is as follows: , where a=6, b=10, m=37~39, n=111~117.

[0084] Example 7 of a high-barrier nylon resin

[0085] The molecular structure of the high-barrier nylon resin is as follows: , where a=6, b=4, m=34~36, n=153~162.

[0086] Example 8 of a high-barrier nylon resin

[0087] The molecular structure of the high-barrier nylon resin is as follows: , where a=6, b=4, m=44~46, n=86~90.

[0088] Upon testing, in the above-mentioned high-barrier nylon resin examples 2 to 8, there were obvious absorption peaks of NH stretching vibration, methylene CH stretching vibration, characteristic absorption peaks of amide I band, characteristic absorption peaks of amide II band, and characteristic absorption peaks of benzene ring, which were similar in position to the characteristic peaks of high-barrier nylon resin example 1. No characteristic absorption peaks of nylon salt were found, indicating that the method of the present invention in examples 2 to 8 successfully synthesized the high-barrier nylon resin with the above-mentioned molecular structure.

[0089] Example 1: A method for preparing a high-barrier nylon resin

[0090] (1) Add 399.0g (0.98mol) of the diacid obtained in Example 1 and 116.2g (1mol) of hexamethylenediamine to 154.6g of water (water / (diacid + aliphatic diamine) = 30%, the same below), stir to form a salt, and obtain 669.8g of component S-6 salt solution; add 1289.0g (8.82mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine to 754.4g of water (water / (aliphatic diamine + m-phenylenediamine) = 30%, the same below), stir to form a salt, and obtain 3269.1g of nylon MXD-6 salt solution;

[0091] (2) Add 669.8g of component S-6 salt solution and 3269.1g of nylon MXD-6 salt solution obtained in step (1) and 7.9g of sodium hypophosphite into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 210℃ and maintain the pressure inside the reactor at 2.0MPa for one heating and pressure holding reaction for 2.0h. Continue to heat up to 300℃, slowly releasing the gas during the heating process to maintain the pressure inside the reactor at 0.15MPa. After a second heating and pressure holding reaction at 1.8 MPa for 1.5 h, the pressure inside the reactor was released to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the reactor for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 12 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0092] Example 2: A method for preparing a high-barrier nylon resin

[0093] (1) Add 399.0g (0.98mol) of the diacid obtained in Example 1 and 158.3g (1mol) of nonadiamine to 195.1g (35%) of water and stir to form a salt, to obtain 752.4g of component S-9 salt solution; add 1302.2g (8.91mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine to 884.8g (35%) of water and stir to form a salt, to obtain 3412.7g of nylon MXD-6 salt solution;

[0094] (2) Add 752.4g of component S-9 salt solution and 3412.7g of nylon MXD-6 salt solution obtained in step (1) and 10.4g of sodium hypophosphite into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 213℃ and maintain the pressure in the reactor at 2.1MPa for a single heating and pressure holding reaction for 2.0h. Continue to heat up to 295℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. The pressure was 1.9 MPa, and after a second heating and pressure holding reaction for 1.5 h, the pressure inside the reactor was released to bring it down to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 12 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0095] Example 3: A method for preparing a high-barrier nylon resin

[0096] (1) Add 399.0g (0.98mol) of the diacid obtained in Example 1 and 172.3g (1mol) of decanediamine to 200g (35%) of water and stir to form a salt, to obtain 771.3g of component S-10 salt solution; add 1304.8g (8.93mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine to 885.7g (35%) of water and stir to form a salt, to obtain 3416.2g of nylon MXD-6 salt solution;

[0097] (2) The 771.3g of component S-10 salt solution and 3416.2g of nylon MXD-6 salt solution obtained in step (1) and 10.8g of sodium hypophosphite were added to the reactor. The air in the reactor was replaced with high-purity nitrogen three times and then filled with high-purity nitrogen to 0.15MPa. Melt polycondensation was then carried out: the temperature was first raised to 215℃ and the pressure inside the reactor was maintained at 2.2MPa. The reaction was carried out for 2.0h with one heating and pressure holding. The temperature was then raised to 292℃. During the heating process, the gas was slowly released to maintain the pressure inside the reactor. The pressure was set at 1.8 MPa, and after a second heating and pressure holding reaction for 1.8 h, the pressure inside the reactor was released to bring it down to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 12 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0098] Example 4: A method for preparing a high-barrier nylon resin

[0099] (1) Add 403.0g (0.99mol) of the diacid obtained in Example 2 and 200.4g (1mol) of 1,12-diaminododecane to 229.3g (38%) of water and stir to form a salt, to obtain 832.7g of component S-12 salt solution; add 1289.0g (8.82mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine to 955.6g (38%) of water and stir to form a salt, to obtain 3470.3g of nylon MXD-6 salt solution;

[0100] (2) Add 832.7g of component S-12 salt solution and 3470.3g of nylon MXD-6 salt solution obtained in step (1) and 11.1g of potassium hypophosphate into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 218℃ and maintain the pressure in the reactor at 2.3MPa. Perform a heating and pressure holding reaction for 1.8h. Continue to heat up to 290℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. The pressure was 1.9 MPa, and after a second heating and pressure holding reaction for 1.8 h, the pressure inside the reactor was released to bring it down to atmospheric pressure. After the water in the system was drained, a vacuum pump was used to gradually evacuate the system for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 18 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0101] Example 5: A method for preparing a high-barrier nylon resin

[0102] (1) Add 802.0g (1.97mol) of the diacid obtained in Example 2 and 232.4g (2mol) of hexamethylenediamine to 341.4g (33%) of water and stir to form a salt, to obtain 1375.8g of component S-6 salt solution; add 1585.6g (7.84mol) of sebacic acid and 1089.5g (8mol) of m-phenylenediamine to 882.8g (33%) of water and stir to form a salt, to obtain 3557.9g of nylon MXD-10 salt solution;

[0103] (2) Add 1375.8g of component S-6 salt solution and 3557.9g of nylon MXD-10 salt solution obtained in step (1) and 13.0g of potassium hypophosphate into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 220℃ and maintain the pressure in the reactor at 2.4MPa. Perform a heating and pressure holding reaction for 2.0h. Continue to heat up to 292℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. After applying a pressure of 1.8 MPa and undergoing a second heating and pressure holding reaction for 2.0 h, the pressure inside the reactor was released to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the reactor for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 24 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0104] Example 6: A method for preparing a high-barrier nylon resin

[0105] (1) Add 997.5g (2.45mol) of the diacid obtained in Example 2 and 290.5g (2.5mol) of hexamethylenediamine to 399.3g (31%) of water and stir to form a salt, to obtain 1687.3g of component S-6 salt solution; add 1690.5g (7.35mol) of dodecanoic acid and 1021.4g (7.5mol) of m-phenylenediamine to 840.7g (31%) of water and stir to form a salt, to obtain 3552.6g of nylon MXD-12 salt solution;

[0106] (2) Add 1687.3g of component S-6 salt solution and 3552.6g of nylon MXD-12 salt solution obtained in step (1) and 13.4g of magnesium hypophosphate into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 223℃ and maintain the pressure in the reactor at 2.3MPa. Perform a heating and pressure holding reaction for 2.0h. Continue to heat up to 294℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. After applying a pressure of 1.9 MPa and undergoing a second heating and pressure holding reaction for 2.0 h, the pressure inside the reactor was released to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the reactor for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 24 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0107] Example 7: A method for preparing a high-barrier nylon resin

[0108] (1) 798.0g (1.96mol) of the diacid obtained in Example 3 and 232.4g (2.00mol) of hexamethylenediamine were added to 309.1g (30%) of water and stirred to form a salt, resulting in 1339.5g of component S-6 salt solution; 1289.0g (8.82mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine were added to 754.4g (30%) of water and stirred to form a salt, resulting in 3269.1g of nylon MXD-6 salt solution;

[0109] (2) Add 1339.5g of component S-6 salt solution and 3269.1g of nylon MXD-6 salt solution obtained in step (1) and 13.0g of magnesium hypophosphate into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 220℃ and maintain the pressure in the reactor at 2.2MPa. Perform a heating and pressure holding reaction for 2.0h. Continue to heat up to 296℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. The pressure was set at 1.8 MPa, and after a second heating and pressure holding reaction for 1.8 h, the pressure inside the reactor was released to bring it down to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the system for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min, then evacuated to -0.04 MPa and held for 20 min, and finally evacuated to -0.06 MPa and held for 18 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0110] Example 8: A method for preparing a high-barrier nylon resin

[0111] (1) 1836.2g (4.51mol) of the diacid obtained in Example 3 and 534.5g (4.60mol) of hexamethylenediamine were added to 711.2g (30%) of water and stirred to form a salt, resulting in a 3081.9g component S-6 salt solution; 1289.0g (8.82mol) of adipic acid and 1225.7g (9mol) of m-phenylenediamine were added to 754.4g (30%) of water and stirred to form a salt, resulting in a 3269.1g nylon MXD-6 salt solution;

[0112] (2) Add 3081.9g of component S-6 salt solution and 3269.1g of nylon MXD-6 salt solution obtained in step (1) and 7.9g of magnesium hypophosphate into the reactor. Replace the air in the reactor with high-purity nitrogen three times and fill with high-purity nitrogen to 0.15MPa. Then carry out melt polycondensation: first heat up to 225℃ and maintain the pressure in the reactor at 2.2MPa. Perform a heating and pressure holding reaction for 2.0h. Continue to heat up to 300℃. During the heating process, slowly release the gas to maintain the pressure in the reactor. After a second heating and pressure holding reaction at 1.8 MPa for 2.0 h, the pressure inside the reactor was released to bring it down to atmospheric pressure. After draining the water from the system, a vacuum pump was used to gradually evacuate the reactor for a depressurization reaction: first, the pressure was evacuated to -0.02 MPa and held for 20 min; then, the pressure was evacuated to -0.04 MPa and held for 20 min; finally, the pressure was evacuated to -0.06 MPa and held for 18 min. Then, high-purity nitrogen was introduced to 0.3 MPa, and the material was discharged to obtain high-barrier nylon resin.

[0113] Application Examples of a High Barrier Nylon Resin 1-8

[0114] Examples 1-8 of high-barrier nylon resin were applied to the field of barrier packaging materials technology.

[0115] Comparative Example 1

[0116] (1) Add 659.1g (4.51mol) adipic acid and 534.5g (4.60mol) hexamethylenediamine to 358.1g (30%) water and stir to form a salt, resulting in 1551.7g of nylon 66 salt solution;

[0117] (2) Add 1551.7g of nylon 66 salt solution and 1.9g of sodium hypophosphite obtained in step (1) into the reactor. The subsequent operation is the same as step (2) in Example 8 of the method, and finally nylon 66 resin is obtained.

[0118] Comparative Example 2

[0119] (1) Add 1289.0g (8.82mol) adipic acid and 1225.7g (9mol) m-phenylenediamine to 754.4g (30%) water and stir to form a salt, resulting in 3269.1g of nylon MXD-6 salt solution;

[0120] (2) Add 3269.1g of nylon MXD6 salt solution and 4.1g of sodium hypophosphite obtained in step (1) into the reactor. The subsequent operation is the same as step (2) in Example 8 of the method. Finally, nylon MXD6 resin is obtained.

[0121] To evaluate the mechanical properties, heat resistance, and gas barrier properties of the high-barrier nylon resins of Examples 1-8 and Comparative Examples 1 and 2 of the present invention, tests were conducted under the following conditions:

[0122] Relative viscosity test conditions: The samples of the examples and comparative examples were placed in a vacuum drying oven at 120℃ for 4 hours and a concentrated sulfuric acid solution with a concentration of 0.010 g / mL was prepared. The solution was tested using an automatic viscometer in accordance with the standard GB / T 38138-2019.

[0123] Tensile strength test conditions: The tensile specimens were placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T 1040.2-2006;

[0124] Bending strength test conditions: The bending specimen was placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T 9341-2008;

[0125] Impact strength test conditions: The impact specimen was placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine according to standard GB / T 1043.1-2008;

[0126] Melting point test conditions: Weigh 5-10 mg of the example or comparative sample, heat the sample to 300℃ for 3 min under high-purity nitrogen protection, quench it with liquid nitrogen, then heat the quenched sample to 300℃, cool it to room temperature, and then heat it to 300℃ again. The heating rate is 10℃ / min, referring to standard GB / T 19466.3-2004.

[0127] Initial decomposition temperature test conditions: Weigh 3-8 mg of the sample from the example or comparative example, and under the protection of high-purity nitrogen, heat the sample to 700℃. The temperature corresponding to a 5% weight loss is the initial decomposition temperature, referring to standard GB / T 33047.1-2016.

[0128] Oxygen permeability test standard: The test shall be conducted using the coulometric method of GB / T 19789, "Test for oxygen permeability of plastic films and sheets for packaging materials".

[0129] Water absorption test conditions: Dry the sample of the example or comparative example in an oven at 100°C, cool it in the oven, and test it according to ASTM D570-98 standard;

[0130] The results are shown in Table 1.

[0131] Table 1. Comparison of relevant performance data of the high-barrier nylon resin of the present invention in Examples 1-8 and Comparative Examples 1 and 2.

[0132]

[0133] As shown in Table 1, the high-barrier nylon resins of Examples 1-8 of the present invention exhibit a relative viscosity as high as 2.60, a tensile strength as high as 119 MPa, a flexural strength as high as 196 MPa, and an impact strength as high as 19 kJ / m.2 It has a high melting point of 277.4℃, an initial decomposition temperature of 410.2℃, and an oxygen permeability as low as 1.2mL / (m³). 2 The water absorption rate is as low as 0.13%, indicating that the high-barrier nylon resins of the present invention (Examples 1-8) are suitable for special applications with stringent requirements for film barrier performance and operating temperature. Compared with the nylon 66 resin obtained in Comparative Example 1 and the nylon MXD-6 resin obtained in Comparative Example 2, the high-barrier nylon resin of the present invention (Example 8) significantly reduces oxygen permeability and water absorption rate due to the introduction of rigid, large-planar carbazole units on its molecular backbone. Furthermore, its barrier performance is further improved with the increase of carbazole unit content, indicating that the introduction of diacid in the present invention can significantly improve the thermal stability and oxygen barrier properties of the resulting polymer.

Claims

1. A high-barrier nylon resin, characterized in that: It contains a diacid structure, and the molecular structural formula of the diacid is: ; The molecular structure of the high-barrier nylon resin is as follows: Where a = 6, 9, 10, 12 or 14, b = 4, 8, 10 or 12; the molar ratio of m to n is 10-50:70-190.

2. A method for preparing the high-barrier nylon resin as described in claim 1, characterized in that, Includes the following steps: (1) Add the diacid and aliphatic diamine to water and stir to form a salt to obtain component Sx salt solution; add the aliphatic diacid and m-phenylenediamine to water and stir to form a salt to obtain nylon MXD-y salt solution; (2) The Sx salt solution and nylon MXD-y salt solution obtained in step (1) are added to the reactor along with the catalyst. The air in the reactor is replaced with inert gas and then filled with inert gas. Melt polycondensation is carried out, and then inert gas is filled again. The material is discharged to obtain high-barrier nylon resin.

3. The method for preparing the high-barrier nylon resin according to claim 2, characterized in that: In step (1), in the component Sx salt solution, the molar ratio of the diacid to the aliphatic diamine is 0.96–1.00:1; in the component Sx salt solution, the amount of water used is 30–40% of the total mass of the diacid and the aliphatic diamine; the aliphatic diamine includes one or more of hexamethylenediamine, nonanediamine, decanediamine, 1,12-diaminododecane, or 1,14-diaminotetradecane; in the nylon MXD-y salt solution, the molar ratio of the aliphatic diacid to m-phenylenediamine is 0.96–1.00:1; in the nylon MXD-y salt solution, the amount of water used is 30–40% of the total mass of the aliphatic diacid and m-phenylenediamine; the aliphatic diacid includes one or more of adipic acid, sebacic acid, dodecanoic acid, or tetradecanoic acid.

4. The method for preparing the high-barrier nylon resin according to claim 2 or 3, characterized in that: In step (2), the mass ratio of the component Sx salt solution to the nylon MXD-y salt solution is 1:1 to 6; the amount of catalyst used is 0.1 to 0.5% of the total mass of the component Sx salt solution and the component Sx salt solution; the catalyst includes one or more of sodium hypophosphite, potassium hypophosphite or magnesium hypophosphite.

5. The method for preparing the high-barrier nylon resin according to claim 2 or 3, characterized in that: In step (2), the specific process of melt polycondensation is as follows: first, a heating and pressure holding reaction is carried out, followed by slow gas release and a second heating and pressure holding reaction. After releasing the gas to atmospheric pressure and draining the water from the system, a vacuum is gradually drawn to carry out a decompression reaction. The first heating and pressure holding reaction refers to heating to 210-225℃ and maintaining the pressure inside the reactor at 2.0-2.5MPa for 1.5-2.0h. The slow gas release and second heating and pressure holding reaction refers to continuing to heat to 280-300℃, slowly releasing the gas during the heating process to maintain the pressure inside the reactor at 1.8-2.0MPa for 1.5-2.0h. The gradual vacuum drawing process... The reduced pressure reaction refers to: first, evacuating to -0.01 to -0.03 MPa, maintaining the pressure for 15 to 25 minutes, then evacuating to -0.03 to -0.05 MPa, maintaining the pressure for 15 to 25 minutes, and finally evacuating to -0.05 to -0.07 MPa, maintaining the pressure for 12 to 30 minutes; before the melt polycondensation, the air in the reactor is replaced with inert gas 3 to 4 times and then filled with inert gas to 0.1 to 0.2 MPa; after the melt polycondensation, inert gas is filled to 0.2 to 0.3 MPa; the inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium.

6. The method for preparing the high-barrier nylon resin according to claim 4, characterized in that: In step (2), the specific process of melt polycondensation is as follows: first, a heating and pressure holding reaction is carried out, followed by slow gas release and a second heating and pressure holding reaction. After releasing the gas to atmospheric pressure and draining the water from the system, a vacuum is gradually drawn to carry out a decompression reaction. The first heating and pressure holding reaction refers to heating to 210-225℃ and maintaining the pressure inside the reactor at 2.0-2.5MPa for 1.5-2.0h. The slow gas release and second heating and pressure holding reaction refers to continuing to heat to 280-300℃, slowly releasing the gas during the heating process to maintain the pressure inside the reactor at 1.8-2.0MPa for 1.5-2.0h. The gradual vacuum drawing process... The reduced pressure reaction refers to: first, evacuating to -0.01 to -0.03 MPa, maintaining the pressure for 15 to 25 minutes, then evacuating to -0.03 to -0.05 MPa, maintaining the pressure for 15 to 25 minutes, and finally evacuating to -0.05 to -0.07 MPa, maintaining the pressure for 12 to 30 minutes; before the melt polycondensation, the air in the reactor is replaced with inert gas 3 to 4 times and then filled with inert gas to 0.1 to 0.2 MPa; after the melt polycondensation, inert gas is filled to 0.2 to 0.3 MPa; the inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium.

7. An application of the high-barrier nylon resin as described in claim 1, characterized in that: The high-barrier nylon resin described in claim 1 is used in the field of barrier packaging materials technology.

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