Method for synthesizing high-gloss high-toughness MXD6 resin and application thereof

Abstract

The application discloses a high-gloss high-toughness MXD6 resin synthesis method and application. First, high-concentration m-xylylenediamine aqueous solution, diamine aqueous solution and adipic acid aqueous solution are prepared, and the adipic acid aqueous solution is added dropwise into the diamine aqueous solution or the m-xylylenediamine aqueous solution until the pH of the reaction solution is less than 7, then vacuum concentration and suction filtration are performed to obtain MXD6 salt or nylon salt. Then, pre-polymerization is performed on the MXD6 salt and the nylon salt respectively to obtain MXD6 oligomer and nylon oligomer. Finally, the MXD6 oligomer, the nylon oligomer and a toughening agent are mixed in a certain proportion to perform melt polycondensation, and a high-gloss high-toughness MXD6 synthetic resin is obtained. Through blending modification on the MXD6 synthetic resin prepared in the application, the obtained MXD6 resin modified composite material has higher gloss and toughness, and has higher strength and anti-fiber floating property after glass fibers are added, and can be applied to the fields of plastic parts such as automobile interiors and electronic appliances.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a method for synthesizing and applying high-gloss, high-toughness MXD6 resin. Background Technology

[0002] Nylon MXD6 is a semi-aromatic polyamide formed by the condensation polymerization of m-phenylenediamine and adipic acid. The introduction of benzene rings into its molecular chain endows the material with excellent gas barrier properties, chemical resistance, good flowability, and thermoplasticity. Traditionally, MXD6 has been mainly used in packaging materials. In recent years, with the increasing demands for lightweight materials and performance, MXD6, thanks to its comprehensive performance advantages, has gradually expanded into engineering plastics fields such as automotive parts and electronic appliances.

[0003] However, several key technical bottlenecks still exist in the engineering application of MXD6, limiting its wider use:

[0004] First, MXD6 inherently exhibits low notched impact strength and insufficient toughness. Currently, the common approach is to introduce toughening agents (such as maleic anhydride-grafted polyolefin elastomer POE-g-MAH) to improve this. However, due to the molecular configuration and high crystallinity of MXD6, its compatibility with conventional polyolefin toughening agents and the efficiency of its grafting reaction are far lower than those of PA6 or PA66. Furthermore, the significant difference in melt viscosity between the two leads to difficulties in agent dispersion and unsatisfactory toughening effects. Simultaneously, excessive introduction of toughening agents often significantly sacrifices key mechanical and thermal properties such as tensile strength and heat distortion temperature, and results in a decrease in surface gloss. This problem is particularly prominent in unfilled reinforced MXD6 modified materials.

[0005] Secondly, MXD6 has poor colorability and surface gloss. Due to its specific crystallization behavior and high crystallization rate, the resulting products have high haze. Its dispersion compatibility with conventional nylon carbon black, pigments, or masterbatches is poor, making it difficult for manufactured parts to meet the high blackness, high gloss, and uniform color standards required for applications such as automotive interior parts.

[0006] Finally, in terms of high-performance composite materials, MXD6 exhibits a severe "fiber floating" phenomenon when combined with glass fiber. The benzene ring structure in the MXD6 molecular chain results in strong hydrophobicity and weak chemical bonding with the glass fiber surface wetting agent. Poor interfacial compatibility at glass fiber content exacerbates the fiber floating problem. Conventional anti-fiber floating agents are insufficient to effectively address this issue at conventional addition levels, while excessive use of additives severely impairs the material's mechanical strength and surface scratch resistance.

[0007] From the perspective of material synthesis origin, recent domestic patents related to MXD6 mostly focus on optimizing the synthesis process. For example, patent CN116082632A uses a specific forward and reverse feeding method to form two end-capped intermediates and neutralize them into salts, aiming to reduce intermediate oxidation; CN118599102A involves a solvent purification process for MXD6 salts. These methods mainly focus on controlling and purifying the synthesis process, and do not directly improve the final impact toughness, surface gloss, and fiber float problem of the material.

[0008] Other patents attempt to improve performance through copolymerization or composite modification. For example, CN118027393A discloses a one-pot method for preparing MXD6 / PA66 copolymer resin, and CN116041695A reports copolymerizing MXD6 salt with long-chain nylon salt and nano-montmorillonite to obtain a high-barrier resin. However, these methods fail to delve into the selection of copolymer units, block molecular weight design, and synergistic effects with highly reactive nylon oligomers, thus failing to effectively solve the aforementioned core application challenges such as coloring, gloss, toughness, and anti-fiber floating. Patent CN115368593A proposes a process for directly introducing glass fiber during the MXD6 synthesis stage, which theoretically can improve fiber dispersion and interfacial bonding, reducing fiber floating. However, this method is complex and lacks applicability and flexibility for downstream modification manufacturers.

[0009] Therefore, how to provide a high-gloss, high-toughness MXD6 resin to systematically solve the defects of traditional MXD6 resin such as insufficient toughness, coloring difficulties, low gloss, and insufficient anti-fiber properties during the synthesis stage is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0010] The purpose of this invention is to provide a method for synthesizing and applying high-gloss, high-toughness MXD6 resin, so as to solve at least one of the above-mentioned technical problems.

[0011] To achieve the above objectives, the first aspect of the present invention provides a method for synthesizing high-gloss, high-toughness MXD6 resin, the synthesis method comprising:

[0012] S1. Prepare aqueous solutions of adipic acid with a concentration of 40-60%, m-phenylenediamine with a concentration of 60-90%, and diamine with a concentration of 60-90%, respectively.

[0013] S2. Under the protection of an inert gas, the adipic acid aqueous solution is added dropwise to the m-phenylenediamine aqueous solution until the pH of the reaction solution is <7, and the addition is stopped. The reaction temperature is maintained at 50-60°C. The reaction solution is concentrated under vacuum to obtain a solid-liquid mixture, which is then filtered to obtain MXD6 salt.

[0014] S3. Under the protection of an inert gas, the adipic acid aqueous solution is added dropwise to the diamine aqueous solution until the pH of the reaction solution is <7, and the addition is stopped. The reaction temperature is maintained at 50-60℃. After vacuum concentration, a solid-liquid mixture is obtained, and nylon salt is obtained by suction filtration.

[0015] S4. Dissolve the MXD6 salt in water to obtain an MXD6 salt mixture with a concentration of 75-85%. Under a nitrogen atmosphere, carry out a staged prepolymerization reaction in a polymerization reactor to obtain MXD6 oligomers.

[0016] S5. Dissolve the nylon salt or caprolactam in water to obtain a nylon salt mixture with a concentration of 75-85%, and carry out a staged prepolymerization reaction in a polymerization reactor under a nitrogen atmosphere to obtain nylon oligomers;

[0017] S6. The MXD6 oligomer, the nylon oligomer and the toughening agent are mixed in a mass ratio of (20-80):(20-80):(0-20) and then placed in a screw extruder for melt polycondensation to obtain a high-gloss and high-toughness MXD6 synthetic resin.

[0018] In the first aspect, the diamine aqueous solution includes an aqueous solution of hexamethylenediamine or an aqueous solution of pentanediamine.

[0019] In the first aspect, the toughening agent comprises POE-g-MAH or SEBS-g-MAH.

[0020] In the first aspect, in step S2, obtaining a solid-liquid mixture by vacuum concentration of the reaction solution includes: vacuum concentration of the reaction solution, wherein the vacuum concentration conditions include: a concentration temperature of 60-70°C and a vacuum degree of -0.05 to -0.07 MPa; cooling to 5-25°C at a cooling rate of 3°C / min to obtain a solid-liquid mixture; wherein the solid-liquid mixture is filtered to obtain MXD6 salt, wherein the particle size of the MXD6 salt is 0.2-3 mm.

[0021] In the first aspect, in step S3, the conditions for vacuum concentration include: a concentration temperature of 60-70°C and a vacuum degree of -0.05 to -0.07 MPa; the particle size of the nylon salt is 0.2-3 mm.

[0022] In the first aspect, in step S4, the staged prepolymerization reaction in the polymerization reactor includes: the MXD6 salt mixture is first heated to 160-180°C at a heating rate of 10°C / min and a pressure of 1.2-1.5 MPa in the polymerization reactor, and the reaction is maintained at the same temperature and pressure for 1 hour; then the temperature is further increased to 210-230°C at a heating rate of 10°C / min and a pressure of 1.6-2.0 MPa, and the reaction is maintained at the same temperature and pressure for 1 hour; then the mixture is allowed to cool naturally to room temperature, filtered, and dried to obtain the MXD6 oligomer.

[0023] In the first aspect, in step S5, the staged prepolymerization reaction in the polymerization reactor includes: the nylon salt mixture is first heated to 170-200°C at a heating rate of 10°C / min and a pressure of 1.2-1.5 MPa in the polymerization reactor, and the reaction is maintained at the same temperature and pressure for 1 hour; then the temperature is further increased to 230-250°C at a heating rate of 10°C / min and a pressure of 1.8-2.2 MPa, and the reaction is maintained at the same temperature and pressure for 1 hour; then the mixture is allowed to cool naturally to room temperature, filtered, and dried to obtain the nylon oligomer.

[0024] In the first aspect, in step S6, the process parameters of the screw extruder include: temperature of 170-260℃, vacuum degree of -0.03 to -0.08MPa, rotation speed of 15-40rpm, and screw residence time of 5-15min.

[0025] The second aspect of this invention provides a method for preparing a high-gloss, high-toughness MXD6 resin-modified composite material. The method includes: preparing MXD6 synthetic resin according to the high-gloss, high-toughness MXD6 resin synthesis method described in the first aspect; weighing each component of the raw materials, wherein each component, by weight percentage, includes: 28-98% MXD6 synthetic resin, 0-70% glass fiber, 1.5% processing aid, and 0.5-1% colorant, wherein the processing aid consists of an antioxidant and a release agent; placing the MXD6 synthetic resin, the processing aid, and the colorant in a high-speed mixing tank for premixing to obtain a premix; adding the premix from the main feed port of a twin-screw extruder and conveying it into the screw cavity; adding the glass fiber from the side feed port and conveying it into the screw cavity; and after shear melt blending, extruding and granulating to obtain the MXD6 resin-modified composite material.

[0026] The third aspect of this invention provides an application of MXD6 resin modified composite material in automotive interiors and plastic parts for electronic appliances, wherein the MXD6 resin modified composite material is prepared by the preparation method of high-gloss and high-toughness MXD6 resin modified composite material described in the second aspect.

[0027] Beneficial effects:

[0028] This invention provides a method for synthesizing high-gloss, high-toughness MXD6 resin. First, high-concentration aqueous solutions of adipic acid, m-phenylenediamine, and diamine are prepared. Nitrogen or an inert gas is used to displace oxygen from the solutions, reducing the oxidation of the monomers diacid or diamine. Then, under inert gas protection, aqueous adipic acid is added dropwise to the m-phenylenediamine or diamine solutions until the pH of the reaction solution is <7, at which point the addition is stopped. The reaction temperature is maintained at 50-60°C. Part of the solvent is removed by vacuum concentration. A solid-liquid mixture is obtained, which, after filtration, yields MXD6 salt or nylon salt. Then, the MXD6 salt is dissolved in water and prepolymerized in a polymerization reactor to obtain MXD6 oligomers. Nylon salt or caprolactam is dissolved in water and prepolymerized in a polymerization reactor to obtain nylon oligomers. Finally, the MXD6 oligomers, nylon oligomers, and toughening agent are mixed in a mass ratio of (20-80):(20-80):(0-20) and then melt-polymerized in a screw extruder to obtain a high-gloss, high-toughness MXD6 synthetic resin. This invention, through molecular design, modifies the block unit polymer by controlling the salt particle size and oligomer molecular weight during the synthesis stage, thereby copolymerizing and modifying the MXD6 resin to achieve high toughness, high gloss, and anti-fiber properties while retaining barrier properties and flowability. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A flowchart of a method for synthesizing high-gloss, high-toughness MXD6 resin provided by the present invention;

[0031] Figure 2 These are images showing the appearance of the MXD6 resin-modified composite materials in the embodiments and comparative examples of this invention. Detailed Implementation

[0032] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0033] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0035] like Figure 1 As shown, the present invention provides a method for synthesizing high-gloss, high-toughness MXD6 resin, the synthesis method comprising:

[0036] S1. Prepare aqueous solutions of adipic acid with a concentration of 40-60%, m-phenylenediamine with a concentration of 60-90%, and diamine with a concentration of 60-90%, respectively.

[0037] S2. Under the protection of an inert gas, the adipic acid aqueous solution is added dropwise to the m-phenylenediamine aqueous solution until the pH of the reaction solution is <7, and the addition is stopped. The reaction temperature is maintained at 50-60°C. The reaction solution is concentrated under vacuum to obtain a solid-liquid mixture, which is then filtered to obtain MXD6 salt.

[0038] S3. Under the protection of an inert gas, the adipic acid aqueous solution is added dropwise to the diamine aqueous solution until the pH of the reaction solution is <7, and the addition is stopped. The reaction temperature is maintained at 50-60℃. After vacuum concentration, a solid-liquid mixture is obtained, and nylon salt is obtained by suction filtration.

[0039] S4. Dissolve the MXD6 salt in water to obtain an MXD6 salt mixture with a concentration of 75-85%. Under a nitrogen atmosphere, carry out a staged prepolymerization reaction in a polymerization reactor to obtain MXD6 oligomers.

[0040] S5. Dissolve the nylon salt or caprolactam in water to obtain a nylon salt mixture with a concentration of 75-85%, and carry out a staged prepolymerization reaction in a polymerization reactor under a nitrogen atmosphere to obtain nylon oligomers;

[0041] S6. The MXD6 oligomer, the nylon oligomer and the toughening agent are mixed in a mass ratio of (20-80):(20-80):(0-20) and then placed in a screw extruder for melt polycondensation to obtain a high-gloss and high-toughness MXD6 synthetic resin.

[0042] Specifically, the present invention provides a method for synthesizing high-gloss, high-toughness MXD6 resin. First, high-concentration aqueous solutions of adipic acid, m-phenylenediamine, and diamine are prepared. Nitrogen or an inert gas is used to displace oxygen from the solutions to reduce the oxidation of the monomers diacid or diamine. Then, under inert gas protection, aqueous adipic acid is added dropwise to the m-phenylenediamine or diamine solutions until the pH of the reaction solution is <7, at which point the addition is stopped. The reaction temperature is maintained at 50-60°C, and the resin is concentrated under vacuum to remove some of the oxidized components. Solvent separation yields a solid-liquid mixture, which, after filtration, yields MXD6 salt or nylon salt. The MXD6 salt is then dissolved in water and prepolymerized in a polymerization reactor to obtain MXD6 oligomers. Nylon salt or caprolactam is dissolved in water and prepolymerized in a polymerization reactor to obtain nylon oligomers. Finally, the MXD6 oligomers, nylon oligomers, and toughening agent are mixed in a mass ratio of (20-80):(20-80):(0-20) and then melt-polymerized in a screw extruder to obtain a high-gloss, high-toughness MXD6 synthetic resin. This invention modifies the MXD6 resin by controlling the molecular weight of the oligomers during the synthesis stage through molecular design, thereby achieving high toughness, high gloss, and anti-fiber properties while retaining barrier properties and flowability.

[0043] In some possible embodiments, the diamine aqueous solution includes an aqueous solution of hexamethylenediamine or an aqueous solution of pentanediamine.

[0044] In this application, the diamine aqueous solution includes hexamethylenediamine aqueous solution or pentanediamine aqueous solution. Nylon 66 salt is prepared by reacting adipic acid aqueous solution with hexamethylenediamine aqueous solution, and Nylon 56 salt is prepared by reacting adipic acid aqueous solution with pentanediamine aqueous solution. At the same time, preparing a high concentration of diamine or diacid aqueous solution is also to improve the reaction rate.

[0045] In some possible embodiments, the toughening agent includes POE-g-MAH or SEBS-g-MAH.

[0046] In this application, the toughening agent includes POE-g-MAH or SEBS-g-MAH. By adding the toughening agent to the synthetic resin, the toughness of the resin can be further improved, and it is beneficial to improve the compatibility with processing aids and pigments, thereby improving the overall performance of MXD6 composite materials.

[0047] In some possible embodiments, step S2, obtaining a solid-liquid mixture by vacuum concentration of the reaction solution includes: vacuum concentration of the reaction solution, wherein the vacuum concentration conditions include: concentration temperature of 60-70°C, vacuum degree of -0.05 to -0.07 MPa; cooling to 5-25°C at a cooling rate of 3°C / min to obtain a solid-liquid mixture; wherein the solid-liquid mixture is filtered to obtain MXD6 salt, wherein the particle size of the MXD6 salt is 0.2-3 mm.

[0048] In this application, adipic acid aqueous solution is added dropwise to an aqueous solution of m-phenylenediamine until the pH of the reaction solution is <7. Since this dropwise addition process is an exothermic reaction, excessively rapid dropping or high reaction temperature will lead to the oxidative decomposition of m-phenylenediamine monomer. Therefore, it is necessary to control the dropping rate and reaction temperature, and to ensure that the reaction proceeds steadily at a suitable temperature. When the preset pH value is reached, the reaction is stopped, and the reaction solution is concentrated under vacuum to remove excess solvent, allowing MXD6 salt to precipitate from the solution. At the same time, by controlling the cooling rate, the particle size of MXD6 salt can be effectively controlled within 0.2-3 mm, thereby improving filtration efficiency, reducing the residual amount of salt and monomer in the filtrate, and increasing the yield.

[0049] In some possible embodiments, in step S3, the conditions for vacuum concentration include: a concentration temperature of 60-70°C and a vacuum degree of -0.05 to -0.07 MPa; the particle size of the nylon salt is 0.2-3 mm.

[0050] Similarly, when preparing nylon salts, it is necessary to control the dropping rate of adipic acid aqueous solution, reaction temperature, vacuum concentration temperature, and cooling rate to improve the yield of nylon salts.

[0051] In some possible embodiments, in step S4, the staged prepolymerization reaction in the polymerization reactor includes: the MXD6 salt mixture is first heated to 160-180°C at a heating rate of 10°C / min and a pressure of 1.2-1.5 MPa in the polymerization reactor, and the reaction is maintained at the same temperature and pressure for 1 hour; then the temperature is further increased to 210-230°C at a heating rate of 10°C / min and a pressure of 1.6-2.0 MPa, and the reaction is maintained at the same temperature and pressure for 1 hour; then the mixture is allowed to cool naturally to room temperature, filtered, and dried to obtain the MXD6 oligomer.

[0052] In this application, MXD6 oligomers are prepared using a two-stage stepwise process to control the molecular weight and distribution of the MXD6 prepolymer. First, polymerization is initiated by heating to 160-180℃ at a rate of 10℃ / min and a pressure of 1.2-1.5 MPa, and holding the reaction at this temperature and pressure for 1 hour. Then, polymerization is increased by heating to 210-230℃ at a rate of 10℃ / min and a pressure of 1.6-2.0 MPa, and holding the reaction at this temperature and pressure for 1 hour. By controlling the heating rate, reaction temperature, and pressure, the molecular weight of the MXD6 oligomer is controlled. The structural formula of the MXD6 oligomer is as follows:

[0053] .

[0054] In some possible embodiments, in step S5, the staged prepolymerization reaction in the polymerization reactor includes: the nylon salt mixture is first heated to 170-200°C at a heating rate of 10°C / min and a pressure of 1.2-1.5 MPa, and the reaction is maintained at the same temperature and pressure for 1 hour; then the temperature is further increased to 230-250°C at a heating rate of 10°C / min and a pressure of 1.8-2.2 MPa, and the reaction is maintained at the same temperature and pressure for 1 hour; then the mixture is allowed to cool naturally to room temperature, filtered, and dried to obtain the nylon oligomer.

[0055] Similarly, a two-stage prepolymerization reaction of nylon salts yields nylon oligomers; more specifically, when adipic acid aqueous solution is added dropwise to hexamethylenediamine aqueous solution, a prepolymerization reaction yields PA66 oligomers, the structural formula of which is as follows:

[0056] ;

[0057] When adipic acid aqueous solution is added dropwise to pentamethylenediamine aqueous solution, a prepolymerization reaction yields PA56 oligomer, the structural formula of which is as follows:

[0058] ;

[0059] When caprolactam is dissolved in water and subjected to a prepolymerization reaction, PA6 oligomer is obtained, with the following structural formula:

[0060] ;

[0061] Where n is the degree of polymerization; corresponding oligomers are obtained by prepolymerizing adipic acid with different diamine monomers.

[0062] In some possible embodiments, in step S6, the process parameters of the screw extruder include: temperature of 170-260℃, vacuum degree of -0.03 to -0.08MPa, rotation speed of 15-40rpm, and screw residence time of 5-15min.

[0063] In this application, MXD6 oligomers are mixed with different nylon oligomers and / or POE-g-MAH or SEBS-g-MAH in a certain proportion and then placed in a screw extruder for blending melt polycondensation. The molecular weight and oxidation degree of the MXD6 synthetic resin are controlled by controlling the process parameters of the screw extruder. Specifically, the blending polycondensation is carried out in the screw extruder with low shear, low speed and low processing temperature.

[0064] When MXD6 oligomers and PA66 oligomers are blended and polycondensed, MXD6-PA66 synthetic resin is obtained, with the following structural formula:

[0065] ;

[0066] When MXD6 oligomer is blended and polycondensed with PA66 oligomer and PA6 oligomer, MXD6-PA66-PA6 synthetic resin is obtained, with the following structural formula:

[0067] ;

[0068] When MXD6 oligomers are blended and polycondensed with toughening agents (POE-g-MAH or SEBS-g-MAH), MXD6-toughening agent synthetic resin is obtained, with the following structural formula:

[0069] ;

[0070] When MXD6 oligomer is blended and polycondensed with PA66 oligomer and toughening agent (POE-g-MAH or SEBS-g-MAH), MXD6-PA66-toughening agent synthetic resin is obtained, with the following structural formula:

[0071] ;

[0072] When MXD6 oligomer is blended and polycondensed with PA66 oligomer, PA6 oligomer, and toughening agent (POE-g-MAH or SEBS-g-MAH), an MXD6-PA66-PA6-toughening agent synthetic resin is obtained, with the following structural formula:

[0073] ;

[0074] Where n is the degree of aggregation;

[0075] Similarly, when MXD6 oligomers are blended and polycondensed with different oligomers or toughening agents, different types and properties of MXD6 synthetic resins can be obtained. Furthermore, the toughening agent segments are not limited to the end-capped parts of the polymer but can also be located at any block in the polymer. The MXD6 synthetic resin prepared by this method exhibits good flowability and barrier properties, and is also easy to color, has high gloss, excellent toughness, and good resistance to fiber floating.

[0076] Based on a general inventive concept, this invention provides a method for preparing a high-gloss, high-toughness MXD6 resin modified composite material, the preparation method comprising:

[0077] MXD6 synthetic resin was prepared according to the high-gloss, high-toughness MXD6 resin synthesis method described in the first aspect;

[0078] Weigh each component of the raw material, which, by weight percentage, includes: 28-98% of the MXD6 synthetic resin, 0-70% of glass fiber, 1.5% of processing aids, and 0.5-1% of color powder, wherein the processing aids consist of antioxidants and release agents;

[0079] The MXD6 synthetic resin, the processing aid, and the color powder are placed in a high-speed mixing tank for premixing to obtain a premix.

[0080] The premix is ​​added from the main feed port of the twin-screw extruder and conveyed into the screw cavity. The glass fiber is added from the side feed port and conveyed into the screw cavity. After shearing and melt blending, the mixture is extruded and granulated to obtain the MXD6 resin modified composite material.

[0081] Specifically, different types of MXD6 synthetic resins are prepared according to the above synthesis method. After adding a small amount of processing aids and color powder to the MXD6 synthetic resin for blending modification, the gloss and toughness of the material can be further improved. Alternatively, adding glass fiber, processing aids and color powder to the MXD6 synthetic resin can not only improve the gloss and toughness of the material, but also improve the strength of the material.

[0082] This application improves the gloss, toughness, anti-fiber properties, and strength of MXD6 synthetic resin by adding simple additives, making it applicable to the automotive, electronics, and other fields, especially suitable for high-gloss interior panels in high-end automobiles.

[0083] Based on a general inventive concept, the present invention also provides an application of MXD6 resin modified composite material in automotive interiors and plastic parts for electronic appliances, wherein the MXD6 resin modified composite material is prepared by the preparation method of high-gloss and high-toughness MXD6 resin modified composite material described in the second aspect.

[0084] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0085] The specific preparation process of the oligomers used in the examples and comparative examples is as follows:

[0086] (1) Preparation steps of MXD6 oligomers:

[0087] Deionized water was added to 2.04 kg of m-phenylenediamine to prepare a 70% m-phenylenediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution.

[0088] Under conditions of cold water circulation and stirring, a 50% adipic acid aqueous solution is added dropwise to a 70% m-phenylenediamine aqueous solution at a dropping rate of 0.3 kg / min until the pH of the reaction solution is <7, at which point the dropping is stopped. The reaction temperature during the dropping process needs to be controlled at 50-60℃. After the dropping is completed, the reaction solution is concentrated under vacuum to remove excess solvent, reducing the volume of the reaction solution by 1 / 3-1 / 2. The concentration temperature is 60-70℃, and the vacuum degree is -0.05 to -0.07 MPa. After vacuum concentration, the temperature is lowered to 10±2℃ at a cooling rate of 3℃ / min. Solid particles precipitate from the reaction solution, resulting in a solid-liquid mixture. After filtration, MXD6 salt is obtained, with a particle size of 0.5-3 mm.

[0089] MXD6 salt was dissolved in water to obtain an MXD6 salt mixture with a concentration of 75-85%. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 170±10℃ and the pressure was 1.2±0.2MPa in a polymerization reactor at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 220±10℃ and the pressure was 1.8±0.2MPa at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain MXD6 oligomers with a moisture content of less than 0.2%.

[0090] (2) Preparation steps of PA66 oligomers:

[0091] Deionized water was added to 2.32 kg of hexamethylenediamine to prepare a 70% hexamethylenediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution.

[0092] Under conditions of cold water circulation and stirring, a 50% adipic acid aqueous solution is added dropwise to a 70% hexamethylenediamine aqueous solution at a dropping rate of 0.3 kg / min until the pH of the reaction solution is <7, at which point the dropping is stopped. The reaction temperature during the dropping process needs to be controlled at 50-60℃. After the dropping is completed, the reaction solution is concentrated under vacuum to remove excess solvent, reducing the volume of the reaction solution by 1 / 3-1 / 2. The concentration temperature is 60-70℃, and the vacuum degree is -0.05 to -0.07 MPa. After vacuum concentration, the temperature is lowered to 10±2℃ at a cooling rate of 3℃ / min. Solid particles precipitate from the reaction solution, resulting in a solid-liquid mixture. After filtration, PA66 salt is obtained, with a particle size of 0.5-3 mm.

[0093] PA66 salt was dissolved in water to obtain a PA66 salt mixture with a concentration of 75-85%. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 180±10℃ and the pressure was 1.3±0.2MPa in a polymerization reactor at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 240±10℃ and the pressure was 2.0±0.2MPa at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain PA66 oligomers with a moisture content of less than 0.2%.

[0094] (3) Preparation steps of PA6 oligomers:

[0095] Caprolactam was dissolved in water to make the pH of the solution less than 7 and its concentration controlled at 75-85%. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 180±10℃ and the pressure was 1.3±0.2MPa in a polymerization reactor at a rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 240±10℃ and the pressure was 2.0±0.2MPa at a rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain PA6 oligomers with a moisture content of less than 0.2%.

[0096] (4) Preparation steps of PA56 oligomers:

[0097] Deionized water was added to 2.04 kg of pentanediamine to prepare a 70% pentanediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution.

[0098] Under conditions of cold water circulation and stirring, a 50% adipic acid aqueous solution is added dropwise to a 70% pentanediamine aqueous solution at a dropping rate of 0.3 kg / min until the pH of the reaction solution is <7, at which point the dropping is stopped. The reaction temperature during the dropping process needs to be controlled at 50-60℃. After the dropping is completed, the reaction solution is concentrated under vacuum to remove excess solvent, reducing the volume of the reaction solution by 1 / 3-1 / 2. The concentration temperature is 60-70℃, and the vacuum degree is -0.05 to -0.07 MPa. After vacuum concentration, the temperature is lowered to 10±2℃ at a cooling rate of 3℃ / min. Solid particles precipitate from the reaction solution, resulting in a solid-liquid mixture. After filtration, PA56 salt is obtained, with a particle size of 0.5-3 mm.

[0099] PA56 salt was dissolved in water to obtain an MXD6 salt mixture with a concentration of 75-85%. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 180±10℃ and the pressure was 1.3±0.2MPa in a polymerization reactor at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 240±10℃ and the pressure was 2.0±0.2MPa at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain PA56 oligomers with a moisture content of less than 0.2%.

[0100] In this application, MXD6 oligomers can be melt polycondensed with PA66 oligomers and / or PA6 oligomers and / or PA56 oligomers and / or toughening agents in a screw extrusion process, and the extruded strips can be cooled and pelletized to obtain MXD6 synthetic resins with different structures. The formulation ratios are shown in Table 1. In this application, the formulation ratio of MXD6 synthetic resins is not limited to two-component and three-component formulations, but can also be four-component or five-component formulations.

[0101] Table 1 Formulation composition of MXD6 synthetic resin

[0102]

[0103] Comparative Example 3

[0104] This comparative example provides a method for preparing MXD6 / PA66 copolymer, specifically including the following steps:

[0105] Deionized water was added to 2.04 kg of m-phenylenediamine to prepare a 70% m-phenylenediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution; under the conditions of cold water circulation and stirring, the 50% adipic acid aqueous solution was added dropwise to the 70% m-phenylenediamine aqueous solution, and the reaction temperature was controlled at 50℃; after the addition was completed, the reaction solution was concentrated under vacuum to obtain crude MXD6 salt;

[0106] Deionized water was added to 2.32 kg of hexamethylenediamine to prepare a 70% hexamethylenediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution; under the conditions of cold water circulation and stirring, the 50% adipic acid aqueous solution was added dropwise to the 70% hexamethylenediamine aqueous solution, and the reaction temperature was controlled at 50℃; after the addition was completed, the reaction solution was concentrated under vacuum to obtain crude PA66 salt.

[0107] MXD6 crude salt was dissolved in water to obtain a 75% MXD6 salt mixture. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 170±10℃ and 1.2±0.2MPa in a polymerization reactor at a rate of 10℃ / min, and the reaction was maintained at this temperature and pressure for 1 hour. The temperature was then increased to 220±10℃ and 1.8±0.2MPa at a rate of 10℃ / min, and the reaction was maintained at this temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain an MXD6 polymer with a moisture content of less than 0.2%.

[0108] PA66 crude salt was dissolved in water to obtain a PA66 salt mixture with a concentration of 75%. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 180±10℃ and the pressure was 1.3±0.2MPa in a polymerization reactor at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 240±10℃ and the pressure was 2.0±0.2MPa at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature. The reactants were filtered, and the filter cake was dried under vacuum for 24 hours to obtain PA66 polymer with a moisture content of less than 0.2%.

[0109] 50 parts by weight of MXD6 polymer and 50 parts by weight of PA66 polymer were weighed and placed in a screw extruder for melt polycondensation to obtain MXD6 / PA66 copolymer.

[0110] Comparative Example 4

[0111] This comparative example provides a method for preparing MXD6 / PA66 copolymer, specifically including the following steps:

[0112] 2.04 kg of m-phenylenediamine was added to deionized water to prepare a 70% m-phenylenediamine aqueous solution; 2.92 kg of adipic acid was added to deionized water to prepare a 50% adipic acid aqueous solution; under the conditions of cold water circulation and stirring, the 50% adipic acid aqueous solution was added dropwise to the 70% m-phenylenediamine aqueous solution, and the reaction temperature was controlled at 50℃. The reaction was carried out for 2 hours to obtain an MXD6 salt solution. After the addition was completed, the reaction solution was concentrated under vacuum to obtain crude MXD6 salt.

[0113] Deionized water was added to 2.32 kg of hexamethylenediamine to prepare a 70% hexamethylenediamine aqueous solution; deionized water was added to 2.92 kg of adipic acid to prepare a 50% adipic acid aqueous solution; under the conditions of cold water circulation and stirring, the 50% adipic acid aqueous solution was added dropwise to the 70% hexamethylenediamine aqueous solution, and the reaction temperature was controlled at 50℃. The reaction was carried out for 2 hours to obtain a PA66 salt solution. After the addition was completed, the reaction solution was concentrated under vacuum to obtain crude PA66 salt.

[0114] 50 parts by weight of crude MXD6 salt and 50 parts by weight of crude PA66 salt were weighed and dissolved in water to obtain a 75% concentration mixture of crude MXD6 salt and crude PA66 salt solutions. The mixture was stirred, evacuated, and purged with nitrogen three times to remove air. The temperature was increased to 180±10℃ and the pressure was 1.3±0.2MPa in a polymerization reactor at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The temperature was then increased to 240±10℃ and the pressure was 2.0±0.2MPa at a heating rate of 10℃ / min, and the reaction was maintained at the same temperature and pressure for 1 hour. The mixture was then allowed to cool naturally to room temperature, filtered, and the filter cake was dried under vacuum for 24 hours to obtain a low molecular weight MXD6 / PA66 copolymer with a moisture content of less than 0.2%.

[0115] Low molecular weight MXD6 / PA66 copolymers are melt polycondensed in a screw extruder to obtain high molecular weight MXD6 / PA66 copolymers.

[0116] The performance of the MXD6 synthetic resins of Examples 1-18 and Comparative Examples 1-4 was tested, and the test results are shown in Table 2:

[0117] Table 2 Test results of MXD6 synthetic resin

[0118]

[0119] This invention provides a method for preparing a high-gloss, high-toughness MXD6 resin modified composite material, specifically including the following steps:

[0120] (1) Using the MXD6 synthetic resin prepared above as raw material, glass fiber, processing aid and color powder are added in proportion, which includes, by weight percentage: 28-98% MXD6 synthetic resin, 0-70% glass fiber, 1.5% processing aid and 0.5-1% color powder, wherein the processing aid is composed of antioxidant and release agent;

[0121] (2) Place MXD6 synthetic resin, processing aids and color powder in a high-speed mixing tank for premixing to obtain a premix;

[0122] (3) The premix is ​​added from the main feed port of the twin-screw extruder and conveyed into the screw cavity. Glass fiber is added from the side feed port and conveyed into the screw cavity. After shearing and melting blending, extrusion granulation is performed to obtain MXD6 resin modified composite material.

[0123] The MXD6 synthetic resins prepared in Examples 1-18 and Comparative Examples 1-4 were subjected to composite modification according to the above experimental steps to obtain modified composite materials with better performance. The modifiers included glass fiber, color powder, and processing aids, wherein the processing aids consisted of antioxidants and release agents. Taking the MXD6-PA66-toughening agent synthetic resin prepared in Example 16 as an example, modifiers were added to it to prepare modified composite materials, and the blending modification formulations are shown in Table 3.

[0124] Table 3 Formulation composition of MXD6 resin modified composite materials

[0125]

[0126] The performance of the MXD6 resin-modified composite materials prepared in Examples 19-24 and Comparative Examples 5-6 was tested, and the test results are shown in Table 4:

[0127] Table 4 Test results of MXD6 resin modified composite materials

[0128]

[0129] As can be seen from the experimental data in Tables 1 and 2, the MXD6 synthetic resin prepared by copolymerizing PA66 oligomer, PA6 oligomer, PA56 oligomer and / or toughening agent (POE-g-MAH or SEBS-g-MAH) with MXD6 oligomer has better mechanical properties than that of MXD6 resin alone, and also has higher gloss.

[0130] Compared to Example 7, Comparative Examples 3 and 4 used the same mass ratio for blending modification of MXD6 synthetic resin. In Comparative Example 3, the particle size of the MXD6 and PA66 crude salts was not strictly controlled during the experiment, making it easy for the terminal amino groups to oxidize during polycondensation in aqueous solution. This resulted in a decrease in the overall mechanical properties of the MXD6 / PA66 copolymer and a yellow appearance. In Comparative Example 4, a homogeneous copolymerization of MXD6 and PA66 salt solutions was used, resulting in a random copolymer of MXD6 / PA66. The m-phenylenediamine and hexamethylenediamine were randomly distributed in the molecular chain, causing the PA66 segments to fail to provide flexibility (reduced tensile and impact properties). Furthermore, the copolymer was in a disordered state, leading to a decrease in flexural strength, flexural modulus, and gloss (yellowish appearance and transparency), thus reducing the overall performance of the prepared MXD6 / PA66 copolymer.

[0131] From Table 3-4 and Figure 2 Experimental data show that blending modification of the MXD6 synthetic resin prepared by the synthesis method provided in this application can further improve the colorability (high blackness) and gloss of the modified composite material. Furthermore, the addition of glass fibers to the material results in a modified composite material with higher strength and excellent low fiber float rate. In other words, the MXD6 synthetic resin prepared in this application possesses advantages such as good flowability, barrier properties, toughness, high gloss, and ease of coloring; the MXD6 resin-modified composite material prepared in this application exhibits higher toughness, gloss, strength, and resistance to fiber float; it can be widely used in the automotive, electronics, and other fields, especially suitable for high-gloss interior panels in high-end automobiles.

[0132] In summary, this application systematically addresses the shortcomings of traditional MXD6 resins during the synthesis stage, such as insufficient toughness, coloring difficulties, low gloss, and severe fiber floating in glass fiber reinforced composites. By screening the types of copolymer units and controlling the molecular weight of the blocks, and by using nylon oligomers with higher reactivity and copolymerizing with maleic anhydride grafted elastomers, the MXD6 units are modified to have better interfacial compatibility and synergistic reinforcement effects. This breaks through the technical barriers of MXD6 synthetic resin in high-end engineering applications and achieves a comprehensive performance improvement of "1+1>2".

[0133] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0134] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0135] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A process for the synthesis of high gloss high tenacity MXD6 resin, characterized in that, The synthesis method comprises: S1, respectively preparing a 40-60% adipic acid aqueous solution, a 60-90% m-xylylenediamine aqueous solution and a 60-90% diamine aqueous solution; S2, under inert gas protection, adding the adipic acid aqueous solution dropwise into the m-xylylenediamine aqueous solution until the pH of the reaction solution is less than 7, and maintaining the reaction temperature at 50-60℃, and then vacuum concentrating the reaction solution to obtain a solid-liquid mixture, and then filtering the solid-liquid mixture to obtain MXD6 salt; S3, under inert gas protection, adding the adipic acid aqueous solution dropwise into the diamine aqueous solution until the pH of the reaction solution is less than 7, and maintaining the reaction temperature at 50-60℃, and then vacuum concentrating the reaction solution to obtain a solid-liquid mixture, and then filtering the solid-liquid mixture to obtain nylon salt; S4, dissolving the MXD6 salt in water to obtain a 75-85% MXD6 salt mixture, and then performing a staged prepolymerization reaction in a polymerization kettle under a nitrogen atmosphere to obtain MXD6 oligomer; S5, dissolving the nylon salt or caprolactam in water to obtain a 75-85% nylon salt mixture, and then performing a staged prepolymerization reaction in a polymerization kettle under a nitrogen atmosphere to obtain nylon oligomer; S6, mixing the MXD6 oligomer, the nylon oligomer and a toughening agent according to a mass ratio of (20-80):(20-80):(0-20), and then placing the mixture in a screw extruder to perform melt polycondensation, thereby obtaining high-gloss high-toughness MXD6 synthetic resin. The diamine aqueous solution comprises a hexamethylene diamine aqueous solution or a pentanediamine aqueous solution.

2. The process for the synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, The toughening agent comprises POE-g-MAH or SEBS-g-MAH.

3. The process for the synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, In step S2, vacuum concentrating the reaction solution to obtain a solid-liquid mixture comprises: vacuum concentrating the reaction solution, wherein the vacuum concentration is performed at a concentration temperature of 60-70℃ and a vacuum degree of -0.05 to -0.07 MPa; cooling the reaction solution to 5-25℃ at a cooling rate of 3℃ / min to obtain a solid-liquid mixture; wherein the solid-liquid mixture is filtered to obtain MXD6 salt, and the particle size of the MXD6 salt is 0.2-3 mm.

4. The process for synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, In step S3, the vacuum concentration is performed at a concentration temperature of 60-70℃ and a vacuum degree of -0.05 to -0.07 MPa, and the particle size of the nylon salt is 0.2-3 mm.

5. The process for synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, In step S4, the staged prepolymerization reaction in the polymerization kettle comprises: firstly, heating the MXD6 salt mixture in the polymerization kettle to 160-180℃ at a heating rate of 10℃ / min under a pressure of 1.2-1.5 MPa, and maintaining the temperature and pressure for 1 h; then, continuously heating the mixture to 210-230℃ at a heating rate of 10℃ / min under a pressure of 1.6-2.0 MPa, and maintaining the temperature and pressure for 1 h; and then, naturally cooling the mixture to room temperature, filtering and drying the mixture to obtain MXD6 oligomer.

6. The process for synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, In step S5, the staged prepolymerization reaction in the polymerization kettle comprises: The nylon salt mixture is first heated to 170-200 DEG C at a heating rate of 10 DEG C / min in a polymerization kettle, the pressure is 1.2-1.5 MPa, and the reaction is carried out for 1 h under the condition of keeping temperature and pressure; then the temperature is continuously increased to 230-250 DEG C at a heating rate of 10 DEG C / min, the pressure is 1.8-2.2 MPa, and the reaction is carried out for 1 h under the condition of keeping temperature and pressure; then the temperature is naturally decreased to room temperature, and the nylon oligomer is obtained after filtration and drying.

7. The process for synthesis of high gloss high tenacity MXD6 resin as claimed in claim 1, wherein, In step S6, the process parameters of the screw extruder include: temperature of 170-260 DEG C, vacuum degree of-0.03 to-0.08 MPa, rotation speed of 15-40 rpm, and screw residence time of 5-15 min.

8. A method for producing a high-gloss high-toughness MXD6 resin modified composite material, characterized by, The preparation method comprises: The MXD6 synthetic resin is prepared by the high-gloss high-toughness MXD6 resin synthesis method according to any one of claims 1-7; The raw materials are weighed, and the raw materials comprise, by weight percentage: the MXD6 synthetic resin 28-98%, glass fiber 0-70%, processing aid 1.5%, and color powder 0.5-1%, wherein the processing aid is composed of antioxidant and release agent; The MXD6 synthetic resin, the processing aid, and the color powder are pre-mixed in a high-speed mixing barrel to obtain a premix; The premix is added from the main feeding port of the twin-screw extruder and is conveyed into the screw cavity; when the formula contains glass fiber, the glass fiber is added from the side feeding port and is conveyed into the screw cavity; after shearing, melting, and blending, the MXD6 resin modified composite material is obtained through extrusion and granulation.

9. Use of MXD6 resin modified composite in plastic parts of automotive interior, electronics and electricals characterized in that, The MXD6 resin modified composite material is prepared by the preparation method of the high-gloss high-toughness MXD6 resin modified composite material according to claim 8.

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