High temperature resistant nylon copolymer and method for preparing the same

Abstract

The application discloses a kind of high-temperature-resistant nylon copolymer and preparation method thereof, belong to high-temperature-resistant nylon field.The preparation method provided by the application includes the following steps: binary acid, binary amine, antioxidant, end-capping agent and catalyst are added into polymerization kettle to carry out salt making reaction, obtain salt solution;The salt solution is cooled, filtered, dried, and high-temperature-resistant nylon salt is obtained;High-temperature-resistant nylon salt is added into double-stage double-screw extruder, pre-polymerization is carried out in the first-stage double-screw extruder, and tackifying reaction is carried out in the second-stage double-screw extruder, and the finally extruded material is high-temperature-resistant nylon copolymer.The application carries out pre-polymerization and tackifying reaction by introducing double-stage double-screw extruder, based on the good blending and shearing effect of double screw, can promote the progress of pre-polymerization and tackifying reaction, can effectively reduce production energy consumption, and production efficiency is high, process condition is easy to control, and product stability is good.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature resistant nylon, and specifically relates to a high-temperature resistant nylon copolymer and its preparation method. Background Technology

[0002] Due to the high melting point of high-temperature resistant nylon, its polymerization technology has a relatively high threshold. During polymerization, the heat transfer medium is prone to degradation, and the polymer's appearance is easily yellowed. Currently, most industrial processes employ a two-step method: first, salt prepolymerization is carried out, the prepolymer is flash-evaporated, and then the prepolymer is pulverized and added to a solid-phase thickening device for solid-phase thickening to obtain high-temperature resistant nylon. The entire process is lengthy, typically requiring more than 20 hours per batch, resulting in low production efficiency and high energy consumption.

[0003] Patent application CN101298517A discloses a polymerization method for high-temperature resistant nylon PA10T / 6T. This invention employs a two-step process: salt is formed from reactants such as diacid, diamine, and catalyst in a reactor; then, a prepolymerization reaction is carried out under high temperature and pressure; the prepolymer is sprayed out via flash evaporation and dried; finally, the dried prepolymer is melt-bonded to obtain the high-temperature resistant nylon. In this two-step method, the prepolymer processing between prepolymerization and final polymerization is complex, energy-intensive, and has low production efficiency.

[0004] Currently reported patent methods for preparing high-temperature resistant nylon generally involve a two-step process. The first step is salt prepolymerization, and the second step offers more options, typically melt thickening or solid-phase thickening. The entire process has relatively high energy consumption and low production efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-temperature resistant nylon copolymer and its preparation method. This invention introduces a two-stage twin-screw extruder into a specific reaction stage of the high-temperature resistant nylon copolymer synthesis process. By using the two-stage twin-screw extruder for the reaction, production energy consumption is effectively reduced, production efficiency is high, process conditions are easy to control, and product stability is good.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-temperature resistant nylon copolymer, the specific steps of which are as follows:

[0008] (1) Add diacid, diamine, antioxidant, end-capping agent and catalyst to polymerization reactor to carry out salt formation reaction to obtain salt solution; preferably, the temperature of salt formation reaction is 100-160℃ and the reaction time is 1-3 hours.

[0009] (2) Cool, filter and dry the salt solution produced in step (1) to obtain high-temperature resistant nylon salt;

[0010] (3) The high-temperature resistant nylon salt obtained in step (2) is added to a two-stage twin-screw extruder for reactive extrusion. The prepolymerization reaction is carried out in the first-stage twin-screw extruder, and the thickening reaction is carried out in the second-stage twin-screw extruder. The reaction extrusion time of the material is controlled at 8-12 minutes.

[0011] (4) Cool, stretch and pelletize the material extruded in step (3) to obtain high temperature resistant nylon copolymer.

[0012] In this invention, the diamine is generally an aliphatic diamine, such as butanediamine, pentanediamine, hexanediamine, nonanediamine, decanediamine, dodecanodiamine, dimethylpentanediamine, etc.; the diacid is generally an aromatic diacid, such as terephthalic acid, isophthalic acid, etc.; when multiple copolymers are used, the diacid can also be an aliphatic diacid, such as glutaric acid, adipic acid, sebacic acid, dodecanodicarboxylic acid, etc., and the molar percentage of the aliphatic diacid in the diacid is less than 30%.

[0013] In this invention, the antioxidant is one or more of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine or tris[2,4-di-tert-butylphenyl]phosphite.

[0014] In this invention, the capping agent is one or more of benzoic acid, acetic acid, propionic acid, and phthalic anhydride, more preferably benzoic acid or acetic acid.

[0015] In this invention, the catalyst is one or more of sodium phosphate, magnesium phosphate, calcium phosphate, sodium phosphite, magnesium phosphite, calcium phosphite, zinc phosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, and zinc hypophosphite, more preferably sodium phosphite or sodium hypophosphite.

[0016] In this invention, the temperature of the salt-making reaction is more preferably 120-150°C, and the reaction time is more preferably 1.5-2.5 hours.

[0017] In this invention, the length-to-diameter ratio of the first-stage and second-stage twin-screw extruders is 45-60, more preferably 50-55.

[0018] In this invention, the reaction extrusion temperature is set at 250-280℃, more preferably 260-270℃, for the first-stage twin-screw extruder, and at 300-330℃, more preferably 310-320℃, for the second-stage twin-screw extruder. The screw speed of both the first-stage and second-stage twin-screw extruders is set at 200-250 RPM.

[0019] The high-temperature resistant nylon copolymer prepared by the above preparation method has a melting point of 290-330℃, more preferably 300-320℃, and a relative viscosity of 1.9-2.4, more preferably 2.0-2.2.

[0020] Compared with the prior art, the beneficial effects of this invention are reflected in:

[0021] The method for preparing high-temperature resistant nylon copolymers provided by this invention first involves a salt-forming reaction of a diacid and a diamine to produce a dried nylon salt. Then, a twin-screw extruder is used for prepolymerization and thickening reactions. Based on the excellent blending and shearing properties of the twin screw, the prepolymerization and thickening reactions are accelerated. Compared to existing technologies that involve prepolymerization under high temperature and pressure conditions in a reactor, the method provided by this invention eliminates the need for high-pressure, solid-phase thickening, simplifying the process, reducing energy consumption, and improving production efficiency. The preparation method provided by this invention features mild reaction conditions, low energy consumption, high production efficiency, easy process control, and more stable product quality. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention. In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail.

[0023] Comparative Example 1

[0024] A method for preparing high-temperature nylon includes the following steps:

[0025] Weigh 4000g of decanediamine, 3750g of terephthalic acid, 15g of tris[2,4-di-tert-butylphenyl]phosphite, 120g of benzoic acid and 12g of sodium phosphite and add them to the polymerization reactor for salt formation reaction. The reaction temperature is 155℃ and the reaction time is 2 hours.

[0026] Continue heating to 250℃, maintaining the pressure inside the reactor at 2.6MPa, and prepolymerize for 5 hours. After the reaction is complete, spray the material into the receiving tank by flash evaporation, and then crush, cold press and granulate the prepolymer for later use.

[0027] The cold-pressed granulated prepolymer is added to a solid-phase thickening drum, and the vacuum is evacuated to below 1000 Pa. The temperature is then raised to 140°C for initial drying for 3 hours. After drying, the temperature is raised to 180°C at a rate of 20°C / h for 3 hours. The temperature is then further raised to 250°C at a rate of 10°C / h for 5 hours. Throughout the process, the vacuum is maintained below 1000 Pa. The material is cooled using circulating water, and discharged when the temperature drops below 60°C to obtain high-temperature nylon.

[0028] Comparative Example 2

[0029] A method for preparing high-temperature nylon includes the following steps:

[0030] Weigh 4000g of decanediamine, 3750g of terephthalic acid, 15g of tris[2,4-di-tert-butylphenyl]phosphite, 120g of benzoic acid and 12g of sodium phosphite and add them to the polymerization reactor for salt formation reaction. The reaction temperature is 155℃ and the reaction time is 2 hours.

[0031] Continue heating to 250℃, maintaining the pressure inside the reactor at 2.6MPa, and prepolymerize for 5 hours. After the reaction is complete, spray the material into the receiving tank by flash evaporation, and then crush and dry the prepolymer for later use.

[0032] The obtained high-temperature resistant nylon prepolymer was added to a twin-screw extruder for reactive extrusion. The length-to-diameter ratio of the twin-screw extruder was 50, the temperature of the front barrel was set at 280℃, the temperature of the rear barrel was set at 320℃, the twin-screw speed was controlled at 200RPM, and the reactive extrusion time of the material in the screw was controlled at 6 minutes.

[0033] The material extruded from the reaction is cooled, stretched, and pelletized to obtain high-temperature resistant nylon.

[0034] Example 1

[0035] A method for preparing a high-temperature resistant nylon copolymer includes the following steps:

[0036] Weigh 4000g of decanediamine, 3750g of terephthalic acid, 15g of tris[2,4-di-tert-butylphenyl]phosphite, 120g of benzoic acid and 12g of sodium phosphite and add them to the polymerization reactor for salt formation reaction. The reaction temperature is 155℃ and the reaction time is 2 hours.

[0037] The salt solution obtained from the reaction was cooled, filtered, and dried to obtain high-temperature resistant nylon salt;

[0038] The obtained high-temperature resistant nylon salt was added to a two-stage twin-screw extruder for reactive extrusion. The length-to-diameter ratio of the first and second-stage twin-screw extruders was 50. The prepolymerization reaction was carried out in the first-stage twin-screw extruder, with the screw speed controlled at 200 RPM and the temperature set at 260℃. The thickening reaction was carried out in the second-stage twin-screw extruder, with the temperature set at 320℃ and the screw speed at 200 RPM. The material was subjected to reactive extrusion for 10 minutes.

[0039] The material extruded from the reaction is cooled, stretched, and pelletized to obtain high-temperature resistant nylon.

[0040] Example 2

[0041] A method for preparing a high-temperature resistant nylon copolymer includes the following steps:

[0042] Weigh out 3390g hexamethylenediamine, 2600g terephthalic acid, 1910g adipic acid, 10g tris[2,4-di-tert-butylphenyl] phosphite, 100g benzoic acid and 8g sodium phosphite and add them to the polymerization reactor to carry out the salt formation reaction. The reaction temperature is 130℃ and the reaction time is 2 hours.

[0043] The salt solution obtained from the reaction was cooled, filtered, and dried to obtain high-temperature resistant nylon salt;

[0044] The obtained high-temperature resistant nylon salt was added to a two-stage twin-screw extruder for reactive extrusion. The length-to-diameter ratio of the first and second-stage twin-screw extruders was 55. The prepolymerization reaction was carried out in the first-stage twin-screw extruder, with the screw speed controlled at 220 RPM and the temperature set at 250℃. The thickening reaction was carried out in the second-stage twin-screw extruder, with the temperature set at 320℃ and the screw speed at 220 RPM. The reaction extrusion time was controlled at 10 minutes.

[0045] The material extruded from the reaction is cooled, stretched, and pelletized to obtain high-temperature resistant nylon.

[0046] Example 3

[0047] A method for preparing a high-temperature resistant nylon copolymer includes the following steps:

[0048] Weigh out 3718g of decanediamine, 190g of hexamethylenediamine, 3485g of terephthalic acid, 265g of m-phenylenediamine, 12g of tris[2,4-di-tert-butylphenyl]phosphite, 120g of benzoic acid and 10g of sodium phosphite and add them to the polymerization reactor for salt formation reaction. The reaction temperature is 150℃ and the reaction time is 2 hours.

[0049] The salt solution obtained from the reaction was cooled, filtered, and dried to obtain high-temperature resistant nylon salt;

[0050] The obtained high-temperature resistant nylon salt was added to a two-stage twin-screw extruder for reactive extrusion. The length-to-diameter ratio of the first and second-stage twin-screw extruders was 45. The prepolymerization reaction was carried out in the first-stage twin-screw extruder, with the screw speed controlled at 250 RPM and the temperature set at 255℃. The thickening reaction was carried out in the second-stage twin-screw extruder, with the temperature set at 325℃ and the screw speed at 250 RPM. The material was reacted and extruded for 8 minutes.

[0051] The material extruded from the reaction is cooled, stretched, and pelletized to obtain high-temperature resistant nylon.

[0052] Example 4

[0053] A method for preparing a high-temperature resistant nylon copolymer includes the following steps:

[0054] 3390g of hexamethylenediamine, 2376g of terephthalic acid, 2376g of isophthalic acid, 10g of N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, 130g of phthalic anhydride and 10g of sodium hypophosphite were weighed and added to a polymerization reactor for salt formation reaction. The reaction temperature was 120℃ and the reaction time was 1.5 hours.

[0055] The salt solution obtained from the reaction was cooled, filtered, and dried to obtain high-temperature resistant nylon salt;

[0056] The obtained high-temperature resistant nylon salt was added to a two-stage twin-screw extruder for reactive extrusion. The length-to-diameter ratio of the first and second-stage twin-screw extruders was 60. The prepolymerization reaction was carried out in the first-stage twin-screw extruder, with the screw speed controlled at 250 RPM and the temperature set at 260℃. The thickening reaction was carried out in the second-stage twin-screw extruder, with the temperature set at 325℃ and the screw speed at 250 RPM. The material was subjected to reactive extrusion for 12 minutes.

[0057] The material extruded from the reaction is cooled, stretched, and pelletized to obtain high-temperature resistant nylon.

[0058] The products prepared in the above comparative examples and embodiments were subjected to performance tests. Tensile strength, tensile modulus, flexural strength, notched impact strength of simply supported beams, and melting point were tested according to ISO 1133 and ISO 17223, respectively. The test results are shown in Table 1 below.

[0059] Table 1

[0060]

[0061] As can be seen from the test results in Table 1, the high-temperature resistant nylon produced in this application is basically consistent with the products produced by the existing methods (Comparative Example 1 and Comparative Example 2) in terms of tensile strength, flexural strength, tensile modulus, notched impact strength of simply supported beams, and appearance. However, the existing method (Comparative Example 1) has a salt-making time of 2 hours, a prepolymerization time of 5 hours, and a solid-phase thickening time of 20 hours, resulting in low production efficiency. Comparative Example 2 has a salt-making time of 2 hours and a prepolymerization time of 5 hours. At the same time, the same amount of water solvent as the product needs to be evaporated during the prepolymerization process, resulting in relatively high energy consumption.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0063] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-temperature resistant nylon copolymer, characterized in that: Includes the following steps: A diacid, a diamine, an antioxidant, a capping agent, and a catalyst are added to a polymerization reactor to carry out a salt-making reaction, resulting in a salt solution. The salt solution was cooled, filtered, and dried to obtain high-temperature resistant nylon salt. High-temperature resistant nylon salt is added to a two-stage twin-screw extruder. The prepolymerization reaction is carried out in the first-stage twin-screw extruder, and the thickening reaction is carried out in the second-stage twin-screw extruder. The final extruded material is the high-temperature resistant nylon copolymer. The total processing time of the high-temperature resistant nylon salt in the two-stage twin-screw extruder is controlled at 8-12 minutes. The salt-making reaction is carried out at a temperature of 100-160℃ for 1-3 hours. In the aforementioned two-stage twin-screw extruder, the first-stage twin-screw extruder has an aspect ratio of 45-60, a temperature of 250-280℃, and a screw speed of 200-250 RPM; the second-stage twin-screw extruder has an aspect ratio of 45-60, a temperature of 300-330℃, and a screw speed of 200-250 RPM.

2. The method for preparing the high-temperature resistant nylon copolymer according to claim 1, characterized in that: The diamine is an aliphatic diamine.

3. The method for preparing the high-temperature resistant nylon copolymer according to claim 2, characterized in that: The aliphatic diamine is at least one of butanediamine, pentadiamine, hexanediamine, nonanediamine, decanediamine, dodecanediamine, and dimethylpentanediamine.

4. The method for preparing the high-temperature resistant nylon copolymer according to claim 1, characterized in that: The dicarboxylic acid is at least one of aromatic dicarboxylic acids and aliphatic dicarboxylic acids.

5. The method for preparing the high-temperature resistant nylon copolymer according to claim 4, characterized in that: The aromatic dicarboxylic acid is at least one of terephthalic acid and isophthalic acid; the aliphatic dicarboxylic acid is at least one of glutaric acid, adipic acid, sebacic acid, and dodecanoic acid.

6. The method for preparing the high-temperature resistant nylon copolymer according to claim 4, characterized in that: The dicarboxylic acid includes aromatic dicarboxylic acids and aliphatic dicarboxylic acids, wherein the aliphatic dicarboxylic acid accounts for less than 30% of the total dicarboxylic acid.

7. The method for preparing the high-temperature resistant nylon copolymer according to claim 1, characterized in that: The antioxidant is at least one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, or tris[2,4-di-tert-butylphenyl]phosphite; the end-capping agent is at least one of benzoic acid, acetic acid, propionic acid, or phthalic anhydride; and the catalyst is at least one of sodium phosphate, magnesium phosphate, calcium phosphate, sodium phosphite, magnesium phosphite, calcium phosphite, zinc phosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, or zinc hypophosphite.

8. A high-temperature resistant nylon copolymer, characterized in that: The high-temperature resistant nylon copolymer is prepared by the preparation method according to any one of claims 1 to 7.

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