CN112029090A

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Info

Publication number: CN112029090A
Application number: CN201910474696.4A
Authority: CN
Inventors: 邵威; 郑毅; 张强; 赵元博; 刘修才
Original assignee: Cathay R&D Center Co Ltd; CIBT America Inc
Current assignee: Cathay R&D Center Co Ltd; Cathay Biotech Inc; CIBT America Inc
Priority date: 2019-06-03
Filing date: 2019-06-03
Publication date: 2020-12-04

Abstract

The invention discloses a high-temperature-resistant low-water-absorption polyamide copolymer PA5XT and a preparation method thereof. The polyamide copolymer PA5XT comprises the following structural units:

and/or

Description

High-temperature-resistant low-water-absorption polyamide copolymer 5XT and preparation method thereof

Technical Field

The invention belongs to the field of high polymer materials, and particularly relates to a high-temperature-resistant low-water-absorption polyamide copolymer PA5XT and a preparation method thereof.

Background

Polyamides are widely used for automobile parts, parts of electric and electronic equipment, and many other applications because of their excellent mechanical properties and moldability. However, the main component of polyamide nylon is polyamide, which contains amino and carbonyl groups and is easy to form hydrogen bonds with water molecules, so that various obtained materials are easy to absorb water during use, and generate a plasticizing effect, so that the volume expansion and modulus of the materials are reduced, obvious creep deformation occurs under the action of stress, and the dimensional stability is greatly reduced.

The polyamide PA6 and the polyamide PA66 are the most commonly used polyamide materials, can absorb 10 percent of moisture from humid air at the highest, and can absorb 2 to 4 percent of moisture in mass fraction under a general humidity environment, so that various mechanical property changes and dimensional deformation are caused. Therefore, it is necessary to reduce the water absorption of polyamide.

Meanwhile, the polyamide is popularized and applied in various fields due to the characteristics of stable performance, weather resistance, corrosion resistance and the like, but the polyamide needs to be further improved in heat resistance in special use environments such as the field of automobile engines.

The pentanediamine is polyamide PA56 synthesized by the monomer and a copolymer, and has excellent service performance like polyamide PA66, wherein the pentanediamine is the monomer prepared by the national proprietary intellectual property bio-based method.

In the prior art, no relevant report is provided for a polyamide copolymer PA5XT which is prepared by taking pentanediamine, long carbon chain dibasic acid and terephthalic acid as raw materials and has high temperature resistance and low water absorption performance.

Disclosure of Invention

In order to solve the defects of the prior art and products, the invention provides a polyamide copolymer PA5XT, a preparation method and application thereof.

The invention provides a polyamide copolymer PA5XT, wherein the polyamide copolymer PA5XT comprises the following structural units:

wherein x is an integer of 6 to 18, and y is an integer of 2 to 16; preferably, x is an integer of 8 to 18 and y is an integer of 4 to 8, and more preferably, x is an integer of 11 to 18 and y is an integer of 4 to 6.

The inventors have found that a suitable range of the molar ratio of the structural units (I) and (II) has a significant influence on the physico-chemical properties of the polyamide copolymer PA5 XT. In a preferred embodiment of the invention, the molar ratio of the structural units (I) and (II) in the polyesteramide is 10 to 50: 20 to 90, more preferably 10 to 50: 50-90, more preferably 15-50: 50-85.

In some preferred embodiments of the present invention, the starting material for the polyamide copolymer PA5XT comprises the following monomers:

100 parts of pentamethylene diamine, namely 100 parts of pentamethylene diamine,

5-65 parts of long-carbon-chain dibasic acid, and more preferably 10-50 parts;

5-90 parts of terephthalic acid and/or derivatives thereof, and more preferably 20-90 parts;

wherein all parts are calculated on the basis of the amount of the substance.

In some preferred embodiments of the present invention, the pentanediamine may be chemically or biologically derived, preferably biologically derived 1, 5-pentanediamine; and/or the presence of a gas in the gas,

the long carbon chain dibasic acid is selected from one or more of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid, and is preferably dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid or octadecanedioic acid; and/or the presence of a gas in the gas,

the terephthalic acid derivative is one selected from terephthalic acid chloride, dimethyl terephthalate and diethyl terephthalate.

In some preferred embodiments of the present invention, the polyamide copolymer PA5XT further comprises 0.001 to 0.3 part, more preferably 0.01 to 0.3 part, of a heat stabilizer, wherein the parts are mole parts,

the heat stabilizer is one or more selected from phosphoric acid, phosphorous acid, trimethyl phosphite, triphenyl phosphite, trimethyl phosphate, triphenyl phosphate, sodium hypophosphite, zinc hypophosphite, calcium hypophosphite and potassium hypophosphite.

In some preferred embodiments of the invention, the sum of the moles of the long carbon chain diacid and the moles of terephthalic acid and/or its derivatives, and the ratio of the moles of pentanediamine, is (1-1.05): 1.

in some preferred embodiments of the present invention, the mole fraction of the pentanediamine, the long carbon chain dibasic acid and the terephthalic acid and/or the derivative thereof is 100: (10-50): (20-90), more preferably 100: (10-50): (50-90), more preferably 100: (15-50): (50-85).

In some preferred embodiments of the present invention, the polyamide copolymer PA5XT has a relative viscosity of 1.0 to 3.2.

In some preferred embodiments of the invention, the ratio according to ISO-62: according to a 2008 standard test, the water absorption rate of the polyamide copolymer PA5XT is 4.0-12.1%, preferably 4.5-10%, and more preferably 5-7%.

The polyamide copolymer PA5XT has a tensile strength of 50 to 140MPa, and more preferably 60 to 120 MPa.

In some preferred embodiments of the present invention, the flexural strength of the polyamide copolymer PA5XT is 67 to 120MPa, and more preferably 79 to 120 MPa.

In some preferred embodiments of the present invention, the polyamide copolymer PA5XT has a heat distortion temperature of 140 to 260 ℃, more preferably 200 to 245 ℃.

The inventor finds out through a great deal of research that: the polyamide copolymer PA5XT utilizes rigid benzene rings contained in terephthalic acid residues to improve the heat resistance and mechanical properties of PA5 XT. Meanwhile, the steric effect generated by the benzene ring can effectively reduce the damage of water molecules to hydrogen bonds among polyamide molecules under the humidity condition, thereby reducing the combination of the water molecules and carbonyl and amino in the polyamide, namely reducing the water absorption rate and simultaneously keeping better dimensional stability. The polyamide copolymer PA5XT maintains the excellent use performance of polyamide, and simultaneously further improves the heat resistance and mechanical property. Meanwhile, a flexible alkane chain segment is introduced into the polyamide copolymer PA5XT by adopting the residue of the long carbon chain dibasic acid, so that the impact resistance of the polymer is favorably improved, the density of the amide group which is easy to absorb water in the polymer structure is reduced, and the water absorption is further reduced.

In another aspect of the present invention, a method for preparing the high temperature resistant and low water absorption polyamide copolymer PA5XT is provided, the method comprising the following steps:

1) adding pentanediamine, long carbon chain dibasic acid, terephthalic acid and/or derivatives thereof into water under an inert gas atmosphere to prepare a solution of nylon salt PA5 XT;

2) heating a solution of nylon salt PA5XT to increase the pressure in a reaction system to 0.3-3.2 Mpa, exhausting and maintaining the pressure, wherein the temperature of the reaction system is 232-270 ℃ when the pressure maintaining is finished, then reducing the pressure to reduce the pressure in the reaction system to 0-0.2 Mpa (gauge pressure), and the temperature of the reaction system is 230-300 ℃ after the pressure reduction is finished; vacuumizing to ensure that the vacuum degree is between-0.02 MPa and-0.1 MPa, and vacuumizing for 20-60 min to obtain a melt;

3) and (3) carrying out bracing and dicing on the melt to obtain the high-temperature-resistant low-water-absorption polyamide PA5XT copolymer.

In some preferred embodiments of the present invention, in step 1), the pentamethylene diamine is chemically or biologically derived, preferably biologically derived 1, 5-pentamethylene diamine; and/or the presence of a gas in the gas,

In some preferred embodiments of the present invention, in step 1), the sum of the moles of the long carbon chain dibasic acid and terephthalic acid and/or derivative thereof, and the ratio of the moles of pentanediamine, is (1-1.05): 1.

in some preferred embodiments of the present invention, in step 1), the mole fraction of the pentanediamine, the long carbon chain dibasic acid and the terephthalic acid and/or the derivative thereof is preferably 100: (10-50): (20-90), more preferably 100: (10-50): (50-90).

In some preferred embodiments of the present invention, in step 1), the raw material of the polyamide copolymer PA5XT further includes 0.001 to 0.3 part, more preferably 0.01 to 0.3 part, of a heat stabilizer, where the parts are mole parts;

Preferably, in step 2), the heat stabilizer is added before the salt solution is heated.

In a preferred embodiment, in the step 1), the concentration of the solution of the nylon salt PA5XT is between 40 and 75%, and the percentage is the mass percentage of the solution of the nylon salt PA5 XT.

In a preferred embodiment, in step 1), the pH value of the solution of nylon salt PA5XT at a concentration of 10% is 6 or more, preferably 7.0 to 8.2, and the percentage is a mass percentage of the solution of nylon salt PA5 XT.

In a preferred embodiment, in step 1), the inert gas includes one or more of nitrogen, argon or helium.

In a preferred embodiment, in the step 2), the heating time is within 1-2 h; and/or the presence of a gas in the gas,

the pressure for pressure maintaining is 0.3-3.2 MPa, and in the invention, as the polyamide copolymer PA5XT with better mechanical property, dimensional stability and lower water absorption rate is obtained, compared with the low pressure maintaining process (0.3-1.6 MPa) of common polymerization, the high pressure maintaining process (1.8-3.2 MPa) contains more water in a polymerization reaction system and has a certain slow polymerization effect, and the heat transfer of the system is more sufficient due to the presence of the water, so that the polymerization is more uniform, the mechanical property and the water absorption property of the polyamide copolymer PA5XT are improved, and the pressure for pressure maintaining is further preferably 1.6-3.2 MPa; and/or the presence of a gas in the gas,

the pressure maintaining time is 2-5 h; and/or the presence of a gas in the gas,

the pressure reduction time is 40 min-2 h.

In a preferred embodiment, in step 3), the relative viscosity of the polyamide copolymer PA5XT is 1.0 to 3.2.

In another aspect of the present invention, there is provided a molded article prepared from the above polyamide copolymer PA5XT as a raw material.

In order to obtain the molded article of the present invention, the polyamide copolymer PA5XT of the present invention can be molded by any molding method such as injection molding, extrusion molding, blow molding, vacuum molding, melt spinning, and film molding. These molded articles can be molded into a desired shape and used for resin molded articles such as automobile parts and machine parts. Compared with the prior art, the implementation of the invention has at least the following advantages:

1. the polyamide copolymer PA5XT synthesized by the invention has the same comprehensive use performance as polyamide, and uses the monomer pentamethylene diamine developed by domestic independent intellectual property rights, thereby avoiding the use of foreign monopoly monomer hexamethylene diamine.

2. The polyamide copolymer PA5XT synthesized by the invention has excellent mechanical properties, and the tensile property, the bending resistance and the impact resistance of the polyamide copolymer PA5XT are all inferior to polyamide products such as polyamide PA6, polyamide PA66 and the like used in the market.

3. The polyamide copolymer PA5XT synthesized by the method has lower water absorption, better dimensional stability and higher thermal deformation temperature than polyamide PA6 and polyamide PA66, can be used in a more severe use environment, and expands the use range of polyamide to a certain extent.

4. The preparation method of the polyamide copolymer PA5XT is simple, the process parameters are easy to control, large instruments are not needed for assistance, and the quantitative production is convenient to carry out.

5. The polyamide copolymer PA5XT enriches the variety of polyamide copolymers and is a product with a novel structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Method for detecting relative viscosity eta r

Concentrated sulfuric acid method with Ubbelohde viscometer: the dried polyamide sample was weighed accurately at 0.5. + -. 0.0002g, dissolved by adding 50mL of concentrated sulfuric acid (98%), and the concentrated sulfuric acid flow time t0 and the polyamide solution flow time t were measured and recorded in a thermostatic water bath at 25 ℃.

Relative viscosity calculation formula:

relative viscosity eta r t/t0

Wherein: t: the time of solution flow; t 0: the solvent was run through time.

Mechanical property testing method

Bending test reference standard ISO-178, test conditions: 2 mm/min;

tensile test reference standard ISO-572-2, test conditions: 50 mm/min;

water absorption test: ISO-62: 2008;

dimensional stability (shrinkage) test: ISO-2577-2007;

testing the heat distortion temperature: ASTM D648;

the impact test is a cantilever beam notch impact reference test standard ISO-180/1A, and the test conditions are as follows: at 23 ℃.

1, 5-Pentanediamine, Tridecanedioic acid, tetradecanedioic acid were purchased from Kaiser (Jinxiang) biomaterials Co., Ltd., terephthalic acid was purchased from Guinea (Shanghai) industries Co., Ltd., and adipic acid was purchased from Chemicals, Inc., of the national drug group. Other starting materials, reagents are either prepared by methods well known in the literature or are commercially available.

Example 1

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 2mol of tridecanedioic acid (DC13), 8mol of terephthalic acid (PTA) and water, wherein the molar ratio of the 1, 5-pentanediamine to the terephthalic acid to the DC13 is 1:0.8:0.2, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

And adding a heat stabilizer sodium hypophosphite into the 60 wt.% nylon salt solution, wherein the addition amount of the heat stabilizer sodium hypophosphite is 0.002mol and 0.02%, and the percentage is the percentage accounting for the molar weight of the total acid.

(2) Heating the solution, increasing the pressure in the reaction system to 2.40Mpa, maintaining the pressure at 2.40Mpa for 1 hr and 30min, maintaining the temperature at 243 deg.C for 3 hr, reducing the pressure to 0.005Mpa (gauge pressure), and increasing the temperature at 290 deg.C for 1 hr.

(3) Vacuumizing at-0.08 MPa for 30min at 290 deg.C to obtain polyamide copolymer melt.

(4) And (4) melting, discharging, bracing and dicing to obtain the polyamide copolymer.

The relative viscosity test of the obtained polyamide copolymer PA513T gave a result of 2.71. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Example 2

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 4mol of tridecanedioic acid (DC13), 6mol of terephthalic acid (PTA) and water, wherein the molar ratio of the 1, 5-pentanediamine to the terephthalic acid to the tridecanedioic acid is 1:0.6:0.4, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

(2) Heating the solution, increasing the pressure in the reaction system to 2.40Mpa, maintaining the pressure at 2.40Mpa for 1 hr and 30min, maintaining the temperature at 245 deg.C for 3 hr, reducing the pressure to 0.005Mpa (gauge pressure), and increasing the temperature at 290 deg.C for 1 hr.

The relative viscosity test of the obtained polyamide copolymer PA513T gave a result of 2.73. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Example 3

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 5mol of tridecanedioic acid (DC13), 5mol of terephthalic acid (PTA) and water, wherein the molar ratio of the 1, 5-pentanediamine to the terephthalic acid to the tridecanedioic acid is 1:0.5:0.5, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

The polyamide copolymer PA513T obtained was subjected to a relative viscosity test and found to be 2.70. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Example 4

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 6mol of tridecanedioic acid (DC13), 4mol of terephthalic acid (PTA) and water, wherein the molar ratio of the 1, 5-pentanediamine, the terephthalic acid and the tridecanedioic acid is 1:0.4:0.6, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.99.

The relative viscosity test of the resulting polyamide copolymer PA513T gave a result of 2.72. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Example 5

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 4mol of tridecanedioic acid (DC13), 6mol of terephthalic acid (PTA) and water, wherein the molar ratio of the 1, 5-pentanediamine to the terephthalic acid to the tridecanedioic acid is 1:0.6:0.4, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.99.

And adding a heat stabilizer phosphorous acid into the 60 wt.% nylon salt solution, wherein the adding amount of the heat stabilizer phosphorous acid is 0.002mol and 0.02%, and the percentage is the percentage of the total acid in molar weight.

(4) The melt was discharged, drawn into strands and pelletized, to obtain a polyamide copolymer which was slightly yellow in color as compared with the polyamide copolymer obtained in example 2.

Example 6

(2) Heating the solution, increasing the pressure in the reaction system to 1.60Mpa, taking 1 hour and 30 minutes, exhausting, maintaining the pressure at 1.60Mpa, keeping the temperature of the reaction system at 245 ℃ when the pressure maintaining is finished, reducing the pressure to 0.005Mpa (gauge pressure) when the pressure maintaining is taken for 3 hours, reducing the temperature of the reaction system at 290 ℃ when the pressure reducing is finished, and taking 1 hour for pressure reducing.

The polyamide copolymer PA513T obtained was subjected to a relative viscosity test and found to be 2.74. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Example 7

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 4mol of tetradecanedioic acid (DC14) and 6mol of terephthalic acid (PTA) with water, wherein the molar ratio of the 1, 5-pentanediamine to the terephthalic acid to the tetradecanedioic acid is 1:0.6:0.4, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.99.

(3) Vacuumizing at-0.08 MPa for 30min at 310 deg.C to obtain polyamide copolymer melt.

The polyamide copolymer PA5XT obtained was subjected to a relative viscosity test and found to be 2.62. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Comparative example 1

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 10mol of adipic acid (DC6) and water, wherein the molar ratio of the 1, 5-pentanediamine to the adipic acid is 1:1, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

(2) Heating the solution, increasing the pressure in the reaction system to 2.40Mpa, maintaining the pressure at 2.40Mpa for 1 hr and 30min, reducing the pressure to 0.005Mpa (gauge pressure) after 3 hr, and decreasing the temperature to 275 deg.C for 1 hr.

(4) And (4) melting, discharging, drawing into strips and cutting into granules to obtain the polyamide PA56 resin.

The relative viscosity test of the obtained polyamide PA56 resin showed 2.70. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Comparative example 2

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 10mol of tridecane dibasic acid (DC13) and water, wherein the molar ratio of the 1, 5-pentanediamine to the DC13 is 1:1, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at 10 wt.% nylon salt solution concentration was 8.20.

(4) And melting, discharging, drawing strips and cutting into granules to obtain the polyamide PA513 resin.

The relative viscosity of the obtained polyamide PA513 resin was measured and found to be 2.74. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Comparative example 3

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 6-hexamethylene diamine (6N), 10mol of adipic acid (DC6) and water, wherein the molar ratio of the 1, 6-hexamethylene diamine to the adipic acid is 1:1, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

(4) And (4) melting, discharging, drawing into strips and cutting into granules to obtain the polyamide PA66 resin.

The relative viscosity test of the obtained polyamide PA66 resin showed 2.70. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

Comparative example 4

(1) Under the condition of nitrogen, uniformly mixing 10mol of 1, 5-pentanediamine, 4mol of adipic acid and 6mol of terephthalic acid (PTA) with water, wherein the molar ratio of the 1, 5-pentanediamine to the adipic acid is 1:0.6:0.4, and preparing 60 wt.% of nylon salt solution, wherein the percentage is the mass percentage of the nylon salt solution; the pH at a nylon salt solution concentration of 10 wt.% was 7.98.

And adding 0.002mol, 0.02% of thermal stabilizer sodium hypophosphite into the 60 wt.% nylon salt solution, wherein the percentage is the percentage of the total acid molar weight.

(2) Heating the solution, increasing the pressure in the reaction system to 2.40Mpa, taking 1 hour and 30 minutes, exhausting, maintaining the pressure, reducing the pressure in the reaction system to 0.005Mpa (gauge pressure) after the pressure maintaining is finished and 3 hours after the pressure maintaining is used, and taking 1 hour after the pressure reducing is finished and the temperature of the reaction system is 290 ℃;

(4) Melting, discharging, bracing and dicing to obtain polyamide copolymerized polyamide resin;

the obtained PA56T copolymer resin was subjected to a relative viscosity test, and the result was 2.71. Reference is then made to standard ISO-178, standard ISO-572-2, standard ISO-62: 2008. ISO-2577-2007 and ASTM D648 test the thermal performance and water absorption of the prepared transparent polyamide; the test results show that the tensile strength, flexural strength, water absorption, heat distortion temperature and measurement results of the resin are shown in Table 1.

TABLE 1

As can be seen from Table 1:

1. by comparing examples 1-4 with comparative examples 1 and 2, the addition of terephthalic acid caused a significant increase in the heat distortion temperature, tensile strength, and flexural strength of polyamide copolymer PA5 XT. The rigid benzene ring in the terephthalic acid segment is favorable for improving the rigidity and the heat resistance of a polymer chain, so that the thermodynamic property of the polyamide copolymer PA5XT is obviously improved, the restriction of the performance of the polyamide copolymer PA5X is overcome, and the polyamide copolymer with excellent comprehensive performance is obtained.

2. As can be seen by comparing examples 1-4 with comparative examples 1-3, the polyamide copolymer PA5XT in the examples of the invention has excellent comprehensive performance, higher tensile strength, bending strength, impact strength, lower water absorption and dimensional stability compared with polyamide PA513, polyamide PA66 and polyamide PA 56. Compared with the polyamide copolymer PA56T with the medium-long carbon chain segment, the polyamide copolymer PA5XT with the long carbon chain segment has the advantages of low water absorption, good dimensional stability, high impact strength and the like, and has very excellent performance advantages in a certain application field.

In conclusion, the polyamide copolymer PA5XT synthesized by the invention has a novel structural composition and performance superior to that of polyamide synthesized by conventional monomers, and can be used in resin molded products of automobile parts, mechanical parts and the like.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Polyamide copolymer PA5XT, characterized in that the polyamide copolymer PA5XT comprises the following structural units:

and/or

2. Polyamide copolymer PA5XT, characterized in that the polyamide copolymer PA5XT is prepared from the following monomers:

5-65 parts of long-carbon-chain dibasic acid, and more preferably 10-50 parts;

wherein all parts are by weight of the material;

the long carbon chain dibasic acid is selected from one or more of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid, and is preferably dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid or octadecanedioic acid.

3. Polyamide copolymer PA5XT according to claim 2, characterized in that the pentanediamine is of chemical or biological origin, preferably 1, 5-pentanediamine of biological origin; and/or the presence of a gas in the gas,

the terephthalic acid derivative is one of terephthalic acid chloride, dimethyl terephthalate and diethyl terephthalate; and/or the presence of a gas in the gas,

the sum of the mole numbers of the long carbon chain dibasic acid and the terephthalic acid and/or the derivative thereof and the mole number ratio of the pentanediamine are (1-1.05): 1; and/or the presence of a gas in the gas,

the mole fraction of the pentanediamine, the long carbon chain dibasic acid and the terephthalic acid and/or the derivative thereof is preferably 100: (10-50): (20-90), more preferably 100: (10-50): (50-90).

4. The polyamide copolymer PA5XT of claim 2, wherein the polyamide copolymer PA5XT further comprises 0.001-0.3 part, preferably 0.01-0.3 part, of a heat stabilizer, the parts being mole parts,

5. The polyamide copolymer PA5XT of claim 2, wherein the polyamide copolymer PA5XT has a relative viscosity of 1.0 to 3.2; and/or the presence of a gas in the gas,

according to ISO-62: according to a 2008 standard test, the water absorption rate of the polyamide copolymer PA5XT is 4.0-12.1%, preferably 4.5-10%, and more preferably 5-7%; and/or the presence of a gas in the gas,

the polyamide copolymer PA5XT has a tensile strength of 50-140 MPa, and more preferably 60-120 MPa; and/or the presence of a gas in the gas,

the bending strength of the polyamide copolymer PA5XT is 67-120 MPa, and preferably 79-120 MPa; and/or the presence of a gas in the gas,

the polyamide copolymer PA5XT has a heat distortion temperature of 140-260 ℃, and more preferably 200-245 ℃.

6. A process for preparing the polyamide copolymer PA5XT as claimed in any one of claims 1 to 5, characterized in that it comprises the following steps:

1) under the inert gas atmosphere, adding pentanediamine, long carbon chain dibasic acid, terephthalic acid and/or derivatives thereof into water to prepare a solution of nylon salt PA5 XT;

3) carrying out bracing and dicing on the melt to obtain the high-temperature-resistant low-water-absorption polyamide PA5XT copolymer;

wherein, the long carbon chain dibasic acid is selected from one or more of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid, and is preferably dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid or octadecanedioic acid.

7. The process according to claim 6, characterized in that in step 1), the pentanediamine is of chemical or biological origin, preferably 1, 5-pentanediamine of biological origin; and/or the presence of a gas in the gas,

8. The method of claim 6, wherein, in step 1),

the mole fraction of the pentanediamine, the long carbon chain dibasic acid and the terephthalic acid and/or the derivative thereof is preferably 100: (10-50): (20-90), more preferably 100: (10-50): (50-90); and/or the presence of a gas in the gas,

the polyamide copolymer PA5XT also comprises 0.001-0.3 part of heat stabilizer, more preferably 0.01-0.3 part, wherein the parts are mole parts;

9. The method of claim 6, wherein, in step 2),

adding the heat stabilizer before heating the salt solution; and/or the presence of a gas in the gas,

the pressure for maintaining the pressure is 0.3-3.2 Mpa, and the preferable pressure is 1.6-3.2 Mpa; and/or the presence of a gas in the gas,

and the pressure maintaining time is 2-5 h.

10. A molded article, which is molded by one or more molding methods selected from the group consisting of injection molding, extrusion molding, blow molding, vacuum molding, melt spinning and film molding, using the polyamide copolymer PA5XT according to any one of claims 1 to 5.