阅读说明：本技术 超高韧性支化聚酰胺共聚物的制备方法、制得的聚酰胺共聚物 (Preparation method of ultrahigh-toughness branched polyamide copolymer and prepared polyamide copolymer ) 是由 汪钟凯 刘伟 丁永良 周喜 王钟 于 2021-08-23 设计创作，主要内容包括：本发明公开超高韧性支化聚酰胺共聚物的制备方法,涉及聚酰胺技术领域,包括以下步骤：(1)用溶剂A溶解直链二元酸获得直链二元酸溶液,用溶剂B溶解二元胺B获得二元胺溶液B,用溶剂C溶解二元胺C获得二元胺溶液C；(2)将二元胺溶液B滴加至直链二元酸溶液中获得酰胺盐溶液B；将二元胺溶液C滴加至直链二元酸溶液中,收集沉淀为酰胺盐C；(3)将酰胺盐溶液B与酰胺盐C混合,加入催化剂,熔融缩聚。本发明还提供采用上述方法制得的产物。本发明的优点：不同侧链二元胺的比例影响聚酰胺共聚物的网络结构,能够调节聚酰胺共聚物的性能。制得的支化共聚物力学性能优良,适合熔融共混增韧、熔融挤出纺丝、吹塑薄膜及热熔胶等领域。(The invention discloses a preparation method of a branched polyamide copolymer with ultrahigh toughness, which relates to the technical field of polyamide and comprises the following steps: (1) dissolving linear chain dibasic acid by using a solvent A to obtain a linear chain dibasic acid solution, dissolving diamine B by using a solvent B to obtain a diamine solution B, and dissolving diamine C by using a solvent C to obtain a diamine solution C; (2) dropwise adding the diamine solution B into the linear chain diacid solution to obtain an amide salt solution B; dropwise adding the diamine solution C into the linear-chain diacid solution, and collecting the precipitate to obtain amide salt C; (3) and mixing the amide salt solution B with the amide salt C, adding a catalyst, and carrying out melt polycondensation. The invention also provides a product prepared by the method. The invention has the advantages that: the proportion of different side chain diamines influences the network structure of the polyamide copolymer, and the performance of the polyamide copolymer can be adjusted. The prepared branched copolymer has excellent mechanical property, and is suitable for the fields of melt blending toughening, melt extrusion spinning, blown film, hot melt adhesive and the like.)

1. A method for preparing a branched polyamide copolymer with ultrahigh toughness is characterized in that: the method comprises the following steps:

(1) dissolving linear chain dibasic acid by using a solvent A to obtain a linear chain dibasic acid solution, dissolving diamine B by using a solvent B to obtain a diamine solution B, and dissolving diamine C by using a solvent C to obtain a diamine solution C;

the diamine B comprises linear diamine or linear diamine and diamine with non-reacted side groups, and the diamine C comprises diamine with reacted side groups;

(2) dropwise adding the diamine solution B into the linear chain diacid solution, and mixing to obtain an amide salt solution B; dropwise adding the diamine solution C into the linear chain diacid solution, mixing, and collecting the precipitate to obtain an amide salt C;

(3) and adding the amide salt solution B and the amide salt C into a reaction kettle, adding a catalyst, and carrying out melt polycondensation to obtain the ultrahigh-toughness branched polyamide copolymer.

2. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: and (3) adjusting the pH value of the amide salt solution B to 6.5-7.5 in the step (2), and then heating and evaporating the solvent to concentrate the amide salt solution with the solute mass fraction of 60-80%.

3. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: and (3) adjusting the pH value of the amide salt solution C to 6.5-7.5 in the step (2), collecting the precipitate, and drying to obtain the amide salt C.

4. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the molar ratio of the linear chain dibasic acid to the diamine B in the solution obtained in the step (2) is 0.98:1-1.02:1, and the molar ratio of the linear chain dibasic acid to the diamine C in the solution obtained in the step (3) is 0.98:1-1.02: 1.

5. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the mass fraction of the amide salt solution B is 89-97%, the mass fraction of the amide salt C is 2-10%, and the mass fraction of the catalyst is 1-2%.

6. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the melt polycondensation in the step (3) comprises the following steps: heating to 100-170 ℃ for 1-2h, heating to 150-170 ℃ for 2-3h for prepolymerization, removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity, heating to 200-280 ℃ for removing water generated by the reaction through vacuumizing, reaching the expected viscosity after 4-8h, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain the ultrahigh-toughness branched polyamide copolymer.

7. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the straight-chain dibasic acid is malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid or tetradecanedioic acid.

8. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the diamine with the side group which does not react is dimethyl pentanediamine, 1, 2-propane diamine, 1, 3-diaminopentane, 2-dimethyl-1, 3-propane diamine, 2, 4-diaminophenol or 4-fluoro-1, 3-diaminobenzene.

9. The process for the preparation of the ultra-high toughness branched polyamide copolymer of claim 1, wherein: the linear chain diamine is ethylenediamine, 1, 3-propanediamine, 1, 4-diaminobutane, 1, 5-pentanediamine, 1, 6-hexanediamine, 2, 4-trimethyl-1, 6-hexanediamine, 2,4, 4-trimethyl-1, 6-hexanediamine, cis-1, 4-cyclohexanediamine, trans-1, 4-cyclohexanediamine, 1, 8-octanediamine, 1, 9-nonanediamine, 1, 10-decanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, cyclohexanediamine, methylcyclohexanediamine, p-phenylenediamine, m-phenylenediamine or dimethyldiamine.

10. An ultra-high toughness branched polyamide copolymer produced by the process of any one of claims 1-9.

Technical Field

The invention relates to the technical field of polyamide, in particular to a preparation method of a branched polyamide copolymer with ultrahigh toughness and a prepared polyamide copolymer.

Background

Nylon is commonly known as Polyamide (polyamine), abbreviated as PA, and is a general name of thermoplastic resins containing recurring amide groups- [ NHCO ] -in the main chain of the molecule, including aliphatic PA, semi-aromatic PA and aromatic PA. Polyamides are generally obtained by three methods, namely amino acid polycondensation, lactam ring-opening polymerization and dicarboxylic acid and diamine polycondensation. Polyamide is one of five engineering plastics, has huge yield and is applied to various industries to become an indispensable structural material. The main performance characteristics are as follows: (1) the mechanical property is excellent, the mechanical strength is high, and the toughness is good; (2) the self-lubricating property is good, the friction resistance is good, and the friction coefficient is small; (3) the heat resistance is excellent, the heat distortion temperature is high, and the product can be used at high temperature for a long time; (4) the electric insulating property is excellent, and the material is an excellent electric material; (5) the weather resistance is excellent; (6) nylon has a high water absorption due to the amide bond.

In various fields of automobiles, electric, electronics, energy sources and the like in life, the application of polyamide is very wide, but the polyamide sold in the market at present has large quantity of PA6 and PA66 with general mechanical property and high water absorption, and long-chain polyamide such as PA11, PA12, PA9T, PA10T and other special polyamides are used in the fields of aerospace and military industry. But the performance is single, the copolymerization is difficult to realize, and the polyamide copolymer with adjustable performance is difficult to obtain by a simple method at lower cost.

Patent publication No. CN1497005A discloses a polyamide and a resin composition, in which polyamide is synthesized using dimethylpentanediamine and azelaic acid as partial raw materials, and ferroelectric properties, solubility, and insulating properties thereof are studied, but mechanical properties thereof are not studied.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for preparing a polyamide copolymer with ultrahigh toughness, which can adjust the mechanical property of the polyamide copolymer by adjusting the content of amide salt generated in an esterification reaction.

The invention solves the technical problems through the following technical means:

a method for preparing an ultra-high tenacity branched polyamide copolymer comprising the steps of:

(1) dissolving linear chain dibasic acid by using a solvent A to obtain a linear chain dibasic acid solution, dissolving diamine B by using a solvent B to obtain a diamine solution B, and dissolving diamine C by using a solvent C to obtain a diamine solution C;

the diamine B comprises linear diamine or linear diamine and diamine with non-reacted side groups, and the diamine C comprises diamine with reacted side groups;

(2) dropwise adding the diamine solution B into the linear chain diacid solution, and mixing to obtain an amide salt solution B; dropwise adding the diamine solution C into the linear chain diacid solution, mixing, and collecting the precipitate to obtain an amide salt C;

(3) and adding the amide salt solution B and the amide salt C into a reaction kettle, adding a catalyst, and carrying out melt polycondensation to obtain the ultrahigh-toughness branched polyamide copolymer.

Has the advantages that: the invention can regulate and control the network structure of the polyamide copolymer by regulating the amount of diamine with side groups which react to obtain the branched polyamide copolymer with different performances, and the prepared polyamide copolymer has excellent mechanical property and tensile fracture toughness of 295.7MJ/M³The water absorption is low, the melting point is between 120-170 ℃, the degradation temperature is more than 350 ℃, and the catalyst has wider additionThe temperature of the working window is suitable for the application fields of melt blending toughening, melt extrusion spinning, blown film, hot melt adhesive and the like.

Meanwhile, the amide salt prepared by using the diamine without the side group is in a liquid state, can be well and uniformly mixed with the amide salt in a solid state to obtain a uniform amide salt solution, and the liquid amide salt has the advantages of high heat transfer rate and uniform heat transfer, and is not easy to cause the problem of nonuniform material reaction degree caused by local overheating frequently generated in melt polymerization.

Preferably, the pH value of the amide salt solution B is adjusted to 6.5-7.5 in the step (2), and then the amide salt solution with the solute mass fraction of 60-80% is concentrated by heating and evaporating the solvent.

Has the advantages that: the pH value is adjusted to keep the solution neutral, and the phenomenon that the polymer is blocked due to the excessive amount of the dibasic acid or the diamine is avoided.

Preferably, the pH value is 6.8-7.4.

Preferably, the pH value of the amide salt solution C is adjusted to 6.5-7.5 in the step (2), and then the precipitate is collected and dried to obtain the amide salt C.

Has the advantages that: the pH value is adjusted to keep the solution neutral, and the phenomenon that the polymer is blocked due to the excessive amount of the dibasic acid or the diamine is avoided.

Preferably, the pH value is 6.8-7.4.

Preferably, the molar ratio of the linear dibasic acid to the diamine B in the solution of the step (2) is 0.98:1-1.02:1, and the molar ratio of the linear dibasic acid to the diamine C in the solution of the step (3) is 0.98:1-1.02: 1.

Preferably, the diamine accounts for 35-40% of the total mass of the diamine and the linear diacid; the dibasic acid accounts for 60-65% of the total mass of the diamine and the straight chain dibasic acid.

Preferably, in the step (3), the mass fraction of the amide salt solution B is 89-97%, the mass fraction of the amide salt C is 2-10%, and the mass fraction of the catalyst is 1-2%.

Preferably, the melt polycondensation in the step (3) comprises the steps of: heating to 100-170 ℃ for 1-2h, heating to 150-170 ℃ for 2-3h for prepolymerization, removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity, heating to 200-280 ℃ for removing water generated by the reaction through vacuumizing, reaching the expected viscosity after 4-8h, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain the ultrahigh-toughness branched polyamide copolymer.

Preferably, the linear dibasic acid is malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid or tetradecanedioic acid.

Preferably, the diamine having pendant unreacted groups is 2-methylpentanediamine, 1, 2-propanediamine, 1, 3-diaminopentane, 2-dimethyl-1, 3-propanediamine, 2, 4-diaminophenol or 4-fluoro-1, 3-diaminobenzene.

Preferably, the linear diamine is ethylenediamine, 1, 3-propylenediamine, 1, 4-diaminobutane, 1, 5-pentylenediamine, 1, 6-hexylenediamine, 2, 4-trimethyl-1, 6-hexylenediamine, 2,4, 4-trimethyl-1, 6-hexylenediamine, cis-1, 4-cyclohexyldiamine, trans-1, 4-cyclohexyldiamine, 1, 8-octylenediamine, 1, 9-nonyldiamine, 1, 10-decyldiamine, dodecyldiamine, tridecanediamine, tetradecanediamine, cyclohexyldiamine, methylcyclohexanediamine, p-phenylenediamine, m-phenylenediamine or dimethyldiamine.

Preferably, the diamine with the side group for reaction is 1, 3-diamino-dipropanol or 2, 4-diaminophenol.

Preferably, the catalyst is one of sodium phosphite, sodium hypophosphite and zinc acetate.

Preferably, the solvent A, the solvent B and the solvent C respectively comprise at least one of water, methanol and ethanol.

The invention also provides the ultrahigh-toughness branched polyamide copolymer prepared by the method.

Has the advantages that: the prepared polyamide copolymer has excellent mechanical property and tensile toughness of 295.7MJ/M³The water absorption rate is low, the melting point is between 120-170 ℃, the degradation temperature is higher than 350 ℃, the processing window temperature is wide, and the method is suitable for the application fields of melt blending toughening, melt extrusion spinning, blown film, hot melt adhesive and the like.

The invention has the advantages that: the invention can regulate and control the network structure of the polyamide copolymer by regulating the amount of diamine with side groups which react to obtain the polyamide copolymer with different performances, and the prepared polyamide copolymer has excellent mechanical property and tensile fracture toughness of 295.7MJ/M³The water absorption rate is low, the melting point is between 120-170 ℃, the degradation temperature is higher than 350 ℃, the processing window temperature is wide, and the method is suitable for the application fields of melt blending toughening, melt extrusion spinning, blown film, hot melt adhesive and the like.

Meanwhile, the amide salt prepared by using the diamine without the side group is in a liquid state, can be well and uniformly mixed with the amide salt in a solid state to obtain a uniform amide salt solution, and the liquid amide salt has the advantages of high heat transfer rate and uniform heat transfer, and is not easy to cause the problem of nonuniform material reaction degree caused by local overheating frequently generated in melt polymerization.

Drawings

FIG. 1 is a structural formula of an amide salt formed by a dibasic acid and a diamine in an embodiment of the present invention;

FIG. 2 is a structural formula and a nuclear magnetic resonance spectrum of an amide salt formed by 1, 3-diamino-2-propanol and sebacic acid in example of the present invention;

FIG. 3 is a structural formula and a nuclear magnetic resonance spectrum of an amide salt of 1, 3-diamino-2-propanol and azelaic acid in the example of the present invention;

FIG. 4 is a structural formula and a nuclear magnetic resonance spectrum of amide salt formed by dimethyl pentanediamine and sebacic acid in the embodiment of the invention;

FIG. 5 is a structural formula and a nuclear magnetic resonance spectrum of an amide salt formed by 1, 2-propanediamine and sebacic acid in example of the present invention;

FIG. 6 shows a network structure of polyamide copolymer obtained by melt polycondensation of amide salt according to an embodiment of the present invention;

FIG. 7 is a Fourier infrared spectrum of a polyamide copolymer of examples 2, 3 and 4 of the present invention;

FIG. 8 is a graph showing the weight loss on heating of the polyamide copolymer in examples of the present invention and comparative examples;

FIG. 9 is a DSC of polyamide copolymers in examples of the present invention and comparative examples;

FIG. 10 is a graph showing mechanical tensile properties of polyamide copolymers in examples of the present invention and comparative examples.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments 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, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. 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.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.

Example 1

The preparation method of the ultrahigh-toughness branched polyamide copolymer specifically comprises the following steps:

(1) 202g of sebacic acid are dissolved by heating to 60 ℃ with 600ml of ethanol, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after about 10h of mixing, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate to about 70% of an amide salt solution B which is a non-branched amide salt for further use.

(2) Heating and dissolving 4.2g of sebacic acid by using 15ml of ethanol, diluting 1.8g of 1, 3-diamino-2-propanol by using 10ml of ethanol, dropwise adding the diluted solution into the dissolved diacid solution, mixing for about 10 hours, measuring the pH value of the solution, adjusting the pH value to 6.5-7.5, filtering and collecting the generated precipitate, and drying the precipitate in a vacuum drying oven at 50 ℃ for 12 hours to obtain amide salt C which is branched amide salt.

(3) Adding the concentrated amide salt solution B which cannot be branched and the branched amide salt C into a high-temperature high-pressure reaction kettle, adding 1 percent of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃, carrying out prepolymerization for 2h, and removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The polyamide copolymer obtained in example 1 had a molar ratio of unbranched amide salt to branched amide salt of 98:2, wherein the mass of the unbranched amide salt was 318g, the relative molecular mass of the unbranched amide salt was 318g/mol, the mass of the branched amide salt was 6g, the relative molecular mass of the branched amide salt was 292g/mol, and the molar ratio of the two was 98: 2.

Example 2

The preparation method of the ultrahigh-toughness branched polyamide copolymer specifically comprises the following steps:

(1) 202g of sebacic acid are dissolved by heating to 60 ℃ with 600ml of ethanol, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after about 10h of mixing, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate to about 70% of an amide salt solution B which is a non-branched amide salt for further use.

(2) 6.4g sebacic acid was dissolved by heating with 20ml ethanol, 2.9g1, 3-diamino-2-propanol was diluted with 20ml ethanol and added dropwise to the dissolved diacid solution, after mixing for about 10 hours, the pH was measured and adjusted to 6.5-7.5, and the resulting precipitate was collected by filtration and dried in a vacuum oven at 50 ℃ for 12 hours to give amide salt C as a branched amide salt.

(3) Adding the concentrated amide salt solution B which cannot be branched and the branched amide salt C into a high-temperature high-pressure reaction kettle, adding 1 percent of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃, carrying out prepolymerization for 2h, and removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The molar ratio of unbranched amide salt to branched amide salt in the polyamide copolymer obtained in example 2 was 97:3, and the calculation procedure was the same as in example 1.

Example 3

The preparation method of the ultrahigh-toughness branched polyamide copolymer specifically comprises the following steps:

(1) 202g of sebacic acid are dissolved by heating to 60 ℃ with 600ml of ethanol, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after about 10h of mixing, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate to about 70% of an amide salt solution B which is a non-branched amide salt for further use.

(2) 10.7g of sebacic acid was dissolved by heating with 40ml of ethanol, 4.8g of 1, 3-diamino-2-propanol was diluted with 20ml of ethanol and added dropwise to the dissolved diacid solution, after mixing for about 10 hours, the pH was measured and adjusted to 6.5-7.5, and the resulting precipitate was collected by filtration and dried in a vacuum oven at 50 ℃ for 12 hours to obtain amide salt C which is a branched amide salt.

(3) Adding the concentrated amide salt solution B which cannot be branched and the branched amide salt C into a high-temperature high-pressure reaction kettle, adding 1 percent of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃, carrying out prepolymerization for 2h, and removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The molar ratio of unbranched amide salt to branched amide salt in the polyamide copolymer obtained in example 3 was 95:5, and the calculation procedure was the same as in example 1.

Example 4

The preparation method of the ultrahigh-toughness branched polyamide copolymer specifically comprises the following steps:

(1) 202g of sebacic acid are dissolved by heating to 60 ℃ with 600ml of ethanol, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after about 10h of mixing, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate to about 70% of an amide salt solution B which is a non-branched amide salt for further use.

(2) Heating and dissolving 22.5g of sebacic acid by using ethanol, diluting 10g of 1, 3-diamino-2-propanol by using ethanol, dropwise adding the diluted solution into the dissolved diacid solution, mixing for about 10 hours, measuring the pH value, adjusting the pH value to 6.5-7.5, filtering and collecting the generated precipitate, and drying the precipitate in a vacuum drying oven at the temperature of 50 ℃ for 12 hours to obtain amide salt C which is branched amide salt.

(3) Adding the concentrated amide salt solution B which cannot be branched and the branched amide salt C into a high-temperature high-pressure reaction kettle, adding 1 percent of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃, carrying out prepolymerization for 2h, and removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The molar ratio of unbranched amide salt to branched amide salt in the polyamide copolymer obtained in example 4 was 90:10, and the calculation procedure was the same as in example 1.

Example 5

The preparation method of the ultrahigh-toughness branched polyamide copolymer specifically comprises the following steps:

(1) 188g of azelaic acid are dissolved by heating with 600ml of ethanol to 60 ℃, 116g of dimethylpentanediamine are diluted with ethanol and added dropwise to the dissolved diacid solution, after mixing for about 10h, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate it into about 60-80% of the amide salt solution B, which is a non-branched amide salt, for further use.

(2) 9.9g of azelaic acid was dissolved by heating with ethanol, 4.8g of 1, 3-diamino-2-propanol was diluted with ethanol and added dropwise to the dissolved diacid solution, after mixing for about 10 hours, the pH was measured and adjusted to 6.5-7.5, the resulting precipitate was collected by filtration and dried in a vacuum oven at 50 ℃ for 12 hours to give amide salt C, which is a branched amide salt.

(3) Adding the concentrated amide salt solution B which cannot be branched and the branched amide salt C into a high-temperature high-pressure reaction kettle, adding 1 percent of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃, carrying out prepolymerization for 2h, and removing water generated by the reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The polyamide copolymer obtained in example 5 had a molar ratio of unbranched amide salt to branched amide salt of 95:5, wherein the mass of the unbranched amide salt was 304g, the relative molecular mass of the unbranched amide salt was 304g/mol, the mass of the branched amide salt was 14.7g, and the relative molecular mass of the branched amide salt was 278g/mol, with a molar ratio of 95: 5.

Comparative example 1

A process for the preparation of a polyamide copolymer comprising the steps of:

(1) 202g of sebacic acid are dissolved by heating to 60 ℃ with 600ml of ethanol, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after about 10h of mixing, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to concentrate to about 70% of an amide salt solution B which is a non-branched amide salt for further use.

(2) Adding the concentrated amide salt solution into a high-temperature high-pressure reaction kettle, adding 1% of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃ to perform prepolymerization for 2h, and removing water generated by reaction by using a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The polyamide copolymer obtained by comparative example 1 had a molar ratio of unbranched amide salt to branched amide salt of 100: 0.

Comparative example 2

A process for the preparation of a polyamide copolymer comprising the steps of:

(1) 188g of azelaic acid are dissolved by heating with 600ml of ethanol to 60 ℃, 116g of dimethylpentanediamine are diluted with 200ml of ethanol and added dropwise to the dissolved diacid solution, after mixing for about 10h, the pH is measured and adjusted to 6.5-7.5, and the solvent is evaporated by heating to a concentration of about 70% of the amide salt solution, which is the unbranched amide salt, for further use.

(2) Adding the concentrated amide salt solution which cannot be branched and the branched amide salt into a high-temperature high-pressure reaction kettle, adding 1% of catalyst sodium hypophosphite by weight, firstly heating to 100 ℃, keeping the temperature for 2h to remove ethanol solvent and water, slowly heating to 150 ℃ to perform prepolymerization for 2h, and removing water generated by reaction through a purge gas to form a prepolymer with certain viscosity. And heating to 200-280 ℃, removing water generated by the reaction by vacuumizing, finishing the reaction after about 6 hours, stopping heating, and pressurizing and discharging in a nitrogen atmosphere to obtain a polyamide copolymer finished product.

The polyamide copolymer obtained by comparative example 2 had a molar ratio of unbranched amide salt to branched amide salt of 100: 0.

Experimental data and characterization:

FIG. 1 shows the structural formula of amide salt formed by dibasic acid and diamine, and the diamine with side group and dibasic acid can also be well salified, such as the structural formula of amide salt formed by 1, 3-diamino-2-propanol, dimethyl pentanediamine, 1, 2-propane diamine, sebacic acid and azelaic acid, which are respectively shown in FIGS. 2-5.

The ultrahigh-toughness polyamide copolymer obtained by melt polycondensation of the amide salt comprises a branched part and an unbranched part, and the specific structural formulas of the two parts are as follows:

wherein R is in the main chain₁Is one or several methylene groupsCyclohexyl, phenyl, etc., side group R₂Being methyl or the like, side groups R₃Hydroxyl, and the like. Ester bonds are produced in the branched molecular chain segments, while the unbranched parts are conventional polyamide chain segments. Wherein n and m are integers, n is more than or equal to 60 and less than or equal to 200, and m is more than or equal to 0 and less than or equal to 20.

The amide salt is subjected to melt polycondensation to obtain a polyamide copolymer network structural formula, and the schematic diagram is shown as 6.

The structure of the polyamide copolymer was characterized by Fourier transform infrared spectroscopy, as shown in FIG. 7, which is apparent from the infrared spectroscopy data of examples 2, 3 and 4, except for 1740cm^-1The ester group is relatively increased along with the increase of the branching degree, and other peaks are unchanged, so that the diamine added in the branching reaction can not greatly change the structure of the polymer.

According to standard ISO 62 method 4. The polyamide copolymer is tested for water absorption, and in example 1, the polyamide copolymer is placed at 50% humidity and 22 ℃ for 24 hours, the water absorption is 0.45-0.48%, and the total water absorption is 4.3-4.8%; example 2 was allowed to stand at 50% humidity and 22 ℃ for 24 hours, and the water absorption rate was 0.43 to 0.47% and the total water absorption rate was 4.2 to 4.7%.

The thermal degradation performance of the polyamide copolymer is characterized by a thermogravimetric analyzer, the test result is shown in figure 8, the degradation temperatures are all larger than 300 ℃, the thermal stability is good, the initial degradation temperature is 320-350 ℃, and the initial degradation temperature is slightly reduced along with the increase of the branching degree.

The thermodynamic properties of the polyamide copolymer are characterized by using a Differential Scanning Calorimeter (DSC), and the measurement results are shown in FIG. 9, wherein the glass transition temperature is not changed much and is about 35-40 ℃, but the melting point of the polyamide copolymer is reduced from 162 ℃ to 151 ℃ along with the increase of the branching degree, and simultaneously the melting peak is reduced and gradually changes from two melting peaks to one melting peak.

The polyamide copolymer is prepared into a sheet by a vacuum molding press, the sheet is cut into a standard sample strip by a dumbbell type cutter, and the mechanical tensile property is tested according to the standard ISO527-1, wherein the tensile speed is 10mm/min, and the environmental temperature is 20-25 ℃. The measurement results are shown in table 1 and fig. 10. It can be seen that the strain of the polyamide copolymer decreases with increasing branching, but the yield stress increases accordingly, with the maximum stress increasing and then decreasing simultaneously with decreasing strain. The toughness of the polyamide copolymers also shows a tendency to increase first and then decrease.

Table 1 shows the properties and test results of the polyamide copolymers of examples 1 to 5

From the mechanical property analysis in table 1 and fig. 10, it can be seen that the yield strength of the polyamide copolymer prepared by adding the branched amide salt is improved, the yield strength of the unbranched polyamide is about 5MPa in comparative example 1 and about 10MPa in comparative example 2, and the yield strength of the branched polyamide copolymer is above 20MPa and even above 30 MPa. At lower branching levels, as in example 1, the toughness is also increased to a higher degree, and the toughness is calculated from the stress-strain curve to be 295.7MJ/M³Greater than the toughness of the unbranched polyamide. When the degree of branching is higher, the yield strength is further increased since the polymer network structure is fixed, but the toughness begins to decrease. Due to the difference of polymer network structures formed by different branching degrees, the copolymer obtained by copolymerizing the unbranched amide salt solution and the branched amide salt has larger difference of the performances compared with the polymer prepared by singly adopting the unbranched amide salt.

Hydroxyl in the branched amide salt does not react with carboxyl at low temperature, condensation of carboxyl and amino mainly occurs at the early stage of polymerization reaction, the copolymer mainly performs prepolymerization reaction, and esterification reaction of carboxyl and hydroxyl can occur after the temperature rises to more than 200 ℃ at the later stage of reaction to form a branched structure. The branched structure formed at this time imparts more excellent properties to the polymer.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.