Intrinsic copolymerized low-temperature toughened polyamide resin and preparation method thereof

Abstract

The invention discloses intrinsic copolymerized low-temperature toughened polyamide resin which comprises a polyamide component and a flexible chain segment component, and the molar ratio of the polyamide component to the flexible chain segment component is 98.5: 1.5-85: 15; the invention also discloses a preparation method of the intrinsic copolymerized low-temperature toughened polyamide resin, which comprises the following steps: mixing a polyamide component and a flexible chain segment component, and carrying out polymerization reaction in a sectional or continuous manner, and comprises a pre-polymerization process and a post-polymerization process; the intrinsic copolymerized low-temperature toughened polyamide resin obtained by the preparation method disclosed by the invention keeps excellent mechanical strength and modulus while improving low-temperature resistance of the intrinsic copolymerized low-temperature toughened polyamide resin.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, specifically relating to an intrinsic copolymer low-temperature toughened polyamide resin and its preparation method. Background Technology

[0002] Due to its lightweight, high strength, good heat resistance, excellent wear resistance, and superior chemical resistance, polyamide resins have been widely used in engineering plastics, synthetic fibers, plastic films, coatings, and adhesives. However, at low temperatures, the molecular chain movement of polyamides is restricted, leading to increased brittleness and a tendency to break, especially for polyamide resins with shorter carbon chain numbers such as PA56 and PA66. This limits their application in cold regions or under low-temperature conditions.

[0003] The main way to improve the low-temperature toughness of polyamide resin materials is to blend them with elastomer toughening agents such as EPDM rubber and thermoplastic elastomers. One method is to simply blend EPDM rubber, natural rubber, etc., with polyamide resin, but this results in poor interfacial compatibility and uneven dispersion, leading to a sharp decrease in material strength. Another method is to blend maleic anhydride-grafted elastomers, such as EPDM rubber and polyolefin elastomers, with polyamide resin. Introducing maleic anhydride, which can react with polyamide resin, increases the chemical bonding interface and improves compatibility, but this still leads to a reduction in material strength, as described in CN103951969. A third method is to blend styrene-based thermoplastic elastomers, thermoplastic polyolefin elastomers, etc., with polyamide resin, but this often requires the addition of compatibilizers, and achieving a good toughening effect often requires a high amount, creating a significant trade-off between toughness and rigidity. In addition, short-chain polyamides can be copolymerized with long-chain polyamides to achieve low-temperature toughening modification. For example, CN102146160 publicly reported that caprolactam and dodecalactam were copolymerized to obtain polyamide materials with good toughness, but they also have the problem of a sharp decrease in strength.

[0004] In addition, introducing flexible segments into polyamide resins is also a way to improve their low-temperature resistance. CN117700723 discloses that flexible segment polyester polyols are copolymerized into the molecular chain to obtain low-temperature toughened polyamide resins. When the content of polyester polyols is high, the low-temperature toughness can be significantly improved, but it will lead to a significant reduction in its strength and modulus. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing an intrinsically copolymerized low-temperature toughened polyamide resin obtained by copolymerizing polyamide components and flexible segment components. The low-temperature resistance of the polyamide resin is greatly improved, and the low-temperature embrittlement temperature can be reduced by at least 30°C, while retaining its excellent mechanical strength and modulus.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned copolymerized low-temperature toughened polyamide resin.

[0007] The present invention provides an intrinsically copolymerized low-temperature toughened polyamide resin, which comprises a polyamide component and a flexible segment component, wherein the molar percentage of the polyamide component and the flexible segment component is 98.5:1.5 to 85:15.

[0008] The present invention provides an intrinsically copolymerized low-temperature toughened polyamide resin, wherein the polyamide component is composed of 1,5-pentanediamine or 1,6-hexanediamine and C6-C 12 It is obtained by dehydration condensation polymerization of any one of the linear aliphatic dicarboxylic acids in an equimolar ratio of polyamide salts.

[0009] The present invention provides an intrinsically copolymerized low-temperature toughened polyamide resin, wherein the flexible segment component is composed of bi-terminated amino-ether amines with a number average molecular weight of 230-2000 and C6-C 14 It is obtained by dehydration condensation polymerization of any one of the following: straight-chain aliphatic dicarboxylic acids, branched aliphatic dicarboxylic acids, cyclohexyl-containing dicarboxylic acids, or aromatic dicarboxylic acids in equimolar ratio.

[0010] The present invention provides an intrinsic copolymer low-temperature toughened polyamide resin, wherein when the molecular weight of the polyetheramine is not less than 230 and less than 800, the molar percentage of the polyamide component and the flexible segment component is not less than (85:15) and not greater than (92.5:7.5); when the molecular weight of the polyetheramine is not less than 800 and less than 1400, the molar percentage of the polyamide component and the flexible segment component is not less than (92.5:7.5) and not greater than (95:5); when the molecular weight of the polyetheramine is not less than 1400 and not greater than 2000, the molar percentage of the polyamide component and the flexible segment component is not less than (95:5) and not greater than (98.5:1.5).

[0011] The present invention provides a method for preparing the above-mentioned intrinsic copolymer low-temperature toughened polyamide resin. This method involves mixing a polyamide component and a flexible segment component and then carrying out a polymerization reaction in a segmented or continuous manner. The method includes a pre-polymerization process and a post-polymerization process, the specific process of which is as follows: (1) Prepolymerization process: The polyamide component and flexible segment component mixed in molar ratio are added to the reaction vessel, and an amidation catalyst is added at the same time. After purging with nitrogen, the mixture is heated to the set temperature under nitrogen protection and stirred at normal pressure for 4-10 hours; wherein, the molar ratio is (0.98-0.85):(0.02-0.15); the set temperature is 160~230℃, preferably 180~210℃; the amidation catalyst is 0.05~0.15wt% of the mixture mass. In the prepolymerization process, polymerization can also be carried out under positive pressure as needed. The final pressure reached by positive pressure polymerization is 0.1-1.5MPa, preferably 0.5-1MPa.

[0012] (2) Post-polymerization process: To further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to a set gradient temperature in a reaction vessel and reacted continuously at atmospheric pressure. After the reaction, it is cooled to room temperature to obtain polyamide resin. The set gradient temperatures are 230~250℃, 245~260℃, and 260~280℃, with reaction times of 1~2.5 hours, 1~2 hours, and 0.5~1.5 hours for each temperature range, respectively. In the post-polymerization process, polymerization at a third temperature range can also be carried out under reduced pressure as needed. The final pressure reached by reduced pressure polymerization is 100~4000 Pa, preferably 200~1000 Pa.

[0013] The amidation catalysts used in the above methods are commonly used catalysts for polyamide reactions, and are usually any one of potassium hypophosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, zinc hypophosphite, potassium hypophosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, zinc hypophosphite, potassium phosphate, magnesium phosphate, calcium phosphate, zinc phosphate, hypophosphite, phosphoric acid, and phosphoric acid.

[0014] Without impairing the effectiveness of the present invention, the above-mentioned intrinsic copolymer low-temperature toughened polyamide resin provided by the present invention may also be supplemented with additives including, but not limited to, flame retardants, antistatic agents, antioxidants, heat stabilizers, light stabilizers, colorants, ultraviolet absorbers and antibacterial agents during or after the polymerization reaction as needed.

[0015] Compared with the prior art, the present invention has the following advantages: The intrinsic copolymer low-temperature toughened polyamide resin of the present invention significantly increases the flexibility of the molecular chain segments by introducing flexible polyetheramine components into the molecular chain, thereby improving its low-temperature resistance and avoiding the problems of interfacial compatibility and high addition amount that exist in blend modification. At the same time, the intrinsic copolymer low-temperature toughened polyamide resin of the present invention, by reasonably controlling the content of flexible polyetheramine components, enables the polyamide resin to retain its excellent mechanical strength and modulus while improving its low-temperature resistance. Attached Figure Description

[0016] Figure 1 The image shows the infrared spectrum of the intrinsic copolymer low-temperature toughened polyamide resin prepared in Example 2 of this invention. The value at 3305 cm⁻¹ is also shown. -1 1636cm -1 、 and 1539 cm -1 Characteristic peaks corresponding to the NH group, amide I band, and amide II band appeared at 1094 cm⁻¹, respectively. -1 The presence of characteristic peaks corresponding to the COC bonds in the polyetheramine confirms the successful synthesis of the intrinsically copolymerized low-temperature toughened polyamide resin.

[0017] Figure 2 The image shows a differential scanning calorimetry (DSC) curve of the intrinsic copolymer low-temperature toughened polyamide resin prepared in Example 2 of this invention. The curve shows that the intrinsic copolymer low-temperature toughened polyamide resin has a melting point of 214.1℃; a sharp crystallization peak appears at 153.9℃, indicating that it has excellent crystallization properties.

[0018] Figure 3 This is a thermal stability test curve of the intrinsic copolymer low-temperature toughened polyamide resin prepared in Example 2 of the present invention. The graph shows the initial thermal decomposition temperature (T0) of the silicon-containing copolymer aliphatic long-chain polyamide resin. 5% The temperature can reach 421.3℃, indicating that it has excellent thermal stability. Detailed Implementation

[0019] The following embodiments are provided to further illustrate the present invention. It should be noted that the following descriptions are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the following embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. In particular, it is emphasized that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0020] It is worth noting that: 1) The relative viscosity of the intrinsic copolymer low-temperature toughened polyamide resin prepared in the following examples was measured at 25°C using an Ubbelohde viscometer with a concentration of 1.0 g / dl prepared as a solvent, using 96% concentrated sulfuric acid. 2) The embrittlement temperature test was conducted using a low-temperature impact tester according to GB / T 5470-2008. 3) The notched impact strength test of a simply supported beam was conducted using an impact tester at -30°C according to the GB / T 1043.1-2008 test standard. 4) The tensile properties test was conducted using a CMT 4104 universal testing machine (Shenzhen Xin Sansi Materials Testing Co., Ltd.) according to the GB / T1040-92 test standard, with a tensile rate of 50.0 mm / min. -1 . Example 1

[0021] (1) Prepolymerization process: The polyamide salt composed of 1,6-hexanediamine and sebacic acid mixed in a molar ratio of 90:10 and the mixture composed of double-terminated amino polyetheramine with a molecular weight of 400 and sebacic acid were added to the reaction vessel. At the same time, 0.05wt% hypophosphite was added. After purging with nitrogen, the temperature was raised to 200℃ under nitrogen protection and the reaction was stirred for 6 hours under a pressure of 1MPa.

[0022] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to 240°C for 2 hours, 260°C for 2 hours, and 270°C and reduced to 700Pa for 1.5 hours in a reaction vessel. After the reaction, it is cooled to room temperature to obtain polyamide resin. Example 2

[0023] (1) Prepolymerization process: The polyamide salt composed of 1,6-hexanediamine and dodecanoic acid mixed in a molar ratio of 92.5:7.5 and the mixture composed of 400-molecular-weight diamine-terminated polyetheramine and dodecanoic acid were added to the reaction vessel. At the same time, 0.05wt% phosphoric acid was added. After purging with nitrogen, the temperature was raised to 190℃ under nitrogen protection and the reaction was stirred for 7 hours under 1MPa pressure.

[0024] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to 230°C for 1.5 hours, 250°C for 2 hours, and 265°C and reduced to 700Pa for 1.5 hours in a reaction vessel. After the reaction, it is cooled to room temperature to obtain polyamide resin. Example 3

[0025] (1) Prepolymerization process: The polyamide salt composed of 1,5-pentanediamine and adipic acid mixed in a molar ratio of 88:12 and the mixture composed of 400-molecular-weight diamine-terminated polyetheramine and terephthalic acid were added to the reaction vessel. At the same time, 0.05wt% hypophosphite was added. After purging with nitrogen, the temperature was raised to 210°C and the reaction was stirred for 5 hours under nitrogen protection and pressure of 1.5MPa.

[0026] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained by the pre-polymerization process is heated to 240°C for 1 hour, 255°C for 1 hour, and 275°C and reduced to 1000Pa for 1 hour in a reaction vessel. After the reaction, the product is cooled to room temperature to obtain polyamide resin. Example 4

[0027] (1) Prepolymerization process: The polyamide salt composed of 1,5-pentanediamine and adipic acid mixed in a molar ratio of 96.5:3.5 and the mixture composed of bi-terminated amino polyetheramine with a molecular weight of 2000 and adipic acid were added to the reaction vessel. At the same time, 0.1wt% sodium hypophosphite was added. After purging with nitrogen, the temperature was raised to 210℃ under nitrogen protection and the reaction was stirred for 10 hours under a pressure of 0.5MPa.

[0028] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to 240°C for 2 hours, 260°C for 1 hour, and 280°C and reduced to 200Pa for 1.5 hours in a reaction vessel. After the reaction, it is cooled to room temperature to obtain polyamide resin. Example 5

[0029] (1) Prepolymerization process: The polyamide salt composed of 1,5-pentanediamine and sebacic acid mixed in a molar ratio of 95:5 and the mixture composed of 1000-molecular-weight diamine-terminated polyetheramine and adipic acid were added to the reaction vessel. At the same time, 0.06wt% sodium hypophosphite was added. After purging with nitrogen, the temperature was raised to 200℃ under nitrogen protection and the reaction was stirred for 7 hours under 1MPa pressure.

[0030] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to 230°C for 1.5 hours, 250°C for 1 hour, and 260°C and reduced to 800Pa for 1 hour in a reaction vessel. After the reaction, the product is cooled to room temperature to obtain polyamide resin. Example 6

[0031] (1) Prepolymerization process: The polyamide salt composed of 1,5-pentanediamine and dodecanoic acid mixed in a molar ratio of 90:10 and the mixture composed of dodecanoic acid and a double-terminated amino polyether amine with a molecular weight of 230 were added to the reaction vessel. At the same time, 0.05wt% phosphorous acid was added. After purging with nitrogen, the temperature was raised to 180℃ under nitrogen protection and the reaction was stirred for 4 hours under a pressure of 1.5MPa.

[0032] (2) Post-polymerization process: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to 220°C for 2 hours, 245°C for 1.5 hours, and 260°C and reduced to 1000Pa for 1.5 hours in a reaction vessel. After the reaction, it is cooled to room temperature to obtain polyamide resin.

[0033] Comparative Example 1 A polyamide salt composed of 1,6-hexanediamine and sebacic acid was added to a reaction vessel, along with 0.05 wt% hypophosphite. The polyamide resin was prepared according to the pre-polymerization and post-polymerization processes of Example 1.

[0034] Comparative Example 2 A polyamide salt consisting of 1,6-hexanediamine and sebacic acid mixed in a molar ratio of 90:10 and a mixture consisting of a 400-molecular-weight diamino-terminated polyetheramine and sebacic acid were added to a reaction vessel, along with 0.05 wt% hypophosphite. Except for adjusting the set temperature of the prepolymerization process to 240°C, the polyamide resin was prepared according to the prepolymerization and postpolymerization processes of Example 1.

[0035] Comparative Example 3 (1) Prepolymerization process: The polyamide salt composed of 1,6-hexanediamine and sebacic acid mixed in a molar ratio of 90:10 and the mixture composed of double-terminated amino polyetheramine with a molecular weight of 400 and sebacic acid were added to the reaction vessel and the prepolymerization process was carried out according to Example 1.

[0036] (2) Post-polymerization process: The product obtained from the pre-polymerization process is directly heated to 270°C in a reaction vessel and reacted for 4 hours. Then the pressure is reduced to 700Pa and reacted for 1.5 hours. After the reaction, the polyamide resin is obtained by cooling to room temperature.

[0037] relative viscosity Embrittlement temperature (°C) <![CDATA[Notched impact strength of simply supported beam (-30 °C, kJ / m 2 )]]> Yield strength (MPa) Tensile modulus (MPa) Example 1 1.8 -60 25.7 56.6 1838 Comparative Example 1 1.9 -25 5.1 56.7 1861 Comparative Example 2 1.5 -20 4.2 45.1 1557 Comparative Example 3 1.6 -25 4.7 50.3 1640 Example 2 1.9 -55 19.8 53.5 1682 Example 3 2.1 -45 10.4 79.1 2630 Example 4 2.0 -50 12.9 79.5 2653 Example 5 1.8 -55 23.5 60.2 1913 Example 6 1.8 -50 14.8 57.5 1736 As can be seen from Table 1, the intrinsic copolymer low-temperature toughened polyamide resin provided by the present invention has excellent low-temperature resistance, as well as excellent mechanical strength and modulus. The results of Example 1 and Comparative Example 1 show that by introducing the flexible polyetheramine component into the polyamide resin molecular chain within a specific range, the low-temperature resistance can be improved while retaining the excellent mechanical strength and modulus of the polyamide resin itself. As can be seen from the results of Example 1 and Comparative Examples 2 and 3, only the copolymer polyamide resin prepared under the polymerization process conditions provided by the present invention can exhibit excellent low-temperature resistance and superior mechanical strength and modulus.

Claims

1. An intrinsically copolymerized low-temperature toughened polyamide resin, characterized in that, The molecular structure comprises a polyamide component and a flexible segment component, wherein the molar percentage of the polyamide component and the flexible segment component is 98.5:1.5 to 85:

15.

2. The intrinsic copolymer low-temperature toughened polyamide resin according to claim 1, characterized in that, The polyamide component is composed of 1,5-pentanediamine or 1,6-hexanediamine and C6-C ... 12 It is obtained by dehydration condensation polymerization of any one of the linear aliphatic dicarboxylic acids in an equimolar ratio of polyamide salts.

3. The intrinsic copolymer low-temperature toughened polyamide resin according to claim 1, characterized in that, The flexible segment component is composed of bi-terminated amino-ether amines with a number average molecular weight of 230-2000 and C6-C 14 It is obtained by dehydration condensation polymerization of any one of the following: straight-chain aliphatic dicarboxylic acids, branched aliphatic dicarboxylic acids, cyclohexyl-containing dicarboxylic acids, or aromatic dicarboxylic acids in equimolar ratio.

4. The intrinsic copolymer low-temperature toughened polyamide resin according to claim 3, characterized in that, When the molecular weight of the polyetheramine is not less than 230 and less than 800, the molar percentage of the polyamide component and the flexible segment component is not less than (85:15) and not greater than (92.5:7.5); when the molecular weight of the polyetheramine is not less than 800 and less than 1400, the molar percentage of the polyamide component and the flexible segment component is not less than (92.5:7.5) and not greater than (95:5); when the molecular weight of the polyetheramine is not less than 1400 and not greater than 2000, the molar percentage of the polyamide component and the flexible segment component is not less than (95:5) and not greater than (98.5:1.5).

5. A method for preparing an intrinsically copolymerized low-temperature toughened polyamide resin, characterized in that, This method involves mixing polyamide components and flexible segment components and then carrying out a polymerization reaction in a segmented or continuous manner, including pre-polymerization and post-polymerization processes.

6. The method for preparing the intrinsic copolymer low-temperature toughened polyamide resin according to claim 5, characterized in that, The prepolymerization process is as follows: a polyamide component and a flexible segment component mixed in a molar ratio are added to a reaction vessel, along with an amidation catalyst. After purging with nitrogen, the mixture is heated to a set temperature under nitrogen protection and stirred at atmospheric pressure for 4-10 hours. The molar ratio is (0.98-0.85):(0.02-0.15). The set temperature is 160-230℃. The amidation catalyst is 0.05-0.15 wt% of the mixture.

7. The method for preparing the intrinsic copolymer low-temperature toughened polyamide resin according to claim 5, characterized in that, The prepolymerization process is as follows: Polyamide and flexible segment components, mixed in a molar ratio, are added to a reaction vessel, along with an amidation catalyst. After purging with nitrogen, the mixture is heated to a set temperature under nitrogen protection and stirred under positive pressure for 4-10 hours. The molar ratio is (0.98-0.85):(0.02-0.15); the set temperature is 160-230℃; the amidation catalyst is 0.05-0.15 wt% of the mixture; and the final pressure reached during positive pressure polymerization is 0.1-1.5 MPa.

8. The method for preparing the intrinsic copolymer low-temperature toughened polyamide resin according to claim 5, characterized in that, The post-polymerization process is as follows: In order to further increase the molecular weight, under nitrogen protection, the product obtained from the pre-polymerization process is heated to a set gradient temperature in a reaction vessel and the reaction is continued at atmospheric pressure. After the reaction, it is cooled to room temperature to obtain polyamide resin. The set gradient temperature is 230~250℃, 245~260℃, and 260~280℃, and the reaction time for each temperature is 1~2.5 hours, 1~2 hours, and 0.5~1.5 hours, respectively.

9. The method for preparing the intrinsic copolymer low-temperature toughened polyamide resin according to claim 5, characterized in that, The post-polymerization process is as follows: To further increase the molecular weight, under nitrogen protection, the product obtained from the previous polymerization process is heated to a set gradient temperature in a reaction vessel and polymerized in three temperature stages. The first and second temperature stages are continuous reactions at atmospheric pressure, while the third temperature stage is polymerized under reduced pressure. After the reaction, the product is cooled to room temperature to obtain polyamide resin. The set gradient temperatures are 230~250℃, 245~260℃, and 260~280℃, with reaction times of 1~2.5 hours, 1~2 hours, and 0.5~1.5 hours for each temperature stage, respectively. The final pressure reached during the reduced pressure polymerization in the third temperature stage is 100~4000 Pa.

10. The intrinsic copolymer low-temperature toughened polyamide resin obtained by the preparation method according to claim 5, characterized in that, One or more of the following are added during or after the polymerization reaction: flame retardant, antistatic agent, antioxidant, heat stabilizer, light stabilizer, colorant, ultraviolet absorber, and antibacterial agent.

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