A long-chain polyamide resin with easy processability and high tensile property, and a preparation method and application thereof

Abstract

The application belongs to the field of engineering plastics, and particularly relates to long-chain polyamide resin with easy processing and high tensile property, and a preparation method and application thereof. The long-chain polyamide resin comprises the following raw material components: component a: aliphatic carboxylic acid compound component; component b: polyamine compound component; and component c: a compound with a structure shown in the following formula (1), wherein n and m can be any number between 1 and 10. The long-chain polyamide resin of the application introduces structural diacid with an asymmetric benzene ring structure, utilizes the asymmetric structure to reduce the crystallinity of the material, and introduces the benzene ring structure to improve the mechanical property of the polyamide material, so that the low processing temperature is realized from the polyamide material component itself, the energy consumption is reduced, and the mechanical property of the polyamide material is ensured. The problem that the processing temperature and mechanical property of the polyamide material and the processing energy consumption are difficult to be considered in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of engineering plastics, specifically relating to a long-chain polyamide resin with easy processing and high tensile properties, its preparation method, and its applications. Background Technology

[0002] Long-chain polyamide resins are widely used in the automotive, electronics, textile, and engineering plastics industries due to their excellent mechanical properties, heat resistance, and chemical stability. However, while traditional polyamide materials possess good mechanical properties, their inherent high crystallinity and hydrogen bond network result in high processing temperatures and high energy consumption during production, contributing to their high cost. Furthermore, this has become a significant constraint in the context of increasingly scarce resources and growing emphasis on environmental protection.

[0003] To address these issues, researchers have proposed methods to modify the processing properties of polyamides by improving their molecular structure. For example, patent CN 118930845 A introduces polycyclic amine compounds into polyamide resins to form high-performance polyamides with high hydrogen bond density and crystallinity. While this polyamide exhibits an increased softening point and mechanical strength compared to the unadded compound, it does not reduce processing energy consumption. Patent US3553288A uses blending of polyamide and polyester to lower the melting point while maintaining mechanical properties; however, this also fails to reduce processing energy consumption and, in fact, leads to a further increase in energy consumption due to physical blending. Therefore, achieving low processing temperatures to reduce energy consumption while maintaining the mechanical properties of the polyamide material remains a significant technical challenge. Summary of the Invention

[0004] To address the challenge of balancing processing temperature, mechanical properties, and processing energy consumption in existing polyamide materials, this invention provides a long-chain polyamide resin with easy processing and high tensile properties, along with its preparation method and applications. By introducing a structural diacid (component c) with an asymmetric benzene ring structure, a new long-chain polyamide resin with a novel structure is prepared. The long-chain polyamide resin prepared by this invention achieves low processing temperature from the components themselves, thereby reducing processing energy consumption while ensuring that the mechanical properties of the polyamide material remain unchanged or even improved.

[0005] To solve the above problems, the technical solution of the present invention is:

[0006] In a first aspect, the present invention provides a long-chain polyamide resin that is easy to process and has high tensile properties, comprising the following raw material components:

[0007] Component a: Aliphatic carboxylic acid compounds

[0008] Component b: Polyamine compounds

[0009] Component c: A compound with the structure shown in formula (1)

[0010] Equation (1)

[0011] In equation (1), n ​​and m can be any numbers between 1 and 10.

[0012] Preferably, component c is selected from one or more of benzylsuccinic acid, 4-carboxymethylbenzoic acid, and 3-(4-carboxyphenyl)propionic acid. 4-Carboxymethylbenzoic acid is preferred. 4-(carboxymethyl)benzoic acid and 3-(4-carboxyphenyl)propionic acid are specific compounds belonging to structural formula (II) of formula (1) of component c; benzylsuccinic acid is a specific compound belonging to structural formula (III) of formula (1) of component c.

[0013] Preferably, the molar amount of carboxyl groups contained in group c) accounts for 25%-100% of the total molar amount of carboxyl groups contained in the components. The range can also be selected as 25%-50% or 50%-100%. Preferably, it is 25%-50%.

[0014] The molar ratio of carboxyl groups in component c) of this invention to the total molar ratio of carboxyl groups affects the processing temperature and material properties. By introducing a structural diacid with an asymmetric benzene ring structure, the density and strength of hydrogen bonds in the polyamide are controlled. Then, the asymmetric structure is used to reduce the crystallinity of the material, while the introduced benzene ring structure improves the mechanical properties of the polyamide material. Thus, it is possible to reduce the processing temperature of the polyamide while maintaining or even improving its mechanical properties.

[0015] Preferably, the aliphatic carboxylic acid compound is selected from one or more of adipic acid, glutaric acid, or dodecanoic acid.

[0016] Preferably, the polyamine compound is selected from one or more of pentanediamine, hexanediamine, or decanediamine.

[0017] In a second aspect, the present invention provides a method for preparing a long-chain polyamide resin that is easy to process and has high tensile properties, characterized by comprising the following steps:

[0018] Step 1: Dissolve components a and c in an organic solvent and heat the solution. Once the temperature reaches 60-100℃, add component b and react at this temperature for 20-60 minutes to obtain the polyamide prepolymer.

[0019] Step 2: The polyamide prepolymer obtained in Step 1 and the polymerization inhibitor are stirred and mixed to obtain a mixture; the mixture is heated under an inert gas atmosphere, and the reaction temperature is raised to 180°C and held for 30 min; then the reaction temperature is raised to 210°C and reacted at this temperature for 0-3 h, followed by raising the temperature to 230°C and reacting at this temperature for 4-7 h to obtain a long-chain polyamide resin. Preferably, the reaction temperature is 210°C for 3 h and 230°C for 4 h.

[0020] The mixture is heated under an inert gas atmosphere at a temperature of 180°C for 30 minutes. This is to ensure that the mixture is melted and mixed evenly, and to ensure that the polymerization inhibitor and the polyamide prepolymer are fully contacted and dispersed.

[0021] The present invention first carries out the first step of high polymerization reaction at a relatively low temperature (210°C) to prevent the salt synthesized in the first step from sublimating and volatilizing due to excessively high temperature. Then, as the molecular weight of polyamide is increased, the temperature is increased to 230°C to further increase the molecular weight of polyamide material, thereby further enhancing the mechanical properties of long-chain polyamide resin, such as tensile strength.

[0022] Preferably, the organic solvent may be selected from ethanol, tetrahydrofuran, acetone, and dichloromethane.

[0023] Preferably, the polymerization inhibitor is selected from hydroquinone, tetrachlorobenzoquinone, N-allylamide, or N,N'-diallylimide.

[0024] A third aspect of the present invention provides the application of the long-chain polyamide resin as described above or the long-chain polyamide resin obtained by the preparation method described above in flexible electronic materials or tubing.

[0025] The beneficial effects of the present invention through the above technical solution are as follows:

[0026] (1) This invention provides a method for controlling the density and strength of hydrogen bonds in polyamides by introducing a structural diacid with an asymmetric benzene ring structure. The asymmetric structure is then used to reduce the crystallinity of the material, while the introduced benzene ring structure improves the mechanical properties of the polyamide material. This allows for lower processing temperatures from the component itself, reducing processing energy consumption while maintaining or even improving the mechanical properties of the polyamide material. This method is simple, feasible, and has significant industrial application prospects. It effectively overcomes the shortcomings of existing technologies and provides an innovative solution for the production of high-performance, easily processed polyamide materials.

[0027] (2) The molar ratio of carboxyl groups in group c) of the present invention to the total molar ratio of carboxyl groups in the components affects the processing temperature and material properties. Compared with the preparation of long-chain polyamide resin using only dodecanoic acid and 4-carboxymethylbenzoic acid, which has only asymmetric benzene ring structure, the long-chain polyamide resin prepared by the present invention improves the tensile strength while reducing the melting temperature.

[0028] (3) In this invention, the first step of the high polymerization reaction is carried out at a lower temperature (210°C) to prevent the salt synthesized in the first step from sublimating and volatilizing due to excessive temperature. Then, as the molecular weight of polyamide is increased, the temperature is increased to 230°C to further increase the molecular weight of polyamide material, thereby further enhancing the mechanical properties of long-chain polyamide resin, such as tensile strength. Attached Figure Description

[0029] Figure 1 The infrared spectra of the long-chain polyamide resins prepared in Comparative Examples 1-2 and Examples 1-5 are shown.

[0030] Figure 2 The DSC curves are of the long-chain polyamide resins prepared in Comparative Examples 1-2 and Examples 1-5. Detailed Implementation

[0031] To more clearly illustrate the technical means, innovative features, and achieved objectives and effects of this invention, a clear and complete description will be provided below with specific examples. Obviously, the described examples are only a portion of the embodiments of this invention, and not all of them. Unless otherwise specified, the materials, reagents, etc., used in the embodiments of this invention can all be obtained commercially.

[0032] Comparative Example 1 (without component c)

[0033] A method for preparing a long-chain polyamide resin, comprising the following steps:

[0034] (1) Dissolve 46.06g (0.2mol) dodecanoic acid in 250ml anhydrous ethanol solvent and stir evenly. Heat the mixture until the reaction temperature rises to 80℃, then add 34.462g (0.2mol) decanediamine in molten state and react at 80℃ for 30min. After the reaction is completed, wash and dry the reaction product to obtain polyamide prepolymer.

[0035] (2) 80.522 g (99 wt%) of polyamide prepolymer obtained in step 1 (the mass of the polyamide prepolymer is the sum of the masses of the raw materials in step 1) and 0.805 g (1 wt%) of hydroquinone were mixed in a stirrer to obtain a mixture; the mixture was heated under an inert gas atmosphere, and the reaction temperature was raised to 180 °C and held for 30 min; the mixture was melted and mixed evenly to ensure that the polymerization inhibitor and the polyamide prepolymer were fully contacted and dispersed. Then the reaction temperature was raised to 210 °C and held at this temperature for 3 h, and then the temperature was raised to 230 °C and held at this temperature for 4 h to obtain long-chain polyamide resin.

[0036] Using a rapid scanning calorimeter, the nylon resin was heated to 220℃ at a rate of 10K / min and then rapidly cooled to 20℃ at a rate of 30K / min. The melting temperature was measured to be 191℃.

[0037] Using a universal electronic testing machine, a nylon resin film with a length of 100 mm, a width of 10 mm, and a thickness of 0.05 mm was prepared, and its tensile strength was measured to be 20.241 MPa.

[0038] Comparative Example 2 (without component a)

[0039] This embodiment provides a method for preparing a long-chain polyamide resin, the steps of which are as follows:

[0040] (1) Dissolve 36.04 g (0.2 mol) of 4-carboxymethylbenzoic acid in 250 ml of anhydrous ethanol solvent and stir until uniform. Heat the mixture until the reaction temperature rises to 80 °C, then add 34.462 g (0.2 mol) of decanediamine in the molten state and react at 80 °C for 30 min. After the reaction is completed, wash and dry the reaction product to obtain polyamide prepolymer.

[0041] (2) 70.502 g (99 wt%) of polyamide prepolymer obtained in step 1 (the mass of the polyamide prepolymer is the sum of the masses of the raw materials in step 1) and 0.705 g (1 wt%) of hydroquinone were added to a stirrer and mixed to obtain a mixture. The mixture was heated under an inert gas atmosphere, and the reaction temperature was raised to 180°C and held for 30 min to ensure that the mixture was melted and mixed evenly, and to ensure that the polymerization inhibitor and the polyamide prepolymer were fully contacted and dispersed. Then the reaction temperature was raised to 210°C and held at this temperature for 3 h. Subsequently, the temperature was raised to 230°C and held at this temperature for 4 h to obtain long-chain polyamide resin.

[0042] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Comparative Example 2 was measured to be 200℃, and the tensile strength was 17.217MPa.

[0043] Example 1

[0044] This embodiment provides a method for preparing a long-chain polyamide resin, the steps of which are as follows:

[0045] (1) Dissolve 34.545g (0.15 mol) dodecanoic acid and 9.01g (0.05mol) 4-carboxymethylbenzoic acid in 250ml anhydrous ethanol solvent and stir evenly. After the reaction temperature rises to 80℃, add 34.462g (0.2mol) decanediamine in molten state and react at 80℃ for 30min. After the reaction is completed, wash and dry the reaction product to obtain polyamide prepolymer.

[0046] (2) 78.017 g (99 wt%) of polyamide prepolymer obtained in step 1 (the mass of the polyamide prepolymer is the sum of the masses of the raw materials in step 1) and 0.780 g (1 wt%) of hydroquinone were mixed in a stirrer to obtain a mixture; the mixture was heated under an inert gas atmosphere, and the reaction temperature was raised to 180 °C and held for 30 min; the mixture was melted and mixed evenly to ensure that the polymerization inhibitor and the polyamide prepolymer were fully contacted and dispersed. Then the reaction temperature was raised to 210 °C and held at this temperature for 3 h, and then the temperature was raised to 230 °C and held at this temperature for 4 h to obtain long-chain polyamide resin.

[0047] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Example 1 was measured to be 160°C, and the tensile strength was 25.1502 MPa.

[0048] Example 2:

[0049] The difference between this embodiment and embodiment 1 is that in step (1), 23.03g (0.1 mol) dodecanoic acid and 18.02g (0.1 mol) 4-carboxymethylbenzoic acid are dissolved in 250ml of anhydrous ethanol and stirred evenly.

[0050] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Example 2 was measured to be 155°C, and the tensile strength was 22.941 MPa.

[0051] The present invention summarizes the melting temperature and tensile properties of the long-chain polyamide resins prepared in Comparative Examples 1-2 and Examples 1-2, as shown in Table 1.

[0052] Table 1. Properties of the long-chain polyamide resins prepared in Comparative Examples 1-2 and Examples 1-2

[0053] As shown in Table 1, compared to Comparative Examples 1 and 2, which used only dodecanoic acid and 4-carboxymethylbenzoic acid (a structural diacid with only an asymmetric benzene ring structure) to prepare long-chain polyamide resins, the long-chain polyamide resins prepared in Examples 1 and 2 of this invention improved tensile strength while lowering the melting temperature. A lower melting temperature requires less energy during processing and molding, which helps to reduce the processing temperature. Example 2, in particular, achieved the lowest melting temperature while improving tensile properties, resulting in the lowest processing temperature. This demonstrates that the materials of this invention achieve both low processing temperature and guaranteed tensile properties.

[0054] Example 3

[0055] The difference between this embodiment and Example 1 is that in step 2, the mixture is heated under an inert gas atmosphere, and the reaction temperature is raised to 180°C and held for 30 minutes to ensure that the mixture is melted and mixed evenly, thus ensuring sufficient contact and dispersion of the polymerization inhibitor and the polyamide prepolymer. Subsequently, the temperature is raised to 230°C and held at this temperature for 7 hours to obtain the long-chain polyamide resin. The other steps are the same as in Example 1.

[0056] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Example 3 was measured to be 176°C, and the tensile strength was 26.492 MPa.

[0057] Table 2 Properties of the long-chain polyamide resins prepared in Examples 1 and 3

[0058] Compared with Example 3, the long-chain polyamide resin prepared by step 2 in Example 1 using staged heating reduces the processing temperature of the polyamide while reducing the crystallinity of the long-chain polyamide resin, and basically maintains little change in the mechanical properties of the material.

[0059] Example 4

[0060] The difference between this embodiment and Example 1 is that in step 1, 34.545g (0.15 mol) dodecanoic acid and 9.709g (0.05mol) 3-(4-carboxyphenyl)propionic acid are dissolved in 250ml of anhydrous ethanol and stirred until homogeneous.

[0061] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Example 4 was measured to be 178°C, and the tensile strength was 22.426 MPa.

[0062] Table 3 Properties of the long-chain polyamide resins prepared in Examples 1 and 4

[0063] Compared to Example 4 which uses 3-(4-carboxyphenyl)propionic acid, Example 1, which uses 4-carboxymethylbenzoic acid as a structural diacid with an asymmetric benzene ring structure, produces a long-chain polyamide resin with a lower melting temperature, higher tensile strength, and lower crystallinity. Therefore, the long-chain polyamide resin prepared using 4-carboxymethylbenzoic acid as a structural diacid with an asymmetric benzene ring structure achieves a lower processing temperature while maintaining high mechanical properties.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 2 is that in step 1, 23.03g (0.1 mol) dodecanoic acid and 20.821g (0.1 mol) benzylsuccinic acid are dissolved in 250ml of anhydrous ethanol and stirred until homogeneous.

[0066] Using the same testing method as Comparative Example 1, the melting temperature of the long-chain polyamide resin prepared in Example 5 was measured to be 168°C, and the tensile strength was 14.94 MPa.

[0067] Table 4. Properties of the long-chain polyamide resins prepared in Examples 2 and 5

[0068] Compared with benzylsuccinic acid in Example 5, the long-chain polyamide resin prepared in Example 2 of the present invention using 4-carboxymethylbenzoic acid as a structural diacid with an asymmetric benzene ring structure has a lower melting temperature and a higher tensile strength. Therefore, the long-chain polyamide resin prepared using 4-carboxymethylbenzoic acid as a structural diacid with an asymmetric benzene ring structure achieves a lower processing temperature for polyamides while maintaining high mechanical properties of the material.

[0069] Figure 1 The infrared spectra of the long-chain polyamide resins prepared in Comparative Examples 1-2 and Examples 1-5 are shown. The characteristic absorption peak of NH stretching vibration is near 3300 cm⁻¹, indicating the presence of amide groups (-CONH-) in the polyamide. The characteristic absorption peak of CH stretching vibration of benzene ring is near 3080 cm⁻¹, indicating that the polyamide may contain a benzene ring structure. The characteristic absorption peak of C=O stretching vibration is near 1635 cm⁻¹, further confirming the presence of amide groups. The characteristic absorption peak of NH bending vibration is near 1547 cm⁻¹, which is related to amide groups.

[0070] Figure 2 The DSC curves are for the long-chain polyamide resins prepared in Examples 1-6. A rapid scanning calorimeter was used for testing. The nylon resin was heated to 220°C at a rate of 10 K / min, and then rapidly cooled to 30°C at a rate of 30 K / min, repeated twice. The melting temperatures of the long-chain polyamide resins in Examples 1-5 and Comparative Examples 1-2 were measured.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A long-chain polyamide resin with easy processing and high tensile properties, characterized in that, It includes the following raw material components: Component a: an aliphatic carboxylic acid compound; the aliphatic carboxylic acid compound is dodecanoic acid; Component b: a polyamine compound; the polyamine compound is decanediamine; Component c: selected from one or more of benzylsuccinic acid, 4-carboxymethylbenzoic acid, and 3-(4-carboxyphenyl)propionic acid; the molar amount of carboxyl groups contained in component c accounts for 25%-50% of the molar amount of carboxyl groups contained in the total components.

2. A method for preparing the easily processed and high tensile strength long-chain polyamide resin according to claim 1, characterized in that, Includes the following steps: Step 1: Dissolve components a and c in an organic solvent and heat the mixture until the temperature reaches 60-100℃. Then add component b and react at this temperature for 20-60 minutes to obtain the polyamide prepolymer. Step 2: Stir and mix the polyamide prepolymer and polymerization inhibitor obtained in Step 1 to obtain a mixture; heat the mixture under an inert gas atmosphere and raise the reaction temperature to 180℃ and hold for 30 min; then raise the reaction temperature to 210℃ and react at this temperature for 0-3 h, then raise the temperature to 230℃ and react at this temperature for 4-7 h to obtain long-chain polyamide resin.

3. The method for preparing the easily processed and high tensile strength long-chain polyamide resin according to claim 2, characterized in that, The organic solvent is selected from one of ethanol, tetrahydrofuran, acetone, and dichloromethane.

4. The method for preparing the easily processed and high tensile strength long-chain polyamide resin according to claim 2, characterized in that, The polymerization inhibitor is selected from hydroquinone, tetrachlorobenzoquinone, and N-allylamide.

5. The application of the long-chain polyamide resin according to claim 1 or the long-chain polyamide resin obtained by the preparation method according to any one of claims 2-4 in flexible electronic materials or tubing.

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