A bio-based long carbon chain polyamide and a method of making the same

Abstract

The application relates to the field of high polymer synthesis chemistry and discloses a bio-based long carbon chain polyamide and a preparation method thereof. In the method, dimeric acid or hydrogenated dimeric acid, decamethylenediamine and a catalyst are added into a reaction kettle to carry out a polycondensation reaction under the condition of inert gas protection, long carbon chain polyamides with different molecular weights are prepared by adjusting the polymerization temperature, the reaction time, the type of the catalyst and the acid-amine ratio, the obtained long carbon chain polyamides have good thermal stability and mechanical properties, the melting point is 70-90 DEG C, the maximum thermal decomposition temperature is 440-480 DEG C, the tensile strength is 10-35 MPa, and the elongation at break is 500-1500%. Meanwhile, the material has high light transmittance, low haze and excellent elastic recovery performance, the elastic recovery rate can be more than 90%. In addition, the polyamide material can be depolymerized and recycled through a chemical method, and the monomers can be recycled. The method has the advantages of wide raw material sources, simple process and easy industrial production.

Description

Technical Field

[0001] This invention relates to the field of polymer synthetic chemistry, and in particular to a bio-based long carbon chain polyamide and its preparation method. Background Technology

[0002] Long-chain polyamides are an important class of high-performance engineering materials, whose molecular chains typically contain repeating units of more than ten carbon atoms. Compared with traditional short-chain polyamides, long-chain polyamides exhibit lower water absorption, excellent dimensional stability, and good flexibility due to their lower amide group density and higher molecular chain flexibility. Furthermore, these materials generally possess good processing flowability, making them suitable for various processing methods such as injection molding and extrusion. Therefore, they have broad application prospects in automotive parts, electronics, sporting goods, and functional materials.

[0003] Dimer acids are bio-based dicarboxylic acid monomers derived from natural vegetable oils (such as canola oil and soybean oil), possessing long aliphatic carbon chain structures. Bio-based long-chain polyamide materials can be prepared by polycondensation reactions of dimer acids and diamines. Because dimer acid molecules contain long, flexible segments and certain branched or cyclic structures, these structures can reduce the regularity of hydrogen bonds between polymer molecular chains, thereby reducing the crystallinity of the material and improving the flexibility of the molecular chains. Therefore, long-chain polyamides prepared from dimer acids typically exhibit good flexibility and processing properties, showing potential application value in low-temperature environment materials and flexible materials.

[0004] However, existing long-chain polyamide materials still have certain shortcomings in some aspects. For example, their elastic recovery ability under large strain conditions is limited, making it difficult to meet the application requirements of highly elastic materials. Simultaneously, the mechanical properties of some polyamide materials tend to degrade at low temperatures, limiting their application in extreme environments. Furthermore, traditional polyamide materials are often difficult to recycle efficiently through chemical depolymerization, hindering their recycling and sustainable development. Therefore, developing a bio-based long-chain polyamide with excellent elastic properties, good low-temperature resistance, and chemical depolymerization and recycling characteristics, along with its preparation method, is of great significance for expanding the applications of long-chain polyamides in flexible materials, low-temperature materials, and recyclable polymer materials. Summary of the Invention

[0005] Purpose of the invention: The present invention aims to solve the problems of insufficient elastic recovery, poor low-temperature performance and difficulty in recycling of existing polyamide materials, and provides a bio-based long carbon chain polyamide and its preparation method.

[0006] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0007] In a first aspect, the present invention provides a long-chain polyamide with the structure shown in formulas Ia, Ib, Ic, Id, Ie and If.

[0008]

[0009]

[0010] Where m is selected from any integer from 10 to 500;

[0011] This invention introduces a long carbon chain structure, which gives the polymer molecular chain high flexibility, thereby endowing the material with excellent elastic properties and good low-temperature mechanical properties.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned long-chain polyamide, comprising adding dimer acid or hydrogenated dimer acid and decanediamine monomer to a reaction vessel under inert gas protection to carry out a polycondensation reaction, thereby obtaining the long-chain polyamide.

[0013] The method includes the following steps: under an inert atmosphere, dimer acid or hydrogenated dimer acid, decanediamine, and a catalyst are added to a high-pressure reactor for a polycondensation reaction; the reaction is first heated to temperature T1 and maintained for time B1 to complete the pre-reaction process, and then further heated to temperature T2 to continue the reaction; when the system pressure reaches 1.7 MPa, the pressure is maintained for time B2; then the pressure is gradually reduced to atmospheric pressure, and the reaction is further carried out under negative pressure with vacuum and stirring for time B3 to promote the polycondensation reaction; after the reaction is completed, the product is placed in deionized water and cooled to obtain the target polyamide.

[0014] The dimer acid is a dimer acid and a hydrogenated dimer acid.

[0015] The molar ratio of the dimeric acid to the decanediamine is 1:(1.01 to 1.04).

[0016] The catalyst is sodium hypophosphite, hypophosphite, sulfurous acid, phosphate ester, phosphite ester, phenyl phosphate ester, or triphenyl phosphite ester, preferably sodium hypophosphite, and the catalyst accounts for 0.01 wt% to 5 wt% of the total weight.

[0017] Among them, the temperature of A1 is 50-90℃, the reaction time of B1 is 1-4h, the temperature of A2 is 200-280℃, the reaction time of B2 is 1-4h, and the reaction time of B3 is 1-24h.

[0018] Thirdly, through the above-mentioned structural design and control of polymerization process conditions, the long-chain polyamide prepared by this invention has excellent comprehensive properties.

[0019] The resulting material has a melting point of 70–90℃, a maximum thermal decomposition temperature of 440–480℃, a tensile strength of 10–35 MPa, an elongation at break of 500–1500%, and a toughness of 50–200 MJ / m. 3 At the same time, the material has high transparency.

[0020] Under cyclic tensile conditions, this material can maintain good elastic recovery ability within a large strain range. When cyclic tensile tests are conducted under strain conditions of 50% to 200%, its elastic recovery rate can reach more than 90%, demonstrating excellent elastic properties and cyclic stability, making it suitable for the fields of flexible and elastic materials.

[0021] Fourthly, the long-chain polyamide prepared by this invention has excellent low-temperature resistance.

[0022] In particular, the long-chain polyamide can still maintain good mechanical properties and structural stability under low-temperature conditions.

[0023] Within a temperature range of 0 to -70°C, the long-chain polyamide still exhibits high tensile strength and elongation at break, with the tensile strength being 70% to 99% at room temperature (specifically 7 to 35 MPa) and the elongation at break being 65% to 95% at room temperature (specifically 350% to 1400%), while maintaining good toughness.

[0024] Among them, under low-temperature tensile test conditions, the long carbon chain polyamide is not prone to embrittlement, thus exhibiting excellent low-temperature resistance and is suitable for the field of low-temperature resistant materials.

[0025] Fifthly, the long-chain polyamide prepared by this invention can be depolymerized and recycled through chemical methods, thereby realizing the recycling of monomers.

[0026] Specifically, heating the long-chain polyamide under acidic conditions can cause a depolymerization reaction, resulting in the polymer depolymerizing into dimer acid or hydrogenated dimer acid monomers and decanediamine monomers.

[0027] Solvent extraction and separation processes can yield high-purity recovered monomers, with recovery rates of 90%–99% for dimer acids or hydrogenated dimer acids and 85%–95% for decanediamine.

[0028] The recycled monomers can be reused in the polymerization reaction, thereby realizing the recycling of the long-chain polyamide material.

[0029] Beneficial effects:

[0030] (1) This invention provides a bio-based long-chain polyamide. By introducing a long carbon chain structure into the polymer molecular chain, the material exhibits high molecular chain flexibility, thereby endowing it with excellent comprehensive properties. The long-chain polyamide has a moderate melting point and a high thermal decomposition temperature, while also possessing good mechanical properties, including high tensile strength and elongation at break. Furthermore, the material exhibits good optical properties, displaying high light transmittance and low haze. Under cyclic tensile testing conditions, the material maintains good elastic recovery ability over a wide strain range, with an elastic recovery rate exceeding 90%.

[0031] (2) The long carbon chain polyamide prepared by the present invention has excellent low temperature resistance. It can still maintain high tensile strength and elongation at break under low temperature conditions. The material still has good mechanical properties and toughness in the temperature range of 0 to -70℃, thereby expanding the application of polyamide materials in the field of low temperature environment.

[0032] (3) The long-chain polyamide prepared by the present invention can be depolymerized and recycled by chemical methods. Under certain conditions, it can be depolymerized to generate dimer acid or hydrogenated dimer acid monomers and decanediamine monomers, thereby realizing the recycling and reuse of monomers and realizing the recycling of materials, which has good prospects for sustainable development applications. Attached Figure Description

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0034] Figure 1 The polyamide product of Example 6 1 HNMR spectrum;

[0035] Figure 2 The TGA image of the polyamide product in Example 6;

[0036] Figure 3 The DSC diagram of the polyamide product in Example 6 is shown below.

[0037] Figure 4 This is a GPC diagram of the polyamide product from Example 6.

[0038] Figure 5 The graph shows the mechanical properties of the polyamide product in Example 6. Detailed Implementation

[0039] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0040] In the following examples, the product was measured using a 400MHz Bruker nuclear magnetic resonance spectrometer: 6mg of polyamide sample was placed in an NMR tube, deuterated chloroform (CDCl3) was added, and the mixture was shaken until completely dissolved before testing.

[0041] The molecular weight of the samples was determined by a WTRFX-11 gel permeation chromatography (GPC) system with hexafluoroisopropanol as the mobile phase and a flow rate of 0.7 mL / min.

[0042] The decomposition temperature of the sample was determined using a TGA550 thermogravimetric analyzer: 5–10 mg of sample was weighed onto a platinum pan and tested under nitrogen protection at a heating rate of 20 °C / min, with a test temperature range of 30–800 °C.

[0043] The melting temperature of the samples was determined using a DSC250 differential scanning calorimeter: 5–10 mg of sample was weighed onto a platinum pan, and the test was conducted under nitrogen protection. The test program was set to first heat up, then cool down, and finally heat up again. The initial temperature was -30℃, and the final temperature was the temperature corresponding to a 0.5% mass loss in the thermogravimetric analysis. The cooling process involved decreasing the temperature from the highest point to -30℃. Both the heating and cooling rates were 10℃ / min, and the melting point was obtained from the data obtained from the second heating scan curve.

[0044] The mechanical properties of the samples were tested using an electronic universal testing machine (TMG104). The tensile test conditions were in accordance with the national standard GB / T1040.1-2006, with a tensile rate of 50 mm / min and a test temperature of room temperature.

[0045] The elastic properties of the samples were characterized by cyclic tensile testing using an electronic universal testing machine at room temperature. Tensile strains of 50%, 100%, 150%, and 200% were set during the test, and five cycles of tensile-recovery testing were performed under each strain condition. The tensile rate was set to 50 mm / min, and the material was immediately unloaded to its initial length after reaching the set strain. The stress-strain changes and residual deformation of the material during the cycles were recorded.

[0046] The low-temperature performance test method of the sample is as follows: the sample is placed in a cold trap, immersed for 1 hour under different low-temperature conditions, and then taken out and subjected to tensile performance test on an electronic universal testing machine at a tensile rate of 50 mm / min.

[0047] The depolymerization and recovery method for the sample is as follows: Immerse the sample in 5 mol·L⁻¹ water. -1The reaction was carried out in a hydrochloric acid solution at 160°C for 10 hours. After the reaction was completed, the mixture was cooled to room temperature, and the dimer acid precipitated out. The precipitate was extracted three times with dichloromethane, and the solvent was removed by rotary evaporation to obtain the recovered dimer acid monomer. The remaining aqueous solution was neutralized with alkali to precipitate the decanediamine monomer, which was also extracted three times with dichloromethane and recovered by rotary evaporation.

[0048] Example 1:

[0049] Under an inert atmosphere, 84.14 g of dimer acid, 30.94 g of decanediamine, and 0.1151 g of sodium hypophosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 60 °C and held at that temperature for 1 h for pre-reaction. Subsequently, the temperature was increased to 240 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 2 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 6 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 90540 g / mol.

[0050] Example 2:

[0051] Under an inert atmosphere, 84.14 g of dimer acid, 30.64 g of decanediamine, and 0.0574 g of hypophosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 50 °C and held at that temperature for 2 h for pre-reaction. Subsequently, the temperature was raised to 200 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 1 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 1 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 65420 g / mol.

[0052] Example 3:

[0053] Under an inert atmosphere, 84.14 g of dimer acid, 31.55 g of decanediamine, and 0.2314 g of sulfurous acid were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 90 °C and held at that temperature for 4 h for pre-reaction. Subsequently, the temperature was raised to 260 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 4 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 24 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 118570 g / mol.

[0054] Example 4:

[0055] Under an inert atmosphere, 84.14 g of dimer acid, 31.25 g of decanediamine, and 0.1154 g of phosphate ester were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 70 °C and held at that temperature for 3 h for pre-reaction. Subsequently, the temperature was increased to 240 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 2 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 12 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 98730 g / mol.

[0056] Example 5:

[0057] Under an inert atmosphere, 84.14 g of dimer acid, 30.94 g of decanediamine, and 0.2302 g of phosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 60 °C and held at that temperature for 3 h for pre-reaction. Subsequently, the temperature was increased to 260 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 3 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 16 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 97680 g / mol.

[0058] Example 6:

[0059] Under an inert atmosphere, 84.14 g of hydrogenated dimer acid, 30.94 g of decanediamine, and 0.1151 g of sodium hypophosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 60 °C and held at that temperature for 1 h for pre-reaction. Subsequently, the temperature was increased to 240 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 2 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 6 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 123650 g / mol.

[0060] Example 7:

[0061] Under an inert atmosphere, 84.14 g of hydrogenated dimer acid, 31.55 g of decanediamine, and 0.2314 g of phenyl phosphate were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 90 °C and held at that temperature for 4 h for pre-reaction. Subsequently, the temperature was increased to 280 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 4 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 24 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 148,750 g / mol.

[0062] Example 8:

[0063] Under an inert atmosphere, 84.14 g of hydrogenated dimeric acid, 31.25 g of decanediamine, and 0.0923 g of sodium hypophosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 80 °C and held at that temperature for 3 h for pre-reaction. Subsequently, the temperature was increased to 270 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 3 h. Afterward, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 18 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 135830 g / mol.

[0064] Example 9:

[0065] Under an inert atmosphere, 84.14 g of hydrogenated dimer acid, 30.64 g of decanediamine, and 0.0574 g of triphenyl phosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 50 °C and held at that temperature for 1 h for pre-reaction. Subsequently, the temperature was raised to 200 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 1 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 1 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 86750 g / mol.

[0066] Example 10:

[0067] Under an inert atmosphere, 84.14 g of hydrogenated dimer acid, 30.94 g of decanediamine, and 0.1151 g of phosphite were added to a high-pressure reactor and sealed. After purging with nitrogen, the reaction system was heated to 90 °C and held at that temperature for 2 h for pre-reaction. Subsequently, the temperature was increased to 230 °C for polycondensation reaction, and the system pressure was maintained at 1.7 MPa for 3 h. Then, the pressure was gradually reduced to restore the system to atmospheric pressure, and the reaction was continued under negative pressure with stirring for 2 h. After the reaction was completed, the product was cooled in cooling water, washed three times with anhydrous ethanol, and dried at 35 °C for 12 h to obtain polyamide with a number-average molecular weight of 84380 g / mol.

[0068] Example 11:

[0069] The thermal, mechanical, and optical properties of the polyamides obtained in Examples 1-10 were tested using DSC, TGA, an electronic universal testing machine, and a WGT-B transmittance and haze meter. The test results are shown in Table 1. The results indicate that the long-chain polyamides prepared in this invention have a low melting point, excellent thermal stability, good mechanical properties, and high transmittance.

[0070] Table 1. Physicochemical parameters of polyamides prepared in Examples 1-10

[0071]

[0072]

[0073] Example 12:

[0074] Cyclic tensile tests were conducted on the polyamides obtained in Examples 1-10. Tensile-recovery cycles were performed under strain conditions of 50%, 100%, 150%, and 200%, and the elastic recovery rate was calculated. Specific test results are shown in Table 2. The results indicate that the long-chain polyamides prepared in this invention still exhibit good elastic recovery performance and cyclic stability under high strain conditions.

[0075] Table 2 Elastic recovery rates of polyamides prepared in Examples 1-10 under strains ranging from 50% to 200%.

[0076]

[0077] Example 13:

[0078] The mechanical properties of the polyamides obtained in Examples 1-10 under different low-temperature conditions were evaluated by low-temperature tensile testing. Specific test results are shown in Tables 3 and 4. The results indicate that the long-chain polyamides prepared in this invention maintain high tensile strength and elongation at break under low-temperature conditions, exhibiting excellent low-temperature resistance.

[0079] Table 3. Low-temperature tensile strength parameters of polyamides prepared in Examples 1-10

[0080]

[0081]

[0082] Table 4. Low-temperature elongation at break parameters of polyamides prepared in Examples 1-10

[0083]

[0084]

[0085] Example 14:

[0086] Chemical depolymerization and recovery experiments were conducted on the polyamides prepared in Examples 1-10, and the monomer recovery rate was determined. The specific test results are shown in Table 5. The results show that the long-chain polyamides prepared in this invention can efficiently recover monomers through chemical methods, with a high monomer recovery rate, demonstrating good recyclability.

[0087] Table 5. Monomer recovery rates of polyamides prepared in Examples 1-10 after chemical recovery.

[0088]

[0089] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A bio-based long-chain polyamide and its preparation method, characterized in that, The polymer is any one of the structures shown in formulas Ia, Ib, Ic, Id, Ie, and If; Where m is selected from any integer between 10 and 500.

2. The bio-based long-chain polyamide of claim 1 and its preparation method, characterized in that: Under an inert atmosphere, dimer acid or hydrogenated dimer acid, decanediamine, and a catalyst are added to a high-pressure reactor for polycondensation. The reaction is first heated to temperature T1 and maintained for time B1 to complete the pre-reaction process, and then further heated to temperature T2 to continue the reaction. When the system pressure reaches 1.7 MPa, the pressure is maintained for time B2. Then, the pressure is gradually reduced to atmospheric pressure, and the reaction is further carried out under negative pressure with vacuum and stirring for time B3 to promote the polycondensation reaction. After the reaction is completed, the product is placed in deionized water and cooled to obtain the target polyamide.

3. The method according to claim 2, characterized in that, The dimer acid is a dimer acid and a hydrogenated dimer acid.

4. The method according to claim 2, characterized in that, The molar ratio of the dimeric acid to the decanediamine is 1:(1.01 to 1.04).

5. The method according to claim 2, characterized in that, The catalyst is sodium hypophosphite, hypophosphite, sulfurous acid, phosphate ester, phosphite ester, phenyl phosphate ester, or triphenyl phosphite ester, preferably sodium hypophosphite, and the catalyst accounts for 0.01 wt% to 5 wt% of the total weight.

6. The method according to claim 2, characterized in that, The temperature for A1 is 50–90℃, the reaction time for B1 is 1–4 h, the temperature for A2 is 200–280℃, the reaction time for B2 is 1–4 h, and the reaction time for B3 is 1–12 h.

7. The method according to claim 2, characterized in that, Melting point: 70–90℃; maximum thermal decomposition temperature: 440–480℃; tensile strength: 10–35 MPa; elongation at break: 500–1500%; toughness: 50–200 MJ / m. 3 It has a light transmittance of 80-95%, a haze of 9-13%, and an elastic recovery rate of ≥90%.

8. The method according to claim 2, characterized in that, Application of the long-chain polyamide in low-temperature resistant materials.

9. The method according to claim 2, characterized in that, The application of the long-chain polyamide in chemically recyclable materials.

10. The use of the method described in claim 1 or 2 in the preparation of long-chain polyamides.

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