A bio-based polyamide hot melt adhesive and a method of making the same

Abstract

The application belongs to the field of hot melt adhesive materials, and discloses a bio-based polyamide hot melt adhesive and a preparation method thereof. The method uses dimer acid or hydrogenated dimer acid and pentanediamine as main raw materials to prepare bio-based polyamide through polycondensation reaction under the protection of inert gas, and obtains polyamide hot melt adhesives with different molecular weights by adjusting the reaction temperature, reaction time, catalyst type and acid-amine ratio. The obtained bio-based polyamide has low melting temperature, high shear strength and high elongation at break, and exhibits good flexibility and bonding performance. At the same time, the material can still maintain high shear strength in a low-temperature environment, and has excellent low-temperature resistance. In addition, the bio-based polyamide hot melt adhesive can be physically recycled through melt reprocessing, and the monomers can also be recycled through chemical depolymerization, realizing the recycling of the material. The preparation method is simple, the raw materials are widely sourced, and the obtained material has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hot melt adhesives, and specifically relates to a bio-based polyamide hot melt adhesive and its preparation method. Background Technology

[0002] Traditional polyamide hot melt adhesives are typically formed by the condensation polymerization of diacids (such as adipic acid and sebacic acid) and diamines (such as ethylenediamine and hexamethylenediamine). Their regular molecular chains enable strong intermolecular hydrogen bonding, resulting in high melting points and good adhesive strength. However, this structure also presents limitations: the high melting temperature and melt viscosity demand sophisticated application processes, and the material exhibits poor flexibility, making it prone to embrittlement at low temperatures. Furthermore, small-molecule plasticizers introduced to improve flexibility are prone to migration or volatilization during use, affecting the adhesive's stability. Additionally, the recycling of traditional polyamide hot melt adhesives after use remains challenging, hindering material recycling.

[0003] Dimer acids are mixtures of dicarboxylic acids containing 36 carbon atoms, synthesized from unsaturated vegetable oil fatty acids (such as oleic acid and linoleic acid) through reactions such as the Diels-Alder reaction. Their molecular structure features long aliphatic carbon chains with cyclic or branched structures in the middle of the chains. This structure improves the flexibility of the polymer molecular chain and reduces crystallinity. Therefore, polyamides synthesized using dimer acids as monomers typically exhibit low melting points, good flexibility, and good low-temperature resistance, showing promising application prospects in the field of hot melt adhesives.

[0004] This invention uses dimer acid and pentanediamine as main raw materials to synthesize the target polyamide resin through a one-step polycondensation reaction. The bio-based polyamide prepared by this method has a low melting point, good flexibility, and excellent low-temperature resistance. Furthermore, the material can be recycled through physical recovery and chemical depolymerization, and can be used as a hot melt adhesive without complex blending modification or a large number of additives. Thus, it overcomes the problems of insufficient flexibility and low-temperature embrittlement of traditional polyamide hot melt adhesives while maintaining high shear strength. Summary of the Invention

[0005] Purpose of the invention: The problem to be solved by the present invention is to address the shortcomings of existing polyamide hot melt adhesives by providing a bio-based polyamide hot melt adhesive 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 bio-based polyamide hot melt adhesive with a structure as shown in formulas Ia, Ib, Ic, Id, Ie and If.

[0008]

[0009]

[0010] The polymer is any one of the structures shown in formulas Ia, Ib, Ic, Id, Ie, and If;

[0011] This invention introduces a long carbon chain structure from a dimer acid, giving the polymer molecular chain high flexibility, thereby endowing the material with excellent flexibility and good low-temperature mechanical properties. Simultaneously, this structure reduces the crystallinity of the material, resulting in a polyamide with a lower melting temperature and good processability, making it suitable for the hot melt adhesive field.

[0012] Secondly, the present invention provides a method for preparing the bio-based polyamide hot melt adhesive.

[0013] In this process, under inert gas protection, dimer acid or hydrogenated dimer acid, pentanediamine, and catalyst are added to a high-pressure reactor. The reactor temperature is first raised to temperature T1, and the reaction ends after time B1. Then, the temperature is raised to T2 to continue the reaction. When the pressure reaches 1.7 MPa and is maintained for time B2, the pressure is gradually reduced to atmospheric pressure. Finally, a vacuum is drawn and the reaction is stirred for time B3. After the reaction is completed, the mixture is cooled in deionized water to obtain bio-based polyamide. The processing temperature of the bio-based polyamide hot melt adhesive is T3, and the processing time is B4.

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

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

[0016] The catalyst is sodium hypophosphite, sodium acetate, calcium acetate, zinc acetate, lithium chloride, triethylamine, tetrabutyl titanate, and antimony trioxide, preferably sodium hypophosphite, and the amount of the catalyst is 0.01 wt% to 5 wt% of the total weight of the reaction system.

[0017] The reaction temperatures for T1 are 50–90℃, and the reaction time for B1 is 1–4 h; for T2, the temperature is 200–260℃, and the reaction time for B2 is 1–4 h; for B3, the reaction time is 1–12 h. The processing temperature range for bio-based polyamide hot melt adhesive is 80–120℃, and the processing time range is 10–60 min.

[0018] Thirdly, through the above-mentioned structural design and control of polymerization process conditions, the bio-based polyamide hot melt adhesive prepared by this invention has excellent comprehensive performance.

[0019] The hot melt adhesive of the bio-based polyamide has a melting point of 60-70℃, a maximum thermal decomposition temperature of 410-460℃, a tensile strength of 10-25MPa, an elongation at break of 300-1000%, and a shear strength range of 6-18MPa.

[0020] The introduction of long carbon chain structures in dimer acids gives the polymer molecular chains high flexibility, thus endowing the material with excellent flexibility. At the same time, the amide groups in the polyamide molecular chains can form hydrogen bonds with the substrate surface, improving interfacial interaction forces and thus giving the material good adhesion properties, enabling it to better adapt to the deformation requirements of the substrate during hot melt adhesive applications.

[0021] The lower melting temperature allows the material to be applied at lower processing temperatures, thereby reducing processing energy consumption and expanding its application in heat-sensitive materials.

[0022] Fourthly, the bio-based polyamide hot melt adhesive prepared by this invention has excellent low-temperature resistance.

[0023] In particular, the bio-based polyamide hot melt adhesive can still maintain good bonding performance and structural stability under low temperature conditions.

[0024] The bio-based polyamide hot melt adhesive can maintain a high shear strength within a temperature range of 25°C to -70°C, specifically 95% to 115% of the shear strength at room temperature, which is 6 to 19 MPa.

[0025] Under low-temperature shear test conditions, the bio-based polyamide hot melt adhesive is not prone to embrittlement or adhesive failure, thus exhibiting excellent low-temperature resistance and being suitable for bonding applications in low-temperature environments.

[0026] Fifthly, the bio-based polyamide hot melt adhesive prepared by this invention has good recyclability.

[0027] The bio-based polyamide hot melt adhesive can be physically recycled through a melt reprocessing method, which involves heating the recycled hot melt adhesive material to a molten state and reshaping it while still maintaining good adhesive properties.

[0028] The bio-based polyamide hot melt adhesive can also be depolymerized and recycled through chemical methods. Under acidic conditions, heating the polyamide can cause a depolymerization reaction, which degrades the polymer into dimer acid or hydrogenated dimer acid monomers and pentanediamine monomers. The recovery rate of dimer acid or hydrogenated dimer acid is 90% to 99%, and the recovery rate of pentanediamine is 85% to 90%.

[0029] The monomers can be recovered through solvent extraction and separation, and can be reused in the polymerization reaction, thereby realizing the recycling of the bio-based polyamide hot melt adhesive material.

[0030] Beneficial effects:

[0031] (1) This invention provides a bio-based polyamide hot melt adhesive. By introducing a long carbon chain structure of dimer acid, the polymer molecular chain has high flexibility, thereby endowing the material with good flexibility and adhesion properties. The prepared polyamide hot melt adhesive has a low melting temperature and good processing performance, while also having high shear strength, enabling it to achieve stable bonding under low processing temperature conditions, and is suitable for hot melt adhesive applications on various substrates.

[0032] (2) The bio-based polyamide hot melt adhesive prepared by the present invention has excellent low temperature resistance. It can still maintain high shear strength and good adhesion under low temperature conditions, and can still maintain stable adhesion in the temperature range of 25℃ to -70℃, thereby expanding its application range in low temperature environments.

[0033] (3) The bio-based polyamide hot melt adhesive prepared by the present invention has good recyclability. It can be physically recycled through melt reprocessing, and dimer acid or hydrogenated dimer acid and pentanediamine monomer can be recycled through chemical depolymerization, thereby realizing the recycling of materials, improving resource utilization efficiency and reducing environmental burden. Attached Figure Description

[0034] 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.

[0035] Figure 1 The polyamide product of Example 1 1 HNMR spectrum;

[0036] Figure 2 The TGA image of the polyamide product from Example 1 is shown.

[0037] Figure 3 The DSC diagram of the polyamide product in Example 1 is shown below.

[0038] Figure 4 This is a GPC diagram of the polyamide product from Example 1.

[0039] Figure 5 The graph shows the mechanical properties of the polyamide product from Example 1. Detailed Implementation

[0040] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0041] 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.

[0042] The molecular weight of the samples was determined by a WTRFX-11 gel permeation chromatography (GPC) system with tetrahydrofuran (THF) as the mobile phase and a flow rate of 0.7 mL / min.

[0043] 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 the sample was tested under nitrogen protection at a heating rate of 20 °C / min, with a test temperature range of 30–800 °C.

[0044] The melting temperature of the sample 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 procedure consisted of heating, cooling, and then heating 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 temperature 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.

[0045] The mechanical properties of the samples were tested using an electronic universal testing machine. The tensile properties were tested according to the national standard GB / T1040.1-2006, with a tensile rate of 50 mm / min and a test temperature of room temperature. The shear properties were tested according to the ASTM D1002-10 standard, with a test rate of 50 mm / min.

[0046] The method for testing the low-temperature shear properties of the samples is as follows: The samples are placed in a cold trap, immersed for 1 hour under different low-temperature conditions, and then taken out and tested on an electronic universal testing machine at a test 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. -1 The reaction was carried out in a hydrochloric acid solution at 160°C for 10 hours. After cooling to room temperature, the dimer acid precipitated and was extracted three times with dichloromethane. 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 diamine monomer, which was then extracted three times with dichloromethane and recovered by rotary evaporation.

[0048] Example 1:

[0049] 84.14 g of dimer acid, 15.63 g of pentamethylenediamine, and 0.0998 g of sodium hypophosphite were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 60°C and held at this temperature for 1 hour. The temperature was then increased to 240°C, and the pressure was maintained at 1.7 MPa for 2 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 6 hours.

[0050] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then placed in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 15560 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 100°C for 40 minutes.

[0051] Example 2:

[0052] 84.14 g of dimer acid, 15.48 g of pentamethylenediamine, and 0.0493 g of sodium acetate were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 50°C and held at this temperature for 2 hours. The temperature was then increased to 200°C, and the pressure was maintained at 1.7 MPa for 1 hour. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created to allow the reactor to be stirred under negative pressure for 1 hour.

[0053] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then placed in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 8540 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 80°C for 50 minutes.

[0054] Example 3:

[0055] 84.14 g of dimer acid, 15.94 g of pentamethylenediamine, and 0.2001 g of calcium acetate were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 90°C and held at this temperature for 4 hours. The temperature was then increased to 260°C, and the pressure was maintained at 1.7 MPa for 4 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 12 hours.

[0056] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then dried in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 21570 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 120°C for 60 minutes.

[0057] Example 4:

[0058] 84.14 g of dimer acid, 15.78 g of pentamethylenediamine, and 0.0992 g of zinc acetate were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 70°C and held at this temperature for 3 hours. The temperature was then increased to 240°C, and the pressure was maintained at 1.7 MPa for 2 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 8 hours.

[0059] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then dried in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 18730 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 90°C for 10 minutes.

[0060] Example 5:

[0061] 84.14 g of dimer acid, 15.63 g of pentanediamine, and 0.1995 g of lithium chloride were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 60°C and held at this temperature for 3 hours. The temperature was then increased to 260°C, and the pressure was maintained at 1.7 MPa for 3 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 9 hours.

[0062] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then placed in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 18840 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 80°C for 20 minutes.

[0063] Example 6:

[0064] 84.14 g of hydrogenated dimeric acid, 15.63 g of pentamethylenediamine, and 0.0998 g of sodium hypophosphite were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 60°C and held at this temperature for 1 hour. The temperature was then increased to 240°C, and the pressure was maintained at 1.7 MPa for 2 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 6 hours.

[0065] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then placed in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 23650 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 100°C for 40 minutes.

[0066] Example 7:

[0067] 84.14 g of hydrogenated dimeric acid, 15.94 g of pentanediamine, and 0.2001 g of triethylamine were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 90°C and held at this temperature for 4 hours. The temperature was then increased to 260°C, and the pressure was maintained at 1.7 MPa for 4 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 12 hours.

[0068] After polycondensation, stirring was stopped, and the polymer product was drained into cooling water. It was washed three times with anhydrous ethanol and then placed in a 35°C oven for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 28750 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 110°C for 30 minutes.

[0069] Example 8:

[0070] 84.14 g of hydrogenated dimeric acid, 15.78 g of pentanediamine, and 0.0799 g of tetrabutyl titanate were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 80°C and held at this temperature for 3 hours. The temperature was then increased to 220°C, and the pressure was maintained at 1.7 MPa for 3 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 8 hours.

[0071] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then dried in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 25830 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 90°C for 50 minutes.

[0072] Example 9:

[0073] 84.14 g of hydrogenated dimeric acid, 15.48 g of pentanediamine, and 0.0498 g of antimony trioxide were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 50°C and held at this temperature for 1 hour. The temperature was then increased to 200°C, and the pressure was maintained at 1.7 MPa for 1 hour. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created to allow the reactor to be stirred under negative pressure for 1 hour.

[0074] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then placed in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 11320 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 80°C for 60 minutes.

[0075] Example 10:

[0076] 84.14 g of hydrogenated dimeric acid, 15.63 g of pentanediamine, and 0.0998 g of antimony trioxide were sequentially added to a high-pressure reactor, which was then sealed. After purging with nitrogen at room temperature, the reactor was heated to 90°C and held at this temperature for 2 hours. The temperature was then increased to 230°C, and the pressure was maintained at 1.7 MPa for 3 hours. The pressure was then gradually released to atmospheric pressure, and finally, a vacuum was created, allowing the reactor to be stirred under negative pressure for 7 hours.

[0077] After polycondensation, stirring was stopped, the polymer product was drained into cooling water, washed three times with anhydrous ethanol, and then dried in an oven at 35°C for 12 hours to obtain bio-based polyamide with a number-average molecular weight of 24380 g / mol. The processing conditions for the prepared bio-based polyamide hot melt adhesive were: heating at 120°C for 10 minutes.

[0078] Example 11:

[0079] The melting point, thermal decomposition temperature, tensile strength, elongation at break, and shear strength of the polyamides obtained in Examples 1-10 were tested using DSC, TGA, and an electronic universal testing machine. The specific test results are shown in Table 1. The results indicate that the bio-based polyamide prepared in this invention has a low melting temperature and good thermal stability, while also exhibiting high shear strength and high elongation at break, indicating that the material possesses good adhesive properties and excellent flexibility, making it suitable for hot melt adhesive applications.

[0080] Table 1. Physicochemical parameters of polyamide hot melt adhesives prepared in Examples 1-10

[0081]

[0082] Example 12:

[0083] The shear properties of the polyamide hot melt adhesives obtained in Examples 1-10 under different low-temperature conditions were evaluated by low-temperature shear tests. The specific test results are shown in Table 2. The results show that the bio-based polyamide hot melt adhesive prepared in this invention maintains high shear strength under low-temperature conditions, exhibiting excellent low-temperature resistance.

[0084] Table 2. Test results of shear properties of polyamide hot melt adhesives prepared in Examples 1-10 at different temperatures.

[0085]

[0086] Example 13:

[0087] The physical recycling performance of the polyamide hot melt adhesives obtained in Examples 1-10 was evaluated through multiple melt-reprocessing recycling tests. Specific test results are shown in Table 3. The results indicate that the bio-based polyamide prepared in this invention maintains high shear strength after multiple recycling cycles, demonstrating good physical recycling performance.

[0088] Table 3. Shear performance test results of polyamides prepared in Examples 1-10 after physical recycling.

[0089]

[0090]

[0091] Example 14:

[0092] The monomer recovery performance of the polyamides obtained in Examples 1-10 was evaluated by chemical depolymerization and recovery tests, and the specific test results are shown in Table 4. The results show that the bio-based polyamides prepared in this invention can achieve effective depolymerization under acidic conditions, and the dimer acid (or hydrogenated dimer acid) and pentanediamine monomers have high recovery rates, demonstrating good chemical recovery performance.

[0093] Table 4. Monomer recovery rates of polyamides prepared in Examples 1-10 after chemical recovery.

[0094]

[0095] 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 polyamide hot melt adhesive, 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 method for preparing the bio-based polyamide according to claim 1, characterized in that: Under inert gas protection, dimer acid or hydrogenated dimer acid, pentanediamine and catalyst are added to a high-pressure reactor. The reactor temperature is first raised to temperature T1 and stopped after time B1. Then the temperature is raised to T2 to continue the reaction. When the pressure reaches 1.7 MPa and is held for time B2, the pressure is gradually released to atmospheric pressure. Finally, a vacuum is drawn and the reaction is stirred for time B3. After the reaction is completed, the mixture is cooled in deionized water to obtain bio-based polyamide. The processing temperature of the bio-based polyamide hot melt adhesive is T3 and the processing time is B4.

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

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

5. The method according to claim 2, characterized in that, The catalyst is sodium hypophosphite, sodium acetate, calcium acetate, zinc acetate, lithium chloride, triethylamine, tetrabutyl titanate, and antimony trioxide, preferably sodium hypophosphite, and the amount of the catalyst is 0.01 wt% to 5 wt% of the total weight of the reaction system.

6. The method according to claim 2, characterized in that, The T1 temperature is 50–90℃, the B1 reaction time is 1–4 h, the T2 temperature is 200–260℃, the B2 reaction time is 1–4 h, and the B3 reaction time is 1–12 h. The processing temperature range for bio-based polyamide hot melt adhesive is 80–120℃, and the processing time range is 10–60 min.

7. The method according to claim 2, characterized in that, The hot melt adhesive of the bio-based polyamide has a melting point of 60-70℃, a maximum thermal decomposition temperature of 410-460℃, a tensile strength of 10-25MPa, an elongation at break of 300-1000%, and a shear strength range of 6-18MPa.

8. The method according to claim 2, characterized in that, Application of the bio-based polyamide hot melt adhesive in low-temperature resistant adhesive materials.

9. The method according to claim 2, characterized in that, The application of the bio-based polyamide hot melt adhesive in recyclable materials, wherein the recycling includes physical recycling and chemical recycling.

10. The use of the method described in claim 1 or 2 in the preparation of bio-based polyamide hot melt adhesives.

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