Semi-aromatic nylon and preparation method thereof

Abstract

The invention discloses semi-aromatic nylon and a preparation method thereof, and belongs to the technical field of polyamide materials, the method comprises the following steps: adding calcium carbonate, a coupling agent and polyformaldehyde foam, and mixing to obtain pretreated calcium carbonate; the pretreated calcium carbonate, bio-based 2, 5-bis (aminomethyl) furan, bio-based isophthalic acid and an acid catalyst are mixed for polymerization, and a polymerization melt is obtained; performing post-treatment to obtain semi-aromatic nylon; the nylon prepared by adopting the formula and the method disclosed by the invention has the rigidity of wholly aromatic nylon and the toughness of semi-aromatic nylon, and is mild in synthesis condition and low in energy consumption; the addition of the polyformaldehyde foam can reduce the use amount of the coupling agent, reduce the addition of the auxiliary agent and improve the performance of the nylon material, and the polyformaldehyde foam gasifies and escapes from the system after assisting the uniform dispersion of the calcium carbonate, so that the introduction of the auxiliary agent is further reduced; the nylon can be applied to the fields of automobiles, electronics, ocean engineering or aerospace and the like.

Description

Technical Field

[0001] This application belongs to the technical field of polyamide materials, and in particular relates to a semi-aromatic nylon and a preparation method thereof. Background Art

[0002] The manufacturing temperature of fully aromatic nylon is high, the processing difficulty is great, the fatigue resistance and pressure resistance are insufficient, and melt extrusion and injection molding cannot be achieved; so the current focus is mainly on semi-aromatic nylon. Semi-aromatic nylon is a combination of aliphatic and aromatic groups. Most of the current semi-aromatic nylons have benzene rings as the basic skeleton for the aromatic groups, but the benzene ring skeleton has many disadvantages: 1. The raw materials rely on petrochemical industry, and the carbon emissions in the synthesis process are high; 2. Benzene rings are usually only soluble in concentrated sulfuric acid, which is highly corrosive to equipment; 3. The material has poor toughness and high brittleness, and is prone to delamination or fracture; 4. The transparency is low, etc.

[0003] Bio-based 2,5-bis(aminomethyl)furan, abbreviated as BAMF, is a nitrogen-containing furan derivative synthesized based on biomass resources. As a high-performance polyamide monomer, it has the potential to replace traditional petroleum-based monomers; the raw materials of BAMF are 5-hydroxymethylfurfural (HMF) or furfural. HMF is generated by acid-catalyzed dehydration of sugars such as cellulose and hemicellulose, and furfural can be extracted from corncobs and bagasse; Bio-based isophthalic acid is an aromatic dicarboxylic acid synthesized by biological fermentation or chemical catalysis using renewable biomass resources (such as sugars, lignocellulose, etc.) as raw materials. It is a sustainable substitute for traditional petroleum-based isophthalic acid, has the same chemical structure, but has a lower carbon footprint, which conforms to the development trend of green chemistry; Calcium carbonate is an inert material. Applying it in nylon materials can improve the processing performance of the materials, such as increasing the hardness, wear resistance and dimensional stability of nylon, thereby enhancing its service performance; it can reduce the shrinkage rate and moisture absorption of nylon, and improve dimensional stability and heat resistance; although the introduction of calcium carbonate has many benefits, calcium carbonate is prone to uneven mixing and agglomeration during the preparation process, and has poor bonding with nylon materials, and additional treatment agents need to be added for improvement. For example, Patent CN101363143B discloses a nylon 6 / ultrafine calcium carbonate particle composite fiber and a preparation method thereof. It uses stearic acid, titanate coupling agent, etc. as surface treatment agents. The surface treatment agents remaining inside the nylon will affect the performance of the nylon, resulting in poor nylon quality; for example, stearic acid will cause a decrease in tensile strength and poor impact performance, and the titanate coupling agent will compete with the polar groups of nylon in the reaction, resulting in a decrease in coupling efficiency, cross-linking or degradation of the nylon molecular chain, and affecting the melt fluidity. Summary of the Invention

[0004] The purpose of the implementation of this application is to provide a semi-aromatic nylon and its preparation method, so as to solve the technical problems existing in the prior art, such as the difficult processing and poor toughness of fully aromatic nylon, the poor rigidity of semi-aromatic nylon, and the large number of additives introduced in nylon synthesis resulting in performance changes.

[0005] To achieve the above purpose, the technical solution adopted in this application is: to provide a preparation method of semi-aromatic nylon, which specifically includes the following steps: (1). Prepare pretreated calcium carbonate: In a stirring device, add calcium carbonate and a coupling agent and mix them, then add polyoxymethylene foam, raise the temperature and mix. After mixing is completed, pretreated calcium carbonate is obtained; (2). Melt polymerization: Add pretreated calcium carbonate, bio-based 2,5-bis(aminomethyl)furan, bio-based isophthalic acid, and an acidic catalyst into a polymerization kettle, fill it with an inert gas, raise the temperature and pressure to carry out polymerization; after polymerization is completed, continue to raise the temperature and pressure and continue stirring and end capping; then reduce the pressure and raise the temperature to obtain a polymerized melt; (3). Post-treatment: Apply pressure, extrude and granulate the polymerized melt to obtain semi-aromatic nylon.

[0006] In one of the embodiments, In step (1), the coupling agent is one of a titanate coupling agent, an aluminate coupling agent or a phosphate coupling agent, and the mass ratio of calcium carbonate to the coupling agent is 1:0.001 - 0.005.

[0007] In one of the embodiments, In step (1), the particle size of calcium carbonate is 50 - 100 nm, and the mass ratio of calcium carbonate to polyoxymethylene foam is 1:0.2 - 0.4; raise the temperature to 80 °C.

[0008] In one of the embodiments, In step (2), the molar ratio of bio-based 2,5-bis(aminomethyl)furan to bio-based isophthalic acid is 1:1; the pretreated calcium carbonate accounts for 10 - 20 wt% of the total mass of bio-based 2,5-bis(aminomethyl)furan and bio-based isophthalic acid.

[0009] In one of the embodiments, In step (2), the acidic catalyst is phosphoric acid or phosphorous acid, and the mass ratio of bio-based 2,5-bis(aminomethyl)furan to the acidic catalyst is 1:0.002 - 0.01.

[0010] In one of the embodiments, In step (2), the inert gas is nitrogen or argon, and the flow rate of the inert gas is 50 mL / min.

[0011] In one of the embodiments, In step (ii), the polymerization temperature is 200 - 220 °C, and the pressure is increased to 1.5 MPa; after the polymerization is completed, the temperature for continued heating and pressure increase is 240 °C, and the pressure is 1.7 - 2.0 MPa; the temperature for pressure reduction and heating is 270 - 290 °C; preferably, the temperature for pressure reduction and heating is 280 °C.

[0012] In one embodiment, In step (ii), the end-capping agent for end-capping is benzoic acid, and the dosage of the end-capping agent is 0.2 - 0.6 wt% of the polymerized melt.

[0013] The present application also provides a semi-aromatic nylon prepared by the preparation method according to any one of the above embodiments.

[0014] Compared with the prior art, the present application has the following beneficial effects: 1. While 2,5-bis(aminomethyl)furan replaces the benzene ring and contains aliphatic chain segments, the furan ring has the advantages of semi-rigidity, combining strength and toughness. It not only endows the nylon with the rigid characteristics of fully aromatic nylon but also has high toughness of semi-aromatic nylon, can be extrusion-molded, has high melt processability, does not use concentrated acid during processing, has little corrosion to equipment, and has low process cost; the conjugated structure of the furan ring can also provide high thermal stability and low moisture absorption; 2. Both 2,5-bis(aminomethyl)furan and isophthalic acid are bio-based materials, and the raw materials are all converted from renewable biological resources, which are green and environmentally friendly, and are safe and friendly to users and the natural environment; doping with a part of calcium carbonate can further enhance the rigidity and wear resistance of the nylon, comparable to fully aromatic nylon, and can also reduce the use of bio-based raw materials and reduce costs; 3. When treating calcium carbonate, polyoxymethylene foam is added. During the foaming process of the polyoxymethylene foam, the expansion of gas will form bubbles in the melt, and the growth and coalescence of the bubbles will generate local high shear force; this shear force can effectively break the agglomeration of calcium carbonate and make the calcium carbonate more evenly dispersed; the bubbles generated by the polyoxymethylene foam will push the surrounding melt to flow, driving the calcium carbonate to move towards the pore wall or the edge of the pore. This process promotes the directional distribution of calcium carbonate, reduces local enrichment, and this phenomenon can reduce the dosage of the coupling agent, weaken the negative impact of the coupling agent on the nylon material, but can achieve a better dispersion effect, achieving two birds with one stone; 4. The polyoxymethylene foam can be completely gasified at 240 °C. After the present application improves the process to enable the polyoxymethylene foam to play its role, it turns into gas and escapes. During polymerization, first, below the gasification temperature of the polyoxymethylene foam, 2,5-bis(aminomethyl)furan and isophthalic acid form salts, and accompanied by a small amount of gasification of the polyoxymethylene foam, which helps the calcium carbonate to diffuse; after the salt formation is completed, the temperature and pressure are increased, and the polyoxymethylene foam will carry the calcium carbonate to form bubbles, further helping the calcium carbonate to diffuse, and continue to stir until the polyoxymethylene foam turns into gas and is completely discharged from the inside of the nylon material. Detailed implementation manners

[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer and more understandable, this application will be further described in detail. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0016] Example 1 A preparation method of semi-aromatic nylon specifically includes the following steps: (1). Prepare pretreated calcium carbonate: In a stirring device, add 1 kg of calcium carbonate (the particle size of calcium carbonate is 50 - 100 nm) and 0.003 kg of titanate coupling agent and mix for 30 min, then add 0.3 kg of polyformaldehyde foam, heat up to 80 °C and mix for 1 h. After mixing, remove the calcium carbonate that has not been wrapped into the polyformaldehyde foam to obtain pretreated calcium carbonate (calcium carbonate loading rate 95%). The remaining unused pretreated calcium carbonate can be reserved for later use; (2). Melt polycondensation: Transfer 0.46 kg of pretreated calcium carbonate into a polymerization kettle, add 1.4 kg of bio-based 2,5-bis(aminomethyl)furan, 1.66 kg of bio-based isophthalic acid, and 0.84 kg of phosphoric acid. Charge nitrogen at a flow rate of 50 mL / min, heat up to 210 °C, increase the pressure to 1.5 MPa and carry out polymerization for 3 h; After the polymerization is completed, gradually discharge the gas, heat up to 240 °C again, increase the pressure to 1.8 MPa, keep the rotation speed in the kettle at 200 - 300 rpm, stir for 3 h, and end-cap with 0.2 wt% of benzoic acid; Slowly reduce the pressure of the polymerization kettle to 0, heat up to 280 °C again, and continue to react for 1 h; Stop stirring to obtain a polymer melt; (3). Post-treatment: Apply pressure and extrude and pelletize the polymer melt to obtain semi-aromatic nylon PA-FI-1.

[0017] Example 2 The difference between this example and Example 1 is that the coupling agent is aluminate coupling agent, and the mass ratio of calcium carbonate to aluminate coupling agent is 1:0.001. The rest of the operations are the same, and semi-aromatic nylon PA-FI-2 is obtained.

[0018] Example 3 The difference between this example and Example 1 is that the coupling agent is phosphate coupling agent, and the mass ratio of calcium carbonate to aluminate coupling agent is 1:0.005. The rest of the operations are the same, and semi-aromatic nylon PA-FI-3 is obtained.

[0019] Example 4 The difference between this example and Example 1 is that the mass ratio of calcium carbonate to polyoxymethylene foam is 1:0.2, and the rest of the operations are the same, obtaining semi-aromatic nylon PA-FI-4.

[0020] Example 5 The difference between this example and Example 1 is that the mass ratio of calcium carbonate to polyoxymethylene foam is 1:0.4, and the rest of the operations are the same, obtaining semi-aromatic nylon PA-FI-5.

[0021] Example 6 The difference between this example and Example 1 is that the pretreated calcium carbonate accounts for 10 wt% of the total mass of bio-based 2,5-bis(aminomethyl)furan and bio-based isophthalic acid, obtaining semi-aromatic nylon PA-FI-6.

[0022] Example 7 The difference between this example and Example 1 is that the pretreated calcium carbonate accounts for 20 wt% of the total mass of bio-based 2,5-bis(aminomethyl)furan and bio-based isophthalic acid, obtaining semi-aromatic nylon PA-FI-7.

[0023] Example 8 The difference between this example and Example 1 is that the acidic catalyst is phosphorous acid, and the mass ratio of bio-based 2,5-bis(aminomethyl)furan to phosphorous acid is 1:0.002, obtaining semi-aromatic nylon PA-FI-8.

[0024] Example 9 The difference between this example and Example 1 is that the mass ratio of bio-based 2,5-bis(aminomethyl)furan to phosphorous acid is 1:0.01, obtaining semi-aromatic nylon PA-FI-9.

[0025] Example 10 The difference between this example and Example 1 is that the mass ratio of bio-based 2,5-bis(aminomethyl)furan to phosphorous acid is 1:0.008, obtaining semi-aromatic nylon PA-FI-10.

[0026] Example 11 The difference between this example and Example 1 is that end-capping is carried out with 0.6 wt% of benzoic acid, obtaining semi-aromatic nylon PA-FI-11.

[0027] Comparative Example 1 Adding unmodified calcium carbonate (I). In a stirring device, 1 kg of calcium carbonate (the particle size of calcium carbonate is 50 - 100 nm) and 0.2 kg of titanate coupling agent are added and mixed for 30 min, then heated to 140 °C and mixed for 1 h. After mixing, pretreated calcium carbonate is obtained; (2) 0.46 kg of pretreated calcium carbonate, 1.4 kg of bio-based 2,5-bis(aminomethyl)furan, 1.66 kg of bio-based isophthalic acid, and 0.84 kg of phosphoric acid were added to a polymerization kettle. Nitrogen was charged at a flow rate of 50 mL / min, the temperature was raised to 290 °C, the pressure was increased to 2.0 MPa, and a polycondensation reaction was carried out for 10 h to obtain a polymerization melt; it was pressurized, extruded, formed, and pelletized to obtain semi-aromatic nylon PA-FI-1#.

[0028] Experimental Example The PA prepared in Examples 1-10 and Comparative Example 1 was tested for tensile strength, flexural strength, hardness, and yield. Table 1 shows the test items and methods for each item, and Table 2 shows the experimental data for each item.

[0029] Table 1 Experimental Test Items and Methods

[0030] Table 2 Experimental Data

[0031] In Comparative Example 1, without adding polyformaldehyde foam, the usage amount of the coupling agent increased significantly, and the mixing effect of calcium carbonate was poor, with calcium carbonate agglomeration, resulting in poor performance of the nylon material; the nylon prepared by the formula and method of the present application has both the rigidity of fully aromatic nylon and the toughness of semi-aromatic nylon, and the synthesis conditions are mild and the energy consumption is low; the addition of polyformaldehyde foam can reduce the usage amount of the coupling agent, reduce the addition of additives, improve the performance of the nylon material, and the polyformaldehyde foam gasifies and escapes from the system after assisting the uniform dispersion of calcium carbonate, further reducing the introduction of additives; this nylon can be applied to fields such as the automotive field, electronic appliances, marine engineering, or aerospace.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0033] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A preparation method of semi-aromatic nylon, characterized in that Specifically, it includes the following steps: (1) Prepare pretreated calcium carbonate: In a stirring device, add calcium carbonate and a coupling agent and mix them, then add polyformaldehyde foam, raise the temperature and mix. After mixing is completed, pretreated calcium carbonate is obtained; (2) Melt polymerization: Add the pretreated calcium carbonate, bio-based 2,5-bis(aminomethyl)furan, bio-based isophthalic acid, and an acidic catalyst into a polymerization kettle, fill it with an inert gas, raise the temperature and pressure for polymerization; after the polymerization ends, continue to raise the temperature and pressure and continue stirring and end-capping; then reduce the pressure and raise the temperature to obtain a polymer melt; (3) Post-treatment: Apply pressure and extrude and pelletize the polymer melt to obtain semi-aromatic nylon.

2. The preparation method of a semi-aromatic nylon according to claim 1, wherein In step (1), the coupling agent is one of a titanate coupling agent, an aluminate coupling agent, or a phosphate coupling agent, and the mass ratio of the calcium carbonate to the coupling agent is 1:0.001-0.

005.

3. The preparation method of a semi-aromatic nylon according to claim 1, characterized in that, In step (1), the particle size of the calcium carbonate is 50-100 nm, and the mass ratio of the calcium carbonate to the polyformaldehyde foam is 1:0.2-0.4; raise the temperature to 80 °C.

4. The preparation method of a semi-aromatic nylon according to claim 1, characterized in that In step (2), the molar ratio of the bio-based 2,5-bis(aminomethyl)furan to the bio-based isophthalic acid is 1:1; the pretreated calcium carbonate accounts for 10-20 wt% of the total mass of the bio-based 2,5-bis(aminomethyl)furan and the bio-based isophthalic acid.

5. The preparation method of a semi-aromatic nylon according to claim 1, wherein, In step (2), the acidic catalyst is phosphoric acid or phosphorous acid, and the mass ratio of the bio-based 2,5-bis(aminomethyl)furan to the acidic catalyst is 1:0.002-0.

01.

6. The preparation method of a semi-aromatic nylon according to claim 1, characterized in that, In step (2), the inert gas is nitrogen or argon, and the flow rate of the inert gas is 50 mL / min.

7. The preparation method of a semi-aromatic nylon according to claim 1, characterized in that In step (2), the temperature of the polymerization is 200-220 °C, and the pressure is raised to 1.5 Mpa; the temperature for continuing to raise the temperature and pressure after the polymerization ends is 240 °C, and the pressure is 1.7-2.0 Mpa; the temperature for reducing the pressure and raising the temperature is 270-290 °C.

8. A method for preparing a semi-aromatic nylon according to claim 1, characterized in that, In step (2), the end-capping agent for end-capping is benzoic acid, and the dosage of the end-capping agent is 0.2-0.6 wt% of the polymer melt.

9. A semi-aromatic nylon, characterized in that, It is prepared by using the preparation method described in claims 1-8.

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