Lightweight hydrophobic long carbon chain nylon and preparation method thereof

Abstract

The invention discloses light-weight hydrophobic long-carbon-chain nylon and a preparation method thereof, and belongs to the technical field of polyamide materials.The method comprises the following steps that aliphatic dibasic acid, hexamethylenediamine, water, bio-based nanofiller and acrylic acid derivatives are mixed in a stirring device, pH is adjusted, and a mixed material is prepared; pressing the mixed material into a polymerization kettle, adding p-methylstyrene, mixing, filling inert gas, exhausting air, raising the temperature and pressure, slowly reducing the pressure, and carrying out polymerization reaction, so as to prepare a polymer material; and extruding, molding and pelletizing the polymer material to obtain the light-weight hydrophobic long-carbon-chain nylon. The nylon material prepared by the method is good in mechanical property, simple in preparation process, less in chemical residue and green and environment-friendly, and the nylon has double properties of light weight and hydrophobicity and 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 particularly relates to a lightweight hydrophobic long-chain carbon nylon and a preparation method thereof. Background Art

[0002] Materials applied in the fields of automotive, electronic and electrical appliances, ocean engineering or aerospace need to meet the requirement of being lightweight, so as to reduce the weight of products and obtain better performance; moreover, when applied in the above fields, they are mostly used in precision electronic equipment. Traditional long-chain carbon nylons contain a large number of polar amide bonds and are easy to absorb water, resulting in a decrease in dimensional stability and mechanical properties, which limits their application in high-demand working environments; traditional hydrophobic modification technologies mostly adopt copolymerization modification (introducing fluorine-containing monomers or siloxanes), surface treatment (plasma coating, chemical vapor deposition), etc. The processes are complex, the technical costs are high, and the hydrophobic effect is poor; lightweight hydrophobic long-chain carbon nylon is a high-performance polyamide material combining low density, high hydrophobicity and long-chain carbon structure. Currently, most nylons have single functions and do not have the above functions simultaneously, which restricts the development of nylon in the fields of automotive, electronic and electrical appliances, ocean engineering or aerospace.

[0003] CN119613737A discloses a hydrophobic nylon elastomer and a preparation method thereof. By introducing hydrophobic multi-armed epoxy vegetable oil, the water absorption rate of the material can be effectively reduced; CN115160777A discloses a dimensionally stable super wear-resistant hydrophobic nylon composite material and a preparation method thereof. By adding ultra-high molecular weight polyethylene as a hydrophobic agent, with the increase of the content of ultra-high molecular weight polyethylene, the mechanical properties of the composite material decrease greatly, and the fluidity of the composite material is greatly affected; both of the above two patents use ultra-high molecular weight materials as hydrophobic agents, which will cause changes in the properties of nylon, and may also require additional addition of molecular weight regulators and end-capping agents to control the molecular weight of nylon, resulting in a complex production process and higher costs. Summary of the Invention

[0004] The purpose of the implementation of this application is to provide a lightweight hydrophobic long-chain carbon nylon and a preparation method thereof, so as to solve the technical problems that existing hydrophobic nylons mostly use high-molecular mixtures as hydrophobic agents, the preparation process is complex, and the prepared nylons have poor performance and single functions.

[0005] To achieve the above purpose, the technical solution adopted in this application is: to provide a lightweight hydrophobic long-chain carbon nylon and a preparation method thereof, which specifically includes the following steps: (1) Mix aliphatic dibasic acid, hexamethylenediamine, water, bio-based nano-fillers, and acrylic derivatives in a stirring device, adjust the pH to obtain a mixed material; (2) Press the mixed materials into the polymerization kettle, add p-methylstyrene for mixing, fill with inert gas, exhaust air, raise the temperature and pressure, and then slowly reduce the pressure to carry out the polymerization reaction to obtain polymer materials; (3) Extrude and pelletize the polymer materials to obtain lightweight hydrophobic long carbon chain nylon.

[0006] In one embodiment, The aliphatic dibasic acid is one of dodecanedioic acid or sebacic acid. The molar ratio of the aliphatic dibasic acid to hexamethylenediamine is 1:1, and the pH of the mixed materials is 7.3 - 7.8.

[0007] In one embodiment, The bio-based nanofiller is one or two of cellulose nanofibrils, cellulose nanocrystals, and chitin nanofibers; the mass ratio of the bio-based nanofiller to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.1 - 0.3:1. Preferably, the bio-based nanofiller is cellulose nanofibrils, and the mass ratio of the bio-based nanofiller to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.2:1.

[0008] In one embodiment, The acrylic derivative is acrylic acid or methacrylic acid. Preferably, the acrylic derivative is methacrylic acid.

[0009] In one embodiment, The mass ratio of the acrylic derivative to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.06 - 0.1:1, and the mass ratio of p-methylstyrene to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.06 - 0.1:1. Preferably, the mass ratio of the acrylic derivative to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.08:1, and the mass ratio of p-methylstyrene to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.08:1.

[0010] In one embodiment, The inert gas is nitrogen, and the mass ratio of water to the total amount of the aliphatic dibasic acid and hexamethylenediamine is 0.5:1.

[0011] In one embodiment, The temperature of mixing in step (1) is 85 - 95 °C; the mass concentration of the salt formed by the aliphatic dibasic acid and hexamethylenediamine is 50%; In one embodiment, The temperature of the polymerization reaction in step (2) is 200 - 230 °C, and the pressure is 1.5 MPa.

[0012] This application also provides a lightweight hydrophobic long carbon chain nylon, which is prepared by using the preparation method of any one of the above embodiments.

[0013] Compared with the prior art, the present application has the following beneficial effects: 1. By adjusting the ratio of aliphatic dicarboxylic acid to hexamethylenediamine and precisely adjusting the pH to 7.3 - 7.8, the raw materials can be fully polymerized, reducing the escape of excess monomers; the aliphatic dicarboxylic acid and hexamethylenediamine use bio-based raw materials, increasing the bio-based content of nylon and being more environmentally friendly and green; 2. The bio-based nanofiller is a nano-scale reinforcing material prepared from natural biomass. The sources of cellulose nanofibrils and cellulose nanocrystals are wood, straw, or bacterial cellulose. It has a high specific surface area and strength, approaching that of carbon fiber. The nano-structure provides more interfacial bonding sites, significantly enhancing the mechanical properties of the nylon material. The addition of the bio-based nanofiller makes the components disperse more evenly, improves the biocompatibility of each component, and reduces agglomeration, especially suitable for bio-based nylon; adding the bio-based nanofiller to nylon, its nano-structure can reduce the density, making nylon have lightweight properties; 3. The carboxyl group of the acrylic derivative can improve the dispersibility of the components in the aqueous phase, contributing to the polymerization reaction, and enabling the nylon material to maintain mechanical strength while reducing density; 4. The benzene ring and the para-methyl group in the p-methylstyrene structure form a completely non-polar structure, unable to form hydrogen bonds or dipole-dipole interactions with water molecules. The symmetric structure of the para-methyl group makes the molecular arrangement more compact, further repelling the penetration of water molecules; therefore, the addition of p-methylstyrene can make nylon hydrophobic; 5. In the polymerization reaction, first raise the temperature and pressure, and then slowly reduce the pressure at a constant temperature, which can stabilize the internal structure of the polymer material, avoid incomplete polycondensation and water molecule discharge, and make the properties of the produced material better. Specific Embodiments

[0014] In order to make the technical problems, technical solutions, and beneficial effects to be solved by the present application clearer and more understandable, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0015] Example 1 A preparation method of lightweight hydrophobic long carbon chain nylon specifically includes the following steps: (1). Add 2.3 kg of bio-based dodecanedioic acid, 1.16 kg of bio-based hexamethylenediamine, 1.8 kg of water, 0.7 kg of cellulose nanofibrils, and 0.28 kg of methacrylic acid into a stirring kettle, pass nitrogen to remove the air in the stirring kettle, start stirring, set the temperature to 85 °C and the pressure to 0.2 Mpa, mix for 2 h for reaction, and adjust the pH to 7.3 - 7.8 to obtain a mixed material; (2) While it is still hot, press the mixed materials into the polymerization kettle, charge nitrogen while stirring, add 0.277 kg of p-methylstyrene for mixing, heat up to 205 °C, increase the pressure to 1.5 MPa, and carry out the polymerization reaction for 1 h. Gradually discharge the gas, heat up to 220 °C, slowly reduce the pressure of the polymerization kettle to 0, heat up to 270 °C, and continue the reaction for 1 h. Stop stirring to obtain the polymer material. (3) Apply pressure and extrude and pelletize the polymer material to obtain lightweight hydrophobic long carbon chain PA612-1.

[0016] Example 2 The difference between this example and Example 1 is that the bio-based nanofiller is cellulose nanocrystals, and the rest of the operations are the same, obtaining PA612-2.

[0017] Example 3 The difference between this example and Example 1 is that the bio-based nanofiller is chitin nanofibers, and the rest of the operations are the same, obtaining PA612-3.

[0018] Example 4 The difference between this example and Example 1 is that the mass of cellulose nanofibrils is changed, and the mass ratio of cellulose nanofibrils to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.2:1 to 0.1:1, and the rest of the operations are the same, obtaining PA612-4.

[0019] Example 5 The difference between this example and Example 1 is that the mass of cellulose nanofibrils is changed, and the mass ratio of cellulose nanofibrils to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.2:1 to 0.3:1, and the rest of the operations are the same, obtaining PA612-5.

[0020] Example 6 The difference between this example and Example 1 is that the acrylic derivative is acrylic acid, and the rest of the operations are the same, obtaining PA612-6.

[0021] Example 7 The difference between this example and Example 1 is that the mass of methacrylic acid is changed, and the mass ratio of methacrylic acid to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.06:1; the mass of p-methylstyrene is changed, and the mass ratio of p-methylstyrene to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.06:1, and the rest of the operations are the same, obtaining PA612-7.

[0022] Example 8 The difference between this example and Example 1 is that the mass of methacrylic acid is changed, and the mass ratio of methacrylic acid to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.1:1; the mass of p-methylstyrene is changed, and the mass ratio of p-methylstyrene to the total mass of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.1:1. The rest of the operations are the same, and PA612-8 is obtained.

[0023] Example 9 The difference between this example and Example 1 is that dodecanedioic acid is replaced by sebacic acid to obtain lightweight hydrophobic long carbon chain PA610.

[0024] Comparative Example 1 Add 2.3 kg of dodecanedioic acid, 1.16 kg of hexamethylenediamine, 1.8 kg of water, and 0.7 kg of cellulose nanofibrils into a stirring kettle. Pass nitrogen to remove the air in the stirring kettle, start stirring, set the temperature to 85 °C and the pressure to 0.2 Mpa, mix for 2 h for reaction, adjust the pH to 7.3 - 7.8 to obtain a mixed material; while it is still hot, press the mixed material into a polymerization kettle, stir while filling with nitrogen, raise the temperature to 205 °C, raise the pressure to 1.5 MPa for polymerization reaction for 1 h, gradually discharge the gas, raise the temperature to 220 °C and slowly reduce the pressure of the polymerization kettle to 0, raise the temperature to 270 °C, and continue the reaction for 1 h; stop stirring to obtain a polymer material; apply pressure and extrude and pelletize the polymer material to obtain lightweight hydrophobic long carbon chain PA612-1#.

[0025] Comparative Example 2 Add 2.3 kg of dodecanedioic acid, 1.16 kg of hexamethylenediamine, 1.8 kg of water, 0.7 kg of cellulose nanofibrils, 0.28 kg of methacrylic acid, and 0.277 kg of p-methylstyrene into a polymerization kettle, fill with nitrogen and stir to mix, raise the temperature to 220 °C for polymerization reaction for 5 h, after 5 h, slowly reduce the pressure of the polymerization kettle to 0, raise the temperature to 270 °C, and continue the reaction for 1 h; stop stirring to obtain a polymer material; apply pressure and extrude and pelletize the polymer material to obtain lightweight hydrophobic long carbon chain PA612-2#.

[0026] Experimental Example Perform tensile strength, flexural strength, density, water absorption, and yield tests on the PA prepared in Examples 1 - 9 and Comparative Examples 1 - 2. Table 1 shows the test items and methods, and Table 2 shows the experimental data.

[0027] Table 1 Experimental Test Items and Methods

[0028] Table 2 Experimental Data

[0029] In Comparative Example 1, para-methylstyrene and acrylic acid derivatives were not added, and the prepared nylon had poor hydrophobicity, long polymerization time and low yield. In Comparative Example 2, all components were directly mixed and reacted, the inactivation rate of methacrylic acid was high, the prepared nylon had a high water content, the product chromaticity and internal structure were uneven, and the product performance was poor. The nylon prepared by the formula and method of the present application has uniform product chromaticity and internal structure, good hydrophobicity and mechanical properties. Moreover, the hydrophobic agent is a small molecule compound, and there is no need to use a relative molecular mass regulator, so the cost is low and the preparation process is simple. The nylon has a high bio-based content, less chemical residue, and is green and environmentally friendly. The nylon has both lightweight and hydrophobic dual properties and can be applied to fields such as the automotive field, electronic appliances, ocean engineering or aerospace.

[0030] 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, 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.

[0031] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A preparation method of a lightweight hydrophobic long carbon chain nylon, characterized in that, Specifically, it includes the following steps: (1). Mix aliphatic dibasic acid, hexamethylenediamine, water, bio-based nanofiller, and acrylic derivative in a stirring device, adjust the pH to obtain a mixed material; (2). Press the mixed material into a polymerization kettle, add p-methylstyrene and mix, fill with inert gas, exhaust air, raise the temperature and pressure, and slowly reduce the pressure to carry out a polymerization reaction to obtain a polymer material; (3). Extrude and granulate the polymer material to obtain lightweight hydrophobic long carbon chain nylon.

2. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that, The aliphatic dibasic acid is one of dodecanedioic acid or sebacic acid, the molar ratio of the aliphatic dibasic acid to hexamethylenediamine is 1:1, and the pH of the mixed material is 7.3 - 7.

8.

3. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, wherein, The bio-based nanofiller is one or two of cellulose nanofibrils, cellulose nanocrystals, and chitin nanofibers; the mass ratio of the bio-based nanofiller to the total amount of aliphatic dibasic acid and hexamethylenediamine is 0.1 - 0.3:

1.

4. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that The acrylic derivative is acrylic acid or methacrylic acid.

5. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that, The mass ratio of the acrylic derivative to the total amount of aliphatic dibasic acid and hexamethylenediamine is 0.06 - 0.1:1, and the mass ratio of p-methylstyrene to the total amount of aliphatic dibasic acid and hexamethylenediamine is 0.06 - 0.1:

1.

6. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that, The inert gas is nitrogen, and the mass ratio of water to the total amount of aliphatic dibasic acid and hexamethylenediamine is 0.5:

1.

7. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that, The temperature of the mixing in step (1) is 85 - 95 °C; the mass concentration after the aliphatic dibasic acid and hexamethylenediamine form a salt is 50%.

8. The preparation method of a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that The temperature of the polymerization reaction in step (2) is 200 - 230 °C, and the pressure is 1.5 MPa.

9. A lightweight hydrophobic long carbon chain nylon, characterized in that, Prepared by the preparation method described in claims 1 - 8.

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