A lightweight hydrophobic long carbon chain nylon and its preparation method

Abstract

The present application discloses a lightweight, hydrophobic, long-carbon-chain nylon and a preparation method thereof, which belongs to the technical field of polyamide materials. The method comprises the following steps: mixing an aliphatic dibasic acid, hexamethylenediamine, water, a bio-based nanofiller, and an acrylic acid derivative in a stirring device, and adjusting the pH to obtain a mixed material; pressing the mixed material into a polymerization kettle, adding p-methylstyrene and mixing, filling with inert gas, exhausting air, increasing the temperature and pressure, and slowly reducing the pressure to carry out a polymerization reaction to obtain a polymer material; and extruding the polymer material into pellets to obtain a lightweight, hydrophobic, long-carbon-chain nylon. The nylon material obtained by this method has good mechanical properties, a simple preparation process, low chemical residues, and is green and environmentally friendly. The nylon has both lightweight and hydrophobic properties and can be used in the automotive field, electronic appliances, marine engineering, aerospace, and other fields.

Description

Technical Field

[0001] The present application belongs to the technical field of polyamide materials, and in particular relates to a lightweight hydrophobic long carbon chain nylon and a preparation method thereof. Background Art

[0002] Materials used in the automotive, electronics, marine engineering or aerospace fields all need to meet lightweight requirements to reduce the weight of the product and achieve better performance. Moreover, in the above-mentioned fields, they are mostly used in precision electronic equipment. Traditional long-carbon-chain nylon contains a large number of polar amide bonds and is easy to absorb water, resulting in decreased dimensional stability and mechanical properties, limiting its application in high-demand working environments. Traditional hydrophobic modification technologies mostly use copolymerization modification (introduction of fluorine-containing monomers or siloxanes), surface treatment (plasma coating, chemical vapor deposition) and other technologies, which have complex processes, high technical costs, and poor hydrophobic effects. Lightweight hydrophobic long-carbon-chain nylon is a high-performance polyamide material that combines low density, high hydrophobicity and a long carbon chain structure. Most current nylons are single-function nylons that do not have the above functions at the same time, resulting in the development of nylon in the automotive, electronics, marine engineering or aerospace fields being restricted.

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

[0004] The purpose of the present application is to provide a lightweight hydrophobic long carbon chain nylon and its preparation method, so as to solve the technical problems that the existing hydrophobic nylon mostly uses a polymer mixture as a hydrophobic agent, the preparation process is complicated, and the obtained nylon has poor performance and single function.

[0005] To achieve the above objectives, the technical solution adopted in this application is to provide a lightweight hydrophobic long carbon chain nylon and a preparation method thereof, which specifically includes the following steps:

[0006] (1) mixing an aliphatic dibasic acid, hexamethylenediamine, water, a bio-based nanofiller, and an acrylic acid derivative in a stirring device, and adjusting the pH to obtain a mixed material;

[0007] (2) Pressing the mixed material into a polymerization kettle, adding p-methylstyrene and mixing, filling with inert gas, exhausting air, increasing the temperature and pressure, and slowly reducing the pressure to carry out polymerization reaction to obtain a polymer material;

[0008] (3) The polymer material is extruded, formed and pelletized to obtain lightweight hydrophobic long carbon chain nylon.

[0009] In one embodiment,

[0010] 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 mixture is 7.3-7.8.

[0011] In one embodiment,

[0012] 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 dicarboxylic 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 aliphatic dicarboxylic acid and hexamethylenediamine is 0.2:1.

[0013] In one embodiment,

[0014] The acrylic acid derivative is acrylic acid or methacrylic acid. Preferably, the acrylic acid derivative is methacrylic acid.

[0015] In one embodiment,

[0016] The mass ratio of the acrylic acid 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 acid 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.

[0017] In one embodiment,

[0018] 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.

[0019] In one embodiment,

[0020] The mixing temperature in step (1) is 85-95°C; the mass concentration of the salt of the aliphatic dibasic acid and hexamethylenediamine is 50%;

[0021] In one embodiment,

[0022] The polymerization reaction temperature in step (ii) is 200-230°C and the pressure is 1.5 MPa.

[0023] The present application also provides a lightweight hydrophobic long carbon chain nylon, which is prepared using the preparation method of any of the above embodiments.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] 1. By adjusting the ratio of aliphatic dibasic acid and hexamethylenediamine, the pH is precisely adjusted to 7.3-7.8 to fully polymerize the raw materials and reduce the escape of excess monomers. The aliphatic dibasic acid and hexamethylenediamine are bio-based raw materials, which increases the bio-based content of nylon and is more environmentally friendly.

[0026] 2. Bio-based nanofillers are nano-scale reinforcing materials made from natural biomass. Cellulose nanofibrils and cellulose nanocrystals are derived from wood, straw, or bacterial cellulose. They have high specific surface area and strength, approaching those of carbon fibers. Their nanostructure provides more interfacial binding sites, significantly enhancing the mechanical properties of nylon materials. The addition of bio-based nanofillers makes the components more evenly dispersed, improves the biocompatibility of each component, and reduces agglomeration, making them particularly suitable for bio-based nylon. Adding bio-based nanofillers to nylon reduces its density due to its nanostructure, making the nylon lightweight.

[0027] 3. The carboxyl group of acrylic acid derivatives can improve the dispersibility of components in the aqueous phase, facilitate the polymerization reaction, and enable nylon materials to maintain mechanical strength while reducing density;

[0028] 4. The benzene ring and the para-methyl group in the structure of p-methylstyrene form a completely non-polar structure, which cannot form hydrogen bonds or dipole interactions with water molecules. The symmetrical structure of the para-methyl group makes the molecules more tightly arranged, further repelling the penetration of water molecules; therefore, the addition of p-methylstyrene can make nylon hydrophobic;

[0029] 5. During the polymerization reaction, first increase the temperature and pressure and then slowly reduce the pressure at a constant temperature. This can stabilize the internal structure of the polymer material, avoid condensation and incomplete discharge of water molecules, and make the produced material have better performance. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clear and understandable, this application is 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.

[0031] Example 1

[0032] The preparation method of lightweight hydrophobic long carbon chain nylon specifically comprises the following steps:

[0033] (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 stirred tank, remove air from the stirred tank by nitrogen, start stirring, set the temperature to 85°C and the pressure to 0.2 MPa, mix for 2 h to react, and adjust the pH to 7.3-7.8 to obtain a mixed material;

[0034] (2) While hot, press the mixture into a polymerization kettle, fill it with nitrogen while stirring, add 0.277 kg of p-methylstyrene, mix, raise the temperature to 205°C, raise the pressure to 1.5 MPa, and carry out polymerization reaction for 1 hour. Gradually discharge the gas, raise the temperature to 220°C, slowly reduce the pressure of the polymerization kettle to 0, raise the temperature to 270°C, and continue the reaction for 1 hour; stop stirring to obtain a polymer material;

[0035] (3) Pressurizing, extruding, shaping and pelletizing the polymer material to obtain lightweight hydrophobic long carbon chain PA612-1.

[0036] Example 2

[0037] This embodiment differs from embodiment 1 in that the bio-based nanofiller is cellulose nanocrystals. The remaining operations are the same to obtain PA612-2.

[0038] Example 3

[0039] This embodiment differs from embodiment 1 in that the bio-based nanofiller is chitin nanofiber, and the remaining operations are the same to obtain PA612-3.

[0040] Example 4

[0041] This embodiment differs from embodiment 1 in that the mass of the cellulose nanofibrils is changed, and the mass ratio of the cellulose nanofibrils to the total amount of dodecanedioic acid and hexamethylenediamine is changed from 0.2:1 to 0.1:1. The remaining operations are the same to obtain PA612-4.

[0042] Example 5

[0043] This embodiment differs from embodiment 1 in that the mass of the cellulose nanofibrils is changed, and the mass ratio of the cellulose nanofibrils to the total amount of dodecanedioic acid and hexamethylenediamine is changed from 0.2:1 to 0.3:1. The remaining operations are the same to obtain PA612-5.

[0044] Example 6

[0045] This embodiment differs from embodiment 1 in that the acrylic acid derivative is acrylic acid, and the remaining operations are the same to obtain PA612-6.

[0046] Example 7

[0047] This example differs from Example 1 in that the mass of methacrylic acid is changed, and the mass ratio of methacrylic acid to the total amount 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 amount of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.06:1. The remaining operations are the same to obtain PA612-7.

[0048] Example 8

[0049] This example differs from Example 1 in that the mass of methacrylic acid is changed, and the mass ratio of methacrylic acid to the total amount 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 amount of dodecanedioic acid and hexamethylenediamine is changed from 0.08:1 to 0.1:1. The remaining operations are the same to obtain PA612-8.

[0050] Example 9

[0051] This embodiment differs from embodiment 1 in that dodecanedioic acid is replaced with sebacic acid to obtain a lightweight, hydrophobic, long-carbon-chain PA610.

[0052] Comparative Example 1

[0053] 2.3 kg of dodecanedioic acid, 1.16 kg of hexamethylenediamine, 1.8 kg of water, and 0.7 kg of cellulose nanofibrils were added to a stirring kettle, nitrogen was passed through the stirring kettle to remove air, stirring was started, the temperature was set to 85°C and the pressure was set to 0.2 MPa, mixing was carried out for 2 hours to react, and the pH was adjusted to 7.3-7.8 to obtain a mixed material; while the hot mixture was pressed into a polymerization kettle, nitrogen was introduced while stirring, the temperature was raised to 205°C, the pressure was raised to 1.5 MPa, polymerization reaction was carried out for 1 hour, the gas was gradually discharged, the temperature was raised to 220°C, the pressure of the polymerization kettle was slowly reduced to 0, the temperature was raised to 270°C, and the reaction was continued for 1 hour; stirring was stopped to obtain a polymer material; the polymer material was pressurized, extruded, formed and pelletized to obtain a lightweight hydrophobic long carbon chain PA612-1#.

[0054] Comparative Example 2

[0055] 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 were added to a polymerization kettle, filled with nitrogen and stirred, and the temperature was raised to 220°C for polymerization for 5 h. After 5 h, the pressure of the polymerization kettle was slowly reduced to 0, the temperature was raised to 270°C, and the reaction was continued for 1 h. Stirring was stopped to obtain a polymer material. The polymer material was pressurized, extruded, formed, and pelletized to obtain lightweight hydrophobic long-chain PA612-2#.

[0056] Experimental example

[0057] The PA prepared in Examples 1-9 and Comparative Examples 1-2 were tested for tensile strength, flexural strength, density, water absorption, and yield. Table 1 shows the test items and methods, and Table 2 shows the experimental data.

[0058] Table 1 Experimental test items and methods

[0059]

[0060] Table 2 Experimental data

[0061]

[0062] In Comparative Example 1, no p-methylstyrene and acrylic acid derivatives were added, resulting in poor hydrophobicity, a long polymerization time, and a low yield of the obtained nylon. In Comparative Example 2, all components were mixed and reacted directly, resulting in a high deactivation rate of methacrylic acid, a high water content of the obtained nylon, uneven product color and internal structure, and poor product performance. The nylon prepared using the formula and method of the present application has uniform product color and internal structure, good hydrophobicity and mechanical properties, and the hydrophobic agent is a small molecule compound, eliminating the need for a relative molecular mass regulator, resulting in low cost and a simple preparation process. The nylon has a high bio-based content, low chemical residues, and is green and environmentally friendly. The nylon has both lightweight and hydrophobic properties and can be used in the automotive, electronics, marine engineering, aerospace, and other fields.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0064] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing lightweight hydrophobic long carbon chain nylon, characterized in that: The specific steps include: (1) mixing an aliphatic dibasic acid, hexamethylenediamine, water, a bio-based nanofiller, and an acrylic acid derivative in a stirring device, and adjusting the pH to obtain a mixed material; (2) Pressing the mixed material into a polymerization kettle, adding p-methylstyrene and mixing, filling with inert gas, exhausting air, increasing the temperature and pressure, and slowly reducing the pressure to carry out polymerization reaction to obtain a polymer material; (3) Extruding the polymer material into pellets to obtain lightweight hydrophobic long carbon chain nylon; The acrylic acid derivative is acrylic acid or methacrylic acid.

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

8.

3. The method for preparing a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that: 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 method for preparing a lightweight hydrophobic long carbon chain nylon according to claim 1, characterized in that: The mass ratio of the acrylic acid 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.

5. The method for preparing 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 the aliphatic dibasic acid and hexamethylenediamine is 0.5:

1.

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

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

8. A lightweight hydrophobic long carbon chain nylon, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 7.

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