Antibacterial polyamide and preparation method thereof

Abstract

The invention relates to antibacterial polyamide and a preparation method thereof. The antibacterial polyamide contains polyamide salt, soluble citrate and soluble non-citrate, and a reaction product is obtained in the presence of a phosphorus catalyst; the preparation method comprises the following steps: uniformly mixing and stirring polyamide salt, a phosphorus catalyst, soluble citrate and soluble non-citrate in the presence of a solvent to obtain a mixed salt solution; wherein the soluble citrate and the soluble non-citric acid are respectively added in the reaction process, and a precipitate is slowly obtained; the solvent comprises water and / or ethanol; evaporating and concentrating the mixed salt solution to remove the solvent, reacting in the presence of protective gas, and fully reacting to obtain the antibacterial polyamide. The antibacterial effect of the antibacterial polyamide is remarkably improved, and the problem that a solid antibacterial agent and polyamide are poor in dispersity is effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyamide resins, and particularly relates to an antibacterial polyamide and a preparation method thereof. Background Art

[0002] Nylon, as a commonly used engineering plastic, has been widely used in fields such as construction, automotive, electronic and electrical, packaging, personal care, and textiles. Therefore, the research and development of nylon products with antibacterial effects will significantly improve people's quality of life and is of great significance to human life and health. At the same time, enhancing the physical properties of nylon while preparing antibacterial nylon materials will enable this type of nylon to be applied in a wider range of fields and bring benefits to more people.

[0003] Inorganic antibacterial agents generally exist in the form of solid powders. They are mainly used as additives and are combined with the preparation processes of corresponding materials to prepare various antibacterial products. Then, the antibacterial, air-cleaning, and disease-preventing functions of inorganic antibacterial agents are exerted through the actual application of antibacterial products. Inorganic antibacterial agents can be classified into two major categories according to the principle of inhibiting and killing bacteria: photocatalytic type and metal ion-carrying type. The former is a semiconductor substance. Under ultraviolet light irradiation, the semiconductor substance generates strongly oxidizing groups such as reactive oxygen species, thereby destroying the cell activity of microorganisms and producing an antibacterial effect. Since the antibacterial agent only has antibacterial function under ultraviolet light irradiation, its scope of application is small, the effect is unstable, and it is difficult to detect and evaluate. The metal ion-carrying type antibacterial agent mainly produces antibacterial effects through ion release, is not restricted by the physical environment, and has the advantages of strong antibacterial effect, good long-term effectiveness, broad-spectrum antibacterial property, and good compatibility with processed products. Currently, metal ion-carrying inorganic antibacterial agents have become the main products in the market for inorganic antibacterial agents. However, there are also some problems in the application process, mainly manifested in two aspects: First, the products change color, that is, the color of antibacterial products prepared by using inorganic antibacterial agents as additives deepens, and even becomes unusable. On the one hand, this is due to the low whiteness of the antibacterial agent itself. On the other hand, and the most important factor is that during the high-temperature and high-pressure process of processing, an excessive amount of inorganic ions in the antibacterial agent escapes and reacts with other components in the product or forms oxides by itself. Since among several metal ions used to prepare inorganic antibacterial agents, silver ions have the strongest antibacterial effect and are easily absorbed and compounded by inorganic carriers, inorganic antibacterial agents are mostly composed of silver ion carriers. Silver ions not only easily cause the products to change color but also increase the cost of inorganic antibacterial agents. Second, the physical properties of inorganic antibacterial agent powders, such as powder particle size, still cannot well meet the application requirements due to problems such as coarse particles and unreasonable distribution.

[0004] With the improvement of science and technology and living standards, people's awareness of safety protection for the living environment has increased, and the demand for functional protective textiles has also become higher and higher. Currently, the fibers used to prepare textiles do not have antibacterial capabilities themselves, and under certain conditions, they may even provide an environment for bacteria to survive and reproduce, threatening human health. The main current method to solve the antibacterial problem of fibers is to use antibacterial nano-ingredients with antibacterial effects to compound and modify the polymer matrix to prepare modified fibers with antibacterial effects. Currently, antibacterial fibers are widely used and in high demand, but the existing technologies cannot effectively solve problems such as a large amount of functional components added, difficult dispersion, unstable high-temperature processing, and low production rate in continuous production, resulting in the inability to effectively form large-scale production of antibacterial fibers and difficulty in meeting the wide market demand.

[0005] Currently, the main methods to endow fibers with antibacterial functions are through surface modification technology and blending modification technology. In Patent CN113502660A, alkyl diguanide salts and polyamides are polymerized to obtain modified polyamide fibers, and then a finishing agent is sprayed onto the fibers; this technology has complex operations, uneven distribution of antibacterial components, a large addition amount, and requires post-finishing to ensure antibacterial effects. In Patent CN101942759A, fibers are added to a solution containing silver nitrate to adsorb silver nitrate in the solution, and then the adsorbed fibers are reduced to obtain antibacterial fibers or fabrics with silver attached to the surface. This method cannot form a uniform and stable antibacterial coating, and the antibacterial time is limited, unable to achieve long-lasting antibacterial effects. Summary of the Invention

[0006] Technical Problem: To overcome the above technical defects, the purpose of the present invention is to disclose an antibacterial polyamide and its preparation method, with a significant improvement in antibacterial effect and effectively avoiding the problem of poor dispersibility of solid antibacterial agents and polyamides.

[0007] Technical Solution: An antibacterial polyamide of the present invention contains a reaction product obtained from polyamide salt, soluble citrate, soluble non-citrate in the presence of a phosphorus catalyst; the mass percentages of the raw material components are as follows:

[0008]

[0009] The polyamide salt includes one or more of polyamide 66 salt, polyamide 510 salt, polyamide 610 salt, and polyamide 612 salt.

[0010] The phosphorus catalyst contains groups reactive to polyamides, and the groups include one or a combination of two of carboxyl group and amino group.

[0011] The phosphorus catalyst includes one or more of carboxyphenylphosphoric acid, aminophenylphosphoric acid, and their derivatives.

[0012] The soluble citrate includes one or more of lithium citrate, sodium citrate, potassium citrate, and ammonium citrate.

[0013] The soluble non-citrate includes one or more of silver acetate, calcium acetate, zinc acetate, silver nitrate, calcium nitrate, and zinc nitrate.

[0014] The preparation method of the antibacterial polyamide of the present invention includes the following steps:

[0015] Step 1, mixing and stirring evenly polyamide salt, phosphorus catalyst, soluble citrate, and soluble non-citrate in the presence of a solvent to obtain a mixed salt solution; wherein, the soluble citrate and soluble non-citrate are added separately during the reaction, and a precipitate is slowly obtained; the solvent includes water and / or ethanol;

[0016] Step 2, evaporating and concentrating the above mixed salt solution to remove the solvent, and reacting in the presence of a protective gas. After sufficient reaction, an antibacterial polyamide is obtained; the protective gas includes one or more of nitrogen, carbon dioxide, argon, and helium; the reaction temperature is 150-280°C, and the pressure is 0-2.0 MPa.

[0017] The precipitate obtained by the reaction of the soluble citrate and soluble non-citrate is insoluble in water.

[0018] When the valence state of the cation in the soluble non-citrate is +1, the molar ratio of the cation in the soluble non-citrate to the citrate root in the citrate is 3:1 to 4:1;

[0019] When the valence state of the cation in the soluble non-citrate is +2, the molar ratio of the cation in the soluble non-citrate to the citrate root in the citrate is 1.5:1 to 1.8:1.

[0020] The mass content of the mixed salt solution is 50-65%.

[0021] Beneficial effects: The present invention introduces a phosphorus catalyst into the polyamide, which plays a dual role of catalysis and reaction; during the polyamide salt polymerization reaction, soluble citrate and soluble non-citrate are added separately, and the two can slowly generate a poorly soluble antibacterial agent. By stirring, the antibacterial agent can be fully mixed with the polyamide salt, significantly improving the antibacterial effect and effectively avoiding the problem of poor dispersion of the solid antibacterial agent and polyamide. Specific embodiments

[0022] The antibacterial polyamide contains the reaction product of polyamide salt, soluble citrate, and soluble non-citrate in the presence of a phosphorus catalyst;

[0023] The antibacterial polyamide comprises the following raw material components in mass percentage:

[0024]

[0025] Among them, the reaction product obtained by reacting the soluble citrate with the soluble non-citrate is insoluble in water;

[0026] In some examples of the present invention:

[0027] When the valence state of the cation in the soluble non-citrate is +1, in some examples of the present invention, the molar ratio of the cation in the soluble non-citrate to the citrate radical in the citrate is 3:1 to 4:1, preferably 3:1 to 3.5:1;

[0028] When the valence state of the cation in the soluble non-citrate is +2, in some examples of the present invention, the molar ratio of the cation in the soluble non-citrate to the citrate radical in the citrate is 1.5:1 to 1.8:1, preferably 1.5:1 to 1.6:1;

[0029] The polyamide salt includes one or more of polyamide 66 salt, polyamide 510 salt, polyamide 610 salt, and polyamide 612 salt;

[0030] In some examples of the present invention, the polyamide salt includes one or more of polyamide 66 salt, polyamide 610 salt, and polyamide 612 salt;

[0031] The phosphorus catalyst contains groups that are reactive to polyamides, and the groups include one or a combination of two of carboxyl groups and amino groups;

[0032] Furthermore, the phosphorus catalyst includes one or more of carboxyphenylphosphoric acid, aminophenylphosphoric acid, and its derivatives;

[0033] In some examples of the present invention, the phosphorus catalyst includes one or more of 2-carboxyphenylphosphoric acid, 3-carboxyphenylphosphoric acid, 4-carboxyphenylphosphoric acid, bis(4-carboxyphenyl)phosphoric acid, 2-aminophenylphosphoric acid, 3-aminophenylphosphoric acid, and 4-aminophenylphosphoric acid;

[0034] The citrate includes one or more of lithium citrate, sodium citrate, potassium citrate, and ammonium citrate;

[0035] The soluble non-citrate includes one or more of silver acetate, calcium acetate, zinc acetate, silver nitrate, calcium nitrate, and zinc nitrate;

[0036] In some examples of the present invention, the non-citrate includes one or more of silver acetate, calcium acetate, and zinc acetate;

[0037] The preparation method of the antibacterial polyamide of the present invention includes the following steps:

[0038] Mix the polyamide salt, phosphorus catalyst, citrate, and soluble non-citrate evenly under the presence of a solvent to obtain a mixed salt solution;

[0039] Evaporate and concentrate the above mixed salt solution to remove the solvent and fully react to obtain antibacterial polyamide.

[0040] Among them, the solvent includes water and / or ethanol;

[0041] The mass content of the mixed salt solution is 50-65%;

[0042] The reaction temperature is 150-280 °C and the pressure is 0-2.0 MPa;

[0043] Preferably, the above preparation steps are carried out in the presence of a protective gas, including one or more of nitrogen, carbon dioxide, and argon;

[0044] In the present invention, the polyamide salt can be commercially available or prepared by reacting a diamine and a dicarboxylic acid;

[0045] As an example, the preparation method of the antibacterial polyamide of the present invention specifically includes the following steps:

[0046] Mix the polyamide salt solution, phosphorus catalyst solution, and citrate solution evenly at a temperature of 60-80 °C in the dark and in the presence of a protective gas, and slowly add the soluble non-citrate solution during this period and stir well to obtain a mixed salt solution;

[0047] Among them, the solvent is deionized water, the mass concentration of the polyamide salt solution is 50-60%, and the pH value of the polyamide salt solution is 7.0-8.5; the mass concentration of the phosphorus catalyst solution is 5-10%, and the mass concentration of the citrate solution is 5-10%; the mass concentration of the mixed salt solution is 50-65%, and the pH value of the mixed salt solution is 7.0-8.5;

[0048] Heat the mixed salt solution to 150-160 °C and pressurize it to 0.2-0.4 MPa in a protective gas atmosphere, and evaporate and concentrate it to a solution with a mass concentration of 70-80%; raise the temperature and pressure to 210-220 °C and 1.5-1.9 MPa respectively, and the time for the pressure and temperature increase stage is 30-60 minutes; maintain this pressure for 60-120 minutes, and during this period the temperature rises to 240-250 °C; reduce the pressure to 0 MPa, and the temperature gradually rises to 250-260 °C during the pressure reduction, and the time for the pressure reduction stage is 30-60 minutes; maintain the pressure and temperature unchanged and continue to react for 20-60 minutes to obtain antibacterial polyamide.

[0049] Preferably, additives well-known in the art are added in the above steps, including antioxidants, photothermal stabilizers, end group regulators, flame retardants, and high temperature resistant additives;

[0050] The antioxidant is selected from hindered phenols, thioesters, phosphites, and aromatic amine antioxidants;

[0051] The photothermal stabilizer is selected from hindered amines, benzotriazoles, or benzophenone photothermal stabilizers;

[0052] The end group regulator is selected from one or more of n-butylamine, n-pentylamine, n-hexylamine, benzylamine, phenethylamine, acetic acid, propionic acid, butyric acid, benzoic acid, and phenylacetic acid;

[0053] The heat resistant agent is selected from organic copper compounds, inorganic copper salts, and aromatic amine high temperature resistant additives;

[0054] The flame retardant is selected from organophosphorus-based, organoaluminum-based, and melamine-based flame retardants.

[0055] The principles and features of the present invention will be described below in conjunction with implementation examples. The examples are given to facilitate better understanding of the present invention by those skilled in the art. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0056] Example 1

[0057] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0058]

[0059]

[0060] Among them, the molar ratio of silver ions in silver acetate to citrate ions in citrate is about 3.25:1.

[0061] Example 2

[0062] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0063]

[0064] Among them, the molar ratio of calcium ions in calcium acetate to citrate ions in citrate is about 1.59:1.

[0065] Example 3

[0066] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0067]

[0068] Among them, the molar ratio of silver ions in silver nitrate to citrate ions in citrate is about 3.07:1.

[0069] Example 4

[0070] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0071]

[0072] Among them, the molar ratio of zinc ions in zinc acetate to citrate ions in citrate is about 1.77:1.

[0073] Example 5

[0074] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0075]

[0076]

[0077] Among them, the molar ratio of silver ions in silver acetate to citrate ions in citrate is about 3.25:1.

[0078] Example 6

[0079] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0080]

[0081] Among them, the molar ratio of silver ions in silver acetate to citrate ions in citrate is about 6.44:1.

[0082] Example 7

[0083] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0084]

[0085] Among them, the molar ratio of calcium ions in calcium acetate to citrate ions in citrate is about 0.66:1.

[0086] Example 8

[0087] The antibacterial polyamide described above comprises the following raw material components in mass percentage:

[0088]

[0089] Among them, the molar ratio of silver ions in silver nitrate to citrate ions in citrate is about 5.57:1.

[0090] Comparative Example 1

[0091] The difference from Example 1 is that silver citrate finished products of equal mass are directly used to replace sodium citrate and silver acetate.

[0092] Comparative Example 2

[0093] The difference from Example 1 is that sodium chloride of equal mass is directly used to replace sodium citrate.

[0094] Comparative Example 3

[0095] The difference from Example 1 is that no phosphorus catalyst is added.

[0096] Comparative Example 4

[0097] The difference from Example 1 is that no sodium citrate and silver acetate are added.

[0098] Polyamides were respectively prepared according to the raw material components of the above-mentioned examples and comparative examples, and performance tests were carried out on the polyamide samples. The test methods and standards for each performance parameter are as follows:

[0099] 1. Melting point: ASTM D3418.

[0100] 2. Viscosity number: ISO 307.

[0101] 3. Mechanical properties: The tensile strength was tested with reference to the standard ISO527, and the notched impact strength of the simply supported beam was tested with reference to the standard ISO 179.

[0102] 4. Antibacterial property: With reference to QB / T 2591-2003A "Test Methods for Antibacterial Properties and Antibacterial Effects of Antibacterial Plastics", Escherichia coli ATCC 25922 was used to detect the antibacterial rate after 24 h; the antibacterial rate was tested after the sample was placed under the conditions of 85% relative humidity and 85 °C for 500 h.

[0103] The performance test results are as follows:

[0104]

[0105] In addition, the yellowness indices of Examples 1 to 5 are all below 2, the yellowness indices of Examples 6 to 8 are below 4, and the yellowness indices of Comparative Examples 1 to 4 are above 4.

Claims

1. An antibacterial polyamide, characterized in that The antibacterial polyamide contains a reaction product obtained from polyamide salt, soluble citrate, soluble non-citrate in the presence of a phosphorus catalyst; the mass percentages of the raw material components are as follows:

2. The antibacterial polyamide according to claim 1, wherein The polyamide salt described above includes one or more of polyamide 66 salt, polyamide 510 salt, polyamide 610 salt, and polyamide 612 salt.

3. The antibacterial polyamide according to claim 1, wherein The phosphorus catalyst contains groups that are reactive to polyamide, and the groups include one or a combination of two of carboxyl group and amino group.

4. The antibacterial polyamide according to claim 1, characterized in that, The phosphorus catalyst includes one or more of carboxyphenylphosphoric acid, aminophenylphosphoric acid, and their derivatives.

5. The antibacterial polyamide according to claim 1, wherein The soluble citrate includes one or more of lithium citrate, sodium citrate, potassium citrate, and ammonium citrate.

6. The antibacterial polyamide according to claim 1, wherein The soluble non-citrate includes one or more of silver acetate, calcium acetate, zinc acetate, silver nitrate, calcium nitrate, and zinc nitrate.

7. A method for preparing the antibacterial polyamide according to claim 1, characterized in that, The preparation method includes the following steps: Step 1, mix and stir evenly polyamide salt, phosphorus catalyst, soluble citrate, and soluble non-citrate in the presence of a solvent to obtain a mixed salt solution; wherein, the soluble citrate and soluble non-citrate are added separately during the reaction, and a precipitate is slowly obtained; the solvent includes water and / or ethanol; Step 2, evaporate and concentrate the above mixed salt solution to remove the solvent, carry out the reaction in the presence of a protective gas, and obtain the antibacterial polyamide after sufficient reaction; the protective gas includes one or more of nitrogen, carbon dioxide, argon, and helium; the reaction temperature is 150 - 280 °C, and the pressure is 0 - 2.0 MPa.

8. The method for preparing an antibacterial polyamide according to claim 7, characterized in that, The precipitate obtained from the reaction of the soluble citrate and soluble non-citrate is insoluble in water.

9. The method for preparing an antibacterial polyamide according to claim 7, characterized in that, When the cation valence state in the soluble non-citrate is +1, the molar ratio of the cation in the soluble non-citrate to the citrate root in the citrate is 3:1 - 4:1; When the cation valence state in the soluble non-citrate is +2, the molar ratio of the cation in the soluble non-citrate to the citrate root in the citrate is 1.5:1 - 1.8:

1.

10. The preparation method of the antibacterial polyamide according to claim 7, characterized in that, The mass content of the mixed salt solution is 50 - 65%.

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