High temperature resistant copolymerized flame retardant for nylon resin and preparation method thereof

Abstract

This invention belongs to the field of polymer organic chemistry technology and discloses a high-temperature resistant copolymer flame retardant for nylon resin and its preparation method. Under nitrogen protection, the flame retardant is prepared in a two-step process using triphenyl phosphite, cyanuric chloride, and terephthalic acid or 1,6-naphthalenedicarboxylic acid as raw materials. The resulting flame retardant is a halogen-free, environmentally friendly, and high-temperature resistant intrinsic flame retardant. This flame retardant requires a small dosage, and the resulting nylon resin maintains high flame retardant performance without affecting its mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer organic chemistry technology. This invention relates to a high-temperature resistant copolymer flame retardant for nylon resin and its preparation method. Background Technology

[0002] With the rapid development of high-end fields such as electronics, rail transportation, electric vehicles, and aerospace, nylon, as the most widely used engineering plastic, faces increasingly harsh operating environments, such as high temperature, high humidity, high voltage, and high load. This places higher demands on the heat resistance and flame retardancy of nylon materials, making the development and research of high-temperature flame retardants crucial.

[0003] Currently, nylon flame retardants are classified into halogen-based, inorganic metal-based, phosphorus-based, nitrogen-based, and biomass-based flame retardants. Halogen-based flame retardants produce a large amount of harmful gases during combustion. With increasing environmental awareness, flame retardants are gradually shifting towards halogen-free and environmentally friendly alternatives. Inorganic metal-based flame retardants suffer from extremely low flame retardant efficiency, requiring large quantities to achieve the desired effect. However, excessive addition of inorganic metal-based flame retardants inevitably leads to deterioration of the polymer's mechanical properties. As demands for high-quality materials increase, the trend towards halogen-free, environmentally friendly flame retardants that do not impair the mechanical properties of nylon resin is growing. Currently, halogen-free flame retardants used in nylon applications are not heat-resistant, require large addition amounts to achieve the desired flame retardant effect, and their addition also affects the mechanical properties of nylon resin.

[0004] Chinese invention patent CN114736430B discloses a P / N multi-element reactive nylon 66 flame retardant and its preparation method. The flame retardant is prepared by compounding triphenyl phosphite (or methyl phosphite), cyanuric chloride, and β-alanine. Although the nylon resin prepared by this flame retardant solves the problems of harmful gas generation and poor flame retardant performance of the above-mentioned halogenated flame retardants, the patent does not evaluate whether the flame retardant affects the mechanical properties and temperature resistance of the material. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a high-temperature resistant copolymer flame retardant for nylon resin and its preparation method. The prepared flame retardant is a halogen-free, environmentally friendly, and high-temperature resistant intrinsic flame retardant. The amount of the flame retardant added is small, and the nylon resin prepared does not affect its mechanical properties while ensuring high flame retardant performance.

[0006] The above-mentioned objective of this invention is achieved through the following technical solution:

[0007] The first objective of this invention is to claim protection for a high-temperature copolymer flame retardant for nylon resin, the flame retardant having a structure as shown in Formula I.

[0008]

[0009] The R group is either phenyl or naphthyl.

[0010] Furthermore, the R group is preferably benzene or naphthalene.

[0011] The second objective of this invention is to claim protection for the preparation method of the above-mentioned high-temperature copolymer flame retardant for nylon resin, wherein the flame retardant is prepared in a two-step process using triphenyl phosphite, cyanuric chloride and terephthalic acid or 1,6-naphthalenedicarboxylic acid as raw materials under nitrogen protection.

[0012] Furthermore, the preparation method of the high-temperature resistant copolymer flame retardant for nylon resin includes the following specific steps:

[0013] The first step is the preparation of flame retardant intermediates;

[0014] Under nitrogen protection, triphenyl phosphite, cyanuric chloride, and acetone solvent are added to a reactor. The reaction temperature is 2-8℃ and the reaction time is 1-2h. After the reaction is completed, the solvent and by-products are evaporated and rotary evaporated to generate a flame retardant intermediate. The flame retardant intermediate has the structure shown in Formula II.

[0015]

[0016] The second step is the preparation of NP-synergistic flame retardants;

[0017] The flame retardant intermediate prepared in the first step was added dropwise to a solution of terephthalic acid or 1,6-naphthalenedicarboxylic acid at a reaction temperature of 80℃-100℃ for 4-6 hours, resulting in a pale yellow precipitate. Finally, the solution was filtered to obtain the crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the NP synergistic flame retardant.

[0018] Furthermore, in the first step, the molar ratio of triphenyl phosphite to cyanuric chloride is 1:1 to 1.4.

[0019] Furthermore, in the second step, the molar ratio of the flame retardant intermediate obtained in the first step to terephthalic acid or 1,6-naphthalenedicarboxylic acid is 1 to 2:2.2.

[0020] The preferred molar ratio of the flame retardant intermediate to terephthalic acid or 1,6-naphthalenedicarboxylic acid is ~2:2.2.

[0021] The preparation method of a high-temperature copolymer flame retardant for nylon resin, the reaction formula of which is shown below.

[0022] Step 1: Preparation of flame retardant intermediates

[0023]

[0024] The second step is the preparation of NP-synergistic flame retardants.

[0025]

[0026] A third objective of this invention is to protect the use of the flame retardant prepared by the above-described method in the preparation of nylon resin.

[0027] The beneficial effects of this invention compared to the prior art are:

[0028] The halogen-free flame retardant prepared by this invention has high-temperature resistance and minimal impact on the mechanical properties of nylon products. When added at approximately 6% (mass percentage), the flame retardant effect on nylon resin is excellent, achieving a UL94 V-0 rating. The flame retardant's unique benzene ring (or naphthalene ring) structure enables it to withstand high temperatures, and the preparation method is relatively simple, with easily achievable process conditions. Attached Figure Description

[0029] Figure 1 This is a graph showing the TGA test results of the flame retardant prepared in Example 2. Detailed Implementation

[0030] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0031] Example 1

[0032] A method for preparing a high-temperature resistant copolymer flame retardant for nylon resin, specifically comprising:

[0033] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor. The reaction temperature was 2°C, and the reaction was continued at this temperature for 1 hour after the addition was complete, generating a flame retardant intermediate. 2.2 mol of terephthalic acid was weighed, and the temperature was raised to 50°C. The synthesized intermediate was added dropwise to the terephthalic acid solution. After the addition was complete, the temperature was raised to 80°C, and the reaction was continued for 4 hours. Finally, the solution was filtered to obtain a crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the flame retardant.

[0034] Example 2

[0035] A method for preparing a high-temperature resistant copolymer flame retardant for nylon resin, specifically comprising:

[0036] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor at 4°C. After the addition was complete, the reaction was carried out at this temperature for 1.5 h to generate a flame retardant intermediate. 2.2 mol of terephthalic acid was weighed and the synthesized intermediate was added dropwise to the terephthalic acid solution at 50°C. After the addition was complete, the temperature was raised to 90°C and the reaction was carried out for 5 h. Finally, the solution was filtered to obtain the crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the flame retardant.

[0037] TGA testing was performed on Example 2, and the test results are shown below. Figure 1 .

[0038] As shown in TGA curve 1, the halogen-free flame retardant loses 5% at 280℃, which is recorded as the initial decomposition temperature. The decomposition reaches its maximum at around 360℃, and then tends to stabilize after about 480℃, with a final char yield of 16%. Therefore, the halogen-free flame retardant prepared by this invention is not easily decomposed at high polymerization temperatures, and the flame retardant is heat-resistant, which meets the polymerization requirements of nylon materials.

[0039] Example 3

[0040] A method for preparing a high-temperature resistant copolymer flame retardant for nylon resin, specifically comprising:

[0041] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor at 8°C. After the addition was complete, the reaction was carried out at this temperature for 2 hours to generate a flame retardant intermediate. 22 mol of terephthalic acid was weighed and the synthesized intermediate was added dropwise to the terephthalic acid solution at 50°C. After the addition was complete, the temperature was raised to 100°C and the reaction was carried out for 6 hours. Finally, the solution was filtered to obtain a crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the flame retardant.

[0042] Example 4

[0043] A method for preparing a high-temperature resistant copolymer flame retardant for nylon resin, specifically comprising:

[0044] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor at 4°C. After the addition was complete, the reaction was allowed to proceed at this temperature for 1.5 h to generate a flame retardant intermediate. 2.2 mol of 1,6-naphthalenedicarboxylic acid was weighed and added dropwise to a terephthalic acid solution at 50°C. After the addition was complete, the temperature was raised to 90°C and the reaction was allowed to proceed for 5 h. Finally, the solution was filtered to obtain a crude product, which was then washed with acetone and anhydrous ethanol and dried to obtain the flame retardant.

[0045] Comparative Example 1

[0046] The preparation method of the flame retardant is as follows:

[0047] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor. The reaction temperature was 10℃. After the addition was complete, the reaction was carried out at this temperature for 2 hours to generate a flame retardant intermediate. 2.2 mol of terephthalic acid was weighed and the synthesized intermediate was added dropwise to the terephthalic acid solution at 50℃. After the addition was complete, the temperature was raised to 120℃ and the reaction was carried out for 6 hours. Finally, the solution was filtered to obtain a crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the flame retardant.

[0048] Comparative Example 2

[0049] The preparation method of the flame retardant is as follows:

[0050] Under N2 gas protection, 1 mol of cyanuric chloride was dissolved in 3 mol of acetone solution and added to a reactor. 1.2 mol of triphenyl phosphite was weighed into a constant-pressure dropping funnel, and then the triphenyl phosphite solution was added dropwise to the reactor. The reaction temperature was 8°C. After the addition was complete, the reaction was carried out at this temperature for 4 hours to generate a flame retardant intermediate. 2.2 mol of terephthalic acid was weighed, and the synthesized intermediate was added dropwise to the terephthalic acid solution at 60°C. After the addition was complete, the temperature was raised to 100°C and the reaction was carried out for 8 hours. Finally, the solution was filtered to obtain the crude product, which was then washed and dried with acetone and anhydrous ethanol to obtain the flame retardant.

[0051] Comparative Example 3

[0052] The preparation method of the flame retardant is as follows: Under nitrogen protection, 2 mol of cyanuric chloride is added to a three-necked flask, followed by 3 mol of acetone and 2 mol of triethylamine. The mixture is stirred in a water bath at 5°C for 0.5 h. Then, a mixed solution of 2 mol of triphenyl phosphite and 0.5 ml of acetone is added through a constant-pressure funnel. After the addition is complete, the reaction continues at this temperature for 4 h. After the reaction is complete, the triethylamine hydrochloride is removed by filtration, and the filtrate is collected and the solvent is removed by rotary evaporation to obtain 2-(diphenyl phosphate)-4,6-chloro-triazine. This 2-molecule is added to a three-necked flask, and deionized water is added and stirred for 0.5 h. The reaction temperature is adjusted to 90°C, and an aqueous solution of β-alanine (2.7 mol / ml) is added through a constant-pressure dropping funnel. After the addition is complete, the reaction is allowed to proceed for 10 h. After the reaction is complete, the mixture is filtered and washed to obtain a P / N multi-element reactive nylon 66 flame retardant. The structure of the flame retardant is shown in Formula III.

[0053]

[0054]

[0055] The test results show that the melting points of Examples 1-4 and Comparative Examples 1-3 are 220.5℃, 221.2℃, 221.4℃, 240.2℃, 219.8℃, 219.8℃ and 194.8℃, respectively.

[0056] The following uses flame-retardant nylon as an example to test the effect of the flame retardant prepared by the preparation method of the present invention on the flame retardancy and mechanical properties of nylon 66, as shown in Tables 2 and 3, and the standards referenced for the test are shown in Table 1.

[0057] Table 1. Reference Standards for Test Items

[0058] Testing items Test Standards Tensile strength GB / T1040.2-2006 Determination of tensile properties of plastics Bending strength GB / T9341-2008 Determination of Flexural Properties of Plastics Flame retardant properties UL94 Limiting oxygen index GB / T2406.2

[0059] Application Example 1

[0060] The flame retardant prepared in Example 1 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 4% (mass percentage).

[0061] Application Example 2

[0062] The flame retardant prepared in Example 2 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0063] Application Example 3

[0064] The flame retardant prepared in Example 3 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0065] Application Example 4

[0066] The flame retardant prepared in Example 4 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0067] Application Comparative Example 1

[0068] The flame retardant prepared in Comparative Example 1 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0069] Application Comparative Example 2

[0070] The flame retardant prepared in Comparative Example 2 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0071] Application Comparative Example 3

[0072] The flame retardant prepared in Comparative Example 3 was used to prepare flame retardant nylon 66, wherein the flame retardant content was 6% (mass percentage).

[0073] The performance test results of the flame-retardant nylons prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Tables 2 and 3. As can be seen from Tables 2 and 3, the flame retardants prepared in Examples 1-4 and Comparative Examples 1-3 all impart flame retardancy to the nylon resins after application. The flame-retardant grades of the nylons prepared in Examples 1-4 are higher than those prepared in Comparative Examples 1-3. Furthermore, the addition of flame retardants in Examples 1-4 has little impact on the mechanical properties of the nylon resins; in fact, under optimal reaction conditions, the mechanical properties even slightly surpass those of pure nylon 66 resin.

[0074] Table 2 Flame retardant performance test of flame retardant nylon

[0075]

[0076]

[0077] Table 3. Mechanical Properties Test of Flame-Retardant Nylon

[0078]

[0079] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A high-temperature copolymer flame retardant for nylon resin, characterized in that the flame retardant... It has the structure shown in Equation I; Where R is phenyl or naphthyl.

2. The high-temperature copolymer flame retardant for nylon resin as described in claim 1, characterized in that, The R group is benzene or naphthalene.

3. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 1, characterized in that, Flame retardants are prepared in a two-step process using triphenyl phosphite, cyanuric chloride, and terephthalic acid or 1,6-naphthalenedicarboxylic acid as raw materials under nitrogen protection.

4. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 3, characterized in that, The specific steps are as follows: The first step is the preparation of flame retardant intermediates; Under nitrogen protection, triphenyl phosphite, cyanuric chloride, and acetone solvent were added to the reactor. After the reaction was completed, the solvent and by-products were evaporated and rotary evaporated to generate a flame retardant intermediate. The flame retardant intermediate has the structure shown in Formula II. The second step is the preparation of NP-synergistic flame retardants; The flame retardant intermediate prepared in the first step was added dropwise to a solution of terephthalic acid or 1,6-naphthalenedicarboxylic acid, and a pale yellow precipitate was obtained by the reaction. Finally, the solution was filtered to obtain a crude product, which was washed and dried to obtain the NP synergistic flame retardant.

5. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 4, characterized in that, in the first step, the molar ratio of triphenyl phosphite and cyanuric chloride is 1:1 to 1.

4.

6. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 4, characterized in that, in the second step, the molar ratio of the flame retardant intermediate obtained in the first step to terephthalic acid or 1,6-naphthalenedicarboxylic acid is 1 to 2:2.

2.

7. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 4, characterized in that, In the first step, the reaction temperature is 2-8℃ and the reaction time is 1-2 hours.

8. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 4, characterized in that, In the second step, the reaction temperature is 80℃-100℃ and the reaction time is 4-6 hours.

9. The method for preparing a high-temperature resistant copolymer flame retardant for nylon resin as described in claim 4, characterized in that, In the second step, the product is washed and dried with acetone and anhydrous ethanol.

10. The application of the flame retardant as described in claim 1 or the flame retardant prepared by any one of claims 3-9 in the preparation of nylon resin.

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