A bio-based flame retardant and its preparation method and application

Abstract

The present invention relates to a bio-based flame retardant and a preparation method and application thereof. The molecular structural formula of the bio-based flame retardant is: Method: DOPO and allylthiourea are dissolved in solvent I, and reacted at 70-90°C for 20-24h to obtain the bio-based flame retardant, wherein the molar ratio of DOPO to allylthiourea is 1:1; Application: A flame retardant finishing liquid comprises a bio-based flame retardant, dialdehyde and solvent III as described above; after the pH value of the flame retardant finishing liquid is adjusted to 3-5, polyamide 56 fabric is immersed therein, and taken out to obtain flame retardant polyamide 56 fabric. The preparation method of the present invention is simple. After the obtained bio-based flame retardant is applied to finishing polyamide 56 fabric, the polyamide 56 fabric has excellent flame retardant performance and good water washing resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants and relates to a bio-based flame retardant and a preparation method and application thereof. Background Art

[0002] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a highly efficient and green flame retardant, but its poor water solubility, low thermal stability and large molecular rigidity limit its application.

[0003] Currently, there are only a few feasible schemes to use DOPO and its derivatives to prepare flame-retardant and functionalized polyamide fibers.

[0004] Literature 1 (New sustainable flame retardant DOPO-NH-functionalized polyamide 6 and filament yarn [J]. Chemical Engineering Journal, 2021, 426: 130760.) proposed that a DOPO derivative DOPO-A-CLM was synthesized from DOPO and α-amino-ε-caprolactam, and then flame-retardant polyamide 6 fiber was prepared by melt spinning; among them, after adding 10% DOPO-A-CLM, the dripping and burning behaviors of polyamide 6 fiber were suppressed, and self-extinguishing performance was achieved. However, this method cannot effectively suppress molten droplets. Even if 10% of flame retardant is added, molten droplets still exist, and the strength is greatly reduced, by about 54%, which limits its application scenarios.

[0005] Reference 2 (Effect of different flame-retardant bridged dopo derivatives on properties of in situ produced fiber-forming polyamide 6 [J]. Polymers, 2020, 12 (3): 657.) and Reference 3 (New Insights into Antibacterial and Antifungal Properties, Cytotoxicity and Aquatic Ecotoxicity of Flame Retardant PA6 / DOPO-Derivative Nanocomposite Textile Fibers [J]. Polymers, 2021, 13 (6): 905.) prepared functionalized PA6 fibers by introducing PHED (DOPO derivative) into the PA6 main chain during in situ polymerization; among them, the PA6 fiber modified with 15% PHED achieved UL94 V-0 rate, LOI reached 27.8%, and showed excellent antibacterial activity. However, the high addition amount significantly reduced the strength, toughness and elongation of the fiber, the toughness decreased by about 47%, and the fiber was more easily broken.

[0006] Document 4 (Sol-gel coatings from DOPO-alkoxysilanes: Efficacy in fire protection of polyamide 66 textiles [J]. European Polymer Journal, 2020, 125: 109483.) reported two DOPO alkoxysilane-based derivatives (DOPO-GPTMS and DOPO-APTES), which improved the flame retardancy of polyamide 66 fabrics through the sol-gel method. The use of 200 g / L DOPO alkoxysilane derivatives can pass the UL94V-1 level, but the LOI value is only increased from 19.5% to 22.5% or 21.5%, and the washing durability is poor. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a bio-based flame retardant and a preparation method and application thereof.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A bio-based flame retardant with the following molecular structure:

[0010]

[0011] The present invention also provides a method for preparing the bio-based flame retardant as described above, wherein DOPO and allyl thiourea are dissolved in a solvent I, and reacted at 70 to 90° C. for 20 to 24 hours to obtain the bio-based flame retardant, wherein the molar ratio of DOPO to allyl thiourea is 1:1.

[0012] As the preferred technical solution:

[0013] According to the method described above, the preparation process of allyl thiourea is as follows: after mixing ammonia water, solvent II and allyl mustard oil, reacting at 50-60°C for 4-5h, stirring at room temperature for 24h, and obtaining allyl thiourea by recrystallization purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2mol:100mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1. The price of allyl thiourea on the market is relatively high and is not suitable for industrial production. The allyl thiourea prepared by the present invention has a high yield (81.6%) and is easy to operate.

[0014] In the method as described above, solvent I is ethanol or isopropanol, and solvent II is ethanol or isopropanol.

[0015] The present invention also provides a flame retardant finishing liquid, comprising the bio-based flame retardant, dialdehyde and solvent III as described above.

[0016] As the preferred technical solution:

[0017] In the flame retardant finishing liquid as described above, the dialdehyde is glutaraldehyde.

[0018] In the flame retardant finishing liquid as described above, the content of the bio-based flame retardant in the flame retardant finishing liquid is 1.5-4.5wt%, and the content of the dialdehyde is 0.5-1wt%.

[0019] In the flame retardant finishing liquid as described above, the solvent III is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1-4.

[0020] The present invention also provides a use of a flame retardant finishing liquid as described in any one of the above items, wherein the pH value of the flame retardant finishing liquid is adjusted to 3 to 5, polyamide 56 fabric is immersed in the flame retardant finishing liquid, and then taken out to obtain the flame retardant polyamide 56 fabric;

[0021] Dialdehyde can react with the amino groups of polyamide 56 fabric and the amino groups of flame retardant, thereby acting as a cross-linking agent, allowing polyamide 56 and bio-based flame retardant to indirectly undergo chemical cross-linking, thereby improving the bonding strength between the two.

[0022] As the preferred technical solution:

[0023] For the application as described above, the immersion temperature is 70-90°C, the immersion time is 50-70 minutes, and the immersion bath ratio is 1:30-50.

[0024] In the application described above, the LOI of the flame retardant polyamide 56 fabric is above 29%, the damaged length does not exceed 13.9 cm, the number of droplets is 0, the inhibition rate against Escherichia coli is above 98.5%, and the inhibition rate against Staphylococcus aureus is above 97%.

[0025] The principle of the present invention is as follows:

[0026] The bio-based flame retardant of the present invention contains flame retardant elements such as P / N / S. After decomposition, the flame retardant will produce a large amount of non-combustible gases, such as ammonia, carbon dioxide, nitrogen dioxide, etc., thereby diluting the concentration of oxygen; the phosphorus free radicals (PO·, PO 2 ) and sulfur dioxide (SO 2 ) can capture the free radicals (·OH and ·H) required for combustion, thereby quenching the reaction. In this process, the sulfur element improves the quenching effect of the system, and the nitrogen element improves the dilution effect of the system. In addition, DOPO decomposes at high temperature to produce polymetaphosphoric acid, which improves the carbonization ability to a certain extent.

[0027] The synergistic effect of P / N / S effectively improves the flame retardant properties of polyamide 56, and the flame retardant mechanism is a combination of gas phase and solid phase. At the same time, the electron-rich O, N, and S elements in the system can interact with the cell wall of bacteria, further destroying the cell wall, giving the flame retardant polyamide 56 fabric excellent antibacterial properties.

[0028] Beneficial Effects

[0029] (1) The bio-based flame retardant of the present invention is green, environmentally friendly, and low in toxicity. Compared with the prior art, the flame retardant is more efficient;

[0030] (2) The preparation method of the bio-based flame retardant of the present invention is simple;

[0031] (3) The flame retardant finishing liquid of the present invention has extremely high flame retardant efficiency. The self-extinguishing and anti-melting properties of polyamide 56 fabric can be imparted to the fabric by finishing the polyamide 56 fabric with the flame retardant finishing liquid at a relatively low concentration.

[0032] (4) The flame retardant finishing liquid of the present invention is applied to polyamide 56 fabric. The process is simple and the dialdehyde is used to form a covalent bond between the flame retardant and the fabric to improve the water washability of the flame retardant polyamide 56 fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a hydrogen spectrum of the bio-based flame retardant of the present invention;

[0034] Figure 2 This is the infrared spectrum of the bio-based flame retardant of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. 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 fall within the scope limited by the appended claims of the application equally.

[0036] The detection methods of the relevant properties in the following embodiments are as follows:

[0037] LOI is tested according to ASTM D2863-17;

[0038] The damage length is tested according to ASTM D6413-15;

[0039] The number of droplets is tested according to ASTM D2863-17;

[0040] The inhibition rate of Escherichia coli and Staphylococcus aureus was tested with reference to GB / T 20944.3;

[0041] Water washing was carried out according to AATCC 61-2013.

[0042] The manufacturers and brands of the relevant substances in the following examples are as follows:

[0043] Polyamide 56 fabric: The manufacturer is Shanghai Cathay Biotechnology Research and Development Center Co., Ltd., with a weight of 85g / m 2 ; The LOI of polyamide 56 fabric is 26.0%, the damaged length is 15.5 cm, the number of droplets is 2, and the absorbent cotton is ignited;

[0044] DOPO: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., and the brand number is CAS: 35948-25-5;

[0045] Ammonia: The manufacturer is Jiangsu Qiangsheng Functional Chemical Co., Ltd., brand number is CAS: 1336-21-6;

[0046] Allyl mustard oil: The manufacturer is Shanghai McLean Biochemical Co., Ltd., and the brand number is CAS: 1476-23-9.

[0047] Example 1

[0048] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allylthiourea in a molar ratio of 1:1 in a solvent I (specifically ethanol), and reacting at 70° C. for 21 hours to obtain the bio-based flame retardant;

[0049] Among them, the mass ratio of DOPO to solvent I is 1:7; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 50°C for 5 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0050] The final bio-based flame retardant, such as Figures 1-2 As shown, the molecular structure is:

[0051] A flame retardant finishing liquid is composed of the bio-based flame retardant prepared by the above method, dialdehyde and solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 2wt%, and the content of the dialdehyde is 0.5wt%; wherein the dialdehyde is glutaraldehyde, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:4.

[0052] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 4, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 80°C, the immersion time is 60 minutes, and the bath ratio is 1:30.

[0053] The final flame retardant polyamide 56 fabric had a LOI of 29.4%, a damaged length of 13.5 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 98.8%, and an inhibition rate against Staphylococcus aureus of 97.3%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 27.2%, the damaged length was 14.5 cm, and the droplet number was 0.

[0054] Example 2

[0055] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allyl thiourea in a molar ratio of 1:1 in a solvent I (specifically isopropanol), and reacting at 90° C. for 22 hours to obtain the bio-based flame retardant;

[0056] Among them, the mass ratio of DOPO to solvent I is 1:8; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 52°C for 4.8 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0057] The final bio-based flame retardant has the following molecular structure:

[0058] A flame retardant finishing liquid is composed of the bio-based flame retardant prepared by the above method, dialdehyde and solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 3wt%, and the content of the dialdehyde is 1wt%; wherein the dialdehyde is terephthalaldehyde, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:3.

[0059] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 3.5, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 85°C, the immersion time is 65 minutes, and the bath ratio is 1:50.

[0060] The final flame retardant polyamide 56 fabric had a LOI of 29.8%, a damaged length of 12.5 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 99.5%, and an inhibition rate against Staphylococcus aureus of 97.7%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 27.5%, the damaged length was 13.9 cm, and the droplet number was 0.

[0061] Example 3

[0062] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allylthiourea in a molar ratio of 1:1 in a solvent I (specifically ethanol), and reacting at 75° C. for 20 hours to obtain the bio-based flame retardant;

[0063] Among them, the mass ratio of DOPO to solvent I is 1:10; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 54°C for 4.6 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0064] The final bio-based flame retardant has the following molecular structure:

[0065] A flame retardant finishing liquid is composed of the bio-based flame retardant prepared by the above method, dialdehyde and solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 2.5wt%, and the content of the dialdehyde is 0.6wt%; wherein the dialdehyde is furan dicarboxaldehyde, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:1.

[0066] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 4.5, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 70°C, the immersion time is 50 minutes, and the bath ratio is 1:35.

[0067] The final flame retardant polyamide 56 fabric had a LOI of 29.6%, a damaged length of 13 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 99.2%, and an inhibition rate against Staphylococcus aureus of 97.6%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 27.7%, the damaged length was 14.1 cm, and the droplet number was 0.

[0068] Example 4

[0069] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allyl thiourea in a molar ratio of 1:1 in a solvent I (specifically isopropanol), and reacting at 85° C. for 24 hours to obtain the bio-based flame retardant;

[0070] Among them, the mass ratio of DOPO to solvent I is 1:9; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 56°C for 4.4 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0071] The final bio-based flame retardant has the following molecular structure:

[0072] A flame retardant finishing liquid is composed of the bio-based flame retardant prepared by the above method, dialdehyde and solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 3.5wt%, and the content of the dialdehyde is 0.7wt%; wherein the dialdehyde is glutaraldehyde, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:4.

[0073] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 4.2, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 75°C, the immersion time is 70 minutes, and the bath ratio is 1:40.

[0074] The final flame retardant polyamide 56 fabric had an LOI of 30%, a damaged length of 12.2 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 99.7%, and an inhibition rate against Staphylococcus aureus of 98%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 28.3%, the damaged length was 13.6 cm, and the droplet number was 0.

[0075] Example 5

[0076] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allyl thiourea in a molar ratio of 1:1 in a solvent I (specifically ethanol), and reacting at 80° C. for 23 hours to obtain the bio-based flame retardant;

[0077] Among them, the mass ratio of DOPO to solvent I is 2:15; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 58°C for 4.2 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0078] The final bio-based flame retardant has the following molecular structure:

[0079] A flame retardant finishing liquid is composed of a bio-based flame retardant prepared by the above method, a dialdehyde and a solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 1.5wt%, and the content of the dialdehyde is 0.8wt%; wherein the dialdehyde is malondialdehyde, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:2.5.

[0080] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 3, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 80°C, the immersion time is 55 minutes, and the bath ratio is 1:45.

[0081] The final flame retardant polyamide 56 fabric had a LOI of 29%, a damaged length of 13.9 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 98.5%, and an inhibition rate against Staphylococcus aureus of 97%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 27.0%, the damaged length was 14.8 cm, and the droplet number was 0.

[0082] Example 6

[0083] A method for preparing a bio-based flame retardant, the specific process is: dissolving DOPO and allyl thiourea in a molar ratio of 1:1 in a solvent I (specifically isopropanol), and reacting at 88° C. for 20.5 hours to obtain the bio-based flame retardant;

[0084] Among them, the mass ratio of DOPO to solvent I is 2:17; the preparation process of allyl thiourea is: after mixing ammonia water, solvent II (specifically ethanol) and allyl mustard oil, react at 60°C for 4 hours, and then stir at room temperature for 24 hours, and obtain allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to ethanol is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:1.

[0085] The final bio-based flame retardant has the following molecular structure:

[0086] A flame retardant finishing liquid is composed of the bio-based flame retardant prepared by the above method, dialdehyde and solvent III; the content of the bio-based flame retardant in the flame retardant finishing liquid is 4.5wt%, and the content of the dialdehyde is 0.9wt%; wherein the dialdehyde is glyoxal, and the solvent III is a mixture of ethanol and water in a volume ratio of 1:3.5.

[0087] An application of a flame retardant finishing liquid. After the pH value of the flame retardant finishing liquid is adjusted to 5, polyamide 56 fabric is immersed in the liquid and taken out to obtain the flame retardant polyamide 56 fabric. The immersion temperature is 90°C, the immersion time is 60 minutes, and the bath ratio is 1:30.

[0088] The final flame retardant polyamide 56 fabric had a LOI of 30.5%, a damaged length of 11.1 cm, a droplet number of 0, an inhibition rate against Escherichia coli of 99.9%, and an inhibition rate against Staphylococcus aureus of 98.2%. After 25 washes, the LOI of the flame retardant polyamide 56 fabric was 28.5%, the damaged length was 13.2 cm, and the droplet number was 0.

Claims

1. A bio-based flame retardant, It is characterized in that The molecular structure is as follows:

2. A method for preparing a bio-based flame retardant as claimed in claim 1, It is characterized in that After DOPO and allylthiourea are dissolved in solvent I, the mixture is reacted at 70 to 90° C. for 20 to 24 hours to obtain a bio-based flame retardant, wherein the molar ratio of DOPO to allylthiourea is 1:

1.

3. The method according to claim 2, It is characterized in that The preparation process of allyl thiourea is as follows: after mixing ammonia water, solvent II and allyl mustard oil, reacting at 50-60° C. for 4-5 hours, stirring at room temperature for 24 hours, and obtaining allyl thiourea by recrystallization and purification, wherein the molar volume ratio of ammonia water to solvent II is 0.2 mol:100 mL, and the molar ratio of ammonia water to allyl mustard oil is 1:

1.

4. The method according to claim 3, It is characterized in that Solvent I is ethanol or isopropanol, and solvent II is ethanol or isopropanol.

5. A flame retardant finishing liquid, It is characterized in that The method comprises the bio-based flame retardant as claimed in claim 1, a dialdehyde and a solvent III.

6. A flame retardant finishing liquid according to claim 5, It is characterized in that The dialdehyde is glutaraldehyde.

7. A flame retardant finishing liquid according to claim 5, It is characterized in that The content of the bio-based flame retardant in the flame retardant finishing liquid is 1.5-4.5wt%, and the content of the dialdehyde is 0.5-1wt%.

8. A flame retardant finishing liquid according to claim 5, It is characterized in that Solvent III is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1-4.

9. Use of a flame retardant finishing liquid as claimed in any one of claims 5 to 8, It is characterized in that After the pH value of the flame retardant finishing liquid is adjusted to 3-5, the polyamide 56 fabric is immersed in it and taken out to obtain the flame retardant polyamide 56 fabric.

10. The use according to claim 9, It is characterized in that The immersion temperature is 70-90° C., the immersion time is 50-70 min, and the immersion bath ratio is 1:30-50.

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