A high-strength flame-retardant nylon composition and a method for preparing the same

Abstract

The present application relates to the technical field of flame-retardant nylon composition, and particularly relates to a high-strength flame-retardant nylon composition and a preparation method thereof, which comprises the following raw materials in parts by mass: nylon resin 100 parts, composite flame retardant 5-10 parts, toughening agent 10-15 parts, and modified glass fiber 20-30 parts; the composite flame retardant is formed by mixing self-made nitrogen-phosphorus flame retardant and tannic acid at a mass ratio of 1:(0.2-0.3); the preparation method of the self-made nitrogen-phosphorus flame retardant comprises the following steps: A1: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, then refluxing at 175 DEG C for 5-7 h, naturally cooling to room temperature, and obtaining a DOPO-ITA reaction solution; A2: adding pentaerythritol tetranitrate and EDC into DMF, stirring and mixing at 60 DEG C, then adding the DOPO-ITA reaction solution dropwise, stirring and reacting at 70-90 DEG C for 3-5 h, removing the solvent by rotary evaporation, drying, and obtaining the self-made nitrogen-phosphorus flame retardant. The nylon composition prepared by the present application has excellent flame-retardant performance, the oxygen index is higher than 35%, the vertical combustion test reaches V-0, and the nylon composition has good mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant nylon composition, in particular to a high-strength flame-retardant nylon composition and a preparation method thereof. BACKGROUND

[0002] Nylon, also known as polyamide fiber, is a thermoplastic resin containing repeating amide groups (-NHCO-) in the molecular chain, and is the first synthetic fiber in the world and one of the most widely used materials in the world. However, nylon is a flammable material, and its flammability may cause safety hazards under high temperature or fire. Therefore, improving the flame-retardant performance of nylon material is an important direction of its modification treatment.

[0003] At present, the flame retardants used to improve the flame-retardant performance of nylon include inorganic flame retardants, organic phosphorus flame retardants and halogen flame retardants, etc., but there are generally problems such as unstable flame-retardant effect, decrease of mechanical properties of nylon and poor environmental friendliness. Therefore, it is of great significance to develop a new type of intumescent flame retardant for application in nylon material, further improve its flame-retardant performance and maintain its good mechanical properties. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a high-strength flame-retardant nylon composition and a preparation method thereof. The self-made nitrogen-phosphorus flame retardant and the tannic acid combined flame retardant can effectively improve the flame-retardant and fire-resistant performance of nylon, and the prepared nylon composition has good mechanical properties, and the bending strength is higher than 120 MPa.

[0005] Based on the above purpose, the present application provides a high-strength flame-retardant nylon composition, which comprises the following mass parts of raw materials: nylon resin 100 parts, composite flame retardant 5-10 parts, toughening agent 10-15 parts, modified glass fiber 20-30 parts;

[0006] The composite flame retardant is mixed by self-made nitrogen-phosphorus flame retardant and tannic acid in a mass ratio of 1:(0.2-0.3);

[0007] The preparation method of the self-made nitrogen-phosphorus flame retardant comprises the following steps:

[0008] A1: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, then refluxing at 175℃ for 5-7h, and naturally cooling to room temperature to obtain a DOPO-ITA reaction solution;

[0009] The synthesis route of DOPO-ITA is shown in formula I:

[0010]

[0011] A2: pentamethylene, EDC is added in DMF, after stirring and mixing at 60 DEG C, drop DOPO-ITA reaction solution, stirring at 70-90 DEG C for 3-5h, remove the solvent by rotary evaporation, dry, get self-made nitrogen phosphorus flame retardant.

[0012] The synthesis route of the self-made nitrogen phosphorus flame retardant is shown in formula II:

[0013]

[0014] Further, the nylon resin is one or both of nylon 6 resin or nylon 66 resin.

[0015] Further, the use amount ratio of DOPO, itaconic acid, 1,4-dioxane, pentamethylene, EDC and DMF is 1mol:1mol:900mL:0.25mol:(0.01-0.02)mol:100mL.

[0016] Further, the toughening agent is one or more of ethylene-octene copolymer grafted maleic anhydride, ethylene-vinyl acetate copolymer grafted maleic anhydride and ethylene-1-butene copolymer.

[0017] Further, the preparation method of the modified glass fiber is as follows: glass fiber is added into deionized water, 3-isocyanate propyl trimethoxysilane is added dropwise, stirring at 30-50 DEG C for 2-3h, then filtering and drying to obtain the modified glass fiber.

[0018] Further, the use amount ratio of glass fiber, deionized water and 3-isocyanate propyl trimethoxysilane is 1g:(1.3-1.5)mL:(0.1-0.15)g.

[0019] Further, the diameter of the glass fiber is 5-7μm, and the length is 2-3mm.

[0020] The application also provides a preparation method of the high-strength flame-retardant nylon composition.

[0021] After mixing the nylon resin, the composite flame retardant and the toughening agent uniformly, the double screw extruder is added through the main feeding port, the modified glass fiber is added into the double screw extruder through the side feeding port, and the high-strength flame-retardant nylon composition is obtained after melting blending, extruding granulation and drying.

[0022] Further, the working temperature of each zone of the double screw extruder is as follows: the first zone is 230-250 DEG C, the second zone is 240-270 DEG C, the third zone is 245-275 DEG C, and the fourth zone is 250-280 DEG C; and the screw rotation speed of the double screw extruder is 330-450rpm.

[0023] The application has the following beneficial effects:

[0024] The nylon composition prepared by the application has excellent flame retardant performance, the oxygen index is higher than 35%, the vertical combustion test reaches V-0, and has good mechanical performance, the bending strength is higher than 120 MPa.

[0025] The application further strengthens the flame retardant effect by the synergistic effect of the self-made nitrogen-phosphorus flame retardant and tannic acid, and the flame retardant effect is stable and environment-friendly. The self-made nitrogen-phosphorus flame retardant is prepared by the addition reaction of DOPO and itaconic acid to generate DOPO-ITA, and then the amide reaction of DOPO-ITA and pentaerythritol to generate the new nitrogen-phosphorus synergistic flame retardant. The flame retardant is a star-shaped flame retardant structure with pentaerythritol as the core and DOPO-ITA as the extended arm. When burning, a large amount of nitrogen-containing non-combustible gas, H2O(g) and the like are generated, and a large amount of heat is absorbed. At the same time, the tannic acid promotes the formation of a dense carbon layer on the surface of the nylon polymer, which blocks the oxygen from entering the interior of the burning material, so as to stop the combustion reaction. In addition, the DOPO-ITA molecule has a biphenyl ring and a phenanthrene ring structure, which is introduced into the nylon composition, so as to improve the mechanical strength of the nylon composition and improve the thermal stability thereof. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below with specific examples.

[0027] The application provides a preparation method of the high-strength flame-retardant nylon composition of an embodiment, which comprises the following raw materials in parts by mass:

[0028] S1: preparing the self-made nitrogen-phosphorus flame retardant:

[0029] S101: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, and then refluxing at 175 DEG C for 5-7 h, and then naturally cooling to room temperature to obtain a DOPO-ITA reaction solution;

[0030] The synthesis route of DOPO-ITA is shown in formula I:

[0031]

[0032] S102: adding pentaerythritol and EDC into DMF, stirring and mixing at 60 DEG C, adding the DOPO-ITA reaction solution dropwise, stirring and reacting at 70-90 DEG C for 3-5 h, removing the solvent by rotary evaporation and drying to obtain the self-made nitrogen-phosphorus flame retardant;

[0033] The synthesis route of the self-made nitrogen-phosphorus flame retardant is shown in formula II:

[0034]

[0035] The amount ratio of the DOPO, itaconic acid, 1,4-dioxane, pentaerythritol, EDC, DMF is 1 mol:1 mol:900 mL:0.25 mol:(0.01-0.02) mol:100 mL;

[0036] The DOPO and itaconic acid are first added to generate DOPO-ITA, and then the DOPO-ITA is further reacted with pentaerythritol to generate a novel nitrogen-phosphorus synergistic flame retardant. The flame retardant is a star-shaped flame retardant structure with pentaerythritol as the core and DOPO-ITA as the extended arm. When burning, a large amount of nitrogen-containing non-combustible gas, H2O(g), and the like are generated, and a large amount of heat is absorbed. At the same time, phosphoric acid is formed on the surface of the DOPO-ITA molecule nylon polymer, which promotes the formation of a dense carbon layer on the surface of the polymer, thereby preventing the combustion reaction. In addition, the DOPO-ITA molecule has a biphenyl ring and a phenanthrene ring structure, which is introduced into the nylon composition, thereby improving the mechanical strength of the nylon composition and improving the thermal stability thereof.

[0037] S2: preparing a composite flame retardant: uniformly mixing the self-made nitrogen-phosphorus flame retardant and tannic acid at a mass ratio of 1:(0.2-0.3) to obtain a composite flame retardant; the self-made nitrogen-phosphorus flame retardant and tannic acid are combined to form a composite flame retardant, and the two synergistically enhance the flame retardant effect;

[0038] S3: preparing modified glass fiber: adding glass fiber with a diameter of 5-7 μm and a length of 2-3 mm into deionized water, and adding 3-isocyanate propyl trimethoxysilane dropwise, stirring at 30-50°C for 2-3 h, and then filtering and drying to obtain modified glass fiber; the amount ratio of the glass fiber, deionized water, and 3-isocyanate propyl trimethoxysilane is 1 g:(1.3-1.5) mL:(0.1-0.15) g;

[0039] The glass fiber is modified by 3-isocyanate propyl trimethoxysilane, which improves the compatibility of the glass fiber in the nylon system, stably combines the glass fiber in the nylon system, and further provides the strength of the nylon composition;

[0040] S4: preparing a high-strength flame-retardant nylon composition: uniformly mixing 100 parts of nylon resin, 5-10 parts of a composite flame retardant, and 10-15 parts of a toughening agent, adding the mixture into a twin-screw extruder through a main feeding port, and adding 20-30 parts of modified glass fiber into the twin-screw extruder through a side feeding port, and then performing melt blending, extruding, granulating, and drying to obtain a high-strength flame-retardant nylon composition;

[0041] The working temperature of each zone of the double screw extruder is: zone 1 230-250℃, zone 2 240-270℃, zone 3 245-275℃, zone 4 250-280℃; the screw rotation speed of the double screw extruder is 330-450rpm;

[0042] Further, the toughening agent is one or more of ethylene-octene copolymer grafted maleic anhydride, ethylene-vinyl acetate copolymer grafted maleic anhydride, and ethylene-1-butene copolymer.

[0043] Example 1

[0044] A preparation method of a high-strength flame-retardant nylon composition, comprising the following raw materials by mass fraction:

[0045] S1: preparing a self-made nitrogen-phosphorus flame retardant:

[0046] S101: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, then refluxing at 175℃ for 5h, naturally cooling to room temperature, to obtain a DOPO-ITA reaction solution;

[0047] S102: adding pentaerythritol and EDC into DMF, stirring and mixing at 60℃, then adding the DOPO-ITA reaction solution dropwise, stirring and reacting at 70℃ for 3h, removing the solvent by rotary evaporation and drying, to obtain a self-made nitrogen-phosphorus flame retardant;

[0048] The amount ratio of the DOPO, itaconic acid, 1,4-dioxane, pentaerythritol, EDC, and DMF is 1mol:1mol:900mL:0.25mol:0.01mol:100mL;

[0049] S2: preparing a composite flame retardant: uniformly mixing the self-made nitrogen-phosphorus flame retardant and tannic acid at a mass ratio of 1:0.2, to obtain a composite flame retardant;

[0050] S3: preparing modified glass fiber: adding glass fiber with a diameter of 5μm and a length of 2mm into deionized water, adding 3-isocyanate propyl trimethoxysilane dropwise, stirring and reacting at 30℃ for 2h, then filtering and drying, to obtain modified glass fiber; the amount ratio of the glass fiber, deionized water, and 3-isocyanate propyl trimethoxysilane is 1g:1.3mL:0.1g;

[0051] S4: preparing a high-strength flame-retardant nylon composition: uniformly mixing 100 parts of nylon 6 resin, 5 parts of composite flame retardant, and 10 parts of toughening agent ethylene-octene copolymer grafted maleic anhydride, then adding into a double screw extruder through a main feeding port, and adding 20 parts of modified glass fiber into the double screw extruder from a side feeding port, to obtain a high-strength flame-retardant nylon composition after melt blending, extrusion granulation, and drying;

[0052] The working temperature of each zone of the double screw extruder is: 240℃ for the first zone, 260℃ for the second zone, 265℃ for the third zone, and 270℃ for the fourth zone; the screw rotation speed of the double screw extruder is 400rpm.

[0053] Example 2

[0054] A preparation method of a high-strength flame-retardant nylon composition, comprising the following raw materials by mass fraction:

[0055] S1: preparing a self-made nitrogen-phosphorus flame retardant:

[0056] S101: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, then refluxing at 175℃ for 7h, and naturally cooling to room temperature to obtain a DOPO-ITA reaction solution;

[0057] S102: adding pentaerythritol and EDC into DMF, stirring and mixing at 60℃, then adding the DOPO-ITA reaction solution dropwise, stirring and reacting at 90℃ for 5h, removing the solvent by rotary evaporation and drying to obtain a self-made nitrogen-phosphorus flame retardant;

[0058] The amount ratio of the DOPO, itaconic acid, 1,4-dioxane, pentaerythritol, EDC, and DMF is 1mol:1mol:900mL:0.25mol:0.02mol:100mL;

[0059] S2: preparing a composite flame retardant: uniformly mixing the self-made nitrogen-phosphorus flame retardant and tannic acid at a mass ratio of 1:0.3 to obtain a composite flame retardant;

[0060] S3: preparing modified glass fiber: adding glass fiber with a diameter of 7μm and a length of 3mm into deionized water, adding 3-isocyanate propyl trimethoxysilane dropwise, stirring and reacting at 50℃ for 3h, then filtering and drying to obtain modified glass fiber; the amount ratio of the glass fiber, deionized water, and 3-isocyanate propyl trimethoxysilane is 1g:1.5mL:0.15g;

[0061] S4: preparing a high-strength flame-retardant nylon composition: uniformly mixing 100 parts of nylon 66 resin, 10 parts of a composite flame retardant, and 15 parts of a toughening agent ethylene-vinyl acetate copolymer grafted maleic anhydride, then adding them into a double screw extruder through a main feeding port, and adding 20-30 parts of modified glass fiber into the double screw extruder from a side feeding port, and after melting blending, extruding, granulating, and drying, a high-strength flame-retardant nylon composition is obtained;

[0062] The working temperature of each zone of the double screw extruder is: 250℃ for the first zone, 270℃ for the second zone, 275℃ for the third zone, and 280℃ for the fourth zone; the screw rotation speed of the double screw extruder is 450rpm.

[0063] Comparative Example 1 is the same as Example 1, except that Comparative Example 1 uses tannic acid instead of the composite flame retardant.

[0064] Comparative Example 2 is the same as Example 1, except that Comparative Example 2 uses a self-made nitrogen-phosphorus flame retardant instead of the composite flame retardant.

[0065] Comparative Example 3 is the same as Example 1, except that the composite flame retardant is a mixture of DOPO-ITA and tannic acid in a mass ratio of 1:0.2; the DOPO-ITA is prepared by removing the solvent from the DOPO-ITA reaction solution by rotary evaporation and drying.

[0066] The nylon compositions prepared in Examples 1-2 and Comparative Examples 1-3 are injection molded into flame-retardant samples, and the flame-retardant performance is tested.

[0067] The oxygen index of the nylon compositions prepared in Examples 1-2 and Comparative Examples 1-3 is determined according to GB / T2406.2-2009 "Determination of Burning Behavior of Plastics by Oxygen Index Method", and the sample size is 130mm*8mm*4mm.

[0068] The vertical burning of the nylon compositions prepared in Examples 1-2 and Comparative Examples 1-3 is performed according to UL-94-2009, and the sample size is 120mm*12mm*3mm.

[0069] The results of the flame-retardant performance test are shown in Table 1.

[0070] Table 1

[0071] Group Oxygen index / % Vertical burning Example 1 36.2 V-0 Example 2 39.4 V-0 Comparative Example 1 26.8 V-2 Comparative Example 2 31.6 V-1 Comparative Example 3 31.1 V-1

[0072] As shown in Table 1, the flame-retardant performance of the nylon compositions prepared in Examples 1-2 is significantly better than that of Comparative Examples 1-3, which proves that the use of the self-made nitrogen-phosphorus flame retardant and tannic acid in the composite flame retardant can effectively improve the flame-retardant and fire-resistant performance of the nylon, and the composite flame retardant system contains a large number of -OH and -COOH groups which can crosslink with the -NCO in the modified glass fiber and the terminal amino group in the nylon resin, so that the nylon composition maintains good mechanical properties, and the flexural strength is higher than 120MPa.

[0073] It should be understood by those skilled in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest the scope of the present application (including the claims) is limited to these examples; under the concept of the present application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for the sake of brevity.

[0074] The present application is intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any and all such alternatives, modifications, equivalents, improvements and the like are intended to be encompassed by the present application.

Claims

1. A high-strength flame-retardant nylon composition characterized in that, The composition comprises the following raw materials by mass: 100 parts of nylon resin, 5-10 parts of composite flame retardant, 10-15 parts of toughening agent, and 20-30 parts of modified glass fiber. The composite flame retardant is prepared by mixing self-made nitrogen-phosphorus flame retardant and tannic acid at a mass ratio of 1:(0.2-0.3). The preparation method of the self-made nitrogen-phosphorus flame retardant comprises the following steps: A1: adding DOPO and itaconic acid into 1,4-dioxane, stirring and dissolving, then refluxing at 175 DEG C for 5-7 hours, and naturally cooling to room temperature to obtain a DOPO-ITA reaction solution; A2: adding pentaerythritol and EDC into DMF, stirring and mixing at 60 DEG C, then adding the DOPO-ITA reaction solution dropwise, stirring and reacting at 70-90 DEG C for 3-5 hours, removing the solvent by rotary evaporation, and drying to obtain the self-made nitrogen-phosphorus flame retardant.

2. A high-strength flame-retardant nylon composition according to claim 1, characterized in that, The nylon resin is one or both of nylon 6 resin and nylon 66 resin.

3. A high-strength flame-retardant nylon composition according to claim 1, wherein The amount ratio of the DOPO, itaconic acid, 1,4-dioxane, pentaerythritol, EDC, and DMF is 1 mol:1 mol:900 mL:0.25 mol:(0.01-0.02) mol:100 mL.

4. A high-strength flame-retardant nylon composition according to claim 1, wherein The toughening agent is one or more of ethylene-octene copolymer grafted maleic anhydride, ethylene-vinyl acetate copolymer grafted maleic anhydride, and ethylene-1-butene copolymer.

5. A high-strength flame-retardant nylon composition according to claim 1, wherein The preparation method of the modified glass fiber is as follows: adding glass fiber into deionized water, adding 3-isocyanate propyl trimethoxysilane dropwise, stirring and reacting at 30-50 DEG C for 2-3 hours, then filtering and drying to obtain the modified glass fiber.

6. A high-strength flame-retardant nylon composition according to claim 5, wherein The amount ratio of the glass fiber, deionized water, and 3-isocyanate propyl trimethoxysilane is 1 g:(1.3-1.5) mL:(0.1-0.15) g.

7. A high-strength flame-retardant nylon composition according to claim 5, wherein The diameter of the glass fiber is 5-7 microns, and the length is 2-3 mm.

8. A process for the preparation of a high-strength flame-retardant nylon composition according to any one of claims 1-7, characterized in that, The method comprises the following steps: After the nylon resin, the composite flame retardant, and the toughening agent are uniformly mixed, they are added into a double-screw extruder through a main feeding port, and the modified glass fiber is added into the double-screw extruder through a side feeding port, so that a high-strength flame-retardant nylon composition is obtained after melting blending, extruding, granulating, and drying.

9. A process for the preparation of a high-strength flame-retardant nylon composition according to claim 8, characterized in that, The working temperature of each zone of the double-screw extruder is as follows: 230-250 DEG C for the first zone, 240-270 DEG C for the second zone, 245-275 DEG C for the third zone, and 250-280 DEG C for the fourth zone; and the screw rotation speed of the double-screw extruder is 330-450 rpm.

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