Flame retardant particles for plastic woven mesh and preparation method thereof

Abstract

The invention discloses flame-retardant particles for plastic woven mesh cloth and a preparation method thereof, belonging to the technical field of plastic woven cloth preparation, and comprising the following steps: step S1, hydrophobic treatment of a modified intumescent flame-retardant system; step S2, adding the hydrophobic modified intumescent flame-retardant system, γ-aminopropyltriethoxysilane and a modified synergist into a mixer and uniformly mixing them, placing them into a screw extruder for melt extrusion, and then cooling, drying and pelletizing to obtain the flame-retardant particles for the plastic woven mesh cloth; the invention uses octadecyl methacrylate to perform hydrophobic treatment on the surface of the modified intumescent flame-retardant system, effectively avoiding its hygroscopic performance, and improving the compatibility of the flame-retardant particles with a base material; in addition, the introduction of the modified synergist not only improves the catalytic carbonization efficiency during combustion and enhances the flame-retardant performance, but also the honeycomb pores on the surface can absorb small molecular gases released during combustion and reduce the release of toxic gases.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic woven cloth preparation, and in particular relates to flame retardant particles for plastic woven mesh cloth and a preparation method thereof. Background Art

[0002] Plastic woven mesh is made of polyethylene or polypropylene, and is woven into a cloth-like material by warp and weft yarns. It is widely used in agriculture, construction, transportation and other fields because of its light weight, corrosion resistance and easy processing. However, since its main component is organic polymer, it has a low limiting oxygen index value and is extremely easy to burn. In addition, it is accompanied by severe dripping during combustion, causing secondary fires and bringing serious harm to life and property.

[0003] In the prior art, intumescent flame retardants are usually used when preparing plastic woven mesh. Intumescent flame retardants not only have good flame retardant properties, but also have low toxicity and environmental protection characteristics compared to halogen flame retardants. However, intumescent flame retardants have strong hygroscopicity, are prone to alcoholysis, and have poor compatibility with base materials such as polypropylene or polyethylene, resulting in the intumescent flame retardant being easily migrated and precipitated from the matrix at high temperatures. In addition, the amount of intumescent flame retardant added is large, which reduces the mechanical properties of the plastic woven mesh and limits its application in the flame retardancy of plastic woven mesh. Therefore, how to improve the hygroscopicity of the intumescent flame retardant and improve its compatibility in polymers while improving the flame retardant efficiency of the intumescent flame retardant is a technical problem that needs to be solved at present. Summary of the invention

[0004] The object of the present invention is to provide a flame retardant particle for plastic woven mesh and a preparation method thereof, so as to solve the problems in the background technology.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for preparing flame-retardant particles for plastic woven mesh cloth comprises the following steps:

[0007] Step S1: hydrophobic treatment of modified intumescent flame retardant system:

[0008] Add octadecyl methacrylate to anhydrous ethanol, stir to dissolve, add the modified intumescent flame retardant system, mix evenly, stir to react at 65-70° C. for 2-4 hours, cool, filter, wash and dry to obtain a hydrophobic modified intumescent flame retardant system;

[0009] Step S2: Preparation of flame retardant particles:

[0010] The hydrophobically modified intumescent flame retardant system, γ-aminopropyl triethoxysilane and the modified synergist are added into a mixer and uniformly mixed, and then placed into a screw extruder for melt extrusion, and then cooled, dried and pelletized to obtain flame retardant particles for plastic woven mesh cloth;

[0011] Octadecaned methacrylate is used as a hydrophobic modification agent and is grafted onto the surface of a modified intumescent flame retardant system by an in-situ polymerization method. A firm hydrophobic coating layer is formed on the surface of the modified intumescent flame retardant system, which reduces the hygroscopicity of the modified intumescent flame retardant system and effectively improves the compatibility and dispersibility of the flame retardant particles in polypropylene or polyethylene plastic base materials.

[0012] Among them, the usage ratio of anhydrous ethanol, octadecyl methacrylate and modified intumescent flame retardant system in step S1 is 200mL: 5.2-7.8g: 52-55g; the usage ratio of hydrophobic modified intumescent flame retardant system, γ-aminopropyltriethoxysilane and modified synergist in step S2 is 48-50g: 0.2-0.6mL: 2.89-4.13g.

[0013] Furthermore, the modified intumescent flame retardant system is prepared by the following steps:

[0014] A1. Add cyanuric chloride to an acetone solution with a concentration of 90wt%, stir and mix, add diethanolamine dropwise at 0-5°C, mix evenly, add 34.6% of the total amount of sodium hydroxide solution, stir and react for 3-4h, then heat to 45-50°C, add piperazine acetone solution dropwise, mix evenly, then add the remaining sodium hydroxide solution, react at 80°C for 6h, filter, wash and dry to obtain a modified triazine derivative;

[0015] A2. Add the modified triazine derivative to deionized water, heat to 130°C while stirring, add ammonium polyphosphate after it reaches a molten state, continue stirring and reacting for 3-4 hours, cool, grind, and obtain a modified intumescent flame retardant system.

[0016] Among them, cyanuric chloride and piperazine are the main chains, and diethanolamine is the side chain. A modified triazine derivative containing a polyhydroxy structure is obtained through a nucleophilic substitution reaction. The modified triazine derivative, as a triazine macromolecular carbonizing agent, has excellent carbonizing performance. In a molten state, it is blended with ammonium polyphosphate with good flame retardant properties and combined through hydrogen bonds to obtain a modified intumescent flame retardant system.

[0017] Furthermore, the dosage ratio of the acetone solution, cyanuric chloride, diethanolamine, sodium hydroxide solution and piperazine acetone solution is 250mL:18.4-19.2g:9.7-10.4mL:50mL:40mL; the concentration of the sodium hydroxide solution is 19.4-20.2wt%; and the concentration of the piperazine acetone solution is 0.21-0.23g / mL.

[0018] Furthermore, the usage ratio of the deionized water, the modified triazine derivative and the ammonium polyphosphate is 8 mL: 7.5-9.6 g: 38.4-42.5 g.

[0019] Further, the modified synergist is prepared by the following steps:

[0020] Add the pretreated molecular sieve to deionized water, stir and disperse, add lanthanum chloride aqueous solution at 85-90° C., mix evenly, adjust the pH value to 4.5-5.0 with hydrochloric acid, and then stir and react at 85-90° C. for 1-2 hours, filter, wash, and dry, place in diethylene glycol dimethyl ether, mix evenly, add boric acid, continue to react at 120-130° C. for 5 hours, and finally filter, wash, and dry to obtain a modified synergist;

[0021] Among them, the pretreated molecular sieve is a 4A molecular sieve that is ground into powder and then passed through a 200-mesh standard sieve. The 4A molecular sieve has high surface acidity and good ion exchange performance. When reacting with lanthanum chloride, metallic lanthanum can be doped on the surface of the pretreated molecular sieve by ion exchange, further improving the acidity of the surface of the modified synergist and the catalytic carbonization efficiency. Then, the surface grafting method is used to graft boron on the surface of the pretreated molecular sieve to obtain a modified synergist containing metallic lanthanum and boron atoms.

[0022] Furthermore, the dosage ratio of the deionized water, the pretreated molecular sieve, the lanthanum chloride aqueous solution, diethylene glycol dimethyl ether and boric acid is 200 mL: 10-11 g: 2-2.5 mL: 100 mL: 0.56 g; the concentration of the lanthanum chloride aqueous solution is 0.25 g / mL; and the concentration of the hydrochloric acid is 3.75 wt%.

[0023] The invention discloses flame retardant particles for plastic woven mesh cloth, which are prepared by the above preparation method.

[0024] Beneficial effects of the present invention:

[0025] The flame retardant particles of the present invention contain long alkane chains with hydrophobic properties on their surfaces, which effectively improve their compatibility and dispersibility in polymer base materials such as polypropylene or polyethylene, and enhance the interfacial bonding force between the flame retardant particles and polymer molecules. In addition, the flame retardant particles of the present invention also contain a modified intumescent flame retardant system and a modified synergist compounded therewith. When the plastic woven mesh encounters a heat source and burns, the modified intumescent flame retardant system generates phosphorus-containing free radicals when heated, quenches the active free radicals generated during combustion, and effectively inhibits the chain reaction of combustion. At the same time, the modified triazine derivatives in the modified intumescent flame retardant system act as carbonizing agents, which can react with phosphoric acid generated by decomposition during combustion to form a melt, and the non-combustible gases such as ammonia generated by the decomposition of ammonium ions can cause the melt to expand and dehydrate, and finally form an intumescent carbon layer, which prevents the release of combustible gases and heat to the substrate surface, thereby improving the flame retardancy of the plastic woven mesh.

[0026] At the same time, the surface acidity of the modified synergist of the present invention is high, and it can act as a solid acid to catalyze the carbon cation reaction when the matrix burns, and improve the catalytic efficiency under the action of metal lanthanum, so as to promote the cross-linking of the matrix and the modified intumescent flame retardant system to form a dense residual carbon, further improving the flame retardant efficiency of the flame retardant particles. In addition, the boron atoms in the modified synergist increase the firmness and density of the carbon layer, effectively inhibit the generation of molten droplets, and give the plastic woven mesh good flame retardant and anti-molten droplet properties;

[0027] The present invention uses octadecyl methacrylate to perform hydrophobic treatment on the surface of the modified intumescent flame retardant system, which effectively avoids its hygroscopic performance and improves the flame retardant efficiency of plastic particles. In addition, the introduction of the modified synergist not only improves the catalytic carbonization efficiency during combustion, but also the honeycomb pores on the surface can absorb small molecular gases released during combustion, thereby reducing the release of toxic gases. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a modified intumescent flame retardant system, which is prepared by the following steps:

[0031] A1. Add 18.4 g of cyanuric chloride to 250 mL of 90 wt% acetone solution, stir and mix, add 9.7 mL of diethanolamine dropwise at 0 ° C, mix evenly, add 17.3 mL of 19.4 wt% sodium hydroxide solution, stir and react for 3 h, then heat to 45 ° C, add 40 mL of 0.21 g / mL piperazine acetone solution dropwise, mix evenly, add the remaining sodium hydroxide solution, react at 80 ° C for 6 h, filter, wash and dry to obtain a modified triazine derivative;

[0032] A2. Add 7.5 g of modified triazine derivative to 8 mL of deionized water, heat to 130°C while stirring, and after it reaches a molten state, add 38.4 g of ammonium polyphosphate, continue stirring and reacting for 3 hours, cool, and grind to obtain a modified intumescent flame retardant system.

[0033] Example 2

[0034] This embodiment provides a modified intumescent flame retardant system, which is prepared by the following steps:

[0035] A1. Add 18.8 g of cyanuric chloride to 250 mL of 90 wt% acetone solution, stir and mix, add 10.0 mL of diethanolamine dropwise at 3 ° C, mix evenly, add 17.3 mL of 19.7 wt% sodium hydroxide solution, stir and react for 3.5 h, then heat to 48 ° C, add 40 mL of 0.22 g / mL piperazine acetone solution dropwise, mix evenly, add the remaining sodium hydroxide solution, react at 80 ° C for 6 h, filter, wash and dry to obtain a modified triazine derivative;

[0036] A2. Add 8.4 g of modified triazine derivative to 8 mL of deionized water, heat to 130°C while stirring, and after it reaches a molten state, add 40.2 g of ammonium polyphosphate, continue stirring and reacting for 3.5 hours, cool, and grind to obtain a modified intumescent flame retardant system.

[0037] Example 3

[0038] This embodiment provides a modified intumescent flame retardant system, which is prepared by the following steps:

[0039] A1. Add 19.2 g of cyanuric chloride to 250 mL of 90 wt% acetone solution, stir and mix, add 10.4 mL of diethanolamine dropwise at 5 ° C, mix evenly, add 17.3 mL of 20.2 wt% sodium hydroxide solution, stir and react for 4 h, then heat to 50 ° C, add 40 mL of 0.23 g / mL piperazine acetone solution dropwise, mix evenly, add the remaining sodium hydroxide solution, react at 80 ° C for 6 h, filter, wash and dry to obtain a modified triazine derivative;

[0040] A2. Add 9.6 g of modified triazine derivative to 8 mL of deionized water, heat to 130°C while stirring, and after reaching a molten state, add 42.5 g of ammonium polyphosphate, continue stirring and reacting for 4 hours, cool, and grind to obtain a modified intumescent flame retardant system.

[0041] Example 4

[0042] This embodiment provides a modified synergist, which is prepared by the following steps:

[0043] B1. Grind the 4A molecular sieve into powder and then pass it through a 200-mesh standard sieve to obtain a pretreated molecular sieve;

[0044] B2. Add 10 g of pretreated molecular sieve to 200 mL of deionized water, stir and disperse, add 2 mL of 0.25 g / mL lanthanum chloride aqueous solution at 85 ° C, mix well, adjust the pH value to 4.5 with 3.75 wt% hydrochloric acid, stir and react at 85 ° C for 1 h, filter, wash and dry, place in 100 mL of diethylene glycol dimethyl ether, mix well, add 0.56 g of boric acid, continue to react at 120 ° C for 5 h, and finally filter, wash and dry to obtain a modified synergist.

[0045] Example 5

[0046] This embodiment provides a modified synergist, which is prepared by the following steps:

[0047] B1. Grind the 4A molecular sieve into powder and then pass it through a 200-mesh standard sieve to obtain a pretreated molecular sieve;

[0048] B2. Add 10.5 g of pretreated molecular sieve to 200 mL of deionized water, stir and disperse, add 2.3 mL of 0.25 g / mL lanthanum chloride aqueous solution at 88 ° C, mix well, adjust the pH value to 4.7 with 3.75 wt% hydrochloric acid, stir and react at 88 ° C for 1.5 h, filter, wash and dry, place in 100 mL of diethylene glycol dimethyl ether, mix well, add 0.56 g of boric acid, continue to react at 125 ° C for 5 h, and finally filter, wash and dry to obtain a modified synergist.

[0049] Example 6

[0050] This embodiment provides a modified synergist, which is prepared by the following steps:

[0051] B1. Grind the 4A molecular sieve into powder and then pass it through a 200-mesh standard sieve to obtain a pretreated molecular sieve;

[0052] B2. Add 11 g of pretreated molecular sieve to 200 mL of deionized water, stir and disperse, add 2.5 mL of 0.25 g / mL lanthanum chloride aqueous solution at 90 ° C, mix well, adjust the pH value to 5.0 with 3.75 wt% hydrochloric acid, stir and react at 90 ° C for 2 h, filter, wash and dry, place in 100 mL of diethylene glycol dimethyl ether, mix well, add 0.56 g of boric acid, continue to react at 130 ° C for 5 h, and finally filter, wash and dry to obtain a modified synergist.

[0053] Example 7

[0054] This embodiment provides a method for preparing flame retardant particles for plastic woven mesh, comprising the following steps:

[0055] Step S1: hydrophobic treatment of modified intumescent flame retardant system:

[0056] Add 5.2 g of octadecyl methacrylate to 200 mL of anhydrous ethanol, stir to dissolve, add 52 g of the modified intumescent flame retardant system, mix evenly, stir and react at 65° C. for 2 h, cool, filter, wash and dry to obtain a hydrophobically modified intumescent flame retardant system;

[0057] Step S2: Preparation of flame retardant particles:

[0058] 48 g of the modified intumescent flame retardant system, 0.2 mL of γ-aminopropyltriethoxysilane, and 2.89 g of the modified synergist were added into a mixer and uniformly mixed, then placed into a screw extruder for melt extrusion, and then cooled, dried, and pelletized to obtain flame retardant particles for plastic woven mesh.

[0059] Example 8

[0060] This embodiment provides a method for preparing flame retardant particles for plastic woven mesh, comprising the following steps:

[0061] Step S1: hydrophobic treatment of modified intumescent flame retardant system:

[0062] Add 6.4 g of octadecyl methacrylate to 200 mL of anhydrous ethanol, stir to dissolve, add 53.5 g of the modified intumescent flame retardant system, mix evenly, stir and react at 68° C. for 3 h, cool, filter, wash and dry to obtain a hydrophobically modified intumescent flame retardant system;

[0063] Step S2: Preparation of flame retardant particles:

[0064] 49 g of a hydrophobically modified intumescent flame retardant system, 0.4 mL of γ-aminopropyltriethoxysilane, and 3.52 g of a modified synergist were added to a mixer and uniformly mixed, then placed in a screw extruder for melt extrusion, and then cooled, dried, and pelletized to obtain flame retardant particles for plastic woven mesh.

[0065] Example 9

[0066] This embodiment provides a method for preparing flame retardant particles for plastic woven mesh, comprising the following steps:

[0067] Step S1: hydrophobic treatment of modified intumescent flame retardant system:

[0068] Add 7.8 g of octadecyl methacrylate to 200 mL of anhydrous ethanol, stir to dissolve, add 55 g of the modified intumescent flame retardant system, mix evenly, stir and react at 70° C. for 4 h, cool, filter, wash and dry to obtain a hydrophobically modified intumescent flame retardant system;

[0069] Step S2: Preparation of flame retardant particles:

[0070] 50 g of the hydrophobically modified intumescent flame retardant system, 0.6 mL of γ-aminopropyltriethoxysilane, and 4.13 g of a modified synergist were added into a mixer and uniformly mixed, then placed into a screw extruder for melt extrusion, and then cooled, dried, and pelletized to obtain flame retardant particles for plastic woven mesh.

[0071] Comparative Example 1: Compared with Example 7, the modified intumescent flame retardant system was replaced with ammonium polyphosphate in equal amount, and the rest was the same.

[0072] Comparative Example 2: Compared with Example 7, the modified synergist was replaced with 4A molecular sieve in equal amount, and the rest was the same.

[0073] Comparative Example 3: Compared with Example 7, no modified synergist was added, and the rest was the same.

[0074] Performance tests were performed on Examples 7 to 9 and Comparative Examples 1 to 3. Polypropylene and flame retardant particles were uniformly mixed in a mass ratio of 8:2, and then melt-spun. After warp and weft interlacing and hot pressing, a polypropylene plastic woven mesh was obtained. Flame retardant performance test: refer to GB / T 2406-93, test the limiting oxygen index value of the sample strip, the higher the limiting oxygen index value, the better the flame retardant performance; mechanical performance test: test the tensile strength before and after combustion, the tensile strength refers to GB / T 1040-1992; vertical combustion test: refer to GB / T 2408-2008, the results are shown in Table 1:

[0075] Table 1

[0076]

[0077]

[0078] As can be seen from Table 1, the plastic particles prepared by the hydrophobically modified intumescent flame retardant system and the modified synergist in Examples 7-9 are used to prepare the polypropylene plastic woven mesh, and the limiting oxygen index value is significantly higher than that of Comparative Examples 1-3, and have good flame retardant properties, and the tensile strength can reach up to 31.6 MPa, and have good mechanical properties; in addition, compared with Comparative Examples 1 and 3, the combustion level of Example 7 can reach V-0 level, and there is no droplet phenomenon, indicating that the plastic particles prepared by the hydrophobically modified intumescent flame retardant system and the modified synergist have better flame retardant efficiency.

[0079] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0080] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing flame retardant particles for plastic woven mesh, characterized in that: The following steps are involved: Step S1: hydrophobic treatment of modified intumescent flame retardant system: Add octadecyl methacrylate to anhydrous ethanol, stir to dissolve, add the modified intumescent flame retardant system, mix evenly, stir to react at 65-70° C. for 2-4 hours, cool, filter, wash and dry to obtain a hydrophobic modified intumescent flame retardant system; Step S2: Preparation of flame retardant particles: The hydrophobically modified intumescent flame retardant system, γ-aminopropyl triethoxysilane and the modified synergist are added into a mixer and uniformly mixed, and then placed into a screw extruder for melt extrusion, and then cooled, dried and pelletized to obtain flame retardant particles for plastic woven mesh cloth; The modified intumescent flame retardant system is prepared by the following steps: A1. Add cyanuric chloride to an acetone solution with a concentration of 90wt%, stir and mix, add diethanolamine dropwise at 0-5°C, mix evenly, add 34.6% of the total amount of sodium hydroxide solution, stir and react for 3-4h, then heat to 45-50°C, add piperazine acetone solution dropwise, mix evenly, add the remaining sodium hydroxide solution, react at 80°C for 6h, filter, wash and dry to obtain a modified triazine derivative; the dosage ratio of the acetone solution, cyanuric chloride, diethanolamine, sodium hydroxide solution and piperazine acetone solution is 250mL:18.4-19.2g:9.7-10.4mL:50mL:40mL; the concentration of the sodium hydroxide solution is 19.4-20.2wt%; the concentration of the piperazine acetone solution is 0.21-0.23g / mL; A2. Add the modified triazine derivative to deionized water, heat to 130°C while stirring, add ammonium polyphosphate after it reaches a molten state, continue stirring and reacting for 3-4 hours, cool, and grind to obtain a modified intumescent flame retardant system; the amount ratio of the deionized water, the modified triazine derivative, and the ammonium polyphosphate is 8mL: 7.5-9.6g:38.4-42.5g; The modified synergist is prepared by the following steps: The pretreated molecular sieve is added to deionized water, stirred and dispersed, and a lanthanum chloride aqueous solution is added at 85-90° C. After mixing evenly, the pH value is adjusted to 4.5-5.0 with hydrochloric acid, and then stirred and reacted at 85-90° C. for 1-2 hours. After filtering, washing and drying, the mixture is placed in diethylene glycol dimethyl ether, mixed evenly, and boric acid is added. The reaction is continued at 120-130° C. for 5 hours. Finally, the modified synergist is obtained after suction filtration, washing and drying. The dosage ratio of the deionized water, the pretreated molecular sieve, the lanthanum chloride aqueous solution, the diethylene glycol dimethyl ether and the boric acid is 200 mL: 10-11 g: 2-2.5 mL: 100 mL: 0.56 g. The concentration of the lanthanum chloride aqueous solution is 0.25 g / mL.

2. The method for preparing flame retardant particles for plastic woven mesh according to claim 1, characterized in that: In step S1, the dosage ratio of anhydrous ethanol, octadecyl methacrylate and modified intumescent flame retardant system is 200 mL: 5.2-7.8 g: 52-55 g; in step S2, the dosage ratio of hydrophobically modified intumescent flame retardant system, γ-aminopropyltriethoxysilane and modified synergist is 48-50 g: 0.2-0.6 mL: 2.89-4.13 g.

3. The method for preparing flame-retardant particles for plastic woven mesh according to claim 1, characterized in that: The pretreated molecular sieve is obtained by grinding 4A molecular sieve into powder and then passing it through a 200-mesh standard sieve.

4. A flame retardant particle for plastic woven mesh, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 3.

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