In-situ preparation method of cyclophosphazene derivative PS-coated organic montmorillonite flame retardant and natural rubber flame retardant application of cyclophosphazene derivative PS-coated organic montmorillonite flame retardant

Abstract

The invention discloses an in-situ preparation method of a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant and natural rubber flame retardant application thereof. The cyclophosphazene derivative PS-coated organic montmorillonite flame retardant comprises organic montmorillonite as a core material and a cyclophosphazene derivative PS as a coating layer, and the surface of the core material is coated with the coating layer; the cyclophosphazene derivative PS is prepared from phosphonitrilic chloride trimer and 4, 4 '-dihydroxy diphenyl sulfone, the cyclophosphazene derivative PS is coated with organic montmorillonite to serve as a flame retardant, the flame-retardant rubber is prepared by blending the flame-retardant rubber with a natural rubber system, the limit oxygen index of the prepared flame-retardant rubber can reach 29.5%, and the peak value of the heat release rate can be reduced to 568.5 KW / m < 2 >.

Description

Technical Field

[0001] The invention relates to a preparation method of a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant and its natural rubber flame retardant application. Background Art

[0002] Natural rubber (NR) is a natural polymer compound whose main chemical structure is composed of polyisobutylene. It has the characteristics of high elasticity, excellent tear resistance and good wear resistance, and is widely used in various fields such as the automotive industry and aerospace components. However, due to its own chemical structure characteristics, products made of natural rubber as raw materials have high fire risks and hidden dangers during the application process, which greatly limits its wider application and development. Therefore, it is necessary to perform certain flame retardant treatment on natural rubber. In recent years, most flame retardant research has been based on the application of halogen flame retardants. These two types of flame retardants will not only produce a large amount of toxic and harmful gases during the combustion of rubber materials, pollute the environment, and endanger human health, but also greatly change the inherent mechanical properties of rubber materials. Compared with the above flame retardants, intumescent flame retardants (IFR) have the advantages of strong anti-dripping, low fire toxicity and low smoke volume.

[0003] Phosphazene flame retardants are rich in nitrogen and phosphorus, and have a nitrogen-phosphorus synergistic flame retardant effect. Their flame retardant mechanism mainly includes condensed phase flame retardancy and gas phase flame retardancy. Among them, hexachlorocyclotriphosphazene (HCCP) is a common compound for preparing phosphazene flame retardants. The phosphorus-chlorine bond in its structure is relatively active, and it is easy to prepare cyclophosphazene derivatives with different functions through substitution reactions. Li et al. synthesized hexa(aniline)cyclotriphosphazene for flame retardant ABS resin (Li R, Sun D, ​​Zhang L. Synthesis of Hexa(Aniline)Cyclotriphosphazene and Its Application in Non-Halogen Fire Retardancy of ABS Resin[J]. New Chemical Materials, 2007, 35(9): 75-76). Yang et al. used poly (4-nitrophenoxy) phosphazene DPP as a carbonizing agent and water resistance agent for ABS to prepare a composite material ABS-DPP (Yang YY, Kong WB, Luo H, et al. Enhancement of Char-Forming and Water Resistance on ABS Modified by Poly (4-Nitrophenoxy)-Phosphazene [J]. Journal of Applied Polymer Science, 2018, 135 (11): 45988). However, there are few reports on the combined effect of phosphazene flame retardants and layered silicates in natural rubber. In addition, both phosphazene flame retardants and layered silicates require a large amount of addition to achieve the expected flame retardant effect, which poses a serious obstacle to their actual industrial application. Therefore, it is very important and urgent to prepare a simple, efficient, halogen-free phosphazene flame retardant by a simple and feasible method. Summary of the invention

[0004] Based on the above situation, the present invention aims to provide a method for preparing a phosphazene derivative PS-coated organic montmorillonite flame retardant and its application in a natural rubber system. The present invention synthesizes a cyclophosphazene derivative PS from hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone, and in situ coats it on the surface of organic montmorillonite to prepare a phosphazene derivative PS-coated montmorillonite flame retardant, which can achieve a synergistic flame retardant effect and is in line with the current concept of green environmental protection.

[0005] An in-situ preparation method of a phosphazene derivative PS-coated montmorillonite flame retardant, characterized in that the method comprises the following steps:

[0006] Step 1. Weigh 200 ml of solvent into a three-necked flask, add 5-20 g of organic montmorillonite, then add 0.1-1 g of polyvinyl pyrrolidone to dissolve, and stir and disperse for 10-40 min;

[0007] Step 2. Hexachlorocyclotriphosphazene, 4,4'-dihydroxydiphenyl sulfone and reagent a are added dropwise to the mixed solution, heated at 40°C, stirred, and reacted for 8-12 hours. The mixed solution after the reaction is centrifuged, washed, and filtered to obtain a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant.

[0008] The cyclophosphazene derivative PS coated organic montmorillonite flame retardant described in the present invention is characterized in that the solvent is selected from at least one of methanol, THF and DMF, and the preferred solvent is THF.

[0009] The cyclophosphazene derivative PS coated organic montmorillonite flame retardant described in the present invention is characterized in that the reagent a is selected from triethylamine, K 2 CO 3 , NaOH, at least one of pyridine, preferably triethylamine.

[0010] The cyclophosphazene derivative PS coated organic montmorillonite flame retardant described in the present invention is characterized in that the mass ratio of the hexachlorocyclotriphosphazene to 4,4'-dihydroxydiphenyl sulfone is 1:(1-3), and the preferred mass ratio is 1:2.

[0011] The cyclophosphazene derivative PS coated organic montmorillonite flame retardant described in the present invention is characterized in that the mass ratio of the hexachlorocyclotriphosphazene, polyvinyl pyrrolidone and reagent a is 1:(0.1-0.15):(5-10), and the preferred mass ratio is 1:0.12:6.

[0012] The present invention has the following advantages and effects:

[0013] 1. The cyclophosphazene derivative PS coated organic montmorillonite flame retardant prepared in the present invention can play a flame retardant role in both the condensed phase and the gas phase. The organic montmorillonite has a good smoke suppression effect, but has poor compatibility with the matrix. The cyclophosphazene derivative has good flame retardancy. Therefore, the cyclophosphazene derivative coating can avoid direct contact between the organic montmorillonite and the matrix, thereby improving the compatibility and dispersibility of the flame retardant and the matrix; the organic montmorillonite can prevent the cyclophosphazene derivative from causing the matrix to decompose early, thereby improving the thermal stability of the system.

[0014] 2. The cyclophosphazene derivative PS coated organic montmorillonite flame retardant prepared in the present invention can obtain a higher limiting oxygen index and a lower heat release rate peak value in the natural rubber system, and has a good flame retardant effect. The flame retardant has high flame retardant efficiency, and a good flame retardant effect can be obtained when the addition amount is 5-20 parts, and no toxic gases such as hydrogen halide are generated during combustion, which conforms to the current new concept of green environmental protection. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and effect of the present invention clearer, the present invention is further described in detail with examples. However, the examples in this specification are only for explaining the present invention but not for limiting the present invention.

[0016] In the following embodiments, the method for preparing the flame retardant rubber comprises the following steps:

[0017] Step 1. Heat the internal mixer to 65°C, add natural rubber and masticate for 3 minutes, then add zinc oxide, stearic acid, carbon black N330, antioxidant 4020, antioxidant TMQ, microcrystalline wax and flame retardant, mix for 14 minutes to prepare a mixed rubber, and extrude it into sheets on an open mixer for standby use;

[0018] Step 2. Add the mixed rubber into the open mixing mill, and add sulfur, accelerator CZ, and accelerator DM according to the feed ratio. Pass the mixture 6 times to mix evenly, and cut into rectangular pieces with a thickness of 2 mm for later use.

[0019] Step 3. Place the mixed rubber in step 2 into a 150°C flat plate vulcanizer and vulcanize for 7-9 minutes to obtain flame retardant rubber for testing.

[0020] The flame retardant rubber of the present invention is characterized in that, based on 100 parts of the mixed rubber, the flame retardant comprises 5-20 parts, sulfur comprises 1-3 parts, accelerator CZ comprises 1-2 parts, accelerator DM comprises 0.5-1 parts, preferably 2 parts of sulfur, 1 part of accelerator CZ, and 0.5 parts of accelerator DM.

[0021] The flame retardant rubber described in the present invention is characterized in that the mixed gel comprises the following components: 100-120 parts of natural rubber, 3-5 parts of zinc oxide, 1-3 parts of stearic acid, 20-40 parts of carbon black N330, 1-3 parts of anti-aging agent 4020, 1-3 parts of TMQ and 1-3 parts of microcrystalline wax, preferably 100 parts of natural rubber, 5-20 parts of flame retardant, 5 parts of zinc oxide, 2 parts of stearic acid, 40 parts of carbon black N330, 2 parts of anti-aging agent 4020, 2 parts of TMQ and 2 parts of microcrystalline wax.

[0022] Example 1

[0023] Add 200ml THF to a 1000mL three-necked flask equipped with a mechanical stirring paddle, a reflux condenser and a thermometer, weigh 5g of organic montmorillonite and add it to the flask, then add 1.2g of polyvinyl pyrrolidone to dissolve, and stir and disperse for 30min. Dissolve 10g of hexachlorocyclotriphosphazene in 100ml THF, add it to a constant pressure funnel, slowly drip it into the flask, mix it thoroughly for 30min, then slowly drip 60ml of pyridine into the flask, and finally slowly drip 20g of 4,4'-dihydroxydiphenyl sulfone dissolved in 50ml THF into the flask, keep the temperature at 40℃, stir, and react for 12h. After the reaction is completed, the mixed solution is centrifuged, washed three times with deionized water, and filtered, and the product is dried in an oven at 60℃ for 24h to obtain a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant.

[0024] 5 g of the obtained cyclophosphazene derivative PS-coated organic montmorillonite flame retardant was added to the prepared flame retardant rubber.

[0025] The flame retardant rubber has a limiting oxygen index of 27.1% and a peak heat release rate of 801.9 KW / m 2 .

[0026] Example 2

[0027] Add 200ml DMF to a 500mL three-necked flask equipped with a stirring paddle, weigh 15g of organic montmorillonite and add it to the flask, then add 0.6g of polyvinyl pyrrolidone and reflux for 30min. Add 5g of hexachlorocyclotriphosphazene dissolved in 50ml of DMF to a constant pressure funnel, slowly drip into the flask, mix thoroughly for 30min, then add 30ml of triethylamine and 10g of 4,4'-dihydroxydiphenyl sulfone dissolved in 50ml of DMF to a constant pressure funnel and slowly drip into the flask, stir at 40℃ for 12h. After the reaction is completed, the mixed solution is centrifuged, washed and filtered, and the product is dried in an oven at 60℃ for 24h to obtain a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant.

[0028] 15 g of the obtained cyclophosphazene derivative PS-coated organic montmorillonite flame retardant was added into the prepared flame-retardant rubber.

[0029] The flame retardant rubber has a limiting oxygen index of 29.5% and a peak heat release rate of 568.5 KW / m 2 .

[0030] Example 3

[0031] Add 200ml of methanol to a 500mL three-necked flask equipped with a reflux condenser, weigh 10g of organic montmorillonite and add it to the flask, then add 0.96g of polyvinyl pyrrolidone to dissolve, and stir and disperse for 30min. Then dissolve 8g of hexachlorocyclotriphosphazene in 50ml of methanol, slowly drip it into the flask from a constant pressure funnel and mix it thoroughly for 30min, then slowly drip 45ml of NaOH into the flask from a constant pressure funnel, and finally dissolve 15g of 4,4'-dihydroxydiphenyl sulfone in 50ml of methanol, slowly drip it into the flask, and stir and react at a constant temperature of 40℃ for 12h. After the reaction is completed, the mixed solution is centrifuged, washed three times with deionized water, and filtered, and the product is dried in an oven at 60℃ for 24h to obtain a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant.

[0032] The obtained 20 g cyclophosphazene derivative PS coated organic montmorillonite flame retardant was added into the prepared flame retardant rubber.

[0033] The flame retardant rubber has a limiting oxygen index of 29.0% and a peak heat release rate of 694.6 KW / m 2 .

Claims

1. A method for preparing a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant, characterized in that: The following steps are involved: Step 1. Weigh 200 ml of solvent into a three-necked flask, add 5-20 g of organic montmorillonite, then add 0.1-1 g of polyvinyl pyrrolidone to dissolve, and stir and disperse for 10-40 min; Step 2. Hexachlorocyclotriphosphazene, 4,4'-dihydroxydiphenyl sulfone and reagent a are added dropwise to the mixed solution, heated at 40°C, stirred, and reacted for 8-12 hours. The mixed solution after the reaction is centrifuged, washed, and filtered to obtain a cyclophosphazene derivative PS-coated organic montmorillonite flame retardant.

2. The cyclophosphazene derivative PS coated organic montmorillonite flame retardant according to claim 1, characterized in that: The solvent of step 1 is selected from at least one of methanol, THF, and DMF, and the preferred solvent is THF; the reagent a of step 2 is selected from at least one of triethylamine, K2CO3, NaOH, and pyridine, and the preferred solvent is triethylamine.

3. The cyclophosphazene derivative PS coated organic montmorillonite flame retardant according to claim 1, characterized in that: The mass ratio of hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone is 1:(1-3), preferably 1:2; the mass ratio of hexachlorocyclotriphosphazene, polyvinyl pyrrolidone and reagent a is 1:(0.1-0.15):(5-10), preferably 1:0.12:

6.

4. The cyclophosphazene derivative PS coated organic montmorillonite flame retardant according to claim 1, characterized in that: The stirring and dispersing time in step 1 is 10-40 minutes, preferably 30 minutes; the reaction time in step 2 is 8-12 hours, preferably 12 hours.