Polyphosphate surface coating method

Abstract

The invention discloses a polyphosphate coating method which is characterized in that the surfaces of polyphosphate particles are coated with a layer of organic silicon, the polyphosphate is melamine polyphosphate and piperazine pyrophosphate, the organic silicon is amino silicon oil, and the content of the organic silicon is 0.5%-20% of the mass of the polyphosphate particles. The polar group and hydrophobicity of the amino silicon oil are utilized, so that the hydrophilicity of the polyphosphate is obviously reduced, the processing stability of the polyphosphate is improved, and the flame retardant property of the polyphosphate is improved. The method has the advantages of low process requirements, low cost and the like, does not contain metal ions and chemical solvents, is easy to operate and implement, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of polyphosphate surface coating treatment, and in particular to a method for coating a polyphosphate flame retardant with organosilicon. Background Art

[0002] Polyphosphates are a type of highly efficient intumescent flame retardant because they contain both phosphorus and nitrogen. However, it is still a great challenge to improve their thermal stability, water resistance, precipitation, and processability.

[0003] CN 104039927 B discloses a method for preparing a melamine phosphate flame retardant with excellent dispersibility, electrical insulation and water resistance by using metal compounds and cyanuric acid in the reaction of melamine compounds and phosphorus compounds. CN 106831625 A discloses a melamine polyphosphate modified by metal ions and a preparation method thereof, which has good high temperature stability, excellent flame retardant effect, wide application range, simple process steps, mild reaction conditions, stable and controllable reaction process, low energy consumption, small environmental pollution, and basically no corrosion to equipment and pipelines. CN 111574751 A discloses a method for preparing a coated water-resistant melamine polyphosphate flame retardant, directly synthesizing the coated modified melamine polyphosphate, and using silane coupling agent and polyethylene as coating materials for graded coating. CN 113580293 A discloses a highly dispersed modified polyphosphate flame retardant and a preparation method thereof. Melamine, diammonium phosphate and silane coupling agent are used to synthesize silane-modified melamine phosphate (Si-MP) under the action of a catalyst, and then the temperature is raised and thermally polymerized to prepare a silane-modified polyphosphate (Si-MPP) with high dispersibility. CN115010996A discloses a method for preparing a microencapsulated core-shell structure-coated piperazine pyrophosphate composite flame retardant, in which carbon nanotubes are coated on the outer surface of piperazine pyrophosphate through a silane coupling agent. The above invention uses metal ions, silane coupling agents, polyethylene, carbon nanotubes, etc. to modify the surface of melamine polyphosphate and piperazine pyrophosphate. Summary of the invention

[0004] The invention provides a polyphosphate surface coating method, which utilizes the polar groups and hydrophobicity of amino silicone oil to significantly reduce the hydrophilicity of polyphosphate, improve its processing stability, and improve the flame retardant performance of polyphosphate.

[0005] A melamine polyphosphate surface coating method, characterized in that it comprises the following process steps: (1) drying the prepared polyphosphate in a dehumidified oven at 100° C. to 120° C. until the moisture content is less than 0.2%, preferably less than 0.1%; (2) Add the dried polyphosphate to a high-speed mixer, add 0.5% to 20% amino silicone oil based on its mass fraction while stirring at high speed, and stir for 15min-30min to obtain surface-coated melamine polyphosphate. The speed of the high-speed mixer is 10000RPM~30000RPM. The amino value of the amino silicone oil is 0.1%~5%, and the amino group can be various groups such as primary amine, secondary amine, hindered amine, piperazine, etc. The viscosity is 250cps~9000cps, preferably 1000cps~9000cps, and octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the amino silicone oil whose ring body content is less than 1000ppm is further preferred. DETAILED DESCRIPTION

[0006] The present invention will be further described below in conjunction with specific embodiments.

[0007] The melamine polyphosphate used in the present invention is PNA350 produced by Hangzhou Jieersi Flame Retardant Chemical Co., Ltd. Piperazine pyrophosphate is JNP-2 produced by Sichuan Fine Chemical Research and Design Institute. Amino silicone oil and dimethyl silicone oil are both from Jiangxi Lanxing Xinghuo Silicone Co., Ltd. The viscosities of C845 and C803 are 4500 and 300 cps respectively.

[0008] The coated melamine polyphosphate particles of the present invention are coated with a layer of organosilicon on the surface of the melamine polyphosphate particles, wherein the content of the organosilicon is 0.5-10% of the mass of the melamine polyphosphate particles. The improved method of the present invention can be used to treat polyphosphate flame retardant powders produced by any production method.

[0009] Embodiment 1: A melamine polyphosphate surface coating method, comprising the following process steps: (1) drying melamine polyphosphate in a dehumidified oven at 100°C-120°C until the moisture content is less than 0.09%; (2) Add the dried melamine polyphosphate into a high-speed mixer, add 10% by mass of amino silicone oil C845 while stirring at high speed, and stir for 15 minutes to obtain the surface-coated melamine polyphosphate.

[0010] Embodiment 2: A melamine polyphosphate surface coating method, comprising the following process steps: (1) drying melamine polyphosphate in a dehumidified oven at 100°C-120°C until the moisture content is less than 0.09%; (2) Add the dried melamine polyphosphate into a high-speed mixer, add 10% by mass of amino silicone oil C803 while stirring at high speed, and stir for 15 minutes to obtain a surface-coated melamine polyphosphate.

[0011] Embodiment 3: A method for coating the surface of piperazine pyrophosphate, comprising the following process steps: (1) Drying piperazine pyrophosphate in a dehumidified oven at 100°C-120°C to a moisture content of less than 0.09%; (2) Add the dried piperazine pyrophosphate into a high-speed mixer, add 0.5% amino silicone oil FLD24168 based on the mass fraction of the piperazine pyrophosphate while stirring at high speed, and stir for 30 minutes to obtain the surface-coated piperazine pyrophosphate.

[0012] Comparative Example 1: A melamine polyphosphate surface coating method, comprising the following process steps: (1) drying melamine polyphosphate in a dehumidified oven at 100°C-120°C until the moisture content is less than 0.09%; (2) Add the dried melamine polyphosphate into a high-speed mixer, add 10% by mass of dimethyl silicone oil 47V5000 while stirring at high speed, and stir for 15 minutes to obtain the surface-coated melamine polyphosphate.

[0013] Comparative Example 2: A melamine polyphosphate surface coating method, comprising the following process steps: (1) drying melamine polyphosphate in a dehumidified oven at 100°C-120°C until the moisture content is less than 0.09%; (2) Add the dried melamine polyphosphate into a high-speed mixer and stir at high speed for 15 minutes as a comparative melamine polyphosphate.

[0014] Comparative Example 3: A method for coating the surface of piperazine pyrophosphate, comprising the following process steps: (1) drying piperazine pyrophosphate in a dehumidified oven at 100°C-120°C to a moisture content of 0.09%; (2) Add the dried piperazine pyrophosphate into a high-speed mixer and stir at high speed for 15 minutes as a comparison of piperazine pyrophosphate.

[0015] The hydrophobicity test adopts the water infiltration method. 5g of the polyphosphate powder and piperazine pyrophosphate treated in Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 are weighed and added to the water surface in 4 beakers with water, and placed at room temperature. The hydrophobicity is determined by the infiltration time of the powder and water. The results are as follows: Embodiment 1 Embodiment 2 Embodiment 3 Comparative Example 1 Comparative Example 2 Time for all powder to be immersed in water >30 days 25 days 11 days 2 days Quickly soak in water The flame retardant properties and processing stability are taken as examples of nylon 6 glass fiber reinforced materials and PP materials.

[0016] The nylon 6 glass fiber reinforcement material is composed of the following raw materials in weight percentage: PA6 (53%), alkali-free glass fiber (30%), diethyl aluminum hypophosphite OP1230 (16%), and coated melamine polyphosphate (1%). The PA6 brand is Xinhui Meida M2800, and the alkali-free glass fiber is Jushi 988A.

[0017] The preparation method of the above-mentioned polyamide composite material is as follows: nylon 6, the flame retardant OP1230 prepared by the above method and the coated melamine polyphosphate are added to a high-speed mixer at 3000RPM and mixed for 1 minute, and then added to a twin-screw extruder from a main feeding hopper, and glass fiber (i.e., alkali-free glass fiber) is added to the twin-screw extruder from a side material. After extrusion by the twin-screw extruder, the polyamide composite material is water-cooled, pelletized and dried to obtain the polyamide composite material; the temperature settings of the twin-screw extruder from the first temperature section to the eighth temperature section from the feed section to the die head are 230°C, 235°C, 245°C, 235°C, 225°C, 215°C, 215°C, 215°C, respectively, the temperature of the die head is 235°C, and the output is 1kg / min.

[0018] The above various polyamide composite materials were injection molded into 3.2mm / 1.6mm flame retardant specimens by an injection molding machine for flame retardant performance testing, and the melt flow index of the material was tested at the same time.

[0019] Here are the results: formula Recipe 1 Recipe 2 Recipe 3 Recipe 4 PA6 53% 53% 53% 53% Fiberglass 30% 30% 30% 30% OP1230 16% 16% 16% 16% Example 1 Coated melamine polyphosphate 1% / / Example 2 Coated melamine polyphosphate 1% Comparative Example 1: Coated melamine polyphosphate / 1% Comparative Example 2 Treated Melamine Polyphosphate 1% Test items Vertical burning 3.2mm V-0 V-0 V-1 V-1 Vertical burning 1.6mm V-1 V-1 V-1 Not flame retardant MI 275℃ / 2.16kg 23g / 10min 30g / 10min 41g / 10min 43g / 10min In the flame retardant test in the table above, although both formula 1 and formula 2 are V0 grade when burning vertically at 3.2mm, the self-extinguishing time during the test is different, within 1s for formula 1 and 1~2s for formula 2. It can also be seen from MI that the high viscosity amino silicone oil treatment effect is better.

[0020] The PP material is composed of the following raw materials in weight percentage: PP (72%), coated with piperazine pyrophosphate (28%). The PP grade is Shanghai Petrochemical T300.

[0021] The preparation method of the composite material is as follows: PP and coated piperazine pyrophosphate are added into a high-speed stirrer and mixed at 3000RPM for 1 minute, and then added into a twin-screw extruder from a main feeding hopper, and after being extruded by the twin-screw extruder, the composite material is water-cooled, pelletized and dried to obtain a polypropylene composite material; the temperature settings of the twin-screw extruder from the first temperature section to the eighth temperature section from the feed section to the die are 190°C, 200°C, 200°C, 200°C, 190°C, 180°C, 180°C and 170°C respectively, the temperature of the die head is 200°C, and the output is 0.6kg / min.

[0022] The above PP composite material was injection molded into 3.2mm / 1.6mm flame retardant specimens by an injection molding machine for flame retardant performance testing.

[0023] Here are the results: formula Recipe 5 Recipe 6 PP 72% 72% Example 2 Coated piperazine pyrophosphate 28% / Comparative Example 3: Piperazine pyrophosphate treated / 28% Test items Vertical burning 3.2mm V-0 V-0 Vertical burning 1.6mm V-1 Not flame retardant It can be seen from the above data that the coated polyphosphate of the present invention has good hydrophobicity, flame retardancy and processing stability.

Claims

1. A polyphosphate surface coating method, characterized in that: A layer of organic silicon is coated on the surface of the polyphosphate particles.

2. A polyphosphate surface coating method according to claim 1, characterized in that: The polyphosphates are melamine polyphosphate and piperazine pyrophosphate.

3. A polyphosphate surface coating method according to claim 1, characterized in that: The coating agent is amino silicone oil, specifically a polymer silicone oil containing primary amine groups or secondary amine groups on the molecular side chain or terminal group or on the side chain and terminal group; the viscosity of the amino silicone oil is 1000cps~9000cps.

4. A polyphosphate surface coating method according to claim 1, characterized in that: The process steps include: (1) drying the prepared polyphosphate in a dehumidified oven at 100° C. to 120° C. until the moisture content is less than 0.1%; (2) Add the dried polyphosphate to a high-speed mixer, add 0.5% to 20% amino silicone oil based on its mass fraction while stirring at high speed, and stir for 15 minutes to 30 minutes to obtain a surface-coated melamine polyphosphate.