Method for preparing encapsulated red phosphorus

Abstract

The invention discloses a method for preparing encapsulated red phosphorus. The method comprises the following steps of: mixing red phosphorus powder and hypophosphite with two organic groups to prepare water suspension, wherein the molecular formula of the hypophosphite with two organic groups is (R1R2PO2)nM; adjusting the pH value of the solution to be 3 to 5 by using acid solution, raising the temperature to 50 to 60 DEG C, adjusting the pH value until the solution is neutral by using aqueous alkali; and continuously stirring for 0.5 to 2 hours, cooling and suction-filtering, washing with water, and performing vacuum drying to obtain the encapsulated red phosphorus product. In the method for preparing the encapsulated red phosphorus, the hypophosphite with two organic groups is directly added into the suspension of red phosphorus, the hypophosphite with two organic groups is deposited on the surfaces of the red phosphorus particles directly by adjusting the pH value of the solution, good stabilization effect can be used by using a small amount of a stabilizing agent, the phosphorus content of the product can be kept as much as possible, and the double effect of stabilizing and inflaming retarding can be achieved, so that an ideal and stable encapsulated red phosphorus product can be obtained.

Description

technical field [0001] The invention relates to a preparation method of coated red phosphorus. [0002] Background technique [0003] Red phosphorus is transformed from yellow phosphorus (also known as white phosphorus) through a high temperature above 260 degrees. The commonly used industrial product is purple-red fine powder of 10-1000 μm. The insecticide aluminum phosphide and pesticide raw materials, as a highly efficient flame retardant in polymer materials such as plastic rubber, is a strange discovery in the scientific community. However, in humid air, the surface of red phosphorus particles is prone to oxidation and oxidation with oxygen. The disproportionation reaction generates various phosphorus-containing acids and releases toxic phosphine gas. Phosphorus-containing acids have a great negative impact on the further application of red phosphorus and even fail. Toxic phosphine gas will also pollute the workplace and threaten Personnel health. [0004] At present...

AI Technical Summary

Problems solved by technology

[0003] Red phosphorus is transformed from yellow phosphorus (also known as white phosphorus) through a high temperature above 260 degrees. The commonly used industrial product is purple-red fine powder of 10-1000 μm. The insecticide aluminum phosphide and pesticide raw materials, as a highly efficient flame retardant in polymer materials such as plastic rubber, is a strange discovery in the scientific community. However, in humid air, the surface of red phosphorus particles is prone to oxidation and oxidation with oxygen. The disproportionation reaction generates various phosphorus-containing acids and releases toxic phosphine gas. Phosphorus-containing acids have a great negative impact on the further application of red phosphorus and even fail. Toxic phosphine gas will also pollute the workplace and threaten Personnel health

[0004] At present, metal hydroxides are deposited on the surface of red phosphorus for stabilization, such as hydroxides of aluminum, magnesium, zinc, calcium, tin, nickel, silver, and titanium, and there are also methods of depositing metal phosphates, but due to the heat of these compounds Insufficient stability. When used as a flame retardant, bound water and crystal water will be released due to heat during the processing of plastics, resulting in the degradation of polymer materials and reducing the mechanical properties of materials. Silicone oils, phosphate esters, and waxes are also used. The dust removal treatment of red phosphorus with small molecular compounds can also partially prevent oxidation, but the effect is not ideal. There are also thermosetting resins such as epoxy, phenolic formaldehyde, melamine formaldehyde, and polyurethane to coat red phosphorus with microcapsules. , and the stabilization of combined metal hydroxides, but due to problems such as poor compatibility, low molecular weight formaldehyde and difficulty in dispersing, it is necessary to add a considerable amount of hydroxide stabilizers and coating resins to achieve a certain stabilization effect , which reduces the effective content of red phosphorus in the coated product; the published patent USP4136154 uses organic hypophosphite to coat red phosphorus, which is to suspend red phosphorus in an aqueous solution, add organic hypophosphorous acid and water-soluble metal salts, and react to form organic Hypophosphite is deposited on the surface of red phosphorus, but in this method, the addition of organic hypophosphorous acid or water-soluble metal salt is large, there are many by-products, and the ratio is difficult to control, resulting in unsatisfactory stabilization of the coated red phosphorus product