Preparation method of high flame retardant expansible graphite

Abstract

The invention relates to a preparation method of high flame retardant expansible graphite, which comprises the following steps: dissolving the graphite into a mixing solution of perchloric acid and concentrated nitric acid, wherein the dosage of the solution is 100-600% of the mass of the solution; oxidizing the graphite by using solid oxidant of which the dosage is 0.5-50% of the mass of the oxidant to obtain the primary expansible graphite, wherein the temperature of the expansible graphite is 20-80 DEG C, and the reaction time is 20-300min; dissolving tripolycyanamide or the derivants thereof and the solid oxidant into phosphoric acid of which the mass fraction is 85+/-10% to form a phosphoric acid solution, wherein the dosage of the solid oxidant is 0.5-50% of the mass thereof, and the mass concentration of the tripolycyanamide or the derivants thereof of the formed phosphoric acid solution is 0.02-2g/ml; carrying out reaction of the primary expansible graphite and the phosphoric acid solution at the temperature of 20-80 DEG C for 20-300min to prepare the high flame retardant expansible graphite. The method has the advantages that the tripolycyanamide or the derivants thereof are inserted between the expansible graphite layers, thereby improving the expansibility, start expansion temperature and fire resistance of the expansible graphite, and can be widely used for the flame retardant of multiple materials such as plastic, rubber, paint, foam and the like.

Description

technical field [0001] The invention relates to a preparation method of a graphite material, in particular to a preparation method of a novel high flame-retardant expandable graphite. Background technique [0002] Expanded graphite, also known as graphite intercalation intercalation compound, is a new type of compound formed by intercalating heterogeneous atoms, molecules or ions between graphite layers by physical or chemical methods. Expanded graphite usually contains 90-98% carbon and is a black flake. It exhibits hundreds of times of volume expansion when subjected to high temperature, and the expanded product has excellent oxidation resistance and high temperature resistance. This feature makes it suitable for use in When a fire occurs, the flame of the flame-retardant polymer material will be smothered by the instantaneous increase in volume to achieve the purpose of flame retardancy and fire prevention. The flame-retardant polymer material has the advantages of non-t...

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Problems solved by technology

[0003]Expandable graphite mainly relies on the expansion insulation layer formed by its own volume expansion to delay or inhibit the combustion of polymers, and there is no or little interaction with the flame-retardant polymers Chemical action occurs, which is a typical condensed phase flame retardant mechanism; due to the weak adhesion between the expanded graphite, after the polymer matrix is ​​burned, the expanded graphite cannot form a solid expanded carbon layer. The expanded carbon layer on the surface may be destroyed under the action of the flame, forming fly ash, which leads to the loss of the thermal insulation expansion layer, and then causes the unburned polymer to be ignited, the flame continues to spread, and the flame retardant efficiency is limited. Combustible polymers often show a strong wick effect, which also weakens their flame retardancy to a certain extent.

Moreover, since the intercalation generally contains sulfur, it is easy to release harmful gases such as sulfur dioxide during the combustion process and pollute the environment, and it expands at a relatively low temperature. In many cases, it is difficult to match the processing temperature of the polymer material. Therefore, it can be The practical application of expanded graphite in the field of polymer flame retardancy is relatively limited

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