The production process of halogen-free flame retardants involves multiple key steps. The following is the detailed production process:
First, raw material selection and preparation
Selected raw materials: The production of halogen-free flame retardants first requires the selection of high-quality raw materials, such as organophosphates, phosphonates, melamine, guanidine salts and other nitrogen-containing compounds. These raw materials should have good flame retardant performance, thermal stability and environmental protection characteristics. When selecting raw materials, it is necessary to strictly control their purity and quality to ensure the smooth progress of subsequent preparations.
Second, synthesis and reaction
Synthesis of Halogen-free PhosphorUs-Based flame retardants
A stable halogen-free flame retardant system is formed by chemically reacting or physically mixing organic or inorganic phosphate esters, phosphonate esters or other phosphorus-containing compounds with the resin matrix. The specific synthetic methods may include addition reactions, polycondensation reactions, etc. For instance, the addition reaction of 9. 10-dihydro9-oxoxa-10-phosphorus-10-oxide, 3. 4-dihydroxybenzaldehyde, dioxane and water under a nitrogen atmosphere yields the first product.
Synthesis of Halogen-free flame retardants based on nitrogen
Modification or compounding based on nitrogen-containing compounds such as melamine and guanidine salts. For instance, the production of expandable graphite requires natural graphite to be treated with concentrated sulfuric acid, washed with water, filtered, dried, and then subjected to expansion treatment at high temperatures. In addition, phase transfer catalysts may also be adopted to promote reactions between solid and liquid phases, such as grafting reactions, to enhance the binding force between flame retardants and polymers as well as the flame retardant efficiency.
Third, compounding and modification
According to different application scenarios and requirements, multiple halogen-free flame retardants are compounded in a certain proportion to achieve better flame retardant effects and compatibility. During the compounding process, factors such as cost, environmental protection and processing performance also need to be taken into consideration. At the same time, it may also be necessary to modify the flame retardant to further improve its performance.
Fourth, post-processing and molding
Mixing and stirring: Add various raw materials to the mixing and stirring equipment in accordance with the formula proportion for thorough mixing to ensure that each component is evenly dispersed.
Grinding and crushing: The mixed flame retardant is ground and crushed to enhance its dispersibility and processing performance.
Drying treatment: Remove excess moisture from the product to enhance its moisture-proof performance.
Granulation molding: Through extrusion, granulation and other methods, flame retardants are made into granular products that are convenient for transportation and addition.
Fifth, performance testing and quality control
Conduct performance tests on the final products, including flame retardant performance, thermal stability, mechanical properties, environmental protection indicators, etc., to ensure that the products meet relevant standards and requirements.
Strictly control all process parameters to ensure the stability of product quality.
Sixth, packaging and storage
Package the flame retardant products and store them in a dry and well-ventilated environment to maintain their stability.
