High purity metaphosphate and method for production thereof

Abstract

A high purity metaphosphate, characterized in that it contains each coloring metal element in an amount of 5 ppm or less. Metaphosphates include an aluminum salt, a barium salt, a calcium salt, a magnesium salt and a strontium salt. Aluminum metaphosphate is suitably produced by a method comprising a first step of reacting an aluminum compound with phosphoric acid with heating to prepare a fluidized reaction mixture comprising aluminum biphosphate, a second step of spreading an aluminum metaphosphate powder in a vessel for firing, adding the fluidized reaction mixture comprising aluminum biphosphate from the first step on the powder and then firing them, and a third step of pulverizing the fired product from the second step.

Description

technical field [0001] The present invention relates to high-purity metaphosphate and its production method. Background technique [0002] Now, as environmental problems in the field of electronic materials are becoming more and more serious, lead-free is currently being pursued. In the glass industry, the lead-free process is also being promoted, and the development of high-refractive lenses and low-melting glass is being developed to replace leaded glass. Non-ferrous metals, especially iron, cannot be mixed into this high refraction lens. Phosphate-based glasses, bismuth-based glasses, borosilicate-based glasses, and the like are attracting attention as materials expected to be used as raw materials for high-refractive lenses. Among them, it is considered that metaphosphate is effective as a phosphate-based glass raw material because the average phosphorus content per unit weight is high. [0003] Typical metaphosphates used as phosphate-based glass raw materials includ...

AI Technical Summary

Problems solved by technology

[0005] However, in the production method described in Japanese Patent Laid-Open No. 57-118007, ammonia gas is generated during sintering, and equipment such as waste gas treatment is required.

In addition, impurity levels cannot be reduced

[0006] According to Japanese Patent Application Laid-Open No. 2003-63811, although high-purity aluminum metaphosphate can be obtained, in the preferred reaction to prevent consolidation, a solid-phase reaction that minimizes moisture is used, so the reaction is difficult to complete. , molar ratio (P 2 o 5 / Al 2 o 3 ) disadvantages that are difficult to control

In addition, there is no specific record about the impurity content

[0007] In the method described in Khicmicheskaya Promyshlennost (Moscow, Russian Federation) 1982, 10, 595-7, due to the use of a spray dryer, pollution from nozzles, etc., cannot be avoided

[0008] Japanese Patent Application Laid-Open No. 8-165213 simply describes the production method of zinc phosphate, but there is no description of the detailed production method and impurities.

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