Mg-Al-based hydrotalcite-type particles, chlorine-containing resin composition and process for producing the particles

Abstract

A chlorine-containing resin composition for covering an electric wire of the present invention, has a heat stability of not less than 240 minutes and a volume resistivity of 5.0∞10 13 to 1.0×10 16 Ω·cm when measured according to JIS K6723, and comprises: 100 parts by weight of a chlorine-containing resin, and 1.5 to 10 parts by weight of Mg—Al-based hydrotalcite-type particles having a composition represented by the formula: [Mg x Ca y ]·Al z ·(OH) 2 ·A n− p ·m H 2 O wherein 0.2≦z/(x+z)≦0.6; 0.01≦y/(x+z)≦0.20; x+y+z=1; p=(2(x+y−1)+3z)/n; A is a n-valent anion; and m is more than 0 and not more than 0.75, having a plate surface diameter of 0.1 to 1.0 μm and a thickness of 0.02 to 0.08 μm, and containing calcium at a molar ratio of Ca to a sum of Mg and Al of 0.01:1 to 0.20:1, and having a heat-resisting time of not less than 4 hours upon a chlorine-containing resin composition containing the Mg—Al-based hydrotalcite-type particles.

1 .- 11 . (canceled) 
     
     
         12 . A process for producing the Mg—Al-based hydrotalcite-type particles having a composition represented by the formula:
   [Mg x Ca y ]·Al z ·(OH) 2 ·A n−   p   ·m H 2 O   wherein 0.2≦z/(x+z)≦0.6; 0.01≦y/(x+z)≦0.20; x+y+z=1:   
       p=(2(x+y−1)+3z)/n, A is a n-valent anion; and m is more than 0 and not more than 0.75, having a plate surface diameter of 0.1 to 1.0 μm and a thickness of 0.02 to 0.08 μm and containing calcium at a molar ratio of Ca to a sum of Mg and Al of 0.01:1 to 0.20:1, and showing a heat-resisting time of not less than 4 hours,
 said process comprising: 
 mixing an anion-containing alkali solution, an aqueous magnesium salt solution and an aqueous aluminum salt solution with each other; 
 adding an aqueous calcium solution to the mixed solution such that the molar ratio of Ca to a sum of Mg and Al is 0.01:1 to 0.20:1; and 
 aging the obtained solution at a temperature of 60 to 105° C. while controlling the pH value of the solution to 10 to 14.