Zinc-modified composite polybasic salt, method of preparing the same and use thereof

Abstract

A composite metal polybasic salt containing a trivalent metal, zinc metal and a divalent metal as metal components and having a novel crystal structure, and a method of preparing the same. The invention further deals with a composite metal polybasic salt which has anion-exchanging property, which by itself is useful as an anion-exchanger, capable of introducing anions suited for the use upon anion-exchange, and finds a wide range of applications, and a method of preparing the same. The composite metal polybasic salt has a particular chemical composition and X-ray diffraction peaks, exhibiting peaks at 2θ=2 to 15°, 2θ=19.5 to 24° and 2θ=33 to 50°, and a single peak at 2θ=60 to 64° in the X-ray diffraction (Cu-α).

1 . A composite metal polybasic salt having a chemical composition represented by the following general formula (1), 
       M 2   a Zn b M 3   x (OH) y (A) z .nH 2 O  (1) wherein M 2  is a divalent metal other than Zn, M 3  is a trivalent metal, A is an inorganic or organic anion, and a, b, x, y and z are numbers satisfying the following formulas,    i) 0≦a, 0<b    ii) 3x+2(a+b)−y−mz=0 (wherein m is a valency of anion A),    iii) 0.3≦(a+b)/x≦2.5,    iv) 1.5≦y/(x+a+b)≦3.0, and    v) 4.0≦(x+a+b)/z≦20.0, and    n is a number of not larger than 7,    exhibiting diffraction peaks at 2θ=2 to 15°, 2θ=19.5 to 24° and 2θ=33 to 50°, and a single peak at 2θ=60 to 64° in the X-ray diffraction (Cu-α).    
     
     
         2 . A composite metal polybasic salt according to  claim 1 , wherein an X-ray diffraction (Cu-α) peak at 2θ=33 to 50° is a single peak.  
     
     
         3 . A composite metal polybasic salt according to  claim 1  or  2 , wherein the divalent metal (M 2 ) in said formula is magnesium.  
     
     
         4 . A composite metal polybasic salt according to any one of  claims 1  to  3 , wherein the trivalent metal (M 3 ) in said formula is aluminum.  
     
     
         5 . A composite metal polybasic salt according to any one of  claims 1  to  4 , wherein the anions (A) in said formula are sulfuric acid ions.  
     
     
         6 . A composite metal polybasic salt according to any one of  claims 1  to  4 , wherein the anions (A) in said formula are carbonic acid ions.  
     
     
         7 . A composite metal polybasic salt according to any one of  claims 1  to  4 , wherein the anions (A) in said formula are silicic acid ions.  
     
     
         8 . A composite metal polybasic salt according to any one of  claims 1  to  4 , wherein the anions (A) in said formula are organocarboxylic acid ions.  
     
     
         9 . A composite metal polybasic salt according to any one of  claims 1  to  4 , wherein the anions (A) in said formula are phosphoric acid ions.  
     
     
         10 . A composite metal polybasic salt according to any one of  claims 1  to  9 , wherein said composite metal polybasic salt has a laminate asymmetric index (Is) defined by the following formula (2), 
       Is=tan θ 2 /tan θ 1   (2) wherein θ 1  is an angle subtended by a peak perpendicular in the X-ray diffraction peak of a predetermined spacing and a peak tangent on the narrow angle side, and θ 2  is an angle subtended by the peak perpendicular at the above peak and a peak tangent on the wide angle side,    which is not smaller than 1.5 at a peak of 2θ=33 to 50°.    
     
     
         11 . A method of preparing a composite metal polybasic salt by reacting a water-soluble salt of a trivalent metal with an oxide, a hydroxide or a water-soluble salt of a divalent metal including zinc as an essential component under the conditions of a pH of from 3.8 to 9.0 and a temperature of not lower than 50° C. and, if necessary, executing the ion exchange in the presence of an acid or a soluble salt of acid.  
     
     
         12 . An additive for resins comprising a composite metal polybasic salt of any one of  claims 1  to  10 .  
     
     
         13 . A heat insulator comprising a composite metal polybasic salt of any one of  claims 1  to  10 .  
     
     
         14 . An anion-exchanger comprising a composite metal polybasic salt of any one of  claims 1  to  10 .  
     
     
         15 . An anion-exchanger according to  claim 14 , wherein the anions of the composite metal polybasic salt are sulfuric acid ions.