Metal hydroxide solid solution, metal oxide solid solution...

Details Metal hydroxide solid solution, metal oxide solid solution... Metal hydroxide solid solution, metal oxide solid solution...

1998-04-15

2001-07-03

Bos, Steven (Department: 1754)

Chemistry of inorganic compounds

Oxygen or compound thereof

Metal containing

C423S594120, C423S599000

Reexamination Certificate

active

06254847

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a magnesium hydroxide solid solution, a magnesium oxide solid solution and processes for their production.
PRIOR ART
In conventional magnesium hydroxides, fine crystals are formed in aggregates having an average secondary particle diameter of about 10 to 100 micrometers. Magnesium oxide formed by using such aggregates as materials have not been homogeneous in terms of particle diameter. For this reason, when the above magnesium hydroxides and magnesium oxides are used as additives for resins, there are disadvantages in that they exhibit poor dispersibility, do not function sufficiently as additives, and tend to destroy physical properties inherent in resins themselves.
To solve the above-described problems, a method of manufacturing a magnesium hydroxide which has good crystal growth (Japanese Patent Publication No. 48809/88) and a method of manufacturing a magnesium oxide having high dispersibility (Japanese Patent Provisional Publication No. 141418/90) have been proposed. Moreover, a magnesium hydroxide solid solution and a magnesium oxide solid solution showing high performance (Japanese Patent Provisional Publications Nos. 41441/94, 209084/93 and 157032/94) have been proposed, in which effects to some extent have been produced. In addition, as large particles for improving mechanical properties and the like, a magnesium hydroxide solid solution and a magnesium oxide solid solution having high aspect ratios have been proposed (Japanese Patent Provisional Publication No. 259235/96).
However, the above-mentioned conventional magnesium hydroxides, magnesium oxides, magnesium hydroxide solid solutions, magnesium oxide solid solutions, and magnesium hydroxide and magnesium oxide solid solutions having high aspect ratios are crystals having a thin and hexagonal-prism-like form, although their crystal sizes vary from small to large. Therefore, when they are kneaded into synthetic resins as additives, problems may be caused such as productivity deteriorates and high density filling cannot be performed due to increase in viscosity of the resins, as well as deterioration in fluidity and processability and a low speed molding. Besides, depending on the resins used, dispersibility in the resins may deteriorate due to factors concerning the shapes of the above solid solutions so that, occasionally, they do not function sufficiently as additives.
SUMMARY OF THE INVENTION
The present invention was made under such circumstances. The present invention aims to provide a metal hydroxide solid solution and a metal oxide solid solution which are improved in terms of fluidity, processability and the like when kneaded into resins and the like, and processes for their production.
To accomplish the above aim, it is in aspect of the present invention to provide a metal hydroxide solid solution represented by the following formula (1);
Mg
1−x
M
2+
x
(OH)
2
  (1)
wherein M
2+
denotes at least one divalent metal ion selected from Mn
2+
, Fe
2+
, Co
2+
, Ni
2+
, Cu
2+
and Zn
2+
and x denotes a number in the range of 0.01≦x<0.5, with a crystal form which is an octahedron comprising upper and lower parallel basal planes and six peripheral pyramidal planes, the pyramidal planes consisting of upward-inclined planes and downward-inclined planes which are alternatively located, the ratio of the major axis diameter of the basal plane to the thickness between the upper and lower basal planes (major axis diameter/thickness) being 1 to 9.
It is another aspect of the present invention to provide a metal oxide solid solution represented by the following formula (2):
Mg
1−x
M
2+
x
O  (2)
wherein M
2+
denotes at least one divalent metal ion selected from Mn
2+
, Fe
2+
, Co
2+
, Ni
2+
, Cu
2+
and Zn
2+
and x denotes a number in the range of 0.01≦x<0.5,
with a crystal form which is an octahedron comprising upper and lower parallel basal planes and six peripheral pyramidal planes, the pyramidal planes consisting of upward-inclined planes and downward-inclined planes which are alternatively located, the ratio of the major axis diameter of the basal plane to the thickness between the upper and lower basal planes (major axis diameter/thickness) being 1 to 9.
It is still another aspect of the present invention to provide a process for producing metal hydroxide solid solution in which composite metal oxide represented by the following formula (3) is hydrated in an aqueous medium, in which 0.1 to 6 mol %, based on the composite metal oxide, of at least one selected from carboxylic acid, metal salt of carboxylic acid, inorganic acid and metal salt of inorganic acid coexists, with strong stirring.
Mg
1−x
M
2+
x
O   (3)
wherein M
2+
denotes at least one divalent metal ion selected from Mn
2+
, Fe
2+
, Co
2+
, Ni
2+
, Cu
2+
and Zn
2+
and x denotes a number in the range of 0.01≦x<0.5.
It is even still another aspect of the present invention to provide a process for producing metal oxide solid solution in which the metal hydroxide solid solution obtained by the above process is burned at not less than 400° C.
As described heretofore, in the metal hydroxide solid solution according to the present invention, the crystal form is an octahedron comprising upper and lower parallel basal planes and six peripheral pyramidal planes, the pyramidal plane consisting of upward-inclined planes and downward-inclined planes which are alternatively located, and the ratio of the major axis diameter of the basal plane to the thickness between the upper and lower basal planes (major axis diameter/thickness) is 1 to 9. Therefore, in the present invention, the crystal form has a completely different crystal habit from the thin and hexagonal-prism crystal of the conventional metal hydroxide solid solution, and, in addition, crystal growth in the direction of the thickness is high. For this reason, unlike the conventional metal hydroxide solid solutions, when the metal hydroxide solid solution of the present invention is kneaded into a synthetic resin as an additive, fluidity and processability of the resin are improved and the molding speed is improved, by which productivity becomes excellent while the filling property is also improved. As a result, dispersibility in the resin becomes good, and when the metal hydroxide solid solutions of the present invention are used as additives for flame retardants, ultraviolet ray absorbents, reinforcing materials, radiating agents and the like, for resins, they may exhibit those functions sufficiently.
With respect to the metal hydroxide solid solution according to the present invention, in the case that the major axis diameter of the basal plane is 0.1 to 10 &mgr;m in average, when such is kneaded into a synthetic resin as an additive, fluidity and processability are further improved so that productivity in resin molding and the like becomes excellent.
With respect to the metal hydroxide solid solution according to the present invention, in the case where M
2+
in the above formula (1) is Zn
2+
, the degree of whiteness is improved and also ultraviolet ray absorbency becomes excellent by solid-soluting Zn
2+
in Mg(OH)
2
.
In addition, in the metal oxide solid solution according to the present invention, as in the above-described metal hydroxide solid solution, the crystal form is an octahedron comprising upper and lower parallel basal planes and six peripheral pyramidal planes, the pyramidal planes consisting of upward-inclined planes and downward-inclined planes which are alternatively located, and the ratio of the major axis diameter of the basal plane to the thickness between the upper and lower basal planes (major axis diameter/thickness) is 1 to 9. Therefore, in the present invention, the crystal form has a completely different crystal habit from those of the conventional oxide and metal hydroxide, and, in addition, crystal growth in the directio

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