The present invention provides a layered double hydroxide with improved conductivity, a layered double hydroxide and a composite material containing the layered double hydroxide. The layered double hydroxide is represented by the general formula: [Mg.sup.2+.sub.(1-y)M1.sup.+.sub.y].sub.1-x[Al.sup.3+.sub.(1-z)M2.sup.+.sub.z].sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O, wherein 0.1x0.4, 0y0.95, and 0z0.95, provided that both y and z are not 0 at the same time; =1 or 2; =2 or 3; A.sup.n is an n-valent anion, provided that n is an integer of 1 or greater; m0; M1.sup.+ is a cation of at least one substituent element selected from monovalent elements, transition metal elements, and other elements with an ionic radius greater than that of Mg.sup.2+; and M2.sup.+ is a cation of at least one element selected from divalent elements, transition metals, and other elements with an ionic radius greater than that of Al.sup.3+.

The present invention aims to provide techniques for preparing complexes of a hydrotalcite and a fiber. The complexes of a hydrotalcite and a fiber can be synthesized efficiently by synthesizing the hydrotalcite in an aqueous system in the presence of the fiber.

Surface-modified layered double hydroxides (LDHs) are disclosed, as well as processes by which they are made, and uses of the LDHs in composite materials. The surface-modified LDHs of the invention are more organophilic than their unmodified analogues, which allows the LDHs to be incorporated in a wide variety of materials, wherein the interesting functionality of LDHs may be exploited.

The invention relates to a method for exchanging interlayer anions of a layered double hydroxide (LDH) with other anions whose affinity for the LDH is lower than the one of the starting interlayer anions, which comprises the successive steps of: (1) exchanging the starting interlayer anions of a layered double hydroxide with polyoxometalate anions in order to obtain a layered double hydroxide with polyoxometalate anions as interlayer anions, and (2) exchanging the polyoxometalate anions of the layered double hydroxide obtained in step (1) with other anions whose affinity for the LDH is lower than the one of the starting interlayer anions in order to obtain a layered double hydroxide with other anions as interlayer anions.

Provided is a layered double hydroxide membrane containing a layered double hydroxide represented by the formula: M.sup.2+.sub.1-xM.sup.3+.sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O (where M.sup.2+ represents a divalent cation, M.sup.3+ represents a trivalent cation, A.sup.n represents an n-valent anion, n is an integer of 1 or more, and x is 0.1 to 0.4), the layered double hydroxide membrane having water impermeability. The layered double hydroxide membrane includes a dense layer having water impermeability, and a non-flat surface structure that is rich in voids and/or protrusions and disposed on at least one side of the dense layer. The present invention provides an LDH membrane suitable for use as a solid electrolyte separator for a battery, the LDH membrane including a dense layer having water impermeability, and a specific structure disposed on at least one side of the dense layer and suitable for reducing the interfacial resistance between the LDH membrane and an electrolytic solution.

The invention provides hydrotalcite that can inhibit foaming and can exhibit excellent heat stability when added to resins such as chlorine-containing resins, while also inhibiting resin coloration, without the combined use of additives with the resins. The hydrotalcite of the invention is represented by formula (1) and has a specific surface area of 120 m.sup.2/g to 250 m.sup.2/g as determined by the BET method.

M.sup.2+.sub.xZn.sub.y.Math.M.sup.3+.sub.zO.sub.x+y+(3/2)z(1) (In the formula, M.sup.2+ represents at least one divalent metal ion, M.sup.3+ represents at least one trivalent metal ion, and x, y and z represent numbers satisfying 0<x? 0.5, 0<y? 0.2 and 0<z?0.4.)

Layered double hydroxides (LDHs) are disclosed, as well as methods by which they may be manufactured. The LDHs are subjected to a solvent treatment step during manufacture, which confers high surface area and pore volume properties to the LDHs. The particular solvents used in the preparation of the LDHs renders allows for an overall more efficient and environmentally-friendly manufacturing process.

Catalyst supports prepared from Ni.sup.2+-containing layered double hydroxides are disclosed. together with processes by which they are made and catalyst compositions comprising them. When used in the polymerisation of an olefin. the catalyst supports give control over the molecular weight distribution of the resulting polyolefin.

Catalyst supports prepared from Ni.sup.2+-containing layered double hydroxides are disclosed. together with processes by which they are made and catalyst compositions comprising them. When used in the polymerisation of an olefin. the catalyst supports give control over the molecular weight distribution of the resulting polyolefin.

Provided is a layered-double-hydroxide-containing composite material including a porous substrate and a functional layer disposed on and/or in the porous substrate, the functional layer containing a layered double hydroxide represented by the formula M.sup.2+.sub.1-xM.sup.3+.sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O, where M.sup.2+ represents a divalent cation, M.sup.3+ represents a trivalent cation, A.sup.n represents an n-valent anion, n is an integer of 1 or more, and x is 0.1 to 0.4, and the functional layer further containing sulfur (S) at the interface between the functional layer and the porous substrate and in the vicinity of the interface. In the LDH-containing composite material of the present invention, the LDH-containing functional layer disposed on and/or in the porous substrate exhibits significantly improved conductivity.