Abstract: A polycarboxylic acid mixture comprising 80% by weight or more of 1,3,6-hexanetricarboxylic acid, wherein the polycarboxylic acid mixture has a psychometric lightness L-value of 98 or more, a psychometric chroma a-value of from ?2.0 to 2.0 and a psychometric chroma b-value of from ?2.0 to 3.0, and has a nitrogen content of 5,000 ppm by weight or less.

Abstract: A polycarboxylic acid mixture comprising 80% by weight or more of 1,3,6-hexanetricarboxylic acid, wherein the polycarboxylic acid mixture has a psychometric lightness L-value of 98 or more, a psychometric chroma a-value of from ?2.0 to 2.0 and a psychometric chroma b-value of from ?2.0 to 3.0, and has a nitrogen content of 5,000 ppm by weight or less.

Abstract: A curable composition comprising an epoxy compound having two or more epoxy group per molecule and a curing agent wherein the curing agent comprises a hexanetricarboxylic acid, a cured product obtained from the composition, a curing method of the composition, a coating using the composition, and a coating film obtained by curing the coating. The curing time of this composition is short.

Abstract: The present invention provides an anisotropically porous membrane which is obtained according to a wet process, which comprises a substantially non-sulfonated aromatic polyether ketone having a crystallinity of 10 percent by weight or higher, and which has open pores having an average pore diameter of 0.02 to 30.00 .mu.m on both surfaces of said membrane at an open pore ratio of 7 to 90 percent. In accordance with the present invention, a porous crystalline aromatic polyether ketone membrane is provided which is excellent in heat resistance, chemical resistance, water resistance, water permeability and a balance of water permeability and fractionating characteristics.

Abstract: The present invention is directed to a process for manufacturing a polyether ether ketone (PEEK) membrane which may be used for ultrafiltration or microfiltration at high temperatures. In this process for manufacturing a non-sulfonated PEEK membrane which comprises dissolving PEEK in a solvent to obtain a membrane forming stock solution, forming the stock solution into a desired shape and bringing the formed stock solution in contact with a coagulating liquid capable of coagulating PEEK, the key features involve using concentrated sulfuric acid as the solvent, dissolving PEEK therein to prepare the stock solution and keeping the stock solution at 15 degrees C or lower until initiation of membrane formation.