TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Layer: In infrared absorption peaks originating in coupling of metal oxide, coupling of phosphorus compound and coupling in which metal oxide and phosphorus compound are formed and/or mutually react, infrared absorption peak originating in coupling represented by formula: M-O-P, becomes maximum.M=metal atom of metal oxide;P=phosphorus atom of compound having reactive portion;andO=oxygen atom through which metal atom and phosphorus atom are coupled.The phosphorus compound contains two or more portions capable of reacting with metal oxide. The ratio of light absorbency (A2) in wavenumber (n2) and light absorbency (A1) in wavenumber (n1) is 0.2 or less. The wavenumber (n2) is wavenumber from which infrared absorption based on stretching vibration of hydroxyl group becomes maximum in infrared absorption spectrum of layer (Y) in the range of 2500-4000 cm-1. The half value width of absorption peak of the wavenumber (n1) is 200 cm-1 or less. The layer (Y) comprises particles of metal oxide coupled through phosphorus atom derived from phosphorus compound. The number of moles of metal atom with respect to phosphorus atom in the particles is 0-1. Preferred Component: The metal oxide is hydrolysis-condensed product of compound (L) containing metal atom (M) coupled with hydrolysable group. The compound (L) contains at least 1 type of metal-containing compound of formula: M1X1mR1(n-m) (I).M1=Al, Ti or Zr;X1=F, Cl, Br, I, R2O-, R3C(=O)O-, (R4C(=O))2CH- or NO3;R1-R4=alkyl, aralkyl, aryl or alkenyl;n=valence of M1;andm=1-n.The phosphorus compound is chosen from phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, and their derivative. The ratio of number of moles of metal atom contained in metal oxide in the layer (Y), and number of moles of phosphorus atom contained in phosphorus compound is 0.8-4.5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Layer: The layer (Y) further contains polymer (C) containing functional group chosen from hydroxyl group, carboxyl group, carboxylic anhydride group, and salt of carboxyl group. The polymer (C) is chosen from polyvinyl alcohol, ethylene vinyl alcohol copolymer, polysaccharide, polyacrylic acid, its salt, and polymethacrylic acid or its salt. The coating liquid further contains polymer (C) and an acid compound. The acid compound is chosen from acetic acid, hydrochloric acid, nitric acid, trifluoroacetic acid and trichloroacetic acid. Preferred Material: The base material is stratified base material. The base material contains a thermoplastic resin film layer, a paper layer and/or an inorganic vapor deposition layer. The composite structure has water vapor transmission rate of 5 g/(m2.day) or less at 40 degrees C and relative humidity of 90%, and oxygen permeability of 1 ml/(m2.day.atm) or less at 20 degrees C and relative humidity of 85%. The water vapor transmission rate of composite structure after immersing in 120 degrees C hot water at 40 degrees C and relative humidity of 90% for 30 minutes, is 2 times or less than that of structure before immersing. The oxygen permeability of composite structure after immersing in 120 degrees C hot water at 40 degrees C and relative humidity of 85% for 30 minutes, is 2 times or less than that of structure before immersing. Preferred Method: The precursor layer is heat-processed at 110 degrees C or more for 0.1 second to 1 hour. A liquid containing metal oxide and a solution containing phosphorus compound are mixed to obtain coating liquid. The liquid containing metal oxide is obtained by condensing or hydrolytically condensing compound (L), its partial hydrolyzate or fully hydrolyzate product.