Patent ID: 7258929

Claim:
A gas-barrier multi-layer structure comprising at least one gas-barrier layer A and at least one thermoplastic resin layer B, the gas-barrier layer A comprising a crystallizable polyamide resin produced by polycondensing a diamine component containing 70 mol % or more of m-wylylenediamine with a dicarboxylic acid component consisting essentially of 80 to 97 mol % of a C4-C20α, ω-linear aliphatic dicarboxylic acid and 3 to 20 mol % of isophthalic acid, and the crystallizable polyamide resin having a minimum half crystallization time of 40 to 2,000 s in a measuring temperature range from a glass transition point thereof to less than a melting point thereof when measured by isothermal crystallization according to depolarization photometry, wherein the polycondensing is conducted by the following steps (1) and (2): (1) melt-polymerizing the diamine component with the dicarboxylic acid component to produce polyamide; and then, (2) solid-phase polymerizing the polyamide obtained in step (1), wherein the relative viscosity t/t0 of the polyamide resin thus obtained is in the range of 2.3 to 4.2, wherein t denotes the dropping time of a solution, prepared by dissolving 1 g of a polyamide resin into 100 ml of 96% sulphuric acid, in a viscosimeter at 25° C., and t0 denotes the dropping time of the 96% sulphuric acid at the same condition, and wherein said solid-phase polymerizing is performed at a temperature in a range of 150° C. to the melting point of the polyamide.