Ink container, valve unit, ink container manufacturing method, ink jet head cartridge and recording apparatus

An ink container detachably mountable to a portion to be mounted, comprising:

• a substantially prism-shaped casing having an opening;
• a multi-layer inner bladder deformable with discharge of liquid, said inner bladder having an outer surface which is equivalent or similar to an inner surface of said casing, said casing and said inner bladder constituting a liquid reservoir;
• a valve unit, provided in a liquid supply opening of said liquid reservoir, for permitting discharge of the liquid contained in the inner bladder;
• and
• a discrimination member for discriminating the liquid in the liquid reservoir, said discrimination member being detachably mountably fixed by connecting means having a disassembling easiness property relative to said liquid reservoir;
• wherein said valve unit and said inner bladder of said liquid reservoir are made of the same thermoplastic resin material and are welded to each other.