Jig-saw puzzles

Abstract

a jig-saw puzzle comprises interfitting pieces (1, 2, 3, 4) which when fitted together side-by-side form a three-dimensional upper surface simulating for example hills and valleys. Each piece is formed of a molded open or closed cell thermoplastics foamed core 7 sandwiched between upper and lower thermoplastics skins 8a and 8b. A printed sheet 9 is stuck on to the upper skin 8a. The skins 8a and 9a may be made from any conventional moldable thermoplastics. A preferred thermoplastics is a copolymer of propylene with from 5 to 20% by weight of ethylene made by injecting ethylene into the final stages of an otherwise propylene homopolymerization. The core may be made of the same or different plastics as the skins. Polyurethane is a preferred core material. The printed sheet, which may be paper or fabric, may be stuck on to the upper sheet with adhesive or by penetration or fusing of the skin material into the sheet during molding of the pieces.

Description