Tubular object of a layered plastics material and a method for the manufacture thereof

Claim 1

A layered, rigid, dimensionally stable tubular object for packaging and transporting chemicals, beverages, foodstuffs and the like, comprising a first layer of 50 to 1000 μm thickness, a film-shaped interlayer and a second layer of 75 to 1000 μm thickness, said first and second layers being of axially and radially molecular oriented polyethylene terephthalate, said first layer forming the inner wall of the object and said second layer being shrunk onto and clamping the interlayer onto the first layer, said first layer and second layer being of substantially the same thickness and, further, thermally stabilized up to a degree of crystallization of at least 25%.

Claim 9

A method for the manufacture of a tubular object of layered synthetic material for transporting and packaging substances such as chemicals, beverages, foodstuffs, and the like and having a tubular wall of a particular internal cross-section, comprising making the wall by forming a first layer which is obtained by axially and radially stretching a polyethylene terephthalate tubular section to a wall thickness of 50-1000 μm, forming a second layer by thermally shrinking onto the first layer a second tubular section of some plastics material previously stretched in axial and radial direction, characterized in that the first layer is formed by sliding the first tubular section on a mandrel whose external shape corresponds to that of the internal cross-section of the container to be formed, heating this tubular section to above 80° C., as a result of which this tubular section will shrink up to 30% in radial direction onto the mandrel, and on the first layer there is provided an interlayer over which there is slid the second tubular section which is also of polyethylene terephthalate and the second tubular section is heated to above 80° C., upon which this tubular section will shrink up to 30% in radial direction onto the interlayer and lock up the latter, and the second layer is given a wall thickness of 75 to 1000 μm, and the polyethylene terephthalate of the first and second layers is stabilized by heating to a degree of crystallization of at least 25%.

Claim 10

A method for the manufacture of a tubular object of layered synthetic material for transporting and packaging substances such as chemicals, beverages, foodstuffs, and the like and having a tubular wall of a particular internal cross-section, comprising making the wall by forming a first layer which is obtained by axially and radially stretching a polyethylene terephthalate tubular section to a wall thickness of 50-1000 μm, forming a second layer by thermally shrinking onto the first layer a second tubular section of some plastics material previously stretched in axial and radial direction, characterized in that the first layer is formed by sliding the first tubular section on a mandrel whose external shape corresponds to that of the internal cross-section of the container to be formed, heating this tubular section to above 80° C., as a result of which this tubular section will shrink up to 30% in radial direction onto the mandrel, and on the first layer there is provided an interlayer over which there is slid the second tubular section which is also of polyethylene terephthalate and the second tubular section is heated to above 80° C., upon which this tubular section will shrink up to 30% in radial direction onto the interlayer and lock up the latter, and the second layer is given a wall thickness of 75 to 1000 μm, and the polyethylene terephthalate of the first and second layers is stabilized by heating to a degree of crystallization of at least 25%.

Claim 13

A method according to claims 8, characterized in that the interlayer is in the form of a paper sleeve.

Claim 15

A method according to claims 8, characterized in that the interlayer is in the form of a sleeve of plastics film.