Tubular container with invisible longitudinal overlapped side seam

A process for manufacturing a laminate tube with an invisible longitudinal overlapped side seam, wherein there is a hump in an overlapped region on an inner surface of the laminate tube, while there is no said hump on an outer surface of the laminate tube, by a laminate tube manufacturing machine, this process comprising:

• disposing a laminate sheet comprising an outer plastic layer, a barrier layer, and an inner plastic layer of the same material type as the outer plastic layer into a welding zone, wherein edges of both margins of the laminate sheet are cut obliquely at a predetermined angle of more than or equal to 30° and less than 90°, and wherein one obliquely-cut edge of one margin is overlapped correspondingly to the other obliquely-cut edge of the opposite margin of the laminate sheet, before welding;
• welding said obliquely-cut edges of both margin of the laminate sheet in the welding zone by an overlap welding means adjusted in the lengths of contact belts heated by energy sources to be less than or equal to 20 mm in order to overlap-weld the edges of both margin of said laminate sheet by the heat energy sources under pressure;
• and
• cooling the overlapped side seam rapidly in a cooling zone at a temperature of less than or equal to 15° C.

A process for manufacturing a laminate tube with an invisible longitudinal overlapped side seam, wherein there is a hump in an overlapped region on an inner surface of the laminate tube, while there is no said hump on an outer surface of the laminate tube, by a laminate tube manufacturing machine, this process comprising:

• disposing a laminate sheet comprising an outer plastic layer, a barrier layer, and an inner plastic layer of the same material type as the outer plastic layer into a welding zone, wherein edges of both margins of the laminate sheet are cut obliquely at a predetermined angle of 45° to 60°, and wherein one obliquely-cut edge of one margin is overlapped correspondingly to the other obliquely-cut edge of the opposite margin of the laminate sheet, before welding;
• welding said obliquely-cut edges of both margin of the laminate sheet in the welding zone by an overlap welding means adjusted in the lengths of contact belts heated by energy sources to be less than or equal to 10 mm in order to overlap-weld the edges of both margin of said laminate sheet by the heat energy sources under pressure;
• and
• cooling the overlapped side seam rapidly in a cooling zone at a temperature of 10-15° C.