There is described a method for forming a tube (3) of a web (4, 4) of packaging material comprising the steps of advancing the web (4) of packaging material along a web advancement path (P), overlapping a first lateral edge (19) of the web (4, 4′) of packaging material with a second lateral edge (20) of the web (4, 4) of packaging material for obtaining a longitudinal seam portion of the tube (3) and fusing at least an internal outer surface (34) of the first lateral edge (19) and an external outer surface (37) of the second lateral edge (20) with one another for longitudinally sealing the seam portion of the tube (3). The step of fusing comprises at least the substeps of directly heating the external outer surface (37) of the second lateral edge (20) and heating by contact the internal outer surface (34) by establishing contact between the internal outer surface (34) and the directly heated external outer surface (37).

There is described a method for forming a tube (3) of a web (4, 4) of packaging material comprising the steps of advancing the web (4) of packaging material along a web advancement path (P), overlapping a first lateral edge (19) of the web (4, 4′) of packaging material with a second lateral edge (20) of the web (4, 4) of packaging material for obtaining a longitudinal seam portion of the tube (3) and fusing at least an internal outer surface (34) of the first lateral edge (19) and an external outer surface (37) of the second lateral edge (20) with one another for longitudinally sealing the seam portion of the tube (3). The step of fusing comprises at least the substeps of directly heating the external outer surface (37) of the second lateral edge (20) and heating by contact the internal outer surface (34) by establishing contact between the internal outer surface (34) and the directly heated external outer surface (37).

A strip-shape softened resin sheet (S) which is continuously extruded from a molten resin extruder is cut to a unit resin sheet and a press molded product is manufactured by press-molding the unit resin sheet in a press-molding machine 20. Prior to press-molding the unit resin sheet (U) by the press-molding machine, the unit resin sheet (U) is heated by a heating machine 16. The heating machine 16 comprises a first heating furnace 84 and a second heating furnace 86. The first heating furnace 84 includes a series of heaters 84-3 and 84-4 whose heat source is infrared ray in a far-infrared region and the second heating furnace 86 includes a series of heaters 86-3 and 86-4 whose heat source is the infrared ray in a middle-infrared region. In the first furnace 84, the unit resin sheet (U) is continuously conveyed with a low velocity and is gradually heated by the far-infrared ray up to temperature which is slightly lower than the temperature which is suitable for press-molding the unit resin sheet (U). In the second furnace 86, the unit resin sheet (U) is stopped and is rapidly heated by the middle-infrared ray. By efficiently heating the unit resin sheet (U), a cycle time can be shortened and the production speed can be improved.

A laminate tube with an invisible longitudinal overlapped side seam formed from overlap welding an edge of one margin of a laminate sheet comprising an outer plastic layer (A), a barrier layer (B), and an inner plastic layer (C) of the same material type as the outer plastic layer (A) to the other edge of the opposite margin of the laminate sheet, such that an inner surface of the laminate tube has a hump in a overlapped region, while an outer surface of the laminate tube is smooth without a hump in the overlapped region; and a process for manufacturing the laminate tube by a laminate tube manufacturing machine. The laminate permits fracture-proof welding of longitudinal margins of said laminate to give a continuous tube which is suitable for manufacturing of high-quality plastic tubes, high-quality plastic bags and the like.

A laminate tube with an invisible longitudinal overlapped side seam formed from overlap welding an edge of one margin of a laminate sheet comprising an outer plastic layer (A), a barrier layer (B), and an inner plastic layer (C) of the same material type as the outer plastic layer (A) to the other edge of the opposite margin of the laminate sheet, such that an inner surface of the laminate tube has a hump in a overlapped region, while an outer surface of the laminate tube is smooth without a hump in the overlapped region; and a process for manufacturing the laminate tube by a laminate tube manufacturing machine. The laminate permits fracture-proof welding of longitudinal margins of said laminate to give a continuous tube which is suitable for manufacturing of high-quality plastic tubes, high-quality plastic bags and the like.

A method for manufacturing a microprojection unit (10) according to the invention involves: a microprojection tool forming step of forming a microprojection tool (1) by bringing a projecting mold part (11) into contact from one surface (2D) side of a base sheet (2A) including a thermoplastic resin, and thus forming a protrusion (3) that protrudes from another surface (2U) side, and withdrawing the projecting mold part (11) from the interior of the protrusion (3); a joining step of joining the one surface (2D) side of the base sheet (2A), in which the microprojection tool (1) has been formed, and a tip end of a base component (4); and a cutting step of cutting the base sheet (2A), to which the base component (4) has been joined, along a contour (4L) of the base component (4) at a position more inward than the base component's contour (4L) in a planar view of the base sheet (2A) as viewed from the microprojection tool (1) side, to manufacture a microprojection unit (10).

A method for manufacturing a microprojection unit (10) according to the invention involves: a microprojection tool forming step of forming a microprojection tool (1) by bringing a projecting mold part (11) into contact from one surface (2D) side of a base sheet (2A) including a thermoplastic resin, and thus forming a protrusion (3) that protrudes from another surface (2U) side, and withdrawing the projecting mold part (11) from the interior of the protrusion (3); a joining step of joining the one surface (2D) side of the base sheet (2A), in which the microprojection tool (1) has been formed, and a tip end of a base component (4); and a cutting step of cutting the base sheet (2A), to which the base component (4) has been joined, along a contour (4L) of the base component (4) at a position more inward than the base component's contour (4L) in a planar view of the base sheet (2A) as viewed from the microprojection tool (1) side, to manufacture a microprojection unit (10).

This invention relates to an anisotropic multilayer film and the process of making a multilayer film, wherein a supercritical blowing agent is introduced to at least one layer, wherein at least one layer comprises 10 to 100 percent by weight LLDPE with a melt index of 0.2 to 2 g/10 min. The film in this invention can have a surface with an average Sheffield smoothness, according to TAPPI T 538, of less than 100. The film in this invention can have a puncture propagation tear resistance, in accordance with ASTM D2582, greater than 500 g/mil.

A process is provided for heat sealing substrate layers. The process comprising: conveying an upper die having a heating conductor and a lower die having a heating conductor to a sealing region, where a substrate is applied to one or more items; activating a power supply system; monitoring, via the power supply system, a temperature of the heating conductor of the upper die when in the sealing region; monitoring, via the power supply system, a temperature of the heating conductor of the lower die when in the sealing region, wherein the monitoring of the temperature of the heating conductor of the upper die is performed independently of the monitoring of the temperature of the heating conductor of the lower die; supplying power to the upper die based on the temperature of the heating conductor of the upper die; supplying power to the lower die based on the temperature of the heating conductor of the lower die, wherein the power is supplied to the lower die independently of the power being supplied to the upper die.

A process is provided for heat sealing substrate layers. The process comprising: conveying an upper die having a heating conductor and a lower die having a heating conductor to a sealing region, where a substrate is applied to one or more items; activating a power supply system; monitoring, via the power supply system, a temperature of the heating conductor of the upper die when in the sealing region; monitoring, via the power supply system, a temperature of the heating conductor of the lower die when in the sealing region, wherein the monitoring of the temperature of the heating conductor of the upper die is performed independently of the monitoring of the temperature of the heating conductor of the lower die; supplying power to the upper die based on the temperature of the heating conductor of the upper die; supplying power to the lower die based on the temperature of the heating conductor of the lower die, wherein the power is supplied to the lower die independently of the power being supplied to the upper die.