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US 4,743,123 AGranted
Plastic bag and closed plastic bag with laser-formed venting perforations
AssigneeWavin B.V.
InventorsHeinrich Legters, Bernhard Lodder
Life of this patent
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AssigneeWavin B.V.
InventorsHeinrich Legters, Bernhard Lodder
Estimating the term…
A plastic bag of polyolefin material such as polyethylene, for packaging materials, comprising particles of less than 50 .mu.m, and a closed bag containing such materials and a foil material for such a bag. The foil wall of the bag is provided with venting apertures with smooth edges, obtained by laser radiation, having a maximum size of 50-100 .mu.m; the distance between the venting perforations is such that the tensile strength of the foil is substantially the same as the tensile strength of the similar non-perforated foil. In a low density polyethylene foil of a thickness of 130-190 .mu.m distance between the perforations of 80 .mu.m is more than 20 mm, in a linear low density polyethylene foil of about 50-110 .mu.m the perforation distance is at least 5 mm. The bag may consist of two perforated foil layers, the perforations being staggered with respect to each other.
A plastic bag of a polyolefin material having a bag foil wall for packing loosely poured material comprising venting perforations having a size of 50 .mu.m to 100 .mu.m in the bag foil wall, wherein the perforations have smooth edges, which have been formed by laser radiation, the diameter of the perforations being less than or substantially equal to the wall thickness of the foil, said foil wall thickness being between 50 and 250 .mu.m, the distance between the individual perforations being at least 5 mm and such that the tensile strength of the foil is substantially the same as the tensile strength of such a foil which has not been provided with perforations, and
A closed plastic bag of polyolefin material having a bag foil wall filled with a loosely poured material comprising particles of less than 50 .mu.m and having in its bag foil wall venting perforations having a size of 50 .mu.m to 100 .mu.m, wherein the venting perforations are formed by laser radiation with smooth edges and have a size of 50 .mu.m to 100 .mu.m, the diameter of the perforations being less than or substantially equal to the wall thickness of the foil, said foil wall thickness being between 50 and 250 .mu.m, said perforations being at a distance of at least 5 mm from each other and such that the tensile strength of the foil is substantially equal to the tensile strength of a foil not being provided with perforations, whereby said loosely poured material is unable to pass through said bag perforations.
Dependencies are inferred from the claim text.