US Patent 10442574 Expandable web material for envelope construction

An envelope construct having at least two layers and at least two sheet layers and a tilde matrix core placed there between. The tilde matrix core formed as a slit web material having a straight or curvilinear structure that is substantially longer than it is wide, with specially shaped slits, “tilde-slits”, which permit relatively easy expansion upon deployment. The expandable web material is especially well suited for construction of a light-weight, padded envelope that is durable and can withstand significant pressure during use.