US 4,314,865 AGranted

Method of making cushioning dunnage

AssigneeRanpak Corp.

InventorGary W. Ottaviano

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Abstract

A method and apparatus for the production of air cell cushioning dunnage material, for protective cushioning purposes in packaging or other purposes, with the air cell product possessing substantial strength, and the ability to retain its original thickness under load. The method and apparatus are such that the apparatus can be halted in its operation without injurious effects to the dunnage product being produced, and can be restarted to again commence production of the cushioning dunnage product. The apparatus and method utilize flexible thermoplastic sheets or film of material, to produce the air cell product, with the plastic sheets being preferably formed of a composite of an intermediate stratum of relatively high density high melting point plastic, and exterior stratums of relatively low density, low melting point thermoplastic bonded to the intermediate stratum. Various other embodiments of flexible air cell sheeting are also disclosed.

Claims23

Dependent claims

In a method of manufacturing air cell cushioning dunnage material from flexible plastic sheet, with each of the sheets comprising a composite of an intermediate stratum of high density thermoplastic material generally impervious to the passage of gas therethrough and exterior stratums bonded to the intermediate stratum with the exterior stratums being formed of low density low melting point thermoplastic, with said intermediate stratum being of a high density, higher melting point material as compared to that of the exterior stratums, comprising the steps of heating a first of the composite sheets to a temperature above the melting point temperature of the exterior stratums but below the melting point temperature of the intermediate stratum, embossing said heated first sheet by feeding it onto a rotating forming drum having a plurality of recesses therein and forming the air cells in the recesses on said forming drum by vacuum, heating a second composite sheet of the plastic above the melting point of the exterior stratums of said second sheet, cooling by means of said drum the embossed sheet while on said rotating drum to a temperaure below said melting point temperature of said exterior stratums and to a temperature approaching the softening temperature of the exterior stratums, and then applying said second sheet to said first cooled sheet after the latter has been cooled to said temperature approaching said softening temperature whereby the residue heat in said second sheet causes a melting of the confronting exterior stratum of the cooled embossed sheet sufficiently to cause a bonding of the said first and second sheets at the areas of engagement while on the drum so as to seal the air cells in said product, and then removing the cushioning product from the forming drum.

In a method of manufacturing air cell cushioning dunnage material from a plurality of flexible thermoplastic sheets, each of said sheets comprising a composite of a stratum of high density, high melting point material generally impervious to the passage of gas therethrough and another stratum bonded to the first mentioned stratum with said other stratum being formed of low density, low melting point thermoplastic, and with said first mentioned stratum being of a higher density, higher melting point material as compared to said other stratum, comprising the steps of heating a first of the sheets to a temperature above the melting point temperature of the other stratum but below the melting point temperature of the first mentioned stratum to provide for hot embossment of the sheet, embossing said heated first sheet by feeding it onto a rotating forming drum having a plurality of recesses therein and forming the air cells in the recesses on said forming drum by vacuum, heating a second sheet of the thermoplastic above the melting point of the other stratum of the second sheet, cooling the embossed sheet while on said rotating drum to a temperature below said melting point temperature of said other stratum by maintaining said drum at a predetermined temperature below the first mentioned temperature, and so as to cool said embossed sheet by means of said drum to a temperature approaching the softening temperature of said other stratum thereof, and then applying said second heated sheet to said first sheet after completion of said embossing and said cooling, whereby the residue heat in said second sheet causes a melting of the confronting surface of said other stratum of the cooled embossed sheet sufficiently to cause a bonding together of said other stratums of the said first and second sheets at the areas of engagement while on the drum so as to seal the air cells in said product, and then removing the cushioning product from the forming drum.

Dependencies are inferred from the claim text.