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US 4,540,392 AGranted
Method and apparatus to seal coated paperboard materials
AssigneeInternational Paper Company
InventorsJohn E. Junod, Barry P. Fairand
Life of this patent
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AssigneeInternational Paper Company
InventorsJohn E. Junod, Barry P. Fairand
Estimating the term…
A method and apparatus for forming a seam on a thermoplastic coated container, which container has been formed from a single blank or a continuous by bending the substrate member from which container was formed and overlapping opposite edges thereof to form the seam. According to the practice of this invention, the edges of the substrate member which are to be overlapped and joined to form the seam are each heated, prior to their overlapping, by energy from a laser to thereby render the thermoplastic coatings on the overlapped portions of the substrate member soft and tacky so that they will adhere to each other when pressed together and allowed to cool. The laser energy is applied by directing an unfocused laser beam of 10.6 .mu.m wavelength over a zone about one-half inch in width to each of the two edges, the web or blanks being fed along a conveyor past the stationary laser sources.
A method of making a tubular member from a substrate member of foldable, stiff and resilient material such as paperboard or the like, said substrate member being coated on its surfaces with a heat softenable and rehardenable thermoplastic material, the method including:
A method of preparing opposite edges of a substrate member for overlapping and subsequent sealing, to thereby form a container or tubular member seam, the substrate member having heat softenable and rehardenable thermoplastic surfaces, the steps of positioning the surfaces which are to be overlapped to form a wedge shaped cavity, directing an unfocused laser beam into the cavity at such an angle that multiple reflections between the facing, thermoplastic surfaces occur to thereby heat the thermoplastic surfaces the thermoplastic material and the wavelength of the laser energy being so related that the thermoplastic material is substantially transparent to the laser energy, the heating of the thermoplastic material taking place by virtue of absorption of at least a part of the laser energy by the substrate and subsequent conduction of heat from the surface of the substrate to the thermoplastic coating, thereafter, while the thermoplastic surfaces are still tacky, pushing the surfaces together, and thereafter allowing the thermoplastic surfaces to cool and thereby form a seam.
An apparatus for making a container from a blank of stiff, resilient and foldable material such as paperboard coated on its two surfaces with a thermoplastic material, the apparatus including, means for conveying a substrate member, means for generating a beam of laser energy for incidence on at least one of the two opposite edge surfaces of the substrate member, whereby the laser beam heats the thermoplastic coating on which it is incident by heating the substrate and causes the coating to become tacky, whereby the substrate may be then wrapped around a mandrel and the at least one tack edge surface pressed onto an opposite substrate member edge surface to thereby form a seamed tube for forming a container.
Dependencies are inferred from the claim text.