GB1293456A - A process for producing a reticulated sheet and a reticulated sheet produced in accordance with the process - Google Patents

Abstract

1293456 Reticulated films; laminates BREVETEAM SA 12 March 1970 [18 April 1969 29 April 1969 25 Oct 1969] 11865/70 Headings B5B and B5N Reticulated films and sheets are made from sheet webs which are shrinkable in at least one direction, and made from a thermoplastic high polymer organic synthetic material by forming substantially parallel rows of slits in the sheet, slits of adjacent parallel rows being offset and said slits being disposed at right-angles to the direction of shrinking of the sheet, and then subjecting the sheet to heat or solvent to effect a shrinking of the material web between the slits to a thickened form and to thus form netlike openings by opening of the slits. Specified materials include polyamides, polyolefins and polyvinyl chloride. Thus, as shown in Fig. 1, S indicates the slits, T and R the thickened ribs and F hexagonal openings in the film web shown by dotted lines formed by the shrinkage of the film web. The slit pattern may be such that rows of mutually offset slits are interspersed with rows of non-offset slits, the film web after the shrinkage step having an appearance such as that shown in Fig. 16, the region of the rows of non-offset slits remaining unopened. The slit ends of adjacent rows may overlap considerably, as shown in Fig. 4. The slit patterns may differ considerably (Figs. 5 to 15, not shown) and may include patterns in which the slits are curved. The film web may have a shrinkage direction parallel to the lengthwise direction of the slits in addition to that transverse to the lengthwise direction of the slits. The film web to be reticulated may be tubular, the slits may be formed in the web while it is in the flattened state and the web may subsequently be shrunk while expanded to a tube form. Two or more layers of slit and shrinkable film web may be shrunk together, adjacent individual layers becoming bonded to one another whereby the assembly of film webs becomes converted into a laminated film or sheet. The shrinkable film web may be bonded to a non-textile covering or sheet and after the slitting and shrinking steps a further non-slit non-textile sheet may be bonded to the shrunk web. The bonding may be effected while the shrinkable web is still hot and plastic. The shrinkable film web may be bonded to a non- textile material web with a low shrinkability before the slitting step, the laminate being then slit and shrunk. The non-textile sheet may consist of a plastic, metal foil or paper. The opening of the reticulated film may be filled with an adhesive. The shrinkable film web may contain a foaming agent activated by the shrinking temperature. The shrinkable film web after the slitting step may be positioned between two non-textile layers and caused to shrink by application of heat while it is between the two layers.