1. Field of the Invention
This invention concerns the refolding of a tapered, transversely sealed gussetted bag into a bag having side pleats and a rectangularly shaped bottom.
2. Description of the Prior Art
Thermoplastic material may easily be formed into bags having a tapered or pinched bottom and gussetted side walls. According to such a process, a cylindrical thermoplastic film is expelled from an extrusion die. This cylindrical film may then be gussetted and collapsed flat. The film is then sealed perpendicularly to the edges of the sides thus forming the bottom of the bag. This seal is typically a single seam, usually produced by heating the thermoplastic material at the seam to a temperature which will fuse the two sides of the bag. As there is but a single relatively narrow seam at the bag bottom, the sides gradually taper to the sealed bottom forming a V. The thermoplastic material is then severed, again perpendicularly to the edges of the sides, in order to form a bag top. As the bags thus made are formed from long sheets of plastic, the point of severing, producing the top of one bag, is just below the bottom seam of the next adjacent bag.
While tapered bottom bags made according to the previously described method or a similar method are suitable for many purposes, they have an inherent disadvantage in that they cannot be stood upright as can a square or rectangularly bottomed bag. Grocery bags, such as those used in supermarkets, are preferentially designed with a square or rectangular bottom upon which they may be stood upright, the vertical side panels being in an upright position for easy filling.
The majority of such grocery bags presently in use fulfull this self standing requirement, and are made of paper. Such paper bags have the distinct disadvantage of generally low strength, and have a particularly low "wet strength," that is, an extremely low tensile force resistance capability upon becoming wetted, even if only locally. Coating paper bags with water-repellent or water-proof materials, such as plastics, is excessively expensive.
Paper bags have the additional disadvantage that paper sheets must be secured together at fold lines with a separately applied adhesive. Some types of adhesive used, as well as the bags themselves, attract vermin which are imported into the homes of the purchasing customer, frequently concealed between folds of the paper bag.
Bags made of plastic material have the outstanding advantage of being waterproof, verminproof, resistant to penetration of grease, oils or the like, and sufficiently flexible to follow contours of articles packed within the bag to prevent tearing, for example by corners of square boxes, cans or the like. In spite of these advantages, however, plastic grocery bags have not found substantial acceptance due to their inability to remain open, and erected, for ease of packing without any additional external support devices.
It is an objective of this invention to provide a means for refolding a gussetted, tapered bag so as to produce a bag having a square or rectangular shaped bottom which is capable of standing upright.
Other and additional objectives of this invention will be apparent in light of the entire specification and claims.