US 3123279 A
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Description (OCR text may contain errors)
March 3, 1964 DAY 3,123,279
PLASTIC BAG Filed May 21, 1962 Inventor Thomas Arnold DAY United States Patent Ofl ice 3,123,279 Patented Mar. 3, 1964 3,123,279 PLASTIC BAG Thomas Arnold Day, Westrnount, Quebec, Canada,
assignor to Du Pont of Canada Limited, Montreal,
Quebec, Canada, a corporation of Canada Filed May 21, 1962, Ser. No. 196,276 Claims priority, application Canada May 25, 1961 1 Claim. (Cl. 22953) This invention relates to plastic bags and more particularly to ventilated plastic bags.
Farm and garden produce are frequently packaged in bags manufactured from thermoplastic materials. At the present time there are two types of bags from which to choose, each having its advantages and disadvantages.
The first type of bag which is in common use today is made entirely from thermoplastic film. This results in an attractive package which is strong, inexpensive and has an exterior which can be printed upon to identify the product and brand. This bag, however, has one serious fault. Many fruits and vegetables require ventilation during storage and a thermoplastic bag of normal manufacture is substantially air tight. To permit some air to circulate through the bag it is common practice to punch holes in the side panels. Since this has a tendency to weaken the bag, the number of holes which can be punched is thus limited and is below that required to provide a desirable level of ventilation.
The second type of bag is fabricated entirely from thermoplastic net. By its very nature this bag is totally ventilated and overcomes the one fault of the film bag. In addition the product in such a bag can be inspected quite readily through the mesh. However, other difficulties present themselves, the most serious being lack of identification. The only area which is available for printing is the overlap film or paper seam at the top and bottom of the bag and this is not adequate.
Another problem posed by this type of bag is damage of the product in the bag by ultraviolet light. Certain produce, potatoes for example, deteriorate rapidly when subjected to light of this wave length. A printed film bag does not permit the rays from the sun or from fluorescent light fixtures to reach the product. But an all net bag does not have this property and this has proven to be a serious disadvantage.
The object of this invention then is to overcome these deficiencies and to provide an inexpensive bag with provision for adequately ventilating and identifying the product.
Other objects and advantages of this invention will become apparent from the following description, it being understood that said description is given by way of illustration and explanation only and not by way of limitation,
since various changes therein may be made by those skilled in the art without departing from the scope or spirit of the present invention.
Referring now to the accompanying drawings:
FIGURE 1 is a plan view of the bag;
FIGURE 2 is a cross section of FIGURE 1 on the line 22;
FIGURE 3 is a perspective view of the bag.
FIGURE 1 shows the thermoplastic film (1) in this case at the back of the bag and the net (2) at the front. The film is shown folded (3) over the net and sealed (4) through the net to itself. This is shown in greater detail in FIGURE 2 and the overall appearance of the bag is shown in FIGURE 3.
It will be obvious that this invention provides a much needed article, a. bag having ample ventilation and a large area suitable for identification purposes. The film can be printed or coloured which in addition to having a very pleasant appearance will prevent the ultraviolet light from striking the product, yet by simply turning the package over, the customer will be able to closely examine the contents through the net. The method of fabrication will result in a bag considerably stronger than the all net bag, as the unperforated film will reinforce the net at the seams.
This present invention can be used with a wide range of thermoplastic materials. An illustrative list from which the materials for both the film and net may be selected would include polyethylene both conventional and linear, nylon, polystyrene, polypropylene, polyolefins, polyesters and blends of polyethylene with polybutene, polyisobutylene and polypropylene.
In addition a combination of thermoplastic film and fibrous net can be used. The film can be selected from the above list of thermoplastic materials and the mesh can be a fibrous material such as paper or cotton.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
In a. plastic bag, the combination of printable thermoplastic film on one side and extruded thermoplastic net on the other, three margins of said film and net being joined together by folding the film over the net and sealing the film through the net to itself.
References Cited in the file of this patent UNITED STATES PATENTS 2,056,804 Potdevin Oct. 6, 1936 2,085,365 Israel June 29, 1937 2,298,421 Salfisberg Oct. 13, 1942 2,689,678 Wendt Sept. 21, 1954 3,040,966 Crane June 26, 1962