Flexible bags – Free-standing
Patent
1993-01-29
1994-10-04
Garbe, Stephen P.
Flexible bags
Free-standing
383119, 493194, B65D 3016, B65D 3020
Patent
active
053520432
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a novel self-supporting bag having good stiffness, excellent stability in its self-supporting properties and excellent shape holding properties and easy handling, and to a method of production thereof and as well as apparatus production thereof.
DESCRIPTION OF THE PRIOR ART
Self-supporting bags which can stand self-supported without falling down when the bags are charged with contents have been known. Examples of such known self-supporting bags are:
a so called doipack made by putting together a film constituting the trunk part and a film constituting the bottom part after folding them, followed by sealing the bottom part to a curved shape (to a shape of an arc);
a bag made by sealing parts for the bottom part made by folding two sheets of film forming the trunk parts faced with each other in such a way that films for the bottom part are combined together with an angle to form a single piece and the bottom face takes a square shape (for example, Laid Open Japanese Patent Application Showa 57-46750);
a bag made of a single sheet of film by folding the part forming the bottom to a W shape and then sealing the side part with an angle to form a square bottom part so that the bag has the self-supporting property (for example, Laid Open Japanese Patent Application Showa 56-123255); and
a bag made by folding the part forming the side wall part of the bag with the gazette folding so that the bag has the self-supporting property (for example, Laid Open Japanese Patent Applications Showa 54-8072 and Showa 60-172656).
Among these bags, the doipack bag which is provided with the self-supporting property by filling the bag with a liquid material and the bag which has the bottom part of a square form are generally utilized. The bags in which the side wall part is made with the gazette folding are utilized mainly in combination with paper boxes or mainly for containing powder materials.
However, because the conventional self-supporting bags have insufficient stiffness at the upper parts of the bags in the filled condition, they have problems that stability and shape holding property are not sufficient and that amount of discharge of the content is not easily controlled because film of the trunk part is bent by the weight of the content during the discharge of the content.
For solving the problems described above, the film constituting the trunk part can be made thicker to give it more stiffness. However, this method has problems that a bag improved by simply increasing the thickness of the side walls is not easily handled as a bags and it is more like a stiff container than a bag, thus the favorable properties of bag containers such as flexibility being lost and that cost of producing the bag is increased.
As a method other than increasing thickness of the film, a method of effectively utilizing the sealed parts of the bag is known but this method has a limitation caused by the structure of the bag and has not been actually effective for solving the problems so far. Still another method was proposed in which structure of the self-supporting bag itself is changed in such a way that a constriction is formed at the trunk part of the bag to provide the bag with the self-supporting property (Laid Open Japanese Patent Application Showa 62-16345). However, the problem during the discharge of content remains unsolved by this method.
SUMMARY OF THE INVENTION
Extensive investigations undertaken by the present inventors with the objects described above lead to a discovery that a self-supporting bag having good stiffness, excellent stability of the self-supporting property and excellent shape holding property can be produced by making both of the part constituting the trunk and the part constituting the bottom of the self-supporting bag with a multilayer plastic film, by forming the inner layer of the multilayer plastic film with a heat adhesive layer and by forming a section comprising convex parts and concave parts adjacent with each other and a surface having linear r
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Hirose Shizuo
Takagaki Tadao
Tonouchi Ikuo
Garbe Stephen P.
Sumitomo Bakelite Co., Limited
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