Flexible bags – Wall details – Specified seam structure
Patent
1989-12-13
1993-04-27
Elkins, Gary E.
Flexible bags
Wall details
Specified seam structure
383120, 383903, 428156, 428167, 493227, 493240, B65D 3300, B65D 3010
Patent
active
052056503
DESCRIPTION:
BRIEF SUMMARY
When forming bags and other articles from orientable thermoplastic polymeric film material, various ways are known and used for ensuring that the film material has adequate strength for the purposes to which the bag will be subjected. Despite this, there is always a risk that the final article will rupture during use when it is subjected to sudden forces. For instance a sack that has been filled with powder or granules may rupture when dropped. The tendency is greater with relatively rigid polymers (considering the modulus of elasticity) such as polypropylene or high density polyethylene than with less rigid polymers such as low density polyethylene, but even the low rigidity polymers have a tendency to rupture when subjected to impact.
It would be desirable to find a way of reducing the tendency for the film material (or article formed from it) to rupture under impact, and to increase the energy absorption properties of the article.
The present invention is concerned with ways of spreading the tension and other forces in a film material in such a way as to minimise the risk of rupture.
In some instances, it would be desirable for a major proportion of the article, or even the entire article, to be modified in this manner. For instance it can be desirable to modify strapping formed from orientable film material, especially strapping for parachutes, in order to minimise the risk of rupture under impact or to reduce the impact on the load which the strapping is intended to carry, or for similar reasons it can be desirable to modify the entire surface area (or parts of the entire surface area) of large sheets, such as the hood of a parachute.
In other cases it is desirable to modify minor proportions of the film in selected areas. Thus particular problems arise with sacks or bags since generally there is a particular zone in the bag at which the bag is liable to start rupturing, and I refer to this as the rupture zone. It would be particularly desirable to modify the bag in the rupture zone. Once rupturing has been initiated, the rupturing is liable to be propogated out of the rupture zone. The rupture zone, for any particular construction of bag, can be postulated from theoretical considerations or, in a more practical aspect, can be determined experimentally by dropping some full bags.
The rupture zone is often associated with a seam in the bag in that the film material adjacent to a seam is often more liable to rupture than film material elsewhere in the bag. It appears that the act of forming the seam can adversely affect the properties of the film material in the areas adjacent to the seam. However it should be noted that the rupture zone may not extend across the entire length of the seam since in a conventional bag the rupture zone may be located primarily in the area mid-way between the ends of the seam.
When the bag is a gussetted bag that has an end seal and that comprises opposed outer faces or panels interconnected at their side edges by side gussets, there tends to be a particular rupture zone at the junction between the side gussets and the seam.
A bag may have more than one rupture zone. For instance if the bag is seamed at top and bottom then there will generally be a rupture zone associated with each seam (and at which rupture is likely during edge drops) and if the bag has side gussets then there will generally be a particular rupture zone also at the junction between the side gussets and the seam (and at which rupture is likely during flat drops).
It is of course very well known to subject the film material from which the bag is made to various orientation and other treatment steps so as to impart optimum properties to it but conventionally the film throughout the entire bag is of substantially uniform properties. It is also well known to emboss the surface of the film either for visual appearances or to facilitate stacking of the film. However conventional overall embossing techniques do not give the improvements that would be desirable.
Orientable thermoplastic polymeric film material acc
REFERENCES:
patent: 2083352 (1937-06-01), Smithe
patent: 2723936 (1955-11-01), Ryan
patent: 3018015 (1962-01-01), Agriss et al.
patent: 3232516 (1966-02-01), Arslanian
patent: 3605374 (1971-09-01), Mueller et al.
patent: 3743172 (1973-07-01), Ackley et al.
patent: 3832267 (1974-08-01), Liu
patent: 3911187 (1975-10-01), Raley
patent: 4000352 (1976-12-01), Hollenbeck et al.
patent: 4076121 (1978-02-01), Clayton et al.
patent: 4343848 (1982-08-01), Leonard, Jr.
patent: 4401427 (1983-08-01), Benoit et al.
patent: 4465729 (1984-08-01), Cancio et al.
patent: 4563374 (1986-01-01), Treber et al.
patent: 4566252 (1986-01-01), Watanabe et al.
patent: 4946430 (1990-08-01), Kohmann
Daniel William J.
Elkins Gary E.
LandOfFree
Tubular bag with shock absorber band tube for making such bag, a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tubular bag with shock absorber band tube for making such bag, a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tubular bag with shock absorber band tube for making such bag, a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2322453