Plastic bag having reinforced closure

Claim 2

A plastic bag including a pair of superimposed sheet portions the corresponding edges of which are bonded together to form sealed sides and an open side, means forming longitudinally continuous cooperating male and female interlocking elements on said sheets along the open side of the bag to provide a releasable fastener, and a stiffener rib formed on one of said sheets extending along the open side of said bag, said male and female elements being formed of a first thermoplastic material and said stiffener rib being formed of a second thermoplastic material, said second thermoplastic material being substantially more rigid than said first thermoplastic material to provide lateral rigidity to said bag along the open side to reduce the likelihood of inadvertent opening of said releasable fastener.

Claim 3

The plastic bag as defined in claim 1, wherein said cooperating male and female elements and said stiffener rib are formed integrally with said plastic sheets.

Claim 4

The plastic bag as defined in claim 2, wherein said stiffener rib is disposed in spaced parallel relation with respect to said cooperating male and female elements.

Claim 5

The plastic bag as defined in claim 3, and including another stiffener rib formed on the other of said sheet and extending along the open side of said bag in parallel relation to said first mentioned stiffener rib, Said ribs being slightly offset from one another in a direction parallel to said sheets and arranged in mutually overlapping relation in the closed position of said fastener.

Claim 6

The plastic bag as defined in claim 4, said ribs being substantially rectangularly shaped in transverse cross section.

Claim 7

The plastic bag as defined in claim 1, and including another stiffener rib of said second thermoplastic material formed on the other of said sheets and extending along the open side of said bag in parallel relation to said first-mentioned stiffener rib, said ribs being hook-shaped in transverse cross section and arranged in mutually inverted relation to provide an interlocking connection therebetween when joined together.

Claim 8

The plastic bag as defined in claim 1, and including another stiffener rib of said second thermoplastic material formed on the other of said sheets and extending along the open side of said bag in parallel relation to said first mentioned rib, said ribs each comprising in transverse cross section a first portion projecting laterally of its corresponding sheet and a second portion extending from the distal end of said first portion in a direction parallel to its corresponding sheet, said ribs being arranged in mutually inverted relation and said second portions overlapping one another to provide an interlocking connection therebetween when joined together.

Claim 9

In a bag having sides made of plastic sheet-form material and an elongated plastic releasable fastener joined along corresponding marginal portions of the bag sides to provide a closable opening in the bag, the improvement comprising stiffening means formed adjacent said releasable fastener to impart lateral rigidity to the marginal portions beyond that afforded by the inherent rigidity of the sides of the bag and by the releasable fastener, said stiffening means comprising a rib formed on the marginal portion of one of the bag sides and extending in parallel relation to the releasable fastener and projecting toward the marginal portion of the other of the bag sides, said rib being made of plastic having a stiffness value which is greater than the stiffness value of the plastic of which the bag sides and the releasable fastener are made.

Claim 10

In a bag having sides made of plastic sheet-form material and an elongated plastic releasable fastener joined along corresponding marginal portions of the bag sides to provide a closable opening in the bag, the improvement comprising stiffening means formed adjacent said releasable fastener to impart lateral rigidity to the marginal portions beyond that afforded by the inherent rigidity of the sides of the bag and by the releasable fastener, said stiffening means comprising a rib formed on the marginal portion of one of the bag sides and extending in parallel relation to the releasable fastener and projecting toward the marginal portion of the other of the bag sides, said rib being made of plastic having a stiffness value which is greater than the stiffness value of the plastic of which the bag sides and the releasable fastener are made.