초록 ▼

A string zipper is provided for use in the manufacture of material for reclosable plastic bags. The string zipper includes a first profile and a complementary mating profile which, when interlocked and properly attached to the bag walls render the bag easy to open from the outside and hard to open f

A string zipper is provided for use in the manufacture of material for reclosable plastic bags. The string zipper includes a first profile and a complementary mating profile which, when interlocked and properly attached to the bag walls render the bag easy to open from the outside and hard to open from the inside. One of the profiles is formed of polyethylene material that includes an optical brightener to facilitate properly orienting the zipper on a sheet of plastic material. During manufacture of plastic bag material, the zipper is passed through a black light so that the profile containing the brightener can be detected and thus the profiles may readily be distinguished from one another and properly oriented on the sheet material to obtain the desired force differential feature on the final bag.

대표청구항 ▼

In a zipper for use in the manufacture of a reclosable plastic bag, said zipper being of the type having a first profile for attachment adjacent a pull flange area on one side wall of the bag at a top end of the bag and a complementary profile for attachment adjacent a corresponding pull flange area

In a zipper for use in the manufacture of a reclosable plastic bag, said zipper being of the type having a first profile for attachment adjacent a pull flange area on one side wall of the bag at a top end of the bag and a complementary profile for attachment adjacent a corresponding pull flange area on an opposite side wall of the bag, said first and complementary profiles interlocking with each other in a manner so as to require less of a force to disengage the profiles when said force is applied to said pull flange areas than when said force is applied from within the bag, the improvement comprising, said profiles having edges directed toward and away from said pull flange areas: indicia on at least a portion of one of the profiles indicative of the orientation of at least one of said edges of said one profile with respect to its associated pull flange area, said indicia not being visible unless viewed under ultraviolet light.