In 1951, a company called Flexigrip, Inc. was formed to develop and market a plastic zipper, by the same name, based on a set of patents, which it had purchased, of which the inventor was Borge Madsen.
The initial products for the Flexigrip and other plastic zippers (such as the sliderless zippers (toptite) that were developed by Flexigrip) were looseleaf binder inserts and flat briefcases.
Thereafter, the marketing efforts were directed at packaging products in plastic zipper bags, which turned out to be the principal market for the Flexigrip, Inc. products. In 1961, Flexigrip, Inc. obtained from a Japanese company, Seisan Nippon Sha, who invented the Minigrip-type plastic zipper bag, exclusive manufacturing and selling rights for the United States, based on a series of plastic zipper Seisan patents.
A company by the same name was formed to produce and market Minigrip bags. In or about 1964, Minigrip, Inc. negotiated an exclusive license for the grocery trade (supermarkets) with Dow Chemical Company for the Minigrip product. Dow named their product Ziploc and started to market it in 1968.
It turned out to be enormously successful. In 1978, Minigrip was acquired by Signode, Inc. and became a subsidiary of that company. In 1986, Signode and Dow formed a company, namely Zippak, to develop zipper bags for food products. In 1987, ITW acquired Signode, and Minigrip became a subsidiary of ITW. In 1991, ITW acquired Dow’s interest in Zippak so that Zippak became a fully owned subsidiary of ITW.