Ziplock is a brand of reusable, re-sealable zipper storage bags and containers originally developed and test marketed by The Dow Chemical Company in 1968, and now produced by S. C. Johnson & Son. The plastic bags and containers come in different sizes for use with different products. The brand offers sandwich bags, snack bags and other bags for various purposes.
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 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 product. It turned out to be enormously successful.
At that time, plastic bags were being produced in 25 countries at a line speed of 30 feet per minute, but none were being sold to consumers because they were too expensive to produce. Dow assigned one of their inventors, R. Douglas Behr, to develop a high-speed, efficient process. Having little prior experience in plastics, the task was daunting for Behr but he passed everyone in the world within a year. As he improved the process and increased line speeds to 60, then 90, then 150 and finally 300 feet per minute in 1972, he had to design new equipment. Some was patented and some was kept as Trade Secrets by Dow.
Eventually, other research and production personnel contributed to the process development, but Behr continued to be the leading researcher until he retired in 1993 as a senior Associate Scientist. At that time the research building was "Dedicated in Recognition of the Distinguished Career of R. Douglas Behr".
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. Zippak produces plastic zippers for the food packaging market. Among Ziploc and Zippak's competitors are Presto, a subsidiary of Reynolds, and Pactiv. From the time of inception till today, Flexigrip/Minigrip/Zippak/Dow/Dow Brands have obtained over 300 patents for plastic zippers, zipper bags, and methods and machinery of producing the same. In 1995, Hefty came out with a sliding zipper bag.
In 1997 Dow Chemical sold the rights of DowBrands, which included Ziploc, to S. C. Johnson for between .3 and .7 billion. Zip-Pak developed Polypropylene compatible zippers in 2003.
More info: http://www.hiplasticbags.com