Point-bonded jet-softened polyethylene film-fibril sheet

Claim 1

A process for preparing a dyed nonwoven fabric that is particularly useful in a disposable protective garment of the type worn by asbestos workers comprising forming an aqueous mixture of a disperse dye and a hydrophilic finish and contacting the nonwoven fabric produced by passing a lightly consolidated, flash-spun polyethylene plexifilamentary film-fibril sheet having a unit weight in the range of 25 to 50 grams per square meter through two successive nips, each nip being formed between two rolls, one of which is a heated metal roll having hard bosses on its surface and the other roll having a resilient surface the Shore A durometer hardness of which is in the range of 60 to 70, the heated metal roll of the first nip contacting one surface of the sheet and the heated roll of the second nip contacting the other surface of the sheet, the bosses of the heated metal rolls forming a repeating regular polygon pattern in which the bosses are spaced in the range of from 4.8 to 7.1 bosses per centimeter and number in the range of 29 to 62 bosses per square centimeter, the bosses having a height that is in the range of 1.2 to 1.8 times the thickness of the sheet being contacted and having a total cross-sectional area at their tips equal to about 4 to 7 percent of the sheet area being treated, the bosses of the second nip being out of register with the bosses of the first nip, each nip applying a load in the range of 9 to 21 kilograms per centimeter of width to the sheet, to form a point-bonded sheet that is then subjected to high energy jets of water supplied from multiple closely spaced orifices having diameters in the range of 0.08 to 0.18 mm to impart to the sheet an energy-impact product in the range of 0.26 to 0.8 megaJoule-newtons per kilogram with the mixture and drying the fabric.