Nonwoven fibrous mats and methods

Abstract

A water proof membrane containing high strength fibers bonded together with one or more urethanes is disclosed along with the methods of making including wet or dry laying the high strength fibers to form a web, applying an aqueous urethane medium to the web and drying the web and super calendaring the web, or the web can be formed by forming a web by any method from bicomponent core / sheath fibers, the sheath comprising one or more urethanes, followed by super calendaring.

Description

[0001] The present invention involves fibrous nonwoven mats or sheets having particular use as house wraps, packaging, exterior posters, covers, and other similar uses and methods for making these mats. BACKGROUND [0002] House wraps are known. Perhaps the best known is a super-calendered, flash spun, high density polyethylene made by a process such as a process disclosed in U.S. Pat. No. 3,081,519. Others include film laminated woven polypropylene and polyethylene, film laminated spunbond polypropylene and cross-laminated perforated polyolefin films. At least some of these are used regularly as house wraps, but all have some disadvantages. The high density polyethylene suffers from water wicking due to its porosity and open areas around fasteners like nails, staples, etc. Also, high density polyethylene, having very little elasticity, do not grip the fasteners as desired. Film laminates suffer from delamination and to gross damage when the underlying woven polypropylene fibers are s...

AI Technical Summary

Benefits of technology

[0005] The membranes of the invention are a superior house wrap material because the elastomeric nature of the polyurethane forms a sealing relationship with nails, screws and staples that penetrate the mat in the process of building a structure, yet having a permeability to air that permits the membrane to breathe. The holes formed by the penetration of fasteners do not grow, even when subjected to reasonable stress. Membranes of the invention are also superior because they will not pass water through the holes in the membrane around the fasteners because the rubbery nature of the polyurethane matrix in the membrane seals against the penetrating portion of the fasteners. Membranes of the invention also have superior printability and better permanence of printing or dyeing due to being an ether polymer or containing an inhibitor addition, a colorant or a combination of these features.

[0013] 3) Good elongation, toughness, and elasticity, to resist damage when stretched.

Problems solved by technology

The high density polyethylene suffers from water wicking due to its porosity and open areas around fasteners like nails, staples, etc.

Also, high density polyethylene, having very little elasticity, do not grip the fasteners as desired.

Film laminates suffer from delamination and to gross damage when the underlying woven polypropylene fibers are stretched even slightly out-of-plane or even slightly in the cross machine direction.

Cross-laminated film remain subject to installation damage and require perforations to allow for water vapor transmission that weaken the structure further.