US3113038A - Nonwoven fabric coating containing propylenimine-cross linking agent for carboxyl containing acrylic polymer - Google Patents

Description

United rates Fatent 3,113,038 NQNWQVEN FABRIC COATENG CGNTARNENG PROPYLENIMZNE-CRUSd LHNKENG AGENT FOR CARBQXYL CGNTAINHNG AQRYLHQ PGLZMER Charles I. Lattarulo, New York, and Eohn .F. P. Lurzi,

Freeport, N.Y., assignors to later-chemical Corporation, New York, Nfnfl, a corporation of (Elsie No Drawing. Filed liars. 1?, 11961, No. 83,611 2 Claims. (Chill-14d) This invention relates to nonwoven fabrics and to a method of making them with a binder comprised of linear acrylic interpolymers and alkylene imines. Low cost nonwoven fabrics having soft hand as well as good fastness to washing and dry cleaning are in considerable demand. The attempt to produce such materials is beset by many problems. Binders are all-important factors in determining the properties of the finished fabric. At present synthetic rubber latices, particularly butadienestyrene and butadiene-acrylonitrile types, vinyls, acrylates, starch, gum casein and the like constitute the binders in use. 'Urea and melamine resins are also added to latices in quantities up to about of the latex Weight in order to impart thermosetting properties and to improve Washiastness and solvent resistance. These fabrics have found applications in the fields of disposable items, padding and packing, shoe fabrics, interlining for clothing, containers, tapes, toys, filters, vinyl fabric backing, etc. Thus far acceptability in the durable outer wear garment field has been less than enthusiastic due to the lack of nonwoven fabrics having the softness and drapab-ility of woven goods together with good wet and 'dry cleaning resistance.

There have been many attempts to make such fabrics, chiefly by combining thermosetting resins with soft polymers in emulsion form in order to obtain a crosslinking effect with consequent improved durability and strength. The difficulty with these types has been their poor drapability and hand. Generally speaking, as strength and durability was thus gained, the stiffer the cloth became, and contrariwise, the more flexible the material, the poorer the tensile strength.

It is the consensus of opinion that significant progress in the field of nonwoven fabrics will depend almost ontirely on the development of new and better binders.

Of the materials in use, styrene-butadiene binders, although flexible and elastic, have poor stability to light and poor wet and dry cleaning properties. Cleaning durability is much better with acrylonitrile-butadiene binders but they discolor, become odonous on aging, and much of the binder mi rates to the surface during bonding, leaving the fabric weak in the center. The latter defect makes delarnination a common hazard. Starch, gums, casein, and the like impart brittleness, poor hand, and poor wet strength. The vinyl polymers produce stilf, tough fabrics suitable for some uses, such as innersoles, shoe interliners, and other applications where a comparatively low flexibility is acceptable. Acrylic latices otter excellent ligiht stability and good band but their fastness to Wet and dry cleanin is. only fair. The cleaning properties are improved somewhat by combining the acrylic latices with minor amounts of urea resins or melamine resins. This recourse, however, has the limitations pointed out above.

3d lhddd ice it has now been discovered that nonwoven fabrics of good wrashfastness, good dry cleaning fastness, and having excellent hand and drapaoility can be obtained by using as binders a blend of the latices of acrylic interpolymers containing a minor amount of carboxyl groups with a small amount of an alkylene imine, especially propylenimine, in aqueous solution. This is a surprising development. Polyfunctional imines and various other crosslinking agents have been combined with latices containing reactive groups, but the crosslinlring; action is at least understandable in such cases. It now appears that imines considered to be monofunctional produce at least some results hitherto ascribed only to poly functional compounds. The explanation for this phenomenon is not known.

In the examples the parts and percentages are on the weight basis.

Example 1 A binder was made by blending 69 parts of a reactive acrylic latex with 3 parts of an 8.4% aqueous solution of ropylenimine and 37 parts of water. The latex was comprised of a linear interpolymer of Z-ethylhexyl acrylate, 13% acrylonitri-le, and 2% itaconic acid. The binder had a pot life of at least 12 days at room temperature.

Example 2 A random web of viscose rayon fibers was passed through the binder and the excess liquor squeezed out between padding rollers using 5 and 10 pounds of pressure. The padded fabric was can dried for 23 minutes at 240 F., sufficient for drying and then cured 3 minutes at 360 F. The dry pickup amount to 40 to 50% based on the weight of dry fabric. The nonwoven fabric so prepared had notable resistance to alkaline wash and solvent. The hand was soft and the drape was good.

The composition of the latex may be varied consider ably without seriously impairing the benefits of the novel binder. The monomer containing the free carboxyl group is effective in the range of from about 1 to 6% of the total Weight of monomers. Acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, and itaconic acid are suitable. The major constituent may be any alkyl ester of acrylic acid, the ralkyl group having about 1 to 12 carbon atoms. The third ingredient is preferably acrylonitrile, although latices such as Hycar 1571, a copolymer of 1,3 butadiene:acrylonitrile:methacrylic acid, are operable in the ranges of about 10-20 percent. Propylenimine is preferred as the additive, although ethylenimine and derivatives of greater carbon content are operative.

Curing time is not critical. The preferred treatment is given in the examples. Lower temperatures are effective when the curing time is prolonged, and higher temperatures shorten the time required. These variations in curing schedules are well known in the coating art.

What is claimed is:

1. A nonwoven fabric comprising a web of overlapping intersecting fibers uniformly bonded with a binder formed in situ by reacting a linear acrylic polymer containing a minor amount of carboxyl groups with propylenimine.

2. A nonwoven fabric comprising a web of overlapping intersecting fibers uniformly bonded with a binder 4- formed in situ by reacting a blend of (A) about 60 parts amounts ranging from about 20 to about 50 weight perby Weight of a latex comprising about 60 parts by Weight cent of file finislhed fabric. of water and about 40 par Ls by Weight of a dispe rsion of a linear copoiymer of about 85 parts by weight of Z-ethy l- References flied in the file of 1118 Patent hexyl aoryla'te, about 13 parts by weight of acrylonitrile, 5 UNITED STATES PATENTS and about 2 parts by weight of itaconic acid, (B) about Q i Q a 0.25 part by Weight of propyien imine, and (C) about 40 am by weight of Water, file binder being present in

Claims (1)

1. A NONWOVEN FABRIC COMPRISING A WEB OF OVERLAPPING INTERSECTING FIBERS UNIFORMLY BONDED WITH A BINDER FORMED IN SITU BY REACTING A LINEAR ACRYLIC POLYMER CONTAINING A MINOR AMOUNT OF CARBOXYL GROUPS WITH PROPYLENIMINE.