US3459592A - Textured non-woven fabrics - Google Patents

Description

Aug. 5, 1969 R. R. ALEXANDER TEXTURED NON-WOVEN FABRICS Filed March 25, 1966 States Unite 4 Claims ABSTRACT OF THE DISCLOSURE Short fibers of paper-making length are agitated in water to form agglomerates or fibrous aggregates, and a binder is added to the aqueous suspension. The mixture is then applied to a nonwoven web of textile-length fibers, resulting a decorative coating of discrete and spacedapart short-fibered aggregates.

This invention relates to the surface ornamentation of bonded non-woven fabrics. More particularly, it relates to a process for imparting a pebbled texture to the surface of such fabrics, to methods for obtaining speck-dyed effects, and to the products of such a process.

Bonded no-woven fabrics are commonly made by subjecting a carded, garnetted, or air-laid web of textilelength fibers to a wet process wherein they are saturated with a polymeric binder, usually in the form of an aqueous emulsion, latex, or similar dispersion. Due to the small dimensions of individual textile-length fibers, and to the fact that in assembling the fibers into a fleece it is customary to distribute the fibers uniformly so as to avoid weak places in the product, bonded non-woven fabrics in general have a flat, planar look, resembling a sheet of paper. They lack the highlights and surface interest inherent in most woven fabrics, which are due to the natural over-and-under yarn interlaeings and the accidental or deliberate variations in yarn thickness found in the latter.

It is therefore a primary object of this invention to produce a bonded non-woven fabric with enhanced surface interest.

It is also an object of this invention to produce a bonded non-woven fabric with a nubby or pebbled surface resembling woven fabrics.

Other objects of the invention will appear more fully in connection with the following description and drawing, in which the figure is a schematic plan view of one embodiment of this invention.

It has now been discovered that if aggregates of short fibers, defined more fully below, are added to the liquid bonding agent used to unify the textile-length fibers of the basic web, such aggregates of properly prepared and of appropriate size are deposited in random fashion on the surface of the fibrous web by a sort of filtering action, thus leading to a bonded non-woven fabric with an interestingly varied surface texture.

It is well-known that it is difficult, if not impossible, to disperse textile-length fibers (that is, fibers over one-half inch in length) in aqueous binder media with any degree of uniformity, since the fibers, with even moderate degrees of mechanical agitation, tend to clump together into a unitary mass. At the other end of the scale, fibers in an extremely fine state of subdivision such as wood flour will merely disperse uniformly in a binder, thereby increasing its viscosity, and when employed in the process of this invention lead to smooth, uniform products lacking in the surface texture which it is desired to achieve.

I have found that if short fibers of paper-making length, conveniently cellulose fibers, are agglomerated into particles of a certain size, the agglomerates can be incorporated into an aqueous polymeric binder dispersion without atent O increasing the viscosity excessively, and that such a dispersion can then be used to bond webs of textile-length fibers by conventional methods such as flooding or rollercoating. Such agglomerates will be referred to herein as short-fibered aggregates.

In general, the optimum size of such aggregates will depend on the diameter (denier) of the textile-length fibers in the web to be bonded, and on the inter-fiber spacing of such fibers. When dealing with conventional fibers such as cotton, or viscose rayon of 1.5 to 10 denier, I have found that a convenient and suitable range is found in a dispersion wherein the aggregates range from 0.1 to 25 square millimeters in area, with the majority of the aggregates ranging at around 10 square millimeters. The shhort-fibered aggregates will in some cases tend to be three-dimensional: the above range of dimensions, therefore, is to be interpreted as the area of maximum projection on a planar surface. For optimum decorative effect, I have found that the area occupied by these shortfibered aggregates should be only a minor portion of the total area of bonded non-woven fabric to which they are applied. Individual aggregates are preferably separated from each other by an average distance which is from two to four times the average diameter of the aggregates, especially satisfactory results being obtained when between 5% and 20% of the total area of the surface of nonwoven fabric is taken up by short-fibered aggregates adherent to said surface.

Short-fibered aggregates may comprise knots or clusters of rayon or cotton flock, mechanically agglomerated as by milling or frictional tumbling together. A more convenient source, however, is provided by the disintegration into small and generally fiat or leaf-shaped particles of a preformed sheet of short cellulose fibers such as are found in a sheet of cellulose wadding. The longer the fibers used, the more irregular and difiicult to handle are the agglomerates derived therefrom. A convenient fiber length range has been found to be from 0.1 millimeter to 5 millimeters.

Referring to the figure, a bonded non-woven fabric 10 is shown as comprising textile-length fibers 12, bonded to each other by a conventional polymeric binder, the surface of said non-woven fabric being ornamented by a mul tiplicity of randomly-spaced and randomly-shaped shortfibered aggregates 14. The preparation of a non-woven fabric of this nature is illustrated by the following example.

Example In a Waring Blendor, 5 parts of cellulose wadding, shredded into 1% inch pieces, are agitated with 40 parts of water for 10-15 minutes until a uniform slurry is obtained, consisting of water-dispersed short-fibered aggregates of cellulose fibers. To this is added, with agitation, the following:

2 parts Triton X- (Rohm and Haas wetting agent) 0.5 part Tamol 731 (Rohm and Haas dispersing agent) parts 45% dispersion Rhoplex E-214 (Rohm and Haas polyacrylic emulsion) 100 parts 50% Hycar 2600 83 (B. F. Goodrich polyacrylic emulsion) 12.5 parts of 10% solution of Acrysol G.S. (Rohm and Haas polyacrylic thickening agent) 2 parts 5 0% paste of phthalocyanine blue pigment.

The binder mixture containing suspended short-fibered aggregates was then metered to the upper of a pair of nip rolls, through which pair of rolls there was passed a carded web of 3 denier, 1%; inch rayon fibers weighing 30 grams per square yard. The wet pick-up of binder plus aggregates was 100%. The wet web was dried on a set of steam-heated cans, and then cured at 300 F. for 3 minutes.

The resulting product, resembling the figure, was a bonded non-woven fabric, blue in color, with an interest ing pebbled or hubby upper surface.

In case the fibrous web of textile-length fibers is too weak internally to be roller-coated with binder without plucking or distorting, it may be spray-bonded in a preliminary bonding process to give it strength. A convenient procedure in such a case is to prepare the binder suspension of the example in two parts, one with short-fibered aggregates and one without. The binder without aggregates is then applied to the textile-length fibrous web, as by spray coating or by a double-screen saturator, both techniques being well-known in the art and needing no elaboration here. The wet web is then dried to effect unification and strength, after which the portion of binder containing the short-fibered aggregates is applied as by roller coating or knife coating.

The relative weight proportions of fiber in the textilelength fibrous web and in the short-fibered aggregates may vary within wide limits, depending on the depth of texture which it is desired to impart to the surface. In order to get a readily fiowable binder mixture, however, it is convenient to have the short-fiber content not more than 40% of the total fiber content of the final product, between and 40% being a suitable range. In the preferred products of this invention, therefore, the major fibrous constituent is the textile-length fibers, with a minor portion of short fibers.

In the example, the blue pigment added to the binder suspension is incorporated into the binder, so that a blue non-woven fabric results, with scattered surface fiecks of darker blue where the short-fibered aggregates have 10- cally increased the opacity of the fabric. It is also possible to use short-fibered aggregates of dyed or pigmented fibers with a colorless or tinted binder, and to apply such aggregates in binder suspension to a web of textile-length fibers which are either white, or which have been colored as by pigment or dye inclusion in their manufacture. If the short-fibered aggregates and the textile-length fibers are of different chemical composition, as for example short cellulose fibers bonded to a nylon web, selective dyes will dye one of the fibers and not the other. Other variations,

such as mixed dyeing techniques which in one bath will dye chemically diiferent fibers different hues, will readily occur to those skilled in the art.

In addition to the surface-texturing described above, other benefits accrue from the practice of this invention. The short-fibered aggregates are in general less expensive than textile-length fibers, so that increased absorbency can be built into non-woven fabrics at modest cost. Additionally, the surface addition of short-fibered aggregates increases the opacity and the firmness of hand of non-Woven fabrics to which the aggregates are bonded.

Having thus described my invention, I claim:

1. A surface-textured bonded non-woven fabric comprising a major portion of textile-length fibers bonded together with a polymeric binder, and adherently bonded to at least one surface thereof a multiplicity of randomlyspaced and randomly-shaped short-fibered aggregates of between 0.1 and 25 square millimeters in area giving said one surface a pebbled texture.

2. The product according to claim 1 wherein the shortfibered aggregates comprise cellulose fibers of papermaking length.

3. The product according to claim 1 in which the textile-length fibers comprising the major portion of the fabric and the short-fibered aggregates comprising the minor portion of the fabric are of contrasting colors.

4. The product according to claim 1 wherein said aggregates cover between 5% and 20% of the total surface area of the non-woven fabric.

References Cited UNITED STATES PATENTS 1,994,893 3/1935 Magoon 11725 2,673,819 3/ 1954 Wendell.

3,012,911 12/1961 Moser.

3,169,885 2/1965 Golodner et al. 117135.5

3,222,208 12/1965 Bertollo 117135.5 X

WILLIAM D. MARTIN, Primary Examiner H. I. GWINNELL, Assistant Examiner U.S. Cl. X.R. 117-161; 260-41

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