US3450809A - Production of voluminous fleece batts - Google Patents

Description

U.S. Cl. 264128 4 Claims ABSTRACT OF THE DISCLOSURE A process for producing voluminous nonwoven fleeces which comprises forming a voluminous-nonwoven batt of fibers, at least some of which have been waterproofed prior to batt formation, and thereafter impregnating the voluminous batt with an aqueous dispersion of binder. The waterproofing of the fibers provides the batt with a voluminous nature following impregnation with the binder dispersion.

This invention relates to the production of non-woven fabrics. It more particularly refers to the production of voluminous, relatively low bulk density, non-woven batts. It is, of course, well known to produce non-woven fabrics. This is generally accomplished by randomly disposing staple fibers or continuous filament or even yarns onto a suitable surface and applying a binder to the fibers, such that the product fabric will have at least some degree of dimensional stability. It is known to subject the fibrous batt, prior to impregnation with binder, to a needling process, should such be desired to improve the resistance of the batt to planar delamination.

It is often desirable to produce batts of non-woven fabric having a relatively low bulk density. These materials are particularly well suited for use as air filters or sound absorbing applications.

In the past, non-Woven fibrous batts have been made with various degrees of interstitial space, such that the bulk density of the batt can be significantly varied. Binding agents have been applied by impregnation with aqueous dispersions thereof. It has been the experience of the art that impregnation with aqueous binding agents results in a significant reduction in the thickness of the batt, since the water causes the inter tangled fiber structure to collapse to a greater or lesser degree. The production of such thin sheets of material by impregnation of voluminous non-woven batts with aqueous dispersions of binding agents is shown in U.S. Patents 2,719,802, 2,719,803 and 2,719,806.

It has been sought to improve the process of impregnation of voluminous non-woven batts with a suitable binding agent in order to retain the voluminous character thereof. Since water dispersions of the binders have proved inadequate to retain this voluminous structure, the art attempted to employ nonaqueous solvents and dispersants, and in particular to use organic materials. Impregnation of voluminous non-woven batts by means of organic dispersions of suitable binding materials has proved effective to retain the voluminous character of the nonwoven batt, since the organic dispersant appears not to have the tendency to cause the fiber content of the batt to collapse under itself.

It will be appreciated, however, that the use of organic dispersants, as opposed to aqueous dispersants, leads to difficulties in processing as well as increases the expense of producing non-woven fibrous batts. Thus, for example, organic materials suitable for use as dispersants should nited States Patent O 3,450,809 Patented June 17, 1969 be recovered after impregnation, cleaned and recycled for further use in the impregnation system. This additional processing generally entails additional capital expenditures for the equipment in which the process is carried out, as well as entails the use of chemical processing technology in the purification steps, which were not necessary in the case of aqueous dispersants. This, of course, adds to the difficulties encountered in carrying out the process. Further, many organic dispersants or solvents are flammable materials and therefore the mere handling of these materials in a fiber processing plant presents hazardous conditions, which the art would like to avoid, if at all possible.

It is therefore an object of this invention to provide a novel process for the production of voluminous nonwoven fibrous batts.

It is another object of this invention to provide a process for the production of voluminous fibrous batts containing binder therein, wherein the binder is not applied by means of an organic carrier.

Other and additional objects of this invention will become apparent from a consideration of this entire specification including the claims appended hereto.

In accord with and fulfilling these objects, this invention resides, in one of its broad aspects, in the impregnation of voluminous, non-woven, fibrous batts with an aqueous dispersion of a suitable binder under such conditions that the water present will not cause the nonwoven fibrous structure to collapse and thereby increase in bulk density. In order to accomplish the purposes of this invention, the fibers constituting the non-woven batt are subjected to a waterproofing treatment prior to the impregnation step referred to above.

Fibers which are useful in this invention can be selected from any of the commercially available natural or synthetic materials, for example, cellulosics, wools, and linens. In particular, it is preferred to utilize cellulosic fibers and blends of cellulosics and other fibers.

The waterproofing agent is suitably applied directly to the fibers prior to the production of the non-woven batt. Any of the commercially available waterproofing agents, such as, for example, a mixture of a parafiin emulsion and aluminum-triformate, or a partially etherified melamine-formaldehyde resin, in which a part of the ether groups is substituted by fatty acids, are suitable for use in this invention. These products are available under the trade names Contraqua-Supra or Phobotex FT respectively.

The following examples illustrate practical forms of the invention and are not to be construed as limiting the scope of the invention in any manner.

EXAMPLE I Cellulose-wool (22 denier, mm.) are soaked with a mixture comprising 10 parts of a mixture of a paratfin emulsion and aluminum triformate, parts water, spindried to a moisture content (Water content as percent of dry weight) of percent and dried at a temperature of C.

A fleece of 200 grams per square meter is carded from fibers first treated in this manner and then sprayed on both sides with a mixture comprising 100 parts of a crosslinkable, 50 percent acrylate resin dispersion, 2 parts ammonium oxalate; and 400 parts water; resulting in a mat with a final weight of 280 grams. The product obtained in this manner has a thickness of about 20 mm.

A similarly produced batt, impregnated in the same way, except for the fact that the fibers of the batt were not subjected to a prior waterproofing treatment, resulted in a binder-impregnated fibrous product having a thickness of only about 4 to 5 mm.

3 EXAMPLE II The same fibers as set forth in Example I are soaked in 6 percent waterproofing mixture of a partialy etherified melamine-formaldehyde resin, in which part of the ether groups is substituted by fatty acids, spin-dried to 100 percent moisture content and dried at 105 C.

The spraying mixture comprises a 20 percent dispersion of a chlorine-containing, film-forming compound, wherein 20 percent (calculated on the solids content of the spray mixture) antimony trioxide is added.

Once more, a 200 gram-fleece is made from the pretreated fibers. This is then sprayed with the spraying mixture, giving a final weight of 280 grams. The obtained mat has, along with its volume, the additional property that is is difficult to set afire.

EXAMPLE III A fiber mixture comprising 70 parts of the cellulosewool prepared according to Example II; and 30 parts of a polyvinyl chloride fiber is carded to a fleece of 150 grams per square meter and sprayed on both sides with a 20 percent mixture of a cross-linkable acrylate resin dispersion to which has been added 20 percent antimony trioxide and 1 percent ammonium oxalate; (percentages calculated on the solids content); giving an end product with a weight of 210 grams. This mat is marked, besides by its volume, by its being diificult to set afire.

What is claimed is:

1. In the process for producing voluminous, non-woven fleece batts which comprises forming a voluminous batt of fibrous material and impregnating such batt with an aqueous dispersion of a binder for such fibrous material; the improvement comprising the applying of a waterproofing material to said fibrous material prior to forming said batt to maintain the voluminous nature of said batt following the impregnation of said batt with said dispersion of binder.

2. Process as claimed in claim 1, wherein said fibrous material is cellulosic.

3. Process as claimed in claim 1, wherein said fibrous material is a cellulosic-wool blend.

4. The improved process as claimed in claim 1, including the step of mixing about 70% waterproofed fibers with about 30% nonwaterproofed fibers and forming said batt of said mixture.

References Cited UNITED STATES PATENTS 3,015,595 1/1962 Moser et a1. 264128 3,025,203 3/1962 Leupold et a1. 264-128 ROBERT F. WHITE, Primary Examiner.

I. R. HALL, Assistant Examiner.