Paper making and fiber liberation – Processes and products – Non-fiber additive
Reexamination Certificate
1998-09-10
2001-03-27
Nguyen, Dean T. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-fiber additive
C162S172000, C162S179000, C252S008630, C252S008910, C424S401000, C428S208000
Reexamination Certificate
active
06207014
ABSTRACT:
FIELD OF THE INVENTION
The present invention on the whole concerns a novel composition for a softening lotion used in treating fibers. This lotion is applied on or impregnated into synthetic, artificial, or natural fibers or mixtures thereof, or fibrous structures made in particular from fibers. This lotion, when applied to an absorbent paper product, imparts to the paper a soft slippery feel even though being dry, i.e., not greasy or oily. Furthermore, the invention relates to absorbent paper products treated in this manner.
The invention is applicable to the manufacture of fiber-containing products or structures in the field of papers, non-wovens, textiles and the like.
BACKGROUND OF THE INVENTION
The invention is applicable more especially to the manufacture of paper products such as domestic or sanitary papers. Among these in particular are papers entailing direct contact with the skin and repeated rubbing against the skin, for example disposable paper handkerchiefs, toilet paper or any other paper product for wiping the skin, for removing make-up, dry linen, etc.
People afflicted with colds, influenza or various allergies causing nasal flow will wipe their noses frequently. Oftentimes such people's noses are irritated and red because of skin hypersensitization from this nasal flow. For practical reasons, such people use conventional paper handkerchiefs available commercially in the form of boxed handkerchiefs, also called “facial” tissue, or folded handkerchiefs in small cases. Following several sequential nose wipings with these handkerchiefs, the skin at and around the nose becomes increasingly irritated, even inflamed and painful. Consequently, the surface of these handkerchiefs must be softened in order to limit, even suppress any irritation caused by rubbing the handkerchief surface against the skin. Ideally, the feeling should be the softness offered by a cloth handkerchief that has just been washed and pressed.
In another field, namely that of toilet paper, the same softness is required for repeated contacts with the skin taking place with simultaneous rubbing. In particular as concerns persons suffering from skin irritation in the anal region or in the case of hemorrhoids, a toilet paper with a somewhat rough feel will only further irritate the skin when this paper is pressed against this skin.
Accordingly, endeavors have been underway to generally soften the paper sheets or products, such as the tissue paper webs, using a variety of mechanical or chemical means.
As regards the mechanical means, techniques have been developed to improve in particular the appearance and the surface condition of the paper sheet by endowing it with a more slippery feel. In the case of handkerchiefs illustratively, the sheet is calendered to flatten the crests formed when creping the sheet. Also the sheet surface may be frictionally treated in order to eliminate all roughnesses. However, these approaches often are insufficient. European Patent No. 0 029 269 describes a particular manufacturing procedure for such a sheet wherein the nature of the suspensions of fibers forming the various sheet layers, as well as the combination of these layers among each other, are significant factors for the desired velvety feel. However, this procedure limits the selection of appropriate fibers and entails constraints in the first stages of the wet process phase.
The expression “chemical means” covers any softening composition based on one or several chemical compounds. A distinction may be made between two categories of softening compositions. On one hand, the softening additives or compositions which are directly incorporated into the manufacturing pulp or composition or otherwise are applied to a wet web of paper. And, on the other hand, the softening compositions or lotions which are applied to the surface of a product or a sheet of paper in the dry state, i.e., where prior drying has taken place.
In the first case, these additives as a rule are used as fiber debonding agents and thereby allow flexibilizing of the sheet so made. Many patents have been filed in this field, for example, European Patent Application No. A 0 049 924; European Patent No. B 0 347 176; U.S. Pat. No. 2,944,931; U.S. Pat. No. 5,415,737; and International Application No. WO 95/10661.
European Application No. A 0 049 924 discloses the incorporation of a quaternary ammonium compound and at least one nonionic surfactant selected from fatty acid and fatty alcohol ethylene oxide derivatives into the manufacturing composition in order to achieve a soft absorbent paper. The object of European Patent No. B 0 347 176 is a tissue paper comprising at least one non-cationic surfactant applied to a wet web of paper. However, the surfactant may migrate into the sheet inside and wholly clad the fibers thereby loosening them and decreasing tensile strength. U.S. Pat. No. 2,944,931 discloses a process for improving the softness of toilet paper and its feel consisting in adding a stable aqueous emulsion containing from 1 to 90% by wt. lanolin and from 10 to 99% by wt. of a cationic emulsifier, such as quaternary ammonium salts, to the manufacturing composition. U.S. Pat. No. 5,415,737 concerns a finished soft paper product comprising a vegetal oil-based quaternary ammonium ester compound which is also added to the manufacturing composition. International Application No. WO 95/10661 discloses a manufacturing process for a soft paper with improved feel consisting in added fatty acid ester salts of quaternary amine triethanol as softeners in the fiber aqueous suspensions.
However, on the whole as regards these patents, the product or sheet surface does not offer the desired slippery feature. It is only the product or the web as a whole which is more soft. Moreover, the loss of softening composition during the web manufacturing process is more than trivial.
In the same vein, U.S. Pat. No. 5,279,767 describes more specifically a softening composition comprising a mixture of a quaternary ammonium compound and a polyhydroxy compound. This composition is prepared by mixing in a first stage these two compounds at a high temperature at which they are miscible and then diluting the mixture in high temperature water in order to form an aqueous dispersion of vesicles (or micelles). This composition is preferably incorporated into the manufacturing composition and may be applied to the surface of the formed web, when wet, before drying. It is believed in this patent that the vesicles break up at the time of drying. Most of the polyhydroxy compound so “released” penetrates into the interior of the cellulose fibers and improves the fiber flexibility, the other part being retained at the fiber surface and increases the absorbency rate of fibers. Because of the ionic bonds, the quaternary ammonium compound remains at the surface of the cellulose fibers and thereby the product softness and feel can be improved. This patent does not mention a slippery feel in spite of improved softness. This type of compound addresses an increase in fiber flexibility and it acts substantially within the internal sheet structure, not directly and mainly at the sheet surface.
Variations of this composition are described in other patents such as International Application Nos. WO 94/29,520 and WO 94/29,521.
In the second case, the softening compositions are meant to be applied directly to the product surface or to the absorbent paper sheet surface that was previously dried. Their main function is as a skin emollient.
Many patents illustrate this kind of lotion.
For example, with respect to toilet paper or paper towels used in proctology, U.S. Pat. No. 3,264,188 and French Patent No. 2,376,650 describe lotions providing a fatty feel. The latter patent describes a skin wiping paper product treated with a lipophilic and cleaning emollient, the composition being substantially non-polar and non-aqueous. This emollient may be a mineral oil, petrolatum, paraffin waxes, fatty acids, fatty alcohols, fatty acid esters, derivatives of glycerides, lanolin, polysiloxanes and the like. The
Abribat Benoit
Bret Bruno
Da Silva Marques Maria
De Haut Christian
Leboeuf Jean-Francois
Breiner & Breiner
Fort James France
Nguyen Dean T.
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