Biodegradable fabric softening compositions based on a...

Cleaning compositions for solid surfaces – auxiliary compositions – Auxiliary compositions for cleaning – or processes of preparing – Textile softening or antistatic composition

Reexamination Certificate

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Reexamination Certificate

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06194374

ABSTRACT:

This invention relates to fabric softening compositions and/or articles for applications to washed laundry during rinsing and/or drying cycles, and to a method for preparing same. More particularly this invention relates to such compositions and articles that include as fabric softening components higher fatty acid esters of pentaerythritol, of pentaerythritol oligomers, or of ethoxylated derivatives thereof, all of which may be designated herein as PEC (for pentaerythritol compound) in combination with a clay carrier of the montmorillonite type, preferably, bentonite and a polyphosphonate compound as herein defined, and wherein such compositions and/or articles do not contain quaternary ammonium salts as fabric softener.
Fabric softening compositions and articles have long been employed to make washed laundry items softer to the touch and more comfortable to the wearer. Such compositions include solutions, emulsions, and particulate and powder products and such articles include paper strips that have been impregnated with fabric softener. The fabric softeners of choice for most commercial products have usually been quaternary ammonium salts, such as dimethyl ditallowyl ammonium chloride, and emulsions of such softener have been added to the rinse water in the washing machine to effectively soften laundry. Alternatively, such emulsions or powder products including such fabric softener can be added to the wash water, with a detergent composition, or the detergent composition can include a fabric softening component, to make a so-called “softergent”. Articles that contain fabric softening component, such as a quaternary ammonium salt, may be added to the automatic laundry dryer, wherein during tumbling of the laundry in a heated environment, the fabric softener is applied to the laundry by repeated contact, and softens it.
Although various fabric softening (and antistatic) compositions have been commercially marketed over the years, with varying degrees of commercial success, and although various fabric softening components thereof have been included in them the most successful of such components have been the quaternary ammonium salts. Such compounds are of the formula
wherein R, R′, R″ and R′″ are all alkyl groups, with at least one of such alkyls being a higher alkyl and with the others being lower alkyl(s) of 1 or 2 carbon atoms, and with X

being a salt-forming anion. Preferably, such quaternary ammonium salt is a di-lower alkyl, di-higher alkyl ammonium halide but mono-lower alkyl tri-higher alkyl ammonium halides have also found use in some instances.
While such quaternary ammonium salts have been effective fabric softeners in the described applications they are however characterized by certain disadvantageous properties, which have led to attempts to find replacements for them. For example, being cationic, they tend to react with anionic materials, sometimes to the detriment of their intended fabric softening function. Moreover, they are not as readily biodegradable as is desirable and they have been reported to be toxic to aquatic organisms, which could lead to harmful effects on aquatic life in lakes, rivers and other waters into which waste waters carrying such compounds could be emptied. Consequently, in many countries regulations have been promulgated restricting the use of quaternary ammonium compounds in products that are ultimately discharged into sewage and drainage systems.
In an effort to find replacements for quaternary ammonium salts as fabric softeners, the prior art has described fabric softening products based on pentaerythritol compounds, such as pentaerythritol esters used alone or in combination with a clay carrier. Such products are said to soften laundry without manifesting the environmental drawback associated with the use of quaternary ammonium compounds as softener, namely its alleged toxicity to aquatic organisms.
U.S. Pat. Nos. 5,126,060; 5,332,513; 5,358,647, and 5,290,459, all assigned to Colgate-Palmolive Company, describe various fabric softening products based on pentaerythritol esters, such products including agglomerated granules, aqueous emulsions and compositions and articles wherein such pentaerythritol esters are used alone or in combination with a clay carrier such as a sodium or calcium bentonite. While the aforementioned disclosures in the prior art have described the benefits of utilizing pentaerythritol esters as the primary fabric softening ingredient in a softening composition or article, there nevertheless remains a need to improve the overall softening performance of such compositions and articles in order to enhance their commercial appeal as effective alternatives to products based on quaternary ammonium salts.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a biodegradable fabric softening composition or article for application to laundry so that a fabric softening portion thereof is deposited on the laundry and softens it, which fabric softening composition or article comprises:
(a) from about 75% to 99%, by weight, of a particulate clay carrier;
(b) from about 0.1% to about 25%, by weight, of a polyphosphonate compound characterized by containing at least two moieties having the structure
—CH
2
—PO(OX)
2
 wherein X is Na or K, at least a portion of said polyphosphonate compound being electrostatically bound to the surface of said clay carrier; and
(c) from about 1% to about 25%, by weight, of a PEC which is a fabric softening compound selected from the group consisting of a higher aliphatic C
12
-C
22
ester of pentaerythritol, an oligomer of pentaerythritol, a C
2
-C
3
alkylene oxide derivative of pentaerythritol or a C
2
-C
3
alkylene oxide derivative of an oligomer of pentaerythritol, and mixtures thereof, at least a portion of said PEC being adsorbed on the surface of said clay carrier, whereby the interaction of said PEC with components (a) and (b) forms a fabric softening composition or article capable of providing a significantly enhanced softening benefit as compared to the softening benefit provided by an otherwise identical softening composition or article containing said PEC in combination with said clay carrier but in the absence of said polyphosphonate compound, and wherein said composition or article is essentially free of a quaternary ammonium compound fabric softener.
In accordance with the process of preparation aspect of the invention there is provided a process for preparing a biodegradable fabric softening composition comprising a particulate clay carrier in combination with a fabric softening amount of a pentaerythritol compound (PEC) and in the absence of a quaternary ammonium compound fabric softener comprising:
(a) heating said particulate clay carrier to a temperature of at least about 80° C.;
(b) contacting the heated clay particles of (a) with a polyphosphonate compound characterized by containing at least two moieties having the structure —CH
2
—PO(OX)
2
wherein X is Na or K, such that at least a portion of said polyphosphonate compound is electrostatically bound to the clay particles;
(c) heating said PEC which is a compound selected from the group consisting of a higher aliphatic C
12
-C
22
ester of pentaerythritol, an oligomer of pentaerythritol, a C
2
-C
3
alkylene oxide derivative of pentaerythritol or a C
2
-C
3
alkylene oxide derivative of an oligomer of pentaerythritol, and mixtures thereof, to a temperature above about its melting point; and then
(d) contacting the molten PEC of (c) with the clay particles of (b) such that at least a portion of said molten PEC is adsorbed on the surface of said clay particles to provide a fabric softening composition capable of providing an enhanced softening benefit.
Also, within the present invention is a process for softening fabrics during laundering comprising contacting such fabrics with an effective amount of a fabric softening composition or article during the washing, rinsing and/or drying operation wherein said fabric softening composition comprises:
(a) from ab

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