Use of a crystal growth inhibitor to reduce fabric abrasion

Details Use of a crystal growth inhibitor to reduce fabric abrasion Use of a crystal growth inhibitor to reduce fabric abrasion

2000-06-19

2004-02-17

Gupta, Yogendra N. (Department: 1751)

Bleaching and dyeing; fluid treatment and chemical modification

Chemical modification of textiles or fibers or products thereof

With coating, sizing, or lubricating

C008S115510, C510S461000, C510S508000

Reexamination Certificate

active

06692536

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to the use of a crystal growth inhibitor for reducing the abrasion of fabrics arising upon laundering treatment.
BACKGROUND OF THE INVENTION
The appearance of fabrics, e.g., clothing, bedding, household fabrics such as table linens is one of the areas of concern for consumers. Indeed, upon typical consumer's uses of the fabrics such as wearing, washing, rinsing and/or tumble-drying of fabrics, a loss in the fabric appearance can take place. It has now been found that this loss is at least partly due to abrasion of the fabrics fibers upon laundering treatments. Such a problem of fabric abrasion is even more acute after multiwash cycles.
The solving of this problem has been achieved in the art by at least two ways either (i) remedying the fabric abrasion which has already occurred or by (ii) preventing the problem of fabric abrasion.
One solution for solving this problem by means of (i) is given in U.S. Pat. No. 3,894,318 whereby the fabric abrasion problem, which in turn results in a pilling effect on the fabric, is reduced by further abrading the fabric.
On the other hand, one solution for solving this problem by means of (ii) is by treating the fabric with polymeric substances which will deposit onto the fabric and and thus protect the fibers from abrasion. Typical disclosure can be found in U.S. Pat. No. 4,985,040 which provides firstly the deposition of a polyamide-epichlorhydrin resin and then that of a polyurethane.
Notwithstanding the advances in the art represented by the above disclosure, there is still a need for solutions that will provide efficient fabric abrasion reduction.
It has now been found that the use of a crystal growth inhibitor (CGI), in particular a limescale CGI, fulfills such a need.
By “efficient fabric abrasion reduction”, it is meant that fabrics treated with the CGI exhibit an improved appearance due to a reduced fabric abrasion compared to untreated laundered fabrics.
Crystal growth inhibitors, in particular of the organic diphosphonic type have long been known in the art of detergent to reduce limescale build up to washing machine parts (e.g. heating resistance). A typical disclosure can be found in WO 97/05226 wherein the CGI ameliorates the white deposits problem caused by carbonate salts. Their use as a fabric abrasion reduction agent is not disclosed.
By “crystal growth inhibitor”, it is meant a compound that reduces the rate of formation of inorganic microcrystals, thereby reducing the size and/or the amount of such micro-crystals at the fabric surface.
It is therefore an advantage of the invention to provide the use of a crystal growth inhibitor for reducing fabric abrasion, in particular fabric abrasion which occur upon domestic laundering process.
SUMMARY OF THE INVENTION
The present invention relates to the use of a crystal growth inhibitor for reducing fabric abrasion, in particular fabric abrasion which arises upon the domestic laundering process of fabrics.
DETAILED DESCRIPTION OF THE INVENTION
Crystal Growth Inhibitor
A crystal growth inhibitor is the essential component of the invention.
The suitable CGI for use herein can be defined by the following test procedure, so called crystal growth inhibition test measurement.
Crystal Growth Inhibition Test Measurement
The ability for a compound to inhibit crystal growth can be assessed by evaluating the impact in vitro on the growth rate of inorganic micro-crystals. For this purpose, a system developed by G. H. Nancollas in 1964, described in Nancollas, G. H and Koutsoukos, P. G. “Calcium Phosphate Nucleation and Growth in solution.”
Prog. Crystal Growth Charact.
3, 77-102 (1980) can be used. This system consists of measuring the growth rate of calcium phosphate crystals seeded with hydroxyapatite ([Ca
5
(PO
4
)
3
OH] or HAP) in the presence of CaCl
2
and NaH
2
PO
4
. Calcium phosphate growth liberates protons that can be titrated with a strong base. The amount of base needed to keep the pH constant over the crystal growth enables persons skilled in the art to measure the crystal growth rate directly as well as to determine the effects of potential crystal growth rate inhibitors. A typical plot of such an experiment is given in FIG.
1
.
The observed t-lag value defines the efficiency of a compound to inhibit the growth of calcium phosphate crystals; wherein the higher the t-lag, the better the CGI.
The following procedure can be used to build the plot given experimentally in FIG.
1
.
Place 350 mL of distilled water (distilled twice), 35 mL of KCl 2.1M, 50 mL of CaCl
2
0.0175M and 50 mL of KH
2
PO
4
0.01M in a reaction vessel. Insert a glass pH electrode and a standard calomel reference electrode connected to an auto-titrator. Bubble nitrogen gas and stabilize the temperature of the reaction mixture to 37° C. When temperature and pH are stabilized, add the CGI candidate at the concentration to be tested (e.g. 1.10
−6
M). Titrate to pH 7.4 with KOH 0.05M. Then seed the reaction mixture with 5 mL of hydroxyapatite slurry [Ca
5
(PO
4
)OH].
The hydroxyapatite slurry is prepared as follows:
100 gr of Bio-Gel® HTP hydroxyapatite powder is dispersed in 1 L of distilled water. The pH of the resulting slurry is lowered to 2.5 by dropwise addition of HCl 6N. This is then heated to boiling and refluxed while stirring for seven days in a 2 L round-bottom flask connected to a condenser. After cooling, to room temperature, pH is adjusted to 12.0 by dropwise addition of 50% NaOH and the slurry is refluxed for another seven days as before. The slurry is allowed to settle for two days and the supernatant is suctioned off. The flask is refilled with 1.5 L of distilled water, stirred vigorously, an allowed to settle again for two days. A total of seven rinses as described above are performed. The pH is adjusted to 7.o by dropwise addition of HCl 2N while stirring vigorously. The resulting slurry is stored at 37° C. for eleven months.
The plot shown above is obtained by recording the amount of base added over time to maintain the pH of the reaction medium. T-lag for a particular crystal growth inhibitor is determined graphically as described in the figure above.
The crystal growth inhibitors to be used for the purpose of this invention have a t-lag of at least 10 minutes at a concentration of 1.10
−6
M, preferably at least 20 minutes, most preferably at least 50 minutes.
Still another suitable method for determining the crystal growth inhibition property of the selected component which is comparable to the T-lag method is by a visual grading. The method is as follows: A multicycle laundry test is performed over several (e.g. 10) cycles of repeated washing and tumble drying. The conditions used are representative for the desired geographical region (e.g. domestic washing machine used, detergent used, rinse added product use, water hardness, clothing articles washed etc.). At least two test legs are run in parallel, including the composition of the invention and a separate reference leg. After the required number of washing cycles have been performed the test garments (articles of clothing) are taken for comparison by expert graders under controlled lighting conditions. The visual grading is a better/worse comparison of the visible crystalline residue on the surface of the test garments, comparing the test leg to the reference leg. Dark coloured, knitted cotton articles are most suitable for this comparison.
In addition, the crystal growth inhibitors, differentiate themselves from the chelating agents by their low binding affinity for copper defined by its Log K, i.e. the ML/M.L Log K at 25C., 0.1 ionic strength, of the CGI is of less than 15, preferably less than 12.
Preferably, the CGI for use in the present invention are selected from carboxylic compounds, organic monophosphonic acids, organic diphosphonic acids, and mixtures thereof.
Carboxylic Compounds
Typical of carboxylic compound for use herein are the carboxylic compounds selected from glycolic acid, phytic acid, monomeric polycarboxylic acids, h

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