Bleaching and dyeing; fluid treatment and chemical modification – Cleaning or laundering
Reexamination Certificate
2001-03-29
2003-02-11
Gupta, Yogendra N. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Cleaning or laundering
C510S276000, C510S357000, C510S360000, C510S421000, C510S426000, C510S470000
Reexamination Certificate
active
06517588
ABSTRACT:
TECHNICAL FIELD
The present invention relates to laundry treatment compositions for laundry cleaning or treatment products, comprising an ingredient for deposition onto fabric during a washing, rinsing or other treatment process.
BACKGROUND OF THE INVENTION
Repeated washing of garments, particularly those comprising cotton or other cellulosic fibres, causes gradual loss of material from individual fibres and the loss of whole fibres from the fabric. These processes of attrition result in thinning of the fabric, eventually rendering it semi-transparent, more prone to accidental tearing and generally detracting from its original appearance.
Hitherto, there has been no way of minimising this kind of damage except by employing less frequent washing and use of less harsh detergent products and/or wash conditions, which obviously tends to less effective cleaning.
In laundry cleaning or treatment products, it is essential for some ingredients to be deposited onto and adhere to the fabric for them to deliver their beneficial effects. Typical examples are fabric conditioners or softeners. Nevertheless, the benefits conferred by such conventional materials do not include rebuilding the fabric.
It has been found possible to include in laundry products, agents which deposit cellulose or cellulose-like materials onto the fabric to at least partially replace the lost material of the fibre.
WO-A-99/14245 discloses laundry detergent compositions containing cellulosic based polymers to provide appearance and integrity benefits to fabrics. These polymers are cellulosic polymers in which the saccharide rings have pendant oxygen atoms to which substituents ‘R’ are bonded, i.e. they are attached to the rings via an ether linkage. The groups ‘R’ can be hydrogen, lower alkyl or alkylene linkages terminated by carboxylic acid, ester or amide groups. Optionally, up to five alkyleneoxy groups may be interspersed between the groups are the respective oxygen atom. At least some of these groups may undergo a chemical change such as hydrolysis, in the wash liquor. However no such change would result in an increased affinity for the fabric. On the contrary, because the “ester” group is configured with the carbonyl group closer to the polysaccharide than the oxygen atom (i.e. esters of carboxyalkyl groups), any hydrolysis will result in free acid substituents which will actually result in an increase in solubility and therefore, a decrease in affinity for the fabric.
WO-A-99/14295 discloses structures analogous to those described in WO-A-99/14245 but in one alternative, the substituents ‘R’ together with the oxygen on the saccharide ring, constitute pendant half-esters of certain dicarboxylic acids. A single example of such a material is given. The dicarboxylic acid half-esters would tend to hydrolyse in the wash liquor and thereby increase affinity of the material for a cotton fabric. However, first, this mechanism of action or behaviour is not mentioned. Second, the hydrolysis rate of such dicarboxylic acids half esters is not as great as that of esters of monocarboxylic acids (which are not disclosed or claimed in WO-A-99/14295). Third, the degree of substitution for this variant is specified as being from 0.001 to 0.1. This is so low as to make the enhancement of fabric affinity too low to be worthwhile for this mechanism of action. Fourth, the structures described and claimed insofar as they have such half ester substituents, must also have substituents of the type which are carboxyalkyl groups or esters thereof, i.e. of the type also described in WO-A-99/14245. In the latter (ester) case, these would hydrolyse to the free acid form. The degree of substitution of the latter (0.2 to 2) is considerably higher than for the half-ester groups and the resultant increase in solubility would easily negate any enhanced affinity for the fabric by hydrolysis of the half-ester groups.
Our copending patent application no. WO 00/18860 discloses compositions comprising a water soluble or water dispersible rebuild agent for deposition onto fabric during a treatment process, wherein the rebuild agent undergoes during the treatment process, a chemical change by which the affinity of the rebuild agent for the fabric is increased. According to one aspect, the chemical change occurs in groups covalently bonded to be pendant to the polymeric backbone of the rebuild agent via an ester linkage, the ester-linked groups being selected from monocarboxylic acid esters. In a second aspect, the backbone comprises cellulose units or other &bgr;-1,4 linked polysaccharide units, the average degree of substitution of the total of all groups pendant on the saccharide rings of the backbone being from 0.3 to 3.0. A preferred fabric rebuild agent is “cellulose monoacetate” which is used to denote acetates with a degree of substitution of 1 or less.
Detergent compositions containing the rebuild agents are stated to give pH of the wash liquor from 7 to 10.5 for a main wash detergent. Many of the examples of the disclosure employ cellulose monoacetate with a degree of substitution of acetate groups of 0.48 or 0.50.
The present inventors have now discovered that cellulose monoacetate of a given narrow range of degree of substitution and molecular weight, when used in a detergent composition which gives a wash liquor of pH in the range 9.5 to 11.0 more preferably 10 to 11 gives particularly improved deposition.
DEFINITION OF THE INVENTION
A laundry treatment composition comprising a water-soluble or water-dispersible rebuild agent for deposition onto a fabric during a treatment process wherein the rebuild agent undergoes during the treatment process, a chemical change by which change the affinity of the rebuild agent for the fabric is increased, said chemical change occurring in or to acetate groups covalently bonded to be pendant on a polymeric bakcbone of the rebuild agent and which backbone comprises cellulose units or other &bgr;-1,4 linked polysaccharide units, the average degree of substitution of the acetate groups pendant on the saccharide rings of the backbone being from 0.55 to 0.70, the weight average molecular weight of the rebuild agent being in the range 12,000 to 20,000, the pH of an aqueous solution of the laundry treatment composition at 20° C. at a concentration of 1 g of composition per litre of water being in the range 9.5 to 11.0, provided that the laundry treatment composition does not comprise cellulose acetate of average molecular weight 10,000, which comprises acetate groups covalently bonded to the cellulose backbone, with a degree of substitution of 0.58 or 0.65, the disclaimed composition comprising linear alkyl benzene sulphonate and a nonionic surfactant comprising a C
13
-C
15
alcohol ethoxylated with 7 moles of ethylene oxide per mole of alcohol, the weight ratio of anionic surfactant to said ethoxylated alcohol nonionic surfactant of the disclaimed composition being 1:1.
Throughout this specification, “average degree of substitution” refers to the number of substituted pendant groups per saccharide ring, averaged over all saccharide rings of the rebuild agent. Each saccharide ring prior to substitution has three —OH groups and therefore, an average degree of substitution of 3 means that each of these groups on all molecules of the sample, bears a substituent.
According to a second aspect, the present invention provides a method of rebuilding a fabric to replace fibre loss due to washing, the process comprising treating the fabric with a composition according to the present invention.
The exact mechanism by which the rebuild agents exert their effect is not fully understood. Whether or not they can repair thinned or damaged fibres is not known. However, they are capable of replacing lost fibre weight with deposited and/or bonded material, usually of cellulosic type. This can provide one or more advantages such as repair or rebuilding of the fabric, strengthening of the textile or giving it enhanced body or smoothness, reducing its transparency, reducing fading of colours, improving the appearance of the fabric o
Bornstein Alan A.
Unilever Home & Personal Care, USA , a divsion of Conopco
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