Laundry treatment for fabrics

Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Specific organic component

Reexamination Certificate

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Details

C510S470000, C510S513000, C510S515000

Reexamination Certificate

active

06455489

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method of reducing wrinkle formation in a laundry process.
BACKGROUND OF THE INVENTION
Wrinkles or creases in textile fabrics are caused by bending and folding of textiles, which place textiles under a mixture of tension and compression forces. Particularly with cellulosic materials, hydrogen boning between cellulose fibres contributes to keeping these wrinkles in place. The resistance of fabrics against wrinkling depends, amongst other things, on the yarn and fibre bending resistance and the recovery once the force has been released.
Wrinkles or creases in textile fabrics give fabrics an unwanted appearance. Many people do not like the labour involved in removing these unwanted wrinkles.
Easy iron or non-iron garments can be obtained by finishing the garments with poly functional internal cross-linkers such as dimethyolol dihydroxy ethylene urea (DMDHEU) which react inside the fibre with cellulose to form more resilient fibres and yarns. However, cross-linkers such as DMDHEU carry the risk of formaldehyde release. An alternative formaldehyde-free cross-linker is butyl-1,2,3,4-tetracarboxylic acid. A disadvantage of all the aforementioned cross-linkers is that a curing step is needed for the cross-linking reaction, making this method less suitable for a laundry process.
Adhesive polymers are also claimed to provide a wrinkle benefit (e.g. WO 9955814 and WO 9955951, in the name of Procter & Gamble). However, the delivery of these materials onto textiles is not optimal under wash conditions.
The inventors have sought methods of reducing wrinkle formation during laundry processes and providing laundered fabrics with improved ironability.
The present inventors have discovered that certain fabric rebuild materials which undergo a chemical change during a laundry process to increase their affinity for fabric surprisingly reduce the formation of wrinkles during a laundry process. It is also found that wrinkles that are formed can be removed with less effort, leading to improved ironability.
The fabric rebuild agents used are themselves the subject of our patent co-pending application WO 00/18860. This patent application describes a wide general class of fabric rebuild agents which can rebuild fabric during a laundry operation. The present inventors have discovered that a relatively small class of the rebuild agents described in the patent application will provide a surprisingly good anti-wrinkle benefit.
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.
WO 99/14295 is addressed to improving the overall appearance of fabrics during the wash. In particular, it relates to methods of reducing the formation of lint, fuzz or pills and dye loss. There is no reference to wrinkle reduction.
DEFINITION OF THE INVENTION
Thus the present invention provides a method of reducing wrinkle formation in a laundry process, comprising using a laundry treatment composition comprising a water-soluble or water-dispersible rebuild agent for deposition onto a fabric during the laundry process wherein the rebuild agent undergoes during the laundry process, a chemical change by which change the affinity of the rebuild agent for the fabric is increased, wherein the chemical change occurs in or to acetate groups covalently bonded to be pendant on a polymeric backbone 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.
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.
The present invention further provides the use of a fabric rebuild agent which comprises a polymeric backbone, comprising cellulose units or other &bgr;-1,4 linked polysaccharide units, with acetate groups covalently bonded to the polymeric backbone, the average degree of substitution of the acetate groups pendant on the saccharide rings of the backbone being 0.55-0.70, to reduce wrinkle formation in a laundry process.
The exact mechanism by which any of these rebuild agents exert their effect is not fully understood.
Without being bound by any particular theory or explanation, the inventors have conjectured that the mechanism of deposition is as follows.
Cellulose is substantially insoluble in water. Attachment of the acetate groups causes disruption of the hydrogen bonding between rings of the cellulose chain, thus increasing water solubility or dispersibility. In the treatment liquor, it is believed that the acetate groups are hydrolysed, causing the affinity for the fabric to increase and the polymer to be deposited on the fabric. It is believed that the deposited cellulose polymer reinforces the textile fibres and increases their resistance to wrinkling. Further, it is believed that the deposited polymer layer can act as an excellent ironing aid. Accordingly, less iron drag is obtained.
The fabric rebuild polymer used in the present invention does not adversely interact with surfactants and can be absorbed and/or deposited from the wash in an effective manner.
DETAILED DESCRIPTION OF THE INVENTION
The Rebuild Agent
The rebuild agent material used in the present invention is water-soluble or water-dispersible in nature.
The weight average molecu

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