As a usual part of a cleaning operation, e.g. for kitchenware, an aqueous composition or water is applied to the cleansed articles to remove the detergent composition employed during a previous cleansing step. This is generally referred to as a rinse step. However, this has the disadvantage of re-wetting the items and in many cleaning operations it is desired that the cleansed items dry as quickly as possible. This is especially true in both manual and automatic dishwashing operations where the time taken for cleaned items, such as kitchenware, to dry is very noticeable. In automatic dishwashing, there is a desire for the items to be dry when the dishwashing machine is opened and if this is not achieved it often leads to dissatisfaction with the cleaning operation. With manual dishwashing it is desired that the cleansed items dry as quickly as possible so that wet items do not need to be left for prolonged periods to dry in the open air.
Achieving rapid drying of cleansed items has been found to be a particular problem for plastic ware as the hydrophilic properties of the plastic often leads to prolonged drying times which is recognised as undesirable.
Therefore, there is a need in the art to provide detergent compositions exhibiting good drying properties. In particular there is a need in the art to provide such detergent compositions which provide good drying properties on plastic items. Furthermore there is a need to provide such compositions which exhibit good stability of the ingredients.
It is an object of the present invention to address one or more of the above-mentioned problems. In particular, it is an object of the present invention to provide detergent compositions that provide good drying of cleansed articles and especially on plastic ware. It is a further object of the present invention to provide detergent compositions that provide good drying of cleansed articles, especially plastic ware, that have been subjected to a manual or automatic dishwashing operation. It is a further object to provide such detergent compositions which exhibit good stability and drying properties for cleansed articles.
It has now been found according to the present invention that certain (anionic) polyesters provide good drying properties especially on plastic ware and most especially in dishwashing applications.
Polyesters produced from dicarboxylic acids, such as terephthalic acid, isophthalic acid, sulphonated aromatic dicarboxylic acids, such as sulphoisophthalic acid, and diols, such as alkyleneglycol, and the use thereof as a Soil Release Polymer (SRP) is well known.
U.S. Pat. No. 4,427,557 describes polyesters of molar weight in the range of from 2,000 to 10,000 g/mole, produced from the monomers; 1) ethyleneglycol, 2) polyethyleneglycol of molar weight ranging from 200 to 1,000 g/mole, 3) aromatic dicarboxylic acids and 4) alkali salts of sulphonated aromatic dicarboxylic acids and their soil release effect on polyester fabrics.
U.S. Pat. No. 4,702,857 discloses polyesters of 1) ethyleneglycol, 1,2-propyleneglycol or mixtures thereof, 2) polyethylene glycol with a minimum of 10 glycol units, terminating at one end in a short-chain alkyl group, specifically a methyl group, 3) a dicarboxylic acid or ester and optionally 4) alkali salts of sulphonated aromatic dicarboxylic acids.
U.S. Pat. No. 4,721,580 discloses polyesters with terephalate units and sulphonic terminal groups, specifically sulphoethoxylated terminal groups MO3S(CH2CH2O)n—H, and describes the use thereof in detergents and softening agents.
U.S. Pat. No. 4,968,451 describes polyesters with sulphonic terminal groups, obtained by the copolymerisation of (meth)alyl alcohol, alkylene oxide, aryldicarboxylic acid and C2-C4-glycol, with subsequent sulphonation.
U.S. Pat. No. 5,415,807 describes the tendency of SRPs with sulphonated polyethoxy/propoxy terminal groups to crystallization, thereby reducing their soil release effect and suggests that the tendency of SRPs to crystallise can be reduced by the addition of hydrotropes.
U.S. Pat. No. 5,691,298 discloses SRPs with a branched backbone structure of di- or polyhydroxysulphonate, terephthalate and 1,2-oxyalkyleneoxy units with non-ionic or anionic terminal groups.
WO 02/18474 describes non-ionic oligoesters which display flow properties and the use thereof for the cleaning of hard surfaces. These oligoesters are unsuitable for solid formulations.
WO 01/23515 discloses anionic polyesters and the use thereof for the cleaning of hard surfaces, wherein these polyesters contain terminal groups which incorporate sulphonic groups. These types of polyesters are viscous, and their use in solid applications is problematic.
EP 1 035 194 describes the potential use of comb-shaped polyesters in cleaning agents and detergents.
EP 964 015 and US 2002 042 354 describe polyesters formulated from the monomers terephthalic acid, 5-sulphoisophthalic acid, ethyleneglycol, polyethyleneglycol, propyleneglycol, polypropylene glycol and polyalkyleneglycol monoalkylether, in which the polyalkyleneglycol monoalkylether is formed of more than 6 glycol units. Polyesters of this type are liquids or viscous solids.
WO 99/09125 discloses washing agents and detergents incorporating polyesters which contain acetal groups and which are liquid at room temperature.
Oligomeric soil release agents comprising terephthalate monomer units for use in fabric care compositions are disclosed in WO 95/02030.
U.S. Pat. No. 5,786,318 discloses soil release agents for a laundry detergent, the agents comprising PEG or end capped PEG.
U.S. Pat. No. 5,789,366 and U.S. Pat. No. 6,255,274 discloses a detergent composition comprising a soil-release polyester comprising monomer units of a terephthalic acid.
WO 93/21294 discloses a detergent composition comprising a polyester comprising dimethylterephthalate.
Previously known anionic SRPs with sulphonic groups generally exhibit good water solubility, but also show a tendency to hygroscopicity and viscosity. The direct grinding of the cooled polyester charge by the use of hammer mills, screen mills or “cylinder mills” is generally not possible. The high uptake of water during the milling process leads to fouling by adhesion and the associated breakdown of continuous operation. Even where acceptable results can be achieved by the use of special, energy-intensive processes such as low-temperature milling (cryo-milling) or spray drying from an aqueous solution, the stability of anionic SRP granulates in storage is limited by their capacity for water absorption.
It is a further object of the present invention to provide detergent compositions which comprise polyesters exhibiting good water solubility, good soil release properties, which remain stable (especially to hydrolysis) in the compositions and which do not adversely affect the stability thereof. These polyesters should show effective and spontaneous water solubility at temperatures below 60° C., and their effects in the compositions into which they are incorporated should be obtained even with a relatively low amount of water. They should also be suitable for formulation as stable granulates, without the substantial consumption of energy.