Background and Prior art There have been several prior art documents which describe granular detergent compositions and many such products are commercially available. There are also many such documents that describe use of non-ionic detergents. However, most of the commercially available commercial detergent compositions comprise largely the surfactants of the anionic type. This is due to the easy availability and low cost of these types of surfactants. While these surfactants have good cleaning ability, they perform poorly when washing fabrics in hard water conditions. This inefficiency is compensated by a combination of using higher amounts of surfactants and by use of high amounts of detergent builders. However, the question of the effective utilization of the anionic surfactants is still hotly debated.

Non-ionic surfactants are known to perform better when fabrics are washed using them in hard water. There have been several documents which describe granular detergent compositions comprising non-ionic detergents.

US 5518649 (Unilever, 1996) describes a free flowing detergent composition comprising (i) 10 to 100% (anhydrous basis) of zeolite MAP and (ii) a liquid, viscous-liquid, oily or waxy detergent ingredient for example, a non-ioninc surfactant wherein the ratio of (ii) to (i) being at least 0.01 to 1.

US5789367 (Unilever, 1998) describes laundry detergent compositions comprising (a) 2 to 50% of one or more of any surfactant (b) 5 to 80% of a builder system comprising alkali metal aluminosilicate and (c) a soil release effective

amount of a water soluble or water dispersible soil release polymer characterized in that the component (b) is zeolite MAP and component (c) comprises a non-end capped sulphonated polyester.

US4347152 (Colgate, 1982) describes a free flowing, phosphate free, particulate, heavy duty laundry detergent with a high bulk density having particles of sodium carbonate and sodium bicarbonate having a normally liquid or pasty nonionic detergent in the interiors and on the surface of such particles and coated with ion exchange zeolite particles.

While the above prior arts describe laundry detergent compositions comprising non-ionic surfactants and builders like sodium carbonate, sodium bicarbonate and various zeolites, it does not teach that use of a non-ionic system comprising two selected non-ionic surfactants in specific ratio along with builders provides for superior cleaning while enabling the manufacture of such compositions at low cost.

The present inventors have now found that a detergent composition comprising a non-ionic surfactant system comprising a C8 to C20 primary or secondary alcohol ethoxylates with an average of 9 moles of ethylene oxide and a C8 to C20 primary or secondary alcohol ethoxylates with an average of 3 moles of ethylene oxide in specified ratios along with detergent builder compounds provide for synergistic cleaning benefits. The compositions of the invention ensure enhanced utilization of the components used thereby ensuring low cost.

Objects of the invention It is thus an object of the present invention to provide for a granular detergent composition which provides for superior cleaning efficiency.

It is another object of the present invention to provide for a granular detergent composition that can be prepared at low cost.

It is yet another object of the present invention to provide for a granular detergent composition that can be manufactured with existing equipments of the prior art with minimal modifications thereby ensuring high process efficiencies.

Summary of the Invention : According to one aspect of the invention, there is provided a granular detergent composition comprising (i) 5 to 30% of non-ionic surfactant system and (ii) 20 to 95% builder wherein the non-ionic surfactant system comprises (A) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 9 moles of ethylene oxide and (B) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 3 moles of ethylene oxide such that the ratio of A: B is the range of 9: 1 to 1: 9.

According to another aspect of the invention, there is provided a process for the preparation of a granular detergent composition comprising (i) 5 to 30% of non-ionic surfactant system and (ii) 20 to 95% builder wherein the non-ionic surfactant system comprises (A) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 9 moles of ethylene oxide and (B) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 3 moles of ethylene oxide such that the ratio of A: B is the range of 9: 1 to 1: 9 which process comprises the steps of (i) adding the non-ionic surfactant system to a part of the powders in a high shear mixer to granulate the mix followed by

(ii) layering a part of the powders on to the granules.

It is particularly preferred that the granular detergent composition is used in hand washing of fabrics.

Detailed description of the invention: The present invention provides for a detergent composition comprising builder and a non-ionic surfactant system.

Non-ionic surfactant system : The non-ionic system comprises at least two non-ionic surfactants (A) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 9 moles of ethylene oxide and (B) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 3 moles of ethylene oxide. The surfactants A and B are present in amounts in the ratio of A : B in the range of 9: 1 to 1: 9, more preferably in the ratio in the range of 9: 1 to 1: 3 and further more preferably in the range of 9: 1 to 1: 2.

The non-ionic surfactant system is present in an amount of 5 to 30%, more preferably in the range of 8 to 25%, most preferably in the range of 10 to 20% by weight of the composition.

Builder : The composition according to the invention comprises one or more builders in an amount of 20 to 95%, preferably in an amount of 20 to 70%, more preferably in an amount of 20 to 55% by weight of the composition. The builders are preferably selected from one or more of sodium carbonate, Zeolite 4A, sodium silicate and sodium tripolyphosphate. When sodium carbonate is used, it is preferred that it is dense soda ash. Soda ash is preferably used in an amount of 20 to 60%, more

preferably in an amount of 22 to 55% and most preferably in an amount of 25 to 50% by weight of the composition.

When zeolite 4A is used as a builder, it is preferred that it is used in an amount of 2 to 30%, more preferably in an amount of 5 to 25% and most preferably in an amount of 10 to 20% by weight of the composition.

When sodium silicate is used, it is preferred that it is alkaline sodium silicate. It is preferably used in an amount of 0.5 to 5%, more preferably in an amount of 1 to 3% by weight of the composition.

When sodium tripolyphosphate is used, it is preferred that it is used in an amount of 0.5 to 5% by weight of the composition.

Other Optional ingredients : The granular detergent composition of the invention may additionally comprise fillers like salt. The preferred salts are sodium chloride and sodium sulphate, the most preferred being sodium sulphate. The filler salts may be present in an amount of 0.5 to 15% by weight of the composition.

Beaches may be additionally used in the composition of the invention and the most preferred bleach is sodium sulphite. This may be used in the composition in an amount in the range of 0.5 to 5% by weight of the composition.

Other optional ingredients that may be used in the composition to provide improved user properties include anti-redeposition agents, fluorescers or whitening agents, enzymes, and free flow agents. The preferred free flow agents may be chosen from silica, zeolites, magnesium carbonate or calcite. The most preferred free flow agents are silica and zeolite. The free flow agent is preferably

present in an amount in the range of 0.5 to 15% by weight of the composition.

The preferred anti-redeposition agent may be chosen from sodium carboxymethyl cellulose, polyacrylates, or copolymers of polyacrylic acid and maleic acid. The anti-redeposition agent is preferably present in an amount in the range of 0.2 to 5% by weight of the composition.

While the granular detergent composition of the invention may be used for hand washing or machine washing of fabrics, it is preferred that the composition is used for hand washing of fabrics.

While the composition of the invention may comprise other types of surfactants e. g anionic, cationic, amphoteric or zwitterionic surfactant, it is preferred that any other surfactant, if present, is present in small amounts, preferably not more than 5% by weight of the composition. It is particularly preferred that the composition does not comprise any other type of surfactant especially anionic surfactants in addition to the non-ionic surfactant system.

It is preferred that the composition of the invention has a bulk density higher than 600 grams/liter.

According to another aspect of the present invention there is provided a process for the preparation of a granular detergent composition comprising 5 to 30% of non-ionic surfactant system and 20 to 95% builder wherein the non-ionic surfactant system comprises (A) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 9 moles of ethylene oxide and (B) a C8 to C20 primary or secondary alcohol ethoxylates with an average of 3 moles of ethylene oxide such that the ratio of A: B is the range of 9: 1 to 1: 9 which process comprises the steps of (i) adding the non-ionic surfactant system to a part of the powders in a high shear mixer to granulate the mix followed by

(ii) layering a part of the powders on to the granules.

The process may be carried out in a high-speed mixer/granulator having both a stirring action and a cutting action both of which can be independently controlled both for on-off action and for speed. Suitable types of high shear mixers include the plough share mixers, the Fukae mixer and Lodige mixer.

Alternately, the process to prepare the granular detergent composition of the invention may comprise the steps of (i) mixing the powders with the non-ionic system followed by (ii) drying the mixture in spray dryer.

The invention will now be illustrated with the help of the following non-limiting examples: EXAMPLES Compositions as given in Table-1 were prepared as per the process described below.

The solid powders like soda ash, citric acid, sodium sulphate, sodium carboxymethyl cellulose (SCMC), and about 65% of the total amount of silica were taken in a plough share mixer. Liquid non-ionic surfactant was then sprayed directly into the mixer for about 0.5 to 3 minutes with the mixer blades rotating at about 200 rpm. The alkaline silicate was then added and mixed for a further 0.5 to 3 minutes. The rest of the silica was then added with mixing followed by dosing of perfume and enzymes.

Table-1 Components Comparative Comparative Example-1 Example-2 Example-A Example-B EO3 22 11 4. 4 EO9 22 11 17. 6 Soda Ash 38 38 38 38 SCMC 2. 5 2. 5 2. 5 2. 5 Silica 8 8 8 8 Alkaline silicate 2 2 2 2 Citric acid 5 5 5 5 Sodium To 100 To 100 To 100 To 100 sulphate

EO3 refers to a primary alcohol with 12-14 carbon atoms ethoxylated with an average of 3 moles of ethylene oxide E09 refers to a primary alcohol with 12-14 carbon atoms ethoxylated with an average of 9 moles of ethylene oxide The compositions were used to wash fabrics using the following procedure: The washing was conducted using a test monitor WFK20 obtained from WFK Inc.

Germany. The liquor to cloth ratio was maintained at 100: 1 and the test monitor was washed in hard water in which 3 grams per litre of the composition was dissolved. The test monitor was soaked for 30 minutes before washing in a tergotometer at 100 rpm at 30 °C temperature. The sample was then air dried and the reflectance (R) of the fabric before and after the wash was measured using a Gretag Macbeth Reflectometer from Macbeth Inc. The percentage detergency was calculated using the following formula: (K/S) = (1 00-R) 2/200 R % detergency = [ (K/S) sample- (K/S) soiled]/ [ (K/S) initiai- (K/S) soiied] * 100 The results of the percentage detergency are given in Table-2.

Table-2 Components Comparative Comparative Example-1 Example-2 Example-A Example-B E09 : EO3 ratio 0: 1 1 : 0 1 : 1 4 : 1 % detergency 48. 2 69. 6 77. 9 75. 9

Data in Table-1 indicates that there is synergistic improvement in washing efficiency when the specific mix of surfactants are used in the specified ratios.

EXAMPLES 3 TO 6 Compositions as per Table-3 were prepared using a process as described above along with the data on detergency determined as per the procedure described earlier.

Components Example-3 Example-4 Example-5 Example-6 Total E09 and EO3 14 16 18 20 Ratio of 4: 1 4: 1 4: 1 4: 1 E09 : E03 Soda Ash 35 35 35 35 Zeolite 15 151 15 15 Alkaline silicate 2 2 2 2 Silica 6. 5 6. 5 6. 5 6. 5 Polyacrylate 1 1 1 Sodium sulphate To 100 To 100 To 100 To 100 % Detergency 67. 6 66. 4 69. 3 69. 2

Comparative Example-C A similar fabric was washed with one of the best commercially available formulation (Surf Excel) using the same wash procedure and the percentage detergency was found to be 64.1. In addition to providing improved cleaning, the cost of the compositions of the present invention (Examples 3 to 6) are lower (more than 8% lower) than the commercially available Surf Excel compositions.