Detergent compositions comprising bleaching agent and brightener

Abstract

 The present invention relates to a granular detergent composition comprising a particulate bleaching agent and a particulate brightening agent, wherein the particulate brightening agent comprises (a) stilbene brightener and (b) biphenyl or bis(benzoxazole) brightener and wherein the ratio of stilbene brightener to biphenyl/benzoxazole brightener is at least 4:1, preferably at least 5:1, and most preferably at least 6:1.

Description

[0001] The present invention relates to granular detergent compositions comprising a particulate bleaching agent and a particulate brightening agent, wherein the particulate brightening agent comprises (a) stilbene brightener and (b) biphenyl or bis(benzoxazole) brightener.

[0002] Brightener decomposition in granular laundry detergents negatively impacts on cleaning performance, and in the worst case, gives an undesirable yellow appearance to the powder upon storage. Stilbene brighteners, whilst being preferred for good product performance, readily degrade if processed and/or subsequently stored in proximity to bleach, certain bleach activators or free moisture.

[0003] Furthermore dry added particulate stilbene brightener has a poor rate of solubility.

[0004] EP-A 364027, published on 18th April, 1990, identifies a problem of stilbene brightener stability in the presence of bleaching agents including percarbonate. Detergent compositions comprising either stilbene and biphenyl brighteners are disclosed in the examples. The problem is addressed by using a brightener which is a specific biphenyl brightener.

[0005] EP-A 577557, published on 5th January 1994, identifies certain hydrated biphenyl brighteners as having good storage stability.

[0006] Hence, biphenyl brighteners are known to be more stable, but they are also more expensive than stilbene brighteners.

[0007] Co-granulated stilbene and biphenyl brighteners are currently commercially available. For example Tinopal-CDX®, supplied by Ciba-Geigy has a stilbene to biphenyl brightener ratio of about 2.2:1.

[0008] However all of these known components and compositions require considerable amounts of the biphenyl brightener which is much more expensive than stilbene brighteners. Hence it is surprising that high ratios of stilbene to biphenyl brightener retain the storage stability and rate of solubility advantages of the biphenyl brightener, yet offer much of the cost benefit of the stilbene brightener.

[0009] It has now been found that stilbene brighteners co-granulated with low levels of biphenyl or bis(benzoxazole) brighteners overcome problems of brightener stability and rate of solubility.

Summary of the Invention

[0010] According to the present invention a granular detergent composition is provided comprising a particulate bleaching agent and a particulate brightening agent, wherein the particulate brightening agent comprises (a) stilbene brightener and (b) biphenyl or bis(benzoxazole) brightener and wherein the ratio of stilbene brightener to biphenyl/benzoxazole brightener is at least 4:1, preferably at least 5:1, and most preferably at least 6:1.

[0011] In preferred embodiments of the invention the stability of the brightener is still further improved by ensuring low moisture levels in the particulate brightening agent itself, and/or in the granular detergent composition as a whole. Preferably the particulate brightening agent comprises less than 5% by weight of water and/or the equilibrium relative humidity (eRH) of the finished composition is less than 5%. In a most preferred embodiment, in which the detergent composition further comprises zeolite, the zeolite is dried to a moisture level of less than 15% by weight, preferably less than 10% by weight, before it is incorporated into the composition.

Detailed Description of the Invention

Particulate Brightening Agent

[0012] The particulate brightening agents of the present invention comprise at least one stilbene brightener and at least one biphenyl or bis(benzoxazole) brightener.

[0013] Suitable stilbene brighteners for use in the present invention are derived from bis(4,4'-triazinylamino)stilbene-2,2'-disulphonic acid, preferably derived from :
Disodium 4,4'-bis[(4-anilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate or
Tetrasodium 4,4'-bis[(4-sulfoanilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate.
(according to the Ullmann's Encyclopedia of Industrial Chemistry, 1991, Vol A 18 page 158-159)
The stilbene brightener is most preferably derived from disodium 4,4'-bis[(4-anilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate where R = morpholino or diethanolamino (also known as Colour Index No 71 and no 28 according to the Society of Dyers and Colorists and the American Association of Textile Chemists and Colorists).

[0014] Suitable biphenyl and benzoxazole brighteners for use in the present invention are derived from distyrylbiphenyl, bis(benzo[b]furan-2-yl)biphenyl and bis(benzoxazole) according to the Ullmann's Encyclopedia of Industrial Chemistry, 1991, Vol A 18 page 157-163) :
Preferred examples include those derived from: Disodium 4,4'-bis (2-sulphostyryl) biphenyl Disodium 4,4-bis (4-chloro-3-sulphostyryl) biphenyl Disodium 4,4'-bis(sulfobenzo[b]furan-2-yl)biphenyl 2,5-bis(benzoxazole-2-yl)thiophene and mixtures thereof
Of these the most preferred is disodium 4,4'-bis (2-sulphostyryl) biphenyl (also known as Colour Index No 351 according according to the Society of Dyers and Colorists and the American Association of Textile Chemists and Colorists).

Particulate Bleaching Agent

[0015] The granular compositions of the present invention further comprise a granular component comprising a bleaching agent chosen from the group comprising alkalimetal percarbonate, peroxyacid, perimidic acid or combinations of these. (This component is described hereinafter as the "bleaching component")
Percarbonate will generally be solid and granular in nature. It may be added to granular detergent compositions without additional protection. However, such granular compositions may utilise a coated form of the material which provides better storage stability for the percarbonate in the granular product.

[0016] The sodium salt of percarbonate is preferred for use in the present invention. Sodium percarbonate is an addition compound having a formula corresponding to 2Na2CO3.3H2O2, and is available commercially as a crystalline solid. Most commercially available material includes a low level of a heavy metal sequestrant such as EDTA, 1-hydroxyethylidene 1,1-diphosphonic acid (HEDP) or an amino-phosphonate, that is incorporated during the manufacturing process. For the purposes of the present invention, the percarbonate may be incorporated into detergent compositions without additional protection, but preferred embodiments of the invention utilise a coated form of the material. Suitable coating materials include the alkali and alkaline earth metal carbonates and sulphates or chlorides. The most preferred coating material comprises a mixed salt of alkali metal sulphate and carbonate. Such coatings together with coating processes have previously been described in GB 1 466 799, granted to Interox on 9th March, 1977. The weight ratio of the mixed salt coating material to percarbonate lies in the range from 1:200 to 1:4, more preferably from 1:100 to 1:10, and most preferably from 1:50 to 1:20. Preferably, the mixed salt is of sodium sulphate and sodium carbonate which has the general formula Na2SO4.n.Na2CO3 wherein n is from 0.1 to 3, preferably n is from 0.3 to 1.0 and most preferably n is from 0.2 to 0.5.

[0017] Another suitable coating material is sodium silicate of SiO2:Na2O ratio from 1.6:1 to 3.4:1, preferably 2.8:1, applied as an aqueous solution to give a level of less than 2% of silicate solids by weight of percarbonate. Magnesium silicate can also be included in the coating.

[0018] Where the bleaching processes utilising the compositions of the invention are carried out at least in part at temperatures lower than about 60°C, the compositions of the invention may contain bleaching agents more suited to low temperature bleaching. These will include, for example, preformed organic peracids and perimidic acids. The following are examples of preformed peroxy acids or perimidic acids which are useful in the present invention:

PAP:

N,N phthaloylaminoperoxy caproic acid

C-PAP:

2-carboxy-phthaloylaminoperoxy caproic acid

PAPV:

N,N phthaloylaminoperoxy valeric acid

NAPAA:

Nonyl amide of peroxy adipic acid

DPDA:

1, 12 diperoxydodecanedioic acid

Peroxybenzoic acid and ring substituted peroxybenzoic acid
Monoperoxyphtalic acid (magnesium salt, hexahydrate) Diperoxybrassylic acid

Detergent Builders and Surfactants

[0019] A highly preferred component of the compositions of the present invention is zeolite. Most preferably some or all of the zeolite used is dried to a moisture level of less than 15% by weight, preferably less than 10% by weight, before it is incorporated into the composition. Suitable zeolites include crystalline aluminosilicate ion exchange material of the formula:

        Na_z[(AlO₂)_z·(SiO₂)_y]·xH₂O

wherein z and y are at least about 6, the molar ratio of z to y is from about 1.0 to about 0.4 and z is from about 10 to about 264. Amorphous hydrated aluminosilicate materials useful herein have the empirical formula

        M_z(zAlO₂·ySiO₂)

wherein M is sodium, potassium, ammonium or substituted ammonium, z is from about 0.5 to about 2 and y is 1, said material having a magnesium ion exchange capacity of at least about 50 milligram equivalents of CaCO₃ hardness per gram of anhydrous aluminosilicate. Hydrated sodium Zeolite A with a particle size of from about 1 to 10 microns is preferred.

[0020] The crystalline aluminosilicate ion exchange materials are further characterized by a particle size diameter of from about 0.1 micron to about 10 microns. Amorphous materials are often smaller, e.g., down to less than about 0.01 micron. Preferred ion exchange materials have a particle size diameter of from about 0.2 micron to about 4 microns. The term "particle size diameter" herein represents the average particle size diameter by weight of a given ion exchange material as determined by conventional analytical techniques such as, for example, microscopic determination utilizing a scanning electron microscope. The crystalline aluminosilicate ion exchange materials herein are usually further characterized by their calcium ion exchange capacity, which is at least about 200 mg equivalent of CaCO₃ water hardness/g of aluminosilicate, calculated on an anhydrous basis, and which generally is in the range of from about 300 mg eq./g to about 352 mg eq./g. The aluminosilicate ion exchange materials herein are still further characterized by their calcium ion exchange rate which is at least about 2 grains Ca⁺⁺/gallon/minute/gram/gallon of aluminosilicate (anhydrous basis), and generally lies within the range of from about 2 grains/gallon/minute/gram/gallon to about 6 grains/gallon/minute/gram/gallon, based on calcium ion hardness. Optimum aluminosilicate for builder purposes exhibit a calcium ion exchange rate of at least about 4 grains/gallon/minute/gram/gallon.

[0021] The amorphous aluminosilicate ion exchange materials usually have a Mg⁺⁺ exchange of at least about 50 mg eq. CaCO₃/g (12 mg Mg⁺⁺/g) and a Mg⁺⁺ exchange rate of at least about 1 grain/gallon/minute/gram/gallon. Amorphous materials do not exhibit an observable diffraction pattern when examined by Cu radiation (1.54 Angstrom Units).

[0022] Aluminosilicate ion exchange materials useful in the practice of this invention are commercially available. The aluminosilicates useful in this invention can be crystalline or amorphous in structure and can be naturally occurring aluminosilicates or synthetically derived. A method for producing aluminosilicate ion exchange materials is discussed in U.S. Pat. No. 3,985,669, Krummel et al., issued Oct. 12, 1976, incorporated herein by reference. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite B, Zeolite M, Zeolite P and Zeolite X. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula

        Na₁₂[(AlO₂)₁₂(SiO2)₁₂]·xH₂O

wherein x is from about 20 to about 30, especially about 27 and has a particle size generally less than about 5 microns.

[0023] Other components such as surfactants, builders and minors are also useful in the compositions of the present invention.

[0024] Surfactants include, but are not limited to C11-C18 alkyl benzene sulphonates ("LAS") and primary, branched-chain and random C10-C20 alkyl sulphates ("AS"), the secondary (2,3) alkyl sulphates, the C10-C18 alkyl alkoxy sulphates ("AExS"; especially EO 1-7 ethoxy sulphates), C10-C18 alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates) the C10-C18 glycerol ethers, the C10-C18 alkyl poyglycosides and their corresponding sulphated polyglycosides, and C12-C18 alpha-sulphonated fatty acid esters. If desired , the conventional nonionic and amphoteric surfactants such as the C12-C18 alkyl ethoxylates ("AE") including the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol alkoxylates, C12-C18 betaines and sulphobetaines ("sultaines"), C10-C18 amine oxides, and the like, can also be included in the overall composition.

[0025] Detergent builders include, but are not limited to, alkali metal, ammonium and alkyanolammonium salts of polyphosphates, (exemplified by the tripolyphosphates, pyrophosphates, and glassy polymeric metaphosphates), phosphonates, phytic acids, silicates (including crystalline layered silicates, carbonates (including bicarbonates and sesquicarbonates), sulphates and aluminosilicates (mentioned above). Also ether hydroxypolycarboxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, polyacetic salts such as ethylenediamine tetraacetic acid and nitrilotriacetic acid, polycarboxylates such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3,5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof, citric acid and soluble salts thereof

[0026] Useful minors include, but are not limited to enzymes, enzyme stabilisers, soil release agents, chelating agents, clay soil / antiredeposition agents, dispersing agents, suds suppressor, fabric softening including smectite clay, dye transfer agents, perfume etc.

Example 1

[0027] A mixture of granular raw materials (% by weight) were prepared according to the following compositions :

Table 1

	Example 1	Comparative Example A
Anionic surfactant agglomerate *	30	30
Layered silicate compacted granule (supplied by Hoechst under trade name SKS-6®)	18	18
Percarbonate (supplied by Interox)**	25	25
TAED agglomerate	9	9
Suds suppressor agglomerate	3.5	3.5
Perfume encapsulate	0.2	0.2
Granular dense soda ash	6.7	6.7
Granular acrylic-maleic copolymer	3.2	3.2
Enzymes	3.6	3.6
Granular soil release polymer	0.6	0.6
Brightener granule (6.7/1 ratio of stilbene/biphenyl) supplied by Ciba Geigy)	0.3	-
Brightener granule (2.2/1 ratio of stilbene/biphenyl) (supplied by Ciba Geigy)	-	0.3
Partially hydrated zeolite A (8% moisture)	8	8
Zeolite A (20 % moisture)	-	8

* Anionic surfactant agglomerates were made from a 78% active surfactant paste which comprises C45AS/C35AE3S in the ratio of 80:20. The paste was agglomerated with a powder mixture according to the process described in EPA510746. The resulting anionic surfactant granule had a composition of 30% C45AS, 7.5% C35AE3S, 24% zeolite, 20% carbonate, 2.5% CMC, 12% acrylic-maleic co-polymer, and the balance of moisture.

** Percarbonate coated with 2.5% carbonate/sulphate with mean particle size of 500 microns.

[0028] The mixture of granular ingredients listed above was placed inside a 140 litre rotating drum that operates at 25 rpm. While operating the drum a mixture of nonionic surfactants (C25E3/polyhydroxy fatty acid amide in a 70/30 ratio) were sprayed onto the granular mixture to a level of 7% by weight of the granular components. The spraying time was about 1-2 minutes. Immediately afterwards, perfume was sprayed on, at a level of 0.5% by weight of the granular components, while rotating the drum. Then, without stopping the rotation of the drum, a flow aid (by 8 % of weight) was slowly added to the mixer, taking about 30 seconds. Once the addition of flow aid was finished, the mixer was allowed to rotate for about 1 minute and was then stopped. The finished product was then removed from the rotating drum. The flow aid used was partially hydrated zeolite A (8 % moisture).

Comparative Example A

[0029] The process of example 1 was repeated using the components listed in table 1. The flow aid used was zeolite A (20 % moisture).

[0030] All products were stored at 35°C/80% eRH cartonboard boxes and plastic refills. The hunter color is measured. When brightener is being degraded the finished product turns yellow, which is reflected in higher b values.

Storage conditions	Example 1	Comparative Example A
start	- 3.8	-3.0

Carton
2 weeks 35°C/80% eRH.	- 3.12	1.38

Refill Bag
2 weeks 35°C/80% eRH.	- 3.07	1.5
The % eRH in the packed product was
start	1.3	32

Carton
2 weeks 35°C/80% eRH.	35	48

Refill Bag
2 weeks 35°C/80% eRH.	20.1	40

Example 2

[0031] The following laundry detergent composition (by % weight) was prepared:

	Example 2	Comparative	Examples
		B	C
Surfactant agglomerate
zeolite MAP	20	20	20
carbonate	10	10	10
C24AS	10	10	10
(Alkyl sulfate)
C24E3 alcohol	10	10	10
ethoxylate
moisture	5	5	5
Brightener (2.2/1 ratio of stilbene/biphenyl)	-	0.2	0.2

Dry mixing
Percarbonate*	18	18	18
TAED	5	5	5
Bleach Cata-lyst (ppm)	100	100	100
Sodium carbonate	5	5	5
Sodium Silicate 2R	5	5	5
Chelant	0.5	0.5	0.5
Enzyme	3	3	3
Antifoam	3	3	3
Brightener granule (6.7/1 ratio of stilbene/biphenyl)	0.2	-	-

Spray-on
Perfume	0.3	0.3	0.3

Coating
Zeolite A (20 % moisture)	-	5	-
Zeolite A (8% moisture)	5	-	5

* coated with 3% borosilicate, mean particle size 600 microns

[0032] All products were stored at 35°C/80% eRH and 50°C in cartonboard boxes and plastic refills. The hunter color is measured. When brightener is being degraded the finished product turns yellow, which is reflected in higher b values.

	Storage conditions 2	Example B	Comparative Examples C
start	3.9	4	4.5

Carton
2 weeks 35°C/80% eRH.	5.9	11	9.5
2 weeks at 50°C	5.6	19.7	16.5

Refill Bag
2 weeks 35°C/80% eRH.	6.2	9.3	8.9
2 weeks at 50 °C	7.5	13.5	12.9
The brightener concentration is measured (ppm):

	Storage conditions 2	Example B	Comparative Examples C
start	950	940	950

Carton
2 weeks 35°C/80% eRH.	825	409	650
2 weeks at 50°C	846	622	656

Refill Bag
2 weeks 35°C/80% eRH.	870	439	622
2 weeks at 50 °C	882	337	464

Example 3

[0033] The following laundry detergent composition (by % weight) was prepared:

	Example 3	Comparative Example D
Extrudate
LAS	10	10
C24E5 alcohol ethoxylate	5	5
Zeolite A	25	30
Carbonate	15	15
Monohydrate Perborate	15	15
Brightener (2.2/1 ratio of stilbene/biphenyl)	-	0.2
Chelant	0.5	0.5
Moisture	5	5

Dry mixing
TAED	5	5
Enzyme	3	3
Antifoam	3	3
Brightener (6.7/1 ratio of stilbene/ biphenyl)	0.2	-
Zeolite A (8 % moisture)	5	-
Balance with minors to 100%

[0034] All products were stored at 35°C/80% eRH in cartonboard boxes and plastic refills. The hunter color is measured. When brightener is being degraded the finished product turns yellow, which is reflected in higher b values.

Storage conditions	Example 3	Comparative Examples D
start	3.5	3.7

Carton
2 weeks 35°C/80% eRH.	3.7	8.7

Refill Bag
2 weeks 35°C/80% eRH.	3.9	7.7

Claims

1. A granular detergent composition comprising a particulate bleaching agent and a particulate brightening agent, wherein the particulate brightening agent comprises (a) stilbene brightener and (b) biphenyl or
bis(benzoxazole) brightener
characterised in that the ratio of stilbene brightener to biphenyl/benzoxazole brightener is at least 4:1.

2. A granular detergent composition according to claim 1, wherein the particulate brightening agent comprises less than 5% by weight of water.

3. A granular detergent composition according to claim 2, wherein the equilibrium relative humidity (eRH) of the composition is less than 5%.

4. A granular laundry detergent composition according to claim 1 further comprising sodium aluminosilicate with a moisture level of less than 15%, preferably less than 10% by weight of the aluminosilicate.

5. A granular detergent composition according to any of the previous claims wherein the stilbene brightener component is selected from the group consisting of :
Disodium 4,4'-bis[(4-anilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate or
Tetrasodium 4,4'-bis[(4-sulfoanilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate
or mixtures thereof; wherein R is morpholino or diethanolamino.

6. A granular detergent composition according to any of the previous claims wherein the biphenyl or bis(benzoxazole) brightener component is selected from the group consisting of :
Disodium 4,4'-bis (2-sulphostyryl) biphenyl
Disodium 4,4-bis (4-chloro-3-sulphostyryl) biphenyl
Disodium 4,4'-bis(sulfobenzo[b]furan-2-yl)biphenyl 2,5-bis(benzoxazole-2-yl)thiophene
or mixtures thereof.

7. A granular detergent composition according to either of claim 5 or claim 6 wherein the stilbene brightener is disodium 4,4'-bis[(4-anilino-6-R-1,3,5 triazin-2-yl)amino]-2,2'-stilbenedisulphonate with R = morpholino or diethanolamino, and the biphenyl brightener is 4,4-bis (2-sulphostyryl) biphenyl.

8. A granular detergent composition according to claim 1 or claim 7, wherein the ratio of stilbene brightener to biphenyl/benzoxazole brightener is at least 5:1, preferably at least 6:1.