Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
1999-11-18
2002-04-09
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S276000, C510S351000, C510S444000, C510S495000, C510S507000, C510S511000, C510S498000, C510S477000
Reexamination Certificate
active
06369020
ABSTRACT:
TECHNICAL FIELD
The present invention relates to granular detergent components containing heat-sensitive surfactants, especially alkyl ether sulphates, and particulate laundry detergent compositions containing them.
BACKGROUND AND PRIOR ART
Alkyl ether sulphates (alkyl polyethoxy sulphates) are desirable ingredients for laundry detergent compositions. They are relatively insensitive to calcium ions and are frequently used in combination with more calcium-sensitive anionic surfactants such as linear alkylbenzene sulphonates as a supplementary surfactant or “coactive”.
However, alkyl ether sulphates cannot be processed at elevated temperatures because of a tendency to decompose significantly at temperatures higher than 80° C. They are not, therefore, generally incorporated into spray-dried laundry powders via the slurry.
Similar considerations apply to other heat-sensitive surfactants (anionic, cationic, amphoteric or zwitterionic) that are usefully incorporated into laundry detergent compositions.
It is therefore desirable to incorporate these surfactants as a separate granular component in which the surfactant is carried on a suitable carrier material.
Highly effective methods of producing free-flowing granular detergent components containing high levels of anionic surfactants (for example, alkylbenzene sulphonates) are disclosed in WO 96/06916A, WO 96/06917A, WO 97/32002A and WO 97 32005A (Unilever). However, these processes involve flash drying of aqueous pastes at temperatures above 130° C., and are therefore unsuitable for processing alkyl ether sulphates and other heat-sensitive surfactants.
It has now been found that stable free-flowing granules containing high loadings of heat-sensitive anionic, cationic, amphoteric or zwitterionic surfactants can be prepared using a carrier comprising a highly oil-absorbent silica or silicate, and a defined structurant.
WO 98 54281A (Unilever), published on Dec. 3 1998, discloses granular detergent components containing high levels of nonionic surfactants. These granules utilise as carrier material a silica having a high oil absorption capacity. In addition to the nonionic surfactant, the granules may contain up to 5 wt % of anionic surfactant.
EP 430 603A (Unilever) discloses detergent granules containing at least 30 wt % anionic surfactant and containing a highly oil-absorbent filler, for example, a silica, in intimate contact with the anionic surfactant.
WO 97 10321A (Procter & Gamble) discloses structured surfactant compositions comprising 35-60 wt % surfactant, preferably alkyl ether sulphate, 1-20 wt % hydrophilic finely-divided silica and 15-25 wt % moisture; these compositions are in the form of a “hardened continuous paste”.
EP 105 160A (Akzo) discloses silicas loaded with aqueous surfactant solutions, preferably primary alcohol sulphate, alkyl ether sulphate or nonionic surfactant, for use in toothpastes; the highest surfactant loading disclosed in in a free-flowing granule is 20 wt %, higher loadings being detrimental to flow.
EP 651 050A (Procter & Gamble) discloses detergent agglomerates comprising a solid, preferably water-soluble, salt (for example, sodium silicate, carbonate or sulphate), and a fluid binder comprising an anionic surfactant (preferably alkyl ether sulphate) and sodium silicate.
DEFINITION OF THE INVENTION
A first subject of the present invention is a free-flowing granular detergent component comprising
(a1) at least 30 wt %, preferably 30 to 75 wt %, of a heat-sensitive anionic, cationic, amphoteric or zwitterionic detergent surfactant,
(a2) from 15 to 50 wt % of a water-insoluble carrier material comprising a silica or silicate having an oil absorption capacity of at least 1.0 ml/g,
(a3) from 2 to 15% by weight of a structurant which is a water-soluble material capable of drying from aqueous solution and/or solidifying from the melt to form a crystalline and/or amorphous film.
The invention also provides a process for preparing the granular detergent compound, as described in more detail below.
A further subject of the invention is a particulate detergent composition composed of at least two different granular components:
(a) a granular component as defined above,
(b) at least one other granular component selected from
(b1) a detergent base powder composed of structured particles comprising anionic surfactant, builder, optionally nonionic surfactant and optionally other detergent ingredients,
(b2) a builder granule, and
(b3) a granule containing at least 40 wt % of alkylbenzene sulphonate and/or primary alcohol sulphate,
(b4) a granule containing at least 20 wt % of nonionic surfactant.
The Granular Detergent Component
The granular detergent component comprises at least 30 wt %, and preferably from 30 to 75 wt %, more preferably from 40 to 75 wt %, of the heat-sensitive surfactant.
The heat-sensitive surfactant may be anionic, cationic, amphoteric or zwitterionic. For the purposes of the present specification a surfactant is “heat-sensitive”, if it undergoes significant decomposition at temperatures above 80° C.
Preferred heat-sensitive anionic surfactants are alkyl ether sulphates.
The granule also contains from 15% to 50 wt % of by weight of a silica or silicate carrier material having an oil absorption capacity of at least 1.0 ml/g. Oil absorption capacity is a parameter which is well known and can be measured by the technique described in DIN ISO 787/5. Preferably, the oil absorption capacity is at least 1.5 ml/g, more preferably at least 2.0 ml/g.
Preferably, the granule contains at least 20% of the silica or silicate carrier material.
The silica or silicate carrier material is preferably selected from silicas, magnesium silicate, calcium silicate, and amorphous alkali metal aluminosilicates.
Silicas and silicates having the required oil absorption capacity are commercially available, for example:
LCC
Material
Supplier
(ml/g)
Sorbosil TC-15
Silica
Crosfield
2.8
Hubersorb 600
Calcium silicate
Huber
4.8
Sipernat D17
Silica
Degussa
2.3
Sipernat 50
Silica
Degussa
3.3
Aerosil 380
Silica
Degussa
3.5
Zeosyl 200
Silica
Huber
2.6
Optionally, the granule may also contain a crystalline alkali metal aluminosilicate (zeolite). The amount of zeolite present may suitably range from 2 to 20 wt %, preferably from 5 to 15 wt %.
The zeolite which may be used in the nonionic-surfactant-containing granules of the present invention may be the commercially available zeolite A (zeolite 4A) now widely used in laundry detergent powders. This is commercially available, for example, as Wessalith (Trade Mark) P from Degussa AG.
Alternatively, maximum aluminium zeolite P (zeolite MAP) as described and claimed in EP 384 070B (Unilever), and commercially available as Doucil (Trade Mark) MAP from Crosfield Chemicals Ltd, UK, may be used. Zeolite MAP is defined as an alkali metal aluminosilicate of zeolite P type having a silicon to aluminium ratio not exceeding 1.33, preferably within the range of from 0.90 to 1.33, preferably within the range of from 0.90 to 1.20.
Zeolites have a substantially lower liquid carrying capacity than do the silicas or silicates which are the principal carriers in the granules of the invention. For example, the liquid carrying capacity of zeolite MAP is 0.6 ml/g.
The granules of the present invention also contain a structurant, which may also be considered as a binder, in order to improve the strength and flow of the granules. The structurant, present in an amount of from from 2 to 15 wt %, is a material capable of drying from aqueous solution and/or solidifying from the melt to form a crystalline and/or amorphous film.
The granular detergent component may, for example, comprise as structurant a water-soluble film-forming material selected from soaps, sugars, water-soluble polymers, alkali metal silicates and combinations thereof. Preferred examples include glucose, maltose, ethylene glycol homo- and copolymers, polyvinyl alcohols (preferably of molecular weight 30,000 to 200,000), polyacrylates (preferably of molecular weight 30,000 to 200,000), and acrylic/maleic copolymers (eg Sokalan (Trade Mark)
Kohlus Reinhard
Verburgh Remy Antal
Verschelling Gilbert Martin
Douyon Lorna M.
Mitelman Rimma
Unilever Home & Personal Care USA
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