Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
1998-06-30
2001-04-24
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S321000, C510S393000, C510S418000, C510S441000, C510S475000, C510S476000, C510S477000, C510S530000
Reexamination Certificate
active
06221829
ABSTRACT:
This invention relates to liquid detergent concentrates which include polymeric particles (ie particles having an external surface of organic polymer) which give improved stability when dispersed in the concentrate.
Processes are described in PCT/GB96/03233 now WO 97/24179 for forming particulate compositions comprising particles having a hydrophilic core within a shell comprising a membrane comprising an association product of (a) an interfacial condensation (IFC) product formed by reaction in a non-aqueous liquid between a first IFC reactant having at least two first condensation groups and the second IFC reactant having at least two second condensation groups and (b) an amphipathic polymeric stabiliser which will concentrate at the interface between oil and water and which has recurring hydrophobic groups and recurring reactive hydrophilic groups which associate with the second condensation groups. After formation in the non-aqueous liquid, the particles are then dispersed in aqueous electrolyte.
It is explained in that application that the association may comprise a condensation reaction and, in particular, condensation may occur when the stabiliser is a copolymer of an ethylenically unsaturated carboxylic anhydride such as maleic anhydride and the second condensation groups are amino groups. It is also explained, however, that the association preferably comprises forming an internal, ring-formed salt between the adjacent carboxylic groups of a stabiliser formed from a monomer such as maleic acid or maleic anhydride with an IFC reactant which is a polyamine.
We have found that the best performance is generally achieved when the formation of the IFC shell does depend on the use of a polycarboxylic stabiliser which is in hydrolysed acid form rather than anhydride form, and this is probably due to the fact that internal salt formation occurs and that covalent reaction between the amine and the carboxylic acid groups does not occur during normal processing.
We have also found that when particles are made in this way, the resultant particles sometimes have less dispersion-stability than is desirable, especially when they are subsequently dispersed in an aqueous electrolyte solution (such as a liquid detergent concentrate).
We have found that, when developing these unpublished processes, it is difficult simultaneously to optimise the shell formation and the stability of the particles in the final liquid dispersion. We believe that this may arise because of there being different requirements for optimum shell formation and for optimum stability, and because of the differences in the continuous phase. We believe that optimum shell formation may often be promoted by some degree of ionic association between the stabiliser and IFC reactant groups, but we believe that materials which are optimum for undergoing this ionic association may give less satisfactory stability in the final dispersion. Conversely, materials which may give optimum stability in the final dispersion appear to give less adequate shell formation.
Our object, arising out of this unpublished work, is to try to obtain a better combination of properties during manufacture and during long term storage in the electrolyte.
Different types of dispersions are known from, for instance, GB-A-1,198,052, GB-A-1,231,634, GB-A-1,268,692, GB-A-2,207,681, AU-A-455,165, U.S. Pat. No. 3,580,880, U.S. Pat. No. 3,875,262, EP-A-707,018 and EP-A-719,085.
According to the invention, we provide a liquid detergent concentrate containing a dispersion of particles having a size below 30 &mgr;m wherein the particles have a shell core configuration, the shell has been made by interfacial condensation and has an outer surface which includes reactive groups, and a reactive stabilizer is covalently bonded with some of the reactive groups on to the surface of the particles. The dispersion is preferably substantially stable. The reactive stabiliser is preferably polymeric.
By saying that we covalently react the stabiliser material with some of the reactive groups, we mean that there is sufficient covalent bonding between the stabiliser material and the reactive groups to ensure that the stabiliser is attached to the particles by sufficient covalent bonding to hold the stabiliser material in place despite reasonable changes in the continuous phase in which the particles may be dispersed. For instance the stabiliser material should remain in place, and give a stabilising effect, even though the continuous phase may change from a first liquid which is a non-aqueous, predominantly hydrocarbon, liquid to the aqueous detergent concentrate. There can additionally be some ionic bonding or other forms of association but there must be sufficient covalent bonding to dominate the performance of the particles when the continuous phase is changed.
The number of reactive groups which remain unreacted after covalently reacting the stabiliser material on to the particles is often unimportant but in practice there will always be some reactive groups that do not react covalently with the stabiliser. For instance some of the reactive groups will be prevented from reacting because of steric hindrance between the stabiliser and the particle surface. Some of the reactive groups will be prevented from reacting covalently because they may react in another manner, for instance forming an ionic complex in practice some of the reactive groups may remain unreacted because there is a stoichiometric excess of reactive groups on the polymer particles over groups on the stabiliser that can react with them.
The particles have a size at least 90% by weight below 30 &mgr;m, preferably below 10 or 20 &mgr;m. The invention reduces or eliminates the risk of the particles sedimenting and/or aggregating, both at low concentrations (e.g., down to 0.1% by weight) and at higher concentrations (e.g., 5% or even much higher such as 30% or 50% in some liquids used for introducing the particles into the detergent concentrate.
Generally a substantially stable dispersion of the particles may be formed in a first liquid (usually a non-aqueous liquid) and then these particles may be dispersed into the liquid detergent concentrate and the dispersion would have been less stable in this if the covalent bonding of the invention had not been applied. In particular, by the invention the dispersion in the detergent concentrate is preferably more stable than if the same stabiliser material is simply mixed into the final dispersion of particles in the second liquid, without the covalent reaction. Generally the covalent reaction is conducted in the first (usually non-aqueous) liquid and the resultant self-stabilised particles are dispersed in the second liquid. However if desired the first liquid may be exchanged with another non-aqueous liquid (or some other liquid such as a surfactant) before the covalent reaction or even before adding the reactive stabiliser.
The change of the continuous phase from the first liquid to another liquid, and in particular to the detergent concentrate can be conducted in various ways, for instance as described in PCT/GB96/03233.
The particles may be made by interfacial condensation (IFC) in a first liquid as described in PCT/GB96/03233 and which is incorporated herein by reference.
The reactive groups on the polymer particles can be epoxide or hydroxyl groups (in which even the covalent bond will be an ether). They can be carboxylic groups (free acid, water soluble salt, anhydride or acid halide) in which event the covalent linkage can be an ester or amide linkage. Preferably, however, the reactive groups are amino groups in which event the covalent linkage is preferably an amide linkage, formed by reaction between these amino groups and carboxylic groups which can be covalently bonded with them.
Although covalent bonding can be achieved between carboxylic free acid, salt or halide groups and amino groups, the covalent reaction generally occurs much more easily if the carboxylic groups are in the form of anhydride groups and thus preferably the reactive groups are amino groups
Lykke Mads
Mistry Kishor Kumar
Simonsen Ole
Symes Kenneth Charles
Douyon Lorna M.
Novo Nordisk A S
Sughrue Mion Zinn Macpeak & Seas, PLLC
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