Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
1999-01-04
2001-01-09
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S357000, C510S451000, C510S495000, C264S117000, C264S140000
Reexamination Certificate
active
06172033
ABSTRACT:
The invention relates to a process for making a granular detergent component or composition.
Manufacturing processes are known wherein granular detergent products are made by forming a neutral or alkaline paste comprising at least 40% by weight of anionic surfactant; and mixing the high viscosity paste so-formed with builder powders wherein the ratio of high viscosity paste to builder powder is from 9:1 to 1:5 to form the granular detergent component or composition. Such processes are commonly called agglomeration processes
EP-A-0 663 439, published on Jul. 19, 1995, and EP-A-0 508 543, published on Oct. 14, 1992, both describe enhanced embodiments of agglomeration processes which includes a process of surfactant paste conditioning in, for example, a twin-screw extruder, followed by granulation in a high shear mixer.
EP-A-0 508 543 mentions the possibility to add anionic surfactant into the process via a powder stream. However it is not specified whether this powder stream is added into the extruder, or into the high-shear mixer. Neither of these publications describes the use of dry alkyl sulphate powder in the conditioning step.
The object of the present invention is to provide an effective process for conditioning pastes comprising at least 40% by weight of anionic surfactant. The conditioning agent disrupts surfactant crystallinity, and also increases the viscoelasticity of the paste. The crystalline disruption improves rate of surfactant solubility, whilst the viscoelasticity increase “conditions” the paste enabling agglomerates with high surfactant activity to be formed. The paste is processed into agglomerates by granulating with builder powders wherein the ratio of high viscosity paste to builder powder is from 9:1 to 1:5.
SUMMARY OF THE INVENTION
The object is achieved by mixing a first powder with the surfactant paste in a ratio of at least 1 part powder to 100 parts paste, the first powder comprising at least 80% by weight of alkyl sulphate, and whereby the mixing step increases the viscosity of the surfactant paste.
In a preferred embodiment of the invention, alkyl sulphate powder, comprising less than 5% by weight of water, is mixed with other surfactants in the paste in an extruder. In an even more preferred embodiment of the invention the paste and alkyl sulphate powder mixture is carried out sequentially in a high-shear mixer granulator having a tool tip-speed of from 5 to 50 m/sec, and a medium speed agglomerator.
Most preferred builder powders are carbonate, aluminosilicate and silicate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention concerns conditioning of anionic surfactant in an aqueous, highly concentrated solution of its salt, preferably its sodium salt. These high active, low moisture surfactant pastes are of a high viscosity but remain pumpable at temperatures at which the surfactants are stable. In other processes, anionic surfactants or mixtures comprising at least one anionic surfactant, where highly viscous liquid crystal phases occur, requires that either lower viscous crystal phases be formed or that some viscosity modifiers are used. This requires expensive additives, and prevents high surfactant activities from being achieved.
Conditioning of a paste means the modifying of its physical characteristics to form higher active, less sticky agglomerates which are not easily obtainable under normal operating conditions. Conditioning of the paste as defined herein, means: a) increasing its apparent viscosity, b) increasing its effective melting point, c) increasing the “hardness” of the paste. The hardness/softness of the paste may be measured by a softness penetrometer according to ASTM D 217-IP50 or ISO 2137. The hardness of conditioned paste measured in this way should be less than 2cm, preferably less than 1cm.
Chemical conditioning agents are compounds that alter the physical structure and/or physical characteristics of the surfactant paste when added to the paste. In the present invention the chemical conditioning agent is alkyl sulphate in powdered form. It has been found that the addition to the surfactant paste reduces the stickiness of the paste, increases its viscosity and increases its softening point. This allows for more paste to be added during the agglomeration process thus leading to higher active agglomerates, preferably between 40% and 60%, more preferably greater than 50%. This method of treating the surfactant paste can be performed batchwise and continuous, preferably continuously.
Alkyl sulphate powder is defined herein as any free-flowing powder, flakes, noodles or needles which comprises at least 80% by weight of alkyl sulphate. Useful powders are commercially available from Albright & Wilson, Hickson Manro and Sidobre Sinnova. Alternatively suitable powders may be prepared by sulphating an alcohol, followed by neutralisation with, for example aqueous sodium hydroxide, then drying in a suitable spray drying tower, wiped film evaporator or suitable dryer. Dry neutralisation methods may also be used, neutralising alkyl sulphuric acid with, for example powdered sodium carbonate.
In a preferred embodiment of the invention an extruder is used to condition the paste. The extruder is a versatile piece of equipment which enables two or more pastes and the alkyl sulphate powder to be mixed
Process aids may also be used. Preferred process aids which may be mixed with the surfactant paste are starch, soap, fatty acids and polymers. Process aids and surfactant paste may be mixed prior to the extruder in, for example, a high shear mixer; or in the extruder itself.
THE PASTES
One or various aqueous pastes of the salts of anionic surfactants is preferred for use in the present invention, preferably the sodium salt of the anionic surfactant. In a preferred embodiment, the anionic surfactant is preferably as concentrated as possible, (that is, with the lowest possible moisture content that allows it to flow in the manner of a liquid) so that it can be pumped at temperatures at which it remains stable. While granulation using various pure or mixed surfactants is known, for the present invention to be of practical use in industry and to result in particles of adequate physical properties to be incorporated into granular detergents, an anionic surfactant must be part of the paste in a concentration of above 40%, preferably from 40-95%.
It is preferred that the moisture in the surfactant aqueous paste is as low as possible, while maintaining paste fluidity, since low moisture leads to a higher concentration of the surfactant in the finished particle. Preferably the paste contains between 5 and 40% water, more preferably between 5 and 30% water and most preferably between 5% and 20% water.
It is preferable to use high active surfactant pastes to minimize the total water level in the system during mixing, granulating and drying. Lower water levels allow for: (1) a higher active surfactant to builder ratio, e.g., 1:1; (2) higher levels of other liquids in the formula without causing dough or granular stickiness; (3) less cooling, due to higher allowable granulation temperatures; and (4) less granular drying to meet final moisture limits.
Two important parameters of the surfactant pastes which can affect the mixing and granulation step are the paste temperature and viscosity. Viscosity is a function, among others, of concentration and temperature, with a range in this application from about 5,000 cps to 10,000,000 cps. Preferably, the viscosity of the paste entering the system is from about 20,000 to about 100,000 cps. and more preferably from about 30,000 to about 70,000 cps. The viscosity of the paste of this invention is measured at a temperature of 70° C.
The paste can be introduced into the mixer at an initial temperature between its softening point (generally in the range of 40-60° C) and its degradation point (depending on the chemical nature of the paste, e.g. alkyl sulphate pastes tend to degrade above 75-85° C.). High temperatures reduce viscosity simplifying the pumping of the paste but result in lower active agglomerates. In
Goovaerts Lucas
Hailu Liben
Douyon Lorna M.
Dressman Marianne
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
LandOfFree
Process for conditioning of surfactant pastes to form high... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for conditioning of surfactant pastes to form high..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for conditioning of surfactant pastes to form high... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456493