Bleaching and dyeing; fluid treatment and chemical modification – Fluid treatment – Manipulation of liquid
Reexamination Certificate
1998-03-05
2001-10-16
Stinson, Frankie L. (Department: 1746)
Bleaching and dyeing; fluid treatment and chemical modification
Fluid treatment
Manipulation of liquid
C068S01700R, C206S000500, C134S093000
Reexamination Certificate
active
06301733
ABSTRACT:
INTRODUCTION
The invention relates to a process for washing laundry in a washing machine by employing a receptacle for dispensing at least one detergent tablet, the receptacle being substantially rigid and having a plurality of apertures for permitting the passage of an aqueous solution there through, the process comprising the steps of placing the dispensing receptacle having at least one detergent tablet contained therein in a washing machine together with the laundry to be washed, and carrying out a washing operation. The invention also relates to a dispensing device for carrying out the above process.
Dispensing devices for detergent tablet compositions are known. For example DK-B-165 759 discloses a dispensing device having a flexible fluid permeable sleeve arranged in an enclosing manner about a rigid hollow body forming an annular chamber between the sleeve and the body, the body having an inlet opening for insertion of the tablet. EP-A1-0628 652 describes a similar dispensing device. Both of these devices include relatively complicated means for delivering a tablet from the opening in the hollow body to the annular chamber, are expensive to make and complicated in use.
EP-A1-0-473-532 discloses a further dispensing device for use with detergent tablets which comprises a water permeable fabric bag having a slotted opening and a freely movable body within the bag to effect the disintegration of the tablet. If, however, the fabric bag described above was analysed after a washing operation, a large number of detergent residues would be embedded in the material of the bag. This results in detergent being wasted and the bag having decreased water permeability.
EP O 699 410 discloses a dispenser for, primarily machine dishwash, detergent tablets which comprises an open topped rigid cage having pincers for picking up tablets. A problem with this device is that the apertures in the cage appear quite large and thus would allow large undissolved tablet particle escape into the wash to cause dye damage to the clothes. A further problems is the rather complicated structure.
EP 0 479 711 describes a further device comprising a two-part rigid sleeve having an outer sleeve of flexible water permeable material. In use a tablet is inserted between the rigid and flexible sleeves before the device is placed in a washing machine. Again this device is of quite complicated construction. Further it requires considerable dexterity for successful positioning of the tablet between the two sleeves.
EP 0 691 102 describes a cage dispenser for tablets having a child resistant closure. The apertures in the cage are quite large and would allow sizeable detergent particle escape into the wash.
EP O 610 535 discloses a fabric bag dispenser for powdered detergents, the bag having holes of a size sufficient to allow water penetrate but preventing the powder escape. The use of such a bag with detergent tablets would likely lead to poor break-up and dissolution of the tablet and result in a high level of residues left in the bag.
EP O 576 234 describes a tablet dispenser comprising an elastic net sleeve which, upon insertion of the tablets, conforms tightly to the tablets. A number of problems are associated with this dispenser. First, as the tablets are held by the sleeve in a face to face configuration, less of the tablets surface area is exposed to the wash water. This leads to a decreased rate of dissolution of the tablets which results in a greater level of detergent residues left in the machine after the wash. A consequence of this is an increased incidence of dye fading due to detergent residues or particles coming into direct contact with clothes. Second, as the net conforms tightly to the tablets, the tablets are firmly pushed against the net resulting in parts of the tablet being exposed through the net to the clothes in the wash. Such exposure will lead to increased levels dye damage. Furthermore, as the elastic net prevents the tablets moving around the net, mechanical disintegration of the tablets is reduced. Finally, as the net is elastic, the mouth of the sleeve tends to be quite small which makes insertion of the tablets difficult.
It is an object of the present invention to provide a dispensing device and washing process which overcomes at least some of the above problems.
STATEMENTS OF INVENTION
According to the invention, there is provided a laundry washing process of the above type, the process being characterised in that the apertures of the dispensing receptacle have an average dimension equivalent to a mesh size of between 1 mm and 10 mm.
Surprisingly, it has been found that as the equivalent mesh size of the apertures increases above 1 mm, that the incidence of dye damage, ie. the effect of direct contact between the tablet and the clothes, decreases. It would have been expected that as the size of the holes increased, the greater the dye damage would be due to the greater exposure of the tablet through the holes in the net. In practice, the opposite effect has been observed when the process of the invention is carried out.
A further surprising effect of the process of the present invention is that the incidence of detergent tablet residues remaining in the machine after a washing operation decreases. This is quite unexpected in so far as it would be assumed that, as the mesh size increases, the greater the number of undissolved residues would escape from the device into the wash. However, again, the opposite effect has been observed with the process of the invention.
The equivalent mesh size of the apertures of the device the present invention is limited to less than 10 mm. Mesh sizes above this figure result in large particles escaping into the wash. This is undesirable due to the increased incidence of dye damage which results.
In one embodiment of the process, the apertures have an average dimension equivalent to a mesh size at least 2 mm, ideally at least 3 mm, more preferably at least 4 mm and most preferably approximately 5 mm. Typically, the equivalent mesh size of the apertures net is at most 9 mm, ideally at most 8 mm, preferably at most 7 mm, and most preferably at most 6 mm.
Preferably the apertures of the device have an average dimension equivalent to a mesh size of approximately 5 mm.
In one embodiment of the invention, the detergent tablet comprises a tripolyphosphate composition, typically comprising a compacted particulate detergent composition containing one or more detergent-active compounds together with sodium tripolyphosphate and other ingredients, and in which the tablet or a region thereof comprises particles which contain sodium tripolyphosphate with a content of the phase 1 form which is more than 40% by weight of the sodium tripolyphosphate in said particles, wherein the sodium tripolyphosphate in said particles contains water of hydration distributed throughout the tripolyphosphate in an amount between 1% and 5% by weight of the sodium tripolyphosphate in the particles.
Alternatively, the detergent tablet may comprise sodium acetate trihydrate, optionally together with sodium citrate dihydrate. Such a composition may for example comprise a compacted particulate composition in which the tablet comprises a compacted particulate composition in which the tablet comprises a compacted particulate detergent composition comprising 2% to 35% by weight of a salt which is sodium acetate trihydrate, potassium acetate or mixture thereof, optionally together with sodium citrate dihydrate, such that the total quantity of sodium acetate trihydrate, potassium acetate and sodium citrate dihydrate is from 7% to 50% by weight of the tablet or a region thereof. Optionally, the tablet or a region thereof comprises from 15% to 93% by weight of a water softening agent.
The process according to the invention will preferably include a reusable receptacle which comprises an opening for reception of the detergent tablet and closure means for preventing the passage of the tablet out of the receptacle through the opening, the process thus including an initial step of placing one or m
Dawson George Thomas
de Jong Albert Cornelis
Delwel Francois
Gordon James William
Kerr Colin Watt
Lever Brothers, Division of Conopco, Inc.
Mitelman Rimma
Stinson Frankie L.
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