Abrasive tool making process – material – or composition – With inorganic material – Clay – silica – or silicate
Reexamination Certificate
2000-08-28
2003-05-13
Rose, Shep K. (Department: 1614)
Abrasive tool making process, material, or composition
With inorganic material
Clay, silica, or silicate
C051S307000, C051S309000, C424S049000
Reexamination Certificate
active
06562090
ABSTRACT:
This invention relates; to a stable, fluid suspension of an abrasive material, a process for preparing such suspension, and the use thereof in dentifrices
BACKGROUND OF THE INVENTION
Prior to the present invention, it was difficult to suspend abrasive materials for use in the dentifrice industry and consequently the amount of abrasive material in wet compositions was inconsistent. The normal manner of using the abrasive was to suspend it in water and then mix it with the other components. In this manner, especially when high volumes of abrasive were used, the abrasive would some times settle out causing the amount of abrasive in the final composition to vary from batch to batch. Another option for getting the abrasive in the final dentifrice composition was to use a dry powder abrasive. Although this produced consistent compositions, dusting problems were often experienced resulting in a longer toothpaste production process. The longer preparation time is due to the fact that the abrasive, such as calcium carbonate, had to be added slowly over a certain period of time to minimize dusting as well as agglomeration of finely divided particles upon contact with the dentifrice gel premix. Dusting also created safety and health hazards by making the floor where the composition was being prepared slippery so that accidents could occur. Also, this dusting was a health problem for the workers who had to inhale this dust creating respiratory problems.
For the above reasons, plant operators desire a fast, effective, consistent, and simple way to incorporate abrasives into a dentifrice system. In other words, to reduce production costs as well as dusting in current toothpaste production, it is desirable to deliver a slurry or a fluid system (i.e., suspension or dispersion) of the abrasive. The use of such a slurry or fluid system will also allow manufacturers to use a continuous and/or batch production process that is efficient.
SUMMARY OF THE INVENTION
The present invention is directed to a fluid suspension consisting essentially of a) an abrasive, b) a suspending vehicle, and c) a water-swellable or water-soluble polymer.
The present invention also relates to a method of making a fluid suspension comprising dispersing and hydrating a polymer in a suspending vehicle of water or polyhydric alcohol or mixtures thereof and adding an abrasive to form the fluid suspension. Also, this system can be prepared in the reverse order by adding the abrasive to the suspending vehicle and then adding the polymer thereto. The fluid abrasive suspension can also be prepared by mixing in dry form a polymer and a abrasive to form a mixture and then adding a suspending vehicle of water, polyhydric alcohol, or mixtures thereof to said mixture and stirring to form the fluid suspension. Also, the fluid suspension can be prepared adding the ingredients in the reversed order, i.e., mixing the polymer and the abrasive, either together or alone, into the suspending vehicle.
The present invention also comprehends a method of making a dentifrice comprising adding to the above mentioned fluid abrasive suspension composition the desired dentifrice formulation ingredients. Again, the reverse order of addition can be used in that the desired dentifrice formulation ingredients can be added either alone or together to the fluid abrasive suspension mentioned above.
DETAILED DESCRIPTION OF THE INVENTION
It has been surprisingly found that abrasives could be made into stable fluid suspensions for a more efficient and consistent handling and use in the dentifrice industry. These suspensions have a long shelf life and thus can be shipped or pumped without the problems associated with settling. Another advantage of these fluid abrasive suspensions (FAS) is that since these FAS are made up of ingredients that are used in dentifrice, they are compatible and do not use ingredients that would be superfluous to dentifrice.
In accordance with this invention, the terms “suspension” and “dispersion” are used interchangeably to mean a system in which solid particles, the abrasive, are dispersed or suspended in a suspending vehicle of water or polyhydric alcohol or mixtures thereof to form a stable dispersion. Also, a “solution” is a homogeneous, single-phase mixture of a solvent such as water and a soluble material that is completely dissolved in the solvent. A “slurry” is defined as a liquid and an insoluble, solid material that forms a flowable mixture (such as mud or plaster of Paris).
A dentifrice is commercially available in four forms: powder, paste, gel, and liquid. The present invention is directed to all of the forms except powder. These forms are generally referred to as toothpaste. Hence, in this invention, the terms “dentifrice” and “toothpaste” will be used interchangeably.
The fluid abrasive suspension (FAS) of the present invention includes an abrasive, a suspending vehicle, and a water-swellable or water-soluble polymer. The FAS may also contain at least one other ingredient that may be used in dentifrices such as perservatives, fluoride, buffering agent, humectant, coloring agent, flavor, sudsing agent, detergent, salts, tartar control, sweetener, vitamin, whitening agent, antiplaque agent, anticalculus, sequestering agent, and odor removers.
Unless otherwise mentioned, all of the amounts in the FAS are based on the total weight of the FAS.
Abrasives
In accordance with the present invention, the FAS contains a lower limit of the abrasive of 5 weight percent on the total weight of the FAS, preferably 15 weight percent, and more preferably 30 weight percent. The upper limit in the FAS is 70 weight percent, preferably 60 weight percent, and more preferably 45-weight percent. In toothpaste, abrasives of various types can provide the unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentin. The abrasive materials must also be exceptionally compatible with sources of soluble fluorides. Hence, it is important that the correct amount of abrasive be in the toothpaste so that it can perform its intended purpose well.
In accordance with this invention, the bulk density of the abrasive polishing material should be in a specific range. If the bulk density is too low, it becomes more difficult to incorporate the abrasive into the suspension system. If the bulk density is too high, it becomes impractical to handle and use. Hence, there is a desirable range that should be used. This makes it easy for processing and pumping the abrasive from one stage to the next in the making of a dentifrice formulation. The lower limit of the bulk density is about 0.2 gram per milliliter (g/ml), preferably 0.4 g/ml, and more preferably 0.6 g/ml. The upper limit of the bulk density is about 1.2 g/ml, preferably 1.0 g/ml, and more preferably 0.8 g/ml.
Examples of abrasive materials that can be used in this invention are calcium carbonate, calcium phosphate, sodium meta phosphate, sodium bicarbonate, calcium pyrophosphate, dicalcium phosphate, silica, and alumina. The preferred abrasives are calcium carbonate, especially precipitated calcium carbonate (PCC), dicalcium phosphate (Dical), and silica.
Suspending Vehicle
In accordance with the present invention, the suspending vehicle of the FAS can be water, a polyhydric alcohol, or mixtures thereof. Water used in this invention should preferably be deionized or demineralized and free of organic impurities. When water is used alone in the FAS, it should have a lower limit amount of 25% by weight of the FAS formulation, preferably 35% and more preferably 45%. The upper limit for the water should be 90%, preferably 75% and more preferably 60%.
Some examples of the polyhydric alcohols which can be used with water are: sorbitol, glycerol, propylene glycol, polyethylene glycol, ribitol, xylitol, mannitol, poloxamer, and mixtures thereof.
The anhydrous polyhydric alcohols (PHALC) which can be used alone for FAS without presence of water are: propylene glycol (PG), polyethylene glycol (PEG), glycerol (G), and poloxamer (PXMR). For example, PG and PEG c
Melbouci Mohand
Modi Jashawant J.
Edwards David
Hercules Incorporated
Rose Shep K.
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