Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
2000-12-05
2002-11-12
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S489000, C423S335000, C423S339000, C106S272000, C106S288001, C106S502000, C051S307000, C051S308000, C051S309000
Reexamination Certificate
active
06479036
ABSTRACT:
This invention relates to particulate materials, such as synthetic amorphous silicas, especially precipitated silicas, for use in dentifrice compositions and especially for use as thickening agents in such compositions. The invention is also concerned with dentifrice compositions containing such particulate materials.
Dentifrice compositions contain a number of specific components, for example particulate materials such as amorphous silicas, fluoride sources, viscosity regulating agents, preservatives, humectants, surfactants, anti-plaque agents, anti-tartar agents, anti-hypersensitivity agents, colouring agents, water, flavour and other optional ingredients, the particulate materials being employed for their thickening and/or abrasive properties.
Typically the humectant system is based on an edible polyhydric alcohol, such as glycerine, sorbitol, polypropylene glycol, polyethylene glycol (PEG) or any suitable mixture thereof, to prevent the toothpaste from drying out. Optionally, polyethylene glycol can be employed to regulate the viscosity and cohesiveness of the formulation see for example U.S. Pat. No. 3,689,637. Compared with glycerine or sorbitol for example, PEG is a relatively expensive component of a dentifrice formulation.
According to one aspect of the present invention there is provided a particulate material for use in a dentifrice composition, the particulate material comprising silica particles to which a polyether glycol has been applied.
Preferably the silica particles have a relatively high structure so that they would already act as a thickening agent when incorporated in a dentifrice composition, if the polyether glycol had not been applied. Suprisingly, the application of the polyether glycol to the silica gives a further enhancement of thickening over a naked silica with the same structure, in a dentifrice formulation.
Some dentifrice formulations already contain a polyether glycol. By using silica particles to which a polyether glycol such as polyethylene glycol has already been applied, at least part of the polyether glycol employed in the dentifrice composition may be introduced through the agency of the particulate material. Surprisingly by intimately associating the polyether glycol with the particulate material, the amount required in the dentifrice composition can be reduced significantly to achieve a predetermined cohesion. In addition, by applying a suitable polyether glycol to the particulate material, the production of the particulate material by wet processing may be facilitated since the viscosity regulating agent may be beneficial to filtration efficiency.
According to a second aspect of the present invention there is provided a dentifrice composition, which includes water, humectant and a dispersed particulate material (preferably acting as a thickening agent), characterised in that the particulate material comprises silica particles to which a polyether glycol has been applied prior to incorporation of the particles in the composition.
Advantageously, it has been found that substantially less polyether glycol is required to provide a specific dentifrice cohesion, when the polyether glycol present in the dentifrice composition is carried by the silica particles rather than being present as a separate component within the dentifrice. In high water transparent toothpaste formulations, where good transparency can only be achieved in the absence of PEG, this is particularly advantageous. The removal of PEG from the formulation to achieve good transparency reduces the cohesion of dentifrice. The dentifrice cohesion can be recovered by incorporation of a silica of the invention in which the polyether glycol is carried by the silica.
Furthermore, a greater dentifrice cohesion can be achieved if the polyether glycol is carried by the silica, than if the same amount of polyether glycol is added as a separate component to the formulation. Also, the polyether treated silica particles provide a higher cohesion toothpaste than the same silica particles without polyether treatment, when incorporated at the same loading by weight.
The polyether glycol is typically constituted by polyethylene glycol and/or polypropylene glycol having an average molecular weight (i.e., number-average molecular weight in the range of 200 to 20,000. A presently preferred polyethylene glycol (PEG) is one having an average molecular weight in the range 4,000 to 12, 000, preferably 5,000 to 10,000 and more preferably about 5,000 to 7,000, e.g. about 6,000.
Usually the dentifrice composition will be in the form of a toothpaste, gel, cream or liquid, of the opaque, translucent or transparent variety. The exact physical properties of the dentifrice composition may be controlled for example by suitable adjustment of the water, humectant and dispersed particulate material (thickening silica).
The humectant component of the composition may comprise a polyol such as glycerol, sorbitol syrup, polypropylene glycol, lactitol, xylitol or hydrogenated corn syrup. The total amount of humectant may for example be in the range of 10 to 85% by weight of the composition.
The water content of the dentifrice composition typically ranges from 1 to about 90% by weight, preferably from about 10 to about 60% by weight, more preferably from about 15 to about 50% by weight. In the case of transparent pastes, a preferred range is from about 1 to about 35% by weight.
In preferred embodiments of the invention, the polyether glycol-carrying silica particles particulate material are present in the composition in a total amount of from about 0.1 to about 50% by weight; preferably from about 0.5 to 15% and most preferably from about 1 to 10% by weight.
The dentifrice composition of the invention may additionally comprise one or more additional components, such as those described below.
The composition of the invention may include one or more surfactants, preferably selected from anionic, non-ionic, amphoteric and zwitterionic surfactants, and mixtures thereof, all being suitable for dental and/or oral use. The amount of surfactant present in the composition of the invention is typically from about 0.1 to about 3% by weight (based upon 100% activity).
Suitable anionic surfactants may include soaps, alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkanoyl taurates, alkyl succinates, alkyl sulphosuccinates, N-alkoyl sarcosinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates and alpha-olefin suiphonates, especially their sodium, magnesium, ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups generally contain from 8 to 18 carbon atoms and may be saturated. The alkyl ether sulphates, alkyl ether phosphates and alkyl ether carboxylates may contain from one to 10 ethylene oxide or propylene oxide units per molecule, and preferably 2 to 3 ethylene oxide units per molecule. Examples of preferred anionic surfactants include sodium lauryl sulphate, sodium dodecylbenzene sulphonate, sodium lauroyl sarcosinate and sodium coconut monoglyceride sulphonate.
Non-ionic surfactants which may be suitable for use in the composition of the invention include sorbitan and polyglycerol esters of fatty acids, as well as ethylene oxide/propylene oxide block copolymers.
Suitable amphoteric surfactants include betaines such as cocamidopropyl betaine and sulphobetaines.
The dentifrice composition of the invention may also incorporate suitable well known polymer suspending or thickening agents such as polyacrylic acid, copolymers and cross-linked polymers of acrylic acid, copolymers of acrylic acid with a hydrophobic monomer, copolymers of carboxylic acid-containing monomers and acrylic esters, cross-linked copolymers of acrylic acid and acrylate esters, esters of ethylene glycol or esters of polyethylene glycol (e.g. fatty acid esters thereof, heteropolysaccharide gums such as xanthan and guar gums, and cellulose derivatives such as sodium carboxymethyl cellulose. Particularly suitable thickening agents are as mixtures of two or more of the above materials)
Evans Charlotte R
Stanier Peter W
Crosfield Limited
Pillsbury & Winthrop LLP
Rose Shep K.
LandOfFree
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