Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
1999-11-03
2001-07-10
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C264S117000, C264S118000
Reexamination Certificate
active
06258342
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to using a composition of water-soluble or water-swellable polymer agglomerated by treatment with water or an aqueous solution of the polymer and drying for making oral care compositions.
BACKGROUND OF THE INVENTION
Oral care compositions generally refer to dentifrice and dental adhesives. Dentifrice formulations generally contain dentally acceptable abrasive, humectant, water, and water-soluble polymer which serves as a thickener and binder for the ingredients. A variety of other ingredients such as flavors, color, vitamins, antiplaque, anti-tarter, breath freshener, color, sweeteners, preservatives and fluoride are also used at low levels. Glycerol and sorbitol (usually as an aqueous solution) are the most commonly used humectants for dentifrice, and depending on the characteristics desired in the product, polyethylene glycol or propylene glycol may be incorporated as well. Four types of dentifrice are widely produced: 1) cream, 2) transparent or translucent gel, 3) stripes of cream and gel, and 4) dry powders.
The thickeners or binders used for dentifrice are carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), silica, magnesium aluminum silicate, carrageenan, xanthan, guar, alginate, polyacrylic acids, salts of polyacrylic acids, polymers of ethylene oxide, copolymer of ethylene oxide and propylene oxide, processed euchemia seaweed (PES), starch, starch derivatives, pectin, and agar.
In the manufacturing process for dentifrice, incorporation of a dry water-soluble binder polymer into the composition often presents difficulties because of the tendency for lump formation when the dry polymers are added to and dispersed in aqueous systems. This increases the time required to obtain uniform hydration or uniform dispersion of the binder polymer. And sometimes, portions of the polymer could remain in dentifrice in partially hydrated gel form. This can not only affect dentifrice shelf stability and rheology but would also make dentifrice aesthetically unappealing. A re-occurring problem in the dentifrice industry is to make a polymer that is universally dispersible regardless of the environment in which it is to be used. Making a polymer dispersible based on a particular formulation has been done prior to the present invention but that makes a polymer formulation specific. Consequently, there is a need in the industry for a method of incorporating water-soluble binder polymers into dentifrice formulations universally which lead to dust-free and lump-free products, rapid viscosity development and reduced batch preparation time, and allow convenient handling of the binder.
U.S. Pat. No. 5,869,029 discloses a dentifrice composition using an agglomerated composition of a water-soluble polymer at least partially agglomerated by treatment with at least one polyol. U.S. Pat. No. 3,396,034 discloses a process of converting a hard to disperse particulate cellulose ether material or vegetable gum into a readily dispersible, dust-free particulate material by subjecting fine particles to water spray in an amount sufficient to cause superficial hydration. U.S. Pat. No. 4,557,938 discloses a process for preparing a dispersible agglomerated vegetable gum/carrier particles by dry blending particulate carrier, such as starch and the vegetable gum in a fluid bed dryer. The fluidized vegetable gum and starch particles are sprayed with water to wet the surface of the particles to cause agglomeration. U.S. Pat. No. 3,455,714 discloses the agglomerating of a water-soluble polymer with water-soluble cellulose ether that does not have a tendency to agglomerate when added to water. Japanese Patent No. 93075369 B discloses a method of spraying water onto water-soluble powdery paste under fluidized state and drying the formed granules. The starting powdery paste can be hydroxypropylcellulose or carboxymethylcellulose among other polymers.
None of the above patents discloses the use of water or aqueous polymer agglomerated water-soluble or water-swellable polymer in oral care compositions.
SUMMARY OF THE INVENTION
This invention relates to an improved process for preparing an oral care composition comprising of at least one dry, water-soluble or water-swellable polymer (excluding methylhydroxypropylcellulose alone), the improvement comprising substituting for the dry, water-soluble or water-swellable polymer, a particulate water-soluble or water-swellable polymer which has been at least partially agglomerated by treatment with water alone or an aqueous solution of a water-soluble polymer or polymers and drying. The particulate water-soluble or water-swellable polymer which has been at least partially agglomerated by such treatment with water alone or an aqueous solution of the water-soluble polymer and dried, hydrates in polyhydric alcohol, water, or water-containing solvents substantially faster than the corresponding untreated water-soluble or water-swellable polymer, without the formation of polymer lumps and being dust free.
DETAILED DESCRIPTION OF THE INVENTION
It was surprisingly found that a particulate water-soluble or water-swellable polymer at least partially agglomerated by treatment with water alone or an aqueous solution of the polymer and dried has greater dispersibility without producing dust and formation of polymer lumps in the preparation of oral care compositions. Agglomeration is defined herein as the aggregation of individual particles resulting in an increase in the particle size of the particulate material.
Any natural or synthetic water-soluble or water-swellable polymer may be employed to prepare the composition of this invention. Preferred water-soluble or water-swellable polymers are polysaccharides. Useful polysaccharides may include, but are not limited to, cellulose ethers, guar, guar derivatives, locust bean gum, psyllium, gum arabic, gum ghatti, gum karaya, gum tragacanth, carrageenan, Konjac, agar, alginates, xanthan, scleroglucan, dextran, pectin, starch, starch derivatives, chitin and chitosan.
Preferred polysaccharides are cellulose ethers, carrageenan, guar, guar derivatives and pectin.
Cellulose ethers for use in the invention include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), water soluble ethylhydroxyethyl cellulose (EHEC), carboxymethyl cellulose (CMC), carboxymethylhydroxyethyl cellulose (CMHEC), hydroxypropylhydroxyethyl cellulose (HPHEC), methyl cellulose (MC), methylhydroxypropyl cellulose (MHPC)(when used in combination with other polymers), methylhydroxyethyl cellulose (MHEC), carboxymethylmethyl cellulose (CMMC), hydrophobically modified carboxymethyl cellulose (HMCMC), hydrophobically modified hydroxyethyl cellulose (HMHEC), hydrophobically modified hydroxypropyl cellulose (HMHPC), hydrophobically modified ethylhydroxyethyl cellulose (HMEHEC), hydrophobically modified carboxymethylhydroxyethyl cellulose (HMCMHEC), hydrophobically modified hydroxypropylhydroxyethyl cellulose (HMHPHEC), hydrophobically modified methyl cellulose (HMMC), hydrophobically modified methylhydroxypropyl cellulose (HMMHPC), hydrophobically modified methylhydroxyethyl cellulose (HMMHEC), hydrophobically modified carboxymethylmethyl cellulose (HMCMMC), cationic hydroxyethyl cellulose (cationic HEC) and cationic hydrophobically modified hydroxyethyl cellulose (cationic HMHEC). Preferred cellulose ether is carboxymethyl cellulose.
Guar derivatives for use in the invention include carboxymethyl guar (CM guar), hydroxyethyl guar (HE guar), hydroxypropyl guar (HP guar), carboxymethylhydroxypropyl guar (CMHP guar), cationic guar, hydrophobically modified guar (HM guar), hydrophobically modified carboxymethyl guar (HMCM guar), hydrophobically modified hydroxyethyl guar (HMHE guar), hydrophobically modified hydroxypropyl guar (HMHP guar), cationic hydrophobically modified hydroxypropyl guar (cationic HMHP guar), hydrophobically modified carboxymethylhydroxypropyl guar (HMCMHP guar) and hydrophobically modified cationic guar (HM cationic guar).
More preferred polysaccharides for use in preparing the oral care compositions of
Harcum Weldon Wright
Modi Jashawant J.
Edwards David
Hercules Incorporated
Rose Shep K.
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