SE436738B - ABRASIVE COMPOSITION AND SET FOR ITS PREPARATION - Google Patents

Description

“Ïö fi ß fi i * in ke has an excessively abrasive and damaging effect on the tissues of the oral cavity.

In addition to abrasives, therapeutic toothpastes normally contain fluoride ion-containing materials. The beneficial reduction in the incidence of dental caries obtained by topical application to tooth enamel surfaces of solutions containing fluoride ions is well known. Especially at pH values in a solution between about 4 and 8, fluoride ions are assumed to interact with enamel in such a way that the solubility in acid is reduced in such enamel. Enamel, treated in this way with fluoride, is more resistant to the development of dental caries. Therapeutic toothpaste compositions are therefore formulated in such a way that they provide access to fluoride ions in the solutions formed in the oral cavity during toothbrushing.

It has been assumed that the effectiveness of the fluoride treatment in achieving enamel dissolution and anti-caries effects depends on the amount of fluoride ion available for uptake of the enamel being treated. It is therefore of course desirable to formulate toothpaste compositions which provide maximum availability of fluoride ions in the solutions formed upon brushing the teeth thereby. However, efforts to utilize such fluoride ion-containing caries-preventing agents in toothpastes suitable for home use have not led to the theoretical maximum amount of soluble fluoride due to the tendency of fluoride ions to be inactivated and thereby no longer be available for inclusion in the enamel. That is, toothpastes lose during storage (at a rate that increases with temperature) the ability to give the theoretically maximum amount of soluble fluoride. In the context of the present invention, the "soluble fluoride" content of any given toothpaste composition refers to the concentration of fluoride ion in ppm found in the clear sample solution obtained when a slurry of toothpaste in water (weight ratio 1: 3 between toothpaste and water) are centrifuged.

Fluoride ionic raw materials have a tendency to interact with impurities in toothpaste and with such components therein as e.g. abrasives, buffering agents, etc. This interaction reduces the ability of the fluoride raw material to provide "soluble fluoride" in use. The propensity of the toothpaste compositions in question to maintain their soluble fluoride levels after b80 storage is expressed below as "toothpaste fluoride compatibility". The toothpaste fluoride compatibility of a particular toothpaste composition is thus the percentage of the theoretical maximum amount of the fluoride raw material that is actually measured as soluble fluoride after storage for a specified time and at a specified temperature (eg one week at 49 ° C). Similarly, it tends to express such a land compound as, for example, the agent to interact with the fluoride feedstock, so that the measured "soluble fluoride" content decreases relative to the theoretical maximum amount of the fluoride feedstock (especially in the presence of those below). The abrasive penetrants described in detail as "abrasive-fluoride compatibility" The methods used herein to determine "toothpaste-fluoride compatibility" values and "abrasive-fluoride compatibility" values are described in more detail below.

A toothpaste component, which can cause special difficulties in the formulation of fluoride-containing toothpastes, is a precipitated silica abrasive component. Precipitated silica abrasives are suitable for use in toothpastes, as they have desirably low abrasion values in terms of tooth substance. Some prior art precipitated silica abrasives are generally compatible with soluble fluoride materials but do not have a high enough abrasive effect to achieve effective cleaning results. Some other prior art precipitated silica abrasives provide acceptable cleaning results but have low abrasive fluoride compatibility according to the results obtained by measurements by the method described below. It should therefore be the case that no prior art precipitated silica abrasives provide both high "abrasive fluoride compatibility" and acceptable cleaning power (as evidenced by standard RDA values - RDA - Radioactive Dentin Abrasion - Grabbenstetter et al., Jour. Of Dental Research, eel, 1060, 1958).

Thus, there is a clear need to prepare precipitated silica abrasives which exhibit high "abrasive fluoride compatibility" in conjunction with acceptable cleaning performance. Thus, it is an object of the present invention to provide precipitated silica abrasives which exhibit high abrasive fluoride compatibility and in addition acceptable cleaning effect.

Another toothpaste component, which can be particularly detrimental to the soluble fluoride content of certain toothpaste compositions, is soluble phosphate. Soluble phosphates, in the use of toothpaste, serve to increase the ability of fluoride ions to penetrate the dental membrane ("denta1 pellicle film"). For this reason, soluble phosphates are suitably incorporated into fluoride-containing toothpaste compositions. However, especially in combination with silica dentifrices, soluble phosphate dentifrices have a tendency to promote loss of soluble fluoride in toothpaste, which contains these materials and therefore the toothpastes give low toothpaste-fluoride compatibility values. Thus, there is a clear need to formulate precipitated silica abrasives, which provide high toothpaste-fluoride compatibility when used in fluoride-containing toothpastes containing soluble phosphates as dentifrice penetrants. Thus, there is an additional need to provide fluoride-containing toothpastes which may contain precipitated silica abrasives in soluble phosphates. Therefore, it is an object of the invention to provide fluoride-containing toothpaste compositions which contain soluble phosphates and precipitated silica abrasives and which nevertheless retain relatively high levels of soluble fluoride even after a certain period of storage.

It has surprisingly been found that the objects described above can be realized by means of the present invention, which provides a new, precipitated silica abrasive, which has been treated with an alkaline earth metal material, in particular calcium. By utilizing the topical abrasives in question, such fluoride-containing toothpastes - in particular those embodiments which contain soluble phosphates - can be realized, which have a high toothpaste-fluoride compatibility and excellent cleaning effect.

It is of course well known that therapeutic toothpaste compositions contain calcium phosphate material as abrasives, but these calcium materials are present in large amounts as described above and are illustrated e.g. in U.S. Patent Nos. 3,624,199 and 3,864,471. Toothpaste compositions have also been previously described, which contain small amounts of alkaline earth metal ions, such as e.g. calcium ions, and compositions of this type are illustrated in U.S. Pat. No. 3,991,177. This patent discloses toothpaste compositions which contain a stabilizer activator for a dextranase enzyme agent, the stabilizer activator being a salt, e.g. calcium chloride, which is present in an amount of 0.001-0.3% by weight. This composition may also contain therapeutic fluoride and the abrasive is calcium carbonate. 7802901 * lf UT Toothpaste compositions, containing alkaline earth metal compounds or ions, are also described in U.S. Pat. Nos. 3,095,356, 3,122,483, 3,669,221, 3,782,446, 3,842,168 and 3,609,537.

However, none of these patents disclose therapeutic toothpaste compositions which contain as an abrasive a low structure precipitated silica containing about 10 -3 ppm of alkaline earth metal ion, as described herein.

The invention thus relates to a new abrasive composition intended for tan paste compositions, which is characterized in that it consists essentially of a precipitated, amorphous silica, which is prepared by charging at least a part of used alkali metal silicate in freshly prepared aqueous solution to a reaction vessel with acidification and acidification. acid, possibly at the same time as the remaining proportion of the silicate solution, which silica intimately reacted with a salt of an alkaline earth metal to form 10-300 ppm of alkaline earth metal ions in the amorphous silica exhibiting an RDA value. those of at least 40, a (compact) density of u, 24-0,55 g / ml, an oil absorption of 70-95 cm3 / 100 g, a BET surface area of 100-250 m2 / g and an annealing loss of 4-6%.

Furthermore, a method is prepared for the preparation of the new abrasives according to the invention, which generally consists in the formation of a low-structured silica by acidifying certain freshly prepared sodium silicate aqueous solutions with a mineral acid and subsequent treatment of the obtained wet cake with the required amount of alkaline earth metal ions.

The invention thus also relates to a method of preparing an abrasive composition according to the above, which method is characterized in that an aqueous solution of an alkali metal silicate with a SiO 2 / X 2 O molar ratio of 2.0 - 2.7 is formed, where X represents alkali metal , at a reaction temperature in the range of 7700 to 91 ° C, charging at least a part of the silicate solution to a reaction vessel and acidifying with a mineral acid, possibly simultaneously with the remaining part of the silicate solution, until the precipitation of silica is substantially complete. , after which the addition of mineral acid is continued until the pH value is 6.0 or below, decomposes at a temperature which is 10 ~ 30oC higher than the reaction temperature for a period of 10-30 minutes, filters the resulting slurry and washes 7802901- * 4 the solid product with fresh water, resuspend the resulting wet cake in water and add sufficiently alkaline soil under stirring conditions metal ion in the form of a sufficiently soluble alkaline earth metal salt in an amount sufficient to add to the wet cake alkaline earth metal ions in an amount of -300 ppm, based on the dry, recoverable product in the slurry, stirs the resulting mixture to effect adhesion. of the effective degree of treatment with alkaline earth metal on the surface of the silica and finally dries and extracts the solid product.

The abrasive composition according to the invention is used for fluoride-containing toothpaste compositions which show minimal loss of soluble fluoride when stored at normal temperatures and which give an excellent cleaning effect. Such toothpaste compositions comprise the amorphous precipitated silica abrasives of the invention, a flucride ion material, a binder, a humectant and water. Such toothpastes give a pH value of about 4.0-8.0, when they are slurried with water in a weight ratio of 1: 3 between toothpaste and water. The amorphous, precipitated silica abrasives of the invention are present in the toothpastes in an amount of about 6-35% by weight. The fluoride ion material constitutes about 0.01-3.0% by weight of the toothpaste compositions and can be any water-soluble material which gives fluoride ions in aqueous solution. The binder makes up about 0.2-2% of the toothpastes. The humectant is included in the toothpaste in an amount of about 5-55 weight-E.

The water in the toothpastes in question constitutes about 15-80% by weight of the composition.

The present invention thus relates to new, precipitated silica abrasives for use in toothpastes and to methods of making these abrasives. The resulting toothpaste compositions have excellent toothpaste-fluoride compatibility values and excellent abrasive values. In addition to the abrasive component, they contain as water constituents a water-soluble, fluoride-containing material, a binder and certain amounts of humectants and water.

All these components as well as optional ingredients, composition use and composition preparation are described in more detail below.

The invention relates to low-precipitation silica materials which are suitable for use as dental abrasives. Such abrasives have ultimately been combined with 10-300 ppm, preferably -100 ppm, alkaline earth metal, preferably calcium, based on the amount of recoverable dry matter. This tooth abrasive material is further characterized in that it has an ".ffpmedeleEluorid compatibility value" in the order of an EDA value of at least 40, preferably at about 70-120, n glow = "ast in the range 4- 6%, a (compact) - density in the range 0.24-0.5 in the range 70-95 cm 2/10 g and a BET surface area in the range 100-250 m2 / q gíml, an oil absorption (oil requirement) in with an average particle size in the order of 5-15 microns.

The tooth abrasives described here, when incorporated into a toothpaste, provide high fluoride compatibility and excellent cleaning effect. The definition of low structure silica material is found in the aforementioned U.S. Pat. No. 3,893,840.

The tooth grinding materials according to the invention consist of precipitated silica, which are produced by means of the general methods described in e.g. U.S. Pat. Nos. 3,893,840, 3,988,162 and 4,067,746, to which reference is thus made. Abrasives prepared by such methods are then treated with alkaline earth metal ions in the manner described herein. In general, the process for producing the silicas comprises acidifying an aqueous alkali metal silicate solution with a mineral acid to effect precipitation of silica. The addition of acid is continued until an acidic pH is reached, and the resulting precipitated silica is then removed with e.g. filtration and washed to remove any by-product materials, e.g. alkali metal sulphate, so that a wet filter cake is obtained. The resulting wet cake is then reslurried in its own water or with additional water and then treated with the required amount of alkaline earth metal ions in the form of a soluble salt, so as to obtain the abrasive materials of the invention.

The abrasive products according to the present application must be distinguished from the precipitated silica compositions, which have been treated with alkaline earth metal ions and which are described in Swedish patent application 7710024-6. The silicas described in this patent application, which have been treated with alkaline earth metals, constitute abrasives which are useful for incorporation into toothpaste compositions to prevent corrosion of uncoated aluminum toothpaste tubes. Such anti-corrosion precipitated silicas as described in the above-mentioned application constitute silicas, produced by means of a so-called sulfate solution method. In this method an electrolyte is mixed, which e.g. alkali metal sulphate, with the alkali metal silicate solution while acidifying with mineral acid as described e.g. in U.S. Patent Nos. 3,960,586 and 3,928,541. Although the products according to the above-mentioned Swedish patent application can be described as precipitated silicas, which are thoroughly mixed with a quantity of alkaline earth metal ions, which are within the same range as in connection with the present invention, the abrasive products according to the present invention have other characteristics than the silicas derived. from the sulphate solution method. The silica materials prepared by the sulphate solution method, when used in certain fluoride-containing toothpaste compositions, do not provide the same extremely good fluoride compatibility values as in the present invention. The extremely good fluoride compatibility values of the dentifrices of the present invention are achieved only with the silicas produced according to the so-called so-called the alkali metal silicate process using freshly prepared aqueous solution.

The silica abrasives according to the invention consist of alkaline earth metal-treated precipitated silica, which are prepared from freshly prepared silicate aqueous solutions. In such a process no electrolyte is used. like for example. sodium sulphate, in the preparation of the untreated precipitated silica. In the products according to the invention it has further been found that the presence of alkaline earth metal ions in intimate association with the obtained silica must occur within a very narrow range in order to achieve the fluoride compatibility necessary for use in connection with the invention. The abrasive products according to the invention thus have fluoride compatibility values of at least 90%, while the abrasives prepared according to Swedish patent application 7710024-6 generally give compatibility values of 89% or less when determined by the toothpaste fluoride compatibility tests described in this application.

One theory is that the improved fluoride compatibility of the topical abrasives in question is based on the manner in which the silanol groups therein are bonded to the surface of the silica product. In the silica derived from a freshly prepared silicate aqueous solution according to the invention, the silanol groups on the surface of the material are thus assumed to be more readily available than on the silica, which originates from sulphate solution silicate and which is described in Swedish patent application 7710024-6. The dioxides are also, depending on the corresponding acidity of the silica obtained by the sulphate solution process. Since eilanol grip material, does not turn out the inaebeenåe vt? particularly sensitive to calcium treatment achieves: luaria compatibility in sulphate solution products. The seeds according to the Swedish patent increase 7710024-6 also have a higher wear value than the silicas according to the present invention. Therefore, the abrasive mill in question must be distinguished from the silica-treated silicon dioxides of the type described in the above-mentioned Swedish patent application.

The present precipitated silica abrasives are conveniently prepared by introducing an aqueous alkali metal silicate solution, preferably a sodium silicate solution, into a reactant. The aqueous sodium silicate solution consists of a freshly prepared aqueous solution with a sodium silicate concentration range of about -17% by weight and in particular 12.5-in 5% by weight, and a sodium- for obtaining the best bJ, 5, like composition corresponding to Na 2 O. The temperature of the 2,6SiO solution is then satisfied _ -o ._, _ ._ u _ then to about 50-95 ° C and with continuous q amrurging the solubilization results are obtained. The aqueous sodium silica in the gene by the addition of an aqueous solution of a mineral acid having a concentration of about 10-20% by weight at a generally consistent pH in the range of from about 8.5 to 0.3. The mineral acid is preferably sulfuric acid, as sulfuric acid gives the best results, but as is known in the art (see U.S. Patents 3,988,162, 3,893,840 and 4,067,746, other acidulants, such as nitric acid, In this context, specific reference is made to the above-mentioned publications, which describe methods for producing silicas of the type treated here.

In the most preferred embodiment, only a portion of the alkali metal silicate solution is charged to the reactant vessel and after tempering with stirring, the sulfuric acid is added simultaneously but the remainder of the alkali metal silicate solution to the first charged silicate solution at the reaction temperature. Preferably, a fine 8 to 1% by weight of the metal silicate is charged to the reaction vessel from the beginning. The remaining proportion is then added together with the sulfuric acid. The period of time during which the alkali metal silicate and sulfuric acid are added to the alkali metal silicate in the reaction vessel can be determined in advance and based in general on the volume of the reaction vessel and the difficulties of controlling the temperature and stirring. After completion of the addition of the alkali metal silicate solution, the acidifying agent is added continuously, until the pH of the reaction slurry drops below about 6.0 and preferably to a value in the range of about 4.6-5.0. The resulting slurry consists of the precipitated silica existing in the reaction medium.

After the pH below 6.0 is reached, the slurry is heated for a period of digestion at a temperature of 10-3000 above the reaction temperature, and then the pH of the reaction mixture is again adjusted, if necessary. The resulting slurry is then filtered and washed with additional water to remove any by-products from the reaction, such as sodium sulphate, which may be present in the silica product. The moisture content of the obtained wet filter cake is in the range from about 60-66% and the material consists of a low structure material. The above-described reaction to this point is generally the same as described in the aforementioned U.S. Pat. Nos. 3,893,840, 3,988,162 and 4,067,746 in the production of kettle dioxide, prepared from freshly prepared aqueous solution of alkali metal silicate.

In the process according to the invention, the material at the point where filtration and washing of the wet silica cake has been carried out is then subjected to treatment with alkaline earth metal ions, so that the new abrasive products according to the invention are obtained. According to the method of the invention, the wet, washed filter cake is then resuspended in its own water or with the addition of fresh water at ambient temperature with stirring. During stirring, this slurry is then treated with sufficiently alkaline earth metal ions, preferably calcium ions, in the form of a salt which is sufficiently soluble to give a quantity of alkaline earth metal ions corresponding to 10-300 ppm (parts per million) or 0.001-0 .03% by weight (based on the weight of the dry, recoverable silica) alkaline earth metal ions, intimately combined with the silica.

The alkaline earth metal ion added in this step is preferably calcium ion due to its easy availability, low cost and ease of incorporation into the silica. The calcium ions can be incorporated into the silica at this stage in any sufficiently water-soluble form (ie soluble in water to an extent of at least 0.07 g / 100 μg H 2 O at 2UOC), e.g. . with solutions of calcium nitrate, calcium oxide, calcium hydroxide or calcium chloride.

Burnt lime or calcium hydroxide are preferred. In addition, solutions of organic salts, such as calcium acetate, calcium formate and similar compounds, used Corresponding strentium and magnesium salts of the alkaline earth metals can also be used. Salts, which are approved for food use, must be used.

After treatment with the alkaline earth metal ion, the slurry of the filter cake is stirred vigorously for 16-EG minutes, preferably 15 minutes, so as to obtain the effective level of alkaline earth metal for treatment on the surface of the silica abrasive. The product obtained is then dried. Preferably, the drying is carried out in a spray drying plant at an inlet temperature of 4 ° C and an outlet temperature of 122 ° C in a known manner, after which the product is ground to the desired degree of fineness.

Toothpastes The novel precipitated silica abrasives of the present invention are used in therapeutic toothpastes which, in addition to the abrasives in question, contain certain amounts of a water-soluble, fluoride-releasing material, a binder, a preservative and water. The following is a review of these additional components in the toothpastes as well as optional components in them: A. Abrasives As pointed out above, the present precipitated silica abrasives are particularly suitable for incorporation into fluoride-containing therapeutic toothpaste compositions. Therapeutic toothpastes, which utilize such abrasives, provide satisfactory cleaning of the teeth and also have excellent abrasive-fluoride compatibility properties. The actual toothpaste compositions contain substantially about 5 to 35% by weight, preferably about 10 to 20% by weight, of the precipitated silica abrasives described.

B. Fluoride Ion Raw Material The present therapeutic toothpaste compositions further contain about 0.01-3% by weight, preferably about 0.1-1.0% by weight, of a water-soluble, fluorine-containing material, which provides fluoride ions in aqueous solutions. Such fluoride ions combine with tooth enamel and reduce “ÜIQÜZ9Q1 - k 12 thus the solubility of the enamel in acid. Applying fluoride ions to tooth enamel provides protection against tooth decay.

A large number of different fluoride ion-releasing materials can be used as raw materials for obtaining soluble fluoride in the compositions in question. Examples of suitable fluoride ion-releasing materials are found in U.S. Patent Nos. 3,535,421 and 3,678,154, both of which are incorporated herein by reference. Examples of preferred fluoride ionic raw materials for use in this context are sodium fluoride (NaF), stannous fluoride (SnF2), potassium fluoride (KF), potassium stannofluoride (SnF2-KF), indium fluoride (InF3), zinc fluoride (ZnF1) and NH4 fluorine (ammonium chloride). (SnClF). Sodium fluoride and stannous fluoride are particularly preferred, as are mixtures thereof.

Preferably, the toothpaste compositions in question give about 50-500 ppm, in particular about 100-4Û0 ppm, flucrid ions in the aqueous solutions which are in contact with tooth surfaces when the tan paste is used in the mouth. As described in more detail below, such solutions are mimicked by preparing slurries of the actual toothpaste compositions in a weight ratio of water: water paste of 3: 1 and then centrifuging the slurries to obtain a clear aqueous solution. The fluoride ion concentration in such a clear, centrifuged solution is taken as a measure of the "soluble fluoride" content obtained from a given fluoride-containing toothpaste composition.

C. Binder In addition, an adhesive is used as an essential ingredient to prevent the separation of the liquid phase and the solid phase in the toothpaste compositions. Such binders are well known in the art of toothpaste. The most commonly used binder is the seaweed colloids, which e.g. carrageenan (so-called Irish moss or Viscarin (š>), and derivatives of cellulose, such as sodium carboxymethylcellulose and hydroxyethylcellulose. Another type of binder suitable for use in this context is rubber materials, such as 1) vegetable rubber materials, e.g. guar gum material and 2) fermentation products, e.g. xanthan gum. The binder component generally constitutes about 0.1-5% by weight, preferably 0.2-2% by weight, of the present toothpaste compositions.

Since the natural and synthetic aqueous dispersions of the water binders are subject to microbiological or mold infestation, the toothpastes may optionally contain a relatively small amount of a preservative. Examples of preservatives which are normally used are the esters of parahydroxyl benzoates. Toothpaste binders are described in more detail in U.S. Pat. Nos. 2,839,448 and 3,862,307, to which reference is thus made.

D. Moisturizer Another essential component of the described toothpaste compositions is a humectant. Suitable moisture-retaining materials are also those well known in the toothpaste technique. The purpose of the humectant is to retain moisture and thereby prevent the toothpaste compositions from hardening in contact with air. Certain humectants can also give the toothpaste compositions the desired density or aroma. The humectant generally constitutes about 5-55% by weight, preferably about 20-36% by weight of the present toothpaste compositions.

Examples of suitable humectants for use in connection with the invention are edible, polyhydric alcohols, such as e.g. glycerol, sorbitol, xylitol and propylene glycol. Sorbi ol was often used in the form of a 70-ounce aqueous solution, known as Sorboö. Mixtures of glycerol and sorbitol are especially preferred as the humectant component of the described toothpaste compositions.

E. Water Water is another essential ingredient in toothpastes with the abrasives according to the invention. Water used in the preparation of commercially suitable toothpastes must be softened and free from organic contaminants. Water constitutes from about 15 to 80% by weight, preferably about 15-40% by weight, of the toothpaste compositions.

F. Optional Ingredients In addition to the necessary components described above, the toothpastes described may contain a wide variety of optional, commonly used toothpaste components. These optional ingredients include (1) foaming enhancers, (2) dentifrice penetrants, (3) flavoring and sweetening agents, (4) tartar and plaque inhibitors, and (5) pigments and dyes. 1) Foaming enhancer An preferred optional ingredient is a suds enhancer.

Suitable foaming enhancers are those which are reasonably stable and form foams over a wide pH range, i.e. organic synthetic surfactants of the anionic types with the exception of soaps, nonionic, cationic, zwitterionic and amphoteric. . Foaming enhancers of these types are described in more detail in U.S. Pat. Nos. 3,959,455 and 3,937,807, to which both patents are incorporated herein by reference.

Examples of anionic foaming agents useful in this context are the water-soluble salts of alkyl sulfates having 8 to 18 carbon atoms in the alkyl radical and the water-soluble salts of sulfonated monoglycerides of fatty acids having 10 to 18 carbon atoms. Sodium lauryl sulfate and sodium coconut alkyl monoglyceride sulfonates are examples of anionic surfactants of this type. Mixtures of anionic surfactants can also be used.

The nonionic foaming agents which can be used in the present toothpastes can be generally defined as compounds which are prepared by condensation of alkylene oxide groups (hydrophilic in nature) with an organic, hydrophobic compound which may be aliphatic or alkylaromatic to its nature. Examples of suitable nonionic suds enhancers are the Pluronic surfactants, polyethylene oxide condensates of alkylphenols, products derived from the condensation of ethylene oxide with the reaction product between propylene oxide and ethylenediamine, ethylene oxide condensates, longitudinal aliphatic aliphatic, phosphine oxides, long chain dialkyl sulfoxides and mixtures of such materials.

The zwitterionic, synthetic, foaming agents useful in the described toothpastes can be generally described as derivatives of aliphatic, quaternary ammonium phosphonium and sulfonium compounds, wherein the aliphatic radicals may be straight or branched and wherein one of the aliphatic substituents contains from about 8-18 carbon atoms and one contains an anionic, water solubilizing group, e.g. a carboxy, sulfonate, sulfate, phosphate or phosphonate group.

The cationic, suds promoting agents useful in toothpastes with the abrasives of the invention can be generally defined as quaternary ammonium compounds having a long alkyl chain containing about 8 to about 18 carbon atoms, such as e.g. lauryl, 7602901 ~ lf cetylpyridiniunklorid, cetyltrimetvlammoniumh: omid, diisobutylfen- oxietoxietyl-dimethylbenzyl; ammonium chloride, kokosnötalkyltrimetylammo- niumnitrit, cetyfpyrídininmflosrid etc. Particularly preferred are the quaternary ammonium fluorides, as described in U.S. Patent No. 3,535,423, incorporated herein by reference Thus, the quaternary ammonium fluorides have their own purifying properties. The cationic, antifoaming agents may also function as the dental caries. a as germioids in some of the Amphoteric, antifoaming agents useful in the invention may be generally described as derivatives of aliphatic, sec. those and tertiary amines, wherein the aliphatic radical may be straight or branched and wherein one of the all-phase substituents contains from about 8 to about 18 carbon atoms and one contains an anionic, water-solubilizing group, for example a carboxylate, xylonate -, sulphate, phosphate or phosphonate group.

The foaming enhancing agent may be present in the toothpaste compositions in an amount of 0.1 ~ 6% by weight of the composition as a whole. 2) Phosphate Membrane Penetration Medal The toothpaste compositions contain as a highly preferred, optional component from about 5 to 12% by weight, preferably about 7-11% by weight, of a water-soluble "phosphate tooth penetration agent". The purpose of such soluble phosphates is to promote the transmission of fluoride ions through the naturally occurring thin saliva film, which is formed on the teeth. Fluoride-containing toothpastes, which utilize the levels of phosphates prescribed herein, show increased diffusion of fluoride through the salivary membrane of the teeth and increased fluoride uptake into the tooth enamel in comparison with fluoride-containing toothpastes which do not contain any such phosphate toothpaste penetrants.

Although relatively high levels of soluble phosphates can provide advantages in the penetration of fluoride through said salivary membrane into fluoride-containing toothpastes, the presence of such salts can also reduce the stability of the soluble fluoride in such toothpastes during storage. Surprisingly, however, it has been found that such soluble phosphates can be incorporated into the silica-containing, fluoride-containing toothpastes described herein with particularly favorable fluoride compatibility results, if the special silica-treated alkaline earth metal precipitates are precipitated according to silica abrasives. "WÛNM" Ä 16 ningen is used.

The phosphates optionally included in the toothpastes are water-soluble. In the context of the invention, a "water-soluble" phosphate means a phosphate which is soluble in water in an amount of at least 3.0 g / 100 cm 3 of H 2 O at 20 ° C.

Phosphates are the phosphorus compounds, where in the constituent anions each phosphorus atom is surrounded by four oxygen atoms, located in the corner of a tetrahedron. By dividing oxygen atoms between tetrahedra, chains, rings and branches, polymers of interconnected PO 4 tetrahedra can be realized. Simple phosphates are orthophosphates. Polymeric phosphates include the polyphosphates, such as the pyrophosphates and the tripolyphosphates.

Annular phosphate is the metaphosphate.

Examples of suitable water-soluble polyphosphates for use in the context of the invention include tetrachotassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate and potassium tripolyphosphate. Examples of suitable water-soluble metaphosphates include monopotassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate and sodium heptametaphosphate. Many of these water-soluble polyphosphates and metaphosphates are used in the form of hydrated salts.

The most suitable phosphates for use in connection with the invention are the simple orthophosphates. Orthophosphates are derived from tribasic orthophosphoric acid of the formula H3PO4. Water-soluble sodium, potassium and ammonium salts can be used.

There are about ten different crystalline sodium orthophosphates among the different hydrates. These include e.g. NaH2PO4, NaH2PO4 .H2O, NaH2PO4. 2H2O, Na2HPO4, Na2PO4.2H2O, Na2HPO4.7H2O, Na2HPO4.12H2O, Na3PO4.6H2O, Na3PO4.8H2O and mixtures thereof. Preferred sodium orthophosphates comprise NaH 2 PO 4 .H 2 are mixtures of NaH 2 PO 4 .H 2 O and Na 2 HPO 4 .2H 2 O in a weight. Particular ratio between monosodium salt and disodium salt in the range from about 1: 3 to 1: 5.

The potassium and ammonium orthophosphate can also be used as a dental membrane penetrant in connection with the invention. Examples of such potassium and ammonium salts are KHZPO4, KZHPO4, K2HPO4.2H2O, 'WOÉNÉ' iz- 1 <2H1 = o4.6n2ø, Kšjeoßßlazo, f: Pzig fi fnga,: äaolyaëæz-: n (aanl fl, HPO4, (NH4) 3PG4 and mixtures of these salts.

An especially preferred invention for use in toothbrushes containing the abrasive coma compounds of the invention comprises a mixture of NaH,? 0¿.H2C and K, HPü¿ in a weight ratio between sodium and potassium salt in the art. wn rwn na?: 3 to 1: 5.

The useful phosphates used in the present invention are a detailed description of such phosphates which are useful in connection with the invention, can be found in Kirk & Othmer, Encyclopedia of Chemical Technology, Second Edition, Volume 15, Interscience Publianers, Inc. . (1968), pp. 232-276, to which reference is made.

Preferably, the present toothpaste compositions give concentrations of about 0.5 mol / 1000 g H26 to 2.0 g mol / 1000 g H 2 O phosphates in the aqueous solutions which are in contact with the tooth surfaces when the toothpastes according to the invention are used in the oral cavity. Here, too, the clear solution obtained after centrifugation of 3: 1 slurries of water and toothpaste was used to mimic such use solutions.

In addition, additional dental perforation permeability can optionally be added to the fluoride-containing tan pastes. Such optional ingredients further increase the beneficial properties obtained by the phosphates in terms of the ability of the fluorides to penetrate the salivary membrane of the teeth. Such means include e.g. hydroxyl groups and salts thereof, such as e.g. citric acid, trinatrin citrate, malic acid and tartaric acid.

If such extra denture penetrants are included, they comprise about 0.2-5.0% by weight of the toothpaste composition. å) Flavoring agent Flavoring agents can also be added to the compositions in question. Suitable flavoring agents include oil from evergreens, peppermint oil, oil from garden mint, sassafras oil and clove oil. Sweetening agents that can be used include saccharin, dextrose, levulose, aspartame, D-tryptophan, acetosulfame, dihydrochalkones and sodium cyclamate. Flavoring agents are generally used in toothpastes at concentrations of about 0.01 to 2% by weight and sweeteners at concentrations of about 0.05 to about 3% by weight. ? 8®29Üis4 18 4) Plaque / tartar inhibitors Phosphorus-containing tartar-preventing agents and / or bis-biguanide-based, plaque-preventing agents can also be optionally added to the toothpastes. Phosphorus-containing tartar inhibitors, such as Disodium methane-1-hydroxy-1,1-diphosphonate and closely related materials are described in more detail in U.S. Pat. No. 3,488,419, which is incorporated herein by reference. Plaque-preventing bis-biguanide agents, such as chlorhexidine (1,6-bis [N5-p-chlorophenyl-N1-biguaniaxane, ae soluble ash The soluble salts thereof and closely related materials, eg 1,2-bis (N5-p-trifluoromethylphenylN1-biguanido), are described in more detail in U.S. Pat. Nos. 3,934,002 and 3,937,807 and in Belgian Pat. Nos. 843,244 and 844,764, to which patents are referred herein.

In cases where the optional tartar preventing and / or plaque preventing agents are used, they generally comprise from about 0.01 to 2.5% by weight of the toothpaste compositions of the invention.

) Pigments and dyes, other constituents A large number of other optional components, which are well known in the art, can be added to the toothpaste compositions with the abrasives of the invention to improve their usual aesthetic properties. These include pigments, dyes, marbles and similar materials. When these optional components are used, they generally comprise from about 0.001% to about 2% by weight of the toothpastes.

Preparation of toothpaste compositions Toothpaste compositions containing abrasives according to the invention are prepared by simply mixing the necessary and optional components in any order and in any conventional manner, as described in more detail above. Once the compositions are prepared, they give a pH of about 4.0-8.0, preferably 6.5-7.5, when the compositions are slurried with water in a 3: 1 weight ratio of water to composition. Fluoride-containing toothpastes, which give pH values in the range 4.0-8.0, give particularly effective results in terms of counteracting the solubility of tooth enamel compared with toothpastes with pH values outside this range. The flavoring of toothpastes within this pH range is also comparatively simple.

Use of toothpaste compositions The obtained toothpaste compositions are used in a conventional manner. 1ao29ø1-4 19 The toothpaste compositions or their slurries are brushed on the tooth surfaces and then rinsed off.

When using the described toothpastes in a conventional manner, the pastes according to the slurries are generally in contact with the tooth surfaces for at least about 30 seconds. Preferably, such pastes or slurries are in contact with the tooth surfaces for at least about 60 seconds.

The following examples are intended to further illustrate the invention, which, however, should not be construed as being limited thereto. In the examples below, parts refer to "parts by weight", unless otherwise specified.

Example 1 In a 30,000 l stainless steel reaction vessel, jacketed for steam heating, 1794 l of sodium silicate solution (3.78% Na 2 O, 9.53% SiO 2) with a density of 1.121 and containing 42 g Na 2 O per liter were added.

The reaction medium was heated to 88 ° C with continuous stirring. At this time, sulfuric acid with a concentration of 10% (density 1.066) and sodium silicate solution were added simultaneously to the reaction medium at a rate of 151.4 l / min. acid and 351 l / min. sodium silicate, while maintaining the reaction temperature at 8800 3 1 ° C. These two solutions were added to the reaction medium over a predetermined period of time. The addition of the silicate solution was stopped after 47 minutes, but the addition of acid was continued until the pH of the slurry was between 4.8 and 5.0. The reaction slurry was boiled at 100 ° C for minutes, and the pH of the reaction mixture was readjusted to a value between 4.8 and 5.0. The resulting silica slurry was filtered and washed to remove most of the by-products formed in the reaction (sodium sulfate), after which the filter cake was dried and the dry product was ground to the desired degree of fineness. The dry silica was subjected to various physicochemical tests and the results are shown below (see Table I). This example relates to the preparation of a reference product to which no alkaline earth metal was added.

Example 2 To a 30,000 l stainless steel reaction vessel, jacketed for steam heating, was charged 1794 l of sodium silicate solution (3.78% Na 2 O, 9.53 SiO 2) having a density of 1.121 and containing 42 g of Na 2 O per liter.

In this step of the preparation, sulfuric acid with a concentration of 10% (density 1.066) and sodium silicate solution were added simultaneously to the reaction medium at the rate of 151.4 l / min. acid and 351 l / min. sodium silicate, while maintaining the reaction temperature at 88 ° C for 1 ° C. These two solutions are added to the reaction medium over a predetermined period of time. The addition of the silicate solution was stopped after 47 minutes, but the addition of the acid was continued until the pH of the slurry was between 4.8 and 5.0. The reaction slurry was boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was again adjusted to a value between 4.8 and 5.0. The resulting silica slurry was filtered and washed to remove most of the by-products formed in the reaction (sodium sulfate).

The washed filter cake was then reslurried without any addition of water at ambient temperature or while stirring. While stirring the slurry, it was treated with 102 g of calcium hydroxide of a grade approved for food use to obtain a calcium ion treatment of 25 ppm, based on the total weight of dry recoverable solid product in the slurry. After treatment with the calcium ions, it was stirred. of the slurry cake obtained by the filter cake vigorously for 15 minutes, so that the effective level of calcium ion treatment on the surface of the silica abrasive was obtained. The resulting product was then spray dried at an inlet temperature of 48306 and an outlet temperature of 122 ° C, ground and tested for abrasion and other physical properties in the same manner as with the abrasive of Example 1.

Example 3 The method in this example was the same as in Example 2 except for the rate of addition of sulfuric acid, which was 162.7 l / min. and the calcium addition amounting to 204 g of calcium hydroxide to give 50 ppm of calcium ion. After preparation, this product was also analyzed.

Example 4 In this example, the procedure was the same as in Example 2, except that the rate of addition of sulfuric acid was 166.5 l / min. and the calcium addition was 408 g of calcium hydroxide to give 100 ppm of calcium ion in the silica. After completion of the land, the product was then analyzed.

Example 5 In this example, a silica abrasive was prepared for toothpaste 780290141 a .. 71 by initially adding 1420 l of sodium silicate solution (4.09% Na 2 O, 10.31% SiO 2) having a density of 1.131 and containing 46.3 g of Na 2 O per liter to the reaction vessel as a reaction medium. The reaction vessel was heated to 91 ° C with continuous stirring. In this step of the preparation, sulfuric acid with a concentration of 12% (density 1.08) and sodium silicate solution were added simultaneously to the reaction medium at the rates of 162.7 l / min. acid and 315.7 l / min, sodium silicate, while maintaining the reaction temperature at 91 ° C.

The addition of the silicate solution was stopped after 47 minutes, but the addition of the acid was continued until the pH of the slurry was between 4.6 and 4.8. The reaction slurry was boiled at 100 ° C for 20 minutes and then the arrow value of the reaction mixture was again adjusted to a value between 4.6 and 4.8. The resulting silica slurry was filtered and washed to remove the by-product sodium sulfate.

The washed filter cake was then resuspended without the addition of water at ambient temperature and with stirring. While stirring the slurry, it was treated with 510 g of calcium hydroxide of a grade approved for food use to obtain a cation treatment of 125 ppm based on the total weight of the dry, recoverable slurry. silica abrasive. After treatment with the calcium ion material, the slurry obtained from the cake was stirred vigorously for 15 minutes to obtain the effective degree of calcium ion treatment on the surface of the silica abrasive. The resulting product was then spray dried at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C, after which it was ground and analyzed.

Example Gel 6 Example 5 was repeated except that 1608 l of sodium silicate solution were initially charged to the reaction vessel as a reaction medium and that the rate of acid addition was increased to 170.3 l / min, while thereafter the rate of addition of the silicate solution was maintained. at 315.7 l / min.

The washed filter cake was treated with 816 g of calcium hydroxide to provide 200 ppm of calcium ion treatment on the surface of the silica gel. After completion, the product was then analyzed. Example 7 I This example was carried out in the same manner as Example 2 except that the addition of the calcium ion material consisted of 2040 g of calcium hydroxide to give 500 ppm of calcium ions. This product was also analyzed after completion.

After preparation of the products of Examples 1-7, these were analyzed to determine certain physical properties and the results obtained are shown in the following Table I.

Table I% glow- _ Oil ab- **) BEE ~ Surface 'Particle size, Ex. nings- *) Density so tion ar ***) average value ****) no. loss (g / ml) (cm / 100 μl (nl / 9) (μm) 1 5.0 0.35 94 151 7.7 2 4.4 0.43 89 234 8.6 3 5.5 0.40 90 227 7.8 4 4.9 0.41 91 192 7.9 6.0 0.47 85 215 11.0 6 5.4 0.50 78 201 14.5 7 5.1 0.32 95 172 7 , 6 *) Water loss when a pre-dried silica abrasive was heated from 1os ° c to 90 ° C **) 4 Determination of oil absorption (oil demand), ASTM D281-31 ***) J. Am. Chem. Soc. §Q, 309-319 (1938) ****) Measured with the instrument Coulter Counter Model TA II.

Some representative toothpastes according to the invention are described in the following examples, in which the actual precipitated silica abrasives are used.

Example 8 Using the precipitated silica abrasive of Example 2, a toothpaste having the following composition was prepared: 780290141 23 Amount of precipitated silica abrasive (from Example 2) 15.0 Sodium fluoride (NaF) 0.28 Sorbitol solution (70%) 32.0 Glycerol 13 .0 Sodium carrageenan 0.75 Monosodium orthophosphate monohydrate (NaH2PO4 .H2O) 2.15 Disodium orthophosphate dihydrate (Naznpotrino) 3.34 Sodium alkyl sulphate solution (28.8%) 6.0 Coconut alkyl monoglyceride sodium sulphonate 0,2 Smacam Dye ("FD & G Blue No. 1", solution 1%) 0.35 Titanium dioxide (TiO2) 0.5 Trisodium citrate dihydrate (c6H5Na3oT2H2O) 0.25 Dist. Water residue to 100th 100.0 The toothpaste composition specified above The water component was first added to a suitable container, to which the toothpaste penetrants, the flavoring agent, were then added one after the other with moderate stirring. the humectant and then the remaining components.

A slurry of the above-described composition in freshly prepared form with water in the weight ratio of 3: 1 (3: 1 indicates water to composition) gave a pH of about 7.1.

Such a toothpaste composition provided advantageous fluoride treatment for dental tissue, which was thereby brushed due to the high toothpaste fluoride compatibility. The toothpaste also gave a good cleaning effect and an RDA value of 100. When stored for a long time at 27 ° C, such a toothpaste showed minimal loss of soluble fluoride.

Toothpastes which gave essentially the same benefits in terms of fluoride treatment, toothpaste-fluoride composition and cleaning effect were obtained when the sodium fluoride in the composition of Example 8 was replaced with an equivalent amount of stannous fluoride, sodium chlorofluoride, potassium fluorofluoride, potassium fluorofluoride, potassium fluoride, zinc fluoride or ammonium fluoride.

Toothpastes, which gave essentially the same benefits in terms of fluoride treatment and essentially similar cleaning results, were also obtained when the phosphate mixture in the composition according to Example 8 was replaced with an equivalent amount of NaH 2 PO 4, NaH 2 PO 4 .H 2 O, NaH 2 PO 4, 2H 2 O, Na 2 H 2 P 2 , Na31> o4.6z12o, Naforsazo, KHZPOLI, Kznpoll, Kznmyznzo, KZHPOÅVGHZO, 1 <3Po4.3r12o, K3Po4JJ2o, K3Po4.9f12o, (NH4) H2PO4, (NH4, NH4) 2HPO4 and Na 2 HPO 4 .2H 2 O in weight ratios of monosodium salt to disodium salt between about 1: 3 and 1: 5, mixtures of NaH 2 PO 4 .H 2 O and K 2 HPO 4. 2H2O in the weight ratio of sodium salt to potassium salt of between about 1: 3 and 1: 5, tetracalial pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium methamphetaphthate phosphate monocarbon value of 4.0-8.0 in a 3: 1 slurry.

Example Gel 9 A toothpaste with a high abrasive effect was formulated using the precipitated silica abrasive of Example 3, the toothpaste having the following composition: Amount Component (weight Precipitated silica abrasive (from Example 3) 35.0 Sodium fluoride (NaF) 0.22 Glycerol solution 5 (70%) 20.0 Carboxymethylcellulose (degree of substitution 0.7) 0.5 Magnesium aluminum silicate ("Veegum" flakes) 0.3 Monosodium orthophosphate monohydrate (NaH2PO4 .H2O) 0.3 Disodium orthophosphate dihydrate (Na2meo4. (28 | 8%) 2: 3 Coconut alkyl monoglyceride sodium sulfonate 0.7 Flavor 0 'Sodium saccharin of 0,5 Titanium dioxide (TiO 2) 7802901 - 4 Amount Component (weight%) Marbling agent 0,5 Dest. Water residue to 100 Sza 100,0 Toothpaste , which provided substantially the same benefits in terms of fluoride treatment, toothpaste-fluoride compatibility and cleaning effect, was obtained when the precipitated silica abrasive component of Example 3 in the composition of Example 9 was replaced by an equivalent amount of abrasive, prepared according to Examples 2, 4, 5 and 6.

Toothpaste, which provided substantially the same benefits in terms of fluoride treatment and substantially the same cleaning effect, was obtained when the phosphate mixture in the composition of Example 9 was replaced with an equivalent amount of NaH 2 PO 4, NaH 2 PO 4 .H 2 O, NaH 2 PO 4 .2H 2 O, Na 2 HPO 4, Na 2 Na 2 , Na3Po4.6H2o, Na3Po4.sH2o, KHZPOU K2HPo4, K2HPo4.2H2o, Knxporsnzo, 1 <3Po4.3rx2o, K3Po4.7n2o, 1¿3Po4.9n2o, (NH4) H2Po4, (NH4) , other mixtures of NaH2PO4 .H2O and Na2HPO4.2H2O in weight ratios of the monosodium salt to the disodium salt of about 1: 3 to 1: 5, mixtures of NaH2PO4 .H2O and K2HPO4.2H2O in weight ratios of the sodium salt to the potassium salt of between about 1: 3 and 1: 5, tetra potassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, monopotassium metaphosphate, sodium trimetaphosphate, sodium hexamaphaphth slurry.

Example 10 Using the precipitated silica abrasive of Example 4, a clear toothpaste was prepared which had the following composition: Amount of component (Weight *%) Precipitated silica abrasive (from Example 4) 20.0 Sodium fluoride (NaF) 0.24 Sorbitol solution (70%) 57.0 Glycerol 1510 Sodium carrageenan 0.5 Phosphoric acid (85%) 0.10 Sodium alkyl sulphate solution (28.8%) 4.0? 8 ^ 02901-1 | 26 Quantity Component (weight_%) Flavor 1.0 Sodium saccharin 0.2 Dye ("FD & C Blue No. 1" solution, 1%) 0.05 Dest. Water left to 100 Sza 100.0 Example gel 11 Using the precipitated silica abrasive from Example 3 prepared a toothpaste with a low abrasive effect, which had the following composition: Amount Component (% by weight) Precipitated silica abrasive (from Example 3) 6.0 Stannofluoride (SnF2) 0.40 Sorbitol solution (70%) 51.0 Glycerol 25.6 Sodium carboxymethylcellulose (degree of substitution 0.7) 1.0 Sorbitan monoisostearate 2.00 Sodium alkyl sulphate solution (28.8%) 6.0 Flavor 1.20 Sodium saccharin 0.28 Dye ("FD & C Blue No. 1 "~ solution, 1%) 0.25 Fire, colloidal silica (uxerosil zoov") *) 5.00 Dest. Water residue to 100 Sza 100.0 *) Marketed by Degusta, Inc.

Toothpaste, which provided substantially the same benefits in terms of fluoride treatment, toothpaste-fluoride compatibility and cleaning effect, was realized when the precipitated silica abrasive component of Example 4 in the composition of Example 10 was replaced with an equivalent amount of abrasive prepared according to Example 2. 3, 5 and 6.

A toothpaste which gave substantially the same benefits in terms of fluoride treatment and an improved tartar-preventing effect was realized when the composition of Example 10 additionally contained about 1.0% by weight of disodium ethane-1-hydroxy-1,1-diphosphonate. Test and Evaluation The precipitated silica abrasives described herein can be used to prepare particularly suitable therapeutic toothpaste compositions containing soluble phosphate dentifrices. Such compositions provide both high abrasive fluoride compatibility and yet good tooth cleaning effect. The tests and evaluations presented below are intended to demonstrate the excellent fluoride compatibility achieved by the precipitated silica dentifrices in the toothpaste compositions of the invention described herein.

It is also shown below that abrasives of the present invention provide higher abrasive fluoride compatibility than similarly prepared abrasives which have not been treated to contain the substantial amounts of alkaline earth metal material. The excellent cleaning effect of the toothpaste compositions according to the invention is further demonstrated. Finally, it is also shown that abrasives made on the basis of a sulphate leaching process, even though they contain an alkaline earth metal material, are incapable of giving the high fluoride compatibility values obtained with the precipitated silica abrasives of the invention.

Abrasive-fluoride compatibility Precipitated silica abrasives can be classified for their relative compatibility with fluoride materials using a 24-hour abrasive slurry test. Such a sample can be used to obtain data, by means of which one can predict the availability of soluble fluoride in certain types of fluoride-containing toothpastes after storage for about a 4-week period at 27 ° C. The 24 hour abrasive slurry sample was used to obtain fluoride compatibility values, which are defined as the percentage of theoretically maximum available fluoride that is actually measured after 24 hours as soluble fluoride using the following test method.

This method ("Orion Specific Ion Electrode Method") prepares a standard sodium fluoride starting solution containing 1624 ppm fluoride by dissolving 2.8 g of sodium fluoride, 21.5 g of NaH 2 PO 4 and 83.4 g of Na 2 HPO 4 .2H 2 O in 672.5 g of deionized distilled water and then store this solution in a polyethylene bottle. 30 g of this solution are then weighed. 7 g of the silica abrasive to be applied. is then dispersed in the solution and allowed to stand in contact with it for 24 hours at a temperature of about 37.8 ° C. After 24 hours, the solution of precipitated silica abrasive / fluoride is centrifuged for 20 minutes at 000 rpm or until the above solution is clear.

Then pipette 10 ml of the clear solution into a plastic ampoule.

Then pipette the plastic ampoule with 10 ml of EDTA / THAM solution. (EDTA / THAM solution is a 0.2 molar solution of EDTA (ethylenediaminetetraacetic acid, disodium salt) and 0.2 molar of THAM (2-smino-2-hydroxymethyl-1,2-propanediol which is adjusted to pH = 8.0 with sodium hydroxide.) A magnetic stirrer is stopped and gentle stirring is started.The fluoride ion concentration is determined by direct potentiometric measurement using the Orion fluoride electrode ("Model 95-09"). Emf is converted to parts per million (ppm) of fluoride in the above clear solution using a logarithmic equation, the fluoride compatibility value is then calculated by expressing the measured amount of soluble fluoride in ppm as a percentage of the theoretically available soluble fluoride.

Using this method, the relative abrasive fluoride-I compatibility values for all the abrasives prepared in accordance with Examples 1-7 were determined. The results of this determination are shown in Table II below.

Table II Abrasives-fluoride compatibility Calcium- Abrasives- Example _ treatment -fluoride- no. . (ppm) compatibility 1 (reference test) 0 76% 2 25 93% 3 50 94% 4 r 100 93% 125 91% 6 200 90% 7 500 88% It appears from the values in Table II that the precipitated silica abrasives according to the invention contain special amounts of an alkaline earth metal material gave significantly better abrasive fluoride compatibility compared to that obtained with a material which did not contain any alkaline earth metal but which was otherwise produced in a similar manner. Precipitated silica abrasives, which are prepared in the manner set forth in Examples 2-6, should thus be suitable for providing fluoride toothpastes and dentifrice penetrants which exhibit high abrasive fluoride compatibility.

Abrasive Fluoride Compatibility in Toothpastes Preferred toothpastes containing precipitated silica abrasives and dentifrice penetrants according to the invention were evaluated for their abrasive fluoride compatibility. The toothpastes prepared for the evaluation had the same composition as the toothpaste in Example 8 and varied only in terms of the abrasive component.

To determine fluoride compatibility values for the tested toothpastes, a soluble fluoride determination method was used, which was similar to the method described above for determining abrasive fluoride compatibility values. In this method, the toothpaste compositions are stored for a certain time in a laminate tube. Then 15.0 g of the composition is transferred to a 100 ml beaker and then 45.0 g of distilled water are added. The mixture is then stirred to obtain a slurry in which the toothpaste is evenly dispersed. The slurry is then centrifuged for 20 minutes at a speed of 15,009 or until the above solution is ready.

The clear solution is then treated as in the above-described method for determining abrasive fluoride compatibility. The soluble fluoride concentration is similarly measured and an abrasive fluoride compatibility value is also calculated for each toothpaste. The obtained toothpaste-fluoride compatibility values of the respective toothpastes were determined and compiled in Table III below. The abrasives tested are the abrasives described in Examples 1-7 above and characterized in Table I.

Table III Toothpaste-fluoride compatibility Abrasives Toothpaste-fluoride- Example Calcium treatment -compatibility year no,) (ppm) (1 week - 27 C) 1 (reference sample) 0 76% 2 25 99% 3 so 98% 4 100 99% 125 97 % 780290144 Table III, cont.

Abrasives Toothpaste-fluoride- Example Calcium treatment -compatibility no.) (Ppm) (1 week - 27 ° C) 6 200 94% 7 500 90% It appears from the values in Table III that the preferred toothpastes, which use the precipitated silica abrasives according to the invention, gives superior abrasive fluoride compatibility values compared to those obtained with a similar toothpaste composition, containing the abrasives prepared by the method of Example 1 and which did not contain any alkaline earth metal. the values in Table III further show that the availability of soluble fluoride from the fluoride ion-releasing material is not significantly reduced during storage when the silica abrasives of the invention are used in the preferred toothpastes described herein.

Of course, however, it must be reckoned with that the amount of available soluble fluoride decreases to some extent also in the toothpaste compositions with the abrasives according to the invention as a function of increasing storage time and temperature during storage. Thus, toothpaste fluoride compatibility values for toothpastes stored for extended periods or under milder temperature conditions are generally lower than for the toothpastes exemplified above.

Additional abrasive fluoride compatibility values for a variety of toothpastes, which show storage for longer periods and higher temperatures, are found in Table IV below. vso2901-4 Tabe 3.1 gl 'Toothpaste-fluoride compatibility (Elevated temperature / prolonged storage) Toothpaste-fluoride compatibility Abrasive Calcium ~ (Example treatment 1 Xecka 1 Xecka 4 months 5 months no.) (ppm) 27 C 49 C 2 / C 27 C 1 0 76% 64% - 64% 2 25 99% 97% 91% - 3 50 98% 96% 91% - 4 100 99% 95% 91% - 125 97% 92% - - 6 200 94% 90% - - 7,500 90% 86% - 89% The values in Table IV show that the preferred toothpastes maintain their relatively high fluoride abrasive compatibility levels even during prolonged storage or under harsh storage conditions.

Cleaning effect The ability of the silica abrasives described to clean the teeth can be determined by means of a method for determining the wear of radioactive tooth substance and is stated in the form of so-called RDA values (RDA = "Radioactive Dentin Abrasion"). RDA values can be used to determine the relative cleaning ability of different abrasives for any given type of toothpaste abrasive. Thus, precipitated silica abrasives require an RDA value (measured with the one below). described method) of at least 40, preferably between 70 and 120, to ensure that the abrasive has sufficient abrasive capacity to be an effective toothpaste cleaner.Previously described precipitated silica abrasives which exhibit high toothpaste fluoride compatibility are in generally poor cleaning agents for dental hygiene purposes, as evidenced by the low RDA values, however, the abrasives treated with alkaline earth metal provide both effective tooth cleaning and high fluoride compatibility.

Several commercially available precipitated silica abrasives, which show relatively high toothpaste-fluoride compatibility, measured by the method described herein, were selected for evaluation of the RDA values.

The test was performed with a standard toothpaste base material having the same composition as the toothpaste of Example 8, which was changed only by varying the abrasive component.

The method used to determine the RDA values for toothpastes, which are compiled in Table V below, is described below. This test method is described in more detail in the Journal of Dental Research, July-August 1976, by Hefferen, pp. 563-573. The various steps in determining RDA values are shown in the following review: A. Selection and preparation of teeth Healthy, permanent teeth with a single root, which on extraction proved to be caries-free and vital, were selected. These tanks were then scraped clean with a scalpel. The crown and root tip of each tooth were removed using a grinding wheel to prepare a tooth sample, which was 14 mm long and at least 2 mm wide at the narrower end. Cut pieces of the root (tooth chips) or alternatively another tooth were also prepared for later use in determining a correction factor for self-absorption of radiation.

B. Irradiation of tooth substance The root parts and tooth substance chips processed according to step A were exposed to a neutron flux of 2 x 10 neutrons / cm2 for 3 hours.

C. Assembly of Root Parts After irradiation, the irradiated root parts were embedded in a bed of cold-curing methacrylate resin for dental purposes and then mounted in a transverse brushing machine. The toothbrushes used throughout the experiment were medium-hard, flat brushes made by "Pepsodent" with 50 straws in each bundle.

D. Pre-treatment of the tooth surfaces Before starting the test, the newly assembled, irradiated root parts were brushed with a reference slurry (10 g calcium pyrophosphate + 50 ml of a 0.5% CMC-10% glycerol solution) with 6000 strokes with the brush. At the start of the test in the following days, the root parts were brushed for 1000 days.

E. Test Procedure After pretreatment, the dental specimen samples were then conditioned with the reference slurry (same slurry as in step D) with 1500 strokes with the brush at the beginning and end of each test as well as 7802901 -4 33 during the test itself. The test itself consisted of brushing the tooth substance samples with 1500 strokes with the brush with a slurry of the test product (25 g toothpaste + 40 ml deionized distilled water).

F. Determination of correction factors The correction factors were determined by dissolving the tooth substance chips or alternatively another tooth from step B in 5 ml conc.

HCl and diluted with distilled water to a volume of 250 ml. 1 ml of this solution was added to sample pastes and reference slurries, which were prepared in a similar manner to those in step E, and then neutralized with 0.1 N NaOH.

Measurement of radioactive tracer The radioactivity of the slurry sample (1.0 ml) was determined with a liquid scintillation counter of the type "Intertechnique SL-30 liquid scintillation counter". Alternatively, the following can be done as follows: 3 ml portions of each of the slurries are transferred to flat-bottomed 25.4 mm x 7.9 mm stainless steel plates and measured using a Nuclear Chicago geiger counter system. Geiger Counting System ".

Calculations The RDA value for a particular paste corresponds to the ratio between the corrected average heart rate for this paste and the average heart rate for the reference sample multiplied by 100. The reference abrasive is set to an arbitrary RDA value of 100 units.

The results of such determinations of the RDA value are given in Table V.

Table §Qè: values Toothpaste-fluoride-compa- Abrasive Rai value tibility 11 week, 270m A. (Example no.) 1 Comparative test 75 in 76% 2 ao in 21 99% 3 of ï 98% 4 so in 99% s 103 is 97% 6 111 i'- s 94% 7 se I * - 4 90% 7302901-Å 34 Table V, cont.

Toothpaste-fluoride compat- Abrasive RDA value tability (1 week, 27 ° C) B. Commercial, precipitated silica products s "siaent 3" 1) 14 ï 2 92% 9 * Neosyv 2) 25 2 72% "Quso e- so "3) 22 i 2 87% 11" Neosyl ET "4) 25 f 4 84% 1) A precipitated silica from Degussa, Inc., (New York) 2) A precipitated silica from Joseph Crosfield a Sons, Ltd., (London, England) 3) A precipitated silica from Philadelphia Quarts Co., (Valley Forge, Pa.) 4) A precipitated silica from Joseph Crosfield & Sons, Ltd ,.

The results compiled in Table V show that commercially available precipitated silica abrasives may well show high abrasive fluoride compatibility but that they do not have a high enough abrasive effect to be useful as toothpaste abrasives. Surprisingly, the new precipitated silica abrasives according to the invention provide extremely good abrasive fluoride compatibility and this at the same time as they provide excellent RDA abrasion values, which values can be used as an indicator of the relative tooth cleaning ability.

Comparison between aliphens prepared according to the "fresh water solution method" according to the invention and the previously known "sulphate solution method" As emphasized above, the abrasive products according to the present invention are closely related to but clearly different from the calcium-treated silicas according to Swedish patent application 7710024-6. In order to illustrate this difference, the following attempts were made to compare the fluoride compatibility of the products according to the above application with that of the abrasive products according to the invention. using the following method: Dry sodium sulfate was added to 37.85 liters of water in a 750 liter reaction vessel, so that the sodium sulfate concentration in the reaction medium was 10%, the pH of the reaction medium was then adjusted to 9.0 The reaction temperature was 65 [deg.] C. The sodium silicate solution had a SiO2 / Na2O molar ratio of 2.5 and a concentration of 240 g / l. The reactant was added with sodium silicate for 4 minutes. a concentration of 11.4% was added to the reaction the forge, until the pH reaches 9.0.

Then the sodium silicate solution and the sulfuric acid solution were added simultaneously for a period of 35 minutes. After this 35-minute period of silicate addition was completed, the silicate addition was stopped and the acid addition continued until a slurry having a pH of 5.5 was obtained. The whole reaction mixture was digested at 77 ° C and the resulting wet cake was recovered and washed.

The wet cake was then treated in the manner described in Example 2 above, divided into six separate portions and these were treated with 50, 100, 200, 400 and 400, respectively. 800 ppm calcium from aqueous solutions of calcium hydroxide. Each of the wet cakes was then dried and processed in the manner described in Example 2 above and is finally characterized in Table VI below, where the first abrasive is a reference sample to which no calcium was added. The results obtained in the experiments are shown in Table VI.

Table VI "Sulphate solution" - Ca additive Abrasive-fluoride abrasive (ppm) compatibility *) A 0 (ref. Sample) 88 50 89 C 100 88 D 200 88 E 400 86 F 800 82 *) Determined with the associated The test method described in Table II As can be seen from the values in Table VI above, the calcium-treated "sulphate solution" abrasives according to Swedish patent application 7710024-6 gave abrasive fluoride compatibility values, which were generally lower than those obtained with the silica abrasives according to the invention, which 7802901- 4 36 produced according to the so-called Furthermore, the addition of an alkaline earth metal to abrasives prepared by the "sulfate solution method" does not result in any dramatic improvement in the abrasive fluoride compatibility, as shown in a comparison with Table II. in contrast, the addition of equivalent amounts of alkaline earth metal to the silica abrasives of the invention, which have been produced by the "fresh water solution method" in dramatic improvements in abrasive fluoride compatibility.

Claims (15)

10 15 20 25 30 7802901 ~ lr 3 "? Eatentkrav Abrasive composition, characterized in that it consists essentially of a precipitated, amorphous silica, prepared by charging at least a part of the alkali metal silicate used in freshly prepared aqueous solution to a reaction vessel and acidifying with a mineral acid, optionally simultaneously with the remaining proportion of the silicate solution, which silica intimately reacted with a salt of an alkaline earth metal to contain 10 - 300 ppm alkaline earth metal ions in the amorphous silica having an RDA value of at least 40, a (compact) density of 0, 24 - 0.55 g / ml, an oil absorption of 70 ~ 95 cmg / 100 g, a BET surface area of 100 - 250 m2 / g and an annealing loss of 4 - 6%. 2. An abrasive composition according to claim 1, characterized in that the alkaline earth metal ions are calcium, strontium or magnesium. Abrasive composition according to claim 1, characterized in that the constituent amount of alkaline earth metal ion is in the range 10 - 100 ppm. 4. An abrasive composition according to claim 1, characterized in that the alkaline earth metal consists of calcium ion. Abrasive composition according to claim 1, characterized in that the abrasive is prepared by preparing an amorphous silica by precipitation via acidification of a fresh-water-alkali metal silicate solution with a mineral acid, isolating a wet cake of the precipitated product and reacting it. wet the cake with a solution of a salt of the alkaline earth metal. Abrasive composition according to claim 5, characterized in that the mineral acid consists of sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid or carbonic acid. 7802901 - 4 10 15 20 25 30 35 33 Abrasive composition according to claim 6, characterized in that it is prepared by initially depositing only a part of the alkali metal silicate in the reaction vessel, the remaining part of the alkali metal silicate solution being added simultaneously with the mineral acid and the addition of the silicate solution being stopped after a predetermined time and wherein the mineral acid is added to a pH below 6.0 and the wet filter cake is isolated by filtration and washing. Abrasive composition according to claim 7, characterized in that the alkaline earth metal ion consists of calcium and is added in the form of a solution of a salt selected from a group consisting of calcium hydroxide, calcium oxide, calcium nitrate and calcium chloride. A process for preparing an abrasive composition according to claim 1, characterized in that an aqueous solution of an alkali metal silicate having a SiO 2 / X 2 O molar ratio of 2.0 to 2.7, wherein X represents alkali metal, is formed at a reaction temperature in the range from 77 ° C to 91 ° C, charging at least a portion of the silicate solution to a reaction vessel and acidifying with a mineral acid, optionally simultaneously with the remaining portion of the silicate solution, until the precipitate of silica is substantially complete, then continuing with the addition of mineral acid until the pH is 6.0 or less, digesting at a temperature 10 to 30 ° C higher than the reaction temperature for a period of 10 to 30 minutes, filtering the resulting slurry and washing the solid. the product with fresh water, resuspend the resulting wet cake in water and add, under stirring conditions, a sufficient amount of alkaline earth metal ion in the form of a sufficient l the alkaline earth metal salt in sufficient quantity to add to the wet cake alkaline earth metal ions in an amount of 10 - 300 ppm, calculated on the dry, recoverable product in the slurry, stirs the resulting mixture to effect adhesion of the effective the degree of treatment with alkaline earth metal on the surface of the silica and finally dries and extracts the solid product. 10 15 20 25 7802901 -4 30! 10. A method according to claim 9, characterized in that the mineral acid consists of sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid or carbonic acid. 11. A method according to claims 9 and 10, characterized in that the alkaline earth metal ion consists of calcium, strontium or magnesium. 12. A method according to claims 9 and 10, characterized in that the alkaline earth metal ion is calcium and that it is added in the form of a salt, consisting of calcium hydroxide, calcium oxide, calcium nitrate or calcium fluoride. 13. A method according to claims 9 and 10, characterized in that the alkaline earth metal salt is reacted with the slurry of the wet cake at ambient temperature. 14. A method according to claim 13, characterized in that the silica treated with alkaline earth metal is dried by spray drying. 15. A method according to claims 9 and 10, characterized in that the alkali metal silicate is sodium silicate, the acidifying acid is sulfuric acid and that the alkaline earth metal ion is added in the form of calcium hydroxide to provide 10 - 100 ppm calcium ion, intimately connected with silicon oxide product.