Background Art In general, teeth cavities are known to be caused by foods with high sugar content and oral bacteria on the teeth having weak resistance. To protect against teeth cavities, the above causes should be addressed. Further, the plaque is a membrane produced on the teeth by the oral bacteria, and changed to tartar due to the deposition of multivalent ions contained in the foods over time. Since such tartar is colored by color deposition and becomes brown, it makes an unfavorable impression and also causes periodontal diseases. Thus, the tartar should be preferably removed from the teeth.

Preparation methods of the toothpaste for use in the protection against teeth cavities and removal of the plaque and tartar from the teeth are exemplified as follows.

Korean Patent No. 012156 discloses a method of removing multivalent ions, such as calcium or magnesium, in the saliva, by using powders or granules of neutral zeolite (4A) resulting from neutralization of zeolite. However, the use of the neutralized zeolite leads to a decreased removal function of calcium or

magnesium. Further, if the zeolite is used in larger amounts to solve the above problem, the prepared toothpaste has a bitter taste due to the excessive addition of the zeolite.

In EP 0473171 and U. S. Patent No. 5,206, 010, there is disclosed a toothpaste composition comprising a water-insoluble inorganic material (zeolite, synthetic alumino silicate, calcium diphosphate, etc. ) mixed and then granulated with 5-10 wt% of an organic binder (polystyrene latex, polyacrylic stearate, wax, etc. ) insoluble to water. However, the above patent is disadvantageous in terms of the use of 5-10 wt% of the organic binder having no connection with the effects of the toothpaste, to granulate the water-insoluble inorganic material.

Further, WO 02/45677 discloses that zeolite granules are used to remove the tartar and plaque from the teeth, however the zeolite granules alone exhibit poor abrading function and thus, an abrasive should be additionally used.

Disclosure of the Invention Therefore, it is an object of the present invention to provide zeolite granules for use in toothpaste, having superior abrading function by high strength.

Another object of the present invention is to provide a toothpaste composition having an excellent removal function of tartar from the teeth, obtained by a simplified preparation process while omitting a separate adding process of fluorine.

Best Mode for Carrying Out the Invention Based on the present invention, zeolite granules for use in toothpaste include 10 to 50 wt% of silica as an abrasive, and 0.5 to 3 wt% of a fluorine compound as a strength enhancer, added to zeolite. A toothpaste composition of the present invention includes 0.5 to 40 wt% of the zeolite granules.

Zeolite has a cation exchange capacity, thus acting to effectively remove

plaque and tartar from the teeth. In the present invention, with the intention of solving the problems in the related arts, silica having an abrading function is used instead of an organic binder to prepare zeolite. Thus, there is not required a separate mixing process of the zeolite granules and the abrasive.

However, silica has higher expansion efficiency than that of zeolite, upon dryness and wetness. In cases where silica is used as a binder of the zeolite granules, the resulting granules are physically weak and thus fractured upon a stirring process to produce the toothpaste. Hence, such granules cannot be applied for the toothpaste.

Therefore, in the present invention, silica is suspended to water to prepare slurry, which is then added with fluoride (selected from the group consisting of hydrofluorosilic acid, sodium fluorosilicate, potassium fluorosilicate, hydrofluoric acid, sodium fluoride, potassium fluoride, monofluorophosphoric acid, sodium monofluorophosphate, potassium monofluorophosphate, magnesium fluorosilicate, and mixtures thereof). Thereby, a part of silica is converted to fluorosilicate, which is then used as the binder of the zeolite granules, thus preparing the zeolite granules having desired strength.

By using the fluoride, sodium contained in the zeolite reacts with fluorosilicate in silica to produce NaF. Thereby, the strength increases, and, as well, stability problems of the toothpaste due to high pH upon the use of the zeolite granules can be overcome. Also, a separate adding process of fluorine for use in protection against teeth cavities may be omitted.

The fluoride is suitably added in the amount of 0.5-3. 0 wt%. If the amount is less than the above lower limit, the resulting granules are very weak in strength, thus exhibiting no abrading function. Meanwhile, if the amount exceeds the above upper limit, the obtained granules are very strong and thus may damage the surface of the teeth. The strength required for the granules corresponds to the extent of the granule particles being broken when applied with 5-20 g of loads.

The zeolite has excellent cation exchange capacity, and thus the amount

of zeolite in the granules should be at least 47 wt%. The zeolite alone has high calcium ion-sequestering capacity of about 300 mg/g but is poor in strength, and hence cannot be used for toothpaste as it is. Even though the fluoride and silica are mixed together to enhance the strength of the granules, the calcium ion- sequestering capacity should be maintained at the level not less than 150 mg/g.

For this, the zeolite in the granules should be used in the amount not less than 47 wt%. When the granules are added in typical amounts to the toothpaste, the calcium ion-sequestering capacity of the toothpaste is maintained at the level not less than 25 mg/g.

As for a preparation method of the zeolite granules, the zeolite may be added with silica and fluorine components and thus directly granulated. Thusly obtained first granules may be additionally coated with a suspension having relatively high silica amount. When the first granules are coated, the silica component is present in larger amounts on the granules, thus further increasing fracture strength.

As for the first granules, it is preferable that 5 to 15 wt% of silica is added to the zeolite. As for the suspension for surface coating, it is preferable that 40 to 50 wt% of silica is added to the zeolite. Since the amount of silica is high on the surface of the granules, the coated layer becomes transparent while absorbing water.

The prepared zeolite granules are dried at 100-120°C to have water content of 15 wt% or less, sintered in a rotary kiln at 250-350°C, and then sieved through a standard mesh of 0.1-1. 0 mm, and preferably, 0.2-0. 6 mm.

A better understanding of the present invention may be obtained through the following examples and comparative examples which are set forth to illustrate, but is not to be construed as the limit of the present invention.

Preparative Example 1 Into a granulating machine having 7.2 kg of zeolite (solid content 80 wt%), 4 kg of precipitated silica was introduced and mixed for 5 min, to obtain a mixture

of zeolite and silica. The mixture was slowly added with 7.15 kg of water in which 250 g of monofluorophosphoric acid was dissolved, to form granules. The granules were dried at 105°C for 11 hours to have a water content of 12.5 wt%, and then passed through a rotary kiln having a length of 3.5 m and an inner diameter of 200 mm at 300°C, to prepare granules having a water content of 5.8 wt%. Such granules were sieved through a 40-70 mesh, thereby obtaining desired granules for use in a toothpaste.

The granules have a fracture strength of 7-16 g/number, with the variation of the strength, and a calcium ion-sequestering capacity of 175 mg/g.

Preparative Example 2 4 kg of water was added with 1 kg of precipitated silica to make slurry, which was further added with 400 g of 50% aqueous solution of monofluorophosphoric acid, to obtain'slurry A'. Separately, 3 kg of precipitated silica was added to 3 kg of water to obtain slurry having 50 wt% of silica, which was then mixed with 100g of 50% monofluorophosphoric acid, to prepare'slurry B'for use in coating.

Into a granulating machine having 7.2 kg of zeolite (solid content 80 wt%), the slurry A was slowly introduced to form granules. After 20 min. , the slurry B for coating was added to the granules and then the granulation was further performed for 20 min. , thus obtaining coated granules. Such granules were dried at 105°C for 11 hours to have a water content of 13 wt%, and then passed through a rotary kiln having a length of 3.5 m and an inner diameter of 200 mm at 300°C, to prepare granules having a water content of 6 wt%, which were thereafter sieved through a 40-70 mesh, thereby obtaining desired granules for use in a toothpaste.

The granules have a fracture strength of 14-20 g/number, with decreasing the variation of the strength. From this, it can be found that the strength of the granules resulting from the present example is further increased to the extent of 20-

30%, compared to that of the granules obtained in Preparative Example 1. In addition, a calcium ion-sequestering capacity is 158 mg/g.

Comparative Preparative Example 1 Granules for use in a toothpaste were prepared in the same manner as in Example 2, with the exception that 350g (50% solution 700g) of monofluorophosphoric acid as a fluorine compound was used. The obtained granules have a fracture strength of 25-30 g/number, which is too strong to use as toothpaste and tastes bitter.

Preparative Examples 3 to 5 and Comparative Preparative Example 2 and 3 Each toothpaste composition was prepared according to known methods using components shown in Table 1, below. As such, the zeolite granules obtained in Preparative Example 2 were used.

TABLE 1 Use Component P. Ex. 3 P. Ex. 4 P. Ex. 5 C. P. Ex. 2 C. P. Ex. 3 Abrasive. Precipitated Silica-5-20 20 Moisturizing Agent 70% Sorbitol 50 50 50 50 50 Surfactant Sodium Lauryl Sulfate 2 2 2 2 2 Binder Xanthan Gum 0.8 0.8 0.8 0.8 0.8 Anti-plaque and Anti-tartar Potassium 2. 3 4.5 Agent Pyrophosphate Zeolite Granules 30 15 35 Fluorine NaF---0. 22 0.22 Additive Flavor, Sweetener 1. 1 1. 1 1. 1 1.1 1.1 Pure Water H20 16. 1 26.1 11.1 23.58 21.38 Total 100 100 100 100 100 Example 1 Anti-tartar Effect The sequestering capacity with respect to calcium ions mainly causing the tartar on the teeth was determined by measuring the ion binding capacity, and thus the anti-tartar efficacies of the toothpaste compositions of the present

invention were compared. For this, 1 g of respective compositions obtained in preparative examples and comparative preparative examples were dispersed in 50 g of water, added with 50 mL of 0.05 M EDTA solution, and then titrated with 0. 05N calcium chloride solution. The results are shown in Table 2, below.

TABLE 2 P. Ex. 3 P. Ex. 4 P. Ex. 5 C. P. Ex. 2 C. P. Ex. 3 Sequestering Capacity 59.3 30.2 72.3 21.4 51.2 (mgCaC03/g) From the above Table 2, it can be seen that the toothpaste compositions obtained in preparative examples have a higher calcium ion-sequestering capacity than that of the compositions of comparative preparative examples.

Example 2 Protection Effect against Teeth Cavities Apatite (Ca3 (P04) 2) as a main component of the teeth was pulverized to the size of 2-3 mm and the surface thereof was abraded using a sand mill, to prepare an apatite ball. 10 g of the apatite ball was mixed with respective compositions obtained in preparative examples and comparative preparative examples to have 0.04% of fluorine, and allowed to stand at room temperature for 24 hours, washed with water, and then incorporated into 10 mL of an acetate buffer solution, pH 5.0, for 20 min. The Ca ion present in the solution was measured by use of an ICP, to compare the protection effects of fluorine against teeth cavities. The results are given in the following Table 3.

TABLE 3 P. Ex. 3 P. Ex. 4 P. Ex. 5 C. P. Ex. 2 C. P. Ex. 3 Ca ion in Solution 11.3 11.9 11.5 11.4 11.7 (pom)

From the results of Table 3, it can be seen that the protection effects of fluorine are similar even though fluorine is added upon preparation of the zeolite granules as in preparative examples or separately added as in comparative preparative examples.

Example 3 Comparison of Remaining Effective Content of Fluorine over Time Respective toothpaste compositions obtained in preparative examples and comparative preparative examples were stored in a thermohydrostat at room temperature and 50°C. The remaining effective content of fluorine over time was determined by measuring potential difference with the help of an ion meter (model Orion 710A). The results are given in Table 4, below.

TABLE 4 Storing at 50°C (days) 30 60 90 P. Ex. 3 85 83 68 P. Ex. 4 84 83 69 P. Ex. 5 86 83 68 C. P. Ex. 2 58 53 48 C. P. Ex. 3 58 53 48 Storing at Room Temp. (days) 30 60 90 120 180 240 360 P. Ex. 3 99 98 97 95 95 86 84 P. Ex. 4 99 98 97 94 94 87 82 P. Ex. 5 99 99 98 95 95 87 83 C. P. Ex. 2 98 97 96 92 92 75 65 C. P. Ex. 3 98 98 96 93 93 76 68 From the above Table 4, it can be shown that the toothpaste compositions obtained in preparative examples are superior in storability depending on the effective content of fluorine over time.

Industrial Applicability

As mentioned above, the present invention provides fluorine-containing zeolite granules for use in toothpaste, and a toothpaste composition comprising the same. Upon application of the zeolite granules to the toothpaste, the prepared toothpaste is advantageous in terms of superior protection efficacies against teeth cavities and high anti-plaque and anti-tartar effects, and drastically increased storability.

Moreover, in the present invention, there is not required a separate adding process of fluorine to provide resistance to tooth decay upon preparation of the toothpaste composition.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.