AU680835B2 - Gel-type dentifrice - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 CO0M P LFTER AP R C~ T F T r~ A T T nW FOR A STANDARD PATENT S

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ORIGINAL

Name of Applicant: Adrs fo Sevie JOHNSON JOHNSON CONSUM~ER PRODUCTS, INC.

Akinori Takahashi and Hitoshi Watanabe SHELSTON WATERS Clarence Street SYDNEY NSW 2000 5* 5* Invention Title: "GEL-TYPE DENTIFRICE" The following statement is a full description of this invention, including the best method of performing it known to us:- Detailed Description of the Invention Field of the Invention The present invention relates to a gel-type dentifrice, and more specifically to a gel-type dentifrice having good fluidity due to a higher water content and having both excellent shape retention on a tooth brush and dispersibility in an oral cavity.

Prior Art Dentifrices are indispensable in order to maintain clean oral cavities to thereby prevent, for example, dental decay, periodontal diseases and foul breath. Dentifrices are generally inserted into an oral cavity by means of a toothbrush and the dentifrices are dispersed into the oral cavity by brushing. An appropriate amount of a dentifrice is drawn out of a container such as a tube, the amount applied onto the toothbrush S" measured by naked eye. Conventionally such tooth pastes characteristically have excellent shape retention.

In recent years, liquid- or gel-type (the term "gel-type" is generically used in the present specification) dentifrices with higher water content than the water content of conventional tooth pastes have become commercially available. These gel-type I dentifrices have a formulation such that they have considerably better dispersibility than conventional tooth pastes. The gel-type dentifrices are dispersible in any corner of the *oS.

oral cavity when dentifrices on a tooth brush are inserted into the oral cavity for dental brushing.

Problem that the Invention is to solve It has been suggested that gel-type dentifrices have a problem in relation to t'i shape retention. That is, a gel-type dentifrice cannot retain a constant shape once it is placed on a tooth brush, and the dentifrice penetrates into the brushes. Consequently, a user cannot measure by naked eye the amount of the dentifrice loaded on the tooth brush.

It is an object of the present invention to provide a dentifrice excellent in both shape retention on a tooth brush and dispersibility into an oral cavity.

Shape retention and dispersibility is related to the property herein called "thixotropy" (which property means that simple agitation or shaking causes the gel to form a fluid sol, the sol resuming the state of a gel if left to stand). In order to impart thixotropy to a substance it is generally known to employ thickening agents or binders in the dentifrice.

It has also conventionally been known to include sodium polyacrylate or a carboxyvinyl polymer in a dentifrice so as to enhance its shape retention.

Japanese Patent Publication No. Sho 61-5445 discloses a dentifrice containing 0.0005 to 0.5% by weight of a pulyacrylic acid having a molecular weight of 1,000,000 to 6,000,000 as a decay preventive agent. The polyacrylic acid is in a straight chain and is produced by polymerizing a monomer acrylic acid in an aqueous solution in the presence of persulfate salt.

e Japanese Patent Laid-open No. Sho 49-133535 discloses the use of a carboxyvinyl polymer. The reference discloses a tooth paste composition comprising calcium hydrogen phosphate.dihydrate as the main base, and carboxyvinyl polymer as a binder.

The Ca 2 solubilized from the calcium hydrogen phosphate dihydrate lowers the viscosity of the carboxyvinyl polymer and consequently a polyphosphate salt is included therein as a stabilizer. The viscosity of the carboxyvinyl polymer is lowered if it coexists with monovalent ions such as Na and K or divalent ions such as Ca 2 As has -4been described above, Ca 2 is contained in the dentifrice as calcium hydrogen phosphate.dihydrate is used as the base. Further Na is contained in other ingredients used (sodium lauryl sulfate as a foaming agent, sodium benzoate as an antiseptic, and the like). Such an environment is not suitable for carboxyvinyl polymers.

In order to prevent lowering of the viscosity of carboxyvinyl polymers due to these ions, Japanese Patent Laid-open Nos. Sho 61-15826, 61-15825 and 61-126012 propose compounding xanthum gum, sodium carboxymethyl cellulose (CMC) and i-type carrageenan, respectively in the dentifrice.

In formulating gel-type dentifrices with higher water contents, the single use of a carboxyvinyl polymer as a binder cannot bring about satisfactory shape retention due to the decrease in the viscosity of the carboxyvinyl polymer, due to the presence of ions such as Na Ca 2 and the like. The combined use of a carboxyvinyl polymer with other binders to maintain shape retention, for example, by mixing with binders such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carrageenan, xanthum gum, and sodium alginate, does not produce the preferred dispersibility. In other words, conventional dentifrices cannot satisfy both shape retention and dispersibility. It would be desirable to produce a gel-type dentifrice resistant to ions such as Na+, K and Ca

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Means for Solving the Problems To overcome the problems described above, the present invention provides a geltype dentifrice comprising a cross-linked type salt resistant carboxyvinyl polymer being a copolymer of polyacrylic acid and polyallyl sucrose and selected on the basis that the viscosity of the carboxyvinyl polymer in an aqueous solution containing 1% by weight of the polymer and 0.3% by weight of sodium ions is decreased by 20% or less than the viscosity of the same solution in the absence of sodium ions; a sodium ion releasing substance; and water.

The present inventors have made investigations into the problems described above, and have found that the shape retention can be remarkably improved by employing a salt resistant carboxyvinyl polymer (one having a property such that its viscosity is not decreased even in the presence of a salt, i.e. the solubilized ions thereof) characterized in that the viscosity of an aqueous solution containing 1% of the carboxyvinyl polymer and 0.3% (in the present Specification, by weight" is meant unless otherwise stated) of Na+ is decreased by 20% or less than the viscosity of such a solution without Na contained therein. The inventors have thereby achieved a gel-type dentifrice capable of exhibiting shape retention similar to those of conventional tooth pastes, and enhanced dispersibility in the oral cavity.

The carboxyvinyl polymer used in the present invention is defined in the Japanese Cosmetics Raw Material Standard (Japanese Official Standard Act Association, eds.), and is different from sodium polyacrylate which is also disclosed therein. In this regard, when the polyacrylic acid salt is prepared in the form of an aqueous sodium polyacrylate solution as described above, the salt is in linear state without branched chains or crosslinking as shown in Chemical formula 1, whereas the carboxyvinyl polymer used in the present invention is a copolymer of acrylic acid and allyl sucrose (as the hydrophilic -6group). When dissolved in water for neutralization and swelling, the carboxyvinyl polymer is cross-linked similarly to that sh~wn in Chemical formula 2; Chemical formula 1 COO N ai N&O0C (Solid line represents polyacrylic chain) COO ~Na+ Sodium polyacrylate Chemical formula 2 0 0 0* 0a 000000 0

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0 0 U'slid line represents carboxyvinyl chain) Cross linked type carboxyvinyl polymer Therefore, the carboxyvinyl polymer is of a totally different structure from that of linear polyacrylic acid 172.15.00 DodAWLS -7and thus exhibits different properties from those of such polyacrylic acid.

The cross-linked type salt resistant carboxyvinyl polymer is illustrated, for example, by HIVISWAKO 103, 104 and 106, manufactured by WAKO Chemical Co., Ltd. Among them, HIVISWAKO 105 is preferred due to its higher salt resistance.

The carboxyvinyl polymer used in the invention shows completely different properties to electrolytic salts from the carboxyvinyl polymers (not salt-resistant) disclosed in prior Japanese Patent Laid-open No. Sho 49-133535 (for example, Carbopol 934, 940 and 941 manufactured by B.F. Goodrich Co., Ltd). That is, non salt-resistant carboxyvinyl polymers are generally under the influetice of the effect of an electric shield due to the presence of other electrolytes, as in the case of linear sodium polyacrylate, such that the electrostatic power among the fixed ions (Na) attached to the polymer is decreased, with the result that widely elongated multi-branched chains shrink in the form of a yarn ball. Thus, the apparent viscosity distinctively decreases.

In terms of the decrease in apparent viscosity, a comparison was made between HIVISWAKO 105 and Carbopol 941. Powdery HIVISWAKO 105 and Carbopol 941 were each prepared into a 1% dispersion in various aqueous NaCI and CaC12 solutions.

The dispersions were then neutralized with 10% NaOH in order to measure the viscosity.

The viscosity was measured with a rotational viscometer of Type B8H (at 20 rpm and 0 The results are shown in Tables 1 and 2.

[Table 1] Na Effect Na+ Concentration 0% 0.02% 0.04% 0.12% 0.20% 0.30% Samples HIVISWAKO 105 8,200 9,520 9,780 7,580 7,420 6,900 Carbopol 941 8,000 9,200 8,380 6,740 5,240 2,620 SRy (Unit: cP) ^X 0 3r -8- [Table 2] Na2+ Effect Na+ Concentration 0% 0.014% 0.027% 0.082% Samples HIVISWAKO 105 8,200 10,500 9,800 8,460 Carbopol 941 8,000 9,580 9,440 6,860 (Unit: cP) Figs. 1 and 2 respectively illustrate the results of Tables 1 and 2, in graphs for ready understanding.

As shown in the Tables ,aid the Figures, the decrease in the viscosity of HIVISWAKO 105 when Na was contained in a concentration of 0.3% in the dispersion was 16%, whereas a decrease of 67% was observed in the case of Carbopol 941.

In the case of Ca 2 addition, HIVISWAKO 105 showed an increase in its viscosity ;;with the addition of Ca 2 compared with its viscosity without Ca 2 addition. At a Ca 2 concentration of 0.082 Carbopol 941 had a viscosity lower than its viscosity without Ca 2 addition.

Because Na releasing substances such as sodium fluoride, sodium lauryl sulfate, saccharin sodium should be compounded with a dentifrice, it is preferred, in terms of the formulation of the dentifrice, that HIVISWAKO 105 is used in the present invention as it does not result in a decrease in the viscosity of the formulation, even in the presence of ions such as Na and Ca 2 Preferably, the carboxyvinyl polymer used in the present invention has a molecular weight of from 1,000,000 to 2,000,000. If the molecular weight is less than 1,000,000, shape retention is deteriorated; on the contrary if the molecular weight is above 2,000,000, poorer dispersibility results.

IT O In terms of shape retention, the carboxyvinyl polymer in the gel-type dentifrice of the present invention preferably has a viscosity of 1,500 to 40,000 cP when neutralized in an aqueous 0.2% solution thereof, more preferably the viscosity is 2,000 to 30,000 cP.

The amount of the carboxyvinyl polymer used in the dentifrice is preferably 0.01 to 5% by weight. Satisfactory thixotropy is not exhibited if less than 0.01% by weight is used and the viscosity is too high if greater than 6% by weight is used. More preferably, the amount used is 0.1 to 2% by weight.

The dentifrice of the present invention may be mixed with effective amounts of fluorides as effective ingredients such as sodium fluoride and sodium monofluorophosphate; disinfectants such as chlorhexidine, cetylpyridinium chloride, trichlorsan and the like; lysozyme chloride, dextranase, lysate enzymes, mutanase, arexidine sorbate, hinokitiol, alkylglycine, alkyldiaminoethyl glycir.e salt, allantoin, saminocaproic acid, tranexamic acid, azulene, vitamin E, polyphosphoric acid, sodium yrophosphate, water-soluble dihydrogen phosphate or hydrogen phosphate, quarternary ammonium compounds, sodium chloride and the like. The dentifrice may also contain emollients such as glycerol, sorbitol, propylene glycol, polyethylene glycol and the like; binders such as sodium carboxymethyl cellulose, hydroxypropyl cellulose, sodium alginate and the like. Furthermore, the dentifrice of the present invention may contain polishing agents such as colloid-type silica, precipitating silica, sodium aluminosilicate, insoluble sodium metaphosphate, hydrate alumina, baked alumina, calcium pyrophosphate, calcium hydrogen phosphate.dihydrate, calcium carbonate and the like; foaming agents such as sodium alkylsulfate, olefin sulfonate, sodium laurylsarcosinate, sugar ester and the like; essential oils such as peppermint, anetol and the like; perfume fi fi fit. fi fi f f -idmaterials such as 1-menthol, carvone, eugenol, anethole and the like; sweeteners such as saccharin sodium, stevioside, neohesperidin dihydrochalcone, glycyrrhetin, perillartine, thaumatin, and the like; and antiseptics such as methyl-, ethyl-, propyl-, pentyl esters of p-hydroxybenzoid acid.

Examples Examples of the present invention will now be explained in detail.

Examples 1-4 Dentifrices according to the present invention having compositions shown in the following Table 3 were prepared.

[Table 3] Composition of Samples Sample No. Examples Comparative Ingredients 1 2 3 4 Examples Silica 10.0 5.0 3.0 5.0 Viscous silica 2.0 HIVISWAKO 105 1.0 0.75 0.5 0.8 Carbopol 941 0.75 Xanthum gum 0.2 0.2 0.5 0.2 0.2 CMC-Na 0.1 0.2 0.2 0.1 sorbit 35.0 35.0 30.0 60.0 35.0 Glycerin 5 0 5.0 2.0 Sodium lauryl 1.5 1.5 1.5 1.5 sulfate sodium fluoride 0.2 0.2 0.2 0.2 0.2 Sodium benzoate 0.1 0.1 0 0. 0.1 0.1 Perfume 1.0 1.0 1.0 1.0 Distilled water remainin remainin remaining remaining remaining part g part g part part part (Unit: -11 Comparative Examples For comparison with the above Examples, Comparative Examples of the compositions shown in the above Table 3 were prepared. The carboxyvinyl polymer used was of a multi-branched chain type, namely Carbopol 934 (having a molecular weight of from 1,000,000 to 1,500,000) manufactured by B.F. Goodrich Co., Ltd.

According to a four-score method, thirty panelists then functionally assessed the shape retention (which should be of a column-type shape) of the dentifrices of the Examples 1 to 4 and the Comparative Examples, when placed on tooth brushes. The standard for assessment for determining each individual score was as follows: !0 Score 4: extremely good (nearly column-type) Score 3: good (more or less column-type) Score 2: bad (slightly loose) Score 1: very bad (dentifrice penetrates into the tooth brush where brushes are planted).

The dentifrices placed on tooth brushes ,vere then placed into each individual's 0 mouth and subjected to dental brushing for two minutes. No water was applied to the brushes at this time, and the dentifrices were placed fully on the brush. The same amount of dentifrices was used per person. Two minutes later, the dispersibility of the dentifrice was subjected to a functional assessment according to a five-score method.

The standard of assessment for determining each individual score was as follows: Score 5: extremely good Score 4: good Score 3: normal -12- Score 2: bad Score 1: very bad.

The results of the functional assessments concerning shape retention and dispersibility (collectively called "preferable property") are shown in Table 4.

[Table 4] Results of Assessment of Preferable Property Sample No. Examples Comparative Preferable 1 2 3 4 Examples Property Shape 4 points 1 0 0 0 retention 3 points 25 23 21 26 0 2 points 4 7 9 4 1 point 0 0 0 0 Dispersib- 5 points 10 16 15 20 1 ility 4 points 15 13 14 5 4 3 points 5 1 1 5 2 points 0 0 0 0 14 1 point 0 0 0 0 0 (Unit: man) Tables 3 and 4 show that all of the dentifrices of Examples 1 to 4 show good values with respect to shape retention (such as a score of almost 4) and scores of 4 to with respect to dispersibility. The Comparative Examples were poor with respect to both shape retention and dispersibility. The reason for the good shape retention of the Examples is that the carboxyvinyl polymer used does not result in a drastic decrease in viscosity even with the coexistence of a salt such as sodium fluoride, sodium benzoate and sodium lauryl sulfate, which release cations when dissolved in water (distilled water in the dentifrices).

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440 *4*4 -13- The present inventors herein disc"'se a dentifrice comprising the following ingredients as the most preferred embodiment of the gel-type dentifrice of the present invention:a gel-type dentifrice containing 5.00% of anhydrous silicate (product name: Sylosphere) as a polishing agent; 0.50% of xanthum gum and 0.75% of carboxyvinyl polymer (product name: HIVISWAKO 105) as binders; 17.50% of finely ground sorbit and 4.00% of 95% glycerin as emollients; 1.00% of sodium lauryl sulfate as a foaming agent; 0.20% of sodium fluoride and 0.02% of 2,4,4' -trichloro-2-hydroxydiphenyl ether (trichlorsan) as pharmaceutically active agents; 0.15% of methyl-p-hydroxy benzoate, 0.10% of propyl-p-hydroxy benzoate and 0.05% of butyl-p-hydroxy benzoate as antiseptics; 0.02% of saccharin sodium as a sweetener; 0.08% of a perfume; a slight amount of Food Green #3 as a coloring agent; a slight amount of sodium hydroxide and 0.03% of hydrochloric acid as pH adjusters; and distilled water as the remainder.

It was confirmed that the shape retention and dispersibility of the dentifrice was 15 good.

Advantages of the Invention As has been described above, the liquid- or gel-type dentifrice of the present invention have good properties such that good dispersibility is exhibited once dental brushing is initiated and the dentifrice can maintain a constant shape as in the case of 20 general tooth pastes when placed on a tooth brush.

-14- Brief Description of the Drawings Fig. 1 is a graph depicting the relation between the viscosity change of a salt resistant carboxyvinyl polymer and a non-salt resistant carboxyvinyl polymer, in the presence ofNa.

Fig. 2 is a graph depicting the relation between the viscosit, hange of a salt resistant carboxyvinyl polymer and a non-salt resistant carboxyvinyl polymer, in the presence of Ca a e o

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Claims (18)

1. A gel-type dentifrice comprising: a cross-linked type salt resistant carboxyvinyl polymer being a copolymer of polyacrylic acid and polyallyl sucrose and selected on the basis that the viscosity of the carboxyvinyl polymer in an aqueous solution containing 1% by weight of the polymer and 0.3% by weight of sodium ions is decreased by 20% or less in comparison with the viscosity of the same solution in the absen, e of sodium ions; a sodium ion releasing dentifrice substance; and water.

2. The dentifrice according to claim 1 wherein the carboxyvinyl polymer has a molecular weight of from 1,000,000 to 2,000,000.

3. The dentifrice according to claim 1 or 2 wherein the carboxyvinyl polymer is selected on the basis that the viscosity of a neutral solution containing 0.2% by weight of the polymer is from 1,500 to 40,000 cP. S* 15

4. The dentifrice according to any one of the preceding claims wherein the carboxyvinyl polymer is present in an amount of 0.01 to 5% by weight of the dentifrice.

5. The dentifrice according to claim 4 wherein the carboxyvinyl polymer is present in an amount of 0.1 to 2% by weight of the dentifrice.

6. The dentifrice according to any one of the preceding claims wherein the sodium 20 ion releasing substance is sodium fluoride, sodium lauryl sulfate and/or saccharin sodium. I~ -16-

7. The dentifrice according to any one of the preceding claims further comprising one or more of a pharmaceutical effective ingredient, a disinfectant, an emollient, a binder, a polishing agent, a foaming agent, an essential oil, a perfume, a sweetener, an antiseptic, lysozyme chloride, dextranase, lysate enzymes, mutanase, arexidine sorbate, hinokitiol, alkylglycine, alkyldiaminoethyl glycine salt, allantoin, s-aminocaproic acid, tranexamic acid, azulene, vitamin E, polyphosphoric acid, sodium pyrophosphate, water-soluble dihydrogen phosphate or hydrogen phosphate, quarternary ammonium compounds or sodium chloride.

8. The dentifrice according to claim 7 wherein the pharmaceutically effective ingredient is sodium fluoride and/or sodium monofluorophosphate.

9. The dentifrice according to claim 7 or 8 wherein the disinfectant is chlorhexidine, cetylpyridinium chloride and/or trichlorsan. S*

10. The dentifrice according to any one of the claims 7 to 9 wherein the emollient is glycerol, sorbitol, propylene glycol and/or polyethylene glycol. S 15

11. The dentifrice according to any one of claims 7 to 10 wherein the binder is sodium carboxymethyl cellulose, hydroxypropyl cellulose and/or sodium alginate.

12. The dentifrice according to any one of claims 7 to 1 wherein the polishing agent is colloid-type silica, precipitating silica, sodium aluminosilicate, insoluble sodium S metaphosphate, hydrate alumina, baked alumina, calcium pyrophosphate, calcium 20 hydrogen phosphate.dihydrate and/or calcium carbonate.

13. The dentifrice according to any one of claims 7 to 12 wherein the foaming agent is sodium alkylsulfate, olefin sulfonate, sodium laurylsarcosinate and/or sugar ester. g c I -17-

14. The dentifrice according to any one of claims 7 to 13 wherein the essential oil is peppermint and/or anetol.

The dentifrice according to any one of claims 7 to 14 wherein the perfume is 1- menthol, carvone, eugenol and/or anethole.

16. The dentifrice according to any one of claims 7 to 15 wherein the sweetener is saccharin sodium, stevioside, neohesperidin dihydrochalcone, glycyrrhetin, perillartine and/or thaumatin.

17. The dentifrice according to any one of claims 7 to 16 wherein the antiseptic is methyl-, ethyl-, propyl- or pentyl ester(s) of m- or p-hydroxybenzoic acid.

18. A gel-type dentifrice substantially as herein described with reference to any one of the Examples but excluding any comparative examples. DATED this 29th Day of May, 1997 "JOHNSON AND JOHNSON CONSUMER PRODUCTS, INC. Attorney: RUTH M. CLARKSON Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS *o• *oo *oo *e~ I r 9 111 PPPB~I~sC~C~ Abstract The present invention intends to provide a gel-type dentifrice having both of good shape retention on tooth brushes and dispersibility in oral cavity. Constitution 0 0 foe 0 a *as 0 0 oa..o. aa S 0 a a a a a 00 The gel-type dentifrice of the present invention contains a salt resistant carboxyvinyl polymer of cross linked type, characterized in that the viscosity of an aqueous 1 carboxyvinyl polymer solution containing 0,3 of Na is decreased only by or less than the viscosity of such solution without Na+ contained therein. I~ q ~I I- ~pll ll/s