GB2187095A - Dental cream package - Google Patents

Abstract

Dental cream in contact with a polyolefin resin surface of a package such as a laminate tube, a mechanical dispenser or flexible sachet comprises at least 20% by weight of a liquid vehicle comprising water, glycerine and sorbitol, the weight ratio of glycerine to sorbitol being 0.25:1 to 3:1, a solid vehicle comprising 0.05-10% by weight of gelling agent and 20-75% by weight of dentally acceptable water-insoluble polishing material, at least a major portion of which is alpha-alumina trihydrate and benzoic acid to reduce pH to 6-8.5 and prevent syneresis due to contact between the dental cream and the polyolefin resin.

Description

SPECIFICATION Dental Cream Package This invention relates to a dental cream packaged in a plastic laminate tube, mechanical dispenser, flexible sachet or the like. In particular it relates to a dental cream in compatible contact with a polyolefin surface of a package such as a plastic laminate dental cream tube, mechanical dispenser or flexible sachet.

Dental creams have been packaged for many years in flexible metal tubes such as a wax lined lead tubes, unlined aluminium tubes or aluminium tubes having an epoxy resin lacquer coating thereon. In recent years flexible form-retaining laminated plastic tubes have been increasingly used.

Plastic laminated dental cream tubes typically comprise an inner polyolefin resin layer which is in direct contact with the dental cream and at least one intermediate layer, including an aluminium foil layer which inhibits loss of flavour from the dental cream. Desirably, an intermediate paper layer which provides stiffness to the tube is also present. The outer layers are typically of polyolefin resins, one of which may be coloured white and bears printed indicia with a clear polyolefin laminate overlay to protect the indicia.

Additional intermediate laminate layers of flexible plastic may also be present.

Mechanical dental cream dispensers may also have a polyolefin surface in contact with dental cream contained therein. In fact, the polyolefin itself may be the housing of the dispenser. Flexible sachet packets may also have a polyolefin surface in contact with dental areas.

Dental creams typically contain a liquid vehicle of water and humectant, a gelling agent solid vehicle and a water-soluble dental polishing agent. Dental creams composed of such materials wherein the humectant comprises glycerine and sorbitol and the polishing material is at least in major part an alpha alumina trihydrate have been successfully packaged in flexible metal toothpaste containers including aluminium tubes having an internal coating of an epoxy resin lacquer layer.However, it has been observed that, when such dental creams are packaged in containers having an interior polyolefin surface such as plastic laminated dental cream tubes, mechanically operated dental cream dispensers orflexible sachets, syneresis occurs and liquids separate from solids, rendering the dental cream undesirable, when the pH of the dental cream is reduced with a water-soluble material which provides phosphate ion. In commonly assigned U.S. Patent Application for "Packaged Dental Cream" filed November 27, 1985 of Sandra Lee Schelm, syneresis of such a dental cream in contact with polyolefin surface is overcome by including polyethylene glycol of average molecular weight of about 200--1000 in the dental cream.

It is an advantage of this invention that phase separation of a dental cream packaged in contact with polyolefin material is substantially prevented with an acidifying agent.

In accordance with certain of its aspects, this invention relates to a dental cream package wherein the said dental cream is in direct contact with a polyolefin resin surface, the said dental cream comprising at least about 20% by weight of a liquid vehicle comprising water, glycerine and sorbitol, the weight ratio of glycerine to sorbitol being from 0.25:1 to about 3:1, a solid vehicle comprising about 0.05%-i 0% by weight of gelling agent, about 2075% by weight of a dentally acceptable water-soluble polishing material, at least a major portion of which is alpha-alumina trihydrate and benzoic acid to reduce the pH of the dental cream to about S8.5.

In dental cream formulations, the liquids and solids are necessarily proportioned to form a creamy mass of desired consistency which is extrudible from its package. The liquids in the present dental cream comprise chiefly water, glycerine and sorbitol. The total liquid vehicle comprises at least about 20% by weight of the formulation. It is preferred to use also a gelling agent in dental creams such as the natural and synthetic gums and gumiike materials, e.g. carrageenans such as Irish moss, gum tragacanth, sodium carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium alginate, guar gum, starch, xanthan and the like, including mixtures thereof. Irish Moss, sodium carboxymethyl cellulose and hydroxyethyl cellulose including mixtures thereof are compatible particularly and are preferred gelling agents.The gum content is usually in an amount of about 0.0510% and preferably about 0.55% by weight of the formulation.

Water is generally incorporated into the dental cream in an amount of about 1050% by weight, preferably about 1535%. Glycerine and sorbitol together generally comprise about 1550% by weight, preferably 2035% of the dental cream, with the weight ratio of glycerine to sorbitol being from about 0.25:1 to 3:1, typically from about 0.25:1 to about 0.8:1 and preferably from 0.6:1 to about 0.8:1. Amounts of sorbitol as used herein are of sorbitol syrup, as commercially available, that is 70% by weight sorbitol in 30% by weight of water.

Dentally acceptable water-insoluble polishing agent is present in the dental cream in an amount of about 2075% by weight, preferably 3560%. At least the major portion, that is, about 50100% of the polishing material is alpha-alumina trihydrate. The minor portion of the polishing material, if present, typically comprises about 520% by weight of the polishing material. Dicalcium, phosphate dihydrate, anhydrous dicalcium phosphate, calcium carbonate, tricalcium phosphate, calcium pyrophosphate, dimagnesium phosphate trihydrate, magnesium carbonate, calcined alumina, zirconium silicate and insoluble sodium metaphosphate are typical.

Dentally acceptable water-insoluble alpha-alumina toothpaste is typically employed in small particle size, e.g. wherein at least about 85% of the particles are smaller than 20 microns and is preferably hydrated, such as that classified as gibbsite (alpha alumina trihydrate) and normally represented chemically as Al2033H2O or Al(OH)3. The average particle size of gibbsite is generally about 6 to 9 microns. However, larger particle size alpha-alumina trihydrate, e.g. wherein 2070% of the particles exceed 20 microns in size, may also be used.A particularly desirable grade of alpha-alumina trihydrate, available from Alcoa as C-333 is a fine grade of gibbsite having the following size distribution: Microns Percent less than 30 94-99 less than 20 85--93 less than 10 5667 less than 5 2840 Other desirable grades of alpha-alumina trihydrate include BACO AF-230 and BACO AF-260, available from British Alcoa Aluminium, SH100 from Rhone Poulenc, and OS4608 and ON4608 grades from Martinswerk.

Unless the pH of the dental cream is adjusted, dental cream containing a substantial amount of alpha-alumina trihydrate is generally highly alkaline, e.g. about pH 9-10.5. Accordingly acidic materials are often added to such dental creams in order to reduce the pH, typically to about 6 to 8.5. As set forth above, when water-soluble phosphate materials are employed to produce such reduction in alkalinity, syneresis occurs unless a further additive, polyethylene glycol of average molecular weight of about 200-1000, is present. In the present specification reference to the pH is as measured in a 20% aqueous slurry.

In the present invention it has been found that when the pH is adjusted to about 6-8.5 with benzoic acid syneresis in the presence of a polyolefin package surface is prevented. Typically about 0.150.5% by weight of benzoic acid is effective to produce a pH of about 6-8.5 with various grades of alpha-alumina trihydrate in dental cream. It is preferred that the pH of the dental cream be about 7.58.5. Reference to pH herein is to a 20% by weight aqueous slurry of dental cream.

Organic surface-active agents may be used in the dental cream of the present invention to achieve increased prophylactive action, assist in achieving thorough and complete dispersion of the compositions of the present invention throughout the oral cavity, and render the dental creams more cosmetically acceptable. The organic surface-active material may be anionic, nonionic, ampholytic or cationic in nature, but it is preferred to employ as the surface-active agent a detersive material which imparts to the composition detersive and foaming properties.Suitable types of such detergents are water-soluble salts of higher fatty acid monoglyceride monosulphates, such as the sodium salt of the monosulphated monoglyceride of hydrogenated coconut oil fatty acids, higher alkyl sulphates, such as sodium lauryl sulphate, alkylaryl sulphonates, such as sodium dodecyl benzene sulphonate, olefinsulphonates, such as sodium olefin sulphonate in which the olefin group contains 12-22 carbon atoms, higher alkyl sulphoacetates, higher fatty acid esters of 1 ,2-dihydroxy propane sulphonates, and the substantially saturated higher aliphatic acyl amides of lower aliphatic amino carboxylic acid compounds such as those having 12-16 carbon atoms in the fatty acid, alkyl or acyl radicals and the like.Examples of the last mentioned amides are N-lauroyl sarcosine, and the sodium, potassium, and ethanolamine salts of N-lauroyl, N-myristoyl or N-palmitoyl sarcosine, which should be substantially free from soap or similar higher fatty acid material which tends to substantially reduce the effect of these compounds in the compositions of the present invention. The amides are particularly advantageous since they exhibit a prolonged and marked effect in the inhibition of acid formulation in the oral cavity due to carbohydrates breakdown in addition to exerting some reduction in the solubility of tooth enamel in acid solutions.

Another desirable material is a long chain fatty acid sodium monoglyceride sulphonate used alone or in combination with sodium lauryl sulphate.

Other particularly suitable surface-active materials include nonionic agents such as condensates or sorbitan monostearate with approximately 20 moles of ethylene oxide, condensates of ethylene oxide with propylene glycol ("Pluronic" materials) and amphoteric agents such as long chain (alkyl) amino-alkylene alkylated amine derivatives, which are available under the trade-mark "Miranol" such as Miranol C2M.

Cationic surface-active germicides and antibacterial compounds such as di-isobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride, benzyl dimethyl stearyl ammonium chloride, benzyl diethyl stearyl ammonium chloride, tertiary amines having one fatty alkyl group (of from 1218carbon atoms) and two (poly) oxyethylene groups attached to the nitrogen (typically containing a total of from about 2 to 50 ethanoxy groups per molecule) and salts thereof with acids, and compounds of the structure

where R represents a fatty alkyl group containing from about 12 to 18 carbon atoms, and x, y and z total 3 or higher, as well as salts thereof with mineral or organic acids, may also be used. It is preferred to use from about 0.05 to 5% by weight of the foregoing surface-active materials in the dental cream. It is most preferred that the surface-active agent be an anionic material, particularly sodium lauryl sulphate.

The dental cream suitably may also contain a fluorine-containing compound having a beneficial effect on the care and hygiene of the oral cavity, e.g. diminution of enamel solubility in acid and protection of the teeth against decay. Examples thereof include sodium fluoride, stannous fluoride, potassium fluoride, potassium stannous fluoride (Sn F2 KF), sodium hexafluorostannate, stannous chlorofluoride, sodium fluorozirconate, and sodium monofluorophosphate. These materials which disassociate or release fluorine-containing ions in water, suitably may be present in an effective but non-toxic amount, usually within the range of about 0.01 to 1% by weight of the water-soluble fluorine content thereof.

The preferred fluorine-containing compound is sodium monofluorophosphate typically present in an amount of about 0.076 to 7.6 by weight, preferably 0.76%. A mixture of sodium monofluorophosphate and sodium fluoride is also desirable, for instance in weight ratio of about 2:1 or 1:1 based on fluoride, in amounts preferably providing about 1500--1450 ppm soluble fluoride.

Any suitable flavouring or sweetening materials may be employed in formulating a flavour for the composition of the present invention. Examples of suitable flavouring constituents include the flavouring oils, e.g. oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon and orange, as well as methyl salicylate. Suitable sweetening agents include sucrose, lactose, maltose, xylitol, sodium 6-methyl-3,4-dihydro-1 ,2,3-oxathiazine-4-one, sodium cyclamate, perillartine and sodium saccharin. Suitably, flavour and sweetening agents may together comprise from about 0.01 to 5% or more of the compositions of the present invention.

Various other materials may be incorporated in the dental cream. Examples thereof are colouring or whitening agents or dyestuffs, anti-corrosive agents, preservatives, silicones, chlorophylic compounds, ammoniated materials such as urea, diammonium phosphate and mixtures thereof and other constituents.

Whitening agents, such as titanium dioxide, typically in amounts of about 0.52% may be beneficial to the appearance of the dental composition, since upon aging, some discolouration may occur. It is noteworthy that sodium benzoate preservative may assist in reducing syneresis of the dental cream in contact with polyolefin surface, typically when present in an amount of about 0.150.75% by weight preferably about 0.5%.

The adjuvants are incorporated in the compositions of the present invention in amounts which do not substantially adversely affect the properties and characteristics desired and are selected and used in proper amounts depending upon the particular type of composition involved.

Antibacterial agents may also be employed in the oral compositions of the present invention in an amount of about 0.015% by weight. Typical antibacterial agents include: N1-(4-chlorobenzyl)-N5-(2,4-dichlorobenzyl) biguanide; p-chlorophenyl biguanide; 4-chlorobenzylhydryl biguanide; 4-chlorobenzylhydrylguanylurea; N-3-lauroxypropyl-N5-chlorobenzylbiguanide; 1,6-di-chlorophenylbiguanidohexane; 1 ,6-bis-(2-ethylhexylbiguanide) hexane; 1-(lauryldimethylammonium)-8-(p-chlorobenzyldimethylammonium) octane dichloride; 5,6-dichloro-2-guanidinobenzimidazole; Nl-p-chlorophenyl-N5-laurylbiguanide; 5-amino-1,3-bis(2-ethylhexyl)-5-methylhexahydropyrimidine and their non-toxic acid addition salts.

The package into which the dental cream is incorporated may be any polyolefin laminate dental cream tube. For instance, the tube may be as elementary as is described in U.S. patent 3,260,410 to Brandt et al, the disclosure of which is incorporated herein by reference. As described in the example thereof, an aluminium foil base having a thickness of about 0.0013 cm was heated to a temperature of approximately 1770C, and one face of the heated foil was contacted by an extrudable film of a random copolymer of ethylene and acrylic acid (acid content 3+0.5% and melt index 8+1), while the opposite surface thereof had placed thereagainst a film of low density polyethylene.

Using driven rolls a laminated base was obtained in which the copolymer layer was about 6 mils and the polyethylene layer was approximately 5 mils in thickness. The base was then shaped into tubular form and sealed.

After severing the tubular form into tube bodies, the tubes can be packed with the dental cream of the present invention.

Polyolefin laminate dentrifrice tubes containing more intermediate layers may also be successfully used with the dental cream of the present invention without undergoing syneresis. For instance, the multiple layer flexible sheet structure for dental cream tubes described as "Prior Art" in U.S. Patent 4,418,841 to Eckstein may be employed as well as the more crack resistant structures described therein. The disclosure of U.S. Patent 4,418,841 to Eckstein is incorporated herein by reference. In fact, dental creams of the present invention packaged in tubes of sheet material identified as Prior Art A and A-l in U.S. Patent 4,418,841 are very satisfactory and undergo substantially no syneresis. Such tubes A and A-l are comprised of layers as set forth below, in the order of the outermost layer to innermost layer.

A A-l 1.5 mil LDPE 1.5 mil LDPE 2.0 mil Pigmented LDPE 2.0 mill Pigmented LDPE 1.6 mil Paper 1.6 mil Paper 0.7 mil LDPE 2.0 mil LDPE 3.3 mil EAA 1.0 mil OPP 0.7 mil Foil 1.0 mil EAA 2.0 mil EAA 0.7 mil Foil 1.2 mil LDPE 2.0 mil EAA 1.2 mil LDPE 13.0 mil Total 13.0 mil Total In A and A-l the abbreviations have the following meanings: LDPE-Low density polyethylene EAAEthylene acrylic acid OPPOriented polypropylene Mechanically operated dispensers, such as the dispenser for, in particular, pasty substances, described in U.S. Patent 4,437,591 to von Schuckmann, the disclosure of which is incorporated herein by reference, may also be used with the practice of the present invention.The housing of such dispensers is commonly composed of a polyolefin resin such as polypropylene. Thus the housing resin is in essence a layer, the inner surface of which is in contact with dental cream. When the dental cream of the present invention is packaged in such a polypropylene mechanical dispenser, it undergoes substantially no syneresis.

The advantages of the invention are also present when the dental cream is packaged in a flexible sachet having a polyolefin surface, typically of low density or medium density polyethylene.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying examples. All amounts and proportions are by weight except as otherwise indicated.

EXAMPLES 1Aand 1B The dental creams set out in Table 1 below are prepared to creamy consistencies and packed into tubes each of the laminated structures A and A-l, set forth above.

TABLE 1 Parts A B Glycerine 10.000 10.000 Sorbitol (70%) 17.000 17.000 Sodium Carboxymethyl cellulose 0.900 0.900 Sodium Saccharin 0.200 0.200 Tetrasodium pyrophosphate 0.250 0.250 Sodium Monofluorophosphate 0.760 0.760 Sodium Fluoride 0.100 0.100 Benzoic acid 0.250 0.250 Sodium Benzoate 0.500 Deionized water-irradiated 15.646 16.146 Alpha-alumina trihydrate (BACO AF-230) 51.500 51.500 Titanium Dioxide 0.500 0.500 Sodium lauryl sulphate (90%) 1.444 1.444 Flavour 0.950 0.950 pH (20% slurry) 8.2 8.2 After aging for at least 9 weeks at49"C, the dental creams of Examples 1A and 1 B remain creamy in consistency in laminate tubes each of laminate structures A and A-l. Similarly formulated dental creams (Examples 1 C and 1 D) with sodium diacid orthophosphate used to reduce the pH (instead of benzoic acid) quickly separate at room temperature and 49"C in both the tubes of structures A and A-i.

EXAMPLE 2 The dental creams of Examples 1A and 1 B are incorporated into a mechanical dispenser in accordance with U.S. Patent 4,437,591 composed of polypropylene housing. Both dental creams retain their creamy consistency.

EXAMPLE 3 Similar results to those described above for Examples 1 and 2 are observed when: (i) the relative amounts of glycerine and sorbitol (70%) are 6:24 and 18:6; (ii) sodium fluoride is omitted and its amount replaced by water; (iii) the dental creams are packed in laminated tubes in accordance with U.S. Patent 3,260,410; (iv) the dental creams are packed in crack-resistant laminated tubes in accordance with U.S.Patent 4,418,841; (v) the dental creams are packed in flexible sachets of the following structure from outermost to innermost layer; 12.2 microns polyethylene terephthalate 21.3 microns white ethylene acrylic acid 9.0 microns foil 3.3 microns ethylene acrylic acid 25.4 microns medium density polyethylene (vi) BACO AF-230 alpha-alumina trihydrate is replaced by each of Alcoa C-333, Rhone Poulenc SH100, Martinswerk 0S4608 and 0N4608 alpha-alumina trihydrate; (vii) 3.000 parts of calcined alumina replace 3.000 parts of alpha-alumina trihydrate; ; (viii) 10 parts of insoluble sodium metaphosphate replace 10.000 parts of alpha-alumina trihydrate, and (ix) sodium cyclamate replaces sodium saccharin It is understood that the foregoing detailed description is given merely by way of illustration and that variations may be made therein without departing from the spirit of the invention.

Claims (19)

1. A dental cream package wherein the said dental cream is in direct contact with a polyolefin resin package surface, the said dental cream comprising at least about 20% by weight of a liquid vehicle comprising water, glycerine and sorbitol, the weight ratio of glycerine to sorbitol being from about 0.25:1 to about 3:1, a solid vehicle comprising about 0.0510% by weight of gelling agent, about 2075% by weight of a dentally acceptable water-insoluble polishing material, at least a major portion of which is alpha-alumina trihydrate, and benzoic acid to reduce the pH of the dental cream to about 6-8.5.

2. A dental cream package as claimed in Claim 1 in which the weight ratio of glycerine to sorbitol is from about 0.25:1 to about 0.8:1.

3. A dental cream package as claimed in Claim 2 in which the weight ratio of glycerine to sorbitol is from about 0.6:1 to about 0.8:1.

4. A dental cream package as claimed in any one of Claims 1 to 3 in which benzoic acid is present to reduce the pH of the dental cream to about 7.58.5.

5. A dental cream package as claimed in any one of Claims 1 to 4 in which benzoic acid is present in an amount of about 0.150.5%.

6. A dental cream package as claimed in any one of Claims 1 to 5 in which about 0.250.75% by weight of sodium benzoate is present.

7. A dental cream package as claimed in any one of Claims 1 to 6 in which a fluorine-containing compound is present in an amount corresponding to 0.01-1% by weight based on watersoluble fluorine contents.

8. A dental cream package as claimed in Claim 7 in which sodium monofluorophosphate is present.

9. A dental cream package as claimed in any one of Claims 1 to 8 in which a mixture of sodium monofluorophosphate and sodium fluoride is present in a weight ratio of about 2:1 based on fluoride.

10. A dental cream package as claimed in any one of Claims 1 to 9 in which the dental cream provides phosphate ion.

11. A dental cream package as claimed in any one of Claims 1 to 10 in which the dental cream is substantially as specifically described with reference to Examples 1A or 1 B or Example 3.

12. A dental cream package as claimed in any one of Claims 1 to 11 in which the said dental cream is packaged in a plastic laminate tube.

13. A dental cream package as claimed in Claim 12 in which the inner polyolefin resin surface of the said plastic laminate tube is polyethylene.

14. A dental cream package as claimed in Claim 13 in which the said polyethylene is low density polyethylene.

15. A dental cream package as claimed in any one of Claims 1 to 11 in which the said dental cream is packaged in a mechanical dispenser having a housing of polyolefin resin.

16. A dental cream package as claimed in Claim 15 in which the said polyolefin resin of the said housing is polypropylene.

17. A dental cream package as claimed in any one of Claims 1 to 11 in which the said dental cream is packaged in a flexible sachet.

18. A dental cream package as claimed in Claim 17 in which the inner polyolefin resin surface of the said sachet is low density polyethylene or medium density polyethylene.

19. A dental cream package as claimed in Claim 1 substantially as specifically described herein with reference to the accompanying examples.