GB2210558A

GB2210558A - Preventing syneresis in packaged dental cream

Info

Publication number: GB2210558A
Application number: GB8823455A
Authority: GB
Inventors: Robert Lee Mitchell; Gary A Durga
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1987-10-08
Filing date: 1988-10-06
Publication date: 1989-06-14
Anticipated expiration: 2008-10-06
Also published as: CH677074A5; MY103921A; AT395532B; FR2621482A1; DK563788A; GR1000574B; MX169811B; IT8848435A0; PT88697A; AU2349388A; JPH01156908A; PT88697B; GB2210558B; NO174324B; ZA887380B; DK563788D0; CA1327528C; IT1224558B; NO174324C; BE1001410A3

Description

"PACKAGED DENTAL CREAW' This invention relates to a dental cream packaged

in a plastic laminate tube, mechanical dispenserr flexible sachet or the like. In particular, it relates to a dental cream in compatible contact with a polyole fin 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 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 bear 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 2 with dental cream.

Dental creams typically contain a liquid vehicle of water and humectant, a gelling agent solid vehicle and a water-insoluble dental polishing agent. A surface active agent is also generally included. Dental creams composed of such materials wherein the humectant comprises glycerine and sorbitol and the polishing material is an alkaline earth metal salt such as dicalcium phosphate have been successfully packaged in flexible metal toothpaste containers including aluminium tubes which are unlined or WIiich have an internal coating of an epoxy resin lacquer layer. However, it is observed that when such dental creams are differently packaged in containers having an interior polyolefin surface such as plastic laminated dental cream tubes, mechanically operated dental cream dispensers or flexible sachets. that syneresis becomes a problem and liquids separate from solids, rendering the dental cream undesirable.

In earlier commonly assigned patent disclosures additives to prevent dental cream syneresis upon contact with a polyolefin surface have been disclosed for dental creams containing an alkaline earth metal phosphate or alpha-alumina trihydrate polishing agent.

These disclosures are:

U.S. Serial No. 771,378, filed 30 August. 1985,, and U.S. Serial No. 803, 0401 filed 27 November. 1985. which correspond to G.B. Application No. 8620687 Serial No. 2180155 published 25 March, 1987, wherein the antisyneresis additive for an alkaline earth phosphate dental cream or an alpha-alumina trihydrate dental cream is a polyethylene glycol; U.S. Serial No. 808,755, filed 13 December, 1985.

3 wherein the anti-syneresis additive for a dental cream in which the polishing agent is mainly an alkaline.

earth metal phosphate is propylene glycol; U.S. Serial No. 808,756, filed 13 December, 1985, and U.S. Serial No. 922,872, filed 31 October, 1986,, which correspond to G.B. Application No. 8629654 Serial No. 2184018 published 17 June. 1987, wherein the anti syneresis additive for a dental cream in which the polishing agent is mainly an alkaline earth metal phosphate is an alkyl parahydroxybenzoate ester; U.S. Serial No. 821,566, filed 22 January,, 1986,, which corresponds to G. B. Application No. 8701191 Serial No. 2185399 published 22 July. 1987. wherein the anti-syneresis additive for an alpha-alumina trihydrate dental cream is a vegetable oil; U.S. Serial No. 821,567, filed 22 January, 1986, which corresponds to G.B. Application No. 8701190 Serial No. 2186190 published 12 August, 1987, wherein the anti-syneresis additive for an alkaline earth metal phosphate dental cream is a vegetable oil; and U.S. Serial No. 835,014, filed 28 February, 1986, which corresponds to G. B. Application No. 8704684 Serial No. 2187095 published 3 September, 1987, wherein the anti-syneresis addit4ve for a dental cream in which the polishing agent is mainly alpha-alumina trihydrate is benzoic acid.

In each of the foregoing patent disclosures condensates of ethylene oxide with propylene glycol, that is "Pluronic" materials, are generally disclosed as a type of surface-active material which may be present in the several dental creams containing the described particular anti-syneresis additives.

Japanese Public Disclosure No. 75410/85 to Ebine

4 et al (Lion Corporation) describes a dentifrice in which glycerine is the sole humectant or mixed with another humectant, such as sorbitol, but which glycerine is, in any event. present in amount greater than 20% by weight of the dentifrice, since lesser amounts would result in undesirable evaporation of water when the dentifrice is packed in a container having a plastic container body,, at least the barrel portion of which has a water permeability of at least 5 g/m2.day.50u. The high glycerine dentifrice is formulated to avoid evaporation and weight loss in this particular type of container. The disclosure includes a general indication that polymer of ethylene oxide and propylene oxide may be employed as surface-active agent.

U.S. Patent 4,556,553 to Suganuma et al (Lion Corporation) discloses dentifrices containing an aluminium oxide abrasive in a container having an oxygen permeability of at least 3 cc/m2.day.atm wherein antiseptic properties are improved by the presence of polyhydric alcohol, including mixture of sorbitol and glycerine. There is a general disclosure that condensates of ethylene oxide with propylene oxide may be used as a surface-active agent in the aluminium oxide dentifrices. Some dentifrice samples are described for comparative purposes which contain dicalcium phosphate with sodium lauryl sulphate as the sole surface active agent.

Japanese Public Disclosure 86526/78 to Naganuma et al (Lion Dentifrice Company) discloses that liquidsolid separation in toothpaste containing an anionic surfactant and a polyoxyethylene block copolymer type surfactant (that is, a "Pluronic" surfactant) can be overcome by employing a binder or gelling agent of at least one of hydroxyethyl cellulose- and/or xanthan gum rather than carrageenan, gum tragacanth, sodium carboxymethyl cellulose, poly(sodium, acrylate) or guar gum. The toothpastes described contain a humectant such as glycerin, sorbitol, propylene glycol or polyethylene glycol. The only mixtures of humectants described in specific formulations including those which evince separation when a gelling agent other than hydroxyethyl cellulose or xanthan is employed, contain glycerine and propylene glycol.

U.S. Patent 4,353,890 to Scott (Colgate-Palmolive Company) discloses toothpastes containing carrageenan gelling agent which is stabilized by microwave radia- 1,5 tion to maintain viscosity. A dicalcium phosphate toothpaste containing such stabilized carrageenan with a mixed humectant of 4.5% by weight of glycerol and 17.5% by weight of sorbitol is exemplified and indicated to be subjected to storage tests, including when packaged in containers having body portions of polyethylene. The detergent or surface-active agent employed in the exemplified toothpaste is sodium lauryl sulphate. The patent includes a general disclosure "Pluronics (Registered Trade Mark)" as detercrents.

It is an advantage of this invention that phase separation of a dental cream packaged in contact with a polyolefin material which would undergo phase separa tion but for the presence of an additive which over comes syneresis, is substantially prevented.

According to the present invention there is provided a packaged dental cream wherein the said dental cream is in direct contact with a low or medium density polyethylene or polypropylene surface.

6 syneresis occurring in the said dental cream due to the said direct contact when the said dental cream consists essentially of as ingredients about 20-75% by weight of a liquid vehicle consisting essentially of about 10-50% by weight of water,, about 5.0-15% by weight of glycerine and sorbitol, the amount of glycerine and sorbitol together being about 15-50% by weight,, the weight ratio of glycerine to sorbitol being from about 0. 25:1 to about 1: 1, about 0. 05-10% by weight of a dental cream gelling agent selected from the group consisting of Irish Moss, gum tragacanth, sodium carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium alginate, guar gum, starch, xanthan and iotacarrageenan, and about 20-75% by weight of a dentally acceptable water-insoluble calcium or magnesium alkaline earth metal salt polishing agent; the said dental cream consisting essentially of the said ingredients and containing as the sole additive to prevent syneresis in the said dental cream upon the said direct contact, about 0.1-5% by weight of a nonionic polyoxyethylene-polyoxypropyl ene block copolymer.

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 dental cream of the present invention comprise chiefly water, glycerine and sorbitol. The total liquid vehicle amounts to about 20-75% by weight of the formulation. The gelling agent in the dental creams is a natural or synthetic gum or gumlike material, particularly, e.g. Irish Moss (carra geenan), gum tragacanth, sodium carboxymethylcellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium 7 alginate, guar gum, starch, xanthan or iota-carragee nan, including mixtures thereof. -Irish Moss,, sodium carboxymethyl cellulose, and iota-carrageenanf including mixtures thereof are compatible particularly and are preferred gelling agents. The gum content is in an amount of about 0.05-10% and preferably about 0.5-5% by weight of the formulation.

Water is incorporated into the dental cream in amount of about 10-50% by weight, preferably about 15 lo 35%. Glycerine and sorbitol together generally comprise about 15-50% by weight, preferably about 20 35% of the dental cream. with the amount of glycerine being about 5.0-15% by weight and the weight ratio of glycerine to sorbitol being from about 0.25:1 toabout is 1:1, typically from about 0.25:1 to about 0,8:1 and preferably from about 0.25:1 to about 0.6:1. It is preferred to use about 6-10% by weight of glycerine and about 17-24% by weight of sorbitol. 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 alkaline earth metal salt polishing agent is present in the dentalcream in amount of about 20-75% by weight, preferably about 35-60%. Typical salts include dicalcium phosphate dihydrater anhydrous dicalcium phosphatei calcium carbonate, tricalcium phosphate, calcium pyrophosphate, dimagnesium phosphate trihydrate and magnesium carbonate including mixtures thereof. Most preferably, calcium salt, particularly dicalcium phosphate dihydrate or mixtures of dicalcium phosphate dihydrate and anhydrous dicalcium phosphatel is present.

In addition to the alkaline earth metal salt 8 polishing agent, additional polishing agent such as hydrated alumina and calcined alumina may be present, for instance in a weight ratio of alkaline earth metal salt to alumina material of about 2. 5:1 to about 4:1 F 5 the total amount of polishing material in the dental cream being about 25-75% by weight. The single material employed in accordance with the present invention to prevent syneresis when the dental cream is in direct contact with a low or medium 10 density polyethylene or polypropylene is a nonionic polyoxyethylene-polyoxypropylene block cbolymer. The block copolymer is also effective in the dental cream as a surface-active agent. It is pres.ent in amount of about 0.1-5% by weight, preferably about 0.5-3%. is The nonionic surface-active agent employed in the present invention is a block copolymer containing polyoxyethylene and polyoxypropylene. Such block copolymers are available from Wyandotte Chemicals Corporation under the trademark "Pluronic". They may be liquid, paste or solid and are generally chemically defined in terms of the molecular weight of the polyoxypropylene hydrophobic moiety and the percent by weight of the polyoxyethylene hydrophilic moiety. The following block copolymers are available from Wyandotte:

Pluronic Physical Mol. Wt.

Number Character Hydrophil hydrophobe L121 Liquid 10 4000 L101 Liquid 10 3250 L 81 Liquid 10 2250 L 61 Liquid 10 1750 L 31 Liquid 10 950 9 L122 Liquid 20 4000 L 92 Liquid 20 2750 L 72 Liquid 20 2050 L 52 Liquid 20 1750 L 42 Liquid 20 1200 P123 Paste 30 4000 P103 Paste 30 3250 L 63 Liquid 30 1750 L 43 Liquid 30 1200 P104 Paste 40 3250 P 94 Paste 40 2750 P 84 Paste 40 2250 P 64 Liquid 40 1750 P 44 Liquid 40 1200 P105 Paste 50 3250 P 85 Paste 50 2250 P 75 Paste 50 2050 P 65 Paste 50 1750 P 35 Liquid 50 950 F127 Solid 7n 4000 F 87 Solid 70 2250 P 77 solid 70 2050 F108 solid 80 3250 F 98 Solid 80 2750 F 88 Solid 80 2250 F 68 Solid 80 1750 F 38 Solid 80 950 The preferred nonionic block copolymers are solid (or flake) materials and the most preferred are Pluronic F 108 (80% polyoxyethylene: 3250 molecular weight poly oxypropylene) and F-87 (70% polyoxyethylene: 2250 molecular weight polyoxypropylene)# F-127 (70% polyoxy ethylene: 4000 molecular weight polyoxypropylene) and L-72 (20% polyoxyethylene: 2050 molecular weight poly oxypropylene).

Since the nonionic block copolymer anti-syneresis agent does not provide substantial foam to the dental cream, an anionic surface-active agent may also be provided for its foaming character and in order to enhance detergency. The surface-active agents may achieve increased prophylactic 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 cosmeti cally acceptable. Suitable anionic surface-active materials 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 dodecy! benzene sulphonate, olefin sulphonates, such as sodium olefin sulphonate in which the olefin group contains 12-22 carbon atoms, higher alkyl sulpho acetatesi higher fatty acid ester 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 to 16 carbon atoms in the fatty acidi 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-lauroyly N-myristoyl or Npalmitoyl sarcosine, which should be substantially free from soap or similar higher fatty acid material which tends to subs tantia 1 ly-reduce the effect of these compounds in compositions of the present invention. The amides are particularly advantageous since they exhibit a prolonged and marked effect in the inhibition of acid formation in the oral cavity due to carbohydrate breakdown in addition to exerting some reduc- tion 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. It is preferred to use about 0.2-5% by weight of total surface-active agent typically about 1-3%. when anionic surface-active agent is present.

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 fluoridei potassium fluoride. potassium stannous fluoride (SnP2.KF), sodium hexafluorostannate, stannous chlorofluoride. sodium fluorozirconate and sodium monofluorophosphate. These materials which disassociate or release fluorinecontaining ions in wateri 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 12 0.76%. A mixture of sodium monof luorophosphate and sodium fluoride is also desirable,- for instance in a weight ratio of about 2:1 based on fluoride.

Any suitable flavouring or sweetening materials may be employed in formulating a flavour for the composition of the present invention. Examples of su itable flavouring constituents include the flavouring oils, e.g. oils of spearmint. peppermint, wintergreen. sassafras, clove, sage. eucalyptus, 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 agen ts or dyestuffs, preservatives such as sodium benzoate. anti-corrosive agents, 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 0.5-2%, may be beneficial to the appearance of the dental composition. since upon aging, some discolouration may occur.

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 13 oral compositions of the present invention in an amount of about 0.01-5% by weight. Typical antibacterial agents include:

Nl-(4-chlorobenzyl)-NS-(2r4-dichlorobenzyl) biguanide; p-chlorophenyl biguanide; 4-chlorobenzhydryl biguanide; 4-chlorobenzhydrylguanylurea; N-3-lauroxypropyl-N5_chlorobenzylbiguanide; l16-dichlorophenylbiguanidohexane; 1,6-bis-(2-ethylhexylbiguanido) hexane; 1 -(lauryldimethy l ammonium) -8- (p -chlorobenzyldimethyl-ammonium) octane dichloride; 516-dichloro-2-guanidinobenzimidazole; Ni-p-chlorophenyl-N5_laurylbiguanide; 5-amino-1 13-bis(2-ethylhexyl)-5-methylhexahydropyrimidine and their non- toxic acid addition salts.

There may be employed also various calcium and magnesium ion suppression agents for adjustment of physical properties of the compositions. Suitable agents are the water- soluble inorganic polyphosphate salts, such as tetrasodium pyrophosphate or disodium diacid pyrophosphate, with the partially neutralized or acid polyphosphate preferred. Other suitable agents are the alkali metal, preferably sodium. salts of citric acid. -In general, such compounds will be a minor amount or proportion of the formulation. The precise amount will vary depending upon the specific formulation, such as the physical characteristics of the dental cream, but will usually be from about 0.1% to about 3% by weight.

The dental creams should have a pH practicable for use. A pH range of 5 to 10 is particularly desirable.

14 The reference to the pH is meant to be the pH deter mination directly on the dental cream. If desired.

materials such as citric acid may be added to adjust the pH to say 6 or 7.

The package into which the dental cream is incor porated 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 on the opposite surface thereof there was 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 c-an be packed with the dental cream of the present invention without the dental cream undergoing syneresis.

Polyolefin laminate dentrifrice tubes containing more intermediate layersmay 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 4.418f841 to Eckstein is incorporated herein by reference. In fact, dental creams of the present invention packed in tubes of sheet material identified as Prior Art A and A-1 in U.S. Patent

4.418,841 are very satisfactory and undergo substan tially no syneresis. Such tubes A and A-1 are comprised of layers as set forth below, in the order of outermost layer to inner most layer.

A A-1 1.5 mil LDPE 1.5 mil LDPE 2.0 mil Pigmented LDPE 2.0 mil 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-1 the abbreviations have the following meanings:

LDPE low density pc"-,rethylene A EAA ethylene acrylic acid OPP oriented polypropylene.

Medium density polyethylene may replace low density polyethylene. In a dental cream sachet package 30 medium density polyethylene is preferred.

Mechanically operated dispensers, such as the dispenser for, in particular, pasty substances, described in U.S. Patent 4.437.591 to von Schuckmann, 16 the disclosure of which is incorporated herein by reference, may also be used in the practice of the present invention. The housing of such dispensers is commonly composed of a polyolefin resin such as poly propylene. 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 mechani cal dispenser, it undergoes substantially no syneresis.

The following properties given in Table 1 below are typical of low and medium density polyethylene:

TABLE 1

Low Density Medium Density Polyethylene Polyethylene Transparent Transparent to to Clarity Translucent Translucent Yield sq.in/1b./0.001-in 30r000 29F500 sq.cm/kg/0.001-cm 1,085j000 1r065,000 Specific 0.910-0.925 0.926-0.940 gravity Tensile strength lb./sq.in 1f000-3f500 2j000-5f000 ASTM D-882 kPa 6j900-24,,15013f800-34,500 Elongation 225-600 225-500 ASTM D-882 17 TABLE 1 (continued) Low Density Medium Density Polyethylene Polyethylene Impact Strength 7-11 4-6 (kg-cm) Tear strength gm/0.001 in. 100-400 50-300 ASTM D-1922 Elmendorf gm/0.001 cm. 250-1j000 125-750 Elmendorf Heat seal range OF 250-350 260-310 oc 120-175 125-155 WTR gm/24 hr/100 sq/in. 1.2 0.5-1.0 90% RH at 100 0 F ASTM E-96 gm/24 hr/100 sq.cm. 7.74 3.23-6.45 at 370C Gas transmission 02-ASTM D-1434 cc/0.001-in./100 sq.in./ 250-840 165-335 24 hr. at ATM 730F+O% RH cc/0.001 cm/100 sq.cm.! 150-515 100-205 24 hr. at ATM 22.77OC+O%RH Gas transmission C02-ASTM D-1434 cc/0.001-in/100 sq.in./ 495-5,000 500-840 24 hr. at ATM 73o+0% RH cc/0.001-cm/100 sq.cm./ 300-3j050 305-515 24 hr. at ATM 22.77c)C+O%RH 18 TABLE 1 (continued) Low Density Medium Density Polyethylene Polyethylene Resistance to Varies Good grease and oils Maximum Use OF 150 180-220 Temperature OC 65.5 82-105 Dimension change None None at high RH (%) Machine performance Fair Fair Printability Good if Good if treated treated Heat shrinkable Some types Some types Typical of polypropylene grades which may be employed particularly as dispenser hou.sing for the dental cream are those supplied by Shell Chemical Company as Polypropylene DP SA03 and Polypropylene DP 25 SA03S. These controlled rheology products combine the processibility of 12 melt flow grades with higher practical impact strength (as measured by falling weight testing).

They were designed for fast processing in multi30 cavity molds.

Polypropylene grades DP SA03 and DP 5A03S have the following typical properties as set out in Table 2 below.

19 TABLE 2

Traditional ASTM Units SI Units Test Melt flow 12 g/10 min 12 g/10 min D 12381 I?ensity at 230C 0.905 g/cc 0.905 glcc D 1505 Tensile yield strengthy at 5.0 cm/min 5000 psi 34 MPa D 6382 Yield elongationt at 5.0 cm/min 9% 9% D 6382 1% Secant modulus, at 0.5 cm/min 190j000 psi 1300 MPa D 6382 Flexural modulus, at 0.13 cm/min, cm span 200.000 psi 1375 MPa D 79A2 Notched Ixod impact strength, at 730F/230C 0.5 ft-1b/in 26 J/m D 2562 at OOFI-180C 0.3 ft-1b/in 15 i/m D 2562 Hardness, Rockwell R92 R92 D 785 Heat deflection temp., at 66 psi/455 kPA 220F 1040C D 648 Vicat softening temp. 305oF 1520C D 1525 Notes on Table 2 1 Condition 23012.16 2 ASTM Type I specimen, 0.32 cm thick (injection molded).

The advantages of the invention are also present when the dental cream is packed 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 1A and 1B The following dental creams having the composi- tions given in Table 3 are prepared to creamy consistencies and packed into tubes of each of laminated structures A and A-1, set forth above..

TABLE 3

Example 1A IB

Glycerine (99.3%) 10.00 10.00 Sorbitol (70%) 17.00 17.00 Sodium Carboxymethylcellulose 0.95 0.95 Sodium Saccharin 0.20 0.20 Tetrasodium Pyrophosphate 0.25 0.25 Sodium Monofluorophosphate 0.76 0.76 Dicalcium, Phosphate Dihydrate 48.76- 48.76 Sodium Lauryl Sulphate 1.10 1.10 Flavour 0.89 0.89 2. Pluronic F-108 0.50 - Water Q.S. to Q.S. to 100.00 100.00 The dental cream of Example 1B begins to undergo syneresis and phase separation after aging for 8-10 days at room temperature. The dental cream of Example 1A remains stable against such phase separation when aged at room temperature for periods exceeding one 21 year.

EXAMPLE 2

The dental creams of Examples 1A and 1B are incorporated into a mechanical dispenser in accordance with U.S. Patent 4.437,,591 composed of polypropylene housing. The dental cream of Example 1A retains its creamy consistency while the dentifrice of Example 1B separates into liquid and solid phases.

Similar results to those described in the above Examples are observed when:

(i) Each of Pluronic F-127 and F-87 replace Pluronic F-108; (ii) Pluronic L-72 replaces Pluronic F-108; (iii) Pluronic P-84 replaces Pluronic F-108; 15 (iv) the comparative amounts of glycerine and sorbitol (70%) are: 5:20 and 12:15; (v) Each of Irish Moss and iota-carrageenan replace sodium carboxymethyl cellulose; (vi) The dental creams are packed in laminated tubes in accordance with U.S. Patent 3,260,410; (vii) The dental creams are packed in crack resistant laminated tubes in accordance with U.S. Patent 4 r 418,,8 41 (viii) The dental cr-ams 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; and (ix) Mixture of 0.3 parts of sodium carboxymethyl cellulose and 0.6 parts of iota- carrageenan replace of 22 sodium carboxymethyl cellulose as the sole gelling material. 1 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.

is 1 A- 23

Claims

1. A packaged dental cream wherein the said dental cream is in direct contact with a low or medium density polyethylene or polypropylene surface, wherein syneresis occurs in the said dental cream due to the said direct contact when the said dental cream consists essentially of as ingredients about 20-75% by weight of the said dental cream of a liquid vehicle consisting of sorbitol, about 10-50% by weight of the said dental cream of water, and about 5.0-15% by weight of the said dental cream of glycerine, the amount of glycerine and sorbitol together being about 15-50% by weight of the is said dental cream, the weight ratio of glycerine to sorbitol being from about 0.25:1 to about 1:1, about 0.0510% by weight of the said dental cream of a dental cream gelling agent selected from the group consisting of Irish Moss, gum tragacanth, sodium carboxymethyl 20' cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium alginate, guar gumt starch, xanthan and iota carrageenan, and about 2075% by weight of the said dental cream of a dentally acceptable waterinsoluble calcium or maanesium alkaline earth metal salt polishing agent; the said dental cream consisting essentially of the said ingredients and as the sole additive to prevent syneresis in the said dental cream upon the said direct contact. about 0.1-5% by weight of the said dental cream of a nonionic polyoxyethylene- polyoxypropylene block copolymer.

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

24

3. A packaged dental cream as claimed in Claim 1 or Claim 2 in which the said block copolymer is a solid material.

4. A packaged dental cream as claimed in Claim 1 2 or 3 in which the said block copolymer has. about an 80% by weight hydrophil polyoxyethylene content and a hydrophobe polyoxypropylene molecular weight of about 3250.

5. A packaged dental cream as claimed in any one of Claims 1 to 4 in which the said gelling agent is sodium carboxymethyl cellulose. present in 'an amount of about 0.5-5% by weight.

6. A packaged dental cream as claimed in any one of Claims 1 to 5 in which the said water-insoluble alkaline earth metal salt is a calcium salt.

7. A dental cream as claimed in Claim 6 in which the said calcium salt is dicalcium phosphate dihydrate.

8. A packaged dental cream as claimed in any one of Claims 1 to 7 in which the said dental cream is packaged in a plastic laminate tube the inner surface of which is low density polyethylene.

9. A packaged dental cream as claimed in any one of Claims 1 to 7 in which the said dental cream is packaged in a mechanical dispenser having a housing of polypropylene resin.

10. A packaged dental cream as claimed in any one of Claims 1 to 7 in which the said dental cream is packaged in a flexible sachet, the inner surface of which is low density polyethylene or medium density polyethylene.

11. A packaged dental cream as claimed in Claim 1 substantially as specifically described herein with reference to the examples.

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