ZA200500218B

ZA200500218B - Aerosol dentrifice formulation

Info

Publication number: ZA200500218B
Application number: ZA200500218A
Authority: ZA
Inventors: Peter Frost
Original assignee: Glaxo Group Ltd
Priority date: 2002-07-23
Filing date: 2006-01-10
Publication date: 2006-03-29
Also published as: GB0217078D0

Description

XY AEROSOL DENTIFRIC'E FORMULATION

This invention relates to dentifrice forrmulations, in particular to a dentifrice formulation that can be stored in a pressurised container from which it can be dispensed onto a toothbrush as a stable and controllable foa m.

Dentifrices are commonly provided as a paste, i.e. a toothpaste, in a collapsible container from which they can be extruded. it is also known to provide a dentifrice formulation as a foam, e.g. as disclosed in DE-A—100 08 834, DE-A-100 08 836 and DE- A-100 08 837. Such formulations generally comprise a fluid mixture containing one or more abrasive, thickener, flavour etc. together with a propellant, normally a liquefied gas with a boiling point below ambient temperature to «rive the formulation out of its container and to expand to foam the formulation. The propellant in these prior art formulations will produce a post-foaming effect.

With this type of formulation it is particularly important to provide a foaming dentifrice that is both practical in use but also gEves an immediate visual impact upon dispensing. Japanese Patent Application No.51-1 2593B discloses a dual phase oil-in- water emulsion formulation for a rapidly collapsing foam aerosol product. The formulation comprises a base agent and a mixed propellant comprising 70-95 wt% dimethylether (DME) and 30-5 wt% water insoluble liquified gas s uch as a flurocarbon, liquid petroleum, vinyl chloride and methyl chloride. This propellant system is important for products that require a rapid collapsing foam like nail polish or hair spray.

With aerosol dentifrice formulations it is vesry important to control the production and expansion of foam so that it can be controlled, particularly onto a small surface area toothbrush head. Also, the post-drooling effect on and around the actuator suffered by many aerosol products can lead to unattractive pr<oduct that becomes unacceptable to use. lt is important therefore that the product must not expand significantly further once dispensed onto a toothbrush or suffer from post—d rooling effects. With this control and aesthetic appeal the product will be both pleasant an«d acceptable to the user.

Dentifrice formulations usually contain a higra proportion of water and many of the more commonly used propellants, eg, hydrocarbon psropellants, are not very miscible with . water making the formulation of an acceptable foam#ing dentifrice product a challenge for those skilled in the art. As a result, many propellants will not provide acceptable foaming . dentifrice formulations, particularly those formulations that are single phase water based.

~ | WO 2004/009049 PCT/GB2003/003150

W Therefore it is an object of the present inventio n to provide a foaming dentifrice formulation with a suitable propellant system that produces a very stable foam and avoids all of the above mentioned problems. . The word foam in the text means a viscous liquid material that includes a large numbrer of small bubbles of vapour of a propellant dispersed therein. . According to this invention an aerosol dentifrice formulation is provided comprising water, a particulate abrasive and a propellant, characterised in that the propellant comprises 2-8 wt% of a non-hydrocarbon and 2-6 wt% of" a hydrocarbon propellant.

In a further aspect of the invention there is provided an aerosol dentifrice formu lation being a fluid mixture, comprising water, & liquified gas propellant and a particeilate abrasive, characterised in that the particulate abrasive comprises 1-10% by weight of the mixture, has a particle size in the range 5-40 microns and comprises a combi nation of a more hard and a less hard abrasive.

A third aspect of the invention provides an aeroso | dentifrice comprising water, a particulate abrasive and a liquefied gas propellant, characterised in that the propellant comprises 2-8 wt% of a non-hydrocarbon and 2-6 wt% of a hydrocarbon propellant, the particulate abrasive comprising 1-10% by weight of the mixture, has a particle size in the range 5-40 microns and comprises a combination of a more hard and a less hard abrasive.

Suitable liquified gas propellants include non-hydreocarbon and hydrocarbon propel lants. These propellants are well known to those sk.illed in the art of aerosol formulation.

Suitable non-hydrocarbon propellants include dimesthylether (DME), chlorofluorocarbon (CFC) hydrofluorocarbon (HFC), hydrochlorofiuorocarbon (HCFC) such a s nitrogen, carbon dioxide, nitrous oxide and compr-essed air. A preferred non- hydrocarbon propellant is DME. DME is useful as a propesllant because soluble in water based products.

Suitable hydrocarbon propellants generate a rang-e of pressures of ca.16-105 psi.

Many propellants are known which can achieve this, suitably a commercial product “Butane 30" comprising a mixture of n-butane, i-proparie and n-propane. Experiments have shown that when the dentifrice formulation comprises a mixture of hydrocarbon : propellant such as n-butane and non-hydrocarbon propellant DME an optimised product is achieveed that has a particularly stable foam without any significant expansion or . collapsiing of the foam.

Suitable liquified hydrocarbon propellants include csne or more Cj to Cs hydrocarbon (HC) such as propane, n-butane or butane 22.

N WO 2004/009049 PCT/GB2003/003150

Ne Typically a maximum total of 8 wt% propella: nt is used, more preferably 5 wt%.

Preferably the dentifrice formulation of the present imvention may comprise between 2-5 wt% of such a liquefied gas propellant. . The formulation is normally stored in a conta iner provided with a release valve, under a pressure corresponding to the vapour press ure of the liquefied propellant at the . storage temperature, and on opening the valve the formulation is expelled as a foam, e.g. onto a toothbrush head.

Typically the container may be provided wilith an actuator device by means of which the valve can be opened and the flow of formulation directed.

The abrasive typically comprises 1-10% by weight of the total mixture and has a particle size in the range of between 5-40 microns. Preferably the formulation comprises 9 wt% or less, e.g. 3-7 wt% abrasive, especially 4.5-6 wt%, typically ca. 5 wt%. The abrasive particle size is in the range of 5-40 microns, preferably 30 microns or less, more preferably 10 microns or less. Suitably a mixture of at least one less hard and at least one more hard particulate abrasive is used, typically im a proportion more hard: less hard in the range 1:1-5, suitably in the range 1:2.5-3.5. Su itably the abrasive material may be a silica or a combination of silicas. Less hard and mores hard abrasives can also be called soft and hard abrasives and this will refer specifically to the hardness of the abrasive particle. Suitable silicas include those known as Zeoderit 124™ (hard) and Zeodent 623™ (soft). The proportion and particle size of the abrasive are found to optimise the combination of suitability for flow of the formulation oust through the valve and effective tooth cleaning.

The formulation preferably also contains one or ranore of the following.

One or more humectant, typically in a proportior of 25-75 wt%, preferably 45-55 wt%, especially 50+2 wt%. Humectants are added to psrotect the formulation from drying out and to provide consistency and protection against cold. Suitable humectants include sorbitol and glycerol. Suitably a mixture of sorbitol and glycerol may be used eg. in a sorbitol:glycerol ratio in the range 1:1.5 ~ 1.5:1. Othew humectants that may be used include xylitol, mannitol, 1,2-propylene glycol or mixtures of these polyols.

One or more slurrying/suspending agent, typicadly in a proportion of 1-5 wit%, preferably 2-3 wt%. A preferred slurrying agent is polyethylene glycol, e.g. of molecular ' weight in the range 200 - 800, typically ca. 300.

One or more surfactant. Typically a surfactant may be used as a foaming agent : as foaming is one property of a surfactant. In this respect & surfactant is sometimes called a foaming agent. Suitable surfactants include anionic surfactants such as a sodium alkyl sulphate with a 12-18 carbon atoms in the alkyl chain, such as sodium lauryl sulphate. Zwitterionic, ampholytic and non-ionic surfactants may also be used. A mixture of surfactants may be used. Suitably the surfactant may cormprise 0.1-3.0 wt% of the formulation, preferably 1-2 wt%. . One or more thickening agent. Typically a thickening agent will add body to the foam. Typical thickening agents include hydroxypropylmethyicellulose (HPMC),

A hydtrxyrethylcellulose (HEC) and hydroxymethylcellulose (HIMC) and the acrylic polymer

Carbopol. Preferred thickening agents include xanthan gum which is a polysaccharide and/or a thickening silica, Zeodent 163. Typically the thickeming agent may comprise 0.1- 4.0 wt%% of the formulation, typically 0.2-3.0 wt%. It is found that use of xanthan gum and

Zeoderst 163 can lead to a creamier foam with improved flow” and texture characteristics.

One or more pH regulator, preferably to maintain the pH at 6.0-10.0, especially at ca. pH 8.0. Such a pH is found suitable to avoid corrosion of the tin plate, aluminum or containers that may be lacquered that are commonly used for containing such formulations. A suitable pH regulator is sodium hydroxide.

One or more other excipent such as a sweetener, Colour, preservative, flavours, dyes etc, typically comprising up to ca. 2 wt% of the formulation.

Such compositions of the present invention may also comprise other active agents conventionally used in dentifrice compositions, for instance: an antimicrobial agent, anti-plaque agent such as chlorhexidine or triclosan; anti-calculus agent such as a tetra- or a di-alkali metal pyrophosphate salt, or a mixture thereof, an alkali metal tripolyphosphate salt or an azacycloheptane diphosphonate salt; an anti- sensitivity agent that acts as a nerve depolariser, tubule occluder or mineralizer. These agents include e.g. strontium acetate, strontium chloride o»r a potassium salt such as potassium nitrate, potassium chloride or potassium citrate; remineralisation agent, a whitening agent such as tetra- or a di-alkali metal pyrophosphate or phosphate salts or peroxide=s, vitamins, fluoride, e.g. sodium fluoride, typically ccomprising up to ca. 0.5 wi% of the Formulation. Such agents will be included at leveels to provide the desired therapeutic effect.

Many other examples of materials of these types are lxnown in the state of the art, e.g. in D'E-A-100 08 837, the content of which is incorporate«d herein by way of example only. . Im order for the formulation to be a fluid mixture, the rermainder of the formulation comprisexs water, typically the formulation comprises ca. 25-50 wi% water, preferably 30- ‘ 40 wt% of the formulation.

A typical formulation according to this invention therefore comprises: one or more humectart 45-55 wt%, slurrying agent 2-3 wt%, surfactant 1—2 wt%, abrasives 3-7 wt%,

J preferably 3-5 wt %, thickening agent 0.2-0.5 wt%, flavour, active and swe-etener 0-2 wt%,

PH adjuste rif necessary to provide pH of 8.5+/- 0.2, water 30-40 wt % preferably 35 +/- 1 wt%. This fluid formulation which is also known as the intermediates formulation is . preferably charged into a metal or plastic container with a dispensing valve, at a proportion of 95-97 wt% with 3-5 wt% propellant providing a pressure of between 25-70, . preferably «10-60 psi.

The- preferred materials and their proportions described above alsso contribute to improved flow and handling of the formulation.

The following observations in the finished product were noted: which foam,no slightly expanding expanding collapses | expansion | expanding | foam foam instantly or foam collapse

A “very slightly expanding foam” can be defined as a foam that when dis pensed onto a toothbrush head may show a small but insignificant expansion.

A typical process for making the formulation of this invention may involve thes steps of: 1. Adding a suitable quantity of water to a mixing vessel. 2. Adding sweetener and active to the water and agitating until dissolved or suspended. 3. Adding the humectant and agitating until homogeneous. 4. Sieving the abrasive to break up any lumps. A 500 micron sie=ve is generally suitable. 5. Slowly adding the abrasive to the mixture while mixing. 6. Slurrying the thickening agent and slurrying agent and add t o the mixture, agitate until homogeneous. , 7. Mixing, optionally transferring to a mixer. 8. Slurrying the flavour, dye and foaming agent and adding to thee mixture, mixing until homogeneous. 9. Adjusting the pH and 10. Mixing until homogeneous.

i WO 2004/009049 PCT/GB2003/003150

WW This fluid mixture may then be charged into suitable valved containers together with a suitable quantity of propellant.

The formulation may be used in a generally conventional manner involving opening the valve of the container to allow the internal pressure to expel the formulation onto a toothbrush. The invention also provides a valved container containing a formulation as described above.

The invention will now be described by way of examples.

Example 1

A dentifice formulation was prepared having the following composition:

Function Component wt% Humectant Sorbitol 70% non-crystallizing 28.000

Humectant Glycerin 22.00

Suspending agent PEG 6 2.500

Foaming agent Empicol 0303 30% solution 5.000

Sweetener Sodium saccharin 0.300

Active Sodium fluoride 0.306

Flavour Flavour 1.000

Abrasive (hard) Zeodent 124+ 1.330

Abrasive (soft) Zeodent 623% 3.670

Thickener Xanthan (Keltrol F) 0.250 pH adjuster 35% NaOH solution 0.250

Dye Dye 0.003

Water to 100.000

Propellant Butane 2.000

Propellant DME 3.000 +Zeodent 124 and Zeoent 623 are trade names of Huber Corporation, USA : 35

A “WO 2004/009049 PCT/GB2003/003150

Example 2

A dentifice formulation was prepared having the following composition:

Function Component wt%

Humectant Sorbitol 70% non-crystallizing 28.000

Humectant Glycerin 22.00

Suspending agent PEG 6 2.500

Foaming agent Empicol 0303 30% solution 5.000

Sweetener Sodium saccharin 0.300

Active Sodium fluoride 0.306

Flavour Flavour 1.000

Abrasive (hard) Zeodent 124 1.330

Abrasive (soft) Zeodent 623 3.670

Thi ckener Zeodent 163 3.000 pH adjuster 35% NaOH solution 0.250

Dye Dye 0.003

Water to 100.000

Pro pellant Butane 3.000

Pro pellant DME 2.000 *Zeodent 124 and Zeoent 623 and Zeodent 163 are trade names of Huber Corporation,

USA

Example 3

A dentifice formulation was prepared having the following compositiors:

Function Component wt . Humectant Sorbitol 70% non-crystallizing 28.000

Hunmectant Glycerin 22.00 : Suspending agent PEG 6 2.500

Foarming agent Empicol 0303 solid 1.500

Sweetener Sodium saccharin 0.300

>

Active Sodium fluoride 0.306

Flavour Flavour 1.000

Abrasive (hard) Zeodent 124 1.330 ) Abrasive (soft) Zeodent 623 3.670

Thickener Zeodent 163 3.000 i Thickener Xanthan (Keltrol F) 0.250

Dye Dye 0.003

Water to 100.000

Propellant Butane 3.000

Propellant DME 2.000 *Zeodent 124 and Zeoent 623 and Zeodent 163 are trade names of Huber Corporation,

USA

This fluid formulatiom was made by a process as described above, involving 1. Adding a suitable quantity of water to a mixing vessel. 2. Adding sweetener and active to the water, mixing until dissolved using a circullar Heidolph paddle stirrer. 3. Adding the glycerol and sorbitol to the batch, mixing unti 1 dissolved using a circular paddle stirrer on the Heidolph. 4, Sieving the abrasive to break up any lumps. A 500 microm sieve is generally suitable. 5. Slowly adding the abrasive to the mixture, mixing using aa circular paddle stirrer on the Heidolph. 6. Slurrying the thickening agent and slurrying agent and acd to the mixture, agitate until homogeneous. 7. Transferring to an Ultra Turrux mixer and mixing for 5 mirutes. 8. Slurrying the flavour and foaming agent and adding to the mixture, mixing until homogeneous with a circular paddle stirrer on the Hesidolph. 9. Adjussting the pH to pH 8 (+/- 0.5) using the NaOH. 10. Mixing until homogeneous on the Heidolph.

This fluid mixture was charged into valved containers together wilith the propellant in a 95:5 or 97:3 w/w ratio.

Claims

J CLAIMS . 5 1. An aerosol dentifrice formulation comprising wrater, a particulate abrasive and a propellant, characterised in that the propellart comprises 2-8 wt% of a non- - hydrocarbon and 2-6 wt% of a hydrocarbon prope llant.
2. An aerosol dentifrice according to claim 1 wherein the non-hydrocarbon propellant comprises dimethylether (DME), a chlorofluorocaxrbon (CFC), a hydrofluorocarbon (HFC) or a hydrochlorofluorocarbon (HCFC), nitrogen, carbon dioxide, nitrous oxide or compressed air.
3. An aerosol dentifrice according to claim 2 wherein the non-hydrocarbon propellant comprises dimethylether (DME).
4. An aerosol dentifrice according to claim 1 wherein the hydrocarbon propellant comprises one or more C; to Cs hydrocarbon (HC) such as propane, n-butane or butane 22.
5. An aerosol dentifrice according to any one of the above claims wherein the propellant comprises 95:5 or 97:3 w/w ratio of a non-hydrocarbon and liquified hydrocarbon propellant.
6. An aerosol dentifrice formulation being a fluid mixture, comprising water, a liquified gas propellant and a particulate abrasive, characterised in that the particulate abrasive comprises 1-10% by weight of the mixture and has a particle size in the range 5-40 microns and comprises a combination of a more haard and a less hard abrasive.
7. An aerosol dentifrice according to claim 6, wherein the more hard and less hard abrasive is in a proportion of 1:1-5.
8. An aerosol dentifrice according to any one of the atoove claims, wherein the particulate abrasive is a silica.

Nd
9. An aerosol dentifrice according to claim 8, wherein the particle size of the abrasive is less tha=n 30 microns. ) -
10. An aerosol dentifrice according to claim 9, wherein the particle size of the abrasive is less tha n 10 microns.
11. An aerosol dentifrice comprising water, a particulate abrasive ana a liquefied gas propellant, characterised in that the propellant comprises 2-8 wt% of a non- hydroca rbon and 2-6 wt% of a hydrocarbon propellant, the pa rticulate abrasive compris=es 1-10% by weight of the mixture, has a particle size im the range 5-40 microns and comprises a combination of a more hard and a less hard abrasive.
12. An aer«osol dentifrice according to any one of the above claims wherein the water comprises 25-50 wt% of the formulation.
13. An aerosol dentifrice according to claim 12, additionally comprising za humectant.
14. An aer«osol dentifrice according to claim 13, additionally comprisi ng a suspending agent.
15. An aerosol dentifrice according to claim 14, additionally comprising a surfactant.
16. An aerossol dentifrice according to any one of the above claims additieonally comprising xanthan gum and Zeodent 163.
17. An aerosol dentifrice according to any one of the above claims comprising 45-55 wt% humecta nt, 0.1-4 wt%suspending agent, 1-5 wt%surfactant , 3-7 w~t% abrasive, the remainder being water and 3-5 wt% propellant.
18. An aerossol dentifrice according to any one of the above claims comprising a valved container” containing a formulation as described above.