NO157963B - DENTAL CARE CONTAINING FUNCTIONAL, AGGLOMERATED, SPECIFIED PARTICLES. - Google Patents

Description

The invention relates to dental care agents containing functional, agglomerated, speckled particles, where the speckled particles are made of a water-insoluble, powdery, functional material, such as a tooth polishing agent,

and water-insoluble, ethanol-soluble ethylcellulose, preferably together with a water-soluble binder, such as polyvinylpyrrolidone. Such dentifrices can advantageously be packaged in dispensing containers, such as transparent or translucent containers through which the speckled particles can be observed in a transparent or translucent gel dentifrice. In order to achieve the desired visual effects, the speckled particles will usually have a color that forms a contrast in relation to the rest of the dentifrice.

Known toothpastes and gels containing contrast-colored speckled particles are known. Although such speckled particles are in some cases primarily present for aesthetic reasons, they can be based on functional components, such as polishing agents. In the past, various speckled dentifrices have incorporated speckled particles which were initially palpable, but which became insensible during brushing of the teeth. Although such products have been technically accepted, it has also been found desirable to market another type of speckled dentifrice, such as the dentifrice according to the invention, in which the speckled particles, although easily visible and separate, are initially imperceptible and moreover, later while brushing the teeth.

Dental care products containing visible and tangible,

substantially water-insoluble, agglomerated particles of polishing agents are described within the state of the art. Binders have been mentioned as being used in the manufacture of dental care patches, and among the water-soluble binders methylcellulose and polyvinylpyrrolidone (PVP) have been mentioned. However, methylcellulose is water-soluble and therefore does not produce a speckled particle that preserves its structural integrity during long-term treatment. A dentifrice containing an encapsulated sweetener has been described, wherein ethylcellulose was mentioned among a variety of others

materials that were useful for coating the sweetener to form the balls. Water-soluble and water-insoluble binders for speckled particles for dental care have been described together, but ethylcellulose has not been mentioned in such a description. Toothpaste recipes with dispersed, visible agglomerated particles of a tooth polishing agent are known, and advantages of both water-soluble and water-insoluble agglomerating agents or binders have been recognized, but ethyl cellulose has not been proposed for use as a binder in such descriptions. Microencapsulation of sodium fluoride using lower alkyl cellulose, such as ethyl cellulose, and dispersing the capsules in a dentifrice has been proposed, but such a proposal has not been relevant to agglomeration materials for the production of speckled particles for dentifrices.

The invention thus relates to a dental care product of the type specified in the preamble of the patent claim, and the dental care product is characterized by the features specified in the characterizing part of the patent claim.

For the specks in the present toothpaste, ethylcellulose, which is water-insoluble but soluble in ethanol, is used as an agglomerating agent for a functional, water-insoluble, powdery material that has been converted into speckled particles for toothpastes with improved properties. Previously spattered particles produced using water-soluble binders, such as methylcellulose, may break down during treatment after mixing with other dentifrices, such as those previously used in the production of gels or pastes, if the spattered dentifrice was kept for too long in the treatment equipment, which can occur e.g. when mechanical failure of the treatment equipment takes place. Such a loss of structural coherence for the speckled particles could take place because such dental care agents contain water which can dissolve the water-soluble binders in the speckled particles and cause the component particles in the speckled particles to be washed out. The dissolution of the binder can be reduced to a minimum in such cases by rapid processing, but when a stoppage in the filling work causes the processing time to increase, product loss can occur. Stained particles for dentifrices prepared with conventional water-insoluble binders,

as described in the prior art (this prior art does not describe ethyl cellulose), tend to be sensitive when dispersed in dentifrice gels or pastes, and although this may often be desirable, it is not desirable in certain dentifrices, e.g. in dental care products intended for use by people with sensitive gums.

The ethyl cellulose used as a binder for the functional speckled particles helps

to maintain the structural coherence of the specks in the aqueous dentifrice media for a sufficiently long time so that treatment can be carried out after the speckled particles have been incorporated into the dentifrice. Apparently due to the presence of components of the dentifrice which tend to soften the speckled particles on storage,

as flavoring agents, and in some cases surface-active agents, the speckled particles in the dental care agent nevertheless become sufficiently soft during storage so that, although they maintain their structural coherence and independence and their clearly separated appearance until the product is used,

become imperceptible and are easily broken down by brushing the teeth.

In some preferred recipes, such as those recipes that contain a smaller proportion of flavourings

(and dentifrice and any other solvents or lipophiles) or in such dentifrices comprising materials with lower dissolution properties (e.g. ethyl cellulose) the presence of an auxiliary binder which is water-soluble, e.g. PVP, give the desired invulnerability. Nevertheless, the structural coherence of the speckled particles will be preserved due to the presence of the ethyl cellulose.

As soon as they have been made, preferably by means of a method which includes "wetting" a water-insoluble, functional material in powder form (or a mixture of such a functional powder and a water-soluble binder)

with a solution of water-insoluble ethyl cellulose in et

volatile solvent, pressing, conversion to particle form and drying, the speckled particles can be directed in a controllable manner towards a stream of dentifrice and made to adhere to this so that they are evenly distributed, and preferably certain types of apparatus will be used.

The functional, agglomerated, speckled particles consist of two essential components, i.e. a water-insoluble, powdery, functional material and a water-insoluble, ethanol-soluble ethyl cellulose. The first-mentioned component can be characterized as the functional volume-giving agent and the second as the binder. Various functional materials, all of which are preferably water-insoluble or at least slowly soluble, can be used, including coloring materials, such as pigments, germicides, ion exchange agents, polymeric materials (which may contain other active components, sometimes water-soluble materials) or flavoring agents, but it is strongly preferred that the functional base material for the speckled particles is made up of a polishing agent or comprises a main proportion of a polishing agent. Among the polishing agents normally used in dry powder form for the production of the agglomerated, speckled particles, the preferred ones are dicalcium phosphate, tricalcium phosphate, insoluble sodium metaphosphate, aluminum oxide, silicon dioxide, magnesium carbonate, calcium carbonate, calcium pyrophosphate, bentonite or zirconium silicate or suitable mixtures thereof. Both anhydrous and calcined forms of these materials, such as calcined aluminum oxide, or hydrated forms, such as dicalcium phosphate dihydrate, can be used,

but the anhydrous or calcined materials are often preferred. Because the agglomerates will normally and desirably be opaque, there is no need to match refractive indices with the refractive indices of the dentifrice carriers or vehicles.

(also comprising other components), but "transparent" polishing agents with such an adapted refractive index, e.g. 1.44 - 1.47, can be used for the production of transparent or translucent spotted particles and also used for the production of a clear dentifrice-gel main mass containing polishing agent. Such "transparent" polishing agents include colloidal silicon dioxide grades and those sold under the trademark Syloid ® , such as Syloid ® 63, 65, 72 or 74, under the trademark Santocel , such as Santocel 100 or under the designation "Zeo" with the quality designations 49, 113 or 119 , or under the trade name "Zeodent". Moreover, synthetic alkali metal aluminum silicate complexes can be particularly useful because they have refractive indices close to the refractive indices of dentifrice carriers, including water, glycerol, sorbitol or gelling agent, which are those normally used in the manufacture of dentifrices.

The water-insoluble, powdery, functional material used for the production of the speckled particles will normally have an original particle size of 0.5 - 20 ym, preferably 1-10 ym, and preferably 2-8 ym. In some cases, however, larger particle sizes may be used, such as when the agglomeration process tends to reduce the size of a portion of the powder, which may occur during mixing before actual agglomeration begins.

The binder for the speckled particles

is ethyl cellulose. This effective binder is water-insoluble, but is soluble in ethanol, and it gradually becomes soluble in an aqueous glycerol-sorbitol medium which also contains "solvents" for this, such as flavoring agents and surfactants, which are usually present in the dentifrices according to the invention. Such ethyl cellulose will usually have an ethoxy content in the range 45-50%, preferably 48-50% or 48-49.5%. In a preferred ethyl cellulose, such as that marketed under the trademark "Ethocel Standard 10 Premium Ethyl Cellulose", the ethoxy content is

within the range of 48.0-49.5%, the viscosity is 9-11 centipoise,

the moisture content a maximum of 2%, the chloride content, such as NaCl, a maximum of 0.15% and the ash content a maximum of 0.15%.

Ethyl cellulose resins suitable for use as binders for the speckled particles are commercially available in the form of granular powders with a color from white to light leather brown and with a degree of etherification such that 2.25-2.58 ethoxy groups will be present per anhydroglucose unit , which corresponds to an ethoxy content of 45.0-49.5% by weight. Of two such qualities of ethyl cellulose, the materials which are preferred in the execution of the present invention have an ethoxy content within the range of 48.0-49.5 weight percent, and less preferred materials have an ethoxy content within the range of 45.0-46.5 weight percent. Of course, such products are available with different viscosity ranges, usually from 3-110 centipois, the less preferred material tending to have a higher viscosity.

The preferred quality or "standard" quality

of ethyl cellulose tends to be soluble in aromatic hydrocarbons, hydroaromatic hydrocarbons, chlorinated aliphatic hydrocarbons or resinous materials. It is also soluble in aliphatic monohydroxy alcohols, such as ethanol, cyclic monohydroxy alcohols, such as benzyl alcohol, phenylethyl alcohol or pine oil, ether alcohols, such as glycol ethers, ethers, such as diethyl-Cellosolve ® , esters, especially acetates, such as isopropyl acetate or sec-amyl acetate or esters of hydroxy acids, such as methyl salicylate, or ketones, such as cyclohexanone or acetophenone. In general, the less preferred grade or "medium" ethoxy grade of ethyl cellulose is less soluble than the standard grade and thus may be better suited for use when relatively larger amounts of solubilizing materials are present in the dentifrice formulation.

The water-soluble binders that can be used

in the production of the combination binder, which is sometimes preferably used for the production of the speckled particles, includes i.a. acacia gum, gelatin,

starches, both natural and modified, alkali metal carboxymethylcellulose, especially sodium carboxymethylcellulose, polyethylene glycols, sugars, such as glucose or sucrose, methylcellulose, carboxyethylhydroxyethylcelluloses, alginates, especially sodium alginate, polyvinyl alcohol, carrageenan, preferably Irish moss, xanthan gums, tragacanth gum or PVP. It has been shown that PVP is stable in the presence of ethyl cellulose, is not excreted to a large extent from the speckled particles in which it is present as a binder in combination with ethyl cellulose and can be used to regulate the binding properties of the combination binder to cause such a binder will be easily adaptable for use in the same desired total relative amount in a wide variety of different dentifrice recipes in which the relative amount of ethyl cellulose in relation to PVP can be correspondingly adjusted. Also the property of the combination binder in the speckled particles that it is sufficiently hard and firm so that the speckled particles will not be too strongly dissolved during the treatment and will still be sufficiently softenable when stored in the dental care agent in which they have been incorporated so that they become imperceptible when the toothpaste is used is important. They do not soften too strongly so that streaking occurs in the tube or during emptying, but by regulating the relative amount of ethyl cellulose in relation to PVP, i.e. by increasing the content of PVP, regulated streaking can sometimes be achieved if desired.

The PVP used will usually have a molecular weight in the range of 30,000-50,000 and is preferably used with a molecular weight of approx. 40,000. One

such product which is marketed under the trademark Plasdone, such as Plasdone ® K 29-32 or K 26-28, has an average molecular weight which is indicated by K-values, K-30 being equivalent to a molecular weight of approx. 4 0,000. PVP is available as a light colored powder containing less than 5% moisture, 12.6 ± 0.4% nitrogen, less than 2 parts per million (ppm) arsenic and less than 20 ppm heavy metals. It is dissolve-

soluble in cold water and in a number of different organic alcohols, acids, ether alcohols, ketone alcohols, chlorinated hydrocarbons, esters or ketones, but it is insoluble in hydrocarbons and in some ethers, chlorinated hydrocarbons, ketones or esters. It is compatible with various natural and synthetic resins, inorganic salts and a variety of synthetic organic cleaning agents, including those commonly used as dentifrices, e.g. sodium-higher fatty alcohol sulfates or poly-lower-alkylated alcohol sulfates (detergents).

Although it might have been expected that the best speckled particles could be made from the least soluble binder material, it has been found that ethyl cellulose, as described herein, leads to speckled particles with ideal properties and which preserve their individuality and structural coherence, while processed and stored, but which are also essentially imperceptible during use of the dental care agent when brushing the teeth. If desired, the character of the speckled particles can be changed, such as by changing the degree of ethoxy content in the ethyl cellulose and/or by mixing them with other essentially water-insoluble binders of a known type. In a similar way, which reaches the content of lipophilic materials

in the dentifrice (minus the speckled particles) is lower so that the speckled particles are less likely to become insensible during storage, a water-soluble binder, e.g. PVP is used together with the ethyl cellulose to increase the softening of the speckled particles. Such regulation of the specks' properties can also be achieved by using more water-soluble binder or binders or more of such a binder or binders or by changing their molecular weight (e.g. by lowering the molecular weight for PVP). The properties of the speckled particles can also be regulated by regulating the relative amounts of functional material and the binder, as described in more detail below. Agglomerates can thus be made which will be stable during treatment after mixing, such as during venting and filling, but which will nevertheless quickly break down after the toothpaste has been extruded from its container, or if desired such breakdown can

is delayed, so that the agglomerates will feel harder and somewhat firmer to the user when he brushes his teeth. It is normally strongly preferred that the speckled particles are essentially imperceptible during use while at the same time maintaining their identity in the dentifrice.

The binder will normally have a particle size equal to the particle size of the functional, powdery material in the speckled particles, especially if the agglomerates are to be produced, at least partially, by pressing powdery materials. Because the speckled particles will normally be produced by using an alcoholic solution of the ethyl cellulose, the particle size for these can be of relatively little importance. However, when a water-soluble binder is present, their size should preferably be equal to the size of the functional material.

The speckled particles, although they are occasionally white or colorless and possibly even translucent or transparent or have an appearance similar to this, can also be colored, normally due to the fact that they contain a suitable relative amount of an organic dye or pigment or a mixture of organic dyes and/or pigments. Any non-toxic organic dye or pigment of suitable colour, usually a strong colour,

as a color of suitable hue, with a Munsell chroma above 4 and a Munsell value within the range 4-7, may be used, and in some cases faint colors or pastels may be satisfactory or desirable. It is usually best to use an organic dye or pigment that is approved for use in drugs and cosmetics (D&C) or for use in foods, drugs and cosmetics (FD&C). Representative of such organic dyes are D&C Red No. 2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 19, 30, 31, 36 and 37, D&C Blue No. 1, FD&C Blue No. 1 and 2, FD&C Red No. 1, 2 and 3, FD&C Yellow

No. 5, cosmetic green oxide or cosmetic red oxide. Pigments of the above-mentioned organic dyes, known as varnishes, are also suitable for use in coloring the spotted

particles, but normally the organic dyes will be preferred. The aforementioned pigments are often composed of organic dyes carried on a finely powdered, insoluble carrier material, and the pigments are dispersed rather than dissolved in the medium to be coloured. The particle size of the pigments used can lie within the range indicated above for the polishing agents or the size can be equal to the size of the binder. The size can be finer, e.g. within the range 0.01-1 ym. The particle size of the dyes may be similar, but because they are normally used in a dissolved state, in water or a solvent, being preferably soluble in oil and dissolving in the appropriate solvent, the size is not important as long as the powder or particles are sufficiently small that the organic dye will be easily dissolved in the chosen solvent.

The speckled particles can be

made by any method, either by a wet method or a dry method. When ethyl cellulose is used as the sole binder and a wet granulation process is used,

the ethyl cellulose in dry powder form is first preferably mixed with polishing agent and organic dye or possibly pigment and ethanol. Water and/or a lipophilic solvent may be present along with ethanol, and an organic dye or pigment to color the spotted particles may also be present. Alternatively and often preferably, an ethanol solution of ethyl cellulose can be used in mixture with a suitable organic dye or pigment and with the polishing agent. The relative amounts of the components will be such that speckled particles are obtained with the desired composition, and the relative amount of solvent or solvents will normally be 5-50%, preferably 5-25%, of the mixture. Dispersion can be prepared using a Hobart-type mixer,

a pan of the Dravo type or by using another suitable mixing device or a granulator for moistening powder, and the order of addition of the different compo-

nents of dispersion can be regulated in the way that best suits the mixing device used. A preferred way of making the speckled particles is to force the "wetted" mixture of polishing agent and ethyl cellulose

(possibly together with organic dye or pigment)

through a sieve with even apertures which will typically be in the range of 150-2,000 ym (roughly equivalent to U.S. standard sieves No. 10-100), and the "extruded" agglomerates are then dried, usually in air or in an oven . Instead of sieves, other means, such as pressure extruders, can be used to extrude or otherwise pelletize the mixture, after which the particles obtained are dried. The particles are then classified into desired size ranges, normally within the range of No. 10 to No. 80, preferably from No. 40 to No. 80, and more preferably from No. 30 to No. 60 (U.S. sieves). If the moist mass is made in a Dravo pan, the forced screening or other extrusion can of course be omitted. When the particle size is over 2,000 ym (sieve no. 10), they will generally be less satisfactory for introduction into a user's oral cavity, and when the particle sizes are smaller than a diameter of approx. 177 ym (sight no. 80)# they will not be as easily visible and therefore not have an equally appealing appearance.

Instead of using the wet granulation process can

a dry or plug-forming process is used, where the components for the specks can be pressed into a tablet of large size, after which the tablet can be broken into pieces and the particles thereof with a size within the desired size range separated from the other particles.

In such a tablet formation process, it may be desirable to use a water-insoluble lubricant, such as talc, magnesium stearate, calcium stearate or stearic acid, which also helps with the agglomeration. Similarly, such materials and other water-insoluble auxiliaries may be present when wet granulation methods are used. The produced speckled particles are preferably dry, i.e. they do not contain moisture, but moisture in an amount of up to 10%, e.g. 1-5%, can be present without this causing serious adverse effects on the properties of the speckled particles.

The relative amounts in the speckled particles

of a water-insoluble, powdery, functional material, such as tooth polish, and of a binder, such as ethylcellulose or ethylcellulose plus a water-soluble binder, will be such that the binder will constitute the minor component of the speckled particles and the powdery, functional material the main component (although consideration should also be taken into account in the presence of other materials, such as coloring materials and auxiliary additives). The tooth polishing agent or the functional material will make up from 78 to 98% of the speckled particles, preferably 85-97% of these, the binder or combination of binders 2-20% of the speckled particles, preferably 3-15% of these, and the coloring material 0 -5% of the speckled particles, e.g. 0.05-1% of these, all on a dry basis, i.e. free of water and ethanol or other solvents. When the combination of binders is present, the relative amount of ethyl cellulose in relation to water-soluble binder (PVP) is within the range of 1:10-10:1, preferably 1:5-5:1, more preferably 1:2-2:1 , and preferably 1:2-1:1, e.g. 2:3.

The dentifrice in which the speckled particles are distributed can be any suitable such product because, according to the invention, it primarily acts as a medium for the speckled particles by keeping them independent, individual and separate, while at the same time performing its normal dentifrice functions. Opaque dentifrices are useful media for the speckled particles, but it is strongly preferred that the dentifrice is transparent or translucent and is normally of a type characterized as a gel. Dental care products normally contain water, wetting agent, gelling agent (gelling agent), dental care agent (detergent) and a tooth polishing agent, usually also a flavoring agent and/or coloring material. Among the various functional additives, fluorides, stabilizers, anti-tooth decay agents or antibacterial compounds can be mentioned.

The water used is preferably deionized water, although tap water, both soft and hard, can also be used. The gelling agent is normally a water-soluble natural or synthetic gum or gum-like material, and these include carrageenan, tragacanth gum, xanthan gum, alginates, alkali metal carboxymethylcellulose (preferably sodium carboxymethylcellulose), hydroxymethylcarboxyethyl cellulose, polyvinylpyrrolidone, starch or hydrophilic colloidal carboxyvinyl polymers such as those sold under the trade name Carbopol ® 934 or 940. Although various polyols can be used as humectants, those having 3-6 carbon atoms and 3-6 hydroxyl groups per molecule are preferred, and the most preferred are glycerol or sorbitol. The glycerol is available in a normal liquid state and generally with a purity of approx. 99% or more, while the sorbitol, which is normally a solid material, is often used in the form of a 70% aqueous solution (70% sorbitol, 30% water).

The three components mentioned can be regarded as the main components of the dentifrice carrier ("vehicle") in which flavoring agent and cleaning agent can be incorporated. Such a cleaning agent may comprise a soap, but it will normally be a synthetic, organic, surface-active agent which has cleaning properties and which is not a soap. Such a cleaning agent will preferably be of the anionic type, although non-ionic cleaning agents are also useful, ampholytic cleaning agents may be used, and cationic cleaning agents may under certain circumstances be acceptable.

The preferred anionic detergents are particularly useful because they exhibit a combination of excellent cleaning action and foaming properties. Normally, such compounds will comprise relatively balanced hydrophilic and lipophilic parts, with the lipophilic part usually being made up of higher fatty alkyl or acyl with 10-18 carbon atoms, preferably 12-16 carbon atoms, while the hydrophilic part is made up of an alkali metal, f, .ex. sodium or potassium, or of ammonium or lower alkanolammonium. Among such suitable anionic cleaning agents, mention may be made of the water-soluble salts (normally alkali metal and preferably sodium or potassium salts) of higher fatty acid mono-glycerine sulfates, such as the sodium salt of the monosulfated monoglyceride of hydrogenated coconut oil fatty acids,

higher alkyl sulfates such as sodium lauryl sulfate, alkyl aryl sulfonates such as sodium linear dodecyl benzene sulfonate, higher alkyl sulfoacetates, higher fatty acid esters of 1,2-dihydroxypropane sulfonates, the sodium salts of sulfated polyethoxylated alcohols or the substantially saturated higher aliphatic acylamides of lower aminocarboxylic acid compounds, as N-lauroylsarcosine, or sodium, potassium

or the ethanolamine salts of N-lauroyl, N-myristoyl or N-palmitoylsarcosine, all sarcosine compounds being preferably substantially free of soap or a similar higher fatty acid material. Among the non-ionic cleaning agents, ethoxylated sorbitan monostearate with approx. 20 moles of ethylene oxide per mole, condensates of ethylene oxide with propylene oxide and propylene glycol (Pluronic ), polyethoxylated higher fatty alcohols such as Neodol ® (e.g. 23-6.5 or 45-11), or the condensation product of α-olefin oxides containing 10-20 carbon atoms , polyhydroxy alcohols containing 2-10 carbon atoms and 2-6 hydroxyl groups or ethylene oxide or heterogeneous mixtures of ethylene oxide and propylene oxide. Quaternary imidazoyl derivatives, such as Miranol or other Miranol grades, represent useful amphoteric detergents, and the quaternary ammonium halides, such as dimethyldicetylammonium bromide, represent cationic detergents.

The various polishing agents that are dispersed

in the dentifrice carrier (or in the carrier plus cleaning agent and any other auxiliary additives) are those described above for conversion to suppository form. Also useful within such a group of materials are synthetic finely divided silicon dioxide grades, such as those sold under

the trademarks Cab-O-Sil M-5, Syloid 244, Syloid 266, Aerosil<®> D-200, Zeosyl® 200 or Zeothix" 265, which are normally used only in a small percentage of the polishing agent, normally in an amount of not above 1-9 percent by weight of the total dentifrice, and which are useful because they thicken or gel the carrier and improve the clarity of the dentifrice.

The dentifrices according to the invention will normally contain suitable flavoring agents and/or sweeteners. Examples of flavoring agents include the flavoring oils, such as the oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, cinnamon, lemon or orange, and the sweeteners include sucrose, lactose, maltose or saccharin. Sodium fluoride, divalent stannous fluoride, potassium fluoride, potassium tin (II) fluoride, sodium hexafluorostannate, tin (II) chlorofluoride and/or sodium monofluorophosphate will preferably also be present in fluoride-containing dental care products.

The flavoring agents comprise various well-known essential oils, mainly terpenes, esters, alcohols, aldehydes, ketones or other aromatic substances, a large number of which emit aromatic odors and fragrances. Because taste impressions are based on a simultaneous physiological and psychological reaction to the presence of a material in the mouth and are dependent on the senses of taste, smell and feeling, as the smell is often of

importance, it is not surprising that aromatic materials are important constituents of flavoring agents. For the present dentifrice, this fact and the chemical nature of such materials are utilized which, as previously indicated in the discussion of the solubility of ethyl cellulose, enables the ethyl cellulose binder in the present speckled particles to be slowly dissolved as a result of the solubilizing substances in the flavoring agent , whereby the speckled particles become soft,

but does not lose its structural integrity. For example, the terpenes, which are hydrocarbons and which form an important group of materials for perfumes or flavoring agents, are good solvents for the ethyl cellulose used according to

invention, in the same manner as a number of other flavoring agents, such as those discussed above (such as flavoring oils), and others well known in the perfumery and flavoring industry. Because the flavor essences in the dentifrice are used to soften the ethyl cellulose specks and thereby make them insensitive, which is a goal of the invention, it is unnecessary to add another component to the dentifrice or to the speckled particles for this purpose. Because the relatively small amount of flavoring agent is normally present in a dentifrice, as the relative amount of the lipophilic part of the flavoring agent is often smaller, a desired slow softening of the speckled particles can also be obtained,

usually due to a relatively low mass transfer rate of the "dissolving" material, the transfer rate being particularly reduced due to the gelatinous nature of the dentifrice. Even if part of the flavoring agent at the interface between the speckled particle had started to soften the ethyl cellulose therein while the dentifrice was being mixed, the flavoring solution of ethyl cellulose would thus soon be saturated, and this would have inhibited a further rapid dissolution of the ethyl cellulose. Nevertheless, the speckled particles will become insensible, but remain separate,

during the normal time that a dental care product is stored before sale and use, and this time will often be at least approx. 2

weeks and sometimes longer (for certain dentifrice mixtures it is desirable that they should be stored to improve the taste and consistency of the product).

In the above description, reference has been made to the ethylcellulose binder, but it will be understood that occasionally a water-soluble binder, such as PVP, could also be present, and this reference was also intended to apply to such speckled particles and speckled dentifrices. In such products, the ethyl cellulose holds the speckled particle together until it has been "dissolved" by the lipophilic ingredients in the dentifrice, and the PVP used makes it possible to use less cellulose and facilitates the desired softening of the speckled particles in dentifrices containing smaller relative amounts of solubilizing flavoring agent and other lipophilic constituents.

Although it is considered that the flavoring agents, especially the lipophilic flavoring agents, which exert a significant dissolving effect on the ethyl cellulose, are the most important slowly dissolving components in the present dentifrices, the component consisting of the surface-active agent comprising a lipophilic part, can also exert a significant solubilizing effect and can due to its wetting effect

promote mass transfer in a dentifrice tube and thereby increase the dissolution rate of the ethyl cellulose. It is also possible that combinations of other components in the dental care agent, including some of the sweeteners and carrier components, will further facilitate the solubilization of the ethyl cellulose to the desired degree while not promoting a premature softening of the speckled particles.

Coloring materials, such as those mentioned above in connection with the speckled particles, can be used, and normally in a smaller relative amount, to provide a base which forms a contrast with the speckled particles. Various other additive materials may be present in the dentifrice, including preservatives, silicones, chlorophyll compounds or ammoniacal materials. When a dentifrice gel is made which is to be transparent or translucent, normally the polishing agent chosen will be a polishing agent with a refractive index which closely matches the refractive index of the rest of the dentifrice medium. In such clear dentifrice gels, the amount of insoluble materials present which would cause the gel to tarnish will of course normally be kept to a minimum. When the pH of the dentifrice is regulated, the pH being preferably within the range 3-10, more preferably within the range 3.5-5 when divalent tin ions are present, and within the range 4.5-7 in the absence of such ions, organic acids, such as citric, malonic or fumaric acids are used.

In the dental care agent according to the invention, a tooth polishing agent is evenly distributed throughout the carrier consisting of water, humectant and gel agent which already contains a dental care cleaning agent and the desired amount of flavoring agent. The speckled particles, which also preferably contain a polishing agent (and often of a different type than the polishing agent present in the main mass of the dentifrice), are then again distributed throughout the dentifrice and usually amount to 0.1-10%, preferably 0, 5-5%, more preferably 1-3% and preferably 1.5-2.5%, of the dentifrice. The toothpaste base will usually comprise 5-30%, preferably 10-25%, and more preferably 10-20%, water, 20-70%, more preferably 45-65%, and preferably 50-60% of a humectant which preferably consists of a polyol humectant, and 0.1-5%, preferably 0.1-1%, and more preferably 0.2-0.5%, gelling agent. The humectant is preferably made up of a mixture of glycerol and sorbitol in which the glycerol content is 5-40%, preferably 20-30%, of the toothpaste base and the sorbitol content is 5-50%, preferably 25-35%. The preferred gelling agent is sodium carboxymethylcellulose, and a preferred amount used of this is 0.3-0.4%. The content of dental cleaning agent is normally 0.5-5%, preferably 0.5-3%, and a preferred cleaning agent is sodium lauryl sulfate. The polishing agent in the dentifrice base, not including the polishing agent present in the speckled particles, is normally 10-40%, preferably 15-30%, and most preferably 20-25%, comprising silicon dioxide grades of the type Syloid 244

which is also used for thickening. Various other materials, including flavoring agents (usually 0.5-2%), coloring materials, preservatives, sweeteners or tooth-hardening agents (fluorides), will normally make up no more than 10% of the dentifrice, preferably 2-7% of this.

When the various components are used within the above-mentioned quantity ranges in relation to the speckled particles and the medium in which they are distributed, an appealing product is obtained which is stable during storage and in which the speckled particles are evenly and attractively distributed.

It is relatively easy to produce the speckled dentifrice after the speckled particles have first been produced, but an important trade-off is that minimal mechanical agitation should be used to prevent or delay any breakdown, softening and dissolution of the speckled particles in the dentifrice. It is believed that lipophilic materials and solvents present, such as those present in flavor oils, will slowly dissolve ethyl cellulose, but not to an undesired extent if vigorous agitation is not performed during treatment. If the dentifrice is at too high a temperature during such mixing, possibly due to production limitations during treatment, it is even more important to keep stirring to a minimum. However, when the ethyl cellulose binder or a combination binder is used in the manufacture of the speckled particles, the manufacturing limitations need be less stringent, but care should still be taken. Suitable equipment for distributing the spattered particles throughout the dentifrice may include conventional Banbury type mixers or dough mixers operated at low speed, but other mixers operated under mild conditions may also be used provided mixing is controlled to prevent significant degradation, dissolution or cleavage of the speckled particles. When such mixers are used, the blade speed in the mixer will normally be 1-5 revolutions per minute (rpm) and the mixture will last 1-5 minutes. After mixing is complete, the dentifrice is deaerated and filled into containers, such as transparent, springy or squeezable tubes. If a vacuum is used during the mixing operations, deaeration can be bypassed.

Although the above-mentioned manufacturing apparatus and

process is standard in the manufacture of speckled dentifrices, it is far preferable to use methods which have recently been invented to facilitate the mixing of the speckled particles into the dentifrice gel without too much agitation. Such processes and devices are described in more detail below, and invent-

nelsen will be easily understood from this description considered in connection with. the attached drawings, of which Fig. 1 shows in perspective a tube for a toothpaste gel according to the invention, from which the cap has been removed, and a toothbrush,

Fig. 2 schematically shows an apparatus

for producing a speckled dentifrice from a dentifrice and previously prepared speckled particles,

Fig. 3 shows in perspective and on an enlarged scale part of the "woodpecker apparatus" that is used

and shows application of the spotted particles to a gel stream or a gel band,

Fig. 4 schematically shows another device

for the production of a stained dentifrice,

and

Fig. 5 shows in perspective and on an enlarged scale part of the "woodpecker apparatus" according to fig. 4 and the application of the spots to gel streams or bands.

Fig. 1 shows a container 11 with a clear wall made of a transparent polymer material (PVC), comprising a main part 13, a shoulder 15, a threaded neck 17 and cap 19, the cap having been removed from the tube. Although it is preferred to make the packaged dentifrice using a deformable tube of a clear or translucent synthetic organic polymer material, such as polyvinyl chloride, polyethylene, polyvinylidine chloride or a similar material in which the appealing appearance of the speckled dentifrice can be observed, collapsible opaque tubes, such as tubes of aluminum or another metal, are used. As shown, a dentifrice 21 is discharged from the tube 11 through the neck 17 and onto the bristles of a toothbrush 12. In the dentifrice, speckled particles 23 are clear

shown in the continuous dentifrice medium 25. It should be noted that these speckled particles are initially insensible although they are readily visible. When the teeth are brushed, they are broken down into smaller units of essentially the same size as the polishing agent in the toothpaste.

The speckled polishing agent naturally works together with the polishing agent in the toothpaste gel and helps to clean and polish the teeth.

In fig. 2 shows a container 111 for the production of a gel and which will often preferably consist of a mixing device of the Hobart or Dopp type and in which the various components for the dental care agent, including carrier material, gelling agent, polishing agent, flavoring agent, coloring material, cleaning agent, preservative and any other additives, are mixed together, occasionally under vacuum, to form a mixture to which speckled particles, preferably functional speckled particles, such as those based on a dentifrice polishing agent, are to be added to make a speckled dentifrice. A motor and/or drive device 113 with variable speed drives a positive displacement pump 115 with adjustable speed to deliver the gel to an outlet 117 which is preferably constituted by a somewhat limited flat opening through which the gel is extruded or discharged in the form of a flat band or in the form of another suitable stream 119 on which the speckled particles 121 in the form of separate pieces or particles are deposited. A pump 115 can be set so that it regulates the feed rate of the gel,

and also by regulating the feed rate for the speckled particles, the desired relative amount of these can be continuously supplied to the gel stream. The pump 115 is preferably a pump that exposes the gel to little or no shearing action in order to thereby preserve the gel's consistency (viscosity),

and screw pumps with elastomer walls are preferred, such as those of the Moyno type. A gel feed outlet device or

- extruder 117 is preferably enveloped by a container 123

and will normally be in such a position therein that bands of gel containing speckled particles on its surface which have been produced in such a container will fall vertically to the bottom thereof near the center of the container, from where they can be removed via a central expiration 125.

The speckled particles to be added to the dentifrice gel in the prescribed proportional quantity,

is located in a silo 127 for a feeding device 129

which is able to control the flow rate, preferably of a coil spring type, and comprises a speed control device 131, the feeding device exhausting the spattered particles at a desired controlled speed via an outlet 133 on a funnel-shaped control device 135 which shapes the exhausted stream of spattered particles as desired so that when they leave the control device 135, they will form a falling stream or a curtain which is adapted to the band of gel flowing from the outlet 117 and which is preferably such that the spattered particles fall substantially vertically down so that they are deposited on and adheres to the inner part of the gel band and so that no particles fail to come into contact with the gel. The curtain of speckled particles preferably covers a substantial part, e.g. 40-95%, preferably 60-90%, of the width of the gel tape, and the curtain should not be so wide that any significant part of the spotted particles will fail to hit the tape. However, it would be desirable for the curtain to have a width that is only slightly smaller than the width of the tape if this is possible, e.g. 80-90%. Lines 137, 139 and 141 are connected with. vacuum sources or 143 and 145, but even if the use of a vacuum is desirable to prevent air bubbles from entering the dentifrice, infiltration of such bubbles can be avoided without the use of a vacuum if the process is carefully controlled. After the spattered dentifrice has been allowed to fall through an outlet 125, a pump 147 which is preferably a screw pump, such as a Moyno type pump, driven by a variable speed motor 149, gently pumps the product into a static mixer 151, preferably of the Kenics type, in which it is carefully mixed without breaking down or dissolving the speckled particles in the dentifrice, and this is evenly mixed. It is then transferred via a line 153 to a receiving device 155 which can be a feed tank for a tube filling machine (not shown).

According to fig. 3 comprises a gel feeding device

157 a delivery tube 159 and a nozzle part 117, the nozzle comprising a flat, rectangular shaped opening 161.

The gel feeding device and the opening in the discharge "nozzle" - part of this can be adjustable. The feeding direction can therefore be changed as desired, and the discharge angle can be varied, but the feeding direction should have a horizontal component and usually forms an angle of 0-45°, f .eg 10-30°

relative to horizontal. The size of the rectangular opening can also be changed so that it becomes more narrow, but care should be taken so that the gel band remains continuous so that it will not become so thin that the gel strength will be insufficient. As a rule, the tape will have a thickness of from 1 mm to 1 cm, e.g. 2-6 mm. The stream or band of gel is given such a direction that the stream or curtain of speckled particles can correctly fall on it, preferably when the speckled particles fall substantially vertically and the gel moves in a direction with a horizontal component, so that the gel will pass under the falling speckled particles that come into contact with the gel and adhere to it. A gel band 163 is shown falling downwards and to the right, while speckled particles 165 fall onto this from a discharge spout 167 for a directional device 135 (Fig. 2).

In fig. 4, a gel preparation container 211 is shown

which may be similar to that shown in fig. 2 and act in a similar way. By means of valves 213 and 215 in a line 217 - together with a positive displacement pump 219 at an adjustable speed, circulation of the gel through the mixing apparatus can be achieved if desired. Lines 220 and 221 and valves 222 and 223 enable the dentifrice gel (or paste) to be discharged for cleaning or preparation of a dentifrice containing no speckled particles. When a line 225 and a valve 227 are open and the valves 215, 222 and 223 are closed and the valve 213 is open and the gel pump 219 is in use and the mixing device 211 contains the dental care gel, the gel can be delivered at a controlled rate to a gel feeding device 220 and via a line 231 to a similar but oppositely arranged gel feeding device 23 3, both of these devices comprising relatively narrow and flat openings or nozzles, as better shown in fig. 5. They also preferably comprise further support devices for the gel

as it leaves the nozzles, to help maintain ribbon shape and to control ribbon flow. The pump 219 can be set so that it controls the feed rate for the gel, so that when the feed rate for the speckled particles is controlled, the desired proportional amount of speckled particles can be continuously supplied to the gel flow. The pump 219 will preferably be similar to the previously described pump 115. The gel feeding devices or extruders 229

and 233 and the line 231 is preferably enclosed by a container 235 and will, as a rule, be centrally arranged in this, so that superimposed layers of gel with speckled particles inside them and produced in such a container will fall vertically or substantially vertically to the bottom of this near the center of the container, from where they can be removed via an outlet connected to a line 237. The outlet (reference number not given) is located at the bottom of the container, and it is preferred that the gel feeding device 233 is terminated near the outlet to reduce wave formation on the layer tape containing the speckled particles to avoid air entrapment being caused (when vacuum is not applied). It is also preferred that the shape of the outlet is adapted to the shape of the band (usually flat and rectangular) and that it is oriented in the same direction as this in order to reduce any obstacle to the removal of the dentifrice from the container to a minimum and to reduce the residence time, air entrapment the formation and dissolution of the binder for the speckled particles to a minimum.

The speckled particles to be added to the dentifrice gel in the prescribed proportional quantity are contained in a silo 230 for a feeding device 232 which can effect a controlled flow rate, preferably of the spiral spring type, comprising a speed control and motor combination device 234, the feeding device emptying the spattered particles at the desired controlled speed via an outlet in a pipe 23(5) on a distribution device 238 which spreads the spattered particles out so that as they leave the distribution device, they will form a falling stream or a thin curtain having a size and orientation that is adapted to the size and orientation of the ribbons obtained by means of nozzles 229 and 233. Instead of a coil spring feeder, other feeders of the screw, belt or vibration type may also be used. Line 228 forms a connection to a vacuum source which, in the same way as the vacuum line 259 can be activated or to-ko stain or not.

Valves 239 and 241 are arranged for selective

make it possible to drop the product down through a line 243 or a connection with a pump 24 5 which is preferably of the Moyno type. The screw pump 245 driven by a motor 247 carefully pumps the product through a line 249 to a static mixer 251 which is preferably of the Kenics type and in which the product is gently mixed without breaking down or dissolving the spattered particles therein, and is evenly mixed . It then flows through a line 253 to a receiver 2 55 which may be a feed tank for a tube filling machine (not shown).

Although the device can be used

and the use of this can take place without a vacuum being used, it will often be desirable to avoid the penetration of air into the dental care materials, and the whole operation or part of it can be carried out under vacuum. The feeding device for the spattered particles and the "applying device" for the spattered particles are preferably under vacuum, and vacuum lines or nozzles 259 and 228 are therefore indicated in the drawing.

According to fig. 5 comprises the gel feeding devices

229 and 233 the nozzle part 275 and 277 with narrow surface openings respectively. 263 and 26 5, as the nozzle parts as shown are in connection with supporting control devices or

267 and 269 which can be adjustable and which enable a correct routing of the bands or paths of gel so that the curtain or screen of speckled particles can correctly fall on them. The gel band on the control device 26 7 is denoted by 271 and is. shown without speckled particles having been deposited on this. A similar band 272 on the guide device 269 exhausts the gel band during the discharge from the first guide device and

near the outlet from the container. The curtain of speckled particles preferably falls vertically or substantially vertically onto the gel band 271 after the band has left the guide device 267, but while still moving in a direction with a horizontal component, e.g. with an angle of 60° to the horizontal. However, if care is taken, some speckled particles can be caused to fall onto the gel 271 while this is still in contact with the supporting device. As the gel band 271 with adhering speckled particles falls vertically or substantially vertically, it comes into contact with the band 272, and the two bands form layers on top of each other with the speckled particles between them. To avoid undulations that may cause entrapment of air, the guide device 269 may extend straight or in the form of a convex curve preferably close to (usually within 5-25 cm) the outlet opening from the container, and the gel band passes through the oriented and similarly shaped outlets without wave formation, as the discharge rate is kept equal to the sum of the addition rates. The feeding rates (and thicknesses) for the gel tapes can be approximately the same or they can be varied, as such relative rates are usually within the range 1:4-4:1. The controlled and quantity-adjusted feed of separated speckled particles comes from the delivery pipe 236 on a distribution device 238 which is shown in the form of an expanding chute comprising side walls 279 and 281, a bottom 283 and separator bars 285 arranged to correspond to "Pascal's triangle ". The feeding devices for the spattered particles and the gel and the openings in the discharge "nozzle" portions of such gel feeding devices may be adjustable, as described in connection with fig. 3. The first or upper stream or band of gel is directed so that the stream or curtain of speckled particles, usually with a thickness of 0.5-5 mm, can correctly fall on it, preferably when the speckled particles fall essentially vertically and the gel is moved in a direction with a horizontal component, so that the gel will flow under the falling speckled particles that contact and adhere to the gel. The gel band 271 is shown falling downwards and to the right, while the speckled particles 273 fall onto the band from the distribution device 238 for the directional device 235 (Fig. 4), and the band 272 falls downwards and to the left below the band 271.

The apparatus described in connection with fig. 2-5 and

the corresponding processes make it possible to produce speckled toothpastes efficiently and quickly without the need to use any ordinary cutting and mixing apparatus. Moreover, the speckled particles do not clump together nor are they broken into pieces, and because the process is fast, the product is quickly processed and can be filled into tubes before any significant softening or dissolution of the dentifrice-binder takes place. The preferred clear gel dentifrice as a rule with individually visible, separated, functional speckled particles attractively distributed in this will thus be obtained without bleaching of the dentifrice which is due to breakdown of speckled particles and distribution of the finely divided, functional material, such as polishing agent, through the dentifrice.

Other benefits are

that the speckled particles are made immobile in relation to the gel band and leads to less dissolution of any binding agent used in any solvent materials that may be present in the gel. The feeding of the gel in the form of an arc that becomes vertical over a container outlet after the speckled particles have been deposited reduces the residence time in the apparatus before removal and thereby reduces such dissolution of the binder for speckled particles and prevents breakdown of the speckled particles. Moreover, the "sandwich" effect shown in fig. 4 and 5, to an even better distribution of the speckled particles in the dental care material, and this is particularly advantageous for dental care products to which the speckled particles do not adhere strongly.

All parts listed here are based on weight unless otherwise stated.

EXAMPLE 1

5 parts ethylcellulose (10 centipoise) with the physical characteristics previously described and which is in the form of a powder, is dissolved in 5 parts ethanol (95%) and mixed in a Hobart type mixer with 9 5 parts calcined aluminum oxide (Microgrit WCA 9F) with a particle size within the range 0.5-10 ym and an average particle size within the range 3-5 ym. Mixing is continued for approx. 4 minutes until the mixture has become smooth, after which the mixture is forced through a 2.00 mm sieve

(US standard sieves), and the "extruded" material is oven dried for 1 hour at 65°C. The dried agglomerates are then sieved through a 595 µm sieve, and the fraction retained on a 250 µm sieve, i.e. the dried speckled particles containing calcined aluminum oxide and the ethyl cellulose, is collected. The speckled particles produced have an angular shape, as the ratio between the maximum length and the maximum width is usually within the range 1-2 and most of the particles have such a ratio within 1.1-1.5. The angular shape of the particles can constitute a variable for the production of the dental care products that have such an appealing appearance, at least for some consumers.

A transparent (or translucent) dentifrice base (comprising all components except the speckled particles) is prepared according to the following recipe.

5 parts of the described speckled particles with particle sizes from 250 pm to 500 pm are pre-

carefully mixed in a slow mixing device (approx. 2 rpm) with 95 parts of the described dentifrice base, after which the mixture is deaerated and automatically filled into capped squeezable tubes which are then closed. During mixing, venting and tube filling, the speckled particles, which are essentially evenly distributed throughout the toothpaste, remain separate, independent and undissolved in the toothpaste base, so that when the tube is opened after filling and preferably after storage for approx. 1 month and the dentifrice is squeezed out through the tube's discharge opening, it appears that the speckled particles have retained their original structural coherence and form a contrast with the bluish gel. When the product is judged immediately after filling and without having been stored, the speckled particles are palpable, but when stored before use for a period of from 2 weeks to 1 year or longer, they have become sufficiently soft, e.g. in that the ethyl cellulose has been dissolved by the flavor oils, sometimes with the help of the dental care cleaning agent or another surface-active agent that can

be present, or other components, so that they appear separate and not "smeared", but they are nevertheless satisfactorily insensible. When the teeth are brushed with the dental care product, the speckled particles are easily reduced in size, do not irritate the gums and can be easily removed from the oral cavity after brushing is finished.

Although the presence of the anionic detergent in the dentifrice base may be of some assistance, it is believed that the controlling component in such a base is the 1.2% flavoring agent present. An amount of such a flavoring agent or a mixture of such flavoring agents of from 0.5-2%, preferably 0.8-1.5%, of which at least half is normally active as a solvent for ethyl cellulose,

is desirable in order to achieve the best dispersion of speckled particles, and the flavoring agent will usually comprise more than 50%, often more than 80%, of solubilizing hydrocarbons, esters, alcohols and aldehydes.

The manufacturing method that has been described for the dentifrice, where the speckled particles are dispersed in the main mass of the gel, is a method where the mixing itself should be monitored to ensure that the speckles do not break into pieces, and at any sign of this taking place, the mixing should be stopped and the tubes are immediately filled, provided that the appearance of the toothpaste has not been significantly adversely affected, usually by making it unacceptably tarnished. Instead of using the described mixing method, it will often be preferable to use other treatment methods that have been described previously, where a regulated uniform "fan" of speckled particles is deposited under the influence of gravity onto a continuously falling, extruded gel band to which the speckled particles adhere , to achieve an even distribution of the speckled particles in the toothpaste. When the speckled toothpaste according to the invention is packaged in a squeezable aluminum tube, the speckled particles in the toothpaste are not visible until the toothpaste is squeezed out of the tube, but at this point they remain separate in the extruded toothpaste and give it an appealing, distinctive appearance. If, however, resilient transparent tubes, such as tubes of polyvinyl chloride or of another suitable polymer, are used instead of the normal aluminum tubes, the speckled particles can be seen through the tubes and through the transparent dentifrice gel base, and their movement can be observed when the toothpaste is squeezed out. This provides a further aesthetic advantage that makes brushing the teeth more interesting, especially for children.

The functional speckled particles also act as a reminder to the person using the dental care product,

that a polishing agent or another functional component is present in the dental care product, whereby the person is reminded of the importance of brushing the teeth so that such a component can work effectively.

The above recipe is a recipe for a dentifrice gel in which the normal amount of 41.04% of a sorbitol solution has been reduced to 36.04% to enable the specified 5% of speckled particles to be introduced. The effect of this change in the recipe is that the percentage of the other dentifrice components is the same as in a product without speckled particles, apart from the sorbitol solution which forms the main component.

It is considered that with other variations in the content of the speckled particles in such dentifrices, such a method of changing the recipe can still be followed. However, it is possible to start with the original gel formation, e.g. containing 41.04% of the sorbitol solution, and to reduce each of the components in relation to this so that the desired percentage amount of speckled particles can be introduced.

According to a variation of the above described

experiment, 1% of an ultramarine blue pigment can be used instead of the 1% Microgrit, so that the speckled particles get a distinct blue colour. Instead of the described amount of ultramarine blue, 0.5-2.0% of this pigment or mixtures of pigments and polishing agent or polishing agents in relative amounts of from 1:10 to 10:1 can be used. Alternatively, 0.1-1% of any suitable water-insoluble (or oil-soluble) organic dye may be used. In such cases, the dye solution may be omitted from the dentifrice base recipe or it may be present, provided an adequate

contrast between the spotted particles and the base can be achieved.

The various components according to the recipe can of course be replaced with others, such as those previously described, and useful products will also be obtained. For example, the various mentioned pigments and organic dyes can be used, sodium lauryl sulfate can be replaced with sodium-ethoxylated-higher fatty alcohol sulfate or sodium-hydrogenated-coconut oil fatty acids-monoglycerin-monosulfate/and the polishing agents can be replaced with dicalcium phosphate dihydrate and/or dicalcium phosphate (anhydrous) or mixtures thereof. The relative amounts of the various components can be modified by ±10%, +20% and ±30% as long as they are kept within the previously indicated ranges, and the result is satisfactory products with similar properties, even if the product at the relative amounts according to this example are preferred.

Example 2

75 parts anhydrous dicalcium phosphate and 15 parts dicalcium phosphate dihydrate, both of which have average particle sizes of approx. 4 ym, is mixed with 10 parts of ethyl cellulose and 10 parts of ethyl alcohol in a mixing apparatus of the Hobart type. Alternatively and preferably, ethanol and ethyl cellulose can be pre-mixed and can then be mixed with a pre-made mixture of the dicalcium phosphates. The resulting mass is forced through a sieve with uniform apertures of 2,000 ym and is then dried in an oven for 1 hour at 65°C. The dried agglomerates are then sieved through a 420 µm uniform aperture sieve, and the agglomerates that do not pass through a 177 µm uniform aperture sieve are collected.

Then the obtained agglomerated, functional particles are mixed with a dentifrice base according to the recipe given in example 1, but with the exception that the polishing agent in the base is replaced with sodium aluminum silicate,

such as the sodium aluminum silicate which is marketed under the trade name Zeolite 4A, and that the percentage amount of speckled particles in the final product is 2% (whereas the sorbitol solution present is increased by 3%).

In variations of this recipe, hydrated aluminum oxide with an average particle size of less than approx. 10 ym, calcium carbonate with particles, essentially all of which have a diameter below approx. 7.4 µm, or insoluble sodium metaphosphate with an average particle size of approx. 5 ym (since all such sizes are final particle sizes), is used as a polishing agent in the speckled particles.

The dentifrices according to this example are speckled, transparent or translucent products and have an aesthetically pleasing appearance. The visible particles of the agglomerated polishing agents (for which other functional, insoluble materials can be used in whole or in part) are essentially evenly distributed in the dentifrice base in the form of visible, separate units and are essentially imperceptible when used after storage for 3 months.

Example 3

Instead of dissolving the ethyl cellulose in ethanol or another suitable solvent, agglomerates are prepared by mixing the polishing agent and the ethyl cellulose, sometimes with a reduced proportion of ethanol present, to form a powder mixture. This is pressed on a rotating tablet press to form plugs with a thickness of approx. 6 mm and a diameter of 25 mm. The plugs are then granulated in an oscillating granulator to form smaller particles, preferably such that they will pass through a 595 pm sieve and be retained on a 250 pm sieve or

177 pm term. This method for producing the speckled particles can also be used in connection with any recipe for the speckled particles given in the preceding examples. Although the binding effect of the ethyl cellulose will not be as strong, according to this example the products are also satisfactory for incorporation into dental care products in order for these to have aesthetically beneficial and functional effects. If the binding effect of the ethyl cellulose in the above recipe is not sufficient, the amount present can be increased, sometimes up to 100 or 200%,

but such an increase involves additional costs, and the "wet" method, in which solutions of ethyl cellulose in ethanol or other suitable solvents are used, is therefore often preferred.

Example 4

95 parts of calcined aluminum oxide (Microgrit WCA 9F) with a particle size within the range of 0.5-10 ym and an average particle size within the range of 3-5 ym are mixed with 3 parts of powdered polyvinylpyrrolidone which is marketed under the trade name Plasdone K-29-32. 2 parts of ethyl cellulose powder of the type mentioned in example 1 are dissolved in 5 parts of ethanol (95%), and the PVP aluminum oxide mixture is mixed with the solution in a mixing apparatus of the Hobart type. Mixing is continued for approx. 4 minutes until the mixture has become smooth, after which the mixture is forced through a No. 10 sieve and the "extruded" material is dried in an oven, as described in Example 1. The dried agglomerates are then sieved and collected, as described in Example 1.

The speckled particles produced are angular in shape, and the ratio between the maximum length and the maximum width is generally similar to the ratio indicated in Example 1. A transparent (or translucent) dentifrice base (comprising all components except speckled particles) is prepared similar to that produced according to Example 1, except that 39.04 parts of sorbitol solution are present instead of 36.04 parts. 2 parts of the described speckled particles with a particle size of from less than 595 µm to more than 250 µm are carefully mixed in a slow mixer (about 2 rpm) with 98 parts of the described dentifrice base, after which the mixture is deaerated and automatically filled into hooded squeezable tubes which are then closed. The treatment used is similar to that described in example 1.

When the product is judged immediately after filling and without

have been stored, the speckled particles are palpable, but when stored before use for a period of from 2 weeks to 1 year or longer, they have been sufficiently softened to be imperceptible, e.g.

in that they have been dissolved by the PVP used by the moisture present or in that the ethyl cellulose has been dissolved by the flavoring oil, both dissolution processes apparently occasionally taking place with the aid of the dental cleaning agent or of some other surface-active agent that may be present , and occasionally also supported by other components.

When the amount of flavoring in the dental care gel base is reduced to 0.6%, i.e. half of the amount indicated in the above recipe, the binder system of PVP-ethyl cellulose for the speckled particles still works effectively, and these remain satisfactorily imperceptible during storage. It is also effective when the flavoring concentration is varied to 0.3%, 0.9% and 1.5%. The larger proportion of flavoring agent (and/or other lipophilic solvents) may, however, cause an earlier dissolution than preferred, and in this case the proportion of PVP and ethyl cellulose will preferably be varied, e.g. to 2 parts PVP and 3 parts ethylcellulose. If, in a similar way, the sensitivity of the speckled particles should increase beyond what might be desired, they can be made softer by increasing the PVP proportion, e.g.

to twice the proportion of the ethyl cellulose. The concentrations of speckled particles and their size can be varied within the previously indicated ranges. Moreover, other of the previously indicated materials can be used instead of the aluminum oxide polishing agent, including other types of water-insoluble, functional materials. The variations in recipe and methods described in example 1 also apply to the present example, and the products obtained are also usable as speckled particles and speckled dentifrices.

Example 5

75 parts anhydrous dicalcium phosphate and 15 parts

dicalcium phosphate dihydrate both with an average final particle size of approx. 4 ym, is mixed with 5 parts ethyl cellulose, 5 parts PVP and 10 parts ethyl alcohol in a Hobart mixer. Alternatively and preferably, ethanol and ethyl cellulose can be pre-mixed with each other and then mixed with one another

pre-made mixture of the dicalcium phosphates with PVP. The resulting mass is forced through a 2,000 µm even aperture sieve and is then dried in an oven for 1 hour at 60°C. The dried agglomerates are then sieved through a 420 µm uniform aperture sieve, and the agglomerates that do not pass through a 177 µm uniform aperture sieve are collected. Then the obtained agglomerated functional particles are mixed with a dentifrice base of the composition given in Example 4, except that the polishing agent in the base is replaced by sodium aluminum silicate, such as that marketed under the trade name Zeolite 4A.

The dentifrices according to this example are speckled, transparent or translucent products and have an aesthetically pleasing appearance. When variations are made in the recipe and production method, as in example 2, good products with the desired properties are also obtained.

Example 6

The functional polishing agent component according to example 5 is replaced by a mixture of 10 parts anhydrous dicalcium phosphate and 90 parts calcium carbonate, the same overall proportion of polishing agent being used. Otherwise, the same method is followed. The products obtained similarly have satisfactory functional effects and an aesthetically pleasing appearance. Similar results are obtained when different mixtures of the described polishing agents are instead used for the present mixture in the speckled particles and when the proportions of these are varied.

Example 7

Instead of dissolving the ethyl cellulose and PVP in ethanol or another suitable solvent, the agglomerates are made,

as the agglomerates according to example 6, by mixing the polishing agent, PVP and ethyl cellulose, occasionally with a reduced proportion of ethanol present, forming a powder mixture. This mixture is pressed on a rotary tablet press to form plugs with a thickness of approx. 6 mm

and a diameter of 25 mm. The plugs are then granulated in an oscillating granulator to form smaller particles, preferably particles of such a size that they will pass through a 420 µm sieve and be retained on a 250 or 177 µm sieve. Although the binding effects of PVP

and the ethyl cellulose does not need to be so strong, the products according to this example are also satisfactory for incorporation into dental care products to contribute with their aesthetic benefits and functional effects. If the binding effects of the PVP and ethyl cellulose used in the above recipes are not sufficient, the present proportions of these can be increased, sometimes up to 100 or 200%, but such increases entail additional expenses, and therefore the "wet" method where solutions of PVP and ethyl cellulose in ethanol or other suitable solvents are used, often preferred.

Example 8

In the above examples, the polyvinylpyrrolidone, i.e. the water-soluble binder portion of the combination binder, has been partially replaced (50%) or completely replaced with the following water-soluble binders: acacia gum, gelatin, corn starch, sodium carboxymethylcellulose, sodium alginate, polyvinyl alcohol, carrageenan, xanthan gum and tragacanth gum. When the manufactured speckled particles are incorporated into dentifrice gels similar to those previously described in these examples, they will sufficiently preserve their individuality and structural coherence during treatment, but they will become insensible when stored in the dentifrice while retaining their original form, in the same way as the speckled particles prepared with PVP-ethylcellulose combination binders. However, it is considered that the combination binder of PVP-ethyl cellulose is generally superior due to its combination of desirable characteristics, comprehensive stability during treatment, compatibility with dentifrice components and conversion from palpability to non-palpability without loss of structural coherence of the speckled particles and without significant change in appearance.

Example 5

Speckled particles with different compositions are compared with speckled particles based on ethylcellulose and PVP. The speckled particles for the dental care agent according to the invention are generally made in the manner described in example 4, i.e. by the wet method, and the recipe for the speckled particles comprises 95% calcined aluminum oxide, 2% ethylcellulose and 3% PVP, these materials being the same as those used in Example 4. The speckled particles for the comparative experiments are also prepared by the wet method, except for one type, which will be indicated, which was prepared by the dry method, or the "plug" method according to Example 7.

The speckled particles were examined by 100 mg

of each type were weighed out and separately placed on glass plates, four drops of Vcinn were added to each portion of spiked particles, each glass plate was covered with another glass plate, and the time elapsed before physical change occurred and the type of physical change in the granules was noted. When 2% sodium carboxymethylcellulose is used as a binder, the speckled particles lose their structural coherence within fifteen seconds, and this is also the case for speckled particles bound with 2% hydroxypropylmethylcellulose, but it then takes 2 minutes. Spotted particles made with a binder comprising 2% methylcellulose and 3% PVP become soft, swell and lose their structural coherence after approx. 2 minutes, and when 5% PVP is used as the only binder, speckled particles produced with this will become soft after 8 minutes. When the binder is 1% methylcellulose (400 centipoise), the speckled particles will lose their structural coherence after just over 5 minutes, and when the binder is changed to 10% polyethylene glycol 6,000

together with 1% magnesium stearate, as the speckled particles are produced by the "plug" method, the speckled particles will lose their structural coherence after 19 minutes. The speckled "control" particles of the invention containing 2% ethyl cellulose and 3% PVP still remain intact after over 6 hours when subjected to the same test.

Example 10

By a frsftncjang way where

the device according to fig. 2 and 3 are used, a speckled, clear toothpaste gel is produced with the recipe and method described in example 1. The different components for the gel or paste are mixed with each other in the mixing device 110 and pumped, preferably using a Moyno type pump , to the extruder which is terminated with a flat "split" nozzle, as shown, with a relatively narrow, rectangular opening. Such a nozzle will preferably have a slope downwards from the horizontal plane with an angle of 10-45°, e.g. 30°.

The feed rate of the speckled particle feed mechanism, which is a spiral spring feed device of the Acrisan type, is regulated so that it corresponds to the gel feed rate. When, for example, a content of speckled particles in the dental care agent of 3% is desirable, the speckled particles will be fed in a quantity of 93 g/min if the feed rate for the gel is 3 kg/min. Usual electronic or mechanical means can be used to maintain the desired feed ratio or to regulate this if variations in the relative amounts are desirable for the different products.

In the drawing, the feeding mechanism for the speckled particles is only schematically shown in fig. 2, and only its end is shown in fig. 3, but different types of feeding devices, including screws, belts, weight belts, electronically controlled gravimetric feeding devices or others can be used, and the discharge pattern can be varied. The discharge will be such that few, if any, speckled particles will fall past the gel, and the gel flow will hold onto the speckled particles that collide with it. Moreover, the speckled particles will fall apart, and the gel will move sufficiently quickly under them with a speed of usually 10-100 cm/s, e.g. 20-50 cm/s, until the individual speckled particles will collide with the gel and adhere to it, as very few speckled particles will hit other already held speckled particles and bounce off them. Moreover, all, or almost all, such speckled particles that bounce off will later adhere to the dentifrice mixture.

The descending spotted gel to which the spotted particles adhere is not retained for a long time in the walled container in which or above which the spotting apparatus is arranged, because the gel falls through the center of the container and most of the gel continues almost directly to the outlet. This short residence time in the "sputter container" is very desirable and helps to maintain the structural coherence of the sputtered particles in the dentifrice. Although the residence time in the container can vary, typical residence times are from 20 seconds to 2 minutes, and the shorter the better. Such rapid passage, the absence of mobile speckled particles and the central discharge of gel from the container also help to avoid aggregation of speckled particles into unwanted clumps. The additional volume in the walled container is for receiving gel that can be fed into the container during periods when the filling equipment can be temporarily stopped and before the feeding of the container can be stopped. The walled container can thus often contain only a small proportion of spotted gel, e.g. 10-25% of the container's volume. Alternatively, another material may act as a "wall" surrounding the spotted gel in the container.

After the gel has left the "spike container", it is carefully pumped using a Moyno type pump and passed through a static mixer to ensure complete mixing. The preferred static mixer, specifically a Kenics type mixer, is similar to that described in Chemical Engineering, March 19, 1973, in an article entitled "Handling Viscous Materials - Motion-less Mixer for Viscous Polymers". Although it is desirable to use a mixing device before the gel is emptied and transferred to a filling machine or a suitable container which is arranged in front of such a machine, the method and the device, without such a mixing device, can often sufficiently lead to the p>attached <p>articles are distributed throughout the gel, so that in some cases the mixer is not used.

The working conditions are not considered to be critical,

but as a rule the vacuum used will lie within the range 300-700 mm Hg, e.g. 400-600 mm Hg. The temperatures can be approximately room temperature or higher, e.g. within the range 10-40°C. The extrusion pressure for the gel varies with the viscosity of the gel, but 0.03-0.7 kg/cm 2 is considered to be a reasonable range.

The various parts of the equipment

should be made of non-corrosive and safe materials because they are used in the treatment of an oral care product. It has been found that stainless steel components are strongly preferred, and the mixers, extruders, pumps and valves and any other parts that come into contact with liquid or gel-like materials will preferably be made of stainless steel as normally used in the food industry - the processing industry.

When a clear dentifrice with 2% speckled particles and containing silicon dioxide, sorbitol, glycerol, CMC, sodium lauryl sulfate, flavoring agent and water in the gel, and

where aluminum oxide and ethyl cellulose are present in the speckled particles, such as the toothpaste described in example 1, is made using the apparatus described here, the product obtained will be precisely the desired product with the speckled particles evenly distributed throughout the clear gel and without any flaking or broken down speckled particles being observed. Similar results can be obtained when the dentifrices according to examples 2-9 are prepared using the apparatus and method as described.

When carrying out the method described

it will be understood that although it is preferred that the dentifrice gel or paste is in the form of a flat band, variations of such shape can be used, such as curved bands and even cylindrical or tubular streams. Although it is preferred that the stream or curtain of speckled particles be a suitably thin, straight curtain of such material,

e.g. with a thickness of from 0.1 mm to 1 cm, e.g. 0.5-5 mm, which fall under the influence of gravity, the speckled particles can also be forced against the dentifrice. In some cases, e.g. a vertical stream of dentifrice is exposed to spattered particles which are directed horizontally towards it, the spattered particles which do not adhere to the dentifrice being collected for recycling. The dentifrice stream can be given a rotating motion so that over its fully exposed surface it will "pick up" speckled particles that are directed towards it in one direction. Entrained speckled particles can collide with a gel stream and be deposited on it so that they become immobile and separate . Although such variations of the present invention can be used, the method described and shown here is however considered superior.

The proportion of speckled particles which. supplied to the belt or web of dentifrice gel which is kept in motion, will constitute a smaller proportion compared to the complete speckled dentifrice and compared to the supplied amount of gel. The feed rate for the speckled particles will usually be regulated so that the amount of speckled particles directed at the gel will be insufficient to cover it and preferably insufficient to cover more than half of the area of the gel portion that is exposed to the curtain of speckled particles particles when the curtain comes into contact with the gel. Although, as previously mentioned, various ways of bringing the spotted particles to adhere to the gel band have been discussed, it is strongly preferred that the spotted particles are allowed to fall vertically in the form of a curtain against a gel band moving in a direction of a horizontal component. This direction can be horizontal or have a significant horizontal component in relation to the falling gel after the speckled particles have been taken up, but normally an inclination in relation to the horizontal of e.g. 10-60° be preferred for the gel, while the speckled particles fall vertically after being discharged from a delivery device. The viscosity of the gel is not of critical importance as long as the spotted particles adhere sufficiently strongly to the gel, and the size of the particles lies within the range from 0.177 to 2.000 mm, preferably within the range from 0.177 to 0.595 mm, and more preferably within the range from 0.250 to 0.595 µm. The speckled particles preferably have sharp edges, and when they fall towards the gel flow, they become partially embedded in it and immediately become immobile,

but similarly good results can also be obtained when more rounded speckled particles are used. The speckled particles used are visible in a clear gel, which makes the product aesthetically pleasing. The term "speckled particles"

refers to visible separate particles in the form of agglomerates of finely divided polishing agent and binder, although they may include other "active ingredients, such as therapeutic agents, coloring materials, flavoring agents or fluorides.

The toothpaste material that they

speckled particles are deposited on, may constitute the entire dentifrice, apart from the speckled particles, but this is not necessary. It is possible to mix some of the dentifrice components with the other dentifrice materials after the speckled particles have been added. It can e.g. it may be desirable to mix in the flavoring agent, which may contain some volatile components, before the Kenics mixing device, but after a possible application of vacuum to the product during the deposition of the speckled particles. Such a method offers the advantage that the flavoring agent is protected

and that loss of more volatile components from this is avoided during the application of the vacuum during the supply of the speckled particles, and any flavoring components that will be able to dissolve the binder in the speckled particles will be in contact with them for a shorter processing time. The mixing device of the Kenics type or another static mixing device which provides a relatively low cutting force will nevertheless mix the flavoring agent sufficiently evenly throughout the toothpaste.

In a similar way, other components, usually smaller amounts of auxiliary additive components, can be added to the dentifrice after the speckled particles have been incorporated therein.

The mentioned walled container into which the spattered dentifrice falls can be kept under vacuum or it can be open to the atmosphere. The spitting device may have an underlying reservoir rather than this being enclosed in a container. However, it is preferred that the equipment is covered and under vacuum if the absorption of air would otherwise pose a problem. It acts as a container for the sputtering device in addition to holding the product obtained.

The present method and the present apparatus

can be used for the production of dentifrices according to a wide range of different recipes with different proportions of speckled particles. It is a simple matter to vary the concentration of the spiked particles as this can be done simply by changing the speed of the spiked particle feeder and by regulating the gel feed rate accordingly.

Among the various benefits can

mention is made of increased operating yield, reduced use of mixing devices with moving parts and stabilization of the toothpaste gel or paste. It is known that various dentifrices are diluted if they are subjected to too strong mechanical processing, and by the mixing process described here for the addition of speckled particles

to the toothpaste, such processing is avoided and makes it possible to maintain the desired viscosity for the toothpaste gel.

Example 11

A method for producing a stained dentifrice is carried out as described in example 10, but the apparatus used is the apparatus shown in fig. 4 and 5.

Two gel bands are therefore produced, of which each band makes up half of the total amount of toothpaste (without the speckled particles). The flat slit nozzles have a slope downwards with an angle of approx. 30° in relation to the horizontal. The gel speed is 20-50 cm/s and the gel is preferably sufficiently sticky and the conditions regulated so that most of the speckled particles that collide with the first gel flow will adhere to it, the rest (or essentially all the rest) being clamped in place between the first gel flow and the second gel flow.

The device for feeding the speckled particles is, as shown in fig. 5, a chute with staples arranged on the chute in accordance with "Pascal<1>'s triangle". It has a downward slope with an angle of approx. 30° in relation to the horizontal, and has a width at the delivery end of approx. 90% of the width of the gel flows. Although it is preferred that the pins are arranged in accordance with "Pascal's triangle", of course differently designed feeding devices can also be used.

The dental care agent obtained offers all the advantages that the dental care agent according to example 10 offers. Moreover, the method and apparatus used according to the present example are particularly suitable for keeping the speckled particles on the dentifrice gel in an orderly arrangement and uniform distribution therein if the gel is not strongly sticky. Thereby, it is avoided that the spattered particles "bounce off", thereby reducing the loss of spattered particles and thereby the need to recycle or scrap non-adherent spattered particles. Even when using gels that are not sticky (and/or speckled particles that are not adherent), the final product can also be regulated so that it has a uniform and desired content of speckled particles (due to the loss of speckled particles being kept to a minimum .

Claims (1)

Dentifrice comprising water, humectant, gelling agent, detergent and flavoring agent, all of which constitute components of a gel carrier for the dentifrice, and a tooth polish which is uniformly distributed throughout the carrier, characterized in that it comprises visible, functional, speckled particles distributed throughout the dental care product and which are made up of agglomerates with sizes in the range from 0.177 to 2.00 mm and for 75-98% by weight are made up of a tooth polishing agent selected from the group consisting of dicalcium phosphate, tricalcium phosphate, insoluble sodium metaphosphate, aluminum oxide, silicon dioxide, magnesium carbonate, calcium carbonate, calcium pyrophosphate, bentonite and zirconium silicate and mixtures thereof, and for 2-20% by weight of water-insoluble, ethanol-soluble ethyl cellulose.