WO2020193244A1

WO2020193244A1 - Solid oral care composition

Info

Publication number: WO2020193244A1
Application number: PCT/EP2020/057045
Authority: WO
Inventors: Rahul BACHPALLE; Vaishali Gode; Om SHELKE; Akshata WALAWALKAR
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2019-03-28
Filing date: 2020-03-16
Publication date: 2020-10-01
Also published as: CN113645937B; EP3946218A1; BR112021018670A2; CN113645937A

Abstract

The present invention relates to a solid oral care composition for use in the cleaning of teeth which is formulated to have optimum friability where there is minimal breakage of the composition during manufacture, transport and storage while being easy to chew by the consumer. Disclosed is a solid oral care composition comprising: (i) a first grade of calcium carbonate with an average particle size in the range of 1 to 20 microns, preferably in the range of 2 to 10 microns; (ii) a second grade of calcium carbonate with an average particle size in the range of 200 to 800 microns, preferably 350 to 650 microns and (iii) organic polyol comprising maltitol. The first grade of calcium carbonate is included in 5 to 30% by weight of the composition and wherein the second grade of calcium carbonate is included in 10 to 40% by weight of the composition and the weight ratio of the first grade of calcium carbonate to the second grade of calcium carbonate is in the range of 1:1 to 1:2.

Description

SOLID ORAL CARE COMPOSITION

Field of the Invention

The present invention relates to a solid oral care composition, more particularly to a tablet composition that is chewed and then optionally brushed to provide cleaning of the oral cavity. The composition is formulated such that the friability is low during manufacture, transportation and storage of the composition, yet can be easily chewed by a person to break down in the oral cavity to provide the desired cleaning.

Background of the Invention

Oral care compositions like toothpaste, toothpowder, oral care tablet, mouthwashes etc are manufactured to provided one or more benefits to the oral care cavity, the primary benefit being cleansing of the cavity, especially the teeth, gums and the mucous membranes of the oral cavity. Oral care compositions are sometimes called dentifrices which generally contain an orally acceptable abrasive. Additionally, other ingredients like humectant, antimicrobial agent, flavour, preservative, fluoride and water are included in order to provide other benefits. Most oral care compositions in the market contain high amount of water which adds to the cost due to transportation, adequate packaging and need for high level of preservatives. Efforts have been made in the past to market environmentally acceptable products like toothpowder and tablet.

EP3131640 (Unilever, 2015) relates to a solid oral care composition comprising calcium carbonate and carboxymethyl cellulose. EP3131639 (Unilever, 2015) relates to a solid oral care composition comprising calcium carbonate and polyethylene oxide. The polymer causes the tablets to disintegrate quickly.

WO2015158639 A1 (Unilever) discloses oral care tablets for cleaning teeth, as an alternative to toothpastes, The composition comprises calcium carbonate and carrageenan where the weight ratio of carrageenan to calcium carbonate is from 1 :20 to 1 :100. Carrageenan speeds up disintegration of the tablets.

W02005110378 A1 (Huber) also discloses tablets for clearing the teeth. The tablets contain a calcium carbonate a super disintegrant; and a sugar alcohol. When immersed in water the tablet has a friability of less than about 2% and disintegrates in less than about 60 seconds.

While the tablet composition disclosed in the above patent publications provide the desired cleaning and other benefits expected from such an oral care composition, the present inventors found that the products made with the technology disclosed in the above prior art have a higher than acceptable friability during manufacture, transport and storage. The present inventors have experimented extensively to arrive at the present invention which involves using two different grades of calcium carbonate together with polyol including maltitol which provides the desired balance between the strength needed to minimize breakage or friability during manufacture and transport while being not too hard to chew. The above properties have to be met while ensuring that undesirable sensory characteristics such as gritty or chalky mouth feel is minimized.

It is an object of the present invention to provide for a solid oral care composition with improved friability.

Summary of the Invention

The present invention provides for a solid oral care composition comprising:

(i) a first grade of calcium carbonate with an average particle size in the range of 1 to 20 microns;

(ii) a second grade of calcium carbonate with an average particle size in the range of 200 to 800 microns and

(iii) organic polyol comprising maltitol, wherein the first grade of calcium carbonate is included in 5 to 30% by weight of the composition and wherein the second grade of calcium carbonate is included in 10 to 40% by weight of the composition and the weight ratio of the first grade of calcium carbonate to the second grade of calcium carbonate is in the range of 1 :1 to 1 :2.

The invention also relates to a method of cleaning teeth comprising the step of chewing the composition of the invention. Detailed Description of the Invention

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word“comprising” is intended to mean“including” but not necessarily“consisting of” or“composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

The present invention relates to solid oral care composition, preferably in the form of a tablet. More preferably, it is in the form a compressed tablet.

Composition of the invention comprise calcium carbonate as the desirable abrasive for mechanically abrading the surface of the teeth and removing debris and plaque deposited thereon. Calcium carbonate for use in the present invention are of two grades:

By microns as per this invention is meant micrometer. The particle size as reported herein is measured using the dry dispersion method (Malvern Mastersizer). The first grade of calcium carbonate has an average particle size in the range of 1 to 20 microns, preferably in the range of 2 to 10 microns. The most preferred particle size of this first grade has a D50 around 5 microns with D10 of less than 1 micron and a D90 of 20 microns.

This second grade of calcium carbonate has an average particle size in the range of 200 to 800 microns, preferably 350 to 650 microns. The most preferred particle size of this second grade has a D50 around 500 microns with D10 of 200 microns and a D90 of 800 microns.

The particle size mentioned above are those of primary particles of calcium carbonate. By“primary particles” is meant individual particles, defined as the smallest discrete particles that can be seen by electron microscopy analysis (such as, for example, individual crystals). The primary particles may associate under certain conditions to form larger secondary structures such as aggregates or agglomerates. For the purposes of the present invention, a suitable source of particulate calcium carbonate includes crystalline calcium carbonates.

The term“crystalline” (in the context of particulate calcium carbonate) generally means a particulate calcium carbonate in which at least 50% by weight, preferably at least 75% by weight, more preferably at least 90% by weight, most preferably more than 95% by weight and ideally more than 99% by weight of the calcium carbonate particles are in the form of crystals. The term "crystal" means an essentially fully dense solid composed of atoms arranged in an orderly repetitive array bounded by plane surfaces which are the external expression of internal structure. Crystals may be identified and characterised by standard techniques known to those skilled in the art such as X-ray diffraction.

Crystalline calcium carbonates suitable for use in the invention are available naturally (through the extraction and processing of natural ores) or synthetically (through chemical precipitation). There are three main crystalline polymorphs: calcite, aragonite, and less commonly found, vaterite. The vaterite form of calcium carbonate is metastable and irreversibly transforms into calcite and aragonite. There are many different morphologies (crystal habits) for each of these crystalline forms. The calcite crystalline polymorph is the most commonly used crystal form of calcium carbonate. Over 300 crystalline forms of calcite have been reported in the literature.

Particle (e.g. crystal) size may be determined by standard techniques known to those skilled in the art such as sedimentation. For the present invention the particle size is determined using a Malvern Mastersizer. In the context of the present application the average particle size measurements relate to D50. Suitable sources of crystalline calcium carbonate of the size and shape defined above include natural ground calcium carbonate abrasives, generally obtainable from mining and mechanical grinding of sedimentary rocks such as limestone or chalk, or metamorphic rocks such as marble. Natural calcium carbonate is usually of the calcitic polymorph, with a crystal morphology which may typically be characterised as rhombohedral. Preferred natural ground calcium carbonate abrasives of the type defined above are selected from ground limestone, chalk or marble, optionally refined or partially refined to remove impurities. Commercially available examples of the first grade of calcium carbonate include those materials sold by the company OMYA™ AG under the names OMYACARE™ 5AV. These are fine ground high purity white marble abrasives having an average particle size about 5 microns. Commercially available examples of the second grade of calcium carbonate include those materials sold by the company OMYA™ AG under the names OMYASCRUB™ 20KA. These are fine ground high purity white marble abrasives having an average particle size about 500 microns.

Other types of particulate calcium carbonate may also be suitable, depending on the particular balance of cleaning and abrasion required from a consumer perspective.

The first grade of calcium carbonate in the composition of the invention is included in 5 to 30%, more preferably 10 to 25% by weight of the composition. The second grade of calcium carbonate is included in 10 to 40%, more preferably 15 to 30% by weight of the composition. The total amount of calcium carbonate of all types is preferably from preferably from 15% to 70%, more preferably from 30% to 70% most preferably form 30 to 60 wt% by weight by total weight of the composition. The weight ratio of the first grade of calcium carbonate to the second grade of calcium carbonate is in the range of 1 :1 to 1 :2, more preferably in the range of 1 : 1.2 to 1 :1.8.

The composition of the invention includes an organic polyol comprising maltitol. By an organic polyol as per this invention is meant a polyhydric alcohol having two or more hydroxyl groups in the molecule. Maltitol is one organic polyol which is included in the composition of the invention. The composition preferably includes at least one more polyol. The additional polyol may be selected from one or more of sucrose, dextrose, maltose, fructose, glycerol, sorbitol, xylitol, mannitol, lactitol, isomalt, erythritol, polyethylene oxide, polypropylene glycol, propylene glycol, and hydrogenated partially hydrolyzed polysaccharides such as hydrogenated starch hydrolysates. Preferred organic polyols for use in this context are non-cariogenic polyhydric alcohols selected from one or more of glycerol, sorbitol, or xylitol. Of these, the most preferred additional polyol is xylitol. Highly preferred compositions include a mixture of maltitol and xylitol. These materials serve as binders to aid in compression of the composition during processing. They also act as humectants. Humectants help to keep the composition from hardening or crystallizing upon exposure to air. They also help to give the composition a moist feel to the mouth, and may in some cases impart a desirable sweetness. The present inventors have through their extensive experimentation understood that the optimum friability of the solid oral care composition of the invention is derived from the selective combination of the inorganic particles of the two grades of calcium carbonate bonded together with the polyol maltitol and preferably with inclusion of another polyol which may be xylitol. Thus, when xylitol and maltitol are included in the composition of the invention the weight ratio of xylitol to maltitol is preferably in the range of from 1 :0.5 to 1 :2, more preferably 1 :0.8 to 1 :1.4.

Maltitol is preferably included in 10 to 50%, more preferably 15 to 30% by weight of the composition. An additional polyol e.g. xylitol, if included, is preferably included in 10 to 30%, more preferably 15 to 25% by weight of the composition.

The total amount of organic polyol is preferably included in 20 to 60%, preferably 25 to 50% by weight of the composition.

Details on xylitol and maltitol which are the preferred organic polyols for use in the present invention are given below.

Xylitol occurs as a white, granular solid comprising crystalline, equidimensional particles having a mean diameter of about 0.4 to 0.6 mm. It is odorless, with a sweet taste that imparts a cooling sensation. Xylitol is also commercially available in powdered form, and several granular, directly compressible forms. Xylitol is used as a noncariogenic sweetening agent in a variety of pharmaceutical dosage forms, including tablets, syrups, and coatings. It is also widely used as an alternative to sucrose in foods and as a base for medicated confectionery. Xylitol is finding increasing application in chewing gum, mouth rinses, and toothpastes as an agent that decreases dental plaque and tooth decay (dental caries). Xylitol is highly effective in enhancing the flavour of tablets and syrups and masking the unpleasant or bitter flavours associated with some pharmaceutical actives and excipients. Granulates of xylitol are used as diluents in tablet formulations, where they can provide chewable tablets with a desirable sweet taste and cooling sensation, without the‘chalky’ texture experienced with some other tablet diluents.

Maltitol occurs as a white, odorless, sweet, anhydrous crystalline powder. It is a disaccharide consisting of one glucose unit linked with one sorbitol unit via an alpha-(1- 4) bond. The crystal structure is orthorhombic. Maltitol is widely used in the

pharmaceutical industry in the formulation of oral dosage forms. It is a noncariogenic bulk sweetener, approximately as sweet as sucrose, well adapted as a diluent for different oral dosage forms, wet granulation, and sugar free hard coating.

Suitable foaming agents may preferably be used in forming the composition. Preferred foaming agents include surfactants. Surfactants help to increase the rate of dissolution of the solid oral care composition when in contact with saliva, and assist in foaming of the composition during usage.

Suitable surfactants include anionic surfactants, such as the sodium, magnesium, ammonium or ethanolamine salts of Cs to Cie alkyl sulphates (for example sodium lauryl sulphate), Cs to Cis alkyl sulphosuccinates (for example dioctyl sodium sulphosuccinate), Csto Cis alkyl sulphoacetates (such as sodium lauryl

sulphoacetate), Cs to Cis alkyl sarcosinates (such as sodium lauryl sarcosinate), Cs to Cis alkyl phosphates (which can optionally comprise up to 10 ethylene oxide and/or propylene oxide units) and sulphated monoglycerides. Other suitable surfactants include nonionic surfactants, such as optionally polyethoxylated fatty acid sorbitan esters, ethoxylated fatty acids, esters of polyethylene oxide, ethoxylates of fatty acid monoglycerides and diglycerides, and ethylene oxide/propylene oxide block polymers. Other suitable surfactants include amphoteric surfactants, such as betaines or sulphobetaines.

Preferred surfactants for use in the invention include those anhydrous surfactants selected from sodium lauryl sulfate, sodium lauryl sulfoacetate, cocam idopropyl betaine, sodium alpha olefin sulfonate, dioctyl sodium sulfosuccinate, sodium dodecyl benzene sulfonate and mixtures thereof. Mixtures of any of the above described materials may also be used. The total amount of surfactant incorporated into the composition of the invention generally ranges from about 0.1 to about 5%, more preferably 0.5 to 3% by total weight surfactant based on the total weight of the composition.

The composition of the invention may additionally comprise modified cellulose or modified starch, preferably modified cellulose. Most preferred modified cellulose for use in the composition of the invention is carboxymethyl cellulose preferably sodium carboxymethyl cellulose (SCMC). When included, SCMC is included in 0.1 to 3%, more preferably in 0.5 to 2% by weight of the composition. When included, SCMC is included in an amount such that the weight ratio of SCMC to calcium carbonate is from 1 :20 to 1 : 100, more preferably 1 :30 to 1 :50.

The composition may also include various additional ingredients to improve aspects such as ease of processing, product performance and/or consumer acceptability.

The composition of the invention is typically non-aqueous. By“non-aqueous” it is generally meant that water is not deliberately added to the composition in any significant quantity. However, the term“non-aqueous” does not mean that small amounts of water cannot be present, for example as a consequence of its association with hygroscopic raw materials. Accordingly, for the purposes of this invention, the term“non-aqueous” generally means that water is present in an amount no greater than about 5%, more preferably no greater than about 3% by weight based on the total weight of the composition.

The solid oral care composition of the invention will generally take the form of a discrete, single unit dose such as a pellet, pastille or tablet. Such a single unit dose will typically range in size from 200 mg to 5000 mg, preferably from 250 mg to 2000 mg, more preferably from 500 to 1500 mg.

Compositions according to the invention are particularly suitable as a vehicle for oral care actives which may be physically or chemically incompatible with water, or which may function less efficiently in an aqueous environment.

Specific examples of oral care actives which may be particularly suitable for inclusion in the compositions of the invention are as follows. Water-soluble or sparingly water-soluble sources of zinc ions may be included in the composition to act as antimicrobial agents. Suitable zinc salts which may be included are zinc chloride, zinc acetate, zinc gluconate, zinc sulphate, zinc fluoride, zinc citrate, zinc lactate, zinc oxide, zinc monoglycerolate, zinc tartrate, zinc pyrophosphate and zinc maleate. Most preferred zinc salts are zinc citrate and zinc sulphate. The zinc salts may be included in amounts of 0.1 to 5%, preferably 1 to 4% by weight of the composition.

Oral care enzyme systems such as hydrogen peroxide producing enzyme systems (e.g. the oxidoreductase enzyme glucose oxidase), amyloglucosidase, dextranase and/or mutanase, (optionally in the presence of zinc ion providing compounds and/or 8- hydroxyquinoline derivatives), lactoperoxidase, lactoferrin, lysozyme and mixtures thereof may also be included.

Fluorides sources are also preferably included in the solid oral care composition of the invention. Fluoride sources such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, zinc ammonium fluoride, tin ammonium fluoride, calcium fluoride, cobalt ammonium fluoride and mixtures thereof may be included. Most preferred fluoride sources are sodium fluoride or sodium monofluorophosphate most preferably sodium fluoride. When included, fluoride source is included in 0.01 to 2%, preferably 0.1 to 1 % by weight of the composition.

Compositions of the present invention may also contain further optional ingredients customary in the art such as anticalculus agents, buffers, flavouring agents,

sweetening agents, colouring agents, opacifying agents, preservatives, antisensitivity agents, antimicrobial agents and the like.

The solid oral care composition of the invention is used to clean the surfaces of the oral cavity. The composition is an oral care composition that is not intentionally swallowed for purposes of systemic administration of therapeutic agents, but is applied to the oral cavity, used to treat the oral cavity and then expectorated. Typically the composition is used in conjunction with a cleaning implement such as a toothbrush, usually by applying it to the bristles of the toothbrush and then brushing the accessible surfaces of the oral cavity. Tablets of the invention are preferably manufactured using a compaction process which subjects the composition to a pressure in the range of to 1 to 8 tons. Preferably the tablets are not coated. According to another aspect of the present invention there is provided a non- therapeutic method of cleaning the teeth comprising the step of chewing the

composition of the invention. The composition is preferably chewed from about 10 seconds to about 5 minutes, more preferably from about 3 seconds to about 2 minutes. The teeth are then preferably brushed with a toothbrush. The composition is thereafter not swallowed but spat out of the oral cavity. The oral cavity may thereafter be rinsed with water to substantially remove all of the chewed composition from the mouth.

The composition as claimed in the present invention is also herein claimed for use in cleaning teeth.

The invention is further illustrated with reference to the following, non-limiting examples.

Examples

The following three tablets compositions were prepares as shown in Table -1.

Table 1

SLS powder is Sodium lauryl sulphate.

Calcium carbonate (Grade 1) is calcium carbonate with an average particle size of 5 microns. Calcium carbonate (Grade 1) is calcium carbonate with an average particle size of 500 microns.

The above samples were tested for friability using the following apparatus and procedure:

Friability is measured for the compressed uncoated tablet. Measurement of tablet friability supplements the other test such as breaking force and physical strength of the tablet formulation. Friability test tells how much mechanical stress tablets are able to withstand during their manufacturing, distribution and handling by the customer.

The Friability Apparatus used to measure the friability was Model Dual Drum Friability Tester from Electrolab, India. The Friability apparatus works on the principle of attrition and impact to provide the stress to the tablet. Tablets were rolled over each other to give attrition and tablet is dropped from a height of 6 inches to give the impact to the tablet. The test is conducted for 100 revolutions which indicates 100 impacts on tablet along with attrition.

The percentage weight loss was then calculated using the following formula:

Initial weight— Final Weight

% Weight Loss = Z 100

Initial Weight

It is accepted that loss of mass for over a single determination or an average of three or five determinations should be than 1.0% for the tablet to be considered acceptable for commercial use.

The data for the three samples prepared is summarised in Table -2 below: Table 2

The data in Table 2 above indicates that composition as per the invention (Example - 1) provides for acceptable friability (of less than 1%) while compositions outside the invention (Example A and B) do not.

Claims

1. A solid oral care composition comprising:

(i) a first grade of calcium carbonate with an average particle size in the range of 1 to 20 microns, preferably in the range of 2 to 10 microns;

(ii) a second grade of calcium carbonate with an average particle size in the range of 200 to 800 microns, preferably 350 to 650 microns and

(iii) organic polyol comprising maltitol, wherein the first grade of calcium

carbonate is included in 5 to 30% by weight of the composition and wherein the second grade of calcium carbonate is included in 10 to 40% by weight of the composition and the weight ratio of the first grade of calcium carbonate to the second grade of calcium carbonate is in the range of 1 : 1 to 1 :2.

2. A composition as claimed in claim 1 comprising an additional organic polyol selected from glycerol, sorbitol, xylitol and mixtures thereof.

3. A composition as claimed in claim 2 wherein the additional organic polyol is xylitol.

4. A composition as claimed in claim 3 wherein the weight ratio of xylitol to maltitol is from 1 :0.5 to 1 :2.

5. A composition as claimed in any one of the preceding claims wherein the organic polyol is included in 20 to 60% by weight of the composition.

6. A composition as claimed in any one of the preceding claims further comprising a foaming agent selected from the group consisting of anhydrous surfactants selected from sodium lauryl sulfate, sodium lauryl sulfoacetate, cocam idopropyl betaine, sodium alpha olefin sulfonate, dioctyl sodium sulfosuccinate, sodium dodecyl benzene sulfonate and mixtures thereof.

7. A composition as claimed in claim 6 wherein the foaming agent is sodium lauryl sulfate.

8. A composition as claimed in claim 6 or 7 wherein the foaming agent is included in 0.1 to 5% by weight of the composition.

9. A composition as claimed in any one of the preceding claims in the form of a compressed tablet.

10. A non-therapeutic method of cleaning teeth comprising the step of chewing the composition as claimed in any one of the previous claims.

11. A composition as claimed in any one of the preceding claims 1 to 9 for use in cleaning teeth.