EP4387586A1

EP4387586A1 - Oral care composition comprising iota carrageenan and kappa carrageenan

Info

Publication number: EP4387586A1
Application number: EP22758223.6A
Authority: EP
Inventors: Long GAO; Huajin Jin; Weining LIU; Jinfang Wang
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Priority date: 2021-08-19
Filing date: 2022-08-01
Publication date: 2024-06-26
Also published as: CN118234477A; WO2023020817A1; CL2024000375A1

Abstract

An oral care composition is disclosed comprising iota carrageenan, kappa carrageenan, an anionic surfactant, and a pigment having a hue angle, h, in the CIELAB system of from 220 to 320 degrees, wherein the total amount of iota and kappa carrageenan to the amount of pigment is present in a weight ratio from 1 :5 to 100:1.

Description

ORAL CARE COMPOSITION COMPRISING IOTA CARRAGEENAN AND KAPPA CARRAGEENAN

Field of the Invention

The present invention relates to oral care compositions comprising pigments and polymers that enhance the white appearance of teeth. In particular, the invention is also concerned with the use of such compositions for whitening teeth of an individual.

Background of the Invention

The enamel layer of the tooth is naturally an opaque white or slightly off-white colour. However, this enamel layer can become stained or discoloured. Many products we consume have a negative impact on our teeth and mouth. Many substances can stain or reduce the whiteness of one’s teeth, in particular, certain foods, tobacco products, and fluids such as tea and coffee. These staining and discolouring substances are often able to permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one’s teeth.

Consumers have always had a strong desire for healthy and white teeth. This desire for whiter teeth has given rise to a growing trend in the increased use of tooth whitening products which range from toothpastes to mouthwashes and chewing gums. It has been known in the literature that the whitening effect can also be produced by changing the visual perception of the color of the teeth. For example, the visual perception of a white substance can be altered through the deposition of an optical agent like pigments. However, many oral care products do not provide sufficient deposition of pigments on tooth surfaces. The pigment is simply rinsed away during daily oral hygiene routine such as tooth brushing therefore provide little or no benefits.

There remains a need to develop oral care compositions which can enhance the deposition of pigments on tooth surfaces to maximize the effectiveness of the pigments.

Now it has been found unexpectedly that an oral care composition comprising certain types of carrageenan and anionic surfactants can enhance the deposition of pigments on tooth surfaces to provide instant tooth whitening benefit.

Summary of the Invention

In a first aspect, the present invention is directed to an oral care composition comprising: (a) iota carrageenan;

(b) kappa carrageenan;

(c) an anionic surfactant; and

(d) a pigment having a hue angle, h, in the Cl ELAB system of from 220 to 320 degrees; wherein the total amount of iota and kappa carrageenan to the amount of pigment is present in a weight ratio ((a+b):d) from 1:5 to 100:1.

In a second aspect, the present invention is directed to a packaged oral care product comprising the oral care composition of the first aspect of this invention.

In a third aspect, the present invention is directed to a method of whitening teeth of an individual comprising the step of applying the oral care composition of any embodiment of the first aspect to at least one surface of the teeth of the individual.

All other aspects of the present invention will more readily become apparent upon considering the detailed description and examples which follow.

Detailed Description of the Invention

Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use may optionally be understood as modified by the word “about”.

All amounts are by weight of the final oral care composition, unless otherwise specified. It should be noted that in specifying any ranges of values, any particular upper value can be associated with any particular lower value.

For the avoidance of doubt, 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.

The disclosure of the invention as found herein is to be considered to cover all embodiments as found in the claims as being multiply dependent upon each other irrespective of the fact that claims may be found without multiple dependency or redundancy. Where a feature is disclosed with respect to a particular aspect of the invention (for example a composition of the invention), such disclosure is also to be considered to apply to any other aspect of the invention (for example a method of the invention) mutatis mutandis.

Carrageenan is a family of linear sulfated polysaccharides that are obtained by alkaline extraction from some species of red seaweeds. Carrageenan is formed by disaccharide repeating unit which consists of alternating 3-linked p-d-galactopyranose or 4-linked a-d- galactopyranose or 4-linked 3,6-anhydro-a-d-galactopyranose. The types of carrageenan may be distinguished by their degree of sulfation. There are three major types of carrageenan, which include iota carrageenan, kappa carrageenan, and lambda carrageenan. In all three types of carrageenan molecules, most sugar units have one or two sulfate groups esterified to a hydroxyl group at carbon atoms C2 or C6. Sulfate ester contents range from 18% to 40%. lota carrageenan has a sulfate ester content of from 25 to 34%. Kappa carrageenan has a sulfate ester content of from 18 to 25%. Lambda carrageenan has a sulfate ester content of from 30 to 40%.

Suitable carrageenans for use in the present invention are iota and kappa carrageenan. Preferably the iota carrageenan and the kappa carrageenan in the compositions of the present invention are present in a weight ratio of from 1 :20 to 10: 1 , more preferably from 1 :10 to 5:1 and most preferably from 1 :5 to 3:1. lota carrageenan or kappa carrageenan is commercially available, for example, from CP Kelco.

The total amount of iota and kappa carrageenan in the composition is preferably from 0.01 to 10% by weight of the composition, more preferably from 0.02 to 5% and most preferably from 0.05 to 3%, based on total weight of the oral care composition and including all ranges subsumed therein.

It is preferred if the oral care composition of the present invention is substantially free of other carrageenans in addition to the iota and kappa carrageenans which are included in the composition. “Substantially free of”, as used herein, means less than 0.05%, preferably less than 0.01%, more preferably less than 0.005%, and more preferably still less than 0.001% and most preferably from 0 to 0.001% by weight, based on total weight of the oral care composition, including all ranges subsumed therein. It is particularly preferred if the oral care composition of the present invention does not comprise other carrageenans in addition to the iota and kappa carrageenans. The anionic surfactant suitable for use in the present application includes, for example, sodium, potassium, ammonium, substituted ammonium salts of Cs-C alkyl sulfates (for example sodium lauryl sulfate) or Cs-C ethoxylated alkyl sulfates (for example sodium lauryl ether sulfate), Cs to C alkyl sulphosuccinates (for example dioctyl sodium sulphosuccinate), Cs to C alkyl sulphoacetates (for example sodium lauryl sulphoacetate), Cs to C alkyl sarcosinates (for example sodium lauryl sarcosinate), Cs to C alkyl phosphates (which can optionally comprise up to 10 ethylene oxide and/or propylene oxide units) and sulphated monoglycerides, preferably the anionic surfactant is sodium, potassium, ammonium, substituted ammonium salts of alkyl sulfates having 8 to 18 carbon atoms, more preferably 12 to 18 carbon atoms, particularly preferred anionic surfactant is sodium lauryl sulfate.

The anionic surfactant is preferably present at a level of from 0.01 to 15% by weight of the composition, more preferably from 0.1% to 10%, most preferably from 0.5% to 7%, based on total weight of the oral care composition and including all ranges subsumed therein.

The composition also comprises a pigment. The pigment according to the invention is a shade/material which is insoluble in the relevant medium, at the relevant temperature. This is in contrast to dyes which are soluble. The term “soluble”, as used herein, means a source that dissolves in water to give a solution with a concentration of at least 0.1 moles per litre. The term “relevant medium”, as used herein, refers to human saliva, the liquid medium in which the composition is used, at the temperature of the oral cavity during brushing of the teeth, i.e. up to 37°C. The relevant medium may also be water and the relevant temperature to be 25°C. The only limitation with respect to the pigment is that the same is suitable for use in the mouth.

The pigment has a hue angle, h, in the Cl ELAB system of from 220 to 320 degrees, more preferably from 250 to 290 degrees. A detailed description of hue angles may be found on p57 of Colour Chemistry 3^rd edition by H. Zollinger published by Wiley-VCH. Preferably the pigment is violet or blue, more preferably the pigment is selected from one or more of those listed in the Colour Index International as pigment blue 1 through to pigment 83 and pigment violet 1 through to pigment violet 56. Other suitable pigments are pigment ultramarine blue and ultramarine violet. While the preferred pigment is blue or violet, the same effect may be achieved through mixing pigments outside of this hue angle range. For example, such a hue angle may also be obtained by mixing a red and green-blue pigment to yield a blue or violet shaded pigment.

It is particularly preferred that the pigment is a blue pigment. Some examples of blue pigments suitable for use in this invention include inorganic blue pigments such as iron blue (C.l. 77510) and ultramarine blue (C.l. 77007). A preferred class of blue pigments suitable for use in the invention are organic blue pigments such as phthalocyanine blue pigments. Phthalocyanines are organometallic compounds containing four symmetrically arranged isoindole rings connected in a 16-membered ring linking with alternate carbon and nitrogen atoms. Most phthalocyanines contains a central, coordinated metal ion such as copper. Copper phthalocyanines have the basis structure:

Phthalocyanine blue pigments exhibit more than one crystal modification, which differ in terms of coloristics. Methods have been developed to phase-stabilise the phthalocyanine pigment molecule in order to prevent conversion to a different crystal modification. An example is minor chemical modification of the molecule, for instance partial chlorination. Methods have also been developed to stabilise the phthalocyanine pigment molecule against flocculation during pigment application. An example is admixture of other agents to the molecule, such as surface active additives to the pigment molecule. The following pigments are illustrative phthalocyanine blue pigments preferably included in the composition according to the invention:

It is especially preferred that the pigment is phthalocyanine blue pigment selected from alpha copper phthalocyanines Pigment Blue 15, Pigment Blue 15:1, Pigment 15:2 and mixtures thereof. Most preferably the pigment is Pigment Blue 15:1. A commercially available example is Cosmenyl Blue A4R from Clariant.

The pigment suitable for use in this invention may also be mixtures of any of the above described materials.

The oral care composition of the present invention may comprise other pigments in addition to those described above which are included in the composition. It is preferred that the other pigments are green pigments, more preferably green pigments having a hue angle from 120 to 200 degrees. The preferred green pigment is phthalocyanine green pigment, more preferably Phthalocyanine Green CI-74260. When included, it is preferred that the composition comprises a combination of green and blue pigments. The weight ratio of green pigment to blue pigment is greater than 1 :2, preferably greater than 2:3, more preferably from 2:3 to 3:2.

The oral care composition of the present invention typically comprises from 0.001 to 1% by weight of the pigment, more preferably from 0.01 to 0.5%, and most preferably from 0.02 to 0.2%, based on total weight of the oral care composition and including all ranges subsumed therein.

The total amount of iota and kappa carrageenan to the amount of pigment is present in the composition in a weight ratio from 1 :5 to 100:1 , preferably from 1 :5 to 50:1 and more preferably from 1 :3 to 40:1, and most preferably from 1 :1 to 30:1, including all ratios subsumed therein. The oral care composition of the invention may comprise other polymeric materials in addition to the carrageenans which are included in the composition. Particularly preferred polymeric materials include copolymers of methyl vinyl ether and maleic anhydride, high molecular weight PEGs, high molecular weight cellulose ethers or mixtures thereof. “High molecular weight”, as used herein, means the polymeric material has a molecular weight of at least 100,000 g/mol, preferably at least 200,000 g/mol. Copolymers of methyl vinyl ether and maleic anhydride are especially preferred, which are commercially available under the trade name GANTREZ™.

Preferably, the oral care composition has a pH from 4.0 to 10.0, more preferably from 5.0 to 9.0, and most preferably from 5.5 to 8.0. The pH of oral care composition is measured when 5 parts by weight of the composition is uniformly dispersed and/or dissolved in 20 parts by weight pure water at 25°C. In particular, the pH may be measured by manually mixing 5 g oral care composition with 20 mL water for 30 s, then immediately testing the pH with indicator or a pH meter.

The oral care composition may comprise other surfactants in addition to the anionic surfactants. Suitable surfactants include non-ionic surfactants, such as polyethoxylated fatty acid sorbitan esters, ethoxylated fatty acids, esters of polyethylene glycol, 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. Mixtures of any of the above described materials may also be used.

Preferably, the oral care composition is an aqueous composition. The water content is at least 1.5% by weight of the composition, preferably at least 5%, more preferably at least 10%. It is preferable that the water content is from 1.5 to 95% by weight of the composition, more preferably from 5 to 90% and most preferably from 10 to 90%, based on total weight of the composition and including all ranges subsumed therein.

The oral care composition of the present invention may comprise a physiologically acceptable carrier. The carrier preferably comprises at least thickener, humectant or a combination thereof.

Thickener may be used in this invention and is limited only to the extent that the same may be added to a composition suitable for use in the mouth. Illustrative examples of the types of thickeners that may be used in this invention include, sodium carboxymethyl cellulose (SCMC), hydroxyl ethyl cellulose, methyl cellulose, ethyl cellulose, gum tragacanth, gum arabic, gum karaya, sodium alginate, guar, xanthan gum, starch, modified starch, silica based thickeners including silica aerogels, magnesium aluminum silicate (e.g., Veegum), Carbomers (cross-linked acrylates) and mixtures thereof.

Typically, xanthan gum and/or sodium carboxymethyl cellulose and/or a Carbomer is/are preferred. When a Carbomer is employed, those having a weight-average molecular weight of at least 700,000 are desired, and preferably, those having a molecular weight of at least 1,200,000, and most preferably, those having a molecular weight of at least about 2,500,000 are desired. Mixtures of Carbomers may also be used herein.

In an especially preferred embodiment, the Carbomer is Synthalen PNC, Synthalen KP or a mixture thereof. It has been described as a high molecular weight and cross-linked polyacrylic acid and identified via CAS number 9063-87-0. These types of materials are available commercially from suppliers like Sigma.

In another especially preferred embodiment, the sodium carboxymethyl cellulose (SCMC) used is SCMC 9H. It has been described as a sodium salt of a cellulose derivative with carboxymethyl groups bound to hydroxy groups of glucopyranose backbone monomers and identified via CAS number 9004-32-4. The same is available from suppliers like Alfa Chem.

In another especially preferred embodiment, the thickener is xanthan gum.

Thickener typically makes up from 0.01 to about 10%, more preferably from 0.1 to 9%, and most preferably, from 0.1 to 5% by weight of the oral care composition, based on total weight of the composition and including all ranges subsumed therein.

Suitable humectants are preferably used in the oral care composition of the present invention and they include, for example, glycerin, sorbitol, propylene glycol, dipropylene glycol, diglycerol, triacetin, mineral oil, polyethylene glycol (preferably, PEG-400), alkane diols like butane diol and hexanediol, ethanol, pentylene glycol, or a mixture thereof. Glycerin, polyethylene glycol, sorbitol or mixtures thereof are the preferred humectants. The humectant may be present in the range of from 10 to 90% by weight of the oral care composition. More preferably, the carrier humectant makes up from 25 to 80%, and most preferably, from 30 to 60% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

The carrier is typically present at a level of from 10 to 90% by weight of the oral care composition, more preferably 25 to 80%, and most preferably from 30 to 70% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

The oral care composition may comprise a fluoride source. Preferred fluoride source includes sodium fluoride, stannous fluoride, potassium fluoride, sodium monofluorophosphate, sodium fluorosilicate, ammonium fluorosilicate, amine fluoride, ammonium fluoride or mixtures thereof. Preferably, the fluoride source is stannous fluoride, sodium fluoride, sodium monofluorophosphate or mixtures thereof. Sodium monofluorophosphate is particularly preferred. The fluoride source may be present at a level from 0.01 to 10%, more preferably from 0.03 to 5% and most preferably from 0.1 to 2% by weight of the oral care composition, based on total weight of the composition and including all ranges subsumed therein.

The oral care composition may comprise abrasives. Preferred abrasives include silicas, aluminas, calcium carbonates, dicalcium phosphates, calcium pyrophosphates, hydroxyapatites, trimetaphosphates, insoluble hexametaphosphates or mixtures thereof, including agglomerated particulate abrasives. Calcium carbonate and silica are particularly preferred, especially silica. The abrasives may be present in the range of from 0.01 to 60%, more preferably from 0.1 to 30%, and most preferably from 1 to 15% by weight of the oral care composition, based on total weight of the composition and including all ranges subsumed therein.

The oral care composition of the present invention may contain a variety of other ingredients which are common in the art to enhance physical properties and performance, in addition to pigments which are included in the composition. These ingredients include antimicrobial agents, anti-inflammatory agents, anti-caries agents, plaque buffers, dyes, vitamins, plant extracts, desensitizing agents, anti-calculus agents, biomolecules, flavors, proteinaceous materials, preservatives, opacifying agents, pH-adjusting agents, sweetening agents, polymeric compounds, buffers and salts to buffer the pH and ionic strength of the compositions, and mixtures thereof. Such ingredients typically and collectively make-up less than 20% by weight of the composition, and preferably, from 0.0 to 15% by weight, and most preferably, from 0.01 to 12% by weight of the composition, including all ranges subsumed therein.

The oral care composition of this invention can be used in a method of whitening the teeth of an individual comprising applying the composition to at least one surface of the teeth of the individual. Preferably, the method is non-therapeutic. The oral care composition of this invention may additionally or alternatively be for used for whitening the teeth of an individual, and/or used in the manufacture of a medicament in whitening teeth of an individual. Preferably, the use is non-therapeutic.

Typically, the composition will be packaged. In toothpaste or gel form, the composition may be packaged in a conventional plastic laminate, metal tube or a single compartment dispenser. The same may be applied to dental surfaces by any physical means, such as a toothbrush, fingertip or by an applicator directly to the sensitive area. In liquid mouthwash form the composition may be packaged in a bottle, sachet or other convenient container.

The oral care composition of the invention is preferably a toothpastes or gel. When the oral care composition is a toothpaste or gel, the same typically has a viscosity from about 30,000 to 180,000 centipoise, and preferably, from 60,000 to 170,000 centipoise, and most preferably, from 65,000 to 165,000 centipoise, taken at room temperature (25°C) with a Brookfield Viscometer, Spindle No.93/94 and at a speed of 5 rpm for 1 minute.

The composition can be effective even when used in an individual’s daily oral hygiene routine. For example, the composition may be brushed onto the teeth and/or be rinsed around the inside of the mouth of the individual. The composition may, for example, be contacted with the teeth for a time period of one second to 20 hours. More preferably from 1 s to 10 hours, more preferably still from 10 s to 1 hour and most preferably from 30 s to 5 minutes. The composition may be used daily, for example for use by an individual once, twice or three times per day.

The following examples are provided to facilitate an understanding of the present invention. The examples are not provided to limit the scope of the claims. Examples

Example 1

This example demonstrated the effect of carrageenans on deposition of pigments. All ingredients are expressed by weight percent of the total formulation, and as level of active ingredient.

TABLE 1 a. Dispersion of C.l. 74160 (pigment blue 15:1) in water/glycerol underthe trade name Cosmenyl Blue A4R from Clariant.

Methods

To evaluate the deposition of pigments, the following in vitro test was performed.

Hydroxyapatite (HAP) discs were used as substrates. Four HAP discs were used for each sample. Each HAP disc was soaked in de-ionized (DI) water for 1 hour. After soaking, the HAP disc was immersed directly in a test sample (6 mL) for 24 hours. Then the disc was taken out and rinsed with 40 mL DI water for 6 times. The residual water on the disc was absorbed with tissue. The L*, a*, b* values of each HAP disc were measured using DigiEye (VeriVide, England). The colour difference expressed as the CIELAB delta E (AE) value was calculated based on L*, a*, b* values measured using DigiEye with the following formula:

AE = AL² + Aa² + Ab²

AL = L1-L0, Aa = a1 - aO, Ab = b1 - bO, where L1 , a1 and b1 are the color indexes of HAP discs treated by samples, and L0, aO and bO are the color indexes of blank HAP discs.

Results

The results are summarized in table 2. The higher the delta E value, the more deposition of the pigment. TABLE 2

Sample 1 comprising both iota and kappa carrageenan had higher delta E value compared to other samples, which indicated better deposition of the pigment.

Example 2

This example demonstrated tooth whitening benefit in full formulations. All ingredients are expressed by weight percent of the total formulation and as level of active ingredient.

TABLE 3

Methods

A polymer/glycerol solution (DAV diluent) was prepared by combining the ingredients in Table 4, and it was used to mimic the viscosity characteristics of saliva.

TABLE 4 The test sample was mixed with water and DAV diluent at a weight ratio of 1:1:1 to form a toothpaste slurry.

To evaluate tooth whitening efficacy of the samples, the following in vitro test was performed. The WIO index is an index which has been optimized specifically for the evaluation of whiteness in teeth (as described in Journal of Dentistry, volume 36, Supplement 1 , 2008, pages 2 to 7). Changes in whiteness was calculated based on L*, a*, b* values which were measured using DigiEye (VeriVide, England).

Sixteen human enamel blocks were used for each sample. The baseline L*, a*, b* of the enamel blocks was measured by DigiEye. The enamel blocks were brushed for one minute with the toothpaste slurry on a WIRA® brushing machine equipped with toothbrushes. The load of the tooth brushing was 175 g and the automatic brushing operated at a speed of 150 rpm. Thereafter the enamel blocks were rinsed twice each time with 20 mL water by the brushing machine. The residual water on the enamel blocks was absorbed with tissue. After this step the L*, a*, b* values of each enamel block were re-measured based on which the changes in WIO values (A WIO) from baseline were calculated.

Results

The results are summarized in table 5.

TABLE 5

Sample 2 comprising both iota and kappa carrageenan showed better tooth whitening efficacy than samples C and D.

Claims

1. An oral care composition comprising:

(a) iota carrageenan;

(b) kappa carrageenan;

(c) an anionic surfactant; and

2. The oral care composition according to claim 1, wherein the total amount of iota and kappa carrageenan to the amount of pigment is present in a weight ratio from 1:5 to 50: 1 , preferably from 1 :3 to 40: 1.

3. The oral care composition according to claim 1 or claim 2, wherein the total amount of iota and kappa carrageenan in the composition ranges from 0.01 to 10% by weight of the composition, preferably from 0.02 to 5%.

4. The oral care composition according to any of the preceding claims, wherein the iota carrageenan and the kappa carrageenan are present in the composition in a weight ratio of from 1 :20 to 10:1 , preferably from 1 : 10 to 5: 1.

5. The oral care composition according to any of the preceding claims, wherein the anionic surfactant is sodium, potassium, ammonium, substituted ammonium salts of alkyl sulfates having 8 to 18 carbon atoms, preferably 12 to 18 carbon atoms.

6. The oral care composition according to claim 5, wherein the anionic surfactant is sodium lauryl sulfate.

7. The oral care composition according to any of the preceding claims, wherein the composition comprises from 0.01 to 15% by weight of the anionic surfactant, preferably from 0.1 to 10%.

8. The oral care composition according to any of the preceding claims, wherein the pigment has a hue angle, h, in the Cl ELAB system of from 250 to 290. The oral care composition according to any of the preceding claims, wherein the pigment is a blue pigment, preferably a phthalocyanine blue pigment. The oral care composition according to claim 9, wherein the phthalocyanine blue pigment is selected from alpha copper phthalocyanines Pigment Blue 15, Pigment Blue 15:1 , Pigment Blue 15:2 and mixtures thereof, preferably Pigment Blue 15:1. The oral care composition according to any of the preceding claims, wherein the composition comprises from 0.001 to 1% by weight of the pigment, preferably from 0.01 to 0.5%. The oral care composition according to any of the preceding claims, wherein the composition is substantially free of other carrageenans in addition to the iota carrageenan and the kappa carrageenan. The oral care composition according to any of the preceding claims, wherein the composition further comprises green pigments, preferably phthalocyanine green pigment. The oral care composition according to any of the preceding claims, wherein the composition is an aqueous composition. A method of whitening teeth of an individual comprising the steps of applying the composition according to any of the preceding claims to at least one surface of the teeth of an individual.