EP3518865A1

EP3518865A1 - Cleaning composition

Info

Publication number: EP3518865A1
Application number: EP17769110.2A
Authority: EP
Inventors: Pierre Starck; Simeon Dobrev Stoyanov; Vesselin Nikolaev Paunov; Anupam A K DAS
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2016-10-03
Filing date: 2017-09-26
Publication date: 2019-08-07
Also published as: CN109789059A; BR112019006214A2; WO2018065264A1

Abstract

A cleaning composition comprising, oil, oil-dissolvable surface modifier having a HLB value of less than 7, polar liquid, and abrasive cleaning agent, wherein the oil- dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent, wherein the concentration of anionic surfactant in the composition is less than 1.5 wt%.

Description

CLEANING COMPOSITION

The present invention relates to a cleaning composition, it further relates to a process to prepare said cleaning composition.

Background of the Invention Abrasive cleaning compositions are prepared and used since a long time. They comprise an abrasive agent, like calcium carbonate, and surfactant. The abrasive agent helps removing dirt from a surface and preferably polishing the surface. In addition, the abrasive agent functions as a texture builder of the cleaning composition. Hence, a significant amount of abrasive agent may be required, to provide a desired viscosity to the product. For example, in toothpaste, the amount of abrasive agent is about 50 wt% in commercial toothpaste, in the form of calcium carbonate. There is a desire to reduce this amount, as the price of the product will be less, while maintaining the desired viscosity. Abrasive cleaning compositions normally comprise surfactant. Surfactants help in the cleaning process, and cause foaming during use of the composition, especially non- ionic and anionic surfactants. Foaming is experienced by the user that the cleaning composition is actually active. However, surfactants can be irritant to the skin of the user. Especially in case the abrasive cleaning composition is a toothpaste, surfactants can irritate the gum. The use of surfactants, in particular in toothpaste, further has the disadvantage that integration of possible pigment microparticles is challenging, as surfactant prevents effective deposition on the surface, e.g. the tooth enamel surface.

A reduced use or even absence of surfactant in the cleaning composition is therefore desired, but not at the cost of foaming.

There is a need for an abrasive cleaning composition which allows for the reduction or even absence of surfactant while maintaining foaming, and allows for the use of less abrasive agent while maintaining viscosity. Summary of the Invention

Surprisingly, this objective was achieved by a cleaning composition comprising:

Oil,

· Oil-dissolvable surface modifier having a HLB value of less than 7,

• Polar liquid,

• Abrasive cleaning agent,

wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent,

wherein the concentration of anionic surfactant in the composition is less than 1 .5 wt%.

In a further aspect, the present invention relates to a process for preparing a composition according to the invention, the process comprising the step of providing a mixture comprising polar liquid, abrasive cleaning agent, oil, and oil-dissolvable surface modifier, wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent.

In a further aspect the present invention relates to the use of a composition of the invention as a dentifrice.

Description of the Figure

Figure 1 shows photographs of (a) commercial toothpaste, (b) 25% (w/v) in-situ hydrophobised calcium carbonate particles in water containing 0.8% (v/v) guar gum, the same sample after the addition of 1 % (c) and 1.5% (d) (w/v) secondary phase (50:50 (v/v) oleic acid and peppermint oil).

Detailed Description of the Invention

Suspension

The composition of the invention preferably comprises, more preferably is, an emulsion of an oil phase in a polar phase. It comprises abrasive cleaning agent. The polar phase normally, and preferably comprises a polar liquid, normally and preferably water or glycerol. The polar liquid employed in the present process can be pure liquid or a mixture of liquids. The polar liquid may further contain one or more dissolved or dispersed components. The composition preferably contains 40 to 90 wt.% of the total composition of polar liquid. More preferably, the composition contains 50 to 80 wt.% of the total composition of the polar liquid.

The polar liquid may contain 50 to 100 wt.% water. More preferably the polar liquid contains 70 to100 wt% water, even more preferably 90 to 100 wt.% of water, most preferably the polar liquid is water. The water content of the composition preferably lies in the range of 50 to 85 wt.%, more preferably of 50 to 70 wt.%, based on the weight of the composition. In the case of glycerol the polar liquid contains 10 wt.% or less water.

The polar phase is preferably liquid, as understood. The polar phase is normally, as understood by the skilled person, and preferably, immiscible with the oil phase. In this way, the polar phase is preferably the continuous phase. The composition preferably is a water-continuous suspension. Preferably, the polar phase, e.g. the polar liquid, preferably water, comprises the abrasive agent. Consequently, it is preferred that the oil-phase does not comprise abrasive agent. More than 95 wt% of the abrasive agent is preferably suspended in the polar phase, e.g. water.

The composition is preferably a water-based capillary suspension. Capillary suspensions are known in the art. Preferably, it is a capillary suspension wherein a small amount of immiscible liquid is in a continuous phase. The oil phase comprises the oil and a hydrophobic surface modifier with an HLB value of less than 7.

In the present context, the capillary suspension comprises an oil phase, comprising oil and surface modifier with an HLB value of less than 7, preferably in a total amount of less than 4 wt% (based on the weight of the composition) and it comprises a continuous polar phase, preferably comprising water. Without willing to be bound to theory, it is believed that the secondary phase, the oil phase, forms and/or stabilises a network with particles. In the context of the present invention the particles are the abrasive agent. The particles are hydrophilic. Therefore, preferably, the cleansing composition is a water-continuous capillary emulsion. Abrasive agent

The composition comprises abrasive agent. The abrasive agent is in the form of particles, which particles are preferably hydrophilic. They are preferably present in the polar liquid. The particles can be abrasive agents as known in the art of abrasive cleaning compositions, preferably in the field of dentifrices. The abrasive agent can for example comprise silica, alumina, calcium carbonate, calcium silicate, dicalcium phosphate, calcium pyrophosphate, hydroxyapatite, trimetaphosphate, insoluble hexametaphosphate, including agglomerated particulate abrasive agents. In particular, it is preferred when the abrasive agent comprises silica (preferably amorphous hydrated silica), calcium carbonate or a mixture thereof, preferably calcium carbonate, as this provided optimal texture and rheology of the composition in the context of the invention.

Other abrasives that can be preferred are:

· a phosphate-type abrasive (such as calcium secondary phosphate dehydrate, calcium secondary phosphate nonhydrate and calcium pyrophosphate),

• aluminas, aluminium hydroxide,

• titanium dioxide, crystalline zirconium silicate, polymethyl methacrylate, insoluble calcium metasilicate, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, magnesium tertiary phosphate, zeolite, zirconium silicate, calcium tertiary phosphate, hydroxyapatite, fluoroapatite, calcium-deficient apatite, calcium tertiary phosphate, calcium quaternary phosphate, calcium octanary phosphate and abrasives of a synthetic resin type. One of them may be used solely or two or more thereof may be used jointly.

The particle size of the abrasive agent is preferably of between 0.05 to 30 micrometer, preferably of from 0.1 and 30 micrometer, more preferably of between 0.5 and 25 micrometers and most preferably of between 5 and 20 micrometers. Probably at least 80 wt%, more probably at least 90% of the abrasive agent has this particle size.

The amount of abrasive agent is preferably of between 10 and 60 wt%, more preferably of between 10 and 50 wt%, based on the total weight of the composition. An advantage of the present invention is that a desired viscosity of the cleaning

composition, especially if the cleaning composition is a dentifrice, is maintained while the amount of abrasive agent is reduced. Hence, an even more preferred amount of abrasive agent is of between 20 and 30 wt%, more preferably of between 22 and 20 to 40 wt%, or even 20 to 30 wt%, calcium carbonate. The relatively lower concentrations of abrasive agent, like calcium carbonate, are preferably in combination with relatively higher levels of secondary oil phase or relatively higher levels of a hydrophobizing agent. It may be preferred, that at lower concentrations the thickener (polymers, gums) in the aqueous phase (e.g. guar gum) is added for more texture but this may affect the foamability of the composition.

Preferably, hydrophilic abrasive agent particles are used. When present in the composition, these agent particles become hydrophobised. The nature of the agent as being hydrophyllic, applies for the material before addition into the composition.

It is possible that the composition comprises further hydrophobic particles, or pre- hydrophobized particles, for example to increase the foaming. It can be preferred however, that hydrophobic particles, or pre-hydrophobized particles are absent, as they are difficult to disperse in the polar phase during manufacturing of the composition of the invention.

Oil

The composition of the invention comprises oil. Without willing to be bound to theory, the function of the oil in the present invention is to form capillary bridges between the solid particles which may be abrasive. The oil is liquid at 30 °C, preferably at 20 °C.

The oil is preferably a fragrance oil, and can be natural or a synthetic oil. The oil is preferably selected from the group consisting of peppermint oil, spearmint oil, anis oil, eucalyptus oil, wintergreen oil, isopropyl myristate and mixtures thereof, especially in case the composition is an oral care composition. The oil can preferably comprise isopropyl myristate, especially in combination with oleic acid present in or as being the surface modifier.

The amount of oil is preferably less than 2 wt%, preferably less than 1.5 wt% more preferably less than 1 wt% of the total composition, most preferably less than 0.8 wt%, based on the total weight of the composition. It is preferably more than 0.1 wt%, more preferably more than 0.2 wt%, even more preferably more than 0.3 wt% and even more preferably more than 0.7 wt%., based on the total weight of the composition. It can be preferred to range between 0.1 and 2 wt%, preferably between 0.2 and 1 .5 wt%, most preferably of between 0.2 and 1.0 wt%, based on the total weight of the composition. Surface modifier

The composition comprises a surface modifier with an HLB value of below 7. The surface modifier modifies the particle surface, and is preferably a solid-surface modifier. The surface modifier is preferably oil-dissolvable. The surface modifier is insoluble in the polar liquid, preferably water, and is preferably selected from the group consisting of hydrophobic polymers, surfactants, organic acids and mixtures thereof. The surface modifier is chemically attracted to or bound to the abrasive cleaning agent, preferably via covalent or non-covalent interaction. The interaction is preferably via electrostatic interaction, such as for example ionic interaction or hydrogen bonds; Van der Waals interaction, or via covalent bonds. Preferably, the oil-dissolvable surface modifier is chemically attracted to the abrasive cleaning agent via ionic interaction. In a typical situation, the surface modifier accesses the particle surface through the oil, typically in the form of oil drops, which form capillary bridges between the particles dispersed in the polar liquid.

For example, in case the abrasive agent is CaCC , which is a cationic compound, the surface modifier is preferably an anionic compound, such as a fatty acid, preferably oleic acid, palmitic oleic or stearic acid, more preferably oleic acid. Especially if the abrasive agent is calcium carbonate, the solid surface modifier preferably is chosen from the group consisting of long chain fatty acids (i.e. having a carbon chain of 14 or longer), preferably from the group consisting of oleic acid, palmitic acid, stearic acid, and most preferably, the solid surface modifier is oleic acid.

In case the abrasive agent is anionic, such as for example S1O2, the surface modifier is preferably cationic, such as for example isopropylmeristate. Especially for calcium silicate or silica particles, the surface modifier can be oil-soluble quaternary ammonium surfactants like octadecyl trimethyl ammonium bromide (ODTAB), etc. The particles can be pre-hydrophobised with this agent. In such a case, the oil-soluble quaternary ammonium surfactant can be delivered to the surface of the particles (e.g. calcium silicate) by using an ethanol solution, followed by drying the ethanol before adding the secondary oil phase. This proved suitable for negatively charged particles, like

CaSiOs, Si0₂, etc.

The amount of solid surface modifier is preferably of less than 2 wt%, more preferably of less than 1.5 wt%, even more preferably less than 1 wt%, even more preferably less than 0.8 wt%, based on the total weight of the composition. It is preferably present in an amount of more than 0.1 wt%, more preferably of more than 0.2 wt%, even more preferably more than 0.3 wt%, even more preferably more than 0.7 wt%, based on the total weight of the composition. Preferred ranges are of between 0.1 to 2 wt% more preferably of from 0.5 to 1 .0 wt%, even more preferably 0.7 to 0.9 wt%, based on the total weight of the composition.

It is preferred, that the amount of solid surface modifier is from 1 to 50 wt%, preferably of from 5 to 30 wt% based on the weight of the oil. The secondary phase or oil-phase, comprising the combined amount of oil and solid surface modifier, is preferably of between 1 and 4 wt%, more preferably of between 1 .5 and 3 wt%, more preferably of between 1 and 2.5 wt%, based on the total weight of the composition. The skilled person understands that when a gum is present, relatively lower levels of secondary phase can be used. It can be preferred that a lower level of 0.8 wt% of the total composition is used.

Surfactant

The present invention allows to reduce the level of surfactant, in particular anionic surfactants, while maintaining foaming. As described, this can be beneficial to reduce irritation of the gum. Surfactant, e.g. anionic surfactant, can be absent. The concentration of surfactant is preferably less than 1 .5 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, even more preferably less than 0.1 wt%, based on the total weight of the composition. Preferably, the concentration of nonionic surfactant is less than 1 .5 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, even more preferably less than 0.1 wt%, based on the total weight of the composition.

Preferably, the concentration of anionic surfactant is less than 1 .5 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, even more preferably less than 0.1 wt%, based on the total weight of the composition.

Solid surface modifier, preferably oil-soluble quaternary ammonium surfactants like ODTAB, as described above, is preferably not counted for as 'surfactant' in the context of the invention. Rheology modifier

The composition can comprise a rheology modifier, such as a gum. In this context, abrasives are not counted as rheology modifier. The concentration of rheology modifier, preferably a gum, is preferably lower than 3 wt%, preferably lower than 1 wt%, more preferably lower than 0.1 wt%, based on the weight of the composition. It can be preferred, that gum is absent. Gum appears to have a negative effect on foam formation.

It can be preferred that a rheology modifier, such as a gum, is present. Especially in case the cleaning composition is a dentifrice, it is preferred that during the tooth brushing the composition does not become too liquid and easily leaks away from the mouth. This risk can result from shear thinning effects during brushing. A gum can reduce this effect. If present, gum is preferably present in an amount of between 0.1 and 1 wt%, more preferably of between 0.2 and 0.9 wt%, based on the weight of the composition. In case gum is present, gum is preferably guar gum or homo- and copolymers of acrylic acid crosslinked with a polyalkenyl polyether, sold as Carbopol™, or a mixture thereof. Guar gum is preferred. Xanthan gum is less desired, or more preferably absent, as it showed a negative effect on foam formation. If present, its concentration is preferably less than 0.1 wt% of the total composition.

Suitably, the composition of the invention has a rheology in the form of a paste, preferably such as toothpaste. To provide such a rheology, the amount of abrasive agent can be significantly lower than in conventional cleaning compositions or dentifrices, respectively. A rheology modifier, such as a texturing agent, like a gum, becomes less needed or superfluous.

The skilled person will understand that the rheology of composition relates to both the concentration of abrasive agent and the stability of the network formed by the oil and the surface modifier with HLB value lower than 7. So, lower levels of abrasive agent require higher levels of oil and surface modifier, and for higher levels of abrasive agent lower oil and surface modifier are sufficient, to provide a texture as desired, e.g. similar to tooth paste. Miscellaneous

The composition is preferably an oral care composition, most preferably a dentifrice. The pH of the composition is preferably of from 7.5 to 8.5 at 20°C.

The composition may include ingredients to enhance the performance in use, for example to the use as a dentifrice. Such ingredients include colour, fragrance, enzymes, bleaching agents, fluoride, freeze-thaw stabilisers, bactericides,

preservatives, hydrotropes and perfumes.

It can be in particularly preferred, that the composition comprises a pigment. Such is in particular advantageous in case the composition is a dentifrice. As the composition of the invention allows for the use of a low concentration of surfactant, or even the absence of surfactant, the composition of the invention provides for enhanced attachment of pigment to the surface to be cleaned, preferably to the teeth. The composition preferably comprises a compound selected from the group consisting of Ti02, Mica, covarine blue (W6795) and mixtures thereof. The amount of pigment is preferably from 0.01 to 0.3 wt%, preferably from 0.02 to 0.1 wt%, more preferably from 0.03 to 0.08 wt%. The amount does refer to the amount of actives, not to any carrier material in the pigment suspension.

Process

In a further aspect, the present invention relates to a process to prepare a composition of the invention. The process preferably comprises the step of providing a mixture comprising polar liquid, abrasive cleaning agent, oil, and oil-dissolvable surface modifier, wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent.

The amounts of ingredients used in the process are the same as those mentioned in the description of the composition, and based on the weight of the composition resulting from the process, unless otherwise indicated.

The process preferably comprises the steps of:

a) Providing a mixture of abrasive cleaning agent and polar liquid, preferably water, b) Mixing oil and oil-dissolvable surface modifier having an HLB of less than 7 into the mixture resulting from step a). In step a) a mixture is made of abrasive cleaning agent with polar liquid. It can be preferred that a texturiser, preferably a gum is mixed with the polar liquid and abrasive material. The gum is preferably at a concentration of less than 3 % of the total composition.

Mixing is conveniently done by a mixing apparatus known in the art.

In a step b), the mixture of polar liquid, abrasive cleaning agent and optionally texturizing agent such as gum, is combined with oil and surface modifier with an HLB of below 7. It can be preferred that first oil is combined with the mixture resulting from step a) and then the surface modifier with an HLB of below 7 is combined with the mixture comprising polar liquid, abrasive cleaning agent, optional texturizing agent such as gum, and oil. It may also be preferred, to add the oil and the surface modifier with an HLB of below 7 together to the mixture comprising polar liquid and abrasive cleaning agent, for example in the form of a pre-mix.

It may be preferred, to add further ingredients to the composition, wherein water- soluble ingredients are added to the polar liquid and oil-soluble material is added to the oil, before combining the oil and the polar liquid.

The invention further relates to a composition obtainable by, preferably obtained by, the process according to the invention. The composition preferably comprises less than 1.5 wt% anionic surfactant, more preferably is free of anionic surfactant. Use

In a further aspect, the present invention relates to the use of the composition of the invention as a dentifrice.

The invention will now be exemplified by the following non-limiting examples. Examples

Experimental

Formulation of surfactant free toothpaste using water-based capillary suspensions.

The Solvay Socal 31 calcium carbonate hydrophilic particles (Salin de Giraud, France) respectively was used for making these capillary suspensions. The continuous phase used was Milli Q water. The Guar gum FG60-70 was obtained from Multi-kern

Corporation, NJ, USA. The secondary phase used was pure oleic acid (10588810, Fisher Scientific, UK) and peppermint oil purified by triple distillation (W284823, Sigma Aldrich, UK). The particles (25 w/v) are mixed into the bulk fluid (water containing guar gum) using a propeller stirrer at 500 rpm for 5 minutes. The dispersion was then mixed with minute amounts of secondary phase oleic acid and peppermint oil (initially mixed at 50:50 ratio) using the same stirrer.

Foaming studies of the surfactant free toothpaste formulations

The foaming capability and stability was measured. 5 g of samples with 30 ml of water was hand shaken for 20 seconds in a 100 ml measuring cylinder. The foam height was then measured at various times in order to observe the foam stability. The produced foam was also observed under the microscope in order to observe its shape, size and structure.

Formulation of surfactant free toothpaste using water based capillary suspensions The following compositions were prepared:

1 2 3 4

(comparative) (comparative)

Commercial

toothpaste

Peppermint oil - 0.5 % w/v 0.75 % w/v

Oleic acid - 0.5 % w/v 0.75 % w/v in-situ 25 % w/v 25 % w/v 25 % w/v hydrophobised

CaC03

particles

Guar gum 0.8 %v/v 0.8 %v/v 0.8 %v/v water rest rest rest Results

Appearance and foam characteristics of the compositions were compared and results are depicted in the table below.

Conclusion

Composition 1 is a commercial toothpaste (Colgate) with a toothpaste rheological appearance (figure 1 , left upper panel). Composition 2 does not contain a secondary phase, resulting in a very soft to liquid appearance. The low level of particles

(compared to commercial toothpaste) combined with 0.8% gum was not sufficient to reach the desired texture. Composition 3 showed a texture similar to that of toothpaste, despite a relatively low level of particles. Composition 4 showed that at an amount of 1 .5% secondary phase and a particle level of 25%, and a gum level of 0.8 % the texture becomes too hard. This indicates that the skilled person may vary the viscosity building components of particle concentration, secondary phase level and gum concentration to create a texture that fits his or her need. All compositions have a particle level lower than that of commercial toothpaste, and foam at a level that is acceptable for toothpaste purposes, despite the absence of anionic surfactant.

Formulation of surfactant free toothpaste using glycerol based capillary suspensions

5 6 7 8

Isopropyl 0.18% w/v 3.9% w/v 1.8 w/v 0.36 w/v myristate

Oleic acid 0.02% w/v 0.1 % 0.2 w/v 0.04 w/v in-situ 30% w/w 10% w/v 20%w/v 20 %w/v hydrophobised

CaC03

particles

Glycerol To 100 To 100 To 100 To 100

Claims

1. A cleaning composition comprising:

• oil,

• oil-dissolvable surface modifier, having a HLB value of less than 7,

• polar liquid,

• abrasive cleaning agent,

wherein the concentration of anionic surfactant in the composition is less than 1.5 wt% of the total composition.

2. Composition according to claim 1 , wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent via covalent or non-covalent interaction, preferably via:

• Electrostatic interaction, e.g. ionic interaction or hydrogen bonds,

Van der Waals interaction, or

• Covalent bonds.

3. Composition according to any one of the preceding claims, wherein the oil- dissolvable surface modifier is chemically attracted to the abrasive cleaning agent via ionic interaction.

4. Composition according to any one of the preceding claims, wherein

• Oil is present in an amount of 2 wt% or less, based on total weight of the composition,

• oil-dissolvable surface modifier is present in an amount of from 1 to

50 wt%, preferably 5 to 30 wt% based on the weight of the oil,

• abrasive cleaning agent is present in an amount of from 10 to 60 wt%, preferably 10 to 50 wt%, more preferably of from 20 to 30 wt% based on total weight of the composition.

5. Composition according to any one of the preceding claims, wherein the oil is present in an amount of 1 wt% or less, more preferably 0.5 wt% or less based on total weight of the composition.

6. Composition according to any one of the preceding claims, wherein the oil, surface modifier and abrasive cleaning agent are present as a network, preferably wherein the composition is in the form of a capillary emulsion.

7. Composition according to any one of the preceding claims, wherein the abrasive cleaning agent are particles of a material selected from the group consisting of CaC03, calcium silicate and Si02.

8. Composition according to any one of the preceding claims, wherein the

concentration of gum is lower than 3 wt%, preferably lower than 1 wt%, more preferably is present in an amount of from 0.1 to 1 wt%, even more preferably is present in an amount of from 0.2 to 0.9 wt%, most preferably wherein gum is absent (wt% based on volume of the water).

9. Composition according to claim 8, wherein the gum is guar gum.

10. Composition according to any one of the preceding claims, wherein if the

abrasive cleaning agent is:

• Cationic, the surface modifier comprises a long chain fatty acid, preferably oleic acid, stearic acid or palmitic acid,

• Anionic, the surface modifier comprises isopropyl myristate.

1 1. Composition according to any one of the preceding claims, wherein the

composition comprises one or more of ΤΊ02, Mica, Blue covarine.

12. Composition according to any one of the preceding claims, wherein the

composition is a dentifrice.

13. Process for preparing a composition according to any one of the preceding claims, the process comprising the step of providing a mixture comprising polar liquid, abrasive cleaning agent, oil, and oil-dissolvable surface modifier, wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent.

14. Process according to claim 13, wherein the process comprises the steps of a) Providing a mixture of abrasive cleaning agent and polar liquid, b) Mixing oil into the mixture resulting from step a),

c) Mixing an oil-dissolvable surface modifier with HLB lower than 7 to the mixture resulting from step b), wherein the oil-dissolvable surface modifier is chemically attracted to or bound to the abrasive cleaning agent.

15. Process according to claim 14, wherein the polar liquid comprises a dissolved gum in an amount of less than 3 wt% of the total composition.