WO2020035376A1

WO2020035376A1 - Gel compositions

Info

Publication number: WO2020035376A1
Application number: PCT/EP2019/071257
Authority: WO
Inventors: Giovanni Francesco Unali
Original assignee: Unilever Plc; Unilever N.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2018-08-13
Filing date: 2019-08-07
Publication date: 2020-02-20
Also published as: WO2020035379A1; WO2020035369A1; WO2020035377A1

Abstract

The present invention is concerned with gel composition suitable for making a homecare or personal care product, the gel composition comprising a thickener selected from hydroxypropyl methylcellulose (HPMC) and gelatin; a low boiling point non-aqueous liquid 10 medium, selected from an alcohol, ketone or ether; and a homecare or personal care active ingredient. Homecare and personal care products comprising the gel composition are also disclosed.

Description

GEL COMPOSITIONS

Technical field

The present invention relates to gel compositions, in particular gel compositions for use in homecare and personal care applications.

Background

It is known to provide homecare and personal care products in a gel format which releases an active ingredient (e.g. perfume, detergent) over time, or upon exposure to mechanical or chemical stimuli. For example, it is known to provide a cleaning gel which sticks to the bowl of a toilet and gradually dissolves with each flush, thereby releasing a cleaning agent. It is also known to provide an air freshening gel, which sits within a housing (e.g. cage) and gradually releases a fragrance by evaporation.

To make such gels, it is common to create a suitable carrier composition by adding components to a compatible liquid medium (solvent), and then modifying the rheology of the carrier composition using a suitable thickening (gelling) agent. However, the gelling effect of the thickening agents can be sensitive to the components of the carrier composition, including the liquid medium and particular active ingredient(s). Conversely, the performance of the components in the carrier composition can be negatively impacted by the particular thickening agent used.

Ideally, the gel should be sufficiently mouldable and malleable to allow it to be formed into a desired shape during manufacture, but then sufficiently self-supporting and robust to retain the desired shape longer term. In particular, the mechanical and chemical properties must remain storage stable so as to allow the gel to be transported, stored, handled and subsequently used. For example, the gel must not display unwanted changes in mechanical properties (such as changes in strength, rigidity and friability) over time or with changes in temperature, humidity or other environmental conditions.

In view of this, the range of homecare and personal care products based on such gel compositions is relatively limited, and there remains a need to develop further gels with improved properties. Summary of the invention

In view of the above, it is an aim of the present invention to provide gel compositions which are suitable for delivering a range of active ingredients.

In particular, it is an aim of the present invention to provide gel compositions which can be readily formed into a desired product shape, and which are convenient for consumers to handle and use. To this end, the present inventors have sought to develop self-supporting gels which are sufficiently chemically and mechanically stable to be handled by consumers.

For convenience, it is also an aim of the present invention to provide such gels in the form of a unit dose, such as a tablet or bolus, to allow precise“controlled” delivery of a desired amount of active ingredient, and avoid waste and spillage.

At its most general, the present invention provides, in a first aspect, a gel composition suitable for making a homecare or personal care product, the gel composition comprising: a thickener selected from hydroxypropyl methylcellulose (HPMC) and gelatin;

a low boiling point non-aqueous liquid medium, selected from an alcohol, ketone or ether; and

a homecare of personal care active ingredient comprising one or more actives selected from a cleaning active, care active, cosmetic active, fragrance active, or a corrosive active.

Advantageously, the use of a low boiling point non-aqueous liquid medium selected from an alcohol, ketone or ether in a composition thickened with HPMC or gelatin allows the gel composition to initially have a malleable consistency which subsequently sets and hardens as the liquid medium evaporates. This allows the gel composition to initially be deformed into a desired shape, and then to harden into a stable form which can be stored long term. Thus, the gel composition of the first aspect provides a suitable starting material for processing into a final homecare or personal care product, which can provide great flexibility in terms of the form and content of the final product.

Thickener

The thickener may be hydroxypropyl methylcellulose (often referred to as hypromellose, and referred to herein as HPMC). The present inventors have found that HPMC forms gels with all of the non-aqueous liquid media specified above, and is relatively insensitive to the inclusion of the active ingredients. This means that the system can be adapted for use in a range of products, and allows the liquid medium to be chosen based on the particular active ingredients being used, without being particularly constrained by consideration of the compatibility of the thickener and liquid medium. Furthermore, the evaporation rate of liquid media from HPMC at atmospheric pressure is relatively rapid, meaning that an initial gel can be formed into a desired shape and rapidly solidify through evaporation of the liquid medium to produce a storage stable product. This has advantages for manufacturing, since the time between gel production and final packaging can be minimised. In addition, HPMC gels can be structurally robust and do not disintegrate or collapse upon drying.

The weight average molecular weight of the HPMC may be, for example, 10 kDa or more, 15 kDa or more, or 20 kDa or more. The upper limit for the weight average molecular weight of the HPMC may be, for example 200 kDa, 100 kDa, 75 kDa, or 50 kDa.

Alternatively, the thickener may be gelatin. Again, the present inventors have found that the evaporation rate of liquid media from gelatin at atmospheric pressure is relatively rapid, meaning that an initial gel can be formed into a desired shape and rapidly solidify through evaporation of the liquid medium to produce a storage stable product.

The thickener may be present in an amount of, for example, 0.01 wt.% or more; 0.1 wt.% or more; 0.5 wt.% or more; 1 wt.% or more; 1.5 wt.% or more; 2 wt.% or more; or 3 wt.% or more, the wt.% being relative to the weight of the composition as a whole. The upper limit for the amount of thickener may be, for example, 60 wt.%, 50 wt.%, 40 wt.%, 35 wt.%, 30 wt.%, 25 wt.%, 20 wt.%, 15 wt.%, 12 wt.%, 10 wt.%, 8 wt.%, 6 wt.%, 5 wt.%, or 4 wt.%. For example, the amount of thickener may be 0.01 to 25 wt.%, 0.5 to 10 wt.%, or 1 to 5 wt.%.

Liquid Medium

Preferably, the low boiling point non-aqueous liquid medium has an atmospheric boiling point (that is, a boiling point as measured at a pressure of 1 atmosphere) of less than 100°C, for example less than 95°C, less than 90°C, or less than 80°C. The atmospheric boiling point is the value determined for the pure liquid.

The non-aqueous liquid medium is selected from alcohols, ketones, and ethers. For example, the non-aqueous liquid medium may be selected from ethanol, isopropyl alcohol, acetone, or diethyl ether. Advantageously, these liquid media have relatively low atmospheric boiling points (that is, the boiling point of the pure liquid as measured at a pressure of 1 atmosphere), meaning that the evaporation rate of the liquid media is relatively rapid. In addition, it has been found that HPMC forms stable gels with all of these solvents, and that these gels can incorporate a wide range of homecare and personal care active ingredients.

Preferably, when the thickener is gelatin the low boiling point non-aqueous liquid medium is acetone.

The gel composition may comprise more than one type of non-aqueous liquid medium, as described above.

The non-aqueous liquid medium may be present in an amount of 5 wt.% or more, 10 wt.% or more, 15 wt.% or more, 20 wt.% or more, 25 wt.% or more, 30 wt.% or more, 40 wt.% or more, 50 wt.% or more, 60 wt.% or more, 70 wt.% or more, 75 wt.% or more, 80 wt.% or more, 85 wt.% or more, or 90 wt.% or more, as a percentage of the total weight of the gel composition.

In instances where the gel composition comprises more than one type of non-aqueous liquid medium, the total amount may be 5 wt.% or more, 10 wt.% or more, 15 wt.% or more, 20 wt.% or more, 25 wt.% or more, 30 wt.% or more, 40 wt.% or more, 50 wt.% or more, 60 wt.% or more, 70 wt.% or more, 75 wt.% or more, 80 wt.% or more, 85 wt.% or more, or 90 wt.% or more, as a percentage of the total weight of the gel composition.

The gel composition may also contain water, in addition to the non-aqueous liquid medium. The water content of the gel composition may be, for example, 80 wt.% or less, 70 wt.% or less, 60 wt.% or less, 50 wt.% or less, 40 wt.% or less, 30 wt.% or less, 25 wt.% or less, 20 wt.% or less, 15 wt.% or less, 10 wt.% or less, 5 wt.% or less, or 2 wt.% or less, as a percentage of the total weight of the gel composition.

Active ingredients

The gel composition comprises a homecare and/or personal care active ingredient. The active ingredient is a constituent which imparts a specific activity to the gel composition which makes the gel suited to a particular application. The active ingredient achieves an effect beyond formation of the gel itself, and may be deliverable from the gel to achieve that effect.

The homecare or personal care active ingredient may be one or more actives selected from a cleaning active, care active, cosmetic active, fragrance active, or a corrosive active.

The active ingredient may be a cleaning active, such as a surface cleaning active (e.g. hard surface cleaning active), a fabric cleaning active, a body cleaning active, or a make-up removal active.

The active ingredient may be a care active, such as a conditioning active (e.g. a fabric conditioning active), a softening active, a skincare active (e.g. moisturiser or sunscreen), a medical active, an anti-corrosion active, or a polish active.

The active ingredient may be a cosmetic active, such as a make-up colorant.

The active ingredient may be a fragrance active, such as a perfume.

The active ingredient may be a corrosive active, such as a paint stripper.

The active ingredient may be present in an amount of, for example, 50 wt.% or less, 40 wt.% or less, 30 wt.% or less, 20 wt.% or less, or 10 wt.% or less, as a percentage of the total weight of the gel composition.

Surfactant

Suitable cleaning actives include surfactants.

The surfactant may be present in an amount of 50 wt.% or less, 40 wt.% or less, 30 wt.% or less, 20 wt.% or less, or 10 wt.% or less, as a percentage of the total weight of the gel composition. The surfactant may be present in an amount of 0.001 wt.% or more, 0.01 wt.% or more, 0.05 wt.% or more, or 0.1 wt.% or more. Preferably, the surfactant is present in an amount of 0.01 to 10 wt.% of the composition. For the avoidance of doubt, the above ranges refer to the total amount of surfactant in the gel composition. The surfactant may be selected form the group consisting of anionic, non-ionic, cationic, amphoteric/zwitterionic surfactants and mixtures thereof.

Preferably, the surfactant is or includes a non-ionic surfactant, or mixture of non-ionic surfactants.

Nonionic surfactants include primary and secondary alcohol ethoxylates, especially C8-C20 aliphatic alcohol ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C10-C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated nonionic surfactants include alkyl polyglycosides, glycerol monoethers and polyhydroxy amides (glucamide). For example, the nonionic surfactant may be alcohol ethoxylate, nonylphenol ethoxylate, alkylpolyglycoside, alkyldimethylamineoxide, ethoxylated fatty acid monoethanolamide, fatty acid monoethanolamide, polyhydroxy alkyl fatty acid amide, or N-acyl N-alkyl derivatives of glucosamine (“glucamides”). Mixtures of nonionic surfactant may be used.

Nonionic surfactants that may preferably be used include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 35 moles of ethylene oxide per mole of alcohol, and more especially the C9-C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol.

Suitable anionic surfactants include alkyl sulphonates, such as alkylbenzene sulphonates, particularly linear alkylbenzene sulphonates having an alkyl chain length of Cs-C-is. The counter ion for anionic surfactants is generally an alkali metal, typically sodium, although other counter-ions for example MEA, TEA or ammonium can be used. Suitable linear alkyl benzene sulphonate surfactants include Detal LAS with an alkyl chain length of from 8 to 15, more preferably 12 to 14.

Other examples of suitable anionic surfactants include linear carbon chain sulfates, alcohol ether sulfates, alcohol sulfates, alkyl- and alkylaryl-alkyoxylated carboxylic acid, and the acid forms of these anionic surfactants. For example, the composition may comprise an alkyl polyethoxylate sulphate anionic surfactant of the formula: R0(C₂H₄0)_XS03-M⁺ where R is an alkyl chain having from 10 to 22 carbon atoms, saturated or unsaturated, M is a cation which makes the compound water-soluble, especially an alkali metal, ammonium or substituted ammonium cation (e.g. monoisopropanol ammonium), and x averages from 1 to 15. Preferably R is an alkyl chain having from 12 to 16 carbon atoms, M is sodium and x averages from 1 to 3, preferably x is 3; This is the anionic surfactant sodium lauryl ether sulphate (SLES). It is the sodium salt of lauryl ether sulphonic acid in which the

predominantly C12 lauryl alkyl group has been ethoxylated with an average of 3 moles of ethylene oxide per mole.

Suitable cationic surfactants include quaternary ammonium salts having the formula:

R^aR^bR^cR^dN⁺X- where R^a, R^b, R^c, and R^d are each Ci-₂₄ alkyl, aryl or aralkyl groups, and X is a suitable counterion such as F, Cl, Br, I or an alkyl sulfate.

Suitable zwitterionic surfactants include, for example, betaines, sultaines and glycines.

Viscosity

The gel composition may have a viscosity of 500 cP or more at 25°C. For example, the gel composition may have a viscosity of 1 ,000 cP or more; 1 ,500 cP or more; 2,000 cP or more; 3,000 cP or more; 4,000 cP or more; 5,000 cP or more; 10,000 cP or more; 20,000 cP or more; 30,000 cP or more; 40,000 cP or more; 50,000 cP or more; 75,000 cP or more; or 100,000 cP or more, as measured at 25°C. The upper limit for the viscosity may be, for example, 200,000 cP, 150,000 cP, 100,000 cP, 75,000 cP or 50,000 cP. The viscosity can be determined using a Stony Brook Portable Field Viscometer (PDVdi-120) according to the manufacturer’s instructions.

Weight loss on drying

As noted above, the gel composition of the first aspect is capable of losing non-aqueous liquid medium so as to change its viscosity over time. To aid manufacturing, this

evaporation rate may be relatively rapid so as to allow the composition to rapidly harden. The evaporation rate may be measured by the rate of weight loss upon drying. For example, the gel composition may lose 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 80% or more of its weight when heated at a temperature of 125°C for 5 minutes. This weight loss may be monitored using a Mettler Toledo Halogen Analyzer (HG53). More specifically, the weight loss may be monitored by pipetting a 300 mg sample of the gel composition onto the centre of the foil weighing boat used in the HG53 weight instrument, and heating at a temperature setpoint of 125°C for 5 minutes.

Optional combinations

The gel composition may comprise 1 wt.% or more of the thickener, 10 wt.% or more of the low boiling point non-aqueous liquid medium, and 20 wt.% or less of the active ingredient or mixture of active ingredients (e.g. one or more surfactants).

For example, the gel composition may comprise 2 wt.% or more of the thickener, 20 wt.% to 95 wt.% of the low boiling point non-aqueous liquid medium, 5 to 80 wt.% water, and 20 wt.% or less of the active ingredient or mixture of active ingredients (e.g. one or more surfactants).

Product forms

In a second aspect the present invention provides a homecare product manufactured or manufacturable using a gel composition according to the first aspect. Specifically, the present invention provides a homecare product incorporating a solid gel obtained or obtainable using a gel composition according to the first aspect. The solid gel is the result of forming the gel composition of the first aspect, and allowing the low melting point liquid to evaporate. The solid gel may be a soft gel which, for example, breaks up easily when disturbed. It may be a firm gel which, for example, can retain its shape during handling but can be broken up by application of greater force. In between, the gel may be elastic, but retain its shape better than a soft gel.

The gel composition may be present in the form of a ball or tablet. For example, the gel composition may be a ball of a surface cleaning composition which can be spread onto a cloth. ln a third aspect, the present invention provides a personal care product manufactured or manufacturable using a gel composition according to the first aspect. Specifically, the present invention provides a personal care product incorporating a solid gel obtained or obtainable using a gel composition according to the first aspect. The gel may have any of the features described above in relation to the homecare product.

Again, the gel composition may be present in the form of a ball or tablet. For example, the gel composition may be a tablet of cosmetic material which can be spread directly onto the skin.

In both the second and third aspects, the gel composition may be in the form of a unit dose, containing a pre-determined amount of said active ingredient.

The homecare or personal care product may provide the gel in the form of a unit dose provided on a substrate. For example, the product may comprise a gel composition film on a substrate. The film may have a thickness of, for example, 0.25 mm or more, 0.5 mm or more, 0.75 mm or more, 1 mm or more, 1.5 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 7.5 mm or more, 10 mm or more, or 20 mm or more.

As will be appreciated from the discussion above, the amount of the low boiling point non- aqueous liquid medium present in the gel compositions of the second and third aspects will be lower than that for the first aspect, due to evaporation of the liquid medium during manufacture.

Accordingly, in the gel composition of the second and third aspects, the amount of the low boiling point non-aqueous liquid medium may be, for example, 1 wt.% or less, 5 wt.% or less, 10 wt.% or less, 15 wt.% or less, 20 wt.% or less, 25 wt.% or less, 30 wt.% or less, 40 wt.% or less, or 50 wt.% or less, as a percentage of the weight of the gel composition as a whole.

The viscosity of the gel composition in the second and third aspects may be, for example, 5,000 cP or more; 10,000 cP or more; 15,000 cP or more; 20,000 cP or more; 30,000 cP or more; 40,000 cP or more; 50,000 cP or more; 75,000 cP or more; or 100,000 cP or more, as measured at 25°C using the instrument described above in relation to the first aspect. In a fourth aspect, the present invention provides use of a gel composition according to the first aspect in the manufacture of a homecare or personal care product.

In a fifth aspect, the present invention provides a method of provides a method of forming a homecare or personal care product according to the third aspect, comprising forming a gel composition according to the first aspect and allowing the gel composition to dry.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a plot showing the mass change over time of HPMC gel compositions according to the first aspect of the invention with different types and quantities of non-aqueous liquid medium.

Figure 2 is a plot showing the viscosity of HPMC gel compositions formed using IPA or ethylene glycol as the non-aqueous liquid medium, and incorporating different active ingredients.

EXAMPLES

Experiments were carried out to demonstrate the advantageous characteristics of the gel compositions of the present invention.

In a first set of experiments, the solidification rate of HPMC gel samples containing different solvents was assessed. These results showed that gels formed with low boiling point non- aqueous solvents solidified more rapidly than those with higher boiling point water or ethylene glycol.

Table 1 - Drying Rate

remaining 50 wt.% corresponds to water Next, the solidification rate was quantitatively assessed by monitoring the mass change of gels over time due to solvent evaporation. More specifically, 295 ± 70 mg samples of gels having the compositions shown below were taken and allowed to dry for 5 minutes at a temperature of 125°C with the mass monitored using a halogen moisture analysis machine (Mettler Toledo Halogen Moisture Analyser HG53).

Table 2 - Drying Rate Experiments

^* As a percentage of the starting composition

As can be seen in Figure 1 , gels with higher ratios of the low boiling point acetone and diethyl ether dried significantly faster than those with lower ratios. For example, the data show that a gel formed with 88.8 wt.% acetone and 9 wt.% water reached a relatively stable mass after around 3.5 minutes, indicating that the gel had almost completely solidified during that time.

Next, the compatibility of the gel system with different active ingredients was assessed. A series of HPMC gels were created with different solvents containing various active ingredients, as shown in Table 3 below.

Table 3 - HPMC gels

^* as a percentage of the starting composition

^(a) Palmera A9212; ^(b) Polyquart PRO A; ^(c) Barquat MS-100; ^(d) Marlinat 242/90M; ^(e) Neodol 45-6.8; <^f) Neodol 91 -5.

These results show that, for the relatively low boiling point compounds acetone and I PA, stable gels were formed with all active ingredients (as indicated by the Ύ” in the table above).

In contrast, for ethylene glycol, the majority of active ingredients prevented stable gel formation and produced unwanted side effects, such as foaming (for active ingredients (d)- (f)) and precipitate formation (for active ingredient (a)). A stable gel was formed using ethylene glycol and the anionic surfactant Marlinat 242/90M, but it was found that the drying rate of the gel was significantly slower than for gels formed with acetone and I PA (-480 pg s 1 for ethylene glycol, compared to -1060 pg s ¹ and -1370 pg s ¹ for acetone and I PA respectively, as measured over a period of two minutes using the halogen moisture analyser discussed above).

Next, the viscosity of IPA and ethylene glycol formulations with the different active ingredients above was measured using a Stony Brook field viscometer (PDV di-120 - operated according to the manufacturer’s instructions). The results, shown in Figure 2, demonstrate that the IPA formulations had a significantly higher viscosity compared to the ethylene glycol formulations (note that the viscosity of control and Palmera ethylene glycol formulations was not measured).

Thus, these results show that HPMC-based gel compositions according to the present invention, incorporating a low boiling point non-aqueous liquid medium, are able to form stable gel compositions with a range of active ingredients, and dry to form stable gels over a relatively short period.

The experiments were repeated using gelatin as the thickener. The gelatin formed a stable gel with acetone in the absence of active ingredients, but did not form suitable gels when any of the active ingredients listed in Table 3 were present in the solvent.

Claims

CLAIMS:

1. A gel composition suitable for making a homecare or personal care product, the gel composition comprising:

a thickener selected from hydroxypropyl methylcellulose (HPMC) and gelatin;

a homecare or personal care active ingredient comprising one or more actives selected from a cleaning active, care active, cosmetic active, fragrance active, or a corrosive active

2. A gel composition according to claim 1 , wherein the thickener is hydroxypropyl methylcellulose.

3. A gel composition according to claim 1 , wherein the thickener is gelatin.

4. A gel composition according to any one of claims 1 to 3, wherein the low boiling point non-aqueous liquid medium is acetone.

5. A gel composition according to any one of claims 1 to 3, wherein the low boiling point non-aqueous liquid medium is diethyl ether.

6. A gel composition according to any one of claims 1 to 3, wherein the low boiling point non-aqueous liquid medium is ethanol.

7. A gel composition according to any one of claims 1 to 3, wherein the low boiling point non-aqueous liquid medium is isopropyl alcohol.

8. A gel composition according to any one of the preceding claims, wherein the low boiling point non-aqueous liquid medium is present in an amount of 5 wt.% or more.

9. A gel composition according to any one of the preceding claims, further comprising water in an amount of 80 wt.% or less.

10. A gel composition according to any one of the preceding claims, wherein the thickener is present in an amount of 2 wt.% or more.

1 1. A gel composition according to any one of the preceding claims, wherein the viscosity is at least 1 ,000 cP at a temperature of 25°C.

12. A gel composition according to claim 11 , comprising 1 wt.% or more of the thickener, 10 wt.% or more of the low boiling point non-aqueous liquid medium, and 20 wt.% or less of the active ingredient.

13. A homecare product manufactured using a gel composition according to any one of claims 1 to 12.

14. A personal care product manufactured using a gel composition according to any one of claims 1 to 12.

15. Use of a gel composition according to any one of claims 1 to 12 in the manufacture of a homecare or personal care product.