WO2020035369A1

WO2020035369A1 - Homecare and personal care articles with multilayer structure

Info

Publication number: WO2020035369A1
Application number: PCT/EP2019/071237
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; WO2020035376A1; WO2020035377A1

Abstract

The present invention is concerned with articles for use in homecare or personal care applications, comprising a multilayer structure on a substrate, the multilayer structure comprising one or more active ingredients, wherein there are variations in the mechanical, structural or chemical properties of the layers across the multilayer structure. The invention also relates to multilayer articles for use in homecare or personal care applications, comprising at least 4 layers having one or more active ingredients dispersed therein, wherein there are variations in the mechanical, structural and/or chemical properties of the layers across the multilayer structure. Methods of making and using such articles are also discussed.

Description

HOMECARE AND PERSONAL CARE ARTICLES WITH MULTILAYER

STRUCTURE

Technical field

The present invention relates to homecare and personal care articles.

Background

A number of homecare and personal care products are sold in solid powder or gel forms including, for example, water-soluble dishwasher and laundry tablets, toilet rim blocks, air-freshener blocks, or skin care gels.

For ease of design and manufacture, such products are typically provided as a single bulk composition. To allow the production of such product forms, a range of auxiliary ingredients are typically present alongside active ingredients, which adapt the chemical and physical properties of the solid. For example, in the case of water-soluble tablets, it may be necessary to include a disintegrant in order to achieve a suitable rate of dissolution or dispersion. In other instances, physical properties may need to be tailored through careful choice of binder or thickener.

In certain instances, the provision of a single bulk composition is undesirable, due to the occurrence of unwanted interactions between ingredients or the need to provide different ingredients at different times to achieve multistep treatments. In view of this, it is known to provide solids having layers containing different ingredients, which optionally release their active ingredients at different times. For example, it is known to provide two-layer dishwasher tablets having different active ingredients in each layer, formed through compressing a two-layer mixture of powders together. However, again, in such instances, the overall properties of the tablet are essentially dictated by the properties of the bulk composition, and the need to form the tablet through compression. Thus, it is necessary to include auxiliary ingredients in order to tailor the properties so that the product is suitable for manufacture, handling and subsequent use.

It would be useful to develop new and improved solid homecare and personal care products which are convenient for consumers to use. Summary of the invention

In view of the above, it is an aim of the present invention to provide homecare and personal care products with improved physical and/or chemical properties. It is also an aim of the invention to provide solid homecare and personal care products which can be used in different ways to conventional products.

To this end, in a first aspect, the present invention provides an article for use in homecare or personal care applications, comprising a multilayer structure on a substrate, the multilayer structure comprising one or more active ingredients, wherein there are variations in the mechanical, structural or chemical properties of the layers across the multilayer structure.

Suitably, the multilayer structure takes the form of a stack of layers. The variations in properties must occur across the multilayer structure, and may optionally occur along the multilayer structure. The variations in properties across the multilayer may be due to differences between intra- and inter-layer bonding, or due to the relative properties of the different layers.

Advantageously, articles of the present invention provide an easy to handle product form which can achieve improved delivery characteristics for active ingredients due to variations across the layers.

The substrate provides a surface for building up the multilayer structure layer-by-layer, without requiring compression of the layers. This is in contrast to conventional pressed powder tablets, where the final compression step involves the application of high pressure to the entire multilayer structure, and hence restricts the choice of layer materials to those able to tolerate high pressures.

The substrate also allows the articles to be used in situations where the stack of layers is too small or delicate for a consumer to handle directly, and/or where the stack of layers contains ingredients which a consumer should not contact directly, such as corrosive chemicals or staining dyes.

Furthermore, the substrate can act to protect at least part of the multilayer (e.g. from contact with water) and/or reinforce the multilayer. In particular, the substrate may reinforce the multilayer structure so as to reduce the effect of mechanical stresses and strains which would otherwise break an equivalent unsupported multilayer structure apart. This also allows greater flexibility in the choice and dimensions of layer materials compared to those used in compressed tablets, and can reduce the need to use auxiliary ingredients to tailor the physical properties of the matrix.

The above advantages mean that the articles are particularly well suited to applications in which the article is intended to be rubbed against a surface to deliver its active

ingredients, since the substrate improves ease of handling. In particular, the substrate can be designed specifically to allow easy delivery of the active ingredients to the surface, without having to factor in additional considerations which would arise if the substrate itself were intended to disintegrate to deliver active ingredients. This is in contrast to known two-layer dishwasher tablets, where the tablet is formed through compression of powder, and is not intended for, nor suitable for, being applied directly to surfaces to achieve its effects.

The multilayer structure has variations in the mechanical, structural and/or chemical properties across layers. As noted above, these variations arise due to differences in the material of one layer and either the interface with another layer or the material of another layer perse. These variations occur across the stacked multilayer structure, i.e. in a direction transverse to the interface between layers. For example, when the multilayer structure is formed from flat planar layers, the variations occur in a direction transverse to the plane of the layers.

The layers generally comprise a matrix having the one or more active ingredients distributed/dispersed therein. The matrix may serve as a carrier material for the active ingredient(s).

The matrix is a solid. Suitable matrix materials for forming the matrix include gels, waxes, soaps, plastics and powders, including sintered powders and powders held together by a binder. Optionally, the matrix is a non-compressed matrix, e.g. not a compressed powder.

Optionally, the variations in mechanical, structural and/or chemical properties may arise due to differences in the properties of the matrix material in different layers. In particular, the plurality of layers may comprise at least one layer of a first matrix material in contact with (e.g. directly bonded to) at least one layer of a second matrix material, wherein the first and second matrix materials have different mechanical, structural and/or chemical properties. The first and second matrix material can be arranged in any order relative to the substrate (i.e.“first” does not indicate closer proximity to the substrate).

Advantageously, providing multiple layers of matrix materials with different properties provides a versatile means of adjusting mechanical, structural and/or chemical properties of the multilayer structure so that they are different to a single-layer of equivalent overall dimensions formed from the same ingredients.

Optionally, the plurality of layers may comprise alternating layers of the first and second matrix materials. Such an arrangement can have significantly different properties to materials including the two materials as two thick connected layers, as is known in dishwasher tablets.

The first and second matrix materials are solids. Optionally, both the first and second matrix materials are a gel.

The first and second matrix materials may have different structural properties.

For example, the first matrix material may be relatively more porous than the second matrix material. In other words, the proportion of the material occupied by voids may be relatively higher in the first matrix material than in the second matrix material. For example, the difference in porosity between the first and second matrix materials may be at least 5%; at least 10%; at least 15%; at least 20%; at least 25%; at least 30%; at least 40% or at least 50% (the percentage corresponding to the difference in the fraction of the volume of voids in the matrix materials). The porosity may be calculated using conventional methods appropriate to the particular material. For example, for randomly arranged pores, the porosity may be calculated by optically determining the area of the pores visible in a cross-section of the material under a microscope, and converting this to a percentage of the area of the material as a whole.

This difference in porosity may mean that the first matrix material preferentially absorbs liquid when immersed. For example, the article may comprise water-soluble first and second matrix materials, wherein immersion in water causes the more porous first matrix material to absorb water and dissolve first, thereby releasing the second matrix material to dissolve more slowly.

The difference in porosity may also mean that ingredients dispersed within the matrix are released from the different layers at different rates. For example, active ingredients in the first matrix material may be released faster than those in the second matrix material.

Alternatively or additionally, the first matrix material and second matrix material may be porous, and the average (mean) size of pores in the first matrix may be smaller than those in the second matrix material. In this way, the differences between the pore characteristics can be used to achieve different wicking behaviour in the product. For example, the first and second matrix materials may be made from the same water-soluble composition, but with different pore sizes, whereby the material with smaller pores rapidly wicks water into its structure, whereas the material with larger pores wicks water more slowly and hence dissolves more slowly. Differences in pore size can also be used to preferentially direct liquid through the article. For example, having liquid wick through multiple thin layers of porous material may lead to quicker transfer of liquid across the article than for an equivalent overall thickness of the bulk material. For randomly arranged pores, the pore size may be calculated by optically determining the area of the pores visible through a cross-section of the matrix material under a microscope, and calculating the mean value.

Alternatively or additionally, the first matrix material may be relatively denser than the second matrix material. The density of the matrix material may be used to change other properties of the matrix, such as solubility, viscosity, porosity and pore size. Furthermore, when the first matrix material is water soluble, changes in density can be used to alter the dissolution characteristics of the article. For example, the article may sink when first added to water due to the presence of a dense water-soluble layer of first matrix material, and gradually float as the first matrix material dissolves, which can be used to control the position of the article in solution over time.

The first and second matrix materials may have different mechanical properties. For example, the first matrix material may be relatively harder than the second matrix material. This may allow, for example, preferential disintegration of the second matrix material before the first matrix material upon application of a mechanical force. For example, a user pressing down on the stacked multilayer structure may cause

disintegration of the second matrix material, thereby delaminating the structure to allow easier distribution of the first matrix material.

The first matrix material may have different rheological properties to the second matrix material. For example, when the first and second matrix materials are gels, the first matrix material may have a relatively lower viscosity than the second matrix material.

This can be used to enhance the spreadability of the composition, which is useful when the homecare or personal care article is intended to be spread on a surface. In such instances, the first matrix material may be a gel which is easily spread onto a surface, and the second matrix material may be a harder abradable gel which slowly wears away as it is rubbed against a surface. This structure provides a means of spreading the harder abradable gel across a surface. The relevant viscosities may be determined at typical temperatures at which the article is used, e.g. 20°C; 25°C, 30°C, or 37°C.The difference between the viscosity of the first and second matrix materials may be, for example, at least 1 ,000 cP; at least 2,000 cP; at least 3,000 cP; at least 4,000 cP; at least 5,000 cP; at least 10,000 cP; at least 25,000 cP or at least 50,000 cP.

Additionally or alternatively, the first and second matrix materials may have different chemical properties. For example, the first matrix material may be relatively more soluble than the second matrix material, e.g. more water soluble at a temperature of 20°C, 30°C, 37°C, 40°C, or 50°C. Advantageously, this behaviour can be used to control the dissolution behaviour of active ingredients from the article.

Optionally, the different mechanical, structural and/or chemical properties are achieved by using different types of matrix materials for the first and second matrix materials, and/or by using different conditions during formation of the first and second matrix materials (e.g. different temperatures).

Optionally, when the first and second matrix materials are thickened gels, the different mechanical, structural and/or chemical properties can be achieved by using a different amount or type of thickener to form the first matrix material compared to the second matrix material.

Optionally, the different mechanical, structural and/or chemical properties are achieved by using first and second matrix materials with different degrees of crystallinity. This may be achieved, for example, by using different temperature profiles during the formation of the layers of first and second matrix material, e.g. heating to a different temperature before cooling and/or cooling at a different rate.

In addition or alternatively to variations between the matrix material forming the bulk of each layer, the variation in mechanical, structural and/or chemical properties may be due to the bonding between layers (interlayer bonding) being different compared to the bonding within layers (intralayer bonding). For example, the bonding between layers may be relatively weaker than the bonding within layers. This may arise as a result of differences in bond types (e.g. covalent bonding vs. non-covalent bonding) or bond density. Alternatively, the bonding between layers may have a different chemical behaviour compared to the bonding within layers - e.g. the bonds between layers may be more water soluble than those within layers. This can lead to rapid delamination of the multilayer structure, which can be used to achieve enhanced delivery.

For example, when the layers are water-soluble, the bonding between layers may be broken down faster than the bonding within layers when the article is immersed in water (e.g. due to relatively fewer bonds, or different bonds). Advantageously, the presence of weaker water-soluble bonds between layers leads to rapid delamination of the structure upon contact with water, which leads to a rapid increase in the surface area of the material. This can help to improve the rate of dissolution compared to the provision of the water-soluble material as a single block of material, and thus can reduce the need for the incorporation of disintegrants in the formulation.

Furthermore, in instances where it is desirable to spread a relatively hard or friable product across a surface, initial delamination can allow the product to be easily distributed in a way which would not be possible for a single block of material, or only possible with the addition of auxiliary ingredients. Delamination into separate layers may also make it easier to break apart individual layers once the product has been spread. The relatively weaker interlayer bonding may be achieved by building up the structure layer-by-layer, since this can affect the relative strength of the interlayer and intralayer bonding. For example, when the matrix materials are gels, the process may involve forming a gel layer and allowing it to solidify before application of a subsequent gel layer.

Laver structure

Optionally, the multilayer structure comprises only 2 layers on the substrate.

Alternatively, the article may comprise at least 3 layers, at least 4 layers, at least 5 layers, at least 6 layers, at least 7 layers, at least 8 layers, at least 9 layers, at least 10 layers, at least 15 layers, at least 20 layers, at least 25 layers, at least 30 layers, at least 40 layers, or at least 50 layers. The upper limit for the number of layers is not particularly limited, but may be, for example, 100 layers, 50 layers, 40 layers, 30 layers or 20 layers. In articles comprising more than two layers, the layers may comprise only the first and second matrix materials, or may optionally comprise further matrix materials.

The properties of articles of the present invention can change significantly as the number of layers is increased. In particular, the behaviour of a stack containing a relatively large number of layers can be very different to those of a stack of equivalent overall dimensions containing relatively fewer layers. The overall storage stability of the different stacks may be similar, but when in use the properties of the individual thin layers may allow enhanced delivery. In particular, the individual layers may be more liable to disintegrate through application of mechanical force (e.g. more prone to snap or crumble so as to release active ingredients than a bulk composition, or prone to delaminate in a way not possible with a bulk composition) and/or exposure to chemicals (e.g. the relatively thin layers will have a higher surface area to volume ratio than a large bulk composition, which can lead to faster dispersion and dissolution) as the number of layers is increased. The structure may also be more prone to delamination. This can allow enhanced delivery

characteristics without having to rely on the inclusion of large quantities of auxiliary ingredients, such as disintegrants.

This is in contrast to multilayer dishwasher tablets, where the number of layers is chosen to separate ingredients or allow sequential delivery, instead of being used specifically to adjust mechanical and/or chemical properties so as to speed up delivery of components. Indeed, in the present invention, each of the layers may have the same composition and be intended to be delivered at the same time, in contrast to known two-layer dishwasher tablets.

In articles comprising more than 2 layers, the layers may be arranged in a predetermined sequence, e.g. a regularly repeating sequence. For example, the first and second matrix materials may be arranged in a predetermined sequence, e.g. the first and second matrix materials may alternate (ABAB), or be arranged according to some other pattern (e.g. ABBA, AABB, ABCABC).

Advantageously, building up a structure from more than 2 layers according to a predetermined sequence of matrix materials can produce very different properties compared to a structure of equivalent size having only one layer of each matrix material. For example, in situations where the first matrix material dissolves rapidly in water and the second matrix material dissolves relatively more slowly, creating alternating layers of the first and second materials can lead to faster dissolution of the article as a whole compared to having only one layer of each material. In particular, when exposed to water, the first matrix material“gluing” the second matrix material layers together rapidly dissolves, which exposes a large surface area of the second matrix material to water, thus leading to faster dissolution than having a single layer of the second matrix material. In addition, when the article is intended to be spread across a surface, providing multiple alternating layers of first and second matrix material having different viscosities (e.g. a hard abradable gel and a softer spreadable gel) allows easier spreading of the article compared to an equivalent-sized two-layer structure having a single thick bulk

composition of first matrix material attached to a single thick bulk composition of the second matrix material.

Preferably the layers are relatively thin. Advantageously, thin layers can have different properties to those of relatively thicker layers, e.g. greater propensity to disperse, dissolve (e.g. due to higher surface area to volume ratio) or snap. For example, the individual layers may have a thickness which corresponds to less than 40%, less than 30%, less than 20%, less than 10% or less than 5% of the overall thickness of said multilayer structure.

Furthermore, the provision of the multilayer structure on a substrate allows the absolute thickness of the multilayer structure to be relatively small. In particular, the reinforcement provided by the substrate allows the formation of thin, high surface area multilayer structures which would be insufficiently mechanically robust to exist in a free-standing form. Advantageously, the high surface area of the multilayer structure can be used to achieve fast delivery of the components during treatment, e.g. fast dissolution

characteristics and/or quick transfer of the components when rubbed against a surface

Thus, the present invention also covers articles in which the overall thickness of the multilayer structure is relatively small, and is small compared to the multilayer’s lateral dimensions. For example, the overall thickness of the multilayer structure may be 10 mm or less; 5 mm or less; 4 mm or less; 3 mm or less; or 2 mm or less. The aspect ratio (the ratio of the longest lateral dimension of the multilayer structure to its thickness) may be at least 2:1 ; at least 3:1 ; at least 4:1 ; at least 5:1 ; at least 7:1 ; at least 10:1 ; at least 15:1 ; or at least 20:1.

The majority (e.g. at least 50%, at least 60%, at least 70%, at least 80%, at least 90%) or all of the layers may have a thickness of 3000 pm or less, 2500 pm or less, 2000 pm or less, 1000 pm or less, or 500 pm or less. The“thickness” of a layer may be determined by measuring the thickness of the layer under suitable magnification at at least five different positions, equally spaced along the length and/or width of the layer, and calculating the mean value.

Preferably, the article comprises at least 4 layers, at least 5 layers, at least 10 layers, at least 15 layers, or at least 20 layers each having a thickness of 3000 pm or less, 2000 pm or less, 1000 pm or less, or 500 pm or less. Advantageously, in such situations, the differences in the structural, mechanical and/or chemical properties can result in significantly different properties to an analogous single-layer composition of equivalent overall size.

The layers may be lines of matrix material, arranged so as to create a stacked line structure. Alternatively, the layers may be sheets of material e.g. planar sheets, arranged so as to create a stacked sheet structure. Advantageously, such structures may allow easy delamination of the stacked structure, compared to structures where individual layers are built up in a layered sphere type arrangement. For the sake of convenience, the article has dimensions which allow a user to handle the product. For example, the article may have a length (corresponding to the longest lateral dimension) of at least 0.5 cm, at least 1 cm, at least 2 cm, at least 3 cm, or at least 5 cm. The surface area of the article may be at least 1 cm², at least 2 cm², at least 3 cm², at least 4 cm², at least 5 cm², at least 10 cm²; at least 15 cm²; at least 20 cm²; at least 30 cm²; at least 40 cm²; or at least 50 cm². The volume of the article may be, for example, at least 5 cm³, at least 6 cm³, at least 7 cm³, at least 8 cm³, at least 9 cm³, at least 10 cm³, at least 20 cm³, at least 30 cm³, at least 40 cm³ or at least 50 cm³.

As mentioned above, the reinforcement provided by the substrate allows the formation of relatively thin multilayer structures having a high aspect ratio (length:thickness) which would be insufficiently mechanically robust to exist in a free-standing form. Thus, advantageously, the articles of the present invention may have an overall thickness of 10 mm or less, 7 mm or less, 5 mm or less, 4 mm or less, 3 mm or less or 2 mm or less. Additionally or alternatively, the ratio of the lengthdhickness of the article may be at least 3:1 ; at least 4:1 ; at least 5:1 ; at least 7:1 ; at least 10:1 ; at least 15:1 ; or at least 20:1 .

Release of active ingredients

Suitably, the article is capable of releasing the active ingredients upon application of a suitable stimulus, such as a mechanical force or a chemical (e.g. water) or environmental stimulus (e.g. temperature or humidity).

For example, the layers may be“erodible”, in the sense that the structure breaks down upon application of a stimulus, such as a mechanical force or a chemical (e.g. water) or environmental stimulus (e.g. temperature or humidity).

For example, the layers may be spreadable, abradable (worn down by rubbing or scraping), or friable (capable of crumbling upon application of a mechanical force).

Alternatively or additionally, the layers may be soluble (e.g. in water or in an organic liquid), swellable (e.g. in water), or porous (e.g. such that the active ingredient can be dissolved out of the matrix material). Gel matrix materials

The matrix material(s) used to form the layers may be a gel. For example, the matrix material may be a gel comprising at least 15 wt.% of a polyamide-based thickener, as described in our co-pending application EP 16174137.6.

The present applicants have found that compositions incorporating polyamide-based thickeners at levels of at least 15 wt.% can form solid, dry self-supporting gels.

Advantageously, the formation of these solid, dry gels is relatively insensitive to the nature of the active ingredient and other components in the composition, and can tolerate, for example, both non-ionic and cationic surfactants as active ingredients. In addition to versatility in the range of ingredients which can be tolerated, gel formation can also occur over a broad pH range.

The upper limit for the amount of such polyamide-based thickener may be, for example, 60 wt.%, 50 wt.%, 40 wt.%, 35 wt.%, 30 wt.% or 25 wt.%. Preferably, the polyamide- based thickener may be incorporated in the composition at a level of 15 to 25 wt.%. For example, the polyamide-based thickener may be incorporated into the composition at between 16 to 24 wt.%, 17 to 23 wt.%, 18 to 22 wt.%, or 19 to 21 wt.%. Advantageously, the applicants have found that thickener incorporated in an amount of 20 wt.% leads to formation of gels which show particularly good mechanical properties. In particular, the gels may be solid and dry.

The polyamide-based thickener may be an end-capped polyamide, such as a

polyaklyleneoxy-terminated polyamide thickener.

The polyalkyleneoxy-terminated polyamide thickener may comprise or consist of a block copolymer of the formula hydrocarbon-polyalkyleneoxy-polyamide- polyalkyleneoxy- hydrocarbon. The“polyalkyleneoxy” group is a polyether group based on repeated alkyleneoxy units, such as -CH2CH2O-, -CH₂CH₂(CH₃)0-. The block copolymer may have the following formula:

wherein, independently at each occurrence, R¹ is selected from C1-22 hydrocarbon radicals; R² is selected from C2-6 alkylene diradicals; R³ is selected from C2-52

hydrocarbon diradicals (preferably where at least 50 mol% of the R³ radicals have at least 34 carbons); R⁴ is selected from C2-36 hydrocarbon diradicals and C4-100 polyether diradicals; Z is selected from O and NH; x is an integer from 2 to 100; y is an integer from 1 to 10; and z is an integer from 2 to 100.

The term“hydrocarbon group” is intended to refer to groups containing only carbon and hydrogen atoms. Suitable hydrocarbon groups are formed from one or more of aliphatic and aromatic moieties. Suitable aliphatic moieties are alkyl, alkylene, alkenyl, alkenylene, alkynyl, alkynylene, cylocalkyl, cycloalkylene, cycloalkenyl, cycloalkenylene, cycloalkynyl, and cycloalkynylene moieties. Exemplary alkyl moieties are methyl, ethyl, propyl, hexyl, and 2-ethylhexyl; while exemplary alkylene groups are monoradials such as methylidene (=CH₂) and diradicals such as methylene (-CH2-), and ethylene (-CH2CH2-). Suitable aromatic moieties include, for example, phenyl, and naphthyl, and combinations thereof such as biphenyl. The hydrocarbon groups may be a combination of aromatic and aliphatic groups, such as benzyl, tolyl or xylyl.

The R¹ groups may be alkyl, such as C1-12 alkyl, in particular C1-4 alkyl. Optionally, each R¹ group is methyl.

The R² groups are C2-6 alkylene, in particular C2-4 alkylene. Optionally, each R² group is - CH2CH(R^2a)- wherein R^2a is selected from hydrogen, methyl and ethyl.

The R³ groups may have at least 30 carbons, such as 30-42 carbons. Preferably, at least 50 mol% of the R³ groups are C34 groups. For example, C34 groups may constitute at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol% or at least 95 mol% of the R³ groups. The R⁴ groups may be hydrocarbon groups having, for example, 1-20 carbons, in particular 1-10 carbons. For example, the R⁴ groups may be C1-20 alkylene groups, C_MO alkylene groups, or C2-6 alkylene groups. Optionally, at least 50% of the R⁴ groups have 2 carbons. Preferably, the R⁴ groups are ethylene groups (-CH2CH2-).

Alternatively, the R⁴ groups may be polyether groups, i.e. groups having blocks containing the repeating formula -O-R²-, where R² is as defined above.

Optionally, the block copolymer may have R¹ selected from C1-12 alkyl; R² selected from C2-6 alkylene, R³ selected from C30-42 hydrocarbon groups where at least 50 mol% are C34 groups; and R⁴ selected from C1-20 alkylene groups.

Optionally, the block copolymer may have R¹ selected from C1-4 alkyl; R² selected from -CH2CH (R^2a)- where R^2a is hydrogen, methyl or ethyl; R³ selected from C30-42 hydrocarbon groups where at least 50 mol% are C34 groups; and R⁴ groups which are -CH2CH2-.

The above block copolymers may be made by reacting together reactants comprising dimer acid, diamine, and a polyether having both hydrocarbon termination and

termination selected from amine, hydroxyl and carboxyl, according to the methods discussed in WO 02/059181.

The polyamide-based thickener may have a weight average molecular weight (M_w) of greater than 10,000, greater than 12,000, greater than 15,000; greater than 17,000, greater than 18,000, or greater than 18,500. The upper limit for the weight average molecular weight may be, for example, 25,000; 24,000; 23,000; 22,000; 21 ,000 or 20,000. For example, the weight average molecular weight may be 15,000 to 25,000; 17,000 to 23,000; 18,000 to 22,000; 18,000 to 21 ,000; or 18,000 to 20,000; or 18,500 to 20,000. Weight average molecular weights within these ranges are preferred, since the resulting gels are found to be dry and have good mechanical properties with comparatively low sensitivity to the other components and pH of the gel.

A particularly good balance of properties is observed for polyalkyleneoxy-terminated polyamide polymers having a M_w of -19,000, and hence ranges of 17,000 to 23,000; 18,000 to 22,000 and, in particular 18,500 to 20,000 are preferred. In particular, polymers having this range of molecular weights produced solid gels which displayed particularly good dryness, making them suitable for attaching to surfaces. These advantageous properties allow the gel compositions formed from polymers having this molecular weight range to be used in a variety of practical applications.

The weight average molecular weight is measured by preparing a solution of the copolymer or composition in a suitable solvent, e. g., tetrahydrofuran (THF) and identifying the retention time of the copolymer by gel permeation chromatography, and comparing that retention time to the retention times of solutions of polystyrene having known molecular weight characterizations.

The polyamide-based thickener may have a softening point of 50°C to 150°C, preferably 75°C to 125°C, more preferably 80°C to 100°C, most preferably 90°C to 100°C. The softening point may be determined by a Ring and Ball method, such as ISO 4625.

The polyamide-based thickener may have an acid number of less than 25, less than 20, preferably less than 15, more preferably less than 10. The skilled reader understands that the acid number corresponds to the mass of potassium hydroxide in milligrams required to neutralise one gram of the polyamide-based thickener. In instances where the polyamide-based thickener comprises a polyalkylkeneoxy-terminated polyamide copolymer of the form hydrocarbon-polyether-polyamide-polyether-hydrocarbon, the copolymer does not have any free carboxylic acid groups, and accordingly has an acid number of zero. However, when prepared from diacid, diamine and hydrocarbon- terminated polyether, some of the diacid may not react with the diamine and/or polyether, and accordingly the final product may have some unreacted carboxylic acid that will be responsible for the final product having an acid number greater than zero. Preferably, the product has a minor amount of this unreacted diacid, and thus only a small acid number. Esterification catalysts may be used to encourage all of the diacid to react with hydroxyl groups, so as to minimise the amount of free acid.

The polyamide-based thickener may have an amine number of less than 25, less than 20, less than 15, less than 10, less than 5, less than 3, less than 2 or less than 1. The skilled reader understands that the amine number is determined by titration of amine acetate from the polyamide thickener by a dilute, typically 1 N, HCI solution, and is calculated according to (A x N x 56.1 )/g sample, where A is ml. of HCI titrant consumed, N is the normality of HCI titrant and g is the sample weight in grams. In instances where the polyamide-based thickener comprises a polyalkylkeneoxy-terminated polyamide copolymer of the form hydrocarbon-polyether-polyamide-polyether-hydrocarbon, the copolymer does not have any free amine groups, and accordingly has an acid number of zero. However, when prepared from diacid, diamine and hydrocarbon-terminated polyether, some of the diamine may not react with the diacid and/or polyether, and accordingly the final product may have some unreacted amine groups that will be responsible for the final product having an amine number greater than zero. Preferably, the product has a minor amount of this unreacted diamine, and thus only a small amine number. Amidification catalysts may be used to encourage all of the diamine to react with carboxyl groups, so as to minimise the amount of free amine.

Optionally, the polyamide-based thickener is a polyalkyleneoxy-terminated polyamide thickener having a weight average molecular weight of 15,000 to 25,000, and a softening point of 75°C to 125°C. Preferably, the polyamide-based thickener is a polyalkyleneoxy- terminated polyamide thickener having a weight average molecular weight of 18,500 to 20,000, and a softening point of 80°C to 100°C. Thickeners having these properties were found to produce gels with particularly good properties with comparatively low sensitivity to the other components and pH of the gel. A particularly preferred polyalkyleneoxy- terminated polyamide thickener is Crystasense HP5, marketed by Croda.

Advantageously, polyalkyleneoxy-terminated polyamide thickeners, such as Crystasense HP5, may be water soluble.

The skilled reader is familiar with methods for depositing the gels, and other matrix materials. For example, the gels can be spread or dropped onto a surface, and allowed to set on the substrate.

Substrate

The multiple layers are provided on a substrate. As explained above, this provides a number of advantages over traditional compressed tablet multilayer tablets.

Optionally, the substrate is an applicator - a part which is suitable for consumers to handle so as to allow application of the multilayer structure to a surface. The substrate may be in the form of a sheet material, such as a sheet or film. For example, the substrate may take the form of a sheet material having a length

(corresponding to the longest lateral dimension) of at least 0.5 cm, at least 1 cm, at least 2 cm, at least 3 cm, or at least 5 cm. The average thickness of the sheet material is not particularly limited but may be, for example, at least 100 pm, at least 200 pm, at least 300 pm, at least 400 pm, at least 500 pm, at least 750 pm, or at least 1000 pm (as measured, for example, by determining the mean thickness based on the thickness at five equally spaced points along the length of the sheet material). The surface area of the substrate may be at least 1 cm², at least 2 cm², at least 3 cm², at least 4 cm², at least 5 cm², or at least 10 cm².

Suitably, the substrate is mechanically robust, in particular non-friable. The substrate may be flexible. Alternatively, the substrate may be rigid.

The substrate may be made from, for example, polymer, fibrous materials including fabrics, paper, or cardboard.

The substrate may be water insoluble at a temperature below 25°C, below 30°C, below 40°C, below 50°C, below 60°C, below 70°C, or below 80°C. For example, the weight of the substrate may remain unchanged (less than 1 wt.% difference) when immersed in distilled water at one of the above temperatures for a period of one hour.

Alternatively, the substrate may be water soluble at a temperature below 25°C, below 30°C, below 40°C, below 50°C, below 60°C, below 70°C, or below 80°C. For example, the weight of the substrate may change by at least 5 wt.%, at least 10 wt.%, at least 20 wt.%, at least 30 wt.%, at least 40 wt.% at least 50 wt.%, or at least 75 wt.% when immersed in distilled water at one of the above temperatures for a period of one hour, or the substrate may completely dissolve when immersed as above.

The substrate may be free or substantially free of active ingredients, in particular homecare or personal care active ingredients.

Suitably, the multilayer structure is bonded to (e.g. directly bonded to) the substrate. Active ingredients

The one or more active ingredients are constituents which, either alone or in combination with other ingredients, impart a specific activity/benefit to the article which makes it suited to a particular application.

The active ingredient(s) are homecare and/or personal care active ingredients.

The homecare or personal care active ingredient(s) may be one or more actives selected from a cleaning active, a conditioning active, a care active, a cosmetic active, a fragrance active, a corrosive active or an abrasive active.

The one or more active ingredients may include 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 one or more active ingredients may include 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), an anti-corrosion active, or a polish active.

The one or more active ingredients may include a cosmetic active, such as a make-up colorant.

The one or more active ingredients may include a fragrance active, such as a perfume.

The one or more active ingredients may include a corrosive active, such as a paint stripper.

The one or more active ingredients may include an abrasive active, such as particles for scouring a surface.

The one or more active ingredients may comprise or consist of one or more surfactants. The surfactants may be selected form the group consisting of anionic, non-ionic, cationic, amphoteric/zwitterionic surfactants and mixtures thereof. The surfactants 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 wt.% of the multilayer structure. 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 of the multilayer structure.

The one or more active ingredients may be present in their active forms, i.e. the form which provides the desired activity/benefit. Alternatively, at least one active ingredient may be present in the form of a precursor (e.g. a protected compound) which becomes active in use to provide the desired activity/benefit.

The one or more active ingredients may be present as dispersed compounds, or in the form of solid particles.

The active ingredients may be present in all layers of the multilayer structure.

The active ingredients present in said first and second matrix materials may be the same. Alternatively, the first and second matrix materials may have different active ingredients, or a different combination of active ingredients. For example, the first matrix material may have a first active ingredient dispersed therein, and the second matrix material may have a second active ingredient dispersed therein, wherein the first matrix material is substantially free of the second active ingredient, and the second matrix material is substantially free of the first active ingredient. By“substantially free” we mean a small or negligible amount of the specified active ingredient is present in the matrix material, e.g. less than 1 wt.%, less than 0.5 wt.%, less than 0.1 wt.%, less than 0.01 wt.%, or less than 0.001 wt.% as a percentage of the weight of the layer. This can be useful when the first and second active ingredients are incompatible, e.g. reactive with one another.

The amount of the active ingredients provided as part of the article may correspond to a unit dose of each ingredient. In other words, the article may be a consumable or disposable article providing a unit dose of all active ingredients. Advantageously, this simplifies use of the article by a consumer, since they can use/apply the article until all of the active species are consumed.

Article forms

The article may be provided in a packaging material. For example, the article may be provided in a packet or container formed from, e.g. plastic, metal, paper or cardboard. Thus, the present invention also includes a product comprising an article as described above in a packaging material.

The article of the present invention may be a homecare article. By“homecare article” we mean an article intended for the treatment (including cleaning, caring or conditioning) of the home or any of its contents. For example, the article may be used for treating hard surfaces in the home, cleaning items such as dishes or other kitchen hardware, conditioning the atmosphere of the home (e.g. an air freshener), or may be used in laundry applications.

The article of the present invention may be a personal care article. By“personal care article” we mean an article intended for the treatment, cleaning, caring or conditioning of a person, for example for personal hygiene or beautification. For example, the article may be used for cleaning or conditioning the skin, hair or oral cavity, for applying or removing make-up, or applying deodorant or antiperspirant.

The article may be a surface-treating article, such as a hard-surface treating article.

The article may be a cleaning article, such as a surface-cleaning article, in particular a hard surface-cleaning article.

The article may be a surface-care article.

The article may be a surface-conditioning article, such as a skin-conditioning article.

The article may be suitable for delivering its active ingredients by being rubbed against a surface. Optionally, the layers are transferred to/deposited on said surface during rubbing.

The article may take the form of a pad (e.g. cleansing pad), a wipe, a cloth, a liner, or a tissue.

In particular, the article may take the form of a pad/wipe/cloth for rubbing on a surface. In such situations, at least one of the layers may be erodible upon rubbing on said surface. Rubbing said layers against a surface leads them to break down to release the active ingredients. In such situations, the pad/wipe/cloth may be a single-use (disposable) article, containing a unit dose of the one or more active ingredients.

Claims

CLAIMS:

1. An article for use in homecare or personal care applications, comprising a multilayer structure on a substrate, the multilayer structure comprising one or more active ingredients, wherein there are variations in the mechanical, structural or chemical properties of the layers across the multilayer structure.

2. An article according to claim 1 , wherein the plurality of layers comprises at least one layer of a first matrix material in contact with at least one layer of a second matrix material, wherein the first and second matrix materials have different mechanical properties, structural properties or chemical properties.

3. An article according to claim 2, wherein the first matrix material is more porous than the second matrix material.

4. An article according to claim 2 or 3, wherein the first and second matrix materials are porous, and the pore size of in the first matrix material is smaller than that of the second matrix material.

5. An article according to any one of claims 2 to 4, wherein the first matrix material is denser than the second matrix material.

6. An article according to any one of claims 2 to 5, wherein the first matrix material is less viscous than the second matrix material.

7. An article according to any one of claims 2 to 6, wherein the first matrix material is more water-soluble than the second matrix material.

8. An article according to any one of the preceding claims, wherein the bonding between layers is chemically or structurally different to the bonding within layers.

9. An article according to claim 8, wherein the matrix material is water-soluble, and the bonding between layers is broken down faster than the bonding within layers when the article is immersed in water.

10. An article according to any one of claims 2 to 9, wherein the matrix material is a gel.

1 1 An article according to any one of the preceding claims, comprising at least 4 layers in the multilayer structure.

12. An article according to any one of claims 2 to 7, comprising at least 4 layers of matrix material, wherein the first and second matrix materials alternate.

13. An article according to any one of the preceding claims, wherein the article is in the form of a wipe.

14. A method of forming an article according to any one of the preceding claims, involving applying a first layer of a gel composition comprising an active ingredient on a substrate and allowing the composition to solidify, applying further layers of gel composition comprising an active ingredient on said first layer, and allowing each layer to solidify before application of the subsequent layer.

15. A multilayer article for use in homecare or personal care applications, comprising at least 4 layers having one or more active ingredients dispersed therein, wherein there are variations in the mechanical, structural and/or chemical properties of the layers across the multilayer structure.