Cleaning roller for a cleaner head of a cleaning appliance

Abstract

A cleaning roller for a cleaner head of a cleaning appliance comprises a roller core 111, a melamine foam layer 113 disposed around the roller core and a permeable protective layer 115 disposed around

Description

B ACKGROUND Appliances for cleaning or treating surfaces may comprise a cleaner head that is placed in contact with the surface to be treated or cleaned during use. Some such cleaner heads comprise a cleaning roller for wiping the surface and absorbing liquids, such as cleaning liquids or spillages to be cleaned up, off the surface. SUMMARY At its broadest, the present application relates to a composite structure for a cleaner head of a cleaning appliance, the composite structure comprising a melamine foam layer and a permeable protective layer disposed on a surface of the melamine foam layer. The composite structure may be supported on a substrate (e.g. a roller core) in the cleaner head. The composite structure may be applicable to different geometries. For example, the composite structure may be applied in a cleaning roller (e g. where the melamine foam layer is disposed around a roller core, and the permeable protective layer is disposed around the melamine foam layer). The composite structure may also be applied in a cleaning pad (e.g. where a surface of the melamine foam layer is adjacent a cleaning pad substrate and the permeable protective layer is disposed on another surface of the melamine foam layer (e.g. a surface of the melamine foam layer opposite the surface adjacent a cleaning pad substrate)). According to a first aspect there is provided a cleaning roller for a cleaner head of a cleaning appliance, the cleaning roller comprising: a roller core; a melamine foam layer disposed around the roller core; and a permeable protective layer disposed around the melamine foam layer. Incorporating melamine foam into a composite structure for a cleaner head (e.g. in a cleaning roller or pad) provides a composite structure with a high absorption capacity for liquids, and also a high wicking rate / low strike through time for such liquids, due to the open-cell structure of the melamine foam. Moreover, melamine foam can provide improved stain removal due to the high hardness of the melamine foam and the ability of the foam to deform to the surface the composite structure (e.g. within a cleaning roller or pad) is applied to. Deformation of the melamine foam layer can assist in cleaning recesses in the surface the composite structure (e.g. within a cleaning roller or pad) is applied to (e.g. tile grout lines). However, melamine foam also has low resistance to tearing and cracking when used in a cleaner head (e.g. in a cleaning roller or pad). Accordingly, a protective layer is disposed around the melamine foam layer such as to protect the melamine foam layer by reducing the direct contact area between the melamine foam layer and a surface being cleaned, and thereby increase the lifetime of the melamine foam layer in the composite structure (e.g. in a cleaning roller or pad) compared to if no protective layer was provided. The melamine foam layer may comprise a foam of melamine-formaldehyde condensate e.g. an open cell foam of melamine-formaldehyde condensate. The melamine foam layer may cover at least a portion of an outer surface of the substrate (e.g. the roller core or pad substrate). By way of example, the roller core may have a surface of revolution (e.g. a substantially cylindrical outer surface) at least partially e.g. fully covered by the melamine foam layer. The melamine foam layer may be wrapped around (i.e. may partly or fully circumscribe) the roller core. The protective layer may cover at least a portion of an outer surface of the melamine foam layer. By way of example, the melamine foam layer may have a surface of revolution (e.g. a substantially cylindrical outer surface) at least partially e.g. fully covered by the protective layer. The protective layer may be wrapped around (i.e. may partly or fully circumscribe) the melamine foam layer. The protective layer may be a web or may comprise a web portion. In this way, one or more portions of the outer surface of the melamine layer may be exposed through the protective layer, such that the exposed portions of the surface can be contacted with a surface being cleaned. This contact may allow the melamine foam layer to contact the surface being cleaned, thereby enhancing the stain removal properties of the composite structure through the abrasive action of the melamine foam. The web or web portion may comprise a plurality of openings. The protective layer web or web portion may be provided as a mesh or a perforated layer. The web or web portion may comprise a plurality of openings and each opening may have an area greater than or equal to 0.15 mm2. Such openings provide sufficient area for the exposed portions of the melamine foam layer’s outer surface to come into contact with the surface being cleaned through the protective layer, in particular when pressure is applied to the composite structure (e.g. in a cleaning roller or pad) to cause deformation at the contact interface between the composite structure (e.g. in a cleaning roller or pad) and the surface being cleaned. The web or web portion may comprise a plurality of openings and each opening may have an area less than or equal to 4.00 mm2. Such an upper limit on the area of each opening reduces the wear rate and the likelihood of damage to the exposed portions of the melamine foam layer’s outer surface. The protective layer may have a hardness of less than Mohs hardness 3 or may have a hardness of less than Mohs hardness 2. The protective layer may comprise fibres having a Shore D hardness of greater than or equal to 70 and less than or equal to 90, e.g. about 80. This can avoid the protective layer excessively abrading or damaging surfaces the composite structure (e.g. in a cleaning roller or pad) is applied to. The protective layer may comprise a polyester fabric. Polyester fabric provides good abrasion resistance and stain removal properties for the composite structure (e.g. in a cleaning roller or pad), whilst also being soft enough not to damage surfaces being cleaned (e.g. polyester fibres have a Shore D hardness of about 80). The protective layer may comprise a non-woven fabric. Alternatively, the protective layer may comprise a woven fabric or a knitted fabric (e.g. a knitted sock or cuff). The protective layer may comprise fibres, and the protective layer may have an average fibre length of greater than or equal to 30 mm. The protective layer may comprise fibres, and the average fibre length may be less than or equal to 100 mm. Such fibre lengths result in reduced bobbling / pilling of the protective fabric over the lifetime of the composite structure (e.g. in a cleaning roller or pad), whilst also not complicating manufacture of the fabric. The average fibre length may be measured according to ISO standard ISO 6989:1981. The protective layer may have a thickness greater than or equal to 0.5 mm. Thicknesses of the protective layer greater than or equal to 0.5 mm reduce the rate of wear of the melamine foam layer compared to if the protective layer was thinner. Moreover, such thicknesses increase the maximum liquid absorption volume of the protective layer, such that liquids can be quickly absorbed into the melamine foam. The protective layer may have a thickness less than or equal to 2.0 mm. Thicknesses of the protective layer less than or equal to 2.0 mm increase the influence of the melamine foam layer on the properties of the composite structure (e.g. in a cleaning roller or pad), since the melamine foam layer is in closer proximity to the cleaning surface. Moreover, where the protective layer comprises a web or web portion, such thicknesses increase the contact area and contact pressure between the melamine foam and the surface being cleaned for a given pressure applied to the cleaner head, thereby improving the stain removal properties of the composite structure (e.g. in a cleaning roller or pad). Furthermore, such thicknesses reduce the time for liquid to wick through the protective layer and be absorbed by the melamine foam layer. The protective layer may be bonded to the melamine foam layer e.g. by a bonding layer such as a permeable bonding layer. Such attachment of the protective layer to the melamine foam layer provides secure connection of said layers, particularly during rotation of the cleaning roller or back-and-forth movement of a cleaning pad, and facilitates the transfer of liquid between the protective layer and the melamine foam layer due to its permeability. The bonding layer may comprise a bonding web. By using a bonding web e.g. a permeable bonding web, the rate of transfer of liquid between the protective layer and the melamine foam layer can be increased because of the increased proportion of the adjacent surfaces of these layers that does not have the material of the bonding layer interposed between the protective layer and the melamine foam layer, meaning not all of the liquid transferred between the protective layer and the melamine foam layer has to permeate through the material of the bonding layer. An open area of the bonding layer may be greater than an open area of the protective layer. The open area of a layer may be defined as the percentage of the surface area of that layer occupied by openings therethrough. In this way, permeation of liquid through the material of the bonding layer is not the rate-determining step for the uptake of liquid by the composite structure (e.g. in a cleaning roller or pad) and the transfer of that liquid to the melamine foam layer. The bonding layer may comprise a polyamide, for example, a nylon copolymer. Such bonding layers provide a high bonding strength that is able to withstand the shear stresses exerted on the bond by rotation of the cleaning roller against a surface being cleaned or back-and-forth movement of the cleaning pad over a surface being cleaned. The bonding layer may be heat-activated, i.e. bonding of the melamine foam layer to the protective layer may be effected by heating of the bonding layer therebetween. This can facilitate manufacture of the composite structure (e.g. in a cleaning roller or pad). The protective layer may be stitched to the melamine foam layer. Where stitching of the protective layer and melamine foam layer together is used in place of a bonding layer interposed therebetween, the rate of transfer of liquid between the protective layer and the melamine foam layer can be increased due to the increased proportion of the adjacent surfaces of those layers that are in direct contact with each other. The liquid wicking rate of the protective layer may be greater than the liquid wicking rate of the melamine foam layer and / or the STT of the protective layer may be less than the STT of the melamine foam layer. The liquid wicking rate of the protective layer and the melamine foam layer may be measured according to ISO 9073-6:2000. The STT of the protective layer and the melamine foam layer may be measured according to ISO 9073-13:2023 or NWSP 70.3 Liquid Strike-Through. The protective layer may have a strike through time (STT) of less than 0.9 seconds, e.g. less than 0.89 seconds. The melamine foam layer may have a STT of greater than or equal to 0.9 s e.g. greater than or equal to 0.89 s. The melamine foam layer may have a STT of less than 1.1s e.g. less than or equal to 1.01 s. In this way, transport of liquid through the protective layer is not the rate-determining step for the uptake and transfer of liquid to the melamine foam layer, and liquid can be quickly absorbed by the composite structure (e.g. in a cleaning roller or pad). The liquid wicking rate of the bonding layer may be greater than or equal to 90% of the liquid wicking rate of the protective layer and / or the melamine foam layer. The liquid wicking rate of the bonding layer may be measured according to ISO 9073-6:2000. The STT of the bonding layer may be less than or equal to 110% of the STT of the protective layer and / or the melamine foam layer. The STT of the bonding layer may be measured according to ISO 9073-13:2023 or NWSP 70.3 Liquid Strike-Through. In this way, permeation of liquid through the material of the bonding layer does not substantially slow the uptake of liquid by the composite structure (e.g. in a cleaning roller or pad) and the transfer of that liquid to the melamine foam layer. The melamine foam layer may comprise uncompressed melamine foam. Uncompressed melamine foam may provide the melamine foam layer with a very high liquid absorption capacity of around 100 g water / g melamine foam (e.g. between 100 g water / g melamine foam and Illg water / g melamine foam). Uncompressed melamine foam may also have high deformability (e.g. 40% deformation under a pressure of between 7 and 13 kPa, as measured according to DIN53577). Uncompressed melamine foam may be defined as melamine foam having a density of about 8 kg m-3 to 11 kg m-3 and / or a porosity greater than or equal to 99%. The air permeability of uncompressed melamine foam may be around 315 L m’2 s'1 (e.g. greater than or equal to 275 L m’2 s’1 and less than or equal to 350 L m’2 s’1). The air permeability may be measured according to ISO 7231:2023. Uncompressed melamine foam may have a STT of greater than or equal to 0.89 s and less than or equal to 1.01 s (STT may be measured according to ISO 9073-13:2023 or NWSP 70.3 Liquid Strike-Through). A combined structure of the protective layer and the uncompressed melamine foam layer, when bonded together (e.g. with the above-described bonding layer), may have a STT of greater than or equal to 0.84 s and less than or equal to 1.10 s (STT may be measured according to ISO 9073-13:2023 or NWSP 70.3 Liquid Strike-Through). Said combined structure may have an air permeability of greater than or equal to 275 L m’2 s’1 and less than or equal to 305 L m’2 s’1, e.g. about 290 L m’2 s’1 (air permeability may be measured according to ISO 7231:2023). Said combined structure may have a liquid absorption capacity of greater than or equal to 30 g water / g material (i.e. the mass of the melamine foam, bonding layer and protective layer) and less than or equal to 85 g water / g material (e.g. around 35 g water / g material. The melamine foam layer may comprise compressed melamine foam. The melamine foam layer comprising compressed melamine foam can make manufacture of the composite structure (e.g. in a cleaning roller or pad) easier compared to if it comprises uncompressed melamine foam, whilst still providing high liquid absorption capacities of 38 g water / g melamine foam to 68 g water / g melamine foam. Compressed melamine foam may be defined as melamine foam having a density of 22 kg m-3 to 66 kg m-3 and / or a porosity between 16% and 50%. A combined structure of the protective layer and the compressed melamine foam layer, when bonded together (e.g. with the above-described bonding layer), may have a liquid absorption capacity of greater than or equal to 20 g water / g material (i.e. the mass of the melamine foam, bonding layer and protective layer) and less than or equal to 50 g water / g material. The melamine foam layer may be bonded to the substrate (e.g. roller core or pad substrate) by an adhesive layer. Adhesive bonding provides a simple and secure means of attachment of the melamine foam layer to the substrate. The adhesive layer may be impermeable. The melamine foam may have a thickness of greater than or equal to 2 mm. The melamine foam may have a thickness of less than or equal to 10 mm. Thicknesses in the range of 2 mm to 10 mm provide a balance between the total liquid capacity of the melamine foam layer (increased by using a greater thickness) and the likelihood of cracking the melamine foam layer during manufacture, e.g. if the cleaning roller is manufactured by wrapping the melamine foam layer around the roller core (reduced by using a reduced thickness). The roller core may be substantially cylindrical (e.g. a hollow cylinder or a solid cylinder). The roller core may have a diameter of about 50 mm. Such a diameter may reduce the likelihood of cracking the melamine foam layer during manufacture, e.g. if the cleaning roller is manufactured by wrapping the melamine foam layer around the roller core, compared to using a smaller diameter roller core. The cleaning roller may have a length between 200 mm and 700 mm. In a second aspect, there is provided a cleaner head for a cleaning appliance, the cleaner head comprising the above-described composite structure, e.g. in a cleaning roller according to the first aspect, or in a cleaning pad. Any optional features set out above in relation to the composite structure or the first aspect may equally be applied to the cleaner head according to the second aspect, except for where such a combination is evidently impermissible or expressly avoided. The cleaning roller may be rotatably mounted to a main housing of the cleaner head. The cleaning roller may be mounted to the main housing via the roller core (e.g. the roller core may be mounted to the main housing). The cleaner head may be a wet-dry floor cleaning tool. The cleaner head may further comprise a hydration system which circulates cleaning fluid through a cavity (e.g. a roller cavity or pad cavity) that the composite structure (e.g. within a cleaning roller or pad) is received in for wetting the floor surface and cleaning the composite structure (e.g. in a cleaning roller or pad). The hydration system may comprise a fluid inlet mounted in a housing of the cleaner head to deliver cleaning fluid to the cavity above the composite structure. Where the cleaner head comprises a cleaning roller, the cleaner head may further comprise a catchment tray arrangement positioned within the housing adjacent the cleaning roller and configured to collect dirty fluid and / or debris from the cleaning roller as it rotates. The cleaner head may further comprise a pump arranged to remove fluid from the catchment tray, e.g. for filtering and recirculation. The cleaner head may be a hard floor cleaning tool. As such, the cleaning roller may be configured to act as a sweeper element, or the cleaner head may further comprise a separate sweeper element. The cleaning roller or cleaning pad may be detachable from the cleaner head. This allows the cleaning roller or cleaning pad to be replaced, for example, when the composite structure is worn-out. Although the cleaner heads in the embodiments discussed below are described in relation to a hand operated floor cleaner, the cleaner heads may alternatively be provided on a robotic floor cleaner. Accordingly, there is also described herein a robotic floor cleaner comprising a cleaner head as described above. In a third aspect there is provided a cleaning appliance comprising the above-described composite structure, a cleaning roller according to the first aspect, or a cleaner head according to the second aspect. Any optional features set out above in relation to the composite structure or the first and second aspects may equally be applied to the cleaning appliance according to the third aspect, except for where such a combination is evidently impermissible or expressly avoided. The cleaning appliance may further comprise a main unit to which the cleaner head is releasably connectable. The cleaning appliance may further comprise a wand configured to connect the main unit to the cleaner head. The main unit and cleaner head may be connectable (e.g. connectable by the wand) such that they are fluidly and electrically connected. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a cleaning appliance; Figure 2 is a schematic of a cross-sectional view of a cleaner head; Figure 3a is a cross-sectional view of a cleaning roller in a plane perpendicular to the axis of rotation; and Figure 3b is a cross-sectional view of a cleaning roller in a plane through the axis of rotation. DETAILED DESCRIPTION Figure 1 provides a perspective view of a cleaning appliance 1. The cleaning appliance 1 comprises a main unit 200 that is fluidly and electrically connected to a cleaner head 100 via a wand 300. That is, a proximal end of the wand 300 is connected to the main unit 200 and a distal end of the wand 300 is connected to the cleaner head 100. The wand 300 provides fluid and electrical connection between the main unit 200 and the cleaner head 100. In this way, the cleaner head 100 is disposed at one end of the cleaning appliance 1, and the main unit 200 can be held by the user to allow the user to manoeuvre the cleaner head 100 over a surface. By the cleaner head 100 and main unit 200 being connected together by the wand 300, the cleaner head 100 can be manoeuvred over the surface from a standing position. Figure 2 shows a cross-sectional view of the cleaner head 100 of Figure 1. During normal use, the cleaner head 100 is moved forwards and backwards over the floor 2 in the ‘movement axis’ as indicated by double-headed arrow M. The cleaner head 100 comprises a main housing 104 defining a cavity 106 that opens onto the floor surface 2 and which receives two elongate cleaning rollers 110. The cleaning rollers 110 are arranged in parallel within the cavity 106 to contact the surface 2 when the cleaner head 100 is arranged for use. The cleaner head 100 is generally symmetrical about a central plane 122 that extends between the two parallel cleaning rollers 110 so that the cleaner head 100 can be operated bi-directionally. Each cleaning roller 110 is generally cylindrical in shape and extends between two cleaning roller ends to define a longitudinal axis 119, about which the cleaning roller 110 is configured to rotate when mounted in the cleaner head 100. In use, the cleaning rollers 110 are mounted within the cavity 106 with their roller axes 119 generally parallel to the floor surface 2 and generally perpendicular to the in-use direction of movement M of the cleaner head 100. The cleaning rollers 110 are powered to rotate about their respective longitudinal axes 119 by one or more motors (not shown). When in use, the cleaning rollers 110 are powered to rotate in opposite directions so that the innermost sides 117 of the cleaning rollers 110 that are closest to the central plane 122 rotate upwardly away from the surface 2, while the outermost sides 118 of the cleaning rollers 110 spaced furthest from the central plane 122 rotate downwardly towards the surface 2. In the context of this description, it will be understood that the innermost side 117 of a cleaning roller 110 is the portion of that cleaning roller 110 which is between the longitudinal axis 119 of that cleaning roller 110 and the central plane 122 of the cleaner head 100, while the outermost side 118 is the other side of the cleaning roller 110 opposite from the innermost side 117. With reference to the view shown in Figure 2, the left-hand cleaning roller 110 is configured to rotate anticlockwise (as shown by arrow Ra) and the right-hand cleaning roller 110 is configured to rotate clockwise (as shown by arrow Rc). As such, in use, the cleaning rollers 110 rotate against the floor surface 2 to push debris and moisture tangentially (to the outer cylindrical surface of the roller) towards the central plane 22 into the housing cavity 16, as indicated by arrows T. The cleaner head 100 is a wet-dry floor cleaning tool, and therefore comprises a hydration system which circulates cleaning fluid through the cavity 106 for wetting the surface 2 and cleaning the cleaning rollers 110. As such, the hydration system comprises a pair of fluid inlets 130 (one for each cleaning roller 110), each mounted in the housing 104 to deliver cleaning fluid to the cavity 106 above each cleaning roller 110. The cleaner head 100 further comprises a catchment tray arrangement 132 positioned within the main housing 104 between the two cleaning rollers 110 and configured to collect dirty fluid and debris from the cleaning rollers 110 as they rotate. A pump (not shown) is arranged to remove fluid from the catchment tray 132 for filtering and recirculation to the fluid inlets 130. Figure 3A is a schematic cross-sectional view of the layer structure of one of the cleaning rollers 110 in Figure 2 in a plane perpendicular to the longitudinal axis 119 of the cleaning roller 110. Figure 3B is a section view along plane A-A’ that passes along the longitudinal axis 119, the axial length of the cleaning roller 110 (typically between 200 mm and 700 mm) being truncated in Figure 3B. The cleaning roller 110 comprises a multi-layer structure. At the axial centre of the cleaning roller 110 is a roller core 111 that the longitudinal axis 119 of the cleaning roller 110 extends through; the cleaning roller 110 is mounted to the main housing 104 via the roller core 111 such that the roller can be rotated about its longitudinal axis 119. In the case of Figure 3 A, the roller core 111 is a solid cylinder, but it may also be provided as a hollow cylindrical structure. Disposed around the roller core 111 is a melamine foam layer 113 that covers the outer cylindrical surface of the roller core 111. Figure 3 A illustrates how the melamine foam layer 113 covers the entire circumference of the roller core 111, and Figure 3B shows that the melamine foam layer 113 also covers the entire axial extent of the roller core 111. The melamine foam layer 113 is bonded to the roller core 111 at the interface therebetween by an adhesive layer 112 that is radially interposed between the melamine foam layer 113 and the roller core 111, such that when the roller core 111 is rotated by the motor of the cleaner head 100, the melamine foam layer 113 is also rotated. The open cell foam of melamine formaldehyde within the melamine foam layer 113 provides the cleaning roller 110 with a high absorption capacity for liquids, and also a high wicking rate for such liquids, such that the cleaning roller 110 can take up liquid dispensed from the fluid inlets 130 and / or spilled liquids on the surface being cleaned. The melamine foam layer 113 is discussed in further detail below. To protect the melamine foam layer 113 from tearing, cracking and other forms of wear as a result of being rotated against the surface being cleaned, the cleaning roller 110 further comprises a permeable protective layer 115 disposed around the melamine foam layer 113 such that the cylindrical outer surface of the melamine foam layer is covered by the protective layer 115. Together, Figures 3A and 3B illustrate how the axial and circumferential extent of the melamine foam layer 113 is covered by the protective layer 115. The permeability of the protective layer 115 not only allows the protective layer 115 to absorb liquids, but also to wick those liquids into contact with the melamine foam layer 113, to which the liquid can be transferred. In this way, the liquid-storage capacity of the melamine foam layer 113 can be utilised whilst protecting the melamine foam layer 113 from rapid abrasive wear and damage. The protective layer 115 is discussed in further detail below. Similarly to the interface between the melamine foam layer 113 and the roller core 111, at the interface between the melamine foam layer 113 and the protective layer 115 the melamine foam layer 113 is attached to the protective layer 115 to prevent relative movement therebetween during rotation of the cleaning roller 110. In the case of the cleaning roller 110 in Figure 3 A, this is achieved by a permeable bonding layer 114. The permeability of the bonding layer 114 is important for allowing liquid transfer between the permeable protective layer 115 and the melamine foam layer 113. Alternatively to the arrangement illustrated in Figure 3A, the protective layer 115 can be stitched to the melamine foam layer 113. The bonding layer 114 is discussed in further detail below. Melamine Foam Layer The use of melamine foam within the cleaning roller 110 provides several useful properties for a wet-dry floor cleaning tool. The high porosity (greater than or equal to 99% for uncompressed melamine foam) and open cell structure of the melamine foam provides a very high liquid absorption capacity (up to 111 g water / g melamine foam) and fast liquid wicking. On a macro-scale, the melamine foam is also highly deformable (e.g. 40% deformation under a pressure of between 7 and 13 kPa), which allows the cleaning roller 110 to conform to recesses and protrusions in the surface (e.g. extend into tile grout lines) and thus provide enhanced cleaning of such surface features. Compressed or uncompressed melamine foam may be used within the melamine foam layer 113. The melamine foam layer 113 typically has a thickness of between 2 mm and 10 mm as part of a cleaning roller 110 having an outer diameter of approximately 65 - 75 mm. Because liquid is not transferred from the melamine foam layer 113 to the roller core 111, unlike at the interface between the melamine foam layer 113 and the protective layer 115, the attachment mechanism between the melamine foam layer 113 and the roller core 111 does not need to be permeable. Accordingly, a non-permeable adhesive 112 is used to attach the melamine foam layer 113 onto the roller core 111. Although on a macro scale, the melamine foam layer 113 is highly deformable, the solid melamine-formaldehyde condensate material making up the structure of the foam is hard (about Mohs hardness 4), which makes it an effective abrasive, as is discussed further below in relation to the structure of the protective layer. Protective Layer The protective layer 115 serves three primary functions within the cleaning roller 110: a) initial uptake of liquid from the surface being cleaned, b) wiping the surface as the cleaning roller 110 is rotated against it, and c) protecting the melamine foam layer 113 from rapid wear and cracking. To provide functions a) - c), the protective layer 115 is typically formed of a polyester fabric (either woven or non-woven). The polyester fabric is also in the form of a web (not illustrated in the schematics of Figures 3 A and 3B), comprising a plurality of openings, each with an area of approximately 1.0 mm2. Initial uptake of liquid by the protective layer 115 is facilitated by its permeability, with liquid being wicked along pores between the polyester fibres. The strike through time (STT) of the polyester fabric is less than 0.89 seconds, and thus the polyester fabric has a greater liquid wicking rate than the melamine foam layer (which has a STT between 0.89 seconds and 1.01 seconds), such that the wicking of the liquid through the protective layer 115 is not the rate-determining step for uptake and transfer of liquid to the melamine foam layer 113. The openings in the protective layer 115 also increase the rate of liquid transfer to the melamine foam layer 113 by increasing the permeability of the protective layer 115. Polyester is also a suitable fabric for repeated wiping against the surface being cleaned as the cleaning roller 110 is rotated. This is because the long polyester fibres (the polyester fibre typically having an average fibre length of 30 - 100 mm) are resistant to pulling out of the fibre even under the shear stress of the cleaning roller 110 rotating against the surface, and thus bobbling / pilling of the protective layer 115 is reduced compared to fabrics with shorter average fibre lengths, and the individual polyester fibres have high tensile strengths. Moreover, having a Shore D hardness of approximately 80, the polyester fibres are softer than the softest surfaces (around Mohs hardness 2) that the cleaning roller 110 is intended to be used on, which thereby limits excessive abrasion of such surfaces by the cleaning roller 110. The abrasion resistance of polyester fabric (due to the resistance to pulling out of fibres and the high tensile strength of fibres) also makes it a suitable material for protecting the melamine foam layer 113. By the protective layer 115 having a web structure, there are portions of the outer surface of the cleaning roller 110 where the melamine foam layer 113 is exposed through the openings of the protective layer 115. The protective layer 115 typically has a thickness of 0.5 mm - 2 mm, which allows the exposed portions of the melamine foam layer 113 to come into contact with the surface being cleaned as the cleaning roller 110 is rotated against the surface and deformed at the interface therebetween. Whilst this direct contact between the surface being cleaned and the melamine foam layer 113 results in an increase in the wear rate of the melamine foam layer 113, it also allows for abrasion of stains on the surface being cleaned by the melamine foam. The high-hardness (about Mohs hardness 4) melamine-formaldehyde condensate material makes it an effective abrasive against stains and dirt adhered to the surface, and thus its direct contact with the surface enhances the stain removal properties of the cleaning roller 110. The contact area between the melamine foam layer 113 and the surface being cleaned, and thus the balance between the stain removal performance of the cleaning roller 110 and the wear rate of the melamine foam layer 113, can be set by the size and number of openings in the protective layer 115, and the thickness of the protective layer 115. Bonding Laver To withstand the shear forces at the interface between the protective layer 115 and the melamine foam layer 113 during rotation of the cleaning roller 110 against the surface being cleaned, secure attachment of these layers is desirable. Moreover, to allow for effective liquid uptake into the melamine foam layer 113, an attachment mechanism between the layers should be permeable. As discussed above, in the case of the cleaning roller 110 in Figures 3A and 3B, the protective layer 115 and melamine foam layer 113 are bonded together by a permeable bonding layer 114. The bonding layer 114 comprises nylon copolymer web that provides a strong, heat-activated, bond between the layers. The permeable and webbed nature of the bonding layer 114 results in little impact on the wicking of liquid into the melamine foam layer 113 from the protective layer 115 and allows the melamine foam to be exposed through the openings in the protective layer 115 as discussed above. An example of a suitable material is Freudenberg® M1590 Co PA. Typically, the open area of the of the webbed bonding layer 114 is greater than an open area of the webbed protective layer 115. As an alternative to the bonding layer 114 in Figures 3A and 3B, in another cleaning roller 5 110 the protective layer 115 may be attached to the melamine foam layer 113 by stitching, which increases the rate of transfer of liquid between the protective layer 115 and the melamine foam layer 113 compared to the permeable bonding layer 114 but may provide less secure attachment than the bonding layer 114.

Claims

1. A cleaning roller for a cleaner head of a cleaning appliance, the cleaning roller comprising: a roller core;a melamine foam layer disposed around the roller core; anda permeable protective layer disposed around the melamine foam layer.

2. The cleaning roller according to claim 1, wherein the protective layer is a web.

3. The cleaning roller according to claim 2, wherein:the web comprises a plurality of openings; andeach opening has an area greater than or equal to 0.15 mm2 and less than or equal to 4.00 mm2.

4. The cleaning roller according to any preceding claim, wherein the protective layer comprises a polyester fabric.

5. The cleaning roller according to any preceding claim, wherein the protective layer comprises a non-woven fabric.

6. The cleaning roller according to any preceding claim, wherein the protective layer comprises fibres and has an average fibre length greater than or equal to 30 mm7. The cleaning roller according to any preceding claim, wherein the protective layer has a thickness greater than or equal to 0.5 mm and less than or equal to 2.0 mm.

8. The cleaning roller according to any preceding claim, wherein the protective layer is bonded to the melamine foam layer by a permeable bonding layer.

9. The cleaning roller according to claim 8, wherein the bonding layer comprises a bonding web.

10. The cleaning roller according to claim 9, wherein an open area of the bonding layer is greater than an open area of the protective layer.

11. The cleaning roller according to any of claims 8 to 10, wherein the bonding layer comprises a polyamide.

12. The cleaning roller according to any of claims 1 to 7, wherein the protective layer is stitched to the melamine foam layer.

13. The cleaning roller according to any preceding claim, wherein the liquid wicking rate of the protective layer is greater than the liquid wicking rate of the melamine foam layer.

14. The cleaning roller according to any preceding claim, wherein the melamine foam layer comprises uncompressed melamine foam.

15. The cleaning roller according to any of claims 1 to 13, wherein the melamine foam layer comprises compressed melamine foam.

16. A cleaner head for a cleaning appliance, the cleaner head comprising a cleaning roller according to any preceding claim.

17. A cleaning appliance comprising a cleaning roller according to any of claims 1 to 15, or a cleaner head according to claim 16.19

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