CLEANING SPONGE AND METHOD FOR ITS MANUFACTURING

Description

[0001] The invention relates to a cleaning sponge with a carrier body made of a foam material and with a coating on at least one of the main surfaces of the carrier body, as well as to a method for producing the cleaning sponge. The cleaning sponge is particularly suitable for cleaning dining and cooking utensils, but also for cleaning any other surfaces, for example, in the kitchen and bathroom.

[0002] Cleaning sponges typically consist of a foam base that serves as a carrier for a coating, with the coating being the actual cleaning component. The coating should be able to remove even heavy soils, such as dried-on, encrusted food residue, but should also not scratch delicate surfaces such as Teflon-coated surfaces.

[0003] Cleaning sponges that clean relatively gently are commercially available. They consist of a polyurethane foam base with a polyurethane coating containing plastic particles, such as high-density polyethylene or polypropylene. When pressure is applied, the particles are pressed into the dirt and can damage it, making it more accessible to cleaning fluid. The plastic particles are comparatively soft, so there is no risk of scratching most surfaces during cleaning. The cleaning effect can be enhanced by a three-dimensional surface texture of the cleaning surface, i.e., the cleaning surface has alternating raised and recessed areas. Cleaning sponges with nonwoven layers made of plastic fibers are also known.

[0004] US 6,352,567 B1 discloses an abrasive article comprising a carrier body made of a nonwoven fabric, wherein the nonwoven fabric contains a binder layer and a slurry layer. Abrasive particles are distributed in both the binder layer and the slurry layer; these can be organic particles or inorganic particles of varying hardness.

[0005] EP 3 424 642 A1 discloses a porous material for a polishing tool. The material comprises an anisotropic elastic foam body impregnated with a binder containing abrasive particles.

[0006] US 2018 / 0028036 A1 discloses a scouring body with a substrate made of, for example, a foam material and a structural layer on the substrate. The structural layer consists of a binder in which a plurality of ceramic or organic microparticles are dispersed.

[0007] WO 02 / 090483 A2 discloses an impregnated wipe suitable for cleaning hard surfaces. The wipe has a structured surface with abrasive properties and is impregnated with a cleaning agent.

[0008] DE 10 2006 005 160 A1 discloses a scouring body comprising a sponge body, a textile fabric on the sponge body, and an abrasive composition on the fabric. The abrasive composition contains abrasive particles.

[0009] A disadvantage of conventional cleaning sponges is that the mechanical forces that occur during use cause plastic particles to detach from the coating or plastic fibers to detach from the fleece. Over the course of a sponge's service life, the mechanical stresses of cleaning cause a certain amount of wear on the coating or fleece. As a cleaning sponge ages, more and more plastic particles are released from the coating or plastic fibers to detach from the fleece and enter the cleaning fluid used, such as dishwashing water, in the form of so-called "microplastics." The cleaning fluid, in turn, is usually discharged into the sewer system and, along with other wastewater, ends up in treatment plants, where the microplastics cause significant problems. They cannot be removed from wastewater using special filters, or can only be removed with great effort.In most wastewater treatment plants, microplastics cannot be removed at all, meaning they enter drinking water and ultimately the bodies of humans and animals, where they can have harmful effects on health. The exact consequences of microplastics for humans, animals, and the environment are still completely unclear. However, it is certain that microplastics in seawater lead to physiological disorders, increased tumor formation, and increased mortality in marine animals. Therefore, there is concern that microplastics can also harm humans.

[0010] It is undoubtedly desirable to prevent the release of microplastics into wastewater.

[0011] The object of the present invention is therefore to provide a cleaning sponge that avoids the problems of the prior art and releases no or at least hardly any microplastics during use, yet still cleans efficiently and gently. The cleaning sponge should be as universally usable as possible for cleaning different surfaces and be particularly suitable for use in cleaning tableware and cookware such as pots and pans, including cookware with scratch-sensitive surfaces such as Teflon coatings or other non-stick coatings.

[0012] The object is achieved by the cleaning sponge as claimed in independent claim 1, as well as by the methods for producing the cleaning sponge as claimed in independent claims 11 and 12. Advantageous embodiments are claimed in the respective dependent claims.

[0013] The cleaning sponge and methods for its production are aspects of the same invention. Statements relating to one aspect of the invention therefore apply equally to the other aspect of the invention.

[0014] The cleaning sponge according to the invention consists of a carrier body which is provided with a coating, wherein the coating represents the component which fulfils the actual cleaning task.

[0015] The carrier body is of a conventional type. It is a foam body with two opposing main surfaces, one or both of which can be coated with a coating according to the invention. The dimensions are advantageously chosen so that the cleaning sponge has the largest possible cleaning surface, is sufficiently thick to prevent tearing, and fits comfortably in the hand of the person cleaning.

[0016] In principle, any foam material that is stable under cleaning conditions—that is, that can withstand the mechanical forces acting on the sponge during a cleaning process and that is also resistant to water and common cleaning agents—can be used for the carrier body of the cleaning sponge. Polyurethane is a proven material. According to the invention, foam bodies made of polyurethane are preferred for the carrier body.

[0017] Polyurethane is a plastic that decomposes under the influence of UV light (daylight) and moisture and is also broken down by microorganisms in the final stage. Cleaning sponges made of polyurethane foam can therefore lead to the formation of microplastics after disposal. This microplastic, which can arise at some point during the decomposition of a disposed cleaning sponge, does not usually end up in wastewater. Nevertheless, it may be desirable to minimize the amount of polyurethane used. Within the scope of this invention, according to a further preferred embodiment, a composite body consisting of at least two foam material layers bonded to one another by means of an adhesive layer is used as the carrier body. One of the layers consists of a natural material that does not lead to microplastics upon degradation, for example a cellulose-based material such as viscose.The surface of the carrier body provided with the coating is preferably a polyurethane surface, which is why a cleaning sponge provided with a coating according to the invention on both sides preferably has either a carrier body made of polyurethane foam or a sandwich-like composite carrier body with a central viscose foam layer and two outer layers of polyurethane foam. This ensures the best adhesion between the polyurethane binder of the coating and the coated surface.

[0018] Alternatively, a composite carrier body made of at least two foam materials bonded together by an adhesive layer can have a layer made of a material with special cleaning properties instead of a layer made of a natural material. Such a layer is, for example, a layer made of melamine resin. Open-pored melamine resin sponges are known as "dirt erasers." Such foams can also be advantageously used in the present invention. In a composite body made of a foam material such as polyurethane and a melamine resin foam material, the cleaning coating is naturally not located on the melamine resin layer, but on the layer made of the other foam material.

[0019] A polyurethane adhesive is preferably used to bond the layers of the composite carrier body to one another, in particular if at least one of the layers consists of polyurethane.

[0020] The surface of the carrier body to be coated can be flat, i.e., level, or have a three-dimensional surface structure. Three-dimensional surface structures include, for example, groove-like elevations and depressions arranged alternately, or island-like elevations and depressions forming a grid. Such structuring of the carrier body surface is transferred to the coating and can improve the cleaning effect, since, on the one hand, the raised areas can contribute to breaking up the contaminants, and, on the other hand, the detached contaminants can be absorbed by the depressions and transported away by the cleaning fluid. The cleaning surface is therefore not blocked by detached contaminants.

[0021] The coating consists of at least two types of components, the cleaning particles and a binder in which the particles are distributed and which binds them to a surface of the carrier body.

[0022] A polyurethane or a mixture of polyurethanes is used as the binder in the present invention. Like the carrier body, the polyurethane binder must be chemically and mechanically stable under cleaning conditions. When selecting a suitable polyurethane binder, it is also preferable to consider criteria such as its viscosity in the uncrosslinked state, as well as its hardness and elongation at break in the crosslinked state.

[0023] Viscosity is particularly important with regard to good application properties and good anchoring of the coating to the surface of the carrier body. Preferably, the binder should be sufficiently viscous to prevent penetration into the interior of the carrier body, but still sufficiently fluid to allow penetration into the surface pores of the carrier body, thereby achieving improved fixation of the coating to the carrier body. The viscosity of the polyurethane binder is preferably in the range of 1,000 to 12,000 mPas, or the viscosity of the coating composition is in the range of 5,000 to 12,000 mPas, particularly preferably in the range of 7,000 to 10,000 mPas.

[0024] In the present invention, the term "viscosity" refers to dynamic viscosity. It is determined using a Brookfield viscometer according to ISO 2555.

[0025] The hardness of the coating plays a role in both its cleaning properties and the durability of the bond between the substrate and the coating. The coating's hardness should be sufficiently high to assist the cleaning particles during cleaning, but it must not be excessive, as the cleaning sponge must remain flexible overall. The Shore A hardness of the cured coating is preferably in the range of 25 to 85. A Shore A hardness of 40 to 70 is particularly preferred. Shore A hardness is determined according to ASTM D2240-00 using a Shore Durometer.

[0026] The elongation at break of the crosslinked coating is preferably in the range of 40 to 150%, particularly preferably in the range of 50 to 100%. An elongation at break in this range guarantees sufficient flexibility of the coating to allow it to follow the deformation of the soft substrate during a cleaning process. Sufficient elongation at break combined with a moderate hardness also ensures that the bond between the soft substrate and the coating remains stable under mechanical stress and deformation during the cleaning process. The elongation at break is determined according to ASTM D-3574, Method E. This is essentially a method for testing PU foam. However, the test principle can also be applied to flexible polymer films.

[0027] It has been found that one-component polyurethane resins, such as those known as assembly foams, are well suited for the purposes of the present invention. Naturally, no blowing agent is used in the present invention, since foam formation is undesirable. Solvents are also preferably not included. The proportion of free isocyanate groups in the prepolymers is preferably 3 to 10 wt.%. The one-component polyurethane resins cure at 20 to 25°C by reaction with atmospheric moisture over the course of several hours. Particularly preferred binders are polyurethane prepolymers based on a diphenylmethane diisocyanate adduct with diols and triols. One commercially available product is Everad RPM 2644 (from Everad Adhesives, France).

[0028] The polyurethane prepolymers can be prepared, for example, by reacting a diisocyanate, such as 4,4-diphenylmethane diisocyanate, with at least one diol and / or triol in the presence of a tin or amine catalyst. The diols and triols (i.e., polyols) used preferably have a molecular weight between 1,000 and 5,000 g / mol and a hydroxyl number between 40 and 100 mg KOH / g. Polyether polyols are particularly preferred. The molar ratio of isocyanate to polyol used is selected depending on the viscosity of the desired finished prepolymer. Typically, the molar ratio of isocyanate to polyol is in the range from 30:70 to 50:50.

[0029] One-component polyurethane resins are particularly preferred because they are very easy to process. However, the present invention is not limited to the use of one-component polyurethane resins.

[0030] The core of the present invention lies in the use of specific cleaning particles. According to the invention, the cleaning particles used are not plastic particles, but natural particles. These have the advantage that no microplastics enter the wastewater when particles detach from the coating during use of the cleaning sponge, especially after prolonged use. However, natural particles also have disadvantages compared to plastic particles. In particular, they tend to scratch sensitive surfaces and are less well adhered to the binding plastic than plastic particles. Therefore, there is a greater risk of particles detaching from the coating when using the cleaning sponge. While this is harmless from an environmental point of view, it does reduce the service life of the cleaning sponge.

[0031] According to the invention, it has now been discovered that certain natural materials, when used in a suitable size, do not have these disadvantages. Instead, they clean gently and are effectively and permanently fixed in the coating by a polyurethane binder. Cleaning sponges with a polyurethane coating containing such particles distributed throughout can therefore be used to clean delicate surfaces, such as Teflon-coated pans and other non-stick cookware, and they have a long service life.

[0032] The natural materials suitable for the purposes of the present invention can be divided into two groups. Particles of the first group are referred to hereinafter as "abrasive particles," and particles of the second group are referred to hereinafter as "non-abrasive particles." Both groups have in common that they clean very well and gently, but the cleaning properties of the particles of the first group are even better than those of the second group, while the particles of the second group clean even more gently than the particles of the first group.

[0033] Abrasive particles include pumice, quartz sand, glass, corundum, and calcined bauxite. These materials are ground to suitable particle sizes, preferably in the range of 20 µm to 1,000 µm. Particle sizes in the range of 50 µm to 500 µm are particularly suitable. A coating can use only a single particle type, for example, only pumice particles, or any mixture of several of the aforementioned particles can be used.

[0034] Grinding creates edges that are particularly well-suited for breaking up contaminants. At the same time, the materials are not so hard that they are overly abrasive and cause scratching of the treated surfaces. This is especially true for smaller particles in the 50 to 300 µm range.

[0035] The most suitable material from the first group is pumice, specifically pumice with a particle size in the range of 50 to 500 µm. This material perfectly embodies the desired properties. It is hard enough, and the edges of the particles created during grinding are sharp enough to have an abrasive cleaning effect, but at the same time, the hardness and sharpness of the edges are not so great that the surfaces to be cleaned can be easily scratched. An upper particle size limit of 500 µm is desirable because larger particles tend to break during the cleaning process, which can create sharp edges that are less effective at cleaning.

[0036] Pumice also has the advantage of being particularly well-bonded in the polyurethane binder. This is likely due to the porosity of the pumice particles.

[0037] Non-abrasive particles include precipitated silica, river sand, desert sand, and walnut shell powder. These particles can also be used individually, meaning only one type of particle in a coating, or in any combination of two or more types of particles.

[0038] Suitable particle sizes are preferably in the range of 20 µm to 1,000 µm, particularly preferred are particle sizes in the range of 100 µm to 500 µm, and the best and most gentle cleaning effect is achieved with particle sizes in the range of approximately 250 µm to 350 µm.

[0039] The following generally applies to both abrasive and non-abrasive particles: the larger the particles, the better the cleaning effect, and the smaller the particles, the more gentle the cleaning. In the present invention, the term "particle size" is to be understood as meaning that for a particle size of x µm to y µm, all particles pass through a sieve with a mesh size of y µm, but do not pass through a sieve with a mesh size of x µm.

[0040] The non-abrasive particles mentioned above have in common that they have a nearly rounded shape, meaning they lack any sharp edges. River sand is transported by the current and thus becomes rounded, while desert sand is transported by the wind and thus also becomes rounded. Grinding walnut shells produces a relatively soft powder without sharp edges.

[0041] Strictly speaking, precipitated silicon dioxide is not a "natural" material, as it is artificially produced by precipitation from water glass. However, since its chemical composition is identical to natural materials, it is considered a natural material in the present invention. Precipitated silicon dioxide, also commonly referred to as "silica," is the most suitable material from the group of non-abrasive particles for the purposes of the present invention. The hydrated silicon dioxide has no sharp edges. Rather, it is in the form of essentially round particles. It cleans particularly gently and is excellently fixed by the polyurethane binder, which is presumably due to the porosity of the silicon dioxide particles. The most suitable material for cleaning highly sensitive surfaces is therefore precipitated silicon dioxide with a particle size in the range of 100 µm to 500 µm.An example of a commercially available material is Sipernat 2200 from Dow Chemicals.

[0042] Walnut shell powder is also excellent, but it is not as easy to process as the other materials mentioned. It tends to foam the polyurethane when mixed with the polyurethane binder, which can lead to instability in the application process. It may be necessary to add defoamer to a coating composition containing walnut shell powder.

[0043] Coatings according to the invention can consist exclusively of polyurethane binder and cleaning particles distributed therein, but they can also contain other components, provided these do not adversely affect the properties of the coating. The coatings are generally colored, meaning that in addition to the polyurethane binder and the cleaning particles, they contain at least one coloring substance. Coloring substances are organic or inorganic pigments and inorganic or organic dyes. Unlike dyes, which are soluble, pigments consist of particles. When using pigments, care must be taken to avoid using pigments that are too hard or too large, to prevent the pigments from acting as "cleaning particles" and potentially scratching the surfaces to be cleaned. Suitable coloring substances are commercially available.One example is Hostaperm Yellow H3G from Clariant GmbH.

[0044] The proportion of the coloring substance in the coating should preferably not exceed approximately 4% by weight. A typical amount is approximately 0.5% by weight. The coating may contain other additives known per se in the field of plastic coatings, but preferably contains only polyurethane binders, cleaning particles, and optionally one or more coloring substances.

[0045] The production of a cleaning sponge according to the invention is preferably carried out in such a way that a polyurethane binder, cleaning particles and optionally a coloring substance and / or other auxiliary substances are mixed in the desired amounts to form a coating composition, after which the coating composition is applied to a main surface of a carrier body made of a foam material and is then cured in air.

[0046] The coating compositions preferably contain, in the case of abrasive cleaning particles, 60 to 80 wt.% polyurethane binder, the remainder abrasive particles, and up to 4 wt.% coloring substance, i.e., 16 to 40 wt.% abrasive cleaning particles. Particularly preferably, the compositions contain 65 to 70 wt.% polyurethane binder, 27.5 to 34.7 wt.% abrasive particles, and 0.3 to 2.5 wt.% inorganic and / or organic pigments. Pumice particles are preferably used as the abrasive particles, and a one-component polyurethane resin is preferably used as the polyurethane binder.

[0047] In the case of non-abrasive cleaning particles, the coating compositions preferably contain 75 to 95 wt.% polyurethane binder, the remainder non-abrasive particles, and up to 4 wt.% coloring substance, i.e., 1 to 25 wt.% non-abrasive particles. Particularly preferably, the coating compositions contain 82.5 to 89.5 wt.% polyurethane binder, 8 to 17.2 wt.% non-abrasive particles, and 0.3 to 2.5 wt.% inorganic and / or organic pigments. Silica particles are preferably used as the non-abrasive particles, and a one-component polyurethane resin is preferably used as the binder.

[0048] It is understood that the percentage shares add up to 100%.

[0049] The coating composition is preferably applied to a surface of the carrier body by roller application. Roller application methods are preferred in that they lead to particularly good anchoring of the cleaning particles in the polyurethane film and the coating result is very homogeneous and visually attractive. To achieve optimal coating results, a polyurethane resin is preferably selected that produces a coating composition with a viscosity in the range of 5,000 to 12,000 mPas, preferably 7,000 to 10,000 mPas. Such polyurethane resins have a viscosity in the range of 1,500 to 7,000 mPas.

[0050] The coating composition is then cured, meaning the polyurethane resin is crosslinked. The crosslinking conditions depend on the type of polyurethane resin used. A one-component polyurethane resin is preferred, which cures in air by reacting with atmospheric humidity at 20 to 25°C within 2 to 8 hours. At low air humidity (less than approximately 40%), it may be necessary to moisten the surface of the substrate to be coated with water before applying the coating composition.

[0051] Alternatively, the polyurethane resin can first be applied to a surface of the carrier body, for example by roller application or spraying, and then the abrasive or non-abrasive particles can be sprinkled onto the still-moist polyurethane resin film. In the case of roller application, a polyurethane resin with a viscosity in the range of 5,000 to 12,000 mPas, preferably 7,000 to 10,000 mPas, is preferably used. In the case of spraying the polyurethane resin, a polyurethane resin with a viscosity in the range of 1,000 to 5,000 mPas, preferably 1,500 to 3,000 mPas, is preferably used.

[0052] After the cleaning particles are sprinkled on, the polyurethane resin is crosslinked. The crosslinking conditions depend on the type of polyurethane resin used, with a one-component polyurethane resin being preferred, which cures in air by reacting with atmospheric humidity at 20 to 25°C within 2 to 8 hours.

[0053] The coating composition or polyurethane resin can be applied to a "finished" carrier body or composite carrier body, i.e., a carrier body with the dimensions of the cleaning sponge to be produced. Alternatively, a carrier body plate or composite carrier body plate can be coated, from which, after the coating has cured, the cleaning sponges are cut or punched out in the desired dimensions and shapes. Furthermore, after coating one of the surfaces of a (composite) carrier body and curing the coating, the opposite surface of the (composite) carrier body can also be coated with a coating according to the invention or a different coating.Furthermore, it is possible to first coat one of the layers (carrier body) in a composite carrier body and then to bond this coated carrier body to its uncoated surface with one or more further layers (for example made of cellulose or melamine resin).

[0054] Preferred coating thicknesses are in the range of 0.5 to 4 mm, particularly preferably in the range of 1 to 3 mm. Preferred coating weights are in the range of 200 to 500 g / m 2 , particularly preferably in the range of 250 to 400 g / m 2 .

[0055] The invention is further illustrated below with reference to figures. It should be noted that the figures are not to scale and are not proportional. Furthermore, features disclosed in connection with a specific figure should in no way be understood to mean that the respective features are only applicable in combination with the other features illustrated and / or described in the corresponding figure.

[0056] In the figures, like reference numerals designate like or corresponding elements. They show: Fig. 1 an embodiment of a cleaning sponge according to the invention, Fig. 2 an alternative embodiment of a cleaning sponge according to the invention, Fig. 3 a plan view of a cleaning sponge according to the invention, and Fig. 4 a section through the Fig. 3 cleaning sponge shown along the line A-A'.

[0057] Fig. 1shows an embodiment of a cleaning sponge 1 according to the invention. The cleaning sponge 1 shown has a carrier body 2 made of polyurethane foam material with a first main surface 2' and a second main surface 2". The first main surface 2' is covered by a coating 3 made of polyurethane with abrasive or non-abrasive particles 4 distributed therein. The surface 3' of the coating 3 forms the cleaning surface of the cleaning sponge 1. The particles 4 are in the Fig. 1illustrated embodiment, are distributed statistically in the coating 3, as is the case when a coating composition made of polyurethane resin with particles 4 dispersed therein is applied to the carrier body 2. If, on the other hand, the polyurethane resin is first applied to the carrier body 2 and then the particles 4 are scattered onto the not yet crosslinked polyurethane resin, the particles 4 are more localized on the surface 3' of the coating 3. If the particles 4 are localized more on the surface of the coating 3, fewer particles 4 are required than with a statistical distribution of the particles 4 throughout the entire volume of the coating 3. However, cleaning sponges with a statistical distribution of the particles 4 throughout the entire volume of the coating 3 have a longer service life because the particles 4 are anchored more permanently in the coating 3.

[0058] Fig. 2shows an alternative embodiment of a cleaning sponge 1 according to the invention. Fig. 2 In the embodiment shown, the carrier body is a composite body made of a polyurethane foam layer 5 and a viscose foam layer 7, which are bonded by an adhesive layer 6. The surface of the polyurethane foam layer not bonded to the viscose foam layer is provided with a coating 3 in which abrasive or non-abrasive particles 4 are randomly distributed. The surface 3' of the coating 3 represents the cleaning surface of the cleaning sponge 1.

[0059] The Fig. 2 The embodiment of the cleaning sponge 1 shown has essentially the shape of a cuboid, while the embodiment shown in Fig. 1The embodiment shown is rather cube-shaped. However, the shape of the cleaning sponges is basically arbitrary, although shapes that are easy (and therefore inexpensive) to manufacture are preferred. Shapes such as those in Fig. 1 and Fig. 2 The cleaning sponges shown can be punched out of foam sheets without waste, but the present invention is not limited to such shapes. Rather, the cleaning sponges according to the invention can also have any curved contours, for example, contours that allow for better access to hard-to-reach areas. Alternatively or additionally, opposite side surfaces of a cleaning sponge can have recesses that allow the cleaning sponge to be held more effectively and securely during a cleaning process.

[0060] In the Fig. 1 and Fig. 2In the cleaning sponges 1 shown, only one surface of the carrier body 2 is provided with a coating 3. Alternatively, however, the second main surface 2" could also be provided with a coating according to the invention or another coating. It is also possible to provide a coating 3 according to the invention with abrasive particles on one main surface of the carrier body 2 and to provide a coating 3 according to the invention with non-abrasive particles on the other main surface of the carrier body 2.

[0061] In addition, a carrier body 2 can also be a composite body made up of more than 2 layers bonded by means of an adhesive (as in Fig. 2 shown). For example, the Fig. 2The composite body shown can be bonded on the main surface 2" of the foam layer 7 made of viscose to a further foam layer made of polyurethane by means of a further adhesive layer, which in turn could have a coating 3 according to the present invention.

[0062] The Figures 1 and 2 The cleaning sponges 1 shown each have unstructured surfaces or main surfaces. However, the coating 3 according to the invention can be applied not only to flat surfaces, but also to surfaces with virtually any desired structure. An example of a cleaning sponge 1 with a structured surface is shown in the Figures 3 and 4 shown.

[0063] Fig. 3 shows a plan view of the cleaning surface 3' of a cleaning sponge 1 according to the invention, and Fig. 4 shows the Fig. 3 cleaning sponge shown in cross section along the line A-A'. As can be seen Fig. 3As can be seen, the surface 3' has a three-dimensional structure with elevations 8 and depressions 9 arranged alternately in a regular grid. Fig. 3 The maxima of the elevations 8 are shown as solid circles, while the minima of the depressions 9 are shown as dotted circles. The particles 4 are in Fig. 3 not shown. Viewed in cross section ( Fig. 4 ) such a grid forms a waveform.

[0064] The cleaning sponges according to the invention can also have any other three-dimensional surface structures, for example grooves, which can help to improve the cleaning effect.

[0065] The cleaning sponges according to the invention have a long service life. This also means they pollute the environment less with waste plastic than less durable and thus shorter-lived cleaning sponges. At the end of their service life, the cleaning sponges according to the invention can be decomposed by exposure to daylight (UV light) and moisture, and ultimately by microorganisms. Alternatively, thermal recycling is also possible.

Claims

1. Cleaning sponge (1) comprising a carrier body (2) of a foam material, which has two opposing main surfaces (2', 2"), and a coating (3) on at least one of the main surfaces of the carrier body (2), characterized in that the coating (3) consists of a composition comprising polyurethane and abrasive or non-abrasive particles (4) dispersed therein, wherein the abrasive particles (4) are selected from the group consisting of pumice particles, quartz sand particles, glass particles, corundum particles, particles of calcined bauxite and mixtures thereof, and have a size in the range from 20 µm to 1,000 µm, and the non-abrasive particles (4) are selected from the group consisting of precipitated silica, river sand, desert sand, walnut shell powder and mixtures thereof, and have a size in the range from 20 µm to 1,000 µm.

2. Cleaning sponge (1) according to claim 1, characterized in that the coating (3) contains pumice particles with a size of 20 to 500 µm.

3. Cleaning sponge (1) according to claim 1, characterized in that the coating (3) contains particles (4) of precipitated silica with a size of 100 to 500 µm.

4. Cleaning sponge (1) according to claim 1 or 2, characterized in that the coating (3) consists of a composition containing 60 to 80% by weight of polyurethane as binder, the remainder being abrasive particles (4) and up to 4% by weight of a colouring substance, preferably 65 to 70% by weight of polyurethane as binder, 27.5 to 34.7% by weight of pumice particles and 0.3 to 2.5% by weight of inorganic and / or organic pigments.

5. Cleaning sponge (1) according to claim 1 or 3, characterized in that the coating (3) consists of a composition containing 75 to 95% by weight of polyurethane as binder, the remainder being non-abrasive particles (4) and up to 4% by weight of a colouring substance, preferably 82.5 to 89.5% by weight of polyurethane as binder, 8 to 17.2% by weight of precipitated silica and 0.3 to 2.5% by weight of inorganic and / or organic pigments.

6. Cleaning sponge (1) according to any one of claims 1 to 5, characterized in that the coating (3) has a Shore A hardness of 25 to 85, preferably of 40 to 70.

7. Cleaning sponge (1) according to any one of claims 1 to 6, characterized in that the coating (3) has an elongation at break of 40 to 150%, preferably of 50 to 100%.

8. Cleaning sponge (1) according to any one of claims 1 to 7, characterized in that the carrier body (2) is a sponge body made of polyurethane or a composite body made of a sponge body (7) based on cellulose or melamine resin and a sponge body (5) made of polyurethane, which are bonded by means of a polyurethane adhesive (6), the coating (3) of the composite body being located on the sponge body (5) made of polyurethane.

9. Cleaning sponge (1) according to any one of claims 1 to 8, characterized in that at least one main surface (2') of the carrier body (2) has a three-dimensional surface texture with projections (8) and depressions (9) arranged in a grid pattern, wherein the coating (3) is located on the main surface (2') having a three-dimensional surface texture.

10. Cleaning sponge (1) as claimed in any one of claims 1 to 9, characterized in that the carrier body (2) has on one of its main surfaces (2') a coating (3) containing abrasive particles (4) and on the opposite main surface (2") a coating (3) containing non-abrasive particles (4).

11. A method for manufacturing a cleaning sponge (1) as claimed in any one of claims 1 to 10, comprising the following steps: - providing a carrier body (2) of a foam material having two opposing main surfaces (2', 2"), - preparing a coating composition by admixing abrasive or non-abrasive particles (4) into a polyurethane resin, wherein the abrasive particles (4) are selected from the group consisting of pumice particles, quartz sand particles, glass particles, corundum particles, particles of calcined bauxite and mixtures thereof, and have a size in the range of 20 µm to 1,000 µm, and wherein the non-abrasive particles (4) are selected from the group consisting of precipitated silica, river sand, desert sand, walnut shell powder and mixtures thereof, and have a size in the range of 20 µm to 1,000 µm, - applying the coating composition to one of the main surfaces (2', 2") of the carrier body (2), and - allowing the coating composition to cure.

12. A method of manufacturing a cleaning sponge (1) as claimed in any one of claims 1 to 10, comprising the following steps: - providing a carrier body (2) of a foam material having two opposing main surfaces (2', 2"), - applying a polyurethane resin to one of the main surfaces (2', 2") of the carrier body (2) to produce a polyurethane resin coating, - distributing abrasive or non-abrasive particles (4) on the polyurethane resin coating, wherein the abrasive particles (4) are selected from the group consisting of pumice particles, quartz sand particles, glass particles, corundum particles, particles of calcined bauxite and mixtures thereof, and have a size in the range of 20 µm to 1,000 µm, and wherein the non-abrasive particles (4) are selected from the group consisting of precipitated silica, river sand, desert sand, walnut shell powder and mixtures thereof, and have a size in the range of 20 µm to 1,000 µm, and - allowing the polyurethane resin to cure.

13. The method according to claim 11 or 12, characterized in that the coating composition which is applied to the carrier body (2) has a viscosity in the range from 5,000 to 12,000 mPas, preferably from 7,000 to 10,000 mPas, or in that the polyurethane resin which is applied to the carrier body (2) has a viscosity in the range from 5,000 to 12,000 or in the range from 1,000 to 5,000 mPas.

14. The method according to any one of claims 11 to 13, characterized in that the polyurethane resin is a 1-component polyurethane resin which cures in air by reaction with atmospheric humidity at 20 to 25°C within two to eight hours.

15. The method according to any one of claims 11 to 14, characterized in that the carrier body (2) consists of a foam material, in particular of a sponge body made of polyurethane, which, after the coating composition or the polyurethane resin has been allowed to cure, is bonded to its uncoated main surface (2', 2") with a sponge body based on cellulose or made of melamine resin to form a composite carrier body.