AU2007216870C1 - Methods and Tool for Maintenance of Hard Surfaces, and a Method for Manufacturing Such a Tool - Google Patents

Description

1 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: HTC Sweden AB Address for Service: CULLEN & CO. Level 26 239 George Street Brisbane Qld 4000 Invention Title: Methods and Tool for Maintenance of Hard Surfaces, and a Method for Manufacturing Such a Tool The following statement is a full description of the invention, including the best method of performing it, known to us: 2 Technical field The present disclosure relates to a method and a tool for maintenance of hard surfaces, primarily concrete (cement), terrazzo and granite floor surfaces, but also 5 marble or limestone surfaces. The disclosure particularly relates to a method and a tool for maintenance which are suitable for use on a regular basis to maintain a polished hard floor surface. In addition, the present disclosure relates to 10 methods for maintenance of hard, smooth surfaces, primarily wood, linoleum, lacquer and vinyl floor surfaces. The disclosure particularly relates to a methods for maintenance which are suitable for use on a daily basis to maintain a shiny, hard, smooth surface, 15 such as a floor surface. Background It is known in connection with cleaning or light polishing of floor surfaces to use a pad in the form of a 20 three-dimensional non-woven web. The pad is usually provided as a circular, disc-shaped body, which is to be disconnectably mounted on a circular carrier plate, which in use is caused to rotate in a plane parallel with the floor surface, such that the pad, when brought into 25 contact with the floor surface, is slightly compressed by the pressure arising between the floor surface and the carrier plate. The carrier plate is usually driven by a motor and may be mounted on a carrier frame, which may be arranged to be pushed or pulled by a walking operator or 30 which may be arranged as a ridable vehicle.

3 Such pads are formed from fibers of an organic material, e.g. polyamide and/or polyester, particularly polyethylene terephtalate. In some cases the fibers also include natural fibers, such as walnut fibers or coconut 5 fibers. The fibers of the pad is interconnected at their mutual points of contact by so-called melt bonding, whereby the fibers are subjected to heat that cause the outer part of the fibers to slightly melt and thereby to 10 bond to each other. Alternatively, or additionally, the fibers may be interconnected at their mutual points of contact by the pad being impregnated with a polymer resin, hereinafter referred to as a "primary binder". 15 Production of this type of non-woven pads is well known from e.g. US-A-3,537,121, US-A-4,893,439, EP-A-0 397 374, GB-A-1 348 526 and EP-B-0 562 919, and thus does not need to be further elaborated on herein. US-A-3,537,121 discloses pads for polishing surfaces 20 of aluminum, plastic, wax and similar surfaces. US-A 3,537,121 also discloses production of such pads. In US A-3,537,121 a binder mixed with abrasive particles is applied to the pad by passing the pad between a pair of squeeze rolls, one of which is partially immersed in a 25 container for a mixture of binder resin and abrasive particles, after which the pad is allowed to cure or dry. Thus, in US-A-3,537,121 a pad is provided, which is entirely impregnated by the binder and abrasive particles. 30 US-A-4,893,439 discloses a pad for polishing floor surfaces or aluminum. The pad consists of fibers of organic material and constitutes a lofty open non-woven structure, and contains a binder binding abrasive 4 particles to the fibers. The pad shown in US-A-4,893,493 has larger voids than that shown in US-A-3,537,121, and thereby has an improved ability to absorb dirt, so that it can be used for a longer period. Also the pad 5 disclosed in US-A-4,893,493 is entirely impregnated by binder and abrasive particles. EP-A-0 397 374 discloses a pad for floor polishing machines, which also is entirely impregnated by binder and abrasive particles. 10 Pads of the above type are frequently used for so called "burnishing", i.e. dry polishing (often on a daily basis) of very lightly worn surfaces at high speed (1500 3000 rpm) and relatively low pressure, with a view to restoring a polished surface. This type of treatment is 15 commonly used for both vinyl and marble floorings. Pads suitable for this purpose are available from 3M@ under the designation "3MTm Floor Pads", and provide no or little effect on very hard floor surfaces, such as terrazzo or concrete, which have been subject to wear for 20 a longer period of time. EP-B-0 562 919 discloses a non-woven pad of polymer fiber, which is entirely impregnated by a binder comprising a mixture of curable plastic resin and abrasive particles having a particle size of 0,1-30 pm. 25 As examples of curable resins are mentioned phenol resin, acrylic resins, melamine resin and urea resin. Diamond is mentioned as one among several other examples of plausible abrasive particles. However, according to EP-B 0 562 919, the pad disclosed therein is suitable for 30 treatment of marble floor surfaces, and only in combination with crystallization chemicals, which means that treatment must be made in the presence of liquid containing a salt-forming acid.

5 The pad in EP-B-0 562 919 is also provided by passing a non-woven pad through a nip between two squeeze rolls, one of which being partially immersed in a binder/abrasive particles mixture, such that the binder 5 and abrasive particles, via the surface of the cylinder is distributed in the pad. Since the pad disclosed in EP-B-0 562 919 is to be used in the presence of crystallization chemicals, the method described in EP-B-0 562 919 actually constitutes a 10 vitrification method, used with a view to improving the stain resistance and durability of a marble floor. This method is not suitable for daily maintenance purposes, since it involves use of special crystallization chemi cals, including acids, which are to react with calcium 15 present in the floor surface to form insoluble calcium salts. Such a method is typically used once in connection with the initial preparation of the polished marble floor, and thereafter at intervals of 6-12 months. The method described in EP-B-0 562 919 is thus too compli 20 cated for being used on a daily basis. Pads of the type referred to in EP-B-0 562 919 are sold by 3M@ under the designations "3M 5200 Brown Stone Renew Pad" and "3MTm 4000 Grey Stone Polish Pad", and are used for treating marble in the presence of crystall 25 ization chemicals and at relatively low speeds (below 250 rpm). The need for crystallization chemicals, and other surface-improving agents, makes the polishing work more complicated, since the chemicals are to be applied to the 30 surface, possibly followed by removal of excess chemicals, which also contribute to making the polishing work more time consuming. Handling and application of the chemicals also constitute a potential hazard to the 6 environment in general and to the work environment in particular. It is also known to provide a polished stone or concrete surface by using tools comprising grinding or 5 polishing elements made from a plastic resin mixed with abrasive particles, i.a. diamond particles. Since such elements are fixedly mounted on a usually rotating plate, they do not have the ability to compensate for unevenness in the floor, which may lead to uneven treatment of the 10 floor surface, or to scratching or staining of the floor surface in case such an element is to contact the surface at an excess pressure. Yet another problem is that debris, such as grains of sand, small stones or metal may get stuck in or near the elements and cause scratching of 15 the floor surface. Finally, this type of tools require special machinery capable of applying a higher pressure to the contact surface between the tool and the floor surface. W003/075734 discloses a disc-shaped device for 20 cleaning purposes, comprising a nylon scouring material, which is arranged on a rigid disc, whereby grinding elements containing industrial diamonds are placed in recesses in the active scouring surface. A disadvantage with the device disclosed in W003/075734 is that it does 25 not eliminate the risk of debris getting stuck in or near the grinding elements. Yet another disadvantage is that this tool is complex and therefore more prone to breaking and more difficult and expensive to manufacture. Hence, there is a need for an improved and simpli 30 fied method and tool for daily maintenance of hard surfaces. Preferably, the method should be simple to use, e.g. by persons who do not have specialist training in floor surface preparation, and the method should be 7 usable with conventional floor surfacing equipment, e.g. burnishing machines, etc. Also, the tools should be easy to manufacture, not too expensive and durable. 5 Summary of the Invention It is an object to provide an improved technique, which wholly or partially eliminate the problems with the prior art methods and pads. In particular, it is an object to provide a method of treating a hard surface 10 which is more easy to use and which provides a comparable or better result than the prior art methods. In particular, it is an object to provide a method that is suitable for hard, smooth stone or stone-like surfaces. An additional object is to provide a method of 15 polishing, cleaning or otherwise maintaining hard, smooth and preferably glossy surfaces, in particular floor surfaces, with an eliminated or reduced need for surface improving or cleaning chemicals. The invention is based on the idea that abrasive 20 particles in the form of diamond particles provide a polishing effect which is vastly superior to that achievable with those abrasive particles used in the examples shown in e.g. EP-B-0 562 919, and that this polishing effect is so superior as to eliminate the need 25 for crystallization chemicals and other surface-improving agents. The invention is defined by the appended independent claims. Embodiments are set forth in the dependent claims and in the following description and drawings. 30 According to a first aspect, there is provided a method for maintaining a hard, smooth surface, the sur face comprising a material selected from a group consist ing of wood, polymer material, lacquer and linoleum, the 8 method comprising treatment of the surface with a flex ible pad, in the presence of abrasive particles, bonded to the pad, on a contact surface between the pad and the hard surface. The abrasive particles comprise diamond 5 particles. The treatment is performed using a pad comprising an open, lofty, three dimensional non-woven web of fibers. The combination of a flexible pad and diamond particles provides compensation for unevenness in the 10 surface, and distributes the pressure applied to the pad evenly. Also, this combination, through the flexibility of the pad, considerably reduces the risk of the diamonds scratching the surface. Using diamond particles as abrasive particles when 15 polishing hard, smooth surfaces provides an effect equal to or better than use of conventional abrasive particles, both in wet and dry conditions. In particular, the use of diamonds enables the surface-improving agent to be abol ished, thereby eliminating its handling. 20 The treatment may be performed substantially in the absence of liquid on the contact surface, i.e. under substantially dry conditions; or in the presence of water on the contact surface, i.e. under wet conditions. In particular, the treatment may be performed in the 25 presence of water and a cleaning agent on the contact surface, thereby making it combine excellently with the daily maintenance/cleaning operations. In one embodiment, the abrasive particles are bonded to the pad by means of a secondary binder. Hence, no 30 abrasives need to be added when treating the floor. Specifically, the abrasive particles may be bonded to the pad only in the vicinity of the contact surface. This is advantageous, since the abrasive particles present in the 9 parts of the pad that are not in contact with the hard surface do not fulfill any function and therefore can be seen as a waste. The treatment may be performed using a pad having 5 diamond particles of an average diameter of 0,1 to 30 pm, preferably between 0,1 and 15 pm and most preferably between 2 and 15 pm. The treatment may be performed using a pad having diamond particles comprising at least one of natural 10 diamond particles, industrial diamond particles and coated diamond particles. The pad may have a density of less than 40 kg/m 3 , preferably 20-35 kg/m. Thus, the pad comprises a relatively large amount of voids, into which dust, debris 15 and particles may migrate during the treatment. Thus, dust is to a large extent contained in the pad rather than being distributed in the area where the treatment is taking place, eliminating the need for additional dust collecting equipment. Also, by allowing debris to migrate 20 into the pad, the risk for scratching of the surface is reduced. The hard, smooth surface may be a floor surface. The pad, while in contact with the hard surface, may be caused to move in relation to the hard surface. 25 The pad, while in contact with the hard surface, may be caused to rotate at a rotational speed of 50-3000 rpm, preferably of 100-1500 rpm. In one embodiment, the surface may comprise a polymer material, such as polyvinyl and the treatment may 30 be performed using a pad having diamond particles of an average diameter of between 0,1 and 15 pm and most preferably between 3 and 12 pm.

10 In another embodiment, the surface comprises linoleum, and the treatment is performed using a pad having diamond particles of an average diameter of between 0,1 and 15 pm, preferably between 3 and 12 pm and 5 most preferably between 3 and 6 pm. In yet another embodiment the treatment is performed using a pad having diamond particles of an average diameter of between 0,1 and 15 pm, preferably between 3 and 12 pm and most preferably between 3 and 6 pm. 10 The hard, smooth surface may have a hardness less than about 3 mohs, preferably less than about 2 mohs and most preferably less than about 1 moh. The treatment may be performed in the absence of an effective amount of surface-improving agents on the 15 contact surface. The term "surface-improving agents" is understood to include substances that are added when treating the surface to interact with the surface to render the surface more glossy. As examples of surface-improving 20 agents can be mentioned, waxes, oils, resins, varnish and similar products. Soap, detergents and similar products that are added for cleaning purposes are not considered "surface-improving agents". The term "effective amount" is understood as an 25 amount that is sufficient to achieve a measurable gloss improvement as compared to the same treatment using a liquid containing no surface-improving agent at all. The definition of an effective amount may vary in relation to at what interval the treatment is being 30 performed. Hence, for an ad-hoc treatment, i.e. a single occasion, a much higher amount may be needed to achieve a surface-improving effect, than if the treatment was performed with an interval of one or a few days, or even 11 a week. The amount may need to be adjusted to apply to the respective type of surface-improving agent chosen and to the type of surface that is being treated. According to another aspect, there is provided a 5 method for maintaining a hard, smooth surface, the surface comprising a material selected from a group consisting of a gelcoat, glass and automotive enamel, the method comprising treatment of the surface with a flexible pad, in the presence of abrasive particles, 10 bonded to the pad, on a contact surface between the pad and the hard surface. The abrasive particles comprises diamond particles. The treatment is performed in the absence of an effective amount of surface-improving agents on the contact surface, and the treatment is 15 performed using a pad comprising an open, lofty, three dimensional non-woven web of fibers. Furthermore, there is provided a method for treating or maintaining a hard surface comprising a stone or stone-like material, the method comprising treatment of 20 the surface with a flexible pad, in the presence of abrasive particles, bonded to the pad, on a contact surface between the pad and the hard surface, wherein the abrasive particles comprise diamond particles, and the treatment is performed in the absence of an effective 25 amount of crystallization agent on the contact surface. The term "diamond" is understood to include natural diamond as well as synthetic diamond, and diamond particles being coated with any suitable coating, e.g. silver. 30 The term "effective amount" is understood as an amount that is sufficient to achieve a measurable gloss improvement as compared to the same treatment using a liquid containing no crystallization agent at all.

12 Amounts known to be effective are about 1-2 liters of crystallization agent (comprising 2-30 % by weight of e.g. magnesium hexafluorosilicate) per 50 m 2 of floor surface for a single treatment operation. Hence, amounts 5 known to be effective on an ad-hoc basis range from about 0,4 g of magnesium hexafluorosilicate per m 2 floor surface. However, diluted crystallization agent, e.g. at a ratio of 1:100 is also known to be effective when used repeatedly, e.g. in connection with daily or weekly 10 maintenance. Hence, amounts known to be effective for maintenance on a regular basis range from about 0,004 g of magnesium hexafluorosilicate per m 2 floor surface. It is understood that there are other types of crystall ization agents, e.g. zinc hexafluorosilicate, hydro 15 fluoric acid and oxalic acid. The values given above may thus need to be adjusted to apply to the respective type of crystallization agent chosen. The combination of a flexible pad and diamond particles provides compensation for unevenness in the 20 surface, and distributes the pressure applied to the pad evenly. Also, this combination, through the flexibility of the pad, considerably reduces the risk of the diamonds scratching the surface. Using diamond particles as abrasive particles when 25 polishing hard stone surfaces provides an effect equal to or better than use of conventional abrasive particles, both in wet and dry conditions. In particular, the use of diamonds enables the crystallization agent to be abol ished, thereby eliminating its handling. 30 The treatment may be performed substantially in the absence of liquid on the contact surface, i.e. during substantially dry conditions; or in the presence of water on the contact surface, i.e. during wet conditions. In 13 particular, the treatment may be performed in the presence of water and a cleaning agent on the contact surface, thereby making it combine excellently with the daily maintenance/cleaning operations. 5 In one embodiment, the abrasive particles are bonded to the pad by means of a secondary binder. Hence, no abrasives need to be added when treating the floor. Specifically, the abrasive particles may be bonded to the pad only in the vicinity of the contact surface. This is 10 advantageous, since the abrasive particles present in the parts of the pad that are not in contact with the hard surface do not fulfill any function and therefore can be seen as a waste. The abrasive particles may have an average diameter 15 of 0,1 to 30 pm, preferably between 0,1 and 15 pm and most preferably between 10 and 15 pm. The abrasive particles may comprise at least one of natural diamond particles, industrial diamond particles and coated diamond particles. 20 The treatment may be performed using a pad having diamond particles of an average diameter of 0,1 to 30 pm, preferably between 0,1 and 15 pm and most preferably between 5 and 15 pm. In one embodiment, the pad that is used comprises an 25 open, lofty, three dimensional non-woven web of fibers. Such webs are available at a relatively low cost and in standard sized adapted for the existing surfacing machines. The pad may have a density of less than 40 kg/M 3 , 30 preferably 20-35 kg/M 3 . Thus, the pad comprises a relatively large amount of voids, into which dust, debris and particles may migrate during the treatment. Thus, dust is to a large extent contained in the pad rather 14 than being distributed in the area where the treatment is taking place, eliminating the need for additional dust collecting equipment. Also, by allowing debris to migrate into the pad, the risk for scratching of the surface is 5 reduced. The method is particularly suitable for use on a floor surface. The method is particularly applicable where the surface is a stone or stone-like material having a 10 hardness of about 5 moh or more, preferably 6-7 moh. Examples of such surfaces are concrete, terrazzo, granite etc. The pad, while in contact with the hard surface, may be caused to rotate at a rotational speed of 50-3000 rpm, 15 preferably of 100-1500 rpm. The treatment may be performed on a substantially regular basis, such as daily, weekly or monthly. Furthermore, there is provided a tool for treating a hard surface, the tool comprising a flexible pad having 20 an active treatment surface presenting abrasive particles bonded to the pad. The pad presents a first portion wherein said abrasive particles are present in a first concentration, and a second portion having a second, lower concentration of said abrasive particles, said 25 abrasive particles comprising diamond particles. In one embodiment, the second portion is substantially free from diamond particles. Since the abrasive particles present in the parts of the pad that are not in contact with the hard surface do 30 not fulfill any function, pads according to this disclosure can be manufactured at a lower cost. The flexibility of the pad eliminates or reduces the harmful effects that diamond abrasive particles could 15 otherwise have on the hard surface. Hence, the tool may be used for any hard surface, such as surfaces of wood, laminate, marble, granite, concrete, terrazzo, etc. However, the tool is particularly effective for hard 5 stone or stone-like surfaces, such as granite, concrete, terrazzo, etc. In one embodiment, the pad consists of a disc-shaped body having a thickness and a first surface, wherein said abrasive particles are present on said first surface and 10 down to a depth from said first surface, which depth is less than said thickness, such that said first portion is at said first surface and said second portion is at a second surface, opposite said first surface. By leaving the second surface free from abrasive material and 15 binder, the attachment of the pad to a Velcro hook connector on a carrier plate is facilitated. In a second embodiment, the pad consists of a disc shaped body having a thickness and a first surface, wherein said abrasive particles are present over less 20 than the entire first surface, such that said first and second portions are situated adjacent each other at said first surface. This second embodiment facilitates migra tion of dust and debris into the pad. In one embodiment, the pad comprises an open, lofty, 25 three dimensional non-woven web, including a plurality of fibers, which are adhered to each other at their points of mutual contact. The abrasive particles may be bonded to the fibers of the pad by a secondary binder. Hence, the bonding of 30 the fibers of the pad does not in any way need to be negatively affected by the fact that the abrasive particles are only present at the contact surface.

16 As non-limiting examples, the secondary binder may be selected from a group consisting of phenol resin, melamine resin, urea resin and epoxy resin. In one embodiment, the secondary binder forms a 5 plurality of distinct droplets having a maximum diameter which is smaller than an average length between two points of mutual contact of a fiber. Thus, the fibers are not entirely coated by the binder resin, facilitating further the migration of dust and debris into the pad. 10 The abrasive particles may comprise diamond particles having an average diameter of 0,1 to 30 pm, preferably between 0,1 and 15 pm and most preferably between 5 and 15 pm. The pad may further comprise second abrasive 15 particles selected from a group consisting of graphite, tin oxide, silicon carbide and aluminum oxide. The pad is preferably provided in the shape of a circular disc having a diameter between 30 and 100 cm and an uncompressed thickness between 1 and 5 cm. 20 Furthermore, there is provided a method for manu facturing a pad for treating a hard surface. The method comprises: providing a pad, and applying, on a first sur face of the pad, a mixture of a binder and abrasive particles including diamond, such that said pad presents 25 a first portion wherein said abrasive particles are present in a first concentration and a second portion, having a second, lower concentration of said abrasive particles. In one embodiment, the second portion is substantially free from said abrasive particles. The 30 abrasive particles may be provided to the first surface by spraying, rolling or dipping.

17 According to a first preferred embodiment of the invention, there is provided a method for maintaining a hard, smooth surface, the surface comprising a material selected from a 5 group consisting of wood, polymer material, lacquer and linoleum, the method comprising treatment of the surface with a flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, in the presence of 10 abrasive particles, bonded to the pad, on a contact surface between the pad and the hard surface, wherein the abrasive particles comprise diamond particles. According to a second preferred embodiment of the 15 invention, there is provided a method for maintaining a hard, smooth surface, the surface comprising a material selected from a group consisting of a gelcoat, glass and automotive enamel, 20 the method comprising treatment of the surface with a flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, in the presence of abrasive particles, bonded to the pad, on a contact surface between the pad and the hard surface, 25 wherein the abrasive particles comprise diamond particles, wherein the treatment is performed in the absence of an effective amount of surface-improving agents on the contact surface. 30 According to a third preferred embodiment of the invention, there is provided a method for maintaining a hard floor surface comprising a stone or stone-like material, the method comprising treatment of the surface 18 with a flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, in the presence of abrasive particles, bonded to the pad, on a contact surface between the pad and the hard surface, wherein: 5 the abrasive particles comprise diamond particles, and the treatment is performed in the absence of an effective amount of crystallization agent on the contact surface. According to a fourth preferred embodiment of the 10 invention, there is provided a tool for treating a hard surface, the tool comprising a flexible pad, comprising an open, lofty, three dimensional non-woven web of fibers, having an active treatment surface presenting abrasive particles bonded to the pad, wherein the pad 15 presents a first portion wherein said abrasive particles are present in a first concentration, and a second portion having a second, lower concentration of said abrasive particles, said abrasive particles comprising diamond particles. 20 According to a fifth preferred embodiment of the invention, there is provided a floor surfacing machine, comprising a tool according to the fourth embodiment. According to a sixth preferred embodiment of the invention, there is provided a method for manufacturing a 25 tool for treating a hard surface, the method comprising: providing a pad comprising an open, lofty, three dimensional non-woven web of fibers, and applying, on a first surface of the pad, a mixture of a binder and abrasive particles including diamond, such 30 that said pad presents a first portion wherein said abrasive particles are present in a first concentration and a second portion, having a second, lower concentration of said abrasive particles.

18a Definitions of the specific embodiments of the invention as claimed herein follow. According to a first embodiment of the invention, there is provided a hard floor surface treating tool, the tool 5 comprising a flexible pad having an active treatment surface presenting abrasive particles bonded to the pad, wherein the pad presents a first portion wherein said abrasive particles are present in a first concentration, and a second portion having a second, lower concentration of said abrasive 10 particles, wherein the pad comprises an open, lofty, three dimensional non-woven web, including a plurality of fibers, which are adhered to each other at their points of mutual contact, and wherein the pad presents a standard size adapted for an existing floor surfacing machine, characterised in that 15 said abrasive particles comprise diamond particles. According to a second embodiment of the invention, there is provided a floor surfacing machine, comprising a tool according to the first embodiment of the invention. According to a third embodiment of the invention, there 20 is provided a system for maintaining a hard floor surface comprising stone or stone-like material, the system comprising: a first flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, and presenting an active 25 treatment surface presenting first abrasive particles bonded to the pad, the first abrasive particles comprising diamond particles having a first average diameter; and a second flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, and presenting an active 30 treatment surface presenting second abrasive particles bonded to the pad, the second abrasive particles comprising diamond particles having a second average diameter, 18b wherein the first flexible pad presents a first portion wherein the diamond particles are present in a first concentration, and a second portion where the diamond particles are present in a second, lower concentration, 5 wherein the second flexible pad presents a first portion wherein the diamond particles are present in a first concentration, and a second portion wherein the diamond particles are present in a second, lower concentration, and wherein the first average diameter is greater than the 10 second average diameter. [Text continues on page 19.] 19 Brief description of the drawings Figs la-lb show a pad according to a first embodiment. 5 Figs 2a-2b show a pad according to a second embodiment. Figs 3a-3b show enlarged photographs of a pad according to the present disclosure, before and after the binder and abrasive particles have been applied. 10 Fig. 4a-4b show a diagram of a pad according to the first embodiment, and an enlargement of a portion of the pad. Fig. 5 is a sectional view of a floor surfacing machine on which a pad according to the disclosure is 15 mounted. Description of embodiments The description will first focus on a tool suitable for use in the method for maintenance of hard surfaces, 20 subsequently on the method for manufacturing the tool, and finally on the use of the tool for maintenance of a hard surface. Referring to Fig. la, there is shown a pad 1 made up from an open, lofty three dimensional non-woven web of 25 fibers 2. A first surface of the pad 1 has a portion Pl presenting abrasive particles bonded to the web by means of a secondary binder, i.e. a binder having as a main purpose to bond fibers to the web. The pad 1 is circular in shape. 30 Referring to Fig. lb, a cross section along the line Sl-S2 in Fig. la is shown. As is indicated in Fig. lb, the portion Pl presenting the abrasive particles is present at the first surface A and to a depth D, which is 20 less than the thickness T of the pad 1. Hence, at the second surface B there is a portion P2, which is substantially free from the abrasive particles and the secondary binder. 5 When referring to "portions", it is to be understood as a portions of the macrostructure of the pad 1 and not portions of the individual fibers. Referring to Figs 2a and 2b, there is shown a similar pad 1, the difference being that there is a 10 portion P2' also at the first surface A, which portion P2' is substantially free from the abrasive particles and the secondary binder. In both embodiments, the abrasive particles are present throughout the secondary binder, and the fibers 15 are bonded to each other by a primary binder and/or by being melt-bonded. A description of the preparation of a pad 1 according to the embodiment discussed with reference to Figs la and lb will now be given. 20 As a starting material, circular, disc shaped Glit/Microtron@ Tan Floor Polishing Pad having a diameter of 20 inches (51 cm), a thickness of 28 mm and a weight of 157 grams was used. Such pads are available from Glit/Microtron, Wrens, GA, USA. The starting density of 25 the pad was thereby 27 kg/m 3 . Fig. 3a is a microscope photograph showing the pad prior to application of the polymer resin/abrasive particles. From Fig. 3a, it can be seen that the fibers constituting the pad are held together at their points 10 of mutual contact by a 30 primary polymer resin. The pad is flexible and resilient and comprises polyester and nylon fibers. A homogenous polymer resin mixture was prepared, consisting of 200 g PA resin 52-68 phenol resin (availa- 21 ble from Perstorp AB, Perstorp, Sweden), 100 g of T-ROD@ ethanol (available from Alfort & Cronholm AB, Bromma, Sweden) and 20 g of LANDS LS600F 4-8 pm diamond particles (available from Lands Superabrasives, Co., New York, NY, 5 USA). Just before application of the mixture, 60 g of 65% p-toluene sulfonic acid (PTS) was added as a hardener. The resin mixture was sprayed onto a first one A of the surfaces of the polishing pad, using a standard-type compressed air spray gun (normally used for spraying 10 paint). The pad with the uncured resin thereafter weighed 173 grams. Subsequently, the pad was placed in a hot air oven at approximately 1200C for approximately 20 minutes. The pad has now assumed the appearance that can be seen from Fig. 3b, which is a microscope photograph. 15 Globules or droplets 11 of the resin/particle mixture are formed along each fiber, also between the fibers' points of mutual contact. The droplets are so distributed that the fibers to which they are adhered are not entirely covered. A more clear illustration of this is found in 20 Figs 4a-4b, which show a pad as described above with reference to Figs la-lb, and an enlargement of a portion of that pad (Fig. 4b), wherein droplets 11 of binder/particle mixture are attached to the fibers. In order to evaluate the performance of the pad 25 produced as described above, comparative tests were carried out in order to evaluate two different 20 inch (51 cm) pads, prepared as described above: a first one, referred to as "yellow", having 7-12 pm silver coated diamond particles, and a second one, referred to as 30 "green", having 3-6 pm normal diamond particles. As a reference, two different commercially available pads were used: a 20 inch (51 cm) 3M Tm 5200 Brown Stone Renew Pad 22 and a 20 inch (51 cm) 3M M 4000 Grey Stone Polish Pad were used, both available from 3M, St. Paul, MN, USA. The tests were made on two different surface types: Kolmirden marble (marble from the KolmArden area outside 5 Norrkoping, Sweden) and K40 concrete. Each test was 2 carried out on a surface of about 1 m , using a Coor & Kleever Crystallizer 1250KG floor surfacing machine (available from Coor & Kleever, S.A., Barcelona, Spain) having a single carrier plate adapted for receiving a 20 10 inch floor pad and rotating at about 175 rpm. The test 2 included polishing the surface for about 1 minute/m . The surface gloss was measured at several spots on the area before and after each treatment using a Sanwal/Cenma IG 310 Glosschecker. The gloss value in the tables below 15 constitute the average value for each area. High gloss is rated 80-900. Semi gloss is rated 50-75'. Satin is rated 30-45'. Rubbed effect is rated 20-25'. Flat sheen is rated 5-15o. Each surface was tested both dry and using water as 20 a lubricant. Additionally, the concrete surface was tested using Coor Rosa/K-2 crystallizer (available from Coor & Kleever S.A., Barcelona, Spain) as lubricant, i.e. the crystallization chemical mentioned in EP-B-0 562 919 as comprising magnesium hexafluourosilicate as crystall 25 ization agent. When testing the 3MTm pads, each surface portion was first treated with the brown pad and subsequently with the gray pad. Table 1: Tests performed with water as lubricant on 30 Kolmirden marble Pad Brown Gray Green Initial gloss 17 17 10 Liquid Water Water Water 23 Final gloss 17 35 30 Table 2: Tests performed without lubricant on Kolmerden marble Pad Brown Gray Green Initial gloss 20 25 28 Liquid No No No Final gloss 25 30 50 From tables 1 and 2, it can be concluded that on marble, which is a relatively soft stone having a 5 hardness of about 3-5 moh, and using water as a lubri cant, the 3MTm pad combination (brown and gray) provide a slightly better effect, although both the gray and the green pads achieved values falling within the "satin" range. However, during dry conditions, the green pad 10 achieved a remarkable improvement, reaching the semi gloss range. Table 3: Tests performed with water as lubricant on K40 concrete Pad Brown Gray Yellow Green Initial gloss 30 29 24 35 Liquid Water Water Water Water Final gloss 29 29 35 46 15 Table 4: Tests performed without lubricant on K40 concrete Pad Brown Gray Yellow Green Initial gloss 29 34 30 48 Liquid No No No No Final gloss 34 35 48 58 From Tables 3 and 4, it is noted that in wet conditions and on K40 concrete, having a hardness of about 6-7 moh, the combination of brown and gray pads did 20 not provide any measurable improvement at all, whereas 24 the combination of yellow and green pads provided a distinct improvement. In dry conditions, a small improve ment was noted for the surface treated with the combi nation of brown and gray pads, whereas a major improve 5 ment was noted for the surface treated by the combination of yellow and green pads. Table 5: Tests performed with Coor Rosa/K-2 crystallizer as lubricant on K40 concrete Pad Gray Green Initial gloss 41 35 Liquid VMC-Pink VMC-Pink Final gloss 45 51 From table 5, it is noted that some effect is 10 achievable with a gray pad using Coor Rosa/K-2 crystallizer as lubricant on K40 concrete, and that a somewhat better effect is achievable with the green pad using Coor Rosa/K-2 crystallizer as lubricant. All in all, it is concluded that the pad according 15 to the present disclosure provides a noticeable improve ment as compared with the prior art. The improvement is particularly noticeable during dry conditions and on concrete. Fig. 5 is a sectional view of a floor surfacing 20 machine 20 on which a pad 1 according to the present disclosure is mounted so as to define a contact surface 9 with the hard surface 8, which in this example is a floor surface. The pad 1 is mounted on a driven, rotatable carrier plate 4, which is typically journalled in 25 bearings and thus rotatable relative to a machine body 5, on which a motor unit 6 is arranged. In this embodiment, the machine has a handle 7, and is thus adapted for being held/pushed/pulled by a walking operator. It is recognized that in other embodiments the floor surfacing 25 machine 20 may be e.g. a ridable vehicle fitted with a carrier plate 4 that is adapted for receiving the pad 1. The pad 1 and method described above can be used for everyday cleaning/maintenance of polished hard surfaces, 5 such as stone, concrete or terrazzo floor surfaces using a floor surfacing machine such as a scrubber/dryer combination machine, e.g. the Nilfisk CR1300; a single disc floor maintenance machines (low speed or high speed), e.g. the Nilfisk 510B or 545; a burnisher, e.g. 10 the Nilfisk SDH5120, BHS5120 or BHS7014, all of which are available from Nilfisk-Advance, Stockholm, Sweden. The treatment of the floor surface is typically performed by causing the pad, when in contact with the floor surface, to rotate in a plane parallel with the 15 floor surface. Typical rotational speeds are from 50 rpm to 3000 rpm. However, lower or higher rotational speeds are not excluded. As is clear from the above, a first embodiment of the pad according to the present disclosure comprises an 20 open, lofty, three dimensional non-woven web, including a plurality of fibers, which are adhered to each other at their points of mutual contact by means of a primary binder, and in which abrasive particles are mixed with a secondary binder and applied only to a first surface of 25 the pad, such that the pad is only partially impregnated by the binder/particle mixture. Alternatively, or additionally, the fibers may be melt-bonded to each other. In a second embodiment of the pad, binder/particle 30 mixture is only applied to parts of said first surface. This can be achieved by masking those parts of the surface to which the binder/particle mixture should not be applied.

26 In a third embodiment, the pad is entirely impregnated with the binder/particle mixture, e.g. by using such squeeze rollers as are described in EP-B-0 562 919. In a variant of this embodiment, a relatively thin 5 impregnated woven or non-woven pad is attached to a thicker carrier pad in order to provide the flexibility. According to variants of this embodiment, a substantially two-dimensional woven or non-woven web is attached to a thicker carrier pad. 10 In a fourth embodiment, a three dimensionally woven or knitted pad may be used, whereby the binder/particle mixture is applied as described above. In a fifth embodiment, the abrasive particles are present in the material of the pad. In a first alter 15 native, the pad is a non-woven fiber pad substantially as described above, with the diamond particles included in the fiber material. In a second alternative, the pad is a polymer foam pad with the diamond particles included in the foamed polymer material. 20 In a sixth embodiment, the pad is a polymer foam pad, to a surface of which a binder/particle mixture is applied as described above. The present disclosure is not limited to the use of phenol resin. Other examples of suitable resins are 25 melamine, urea, epoxy and polyester resins. Furthermore, the hardener may be selected from any hardener suitable for the type of resin selected. Also it is possible not to include the hardener, e.g. by allowing the pad to cure at a higher temperature and/or for a 30 longer period of time. Also, the solvent (ethanol was used in the example) is provided merely to reduce the viscosity of the mixture and thereby to facilitate spraying thereof. Any suitable 27 solvent may be used, and the solvent may also be excluded, provided that the method of application so allows. The abrasive particles preferably include diamond. 5 However, floor treatment pads may be produced according to the principles set forth above using other types of abrasive particles, or combinations thereof, as well, e.g. those mentioned in EP-B-0 562 919. In particular silver coated diamond particles have proven to provide 10 good results as well. Naturally, the diamond particles may be combined with other types of abrasive particles. It is understood that the pad 1 having secondary binder and abrasive particles as described above may be attached to a disc or plate having an arbitrary connector 15 for being connected to a carrier plate of the surfacing machine, or that the pad may be directly connectable to the surfacing machine by means of a Velcro-type hook arrangement provided on the carrier plate, the hooks of which engage the fibers of the pad 1. Hence, the 20 maintenance tool may be composed of the pad with the primary binder, the secondary binder and the abrasive particles, possibly with the addition of dyes or printed areas providing information on the type of pad, manufacturer, trademark etc. 25 Alternatively, or additionally, the pad may be provided with a backing layer. Further tests were performed using applicant's yellow and green pads, described above, as well another pad, referred to as "white", having 15-30 pm diamond 30 particles, but otherwise corresponding to the yellow and green pads described above. As a reference, a 3M® 5100 Red Buffer Pad, available from 3M, St. Paul, MN, USA, was used.

28 In a first additional test, the applicant's pads were tested on an oiled oak parquet surface. Gloss values of the floor was measured, before and after treatment, at five spaced apart points using the gloss meter referred 5 to above, whereby an average gloss value was calculated after processing with each pad type. The results are shown in Table 6. Table 6: dry polishing of oiled oak parquet Pad 3M® red White Yellow Green Initial gloss 6.0 6.0 6.0 6.0 Liquid No No No No Final gloss 20.2 17.0 26.0 31.4 From Table 6, it can be seen that a gloss improve 10 ment from a silk matt surface (6.0) is achievable, in particular when using the yellow and white pads, which both provide a very shiny surface. The white pad provided a shiny surface, whereas the 3M® red pad provided a shiny, though somewhat blotchy surface. It was noticed 15 that the white, yellow and green pads provided a very clean floor. In a second additional test, the applicant's pads were tested for wet polishing of an oiled oak parquet surface. Gloss values of the floor was measured, before 20 and after treatment, at five spaced apart points using the gloss meter referred to above, whereby an average gloss value was calculated after processing with each pad type. The results are shown in Table 7. Table 7: dry polishing of oiled oak parquet Pad White Yellow Green Green Initial gloss 6.8 6.8 6.8 6.8 Liquid Water Water Water No Final gloss 0.0 0.0 0.0 22,8 29 From Table 7, it can be seen that starting from a silk matt surface, the white and yellow pads provided an entirely matt surface, with some grinding residue being noticeable in the water. The green pad, on the other hand 5 provided a matt, entirely smooth surface. Dry polishing with the green pad provided a shiny and clean surface, entirely free from oil film. It was noticed that the white, yellow and green pads provided a very clean floor. It was also noted that dry polishing of the flooring 10 using the white, yellow or green pads subsequent to the wet polishing, provided gloss values similar to those of Table 6. Hence, it is concluded that the pad disclosed herein may be used for grinding and/or polishing wood surfaces, 15 such as wood floor surfaces, deck surfaces (on e.g. patios or boats), wall surfaces, interior moldings, doors, baseboards etc. In a third additional test, the applicant's pads were tested for dry polishing of an Amtico@ vinyl tile 20 flooring, available from Amtico International, Coventry, UK, processed with flooring wax to a shiny finish. Initially, the surface had multiple scuff marks. Gloss values of the floor was measured, before and after treatment, at five spaced apart points using the gloss 25 meter referred to above, whereby an average gloss value was calculated after processing with each pad type. The results are shown in Table 8. Table 8: dry polishing of Amtico@ vinyl flooring Pad Gloss Comment None 24.8 Shiny surface, multiple scuff marks 3M@ red 24.8 Shiny surface, scuff marks remaining White 16.4 Clean, matt surface, no scuff marks Yellow 19.4 Clean surface, no scuff marks Green 24.4 Very shiny, clean surface 30 From Table 8 it is noted that the 3M@ red pad, while maintaining the shiny floor surface, did not remove all scuff marks. The white pad removed the scuff marks, at a loss in shininess. With the yellow pad, a more shiny 5 surface was obtainable, with all scuff marks being removed. The green pad provided a surface having practically the same shine as the initial surface, although the scuff marks were entirely removed. It was noticed that the white, yellow and green pads provided a 10 very clean floor. In a fourth additional test, the applicant's pads were tested for wet polishing of the Amtico@ vinyl tile flooring, processed with flooring wax to a shiny finish. Initially, the surface had multiple scuff marks. Gloss 15 values of the floor was measured, before and after treatment, at five spaced apart points using the gloss meter referred to above, whereby an average gloss value was calculated after processing with each pad type. For reference, dry polishing using the green pad was 20 performed. The results are shown in Table 9. Table 9: wet polishing of Amtico@ vinyl flooring Pad Liquid Gloss Comment None None 24.0 Shiny surface, multiple scuff marks 3M® red Water 24.8 Shiny surface, some scuff marks I remaining White Water 15.2 Clean, matt surface, no scuff marks Yellow Water 19.0 Clean surface, somewhat more shiny Green Water 20.4 Clean surface Green None 26.8 Very shiny, clean surface From Table 9, it is noted that the 3M® red pad once more failed to remove all scuff marks from the floor surface, although providing a shiny surface. The white 25 pad provided a clean, matt surface, whereas the yellow pad provided a clean, slightly more shiny surface. The 31 result from the green pad, when used for wet polishing was moderately better than that of the yellow pad. Once more, the green pad when used in dry conditions provided a very shiny, clean surface. It was noticed that the 5 white, yellow and green pads provided a very clean floor. In a fifth additional test, the applicant's pads were tested for dry polishing of a linoleum floor surface. The initial surface had been treated with flooring wax. Gloss values of the floor was measured, 10 before and after treatment, at five spaced apart points using the gloss meter referred to above, whereby an average gloss value was calculated after processing with each pad type. The results are shown in Table 10. Table 10: dry polishing of linoleum surface Pad Liquid Gloss Comment None None 19.0 3M® red None 21.0 No noticeable change White None 12.8 The surface is matted Yellow None 21.5 The surface is perceived as more shiny than reference Green None 26.3 Very shiny and clean surface 15 From Table 10, it is noted that whereas the white pad provides a matter surface, the 3M® red pad only provides a slight improvement, whereas the surface processed with the yellow pad is perceived as more shiny than the reference surface. The green pad provides a very 20 shiny and clean surface. It was noticed that the white, yellow and green pads provided a very clean floor. In a sixth additional test, the applicant's pads were tested for wet polishing of a linoleum floor surface. The initial surface had been treated with 25 flooring wax. Gloss values of the floor was measured, before and after treatment, at five spaced apart points using the gloss meter referred to above, whereby an 32 average gloss value was calculated after processing with each pad type. The results are shown in Table 11. Table 11: wet polishing of linoleum surface Pad Liquid Gloss Comment None Water 19.0 3M® red Water 7.3 Very matt surface after scouring White Water The polished surface removed by 3.5 scouring Yellow Water The polished surface removed by 7.0 scouring, matt finish maintained Green Water Somewhat more shiny than after 9.8 yellow pad, matt finish From Table 11, it is noted that the 3M@ red pad 5 provides a very matt surface, while the white pad provides a matt surface, and completely removes the polished surface. The yellow pad provides a matt finish, while removing the polished surface. The green pad provides a slightly more shiny finish as compared with 10 the yellow pad. It was noticed that the white, yellow and green pads provided a very clean floor. It was also noted that dry polishing of the flooring using the white, yellow or green pads subsequent to the wet polishing, provided gloss values similar to those of Table 10. 15 Hence, the pad may be used for grinding and/or polishing linoleum and plastic floors, e.g. floors having a surface comprising vinyl, polyurethane, epoxy, acrylic or other plastic material. In particular, the pad is suitable for dry polishing of such surfaces. 20 In a seventh additional test, the applicant's pads were tested for dry polishing of a lacquered parquet floor surface. In this test, an additional pad, termed "Orange" and having diamond particles of 2-4 micron was used. Gloss values of the floor was measured, before and 25 after treatment, at five spaced apart points using the gloss meter referred to above. The results are shown in Table 12.

33 Table 12: polishing of lacquered parquet surface Pad Green Orange Orange Initial gloss 40 40 47-50 Liquid None None None Final gloss 47-51 58-60 56-59 From Table 12, it is noted that the pads can be used for cleaning/polishing lacquered surfaces as well. Using the orange pad provides an additional gloss increase, 5 regardless of whether it is performed on a surface having an initial gloss value of 40 or of 47-50. Hence, it is concluded that the pad disclosed herein may be used for grinding and/or polishing lacquered surfaces, e.g. lacquered wood surfaces, such as wood 10 parquet floor and other lacquered surfaces (on e.g. patios or boats), wall surfaces, interior moldings, doors, baseboards etc. According to another embodiment, the pad may be used for polishing polymer surfaces, e.g. so-called "gelcoat" 15 surfaces, that are found on fiber-reinforced plastic structures, such as boats etc., and which typically comprise resin and optionally pigments. According to yet another embodiment, the pad may be used for grinding and/or polishing glass surfaces, such 20 as e.g. automobile windows/windscreens, in order to remove small scratches etc. According to yet another embodiment, the pad may be used for grinding and/or polishing automobile bodies, and even for polishing painted surfaces on automobile bodies, 25 i.e. automotive enamel. Whereas the methods disclosed herein are suitable for regular treatment or maintenance, they can also be used for ad hoc polishing or grinding treatment.

34 The term "comprise" and variants of the term such as "comprises" or "comprising" are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, 5 unless in the context or usage an exclusive interpretation of the term is required. Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims (24)

1. A hard floor surface treating tool, the tool comprising a flexible pad having an active treatment surface presenting abrasive particles bonded to the pad, wherein the pad presents a 5 first portion wherein said abrasive particles are present in a first concentration, and a second portion having a second, lower concentration of said abrasive particles, wherein the pad comprises an open, lofty, three dimensional non-woven web, including a plurality of fibers, which are adhered to each other .0 at their points of mutual contact, and wherein the pad presents a standard size adapted for an existing floor surfacing machine,characterised in that said abrasive particles comprise diamond particles.

2. The tool as claimed in claim 1, wherein said second portion .5 is substantially free from diamond particles.

3. The tool as claimed in claim 1 or claim 2, wherein the pad comprises a disc-shaped body having a thickness and a first surface, wherein said abrasive particles are present on said first surface and down to a depth from said first surface, which !0 depth is less than said thickness, such that said first portion is at said first surface and said second portion is at a second surface, opposite said first surface.

4. The tool as claimed in any one of claims 1-3, wherein the pad comprises a disc-shaped body having a thickness and a first 25 surface, wherein said abrasive particles are present over less than the entire first surface, such that said first and second portions are situated adjacent each other at said first surface.

5. The tool as claimed in any one of the preceding claims, wherein the abrasive particles are bonded to the material of the 30 pad by a secondary binder. 36

6. The tool as claimed in any one of the preceding claims, wherein the secondary binder comprises at least one of phenol resin, melamine resin, urea resin and epoxy resin.

7. The tool as claimed in any one of the preceding claims, 5 wherein said secondary binder forms a plurality of distinct droplets having a maximum diameter which is smaller than an average length between two points of mutual contact of a fiber.

8. The tool as claimed in any one of the preceding claims, wherein the abrasive particles are present throughout the LO secondary binder.

9. The tool as claimed in any one of the preceding claims, wherein the fibers are bonded to each other by a primary binder and/or by being melt-bonded.

10. The tool as claimed in any one of the preceding claims, L5 further comprising a second abrasive particles selected from a group consisting of graphite, tin oxide, silicon carbide and aluminum oxide.

11. The tool as claimed in any one of the preceding claims, wherein the pad has the shape of a circular disc having a 20 diameter between 30 and 100 cm and an uncompressed thickness between 1 and 5 cm.

12. The tool as claimed in any one of the preceding claims, wherein the abrasive particles comprise diamond particles having an average diameter of 0.1pm to 30pm. 25

13. The tool as claimed in claim 12, wherein the diamond particles have an average diameter of 0.1pm to 15pm.

14. The tool as claimed in claim 12, wherein the diamond particles have an average diameter of 2pm to 4ym.

15. The tool as claimed in claim 12, wherein the diamond 30 particles have an average diameter of 3pm to 8pm. 37

16. The tool as claimed in claim 12, wherein the diamond particles have an average diameter of 5pm to 15pm.

17. The tool as claimed in claim 12, wherein the diamond particles have an average diameter of 7pm to 12pm. 5

18. The tool as claimed in claim 12, wherein the diamond particles have an average diameter of 10pm to 15pm.

19. A floor surfacing machine, comprising a tool according to any one of the preceding claims.

20. A tool as defined in claim 1 and substantially as shown in LO one or more of the accompanying Figures.

21. A floor surfacing machine, comprising a tool according to claim 20.

22. A hard floor surface maintaining system wherein said floor surface comprises stone or stone-like material, the system 15 comprising: a first flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, and presenting an active treatment surface presenting first abrasive particles bonded to the pad, the first abrasive particles comprising diamond 20 particles having a first average diameter; and a second flexible pad comprising an open, lofty, three dimensional non-woven web of fibers, and presenting an active treatment surface presenting second abrasive particles bonded to the pad, the second abrasive particles comprising diamond 25 particles having a second average diameter, wherein the first flexible pad presents a first portion wherein the diamond particles are present in a first concentration, and a second portion where the diamond particles are present in a second, lower concentration, 30 wherein the second flexible pad presents a first portion wherein the diamond particles are present in a first 38 concentration, and a second portion wherein the diamond particles are present in a second, lower concentration, and wherein the first average diameter is greater than the second average diameter. 5

23. The system as claimed in claim 22, wherein the first pad and second flexible pads are visually different from each other.

24. The system as claimed in claim 23, wherein the first and second flexible pads present different colors. Dated: 29 April 2009 -0