Patent Application
20050076936
The present invention relates to cleaning pads and cleaning implements for cleaning hard surfaces, and in particular floors. More particularly, the present invention relates to pre-moistened cleaning pads.
Numerous implements are known for cleaning hard surfaces such as tiled floors, linoleum floors, hardwood floors, counter tops and the like. In the context of cleaning floors, suitable implements typically comprise a handle and means for applying a liquid cleaning composition. Some implements are reusable, including mops containing cotton strings, cellulose and/or synthetic strips, sponges, and the like. While these mops are successful in removing many soils from hard surfaces, they typically require the inconvenience of performing one or more rinsing steps during use to avoid saturation of the material with dirt, soil, and other residues. This requires the use of a separate container to perform the rinsing step(s), and typically these rinsing steps fail to sufficiently remove dirt residues. This can result in redeposition of significant amounts of soil during subsequent passes of the mop. Furthermore, as reusable mops are used over time, they become increasingly soiled and malodorous. This negatively impacts subsequent cleaning performance.
To alleviate some of the negative attributes associated with reusable cleaning implements, mops having disposable cleaning pads have been provided. For example, WO-A-0027271 describes a cleaning implement comprising a handle and a head portion pivotally attached thereto, and a removable cleaning pad for attachment to the head portion, the cleaning pad comprising at least one absorbent layer and various other optional features. The absorbent layer may be pre-moistened, or impregnated, with a liquid cleaning composition prior to attachment to the head portion of the cleaning implement, either by the manufacture of the cleaning pads, or by the consumer.
Pre-moistened cleaning pads of this type are commercially available from the Applicant under the registered trade mark Swiffer Wet®. Typically, a plurality of pre-moistened pads are provided in a container in such a manner as to allow easy attachment to the head of a cleaning implement, by inserting the head of the cleaning implement into the container, thus avoiding extensive contact between the cleaning pad and the consumer's hands. Suitable instructions are also provided. However, despite these instructions, it is believed that about 75% of consumers attach pre-moistened cleaning pads to a mop head while the mop is held inverted between their legs. It is suspected that this is a habit created from the use of dry cleaning pads. Irrespective of this, attachment of the cleaning pad tends to take several seconds, allowing drippage to occur while the pad is being held essentially upright. It would be desirable to reduce this drippage.
EP 0 112 654 (assigned to Unilever NV) describes a cleaning substrate having an absorbent core sandwiched between two nonwoven outer layers. In order to bond the various layers together to form a unitary structure, the absorbent core is perforated at regular intervals through which the outer layers are spotbonded together. Other methods for bonding nonwoven layers together are described in U.S. Pat. No. 5,964,742, and in U.S. Pat. No. 3,855,046 (both assigned to Kimberly-Clark Worldwide, Inc.).
According to a first aspect of the present invention, various types of cleaning pad are defined in claims 1 and 15. The discrete fluid reservoirs formed in the above-mentioned cleaning pads restrain fluid flow to the edges of the pad, thereby reducing drippage experienced on attaching the cleaning pad to a cleaning implement while held inverted between a consumer's legs.
According to a second aspect of the present invention a cleaning implement comprises a handle; a head portion attached to the handle; and, removably attached to the head portion, a cleaning pad of any of the types described above.
According to a third aspect of the present invention, a cleaning kit comprises a cleaning implement comprising a handle and a head portion attached thereto, and a cleaning pad of any of the types described above.
According to a fourth aspect of the present invention, a method of cleaning a hard surface (eg. a floor) comprises providing a cleaning implement comprising a handle and a head portion attached thereto; removably attaching to the head portion a cleaning pad of any of the types described above; wiping the surface to be cleaned with the cleaning pad; and optionally, removing the cleaning pad.
As used herein, the term “x-y dimension” refers to the plane orthogonal to the thickness of the cleaning pad, or a component thereof. The x and y dimensions correspond to the length and width, respectively, of the cleaning pad or a pad component. In this context, the length of the pad is the longest dimension of the pad, and the width the shortest. In general, in use, a cleaning implement will be moved in a direction parallel to the y-dimension (or width) of the pad. Of course, the present invention is not limited to the use of cleaning pads having four sides. Other shapes, such as circular, elliptical, and the like, can also be used. When determining the width of the pad at any point in the z-dimension, it is understood that the pad is assessed according to its intended use.
As used herein, the term “z-dimension” refers to the dimension orthogonal to the length and width of the cleaning pad of the present invention, or a component thereof. The z-dimension therefore corresponds to the thickness of the cleaning pad or a pad component.
As used herein, an “upper” sheet or layer of a cleaning pad is a sheet or layer that is relatively further away from the surface that is to be cleaned (i.e., in the implement context, relatively closer to the implement handle during use). The term “lower” sheet or layer conversely means a sheet or layer of a cleaning pad that is relatively closer to the surface that is to be cleaned (i.e., in the implement context, relatively further away from the implement handle during use).
As used herein, the “leading” or “front” edge of a cleaning pad is that edge which on a forwards wiping motion crosses the surface to be cleaned in advance of the opposing “trailing” or “rear” edge of the cleaning pad.
The cleaning pad comprises an absorbent structure, which may be a monolayer or multilayer structure. In a preferred embodiment the absorbent structure comprises an absorbent core sandwiched between an upper sheet and a lower sheet. In this case, each discrete reservoir comprises a discrete portion of the absorbent core. However, an absorbent structure comprising only two layers is also envisaged. Furthermore, the cleaning pad may comprise layers in addition to its absorbent structure.
The absorbent structure comprises any material capable of absorbing and retaining fluid during use. Typically, the absorbent structure comprises fibrous material, preferably nonwoven fibrous material. Fibers useful in the present invention include those that are naturally occurring (modified or unmodified), as well as synthetically made fibers. Examples of suitable unmodified/modified naturally occurring fibers include cotton, Esparto grass, bagasse, kemp, flax, silk, wool, wood pulp, chemically modified wood pulp, jute, ethyl cellulose, and cellulose acetate. Suitable synthetic fibers can be made from polyvinyl chloride, polyvinyl fluoride, polytetra-fluoroethylene, polyvinylidene chloride, polyacrylics such as ORLON®, polyvinyl acetate, Rayon®, polyethylvinyl acetate, non-soluble or soluble polyvinyl alcohol, polyolefins such as polyethylene (e.g., PULPEX®) and polypropylene, polyamides such as nylon, polyesters such as DACRON® or KODEL®, polyurethanes, polystyrenes, and the like. The absorbent core can comprise solely naturally occurring fibers, solely synthetic fibers, or any compatible combination of naturally occurring and synthetic fibers.
The fibers useful herein can be hydrophilic, hydrophobic or can be a combination of both hydrophilic and hydrophobic fibers. As used herein, the term “hydrophilic” is used to refer to surfaces that are wettable by is aqueous fluids deposited thereon. Hydrophilicity and wettability are typically defined in terms of contact angle and the surface tension of the fluids and solid surfaces involved. This is discussed in detail in the American Chemical Society publication entitled “Contact Angle, Wettability and Adhesion”, edited by Robert F. Gould (Copyright 1964. A surface is said to be wetted by a fluid (i.e., hydrophilic) when either the contact angle between the fluid and the surface is less than 90°, or when the fluid tends to spread spontaneously across the surface, both conditions normally co-existing. Conversely, a surface is considered to be “hydrophobic” if the contact angle is greater than 90° and the fluid does not spread spontaneously across the surface.
The particular selection of hydrophilic or hydrophobic fibers will depend upon the other materials included in the cleaning pad, for instance in different absorbent layers. That is, the nature of the fibers will be such that the cleaning pad exhibits the necessary fluid delay and overall fluid absorbency. Suitable hydrophilic fibers for use in the present invention include cellulosic fibers, modified cellulosic fibers, rayon, polyester fibers such as hydrophilic nylon (HYDROFIL®). Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as surfactant-treated or silica-treated thermoplastic fibers derived from, for example, polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and the like.
Suitable wood pulp fibers can be obtained from well-known chemical processes such as the Kraft and sulfite processes. It is especially preferred to derive these wood pulp fibers from southern soft woods due to their premium absorbency characteristics. These wood pulp fibers can also be obtained from mechanical processes, such as ground wood, refiner mechanical, thermomechanical, chemimechanical, and chemi-thermomechanical pulp processes. Recycled or secondary wood pulp fibers, as well as bleached and unbleached wood pulp fibers, can be used.
Another type of hydrophilic fiber for use in the present invention is chemically stiffened cellulosic fibers. As used herein, the term “chemically stiffened cellulosic fibers” means cellulosic fibers that have been stiffened by chemical means to increase the stiffness of the fibers under both dry and aqueous conditions. Such means can include the addition of a chemical stiffening agent that, for example, coats and/or impregnates the fibers. Such means can also include the stiffening of the fibers by altering the chemical structure, e.g., by crosslinking polymer chains.
Where fibers are used as the absorbent structure (or a constituent component thereof), the fibers can optionally be combined with a thermoplastic material. Upon melting, at least a portion of this thermoplastic material migrates to the intersections of the fibers, typically due to interfiber capillary gradients. These intersections become bond sites for the thermoplastic material. When cooled, the thermoplastic materials at these intersections solidify to form the bond sites that hold the matrix or web of fibers together in each of the respective layers. This can be beneficial in providing additional overall integrity to the cleaning pad.
Amongst its various effects, bonding at the fiber intersections increases the overall compressive modulus and strength of the resulting thermally bonded member. In the case of the chemically stiffened cellulosic fibers, the melting and migration of the thermoplastic material also has the effect of increasing the average pore size of the resultant web, while maintaining the density and basis weight of the web as originally formed. This can improve the fluid acquisition properties of the thermally bonded web upon initial exposure to fluid, due to improved fluid permeability, and upon subsequent exposure, due to the combined ability of the stiffened fibers to retain their stiffness upon wetting and the ability of the thermoplastic material to remain bonded at the fiber intersections upon wetting and upon wet compression. In net, thermally bonded webs of stiffened fibers retain their original overall volume, but with the volumetric regions previously occupied by the thermoplastic material becoming open to thus increase the average inter fiber capillary pore size.
Thermoplastic materials useful in the present invention can be in any of a variety of forms including particulates, fibers, or combinations of particulates and fibers. Thermoplastic fibers are a particularly preferred form because of their ability to form numerous interfiber bond sites. Suitable thermoplastic materials can be made from any thermoplastic polymer that can be melted at temperatures that will not extensively damage the fibers that comprise the primary web or matrix of each layer. Preferably, the melting point of this thermoplastic material will be less than about 90° C., and preferably between about 75° C. and about 175° C. In any event, the melting point of this thermoplastic material should be no lower than the temperature at which the thermally bonded absorbent structures, when used in the cleaning pads, are likely to be stored. The melting point of the thermoplastic material is typically no lower than about 50° C.
The thermoplastic materials, and in particular the thermoplastic fibers, can be made from a variety of thermoplastic polymers, including polyolefins such as polyethylene (e.g., PULPEX®) and polypropylene, polyesters, copolyesters, polyvinyl acetate, polyethylvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylics, polyamides, copolyamides, polystyrenes, polyurethanes and copolymers of any of the foregoing such as vinyl chloride/vinyl acetate, and the like. Depending upon the desired characteristics, suitable thermoplastic materials include hydrophobic fibers that have been made hydrophilic, such as surfactant-treated or silica-treated thermoplastic fibers derived from, for example, polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and the like. The surface of the hydrophobic thermoplastic fiber can be rendered hydrophilic by treatment with a surfactant, such as a nonionic or anionic surfactant, e.g., by spraying the fiber with a surfactant, by dipping the fiber into a surfactant or by including the surfactant as part of the polymer melt in producing the thermoplastic fiber. Upon melting and resolidification, the surfactant will tend to remain at the surfaces of the thermoplastic fiber. Suitable surfactants include nonionic surfactants such as Brij® 76 manufactured by ICI Americas, Inc. of Wilmington, Del., and various surfactants sold under the Pegosperse® trademark by Glyco Chemical, Inc. of Greenwich, Conn. Besides nonionic surfactants, anionic surfactants can also be used. These surfactants can be applied to the thermoplastic fibers at levels of, for example, from about 0.2 to about 1 g. per sq. of centimeter of thermoplastic fiber.
Suitable thermoplastic fibers can be made from a single polymer (monocomponent fibers), or can be made from more than one polymer (e.g., bicomponent fibers). As used herein, “bicomponent fibers” refers to thermoplastic fibers that comprise a core fiber made from one polymer that is encased within a thermoplastic sheath made from a different polymer. The polymer comprising the sheath often melts at a different, typically lower, temperature than the polymer comprising the core. As a result, these bicomponent fibers provide thermal bonding due to melting of the sheath polymer, while retaining the desirable strength characteristics of the core polymer.
Suitable bicomponent fibers for use in the present invention can include sheath/core fibers having the following polymer combinations: polyethylene/poly-propylene, polyethylvinyl acetate/polypropylene, poly-ethylene/polyester, polypropylene/polyester, copolyester/ polyester, and the like. Particularly suitable bicomponent thermoplastic fibers for use herein are those having a polypropylene or polyester core, and a lower melting copolyester, polyethylvinyl acetate or polyethylene sheath (e.g., those available from Danaklon a/s and Chisso Corp.). These bicomponent fibers can be concentric or eccentric. As used herein, the terms “concentric” and “eccentric” refer to whether the sheath has a thickness that is even, or uneven, through the cross-sectional area of the bicomponent fiber. Eccentric bicomponent fibers can be desirable in providing more compressive strength at lower fiber thicknesses. Preferred bicomponent fibers comprise a copolyolefin bicomponent fiber comprising less than about 81% polyethylene terephthalate core and a less than about 51% copolyolefin sheath. Such a preferred bicomponent fiber is commercially available from the Hoechst Celanese Corporation, in New Jersey, under the trade name CELBOND® T-255. The amount of bicomponent fibers will preferably vary according to the density of the material in which it is used.
Methods for preparing thermally bonded fibrous materials are described in U.S. Pat. No. 5,607,414 (Richards et al), issued Mar. 4, 1997; and U.S. Pat. No. 5,549,589 (Horney et al) issued Aug. 27, 1996 (see especially columns 9 to 10).
It may be desirable to include in the absorbent structure a material having a relatively high capacity (in terms of grams of fluid per gram of absorbent material). As used herein, the term “superabsorbent material” means any absorbent material having a g/g capacity for water of at least about 15 g/g, when measured under a confining pressure of 0.3 psi. Because a majority of the cleaning fluids useful with the present invention are aqueous based, it is preferred that the superabsorbent materials have a relatively high g/g capacity for water or water-based fluids.
Superabsorbent gelling polymers useful in the present invention include a variety of water-insoluble, but water-swellable (gelling) polymers capable of absorbing large quantities of fluids. Such polymeric materials are also commonly referred to as “hydrocolloids”, and can include polysaccharides such as carboxymethyl starch, carboxymethyl cellulose, and hydroxypropyl cellulose; nonionic types such as polyvinyl alcohol and polyvinyl ethers; cationic types such as polyvinyl pyridine, polyvinyl morpholinione, and N,N-dimethylaminoethyl or N,N-diethylaminopropyl acrylates and methacrylates, and the respective quaternary salts thereof. Well-known materials and are described in greater detail, for example, in U.S. Pat. No. 4,076,663 (Masuda et al), issued Feb. 28, 1978, and in U.S. Pat. No. 4,062,817 (Westerman), issued Dec. 13, 1977.
Preferred superabsorbent gelling polymers contain carboxy groups. These polymers include hydrolyzed starch-acrylonitrile graft copolymers, partially neutralized hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially neutralized starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, slightly network crosslinked polymers of any of the foregoing copolymers, partially neutralized polyacrylic acid, and slightly network crosslinked polymers of partially neutralized polyacrylic acid. These polymers can be used either solely or in the form of a mixture of two or more different polymers. Examples of these polymer materials are disclosed in U.S. Pat. No. 3661,875, U.S. Pat. No. 4,076,663, U.S. Pat. No. 4,093,776, U.S. Pat. No. 4,666,983, and U.S. Pat. No. 4,734,478.
Most preferred polymer materials for use in making the superabsorbent gelling polymers are slightly network crosslinked polymers of partially neutralized polyacrylic acids and starch derivatives thereof. Most preferably, the hydrogel-forming absorbent polymers comprise from about 50 to about 95%, preferably about 75%, neutralized, slightly network crosslinked, polyacrylic acid (i.e. poly (sodium acrylate/acrylic acid)). Network crosslinking renders the polymer substantially water-insoluble and, in part, determines the absorptive capacity and extractable polymer content characteristics of the superabsorbent gelling polymers. Processes for network crosslinking these polymers and typical network crosslinking agents are described in greater detail in U.S. Pat. No. 4,076,663.
Where superabsorbent material is included in the absorbent structure, the absorbent structure will preferably comprise at least about 15%, by weight of the absorbent structure, more preferably at least about 20%, still more preferably at least about 25%, of the superabsorbent material.
Where the cleaning pad comprises an absorbent core, the core may comprise any of the above materials. Similarly, where the cleaning pad comprises an upper sheet and a lower sheet, they too may comprise any of the above absorbent materials, or may be non-absorbent but fluid pervious in nature. If the upper and/or lower sheet is absorbent, it will typically have lower absorbency than the absorbent core. The upper sheet and the lower sheet may comprise separate sheet materials, or may be portions of the same sheet material, for instance which is wrapped around the absorbent core. Furthermore, the upper sheet and lower sheet may each independently comprise a monolayer or multilayer structure, and additional components may be included between the upper and/or lower sheet and the absorbent core.
The cleaning pad may comprise components, which may take the form of layers, in addition to the absorbent structure.
The cleaning pad comprises a plurality of discrete fluid reservoirs. As used herein, “discrete” fluid reservoirs are reservoirs for containing a fluid, and in particular a liquid cleaning composition, which are separated from one another, either simply by the walls of the individual reservoirs if the reservoirs are adjacent one another, or by portions of the cleaning pad if the reservoirs are spaced apart.
Typically, the reservoirs are formed by bonding or embossing throughout the thickness of the absorbent structure. In the context of a monolayer absorbent structure, this typically means that the opposing surfaces of the absorbent structure are brought together at selected locations. In the context of a multilayer absorbent structure, typically this means that the outer layers of the multilayer structure are brought together, preferably by bonding those layers together, at selected locations. For instance, where the absorbent structure comprises an upper sheet, a lower sheet, and an absorbent core positioned therebetween, preferably the upper sheet is bonded to the lower sheet at selected locations to define discrete fluid reservoirs, with the result that each reservoir will contain a discrete portion of the absorbent core.
Bonding may be achieved by the application of heat and/or pressure or ultrasonically. Typically, when the reservoirs are formed by bonding through the cleaning pad, the bond strength will be greater than 30 grams force, without the use of an adhesive.
A virtually unlimited number of shapes and sizes of fluid reservoirs may be envisaged. For instance, the reservoirs may have a shape selected from circles, squares, rectangles, diamonds, ovals, triangles, hexagons and combinations thereof.
Other shapes may also be envisaged. In the latter case, the reservoirs may be formed by intersecting bond lines, preferably extending between different side edges of the cleaning pad. For instance, the bond lines may form an acute angle with the side edges of the cleaning pad, or they may extend substantially parallel to those side edges.
Preferably, adjacent fluid reservoirs are in fluid communication with one another. By this we mean that fluid is able to pass between adjacent reservoirs. However, fluid communication should be somewhat limited, in order to achieve the desired restraint on fluid flow to the side edges of the cleaning pad, to reduce or avoid drippage during attachment to a cleaning implement. Fluid communication maybe achieved through provision of narrow channels between the reservoirs, which may result from the process used to form the reservoirs, as is described in more detail below. Such channels will typically have a cross-sectional area in the range 0.01 to 0.05 sq. in., typically 0.015 to 0.045 sq. in.
A preferred bonding method for forming the reservoirs is described in U.S. patent application Ser. No. 10/456288, filed on Jun. 6, 2003 (McFall et al.). This method is now described in the context of a cleaning pad comprising an upper sheet, a lower sheet and an absorbent core sandwiched therebetween, but is applicable to other absorbent structures. In essence, the method comprises localized compression of the cleaning pad which causes the core material to fracture and separate (ie. move away from the pressure point), while the upper sheet and the lower sheet remain intact. As a result there is a clear path for the upper sheet and the lower sheet to bond together, and preferably very little (if any) of the core material is actually left in the bond sites. Rather, discrete portions of the core material is enclosed within the resulting fluid reservoirs.
In this method, the upper sheet and the lower sheet comprise any material(s) capable of bonding together by the application of heat and/or pressure, adhesives or ultrasonics. Suitable materials include woven and nonwoven materials; polymeric materials such as apertured formed thermoplastic films, apertured or unapertured plastic films, and hydroformed thermoplastic films; porous foams, reticulated foams; reticulated thermoplastic films; and thermoplastic scrims. Suitable woven and nonwoven materials can be comprised of natural fibers or synthetic fibers as described before, or from a combination of natural and synthetic fibers. Preferred materials are thermoplastics materials. However, particularly if adhesives or other types of bonding are used, materials other than thermoplastic materials may be preferred. For instance, the top sheet and backing sheet may each comprise a cellulosic material that can be bonded to itself by hydrogen bonding.
The bonding process typically comprises feeding a laminate, for instance comprising an upper sheet, an absorbent core and a lower sheet, through at least a pair of cylindrical rolls, with at least one of the rolls having a relief pattern on its surface formed by a plurality of protruberances or pattern elements extending outwardly from the surface of the roll.
The other cylindrical roll serves as an anvil member, and together the patterned roll and the anvil roll define a pressure biased nip therebetween. Preferably, the anvil is smooth-surfaced, however both rolls may have a relief pattern thereon. The patterned roll and anvil roll are preferably biased towards each other with a loading of from about 20,000 psi (about 140 MPa) to about 200,000 psi (about 1400 MPa).
The patterned roll and the anvil roll are preferably driven in the same direction at different speeds, so that there is a surface velocity differential therebetween. The surface velocity differential preferably has a magnitude of from about 2 to about 40% of the roll having the lower surface velocity, more preferably between about 2 to about 20%. The anvil roll is preferably operated at a surface velocity that is greater than that of the patterned roll. It is also possible, however, that high line velocities for bonding to occur at zero velocity differential.
The relief pattern may take a variety of forms, and can be continuous or intermittent, depending upon the nature of the fluid reservoirs desired to be formed. If the relief pattern is continuous, the result will be a continuous bond. If the relief pattern is intermittent, the result will be that apertures, or gaps, exist in the bond, which may allow for fluid communication between adjacent reservoirs, as described above. In this case, the bond may be considered as comprising a plurality of bond sites, the dimensions of which depend upon the size, shape and distance of separation of the protruberances making up the relief pattern. Preferably, the protruberances, and therefore the resulting bond sites, have an aspect ratio of less than 0.10, more preferably in the range from 0.02 to 0.085, and most preferably in the range from 0.03 to 0.083. In this context, the aspect ratio is defined as minor axis:major axis. Furthermore, the separation, or distance between adjacent bond sites is preferably in the range 0.015 to 0.05 in.
The protruberances or pattern elements may also take a variety of forms, as can the land surfaces (ie. the outermost surfaces) of the protruberances. The protruberances generally have side walls that are not perpendicular to the surface of the respective cylindrical roll. Preferably, for instance, the side walls form an angle of greater than 45° than 90°, preferably between about 70° to 90°, with the surface of the cylindrical roll.
Suitable shapes for the land surfaces include, but are not limited to, oval, circular, rectangular, square and triangular. The land surfaces may also be of a variety of sizes, for instance having an area ranging from 0.0001 sq. in. to 0.003 sq. in., resulting in a bond site of substantially the same area.
Optionally, prior to bonding, the absorbent core may be slit or cut to form particulate material, in a pattern corresponding to the desired bonded pattern. It is, however, important that the materials from which the upper sheet and lower sheet are selected are such that they remain intact during this optional cutting step. Cutting may be achieved by passing the laminate of absorbent core, upper sheet and lower sheet through a pair of cylindrical rolls, each of which has a patterned surface thereon, preferably formed by a plurality of ridges and valleys defining a plurality of triangularly-shaped teeth. The cylindrical roll subject the laminate to a mechanical straining process which applies a force that is greater than the yield-to-break point of the absorbent core, but less than that of the upper sheet and the lower sheet. Thus, the absorbent core is at least partially slit without slitting the upper sheet or the lower sheet.
Another bonding method for forming the reservoirs comprises ultrasonic bonding, and suitable equipment for this purpose includes Branson Ultrasonic Unit Model 900 BCA. For example, the components of the cleaning pad to be bonded are arranged on a plate patterned according to the desired reservoirs, and compressed, for instance using a pressure of about 30 psig, while welding the cleaning pad ultrasonically.
The selection of bond area is important for minimizing a performance reduction in absorption. As can be expected, the higher the bond area, the greater the reduction in pad absorption, and thus pad mileage. Preferably the total bond area across the entirety of the cleaning pad (in the x-y plane) is less than 10%, more preferably less than 5%, and most preferably less than 3%. Bond area is measured, for instance, using Auto Cad LT 98 software in accordance with the following method:
The depth of bonding relative to the unbonded area of the cleaning pad (ie. prior to any bonding) is also important to the consumer's perception of scrubbing ability and actual scrubbing performance. Preferably, the cleaning pad has a bond depth index (BDI) of 0.15, and preferably less than 0.10, to achieve a good balance between absorption performance, drippage and aesthetic considerations. The BDI is calculated by dividing the average caliper of the bond area by the average caliper of the unbonded area, ie. prior to any bonding. Typically, the cleaning pad has an unbonded thickness of at least up to 2 mm, preferably up to 4 mm.
The cleaning pad may comprise various optional features. For instance, the cleaning pad may comprise a scrubbing strip, preferably located on a portion of the pad which does not make contact with the surface to be cleaned during the normal cleaning operation. In other words, the scrubbing strip is preferably positioned on the cleaning pad such that, on attachment to the head portion of a cleaning implement, the scrubbing strip extends along a side edge of the head portion. Alternatively, the scrubbing strip may be positioned on the floor-contacting lower surface of the cleaning pad.
The scrubbing strip necessarily comprises an abrasive material, to remove tough stains. Suitable materials include those often used for making scouring pads, typically polymers or polymer blends with or without specific abrasives. Examples of suitable polymers include thermoplastic polymers such as polypropylene, high density polyethylene, polyesters (eg., polyethylene terephthalate), nylon, polystyrene, and blends and copolymers thereof.
An alternative to using materials found in typical scouring pads is to use brushes containing bristles to achieve scrubbing. Such bristles are typically composed of polymer or polymer blends, with or without abrasives. In the context of brushes, bristles made of nylon again are preferred because of rigidity, stiffness, and/or durability. A preferred nylon bristle is that commercially available from 3M Corp. under the trade name Tynex® 612 nylon. These bristles have shown less water absorption versus commercial Nylon 66. Reducing the ability of the present adhesive scrubbing strips to absorb water is important since water absorption decreases bristle stiffness and recovery while impacting scrubbing ability.
Another approach is to use netting or scrim materials to form the scrubbing strip. Again, the netting or scrim is typically composed of a polymer or polymer blend, either with or without abrasives. The netting or scrim is typically wrapped around a secondary structure to provide some bulk. The shape of the holes in the netting can include, but is not limited to, a variety of shapes such as squares, rectangles, diamonds, hexagons or mixtures thereof. Typically, the smaller the area composed by the holes in the netting the greater the scrubbing ability. This is primarily due to the fact that there are more points where the scrim material intersects, as it is these intersection points that will contact the floor. An alternative to wrapping netting or scrim is to apply molten extruded polymers directly onto a secondary structure such as a non-woven. Upon curing the polymer would create high point stiffer material as compared to the secondary non-woven which in turn provides scrubbing ability.
Yet another alternative is for the scrubbing strip to comprise abrasive or coarse particulate material. A suitable particulate material comprises coarse inks available from Polytex® or coarse polymers from Vinamul, like Acrylic ABX-30.
The scrubbing strip may be a monolayer or multilayer structure. Preferred scrubbing layers take the form of film materials, provided that they have the necessary flexural rigidity to withstand repeated scrubbing actions. Suitable film materials generally have a thickness of at least 2 mils and a flexural rigidity of at least 0.10 g cm2/cm, measured using the Kawabata bending tester.
Preferred film materials are pervious to liquids, and in particular liquids containing soils, and yet are non-absorbent and have a reduced tendency to allow liquids to pass back through their structure and rewet the surface being cleaned. Thus, the surface of the film tends to remain dry during the cleaning operation, thereby reducing filming and streaking of the surface being cleaned and permitting the surface to be wiped substantially dry.
Preferably the film material comprises a plurality of protrusions extending outwardly from the film surface and away from the body of the cleaning pad. Alternatively, or additionally, the film may comprise a plurality of apertures. The protrusions and/or apertures formed in the above-described film materials may be of a variety of shapes and/or sizes.
The cleaning pad may comprise a scrubbing layer which, when attached to the cleaning implement, extends over the lower surface of the head portion of that cleaning implement. The lower sheet of the cleaning pad may take the form of a scrubbing layer. Typically, the scrubbing layer is outermost on the cleaning pad, and thus contacts the surface to be cleaned during the normal course of the cleaning operation. In this case, the scrubbing layer must necessarily be of lower abrasiveness than the scrubbing strip, in order not to damage the surface being cleaned.
The scrubbing layer may be a mono-layer or a multilayer structure. A wide range of materials are suitable for use in the scrubbing layer, for instance as disclosed in WO-A-0027271. In particular, the scrubbing layer may comprise woven and nonwoven materials; polymeric materials such as apertured formed thermoplastic films, apertured plastic films, and hydroformed thermoplastic films; porous foams; reticulated foams; reticulated thermoplastic films; and thermoplastic scrims.
The cleaning pad also typically comprises attachment means for attaching the pad to a cleaning implement. Alternatively, the cleaning implement itself may include suitable attachment means. For instance, the cleaning pad may have an attachment layer that allows the pad to be connected to the implement's handle or head portion. The attachment layer can be necessary in those embodiments where the absorbent layer is not suitable for attaching the pad to the cleaning implement. The attachment layer can also function as a means to prevent fluid flow through the top surface (i.e., the handle-contacting surface) of the cleaning pad, and can further provide enhanced integrity of the pad. As with the scrubbing and absorbent layers, the attachment layer can consist of a mono-layer or a multi-layer structure, so long as it meets the above requirements.
In a preferred embodiment of the present invention, the attachment layer will comprise a surface which is capable of being mechanically attached to the head portion of a cleaning implement by use of known hook and loop technology. In such an embodiment, the attachment layer will comprise at least one surface which is mechanically attachable to hooks that are permanently affixed to the bottom surface of the head portion.
In an alternative embodiment, the attachment layer can have a y-dimension (width) that is greater than the y-dimension of the other cleaning pad elements such that the attachment layer can then engage attachment structures located on a mop head of a handle of a cleaning implement.
The cleaning pad may be designed to have multiple cleaning surfaces or edges, each of which contact the soiled surface during the cleaning operation. In the context of a cleaning implement such as a mop, these surfaces or edges are provided such that during the typical cleaning operation (i.e., where the implement is moved back and forth in a direction substantially parallel to the pad's y-dimension or width), each of the surfaces or edges contact the surface being cleaned as a result of “rocking” of the cleaning pad. The effect of multiple edges is achieved by constructing the pad such that it has multiple widths through its dimension. That is, these multiple widths form a plurality of surfaces or edges along the front and rear of the pad. This aspect is discussed in more detail in WO-A-0027271.
The cleaning pad may also include one or more “free-floating” functional cuffs. Such cuffs improve the cleaning performance of the cleaning pad, by improving particulate pick-up. As a cleaning pad comprising functional cuff(s) is wiped back and forth across a hard surface, the functional cuff(s) “flip” from side to side, thus picking-up and trapping particulate matter. Cleaning pads having functional cuff(s) exhibit improved pick-up and entrapment of particulate matter, which are typically found on a hard surfaces, and have a reduced tendency to redeposit such particulate matter on the surface being cleaned. Functional cuffs can comprise a variety of materials, including, but not limited to, carded polypropylene, rayon or polyester, hydroentangled polyester, spun-bonded polypropylene, polyester, polyethylene, cotton, polypropylene, or blends thereof. Functional cuffs can be formed as an integral part of the cleaning pad, or can be separately adhered to the cleaning pad. If the functional cuffs are an integral part of the cleaning pad, the functional cuffs are preferably a looped functional cuff formed by crimping a lower portion of the cleaning pad, for example, in a Z-fold and/or C-fold. Alternatively, the functional cuffs can be separately adhered to the cleaning pad via a variety of methods known in the art including, but not limited to, double-sided adhesive tape, heat bonding, gluing, ultrasonic welding, stitching, high-pressure mechanical welding, and the like. Preferably, the cleaning pad comprises two functional cuffs situated at or near opposite edges (e.g., the leading and trailing edges of the pad, in terms of the y-dimension) of the cleaning pad. Preferably, the functional cuff(s) are placed in a location such that their length is perpendicular to the back and forth mopping or wiping direction used by the consumer.
In order to increase the resiliency of an absorbent layer having a relatively low density, a thermoplastic material, preferably a bicomponent fiber, is combined with the fibers of the absorbent layer. Upon melting, at least a portion of this thermoplastic material migrates to the intersections of the fibers, typically due to interfiber capillary gradients. These intersections become bond sites for the thermoplastic material. When cooled, the thermoplastic materials at these intersections solidify to form the bond sites that hold the matrix or web of fibers together in each of the respective layers. This can be beneficial in providing additional overall integrity to the cleaning pad. In order to provide the desired resiliency, an absorbent layer having a density of less than about 0.05 g/cm3 preferably comprises at least about 20%, preferably at least about 30%, more preferably at least about 40%, of a thermoplastic material such as a bicomponent fiber. A preferable bicomponent fiber comprises a copolyolefin bicomponent fiber comprising a less than about 81% polyethylene terephthalate core and a less than about 51% copolyolefin sheath and is commercially available from the Hoechst Celanese Corporation under the tradename CELBOND® T-255.
The size of the cleaning pad is determined by the cleaning implement to which it is to be attached. Typically, however, the cleaning pad will have dimensions in the range 100 to 300 mm×100 to 300 mm (expressed as (x-dimension)×(y-dimension)). Furthermore, the thickness of the cleaning pad (expressed as z-dimension) is typically in the range 1 mm to 5 mm, more preferably in the range 2 mm to 4 mm, although again this will depend upon the application to which the cleaning pad is to be put.
The cleaning pad may include a variety of other optional features, including those disclosed in detail in WO-A-0027271, which is incorporated herein by reference.
The present invention extends not only to the cleaning pads defined in the claims, but also to cleaning pads comprising an absorbent structure having discrete fluid reservoirs defined therein, and any one or more of a number of optional features as also described above, for instance a scrubbing strip; a scrubbing layer; one or more functional cuffs; sections having different degrees of absorbency, a density gradient; and combinations thereof.
The cleaning pad is typically supplied to the consumer pre-moistened with a liquid cleaning composition. Suitable liquid cleaning compositions are well known in the art, for instance being disclosed in WO-A-0027271 and WO-A-0123510. The cleaning pad may be pre-moistened prior to or after formation of the fluid reservoirs, but preferably it is pre-moistened after their formation.
The cleaning pad may be used with a variety of cleaning implements. One example of a suitable cleaning implement is in the form of a mop comprising a handle and a head portion (mop head), which may be pivotally attached to the handle, for instance through a universal joint.
The cleaning implement of the present invention may be used to clean a variety of hard surfaces. Preferably, however, they are used for cleaning floors. These floors may consist of ceramics, porcelain, marble, Formica7, no-wax vinyl, linoleum, wood, quarry tile, brick or cement, and the like.
After attachment of a cleaning pad to the cleaning implement, cleaning is effected by wiping the head portion of the cleaning implement across the surface to be cleaned. A preferred wiping pattern consists of an up-and-down overlapping motion starting in the bottom left hand (or right hand) side of the section to be cleaned, and progressing the wiping pattern across the floor continuing to use up-and-down wiping motions. Wiping is then continued beginning at the top right (or left) side of the section to be cleaned and reversing the direction of the wipe pattern using a side-to-side motion. Another preferred wipe pattern consists of an up-and-down wiping motion, followed by an up-and-down wiping motion in the reverse direction. These thorough preferred wiping patterns allow the pad to loosen and absorb more solution, dirt and germs, and provide a better end result in doing so by minimizing residue left behind. Another benefit of the above wiping patterns is minimization of streaks as a result of improved spreading of solution and the elimination of streak lines from the edges of the pad.
Typically, after cleaning, the cleaning pad is removed and disposed of, and with it the germs and dirt removed from the surface, thereby promoting better hygiene and malodour control. However, the cleaning pad may be used for multiple cleaning, depending upon whether the pad is saturated with liquid and/or dirt. This can be readily ascertained by the consumer.
Typically, a plurality of cleaning pads are provided in a container or film wrapping for supply to the consumer, typically with instructions for attachment to a cleaning implement. Kits comprising a cleaning implement and cleaning pad are also provided, again typically with suitable operating instructions.
The present invention is now further illustrated by reference to the following Example and the accompanying drawings.
With reference to
Referring now to
Two dry Swiffer Wet® pads were bonded throughout their thickness, one pad to comprise a plurality of adjacent diamond-shaped reservoirs (as shown in
Equipment Used
The absorbency of each of the bonded pads and of a non-bonded pad was determined by the following “Performance Under Pressure” (PUP) test method. The absorbency index of the two bonded patterns was then calculated, by dividing each of the embossed pad's absorbency by the absorbency of the non-bonded pad. Each pad was then loaded with squeezed out Swiffer Wet lotion, with the non-bonded pad loaded at 6.2 g liquid/g pad and each of the bonded pads being loaded with 6.2 g liquid/g pad multiplied by the respective pad's absorbency index, in order to create a valid comparison between the different pads.
Each pad was then held upright at a height of 260 mm above the work-surface, and the time until the first drip was measured.
The results are presented in Table 1 below.
The results show that the cleaning pad according to the present invention had a significantly longer average drip time than both the wave-bonded and non-bonded pads.
*The invention
Performance Under Pressure Test
This test determines the gram/gram absorption of deionized water for a cleaning pad that is laterally confined in a funnel/frit assembly under an initial confining pressure of 0.06 psi (about 0.6 kPa). (Depending on the composition of the cleaning pad sample, the confining pressure can decrease slightly as the sample absorbs water and swells during the time of the test.) The objective of the test is to assess the ability of a cleaning pad to absorb fluid, over a practical period of time, when the pad is exposed to usage conditions (horizontal wicking and pressures).
The test fluid for the PUP capacity test is deionized water. This fluid is absorbed by the cleaning pad under demand absorption conditions at near-zero hydrostatic pressure.
A suitable apparatus 510 for this test is shown in
Referring to
The components of apparatus 510 are sized such that the flow rate of deionized water therethrough, under a 10 cm hydrostatic head, is at least 0.01 g/cm2/sec, where the flow rate is normalized by the area of fritted funnel 518. Factors particularly impactful on flow rate are the permeability of the fritted disc in fritted funnel 518 and the inner diameters of glass tubing 524, 530, 534, 542, 546 and 531a, and stopcock valves 528 and 540.
Reservoir 512 is positioned on an analytical balance 516 that is accurate to at least 0.01 g with a drift of less than 0.1 g/hr. The balance is preferably interfaced to a computer with software that can (i) monitor balance weight change at pre-set time intervals from the initiation of the PUP test and (ii) be set to auto initiate on a weight change of 0.01-0.05 g, depending on balance sensitivity. Capillary tubing 524 entering the reservoir 512 should not contact either the bottom thereof or cover 514. The volume of fluid (not shown) in reservoir 512 should be sufficient such that air is not drawn into capillary tubing 524 during the measurement. The fluid level in reservoir 512, at the initiation of the measurement, should be approximately 2 mm below the top surface of fritted disc in fritted funnel 518. This can be confirmed by placing a small drop of fluid on the fritted disc and gravimetrically monitoring its slow flow back into reservoir 512. This level should not change significantly when weight assembly 558 is positioned within funnel 518. The reservoir should have a sufficiently large diameter (e.g., about 14 cm) so that withdrawal of about 40 ml portions results in a change in the fluid height of less than 3 mm.
Prior to measurement, the assembly is filled with deionized water. The fritted disc in fritted funnel 518 is forward flushed so that it is filled with fresh deionized water. To the extent possible, air bubbles are removed from the bottom surface of the fritted disc and the system that connects the funnel to the reservoir. The following procedures are carried out by sequential operation of the 3-way stopcocks:
Steps Nos. 7-9 temporarily “dry” the surface of fritted funnel 518 by exposing it to a small hydrostatic suction of about 5 cm. This suction is applied if the open end of tube 544 extends about 5 cm below the level of the fritted disc in fritted funnel 518 and is filled with deionized water. Typically about 0.04 g of fluid is drained from the system during this procedure. This procedure prevents premature absorption of deionized water when weight 558 and sample 560 assembly is positioned within fritted funnel 518. The quantity of fluid that drains from the fritted funnel in this procedure (referred to as the fritted funnel correction weight, or “Wffc”) is measured by conducting the PUP test (see below) for a time period of 20 minutes without sample/weight assembly 558 and 560. Essentially all of the fluid drained from the fritted funnel by this procedure is very quickly reabsorbed by the funnel when the test is initiated. Thus, it is necessary to subtract this correction weight from weights of fluid removed from the reservoir during the PUP test (see below).
A round die-cut sample 560 is placed in funnel 518. The weight 558 is placed onto sample 560, and the top of funnel 518 is then covered with fritted funnel cover 522. After the balance reading is checked for stability, the test is initiated by opening valves 528 and 540 so as to connect funnel 518 and reservoir 512. With auto initiation, data collection commences immediately, as funnel 518 begins to reabsorb fluid.
Data is recorded at intervals over a total time period of 1200 seconds (20 minutes). PUP absorbent capacity is determined as follows:
t1200 absorbent capacity (g/g)=[Wr(t=0)−Wr(t=1200)−Wffc]/Wds
where t1200 absorbent capacity is the g/g capacity of the pad after 1200 seconds, Wr(t=0) is the weight in grams of reservoir 512 prior to initiation, Wr(t=1200) is the weight in grams of reservoir 512 at 1200 seconds after initiation, Wffc is the fritted funnel correction weight and Wds is the dry weight of the cleaning pad sample.
All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
This application claims the benefit of U.S. Provisional Application No. 60/509559, filed on Oct. 8, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60509559 | Oct 2003 | US |
