Patent Application
20110119850
The present invention generally relates to an apertured wiping cloth having essentially collapse resistant surface projections.
Aperturing of nonwovens is generally known in the art. Aperturing has been used in the hygiene business for improving fluid handling in absorbent personal care articles. See for example U.S. Pat. No. 4,886,632 to Van Iten et al. By placing apertures in the nonwoven coversheet, fluid coming into contact with the cover sheet is more easily passed through the cover sheet to the absorbent core.
In the wiping cloth art, apertured wiping cloths are known. See for example U.S. Pat. No. 4,469,734 to Minto, and U.S. Pat. No. 5,429,854 to Currie. Apertured wiping cloths provide some advantages, such as fluid retention and pick-up. However, the prior art apertured wiping cloths did not have surface projection or had surface projections which are not stable when wetted. As a result, the surface projections would tend to substantially lose their shape during use. That is, prior apertured wiping cloths that had some degree of surface projections typically lost their surface projections when the wiping cloth became wet or during use.
Nonwoven webs with projections are taught in U.S. Pat. No. 4,741,941 to Englebert et al. As taught in the '941 patent, the nonwoven web has hollow projections which extend outward from the surface of the nonwoven web. The projections can be made by a number of processes, but are preferably formed by directly forming the nonwoven web on a surface with corresponding projections, or by forming the nonwoven on an apertured forming surface with a pressure differential sufficient to draw the fibers through the apertures in the forming surface, thereby forming the projections in the nonwoven web. One problem with the surface projections taught in the '941 patent is that the projections are not stable and tend to collapse when the nonwoven web becomes wet.
There is a need in the art for a wiping cloth having apertures and surface projections which are stable and essentially retain their shape during use.
Generally stated, the present invention provides a wiping cloth for wiping both wet and dry surfaces. The wiping cloth has a substrate containing thermoplastic fibers. This substrate has a first side and a second side and the substrate has a plurality of apertures therethrough. At least a portion of the apertures have a plurality of three-dimensional fibrous projections encircling each aperture in the portion. Each three-dimensional fibrous projection contains thermoplastic fibers and a portion of the thermoplastic fibers in each of the three-dimensional fibrous projections are deformed. This deformation of the thermoplastic fibers assists in retaining the shape of the three-dimensional fibrous projections during use.
In an embodiment of the present invention, the substrate is a nonwoven web where the nonwoven web may be a meltblown nonwoven web, a spunbond nonwoven web, a coform nonwoven web, a bonded carded web, a spunlace nonwoven web, a hydroentangled nonwoven web or composites or laminates thereof.
When the nonwoven web is a hydroentangled nonwoven web, the hydroentangled nonwoven web has staple fibers hydraulically entangled with substantially continuous thermoplastic fibers. The staple fibers may be non-cellulosic fibers or cellulosic fibers or a mixture thereof. Suitable non-cellulosic fibers include thermoplastic staple fibers.
In a further embodiment of the present invention, the second side of the substrate has a plurality of three-dimensional projections encircling a second portion of the apertures which extend from the second side of the substrate.
In another embodiment of the present invention, the first side of the substrate has a top surface, and the three-dimensional projections extend from the top surface, each three-dimensional projection has a height of about 5 mm or less. In a further embodiment, the height of the three-dimensional projections is between about 0.3 to about 1.3 mm.
In an additional embodiment of the present invention, the wiping cloth substrate is a nonwoven web containing a mixture of thermoplastic fibers and non-thermoplastic fibers. Generally, the thermoplastic fibers are between 10% and 90%, by weight, of the nonwoven web. In a further embodiment, the thermoplastic fibers make-up between about 10% and 30%, by weight, of the nonwoven web.
In one particular embodiment of the present invention, provided is a wiping cloth for wiping both wet and dry surfaces. The wiping cloth is a substrate is a nonwoven web. This nonwoven web contains substantially continuous thermoplastic fibers and staple fibers, wherein the staple fibers are hydraulically entangled with the substantially continuous thermoplastic fibers. The substrate having a first side and a second side and the substrate having a plurality of apertures therethrough. At least a portion of the apertures defines a plurality of three-dimensional fibrous projections on the first side of the substrate and the three-dimensional fibrous projections encircles each aperture in the portion of apertures. Each three-dimensional fibrous projection contains at least one substantially continuous thermoplastic fibers, wherein the substantially continuous thermoplastic fiber in each of the three-dimensional fibrous projections is deformed, wherein the three-dimensional projections retain their shape during use.
In a further embodiment of the present invention, the nonwoven web substrate has a basis weight between about 33 grams per square meter and 200 grams per square meter.
In yet another embodiment of the present invention, the wiping cloth has an aperture density of about 5 apertures per square centimeter to about 20 apertures per square centimeter.
The present invention provides a wiping cloth which has unique surface and tactile properties, and enhanced wiping performance for wiping both wet and dry surfaces. The wiping cloth also has a visual appearance which will appeal to a user by retaining is shape and function before and during use in both a wet state and a dry state.
It should be noted that, when employed in the present disclosure, the terms “comprises”, “comprising” and other derivatives from the root term “comprise” are intended to be open-ended terms that specify the presence of any stated features, elements, integers, steps, or components, and are not intended to preclude the presence or addition of one or more other features, elements, integers, steps, components, or groups thereof.
As used herein, the term “nonwoven web” or “nonwoven fabric” means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted web. Nonwoven webs have been formed from many processes, such as, for example, meltblowing processes, spunbonding processes, air-laying processes, coforming processes and bonded carded web processes. The basis weight of nonwoven webs is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters are usually expressed in microns, or in the case of staple fibers, denier. It is noted that to convert from osy to gsm, multiply osy by 33.91.
As used herein the term “spunbond fibers” refers to small diameter fibers of molecularly oriented polymeric material. Spunbond fibers may be formed by extruding molten thermoplastic material as fibers from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded fibers then being rapidly reduced as in, for example, U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,542,615 to Dobo et al, and U.S. Pat. No. 5,382,400 to Pike et al. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface and are generally continuous. Spunbond fibers are often about 10 microns or greater in diameter. However, fine fiber spunbond webs (having an average fiber diameter less than about 10 microns) may be achieved by various methods including, but not limited to, those described in commonly assigned U.S. Pat. No. 6,200,669 to Marmon et al. and U.S. Pat. No. 5,759,926 to Pike et al., each is hereby incorporated by reference in its entirety.
Meltblown nonwoven webs are prepared from meltblown fibers. As used herein the term “meltblown fibers” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter (using a sample size of at least 10), and are generally tacky when deposited onto a collecting surface.
As used herein, the term “polymer” generally includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the molecule. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries.
As used herein, the term “multicomponent fibers” refers to fibers or filaments which have been formed from at least two polymers extruded from separate extruders but spun together to form one fiber. Multicomponent fibers are also sometimes referred to as “conjugate” or “bicomponent” fibers or filaments. The term “bicomponent” means that there are two polymeric components making up the fibers. The polymers are usually different from each other, although conjugate fibers may be prepared from the same polymer, if the polymer in each component is different from one another in some physical property, such as, for example, melting point, glass transition temperature or the softening point. In all cases, the polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the multicomponent fibers or filaments and extend continuously along the length of the multicomponent fibers or filaments. The configuration of such a multicomponent fiber may be, for example, a sheath/core arrangement, wherein one polymer is surrounded by another, a side-by-side arrangement, a pie arrangement or an “islands-in-the-sea” arrangement. Multicomponent fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et al.; U.S. Pat. No. 5,336,552 to Strack et al.; and U.S. Pat. No. 5,382,400 to Pike et al.; the entire content of each is incorporated herein by reference. For two component fibers or filaments, the polymers may be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios.
As used herein, the term “multiconstituent fibers” refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend or mixture. Multiconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils or protofibrils which start and end at random. Fibers of this general type are discussed in, for example, U.S. Pat. Nos. 5,108,827 and 5,294,482 to Gessner.
As used herein, the term “substantially continuous fibers” is intended to mean fiber that have a length which is greater than the length of staple fibers. The term is intended to include fibers which are continuous, such as spunbond fibers, and fibers which are not continuous, but have a defined length greater than about 150 millimeters.
As used herein, the term “staple fibers” means fibers that have a fiber length generally in the range of about 0.5 to about 150 millimeters. Staple fibers may be cellulosic fibers or non-cellulosic fibers. Some examples of suitable non-cellulosic fibers that can be used include, but are not limited to, polyolefin fibers, polyester fibers, nylon fibers, polyvinyl acetate fibers, and mixtures thereof. Cellulosic staple fibers include for example, pulp, thermomechanical pulp, synthetic cellulosic fibers, modified cellulosic fibers, and the like. Cellulosic fibers may be obtained from secondary or recycled sources. Some examples of suitable cellulosic fiber sources include virgin wood fibers, such as thermomechanical, bleached and unbleached softwood and hardwood pulps. Secondary or recycled cellulosic fibers may be obtained from office waste, newsprint, brown paper stock, paperboard scrap, etc., may also be used. Further, vegetable fibers, such as abaca, flax, milkweed, cotton, modified cotton, cotton linters, can also be used as the cellulosic fibers. In addition, synthetic cellulosic fibers such as, for example, rayon, viscose rayon and lyocell may be used. Modified cellulosic fibers are generally are composed of derivatives of cellulose formed by substitution of appropriate radicals (e.g., carboxyl, alkyl, acetate, nitrate, etc.) for hydroxyl groups along the carbon chain.
As used herein, the term “pulp” refers to fibers from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse.
As used herein, the term “deformed” means displaced out of the x-y plane.
In the following detailed description of the present invention, reference is made to the accompanying drawings which form a part hereof, and which show by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that mechanical, procedural, and other changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
In the present invention, the substrate of the wiping cloth has a plurality of apertures which are surrounded by three-dimensional projections. To gain a better understanding of the present invention attention is directed to
To gain a better understanding of the three-dimensional projections 19, attention is directed to
The apertures 14 in the substrate 12 extend through the substrate from the bottom surface 22 and through the top surface 20. The apertures may be uniform in size or may be tapered. As is shown in
The wiping cloth 10 of the present invention generally contains a substrate 12 which is least partially prepared from a thermoplastic polymer. Generally, the substrate 12 will contain fibers and some of the fibers must be fibers prepared from a thermoplastic polymer. The substrate 12 may be absorbent to liquids and/or have ability to capture and retain liquids that come into contact with the substrate 12. Alternatively, the wiping cloth 10 of the present invention may be such that the substrate 12 is able to capture and retain particles, such as dirt, dust and the like. Suitable substrates for the wiping cloth of the present invention can include a nonwoven fabric, woven fabric, knit fabric, or laminates of these materials. Materials and processes suitable for forming such wiping cloth are generally well known to those skilled in the art.
For instance, some examples of nonwoven fabrics that may used in the present invention include, but are not limited to, spunbonded webs, meltblown webs, bonded carded webs, air-laid webs, coform webs, spunlace nonwoven web, hydraulically entangled webs, and the like. In each case, at least one of the fibers used to prepare the nonwoven fabric is a thermoplastic material containing fiber. In addition, nonwoven fabrics may be a combination of thermoplastic fibers and natural fibers, such as, for example, cellulosic fibers (softwood pulp, hardwood pulp, thermomechanical pulp, etc.). Generally, from the standpoint of cost and desired properties, the substrate for the wiping cloth is a nonwoven fabric.
If desired, the nonwoven fabric may also be bonded using techniques well known in the art to improve the durability, strength, hand, aesthetics, texture, and/or other properties of the fabric. For instance, the nonwoven fabric can be thermally (e.g., pattern bonded, through-air dried), ultrasonically, adhesively and/or mechanically (e.g. needled) bonded. For instance, various pattern bonding techniques are described in U.S. Pat. No. 3,855,046 to Hansen; U.S. Pat. No. 5,620,779 to Levy, et al.; U.S. Pat. No. 5,962,112 to Haynes, et al.; U.S. Pat. No. 6,093,665 to Sayovitz, et al.; U.S. Design Pat. No. 428,267 to Romano, et al.; and U.S. Design Pat. No. 390,708 to Brown, which are incorporated herein in their entirety by reference thereto for all purposes.
The nonwoven fabric can be bonded by continuous seams or patterns. As additional examples, the nonwoven fabric can be bonded along the periphery of the sheet or simply across the width or cross-direction (CD) of the web adjacent the edges. Other bond techniques, such as a combination of thermal bonding and latex impregnation, may also be used. Alternatively and/or additionally, a resin, latex or adhesive may be applied to the nonwoven fabric by, for example, spraying or printing, and dried to provide the desired bonding. Still other suitable bonding techniques may be described in U.S. Pat. No. 5,284,703 to Everhart, et al., U.S. Pat. No. 6,103,061 to Anderson, et al., and U.S. Pat. No. 6,197,404 to Varona, which are incorporated herein in its entirety by reference thereto for all purposes.
In another embodiment, the substrate of the wiping cloth is formed from a spunbonded web containing monocomponent and/or multicomponent fibers. Multicomponent fibers are fibers that have been formed from at least two polymer components. Such fibers are usually extruded from separate extruders but spun together to form one fiber. The polymers of the respective components are usually different from each other although multicomponent fibers may include separate components of similar or identical polymeric materials. The individual components are typically arranged in substantially constantly positioned distinct zones across the cross-section of the fiber and extend substantially along the entire length of the fiber. The configuration of such fibers may be, for example, a side-by-side arrangement, a pie arrangement, or any other arrangement.
When utilized, multicomponent fibers can also be splittable. In fabricating multicomponent fibers that are splittable, the individual segments that collectively form the unitary multicomponent fiber are contiguous along the longitudinal direction of the multicomponent fiber in a manner such that one or more segments form part of the outer surface of the unitary multicomponent fiber. In other words, one or more segments are exposed along the outer perimeter of the multicomponent fiber. For example, splittable multicomponent fibers and methods for making such fibers are described in U.S. Pat. No. 5,935,883 to Pike and U.S. Pat. No. 6,200,669 to Marmon, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
The substrate can also contain a coform material. The term “coform material” generally refers to composite materials comprising a mixture or stabilized matrix of thermoplastic fibers and a second non-thermoplastic material. As an example, coform materials may be made by a process in which at least one meltblown die head is arranged near a chute through which other materials are added to the web while it is forming. Such other materials may include, but are not limited to, fibrous organic materials such as woody or non-woody pulp such as cotton, rayon, recycled paper, pulp fluff and also superabsorbent particles, inorganic absorbent materials, treated polymeric staple fibers and the like. Some examples of such coform materials are disclosed in U.S. Pat. No. 4,100,324 to Anderson, et al.; U.S. Pat. No. 5,284,703 to Everhart, et al.; and U.S. Pat. No. 5,350,624 to Georger, et al.; which are incorporated herein in their entirety by reference thereto for all purposes.
In addition, the wiping cloth can also be formed from a material that is imparted with texture one or more surfaces. For instances, in some embodiments, the wiping cloth can be formed from a dual-textured spunbond or meltblown material, such as described in U.S. Pat. No. 4,659,609 to Lamers, et al. and U.S. Pat. No. 4,833,003 to Win, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
In one particular embodiment of the present invention, the wiping cloth is formed from a hydroentangled nonwoven fabric. Hydroentangling processes and hydroentangled composite webs containing various combinations of different fibers are known in the art. A typical hydroentangling process utilizes high pressure jet streams of water to entangle staple fibers and/or substantially continuous fibers to form a highly entangled consolidated fibrous structure, e.g., a nonwoven fabric. Hydroentangled nonwoven fabrics of staple length fibers and substantially continuous fibers are disclosed, for example, in U.S. Pat. No. 3,494,821 to Evans and U.S. Pat. No. 4,144,370 to Bouolton, which are incorporated herein in their entirety by reference thereto for all purposes. Hydroentangled composite nonwoven fabrics of a continuous filament nonwoven web and a pulp layer are disclosed, for example, in U.S. Pat. No. 5,284,703 to Everhart, et al. and U.S. Pat. No. 6,315,864 to Anderson, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of these nonwoven fabrics, hydroentangled nonwoven webs with staple fibers entangled with thermoplastic fibers is especially suited as the substrate. In one particular example of a hydroentangled nonwoven web, the staple fibers are hydraulically entangled with substantially continuous thermoplastic fibers. The staple fibers may be cellulosic staple fibers, non-cellulosic staple fibers or a mixture thereof. Suitable non-cellulosic staple fibers includes thermoplastic staple fibers, such as polyolefin staple fibers, polyester staple fibers, nylon staple fibers, polyvinyl acetate staple fibers, and mixtures thereof. Other suitable thermoplastic staple fibers may be prepared from the thermoplastic materials disclosed below. Suitable cellulosic staple fibers include for example, pulp, thermomechanical pulp, synthetic cellulosic fibers, modified cellulosic fibers, and the like. Cellulosic fibers may be obtained from secondary or recycled sources. Some examples of suitable cellulosic fiber sources include virgin wood fibers, such as thermomechanical, bleached and unbleached softwood and hardwood pulps. Secondary or recycled cellulosic fibers may be obtained from office waste, newsprint, brown paper stock, paperboard scrap, etc., may also be used. Further, vegetable fibers, such as abaca, flax, milkweed, cotton, modified cotton, cotton linters, can also be used as the cellulosic fibers. In addition, synthetic cellulosic fibers such as, for example, rayon and viscose rayon may be used. Modified cellulosic fibers are generally are composed of derivatives of cellulose formed by substitution of appropriate radicals (e.g., carboxyl, alkyl, acetate, nitrate, etc.) for hydroxyl groups along the carbon chain.
One particularly suitable hydroentangled nonwoven web is a nonwoven web composite of polypropylene spunbond fibers, which are substantially continuous fibers, having pulp fibers hydraulically entangled with the spunbond fibers. Another particularly suitable hydroentangled nonwoven web is a nonwoven web composite of polypropylene spunbond fibers having a mixture of cellulosic and non-cellulosic staple fibers hydraulically entangled with the spunbond fibers.
The substrate of the present invention may be prepared solely from thermoplastic fibers or may contain both thermoplastic fibers and non-thermoplastic fibers. Generally, when the substrate contains both thermoplastic fibers and non-thermoplastic fibers, the thermoplastic fibers make up from about 10% to about 90%, by weight of the substrate. In a particular embodiment, the substrate contains between about 10% and about 30%, by weight, thermoplastic fibers.
Generally, the nonwoven substrate 12 will have a basis weight in the range of about 17 gsm (grams per square meter) to about 200 gsm, more typically, between about 33 gsm to about 200 gsm. The actual basis weight can be higher than 200 gsm for some wiping application, but for the most wiping applications, the basis weight will be in the 33 gsm to 150 gsm range. This will produce a wiper having suitable absorbency without being too costly.
The thermoplastic materials or fibers making-up at least a portion of the substrate 12 can essentially be any thermoplastic polymer. Suitable thermoplastic polymers include polyolefins, polyesters, polyamides, polyurethanes, polyvinylchloride, polytetrafluoroethylene, polystyrene, polyethylene terephthalate, biodegradable polymers such as polylactic acid and copolymers and blends thereof. Suitable polyolefins include polyethylene, e.g., high density polyethylene, medium density polyethylene, low density polyethylene and linear low density polyethylene; polypropylene, e.g., isotactic polypropylene, syndiotactic polypropylene, blends of isotactic polypropylene and atactic polypropylene, and blends thereof; polybutylene, e.g., poly(1-butene) and poly(2-butene); polypentene, e.g., poly(1-pentene) and poly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl 1-pentene); and copolymers and blends thereof. Suitable copolymers include random and block copolymers prepared from two or more different unsaturated olefin monomers, such as ethylene/propylene and ethylene/butylene copolymers. Suitable polyamides include nylon 6, nylon 6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, nylon 6/12, nylon 12/12, copolymers of caprolactam and alkylene oxide diamine, and the like, as well as blends and copolymers thereof. Suitable polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polytetramethylene terephthalate, polycyclohexylene-1,4-dimethylene terephthalate, and isophthalate copolymers thereof, as well as blends thereof. These thermoplastic polymers can be used to prepare both substantially continuous fibers and staple fibers, in accordance with the present invention.
Forming apertures in substrates may be accomplished by many different methods. In the present invention, the apertures are formed by a hot pin aperturing process. Hot pin aperturing uses pins that are heated to aperture the substrate. Generally speaking, in hot pin aperturing, the substrate is passed through a nip formed by a heated pin roll and a corresponding apertured roller or counter roller. In this arrangement of a pin roll and an aperture roller, the pins on the pin roller are heated.
To gain a better understanding of the aperturing process, attention is directed to
As shown in
The pin roll 50 and counter roll 52 may be manufactured of rigid material and are mounted on an adjustable chassis (not shown) to allow modification of the distance between the rolls. In particular, pin roll 50 is generally manufactured of metallic material and pins 54 are preferably manufactured of a metallic or ceramic material. As shown in
Generally, the recesses 56 in the counter roller 52 are larger than pins 54 and the recesses 56 may be shaped. This allows the pins 54 to displace the substrate 12 into the recesses 56, thereby providing the three-dimensional projection 19 extending out of the plane 18 of the substrate 12, as is shown in
In an alternative method of making the substrate 12 for the wiping cloth 10 of the present invention, the counter roller 52 may be a roller made from a pliable material and is devoid of recesses. The pliable material allows the pins 54 to contact the counter roller and, when the pin ceases to contact the counter roller, the pliable material allows the counter roller 52 to recover to its original state. Suitable pliable materials included materials such as felt, rubber and other similar materials which will recover to its original state when the pins are moved out of contact with the counter roller.
In the present invention, the pins 54 are heated. The pins 54 are generally heated to a temperature sufficiently high enough to soften the thermoplastic fibers and allow deformation of the thermoplastic fibers. However, the temperature the pins 54 are heated must be below the melting point of the thermoplastic polymer component used to make the thermoplastic fiber. This is because it is not desirable in the present invention to fuse the thermoplastic fibers together. In the present invention, it is desirable that the three-dimensional projections 19 extending out of the plane 18 of the substrates are unconsolidated and less densified than the area 15 of the substrate without apertures and without three-dimensional projections. The actual temperature must be carefully selected depending on the thermoplastic polymer component used to make the thermoplastic fibers. If multicomponent thermoplastic fibers are used, the lowest melting point thermoplastic polymer component of the thermoplastic fibers will be used to set the temperature of the pins 54. As an example, if the thermoplastic polymer component of the thermoplastic fibers is polypropylene, which has a melting point of about 160° C., the pins will be heated to a temperature up to about 150° C. or below. Generally, the pins will be heated to a temperature which is at least 10° C. below the melting point of the thermoplastic polymer component of the thermoplastic fibers. More typically, the temperature of the pins 55 will be set at a temperature which is at least 20° C. below the melting point of the thermoplastic polymer. Again, it is pointed out the pin temperature is selected so that the pins 55 will soften the thermoplastic polymer and will allow deformation of the thermoplastic polymer fibers present in the substrate 12, not to melt and bond the thermoplastic fibers to one another. In one particular embodiment of the present invention, the thermoplastic polymer is polypropylene and the pins were heated to a temperature between about 100° C. to about 120° C.
In operation of the pin roller 50 and the counter roller 52 during the aperturing process, the surface 51 of the pin roller 50, and the surface 53 of the counter 52 roller may contact one another during aperturing. As such, the surface 51 of the pin roller 50 and the surface 53 of the counter roller 52 will place pressure on the substrate 12. This pressure may compress the substrate between the apertures and the three-dimensional projections. Alternatively, the pin roller 50 and the counter roller may be operated such that the surfaces 51 and 53 two rollers do not contact one another, as is shown in
Other factors to consider in determining the optimum process conditions for forming apertures/three-dimensional projections include, the speed of the rollers, the dwell time the pins contact the substrate and the substrate itself. It is within the skill of those skilled in the art to select the optimum process conditions for the particular substrate being formed with apertures and three-dimensional projections. In addition, the aperturing process may be an in-line process, i.e., on the production line of the nonwoven web, or may be completed in an off-line process. In an off-line process, typically the nonwoven web to be apertured may fed to the aperturing process from a roll of the nonwoven material.
Referring to
The apertures 14 and three-dimensional projections 19, may be formed in the substrate at various densities, depending on the features desired in the resulting wiping cloth. Typically, the aperture/three-dimensional projection density will be from about 1 aperture/three-dimensional projection per square centimeter to about 50 apertures/three-dimensional projections per square centimeter. More typically, there are between about 5 apertures/three-dimensional projections per square centimeter to about 20 apertures/three-dimensional projections per square centimeter. The number of apertures/three-dimensional projections is dependent on the size of the pins 54. Generally, the pins have a diameter of about 1 mm to about 7 mm at its widest diameter and more typically in the range of about 1.2 mm to about 4.0 mm at the widest diameter. In addition to cylindrical pins, the pens could be shaped in different shapes, such as squares, hexagons, octagons and the like.
In the present invention, the apertures/three-dimensional projections may be present in some areas of the substrate and not in others. The apertures/three-dimensional projections may be present in a geometric pattern, in which all of the apertures/three-dimensional projections are evenly spaced from one another or the apertures/three-dimensional projections may be placed on the substrate in aesthetically pleasing patterns which form shapes, objects, logos and the like. Examples of patterns are shown in
Referring back to
In addition, each aperture 14 may have a general opening size or diameter size which corresponds to the diameter of the pins 54. Generally, at the top of each three-dimensional projection 19 on the substrate 12, the size or diameter of the aperture will be similar to the diameter of the pins used to create the apertures or the diameter of the portion of the pin 54 which contacts and pierces the substrate 12. On the second side 13 of the substrate 12, the size or diameter of the aperture will generally be larger than the size of the aperture 14 at the top of the three-dimensional projection 19. This is because the pins 54 do not generally aperture the substrate 12 solely in a vertical position with respect to the substrate, but will start to contact the substrate 12 at an angle less than 90° and will exit from the substrate at an angle less than 90° relative to the substrate. This can be seen in
In another embodiment of the present invention, both the first side 11 and the second side 13 of the substrate 11 may contain raised portions 16, 16′ which form three-dimensional projections 19, 19′. In the regard, attention is directed to
To form three-dimensional projections on both sides 11 and 13 of the substrate 12, the substrate 12 may be run through the apparatus shown in
To gain a better understanding of the structure of the apertures 14 and three-dimensional projections 19, attention is directed to
It is also pointed out that
The present invention provides a wiping cloth which has unique tactile properties, enhance wiping performance for wiping both wet and dry substrates. The wiping cloth also has a visual appearance which will appeal to a user by retaining its shape and function before and during use in both a wet state and a dry state. In addition, the wiping cloth of the present invention is softer and pleasing to the touch as compared to unapertured wiping cloths.
Another advantage of the wiping cloths of the present invention is the three-dimensional projections on only one side of the wiping cloth substrate results in a wiping cloth having two-sidedness. The side with the three-dimensional projections which is rougher and imparts a scrubbing ability to the wiping cloth and the side without the three-dimensional projections is softer, which is more of a wiping side of the wiping cloth. Having the three-dimensional projections improves the ability of the wiping cloth to pick-up and retain particles.
To demonstrate the advantages and properties of wiping cloths within the scope the present invention, the following Examples and comparative controls have been completed.
In this Example a hydroentangled nonwoven web having a basis weight of about 64 gsm is used as the wiping cloth As a control, a WYPALL X60 wiper available from Kimberly-Clark Global Sales, LLC, having offices in Roswell, Ga. was used. In the control and in each sample, the wiping cloth substrate is a polypropylene spunbond nonwoven web having a basis weight of about 13 gsm which is hydroentangled with pulp fibers. After hydroentangling the wiping cloth substrate has a basis weight around 64 gsm. The actual basis weight of each sample is shown in TABLE 1.
The apertured samples are apertured in different pin densities and different pin penetration. The hydroentangled substrate is apertured using a pin density of 7 pins per square centimeter, 11 pins per square centimeter or 18 pins per square centimeter. The diameter of the pins for each pin density is different. 7 pins per square centimeter uses pins having a diameter of 3.1 mm, 11 pins per square centimeter uses pins having a diameter of 2.5 mm and 18 pins per square centimeter uses pins having a diameter of 1.4 mm. In each case, the apertures are evenly spaced on the substrate. Also, Samples D and E use patterns of aperture pins. The pattern in Sample D is shown in
Test Procedure
Oil & Water Capacity:
The absorptive capacity refers to the capacity of a material to absorb liquid over a period of time and is related to the total amount of liquid held by a material at its point of saturation. Absorptive capacity is determined by measuring the increase in the weight of a material sample resulting from the absorption of a liquid. Absorptive capacity for both water and mineral oil were tested. The test procedure is as follows and the test is completed with the liquid at 23° C.±3° C. The liquid is distilled water and mineral oil. The mineral oil is white mineral (paraffin) having a +30 Saybolt color, NF grade 80-90 Saybolt Universal viscosity. The test procedure is as follows:
5. Absorptive capacity may be expressed, in percent, as the weight of liquid absorbed divided by the weight of the sample by the following equation: Total Absorptive Capacity=[(Saturated Sample Weight-Sample Weight)/Sample Weight]×100
Caliper Test
The results for each sample and test are shown in TABLE 1.
As can be seen from TABLE 1, aperturing increases the bulk of the samples and increases the capacity of the wiping cloth to absorb both water and mineral oil. As a result, the aperture substrate is very effective as wiping cloth. It is also noted that projections created by the apertures substantially retained their shape when wetted with both water and mineral oil.
Further testing of the wiping cloths of the present invention was carried out. Samples B-1 and B-2 are the same samples as in Example 1. The cleaning ability of these wiping cloths were compared to three commercially available wiping cloths. The three commercially available wiping cloths are all flat apertured wiping cloths. The bonded carded web (BCW) is a WYPALL Workforce Xtra Food Service Towel, 70 gsm, which is available from Kimberly-Clark Global Sales, LLC, having Offices in Roswell, Ga. The spunlace is Saniwork Deluxe Food Service Towel that has been apertured hydraulically during the hydroentangling process and is available from Hospeco, having offices in Cleveland, Ohio. The wiping cloths are used in wiping test as both dry wiping and wet wiping. In this example, modified gear grease (MGG) and modified engine oil (MEO) are used. Modified gear grease is Sta-Lube Wheel Bearing Grease mixed with 4% carbon black, by weight. The modified engine oil is Valvoline VRL Racing Motor Oil SAE50 mixed with 4% carbon black, by weight. The dry and wet wiping test are performed using BYK-Gardner Abrasion Rub Tester following the test procedure outlined below.
Dry Wiping Test.
1. Armstrong Excelon White Vinyl Composition Flooring Tiles are cut into 3″×12″ pieces and the test tiles are labeled according to the test samples.
2. To ensure that the tiles are clean, the test tiles may be wiped with a multipurpose cleaner. After cleaning, the weight of each test tile is determined.
3. The tiles are next soiled with oil or grease and the amount of soiling component is recorded. For oil generally 0.5-0.55 grams is placed on the tile. For grease, 0.7 to 0.75 grams is placed on the tile. Oil is placed using a large tipped pipette and is applied in the center of the tile. The oil is spread uniformly on the tile with a foam tipped brush. In the case of grease, a micro spatula is used to spread the grease onto the tile. A foam tipped brush is used to uniformly spread the grease on the tile.
4. Each tile is reweighed to determine the weight of the grease or oil on the tile.
5. The wiping cloth to be tested is wrapped around a carpeted wood block, with the side to be tested facing outward such that the wiping cloth is single ply on the carpeted side of the testing block and is held in place with a rubberband.
6. The soiled tile is placed into a slot on a Gardner test pan.
7. The padded block with the wiping cloth is placed into the Gardner holder with the carpeted side of the block facing downward with the wiping cloth contacting the soiled tile.
8. The tester is run for 25 cycles, which is 50 passes. Each cycle is back and forth across the soiled tile.
9. The test is stopped. The tile is removed and the cleaned tile is again weighed to determine the amount of the grease/oil was removed by the wiping cloth.
10. The percentage of the soil removed is determined by the following equation: % soil removed=soil removed by the wiper/total soil on tile before wiping.
Wet Wiping Test
1. The same procedure is repeated except in step 7, 2 grams of the following cleaning fluid shown in TABLE 2 is applied to the wiper in the block before it is replaced into the holder.
The results of the wiping test are shown in Table 3. In addition a 5 cycle test was completed with modified gear grease to simulate actual wiping that would normally occur in cleaning a substrate. Both sides of the wiping cloth are tested with the smooth side being the side without projections and the rough side being the side with the three-dimensional projections.
As can be seen in Table 3, the wiping cloths of the present invention are very effective in both wet and dry wiping as compared to the commercially available wipers with apertures.
Although the present invention has been described with reference to various embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. As such, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is the appended claims, including all equivalents thereof, which are intended to define the scope of the invention.
