MXPA97008156A - Disposable paper products with indicated media - Google Patents

Abstract

l. Paper products, such as paper towels, are provided, are indicator means, which is placed on said disposable paper product with a discontinuous pattern or discontinuous / continuous combination. The indicating means provides a signal that is visually recognized to a user who wishes the properties of the disposable paper product to be retained, even after the disposable paper product has been moistened with a substantially transparent aqueous liquid. The gray scale of humidity, which marks the difference of the paper product of the present invention, is at least about 64 gray scale units, when the disposable paper product is moistened with a substantially transparent aqueous liquid.

Description

DISPOSABLE PAPER PRODUCTS WITH INDICATOR MEDIA BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to disposable paper products. In particular, the present invention relates to the provision of said disposable paper products, with indicating means that the desirable properties of the disposable paper product are retained when the paper product is moistened with a substantially transparent aqueous liquid. BACKGROUND OF THE INVENTION Disposable products, such as facial tissues, toilet paper for the bathroom, paper towels and the like, are usually made from one or more paper rolls. If the products are going to perform the tasks for which they are made, the paper reels from which said paper products are formed must exhibit certain physical characteristics. Among these characteristics, the most important are the resistance, the softness and the absorbency. Resistance is the ability of a paper coil to maintain its physical integrity during its use. The softness is the pleasant sensation to the touch, which is perceived by the user when he crushes the paper product in his hand, and when he puts several parts of his body in contact with the paper reel. Softness, generally increases to the extent in which the rigidity decreases. Absorbency is the characteristic of toilet paper, which allows to take and retain liquids. Normally, the softness and / or absorbency of a paper roll is increased at the expense of paper strength. Accordingly, methods for papermaking have been developed, as an attempt to provide soft and absorbent disposable paper products, which have desirable strength characteristics. U.S. Patent No. 3,301,746, issued to Sanford and Associates, discloses a paper roll, which is subjected to prior thermal drying, with an air drying system. Subsequently, the parts of the coil are printed with a pattern of knot material in the dryer drum, in order to produce a paper having two different regions with different fiber densities. Drying through air usually improves both the softness and the absorbency of a paper roll. Disposable paper products, made using such paper in the form of a substrate, have great commercial success. U.S. Patent No. 4,637,859, issued to Trokhan, also describes a paper having two distinct regions. The first, is the mesh region, forms an essentially continuous pattern. The other region comprises a plurality of separate domes. The mesh region completely encloses the domed regions and isolates one dome from the other. The mesh region has a relatively high density while the domes have a relatively low density. The paper according to U.S. Patent No. 4,637,859 exhibits good absorbency, softness, tensile strength, blowout resistance and bulk. Depending on the pattern selected for the mesh region, the paper also has the ability to stretch in the direction of the machine, in the transverse direction of the machine, and in intermediate directions even in the absence of crackling. The role of this time has enjoyed great commercial success, as a substrate to be used in the production of paper towels and toilet paper. An alternative method for improving the properties of disposable paper products has been the incorporation of non-cellulosic materials into the structure of the disposable paper product. For example, the use of materials to add resistance to disposable paper products is well known in the art. Also, non-cellulosic fibers have been added to the composition for the papermaking machine used to produce the substrate of the disposable paper product. Nevertheless, methods of this type also generates a cost, such as loss of softness or loss of absorbency. Generally, in the art, only such methods have been used to cover some very specific needs, where the benefit obtained counteracts the cost paid. Frequently, disposable paper products, particularly paper towels, comprise a laminate of two or more sheets. Disposable products comprising more than one sheet have the desired properties of increased volume, increased absorbency and increased strength per unit area of the product compared to products consisting of a single sheet. US Patent No. 3,414,459 to Wells discloses a laminated paper product which is formed by recording identical raised patterns of protuberances on two sheets of paper and bonding the spliced distant surfaces of the protuberances with adhesives in order to form the laminate. Laminates of this type have enjoyed considerable commercial success, particularly as disposable paper towels. U.S. Patent No. 4,978,565 issued to Pigneul et al. Discloses laminated paper products that are adhesively bonded, at least partially, by protruding elements. It is said that the elements are placed according to some lines or combinations of lines which reproduce spaced sets. It is also said that laminates of this type provide a satisfactory bulky texture without a reduction in mechanical strength, which is said to come from the engraving of the protuberances at a high density. U.S. Patent No. 5, 294,475 issued to McNeil discloses laminated prints of paper consisting of two sheets, in which each of the engraved sites of one sheet are attached with adhesives to the region of the other sheet that is not engraved. Laminates of this type have a similar appearance to that of a high-quality quilted fabric, and a relatively thick gauge, as well as a pleasing pattern in regard to aesthetics, without sacrificing other desirable qualities, such as softness, absorbance and the strength of the bond between the laminate. However, the art has worked continuously to improve the properties of disposable paper products, trying not to lose the other properties, the users of such articles, often find it difficult to recognize such improvements. For example, when a disposable paper product recorded from the present art is saturated with water, the entire pattern of appearance originated by said engravings disappears in an essential way. This means that even if the engraving pattern was chosen to preserve the physical properties of the unrecorded paper to the greatest extent possible, a user of such a product would not have an easily discernible signal that the product contains such benefits. Therefore, it is an object of the present invention to provide disposable paper products, such as paper towels, with an easily recognizable signal that the article has desirable physical properties, both when the article is dry, and when in a particular manner. , the article is moistened with a substantially transparent aqueous liquid. It is another object of the present invention to provide laminated disposable products, such that, when the disposable laminated paper is wet, the difference that exists in the visual appearance of the paper rolls comprising the laminate and those of a indicating means, be notorious enough SUMMARY OF THE INVENTION The present invention is a disposable paper product which comprises at least one paper sheet with a relatively low basis weight. The disposable paper product is additionally provided with a indicating means, which is placed on the sheet in a pattern. The indicator means provides the user of the paper product with a visual signal indicating that the desirable properties of the towel are maintained, even when the product is moistened with a substantially transparent aqueous liquid. The visual signal becomes especially noticeable when the disposable paper product of the present invention is moistened with a substantially transparent aqueous liquid. The indicator means can be further characterized, by the difference of humidity in the gray scale, as a measure using image analysis techniques, between those parts of the outer surfaces of the paper product, which are provided with the means indicators, and the parts of the interior surfaces that are not provided with said indicator means. This difference only becomes important, when the laminated paper towel of the present invention is moistened with a substantially transparent aqueous liquid. A preferred embodiment of the present invention is a laminated paper towel, which comprises two sheets. In the preferred embodiment, the indicator means comprises an opacifying agent, which is added to the laminating adhesive means and is placed on the sheet in a pattern comprising either separate elements or a pattern combining the separate elements with the continuous elements . Alternative embodiments of the present invention include disposable paper products, which comprise a single sheet or sheets, comprising more than the laminates, which are provided with a display means as described above. The indicator means may comprise any material that provides the visual signal as a requirement, at the time that the toilet paper product is moistened with a substantially transparent aqueous liquid. Alternative, non-limiting examples of indicator means include printed indicator means, fibers having a refractive index when wet, which is different at the refractive index of the wet cellulosic fibers, and means to prevent wetting in some parts of the body. Toilet paper product.

BRIEF DESCRIPTION OF THE DRAWINGS Although the specification concludes with the claims that point in particular and claim in distinctive form the present invention, we believe that it will be better understood by reading the detailed description of the invention that follows, taken in conjunction with the accompanying drawings, in which are provided the same reference for similar components, and: Figure 1 is a fragmentary plan view from the top, of a preferred embodiment of the present invention, in which is illustrated a disposable paper product, in partially cut form which reveals the lower structure. Figure 2 is an elongated sectional view, taken along lines 2-2, of the disposable paper product of the present invention. Figure 3 is a photographic plan view of the disposable paper product of the present invention, shown in its dry condition. Figure 4 is a photographic image in plan view of the disposable paper product of Figure 3, in its wet condition. Figure 5 is a photographic image of a disposable paper product, similar to the disposable paper product of the present invention, except that it does not comprise a display means, in its wet condition. Figure 6 is a schematic perspective view, which shows the distribution of an image analysis apparatus, which is used to evaluate the disposable paper product of the present invention.

DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment, the present invention comprises a disposable paper product. which is a laminate of at least two sheets of paper. These products have been used as paper towels, toilet paper for the bathroom, and facial tissues. Preferably, this paper is thin paper with a relatively low basis weight, which is commonly known as toilet paper. More preferably, the paper comprises two regions, one of continuous mesh and one with a plurality of domes, as described in US Patent No. 4,637,859, which was mentioned above and is incorporated herein by reference. These sheets are joined using methods known in the art. For example, the sheet can be joined, by the process described in any of the aforementioned US Patents No. 3,414,459 or 5,294,475, which are also incorporated herein by reference. Preferably, the sheet is provided with etched areas and the etched areas of a sheet are attached by adhesive means to the non-engraved regions of another sheet, using the method commonly known as series engraving, as described, for example, in FIG. U.S. Patent No. 5,294,475. The laminate of the present invention is additionally provided with a indicating means placed on at least one of the sheets, in a pattern of separate elements or in a pattern comprising a combination of separate and continuous elements. This indicator means, when the laminate is moistened with a substantially transparent aqueous liquid, provides a signal indicating that the laminate has maintained the desirable properties, even after it has been moistened. It should be noted, that a laminated structure is not necessarily for the indicating means to provide a signal indicating that the disposable paper product has retained its desirable properties after it has been moistened with a substantially transparent aqueous liquid. Therefore, it is contemplated that the present invention includes paper structures, wherein a single sheet of paper is provided with a display means, such as the one described above. Referring to Figure 1, a preferred embodiment of the present invention comprises a laminated paper towel 20. The foregoing is not intended to limit the present invention to exclusively paper towel modalities. Paper products comprising one or more layers of toilet paper, such as toilet tissue for bathing and facial tissues, are also considered to be within the scope of the present invention. In accordance with the present invention, the laminated paper towel 20 comprises two sheets 20T and 20B, in a face-to-face relationship. Each of the sheets 20T and 20B has two different zones, a continuously unregistered region 24 and a zone with a separate engraving, which generally project towards the opposite sheet 20B or 20T respectively, and preferably orthogonal to the same. The lamination adhesive means 27 is applied to the relatively distant ends 23 of at least some of the engraved areas 22 of one of the sheets 20T and / or 20B, to attach adhesively to the surfaces of the cover of the sheets 20T and 20B. The laminated paper towel 20 additionally has two opposite surfaces which are oriented outwards 30 and 32. The term "outward facing surface", as used in the present description, refers to the surface of each of the sheets 20T and 20B, which is opposite the surface of the sheet 20T or 20B, and which is adhesively bonded to the sheet of the cover 20B or 20T. The surfaces of the outer cover 30 and 32 are those surfaces of the laminated paper towel 20, which are in view of a user. Each of the zones 22 and 24 of each sheet 20T or 20B is composed of approximate fibers by means of linear elements. The cellulosic fibers that are components of the laminated paper towel 20, have a relatively long dimension (along the longitudinal axis of the fiber), compared with the other two relatively small dimensions (mutually perpendicular to each other, and placing both in radial form and perpendicular to the longitudinal axis of the fiber), so that the linearity is approximate. Although microscopic examination of the fibers may reveal that two other dimensions are small, compared to the main dimension of the fibers, these other two small dimensions do not need to be substantially equivalent or constant along the entire length of the axis of the fiber. fiber. It is only important that the fiber has the ability to bend around the axis. that has the ability to bind with the other fibers and that is distributed by a liquid vehicle or by means of air. The fibers of which the laminated paper towel 20 is formed can be of synthetic origin, such as polyolefin or polyester; preferably cellulosic fibers, such as cotton yarn, rayon or bagasse; and more preferably wood pulp fibers, such as soft woods (gymnosperms or conifers) or hardwoods (angiosperms or decadents). A rolled paper towel 20. as used in the present description, is considered "cellulosic", if the laminated paper towel 20 comprises at least about 50% by weight, or at least about 50% by volume of cellulosic fibers, including but not limited to those fibers indicated above. It has been discovered that a cellulose mixture of wood pulp fibers, comprising softwood fibers having a length of from about 2.0 to about 4.5 millimeters and a diameter of from about 25 to about 50 microns and hardwood fibers having a length of less than about 1.7 millimeters and a diameter of from about 12 to about 25 microns, works well for the laminated paper towels 20, which are detailed in the present description.

If the wood pulp fibers are selected for the laminated paper towel 20, the fibers can be produced by any pulping process, including chemical processes such as sulfite, sulphate and soda processes; and mechanical processes such as ground stone wood. Alternatively, the fibers can be produced by combinations of chemical and mechanical processes or can be recycled. The type, combination, and processing of the fibers used are not critical to the present invention. The hardwood and softwood fibers may have layers throughout the thickness of the laminated paper towel 20, or they may be mixed homogeneously therein. According to the present invention, a laminated paper towel 20 is two-dimensional and flat in macroscopic form, although not necessarily in a flat form. The laminated paper towel 20 has some degree of thickness in the third dimension. However, the third dimension is relatively small, compared to the first two real dimensions. In accordance with the present invention, the laminated paper towel 20 comprises a laminate of two individually shaped sheets 20T and 20B. A "sheet" is taken from the forming element of the papermaking machine and in the form of a single sheet, which has a thickness prior to the drying process, which does not change unless the fibers are added or removed of the sheet. The basis weight of each of the sheets 20T and 20B may be in the range of from about 9 pounds per 3000 square feet to about 30 pounds per 3000 square feet, preferably from about 12 pounds per 3000 square feet to about 20 pounds by 3000 square feet. Each of the sheets 20T or 20B is attached to the other sheet 20B or 20T. It is understood that each of the sheets 20T or 20B may be attached directly to the opposite sheet 20B or 20T, or within a preferred embodiment of the present invention, which comprises three or more sheets, may be connected through a intermediate layer or layers, if desired, can be placed on the inside between the sheet 20T and 20B. As shown more clearly in Figure 2, each of the sheets 20T and 20B of the laminated paper towel 20 is joined to the other sheet 20B and 20T in the engraved areas 22. In particular, the end Relatively distant 23 of each of the engraved areas 22, is projected towards the unrecorded region 24 of the opposite sheet 20T or 20B. Preferably the sheet 20T and 20B are adhesively bonded in the engraved areas 22. More preferably, as also shown in Figure 2, the relatively distant ends 23 of one of the sheets, for example the sheet 20B, are attached in adhesive form to the opposite sheet 20T, in the non-engraved regions 24 thereof. That is, the sheets 20T and 20B are adhesively bonded to the alternately etched zones 22. As shown in Figure 2, the laminating adhesive means 27 is applied to the relatively distant end 23 of each of the layers. engraved areas 22 of the sheet 20B, since each engraved area 22 of the sheet 20B, is adhesively bonded to the unrecorded region 24 of the opposite sheet 20T. This distribution provides a laminated paper towel 20 having two sheets 20T and 20B, wherein the sheet 20T and 20B are joined in the alternately etched regions 22. By joining the sheets 20T and 20B in the alternately etched areas 22 , a good balance is provided between the strength and smoothness in the union of the layers. Alternatively, if additional strength is desired in the bonding of the layer, the sheet 20T and 20B may be adhesively bonded in further engraved areas or, if additional smoothness is desired, the sheet 20T and 20B may be bonded in adhesive form in less recorded areas. Referring again to Figure 1, the engraved areas 22 of the first sheet 20T, are not registered with the engraved areas 22 of the second sheet 20B. This distribution provides the advantage that an affirmative step is taken to adhere the engraved areas 22 of one of the sheets 20T or 20B, to the unrecorded region 24 of the other sheet 20B or 20T. This distribution provides the advantage, which is illustrated in Figure 2, that the space of the unrecorded region 24 of one of the sheets 20T or 20B, which is between the engraved areas 22, is supported approximately at its point half 25, by a recorded area 22 of the other sheet. Additionally, the midpoint 25 of said space is glued by the laminating adhesive means 27, which is present at the relatively distant end 23 of any of the engraved areas 22, for which said laminating adhesive means is applied. Of course, one skilled in the art will recognize that the recorded areas 22 and the unrecorded region 24, can be distributed in a pattern such that the recorded areas 22 do not intersect at the midpoint 25 of the region space without record 24 of the other sheet 20T or 20B. However, they are distributed in such a way that the relatively distant end 23 of a recorded area 22 can still have an adhesive means applied thereto, and adhesively bonded to the two sheets 20T and 20B. Additionally, a stamped area 22 is not registered with the mid-point 25 of the space that still supports the space of the non-engraved region 24 of the other sheet 20T or 20B. The engraved areas 22 of each of the sheets 20T or 20B, represent the separated regions with relatively high density, due to the compaction of the fibers, which occurs during the engraving process. The term "etching process", as used in the present description, refers to the process of normal deviation to its plane from a relatively small portion of each of the sheets 20T and 20B, and impacting the projected part of the sheets. against a relatively hard surface for the permanent breakage of fiber to fiber links. The engraving process results in a localized permanent deformation of the engraved area 22, which has already been deflected. The engraving areas 22 project in a normal manner to the plane of the sheet 20T or 20B and to the opposite sheet 20B or 20T. The engraved areas 22 of the laminated paper towel 20 are distributed in a pattern that is not repeated at random, which corresponds to the topography of the apparatus used to create them. Preferably, the tessellations of the pattern are not repeated at random, so that the adjacent engraved areas 22 are juxtaposed cooperatively and advantageously. By not being repeated "at random", the engraved areas 22 are considered to be in a predictable placement, and can occur as a result of the known and predetermined characteristics of the manufacturing process used to produce the laminated papal 20 towel. "repetition", as used in the present description, means a pattern that is formed more than once on a laminated paper towel 20. By being "separated", it means that the adjacent engraved areas 22, are not contiguous. The term "essentially continuous" unrecorded region 24, as used in the present description, means that they extend substantially throughout the fiber structure in one or both of its principal directions. The essentially unbroken recording region 24 has a lower density than that of the engraved areas 22, since the essentially unbroken recording region 24 is not compacted in the etching process. The density of the essentially unbroken region 24, is close to the density of the separate recorded areas 22, before being recorded. For the laminated paper towel 20 illustrated in Figures 1 and 2, the unrecorded region 24 of the laminated paper towel 20, preferably it is in essentially continuous form in two directions within the plane of the laminated paper towel 20. It is not necessary that said directions be in parallel and perpendicular to the ends of the finished product, or be in parallel or perpendicular to the direction of product manufacture. It is only important that the tensile strength be imparted to the laminated paper towel 20 in two directions, since in this way any tension load applied can be accommodated more easily, without the product having premature failures caused by said stress. load of tension. Preferably, at least one direction in a continuous form is parallel to the direction of the stress load that is expected of the finished product, in accordance with this embodiment of the present invention.

An example of an essentially continuous unbroken region 24 is illustrated in Figure 2. Other examples of structures having essentially continuous regions are described in commonly assigned U.S. Patent No. 4,637,859, issued January 20, 1987, issued to Trokhan, and incorporated into the present description as a reference. Interruptions in the essentially continuous continuous recording region 24 are tolerable, as long as such interruptions do not adversely affect the material properties of the laminated paper towel zone 20, but are not preferred. Of course, it will be recognized if the laminated paper towel , as elaborated, is relatively large and if the engraved areas 22 are relatively small compared to the size of the laminated paper towel 20, as they were manufactured, for example, with variations depending on different orders of magnitude, it can it would be difficult to have the ability to predict in absolute form the exact patterns and dispersion, between the recorded areas 22 and the region without recording 24 continuously, or even impossible to guess, if the pattern will still be considered without random repetition. Conversely, if the laminated paper towel 20 is relatively small and the engraved areas 22 are relatively large, as presented to the consumer, it may appear that the pattern does not repeat itself, when in fact, according to the manufacture, it is present a repeating pattern on the larger scale laminated paper towel 20. It is only important, that the engraved areas 22 and the essentially continuous non-engraved region 24, be dispersed in a pattern, such as substantially desired, to produce the operating properties, which make the laminated paper towel 20, suitable for the use that has been proposed. One skilled in the art will appreciate that there may be small transition regions, which have an intermediate density to the density of the recorded areas 22 and to the non-engraved regions 24, and which circumscribe or limit the engraved areas 22. Said transition regions , are a normal and expected artifact of the manufacturing process, and will not be confused with either the recorded areas 22, or the unrecorded region 24. Referring still to Figure 1, the size of the pattern of the recorded areas 22 in the laminated paper towel 20, can vary from about 2 to about 1 1 recorded areas 22 per square centimeter (from 10 to 70 engraved areas 22 per square inch), and preferably, from about 5 to about 8 engraved areas per square centimeter ( from 30 to 50 zones recorded 22 per square inch). The engraved areas 22 can be staggered bilaterally in a pattern having a 45 ° principal axis from the direction of the manufacturing machine, they can be staggered unilaterally, or they can be registered in their position with the adjacent engraved areas. 22. Continuing with the reference of Figure 1, the engraved areas 22 of the first sheet 20T are not in register with the engraved areas 22 of the second sheet 20B. This distribution provides the advantage that an affirmative step is taken to adhere the engraved areas 22 of a sheet 20T or 20B to the non-engraved region 24 of the other sheet 20B or 20T.

Additionally, this distribution provides the advantage, illustrated in Figure 2, that the space of the unrecorded region 24 of a sheet 20T or 20B, which exists between the engraved areas 22, is supported at approximately the midpoint. of the engraved area 22 of the other sheet 20B or 20T. In addition, the midpoint 25 of said space is glued if the laminating adhesive means 27 is present at the relatively distant end 23 of the embossed area 22. Furthermore, the non-engraved region 24 is not compacted by the manufacturing process, just as are the separately recorded zones 22. This difference in compaction between these zones, creates an aesthetically discernible pattern on the laminated paper towel 20. In particular, the pattern creates the appearance similar to a quilted fabric on the laminated paper towel 20, which is shown in Figure 3. It has been found that this appearance similar to a quilted fabric, it will be a clear signal to consumers, that the paper towel having that appearance, also has the desirable combination of strength and softness properties, which are the result of a diligent effort of production, of the art of papermaking .. The sheets 20T and 20B, are joined in the alternately engraved areas 22, using the lamination adhesive means 27. In the preferred embodiment of the laminated paper towel 20, shown in FIG. Figure 1, the lamination adhesive means 27 is applied to the relatively distant ends 23 of the engraved areas 22, of only one of the sheets 20T or 20B. As noted above, if a softer towel 20 is desired, the laminating adhesive 27 may be applied to some of the relatively distant ends 23. Conversely, if greater strength is desired at the bonding of the layers, the lamination adhesive means 27 can also be applied to the relatively distant ends 23 of the engraved areas 22 of the other of the sheets 20B or 20T. The lamination adhesive means 27 is applied by methods well known in the art. Such methods are described in U.S. Patent No. 3,414,459 and in U.S. Patent No. 5,294,475, which are incorporated herein by reference. The lamination adhesive means 27 can comprise any adhesive material known in the art for bonding paper sheets. Such materials include, but are not limited to, hot melt adhesives, preferably pressure sensitive heat melted adhesives.; latex emulsion adhesives; and Water Soluble Adhesives Preferably the laminating adhesive means 27 comprises a water soluble adhesive medium. More preferably, the lamination adhesive means 27 comprises a polyvinyl alcohol resin substantially completely hydrolyzed. A suitable resin is sold under the tradename Evanol 71-30, by E. I. DuPont DeNemours & Co., Wilmington, DE. Preferably, the laminating adhesive means 27 is applied by means of a solution in water having from about 2 to about 8 percent resin solids. More preferably, the water solution has from about 13 to about 6 percent resin solids. The laminated paper towel 20, additionally is provided with a display means 29, to provide the user, a towel structure with a visual signal that the structure of the towel retains its desirable properties, even after the paper towel laminate 20 has been moistened with a substantially transparent aqueous liquid. In the preferred embodiment shown in Figures 1 and 2, the indicator means 29 is juxtaposed with, or preferably placed within, the lamination adhesive means 27. Alternatively, the indicator means 29 may be in separate relation to the medium Laminating adhesive 27. The indicating means 29, provides a visual signal that the laminated paper towel 20 retains its desirable properties when the towel is moistened with a substantially transparent aqueous liquid. The visual signal may also be measured quantitatively, using image analysis techniques, such as a difference in the gray scale level between those portions 34 of the surfaces of the outer cover 30 or 32 that are provided with the indicator means 29, and those portions 36 of the surfaces of the outer cover 30 or 32 that are not provided in this manner when the laminated paper towel 20 is moistened with a substantially transparent aqueous liquid. The indicator means 29, differs from any decorative element that could be applied to the laminated paper towel 20 or incorporated in a single sheet, in which the indicator means 29 would not be noticeable to a user when the laminated paper towel 20 is dry . That is, the difference in the level of gray scale between those portions 34 of the surfaces of the outer cover 30 or 32, which are not provided with the indicator means 29, and those portions 36 of the surfaces of the outer cover 30. and 32, which are not small enough when the laminated paper towel 20 is dry, such that a user would not notice the presence of the indicator means 29. As noted above, the indicator means 29, becomes clearly visible only when the paper towel 20 is moistened with a substantially transparent aqueous liquid. The indicator means 29 may comprise any material which, when applied to the sheets 20T and / or 20B, is not appreciable at the moment when the rolled paper towel 20 is dry, as it becomes visually noticeable, when the laminated paper towel 20 is moistened with a substantially transparent aqueous liquid. Non-limiting examples of said indicator means include: 1) Opaque white inks, which when applied to the 20T and / or 20B sheets, match as closely as possible the color of the fibers comprising the sheet when the fibers are still they are dry, because their opacity is visually distinguishable when the fibers are wetted with a substantially transparent aqueous liquid. 2) Fibers having a refractive index different from that of the cellulosic fibers when wet, can be incorporated into a portion of the composition for the papermaking machine, used to provide the sheets 20T and 20B. Those portions 34 of the sheet provided with said distinct fibers optically would be visually different from those portions 36 which do not have said fibers when the sheets are wetted with a substantially transparent aqueous liquid. 3) Means for preventing the portions 34 of the sheets 20T and 20B from becoming wet. When the residue of the sheets 20T and 20B is wetted, the portions 34 that were prevented from wetting would be visually different. 4) Preferably, an opacifying material can be added to the laminating adhesive means 27, such that the modified laminating adhesive means becomes visually different when the paper towel sheets 20 are moistened with a substantially aqueous liquid. transparent.

In the preferred embodiment of the laminated paper towel 20, shown in Figures 1 and 2, an opacifying agent has been added to the laminating adhesive means 27 in order to provide the indicator means 29. The opacifying agent may comprise, any material which is commonly used in the art, such as pigments and the like. However, it should be recognized that when dry those portions 34 of the surfaces of the outer cover 30 and 32, which have been provided with a display means 29, should not be visually distinguished from those portions 36 of the surfaces of the outer cover. 30 and 32, which have not been provided with an indicator means 29. Preferably an opacifying agent suitable for the present invention has a refractive index of at least about 1.55. A suitable material, if the indicator means 29 is to comprise a modified lamination adhesive means 27, is 7% titanium dioxide pigment suspension in water, known as KRONOS 1050, and which is marketed by KRONOS Canada, Inc. de Varennes, Quebec. Also suitable are other white, inorganic pigments, such as zinc oxide, calcium carbonate, kaolin, and the like. Alternatively, an organic pigmentation medium, such as the Ropaque HP91 from Rohm & Haas Corp., Philadelphia, PA, to replace part or all of the titanium dioxide, or other inorganic pigment. The applicants have discovered that the composition below provides both satisfactory strength in the bonding of the layer in its paper of adhesive laminating medium, and a satisfactory moisture difference in the grayscale of the fibers that are found. around in its role as indicator means: Titanium Dioxide (KRONOS 1050): 15 parts Hydrolyzed Polyvinyl Alcohol Resin (Evanol 71 -30) 5 parts Water 80 parts 100 parts The steps detailed below can be used to prepare this lamination adhesive means 27: Polyvinyl Alcohol Resin Concentrate 1) Measure approximately 50 parts of water inside a container at room temperature. 2) Slowly add 8 parts of the hydrolyzed polyvinyl alcohol resin and mix to ensure that the resin has dispersed evenly. 3) Add the remaining 42 parts of water at room temperature, to the dispersion of the resin. 4) Heat the dispersion of the resin to a temperature of 185 ° F and mix for at least 45 minutes. 5) Allow the resin solution to cool to room temperature.

Preparation of the Modified Lamination Adhesive Medium 1) Measure 62.5 parts of the polyvinyl alcohol concentrate in a container. 2) Add and mix 15 parts of a 75% titanium dioxide paste. 3) Continue mixing and adding 22.5 parts of water at room temperature, using a part of the water, to rinse the container that was used for the titanium dioxide paste. 4) Continue mixing until a homogeneous mixture is obtained.

This modified lamination means 27 can be used later in the production of the laminated paper towel 20, as described below. Although the method described above provides a preferred composition of the modified laminating adhesive means 27, applicants have discovered that the laminating adhesive means 27, which comprise at least about 7 percent titanium dioxide solids , preferably, between about 7 percent solids of titanium dioxide and about 12 percent solids of titanium dioxide, provide an indicator means, which has a satisfactory difference in the wet gray scale.

To produce a laminated paper towel 20, of the preferred embodiment of the present invention, the series etching process of US Pat. No. 5 may be used., 294,475, referred to above. Preferred cellulosic fiber coils for substrate 20T and 20B are described in U.S. Patent No. 4,637,859, lamination adhesive means 27 and indicator means 29, described above. The resulting laminated paper towel 20 when dry has a nice cushioned appearance. Alternatively, the indicator means 29 can be applied to at least one of the sheets 20T or 20B, in a separate step of the process, such as printing the indicator means 29 on one or more of the sheets. This alternative process also has the advantage that it allows the indicator means 29 to be in a spatial relationship with respect to the separate engraved areas 22. Figures 3 and 4 are photographs, which show the preferred embodiment of the present invention , the rolled paper towel 20, both in its dry condition (Figure 3), and in its wet condition (Figure 4). Figure 3 clearly illustrates the padded appearance of the dry rolled paper towel. Users have indicated that this appearance implies both resistance and softness. It should also be noted that the indicator means 29 can not be seen when the laminated paper towel 20 is in its dry condition. When the laminated paper towel 20 is wet, as shown in Figure 4, the indicator means 29 becomes clearly perceptible. For comparison purposes, Figure 5 shows, in its dry condition, a laminated and engraved paper towel 20, which is similar in appearance to the towel shown in Figure 3 when it is dry, the towel shown in Figure 5 does not it has a display means 29. The difference in appearance between Figures 4 and 5 is evident. Consumers have indicated that this visible signal further provides confidence that the laminated paper towel 20 retains its desirable strength, softness and absorbency when wet (See Table 3 below). The difference in gray scale can also be used to show how the indicator means 29 becomes evident when the laminated paper towel 20 of the present invention is wetted with a substantially transparent aqueous liquid. The term "difference in gray scale", as used in the present description, refers to the difference in the level of gray scale, is measured using image analysis techniques, between portions 34 and 35 of a disposable paper product, for example, between the indicator means 29 and the unrecorded regions of the sheet 24 of the disposable paper product 20. The difference in the gray scale can be measured when the product of interest is either in its wet condition or in its dry condition. The following describes a suitable method to measure the difference in the gray scale. Table 1 shows the gray scale difference data for a modified lamination adhesive means 27, which also comprises different levels of titanium dioxide, a preferred opacifying agent for the indicator means 29.

Table 1 Solids Difference in the Opacifier Level Gray Scale Qpacifiers * (Gray Scale Units) None 0 0 Titanium dioxide 3.75 34 Titanium dioxide 7.5 64 Titanium dioxide 11 .25 75 * Difference in the level of gray scale, between the regions that contain indicator means 29, and the regions without recording 24, when the paper towel! laminate 20 of the present invention has been moistened with a substantially transparent aqueous liquid.

As clearly shown in Table 1, the increase in the amount of opacifier causes a corresponding increase in the difference in the gray scale, between the indicator means 29 and the sheets 20T or 20B. This is the difference that the visual signal provides to a user, which indicates that the laminated paper towel 20 retains its desirable properties even after it has been moistened with a substantially transparent liquid. Applicants have discovered that a gray scale moisture difference of at least 64 gray scale units, preferably of at least 67 gray scale units, and more preferably at least 70 gray units, is necessary. the gray scale, so that the indicator means 29, serves as a reliable visual signal, that the desirable properties of the laminated paper towel 20 of the present invention are preserved, when the product is moistened with a substantially transparent aqueous liquid. However, the gray scale difference, by itself, is not sufficient to provide a visual signal that clearly indicates that the full range of desirable properties of a disposable paper product are retained when it is moistened with a liquid watery substantially transparent. Applicants have also discovered that the indicator means 29, should be applied in a pattern that involves the preservation of said desirable properties when the disposable paper product is moistened with a substantially transparent aqueous liquid. The example that follows will serve to illustrate this point. As can be seen in Table 2, WALK'N ROLLtMf has a difference in grayscale much larger, than the other rolled paper towels of the current art that were tested and are available in the market. The towels WALK'N ROLLtM? they comprise a laminate of two sheets with a mesh between them.

Table 2 Products of the Difference in the Current Art Gray Scale (Units in the Gray Scale) WALK'N ROLL ™ 1 65 SCOTTOWELS®2 - 1 Towel BRAWNY®3 - 2 Towel BOUNTY®4 - 6 Kimberley Clark Corp., Dallas, TX Scott Paper Co., Philadelphia, PA 3 James River Corp., Norwalk, CT 4 Procter & Gamble Co., Cincinnati, OH The test carried out by the applicants with consumers has shown that the visual signal provided during wetting with a substantially transparent aqueous liquid, in a pattern comprising only interconnected elements in a continuous manner, does not indicate to users, a mixture balanced of the desirable properties. Those skilled in the art will recognize that the pattern of a mesh, as used in the WALK'N ROLL ™ product, consists of continuous elements, not separate elements. The terms "continuous elements" or "continuously interconnected elements" are intended to describe those elements of a pattern, which becomes evident when a disposable paper product is moistened with a substantially transparent aqueous liquid that extends in a manner uninterrupted The term "separate elements" is intended to describe those elements of a pattern, which become apparent when a disposable paper product is moistened with a substantially transparent aqueous liquid, which have interruptions between them, of the individual elements that they form a pattern when they are placed in combination.

Table 3 Different Panel Percentage Indicating That Statistically Product Key: Pattern is more than the Preferred Pattern Media Key for its Indicated Product Appearance Indication (90% Confidence) A: Separate Elements (Shown in Figure 4) 53 BCDEF 6; Diagonal Continuous Mesh * 18 DEF C: Interlock Double Sinusoidal Wave * 1 1 FD: Interlocking Circuits * 8 E: Square Continuous Mesh * 6 F: Without Means of Measurement (Shown in Figure 5) 4 * Indicator means 29 comprises a pattern of continuous elements Table 3, indicates the results of a sample test with the consumer, where a group of eighty-five consumers were asked the following: 1) observe a series of laminated paper towels 20, where > each towel of the series, has a display means 29 placed in one of the patterns described in Table 3, the towels being moistened with water, 2) placing the test towels in order of preference according to their appearance, and 3) relating the Test towels, based solely on their visual appearance, according to a series of properties such as strength, absorbency, softness, etc.

As shown more clearly in Table 3, the pattern of separate elements is most preferred over any of the continuously interconnected patterns that were tested. The evaluation of the determinations of the properties of the different patterns indicates that the consumers observed a better balance between the desirable properties that were conserved, when the indicator means 29 is placed in a pattern of discontinuous elements. A similar test also indicated that patterns visible during wetting with a substantially transparent aqueous liquid, which comprise combinations of separate elements and continuous elements, also imply for consumers, the preservation of a desirable balance of strength and softness.

Method of Testing the Difference in the Grayscale Basic Preparation of the Sample: The samples were prepared for the analysis, as indicated below. 1) Cut the sample 120 to be tested, in strips that are 2 inches long and 1 inch wide. 2) Use small clips (# BC-02, 0.375-inch capacity, Charles Leonard, Inc., Glendale, NY 11385), to adhere the strips of the individual samples, with the top of the surface of the sample, exposed crosswise on a sample holder (inclined aluminum rod 0.31 inches in diameter, U-shaped with a radius of curvature of approximately 0.69 inches).

Preparation of the Graphic Image Analysis System v of the Preparation Graphical System: It has been found that the graphic image analysis system 100, shown in Figure 6, is suitable for making the measurements of the difference in the level of the scale of grays The image analysis system 100 should be prepared as described in the present description in order to ensure that the data representative of the difference in the gray scale can be collected: 1) Camera 1 10: Panasonic Video Camera, Black and White (Model WV - BD400) 2) Lenses 1 12: Tamron SP 35 - 80 mm zoom lenses) Filter 1 14: Neutral Density Wratten 0.9 gelatine filter (Kodak Cat 149 6397)) Preparation of the lenses: The top f of the lenses must be placed in f-1 1 ...) Preparation of the Image Analysis System: Adhere the camera and lenses to the support for copies 120 (Polaroid MP-4). Place the sample strips 122, and the sample holder 124 over the top of a bottom table of sample 126 (0.125 inch black ink PVC-Queen City Polymers, West Chester, OH). Place the bottom table of sample 126, on top of a rectangular platform 128 (25 inches long x 8 inches deep x 3 inches tall). The distance h from the surface of the sample, up to the lens cover, it should be approximately 17 inches, if the sample holder and camera are positioned correctly. The strips of the samples and the fastener are illuminated from left to right, with the projecting lamps 130 (150 W), which shine on the sample at an angle of approximately 50 degrees in relation to the vertical. ) Calibration: The system should be checked and maintained every hour using a 14-inch Kodak Grayscale (Eastman Kodak Co, Rochester, NY). Specifically, the average gray level value from an area in the choke of the density stage of 1.0 of the Kodak Grayscale should be adjusted to the value of 41 of the grayscale, and it will not be allowed that vary more than ± 2 of the gray scale values. The average gray level value from an area in the colza of the 0.3 density stage of the Kodak Grayscale should be adjusted to the value of 153 of the gray scale, and it will not be allowed to vary more than ± 2 of the values of the gray scale. If necessary, the brightness and contrast of the intensity table of the structure can be adjusted to restore the calibration. The area of the background for the measurement of the average level of the gray scale should be at least 6 mm2. 5) Digitization and Image Capture: To digitize the images of the sample, you can use A table of intensity of the structure (MVP-AT - Matrox Electronic Systems LTD, Dorval, Quebec H9P 2T4, Canada), installed on a computer desktop staff (Compaq 386 / 33L with Windows Version 3.1). The images of the individual sample must be stored in the computer file for analysis. 6) Image Analysis Software: The average gray level values of any desired portion of a sample image can be measured using the Optimum Image Analysis Software Version 4.02 (Bioscan, Incorporated, Edmunds WA 98020). The final magnification of the image was approximately 6X Capture and Image Digitization: The following describes a suitable method to obtain and analyze the images of the disposable paper product samples, both in their dry condition and in their wet condition: 1) Obtain an image of the sample strip in its dry condition, using the image analysis apparatus, and preparing it as described above. 2) Moisten the sample, applying with a syringe of 1 ml, 0.35 ml of distilled water, up to half that of the upper surface (Hamilton Co, Reno, NV Gastight # 1001). 3) Obtain an image of the moistened sample after allowing the sample to calibrate for 1 1/2 minutes. 4) Then the level of the gray scale can be determined in selected portions of the sample, using the image analysis software.

Determination of the Difference in the Grayscale: The difference in the Grayscale is determined as described below: 1) The grayscale levels of the unrecorded region 24, (or other part of the sample, which the sheet has not been modified), and the gray scale level of the multiple recorded areas 22, the which have a modified lamination adhesive means 27 applied thereto, (or other zones comprising the indicator means 29), are determined and recorded for each of the samples, as described above. The gray scale level of five areas recorded on each of the four samples must be measured by obtaining a total of twenty data points, for each of the products of interest. ) For samples where the zones or other areas of interest are not substantially different at the gray scale level than the unrecorded areas, in order that the digitized image be clearly visible, a Preliminary image that accentuates the differences in the gray scale level, to identify the areas of interest before the actual measurements at the gray scale level are made. For the preliminary image, a 0.125-inch-thick piece of black PVC board is held in front of each of the lighting lights (Illumination from one side accentuates the engraving pattern). Using the optimum image analysis software, a point (approximately 0.1 mm2) can be placed over each of the recorded areas of interest, and a background area devoid of an engraving pattern can also be signaled. These locations are now identified for subsequent images of the sample strip. To ensure the alignment of the image, a registration mark was placed on the strip that was visible in the preliminary image, the image of the dry strip, and in the image of the strip once it has been moistened. ) The measurement was obtained, calculating the difference in the gray scale, subtracting the gray scale level of the unregistered screed 24, (or another portion of the sample, in which the sheet has not been modified), the grayscale level of each stamped area 22 (or other portion of the sample that could be comprised of the indicator means 29). The individual differences in the gray scale of each of the data points of the product of interest are calculated in this way, and are subsequently reported as the average value of the twenty data points. 4) The difference in gray scale can be determined for dry or wet samples.

Although the particular embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art, that other changes and modifications may be made, without departing from the spirit and scope of the present invention.

Claims (10)

1. R E I V I N D I C A I N N 1. A disposable paper product, which comprises: at least one sheet of paper with a relatively low basis weight; and a display means, placed in a portion of said at least one sheet, to provide a visual signal, which indicates that the properties of said paper with a relatively low basis weight are retained, when said paper with a basis weight relatively low is moistened with a substantially transparent aqueous liquid, wherein; said indicator means, comprises a pattern of separate elements; and said indicator means, can not be distinguished substantially visually, when said disposable paper product is dry, and said indicator means becomes visually distinguishable when the toilet paper product is moistened with a substantially transparent aqueous liquid.
2. 2. A disposable paper product, as described in Claim 1, further characterized in that the difference in gray scale, when said paper product is wetted with said aqueous liquid, between said portion of said at least one sheet , which is not provided with said indicator means, and said portion of said at least one sheet, which is provided with said indicator means, is at least about 64 units in the gray scale.
3. 3. A disposable paper product, as described in Claim 1, further characterized in that said paper product comprises a laminate of at least two sheets of said paper with a relatively low basis weight, which is bound by a medium laminating adhesive, wherein said laminating adhesive means also comprises an opacifying agent, said opacifying agent causing said laminating adhesive means to act as said indicating means.
4. 4. A disposable paper product, as described in Claim 1, further characterized in that said indicating means is generally placed between two of said sheets.
5. 5. A disposable paper product, as described in Claim 1, further characterized in that said indicating means comprises an ink.
6. 6. A disposable paper product, as described in Claim 1, further characterized in that said at least one sheet, additionally comprises at least two regions having different fiber compositions, said fiber compositions comprising a mixture of different types of fiber, wherein said fiber composition of at least one of the regions comprises at least one type of fiber, which has a refractive index which is substantially different from the types of fibers which comprises a remainder of said regions when said product is moistened with said fiber. aqueous liquid, providing said difference in the refractive index, said indicator means.
7. 7. A disposable paper product, as described in Claim 1, further characterized in that said at least one sheet, additionally comprises at least two regions, wherein one of said regions does not absorb considerable quantities of said aqueous liquids, said region providing not absorbing considerable quantities of said aqueous liquids. said indicator means. A disposable paper product, as described in Claim 3, further characterized in that said sheets comprise a first and a second sheet, said sheets being provided with engraved regions which comprise engravings having relatively distant ends, wherein said sheets Rolling adhesive means is applied to said relatively distant ends of at least a portion of said engravings. 9. A disposable paper product, as described in Claim 1, further characterized in that said pattern additionally comprises elements in a continuous form. 10. A disposable paper product, as described in Claim 9, further characterized in that the difference in grayscale when said disposable toilet paper product is wetted with an aqueous liquid between said portion of said at least one sheet, which is not provided with said indicator means, and said portion of said at least one sheet, which is provided with said indicator means, is at least about 64 units in the gray scale. 1. A disposable paper product, as described in Claim 9, further characterized in that said disposable paper product comprises a laminate of at least two sheets of said paper with a basis weight under which it is attached by a lamination adhesive means wherein said lamination adhesive means also comprises an opacifying agent, said opacifying agent causing said adhesive lamination means to act as said indicator means. 12. A disposable paper product, as described in Claim 9, further characterized in that said indicating means is generally placed between two of said sheets. 13. A disposable paper product, as described in Claim 9, further characterized in that said indicating means comprises an ink. A disposable paper product, as described in Claim 9, further characterized in that said at least one sheet further comprises at least two regions having different fiber compositions comprising said fiber compositions a mixture of different types of fibers wherein said fiber composition of at least one of the regions, comprises at least one type of fiber which has a refractive index which is substantially different to the types of fibers which comprise the rest of said regions when said product is moistened with said acuse liquid, said difference in the refractive index, said indicating means. 15. A disposable paper product, as described in Claim 9, further characterized in that said at least one sheet further comprises at least two regions wherein one of said regions does not absorb significant amounts of said aqueous liquid providing said region which does not absorb significant quantities of said aqueous liquids said indicator means. 16. A disposable paper product for use as paper towels, sanitary toilet paper and the like, said disposable paper product comprising: a first and a second sheet of paper with a relatively low basis weight, said sheets being provided with engraved regions being said engraved regions provided with engravings having relatively distant ends and with unrecorded regions; a laminating adhesive means, applied to at least a portion of said relatively distant ends of said engravings of said first sheet being thereby joined said relatively distant ends of said first sheet to said non-engraved regions of said second sheet; and an indicator means, placed in at least one of said sheets to provide a visual signal indicating that the desirable properties of said paper are conserved completely with a relatively low basis weight when said paper is moistened with a substantially transparent aqueous liquid. wherein said indicator means can not be visually distinguished when said disposable paper product is dry and said indicator means becomes distinguishable when said disposable paper product is moistened with a substantially transparent aqueous liquid wherein said indicator means is indistinguishable from Visual way when said disposable paper product is dry and said indicator means becomes visually distinguishable when said disposable paper product is moistened with a substantially transparent aqueous liquid said indicator means comprising a pattern of separate elements. 17. A disposable paper product, as described in Claim 16, further characterized in that the difference in level in the gray scale when said disposable paper product is wetted with said aqueous liquid between said paper with a basis weight relatively low and said indicating means is at least about 64 units in the gray scale. 1
8. 8. A disposable paper product, as described in Claim 16, further characterized in that said laminating adhesive means additionally comprises an opacifying agent originating said opacifying agent that said laminating adhesive means act as indicator means. 1
9. 9. A disposable paper product, as described in Claim 18, further characterized in that said opacifying agent has a refractive index greater than about 1.55 20. A disposable paper product, as described in Claim 18, further characterized in that the level of said opacifying agent in said rolling adhesive means it is at least 7 percent when said rolling adhesive means is prepared to apply it to said relatively distant ends of said engravings of said first sheet. 21. A disposable paper product, as described in Claim 18, further characterized in that said opacifying agent is selected from the group consisting of organic and inorganic pigmentation materials. 22. A disposable paper product, as described in Claim 17, further characterized in that at least a portion of said indicator means is placed in separate relation to said lamination adhesive means. 23. A disposable paper product, as described in Claim 22, further characterized in that said indicating means comprises an ink. EXCERPT OF THE INVENTION Paper products, such as paper towels, are provided with a display means, which is placed on said disposable paper product with a discontinuous pattern or a discontinuous / continuous combination. The indicating means provides a signal that is visually recognized to a user who wishes the properties of the disposable paper product to be retained, even after the disposable paper product has been moistened with a substantially transparent aqueous liquid. The gray scale of humidity, which marks the difference of the disposable paper product of the present invention, is at least about 64 gray scale units, when the disposable paper product is moistened with a substantially transparent aqueous liquid.