MXPA00001835A - Paper structures having different basis weights and densities - Google Patents

Paper structures having different basis weights and densities

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Publication number
MXPA00001835A
MXPA00001835A MXPA/A/2000/001835A MXPA00001835A MXPA00001835A MX PA00001835 A MXPA00001835 A MX PA00001835A MX PA00001835 A MXPA00001835 A MX PA00001835A MX PA00001835 A MXPA00001835 A MX PA00001835A
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MX
Mexico
Prior art keywords
regions
basis weight
paper web
weft
pattern
Prior art date
Application number
MXPA/A/2000/001835A
Other languages
Spanish (es)
Inventor
Paul Dennis Trokhan
Dean Van Phan
Original Assignee
The Procter & Gamble Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Procter & Gamble Company filed Critical The Procter & Gamble Company
Publication of MXPA00001835A publication Critical patent/MXPA00001835A/en

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Abstract

A non-through air dried paper web and method of making such a paper web are disclosed. The paper web includes at least two regions of different density and at least two regions of different basis weight. In one embodiment, the paper web includes a relatively high basis weight continuous network region, a plurality of discrete, relatively low basis weight regions dispersed throughout the relatively high basis weight continuous network region, and a plurality of discrete, intermediate basis weight regions circumscribed by the relatively low basis weight regions.

Description

PAPER STRUCTURES THAT HAVE DIFFERENT BASE PESOS AND DENSITIES CROSS REFERENCE OF THE RELATED APPLICATIONS This patent application claims the priority of the following United States Patent Applications, assigned jointly: United States Patent Application "Method and Apparatus for making Cellulosic Fibrous Structures by Selectively Obturated Drainage and Cellulosic Fibrous Structures Produced Thereby, filed on April 3, 1995 in the name of Trokhan et al., Which is a continuation of serial number 08 / 066,828 filed on May 24, 1993, which is a continuation of the number of Series 07 / 722,792 filed June 28, 1991; U.S. Patent Application Serial No. 08 / 710,822"Cellulosic Fibrous Structures Having at Least Three Regions Distinguished by Intensive Properties, Apparatus for and a Method of Making Such Cellulosic Fibrous Structures, filed on September 23, 1996 in the name of Phan et al., Which is a continuation of the Serial Number 08 / 613,797 filed on March 1, 1996, which is a continuation of Serial No. 08 / 382,551 filed on February 2, 1995 which is a two-dimensional serial number of 07 / 071,834 filed July 28, 1993, which is a continuation of the number of Series 07 / 724,551 filed on June 18, 1991; U.S. Patent Application Serial No. 08 / 802,094 filed February 19, 1997 in the name of Trokhan et al.; which is a continuation of serial number 08 / 601,910 filed on February 15, 1996, which is a continuation of serial number 08 / 163,498 filed on December 6, 1993, which is a continuation of the number of Series 07 / 922,436 filed on July 29, 1992; U.S. Patent Application Serial No. 08 / 748,871"Paper Web Hosting a Relatively Thinner Continuous Network Region and Discretely Relatively Thicker Regions in the Plan of the Continuous Network Region", filed on November 14, 1996 in the name of Phan; and U.S. Patent Application Serial No. 08 / 803,695"Paper Structures Having At Least Three Regions Including Decorative Indicia Comprising Low Basis Weight Regions, filed on February 21, 1997 in the name of Phan et al. as reference of U.S. Patents Nos. 5,534,426 issued July 9, 1996 to Trokhan et al., U.S. Patent No. 5,245,025 issued September 14, 1993 to Trokhan et al., Patent of the States. No. 5,277,761 issued January 11, 1994 to Phan et al .; and United States Patent No. 5,654,076 issued to Trokhan et al. On August 5, 1997. This patent application incorporates the following patent applications as a reference. : U.S. Patent Application No. 08 / 748,871"Paper Web Having a Relatively Thinner Continuous Network Region and Discreetly Relatively Thicker Regions in the Plan of the Continuous Network Region," prese November 14, 1996, on behalf of Phan; U.S. Patent Application No. 08 / 803,695"Paper Structures Having At Least Three Regions Including Decorative Indicia Comprising Low Basis Weight Regions, filed on February 21, 1997 in the name of Phan et al.
FIELD OF THE INVENTION The present invention relates to cellulosic fibrous structures having different base weights and densities, and more particularly, to non-through-air drying paper having different base weights and densities.
P1001 BACKGROUND OF THE INVENTION Cellulosic fibrous structures, such as paper, are well known in the art. It is often desirable to have regions of different base weights within the same cellulosic fibrous product. The two regions serve different purposes. The regions of higher basis weight impart tensile strength to the fibrous structure. Regions of lower basis weight can be used to economize raw materials, particularly, the fibers used in the papermaking process and to impart absorbency to the fibrous structure. In a degenerate case, the low basis weight regions may represent openings or holes in the fibrous structure. However, it is not necessary for low base weight regions to be open or perforated. The properties of absorbency and strength and, additionally, the property of softness, become important when the fibrous structure is used for the intended purpose. Particularly, the fibrous structure described herein can be used for disposable tissues, toilet paper, paper towels, bibs and napkins, each of which is currently in frequent use. If these products will perform their intended tasks and find wide acceptance, the fibrous structure must exhibit and increase P1001 to the maximum the aforementioned physical properties. The wet and dry tensile strengths are measures of the ability of a fibrous structure to retain its physical integrity during use. Absorbency is the property of the fibrous structure that allows it to retain the fluids with which it came into contact. Both the absolute amount of fluid and the speed at which the fibrous structure will absorb said fluid must be taken into consideration when evaluating one of the aforementioned consumer products. In addition, these paper products have been used in disposable absorbent articles, such as sanitary napkins and diapers. Attempts have been made in the art to provide paper having two different base weights or to rearrange the fibers in some other way. Examples include U.S. Patent No. 795,719 issued July 25, 1905 to Motz; U.S. Patent No. 3,025,585 issued March 20, 1962 to Griswold; U.S. Patent No. 3,034,180 issued May 15, 1962 to Greiner et al. U.S. Patent No. 3,159,530 issued December 1, 1964 to Heller et al .; U.S. Patent No. 3,549,742 issued December 22, 1970 to Benz; and United States Patent No. 3,322,617 issued May 30, 1967 to Osborne.
P01. Separately, there is a desire to provide tissue paper products that have both bulk and flexibility, such as through-air drying (TAD). Improved bulk and flexibility can be provided by means of bilaterally alternate compressed and non-compressed zones, as shown in U.S. Patent No. 4,191,609 issued March 4, 1980 to Trokhan, same patent incorporated herein. as reference. Several attempts are known to provide an improved foraminate member to manufacture these cellulose fibrous structures, one of the most significant being illustrated in U.S. Patent No. 4,514,345 issued April 30, 1985 to Johnson et al., Patent which is incorporated herein by reference. incorporated herein by reference. Johnson et al. teach hexagonal elements, attached to the frame in a batch liquid coating process. Another approach to the manufacture of tissue paper products with more preference by consumers is to dry the paper structure to impart to the tissue paper products greater bulk, tensile strength and burst resistance. Examples of paper structures manufactured in this manner are those illustrated in United States Patent No. 4,637,859 issued on January 20, P1001 1987 to Trokhan, patent incorporated herein by reference. U.S. Patent No. 4,637,859 shows discrete dome-shaped protrusions dispersed with an entire continuous network and is incorporated herein by reference. The continuous network can provide strength, while relatively thicker domes can provide softness and absorbency. A disadvantage of the continuous web disclosed in U.S. Patent No. 4,637,859, is that the drying of said web can be expensive and with relatively intensive energy use and usually includes the use of air drying equipment. intern In addition, the papermaking method disclosed in U.S. Patent No. 4,637,859 may be limited with respect to the speed at which the web may finally be dried in the Yankee dryer drum. It is believed that this limitation is due, at least partially, to the pattern imparted to the continuous web or frame before the transfer of the frame to the Yankee drum. In particular, discrete domes, described in U.S. Patent No. 4,637,859 may not be dried on the surface of the Yankee as efficiently as the continuous network described in U.S. Patent No. 4,673,859. In accordance with the above, for a level of P1001 determined consistency and basis weight, the speed at which the Yankee drum can be operated is limited. Conventional tissue paper manufactured by pressing a continuous web or web with one or more press felts in a gripper press can be manufactured at relatively high speeds. The conventionally pressed paper, once dry, can be embossed or engraved then with the pattern of the weft and to increase the macrocalibre of the weft. For example, embossed or embossed patterns formed in tissue paper products are common after the tissue paper products have dried. However, the engraving or embossing processes normally impart a particular aesthetic appearance to the paper structure at the expense of other properties of the structure. In particular, the etching of a dry paper web breaks or interrupts the links between the fibers of the cellulosic structure. This interruption or rupture occurs because the bonds or unions are formed and fixed with the drying of the embryonic fibrous pulp. After drying of the paper structure, the movement of the fibers normal to the plane of the paper structure by engraving breaks the bonds or bonds of fiber with fiber. The breaking of the joints results in a reduced tensile strength of the P1001 dry paper web. In addition, embossing is normally performed after creping the dry paper web from the drying drum. The embossing after creping can interrupt the creping pattern imparted to the weft. For example, etching can eliminate the creping pattern in some portions of the weft when compacting or stretching the creping pattern. This result is undesirable, because the creping pattern improves the softness and flexibility of the dry weft. In accordance with the above, an object of the present invention is to provide a paper and a method for manufacturing a multi-region or multiregional paper web, wherein the web has a predetermined pattern of regions of relatively low density and relatively high, yet It can be dried with a relatively lower cost and energy. Another object of the present invention is to provide a method for manufacturing a multi-region or multi-regional paper having at least and, preferably, at least three different base weights. Another object of the present invention is to provide a dried paper web with non-through air having different base weights and different densities. Another object of the present invention is to provide a paper web having a visually distinct pattern, provided by the combination and / or the interference of two different non-random repeat patterns.
SUMMARY OF THE INVENTION The present invention provides a dried paper web with non-through air comprising at least two regions of different density and at least two regions of different basis weight. The paper web may include an essentially continuous network region of relatively high density and a multitude of discrete regions of relatively low density, separated, dispersed throughout the continuous network region of relatively high density. The paper web can also comprise a relatively high basis weight, essentially, the continuous network region. The paper may further comprise a multitude of discrete regions with relatively low basis weight, scattered throughout the continuous network with relatively high basis weight and a multitude of discrete regions with intermediate basis weight, wherein the regions of intermediate basis weight generally they are circumscribed by the relatively low basis weight regions. In one embodiment of the present invention, the paper web has at least two regions of different PÍO01 basis weight, located in a first non-random repeat pattern and at least two regions of different density, located in a second non-random repeat pattern; where the first and second patterns are combined to provide a third visually distinguishable pattern, the third pattern is different from the first and second patterns. The present invention also provides a method for producing a non-through-air dried paper web having at least two regions of different basis weight and at least two regions of different density. The method includes the steps of: providing a multitude of fibers suspended in a liquid carrier or carrier; providing a forming element with fiber retention, having liquid permeable zones; depositing the fibers and the vehicle or liquid carrier on the forming element; draining the liquid carrier through the forming element in at least two simultaneous stages to form a web having at least two regions of different basis weight; providing a weft support apparatus comprising a surface for modeling or patterning the weft and a layer of dewatering felt; transferring the web from the former to the patterned surface for the web of the web support apparatus; selectively densifying a portion of the weft to provide the weft at least two different densities; and, dry the plot. The step of selectively densifying a portion of the frame comprises providing a continuous network region of relatively high density and a multitude of discrete regions of relatively low density dispersed throughout the continuous network region of relatively high density. The drain path of the liquid carrier through the forming element can include forming a web having a relatively high basis weight continuous network and a multitude of discrete relatively low basis weight regions dispersed throughout the continuous network of relatively high basis weight . In one embodiment, the step of draining the liquid vehicle through the forming element comprises forming a web having a relatively high continuous base web region; a multitude of discrete regions of relatively low basis weight, scattered throughout the relatively high basis weight continuous network region and a multitude of discrete regions of intermediate basis weight circumscribed by the relatively low basis weight regions.
BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with the claims that in a particular way indicate and P1001 claim distinctive to the present invention, it is considered that the invention is better understood from the following detailed description taken together with the associated drawings, in which similar elements are designated by the same reference number and: Figure 1 is a photograph of a paper web made in accordance with the present invention, wherein a portion of the paper web is placed on a black background and, where another portion of the paper web is placed on a white background. The scale in Figure 1 has divisions of 1/100 of an inch. Figure 2 is a schematic illustration of a paper web of the type shown in Figure 1. Figure 3 is a schematic cross-sectional illustration of a paper web of the type shown in Figure 2. Figure 4 is a schematic illustration of a paper machine that can be used to manufacture the paper web of the present invention. Figure 5 is a fragmentary top plan view of a forming element having discrete protuberances and openings or perforations extending through the protuberances. Figure 6 is a cross-sectional illustration of the forming element shown in FIG.
P1001 Figure 5. Figure 7 is an illustration of the fragmentary top plan view of a portion of the side of the sheet of a weft support apparatus. Figure 8 is a schematic cross-sectional illustration showing the paper web transferred to the weft support apparatus of the type shown in Figure 7, to provide a web of paper having a first surface conformed to the apparatus and a second surface practically smooth. Figure 9 is a schematic illustration showing a paper web that will be transferred from the weft support apparatus of Figure 7 to a Yankee dryer.
DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a photograph of a paper web 20 made in accordance with the present invention. Figure 2 is a schematic illustration of the image of Figure 1. Figure 3 is a cross-sectional illustration of a paper web 20 of the type shown in Figure 1. The paper web 20 was laid out or placed in humid and is practically free of dry engravings. The paper web 20, as shown in Figure 1, is a weft dried with non-through air. Through the term "dried P1001 with non-through air "is meant that the weft was not pre-dried in a dryer fabric by directing hot air through selected portions of the weft and the fabric or drying fabric." Referring to Figures 1-3, the paper web 20 has opposite first and second surfaces 22 and 24. The paper web 20 comprises at least two regions having different densities, located in a non-random repeat pattern.The paper web 20 also comprises at least two regions that have different base weights, located in a non-random repeat pattern The density of lines through the thickness of the frame, in Figure 3, is used to schematically illustrate the relative basis weights of different portions of the The portions of the weft, illustrated with 5 lines through the thickness of the weft represent regions of relatively high basis weight, the portions of the weft illustrated with 3 l Lines across the thickness of the weft represent regions of relatively low basis weight and the portions of the weft illustrated with 4 lines through the thickness of the weft represent regions of intermediate basis weight. In the embodiment shown in Figures 1 to 3, the paper web 20 is formed to have a network 40 P1001 essentially continuous and of relatively high basis weight and a plurality of discrete regions 60, separated and of relatively low basis weight, dispersed throughout the network 40. In Figure 1, the regions of different basis weight are visible in a portion of the weft on a black background. In the embodiment shown, the paper web 20 further comprises a multitude of discrete regions 80 of intermediate basis weight. Each region 80 of intermediate basis weight is generally circumscribed by a region of relatively low basis weight. Each intermediate base weight region 80 is coupled to a relatively low basis weight region 60 and is separated from the relatively high base weight continuous network 40 by its associated relatively low base weight region 60. The relatively low basis weight regions 60 may have the feature that the regions 60 comprise radially oriented fibers, which extend from the intermediate base weight regions 80 to the substantially continuous network of relatively high basis weight. Alternatively, region 60 may comprise fibers that are non-radially oriented. In another alternative embodiment, the paper web 20 does not have an intermediate base weight region 80 but instead has only regions of two base weights corresponding to two regions 40 and 60.
P1001 The paper web 20 of the present invention is selectively densified to provide at least two regions of different density. In the embodiment shown in Figures 1 to 3, the paper web 20 is selectively densified to provide an essentially continuous network region 110 of relatively high density and a multitude of discrete regions 130 of relatively low density, dispersed by the entire continuous network region 110. The regions 130 are relatively thicker, ie, thicker, than the region 110. In Figure 1, the network region 110 and the relatively low density regions 130 are visible in the portion of the frame placed on a white background. The number of relatively low basis weight regions 60 per unit area may be the same as or different from the number of regions 130 of relatively low density per unit area. For example, the number of relatively low basis weight regions 60 per unit area may be smaller or, alternatively, greater than the number of low density regions 130 per unit area. In the embodiments shown in Figures 1 and 2, the number of regions 60 per relatively low basis weight per unit area of the frame is greater than the number of regions 130 of relatively low density.
P1001 per unit area of the frame. The number of regions 60 per unit area can be at least 25 percent greater than the number of regions 130 per unit area. The paper web may comprise between about 10 and about 400 of the 60 per square inch regions and the paper web 20 may comprise between about 8 and about 250 of the 130 regions per square inch. In one embodiment, the paper web comprises between about 90 and about 110 of the 60 regions per square inch and between about 60 and about 80 of the 130 regions per square inch. In the embodiment shown in Figure 2, the shape defined by the perimeter of the regions 130 is generally the same as the shape defined by the perimeter of the regions 60. The regions 60 and 130 each have a perimeter that defines a shape that is elongated in the machine direction. Alternatively, regions 60 and 130 could have different shapes. The paper web 20 shown in Figures 1 and 2 has the feature that the regions of different basis weight are located in a first non-random repeat pattern and the regions of different density are located in a second repeat pattern.
P1001 not random. These first and second patterns combine to provide a visually distinguishable third pattern, which is different from the first and second patterns. The third pattern is visible in Figure 1 and indicated in dotted lines in Figure 2. The third pattern comprises a plurality of first flutes 210 and a plurality of second flutes 220. In Figures 1 and 2, the first flutes intersect with the second grooves 220 and the first and second grooves 210 and 220 extend diagonally with respect to the directions of the machine and in the transverse direction. The third pattern provides a plurality of diamond shaped cells 250. Without being limited by theory, it is considered that the third visually distinguishable pattern is provided by interference between density and base weight patterns. In particular, the third pattern is considered to be related to Moire or Moire-like interference of repetition patterns of density and basis weight. Without being limited by theory, it is believed that one or both of the first and second patterns can be varied to provide a different third pattern. For example, the size, shape or spacing of one or both of the regions 60 and 130 can be varied to provide a third P1001 different pattern. Alternatively, the relative orientation of the first and second patterns can be varied to provide a different third pattern. For example, the first pattern can be rotated with respect to the second pattern to provide a different third pattern. As shown in Figures 1 and 2, each cell 250 encloses several regions 60 and 80 of discrete basis weight. Each cell 250 also encloses several regions 130 of discrete density. The cells 250 of the third pattern have a repetition pattern much greater than the repetition pattern of the regions of different density and the repetition pattern of the different regions of different basis weight. According to the above, the paper webs according to the invention have the advantage that they provide a visually discernible large-scale pattern without the need to engrave or emboss and without the need to make large-scale changes in basis weight or density of the paper plot. The non-through air air dry paper web 20, made in accordance with the present invention, may have a smoothness value of less than about 1000 on at least one of the facing surfaces facing the opposite way. In Figure 3, the smoothness value of the surface 24 is less than the smoothness value of the surface 22. The smoothness value of the P1001 surface 24 is preferably less than about 1000. The smoothness value of surface 22 can be greater than about 1000. In particular, paper web 20 can have a surface smoothness ratio greater than about 1.10, wherein the proportion of surface smoothness is the value of the surface smoothness of the surface 22 divided by the value of the smoothness of the surface 24. In one embodiment, the surface 24 of the screen 20 may have a surface smoothness value of less than about 960 and the Opposite surface 22 may have a surface smoothness value of at least about 1150. The method for measuring the surface smoothness value of a surface is described below in the subtitle "surface smoothness". The surface smoothness value of a surface increases as the surface becomes more textured and less smooth. In accordance with the foregoing, a relatively low surface smoothness value indicates a relatively smooth surface. Base weights of regions 40, 60 and 80 can be measured using the method for measuring the basis weights of the regions of a paper web, as set forth in U.S. Patent No. 5,503,715 issued P1001 on April 2, 1996 to Trokhan et al., Patent incorporated herein by reference. The basis weight of the region 40 is preferably at least about 25 percent greater than the base weight of the region 80 and the basis weight of the region 80 is preferably at least about 25 percent greater than the base weight of the region. 60. The continuous network region 110 and the discrete regions 130 can both be reduced, such as, for example, by creping or wet microcontraction. In Figures 2, the creping edges of the continuous network region 110 are designated by the number 115 and extend generally in the transverse direction of the magneto. Similarly, discrete regions 130 of relatively greater thickness and of relatively smaller density can also be reduced to have creping edges 135. Creping flanges 115 and 135 are shown, for clarity, only in a portion of the paper web 20. of Figure 2. U.S. Patent No. 4,444,597 issued April 3, 1984 to Wells et al. it is incorporated herein by reference in order to reveal wet microcontraction. The continuous network region 110 may be a macroscopically monoplane continuous network region of relatively high density of the type disclosed in P1001 U.S. Patent No. 4,637,859, which is incorporated herein by reference. The regions 130 of relatively greater thickness and of relatively smaller density can alternate bilaterally, as disclosed in U.S. Patent No. 4,637,859. However, the regions 130 are preferably not domes of the type shown in U.S. Patent No. 4,637,859. The regions 130 are located in the plane of the continuous network region 110, as disclosed in United States Patent Application Serial Number 08 / 748,871"Paper Web Having A Relatively Thinner Continuous Network Region &Discrete Relatively Thicker Regions In the Plañe of the Continuous Network Region, filed on November 14, 1996 in the name of Phan, application which is incorporated herein by reference.The paper web 20 having the relatively smooth surface 24 may be useful for making a paper multi-sheet tissue having smooth, outwardly facing surfaces For example, two or more wefts 20 may be combined to form a multi-sheet tissue paper, such that the two outwardly facing surfaces of the multi-sheet tissue paper comprise the surfaces 24 of the wefts 20 and the surfaces 22 of the external leaves facing in. Alternatively, a two-sheet paper structure P1001 can be manufactured by joining a weft 20 of the present invention to a paper web formed and dried in a conventional manner. The weft 20 can be attached to the conventional paper web, such that the surface 24 faces outwards. The paper web 20 can have a sheet basis weight (macroscopic in comparison to the base weights of the individual regions 40, 60, 80) of about 10 to about 70 grams per square meter.
DESCRIPTION OF THE METHOD FOR THE MANUFACTURE OF PAPER A paper structure 20, in accordance with the present invention, can be manufactured with the apparatus for manufacturing paper, which is shown in Figures 4. The method for manufacturing the paper structure 20 of the present invention is initiated by providing a multitude of fibers suspended in a liquid carrier, such as an aqueous dispersion of paper fibers in the form of a pulp and by depositing pulp of paper fibers from a head tub 1500 on a forming element 1600 which retains fibers. The forming element 1600 is, in Figure 4, in the form of a continuous band. The pulp of paper fibers is deposited on the forming element 1600 and the pulp drains the water through the forming element 1600 to form a weft Embryonic P1001 of papermaking fibers 543 supported by forming member 1600. Pulp of papermaking fibers can include relatively long fibers having an average fiber length greater than or equal to 2.0 mm and relatively short fibers having a lower average fiber length of 2.0 mm. For example, the relatively long fibers may comprise softwood fibers and the relatively short fibers may comprise hardwood fibers. The fibers of hardwood and softwood are discussed in more detail below. Figures 5 and 6 show the forming element 1600. The forming element 1600 has two mutually opposite faces, a first face 1653 and a second face 1655. The first face 1653 is the surface of the forming element 1600 which makes contact with the fibers of the plot that will be formed. The first face 1653 has two distinct regions 1653a and 1653b. The forming element 1600 has flow restricting members in the form of protuberances 1659 which form the low basis weight regions 60. The protrusions 1659 are spaced apart to provide intermediate flow angles 1665. The intermediate flow portions 1665 form the high basis weight regions 40. The protrusions 1659 may each have, P1001 an opening 1663 extending through the protrusion 1659. The openings 1663 provide the regions 80 of intermediate basis weight. The forming element 1600 shown comprises a pattern array of protrusions 1659, attached to the reinforcing structure 1657, which may comprise a foraminous element, such as a woven screen or other perforated or apertured frame. The reinforcing structure 1657 is practically fluid permeable. The flow resistance of the opening 1663 is different from the flow resistance, and is usually greater, of the intermediate flow angles 1665 between adjacent protrusions 1659. Therefore, through the angles 1665 it will normally drain more of the liquid carrier than through the openings 1663. The intermediate flow angles 1665 and the openings 1663, respectively define high flow and low flow areas in the forming element 1600 The difference in the flows or flow regimes through the zones is referred to as "drainage or stepped drainage". The stepped drainage provided by the forming element 1600 can be used to deposit different amounts of fibers in preselected portions of the paper web 20. In particular, the high weight region 40 will be presented in a pattern of P1001 non-random repetition that corresponds to practically the areas of relatively high flow (the angles 1665). Intermediate basis weight regions 80 will be presented in a non-random repeat pattern that corresponds substantially to areas of relatively lower flow rate (openings 1663, and the relatively low basis weight regions 60 will be presented in a non-random repeat pattern that corresponds substantially to the zone of zero flow, provided by the protrusions 1659. Suitable constructions for the forming element 1600 are disclosed in the US Pat. No. 5,534,326 issued July 9, 1996 to Trokhan et al. , and in U.S. Patent No. 5,245,025 issued September 14, 1993, Patents which are incorporated herein by reference. The forming element 1600 can have between about 10 and about 400 protuberances per square inch. In one embodiment, the forming element may have between about 90 and 110 protrusions per square inch. In one embodiment, the forming element 1600 may have approximately 100 protrusions 1659 per square inch. The protuberances 1659 may have the shape shown in Figure 5 and may have a dimension A P1001 in MD (machine direction) of 0.105 inches, dimension B in CD (in machine direction) of approximately 0.074 inches, separation C in machine direction of 0.136 inches and spacing D in the cross direction to the 0.147 inch machine. The minimum separation E between adjacent protuberances can be 0.029 inches. The protrusions 1659 may have a height H less than about 0.010 inches. The openings 1663 may have an elliptical shape with a major axis parallel to the machine direction of approximately 0.052 inches and a minor axis of approximately 0.037 inches. The upper surface of the protuberances 1659 can provide approximately 35 percent of the projected area of the forming element 1600, as seen in Figure 5. The openings 1663 can provide approximately 15 percent of the projected area of the forming element 1600, as seen in FIG. Figure 5. The angles 1665 provide approximately 50 percent of the projected area of the forming element 1600, as seen in Figure 5. It is anticipated that wood pulp, in all its varieties, will normally comprise the paper fibers used in this. invention. However, other fibrous cellulose pulps, such as cotton linings, bagasse, P1001 rayon, etc., can be used and none are rejected. Wood pulps useful herein include chemical pulps, such as Kraft, sulphite and sulfate pulps as well as mechanical pulps, which includes, for example, ground wood, thermomechanical pulps and chemo thermo-chemical pulps (CTMP). Pulps derived from both deciduous and coniferous trees can be used. Alternatively, other non-cellulosic fibers, such as synthetic fibers, may be used. Both hardwood pulp and soft wood pulp can be used, either separately or together. The hardwood and softwood fibers can be mixed, and / or alternatively, they can be deposited in layers to provide a stratified web. U.S. Patent No. 4,300,981 issued November 17, 1981 to Carstens and U.S. Patent No. 3,944,771 issued November 30, 1976 to Morgan et al. they are incorporated herein by reference in order to reveal the staging of hard and soft wood fibers. The stock can comprise a variety of additives including, but not limited to, fiber binder materials, such as binder materials for wet strength, binder materials for dry strength and softening compositions.
Chemical P1001 Suitable binders for wet strength include, but are not limited to, materials such as polyamide-epichlorohydrin resins that are sold under the tradename KYMENE® 557H from Hercules Inc., Wilmington, Delaware. Suitable binders for temporary wet strength include, but are not limited to, synthetic polyacrylates. A suitable binder for temporary wet strength is the PAREZ® 750 marketed by American Cyanamid of Stanford, CT. Suitable binders for dry strength include materials such as carboxymethylcellulose and cationic polymers, such as ACCO® 711. The CYPRO / ACCO family of materials for dry strength can be obtained from CYTEC of Kalamazoo, MI. The pulp deposited in the forming element 1600 may comprise an unraveling agent to inhibit the formation of some fiber or fiber bonds, as the weft dries. The unraveling agent, in combination with the energy provided to the web by the dry creping process, results in a portion of the web losing bulk. In one embodiment, the unraveling agent can be applied to the fibers that form an intermediate fiber layer, placed between two or more layers. The middle layer acts as an unraveling layer P1001 between outer layers of fibers. The creping energy can, therefore, remove volume from a portion of the weft along the unraveling layer. As a result, the weft can be formed to have a relatively smooth surface for sufficient drying on a heated dryer surface, such as the heated drying surface of a Yankee dryer drum. In, but, because the creping blade or sheet regains volume, the dry web may also have regions of differential density, including a continuous network region of relatively high density and discrete regions of relatively low density that are created by the crepad process. Suitable disintegrating agents include chemical softening compositions, such as those disclosed in U.S. Patent No. 5,279,767 issued January 18, 1994 to Phan et al. Compositions suitable for chemical softening, biodegradable, are disclosed in U.S. Patent No. 5,312,522 issued May 17, 1994 to Phan et al. U.S. Patent Nos. 5,279,767 and 5,312,522 are incorporated herein by reference. These chemical softening compositions can be used as disentangling agents to inhibit fiber-to-fiber bonding in one or more of the fiber layers that P1001 constitute the plot. A suitable softener for providing the unraveling of the fibers in one or more of the layers of fibers forming the layer 20, is an additive for papermaking, comprising Distebo Chloride Disebo (Touch-hardened) Dimethylammonium. A suitable softener is the ADOGEN® brand paper additive, which can be obtained from Witco Company of Greenwich, CT. The embryonic web 543 is preferably prepared from an aqueous dispersion of the paper fibers, although dispersions in other liquids than water can be used. The fibers are dispersed in the carrier liquid to have a consistency of from about 0.1 to about 0.3 percent. The percent of consistency of a dispersion, pulp, weft or other system is defined as 100 times the quotient obtained when the passage of the dry fiber of the system under consideration is divided by the total weight of the system. The weight of the fiber is always expressed based on totally dry fibers. The embryonic web 543 can be formed in a continuous papermaking process, as shown in Figure 4 or, alternatively, a batch process, such as a process for the manufacture of handmade sheets, can be used. Afterwards, the dispersion of PIOOI paper fibers are deposited on the forming element 1600, the embryonic web 543 is formed by removing a part of the aqueous dispersion medium through the forming element 1600, thanks to techniques well known to those skilled in the art. Vacuum boxes, forming boards, hydrofoils and the like are useful for effecting the removal of water from the aqueous dispersion of paper fibers to form the embryonic web 543. Referring again to Figure 6, the height H may be less than about 0.010 inches. in order to provide an embryonic web 543, generally monoplane, having substantially smooth first and second surfaces (the first surface and the second surface are designated 547 and 549 in Figure 8). The next step in the manufacture of the paper web 20 comprises transferring the embryonic web 543 of the forming element 1600 to the web support apparatus 2200 and supporting the transferred web (designated with the number 545 in Fig. 4) on the first side 2202 of the web. apparatus 2200. Preferably, the embryonic web has a consistency of between about 5 and about 20 percent at the point of transfer to the web support apparatus 2200. Referring to Figures 7 to 8, the weft support apparatus 2200 comprises a felt layer of P1001 dewatering 2220 and a modeling layer 2250 or to apply a pattern to the weft. The weft support apparatus 2200 may be in the form of a continuous web for drying and for imparting a pattern to the paper web in a paper machine. The frame support apparatus 2200 has a first side 2202 that faces the frame and a second side 2204 that faces the opposite direction. The frame support apparatus 2220 is seen, in Figure 7, with the first side 2202 facing the weft, towards the observer. The first side 2202 oriented towards the frame, comprises a first surface that makes contact with the frame. In Figures 7 and 8, the first surface contacting the web is a first felt surface 2230 of the felt layer 2220. The first felt surface 2230 is located at a first elevation 2231. The first felt surface 2230 It is a felt surface that makes contact with the weft. The felt layer 2220 also has a second felt surface 2232 oriented in the opposite direction. - The second surface that makes contact with the frame is provided by the modeling layer 2250 or to apply a pattern to the frame. The pattern modeling layer 2250, which is attached to the felt layer 2220, has a surface 2260 that contacts the weft at a second elevation.
P1001 The difference between the first elevation 2231 and the second elevation 2261 is less than the thickness of the paper web when the paper web is transferred to the web support apparatus 2200. The surfaces 2260 and 2230 can be located at the same elevation, so that the elevations 2231 and 2261 are equal. Alternatively, surface 2260 may be slightly above surface 2230 or, surface 2230 may be slightly above surface 2260. The difference in elevation is greater than or equal to 0.0 mils and less than approximately 8.0 mils. . In one embodiment, the difference in elevation is less than about 6.0 thousandths of an inch (0.15 mm), more preferably less than about 4.0 thousandths of an inch (0.10 mm) and most preferably less than about 2.0 thousandths of an inch (0.05 mm), in order to maintain a relatively smooth surface 24. The dewatering felt layer 2220 is permeable to water and has the ability to receive and contain the pressed water from a wet weft of paper fibers. The modeling layer 2250 or to pattern the weft is impermeable to water and does not receive or contain pressurized water from a web of paper fibers. The pattern modeling layer 2250 may have a continuous top surface 2260 P1001 making contact with the frame, as shown in Figures 8 and 9. Alternatively, the frame modeling layer may be discontinuous or semi-continuous. The pattern modeling layer 2250 preferably comprises a photosensitive resin which can be deposited on the first surface 2230, as a liquid and subsequently cured by radiation, so that a portion of the pattern modeling layer 2250 penetrates and thus joins or adheres securely to the first felt surface 2230. The weft pattern layer 2250 preferably does not extend through the entire thickness of the felt layer 2220 but, instead, extends through the approximately less than half the thickness of the felt layer 2220 to maintain the flexibility and compressibility of the weft support apparatus 2200 and, particularly, the flexibility and compressibility of the felt layer 2220. A felt layer 2220 of dewatering suitable comprises a non-woven wipe 2240 of bound natural or synthetic fibers, such as by basting, to a support structure formed of woven filaments 2240. Suitable materials from which non-woven tow can be formed include, but are not limited to, natural fibers, such as wool and synthetic fibers such as polyester and nylon. The P1001 fibers from which tow 2240 was formed, can have a denier of between about 3 and about 20 grams per 9000 meters of filament length. The felt layer 2220 may have a stratified construction and may comprise a mixture of fiber types and sizes. The felt layer 2220 is formed to promote transport of water received from the web away from the first felt surface 2230 and toward the second felt surface 2232. The felt layer 2220 may have finer fibers compacted or packed in relatively dense shape, located adjacent to the first felt surface 2230. The felt layer 2220 preferably has a relatively high density and a relatively small pore size adjacent the first felt surface 2230, as compared to the density and the pore size of the felt layer 2220 adjacent the second felt surface 2232, such that water entering the first surface 2230 is transported away from the first surface 2230. The felt layer 2220 dewatering it can have a thickness greater than about 2 mm. In one embodiment, the felt layer 2220 of dewatering can have a thickness of between about 2 mm and about P1001 5 mm. PCT publications, WO 96/00812 published January 11, 1996, WO 96/25555 published August 22, 1996; WO 96/25547 published August 22, 1996, all in the name of Trokhan et al; U.S. Patent Application 08 / 701,600"Method for Applying to Resin to Substrate for Use in Papermaking" filed on August 22, 1996; US Patent Application 08 / 640,452"High Absorbency / Low Reflectance Felts with a Pattern Layer" filed on April 30, 1996 and United States Patent Application 08 / 672,293"Method of Making Wet Pressed Tissue Paper with Felts Having Selected Permeabilities "filed June 28, 1996, are incorporated herein by reference in order to disclose the application of a photosensitive resin to a dewatering felt and in order to reveal suitable dewatering felts. The dewatering felt layer 2220 may have an air permeability of less than about 200 standard cubic feet per minute (scfm), where air permeability in scfm is a measure of the number of cubic feet of air per minute passing through from an area of one square foot of the felt layer, to a differential pressure across the thickness of the dewatering felt of approximately 0.5 inch of water. In a P1001 mode, the dewatering felt layer 2220 may have an air permeability of between about 5 and about 200 scfm and, more preferably, less than about 100 scfm. The dewatering felt layer 2220 can have a basis weight of between about 800 and about 2000 grams per square meter, an average density (basis weight divided by thickness) of between about 0.35 grams per cubic centimeter and about 0.45 grams per cubic centimeter . The air permeability of the weft support apparatus 2200 is less than or equal to the permeability of the felt layer 2220. A suitable felt layer 2220 is an Amflex 2 Press Felt, manufactured by the Appleton Mills Company of Appleton, Wisconsin. The felt layer 2220 can have a thickness of about 3 millimeters, a basis weight of about 1400 g / square meters, an air permeability of about 30 scfm, and has a double layer support structure having an upper part of 3 multifilament sheets and a lower screen and a warp in cross direction to the monofilament machine of 4-leaf cable. The tow 2240 may comprise polyester fibers having a denier of about 3 on the first surface 2230 and a denier of about 10-15 on the tow substrate P1001 underlying the first surface 2230. The frame support apparatus 220, which is shown in Figure 7, has a pattern modeling layer 2250 having a continuous network pattern that makes contact with the upper surface 2260 that in the The same has a multitude of discrete openings 2270. In Figure 7, the shape of the openings 2270 is substantially the same as the shape of the perimeter of the protuberances 1659, as seen in Figure 5. Suitable shapes for the openings 2270 include , enunciatively, circles, ovals, polygons, irregular forms or mixtures of these. The projected surface area of the continuous network top surface 2260 may be between about 5 and about 75 percent of the projected area of the weft support apparatus 2200, as seen in Figure 7, and preferably, it is between about 25 per cent. one hundred and about 50 percent of the projected area of the apparatus 2200. The continuous net upper surface 2260 may have between about 8 and about 350 discrete openings 2270 per square inch of the projected area of the apparatus 2200, as seen in Figure 7. In In one embodiment, the upper surface 2260 of continuous network can have approximately 60 a P1001 approximately 80 discrete openings 2270 per square inch. The discrete apertures 2270 may be bilaterally alternated in machine direction (MD) and machine direction (CD), as described in U.S. Patent 4,637,859 issued January 20, 1987, which is incorporated herein by reference. the present as a reference. Alternatively, other photopolymer standards may be used to provide different models or densification patterns of the screen. The frame is transferred to the frame support apparatus 2200, such that the first face 547 of the transferred frame 545 is supported and conformed to the side 2202 of the apparatus 2200, where the portions of the frame 545 are supported on the surface 2260 and the parts of the weft are supported on the felt surface 2230. The second face 549 of the weft is maintained in a macroscopically monoplane configuration, practically smooth. Referring to Figure 8, the difference in elevation between the surface 2260 and the surface 2230 of the weft support apparatus 2200 is sufficiently small, so that the second face of the weft remains virtually smooth and macroscopically monoplane when the weft is transferred to the weft. apparatus 2200. In particular, the elevation difference 2261 of surface 2260 and the P1001 elevation 2231 of surface 2230 should be smaller than the thickness of the embryonic web at the point of transfer. The steps for transferring the embryonic web 543 to the apparatus 2200 can be provided, at least partially, by applying a differential fluid pressure to the embryonic web 543. Referring to Figure 4, the embryonic web 543 can be vacuum transferred from the forming element 1600 to the apparatus 2200 by a vacuum source 600, shown in Figure 4, such as a vacuum shoe or a vacuum roller. One or more additional sources of vacuum 620 may also be provided downstream of the transfer point of the embryonic web to provide additional dewatering. The web 545 is transported over the apparatus 2200 in machine direction (MD) in Figure 4) to a point or grip line 800 provided between a vacuum pressure roll 900 and a hard surface 875 of a Yankee 880 heated drum dryer . Referring to Figure 9, just upstream of the gripping point or line 800 a steam bell 2800 may be placed. The steam bell may be used to direct the steam over the surface 549 of the web 545, according to the surface 547 of the 545 weft is transported on the pressure roller Vacuum P1001 900. The steam bell 2800 is mounted opposite to a section of the portion 920 that provides vacuum of the vacuum pressure roller. The vacuum-providing portion 920 sucks the vapor into the web 545 and the felt layer 2220. The steam provided by the steam hood 2800 heats the water in the paper web 545 and the felt layer 2220, thereby reducing the viscosity of the water in the weft and felt layer 2220. Accordingly, the water in the weft and felt layer 2220 can be removed more easily by the vacuum provided by the roller 900. The steam hood 2800 can provide approximately 0.3 pounds of saturated vapor per pound of dry fibers at a pressure less than about 15 psi. The portion 920 that provides the vacuum provides a vacuum of between about 1 and about 15 inches of Mercury and, preferably, between about 3 and about 12 inches of Mercury at the surface 2204. A suitable vacuum pressure roll 900 is a roll of pressure with suction, manufactured by Winchester Roll Products. A suitable 2800 vacuum hood is the D5A model manufactured by the Measurex-Devron Company of North Vancouver, British Columbia, Canada.
P1001 The portion 920 that provides vacuum is in communication with a vacuum source (not shown). The vacuum-providing portion 920 is stationary with respect to the rotating surface 910 of the roller 900. The surface 910 may be a perforated or slotted surface through which vacuum is applied to the surface 2204. The surface 910 rotates in the direction that is shown in Figure 9. Vacuum providing portion 920 provides a vacuum on surface 2204 of weft support apparatus 2200, as the weft and apparatus 2200 are transported through steam field 2800 and through the point or gripping line 800. While a single portion 920 providing vacuum is shown, in other embodiments it may be desirable to provide separate vacuum providing portions, each providing a different vacuum on the surface 2204, as the apparatus 2200 travels around the roll 900. The Yankee dryer typically comprises an iron drum or steel heated with steam. Referring to Figure 9, the frame 545 is conveyed to the point or grip line 800 supported on the apparatus 2200, such that the second, virtually smooth face 549 of the frame can be transferred to the surface 875. Upstream of the point or grip line, before P1001 point where the web is transferred to the surface 875, a nozzle 89 applies adhesive to the surface 875. The adhesive can be an adhesive based on polyvinyl alcohol. Alternatively, the adhesive may be CREPTROL® brand adhesive, manufactured by Hercules Company of Wilmington Delaware. Other adhesives can also be used. In general, for embodiments wherein the web is transferred to the Yankee drum 880 to a consistency greater than about 45 percent, a creping adhesive based on polyvinyl alcohol can be used. At consistencies of about 40 percent, an adhesive such as the CREPTOL® adhesive can be used. The adhesive can be applied directly to the weft or, indirectly (such as by application to the surface 875 of the Yankee), in various forms. For example, the adhesive can be sprayed in the form of micro droplets on the weft or on the surface 875 of the Yankee. Alternatively, the adhesive could also be applied to the surface 875 by a transfer roller or brush. In yet another embodiment, the creping adhesive could be applied to the pulp at the wet end of the papermaking machine, such as, for example, by adding the adhesive to the pulp in the head tub 500. Approximately 2 can be applied.
P1001 pounds to approximately 4 pounds of adhesive per ton of dry paper fibers in the Yankee 880 drum. As the weft is transported in the 2200 apparatus through the 800 grip line, the portion 920 providing vacuum of the roller 900 provides a vacuum at the surface 2204 of the weft support apparatus 2200. Also, as the web is transported in the apparatus 2200 through the grip line 800, between the vacuum pressure roller 900 and the surface of the dryer 800 [sic], the pattern modeling layer 2250 of the support apparatus 2200 The first side 547 of the weft 545 is provided with the pattern corresponding to the surface 2260. Because the second side 549 is a macroscopically monoplane and practically smooth face, virtually the entire second surface 549 is placed against the surface 875. of the dryer and adheres thereto, as the web is conveyed through the grip line 800. As the web is conveyed through the grip line, the second face 549 is supported or supported against the smooth surface 875 stay in a macroscopically flat and practically smooth configuration. According to the foregoing, a first predetermined pattern or pattern can be imparted to the first surface 547 of the frame 545, while the second face 549 remains practically smooth. The plot P1001 545 preferably has a consistency of between about 20 percent and about 60 percent when the web 545 is transferred to the surface 875 and the surface pattern 2260 is imparted to the web to densify the web selectively . The pattern or pattern of the surface 2260 is imparted to the frame to provide the continuous network region 110 and the discrete regions 130 of relatively low density, shown in Figures 1 to 3. Without being limited by theory, it is believed that, as a result of having virtually the entire second face 549 placed against the surface 875 of the Yankee, drying of the weft 545 on the Yankee is more efficient than would be possible with a weft having only selective portions of the second face against the Yankee . The final step in the formation of the paper structure 20 comprises creping the web 545 from the surface 875 with a doctor blade, also known as doctor blade 1000, as shown in Figure 4. Without being limited by theory, it is believed that the energy imparted by the scraper blade 1000 to the frame 545 gives it volume or dedensifies at least some portions of the frame, especially those portions of the frame that are not printed by the pattern modeling surface 2260, such as the regions 130 and 280 of relatively density P1001 low. Accordingly, the step of creping the web from the surface 875 with the doctor blade 1000 provides a web having a compacted first, relatively thin region corresponding to the pattern imparted to the first face of the web and a web. second region relatively thicker. In one embodiment, the scraper blade has a chamfer angle of approximately 20 degrees and is positioned with respect to the Yankee dryer to provide an impact angle of approximately 76 degrees. The following examples illustrate the practice of the present invention but are not intended to limit it.
EXAMPLE 1: First, an aqueous pulp was prepared at 3% by weight of Softwood Kraft fibers or Northern Softwood Kraft (NSK), using a conventional repulper. To the NSK raw material tube was added a 2% solution of the resin for temporary wet strength (ie, PAREZ® 750 marketed by American Cyanamid Corporation of Stanford, CT) at a ratio of 0.2% by weight of the fibers dry. The NSK pulp was diluted to a consistency of about 0.2% in the fan pump. Secondly, an aqueous pulp of Eucalyptus fibers at 3% by weight was prepared, using a P1001 conventional repulper. To one of the tubes of the Eucalyptus raw material was added a 2% solution of the unraveling agent (ie, Adogen® SDMC marketed by Witco Corporation of Dublin, OH) at a ratio of 0.1% by weight of the dry fibers. The eucalyptus pulp was diluted to a consistency of approximately 0.2% in the fan pump. The treated paper streams are mixed in the head tub and deposited on the forming element 1600. The dewatering takes place through the forming element 1600 and is aided by a baffle and by vacuum boxes. The forming element 1600 includes protrusions 1659 attached to a reinforcing structure 1657. The reinforcing structure is a mesh made by Appleton Wire of Appleton, Wisconsin, having a triple-layer square weft configuration having 90 monofilaments in machine direction and 72 monofilaments in the cross-machine direction, respectively. The diameter of the monofilament varies from about 0.15 mm to about 0.20 mm. The mesh reinforcement structure has an air permeability of approximately 1050 scfm. The forming element 1600 has approximately 100 protrusions 1659 per square inch. The protuberances 1659 have the shape shown in Figure 5 P1001 and have an A MD dimension (machine direction) of 0.105 inch, a B CD dimension (cross-machine direction) of approximately 0.074 of an inch, a distance C in the direction of a magnum of 0.136 of an inch and a separation D in a cross machine direction of 0.147 inches. The minimum separation E between adjacent protuberances can be 0.029 inch. The protuberances 1659 extend a height H of about 0.008 inch. The openings 1663 have an elliptical shape with the major axis parallel to the machine direction of approximately 0.052 inches and in minor axis of approximately 0.037 inches. The upper surface of the protuberances 1659 provide approximately 35 percent of the projected area of the forming element 1600, as seen in Figure 5. The openings 1663 provide approximately 15 percent of the projected area of the forming element 1600, as seen in the Figure 5. The angles 1665 provide approximately 50 percent of the projected area of the forming element 1600, as seen in Figure 5. The embryonic web is transferred from the forming element 1600, to a fiber consistency of about 10% at the point of transfer, to a frame support apparatus 2200 having a layer 2220 of P1001 dewatering felt and a 2250 layer of photosensitive resin pattern modeling. Dewatering felt 2220 is an Amflex 2 Press Felt manufactured by Albany International of Albany, New York. The felt 2220 comprises a tow of polyester fibers. The tow has a surface denier of 3 and a substrate denier of 10 to 15. The felt layer 2220 has a basis weight of 1436 g / square meters, a gauge of about 3 millimeters and an air permeability of about 30 to about 40 scfm. The pattern modeling layer 2250 comprises a continuous network surface 2260 that contacts the pattern, with approximately 69 discrete apertures 2270 per square inch, the apertures having the shape shown in FIG. 7. The pattern modeling layer 2250 is shown in FIG. The frame has a projected area equal to approximately 35 percent of the projected area of the frame support apparatus 2200. The elevation difference 2261 of the surface 2260 and the elevation 2231 of the felt layer 2230 is approximately 0.008 inches (0.205 millimeters). The embryonic web is transferred to the web support apparatus 2200 to form a generally monoplane web 545. The transfer and deflection are provided at the vacuum transfer point with a differential pressure of approximately 20 inches of P1001 mercury. Additional dewatering is achieved by assisted or vacuum assisted drainage, until the weft has a fiber consistency of approximately 25%. The weft 545 is conveyed to the grip line 800. The vacuum roll 900 has a compression surface 910 having a hardness of about 60 P &J. The web 545 is compacted against the compaction surface 875 of the Yankee dryer drum 880 by pressing the web 545 and the web support apparatus 2200 between the compression surface 910 and the surface of the Yankee dryer drum 880 at a compression pressure of about 200 psi. The creping adhesive based on polyvinyl alcohol is used to adhere the compacted web to the Yankee dryer. The fiber consistency is increased to at least about 90% before dry creping the weft with a scraper blade. The doctor blade has a chamfer angle of about 20 degrees and is positioned with respect to the Yankee dryer to provide an impact angle of approximately 76 degrees; The Yankee dryer is operated at approximately 800 fpm (feet per minute) (approximately 244 meters per minute). The dry weft becomes a roll at a speed of 650 fpm (200 meters per minute). The plot becomes a tissue paper for homogeneous two-leaf bath. Toilet paper with two sheets P1001 has a basis weight of approximately 25 pounds per 3000 square feet and contains approximately 0.2% of the resin for temporary wet strength and approximately 0.1% of the unraveling. The resulting two-ply tissue paper is bulky, soft, absorbent, aesthetic and is suitable for use as toilet paper or as a disposable tissue.
EXAMPLE 2 Prophetic Example In accordance with this prophetic example, an aqueous pulp of Northern Softwood Kraft fibers was prepared (NSK), at 3% by weight using a conventional repulper.
A solution was added to the NSK raw material tube 2% resin for temporary wet strength (ie, PAREZ® 750, marketed by American Cyanamid corporation of Stanford, CT) in a proportion of 0.2% by weight of the dry fibers. The NSK pulp was diluted to a consistency of about 0.2% in the fan pump. Second, an aqueous pulp of 3% by weight Eucalyptus fibers was prepared using a conventional repulper. To one of the eucalyptus raw material tubes was added a 2% solution of the unraveling agent (ie, Adogen® SDMC, marketed by Witco Corporation of Dublin, OH) in a proportion of 0.5% by weight of the P1001 dry fibers. This first Eucalyptus pulp was diluted to a consistency of about 0.2% in the fan pump. Third, an aqueous pulp of 3% by weight Eucalyptus fibers was prepared using a conventional repulper. To the Eucalyptus raw material tube was added a 2% solution of the unraveling agent (ie, Adogen® SDMC, marketed by Witco Corporation of Dublin, OH) and a 2% solution of the binder for dry strength (i.e. Redibond® 5320, sold by National Starch and Chemical Corporation of New York, New York) in a proportion of 0.1% by weight of the dry fibers. This second eucalyptus pulp was diluted to a consistency of about 0.2% in the fan pump. From the previous pulps three individual treated paper streams were formed. Stream 1 is a mixture of the NSK pulp and the second Eucalyptus pulp, stream 2 is formed from the first eucalyptus pulp (eucalyptus 100 percent unlinked) and stream 3 is a mixture of the NSK stream and the first eucalyptus pulp. The three paper streams were deposited on the forming element 1600 to form a three layer weave having external layers comprising a mixture of NSK and Eucalyptus and an inner layer P1001 comprising unlinked eucalyptus. The dewatering occurs through the forming element 1600 and is aided by a deflector and by vacuum boxes. The reinforcing structure 1657 of the forming element is a mesh, manufactured by Appleton Wire of Appleton, Wisconsin, having a three-layer square weft configuration having 90 monofilaments in the machine direction and 72 monofilaments in the cross machine direction, inch, respectively. The diameter of the monofilament varies from about 0.15 mm to about 0.20 mm. The reinforcing structure has an air permeability of about 1050 scfm. The protuberances 1659 have a size and shape are formed as shown in Figure 5. The protuberances have the same overall dimensions as set forth above for Example 1, except that the openings 1663 are of reduced size to provide only about 10 percent of the projected area as seen in Figure 5. The height H shown in Figure 6 is approximately 0.008 inches (0.152 millimeters). The size of the openings was reduced to provide a weft that generally has two regions 40 and 60 of basis weight and without a region of intermediate basis weight. The embryonic plot is transferred from the P1001 forming element 1600, at a fiber consistency of about 10% at the transfer point, to a weft support apparatus 2200 having a layer 2220 of dewatering felt and a layer 2250 of modeling the photosensitive resin layer. Dewatering felt 2220 is an Amflex 2 Press Felt manufactured by Albany International of Albany, New York. The felt 2220 comprises a tow of polyester fibers. The tow has a surface denier of 3, a substrate denier of 10 to 15. The felt layer 2220 has a basis weight of 1436 g / square meters, a gauge of about 3 millimeters and an air permeability of about 30 to about 40 scfm. The pattern modeling layer 2250 comprises a continuous network surface 2260 that contacts the pattern, with discrete apertures 2270 having the shape shown in Figure 7. The pattern modeling layer 2250 has a projected area equal to about 35 percent of the projected area of the frame support apparatus 2200. The elevation difference 2261 of the surface 2260 and the elevation 2231 of the felt layer 2230 is approximately 0.008 inches (0.205 millimeters). The embryonic web is transferred to the web support apparatus 2200 to form a generally monoplane web 545. The transfer and deflection are P1001 provide at the vacuum transfer point with a differential pressure of approximately 20 inches of mercury. The additional dewatering is achieved by vacuum-assisted drainage, until the weft has a fiber consistency of approximately 25%. The weft 545 is transported or carried to the grip line 800. The vacuum roll 900 has a compression surface 910 having a hardness of about 60 P &J. The web 545 is compacted against the compaction surface 875 of the Yankee dryer drum 880 by pressing the web 545 and the web support apparatus 2200 between the compression surface 910 and the surface of the Yankee dryer drum 880 at a compression pressure of about 200 psi. The creping adhesive based on polyvinyl alcohol is used to adhere the compacted web to the Yankee dryer. The fiber consistency is increased to at least about 90% before dry creping the weft with a scraper blade. The doctor blade has a chamfer angle of about 20 degrees and is positioned with respect to the Yankee dryer to provide an impact angle of approximately 76 degrees; The Yankee dryer is operated at approximately 800 fpm (feet per minute) (approximately 244 meters per minute). The dry weave is transformed into a roll at a speed of 650 fpm (200 meters per minute).
P1001 The weft becomes a tissue paper for three-layer and two-sheet bath. The two-sheet toilet paper has a basis weight of approximately 25 pounds per 3000 square feet and contains approximately 0.2% of the resin for temporary wet strength and approximately 0.1% of the destabilizer. The resulting two-ply tissue paper is bulky, soft, absorbent, aesthetic and is suitable for use as toilet paper or as a disposable tissue.
TEST METHODS: Surface Smoothness: The surface smoothness of one side of a paper web is measured based on the method for measuring physiological surface smoothness (PSS) exposed in the 1991 International Paper Physics Conference, TAPPI Book 1, in the article entitled "Methods for the Measurement of the Mechanical Properties of Tissue Paper" by Ampulski et al., Found on page 19, the article is incorporated herein by reference. The measurement of the PSS as used herein is the point-by-point sum of the amplitude values as described in the previous article. The measurement procedures described in the article are also described in general terms in the Patents of the P1001 United States No. 4,959,125 issued to Spendel and No. 5,059,282 issued to Ampulski et al., Whose patents are incorporated herein by reference. In order to test the paper samples of the present invention, to measure the surface smoothness the method was used to measure the PSS of the previous article, with the following modifications to the procedure: Instead of importing pairs of digitized data (amplitude and time) ) in the 10-sample SAS software, as described in the previous article, the measurement of the Surface Smoothness was made by acquiring, digitizing and statistically processing the data of 10 samples, using the software LABVIEW brand that is obtained from National Instruments of Austin , Texas. Each amplitude spectrum is generated using the "Amplitude and Phase Spectrum.vi" module of the LABVIEW software package, where "Spec Spectrum Mag Vrms" was selected as the output spectrum. An output spectrum was obtained from each of the 10 samples. Each output spectrum was then smoothed using the following weight or weighting factors in the LABVIEW: 0.000246, 0.000485, 0.00756, 0.062997. These weight or weighting factors were selected to mimic the smoothing provided by the factors 0.0039, 0.0077, .120, 1.0, specified in the previous article P1001 for the SAS program. After smoothing, each spectrum was filtered using the frequency filters specified in the previous article. The value of PSS, in microns, is then calculated, as described in the aforementioned article, for each individually filtered spectrum. The Surface Smoothness of the side of a paper web is the average of the 10 measured PSS values of the 10 samples taken from the same side of the paper web. Similarly, the Surface Smoothness of the opposite side of the paper web can be measured. The smoothness ratio is obtained by dividing the upper value of the Surface Smoothness that corresponds to the more textured side of the paper web between the lower value of the Surface Smoothness that corresponds to the softer side of the paper web.
Base Weight: The basis weight of the frame (macro or macroscopic basis weight) was measured using the following procedure: The paper to be measured is conditioned at 71-75 degrees Fahrenheit at a relative humidity of 48 to 52 percent during a minimum of 2 hours. The conditioned paper is cut to provide twelve samples that P1001 measures 3.5 inches by 3.5 inches. The samples are cut, six samples at a time, with a suitable pressure plate cutter, such as a Thwing-Albert Alfa Hydraulic Pressure Sample Cutter, Model 240-10. The two stacks of six samples were then combined in a stack of 12 sheets and conditioned for at least 15 additional minutes at a temperature of 71 to 75 degrees F and at a humidity of 48 to 52 percent. The 12-hour battery was then weighed on a calibrated analytical balance. The balance is kept in the same room in which the samples were conditioned. A suitable scale is manufactured by Sartorius Instrument Company, Model A200S. This weight is the weight in grams of a stack of 12 sheets of paper, each sheet has an area of 12.25 square inches. The basis weight of the paper web (the weight per unit area of a single sheet) is calculated in units of pounds per 3,000 square feet, using the following equation: Weight of the stack of 12 sheets (grams) x 3000 x 144 square inches per square foot. (453.6 g / lb) x (12 sheets) x (12.25 in. Square, per sheet) or simply: Weight Base (Ib / 3, 000 ft2) = Weight of the stack of 12 sheets (g) x 6.48 P1001 Measurement of Weft Support Apparatus Elevations: The difference in elevation between the elevation 2231 of the first felt surface and the elevation 2261 of the surface 2260 that makes contact with the weft is measured using the following procedure: frame support is supported on a flat horizontal surface where the pattern modeling layer is oriented upwards. A style that has a circular contact surface of approximately 1.3 square millimeters and a vertical length of approximately 3 millimeters is mounted on a Federal Products sizing gauge (model 432B-81 amplifier modified for use with a EMD-4320 Wl rupture probe) manufactured by Federal Products Company of Providence, Rhode Island. The instrument was calibrated by determining the voltage difference between two precision shims of known thickness, which provide a known elevation difference. The instrument is zeroed at a slightly lower elevation than the first felt surface 2230 to ensure unrestricted style travel. The style is placed on the elevation of interest and is lowered to perform the measurement. The style exerts a pressure of approximately 0.24 grams / square millimeter at the measurement point. At each elevation, P1001 perform at least three measurements. The measurements at each elevation are averaged. The difference between the average values is calculated to provide the elevation difference.
P1001

Claims (18)

  1. CLAIMS: 1. A paper web comprising: at least two regions of different basis weight arranged in a first non-random repeat pattern; at least two regions of different density arranged in a second non-random repeat pattern; And where the first and second patterns combine to provide a visually distinguishable third pattern, the third pattern is different from the first and second patterns.
  2. 2. The paper web according to claim 1, wherein the third pattern comprises a multitude of first flutes. The paper web according to claim 2, wherein the third pattern comprises a multitude of second grooves and, wherein, at least some of the first grooves intersect at least some of the second grooves. 4. The paper web according to claim 3, wherein the first and second ribs extend diagonally with respect to the machine direction and the cross machine direction of the paper web. 5. The paper web according to claim 4, P1001 wherein the first and second ridges intersect to provide a multitude of generally diamond-shaped cells. The paper web according to claims 1, 2, 3, 4 or 5, wherein the first pattern comprises a region with essentially continuous network basis weight, wherein the second pattern comprises a region with essentially continuous network density and , wherein, the region with continuous basis weight of net and the region with continuous network density interfere to provide a third visually distinguishable pattern. 7. A non-through air dried paper web comprising at least two regions of different density, arranged in a non-random repeat pattern and at least two regions of different basis weight disposed in a non-random repeat pattern. 8. The paper web according to claims 1,2,3,4,5 or 7, wherein the at least two regions of different density comprise an essentially continuous network region of relatively high density. 9. The paper web according to claims 1,2,3,4,5,6 or 7, wherein the at least two regions of different density comprise a multitude of discrete, spaced, relatively low density regions, dispersed throughout the network region essentially continuous P1001 and of relatively high density. 10. The paper web according to claims 1,2,3,4,5,7,8 or 9, wherein the at least two regions of different basis weight comprise an essentially continuous network region of relatively high basis weight. The paper web according to claims 1,2,3,4,5,7,8,9 or 10, wherein the at least two regions of different basis weight comprise a multitude of discrete regions of relatively low base weight dispersed throughout the continuous network of relatively high basis weight. 12. The paper web according to claims 1,2,3,4,5,6,7,8,9,10 or 11, comprising at least three regions of different basis weight. 13. The paper web according to claims 1,2,3,4,5,6,7,8,9,10,11 or 12, wherein the paper web comprises a multitude of discrete regions of intermediate weight and , wherein the intermediate basis weight regions are generally circumscribed by the relatively low basis weight regions. 14. A method for producing a non-through air dried paper web having at least two regions of different basis weight and at least two regions of different density, the method comprising the steps of: providing a multitude of fibers suspended in a carrier liquid; P1001 provide a fiber retention forming element having liquid permeable zones; depositing the fibers and the liquid carrier on the forming element; draining the liquid carrier through the forming element in at least two simultaneous stages to form a web having at least two regions of different basis weight; providing a weft support apparatus comprising a surface for applying a pattern to the weft, that is, for modeling the weft, and a layer of weathered wipe; transferring the web from the forming element to the weft modeling surface of the weft support apparatus; selectively densifying a portion of the weft to provide the weft at least two different densities. The method according to claim 14, wherein the step of selectively densifying a portion of the frame comprises providing a continuous network region of relatively high density and a multitude of discrete regions of relatively low density, dispersed throughout the region of continuous network of relatively high density. P1001 16. The method according to claim 14 or 15, wherein the step of draining the liquid carrier through the forming member comprises forming a weft having a relatively high continuous basis weight network and a plurality of discrete regions of relatively low basis weight. low, dispersed throughout the continuous network of relatively high basis weight. 17. The method according to claim 14, 15 or 16, wherein the step of draining the liquid vehicle through the forming element comprises forming a web having at least three different base weights. 18. The method according to claim 14,15,16 or 17, wherein the step of draining the liquid carrier through the forming element comprises forming a web having a relatively high continuous base web region; a plurality of discrete regions of relatively low basis weight, dispersed throughout the continuous network region of relatively high basis weight and a multitude of discrete regions of intermediate basis weight, circumscribed by relatively low basis weight regions. P1001
MXPA/A/2000/001835A 1997-08-22 2000-02-22 Paper structures having different basis weights and densities MXPA00001835A (en)

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