MXPA00009042A - Apparatus and process for making structured paper and structuredpaper produced thereby - Google Patents

Abstract

An apparatus and process for imprinting a web. A yankee drum (70) and pressure roll (35) are juxtaposed to form a nip. An imprinting member (30), such as through air drying belt or other patterning belt is interposed in the nip. A felt (60) is also interposed in the nip, contacting the backside of the imprinting member. The imprinting member carries a paper web (32). The paper web is imprinted in the nip and simultaneously transferred to the yankee drying drum. The nip may be formed with a vacuum roll juxtaposed with the felt. The vacuum roll may remove water from the felt and hence the web.

Description

APPARATUS AND PROCESS FOR DEVELOPING A STRUCTURED PAPER AND STRUCTURED PAPER PRODUCED IN THIS FORM FIELD OF THE INVENTION The present invention relates to the production of paper and more particularly to the production of paper having regions of different characteristics, such as density, thickness, crepe, amplitude, etc. BACKGROUND OF THE INVENTION Papermaking is a well-known technique. To make paper, cellulose fibers and a liquid vehicle are mixed. The liquid vehicle is drained and the embryonic tissue resulting from cellulose fibers is dried. Drying is typically achieved in one of two ways, through either through-air drying or through conventional drying. Pass-through drying is based on blowing warm air through the embryonic tissue. Conventional drying is based on a press felt to remove water from the fabric by capillary action. Drying with through air produces a paper having regions of different densities. This type of paper has been used in commercially successful products such as, for example, Bounty paper towels and the Charmin and Char in Ultra brands of bath tissues. However, there are situations or situations in which you do not want to use air drying.

In these situations, conventional felt drying is used. However, conventional felt drying does not necessarily produce the structured paper or its collateral advantages. Accordingly, it has been desired to produce a structured paper using conventional felt drying. This has been achieved by using a conventional felt having a pattern-like structure for embossing the embryonic tissue. Examples of attempts of this type include the commonly assigned North American Patents number 5, 556, 509, issued September 17, 1996 to Trokhan et al .; No. 5,580,423, issued December 3, 1996 to Ampulski et al .; number 5,609,725, issued on March 11, 1997 to Phan; No. 5,629,052, issued May 13, 1997 to Trokhan et al .; No. 5,637,194, issued June 10, 1997 to Ampulski et al .; number 5,674,663, issued on October 7, 1997 to McFarland et al .; and number 5,709,775 issued on the 20th day January 1998 to Trokhan et al, whose disclosures are incorporated herein by reference. However, there are cases in which one wishes to employ a conventional felt without a pattern structure, said flexibility in the manufacturing process being provided in the present invention. The North American Patent No. 4,421,600 issued on December 20, 1983 to Hostetler discloses an apparatus having two felts and three pressing operations. Again, after pressing, the fabric is transferred on a woven print fabric to the Yankee dryer. An attempt of this type in the art is illustrated by US Pat. No. 4,309,246 issued on January 5, 1982 to Hulit et al. Hulit et al. describe three configurations where a narrowing between two rollers is formed. In each configuration, a patterned fabric and a felt are interposed between two rollers. A paper fabric is worn on the embossing fabric and is printed by the embossing fabric. Hulit then carries the fabric from this narrowing in the embossing fabric. In two modes, Hulit transfers the fabric from the stamping fabric to a Yankee drying drum. In the third mode, Hulit does not employ a Yankee drying drum. The arrangement of Hulit has numerous disadvantages. First, two sets of nip, a first nip to stamp the fabric and a second nip where the fabric is transferred to the Yankee drying drum are required. Hulit recognizes that dryer drums can be used in place of the Yankee drying drum or in addition to said Yankee drying drum. Nevertheless, Hulit does not minimize the expense and discomfort of requiring two separate constrictions for the configurations that are based on the Yankee drying drum - as is most commonly the case in the art. In addition, by stamping the tissue in the first operation, and transferring the tissue from paper to a Yankee dryer tab in a second operation, Hulit creates a thickness in one operation which it destroys in a subsequent operation. The compaction of the Hulit fabric necessarily occurs between the compression roller and the Yankee dryer. This compaction destroys the thickness that was formed by stamping the fabric in the first room. Another attempt is shown in European Patent 0 526 592 Bl issued on April 5, 1995 to Erikson et al. Erikson et al. disclose another configuration of two narrowings. In the first narrowing, the paper is stamped between a press roll and a lower press roll. There, Erikson et al. Dehydrate the paper by placing the press felt directly against the paper. This allows the press felt to deform in the areas of the embossing fabric not supported by ball joints, which reduces the differential density effects of compaction caused by the embossing fabric. Erikson stamps the paper and transfers it to the Yankee dryer on a lower press roll. The paper is transferred to the Yankee dryer drum at this point. However, the second press drum stamps the paper again. The problem presented by Erikson et al. is that in its second narrowing the stamping strap never corresponds to the stamping pattern provided in the first narrowing. Thus, Erikson improperly compacts the paper and destroys the thickness it creates by stamping it in the first narrowing. In addition, Erikson et al., Like the aforementioned attempts in the art, still requires a complex system of two narrowings. Erikson also requires that the press felt strip be outside the printing cloth loop. This arrangement creates a very expensive proposal to retrofit existing machinery, since space, transmissions, etc. are required. additional to add the separate felt gauze. The cost of installing such a separate felt strip on an existing papermaking machine is estimated at more than $ 10 million. US Pat. No. 5,637,194 assigned in a joint manner granted on June 10, 1997 to Ampulski et al., The disclosure of which is incorporated herein by reference, presents a modality of an alternative paper making machine where a felt adjacent to one side of the paper is placed. stamping member. The stamping members stamp the molded fabric and carry it to the Yankee drying drum. Ampulski et al. they indicate that the stamping member can be used for a through-air drying and the fabric is molded into the stamping member. While Ampulski et al. represent a significant improvement compared to the prior art, Ampulski et al. they do not provide full fabric contact against the Yanquee drying drum. COMPENDIUM OF THE INVENTION _ _ _ The invention comprises an apparatus for making paper. The apparatus has a first rigid surface and a second rigid surface juxtaposed to form a constriction therebetween. A stamping member is placed in the constriction and carries a tissue. The stamping member has a blade side to be in contact with the fabric and an opposite back side. The fabric is in a contact relationship with the first rigid surface so that the fabric can be simultaneously stamped and transferred to the first rigid surface. A capillary water removal member also intervenes in the constriction and is in contact with the second rigid surface and with the back side of the stamping member. A compression force can be applied simultaneously on the tissue, the stamping member and the capillary member of water removal through narrowing. In a preferred embodiment, the constriction is formed through two coaxial rollers. One of the rollers can be a Yankee drying drum, the other roller can be a pressure roller and more preferably a vacuum pressure roller. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a vertical side elevation view of a papermaking machine in accordance with the present invention. Figure 2 is a fragmentary top plan view of the embossing member illustrated in Figure 1. Figure 3 is a vertical cross-sectional view along line 3-3 of Figure 1. Figure 4 is a view in fragmentary vertical side elevation of an alternative embodiment of a papermaking machine in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION _ With reference to Figure 1, the present invention begins with an aqueous dispersion of fibers deposited in a head box 10 as is known in the art. The aqueous fiber dispersion provides a paper 20 which may be of constant base weight or may comprise several base weights. If desired, the paper may have several base weights. Preferably, the paper 20 of several base weights has two or more different regions: regions with a relatively high basis weight and regions with a relatively low basis weight. Preferably, regions with a high basis weight comprise an essentially continuous network. Regions with a low base weight may be discrete. If desired, the paper 20 according to the present invention may also comprise intermediate base weight regions placed within the low base weight regions. A paper of this type can be made in accordance with the United States Patent 5,245,025, issued September 14, 1993 to Trokhan et al., The disclosure of which is incorporated herein by reference. If the paper 20 has only two different base weight regions, a substantially continuous high basis weight region with discrete low base weight regions placed in the essentially continuous high basis weight region, said paper 20 can be made from in accordance with the joint United States Patents 5, 527, 428 issued on June 18, 1996 to Trokhan et al.; 5,534,326 issued July 9, 1996 to Trokhan et al .; and 5,654,076, issued August 5, 1997 to Trokhan et al .; whose disclosures are incorporated herein by reference. It may also be desired to increase the density of selected regions of the paper 20. Said paper 20 will have both regions of various densities and regions of several base weights. Said paper 20 can be made in accordance with the United States Patents 5,277,761, issued on January 11, 1994 to Phan et al .; and 5,443,691, issued August 22, 1995 to Phan et al., whose disclosures are incorporated herein by reference. The shaping metal mesh 15 used to produce the paper of several aforementioned base weights 20 may comprise several protuberances. The protuberances protrude from the plane of the shaping metal mesh 15 and are preferably discrete. The protuberances seal the drain through selected regions in the shaping metal mesh 15 producing regions of low and high base weights in the paper 20, respectively. The shaping metal mesh 15 for use with the present invention may be made in accordance with the United States Patents 5,503,715, issued April 2, 1996 to Trokhan et al. and 5,614,061, issued March 25, 1997 to Phan et al., whose disclosures are incorporated herein by reference. The paper is transferred from the shaping metal mesh 15 to a printing belt 30. The embossing belt 30, like the metal shaping mesh 15, is monoplanar on a macroscopic scale. The plane of the embossing belt 30 defines its X-Y directions. Perpendicular to the directions X-Y and to the plane of the embossing belt 30 is the direction Z of the belt 30.

In the same way, the paper 20 according to the present invention can be considered as macroscopically monoplanar and being in a plane X-Y. Perpendicular to the X-Y directions and to the paper plane 20 is the Z direction of the paper 20. The first surface 31 of the embossing belt 30 comes into contact with the paper 20 transported. During papermaking, the first surface 31 of the embossing belt 30 can stamp a pattern on the paper 20 corresponding to the pattern of a structure 42. The second surface 32 of the embossing belt 30 is the surface of the belt 10 that is in contact with the machine. The second surface 32 can be made with a back side network having passages that are distinct from the deflection conduits 46 through the belt 30. The passages give irregularities in the texture of the back side of the second surface 32 of the belt 30. The passages allow an air leak in the XY plane of the belt 30, said leakage does not necessarily flow in the Z direction through the deflection conduits 46 of the belt 30. Alternatively, the embossing belt 30 may have discontinuous ball joints . The discontinuous labels are made by a particular weave of warp and weft yarns. The paper 20 made in said embossing belt will have a similar pattern of discrete patterned areas. Stamping belts which are also used for air drying, and which are known to be suitable for this purpose, are illustrated in co-pending US Patents 3,301,746 issued January 31, 1967 to Sanford et al .; 3,905,863 issued on September 16, 1975 to Ayers; and 4,239,065 issued December 16, 1982 to Trokhan, the disclosure of which is incorporated herein by reference. If desired, the embossing belt 30 employed for the present invention can be woven on a Jacquard loom. The Jacquard loom has supposedly the advantage of offering flexibility to the resulting belt. Examples of woven belts on Jacquard looms are presented in U.S. Patent No. 5,672,248 issued to Farington. Preferably, the embossing belt 30 according to the present invention comprises two primary components, a frame 42 and a reinforcing structure 44. The frame 42 preferably comprises a polymeric resin. The frame 42 and the printing belt 30 have the first surface 31 defining the side in contact with the paper of the core 30 and a second opposite surface 32 facing the paper making machine where the belt 30 is used. , the frame 42 defines a predetermined pattern that stamps a similar pattern onto the paper 20 of the present invention. A particularly preferred pattern for the frame 12 is an essentially continuous network. If the essentially continuous preferred network pattern is selected for the frame 42, discrete conduits 46 will extend between the first surface 31 and the second surface 32 of the embossing belt 30. The essentially continuous network surrounds and defines the conduits 46. The second primary component of the belt 30 according to the present invention is the reinforcing structure 44. The reinforcing structure 44, like the frame 42, has a first side or side facing the paper and a second side or side facing to the machine opposite the surface facing the paper. The reinforcing structure 44 is positioned primarily between the opposing surfaces of the belt 30 and may have a surface corresponding to the back side of the belt 30. The reinforcing structure 44 provides support for the frame 42. The reinforcing structure 44 is typically woven, as is known in the art. The portions of the reinforcing structure 44 which correspond to the deflection conduits 46 prevent the fibers used in the manufacture of the paper from passing completely through the deflection conduits 46 and consequently reduces the presence of holes. If it is not desired to employ a woven fabric for the reinforcing structure 44, a nonwoven element, screen, net, or a plate having several holes and providing adequate strength and support for the frame 42 of the present invention may be employed. The printing belt 30 according to the present invention can be made in accordance with any of the United States Patents jointly: 4,514,345, issued April 30, 1985 to Jonson et al.; 4,528,239, issued on July 9, 1985 to Trokhan; ,098,522, issued on March 24, 1992; 5,260,171, issued November 9, 1993 to Smurkoski et al .; ,275,700, issued on January 4, 1994 to Trokhan et al .; 5,328,565, issued July 12, 1994 to Rasch et al .; 5,334,289, issued on August 2, 1994 to Trokhan et al .; 5,431,786, issued on July 11, 1995 to Rasch et al .; 5,496,624, issued on March 5, 1996 to Stelljes, Jr. et al .; 5,500,277, issued March 19, 1996 to Trokhan et al .; 5,514,523, issued May 7, 1996 to Trokhan et al .; 5,554,467, issued September 10, 1996 to Trokhan et al .; 5,566,724, issued October 22, 1996 to Trokhan et al .; 5,624,790, issued April 29, 1997 to Trokhan et al .; and 5,628,876, issued May 13, 1997 to Ayers et al .; whose disclosures are incorporated herein by reference. Preferably, the frame 42 extends outwardly from the reinforcing structure 44 at a distance of less than about 0.15 millimeters, more preferably less than about 0.10 millimeters and preferably even less than about 0.05 millimeters. With even greater preference, the pattern frame 42 almost coincides with the elevation of the reinforcing structure 44. By having the frame with pattern 42 extending outwards over such a small distance from the reinforcement structure 44, it is It can produce a softer paper. Specifically, this provides for the absence of deviation or molding of paper 20 in the embossing belt 30 as in the prior art. Thus, the resulting paper 20 will have a smoother and less ruby surface. Further, by the fact that the frame 42 extends outwardly from the reinforcing structure 44 over such a short distance, the reinforcing structure 44 will be in contact with the paper in the upper surface pins positioned within the conduits of deflection 46. This arrangement further compacts the paper 20 in the points that coincide with the pins against the Yankee drying drum 70, decreasing the XY spacing between compacted regions. Thus, greater contact between the paper 20 and the Yankee 70 is observed. As noted above, one of the benefits of the present invention is that the impurity of the paper 20 and the transfer to the Yankee drying drum 70 occur simultaneously, eliminating the steps of multiple operations of the prior art. By substantially complete transfer of the paper 20 onto the Yankee drying drum 70 - instead of only with the compacted balls as in the prior art - full contact drying can be obtained. In addition, by simultaneously stamping the paper 20 and transferring it to the Yankee drying drum 70, the thickness is maintained. In the prior art, the stamping is done in a first operation and the transfer to the Yankee drying drum 70 in a second operation. The second operation, with its own separation narrowing, compacts the paper 20 which destroys the thickness provided to the paper 20 in the first narrowing. The present operation stamps and simultaneously transfers the paper thus avoiding this problem. The paper 20 can also be pre-coated, as is known in the art. The pre-engagement can be achieved by subjecting the paper 20 to crepe from a rigid surface, and preferably from a cylinder. A Yankee drying drum 70 is commonly used for this purpose. The crepe is achieved with a blade as is known in the art. The crepe can be achieved in accordance with the joint United States Patent 4,919,756, issued April 24, 1992 to Sawdai, the disclosure of which is incorporated herein by reference. Alternatively, or additionally, shortening can be achieved through a wet microcontact as shown in the joint North American Patent Number 4, 440,597, issued April 3, 1984 to Wells et al, the disclosure of which is incorporated herein by reference. The crepe blade will crepe selectively and differentially into the compacted relatively non-compacted areas of the paper 20. In the present invention, a conventional felt 60 is juxtaposed with the back side of the embossing belt 30. The conventional felt 60 has a structure of surface fiber blocks with a denier less than 5 and preferably less than 3. This surface fiber block structure comes into contact with the embossing belt 30 during papermaking. The felt 60 can have a basis weight of 200 to 1400 grams per square meter. Preferably, the felt 60 does not have a separate pattern there, so that the first surface 31 of the felt 70 is in direct contact with the back side of the embossing belt 30. This contact helps to remove the water from the printing belt 30 and therefore the paper 20. however, if desired, the felt 60 may have a frame with a pattern there, as disclosed in the aforementioned patents which are incorporated herein by reference. It is important that a hydraulic connection be made between the paper 20, the embossing belt 30, and the felt 60. The hydraulic connection can be improved in several ways. First, the felt 60 can be compacted. Compaction of the felt 60 decreases the average pore volume of the felt 60. Preferably, the felt 60 will have an average pore volume distribution of less than 50 microns. A suitable press felt 60 is an Ampfex 2 manufactured by the Appleton Mills Company of Appleton, Wiscosin. Said felt 60 has a thickness of about 2-5 millimeters and a basis weight of 800 to 2000 grams per square meter, and an average density of 0.16 to 1.0 gram per cubic centimeter. The felt 60 can have an air permeability between about 5 and about 300 SCFM per square foot with an air impermeability of less than 50 SCFM per square foot, being preferred for use with the present invention. In addition, to improve the hydraulic connection, the embossing belt 30 may have a block of fired fibers. The fiber block can extend through the surface facing the machine 32 and the surface facing the sheet 31 of the embossing belt 30. More preferably, the fiber block exits out the rear side of the belt 30 in such a way that intimate contact is provided with the felt 60. If desired, the embossing member 30 having the fiber block can be compacted to decrease its average pore volume distribution. Compaction to decrease the pore volume distribution either of a stamping member 30 with fiber blocks 30 or felt 60 can be achieved through a calender narrowing, as is known in the art. Preferably, the average distribution of pore volumes decreases monotonically from the paper 20 to the aggregate stamp member 30 to the capillary felt 60. Said monotonic distribution provides a thermodynamic attraction that aids in removing the water from the paper 20 to be dried. If desired, other capillary water removal members may be employed in place of the felt 60 described above. For example, a foam capillary water removal member may be selected. Preferably, said foam has an average pore size of less than 50 microns. Suitable foams can be made in accordance with the joint US Patent No. 5,260,345 issued on November 9, 1993 to DesMarais et al. and 5,625,222 issued July 22, 1997 to DesMarais et al., the disclosure of which is incorporated herein by reference. Alternatively, an orifice drying limiting means may be employed as a capillary water removal member. Said medium can be made from several sheets superposed in a face-to-face arrangement. The sheets have an interstitial flow area smaller than the flow of the interstitial areas between fibers in the paper. A suitable limitation orifice drying member may be made in accordance with the joint United States Patents 5, 625,961 issued May 6, 1997 to Ensign et al. and 5,274,930 issued on January 4, 1994 to Ensign et al., the disclosure of which is incorporated herein by reference. The felt 60, of the stamping member 30 and the paper 20 are interposed in a constriction. Preferably, the constriction is formed between two coaxial rollers. More preferably, one of the rollers is heated, and preferably even larger, comprises a heated Yankee drying drum 70. The other of the rollers 35 can be a vacuum pressure roller. The felt 60, the embossing belt 30 and the paper 20 interpose in the constriction in such a way that the paper 20 is adjacent to the heated roller, preferably the heated drying drum and more preferably the Yankee drying drum 70. The printing belt 30 is juxtaposed with the paper 20 and in a contact relation with said paper 20. The felt 60 is juxtaposed in a contact relationship with the back side of the embossing belt 30 and the periphery of another roller 35. , or second roller. If desired, a vacuum can be applied through the second roller 35 to the felt. This vacuum assists in the removal of water from the felt 60, and consequently from the paper 20. The second roller 35 can be a vacuum pressure roller. Preferably, a steam box is positioned opposite the steam pressure roller 35. a steam box that injects steam through the paper 20. As the steam passes through the paper 20, it reduces the viscosity of the water contained therein, promoting better drying The vapor is collected by the vacuum pressure roller 35. If desired, a vacuum box can be replaced by the vacuum pressure roller 35. The vacuum box will allow a positive extraction of air, and consequently of water, through the paper 20 in the position in which the paper 20 is transferred to the Yankee drying drum 70. Obviously, a person with ordinary skill in the art will recognize that the simultaneous operations of stamping, water removal and transfer can occur in other than those that require a Yankee drying drum. For example, two flat surfaces may be juxtaposed to form an elongated narrowing between them. Alternatively, two modules can be used, none of which is heated. The rollers may be part of, for example, a calender stack, or an operation that prints a functional additive on the surface of the fabric. Functional additives include: lotions, emollients, dimethicones, softeners, perfumes, mints, etc. which are well known in the art. Referring to Figure 4, if desired, the capillary water removal member 60 may comprise an extended gauze. The extended loop is nested with the swaging member 30 as illustrated in FIG. 1, however, the extended nested loop of FIG. 4 offers the advantage that water removal may occur at the first tapering with subsequent removal of water and transfer occurring in a second narrowing. However, the total number of steps required for the modality of Figure 4 does not increase in comparison to what is shown in Figure 1. A person with ordinary knowledge in the art will recognize that many other variations and changes are feasible . For example, a single roll and an elongated flat surface may be combined to form a constriction between them. However, it is only with the present invention that the three simultaneous functions of water removal from the fabric and / or capillary water removal members can occur by compression, stamping of the fabric, and transfer of the fabric from the stamping member. All these apparatuses and processes are within the scope of the appended claims.

Claims (10)

1. CLAIMS A paper making apparatus, comprising: a first rigid surface and a second rigid surface juxtaposed to form a constriction therebetween; a stamping member that can be placed in said constriction and which carries a tissue there, said stamping member has a blade side to be in contact with a tissue during a papermaking operation and an opposite posterior side; said fabric is in a contact relationship with said first rigid surface, wherein said fabric can be stamped and transferred simultaneously to said first rigid surface; a capillary water removal member that can be interposed in said narrowing in a contacting relationship with said second rigid surface, said capillary water removal member is placed in contact with said back side of said swaging member, so that it can be applying a compression force on said tissue, said embossing member and said capillary water removal member in said constriction.
2. An apparatus according to claim 1, wherein said constriction is formed through two coaxial rollers and juxtaposed to form a constriction therebetween, and preferably where one of said rollers is a Yankee drum.
3. 3. An apparatus according to claim 2, wherein one of said rollers applies a vacuum on said capillary capillary water removal member.
4. 4. An apparatus according to claims 1, 2 and 3, wherein said capillary water removal member comprises a woven felt and preferably said water removing capillary felt has a denier of less than about 5.
5. 5. An apparatus of according to claims 1, 2, 3 and 4, wherein said stamp member comprises a woven belt having a Jacquard fabric.
6. 6. An apparatus according to claim 5, wherein said stamping member comprises a reinforcing structure and a patterned frame placed therein, said patterned frame being oriented towards said tissue while said tissue and said stamping member are in said frame. narrowing.
7. 7. An apparatus according to claim, wherein said patterned frame extends outwardly from said perforated belt, over a distance of less than 0.15 millimeters and preferably over a distance of less than 0.05 millimeters.
8. 8. A papermaking apparatus, comprising: a Yankee drying drum and a pressure roller juxtaposed to form a constriction therebetween, a stamping member, which can be interposed in said constriction, said stamping member comprises a reinforcement element having a patterned frame extending outwardly, said patterned frame comes into contact with said tissue in said constriction and stamps said tissue in said constriction, said fabric being simultaneously in contact and being transferred with said Yankee drying drum in said narrowing; a felt, said felt is juxtaposed with said pressure roller in said narrowing, whereby said felt can remove water from said printing belt in said narrowing. A process for removing water from a fabric, said process comprising the steps providing a first roller and a second roller juxtaposed to form a constriction between them; provide a cellulosic fabric to be dried; providing a stamping member having a sheet side for stamping said fabric and an opposite back side; placing said cellulosic tissue on said stamping member; provide a capillary water removal member; juxtapose said capillary water removal member with said back side of said swaging member; interpose said tissue, said capillary water removal member and said embossing member in said narrowing, whereby a first roller is interposed in said tissue, said capillary water removal member and said embossing member in said narrowing with said tissue in a contacting relationship with said first roller and said capillary water removal member being in contact with the second roller; whereby the water can be removed from said stamping member by capillary action; stamping said fabric with said stamp member; and simultaneously transferring said fabric to said first roller. A process according to claim 9, wherein said paper is printed by a patterned frame with a high density pattern corresponding to said frame, said patterned frame being associated with said stamp member, which preferably comprises a essentially continuous network.