MXPA98008930A - Method and apparatus to manufacture tisu su - Google Patents

Abstract

The present invention relates to a creped tissue sheet having an improved smoothness resulting from the supplemental draining of a wet fabric to a consistency of more than about 30% using non-compressive drainage techniques prior to differential velocity transfer and continuous drying subsequent A particularly suitable air press to provide complementary non-compressive drainage incorporates side and / or end seals to minimize the escape of pressurized fluid

Description

METHOD AND APPARATUS FOR MANUFACTURING SOFT TISSUE Background of the Invention There are many characteristics of tissue products such as bath and facial tissue that must be considered when producing a final product that has desirable attributes that make it suitable and preferred for products for an intended purpose. The improved softness of the product has been a main objective for a long time, and this has been a particularly significant factor for the success of high demand products. In general, the main components of softness include stiffness and volume (density), with lower stiffness and higher volume (lower density), generally improving the perceived softness.

Even though improved softness is a desire of all types of these products, it has been especially challenging to achieve softness improvements in the non-creped continuously dried leaves. Continuous drying provides a relatively non-compressible method for removing water from a fabric by passing warm air through the fabric until the fabric is dry. More specifically, a wet laid fabric is transferred from the forming fabric to a highly permeable and rough continuous drying fabric and is retained on the continuous drying fabric until it dries. The resulting dry tissue is softer and more bulky than a r sheet. crepe dried conventionally because menses are formed and because the tissue is less compressed. So, there are benefits to eliminating the Yankee dryer and doing ur. non-creped continuous drying product. The non-creped continuous drying sheets are typically very rough and unpleasant to the touch, however, in comparison to their creped counterparts. This is partly due to the inherently high stiffness and strength of an un-creped sheet, but it is also partly due to the roughness of the continuous drying fabric over which the wet fabric is shaped and dried.

Therefore, what is missing and required in the art is a method and apparatus for manufacturing tissue products having improved softness and in particular non-creped continuous drying tissue products having improved softness.

Synthesis of the Invention It has now been discovered that an improved non-creped continuous drying fabric can be made by dewatering the fabric to more than about a 30% consistency before transferring the wet fabric from a forming fabric to one or more intermediate transfer fabrics. slower speed before additionally transferring the fabric to a continuous drying cloth for final drying of the fabric. In particular, increasing the consistency of the non-creped continuous dried fabric before the point of the differential speed transfer has surprisingly been found to result in: (1) both superior stress properties in the machine direction and in the transverse direction , contributing to an improved fabric run; and (2) a reduced modulus, which is an increased smoothness, when the tensile strength is adjusted to the normal value. This discovery allows the manufacture of tissue products with a modulus inferior to given tensile strengths in comparison even with the tissue products produced by undergoing a differential velocity transfer at lower consistencies.

Particularly desirable means by which the fabric can be dewatered to a consistency of more than about 30% comprises an air press located just upstream of the differential speed transfer.

While pressurized fluid jets in combination with a vacuum device have been previously discussed in the patent literature, such devices have not been widely used in the manufacture of tissue. Primarily, this appears to be due to the fact that it has not been previously recognized that draining the fabric to more than about 30% consistency in advance of the differential velocity transfer will result in the improved product properties identified herein. further, the lack of incentive to use such equipment is believed to be attributed to the difficulties of the actual implementation, including the disintegration of tissue tissue, pressurized fluid runoff, sealing and / or wear of the fabric and the like. The air press used in the present method overcomes these difficulties and provides a practical apparatus for achieving the desired consistency before differential speed transfer.

Therefore, in one aspect the invention resides in a method for making a soft tissue sheet. The method includes the steps of: depositing an aqueous suspension of fibers to make paper on an endless forming fabric to form a wet fabric; dewatering the wet tissue to a consistency of from about 20 to about 30%; further dewatering the wet fabric using non-compressive dewatering media to a consistency of more than about 30%; transfer the complementary dewatered tissue to a transfer fabric that travels at a rate of from about 10 to about 80% slower than the forming fabric; Transfer the fabric to a continuous drying cloth, and continuously dry the fabric to a final dryness.

The air press desirably provides a pressure difference through the wet fabric of from about 35 to about 60 inches of mercury. This can be achieved in part by a full air of the air press by maintaining a fluid pressure on one side of the wet fabric of from about 5 to about 60 pounds per square inch, and particularly from about 5 to about 100 pounds per square inch. 30 pounds per square inch. The pressurized fluid may be at room temperature, be heated air, vapor c similar. In general, the air press can operate to increase the consistency of the wet fabric by at least about 3 and preferably at least about 5%. Optional steam showers can be used before the air press to increase the consistency of the air press.

Another aspect of the invention resides in an air press for draining a wet fabric. In one embodiment, the air press includes an air plenum comprising a plenum cover having a bottom surface and a vacuum box comprising a vacuum box cover having a top surface positioned in close proximity to the bottom surface of full cover. The air press also includes means for supplying pressurized fluid to the plenum and means for applying vacuum to the vacuum box. The side seal members of the air press are adapted to reside in contact with the air plenum and the vacuum box to minimize the escape of the pressurized fluid. The side seal members are subject to one of the air plenum and the vacuum box, and are positioned in close proximity to the lateral seal contact surfaces defined by the other of the air plenum and the vacuum box. The side seal members are adapted to flex within a sealing contact with the lateral seal contact surface upon exposure to pressurized fluid to improve the effectiveness of the seal.

Optionally, the air press may include a position control mechanism that operates to keep the plenum close to the vacuum box. In particular, the position control mechanism desirably includes a lever mounted rotatably attached to the air plenum, and a counterbalance cylinder attached to the lever. The position control mechanism is adapted to rotate the lever to counter the pressure changes within the air plenum. In this way, the air plenum resides in a close proximity or in contact with the fabrics that pass between the air plenum and the vacuum box, without folding the fabrics between them.

In another embodiment, the air press includes an air plenum comprising a plenum cover having a bottom surface, and means for supplying pressurized fluid to the plenum. The air press also includes a vacuum box comprising a vacuum box cover having a top surface positioned in close proximity to the bottom surface of the plenum cover, and means for applying vacuum to the vacuum box. An arm that is mounted er. Pivotal shape on the air plenum comprises the first and second parts, with the first part of the arm being positioned at least partially inside the air plenum. A sealing bar is formed of or mounted on the first part of the arm. The air press also includes means for pivoting the arm in response to fluid pressure within the air plenum.

In this embodiment, the sealing bar portion of the pivotable arm acts as an extreme seal to prevent the escape of pressurized fluid from between the plenum and the vacuum box. The sealing bar may conform to the irregularities or fabric misalignments of the support structure. The end seals, which sor. also mentioned as CD seals or in the transverse direction, they improve the containment of the pressurized fluid and therefore result in a more efficient operation of the air press. The load of the end seals is controlled to keep the sealing bar in contact with the underlying moving fabric, sir. cause undue wear of the fabric.

The improved results can be obtained sir. sacrifice efficiency. The present method and apparatus will be. able to operate at commercially viable tissue speeds. For example, the forming fabric can be controlled to travel at speeds of at least about 2, OCO feet per minute (fpm), and more desirably at speeds of at least about 4,000 fpm.

The intermediate transfer fabric or fabrics move at a slower speed than the forming fabric during transfer in order to impart stretch to the sheet. As the speed difference between the forming fabric and the slower transfer fabric increases (sometimes referred to as a quick transfer or negative pull), the stretch imparted to the fabric during the transfer is also increased. The transfer fabric can also be relatively smooth and dense compared to the rougher fabric of a typical continuous drying fabric. Preferably the transfer fabric is as fine as it can be run from a practical point of view. The grip of the fabric is achieved by the presence of knuckles on the surface of the transfer fabric. In addition, it may be advantageous if one or more of the transfer fabric fabrics, with or without the presence of a transfer fabric, are achieved using a "fixed separation" or "kiss" transfer in which the fabrics converge and they diverge simultaneously, which is described hereinafter in detail. Such transfers not only prevent a significant compaction of the fabric while it is in a state of wet bond formation, but when used in combination with the smooth transfer fabric and / or differential speed transfer it is observed that they smooth the surface of the fabric. tissue and the final drying sheet.

The speed difference between the forming fabric and the transfer fabric can be from about 10 to about 80% or greater, preferably from about 10 to about 35%, and more preferably from about 15 to about of 25%, with the transfer fabric being the slowest fabric. The optimal speed difference will depend on a variety of factors, including the particular type of product that is being made. As previously mentioned, the increase in the resistance imparted to the tissue is proportional to the speed difference. For a non-creped continuous three-coat cloth or cleaner having a basis weight of about 20 grams per square meter per layer, for example, a speed difference in the production of each layer from about 20 to about 25 % between the forming fabric and a single transfer fabric produces a stretch in the final product of from about 15 to about 20%.

Stretching can be imparted to the fabric using a single differential velocity transfer or two or more differential velocity transfers of the wet tissue before drying. Therefore there may be only one or more fabrics? E transfer. The amount of stretch imparted to the fabric can therefore be divided by 1, 2, 3 or more transfers of differential velocity.

The transfer is desirably carried out so that the resulting sandwich (consisting of the forming fabric / the fabric / the transfer fabric) comes out for as short a duration as possible. In particularit comes out only at the leading edge of the vacuum shoe or the transfer shoe slot that is being used to effect the transfer. In effect, the forming fabric and the transfer fabric converge and diverge at the leading edge of the vacuum groove. The intent is to minimize the distance at which the tissue is in simultaneous contact with both fabrics. It has been found that simultaneous convergence / divergence is the key to eliminating macro-beams and thus improving the smoothness of the resulting fabric or other product.

In practice, simultaneous convergence and divergence of the two fabrics will only occur at the leading edge of the vacuum slot if a sufficient angle of convergence is maintained between the two fabrics as they approach the leading edge of the vacuum slot and if a sufficient angle of divergence is maintained between the two fabrics on the downward side of the vacuum slot. The minimum angles of convergence and divergence are about 0.5 degrees or greater, more specifically about 1 degree or greater, more specifically about 2 degrees or greater, and even more specifically about 5 degrees or greater. The angles of convergence and divergence can be the same or different. The larger angles provide a greater margin of error during the operation. A suitable range is from around 1 degree to around 10 degrees. Simultaneous convergence and divergence is achieved when the vacuum shoe is designed with the tail edge of the vacuum slot being sufficiently recessed relative to the leading edge to allow fabrics to diverge immediately upon passing over the leading edge of the slot of emptiness. This will be described more clearly in relation to the figures.

By placing the machine with the fabrics initially having a fixed spacing to further minimize compression of the fabric during transfer, the distance between the fabrics must be equal to or greater than the thickness or gauge of the fabric so that the fabric is not to be purchased. e significantly when transferred on the leading edge of the vacuum slot.

The increased smoothness is achieved by using the air press upwards of the differential speed transfer. This is most preferably used in combination with a section of fixed separation carrier fabric after drying. The calendering of the fabric is not necessary to obtain the desirable levels of smoothness, but further processing of the sheet, such as by calendering, etching or creping, may be beneficial to further improve the properties of the sheet.

As used herein, the "transfer fabric is a fabric which is placed between the forming section and the drying section of the fabric manufacturing process." The appropriate transfer fabrics are those fabrics for making paper that provide an index. of high fiber support and provide a good vacuum seal to maximize fabric / sheet contact during transfer from the forming fabric The fabric may have a relatively smooth surface contour to impart smoothness to the fabric, but nevertheless must have sufficient texture to grip the fabric and maintain contact during a rapid transfer.The finest fabrics can produce a higher degree of stretch in the fabric, which is desirable for some product applications.

Transfer fabrics include single layer, multi-layer or permeable composite structures. Preferred fabrics have at least some of the following characteristics: (1) on the side of the transfer fabric that is in contact with the wet fabric (the top) the number of yarns in the machine direction (ME per inch (mesh) is from 10 to 200 and the number of threads is er.

The direction transverse to the machine (CD) (count) is also from 10 to 200. The wire diameter is typically smaller than 0.050 inches; (2) On the upper side, the distance between the highest point of the MD knuckle and the highest point of the CD knuckle is from about 0.001 to about 0.02 or 0.C3 inches. Between these two levels, there may be knuckles formed either by MD or CD threads that give the characteristic three-dimensional topography; (3) on the upper side, the length of the knuckles MD is equal to or longer than the length of the knuckles CD; (4) if the fabric is made in a multi-layer construction it is preferred that the bottom layer be of a finer mesh than the top layer as to control the depth of tissue penetration and to maximize fiber retention; and (5) the fabric can be made to show certain geometrical patterns that are pleasing to the eye, which are typically repeated every 2 to 50 warp threads.

Specific suitable transfer fabrics include, by way of example, those made by Asten Forming Fabrics, Inc., of Appleton, Wisconsin and designated with numbers 934, 937, 939, and 959. Particular transfer fabrics that may also be used as well they include the fabrics described in the patent of the United States of North America Nc. 5,429,686 issued July 4, 19956 to Chiu et al., Which is incorporated herein by reference. The void volume of the transfer fabric may be equal to or less than the fabric from which the fabric is transferred.

The forming process and the frame can be conventional as is well known in the papermaking industry. Such a forming process includes the Fourdrinier, roof formers (such as the suction chest roll), separation formers (such as twin wire formers, flood formers), or the like. The forming fabrics or wires may also be conventional, with the finer fabrics with a larger fiber backing being preferred to produce a more smooth fabric or sheet. The head boxes used to deposit the fibers on the forming fabric can be layered or uncoated.

The method described herein can be applied to any tissue of tissue, which includes tissues for facial tissue, bath tissues, paper towels, paper napkins or the like. Such tissue tissues can be single layer products or multi-layer products, such as three layers or four layers or larger. Single layer products are advantageous because of their low manufacturing cost, while multi-layer products may be preferred by many consumers. For multi-layered products it is not necessary that all product layers are the same as long as at least one layer is in accordance with this invention. The fabrics can be layered or uncoated (mixed) and the fibers for making the fabric can be any suitable fibers for making paper.

Suitable base weights for these tissues can be from about 5 to about 70 grams per square meter (gsm), preferably from about 10 to about 40 gsm, and more preferably from about 20 to 40 gsm. around 30 gsm. For a single layer bath tissue, a basis weight of about 25 gsir is preferred. For a two layer fabric, a basis weight of about 20 gsm is preferred. For a three-ply fabric, a basis weight of about 15 gsm per layer is preferred. In general, higher weight basis fabrics will require a lower air flow to maintain the same operating pressure in the full air. The width of the slots in the air press is desirably adjusted to match the system to the available air capacity, with wider slots used for heavier weight basis fabrics.

The drying process may be any non-compressive drying method that tends to preserve the volume or thickness of the wet fabric including, without limitation, continuous drying, infrared irradiation, microwave drying or the like. Due to its commercial availability and practicality, continuous drying is one of the most preferred and known means for non-compressively drying the fabric. Suitable continuous drying fabrics include, without limitation, Asten 920A and 937A, and Velostar P800 and 103A. Continuously dried fabrics may also include those described in U.S. Patent No. 5,429,689 issued July 4, 1995 to Chiu et al. The fabric is preferably dried to a final dryness without creping, since creping tends to lower the strength and volume of the fabric.

Even though the mechanics are not completely understood, it is clear that the transfer cloth and the continuously dried cloth can make independent and separate contributions to the final sheet properties. For example, the smoothness of the surface of the sheet as determined by a perception panel can be manipulated over a wide range by changing the transfer fabrics with the same dried cloth continuously. The tissues produced by the present method and the apparatus tend to be two-sided unless they are calendered. The uncalendered fabrics may, however, be folded together with the sides smooth / rough outward as required by the specific product forms.

Numerous features and advantages of the present invention will be apparent from the following description.

In the description, reference is made to the accompanying drawings which illustrate the preferred embodiments of the invention. Such embodiments do not represent the full scope of the invention. Reference should therefore be made to the claims herein to interpret the full scope of the invention.

Brief Description of the Drawings Figure 1 representatively shows a schematic process flow diagromim illustrating a method and apparatus according to the present invention to form non-creped continuous dried sheets.

Fig. 2 representatively shows an enlarged top plan view of an air press of the process flow diagram of Fig. 1.

Fig. 3 representatively shows a side view of the air press shown in Fig. 2, with parts separated and shown in section for purposes of illustration.

Figure 4 representatively shows an enlarged sectional view taken generally from the plane of line 4-4 of Figure 3.

Figure 5 representatively shows an enlarged sectional view similar to that of Figure 4 but taken generally from the plane of line 5-5 of Figure 3.

Figure 6 representatively shows a side view of an alternate sealing system for the air press shown in Figures 2 and 3, with parts cut away and shown in section for the purposes of illustration.

Fig. 7 representatively shows an enlarged side view of a vacuum transfer shoe shown in Fig. 2.

Figure 8 representatively shows an enlarged side view similar to that of Figure 7 but illustrating the simultaneous convergence and divergence of the fabrics at the leading edge of a vacuum groove.

Figure 9 is a generalized scheme of a load / elongation curve for the tissue, illustrating the determination of the MD inclination.

Detailed description of the invention The invention will now be described in greater detail with reference to the figures. Similar elements in the different figures have been given the same reference numbers for purposes of consistency and simplicity. In all the illustrated embodiments, the conventional papermaking apparatus and operations can be used with respect to the headbox, the forming fabrics, the fabric transfers, drying and creping, all of which will be readily understood by those skilled in the art. of paper making. However, several conventional components are illustrated for purposes of providing the context in which the various embodiments of the invention can be used.

One embodiment of a method and apparatus for manufacturing a tissue is shown representatively in FIG. 1. For simplicity, the various tensioning rollers used schematically to define fabric runs are shown but not numbered. A paper head box 20 injects or deposits an aqueous suspension of paper fibers 21 onto an endless forming fabric 22 traveling around a forming roll 23. The forming fabric 22 allows partial drainage of the freshly formed wet tissue 24. at a consistency of around 10%.

After forming, the forming fabric 22 brings the wet fabric 24 into one or more vacuum or suction boxes 28, which can be used to provide additional drainage of the wet fabric 24 while it is held on the forming fabric 22. In particular, a plurality of vacuum boxes 28 can be used to dewater the fabric 24 to a consistency of from about 20 to about 30%. The illustrated Fourdrinier former is particularly useful for making heavier weight basis sheets useful as cloths and towels, although other forming devices such as twin wire formers, crescent wires or the like may be used instead. Hydro perforation, for example, is described in U.S. Patent No. 5,137,600 issued August 11, 1992 to Barnes et al., Which may optionally be employed to increase the volume of the weave.

The improved drainage of the wet fabric 24 is, however, provided by suitable complementary non-compressive drainage means, for example selected from the group consisting of an air press, infrared drying, microwave drying, sonic drying, continuous drying, and cc drainage. displacement. In the illustrated embodiment, the complementary non-compressive dewatering means comprises an air press 30, described in greater detail hereinafter. The air press desirably elevates the consistency of the wet fabric 24 to more than about 30%, particularly to more than about 31%, more particularly to more than about 32%, and even more particularly to more than about 33%. In particular embodiments, the wet fabric 24 has a consistency leaving the air press 30 and before a subsequent transfer from about 31 to about 36%. In particular embodiments, the air press increases the consistency of the wet fabric 24 by at least about 3 and preferably at least about 5%.

Desirably, a support fabric 32 is brought into contact with the wet fabric 24 in advance of the air press 30. The wet fabric 24 is placed in the form of a sandwich between the support fabric 32 and the forming fabric 22, and therefore it is held during the pressure drop created by the air press 30. Fabrics suitable for use as a support fabric 32 include almost any fabric including forming fabrics such as Albany International 94M.

The wet fabric 24 is then transferred from the forming fabric 22 to a transfer fabric 36 moving at a slower speed than that of the forming fabric in order to impart an increased stretch to the fabric. The transfer is preferably carried out with the aid of a vacuum transfer shoe 37 as described hereinafter with reference to Figures 7 and 8. The surface of the transfer cloth 36 is relatively smooth in order to provide a smoothness to the wet fabric 24. The opening of the transfer fabric 36, as measured by this hollow volume, is relatively low and can be almost equal to that of the forming fabric 22 or even lower.

The transfer fabric 36 passes over the rollers 38 and 39 before the wet fabric 24 is transferred to the continuous drying fabric 40 traveling at about the same speed, or at a different speed if desired. The transfer is effected by a transfer shoe? And vacuum 42, which may be of the same design as that used for the previous transfer. The fabric 24 is dried to a final dryness when the fabric is carried on a continuous dryer 44.

Before being wound onto a spool 48 for a subsequent conversion to the final product form, the dried fabric 50 can be carried through one or more fixed separation fabric holding points formed between the carrier fabrics 52 and 53. The volume or The gauge of the fabric 50 can be controlled by the fabric engraving fastening points formed between the rollers 54 and 55, 56 and 57, and 58 and 59. The suitable carrier fabrics for this purpose are the Albany International 84M or 94M and Asten 959 or 937, all of which are relatively smooth fabrics having a fine pattern. The fastening point spacings between the various pairs of rollers can be from about 0.001 inches to about 0.02 inches (0.025- 0.51 millimeters). As shown, the forming fabric section of the machine is designed and operated with a series of fixed separation points which serve to control the gauge of the fabric and can replace or complement the off-line calendering. Alternatively, a calendered reel can be used to achieve the final gauge or the complement of off-line calendering.

The air press 30 is shown in greater detail by the top view of Figure 2 and the side view of Figure 3, the latter having cut parts for purposes of illustration. The air press 30 generally comprises an upper air plenum 60 in combination with a lower suction or vacuum box 62. The terms "upper" and "lower" are used herein to facilitate reference and understanding of the drawings and they do not want to restrict the way in which the components are oriented. The sandwich of the wet tissue 24 between the forming fabric 22 and the supporting fabric 32 passes between the air plenum 60 and the vacuum box 62.

The illustrated air plenum 60 is adapted to receive a supply of continuous air manifolds of pressurized fluid 64 operatively connected to a source of pressurized fluid such as a compressor or a blower (not shown). The air plenum 60 is provided with a full cover 66 which has a bottom surface 67 which resides during the course in close proximity to the vacuum box 62 and in close proximity to or in contact with the support 52 (figure 3). The full cover 66 is formed with the grooves 68 (FIG. 5) extending perpendicular to the machine direction through essentially the full width of the wet fabric 24 to allow the passage of pressurized fluid from the plenum. 60 through the fabric and wet fabric.

The vacuum box 62 is operatively connected to a vacuum source and fixedly mounted to a support structure (not shown). The vacuum box 62 comprises a cover 70 having an upper surface 72 on which the forming fabric 22 moves. The cover of the vacuum box 70 is formed with a pair of slots 74 (Figures 3 and 5) corresponding to the location of the slot 68 in the full cover 66. The pressurized fluid drains the wet tissue 24 as the pressurized fluid is pulled from the air plenum .. in and through the vacuum box 62.

The fluid pressure within the air plenum 63 is desirably maintained at about 0.35 bar or greater and particularly within the range of from about 0.35 to about 2.07 bar, such as about 1.03 bar. The fluid pressure within the air plenum 60 is desirably monitored and controlled at a predetermined level.

The bottom surface 67 of the pin cover 66 is desirably arched gently to facilitate tissue control. The surface 67 is arched towards the vacuum box 62, which is arched about an axis placed on the vacuum box side of the fabric 24. The curvature of the bottom surface 67 allows a change in the angle of the combination of the support fabric 32, of the wet fabric 24 and? e the forming fabric 22 resulting in a net downward force that seals the vacuum box 62 against the entrance of the outside air and holds the wet fabric 24 during the process? e drain . The angle of the bend allows the loading and unloading of the air press 30 as required from time to time, based on the process conditions. The change in the necessary angle depends on the pressure difference between the pressure and the vacuum sides and is desirably around 5 degrees, and particularly within the range of 5 to 30 degrees, typically around 7.5 degrees.

The top and bottom surfaces 72 and 67 desirably have different radii of curvature. In particular, the radius of curvature of the bottom surface 67 is desirably larger than the radii of curvature of the top surface 72 such as to form lines of contact between the air plenum 60 and the vacuum box 62 at the leading and trailing edges. of tail 76 of the air press 30. With proper attention to the position of the support fabric 32 and the forming fabric 22 and the mechanisms of sandwiching and loading and unloading, the radii? and curvature of these surfaces can be reversed.

The front and tail edges of the air press 30 can also be provided with the end seals "8 (FIG. 3) which are kept in close proximity to or in contact with the support fabric 32 at all times. end 78 minimizes the escape of pressurized fluid between air plenum 60 and vacuum box 62 in the machine direction Suitable end seals 78 may be formed of elastic plastic compounds or the like.

With further reference to Figures 4 and 5, the air press 30 is desirably provided with the side seal members 80 to prevent the loss of pressurized fluid along the side edges 82 of the air press. The side seal members 80 comprise a semi-rigid material that is adapted to deform or flex slightly when exposed to the pressurized fluid of the air plenum 60. The illustrated side seal members 80 define a slot 84 for attachment to the housing cover vacuum 70 using a gripper bar 85 and a fastener 86 or other suitable means. In the cross sectionEach side seal member 80 is L-shaped with a leg 88 projecting upwardly from the vacuum case cover 70 into a side seal groove 89 formed in the plenum cover 66. The pressurized fluid The air plenum 60 causes the legs 88 to bend outwardly into a sealing contact with the outer surface of the side seal groove 89 of the plenum cover 66 as shown in Figures 4 and 5. Alternatively, the position? The side seal members 80 can be reversed, so that they are fixedly fastened to the full cover 66 and make a sealing contact with the contact surfaces defined by the vacuum case cover 70 (not shown). In any such alternate designs, it is desirable that the side seal member be pressed to make contact with the sealing contact surface by the pressurized fluid.

A position control mechanism 90 keeps the air plenum 60 in close proximity to the vacuum box 62 and in contact with the support fabric 32. The control mechanism e position 90 comprises a pair of levers 92 connected by the parts crossed 93 and fixedly fixed to the air plenum £ 3 through suitable fasteners 94 (figure 3). The ends of the levers 92 opposite the air plenum 60 are mounted, rotatably on the shaft 96. The position control mechanism 90 also comprises a counterbalance cylinder 93 operably connected to a fixed structural support 99 and one of the cross pieces. 93. The counterbalance cylinder 98 is adapted to extend or retract and can thus cause the levers 92 to rotate about the axis 96, which causes the air plenum 60 to move closer or away from the box. 62 In use, a control system causes the counterbalance cylinder 98 to extend sufficiently for the end seals to make contact with the support fabric 32 and for the side seal members 80 to be placed within the side seal grooves 89. The air press 30 is activated so that the pressurized fluid fills the air plenum 60 and the semi-rigid side seal members 80 are forced into a seal contact with the plenum cover 66. The pressurized fluid also creates a force upwardly tending to move the air plenum 60 outwardly of the supporting fabric 32. The control system directs the operation of the counterbalance cylinder 98 to decenter this force up based on continuous measurements of the fluid pressure within the plenum. of air 60 through the pressure monitoring system. The end seals 78 are therefore kept er. a very close proximity or in contact with the support fabric 32 at all times. The control system counterattacks or opposes random drops or peaks within the air plenum 60 by proportionally decreasing or increasing the force applied by the counterbalance cylinder 98. Consequently, the end seals 78 do not grip the fabrics. 32 and 22, which would otherwise lead to excessive wear of the fabrics.

An alternating sealing system for the air press 30 is shown representatively in Figure 6. The air plenum 100 is provided with a pivotable arm 102 defining or carrying a sealing rod 104 that is adapted to go on the supporting fabric 32. through the width of the wet fabric 24 to minimize the escape of the pressurized fluid in the machine direction. Although only one arm 102 is illustrated in Figure 6, it should be understood that a second arm at the opposite end of the air plenum 100 may be employed and constructed in a similar manner. The sides of the air plenum 100 may incorporate the side seal members 80 as described in relation to FIGS. 2 and 5 or be fixedly mounted on the vacuum box 62 to eliminate or minimize side runoff of the pressurized fluid.

The pivotable arm 102 desirably comprises a rigid material such as structural steel, graphite compounds or the like. The arm 102 has a first part 106 positioned at least partially inside the air plenum 100 and a second part 108 preferably positioned outside of the air plenum. The arm 102 is pivotally mounted on the air plenum 100 by a hinge or hinge 110. A hinge or hinge seal 112 impervious to pressurized fluid is attached to both the inner surface of a wall 114 of the air plenum 100 and to the first part. 106 to prevent the escape of pressurized fluid. The sealing rod 104 is a separate element desirably mounted on the first part 106 and motivated towards the supporting fabric 32 (not shown in Figure 6) by the contact of the pressurized fluid on the first part. Suitable sealing rods 104 can be formed of a durable material, a coefficient of friction and low strength such as ceramic, heat resistant polymers or similars.

A counterbalance bladder 120 having an inflatable chamber 122 is mounted on the second part 108 of the arm 102 with the clamps 124 or other suitable means. The chamber 122 is operably connected to a source of pressurized fluid such as air to inflate the chamber. The arm 102 and the bladder 120 are positioned so that the bladder when inflated (not shown) is pressed against the outer surface of the wall 114 of the air plenum 100 causing the arm to pivot about the hinge 110. Alternatively, a mechanism using pressurized cylinders (not shown) can be employed in place of a counterbalance bladder as means for pivoting the arm 102.

A control system is operable to inflate or deflate the bladder 120 proportionally in response to the fluid pressure within the air plenum 100. For example, as the pressure within the air plenum 100 is increased, the control system is adapted to increase the pressure within or the inflation of the counterbalance bladder 120 so that the sealing rod 104 does not grip excessively down against the support fabric 32.

The design of the vacuum transfer shoe 37 used in the transfer cloth section of the process (Figure 1) is shown more clearly in Figures 7 and 8. The vacuum transfer shoe 37 defines a vacuum slot 130 (Figure 7) connected to a vacuum source and having an "L" length which is suitably from about 0.5 to about 1 inch (12.7-25.4 millimeters). To produce a non-creped continuous dried bath tissue, a suitable vacuum slot length is about 25.4 millimeters. The vacuum slot 130 has a leading edge 132 and a tail edge 133, correspondingly forming the inward and outwardly sloping areas 134 and 135 of the vacuum transfer shoe 37. The tail edge 133 of the vacuum slot 130 is lowered relative to the leading edge 132, which is caused by the different orientation of the outgoing plain area 135 relative to that of the inbound plain area 134. The angle "A" between the planes of the inbound plain area 134 and the area outgoing plain 135 may be between about 0.5 degrees or greater, more specifically about 1 degree or greater, and even more specifically about 5 degree or greater in order to provide a sufficient separation of the forming fabric 22 and the transfer fabric 36 being these convergent and divergent.

Figure 8 further illustrates the wet tissue tissue 24 moving in the direction shown by the arrows to the vacuum transfer shoe 37. Also approaching the vacuum transfer shoe 37 is the transfer fabric 36 moving at a slower speed . The angle of convergence between the two incoming fabrics is designated "C". The angle of divergence between the two fabrics is designated "D". As shown, the two fabrics converge and diverge simultaneously at the point "P", which corresponds to the leading edge 132 of the vacuum slot 130. It is not necessary or desirable that the fabric be in contact with both fabrics over the full length of the vacuum slot 130 to effect the transfer from the forming fabric 122 to the transfer fabric 36. As is evident from Figure 8, neither the forming fabric 22 nor the transfer fabric 36 require deflection of more than a small amount to carry out the transfer, which can reduce fabric wear. Numerically, the change in direction of any fabric can be less than 5 degrees.

As mentioned previously, the transfer fabric 36 is moving at a slower speed than that of the forming fabric 22. If more than one transfer fabric is used, the speed difference between the fabrics may be the same or different. Multiple transfer fabrics can provide operational flexibility as well as a wide variety of fabric / speed combinations to influence the properties of the final product.

The level of vacuum used for differential speed transfers can be from about 3 to about 15 inches of mercury, preferably about 5 inches of mercury. The vacuum shoe (negative pressure) can be supplemented or replaced by the use of a positive pressure from the opposite side of the fabric 24 to blow the fabric over the next fabric in addition to or as a replacement to suck it onto the next fabric with vacuum. Also, roller or vacuum rollers can be used to replace the vacuum shoe.

Examples The following EXAMPLES are provided to give a more detailed understanding of the invention. The particular amounts, proportions, compositions and parameters are intended to be exemplary and are not intended to specifically limit the scope of the invention.

As referred to in the examples, the tensile strength MD, the stretch MD, and the tensile strength CD are obtained according to the test method TAPPI 494 OM-88"Paper Tension Breakdown Properties and Cardboard "using the following parameters: Speed? E crosshead 254 millimeters / minute; Full scale load is 4,540 grams; Jaw Extension (the distance between the jaws, sometimes referred to as the calibration length) is 50.8 millimeters; and the specimen width is 76.2 millimeters. The machine that tests the tension is a Sintech, Model CITS-2000 of Systems Integration Technology, Inc., of Stoughton, Massachusetts, a division of MTS Systems Corporation, of Research Triangle Park, North Carolina.

The stiffness of the example sheets can be represented ob ectively by either the maximum inclination of the machine direction (MD) load / elongation curve for the tissue (hereinafter referred to as the "MD tilt") or by the rigidity in the direction of the machine (from here on defined) that also takes into consideration the size of the tissue and the number of layers of the product. The determination of the inclination MD will be made hereafter and will be described in relation to figure 9. The inclination MD is the maximum inclination of the elongation / load curve in the direction of the machine for the tissue. The units for the MD tilt are kilograms by 3 inches (7.62 centimeters).

The MD stiffness is calculated by multiplying the MD inclination by the square root of the caliper quotient divided by the number of layers. The units of stiffness MD are (kilograms per 3 inches) - mieras05.

Figure 9 is a generalized elongation / load curve for the tissue sheet, illustrating the determination of the MD inclination. As shown, two points Pl and P2, the distance between which is exaggerated for purposes of illustration, is selected to lie along the curve? E elongation / load. The voltage tester is programmed (GAP) [General Application Program] version 2.5 Systems Integration Technology, Inc., of Stoughton, Massachusetts, a division of MTS Systems Corporation, of Research Triangle Park, North Carolina) so that it calculates a linear regression for the points that are sampled from Pl to P2. This calculation is made repeatedly on the curve by adjusting the points Pl and P2 in a regular manner along the curve (hereinafter described). The highest value of these calculations is the maximum inclination, and when it is carried out on the direction of the specimen machine, it will be mentioned here with the MD inclination.

The voltage tester program should be set so that 500 points such as Pl and P2 are taken over 63.5 millimeters of extension. This provides a sufficient number of points to essentially exceed any practical elongation of the specimen. With a crosshead speed of 254 mm / min, this translates to one point every 0.030 seconds. The program calculates inclinations between these points by putting the tenth point as the starting point (for example Pl), counting 30 points to the fortieth point (for example P2) and carrying out a linear regression on these 30 points. This stores the slope from this regression in a set. The program then counts up to 10 points to the twentieth point (which becomes Pl) and repeats the procedure again (counting 30 points to what would be the fiftieth point (which becomes P2), calculating that inclination and also storing it in the set). This process continues for the complete lengthening of the leaf. The maximum inclination is then chosen as the highest value of this arrangement. The units of the maximum inclination, are kilogram per width of specimen of three inches.

(Tension is, of course, dimensionless since the length of the elongation is divided by the length of the jaw extension.) This calculation is taken into consideration by the test machine program.

Examples 1-4. To illustrate the invention, a number of non-creped continuous dried tissues were produced using the method essentially as shown in Figure 1. More specifically, Examples 1-4 were all three layer single layer bath tissues in which the outer layers comprised disjointed eucalyptus fibers and the core layer comprised refined northern softwood kraft fibers. Cenebra eucalyptus fibers were pulped for 15 minutes at a consistency of 10% and drained to a consistency of 30%. The pulp was then fed to a Maule spreader. The disperser was operated at 70 ° C with a power input of 1.8 kilowatts-days per ton. After dispersion, a softening agent (Witco C6027) was added to the pulp in the amount of 7.5 kilograms per dry fiber metric ton (0.75% by weight).

Before forming, softwood fibers were pulped for 30 minutes at 3.2% consistency, while disbonded and dispersed eucalyptus fibers were diluted to 2.5% consistency. The weight of sheets in general layers was divided 35% / 30% / 35% for examples 1, 2 and 4 and 33% / 34% / 33% for example 3 between layers of dispersed eucalyptus / soft refined wood / eucalyptus scattered. The core layer was refined to levels required to achieve target strength values, while the outer layers provided softness and bulk. For an added temporary and dry moisture resistance, a reinforcing agent identified as Parez 631 NC was added to the core layer.

These examples employed a four-layer Beloit Concept III headbox. The kraft supply of soft northern refined wood was used in two central layers of the head box to produce a single central layer for the described three-layer product. The inserts generating reduced turbulence around 75 millimeters for the slice and layer dividers extending around 150 millimeters beyond the slice were employed. The net slice opening was 23 millimeters and the water flows in the four headbox layers were comparable. The consistency of the supply fed to the headbox was around 0.09% by weight.

The resulting three-ply sheet was formed on a twin-wire suction former roll, forming with forming fabrics being Appleton Mills 2164-B. The speed of the forming fabric varied between 11.8 and 12.3 meters per second.

The newly formed fabric was then dewatered at a consistency of 25-26% using a vacuum with vacuum from below the forming fabric without air press, and 32-33% with the air press being first transferred to the fabric of transfer which was moving at 9.1 meters per second (ur.a rapid transfer of 29-35%). The transfer fabric was Appleton Mills 2164-B. A vacuum shoe pulled around 6-15 inches (150-380 millimeters) of mercury vacuum that was used to transfer the fabric to the transfer fabric.

The fabric was then transferred to the continuous drying cloth by traveling at a speed of about 9.1 meters per second. The Appleton Mills T124-4 and T124-7 continuous drying fabrics were used. The fabric was carried on a continuous Honeycomb dryer operating at a temperature of about 175 ° C and dried to a final dryness of about 94-98% consistency.

The production sequence of the example sheets was as follows: four rolls of the sheets of Example 1 were produced. The consistency data reported in Table 1 are based on two measurements, one at the beginning and one at the end of the four rolls . The other data shown in Table 1 represent an average based on four measurements, one per roll. The air press was then turned on. The data just before and just after the activation of the air press are shown in Table 3 (individual data points). These data show that the air press caused a significant increase in voltage values. The process was then modified to lower the stress values to levels comparable to the sheets of Example 1. After this process adjustment period, four rolls of the sheets of Example 2 (this invention) were produced. Then, four rolls of the sheets of Example 3 (this invention) were produced using a different continuous drying fabric and with the air press activated. The air press was turned off and the process adjusted to regain the tensile strength values comparable to those of the sheets of Example 3. Four rolls of sheets from Example 4 were then produced. The consistency data for each example in Table 2 they are an average based on two measurements, one at the beginning and one at the end of each set of four rolls. The other data in Table 2 are based on an average of four measurements eg sheet, one per roll. In Table 2, the data from Example p 4 are presented in the left column and the data from Example 3 are presented in the right column to remain consistent with Tables 1 and 3 which show the data without the air press in the column left and the data with the air press in the right column.

Tables 1-3 give more detailed descriptions of the condition of the process as well as the resulting tissue properties for Examples 1-4. As used in Tables 1-3 below, the column headers have the following meanings: "Rapid Transfer Consistency @" is the consistency of the fabric at the point of transfer from the forming fabric to the transfer fabric, expressed as percent of solids; "MD tension" is the resistance to stress > n in the direction of the machine, expressed in grams per 7.62 centimeters of sample width; "CD tension" is the resistance to the transverse tension to the machine, expressed as grams per 7.62 centimeters of sample width; "MD stretch" is the stretch in the machine direction, expresac: as the percent elongation to sample failure- "MD incline" is defined above, expressed as kilograms per 7.62 centimeters per sample width; "Caliber" is the caliber? A sheet measured by a Bulk Micrometer (TMI Model 49-72-OC Amityv lle, New York) having an anvil diameter of 103.2 millimeters) and an anvil pressure of 220 grams / f? square (3.39 kilopascals) expressed in microns; "MD stiffness" is the stiffness factor in the machine direction as defined above, expressed in (kilograms per 3 inches) -mieras05; the "Base Weight" is the finished basis weight, expressed as grams per square meter; "TAD fabric" means dried cloth continuously; "Refiner" is the power input to refine the central layer, expressed as kilowatts; "Speed" is the difference in speed between the forming fabric and the fabric, and the slower transfer, divided by the speed of the cloth, is transferred and expressed as a percentage; "HW / SW" is the breaking of the weight of the fibers of hardwood (HW) and softwood (SW) in the tissues of single stratum of three layers, expressed as a percentage of the weight of total fiber; and "Parez" is the aggregate rate of Parez 631 NC expressed as kilograms per metric ton of core layer fiber.

Table 1 EXAMPLE 1 EXAMPLE 2 (Without press (With air press) air and adjustment process) Fast Transfer Consistency® (%) 25.2-26.1 32 .5-33.4 MD Tension (grams / 3 Inches) 933 944 CD Tension (grams / 3 Inches) 676 662 MD Stretch (%) 24.5 24.7 MD Inclination (Kg / 3 Inches) 4,994 3,778 Caliber (microns) 671 607 MD Stiffness (Kg / 3 Inch -Mieras05 129 93 Base Weight (gsm) 34.6 35.2 Fabric TAD T-124-4 T - 124-4 Refiner (kW) 32 26 Rushed (%) 32 29 HW / SW (%) 70/30 70/30 Parez (kg / mt) 4.0 3.2 Table 2 EXAMPLE 4 EXAMPLE 3 (Without press (With air press) air and adjustment process) Fast Transfer Consciousness® (%) 24.6 32.4 MD (grams / 3 Inches) Voltage 961 907 CD Voltage (grams / 3 Inches) 714 685 MD Stretch (%) 23.5 24.4 MD Inclination (Kg / 3 Inches) 5,668 3,942 Caliber (microns) ) 716 704 Rigidity MD (Kg / 3 In. -Mieras0 5 152 105 Base Weight (gsm) 35.0 35.1 Fabric TAD T-124-7 T-124-7 Refiner (kW) 40 34.5 Rushed. { %) 35 31 HW / SW (%) 66/34 70/30 Parez kg / mt) 2.5 2.5 Table 3 Without press (With air press) air) Fast Transfer Conscious® (%) 25.2 32.5 MD Tension (grams / 3 Inches) 915 1099 DC Tension (grams / 3 Inches) 661 799 DC wet tension 127 150 MD stretch (%) 24.4 28.5 MD Inclination (Kg / 3 Inches ) 4,996 4,028 Caliber (micras) 665 630 Rigidity MD (Kg / 3 In. -Mieras05 129 101 Base Weight (gsm) 34.3 34.6 Fabric TAD T-124-4 T-124-4 Refiner (kW) 32 32 Rushed (%) 32 32 HW / SW (%) 70/30 70/30 Parez (kg / mt) 4.0 4.0 As shown by the previous examples, the air press produced significantly higher consistencies upstream of the differential speed transfer that resulted, in smoother sheets as evidenced by the lower module values. Desirably, the modulus (MD stiffness) of the tissue products is at least 20% less than that of a comparable tissue product made without an additional drain at a consistency of more than about 30%. further, the tension in the machine direction of the tissue products is at least 20% greater, and the tension in the transverse direction of the tissue products is at least 20% greater than that of ur. comparable tissue product made without a complementary drain at a consistency of more than about 30%. Additionally, the stretch in the machine direction of the tissue products is at least 17% greater than that of a comparable tissue product made without a complementary drainage at a consistency of more than about 30%. .

The above detailed description has been given for illustration purposes. Therefore, a number of modifications and changes can be made without departing from the spirit and scope of the present invention. For example, alternate or optional features described as part of one modality may be used to give another modality. Additionally, the two named components can represent parts of the same structure. In addition, various processes and equipment arrangements as described in the publication of patent application PCTWO95 / 00706 dated January 5, 1995 and in the United States patent? E North America application serial No. 08 / 330,166 filed on 27 October 1994 by Engel et al. and entitled "Method for Making Continuously Dry, Non-Creped Sheets" whose descriptions are incorporated herein by reference may be employed. Therefore, the invention should not be limited by the specific embodiments described but only by the claims.

Claims (27)

1. A method for making a soft tissue sheet comprising the steps of: depositing an aqueous suspension of fibers to make paper on an endless forming fabric to form a wet fabric; dewatering the wet tissue to a consistency of from about 20 to about 30 percent; further draining the wet fabric using non-sympathetic dewatering media at a consistency of more than about 30 percent; transferring the dewatered fabric in addition to a transfer fabric traveling at a speed? e from about 10 to about 80 percent slower than that of the forming fabric; transfer the fabric to a continuous dg cloth; Dry the fabric continuously to a final dryness.

2. The method as claimed in clause 1 characterized in that the r.o comprehensive drainage means are selected from the group consisting of air press, infrared dg, microwave dg, sonic dg, continuous dg, and dewatering with displacement.

3. The method as claimed in clause 1 characterized in that the non-comprehensive drainage means comprise an air press.

4. The method as claimed in Clause 3 characterized in that the air press increases the consistency of the wet fabric by at least about 3 percent.

5. The method as claimed in clause 3 characterized in that the air press comprises an air plenum and a fluid pressure within the air plenum is maintained within the range of about 5 to about 30 pounds per square inch.

6. The method as claimed in clause 3, 4 or 5, characterized in that the air press provides a pressure difference across the wet fabric from about 35 to about 60 inches of mercury.

7. The method as claimed in clause 3, 4 or 5, characterized in that the air press drains the wet tissue to a consistency of more than about 31 percent.

8. The method as claimed in clause 7 characterized in that the air press drains the wet tissue to a consistency of more than about 32 percent.

9. The method as claimed in clauses 3, 4 or 5 characterized in that the air press drains the wet fabric to a consistency of from about 31 to about 36 percent.

10. The method as claimed in 1 characterized in that the drainage of the wet fabric to a consistency of from about 20 to about 30 percent is achieved using a plurality of vacuum boxes.

11. The method as claimed in clause 3, characterized in that the wet fabric is placed in the form of a sandwich between the forming fabric and a support fabric when it is transported through the air press.

12. The method as claimed in clauses 1, 3 or 4 characterized in that the forming fabric moves at a speed of at least about 2003 feet per minute.

13. The tissue product made by the method as claimed in clause 1.

14. The tissue product as claimed in clause 13 characterized in that the modulus of the tissue product is at least about 20 percent smaller than that of the comparable tissue product made by the method as claimed in clause 1 except for the complementary drain to a consistency of more than about 30 percent.

15. The tissue product as claimed in clause 13 characterized in that the tension in the machine direction of the tissue product is at least about 20 percent greater than that of the comparable tissue product made by the method of clause 1 except without a drain complementary to a consistency of more than around? e 30 percent.

16. The tissue product as claimed in clause 13, characterized in that the tension in the transverse direction of the tissue product is at least about 20 percent greater than that of a comparable tissue product made by the method of the invention. clause 1 except without ur. drain complementary to a consistency of more than around? e 30 percent.

17. The tissue product as claimed in clause 13, characterized in that the stretching in the machine direction of the tissue product is at least about 17 percent greater than that of the comparable tissue product made by the method as claimed in clause 1 except without the complementary drain to a consistency of around 30 percent.

18. An air press for draining a wet fabric comprising: an air plenum comprising a full roof that has a bottom surface; means for supplying a pressurized fluid to the plenum; a vacuum box comprising a cover? e vacuum box having a top surface positioned er. close proximity to the bottom surface of the roof; means for applying vacuum to the vacuum box; Y side seal members adapted to make contact with the plenum and the vacuum box to minimize the escape of the pressurized fluid, the side seal members attached to one of the plenum and the vacuum box and placed in close proximity to the lateral contact surfaces and side seal defined by the other of the air plenum and the vacuum box, the side seal members are adapted to flex in a sealing contact with the lateral seal contact surface with exposure to the pressurized fluid.

19. The air press as claimed in clause 18 characterized in that the side seal members are attached to the vacuum case cover and the plenum cover defines the side seal grooves and the side seal contact surfaces.

20. The air press as claimed in clause 18 further characterized in that it comprises the end seals attached to the plenum cover.

21. The air press as claimed er. clauses 18 or 20 characterized in that it also comprises a position control mechanism adapted to maintain the plenum of air in close proximity to the vacuum box.

22. The air press as claimed in clause 21 characterized in that the position control mechanism comprises a lever mounted rotatably attached to the air plenum and a counterbalance cylinder adapted to rotate the lever.

23. The air press as claimed in clause 21, characterized in that it comprises a control system adapted to direct the operation of the counterbalance cylinder in response to measurements of the fluid pressure within the air plenum.

24. The air press as claimed in clauses 18, 19 or 20, characterized in that the upper and bottom surfaces are arched towards the vacuum box.

25. The air press as claimed in clause 24 characterized in that the upper and bottom surfaces have different radii of curvature.

26. An air press for draining a wet fabric, comprising: an air plenum comprising a full cover having a bottom surface; means for supplying pressurized fluid to the plenum; a vacuum box comprising a vacuum box cover having a top surface positioned in close proximity to the bottom surface of the plenum cover; means for applying vacuum to the vacuum box; an arm mounted in the form of a pivot on the air plenum and comprising the first and second parts, the first part located at least partially within the air plenum and comprising a sealing rod; Y means for pivoting the arm in response to fluid pressure within the plenum.

27. The air press as claimed in clause 26 further characterized in that it comprises a hinge seal impervious to pressurized fluid and attached to both the air plenum and the first part. SUMMARY A non-creped tissue sheet having an improved smoothness results from the supplemental draining of a wet fabric to a consistency of more than about 30 percent using non-compressive drainage techniques prior to a transfer and differential velocity and subsequent continuous drying. A particularly suitable air press for providing complementary non-compressive drainage incorporates side and / or end seals to minimize the escape of pressurized fluid.