RU2419546C2 - Fabric-creped absorption sheet with variable local basic weight - Google Patents

Abstract

FIELD: textile, paper. ^ SUBSTANCE: absorbing cellulose sheet has a variable local basic weight and contains a paper-fibre mesh made of multiple extended compact areas and multiple fibre-rich top areas. At the same time the extended compact areas are made of pressed paper fibres. Besides, the pressed fibres are aligned in general in a machine direction of the sheet and have a relatively low local basic weight, and also front and back edges at their longitudinal ends. And enriched fibres of top areas are connected to multiple extended compact areas. Besides, the top areas have relatively high local basic weight and multiple collars passing across the machine direction of the collars, having vault-like profiles relative to the front and rear edges of multiple extended compact areas. Invention also relates to a method to make such a sheet. ^ EFFECT: group of inventions ensures production of an absorbing sheet, having improved qualities, such as volume, softness and rupture strength, using repeatedly used fibres as a material. ^ 16 cl, 46 dwg, 14 tbl

Description

FIELD OF THE INVENTION

This application relates generally to absorbent sheets for paper towels and tissue paper. Conventional products have a variable local base weight with (i) elongated densified areas oriented along the machine direction of the product, having a relatively low base weight, and (ii) fiber-enriched regions with a relatively high base weight between the densified areas.

State of the art

Methods of making tissue paper, towels, and the like are well known, including various features such as drying with a Yankee cylinder (American tumble dryer), through drying, fabric creping, dry creping, wet creping and so on. Conventional wet pressing (CWP) processes have certain advantages over conventional through air drying (TAD) processes, including: (1) lower energy costs associated with mechanical removal of water compared to evaporative drying with hot air; and (2) higher production rates, which are more easily achieved by processes that use wet pressing to form the web. On the other hand, air-through drying processes have become the method of choice for a new capital investment, in particular for the production of soft, voluminous, high-quality towels.

Tissue creping is used in conjunction with papermaking processes that include mechanical or compressive dewatering of the paper web as a means of influencing product properties. See U.S. Patent Nos. 4,689,119 and 4,551,199 to Weldon ; 4,849,054 to Klowak ; and 6287426, Edwards et al . The implementation of tissue creping processes is hindered by the difficulty of efficiently transferring a web with a high or intermediate consistency to a desiccant. Additional patents relating to tissue creping include the following: 4834838; 4,482,429; and 4,445,638. Note also US Pat. No. 6,350,349 to Hermans et al. , which describes the wet transfer of the web from a rotating transfer surface to the fabric.

As for paper manufacturing processes, fabric molding is also used as a means of providing texture and volume. In this regard, in US patent No. 6610173, Lindsey et al. , describes a method of printing a paper web during wet pressing, which leads to asymmetric protrusions corresponding to the deflecting grooves of the deflecting element. The '173 patent teaches that the difference in transfer speed during pressing serves to improve the forming and printing of the web by the deflecting element. It is reported that the resulting fabric fabric has a special set of physical and geometric properties, such as a patterned compacted mesh and a repeating pattern of protrusions having asymmetric structures. For wet forming webs using textured fabrics, see also the following US patents: 6017417 and 5672248, both Wendtl et al. ; 5508818, Hermans et al. and 4637859, Trokhan . For the use of fabrics used to impart texture, mainly to dry sheets, see US Patent No. 6,585,855 to Drew et al. And also US Publication No. US 2003/0000664.

U.S. Patent No. 5,507,715, Trokhan et al. describes a cellulosic fibrous structure having many regions separated from each other by another base weight. This structure is reported to have a substantially continuous net of high base weight and separate regions of low base weight that surround individual regions of the intermediate base weight. Cellulose fibers forming areas of low base weight can be radially oriented relative to the centers of these areas. This paper can be molded by using a forming belt having zones with different hydraulic resistance. The base weight of a certain region of paper is usually inversely proportional to the hydraulic resistance of the zone of the forming belt on which this region is molded. Zones with different hydraulic resistance provide selective runoff of a liquid carrier containing suspended cellulose fibers through different zones of the forming belt. A similar structure is described in US patent No. 5935381, also Trokhan et al., Where these signs are achieved by using different types of fibers.

Dried through drying (SHS), creped products are described in the following patents: US patent No. 3999477, Morgan, Jr. et al .; U.S. Patent No. 4,102,737 to Morton ; and U.S. Patent No. 4,529,480 to Trokhan . The processes described in these patents include, in general, forming the web on a perforated carrier, thermal pre-drying the web, transferring the web to the Yankee cylinder with a clamp, determined in part by the fabric, and creping the product from the Yankee cylinder. Typically, a web with relatively uniform permeability is required, which makes it difficult to use reusable raw materials at a level that may be desirable. The transfer to the Yankee cylinder usually takes place at a web consistency of from about 60% to about 70%.

As noted above, through-dried products tend to exhibit increased volume and softness; however, thermal dehydration with hot air tends to be energy intensive and requires a substrate with relatively uniform permeability. Thus, wet pressing operations where the web is mechanically dehydrated are energy-efficient and easier to apply to raw materials containing recycled fiber, which tend to produce a web with less uniform permeability than the original fiber. A Yankee cylinder can be used more efficiently, since the fabric is transferred onto it with a consistency of 30% or those that allow the fabric to adhere securely for drying.

Despite many improvements in the art, improvements in the quality of the absorbent sheet, such as volume, softness, and tensile strength, are usually associated with a compromise with respect to one property in order to benefit from another. In addition, existing high-quality products usually use limited amounts of recycled fiber or do not use it at all, despite the fact that the use of recycled fiber is environmentally friendly and much less expensive than the original kraft fiber.

SUMMARY OF THE INVENTION

The present invention provides absorbent paper sheet products with a variable local base weight, which can be made by dewatering the raw materials by compaction and wet creping the resulting web in a fabric selected in such a way that an absorbent sheet with a multitude of elongated, machine-oriented, densified areas with relatively low base weight and many fiber-enriched areas with relatively high local base weight, which occupy a large area ISTA.

These products are prepared in various forms suitable for tissue paper or paper towels, and have remarkable absorbency over a wide range of base weights, demonstrating, for example, Porofil® porosity above 7 g / g even at high base weights. As for tissue paper, the sheet of the present invention has surprising softness with high strength, offering a combination of properties that is particularly desirable in the industry. As for paper towels, the absorbent sheet of the present invention allows the use of large amounts of reusable fiber without compromising softness and absorbency; again, there is a significant advantage over the current level of technology.

In another aspect of the invention, the efficiency of the paper machine is increased by feeding a sheet to the Yankee cylinder, which exhibits greater thickness increment / reeling crepe ratios that cause less speed limits on the mesh part — a manufacturing bottleneck for many paper machines.

The invention is easier to understand by reference to FIGS. 1 and 2. FIG. 1 is a micrograph of an absorbent sheet 10 of the present invention, and FIG. 2 is a sectional view showing a structure of a sheet along a machine direction. 1 and 2, it can be seen, in particular, that the sheet 10 according to the invention includes a plurality of relatively high local local base weights extending across the machine direction (CD) of fiber-rich, cap or comb regions 12 connected by a plurality of elongate densified regions 14 having relatively low local base weight, which are generally oriented along the machine direction (MD) of the sheet. The elongated densified regions extend in MD to a length of 18, and they extend in CD to a length of 20. The elongated densified regions differ in the MD / CD ratio, i.e. a distance of 18 divided by a distance of at least 1.5. The density profile and the change in base weight can be further estimated by reference to FIG. 2, which is an enlarged micrograph of a section of a sheet taken along line X-S # 1 of FIG. 1. Figure 2 also shows that the cap regions 12 include a high concentration of fiber having a fiber orientation offset across the machine direction (CD), as confirmed by the cut fiber ends seen in the photograph. This shift in fiber orientation is further seen in the high CD tensile and tensile strengths discussed below. Figure 2 further shows that the elongated densified regions 14 include a highly compressed fiber 16, which also has a displacement of the fiber in the transverse direction, as confirmed by the cut ends of the fiber.

The fiber orientation shift is also illustrated in FIG. 1, where it is seen that the fiber-enriched cap regions 12 are limited at the lateral edges by CD oriented, elongate densified regions 14 and that the regions 12 generally extend in the CD direction between the aligned densified regions, being associated with them CD spreading fibers. See also FIGS. 16-18.

One of the notable features of this invention is the increased absorbency, as confirmed by FIG. 3, for example, which shows that the absorbent sheet of the invention exhibits very high porosity even at high paper weights. Figure 3 shows that products having a Porofil® porosity of 7 grams / gram or more are readily prepared according to the present invention at a paper density of 12 f / stop (19.5 g / m ² ) and a paper density of 24 f / stop ( 39.1 g / m ² ) and more. This wide range of absorbency is remarkable, especially for compressive dehydrated, wet creped products (prior art wet creped products typically have a porosity of less than 5 grams / gram).

Additional details and features of the proposed products and the method of their manufacture are discussed below.

Brief Description of the Drawings

The invention is described in detail below with reference to various figures, where like numbers refer to like parts. In the figures:

Figure 1 is a top view of an absorbent cellulosic sheet of the present invention;

Figure 2 is an enlarged micrograph of a section along the line X-S # 1 of figure 1, showing the microstructure of the proposed sheet;

Figure 3 is a graph showing Porofil® porosity in gram / gram of various products, including products of the present invention;

Figure 4 is a schematic view showing tissue creping performed according to the present invention;

5 is a schematic diagram of a paper machine that can be used to make products of the present invention;

6 is a schematic view of another paper machine that can be used to make products of the present invention;

7 is a halftone topographic micrograph of a multilayer fabric that is used as a creping fabric for the manufacture of the products of the present invention;

Fig. 8 is a color topographic representation of the creping fabric shown in Fig. 7;

Fig. 9 is a schematic view illustrating a creping fabric clip using the fabric of Figs. 7 and 8;

Figure 10 is an enlarged schematic view of a part of the creping clip shown in figure 9;

11 is another enlarged schematic view of a creping clamp in figures 9 and 10;

Fig is another another enlarged schematic view of a creping clip in Fig.9, 10 and 11;

Fig.13 is a schematic representation of the pattern of the creping fabric of Figures 7 and 8, as well as a schematic representation of a patterned product made using this fabric;

FIG. 14 is a schematic representation of the creping fabric pattern of FIGS. 7 and 8 aligned with a sheet obtained using this fabric, where it is seen that the MD fists correspond to the densified areas in the fabric;

Fig. 15 is a micrograph similar to Fig. 2, showing the structure of the cap regions of the sheet after the sheet has been pulled out in a machine direction;

Fig.16 is a photograph of an absorbent cellulosic sheet of the present invention, similar to Fig.1;

Fig.17 is a photomicrograph of a section taken along the line X-S # 2 shown in Fig.16, where it is seen that the fiber-enriched cap areas of the sheet were not fist-tightened;

Fig. 18 is an enlarged view showing an impression of an MD fist on a sheet of the present invention;

Fig is an x-ray negative through the sheet of the present invention with a long exposure, 6 kV;

Fig. 20 is another x-ray negative through a sheet of the present invention with continuous exposure, 6 kV;

21A-21D are micrographs of various sheets of the present invention at different thicknesses and the same creping ratios;

Fig. 22 and Fig. 23 are micrographs showing a cross section of an absorbent sheet of the present invention along a machine direction;

24 is a sectional view of an absorbent sheet obtained by the CWP process;

25 is a calibration curve for attenuating beta particles of a paper density profiler;

FIG. 26 is a schematic diagram showing locations of local paper density measurements on a sheet of the present invention; FIG.

Fig. 27 is a histogram comparing, in a pairwise comparison, the softness of a sheet creped with a fabric of the class shown in Figs. 7 and 8 with the softness of an absorbent sheet creped with a single layer fabric;

FIG. 28 is a graph of a pairwise comparison of softness with respect to elongation of a creped sheet of the class shown in FIGS. 7 and 8 and an absorbent sheet creped with a single layer fabric; FIG.

FIG. 29 is a graph of suction thickness for an absorbent sheet made with a single layer fabric and an absorbent sheet made with a multilayer fabric of the class shown in FIGS. 7 and 8;

30A-30F are micrographs of fabric creped sheets;

Fig is a histogram illustrating a pairwise comparison of the softness of various products of the present invention;

32 is a schematic diagram of yet another paper machine useful for practicing the present invention;

Fig. 33 is a graph of thickness of CD of wet tensile strength for various fabric creped sheets;

Fig. 34 is a graph of CD stiffness of wet tensile strength for various fabric creped sheets which are particularly suitable for automatic proximity valves;

Fig. 35 is a graph of the thickness of a base sheet from fabric creping; and

Figures 36-38 are micrographs showing the effect of combined reeling creping and fabric creping on an absorbent sheet.

With regard to microphotographs, the magnifications indicated here are approximate unless a portion of a scanning electron micrograph is shown where the absolute scale is shown.

Detailed description

The invention is described below with reference to numerous embodiments. This discussion is for illustrative purposes only. Modifications of specific examples within the spirit and scope of the present invention set forth in the claims will be readily apparent to those skilled in the art.

In a first aspect of the present invention, there is provided an absorbent cellulosic sheet having a variable local base weight, comprising a paper fiber web containing (i) a plurality of fiber-rich, cross-sectioned, bonded areas with a relatively high local base weight, connected by ( ii) a plurality of elongated densified regions of the compressed paper fibers, the elongated densified regions having a relatively low local base weight and generally vans along the machine direction (MD) of the sheet. The elongated densified areas are further characterized by an MD / CD ratio of at least 1.5. This sheet has a specific volume of more than 5.5 ((mils / 8 layers) / (f / stop)) (more than 0,085 (mm / 8 layers / g / m ²⁾⁾ and has a porosity of 9 grams / gram or greater, when it has a base weight of 23 lb / stop (37.5 g / m ² ) or less, or has a porosity of 7 grams / g or more, when it has a base weight of more than 23 lb / stop (37.5 g / m ² ) Typically, the MD / CD ratio of the densified regions is greater than 5 or greater than 6; typically from about 6 to 10. In most cases, the fiber-enriched bonnet regions have a fiber orientation shift in the CD sheet direction, and the densified areas with a relatively low local base weight extend in the machine direction and also have a fiber orientation shift along the CD sheet.

In one preferred embodiment, the fiber-enriched cap regions are limited at the lateral edges of a side-mounted pair of CD-aligned densified regions; and these fiber-enriched regions are at least partially limited at their intermediate lateral edges at the longitudinal parts of a longitudinally arranged, CD-staggered pair of densified regions. For many sheet products, this sheet has a base weight of 8 pounds per 3000 square foot (13 g / m ² ) to 35 pounds per 3000 square foot (57.0 g / m ² ) and porosity of 7 gram / gram or more. The sheet may have a porosity equal to or greater than 7 grams / gram and possibly up to 15 grams / gram. Suitable porosity equal to or greater than 8 grams / gram and up to 12 grams / gram is visible in FIG.

The present invention provides products with relatively high Porofil® porosity even with a high base weight. For example, in some cases, the sheet has a base weight of 20 pounds per 3000 square foot (32.5 g / m ² ) to 35 pounds per 3000 square foot (57.0 g / m ² ) and a porosity of 7 grams / grams or more and up to 15 grams / gram is possible. Suitably, the porosity is equal to or greater than 8 or 9 grams / gram and up to 12 grams / gram.

Prominent features of the invention also include high CD elongation and the ability to use reusable raw materials in high quality products. Typical is a CD elongation of 5% to 10%. At least 5%, at least 7%, or at least 8% are preferred in some cases. Paper fiber may have 50% by weight of fiber recycled fiber or more. At least 10%, 25%, 35% or 45% is used depending on the availability and suitability for this product.

Another aspect of the present invention is directed to a tissue paper backing sheet showing softness, increased volume and high strength. Thus, the absorbent sheet according to the invention may be in the form of a tissue paper backing sheet, where the fiber is predominantly solid wood fiber and the sheet has a volume of at least 6 ((mil / 8 layers) / (ft / foot)) (0.093 (mm / 8 layers) / (g / m ² )), or in the form of a yarn sheet, where the fiber is predominantly solid wood fiber and the sheet has a volume of at least 6.5 ((mil / 8 layers) / ( f / foot)) (at least 0.1 (mm / 8 layers) / (g / m ² )). Typically, the sheet has a volume equal to or greater than 6.6 and up to about 8 ((mil / 8 layers) / (feet / foot)) (greater than 0.1, up to about 0.125 (mm / 8 layers) / (g / m ² )), and is introduced into the two-layer product yew. The sheet according to the invention is also provided in the form of a tissue paper sheet, where the fiber is predominantly solid wood fiber, and this sheet has a normalized GM tensile strength of more than 21 ((g / 3 ") / (lbs / stop)) (more than 1 69 (g / cm) / (g / m ² )) and a volume of at least 5 ((mils / 8 layers) / (feet / foot)) (at least 0.08 (mm / 8 layers) / (g / m ² )) up to about 10 ((mils / 8 layers) / (feet / foot)) (up to about 0.15 (mm / 8 layers) / (g / m ² )). Usually a sheet of tissue paper has GM normalized tensile strength from greater than 21 ((g / 3 ") / (pounds / stop)) (large less than 1.69 (g / cm) / (g / m ² )) and up to approximately 30 ((g / 3 ") / (pounds / stop)) (or 2.42 (g / cm) / (g / m ² )).

This base sheet may have a normalized GM tensile strength of 25 ((g / 3 ") / (pounds / foot)) (2 (g / cm) / (g / m ² )) or more and is introduced into the two-ply tissue product of tissue paper.

Alternatively, the proposed products are obtained in the form of a towel base sheet containing mechanical pulp, where at least 40% by weight of the paper fiber is softwood fiber, or in the form of a towel base sheet where at least 40% by weight of the paper fiber is softwood fiber and at least 20% by weight of paper fiber is recycled fiber. At least 30%, at least 40%, or at least 50% of the paper fiber may be recycled fiber. Even 75% or 100% fiber can be recycled fiber in some cases.

A typical double-layered towel base sheet has a base weight in the range of 12 to 22 pounds per 3000 square foot and an 8-sheet thickness of more than 90 mils, up to about 120 mils (19.8 to 35.8 g / m ² and an 8-sheet thickness of more than 2.3 mm, to about 3.1 mm). The base sheet can be turned into a towel with a CD stretch of at least about 6%. Typically, CD elongation in the range of 6% to 10% is provided, sometimes CD elongation of at least 7% is preferred.

The present invention is also suitable for the manufacture of towel base sheets for use in automatic towel dispensers. Thus, this product is provided in the form of a towel base sheet, where at least 40% by weight of the paper fiber is softwood fiber and at least 20% by weight of the paper fiber is reusable fiber and where the bending length MD of the base sheet is from about 3.5 cm to about 5 cm. The bending length MD of the base sheet in the range of from about 3.75 cm to about 4.5 cm is typical.

Such sheets may include at least 30% recycled fiber, at least 40% recycled fiber. In some cases, at least 50% of the recycled fiber. Even 75% or 100% by weight of recycled fiber can be used. Typically, the substrate sheet has a volume of more than 2.5 ((mils / 8 layers) / (p / ream)) (greater than 0,039 (mm / 8 layers) / (g / m ^2)), such as a volume of from greater than 2 5 ((mils / 8 layers) / (f / stop)) (more than 0,039 (mm / 8 layers) / (g / ^m2)) to about 3 ((mils / 8 layers) / (lb / ream) ) (up to approximately 0.047 (mm / 8 layers) / (g / m ² )). In some cases, it is desirable to have a volume of at least 2.75 ((mils / 8 layers) / (ft / foot)) (at least 0.043 (mm / 8 layers) / (g / m ² )).

Another aspect of the present invention is an absorbent cellulosic sheet having a variable local base weight comprising a patterned fibrous paper web consisting of: (a) a plurality of machine oriented (MD) oriented, elongate densified areas of compressed paper fibers, having a relatively low local base weight, as well as leading and trailing edges, and these compacted areas are arranged in a repeating pattern of many generally parallel linear arrays that are olagayutsya longitudinally staggered with respect to each other so that a plurality of linear arrays located intermediate between a pair of CD-aligned densified regions; and (b) a plurality of fiber-enriched, bonnet areas having a relatively high local base weight distributed between and associated with the densified areas, the bonnet areas having ridges extending generally across the sheet machine direction; in this case, in general, parallel longitudinal arrays of densified regions are arranged and arranged so that the fiber-enriched region between a pair of CD-aligned densified regions is freely distributed in the CD using the leading and trailing edges of the densified regions of at least one intermediate linear array. Usually, generally, parallel, longitudinal arrays of densified regions are arranged and arranged such that the fiber-enriched region between a pair of CD-aligned densified regions is freely distributed in the CD by the leading and trailing edges of the densified regions of at least two intermediate linear arrays. Therefore, in general, parallel longitudinal arrays of densified regions are arranged and arranged such that the fiber-enriched region between a pair of CD-aligned densified regions is at least partially truncated in MD and at least partially limited in MD by the leading and trailing edges of the densified regions along at least one intermediate linear array of this sheet in the MD position, the intermediate MD position of the front and rear edges of the CD-aligned densified areas. More preferably, in general, parallel longitudinal arrays of densified regions are arranged and arranged such that the fiber-enriched region between the pair of CD-aligned densified regions is at least partially truncated in MD and at least partially limited in MD by the leading and trailing edges of the densified regions along at least two intermediate linear arrays of this sheet in the MD position, the intermediate MD position of the front and rear edges of the CD-aligned densified areas. From the various figures it can be seen that the front and rear MD edges of the fiber-enriched cap areas are generally concave inward, so that the central MD section of the fiber-rich areas is smaller than the MD section at the lateral edges of the fiber-rich areas. In addition, elongated densified areas occupy from about 5% to about 30% of the sheet area; more typically, elongated densified areas occupy from about 5% to about 25% of the sheet area or elongated densified areas occupy from about 7.5% to about 20% of the area of the sheet. Enriched with fiber, the cap regions typically occupy from about 95% to about 50% of the sheet area, for example, from about 90% to about 60% of the sheet area.

Although any suitable repeating pattern can be used, linear arrays of densified areas have an MD repetition rate of from about 50 meter ^-1 to about 200 meter ^-1 , for example, an MD repetition rate of from about 75 meter ^-1 to about 175 meter ^-1 or an MD repetition rate from about 90 meter ^-1 to about 150 meter ^-1 . The densified areas of linear sheet arrays have a repeat frequency of CD from about 100 meter ^-1 to about 500 meter ^-1 ; typically, a CD repetition rate of from about 150 meter ^-1 to about 300 meter ^-1 ; for example, a CD repetition rate of from about 175 meter ^-1 to about 250 meter ^-1 .

In yet another aspect of the present invention, there is provided an absorbent cellulosic sheet having a variable local base weight comprising a patterned paper fibrous web consisting of: (a) a plurality of elongated densified areas of pressed paper fibers, the densified fibers being oriented generally in the machine direction (MD) of the sheet and have a relatively low local base weight, as well as leading and trailing edges at their longitudinal ends; and (b) a plurality of fiber-rich, bonnet regions connected to a plurality of elongate densified regions, the bonnet regions having (i) a relatively high local base weight and (ii) a plurality of ridges extending across the machine direction (CD) having vaulted CD profiles relative to the front and trailing edges of a plurality of elongated densified areas.

Many embodiments of the present invention include an absorbent cellulosic sheet having a variable local base weight, comprising a paper fiber mesh consisting of: (a) a plurality of fiber-rich, cross-sectioned machine direction (CD), bonded areas with a relatively high local base weight having a fiber inclination along the CD sheet adjacent to (ii) a plurality of densified areas of compressed paper fibers, the densified areas having a relatively low local base vy weight and disposed between pileate regions.

In another aspect of the present invention, there is provided an absorbent cellulosic sheet having a variable local base weight, comprising (i) a plurality of machine direction (CD) spreading, fiber enriched areas with a relatively high local base weight, and (ii) a plurality of low base weight regions alternating with areas with a high base weight, where typical areas within areas with a relatively high base weight show a characteristic local base weight of at least 25% higher than Black local base weight of typical areas in areas with low base weight. In other cases, the characteristic local base weight of typical areas within areas with a relatively high base weight is at least 35% higher than the characteristic local base weight of typical areas in areas with a low base weight; while in still other cases, the characteristic local base weight of typical areas within areas with relatively high base weights is at least 50% higher than the characteristic local base weight of typical areas in areas with low base weights. In some embodiments, the characteristic local base weight of typical areas within areas with relatively high base weights is at least 75% higher than the characteristic local base weight of typical areas in areas with low base weights, or at least 100% higher than typical local base weight of areas with low base weight. The characteristic local base weight of typical areas within areas with relatively high base weights may be at least 150% higher than the characteristic local base weight of typical areas in areas with low base weights; in general, the characteristic local base weight of typical areas within areas with a relatively high base weight is 25% to 200% higher than the characteristic local base weight of typical areas in areas with a low base weight.

In another embodiment of the present invention, an absorbent cellulosic sheet is produced having a variable local base weight, comprising (i) a plurality of machine-spreading (CD) fiber enriched areas with a relatively high local base weight and (ii) a plurality of elongated areas with a low base weight generally oriented in the machine direction (MD), where areas with relatively high local base weights spread in the CD typically at a distance of from about 0.25 to about A total of 3 distances over which elongated regions with a relatively low base weight extend in MD. This feature is visible in FIGS. 19, 20. Typically, the fiber-enriched regions are cap regions having many macro folds. Therefore, the elongated regions with a low base weight also have an MD / CD ratio of greater than 2 or 3, usually from about 2 to 10, for example, from 2 to 6.

The present invention also includes methods for producing an absorbent sheet.

In still other aspects of the present invention, there is provided a method of manufacturing a tape-creped absorbent cellulose sheet, comprising: (a) compressing the dewatering of a pulp to form a nascent web having an obviously random distribution of paper fiber orientation; (b) applying a dehydrated web having an obviously random distribution of fiber orientation on a transfer surface moving at a first speed; (c) tape creping the web from the transfer surface at a consistency of from about 30% to about 60% using a patterned creping tape, wherein the creping step is performed under pressure in the tape creping clip defined between the transfer surface and the creping tape where the tape is moving with a second speed less than the speed of said transfer surface. The tape pattern, pressure parameters, speed difference, and web consistency are selected so that the web is creped from the transfer surface and redistributed onto the creping tape to form a web with a grid having many connecting areas with different local base weights, including at least (i) many enriched fiber, flat areas with a high local base weight, connected by (ii) a set of elongated densified areas of compressed paper fiber. Elongated densified areas have a relatively low local base weight and are generally oriented along the machine direction (MD) of the sheet. The elongated densified regions further have an MD / CD ratio of at least 1.5; and this method further includes (d) drying the web. Preferably, the creping tape is a fabric. This method may further include applying suction to the creped web while it is in the creping fabric. Most preferably, the creping tape is a woven creping fabric with protruding MD base fists that protrude into the creping clip more than weft fists of the fabric, and the creping fabric is a multi-layer fabric. Hat areas include extendable macro folds that can be expanded by stretching the web along an MD sheet. In some embodiments, the implementation of the cap regions include extendable macro folds and extendable micro folds inserted therein, and the method further includes the step of pulling the micro folds of the cap regions by applying suction. In a typical method, the cap regions include a plurality of overlapping ridges inclined relative to the MD sheet.

An additional aspect of the present invention is a method of manufacturing a fabric-creped absorbent cellulose sheet with improved dispensing characteristics, comprising: a) compressive dewatering of the pulp to form an incipient web; b) applying a dehydrated web to a transfer surface moving at a first speed; c) fabric creping of the web from the transfer surface at a consistency of from about 30% to about 60% using a patterned creping fabric, the creping step being under pressure in the fabric creping clip defined between the transfer surface and the creping fabric, where the fabric moves from the second a speed less than the speed of said transfer surface. The fabric pattern, pressure parameters, speed difference and web consistency are selected so that the web is creped from the transfer surface and transferred to the creping fabric. This method also includes d) adhesion of the web on a drying cylinder with a resinous adhesive coating composition; e) drying the web on a drying cylinder; and f) peeling the web from the drying cylinder, where the paper pulp, creping fabric and creping adhesive are selected, and the speed difference, pressing parameters and web consistency, thickness and base weight are controlled so that the bending length MD of the dried web is at least about 3, 5 cm, and the web has a paper-fiber mesh consisting of (i) a plurality of fiber-rich, extending across the machine direction (CD), bonnet regions with a relatively high local base weight, connecting through (ii) a plurality of elongated densified areas of compressed paper fibers. Elongated densified areas have a relatively low local base weight and are generally oriented along the machine direction (MD) of the sheet; elongated densified areas are further characterized by an MD / CD ratio of at least 1.5. The bending length MD of the dried web is from about 3.5 cm to about 5 cm in many cases, for example from about 3.75 to about 4.5 cm. This method can function with tissue creping from about 2% to about 20%, and functions with tissue creping from about 3% to about 10% in a typical embodiment.

Another aspect of the present invention is a method for manufacturing a tissue-creped absorbent cellulosic sheet, comprising: a) compressing the dewatering of the pulp to form a nascent web having an obviously random distribution of paper fiber orientation; b) applying a dehydrated web having an obviously random distribution of the orientation of the paper fiber on a transfer surface moving at a first speed; c) fabric creping of a given web from the transfer surface at a consistency of from about 30% to about 60%, the creping step being under pressure in a fabric crepe clamp defined between the transfer surface and the creping fabric, where the fabric moves at a second speed less than speed of said transport surface. The fabric pattern, pressure parameters, speed difference and web consistency are selected so that the web is creped from the transfer surface and redistributed onto the creping fabric, forming a web with a displaceable mesh having a lot of connecting areas with different local base weights, including at least (i) a lot fiber enriched areas with a high local base weight, connected by (ii) a plurality of elongated densified areas of compressed paper fiber, and elongated densified e areas have a relatively low local base weight and are generally oriented along the machine direction (MD) of the sheet. The elongated densified areas are further characterized by an MD / CD ratio of at least 1.5. This method further includes d) drying the web; and then e) stretching the web along its MD, where the displaceable mesh of the web is characterized in that it contains a coherent fiber matrix that exhibits increased porosity during stretching. Suitably, the at least partially dried web is stretched along its MD by at least about 10% after fabric creping, or the fabric is stretched in the machine direction by at least about 15% after fabric creping. The canvas can be pulled in its MD by at least about 30% after tissue creping; at least about 45% after tissue creping; and the web can be stretched in its MD to about 75% or more after tissue creping, provided that a sufficient amount of creping fabric has been applied.

Another method of manufacturing a tissue-creped absorbent cellulosic sheet of the present invention includes: a) compressive dewatering of the pulp to form an incipient web having an obviously random distribution of paper fiber orientation; b) applying a dehydrated web having an obviously random distribution of the orientation of the paper fiber on a transfer surface moving at a first speed; c) fabric creping of the web from the transfer surface at a consistency of from about 30% to about 60%, the creping step being under pressure in a fabric crepe clamp defined between the transfer surface and the creping fabric, where the fabric moves at a second speed less than the speed of said transfer surface; d) applying the canvas to the Yankee cylinder; f) creping the canvas from the Yankee cylinder; and f) winding the web onto a spool; moreover, the fabric pattern, pressure parameters, speed difference and the consistency and composition of the fabric is chosen so that: i) the fabric is attached from the transfer surface and redistributed onto the creping fabric, forming a fabric with a variation of the local base weight, including at least (A) a lot of fiber-rich areas with high local base weight; (B) a plurality of elongated regions having a relatively low local base weight and generally oriented along the machine direction (MD) of the sheet; and ii) the method exhibits a thickness increment /% winding creping ratio of at least 1.5. Typically, this method demonstrates a ratio of thickness increase /% of winding creping at least 2; for example, the ratio of the increase in thickness /% of winding creping, comprising at least 2.5 or 3. Typically, this method demonstrates the ratio of the increase in thickness /% of winding creping, ranging from about 1.5 to about 5, and operates with a ratio of fabric creping / winding creping, from about 1 to about 20. This method can work with a ratio of fabric creping / reeling creping from about 2 to about 10, for example, with a ratio of t channel creping / reeling creping, comprising from about 2.5 to about 5.

The above and further features of the present invention are further illustrated in the following discussion.

The terminology used here is given in its usual meaning consistent with the typical definitions set forth below; mg stands for milligrams, and m ² stands for square meters and so on.

The rate of “addition” of creping adhesive is calculated by dividing the rate of application of the adhesive (mg / min) by the surface area of the drying cylinder passing under the boom of the spray application device (m ² / min). The resinous adhesive composition most preferably consists essentially of a polyvinyl alcohol resin and a polyamide epichlorohydrin resin, where the weight ratio of the polyvinyl alcohol resin to the polyamide epichlorohydrin resin is from about 2 to about 4. The creping adhesive may also include a modifier sufficient to maintain good American tissue transfer drying cylinder; typically less than 5% by weight modifier and more preferably less than about 2% by weight modifier for refined products. For knife-creped products, 15% -25% of the modifier or more may be used.

In this description and the claims, when the authors refer to a nascent web having an obviously random distribution of fiber orientation (or use similar terminology), the authors mean the distribution of fiber orientation that occurs when forming technologies are used to deposit paper pulp onto the forming fabric. Microscopic examination of these fibers reveals random orientation, even though depending on the speed of the jet relative to the mesh, they can have a significant inclination in the machine direction, making the tensile strength of the web in the machine direction higher than the tensile strength in the transverse direction.

Unless otherwise indicated, “base weight,” BWT, bwt, and so on, refers to a mass of 3,000 square feet (279 m ² ) of product foot. Similarly, “foot” means a 3000 square foot (279 m ² ) foot, unless otherwise indicated, for example, in grams per square meter (g / m ² ). Consistency means% solids of the incipient web, for example, calculated on a completely dry basis. “Air-dry” means including residual moisture as agreed up to about 10% moisture for pulp and up to about 6% for paper. An incipient web having 50% water and 50% completely dry pulp has a consistency of 50%.

The term “cellulosic”, “cellulosic sheet” and the like means the inclusion of any product containing paper fiber having cellulose as the main component. “Paper fibers” include initial pulps and reusable (secondary) cellulosic fibers, or fiber mixtures containing cellulosic fibers. A fiber suitable for the manufacture of the webs of this invention includes: non-wood fiber such as cotton fiber or cotton derivatives, abacus fiber, kenaf, sabai grass, flax, esparto grass, straw, jute, hemp, oilcake, milky fluff and fiber pineapple leaves; and wood fiber, such as fiber obtained from deciduous and coniferous trees, including softwood fiber, such as northern and southern softwood kraft fiber; hardwood fiber such as eucalyptus, maple, birch, aspen or the like. Paper fibers can be released from their starting material using any of a number of chemical pulping methods related to a method used in the art using sulphate, sulphite, polysulphide, soda, etc. The pulp can be bleached, if desired, by chemical means, including the use of chlorine, chlorine dioxide, oxygen, alkali metal peroxide and so on. The products of the present invention may contain a mixture of conventional fibers (originating from the original pulp or reusable sources) and highly rough, lignin-rich, tubular fibers, mechanical pulps, such as bleached chemical thermomechanical pulp (BCMP). “Paper composition” and similar terminology refers to aqueous compositions including paper fibers, optional resins for wet strength, baking powder and the like for the manufacture of paper products. Reusable fibers typically have more than 50% by weight of hardwood fibers and can have 75% -80% or more hardwood fibers.

The term “compressive dewatering of a web or paper pulp” as used herein refers to mechanical dehydration by wet pressing on a dewatering felt, for example, in some embodiments, by applying mechanical pressure continuously applied to the surface of the web in the form of a clamp between the press roll and the press bed, where the web is in contact with paper felt. The term "compressive dehydration" is used to distinguish from methods where the initial dehydration is carried out mainly by thermal means, as is the case, for example, in US Pat. No. 4,529,480, Trokhan and US Pat. No. 5,607,551, Farrington et al . The compressive dewatering of the web thus relates, for example, to removing water from the resulting web having a consistency of less than 30% or close by applying pressure thereto and / or increasing the consistency of the web by about 15% or more by applying to it pressure, that is, increasing the consistency, for example, from 30% to 45%.

Crepe fabric and similar terms refer to a fabric or tape that carries a pattern suitable for carrying out the method of the present invention, and is preferably sufficiently permeable so that the fabric can be dried while it is held in the crepe fabric. In cases where the web is transferred to another fabric or surface (other than a creping fabric) for drying, the creping fabric may have less permeability.

"Fabric side" and similar terms refer to the side of the web that is in contact with the creping fabric. The “desiccant side” or “American drying cylinder side” is the side of the web in contact with the drying cylinder, usually opposite the fabric side of the web.

Feet / min refers to feet per minute (data is also sometimes expressed in meters per minute (m / min)); whereas ft / s refers to feet per second.

MD stands for machine direction, and CD stands for transverse machine direction.

Clamp parameters include, without limitation, clamp pressure, clamp width, reverse shaft hardness, creping shaft hardness, tissue entry angle, tissue exit angle, uniformity, clamp penetration, and speed difference between the clamp surfaces.

Clamp width means the MD length at which the clamped surfaces are in contact.

“Advantageously” means more than 50% of a particular component by weight, unless otherwise indicated.

The transfer surface refers to the surface from which the web is fastened into a creping fabric. The transfer surface may be the surface of a rotating drum, as described below, or may be the surface of a continuous smooth moving tape or other moving fabric, which may have a surface texture, etc. A transfer surface is needed to support the web and facilitate creping with solid protrusions, as will be understood from the discussion that follows.

The thickness and / or volume provided herein may be measured for 8 or 16 sheets as indicated. The sheets are folded into a bundle, and the thickness measurement is carried out near the central part of the bundle. Preferably, test samples are conditioned in the atmosphere at 23 ° C ± 1.0 ° C (73.4 ± 1.8 ° F) at 50% relative humidity for at least about 2 hours and then measured using the Thwing-Albert Model 89-II-JR or Progage electronic thickness gauge with heels 2 inches (50.8 mm) in diameter, with a constant load of 539 ± 10 grams and a drop rate of 0.231 inches / sec (5.87 mm / sec). To test the final product, each sheet of the test product must have the same number of layers as the product sold. For testing, eight sheets are usually selected and stacked together. To test wipes, wipes unfold before folding. To test the warp sheet from winding machines, each test sheet must have the same number of layers as that produced by the winding machine. To test a backing sheet from a paper machine reel, it is necessary to use single layers. Sheets are stacked aligned in MD. On a custom embossed or printed product, try to avoid taking measurements in these areas, if at all possible. Volume can also be expressed in units of volume / mass by dividing the thickness by the base weight.

The characteristic local base weights and differences between them are calculated by measuring the local base weight in 2 or more typical areas with low base weight inside areas with low base weight and compare this average base weight with the average base weight in two or more typical areas inside areas with relatively high local base weight. For example, if typical areas within areas of low base weight have an average base weight of 15 lb / 3000 ft ² feet (24.4 g / m ² ) and the average measured local base weight for typical areas within areas with a relatively high local base weight is 20 lb / 3000 ft ² feet (32.5 g / m ² ), typical areas within areas with a high local base weight have a characteristic base weight of ((20-15) / 15) × 100% or 33% higher than typical areas inside areas with low base weight. Preferably, the local base weight is measured using beta particle attenuation technology as described herein.

The length of the MD bend (cm) is determined according to the testing method ASTM D 1388-96, option with bracket. The bending lengths shown refer to MD bending lengths unless the CD bending length is specifically indicated. The MD bend length test is performed with a bend meter with a bracket available from Research Dimensions, 1720 Oakridge Road, Neenah, Wisconsin, 54956, which is essentially the apparatus shown in this ASTM test method, point 6. The tool is placed on a stable surface, horizontal position is checked by the built-in level bubble. The bend angle indicator is set 41.5 ° below the surface level of the sample. This is achieved by installing the prismatic support accordingly. The sample was cut with a one inch (2.54 cm) JD strip cutter, available from Thwing-Albert Instrument Company, 14 Collins Avenue, W. Berlin, NJ 08091. Six (6) samples were cut pieces of 1 inch × 8 inches (2.54 cm × 20.32 cm) in the machine direction. Samples are conditioned at 23 ° C ± 1 ° C (73.4 ° F ± 1.8 ° F) at 50% relative humidity for at least two hours. For machine direction samples, a longer dimension is parallel to the machine direction. Samples should be flat, free from wrinkles, bends or tears. Side images are also marked. The sample is placed on the horizontal platform of the meter, aligning the edge of the sample with the right edge. A movable slider is placed on the sample, being careful not to change its initial position. The right edge of the sample and the movable slider must be installed at the right edge of the horizontal platform. The movable slider is shifted to the right in a smooth, slow manner at approximately 5 inches / minute (12.7 cm / minute) until the sample touches the prismatic support. The overhang length is recorded to the nearest 0.1 cm. This is done by reading the left edge of the movable slider. Three samples are preferably tested with the Yankees side up, and three samples are preferably tested with the Yankees side down on a horizontal platform. The length of the MD bend is indicated as the average overhang length in centimeters divided by two, taking into account the position of the bend axis.

The water absorption rate or WAR is measured in seconds and represents the time it takes a sample to absorb a 0.1 gram drop of water placed on its surface using an automatic syringe. Test samples are preferably conditioned at 23 ° C ± 1 ° C (73.4 ° ± 1.8 ° F) at 50% relative humidity for 2 hours. For each sample, 4 test pieces of 3 × 3 inches (7.62 × 7.62 cm) were prepared. Each piece is placed in a sample holder so that a high-intensity lamp is directed toward the sample. 0.1 ml of water is placed on the surface of the sample and the stopwatch is turned on. When the water is absorbed, which is indicated by the absence of additional reflection of light from the drop, the stopwatch is stopped and the time is recorded to the nearest 0.1 second. This procedure is repeated for each piece, and the results are averaged for the sample. WAR is measured according to the TAPPI T-432 cm-99 method.

Dry tensile strength (MD and CD), tensile strength, their ratio, modulus, tensile modulus, stress and strain are measured with a standard Instron test device or other suitable tensile elongation meter, which can be configured in a variety of ways, usually using strips tissue paper or towels 3 or 1 inch wide (7.62 or 2.54 cm), conditioned in the atmosphere at 23 ° C ± 1 ° C (73.4 ± 1.8 ° F) at 50% relative humidity for 2 hours. A tensile test is carried out at a slider speed of 2 inches / min (5.1 cm / min). Tear modulus is expressed in grams / 3 inches /% strain ((grams / cm) /% strain). % strain is dimensionless and requires no refinement. Unless otherwise indicated, the values are the values of the gap. GM refers to the square root of the result of MV and CB values for a particular result.

Stretch ratios are simply ratios of quantities determined using the methods described above. Unless otherwise specified, the tensile property is a dry sheet property.

The wet stretch of the fabric of the present invention is measured using a three-inch (7.62 mm) wide strip of fabric that is folded into a loop, fastened with a special clamp called the Finch Cup, then immersed in water. A Finch Cup, which is available from the Thwing-Albert Instrument Company of Philadelphia, Pa., Is mounted on a tensile tester equipped with a 2.0 lb (0.907 kg) load cell with a Finch Cup flange clamped to the bottom of the appliance and the ends of the fabric loop clamped to the top tensile tester clamp. The sample is immersed in water, which is adjusted to a pH of 7.0 ± 0.1, and tensile after an immersion time of 5 seconds. The results are expressed in g / 3 "(g / cm), dividing by two to account for the loop properly.

A “fabric creping ratio” is an expression of the difference in speed between the creping fabric and the forming mesh, and is usually calculated as the ratio of the web speed immediately before the fabric creping and the web speed immediately after the fabric creping, and the forming mesh and transfer surface usually, but not necessarily, function at the same speed:

Fabric creping ratio = transfer cylinder speed · creping fabric speed

Fabric creping can also be expressed as percent, calculated as:

Fabric creping = [Ratio of fabric creping - 1] × 100

The canvas creped from the transfer cylinder at a surface speed of 750 ft / min (228.8 m / min) onto the fabric at a speed of 500 ft / min (152.5 m / min) has a fabric creping ratio of 1.5 and fabric creping of 50%.

For winding creping, winding creping ratios are usually calculated as Yankee speed divided by winding speed. To express winding creping as a percentage, 1 is subtracted from the winding creping relationship, and the result is multiplied by 100%.

The fabric crepe / reel crepe ratio is calculated by dividing the fabric crepe by reel crepe.

The ratio of the increase in thickness /% reeling crepe is calculated by dividing the observed increase in thickness in mil / 8 sheets (mm / 8 sheets) by% reeling creping. The increase in thickness is determined by comparison with similar operating conditions without winding creping. See Table 13 below.

The ratio of in-line or general creping is calculated as the ratio of the speed of the forming mesh to the winding speed, and% of total creping is:

Inline creping = [inline creping -1] × 100

A method with a forming mesh speed of 2000 ft / min (610 m / min) and a winding speed of 1000 ft / min (305 m / min) has a flow or full creping ratio of 2 and 100% full creping.

PLI or pli means pounds of force per linear inch (kg of force per linear centimeter (plcm)). The applied method differs from other methods in part, since tissue creping is performed under pressure in the creping clamp. Typically, a sharp transfer is carried out using suction to facilitate peeling of the web from the donor tissue, and then its attachment to the host or receptor tissue. On the contrary, absorption is not required at the stage of fabric creping, respectively, when the authors indicate that fabric creping is leaking "under pressure", the authors indicate loading of the receiving tissue relative to the transfer surface, although the aid of absorption can be used with an additional complication of the system, provided that the amount of absorption is not sufficient to undesirably affect the rearrangement or rearrangement of the fiber.

Pusey and Jones hardness (P&J) - (indentation) is measured according to ASTM D 531 and is indicated in the indentation number (standard sample and conditions).

Speed difference means the difference in linear speed.

The porosity and / or empty space fraction indicated below is determined by saturating the sheet with non-polar POROFIL® fluid and measuring the amount of fluid absorbed. The volume of absorbed liquid is equivalent to the volume of voids inside the sheet structure. % mass increase (PWI) is expressed in grams of absorbed liquid per gram of fiber in the sheet structure times 100 by the following. More specifically, for each test sample of a single-layer sheet, 8 sheets are selected and an area of 1 inch × 1 inch (1 inch in the machine direction and 1 inch in the transverse direction) is cut (2.54 cm by 2.54 cm (2.54 cm in machine direction and 2.54 cm in the transverse direction)). For samples of multilayer products, each layer is measured as a separate object. Multilayer samples must be divided into individual unit layers, and 8 sheets from each position of the layer are used for testing. The dry weight of each test sample is weighed and carried to the nearest value with an accuracy of 0.0001 grams. A sample was placed in a cuvette containing POROFIL® fluid having a specific gravity of approximately 1.93 grams per cubic centimeter available from Coulter Electronics Ltd., Northwell Drive, Luton, Beds, England; Part 9902458). After 10 seconds, capture the sample at the very edge (1-2 millimeters) of one corner with tweezers and remove it from the liquid. Hold the sample with this angle up and allow excess fluid to drip for 30 seconds. Lightly touch (contact less than 1/2 second) the bottom corner of the sample with filter paper # 4 (Whatman Lt., Maidstone, England) to remove any excess of the last partial drop. Immediately weigh the sample for 10 seconds, recording the mass to the nearest value with an accuracy of 0.0001 grams. PWI for each sample, expressed in grams of POROFIL® fluid per gram of fiber, is calculated as follows:

PWI = [(W ₂ -W ₁ ) / W ₁ ] × 100,

Where

"W ₁ " expresses the dry weight of the sample in grams; and

"W ₂ " expresses the wet weight of the sample in grams.

The PWI for all eight individual pieces is determined as described above, and the average of the eight pieces represents the PWI for the sample.

The empty volume fraction is calculated by dividing the PWI by 1.9 (liquid density), expressed as a percentage, while porosity (mg / mg) is simply a fraction of the mass increase; that is, PWIs are divided by 100.

The creping adhesive used to fix the web to the Yankee cylinder is preferably hygroscopic, re-wetted, substantially non-crosslinked adhesive. Examples of preferred adhesives are adhesives that include polyvinyl alcohol from the general class described in US Pat. No. 4,528,316 to Soerens et al. Other suitable adhesives are described in the co-pending, provisional US patent application serial number 60/372255, filed April 12, 2002, entitled "Improved creping adhesive modifier and method for producing paper products" (Attorney Docket No. 2394). The descriptions of the '316 patent and the' 255 patent application are hereby incorporated by reference. Suitable adhesives are provided, if necessary, with modifiers and so on. It is preferable to use the crosslinking agent and / or modifier in the adhesive sparingly or not to use it at all.

Creping adhesives may contain a thermosetting or non-thermosetting resin, a film-forming semi-crystalline polymer and, if necessary, an inorganic crosslinking agent, as well as modifiers. If necessary, the creping adhesive of the present invention may also include other components, including, but not limited to, hydrocarbon oils, surfactants, or plasticizers. Further details regarding creping adhesives applicable to the present invention are found in co-pending, provisional application No. 60/779614, filed March 6, 2006 (Attorney Docket No. 2014; GP-06-1), the disclosure of which is incorporated herein by reference.

The creping adhesive may be applied as a single composition or may be applied as its constituent parts. More specifically, the polyamide resin can be applied separately from polyvinyl alcohol (PVOH) and the modifier.

When using a creping knife, a conventional coating packet is suitably applied at full coverage (addition as calculated above) 54 mg / m ² with 32 mg / m ² PVOH (Celvol 523) / 11.3 mg / m ² PAE (Hercules 1145) and 10.5 mg / m ² modifier (Hercules 4609VF). A preferred coating for the peeling method can be applied at a value of 20 mg / m ² with 14.52 mg / m ² PVOH (Celvol 523) / 5.10 mg / m ² PAE (Hercules 1145) and 0.38 mg / m ² modifier ( Hercules 4609VF).

According to the present invention, an absorbent paper web is made by dispersing paper fibers in an aqueous paper pulp (slurry) and depositing the aqueous paper pulp on a forming grid of a paper machine. Any suitable molding scheme may be used. For example, a lengthy but non-exhaustive list, in addition to the forming long mesh machine, includes a sickle forming machine, a C-folding double-mesh forming machine, an S-folding double-mesh forming machine, or a suction roll forming machine. The forming fabric may be any suitable perforated element, including single layer fabrics, double layer fabrics, three layer fabrics, and the like. An incomplete description of the prior art in the field of forming tissue includes US Pat. Nos. 4,157,276; 4,605,585; 4,161,195; 3,545,705; 3,549,742; 3,858,623; 4,041,989; 4,071,050; 4,112,982; 4,149,571; 4,182,381; 4,184,519; 4,314,589; 4,359,069; 4,376,455; 4,379,735; 4,453,573; 4,563,052; 4,592,395; 4,611,639; 4,640,741; 4,709,732; 4,759,391; 4,759,976; 4,942,077; 4,967,085; 4,998,568; 5016678; 5,045,525; 5066532; 5098519; 5,103,874; 5,114,777; 5,167,261; 5,199,261; 5,199,467; 5,211,815; 5219004; 5,245,025; 5,277,761; 5328565 and 5379808, all of which are hereby incorporated by reference in their entirety. One forming fabric, particularly applicable to the present invention, is Voith Fabrics Forming Fabric 2164 manufactured by Voith Fabrics Corporation, Shreveport, LA.

Foaming of aqueous paper pulp on a forming mesh or fabric can be used as a means of regulating the permeability or porosity of the sheet during tissue creping. Foaming technologies are described in US patent No. 4543156 and Canadian patent No. 2053505, descriptions of which are incorporated herein by reference. Foamed fibrous paper pulp is made from an aqueous suspension of fibers mixed with a foamed liquid carrier immediately before it is introduced into the headbox. The pulp suspension supplied to the system has a consistency in the range of from about 0.5 to about 7 wt.% Fiber, preferably in the range of from about 2.5 to about 4.5 wt.%. The pulp suspension is added to a foamed liquid containing water, air and a surfactant containing from 50 to 80% air by volume, forming a foamed fibrous paper pulp having a consistency in the range of from about 0.1 to about 3 wt.% Fiber, by simple mixing as a result of natural turbulence and inherent mixing in the elements of the method. Adding pulp in the form of a suspension with a low consistency leads to an excess of foamed liquid returned from the forming mesh. Excessive foamed liquid is discharged from the system and can be used elsewhere or processed to recover a surfactant from it.

The pulp may contain chemical additives that alter the physical properties of the resulting paper. These chemical additives are well known to those skilled in the art and can be used in any known combination. Such additives can be surface modifiers, softeners, disintegrants, hardeners, latexes, mufflers, brighteners, dyes, pigments, lubricants, barrier-forming chemicals, retention agents, insolubility agents, organic or inorganic crosslinkers, or combinations thereof; said chemicals optionally contain polyols, starches, PPG esters, PEG esters, phospholipids, surfactants, GMPC (hydrophobically modified cationic polymers), GMAP (hydrophobically modified anionic polymers) or the like.

Pulp can be mixed with strength-regulating agents, such as wet strength agents, dry strength agents and disintegrants / softeners, etc. Suitable wet strength agents are known to those skilled in the art. An extensive, but not exhaustive list of useful hardeners includes urea-formaldehyde resins, melamine-formaldehyde resins, glyoxylated polyacrylamide resins, polyamide-epichlorohydrin resins and the like. Thermosetting polyacrylamides are prepared by reacting acrylamide with diallyldimethylammonium chloride (DADMAC) to give a cationic polyacrylamide copolymer, which ultimately reacts with glyoxal to produce a cationic crosslinked, wet-resistant resin, glyoxylated polyacrylamide. These materials are generally described in US patent No. 3556932, Coscia et al . and 3556933, Williams et al ., both of which are incorporated herein by reference in its entirety. Resins of this type are commercially available under the trade name PAREZ 631 NC from Bayer Corporation. Various acrylamide / -DADMAC / glyoxal molar ratios can be used to prepare crosslinked resins that are useful as wet strength agents. In addition, other dialdehydes can be substituted for glyoxal to obtain thermosetting wet strength characteristics. Especially suitable are polyamide-epichlorohydrin wet strength resins, an example of which are sold under the trade name Kymene 557LX and Kymene 557H from Hercules Incorporated of Wilmington, Delaware and Amres® from Georgia-Pacisic Resins, Inc. These resins and a method for manufacturing these resins are described in US Pat. No. 3,700,623 and US Pat. No. 3,772,076, each of which is incorporated herein by reference in its entirety. An extensive description of polymer-epichlorohydrin resins is given in Chapter 2: Alkali-cured polymer amine-epichlorohydrin by Espy in Wet Strength Resins and Their Application (L. Chan, Editor, 1994), incorporated herein by reference in its entirety. A moderately detailed list of wet strength resins is described by Westfeld in Cellulose Chemistry and Technology Volume 13, p.813, 1979, which is also incorporated herein by reference.

Suitable temporary wet strength agents may also be included, particularly in applications where disposable towels or, more typically, fabrics with a permanent wet strength resin should be avoided. A detailed but not exhaustive list of applicable wet strength temporary agents includes aliphatic and aromatic aldehydes, including glyoxal, malondialdehyde, succinic dialdehyde, glutaraldehyde and dialdehyde starches, as well as substituted or reacted starches, disaccharides, polysaccharides, polysaccharides reactions of monomers or polymers having aldehyde groups and, if necessary, nitrogen groups. Typical nitrogen-containing polymers that can suitably react with aldehyde-containing monomers or polymers include vinyl amides, acrylamides and the corresponding nitrogen-containing polymers. These polymers give a positive charge to the aldehyde-containing reaction product. In addition, other commercially available temporary wet strength agents such as PAPEZ 745 manufactured by Bayer may be used along with the agents described, for example, in US Pat. No. 4,605,702.

Temporary wet strength resin can be any resin from a variety of water-soluble organic polymers containing aldehyde groups and cationic groups used to increase the dry and wet tensile strength of paper products. Such resins are described in US patent No. 4675394; 5,240,562; 5,138,002; 5,085,736; 4,981,557; 5,008,344; 4,603,176; 4,983,748; 4,866,151; 4804769 and 5217576. Modified starches sold under the trademarks CO-BOND® 1000 and CO-BOND® 1000 Plus from National Starch and Chemical Company of Dridgewater, N.J., may be used. Before use, a cationic aldehyde water-soluble polymer can be prepared by preheating an aqueous suspension of approximately 5% solids, maintained at a temperature of about 240 ° Fahrenheit (116 degrees Celsius) and a pH of about 2.7 for about 3.5 minutes. Finally, the suspension may be quenched and diluted with water to give a mixture of about 1.0% solids at less than about 130 ° F (116 ° C).

Other temporary wet strength agents, also available from the National Starch and Chemical Company, are sold under the trademarks CO-BOND® 1600 and CO-BOND® 2300. These starches are used as aqueous colloidal dispersions and do not need to be preheated before use.

Suitable dry strength agents include starch, guar gum, polyacrylamides, carboxymethyl cellulose and the like. Carboxymethyl cellulose is particularly useful, an example of which is sold under the trade name Hercules CMC from Hercules Incorporated of Wilmington, Delaware. In one embodiment, the pulp may contain from about 0 to about 15 lb / ton (from about 0 to about 7.5 kg / ton) of dry strength agent. In another embodiment, the pulp may contain from about 1 to about 5 lb / ton (from about 0.5 to about 2.5 kg / ton) of a dry strength agent.

Suitable disintegrants are also known to those skilled in the art. Baking powder or softeners can also be introduced into the pulp or sprayed onto the canvas after it is formed. The present invention can also be used with softener materials, including, but not limited to, a class of amidoamine salts derived from, but not limited to, amine partially neutralized amines. Such materials are described in US patent No. 4720383. Evans, Chemistry and Industry , 5 July 1969, pp. 893-903; Egan, J. Am. Oil Chemist's Soc., Vol . 55 (1978), pp. 118-121; and Trivedi et al., J. Am. Oil Chemist's Soc. , June 1981, pp.754-756, incorporated by reference in their entirety, indicate that emollients are often available commercially only as complex mixtures, rather than as individual compounds. Although the following discussion will focus on the predominant particles, it should be understood that commercially available mixtures will usually be practiced.

Quasoft 202-JR is a suitable emollient material which can be obtained by alkylation of the condensation product of oleic acid and diethylene triamine. Synthesis conditions using a shortage of an alkylation agent (e.g. diethyl sulfate) and only one alkylation step followed by adjusting the pH to protonate unleaded particles give a mixture consisting of cationic leaded and cationic unleaded particles. A small fraction (e.g., approximately 10%) of the amidoamine obtained is cyclized to imidazoline compounds. Since only the imidazoline portions of these materials are quaternary ammonium compounds, the compositions are generally pH sensitive. Therefore, in the practice of the present invention with this class of chemicals, the pH in the headbox should be from about 6 to 8, more preferably from 6 to 7, and most preferably from 6.5 to 7.

Quaternary ammonium compounds, such as quaternary dialkyldimethylammonium salts, are also suitable, especially when the alkyl groups contain from about 10 to 24 carbon atoms. These compounds are preferred due to their relative insensitivity to pH.

Biodegradable emollients can be used. Typical biodegradable cationic emollients / disintegrants are described in US Pat. Nos. 5,312,522; 5,415,737; 5262007; 5,264,082; and 5223096, all of which are incorporated herein by reference in their entirety. These compounds are biodegradable quaternary ammonium diesters, quaternized amino esters and esters based on biodegradable vegetable oils, functionalized quaternary ammonium chloride and dierucyldimethylammonium diester chloride, and are typical biodegradable softeners.

In some embodiments, a particularly preferred disintegrant composition includes a quaternary amine component as well as a nonionic surfactant.

The nascent web can be dehydrated by squeezing on the felt of a paper machine. Any suitable felt may be used. For example, felts may have two-layer base weaves, three-layer base weaves, and layered base weaves. Preferred felts are felts having a design with layered base weaves. Wet pressing felt, which may be particularly suitable with the present invention, is Vector 3 manufactured by Voith Fabric. The level of technology in the field of felt for pressing includes US patent No. 5657797; 5,368,696; 4,973,512; 5,023,132; 5,225,269; 5,182,164; 5,372,876; and 5618612. Felt for differential pressing, described in US patent No. 4533437, Curran et al., can also be used.

Suitable creping or texturing fabrics include monolayer, or multilayer, or complex, preferably open, cellular structures. The fabric design itself is less important than the topography of the creping surface in the creping clip, as discussed in more detail below. Long MD fists with slightly lower CD fists are extremely preferred for many products. The fabrics may have at least one of the following characteristics: (1) on the side of the creping fabric that is in contact with the wet web (the “upper” side), the number of strands in the machine direction (MD) per inch (mesh) is from 10 to 200 (locks per cm (mesh) from 3 to 18) and the number of locks in the transverse direction (CD) per inch (count) is from 10 to 200 (locks per cm (count) from 3 to 18); (2) the diameter of the strand is usually less than 0.050 inches (0.13 cm); (3) on the upper side, the distance between the highest point MD of the fists and the highest point CD of the fists is from about 0.001 to about 0.02 or 0.03 inches (from about 0.0025 to about 0.05 or 0.08 cm); (4) between these two levels there can be fists formed by MD or CD strands, which gives a topography with three-dimensional hills / valleys, which is transmitted to the sheet; (5) the fabric can be oriented in any suitable way to achieve the desired effect in processing and product properties; long fists of warp strands can be on the upper side, increasing MD protrusions in the product, or long fists of warp strands can be on the upper side, if more CD protrusions are desired, affecting creping characteristics when the web is transferred from the transfer cylinder to the creping fabric; and (6) the fabric can be made to have a specific geometric pattern that is pleasing to the eye, which is usually repeated every two to 50 strands of the warp. A particularly preferred fabric is W013 Albany International multilayer fabric. Such fabrics are formed from monofilament polymer fibers having diameters typically in the range of from about 0.25 mm to about 1 mm. A particularly preferred fabric is shown in Fig. 7 and subsequent.

To provide additional volume, the wet web is creped into a textured fabric and expanded into the textured fabric by suction, for example.

If a long mesh machine or a molding machine with other gaps is used, the nascent web can be treated with suction nests and steam jackets until it reaches a solids content suitable for transfer to dewatering felt. The nascent fabric can be transferred to the felt by suction. In a sickle-forming machine, the use of suction is not necessary, since a nascent web is formed between the forming fabric and the felt.

A preferred method of manufacturing the proposed products includes compressive dewatering of pulp having an obviously random distribution of fiber orientation, and fabric creping of the web so as to redistribute the pulp in order to achieve the desired properties. Significant features of a typical unit 40 to obtain the proposed products are shown in figure 4. The assembly 40 includes a felt 42 for making paper, a suction shaft 46, a pressure pad 50 and a return shaft 52. In addition, a creping shaft 62, a creping fabric 60, and an optional suction box 66 are provided.

In operation, the felt 42 moves the nascent web 44 around the suction shaft 46 into the squeezing clamp 48. In the squeezing clamp 48, the web is dehydrated by compression and transferred to the return shaft 52 (sometimes referred to below as the transfer shaft), where the web is transferred to the creping fabric. In the creping clip 64, the web 44 is moved onto the fabric 60, as discussed in more detail below. A creping clamp is defined between the return shaft 52 and the creping fabric 60, which is compressed relative to the shaft 52 by the creping shaft 62, which may be a shaft coated with soft material, which is also discussed below. After transferring the web to the fabric 60, the suction box 66 can be used to apply suction to the sheet to extend the microfolds, if desired.

A paper machine suitable for manufacturing the product of the present invention may have various configurations, as can be seen in FIGS. 5 and 6, discussed below.

5 shows a paper machine 110 for use in accordance with the present invention. The papermaking machine 110 is a three-loop fabric machine having a forming section 112, commonly referred to in the art as a sickle-forming machine. The forming section 112 includes a forming grid 122 supported by a plurality of shafts, such as shafts 132, 135. The forming section also includes a forming shaft 138 that supports the felt 42 of the paper machine, so that the web 44 is formed directly on the felt 42. Mileage 114 the felt extends to the press pad section 116, where the wet web is deposited on the return shaft 52 and subjected to wet compression simultaneously with the transfer. The web 44 is then secured to the fabric 60 before being deposited on the Yankee cylinder 120 in another compression nip 182 using a creping adhesive as described above. The system includes a rotary suction shaft 46 in some embodiments; however, a three-loop system can be organized in a variety of ways where a rotating shaft is not necessary. This feature is especially important in connection with the reconstruction of the paper machine, since the cost of moving related equipment, i.e. pulp preparation and fiber processing equipment and / or large and expensive drying equipment, such as a Yankee cylinder or multiple drum dryers, will make the reconstruction unnecessarily expensive if the improvements are not compatible with existing equipment.

Figure 6 schematically shows a paper machine 210, which can be used to implement the present invention. The paper machine 210 includes a forming section 212, a squeezing section 40, a creping shaft 62, as well as a drum-drying section 218. The forming section 212 includes: a headbox 220, a forming fabric or mesh 222, which is supported by a plurality of shafts, providing a forming table 212. A forming shaft 224, supporting shafts 226, 288, as well as a transfer shaft 230 are also provided.

The squeezing section 40 includes a felt 42 of a paper machine supported on rollers 234, 236, 238, 240 and a pressure pad shaft 242. The pressure pad shaft 242 includes a pad 244 for squeezing the web relative to the transfer drum or shaft 52. The transfer shaft or drum 52 may be heated, if desired. In one preferred embodiment, the temperature is controlled so as to maintain a moisture profile in the web so that an ordered sheet is obtained having a local change in base weight that does not extend to the surface of the web in contact with cylinder 52. Typically, steam is used to heat cylinder 52, such as indicated in US patent No. 6379496, Edwards et al . The shaft 52 includes a transfer surface 248 on which the web is deposited during manufacture. The creping shaft 62 supports, in part, the creping fabric 60, which is also supported on the plurality of shafts 252, 254, and 256.

The drying section 218 also includes a plurality of drum dryers 258, 260, 262, 264, 266, 268 and 270, as shown in the drawing, where the drums 266, 268 and 270 are in the first tier and the drums 258, 260, 262 and 264 are in the second tier. The drums 266, 268 and 270 are in direct contact with the web, while the drums in the other tier are in contact with the fabric. In this two-tier arrangement, when the web is separated from the drums 260 and 262 by a cloth, it is sometimes advantageous to provide forced air dryers at 260 and 262, which can be drilled drums, so that the air flow is indicated schematically as 261 and 263.

Additionally, a winding section 272 is provided, which includes a guide shaft 274 and a receiving coil 276, shown schematically in the drawing.

The paper machine 210 operates so that the web is transported in the machine direction indicated by arrows 278, 282, 284, 286 and 288, as seen in FIG. Pulp with a low consistency of less than 5% is deposited on a fabric or mesh 222, forming a web 44 on a table 212, as shown in the drawing. The blade 44 is transferred in the machine direction to the squeezing section 40 and moves to the felt 42 for squeezing. In this case, the fabric is usually dehydrated to a consistency of about 10 to 15% on the mesh 222 before being transferred to the felt. Therefore, the shaft 234 may also be a suction shaft to facilitate transfer to the felt 42. On the felt 42, the web 44 is dehydrated to a consistency of typically about 20 to about 25% before entering the squeezing clamp designated 290. In the clamp 290, the web is pressed onto the cylinder 52 by shaft 242 pressure pads. In this case, the block 244 causes pressure by which the web is transferred to the surface 248 of the shaft 52 with a consistency of from about 40 to 50% on the transfer shaft. The transfer shaft 52 moves in the machine direction, indicated as 284, at a first speed.

The fabric 60 moves in the direction indicated by arrow 286 and engages the web 44 in a creping clamp, indicated as 64. The fabric 60 moves at a second speed that is slower than the first speed of the transfer surface 248 of the shaft 52. Thus, a fabric creped web is typically provided in an amount of from about 10 to about 100% in the machine direction.

The creping fabric defines the creping clip at a distance at which the creping fabric 60 contacts the surface 248 of the shaft 52, i.e. exerts substantial pressure on the web relative to the transfer cylinder. In this regard, the creping shaft 62 may be provided with a soft deformable surface that will increase the width of the creping clip and increase the angle of the fabric creping between the fabric and the sheet at the contact point, or the shaft pressed by the block or the like can be used as the shaft 52 or 62 to increase effective contact with the web in the highly pressed fabric creping clip 64, where the web 44 is transferred to the fabric 60 and advances in the machine direction. Through the use of various equipment in the creping clamp, it is possible to adjust the angle of the fabric creping or the angle of departure of the fabric from the creping clamp. A coating on the shaft 62 having a Pusey and Jones hardness of about 25 to about 90 can be used. Thus, the nature and magnitude of the fiber redistribution, peeling / loosening that can occur in the fabric crepe clamp 64 can be influenced by adjusting these parameters clip. In some embodiments, it may be desirable to rearrange the inter-fiber characteristics in the z-direction, while in other cases it may be desirable to influence the properties only in the plane of the web. The creping hold parameters can affect the fiber distribution in the web in a variety of directions, including z-direction changes, as well as MD and CD. In any case, the transfer from the transfer cylinder to the creping fabric is very tight in that the fabric moves more slowly than the web and a noticeable change in speed occurs. Typically, the web is creped somewhere between 5-60% and even higher during transfer from the transfer cylinder to the fabric.

The creping clip 64 typically extends over a distance or width of the fabric creping clip of anywhere from about 1/8 "to about 2", usually from 1/2 "to 2" (from about 0.3 to about 5.1 cm, usually from 1.3 to 5.1 cm). For a creping fabric with 32 CD strands per inch (12.5 CD strands per centimeter), web 44 will have anywhere from about 4 to 64 weft threads in the clip.

The clamp pressure in clamp 64, i.e., the load between the creping shaft 62 and the transfer shaft 52, is suitably 20-100, preferably 40-70 pounds (acceptable 9-45, preferably 18-32 kg) per linear inch (NLD) (acceptable 3.6-17.9 kg, preferably 7.1-12.5 kg per linear cm (nlcm)).

After fabric creping, the web 44 is retained in the fabric 60 and fed to the drying section 218. In the drying section 218, the web is dried to a consistency of about 92 to 98% before being wound on a reel 276. Note that a plurality of heated drying rolls are provided in the drying section 266, 268 and 270, which are in direct contact with the web on fabric 60. Dryers or shafts 266, 268, and 270 are heated by steam to an elevated temperature capable of drying the web. The shafts 258, 260, 262 and 264 are likewise heated, although these shafts are in direct contact with the fabric and not in direct contact with the web. If necessary, a suction box 66 is provided, which can be used to expand the fabric inside the fabric, increasing the thickness, as described above.

In some embodiments of the invention, it is desirable to eliminate open stretching in a method, such as open stretching between a creping and drying fabric and a spool 276. This is easily achieved by spreading the creping fabric onto the spool drum and transferring the web directly from the cloth to the spool, as described in US Pat. No. 5593545, Rugowski et al .

A preferred creping fabric 60 is shown in FIGS. 7 and 8. FIG. 7 is a grayscale topographic photo of the creping fabric 60, while FIG. 8 is an enlarged two-dimensional topographic color image of the creping fabric shown in FIG. 7. The fabric 60 is installed in the aggregate in FIGS. 4, 5 or 6 in such a way that its MD fists 300, 302, 304, 306, 308, 310 and so on extend along the machine direction of the paper machine. From Figs. 7 and 8, it is evident that fabric 60 is a multilayer fabric having creping pockets 320, 322, 324 and so on between MD fists of the fabric. Also provided are many CD fists 330, 332, 334 and so on, which preferably can be slightly recessed relative to the MD fists of the creping tissue. CD fists can be deepened relative to MD fists by a distance of from about 0.1 mm to about 0.3 mm. This geometry creates a unique fiber distribution when the web is wet cured from the transfer roll, as will be apparent from FIG. 9 and following. Without suggesting to be bound by theory, it is believed that the structure shown with relatively deeply-pockets and limited fist length and height in the CD redistributes the fiber when tightly creped to produce a sheet that is particularly suitable for recycled paper pulp and provides amazing thickness.

9-12 schematically shows a creping clip 64, where the web 44 is transferred from the transfer or return shaft 52 to the creping fabric 60. The fabric 60 has a plurality of warp threads, such as yarns 350, as well as a plurality of weft threads, as can be seen discussed above. The weft threads are located in the first level 352, as well as in the second level 354, as shown in the drawings. The various threads or strands can be of any suitable size, usually the weft strands will have a diameter of 0.50 mm, while the strands of warp will be slightly smaller, possibly 0.35 mm. Warp yarns extend around both levels of weft yarns so that elongated fists, such as fist 300, come into contact with the web located on the transfer shaft 52, as shown in the various drawings. The warp strands may also have smaller fists spaced away from the creping surface, if desired.

In a particularly preferred embodiment, the clamp width at 100 nl (17.9 nlcm) is approximately 34.8 mm when used in conjunction with a creping shaft coating having a P&J hardness of 45. The penetration of the clamp is calculated as 0.49 mm using the Deshpande method. assuming a sleeve thickness of 1 "(2.54 cm). 2" sleeve thickness (5.08 cm) is also acceptable.

A suitable fabric for use according to the present invention is WO-13 fabric, available from Albany International. This fabric provides MD fists having an MD length of approximately 1.7 mm, as shown in FIG. 11.

Without assuming to be bound by theory, it is believed that the creping from the transfer shaft 52 and the redistribution of the paper fiber into the pockets of the creping fabric occurs as shown in Figures 9-12. That is, the trailing edge of the fists contacts the web first where the web bends from the return shaft into the relatively deep creping pockets of the fabric from the return shaft. It should be noted especially FIG. A creping method with a given fabric provides a unique product of the present invention, which is described in connection with FIGS. 13 and 14.

13 and 14 schematically (and photographically) show a pattern with many repeating linear matrices 1, 2, 3, 4, 5, 6, 7, 8 of compressed compressed areas 14 that are oriented in the machine direction. These regions form a repeating pattern 375 corresponding to the MD fists of the fabric 60. For convenience, pattern 375 is shown schematically in FIG. 13 and the lower part of FIG. 14 as arrays of warp 1-8 and weft stripes 1a-8a; the upper part of FIG. 14 is a micrograph of a sheet obtained with this pattern. Pattern 375 thus includes a plurality of machine-oriented (MD) generally elongated, sealed regions of compressed paper fiber 14 having a relatively low local base weight, as well as leading and trailing edges 380, 382, wherein the densified regions are located in a repeating pattern of a plurality of generally parallel linear arrays 1-8 that are staggered longitudinally staggered relative to each other, so that a plurality of intermediate linear arrays is located between a pair of CD-aligned arrays tnennyh regions 384, 386. There are a plurality of fiber enriched, pileate regions 12 having relatively high local basis weight regions dispersed between the sealed and connected with them, wherein shlyapochnye areas have ridges extending side CD. In general, parallel, longitudinal arrays of densified regions 14 are arranged and configured such that a fiber-rich region 12 between a pair of CD-aligned densified regions extends to the CD without being obstructed by the front or rear edges 380, 382 of the densified regions of the at least one intermediate linear array. As shown, generally parallel, longitudinal arrays of densified regions are arranged and configured such that the fiber-enriched region 12 between a pair of CD-aligned densified regions 14 extends into the CD without being obstructed by the front or rear edges of the densified regions of the at least two intermediate linear arrays. Therefore, the fiber-rich region 12 between the pair of CD-aligned densified regions 384, 386 is at least partially truncated and at least partially bounded in MD by the front or rear edges of the densified regions of at least one or two intermediate linear sheet arrays in the MD position 388 , intermediate MD positions 380, 390 of the front and rear edges of the CD-aligned densified areas. The front and back MD edges of the fiber-enriched cap areas are generally concave inward, so that the central MD portion 396 of the fiber-rich areas is smaller than the MD portion 398 at the lateral ends of the fiber-rich areas. Elongated densified areas occupy from about 5% to about 30% of the sheet area and are estimated as corresponding to the area MD of the fists of the tissue used. The cap areas occupy from about 95% to about 50% of the leaf area and are estimated using reduced tissue areas. In the embodiment shown in FIGS. 13 and 14, the distance 400 between the CD-aligned densified regions is 4.41 mm, so that the linear arrays of the densified regions have a repetition rate MD of approximately 225 meter ⁻¹ . The densified elements of the arrays are spaced at a distance of 402 of approximately 8.8 mm, thus having a repetition rate MD of approximately 110 meter ^-1 .

The fiber-rich regions have a vaulted structure, where the crests of the cap regions form arches around the front and rear edges of the densified regions, as can be seen, in particular, in the upper part of FIG.

The product thus has the features shown and described above in connection with FIGS. 1 and 2.

Additional aspects of the invention are apparent from FIGS. 15-30. Fig is a micrograph of the canvas, similar to the micrograph shown in figure 2, where the canvas was stretched in the machine direction. It can be seen here that the cap region 12 is expanded to a much greater degree of porosity, increasing the absorbency of the sheet.

FIG. 16 is a photomicrograph of a base sheet similar to the sheet shown in FIG. 1, indicating a section shown in FIG. 17. 17 is a cross-sectional view of a bonded fiber-rich region where it can be seen that the macro folds were not fist-tightened. On Fig shows that this sheet has distinct sides. If it is desired to reduce this severity, the web can be transferred to another surface during drying, so that the fabric side of the web (before transfer) is in contact with the drying drums after that.

Fig. 18 is an enlarged micrograph showing an MD fingerprint of a creping tissue, where it is seen that the fiber of the sealed MD region has an inclination of the CD orientation and that the fiber-enriched cap regions have a vaulted structure around the MD propagating, sealed region.

The change in the local base weight of the sheet is shown in Figs. 19 and 20. Figs. 19 and 20 are X-ray negatives of the absorbent sheet of the present invention, where the light areas reflect areas of high base weight and the darker areas represent areas with a relatively lower base weight. These pictures were taken by placing sheet samples on plates and exposing these samples to an 6 kW x-ray source for 1 hour. Fig. 19 is an X-ray taken without suction, while Fig. 20 was obtained by applying suction to the sheet.

In both FIGS. 19 and 20, it is seen that there are many dark, MD propagating regions with a relatively low base weight corresponding to the MD tissue fists in FIG. 7. Lighter and whiter areas show fiber-enriched areas with a relatively high base weight. These regions propagate in the CD along the folds shown in FIG. 18, for example.

Figs. 19 and 20 prove the local base weight change seen in SEM and other micrographs, especially the relatively rectangular relationship between areas with low base weights and areas with high base weights.

Note that FIG. 19 with suction turned off shows a slightly stronger change in base weight (more visible light areas) than FIG. 20 with suction turned on, consistent with FIGS. 22 and 23, discussed below.

Additional product options are visible on figa-21D. Figa and 21B, respectively, are micrographs of the fabric side and the Yankee side of the sheet with 25 pounds of base weight (41 g / m ² ) with a tissue creping ratio of 1.3. 21C and 21D are micrographs of another sheet with a 25 pound base weight obtained with a tissue creping ratio of 1.3. Where suction is indicated in the captions of the figures, that is, the sheet in FIGS. 21C, 21D was subjected to suction stretching after tissue creping.

Figures 22 and 23 show the effect of absorption in the manufacture of the sheet of the present invention. FIG. 22 is a micrograph along an MD of a pulp sheet obtained according to the present invention, with a Yankee side up, obtained without suction. 23 is a micrograph of a cellulosic sheet made according to the present invention when the suction box 66 has been turned on. From these figures it can be seen that absorption increases the volume (and absorbency) of the sheet. On Fig it is seen that there are micro folds included in the macro folds of the sheet. 23, the micro-folds are no longer visible. For comparison purposes, FIG. 24 shows a corresponding sectional view along the machine direction CWP of the base sheet. It can be seen here that the fiber is relatively dense and does not exhibit an increased and uniform volume of the products of this invention.

Beta Attenuation Analysis

To quantify the change in local base weight, beta particle attenuation technology was used.

Beta particles are produced when an unstable nucleus with too many protons or neutrons decays spontaneously, giving a more stable element. This process can produce positive or negative particles. When a radioactive element with too many protons undergoes beta decay, the proton turns into a neutron, emitting a positively charged beta particle or positron ( β ⁺ ) and neutrino. In contrast, a radioactive element with too many neutrons undergoes beta decay by converting a neutron into a proton, emitting a negatively charged beta particle or electron ( β ^- ) and antineutrino. Promethium ( ¹⁴⁷ ₆₁ Pm ) undergoes negative beta decay.

The beta measurement is based on a method of counting the number of beta particles that pass through a sample and fall into a detector located opposite the source for the same period of time. Beta particle paths deviate widely when they interact with matter; some remain inside it, others pass through or dissipate after a partial loss of energy and eventually leave the substance with a wide range of angles.

Anderson, DW (1984) Absorption of Ionizing Radiation , Baltimore, University Park Press, (pp.69) states that for average transmittances, transmittance can be calculated as follows:

I = i ₀ e ^-βρt  = I ₀ e ^-βw

where I ₀ denotes the intensity of the radiation incident on the material;

β denotes the mass coefficient of effective beta absorption in cm ² / g;

t denotes a thickness in cm;

ρ is the density in g / cm ³ ;

w denotes the base weight in g / cm ² .

A stand-alone profilometer equipped with an AT-100 radioisotope sensor (Adaptive Technologies, Inc., Fredrick, MD) containing 1800 micrometres of promethium was calibrated using a polycarbonate collimator having an aperture of approximately 18 mils (0.46 mm) in diameter. Calibration was performed by placing the collimator on top of the beta particle source and measuring the counts for 20 seconds. The operation was repeated with 0, 1, 2, 3, 4, 5, 6, 7, 8 layers of a film of polyethylene terephthalate having a base weight of 10.33 pounds / 3000 ft ² feet (16.8 g / m ² ). The results are given in Table 1 and graphically presented in Fig.25.

Table 1
Calibration Counting Weight lbs / 3000 ft ² Weight (g / m ²⁾ 165.3 0 0 114.4 10.33 16.81 80.9 20.68 33.65 62.3 30.97 50.40 43.3 41.3 67.21 33 51.63 84.02 26.2 61.93 100.78 17.1 72.28 117.62 15,2 82.61 134.43 eleven 92.9 151.17

The calibrated apparatus was then used to measure the local base weight in the sample of the absorbent sheet, usually having the structure shown in Fig. 18. Base weight measurements were usually made at positions 1-9, schematically indicated in FIG. The results are given in Table 2.

table 2
Change in local base weight Position Count Calculated Base Weight The calculated base weight (g / m ² ) one 60 32.38 52.70 2 73.8 25.24 41.08 3 76.6 23.96 38,99 four 71.2 26.48 43.09 5 66.3 28.94 47.09 6 37.5 48.59 79.08 7 55.8 34.89 56.77 8 60,4 32.16 52.33 9 59.9 32,44 52.79

It can be seen from the above that the local base weight at position 6 (fiber enriched area) is much higher, 50% or so, than at position 2 of the low base weight area. The local base weight at position 1 between the folds was correspondingly relatively low; however, the local base weights at positions 4 and 7 were slightly higher than expected, possibly due to the presence of wrinkles in the sample that occurred during fabric or winding creping.

The proposed products and the method of their manufacture are extremely useful for a wide variety of products. For example, FIG. 27 shows a comparison of tested softness for various products of two-ply bathroom fabrics.

Product 2005 was made from a single layer fabric, while product 2006 was made from a multilayer fabric of the present invention. Note that products made from multilayer fabrics showed much greater softness at a given stretch. These data are also shown in FIG.

Details on the various tissue products are summarized in Tables 3, 4 and 5. Fabric 44M is a single-layer fabric, while fabric W013 is a multi-layer fabric, discussed in connection with FIG. 7 and subsequent.

Table 3
Comparison of the base sheet and the properties of the final products the cloth 2005 2006 44M (MD) W013 (MD) Fiber 75% euc 60% euc Molding Mixed Smesh. and Fr. Softener 1152.2 # 1152.4 # Fabric Crepe from 25 to 35 from 17 to 32 Suction from 12 to 22 23 BS thickness without suction 63 90 BS thickness with maximum absorption 79 115 FP BW from 27 to 29 32 FP thickness from 133 to 146 from 180 to 200 FP GMT from 500 to 580 460 to 760 FP softener from 18.8 to 19.4 from 19.4 to 20.2

Table 4
Property Comparison (2-ply) the cloth 2005 2006 44M W013 BS thickness without suction 63 90 BS thickness with maximum absorption 79 115 FP BW from 27 to 29 32 FP thickness from 133 to 146 from 180 to 200 FP softener from 18.8 to 19.4 from 19.4 to 20.2

Table 5
Comparison of final products and SHS product the cloth 2005 2006 TAD commercial 44M W013 FP GMT 600 600 600 FP softener 18.9 20.1 20,2 FP thickness 145 171 151 Sheet counting 200 200 200 Shaft diameter 4.70 4.90 4.75 Shaft hardness 17.7 9.3 17.6

Table 6
Comparison of the base sheet and the properties of the final products for 44M / MD and W013 fabrics Item ID: base sheet P2150 11031/11032 type of product QNBT Ultra QNBT Ultra Paper pulp 75/25 Euc / Mar 60/40 Euc / Mar eTAD fabric / side up 44M / MD W013 % Fabric crepe /% reel crepe 25/2 31.5 / 8.5% Suction twenty 23.1 Base Weight lbs / stop g / m ² ) 16.42 (26.72) 17.60 (28.64) Thickness (mil / 8 sheets) (mm / 8 sheets) 79.7 (2.02) 121.4 (3.08) MD extensibility (g / 3 ") (g / cm) 474 (62.2) 569 (74.7) CD extensibility (g / 3 ") (g / cm) 231 (30.3) 347 (45.5) Item ID: base sheet P2150 11031/11032 GM elongation g / 3 "(g / cm) 330 (43.3) 444 (58.3) MD stretch (%) 28.8 51.5 CD pull (%) 7.9 9.6 CD wet extensibility - Finch g / 3 "(g / cm) 27 (3.5) 0 (0) GM burst modulus (g /%) 21.9 20,0 Base sheet volume in mil / 8 layers / lb / R ((mm / 8 layers) / (g / m ² )) 4.85 (0.075) 6.90 (0.11) Stamping pattern HVS9 high elements double hearts Rubber return shaft 55 Shore A 90 P&J Sheet counting 176 198 Base Weight lbs / stop (g / m ² ) 30.6 (49.8) 29.5 (48.0) Thickness mil / 8 sheets (mm / 8 sheets) 150.2 (3.81) 170.8 (4.34) MD dry extensibility g / 3 "(g / cm) 478 (62.7) 695 (91.2) CD dry extensibility g / 3 "(g / cm) 297 (39.0) 451 (59.2) Geometric average tensile g / 3 "(g / cm) 376 (49.3) 559 (73.4) MD stretch (%) 12.0 28.7 CD pull (%) 7.2 9.1 Tensile perforation g / 3 "(g / cm) 258 (33.9) 393 (51.6) CD wet extensibility g / 3 "(g / cm) 42.2 (5.54) 10 (1.31) GM burst modulus (g /%) 40.5 35.0 Friction (GMMMD) 0.546 0.586 Shaft Diameter Inches (cm) 4.67 (11.9) 4.91 (12.5) Shaft compression (%) 23.7 9.3 Felt soft 19.61 20,2 The volume of the final product in mil / 8 layers / lb / R ((mm / 8 layers) / (g / m ² )) 4.91 (0.077) 5.78 (0.090)

From Tables 3 to 5 it can be seen that the method and products of the present invention, made with a multilayer fabric, provide much greater thickness at a given base weight, as well as increased softness.

Table 6 above also shows that the fabric products of the present invention made with W0-13 fabric exhibit much greater softness with even higher tensile strength, a very surprising result, as common sense makes it clear that softness decreases rapidly with increasing strength by the gap.

The present invention also provides a unique combination of properties for the manufacture of single-layer towels and makes it possible to use increased amounts of recycled fiber without adversely affecting product performance or tactile properties. In this regard, paper pulp mixtures containing recycled fiber were evaluated. The results are summarized in Tables 7, 8 and 9.

Table 8
Base sheet data ID BW lbs / stop {g / m ² } Unc.Cal. mil / 8 layers {mm / 8 layers} Cal. Cal.Mil / 8 layers {mm / 8 layers} MDS (%) MD dry g / 3 "{g / cm} SofPull Target (min / max) 21.3 (20.6 / 22) {34.7 (33.5 / 35.8} 78.0 (72, / 84) {1.98 (1.83 / 2.13)} 23.0 (18/28) 2.750 (2300/3200) {361 (302/420) Element 1 21.1 {34.3} 95 {2.41} 77 {1.96} 24.4 2,468 {324} Element 2 21.2 {34.5} 84 {2,13} 78 {1.98} 24.1 2,669 {350} Element 2A 20.6 {33.5} 95 {2.41} 76 {1.93} 25.5 2,254 {296} Element 3 21.4 {34.8} 88 {2.23} 79 {2,00} 26.2 2,867 {376} Element 4 21.4 {34.8} 88 {2.23} 76 {1.93} 27.6 2,787 {366} Table 8
Continuation ID CD dry g / 3 "{g / cm} GMT Full g / 3 "{g / cm} The ratio of MD / CD CD wet g / 3 "{g / cm} WAR (sec) SofPull Target (min / max) 1,900 (1450/2550) {249 (190/335) 2,286 4,650 1.4 450 (min 325) {59 (min 43) 5.0 (max 15) Element 1 1,908 {250] 2,170 4,376 {574} 1.3 445 {58} four Element 2 1,924 {253} 2,266 4,593 {603} 1.4 426 {56} 6 Element 2A 1,761 {231} 1,992 4.015 {527} 1.3 385 {51} 5 Element 3 1,793 {235} 2,267 4,660 {612} 1,6 462 {61} 5 Element 4 1,974 {259} 2,346 4,761 {625} 1.4 505 {66} 5

A significant increase in thickness is seen in FIG. 29, which shows that the base sheets obtained with multilayer fabric exhibit increased thickness relative to the base sheets obtained with single-layer creping fabrics. The amazing volume is clearly visible when comparing these products with TAD products or products made with single-layer fabric. 30A-30F show various base sheets. FIGS. 30A and 30D, respectively, are micrographs of the Yankee side and the tissue side of a base sheet obtained with a single layer fabric obtained according to the method described above in connection with FIG. FIGS. 30B and 30E are micrographs of the Yankee side and the fabric side of a warp sheet obtained with a two-layer creping fabric according to this invention using the method described generally in connection with FIG. 5 above. 30C and 30F are micrographs of the Yankee side and the tissue side of a base sheet obtained using the conventional TAD method. From the micrographs in FIGS. 30B and 30E, it can be seen that the base sheet of the present invention obtained with a two-layer fabric gives a higher elongation than other materials shown in FIGS. 30A, D, C and F. This observation is consistent with FIG. which shows the relative softness of the products in FIG. 30A and FIG. 30D (single layer fabric) and other products made with increased levels of reusable fiber according to this invention. From Fig. 31 it can be seen that it is possible to obtain a towel base sheet with equivalent softness using up to 50% recycled fiber. This is a significant advantage, since towels can be produced without the use of expensive paper pulp from natural Douglas fir, for example.

The products and method of the present invention are thus likewise suitable for use with the non-contact automatic towel dispensers of the class described in simultaneously contemplated US Provisional Application No. 60/779614, filed March 6, 2006, and US provisional Application No. 60/693699 filed June 24, 2005, descriptions of which are incorporated herein by reference. In this regard, this base sheet is suitably prepared on a paper machine of the class shown in FIG. 32.

FIG. 32 is a schematic view of a paper machine 410 having a conventional double-mesh forming section 412, belt mileage 414, pad compression section 416, creping fabric 60, and Yankee cylinder 420 suitable for practicing the present invention. The forming section 412 includes a pair of forming fabrics 422, 424 supported by a plurality of shafts 426, 428, 430, 432, 434, 436 and a forming shaft 438. A pressure box 440 provides paper pulp that flows in a machine direction into a press clip 442 between forming shaft 438 and shaft 426, and fabrics. The paper pulp forms a nascent web 444, which is dehydrated on these tissues by suction, for example, by means of a suction box 446.

The nascent web advances onto the paper machine belt 42, which is supported by a plurality of shafts 450, 452, 454, 455, and the belt is in contact with the press pad shaft 456. This fabric has a low consistency when transferred to the belt. The transfer can be assisted by suction, for example, the shaft 450 can be a suction shaft, if necessary, or a gripper or suction pad can be used, as is known in the art. When the web reaches a pressable shaft block, it can have a consistency of 10-25%, preferably from 20 to 25% or so, when it enters the clip 458 between the pressure block shaft 456 and the transfer shaft 52. The transfer shaft 52 may be a heated shaft, if necessary. It has been found that increasing the vapor pressure on the shaft 52 helps to increase the time between the required removal of excess adhesive from the cylinder of the Yankee dryer 420. A suitable steam pressure may be approximately 95 psig or so, given that the shaft 52 is a convex shaft and the shaft 62 has a concave profile, opposed in such a way that the contact area between the shafts depends on the pressure in the shaft 52. Thus, care must be taken to maintain proper contact between the shafts 52, 62 when increased pressure is applied.

Instead of the shaft pressed by the block, the shaft 456 may be a conventional shaft with suction pressure. If shoe pressing is used, it is desirable and preferable that the shaft 454 is a suction shaft effective to remove water from the tape before the tape enters the clip pressed by the block, since water from the paper pulp will be pressed into the tape in the pressed block. In any case, the use of a suction shaft at 454 is usually desirable to ensure that the web remains in contact with the tape during a change of direction, as will be seen from the drawing by a person skilled in the art.

The web 444 is wet-squeezed on the tape in the clamp 458 using a pressure pad 50. The web is thus dehydrated by squeezing at 458, usually by increasing the consistency by 15 or more units at this stage of the process. The configuration shown at 458 is commonly referred to as block compression; in connection with the present invention, cylinder 52 functions as a transfer cylinder that operates by transferring the web 444 at a high speed, typically 1000 f / min to 6000 f / min (305 m / min to 1830 m / min), onto the creping fabric.

The cylinder 52 has a smooth surface 464 that can be provided with an adhesive (the same as creping adhesive used on a Yankee cylinder) and / or release agents, if desired. The web 444 adheres to the transfer surface 464 of the cylinder 52, which rotates at a high angular speed, so that the web continues to advance in the machine direction indicated by arrows 466. On this cylinder, the web 444 has a generally random apparent distribution of fiber orientation.

Direction 466 is called the machine direction (MD) of the web, as well as the direction of the paper machine 410; the transverse direction (CD) is the direction in the plane of the web, perpendicular to MD.

The canvas 444 enters the clamp 458 at a consistency of 10-25% or about, and is dehydrated and dried to a consistency of from about 25 to about 70 during the time during which it is transferred to the creping fabric 60, as shown in the drawing.

The fabric 60 is supported by a plurality of shafts 468, 472 and a squeezing clip 474 and forms a fabric creping clip 64 with a transfer cylinder 52, as shown.

The creping fabric defines the creping clip at a distance where the creping fabric 60 is in contact with the shaft 52, i.e., applying substantial pressure to the web relative to the transfer cylinder. For this, the creping shaft 62 can be provided with a soft deformable surface that will increase the width of the creping clip and increase the angle of tissue creping between the fabric and the sheet and the contact point, or the shaft pressed by the block can be used as the shaft 62 to increase effective contact with the web in close clamp 64 of fabric creping, when web 444 is transferred to fabric 60 and advances in the machine direction.

The creping clip 64 typically extends over a distance or width of the fabric creping clip in the range of from about 1/8 "to about 2", usually from 1/2 "to 2" (from about 0.3 to about 5.1 cm, usually from 1 , 3 to 5.1 cm). For creping fabric with 32 CD strands per inch (12.5 CD strands per centimeter), web 444 will thus provide from about 4 to about 64 strands of weft in the clip.

The clamping pressure in clamp 64, i.e., the load between the creping shaft 62 and the transfer shaft 52, is suitably 20-200 (9-91 kg), preferably 40-70 pounds (18-32 kg) per linear inch (PLI) (suitable 3.6-36 kg, preferably 7-13 kg per linear cm (plcm)).

After fabric creping, the web continues to advance along MD 466, where it is wet pressed onto the Yankee cylinder 480 in the transfer clip 482. If necessary, suction is applied to the web through the suction box 66.

The transfer in clip 482 occurs with a web consistency of from about 25 to about 70%. With this consistency, the web is difficult to adhere to the surface 484 of the cylinder 480 firmly enough to carefully remove the web from the fabric. This aspect of the method is important, in particular, when it is desirable to use a casing for high-speed drying.

The use of special adhesives helps a moderately moist cloth (consistency of 25-70%) adhere to the Yankee cylinder sufficiently to allow high-speed operation of this system and high-speed forced jet air drying and subsequent peeling of the cloth from the Yankee cylinder. In this regard, the adhesive composition polyvinyl alcohol / polyamide, as described above, is applied to 486, preferably at a value of less than about 40 mg / m ² sheet. Accumulation is regulated as described below.

The canvas is dried on a Yankee cylinder 480, which is a heated cylinder, and using a high-speed jet of forced air in the Yankee casing 488. The casing 488 may have a variable temperature. During operation, the temperature can be continuously monitored at the wet end A of the casing and the dry end B of the casing using an infrared detector or any other suitable means if necessary. When the cylinder rotates, the web 444 peels off from the cylinder at 489 and is wound on a tension reel 490. Coil 490 can operate at 5-30 f / min or 1.5-9.1 m / min (preferably 10-20 f / min; 3- 6 m / min) is faster than a Yankee cylinder in a stationary state when the line speed is 2100 f / min (640.5 m / min), for example. A creping scraper C is typically used, and a cleaning scraper D mounted for intermittent insertion is used to control layering. When the adhesive lamination is removed from the Yankee cylinder 480, preferably by feeding to the discharge at 500 for reuse in the production method, the web is usually separated from this product on a reel 490.

Instead of winding from a cylinder 480 at 489 during stationary operation, as shown, the web can be creped from the drying cylinder 480 using a creping scraper, such as creping scraper C, if desired.

Using the above procedures, a range of “wound” towel products were prepared using fabric W013. The process parameters and product features are shown in Tables 10, 11 and 12 below.

Table 10
Single Layer Towel Sheet Shaft ID 11429 11418 11441 11405 11137 NSWK one hundred% fifty% one hundred% fifty% Reusable Fiber fifty% fifty% one hundred% % fabric creping 5% 5% 5% 5% 5% Suction inches Hg (cm Hg) 23 (58) 23 (58) 23 (58) 23 (58) 23 (58) WSR (# / T) 12 12 12 12 12 CMC (# / T) 3 one 2 one one Parez 631 (# / T) 9 6 9 3 0 PVOH (# / T) 0.75 0.75 0.750.75 0.75 0.45 PAE (# / T) 0.25 0.25 0.25 0.25 0.15 Modifier (# / T) 0.25 0.25 0.25 0.25 0.15 Yankee cylinder speed, f / min (m / min) 1599 (488) 1768 (539) 1599 (488) 1598 (487) 1598 (487) Base Weight, lbs / stop (g / m ² ) 18.4 (29.9) 18.8 (30.6) 21.1 (34.3) 21.0 (34.2) 20.3 (33.0) Winding speed f / min (m / min) 1609 (491) 1781 (543) 1609 (491) 1612 (492) 1605 (490) Thickness, mil / 8 sheets (mm / 8 sheets) 41 (1.04) 44 (1.12) 44 (1.12) 45 (1.14) 44 (1.12) Dry MD extensibility, g / 3 "(g / cm) 4861 (638) 5517 (724) 6392 (839) 6147 (807) 7792 (1022) Dry CD tensile, g / 3 "(g / cm) 3333 (437) 3983 (523) 3,743 (491) 3707 (487) 4359 (572) GMT g / 3 "(g / cm) 4025 (528) 4688 (615) 4891 (642) 4773 (626) 5828 (764) MD stretch (%) 6.9 6.6 7.2 6.2 6.4 CD pull (%) 5,0 5,0 4.8 5,0 4.9 MD wet gap, g / 3 "(Finch) {g / cm} 1441 {189} 1447 {190} 1644 {216} 1571 {207} 2791 {366} CD gap in the wet state, g / 3 "(Finch) {g / cm} 1074 {141} 1073 {141} 1029 {135} 1064 {140} 1257 {165} WAR (seconds) (TARPI) 33 32 twenty twenty 39 MacBeth 3100 L * UV Included 95.3 95.2 95.2 95.4 95.4 MacBeth 3100 A * UV On -0.8 -0.4 -0.8 -0.3 0,0 MacBeth 3100 * UV included 6.2 3,5 6.2 3.3 1,1 MacBeth 3100 V brightness (%) UV included 80.6 83.5 80.3 84.3 87.1 GM burst module 691 817 831 858 1033 Sheet Width, inches (cm) 7.9 (20.1) 7.9 (20.1) 7.9 (20.1) 7.9 (20.1) 7.9 (20.1) Shaft Diameter Inches (cm) 7.8 (19.8) 7.9 (20.1) 8.0 (20.3) 7.9 (20.1) 8.1 (20.6) Shaft compression (%) 1.3 1.3 1,2 1,1 1,1 AVE bending length (cm) 3,7 3.9 4.0 4.1 4.7

Table 11
Single layer towel Shaft ID 89460 89460 89460 89460 89460 goal Max. Min 11443 11414 11437 11396 11137 NSWK one hundred% fifty% one hundred% fifty% Reusable Fiber fifty% fifty% one hundred% Parez 631 (# / T) 9 6 9 3 0 PVOH (# / T) 0.75 0.75 0.75 0.75 0.45 PAE (# / T) 0.25 0.25 0.25 0.25 0.15 Modifier (# / T) 0.25 0.25 0.25 0.25 0.15 Base Weight, lbs / stop (g / m ² ) 18.4 (29.9) 18.4 (29.9) 21.1 (34.3) 20.9 (34.0) 20.0 (32.5) 20.8 (33.8) 22.0 (35.8) 19.6 (19.6) Thickness, mil / 8 sheets (mm / 8 sheets) 48 (1.22) 52 (1.32) 49 (1.24) 53 (1.35) 47 (1.19) 50 (1.27) 55 (1.40) 45 (1.14) Dry MD extensibility, g / 3 "(g / cm) 5050 (663) 5374 (705) 6470 (849) 6345 (833) 7814 (1026) 6500 (853) 8000 (1050) 5000 (656) Dry CD tensile, g / 3 "(g / cm) 3678 (483) 3928 (515) 3869 (508) 3817 (501) 4314 (566) 4000 (525) 5000 (656) 3000 (394) MD stretch (%) 7.0 7.5 7.2 7.4 7.0 6 8 four CD pull (%) 4.9 5.2 4.8 5.2 4.9 MD stretch (%) 7.0 7.5 7.2 7.4 7.0 6 8 four CD pull (%) 4.9 5.2 4.8 5.2 4.9 MD wet gap, g / 3 "(Finch) {g / cm} 1711 {225} 1557 {204} 1888 {248} 1851 {243} 2258 {296} CD wet gap Cured elongation, g / 3 "(Finch) {g / cm} 1105 {145} 1086 {142} 1005 {132} 1163 {153} 1115 {146} 900 {118} 1250 {164} 625 {82} WAR (seconds) (TARPI) 43 29th 26 23 34 eighteen 35 one MacBeth 3100 L * UV Included 95.1 95.1 95.0 95.2 95.5 MacBeth 3100 A * UV On -0.9 -0.4 -0.8 -0.4 -0.3 MacBeth 3100 * UV included 6.2 3.6 6.1 3.3 1.4 MacBeth 3100 brightness (%) UV on 80 83 80 84 87 GM burst module 737 734 853 793 991 Shaft Diameter Inches (cm) 7.9 (20.1) 8.0 (20.3) 8.0 (20.3) 8.1 (20.6) 8.0 (20.3) 8.0 (20.3) 7.8 (19.8) 8.2 (20.8) AVE bending length (cm) 4.0 4.0 4.2 4.1 4.8 4,5 5.3 3,7

Table 12
Single Layer Towel Sheet Shaft ID Base sheet Base sheet Base sheet 11171 9691 9806 NSWK one hundred% one hundred% one hundred% the cloth Prolux W13 36g 44g % fabric creping 5% 5% 5% Cleaning (amps) 48 43 44 Suction (Hg) 23 19 23 WSR (# / T) 13 13 eleven CMC (# / T) 2 one one Parez 631 (# / T) 0 0 0 PVOH (# / T) 0.45 0.75 0.75 PAE (# / T) 0.15 0.25 0.25 Modifier (# / T) 0.15 0.25 0.25 Yankee cylinder speed, f / min (m / min) 1599 (488) 1749 (533) 1749 (533) Winding speed f / min (m / min) 1606 (490) 1760 (537) 1760 (537) Yankee Cylinder Steam, psi (bar) 45 (3.1) 45 (3.1) 45 (3.1) Humidity% 2.5 4.0 2.6 Thickness, mil / 8 sheets (mm / 8 sheets) 60.2 (1.53) 50.4 (1.28) 51.7 (1.31) Base Weight, lbs / 3000 ft ² (g / m ² ) 20.9 (34.0) 20.6 (33.5) 20.8 (33.8) MD Tensile, g / 3 "(g / cm) 6543 (859) 5973 (784) 6191 (813) MD stretch (%) 6 7 7 CD extensibility, g / 3 "(g / cm) 3787 (497) 3963 (520) 3,779 (496) CD stretching (%) 4.4 4.1 4.3 Wet gap according to Finch Cured-MD method, g / 3 "(g / cm) 1097 (144) 1199 (157) 1002 (132) GM extensibility, g / 3 "(g / cm) 4976 (653) 4864 (638) 4836 (634) Abs. water speed, 0.1 ml / s twenty 22 twenty GM rupture module, gms /% 973 913 894 Dry elongation ratio 1.7 1,5 1,6 Full dry extensibility, g / 3 "(g / cm) 10331 (1356) 9936 (1304) 9970 (1308) Wet / Dry Tensile CD 29% thirty% 27% Hanging Dwn - MD SMS 9.8 7.6 8.0 Bending length MD, yank-cylinder down, cm 4.9 3.8 4.0 Bending length MD, Yankee cylinder up, cm 5,0 4.8 9.0 Overhang, Yankee Cylinder Up - MD SMS 9.9 9.6 4,5 AVE bending length - MD (cm) 4.9 4.3 4.2

Note that again, the present invention makes it possible to use elevated levels of recycled fiber in towels without compromising product quality. Also, a reduced amount of addition of Yankee coatings was preferred when using 100% recycled fiber. The addition of recycled fiber also reduces the use of resin for dry strength.

FIGS. 33 and 34 show that the high bending length MD of the product obtained in the aggregate according to FIG. 32 was observed at relatively high levels of wet CD tensile strength and surprisingly elevated thickness levels.

Reel crepe

The multilayer fabric shown and described in connection with FIGS. 7 and 8 can provide very strong winding creping with many products. This feature makes possible the flexibility of production and more efficient operation of the paper machine, since greater thickness can be achieved with this in-line creping, and / or the speed at the wet end (production bottleneck for many machines) can be more fully used, as will be seen from the discussion that follows. .

Winding creping examples

The base sheets of towels were made from paper pulp, consisting of 100% kraft pulp of southern softwood. All base sheets were made with the same target base weight (15 pounds / 3000 ft ² feet; 24.4 g / m ² ), tensile strength (1400 g / 3 inch geometric mean tensile; 184 g / cm geometric mean tensile) and ratio stretching (1.0). The base sheets were creped using several fabrics. For single-layer fabrics, the sheets were creped using both sides of the fabric. The labels “MD” or “CD” in the fabric designation indicate whether the fists were in the machine direction or the transverse direction of the fabric in contact with the base sheet. The aim of the experiment was to determine the level of tissue creping, beyond which an increase in the thickness of the base sheet would not be obtained.

For each fabric, the base sheets were made for the above purposes at the selected level of fabric creping without winding creping. The fabric creping was then increased in increments of five percent, and the cleaning and the jet / mesh ratio were adjusted as necessary to obtain the target sheet parameters again. This method was repeated until the increase in tissue creping did not increase the thickness of the base sheet or until the limits of practical implementation were reached.

The results of these experiments are shown in Fig. 35. These data show that at 0% winding creping, the thickness obtained using W013 fabric can be equal to or several times exceeded by several single-layer fabrics.

For several fabrics, tests were also performed in which winding creping, in addition to fabric creping, was used to achieve a desired thickness level of approximately 95 mils / 8 sheets (2.41 mm / 8 sheets). The results of these tests are shown in Table 13. The designations "TK" and "NK" indicate the levels of fabric creping and winding creping, respectively, used to obtain these base sheets.

The test results show that for single-layer fabrics (“M” and “G” fabrics) the thickness increments with the addition of winding creping were all approximately one mil / 8 sheets of thickness for each percent of winding creping used. However, the increase in thickness with the addition of winding creping observed for W013 fabric was much higher; the ratio of the increase in thickness /% winding craigrownie, equal to 3, was easily achieved. In other words, instead of an increase of 1 unit of thickness per 1 unit of winding creping, an increase of 3 units of thickness per unit of winding creping used in this method was achieved when using fabric with long MD fists.

Table 13
The effect of winding creping on the thickness of the base sheet. All thickness values are normalized to a base weight of 15 lbs / stop (24.4 g / m ² ) the cloth 44G CD 36G CD 36G CD 44M MD 36M MD W013 TK / NK (%) 30/0 40/0 30/0 40/0 30/0 25/0 Inline creping (%) thirty 40 thirty 40 thirty 25 Thickness mil / 8 sheets (mm / 8 sheets) 92.4 (2.34) 94.1 (2.39) 91.5 (2.32) 80.9 (2.05) 79.7 (2.02) 83.3 (2.12) TK / NK (%) 30/5 40/2 30/5 40/12 30/15 25/7 Inline creping (%) 36.5 42.8 36.5 56.8 49.5 33.75 Thickness mil / 8 sheets (mm / 8 sheets) 95.2 (2.42) 96.0 (2.44) 96.5 (2.45) 93.6 (2.38) 97.3 (2.47) 103.2 (2.62) Thickness gain /% winding creping ratio 0.6 1,0 1,0 1,1 1,2 2,8

With fabric W013, fabric creping can be reduced by a factor of 3, since winding creping still retains thickness. For example, if the method operates, reaching a thickness of 100 with W013 fabric at a 1.35 ratio of total creping (30% of fabric creping and 4% of winding creping for 35% of total creping) and it is desirable to increase the tensile ability while maintaining the thickness, you can do the following: reduce tissue creping up to 21% (the extensibility will probably increase) and then increase winding creping by 7% for a total ratio of 1.295 or 29.5% of the total creping, thereby obtaining greater stretch and maintaining thickness (m less creping and much less fabric creping, which is thought to be more destructive to extensibility than reeling creping).

In addition to better regulation of thickness and elongation, the paper machine can be made much more productive. For example, for a 15 lb (24.5 g / m ² ) towel base sheet, 57% in-line creping with 44M fabric for a final thickness of 94 was required. W013 multilayer fabric gave a thickness of 103 at about 34% in-line creping. Using these approximate values, a paper machine with a speed limit at the wet end of 6000 f / min (1830 m / min) will have a speed limit of 3825 f / min (1167 m / min) when winding to obtain a target thickness of 94 for the base sheet with fabric 44M. However, the use of W013 fabric can produce approximately 10 units of thickness, which will speed up winding up to 4475 (6000 / 1.34 versus 6000 / 1.57) f / min (1365 m / min).

In addition, a multi-layer fabric with long MD fists can reduce the base weight and maintain thickness and extensibility. Smaller fabric creping will require less cleaning in order to obtain the required elongation, even with a given inline creping (again assuming that winding creping is much less destructive for extensibility than fabric creping). As the weight of the product goes down, fabric creping can be reduced by 3 percent for every percent increase in winding creping, making it easier to maintain thickness and maintain extensibility.

The effect of winding creping in Table 13 is confirmed in microphotographs in FIGS. 36-38, which are taken along MD (samples 60 microns thick) fabric-creped sheet. Fig. 36 shows a web with 25% fabric creping and without winding creping. Fig. 37 depicts a web made with 25% winding creping and 7% fabric creping, where it can be seen that this creping is much more noticeable than in Fig. 36. Fig. 38 depicts a web with 35% fabric creping and without winding creping. The canvas in FIG. 37 appears to be noticeably more creped than the canvas in FIG. 38, although it was made with approximately the same inline creping.

In many cases, the fabric creping techniques described in subsequent co-pending applications will be particularly suitable for the manufacture of products: US Patent Application Serial No. 11/678669, entitled “Method for Regulating Adhesive Layering on a Yankee Cylinder” (Attorney Docket No. 2014; GP -06-1); U.S. Patent Application Serial No. 11/451112 (Publication No. US 2006-0289133), filed June 12, 2006, entitled “Fabric Crested Sheet for Dispensers” (Attorney Docket No. 2015; GP-06-12); US Patent Application Serial No. 11/451111, filed June 12, 2006, (Publication No. US 2006-0289134), entitled “Method for Manufacturing Fabric Creped Sheet for Dispensers” (Attorney Docket No. 20099; GP-05-10); U.S. Patent Application Serial No. 11/402609 (Publication No. US 2006-0237154), filed April 12, 2006, entitled “Absorbent Core Multilayer Paper Towel” (Attorney Docket No. 12601; GP-04-11); US Patent Application Serial No. 11/151761, filed June 14, 2005, (Publication No. US 2005/0279471) entitled "Method of Fabric Creping with Solid Lugs to Obtain an Absorbent Sheet with Intra-Fabric Drying" (Attorney Docket No. 12633; GP-03 -35); U.S. Patent Application Serial No. 11/108458, filed April 18, 2005 (Publication No. US 2005-0241787), entitled “Fabric Creping and Intra-Fabric Drying Method to Obtain Absorbent Sheet” (Attorney Docket No. 12611P1; GR-03-33- one); U.S. Patent Application Serial No. 11/108375, filed April 18, 2005 (Publication No. US 2005-0217814), entitled “Fabric Crepe / Draw Method for Absorbent Sheet” (Attorney Docket No. 12389P1; GP-02-12-1); US Patent Application Serial No. 11/104014, filed April 12, 2005 (Publication No. US 2005-0241786), entitled “Wet Press Fabrics and Towels with Increased CD Extraction and Low Elongation Ratios Made Using the Fabric Method of Cresting with Hard Lugs” (Attorney Docket No. 12636; GP-04-5); U.S. Patent Application Serial No. 10/679862 (Publication No. US 2004-0238135), filed October 6, 2003, entitled "Fabric Creping Method for Manufacturing Absorbent Sheet" (Attorney Docket 12389; GP-02-12); US Provisional Patent Application Serial No. 60/903789, filed February 27, 2007, entitled “Fabric Creping Method with Long Production Cycle” (Attorney Docket 20216; GP-06-16); and U.S. Patent Application Serial No. 60/808863, filed May 26, 2006, entitled "Fabric Crepe-Absorbent Sheet with Variable Local Base Weight" (Attorney Docket No. 20179; GP-06-11). The above-mentioned applications are particularly significant for the selection of equipment, materials, operating conditions, and so on with respect to the creped products of the present invention, and descriptions of these applications are incorporated herein by reference.

Although the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those skilled in the art. In view of the foregoing discussion, relevant prior art in the art and references, including co-pending applications discussed above in connection with the “Related Art” and “Detailed Description”, all contents of which are incorporated herein by reference, no further description is deemed necessary.

Claims (16)

1. Absorbent cellulosic sheet having a variable local base weight containing a paper-fibrous mesh, consisting of:
(a) a plurality of elongated densified regions of pressed paper fibers, the densified fibers generally oriented in the machine direction (MD) of the sheet and having a relatively low local base weight, as well as leading and trailing edges at their longitudinal ends; and
(b) a plurality of fiber-rich, bonnet regions connected to a plurality of elongated densified regions, the bonnet regions having (i) a relatively high local base weight and (ii) a plurality of ridges extending across the machine direction (CD) having vaulted CD profiles relative to the front and the trailing edges of the plurality of elongated densified areas. 2. The absorbent cellulosic sheet according to claim 1, wherein the elongated densified regions are further characterized by an MD / CD ratio of densified regions of 6 to 10. 3. The absorbent cellulosic sheet according to claim 1, wherein the fiber-enriched cap regions have a fiber orientation offset in the CD direction of the sheet. 4. Absorbent cellulosic sheet according to claim 1, in which the compacted area with a relatively low base weight, extending in the machine direction, have a shift in the orientation of the fiber along the CD direction of the sheet. 5. The absorbent cellulosic sheet according to claim 1, wherein the sheet has a porosity equal to or greater than 9 g / g and up to 12 g / g. 6. Absorbent cellulosic sheet according to claim 1, having a CD elongation of more than 6%. 7. The absorbent cellulosic sheet according to claim 1, wherein the densified areas are arranged in a repeating pattern of a plurality of generally parallel linear arrays that are staggered longitudinally staggered relative to each other, so that a plurality of intermediate linear arrays are located between a pair of CD-aligned compacted areas;
wherein, the densified regions are arranged and arranged such that the fiber-enriched region between the pair of CD-aligned densified regions is freely distributed in the CD by the leading and trailing edges of the densified regions of at least one intermediate linear array thereof. 8. The absorbent cellulosic sheet according to claim 7, in which the front and rear MD edges of the fiber-rich, bonnet areas are generally concave inward, so that the central MD area of the fiber-rich areas is smaller than the MD area at the side edges of the fiber-rich areas. 9. The absorbent cellulosic sheet of claim 8, wherein the fiber-enriched bonnet areas occupy from about 95% to about 50% of the area of the sheet. 10. Absorbent cellulosic sheet according to claim 9, in which typical areas within areas with relatively high base weights show a characteristic local base weight of at least 25% higher than the characteristic local base weights of typical areas in areas with low base weights. 11. Absorbent cellulosic sheet according to any one of claims 1 to 10, while this sheet has a specific volume of more than 5.5 ((mils / 8 layers) / (lbs / foot)) (more than 0.085 (mm / 8 layers / g / m ² ), (i) has a porosity of 9 g / g or more when it has a base weight of 23 lbs / foot (37.5 g / m ² ) or less, and (ii) has a porosity of 7 g / g or more when it has a base weight of more than 23 lbs / stop (37.5 g / m ² ). 12. A method of manufacturing a tape-creped absorbent cellulose sheet, comprising stages in which:
(a) the paper pulp is subjected to compressive dehydration to form an incipient web having an obviously random distribution of the orientation of the paper fiber;
(b) applying a dehydrated web having an obviously random distribution of fiber orientation onto a transfer surface moving at a first speed;
(c) tape creping the web from the transfer surface at a consistency of from about 30% to about 60% using a patterned creping tape, the creping step being carried out under pressure in a crepe press clip defined between the transfer surface and the creping tape, the tape being moves with a second speed less than the speed of the aforementioned transfer surface, and the tape pattern, pressure parameters, speed difference and web consistency are chosen so that the lotion is secured from the transfer surface and redistributed on the creping tape, forming a web with a grid having a plurality of connecting regions with different local base weights, including at least (i) a plurality of fiber-rich, bonnet regions with a high local base weight, connecting by (ii) a plurality of elongated densified regions of pressed paper fiber, the elongated densified regions having a relatively low local base weight and generally oriented along the machine nnogo direction (MD) of the sheet, wherein the elongated densified regions are further characterized MD / CD ratio of at least 1.5 and
(d) drying the web, the sheet having a specific volume greater than 5.5 ((mil / 8 layers) / (lb / foot)) (greater than 0.085 (mm / 8 layers / g / m ² ) and (i) has a porosity of 9 g / g or more when it has a base weight of 23 lbs / foot (37.5 g / m ² ) or less, or (ii) has a porosity of 7 g / g or more when it has a base weight of more than 23 lbs / stop (37.5 g / m ² ). 13. The method according to item 12, in which the hat area includes extendable macro folds. 14. The method of claim 12, further comprising the step of pulling macro folds by pulling the web along an MD sheet. 15. The method according to any one of paragraphs.12-15, which includes additional steps, where
d) applying the web to an American tumble dryer;
e) crepe fabric from an American tumble dryer; and
f) wind the web onto a spool;
tissue crepe / reel crepe functioning from about 1 to about 20. 16. The method according to clause 15, which shows the ratio of the increase in thickness /% winding crepe, comprising from about 1.5 to about 5.

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