RU2425918C2 - Absorbing cellulose web of regenerated cellulose microfibres and method of its production - Google Patents

Abstract

FIELD: textile, paper.

SUBSTANCE: absorbing cellulose web is designed for fabrics or towels and contains cellulose paper-forming fibres and fibrillated regenerated cellulose microfibres at their specified ratio. Fibrillated fibres represent cellulose regenerated from a solution. A dissolvent is an N-oxide of tertiary amine or an ionic liquid. Fibrillation of a microfibre is controlled so that the fibre has lower granularity and reduced beating rate compared to non-fibrillated regenerated cellulose microfibre. Microfibre has CSF-value of beating rate below 100 ml., weighted average diameter is less than 1 micron, weighted average length is below 400 micron, and fibre density is more than 2 billion fibres/gramme. There is also a method proposed to produce an absorbing cellulose web.

EFFECT: simultaneous improvement of softness and CD-extensibility in wet condition at lower module at the specified tensile strength, improved draping, increased absorbing ability.

41 cl, 11 tbl, 89 ex, 35 dwg

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on the following provisional US patent applications:

(a) provisional application for US patent serial number 60/784228 (according to the book of records of the lawyer No. 2014/2014 * 4), published March 21, 2006, entitled “ Absorbent Sheet Having Lyocell Microfiber Network ”;

(b) provisional application for US patent serial number 60/850467 (according to the book of records of the lawyer No. 2014/2014 ** **), published October 10, 2006, entitled “ Absorbent Sheet Having Lyocell Microfiber Network ”;

(c) provisional application for US patent No. 60/850681 (according to the book of records of the lawyer No. 12645), published October 10, 2006, entitled " Method of Producing Absorbent Sheet with Increased Wet / Dry CD Tensile Ratio "; and

(d) provisional application for US patent No. 60/881310 (according to the book of records of the lawyer No. 20218), published January 19, 2007, entitled " Method of Making Regenerated Cellulose Microfibers and Absorbent Products Incorporating Same ".

Priority Prior Art US Patent Application Nos. 60/784228; 60/850467; 60/850681 and 60/881310 are thus claimed and their discoveries are incorporated by citation in this application.

FIELD OF THE INVENTION

The present invention generally relates to an absorbent fabric and, in particular, to an absorbent fabric and towel made from paper-forming fibers, such as softwood and hardwood pulp containing regenerated cellulose microfiber.

BACKGROUND

Regenerated cellulose lyocell fiber is well known. Typically, lyocell fiber is made from reprecipitated cellulose formed from an aqueous solution of amine oxide. A common method consists of spinning lyocell fiber from a solution of cellulose in aqueous tertiary amine N-oxide; for example, from N-methylmorpholine N-oxide (NMMO). The solution is usually extruded through a suitable spinneret into an aqueous coagulating bath to obtain finished fibers. These fibers are widely used in textiles. Due to the fact that lyocell fiber includes highly crystalline alpha cellulose, it tends to fibrillate, which is undesirable in most textiles and is considered a disadvantage. In this regard, US Pat. No. 6,235,392 and U.S. Patent Application Publication No. 2001/0028955, Luo et al ., For the first time describe various methods for producing lyocell fiber with a reduced tendency to fibrillate.

On the other hand, fibrillation of cellulose fibers is desirable in some applications, such as filtration. For example, US patent No. 6042769 Gannon et al . first describes a method for preparing lyocell fibers that are easy to fibrillate. The fibers thus obtained can be treated with a disintegrator, as noted in column 5 of patent No. 6042769. See lines 30 onwards. See also US patent No. 5725821, Gannon et al . The highly fibrillated lyocell fibers have been found to be suitable for filter media with a very high degree of productivity. In this regard, see US Patent Application No. 2003/0168401 and US Application Publication No. 2003/0177909, Koslow.

As is known, lyocell fibers having fiber diameters and lengths similar to paper-forming fibers are used in the manufacture of an absorbent web. In this regard, US Pat. No. 6,841,038 to Horenziak et al ., For the first time describes a method and apparatus for preparing an absorbent web comprising lyocell fibers. See figure 2 of patent No. 6841038, which first describes the traditional method of drying in air (TAD process) for preparing an absorbent sheet. US patent No. 5935880, Wang et al ., Also for the first time describes non-woven fiber networks, including lyocell fibers. See also U.S. Patent Application Publication No. 2006/0019571. Such fibers tend to be flocculent and are thus extremely inconvenient for use in the traditional paper manufacturing wet spinning process for absorbent rolls. In addition, the traditional lyocell fiber is used in patent No. 6841038, for example, with increased mass fractions (40% of the surface layer of the wire, Example 1) in order to strongly influence the properties of the fabric.

While the use of lyocell fibers in absorbent materials is known, it has not been previously appreciated that very thin lyocell fibers or other regenerated cellulose fibers with extremely low grain sizes can provide unique combinations of properties such as wet strength, absorbency and softness , even when used in the composition of the paper-forming mass in limited quantities. According to the present invention, it has been found that regenerated cellulosic microfiber can be easily incorporated into a hardwood and softwood paper-forming fiber matrix to enhance network characteristics and provide higher quality characteristics even when using lower than higher quality paper-forming fibers.

In US patent No. 6461476, Goulet et al., It was first described that the extensibility in the wet / dry state of air-dried fabrics and towels can be increased by treating the pulp with a baking powder, an agent to increase wet strength and an agent to increase dry strength condition. Chemical leavening agents, also referred to as plasticizers, are often used in the manufacture of paper tissue and towels. One preferred disintegrant composition includes a plasticizer system comprising a substantially equimolar, ion-pair mixture of an anionic surfactant and a cationic quaternary ammonium compound. See U.S. Patent No. 6,245,197 to Oriaran et al. For details. Typically, disintegrants are added to the paper pulp composition at relatively low fiber concentrations, such as those in the source pool or machine pool. In this regard, see US Pat. No. 5,785,813 to Smith et al. ; as well as Figure 1 in it. Also see US Patent No. 5,501,768, Hermans et al., Example 9, Column 13, where sulfated hardwood fiber was treated with a baking powder in a column dispersant.

The following patents also for the first time describe papermaking processes in which a baking powder composition is added after the fiber is pulped: US Pat. No. 6,273,995, Ikeda et al .; US patent No. 6146494, Seger et al . and US patent No. 4441962, Osborn, III .

For pretreatment of finely divided fibers, a combination of oil and a surfactant was proposed before the manufacture of the absorbent web. In this regard, reference is made to US patent No. 6001218, Hsu et al., And US patent No. 6074527, also from Hsu et al . According to patents No. 6001218 and No. 6074527, the pulp suspension was treated at an elevated temperature with oil and a surfactant in order to obtain softer products.

It will be apparent to those skilled in the art that the prior art is filled with pulp treatments designed to provide a softer and / or more durable product. In this regard, the following references are referred to for general information: US Patent Publication No. 2003/0024669 (US Serial Number 09/852997) entitled “ Use of Hydrophobically Modified Polyaminamides With Polyethylene Glycol Esters in Paper Products ”, Kokko; US Patent Publication No. 2002/0162635 (US Serial Number 10/143674), entitled “ Softer and Higher Strength Paper Products and Methods of Making Such Products ”, Hsu; US Patent Publication No. 2002/0088575 (US Serial Number 09/942468) entitled “ Enzymatic Treatment of Pulp to Increase Strength ”, Lonsky et al .; US Patent Publication No. 2004/0123962 (US Serial Number 10/335133), entitled “ Amino-Functionalized Pulp Fibers ”, Shannon et al .; US patent No. 6582560, entitled “ Method for Using Water Insoluble Chemical Additives with Pulp and Products Made By Said Method ”, Runge et al. See also U.S. Patent Publication No. 2003/0159786 (US Serial Number 10/389073) entitled “ Method For Using Water Insoluble Chemical Additives with Pulp and Products Made by Said Method ”, Runge et al .; US Patent Publication No. 2004/0045687 (US Serial Number 10/242571) entitled “ Method for Using Water Insoluble Chemical Additives With Pulp and Products Made by Said Method ”, Shannon et al .; US patent No. 6344109, entitled " Softened Comminution Pulp ", Gross; and U.S. Patent Publication No. 2002/0074097 (US Serial Number 10/017361), entitled “ Softened Comminution Pulp, ” also from Gross.

It was found that according to the present invention, the preliminary treatment of the pulp with a baking powder further enhances the properties of the final paintings containing regenerated cellulose microfiber.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an absorbent tissue paper for towels or towels contains from about 99 wt.% To about 70 wt.% Paper-forming fiber made from cellulose pulp, and from about 1 wt.% To about 30 wt.% Fibrillated regenerated cellulose microfiber having a Canadian standard of grinding (CSF), the degree of grinding of less than 175 ml The paper-forming fiber is arranged into a fiber matrix and microfiber lyocells are dosed and distributed in the fiber matrix to form a microfiber network, as shown in Figure 1, which is a micrograph of creped fabric with 20% cellulose microfiber. The fibrillation of the regenerated cellulose microfiber is controlled in such a way that it has a reduced grain size and a reduced degree of grinding compared with the unfibrillated regenerated cellulose fiber from which it is made, so that the microfiber provides increased absorbency, strength or softness, usually providing one or more of the following characteristics :

(a) the absorbent web exhibits an increased value of water absorption capacity (SAT) and an increased wet tensile value compared to a similar web obtained without regenerated cellulose microfiber;

(b) the absorbent web has an increased wet / dry stretch ratio compared to a similar web obtained without regenerated cellulose microfiber;

(c) the absorbent web has a smaller geometric mean (GM) tear modulus than a similar web having similar tensile values obtained without regenerated cellulose microfiber; or

(d) the absorbent web has an increased volume compared to a similar web having similar tensile values obtained without regenerated cellulose microfiber. Particularly suitable fibers are obtained from a solution of cellulose with dissolved cellulose, including a solvent selected from ionic liquids and N-oxides of tertiary amines.

The present invention also provides products with unusually high wet / dry stretch ratios, making it possible to produce softer products, since the dry strength of a commodity towel, for example, is often determined by the wet strength required. A particularly preferred embodiment of the invention includes a web made with fiber that has been pre-treated with a high concentration baking powder.

Additional features and advantages of the invention will be apparent from the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to the following figures:

Figure 1 is a micrograph showing a creped tissue with 20% regenerated cellulose microfiber;

Figure 2 is a micrograph of unrefined regenerated cellulose fiber with a thickness of 1.5 denier, having a grain size of 16.7 mg / 100 m;

Figure 3 is a micrograph of regenerated cellulose fiber, milled to sieve number 14;

Figure 4 is a micrograph of regenerated cellulose fiber, milled to a sieve number of 200;

Figures 5-9 are micrographs at an increased magnification of a fibrillated regenerated cellulose microfiber, which was passed through a mesh with a sieve number 200 according to the Bayer-McNett classifier (Bauer-McNett);

Figures 10-15 are graphical representations of the physical properties of hand webs containing regenerated cellulosic microfiber, where Figure 10 is a graph of the dependence of the volume of hand cloth on elongation (breaking length), Figure 11 is a graph of roughness versus elongation, Figure 12 represents is a graph of the dependence of opacity on elongation, Figure 13 is a graph of the dependence of the module on elongation, Figure 14 is a graph of the relationship and the canvas for hands from extensibility and Figure 15 is a graph of the dependence of the volume of the canvas for hands from ZDT binding;

Figure 16 is a photomicrograph with a magnification of 250 softwood hand cloths without fibrillated regenerated cellulose fiber;

Figure 17 is a photomicrograph with a magnification of 250 softwood hand cloths comprising 20% fibrillated regenerated cellulose microfiber;

Figure 18 is a schematic diagram of a wet-pressing paper machine that can be practiced in accordance with the present invention;

Figure 19 is a graph of the dependence of softness (panel) on two-layer GM extensibility for the fabric base of the fabric with a density of 12 pounds / foot sheets (19.5 g / m ² ) of southern pulp and regenerated cellulose microfiber obtained by the CWP method ;

Figure 20 is a graph of panel softness versus extensibility for various fabric webs;

Figure 21 is a graph of volume versus elongation for a creped CWP web base.

Figure 22 is a plot of MD elongation versus CD elongation for a CWP tissue base of a web;

Figure 23 is a graph of the dependence of the GM-modulus of the gap from GM-extensibility for the fabric base of the canvas;

Figure 24 is a graph of the change in elongation versus% microfibre in the fabric and the base of the towel web;

Figure 25 is a graph of the dependence of paper density on elongation for the fabric base of the canvas;

Figure 26 is a graph of paper density versus elongation for the CWP base of the web;

Figure 27 is a graph of the dependence of the magnitude of the two-layer SAT on CD extensibility in the wet state;

Figure 28 is a plot of wet CD versus dry CD extensibility for a CWP base web;

Figure 29 is a micrograph obtained by scanning electron microscope (SEM) of a crepe tissue without microfiber;

Figure 30 is a micrograph of creped fabric with 20% microfiber;

Figure 31 is a graph of the relationship between the breaking length in the wet state and the breaking length in the dry state for various products, showing the effect of the regenerated cellulosic microfiber and baking powder on the tensile strength of the products in tension;

Figure 32 is a graph of the dependence of the GM modulus of the gap on the breaking length, showing the effect of the regenerated cellulose microfiber and baking powder on the strength of the product;

Figure 33 is a graph of volume versus breaking length, showing the effect of regenerated cellulose microfiber and baking powder on the volume of the final product;

Figure 34 is a flowchart illustrating fiber pretreatment before feeding paper pulp into a paper machine; and

Figure 35 is a graph of TAPPI opacity versus paper density showing that regenerated cellulosic microfiber significantly increases the opacity of the fabric base of the web obtained with the pulp returned to circulation.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in detail below with reference to several embodiments and numerous examples. This discussion is for illustration purposes only. Modifications and particular examples within the scope of the present invention as claimed in the appended claims will be readily apparent to those skilled in the art.

The terms used herein are provided in their usual meaning consistent with the typical definitions given below; mil stands for thousandths of an inch; mg is milligrams and m ² is square meters, percent is mass percent (dry matter), “ton” or “T” is short ton (2000 pounds), “m-ton” is metric ton (1000 kg) and so on . Unless otherwise explicitly indicated otherwise, the version of the testing method used is equivalent to that which was valid as of January 1, 2006 and the test samples were prepared in standard TAPPI conditions; that is, kept in an atmosphere of 23 ± 1.0 ° C (73.4 ± 1.8 ° F) at 50% relative humidity for at least about 2 hours.

Absorbency of the products of the invention was measured with a simple absorbency meter. A simple absorbency meter is an applicable apparatus, in particular for measuring hydrophilicity and absorbency characteristics of tissue samples, napkins or towels. In this test, a 2.0 inch (5.1 cm) diameter tissue, tissue, or towel sample was placed between the top flat plastic cover and the grooved bottom of the sample plate. A tissue, tissue, or towel sample disc is held in place by a 1/8-inch (0.32 cm) wide flange circumference. The sample was not compressed in the holder. Deionized water was added to the sample at 73 ° F (23 ° C) in the center of the bottom of the sample plate through a channel with a diameter of 1 mm. This water was at a height of hydrostatic pressure minus 5 mm. Spreading was initiated by pulsed introduction introduced at the beginning of the measurement by the device mechanism. Water was thus absorbed by a sample of cloth, napkin or towel from this central entry point, radially distributed under the action of capillary forces. When the absorption rate of water decreased below 0.005 g of water in 5 seconds, the test was completed. The amount of water withdrawn from the reservoir and absorbed by the sample was weighed and given as grams of water per square meter of sample or grams of water per gram of web. Practically applied Gravimetric Absorbency Testing System from M / K Systems Inc. This commercial system, which can be obtained from M / K Systems Inc., 12 Garden Street, Danvers, Mass., 01923. The water absorption capacity (WAC), also referred to as SAT, is actually determined by the device itself. WAC is defined as the point on the graph where the time-mass curve has a “zero” slope, that is, the sample stops absorption. The completion criterion for the test is defined as the maximum change in the mass of water absorbed over a fixed period of time. Essentially, the moment is estimated as a zero slope in the time-mass graph. The program uses a change of 0.005 g over a 5 second time interval as a criterion for completion; until a “slow SAT” is indicated, in which case the completion criterion is an increase of 1 mg in 20 seconds.

Unless explicitly stated otherwise, the terms “paper density”, BWT, bwt, and so on, refer to a stack weight of sheets of 3,000 square feet (279 m ² ) of product. Concentration refers to the percent solids in the resulting web structure, for example, calculated on a completely dry mass. “Air drying” means incorporating residual moisture, typically up to about 10% moisture for pulp and up to about 6% for paper. The structure of the canvas, which is in the stage of formation, containing 50% water and 50% completely dry pulp, has a concentration of 50%.

The terms “cellulosic”, “cellulosic web” and the like are intended to mean any product including a paper-forming fiber containing cellulose as a main component. “Paper-forming fibers” include raw wood pulps or recycled (secondary) cellulosic fibers or fiber mixtures containing cellulosic fibers. Fibers suitable for the manufacture of web structures according to this invention include: non-wood fibers such as cotton fibers or derivatives of cotton, manila hemp, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed filament, pineapple foliage fibers; and wood fibers, such as those obtained from deciduous and coniferous trees, including softwood fibers, such as softwood unbleached sulfated fibers of the northern varieties and southern varieties; solid wood fibers such as eucalyptus, maple, birch, poplar or the like. The paper-forming fibers used in connection with the invention are typically naturally occurring pulp-derived fibers (as opposed to fibers isolated from solution, such as lyocell or rayon) that are isolated from their source by any of a number of hydrofracturing methods close to the method, known in the art, including sulfate, sulfite, polysulfide, soda boiling, etc. The pulp can be bleached, if desired, by chemical means, including the use of chlorine, chlorine dioxide, oxygen, alkaline peroxide and so on. The naturally occurring pulp-derived fibers are here simply referred to as “pulp-derived” paper-forming fibers. The products of the present invention may include a mixture of conventional fibers (either derived from primary pulp or secondary sources) and high-grain lignin-rich tubular fibers, such as bleached chemical thermomechanical pulp (BCTMP). The fibers obtained through the pulp thus also include finely divided fibers such as BCTMP, as well as thermomechanical pulp (TMP), chemical thermomechanical pulp (CTMP) and alkaline peroxide mechanical pulp (APMP). “Paper pulps” and similar terms refer to aqueous compositions, including paper-forming fibers, optionally wet strength resins, disintegrants, and the like, for the manufacture of paper products. In order to calculate the relative percentages of paper-forming fibers, the content of fibrillated lyocell was excluded, as described below.

Unbleached sulphated mild wood fiber is a low-disperse fiber produced by the well-known sulphating (sulphate) pulping method from conifers and includes mild unbleached sulphated fiber of northern and southern varieties, unbleached sulphated fiber of Douglas fir and so on. Unbleached sulfated softwood fibers generally have a lignin content of less than 5 wt.%, A weighted average fiber length of more than 2 mm, as well as an arithmetic average fiber length of more than 0.6 mm.

Unbleached sulfated solid wood fiber is produced by a sulfate cooking method from solid wood sources, that is, eucalyptus, and also usually has a lignin content of less than 5 wt.%. Unbleached sulfated solid wood fibers are shorter than soft wood fibers, typically have a weight average fiber length of less than 1 mm and an arithmetic average length of less than 0.5 mm or less than 0.4 mm.

Recycled fiber can be added to the pulp in any quantity. While any suitable recycled fiber can be used, recycled fiber with relatively low levels of wood fiber is preferred in many cases, for example, recycled fiber with less than 15 wt.% Lignin or less than 10 wt. .% lignin content may be preferably depending on the composition of the mixture of paper pulp used and application.

The thickness of the calipers and / or the volume given here can be measured as the thickness of the calipers on 8 or 16 paintings, as indicated. The caliper thickness and the volume of the hand blade are based on a thickness of 5 webs. The canvases were placed one above the other and the caliper thickness was measured near the central part of the stack. Preferably, test samples were aged in the atmosphere at 23 ± 1.0 ° C (73.4 ± 1.8 ° F) at 50% relative humidity for at least about 2 hours and then measured on a Thwing-Albert 89-II- model JR or Progage Electronic thickness gauge with anvils of 2-inch (50.8 mm) diameter, constant load of 539 ± 10 grams and a descent speed of 0.231 inches / sec (0.59 cm / sec). To test the final product, each product web tested must have the same number of layers as the commercial product. For preliminary testing, eight canvases are selected and stacked together. When testing napkins, napkins were unfolded before stacking. To test the base of the web without devices for winding the tape into a roll, each test fabric should have the same number of layers as it turns out without a device for winding the tape into a roll. Separate layers should be used to test the base of the web without the bobbin of the paper machine. The canvases were stacked, jointly aligned in a line in the longitudinal direction. On custom embossed or printed products, you must try to avoid measurements in these areas, if possible. Volume can also be expressed in units of volume / mass (specific volume) by dividing the caliper thickness by paper density .

The term “dewatering by densifying the web or paper pulp structure” refers to mechanical dehydration by wet pressing on a dewatering cloth, for example, in some embodiments, by applying mechanical pressure constantly to the surface of the web structure, as in the gap between the pressure roller and the pressing shoe, where the structure of the canvas is in contact with paper cloth. The term “sealing dehydration” is used to distinguish between methods in which the initial dewatering of the web structure was carried out mainly by thermal methods, as in the case of, for example, US Pat. No. 4,529,480, Trokhan, and US Pat. No. 5,607,551 to Farrington et al. Dehydration by densifying the web structure, therefore, refers, for example, to removing water from the web structure that is undergoing formation, having a concentration of less than 30% or about, by applying pressure to it and / or increasing the concentration in the web structure by about 15 % or more by applying pressure to it.

Creping can be expressed as a percentage, calculated by the formula:

Percentage of creping = [speed of the first reel / speed of the American dryer] × 100%

The web structure, creped at a surface speed of 100 fpm (feet per minute) (30.5 m / min) from the drying cylinder to the bobbin at a speed of 80 fpm (24.4 m / min), has crepe creping of 20%.

The creping adhesive used to secure the fabric to the drying cylinder of the American dryer is preferably hygroscopic, rewet, substantially cross-linked. Examples of preferred adhesives are those that contain the poly (vinyl alcohol) of the general type described in US patent No. 4528316, Soerens et al . Other acceptable adhesives are first described in the co-sent patent application with serial number US 10/409042 (publication of US patent No. 2005-0006040 A1), published April 9, 2003, entitled " Improved Creping Adhesive Modifier and Process for Producing Paper Products " (book records of lawyer No. 2394). The opening of the patent No. 4528316 and application 10/409042 are included in this description as a reference material. Suitable adhesives are optionally provided with modifiers and so on. It is preferable to use a cross-linking agent and / or modifier in the calculated amounts or not for the entire amount of glue.

“Baking powder”, “baking powder composition”, “plasticizer” and similar terms refer to compositions used to reduce extensibility or soften absorbent paper products. Typically, these compositions include surfactants as an active ingredient and are further discussed below.

The “degree of grinding” (CSF) was determined according to TAPPI T227 OM-94 (Canadian Standard Method).

The term “web made without regenerated cellulose microfiber” and the like refers to a web made in essentially the same way having essentially the same composition as the web made with regenerated cellulosic microfibre, except that the paper pulp does not include regenerated cellulose microfiber, which replaces a paper-forming fiber having essentially the same composition as another paper-forming fiber in the web. Thus, with respect to a web having 60 wt.% Soft wood fiber of the northern grades, 20 wt.% Solid wood fiber of the northern grades and 20 wt.% Regenerated cellulose microfiber, which is produced by the CWP method, a similar web without regenerated cellulose microfiber is produced by the same CWP-method with 75 wt.% Soft wood fiber of northern varieties and 25 wt.% Solid wood fiber of northern varieties.

Lyocell fibers are solvent-formed cellulosic fibers obtained by extruding a cellulose solution into a coagulating bath. Lyocell fiber is thinner than cellulose fiber produced by other known methods, which are based on the formation of soluble chemical derivatives of cellulose and their subsequent decomposition to regenerate cellulose, for example, in a viscose process. Lyocell is a general term for fibers formed directly from a solution of cellulose in an amine-containing medium, usually in a tertiary amine N-oxide. The production of lyocell fiber is the subject of numerous patents. Examples of solvent spinning processes for producing lyocell fibers are described in US Pat. No. 6,235,392 to Luo et al .; US patent No. 6042769 and 5725821, Gannon et al ., which are included in this description as a reference material.

“MD” stands for longitudinal direction and “CD” stands for transverse direction.

Opacity was measured using the TAPPI test method, T425-OM-91 or equivalent.

The term “predominant” and similar terminology means a content of greater than 50 wt.%. The fibrillated lyocell content in the web was calculated based on the total fiber mass in the web; where the relative amount of other paper-forming fibers was calculated excluding the content of fibrillated lyocell. So, if the web, which consists of 20% fibrillated lyocell, 35 wt.% Mild wood fiber and 45 wt.% Solid wood fiber, contains solid wood as the predominant paper-forming fiber because 45/80 paper-forming fiber (excluding fibrillated lyocell) is solid wood fiber.

Dry tensile strengths (MD- and CD-), elongations, their ratios (modules), tensile modulus, load and tensile were measured using an Instron standard testing device or other suitable elongation tensile tester, which can be configured in various ways typically on strips of 3 or 1 inch (7.6 or 2.5 cm) wide of fabric or towels, aged in the atmosphere at 23 ± 1 ° C (73.4 ± 1 ° F) at 50% relative humidity for 2 hours . The tensile test is carried out at a slider speed of 2 inches / min (5.1 cm / min). The tensile strength is sometimes simply referred to as “tensile” and is given in breaking length (km), g / 3 inches or g / inch.

Product modulus (also referred to as tensile modulus or tensile modulus) was determined by the method for measuring the tensile strength described above, using a sample with a width of 1 inch (2.5 cm), and the measured modulus is a break in the slope of the load curve / elongation, measured in the load range of 0-50 grams. The “tensile modulus” is the tensile stress divided by the elongation at break.

The geometrically averaged (GM) fracture modulus is expressed in grams / 3 inches /% voltage, unless otherwise specified. The percentage of tension is dimensionless, and there is no need to define units. Elongation values refer to discontinuous values, unless otherwise indicated explicitly. Tensile strengths were given in g / 3 inches or g / cm at break.

The GM break modulus is calculated using the following formula:

[(MD elongation / MD elongation at break) × (CD elongation / CD elongation at break)] ^1/2

Relations of extensibility are simply relations of quantities determined by the above methods. Unless explicitly stated otherwise, the property of extensibility is a property of a dry web.

TEA is a measure of strength and is given by CD-TEA, MD-TEA or GM-TEA. Total Absorbed Energy (TEA) is calculated as the area under the load-elongation curve using a tensile meter, as previously described above. The area is based on the amount of elongation achieved when the web extends to break and the load applied to the web drops to 65% of the peak tensile load. Since the thickness of the paper web is usually unknown and varies during the test, it is common practice to ignore the transverse width of the web and report “load” on the web as a load per unit length or usually in units of grams per 3 inches of width (7.6 cm). To calculate TEA, the load was converted to grams per millimeter and the area was calculated by integration. Elongation units are millimeters per millimeter, so the final TEA units become g-mm / mm ² .

The wet stretch of the fabric of the present invention was measured using a three-inch wide ribbon of fabric, which was folded into a loop, clamped in a special fixture called the Finch Cup, then immersed in water. The Finch Cup, which is available from Thwing-Albert Instrument Company, Philadelphia, Pa., Was mounted on a tensile meter equipped with a 2.0 lb (0.91 kg) cage with a Finch Cup flange fixed between the lower cam of the meter and the ends of the fabric loop clamped in the upper cam of the tensile tester. The sample was immersed in water, which was brought to a pH of 7.0 ± 0.1 and the extensibility was tested 5 seconds after immersion. The values were divided by two, as required for the calculation for the loop.

The ratio of wet / dry extensibility was expressed as a percentage by multiplying the ratio by 100. For towel-type products, the ratio of wet / dry CD extensibility is most significant. For the purposes of this specification and claims, the term “wet / dry ratio” or similar terms refers to the ratio of CD-wet / dry stretch ratios unless otherwise indicated explicitly. In the case of hand canvases, the MD and CD values are approximately equivalent.

A plasticizer or additional baking powder was calculated as the mass “in the state immediately after delivery” of a commercial composition with a baking powder per ton of completely dry fiber, using a commercially available composition with a baking powder, without taking into account additional diluents or dispersants that can be added to the composition after receipt from the seller.

Baking powder compositions typically include cationic or anionic amphiphilic compounds or mixtures thereof (hereinafter referred to as surfactants) combined with other diluents and non-ionic amphiphilic compounds, where the usual surfactant content in the baking powder composition varies from about 10 wt.% To about 90 wt.%. Diluents include propylene glycol, ethanol, propanol, water, polyethylene glycols and non-ionic amphiphilic compounds. Diluents are often added to the surfactant composition in order to make the latter more easily processed (i.e., with reduced viscosity and melting point). Some diluents are artifacts of the synthesis of a surfactant in a package (e.g. propylene glycol). Non-ionic amphiphilic compounds, in addition to controlling the properties of the composition, can be added to enhance the wettability of the disintegrant, where both disintegration and preservation of the absorbency are necessary for the substrate to which the disintegrant is applied. Non-ionic amphiphilic compounds can be added to baking powder compositions to disperse water-immiscible surfactant packets in water streams, such as those found in papermaking. Alternative non-ionic amphiphilic compounds or mixtures of various non-ionic amphiphilic compounds, as shown in US patent No. 6969443, Kokko , can be carefully selected to predictably control the loosening properties of the final baking powder composition.

When formulating a composition with a disintegrant directly from surfactants, the additional disintegrant includes amphiphilic additives, such as a nonionic surfactant, i.e. polyethylene glycol fatty esters and diluents, such as propylene glycol, respectively, up to about 90 wt. % of the applied composition with baking powder; however, with the exception that the diluent content is more than about 30 wt. %; non-amphiphilic diluent is excluded in order to calculate the composition with added baking powder per ton of fiber. Similarly, the water content is excluded when calculating the additional baking powder.

The term “Type C” quat refers to an imidazolium-based surfactant, while the term “Type C” disintegrant refers to a disintegrant composition that includes type C quat. A preferred type C disintegrant composition includes Type C quat and an anionic surfactant, as first described in US Pat. No. 6,245,197, mixed with nonionic amphiphilic components and other diluents, as first described in US Pat. No. 6,969,443, the opening patents No. 6,245,197 and No. 6969443 are included in yes This description is for reference only.

It has been found that according to the present invention, increased ratios of wet / dry CD stretch ratios are detected when paper-forming fibers are pretreated with a loosening composition or plasticizer before being incorporated into the web structure. In this regard, the present invention can use disintegrants, including amidoamine salts derived from amines partially acid neutralized. Such substances are first described in US patent No. 4720383, Evans, Chemistry and Industry , July 5, 1969, pp. 893-903; Egan, J. Am. Oil Chemist's Soc Vol. 55 (1978), pages 118-121 and Trivedi et al., J. Am. Oil Chemist's Soc , June 1981, pp. 754-756, which are incorporated herein by reference; as shown, plasticizers are often available commercially as complex mixtures more often than as individual compounds. While the following discussion will focus on the predominant particles of a surfactant, it should be understood that commercially available mixtures and compositions should generally be used in practice.

Quasoft 202-JR is an acceptable substance that includes a surfactant obtained by alkylating a product by condensation of oleic acid and diethylene triamine. Synthesis conditions with a lack of an alkylating agent (e.g. diethyl sulfate) and only one alkylation step, followed by pH adjustment to protonate unleaded particles, result in a mixture consisting of cationic ethylated and cationic unleaded particles. A smaller fraction (for example, about 10%) of the obtained amidoamine is cyclized to imidazoline compounds. Since only the imidazoline moieties of these substances are quaternary ammonium compounds, the compositions as a whole are pH sensitive. Therefore, in the practical implementation of the present invention with this class of chemicals, the pH in the headbox should be about 6-8, more preferably 6-7, and most preferably 6.5-7.

Quaternary ammonium compounds, such as dialkyl dimethyl quaternary ammonium salts, are also acceptable, especially when the alkyl groups contain from about 10 to 24 carbon atoms. These compounds have the advantage of being relatively insensitive to pH.

Biodegradable plasticizers may be used. Representative biodegradable cationic plasticizers / disintegrants are first described in US Pat. Nos. 5,312,522; 5,415,737; 5262007; 5264082 and 5223096, which are included in this description as a reference material. The compounds are biodegradable diesters of quaternary ammonium compounds, quaternized amino esters and esters based on biodegradable vegetable oil, functionalized with quaternary ammonium chloride and dierucil dimethylammonium diester chloride, and are representative blended representative.

Baking powder compositions may include dialkyl dimethyl ammonium salts of the formula:

bis-dialkylamidoammonium salts of the formula:

As well as dialkylmethylimidazolium salts (quads of type C) of the formula:

where each R may be the same or different and each R represents a hydrocarbon chain having a chain length of from about 12 to about 22 carbon atoms, and may be saturated or unsaturated; and wherein said compounds are associated with a suitable anion. One acceptable salt is a dialkylimidazolium compound and the associated anion is methyl sulfate. Typical quaternary ammonium surfactants include hexamethonium bromide, tetraethylammonium bromide, lauryltrimethylammonium chloride, dihydrogenated fatty aliphatic dimethylammonium methyl sulfate, oleylimidazolium and so on.

A component of a nonionic surfactant, such as PEG diols and PEG mono or fatty acid diesters, and PEG mono or fatty alcohol diesters, either individually or in combination with a quaternary ammonium surfactant, can also be used. . Suitable compounds include the reaction product of a fatty acid or fatty alcohol with ethylene oxide, for example a polyethylene glycol fatty acid diester (PEG diols or PEG diesters). Examples of non-ionic surfactants that can be used are polyethylene glycol dioleate, polyethylene glycol dilaurate, polypropylene glycol dioleate, polypropylene glycol dilaurate, polyethylene glycol monooleate, polyethylene glycol monolaurate and further polypropylene glycol monolate and monol. Additional details can be found in US patent No. 6969443, Bruce Kokko (according to the book of records of the lawyer 2130; FJ-99-12), entitled " Method of Making Absorbent Sheet from Recycle Furnish ".

After treatment with a baking powder, the pulp is mixed with strength adjusting agents, such as a wet strength improver (WSR), optional dry strength enhancing agents, and so on, until a web is formed. Suitable stable wet strength agents are known to those skilled in the art. A complete but not exclusive list of useful strength improvers includes urea-formaldehyde resins, melamine-formaldehyde resins, glyoxylated polyacrylamide resins, polyamidamine-epihalohydrin resins and the like. Shrink polyacrylamides are prepared by reacting acrylamide with diallyldimethylammonium chloride (DADMAC) to form a cationic polyacrylamide copolymer, which is ultimately reacted with glyoxal to form a cationic crosslinked resin that increases the wet strength of glyoxylated polyacrylamide. These materials are generally described in US Pat. Nos. 3,556,932 to Coscia et al . And 3,556,933 to Williams et al ., Which are incorporated herein by reference. Resins of this type are commercially available under the brand name PAREZ. Various acrylamide / -DADMAC / glyoxal molar ratios can be used to prepare cross-linked resins that are useful as wet strength reagents. In addition, other dialdehydes can replace glyoxal to obtain wet shrink strength characteristics. Particularly suitable are the wet-resistant polyamidamine-epichlorohydrin resins which are, for example, sold under the trademarks Kymene 557LX and Kymene 557H by Hercules Inc., Wilmington, Delaware and Amres® from Georgia-Pacific Resins, Inc. These resins and a method for preparing 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. A detailed description of polymeric epihalohydrin resins is given in chapter 2: “ Alkaline-Curing Polymeric Amine-Epichlorohydrin,” Espy in “ Wet Strength Resins and Their Application” (L. Chan, Editor, 1994), which is incorporated herein by reference. An acceptable list of wet strength resins is described by Westfelt in Cellulose Chemistry and Technology Volume 13, p. 813, 1979, which is incorporated herein by reference.

Suitable dry strength agents include starch, guar gum, polyacrylamides, carboxymethyl cellulose (CMC) and the like. Carboxymethyl cellulose is particularly applicable, an example of which is sold under the trademark Hercules CMC , Hercules Inc., Wilmington, Delaware.

According to the invention, the regenerated cellulosic fiber is obtained from a cellulose solution including cellulose dissolved in a solvent including tertiary amine N-oxides or ionic liquids. The solvent composition for dissolving cellulose and preparing unmodified cellulose solutions typically includes tertiary amine oxides such as N-methylmorpholine-N-oxide (NMMO) and similar compounds listed in US Pat. No. 4,242,221 to McCorsley , which is incorporated herein by reference reference material. Cellulose solutions may contain poor solvents for cellulose such as water, alkanols or other solvents, as will be apparent from the discussion that follows.

Suitable cellulose solvents are listed in table 1 below.

Table 1
Examples of tertiary amine N-oxide solvents Tertiary amine N-oxide % water % pulp N-methylmorpholine-N-oxide up to 22 up to 38 N, N-dimethyl-ethanol-amine-N-oxide up to 12.5 up to 31 N, N-dimethylcyclohexylamine-N-oxide up to 21 up to 44 N-methyl homopiperidine-N-oxide 5.5-20 1-22 N, N, N-triethylamine-N-oxide 7-29 5-15 2- (2-hydroxypropoxy) -N-ethyl-N, N, -dimethylamide-N-oxide 5-10 2-7.5 N-methylpiperidine-N-oxide up to 17.5 5-17.5 N, N-dimethylbenzylamine-N-oxide 5.5-17 1-20

See also US patent No. 3508945, Johnson , which is included in this description as a reference material.

Details regarding the preparation of cellulose solutions, including cellulose dissolved in suitable ionic liquids, and the regeneration of cellulose from them, are shown in US patent application No. 10/256521; US Patent Publication No. 2003/0157351, Swatloski et al. entitled “ Dissolution and Processing of Cellulose Using Ionic Liquids, ” which is incorporated herein by reference. Here again acceptable levels of solvents that do not dissolve the cellulose can be included. This patent application generally describes a method for dissolving cellulose in an ionic liquid without derivatization and regeneration of cellulose in various structural forms. It has been described that the solubility of cellulose and the properties of the solution can be controlled by the selection of components for an ionic liquid with small cations and halide or pseudo-halide anions that favor dissolution. Preferred ionic liquids for dissolving cellulose include liquids with cyclic cations, such as the following: imidazolium; pyridinium; pyridazinium; pyrimidinium; pyrazinia; pyrazolium; oxazolium; 1,2,3-triazolium; 1,2,4-triazolium; thiazolium; piperidinium; pyrrolidinium; quinolinium and isoquinolinium.

Processing techniques for ionic liquids / cellulose solutions are also discussed in US Pat. No. 6,808,557 to Holbrey et al ., Entitled “ Cellulose Matrix Encapsulation and Method ”, which is incorporated herein by reference. See also U.S. Patent Application No. 11/087496; US Patent Publication No. 2005/0288484, Holbrey et al., entitled “ Polymer Dissolution and Blend Formation in Ionic Liquids, ” as well as US Patent Application No. 10/394989; US Patent Publication No. 2004/0038031, Holbrey et al., entitled “ Cellulose Matrix Encapsulation and Method ”, which are incorporated herein by reference. For ionic liquids, the following documents generally provide additional details: US Patent Application No. 11/406620, US Patent Publication No. 2006/0241287, Hecht et al., Entitled “ Extracting Biopolymers From a Biomass Using Ionic Liquids ”; US Patent Application No. 11/472724, US Patent Publication No. 2006/0240727, Price et al., entitled “ Ionic Liquid Based Products and Method of Using the Same ”; US Patent Application No. 11/472729; US Patent Publication No. 2006/0240728, Price et al., entitled “ Ionic Liquid Based Products and Method of Using the Same ”; US Patent Application No. 11/263391, US Patent Publication No. 2006/0090271, Price et al., entitled “ Processes For Modifying Textiles Using Ionic Liquids ”; and U.S. Patent Application No. 11/375963 to Amano et al. (publication No. 2006/0207722), which are included in this description as a reference material. Some ionic liquids and pseudo-ionic liquids that can be used are first described by Konig et al., Chem. Commun. 2005, 1170-1172 , which is incorporated herein by reference.

The term “ionic liquid” refers to a molten composition comprising an ionic compound, which preferably is a stable liquid at temperatures less than 100 ° C. under normal pressure. Typically, such liquids have a very low vapor pressure at 100 ° C, less than 75 mbar or about, and preferably less than 50 mbar or less than 25 mbar at 100 ° C. The most suitable liquids will have a vapor pressure of less than 10 mbar at 100 ° C and often the vapor pressure is so low that it is negligible and not easily measurable, as it is less than 1 mbar at 100 ° C.

Suitable commercially available ionic liquids are Basionic ^™ ionic liquids available from BASF (Florham Park, NJ) and are listed in Table 2 below.

table 2
Typical ionic liquids
Standard Name abbreviation Basionic ™ Class The product's name ChemAbstr Number EMIM Cl ST 80 1-ethyl-3-methylimidazolium chloride 65039-09-0 EMIM CH ₃ SO ₃ ST 35 1-ethyl-3-methylimidazolium methanesulfonate 145022-45-3 BMIM Cl ST 70 1-butyl-3-methylimidazolium chloride 79917-90-1 BMIM CH ₃ SO ₃ ST 78 1-butyl-3-methylimidazolium methanesulfonate 342789-81-5 MTBS ST 62 methyl tri-N-butylammonium methyl sulfate 13106-24-6 MMMPZ MeOSO ₃ ST 33 1,2,4-trimethylpyrazolium methyl sulfate EMMIM EtOSO ₃ ST 67 1-ethyl-2,3-dimethylimidazolium ethyl sulfate 516474-08-01 MMMIM MeOSO ₃ ST 99 1,2,3-trimethyl-imidazolium methyl sulfate 65086-12-6 Acidic Name abbreviation Basionic ™ Class The product's name ChemAbstr Number HMIM Cl AC 75 methylimidazolium chloride 35487-17-3 HMIM HSO ₄ AC 39 methylimidazolium hydrosulfate 681281-87-8

EMIM HSO ₄ AC 25 1-ethyl-3-methylimidazolium hydrosulfate 412009-61-1 EMIM AlCl ₄ AC 09 1-ethyl-3-methylimidazolium tetrachloroaluminate 80432-05-9 BMIM HSO ₄ AC 28 1-butyl-3-methylimidazolium hydrosulfate 262297-13-2 BMIM AlCl ₄ AC 01 1-butyl-3-methylimidazolium tetrachloroaluminate 80432-09-3 The main Name abbreviation Basionic ™ Class The product's name ChemAbstr Number Emim acetate BC 01 1-ethyl-3-methylimidazolium acetate 143314-17-4 BMIM acetate BC 02 1-butyl-3-methylimidazolium acetate 284049-75-8 Liquid at room temperature Name abbreviation Basionic ™ Class The product's name ChemAbstr Number EMIM EtOSO ₃ LQ 01 1-ethyl-3-methylimidazolium ethyl sulfate 342573-75-5 BMIM MeOSO ₃ LQ 02 1-butyl-3-methylimidazolium methyl sulfate 401788-98-5 Low viscosity Name abbreviation Basionic ™ Class The product's name ChemAbstr Number EMIM SCN VS 01 1-Ethyl-3-methylimidazolium thiocyanate 331717-63-6 BMIM SCN VS 02 1-Butyl-3-methylimidazolium thiocyanate 344790-87-0 Functionalized Name abbreviation Basionic ™ Class The product's name ChemAbstr Number acetate COL FS 85 Choline Acetate 14586-35-7 salicylate col FS 65 Choline Salicylate 2016-36-6 MTEOA MeOSO ₃ FS 01 Tris (2-hydroxyethyl) methylammonium methyl sulfate 29463-06-7

Cellulose solutions including ionic liquids having here a solute content of about 5% by weight of unmodified cellulose are commercially available from Aldrich. These compositions use alkyl methyl imidazolium acetate as a solvent. It has been found that choline-based ionic liquids are not particularly suitable for dissolving cellulose.

After receiving the cellulose solution, it is spun into fiber, fibrillated and incorporated into the absorbent web, as described below.

In general, the invention relates, in part, to the improvement of paper pulp properties by the action of cellulose microfibers in order to improve softness, volume and absorbency, while maintaining or improving strength. Synthetic cellulose, such as lyocell, is broken down into micro- and nanofibres and added to traditional wood pulp at a relatively low level of about 10%. Favorable properties of fibrillated lyocell include: biodegradability, the presence of hydrogen bonds, dispersion, the ability to re-boil and smaller microfibers than, for example, fibers that can be obtained by molding from a solvent.

Fibrillated lyocell or its equivalent have advantages over splittable melt-formed fibers. Synthetic fibers with a thickness of the order of microdeny are formed in various forms. For example, nylon / PET fiber with a thickness of 3 denier in a so-called wedge-shaped configuration can be split into 16 or 32 segments, usually in a method of hydrobinding. Each 16-segment fiber segment should have a grain size of about 2 mg / 100 m compared to eucalyptus pulp having about 7 mg / 100 m. It is unfortunate that a number of drawbacks are associated with this approach in traditional wet application methods. Dispersion is less than optimal. Melt formed fibers must be split before a web is formed, and there is no effective way to do this. The most affordable polymers for these fibers are not biodegradable. The granularity is smaller than that of wood pulp, but still high enough so that they must be used in significant quantities and make up an expensive part of the paper pulp. Ultimately, the lack of hydrogen bonds requires other methods of retaining fibers in the fabric.

Fibrillated lyocell has fibers that can be small, of the order of 0.1-0.25 microns (μm) in diameter, calculated on a grain size of 0.0013-0.0079 mg / 100 m. Provided that these fibers are available as individual fibers - separated from the original fiber - the density of the pulp fibers can be impressively increased with a very low level of addition. Even fibers not separated from the original fiber may provide an advantage to the pulp. Product properties, such as dispersion, reboilability, hydrogen bonds and biodegradability, are preserved since the fibers are cellulose.

Lyocell fiber has important differences from wood pulp fibers. The most important difference is the length of lyocell fibers. For wood pulp fibers, only a micron length is possible, and therefore, action in the area of direct fiber-to-fiber communication. Wood pulp fibrillation by pulverizing the pulp leads to stronger, denser canvases. Lyocell fibers, however, are potentially as long as the original fibers. These fibers can act as independent fibers and increase volume while maintaining or improving strength. Swamp pine and Southern mixed wood (MSHW) are two examples of fibers that are of lower quality relative to pulp of the highest level of softness. The term “pulp of the highest level of quality”, as used here, refers to pulps from softwoods of northern grades and eucalyptus, usually used in light industry to obtain products of the mildest class for a bath, for face and towels. Swamp pine is coarser than the unbleached sulfated softwood of the northern grades, and mixed hardwood of the southern grades are both coarser and more finely chopped than the commercially available eucalyptus. A lower grain size and lower content of fine particles in the market pulp of the highest quality level leads to a higher fiber density, expressed as the number of fibers per gram (N or N _{i> 0.2} ) in table 1. Grit and length values in table 1 were obtained using the OpTest fiber quality analyzer. The results were obtained by the formulas below:

Northern bleached sulfated softwood (NBSK) and eucalyptus have more fiber per gram than bog pine and hardwood. Smaller graininess leads to higher fiber density and smoother webs.

Table 3
Fiber properties Sample Type of C
mg / 100 m Fine inclusion,% L _n mm N mm / g L _{n, i> 0.2} mm N _{i> 0.2} , mm / g southern hardwood Pulp 10.1 21 0.28 35 0.91 eleven solid wood of the southern grades and a small number of fine inclusions Pulp 10.1 7 0.54 eighteen 0.94 eleven eucalyptus aracruz Pulp 6.9 5 0.50 29th 0.72 twenty southern softwood Pulp 18.7 9 0.60 9 1,57 3 soft wood of northern grades Pulp 14.2 3 1.24 6 1.74 four a mixture of southern varieties (30% softwood / 70% hardwood) Canvas base 11.0 eighteen 0.31 29th 0.93 10 30% Southern softwood / 70% Eucalyptus Canvas base 8.3 7 0.47 26 0.77 16

For comparison, “unmodified” or “original” lyocell fibers have a grain size of 16.6 mg / 100 m before fibrillation and a diameter of about 11-12 microns. The fibers have a grain size of the order of 0.001-0.008 mg / 100 m. Thus, the fiber density can be impressively increased at relatively low levels of addition. The fiber length of the original fiber can be selected, and the fiber length of the fibrils can depend on the initial length and size when cut during the fibrillation process.

In its various aspects, the present invention relates, in part, to an absorbent paper web for fabric or towel, comprising from about 99 wt. % to about 70 wt. % pulp obtained through the pulp of a paper-forming fiber and from about 1 wt. % to about 30 wt. % fibrillated regenerated cellulose microfiber having a CSF value of less than 175 ml, where the paper-forming fiber is organized into a fiber matrix and lyocell microfiber is dosed and distributed in the fiber matrix to form a microfiber network therein. Microfiber fibrillation is controlled in such a way that it has a reduced grain size and a reduced degree of grinding compared to the regenerated cellulose microfiber from which it is made, so that the microfiber network provides at least one of the following properties to the absorbent web:

(a) the absorbent web has an increased SAT and an increased wet elongation compared to a similar web obtained without regenerated cellulose microfiber;

(b) the absorbent web has a higher ratio of wet / dry CD extensibility compared to a similar web obtained without regenerated cellulose microfiber;

(c) the absorbent web has a smaller GM tear modulus than a similar web having similar tensile values obtained without regenerated cellulose microfiber; or

(d) the absorbent web has an increased volume compared to a similar web having similar tensile values obtained without regenerated cellulose microfiber. Typically, an absorbent web has a wet / dry stretch ratio of at least 25% higher than the ratio of a similar web obtained without regenerated cellulose microfiber; typically an absorbent web has a wet / dry stretch ratio of at least 50% higher than the ratio of a similar web obtained without regenerated cellulose microfiber. In some cases, the absorbent web has a wet / dry stretch ratio of at least 100% higher than the ratio of a similar web obtained without regenerated cellulose microfiber.

In some embodiments, the absorbent web of the invention has a GM tear modulus of at least 20% less than a similar web having similar tensile values obtained without regenerated cellulose microfiber, and the absorbent web has a specific volume of at least 5% higher than a similar web having similar tensile values obtained without regenerated cellulose microfiber. The specific volume is easily achieved at least 10% higher than that of a similar web having similar tensile values obtained without regenerated cellulose microfiber.

One of a series of preferred embodiments contains from about 5 wt. % to about 15 wt. % regenerated cellulose microfiber, where the regenerated cellulose microfiber has a CSF value of less than 150 ml. More typically, the regenerated cellulosic microfiber has a CSF value of less than 100 ml; but a CSF value of less than 50 ml or 25 ml is preferred in many cases. Similarly, regenerated cellulose microfiber having a CSF value of 0 ml is used. While any suitable microfiber size can be used, the regenerated cellulosic microfiber typically has an average diameter of less than about 2.0 microns, for example, from about 0.1 to about 2 microns. Regenerated cellulose microfiber may have a grain size of less than about 0.5 mg / 100 m; from about 0.001 mg / 100 m to about 0.2 mg / 100 m in many cases. The product typically has a paper weight of from about 5 pounds per foot of sheets of 3,000 square feet (8.1 g / m ² ) to about 40 pounds per foot of sheets of 3,000 square feet (65.1 g / m ² ). For a towel, the base of the web may have a paper weight of from about 15 pounds per foot of sheets of 3000 square feet (24.4 g / m ² ) to about 35 pounds per foot of sheets of 3000 square feet (57.0 g / m ² ) and the resulting through the pulp, the paper-forming fiber includes predominantly softwood fiber, usually predominantly unbleached sulfated softwood fiber of southern varieties and at least 20 wt. % obtained through pulp paper-forming fiber from solid wood fiber.

In another aspect of the invention, there is provided an absorbent paper web for a fabric or towel, comprising from about 99% to about 70 wt. % obtained through the pulp of a paper-forming fiber and from about 1 wt. % to about 30 wt. % regenerated cellulose microfiber having a CSF value of less than 100 ml, where the absorbent web has an absorbency of at least about 4 g / g. Absorbency of at least about 4.5 g / g; at least about 5 g / g or at least about 7.5 g / g is sometimes preferred. In numerous cases, the absorbent web has an absorbency of from about 6 g / g to about 9.5 g / g.

Another product of the invention is an absorbent paper web for tissue or towel, comprising from about 99% to about 70 or 65 wt. % obtained through the pulp of a paper-forming fiber and from about 1 to about 30 wt. % or 35 wt. % regenerated cellulose microfiber having a CSF value of less than 100 ml, where the regenerated cellulose microfiber has a fiber density of greater than 50 million fibers / gram. Regenerated cellulose microfiber may have a weighted average diameter of less than 2 microns, a weighted average length of less than 500 microns and a fiber density of more than 400 million fibers / gram, or regenerated cellulosic microfiber may have a weighted average diameter of less than 1 micron, a weighted average length of less than 400 microns and a fiber density of more than less than 2 billion fibers / gram. In one embodiment, the regenerated cellulose microfiber has a weighted average diameter of less than 0.5 microns, a weighted average length of less than 300 microns and a fiber density of more than 10 billion fibers / gram, and in another embodiment, the regenerated cellulose microfiber has a weighted average diameter of less than 0.25 microns, a weighted average length of less than 200 microns and a fiber density of more than 50 billion fibers / gram. A fiber density greater than 200 billion fibers / gram is available if necessary.

In a further aspect of the invention, there is provided an absorbent fabric web comprising at least about 75 wt. % obtained through pulp paper-forming fiber, where solid wood fiber is predominant, obtained through pulp paper-forming fiber, and from about 1 wt. % to about 25 wt. % regenerated cellulose microfiber having a CSF value of less than 100 ml. This product may have a basis weight of less than about 15 pounds per ream of sheets in 3000 square feet (24.4 g / m ^2), such as from about 7 pounds per ream of sheets in 3000 square feet (11.4 g / m ²⁾ up to approximately 13 pounds per foot of sheets of 3,000 square feet (21.2 g / m ² ). The canvas may include at least about 75 wt. % obtained through pulp paper-forming fiber from a mixture of hard wood and soft wood. A preferred solid wood fiber is the unbleached sulfated solid wood fiber of the southern grades. In one embodiment, the pulp-forming paper-forming fiber includes at least about 20 wt. % obtained through pulp of a paper-forming fiber from softwood fiber (excluding the content of lyocell fiber). Preferably, the fabric web has an increased GM tensile strength compared to a similar fabric obtained without regenerated cellulose microfiber, for example, where the fabric web has a GM tensile strength of at least about 20, 30, or 40% higher than a similar web with a similar paper weight obtained without regenerated cellulose microfiber. Thus, the fabric web also has increased MD and CD elongations compared to a similar fabric produced without regenerated cellulose microfiber. In one embodiment, the fabric web has a CD elongation of at least 5%.

Another aspect of the invention relates to the base of a fabric web including pulp-derived paper-forming fiber, which is predominantly solid wood fiber, and from about 5 wt. % to about 35 wt. % regenerated cellulose microfiber, where the base of the web has at least about 20% greater GM elongation than a similar web with similar paper density and similar softness, obtained without regenerated cellulose fiber. This web typically has a paper density of from about 4 to about 12 pounds per foot of sheets per 3000 square feet (6.5 to 19.5 g / m ² ), such as a paper weight of about 5 to about 8 pounds per foot of sheets of 3000 square feet (8.1 to 13.0 g / m ² ) or about 5 to about 7 pounds per foot of sheets of 3000 square feet (8.1 to 11.4 g / m ² ).

A fabric web base is also provided, including pulp-forming paper-forming fiber, which is predominantly solid wood fiber, the base of the web has a GM stretch of more than 300 g / 3 in. (39.4 g / cm) and a paper density of about 4 pounds per foot of sheets of 3,000 square feet (6.5 g / m ² ) to about 10 pounds per foot of sheets of 3,000 square feet (16.3 g / m ² ), where the base of the web includes from about 1 to about 30 or about 35 wt. % fibrillated regenerated cellulose microfiber having a density of more than 400 million fibers per gram.

A further aspect of the invention provides an absorbent cellulosic web comprising:

(a) cellulosic pulp-forming paper-forming fibers in an amount of from about 70 wt.% to about 98 wt.% and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 2 wt.%, where said regenerated cellulose fibers have an average fiber width of less than about 4 microns. The average fiber width may be less than about 2 microns; less than about 1 micron or less than about 0.5 microns. The average fiber length of regenerated cellulose fibers may be less than about 500 micrometers; less than approximately 250 micrometers; less than approximately 150 micrometers; less than about 100 micrometers or an average lyocell fiber length of less than about 75 micrometers, if necessary.

Another product of the invention is an absorbent cellulosic web, including:

(a) cellulosic pulp-forming paper-forming fibers in an amount of from about 70 wt.% to about 98 wt.% and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 2 wt.%, where said regenerated cellulose fibers have an average fiber length of less than about 500 microns.

Another product is an absorbent cellulosic fabric, including:

(a) cellulose pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, the content of southern softwood pulp in pulp-derived paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt. % obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 1 wt.%, where said regenerated cellulose fibers have an average fiber length of less than about 500 μm, said absorbent cellulosic fabric has a TAPPI opacity greater than 55 units opacity. The web may have a TAPPI opacity greater than 60 opacity units or a TAPPI opacity greater than 63 opacity units. In some embodiments, the web has a paper density of less than 8 pounds / foot of sheets per 3000 square feet (13.0 g / m ² ) and normalized TAPPI opacity greater than 6 TAPPI opacity per pound of paper density (3.7 opacity according to TAPPI g / m ² basis weight). In other cases, such a web has a normalized paper density greater than 6.5 units of opacity according to TAPPI per pound of paper density (4.0 units of opacity according to TAPPI per g / m ² paper density). The gain in opacity is particularly useful in connection with the fiber returned to circulation, for example, where the web is basically a fiber returned to circulation. Fabric bases of a web that have a paper weight of from about 9 pounds to about 11 pounds / foot of sheets (14.6 g / m ² to 17.9 g / m ² ) made from recycled fiber typically have a normalized opacity greater than 5 units of opacity according to TAPPI per pound of paper density (3.1 units of opacity according to TAPPI per g / m ² paper density). The products listed below do not necessarily have the above opacity characteristics.

Another product is an absorbent cellulosic fabric, including:

(a) cellulosic pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, where the content of southern softwood in pulp-obtained pulp-forming paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt. .% obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 1 wt.%, where said regenerated cellulose fibers have an average fiber width of less than about 4 microns.

The following product, which can be produced according to the invention, is an absorbent cellulosic fabric, including:

(a) cellulose pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, the content of southern softwood pulp in pulp-derived paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt. % obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 1 wt.%, where said lyocell fibers have a fiber density of more than about 350,000,000 fibers / g. Regenerated cellulose may have a fiber density greater than 50 million fibers / g; fiber density greater than 100 million fibers / g; fiber density greater than 500 million fibers / g; or a fiber density greater than 10 billion fibers / g.

Another product of the invention is an absorbent cellulosic web, including:

(a) cellulosic pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, the content of southern softwood in pulp-obtained pulp-forming paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt.% obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulose fibers in an amount of from about 30 wt.% to about 1 wt.%, said regenerated cellulose fibers have a fiber density of greater than about 350,000,000 fibers / g. This and other products may have a breaking length of at least 0.91 km; breaking length of at least 0.92 km; breaking length of at least 0.95 km or breaking length of at least 0.97 km.

The following product according to the invention is an absorbent cellulosic fabric, including:

(a) cellulosic pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, where the content of southern softwood in pulp-obtained pulp-forming paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt. .% obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulosic fibers in an amount of from about 30 wt.% to about 1 wt.%, where said regenerated cellulosic fibers have an average fiber length of less than about 500 μm, where said absorbent cellulosic fabric has a breaking length of at least 0 , 9 km.

Another product of the invention is an absorbent cellulosic web, including:

(a) cellulose pulp-derived paper-forming fibers in an amount of from about 70 wt.% to about 99 wt.%, the content of southern softwood pulp in pulp-derived paper-forming fibers in an absorbent cellulosic fabric is at least about 60 wt. % obtained through the pulp of a paper-forming fiber, excluding the content of regenerated cellulose; and

(b) fibrillated regenerated cellulosic fibers in an amount of from about 30 wt.% to about 1 wt.%, where said regenerated cellulosic fibers have an average fiber width of less than about 4 μm, said absorbent cellulosic fabric has a breaking length of at least 0, 9 km.

It has been found that the products of the invention exhibit unusually high wet / dry CD ratios when paper-forming fibers obtained through pulp are pretreated with a disintegrant composition. Wet / dry ratios of more than 30%, i.e., about 35% or large, are easily achieved; usually in the range of about 35 to 60%. Ratios of at least about 40% or at least about 45% can be seen in the examples below. The pulp is preferably processed at a high concentration, that is, greater than 2%, preferably greater than 3 or 4% and usually between 3-8% in the inlet stream of the machine pool, in a pulper, for example. The paper-forming fibers obtained through the pulp or at least a part of the paper-forming fibers obtained through the pulp can, for example, be pre-treated with a baking powder during pulping. All or some of the fibers may be pretreated; 50 wt.%, 75 wt.% And up to 100 wt.% Obtained through the pulp of the fiber can be pre-treated, including or excluding the content of regenerated cellulose, where pre-treatment may not be critical. Then the fiber can be ground, as you know, in a disk mill. Thus, a resin that improves dry strength and / or a resin that increases wet strength can also be used. Processing of the pulp obtained through the pulp can be carried out from about 1 to about 50 pounds of a disintegrant composition per ton of pulp obtained through the pulp (dry base) (0.5 to 25 kg per m-ton). From about 5-30 or 10-20 pounds of baking powder per ton of fiber obtained through the pulp (2.5-15 or 5-10 kg per m-ton) is suitable in most cases.

Pretreatment can be carried out for any acceptable length of time, for example at least 20 minutes, at least 45 minutes, or at least 2 hours. In general, pre-processing will be in the time range from 20 minutes to 48 hours. The pre-treatment time is calculated as the amount of time during which the aqueous paper-forming fiber obtained through the pulp is in contact with the aqueous baking powder before the formation of the fabric structure, which is in the formation stage. In acceptable amounts, a wet strength resin and a dry strength resin were added; for example, either one or both can be added to the web in amounts from 2.5 to 40 pounds per ton of paper-forming fiber obtained through the pulp (1.3 to 20 kg per m-ton).

The present invention also includes methods of obtaining, such as a method of obtaining an absorbent cellulosic fabric, including:

(a) obtaining an aqueous paper pulp with a fiber mixture containing from about 99% to about 70% obtained through pulp of a paper-forming fiber, where the fiber mixture also includes from about 1 wt. % up to 30 wt. % regenerated cellulose microfibers having a CSF value of less than 175 ml; (b) placing the aqueous paper pulp on a perforated base to form a structure of the web in the process of formation and at least partially dehydrating the resulting web structure; and

(c) drying the web structure to obtain an absorbent web. Typically, aqueous paper pulp has a concentration of 2% or less; even more typically, aqueous pulp has a concentration of 1% or less. The resulting structure of the canvas can be dehydrated by compaction with paper-forming cloth and transferred to the American drying apparatus and creped on it. Alternatively, a web-dehydrated web structure is applied to a rotating cylinder and a fabric that is creped on it, or a web structure that is in the process of formation, is at least partially dehydrated by air drying, or a web structure that is in the process of formation, is at least partially dehydrated by forced air drying. In many cases, the fiber blend includes unbleached sulfated softwood of the southern grades and unbleached sulfated softwood of the southern grades.

Another method of obtaining the base of the fabric web according to the invention includes:

(a) preparing an aqueous paper pulp comprising southern varieties of solid wood and fibrillated regenerated cellulosic microfiber having a CSF value of less than 100 ml and a fiber density of more than 400 million fibers per gram;

(b) placing the aqueous paper pulp on a perforated base to form an emerging web structure and at least partially dehydrating the resulting web structure; and

(c) drying the web structure to obtain an absorbent web. A fibrillated regenerated cellulose fiber may have a fiber density of more than 1 billion fibers per gram, or a fibrillated regenerated cellulose fiber may have a fiber density greater than 100 billion fibers per gram, if desired.

The invention is further illustrated in the following Examples.

EXAMPLES

Example 1

The study of the canvas for hands was carried out with soft wood of southern grades and fibrillated fiber lyocell. The original lyocell fiber had a thickness of 1.5 denier (16.6 mg / 100 m) with a length of 4 mm, see Figure 2, which was then fibrillated to achieve a degree of grinding <50 CSF. As can be seen from figures 3 and 4, the fibrillated fiber has a much lower grain size than the original fiber. Figures 5-9 show microphotographs of fibrillated lyocell material that was passed through a mesh with a 200 mesh sieve according to the Bauer McNett classifier. This material is commonly referred to as “finely divided inclusions”. In wood pulp, finely divided inclusions are mainly particles, not fibers. The fibrous nature of this material should allow it to interweave among many fibers and, therefore, increase the strength of the network. This material makes up a significant amount (16-29%) of fibrillated lyocell with a CSF value of 40.

The sizes of the fibers passing through the mesh with a sieve number of 200 are about 0.2 microns in size with a length of 100 microns. Using these dimensions, fiber density can be calculated as 200 billion fibers per gram. For comparison, a swamp pine may have three million fibers per gram and eucalyptus may have twenty million fibers per gram (Table 1). Comparing the finely divided fraction with the images of sieve number 14, it is obvious that these fibers are fibers that are split from the original unmilled fibers. Various forms of lyocell fiber designed for rapid fibrillation can lead to fibers with a diameter of 0.2 microns, which may have a length of 1000 microns or more instead of 100 microns.

One aspect of the invention is to improve the performance of southern pulp, but other applications are obvious: to further increase the softness of the highest quality fabric with a given strength, increase the softness of the secondary fiber, improve the hand feel of the towel, increase the strength of the towel when wet and increase the size Sat.

Figures 10-15 show the strong influence of fibrillated lyocell on the properties of the canvas for hands. Volume, opacity, smoothness, modulus and tear are improved at a given level of elongation. The results were compared as a function of extensibility, since strength is always an important variable in tissue products. In addition, unbleached sulfated wood pulp tends to fall on similar curves for a given variable, so it is advisable to shift to a new curve for a strong change in the properties of the final product. Fibrillated lyocell favorably alters the volume / strength curve (Figure 10). Some of the microfibers can be incorporated into the pores between much larger softwood fibers, but the overall result is that lyocell dissipates between the softwood fibers with an increase in network volume.

Fibrillated lyocell contributes to smoothness, which is measured as Bendtsen roughness (Figure 11). Bendtsen roughness is obtained by measuring the air flow between a weighted plate and a paper sample. Smoother webs allow less air flow. Small fibers can fill some surface pores, which should in other circumstances take place on a sheet of 100% soft wood. The strong effect of smoothness on an uncreped hand cloth should be maintained even after the creping process.

Opacity is another variable improved by lyocell (Figure 12). A large number of microfibers creates a huge surface area for light scattering. Below 80 opacity units is equivalent to canvases with an eucalyptus content of up to 100%, thus achieving this opacity in the case of 80% southern softwood is significant.

The hand canvas module is lower at a given extensibility with lyocell (Figure 13). As a result, drapability should improve. A large number of fibers gets into the network better and allows a more even distribution of the load. One of the drawbacks of southern softwood is its tendency to achieve less elongation in creped fabric than northern softwood. Obviously, lyocell can help overcome this shortcoming. The fibrillated lyocell improves the tear properties of the canvas for hands (Figure 14). Southern softwood often attracts attention due to its tensile strength relative to other unbleached sulfated pulps, so it is noticeable that fibrillated lyocell increases the tearing characteristics of softwood hand paintings. Rupture is usually considered an important property for tissue, but it shows a different way in which lyocell can enhance network properties.

The role of soft wood fibers can generally be described as ensuring the strength of the network, while solid wood fibers provide smoothness and opacity. Fibrillated lyocell has a length sufficient to improve network properties, while its low grain size provides the benefits of hardwood.

From the above, it is obvious that lyocell fibers are more different than wood pulp fibers. Wood pulp fiber is a complex structure comprising several layers (P, S1, S2, S3), each with single strands of cellulose arranged in a spiral around the fiber axis. During mechanical grinding of the mass, parts of the layers P and S1 are separated in the form of a finely divided product and fibers. These fibers are generally very short, possibly no longer than 20 microns. Fibers tend to act in close proximity to fibers when crossing with other fibers. Thus, wood pulp fibers tend to increase bond strength, web strength, web density and web elongation. The multilayer structure of the fiber wall with spiral fibers makes it impossible to split the wood fiber along its axis using commercial methods. In contrast, lyocell fiber has a much simpler structure, which allows the fibers to split along its axis. The resulting fibers are small, about 0.1-0.25 microns in diameter and as long as the original fiber. The length of the fibers is likely to be shorter than the “original” fiber, and the decay of multiple fibers may be insufficient. However, if a sufficient number of fibers can work as individual fibers, the properties of the paper can have a significant effect with a relatively low level of addition.

The relative grain sizes of pulp and paper pulp and lyocell can be discussed. Northern softwood (NBSK) has a grain size of about 14 mg / 100 m compared to marsh pine, 20 mg / 100 m. Southern mixed hardwood (MSHW) has a grain size of 10 mg / 100 m compared to 6.5 eucalyptus mg / 100 m. Lyocell fibers with diameters in the range of 0.1-0.25 microns should have grain sizes in the range of 0.0013-0.0079 mg / 100 m. One way to characterize the difference between the highest quality paper pulp and paper pulp southern varieties is the fiber density, expressed as the number of fibers per gram of paper masses (N). N is inversely proportional to grain size, thus, pulp of the highest quality level has a higher fiber density than pulp of southern varieties. Southern grades of pulp fiber density can be increased to equal or superior pulp fiber density of the highest quality level by adding fibrillated lyocell.

Lyocell microfibres have many attractive features, including biodegradability, dispersion, reboilability, low graininess and extremely low grain to length ratio (C / L). A low C / L ratio means that the strength of the web can be obtained with a lower level of binding, which makes the web more flexible (smaller modulus, as shown in figure 13).

Table 4 summarizes effects that are significant at a 99% confidence level (excluding where noted). The purpose of the various treatments was to measure the relative effects on strength. Southern softwood is less effective in increasing the strength of the net than northern softwood, so one topic of interest is whether lyocell can strengthen southern softwood. Pulp with 20% lyocell and 80% southern softwood is significantly better than 100% southern softwood. Volume, opacity and tear are higher at a given extensibility, while the roughness and modulus are smaller. These trends are directionally favorable for fabric properties.

Hand cloths for table 4 were obtained according to the TAPPI method T-205. Volumetric thickness in cubic centimeters per gram is obtained by dividing the caliper thickness by the density of the paper. Bendtsen roughness is obtained by measuring the air flow between a solid plate and a paper sample. “L” refers to the labeled side of the hand sheet that adheres to the metal plate during drying, while “U” refers to the non-labeled side. ZDT refers to lateral extensibility of the canvas for hands.

Table 4
The main effects of the properties of the hand cloth Test average value The effect of grinding the mass of soft wood Lyocell fibrillation effect Mutual effect of pulverization of lyocell mass Caliper thickness 5 cloths (cm ³ / g) 1.76 -0.19 0.15 Bendtsen roughness, side L- 1kg (ml / min) 466 -235 -101 28 (95%) Bendtsen roughness, side U- 1 kg (ml / min) 1482 137 (95%) ZDT fiber binding (psi, bar) 49, 3.4 36, 2.5 -11, -0.8 -13, -0.9 HS-gap, g 120 20 (95%) TAPPI Opacity 77 -four 13 Breaking length, km 3,5 1.8 -0.6 (95%) Hand canvas extension,% 2,4 0.9 -0.4 (95%) Elongation energy of the canvas for hands, kg-mm 6.7 5.3 -1.9 (95%) The tensile modulus of the canvas for hands, kg / mm ² 98 28 -eighteen

Table 4 repeats the advantages of fibrillated lyocell shown graphically in Figures 10-15: higher volume, better smoothness, higher tear, better opacity and lower modulus.

Table 5 compares the morphology of lyocell and softwood fibers, as measured by the OpTest Optical Fiber Quality Analyzer (FQA). The “original” lyocell fibers (Figure 2) have a grain size of 16.7 mg / 100 m similar to that of southern softwood varieties (20 mg / 100 m). After fibrillation, the grain size measured by FQA fell to 11.9, similarly to the soft wood of the northern varieties. Probably the resolution of the FQA is not able to accurately measure either the length and width, or the grain size of very thin fibers. The smallest fine particle measured by FQA is 41 microns. The narrowest width measured by FQA is 7 microns. Thus, a grain size of 11.9 mg / 100 m is not representative of fibrillated lyocell. Based on the calculations, a fiber with a diameter of one micron has a grain size of 0.17 mg / 100 m, and 0.1 micron fiber has a grain size of 0.0017 mg / 100 m. The average grain size of the lyocell is obviously less than 11.9 mg / 100 m. according to FQA measurements. The differences in fiber size are more apparent when comparing Figures 16 and 17. Figure 16 is a photomicrograph made with only unbleached sulfated softwood of southern varieties, milled by 1000 calls in a PFI mill, while Figure 17 is a hand canvas, produced with 80% of the same southern softwood and 20% ground lyocell fiber. The exceptionally low graininess of fibrillated lyocell relative to traditional wood pulp is evident.

Table 5
The morphology of fibrillated lyocell compared to whole lyocell and softwood FQA OpTest parameter Fibrillated lyocell Lyocell, 1.5 denier Southern softwood Ln mm 0.38 2.87 0.68 Lw mm 1,64 3.09 2.40 Lz mm 2,58 3.18 3.26 Fine inclusions (n),% 67.4 2.9 64.0 Fine inclusions (w),% 16.3 0.1 8.5 Curl Index (wt.) 0.36 0,03 0.19 Width, microns 16.5 20.1 29.9 Granularity, mg / 100 m 11.9 16.7 20.5 CSF-degree of grinding, ml 22 746

Combined softwood and southern hardwood are cheaper than pulp of the highest level of quality, but the softwood pulp's ability to produce soft tissue is less than desirable for some applications. Mills producing products of the highest quality level may require the purchase of fibers of the highest level of quality, such as northern softwood and eucalyptus for the highest quality of softness, which increases the price and adversely affects the balance of the milled fiber. According to the present invention, milled lyocell fibers were added to improve the quality of the pulp.

At high levels of pulverization, the fiber masses can be separated from the original fiber and work as independent micro- or possibly even nanofibres. The degree of fibrillation was measured according to the Canadian standard of degree of grinding (CSF). Unmilled lyocell has a milling degree of about 800 ml, and test quantities are prepared at about 400, 200 and 40 ml. It was hypothetically hypothesized that a high level of pulverization would produce the greatest effect at the lowest rate of addition. Larger grinding creates a higher content of very low-grain fibers, but can also reduce the average fiber length. It is preferable to maximize the production of fine-grained fibers while minimizing fiber cutting. In the described study, 4 mm hand webs were milled to 22 ml with an average fiber length (Lw) of 1.6 mm. As previously discussed, a value of 1.6 mm, according to FQA measurements, is not considered a true average value, but is only intended to show the direction of decreasing length when grinding the mass. The fibrillated lyocell obtained for the latter examples starts from 6 mm fibers with a grain size of 16.7 mg / 100 m before pulverization. Ideal fibers are significantly smaller than eucalyptus, while maintaining a sufficient length. In fact, pulverization significantly reduces the length of the fiber, however, they have a length sufficient to strengthen the fiber network.

Lyocell microfiber makes it possible to significantly increase the number of fibers / gram of paper pulp by adding only moderate amounts of microfiber. We can discuss the calculation results in table 6, from which we can see that fibrillated lyocell easily reaches a fiber density of more than a billion fibers per gram.

Table 6
Dimensions of fibrillated lyocell fiber D, microns C mg / 100 m Length mm N, million / g 0.1 0.0013 0.1 795775 0.25 0.0079 0.2 63662 0.5 0,031 0.3 10610 one 0,126 0.4 1989 2 0.50 0.5 398 11.5 16.6 6 one

In comparison, eucalyptus fiber, which has a relatively large number of fibers, has only up to about 20 million fibers per gram.

Example 2

This example of a hand canvas demonstrates that the advantage of fibrillated lyocell arises primarily from short, low-grain fibers, more so than from partially ground original fibers that inadvertently survived the pulverization process after the process. Lyocell with a size of 6 mm on 1.5 denier was ground to a grinding degree of 40 and separated into fractions in the Bauer McNett classifier using a mesh with mesh numbers 14, 28, 48, 100 and 200. The fiber length is the primary factor, which determines the passage of fibers through each mesh. Fractions with mesh numbers 14 and 28 were combined to create one fraction, subsequently referred to as “long fibers”. The fractions with sieve numbers 48, 100, 200 and the part passing through the sieve number 200 were pooled to form a second fraction, subsequently referred to as “short fibers”. Southern softwood was obtained by grinding its mass by 1000 revolutions in a PFI mill. Hand sheets were made at a paper density of 15 pounds / foot of sheets (24.4 g / m ² ), pressed at 15 psi (1.0 bar) for five minutes, and dried on a steam-heated drum. Table 7 compares hand sheets made with various combinations of softwood and fibrillated lyocell. Softwood alone (Sample 1) has low opacity, low elongation and low elongation. 20% of long fibers (Sample 2) moderately improve opacity and elongation, but not extensibility. 20% of short fibers (Sample 3) significantly increase the opacity, elongation and extensibility more significantly than non-ground lyocell (Sample 4). Sample 5 uses re-combined long fibers and short fibers to approximate the initial fibrillated lyocell. From this example, it may be obvious that the contribution of short fibers to the present invention is predominant.

Figure 18 illustrates one way of carrying out the present invention, in which a machine pool 50 , which can be divided into sections, is used to prepare paper pulps that are treated with chemicals that have different purposes depending on the nature of the various fibers used. In this embodiment, a split headbox is shown, thereby allowing the layered product to be obtained. The product of the present invention can be obtained from one or more pressure boxes, 20 , 20 'and, regardless of the number of pressure boxes, they can be layered or non-layered. The treated paper pulp is transported through various channels 40 and 41, through which it enters the headbox of the sickle forming machine 10 , which is well known, although any suitable configuration may be applied.

Figure 18 shows the part forming the structure of the web, or the wet part, with a liquid permeable element of the perforated base 11 , which may be of any acceptable configuration. The perforated base element 11 can be made of any of several known materials, including photopolymer fabric, cloth, woven or synthetic fiber mesh, with a very thin synthetic fiber insulating mat attached to the mesh. The element of the perforated base 11 is supported in a standard way on the rollers, including the remote roller 15 and the pressing roller 16 .

The resulting fabric 12 is supported on rollers 18 and 19, which are mounted relative to the outer roll 15 to guide the forming wire 12 until converging on the element of the perforated base 11 on the cylindrical remote roller 15 at an acute angle with respect to the element of the perforated base 11. The element of the perforated base 11 and the wire 12 move at the same speed and in the same direction, which is the direction of rotation of the outrigger roller 15. The forming wire 12 and the element of the perforated base 11 converge the surface of the forming roll 15 to form a wedge-shaped space or gap in which one or more jets of water or foamed liquid dispersion fibers can be injected and trapped between the forming wire 12 and the element of the perforated base 11 to enhance the flow through the wire 12 into the tray 22, where it collected for reuse in the process (returned to circulation through line 24).

The structure of the fabric W, which is in the process of formation, formed in the process, is carried out along the longitudinal direction 30 by the action of the element of the perforated base 11 to the pressing roller 16, where the wet structure of the fabric W, which is in the stage of formation, is transferred to the American dryer 26. The liquid is removed by pressing from the wet of the web structure W by the pressing roller 16, while the web structure is moved to the American drying apparatus 26, where it is dried and fixed by means of a creping knife 27. End Single web structure is collected on the tension roller 28.

Pit 44 is provided for collecting water squeezed out of paper pulp by a pressing roller 16, as well as collected water removed from the fabric by a Ule 29 cloth-washing machine. Water collected in pit 44 can be collected in a production line 45 for separate processing in order to remove surface active substance and fibers from the water and returning the recycled water back to the paper machine 10.

With CWP-applying apparatus of the type shown in Figure 18, the series of absorbent webs of paper pulp, with mixed hardwood / softwood pulp and comprising floured lyocell fiber. The general approach was to crush softwood to the required level and produce a mild / solid wood mixture in the mixing tank. After making a control sample from 100% pulp of paper pulp, additional samples were obtained by measuring microfiber in a mixture. Elongation is optionally corrected either by the action of baking powder or starch. The applied pulps of the southern grades are softwood and hardwood. Paper pulp of the “highest level of quality” was obtained from northern varieties of soft wood and eucalyptus. Tissue creping was kept constant to reduce the number of variables. 1.8 lb / T (0.9 kg / m-ton) 1145 PAE (0.8 kg / T) was used and 15 degree knives were used, except for towel samples for which 8-degree knives were used. The temperature of the dryer was constant, 248 ° F (120 ° C). Paper density, MDDT, CDDT and caliper thickness were measured on all rollers. CDWT and two-layer SAT were measured for some test samples and softness was examined using a panel of prepared testers using two-layer samples, 4 inches × 28 inches (10.2 cm × 71.1 cm), obtained from the base of the web on the outer side surface of the American dryer. Details and results are shown in tables 8-9 and Figures 19-30.

Table 8
Materials for testing the CWP method Wood pulp Microfibre The degree of grinding of soft wood [ml] 40% Southern softwood / 60% Southern hardwood 0 570 32% Southern softwood / 48% Southern hardwood 20 (217 CSF) 570 20% Southern softwood / 30% Southern hardwood 50 (217 CSF) 570 0 100 (217 CSF) 40% Southern softwood / 60% Southern hardwood 0 570 32% Southern softwood / 48% Southern hardwood 20 (40 CSF) 570 36% Southern softwood / 54% Southern hardwood 10 (40 CSF) 570 38% Southern softwood / 57% Southern hardwood 5 (40 CSF) 570 40% Northern softwood / 60% Southern hardwood 0 580 38% Northern softwood / 57% Southern hardwood 5 (40 CSF) 580 32% Northern softwood / 48% Southern hardwood 20 (40 CSF) 580 70% Southern softwood / 30% Southern hardwood 0 580 56% Southern softwood / 24% Southern hardwood 20 (40 CSF) 580 40% Southern softwood / 60% Southern hardwood 0 680 36% Southern softwood / 54% Southern hardwood 10 (40 CSF) 680 38% Southern softwood / 57% Southern hardwood 5 (40 CSF) 680 39% Southern softwood / 59% Southern hardwood 2 (40 CSF) 680 40% northern softwood / 60% eucalyptus 0 580 32% northern softwood / 48% eucalyptus 20 (40 CSF) 580 50% northern softwood / 50% eucalyptus 0 580 40% northern softwood / 40% eucalyptus 20 (40 CSF) 580

(Differences in the degree of grinding of soft wood arising from the grinding of the mass.)

Table 9
Physical properties of the base of the canvas (continued) Sample Finch Cured Wet CD, g / 3 in. (G / cm) GM-modulus of the gap g / m ² /% CD-TEA g-mm / mm ² MD-TEA g / mm ² CD-rupture module g / m ² /% MD modulus of the gap g / m ² /% one 39.6 0.13 0.70 83,4 18.8 2 38,4 0.13 0.79 73,4 20.3 3 40.3 0.10 0.83 79.2 20.5 four 47.1 0.12 0.88 98.1 22.6 5 41.5 0.12 0.83 77.6 22.3 6 41.2 0.13 0.66 76.9 22.1 7 47.8 0.09 0.80 101.8 22.5 8 43.5 0.14 0.81 94.8 20,0 9 41.1 0.12 0.83 78.9 21,4 10 41.8 0.14 0.84 84.6 20.7 eleven 63,2 0.18 1,08 103.9 38.5 12 55.1 0.27 1.34 99.3 30.5 13 47.7 0.24 1.26 74.1 30.7

fourteen 34.9 0.45 1.16 49.2 25,2 fifteen 39.2 0.10 0.77 74.0 20.7 16 37.3 0.10 0.73 70.3 19.8 17 7.4
(1,0) 38,2 0.11 0.71 75,5 19.3 eighteen 40.9 0.19 1.18 64.9 25.8 19 42.7 0.21 1.15 74.6 24.6 twenty 42.9 0.18 1,11 73.1 25.1 21 11.0
(1.4) 45.5 0.21 1.23 75.3 27.5 22 40.7 0.18 0.97 63.0 26.3 23 40.5 0.18 1,07 64.9 25.3 24 41.0 0.17 1,03 62,4 26.9 25 33.8 0.13 1,02 47.7 24.0 26 39.1 0.12 1,02 66.9 22.8 27 46.9 0.18 1.36 66.3 33,4 28 39.7 0.16 1.17 56.9 27.7 29th 42.8 0.14 1,02 70.1 26,4 thirty 42.6 0.15 1.19 61.8 29.5 31 42.1 0.15 1,04 66.6 26.6 32 58.3 0.25 1.22 101.3 33.6 33 52.7 0.23 1.17 89.8 31,0

34 54,4 0.13 1.10 123,2 24.1 35 57.9 0.15 1.14 136.7 24.6 36 56.8 0.15 1,08 135.1 24.3 37 61.7 0.20 1.51 108,4 35,2 38 53.5 0.17 1.26 91.6 31.6 39 44,4 0.16 1,08 75.6 26.1 40 50,4 0.16 1,03 82,2 31,0 41 67.3 0.28 1,54 104.5 43,4 42 88.6 0.36 1.77 156.7 50.1 43 378
(49.6) 178.8 0.59 4,55 302.7 106,4 44 303
(39.8) 190.2 0.61 4,55 337.4 107,2 45 378
(49.6) 207.4 0.57 4,53 367.1 117.2 46 506
(66.4) 159.2 0.48 3.24 278.4 91.2 47 443
(58.1) 162.1 0.64 3.17 278.5 94.6 48 39.6 0.09 0.63 93.0 17.3 49 37.5 0.09 0.59 91.8 15.9 fifty 31,0 0,07 0.53 66.0 14.6

51 34.1 0.15 0.93 51.8 22.5 52 36,2 0.14 0.95 60.3 21.7 53 35.9 0.16 1.01 52.1 24.8 54 34.3 0.13 0.75 65.0 18.3 55 33.1 0.13 0.65 63,2 17.4 56 34.5 0.10 0.63 73.9 16,2 57 31.3 0.11 0.51 66.7 14.8 58 23.1 0,07 0.51 42.7 12.5 59 21.7 0.08 0.48 41.8 11.2 60 21,4 0,07 0.46 37.1 12,4 61 28.7 0.14 0.77 42.8 19,2 62 31,0 0.16 0.78 51,2 19.0 63 27.8 0.16 0.71 43,4 17.9 64 15.9 0.09 0.46 23.5 10.8 65 15.1 0.08 0.49 20,2 11.2 66 87
(11.4) 26.6 0.15 0.78 38.3 18.5 67 41.0 0.12 0.83 72.3 23.3 68 34.3 0.11 0.76 60.9 19,4 69 35.3 0.09 0.75 62.8 19.9 70 46.6 0.16 1,03 85.6 25.6 71 47.6 0.18 0.97 94.6 24.1

72 18.1 0.09 0.46 28.3 11.6 73 18.0 0.10 0.48 32.8 9.9 74 112
(14.7) 27.1 0.13 0.68 47.3 15,5 75 109
(14.3) 30.7 0.14 0.70 54,4 17.3 76 fifty
(6.6) 27.7 0.14 0.70 50,0 15.4 77 54
(7.1) 15.8 0.06 0.40 25.6 9.9

Bath fabric produced with paper pulp of southern varieties and 10% microfibre was 21% stronger than the control sample with the same softness (Figure 19). Based on the latter result, the microfibre web should be softer than the control sample if extensibility is reduced by stiffer creping, calendaring, embossing, and so on. From figure 20 it can be seen that microfibre lyocell has an exceptional ability to achieve low paper density at acceptable levels of elongation and softness.

From figure 21 it can be seen that the addition of microfibre lyocells in the CWP method increases the volume at different paper weights and tensile strengths. This is an unexpected result due to the fact that the specialist cannot expect an increase in volume from finely divided inclusions. This result is not observed in other methods, for example, a fabric creping method, where the fabric structure is formed in vacuum before applying an American drying apparatus to the drying cylinder.

Microfiber provides advantages to both the paper pulp of the southern grades and paper pulp of the highest level of quality (soft wood of the northern grades and eucalyptus), but the paper pulp of the southern grades to a greater extent.

Microfiber significantly increases the strength and elongation of fabrics with low paper density. The high fiber density provided by microfiber creates a very uniform network. Although most of the trends characteristic of microfibre observed in the study of hand linen were confirmed for creped fabric, the great influence of microfibre on elongation and modulus was unexpected. See Figures 22-26.

The volume, strength and opacity provided by microfibre makes it possible to reduce paper density, which is not achieved in the case of wood pulp. Elongation increases from 250 g / 3 in at 10 lbs / foot of sheets (32.8 g / cm at 16.3 g / m ² ) to 400 g / 3 in at 8 pounds / foot of sheet (52.5 g / cm at 13.0 g / m ² ) by adding 20% microfibre and CMC / WSR composition. A web with a density of 5.2 lbs / stack of sheets (8.5 g / m ² ) was obtained at the same extensibility as a control web with a density of 10 lbs / stack of sheets (16.3 g / m ² ) with the same combination of 20% microfibre and CMC / WSR, and provides more durable wood pulp.

Microfibre in the towel increased wet tensile, wet / dry ratio and SAT absorption capacity. This had consequences in the form of a higher level of softness of the towel or rag. The wet / dry ratio for one sample increased from about 20 to 39% with the addition of 20% microfibre. Microfiber modified the SAT / wet strength curve.

Lyocell 217 CSF had an unacceptable level of flocculants and nucleoli. Therefore, 400 CSF fiber was not used, and 40 CSF microfibre was used in the remaining tests. The 40 CSF microfibers were dispersed uniformly and it was found that the 217 CSF microfibers could be dispersed after passing through a conical mill not charged for 20 minutes. In the 217 CSF process, microfiber was reduced to 20 CSF.

Microphotographs of Bauer McNett fractions (see Figures 3, 4, and 5-9) suggest that half of the fibers in 40 CSF lyocells are not disintegrated. The consequence of this observation is that the results obtained in this test can possibly be obtained with half levels of addition, if the method continues until the fibrillation of 100% fibers.

The adhesion of the American dryer is slightly less in the case of microfiber paper pulp. The height of the dam in the headbox is increased due to less possibility for drainage, but can be controlled by the action of increased vacuum.

Strong effect on elongation / modulus

Figures 22, 23 and 24 show noticeable microfiber effects. Microfiber increases the elongation and elongation of the web. For example, the fabric base of a bath sheet with a density of 12 pounds / foot of sheets (19.5 g / m ² ), produced with 100% wood pulp, includes 40% softwood of southern varieties and 60% of hardwood of southern varieties. If 20% microfibre is added, the elongation increases by 48%, but the modulus increases only by 13%. A slight increase in module results from a significant increase in elongation of the web. MD elongation increases from 24.2 to 30.5%, and CD elongation increases from 4.2 to 6.0%. Microfibers give an advantage to the paper pulp of the southern grades and paper pulp of the highest level of quality (soft wood of the northern grades and eucalyptus), but a greater advantage is given to the paper pulp of the southern grades. This was demonstrated by comparing the “theoretical” elongation, defined as

(speed of the American dryer / bobbin speed - 1) · 100.

The theoretical MD elongation in this study was (100/80 - 1) · 100 = 25%. Here, the definition is the amount of stress required for easy exit creped canvas. It is possible to obtain an actual elongation higher than theoretical elongation, since an uncreated web also has a small elongation. Southern pulp in this example has an elongation of 24.2%, slightly below theoretical. In southern paper pulp or paper pulp of the highest quality level, MD elongation has a high value of 31-32%. The advantages provided to the paper pulp of the southern grades are greater, since its initial characteristics are much lower.

Figure 24 shows the change in elongation obtained by microfibre. Microfibre increases the extensibility in slightly ground tissue paper pulps, but the extensibility decreases in the paper pulp for a towel, where a larger percentage of the pulp is ground. The latter result is consistent with hand webs, but a large increase in extensibility in low density fabrics is unexpected and not observed in hand webs. Note that 20% of microfibre in handcloths with non-ground soft wood of the southern varieties does not lead to higher extensibility.

Paper weight reduction

Microfiber has the potential to significantly reduce paper density. Figures 25 and 26 show two examples in which paper density is reduced by 25 and 40-50%, respectively. In the first case, the base of the web with a density of 10 pounds / foot sheet at 255 g / 3 inches GMT (16.3 g / m ² at 33.5 g / cm) was reduced to a density of 8 pounds / foot sheets at 403 g / 3 inch GMT (13.0 g / m ² at 52.9 g / cm) with the introduction of 20% microfiber and a mixture of CMC / additive that increases the strength in the wet state. The wet / dry ratio was 32%. A sample with a density of 8 pounds / foot of sheets and 403 g / 3 inches (13.0 g / m ² with 52.9 g / cm) was 58% stronger than a control sample with a density of 10 pounds / foot of sheets (16, 3 g / m ² ), however, the fracture modulus increased by only 23%. Opacity and molding were good. In the second case, the base of the web with a density of 10 pounds / foot of sheets at about 400 g / 3 inches (16.3 g / m ² at about 52.5 g / cm) was reduced to a level of 5.2 pounds / foot of sheets (8.5 g / m ² ) with the same extensibility, using the same method as in the first case. Canvases with a density of 8 lbs / foot sheets (13.0 g / m ² ) have good uniformity. A web with a density of 5.2 pounds / foot of sheets (8.5 g / m ² ) had some openings, but the openings were caused by the limitations of the inclined template on PM 1 than by the fiber's ability to achieve good fiber distribution. A web with a density of 6 pounds / foot of sheets (9.8 g / m ² ) with good uniformity and extensibility is a significant achievement on the currently available prototype machine. A sickle shaped cutter can be suitable for even lower densities that cannot be achieved with 100% wood pulp. While such low densities may ultimately not be applied, this demonstrates the extent to which microfiber greatly affects the integrity of the fabric structure of the fabric.

Towel Properties

Microfiber can improve towel strength when wet, wet / dry ratio, and SAT absorption capacity. The base of the canvas with a density of 15 pounds / foot of sheets was obtained from 100% wood pulp paper pulp, which includes 70% soft wood southern varieties and 30% hard wood southern varieties. A traditional wet strength kit of 4 lbs / ton CMC and 20 lbs / ton Amres 25HP (2 kg / m ton and 10 kg / m ton) was used. The two control rolls had dry elongation of 2374 and 2400 g / 3 in. GMT and a wet CD ratio of 303/1705 = 18% and 378/1664 = 23%. The composition of the paper pulp was changed to 80% wood pulp and 20% cellulose microfibers, and the paper density of the product was kept at 15 pounds / foot sheets (24.4 g / m ² ). The volume increased, the opacity increased, the fracture modulus decreased 19%, and the tensile strengths in the dry state decreased to 2013 and 2171 g / 3 inches (264.2 g / cm and 284.9 g / cm). The wet / dry CD ratio on these two rolls increased to 506/1305 = 39% and 443/1545 = 29%. The absorption capacity of the SAT increased by 15%. The SAT absorption capacity and wet strength are usually inversely related, so the fact that microfiber increases both values means that the SAT / wet strength curve shifts positively. The selected results are presented graphically in figures 27 and 28 .

Without the need to be connected with any theory, it is assumed that the above results are the result of a microfiber network formed by microfiber. Figure 29 is a micrograph of a creped web without microfiber, Figure 30 is a micrograph of a corresponding web with 20% milled lyocell. From figure 30 it can be seen that the microfiber greatly enhances the formation of a fiber network in the web even at low masses because of its extremely high density of fibers.

Table 10 presents the FQA measurement data for various lyocell pulps. Even though it is likely that many microfibers are not visible, some trends can be seen on the fibers that are observed. Unmilled lyocell has a very uniform length, a very small number of fine-grained particles and is very linear. Pulverization reduces the fiber length, generates “fine particles” (which are different from the fine particles of traditional wood pulp) and makes the fibers curly. A comparison of milled to 4 mm with milled to 6 mm suggests that the initial fiber length within a certain range may not be essential for the final fiber length, since most of the original fibers will be split into shorter fibers. A length of 6 mm is preferred over 4 mm, since the fiber should avoid the additional processing step of cut short fibers from tow. Typical conditions for fibrillated lyocell are low concentration (0.5-1%), low intensity (which is determined by traditional pulverization technology) and high energy (possibly 20 HPday / ton). High energy is desirable if regenerated cellulose is fibrillated, as it may take a long time at low energy. A concentration of up to 6% or greater may optionally be applied, and a high energy input may be applied, possibly 20 HPD / ton or more.

Another result of Table 10 is that CSF lyocell 217 readily degrades to 20 CSF after re-passing through a conical mill not charged for 20 minutes. The CSF pulp 20 is uniformly dispersed in contrast to the CSF pulp 217.

Mechanism

Without the need to be connected with any theory, the mechanism of microfiber operation, as it seems, is its ability to significantly improve the uniformity of the network with an extremely high surface area. Several observations can be linked together to support this hypothesis: lyocell weakness, excellent strength, resulting in hand and tissue webs, and interactions with ground and ground wood pulp.

Unmilled lyocell is very weak in itself and even highly milled lyocell approaches close to the strength potential of wood pulp (8-10 km). Alpha cellulose in lyocell and fiber morphology appear to increase strength through a very high number of weak bonds. A high fiber concentration provides more bonds between wood fibers when added to the fabric. Pulp of southern varieties in general and pine, in particular, has a low fiber density, which requires higher bond strength than pulp of the highest quality level for a given strength. Southern softwood can also be difficult to form, leading to islands of unbound flocculants. Microfiber can weave flocculants to improve network uniformity. This microfiber ability becomes more pronounced as paper density decreases. A strong effect on the strength is not observed in hand webs with a high paper density, since there is a sufficient amount of wood fibers to fill the canvas.

INDUSTRIAL APPLICABILITY

Fibrillated lyocell is expensive relative to the paper pulp of southern varieties, but it offers potential opportunities that cannot be obtained by another method. Fibrillated lyocell fibers at relatively low levels of addition can enhance southern pulp at a competitive price relative to top-quality pulp.

Additional examples

Additional typical configurations include a three-layer product for the face, which includes two outer layers with exceptional softness, and an inner layer with strength in the wet state, and possibly a higher level of strength in the dry state than the outer layers. The product is made by combining cellulose microfibers and appropriate reagents to impart desired properties. It may be possible to achieve exceptionally low paper weights when obtaining a product with good strength.

Microfibers provide a huge surface area and network uniformity due to the extremely high fiber density. Network quality leads to higher wet / dry tensile properties.

Absorbency characteristics (speed and capacity) are attributed to the structure with smaller pores created by microfibers. There may be a more optimal addition rate, where capacity and other benefits are realized without speed reduction.

Southern fabric pulp bath fabric

A fabric base was made for a bath sheet with a density of 12 pounds / foot of sheets (19.6 g / m ² ) with 100% wood pulp, including 40% softwood of southern varieties and 60% of hardwood of southern varieties. Two rolls were produced with tensile strengths of 384 and 385 g / 3 inches GMT (50.4 and 50.5 g / cm) and fracture moduli of 37.2 and 38.2 g /%. The composition of the pulp was changed to 80% of wood pulp and 20% of cellulose microfibers. Two rolls with tensile strengths of 584 and 551 g / 3 inches GMT (76.6 and 72.3 g / cm) and fracture moduli of 42.7 and 42.9 g /% were produced. Elongation increased by 48%, but the modulus increased only by 13%. Low module growth arose from a significant increase in blade elongation. MD elongation increased from 24.2 to 30.5%, and CD elongation increased from 4.2 to 6.0%. Southern pulp in this example had a 24.2% elongation, slightly below theoretical. The pulp of the highest quality level in Example 1 yielded about 27% MD elongation. In southern paper pulp or paper pulp of the highest level of quality, the MD elongation is high, 31 - 32%. The advantages provided to the paper pulp of the southern grades are greater, since its initial characteristics are much lower.

Microfibers may be more favorable in fabric creped processes than in conventional air drying processes that require high permeability. The reason is that microfibers may tend to block the pore structure of the web, so that the air flow should be reduced in the traditional TAD method of air drying, but this is not a problem with wet pressing / creping methods in which the web is dehydrated by densification. One way to enhance the benefits of microfiber is to reduce paper density, but volume can then be a problem for certain products. Microfibre in combination with papermaking processes that form the web can be particularly beneficial for products with low paper weight with adequate volume. It should be noted that microfibers favorably alter the volume / strength relationship for CWP webs. The cellulosic substrate can be obtained by traditional methods (including TAD, CWP and their variants), known to specialists in this field. In many cases, the fabric creping techniques described in the following co-sent applications will be particularly useful: Patent Application Serial Number 11/678669, entitled “ Method of Controlling Adhesive Build-Up on a Yankee Dryer ” (from Attorney Book No. 2014 ; GP-06-1); patent application with serial number US 11/451112 (publication of US patent No. 2006-0289133), published June 12, 2006, entitled “ Fabric-Creped Sheet for Dispensers ” (according to the book of records of the lawyer No. 2015; GP-06-12); application serial number US 11/451111, published June 12, 2006 (publication of US patent No. 2006-0289134), entitled " Method of Making Fabric-creped Sheet for Dispensers " (according to the book of records of the lawyer No. 2009, GP-05-10); patent application with serial number US 11/402609 (publication of US patent No. 2006-0237154), published April 12, 2006, entitled " Multi-Ply Paper Towel With Absorbent Core " (according to the book of records of the lawyer No. 12601; GP-04-11) ; patent application with serial number US 11/151761, published June 14, 2005 (publication of US patent No. 2005/0279471), entitled " High Solids Fabric-crepe Process for Producing Absorbent Sheet with In-Fabric Drying " (according to the book of records of the lawyer 12633; GP-03-35); US Application Serial Number 11/108458 published April 18, 2005 (US Patent Publication No. 2005-0241787) entitled “ Fabric-Crepe and In Fabric Drying Process for Producing Absorbent Sheet ” (Advocatement Record Book 12611P1; GP-03-33 -one); US application serial number 11/108375, published April 18, 2005 (US Patent Publication No. 2005-0217814), entitled “ Fabric-crepe / Draw Process for Producing Absorbent Sheet ” (from Attorney Record Book No. 12389P1; GP-02-12- one); US application serial number 11/104014, published April 12, 2005 (US Patent Publication No. 2005-0241786), entitled “ Wet-Pressed Tissue and Towel Products With Elevated CD Stretch and Low Tensile Ratios Made With a High Solids Fabric-Crepe Process ” (according to the lawyer's record book 12636; GP-04-5); US Application Serial Number 10/679862 (US Patent Publication No. 2004-0238135), published October 6, 2003, entitled “ Fabric-crepe Process for Making Absorbent Sheet ” (Advocatement Record Book 12389; GP-02-12); US Provisional Application Serial Number 12/033207, published February 19, 2008, entitled “ Fabric Crepe Process With Prolonged Production Cycle ” (from Attorney Records 20216; GP-06-16); and provisional US patent application serial number 60/808863, published May 26, 2006, entitled “ Fabric-creped Absorbent Sheet with Variable Local Basis Weight ” (from Attorney Record Book No. 20179; GP-06-11). The applications indicated immediately above are especially significant for the selection of equipment, materials, processing conditions, and so on, for products creped with a fabric of the present invention; and these applications are included in this description as a reference material.

The wet structure of the web can also be dried either at the beginning of thermal dehydration, air drying or forced air drying. Suitable rotary equipment for forced air drying is described in US Pat. No. 6,432,267 to Watson and US Pat. No. 6,447,640 to Watson et al.

Examples 78-89 for towels

Hand towels such as towels were obtained from paper pulp from soft wood / lyocell and tested for physical properties and to determine the effect of additives on the ratio of CD-extensibility in the wet / dry state. It has also been found that pretreatment of the pulp with a baking powder composition is surprisingly effective in increasing the ratio of CD extensibility in the wet / dry state of the product, making even softer products possible. Details are given below and are presented in table 11.

The wood pulp used in Examples 78-89, was a softwood unbleached sulfated pulp of southern varieties. CMC is the abbreviation for carboxymethyl cellulose, a dry strength resin that has been added 5 pounds / ton (2.5 kg / m-ton) of fiber. Also in these examples, a wet strength improver (WSR) was added; Amres 25 HP (Georgia Pacific) added 20 pounds / ton (10 kg / m-ton) of fiber (including lyocell content in the fiber weight). The baking powder composition (Db) used was of type C; the ion-pair baking powder composition as described above was applied as 10% active and added based on the weight of the paper-forming fiber obtained through the pulp, excluding the lyocell content.

The CMF used was a 6 mm × 1.5 denier lyocell fiber, which was ground to 40 ml CSF before adding it to the pulp.

Next, the procedure was carried out as described below:

1. The pulp was pre-soaked in water before disintegration.

2. The pulp for samples 79, 81, 83, 85 and 86-89 was obtained by adding a disintegrant in the quantities indicated for the British disintegrator, then adding a pre-soaked dry preform to approximately 3% concentration and disintegration.

3. If the grinding of the mass is indicated in table 11, the pulp was divided in half; half of the pulp was concentrated to grind the mass, washed for 1000 rpm and re-diluted to 3% with filtrate.

4. The pulp halves were re-combined in a beaker and, with vigorous stirring, AMRES resin was added to increase wet strength. After 5 min, CMC was added. Then, after another 5 minutes, the pulp was diluted and a hand canvas was obtained; 0.5 g of the canvas was pressed at 15 psi / 5 min (1.0 bar / 5 min), dried on a drum dryer and cured in an air oven with forced drying at 105 ° C / 5 min.

5. The pulp for samples 78, 80, 82, 84 was obtained through the stages indicated above, passing a baking powder, and sometimes without grinding, as indicated in table 11.

6. For examples containing 20% CMF, CMF was added to softwood before adding WSR / CMC.

The effect of pre-treatment of softwood pulp with baking powder can be seen in figure 31 . The wet / dry stretch ratio is significantly increased both by the addition of CMF and by pre-treatment with baking powder. In some cases, the wet strength remains substantially constant, while the dry strength decreases. The dry strength of towels is often determined by the required wet strength, which leads to products that are relatively inflexible. For example, a towel with a 25% wet / dry stretch ratio can have a dry strength substantially greater than desired in order to satisfy wet strength needs. Grinding the mass is usually required to increase the strength, which reduces the volume and absorbency. An increase in the wet / dry stretch ratio from 24 to 47% makes it possible to reduce dry stretch by almost half. The lower modulus at a given stretch provided by the CMF also contributes to a better hand feel (Figure 32). Baking powder to some extent reduces the volume in the tested samples (Figure 33).

In industrial processes, it is preferable to pre-process the incoming stream of pulp-forming paper-forming fibers of the machine pool in order to increase efficiency, as noted in the simultaneously filed US patent application No. 60/850681, published October 10, 2006, entitled “ Method of Producing Absorbent Sheet with Increased Wet / Dry CD Tensile Ratio ”(according to the lawyer's record book No. 12645; GP-06-13), which is included in this description above; as can be seen in FIG. 34. In a typical application of the present invention, a baking powder was added to the pulp in a pulper 60, as shown in FIG. 34, which is a block diagram schematically illustrating the supply of pulp to a paper machine. Baking powder was added to the pulper 60, while the fiber at any concentration from about 3% to about 10%. The mixture was then pulped after adding a disintegrant for 10 minutes or more before adding a wet strength resin or a dry strength resin. The fiber in the pulp was diluted, usually to a concentration of 1 percent or so, and fed further into the machine pool 50, where other additives can be added, including a stable resin that increases wet strength and a resin that increases dry strength. If necessary, a resin that increases the strength in the wet state and a resin that increases the strength in the dry state, in the pulper, or the inlet stream or the outlet stream of the machine pool, that is, 64 or 66, can be added; however, they must be added after the baking powder, as noted above; and the dry strength resin is preferably added after the wet strength resin. The pulp can be pulverized and / or enriched before or after it enters the machine pool, as is known in the art.

From the machine pool 50, the pulp was then diluted to a concentration of 0.1% or about and further fed into a headbox, such as headbox 20, through a mixing pump 68.

The opacity of the fabric base of the canvas

Using a paper machine of the type shown in FIG. 18, fabric web bases of various paper weights were obtained using fibrillated regenerated cellulose microfibre and recycled paper-forming fiber obtained through pulp. TAPPI opacity was measured and correlated with paper density as shown in Figure 35 , which is a graph of TAPPI opacity versus paper density for 7 and 10 pound web webs (3.2 and 4.5 kg) having the formulations shown on the figure.

From Figure 35 it can be seen that large increases in opacity, typically in the range of about 30-40% or more, are more easily achieved by using fibrillated regenerated cellulose microfiber. Paired with the strength gain observed by the present invention, it is thus possible according to the invention to provide high quality fabric products using much less fiber than in the case of traditional products.

While the invention has been described in detail, modifications within the scope of the invention will be readily apparent to those skilled in the art. In view of the aforementioned discussion, essential information from the prior art and references, including those discussed above in connection with the prior art and a detailed description of simultaneously filed applications, all of which are incorporated by reference in their entirety, further description is deemed unnecessary.

Claims (41)

1. An absorbent cellulosic fabric comprising from about 99 to about 65 wt.% Pulp pulp-derived paper-forming fibers and from about 1 to about 35 wt.% Fibrillated regenerated cellulose microfiber obtained from a solution of cellulose with dissolved cellulose, including a solvent selected from ionic liquids and N-oxides of tertiary amines, where the microfiber has a CSF value of the degree of grinding of less than 100 ml, a weighted average diameter of less than 1 μm, a weighted average length of less than 400 km and fiber density of more than 2 billion fibers / gram. 2. The absorbent cellulosic fabric according to claim 1, where the ionic liquid is selected from the group consisting of imidazolium salts dissolving cellulose; pyridinium salts dissolving cellulose; pyridazinium salts dissolving cellulose; pyrimidinium salts dissolving cellulose; pyrazinium salts dissolving cellulose; pyrazolium salts dissolving cellulose; oxazolium salts dissolving cellulose; 1,2,3-triazolium salts dissolving cellulose; 1,2,4-triazolium salts dissolving cellulose; thiazolium salts dissolving cellulose; piperidinium salts dissolving cellulose; pyrrolidinium salts dissolving cellulose; quinoline salts dissolving cellulose; and isoquinolinium salts dissolving cellulose. 3. The absorbent cellulosic fabric of claim 1, wherein the absorbent fabric has an absorbency of at least about 4 g / g, and the fibrillated regenerated cellulosic microfiber has a weight average diameter of less than 0.5 μm, a weighted average length of less than 300 μm, and a fiber density more than 10 billion fibers / g. 4. The absorbent cellulosic fabric of claim 1, wherein the absorbent fabric has an absorbency of at least about 4.5 g / g. 5. The absorbent cellulosic fabric of claim 1, wherein the absorbent fabric has an absorbency of at least about 5 g / g. 6. The absorbent cellulosic web according to claim 1, wherein the absorbent web has an absorbency of at least about 7.5 g / g. 7. The absorbent cellulosic web according to claim 1, wherein the absorbent web has an absorbency of from about 6 to about 9.5 g / g. 8. The absorbent cellulosic fabric according to claim 1, where at least a portion of the pulp obtained through the pulp of the paper-forming fiber is pre-treated with the composition of the disintegrant to obtain a web, and where fillers and disintegrants are selected and pretreatment with a disintegrant of cellulose obtained through the pulp of a paper-forming fiber, as well as the formation of the fabric controlled so that the canvas had a ratio of CD-extensibility in the wet / dry state of more than 30%. 9. The absorbent cellulosic fabric according to claims 1 to 8, in which the fibrillated regenerated cellulose microfiber has a weighted average diameter of less than 0.25 μm, a weighted average length of less than 200 μm. 10. An absorbent cellulosic fabric according to claims 1 to 8, in which the fabric further comprises an agent that increases wet strength, including carboxymethyl cellulose and polyamidamine-epihalohydrin, and a disintegrant composition comprising a nonionic amphiphilic compound and a quaternary ammonium compound, where the agent and amounts wet strength improver and disintegrant are selected so that the ratio of CD / wet elongations in the wet / dry state is more than 35%. 11. The absorbent cellulosic fabric of claim 9, wherein the fibrillated regenerated cellulosic microfiber has a fiber density of more than 50 million fibers / g. 12. The absorbent cellulosic fabric of claim 11, wherein the fabric further comprises a wet strength improver, including carboxymethyl cellulose and polyamidamine-epihalohydrin, and a disintegrant composition comprising a non-ionic amphiphilic compound and a quaternary ammonium compound, where the agent and the amount of the enhancing agent wet strength, and baking powder is selected so that the ratio of CD-extensibility in the wet / dry state was more than 35%. 13. The absorbent cellulosic fabric of claim 9, wherein the fibrillated regenerated cellulosic microfiber has a fiber density of more than 200 billion fibers / g. 14. The absorbent cellulosic fabric of claim 12, wherein at least a portion of the cellulosic pulp-forming paper-forming fiber is pretreated with a disintegrant composition to form a web, and where fillers and disintegrants are selected and pre-treating the pulp-disintegrant of the pulp-forming paper-forming fiber and forming the web controlled so that the canvas had a ratio of CD-extensibility in the wet / dry state of more than 30%. 15. The absorbent cellulosic fabric according to 14, in which the fabric has a ratio of CD-elongation in the wet / dry state between approximately 35% and approximately 60%. 16. The absorbent cellulosic fabric according to 14, in which the fabric has a ratio of CD-elongation in the wet / dry state of at least about 45%. 17. The absorbent cellulosic fabric of claim 14, wherein the fibrillated regenerated cellulosic microfiber has an average fiber width of less than about 4 microns. 18. The absorbent cellulosic fabric of claim 14, wherein the fibrillated regenerated cellulosic microfiber has an average fiber width of less than about 2 microns. 19. The absorbent cellulosic fabric of claim 14, wherein the fibrillated regenerated cellulosic microfiber has an average fiber width of less than about 1 μm. 20. The absorbent cellulosic fabric of claim 14, wherein the fibrillated regenerated cellulosic microfiber has an average fiber width of less than about 0.5 microns. 21. The absorbent cellulosic fabric according to claim 1, in which the fibrillated regenerated cellulose microfiber has an average fiber width of less than about 2 μm. 22. The absorbent cellulosic fabric of claim 14, wherein the average fiber length of the fibrillated regenerated cellulose microfibers is less than about 150 microns. 23. The absorbent cellulosic fabric of claim 14, wherein the average fiber length of the fibrillated regenerated cellulose microfibers is less than about 100 microns. 24. The absorbent cellulosic fabric of claim 23, wherein the fibrillated regenerated cellulosic microfiber has an average fiber width of less than about 2 microns. 25. The absorbent cellulosic fabric of claim 14, wherein the average fiber length of the fibrillated regenerated cellulose microfibers is less than about 75 microns. 26. The absorbent cellulosic fabric of claim 25, wherein the fabric further comprises a wet strength improver, including carboxymethyl cellulose and polyamidamine-epihalohydrin, and a disintegrant composition comprising a non-ionic amphiphilic compound and a quaternary ammonium compound, where the agent and the amount of the enhancing agent wet strength, and baking powder is selected so that the ratio of CD-extensibility in the wet / dry state was more than 35%. 27. A method of obtaining an absorbent cellulosic fabric, including:
(a) preparing an aqueous pulp with a fibrous mixture comprising from about 99 to about 70% pulp-derived paper-forming fibers, where the fibrous mixture also includes from about 1 to 30 wt.% fibrillated regenerated cellulose microfibers having a CSF value of less than more than 100 ml, a weighted average diameter of less than 1 μm, a weighted average length of less than 400 μm and a fiber density of more than 2 billion fibers / g, where regenerated cellulose is obtained from a solution of cellulose with dissolved cellulose, including a solvent selected from ionic liquids and N-oxides of tertiary amines,
(b) placing the aqueous paper pulp on a perforated base to form a structure of the fabric being formed, and at least partially dehydrating the structure of the fabric being fabricated; and
(c) drying the web structure to form an absorbent web. 28. The method of obtaining an absorbent cellulosic fabric according to item 27, where the fibrillated regenerated cellulose microfiber has a fiber density of more than 10 billion fibers / g 29. The method for producing an absorbent cellulosic fabric according to claim 27, wherein the fabric-dehydrated structure of the fabric is applied to a rotating cylinder and a fabric fixed thereto. 30. The method of obtaining an absorbent cellulosic fabric according to clause 29, where the fibrillated regenerated cellulose microfiber has a fiber density of more than 50 billion fibers / g 31. The method of producing an absorbent cellulosic fabric according to clause 29, in which the fibrillated regenerated cellulose fiber has a microfibre density greater than 100 billion fibers / g 32. A method of producing an absorbent cellulosic fabric according to any one of claims 27-31, comprising the additional step of pretreating part of the fiber mixture with a baking powder composition, where the formation of the fabric and pretreatment of the fiber are controlled and the fillers and disintegrants are selected so that the fabric has a CD-elongation ratio of wet / dry state more than 30%. 33. The method of producing an absorbent cellulosic fabric according to claim 32, in which the paper-forming fiber obtained through pulp is treated with a baking powder simultaneously with obtaining the fiber. 34. A method of obtaining an absorbent cellulosic fabric according to any one of paragraphs.27-31, in which the paper-forming fiber obtained through pulp is treated with a baking powder simultaneously with obtaining fiber. 35. The method of producing an absorbent cellulosic fabric according to claim 33, further comprising crushing a pulp of a paper-forming fiber obtained through a pulp, in which a paper-forming fiber obtained through a pulp is treated with a baking powder composition before grinding the mass of a paper-forming fiber obtained through a pulp. 36. A method of producing an absorbent cellulosic fabric according to any one of claims 27-31, further comprising crushing the pulp of the paper-forming fiber obtained through the pulp, in which the paper-forming fiber obtained through the pulp is treated with a baking powder composition before crushing the mass of the paper-forming fiber obtained through the pulp. 37. The method of producing an absorbent cellulosic fabric according to claim 33, wherein the paper-forming fiber obtained through pulp is pretreated with a baking powder before it is mixed with fibrillated regenerated cellulose microfiber. 38. A method of producing an absorbent cellulosic fabric according to any one of claims 27-31, wherein the paper-forming fiber obtained through pulp is pretreated with a baking powder at a concentration of more than 2%. 39. The method of producing an absorbent cellulosic fabric according to claim 27, in which the paper-forming fiber obtained through pulp is treated with a baking powder at a concentration in the range of from about 3 to about 8%. 40. A method of producing an absorbent cellulosic fabric according to any one of claims 27-31, wherein said fibrillated regenerated cellulosic microfiber has a fiber density of more than 200 million fibers / g. 41. The method of producing an absorbent cellulosic fabric according to any one of claims 27-31, further comprising introducing into the fabric an agent that improves wet strength, including carboxymethyl cellulose and polyamidamine-epihalohydrin, and a disintegrant composition comprising a nonionic amphiphilic compound and a quaternary ammonium compound, where the agent and the amount of wet strength improver and disintegrant are selected so that the ratio of wet / dry CD extensibility is greater than 35%.

Images