ES2267304T3 - COMPRESSED ABSORBENT FIBROSED STRUCTURES. - Google Patents

Abstract

The present invention provides compressed paper webs that maintain a substantial amount of their absorptive capacity and wet strength when compressed. The compressed webs bounce back to a portion of their uncompressed state when wetted. The present compressed webs allow more towels to be added to a dispenser without substantially sacrificing the absorbent capacity or the strength of the towels.

Description

Absorbent fibrous structures compressed

Field of the Invention

The present invention relates in a manner general to a procedure for the formation of structures based of fibrous and absorbent paper, such as hand wipes, tissues, cloths and the like, and more particularly refers to compressed and absorbent fibrous structures.

Background of the invention

Structures are well known in the art. Fibrous absorbents, such as hand wipes, wipes, tissues and similar, as well as various components for other absorbent and fluid handling materials. These structures can be formed by materials that allow them be absorbent, such that said structures absorb Typically, to varying degrees, liquids from one's own body or any other place. These liquids may include water, coffee, milk, cleaning products, oil, etc., and various body fluids, such as blood, urine, nasal discharges and Other body secretions. To make these structures fibrous, various natural pulp fibers may be useful of wood, as well as synthetic fibers.

Frequently, fibrous structures absorbents, such as hand wipes (usually designated "paper towels"), are wrapped around of some kind of inner cardboard tube. These internal tubes of cardboard, along with the wipes wrapped around them, they can be placed in various types of dispensing mechanisms to effects of allowing users to take a wipe from this roll, or several at once. The rolls of wipes can be perforated at various points in order to divide the rolls in their set in individual wipes. During the dispensation, a user can tear one or more wipes along the lines of drilling to make use of them. If the wipes are not perforated, some teeth can be arranged in the dispenser to Help break the roll into individual wipes.

Due to the bulkiness of the rolls of paper, for each of them there is only one number or a defined length of wipes, and thereby a number Defined drying uses. Usually, this number of Drying uses are designated as the number of drying of hands available.

The size of the paper rolls and, with it, the resulting number of hand drying, may be limited by the size of the dispensers in which the rolls should be housed. Most size roll wipes dispensers standard can accommodate a roll of paper towels with a diameter approximately between 8 and 9 inches (20.32-22.88 cm). Frequently, the consumption of paper wipes from the roll must be controlled and the Dispenser should be recharged frequently to prevent Finish the product.

Some paper towels, however, are can be arranged in a folded state, stacking multiple wipes one on top of the other. In these types of provisions, you can only Dispense a single wipe at a time. Frequently, as in the case of roll wipe dispensers, dispensers in which stacked and dispensed folded wipes may have a limited capacity and, similarly, must be controlled and recharge frequently.

The termination of the wipes occurs when the wipes present in a dispenser have been spent and the corresponding manager has not yet filled in the dispenser with a new or additional supply of wipes. The termination of Wipes may be one of the most frequent complaints of end users of paper towels. The prevention of wipe termination may require more frequent visits by the manager or the addition of more wipes in the dispenser. The first solution is not desirable with great probability by end users of wipes or by entities that acquire the wipes for final use, since a increase in the visits of the manager obviously increases Labor costs It seems that the second solution is not yet it has been possible to apply due to the fixed size of the dispensers and to the thicknesses of the usual wipes.

Even in the case of rolls of frequently wipes, the rolls of wipes used Currently they can lead to significant losses. To avoid Towels are finished, it is often necessary to replace a roll of wipes before using the entire roll completely. It is possible that the amount of wipes left in the roll does not justify that the remaining wipes of the roll and, thus, the wipes are usually discarded remaining, still unused, together with the inner tube of the roll.

In general, it has been experienced that the more bulky, or thick, is a wipe, a handkerchief or a cloth paper, more absorbent and "soft" is. Although you are features are desirable and can be obtained through the formation of fibrous structures with greater thicknesses, thickness additional generates numerous disadvantages. For example, as the thickness of a wipe increases, the number or length of wipes that can be housed inside a standard dispenser and, with it, the number of drying uses.

Another disadvantageous consideration when using conventional size wipes is that there is a number determined by hand drying for each box of wipe rolls or for each box of folded wipes packages. From the point of view of transport costs (charter and transport materials it is expensive), and from the point of view of storage, it would be It is desirable to include more hand dryings in each box of wipes. In particular, the end user will need to store fewer boxes in its facilities if each box includes more hand-dried.

Also, when using roll wipes, the inner tube around which the wipes are wrapped should discarded. The more wipes that can be arranged in a roll, less frequently such internal tubes will be discarded. Whether you can roll an additional number of wipes to form a roll, conservation and recycling efforts can be increased, allowing each inner tube to be used for a period of longer time.

The present invention addresses some of the needs described above, and discloses an improvement in the termination of the wipes and in excess waste, and can provide more wipes inside a wipe dispenser than standard size.

US Patent No. 5,779,860, to Hollenberg et al. , Whose owner is commonly the beneficiary of the present invention, refers to a product and a method that uses compression techniques to increase the density and reduce the thickness of various sheet elements, such that space-saving wipes of the type described herein can be obtained. However, the absorbent structures described in said patent are compressed until structures with a thickness less than about 50% of the thickness of the original uncompressed structure are obtained. In other words, the non-compressed laminar elements of Hollenberg and others are compressed to increase their densities by at least about 50%. For example, an uncompressed sheet element with a density of approximately 0.2 grams per cubic centimeter can be compressed such that its density increases to approximately 0.3 grams per cubic centimeter or more. Particularly, the laminar elements containing high performance pastes, such as bleached chemothemomechanical pulp, can be compressed to these levels keeping their structure and strength wet. In fact, when saturated with water, the density of these compressed laminar elements decreases by approximately 20% or more. As described herein, the laminar elements according to the present invention provide some of the advantages of the laminar elements described in Hollenberg et al. , But are formed by different materials and by different procedures.

Characteristics of the invention.

The present invention discloses a procedure for the formation of a laminar element based on absorbent and compressed paper according to claim 1.

According to the present invention, they are achieved some advantages compressing a paper laminar element that It has a temporary or permanent wet resistance. He resulting paper sheet element may allow the addition of a longer length of wipes in a roll of wipes (or the adding a larger number of wipes in a pile of wipes folded), without substantially increasing the diameter of the roll (or the thickness of the pile of wipes). A larger number of sheets in a Roll (or more wipes in a stack of folded wipes) can lead to fewer refills and refills of the roll (or of the folded wipes) for the end user. A smaller number of Rolls per box and a reduced box size can lead to scrap of a smaller number of internal tubes and boxes of transport. The invention can also allow the transport of more wipes in the same truck or placing more wipes in a standard transport compartment.

A compression force is applied to the element paper sheet to obtain a paper sheet element compressed with a certain reduced thickness. The amount of compression applied to the paper sheet element can be expressed as a "thickness compression ratio", as defined in this document. The compression ratio of thickness is between about 0.1 and about 0.5 in order to meet the requirements of this invention.

In addition, compressed laminar elements according to the present invention preferably have a capacity of water absorption, at least, of approximately 70% of the water absorption capacity of the same sheet element before its compression, desirably, at least, of approximately one 80%, and more desirably, at least, of approximately one 90%

It has also been observed that the elements compressed laminar according to the present invention "return elastically ", or expand, to some extent when wet. This expansion may allow you to get wet after tablets,  the laminar elements recover from approximately 60% up to approximately 150% of its original uncompressed thickness. According to the invention, paper based laminar elements tablets are able to recover at least 70% of their original thickness when saturated with water.

The sponge-like action of these elements Compressed laminar allows them to maintain characteristics of absorption similar to those of the original laminar element no compressed. However, since the laminar elements are tablets, you can accommodate a larger number of wipes in a single dispenser, whether said dispenser is designed to accommodate folded wipes like wipes arranged around a tube internal roll. In any case, using the elements Compressed laminar according to the present invention can be reduced the frequency of control of the supply of wipes. Further, using the present invention can also reduce the frequency of excessive waste.

The compression required herein invention can be accomplished by various procedures different. For example, an additional stage of calendering or, alternatively, a higher pressure may be applied to the original calendering rollers used in a manufacturing process of the fibrous structure absorbent.

Various fibers can be used to form the laminar elements according to the present invention. For example, wood pulp fibers can be used in 100% amounts. Alternatively, mixtures of pulp fibers of wood and other types of fibers, including various fibers synthetic, such as meltblown and extruded fibers (Meltblown and Spunbonded). In addition, other types of fibers and filaments to provide the desired elasticity to laminar elements. For example, fibers can be used produced by chemical, thermal and mechanical processes of paste reduction and by thermal and mechanical processes of paste reduction, or through other paste reduction processes of high performance, as well as curly fibers produced by various procedures, such as high consistency refining,  and internally crosslinked fibers.

The laminar elements used to form the absorbent and compressed fibrous structures according to the The present invention can be produced according to the methods of through air drying without creping, strong wet creping or light dry creping, described herein, being able to obtain favorable products of compressed wipes that have acceptable and desired characteristics by the consumer, such as its absorption capacity and its softness.

These and other characteristics, aspects and advantages of the present invention will be better understood by making reference to the following description and the claims attached.

Detailed description of the preferred embodiments

Next, detailed reference will be made to the embodiments of the invention, one or more examples of which They are set out below. All examples are provided to title of explanation of the invention, not by way of limitation. From In fact, those skilled in the art will understand that they can take make various modifications and variations in the present invention without departing from the scope of it. For example, the features illustrated or described as part of an embodiment they can be used in another embodiment, giving rise or another additional realization Thus, it is intended that the present invention covers all modifications and variations that come in within the scope of the appended claims. Other objects, Features and aspects of the present invention are described in the following detailed description, or are obvious from the same. Those skilled in the art should understand that the This is a description of embodiments only by way of example, and that is not intended to limit the broader aspects of the present invention

In general, the present invention relates to a procedure for the formation of laminar elements tablets, useful for the formation of fibrous structures absorbents, such as paper towels and the like. In addition, the compressed laminar elements according to the present invention can be used in other absorbent applications, such as in diaper components, pads, feminine hygiene products, incontinence products and the like. Using the compressed laminar elements according to the present invention in the products mentioned above and in other products absorbent, thinner and less bulky products are put on consumer supply. These finest and least products bulky provide some advantages in terms of space of storage, dispensing space and, in case the consumer wear the absorbent product, in terms of more comfort

Despite being compressed, and contrary to what conventional knowledge, wipes and other absorbent structures formed according to the present invention they do not substantially lose their necessary absorption capacity at effects of acting as absorbent structures. In addition, the absorbent structures maintain desirable characteristics, such such as softness and other qualitative aspects.

The laminar elements can be made in various fibers, including various cellulosic fibers, such as natural wood pulps, together with various additional fibers, including fibers made from synthetic resins. The fibers useful for making the sheets according to the present invention they can be wet elastic fibers, which include various fibers High performance pasta, flax, milkweed, abaca, hemp, cotton or any other similar, which are wet elastic of natural form, or any modified wood pulp fiber chemically or physically. These pulp fibers may include fibers. crosslinked or curly, so that they have the ability to recover after deformation in its wet state, as opposed to non-elastic fibers, which may remain deformed and not recover after deformation in the wet state.

Desirably, the absorbent structure should be dimensionally stable enough for the laminar element does not crush when the laminar element contacts with the water Without this elasticity, the compressed laminar element it would be relatively useless for different applications absorbents considered by the present invention.

As is known in the art, various materials can be used to add additional wet strength to the resulting compressed absorbent structures. These wet strength agents are commercially available from a wide variety of sources, and some of them are generally described in US Patent No. 5,779,860 to Hollenberg et al . Any material that, when added to paper or fabrics, provides a wet strength ratio to dry strength greater than 0.1 is considered a suitable wet strength agent. Generally, these agents are classified as "permanent" or "temporary" wet strength agents. Permanent agents provide a product that retains more than 50% of its original wet strength after exposure to water for a period of at least five minutes; Temporary agents provide a product that retains less than 50% of its original wet strength after exposure to water for a period of five minutes. These agents, both permanent and temporary, are typically added to the pulp fibers in an amount of at least 0.1% by dry weight, and usually in an amount between about 0.1% and 3% in dry weight, referring to the dry weight of the pulp fibers.

The absorbent laminar elements according to the Present invention are performed by drying procedures by transverse air circulation without creping, strong creping in Wet or light dry crepe. After its formation, the elements Laminates according to the present invention are compressed by exercising on the same a certain force per linear inch (per 2.54 cm) while posing through one or more roller assemblies of calendering or supercalandering. Other ones can also be used. mechanisms other than calendering procedures of providing the necessary compression forces.

As used herein, the term "calendering" refers to a procedure for tissues  or nonwoven web elements that reduce their thickness and confers surface effects, such as a greater shine or softness. Generally, the procedure includes passing the tissue to through two or more heavy rollers, sometimes hot, at high clamping pressures

In US Pat. Nos. 5,779,860, of Hollenberg et al. , And 5,048,589, of Cook et al. , Methods for forming laminar elements dried by transverse air circulation without creping are described.

In these procedures, drying by transverse air circulation is used as shown in the figures of Cook et al . As described and shown in said patent, a laminar element is prepared as follows: (1) a paper pulp is formed with cellulosic fibers, water and a chemical disintegrant; (2) the paste load is deposited on a conveyor belt, forming a fibrous sheet element on the conveyor belt provided with holes; (3) the fibrous web is subjected to drying without compression to remove water from the fibrous web; and (4) the dry fibrous web is removed from the conveyor belt provided with holes. The procedure described in said document does not include creping and, therefore, is referred to as a cross-drying process of air without creping.

Typically, wipes prepared from of this drying process by transverse air circulation without creping they have relatively high levels of ability to absorption, absorption speed and resistance. Also, since the procedure does not present expensive stages of creping, the wipes produced by such a procedure have a cheaper production than composition crepe wipes and similar basis weight.

In US Patent No. 5,336,373, of Scattolino and others, a procedure that produces a non-sheet is described compressed using drum drying and that can be used in The present invention.

The thickness of the laminar elements before the compression according to the present invention is typically between approximately 0.005 inches (0.127 mm) and approximately 0.030 inches (0.762 mm). After compression, a compressed laminar element according to the present invention will have a thickness between approximately 50% and approximately 90% of its original thickness.

As used herein, "thickness" refers to the thickness of a sheet or element laminate. In the following examples, the thickness has been measured using an EMVECO model 200-A device with the following specifications: foot descent speed of pressure of 0.8 millimeters / second; pressure foot surfaces and parallel anvil within 0.001 millimeters, reading capacity repeated within 0.001 millimeters in zero setting or in scale calibrated; fixed face of smooth circular base (anvil) of one size which is in contact with the entire surface of the pressure foot in the zero position; 0-12.7 mm capacity; sensitivity of 0.025 mm, load of 2.0 kiloPascals; anvil surface of 2,500 square millimeters; and diameter of anvil of 56.4 mm.

Compressed laminar elements can be characterized by a certain compression ratio of thickness. As used herein, the "thickness compression ratio" is defined by the following equation:

\ frac {(\ text {element thickness uncompressed sheet} - \ text {sheet element thickness compressed})} {\ text {thickness of the laminar element no compressed}}

In the laminar elements according to the present invention, the compression ratio of the thickness is comprised between about 0.1 and about 0.5.

       \ newpage
    

In addition, the compressed laminar element can have sufficient absorption capacity to allow absorb liquids and act similarly to the same element laminate in uncompressed state. The absorption capacity is refers to the amount of liquid that can be absorbed by the paper laminar element. The absorption capacities described in this document they are defined according to the grams of water (or oil) absorbed by the absorbent structure divided by the weight in grams of the structure that absorbs water (or oil). The oil absorption capacity of a sheet indicates the volume internal recesses of the sheet. As the sheet is compressed, The internal hollow volume decreases.

The absorption capacity of the products of paper (its water or oil absorption capabilities) can determined by the following procedure. It is filled with water distilled (or oil) a container large enough to to hold water to a depth of at least 2 inches (5.08 cm). In addition to a stopwatch, a balance is used, for example the OHAUS GT480 balance described below. I also know use a cutting device, such as the one sold under the trade name TMI DGD of Testing Machines, Inc., of Amityville, New York, and a 4-inch by 4-inch mold (± 0.01 inches) in size (10.16 cm by 10.16 cm ± 0.25 cm). Samples of the size of the mold are cut and weighed dry to the nearest 0.01 gram. The stopwatch is activated when introduce the sample into the water (or oil) container, and leave soak for 3 minutes ± 5 seconds. At the end of time specified, the sample is extracted using tweezers and attached to a hanging clamp so that it hangs in a position in "diamond" shape in order to ensure the proper flow of fluid from the sample. In addition, the sample is hung for 3 minutes ± 5 seconds in a chamber with a relative humidity of 100% Then, releasing the clamp, the sample is dropped on the heavy plate. The weight is then recorded until the 0.01 gram closer.

Next, the capacity of Absorption of each sample as follows:

Capacity of absorption (g) = Wet weight (g) - Dry weight (g)

Obviously, the absorption capacity particular of a laminar element depends on a variety of factors, including its base weight and its composition. In this way, in the present invention laminar elements with a variety of absorption capacities, and generally depend on large measure of the capacity required for the application Desired finish for absorbent structures.

Typically, compressed laminar elements according to the present invention they will have an absorption capacity of water of at least approximately 70% of the capacity of water absorption of a non-compressed paper web composed of the same materials and the same procedure and with an identical base weight.

As used herein, "basis weight" refers to the mass per unit area and is expressed in grams per square meter or "g / m2". The base weight is measured by cutting a sample part of a sheet element and subjecting said sample to the following procedure. A balance with sufficient capacity and sensitivity is used to weigh up to about 0.001 grams for samples weighing less than about 10 grams, and up to about 0.01 grams for samples weighing approximately equal to or greater than 10 grams. For example, a scale that can be used is marketed under the trade name OHAUS GT210 of VWR Scientific Product of South Plainfield, New Jersey. The standard weights for a balance are between approximately 10 milligrams and approximately 100 grams. If a level is not supplied with the balance, a sealed glass vial can be used. The weighing container must be large enough to accommodate the sample without protruding from the edges of said container. Desirably, the minimum mold size for a single sample is 4.5 ± 0.1 inches (114 ± 3 mm) by 4.5 ± 0.1
inches (114 ± 3 mm). If several smaller samples are used, any mold of known size will be appropriate. The ruler will graduate in increments of 0.1 inches, or 1 mm.

The test samples obtained from the laminar elements must not present creases, wrinkles or distortions of any kind. Desirably, all samples should have a minimum surface area of at least 20 inches square (130 square centimeters), or should be taken in different points a number of smaller samples cut in mold with a minimum total surface area of at least 20 inches square (130 square centimeters). Then they must Weigh and record all samples.

Next, the base weights are calculated determining the surface of the sample or samples in inches square (6.45 cm2). Subsequently, the sample weight or Samples, measured in grams, are divided by the surface. This value multiply by a factor in order to obtain the units desired. Conversion factors to multiply by (weight / surface) are as follows:

g / m2 = 1550 g / yards2 = 1296 pounds / 2880 ft2 (pounds / ream) = 914.31 ounces / yard2 = 45.72

Before testing the elements Laminates according to the present invention, the sheets were conditioned  up to ASTM relative humidity conditions of 50% ± 2% and a temperature of 72ºF ± 2º (22.2ºF ± 1.1º) for at least minus 24 hours

Another feature of the laminar elements according to the present invention is its ability to recover in a majority proportion the thickness or bulkiness they had before of compression. In other words, the laminar elements are capable of expanding after being exposed to water, and will return, by at least 70% of its wet thickness not original tablet, and desirably at least about at 80% of its original non-compressed wet thickness. Thickness in wet refers to the thickness of a particular laminar element after be submerged in water for 30 seconds and then left hang for a minute to allow it to be removed from it excess of water.

In a particular example, a paper sheet with a basis weight of 22 pounds / ream of 2,880 square feet (37 g / m2), made according to drying process by transverse air circulation without crepe described above and from a paste load composed of 70% recycled fiber and 30% pine paste of Mobile obtained by the paper pulp mill Kimberly-Clark located in Mobile, Alabama. To the test the compressed laminar element (having reduced its compression thickness 22%) with this formulation in state wet with respect to the same wet laminar element not compressed, the evaluators of the characteristics of the elements laminar did not appreciate a difference statistically significant between compressed wipes and non wipes compressed in terms of overall quality, effectiveness drying, absorption speed or substantial smoothness.

In one trial, wipes were analyzed in various compression states. For example, a roll that, normally, it would be 800 feet (24,384 cm) in length in one state not compressed, it was compressed so that a roll of it diameter was 1,000 feet (30,480 cm) in length (an increase of 25%), and another roll of the same diameter was 1,200 feet (36,576 cm) in length (an increase of 50%). The average length of the uncompressed paper towels used for drying hands were 23.5 '' (59.7 cm), while the average length in the compressed paper towels (at a compression of 25%) were 24.7 '' (62.7 cm) and average length on paper towels tablets (at 50% compression) was 24.3 '' (61.7 cm).

Various procedures can be used to compress the laminar elements according to the present invention, and the The present invention is not limited to the use of any compression procedure in particular. As it is known in the technique, by passing the sheets through one or more rollers or jaws are compressed and smooth the surfaces of the materials of the sheet. Generally, the equipment used to apply the Compressive force are designated calenders or supercalanders. Obviously, the effect of calendering on a structure in particular depends on the temperature, the pressure applied and the duration of pressing, being able to vary these three factors to effects of obtaining the desired results of calendering.

When compressing the laminar elements according to the present invention, an additional calender can be used or, in an alternative, a higher pressure can be applied to the rollers originals of the calender used to produce the structure absorbent fibrous Alternatively, various can be used. calendering techniques, such as hot calendering or by steam, to produce compressed laminar elements absorbents

Alternatively, the laminar elements can be compressed using flat plate presses or fabric jaws used to soften and compact multi-layer cloth products, as disclosed in US Patent 5,399,412, to Sudall et al . Thus, the resulting sheets according to the present invention may have highly compressed surfaces and less compressed or uncompressed surfaces.

Generally, these compression procedures they are described as the application of certain force per linear inch (2.54 cm) on the paper laminar element, and are expressed in pounds per linear inch ("PLI") (178 g / cm). The "pressure of pinched "is another term used in this document, and it refers to the pressure applied in the calendering jaw. The pinch pressure is defined as the ratio between the force per linear inch and the width of the jaw formed between the rollers of calendering.

The following examples are intended to be only Examples of procedures to help understand this invention. The invention is not intended to be limited by same.

Examples 1-6

1 foot = 30.48 cm

In Examples 1-3, it is they compared roll wipes, produced by a procedure drying by transverse air circulation, in a non-state 800 ’tablet in a roll (example 1); in a compressed state 1,000 ’in a roll (example 2); and in a compressed state of 1,200 'in a roll (example 3). Example 2 is the same roll of example 1 that has been compressed to include 25% of feet additional, and example 3 is that same roll that has been compressed to include an additional 50% of feet.

       \ newpage
    

The laminar elements of the examples 1-3 were produced from a paste load that it contained 55% recycled Owensboro fibers, 28% pine from Mobile, 7% of recycled Fox River fibers and 10% of waste. The laminar elements had a basis weight of approximately 16 pounds / ream.

In examples 4-6, compared roll wipes of identical diameters (7.9 inches or approximately 20 centimeters), produced by a drying process by transverse air circulation without creped, in an uncompressed state of 425 ’on a roll (example 4); in a compressed state of 530 ’on a roll (example 5); and in a compressed state of 640 ’on a roll (example 6). Example 5 it is the same roll of example 4 that has been compressed to include an additional 25% of feet, and example 6 is that same roll that has compressed to include an additional 50% of feet.

Examples 4-6 occurred at from a pulp load containing 20% fibers recycled from Owensboro, 48% Mobile pine, 12% fiber Recycled from Fox River and 11% waste. The elements laminar had a basis weight of approximately 23 pounds / ream of 2,880 square feet (39 g / m2).

Tables 1-5 show various measurements taken on the laminar elements formed to from examples 1-6. The determinations of base weight, thickness per EMVECO and absorption capacities of Water / oil have been described above. An essay "in wet "refers to samples of laminar element that have been submerged in water for 30 seconds and then they have left hanging for 60 seconds for drying before being analyzed.

The "machine address" or "DM" is refers to the direction of surface displacement in formation on which the fibers are deposited during formation of a material. The "transverse direction of the machine", or "DTM" refers to the direction perpendicular to the address of the machine and contained in the same plane as this one.

The "fall" is a measure of stiffness or flexural strength of a tissue and is calculated by determining the bending length of a fabric applying the bending principle cantilever fabric by its own weight. Except in the size of the sample, the test to measure the fall is in accordance with the test ASTM D 1388 standard. To determine the fall, a FRL-Cantilever Bending Tester, model 79-10, from Testing Machines, Inc., of Amityville, New York. After conditioning as it is described herein, a tissue sample is cut 1 '' x 8 '' (1 '' = 2.54 cm) and slides on a surface horizontal at a speed of 4.75 '' (1 '' = 2.54 cm) per minute, in a direction parallel to the long dimension of the sample, and towards the edge of the horizontal surface of the meter. The sample is shifts until its leading edge protrudes from the edge of the horizontal surface. When the edge of the sample reach the edge of the knife, the meter switch turns off and the outgoing length is recorded from the linear scale of the measurer. This measurement is carried out when the tip of the sample descends by its own weight to the point where the line that joins the tip to the edge of the horizontal surface forms an angle of  41.5º with the horizontal surface. The more outgoing length, The lower the bending speed of the sample. In this way, the Higher values indicate a stiffer fabric. Fall stiffness It is expressed in centimeters and is calculated by multiplying the length of flexion in inches by 2.54.

The "Elmendorf Torn" is a measure of the force necessary to tear a sheet in a given address. It is calculated by dividing the tear load by weight base of the laminar element sample. The tear load measures the hardness of a material measuring the work necessary to propagate a tear when part of a sample is held by a clamp and an adjacent part is displaced by the force of a pendulum that It falls freely in an arc. The Elmendorf Torn of the elements laminar that determines the average force needed to propagate the tear starting with a groove cut in the material is measured as follows (higher numbers indicate greater strength required to tear the sample): the pendulum instrument Elmendorf type fall is equipped with a pendulum that presents a deep notch (hollow area) in the pendulum sector and clamps pneumatically activated These meters are marketed under the trade name LORENTZEN AND WETTRE BRAND, model 09ED, of Lorentzen Wettre Canada Inc., of Fairfield, New Jersey.

In addition to the meters, a cutter is used of samples capable of providing a sample of 63.0 ± 0.15 mm (2.5 ± 0.006 inches) by 73 ± 1 mm that is cut to no less 15 mm from the edge of the material, without folds, wrinkles, or distortions of any kind. The 63 mm length of the sample is arranged vertically on the tear meter. It adjusts the dialing the meter to the number of sample layers a tear and then the cutting lever is operated. The Sample is placed between the tweezers, with the edge of the sample aligned with the front edge of the tweezers. Then it close the clamps and cut a groove in the sample by operating The lever of the cutter knife. Then, the pendulum and placed in the initial position after moving a full swing travel. Subsequently, the value of torn, except if the tear line deviates more than 10 mm, in in which case a new trial is carried out. The results are recorded in grams. Tearing DTM is the tear force necessary to tear in the direction perpendicular to the direction of the machine; Torn DM is the necessary tear force to tear in the direction perpendicular to the transverse direction of the machine

Various trials of resistance, as indicated in the following tables. Particularly, the tensile strength was determined (peak loads), elongation (% stretch), AET (tensile energy absorption) in the breakage and energies of peak for the different laminar elements. Resistance to traction is the maximum tensile tension developed in a test sample before rupture in a tensile test carried out until the break under prescribed conditions, and it is the force per unit width of the test sample. He stretching or elongation is the maximum tensile strain developed in the test sample before the break in a test of traction carried out for a break under conditions predetermined, and expressed in percentage (100 times the ratio between increasing the length of the test sample and the length of original essay). The tensile energy absorption is the work done when a sample extends to breakage by traction under predetermined conditions, and is measured by the integral of the tensile stretch along the tensile strain, from zero to maximum strain, and it is expressed as energy per unit area of the sample of test. The essays are identified in the tables, indicating if they have been carried out for DM or DTM addresses and for wet or dry states.

The following test procedure was used. to carry out the various resistance tests on the sheets of paper. The equipment included a tensile test unit or constant speed of extension ("constant-rate-of-extension, CRE ") together with an appropriate load cell and system computerized data acquisition. An example of a CRE unit is sells under the trade name SINTECH 2, manufactured by Sintech Corporation, whose address is 1001 Sheldon Drive, Cary, North Carolina 27513. The type of load cell was selected depending on the traction meter used and the type of material rehearsed The selected load cell had interest values within the intervals recommended by the manufacturer between the values of the entire scale of the load cell. The cell of loading and data acquisition system, marketed under the trade name TestWorks ™, can also be obtained through from Sintech Corporation.

Additional equipment included powered jaws pneumatically, weight suspension brackets and a cutter precision samples. The jaws were designed for a load maximum of 5,000 grams, and can be obtained through the signature Sintech Corporation The weight suspension brackets included a flat square and an "L" shaped square. These squads they were inserted into the jaws during calibration or setting point. A precision sample cutter was used to cut samples within a width of 3 ± 0.04 inches (76.2 ± pm 1 mm) An example of sample cutter is marketed under the trade name JDC, of the firm Thwing-Albert Instrument Co., of Philadelphia, PA.

The tests were carried out in an atmosphere laboratory standard, at 23 ± 2ºC (73.4 ± 3.6ºF) and at relative humidity of 50 ± 5%. The two were established main addresses, machine address (DM) and the transverse direction of the machine (DTM) of the material. The samples had a width of approximately 3 inches (7.62 cm), and a length of approximately 4 inches (10.2 cm). The length of the sample was in the transverse direction or of the machine of the material tested, depending on whether the traction was measured in the machine or transverse direction, in order to select the direction of the length of the samples. Desirably, the length was cut approximately 1.5 inches (3.81 cm) longer that the separation of clamps used for the test, and the tested samples showed no tears or other defects, and they had parallel edges and clean cut.

The traction meter was prepared in the manner next. A load cell was installed for the type of meter of traction used and for the type of material tested. Be selected a load cell such that the values of interest were within the intervals recommended by the manufacturer among the values of the entire cell scale of load. The jaw separation speed was adjusted to 10 ± 0.4 inches / minute (25.4 ± 1 cm / minute). The sensibility Breaking was adjusted to a 65% drop from the peak. Also I know adjusted the strike compensation to 25 grams, and the points Default slopes were set to 70 and 157 grams. He threshold was adjusted to 2% of full-scale load. Further, the jaws were installed in the meter, and it was calibrated by the manufacturer for the traction meter / software used.

The measurement procedure began inserting the sample, centered and straight, into the jaws. TO then the jaws that extend through the width of the sample, while simultaneously eliminating excessive strike of the sample. Subsequently, the machine and the jaws separated. The rehearsal ended when it He broke the sample. After that, the results were recorded.

"Mullen burst" measures hardness of a material by swelling the material with a diaphragm until the It breaks itself. These tests can be carried out using conventional testing equipment and techniques. These essays are carried out using a resistance meter Mullen bursting, such as those manufactured by B. F. Perkins & Son Inc., whose address is GPO 366, Chicopee, MA 01021, or by Testing Machine Inc., whose address is 400 Bayview Avenue, Amityville, NY 11701. The test procedure included subjecting with tweezers a sample with a length and width of approximately 12.7 centimeters on a rubber diaphragm, swell the diaphragm by pressure, generated by entering liquid under pressure in a chamber at approximately 95 milliliters per minute, and record the pressure at which the sample was broken. The burst pressure was expressed in pascals.

The Mullen bursting procedure in wet also includes saturation of the sample with water purified and drying the excess water before holding the Show the team. Mullen's burst is expressed in pounds per square inch (psi). 1 pound per square inch = 6.895 Pa.

The "absorption rate" of water or of oil is the time required, in seconds, for a sample of tissue or paper absorbs a certain amount of test fluid. Water or oil absorbency for a paper sheet It is determined as follows. The absorption rate is the average of four absorbency readings (two on the face of the material exposed to the air and two on the face of the material exposed to dryer). Typically, white mineral oil (paraffin) is used for oil absorbency tests, and typically used deionized water for water absorbency tests. The Assays are carried out in a standard laboratory atmosphere, at 23 ± 1 ° C (73.4 ± 1.8 ° F) and at a relative humidity of 50 ± 2%.

To determine the absorption rate of water or oil, the selected test fluid is introduced into a small beaker and stainless steel. Used a support plate made of plexiglass or stainless steel, with approximate dimensions of 5 inches by 5 inches (12.7 cm per 12.7 cm) and with an opening two inches in diameter, for hold the sample on top of the glass of precipitates

Next, the tissue samples submitted to measurement they are conditioned in the manner described herein document. After conditioning, the samples are extended on top of the steel beaker stainless and cover with the support plate to hold them in their site. A pipette is filled with test fluid (water or oil) pressing the button halfway to fill the pipette, with 1 click. The tip of the pipette is held at one inch (2.54 cm) per above the sample and at right angles to it. TO then, the test fluid is transferred from the pipette to the shows, and the stopwatch is connected. Once the fluid has been completely absorbed by the sample, the chronometer.

If the stopwatch does not stop between the different samples, the total number of seconds must be divided by four and the number is recorded in seconds.

The "water capillarity effect" is refers to the speed at which the web absorbs water.  The test performed to measure the capillary effect determines the effects of the capillary action of a fluid on a tissue that it is suspended vertically and partially submerged in the fluid.

Capillarity effect is determined by holding with tweezers a part of the laminar element in a water bath, of such that the water bath is in contact with the sample. The Assays are carried out in a standard laboratory atmosphere, at 23 ± 2 ° C (73.4 ± 3.6 ° F) and at a relative humidity of 50 ± 5%. Tissue samples are cut in 1 by 8 portions ± 0.1 inch (25.4 by 203.2 ± 2.5 mm) in both material addresses, machine address (DM) and the machine transverse direction (DTM). The test samples are  obtained from areas of the sample that do not show creases, wrinkles No distortions of any kind.

Capillarity effect is based on the amount of water absorbed in the vertical direction given by the shows in a certain period of time. The container is filled with test fluid (deionized water) and the test sample is held by tweezers in the sample holder, which below it is positioned such that the lower edge of the strip extends approximately 1 inch (25.4 mm) inside the fluid. When he Free end of the sample is placed in the test fluid, it actuate the stopwatch and observe how the fluid migrates the sample upwards. At 15, 30, 45 and 60 seconds the height is recorded in centimeters from the lowest point of the edge of the fluid in migration.

TABLE 1

one

TABLE 2

2

TABLE 3

3

TABLE 4

4

TABLE 5

       \ vskip1.000000 \ baselineskip
    

5

       \ vskip1.000000 \ baselineskip
    

Examples 7-11

1 inch = 2.54 cm 1 pound / ton = 454 g / ton 1 PLI = 175 N / m

In these examples, a paper laminar element Produced according to cross-circulation drying technology air without crepe, with a basis weight of approximately 16 2,880 square feet / ream (27 g / m2), underwent calendering to reduce its uncompressed thickness. The element laminar was subjected to various pinch pressures per inch linear. Then the sheet elements were moistened produced to determine the level of recovery to its state not compressed.

The laminar elements were formed from a pulp load composed of 61% recycled fiber from Owensboro and 31% Mobile pine with approximately 20 pounds / ton of Kymene wet strength resin. The thickness of Uncompressed laminar element was approximately 0.008``. The compression thicknesses were determined as an average of thickness measurements taken in three different places of the element laminate. At a pressure of 63 PLI, the dry laminar element is compressed to about 0.0048 '', and at a pressure of 96 PLI, the dry laminar element was compressed to approximately 0.0042``. In all cases, after saturating the laminar element with water, the thickness recovered to about 0.0084 '' in 7 seconds and then stabilized at about 0.0070 '' after 2 minutes

Examples 12-16

1 inch = 2.54 cm 1 pound / ton = 454 g / ton 1 PLI = 175 N / m

In these examples, a paper laminar element Produced according to cross-circulation drying technology air without crepe, with a basis weight of approximately 16 2,880 square feet / ream (27 g / m2), underwent calendering described below to reduce its thickness not compressed. The laminar element was subjected to various pressures of pinched by linear inch. Then, the laminar elements produced to determine the level of recovery to its uncompressed state.

The laminar elements were formed from a pulp load composed of 61% recycled fiber from Owensboro and 31% Mobile pine with approximately 20 pounds / ton of Kymene wet strength resin. The element laminar presented a stretch of approximately 10% with a Immediate transfer of approximately 15%. The thickness of Uncompressed laminar element was approximately 0.0081 ''. TO a pressure of 13 PLI, the dry laminar element was compressed until about 0.0065 ''; at a pressure of 46 PLI, the element Dry laminar was compressed to about 0.0055 ''; and one 63 PLI pressure, the dry web was compressed until approximately 0.0048``. The 13 PLI laminar element returned up to approximately 0.0089``, the 46 PLI laminar element returned to approximately 0.0085 '', and the laminar element of 63 PLI returned to approximately 0.0083 '', after getting wet for 7 seconds The laminar elements of 13 PLI and 46 PLI are stabilized at about 0.0070 '' and 0.0071 '', respectively, after 2 minutes.

       \ newpage
    

Example 17

1 inch = 2.54 cm 1 pound / ton = 454 g / ton 1 PLI = 175 N / m

Another product consisting of a drying process by transverse air circulation without crepe (composed of 33% recycled fiber from Owensboro, a 13% recycled Fox River fiber and 52% Mobile pine with 20 pounds / ton of Kymene wet strength resin and one immediate transfer of approximately 25%) at Evaluations described above. The original thickness without Compressing this laminar element was approximately 0.022 ''. The web was compressed to 0.011 ''. After staying in wet for 7 seconds, the laminar element extended again until about 0.0144 ''.

Examples 18-21

1 inch = 2.54 cm 1 pound / ton = 454 g / ton 1 PLI = 175 N / m

In examples 18-21, compared a laminar element, formed according to the procedure of drying by transverse air circulation without creping, in state uncompressed (example 18); in a compressed state of 86% of original thickness (example 19); in a compressed state of 84% of original thickness (example 20); and in a compressed state of 71% of the original thickness (example 21).

The laminar elements of the examples 18-21 are formed from a paste load similar to that used in examples 1-3, and contain 55% recycled Owensboro fibers, 28% pine from Mobile, 7% of recycled Fox River fibers and 10% of waste. The laminar elements have a basis weight of approximately 16 pounds / ream (27 g / m2).

Examples 22-25

1 inch = 2.54 cm 1 pound / ton = 454 g / ton 1 PLI = 175 N / m

In examples 22-25, compared a laminar element, formed according to the procedure of strong wet creping, in an uncompressed state (example 22); in a compressed state of 79% of the original thickness (example 23); in a compressed state of 74% of the original thickness (example 24); and in a compressed state of 63% of the original thickness (example 25).

The laminar elements of the examples 22-25 are formed from a paste load which contains 45% Mobile pine, 15% hardwoods, a 30% waste and 10% chemothermal paste. The laminar elements have a basis weight between 18 and 19 pounds / ream (29-31 g / m2).

Examples 26-29

In examples 26-29, compared a laminar element, formed according to the procedure of drying by transverse air circulation without creping, in state uncompressed (example 26); in a compressed state of 85% of original thickness (example 27); in a compressed state of 68% of original thickness (example 28); and in a compressed state of 55% of the original thickness (example 29).

The laminar elements of the examples 26-29 are formed from a paste load containing 80% sulphite softwood pulp (pulp chemically processed with a mixture of sulfurous acid and ion bisulfite), 10% of chemothemomechanical soft wood pulp and 10% waste. The laminar elements have a basis weight between 17 and 19 pounds / ream (27,7-31 g / m2).

The following tables show various measurements made on the laminar elements formed in the Examples 18-29.

TABLE 6

6

TABLE 7

7

TABLE 8

8

TABLE 9

9

TABLE 10

10

       \ vskip1.000000 \ baselineskip
    

Examples 30-35

In examples 30-32, about laminar elements with base weights of approximately 16 pounds / ream (26 g / m2), produced from the load of paste used in examples 18-21, with 55% of recycled fibers of Owensboro, 28% of Mobile pine, 7% of Fox River recycled fibers and 10% waste were submitted at various stages of calendering or compression after calendering normal, in order to determine the amount of elastic return in the dry state Four samples of each item were compressed laminating with various calendering loads, and their thicknesses immediately after being compressed and after a 10 minutes, 50 minutes and 100 minutes period. Column of uncompressed thicknesses represents element thicknesses laminar before being subjected to these compression stages additional. In other words, the thickness column does not tablet shows values for laminar elements that only have undergone normal calendering, typical in a procedure of paper production, but that have not been subjected to forces of Additional calendering and compression. The table also shows an average for each particular laminar element.

For comparative purposes, they also submitted to similar tests laminar elements produced according to a drying process by transverse air circulation without creped and composed of 70% recycled fiber, 15% pine of Mobile and 15% of BCTMP. The results are shown in the table 12. The pressures applied to compress the laminar elements can be calculated by increasing by 3.35 psig and adding 12.5 to the value obtained.

The results show that the elements Laminators produced from BCTMP fiberless pastes show  some degree of recovery or elastic return along the time, such as the laminar elements produced from BCTMP fiber pastes.

TABLE 11

eleven

       \ vskip1.000000 \ baselineskip
    

TABLE 12

12

Examples 36-39

In the following examples, they were measured in been cured and not cured (i.e. after drying completely the sheets and after the sheets were semi-dry) the thicknesses of a laminar element with a basis weight of approximately 20 pounds / ream (33 g / m2) composed of 100% of recycled Ponderosa fibers with resistance agent in Kymene wet at 0.6% by weight fiber. Resistance agent  wet Kymene remains slightly uncured after only 3 minutes at 250ºF (121ºC). The sheets were subjected to certain compression levels, as indicated in tables 13 and 14. The results shown for example 36 in table 13 correspond to a laminar element heated in an oven for 3 minutes at 250ºF (121ºC). The results shown for the examples 37-39 in table 14 correspond to elements laminates heated for 20 minutes at 250 ° F (121 ° C).

As can be seen in the tables, the sheets that are not completely cured before compression exhibit a lower elastic return after wetting than fully cured sheets.

       \ vskip1.000000 \ baselineskip
    

TABLE 13

       \ vskip1.000000 \ baselineskip
    

13

       \ vskip1.000000 \ baselineskip
    

TABLE 14

       \ vskip1.000000 \ baselineskip
    

14

       \ vskip1.000000 \ baselineskip
    

Examples 40-47

In examples 40-47, they used the pasta load and the conditions used in the Examples 36-39. Examples 40-43 from table 15 show the results for a laminar element heated in an oven for 3 minutes at 250ºF (121ºC) and subjected subsequently to various compressions. Example 40 is an element  uncompressed laminar. Examples 44-47 of the Table 15 shows the results for a heated sheet element for 20 minutes at 250ºF (121ºC) and subsequently subjected to various compressions Example 44 is a non-laminar element compressed. As the results indicate, the ability to Water absorption for cured samples was not reduced substantially despite being highly compressed.

TABLE 15

fifteen

Although the present sheets have been tablet according to the present invention in order to reduce its dry thicknesses, the sheets exhibit a wet thickness that returns elastically when saturated with water. In addition, and despite be compressed, the water absorption capacities of Compressed sheets have not been substantially reduced by contrary to what conventional knowledge of the technique.

Although preferred embodiments have been described of the invention using terms, devices and methods specific, said description is purely illustrative. The Terms used are descriptive and not limiting. Should understand that those skilled in the art can carry out changes and variations without departing from the spirit or scope of the present invention, which is set forth in the appended claims. In addition, it should be understood that various aspects Embodiments can be exchanged totally or partially. In consequently, the scope of the appended claims should not limited to the description of the preferred versions contained in the same.

Claims (9)

1. Procedure for the formation of a laminar element based on absorbent and compressed paper that understands:

(i)

formation of a laminar element to paper base not compressed by a drying process by cross air circulation without creping, strong creping in wet or light dry crepe, which is incorporated into the element laminating a permanent or temporary wet strength agent; Y subsequently

(ii)

application of a force of compression to reduce the thickness of the web based paper, said compressed laminar element being capable of paper recover at least 70% of its original thickness at saturate with water;

characterized in that the compressive force reduces the thickness of the paper-based laminar element up to between 50% and 90% of its original thickness. 2. Method according to claim 1, in which, in step (i), the paper-based laminar element does not tablet is formed by a drying process by cross air circulation without creping. 3. Method according to claims 1 or 2, in which, in step (i), a laminar element is incorporated into permanent wet strength agent. 4. Procedure, according to one of the previous claims, wherein the agent is added wet resistance to pulp fibers, in an amount of, such as minimum, 0.1% by dry weight with respect to the dry weight of the pulp fibers 5. Procedure, according to one of the previous claims, wherein the laminar element paper-based tablet is able to recover at least the 80% of its original thickness when saturated with water. 6. Procedure, according to one of the previous claims, wherein the laminar element paper-based tablet has a water absorption capacity which is at least 70% of the water absorption capacity of the laminar element based on uncompressed paper. 7. Procedure, according to one of the previous claims, wherein the laminar element based on paper comprises fibers selected from pulp fibers of wood, mixtures of wood pulp fibers with synthetic fibers, or flax, milkweed, abaca, hemp or cotton fibers. 8. Procedure, according to one of the previous claims, wherein the compression force is apply by hot calendering or steam. 9. Procedure, according to one of the previous claims, wherein the basis weight of the element paper based laminate is between 25.8 and 30.8 g / m2 (between 15.5 and 18.5 pounds / ream), and the force of compression reduces the thickness of the paper-based laminar element up to a thickness between 0.168 and 0.254 mm (between 0.0066 and 0.01 inch)