KR20020047122A - A multi-ply tissue having a high caliper, low density, absorbent layer - Google Patents

Abstract

A tissue product having a high caliper, low density, absorbent inner layer is disclosed. The high caliper, low density, absorbent inner layer can be composed of passively or actively bonded hydrophilic fibers. Passively bonded hydrophilic fibers may include natural or synthetic fibers such as cotton and air blown pulp. Actively bonded hydrophilic fibers can include wet laid cellulose or nonwovens. Such inner layers may have calipers ranging from about 0.010 inches to about 0.030 inches and an apparent density of about 0.11 g / cm 3 or less.

Description

Multi-layered Tissue with High Caliper, Low Density, Absorbent Layer {A MULTI-PLY TISSUE HAVING A HIGH CALIPER, LOW DENSITY, ABSORBENT LAYER}

Cellulose fiber structures, such as paper webs, are known in the art. Such paper webs can be used for facial toilet paper, toilet paper, paper towels and napkins, each of which is widely used today. When such products perform their intended tasks and are widely employed, these fiber structures have appropriate properties in view of their absorbency, volume, strength and flexibility.

In addition, it is desirable to produce such paper webs that have enhanced the ability to prevent any fluid from passing through the web during use. For example, for facial toilet paper, it is preferable to sneeze, cough, and prevent passage of fluid on the body when blowing the nose. Such body fluids pose health risks due to the presence of bacteria, microorganisms or other pathogens. When bacteria carried by mucus, saliva or droplets of fluid on the body pass through facial toilet paper, these bacteria may remain in the hands of the user, providing a means of transferring microorganisms and, in some cases, diseases. Transmission of pathogens between humans is known to occur frequently by hand contact. Moreover, the only defense against many viral diseases, including the common cold, is to prevent their spread.

In order to prevent the fluid from passing through the tissue during use, the consumer performs various compensation actions. For example, many consumers fold in half or select several tissues at a time before using the tissue to improve the absorbency and strength as well as improve the insulation barrier to prevent the fluids from getting wet. Known. However, this practice may be suitable to prevent hand soaking during use, but greatly increases product consumption.

Attempts have been made to provide an insulating barrier layer on tissue products to prevent the spread of microorganisms, bacteria and other pathogens. For example, the one or more tissue layers can be treated with a material designed to immerse and contain droplets of fluid. However, such materials cannot form a complete insulating barrier in the passage of fluids, in particular droplets, which can easily "strikethrough" tissue, or easily absorbable liquids. Thus, the treated tissue cannot prevent contamination of the user's hands.

Another attempt to provide an effective insulating barrier layer involves the inclusion of one or more layers of flexible plastic material between layers of facial toilet paper. For example, US Pat. No. 5,196,244 to Beck discloses a very thin flexible material (eg, polyethylene) that is contained between layers of tissue and is embossed and held in place. However, plastic membranes can not only reduce the flexibility but also increase the noise of the tissue during use. In addition, to be safe (eg, to prevent accidental accidents), it is important to allow the tissue to penetrate air or steam to some extent.

U.S. Patent No. 4,885,202 to Lloyd et al. Discloses the use of meltblown fibers that are thermally bonded entirely between two outer tissue layers for wet strength. However, the required thermal bonding may not only add strength that adversely affects the drape and flexibility of the tissue product, but may also increase manufacturing costs.

In the technical field of disposable absorbent bandages, attempts have been made to distribute absorbent fluid and provide an absorbent fluff structure that acts as a dispensing agent or the like. Disposable absorbent bendages typically include baby diapers, adult incontinence products, and sanitary napkins, which are susceptible to repeated and heavy loading of fluid on the body. One such attempt in this technical field is described in US Pat. No. 4,141,772, issued Feb. 27, 1979, and US Pat. No. 4,217,078, issued Aug. 12, 1980, both of which are listed in Bel. Is hereby incorporated by reference herein. U.S. Patent Nos. 4,141,772 and 4,217,078 to Beer present an airlaid web comprising a five-ply stack with two airfelt layers, two tissue layers and a central reinforcement layer. Such a configuration is suitable for absorption bendage and fluid distribution, but cannot be implemented in the present invention. The configuration of the bulb shows two different layers of airfelt separated by reinforcement layers. Such a device can be implemented in a disposable absorbent bendage, but yields a product that is too thick and hard for use as a facial tissue or a toilet tissue. Moreover, the intention of facial toilet paper is to trap fluid on the body to prevent its spread, rather than distributing such body fluid throughout the product to accommodate a continuous load.

Therefore, it is desirable to supply tissue products that provide sufficient absorbency, flexibility, and hand protection without the need for compensatory actions to the consumer.

FIELD OF THE INVENTION The present invention relates to tissue products, and more particularly to tissue products having a high caliper, low density, absorbent inner layer.

1 is a cross-sectional view of a paper web with a liquid impermeable breathable insulating barrier layer in accordance with the present invention.

2 is a schematic side view of an apparatus for making a liquid impermeable breathable paper web having an insulating barrier layer in accordance with the present invention.

3 is a plan view of an alternative embodiment of the paper web of the present invention, partially cut away, showing adhesive bonding along at least two edges.

4 is a diagram of a typical output for flexural strength testing.

5 is a linear regression analysis diagram of the bending strength output of FIG. 4.

A tissue product having two outer cellulose layers and an inner layer is disclosed. This inner layer may be composed of passively or actively bonded hydrophilic fibers, which form a high caliper, low density absorbent layer. Passively bonded hydrophilic fibers may include natural or synthetic fibers such as cotton and air blown pulp. Actively bonded hydrophilic fibers may include wet laid cellulose or synthetic nonwovens. Such inner layers may have calipers ranging from about 0.010 inches to about 0.030 inches and an apparent density of about 0.11 g / cm 3 or less.

The tissue product may comprise a total caliper in the range of about 0.026 inches to about 0.044 inches, an absorbency in the range of about 15 g / g to about 30 g / g, a compressibility in the range of 20% to 99%, and a range of about 30% to 99% It may have a repulsion rate.

Justice:

As used herein, the following terms have the following meanings.

Basis weight is the weight per unit area (grams per square meter) of a sample reported in 1bs / 3000 ft ² .

The caliper is the macroscopic thickness of the sample measured as described below.

The apparent density is the basis weight of a sample divided into calipers by suitable unit processing included therein. The apparent density used herein has units of grams / cubic centimeters (g / cm 3).

The paper machine direction (MD) is the direction parallel to the flow of fibers through the product manufacturing equipment.

The paper machine width direction CD is a direction perpendicular to the paper machine direction on the same side of the tissue product.

Absorption is the ability of a substance to absorb a fluid and retain such fluid by various means including capillary, osmotic, solvent or chemical action.

Flexibility is a measure that does not break under a given load, and deforms itself without returning to its previous form.

The fiber is a slender object with a very long major axis compared to the two orthogonal axes and an aspect ratio of at least 4/1, preferably at least 10/1.

Hydrophilicity is a substance that has an affinity for sucking or absorbing water.

A "paper web" or "cellulose paper web" is a web of the present invention that includes one or more component layers composed of manually bonded hydrophilic fibers. For example, the web of the present invention includes hydrophilic fibers that are manually bonded between cellulose paper layers.

The term "ply" means individual web components arranged in a frontal relationship substantially adjacent to another layer, which forms the multi-layer web of the present invention. In addition, a single web component can be folded into itself, for example, to effectively form two “layers”. Thus, the cellulose layer folded on itself, together with the layer of passively bonded hydrophilic fibers inserted between the two folded portions, effectively forms the three-layer web of the present invention. In addition, the component layer folded on itself without any additional layers inserted between the folded portions effectively forms a two-layer web.

The term "liquid" is mainly a fluid on the body, such as water, mucus, saliva, blood and other body fluids, but may also include other liquids. "Liquid" is referred to as a liquid fluid as opposed to a gas or vapor fluid. Some body fluids, such as mucus, may have high viscosity, but are considered liquids for the present invention.

As used herein, “passivebonding”, referred to as fiber-to-fiber bond, means bonding, such as hydrogen molecular bonds or adhesive bonds in the absence of any external media, in which fibers are distributed by external forces. Try to slide against each other. By this definition, the tensile strength of a layer comprising passively bonded fibers is typically about 130 grams or less. Passive bonding is generally very light and represents the natural affinity of the materials in contact with each other. For example, passive bonding may be due to intrinsic electrostatic charge or cohesion. Passive bonding may also be referred to as bonding, which allows the materials to adhere cohesively to each other when the two layers of materials contact each other.

As used herein, “active bonding”, referred to as fiber-to-fiber bond, means bonding through an external medium, such as hydrogen bonding or adhesive bonding with an adhesive or latex. By this definition, the tensile strength of a layer comprising actively bonded fibers is typically at least about 130 grams. Active bonding, such as bonding between layers, can also include thermal or ultrasonic bonding, embossing, needling, and other mechanical engagement means as well as adhesive bonds.

In FIG. 1, the present invention comprises a tissue product 10, which is a facial tissue in a preferred embodiment. The tissue product 10 includes one or more high calipers, low density, absorbent inner layers 20, which are disposed between and adjacent two or more outer cellulose paper webs 30. The high caliper, low density, absorbent inner layer 20 can comprise passively or actively bonded hydrophilic fibers. Passively bonded hydrophilic fibers may include bicomponent synthetic fibers composed of polyethylene and polypropylene treated with surfactants for hydrophilicity, as well as natural fibers such as cotton and air blown pulp. Actively bonded fibers may include wet laid cellulose or synthetic nonwovens.

Although the described embodiment includes three layers, such an embodiment is not limiting. In fact, it may be desirable to form a multi-layer tissue product comprising various combinations of high caliper, low density, absorbent layers disposed between and adjacent cellulosic paper webs. Such various combinations are also contemplated within the scope of the present invention.

It is an advantage of the present invention to provide a tissue product having an absorbent capacity through the inner layer, which uses the product without the consumer wetting the hands and without compensating for actions such as folded tissue or multiple tissues. Do it. Thus, the tissue product of the present invention can be provided in a reduced size while providing the performance of a standard full size article. For example, the standard article size as facial toilet paper is about 72.6 inches ² . The size of the tissue product of the present invention may be a low limit of about 15 inches ² or a low limit of about 40 inches ^{2 to} a high limit of about 200 inches ² or a high limit of about 60 inches ² . In one embodiment, the tissue product is about 49.5 inches ² in size.

The advantages of the present invention are not limited to embodiments of facial toilet paper. For example, toilet paper, commonly referred to as toilet paper, may also benefit from the properties of high calipers, low density, absorbent inner layers. By having a flexible absorbent toilet paper, one may not have the unpleasant experience of wet fingers or hands during or after use. Moreover, the paper web of the present invention may be useful as paper towels, napkins, and the like.

The tissue product 10 may be prepared in one piece for use as facial toilet paper, napkins, paper towels or toilet paper, depending on the type of paper used in the cellulose paper web. Multiple paper webs 10 may also be provided in rolls with perforations to define individual web sections, where each section may be removed for use as is commonly used in toilet paper (eg, toilet paper). have. When prepared from toilet paper, roll dispensing is a good use, and paper found in commercially successful CHARMIN® brand tissue paper can be used as a cellulosic paper layer. However, in a preferred embodiment, the plurality of paper webs 10 may be cut, folded and optionally fitted with a pile of facial tissue suitable for dispensing from a container such as a box or a tub. In this embodiment, the paper found in commercially successful PUFFS® facial tissues can be used as a cellulose paper layer. Both CHARMIN tissue paper and PUFFS facial tissue are sold by The Procter & Gamble Co. of Cincinnati, Ohio.

Cellulose paper web

The cellulose paper web 30 may be a pleated paper web originally composed of cellulose papermaking fibers. Paper webs may have a basis weight range, the lower limit of which may be about 10 grams per square meter (gsm or g / m 2), about 13 g / m 2 per layer, or about 15 g / m 2 per layer. . The high limit of basis weight range may be about 100 g / m 2 per layer, about 40 g / m 2 per layer, or about 25 g / m 2 per layer. Cellulose paper web 30 may be a pleated, wrinkled or wet microcontracted tissue web suitable for use as facial toilet paper or premium facial toilet paper. Generally, paper webs 30 are used that are substantially identical in basis weight, thickness, composition, and other properties. However, certain advantages can be realized by using paper webs with different properties. For example, the component paper webs 30 differ in basis weight, thickness, composition, and other properties, providing a relatively smooth surface on one side of the paper web, and one side having a relatively rough surface.

The cellulose paper web 30 of the present invention may be manufactured by conventional processes known in the art to produce tissue paper useful for facial toilet paper, toilet paper, paper towels or napkins. However, the cellulose paper web 30 of the present invention can be produced by a hot air drying process using a patterned resin papermaking belt. The patterned resin papermaking belt may comprise two main components: a framework and a reinforcing structure. Such substructures may comprise cured polymer photosensitive resin.

One surface of the patterned resin papermaking belt contacts one surface of the cellulose paper web 30, for example, the first surface 31, carried thereon. During papermaking, this surface of the patterned resin papermaking belt can imprint a pattern on the first surface 31 of the cellulose paper web 30 corresponding to the pattern of the underlying structure.

A patterned resin papermaking belt suitable for carrying out a preferred embodiment of the present invention is described in US Pat. No. 4,514,345 to Johnson et al. April 30, 1985, to United States issued to Trocan on July 9, 1985. Patent 4,528,239, US Pat. No. 5,098,522, issued March 24, 1992, and November 9, 1993, US Patent No. 5,275,700 to Trokan, issued January 4, 1994, US Pat. U.S. Patent No. 5,431,786 to Rash et al. On July 12, U.S. Patent No. 5,496,624 to St. II on March 5, 1996, and U. S. Patent No. to Trocan et al. On March 19, 1996. 5,500,277, US Pat. No. 5,514,523 to Trocan et al. On May 7, 1996; US Pat. No. 5,554,467 to Trocan et al. On September 10, 1996, to Trocan et al. On October 22, 1996. U.S. Patent No. 5,566,724, issued April 29, 1997 to Trocan et al. U.S. Patent No. granted, and the 5.62479 million, and can be prepared according to U.S. Patent No. 5,628,876, issued May 1997, etc. to the eye May 13, Shores, which is incorporated by reference.

The cellulose paper web 30 of the present invention may have two main areas. The first region includes a stamping region imprinted on the internal structure of the patterned resin papermaking belt. The stamping area preferably comprises an essentially continuous network. The continuous network of the first region of the cellulose paper web 30 is formed on the original continuous internal structure of the patterned resin papermaking belt, and generally corresponds therein in terms of geometry and therein in position during papermaking. Are placed in close proximity.

The second region of cellulose paper web 30 may comprise a plurality of domes distributed throughout the imprinted network region. Such domes generally correspond to deflection conduits in patterned resin papermaking belts during papermaking in the geometric plane and position. Such a dome protrudes outwards in the region of the original continuous network of paper by conforming to the deflection conduit during the papermaking process. By adapting to the deflection conduit during the papermaking process, the fibers of the dome are deflected in the Z-direction between the paper facing surface of the internal structure and the paper facing surface of the reinforcing structure. Preferably, this dome is discontinuous.

Cellulosic paper web 30 according to the present invention is described in U.S. Patent No. 4,529,480 issued to Trocan on July 16, 1985, U.S. Patent No. 4,637,859 to Trocan on January 20, 1987, 1994 US Pat. No. 5,364,504 to Smerkowski et al. On Nov. 15, and US Pat. No. 5,529,664 to Trocan et al. On June 25, 1996. Cellulose paper webs may be prepared according to any cleaning agent added, e.g., in accordance with U.S. Patent No. 4,481,243 to Allen on November 6, 1984, and U.S. Patent No. 4,513,051 to Rabash on April 23,1985 lotion or emollient. The foregoing patents are incorporated herein by reference.

If desired, the cellulose paper web 30 may be dried and made by a hot air drying belt that does not have a patterned internal structure. Such cellulose paper webs 30 may have discontinuities, high density regions and inherently continuous low density networks. During or after drying, the cellulose paper web 30 can distinguish the vacuum state, increase its caliper, and desensify the selected area. Such papers and related belts are described in U.S. Patent No. 3,301,746 to Sanford et al. On January 31, 1967, and U.S. Patent No. 3,905,863, issued on September 16, 1975, to AIDS on August 10, 1976. U.S. Patent No. 3,974,025, issued U.S. Patent 4,191,609 to Trocan, dated March 4, 1980; U.S. Patent No. 4,239,065, issued December 16, 1980, to Trocan, November 22, 1994 US Pat. No. 5,366,785, issued to Sodai, and US Pat. No. 5,520,778, issued May 28, 1996, to Sodai. The foregoing patents are incorporated herein by reference.

The reinforcing structure can be a felt called press felt as used in conventional papermaking without hot air drying. U.S. Patent No. 5,556,509, issued to Trocan et al. On September 17, 1996; U.S. Patent No. 5,580,423, issued to Ampulsky et al. On December 3, 1996; US Pat. No. 5,629,052 to Trocan et al., May 13, 1997, US Pat. No. 5,637,194 to Ampulsky et al. June 10, 1997, and McFarland to October 7, 1997. As set forth in US Pat. No. 5,674,663, et al., The internal structure of a patterned resin papermaking belt can be applied to felt reinforcing structures, which are incorporated herein by reference.

The cellulosic paper web 30 of the present invention may optionally be foreshortened, as is known in the art. Miniaturization can be achieved by creping the cellulose paper web 30 from a hard surface, preferably a cylindrical surface. Yankee drying drums are commonly used for this purpose. Creping is accomplished with a doctor blade, as is known in the art. Creping may be accomplished in accordance with US Pat. No. 4,919,756, issued to Sodai on April 24, 1992, which is incorporated herein by reference. Alternatively or additionally, miniaturization can be achieved through wet microcontraction, as set forth in US Pat. No. 4,440,597 to Wells et al. On April 3, 1984, wherein the patent is herein Included by reference.

High Caliper, Low Density, Absorption Inner Layer

Apart from simply preventing the diffusion of airborne fluid droplets, the paper web of the present invention is also useful for sneezing and drying the user's hands when blowing the nose. For example, wiping and washing after sneezing or blowing your nose can often wet your fingers or hands. Thus, users often fold a single tissue in half or use several tissues at once to avoid getting wet. The high caliper, low density, absorbent inner layer of the present invention can prevent the user from experiencing undesirable wetness without folding or using multiple tissues at once. The high caliper, low density, absorbent inner layer 20 may comprise passively or actively bonded hydrophilic fibers.

Passively bonded hydrophilic fibers may be stored as roll stock for use in the papermaking process by including cotton wrappers formed in the nonwoven web. Optionally, the passively bonded hydrophilic fibers may comprise natural fibers such as cotton fibers and air blown pulp, or synthetic fibers such as bicomponent fibers composed of polyethylene and polypropylene treated with a surfactant to provide hydrophilicity. have. Such natural or synthetic fibers may be introduced between the outer cellulose layers through an air forming process. In this air forming process, the first paper web is provided on an air permeable forming wire. These forming wires and webs pass through a vacuum section, where dry cotton or pulp fibers are fed to a moving air system to vacuum into the first paper web. The forming wire, the first paper web and the layer of dry fiber exit the vacuum section and are covered by a second paper web.

Actively bonded hydrophilic fibers can include wet laid cellulosic webs and nonwovens. Wet laid cellulose webs that provide a high caliper, low density, absorbent inner layer can be made by the hot air drying process described above using a patterned resin papermaking belt. Wet laid webs that provide a high caliper, low density, absorbent inner layer can include single or multiple lamina cellulose structures, each laminae, issued December 1, 1998, to United States, et al. As set forth in patent 5,843,279, it has three or more identifiable regions that can be distinguished from one another by their intensive nature. Intensity properties that can be used to identify and distinguish different regions of the fibrous structure are basis weight, thickness, density, and projected average pore size.

If the high caliper, low density, absorbent inner layer 20 comprises cotton wrappers, cellulose webs or nonwovens, the inner layer 20 is brought into the tissue product 10 by the combination device 200 as shown in FIG. 2. Can be processed. In the configuration shown, cellulose web 30 can be pulled into roll 230 and high caliper, low density, absorbent inner layer 20 can be pulled into roll 240. The inner layer 20 and the cellulose web layer 30 can be combined into the web 10 of the present invention by pulling through the combination roller 250, which combines the component layers adjacently The component layer can be compressed to achieve passive bonding therebetween.

Multilayer tissue products

The outer cellulose layer of the multilayer tissue product of the present invention may be formed by manually or actively bonding the outer cellulose layer to the opposite side of the inner high caliper low density inner layer. Passive bonding provides a relatively small bond strength between the layers, allowing the layers to hold together for normal use. When used as folded and stacked tissue and core wound tissues, the tissue product 10 of the present invention is sufficiently bonded between the layers to prevent accidental debonding of the layers. Not theoretically bound, passive bonding of the layer can be caused by the electrostatic charge provided to the material and can vary to some extent due to other factors, such as the relative moisture levels of the layer components. Light active bonding may also occur due to the mechanical bonding of the exposed fibers of the inner layer 20 to the contact fibers of the cellulose web 30. Mechanical bonding is similar to "hook and loop" fasteners, where bonding is facilitated by engaging the number of components and the female members.

The layer of tissue product 10 of the present invention may be manually bonded by the method described above with reference to the apparatus shown in FIG. 2. However, if desired, an amount of adhesive or other active bonding means may be added to provide additional adhesive to the portion of the component layer. For example, needling, embossing, other thermal or mechanical bonding means can be used to actively bond the paper web 30 near some or all edges of the paper web 30, thereby providing a component layer. It is possible to increase the undesired interlayer adhesion strength of.

Bonding may also be by ultrasonic bonding or similar bonding, as described in US Pat. No. 4,919,738 to Ball et al. April 24, 1990, or other bonding methods known in the art. For example, if the edge of the inner layer is in the same range as the edge of the outer layer, adhesive bonding may not provide active bonding and surface energy characteristics of the inner layer depending on the adhesive use. In this case, mechanical bonding may be more desirable, for example, by mechanical bonding at the mechanical bonding station after forming the multilayer web. Figure 2 shows a mechanical bonding station, which may be an embossing roller, ultrasonic bonding means, need ring means or other non-adhesive bonding method.

As shown in FIG. 3, the tissue product 10 of the present invention may be composed of two outer cellulose layers 30, and a high caliper, low density, absorbent inner layer 20, such inner layer 20. Silver, as described above, may comprise cotton wrappers, cotton fibers, or air blown pulp, and has a width dimension W1 that is less than the width dimension W2 of the outer cellulose layer. By placing the inner layer with small width dimension W1 between the two outer layers, the two outer cellulose layers can be bonded to the edges in the bonding area 25 as by an adhesive strip. Bonding or bonding may be accomplished by a continuous strip of adhesive, a discontinuous strip such as a point of adhesion, or as set forth in US Pat. No. 5,143,776 to Given, which is incorporated herein by reference. In one embodiment, as shown in FIG. 2, the adhesive may be used along the opposite longitudinal edge in the mechanical direction by a print applicator 260. Print applicator 260 may be a rolling applicator, such as a gravure roller, or may be a spray applicator, or other adhesive applicator known in the art.

Optionally, the inner high caliper, low density absorbing layer has a smaller surface area than the two outer layers, so that the two outer layers can be joined along an edge forming a perimeter surrounding the inner layer. At the present time, the perimeter can occupy up to 30% of the total surface area of the tissue product, preferably the perimeter can occupy up to 20% of the entire surface area, and more preferably the perimeter can cover the entire surface. It can occupy 10% or less of the area.

Although FIG. 3 shows a high caliper, low density, absorbent inner layer with a smaller width dimension than the outer layer, other dimensions are possible, and the only limitation is that the outer layer can be joined to any portion, such as one or more edges. . For economical processing, the preferred configuration is as described, i.e., to make the width dimension smaller (corresponding to the paper machine width dimension). In this way, active bonding (such as adhesion, mechanical, autogenous, etc.) can be done continuously in length dimensions (corresponding to the paper machine direction) during subsequent web processing.

Material properties

Tissue products such as disposable towels, toilet papers, facial papers, napkins and wet wipes exhibit various physical properties, including the basis weight and apparent density defined above. Basis weight and apparent density relate to the bulkiness of the tissue product, which provides consumer confidence that hands dry after use without performing a compensating action. For the present invention, the entire tissue product may have a basis weight of about 20 lbs / 3000 ft ² (33 g / m 2) to about 80 lbs / 3000 ft ² (130 g / m 2), but with a high caliper, low density, absorbent interior The basis weight of the layer can be from about 8 lbs / 3000 ft ² (13 g / m 2) to about 16 lbs / 3000 ft ² (26 g / m 2). More preferably, the tissue product may have a basis weight of about 30 lbs / 3000 ft ² (49 g / m 2), while the high caliper, low density, absorbent inner layer is about 12 lbs / 3000 ft ² (20 g / m 2) It can have a basis weight of. Moreover, the tissue product of the present invention may have an apparent density range with a low threshold of about 0.04 g / cm 3 or about 0.06 g / cm 3. In addition, the apparent density range may have a high limit of about 0.12 g / cm 3 or about 0.08 g / cm 3. In one embodiment, the tissue product of the present invention has an apparent density of about 0.07 g / cm 3. Moreover, the high caliper, low density, absorbent inner layer of the tissue product may have an apparent density of about 0.11 g / cm 3 or less or about 0.06 g / cm 3 or less.

For the present invention, the tissue product may have a caliper of about 0.026 inch to about 0.044 inch, mainly due to the high caliper, low density, absorbent inner layer, which can be 50% or 66% of the caliper of the whole product. The caliper of the high caliper, low density, absorbent inner layer can have a low threshold of about 0.010 inches or about 0.014 inches. In addition, the caliper range of the inner layer can have a high threshold of about 0.030 inches or a high threshold of about 0.24 inches.

Flexibility is described as a physiologically perceived attribute, usually measured by expert or non-expert panel assessment. The perceived flexibility is divided into two components, volume flexibility and surface flexibility. Surface flexibility is related to surface texture and smoothness, but volume flexibility is related not only to flexibility but also to mechanical properties such as compressibility and elasticity. Compression rate is a measure of the ability to reduce the volume of a product by applying pressure. Elasticity is the ability to restore and deform a product's size. Softness is related to sheet stiffness.

The tissue product of the present invention may have a compressibility measured in the range of a low threshold of about 20% or a low threshold of about 40% as described below. The high limit of the compressibility range may be about 99%, about 70% or about 43%.

The elasticity of the tissue product of the present invention is measured by its ability to recover in a compressed state. The method used in measuring the resilience of the tissue product is measured by percent rebound as described below. For the present invention, the tissue product may have a percent rebound range with a low threshold of about 30% or a low threshold of about 65%. The high threshold of the percent rebound range may be about 99% or about 85%.

High flexibility requires flexibility. Softness is a function of the stiffness measured by the flexural strength of the material. For the present invention, the stiffness of the tissue product is measured on CD and MD. The method used to measure the stiffness is described below. For the present invention, the tissue product has a CD stiffness ranging from about 0.018 gf * cm 2 / cm to about 0.373 gf * cm 2 / cm and MD ranging from about 0.008 gf * cm 2 / cm to about 0.235 gf * cm 2 / cm. It can have a stiffness.

Products such as disposable towels, toilet paper, facial toilet paper, napkins and wet wipe papers require a certain level of absorbency. Here, the absorbency means the absorption capacity measured by the amount of distilled water absorbed and retained by the tissue. The high caliper, low density, hydrophilic fibers of the absorbent inner layer of the present invention enhance the capillary action and corresponding absorption of tissue products. The method used to determine the absorbency of the tissue product is described below. For the present invention, the tissue product may have a low limit of absorbency range of about 15 g _Water / g _{Dry Structure} or about 19 g _Water / g _{Dry Structure} . The high limit of the absorbance range may be about 30 g _Water / g _{Dry Structure} or about 25 g _Water / g _{Dry Structure} .

Method

(a) Sample conditioning and preparation

Prior to testing, the samples were subjected to a relative humidity of 48% to 50% and 22 ° C to 24 ° C until a moisture content of about 5% to about 16% was achieved with weight as measured by TGA (thermal gravimetric analysis). It is pretreated within the temperature range of. For thermal gravimetric analysis, Hi-res. TGA2950 thermal gravimetric analyzer from TA instruments is used. Approximately 20 mg of sample is weighted to the TGA pan. According to the manufacturer's instructions, the sample and pan are inserted into the unit and the temperature is increased at a rate of 10 ° C / min to 250 ° C. The% moisture of the sample is determined using the initial weight and weight reduction as follows:

Where all weights are in milligrams.

(b) basis weight

One stack of eight layers is formed from pretreated samples. The stack of eight layers is cut into 4 inches by 4 square inches. Acme Steel Rule Die Corp. A rule die from (5 Stevens St. Waterbury Conn., 06714) is used to achieve this cleavage.

In order to actually measure the weight of the sample, a top loading balance with a minimum resolution of 0.01 is used. The stack of eight layers is placed in a pan of top loading balance. This balance is protected from ventilation and other disturbances using a draft shield. The weight is recorded when the reading on the balance becomes constant. Weight is measured in grams.

The weight reading is divided by the number of layers tested. The weight reading is also divided into the area of the sample, which is usually 16 square inches, which is approximately equal to 0.0103 square meters.

The unit of measure for basis weight as used herein is grams per square meter. This is calculated using the 0.0103 square meter area described above.

(c) caliper

The pretreated sample is cut to a size larger than the size of the foot used to measure the caliper. The foot used is a circle with an area of 3.14 square inches.

This sample is placed on a horizontal plane and confined between the plane and a load foot having a horizontal loading surface, the load foot loading surface having a circular surface area of about 3.14 square inches, and about 15 g / cm 2 (0.21). psi) is applied to the sample. The caliper is the resulting gap between the plane and the load foot loading surface. Such measurements can be accomplished by the VIR Electronic Thickness Tester Model II available from Philadelphia Twin-Albert, Pennsylvania. Caliper measurements are repeated and recorded at least five times. Results are reported in millimeters.

The sum of recorded readings from the caliper test is divided by the number of recorded readings. Results are reported in millimeters (mm).

(d) compression rate

The compressibility is determined by applying a stack of eight samples of tissue product to a given pressure and observing the linear spacing in which the movable face is displaced on parallel surfaces by the stack of samples. For a stack of eight samples of the tissue product of the present invention, the displaced linear spacing is at least about 0.080 inches. Compression ratio is measured by percent compression by the following equation.

Percent compression =

here,

T1 = original thickness of 8 samples of tissue product (@ 0.05 psi)

T2 = Compressed thickness of 8 samples of tissue product (@ 1 psi)

And

T1-T2 ≥0.080 inch

(e) elasticity

For the present invention, the elasticity of the tissue product is measured by its ability to rebound and recover from the compressed state. Average compression and rebound are determined by observing the linear spacing in which the movable face is displaced on the parallel surface by the tissue product under the specified pressure, and the linear spacing restored after the designated time interval in which the pressure is removed. Percent recovery is determined by the equation

Percent Rebound = T ₃ / T ₁ × 100

here,

T1 = original thickness of 8 samples of tissue product (@ 0.05 psi)

T3 = restored thickness of 8 samples of tissue product (@ 0.05 psi)

Cyclic tests to measure percent compression and percent rebound:

The sample is cut to 4 "x 4". A stack of 8 samples is used for each test. The sample is then placed on a plane. The initial height of the stack is measured using a digital linear gauge. The foot on the digital gauge has a diameter of 1.56 "and applies 40 grams causing a pressure of 0.05 psi on the stack. On a pneumatic platform, 863 grams of weight load are placed, which is sampled. Calculate a pressure of 1 psi when placed in. The height of the sample is measured without the rod, the rod is applied for 1 second and then removed The height of the stack is measured through the test, depending on the measured stack height,% compression And% rebound can be calculated using the above equation.

(f) stiffness

Equipment for measuring stiffness:

The stiffness of the tissue product is measured using the pure bending test to determine the flexural strength using the KES-FB2 pure bending tester. Pure bending tester is the instrument of KES-FB series of evaluation system of Kawasea. These units are designed to measure the basic mechanical properties of fibers, nonwovens, paper, and other membrane-like materials, and are available from Kyoto Kato Tekosa, Japan.

Flexural properties are important for evaluating reinforcing structures and are one of the useful methods of determining strength. In the past, cantilever methods have been used to measure properties. KES-FB2 tester is the instrument used for pure bending test. Unlike the fragment support scheme, these mechanisms have a particular form. The entire tissue product sample is precisely bent into an arc of constant radius, and the angle of the curve changes continuously.

How to measure stiffness:

The tissue product sample is cut to almost 15.2 × 20.3 cm in the paper machine direction and paper machine width direction, respectively. Each sample is placed in a jaw of KES-FB2 so that the sample is bent first, the first surface is taut, and the second surface is compressed. In the direction of KES-FB2, the first surface faces to the right and the second surface faces to the left. The distance between the front and rear stop jaws is 1 cm. This sample is fixed to the instrument in the following manner.

First, the front moving chuck and the rear stop chuck are opened to receive a sample. The sample is inserted midway between the top and bottom of the bath. The back stop chuck is then closed by evenly tightening the upper and lower thumbscrews until the sample is convenient but not over tight. The jaws on the front stop chuck are then closed in a similar fashion. The sample is adjusted for the chuck's squares, then the front jaw is tightened to keep the sample safe. The distance d between the front chuck and the back chuck is 1 cm.

The output of the instrument is the load cell voltage Vy and the curve voltage Vx. The load cell voltage is converted into a bending moment normalized for the sample width in the following manner.

Moment (M, gf * ㎠ / cm) = (Vy * Sy * d) / W

Where Vy is the load cell voltage,

Sy is the instrument sensitivity of gf * cm / V,

d is the distance between chucks,

W is the sample width in centimeters.

The switch sensitivity of the mechanism is 5 × 1. Using this setting, the instrument is calibrated using two 50 gram weights. Each weight is hung on a thread. This thread is wound on a bar on the lower end of the rear stop chuck and hooked to a pin extending from the front and back of the center of the shaft. One heavy thread is wound on the front and hooked to the back pin. The other heavy thread is wound on the back of the shaft and hooked to the front pin. Two pulleys are fixed to the instrument on the right and left sides. The top of the pulley is flush with the center pin. Thereafter, both weights are hung on the pulley at the same time (one on the left and the other on the right). The full scale voltage is set to 10V. The radius of the central shaft is 0.5 cm. Thus, the resulting maximum sensitivity (Sy) for the moment axis is 100 gf * 0.5 cm / 10 V (5 gf * cm / V).

The output to the curved axis is corrected by starting the measurement motor and manually stopping the moving chuck when the indicator dial reaches 1.0 cm −1. The output voltage (Vx) is adjusted to 0.5 volts. The resulting sensitivity (Sx) for the curve axis is 2 / (volts * cm). The curvature K is obtained in the following manner.

Curvature (K, cm-1) = Sx * Vx

Where Sx is the sensitivity of the curve axis,

Vx is the output voltage.

In order to determine the flexural strength, the mobile chuck at a rate of 0.5 cm-1 / sec 0cm ^-1 - it is circulated to the curvature of the 0 cm ^-1 - -1cm ^-1 cm ^-1 in the curvature of +1. Each sample is cycled continuously until four full cycles are obtained. The output voltage of the instrument is recorded in digital format using a personal computer. Typical output for flexural strength is shown in FIG. 4. At the time of testing there is no flatness on the sample. As the test begins, the load cell begins to experience the load when the sample is bent. Initial rotation takes place clockwise when viewed from the top down on the instrument.

In forward bending, the first surface of the fiber appears flat and the second surface is compressed. The rod continues to increase until the bending curvature reaches approximately +1 cm ⁻¹ (which is the front deflection FB, as shown in FIG. 4). At approximately +1 cm ^-1 , the direction of rotation is reversed. Upon return, the load cell read is reduced. This is the forward bending return (FR) method. As the rotary chuck passes zero, the curve starts in the opposite direction. That is, the sheet side is now compressed and the non-sheet side extends. The back deflection BB extends approximately -1 cm ^-1 , in which the direction of rotation is reversed, so that a back deflection return BR is obtained.

In Figure 5, the data is analyzed in the following manner. A linear regression line is obtained between approximately 0.2 and 0.7 cm ⁻¹ for forward deflection (FR) and forward deflection return (FR). The linear regression line is obtained between approximately 0.2 and 0.7 cm ⁻¹ for the posterior deflection (BB) and the posterior deflection return (BR). The slope of this line is the flexural strength (B). It has units of gf * cm ² / cm.

This is obtained during each of four cycles for each of the four segments. The slope of each line is reported as flexural strength (B). It has units of gf * cm ² / cm. The flexural strength of the forward deflection is known as BFB. The individual segment values of 4 cycles are averaged and reported as mean BFB, BFR, BBF, BBR. Two separate samples of MD and CD are run. The values of the two samples are averaged together. MD and CD values are reported separately. These values are reported in Table 2.

Table 2: Flexural Strength (Stiffness) Values

Flexural strength (gf * ㎠ / cm) Sample MD / CD AVG BFB AVG BFR AVG BBF AVG BBR AVG AVG Puffs ss MD -.003 .014 .008 .001 .008 Puffs basic CD .024 .028 .017 .007 .018 Puffs AES MD .049 .055 .025 .040 .042 Puffs AES CD .033 .038 .017 .025 .028 CODE 10 MD .092 .104 .074 .084 .088 CODE 10 CD .143 .134 .107 .121 .126 CODE 13 MD .239 .275 .227 .200 .235 CODE 13 CD .380 .413 .376 .321 .373 Airflow Pulp MD .067 .067 .055 .052 .060 Airflow Pulp CD .072 .071 .061 .047 .063 if MD .090 .099 .079 .068 .084 if CD .123 .118 .117 .093 .169

Puffs SS-Products currently available as Puffs Soft and Strong

Puffs AES-Products currently in circulation as Puffs Advanced Extra Strength

Code 10-2 cellulose outer layer formed from @ 400 psi calendered cellulose inner layer using hot air drying process

Code 13-4 Cellulose layer formed using hot air drying process

Airflow Pulp-Two cellulose outer layer formed of airflow dry pulp fibers as an intermediate layer using conventional processes

Cotton-2 cellulose outer layer formed of cotton wrapper as an intermediate layer using conventional processes

(g) absorbance

The absorbency of the tissue product is determined in particular using a system designed to measure the water absorption (ie both rate and volume) of the tissue product. Wicking of moisture into a sample of tissue product is measured as moisture gain (weight) over time.

This test measures the absorption and capacity of paper products, in particular paper towels, facial tissues, toilet papers, and napkin products. 3 inches in diameter of the circle is cut at the center of the test product. The test sample is then placed in an open weave net away from the top loading balance. The center of the test sample then comes into contact with a water source such that moisture is wicked into the sample. The wicking of the water continues until a preset time. The moisture absorbed by the sample (weight gain) is measured over time. This test provides the absorbance of the sample (g / sec) and the absorbent capacity of the sample (grams of fluid / gram of sample).

Data points (ie weight and time) are collected and analyzed by a computer program. For each data point, the following calculation is made (all units are in grams).

Absorption Capacity = (Sample Wet Weight-Sample Dry Weight) / Sample Dry Weight

The computer program repeats the calculation for each data point. Each data point is averaged together and reported in g _Water / g _{Dry Structure} (grams of water / gram of sample dry weight).

Although specific embodiments of the invention have been described, those skilled in the art may make various changes and modifications within the spirit and scope of the invention. Such changes and modifications are possible within the scope of the appended claims.

Claims (10)

As a tissue product, And a second outer cellulose layer and an inner layer interpolated between the two outer layers, the inner layer consisting of passively bonded hydrophilic fibers. As a tissue product, 2. An article of tissue, comprising an outer layer of cellulose and an inner layer interpolated between the two outer layers, the inner layer consisting of cotton. As a tissue product, The tissue product includes an outer layer of two outer cellulose layers and an actively boarded hydrophilic fiber, the inner layer having an apparent density of about 0.11 g / cm 3 or less and a caliper in the range of about 0.017 inches to about 0.028 inches. , Tissue products. A tissue product having a compressibility in the range of 20% to about 99%, The tissue product includes an outer layer of two outer cellulose layers and an actively boarded hydrophilic fiber, the inner layer having an apparent density of about 0.11 g / cm 3 or less and a caliper in the range of about 0.017 inches to about 0.028 inches. , Tissue products. The method of claim 1, And wherein the compressibility ranges from about 20% to about 99%. The method of claim 1, A tissue product, characterized in that it has a percent rebound in the range of about 30% to about 99%. The method of claim 1, A tissue product comprising a surface area of about 70 square inches or less. The method of claim 1, And a full caliper, wherein the full caliper has a range from about 0.026 inches to about 0.044 inches. The method of claim 3, wherein And wherein the compressibility ranges from about 20% to about 99%. The method of claim 4, wherein And wherein the percent rebounds range from about 30% to about 99%.