1	70	Low	Feeding/Conveying	Feeding andMixing
2	70	Low	Conveying	Mixing and Conveying
3	70	Low	Conveying	Mixing and Conveying
4	130	Low	Pressure/Decreased	Conveying and Heating
			Conveying
5	300	Medium	Pressure Generating	Cooking at Pressure and
				Temperature
6	250	High	Reversing	Cooking at Pressure and
				Temperature
7	210	Low	Conveying	Cooling and Conveying
				(with venting)
8	210	Low	Pressure Generating	Conveying

After the third hydroxyl polymer composition exits the extruder, part of the polymer composition can be dumped and another part (100 g) can be fed into a Zenith®, type PEP II (Sanford N.C.) and pumped into a SMX style static mixer (Koch-Glitsch, Woodridge, Ill.). The static mixer is used to combine additional additives such as crosslinking agents, crosslinking facilitators, external plasticizers, such as water, with the third hydroxyl polymer composition. The additives are pumped into the static mixer via PREP 100 HPLC pumps (Chrom Tech, Apple Valley Minn.). These pumps provide high pressure, low volume addition capability. The third hydroxyl polymer composition of the present invention exhibits a Capillary Number of at least 1 and thus, is ready to be polymer processed into a hydroxyl polymer fiber.
b. Polymer Processing the Polymer Composition into a Hydroxyl Polymer Fiber

The hydroxyl polymer composition is then polymer processed into a hydroxyl polymer fiber. Nonlimiting examples of polymer processing operations include extrusion, molding and/or fiber spinning. Extrusion and molding (either casting or blown), typically produce films, sheets and various profile extrusions. Molding may include injection molding, blown molding and/or compression molding. Fiber spinning may include spun bonding, melt blowing, continuous fiber producing and/or tow fiber producing. Fiber spinning may be dry spinning or wet spinning. Monocomponent fibers comprising the hydroxyl polymer composition are formed by the fiber spinning.

c. Forming Hydroxyl Polymer Fiber Fibrous Structure

Hydroxyl polymer fibers produced as a result of polymer processing of the polymer composition in accordance with the present invention may be combined into a fibrous structure by collecting a plurality of the fibers onto a belt or fabric.

A plurality of solid additives may be combined with the hydroxyl polymer fibers as the fibers are being deposited onto a collection device, such as a belt or fabric.

In one example, a first gas stream may comprise a plurality of hydroxyl polymer fibers and a second gas stream may comprise a plurality of solid additives. The two gas streams may be combined prior to and/or concurrently with depositing the hydroxyl polymer fibers and solid additives onto a collection device such that the solid additives are entrained within and/or on the resulting fibrous structure. An example of equipment suitable for use in this type of process are described in US Patent Application 2003/0114067.

A fibrous structure of the present invention may then be post-processed by subjecting the web to a post-processing operation. Nonlimiting examples of post processing operations include contacting the fibrous structure with a plurality of solid additives, curing, embossing, thermal bonding, humidifying, perfing, calendering, printing, differential densifying, tuft deformation generation, and other known post-processing operations.

d. Contacting Surfaces of a Fibrous Structure with Solid Additives

Solid additives may be applied to a fibrous structure by any suitable means known in the art. When solid additives are applied to a fibrous structure, a surface of the fibrous structure comprising the solid additives is formed. A nonlimiting example by which solid additives may be applied to the fibrous structure is by using a Dan Web former, an example of which is described in U.S. Pat. No. 5,885,516, commercially available from Dan-Web of Risskov, Denmark.

Hydroxyl Polymer Fiber Fibrous Structure

As shown inFIG. 2, a hydroxyl polymerfiber fibrous structure20 comprises a hydroxyl polymer fiber22 (a plurality ofhydroxyl polymer fibers22 may form a base substrate upon which solid additives may be deposited) and asolid additive24, which may be a particle and/or a naturally occurring fiber.

The hydroxyl polymerfiber fibrous structure20 may comprise afirst surface26 and asecond surface28 opposite from thefirst surface26 as shown inFIG. 3. Thesolid additive24 may be present on a surface of the fibrous structure, such as thefirst surface26. Thesolid additive24 may cover less than the entire surface area of the surface of the fibrous structure. Thesolid additive24 may be present on the surface of the fibrous structure in a random pattern. Thesolid additive24 may be present on the surface of the fibrous structure in a non-random repeating pattern.

For explanation and/or clarity purposes, thesolid additives24 are shown in a dispersed nature, however, the concentration of thesolid additives24 on thefirst surface26 of the hydroxyl polymerfiber fibrous structure20 and/or thesecond surface28 of the hydroxyl polymerfiber fibrous structure20 may be such that the entire surface area or almost the entire surface area of thefirst surface26 and/or thesecond surface28 may be in contact with thesolid additives24.

As shown inFIGS. 4 and 5, in one example of the present invention, a multi-layered hydroxyl polymerfiber fibrous structure30 comprises afirst layer32 comprising a plurality of hydroxyl polymer fibers, asecond layer34 comprising a plurality of solid additives, and athird layer36 comprising a plurality of hydroxyl polymer fibers.

In one example, thefibrous structure30 may comprise at least one layer comprising a majority of non-naturally occurringhydroxyl polymer fibers22 and at least one layer comprising a majority ofsolid additives24.

In another example, thesolid additives24 may be uniformly or substantially uniformly distributed throughout the fibrous structure.

In yet another example, thesolid additives24 may be non-uniformly distributed throughout the fibrous structure.

FIG. 6 illustrates still another example of a hydroxyl polymer fiber fibrous structure of the present invention. The hydroxyl polymerfiber fibrous structure20 comprises ahydroxyl polymer fiber22 and a plurality ofsolid additives24. As shown inFIG. 6, the plurality ofsolid additives24 are arranged in a non-random, repeating pattern on a surface of the hydroxyl polymerfiber fibrous structure20. Depositing the solid additives in a non-random, repeating pattern can be achieved by any suitable means known in the art. For example, a patterned mask may be placed on the hydroxyl polymer fiber fibrous structure such that only the open areas of the mask allow the solid additives to contact a surface of the hydroxyl polymer fiber fibrous structure.

FIG. 7 illustrates still yet another example of a hydroxyl polymer fiber fibrous structure of the present invention. The hydroxyl polymerfiber fibrous structure20 comprises ahydroxyl polymer fiber22 and a plurality ofsolid additives24. As shown inFIG. 7, the plurality ofsolid additives24 are arranged in a random pattern on a surface of the hydroxyl polymerfiber fibrous structure20.

In one example, the hydroxyl polymer fiber fibrous structure of the present invention may comprise greater than 40% and/or greater than 45% and/or greater than 50% by bone dry weight of the hydroxyl polymer fibers.

In another example, the hydroxyl polymer fiber fibrous structure of the present invention may comprise less than 60% and/or less than 50% and/or less than 30% and/or less than 15% and/or less than 5% and/or less than 2% by bone dry weight of the solid additives.

Test Methods

Unless otherwise indicated, all tests described herein including those described under the Definitions section and the following test methods are conducted on samples that have been conditioned in a conditioned room at a temperature of 73° F.±4° F. (about 23° C.±2.2° C.) and a relative humidity of 50%±10% for 24 hours prior to the test. Samples conditioned as described herein are considered dry samples (such as “dry fibrous structures”) for purposes of this invention. Further, all tests are conducted in such conditioned room. Tested samples and felts should be subjected to 73° F.±4° F. (about 23° C.±2.2° C.) and a relative humidity of 50%±10% for 24 hours prior to testing.

A. Pore Volume Distribution Test Method

Pore Volume Distribution measurements are made on a TRI/Autoporosimeter (TRI/Princeton Inc. of Princeton, N.J.). The TRI/Autoporosimeter is an automated computer-controlled instrument for measuring pore volume distributions in porous materials (e.g., the volumes of different size pores within the range from 1 to 900 μm effective pore radii). Complimentary Automated Instrument Software, Release 2000.1, and Data Treatment Software, Release 2000.1 is used to capture, analyze and output the data. More information on the TRI/Autoporosimeter, its operation and data treatments can be found in The Journal of Colloid and Interface Science 162 (1994), pgs 163-170, incorporated here by reference.

As used in this application, determining Pore Volume Distribution involves recording the increment of liquid that enters or leaves a porous material as the surrounding air pressure changes. A sample in the test chamber is exposed to precisely controlled changes in air pressure. The size (radius) of the largest pore able to hold liquid is a function of the air pressure. As the air pressure increases (decreases), different size pore groups drain (absorb) liquid. The pore volume of each group is equal to this amount of liquid, as measured by the instrument at the corresponding pressure. The effective radius of a pore is related to the pressure differential by the following relationship.

Pressure differential=[(2)γ cos Θ]/effective radius

where γ=liquid surface tension, and Θ=contact angle.

Typically pores are thought of in terms such as voids, holes or conduits in a porous material. It is important to note that this method uses the above equation to calculate effective pore radii based on the constants and equipment controlled pressures. The above equation assumes uniform cylindrical pores. Usually, the pores in natural and manufactured porous materials are not perfectly cylindrical, nor all uniform. Therefore, the effective radii reported here may not equate exactly to measurements of void dimensions obtained by other methods such as microscopy. However, these measurements do provide an accepted means to characterize relative differences in void structure between materials.

The equipment operates by changing the test chamber air pressure in user-specified increments, either by decreasing pressure (increasing pore size) to absorb liquid, or increasing pressure (decreasing pore size) to drain liquid. The liquid volume absorbed (drained) at each pressure increment is the cumulative volume for the group of all pores between the preceding pressure setting and the current setting.

In this application of the TRI/Autoporosimeter, the liquid is a 0.2 weight % solution of octylphenoxy polyethoxy ethanol (Triton X-100 from Union Carbide Chemical and Plastics Co. of Danbury, Conn.) in distilled water. The instrument calculation constants are as follows: p (density)=1 g/cm³; γ (surface tension)=31 dynes/cm; cos Θ=1. A 0.22 μm Millipore Glass Filter (Millipore Corporation of Bedford, Mass.; Catalog # GSWP09025) is employed on the test chamber's porous plate. A plexiglass plate weighing about 24 g (supplied with the instrument) is placed on the sample to ensure the sample rests flat on the Millipore Filter. No additional weight is placed on the sample. The remaining user specified inputs are described below. The sequence of pore sizes (pressures) for this application is as follows (effective pore radius in μm): 1, 2.5, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900, 800, 700, 600, 500, 450, 400, 350, 300, 275, 250, 225, 200, 180, 160, 140, 120, 100, 90, 80, 70, 60, 50, 40, 30, 20, 15, 10, 5, 2.5, 1, 2.5, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 225, 250, 275, 300, 350, 400, 450, 500, 600, 700, 800, 900. This sequence starts with the sample dry, saturates it as the pore settings increase (1^stabsorption), and then subsequently drains the sample of all volume above an effective pore radius of 1.0 μm (desorption), and then finally saturates it again as the pore settings increase a second time (2^ndabsorption). The equilibrium rate is set at 5 mg/minute. No stop radius is specified.

In addition to the test materials, a blank condition (no sample between plexiglass plate and Millipore Filter) is run to account for any surface and/or edge effects within the chamber. Any pore volume measured for this blank run is subtracted from the applicable pore grouping of the test sample. This data treatment can be accomplished manually or with the available TRI/Autoporosimeter Data Treatment Software, Release 2000.1.

In regards to wet fibrous structure (web) collapse, the characteristic pore size distribution of the 2^ndabsorption portion of the testing sequence is analyzed, since absorption in the 1^stabsorption portion of the testing sequence can sometimes vary based on how the dry fibrous structure contacts the wetted filter (influenced by dry fibrous structure texture, embossing, etc.). Thus, after the desorption portion of the testing sequence, the sample, already wetted once, is expected to be in better hydraulic contact with the porous filter (due to lower fiber and fibrous structure (web) modulus when wet).

The TRI/Autoporosimeter reports the weight (mg) of liquid absorbed/desorbed from each pore group as chamber pressure is step changed according to the prescribed testing sequence. From this data, the liquid density, and the weight of the original, dry sample, the ratio of pore volume/sample weight can be calculated. This value can be reported as mm³/mg of dry sample mass. Similarly, the pore volume/dry sample weight over a specified pore size range (e.g., 20-500 μm) can be calculated by simply summing the reported pore volumes of each pore setting included in that range and dividing by the dry sample mass. These data treatments are conducted manually based on the output of the Automated Instrument Software, Release 2000.1.

B. Fiber Diameter Test Method

A fibrous structure comprising hydroxyl polymer fibers of appropriate basis weight (approximately 5 to 20 grams/square meter) is cut into a rectangular shape, approximately 20 mm by 35 mm. The sample is then coated using a SEM sputter coater (EMS Inc, PA, USA) with gold so as to make the fibers relatively opaque. Typical coating thickness is between 50 and 250 nm. The sample is then mounted between two standard microscope slides and compressed together using small binder clips. The sample is imaged using a 10× objective on an Olympus BHS microscope with the microscope light-collimating lens moved as far from the objective lens as possible. Images are captured using a Nikon D1 digital camera. A Glass microscope micrometer is used to calibrate the spatial distances of the images. The approximate resolution of the images is 1 μm/pixel. Images will typically show a distinct bimodal distribution in the intensity histogram corresponding to the fibers and the background. Camera adjustments or different basis weights are used to achieve an acceptable bimodal distribution. Typically 10 images per sample are taken and the image analysis results averaged.

The images are analyzed in a similar manner to that described by B. Pourdeyhimi, R. and R. Dent in “Measuring fiber diameter distribution in nonwovens” (Textile Res. J. 69(4) 233-236, 1999). Digital images are analyzed by computer using the MATLAB (Version. 6.3) and the MATLAB Image Processing Tool Box (Version 3.) The image is first converted into a grayscale. The image is then binarized into black and white pixels using a threshold value that minimizes the intraclass variance of the thresholded black and white pixels. Once the image has been binarized, the image is skeletonized to locate the center of each fiber in the image. The distance transform of the binarized image is also computed. The scalar product of the skeltonized image and the distance map provides an image whose pixel intensity is either zero or the radius of the fiber at that location. Pixels within one radius of the junction between two overlapping fibers are not counted if the distance they represent is smaller than the radius of the junction. The remaining pixels are then used to compute a length-weighted histogram of fiber diameters contained in the image.

All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.

While particular embodiments/examples of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.