HK1054767A - Method for regulating agglomeration of elastic material - Google Patents

Description

Process for regulating agglomeration of elastomeric materials

The present application claims priority as follows: U.S. provisional application nos.60/166,348 filed on 19/11/1999 and 60/222,812 filed on 4/8/2000.

Background

People rely on disposable absorbent articles to ease their lives.

Disposable absorbent articles, including adult incontinence articles and diapers, are generally manufactured by combining several components. These components typically include a liquid permeable topsheet; a liquid impermeable backsheet attached to the topsheet; and an absorbent core positioned between the topsheet and the backsheet. When the disposable article is worn, the liquid permeable topsheet is adjacent to the body of the wearer. The topsheet allows passage of body fluids to the absorbent core. The liquid impervious backsheet helps prevent leakage of fluids held in the absorbent core. Absorbent cores are generally designed to have desirable physical properties, such as high absorbent capacity and high absorption rate, so that body fluids can be transported from the skin of the wearer to the disposable absorbent article.

Some disposable absorbent articles are constructed with various types of elasticized waistbands and elasticized leg bands or leg cuffs. One method of constructing elasticized regions is to incorporate elastic strands, bands or other materials into the disposable absorbent article. For example, elastic strands have been laminated between polymer film layers and/or woven or nonwoven fabric layers to provide such regions. Folded layers have also been employed to surround or encapsulate selected lines of material. These folded layers have been employed to surround elastic strands in the waist bands, leg sleeves and inner shield sleeve assemblies of disposable diapers and other disposable absorbent articles. The polymeric film, layer of woven or nonwoven fabric and/or folded layer may be an integral part of the topsheet and/or backsheet discussed above, or may be a separate component attached to the topsheet and/or backsheet.

To incorporate the elastomeric material into the prepared product, a spool of material is typically placed on an unwind stand. For example, a spool of elastic thread placed on an unwind stand is continuously unwound in the machine direction and the thread is attached to a substrate, such as a base material layer, to provide a substrate composite. As noted above, examples of base materials include, but are not limited to, polymeric films and/or woven or nonwoven fabrics. If segments of elastic strands are adhered or bonded to adjacent segments of elastic strands, the adjacent segments may be difficult to pull apart when the bobbin is unwound. In fact, the thread pieces can break, resulting in wasted downtime on the production machine.

What is needed is a method for handling spools, reels, spindles or other containers of elastomeric material such that the material remains substantially unagglomerated; a spool, reel, spindle or other container in which adjacent pieces of material remain substantially unagglomerated; and composite substrates and absorbent articles made using the treated elastic material such that the material remains substantially unagglomerated before the material is used as a raw material.

SUMMARY

We have determined that adjacent segments of elastic material agglomerate when the material is exposed to water or moisture. For example, if the elastic strands are prepared at a location different from where the strands are used as raw materials, the elastic strands must be transported. During shipping, storage, or other steps, the elastic strands may be exposed to an amount of water or moisture sufficient to cause agglomeration of adjacent segments of the strands. If the strands agglomerate, they may break more often when used as raw materials in a manufacturing process, such as a typical high speed disposable absorbent article manufacturing process running at about 1000 feet per minute or greater. Accordingly, the present invention relates to regulating agglomeration of elastomeric materials by regulating the exposure of the materials to water or moisture.

One method having features of the invention includes the steps of: providing substantially unagglomerated elastic strands; and adjusting the exposure of the strand to water or water vapor such that the strand remains substantially unagglomerated.

In one representative embodiment, the exposure of the elastic strand to water or water vapor is regulated such that the specific humidity around the strand does not exceed about 0.017 pounds-mass of water vapor per pound-mass of dry air, specifically about 0.01 pounds-mass of water vapor per pound-mass of dry air, and more specifically about 0.005 pounds-mass of water vapor per pound-mass of dry air during the following period: the storage of address lines in which the elastic wire is prepared, the transportation between the address in which the elastic wire is prepared and the address in which the elastic wire is used as a raw material, the storage of address elastic wires in which the elastic wire is to be used as a raw material, or some combination thereof. In some aspects of the invention, the thread is used as a raw material to produce a composite substrate comprising the thread or an absorbent article comprising the thread.

Another exemplary embodiment, wherein the exposure of the elastic strand to water or water vapor is regulated, comprises controlling the temperature around the strand or around a container containing the strand such that the strand remains substantially unagglomerated before the strand is used as a starting material. In one aspect, the temperature is controlled such that it does not exceed about 55 ° F. By adjusting the temperature, the maximum humidity that can be achieved is adjusted (i.e., as the air temperature decreases, the air's ability to retain moisture decreases).

In another embodiment, a method wherein the elastic strand's exposure to water or water vapor, including controlling the humidity around the strand or around a container containing the strand, is regulated such that the strand remains substantially unagglomerated prior to use as a starting material. In one aspect, the humidity is controlled such that it does not exceed about 0.017 pounds-mass of water vapor per pound-mass of dry air, specifically about 0.01 pounds-mass of water vapor per pound-mass of dry air, and more specifically about 0.005 pounds-mass of water vapor per pound-mass of dry air.

In some embodiments of the invention, the elastic strand that regulates exposure to water or water vapor comprises a polyester, a polyurethane, a polyether, a polyamide, a polyacrylate, a polyester-b-polyurethane block copolymer, a polyether-b-polyurethane block copolymer, or a polyether-b-polyamide block copolymer.

Another method having features of the invention includes the steps of: providing an elastic strand that has been prepared by a step comprising extruding, spinning, or other steps of preparing the strand; and adjusting the strand's exposure to water vapor such that the agglomeration index value (defined below) is no more than about 10 grams per strand, specifically no more than about 20 grams per strand, more specifically no more than about 25 grams per strand, more specifically no more than about 30 grams per strand, and is suitably substantially zero when it is used as a raw material on a production machine. In another aspect, the production machine is a machine that introduces one or more elastic strands into a composite substrate or disposable absorbent article.

In another aspect of the invention, regulating the exposure of an elastic strand to water or water vapor comprises the steps of: the strands are placed into a container comprising a barrier material resistant to water vapor permeation, and the container is closed such that the strands remain substantially unagglomerated.

In another method of the invention, at time t₁Closing the container comprising the shielding material for a time t₁After the time of the first production line and before the time of transporting the line from the address of the first production line to the address of the line for use. In another aspect, at time t₁And time t₂And a specific humidity around the wire of no more than about 0.017 pounds-mass of water vapor per pound-mass of dry air, specifically about 0.01 pounds-mass of water vapor per pound-mass of dry air, and more specifically about 0.005 pounds-mass of water vapor per pound-mass of dry air, for a time t₂Is the time for the first opening of the sealed container including the shielding material.

In another aspect, the shielding material comprises polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, nylon, cellulose, or combinations thereof.

In some versions of the invention, the container including the barrier material is closed by heat sealing the container, the barrier material, or both.

Another method having features of the invention includes placing a desiccant material with the wire prior to closing the container including the barrier material (e.g., by heat sealing the barrier material). In another aspect, the desiccant material comprises calcium chloride, calcium sulfate, silica gel, molecular sieves, Al₂O₃Or some combination thereof.

Other exemplary embodiments include the steps of: displacing any air and water vapor mixture from the interior of the container comprising the barrier material with an inert dry gas prior to closing the container (e.g., by heat sealing the barrier material); placing the wetness indicator inside the container comprising the barrier material prior to closing the container (e.g., by heat sealing the barrier material); or both.

Other exemplary embodiments of the present invention include elastic strands that are treated to retain the strands substantially unagglomerated by adjusting the exposure of the strands to water or moisture, and composite substrates and disposable absorbent articles made using such elastic strands.

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.

Drawings

Fig. 1 shows a cross-sectional view of an apparatus for preparing an elastic strand.

Fig. 2 shows a cross-sectional view of an apparatus for preparing an elastic strand.

Fig. 3 shows an image of a slit-open bobbin of wire (specifically, Glospan1060, available from globem manufacturing Company, having an office's business at Massachusetts, Fall River) after the bobbin has been exposed to 20% relative humidity and a temperature of 72 ° F for 45 days.

Fig. 4 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 3 days.

Fig. 5 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 5 days.

Fig. 6 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 2 weeks.

Fig. 7 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 4 weeks.

Fig. 8 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 35 days.

FIG. 9 shows an image of a slit-open bobbin (specifically, Glospan 1060) of a wire that has been placed over a container containing 100g CaSO after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for two weeks₄And sealing after displacing the air/water mixture inside the bag with substantially dry nitrogen.

FIG. 10 shows an image of a slit-open bobbin (specifically, Glospan 1060) of wire that has been placed on a bobbin containing 100g CaSO after the bobbin has been exposed to 80% relative humidity and a temperature of 100 ° F for 35 days₄And sealing after displacing the air/water mixture inside the bag with substantially dry nitrogen.

Fig. 11 shows an image of a slit-open spool of wire (specifically, Glospan770, available from globem manufacturing Company, having an office's business at Massachusetts, Fall River) after the spool has been exposed to 80% relative humidity and a temperature of 100 ° F for four weeks.

Fig. 12.a. and 12.b. show images of a slit-open spool of wire (specifically, Glospan 1120, available from Globe Manufacturing Company, having an office business in Massachusetts, Fall River) after the spool has been exposed to 80% relative humidity and a temperature of 100 ° F for 15 days.

Fig. 13.a., 13.b., 13.c. and 13.d. show images of cut-open spools of wire that were tested using a tensile testing apparatus for measuring agglomeration index values (see below).

Detailed description of the invention

The present invention relates to regulating agglomeration of elastomeric materials by regulating the exposure of the materials to water or moisture. In some versions of the invention, adjusting agglomeration reduces, minimizes, or eliminates line breaks on production machines that use the line as a raw material. Some representative embodiments of the present invention are discussed in the following paragraphs.

The elastic strands may be made in a variety of ways including, but not limited to, extrusion and spinning. In an extrusion process, as shown in FIG. 1, polymer chips, pellets, granules, or other solid forms 10 are placed in a hopper 12. Solid polymer is fed from the hopper to the chamber 14. The polymer is continuously advanced through the chamber by rotating the screw 16. As the polymer advances through the chamber, the temperature and pressure are such as to melt and densify the solid polymer. Some heat is generated by friction, but typically an external heat source 18 is also used to heat the polymer. The molten polymer is then forced through a die 20 to obtain a strand, continuous fiber, ribbon or filament having the desired structural shape. Possible cross-sectional shapes include, but are not limited to, circular, trilobal, polygonal, rectangular, ribbon-like, or elliptical. Further, the threads may have various cross-sectional dimensions, cross-sectional areas, and/or other physical measurements (e.g., denier or dtex; see examples below). As discussed below, the present invention covers elastomeric materials that are susceptible to agglomeration due to the action of water or moisture. The strand cools and solidifies after leaving the extruder.

In addition to using the polymer as a feedstock, one or more monomers or prepolymers may also be added to the extruder in the form of chips, granules, pellets or other solid forms. The monomer or prepolymer may be added together with a compound that promotes polymerization. The polymerization is carried out in the extruder chamber, but may or may not be complete before the material exits through the die. If the polymerization is incomplete, some polymerization may occur after the material is extruded. Also, some monomers or prepolymers may not end up reacting to become part of the polymer chain in the line.

Many materials can be extruded to obtain elastic strands. The present invention relates to materials that are elastic but are susceptible to attack by water or moisture (e.g., by hydrolysis). Examples of materials from which such elastic strands may be derived include, but are not limited to: polyesters, polyurethanes, polyethers, polyamides, polyacrylates, or combinations thereof, including random, block, or graft copolymers such as polyester-b-polyurethane block copolymers, polyether-b-polyurethane block copolymers, and/or polyether-b-polyamide block copolymers. As mentioned above, the monomer or prepolymer precursor may be added to an extruder to obtain a polymeric material of the type just cited.

Crosslinking agents may also be used when preparing the elastic strands. To the extent that the polymeric chains are cross-linked, it is more likely that the cross-linking reaction will be initiated after the material has been extruded. This may be done, for example, in a separate processing step after the extrusion of the wire.

After the line leaves the extruder, it may be subjected to additional processing steps. These processing steps may occur at the following locations: at some point between the extrusion of the wire and the first winding of the wire on the spool, spindle, or reel. Alternatively, one or more of these processing steps may be performed after the wire has been wound for the first time. After the spool of elastic thread is prepared, it may be later unwound and handled in some manner before it is wound again.

Additional processing steps include, but are not limited to, the following. Air may be directed onto the line exiting the die to increase the cooling rate. A scrubbing step may be included to remove impurities from the thread by exposing the thread to soap or a cleaning agent. A lubricant may be applied to the wires to reduce friction between the wires or between the wires and the device. Possible lubricants include, but are not limited to, vegetable or mineral oils, suitably refined petroleum products, silicone-based materials, or surfactants. A stretching step may be included to help orient the polymer to produce desired physical properties. In one example of a single drawing step, the wire is directed to two sets of rollers. The wire passes through a first set of rollers moving at a first speed and then through a second set of rollers moving at a second speed, the second speed being greater than the first speed. The difference in speed between the first and second sets of rollers increases the tension on the thread, thereby helping to orient the constituent polymer of the thread, change the physical dimensions of the thread, or cause other changes.

After these or other additional processing steps, the wire is wound for storage or transport to another location. During this and other steps, in which the spools, spools of elastic strand are unwound and then wound, the strand may be treated with various additives, such as detergents, lubricants, or dyes.

In addition to the examples of extrusion processes discussed above, various spinning processes may be used to produce elastic strands or fibers. Typically, these processes require dissolving the polymer in solution or melting the polymer.

In the melt spinning process, as shown in fig. 2. The polymer chips, particles, pellets, or other solid forms 30 are heated by a heated metal grid 32 or other heating means. The resulting molten polymer 34 is pumped under high pressure through a plate 38 called a spinneret. The plate generally defines a plurality of apertures. The molten polymer overflows the face of the spinneret, typically into air, and solidifies. A number of such threads 40 may be joined together to form a cable or rope-like structure comprising a plurality of threads.

The polymer is typically melted by contacting a heated grid in the form of a steel tube, which is heated electrically or otherwise. The molten polymer may be delivered to and through the spinneret using a metering pump 36, or a combination of a metering pump and a booster pump. Alternatively, an extrusion screw may be used to assist in melting the polymer, and metering the resulting molten polymer to and through a spinneret.

Typically, the threads or filaments overflow from the face of the spinneret into the air and begin to cool. Air jets or air blasts directed towards the overflow line may be used to accelerate the cooling process. After the strands or filaments have moved sufficiently to achieve cure, they are further processed. As noted above, additional processing steps include, but are not limited to, scrubbing, lubricating, or stretching the wire or wires. FIG. 2, for example, shows a lubrication disc and groove 42 for applying lubricant to one or more wires. After the process is complete, the thread-in this case the cable-or the rope-is wound on a reel, spindle, spool, or take-up reel 44 of the winding station. The wire may pass through one or more rollers 46 before being wound.

Other spinning processes include wet spinning, wherein a solution of the polymer or polymer derivative overflows from a spinneret into a liquid that coagulates the polymer or polymer derivative to form a thread; and dry spinning, in which a solution of the polymer is spilled into air or an inert atmosphere, and the solvent is evaporated therein, thereby forming a filament or thread.

Typically, the same polymeric or monomeric materials used to extrude the elastic strands are also used to spin the elastic strands. As discussed above, the present invention relates to such a thread which is elastic but susceptible to erosion by water or moisture. Examples of monomeric or polymeric materials from which such threads may be derived are discussed above. Also, a crosslinking agent may be used. Also, crosslinking can be performed on the strands or after the filaments have overflowed the spinneret.

Other descriptions of processes for making wires are given in various documents, such as U.S. patent nos.4,340,563 and 3,692,618, which are incorporated herein by reference in their entirety. It should be understood that the above discussion gives examples of ways to make elastic strands. The present invention is not limited to these examples, but may be used in conjunction with other processes for making elastic materials that are susceptible to attack by water or moisture such that adjacent pieces of the material adhere or bond to each other, thereby causing agglomeration.

If the elastic thread is prepared at an address different from the location where the thread is used as a raw material, the elastic thread must be transported. The line may be stored for a period of time prior to shipping. After delivery but before use as a raw material, the line may be stored for a period of time. Even if the elastic thread is prepared at the site where the thread is used as a raw material, the thread must be stored for some time. Depending on the time of year, the location where the strand is prepared, the location where the strand is used as a raw material, the method of transportation, the time consumed between spinning, extruding, or other operations to prepare the filament and the use of the strand as a raw material, and other factors, the elastic strand may be exposed to sufficient water or moisture to cause agglomeration.

Before referring to a figure that illustrates that moisture can cause segments of elastic material to join, adhere, or bond to one or more adjacent segments, it is advantageous to discuss some terms. "Peak load" or "peak load value" as discussed herein represents one of: (a) the load applied on the strand segments as they are pulled from spools of elastic strand that have been slit in the machine direction, measured in grams (discussed below in the section entitled agglomeration index values); or (b) the tensile load applied to the wire as measured in grams when the wire breaks or fails (discussed below and in prior pending U.S. patent application No. 60/166348[ attorney docket No.15,427], which is claimed for priority and incorporated by reference in a manner consistent herewith). It will be appreciated that other measurements may be used to characterize the effect of water or moisture on the tendency of adjacent segments of the elastic strand to agglomerate, or the strength characteristics of the strand. The "elongation" in the introduction discussion refers to the change in length per unit length under peak load. Typically, elongation is quoted in percent. The term specific humidity generally refers to the mass of vapor carried by a unit mass of vapor-free gas. The term specific humidity generally refers to the mass of vapor carried by a unit mass of vapor-free gas. As used herein, "specific humidity" refers to the mass of water vapor carried by a unit mass of non-vaporous gas, which is typically air. The term relative humidity generally refers to the ratio of the partial pressure of vapor to the vapor pressure of a liquid under gas pressure. It is usually expressed on a percentage basis, such that 100% relative humidity means that the gas is saturated with vapor and 0% relative humidity means that the gas is free of vapor. As used herein, "relative humidity" is the ratio of the partial pressure of water vapor to the vapor pressure of water at the temperature of the gas, which is typically air. For the purposes of this document, "humidity" means a measure of the amount of water vapor in a gas, typically air, and, unless otherwise specified, means specific humidity and/or relative humidity. The term dew point generally denotes the temperature at which the vapor-gas mixture must cool-at a constant humidity-to become saturated. As used herein, "dew point" means the temperature at which a vapor-gas mixture must cool-at a constant humidity-to become saturated, the gas typically being air.

Comparison of the two figures gives a visual example of agglomeration behaviour. FIG. 3 shows an image of a cut-open spool of Glossan 1060, which is a bullet material manufactured by Globe manufacturing company, having an office commercial establishment in Massachusetts, Fall River. Glossan 1060 includes polyester-b-polyurethane block copolymers. The cross-sectional dimensions of the wire were about 0.2mm and 1.0mm, resulting in about 0.2mm²Cross-sectional area of. The spool itself comprises a hollow cylinder around which the wire is wound, the cylinder having a radius of 7.5cm and a length of 28 cm. The wire is wound around the hollow cylinder in a helical or spiral fashion, with the outer surface of the wound wire extending radially outward from the surface of the hollow cylinder or core, a distance of about 3.5cm from the surface of the cylinder or core. Before the bobbin is slit open, the bobbin, in its wound form, is placed in an environment in which the temperature is 72 ° F and the relative humidity is about 20%. An air humidity scale at atmospheric pressure showed that these conditions corresponded to about 0.004 lb-mass ("1 b)_m") water vapor per 1b_mThe air is dried. See, for example, WARREN L.MCCABE AND JULIANC.SMITH.UNIT OPERATIONS OF CHEMICAL ENGINEERING, 748 (3 rd edition, 1976). After 45 days of exposure to these conditions, the spools, after being cut open, remain substantially unagglomerated.

FIG. 7 also shows an image of a cut-open spool of Glosspan 1060, but in this case the spool was exposed to 80% relative humidity, 100 ℃ F. for 35 days. These conditions correspond to about 0.0341b_mWater vapor per 1b_mThe air is dried. As can be seen in this image, the segments of thread have been bonded or connected to adjacent segments of thread such that sheet-like agglomerates are formed. If the spool of agglomerated elastic thread is unwound during the production of the article, the thread segment is more likely to break when unwound from the spool as it may be attached to one or more adjacent segments. By adjusting the amount of water or water vapor to which the thread is subjected during one or more processing and handling steps that occur after the thread has been extruded, spun, or otherwise preparedThe invention solves this problem.

In one aspect of the invention, one or more processing and/or treatment steps are performed after the extrusion, spinning or other strand manufacturing process in a controlled humidity environment. This is typically accomplished by performing one or more of these steps in a room, compartment, or other enclosure, wherein the amount of humidity in the respective enclosure is controlled such that it does not exceed a selected set point. The set point corresponds to a desired specific humidity or relative humidity. Control generally involves first detecting or measuring a value corresponding to the specific humidity or relative humidity in the enclosure. Typically the means for detecting or measuring moisture is in the vicinity of the elastic thread. The sensed or measured value is communicated to a controller, computer, or other device that compares the sensed or measured value to a set point value. If the detected or measured value differs from the set point value, a control action is carried out such that the specific humidity or relative humidity in the enclosure is forcibly adjusted to be at or below the desired specific humidity or relative humidity.

Typically, the specific or relative humidity is forcibly adjusted by passing the air/water vapor mixture through cooling coils such that the temperature of the mixture is reduced below the dew point of the mixture. As a result of this cooling process, a portion of the water vapor condenses on the coils and is removed as a liquid, thereby reducing the humidity. The humidity is forcibly adjusted to the desired level by passing a sufficient amount of the air/water vapor mixture through the cooling coil and then feeding the dehumidified air into the enclosure. After the water vapor has been condensed and removed by this cooling process, the air may be heated to increase the dry bulb temperature. As used herein, "dry bulb temperature" means the temperature of the air/water vapor mixture as indicated by a thermometer placed in the mixture. Thus, "controlled humidity" as used herein refers to an environment in which the specific humidity and/or relative humidity is controlled, and if the air is heated after the air/water vapor mixture is dehumidified to increase the dry-bulb temperature, an environment in which the dry-bulb temperature is also controlled or adjusted.

The air/water vapor mixture may be drawn from inside the enclosure, dehumidified, and then recycled back to the enclosure; or it may be extracted from outside the enclosure, dehumidified, and fed into the enclosure; or both. For example, if the enclosure is constructed near a winding station to which the elastic thread is continuously directed, there is an opening in the enclosure to allow the thread to enter and be wound. If the manufacturing environment is hot and humid, a slight positive pressure is maintained inside the enclosure to reduce the amount of hot, humid air that enters the enclosure through the opening. In this case, some amount of the air/water vapor mixture outside the enclosure must be dehumidified and fed into the enclosure to replace the air/water vapor mixture inside the enclosure that escapes from the opening due to the positive pressure.

Without controlling the humidity so that it is at or below the set point value, the air within the room or enclosure may be cooled to the temperature set point so that the maximum specific humidity does not exceed certain levels. A chart of air humidity at atmospheric pressure can be used to select the appropriate temperature set point. For example, at a temperature of 40 ° F, even at 100% relative humidity, the specific humidity is about 0.0061b_mWater vapor per 1b_mThe air is dried. As discussed above, the elastomeric material pair is about 0.0041b_mWater vapor per 1b_mThe dry air specific humidity exposure for 45 days did not produce significant agglomeration. Thus, "controlled temperature" as used herein means an environment in which the temperature is controlled to some value to regulate the amount of water vapor experienced by the elastic strands.

As noted above, one embodiment of the present invention involves moisture control of one or more processing and/or treatment steps after extrusion or spinning. Alternatively, the temperature of the processing and/or treatment steps may be controlled to limit the ability of the air to retain moisture. For example, the step in which the elastic strand is first wound on a winder may be performed in a controlled humidity or controlled temperature environment. The upstream or downstream processing steps of the first winder may also be carried out in a controlled humidity or controlled temperature environment. As used herein, "first winder" means a winder on which the thread is wound for the first time after being extruded, spun or otherwise prepared; "upstream" refers to those processing steps that occur after the extrusion or spinning line, but before the first winder, and "downstream" refers to those processing steps that occur after the first winder. If one or more additional processing steps are performed after the first winding step at a separate unwinding/winding station (i.e., a station in which the elastic strands are unwound, processed, and rewound in some manner), these one or more additional processing steps may be performed in a controlled humidity or controlled temperature environment. To the extent that the spool of elastic thread is stored prior to use or shipment, the spool may be stored in a controlled humidity or controlled temperature environment. If the elastic strand is to be shipped to another location, the steps of preparing and packaging the elastic strand for shipment-perhaps including another step in which the elastic strand is unwound and then rewound-may also be conducted in a controlled humidity or controlled temperature environment. The step of transporting or conveying the elastic strands themselves may be carried out in a controlled humidity or controlled temperature environment.

All of these steps-wrapping, storing, preparing and packaging for shipping (if shipping is required), shipping, and perhaps restocking where the thread is to be used as a raw material location-can be conducted in a controlled humidity or controlled temperature environment such that when it is used as a raw material on a production machine (e.g., a machine for making disposable absorbent articles), the agglomeration index value does not exceed about 10 grams per thread, specifically about 20 grams per thread, more specifically about 25 grams per thread, more specifically about 30 grams per thread.

However, in some embodiments of the invention, one or more steps need not be performed in a controlled humidity or controlled temperature environment. For example, the elastic strands may be placed in a container that includes a shielding material. As used herein, "barrier material" means a material that is resistant to moisture vapor transmission. The step of placing the elastic thread in a container comprising a shielding material, i.e. packaging the elastic thread for storage or transport, may be performed in many ways. The spool of elastic thread, or pallet of spools of elastic thread, may be wrapped or encased by a shielding material, such as a suitable shrink wrap material. Alternatively, the spool of elastic wire, or a pallet of spools of elastic wire, may be placed in a flexible plastic bag comprising a shielding material. Or the elastic strands may be placed into a box or carton comprising a shielding material such as a flexible plastic bag liner lined with water vapor permeation resistance or a flexible plastic bag containing water vapor permeation resistance. It should be understood that the present invention encompasses other containers that include shielding material.

If the elastic thread is placed in a container comprising a shielding material while in a low humidity environment, the microenvironment in the container immediately surrounding the elastic thread corresponds to the low humidity environment. In another aspect of the invention, the air/water vapor mixture within the container may be displaced by a substantially dry gas to create a microenvironment around the centerline of the container (see below). Or a desiccant may be added to adsorb/absorb any moisture in the container. After closing the container, subsequent processing steps may be performed so that the humidity or temperature outside the container is not adjusted. The container should not be opened until the line is to be used as a raw material in the production process.

Many methods may be used to package the elastic strands. The elastic strands may be wound on a first winder in a controlled humidity or controlled temperature environment and then extracted, conducted or transported to a controlled humidity or controlled temperature environment for packaging. Alternatively, the elastic strand may be wound on a first winder and then quickly extracted, conducted or delivered to a controlled humidity or controlled temperature environment for packaging.

The spool of elastic wire, or pallet of spools of elastic wire, is placed in a container comprising a shielding material in a controlled humidity or controlled temperature environment. Suitable barrier materials resistant to water vapor permeation include, but are not limited to, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, nylon, cellulose, or combinations thereof. The density, thickness, characteristics, and/or other physical properties of the shielding material (e.g., water solubility in the selected shielding material) may be selected such that the moisture mass transfer through the shielding material does not result in agglomeration of the material or exceed the selected value during the expected shipping and/or storage time of the spool, reel, or spindle of the elastic strand. The container is then closed in such a way as to minimize the amount of water vapour that may reach the line of packaging during subsequent storage and/or transport steps. For example, if the container comprising the shielding material is a flexible polyethylene bag or other flexible, vapor-resistant plastic bag, the container may be heat sealed after the spools of elastic wire, or a pallet of spools of elastic wire, are inserted into the bag. Alternatively, the spool of elastic thread, or pallet of spools of elastic thread, may be placed into a carton or case lined with a shielding material such as a polyethylene bag, and the bag heat sealed after the spool of elastic thread is in place.

In another aspect, the method of the present invention further includes placing a desiccant material adjacent to the elastic strands prior to closing, e.g., heat sealing, the container including the barrier material. The desiccant acts to preferentially adsorb or absorb moisture as the container allows moisture to permeate into and around the elastic strands. Thus, the desiccant helps to maintain the humidity within the container at a humidity that minimizes strength degradation.

Examples of useful desiccants include calcium chloride, calcium sulfate, silica gel, molecular sieves, Al₂O₃And the like. Typically, a desiccant is placed in the receptacle, which allows moisture to pass into the interior of the receptacle and into contact with the desiccant, but separates the desiccant from the elastic strands. Examples of receptacles are webs comprising natural fibres-typically containing cellulose as the main component-pouches or nonwoven materials, such as polyethylene or polypropylene nonwovens. In selecting the type and amount of desiccant to be used, various physical properties of the desiccant can be evaluated (e.g., the amount of water removed per unit mass of desiccant; the residual concentration of water in the air after the air/moisture mixture has been contacted with the desiccant under specified conditions). Furthermore, after selecting a shielding material having a particular thickness and density, one can predict the amount of water vapor that will diffuse through the shielding material during the expected shipping and/or storage time. The type and amount of desiccant can then be selected such that the predicted amount of water vapor permeating the barrier material does not exceed the capacity of the desiccant to adsorb/absorb water vapor.

In another aspect, the invention further includes the step of displacing the air/water vapor mixture within the container including the barrier material with a dry, inert gas prior to closing the container. For example, after a pallet of elastic thread spools has been placed in the container, a flexible conduit may be used to direct dry nitrogen gas to the interior of the container. After sufficient time has elapsed to allow the air/water vapor mixture to be displaced from the interior of the container, the conduit is removed from the container, and the container is then closed. This displacement step may be used in combination with the following steps: the desiccant is placed with the elastic strands prior to closing the container. The converting step may or may not be performed in a controlled temperature or controlled humidity environment.

In another aspect, the moisture detector is placed with the elastic wire prior to closing the container including the shielding material. When the bag or container is opened, most likely after having been shipped to the purchaser of the elastic strand, the moisture detector may be checked to determine if the moisture within the container exceeds certain values. Alternatively, if the bag or container comprising the shielding material is transparent, the detector may be inspected without opening the container. If the humidity exceeds certain values, the bag or container may be rejected and returned to the provider. Alternatively, samples from the shipment can be tested immediately. If the strength characteristics of the wire are deemed acceptable, then it is acceptable to use the shipment as a raw material. An example of a suitable moisture detector is a moisture detector corresponding to catalog number HC-10/60-200, available from Omega Engineering Inc. of Connecticut, Stamfod. The indicator is capable of detecting a relative humidity of 10-60%.

The step of placing the moisture detector with the elastic thread may be used in combination with: placing a desiccant with the elastic strand prior to closing the container including the shielding material; replacing the air/water vapor mixture inside the container comprising the shielding material with a dry, inert gas prior to closing the container; or both.

In some embodiments of the invention, the spool of elastic thread is stored in: where the line is prepared, where the line is used as a raw material, or both. If the wire is not packaged during these storage steps and the wire is to be stored for more than 10 days, particularly more than 20 days, and particularly more than 30 days, the room, facility, or area in which the wire is stored may be a controlled humidity or controlled temperature environment. However, as noted above, all processing and handling steps after extruding or spinning the thread may be performed in a controlled humidity or controlled temperature environment-the total time between extruding or spinning without piping and using the thread as raw material-to minimize or eliminate strength degradation. Or the elastic strands may be packaged such that the "microenvironment" inside the container comprising the barrier material has a low moisture content (i.e., low humidity), thus allowing subsequent processing steps to occur such that there is no need to control the environment outside the container.

Elastic strands processed or treated in accordance with the present invention can be incorporated into a wide variety of composite substrates and disposable absorbent articles. Examples of such composite substrates and/or disposable absorbent articles are described in the following documents: U.S. patent No. 4,940,464, entitled "disposable incontinence garment or athletic pant," which is incorporated herein by reference in its entirety; U.S. patent No.5,904,675 entitled "absorbent article with improved elastic edge and containment system," which is incorporated herein by reference in its entirety, columns 7, lines 7-34 discuss the use of elastic strands with containment flaps, and columns 9, line 29 to column 10, line 36 discuss elastic elements; U.S. patent No.5,904,672 entitled "absorbent article having improved waist region dryness and method of manufacture", which is incorporated herein by reference in its entirety, discusses elastic leg elements at column 11, line 39 to column 12, line 2; and U.S. patent No.5,902,297 entitled "absorbent article containing a collection conduit," which is incorporated herein by reference in its entirety. It should be understood that the present invention is applicable to other structures, composites, or products incorporating one or more elastic strands.

Examples of methods and apparatus useful in the present invention for making elastomeric laminate webs (i.e., composite substrates incorporating elastic strands for the purposes of the present invention) are found in the following documents: U.S. patent No.5,964,973 entitled "method and apparatus for making elastomeric laminate web," which is incorporated herein by reference in its entirety in accordance with the present specification. It should also be understood that the present invention provides examples of methods and apparatus for introducing elastic strands into a composite substrate, but that the present invention may be used in conjunction with other methods and apparatus for preparing composite substrates.

Testing

Agglomeration index value

The agglomeration index value was measured as follows. First, a rotational axis of the wire is obtained, typically comprising the wire wound around a core. The core is generally cylindrical, having an axial dimension and a radial dimension. The wire is cut or cut with a razor, knife, or other cutting tool such that the cuts or cuts are parallel to the axial dimension of the core. The depth of the cut or kerf may be equal to the distance from the surface of the spool of wire to the surface of the core around which the wire is wound, or some increment thereof. Figure 3 shows an image of a rotating shaft in which the rotating shaft of elastic strands, after cutting in the axial dimension, is unwound in the form of pieces of substantially unagglomerated strands. Fig. 7 shows an image of a rotating shaft in which the rotating shaft of elastic strands, after being cut in the axial dimension, unravel in the form of substantially agglomerated strand segments (e.g., sheet-like agglomerates in which one strand segment is joined to one or more adjacent strand segments).

If the wound wire, after slitting, unravels in a substantially unagglomerated form, the agglomeration index value is not measured (if the individual wire does not adhere to any of its neighbors, the measurement proves to be more difficult). Instead, the agglomeration index value equals zero. However, if the wound wire, after slitting, unravels in a substantially agglomerated form, the core and agglomerates are placed on a support near the tensile testing apparatus. For our measurements, an Sintech tensile tester, model 3108-. The tensile tester is improved by attaching a spring clip to a length of wire. The wire is then attached to a tensile tester so that the tester can operatively measure the load in grams required to pull 1 or 2 wire segments from the wire agglomerate, the wire segments being held by closed spring clips (see fig. 13.a., 13.b., 13.c., and 13. D.).

The cut-open spindle of the wire is placed on the support so that the cut or cut of the wound wire is opposite the gripper that is used to pull a predetermined number of wire segments away from the wire agglomerate (for our experiments, 1 or 2 wire segments, see fig. 13.a., 13.b., 13.c. and 13. D.). Before starting the test, the clamps are operated so that a predetermined number of segments are held by the clamps, the clamps being operated to minimize the initial spacing between wire segments to be pulled apart from adjacent wire segments. The tester is then turned on so that the clamps are pulled away from the cut-open wire material surface. The clamps are pulled apart in a direction substantially perpendicular to the surface of the slit-opened wire material and at a speed of 300 mm/min. When the spring clamp is pulled away from the surface of the strand agglomerate due to the action of the tensile tester, 1 or 2 strands held by the closing spring clamp are pulled away from the strand agglomerate and separated. The tensile tester measures the load in grams required to pull a predetermined number of thread segments apart from adjacent thread segments. The agglomeration index value corresponds to the average of five to ten repetitions of this test, the load being measured as the peak load occurring during the test (i.e. the maximum load detected during the test). If two lines are used when conducting the test, the peak load (in grams) is divided by two to obtain the gram value for each line.

In some cases, the agglomeration index value of a line located near: the winding of the wire is around the surface of the spool; the core surface around which the wire is wound ("core position"); and/or approximately halfway between the core surface and the spool surface of the wire ("intermediate position"). The agglomeration index values of the wires at the middle and core positions were measured by: the spool and peel wire, or layer of wire, is cut or sliced until the wire (or wires) is exposed at the desired test location for completion of the test as described below. Also, as shown in fig. 13.c, if pulling the strand from the strand agglomerate moves the core (which typically does not happen), an object can be inserted into the core around which the elastic strand is wrapped.

Although the present invention has been described in considerable detail and with reference to certain versions thereof, other variations are possible. The spirit and scope of the appended claims should not be limited to the description of the specific versions contained herein.

Examples

Example 1

Glospan1060, a spool of elastic strand comprising a polyester-b-polyurethane block copolymer, available from Globe Manufacturing Company. The number "1060" corresponds to the denier of the thread, i.e., about 1060 denier or about 1060 grams per 9000 meters of thread. The elastic strands have been coated with a lubricant. When received, the wire is wound around the hollow core. The core had a radius of 7.5cm (radial dimension) and a length of 28cm (axial dimension). The wire is wound around a core to form a tube comprising a helically or spirally wound wire. The outer surface of the conduit extends radially outwardly from the core surface, a distance of about 3.8cm from the core surface. The tube length of the helically or spirally wound wire is about the same as the length of the core. (Note: the strands may be systematically stacked to form a shape other than a tube or cylinder comprising a single strand or multiple strands.) the cross-sectional area of a single strand is about 0.2mm²(calculated by multiplying the cross-sectional dimensions of the lines: 1.0mm by 0.2 mm).

The spool, when received from the manufacturer, comprises substantially unagglomerated wire. The spool of Glospan1060 was placed in a controlled environment, the temperature controlled to a value of about 100 ° F and the relative humidity controlled to a value of about 80%. The spools were exposed to these conditions for various times as follows: 3 days, 5 days, 2 weeks, 4 weeks, and 35 days. After each of these conditioning times has elapsed, the spools are sent to a room having a temperature of about 72-75 ° F and a relative humidity of about 50%. The bobbin is then cut integrally along its length with a razor blade. Typically, the bobbin is slit within 30 minutes after removal from an environment having a temperature of about 100 ° F and a relative humidity of about 80%. Typically, the blade is inserted such that the edge of the blade penetrates from the surface of the bobbin to a depth of about 0.5-1 cm. The razor is then pulled along the axial dimension of the spool, from one end of the spool to the other. This slitting process is repeated, typically until a position close to the core is reached. The spool exhibited varying degrees of agglomeration depending on the time of exposure to a temperature of about 100 ° F and a relative humidity of about 80%. After 3 days of exposure, most of the shafts remained substantially unagglomerated, but the edges of the shafts began to show some agglomeration (see FIG. 4; agglomeration at the edge lines is referred to in the figure as "edge blocking"). Similar behavior was seen after 5 days of exposure (see FIG. 5; agglomeration at the edge line is referred to in the figure as "edge blocking"; "open to air" means that exposure to the prevailing conditions-a temperature of about 100F and a relative humidity of about 80% -was not conditioned; unless otherwise stated, the bobbin of elastic material was placed in a conditioned environment such that the material was exposed to the prevailing conditions). The spool of Glossan 1060 that had been cut in its entirety after exposure to a temperature of about 100 ℃ F. and a relative humidity of about 80% for 2 weeks showed increased agglomeration, containing the sheet-like structures from the cutting process. (see fig. 6). In other words, cutting the spool as a whole produces a peeled onion-like structure comprising a layered sheet of agglomerated strands. The Glospan1060 spool exposed to a temperature of about 100 ℃ F. and a relative humidity of about 80% for 4 weeks and 35 days again showed agglomeration throughout the spool shaft. (see figures 7 and 8, respectively). The sequence of images shown in figures 4, 5, 6, 7, and 8 determines that exposure to certain conditions causes the axes of rotation of the elastic material to agglomerate (i.e., the strand segments begin to bond to at least some portion of adjacent strand segments).

Example 2

Glospan770, a spool of elastic thread comprising a polyester-b-polyurethane block copolymer, was obtained from the Globe Manufacturing Company. The number "770" corresponds to the denier of the thread, i.e., about 770 denier or about 770 grams per 9000 meters of thread. The elastic strands have been coated with a lubricant. The wire is wound around a hollow core. The core had a radius of 7.5cm (radial dimension) and a length of 28cm (axial dimension). The wire is wound around a core to form a tube comprising a helically or spirally wound wire. The outer surface of the conduit extends radially outward from the core surface, a distance of about 3.5cm from the core surface. The tube length of the helically or spirally wound wire is about the same as the length of the core. (Note: the strands may be systematically stacked to form a shape other than a tube or cylinder comprising a single strand or multiple strands.) the cross-sectional area of a single strand is about 0.1mm²(calculated by multiplying the cross-sectional dimensions of the lines: 0.2mm by 0.5 mm).

The spool, when received from the manufacturer, comprises substantially unagglomerated wire. The spool of Glossan 770 was placed in a controlled environment, temperature controlled to a value of about 100F and relative humidity controlled to a value of about 80%. After exposing the spool to these conditions for 4 weeks, it was removed from the environment. The spool was then sent to a room with a temperature of about 72-75F and a relative humidity of about 50%. The bobbin is then cut integrally along its length with a razor blade. Typically, the bobbin is slit within 30 minutes after removal from an environment having a temperature of about 100 ° F and a relative humidity of about 80%. The blade is inserted so that the edge of the blade penetrates from the surface of the bobbin to a depth of about 0.5-1 cm. The razor is then pulled along the axial dimension of the spool, from one end of the spool to the other. As shown in fig. 11, severing the spool of wire in this manner creates a first sheet of agglomerated wire (this first sheet being located at the furthest position of the core). Repeated cuts made in a similar manner produce additional panels of agglomerated strands. Cutting the spool as a whole in this manner produces a peeled onion-like structure comprising a layered sheet of agglomerated strands. Thus, four-week exposure to a temperature of 100 ° F and a relative humidity of 80% causes line agglomeration.

Example 3

Glossan 1120, spool or reel of elastic thread comprising polyester-b-polyurethane block copolymer, available from Globe Manufacturing Company. The number "1120" corresponds to the denier of the thread, i.e., about 1120 denier or about 1120 grams per 9000 meters of thread. The elastic strands have been coated with a lubricant. The wire is wound around a hollow core. The core had a radius of 8cm (radial dimension) and a length of 11cm (axial dimension). The wire is wound around a core to form a tube comprising a helically or spirally wound wire. The outer surface of the conduit extends radially outwardly from the core surface, a distance of about 6cm from the core surface. The tube width of the helically or spirally wound wire was 7.5 cm. (Note: the strands may be systematically stacked to form a shape other than a tube or cylinder comprising a single strand or multiple strands.) the cross-sectional area of a single strand is about 0.22mm²(calculated by multiplying the cross-sectional dimensions of the lines: 0.22mm by 1.0 mm).

The spool, when received from the manufacturer, comprises substantially unagglomerated wire. The spool of Glossan 1120 was placed in a controlled environment, temperature controlled to a value of about 100 ° F and relative humidity controlled to a value of about 80%. After exposing the spool to these conditions for 15 days, it was removed from the environment. The spool was then sent to a room with a temperature of about 72-75F and a relative humidity of about 50%. The spool is then systematically slit along its length using a razor blade. Typically, the bobbin is slit within 30 minutes after removal from an environment having a temperature of about 100 ° F and a relative humidity of about 80%. The blade is inserted so that the edge of the blade penetrates from the surface of the bobbin to a depth of about 0.5-1 cm. The razor is then pulled along the axial dimension of the spool, from one end of the spool to the other. As shown in fig. 12.a. and 12.b, cutting the spool of wire in this manner produces a first sheet of agglomerated wire (this first sheet being located at the furthest position of the core). Repeated cuts made in a similar manner produce additional panels of agglomerated strands. Cutting the spool as a whole in this manner produces a peeled onion-like structure comprising a layered sheet of agglomerated strands. Thus, a fifteen day exposure to a temperature of 100 ° F and a relative humidity of 80% causes line agglomeration.

Example 4

The process described in example 1 for integrally cutting the spool of wire was carried out on another gloss pan1060 spool. In this case, the spool of Glossan 1060 was placed in an environment with a temperature of about 72 ℃ F. and a relative humidity of about 20%. After 45 days of exposure to these conditions, spools of Glospan1060 were removed from the environment and cut as described in example 1. The spool of Glospan1060 was cut in this manner to unravel the spool, as shown in FIG. 3, producing a substantially unagglomerated wire. Thus, exposure to lower amounts of water or moisture reduces or eliminates agglomeration of the strands.

Example 5

Spools from Glossan 770 and Glossan 1060 are available from Globe manufacturing company. The elastic thread has been coated with a lubricant for each of these bobbins. The approximate dimensions of the core, the helical or spiral tube of the wound wire around the tube, and the cross-sectional area of the individual wires are given in the above examples of Glossan 1060 and Glossan 770.

Each spool comprises substantially unagglomerated wire when received from a manufacturer. Both one spool of Glossan 770 and two spools of Glossan 1060 were placed in a controlled environment, with temperature controlled to a value of about 100 ° F and relative humidity controlled to a value of about 80%. After 2 weeks exposure to these conditions, a spool of Glossan 1060 was removed from the controlled environment. Using the agglomeration index value test described above, the agglomeration index values were measured near two position lines: a bobbin surface; and the surface of the core. After 2 months of exposure to these conditions, both the remaining spool of Glossan 1060 and the remaining spool of Glossan 770 were removed from the controlled environment. Using the agglomeration index value test described above, the agglomeration index values were measured for Glospan1060 near two position lines: a bobbin surface; and the surface of the core. Agglomeration index values for Glossan 770 were measured at three locations, as described below.

Table 1 gives the results for Glossan 1060.

TABLE 1

Measurement of adhesion between 80% RH, 100 ℃ F. aged Glospan1060 lines
					(using Sintech, 300mm/min, 75 ℃ F.)
					Sample (I)	Aging time	Position of the thread	adhesion/Peak load (gm)	Remarks for note
Fresh Glossan	0	Surface of	0	The thread falling from the spindle without sticking
					Fresh Glossan	0	Core	0	No adhesion
					Aged Glossan	2 weeks	Surface of	30	Adhesion of the components
	2 weeks	Core	76	Adhesion of the components
Aged Glossan	2 months old	Surface of	43.5	Adhesion of the components
						2 months old	Core	133	Adhesion of the components

The "fresh" Glospan1060 (i.e., examined and tested as received from the manufacturer without placing the spool of wire into a controlled environment at a temperature of 100 ° F and a relative humidity of 80%) did not exhibit agglomeration (i.e., did not exhibit "blocking"). When the "fresh" Glospan1060 spool was cut as described above, the wire was spread out as substantially unagglomerated wire. Therefore, the agglomeration index value (i.e., the peak load measured using the agglomeration index value test described above) is equal to 0.

After exposure to 100 ° F temperature and 80% relative humidity for two weeks, the Glospan1060 bobbin showed agglomeration behavior near the surface of the conduit and the surface of the core. In addition, the agglomeration index values measured at these locations were measured as 30 and 76 grams per wire, respectively (the agglomeration index values are referred to as "blocking/peak load" in table 1).

After two months of exposure to 100 ° F temperature and 80% relative humidity, the Glospan1060 bobbin showed agglomeration behavior near the surface of the conduit and the surface of the core. In addition, the agglomeration index values measured at these locations were measured as 43.5 and 133 grams per heel line, respectively.

Glospan770 spool exposed to a temperature of 100 ° F and a relative humidity of 80% for two months, showing agglomeration behavior at the following positions: near the spool surface, halfway between the spool surface and the core surface, and the core surface. In addition, the agglomeration index values measured at these locations were measured as 24.5, 42.5 and 71 grams per thread, respectively.

The data show that the continuously exposed lead wire or wire segment to water or moisture adheres or bonds to adjacent wire or wire segments, thus forming an agglomerated wire that requires additional force to separate.

Example 6

Spools from Glospan1060 are available from Globe Manufacturing Company. The elastic thread has been coated with a lubricant for each of these bobbins. The approximate dimensions of the core, the helical or spiral tube of the wound wire around the tube, and the cross-sectional area of the individual wires are given in the above example of Glossan 1060.

Each spool comprises substantially unagglomerated wire when received from a manufacturer. Both eight spools of Glospan1060 were placed in a controlled environment, with temperature controlled to a value of about 100 ° F and relative humidity controlled to a value of about 80%. The four spools were placed in a controlled environment such that they were exposed to the prevailing conditions. Four spools were first prepared according to one version of the invention to adjust the exposure of the wire to water or water vapor. Before placing these four spools into a controlled environment, each spool was placed into a polyethylene bag having a size of 60cm/30cm/10cm and a thickness of 4 mils (i.e., 0.0004 inches). After the spool was placed in the bag, 100g of desiccant, in this case CaSO, was added₄And putting into a bag. In this test, the desiccant was first placed in a non-woven polypropylene receptacle, and then the desiccant-containing receptacle was placed in a polyethylene bag containing a bobbin. Dry nitrogen (gas purity 99.99% nitrogen) is then fed to the interior of the bag. This can be done as follows: one end of a tube was connected to a nitrogen cylinder, the other end of the tube was placed in the bag, and a valve on the cylinder was opened. In largeAfter about 5 minutes, the tube was withdrawn from the interior of the bag and the bag was sealed using a heat sealing device. The room temperature was about 72-75F and the relative humidity was about 50% with the spools sealed into polyethylene bags containing desiccant. After the four bobbins were prepared according to one aspect of the present invention, they were also placed in a controlled environment with temperature controlled to a value of about 100 ° F and relative humidity controlled to about 80%.

After about 5 days (114 hours), the Glospan1060 spool that had been opened to the conditioned environment and the Glospan1060 spool that had been sealed into a polyethylene bag containing desiccant were removed from the controlled environment. Each of these bobbins was systematically slit as described in the above embodiments. Furthermore, the mechanical properties of the wire section were measured close to the surface of the wound wire tube, in the mid-way region between the wire tube surface and the core surface, and the core surface. In addition, the degree of agglomeration that occurred (described in the table as "blocking") was observed. This procedure was repeated at about 234 hours (about 10 days), 14 days, and 35 days. The results of these measurements are shown in table 2 (see below).

TABLE 2

Effect of aging on mechanical Properties of Glossan 1060
								Aging at 80% RH, 100 ℃ F. for various times
(spindle of aged Glossan 1060. samples were taken from the surface, middle and core of the spindle and then tested)
								(T.S.: tensile strength, peak load gm; Elong. -%) elongation at break%
								Aging for 114hr	Lines from the surface		From the middle of the line		Wire from the core		Remarks for note
Sample (I)	T.S.gm	Elong.％	T.S.gm	Elong.％	T.S.gm	Elong.％
								Open to the air	535	1043	591	1250	597	1226	Edge adhesion
Sealed/dryDrying machine	586	1273	616	1408	605	1380	CaSO without discoloration4Ion(s)
Aging for 234hr
								Open to the air	416	977	444	1116	493	1084	Some adhesion
Sealed/dried	600	1239	596	1181	604	1260	～20％CaSO4Color change is carried out; no adhesion
								Aging for 14 days

TABLE 2 continuation

Open to the air	475	998	493	1091	515	1142	Some adhesion
								Sealed/dried	638	1144	616	1232	606	1217	Color changing CaSO4Ions; no adhesion
								Aging for 35 days
Open to the air	420	997	425	972	474	1024	Adhesion of the components
								*Sealing bag	574	1114	576	1324	562	1271	Most preferably

In a manner consistent therewith. The previously pending applications generally relate to methods and apparatus for regulating the exposure of elastic strands to water or water vapor, thereby regulating the deterioration of strand strength properties due to the action of water or water vapor on the strands. The results in table 2 of the present application show that the strength is deteriorated due to the action of moisture. For a Glospan1060 bobbin that is open-laid for the prevailing conditions (i.e., a relative humidity of about 80% and a temperature of about 100 ℃ F.) in a controlled environment, the tensile strength (as expressed by the peak load value, in grams, corresponding to the load at which the strand breaks) generally decreases with time of exposure to the prevailing conditions. Any reduction in strength that may occur for the spool of Glossan 1060 that has been sealed into a polyethylene bag containing desiccant is less than that of a spool of Glossan 1060 placed open for the prevailing conditions in a controlled environment (as shown by Table 2, desiccant discoloration indicates that the desiccant may have approached saturation, thus reducing its water absorption capacity). Thus, the peak load value (i.e., tensile strength) of the elastic material sealed into the desiccant-containing polyethylene bag is significantly higher than that of an elastic material exposed to the conditions prevailing in a controlled environment (i.e., a relative humidity of about 80% and a temperature of about 100 ° F).

In addition, sealing the Glossan 1060 bobbin in a desiccant containing polyethylene bag significantly reduced agglomeration. As shown in figures 5, 6 and 8 (these images correspond to spools from which individual wire segments were removed for measuring the mechanical properties shown in table 2), those spools of Glospan1060 that were left open for the prevailing conditions agglomerated (or "blocked") in a controlled environment. However, those spools sealed in desiccant-containing polyethylene bags, experienced significantly less agglomeration. For example, the split spool shown in FIG. 9 shows that 100 grams of CaSO has been present in a controlled environment at a temperature of about 100F and a relative humidity of about 80% for two weeks before being placed in the controlled environment₄The polyethylene bag of (1) was sealed with a spool of Glospan 1060. The figure shows that the lines are substantially unagglomerated. On the other hand, FIG. 6 shows a cut-open spool of Glossan 1060 that has been left open to the prevailing conditions in a controlled environment for two weeks. Forming a string of flake-like agglomerates.

Similar comparisons were found at day 35. Glospan1060 exposed to prevailing conditions in a controlled environment undergoes significant agglomeration (see FIG. 8). (ii) a Glospan1060, wherein,sealing into a container containing 100g of CaSO₄In the polyethylene bag of (1), less if any agglomeration was experienced (see fig. 10).

Example 7

LYCRA 940, a spool of elastic cord comprising a polyether-b-polyurethane block copolymer, is available from Dupont, corp, with a commercial establishment at the office of Delaware, Wilmington. The number "940" corresponds to the decitex of the line. The wire is wound around a hollow core. The core had a radius of 7.5cm (radial dimension) and a length of 8.5cm (axial dimension). The wire is wound around a core to form a tube comprising a helically or spirally wound wire. The outer surface of the conduit extends radially outwardly from the core surface, a distance of about 9cm from the core surface. The tube length of the helically or spirally wound wire is about the same as the length of the core. (Note: the strands may be systematically stacked to form a shape other than a tube or cylinder comprising a single strand or multiple strands.) the cross-sectional area of a single strand is about 0.2mm²(calculated by multiplying the cross-sectional dimensions of the lines: 0.2mm by 1.0 mm).

When received, the spools of LYCRA 940 have some agglomeration. The slit bobbin had a peeled onion-like structural sheet of agglomerated thread. The agglomeration index values measured near the conduit surface, midway between the conduit surface and the core surface of the wire, and the core surface were 19.5, 40, and 35 grams per wire, respectively.

The bobbin was placed in a controlled environment at a temperature of about 100F and a relative humidity of about 80%. The bobbin is exposed to the prevailing conditions in a controlled environment. After having been exposed to these conditions for 1 month, the spools were removed and the agglomeration index values were measured. The agglomeration index values measured near the pipe surface, midway between the pipe surface and the core surface, and the core surface were 27, 53, and 67 grams per wire, respectively. Thus, in LYCRA 940 spools, exposure to these conditions results in increased adhesion between adjacent thread segments. In addition, exposure to these conditions resulted in a reduction in the average peak load value from about 740 grams to about 660 grams.

Claims (28)

1. A process for treating substantially unagglomerated elastic strands so that the strands remain substantially unagglomerated, the process comprising the steps of:

providing substantially unagglomerated elastic strands; and

adjusting the exposure of the strand to water or water vapor such that the strand remains substantially unagglomerated.

2. The method of claim 1 wherein the exposure of the strand to water or water vapor is adjusted such that the specific humidity around the strand does not exceed about 0.01 pounds-mass of water vapor per pound-mass of dry air during: the storage of the thread at the address at which the thread is prepared, the transport of the thread between the preparation of the address of the thread and the address at which the thread is used as a raw material, the storage of the thread at the address at which the thread is used as a raw material, or some combination thereof.

3. The method of claim 2, wherein the thread is used as a raw material to produce a composite substrate comprising the thread or an absorbent article comprising the thread.

4. The method of claim 3 wherein the specific humidity around the wire does not exceed about 0.005 pound-mass water vapor per pound-mass dry air.

5. The method of claim 3, wherein the exposure of the thread to moisture is regulated during the transport of the thread between the address at which the thread is prepared and the address at which the thread is used as a starting material.

6. The method of claim 5, wherein regulating the strand's exposure to water vapor comprises controlling the temperature around the strand or around a container containing the strand.

7. The method of claim 6 wherein the temperature is controlled to a value of no more than about 55 ° F.

8. The method of claim 5, wherein regulating the strand's exposure to water vapor comprises controlling humidity around the strand or around a container containing the strand.

9. The method of claim 7 or 8, wherein the wire comprises a polyester, a polyurethane, a polyether, a polyamide, a polyacrylate, a polyester-b-polyurethane block copolymer, a polyether-b-polyurethane block copolymer, or a polyether-b-polyamide block copolymer.

10. The process of claim 8 wherein the strand's exposure to water vapor is adjusted such that the agglomeration index value of the strand is less than about 20 grams per strand when the strand is used as a raw material to produce a composite substrate comprising the strand or an absorbent article comprising the strand.

11. The process of claim 8 wherein the strand's exposure to water vapor is adjusted such that the agglomeration index value of the strand is substantially zero when the strand is used as a raw material to produce a composite substrate comprising the strand or an absorbent article comprising an elastic strand.

12. The method of claim 1, wherein regulating the line's exposure to water or water vapor comprises the steps of:

placing the wire in a container comprising a shielding material resistant to water vapor penetration; and

closing the container comprising the shielding material.

13. The method of claim 12, wherein at time t₁Closing the container comprising said shielding material for a time t₁After the time of first producing the thread and before the time of transporting the thread from the address where the thread was produced to the address where the thread was used as a raw material.

14. The method of claim 13, wherein at time t₁And time t₂The specific humidity around the line does not exceed 0.017 pounds-mass of water vapor per pound-mass of dry air, time t₂Is the time for the first opening of the closed container comprising the shielding material.

15. The method of claim 13, wherein at time t₁And time t₂At a specific humidity not exceeding 0.01 pounds-mass of water vapor per pound-mass of dry air, around the wire, for a time t₂Is the time for the first opening of the closed container comprising the shielding material.

16. The method of claim 13, wherein at time t₁And time t₂At a specific humidity not exceeding 0.005 pounds-mass of water vapor per pound-mass of dry air, around the wire, for a time t₂Is the time for the first opening of the closed container comprising the shielding material.

17. The method of claim 14, wherein the shielding material is polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, nylon, cellulose, or some combination thereof.

18. The method of claim 17, wherein closing the container comprising the shielding material comprises heat sealing the container, the shielding material, or both.

19. The method of claim 14, further comprising the step of placing a desiccant material with the wire prior to closing the container including the barrier material.

20. The method of claim 19, wherein the desiccant material comprises calcium chloride, calcium sulfate, silica gel, molecular sieves, Al₂O₃Or some combination thereof.

21. The method of claim 18 or 20, further comprising the steps of: displacing any air and water vapor mixture inside the container including the barrier material with an inert dry gas prior to heat sealing the container, the barrier material, or both; the wetness indicator is placed inside the container comprising the barrier material prior to heat sealing the container, the barrier material, or both.

22. The method of claim 17, wherein the elastic strand comprises a polyester, a polyurethane, a polyether, a polyamide, a polyacrylate, a polyester-b-polyurethane block copolymer, a polyether-b-polyurethane block copolymer, or a polyether-b-polyamide block copolymer.

23. The process of claim 14 wherein the strand's exposure to water vapor is adjusted such that the agglomeration index value of the strand is less than about 20 grams per strand when the strand is used as a raw material to produce a composite substrate comprising the strand or an absorbent article comprising the strand.

24. The process of claim 14 wherein said strand's exposure to water vapor is adjusted such that the agglomeration index value of said strand is substantially zero when said strand is used as a raw material to produce a composite substrate comprising said strand or an absorbent article comprising said elastic strand.

25. The method of claim 23 or 24, wherein the tensile strength of the strand is reduced by no greater than about 20% when the strand is used as a raw material to produce a composite substrate comprising the strand or an absorbent article comprising the strand when the strand is produced a first second time.

26. An elastic strand treated by the method of claim 13, 17, 18, 20 or 23.

27. A composite substrate comprising the elastic strand of claim 26.

28. A disposable absorbent product comprising the composite substrate of claim 27.