MX2007014039A - Elastic laminates and process for producing same. - Google Patents

Abstract

A method is provided for producing elastic composite laminates. The laminates contain elastic filaments that are stretched and laminated to at least one facing material. The continuous filaments are laminated to the facing material using a starved slot coat process. The starved slot coat process provides various benefits and advantages including the production of laminates having improved properties.

Description

ELASTIC LAMINATES AND PROCESS TO PRODUCE THEMSELVES BACKGROUND OF THE INVENTION Articles that require a degree of elasticity have been formed by the combination of elastic materials with inelastic, or less elastic, materials through various lamination processes. Often, such composite laminate articles will be able to stretch due to the presence of the elastic material and the particular manner in which the elastic and inelastic materials have been joined together during the lamination process.

Typically, such laminates capable of stretching are formed by the union of the inelastic material to the elastic material while the elastic sheet material is in a stretched condition. After such a joining of the materials, the laminated article is allowed to relax, which results in the folding of the inelastic component in the spaces between the bonding sites on the elastic sheet. The resulting laminate article is then able to stretch to the extent that the inelastic material that folds between the bonding locations allows the elastic material to elongate. Examples of These types of composite laminate articles and materials are set forth in U.S. Patent Nos. 4,720,415 and 5,385,775, each of which is incorporated herein by reference thereto.

In some laminated articles capable of stretching, the elastic filament yarns of continuous filaments are attached to relatively inelastic sheet materials while the elastic yarns are in a stretched condition. Such elastic continuous filaments may, in certain articles, be interleaved between two or more relatively inelastic sheets. Relatively inelastic sheets may include non-woven fabrics formed by meltblowing or spinning of various polymers. Examples of such laminates are shown in U.S. Patent No. 5,385,775; in the patent of the United States of America number 6,057,024; and in the United States of America patent application published US 2002/0104608, which are incorporated herein by reference.

As shown in the '775 patent, the elastic continuous filaments can be extruded on a horizontally moving sheet of material. The filaments continuous are extruded from above the horizontal plane of the sheet material and directly into the material to be joined thereto. In the '024 patent, an alternative embodiment is described in which the continuous filaments are extruded vertically in a downward direction. As the filaments are extruded in a downward direction, the filaments are stretched and then laminated to one or more sheet materials.

In many embodiments in the past, an adhesive was used in order to adhere the elastic filaments of continuous filaments to the sheet materials. In one embodiment, for example, the adhesive was sprayed onto the sheet material before contacting the filaments. Spraying the adhesive material on the sheet materials, however, can have some problems in various applications. For example, spraying devices can be difficult to control leading to over-application of the adhesive or leading to non-uniform coverage of the adhesive on the sheet material, especially at high machine speeds and at low application rates. In fact, over-applying a hot adhesive during a spray process can cause the filament to break and the breakdown of the machine. In addition, since the adhesive has to travel a distance before contacting the sheet material, the adhesives may experience a loss in bonding before contacting the sheet material.

In view of the foregoing, there is presently a need for an improved method for applying an adhesive material between the stretched elastic filaments and a non-woven fabric. A need also exists for a laminate of elastic compound having improved properties due to the way in which an adhesive is applied.

SYNTHESIS OF THE INVENTION In general, the present disclosure is directed to composite elastic materials that include a plurality of elastic continuous filaments attached to at least one non-woven fabric. The non-woven fabric is laminated to the continuous filaments when the filaments are in a stretched state. Therefore, when the filaments are relaxed, the non-woven fabric gathers and allows the entire composite to stretch in at least one direction.

The present disclosure is more particularly directed to a method for applying an adhesive material between the elastic continuous filaments and the non-woven fabric and is directed to composite non-woven materials produced by the process. The adhesive material is applied to the non-woven fabric using a "private" groove coating process in which the adhesive is emitted through the extrusion die groove on the non-woven fabric to form a discontinuous coating. The discontinuous coating contains amorphous elements of the adhesive material. The adhesive material is applied to a surface of the non-woven fabric in a substantially uniform manner in terms of amount per area.

The private coating process provides several benefits and advantages. For example, the process allows control over the placement of the adhesive on the non-woven fabric. In addition, the inventors have discovered that the process provides a very efficient use of the adhesive. In particular, relatively low amounts of adhesive are used which ensure continuous elastic filament bonding to the non-woven fabric, even when the elastic filaments are present in a stretched state. Unexpectedly, the current inventors also discovered that the process produces materials not composite fabrics having a reduced porosity in comparison to similar compounds made in which the adhesive is sprayed onto the non-woven fabric. The relatively low porosity provides several benefits when the composite material is used to construct various items, such as when incorporated into absorbent garments including diapers, underpants, swim briefs, adult incontinence products, feminine hygiene products, bandages and medical covers, and the like.

In a particular embodiment, for example, the present disclosure is directed to a method for producing a composite nonwoven material. The method includes the steps of extruding continuous filaments. The filaments comprise an elastomeric material. The elastomeric material may include, for example, elastic polyesters, elastic polyurethanes, elastic polyamides, elastic copolymers of ethylene and at least one vinyl monomer, elasticized metallocene polyolefins of catalyzed metallocene, and block elastic copolymers.

Once formed, the continuous elastic filaments are stretched and then laminated to the first side of a non-woven fabric. In order to join the stretched laminates to the Non-woven fabric, an adhesive material is applied to the non-woven fabric from an extrusion die groove. The adhesive material forms a discontinuous coating comprising amorphous elements of the adhesive material. The adhesive material can be applied to the first side of the non-woven fabric in an amount of less than about 4.4 grams per square meter, such as from about 0.5 grams per square meter to about 3 grams per square meter. The adhesive material may comprise, for example, a block styrenic copolymer, a random copolymer of a polyolefin, or an amorphous polyalphaolefin. In addition to the above, any suitable hot melt adhesive can be applied in accordance with the teachings of the present disclosure.

During the application of the adhesive material to the non-woven fabric, the non-woven fabric can be configured to contact and slide against the slot on the slot of the extrusion die. The adhesive material can contact the fabric at a viscosity from 500 centipoise to about 50,000 centipoise, such as from about 2,000 centipoise to about 20,000 centipoise. The temperature of the adhesive may vary depending on the particular adhesive material used. In an embodiment, for example, the Adhesive application temperature can be from around 320 degrees Fahrenheit to around 350 degrees Fahrenheit.

In one embodiment, the method may further include the step of laminating the continuous elastic filaments to a second nonwoven fabric. For example, the continuous filaments may be placed between the first non-woven fabric and the second non-woven fabric. The second non-woven fabric can be laminated to the continuous filaments using an adhesive material as described above.

The non-woven fabrics that are laminated to the continuous elastic filaments may vary depending on the particular application and the desired result. Non-woven fabrics can comprise, for example, meltblown fabrics, spunbond fabrics, carded and bonded fabrics, and the like. In one embodiment, for example, the non-woven fabric comprises a spunbonded fabric having a basis weight from about 7 grams per square meter to about 100 grams per square meter, such as from about 10 grams per square meter to around 20 grams per square meter.

Other features and aspects of the present invention are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS A complete and permitted description of the present invention, including the best mode thereof for one skilled in the art, is pointed out more particularly in the remainder of the specification, including reference to the accompanying figures, in which: Figure 1 is a perspective view of an embodiment of a process for producing composite nonwoven materials in accordance with the present invention; Figure 2 is a side view of the system and the process illustrated in Figure 1; Figure 3 is a partial view of an extrusion surface of an exemplary extruder head for extruding continuous elastic filaments; Figure 4 is an enlarged view of a part of the surface illustrated in Figure 3; Figure 5 is a side view of another embodiment of a process that can be used to form the composite nonwovens according to the present invention; Figure 6 is a plan view of an embodiment of a system and process for applying adhesive materials to non-woven fabrics for use in the process of the present invention; Y Figure 7 is a perspective view of an embodiment of a slot in the head of the extrusion die that can be used in the process of the present invention.

The repeated use of reference characters in the present specification and drawings is intended to present the same or analogous features or elements of the invention.

Definitions The term "continuous filaments", as used herein, refers to continuously formed polymeric filament yarns. Such filaments will typically be formed by extruding molten material through a die head having a certain type and arrangement of capillary holes in it.

The term "elastic" or "elasticized", as used herein, refers to the material that, when a tipping force is applied, is extensible or elongated by at least about 60 percent (e.g., at a pressed, stretched length). which is at least about 160 percent of its length without relaxed pressing), and which will recover at least 55 percent of its elongation with the release of the stretching force. For example, a hypothetical example would be a one-inch sample of a material that is elongated to at least 1.60 inches and that when released, will recover to a length of no more than 1.27 inches. Many elastic materials can stretch by much more than 60 percent (for example, more than 160 percent of your relaxed length). For example, some elastic material may stretch 100 percent or more, and many from these they will recover to their relaxed original length substantially, such as, for example, to within 105 percent of their relaxed original length, with the release of the stretching force.

The term "composite nonwoven fabric", "nonwoven composite", "laminate" or "nonwoven laminate", as used herein, unless otherwise defined, refers to a material having at least one elastic material attached to at least one sheet material. In most embodiments, such laminates or composite fabric will have a foldable layer that is bonded to a layer or elastic material such that the foldable layer can be folded between the joint locations. As noted herein, the composite fabric laminate can be stretched to the extent that the collapsible material is folded to the bonding locations allowing the elastic material to elongate. This type of composite elastic laminate is described, for example, in U.S. Patent No. 4,720,415 issued to Vander Wielen et al., Which is hereby incorporated by reference in its entirety.

As used herein the term "non-woven" fabric or fabric means having a fiber structure individual or threads that are intertwined, but not in an identifiable form as in a woven fabric. Non-woven fabrics or fabrics have been formed by many processes such as, for example, meltblowing processes, spin-bonding processes, hydroentanglement, placed by air and weaving processes by carding bonding.

As used herein, the term "meltblown fibers" means fibers of polymeric material that have been generally formed by ejection of a molten thermoplastic material through a plurality of thin-matrix, usually circular, capillaries, such as fused or filaments towards gas streams (for example air), usually hot, converging at high speed, which attenuates the filaments of molten thermoplastic material to reduce their diameter. Hence, the fibers blown by means of fusion can be carried by the gas stream at high speed and be deposited on a collecting surface to form the fabric of blown fibers by means of randomly dispersed melting. Such a process is described, for example, in the patent of the United States of America no. 3,849,241 of Butin et al., Being incorporated by reference in its entirety.

As used herein, the term "spunbonded fibers" refers to small diameter fibers that are formed by extruding a molten thermoplastic material as filaments through a plurality of fine spinner capillaries having a configuration circular or otherwise, with the diameter of the extruded filaments being rapidly reduced as, for example, bonding mechanisms with stretched eductive yarn or other well known spin-linked. The production of spunbonded nonwoven fabrics is illustrated in patents such as, for example, U.S. Patent No. 4,340,563 issued to Appel et al., And U.S. Patent No. 3,692,618 issued to Dorschner. and others The descriptions of which are here incorporated as a reference in their entirety.

DETAILED DESCRIPTION It is understood by one of ordinary skill in the art that the present disclosure is a description of exemplary embodiments only, and is not intended to limit the broad aspects of the present invention.

The present disclosure is generally directed to a method for producing a composite elastic nonwoven material and the material itself. More particularly, the present disclosure is directed to a private slot coating process for applying an adhesive to a viewing material in order to laminate the viewing material to a plurality of stretched filaments. Through the above process, the adhesive has been found to firmly bond the elastic filaments in a stretched state to the viewing material. Once relaxed, the view material is folded into a stretched, bonded laminate having elastic properties in at least one direction.

In one embodiment, during the private slot coating process, the viewing material contacts the groove of the slot extrusion die (or "slot die") as the adhesive is applied to the view. The adhesive is applied to the view at relatively low amounts by forming a discontinuous coating on the non-woven material. Even at relatively low rates of application of the adhesive, the process has been found to surely bond the elastic filaments in view without delamination problems.

In the past, the filaments have been laminated to viewing materials by spraying an adhesive onto the viewing material, as described in the United States of America patent application publication number US 2002/0104608. The process of the present disclosure, however, provides many benefits and advantages compared to an adhesive spray process. For example, the slot coating process can allow lamination at very high inline speeds and can produce laminates that have a very high release resistance. Unexpectedly, the slot coating process produces laminates that have a very low porosity, which makes the material easier to handle during subsequent conversion processes. It is believed that the lowest porosity of the laminate is due to the fact that the adhesive is applied as a discontinuous coating which creates amorphous elements of adhesive as opposed to spray fibrillation which creates fine fibers which may not have much resistance to air flow.

The private slot coating process has been found to efficiently place adhesive on the surface of the viewing material. For example, the adhesive it generally only covers the fibers of the view material and does not bypass the empty areas in the material. In a spraying process, on the other hand, the adhesive is applied all over the substrate and is typically collected in the vacuum areas above the view. When collected in the vacuum areas, the adhesive substantially does not contribute to bond the viewing material to the elastic substrates.

In some applications, the private adhesive coating process has been found to only apply to the surface of the viewing material only on the fibers of the material and to substantially the high points of the material which are generally only places on the material where the view can join the elastic filaments.

Another advantage to the process of the present disclosure in comparison to the spraying processes is that since the adhesive is applied immediately to the substrate as it is emitted from the slot extrusion die, no quenching or quenching of the adhesive occurs before being deposited on the adhesive. material. As such, adhesives with higher or faster curing rates can be used.

In the past, slot coating processes have been described in which a slot die is used to supply the adhesive in order to form laminates. For example, in U.S. Patent No. 5,750,444 issued to Jarrell, which is incorporated herein by reference, a process for producing laminates capable of breathing using a slot matrix is described. In patent 44, the adhesive is described as forming a random porous fibrous tissue. The adhesive is used to join together two or more porous fabrics comprising woven or nonwoven materials to form laminates that remain capable of breathing even after the application of the adhesive between the materials.

In the process of the present description, on the other hand, the laminates are formed in which elastic filaments are stretched and then attached to a viewing material. It has been found that the private slot coating process of the present invention was able to suitably join the stretched filaments in view even at relatively low application rates of the adhesive. Also, it was unexpectedly discovered that the slot coating process as described here increases the porosity of the laminated compared to spray processes. As will be described in more detail below, the increase in porosity facilitates the handling of the laminate in subsequent conversion processes.

With reference to Figures 1 and 2, an exemplary system and process for producing laminates in accordance with the present invention is illustrated. In the embodiment shown in Figure 1, the system can be considered a vertical filament lamination system (hereinafter VFL) since the elastic filaments are formed and stretched in a vertical array. The system illustrated in Figures 1 and 2, however, is merely for exemplary purposes. It should be understood that the process of the present invention can be configured in a horizontal system in which the filaments are cooled and stretched in a horizontal direction. An embodiment of a horizontal system, for example, is illustrated in Figures 1 and 2 of U.S. Patent No. 6,057,024, which is incorporated herein by reference.

As shown in Figure 1, however, the vertical filament lamination system (VFL) 11 is configured vertically. An extruder 15 is mounted to extrude continuous fused filaments 14 downwardly from the die at a skewed angle onto the chill roll placement 12. The chill roll 12 assures proper alignment through the rest of the system as it distributes the filaments. As the filaments move on the surface of the chill roll 12, they are cooled and solidified as they move towards and on the cooled surface of the cooled roll 13. The filaments then move downward in an "S-shaped" progression to a roller 16 and then through the surface of a roller 17, a roller 18 and at the pressure point formed by the pressure point roller 19 and the pressure point roller 20.

The continuous filaments 14 formed in the process can have any desired shape. In one embodiment, for example, the filaments may have a ribbon-like shape. For example, the filaments can have a width from about 0.5 millimeters to about 1.5 millimeters in an unstretched state. The filaments all generally extend in the same direction and are generally parallel to one another. The current number of Continuous filaments used in any particular process may vary depending on the particular characteristics desired in the final product. For example, the formation of the filaments can make a total of more than about 100 threads, such as more than about 200 separate threads. For example, in one embodiment, the formation of the filaments can make a number from about 200 separate threads up to as many as 2600 separate threads. A greater or lesser number of threads, however, is also possible.

As shown in Figure 1, the extruder 15 can be positioned with respect to the first roll 12 such that the continuous filaments face the first roll at a predetermined angle. In some embodiments, an angled, or skewed, orientation provides an opportunity for the filaments to emerge from the die at an angle to the tangent point of the roll resulting in improved spinning, more efficient transfer of energy, and generally in longer life of the matrix. This configuration allows the filaments to emerge from the die and follow a relatively straight path to contact the tangent point on the surface of the roll. The angle between the exit of the extruder matrix and the vertical axis can be so small as a few degrees or as much as 90 degrees. For example, the angle can be around 20 degrees, around 35 degrees, or around 45 degrees, out of the vertical.

The continuous filaments can be combined at the pressure point with various types of views. The views, for example, may comprise non-woven fabrics, woven fabrics including woven fabrics, films, laminates, and the like. In the embodiment described in Figure 1, a first non-woven view joined with yarn 22, and the second non-woven view joined with yarn 24 are combined on opposite surfaces of the continuous filaments to form a bonded laminate 25. In some embodiments, only a view can be used, and in other embodiments it is possible to combine the elastic continuous filaments with three, four, or more layers of sight material.

The joining of the views to the continuous filaments is carried out with an adhesive material. In accordance with the present disclosure, the adhesive is applied to the views using a slot extrusion die. For example, as shown in Figures 1 and 2, a first extrusion die by slot 23 applies an adhesive to the non-woven material 22, while a second slot extrusion die 53 applies an adhesive to the non-woven material 24. As illustrated, the non-woven material 22 contacts the slot extrusion die 23, while the non-woven fabric 24 contacts the slot extrusion die 53 as the adhesive is being dispensed onto the non-woven materials. To ensure adequate contact, for example, the pressure lines 60 and 62 are used.

In one embodiment, the application rates of the adhesive applied to non-woven materials may be relatively low. In fact, the rate of the adhesive is so low that the process can be referred to as a "private" slot coating process. For example, in one embodiment, the adhesive is applied to each of the non-woven materials in an amount of less than about 4.4 grams per square meter (gsm), such as from about 0.5 grams per square meter (gsm) to about 3 grams per square meter (gsm), such as from about 0.8 grams per square meter (gsm) to about 2.5 grams per square meter (gsm).

At such low added rates, the adhesive completely does not coat non-woven materials. Instead, the adhesive forms a discontinuous coating. For example, in one embodiment, the adhesive can form amorphous elements placed on the surface of the nonwoven material. Of particular advantage, the adhesive is mainly applied to the non-woven fabric at elevations on the fabric, which is placed where the fabric is able to bond with the elastic filaments 14. More particularly, the adhesive tends to coat the upper surface of the fibers on the tissue and the collection or bridging of the vacuum areas in the tissue fails. Therefore, little or no adhesive is wasted creating maximum adhesive efficiency.

Although the adhesive forms a discontinuous coating, however, it should be understood that the adhesive is applied in a substantially uniform manner on the surface of the non-woven material in terms of quantity per area.

In general, any suitable slot extrusion die can be used in the process of the present invention. For example, in an embodiment, a slot extrusion die which is commercially available from the Nordson Corporation, Westlake, Ohio. An example of a slot extrusion die from the Nordson is described in U.S. Patent No. 5,750,444, which is incorporated herein by reference.

For exemplary purposes only, an embodiment of a slot extrusion die system is illustrated in Figures 6 and 7. As shown in Figure 6, the system includes an adhesive supply 64 for receiving an adhesive material. The adhesive supply may comprise a container, may comprise a heated container, or may comprise an extruder as particularly shown in Figure 6. The supply of adhesive 64 supplies an adhesive material in a line 66 to a multiple measurement station 68. The measuring station 68 is connected to the slot extrusion die 23 for applying the adhesive material to the non-woven material 22. More specifically, the measuring station 68 is connected to a plurality of line 70A, 70B, 70C, 70D, 70E, 70F, 70G, 70H, 701, 70J, and 70K. The measuring station 68, for example, can be configured to supply adhesive to each of the lines which are in fluid communication with the head of the extrusion die by It should be understood, however, that more or fewer lines may be provided between the measuring station 68 and the slot extrusion die 23.

In one embodiment, the multiple measurement station 68 may include a pumping device placed in association with each of the lines 70A-70K. In this way, each of the lines can operate independently of the others. Therefore, the amount of adhesive flowing through each line can vary from line to line. In other embodiments, however, each line can be supplied with equal amounts of adhesive.

In one embodiment, instead of containing a pumping device, each of the lines is supplied directly from a screw extruder.

With reference to Figure 7, a perspective view of the slot extrusion die 23 is shown with cut-away portions for purposes of illustration of the interior of the extruder. The slot extrusion die 23 includes a slot 72 through which the adhesive material is emitted. In one embodiment, slot 72 is supplied by multiple segments 74. Each segment 74 may be connected, for example, to a corresponding line 70A-70K. By having multiple segments 74, the amount of adhesive dispensed from each location on the slot extrusion die can be varied. In addition, the effective width of the slot 72 can be varied by turning the external lines off or on.

In general, any suitable adhesive material can be supplied on the non-woven materials according to the present invention. In general, the adhesive can be, for example, a hot melt adhesive that is heated before being applied to nonwovens. The adhesive may have an output viscosity of the slot extrusion die from about 500 centipoise to about 50,000 centipoise, such as from about 2,000 centipoise to about 20,000 centipoise. The temperature of the adhesive may vary depending on the adhesive being used. In one embodiment, however, the adhesive can be heated to a temperature from about 250 degrees Fahrenheit to about 400 degrees Fahrenheit, such as from about 320 degrees Fahrenheit to about 350 degrees Fahrenheit.

Adhesive adhesives that can be used in the present invention include various block copolymers, such as styrenic block copolymers. Such block copolymers include, for example, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, styrene-butadiene-styrene block copolymers, and the .

In other embodiments, the adhesive material may comprise a random copolymer of a polyolefin. The polyolefin can be, for example, a polyethylene or a polypropylene.

In still other embodiments, an amorphous polyalphaolefin can be used. In still other embodiments, a metallocene-catalyzed elastomeric resin, such as a polyethylene or polypropylene resin can be used.

Commercially available adhesive materials can be obtained from Bostik, Inc., of the Dow Chemical Company, and various other commercial sources. In some embodiments, the adhesive material may need to be heated before being applied to the non-woven materials.

Adhesives, for example, can be heated to temperatures above 100 degrees Fahrenheit, such as from about 200 degrees Fahrenheit to about 400 degrees Fahrenheit. In some embodiments, the adhesive may be blended with a binder or mixed with other elastomers as desired.

After the adhesive material is applied to the non-woven fabrics 22 and 24, the fabrics are laminated to the elastic filaments 14 while the filaments are in a stretched state. As shown in Figure 1, a take-up roll 21 can be used to receive and unwind the bonded nonwoven / continuous filament / nonwoven fabric 25 material for storage.

Figure 2 illustrates a side view of the vertical filament lamination assembly (VFL), including a support frame 26 with which various components of the system are secured. Reference numerals are used by all figures consistently to indicate the same components in the various views. As shown in Figure 2, the first exterior view roller 27 and the second exterior view roller 28 provide the desired views 22 and 24 to the whole. A support strut 29 holds the pressure point roller 20 in place. The rollers can be seen in the side view that transfers the continuous filaments down to the pressure point, where the filaments combine with the views to form a joined laminate.

The construction of the continuous filaments 14 will now be described in greater detail including the manner in which the filaments are stretched before being attached to the non-woven views in accordance with the present disclosure. As shown in Figures 1 and 2, an elastomeric material is extruded through a die head to initially form the filaments.

Figure 4 depicts an exemplary head of extrusion die 30 with capillary holes 31. In Figure 5, a close view of the head of the die is described. The pattern and diameter of the capillary holes on the die head of the extruder can be varied to provide filaments, with appropriate spacing, without having to use expensive combs, etc., to form a fabric having a correct elastic geometry. The distances di (distance between rows of the centers of the capillary hole), d2 (distance between the centers of the diagonal capillary hole contiguous on opposite rows) and d3 (distance between the centers of the adjacent capillary hole in the same row) can be varied, depending on the particular characteristics desired in the final products. For example, various hole densities can be used in the current process. In an example of 12 filaments per inch, the distance between the center lines of the die holes (di) may be approximately 2.12 millimeters. When a hole density of 18 filaments per inch is used, the distance between the lines of the center of the die hole (di) is approximately 1.41 millimeters.

The rollers leading to the continuous filaments are placed and operated in such a way that they cause the continuous filaments to stretch as they flow vertically through the lamination system. When a number of rollers is employed, each successive roller rotates in a direction opposite to the immediately preceding roller such that the continuous filament yarns are driven out of the roller roller. In addition, the speed of each successive roller can be varied from the preceding roller so as to obtain the desired stretching and elongation characteristics. For example, any particular roller can operate between 1 to 10 times, and more, the speed of any preceding roller. Typically, a separate controller, such as a servo motor or turner, can be used to allow individual speed control for each roller and will drive each individual roller. When the speed is varied, successive rollers can rotate at a faster rate to stretch or lengthen the threads as they move downward in the vertical process. In addition, the continuous filaments are finally reduced to a fiber size of about 0.008 to 0.040 inches in diameter, and in some cases to about 0.015 to 0.020 inches in diameter.

The number of separate rollers used to transport the continuous filaments to the bonding location may vary depending on the particular attributes desired in the final product. In a particular embodiment, at least one roller table - a first cooled (or placed) roller, a second cooled roller, a third uncooled roller, and a fourth uncooled roller - can be used. In another embodiment, only two cooled rolls may be needed before the continuous filaments are supplied to the part of the laminator of the system joining the rolls. views attached by spinning to the continuous filaments in the pressure point roller.

In certain embodiments, the rollers may be coated plasma to provide good release properties. In other incorporationsThe rollers may additionally be engraved or grooved to ensure that the extruded continuous filaments maintain adequate spacing between the individual filaments as the filaments pass over the surface of the rollers and flow through the system. In some embodiments, soft rollers can be used for one or all of the rollers. In the case where the plasma coated rolls are employed, the continuous filaments will not slip as smoothly as when they are uncoated rolls. Plasma coatings grip the yarns and promote increased uniformity of distances between continuous filament yarns.

As suggested, any or all of the rollers can be cooled in such a way that they more quickly harden or temper, the continuous filaments as they proceed through the process. The cooled rolls can be cooled to a controlled temperature of between about 45 degrees Fahrenheit and around 60 degrees Fahrenheit (typically around 45 degrees Fahrenheit or around 50 degrees). Simultaneous tempering and stretching can be optimized depending on the particular stretching characteristics desired in the final product.

In a particular embodiment, the series of rollers (or roller) can be enclosed within a sealed tower structure and air conditioning, with the moisture removed, can be used in order to control the cooling effects of the rollers. For example, the cooled rolls can be cooled to 50 degrees Fahrenheit or less relative to the controlled dew point. In such cases, the temperature at which the rollers are cooled, can significantly be less than 50 degrees Fahrenheit, but with the air conditioning environment, the rollers can remain at 50 degrees Fahrenheit.

Various other mechanisms can be used to anneal the continuous filaments. For example, external air can be forced onto the fibers in order to control the hardening of the fibers. In other incorporations, a large Roller can be used with sufficient surface area in order to temper the fibers.

Maintaining a certain roller speed allows the proper degree of elastic stretching to allow the folds to form the final laminate. The chill roll placement 12 normally rotates at a surface speed in the range of about 3-10 feet per minute, while the first vertically placed cooled roll rotates at around 5 to about 15 feet per minute. The next roller rotates around 7 to about 18 feet per minute, while the last roller, when applied and used, rotates at a speed of about 12 to about 100 feet per minute. These ranges are approximate, and may vary depending on the conditions and configuration of the desired final product.

In a particular embodiment, the first roller can rotate at about 5 feet per minute; the second roller at approximately 6 feet per minute; the third roller at approximately 11 feet per minute; and the fourth roller at approximately 26 feet per minute. Another embodiment uses a first roller speed of 10 feet per minute; a second roller speed of 20 feet per minute; a third roller speed of 40 feet per minute; and a fourth roller speed of 80 feet per minute. In this embodiment, the speed of the pressure point rolls is approximately 75 feet per minute. In another embodiment, the speed of the cooled first roll may be about 400 feet per minute; the speed of the subsequent rollers can be about 750 feet per minute to stretch the continuous filaments; the velocity of the composite material being formed in the pressure point rolls can be about 1500 feet per minute; and a winding roll speed (to allow for relaxed and, therefore, view folding joined with spinning) can be approximately 700 feet per minute.

After passing through a series of rollers and becoming stretched, the continuous filaments are then bonded to the non-woven materials 22 and 24 using the corrugated slot extrusion die described above. The non-woven materials 22 and 24 can be any fabrics or laminates, including meltblown non-woven fabrics, spunbonded non-woven fabrics, carded fabrics or even woven fabrics. In a particular embodiment, a view united with Polypropylene yarn having a basis weight of approximately 0.4 ounces per square yard can be employed.

The system employs pressure point rollers 19 and 20 to apply pressure to the sight coated with adhesive and to the continuous filaments to result in a necessary lamination. The exterior view, which can be between about 20 and 300 pounds per linear inch (pli). A typical union pressure can be around 50 pounds per linear inch or about 100 pounds per linear inch.

The section of the jointer, or pressure point roller (sometimes referred to as "laminator") of the laminating apparatus performs the main stretch on the continuous filaments. The speed ratio of the joining rollers or pressure point relative to the cooling rollers can be varied, and in most cases is between about 2: 1 and 8: 1, and in some it is approximately from 4: 1 to 6: 1.

After joining the views to the continuous filaments to form a laminate bonded with spinning / elastomeric continuous filament / joined with spinning, the laminate is then let relax and contract a condition without stretching or less stretched. The laminate is then wound onto the take-up roller 21 via a surface driven winder. The speed rate of the wire feeder relative to the rolls to be joined results in the relaxation of the stretched continuous filaments and a retraction of the sheet in a folded state as the sheet is wound on the roll. For example, the speed of the wire feeder at the speed of the joining roll can be from about 0.3 to about 1.0, and can be from about 0.5 to 1.0. The shrinkage of the continuous filaments results in a laminated article capable of stretching, folding where the outside views fold between the points of attachment.

The total base weight of the laminate can vary, but in some applications it is between about 2 and about 4 ounces per square yard (osy). In a particular embodiment, the basis weight is between about 2.85 and about 3.2 ounces per square yard.

Various types of compositions and various processing conditions can be used to form the elastic continuous filaments. For example, a polymer Elastic of the Kraton® brand can be supplied in an extruder where the polymer is melted at a controlled temperature of between about 260 degrees and 460 degrees Fahrenheit, and in certain instances at about 385 degrees. In other embodiments, depending on the particular polymer employed, the molten temperature may be from about 470 degrees Fahrenheit to 480 degrees Fahrenheit. The polymer is then extruded through a predetermined number of openings in a die head in a generally downward direction in separate continuous filaments at a pressure of about 300 to 4000 pounds per square inch (psi) (typically from about 1500 to around 2000 pounds per square inch (psi)). As explained below, various configurations of the die hole can be used in the present invention.

A particular class of polymers that can be used in the present process is Kraton® G, a series of polymers distributed by the Shell Chemical Company (now available from Kraton Products U.S.-LLC). Various polymers Kraton® can be used.

However, the present invention is not limited to this or to any particular polymer or material from which the continuous filaments are formed. For example, various materials, including the following, may be used: polypropylene, polyethylene, polyesters, polyethylene terephthalate, polybutane, polymethyldenedione, ethylenepropylene copolymers, polyamides, tetrablock polymers, styrenic block copolymers, polyhexamethylene adipamide, poly- (o-caproamide) , polyhexamethylene-nosbacamide, polyvinyl, polystyrene, polyurethanes, thermoplastic polymers, polytrifluorochloroethylene, ethylene vinyl acetate polymers, polyether esters, polyurethane, polyurethane elastomers, polyamide elastomers, polyamides, viscoelastic hot melt pressure sensitive adhesives, cotton, rayon, jute, and nylon. In addition, such materials can be used to extrude filaments of a single constituent, biconstituent, and bicomponent within the scope of the presently described invention.

Other exemplary elastomeric materials that may be used include polyurethane elastomeric materials such as those available under the brand name TIN of B.F. Goodrich & Co., elastomeric materials of polyamide such as those available under the brand name of PEBAX from the Rilsan Company, and elastomeric polyester materials such as those available under the trademark designation HYTREL, from E.l. DuPont De Nemours & Company However, the invention is not limited to only such elastomeric materials. For example, various latent elastic materials such as Arnitel brand polymers can be used to provide the necessary elasticity characteristics to the continuous filaments.

Likewise, the materials referred to above, and others, can be used in the formation of external views of the laminate currently described. In particular, various elastic polyester materials are, for example, described in U.S. Patent No. 4,741,949 issued to Morman et al., Which is hereby incorporated by reference in its entirety. Other useful elastomeric polymers also include, for example, elastic ethylene copolymers and at least one vinyl monomer such as, for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids, and esters of such acids monocarboxylic The elastic copolymers and the elastomeric fiber formation of these elastic copolymers are described in, for example, U.S. Patent No. 4,803,117, which is also incorporated herein by reference in its entirety.

Various processing aids may also be added to the elastomeric polymers used in the present invention. For example, a polyolefin may be mixed with the elastomeric polymer (e.g., the elastomeric block copolymer A-B-A) to improve the processing of the composition. The polyolefin must be one which, when mixed and subjected to an appropriate combination of high pressure and high temperature conditions, is capable of being extruded in a mixed form with the elastomeric polymer. Useful polyolefin mixing materials include, for example, polyethylene, polypropylene, and polybutene, including ethylene copolymers, propylene copolymers, and butane copolymers. A particularly useful polyethylene can be obtained from the U.S. I. Chemical Company, under the brand name Petrothene NA 601 (also referred to herein as PE NA 601 or polyethylene NA 601). Two or more of the polyolefins can be used. Mixtures capable of extruding polymers elastomers and polyolefins are described in, for example, U.S. Patent No. 4,663,220, which is incorporated herein in its entirety by reference thereto.

With reference to Figure 5, an alternative embodiment of a process for producing laminates in accordance with the present invention is shown. In this embodiment, the vertical filament lamination system (VFL) 111 is also vertically configured. As noted above, however, horizontally configured systems are equally applicable to the present invention.

As shown in Figure 5, an extruder 115 is mounted to extrude continuous fused filaments 114 down from a die at an inclined angle onto a chilled placement roll 112. The chill placing roll 112 ensures proper alignment through the remainder of the die. The conformal system distributes the filaments. As the filaments move on the surface of the chill roll placement 112, they are cooled and solidified as they move toward and on the cooled surface of the cooled roll 113. The filaments then move. down towards the section of the system laminator comprising a pressure point formed by the pressure point roller 119 and a pressure point roller 120.

The continuous filaments are combined at the pressure point with several types of views. In the embodiment described in Figure 5, a first view joined with non-woven yarn 122 and a second view joined with non-woven yarn 124 are combined on opposite surfaces of the continuous filaments to form a bonded laminate 125.

In accordance with the present invention, a slot extrusion die 123 is used to apply a visible adhesive material 122, while a slot extrusion die 153 is used to apply a spun bonding material 124.

In the embodiment illustrated in Figure 5, only two cooled rolls are used as opposed to the large number of cooled rolls shown in Figure 1.

As noted above, the use of an extrusion process by private slot coating as described Above provides several advantages. For example, it was unexpectedly discovered that the process of private slot coating decreases the porosity of the resulting laminate, even at relatively low rates of adhesive application. For example, laminates as shown in Figure 1, can be produced having an air permeability of less than about 400 cubic feet per minute (cfm) per square foot, such as less than about 350 cubic feet per minute. (cfm) per square foot, and in one embodiment, it can be less than about 300 cubic feet per minute (cfm) per square foot. In other embodiments, the air permeability of the laminate can be less than about 250 cubic feet per minute (cfm) per square foot, such as less than about 230 cubic feet per minute (cfm) per square foot. For laminates containing only a single view of laminate material to the continuous filaments, the air permeability can be less than about 300 cubic feet per minute (cfm) per square foot. For example, in particularly applications where the view comprises a spunbond fabric, the air permeability of the composite material may be less than about 250 cubic feet per minute (cfm) per square foot, such as less than about 230 cubic feet per minute (cfm) per square foot.

Having a lower porosity facilitates the handling of the material in subsequent conversion processes. For example, such laminates are well suited for use in the construction of absorbent articles, such as diapers. During the production of a diaper, the elastic laminate typically needs to be cut, manipulated and joined in place. During these steps of the process, the vacuum is often used to transport and move the material. Decreasing the porosity of the material greatly facilitates the ability to manipulate the material using a vacuum or suction force. Finally, the materials made in accordance with the present invention can be processed at very high machine speeds by greatly increasing their production.

The present invention can be better understood with respect to the following examples.

EXAMPLES Test Procedures During the examples that follow, the following tests were performed on the samples that were produced.

Porosity was measured using the STM procedure number 3801. The porosity was measured using a Frazier air permeability tester. The units are cubic feet per minute per square foot.

Elongation was measured by test procedure number STM 529-W. The elongation was tested using any suitable tensile test equipment, such as those available from the Syntech Corporation of Cary, North Carolina, or from the Instrom Corporation, of Canton, Massachusetts.

In a Release Test, a laminate is tested for the amount needed to pull apart layers of the laminate. The release resistance was measured using the procedure number STM 751-W. The samples were tested in the direction transverse to the machine. Any suitable tensile test equipment can be used in order to perform the procedure.

Example No. 1 The following example was carried out in order to determine the effect of the slot coating extrusion process on the porosity of the non-woven laminates.

In this example, two spunbonded fabrics were laminated together. The yarn-bonded fabrics used were made of polypropylene and have a basis weight of 0.42 ounces per square yard.

Nine samples were produced and tested. In the first three samples, an adhesive was sprayed between the spunbond fabrics using a uniform fiber depositor (UFD) available from ITW Dynatec of Hendersonville, Tennessee under the name Dynafiber ™ UFD nozzle. The uniform fiber depositor has one-inch-wide nozzles and contains fourteen capillaries per nozzle. The adhesive used in conjunction with the spray device was the adhesive number H2808-07 obtained from Bostik, Inc., and is a SIS-based adhesive. This particular adhesive is suitable for use in spraying processes.

When the adhesive was sprayed between the spunbonded fabrics, two different uniform fiber depositories were used that were placed adjacent to each weave.

In the rest of the six examples produced, the spunbonded fabrics were laminated together using a slot extrusion die. In particular, the slot extrusion die was model number BC62, obtained from the Nordson Corporation. The slot in the slot extrusion die has an opening of 0.15 inches and is 20 inches wide.

The adhesive used in conjunction with the slot extrusion die was HX9375-01, obtained from Bostik, Inc., which is a blend of polyolefin copolymer. This particular adhesive is somewhat stiff and therefore does not always produce a uniform spray pattern. The adhesive is Well suited for use with slot extrusion dies.

The adhesive was heated before being applied to the non-woven fabrics using the slot extrusion die. At sample numbers 4 and 5 below, the extruder was heated to a temperature from about 340 degrees Fahrenheit to about 345 degrees Fahrenheit. In the remaining samples, however, the extruder was heated to a temperature from around 355 degrees Fahrenheit to around 360 degrees Fahrenheit.

The rates of adhesive added were the same for both the spraying process and the slot extrusion die process, and the range from 1 gram per square meter to 3 grams per square meter.

The following results were obtained: TABLE NO.

As shown above, the laminates formed using the slot extrusion die have a lower porosity than the laminates produced using the spraying device.

Example No. 2 In this example, the elastic laminates were produced according to the present invention and tested for various properties. In order to produce the laminates, a process similar to that illustrated in Figure 5 was used. Specifically, a VFL process that contained two cooling rollers was used. The laminates produced they included two layers of material, namely a coating bonded with yarn adhered to continuous elastic filaments.

The coating comprised a woven fabric bonded with polypropylene yarn having a basis weight of 0.4 ounces per square yard.

The elastic continuous filaments were made of elastomeric block copolymers. Specifically, the elastic filaments were made using the KRATON G2838 polymer available from Kraton Products.

The same two adhesives identified in Example No. 1 were applied to the spin-bonded coating to produce the different samples. In particular, in the first five samples, the HX9375-01 adhesive available from Bostik, Inc., was used while in the remaining seven samples, the adhesive number H2808-07 also obtained from Bostik, Inc., was used. The adhesive was applied to the spunbonded fabric in amounts of from 1.5 grams per square meter to 2.5 grams per square meter to 2.5 grams per square meter. The elastic filaments were laminated to the yarn-bonded fabric at a basis weight of 10 grams per square meter and they were stretched 5.6% when they joined. The temperature of the adhesive was varied depending on the sample.

In one sample, sample 12 below, the adhesive was applied using the uniform fiber depositor as described in example 1 for comparison purposes.

The following results were obtained: TABLE NO. 2 As shown above, the samples were made according to the present invention and had a much lower porosity than in the control sample. As shown in the previous table, the peeling strength of the samples made with the H2808-07 adhesive was generally less than the peel strength of the laminates made with the HX9375-01 adhesive. As explained in example No. 1 given above, the HX9375-01 adhesive is best suited for use with the slot extrusion die.

These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that the aspects of the various incorporations can be exchanged both in whole or in part. In addition, those of ordinary skill in the art will appreciate that the foregoing description is made by way of example only and is not intended to limit the invention thus described in such appended claims.

Claims (20)

R E I V I N D I C A C I ON E S

1. A composite elastic material comprising: continuous elastic filaments generally extending in the same direction, the continuous filaments comprise an elastomeric material, a non-woven fabric having a first side and a second side, the first side of the non-woven fabric being laminated to the elastic continuous filaments, the elastic continuous filaments being laminated to the non-woven fabric in a stretched state so that the fabric does not Woven folds when the continuous elastic filaments are relaxed; Y an adhesive material joined the elastic continuous filaments to the first side of the non-woven fabric, the adhesive material comprises a continuous coating on the first side of the non-woven fabric, the non-continuous coating comprises amorphous elements of the adhesive material, the adhesive material being present on the non-woven fabric in an amount of less than about 4.4 grams per meter square, such as from about 0.8 grams per square meter to about 3 grams per square meter.

2. A composite elastic material as claimed in clause 1, characterized in that the adhesive material comprises a styrenic block copolymer, a random copolymer of a polyolefin, an amorphous polyalphaolefin or mixtures thereof.

3. A composite elastic material as claimed in clause 1, characterized in that the adhesive material comprises a hot melt adhesive.

4. A composite elastic material as claimed in clauses 1, 2 or 3, further characterized in that it comprises a second non-woven fabric having a first side and a second side, the first side of the second non-woven fabric being laminated to the filaments continuous elastic so that the elastic continuous filaments are placed between the first non-woven fabric and the second non-woven fabric; Y an adhesive material joining the elastic continuous filaments to the first side of the second fabric does not woven, the adhesive material comprising a discontinuous coating on the first side of the second non-woven fabric, the non-continuous coating comprising amorphous elements of the adhesive material, the adhesive material being present on the first side of the second non-woven fabric in an amount of less than about 4.4 grains per square meter.

5. A composite elastic material as claimed in clauses 1, 2, 3, or 4, characterized in that the non-woven fabric comprises a knitted fabric having a basis weight of from about 10 grams per square meter to about 20 grams. grams per square meter.

6. A composite elastic material as claimed in clauses 1, 2, 3, 4, or 5, characterized in that the elastomeric material used to form the continuous filaments comprises an elastomer selected from the group consisting of elastic polyesters, elastic polyurethanes, polyamides elastics, elastic copolymers of ethylene and at least one vinyl monomer, polyolefins catalysed as elastic metallocene, and elastic block copolymers.

7. A composite elastic material as claimed in any one of the preceding clauses, characterized in that the composite elastic material has an air permeability of less than about 350 cfm per square foot.

8. A composite elastic material as claimed in any one of the preceding clauses, characterized in that the adhesive material is present on the first side of the non-woven fabric in an essentially uniform manner in terms of quantity per unit area.

9. A composite elastic material as claimed in any one of the preceding clauses, characterized in that the composite elastic material comprises only two layers including a layer of the continuous filaments and the non-woven fabric, the nonwoven comprising a fabric joined with spinning, the composite elastic material having an air permeability of less than about 400 cfm per square foot.

10. A composite elastic material as claimed in any one of the preceding clauses, characterized in that the adhesive only covers the surface fibers of the non-woven fabric and does not deposit appreciably in any pores on the non-woven fabric.

11. A method for producing a composite material as claimed in any one of the preceding clauses, characterized in that it comprises: extruding continuous filaments, the filaments comprise an elastomeric material; stretch the continuous filaments; applying an adhesive material to a first side of the coating material, the adhesive material being applied to the coating material from the slot extrusion die, the adhesive material forms a discontinuous coating comprising amorphous elements of adhesive material; Y laminating the continuous filaments stretched to the first side of the coating material after the adhesive material has been applied.

12. A method as claimed in clause 11, characterized in that it comprises the step of applying an adhesive material to a first side of the second coating material, the adhesive material being applied to the second coating material from a slot extruder; Y laminating the continuous filaments stretched to the first side of the second coating material, the stretched continuous filaments being placed between the prior coating material and the second coating material to form the composite material, the composite having a porosity of less than about 300 cfm per square foot.

13. A method as claimed in clause 12, characterized in that the first coating material and the second coating material comprise spunbond fabrics.

14. A method as claimed in clauses 11-12 or 13, characterized in that the slot extrusion die defines a slot through which the adhesive material is emitted, and where the first side of the coating material makes contact with the groove when the adhesive material is applied to the coating material.

15. A method as claimed in clauses 11-13 or 14, characterized in that the adhesive material has a viscosity of from about 500 cp to about 50,000 cp when the material is applied to the first side of the coating material.

16. A method as claimed in clauses 11-14 or 15, characterized in that the continuous filaments move vertically downwards as they are formed and laminated to the prior coating material.

17. A method as claimed in clauses 11-15 or 16, further characterized in that it comprises the step of relaxing the composite non-woven material after the continuous filaments are laminated to the coating material.

18. A method as claimed in clauses 11-16 or 17, further characterized in that it comprises the step of applying an adhesive material to the first side of a second coating material, the adhesive material being applied to the second coating material from a matrix of slot extrusion, the adhesive material forms a non-continuous coating comprising amorphous elements of the adhesive material; Y laminating the continuous filaments stretched to the first side of the second coating material after the adhesive material has been applied to the second coating material, the stretched continuous filaments being placed between the first coating material and the second coating material to form the material non-woven composite.

19. A method as claimed in clauses 11-17 or 18, characterized in that the continuous filaments are stretched by being carried on at least one roller.

20. A method as claimed in clauses 11-18 or 19, characterized in that the coating material comprises a non-woven fabric having a basis weight of from about 0.2 ounces per square yard to about 1.5 ounces per square yard. SUMMARIZES A method is provided for producing laminated elastic compounds. The laminates contain elastic filaments that are dyed and laminated to at least one coating material. The continuous filaments are laminated to the coating material using a coating process with a private slot. The process of coating with private slot provides several benefits and advantages including the production of laminates having improved properties.