MXPA99010625A - Breathable elastic film/nonwoven laminate - Google Patents

Abstract

A breathable elastic laminate is formed by bonding a film including an elastic water vapor-soluble polymer to a neckable nonwoven web such that when the film is relaxed, the web is in a necked state. The breathable laminate is stretchable in a direction parallel to the narrowing or necking of the web. The laminate possesses excellent water vapor permeability but acts as a barrier to the passage of odor-causing chemicals including ammonia.

Description

NON-WOVEN LAMINATE / ELASTIC FILM WITH BREATHING CAPACITY FIELD OF THE INVENTION This invention is directed to a breathable elastic laminate of a film and a non-woven fabric. The laminate is particularly useful as an outer cover for disposable diapers and other disposable products for personal care. The laminate is also useful for surgical suits with breathing capacity, and other applications with breathing capacity.

BACKGROUND OF THE INVENTION Various types of polymeric films impervious to liquid and vapor permeable are known in the art. A method for making a vapor permeable polymer film involves mixing a polymer matrix with a substantial amount (eg, 10-70 percent by weight) of an organic or inorganic particulate filler such as, for example, calcium carbonate. , and extrude a film from the mix. The matrix polymer may include a polyolefin, such as polyethylene or polypropylene or various olefin copolymers. The film can be a monolayer film, a multi-layer film, which contains the filled layer as a primary layer together with skin layers with a thin breathing capacity, or a multi-layer film having more than one filled layer. Afterwards, the film is heated and stretched, causing gaps to form in the film.

Breathable films are employed as lower sheets, or as a lower sheet component laminated to a nonwoven fabric and / or other layers, in many of the current personal care absorbent articles, diapers being an example. Filled and filled polyolefin films provide good water vapor transmission, making diapers more comfortable for the user. As a result of this, the relative humidity and temperature within the diaper or other product can be reduced by using films and laminates with a capacity to breathe. - - - - _ - - - - - A disadvantage of the - Polyolefin films and laminates filled and voids are that they transmit ammonia and other vapors that cause odor as well as water vapor. For example, ammonia is the primary odor causing ingredient in urine. Also, films and polyolefin laminates with voids are generally non-elastic to a significant extent. Also, any particle agglomerates in the film before stretching can produce large pores which will drain. The fluids that wet such films (alcohols, water with surfactants, etc.) will pass through the holes. Bacteria and viruses can pass through the holes too. Also the gaps generated during stretching weaken the film.

SYNTHESIS OF THE INVENTION The present invention is directed to a breathable elastic film and a laminate useful as an outer cover for diapers and other personal care products, and surgical suits, which have a high permeability to water vapor and a low permeability to ammonia and some other molecules that cause odor. The film is formed of an elastic polymeric material in which the water molecules can be dissolved. Instead of resting on the molecular diffusion of water vapor through. holes or pores in the film, the films of the invention rest on the solubility of the water molecules, on the film - of solid polymer, the diffusion of the water molecules through the solid polymer film and on the evaporation of the water that passes through the film to the surrounding air. The water vapor molecules are absorbed into the film from one surface, pass through the film in an absorbed state, and are released from the other surface.

Elastic films do not absorb ammonia to any appreciable extent, and are not microporous or hollowed out.

Therefore, ammonia is not transmitted through the films in any significant extent, and ammonia odors are contained.

The film can be formed from any suitable elastic film-forming polymer that exhibits an ability to absorb and diffuse water vapor. Suitable polymers include without limitation the vulcanized silicone rubber, other silicone polymers, polyurethanes, polyether esters, and polyether amides.

The laminate of the invention includes at least one layer of breathable elastic film and a stretchable nonwoven fabric such as a narrowed nonwoven fabric. The woven fabric is preferably a spunbonded web, or a laminate which includes a spunbonded web. The film and the non-woven fabric are joined together, either thermally, ultrasonically, or with an adhesive, when the fabric is in an elongated "narrowed" condition. The attachment of the unstretched elastic film to the narrowed nonwoven fabric provides a breathable laminate which is stretchable in a direction parallel to the narrowing direction of the fabric prior to lamination, and which is partially or fully recovered when the stretching force is removed.

With the foregoing in mind it is a feature and advantage of the invention to provide a breathable laminate having improved elastic properties.

It is also a feature and advantage of the invention to provide a breathable laminate that is resistant to the penetration of the ammonia odor.

It is also a feature and an advantage of the invention to provide an improved breathable laminate useful in a wide variety of outer diaper covers, other personal care products, surgical suits, and other breathable applications.

The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of currently preferred embodiments, read in conjunction with the examples and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of an exemplary process for forming a composite elastic bonded-stretched material.

Figure 2 is a plan view of an exemplary constrictive material before tensioning and tapering.

Figure 2A is a plan view of an exemplary tapered material.

Figure 2B is a plan view of an elastic compound-bonded composite material as an example while being partially stretched in the transverse direction to the machine.

Figure 3 is a schematic representation of an example process for forming a bonded-tapered material elastic composite using a tensioned winding method.

Figure 4 is a representation of an exemplary joining pattern used to join layers of a compressed-elastic-bonded material. "r _: - - -, ~ _'_ .- -; - - ~. ~" ~ - -.

L5 Figure 5 shows the relationship between vapor permeability and thickness for films made of vulcanized silicone rubber.

Figure 6 shows a delta point-engraving model.

DEFINITIONS The term "elastic" is used herein to mean any material which, with the application of a pressing force, is stretchable, that is, can be lengthened, a pressed and stretched length which is at least about 160 percent of its relaxed unpressured length, and which, will recover at least 55 percent of s elongation with the release of the stretching elongation force. A hypothetical example would be a sample of one (1) inch of a material which is stretchable to at least 1.60 inches and which, when lengthened to 1.60 inches, will be recovered to a length of no more than 1.27 inches. . Many elastic materials can be stretched by much more than 60 percent of their relaxed length, for example 100 percent or more, and many of these will recover to essentially their original relaxed length, for example, to within 105: psr "; 100% of its original related length, - with the release of the stretching force - - - -, .-. - _.

As used herein, the term "breathability" refers to a film or laminate having a wet vapor transmission rate (MVTR) of at least about 300 grams / square meter-24 hours measured using the standard ASTM E96-80, vertical cup method, with minor variations as described in the test procedure given below.

As used herein, the term "non-elastic" refers to any material which does not fall within the definition of "elastic", given above.

As used herein, the term "recover" refers to a contraction of a stretched material upon the termination of a pressing force after stretching of the material by application of the pressing force. For example, if a material having a relaxed and unpressed length of one (1) inch is stretched 50 percent by stretching to a length of one and a half (1.5) inches, the material would stretch 50 percent (0.5 inches) and it would have a stretched length that is 150 percent of its relaxed length. If this stretched example material were to contract, this will be recovered to a length of one and one tenth (1.1) inches after the release of the pressing and stretching force. the material would have recovered 80- or hundred-. { 0.4 inches) of. your average (0.5) inch-of. elongation. The recovery can be expressed as [(length stretched maximum-length final sample) / (stretched length maximum-length initial sample)] X 100.

As used herein, the term "non-woven fabric" means a fabric or fabric having a structure of individual fibers or threads which are interleaved, but in a repetitive and identifiable manner. Non-woven fabrics have, in the past, been formed by a variety of tai processes, such as, for example, meltblowing processes, spinning processes, and knitting processes.

As used herein, the term "microfibers" means small diameter fibers having an average diameter of no more than about 100 microns, for example having a diameter of from about 0.5 microns to about 50 microns, more particularly, microfibers can It has an average diameter of around 4 microns to around 40 microns.

As used herein, the term "co-melt blown fibers" means fibers formed by extruding a thermoplastic-melted material through a plurality of matrix capillary cups, usually capillaries and fines such as filaments melted on the inside " A stream of gas at high speed (for example air) which attenuates the filaments of thermoplastic material to reduce its diameter, which can be a microfiber diameter, and then the fibers of blown with fusion are carried by the current of High-velocity gas is deposited on a collecting surface to form a fabric of meltblown fibers randomly disbursed.This process is described, for example, in US Pat. No. 3,849,241 issued to Butin, whose description is incorporated herein by reference.

As used herein, the term "spunbond fibers" refers to fibers of small diameter which are formed by extruding a melted thermoplastic material as filaments of a plurality of capillary and fine vessels of a spinning organ with the diameter of the fibers. extruded filaments then being rapidly reduced as by means of an eductive pull, for example, or other well known splicing mechanisms. The production of spunbonded nonwoven fabrics is illustrated in the patents such as, for example, in U.S. Patent No. 4,340,563 issued to Appel et al., And in the United States of America patent. No. 3,692,618 issued to Dorschner et al. The descriptions of both of these patents are incorporated herein by reference t ~ -. - .-- .. "- -.--- -: - z:. - - - t, - = -. • .-: - •: -; .- -. "-. - - - -. -. V .." "" -. - -, - - - - - Co - or - use - here, ... the - term - "interfiber union" means the union produced by the entanglement between the individual fibers to form a structure of coherent fabric without the use of thermal bonding This fiber entanglement is inherent in the meltblowing process but may be generated or augmented by such processes as, for example, hydraulic entanglement or bolt-hole drilling, alternatively and / or additionally, A binding agent can be used to increase the desired bond and to maintain the structural coherence of a fibrous web, For example, powdered bonding agents and chemical solvent bonding can be used.

As used herein, the term "sheet" means a layer which can be either a film or a non-woven fabric.

As used herein, the term "tapered material" refers to any material which has been narrowed in at least one dimension by the application of a tensioning force in another direction.

As used herein, the term "constrictive material" means any material that can be constricted.

As used herein, the term "constriction percent" refers to the ratio determined by measuring the difference between the non-constricted dimension I and the constricted dimension of the constrictable material and then dividing the difference by the non-constricted dimension of the material Narrowable As used herein, the term "composite elastic bonded-stretched material" refers to a material having an elastic sheet attached to a material tapered in at least two places. The elastic sheet can be joined to the material narrowed in intermittent points or it can be completely joined to it. The bonding is achieved while the elastic sheet and the tapered material are in a juxtaposed configuration. The composite elastic-bonded material is elastic in a direction generally parallel to the narrowing direction of the constricted material A composite elastic-bonded composite material may include more than two layers For example, the elastic sheet may have a narrowed material attached on both sides so that an elastic bonded material composed of three layers is formed having a structure: narrowed material / elastic sheet / narrowed material, both narrowed materials being elongated in the same direction Elastic sheets and / or elastic sheets may be added. Additional narrow material layers Even other combinations of elastic sheets and narrowed materials can be used.

As •;•; se- -_-_ usa :: a-q ír, ~ ..the term. - "palindromic laminate" means-, un-; laminate. , -. multiple layers > For example, a narrowed-bonded elastic composite material which is essentially symmetrical. The example palindridic laminates will have layer configurations of A / B / A, A / B / B / A, A / A / B / B / A / A, etc. Examples of non-palindromic laminates will have layer configurations of A / B / C, A / B / C / A, A / C / B / D, etc.

As used herein, the term "polymer generally includes but is not limited to homopolymers, copolymers, such as, for example, blog, graft, random and alternating copolymers, terpolymers, etc. and mixtures thereof. and, unless specifically limited otherwise, the term "polymer" will include all possible geometric configurations of the material.These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.

As used herein, the term "water vapor permeable elastic polymer" refers to an elastic polymer whose films have a water permeability of at least about 150 kilogram-centimeters / (km) 2-day at 38 degrees centigrade and 100 percent relative humidity, measured according to ASTM E-96-80, inverted cup method. Further discussion of permeability is provided in the Kirk-Othmer Chemical Technology Encyclopedia, third edition, volume "3 of John iley ~" & "Sons, pages" 486-4-96, whose description. is incorporated - here by "-reference ... a: As used herein, the term "consisting essentially of" does not exclude the presence of additional materials which do not significantly affect the desired characteristics of a given composition or product. Exemplary materials of this class will include, without limitation, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solvents, particulates and aggregate materials to improve the processability of the composition.

TEST PROCEDURE FOR MEASUREMENT OF TRANSMISSION RATE OF HUMIDITY VAPOR (MVTR) A measurement of the breathability of a fabric is the moisture vapor transmission rate (MVTR), which for the sample materials was calculated essentially in accordance with ASTM E-96-80 with small variations in the procedure test as stated below. Circular samples measuring three inches in diameter were cut from each of the test materials, and tested together with a control which is a piece of CELGARD® 2500 sheet from Celanse Separation Products of Charlotte, North Carolina. The sheet CELGARD® 2500 is a microporous polypropylene sheet. Three samples were prepared for each material. The test dish is a tray of Vapometer number 60-1 distributed by Thwing-Albert Instruments Company of Philadelphia, Pennsylvania. One hundred milliliters of water was poured into each Vapometer tray and the individual samples of the test materials and control material were placed through the open top portions of the individual trays. The bolted flanges are tightened to form a seal along the edges of the tray, leaving the associated test material or control material exposed to the ambient atmosphere over a circle of 6.5 centimeters in diameter with an exposed area of approximately 33.17. square centimeters. The trays are placed in a forced air oven at 100 degrees F (32 degrees Celsius) for one hour to balance. The oven is a constant temperature horn with external air circulating through d this to prevent water vapor from accumulating inside. A suitable forced air furnace is, for example, a Blue Power-O-Matic 60 furnace distributed by Blue M Electric Company of Blu Island, Illinois. When the balance is complete, the trays are removed from the oven, weighed and immediately returned to the oven. After 24 hours, the trays are removed from the horn and weighed again. The values of water vapor transmission rate of preliminary test were calculated as follows: MVTR test - (weight loss grams over 24 hours) x 315.5 g / m2-24 hours.

The relative humidity-, inside - -.- of the furnace is not specifically controlled .. r ~ - -. ,. 7 - Under predetermined set conditions of 100 degrees F (32 degrees Celsius) and relative humidity to the environment, the moisture vapor transmission rate for the CELGAR® 2500 control has been defined as being 5,000 grams per square meter per 24 hours. Therefore, the control sample was run with each test and the preliminary test values were corrected to set conditions using the following equation: MVTR = (MVTR test / MVTR control) x (5000 g / m2-24 hours).

DETAILED DESCRIPTION OF CURRENTLY PREFERRED INCORPORATIONS Referring to Figure 1 of the drawings there is schematically illustrated in point 10 a process for forming a composite stretch-bonded stretch-bonded laminate material. A constrictable material 12 is unwound from the supply roll 14 and moves in the direction indicated by the arrow associated therewith as the supply roll 14 rotates in the direction of the arrows associated therewith. The narrowable material 12 passes through a pressure point 16 of the drive roller arrangement 18 formed by the drive rollers 20 and 22.

The narrowable mateirial 12 can be formed through known spin-bonding processes, and passed directly through the pressure point 16 without first being stored on a supply roll.

A breathable elastic sheet 32 including a water vapor soluble polymer is unwound from a supply roll 34 and is moved in the direction indicated by the arrow associated therewith as the supply roll 34 is rotated in the direction of the rolls. arrows associated with it. The elastic sheet passes through the pressure point 24 of the joining roller arrangement 26 formed by the joining rollers 28 and 30. The elastic sheet 32 can be formed through extrusion processes such as, for example, the processes of film extrusion. and passing directly through the pressure point 24 without first being stored on a supply roll.

The breathable elastic sheet made of the water vapor permeable polymer must have a moisture vapor transmission rate (MVTR) of at least about 30 grams / square meter / 24 hours, preferably at least about 1,200 grams / square meter / 24 hours, more preferably at least about 2 grams / square meter / 24 hours. The moisture vapor transmission rate is a function of both the film thickness and the type of polymer. Preferred elastic polymers which exhibit the moisture vapor transmission rate required over a range of useful film thicknesses include whether to limit the vulcanized silicone rubber, some other silicone polymers, polyurethanes, polyether esters, polyether amides. The following Table 1 gives water vapor permeabilities representative of the elastic polymers d example.

B If the elastic polymer has a low water vapor permeability, the film may have to be extremely thin in order to achieve the minimum level of moisture vapor transmission rate. The production and use of very thin films can be impractical due to processing difficulties and low film resistance. The elastic polymer itself must therefore have a sufficient water vapor permeability to allow the use of films having practical thicknesses. Preferably, the elastic polymer will have a water vapor permeability of at least about 150 kg-cm / (kilometer) 2-day, more preferably at least about 500 kg-cm / (km) 2- day, more preferably of at least about 1,000 kg-cm / (km) 2-day.

In addition to being permeable to water vapor, the elastic film capable of breathing must not be thick enough to essentially prevent its transmission from the water vapor. The moisture vapor transmission rate of a particular film composition is approximately inversely related to its thickness if there are no molecular interactions between the film and the vapor. For water vapor permeable films, this relationship can vary due to the affinity of the water with the films. Figure 5 shows the relationship between the logarithm of film thickness (mils) and e logarithm of moisture vapor transmission rate, MVT (grams / m2-24 hours), for films made of vulcanized silicone rubber. The moisture vapor transmission rate was tested using the standard .ASTM E-96-80y- 'cup-vetttica-1' method, -co minor variations- is described in the above mentioned "procedure" Using the linear regression techniques on the six data points shown, it was found that the moisture vapor transmission rate is related to the film thickness as follows: MVTR (g / m2-24 hours) = 4700 x (thickness, mils) -1.3 Therefore, a two-mil thick film of vulcanized silicone rubber should have a moisture vapor transmission rate of about 2,000 grams / square meter-24 hours. Generally, the film thickness for which "elastic water vapor permeable polymer" must be selected to give a moisture vapor transmission rate of at least about 300 grams / square meter-24 hours, preferably at least about of 1,200 grams / square meter-24 hours, more preferably at least about 2,000 grams / square meter-24 hours when the film is in a stretched state. The elastic polymers having somewhat less water vapor permeability than the vulcanized silicone hul should therefore be made into thinner films in order to achieve comparable vapor transmission. For example, the elastic stretched vapor permeable film may be less than about one thousand thick, or less than about 0.5 mil thick or less than about 0.3 mil thick depending on the strength of the film and d the water permeability of the polymer water. -to The elastic water vapor permeable polymer films can be degraded or thermoplastic, depending on the polymer. The vulcanized silicone rubber is preferably degraded to provide sufficient film strength. Degradation can be achieved by applying heat treatment such as by placing the films in an oven. The polyurethanes can be thermoplastic or degraded. Polyether esters and polyether amides are generally thermoplastic.

In a preferred embodiment, the elastic film can be etched to further increase its moisture vapor transmission rate. Any polymer that can be made in an elastic film, recorded, and which retains at least some of the engraved model will exhibit this improvement. Some polymers, such as silicone rubber, can be degraded to fix the etched model. A suitable etching model is a "delta point" model shown in Figure 6, which is a model of solid diamonds or squares printed on a film using a conventional etching technique. A film recorded with a delta-point model is thinner in the "windows" defined by the printed squares, than in the "frames" or non-engraved regions surrounding the windows. If the transmission rate of "steam: of ~ moisture" and "is related to the thickness," or related "of" agreed "to the" equation • given above, then the engraving - serves to increase the moisture vapor transmission rate in the "window" regions printed against the non-engraved regions, and effectively increases the overall moisture vapor transmission rate for the movie.

Figure 5 shows the moisture vapor transmission rate for a recorded film sample of vulcanized silicone rubber having a thickness of 19 mils in the frame regions, a thickness of only 3.2 mils in the window regions caused by the model delta point engraving, and a general thickness (average) of around 16 mils. This film sample designated with an asterisk (*) in Figure 5. The moisture vapor transmission rate for the recorded film sample is substantially higher than for a vulcanized silicone rubber film having the same overall thickness as indicated by the position of the asterisk essentially above the line.

The woven component bonded with yarn from the laminate is typically open and porous, and does not significantly affect the breathability of the laminate. In other words, the ability to breathe moisture from the film must determine the ability to breathe from the laminate. However, care must be taken to bond the film and the fabric together using techniques that do not significantly disrupt the ability of the laminate to breathe. If an adhesive is used, the adhesive should cover only a part of the total film area, and should be applied as thin as possible. The preferred adhesive for bonding the polyurethane or polyether ester films to a spunbonded web is a reactive polyurethane based adhesive available from Shawmut Mills in Bridgewater, Massachusetts. When used, an adhesive should be applied to a basis weight of less than about 5.0 grams per square meter (gsm), preferably less than about 1.0 grams per square meter, more preferably less than about 0.5 grams per square meter. The adhesive should preferably cover no more than about 75 percent of the film surface unless the adhesive itself is very permeable to water.

When thermal bonding is employed, the bonding conditions must be such that the spunbond fabric is not unnecessarily compressed or fuses together, and the film is not damaged or distorted in a manner that significantly impairs the ability to breathe moisture. . The thermal calendering joint is a preferred technique, using a spaced and spaced joint pattern that joins the fabric and the film together at less than about 25 percent of the total interfacial area, preferably less than about 20 percent of the total interfacial area, more preferably less than about 15 percent "of the area - interf-aci-al total.-" - - _ - - - _ _ In -the process -showed in Figure 1, the web-bonded fabric 12 passes through the melting point 16 of an S-roll arrangement 18 in an inverse S-path as indicated by the rotation direction arrows associated with the rollers. of stack 20 and 22. From the roller arrangement at S 18, the narrowable fabric 12 passes through the pressure point 24 formed by a binding roller arrangement 26. Because the peripheral linear speed of the rolls of the roller arrangement in S 18 is controlled to be less than the peripheral linear speed of the rollers of the binding roller arrangement 26, the narrowable fabric 12 is tensioned between the roller arrangement S 18 and the pressure point of the binding roller arrangement 26. By adjusting the difference of the In the case of the rollers, the stretchable fabric 12 is tensioned so that it narrows or narrows by a desired amount and remains in such a tight and stressed condition while the breathable elastic sheet 32 is attached to the narrowed fabric 12. during its passage through the binding roller arrangement 26 to form a composite elastic bonded-bonded laminate 40.

Other methods of tensioning the constrictable fabric 12 can be used such as, for example, the tenter frames or other stretcher arrangements in the transverse direction to the machine that expand the narrowable fabric 12 in other directions, such as, for example, . direction transversally to the machine, so that, after joining the elastic sheet with a capacity for breathing 32, the resulting composite elastic-bonded material 40 will be elastic in a direction generally parallel to the narrowing direction, for example, in the address of the machine.

The narrowable fabric 12 may be a porous nonwoven material such as, for example, a spunbonded fabric, a meltblown or a bonded and carded fabric. If the shrinkable material is a meltblown fiber fabric, this may include meltblown microfibers. The narrowable material 12 can be made of fiber-forming polymers such as, for example, polyolefins. Exemplary polyolefins include one or more of polyethylene, polypropylene, ethylene copolymers, propylene copolymers, and butene copolymers. Useful polypropylenes include, for example, the polypropylene available from Exxon Chemical Company under the trade designation Exxon 3445, and the polypropylene available from Shell Chemical Company under the trade designation DX 5A09.

In one embodiment of the present invention, the narrowable fabric 12 is a multilayer material having, for example, at least one layer of a spunbonded fabric attached to at least one layer of: - Stroked, with fusion, a carded fabric and an other suitable material. For example, "the narrowable material: 12 can be u-material ... of multiple layers having a first layer of polypropylene joined with spinning having a basis weight of from about 0.2 to about 8 ounces per square yard ( osy), a melt blown polypropylene layer having a basis weight of from about 0.2 to about 4 ounces per square yard, and a second layer of a spin-linked polypropylene having a basis weight of from about 0.2 to about 8 ounces per square yard Alternatively, the narrowable fabric 12 can be a single layer of material such as, for example, a spunbond fabric having a basis weight of from about 0.2 to about 10 ounces per square yard or a blown fabric with fusion having a basis weight of from about 0.2 to about 8 ounces per square yard.

The narrowable material 12 may also be a composite material made of a mixture of two or more different fibers or a mixture of fibers and particulates. Such mixtures can be formed by adding fibers and / or particles to the gas stream in which the meltblown fibers are carried so that intimate entanglement of the melt blown fibers and other materials occurs, for example. , wood pulp, short and particulate fibers such as, for example, the hydrocolloid particulates (hydrogel) commonly referred to as super absorbent materials - prior to the collection of the fibers -solated with fusion on a collecting device: to form a coherent fabric of randomly dispersed meltblown fibers and other materials as described in U.S. Patent No. 4,100,324, the disclosure of which is incorporated herein by reference.

If the constrictable fabric 12 is a non-woven fiber fabric, the fibers must be joined by a interfiber joint to form a coherent fabric structure which is capable of withstanding the constriction. The interfiber joint can be produced by the entanglement between the individual meltblown fibers. Fiber entanglement is inherent in meltblowing processes but can be generated or augmented by processes such as, for example, hydraulic entanglement or bolt drilling. Alternatively and / or additionally, a binding agent can be used to increase the desired bond.

The elastic sheet 32 may also be a multi-layer material in the sense that it may include two or more individual coherent films or films. Additionally, the elastic sheet 12 can be a multi-layer material in which one or more of the layers contains a mixture of elastic and non-elastic particulate fibers.

- • The -.- arrangement-die.- "uniting roller" 26 can include a calendering roller: - with "-pattern," -such as, for example, u engraving roller "with:. With one or both smooth rollers, one or both of the calender roller and the smooth roller can be heated and the pressure between these rolls can be adjusted through well-known means to provide the desired temperature, if any, and the joint pressure to join the narrowed material 12 to the elastic sheet 32 forms a narrowed-bonded elastic material with a composite breathing capability 40.

The tapered material and the elastic sheet can be completely bonded together and still provide a composite elastic-bonded composite material with good stretch properties. That is, a composite elastic material can be formed by attaching a constricted material to an elastic sheet using bonding surfaces such as, for example, the sinusoidal bonding pattern shown in Figure 4. The pattern has approximately 75 bolts per square inch with each bolt about 0.059 inches in diameter, providing a combined surface area of about 20.5 percent.

The narrowed materials can be attached to the resilient elastic sheet 32 in at least two places by suitable means, such as, for example, thermal or adhesive bonding or ultrasonic welding which smoothes at least parts of the sleeve. - less-one: of the materials, usually the elastic sheet because the elastomeric materials used to form the elastic sheet 32 have a low softening point than that of the narrowed material components. The joint can be produced by applying heat and / or pressure to the elastic sheet on laying 32 and the narrowed material 12 by heating these parts (or of the layer on lay) to at least the softening temperature of the material with the softening temperature lower to form a joint. reasonably strong and permanent between the resolidified smoothed portions of the elastic sheet 32 and the narrowable material 12. The conditions should not be so severe as to perforate the film.

The elastic sheets can be used having basis weights of less than 0.5 ounces per square yard, for example from about 0.25 to about 0.4 ounces per square yard. Such extremely low basis weight sheets are advantageous for economic reasons and a superior ability to breathe, and are particularly useful in disposable products. Additionally, the elastic sheets may also be used having higher base weights such as, for example, from about 0.5 to about 10 ounces per square yard.

With regard to thermal bonding, a person skilled in the art will appreciate that the temperature at which the materials, or at least the bonding sites thereof, are heated for bonding-with heat will depend not only on the temperature of the materials. heated rollers or other sources, de-calo-r ^ si_np ^ deli.times of permanence of the materials on the heated surfaces, the base weights of the materials and their specific heats and thermal conductivities. However, for a given combination of materials, and in view of the description contained in which "the processing conditions necessary to achieve a satisfactory bond can be readily determined by one skilled in the art.

Conventional drive means and any other conventional devices that may be used in conjunction with the apparatus of Figure 1 are known and for the purposes of clarity are not illustrated in the schematic view of Figure 1.

The relationship between the original dimensions and the narrowing material 12 to its dimensions after tensioning determines the approximate limits of stretching of the composite elastic-bonded material. Because the narrowable material 12 is capable of stretching and returning to its narrowed dimensions in directions such as, for example, machine direction or cross-machine direction, the composite elastic-bonded material will be stretched generally in the same direction. direction that the material narrow 12.

For example, with reference to Figures 2, 2A 2B, if it is desired to prepare a stretchable compound elastic-bonded composite material at an elongation of 150 percent, a width of the narrowable material shown schematically and not necessarily to scale in Figure 2 having A width "A" such as, for example, 250 centimeters, is tensioned so that it narrows down to a width "B" of about 10 centimeters. The narrowable material shown in Figure 2A and then attached to an elastic sheet (not shown) having a width of approximately 100 centimeters and which is at least stretchable to a width of 250 centimeters. The resulting composite elastic-bonded composite shown schematically and not necessarily to scale in Figure 2B has a width "B" of about 100 centimeters and is stretchable to at least the original width "A" of 250 centimeters of the narrowable material for an elongation of around 150 percent. As can be seen from the example, the elastic limit of the elastic sheet requires only to be as large as the desired elastic limit itself of the composite elastic bonded-bonded material.

Referring now to Figure 3 of the drawings, there is illustrated schematically with the number 50 an example process for forming a stretched-bonded elastic composite material through "rolled and tensioned method". A first narrowable material 52 is unwound from a supply roll 54 and a second narrowable material 82 is unwound from a supply roll 84. The narrowable materials 52 and 82 then move in the direction indicated by the arrows associated therewith when turning the supply rolls 54 and 84 in the direction of the arrows associated therewith. The narrowable material 52 then passes through the pressure point 56 of an S-roll arrangement 58 formed by the pile rollers 60 and 62. Similarly, the narrowable material 82 passes through the pressure point 86 of an arrangement S-roll 88 formed by "stack rollers 90 and 92. Narrowable materials 52 and 82 can be formed by known non-woven extrusion processes such as, for example, known spinning bonding processes and / or blown with known melt and are passed through pressure points 56 and 86 without first being stored on the supply rolls.

An elastic sheet 72 is unwound from a supply roll 74 and moves in the direction indicated by the arrow associated therewith as a supply roll 74 is rotated in the direction of the arrows associated therewith. The elastic sheet 72 can be formed by means of an extrusion process such as, for example, extrusion processes of blown film or set film without first being stored on "a" delivery roll. - - - •• - •• ---- ------- - • ... .. ... . ... The shrinkable material 52 then passes through a pressure point 56 of an S-roll arrangement 58 on a reverse S-wrapper path as indicated by the direction of rotation of the arrows associated with the stack rollers 60 and 62. Similarly, the narrowable material 82 passes through a pressure point 86 of an S-roll arrangement 88 in an inverted S-wrapper path as indicated by the direction arrows of rotation associated with the stack rollers 90 and 92. Because the peripheral linear speeds of the rollers of the roller arrays at S 58 and 88 are controlled to be lower than the peripheral linear speed of the rollers of the wound roller 94, the narrowable materials 52 and 82 are constricted and tensioned so that they take on the sandwich shape the elastic sheet 72 as it rolls over the winding roll 94.

The tensioned winding joining methods described above are suitable for low base weight elastomeric sheets. For example, elastic sheets can be used having basis weights less than 0.5 osy (ounces per square yard), for example, from about 0.25 to about 0.4 ounces per square yard. Such extremely low basis weight sheets are useful for economic reasons, particularly in disposable products. Additionally, elastic sheets having higher basis weights such as, for example, from about 0.5 to about 10 ounces per square yard can also be used. The elastic sheet can also be extruded onto the narrowed non-woven fabric.

With regard to the joint pressure used when the joint is made by the tensioned winding method described above, the specification of a joint pressure does not take into account in itself the complicating factors such as, for example, the joint compatibility of the elastic sheet and the narrowed materials and / or the base weight weights of the materials. Notwithstanding this, one skilled in the art, taking into consideration such factors will be able to appropriately select an effective joint pressure and to vary it.

The conventional drive means and other conventional devices which can be used in conjunction with the apparatus of Figure 3 are well known and, for the purposes of clarity, have not been illustrated in the schematic view of Figure 3.

In one embodiment, the stretchable elastic film 32 may be pre-joined to another elastic layer unible before being laminated to the narrowable fabric 12. For example, the stretch film 12 may be a thin layer of a polyether ester sold under the trade name Hytrel , by DuPont Company, located in "Delawaréd Cá film 12 can be combined with a meltblowing layer made by Kimberly-Clark Corporation of another polyether ester sold under the trade name Arnitel, by DSM Company of Evansville, Indiana. it gives excellent water vapor permeability The meltblown fabric should have a basis weight of about 10-75 grams per square meter, preferably about 15-50 grams per square meter, more preferably about 20- 40 grams per square meter Preferably, the meltblown filaments are about 10-30 microns in diameter The meltblown film and fabric combined they can be laminated to a fabric bonded with tapered yarn to provide a laminate having excellent water vapor permeability and an ammonia odor barrier, a high hydro head, a directional elasticity, and a smooth feel.

The fabric blown with polyether ester adds considerable strength to the film 12 without impairing its ability to breathe. The film 12 can be joined to the meltblown fabric using a bonding technique, for example, a bonding process of adhesive printing known to those of skill in the art. The final laminate may have the configuration of fabric bonded with narrow yarn / elastic film / blown fabric with elastic fusion or may have the configuration of a fabric bonded with narrow yarn / blown cloth with elastic melting / elastic film. Also, as long as the meltblown fabric is porous, it does not need to include a water soluble polymer, but it can be of any elastic polymer, for example styrene-butadiene rubbers of the Kraton brand.

In another embodiment of the invention, the elastic breathable film or laminate may be stretched in a direction other than parallel (e.g. perpendicular) the narrowing direction of the non-woven fabric, and laminated to the fabric in a plurality of spaced apart locations. while it is in the stretched condition and while the fabric is narrowed. After the lamination, the elastic or laminated film relaxes, causing the fabric to gather or fold between the joined regions. The resulting composite laminate is stretchable in at least two non-parallel directions. The stretching of the composite in the directions parallel to the direction of narrowing is facilitated by the constriction of the fabric. The stretchability of the composite in the non-parallel direction (for example perpendicular) to the direction of narrowing is facilitated by the gathering of the fabric in that direction. The processes for manufacturing a multidirectional stretch laminate of an elastic film and a narrow nonwoven fabric are described in U.S. Patent Nos. 5,116,662 and 5,114,781, both issued to Morman, the disclosures of which are incorporated herein by reference. reference.

Using a non-woven non-woven fabric for the process described above will produce a laminate that is stretched only in the direction in which the elastic sheet was stretched before joining. Such a process, and a resulting laminate, are described in U.S. Patent No. 4,720,415 issued to Vanderielen et al.

Other layer combinations are also possible for the breathable elastic laminate of the invention. Regardless of the configuration and number of layers, the breathable elastic laminate must include at least one breathable elastic film and at least one narrow non-woven layer (preferably spun-bonded). Additives such as odor absorbing chemicals (for example, ammonia-absorbing chemicals) can also be included in the laminate. Such additives can be added as particles during the formation of the elastic film through the setting extrusion, for example. The additives can be included in an amount of up to 80 percent by weight of the film, preferably around 20-60 percent by weight of the film. Useful odor absorbing additives include zeolites, other absorbent additives and combinations thereof.

EXAMPLE . 1 One piece of unvulcanized Silastic® silicone rubber sheet from Dow Corning Corporation of Midland, Michigan was etched with a large delta dot pattern. The delta points (window) covered 16 percent of the total film area, while the non-recorded regions (picture) between the points covered 84 percent of the total film area. The film was vulcanized in a heated oven to fix the engraved model. The vulcanized film had a thickness of 19 mils in the box areas, 3.2 mils in the window areas, 16.1 mils as a heavy average.

The moisture vapor transmission rate of the film was measured using ASTM E 96-80 (vertical cup method), modified slightly as described above, and found to be 249 grams / square meter-24 hours. A flat film of the same thickness (16.1 mils) would be expected to give a moisture vapor transmission rate of 127 grams / square meter-24 hours, calculated from the equation derived from the data in Figure 5 and stated below: Humidity Vapor Transmission Rate = 4,700 x (thickness, mils) "13 From the same equation, it can be expected that a completely flat film "would have to" have a thickness of only 9.6 mils in order to have a moisture vapor transmission rate of 249 grams / square meter-24 hours. By recording the film, a moisture vapor transmission rate typical of much thinner films can be achieved.

Notably, the moisture vapor transmission rate of the recorded film can be predicted from the same equation, by treating the recorded and non-recorded regions as separate areas in proportion to the total area.

Predicted MVTR = .84 (4700) (19) "13+ .16 (4700) (3.2)" 13 = .84 (102) + .16 (1036) = 86 + 165 = 251 grams / m2-24 hours The predicted moisture vapor transmission rate of 251 grams / square meter-24 hours is essentially the same as the measured moisture vapor transmission rate of 249 grams / square meter-24 hours. From the equation, it can be seen that about two-thirds of the vapor transmission passes through the window regions, even though they constitute only 16 percent of the total film area.

EXAMPLE - A - film -Hytrel® 8171 (pslieter ester) having a non-stretched thickness of 1 mil was adhesively laminated to a non-woven blowing fabric (polyether ester) Arnitel® using a reactive polyurethane adhesive. This laminate was then bonded to a polypropylene material bonded with reversibly tapered yarn using a patented spray adhesive sold by 3M Corporation under the trade name Super 77®. The reversibly narrowed materials are described in the United States patents of North America numbers 4,981,747 and 4,965,122, both issued to Morman, whose descriptions of which are incorporated herein by reference. The fabric used has a starting basis weight of 0.8 ounces per square yard and narrowed from a width of 17.75 inches to a width of 8.5 inches, and settled with heat in the constricted condition. The resulting three-layer laminate had a smooth outer coating of the layer bonded with narrow yarn, good elastic properties of the polyether ester film and the meltblowing layer, good total film barrier properties (evidenced by a hydro head exceeding 120 centimeters, measured using 7AATCC 127-89) of the polyether ester film, and an excellent water vapor transmission (evidenced by a moisture vapor transmission rate of 3200 grams / square meter-24 hours) due to the structures of bonding with spinning and blowing with fusion and to the high permeability of the moisture of the polyether ester constituting the film. The moisture vapor transmission rate was measured using ASTM-E 96-80 (vertical cup method), modified slightly as described above.

E E M P O This example was carried out to test the ammonia odor barrier for an elastic polyurethane film capable of breathing against a microporous breathable film of the prior art. Two of the test dishes (cups) typically used to measure the moisture vapor transmission rate (described in the test procedure mentioned above) were each partially filled with about 50 cc of a commercially identified ammonia-based cleaner. as "Cleaner for All Purposes of Fresh Lemon Ammonia". A sample of a microporous polyolefin film PL-1845-based Dow Affinity® 1 mils thick was placed on a cup and sealed. Dow Affinity® PL-1845 is a linear low density polyethylene catalyzed by metallocene (LLDPE). The LLDPE was made microporous by combining the resin with more than 50 weight percent of a calcium carbonate filler, mixing with melted the two components, extruding a film from the mixture and stretching the extruded film in one direction. A sample of 1-mil thick breathable elastomeric polyurethane film was placed on the other cup and sealed. The microporous LLDPE-based film had a moisture vapor transmission rate of around 4,000 grams / square meter-24 hours. - The elastomeric polyurethane had a moisture vapor transmission rate of about 1,800 grams / square meter. 24 hours.

Three people were asked to smell each sealed cup. All three people were able to smell the ammonia very strongly from the cup covered with the LLDPE-based film. All three people were able to detect only a light lemon scent from the cup covered with the polyurethane film. This result suggests that the polyurethane allows the passage of water vapor and lemon perfume but not ammonia, and provides a barrier to ammonia that does not exist in the microporous filled LLDPE film.

Although the above described modalities are considered currently preferred, various modifications and improvements can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated by the appended claims and all changes that fall within the meaning and range of equivalence are intended to be encompassed here.

Claims (45)

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

1. An elastic laminate capable of breathing, comprising: an elastic film capable of breathing; a non-woven non-woven fabric bonded to the film while the non-woven fabric is tapered and the film is in an unstretched state; the laminate has a moisture vapor transmission rate of at least about 300 grams / square meter-24 hours.

2. The laminate as claimed in clause 1 characterized in that the film comprises a silicone polymer.

3. The laminate as claimed in clause 2 characterized in that the silicone polymer comprises vulcanized silicone rubber.

4. The laminate as claimed in clause 1 characterized in that the film comprises a polyurethane.

5. The laminate as claimed in clause 1 characterized in that the film comprises a polyether ester.

6. The laminate as claimed in clause 1 characterized in that the film comprises a polyether amide.

7. The laminate as claimed in clause 1 characterized in that the film comprises a polymer which has a water vapor permeability of at least about -ISO rkg-Centimeter / (kilometer) -day at 38 degrees centigrade and a relative humidity of 100 percent.

8. The laminate as claimed in clause 1 characterized in that the film comprises a polymer which has a water vapor permeability of at least about 500 kg-cm / (km) 2-day at 38 degrees centigrade and a relative humidity of 100 percent.

9. The laminate as claimed in clause 1 characterized in that the non-woven fabric comprises a spunbonded fabric.

10. The laminate as claimed in clause 1 characterized in that the fabric comprises a polymer which has water vapor permeability of at least about 1,000 kg-cm / (kilometer) square-day at 38 degrees centigrade and 100 percent relative humidity.

11. The laminate as claimed in clause 9 characterized in that the spunbonded fabric comprises polypropylene.

12. The laminate as claimed in clause 1 characterized in that it has a moisture vapor transmission rate of at least about 1,200 g / square meter-24 hours. .., m "-", _ _. ^ * - ... ^, _J,, .- - .. _ *

13. The laminate as claimed in clause 1 characterized in that it has a moisture vapor transmission rate of at least about 2,000 g / square meter-24 hours.

14. The laminate as claimed in clause 1, characterized in that it comprises a second non-woven fabric.

15. The laminate as claimed in clause 1 characterized in that the film is engraved.

16. The laminate as claimed in clause 1 characterized in that the film essentially blocks the passage of the ammonia odor.

17. An outer cover for diaper comprising the laminate as claimed in clause 1.

18. A surgical suit comprising the laminate as claimed in clause 1.

19 A breathable elastic laminate, comprising: • a water vapor permeable elastic "pellicle" comprising a polymer selected from the group consisting of silicone polymers, polyurethanes, polyether esters, polyether amide and combinations thereof; a fabric joined with narrowable yarn attached to the film; the laminate has a moisture vapor transmission rate of at least about 1,200 grams / square meter-24 hours.

The laminate as claimed in clause 19 characterized in that the polymer comprises vulcanized silicone rubber.

21. The laminate as claimed in clause 19 characterized in that the film has a thickness no greater than about 1.0 mil, in an unstretched condition.

22. The laminate as claimed in clause 19 characterized in that the film has a thickness no greater than about 0.5 mil, in an unstretched condition.

23. The laminate as claimed in clause 19 characterized in that the film has a thickness no greater than about 0.3 mil, in an unstretched condition.

24. The laminate as claimed in clause 19 characterized in that the film and the fabric are thermally bonded together.

25. The laminate as claimed in clause 19 characterized in that the film and the fabric are adhesively bonded together.

26. The laminate as claimed in clause 19 characterized in that the spunbonded web is tapered when the web is in an unstretched state.

27. The laminate as claimed in clause 19 characterized in that the film further comprises one or more odor absorbing chemicals.

28. The laminate as claimed in clause 27 characterized in that the one or more chemical odor absorbers comprise an ammonia-absorbing chemical.

29. The laminate as claimed in clause 19, characterized in that the film is engraved.

30. The laminate as claimed in clause 19, characterized in that it comprises an additional non-woven fabric.

31. The laminate as claimed in clause 19 characterized in that the film essentially blocks the passage of the ammonia odor.

32. An outer diaper cover comprising the laminate as claimed in clause 19.

33. A surgical suit comprising the laminate as claimed in clause 19.

34 An elastic laminate with breathing capacity, comprising: a breathable elastic film that has the first and second sides; a non-woven layer blown with fusion joined to the first side of the film; Y a non-woven layer bonded with yarn attached to the second side of the film.

35. The laminate as claimed in clause 34 characterized in that the film comprises a polyether ester. -

36. The laminate as claimed in clause 34, characterized in that the melt blown nonwoven layer comprises a polyether ester.

37. The laminate as claimed in clause 34 characterized in that the film and the meltblown nonwoven layer each comprise a polyether ester.

38. The laminate as claimed in clause 34, characterized in that the film and the non-woven layer blown with melting comprise two different polyether esters.

39. The laminate as claimed in clause 34 characterized in that the film is engraved.

40 A breathable elastic laminate, comprising: a breathable elastic film; Y a non-woven shrinkable laminate attached to the film; the laminate has a moisture vapor transmission rate of at least about. dOO grams / square meter-24 hours.

41. The breathable elastic laminate as claimed in clause 40, characterized in that the non-woven non-woven laminate comprises a film and a meltblown nonwoven fabric.

42. The breathable elastic laminate as claimed in clause 41 characterized in that the film comprises polyether ester.

43. The breathable elastic laminate as claimed in clause 41 characterized in that the melt blown fabric comprises polyether ester.

44 A breathable elastic laminate, comprising: an elastic film capable of breathing; Y a non-woven web that can be joined to the film; the non-woven fabric is tapered in a first direction when the film is in an unstretched state; ~ the film and the fabric are joined together while the film is stretched in a second direction not parallel to the first direction.

45. The breathable elastic laminate as claimed in clause 44 characterized in that the second direction is essentially perpendicular to the first direction. E S U M E N A breathable elastic laminate is formed by joining a film including a water soluble steam-soluble polymer to a non-woven web that can be narrowed so that when the film is relaxed, the fabric is in a narrowed state. The breathable laminate is stretchable in a direction parallel to the narrowing or narrowing of the fabric. The laminate has an excellent permeability to water vapor but acts as a barrier to the passage of the chemicals that cause the smell including ammonia.