KR20080036949A - Elastic nonwoven sheet for medical articles - Google Patents

Abstract

This invention relates to stretchable nonwoven sheets prepared by substantially uniformly impregnating a necked nonwoven substrate or an easily extensible as-made nonwoven substrate with an elastomeric polymer by treatment with an elastomeric polymer solution. The nonwoven sheet is useful in the manufacture of diapers and other hygiene articles. The nonwoven sheet is also useful in medical articles and applications.

Description

Elastic nonwoven sheet for medical products {ELASTIC NONWOVEN SHEET FOR MEDICAL ARTICLES}

Reference of related application

This application is part of a continued application of US Patent No. 10 / 413,172 filed April 14, 2003.

The present invention relates to stretchable nonwoven sheets suitable for use in the manufacture of medical or personal care products. More specifically, the stretchable nonwoven sheet is formed by substantially uniformly impregnating the elastomeric polymer in a necked nonwoven substrate or an easily extensible nonwoven substrate.

Elastic nonwoven materials are well known in the art. Examples of elastic nonwoven materials are "stretch-bonded" and "neck-bonded" laminates. Stretch-bonded laminates are made by bonding a gatherable layer to an elastic layer, wherein the elastic layer is extended to crimp the gatherable layer when relaxing the layer. Neck-bonded laminates are made by combining the necked inelastic layer with an elastic film on the fiber layer. The elastic layer generally comprises an elastic film or an elastic nonwoven web. These elastic nonwoven laminates require the preparation of two or more separate nonwoven layers or film layers.

U. S. Patent No. 4,366, 814 to Riedel is a breathable elastic comprising at least 50 wt.% Stretchable fabric that can stretch at least 30 percent without tearing and at least 15 wt.% Elastomers impregnated in the fabric without filling holes in the fabric. Bandage materials are described.

U.S. Patent No. 5,910,224 to Morman discloses extensibility by applying an elastomeric precursor to a neckable material, such as a nonwoven web, necking the neckable material, and treating the elastomeric precursor by a method such as heating. A method of making a composite is described wherein the neckable material is in a necked state to form an elastomeric layer bonded to the necked material. Preferred elastomeric precursors include latex or thermoset elastomers. The elastomeric precursor is applied to the neckable material in an amount of 5 g / m 2 to about 50 g / m 2. The elastomeric layer typically penetrates the web at about 2 to about 10 fiber thicknesses, and the extent of penetration of the elastomeric precursor is controlled so as not to penetrate the side of the web opposite the side to which the elastomeric layer is applied. Thus, the resulting stretchable composite has a film-like feel on the side that includes the elastomeric layer and retains the original soft feel of the neckable material on the opposite side of the elastomeric layer.

European Patent Application Publication No. 0472942 provides compressibility in the Z-direction, including fibrous webs such as nonwoven webs of meltblown fibers saturated with polymeric materials such as elastomeric acrylic latex, polyurethane latex or nitrile rubber latex, and Elastomeric saturated nonwoven materials with recoverability are described.

Japanese Patent Application Laid-Open No. 47-24479 relates to a belt for use in conveyors and power transmission devices, manufactured by impregnating a needlepunched nonwoven with rubber or synthetic resin.

There is a continuing need for elastic sheet materials that can be manufactured economically, have soft stretchability and good retention, and have a fabric-like feel on both sides.

<Overview of invention>

The present invention

Providing a necked nonwoven substrate having a thickness, a first and a second outer surface, a machine direction and a machine direction, and an elongation in the machine direction of at least 30%,

Impregnating the necked nonwoven substrate substantially uniformly with a solution comprising an elastomeric polymer dissolved in a solvent, and

Solvent is removed by wet coagulation from the impregnated nonwoven substrate to deposit the elastomeric polymer substantially uniformly through the thickness of the nonwoven substrate without forming a substantially continuous elastomeric polymer layer on the first or second outer surface of the nonwoven substrate. (deposit) step

It relates to a method of forming an extensible nonwoven sheet comprising a.

The invention also

Having a thickness, a first and a second outer surface, a machine direction and a machine direction, an elongation in the machine direction of at least 30%, a basis weight of about 15 g / m 2 to about 100 g / m 2, and a broken nasal cavity Providing an easily extensible nonwoven substrate having a break tenacity of greater than 500 g / in,

Substantially uniformly impregnating a readily extensible nonwoven substrate with a solution comprising an elastomeric polymer dissolved in a solvent, and

The solvent is removed from the easily extensible nonwoven substrate by wet coagulation so that the elastomer is substantially uniform throughout the thickness of the nonwoven substrate without forming a substantially continuous elastomeric polymer layer on the first or second outer surface of the nonwoven substrate. Depositing polymer

It relates to a method of forming an extensible nonwoven sheet comprising a.

The present invention also relates to an extensible nonwoven sheet comprising a nonwoven substrate necked in the necked direction and impregnated with an elastomeric polymer substantially uniformly, wherein the extensible nonwoven sheet is 140% three times in the necking direction. After extending to, the ratio of the third cycle non-load force at 100% elongation to the third cycle load force at 100% elongation is 0.3: 1 or more.

The present invention also relates to an extensible nonwoven sheet comprising an easily extensible raw nonwoven substrate impregnated with substantially uniform elastomeric polymer, wherein the extensible nonwoven sheet is 30% three times in the machine direction in the extensible nonwoven sheet. After extending to, the ratio of the third cycle unloading force at 30% elongation to the third cycle loading force at 30% elongation is at least 0.15: 1.

In the present invention, an extensible composite nonwoven sheet is provided by impregnating a solution comprising a solvent and an elastomeric polymer in a necked nonwoven substrate or an easily extensible nonwoven substrate. The necked nonwoven substrate or the easily extensible nonwoven substrate is impregnated under conditions such that substantially uniform impregnation of the nonwoven substrate is achieved without forming a polymer layer on both surfaces thereof. After removal of the solvent, a breathable impregnated nonwoven sheet is obtained in which the high cycle unloading force and the textile-like feel are unexpectedly harmonized compared to the periodic load force (for good retention and smooth extensibility) in the machine direction. In addition, the sheets of the present invention are typically simpler and thinner to manufacture than conventional multilayer extensible laminates. For example, the sheet of the present invention has a typical thickness of about 0.25 to 0.75 mm, but the extensible laminate is generally thicker than 1.3 mm.

The term “polymer” as used herein generally includes homopolymers, copolymers (eg, blocks, grafts, random and alternating copolymers), terpolymers, and the like, and blends and modifiers thereof. However, the present invention is not limited thereto. Also, unless specifically limited otherwise, the term "polymer" shall include all possible geometrical forms of the material. Such forms include, but are not limited to, isotactic, syndiotactic, and irregular symmetry.

The term "polyester" as used herein is meant to include polymers wherein at least 85% of the repeating units are condensation products of dicarboxylic acids with dihydroxy alcohols having linking groups produced by the formation of ester units. This includes aromatic, aliphatic, saturated and unsaturated diacids and dialcohols. The term "polyester" as used herein also includes copolymers (such as block, graft, random and alternating copolymers), and blends and modifications thereof. A common example of polyester is poly (ethylene terephthalate) (PET), which is a condensation product of ethylene glycol and terephthalic acid.

The term "polyurethane" as used herein is meant to include block copolymers prepared by condensing a bifunctional polyol with a diisocyanate and a bifunctional chain extender, as described in detail below.

The term "polyolefin" as used herein is meant to mean both a series of nearly saturated open chain polymer hydrocarbons consisting solely of carbon and hydrogen. Typical polyolefins include, but are not limited to, polyethylene, polypropylene, polymethylpentene, and various combinations of ethylene, propylene, and methylpentene monomers.

The term "polyethylene" as used herein is meant to include homopolymers of ethylene as well as copolymers in which at least 85% of the repeat units are ethylene units.

The term "polypropylene" as used herein is meant to include homopolymers of propylene as well as copolymers in which at least 85% of the repeat units are propylene units.

As used herein, the term “elastomeric polymer” is stretchable to an elongated length that is at least about 160% of its relaxed non-bias length when molded into a sheet, fiber or film and subjected to a biasing force, When the biasing force is removed, it refers to any polymer that will recover at least 55% of its elongation. For example, a 1 cm sample of material can be stretched to 1.6 cm or more and will be stretched to 1.6 cm by the application of force and will return to a length of 1.27 cm or less upon removal of the force. There are many elastomeric materials that can be stretched much more than 60% of their relaxed length (eg, 100% or more), many of which are substantially at their original relaxation length, as soon as the stretching force is removed, eg For example, it will recover to within 105% of its original relaxation length.

As used herein, the term "nonwoven" or "nonwoven web" refers to a structure of individual fibers, filaments, or yarns that, in contrast to a knit or woven fabric, are placed in an irregular manner without an identifiable pattern to form a flat material. .

The term "spunbond" filament, as used herein, is used to extrude a molten thermoplastic polymeric material as a filament from a plurality of fine, generally circular spinneret capillaries, and then rapidly reduce the diameter of the extruded filament by stretching. It means the filament to be formed. Other filament cross-sectional shapes, such as oval, multileaf, and the like can also be used. Spunbond filaments are generally continuous and have an average diameter of greater than about 5 μm. Spunbond nonwovens or nonwoven webs are formed by irregularly stacking spunbond filaments on a collecting surface, such as a porous screen or belt. Spunbond webs are generally joined by methods known in the art such as hot rolling calendering the web or passing the web through a saturated-steam chamber at elevated pressure. In addition, the web may be spot bonded by heat at a number of heat bond points present across the spunbond fabric.

As used herein, the term "machine direction (MD)" refers to the direction in which the nonwoven web is produced. The term "cross machine direction (XD)" generally refers to a direction perpendicular to the machine direction.

The term "necking" as used herein applies a force to a nonwoven fabric, for example in parallel to the machine direction of the nonwoven fabric, to stretch the nonwoven fabric in the direction in which the force is applied, in a direction perpendicular to the stretching direction, eg For example, it refers to a method including reducing the width in the machine direction to adjust the width to the desired amount. The direction perpendicular to the stretching force is referred to herein as the "necking direction". Controlled elongation and necking can occur at room temperature or above or below room temperature, and the increase in overall dimensions in the direction of stretching is limited to the elongation needed to tear or rupture the fabric.

As used herein, the terms "necked nonwoven" and "necked nonwoven substrate" refer to any nonwoven shrunk in at least one direction by a process such as stretching. A "neckable nonwoven" is a nonwoven in which at least one dimension can be retracted in the necking process. The term "necking elongation" refers to a ratio determined by measuring the difference between the unnecked dimension and the necked dimension (measured in the necking direction), then dividing the difference by the unnecked dimension and multiplying the generated ratio by 100. The necked nonwoven is generally extendable in the necking direction in an amount corresponding to (but not in a linear relationship) the necking elongation during necking. The elongation of the necked nonwoven is elongated by stretching individual fibers in the nonwoven, breaking any fiber-fiber bonds in the nonwoven, or stretching the necked nonwoven in the necking direction as much as possible without tearing the nonwoven. It is measured as (%).

As used herein, the term "easy extendable nonwoven" refers to the "30% elongation" described in the Test Methods section, without any additional processing steps (such as necking) other than those typically used in nonwoven fabrication processes. Force of less than 200 g / in. (G / in), typically less than 100 g / in, determined by the " force required to " method to at least 30% (typically from about 60% to about 150%) without breaking Lateral elongated nonwovens. Elongation 50% means that a 10 inch wide sample can be stretched to 15 inches. Easily extensible nonwovens have a basis weight of from about 15 to about 100 g / m 2, typically from about 30 to 80 g / m 2, and the machine direction determined by the “rupture specific strength analysis” described in the test method section. Break specific strength is greater than 500 g / in. Easily extensible nonwovens can be spunlaced (also called hydroentangled), meltblown, or heat bonded nonwovens, which can be produced by such well known processes. Can be.

As used herein, the term "spunlace nonwoven" refers to a jet of high pressure water in a web (which may include preformed fabrics, spunmelt webs, airlaid webs, and carded webs) or batts. Point to the fabric formed by crashing. Easily extensible nonwovens include type 8075 Sontara® (Sontara is a registered trademark of EI DuPont de Nemours and Compamy), and Taipei, Taiwan Flat spunlaced nonwovens, article number 4055-T, manufactured by Sheng Hung Industrial Company.

The term "meltblown nonwoven" as used herein refers to a nonwoven formed by extruding a molten polymer through a die into a high velocity air stream of hot air or steam that converts the resulting filaments into fine, relatively short fibers. . The fibers are deposited on a moving screen or belt and then reinforced by calendering, embossing, hot air or other heat bonding processes.

As used herein, the term “heat bonded nonwoven” is melted upon application of heat by the presence or absence of pressure, for example by hot air, calendering, embossing, infrared heat, or other heat bonding processes to form a web or bat. It refers to a heat sensitive material that adhesively bonds the fibers to a reinforced nonwoven, such as a fabric or web of fibers containing a thermoplastic powder having a lower melting point than a specially processed low melting binder fiber or web fiber.

As used herein, the term "nonwoven substrate" refers to a substrate that may be a necked nonwoven substrate or an easily extensible nonwoven substrate.

The term "nonwoven" as used herein refers to a fabric that may be a necked nonwoven or an easily extensible nonwoven.

The term "wet coagulation" as used herein refers to a coagulant that is a non-woven substrate impregnated with a solution comprising an elastomeric polymer dissolved in a solvent, which is non-solvent for the elastomeric polymer but miscible with the solvent used to form the elastomeric polymer solution. Describe the process of contacting with. The coagulating solution is also chosen so as not to dissolve the nonwoven substrate. The coagulating solution causes the polymeric material to coagulate and the solvent to be removed into the coagulating solution. The coagulant is then removed from the polymer-impregnated nonwoven by methods such as air drying or heating.

Neckable nonwovens suitable for use in the present invention include spunbond webs, bonded carded webs, and hydroentangled webs. The neckable nonwoven is typically necked transversely using methods known in the art to achieve necking elongation of about 25 to about 75%, so that necking elongation of about 30% to about 300% is achieved. A nonwoven substrate is obtained. Neckable nonwovens useful in the present invention can be prepared from a number of thermoplastic polymers including non-elastomeric polyolefins such as polyethylene, polypropylene, ethylene copolymers, polyamides, polyesters, polystyrenes and poly-4-methylpentene-1. . For example, the neckable nonwoven includes polypropylene, polyester or polypropylene-polyethylene copolymer. In a preferred embodiment, the neckable nonwoven is a spunbond polypropylene fabric or carded heat bonded polypropylene or polyester fabric. The neckable starting nonwoven substrate typically has a basis weight of about 10 g / m 2 to about 50 g / m 2. Particular preference is given to relatively low basis weight neckable nonwovens, for example from about 10 g / m 2 to about 30 g / m 2. Nonwoven substrates are typically water vapor permeable. The neckable nonwoven substrate is generally necked to provide a necked nonwoven substrate having a basis weight greater than about 15 g / m 2.

Necked nonwovens are known in the art and are generally made by stretching the neckable nonwoven in the machine direction to provide a necked nonwoven that is necked in the machine direction. Examples of necking processes are disclosed, for example, in US Pat. Nos. 4,443,513 to Meitner, US Pat. Nos. 4,965,122, 4,981,747 and 5,114,781 to Moman. Preferred necking processes are disclosed in US Reissue Patent No. 35,206 to Hassenboehler Jr. et al. U.S. reissued patent 35,206 is a reissued patent of U.S. Patent 5,244,482 and is incorporated herein by reference. The nonwoven web necked according to Hassenboeller's method is also referred to herein as a "reinforced web".

Necked nonwovens can be manufactured using a relatively low cost process, and have a high degree of transverse extension and other extensions because they require a relatively low extension (load) force to extend the nonwoven in the transverse direction. Preferred over nonwovens. Necked nonwovens are also generally non-extensible in the machine direction. That is, less than about 5% elongation when applied to the bias force in the machine direction. Substantially extensible in one direction is highly desirable in certain end uses, as discussed below.

In a preferred embodiment, the necked nonwoven substrate is a reinforcing web made using the method described in Hassenboeller's patent. This method allows a bonded thermoplastic nonwoven web having a relatively low workability to pass through a heating zone, such as an oven, stretching the web in the machine direction while increasing the temperature of the web to a temperature between the softening point and the melting point of the polymer web. Plastically deforming the transversely oriented fibers and reinforcing (necking) the web in the machine direction. Stretching is performed by passing the web in band at a first linear velocity and withdrawing the web at a second linear velocity exceeding the first velocity. The ratio of the second speed to the first speed is, for example, about 1.1: 1 to about 2: 1. The starting bonded nonwoven web is a neckable non-elastomeric nonwoven fabric and has a strain elongation ratio of greater than 2500% / min and an elongation at break evaluated during hot drawing at temperatures above the softening point of the polymer web and at least 10 ° F. below the melting point during high temperature processing. It is chosen to be less than about 4.0: 1 and greater than about 1.4: 1. Elongation at break (strain) is, for example, 2 to 40%, typically 5 to 20%, based on test method ASTM D 1117-77 using an Instron tensile tester.

The fibers in the starting web can be joined by thermal bonding, such as fiber-fiber fusion, fiber entanglement, or point bonding. Typically, the fibers in the neckable nonwoven have a small average fiber diameter, for example less than about 50 μm. Bonding within the spunbond precursor is typically strong (eg, hot point bonding), which locally stretches, twists, and bends the filament segments without affecting web integrity. In spot bonding, the bond point and bond pattern are generally selected such that the area of the bond point is about 5 to about 25% of the web area. The shape of the junction can be diamondoid or many other shapes well known in the art.

The heat drawing step causes plastic deformation of the transverse fibers and reinforcement of the web, so that the majority of the fibers are generally aligned in the stretching direction (machine direction). The web is elongated and heat set in the longitudinal direction relative to the starting nonwoven and reinforced in the machine direction.

The elastic nonwoven sheet of the present invention can be made using a necked nonwoven substrate having a transverse elongation of 30% or more, for example 50% or more. The necking elongation of the nonwoven web during the reinforcing process, for example, corresponds to about 100% to about 300%, and 150% to 250% elongation, respectively, from about 50% to about 75%, typically from about 60% to 70%.

The basis weight of the necked nonwoven web may be at least three times greater than the basis weight of the neckable starting nonwoven web. The basis weight of the necked web is from about 15 g / m 2 to about 100 g / m 2, for example from about 20 g / m 2 to about 100 g / m 2, typically from about 25 g / m 2 to about 100 g / m 2. The basis weight of the necked nonwoven substrate is selected according to the desired end use. For example, when used as an elastic interliner, the basis weight of the necked nonwoven is typically between about 30 g / m 2 and 70 g / m 2, while for hygienic end uses such as diaper waistbands and the like. The basis weight is typically about 15 g / m 2 to 40 g / m 2. The basis weight of the necked nonwoven substrate should also be chosen to achieve the desired elasticity in the final impregnated nonwoven fabric. The higher the basis weight of the nonwoven substrate, the more elastomeric polymer can be impregnated into the nonwoven, thereby increasing the specific load of the impregnated nonwoven sheet.

The use of relatively low basis weight nonwovens in the necking process described in Hassenboeller's patent is preferred for producing the materials produced according to the present invention. After using these factors together and impregnating the elastomeric polymer, a stretchable nonwoven fabric having a relatively low force (load force) required to extend the material and a relatively high restoring force (non-load force) applied by the material when the material relaxes. This is provided. This feature is desirable for the end use expected for such materials. The relationship between unloading force and loading force is related to hysteresis of elastic nonwovens. For the preferred product of the present invention having a transverse elongation of at least 150%, the impregnated nonwovens are extended three times to 140% and relaxed between extensions, followed by specific load at 100% elongation versus load at 100% elongation. The force ratio is greater than 0.3: 1, for example greater than 0.45: 1.

Elastomeric polymers useful in the present invention include polyurethanes, styrene-butadiene block copolymers, and polyether-ester block copolymers. In a preferred embodiment, the elastomeric polymer is a polyurethane.

Elastomeric polyurethanes useful in the present invention react polymer polymers with diisocyanates to form capped glycols, dissolve the protected glycols (in a suitable solvent) and then protect the glycols with 2 active hydrogen atoms. It can be prepared by reacting a functional chain extender. Such polyurethanes are said to be "segmented" because they consist of "hard" urethane and urea segments derived from diisocyanates and chain extenders, and "soft" segments derived primarily from polymer glycols. Suitable solvents for preparing solutions of such polymers are amide solvents such as dimethylacetamide ("DMAc"), dimethylformamide ("DMF"), and N-methyl-pyrrolidone, but dimethyl sulfoxide and tetramethylurea Other solvents such as may also be used.

Polymer glycols used in the preparation of elastomeric polyurethanes include polyether glycols, polyester glycols, polycarbonate glycols and copolymers thereof. Examples of such glycols include poly (ethylene ether) glycol, poly (tetramethylene ether) glycol, poly (tetramethylene-co-2-methyl-tetramethylene ether) glycol, poly (ethylene-co-butylene adipate) glycol, Poly (2,2-dimethyl-1,3-propylene dodecanoate) glycol, poly (pentane-1,5-carbonate) glycol, and poly (hexane-1,6-carbonate) glycol.

Useful diisocyanates include 1-isocyanato-4-[(4-isocyanatophenyl) methyl] benzene, 1-isocyanato-2-[(4-isocyanatophenyl) methyl] benzene , Isophorone diisocyanate, 1,6-hexane diisocyanate and 2,4-tolylene diisocyanate.

The chain extender may be a diol or diamine. Useful diols include ethylene glycol, 1,3-trimethylene glycol, 1,4-butanediol and mixtures thereof. The use of diol chain extenders produces polyurethane. Useful diamines include ethylene diamine, 1,2-propanediamine, 2-methyl-1,5-pentanediamine, 1,3-diaminopentane, 1,4-cyclohexane-diamine, 1,3-cyclohexanediamine and Mixtures thereof. In this case, the resulting polymer is polyurethaneurea (a subgroup of polyurethanes). When polyether glycols and diamine chain extenders are used, the resulting polymer is polyetherurethaneurea, and when polyester glycols are used with diamine chain extenders, polyesterurethaneureas are produced. Monofunctional amine chain terminators such as diethyl amine, butylamine, cyclohexylamine and the like can be added to control the molecular weight of the polymer. In a preferred embodiment, the elastomeric polymer is a diamine-extended polyurethane elastomer.

Suitable solvents for preparing the elastomeric polymer solution include dimethylacetamide, dimethylformamide and N-methyl-pyrrolidone. The viscosity of the elastomeric polymer solution is directly related to the concentration of the polymeric material in the solution, so the solution viscosity affects both the degree of penetration of the polymer into the necked nonwoven or readily extensible raw nonwoven and the amount of polymer deposited thereon. Can give If the solution viscosity is too low, insufficient amount of elastomer may be deposited in the necked nonwoven substrate or the easily extensible raw nonwoven substrate, resulting in low specific load forces. If the solution viscosity is too high, the penetration of the solution into the nonwoven substrate may be reduced, resulting in incomplete or non-uniform impregnation of the polymer into the nonwoven substrate, or formation of a polymer layer on the nonwoven substrate surface. Solutions of elastomeric polymers that are impregnated into a necked nonwoven substrate or an easily extensible nonwoven substrate have a solution viscosity measured at 25 ° C., for example, from about 1,000 to 300,000 centipoise (“cP”), typically 10,000 to 40,000. cP. The solution may comprise about 5 to 20 weight percent of the polymer.

The necked nonwoven substrate or the easily extensible nonwoven substrate should be able to absorb the polymer solution and the polymer solution should be substantially completely and uniformly impregnated with the nonwoven substrate. Thus, the necked nonwoven substrate or the easily extensible nonwoven substrate must be treated otherwise such that the polymer solution is not absorbed into the uncoated or necked nonwoven or easily extensible nonwoven. Elastomeric polymer solutions and / or nonwovens can include surfactants to promote impregnation of the web with the polymer solution. Suitable surfactants include nonionic wetting agents such as polymeric surfactants.

Small amounts of additives such as pigments, antioxidants, ultraviolet stabilizers and lubricants can be added to the elastomeric polymer solution, provided these additives do not impair the advantages of the present invention.

In the elastomeric polymer solution there may be dispersed very short fine fibers, for example cellulose fibers from cotton pulp, cottonseed, or other synthetic or natural fibers less than about 0.10 inches (2.5 mm) in length, for example less than 0.5 mm. have. The fibers are typically small enough to penetrate the nonwoven during the impregnation step. Short fibers may be added to the polymer solution in an amount sufficient to deposit about 3 to about 12 weight percent of short fibers in the impregnated nonwoven sheet, calculated based on the total weight of the nonwoven / elastomer polymer composite. Short fibers are typically added at about 10 to about 30 weight percent, such as about 10 to about 20 weight percent, to the elastomeric polymer solution, based on the total weight of the short fibers, elastomeric polymer and solvent. The nonwoven sheet of the present invention prepared by impregnating a necked nonwoven fabric or an easily extensible nonwoven fabric with an elastomeric polymer solution containing powdered cellulose has a softer feel than that produced using an impregnation solution containing no short fibers. Can have. One example of a very fine fibrous particulate material suitable for use in polymer solutions is available under the trade designation “Arbocel 30” available from J. Rettenmaier USA (Schocraft, Michigan, USA). Powdered cellulose.

Any suitable method of coating the elastomeric polymer solution on a necked nonwoven substrate or an easily extensible nonwoven substrate or otherwise impregnating the necked nonwoven substrate or an easily extensible raw nonwoven substrate may be that the fabric is uniformly impregnated and coated. It can be used as long as it is not concentrated on one or the other surface of this necked nonwoven substrate or an easily extensible nonwoven substrate. Although coating methods may be used to treat the nonwoven substrate with the elastomeric polymer solution, the solution and nonwoven characteristics and coating process conditions may be selected so that the polymer solution wets the nonwoven substrate completely or otherwise is fully absorbed or induced into the nonwoven substrate. Care must be taken not to form a polymer layer on either surface. In general, the amount of polymer solution applied during coating can be controlled using a coating tool fixed at a predetermined distance on the necked nonwoven or easily extendable raw nonwoven substrate. The solution may also be mechanically pressed into the nonwoven substrate. Rollers, platens, scrapers, knives and the like can be used as coating tools in the method of the present invention. Spraying the solution onto the nonwoven substrate may also be effective if the elastomeric solution is impregnated substantially completely and uniformly on the nonwoven substrate. Spraying force can be adjusted to obtain good penetration. The fibrous web is immersed or otherwise immersed in a tank containing the elastomeric polymer solution and then, for example, immersed and squeezed between nip rolls to remove excess polymer solution, known in the art. The process can be used to impregnate the elastomeric polymer solution with the nonwoven substrate. This method is desirable to minimize the distance between both sides of the stretchable composite nonwoven sheet.

The necked nonwoven substrate or the easily extensible nonwoven substrate is impregnated with a polymer solution sufficient to provide the desired nonload / load force ratio to the final impregnated nonwoven sheet. The nonwoven substrate is typically impregnated with a polymer solution sufficient to deposit about 10 to about 80 weight percent, such as about 30 to about 50 weight percent of the elastomeric polymer, based on the total weight of the elastomeric polymer and the nonwoven substrate. If the amount of elastomer is too small, the ratio of unloading force to loading force may be undesirably low, and if the amount of elastomer is too large, the texture of the sheet surface may be undesirably tacky. The solution concentration and / or the amount of solution impregnated into the necked nonwoven or easily extensible raw nonwoven substrate can be adjusted to achieve the desired polymer content in the impregnated sheet. For example, using lower polymer concentrations in the solution while retaining similar elastomer content on the impregnated sheet by using wider gaps between the nip rolls during application of the solution, It was observed that a product with improved coordination was provided.

Once the nonwoven substrate is impregnated with a solution comprising a solvent and an elastomeric polymer, the solvent is removed. After the solvent is removed by wet coagulation, the coagulation liquid is removed. Wet coagulation is surprisingly softer than heat drying and provides a product with a more cloth-like feel. Wet coagulation processes are well known in the art and are commonly used in the manufacture of artificial leather. Water is preferred as a coagulating liquid for reasons of ease of handling and low cost. Other suitable coagulants include methanol, ethanol, isopropanol, acetone or methylethyl ketone. The coagulation rate can be changed by addition of solvents for elastomeric polymers such as dimethylformamide, dimethylacetamide or N-methyl-pyrrolidone or other additives such as surfactants to the coagulation solution. In addition, it is possible to change the coagulation rate by adjusting the temperature of the coagulation bath. The slower the coagulation rate, the more attractive the impregnated nonwoven fabric after removing the solvent.

In the impregnated nonwoven sheet of the present invention, the elastomeric polymer phase uniformly distributed throughout the necked nonwoven substrate or the easily extensible raw nonwoven substrate is breathable. Also, the impregnated nonwoven sheet is typically water vapor permeable.

By raising the fibers of the surface of the sheet impregnated by sanding or napping, the texture of the impregnated nonwoven sheet can be improved to obtain a softer feel. The napping treatment involves passing the fabric over a rotating roll that contains small metal points that effectively brush the fabric to lay the fibers on the surface. In the sanding treatment, the metal brush is replaced with a rolling roll coated with sandpaper. Typically, the impregnated fabric is naped or sanded on both sides. For example, the fabric may be sanded with sand of 80 to 200 grit.

Extensible impregnated nonwoven sheets of the present invention typically have a basis weight of about 40 g / m 2 to about 100 g / m 2. They are particularly useful for waistbands or side panels of diapers and other personal care garments such as underwear. Diapers are commercially assembled in long, high-speed lines where various diaper components are typically added in the machine direction to prevent process slowdown. This is especially the case for elastomeric materials which generally elongate before insertion. Diapers generally contain about 20 or more individual components that must all be correctly positioned in the correct position of the diaper during the high speed manufacturing process. This is much easier to achieve if the ingredients (tape, sheets, fibers, etc.) are fed in the same direction as the diaper moves. In order to add the component in the machine direction (eg waistband), it is desirable that the material itself be stretched in the machine direction so that it can be supplied to the diaper manufacturing process as a tape in the machine direction. For example, the tape may be a long piece that is 7 inches wide and only 1 inch long, which is cut from the sheet and adhered to the diaper or other disposable underwear. In this process, in order to facilitate the supply into the process, it is also preferred that the diaper component supplied into the process is substantially non-extensible in the machine direction. The extensible nonwoven sheet of the present invention is particularly suitable for use in the process because it is substantially non-extensible in the machine direction and has a high recoverable stretch in the cross-machine direction.

The stretchable nonwoven sheet of the present invention is also useful as an elastic interliner in various garments, especially in jackets and coats. An interliner is a fabric inserted between the outer and inner layers of a garment that is intended to impart or improve shape retention, padding, thermal comfort, rigidity or bulkiness to the garment. The stretchable nonwoven sheet of the present invention is particularly useful for this use because of its low cost and the ability to provide stretchability to comply with permanent elasticity and body circumference dimensions.

The stretchable nonwoven sheet within the scope of the present invention may be provided to be highly compliant with the body shape and may serve therapeutic purposes by elastically applying elastic pressure over the injured or injured area. Thus, stretchable nonwoven sheets that fall within the scope of the present invention may be useful in medical products and applications. Such products and applications include, for example, tapes including adhesive and cohesive tapes, wraps including compression wraps, bandages, dressings including surgical and wound dressings, and incisions that adhere to the skin around the surgical incisions. Surgical fabrics, including fabrics, may be included.

Test Methods

Force required to stretch 30%

This analysis was performed on an Instron model 5565 equipped with a Merlin data acquisition software system. Merlin systems and instrument hardware are both available from Instron Corporaiton (Braintree, Massachusetts, USA). A nonwoven sheet sample of 1 inch ± 0.05 inches (2.54 cm ± 0.13 cm) and about 8 inches (20.32 cm) in length was fixed to a jaw of an Instron machine at a sample length of 3.00 inches (7.62 cm). Samples were prepared such that the length of the sample was aligned in the machine direction of the nonwoven. Samples were stretched at a rate of 6 inches / minute (15.24 cm / minute) to elongation 30%. Force g at elongation 50% was recorded.

Breaking Strength Analysis

This analysis was performed on an Instron Model 5565 equipped with a Merlin data acquisition software system. Merlin systems and instrument hardware are both available from Instron Corporation (Braintree, Massachusetts, USA). A nonwoven sheet sample of 1 inch ± 0.05 inch (2.54 cm ± 0.13 cm) and about 8 inch (20.32 cm) in length was fixed to a jaw of an Instron machine at a sample length of 3.00 inch (7.62 cm). Samples were prepared such that the length of the sample was aligned in the machine direction of the nonwoven. The sample was stretched at a rate of 6 inches / minute (15.24 cm / minute) until the sample was torn in two parts, and the maximum force in grams (g) was recorded.

Basic weight

The rectangular sample of the nonwoven sheet of about 1.0 inches by 8.0 inches (2.54 cm by 20.32 cm) was carefully relaxed to avoid wrinkles or wrinkles. The length and width of the sample were measured to millimeters and the sample was weighed to one tenth of a milligram. The weight was divided by the calculated area and the result was expressed in g / m 2 up to 0.1 g.

Load  And No load  analysis

This analysis was performed on an Instron Model 5565 equipped with a Merlin data acquisition software system. Merlin systems and instrument hardware are both available from Instron Corporation (Braintree, Massachusetts, USA). A nonwoven sheet sample of 1 inch ± 0.05 inch (2.54 cm ± 0.13 cm) and about 8 inch (20.32 cm) in length was fixed to a jaw of an Instron machine at a sample length of 3.00 inch (7.62 cm). Samples were prepared such that the length of the sample was aligned in the machine direction of the nonwoven. The sample was stretched at a rate of 6 inches / minute (15.24 cm / min) to elongation 140% and then relaxed to its original length. Repeat this two more times and record the force (load force) applied by the material in the extension cycle in the third cycle at 50%, 100% and 135% elongation based on the original sample length and similarly in the third relaxation cycle. The force (non-load force) applied by the material was also recorded at the same elongation. Results (g) are shown as the third cycle load and non-load force at the appropriate elongation.

Shinto analysis

Mark the two points about 4.0 inches (10.2 cm) away from both ends of the fabric with a pen on a relaxed piece of nonwoven fabric of width 1 inch (2.54 cm) and length of approximately 8 inches (20.32 cm) without wrinkles or creases. It was. Then, both ends of the fabric were firmly held with the thumbs and index fingers of both hands to extend the sample sufficiently but not to tear or cause any similar mechanical damage. Maximum elongation was apparent to the person performing the test as the resistance to extension by the fabric was significantly increased. Then, the length between two mark points of the nonwoven was measured, and the elongation (%) was calculated by the following formula (initial length is 10.2 cm):

% Elongation = {(extended length-initial length) / initial length} X 100%

When the elongation was measured in the necking direction, the fabric sample was cut by aligning the length in the machine direction (necking direction).

Example  One

A 30-inch (76.2 cm) wide, 15 g / m 2 wetted spunbond polypropylene nonwoven made by Avgol Nonwovens, Israel, was 89 feet / minute (27 m / min). Feed through the nip roll at a speed, followed by a second nip roll operated at 115 ft / min (35 m / min) through a forced convection oven at 72 inches (1.83 cm), 290 ° F. (143 ° C.) Passed through a roll. In this process, a 30 inch (76.2 cm) wide nonwoven fabric was uniformly and smoothly reinforced ("necked") to 10 inches wide (25.4 cm) in the transverse direction. A minimum force could be applied to extend back to its original 30 inches (76.2 cm) transverse width. The necked nonwovens were essentially zero in machine direction elongation and had a basis weight of 32.0 g / m 2.

Poly (tetramethylene ether) glycol of 1800 molecular weight, 1-isocyanato-4-[(4-isocyanatophenyl) methyl] benzene (1.69 using a 15 mil (0.38 mm) doctor knife Mole ratio of diisocyanate to glycol), chain extenders (9: 1 mole ratio of ethylene diamine and 2-methyl-1,5-pentanediamine) and 20% by weight of ureadimethyluremamide (DMAC) derived from diethylamine The solution was coated on one surface of the necked nonwoven. The following additives were also used: polymers of bis (4-isocyanatocyclohexyl) methane) and (3-t-butyl-3-aza-1,5-pentanediol) (Methacrol®) 2462B, a registered trademark of E.I.Dupont Nemoas & Co.) 0.5 wt%, titanium dioxide 0.3 wt%, silicone oil 0.6 wt%, 2,4,6-tris (2,6-dimethyl-4-t-butyl -3-hydroxybenzyl) isocyanurate (Cyanox® 1790, registered trademark of Cytec Industries) 1.4 wt%, and 4 wt% mixture of huntite and hydromagnesite % (All% are based on polyurethaneurea weight). The polyurethaneurea-DMAC solution fully wetted the nonwovens.

The coated nonwoven was suspended in air substantially vertically for about 1 minute to allow the polymer solution to fully penetrate into the nonwoven and then immersed in a 70 ° F. (21 ° C.) bath of 40 volume% DMAC in water. After 1 minute, the impregnated fabric was continuously transferred to 30% by volume, 20% by volume and 10% by volume of DMAC / water solution for 1 minute and finally soaked in 100% water bath for 2 minutes. The impregnated fabric was dried in air at room temperature.

The resulting impregnated nonwoven sheet exhibited the same texture and texture on both sides (dry, textile-like). From the photograph of the cross section of the impregnated nonwoven sheet, the thickness of the material showed that the composite structure was uniform and substantially free of zones of continuous polyurethane on both surfaces.

The nonwoven sheet was then lightly sanded with 220 grit sandpaper. The resulting material showed a noticeably softer texture, and visual observation showed that there were a large number of individual short fibers protruding from the surface as compared to a perfectly smooth surface without fibers protruding prior to sanding treatment. Unexpectedly, this treatment succeeded in providing a softer feel without significantly compromising the visual aesthetic or elastic characteristics of the sheet.

The basis weight of the resulting impregnated nonwoven sheet was 71.4 g / m 2, indicating that the polyurethaneurea content was 39.4 g / m 2, or about 55% by weight of the elastomeric polymer.

The resulting material was stretched by hand in the machine direction, resulting in about 160-180% elongation.

Load and non-load analysis provided the following results:

3rd cycle Load

Elongation% Load force (g) 50 67.3 100 211.2 135 409.7

3rd cycle No load

Elongation% Specific load capacity (g) 50 22.7 100 114.7 135 340.7

As a result of comparing the data in the table, the ratio of specific load to loading force at 100% elongation was 0.54.

Example  2

번호 Hung Industrial Company (Taiwan Sheen-Lin District Hou River Street 116) Item No. 4055-T, 55 g / m 2 A portion of a 10 inch (25.4 cm) wide roll of flat spunlace nonwoven, approximately Thirty feet in length were used in this example, which was run continuously. The nonwoven substrate was first obtained from INVISTA Inc. (Wilmington, Delaware, USA), T-162 Lycra (registered trademark) in dimethylacetamide (DMAC) with a solid content of 12.5%. ) Was immersed in the solution. The fabric speed was 3 ft / min and the total fabric length in the bath was about 6 inches. Removal of excess polymer solution was accomplished by passing the impregnated fabric through a nip roll at 0.007 inch intervals.

The resulting impregnated fabric was then passed through a bath of 40% DMAC dissolved in water followed by two separate baths of 100% water. The fabric speed through these baths was 3 ft / min. The total fabric length in each bath was 8 feet. All baths were operated at room temperature, about 72 ° F. The resulting fabric was air dried to obtain a breathable stretchable nonwoven fabric with attractive elastic properties and a basis weight of 80 g / m 2 (T-162 Lycra® 45 wt%).

As a result of manual elongation analysis of the resulting elastic nonwoven in the machine direction, the elongation was 50 to 60%. The loading and non-load forces in the third cycle are performed as described in the test method section, except that the sample is stretched to a maximum elongation of 50%, and the load and non-load resilience at 20%, 30% and 40% elongation is increased. Recorded. This modified load and unload force analysis gave the following results:

3rd cycle Load

Elongation% Load force (g) 20 92.6 30 227.2 40 425.9

3rd cycle No load

Elongation% Specific load capacity (g) 20 20.0 30 75.9 40 192.0

As a result of comparing the data in the table, the ratio of specific load to loading force at elongation 30% was 0.33.

Claims (11)

After the elastomeric polymer comprises a substantially uniformly impregnated necked nonwoven substrate and extends to 140% three times in the necking direction, the third cycle unloading force at 100% elongation to the third cycle load at 100% elongation An extensible nonwoven sheet for use in medical applications with a force ratio of at least 0.3: 1. The stretchable nonwoven sheet of claim 1, wherein the ratio of non-load force to load force is at least 0.45: 1. The elastomeric polymer comprises an easily extendable nonwoven substrate that is substantially uniformly impregnated, and extends 50% three times in the machine direction, and then at a third cycle non-load force at 30% elongation versus 30% elongation. An extensible nonwoven sheet for use in medical applications, wherein the ratio of third cycle loading forces is at least 0.15: 1. 4. The stretchable nonwoven sheet of claim 3 wherein the ratio of non-load force to load force is at least 0.3: 1. 4. The stretchable nonwoven sheet of claim 1 or 3 formed in a medical product. 6. The incision according to claim 5, wherein the medical product is a tape including adhesive and cohesive tapes, wraps including compression wraps, bandages, dressings including surgical and wound dressings, and incisions attached to the skin around the surgical incisions. A stretchable nonwoven sheet selected from the group consisting of surgical fabrics, including fabrics. A medical tape formed from the stretchable nonwoven sheet of claim 5. A medical wrap formed from the stretchable nonwoven sheet of claim 5. A bandage formed from the stretchable nonwoven sheet of claim 5. A dressing formed from the stretchable nonwoven sheet of claim 5. A surgical fabric formed from the stretchable nonwoven sheet of claim 5.