MXPA06011054A - Letterpress application of elastomeric compositions - Google Patents

Abstract

The invention provides a process to deliver an elastomeric composition to a substrate. The elastomeric composition is cooled. The cooling also results in substantially complete transfer of the elastomeric composition from the pattern roll to the substrate with a resulting reduction in elastomer degradation.

Description

TYPOGRAPHICAL APPLICATION OF ELASTOMERIC COMPOSITIONS FIELD OF THE INVENTION The present invention relates to a method for forming an elasticized composite material through the transfer of elastomeric compositions onto a substrate by typographic application. In this process, an elastomeric composition of the raised surface elements of a patterned roller is practically completely removed, ie, the residual elastomer is less than 10%. In certain embodiments, the composite material is then gradually stretched to disintegrate, at least partially, the structure of the substrate, in order to reduce its resistance to stretching. Laminated composites are useful for disposable articles, such as disposable absorbent articles, including diapers, coveralls, trainers, incontinence briefs, catamenial garments, baby bibs and the like, as well as other disposable and durable articles, particularly garments that include cloths and surgical garments, and sportswear, clothing and the like.

BACKGROUND Disposable absorbent products (eg, disposable diapers) generally include elasticized materials, such as elastic strands, in the waist region and the folds regions, which allow a comfortable fit and a proper seal to the wearer's body. The absorbent articles of the underpants type also include elasticized materials in their lateral portions to facilitate their placement and extraction providing a continuous adjustment of the article. Stretch materials have also been used in the portions of the diaper panels with tape for an adjustable fit of the article. Useful elastified materials include elastomeric films, non-woven fabrics, natural or synthetic rubber strands, elastic lightweight fabric and the like. Generally, these stretched regions are manufactured separately and adhered to the diaper using adhesives. In most cases, these designs provide a uniform and unidirectional elasticity. Also, the disposable and durable garments also use elastic elements for a better fit and greater comfort. An alternative approach that can provide non-uniform and multidirectional elasticity in US co-pending patent applications has been discussed. num. of series 10/288095, 10/288126 and 10/429433. This approach consists in the hot melt printing of one or more thermoplastic elastomers on a substrate, followed by a gradual stretching of the elasticized substrate which confers the elasticity properties of the elastomer to the substrate in a somewhat magnified form. Suitable printing processes described herein include direct rotogravure, rotogravure by composition and flexographic printing. Each of these printing methods allows the deposition of a predetermined amount of an elastomer in any shape and direction, which provides a wide variety of design flexibility, which in turn improves the diaper fit in general. However, improvements are still needed. It is desirable that the transfer of said elastomeric composition from the means used to apply the elastomer to a substrate is practically complete. Otherwise, the elastomeric composition can oxidize and cause color degradation, or suffer degradation of other properties. Such degradation, which may be the result of incomplete transfer, is more likely if the application medium is heated. Without being limited by theory, it is therefore important to understand the mechanism of transferring an elastomer from an application medium to a substrate. During this transfer, three forces are relevant. These forces include: i) the adhesive force between the surface of the application medium and the elastomer; ii) the adhesive strength of the elastomer (ie, the strength of an isolated portion of an elastomeric composition to separation into two smaller portions), and iii) the adhesive force between the elastomer and the substrate and / or the strength of the substrate. In order to satisfactorily transfer an elastomer to a substrate, the adhesive strength of the elastomer or the adhesive force between the elastomer and the surface of the application medium, either or both, must be less than the adhesive force between the elastomer and the elastomer. the substrate and / or the strength of the substrate. Generally, this problem has been solved with the use of hot printing processes in which the adherent strength of the heated elastomer has a sufficiently low value because the elastomer has been kept in a liquid or semi-liquid state. Therefore, the transfer of an elastomeric composition from an application medium to a substrate is usually achieved through an adhesion failure of the elastomer at the transfer point of the application medium to the substrate, and a portion of the elastomer remains on the surface of the application medium. The aforementioned conditions usually occur during, for example, rotogravure printing of elastomeric adhesives, in which the viscosity is relatively low and the adhesive has a strong affinity with the walls of the rotogravure elements, and also the substrate. It is important to note that adhesive failure means that there is a residual portion of the adhesive in the application medium that has not been transferred. On the other hand, elastomeric compositions having a good elasticity tend to have a higher viscosity at a certain temperature than a typical elastomeric adhesive. As a reference, typical thermoplastic elastomers used in diapers have viscosities in excess of 1000 Pa at 175 ° C. A higher viscosity results in a higher adherent strength of the elastomer and a need to heat it to a higher application temperature to ensure adherent failure. This dynamic represents a problem for printing by conventional direct rotogravure of high viscosity materials, since a point is reached where the adhesive strength of the elastomer exceeds its adhesive strength with the substrate or exceeds the strength of the substrate. In turn, said conditions make the elastomer unable to bind to the substrate or damage said substrate. On the other hand, if the temperature is increased to decrease the adhesive strength, the temperature of the application of the elastomeric composition may exceed the melting point of the substrate, which will cause the substrate to be damaged or will cause thermal degradation of the elastomer. Therefore, an application process is needed that can deposit the high viscosity elastomeric compositions on the substrates, without damaging said substrates.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing process of an elasticized composite material, wherein said method comprises in one embodiment: A manufacturing process of an elasticized composite material that includes the following steps of a) providing a first substrate with a first and a second opposing surfaces; b) providing a typographic adhesive application system, comprising a patterned roller, wherein at least a portion of the outer surface of the patterned roller comprises a predetermined pattern of raised surface elements and a pinch roller, and each of the rollers have an outer surface with a surface temperature of the roller; c) depositing a molten non-adhesive elastomeric composition on the outer surface of the applicator roll, wherein the composition has an application temperature and a release force of less than about 3 N / cm, and where the application temperature is higher than the temperature of the application. surface temperature of the applicator roller; d) transferring a portion of the composition of the applicator roller to the support areas of the raised elements, in such a way as to cover the surface of the raised surface elements where the composition presents adherent faults during the transfer, and in such a way that a portion of the composition also remains in the applicator roll; e) cooling the transferred portion to a temperature between the temperature of the application and the surface temperature of the patterned roller, and f) contacting the first surface of the substrate and the raised elements with the coated surface, so as to transfer practically completely the elastomeric composition of the patterned roller to the first surface.

BRIEF DESCRIPTION OF THE FIGURES Although the specification concludes with the claims that clearly indicate and claim the object considered as the present invention, it is believed that the invention will be better understood from the following description taken into account together with the accompanying figures, in which: Figure 1 is a schematic view of an apparatus for carrying out one embodiment of the process of the present invention. Figure 2 is a perspective view of an apparatus for carrying out the process of the present invention. Figure 3 is a perspective view of an apparatus for gradually stretching an elasticized substrate produced in accordance with the process of the present invention. Figure 4a is a perspective view of a sample holder used in the adhesion strength test. Figure 4b is a perspective view of a jaw used in the adhesion strength test.

DETAILED DESCRIPTION OF THE INVENTION Definitions The term "disposable" as used herein refers to products that, in general, are not designed to be washed or otherwise recycled or reused for their original function, ie, are preferably designed to be disposed of after about 10 uses or less, or more preferably after about 5 uses or less, or even more preferably after about a single use. It is preferred that these disposable articles are recycled, composted or disposed of in a manner compatible with the environment. As used herein, the term "disposable absorbent article" refers to a device that generally absorbs and retains fluids. In certain cases the phrase refers to devices that are placed on the body or close to the body of the user to absorb and contain the excretions or exudates evacuated from the body and includes personal care items, such as adjustable diapers, trainers diapers, trainers underpants, swimming diapers, adult incontinence articles, feminine hygiene items and the like. In other cases, the term also refers to protection or hygiene items such as bibs, cloths, bandages, wrappings, wound dressings, surgical drapes and the like. The term "adhesive" refers to materials that, when evaluated in accordance with the adhesion strength test described in the METHODS section TEST included below, have a peel force greater than 3 N / cm. The term "substrate" as used herein, refers to a material that includes a natural or synthetic element or any combination of these, for example, nonwoven fabric wefts, woven wefts, knits, films, laminates of films, non-woven fabric laminates, sponges, foams and any combination of these. The term "fibrous substrate" as used herein, refers to a composite material of a multiplicity of fibers which may be a natural or synthetic material or any combination thereof, for example, nonwoven webs, woven webs, knits and any combination of them. The term "non-woven fabric" as used herein refers to a material made of continuous and / or discontinuous fibers, without being woven or hatched by processes such as air laying, wet laying, spunbonding, carding and melting by blowing. A nonwoven fabric web may comprise one or more layers of nonwoven fabric, characterized in that each layer may include continuous and / or discontinuous fibers. The non-woven fabric webs may also comprise bicomponent fibers, which may have a fiber-like core structure, side-by-side or other known fiber structures. As used herein, the term "elastic" or "elastomeric" refers to any material that upon application of a deflection force may stretch to an expanded length of at least 160 percent of its original length in a relaxed state. , without ruptures or breaks, and that when the force is applied, it recovers at least 55% of its elongation, preferably it practically recovers until it returns to its original length, which will be less than 120 percent, preferably less than 110 percent and more preferably less than about 105 percent of the original length in the relaxed state. As used herein, the term "non-elastic" refers to any material that does not meet the above definition of "elastic". As used herein, the term "elastomer" refers to a polymer with elastic properties. As used herein, the term "extensible" or "elongable in non-elastic form" refers to any material that by applying a deflection force to stretch it more than about 110 percent of its length in relaxed original state, will show a permanent deformation, including elongation, rupture, rupture and other defects in its structure or changes in its tension properties. The terms "typography" or "typographic application system" refer herein to means of application where a material is transferred to a substrate from an apparatus comprising a predetermined pattern of raised surface elements on a metal roll surface, wherein the shape of each element defines the shape of the material transferred. The term "strangulated material" refers to any material that has been narrowed in one direction by the application of a tensioning force. The terms "machine direction" or "MD" as used herein refer to the direction of material flow during a process. The terms "cross machine direction" or "CD" refer to a direction perpendicular to the machine direction.

Substrate Substrates (i.e., a first substrate or any additional substrate layer) suitable for use in the processes claimed herein have first and second opposing surfaces and can be selected from the group comprising fabric, films, knitted fabric, woven fibrous webs, non-woven fibrous webs (including air-laid, wet-laid, carded, blow-molded, and spun-bonded), or combinations thereof. In some modalities, the substrate is an expandable nonwoven fabric web comprising polyolefin fibers and / or filaments, such as polyethylene, polypropylene, etc. The release substrate can also be a laminate of nonwoven fabric film, which can be used, for example, as an outer covering of a disposable diaper, a trainer brief, an adult incontinence product, etc. Ideally, the substrate should have a thickness ranging from about 0.05 mm to 2 mm, preferably from about 0.1 mm to 1 mm, and most preferably from about 0.1 mm to 0.5 mm.

Elastomeric Composition The elastomeric composition of the present invention is characterized by having a peel force of less than about 3 N / cm, more preferably, less than about 2 N / cm, even more preferably, less than about 1 N / cm, and most preferably, less than about 0.8 N / cm. (The methodology used to determine the release force of these elastomeric compositions is detailed in the section METHODS OF TEST included below). As detailed below, it is believed that said relatively low peel force is necessary to achieve a practically complete transfer from a patterned roll to a substrate. Suitable elastomeric compositions comprise thermoplastic elastomers selected from the group comprising block copolymers of styrene with a soft block comprising an olefin (preferred olefins include isoprene, butadiene, ethylene, propylene, butylene and isobutylene), polyolefins catalyzed by metallocene, polyesters, polyurethanes, polyetherramides, and combinations thereof. The block copolymers of styrene can be diblock, triblock, tetrablock or any other multi block copolymer containing at least one block of styrene. These multi-block copolymers include linear multiple block copolymers and branched copolymers, where the plurality of blocks leave a central block, commonly known as star polymers. Examples of styrene block copolymers include styrene butadiene styrene, styrene-isoprene-styrene, styrene-ethylene / butylene-styrene, styrene-ethylene / propylene-styrene, and the like. Commercially available block copolymers of styrene include KRATON®, from the Shell Chemical Company of Houston, TX; SEPTON®, of Kuraray America, Inc. of New York, NY, and VECTOR®, of Dexco Chemical Company of Houston, TX. The commercially available metallocene-catalyzed polyolefins include EXXPOL® and EXACT®, exxon chemical company of Baytown, TX; AFFINITY® and ENGAGE®, from Dow Chemical Company of Midland, Ml. Polyurethanes include TINN® from Noveon, Inc. of Cleveland, OH. Polyether amides include PEBAX®, from Atofina Chemicals of Philadelphia, PA. Among the polyesters available on the market are HYTREL®, from E. I. DuPont de Nemours Co. of Wilmington, DE. The elastomeric compositions may further comprise process additives and / or process oils to adjust the melt viscosity of the compositions to the desired values. These include conventional processing oils, such as mineral oils, as well as other oils and waxes derived from petroleum, such as paraffinic oil, naphthenic oil, petrolatum, microcrystalline wax, paraffinic wax or isoparaffin wax. Synthetic waxes, such as Fischer-Tropsch wax; Natural waxes, such as spermaceti, carnauba, ozocerite, beeswax, candelilla wax, ceresin, esparto, ouricuri, rezowax and other waxes known in the mining and minerals industry are also suitable for use in the present. It is also possible to use olefinic oligomers and low molecular weight resins. The oligomers may be polypropylenes, polybutylenes, hydrogenated isoprenes, hydrogenated butadienes or the like with a number average molecular weight of between about 350 and 8000. In one embodiment, a solvent with phase change is used as a processing aid. It can also be incorporated into the elastomeric composition to lower the melt viscosity, rendering the composition processable at a temperature of 175 ° C or lower, without practically compromising the elastic and mechanical properties of the composition. In general, the phase change solvent shows a phase change at temperatures that vary approximately between 40 ° C and 250 ° C. An exposure of the phase change solvents can be found in the U.S. patent application. series 10/429432, filed July 2, 2003. In some embodiments, the weight ratio between the thermoplastic elastomer and the processing oil or the processing aid (eg, a phase change solvent) in the elastomeric composition usually varies approximately between 10: 1 and 1: 2, preferably approximately between 5: 1 and 1: 1, and more preferably, approximately between 2: 1 and 1: 1. In addition, the elastomeric composition may comprise stabilizers and the like. For example, the stabilizers may include antioxidants and light stabilizers. Suitable antioxidants include phenols with steric hindrance. A commercially available antioxidant suitable for use in the elastomeric compositions of the present invention is IRGANOX 1010, distributed by Ciba Specialty Chemicals North America of Tarrytown, NY. Suitable light stabilizers include light hindered amine stabilizers. A commercially available UV light stabilizer is TINUVIN 123, also distributed by Ciba Specialty Chemicals North America. Elastomeric compositions suitable for use in the present invention are also practically free of tackifying agents, in order to help ensure that adhesion failure on the surface of the patterned roller is reliably achieved. As used herein, the term "substantially free of tackifying agents" means that the elastomeric composition has less than about 5% by weight of a material commonly recognized in the adhesive industry as a tackifier. As is known, the tackifying agents are added to the adhesive formulations to increase the adhesion of said formulations. Materials with commercial utility as tackifying agents include: rosin resins, coumaron-indene resins, terpene resins and hydrocarbon resins. In Example 1, the release properties of the suitable elastomeric compositions are compared with the elastomeric adhesives of the prior industry. Optionally, the elastomeric composition may further comprise low molecular weight elastomers or elastomeric precursors of the aforementioned thermoplastic elastomers and optional crosslinking agents, or combinations thereof. For example, the thermoplastic elastomers described in the copending US patent serial request no. 10/610605, filed under the name of Ashraf, et al. on July 1, 2003, comprising an elastomeric block copolymer with at least one hard block and at least one soft block, a macro-initiator, a processing oil and, optionally, a thermoplastic polymer and / or a crosslinking agent containing an elastomeric precursor. The number average molecular weight of low molecular weight elastomers or elastomeric precursors ranges from about 45,000 to 150,000. In some embodiments, the weight ratio between thermoplastic elastomers and low molecular weight elastomers or elastomeric precursors and thermoplastic elastomers in the composition generally ranges from about 10: 1 to 1: 2, preferably about 5: 1 to 1. : 1, and more preferably, approximately between 2: 1 and 1: 1. Suitable elastomeric compositions for use herein form elastomeric members that are elastic without further treatment, and these elastomeric compositions do not include any volatile solvents with a boiling point below 150 ° C. After depositing the elastomeric composition to the substrate, it is possible to use subsequent treatments to improve or reinforce the elasticity and other properties such as strength, modulus and the like of the resulting elastomeric members. Generally, subsequent treatments are used that convert the elastomeric compositions into elastomeric members by methods such as cooling, crosslinking, curing (for example, through chemical, thermal or radiation means), pressure between press rolls and combinations of these.

Typographic Application The present invention also requires the use of a typographic application system comprising a pattern roller, a support roller and an applicator roller. Said typographic application system differs from similar flexographic systems in the patterned roller structure. In the typographic system described herein, the pattern roller has a mostly metallic structure. It is believed that said metal structure is necessary for the heat transfer required to provide cooling of the elastomeric composition described herein. The external surface of the patterned roller comprises a predetermined pattern of raised surface elements. The individual elements can be rectilinear, curvilinear or in any arbitrary way. For example, a regular circular or rectangular shape, or an irregular shape. Adjacent elements may have a space between them or they may be connected and form a continuous pattern. The individual elements may or may not be parallel to each other. Various elements may be placed together to form a component of a finished article (e.g., a disposable diaper). The raised elements can be continuous or discontinuous along the surface of the roller. An example of a continuous pattern is a cross-hatched pattern, with strips in MD and CD that extend over the entire surface of the patterned roller. Another continuous structure would be longitudinal strips extending in a circumferential direction around the entire patterned roller. An example of a discontinuous pattern are spaced horizontal strips that extend in a direction that is, for example, perpendicular to the circumferential direction. In some embodiments, the elements may have a relationship between the largest dimension and the smallest dimension greater than 3, more preferably greater than 10, and even more preferred greater than 25. The largest dimension of the elements is defined, in a aspect, for the greater dimension of an article produced using the process described herein. Generally, this dimension can vary between about 0.1 mm "and about 600 mm.These dimensions are defined by the dimensions of the distal surface of the raised surface elements.Preferably, the walls of the elements are narrowed (i.e. they are narrower in size). the distal surface on the base.) This narrowing can facilitate the cleaning of the patterned roller after long operating times.The walls may also not be narrowed.The illustrative processes by which elevated surface elements can be placed on the patterned roller. ncluyen: mechanical engraving (knurling), chemical engraving, laser engraving and electromechanical engraving The height of the elements is not fundamental as in rotogravure printing, since the material is deposited in the support areas of these elements. high can hinder cleaning if the elastomer, inadvertently da, ends in the spaces between the raised surface elements on the patterned roller. The height of the elements above the base surface of the roller with suitable pattern varies between 0.01 mm and 12 mm, preferably between 0.02 mm and 3.0 mm, and more preferably between 0.05 mm and 2.0 mm. Preferably, the elastomeric composition is transferred to the patterned roller from an applicator roll, in order to achieve a uniform distribution along all the raised elements and to maintain hygiene during the process. This indirect application on the high pattern elements avoids the accumulation of elastomeric composition between the elements, as would occur if thermoplastic resin were applied directly onto the pattern roll by extrusion, spray printing and similar direct application methods. The elastomeric composition can be applied on the applicator roller by immersing the applicator roller in a bath of molten elastomer, slot coating, extrusion coating, spray printing and other methods known in the industry as suitable methods to provide a uniform coating of the material across the width of a roller. If necessary, the CD distribution of the elastomeric composition can be leveled by modification. As is known, a modification unit operation places an obstruction (eg, a blade) in direct contact with or at a fixed distance from a roller or other means of conveying the elastomeric composition to the patterned roller. The obstruction levels out any roughness in the CD distribution of the elastomer by causing the portions to flow from the high points of the distribution to the low points to fill them. Generally, a blade is, in this case, a flexible steel blade. In this process, it may be preferable to heat the blade since the viscosity of the elastomer is high, and also the viscosity increases rapidly because the elastomer is deposited on a surface having a temperature lower than the application temperature of the elastomer. The modification also subjects the elastomer to shear. This can result in a benefit for materials with shear thinning, whose viscosity will decrease during the modification, which will contribute to the leveling process. The support areas of the raised surface elements come into contact slightly with the elastomer layer of the applicator roller. It is important to properly control: i) the thickness of the coating on the applicator roll and ii) the space between the applicator roll and the pattern roller, in order to control the amount of elastomeric composition transferred. If the coating is too thin or the space is too large, the patterned roller will not come into contact with the elastomeric film, and transfer will not occur. On the other hand, if the coating is too thick or the space is too small, the elastomer will be pressed between the bearing areas of the patterned roller. This will result in a poor definition of the pattern of the elastomeric composition transferred and may require the interruption of the line to clean the rolls, due to the accumulation of elastomer between the raised surface elements. After placing the elastomeric composition in the support area of the surface elements of the roller with relatively cold pattern, it is cooled before being transferred to the substrate. This cooling, as well as the resultant increase in viscosity, i.e., the adhesive strength, are important to achieve adhesion failure at the point of transfer to the substrate. It is important to ensure that at least a portion of the surface of the patterned roller has a surface temperature below the application temperature to allow this cooling. The purpose of said cooling is to reduce the temperature of the elastomeric composition to a temperature lower than the order-disorder temperature, in such a way as to increase the adhesive strength of the composition (The order-disorder temperature is the temperature at which a copolymer en bloc performs the transition from an ordered discernible phase to a single non-discernible phase, and is characterized by a substantial reduction of the elastic modulus (G ') as determined by rheological measurements as a function of temperature). For the typical elastomeric compositions used in the present invention, the order-disorder temperature is at least about 140 ° C, sometimes 150 ° C and even 180 ° C or more. As will be appreciated, for high viscosity elastomeric compositions, cooling the deposited elastomer several tens of degrees Celsius may be sufficient to increase the adhesive strength to a point where the failure is adhesion and it is not necessary to cool the composition to the temperature of order-disorder. The ideal is that the surface temperature of the patterned roller is, at least about 25 ° C lower than the temperature of the applicator roller. Preferably, the surface temperature is at least about 50 ° C lower, and more preferably, at least approximately 65 ° C lower. In order to maintain said reduced surface temperature, the patterned roller may have a temperature control system known in the industry to maintain the temperature of the patterned roller at a predetermined temperature lower than the temperature of the application. Optionally, in order to achieve a good release of the elastomer from the high surface elements, the roll may have a permanent or renewable release agent, for example, a chemical compound with fluorine or a silicone, in at least the support areas of the surface elements, and preferably on the entire external surface of said elements. A renewable release agent can be added continuously in the process at a low aggregate level. A suitable renewable release agent is disclosed in U.S. Patent Application Ser. copendiente series 10/151, 562, filed on May 20, 2002. Permanent release coatings for the process components are also known in the industry and usually comprise fluoropolymers or silicone resins. Many substrates are based on polyolefins (polypropylene or polyethylene) and can be damaged (burning or loss of thickness due to calendering) when elastomeric compositions are deposited on them. However, in the process described herein, the chances of damaging the substrate decrease, since the patterned roller cools relatively compared to the temperature of the elastomer placement. In summary, this process allows the transfer of high viscosity elastomers to temperature sensitive substrates, something that the conventional rotogravure printing process can not achieve. By using the process described herein, it is also possible to cool the deposited elastomer much more, even to a temperature below the glass transition temperature of one or more of the polymer blocks comprising the elastomer on the patterned roller, of such that the elastomer has sufficient mechanical strength to assume a solid shape similar to a weft. In this way, it will be possible to detach the solidified elastomer from the patterned roller by applying some tension at the cold end. This solidified elastomer can, if desired, be stretched in the machine direction (eg, by passing it through a nip between the rear roller pair that rotates at a higher speed than the pattern roll); attached to the substrate with an adhesive if necessary, and then allowed to retract to provide a live stretch. It is important to emphasize that live stretching can not be achieved by conventional printing processes, in which more fluid material comes into contact with the substrate. As mentioned above, the elastomeric composition is placed on the pattern roller from an applicator roll, in order to ensure a uniform coating of the raised surface elements. The elastomeric composition is deposited on the external surface of the applicator roller in the molten state from a positioning mechanism that can be selected from the group comprising a slotted coater, a bath, a sprayer and an extruder. However, in both cases, the elastomeric composition is deposited on the applicator roller in a hot condition, then cooled and removed from the roller in a relatively cooler condition. Without being limited by theory, in the case of the typographical application of elastomeric materials, often, when the failure is adhesive, the detachment force necessary to remove the elastomer from the patterned roller is much lower than when the failure is adherent. See Gent and Petrich, Adhesion of Viscoelastic Materials to Riqid Substrates (Adhesion of viscoelastic materials to rigid substrates), Proc. Roy. Soc. A, vol. 310, pgs. 433-448 (1969). Also, when the failure is adhesive (also called interfacial failure by Gent and Petrich), the detachment force required to remove the elastomer from the patterned roller changes very little with increasing viscosity, which is quite beneficial, especially in the case of high viscosity materials. In these cases, practically all of the elastomer is removed from the elements, such that the transfer is practically complete. As used herein "practically complete" or "substantially complete" means no more than about 10%, preferably no more than about 5%, and more preferably no more than about 1% of the composition elastomeric is not transferred to the release substrate from the typographic application device, i.e., the roller. This almost complete transfer is quite favorable. For example, carbonization is minimized, which is a significant problem with the unsaturated elastomers remaining in the dead zones within the rotogravure elements or patterned structures. The residual elastomer test described in the TEST METHODS section below can be used to determine if the transfer is practically complete. The residual elastomer is defined as the weight of the elastomer that remains in the bearing areas of the patterned roller as a percentage of the weight of the elastomer transferred to a substrate length equivalent to the circumference of the patterned roller. The residual elastomer value according to the method is preferably less than 10%, preferably less than 5% and, more preferably, less than 1. It is desirable that the elastomeric composition at least partially penetrate the substrate into at least some locations, so that the resulting intermediate structure is not defaced in subsequent steps of processing or manufacturing or in the finished product. It is preferable that the elastomeric composition penetrate only enough to provide the desired integrity during the subsequent process and the use of the article. For example, if the substrate is a fibrous substrate, it is believed that it is only necessary that the elastomeric composition penetrate about one or two fiber diameters to provide such integrity. In addition, the solid bond within the composite material and / or its preform makes the use of adhesives optional. The degree of penetration can be affected by several factors: the viscosity of the elastomeric composition when in contact with the substrate, the porosity of the substrate and the relative surface tension of the substrate and the elastomeric composition. The typographic application process of the present invention allows partial cooling of the elastomeric composition before it comes into contact with the substrate, which increases its viscosity and decreases the degree of penetration into the substrate. Alternatively, the elastomeric composition can be cooled by blowing air / refrigerated gas on it before or while in contact with the substrate, or the substrate can be cooled, for example, by providing cooling to the backing roller. In another embodiment, the degree of penetration can be improved by passing the substrate / elastomeric compound between a pair of press rolls to increase the penetration of the elastomeric composition into the substrate. The temperature of the press rolls and the applied pressure of the grip point provide greater control of the degree of penetration. In some embodiments, it is possible to vary the amount of elastomeric composition deposited in the different portions of the substrate, and thus vary the properties of local stretching. For example, by changing the patterned roller pattern, the resulting elastomeric members may have different densities in the members (i.e., amounts of elastomeric members per unit area) from one area of the compound to another. In an example of varied quantity, a repeating unit in the patterned roller may correspond to a key dimension of a substrate (eg, the length dimension of an absorbent article that would subsequently be made from the substrate) in such a way as to provide different portions of the substrate with different amounts of elastomeric composition. Moreover, two or more systems can also be used, with different patterns of elevated surface elements or different elastomeric compositions applied to each of them in order to deposit these elastomeric compositions in different portions of the substrate. Additionally, it is also possible to combine different deposit processes. For example, the typographic application may be combined with spray or flexographic printing in order to obtain the desired properties in the resulting elastified composite materials. Figure 1 illustrates schematically one embodiment of a process 100 for manufacturing an elasticized composite material. This process may include a primary operation for making an intermediate structure, which includes the steps of supplying a first substrate by applying an elastomeric composition or material to the first substrate, and, optionally, attaching it to the second substrate. The process 100 may optionally include a secondary operation of gradually stretching the elasticized substrate to provide additional extensibility to the substrate. Figure 1 illustrates in detail the primary operation of the process 100. A substrate 34 is provided by a first supply roller 52 and moved in the machine direction by a typographic application system 105, comprising an applicator roll 53, a roller with pattern 54 and a backing roller 56. The pattern roller 54 deposits an elastomeric composition which, upon transfer to the substrate 34, forms the elastomeric members thereon. The elastomeric composition is sufficiently smooth in the transfer to form a suitably strong bond between the elastomeric composition and the substrate to provide a stretched substrate 35. The elastomeric composition is applied to the patterned roll 54 from an applicator roller 53. A medium Elastomeric composition supply 55 provides a measured amount of elastomeric composition to the applicator roll 53. The delivery means 55 may include means 52 (e.g., a blade) for leveling the elastomeric composition across the CD width of the applicator roll 53. Optionally, a second blade may be used to remove the residual elastomeric composition from the applicator roll 53 for recycling or disposal. As illustrated in Figure 2, the elastomeric composition is deposited on the raised surface elements 258. After transfer, the elastomeric composition is deposited on a substrate 234 as elastic members 260 to form an elasticized substrate 235. Optionally, it can be providing an additional substrata 236 by a second supply roll 262 and combining it with the elasticized substrate 235 by press rolls 264, 266 to place the elastomeric members 260 between the substrates 234, 236 so as to form an intermediate structure 237. If necessary , adhesives can be used to join the two substrates. The elasticized substrate 235 and / or the intermediate structure 237 can be subjected to additional treatments, such as cooling, pressure (eg, passage between a pair of press rolls), crosslinking, curing (eg, by chemical, thermal and chemical methods). radiation), as well as combinations thereof, in order to improve the elastic and mechanical properties of the elastomeric composition deposited thereon and the resulting intermediate structure. A suitable exemplary side operation is shown for use in process 100 as training station 106 in Figure 1 and, in more detail, in Figure 3.

This secondary operation includes a forming station 106 that stretches the intermediate structure 37 (or the elasticised substrate 35) gradually to the point where the substrate is permanently elongated and the intermediate structure 37 becomes an elasticized composite 38. Due to This structural change, the substrate have a reduced resistance to stretching and the elastomeric members have the ability to stretch to the point that permanent elongation allows it. The above process, known as "annular roll pass", is intended to provide additional extensibility in the transverse direction, which is illustrated in Figure 3, where a pair of corrugated rollers intermeshed 108, 109 are used to permanently elongate the substrate as it passes through the grip point 107 to reduce stretch resistance, a desirable gradual stretching operation in the present invention may result. In the same way, the "inter-roller intermeshing" can be used to provide gradual stretching in the machine direction. The resulting compound has a greater degree of stretch in the portions that have undergone such additional process steps. Therefore, such secondary operations provide additional flexibility to achieve stretch properties in localized portions of the elasticized composite. Methods for imparting stretch to an extensible or in some other practically inelastic material by using rollers in the machine direction or cross machine direction and permanently deforming the material are disclosed in U.S. Pat. num. 4,116,892, 4,834,741, 5,143,679, 5,156,793, 5,167,897, 5,422,172 and 5,518,801. In some embodiments, the intermediate structure can be fed into the corrugated rollers meshed with each other at an angle to the machine direction of this secondary operation. As an alternative, the secondary operation may employ a pair of slotted plates that engage each other applied to the intermediate structure under pressure to achieve a gradual stretching of the intermediate structure in localized portions. Substrate can also be imparted to the substrate by throttling, as described in U.S. Pat. num. 5,226,992 and 5,910,224. In this process, the substrate is throttled in one direction by the application of tension, and the elastomer is printed while the substrate is still in a choked state. If necessary, the laminate can be stretched gradually to improve its stretching properties. Another method for imparting extensibility consists of consolidation, as described in U.S. Pat. 5,914,084 and 6,114,263. As described, consolidation involves feeding a non-woven fabric that can be strangled in a first direction, and subjecting the non-woven fabric to a gradual stretching in a direction perpendicular to the first, while applying a tension force to the fabric. non-woven to strangle it, thereby subjecting the non-woven fabric to mechanical stabilization to provide a stabilized, extendable and strangulated non-woven fabric. In addition, the required stretching in a gradual manner can be achieved by combining the stretching techniques detailed herein. As with strangulation, this laminate can stretch gradually to further improve the stretching properties. It is desirable that the extensible substrate does not exhibit significant resistance to stretching when the compound is subjected to the typical stress under conditions of use. The stresses under conditions of use experienced by the composite are due to stretching when the article is placed and / or removed to the user, as well as during the use of the article. The extensible release substrate can be pre-stretched to impart the desired elasticity to the composite. Generally, when the extensible substrate is subjected to pre-tension up to approximately 1.5 times the maximum tension under conditions of use (generally less than about 250% tension), the extensible substrate is permanently elongated so that it does not exhibit tensile strength within the range of tension under use conditions and the elastic properties of the compound are provided practically only with the elastomeric members of the compound. Suitable uses of the elasticized compounds resulting from the processes of the present invention include disposable articles. Illustrative disposable articles include diapers, trainers, adult incontinence articles, sanitary napkins, garments such as gloves, aprons, overalls, socks, etc. These disposable articles may comprise an elasticized region selected from the group comprising a panel, leg fold, waistband, back panel, front panel, side panel and combinations thereof, and these elasticized regions comprise the elastified composites that are manufactured by the process of the present invention.

TEST METHODS Release Force The release strength or adhesion strength test measures the force required to detach an elastomeric composition in the form of a film from a uniform plate of stainless steel at room temperature.

Apparatus Stainless steel plate: Mc Master-Carr (Cleveland, OH), catalog number 8983K62, adjusted to the ASTM A240 standard. The uniform stainless steel plate is made of 304 stainless steel and has a # 2B termination; width = 100 mm, length = 75 mm, thickness = 0.060 Silicone rubber sheet: Mc Master-Carr # 8979K111, high temperature silicone rubber, thickness of 0.08 cm (1/32"), durometer 49A Removable paper: Paul N. Gardner Company, catalog # PC-RP-1K, 22 cm x 28.5 cm (8.63"x 11.25"), ASTM D 4708/2370/1353 Hand roller: A suitable roller can be manufactured as a roller steel 68 mm in diameter, which has a coating of 6 mm thick, hard rubber (65 Shore A) on it. The finished roller has a weight of 2250 grams and a width of 6.35 cm. Mylar film: It is 0.05 mm (2 mils). This Mylar film should be slightly wider and longer than the elastomer in order to ensure that it covers it completely. Stress gauge: A suitable instrument is available from MTS Systems Corp., of Cary, NC, model Alliance RT / 1. Sample holder: Figure 4a illustrates the support 400 used to hold the stainless steel plate during the execution of this method. It is flexed from a 120 mm X 110 mm stainless steel plate to have the following dimensions: Plate width: 110 mm First vertical portion 410-80 mm Horizontal portion 420-25 mm Second vertical portion 430-15 mm Figure 4b shows one of a pair of jaws 440 used to ensure that the stainless steel plate remains in stable contact with the holder 400 throughout the test. The 440 jaws can be conveniently manufactured by flexing 12 mm stainless steel to make it a rectangle 450 of 111 mm width (ie, slightly wider than the 400 support) X 5 mm depth. The jaws are also provided with a mechanism with screws 445 to provide tension against the support 400.

Sample Elastomeric film: The film sample must have exactly the same composition as the elastomeric composition applied when the claimed process is used. The sample width is 50.8 mm (2") by a minimum of 75 mm long by 0.356 mm ± 0.05 mm (14 mils ± 2 mils) thick.These films are prepared as follows: 1) Weigh approximately 12 grams of the elastomeric composition of interest 2) The composition is compression molded by placing the previously weighed material between the pieces of PTFE (Teflon®) film of 0.03 mm (0.010 inches) in size. 3) Place the film between preheated aluminum plates that are inserted into a Carver press model 3853-0 with plates heated to approximately 160 ° C. 4) Heat the material for 3 minutes and press it between the plates applying a pressure of 17 MPa (2500 psi). 5) The formulation is allowed to flow under pressure for 30 seconds. 6) The resulting film is cooled to room temperature. 7) The film is cut into three equal portions. 8) Place each portion between the PTFE films and the preheated aluminum plates and let them heat up to 160 ° C for 1 minute on the Carver press before applying a pressure of 14 MPa (2000 psi). 9) The formulation is allowed to flow under this pressure for 30 seconds. 10) Pressure is removed and the sample rotated 90 °; it is put back into the press and immediately 20.7 MPa (3000 psi) of pressure is applied. 11) Allow the formulation to flow again for 30 seconds. The pressure is removed, the sample is turned over, inserted again in the press and immediately a pressure of 27.6 MPa is applied. (4000 psi). 12) The formulation is allowed to flow again for 30 seconds. 13) The pressure is suppressed and the sample rotated 90 °; it is placed again in the press and immediately 34 MPa (5000 psi) of pressure is applied. 14) Allow the formulation to flow again for 30 seconds.

) After the final pressure, the film is cooled to room temperature. 16) If necessary, two or more sheets of material prepared in accordance with steps 1-15 are laminated by placing the sheets in layers and repeating steps 8-15 to achieve a final sample thickness of 0.36 + 0.05 mm. 17) The films are cut to sizes suitable for sample, in accordance with the test methods described above.

Method 1) The uniform stainless steel plate (SS plate) is placed on a metal support plate. 2) Place the silicone rubber sheet next to the SS plate. This silicone rubber sheet should have approximately the same thickness as the uniform SS plate. 3) Place the sample of the elastomeric film of interest in the uniform plate of SS, so that there is at least 50 mm on the uniform plate of SS and at least 25 mm on the sheet of silicone rubber. 4) The release paper is placed on the elastomeric film and pressure is applied with the hand roller. The hand roller is rolled over the test sample 10 times (1 time = 1 forward movement and 1 return movement). The pressure applied is only the weight of the hand roller.

) The release paper is removed and the test sample is placed on a support SS plate, which is placed on a heating plate maintained at a temperature higher than the order-disordered temperature of the composition. It is necessary to heat the elastomer well above its order-to-disorder temperature to ensure that the elastomer is soft enough to bond with the uniform plate of stainless steel. A temperature of 160 ° C will be sufficient for most of the compositions of interest. 6) Heat the test sample on the heating plate for 10 minutes ± 1 minute. 7) Remove the supporting SS plate together with the test sample and place it on a steel block that is at room temperature. 8) Ten seconds after removal of the heating plate, the Mylar film is placed on the elastomer and pressure is applied with the roller 10 times, as indicated above. 9) Allow the preparation to cool to room temperature air. 10) The uniform plate of SS, together with the elastomer and the Mylar film, is placed in the jaws for proof of resistance to adhesion of the machine for tensile tests. The detachment angle is 180 degrees, and measurements are made at room temperature. 11) The elastomer is removed from the uniform SS plate at 25.4 cm / min (10 inches / minute). The load increases first and then reaches a stable value. 12) This constant release force is recorded and reported in force in grams / cm of elastomer width. 13) A total of at least 3 replications is repeated. 14) The average detachment force and the standard deviation of the recorded measurements are reported.

Residual Elastomer This method is intended to measure the amount of residual elastomer in the pattern roller and uses this data to determine the residual elastomer. In principle, a fluorescent material is incorporated into the elastomer composition of interest, and a curve is created that relates the amount of the composition to the fluorescence. This curve is then used to relate the fluorescence measurements to the amount of thermoplastic elastomer remaining in the raised surface elements.

Materials Fluorescent agent: A suitable fluorescent material is available from UV Process Supply Inc., of Chicago, IL.

Apparatus Any suitable apparatus capable of providing appropriate lighting and measuring the intensity of the emitted light may be used. The device should be as compact as possible within the limitations of the measurement requirements. Fluorimeter: It must be able to receive and measure the intensity of the light emitted by the fluorescent material. The fluorimeter should include an appropriate optical filter adjusted for the wavelength characteristic of the light emitted by the fluorescent agent. Exciter: Must be able to provide light at the characteristic wavelength that is most efficient for the transfer of energy to the fluorescent agent. The exciter should include an optical filter to define the wavelength of the light used to illuminate the fluorescent agent.

Sample Elastomer: An elastomer sample is taken that is at least three times the estimated volume of the elastomer delivery apparatus of the application system being evaluated.

Determination of fluorescent agent concentration 1. Prepare a 0.01% solution of the elastomer in a suitable solvent. 2. Prepare a solution of a known concentration of the fluorescent agent in the same solvent. 3. Aliquots of the fluorescent agent solution are added to the aliquots of the elastomer solution to provide mixed solutions equivalent to 0.01% elastomer solutions that have had a fluorescent agent at concentrations of 0.1%, 0.5%, 1%, 2% and 5% added to them. 4. Calibrate the fluorimeter and exciter according to the manufacturer's instructions. 5. The intensity of the light emitted from each of the mixed solutions is determined (lo rO ß) - 6. A fluorescent agent concentration is selected that provides an acceptable signal to the noise ratio.

Preparation of the elastomer The elastomer and the fluorescent agent combine to completely disperse the fluorescent agent in the elastomer at the lowest concentration necessary to achieve an acceptable signal for the noise ratio, as determined from the intensity / concentration curve . GLS Corporation of Mc Henry, IL is a manufacturer of suitable compounds for this operation.

Preparation of the standard fluorescence curve 1. Portions of the composite elastomer are dissolved using the concentration of fluorescent agent, as previously determined in a suitable solvent, in concentrations of 0.01%, 0.05%, 0.1%, 0.5% and 1%. 2. The intensity of the fluorescence of each sample is measured and recorded using the fluorimeter. 3. Steps 1 and 2 are repeated for two additional sets of samples. 4. A curve of the concentration versus the average intensity of each concentration is plotted.

Determination of the residual elastomer 1. The non-composite elastomers are removed from the elastomer delivery apparatus. 2. The elastomer supply apparatus is filled with the composite elastomer. 3. The typographic application system is put into operation. 4. The typographic adhesive application system is operated under production operating conditions until at least two volumes of the composite elastomer supply system have been consumed. Once steps 1-4 are finished and before the rest of the composite elastomer is consumed, the following measurements are carried out while the system is operating under production operating conditions. 5. The applicator roller is retracted as to prevent transfer of the elastomer from the applicator roller to the pattern roller. 6. The process is still operated under production operating conditions with the applicator roll retracted for at least 20 revolutions of the patterned roller (approximately 10-30 seconds). 7. An interruption of the controlled line is carried out. 8. The product produced during the period is collected in order to maintain the product sequence. 9. A pattern is selected for further evaluation. As used herein, a "pattern" is a portion of the elastomeric composition that has been deposited on the substrate surface of one plus raised pattern elements, wherein the elements are located on a specific portion of the pattern roll. 10. From the product collected, the first pattern produced is identified where the elastomer transferred to it is visibly reduced. This pattern is indicative of the point in the process flow where the applicator roll retracted. 11. Collect 20 individual patterns produced after the first pattern with a visible reduction of the transferred elastomer, taking care to keep the patterns in the order of production. 12. Collect 20 individual products produced before the first pattern with a visible reduction of the transferred elastomer, taking care to keep the products in the order of production. 13. The numbering of samples 1 to 41 goes from sample number 1, as the sample produced with the longest duration of time before the applicator roll is retracted, to sample number 41, as the sample produced with the longest duration of time after retracted the applicator roller. As will be appreciated, sample 21 is the sample visually identified in step 8. 14. Samples 1-25 are extracted using a suitable solvent.

. The intensity of the fluorescence of the extracts of each sample is measured. If necessary, the extracts can be concentrated using known methods to increase the measured intensity. 16. Using the samples 1-20, the limits of the process capacity (mean intensity ± 3 standard deviations) of the application process for the selected pattern are determined. 17. The intensity of the sample 21 is compared with the limits of the capacity of the process. If the intensity of the sample 21 is within the limits of the process capacity, proceed to step 16. Otherwise, it is retraced (ie, to sample 1) through the samples to determine the first sample that it has an intensity within the limits of the capacity of the process. 18. For sample 21 (or an alternative start point, as determined in step 15) and the next 5 samples in the sequence, the elastomer aggregate (aggregate weight ^ - aggregate weight26) is determined by applying the standard curve developed using the method described above. 26 Aggregate weight 19. Residual percentage = - b x 100 Aggregate weight 21 20. Repeat steps 5-15 three more times. 21. The average residual elastomer percentage, residual elastomer percentage values and all the data used to calculate them are reported.

Example 1 This example compares the properties of commercially available adhesives (elastomeric and non-elastomeric), a thermoplastic elastomer and illustrative non-adhesive elastomeric compositions.

'• Bostik Findley elastomeric adhesive from Wauwatosa, Wl 2- Bostik Findley adhesive 3- Styrene / isoprene / styrene block copolymer available from Dexco Polymers LP, Houston, TX 4- Vector 8508a 20% low molecular weight thermoplastic elastomer b 50% Drakeol 600c 25% Photoinitiator Md 5% a: Copolymer block styrene from Dexco Company, Houston, TX b: Experimental styrene-isoprene-styrene block copolymer from Dexco c: Mineral oil from Pennzoil Co., Penrenco Div., Karns City, PA d: National Starch and Chemicals experimental sample from Bridgewater, NJ 5- Septon 4033a 40% SHF 401 b 40% Dioctyldodecylterephthalate oligomer 20% a: Copolymer in styrene block from Kuraray America, Inc. of New York, NY b: Synthetic poly-olefin oil from ExxonMobile Chemical Co., Houston, TX.

All documents cited in the Detailed Description of the Invention are incorporated, in the relevant part, as reference herein. The mention of any document should not be construed as an admission that it corresponds to a prior industry with respect to the present invention. Although particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the industry that various other changes and modifications can be made without departing from the spirit and scope of the invention. It has been intended, therefore, to cover in the appended claims all changes and modifications that are within the scope of the invention.

Claims (11)

1. A process for manufacturing an elasticized composite material; the method comprises the steps of: a) Providing a first substrate, the substrate moves in a machine direction, wherein the substrate has a first and a second opposing surfaces; b) provide a typographic adhesive application system, the typographic adhesive application system comprises a patterned roller and an applicator roller, each of the rollers has an outer surface with a surface temperature of the roller, a portion of the outer surface of the roller with pattern comprises a predetermined pattern of raised surface elements; c) depositing a molten non-adhesive elastomeric composition on the outer surface of the applicator roll, the composition having an application temperature; the application temperature is higher than the surface temperature of the patterned roller and a peel force of less than about 3 N / cm; d) transferring a portion of the applicator roller composition to a distal surface of the raised elements, such that the surface of the raised surface elements is covered, wherein the composition exhibits sticky faults such that a portion of the composition it also remains in the applicator roller; and e) cooling the transferred portion to a temperature between the application temperature and the surface temperature of the patterned roller, which causes an increase in the adhesive strength so that the adhesion strength is greater than the peel strength; and f) causing the first surface of the substrate to come into contact with the raised elements with the coated surface characterized in that the elastomeric composition of the distal surface of the raised surface elements is substantially completely transferred to the first surface in step f. The method according to claim 1, further characterized in that the following steps are carried out after step e and before step f: i) applying tension to the elastomeric elements to detach the elements from the patterned roller; and ii) stretching the elastomeric elements in the machine direction. 3. The method according to claim 1 or 2, further characterized in that the outer surface of the patterned roller has a temperature that is at least 5 ° C lower than at least one surface temperature of the applicator roll and an application temperature. . 4. The method according to any of the preceding claims, further characterized in that the composition is deposited using a delivery means selected from the group comprising a slotted coater, a bath, a sprayer and an extruder. 5. The method according to any of the preceding claims, further characterized in that a second substrate comes into contact with the elastomeric composition after the transfer of the composition. The method according to any of the preceding claims, further characterized in that the substrate is gradually stretched after the transfer of the composition in such a manner as to permanently elongate at least a portion thereof. The method according to any one of the preceding claims, further characterized in that the elastomeric composition comprises thermoplastic elastomers and processing oils, preferably comprising from 1% to 70% of the processing oil, and which is practically free of water promoting agents. stickiness. The method according to any of the preceding claims, further characterized in that at least a portion of the components of the elastomeric composition comprises crosslinkable materials. The method according to any of the preceding claims, further characterized in that the elastomeric composition also comprises from about 1% to about 50% by weight of a non-elastomeric thermoplastic polymer. 10. The method according to any of the preceding claims, further characterized in that the elastomeric composition has a vitreous transition temperature and in that the elastomeric composition is cooled to a temperature lower than the vitreous transition temperature before the elements detach from the patterned roller. The method according to any of the preceding claims, further characterized in that the substrate is stretched in the machine direction so as to throttle the substrate in a direction transverse to the machine prior to the transfer of the composition.