Elastomer laminate having a control layer and method thereof

Abstract

The present disclosure relates to absorbent articles incorporating elastomeric laminates that can be formed by stretching and bonding elastic strands to either or both of a first and a second substrate using an adhesive. The elastic strands can be supplied from a wound supply, such as a beam of elastic strands. The beam can be treated with a control layer to reduce blocking when multiple elastic strands are on the beam and provide reliable unwinding. Once the elastic strands are adhesively bonded to the first and second substrates to form the elastomeric laminate, the control layer can be absorbed by the adhesive.

Description

[Technical Field]

[0001] This disclosure relates to absorbent articles having elastomer laminates, and more specifically to adhesives, control layers, and elastic strands for elastomer laminates. [Background technology]

[0002] Various types of articles, such as diapers and other absorbent articles, can be assembled by adding components to a continuous web of material along an assembly line, and / or by processing the continuous web of material in other ways. For example, in some processes, a web of material is combined with another web of material. In other examples, individual components made from a web of material are combined with a web of material, and then these are combined with another web of material. In some examples, individual components made from one or more webs of material are combined with other individual components made from other webs of material. The webs and components of material used to manufacture diapers may include a backsheet, a topsheet, leg cuffs, a waistband, absorbent core components, front and / or rear ear sections, fastening components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, stretch side panels, and waist elastics. Once the desired component parts are assembled, the advancing web and component parts are subjected to a final knife cut to separate the web into individual diapers or other absorbent articles.

[0003] Some absorbent articles have components including an elastomer laminate. Such an elastomer laminate may include an elastic material bonded to one or more nonwoven fabrics. The elastic material may include an elastic film and / or elastic strands. In some laminates, when multiple strands are stretched, the elastic strands bond together to form a nonwoven fabric, and as a result, when the elastic strands relax, the nonwoven fabric forms folds between the points where it joins the elastic strands, thereby forming a corrugated shape. The resulting elastomer laminate is stretchable to the extent that the elastic strands can be stretched by the corrugation.

[0004] In some assembly processes, stretched elastic strands may be advanced in the mechanical direction and bonded between two advancing substrates, with the stretched elastic strands spaced apart transversely. Some assembly processes also consist of several elastic strands spaced very close together transversely. In some configurations, the close transverse spacing between elastic strands can be achieved by drawing the elastic strands from windings stacked transversely on a beam. For example, various fiber manufacturers can utilize beam elastic materials and associated handling equipment, such as those available from Karl Mayer Corporation.

[0005] However, problems can arise in the manufacturing process when using elastic strands laminated on a beam. For example, elastic strands on a beam are prone to blocking when drawn from the beam due to bridging between strands caused by the high compression of the beam over a considerable storage life. To prevent blocking in elastic strands, they can be treated with silicone oil or other types of spin finish. While applying a spin finish to the beam can reduce the likelihood of blocking, spin finish can have undesirable effects on the manufacturing process. For example, when elastic strands are formed in an elastomer laminate and an adhesive is used to bond the strands to the nonwoven layer, spin finish can negatively affect the effectiveness of the adhesive. A relatively large amount of adhesive may be required to achieve the desired level of adhesion. Using a large amount of adhesive is undesirable because it increases the cost of the material and results in a rigid laminate that does not have the desired appearance or performance for incorporation into absorbent articles. [Overview of the project] [Problems that the invention aims to solve]

[0006] As a result, it would be beneficial to provide a method and apparatus for producing an elastomer laminate from a beam of elastic strands that utilize an anti-blocking agent but can be easily adhered to a nonwoven fabric layer. Furthermore, it would be beneficial to form disposable absorbent articles incorporating the elastomer laminate. [Means for solving the problem]

[0007] In a first embodiment, a disposable absorbent article in the form of a diaper or absorbent pants may comprise a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent core disposed between the top sheet and the back sheet. The disposable absorbent article may comprise an elastomer laminate. The elastomer laminate may comprise a plurality of transversely spaced elastic strands bonded to a nonwoven web material by an adhesive. The elastic strands may comprise a strand polymer (e.g., segmented polyurethane), the strand polymer having a strength of about 18 MPa 1 / 2 ~Approx. 18.5MPa 1 / 2 The adhesive has solubility parameters within the range of [value]. The adhesive may contain an adhesive polymer, and the adhesive polymer has a solubility of approximately 16 MPa. 1 / 2 ~Approx. 17.5MPa 1 / 2 It has solubility parameters within the range. The elastic strand can be supplied from the elastic strand winding supply unit. The elastic strand winding supply unit operates at approximately 15.5 MPa. 1 / 2 ~Approx. 16.5MPa 1 / 2 It may include a control layer having a solubility parameter within a certain range and a number-average molecular weight in the range of approximately 0.6 kg / mol to approximately 1.5 kg / mol.

[0008] In another embodiment, a disposable absorbent article in the form of a diaper or absorbent pants may comprise an elastomer laminate. The elastomer laminate comprises a plurality of transversely spaced elastic strands bonded to at least a first layer of nonwoven web material by an adhesive. The elastic strands comprise a first spandex-based block copolymer. The block copolymer may comprise rubber blocks and rigid blocks. The rubber blocks may be selected from the group consisting of polyethers, polyesters, and combinations thereof. The adhesive may comprise an adhesive polymer, which may comprise a second styrene-based block copolymer. In some implementations, the adhesive may comprise a tackifier. The second block copolymer may comprise rubber blocks, which may be selected from the group consisting of polyisoprene, polybutadiene, polyisoprene-co-butadiene, and their hydrogenated variants. A control layer may be dispersed at least partially from the elastic strands into the adhesive.

[0009] In yet another embodiment, a disposable absorbent article in the form of a diaper or absorbent pants may comprise an elastomer laminate. The elastomer laminate may comprise a plurality of transversely spaced elastic strands bonded to at least a first layer of nonwoven web material by an adhesive. The elastic strands may comprise a first spandex-based block copolymer. The block copolymer may comprise rubber blocks and rigid blocks, the rubber blocks may be selected from the group consisting of polyethers, polyesters, and combinations thereof. The adhesive may comprise an adhesive polymer, the adhesive polymer may comprise a second styrene-based block copolymer. The second block copolymer may comprise rubber blocks which may be selected from the group consisting of polyisoprene, polybutadiene, polyisoprene-co-butadiene, and their hydrogenated variants. The elastomer laminate may comprise soap.

[0010] In another embodiment, a process for producing an elastomer laminate may include unwinding elastomer strands coated with a control layer, the control layer may contain mineral oil. The process may further include bonding the elastomer strands between a first substrate layer and a second substrate layer to form an elastomer laminate. The elastomer strands may have an average strand spacing of about 0.25 mm to about 4 mm, and the average Dtex of the elastomer strands may be about 10 to about 500.

[0011] In yet another embodiment, a method for assembling an elastomer laminate may include providing a first substrate and a second substrate. The method may further include advancing elastic strands in a mechanical direction. The elastic strands may be separated from each other in a transverse direction. The method may further include applying an adhesive to at least one of the elastic strands, the first substrate, and the second substrate, and combining the elastic strands with the first and second substrates to form an elastomer laminate. The method may further include dispersing a control layer from the elastic strands into the adhesive. The control layer may contain mineral oil. [Brief explanation of the drawing]

[0012] [Figure 1A] It is a front-side perspective view of a diaper pant. [Figure 1B] It is a rear-side perspective view of a diaper pant. [Figure 2] It is a partially cut-away plan view of the diaper pant shown in FIGS. 1A and 1B in a flat and non-shrunk state. [Figure 3A] It is a cross-sectional view of the diaper pant of FIG. 2 along line 3A-3A. [Figure 3B] It is a cross-sectional view of the diaper pant of FIG. 2 along line 3B-3B. [Figure 4] It is a schematic side view of a processing apparatus adapted to manufacture an elastomeric laminate including a first plurality of elastic strands positioned between a first substrate and a second substrate. [Figure 5] It is a view of the processing apparatus of FIG. 4 along line 5-5. [Figure 6] An example of an empty beam is shown. [Figure 7] It schematically shows the adhesion of elastic strands to a first substrate. [Figure 8] It schematically shows the time-dependent interaction of a plurality of elastic strands, an adhesive, and a control layer during the manufacture of an elastomeric laminate. [Figure 9] It shows a laminate creep test. [Figure 10] It shows a laminate creep test. [Figure 11] It shows a laminate creep test.

Mode for Carrying Out the Invention

[0013] The following glossary may be useful in understanding the present disclosure. In this specification, “absorbent article” is used to refer to consumer products whose primary function is to absorb and retain soil and excrement. In this specification, “diaper” is used to refer to absorbent articles typically worn around the lower torso by infants and persons with incontinence. In this specification, the term “disposable” is used to describe absorbent articles that are not generally intended to be washed or otherwise recycled or reused as absorbent articles (for example, they are intended to be discarded after one use and may be configured for recycling, composting, or other environmentally friendly disposal).

[0014] "Elastic," "elastomer," or "elastomer-like" refers to a material that exhibits elastic properties, including any material that, when a force is applied to its initial relaxed length, can be stretched or elongated to an elongation length exceeding 10% of its initial length, and that substantially returns to approximately its initial length after the applied force is released.

[0015] As used herein, the term “joined” includes configurations in which one element is directly attached to another element by directly adhering it to that element, as well as configurations in which one element is indirectly attached to another element by adhering it to an intermediate member(s) and then adhering that intermediate member(s) to another element.

[0016] "Longitudinal direction" refers to the direction substantially perpendicular to the longitudinal direction when an absorbent article is laid flat and in an uncontracted state, from one waist edge of the article to the opposite waist edge in the longitudinal direction, or from the waist edge to the bottom of the crotch, i.e., the fold line of an article folded in half. Directions within 45 degrees of the longitudinal direction are considered "longitudinal direction". "Transverse direction" refers to the direction extending from one longitudinal side edge of the article to the opposite longitudinal side edge in the transverse direction, and generally perpendicular to the longitudinal direction. Directions within 45 degrees of the transverse direction are considered "transverse direction".

[0017] In this specification, the term “substrate” is used primarily to describe a material that is two-dimensional (i.e., in the XY plane) and whose thickness (in the Z direction) is relatively small (i.e., less than 1 / 10) compared to its length (in the X direction) and width (in the Y direction). Non-limiting examples of substrates include webs, layers (one or more) or fibrous materials, nonwoven fabrics, polymer films or films and foils such as metal foils. These materials may be used individually or may consist of two or more layers laminated together. For this reason, a web is a substrate.

[0018] In this specification, the term “nonwoven fabric” refers to a material made from continuous (long) filaments (fibers) and / or discontinuous (short) filaments (fibers) by processes such as spunbonding, meltblowing, and carding. Nonwoven fabrics do not have a woven or knitted filament pattern.

[0019] In this specification, the term “machine direction” (MD) refers to the direction of material flow through a process. In addition, the relative arrangement and movement of materials can be described as flowing in the machine direction, from upstream to downstream of a process.

[0020] In this specification, the term “transverse direction” (CD) refers to a direction approximately perpendicular to the machine direction.

[0021] The term “tape-type diaper” (also called “open-type diaper”) refers to a disposable absorbent article having an initial front lumbar region and an initial rear lumbar region that are not fastened, pre-fastened, or joined to each other before being applied to the wearer or during packaging. Tape-type diapers may be folded along the transverse centerline with the interior of one lumbar region in surface-to-surface contact with the interior of the opposite lumbar region, without fastening or joining the lumbar regions together. Examples of tape-type diapers of various suitable configurations are given in U.S. Patent Nos. 5,167,897, 5,360,420, 5,599,335, 5,643,588, 5,674,216, 5,702,551, 5,968,025, 6,107,537, 6,118,041, 6,153,209, and 6,410,1 This is disclosed in Patent No. 29, No. 6,426,444, No. 6,586,652, No. 6,627,787, No. 6,617,016, No. 6,825,393, and No. 6,861,571, as well as in U.S. Patent Publication No. 2013 / 0072887(A1), No. 2013 / 0211356(A1), and No. 2013 / 0306226(A1).

[0022] In this specification, the term “pants” (also referred to as “training pants,” “pre-closed diapers,” “diaper pants,” “pants-type diapers,” and “pull-on diapers”) refers to disposable absorbent articles designed for infant or adult wearers, having continuous waist openings and continuous leg openings on the outer edges. Pants may be configured to have continuous or closed waist openings and at least one continuous closed leg opening before the article is applied to the wearer. Pants may be pre-formed or pre-fastened by a variety of techniques, including but not limited to joining parts of the article together using any re-fastening and / or permanent closing members (e.g., seams, thermal ties, pressure ties, adhesives, cohesive bonds, mechanical fasteners, etc.). Pants may be pre-formed at any location along the outer periphery of the article within the waist region (e.g., side fastening or sewing, front waist fastening or sewing, back waist fastening or sewing). Examples of diaper pants in various configurations are given in U.S. Patent Nos. 4,940,464, 5,092,861, 5,246,433, 5,569,234, 5,897,545, 5,957,908, 6,120,487, 6,120,489, 7,569,039, and U.S. Patent Application Publication No. 2003 / 0233082(A1), This information is disclosed in issues 2005 / 0107764(A1), 2012 / 0061016(A1), 2012 / 0061015(A1), 2013 / 0255861(A1), 2013 / 0255862(A1), 2013 / 0255863(A1), 2013 / 0255864(A1), and 2013 / 0255865(A1).

[0023] "Decitex," also known as "Dtex," is a unit of measurement used in the textile industry to measure yarn or filament. 1 decitex = 1 gram per 10,000 meters. In other words, if 10,000 linear meters of loose yarn or filament weigh 500 grams, then that yarn or filament has 500 decitex.

[0024] The present disclosure relates to disposable absorbent articles, particularly disposable absorbent articles incorporating an elastomeric laminate, and a process for making the elastomeric laminate. The disposable absorbent article according to the present disclosure can be in the form of a diaper or absorbent pants and can include a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core disposed between the topsheet and the backsheet. The disposable absorbent article can also include an elastomeric laminate comprising a plurality of laterally spaced elastic strands joined to a nonwoven web material by an adhesive. The elastic strands can comprise, for example, a strand polymer having a solubility parameter within the range of about 18 MPa 1 / 2 to about 18.5 MPa 1 / 2 The adhesive can comprise, for example, an adhesive polymer (such as a styrene block copolymer or a polyolefin-based polymer, or a blend thereof) having a solubility parameter within the range of about 16 MPa 1 / 2 to about 17.5 MPa 1 / 2 The adhesive of the present disclosure may or may not include a tackifier. Further, the adhesive of the present disclosure can include less than 20% tackifier, less than 15% tackifier, less than 10%, or less than 5% tackifier. The elastic strands can be supplied from a wound supply of elastic strands, such as a beam, spool, or other source. The wound supply of elastic strands can include, for example, a control layer having a solubility parameter within the range of about 15.5 MPa 1 / 2 to about 16.5 MPa 1 / 2 and a number average molecular weight within the range of about 0.6 kg / mol to about 1.5 kg / mol. For additional information regarding the determination of solubility parameters according to the present disclosure, refer to "CRC Handbook of Chemistry and Physics, 97th Edition", CRC Press, Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742. For additional information regarding the determination of number average molecular weight (using polystyrene as the calibration standard and based on a refractive index (RI) detector) according to the present disclosure, refer to "Introduction to Polymers, 2nd See "Edition," RJ Young and PA Lovell, pages 211–221.

[0025] The beam may contain approximately 40 to 1000 elastic strands, or approximately 100 to 750 elastic strands, or approximately 200 to 600 elastic strands, or approximately 300 to 500 elastic strands. While this disclosure highlights the advantages of using a control layer with a beam containing many fine (less than approximately 500 dtex) elastic strands, it should be understood that it may also be desirable to use a control layer on a spool that may contain a single elastic strand. Furthermore, it may be desirable to use a control layer on elastic strands of conventional size (greater than approximately 500 dtex).

[0026] Furthermore, the elastomer laminates according to this disclosure may include a plurality of transversely spaced elastic strands containing spandex polymers. Commercially available spandex strands are also known as Lycra, Creora, Roica, or Dorlastan. Spandex polymers are sometimes called elastane, segmented polyurethane copolymers, or segmented polyurea copolymers. Spandex polymers contain rubber blocks and rigid blocks. These blocks are connected by urethane or urea chemical bonds. Typical rubber blocks include polyethers such as polytetramethylene oxide or polyesters such as polycaprolactone. Rigid blocks may include diisocyanates such as diphenylmethane 4,4'-diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI). These diisocyanates can be optionally bonded together using diols such as butanediol or diamines such as hydrazine or ethylenediamine. It is understood that a variety of rubber blocks, rigid blocks, and coupling agents may be intended for use. For example, the rubber block polymer may contain polyesters such as polyethylene adipate, polypropylene adipate, and polybutylene adipate, poly-1,5-pentanediol, 1,6-hexanediol, or 1,10-decanediol, or polyethers such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol. Similarly, the rigid block may contain diphenylmethane 4,4'-diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylenedicyclohexyl diisocyanate (hydrogenated MDI (HMDI)), or isophorone diisocyanate (IPDI). Likewise, any coupling agent for the rigid block may contain diamines (such as hydrazine and ethylenediamine) or diols (such as butanediol, 1,5-pentanediol, or 1,6-hexanediol).

[0027] The adhesive for the elastomer laminate may include an adhesive polymer containing a styrene-based block copolymer. The block copolymer may include rubber blocks selected from the group consisting of polyisoprene, polybutadiene, polyisoprene-co-butadiene, and their hydrogenated variants. In some embodiments, the elastomer laminate may also contain soap.

[0028] Furthermore, the adhesive polymers of the present disclosure may be styrene block copolymers or polyolefin polymers, or blends thereof. The styrene block copolymers of the present disclosure may include styrene-butadiene (SB), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-isoprene (SI), styrene-isoprene-butadiene-styrene (SIBS), styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-butylene (SEB), styrene-ethylenepropylene-styrene (SEPS), and styrene-ethylenepropylene (SEP), and styrene-ethylene-ethylene-propylene-styrene (SEEPS or hydrogenated SIBS). The styrene block copolymers of the present disclosure may have a general composition ABA, or a mixture of AB and ABA, where the polymer terminal block A is styrene, and the polymer intermediate block B is derived from isoprene, butadiene, or isobutylene, or mixtures thereof, which can be partially or substantially hydrogenated. Furthermore, the copolymers may be linear or branched. In particular, a styrene content exceeding 40% in the styrene block copolymer can reinforce creep resistance, while a melt flow index exceeding 33 can enable a desirable viscosity. The polyolefin polymers of this disclosure may be propylene polymers, which are copolymers of propylene homopolymers and one or more other comonomers (e.g., ethylene, butene, pentene, octene, etc.). The propylene polymers may be entirely olefinic, i.e., they may not contain any functional groups. The propylene polymers may contain more than 75% by weight of propylene, or even more than 80% by weight of propylene. Furthermore, the propylene polymers may contain 10-20 mol% or 13-16 mol% of comonomers. The propylene polymers may have a polydispersity (Mw / Mn) of less than about 5, less than about 3, or even about 2. Useful propylene polymers may have a density of about 0.90 or less, about 0.89 or less, or even about 0.88 or less. Useful propylene polymers include those catalyzed with single-site (e.g., metallocene) catalysts.Furthermore, polyolefin polymers were prepared in the presence of metallocene as a catalyst, with ethylene and C3-C3. 20 It can be used as a copolymer with α-olefin.

[0029] According to this disclosure, a process for producing an elastomer laminate may include unwinding elastomer strands coated with a control layer. The control layer may include, for example, mineral oil, paraffinic mineral oil, white mineral oil, synthetic oil, polyisoprene, and / or polybutadiene. The process may include bonding the elastomer strands between a first substrate layer and a second substrate layer to form an elastomer laminate, the elastomer strands having, for example, an average strand spacing of about 0.25 mm to about 4 mm, or about 0.25 mm to about 3 mm, or about 0.5 mm to about 3 mm, or about 0.25 mm to about 2 mm, or about 0.5 mm to about 2 mm. Furthermore, the average Dtex of the elastomer strands may be in the range of about 10 to about 500, or about 10 to about 400, or about 10 to about 300. The relative amount of the control layer used on the elastomer strand can vary, but in some embodiments, the control layer is less than about 5% by weight, less than 3% by weight, or less than 2% by weight of the elastomer strand.

[0030] Furthermore, according to this disclosure, a method for assembling an elastomer laminate may include providing a first substrate and a second substrate, and advancing elastic strands in a mechanical direction. The elastic strands may be separated from each other in the transverse direction. The method may also include applying an adhesive to at least one of the elastic strands, the first substrate, and the second substrate, and combining the elastic strands with the first and second substrates to form an elastomer laminate. The method may also include dispersing a control layer containing mineral oil from the elastic strands into the adhesive.

[0031] As previously stated, elastomer laminates produced according to the processes and apparatus discussed herein can be used to construct various types of components used in the manufacture of different types of absorbent articles, such as diaper pants and tape-style diapers. To help provide further context for the subsequent discussion of process embodiments, an overview of absorbent articles in the form of diapers, including components such as elastomer laminates that can be produced using the methods and apparatus disclosed herein, is provided below.

[0032] Figures 1A, 1B, and 2 show an example of a diaper pants 100 which may include components constructed from elastomer laminates assembled according to the apparatus and methods disclosed herein. Specifically, Figures 1A and 1B show perspective views of the diaper pants 100 in a pre-fastened configuration, and Figure 2 shows a plan view of the diaper pants 100 with the portion of the diaper facing away from the wearer oriented towards the viewer. The diaper pants 100 includes a chassis 102 and an annular elastic belt 104. As will be discussed in more detail below, a first elastic belt 106 and a second elastic belt 108 may be joined together to form the annular elastic belt 104.

[0033] Referring again to Figure 2, the diaper pants 100 and chassis 102 each include a first waist region 116, a second waist region 118, and a crotch region 119 positioned between the first and second waist regions. The first waist region 116 may be configured as an anterior waist region, and the second waist region 118 may be configured as a posterior waist region. The diaper 100 may also include an anterior waist edge 121 extending laterally in the anterior waist region 116, and a posterior waist edge 122 facing longitudinally and extending laterally in the posterior waist region 118. To provide a reference system for this study, the diaper 100 and chassis 102 in Figure 2 are shown to have a longitudinal axis 124 and a lateral axis 126. In some embodiments, the longitudinal axis 124 may extend through the front waist edge 121 and the rear waist edge 122. The transverse axis 126 may extend through the first longitudinal direction or the right edge 128 of the chassis 102 and through the midpoint of the second longitudinal direction or the left edge 130.

[0034] As shown in Figures 1A, 1B, and 2, the diaper pants 100 may include an inner, body-facing surface 132 and an outer, clothing-facing surface 134. The chassis 102 may include a backsheet 136 and a topsheet 138. The chassis 102 may also include an absorbent assembly 140, which includes an absorbent core 142 disposed between a portion of the topsheet 138 and the backsheet 136. As will be described in more detail below, the diaper 100 may also include other features such as leg elastic members and / or leg cuffs to enhance the fit around the wearer's legs.

[0035] As shown in Figure 2, the periphery of the chassis 102 may be defined by a first longitudinal side edge 128, a second longitudinal side edge 130, a first laterally extending end edge 144 located within the first waist region 116, and a second laterally extending end edge 146 located within the second waist region 118. Both the side edges 128 and 130 extend longitudinally between the first end edge 144 and the second end edge 146. As shown in Figure 2, the laterally extending end edges 144 and 146 may be located longitudinally inward from the front waist edge 121 that extends laterally in the front waist region 116, and longitudinally inward from the rear waist edge 122 that extends laterally in the rear waist region 118. When the diaper pants 100 are worn on the lower torso of the wearer, the front waist edge 121 and the rear waist edge 122 may surround the wearer's waist. At the same time, the side edges 128 and 130 may surround at least a portion of the wearer's legs. The crotch area 119 may be positioned generally between the wearer's legs, and the absorbent core 142 extends from the front waist area 116 through the crotch area 119 to the rear waist area 118.

[0036] As described above, the diaper pants 100 may include a backsheet 136. The backsheet 136 may also define the outer surface 134 of the chassis 102. The backsheet 136 may also include a woven or nonwoven material, a polymer film such as a polyethylene or polypropylene thermoplastic film, and / or a multilayer or composite material including a film and a nonwoven material. The backsheet may also include an elastomer film. An example backsheet 136 may be a polyethylene film with a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mil). Furthermore, the backsheet 136 can prevent waste from passing through the backsheet 136 while allowing vapor to escape from the absorbent core (i.e., the backsheet is breathable).

[0037] As described above, the diaper pants 100 may also include a top sheet 138. The top sheet 138 may also define all or part of the inner surface 132 of the chassis 102. The top sheet 138 may be liquid permeable, allowing liquids (e.g., menstrual blood, urine and / or liquid feces) to penetrate through its thickness. The top sheet 138 may be made from a wide range of materials, such as woven and nonwoven materials, perforated or hydroformed thermoplastic films, perforated nonwovens, porous foams, mesh foams, mesh thermoplastic films, and thermoplastic scrim. The woven or nonwoven materials may be made from a wide range of materials, such as natural fibers like wood fibers or cotton fibers, synthetic fibers like polyester, polypropylene or polyethylene fibers, or combinations thereof. If the top sheet 138 contains fibers, the fibers may be treated by spunbonding, carding, wet processes, meltblown processes, water entanglement, or other methods known in the art. The top sheet 138 may be selected from bulky nonwoven fabric top sheets, perforated film top sheets, and perforated nonwoven fabric top sheets. Examples of perforated films include those described in U.S. Patents No. 5,628,097, No. 5,916,661, No. 6,545,197, and No. 6,107,539.

[0038] As described above, the diaper pants 100 may also include an absorbent assembly 140 joined to the chassis 102. As shown in Figure 2, the absorbent assembly 140 may have a front edge 148 extending laterally within the front waist region 116, and a rear edge 150 extending laterally and facing longitudinally within the rear waist region 118. The absorbent assembly may have a right edge 152 extending longitudinally, and a left edge 154 extending longitudinally and facing laterally, and both the side edges 152 and 154 of the absorbent assembly may extend longitudinally between the front edge 148 and the rear edge 150. The absorbent assembly 140 may additionally include one or more absorbent cores 142 or absorbent core layers. The absorbent core 142 may be at least partially disposed between the top sheet 138 and the back sheet 136, and may be formed in various sizes and shapes to suit the diaper. Exemplary absorbent structures for use as the absorbent core of this disclosure are described in U.S. Patents 4,610,678, 4,673,402, 4,888,231, and 4,834,735.

[0039] Some embodiments of absorbent cores may comprise a fluid storage core containing a reduced amount of cellulosic air felt material. For example, such a core may contain less than about 40%, less than 30%, less than 20%, less than 10%, less than 5%, or even less than about 1% of cellulosic air felt material. Such cores may primarily contain absorbent gel material in amounts of at least about 60%, 70%, 80%, 85%, 90%, 95%, or even about 100%, with the remainder of the core containing microfiber adhesive (where applicable). Such cores, microfiber adhesives, and absorbent gel materials are described in U.S. Patents No. 5,599,335, 5,562,646, 5,669,894, and 6,790,798, and U.S. Patent Publications 2004 / 0158212(A1) and 2004 / 0097895(A1).

[0040] As described above, the diaper 100 may also include an elastic leg cuff 156. The leg cuff 156 may be a leg band, side flap, barrier cuff, elastic cuff, or gasketing cuff, and may be referred to as such in some cases. The elastic leg cuff 156 may be constructed in various ways that help reduce leakage of body exudate in the leg area. Examples of leg cuffs 156 may be described in U.S. Patent Nos. 3,860,003, 4,909,803, 4,695,278, 4,795,454, 4,704,115, 4,909,803, and U.S. Patent Application Publication No. 2009 / 0312730(A1).

[0041] The diaper pants may be manufactured with an annular elastic belt 104 and provided to consumers in a packaged configuration with the front waist region 116 and the rear waist region 118 connected to each other before being applied to the wearer. Thus, the diaper pants may have a continuous outer waist opening 110 and a continuous outer leg opening 112 as shown in Figures 1A and 1B. The annular elastic belt may be formed by joining a first elastic belt to a second elastic belt using a permanent side seam or using an openable and re-closeable fastening system located on or adjacent to the laterally opposing sides of the belt.

[0042] The annular elastic belt 104 may be defined by the first elastic belt 106 connected to the second elastic belt 108. As shown in Figure 2, the first elastic belt 106 extends between the first longitudinal side edge 111a and the second longitudinal side edge 111b, defining the first and second opposing end regions 106a, 106b and the central region 106c. The second elastic belt 108 extends between the first longitudinal side edge 113a and the second longitudinal side edge 113b, defining the first and second opposing end regions 108a, 108b and the central region 108c. The distance between the first longitudinal side edge 111a and the second longitudinal side edge 111b defines the pitch length PL of the first elastic belt 106, and the distance between the first longitudinal side edge 113a and the second longitudinal side edge 113b defines the pitch length PL of the second elastic belt 108. The central region 106c of the first elastic belt may be connected to the first waist region 116 of the chassis 102, and the central region 108c of the second elastic belt 108 may be connected to the second waist region 118 of the chassis 102. As shown in Figures 1A and 1B, the first end region 106a of the first elastic belt 106 may be connected to the first end region 108a of the second elastic belt 108 at the first side seam 178, and the second end region 106b of the first elastic belt 106 may be connected to the second end region 108b of the second elastic belt 108 at the second side seam 180, thereby defining the annular elastic belt 104 and the waist opening 110 and leg opening 112.

[0043] As shown in Figures 2, 3A, and 3B, the first elastic belt 106 also defines an outer laterally extending edge 107a and an inner laterally extending edge 107b, and the second elastic belt 108 defines an outer laterally extending edge 109a and an inner laterally extending edge 109b. In this way, the outer edge 112a of one leg opening can be defined by the laterally extending inner edge 107b of the first elastic belt 106, the laterally extending inner edge 109b of the second elastic belt 108, and the portion of the first longitudinal or right-side edge 128 of the chassis 102. Furthermore, the outer edge 112b of the other leg opening may be defined by a laterally extending inner edge 107b, a laterally extending inner edge 109b, and a portion of the second longitudinal or left side edge 130 of the chassis 102. The laterally extending outer edges 107a and 109a may also define the front waist edge 121 and the laterally extending rear waist edge 122 of the diaper pants 100. The first and second elastic belts may also each include an outer layer 162 facing the outer garment and an inner layer 164 facing the inner wearer. It will be understood that the first elastic belt 106 and the second elastic belt 108 may contain the same material and / or have the same structure. In some embodiments, the first elastic belt 106 and the second elastic belt may contain different materials and / or have different structures. It will also be understood that the first elastic belt 106 and the second elastic belt 108 may be made from a variety of materials. For example, the first and second belts may be made from a wide range of materials such as plastic films, perforated plastic films, natural materials (e.g., wood fibers or cotton fibers), synthetic fibers (e.g., polyolefins, polyamides, polyesters, polyethylene or polypropylene fibers), or woven or nonwoven webs of natural and / or synthetic fibers, or coated woven or nonwoven webs. In some embodiments, the first and second elastic belts may include a web of synthetic fiber nonwoven fabric and may include an elastic nonwoven fabric. In other embodiments, the first and second elastic belts may include an inner hydrophobic, non-stretchable nonwoven fabric material and an outer hydrophobic, non-stretchable nonwoven fabric material.

[0044] Furthermore, the first and second elastic belts 106 and 108 may each further include a belt elastic material interposed between the outer base layer 162 and the inner base layer 164. The belt elastic material may include one or more elastic elements, such as strands, ribbons, films, or panels, that extend along the length of the elastic belt. As shown in Figures 2, 3A, and 3B, the belt elastic material may include a plurality of elastic strands 168, which may be referred to herein as outer waist elastic members 170 and inner waist elastic members 172. The elastic strands 168 (e.g., outer waist elastic members 170) may extend continuously laterally between opposing first end regions 106a and second end regions 106b of the first elastic belt 106, and between opposing first end regions 108a and second end regions 108b of the second elastic belt 108. In some embodiments, the elastic strands 168 (e.g., the inner waist elastic member 172) may be configured to have discontinuities in areas where, for example, the first and second elastic belts 106, 108 overlap the absorbent assembly 140. In some embodiments, the elastic strands 168 may be arranged longitudinally at regular intervals. In other embodiments, the elastic strands 168 may be arranged longitudinally at different intervals. The stretched belt elastic material may be spaced and joined between the non-shrinkable outer layer and the non-shrinkable inner layer. When the belt elastic material is relaxed, it returns to a non-stretched state, causing the outer and inner layers to contract. The belt elastic material may produce a desired change in contraction force within the region of the annular elastic belt. It should be understood that the chassis 102 and the elastic belts 106, 108 may be configured in ways different from those shown in Figure 2. The belt elastic material may be bonded to the outer layer and / or inner layer continuously or intermittently along the interface between the belt elastic material and the outer layer and / or inner layer.

[0045] In some configurations, the first elastic belt 106 and / or the second elastic belt 108 may define a curved profile. For example, the inner lateral edges 107b, 109b of the first and / or second elastic belts 106, 108 may include nonlinear or curved portions in the opposing end regions of the first and second. Such a curved profile may help define a desired shape for a leg opening 112, such as a relatively rounded leg opening. In addition to having a curved profile, the elastic belts 106, 108 may also include elastic strands 168, 172 extending along a nonlinear or curved path that may coincide with the curved profile of the inner lateral edges 107b, 109b.

[0046] The apparatus and methods described herein may be used to manufacture elastomer laminates that can be used to construct various components of diapers, such as elastic belts and leg cuffs. For example, Figures 4 to 8 show various schematic diagrams of a processing apparatus 300 adapted to manufacture an elastomer laminate 302. As described in more detail below, the processing apparatus 300 shown in Figures 4 to 8 operates to advance a continuous length of elastic material 304, a continuous length of a first substrate 306, and a continuous length of a second substrate 308 along the machine direction MD. It should also be understood that in some configurations, the first substrate 306 and the second substrate 308 herein may be defined by two separate substrates or by folded portions of a single substrate. The apparatus 300 can manufacture an elastomer laminate 302 by stretching the elastic material 304 and joining the stretched elastic material 304 to the first and second substrates 306 and 308. The elastic material 304 may be supplied from a rotating beam on which the elastic strand is wound, or from another type of winding supply for the elastic strand. During operation, the elastic material may advance from the rotating beam toward the machine.

[0047] The elastomer laminate 302 can be used to construct various types of diaper components, such as belts, ear panels, side panels, lateral barriers, top sheets, back sheets, cuffs, waistbands, waist caps, and / or chassis. For example, the elastomer laminate 302 can be used as a continuous length elastomer belt material that can be processed into the first and second elastic belts 106, 108 described above in relation to Figures 1 to 3B. Thus, the elastic material 304 can then correspond to a belt elastic material 168 interposed between an outer layer 162 and an inner layer 164, which can then correspond to either the first and / or second base materials 306, 308. In another example, the elastomer laminate can be used to construct a waistband and / or side panels of a tape-type diaper structure. In yet another embodiment, the elastomer laminate can be used to construct various types of leg cuffs and / or top sheet structures. When the elastomer laminate 302 forms at least one part of the group consisting of belts, chassis, side panels, top sheets, back sheets, and ear panels, and combinations thereof, the multiple elastic bodies 318 of the elastomer laminate 302 may contain about 40 to about 1000 elastic strands. Also, when the elastomer laminate 302 forms at least one part of the group consisting of waistbands, waist caps, inner leg cuffs, outer leg cuffs, and combinations thereof, the first multiple elastic bodies 316 of the elastomer laminate 302 may contain about 10 to about 400 elastic strands. Ultimately, “multiple elastic bodies” is a contextual term, and specific properties, arrangements, attributes, features, and configurations of these elastic bodies are referenced to define what a particular “multiple elastic bodies” is.

[0048] As shown in Figures 4 and 5, the processing apparatus 300 for manufacturing the elastomer laminate 302 may include a first metering device 310 and a second metering device 312. The first metering device may be configured as a beam 316 around which a plurality of elastic strands 318 are wound. Figure 6 shows an example of an empty beam 316 including two side plates 317a, 317b which can be connected to both ends of a mandrel core 319, around which the elastic strands can be wound. Depending on the method and apparatus described herein, beams of various sizes and technical specifications may be available, such as beams available from ALUCOLOR Textilmaschinen, GmbH. During operation, the plurality of elastic strands 318 advance in the mechanical direction MD from the beam 316 to the second metering device 312. Furthermore, the plurality of elastic strands 318 may be stretched along the mechanical direction MD between the beam 316 and the second metering device 312. The stretched elastic strands 318 can also be bonded to the first substrate 306 and the second substrate 308 in a second metering device 312 to produce an elastomer laminate 302. However, it should be noted that in some configurations, the elastic strands 318 are not arranged in a beam form. Instead, for example, the first metering device 310 may be a spool of individual elastic strands 318, or a spool of elastic strands 318 that are not otherwise formed in a beam. Thus, the systems and methods described herein are applicable across a range of manufacturing processes that generally require bonding one or more elastic strands to one or more substrates.

[0049] As shown in Figure 4, the second metering device 312 includes a first roller 324 having an outer surface 326 and rotating around a first rotation axis 328, and a second roller 330 having an outer surface 332 and rotating around a second rotation axis 334. The first roller 324 and the second roller 330 rotate in opposite directions, and the first roller 324 may be adjacent to the second roller 330, defining a nip 336 between the first roller 324 and the second roller 330. The first roller 324 may rotate such that its outer surface 326 has a surface velocity V1, and the second roller 330 may rotate such that its outer surface 332 has the same or substantially the same surface velocity V1.

[0050] As shown in Figures 4 and 5, the first substrate 306 includes a first surface 338 and an opposing second surface 340, and the first substrate 306 advances toward the first roller 324. Specifically, the first substrate 306 advances toward the first roller 324 at a speed V1, and the first substrate 306 partially wraps around the outer circumferential surface 326 of the first roller 324 and advances through the nip 336. Thus, the first surface 338 of the first substrate 306 contacts the outer circumferential surface 326 of the first roller 324 and advances in the same direction as the outer circumferential surface 326 of the first roller 324. In addition, the second substrate 308 includes a first surface 342 and an opposing second surface 344, and the second substrate 308 advances toward the second roller 330. Specifically, the second substrate 308 advances toward the second roller 330 at a speed V1, partially wrapping around the outer circumferential surface 332 of the second roller 330, and advancing through the nip 336. Thus, the second surface 344 of the second substrate 308 comes into contact with the outer circumferential surface 332 of the second roller 330 and moves in the same direction as the outer circumferential surface 332 of the second roller 330.

[0051] Continuing to refer to Figures 4 and 5, the beam 316 has elastic strands 318 wound around it, and the beam 316 is rotatable about a first beam rotation axis 346. In some configurations, the first beam rotation axis 346 may extend in the transverse direction CD. As the beam 316 rotates, the elastic strands 318 advance from the beam 316 at a velocity V2, and the elastic strands 318 are spaced about 0.25 mm to 4 mm, or about 0.25 mm to 3 mm, or about 0.25 mm to 2 mm apart from each other in the transverse direction CD. From the beam 316, the elastic strands 318 advance towards the nip 336 in the mechanical direction MD. In some configurations, the velocity V2 is less than the velocity V1, and therefore the elastic strands 318 may be stretched in the mechanical direction MD. Next, the stretched elastic strands 318 advance through a nip 336 between the first substrate 306 and the second substrate 308 so that the elastic strands 318 can be joined to the second surface 340 of the first substrate 306 and the first surface 342 of the second substrate 308 to produce a continuous length elastomer laminate 302. As shown in Figure 4, the first substrate 306 may advance through an adhesive applicator device 348 that applies adhesive 350 to the second surface 340 of the first substrate 306 before advancing to the nip 336. It should be understood that the adhesive 350 can be applied to the first substrate 306 upstream of the first roller 324 and / or while the first substrate 306 is partially wrapped around the outer surface 326 of the first roller 324. It should be understood that the adhesive may be applied to the multiple elastic strands 318 before and / or during bonding with the first substrate 306 and the second substrate 308. Furthermore, it should be understood that the adhesive may be applied to the first surface 342 of the second substrate 308 before and during bonding with the multiple elastic strands 318 and the first substrate 306.

[0052] It should be understood that different components can be used to construct the elastomer laminate 302 by the method and apparatus described herein. For example, the first substrate 306 and / or the second substrate 308 may include nonwovens and / or films. Furthermore, the multiple elastic strands 318 can be configured in various ways and with various decitex values. In some configurations, the multiple elastic strands 318 may be configured to have decitex values ​​in the range of about 10 decitex to about 500 decitex, or about 10 decitex to about 400 decitex, or about 10 decitex to about 300 decitex, specifically listing all values ​​in 1 decitex increments within the above range, and all ranges within or formed by the above range. It should also be understood that the beam 316 can be constructed in various ways and with various amounts of elastic strands. Exemplary beams, also referred to as warp-aligned beams, that can be used in the apparatus and methods of this specification are disclosed in U.S. Patent Nos. 4,525,905, 5,060,881, and 5,775,380, and U.S. Patent Application Publication 2004 / 0219854(A1). Figure 5 shows nine elastic strands 318 advancing from beam 316, but it should be understood that the apparatus of this specification may be configured to have more or fewer elastic strands 318 advancing from beam 316. In some configurations, the multiple elastic strands 318 advancing from beam 316 may include about 100 to about 2000 strands, specifically listing all values ​​in the above ranges of one-strand increments, and all ranges within or formed by the above ranges. In some configurations, the elastic strands 318 may be separated from each other by approximately 0.5 mm to 4 mm in the transverse direction, specifically enumerating all values ​​in 0.1 mm increments within the above range, and all ranges within or formed by the above range. The elastic bodies within the multiple elastic strands may be pre-tensioned before joining the elastic strands to the first or second base material layers 306, 308.In some configurations, the elastic body may be pre-tensioned to approximately 75% to approximately 300%, specifically enumerating all values ​​in 1% increments within the above range, and all ranges within or formed by the above range. It will also be understood that one or more elastic beams can be positioned along the transverse direction CD of the machining process and / or along the machine direction MD in various different parts of the machining process. It will also be understood that the beam 316 can be connected to one or more motors, such as servo motors, to drive and control the rotation of the beam 316.

[0053] It should also be understood that multiple elastic strands 318 may have various different material structures and / or decitex values ​​to produce an elastomer laminate 302 having different stretch properties in different regions. In some configurations, the elastomer laminate may have regions in which the elastic strands are spaced relatively close to each other in the transverse direction CD, and other regions in which the elastic strands are spaced relatively far apart from each other in the transverse direction CD, in order to produce different stretch properties in different regions. In some configurations, the elastic strands may be supplied onto the beam in a stretched state and therefore may not require (or may require relatively little additional stretching) before being combined with the first substrate 306 and / or the second substrate 308.

[0054] Referring here to Figure 7, the adhesion of the elastic strand 318 to the first substrate 306 is schematically shown. As described above, elastic strands wound in a beam configuration under high compression tend to stick together (i.e., crosslink) during unwinding. Therefore, according to this disclosure, a control layer 352 can be applied to the elastic strand 318 of the beam 316 to reduce crosslinking and assist the unwinding process. Furthermore, since the elastic strand 318 can be adhered to the first and second substrate layers 306, 308 via the adhesive 350 (note that only the first substrate 306 is shown in Figure 7 for illustrative purposes), the various properties of the control layer 352 and the adhesive 350 can be specifically selected to enable sufficient adhesion of the elastic strand 318 and the first and second substrate layers 306, 308. More specifically, the control layer 352 applied to the beam 316 can have a solubility level that ensures that the majority of the control layer 352 remains on the surface of the multiple elastic strands 318, as opposed to being absorbed into the strands. This property of the control layer 352 is schematically shown by enlarged view 318A in Figure 7. Thus, when the multiple elastic strands 318 are drawn from the beam 316, undesirable blocking can be reduced or eliminated, even after the beam 316 has been stored under high compression for a period of time before the unwinding of the elastic strands 318.

[0055] However, importantly, the multiple elastic strands 318 also need to be sufficiently bonded to the first and second substrate layers 306, 308 in order to form an elastomer laminate 302 having the desired strength parameters. Therefore, the adhesive 350 can be specially selected to absorb the control layer 352 so that the control layer 352 does not adversely affect the adhesion of the adhesive 350 to the multiple elastic strands 318. Thus, according to this disclosure, the multiple elastic strands 318, the control layer 352 applied to the multiple elastic strands 318, and the adhesive 350 are each specially selected such that the control layer 352 is less likely to be absorbed by the multiple elastic strands 318 and is instead more likely to be absorbed by the adhesive 350. As a result, the elastic strands 318 can be drawn from the beam 316 without blocking, and the adhesive 350 can sufficiently bond the elastic strands 318 and the first and second substrates 306, 308.

[0056] The desired distribution level within the elastomer laminate 302 can be achieved by selecting a control layer 352 having specific solubility parameters and average molecular weight. In particular, the control layer 352 has a solubility of approximately 15.5 MPa. 1 / 2 ~Approx. 16.5MPa 1 / 2 , or approximately 15.8 MPa 1 / 2 ~Approx. 16.5MPa 1 / 2 The solubility parameter may be within the range of approximately 0.6 kg / mol to 1.5 kg / mol, or approximately 0.8 kg / mol to approximately 1.4 kg / mol, or approximately 1.0 kg / mol to approximately 1.3 kg / mol. The control layer 352 may have a surface tension of approximately 24 mN / m to approximately 30 mN / m. Furthermore, the adhesive 350 may have a surface tension of approximately 16 MPa. 1 / 2 ~Approx. 17.5MPa 1 / 2 , or approximately 16.5 MPa 1 / 2 ~Approx. 17.2MPa 1 / 2 The adhesive polymer may have solubility parameters within the range. Multiple elastic strands 318 are approximately 18 MPa. 1 / 2 ~Approx. 18.5MPa 1 / 2 The strand polymer may have a solubility parameter within the range of . According to one embodiment, the strand polymer has a solubility parameter of about 18.3 MPa.1 / 2 It has the following solubility parameters. Furthermore, the number-average molecular weight of the control layer may be lower than the molecular weight of each of the strand polymers of the multiple elastic strands 318 and the adhesive polymer of the adhesive 350.

[0057] For a pair of materials a and b, the χ value associated with their mixture is calculated as follows:

[0058]

number

[0059] According to this disclosure, the χN value between the control layer 352 and the strand polymer of the elastic strand 318 is greater than 2, where N is the degree of polymerization of the control layer and χ is the Florey-Huggins interaction parameter (for additional information regarding the determination of χN according to this disclosure, see "The Physics of Polymers", Gert R. Strobl, ISBN 978-3-642-06449-4). Furthermore, the χN value between the control layer 352 and the adhesive polymer of the adhesive 350 may be less than about 3 or less than about 2. The adhesive 350 may have a rubbery flat modulus of about 0.01 to about 0.3 MPa, 0.02 to about 0.1 MPa, or about 0.1 MPa at 38°C and 1 Hz (for additional information regarding the determination of the flat modulus according to this disclosure, see Pocious AV, "Adhesion and Adhesives Technology - an introduction, 2 ndSee "Edition," Hanser / Gardner Publications, Inc., Cincinnati, OH (2002). ISBN 1-56990-319-0, pages 124-131. Furthermore, the tensile modulus of multiple elastic strands 318 at room temperature may be in the range of approximately 5 MPa to approximately 15 MPa (for additional information regarding the determination of tensile modulus according to this disclosure, see Pocious AV, "Adhesion and Adhesives Technology - an introduction, 2 nd "Edition." Hanser / Gardner Publications, Inc., Cincinnati, OH (2002). ISBN 1-56990-319-0, see pages 17-18. After the formation of the elastomer laminate 302, the control layer 352 may be dispersed from its original position on the surface of the elastic strand 318 when absorbed into the adhesive 350.

[0060] As described above, the beamed elastomers according to this disclosure may be formed from spandex fibers. One type of spandex fiber is a “polyurethane urea” elastomer or a “high hard segment-level polyurethane” elastomer, which can be formed into fibers using a solution (solvent) spinning process (as opposed to those processed in a molten state). The rigid blocks in polyurethane urea provide strong chemical interactions that are important for providing “adhesion,” which enables good stress relaxation performance at near body temperature over time scales corresponding to diaper wear, including overnight. This type of adhesion allows for better stress relaxation over time (i.e., little stress decay over time when held in an extended state at body temperature). In contrast, extruded strands and scrims are typically made from styrene block copolymers or thermoplastic elastomers that can be formed by conventional extrusion processes in a molten state. Thermoplastic elastomers include compositions such as polyolefins and polyurethane (polyurethane with hard segment melting below 200°C) elastomers. These thermoplastic elastomers, such as polyurethane (polyurethane with hard segment melting below 200°C), are susceptible to greater stress relaxation during use because they can melt / remelt and be extruded, which is a major drawback. Styrene block copolymers used in extruded strands have relatively long, rubbery intermediate blocks located between relatively short end blocks. End blocks that are short enough to allow for a good flow in conventional extrusion processes are often highly susceptible to stress relaxation and tend to undergo stress relaxation over time. The urea bonds present in spandex must be created by the spinning process. Spandex cannot melt / remelt like styrene block copolymers. A spandex prepolymer is combined with a solvent and additives, and the solution is spun to create solid spandex fibers. Multiple fibers can then be joined together to form a single spandex strand. The decitex of a single spandex fiber can be about 15, and therefore a 500 decitex strand can have nominally 33 fibers wound together to form one strand.Depending on the decitex used in the beam technique, there may be 40 fibers (or filaments), 30 fibers, 20 fibers, 15 fibers, 8 fibers, 5 fibers, 3 fibers, or even up to 2 fibers. The spandex fibers can be single-component or bi-component (disclosed in WO201045637(A2)).

[0061] Commercially available spandex strands are also known as Lycra, Creora, Roica, or Dorlastan. Spandex is often referred to as elastane fiber or polyurethane fiber. LYCRA HYFIT strands, products of Invista, Wichita, and Kansas, are suitable for creating strands that make up multiple elastic bodies 318 constituting an elastomer laminate 302. Some strands, such as the aforementioned LYCRA HYFIT, can comprise multiple individual fibers wound together to form a strand. With respect to elastic strands formed from multiple individual fibers, it has been found that the individual fibers can move relative to each other, thereby changing the cross-sectional shape of the strand and unraveling, which can lead to poor control of the strand and poor bonding / adhesion / joining of the elastic strand to one or both of the first base layer 306 and the second base layer 308 of the elastomer laminate 302. To minimize the drawbacks of strands comprising multiple fibers, it is advantageous to minimize the number of fibers in a given strand. Therefore, it is desirable to have fewer than approximately 40 fibers per strand, fewer than approximately 30 fibers per strand, fewer than approximately 20 fibers per strand, fewer than approximately 10 fibers per strand, fewer than approximately 5 fibers per strand, and one fiber forming the strand. When a single fiber forms a strand that can provide performance equivalent to a strand made of multiple fibers in the conventional technology, it is desirable that the fiber decitex of the fiber is about 22 to about 300 and the fiber diameter is about 50 micrometers to about 185 micrometers.

[0062] As described above, the control layer 352 helps prevent blocking when multiple elastic strands 318 are wound onto a spool or beam, and at the same time reduces the coefficient of friction of the strands. According to some embodiments, the control layer 352 is a mineral oil, which may be, for example, a paraffinic mineral oil. According to various embodiments, the control layer 352 may include, for example, white mineral oil, polyisoprene, and polybutadiene. In other embodiments, the control layer may be a synthetic oil.

[0063] The control layer 352 may include additional materials to enhance its performance, such as soap (i.e., fatty acids or fatty acid salts), wax, detergent, clay, or anti-caking agents (e.g., silica). The use of soap according to this disclosure is thought to reduce the stickiness of the elastic strand, which can improve handling in the winding process. Furthermore, the use of soap can also provide a beneficial trade-off between unwinding and adhesion.

[0064] In some implementations, a metal soap may be added to a control layer 352 that functions to improve the unwinding of multiple elastic strands 318 from a beam 316. As used herein, the metal soap may be a fatty acid salt produced by the reaction of an alkali metal, alkaline earth metal, or transition metal with a saturated, unsaturated linear or branched aliphatic carboxylic acid having 8 to 22 carbon atoms, or 12 to 18 carbon atoms. Examples include saturated fatty acids such as stearic acid (octadecanoic acid), lauric acid (dodecanoic acid), 12-hydroxystearic acid, and mixtures of acids having 8 to 22 carbon atoms; unsaturated fatty acids such as oleic acid (cis-9-octadecenoic acid) and linoleic acid (9,12-octadecadienoic acid); synthetic carboxylic acids such as isostearic acid, 2-ethylhexanoic acid, dimethylhexanoic acid, trimethylhexanoic acid, and mixtures of synthetic aliphatic isocarboxylic acids; and salts of alicyclic naphthenic acids and resin acids. Various metal ions can be used to produce metal soaps, examples of which include sodium, magnesium, calcium, and zinc. According to one embodiment of the present disclosure, magnesium stearate is used because it is insoluble in both the adhesive 350 and the elastic strand 318. The amount of soap used may vary, but in some embodiments, the control layer 352 contains about 1% to 5% by weight of soap, or about 2% to 4% by weight of soap, or about 3% by weight of soap.

[0065] Referring here to Figure 8, the interaction of the control layer 352 with the multiple elastic strands 318 and adhesive 350 over time is schematically shown. As shown in enlarged view 318A, the control layer 352 is schematically shown to coat the outer surface of the elastic strands 318. If the control layer 352 has a high molecular weight, it will not be significantly absorbed by the elastic strands 318 even if the beam 316 is stored under high compression for a long period of time. Therefore, the control layer 352 functions to beneficially prevent crosslinking and blocking when the elastic strands 318 are finally drawn from the beam 316 during the manufacturing process. As previously mentioned with reference to Figure 4, the processing apparatus 300 manufactures an elastomer laminate 302 formed by a first substrate 306, multiple elastic strands 318, and a second substrate 308. As shown in Figure 8, adhesive 350 may be used to bond the multiple elastic strands 318 to the first and second substrates 306, 308. At a first time point, indicated as time T1 in Figure 8, the control layer 352 begins to disperse within the elastomer laminate 302A. In particular, as described above, due to the relative solubility and number-average molecular weight of the various components of the elastomer laminate 302, the control layer 352 of this disclosure can be absorbed primarily into the adhesive 350. Once the control layer 352 is absorbed into the adhesive 350, the adhesive 350 can properly adhere to the elastic strands 318. Finally, at a second time point, indicated as time T2 in Figure 8, the control layer 352 completes its dispersion and can be substantially absorbed into the adhesive 350. Furthermore, at T2, if the control layer 352 contains soap, the soap does not disperse within the adhesive 350. Instead, a large amount of soap remains between the interface of the elastic strands 318 and the adhesive 350. Therefore, if an excess of soap is used, it may impair the adhesion of the first and second substrates 306, 308 to the elastic strands 318. As shown in Figure 8, the adhesive 350 may come into contact with a portion of the elastic strand 318. Alternatively, the adhesive 350 may substantially or completely encase one or more of the elastic strands 318.

[0066] Consistent with the above outline, preferably, forming an elastomer laminate 302 using a control layer 352 together with multiple elastic strands 318 and adhesive 350 does not result in significantly different laminate properties from the same elastomer laminate 302 made without the control layer 352. For example, an elastomer laminate of the present disclosure including a control layer may have a laminate creep of 5 mm or less, 4 mm or less, or 3 mm or less according to a laminate creep test. These laminate creep values ​​are relative to laminates made of elastic materials including a control layer, and are evidence that the control layer of the present disclosure does not affect the performance of the adhesive. Furthermore, an elastomer laminate of the present disclosure formed with elastic strands including a control layer may have a laminate creep of 2 mm or less or 1 mm or less than the same elastomer laminate formed with elastic strands without a control layer. In practice, an elastomer laminate including a control layer may have less laminate creep (i.e., less creep) than the same elastic laminate without a control layer.

[0067] Furthermore, elastomer laminates of the present disclosure including a control layer may have static peel force times exceeding 700 minutes / 10 mm bond length, 600 minutes / 10 mm bond length, 500 minutes / 10 mm bond length, 400 minutes / 10 mm bond length, or 300 minutes / 10 mm bond length, according to a static peel force time test method. These static peel force time values ​​are for laminates made of elastic materials including a control layer, and are evidence that the control layer of the present disclosure does not affect the performance of the adhesive. Furthermore, elastomer laminates of the present disclosure formed from elastic strands including a control layer may have static peel force times within 5 minutes / 10 mm bond length or within 3 minutes / 10 mm bond length of the same elastomer laminate formed from elastic strands without a control layer, and in practice, elastomer laminates including a control layer may have longer (i.e., longer) static peel force times than the same elastic laminate without a control layer.

[0068] Furthermore, the elastomer laminates of this disclosure, including the control layer, may have a stress relaxation over time of approximately 5% to 30%, 5% to 25%, 10% to 25%, or 15% to 20%, depending on the method of stress relaxation over time. These stress relaxation values ​​are relative to laminates made of elastic materials including the control layer, and are evidence that the control layer of this disclosure does not affect the performance of the adhesive. Furthermore, the elastomer laminates of this disclosure formed from elastic strands including the control layer may have a stress relaxation over time of no more than 15% or 10% of that of the same elastomer laminate formed from elastic strands without the control layer, and in practice, elastomer laminates including the control layer may have less stress relaxation over time (i.e., less stress relaxation) than the same elastic laminate without the control layer. The dimensions and values ​​disclosed herein should not be understood as strictly limited to the exact numerical values ​​listed. Instead, unless otherwise indicated, such dimensions are intended to mean both the listed value and the functionally equivalent range encompassing that value. For example, a dimension disclosed as "40mm" is intended to mean "approximately 40mm".

[0069] All documents referenced herein, including any patents or patent applications that are cross-referenced or related, and any patent applications or patents on which this application claims priority or benefit thereof, are incorporated herein by reference in their entirety unless otherwise explicitly stated to be excluded or limited. No document reference shall be deemed prior art to any invention disclosed or claimed herein, nor shall it be deemed to teach, suggest or disclose any such invention, either alone or in combination with any other reference(s). Furthermore, if any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in any document incorporated by reference, the meaning or definition given to the term in this document shall prevail.

[0070] While specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications within the scope of the invention be covered in the appended claims.

[0071] Test Procedure Unless otherwise specified, tests are conducted under standard laboratory conditions of 22°C and 50% relative humidity.

[0072] Relaxation of forces over time The stress relaxation of the test specimen over time is measured using a constant-speed elongation tensile testing machine with a load cell in which the measured force is within 1% to 90% of the cell's limit (a preferred instrument is the MTS Insight with Testworks 4.0 Software, available from MTS Systems Corp. (Eden Prairie, MN)). Prior to analysis, the articles are conditioned at 23°C ± 2°C and 50% ± 2% relative humidity for 2 hours, and then tested under the same environmental conditions. The sample size is prepared to allow a gauge length of 25.4 mm (parallel to elastic expansion and contraction) in a width of 12.7 mm.

[0073] Program the tensile testing machine to perform elongation and determine the engineering strain when the tensile force reaches 0.0294 N / mm.

[0074] For testing the stress relaxation over time, a second sample is prepared and adjusted as described above. The test is carried out on the same apparatus as described above. The test is carried out at a temperature of 37.8°C. The sample is stretched to the strain determined above. The sample is held for 10 hours, and the force is recorded at a rate of at least 5 Hz during strain application, at least 5 Hz during the first minute of stress relaxation, and thereafter at a rate of at least 0.05 Hz (one point every 20 seconds) throughout the experiment.

[0075] Laminate creep test method ("Laminate creep") The laminate creep test method is used to characterize the movement of the ends of stretched elastic strands 318 of a stretched elastomer laminate away from the cut edge 472 of the same laminate.

[0076] Device The stretch board 400 is prepared from an acrylic or polycarbonate sheet, an example of which is shown in Figure 9. The width of the stretch board 400 is 250 to 375 mm, and the length of the stretch board 400 is at least the width of the laminate being tested. Hook material 402, which can secure the elastomer laminate, is attached to the front side of the stretch board 400 and extends in the longitudinal direction. Two courses of hooks 402, each approximately 50.8 mm wide and extending the length of the stretch board 400, are positioned symmetrically around the center line 404 of the stretch board 400, resulting in a 12 mm gap (indicated as gap "G") between the courses of hooks, which exposes a gap of bare acrylic or polycarbonate sheet extending the entire length of the stretch board 400 where no hooks are attached. Two course hooks 406, each at least 13 mm wide and extending along the length of the board, are attached to the underside of the widthwise edge of the board to facilitate the holding of the stretched laminate across the entire width of the front side of the board.

[0077] Sample preparation Five similar test specimens representing the sample elastomer laminate are cut. The elastomer laminate test specimens are cut portions that, in their stretched state, are at least the same width as the stretch board 400 prepared above, and that can be wrapped around the widthwise edge of the stretch board 400 and secured by the hook material 406 on the back. Each elastomer laminate test specimen may be taken from a roll stock, or, if a roll stock is unavailable, may be cut from a finished disposable absorbent article.

[0078] Each elastomer laminate test specimen is positioned on the stretch board 400, fully stretched so that the elastic strands 318 extend in the width direction of the stretch board 400, perpendicular to the course of the hooks 402 that extend along the length of the stretch board, as shown by specimen 450 in Figure 10. Specimen 450 is held in a stretched state, positioned by the two courses of hook material 402 that extend along the length of the stretch board 400. Although specimen 450 remains in a stretched state, the ends of the specimen are wrapped around the widthwise edge of the stretch board 400 and secured to the hook material 406 on the back, holding the entire laminate of specimen 450 in a stretched state.

[0079] Using a black permanent marker, a 5 mm line 462 (Figures 10 and 11) is marked in the width direction of the specimen laminate. The black marker is applied thickly enough so that the elastic strands 318 of the underlying elements of the elastomer laminate are blackened. The line extends in the length direction of the stretch board, is located in the center of the stretch board 400, and lies in the center of the 12 mm gap between the two courses of hook material 402 which also extend in the length direction. The laminate is then cut along the center line 404 at the center of this 5 mm wide line 462 using a utility knife or razor blade. The stretch board 400 to which the cut specimen laminate is attached is then placed in an oven at 38°C for 120 minutes.

[0080] Measurement and analysis The stretch board 400 is placed in the oven for 120 minutes, then removed and immediately analyzed as shown in Figure 11. The ends of the elastic strands 318 that have undergone significant creep from the initial stretched position are clearly visible as black dots 452 that have moved away from the centerline 404. The widthwise distance (distance "C") from the cut edge 472 to each of the displaced black dots is recorded in millimeters. In total, five similar elastomer laminate specimen replicas are analyzed in this manner. The arithmetic mean of the recorded displacement distances between the five replica specimens is calculated and reported in millimeters as "laminated creep".

[0081] Static peeling force time test method ("Static peeling force time") The static peel force time test method is used to determine the time required for an elastomer laminate to completely delaminate with a peel shape of approximately 180° under a constant load and fixed temperature. Delamination is performed so that the delamination crack propagates parallel to the elastic strands of the elastomer laminate. Multiple test specimens of a representative sample elastomer laminate are obtained from roll stock (if available) or one or more disposable absorbent articles and analyzed to establish the static peel force time.

[0082] Sample preparation If the elastomer laminate is available in roll stock, 10 test specimens with a mechanical length of 27 mm and a transverse length of 25.4 mm are randomly taken from the equilibrated roll stock. If the exemplary laminate is not available in roll stock, the laminate test specimens are cut from one or more finished disposable absorbent articles. In this case, the test specimens must have a length of 27 mm parallel to the direction of the elastic strands and a length of 25.4 mm perpendicular to the direction of the elastic strands.

[0083] For each specimen, the nonwoven fabric layer of the laminate is manually peeled away by 10–15 mm in a direction parallel to the elastic strands. (Free spray may be used very locally to enable the separation of the nonwoven fabric.) For each replica, the dimensions of the remaining bonded area parallel to the direction of the elastic strands are measured and recorded in 1 mm increments.

[0084] Regardless of where the specimens for peel analysis are supplied, each unbonded layer at the edge of the laminate is folded separately onto a small, round wooden dowel rod, 2 mm in diameter and approximately 40 mm long. The wrapped dowels are then secured with 2-inch wide double clips. The clips are positioned on the wrapped dowels and secured to the folded layers of the material to prevent the material from slipping or coming loose from the clips.

[0085] measurement With the clips attached, the test specimens are placed in a pre-conditioned incubation chamber (38±1℃) for approximately 2 hours before testing. After 2 hours, each sample is suspended in the chamber by a clip attached to one of the laminate layers, and a weight is attached to the clip on the other laminate layer and suspended from it. The total mass of the suspended weight, double clip, and dowel is 200±2g.

[0086] Each specimen is suspended so that the bottom of the attached weight is positioned at a sufficient height above the bottom of the chamber, allowing the entire laminate to delaminate and the weight to fall freely to the bottom of the chamber over some remaining distance. A timer is used to measure the time between the time the suspension weight is attached and the time it takes for the bond area of ​​the test laminate to completely delaminate. For each specimen, the time to this failure is recorded in minutes.

[0087] Analysis and Reporting For each test specimen, the time until failure is normalized to a joint dimension of 10 mm to establish the normalized suspension time for the test specimen, and this is recorded in minutes for each test specimen.

[0088]

number

[0089] The arithmetic mean of the normalized suspension time values ​​for 10 test specimens is calculated and reported in minutes as static peel force time.

[0090] Average decitex ("average Dtex") The average Dtex is calculated on a length-weighted basis for the elastic fibers present in a complete article or in a test specimen extracted from an article, using the average dex method. The dex value is the mass in grams of the fibers present in 10,000 meters of that material in a relaxed state. The dex value of elastic fibers or elastomer laminates containing elastic fibers is often reported by the manufacturer as part of the specifications for the elastic fibers or elastomer laminates containing elastic fibers. The average Dtex can be calculated from these specifications if available. Alternatively, if these specified values ​​are unknown, the dex value of individual elastic fibers is measured by determining the cross-sectional area of ​​the relaxed fiber via a suitable microscopy technique such as scanning electron microscopy (SEM), determining the fiber composition via Fourier transform infrared (FT-IR) spectroscopy, and then calculating the mass in grams of the fibers present in 10,000 meters of fiber using literature values ​​for the density of the composition. The decitex values ​​for individual elastic fibers removed from a complete article or a sample extracted from an article, provided by the manufacturer or measured experimentally, are used in the formula described below, in which the length-weighted average of the decitex values ​​among the present elastic fibers is determined.

[0091] The length of each elastic fiber present in an article or a sample extracted from an article is calculated, if known, from the overall dimensions of the component of the article or the sample, and the elastic fiber pre-strain ratio associated with the component of the article or the sample. Alternatively, if the dimensions and / or elastic fiber pre-strain ratio are unknown, the absorbent article or a sample extracted from an absorbent article is disassembled and all elastic fibers are removed. This disassembly can be performed, for example, by gently heating to soften the adhesive and using a low-temperature spray (e.g., Quick-Freeze® from Miller-Stephenson Company, Danbury, Connecticut), or by using a suitable solvent that removes the adhesive without expanding, altering, or destroying the elastic fibers. The length of each elastic fiber in its relaxed state is measured and recorded to the nearest millimeter (mm).

[0092] Calculation of average Dtex The relaxation length L present in the absorbent article or a test specimen extracted from the absorbent article. i and fiber decitex value d i Each elastic fiber f (either obtained from the manufacturer's specifications or measured experimentally) is a separate elastic fiber f i For each of these, the average Dtex of the absorbent article or the test specimen extracted from the absorbent article is defined as follows:

[0093]

number

[0094] If the decitex value of any individual fiber is not known from the specifications, it should be determined experimentally as described below, and the resulting fiber decitex values ​​should be used in the above formula to determine the average Dtex.

[0095] Determination of fiber decitex values ​​by experiment For each elastic fiber extracted from an absorbent article or a sample extracted from an absorbent article according to the above procedure, each elastic fiber L k The length of the relaxed state is measured and recorded to the nearest millimeter (mm). Each elastic fiber is analyzed via FT-IR spectroscopy to determine its composition and density ρ k This is determined from available literature values. Finally, each fiber is analyzed via SEM. The fiber is cut perpendicularly along its length at three approximately equal positions using a sharp blade to create clean cross-sections for SEM analysis. These three fiber sections with exposed cross-sections are mounted in a relaxed state on an SEM sample holder, sputter-coated with gold, introduced into the SEM for analysis, and imaged with sufficient resolution to clearly reveal the fiber cross-sections. To minimize any oblique strain in the measured cross-sections, the fiber cross-sections are oriented as perpendicular as possible to the detector. The shape of the fiber cross-sections can vary, and some fibers may consist of multiple individual filaments. In any case, the area of ​​each of the three fiber cross-sections is determined (e.g., the diameter of a circular fiber, the major and minor axes of an elliptical fiber, and using image analysis of more complex shapes), and the three areas a of the elastic fiber are determined. k The average is square micrometers (μm). 2 ) as the unit, 0.1 μm 2 It is recorded in units of decitex d of the k-th elastic fiber measured. k It is calculated as follows:

[0096]

number

[0097] Average strand spacing Using a ruler calibrated against a certified NIST ruler and accurate to within 0.5 mm, measure the distance between two distal strands within a section to within 0.5 mm, and then divide by the number of strands in that section minus 1. Average strand spacing = d / (n-1) (where n>1) Report in units of 0.1 mm.

Claims

1. A disposable absorbent article in the form of a diaper or absorbent pants, comprising a liquid-permeable top sheet (138), a liquid-impermeable back sheet (136), and an absorbent core (140) disposed between the liquid-permeable top sheet (138) and the liquid-impermeable back sheet (136), The elastomer laminate (302) comprises a plurality of elastic strands (318) spaced apart from each other and bonded to a nonwoven web material (306) by an adhesive (350), The elastic strand (318) comprises a strand polymer, and the strand polymer has a density of 18 MPa. １／２ ~18.5 MPa １／２ Having solubility parameters within the range, The adhesive (350) comprises an adhesive polymer, and the adhesive polymer has a pressure of 16 MPa. １／２ ~17.5 MPa １／２ Having solubility parameters within the range, The elastic strand (318) and / or the adhesive (350) includes a control layer, the control layer having a pressure of 15.5 MPa １／２ ~16.5 MPa １／２ It has a solubility parameter within the range and a number-average molecular weight within the range of 0.6 kg / mol to 1.5 kg / mol. The elastic strand is a disposable absorbent article having an average Dtex of 10 to 500.

2. The disposable absorbent article according to claim 1, wherein the number average molecular weight of the control layer is lower than the molecular weight of the strand polymer and the adhesive polymer, respectively.

3. The disposable absorbent article according to claim 1 or 2, wherein the χN value between the control layer and the strand polymer is greater than 2, and the χN value between the control layer and the adhesive polymer is less than 2, where N is the degree of polymerization of the control layer and χ is the Florey-Huggins interaction parameter.

4. The aforementioned strand polymer is 18.3 MPa １／２ A disposable absorbent article according to any one of claims 1 to 3, having the solubility parameter.

5. The disposable absorbent article according to any one of claims 1 to 4, wherein when the elastomer laminate is subjected to a laminate creep test, the elastomer laminate has a laminate creep of 5 mm or less.

6. The disposable absorbent article according to any one of claims 1 to 5, wherein the elastomer laminate has a static peel force time of more than 700 minutes / 10 mm.

7. The disposable absorbent article according to any one of claims 1 to 6, wherein the adhesive at 38°C has a flat portion elastic modulus of 0.1 MPa at 38°C and 1 Hz.

8. A disposable absorbent article according to any one of claims 1 to 7, wherein the tensile modulus of the elastic strand at room temperature is in the range of 5 MPa to 15 MPa.

9. The disposable absorbent article according to any one of claims 1 to 8, wherein the elastomer laminate including the elastic strands forms at least a portion of a disposable article component selected from the group consisting of a belt, ear portion, side panel, cuff, waistband, back sheet, and top sheet.

10. The disposable absorbent article according to any one of claims 1 to 9, wherein the control layer is mineral oil.

11. The disposable absorbent article according to claim 10, wherein the mineral oil is a paraffinic mineral oil.

12. The disposable absorbent article according to any one of claims 1 to 9, wherein the control layer comprises white mineral oil, polyisoprene, and polybutadiene.

13. The disposable absorbent article according to any one of claims 1 to 9, wherein the control layer is a synthetic oil.

14. The disposable absorbent article according to any one of claims 1 to 13, wherein the control layer contains soap, and the soap is magnesium stearate.

15. The disposable absorbent article according to any one of claims 1 to 14, wherein the strand polymer comprises segmented polyurethane and the adhesive polymer comprises a styrene-based block copolymer.

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