Circular elastic belt with improved side seams

Abstract

A circular elastic belt (104) having a longitudinal direction and a lateral direction is disclosed, the circular elastic belt (104) including a pair of side seams joining the side edges of the front belt (106) and the back belt (108) such that a front fold (162FO) and a back fold (162FO) cooperatively define a distal edge of the circular elastic belt (104), the side seams being made by hot air bonding that at least partially melts the material of the elastic laminate, the side seams having continuity of the melted material along substantially the entire longitudinal dimension thereof, the side seams having a minimum belt peel strength of at least about 6 N / 25 mm, a maximum belt peel strength of no more than 18 N / 25 mm, and a top-to-bottom differential of no more than 15%, as measured herein. Also disclosed is a method for manufacturing an annular elastic belt (104), the method comprising intermittently splicing an assembly of substrates by compressing the molten portions between an outer peripheral surface (370) of an anvil roll (368) and a pressing member (380), the outer peripheral surface of the anvil roll including a grooved region (370G) and a flat region (370F), and the continuous fold region (466FO) is configured to meet the grooved region (370G) of the anvil roll upon compression. Also disclosed is a method for manufacturing an annular elastic belt (104), the method comprising intermittently splicing an assembly of substrates by compressing the molten portions between the outer peripheral surface (370) of an anvil roll (368) and a pressing member (380), the pressing member (380) including a normal surface (423) and a concave surface (421), and a continuous fold (466FO) region configured to meet the concave surface of the pressing member (380).

Description

[Technical Field]

[0001] The present invention relates to a circular elastic belt having improved side seams, articles including the circular elastic belt, and methods of making the same. [Background technology]

[0002] Infants, young children, and other incontinent individuals wear absorbent articles such as pants to receive and contain urine and other body exudates. Pull-on, or pant-type, absorbent articles are donned by inserting the wearer's legs into the leg openings and sliding the article upward into position around the lower torso. Pant-type absorbent articles are popular not only for infants who can walk and are often toilet training, but also for younger, more active children who tend to have more difficulty applying tape-on absorbent articles.

[0003] Belt-type pants having a central chassis covering the wearer's crotch region and separate elastic belts defining the waist and leg openings, as described in International Publication WO 2006 / 17718(A), are known in the art. Such belt-type pants have an elastic belt made from a laminate of nonwoven layers sandwiched between elastic. These elastic belts can be economically produced by overlapping and joining two such laminates to form front and back belts, and then seaming the laminate to form side seams. Recently, various nonwoven materials have been used to meet consumer needs, and some materials may have lower processing resistance. For example, nonwoven materials with good loft and feel may have a lower tensile break point. When a laminate is made from two nonwoven layers, one of the layers may be folded to avoid sharp edges at the waist or leg openings. Thus, the elastic belt may be provided with three layers in the area with the fold and two layers in other areas, resulting in variations in caliper and basis weight along the side seams. Furthermore, the elastic belt may be constructed to have an ergonomic fit, resulting in different positioning of the elastic from the front and back belts. All of the above non-uniformities in the side seams can make the side seaming process difficult to control and / or result in side seams with varying quality of seam strength. Summary of the Invention [Problem to be solved by the invention]

[0004] Based on the above, there is a need to provide a circular elastic belt for a belt-type pant article having side seams that are easy to open after use for removal while withstanding normal use conditions. Further, there is a need for a reliable, high-speed method for making the side seams of a belt-type pant article across a variety of conditions for making the elastic belt and in an economical manner. [Means for solving the problem]

[0005] The present invention is directed to an annular elastic belt (104) having a longitudinal direction and a transverse direction, the annular elastic belt (104) comprising: The front belt (106) and the rear belt (108) each comprise an elastic laminate including a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162) and the second substrate layer (164), and each of the front belt (106) and the rear belt (108) comprises a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the ... second substrate layer (164). a front belt (106) and a rear belt (108) further comprising a folded portion (162FO) of at least one of the first base layer (162) and the second base layer (164), wherein the folded portion (162FO) of the front belt (106) has a shorter longitudinal dimension than the front belt (106), and the folded portion (162FO) of the rear belt (108) has a shorter longitudinal dimension than the front belt (106); a pair of side seams joining the side edges of the front belt (106) and the back belt (108) so that the front folded portion (162FO) and the back folded portion (162FO) cooperatively define a distal edge of the annular elastic belt (104), the side seams being created by hot air bonding which at least partially melts the material of the elastic laminate, the side seams having continuity of the melted material along substantially the entire longitudinal dimension thereof; The side seams have a minimum belt peel strength of at least about 6 N / 25 mm, a maximum belt peel strength of no more than 18 N / 25 mm, and a top to bottom differential of no more than 15% as measured herein.

[0006] The present invention is also directed to a method for manufacturing such an annular elastic belt (104). [Brief explanation of the drawings]

[0007] While the specification concludes with claims that particularly identify and separately claim the subject matter regarded as constituting the invention, it is believed that the invention will be better understood when read in conjunction with the accompanying drawings, in which substantially identical elements are designated with like numerals, and the following description, in which: [Figure 1] FIG. [Figure 2] FIG. 2 is a partially cutaway plan view of the pants shown in FIG. [Figure 3A] 3A is a cross-sectional view of the pants of FIG. 2 taken along line 3A-3A. [Figure 3B] 3B is a cross-sectional view of the pants of FIG. 2 taken along line 3B-3B. [Figure 4] FIG. 1 is a schematic side view of a converting device adapted to produce pants. [Figure 5A] 5 is a view of a plurality of individual chassis spaced apart from one another along the machine direction and connected to continuous front and back belts taken along line AA of FIG. 4. FIG. [Figure 5B] 5 is a view taken along line BB of FIG. 4 of multiple individual chassis and continuous front and rear belts folded over and connected to each. [Figure 5C] 5 is a view of the folded continuous article taken along line CC of FIG. 4. [Figure 5D] 5 is a view of two separate pant articles taken along line DD of FIG. 4. [Figure 6A1] 1 is a schematic side view of a first embodiment of a coupling module. [Figure 6A2] FIG. 10 is a schematic side view of a second embodiment of a coupling module. [Figure 6A3] FIG. 10 is a schematic side view of a third embodiment of a coupling module. [Figure 6A4] FIG. 10 is a schematic side view of a fourth embodiment of a coupling module. [Figure 6A5] FIG. 10 is a schematic side view of a fifth embodiment of a coupling module. [Figure 6B1] FIG. 2 is a schematic side view of a splicing drum. [Figure 6B2] FIG. 10 is a schematic side view of another splicing drum. [Figure 6B3] FIG. 6B3 is a front view of the splicing station of FIG. 6B2, showing the hot air nozzles. [Figure 6C] FIG. 2 is a front view of the anvil roll. [Figure 6D] FIG. [Figure 7] 1 is a model of a force distribution chart for obtaining average peel strength and material break point as measured herein. DETAILED DESCRIPTION OF THE INVENTION

[0008] definition As used herein, the following terms shall have the meanings specified below.

[0009] "Wearable article" refers to a wearable article that may be in the form of pants, tape pants, incontinence briefs, feminine hygiene garments, etc. A "wearable article" may be configured to absorb and contain various bodily exudates, such as urine, feces, menstrual blood, etc. A "wearable article" may serve as an outer cover that is adaptable to be joined with a separable disposable absorbent insert to provide the absorption and containment functions, such as that disclosed in WO 2011 / 087503(A).

[0010] "Pants" refers to wearable articles having preformed waist and leg openings. Pants may be worn by inserting the wearer's legs into the leg openings and sliding the pants into position about the wearer's lower torso. Pants are also commonly referred to as "closed pants," "prefastened pants," "pull-on pants," "training pants," and "pants."

[0011] "Longitudinal" refers to a direction extending substantially perpendicular from a waist edge to an opposing waist edge of the article and generally parallel to the greatest linear dimension of the article. "Transverse" refers to a direction perpendicular to the longitudinal direction.

[0012] "Body-facing" and "garment-facing" refer to the relative position of an element, or a surface of an element, or a group of elements, respectively. "Body-facing" means that the element or surface is closer to the wearer during wear than any other element or surface. "Garment-facing" means that the element or surface is farther away from the wearer during wear than any other element or surface (i.e., the element or surface is closer to the wearer's garment, which may be worn over the disposable absorbent article).

[0013] "Location" refers to an element being placed in a particular place or position.

[0014] "Bonded" refers to an element being directly affixed to other elements by directly attaching the element to the other elements, and also to an element being indirectly affixed to other elements by attaching the element to intermediate members that are in turn affixed to the other elements.

[0015] "Proximal" refers to the portion closer to the longitudinal center of the article, and "distal" refers to the portion further from the longitudinal center of the article.

[0016] "Water-permeable" and "water-impermeable" refer to the permeability of a material in the context of recessed use of a disposable absorbent article. Specifically, the term "water-permeable" refers to a layer or layer structure having holes, openings, and / or interconnected voids that allow liquid water, urine, or synthetic urine to pass through the thickness of the layer or layer structure in the absence of compressive pressure. Conversely, the term "water-impermeable" refers to a layer or layer structure in which liquid water, urine, or synthetic urine cannot pass through the thickness of the layer or layer structure in the absence of compressive pressure (other than natural forces such as gravity). A layer or layer structure that is water-impermeable by this definition may be permeable to water vapor, i.e., may be "vapor-permeable."

[0017] "Extensible" and "stretchable" mean the ability to stretch or increase the width or length of a component in a relaxed state.

[0018] "Elasticated" or "elasticated" means that a component includes at least a portion made from an elastic material.

[0019] The terms "extensible material," "stretchable material," or "elastic material" are used interchangeably and refer to a material that, upon application of a biasing force, can be stretched without rupture or breakage to an elongated length of at least about 110% of its original relaxed length (i.e., it can be stretched 10% longer than its original length) as measured by EDANA Method 20.2-89, and that, upon removal of the applied force, exhibits a slight recovery of less than about 20% of that elongation without complete rupture or breakage. Such an extensible material is considered "elastic" or "elastomeric" if it recovers at least 40% of its elongation upon release of the applied force. For example, an elastic material with an initial length of 100 mm can be stretched to at least 150 mm and retracts to a length of at least 130 mm (i.e., exhibits 40% recovery) upon removal of the force. An extensible material is considered to be "substantially inelastic" or "substantially non-elastomeric" if, upon release of an applied force, the material recovers less than 40% of its elongation. For example, an extensible material having an initial length of 100 mm can be stretched to at least 150 mm and retracts to a length of at least 145 mm upon removal of the force (i.e., exhibiting 10% recovery).

[0020] "Radial" means a direction extending from the center of the drum toward the outer periphery of the drum.

[0021] By "substrate" herein is meant a material that is primarily two-dimensional (i.e., in the XY plane) and has a thickness (Z direction) that is relatively small (i.e., 1 / 10 or less) compared to its length (X direction) and width (Y direction). Non-limiting examples of substrates include webs, layers or films and foils, such as fibrous materials, nonwovens, polymeric films or metal foils. These materials may be used alone or may include two or more layers laminated together. Thus, a web is a substrate.

[0022] "Nonwoven" means a material made from continuous (long) filaments (fibers) and / or discontinuous (short) filaments (fibers) by processes such as spunbonding, meltblowing, carding, etc. Nonwovens do not have a woven or knitted filament pattern.

[0023] "Machine direction" means the direction of flow of material through a process. Additionally, the relative placement and movement of material may be described as flowing in the machine direction through a process from upstream in the process to downstream in the process.

[0024] "Cross-machine direction" means a direction generally perpendicular to the machine direction.

[0025] Detailed Description of the Invention Circular Elastic Belt Figures 1 and 2 show an example of belt-type pants (100) comprising a circular elastic belt (104) of the present invention. Figure 1 shows a perspective view of the belt-type pants (100) in a pre-fastened configuration, and Figure 2 shows a schematic plan view of the belt-type pants (100) with the seams unbonded and exposing the garment-facing surface in a flat, uncontracted state. The belt-type pants (100) shown in Figures 1 and 2 include a chassis (102) and a circular elastic belt 104. As will be described in further detail below, a front belt (106) and a back belt (108) are joined together to form the circular elastic belt (104).

[0026] Continuing with reference to Figure 2, the article includes a front waist region (116), a back waist region (118), and a crotch region (120) disposed intermediate the front and back waist regions. The pants (100) may also include a laterally extending distal edge (121) of the front waist region (116) and a longitudinally opposite, laterally extending distal edge (122) of the back waist region (118). To provide a frame of reference, the pants (100) and chassis (102) in Figure 2 are shown with a longitudinal axis (124) and a lateral axis (126). The longitudinal axis (124) may extend through the front waist edge (121) and the back waist edge (122). The lateral axis (126) may then extend through a first longitudinal or right edge (128) and through the midpoint of a second longitudinal or left edge (130) of the article.

[0027] As shown in Figures 1 and 2, the belt-type pants (100) may include a chassis (102) including a backsheet (136) and a topsheet (138). The chassis (102) may also include an absorbent assembly (140) including an absorbent core (142) disposed between a portion of the topsheet (138) and the backsheet (136). The pants (100) may also include other features, such as leg elastics (168) and / or leg cuffs, to enhance the fit around the legs of the wearer.

[0028] 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 edge (144) disposed in the first waist region (116), and a second laterally extending edge (146) disposed in the back waist region (118). All side edges (128, 130) extend longitudinally between the first edge (144) and the second edge (146). As shown in FIG. 2 , the laterally extending end edges (144, 146) are located longitudinally inward from the laterally extending front waist edge (121) in the front waist region (116) and longitudinally inward from the laterally extending back waist edge (122) in the back waist region (118). When the belt-style pants (100) are worn around a wearer's lower torso, the front distal edge (121) and the back distal edge (122) of the chassis (102) may encircle a portion of the wearer's waist. At the same time, the chassis side edges (128, 130) may encircle at least a portion of the wearer's legs. And the crotch region (120) may extend from the front waist region (116), through the crotch region (120), to the back waist region (118) and be positioned generally between the wearer's legs.

[0029] Belt-style pants (100) including the circular elastic belt (104) of the present invention are provided to consumers in a packaged configuration in which the front waist region (116) and the back waist region (118) are connected to one another prior to application to a wearer. Thus, the belt-style pants (100) may have a continuous perimeter waist opening (110) and continuous perimeter leg openings (112) as shown in FIG. 1. The circular elastic belt (104) is defined by a front belt (106) connected to a back belt (108). As shown in FIG. 2, the front belt (106) defines left and right regions (106a, 106b) and a central region (106c), and the back belt (108) defines left and right regions (108a, 108b) and a central region (108c).

[0030] The central region (106c) of the first elastic belt may be connected to the front waist region (116) of the chassis (102), and the central region (108c) of the rear belt (108) may be connected to the rear waist region (118) of the chassis (102). As shown in Figure 1, the left region (106a) of the front belt (106) is connected to the left region (108a) of the rear belt (108) at a first side seam (178), and the right region (106b) of the front belt (106) is connected to the right region (108b) of the rear belt (108) at a second side seam (180), thereby defining the circular elastic belt (104) and the waist opening (110) and leg openings (112). As shown in Figures 2, 3A, and 3B, the front belt (106) also defines a distal edge (107a) and a proximal edge (107b), and the back belt (108) defines a distal edge (109a) and a proximal edge (109b). The distal edges (107a, 107b) may also define a front waist edge (121) and a laterally extending back waist edge (122). Referring to Figure 1, when assembled into a pant article, the areas where the side seams (178, 180) are formed do not overlap with the chassis (102), but rather the body-facing sides of the front and back belts (106, 108) directly face each other. Referring to FIG. 5C, the area where the front and back belts (106, 108) directly overlap one another is defined as the overlap area (362).

[0031] 2, 3A, and 3B, each of the front belt (106) and the back belt (108) can be provided with elasticity by forming a laminate including a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162) and the second substrate layer (164). The plurality of elastic bodies (168) may be arranged to extend in the lateral direction. The plurality of elastic bodies (168) may be arranged to extend parallel to each other. The plurality of elastic bodies (168) may also be referred to herein as outer elastic bodies (170) and inner elastic bodies (172). The first substrate layer (162) has a larger longitudinal dimension than the second substrate layer (164) and may therefore extend beyond the distal edge of the second substrate layer (164) to form a fold (162FO), which is folded at the distal edge and attached to the laminate. In Figures 3A and 3B, the fold (162FO) is folded to sandwich the second substrate layer (164), but the fold (162FO) may also be folded away from the second substrate layer (164) and attached to the first substrate layer (162). The fold (162FO) may avoid sharp distal edges or may provide bulk to the elastic laminate. The folded portion (162FO) of the front belt (106) has a shorter longitudinal dimension than the front belt (106), and the folded portion (162FO) of the back belt (108) has a shorter longitudinal dimension than the front belt (106). This folding (162FO) provides the laminate in regions having two substrate layers and three substrate layers. The inner elastic (172) may be disposed in the two-layer region, while the outer elastic (170) may be disposed in the three-layer region. The three-layer region may have a maximum basis weight of at least about 90 gsm.

[0032] The first and second substrate layers (162, 164) may be the same or different materials and may be selected to provide properties such as breathability, softness, cushioning, loft, and combinations thereof, depending on the desirability of the resulting article. The first and second substrate layers (162, 164) may have the same or different basis weights, stiffnesses, textures, or any combination thereof. The first and second substrate layers (162, 164) may have a basis weight of about 5 gsm to about 45 gsm and may be made by processes such as meltblowing, spunbonding, spunlacing, carding, or airlaid, and may include fibers and / or filaments made from natural fibers such as polypropylene (PP), polyethylene (PE), polyethylene phthalate (PET), polylactic acid / polylactide (PLA) or conjugate fibers (PE / PET, PE / PP, PE / PLA, etc.), as well as cotton or regenerated cellulose fibers such as viscose or lyocell. The first and second substrate layers (162, 164) may also be multi-layer or composite structures that combine nonwovens made by different processes and fibers, such as combining spunbond and carded nonwovens. The first and second substrate layers (162, 164) may be made of biodegradable materials or derived from renewable resources.

[0033] One or both of the first and second substrate layers (162, 164) may have a plurality of openings or bonds. While the openings and bonds provide various benefits to the wearer, such as loft, softness, and breathability, such treatments may also provide the substrate layer with a relatively low material break point, such as a material break point of less than about 8 N, or less than about 7 N, as measured herein. If the substrate layer has a relatively low material break point, this can cause the substrate layer to separate when the side seams tear to open the article after use. That is, force applied to the side seams may tear the side seams open in the lateral direction of the article, causing the substrate to tear in this direction. The circular elastic belt of the present invention has side seam characteristics selected to avoid such tearing, even when a substrate layer with a relatively low material break point is used.

[0034] One or both of the first and second base layers (162, 164) may have a plurality of openings. The openings have an opening ratio of about 5% to about 50% and a diameter of about 0.1 mm. 2 ~about 25mm 2 The openings may have an effective open area of 0.01 mm or less. The openings may be apertures, slits, etc. The openings may be apertures having an aspect ratio of less than about 5. The openings may be created by a male-female hot pin process, a punching process, a hydroentangling process using water jets and screens to create holes, and combinations thereof. The openings may be created by creating multiple weakened locations using heat or pressure followed by incremental stretching, as described in U.S. Pat. No. 5,628,097, which is incorporated herein by reference in its entirety, causing the nonwoven web to tear at the weakened locations. Such tearing methods may be particularly useful for nonwovens using spunbond and meltblown fibers. The openings may be three-dimensional, non-uniform, and non-aligned, and may form a pattern, as disclosed in WO 2016 / 73712, which is incorporated herein by reference in its entirety.

[0035] One or both of the first and second substrate layers (162, 164) may have multiple bonds. The bonds have a bond area of about 4% to about 18% and a bond density of about 0.3 mm 2 ~about 10mm 2 The bonds may have a bond area of 0.05 mm to 0.1 mm. The bonds may be in a variety of shapes, including but not limited to, circular, oval, straight or curved, and may be separate or connected. The bonds may be referred to as embossing or quilting. The bonds may be made by calendar bonding, optionally assisted by air compression. The bonds may be those disclosed in WO 2012 / 134988, which is incorporated herein by reference in its entirety.

[0036] Non-limiting examples of materials suitable for the first and second substrate layers (162, 164) of the present invention include 12-30 gsm carded air-through nonwoven substrates made from PE / PET bicomponent staple fibers, such as those available from Beijing Dayuan Nonwoven Fabric Co. Ltd. or Xiamen Yanjan New Material Co. Ltd., and 8-30 gsm spunmelt nonwoven substrates comprising PP monofilament or PE / PP bicomponent fibers, such as those available from Fibertex or Fitesa.

[0037] 3A and 3B, the elastics (168) may be disposed between the front and back sides and at different longitudinal positions of the belt with the same or different denier, spacing, or force. The elastics (168) may be disposed intermittently at various spacings, and the spacing pattern of the elastics (168) disposed on the front belt (106) may be different from the spacing pattern of the elastics (168) disposed on the back belt (108). Thus, the elastics (168) may be disposed such that at least one elastic from the front belt (106) and at least one elastic from the back belt (108) overlap each other at the side seams, while others do not. The elastic (168) may be strategically positioned to provide various benefits to the circular elastic belt (104), including ergonomic fit, fixation to specific parts of the wearer's body, and accommodation for leg movement, for example, the articles disclosed in WO 2016 / 029651, WO 2016 / 029652, WO 2016 / 029653, WO 2016 / 029566, WO 2016 / 029655, WO 2016 / 029656, WO 2017 / 132852, and WO 2017 / 133031, all of which are incorporated herein by reference.

[0038] 3A and 3B, the longitudinal dimension of the front belt (106) may be different from the longitudinal dimension of the rear belt (108), and either one of the distal edges of the front belt (106) and the rear belt (108) may coincide with each other. The rear belt (108) may have a larger longitudinal dimension, and the distal edges of the front belt (106) and the rear belt (108) coincide to create a buttocks cover on the rear side. The front belt (106) may have a larger longitudinal dimension, and the proximal edges of the front belt (106) and the rear belt (108) coincide to create an abdominal cover on the front side. The longitudinal dimension of the folded portion (162FO) of the front belt (106) may be different from the longitudinal dimension of the folded portion (162FO) of the rear belt (108). As will be described in more detail below, and with reference to FIG. 5A , the folds (162FO) can sandwich the chassis (102) and cover the longitudinal edges of the chassis (102) on the front and back sides. The chassis (102) may be positioned offset from the longitudinal center of the article, i.e., shifted to the front or back side. For example, the chassis (102) may be shifted toward the front side to accommodate urine absorption. The front and back folds (162FO) may be adjusted according to the position of the chassis (102) relative to the article.

[0039] Referring to FIG. 1 , first and second side seams (178, 180) joining the side edges of the front belt (106) and the back belt (108) are made from the material of the elastic laminate forming the front belt (106) and the back belt (108). In the present invention, the side seams are made by hot air bonding, which at least partially melts the material of the elastic laminate forming the front belt (106) and the back belt (108), and the side seams (178, 180) have continuity of the melted material along substantially the entire longitudinal dimension. As discussed in more detail below, the side seams (178, 180) herein are formed by hot air bonding. Hot air bonding is advantageous in that the process can be performed at high speed to form a reliable, strong seam. It is desirable that the side seams be strong enough to withstand normal use conditions, i.e., not break when stretched in application or after an article is filled. On the other hand, it is also desirable that the seam be easy to open after use, ie, be manually tearable along the longitudinal dimension for removal from the wearer.

[0040] The side seams of the present invention have a belt minimum peel strength of at least about 6 N / 25 mm, or at least about 8 N / 25 mm, and a belt maximum peel strength of about 18 N / 25 mm or less, as measured herein. Belt minimum / maximum peel strength refers to the average minimum / maximum peel strength among the four seam sections across a specific number of circular elastic belts. Specifically, the strength of a side seam can be represented by four unique sections of two seams per circular elastic belt, namely, the distal (top) and proximal (bottom) edges of the opposing longitudinal edges of the left and right seams. These four unique sections may be identified as "top left," "top right," "bottom left," and "bottom right," and their forces may be identified as the codes FTL, FTR, FBL, and FBR. The average peel strength of each of the four unique sections can be obtained across a specific number of circular elastic belts. Belt minimum peel strength refers to the lowest peel strength among the four unique sections. The maximum belt peel strength refers to the highest peel strength of the four unique parts. By controlling the four unique parts to have a seam strength within a required value across a specific number of circular elastic belts, it is possible to consistently produce circular elastic belts that have seam strength that resists premature tearing during use and is easy to open after use.

[0041] The side seams of the present invention have a top-bottom differential of about 15% or less, or about 13% or less, as measured herein. Referring to the peel strength of the four portions of the seam described above, the top-bottom differential is taken as the absolute value of the difference between the top forces FTL and FTR compared to the bottom forces FBL and FBR. |{(FTL+FTR)-(FBL+FBR)}÷(FBL+FBR)|(%)

[0042] When the top-bottom difference is controlled to a small deviation, the peel experience from the top to the bottom of the seam is perceived as smooth and easy.

[0043] The side seams of the present invention may also have an average peel strength as measured herein, where the combined first and second substrate layers of the elastic belt have a material break point as measured herein, and the average peel strength is about 20% to about 50% of the material break point. The average peel strength refers to the highest frequency force when the force profile is recorded upon opening the side seam. By controlling the difference between the average peel strength and the material break point in this manner, elastic belts can be made from materials that have good tactile feel while also having robust side seam strength.

[0044] Measurements for obtaining seam maximum peel strength, seam minimum peel strength, belt maximum peel strength, belt minimum peel strength, average peel strength and material break point are provided in further detail below.

[0045] Manufacturing method The present invention is also directed to a method of making the above-described circular elastic belt (104), which may be assembled with a chassis (102) to produce a belt-type pant article (100). For example, FIG. 4 shows a schematic diagram of a converting apparatus (300) adapted to produce pant (100). The method of operation of the converting apparatus (300) can be described with reference to the various components of the pant (100) described above and shown in FIGS. 1 and 2. While the following method is provided in the context of the pant (100) shown in FIGS. 1 and 2, various types of pant (100) may be manufactured according to the method disclosed herein, such as, for example, the absorbent articles disclosed in U.S. Patent Application Publication Nos. 2005 / 0107764 (A1), 2012 / 0061016 (A1), and 2012 / 0061015 (A1), which are incorporated herein by reference in their entireties.

[0046] The conversion device (300) shown in FIG. 4 operates to advance the individual chassis (102) along the machine direction so that the lateral axis of each chassis (102) is parallel to the machine direction, and the chassis (102) are spaced apart from one another along the machine direction. Referring to FIGS. 1 and 4, the opposing waist regions (116, 118) of the spaced apart chassis (102) are then connected with continuous front and back belts (406, 408). The chassis (102) is then folded along the lateral axis to bring the continuous front and back belts (406, 408) into a face-to-face relationship, and the continuous front and back belts (406, 408) are joined to one another at joints (336). As will be described in more detail below, the continuous front and back belts (406, 408) are joined to one another at adjacent joints (336a, 336b) that are intermittently spaced apart along the machine direction. Each bond (336a, 336b) may be a separate bond site that extends continuously in the cross machine direction across the width of the continuous front and back belts (406, 408). The continuous front and back belts (406, 408) are then cut in the cross machine direction between adjacent bond (336a, 336b) to create separate pants (100) as shown in FIG.

[0047] As shown in Figure 4, a continuous first substrate layer (462), a continuous second substrate layer (464), and a plurality of elastics (168) are combined to form a continuous elastic laminate (402). More specifically, the continuous first substrate layer (462) has a first surface and an opposite second surface and defines a width in the cross-machine direction, the continuous second substrate layer (464) has a first surface and an opposite second surface and has a width smaller than that of the continuous first substrate layer (462), and the elastics (168) advance in the machine direction and are combined at nip rolls (502) to form the continuous elastic laminate (402), with the elastics (168) bonded between the first surface of the continuous first substrate layer (462) and the first surface of the continuous second substrate layer (464). Prior to entering the nip rolls (502), the elastics (168) are stretched in the machine direction. The elastics may be classified as outer elastics (170) and inner elastics (172). To bond the continuous first substrate layer (462), the continuous second substrate layer (464), and the elastics (170, 172), adhesive (504) may be applied to the elastic (168) and to either or both of the continuous first substrate layer (462) and the continuous second substrate layer (464) to bond the elastics (170, 172) between a first surface of the continuous first substrate layer (462) and a first surface of the opposing continuous second substrate layer (464). Alternatively, the inner and outer elastics (170, 172) may be placed between the continuous first substrate layer (462) and the continuous second substrate layer (464) and sent to an ultrasonic bonding station for bonding together.

[0048] Referring to Figure 5A, the excess width of the continuous first substrate layer (462) may be folded along the machine direction of at least one of the continuous front belt (406) and the continuous back belt (408) such that the continuous first substrate layer (462) is folded, with the folded portion of the continuous first substrate layer defining a continuous fold region (466FO). The folding may be toward the body-facing side such that the first surface of the continuous first substrate layer (462) is joined to itself and / or to the second surface of the continuous second substrate layer (464), as in Figures 3A, 3B, and 5A. Alternatively, the folding may be toward the garment-facing side such that the second surface of the continuous first substrate layer (462) is joined to itself (not shown).

[0049] Referring again to FIG. 4 , from the nip roll (502), the continuous elastic laminate (402) advances in the machine direction to a cutter (506), which cuts the continuous elastic laminate (402) into two continuous belt substrates (referred to as the continuous front belt (406) and the continuous back belt (408)). The cutter (506) may be configured in a variety of ways. For example, in some embodiments, the cutter (506) may be a slitter or die cutter that separates the belt material into two continuous belt substrates with either a straight cut and / or a curved cut. The cutter (506) may also be configured as a perforator that perforates the belt material using lines of weakness, along which the belt material is separated in a subsequent process. From the cutter (506), the continuous front and back belts (406, 408) advance through a diverter (508), which separates the continuous front and back belts (406, 408) from one another in the cross machine direction. From the diverter (508), the continuous front and back belts (406, 408) advance to a nip (316) between a conveyor (308) and a roll (318).

[0050] As shown in Figure 4, a continuous length of chassis assembly (302) is advanced in the machine direction to a conveyor (308) where it is cut into individual chassis (102) using a knife roll (306). After the individual chassis (102) are cut by the knife roll (306), the conveyor (308) rotates to advance the individual chassis (102) in the machine direction, with the longitudinal axes (124) of the chassis (102) generally parallel to the machine direction. As the conveyor (308) rotates, it simultaneously changes the orientation of the advancing chassis (102). The conveyor (308) can also change the speed at which the chassis (102) advance in the machine direction. Various forms of conveying devices can be used with the methods herein, such as those disclosed in U.S. Pat. No. 7,587,966 and U.S. patent application Ser. Nos. 13 / 447,585, 13 / 447,568, 13 / 447,544, and 13 / 447,531.

[0051] As described below with reference to Figures 4, 5A, 5B, 5C and 5D, the chassis (102) is transferred from the conveyor (308) and combined with advancing continuous front and rear belts (406, 408), which are then cut to form the front and rear belts (106, 108) to form the final article (100).

[0052] Referring to Figure 4, the chassis (102) is transferred from the conveyor (308) to a nip (316) between the conveyor (308) and a roll (318) where the chassis (102) is combined with continuous front and back belts (406, 408). The body-facing surface (312) of the continuous front belt (406) may be joined to the garment-facing surface (314) of the chassis (102) along the first waist region (116), and the body-facing surface (312) of the continuous back belt (408) may be joined to the garment-facing surface (314) of the chassis (102) along the second waist region (118). As shown in FIG. 4, adhesive (320) may be applied intermittently to the body-facing surfaces (312) of the continuous front and back belts (406, 408) before being combined with the individual chassis (102) at the nip (316) between the roll (318) and the conveying device (308).

[0053] Referring to FIG. 5A , when the chassis (102) is transferred and combined with the continuous front and back belts (406, 408), the continuous first substrate layer (462), which has a width greater than the continuous second substrate layer (464), may be folded, and the folded portion of the continuous first substrate layer may define a continuous fold region (466FO). The continuous fold region (466FO) may sandwich the continuous second substrate layer (464) with the continuous first substrate layer, as in FIG. 5A . The cross-machine dimension of the continuous fold region (466FO) may substantially match that of the excess dimension of the continuous first substrate layer (462) compared to the continuous second substrate layer (464), ultimately providing a belt structure such as that in FIGS. 3A and 3B . Alternatively, the cross-machine dimension of the continuous fold-over portion (466FO) region may be smaller than the excess dimension of the continuous first substrate layer (462) compared to the continuous second substrate layer (464), as in Figure 5A. While adhering the continuous fold-over portion (466FO) region to the continuous second substrate layer (464), the front and rear longitudinal edge regions of the individual chassis (102) may be intermittently sandwiched between the continuous fold-over portion (466FO) region and the continuous second substrate layer (464). This secures the attachment of the chassis (102) to the continuous front and back belts (406, 408) and further covers the front and rear longitudinal edges of the chassis (102).

[0054] 4 and 5B, the continuous length absorbent article (400) is defined by a plurality of individual chassis (102) spaced apart from one another along the machine direction and connected to one another by continuous back belts (408) and continuous front belts (406). Referring to FIGS. 4, 5A, and 5B, the continuous length article (400) advances from the nip (316) to a folding apparatus (332). In the folding apparatus (332), each chassis (102) is folded in the cross-machine direction along its lateral axis (126) to position the front waist region (116), and in particular its inner body-facing surface (312), in a mutually facing orientation with the inner body-facing surface (312) of the back waist region (118). The folding of the chassis (102) also positions the body-facing surface (312) of the continuous rear back belt (408) extending between each chassis (102) in opposing relationship with the body-facing surface (312) of the continuous front belt (406) extending between each chassis (102). This therefore overlaps the continuous front belt (406) and the continuous back belt (408). Either edge of the front belt (106) and the back belt (108) may coincide. When the chassis (102) is folded at the midpoint of the assembly traverse of the machine, the distal edges of the continuous front and back belts coincide.

[0055] As shown in Figures 4, 5B, and 5C, the folded individual chassis (102) connected with the continuous front and rear belts (406, 408) are advanced from the folding device (332) to the joining module (334). The joining module (334) operates to join the overlapping areas (362), thereby creating individual joints (336a, 336b). The overlapping areas (362) include the portion of the continuous rear belt (408) that extends between each chassis 102 and the portion of the continuous front belt (406) that extends between each chassis 102. 4 and 5D, the continuous length of article advances from the joining module (334) to a knife roll (338) where the continuous front belt (406) and the continuous back belt (408) are cut along the cross machine direction between adjacent bonds (336a, 336b) to form individual finished pant articles (100). Thus, one bond (336a) can correspond to and form a first side seam (178) on the article (100), and the other bond (336b) can correspond to and form a second side seam (180) on the subsequently advancing article.

[0056] 4, the converting apparatus may include a joining module (334) for creating the joints (336a, 336b). The joining module (334) is configured to intermittently splice the resulting assembly by directing a jet of heated air to at least partially melt the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408) and compress the melted portions between the outer circumferential surface (370) of the anvil roll (368) and a pressing member (380).

[0057] As noted above, referring to Figures 3A, 3B, and 5C, the regions of the assembly to be bonded may include regions made of six substrate layers and four substrate layers. The six-layer region includes continuous fold-over (466FO) regions coming from both the continuous front and back belts (406, 408). Given this difference in the number of substrate layers in the assemblies, seam strength may vary when the six-layer and four-layer regions are seamed in a single seaming step, utilizing a uniform compression surface along the longitudinal dimension of the seam. When the seam strength of the resulting article varies along the longitudinal dimension of the side seam, this may result in a larger top-bottom difference, a belt maximum peel strength that is too high, or a belt minimum peel strength that is too low. The process for forming hot air bonds of the present invention may include various methods for preventing such differences in seam strength while maintaining seam strength within a range that allows the side seam to withstand normal use conditions and be easy to open after use. Specifically, the process may provide a relatively lower bonding pressure to the six-layer region compared to the four-layer region. Alternatively or additionally, the process may provide more than one bonding pressure to the four-layer region, thus compensating for the otherwise lower bonding pressure applied to the four-layer region.

[0058] The assembly obtained at the stage of Figure 5C may be seamed by directing a jet of heated air to at least partially melt the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408), and then compressing the melted portions between the outer circumferential surface (370) of the anvil roll (368) and the pressing member (380), the compression being performed at least twice. The compression may include a first compression and a second compression, where the compression regions of the first compression and the second compression vary across the longitudinal dimension of the side seam.

[0059] For example, Figure 6A1 shows a schematic side view of a first embodiment of a joining module (334) that may be utilized with the methods and apparatus herein. As shown in Figure 6A1, the joining module (334) may include a splicing drum (364R) and a compression stage (335) located adjacent to the splicing drum (364R). With reference to Figure 6B1, the splicing drum (364R) may include an outer circumferential surface (376) and may be adapted to rotate about an axis of rotation (374). The splicing drum (364R) may also include a plurality of splicing stations (348) positioned radially inward from the outer circumferential surface (376) and the drum aperture (366), as in Figure 6B3. Each splicing station (348) may include a hot air nozzle (378) directing a jet of heated air through a drum aperture (366) to at least partially melt the overlap area (362) of the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408). While the splicing drum (364R) shown in FIG. 6B1 includes six splicing stations (348), the splicing drum (364) may be configured to include more or less than six splicing stations (348). The assembly may be rotated around the splicing drum (364R) to provide sufficient time for melting, such that the melted portions can be compressed to provide the side seam of the resulting article with continuity of melted material along substantially its entire longitudinal dimension. 6A1 and 6B1, the hot air nozzles (378) can actively direct heated air only into the active region (390) of the splicing drum (364R). Referring to FIG. 6A1, the compression stage (335) can be located immediately after exiting the splicing drum (364R). The compression stage (335) can include a pair of anvil rolls (368) and a pressing member (380) that engage with each other. The anvil roll (368) includes an outer circumferential surface (370) and is adapted to rotate about an axis of rotation (372).The press member 380 may include a pair of protrusions 422 for engaging the outer circumferential surface 370 to form a pair of adjacent side seams. By providing a compression stage 335 independent of the seaming drum 364R, the anvil roll 368 and the press member 380 can each be adjusted according to the type of assembly to be seamed. This is advantageous in that assemblies made from various types of substrates and various sizes can be seamed without the need to manufacture the seaming drum 364R. The outer circumferential surface 370 of the anvil roll 368 and the protrusions 422 of the press member 380 for engaging the outer circumferential surface 370 may have configurations to provide various bonding pressures, as described in more detail below.

[0060] In another example, Figures 6A2 and 6A3 show schematic side views of a second and third embodiment of the joining module (334), respectively. Like the first embodiment, the second and third embodiments shown in Figures 6A2 and 6A3 have differently configured compression stages (335), but may include a splicing drum (364R) as in Figure 6B1. Referring to Figure 6A2, the compression stage (335) may be located immediately after exiting the splicing drum (364R), and the compression stage (335) may include two sets of engaged anvil rolls (368) and press members (380). Referring to Figure 6A3, the compression stage (335) may be located immediately after exiting the splicing drum (364R), and the compression stage (335) may include one anvil roll (368) engaged with two press members (380). By providing a compression stage (335) that is separate from the seaming drum (364R) and further includes two or more compression sections, the multiple compression sections of FIGS. 6A2 and 6A3 can be configured to press against different portions of the assembly, which may have different calipers or layers of nonwoven fabric, and / or to press against some portions multiple times. This is also advantageous in that assemblies made from various types of substrates and various sizes can be spliced together by modifying one or more of the anvil roll (368) and the press member (380) without having to manufacture the seaming drum (364R). The outer peripheral surface (370) of the anvil roll (368) and the protrusions (422) of the press member (380) for engaging the outer peripheral surface (370) may be configured to provide various bonding pressures, as described in more detail below.

[0061] Figure 6A4 shows a schematic side view of a fourth embodiment of a joining module (334) that can be utilized with different methods and apparatus than those described above. As shown in Figure 6A4, the joining module (334) can include a splicing drum (364C) and an anvil roll (368) configured to engage a pressing member (380) contained within the splicing drum (364C), with the engagement configured to occur immediately prior to exiting the splicing drum (364C) and the additional compression stage (335). With reference to Figures 6B2 and 6B3, the splicing drum (364C) can include an outer circumferential surface (376) and is adapted to rotate about an axis of rotation (374), with the splicing drum (364C) including a cam feature that allows the splicing station (348) to move radially inward and outward. For example, referring to FIGS. 6A4 and 6B2, the splicing station (348), when positioned radially inward from the outer circumferential surface (376), can receive the continuous front and rear belts (406, 408) and, after allowing sufficient time for them to fuse within the active area (390), move radially outward so that the press member (380) can engage the anvil roll (368) just before exiting the splicing drum (364C). Once spliced, the continuous front and rear belts (406, 408) can be sent to the compression stage (335). The compression stage (335) can include a pair of anvil rolls (368) and press member (380) that engage with each other. FIG. 6A5 shows a schematic side view of a fifth embodiment of the joining module (334). Similar to the fourth embodiment, the fifth embodiment shown in Figure 6A5 has a different configuration of the compression stage (335), but may include a splicing drum (364C) as in Figure 6B2. There may be a compression stage (335) that includes two sets of interlocking anvil rolls (368) and pressing members (380).By providing one press site within the splicing drum (364C) and another press site(s) in the compression stage (335), the multiple press sites of FIGS. 6A4 and 6A5 can be configured to press against different portions of a substrate, which may have different calipers or layers of nonwoven fabric, and / or to press against some portions multiple times. This is also advantageous in that assemblies made from different types of substrates and different sizes can be spliced together in the splicing drum (364C) by default once, with one or more of the anvil roll (368) and press member (380) further modified to meet additional assembly needs. The outer circumferential surface (370) of the anvil roll (368) and the protrusions (422) of the press member (380) for engaging the outer circumferential surface (370) can have configurations to provide various bonding pressures, as described in more detail below.

[0062] Referring to Figures 6A1-6A5, the outer peripheral surface (370) of the anvil roll (368) that engages the splicing drum (364C), as well as those in the compression stage (335), can have various configurations to effectively splice regions with more and less material. Referring to Figure 6C, the outer peripheral surface of the anvil roll may include a grooved region (370G) with alternating intermittent concave surfaces in the cross-machine direction. The outer peripheral surface may be entirely made of grooved regions (370G) (not shown). Alternatively, the outer peripheral surface may be made of grooved regions (370G) and flat regions (370F) without the intermittent concave surfaces, as in Figure 6C. The recesses in the grooved regions (370G) provide voids for the applied pressure when compressed against the pressing member (380), thereby adjusting the splice strength. Seams created by the grooved regions (370G) may have reduced strength compared to seams created by the flat regions (370F). In the annular elastic belt (104) of the present invention, regions with more material are pressed together with greater pressure due to the thickness of the compressed regions, thus resulting in unnecessarily high seam strength. On the other hand, regions with less material may result in lower seam strength. In other words, if the seam is compressed with the same pressure along its longitudinal dimension, this may result in a gradation in seam strength along the seam. Therefore, the fold region (162F-O) may be configured to meet the grooved region (370G) of the outer circumferential surface (370) of the anvil roll (368) to provide a lower compression pressure.

[0063] Referring to FIG. 6D, the compression stage (335) also includes a pressing member (380) that compresses the partially melted overlap area against the outer peripheral surface (370) of the anvil roll (368). The pressing member (380) may be substantially rectangular in shape and includes two protrusions (422) for engaging with the machine direction centers of the melted portions to form first and second bonded portions (336a, 336b) (not shown). The protrusions may be flat. Referring to FIG. 6D, each of the protrusions (422) may include a normal surface (423) and a concave surface (421), where the normal surface (423) is positioned to engage the outer peripheral surface of the anvil roll at a smaller distance (H) and thus provide a higher compression pressure, while the intended surface (421) provides a relatively lower compression pressure. The fold region (162FO) may be configured to meet the concave surface (421) of the protrusions (422). The height difference (H) between the concave surface (421) and the normal surface (423) may be about 0.1 mm to about 0.6 mm, or about 0.2 mm to about 0.4 mm. The surface may be slightly tapered in the machine direction to avoid easy wear.

[0064] As previously described above with reference to Figures 4, 5C, and 5D, once the bonds (336a, 336b) are formed, the article (400) advances in the machine direction to the knife roll (338), where the continuous front and back belts (406, 408) are cut along the cross-machine direction between the bonds (336a, 336b) to create a first side seam (178) on the article (100) and a second side seam (180) on the subsequently advancing article. The press member (380) and anvil roll surface (370) may be coated, for example, with a plasma coating, polytetrafluoroethylene, or silicone.

[0065] measurement 1. Preparation of Final Product Test Specimens Test specimens for the following measurements are taken from the final wearable article sample or the circular elastic belt (104) sample, unless otherwise specified. To obtain a belt specimen from the final wearable article sample, the belt is manually removed from the chassis (102).

[0066] For each set of measurements, test specimens are obtained from six final wearable articles from the same area of each article. At least two hours prior to testing, test specimens are preconditioned in a room maintained at 23±2°C and 50±5% relative humidity. All testing is performed in a room maintained at 23±2°C and 50±5% relative humidity.

[0067] 2. Minimum belt peel strength, maximum belt peel strength, top / bottom difference The equipment used is an MTS Criterion C42 running TestWorks 4 Software with standard tensiometer jaws or equivalent.

[0068] Four unique seam specimens are obtained from one belt specimen by cutting the top (distal) and bottom (proximal) edges of the opposing longitudinal edges of the left and right seams with scissors to a longitudinal dimension (cross-machine direction) of 25 mm and a transverse dimension (machine direction) of 50 mm. When the seam edges are discontinuous, care is taken to avoid such discontinuities and to sample a continuous portion of the seam. Each of the four unique seam specimens from one belt specimen is provided identifiable as "top left," "top right," "bottom left," and "bottom right."

[0069] (1) Set the seam test specimen so that the transverse direction of the belt is aligned with the vertical direction of the equipment. Without applying tension, clamp the seam test specimen between the upper and lower jaws of the tension gauge as linearly as possible.

[0070] (2) Take the extension measurement from the point where the force curve leaves the zero line.

[0071] (3) A constant rate of extension of 460 mm / min is applied.

[0072] (4) Pull the seam specimen until the seam is completely separated. Record the peak force (N / 25 mm).

[0073] (5) For each of the "upper left," "upper right," "lower left," and "lower right" test pieces, obtain and average the average peak force of the six values of the six seam test pieces, and name each average value as FTL, FTR, FBL, and FBR. The minimum value of FTL, FTR, FBL, and FBR is the minimum belt peel strength, and the maximum value of FTL, FTR, FBL, and FBR is the maximum belt peel strength.

[0074] (6) Obtain the top-bottom difference as follows: |{(FTL+FTR)-(FBL+FBR)}÷(FBL+FBR)|(%)

[0075] 3.Average peel strength The equipment used is an MTS Criterion C42 running TestWorks 4 Software with standard tensiometer jaws or equivalent.

[0076] Left and right seam specimens were obtained from one belt specimen by cutting the left and right seams with scissors across the entire longitudinal length of the seam and in the 50 mm transverse dimension (machine direction). The left and right seams were separately subjected to the following measurements.

[0077] (1) Set up the test specimen so that the transverse direction of the belt is aligned with the vertical direction of the instrument. Clamp the distal edge of the specimen between the upper and lower tensiometer jaws as linearly as possible without applying tension.

[0078] (2) A constant stretching rate of 2000 mm / min is applied.

[0079] (3) Pull the specimen until the seam is completely separated. Record the force distribution to an accuracy of 0.01 N.

[0080] (4) Record the force (N) at the highest frequency as in Figure 7. Average the highest frequencies from the left seam specimen and the right seam specimen to obtain the average peel strength (N).

[0081] 4.Material break point The equipment used is an MTS Criterion C42 running TestWorks 4 Software with standard tensiometer jaws or equivalent. The measurement uses raw material for the first substrate layer (162) and raw material for the second substrate layer (164). Depending on how the substrate is planned to be assembled, the substrate is cut into a lateral dimension (machine direction) of 25 mm and a longitudinal dimension (cross-machine direction) of 50 mm to provide the test specimens. 30 test specimens are obtained using different lots of substrate layers or different areas of the substrate layer.

[0082] (1) Set the test specimen so that the longitudinal direction of the layer as it is planned to be introduced into the belt coincides with the vertical direction of the instrument. Clamp the layer to leave an initial gauge length of 25 mm. Clamp the test specimen between the upper and lower tensiometer jaws as linearly as possible without applying tension.

[0083] (2) A constant stretching rate of 2000 mm / min is applied.

[0084] (3) The specimen is pulled until it breaks completely. The force distribution is recorded to an accuracy of 0.01 N.

[0085] (4) As in Figure 7, the force (N) at the highest frequency is the material break point (N). [Example]

[0086] Examples 1-5, identified in Table 1 below, were subjected to various measurements and in-use tests. Examples 1-3 were commercially available products not manufactured according to the manufacturing method of the present invention. Examples 4-5 were manufactured according to the manufacturing method of the present invention. All examples were made with very similar raw materials and elasticity profiles that were within the manufacturer's specifications.

[0087] The examples were subjected to the measurements detailed above, and the belt minimum peel strength, belt maximum peel strength, and top-bottom difference were obtained and recorded below in Table 1. Additionally, the examples were subjected to the in-use tests detailed below.

[0088] Tests in use Thirty panelists (10 panelists each from the United States, Japan, and the United Kingdom) who were caregivers of infants, a mix of boys and girls, aged 6-48 months and weighing 9-14 kg, and who were also pant product users, were provided with sufficient test product. Each panelist used the test product and tore the side seam according to their usual habits. Most of the time, the infant wearer stood with the side seam torn open.

[0089] The panelists were asked to observe whether there was any horizontal tearing during the opening. Horizontal tearing refers to the phenomenon where the tear line is deflected away from the side seam, rather ripping the elastic belt. Horizontal tearing includes tears in various directions that are not necessarily horizontal, as long as the tear in the side seam is deflected or derailed. The occurrence of horizontal tearing is recorded by the panelists.

[0090] [Table 1]

[0091] Examples 1 to 3 within the product specifications at the time of manufacturing provided side seams with varying peel strengths depending on the manufacturing site and / or lot, meaning that stable side seam quality could not be obtained. This unstable quality resulted in significant differences in the occurrence of horizontal tearing, leading to low consumer acceptance.

[0092] Examples 4-5, manufactured according to the method of the present invention, provided more consistent side seam quality. Examples 4-5 according to the present invention had the same product specifications as Examples 1-3, except for belt minimum peel strength, belt maximum peel strength, and top-bottom differential. Furthermore, in-use testing of Examples 4-5 showed significantly fewer horizontal tears. The parameters of the present invention provide good predictability of consumer acceptance.

[0093] The dimensions and values disclosed herein should not be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm." Furthermore, every numerical range given throughout this specification includes every narrower numerical range that falls within such broader numerical range.

[0094] All documents cited herein, including cross-referenced documents or related patents or applications, are incorporated herein by reference in their entirety unless expressly excluded or otherwise limited. The citation of any document shall not be deemed to be prior art to any invention disclosed or claimed herein, or that it alone, or in combination with any other reference(s), teaches, suggests, or discloses any such invention. Furthermore, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0095] While particular embodiments of the present invention have been illustrated and described, it would be obvious 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. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A circular elastic belt (104) having a longitudinal direction and a lateral direction, A front belt (106) and a rear belt (108), each of which is an elastic laminate including a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162) and the second substrate layer (164), and each of which is an elastic laminate including a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the first substrate layer (162), the second substrate layer (164), and a plurality of elastic bodies (168) bonded between the second substrate layer (164), and each of which is an elastic laminate including a first substrate layer (162), a second substrate layer (164), and a plurality of elastic bodies (168) bonded between ... second substrate layer (164), and a plurality of elastic bodies (168) bonded between the a front belt (106) and a rear belt (108) further comprising a folded portion (162FO) of at least one of the first base layer (162) and the second base layer (164), wherein the folded portion (162FO) of the front belt (106) has a shorter longitudinal dimension than the front belt (106), and the folded portion (162FO) of the rear belt (108) has a shorter longitudinal dimension than the front belt (106); a pair of side seams joining the side edges of the front belt (106) and the back belt (108) such that the folded portion (162FO) of the front belt and the folded portion (162FO) of the back belt cooperatively define a distal edge of the annular elastic belt (104), the side seams being made by hot air bonding that at least partially melts a material of the elastic laminate, the side seams having continuity of the melted material along substantially the entire longitudinal dimension thereof; Circular elastic belt (104), wherein said side seams have a belt minimum peel strength of at least about 6 N / 25 mm, a belt maximum peel strength of no more than 18 N / 25 mm, and a top-to-bottom differential of no more than 15%, as measured herein.

2. 2. The circular elastic belt of claim 1, wherein the side seams have an average peel strength as measured herein, the first and second substrate layers (164) combined have a material break point as measured herein, and the average peel strength is from about 20% to about 50% of the material break point.

3. 3. The circular elastic belt of claim 1, wherein the first substrate layer (162) and the second substrate layer (164) each have a material break point according to the measurements herein, the material break point being less than about 8N.

4. 4. The circular elastic belt according to claim 1, wherein the elastics (168) are arranged such that at least one elastic from the front belt (106) and at least one elastic from the back belt (108) overlap each other at the side seams.

5. 5. The circular elastic belt of claim 1, wherein the elastic members (168) are intermittently arranged at various intervals, and the spacing pattern of the elastic members (168) arranged on the front belt (106) is different from the spacing pattern of the elastic members (168) arranged on the rear belt (108).

6. 6. The circular elastic belt according to claim 1, wherein the front belt and the back belt have a maximum basis weight of at least about 90 gsm in the area including the folded portion.

7. 7. The circular elastic belt of claim 1, wherein the longitudinal dimension of the front belt (106) is different from the longitudinal dimension of the rear belt (108), and the distal edges of the front belt (106) and the rear belt (108) coincide with each other.

8. 8. The circular elastic belt according to claim 1, wherein the first substrate layer (162) and the second substrate layer (164) are nonwoven materials that differ in at least one of basis weight, stiffness, and texture.

9. 9. The circular elastic belt of claim 8, wherein at least one of the first substrate layer (162) and the second substrate layer (164) has a plurality of openings or bonds.

10. 9. The circular elastic belt of claim 8, wherein said first substrate layer (162) is a nonwoven fabric made from carded air-through fibers.

11. A wearable article comprising a central chassis (102) and the annular elastic belt (104) of any one of claims 1 to 10, wherein the central chassis (102) is bridged from the center of the front belt (106) to the center of the back belt (108).

12. A method for manufacturing an annular elastic belt (104), comprising the steps of: advancing a continuous first substrate layer (462) in a machine direction, said continuous first substrate layer (462) having a first surface and an opposite second surface and defining a width in a cross-machine direction; advancing a continuous second substrate layer (464) in the machine direction, the continuous second substrate layer (464) having a first surface and an opposite second surface and having a width smaller than the continuous first substrate layer (462); advancing a plurality of elastics (168) in an elongated state in the machine direction; bonding the elastic body (168) between the first surface of the continuous first substrate layer (462) and the first surface of the continuous second substrate layer (464); cutting the assembly in the machine direction, wherein the continuous first substrate layer (462) and the continuous second substrate layer (464) are overlapped to define a continuous front belt (406) and a continuous back belt (408); folding the continuous first substrate layer (462) along the machine direction of at least one of the continuous front belt (406) and the continuous back belt, wherein the folded portion of the continuous first substrate layer (462) defines a continuous fold (466FO) area; overlapping the continuous front belt (406) and the continuous back belt (408) so that cross-machine edges of the continuous front belt (406) and the continuous back belt (408) coincide; splicing the obtained assembly intermittently in the machine direction and continuously in the cross-machine direction by directing a jet of heated air to at least partially melt the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408) and compressing the melted portions between the outer circumferential surface (370) of an anvil roll (368) and a pressing member (380); The folded portion of the front belt has a shorter longitudinal dimension than the front belt, and the folded portion of the rear belt has a shorter longitudinal dimension than the front belt, the outer peripheral surface of the anvil roll includes grooved regions (370G) having alternating intermittent concave surfaces in the cross-machine direction and flat regions (370F) lacking the intermittent concave surfaces, and the continuous fold (466FO) regions are configured to meet the grooved regions (370G) of the anvil roll upon compression, thereby forming the side seams having a belt minimum peel strength of at least about 6 N / 25 mm, a belt maximum peel strength of 18 N / 25 mm or less, and a top-to-bottom difference of 15% or less, as measured herein.

13. 13. The method of claim 12, wherein the pressing member (380) includes a normal surface (423) and a concave surface (421), and the continuous fold (466FO) region is configured to meet the concave surface of the pressing member (380).

14. A method for manufacturing an annular elastic belt (104), comprising the steps of: advancing a continuous first substrate layer (462) in a machine direction, said continuous first substrate layer (462) having a first surface and an opposite second surface and defining a width in a cross-machine direction; advancing a continuous second substrate layer (464) in the machine direction, the continuous second substrate layer (464) having a first surface and an opposite second surface and having a width smaller than the continuous first substrate layer (462); advancing a plurality of elastics (168) in an elongated state in the machine direction; bonding the elastic body (168) between the first surface of the continuous first substrate layer (462) and the first surface of the continuous second substrate layer (464); cutting the assembly in the machine direction, wherein the continuous first substrate layer (462) and the continuous second substrate layer (464) are overlapped to define a continuous front belt (406) and a continuous back belt (408); folding the continuous first substrate layer (462) along the machine direction of at least one of the continuous front belt (406) and the continuous back belt, wherein the folded portion of the continuous first substrate layer (462) defines a continuous fold (466FO) area; overlapping the continuous front belt (406) and the continuous back belt (408) so that cross-machine edges of the continuous front belt (406) and the continuous back belt (408) coincide; splicing the obtained assembly intermittently in the machine direction and continuously in the cross-machine direction by directing a jet of heated air to at least partially melt the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408) and compressing the melted portions between the outer circumferential surface (370) of an anvil roll (368) and a pressing member (380); The folded portion of the front belt has a shorter longitudinal dimension than the front belt, and the folded portion of the rear belt has a shorter longitudinal dimension than the front belt, 10. The method of claim 1, wherein the pressing member (380) comprises a normal surface (423) and a concave surface (421), and the continuous fold (466FO) region is configured to meet the concave surface of the pressing member (380), thereby forming the side seam with a belt minimum peel strength of at least about 6 N / 25 mm, a belt maximum peel strength of no more than 18 N / 25 mm, and a top-to-bottom differential of no more than 15%, as measured herein.

15. A method for manufacturing an annular elastic belt (104), comprising the steps of: advancing a continuous first substrate layer (462) in a machine direction, said continuous first substrate layer (462) having a first surface and an opposite second surface and defining a width in a cross-machine direction; advancing a continuous second substrate layer (464) in the machine direction, the continuous second substrate layer (464) having a first surface and an opposite second surface and having a width smaller than the continuous first substrate layer (462); advancing a plurality of elastics (168) in an elongated state in the machine direction; bonding the elastic body (168) between the first surface of the continuous first substrate layer (462) and the first surface of the continuous second substrate layer (464); cutting the assembly in the machine direction, wherein the continuous first substrate layer (462) and the continuous second substrate layer (464) are overlapped to define a continuous front belt (406) and a continuous back belt (408); folding the continuous first substrate layer (462) along the machine direction of at least one of the continuous front belt (406) and the continuous back belt, wherein the folded portion of the continuous first substrate layer (462) defines a continuous fold (466FO) area; overlapping the continuous front belt (406) and the continuous back belt (408) so that cross-machine edges of the continuous front belt (406) and the continuous back belt (408) coincide; and seaming the obtained assembly intermittently in the machine direction and continuously in the cross-machine direction to form side seams by directing a jet of heated air to at least partially melt the substrate of the continuous front belt (406) and the substrate of the continuous back belt (408) and compressing the melted portions between an outer circumferential surface (370) of an anvil roll (368) and a pressing member (380), The folded portion of the front belt has a shorter longitudinal dimension than the front belt, and the folded portion of the rear belt has a shorter longitudinal dimension than the front belt, The compression is performed at least twice; a first compression and a second compression, the compression regions of the first compression and the second compression varying across the longitudinal dimension of the side seam, whereby the side seam is formed to have a belt minimum peel strength of at least about 6 N / 25 mm, a belt maximum peel strength of no more than 18 N / 25 mm, and a top-to-bottom differential of no more than 15%, as measured herein.

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